This is manual.info, produced by makeinfo version 4.8 from manual.texi.

START-INFO-DIR-ENTRY
* mysql: (mysql).               MySQL documentation.
END-INFO-DIR-ENTRY


File: manual.info,  Node: Top,  Next: introduction,  Prev: (dir),  Up: (dir)

This is the Reference Manual for the MySQL Database System, version
5.1, through release 5.1.28. It is not intended for use with older
versions of the MySQL software due to the many functional and other
differences between MySQL 5.1 and previous versions. If you are using
an earlier release of the MySQL software, please refer to the `MySQL
5.0 Reference Manual' (http://dev.mysql.com/doc/refman/5.0/en/), which
covers the 5.0 series of MySQL software releases, or to `MySQL 3.23,
4.0, 4.1 Reference Manual' (http://dev.mysql.com/doc/refman/4.1/en/),
which covers the 3.23, 4.0, and 4.1 series of MySQL software releases.
Differences between minor versions of MySQL 5.1 are noted in the present
text with reference to release numbers (5.1.X).

* Menu:

* introduction::                 General Information
* installing::                   Installing and Upgrading MySQL
* tutorial::                     Tutorial
* programs::                     MySQL Programs
* server-administration::        MySQL Server Administration
* backup-and-recovery::          Backup and Recovery
* optimization::                 Optimization
* language-structure::           Language Structure
* internationalization-localization::  Internationalization and Localization
* data-types::                   Data Types
* functions::                    Functions and Operators
* sql-syntax::                   SQL Statement Syntax
* storage-engines::              Storage Engines
* ha-overview::                  High Availability and Scalability
* ha-vm::                        MySQL and Virtualization
* ha-memcached::                 Using MySQL with `memcached'
* mysql-proxy::                  MySQL Proxy
* load-balancer::                MySQL Load Balancer
* replication::                  Replication
* mysql-cluster::                MySQL Cluster
* partitioning::                 Partitioning
* spatial-extensions::           Spatial Extensions
* stored-procedures::            Stored Procedures and Functions
* triggers::                     Triggers
* events::                       Event Scheduler
* views::                        Views
* information-schema::           `INFORMATION_SCHEMA' Tables
* precision-math::               Precision Math
* apis::                         APIs and Libraries
* connectors::                   Connectors
* extending-mysql::              Extending MySQL
* faqs::                         MySQL 5.1 Frequently Asked Questions
* error-handling::               Errors, Error Codes, and Common Problems
* news::                         MySQL Change History
* restrictions::                 Restrictions and Limits
* credits::                      Credits


File: manual.info,  Node: introduction,  Next: installing,  Prev: Top,  Up: Top

1 General Information
*********************

* Menu:

* manual-info::                  About This Manual
* manual-conventions::           Conventions Used in This Manual
* what-is-mysql-ab::             Overview of MySQL AB
* what-is::                      Overview of the MySQL Database Management System
* roadmap::                      MySQL Development Roadmap
* information-sources::          MySQL Information Sources
* bug-reports::                  How to Report Bugs or Problems
* compatibility::                MySQL Standards Compliance

The MySQL(R) software delivers a very fast, multi-threaded, multi-user,
and robust SQL (Structured Query Language) database server. MySQL
Server is intended for mission-critical, heavy-load production systems
as well as for embedding into mass-deployed software. MySQL is a
registered trademark of MySQL AB.

The MySQL software is Dual Licensed. Users can choose to use the MySQL
software as an Open Source product under the terms of the GNU General
Public License (`http://www.fsf.org/licenses/') or can purchase a
standard commercial license from MySQL AB. See
`http://www.mysql.com/company/legal/licensing/' for more information on
our licensing policies.

The following list describes some sections of particular interest in
this manual:

   * For a discussion about the capabilities of the MySQL Database
     Server, see *Note features::.

   * For future plans, see *Note roadmap::.

   * For installation instructions, see *Note installing::.  For
     information about upgrading MySQL, see *Note upgrade::.

   * For a tutorial introduction to the MySQL Database Server, see
     *Note tutorial::.

   * For information about configuring and administering MySQL Server,
     see *Note server-administration::.

   * For information about setting up replication servers, see *Note
     replication::.

   * For answers to a number of questions that are often asked
     concerning the MySQL Database Server and its capabilities, see
     *Note faqs::.

   * For a list of currently known bugs and misfeatures, see *Note
     bugs::.

   * For a list of all the contributors to this project, see *Note
     credits::.

   * For a history of new features and bugfixes, see *Note news::.

   * For tips on porting the MySQL Database Software to new
     architectures or operating systems, see MySQL Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

   * For benchmarking information, see the `sql-bench' benchmarking
     directory in your MySQL distribution.

*Important*:

To report errors (often called `bugs'), please use the instructions at
*Note bug-reports::.

If you have found a sensitive security bug in MySQL Server, please let
us know immediately by sending an email message to <security@mysql.com>.


File: manual.info,  Node: manual-info,  Next: manual-conventions,  Prev: introduction,  Up: introduction

1.1 About This Manual
=====================

This is the Reference Manual for the MySQL Database System, version
5.1, through release 5.1.28. It is not intended for use with older
versions of the MySQL software due to the many functional and other
differences between MySQL 5.1 and previous versions. If you are using an
earlier release of the MySQL software, please refer to the `MySQL 5.0
Reference Manual' (http://dev.mysql.com/doc/refman/5.0/en/), which
covers the 5.0 series of MySQL software releases, or to `MySQL 3.23,
4.0, 4.1 Reference Manual' (http://dev.mysql.com/doc/refman/4.1/en/),
which covers the 3.23, 4.0, and 4.1 series of MySQL software releases.
Differences between minor versions of MySQL 5.1 are noted in the
present text with reference to release numbers (5.1.X).

Because this manual serves as a reference, it does not provide general
instruction on SQL or relational database concepts. It also does not
teach you how to use your operating system or command-line interpreter.

The MySQL Database Software is under constant development, and the
Reference Manual is updated frequently as well. The most recent version
of the manual is available online in searchable form at
`http://dev.mysql.com/doc/'. Other formats also are available there,
including HTML, PDF, and Windows CHM versions.

The Reference Manual source files are written in DocBook XML format.
The HTML version and other formats are produced automatically,
primarily using the DocBook XSL stylesheets. For information about
DocBook, see `http://docbook.org/'

The DocBook XML sources of this manual are available from
`http://dev.mysql.com/tech-resources/sources.html'.  You can check out
a copy of the documentation repository with this command:

     svn checkout http://svn.mysql.com/svnpublic/mysqldoc/

If you have questions about using MySQL, you can ask them using our
mailing lists or forums. See *Note mailing-lists::, and *Note forums::.
If you have suggestions concerning additions or corrections to the
manual itself, please send them to the documentation team at
<docs@mysql.com>.

This manual was originally written by David Axmark and Michael `Monty'
Widenius. It is maintained by the MySQL Documentation Team, consisting
of Paul DuBois, Stefan Hinz, Jon Stephens, Martin MC Brown, and Tony
Bedford. For the many other contributors, see *Note credits::.

The copyright to this manual is owned by the Swedish company MySQL AB.
MySQL(R) and the MySQL logo are registered trademarks of MySQL AB.
Other trademarks and registered trademarks referred to in this manual
are the property of their respective owners, and are used for
identification purposes only.


File: manual.info,  Node: manual-conventions,  Next: what-is-mysql-ab,  Prev: manual-info,  Up: introduction

1.2 Conventions Used in This Manual
===================================

This manual uses certain typographical conventions:

   * `Text in this style' is used for SQL statements; database, table,
     and column names; program listings and source code; and
     environment variables. Example: `To reload the grant tables, use
     the `FLUSH PRIVILEGES' statement.'

   * Text in this style indicates input that you type in examples.

   * `Text in this style' indicates the names of executable programs
     and scripts, examples being `mysql' (the MySQL command line client
     program) and `mysqld' (the MySQL server executable).

   * TEXT IN THIS STYLE is used for variable input for which you should
     substitute a value of your own choosing.

   * Filenames and directory names are written like this: `The global
     `my.cnf' file is located in the `/etc' directory.'

   * Character sequences are written like this: `To specify a wildcard,
     use the ``%'' character.'

   * _Text in this style_ is used for emphasis.

   * *Text in this style* is used in table headings and to convey
     especially strong emphasis.

When commands are shown that are meant to be executed from within a
particular program, the prompt shown preceding the command indicates
which command to use. For example, `shell>' indicates a command that
you execute from your login shell, and `mysql>' indicates a statement
that you execute from the `mysql' client program:

     shell> type a shell command here
     root-shell> type a shell command as ROOT here
     mysql> type a mysql statement here

In some areas different systems may be distinguished from each other to
show that commands should be executed in two different environments.
For example, while working with replication the commands might be
prefixed with `master' and `slave':

     master> type a mysql command on the replication master here
     slave> type a mysql command on the replication slave here

The `shell' is your command interpreter. On Unix, this is typically a
program such as `sh', `csh', or `bash'. On Windows, the equivalent
program is `command.com' or `cmd.exe', typically run in a console
window.

When you enter a command or statement shown in an example, do not type
the prompt shown in the example.

Database, table, and column names must often be substituted into
statements. To indicate that such substitution is necessary, this
manual uses DB_NAME, TBL_NAME, and COL_NAME. For example, you might see
a statement like this:

     mysql> SELECT COL_NAME FROM DB_NAME.TBL_NAME;

This means that if you were to enter a similar statement, you would
supply your own database, table, and column names, perhaps like this:

     mysql> SELECT author_name FROM biblio_db.author_list;

SQL keywords are not case sensitive and may be written in any
lettercase. This manual uses uppercase.

In syntax descriptions, square brackets (``['' and ``]'') indicate
optional words or clauses. For example, in the following statement, `IF
EXISTS' is optional:

     DROP TABLE [IF EXISTS] TBL_NAME

When a syntax element consists of a number of alternatives, the
alternatives are separated by vertical bars (``|''). When one member
from a set of choices _may_ be chosen, the alternatives are listed
within square brackets (``['' and ``]''):

     TRIM([[BOTH | LEADING | TRAILING] [REMSTR] FROM] STR)

When one member from a set of choices _must_ be chosen, the
alternatives are listed within braces (``{'' and ``}''):

     {DESCRIBE | DESC} TBL_NAME [COL_NAME | WILD]

An ellipsis (`...') indicates the omission of a section of a statement,
typically to provide a shorter version of more complex syntax. For
example, `SELECT ... INTO OUTFILE' is shorthand for the form of
`SELECT' statement that has an `INTO OUTFILE' clause following other
parts of the statement.

An ellipsis can also indicate that the preceding syntax element of a
statement may be repeated. In the following example, multiple
RESET_OPTION values may be given, with each of those after the first
preceded by commas:

     RESET RESET_OPTION [,RESET_OPTION] ...

Commands for setting shell variables are shown using Bourne shell
syntax. For example, the sequence to set the `CC' environment variable
and run the `configure' command looks like this in Bourne shell syntax:

     shell> CC=gcc ./configure

If you are using `csh' or `tcsh', you must issue commands somewhat
differently:

     shell> setenv CC gcc
     shell> ./configure


File: manual.info,  Node: what-is-mysql-ab,  Next: what-is,  Prev: manual-conventions,  Up: introduction

1.3 Overview of MySQL AB
========================

MySQL AB is the company of the MySQL founders and main developers.
MySQL AB was originally established in Sweden by David Axmark, Allan
Larsson, and Michael `Monty' Widenius.

We are dedicated to developing the MySQL database software and
promoting it to new users. MySQL AB owns the copyright to the MySQL
source code, the MySQL logo and (registered) trademark, and this
manual. See *Note what-is::.

The MySQL core values show our dedication to MySQL and Open Source.

These core values direct how MySQL AB works with the MySQL server
software:

   * To be the best and the most widely used database in the world

   * To be available and affordable by all

   * To be easy to use

   * To be continuously improved while remaining fast and safe

   * To be fun to use and improve

   * To be free from bugs

These are the core values of the company MySQL AB and its employees:

   * We subscribe to the Open Source philosophy and support the Open
     Source community

   * We aim to be good citizens

   * We prefer partners that share our values and mindset

   * We answer email and provide support

   * We are a virtual company, networking with others

   * We work against software patents

The MySQL Web site (`http://www.mysql.com/') provides the latest
information about MySQL and MySQL AB.

By the way, the `AB' part of the company name is the acronym for the
Swedish `aktiebolag,' or `stock company.' It translates to `MySQL,
Inc.' In fact, MySQL, Inc. and MySQL GmbH are examples of MySQL AB
subsidiaries. They are located in the United States and Germany,
respectively.


File: manual.info,  Node: what-is,  Next: roadmap,  Prev: what-is-mysql-ab,  Up: introduction

1.4 Overview of the MySQL Database Management System
====================================================

* Menu:

* what-is-mysql::                What is MySQL?
* history::                      History of MySQL
* features::                     The Main Features of MySQL


File: manual.info,  Node: what-is-mysql,  Next: history,  Prev: what-is,  Up: what-is

1.4.1 What is MySQL?
--------------------

MySQL, the most popular Open Source SQL database management system, is
developed, distributed, and supported by MySQL AB.  MySQL AB is a
commercial company, founded by the MySQL developers.  It is a second
generation Open Source company that unites Open Source values and
methodology with a successful business model.

The MySQL Web site (`http://www.mysql.com/') provides the latest
information about MySQL software and MySQL AB.

   * MySQL is a database management system.

     A database is a structured collection of data. It may be anything
     from a simple shopping list to a picture gallery or the vast
     amounts of information in a corporate network. To add, access, and
     process data stored in a computer database, you need a database
     management system such as MySQL Server.  Since computers are very
     good at handling large amounts of data, database management
     systems play a central role in computing, as standalone utilities,
     or as parts of other applications.

   * MySQL is a relational database management system.

     A relational database stores data in separate tables rather than
     putting all the data in one big storeroom. This adds speed and
     flexibility. The SQL part of `MySQL' stands for `Structured Query
     Language.' SQL is the most common standardized language used to
     access databases and is defined by the ANSI/ISO SQL Standard. The
     SQL standard has been evolving since 1986 and several versions
     exist. In this manual, `SQL-92' refers to the standard released in
     1992, `SQL:1999' refers to the standard released in 1999, and
     `SQL:2003' refers to the current version of the standard. We use
     the phrase `the SQL standard' to mean the current version of the
     SQL Standard at any time.

   * MySQL software is Open Source.

     Open Source means that it is possible for anyone to use and modify
     the software. Anybody can download the MySQL software from the
     Internet and use it without paying anything. If you wish, you may
     study the source code and change it to suit your needs. The MySQL
     software uses the GPL (GNU General Public License),
     `http://www.fsf.org/licenses/', to define what you may and may not
     do with the software in different situations. If you feel
     uncomfortable with the GPL or need to embed MySQL code into a
     commercial application, you can buy a commercially licensed
     version from us. See the MySQL Licensing Overview for more
     information (`http://www.mysql.com/company/legal/licensing/').

   * The MySQL Database Server is very fast, reliable, and easy to use.

     If that is what you are looking for, you should give it a try.
     MySQL Server also has a practical set of features developed in
     close cooperation with our users. You can find a performance
     comparison of MySQL Server with other database managers on our
     benchmark page. See *Note mysql-benchmarks::.

     MySQL Server was originally developed to handle large databases
     much faster than existing solutions and has been successfully used
     in highly demanding production environments for several years.
     Although under constant development, MySQL Server today offers a
     rich and useful set of functions. Its connectivity, speed, and
     security make MySQL Server highly suited for accessing databases
     on the Internet.

   * MySQL Server works in client/server or embedded systems.

     The MySQL Database Software is a client/server system that
     consists of a multi-threaded SQL server that supports different
     backends, several different client programs and libraries,
     administrative tools, and a wide range of application programming
     interfaces (APIs).

     We also provide MySQL Server as an embedded multi-threaded library
     that you can link into your application to get a smaller, faster,
     easier-to-manage standalone product.

   * A large amount of contributed MySQL software is available.

     It is very likely that your favorite application or language
     supports the MySQL Database Server.

The official way to pronounce `MySQL' is `My Ess Que Ell' (not `my
sequel'), but we don't mind if you pronounce it as `my sequel' or in
some other localized way.


File: manual.info,  Node: history,  Next: features,  Prev: what-is-mysql,  Up: what-is

1.4.2 History of MySQL
----------------------

We started out with the intention of using the `mSQL' database system
to connect to our tables using our own fast low-level (ISAM) routines.
However, after some testing, we came to the conclusion that `mSQL' was
not fast enough or flexible enough for our needs. This resulted in a
new SQL interface to our database but with almost the same API
interface as `mSQL'. This API was designed to allow third-party code
that was written for use with `mSQL' to be ported easily for use with
MySQL.

MySQL is named after co-founder Monty Widenius's daughter, My.

The name of the MySQL Dolphin (our logo) is `Sakila,' which was chosen
by the founders of MySQL AB from a huge list of names suggested by
users in our `Name the Dolphin' contest. The winning name was submitted
by Ambrose Twebaze, an Open Source software developer from Swaziland,
Africa. According to Ambrose, the feminine name Sakila has its roots in
SiSwati, the local language of Swaziland. Sakila is also the name of a
town in Arusha, Tanzania, near Ambrose's country of origin, Uganda.


File: manual.info,  Node: features,  Prev: history,  Up: what-is

1.4.3 The Main Features of MySQL
--------------------------------

This section describes some of the important characteristics of the
MySQL Database Software. See also *Note roadmap::, for more information
about current and upcoming features. In most respects, it applies to
all versions of MySQL. For information about features as they are
introduced into MySQL on a series-specific basis, see the `In a
Nutshell' section of the appropriate Manual:

   * MySQL 4.0 and 4.1: MySQL 4.0 in a Nutshell
     (http://dev.mysql.com/doc/refman/4.1/en/mysql-4-0-nutshell.html),
     and MySQL 4.1 in a Nutshell
     (http://dev.mysql.com/doc/refman/4.1/en/mysql-nutshell.html).

   * MySQL 5.0: MySQL 5.0 in a Nutshell
     (http://dev.mysql.com/doc/refman/5.0/en/mysql-nutshell.html).

   * MySQL 5.1: MySQL 5.1 in a Nutshell
     (http://dev.mysql.com/doc/refman/5.1/en/mysql-nutshell.html).

Internals and Portability:

   * Written in C and C++.

   * Tested with a broad range of different compilers.

   * Works on many different platforms. See *Note which-os::.

   * Uses GNU Automake, Autoconf, and Libtool for portability.

   * The MySQL Server design is multi-layered with independent modules.

   * Fully multi-threaded using kernel threads. It can easily use
     multiple CPUs if they are available.

   * Provides transactional and non-transactional storage engines.

   * Uses very fast B-tree disk tables (`MyISAM') with index
     compression.

   * Relatively easy to add other storage engines. This is useful if
     you want to provide an SQL interface for an in-house database.

   * A very fast thread-based memory allocation system.

   * Very fast joins using an optimized one-sweep multi-join.

   * In-memory hash tables, which are used as temporary tables.

   * SQL functions are implemented using a highly optimized class
     library and should be as fast as possible. Usually there is no
     memory allocation at all after query initialization.

   * The MySQL code is tested with Purify (a commercial memory leakage
     detector) as well as with Valgrind, a GPL tool
     (`http://developer.kde.org/~sewardj/').

   * The server is available as a separate program for use in a
     client/server networked environment. It is also available as a
     library that can be embedded (linked) into standalone
     applications. Such applications can be used in isolation or in
     environments where no network is available.

Data Types:

   * Many data types: signed/unsigned integers 1, 2, 3, 4, and 8 bytes
     long, `FLOAT', `DOUBLE', `CHAR', `VARCHAR', `TEXT', `BLOB', `DATE',
     `TIME', `DATETIME', `TIMESTAMP', `YEAR', `SET', `ENUM', and OpenGIS
     spatial types. See *Note data-types::.

   * Fixed-length and variable-length records.

Statements and Functions:

   * Full operator and function support in the `SELECT' list and `WHERE'
     clause of queries. For example:

          mysql> SELECT CONCAT(first_name, ' ', last_name)
              -> FROM citizen
              -> WHERE income/dependents > 10000 AND age > 30;

   * Full support for SQL `GROUP BY' and `ORDER BY' clauses. Support
     for group functions (`COUNT()', `COUNT(DISTINCT ...)', `AVG()',
     `STD()', `SUM()', `MAX()', `MIN()', and `GROUP_CONCAT()').

   * Support for `LEFT OUTER JOIN' and `RIGHT OUTER JOIN' with both
     standard SQL and ODBC syntax.

   * Support for aliases on tables and columns as required by standard
     SQL.

   * `DELETE', `INSERT', `REPLACE', and `UPDATE' return the number of
     rows that were changed (affected). It is possible to return the
     number of rows matched instead by setting a flag when connecting
     to the server.

   * The MySQL-specific `SHOW' statement can be used to retrieve
     information about databases, storage engines, tables, and indexes.
     MySQL 5.0 adds support for the `INFORMATION_SCHEMA' database,
     implemented according to standard SQL.

   * The `EXPLAIN' statement can be used to determine how the optimizer
     resolves a query.

   * Function names do not clash with table or column names. For
     example, `ABS' is a valid column name. The only restriction is
     that for a function call, no spaces are allowed between the
     function name and the ``('' that follows it. See *Note
     reserved-words::.

   * You can refer to tables from different databases in the same
     statement.

Security:

   * A privilege and password system that is very flexible and secure,
     and that allows host-based verification.

   * Passwords are secure because all password traffic is encrypted
     when you connect to a server.

Scalability and Limits:

   * Handles large databases. We use MySQL Server with databases that
     contain 50 million records. We also know of users who use MySQL
     Server with 60,000 tables and about 5,000,000,000 rows.

   * Up to 64 indexes per table are allowed (32 before MySQL 4.1.2).
     Each index may consist of 1 to 16 columns or parts of columns. The
     maximum index width is 1000 bytes (767 for `InnoDB'); before MySQL
     4.1.2, the limit is 500 bytes. An index may use a prefix of a
     column for `CHAR', `VARCHAR', `BLOB', or `TEXT' column types.

Connectivity:

   * Clients can connect to MySQL Server using several protocols:

        * Clients can connect using TCP/IP sockets on any platform.

        * On Windows systems in the NT family (NT, 2000, XP, 2003, or
          Vista), clients can connect using named pipes if the server
          is started with the `--enable-named-pipe' option. In MySQL 4.1
          and higher, Windows servers also support shared-memory
          connections if started with the `--shared-memory' option.
          Clients can connect through shared memory by using the
          `--protocol=memory' option.

        * On Unix systems, clients can connect using Unix domain socket
          files.

   * MySQL client programs can be written in many languages. A client
     library written in C is available for clients written in C or C++,
     or for any language that provides C bindings.

   * APIs for C, C++, Eiffel, Java, Perl, PHP, Python, Ruby, and Tcl
     are available, allowing MySQL clients to be written in many
     languages. See *Note apis::.

   * The Connector/ODBC (MyODBC) interface provides MySQL support for
     client programs that use ODBC (Open Database Connectivity)
     connections. For example, you can use MS Access to connect to your
     MySQL server. Clients can be run on Windows or Unix.  MyODBC
     source is available. All ODBC 2.5 functions are supported, as are
     many others. See *Note connectors::.

   * The Connector/J interface provides MySQL support for Java client
     programs that use JDBC connections. Clients can be run on Windows
     or Unix. Connector/J source is available. See *Note connectors::.

   * MySQL Connector/NET enables developers to easily create .NET
     applications that require secure, high-performance data
     connectivity with MySQL. It implements the required ADO.NET
     interfaces and integrates into ADO.NET aware tools. Developers can
     build applications using their choice of .NET languages.  MySQL
     Connector/NET is a fully managed ADO.NET driver written in 100%
     pure C#. See *Note connectors::.

Localization:

   * The server can provide error messages to clients in many
     languages. See *Note error-message-language::.

   * Full support for several different character sets, including
     `latin1' (cp1252), `german', `big5', `ujis', and more.  For
     example, the Scandinavian characters ``aa'', ``a"'' and ``o"'' are
     allowed in table and column names. Unicode support is available as
     of MySQL 4.1.

   * All data is saved in the chosen character set.

   * Sorting and comparisons are done according to the chosen character
     set and collation (using `latin1' and Swedish collation by
     default). It is possible to change this when the MySQL server is
     started. To see an example of very advanced sorting, look at the
     Czech sorting code. MySQL Server supports many different character
     sets that can be specified at compile time and runtime.

   * As of MySQL 4.1, the server time zone can be changed dynamically,
     and individual clients can specify their own time zone. *Note
     time-zone-support::.

MySQL Enterprise

For assistance in getting optimal performance from your MySQL server
subscribe to MySQL Enterprise. For more information see
`http://www.mysql.com/products/enterprise/'.

Clients and Tools:

   * MySQL AB provides several client and utility programs. These
     include both command-line programs such as `mysqldump' and
     `mysqladmin', and graphical programs such as MySQL Administrator
     and MySQL Query Browser.

   * MySQL Server has built-in support for SQL statements to check,
     optimize, and repair tables. These statements are available from
     the command line through the `mysqlcheck' client. MySQL also
     includes `myisamchk', a very fast command-line utility for
     performing these operations on `MyISAM' tables. See *Note
     programs::.

   * MySQL programs can be invoked with the `--help' or `-?' option to
     obtain online assistance.


File: manual.info,  Node: roadmap,  Next: information-sources,  Prev: what-is,  Up: introduction

1.5 MySQL Development Roadmap
=============================

* Menu:

* mysql-nutshell::               What's New in MySQL 5.1
* mysql-6-0-plans::              What's Planned for MySQL 6.0

This section describes the general MySQL development roadmap, provides
an overview about features that have been implemented in previous
series and that are new in this current release series (5.1), and an
overview about upcoming additions or changes in the next release series
(6.0).

The maturity level of the release series covered in this manual (5.1)
is release candidate. Information about maturity levels can be found in
*Note choosing-version::.

Before upgrading from one release series to the next, please see the
notes in *Note upgrade::.

The most requested features and the versions in which they were
implemented or are scheduled for implementation are summarized in the
following table:

*Feature*              *MySQL Series*
Unions                 4.0
Subqueries             4.1
R-trees                4.1 (for the `MyISAM' storage engine)
Stored procedures      5.0
Views                  5.0
Cursors                5.0
XA transactions        5.0
Triggers               5.0 and 5.1
Event scheduler        5.1
Partitioning           5.1
Pluggable storage      5.1
engine API             
Plugin API             5.1
Row-based replication  5.1
Server log tables      5.1
Foreign keys           6.x (implemented in 3.23 for `InnoDB')


File: manual.info,  Node: mysql-nutshell,  Next: mysql-6-0-plans,  Prev: roadmap,  Up: roadmap

1.5.1 What's New in MySQL 5.1
-----------------------------

The following features have been added to MySQL 5.1.

   * Partitioning

     This capability enables distributing portions of individual tables
     across a filesystem, according to rules which can be set when the
     table is created. In effect, different portions of a table are
     stored as separate tables in different locations, but from the
     user point of view, the partitioned table is still a single table.
     Syntactically, this implements a number of new extensions to the
     `CREATE TABLE', `ALTER TABLE', and `EXPLAIN ... SELECT'
     statements. As of MySQL 5.1.6, queries against partitioned tables
     can take advantage of _partition pruning_. In some cases, this can
     result in query execution that is an order of magnitude faster than
     the same query against a non-partitioned version of the same
     table. See *Note partitioning::, for further information on this
     functionality. (Author: Mikael Ronstro"m)

   * Row-based replication

     Replication capabilities in MySQL originally were based on
     propagation of SQL statements from master to slave. This is called
     _statement-based replication_. As of MySQL 5.1.5, another basis
     for replication is available. This is called _row-based
     replication_. Instead of sending SQL statements to the slave, the
     master writes events to its binary log that indicate how individual
     table rows are effected. As of MySQL 5.1.8, a third option is
     available: _mixed_. This will use statement-based replication by
     default, and only switch to row-based replication in particular
     cases. See *Note replication-formats::. (Authors: Lars Thalmann,
     Guilhem Bichot, Mats Kindahl)

   * Plugin API

     MySQL 5.1 adds support for a very flexible plugin API that enables
     loading and unloading of various components at runtime, without
     restarting the server. Although the work on this is not finished
     yet, _plugin full-text parsers_ are a first step in this direction.
     This allows users to implement their own input filter on the
     indexed text, enabling full-text search capability on arbitrary
     data such as PDF files or other document formats. A pre-parser
     full-text plugin performs the actual parsing and extraction of the
     text and hands it over to the built-in MySQL full-text search. See
     *Note plugin-api::. (Author: Sergey Vojtovich)

   * Event scheduler

     MySQL Events are tasks that run according to a schedule.  When you
     create an event, you are creating a named database object
     containing one or more SQL statements to be executed at one or
     more regular intervals, beginning and ending at a specific date
     and time. Conceptually, this is similar to the idea of the Unix
     `crontab' (also known as a `cron job') or the Windows Task
     Scheduler. See *Note events::. (Author: Andrey Hristov)

   * Server log tables

     Before MySQL 5.1, the server writes general query log and slow
     query log entries to log files. As of MySQL 5.1, the server's
     logging capabilities for these logs are more flexible. Log entries
     can be written to log files (as before) or to the `general_log' and
     `slow_log' tables in the `mysql' database. If logging is enabled,
     either or both destinations can be selected. The `--log-output'
     option controls the destination or destinations of log output. See
     *Note log-tables::. (Author: Petr Chardin)

   * Upgrade program

     The `mysql_upgrade' program (available as of MySQL 5.1.7) checks
     all existing tables for incompatibilities with the current version
     of MySQL Server and repairs them if necessary. This program should
     be run for each MySQL upgrade. See *Note mysql-upgrade::.
     (Authors: Alexey Botchkov, Mikael Widenius)

   * MySQL Cluster replication

     Replication between MySQL Clusters is now supported. It is now
     also possible to replicate between a MySQL Cluster and a
     non-cluster database. See *Note mysql-cluster-replication::.

   * MySQL Cluster disk data storage

     In MySQL versions previous to 5.1.6, the `NDBCLUSTER' storage
     engine was strictly in-memory; beginning with MySQL 5.1.6, it is
     possible to store Cluster data (but not indexes) on disk. This
     allows MySQL Cluster to scale upward with fewer hardware (RAM)
     requirements than previously. In addition, the Disk Data
     implementation includes a new `no-steal' restoration algorithm for
     fast node restarts when storing very large amounts of data
     (terabyte range). See *Note mysql-cluster-disk-data::.

   * Improved backups for MySQL Cluster

     A fault arising in a single data node during a Cluster backup no
     longer causes the entire backup to be aborted, as occurred in
     previous versions of MySQL Cluster.

   * MySQL Cluster NDB 6.x

     Many new features and other improvements have been made to the
     `NDBCLUSTER' storage engine in MySQL Cluster NDB 6.x (formerly
     known as `MySQL Cluster Carrier Grade Edition'); for an overview
     of these, see *Note mysql-cluster-roadmap::.

   * Backup of tablespaces

     The `mysqldump' utility now supports an option for dumping
     tablespaces. Use `-Y' or `--all-tablespaces' to enable this
     functionality.

   * Improvements to `INFORMATION_SCHEMA'

     MySQL 5.1 provides much more information in its metadata database
     than was available in MySQL 5.0. New tables in the
     `INFORMATION_SCHEMA' database include `FILES', `EVENTS',
     `PARTITIONS', `PROCESSLIST', `ENGINES', and `PLUGINS'.

   * XML functions with XPath support

     `ExtractValue()' returns the content of a fragment of XML matching
     a given XPath expression. `UpdateXML()' replaces the element
     selected from a fragment of XML by an XPath expression supplied by
     the user with a second XML fragment (also user-supplied), and
     returns the modified XML. See *Note xml-functions::. (Author:
     Alexander Barkov)

   * Load emulator

     The `mysqlslap' program is designed to emulate client load for a
     MySQL server and report the timing of each stage. It works as if
     multiple clients were accessing the server. See *Note mysqlslap::.
     (Authors: Patrick Galbraith, Brian Aker)


File: manual.info,  Node: mysql-6-0-plans,  Prev: mysql-nutshell,  Up: roadmap

1.5.2 What's Planned for MySQL 6.0
----------------------------------

*Note*:

This section remains subject to change as long as MySQL 6.0 development
is in its early stages.

The following features will be added to MySQL 6.0, or change in MySQL
6.0:

   * A new transactional storage engine (`Falcon').

   * Support for additional Unicode character sets: `utf16', `utf32',
     and 4-byte `utf8'. These character sets support supplementary
     Unicode characters; that is, characters outside the Basic
     Multilingual Plane (BMP).

   * `BACKUP DATABASE' and `RESTORE' statements for backup and restore
     operations.

   * Improvements in the `INFORMATION_SCHEMA' database, with the
     addition of the `INFORMATION_SCHEMA.PARAMETERS' table, and new
     columns added to `INFORMATION_SCHEMA.ROUTINES'.

   * Optimizer enhancements for faster subqueries and joins, including
     batched index access of table rows for sequences of disjoint
     ranges by the `MyISAM' and `InnoDB' storage engines.

   * `RESET SLAVE' no longer changes replication connection parameters.
     Previously, it reset them to the values specified on the command
     line.

   * The syntax for the `LOCK TABLES' statement is extended to support
     transactional table locks that do not commit transactions
     automatically. Following `LOCK TABLES ... IN SHARE MODE' or `LOCK
     TABLES ... IN EXCLUSIVE MODE', you can access tables not mentioned
     in the `LOCK TABLES' statement. You can now also issue these
     extended `LOCK TABLES' statements many times in succession, adding
     additional tables to the locked set, and without unlocking any
     tables that were locked previously. When using `LOCK TABLES' with
     `IN SHARE MODE' or `IN EXCLUSIVE MODE', tables are not unlocked
     until the transaction ends.

     The behavior of `LOCK TABLES' when not using `IN SHARE MODE' or `IN
     EXCLUSIVE MODE' remains unchanged.

   * Further enhancements to XML functionality, including a new `LOAD
     XML' statement.

   * Support for extended comments for tables, columns, and indexes.

The following constructs are deprecated and have been removed for MySQL
6.0 (they were actually removed in 5.2.5). Where alternatives are
shown, applications should be updated to use them.

   * The `table_type' system variable (use `storage_engine').

     The `TYPE' table option to specify the storage engine for `CREATE
     TABLE' or `ALTER TABLE' (use `ENGINE').

     The `SHOW TABLE TYPES' SQL statement (use `SHOW ENGINES').

   * The `log_bin_trust_routine_creators' variable (use
     `log_bin_trust_function_creators').

   * `TIMESTAMP(N)': The ability to specify a display width of N (use
     without N).

   * The `SHOW INNODB STATUS' and `SHOW MUTEX STATUS' SQL statements
     (use `SHOW ENGINE INNODB STATUS' for both of these).

   * The `LOAD TABLE ... FROM MASTER' and `LOAD DATA FROM MASTER' SQL
     statements.

   * The `SHOW PLUGIN' SQL statement (use `SHOW PLUGINS').

   * The `RESTORE TABLE' SQL statement.

   * The `BACKUP TABLE' SQL statement.

   * The `--master-XXX' server options to set replication parameters
     (use the `CHANGE MASTER' statement).


File: manual.info,  Node: information-sources,  Next: bug-reports,  Prev: roadmap,  Up: introduction

1.6 MySQL Information Sources
=============================

* Menu:

* mailing-lists::                MySQL Mailing Lists
* forums::                       MySQL Community Support at the MySQL Forums
* irc::                          MySQL Community Support on Internet Relay Chat (IRC)
* mysql-enterprise-information::  MySQL Enterprise

This section lists sources of additional information that you may find
helpful, such as the MySQL mailing lists and user forums, and Internet
Relay Chat.


File: manual.info,  Node: mailing-lists,  Next: forums,  Prev: information-sources,  Up: information-sources

1.6.1 MySQL Mailing Lists
-------------------------

* Menu:

* mailing-list-use::             Guidelines for Using the Mailing Lists

This section introduces the MySQL mailing lists and provides guidelines
as to how the lists should be used. When you subscribe to a mailing
list, you receive all postings to the list as email messages. You can
also send your own questions and answers to the list.

To subscribe to or unsubscribe from any of the mailing lists described
in this section, visit `http://lists.mysql.com/'. For most of them, you
can select the regular version of the list where you get individual
messages, or a digest version where you get one large message per day.

Please _do not_ send messages about subscribing or unsubscribing to any
of the mailing lists, because such messages are distributed
automatically to thousands of other users.

Your local site may have many subscribers to a MySQL mailing list.  If
so, the site may have a local mailing list, so that messages sent from
`lists.mysql.com' to your site are propagated to the local list. In
such cases, please contact your system administrator to be added to or
dropped from the local MySQL list.

If you wish to have traffic for a mailing list go to a separate mailbox
in your mail program, set up a filter based on the message headers. You
can use either the `List-ID:' or `Delivered-To:' headers to identify
list messages.

The MySQL mailing lists are as follows:

   * `announce'

     This list is for announcements of new versions of MySQL and
     related programs. This is a low-volume list to which all MySQL
     users should subscribe.

   * `mysql'

     This is the main list for general MySQL discussion. Please note
     that some topics are better discussed on the more-specialized
     lists. If you post to the wrong list, you may not get an answer.

   * `bugs'

     This list is for people who want to stay informed about issues
     reported since the last release of MySQL or who want to be
     actively involved in the process of bug hunting and fixing.  See
     *Note bug-reports::.

   * `internals'

     This list is for people who work on the MySQL code. This is also
     the forum for discussions on MySQL development and for posting
     patches.

   * `mysqldoc'

     This list is for people who work on the MySQL documentation:
     people from MySQL AB, translators, and other community members.

   * `benchmarks'

     This list is for anyone interested in performance issues.
     Discussions concentrate on database performance (not limited to
     MySQL), but also include broader categories such as performance of
     the kernel, filesystem, disk system, and so on.

   * `packagers'

     This list is for discussions on packaging and distributing MySQL.
     This is the forum used by distribution maintainers to exchange
     ideas on packaging MySQL and on ensuring that MySQL looks and
     feels as similar as possible on all supported platforms and
     operating systems.

   * `java'

     This list is for discussions about the MySQL server and Java.  It
     is mostly used to discuss JDBC drivers such as MySQL Connector/J.

   * `win32'

     This list is for all topics concerning the MySQL software on
     Microsoft operating systems, such as Windows 9x, Me, NT, 2000, XP,
     and 2003.

   * `myodbc'

     This list is for all topics concerning connecting to the MySQL
     server with ODBC.

   * `gui-tools'

     This list is for all topics concerning MySQL graphical user
     interface tools such as `MySQL Administrator' and `MySQL Query
     Browser'.

   * `cluster'

     This list is for discussion of MySQL Cluster.

   * `dotnet'

     This list is for discussion of the MySQL server and the .NET
     platform. It is mostly related to MySQL Connector/Net.

   * `plusplus'

     This list is for all topics concerning programming with the C++
     API for MySQL.

   * `perl'

     This list is for all topics concerning Perl support for MySQL with
     `DBD::mysql'.

If you're unable to get an answer to your questions from a MySQL
mailing list or forum, one option is to purchase support from MySQL AB.
This puts you in direct contact with MySQL developers.

The following table shows some MySQL mailing lists in languages other
than English. These lists are not operated by MySQL AB.

   * `<mysql-france-subscribe@yahoogroups.com>'

     A French mailing list.

   * `<list@tinc.net>'

     A Korean mailing list. To subscribe, email `subscribe mysql
     your@email.address' to this list.

   * `<mysql-de-request@lists.4t2.com>'

     A German mailing list. To subscribe, email `subscribe mysql-de
     your@email.address' to this list. You can find information about
     this mailing list at `http://www.4t2.com/mysql/'.

   * `<mysql-br-request@listas.linkway.com.br>'

     A Portuguese mailing list. To subscribe, email `subscribe mysql-br
     your@email.address' to this list.

   * `<mysql-alta@elistas.net>'

     A Spanish mailing list. To subscribe, email `subscribe mysql
     your@email.address' to this list.


File: manual.info,  Node: mailing-list-use,  Prev: mailing-lists,  Up: mailing-lists

1.6.1.1 Guidelines for Using the Mailing Lists
..............................................

Please don't post mail messages from your browser with HTML mode turned
on. Many users don't read mail with a browser.

When you answer a question sent to a mailing list, if you consider your
answer to have broad interest, you may want to post it to the list
instead of replying directly to the individual who asked. Try to make
your answer general enough that people other than the original poster
may benefit from it.  When you post to the list, please make sure that
your answer is not a duplication of a previous answer.

Try to summarize the essential part of the question in your reply.
Don't feel obliged to quote the entire original message.

When answers are sent to you individually and not to the mailing list,
it is considered good etiquette to summarize the answers and send the
summary to the mailing list so that others may have the benefit of
responses you received that helped you solve your problem.


File: manual.info,  Node: forums,  Next: irc,  Prev: mailing-lists,  Up: information-sources

1.6.2 MySQL Community Support at the MySQL Forums
-------------------------------------------------

The forums at `http://forums.mysql.com' are an important community
resource. Many forums are available, grouped into these general
categories:

   * Migration

   * MySQL Usage

   * MySQL Connectors

   * Programming Languages

   * Tools

   * 3rd-Party Applications

   * Storage Engines

   * MySQL Technology

   * SQL Standards

   * Business


File: manual.info,  Node: irc,  Next: mysql-enterprise-information,  Prev: forums,  Up: information-sources

1.6.3 MySQL Community Support on Internet Relay Chat (IRC)
----------------------------------------------------------

In addition to the various MySQL mailing lists and forums, you can find
experienced community people on Internet Relay Chat (IRC).  These are
the best networks/channels currently known to us:

*freenode* (see `http://www.freenode.net/' for servers)

   * `#mysql' is primarily for MySQL questions, but other database and
     general SQL questions are welcome.  Questions about PHP, Perl, or
     C in combination with MySQL are also common.

If you are looking for IRC client software to connect to an IRC
network, take a look at `xChat' (`http://www.xchat.org/'). X-Chat (GPL
licensed) is available for Unix as well as for Windows platforms (a free
Windows build of X-Chat is available at
`http://www.silverex.org/download/').


File: manual.info,  Node: mysql-enterprise-information,  Prev: irc,  Up: information-sources

1.6.4 MySQL Enterprise
----------------------

MySQL AB offers technical support in the form of MySQL Enterprise.  For
organizations that rely on the MySQL DBMS for business-critical
production applications, MySQL Enterprise is a commercial subscription
offering which includes:

   * MySQL Enterprise Server

   * MySQL Enterprise Monitor

   * Monthly Rapid Updates and Quarterly Service Packs

   * MySQL Knowledge Base

   * 24x7 Technical and Consultative Support

MySQL Enterprise is available in multiple tiers, giving you the
flexibility to choose the level of service that best matches your
needs. For more information see MySQL Enterprise
(http://www.mysql.com/products/enterprise/).


File: manual.info,  Node: bug-reports,  Next: compatibility,  Prev: information-sources,  Up: introduction

1.7 How to Report Bugs or Problems
==================================

Before posting a bug report about a problem, please try to verify that
it is a bug and that it has not been reported already:

   * Start by searching the MySQL online manual at
     `http://dev.mysql.com/doc/'. We try to keep the manual up to date
     by updating it frequently with solutions to newly found problems.
     The change history (`http://dev.mysql.com/doc/mysql/en/news.html')
     can be particularly useful since it is quite possible that a newer
     version contains a solution to your problem.

   * If you get a parse error for a SQL statement, please check your
     syntax closely. If you can't find something wrong with it, it's
     extremely likely that your current version of MySQL Server doesn't
     support the syntax you are using. If you are using the current
     version and the manual doesn't cover the syntax that you are
     using, MySQL Server doesn't support your statement. In this case,
     your options are to implement the syntax yourself or email
     <licensing@mysql.com> and ask for an offer to implement it.

     If the manual covers the syntax you are using, but you have an
     older version of MySQL Server, you should check the MySQL change
     history to see when the syntax was implemented. In this case, you
     have the option of upgrading to a newer version of MySQL Server.

   * For solutions to some common problems, see *Note problems::.

   * Search the bugs database at `http://bugs.mysql.com/' to see
     whether the bug has been reported and fixed.

   * Search the MySQL mailing list archives at
     `http://lists.mysql.com/'. See *Note mailing-lists::.

   * You can also use `http://www.mysql.com/search/' to search all the
     Web pages (including the manual) that are located at the MySQL AB
     Web site.

If you can't find an answer in the manual, the bugs database, or the
mailing list archives, check with your local MySQL expert. If you still
can't find an answer to your question, please use the following
guidelines for reporting the bug.

The normal way to report bugs is to visit `http://bugs.mysql.com/',
which is the address for our bugs database. This database is public and
can be browsed and searched by anyone. If you log in to the system, you
can enter new reports. If you have no Web access, you can generate a
bug report by using the `mysqlbug' script described at the end of this
section.

Bugs posted in the bugs database at `http://bugs.mysql.com/' that are
corrected for a given release are noted in the change history.

If you have found a sensitive security bug in MySQL, you can send email
to <security@mysql.com>.

To discuss problems with other users, you can use one of the MySQL
mailing lists. *Note mailing-lists::.

Writing a good bug report takes patience, but doing it right the first
time saves time both for us and for yourself. A good bug report,
containing a full test case for the bug, makes it very likely that we
will fix the bug in the next release. This section helps you write your
report correctly so that you don't waste your time doing things that
may not help us much or at all. Please read this section carefully and
make sure that all the information described here is included in your
report.

Preferably, you should test the problem using the latest production or
development version of MySQL Server before posting. Anyone should be
able to repeat the bug by just using `mysql test < script_file' on your
test case or by running the shell or Perl script that you include in
the bug report. Any bug that we are able to repeat has a high chance of
being fixed in the next MySQL release.

It is most helpful when a good description of the problem is included
in the bug report. That is, give a good example of everything you did
that led to the problem and describe, in exact detail, the problem
itself. The best reports are those that include a full example showing
how to reproduce the bug or problem. See MySQL Internals: Porting
(http://forge.mysql.com/wiki/MySQL_Internals_Porting).

Remember that it is possible for us to respond to a report containing
too much information, but not to one containing too little. People
often omit facts because they think they know the cause of a problem
and assume that some details don't matter. A good principle to follow
is that if you are in doubt about stating something, state it. It is
faster and less troublesome to write a couple more lines in your report
than to wait longer for the answer if we must ask you to provide
information that was missing from the initial report.

The most common errors made in bug reports are (a) not including the
version number of the MySQL distribution that you use, and (b) not
fully describing the platform on which the MySQL server is installed
(including the platform type and version number). These are highly
relevant pieces of information, and in 99 cases out of 100, the bug
report is useless without them. Very often we get questions like, `Why
doesn't this work for me?' Then we find that the feature requested
wasn't implemented in that MySQL version, or that a bug described in a
report has been fixed in newer MySQL versions.  Errors often are
platform-dependent. In such cases, it is next to impossible for us to
fix anything without knowing the operating system and the version
number of the platform.

If you compiled MySQL from source, remember also to provide information
about your compiler if it is related to the problem.  Often people find
bugs in compilers and think the problem is MySQL-related. Most
compilers are under development all the time and become better version
by version. To determine whether your problem depends on your compiler,
we need to know what compiler you used.  Note that every compiling
problem should be regarded as a bug and reported accordingly.

If a program produces an error message, it is very important to include
the message in your report. If we try to search for something from the
archives, it is better that the error message reported exactly matches
the one that the program produces. (Even the lettercase should be
observed.) It is best to copy and paste the entire error message into
your report. You should never try to reproduce the message from memory.

If you have a problem with Connector/ODBC (MyODBC), please try to
generate a trace file and send it with your report. See the MyODBC
section of *Note connectors::.

If your report includes long query output lines from test cases that
you run with the `mysql' command-line tool, you can make the output
more readable by using the `--vertical' option or the `\G' statement
terminator. The `EXPLAIN SELECT' example later in this section
demonstrates the use of `\G'.

Please include the following information in your report:

   * The version number of the MySQL distribution you are using (for
     example, MySQL 5.0.19). You can find out which version you are
     running by executing `mysqladmin version'. The `mysqladmin'
     program can be found in the `bin' directory under your MySQL
     installation directory.

   * The manufacturer and model of the machine on which you experience
     the problem.

   * The operating system name and version. If you work with Windows,
     you can usually get the name and version number by double-clicking
     your My Computer icon and pulling down the `Help/About Windows'
     menu. For most Unix-like operating systems, you can get this
     information by executing the command `uname -a'.

   * Sometimes the amount of memory (real and virtual) is relevant.  If
     in doubt, include these values.

   * If you are using a source distribution of the MySQL software,
     include the name and version number of the compiler that you used.
     If you have a binary distribution, include the distribution name.

   * If the problem occurs during compilation, include the exact error
     messages and also a few lines of context around the offending code
     in the file where the error occurs.

   * If `mysqld' died, you should also report the statement that
     crashed `mysqld'. You can usually get this information by running
     `mysqld' with query logging enabled, and then looking in the log
     after `mysqld' crashes. See MySQL Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

   * If a database table is related to the problem, include the output
     from the `SHOW CREATE TABLE DB_NAME.TBL_NAME' statement in the bug
     report. This is a very easy way to get the definition of any table
     in a database. The information helps us create a situation
     matching the one that you have experienced.

   * The SQL mode in effect when the problem occurred can be
     significant, so please report the value of the `sql_mode' system
     variable. For stored procedure, stored function, and trigger
     objects, the relevant `sql_mode' value is the one in effect when
     the object was created. For a stored procedure or function, the
     `SHOW CREATE PROCEDURE' or `SHOW CREATE FUNCTION' statement shows
     the relevant SQL mode, or you can query `INFORMATION_SCHEMA' for
     the information:

          SELECT ROUTINE_SCHEMA, ROUTINE_NAME, SQL_MODE
          FROM INFORMATION_SCHEMA.ROUTINES;

     For triggers, you can use this statement:

          SELECT EVENT_OBJECT_SCHEMA, EVENT_OBJECT_TABLE, TRIGGER_NAME, SQL_MODE
          FROM INFORMATION_SCHEMA.TRIGGERS;

   * For performance-related bugs or problems with `SELECT' statements,
     you should always include the output of `EXPLAIN SELECT ...', and
     at least the number of rows that the `SELECT' statement produces.
     You should also include the output from `SHOW CREATE TABLE
     TBL_NAME' for each table that is involved. The more information
     you provide about your situation, the more likely it is that
     someone can help you.

     The following is an example of a very good bug report. The
     statements are run using the `mysql' command-line tool. Note the
     use of the `\G' statement terminator for statements that would
     otherwise provide very long output lines that are difficult to
     read.

          mysql> SHOW VARIABLES;
          mysql> SHOW COLUMNS FROM ...\G
                 <OUTPUT FROM SHOW COLUMNS>
          mysql> EXPLAIN SELECT ...\G
                 <OUTPUT FROM EXPLAIN>
          mysql> FLUSH STATUS;
          mysql> SELECT ...;
                 <A SHORT VERSION OF THE OUTPUT FROM SELECT,
                 INCLUDING THE TIME TAKEN TO RUN THE QUERY>
          mysql> SHOW STATUS;
                 <OUTPUT FROM SHOW STATUS>

   * If a bug or problem occurs while running `mysqld', try to provide
     an input script that reproduces the anomaly. This script should
     include any necessary source files. The more closely the script
     can reproduce your situation, the better. If you can make a
     reproducible test case, you should upload it to be attached to the
     bug report.

     If you can't provide a script, you should at least include the
     output from `mysqladmin variables extended-status processlist' in
     your report to provide some information on how your system is
     performing.

   * If you can't produce a test case with only a few rows, or if the
     test table is too big to be included in the bug report (more than
     10 rows), you should dump your tables using `mysqldump' and create
     a `README' file that describes your problem.  Create a compressed
     archive of your files using `tar' and `gzip' or `zip', and use FTP
     to transfer the archive to
     `ftp://ftp.mysql.com/pub/mysql/upload/'. Then enter the problem
     into our bugs database at `http://bugs.mysql.com/'.

   * If you believe that the MySQL server produces a strange result
     from a statement, include not only the result, but also your
     opinion of what the result should be, and an explanation
     describing the basis for your opinion.

   * When you provide an example of the problem, it's better to use the
     table names, variable names, and so forth that exist in your
     actual situation than to come up with new names. The problem could
     be related to the name of a table or variable. These cases are
     rare, perhaps, but it is better to be safe than sorry. After all,
     it should be easier for you to provide an example that uses your
     actual situation, and it is by all means better for us. If you
     have data that you don't want to be visible to others in the bug
     report, you can use FTP to transfer it to
     `ftp://ftp.mysql.com/pub/mysql/upload/'. If the information is
     really top secret and you don't want to show it even to us, go
     ahead and provide an example using other names, but please regard
     this as the last choice.

   * Include all the options given to the relevant programs, if
     possible. For example, indicate the options that you use when you
     start the `mysqld' server, as well as the options that you use to
     run any MySQL client programs. The options to programs such as
     `mysqld' and `mysql', and to the `configure' script, are often key
     to resolving problems and are very relevant. It is never a bad
     idea to include them. If your problem involves a program written
     in a language such as Perl or PHP, please include the language
     processor's version number, as well as the version for any modules
     that the program uses. For example, if you have a Perl script that
     uses the `DBI' and `DBD::mysql' modules, include the version
     numbers for Perl, `DBI', and `DBD::mysql'.

   * If your question is related to the privilege system, please
     include the output of `mysqlaccess', the output of `mysqladmin
     reload', and all the error messages you get when trying to
     connect. When you test your privileges, you should first run
     `mysqlaccess'.  After this, execute `mysqladmin reload version'
     and try to connect with the program that gives you trouble.
     `mysqlaccess' can be found in the `bin' directory under your MySQL
     installation directory.

   * If you have a patch for a bug, do include it. But don't assume
     that the patch is all we need, or that we can use it, if you don't
     provide some necessary information such as test cases showing the
     bug that your patch fixes. We might find problems with your patch
     or we might not understand it at all. If so, we can't use it.

     If we can't verify the exact purpose of the patch, we won't use
     it. Test cases help us here. Show that the patch handles all the
     situations that may occur. If we find a borderline case (even a
     rare one) where the patch won't work, it may be useless.

   * Guesses about what the bug is, why it occurs, or what it depends
     on are usually wrong. Even the MySQL team can't guess such things
     without first using a debugger to determine the real cause of a
     bug.

   * Indicate in your bug report that you have checked the reference
     manual and mail archive so that others know you have tried to
     solve the problem yourself.

   * If the problem is that your data appears corrupt or you get errors
     when you access a particular table, you should first check your
     tables and then try to repair them with `CHECK TABLE' and `REPAIR
     TABLE' or with `myisamchk'. See *Note server-administration::.

     If you are running Windows, please verify the value of
     `lower_case_table_names' using the `SHOW VARIABLES LIKE
     'lower_case_table_names'' command. This variable affects how the
     server handles lettercase of database and table names. Its effect
     for a given value should be as described in *Note
     identifier-case-sensitivity::.

   * If you often get corrupted tables, you should try to find out when
     and why this happens. In this case, the error log in the MySQL
     data directory may contain some information about what happened.
     (This is the file with the `.err' suffix in the name.) See *Note
     error-log::. Please include any relevant information from this
     file in your bug report. Normally `mysqld' should _never_ crash a
     table if nothing killed it in the middle of an update. If you can
     find the cause of `mysqld' dying, it's much easier for us to
     provide you with a fix for the problem. See *Note
     what-is-crashing::.

   * If possible, download and install the most recent version of MySQL
     Server and check whether it solves your problem. All versions of
     the MySQL software are thoroughly tested and should work without
     problems. We believe in making everything as backward-compatible
     as possible, and you should be able to switch MySQL versions
     without difficulty. See *Note which-version::.

If you have no Web access and cannot report a bug by visiting
`http://bugs.mysql.com/', you can use the `mysqlbug' script to generate
a bug report (or a report about any problem). `mysqlbug' helps you
generate a report by determining much of the following information
automatically, but if something important is missing, please include it
with your message. `mysqlbug' can be found in the `scripts' directory
(source distribution) and in the `bin' directory under your MySQL
installation directory (binary distribution).


File: manual.info,  Node: compatibility,  Prev: bug-reports,  Up: introduction

1.8 MySQL Standards Compliance
==============================

* Menu:

* standards::                    What Standards MySQL Follows
* sql-mode::                     Selecting SQL Modes
* ansi-mode::                    Running MySQL in ANSI Mode
* extensions-to-ansi::           MySQL Extensions to Standard SQL
* differences-from-ansi::        MySQL Differences from Standard SQL
* constraints::                  How MySQL Deals with Constraints

This section describes how MySQL relates to the ANSI/ISO SQL standards.
MySQL Server has many extensions to the SQL standard, and here you can
find out what they are and how to use them. You can also find
information about functionality missing from MySQL Server, and how to
work around some of the differences.

The SQL standard has been evolving since 1986 and several versions
exist. In this manual, `SQL-92' refers to the standard released in
1992, `SQL:1999' refers to the standard released in 1999, `SQL:2003'
refers to the standard released in 2003, and `SQL:2008' refers to the
most recent version of the standard, released in 2008. We use the
phrase `the SQL standard' or `standard SQL' to mean the current version
of the SQL Standard at any time.

One of our main goals with the product is to continue to work toward
compliance with the SQL standard, but without sacrificing speed or
reliability. We are not afraid to add extensions to SQL or support for
non-SQL features if this greatly increases the usability of MySQL
Server for a large segment of our user base.  The `HANDLER' interface
is an example of this strategy. See *Note handler::.

We continue to support transactional and non-transactional databases to
satisfy both mission-critical 24/7 usage and heavy Web or logging usage.

MySQL Server was originally designed to work with medium-sized
databases (10-100 million rows, or about 100MB per table) on small
computer systems. Today MySQL Server handles terabyte-sized databases,
but the code can also be compiled in a reduced version suitable for
hand-held and embedded devices. The compact design of the MySQL server
makes development in both directions possible without any conflicts in
the source tree.

Currently, we are not targeting real-time support, although MySQL
replication capabilities offer significant functionality.

MySQL supports high-availability database clustering using the
`NDBCLUSTER' storage engine. See *Note mysql-cluster::.

We are implementing XML functionality beginning in MySQL 5.1, which
supports most of the W3C XPath standard. We plan to increase support
for XML as part of future MySQL development. See *Note xml-functions::.


File: manual.info,  Node: standards,  Next: sql-mode,  Prev: compatibility,  Up: compatibility

1.8.1 What Standards MySQL Follows
----------------------------------

Our aim is to support the full ANSI/ISO SQL standard, but without
making concessions to speed and quality of the code.

ODBC levels 0-3.51.


File: manual.info,  Node: sql-mode,  Next: ansi-mode,  Prev: standards,  Up: compatibility

1.8.2 Selecting SQL Modes
-------------------------

The MySQL server can operate in different SQL modes, and can apply
these modes differentially for different clients. This capability
enables each application to tailor the server's operating mode to its
own requirements.

SQL modes control aspects of server operation such as what SQL syntax
MySQL should support and what kind of data validation checks it should
perform. This makes it easier to use MySQL in different environments
and to use MySQL together with other database servers.

You can set the default SQL mode by starting `mysqld' with the
`--sql-mode="MODE_VALUE"' option. You can also change the mode at
runtime by setting the `sql_mode' system variable with a `SET
[SESSION|GLOBAL] sql_mode='MODE_VALUE'' statement.

For more information on setting the SQL mode, see *Note
server-sql-mode::.


File: manual.info,  Node: ansi-mode,  Next: extensions-to-ansi,  Prev: sql-mode,  Up: compatibility

1.8.3 Running MySQL in ANSI Mode
--------------------------------

You can tell `mysqld' to run in ANSI mode with the `--ansi' startup
option. Running the server in ANSI mode is the same as starting it with
the following options:

     --transaction-isolation=SERIALIZABLE --sql-mode=ANSI

You can achieve the same effect at runtime by executing these two
statements:

     SET GLOBAL TRANSACTION ISOLATION LEVEL SERIALIZABLE;
     SET GLOBAL sql_mode = 'ANSI';

You can see that setting the `sql_mode' system variable to `'ANSI''
enables all SQL mode options that are relevant for ANSI mode as follows:

     mysql> SET GLOBAL sql_mode='ANSI';
     mysql> SELECT @@global.sql_mode;
             -> 'REAL_AS_FLOAT,PIPES_AS_CONCAT,ANSI_QUOTES,IGNORE_SPACE,ANSI'

Note that running the server in ANSI mode with `--ansi' is not quite
the same as setting the SQL mode to `'ANSI''. The `--ansi' option
affects the SQL mode and also sets the transaction isolation level.
Setting the SQL mode to `'ANSI'' has no effect on the isolation level.

See *Note server-options::, and *Note sql-mode::.


File: manual.info,  Node: extensions-to-ansi,  Next: differences-from-ansi,  Prev: ansi-mode,  Up: compatibility

1.8.4 MySQL Extensions to Standard SQL
--------------------------------------

MySQL Server supports some extensions that you probably won't find in
other SQL DBMSs. Be warned that if you use them, your code won't be
portable to other SQL servers. In some cases, you can write code that
includes MySQL extensions, but is still portable, by using comments of
the following form:

     /*! MYSQL-SPECIFIC CODE */

In this case, MySQL Server parses and executes the code within the
comment as it would any other SQL statement, but other SQL servers will
ignore the extensions. For example, MySQL Server recognizes the
`STRAIGHT_JOIN' keyword in the following statement, but other servers
will not:

     SELECT /*! STRAIGHT_JOIN */ col1 FROM table1,table2 WHERE ...

If you add a version number after the ``!'' character, the syntax within
the comment is executed only if the MySQL version is greater than or
equal to the specified version number. The `TEMPORARY' keyword in the
following comment is executed only by servers from MySQL 3.23.02 or
higher:

     CREATE /*!32302 TEMPORARY */ TABLE t (a INT);

The following descriptions list MySQL extensions, organized by category.

   * Organization of data on disk

     MySQL Server maps each database to a directory under the MySQL
     data directory, and maps tables within a database to filenames in
     the database directory. This has a few implications:

        * Database and table names are case sensitive in MySQL Server
          on operating systems that have case-sensitive filenames (such
          as most Unix systems). See *Note
          identifier-case-sensitivity::.

        * You can use standard system commands to back up, rename,
          move, delete, and copy tables that are managed by the
          `MyISAM' storage engine. For example, it is possible to
          rename a `MyISAM' table by renaming the `.MYD', `.MYI', and
          `.frm' files to which the table corresponds. (Nevertheless, it
          is preferable to use `RENAME TABLE' or `ALTER TABLE ...
          RENAME' and let the server rename the files.)

     Database and table names cannot contain pathname separator
     characters (``/'', ``\'').

   * General language syntax

        * By default, strings can be enclosed by either ``"'' or ``''',
          not just by ``'''. (If the `ANSI_QUOTES' SQL mode is enabled,
          strings can be enclosed only by ``''' and the server
          interprets strings enclosed by ``"'' as identifiers.)

        * ``\'' is the escape character in strings.

        * In SQL statements, you can access tables from different
          databases with the DB_NAME.TBL_NAME syntax. Some SQL servers
          provide the same functionality but call this `User space'.
          MySQL Server doesn't support tablespaces such as used in
          statements like this: `CREATE TABLE ralph.my_table ... IN
          my_tablespace'.

   * SQL statement syntax

        * The `ANALYZE TABLE', `CHECK TABLE', `OPTIMIZE TABLE', and
          `REPAIR TABLE' statements.

        * The `CREATE DATABASE', `DROP DATABASE', and `ALTER DATABASE'
          statements. See *Note create-database::, *Note
          drop-database::, and *Note alter-database::.

        * The `DO' statement.

        * `EXPLAIN SELECT' to obtain a description of how tables are
          processed by the query optimizer.

        * The `FLUSH' and `RESET' statements.

        * The `SET' statement. See *Note set-option::.

        * The `SHOW' statement. See *Note show::. As of MySQL 5.0, the
          information produced by many of the MySQL-specific `SHOW'
          statements can be obtained in more standard fashion by using
          `SELECT' to query `INFORMATION_SCHEMA'. See *Note
          information-schema::.

        * Use of `LOAD DATA INFILE'. In many cases, this syntax is
          compatible with Oracle's `LOAD DATA INFILE'. See *Note
          load-data::.

        * Use of `RENAME TABLE'. See *Note rename-table::.

        * Use of `REPLACE' instead of `DELETE' plus `INSERT'. See *Note
          replace::.

        * Use of `CHANGE COL_NAME', `DROP COL_NAME', or `DROP INDEX',
          `IGNORE' or `RENAME' in `ALTER TABLE' statements. Use of
          multiple `ADD', `ALTER', `DROP', or `CHANGE' clauses in an
          `ALTER TABLE' statement.  See *Note alter-table::.

        * Use of index names, indexes on a prefix of a column, and use
          of `INDEX' or `KEY' in `CREATE TABLE' statements. See *Note
          create-table::.

        * Use of `TEMPORARY' or `IF NOT EXISTS' with `CREATE TABLE'.

        * Use of `IF EXISTS' with `DROP TABLE' and `DROP DATABASE'.

        * The capability of dropping multiple tables with a single
          `DROP TABLE' statement.

        * The `ORDER BY' and `LIMIT' clauses of the `UPDATE' and
          `DELETE' statements.

        * `INSERT INTO TBL_NAME SET COL_NAME = ...' syntax.

        * The `DELAYED' clause of the `INSERT' and `REPLACE' statements.

        * The `LOW_PRIORITY' clause of the `INSERT', `REPLACE',
          `DELETE', and `UPDATE' statements.

        * Use of `INTO OUTFILE' or `INTO DUMPFILE' in `SELECT'
          statements. See *Note select::.

        * Options such as `STRAIGHT_JOIN' or `SQL_SMALL_RESULT' in
          `SELECT' statements.

        * You don't need to name all selected columns in the `GROUP BY'
          clause. This gives better performance for some very specific,
          but quite normal queries. See *Note
          group-by-functions-and-modifiers::.

        * You can specify `ASC' and `DESC' with `GROUP BY', not just
          with `ORDER BY'.

        * The ability to set variables in a statement with the `:='
          assignment operator:

               mysql> SELECT @a:=SUM(total),@b:=COUNT(*),@a/@b AS avg
                   -> FROM test_table;
               mysql> SELECT @t1:=(@t2:=1)+@t3:=4,@t1,@t2,@t3;

   * Data types

        * The `MEDIUMINT', `SET', and `ENUM' data types, and the
          various `BLOB' and `TEXT' data types.

        * The `AUTO_INCREMENT', `BINARY', `NULL', `UNSIGNED', and
          `ZEROFILL' data type attributes.

   * Functions and operators

        * To make it easier for users who migrate from other SQL
          environments, MySQL Server supports aliases for many
          functions. For example, all string functions support both
          standard SQL syntax and ODBC syntax.

        * MySQL Server understands the `||' and `&&' operators to mean
          logical OR and AND, as in the C programming language. In
          MySQL Server, `||' and `OR' are synonyms, as are `&&' and
          `AND'.  Because of this nice syntax, MySQL Server doesn't
          support the standard SQL `||' operator for string
          concatenation; use `CONCAT()' instead.  Because `CONCAT()'
          takes any number of arguments, it's easy to convert use of the
          `||' operator to MySQL Server.

        * Use of `COUNT(DISTINCT VALUE_LIST)' where VALUE_LIST has more
          than one element.

        * String comparisons are case-insensitive by default, with sort
          ordering determined by the collation of the current character
          set, which is `latin1' (cp1252 West European) by default. If
          you don't like this, you should declare your columns with the
          `BINARY' attribute or use the `BINARY' cast, which causes
          comparisons to be done using the underlying character code
          values rather then a lexical ordering.

        * The `%' operator is a synonym for `MOD()'. That is, `N % M'
          is equivalent to `MOD(N,M)'.  `%' is supported for C
          programmers and for compatibility with PostgreSQL.

        * The `=', `<>', `<=', `<', `>=', `>', `<<', `>>', `<=>', `AND',
          `OR', or `LIKE' operators may be used in expressions in the
          output column list (to the left of the `FROM') in `SELECT'
          statements. For example:

               mysql> SELECT col1=1 AND col2=2 FROM my_table;

        * The `LAST_INSERT_ID()' function returns the most recent
          `AUTO_INCREMENT' value. See *Note information-functions::.

        * `LIKE' is allowed on numeric values.

        * The `REGEXP' and `NOT REGEXP' extended regular expression
          operators.

        * `CONCAT()' or `CHAR()' with one argument or more than two
          arguments. (In MySQL Server, these functions can take a
          variable number of arguments.)

        * The `BIT_COUNT()', `CASE', `ELT()', `FROM_DAYS()', `FORMAT()',
          `IF()', `PASSWORD()', `ENCRYPT()', `MD5()', `ENCODE()',
          `DECODE()', `PERIOD_ADD()', `PERIOD_DIFF()', `TO_DAYS()', and
          `WEEKDAY()' functions.

        * Use of `TRIM()' to trim substrings. Standard SQL supports
          removal of single characters only.

        * The `GROUP BY' functions `STD()', `BIT_OR()', `BIT_AND()',
          `BIT_XOR()', and `GROUP_CONCAT()'. See *Note
          group-by-functions-and-modifiers::.

For a prioritized list indicating when new extensions are added to
MySQL Server, you should consult the online MySQL development roadmap
at `http://dev.mysql.com/doc/mysql/en/roadmap.html'.


File: manual.info,  Node: differences-from-ansi,  Next: constraints,  Prev: extensions-to-ansi,  Up: compatibility

1.8.5 MySQL Differences from Standard SQL
-----------------------------------------

* Menu:

* ansi-diff-select-into-table::  `SELECT INTO TABLE'
* ansi-diff-transactions::       Transactions and Atomic Operations
* ansi-diff-triggers::           Stored Routines and Triggers
* ansi-diff-foreign-keys::       Foreign Keys
* ansi-diff-views::              Views
* ansi-diff-comments::           '`--'' as the Start of a Comment

We try to make MySQL Server follow the ANSI SQL standard and the ODBC
SQL standard, but MySQL Server performs operations differently in some
cases:

   * There are several differences between the MySQL and standard SQL
     privilege systems. For example, in MySQL, privileges for a table
     are not automatically revoked when you delete a table. You must
     explicitly issue a `REVOKE' statement to revoke privileges for a
     table. For more information, see *Note revoke::.

   * The `CAST()' function does not support cast to `REAL' or `BIGINT'.
     See *Note cast-functions::.


File: manual.info,  Node: ansi-diff-select-into-table,  Next: ansi-diff-transactions,  Prev: differences-from-ansi,  Up: differences-from-ansi

1.8.5.1 `SELECT INTO TABLE'
...........................

MySQL Server doesn't support the `SELECT ... INTO TABLE' Sybase SQL
extension. Instead, MySQL Server supports the `INSERT INTO ... SELECT'
standard SQL syntax, which is basically the same thing. See *Note
insert-select::. For example:

     INSERT INTO tbl_temp2 (fld_id)
         SELECT tbl_temp1.fld_order_id
         FROM tbl_temp1 WHERE tbl_temp1.fld_order_id > 100;

Alternatively, you can use `SELECT ... INTO OUTFILE' or `CREATE TABLE
...  SELECT'.

As of MySQL 5.0, you can use `SELECT ...  INTO' with user-defined
variables. The same syntax can also be used inside stored routines
using cursors and local variables. See *Note select-into-statement::.


File: manual.info,  Node: ansi-diff-transactions,  Next: ansi-diff-triggers,  Prev: ansi-diff-select-into-table,  Up: differences-from-ansi

1.8.5.2 Transactions and Atomic Operations
..........................................

MySQL Server (version 3.23-max and all versions 4.0 and above) supports
transactions with the `InnoDB' transactional storage engine. `InnoDB'
provides _full_ `ACID' compliance. See *Note storage-engines::. For
information about `InnoDB' differences from standard SQL with regard to
treatment of transaction errors, see *Note innodb-error-handling::.

The other non-transactional storage engines in MySQL Server (such as
`MyISAM') follow a different paradigm for data integrity called `atomic
operations.' In transactional terms, `MyISAM' tables effectively always
operate in `AUTOCOMMIT=1' mode. Atomic operations often offer
comparable integrity with higher performance.

Because MySQL Server supports both paradigms, you can decide whether
your applications are best served by the speed of atomic operations or
the use of transactional features. This choice can be made on a
per-table basis.

As noted, the tradeoff for transactional versus non-transactional
storage engines lies mostly in performance.  Transactional tables have
significantly higher memory and disk space requirements, and more CPU
overhead. On the other hand, transactional storage engines such as
`InnoDB' also offer many significant features. MySQL Server's modular
design allows the concurrent use of different storage engines to suit
different requirements and deliver optimum performance in all
situations.

MySQL Enterprise

For expert advice on choosing and tuning storage engines, subscribe to
the MySQL Enterprise Monitor. For more information see
`http://www.mysql.com/products/enterprise/advisors.html'.

But how do you use the features of MySQL Server to maintain rigorous
integrity even with the non-transactional `MyISAM' tables, and how do
these features compare with the transactional storage engines?

   * If your applications are written in a way that is dependent on
     being able to call `ROLLBACK' rather than `COMMIT' in critical
     situations, transactions are more convenient. Transactions also
     ensure that unfinished updates or corrupting activities are not
     committed to the database; the server is given the opportunity to
     do an automatic rollback and your database is saved.

     If you use non-transactional tables, MySQL Server in almost all
     cases allows you to resolve potential problems by including simple
     checks before updates and by running simple scripts that check the
     databases for inconsistencies and automatically repair or warn if
     such an inconsistency occurs. Note that just by using the MySQL
     log or even adding one extra log, you can normally fix tables
     perfectly with no data integrity loss.

   * More often than not, critical transactional updates can be
     rewritten to be atomic. Generally speaking, all integrity problems
     that transactions solve can be done with `LOCK TABLES' or atomic
     updates, ensuring that there are no automatic aborts from the
     server, which is a common problem with transactional database
     systems.

   * To be safe with MySQL Server, regardless of whether you use
     transactional tables, you only need to have backups and have
     binary logging turned on. When that is true, you can recover from
     any situation that you could with any other transactional database
     system. It is always good to have backups, regardless of which
     database system you use.

The transactional paradigm has its benefits and its drawbacks.  Many
users and application developers depend on the ease with which they can
code around problems where an abort appears to be necessary, or is
necessary. However, even if you are new to the atomic operations
paradigm, or more familiar with transactions, do consider the speed
benefit that non-transactional tables can offer on the order of three to
five times the speed of the fastest and most optimally tuned
transactional tables.

In situations where integrity is of highest importance, MySQL Server
offers transaction-level reliability and integrity even for
non-transactional tables. If you lock tables with `LOCK TABLES', all
updates stall until integrity checks are made. If you obtain a `READ
LOCAL' lock (as opposed to a write lock) for a table that allows
concurrent inserts at the end of the table, reads are allowed, as are
inserts by other clients. The newly inserted records are not be seen by
the client that has the read lock until it releases the lock. With
`INSERT DELAYED', you can write inserts that go into a local queue
until the locks are released, without having the client wait for the
insert to complete. See *Note concurrent-inserts::, and *Note
insert-delayed::.

`Atomic,' in the sense that we mean it, is nothing magical. It only
means that you can be sure that while each specific update is running,
no other user can interfere with it, and there can never be an
automatic rollback (which can happen with transactional tables if you
are not very careful). MySQL Server also guarantees that there are no
dirty reads.

Following are some techniques for working with non-transactional tables:

   * Loops that need transactions normally can be coded with the help
     of `LOCK TABLES', and you don't need cursors to update records on
     the fly.

   * To avoid using `ROLLBACK', you can employ the following strategy:

       1. Use `LOCK TABLES' to lock all the tables you want to access.

       2. Test the conditions that must be true before performing the
          update.

       3. Update if the conditions are satisfied.

       4. Use `UNLOCK TABLES' to release your locks.

     This is usually a much faster method than using transactions with
     possible rollbacks, although not always.  The only situation this
     solution doesn't handle is when someone kills the threads in the
     middle of an update. In that case, all locks are released but some
     of the updates may not have been executed.

   * You can also use functions to update records in a single
     operation. You can get a very efficient application by using the
     following techniques:

        * Modify columns relative to their current value.

        * Update only those columns that actually have changed.

     For example, when we are updating customer information, we update
     only the customer data that has changed and test only that none of
     the changed data, or data that depends on the changed data, has
     changed compared to the original row. The test for changed data is
     done with the `WHERE' clause in the `UPDATE' statement. If the
     record wasn't updated, we give the client a message: `Some of the
     data you have changed has been changed by another user.' Then we
     show the old row versus the new row in a window so that the user
     can decide which version of the customer record to use.

     This gives us something that is similar to column locking but is
     actually even better because we only update some of the columns,
     using values that are relative to their current values. This means
     that typical `UPDATE' statements look something like these:

          UPDATE tablename SET pay_back=pay_back+125;

          UPDATE customer
            SET
              customer_date='current_date',
              address='new address',
              phone='new phone',
              money_owed_to_us=money_owed_to_us-125
            WHERE
              customer_id=id AND address='old address' AND phone='old phone';

     This is very efficient and works even if another client has
     changed the values in the `pay_back' or `money_owed_to_us' columns.

   * In many cases, users have wanted `LOCK TABLES' or `ROLLBACK' for
     the purpose of managing unique identifiers. This can be handled
     much more efficiently without locking or rolling back by using an
     `AUTO_INCREMENT' column and either the `LAST_INSERT_ID()' SQL
     function or the *Note `mysql_insert_id()': mysql-insert-id. C API
     function. See *Note information-functions::, and *Note
     mysql-insert-id::.

     You can generally code around the need for row-level locking. Some
     situations really do need it, and `InnoDB' tables support row-level
     locking. Otherwise, with `MyISAM' tables, you can use a flag
     column in the table and do something like the following:

          UPDATE TBL_NAME SET row_flag=1 WHERE id=ID;

     MySQL returns `1' for the number of affected rows if the row was
     found and `row_flag' wasn't `1' in the original row. You can think
     of this as though MySQL Server changed the preceding statement to:

          UPDATE TBL_NAME SET row_flag=1 WHERE id=ID AND row_flag <> 1;


File: manual.info,  Node: ansi-diff-triggers,  Next: ansi-diff-foreign-keys,  Prev: ansi-diff-transactions,  Up: differences-from-ansi

1.8.5.3 Stored Routines and Triggers
....................................

Stored procedures and functions are implemented beginning with MySQL
5.0. See *Note stored-procedures::.

Basic trigger functionality is implemented beginning with MySQL 5.0.2,
with further development planned for MySQL 5.1.  See *Note triggers::.


File: manual.info,  Node: ansi-diff-foreign-keys,  Next: ansi-diff-views,  Prev: ansi-diff-triggers,  Up: differences-from-ansi

1.8.5.4 Foreign Keys
....................

In MySQL Server 3.23.44 and up, the `InnoDB' storage engine supports
checking of foreign key constraints, including `CASCADE', `ON DELETE',
and `ON UPDATE'. See *Note innodb-foreign-key-constraints::.

For storage engines other than `InnoDB', MySQL Server parses the
`FOREIGN KEY' syntax in `CREATE TABLE' statements, but does not use or
store it. In the future, the implementation will be extended to store
this information in the table specification file so that it may be
retrieved by `mysqldump' and ODBC. At a later stage, foreign key
constraints will be implemented for `MyISAM' tables as well.

Foreign key enforcement offers several benefits to database developers:

   * Assuming proper design of the relationships, foreign key
     constraints make it more difficult for a programmer to introduce
     an inconsistency into the database.

   * Centralized checking of constraints by the database server makes
     it unnecessary to perform these checks on the application side.
     This eliminates the possibility that different applications may
     not all check the constraints in the same way.

   * Using cascading updates and deletes can simplify the application
     code.

   * Properly designed foreign key rules aid in documenting
     relationships between tables.

Do keep in mind that these benefits come at the cost of additional
overhead for the database server to perform the necessary checks.
Additional checking by the server affects performance, which for some
applications may be sufficiently undesirable as to be avoided if
possible. (Some major commercial applications have coded the foreign
key logic at the application level for this reason.)

MySQL gives database developers the choice of which approach to use. If
you don't need foreign keys and want to avoid the overhead associated
with enforcing referential integrity, you can choose another storage
engine instead, such as `MyISAM'. (For example, the `MyISAM' storage
engine offers very fast performance for applications that perform only
`INSERT' and `SELECT' operations. In this case, the table has no holes
in the middle and the inserts can be performed concurrently with
retrievals.  See *Note concurrent-inserts::.)

If you choose not to take advantage of referential integrity checks,
keep the following considerations in mind:

   * In the absence of server-side foreign key relationship checking,
     the application itself must handle relationship issues. For
     example, it must take care to insert rows into tables in the
     proper order, and to avoid creating orphaned child records. It
     must also be able to recover from errors that occur in the middle
     of multiple-record insert operations.

   * If `ON DELETE' is the only referential integrity capability an
     application needs, you can achieve a similar effect as of MySQL
     Server 4.0 by using multiple-table `DELETE' statements to delete
     rows from many tables with a single statement. See *Note delete::.

   * A workaround for the lack of `ON DELETE' is to add the appropriate
     `DELETE' statements to your application when you delete records
     from a table that has a foreign key. In practice, this is often as
     quick as using foreign keys and is more portable.

Be aware that the use of foreign keys can sometimes lead to problems:

   * Foreign key support addresses many referential integrity issues,
     but it is still necessary to design key relationships carefully to
     avoid circular rules or incorrect combinations of cascading
     deletes.

   * It is not uncommon for a DBA to create a topology of relationships
     that makes it difficult to restore individual tables from a
     backup. (MySQL alleviates this difficulty by allowing you to
     temporarily disable foreign key checks when reloading a table that
     depends on other tables. See *Note
     innodb-foreign-key-constraints::. As of MySQL 4.1.1, `mysqldump'
     generates dump files that take advantage of this capability
     automatically when they are reloaded.)

Note that foreign keys in SQL are used to check and enforce referential
integrity, not to join tables. If you want to get results from multiple
tables from a `SELECT' statement, you do this by performing a join
between them:

     SELECT * FROM t1 INNER JOIN t2 ON t1.id = t2.id;

See *Note join::, and *Note example-foreign-keys::.

The `FOREIGN KEY' syntax without `ON DELETE ...' is often used by ODBC
applications to produce automatic `WHERE' clauses.


File: manual.info,  Node: ansi-diff-views,  Next: ansi-diff-comments,  Prev: ansi-diff-foreign-keys,  Up: differences-from-ansi

1.8.5.5 Views
.............

Views (including updatable views) are implemented beginning with MySQL
Server 5.0.1. See *Note views::.

Views are useful for allowing users to access a set of relations
(tables) as if it were a single table, and limiting their access to
just that. Views can also be used to restrict access to rows (a subset
of a particular table). For access control to columns, you can also use
the sophisticated privilege system in MySQL Server. See *Note
privilege-system::.

In designing an implementation of views, our ambitious goal, as much as
is possible within the confines of SQL, has been full compliance with
`Codd's Rule #6' for relational database systems: `All views that are
theoretically updatable, should in practice also be updatable.'


File: manual.info,  Node: ansi-diff-comments,  Prev: ansi-diff-views,  Up: differences-from-ansi

1.8.5.6 '`--'' as the Start of a Comment
........................................

Standard SQL uses the C syntax `/* this is a comment */' for comments,
and MySQL Server supports this syntax as well. MySQL also support
extensions to this syntax that allow MySQL-specific SQL to be embedded
in the comment, as described in *Note comments::.

Standard SQL uses ``--'' as a start-comment sequence. MySQL Server uses
``#'' as the start comment character. MySQL Server 3.23.3 and up also
supports a variant of the ``--'' comment style.  That is, the ``--''
start-comment sequence must be followed by a space (or by a control
character such as a newline). The space is required to prevent problems
with automatically generated SQL queries that use constructs such as
the following, where we automatically insert the value of the payment
for `payment':

     UPDATE account SET credit=credit-payment

Consider about what happens if `payment' has a negative value such as
`-1':

     UPDATE account SET credit=credit--1

`credit--1' is a legal expression in SQL, but ``--'' is interpreted as
the start of a comment, part of the expression is discarded. The result
is a statement that has a completely different meaning than intended:

     UPDATE account SET credit=credit

The statement produces no change in value at all. This illustrates that
allowing comments to start with ``--'' can have serious consequences.

Using our implementation requires a space following the ``--'' in order
for it to be recognized as a start-comment sequence in MySQL Server
3.23.3 and newer. Therefore, `credit--1' is safe to use.

Another safe feature is that the `mysql' command-line client ignores
lines that start with ``--''.

The following information is relevant only if you are running a MySQL
version earlier than 3.23.3:

If you have an SQL script in a text file that contains ``--'' comments,
you should use the `replace' utility as follows to convert the comments
to use ``#'' characters before executing the script:

     shell> replace " --" " #" < text-file-with-funny-comments.sql \
              | mysql DB_NAME

That is safer than executing the script in the usual way:

     shell> mysql DB_NAME < text-file-with-funny-comments.sql

You can also edit the script file `in place' to change the ``--''
comments to ``#'' comments:

     shell> replace " --" " #" -- text-file-with-funny-comments.sql

Change them back with this command:

     shell> replace " #" " --" -- text-file-with-funny-comments.sql

See *Note replace-utility::.


File: manual.info,  Node: constraints,  Prev: differences-from-ansi,  Up: compatibility

1.8.6 How MySQL Deals with Constraints
--------------------------------------

* Menu:

* constraint-primary-key::       `PRIMARY KEY' and `UNIQUE' Index Constraints
* constraint-invalid-data::      Constraints on Invalid Data
* constraint-enum::              `ENUM' and `SET' Constraints

MySQL allows you to work both with transactional tables that allow
rollback and with non-transactional tables that do not.  Because of
this, constraint handling is a bit different in MySQL than in other
DBMSs. We must handle the case when you have inserted or updated a lot
of rows in a non-transactional table for which changes cannot be rolled
back when an error occurs.

The basic philosophy is that MySQL Server tries to produce an error for
anything that it can detect while parsing a statement to be executed,
and tries to recover from any errors that occur while executing the
statement. We do this in most cases, but not yet for all.

The options MySQL has when an error occurs are to stop the statement in
the middle or to recover as well as possible from the problem and
continue. By default, the server follows the latter course. This means,
for example, that the server may coerce illegal values to the closest
legal values.

Several SQL mode options are available to provide greater control over
handling of bad data values and whether to continue statement execution
or abort when errors occur. Using these options, you can configure
MySQL Server to act in a more traditional fashion that is like other
DBMSs that reject improper input. The SQL mode can be set globally at
server startup to affect all clients. Individual clients can set the
SQL mode at runtime, which enables each client to select the behavior
most appropriate for its requirements. See *Note server-sql-mode::.

MySQL Enterprise

To be alerted when there is no form of server-enforced data integrity,
subscribe to the MySQL Enterprise Monitor. For more information see
`http://www.mysql.com/products/enterprise/advisors.html'.

The following sections describe how MySQL Server handles different
types of constraints.


File: manual.info,  Node: constraint-primary-key,  Next: constraint-invalid-data,  Prev: constraints,  Up: constraints

1.8.6.1 `PRIMARY KEY' and `UNIQUE' Index Constraints
....................................................

Normally, errors occurs for data-change statements (such as `INSERT' or
`UPDATE') that would violate primary-key, unique-key, or foreign-key
constraints. If you are using a transactional storage engine such as
`InnoDB', MySQL automatically rolls back the statement. If you are
using a non-transactional storage engine, MySQL stops processing the
statement at the row for which the error occurred and leaves any
remaining rows unprocessed.

MySQL supports an `IGNORE' keyword for `INSERT', `UPDATE', and so
forth. If you use it, MySQL ignores primary-key or unique-key
violations and continues processing with the next row. See the section
for the statement that you are using (*Note insert::, *Note update::,
and so forth).

You can get information about the number of rows actually inserted or
updated with the *Note `mysql_info()': mysql-info. C API function.  You
can also use the `SHOW WARNINGS' statement. See *Note mysql-info::, and
*Note show-warnings::.

Currently, only `InnoDB' tables support foreign keys. See *Note
innodb-foreign-key-constraints::. We plan to add foreign key support by
other storage engines in a future MySQL release. See *Note roadmap::.


File: manual.info,  Node: constraint-invalid-data,  Next: constraint-enum,  Prev: constraint-primary-key,  Up: constraints

1.8.6.2 Constraints on Invalid Data
...................................

By default, MySQL is forgiving of illegal or improper data values and
coerces them to legal values for data entry.  However, you can change
the server SQL mode to select more traditional treatment of bad values
such that the server rejects them and aborts the statement in which
they occur. See *Note server-sql-mode::.

This section describes the default (forgiving) behavior of MySQL, as
well as the strict SQL mode and how it differs.

If you are not using strict mode, then whenever you insert an
`incorrect' value into a column, such as a `NULL' into a `NOT NULL'
column or a too-large numeric value into a numeric column, MySQL sets
the column to the `best possible value' instead of producing an error:
The following rules describe in more detail how this works:

   * If you try to store an out of range value into a numeric column,
     MySQL Server instead stores zero, the smallest possible value, or
     the largest possible value, whichever is closest to the invalid
     value.

   * For strings, MySQL stores either the empty string or as much of
     the string as can be stored in the column.

   * If you try to store a string that doesn't start with a number into
     a numeric column, MySQL Server stores 0.

   * Invalid values for `ENUM' and `SET' columns are handled as
     described in *Note constraint-enum::.

   * MySQL allows you to store certain incorrect date values into
     `DATE' and `DATETIME' columns (such as `'2000-02-31'' or
     `'2000-02-00''). The idea is that it's not the job of the SQL
     server to validate dates. If MySQL can store a date value and
     retrieve exactly the same value, MySQL stores it as given. If the
     date is totally wrong (outside the server's ability to store it),
     the special `zero' date value `'0000-00-00'' is stored in the
     column instead.

   * If you try to store `NULL' into a column that doesn't take `NULL'
     values, an error occurs for single-row `INSERT' statements. For
     multiple-row `INSERT' statements or for `INSERT INTO ...  SELECT'
     statements, MySQL Server stores the implicit default value for the
     column data type. In general, this is `0' for numeric types, the
     empty string (`''') for string types, and the `zero' value for
     date and time types.  Implicit default values are discussed in
     *Note data-type-defaults::.

   * If an `INSERT' statement specifies no value for a column, MySQL
     inserts its default value if the column definition includes an
     explicit `DEFAULT' clause. If the definition has no such `DEFAULT'
     clause, MySQL inserts the implicit default value for the column
     data type.

The reason for using the preceding rules in non-strict mode is that we
can't check these conditions until the statement has begun executing.
We can't just roll back if we encounter a problem after updating a few
rows, because the storage engine may not support rollback. The option
of terminating the statement is not that good; in this case, the update
would be `half done,' which is probably the worst possible scenario. In
this case, it's better to `do the best you can' and then continue as if
nothing happened.

In MySQL 5.0.2 and up, you can select stricter treatment of input
values by using the `STRICT_TRANS_TABLES' or `STRICT_ALL_TABLES' SQL
modes:

     SET sql_mode = 'STRICT_TRANS_TABLES';
     SET sql_mode = 'STRICT_ALL_TABLES';

`STRICT_TRANS_TABLES' enables strict mode for transactional storage
engines, and also to some extent for non-transactional engines. It
works like this:

   * For transactional storage engines, bad data values occurring
     anywhere in a statement cause the statement to abort and roll back.

   * For non-transactional storage engines, a statement aborts if the
     error occurs in the first row to be inserted or updated. (When the
     error occurs in the first row, the statement can be aborted to
     leave the table unchanged, just as for a transactional table.)
     Errors in rows after the first do not abort the statement, because
     the table has already been changed by the first row. Instead, bad
     data values are adjusted and result in warnings rather than
     errors. In other words, with `STRICT_TRANS_TABLES', a wrong value
     causes MySQL to roll back all updates done so far, if that can be
     done without changing the table. But once the table has been
     changed, further errors result in adjustments and warnings.

For even stricter checking, enable `STRICT_ALL_TABLES'. This is the
same as `STRICT_TRANS_TABLES' except that for non-transactional storage
engines, errors abort the statement even for bad data in rows following
the first row. This means that if an error occurs partway through a
multiple-row insert or update for a non-transactional table, a partial
update results. Earlier rows are inserted or updated, but those from
the point of the error on are not. To avoid this for non-transactional
tables, either use single-row statements or else use
`STRICT_TRANS_TABLES' if conversion warnings rather than errors are
acceptable. To avoid problems in the first place, do not use MySQL to
check column content.  It is safest (and often faster) to let the
application ensure that it passes only legal values to the database.

With either of the strict mode options, you can cause errors to be
treated as warnings by using `INSERT IGNORE' or `UPDATE IGNORE' rather
than `INSERT' or `UPDATE' without `IGNORE'.


File: manual.info,  Node: constraint-enum,  Prev: constraint-invalid-data,  Up: constraints

1.8.6.3 `ENUM' and `SET' Constraints
....................................

`ENUM' and `SET' columns provide an efficient way to define columns
that can contain only a given set of values. See *Note enum::, and
*Note set::. However, before MySQL 5.0.2, `ENUM' and `SET' columns do
not provide true constraints on entry of invalid data:

   * `ENUM' columns always have a default value. If you specify no
     default value, then it is `NULL' for columns that can have `NULL',
     otherwise it is the first enumeration value in the column
     definition.

   * If you insert an incorrect value into an `ENUM' column or if you
     force a value into an `ENUM' column with `IGNORE', it is set to
     the reserved enumeration value of `0', which is displayed as an
     empty string in string context.

   * If you insert an incorrect value into a `SET' column, the
     incorrect value is ignored. For example, if the column can contain
     the values `'a'', `'b'', and `'c'', an attempt to assign
     `'a,x,b,y'' results in a value of `'a,b''.

As of MySQL 5.0.2, you can configure the server to use strict SQL mode.
See *Note server-sql-mode::. With strict mode enabled, the definition
of a `ENUM' or `SET' column does act as a constraint on values entered
into the column. An error occurs for values that do not satisfy these
conditions:

   * An `ENUM' value must be one of those listed in the column
     definition, or the internal numeric equivalent thereof. The value
     cannot be the error value (that is, 0 or the empty string). For a
     column defined as `ENUM('a','b','c')', values such as `''', `'d'',
     or `'ax'' are illegal and are rejected.

   * A `SET' value must be the empty string or a value consisting only
     of the values listed in the column definition separated by commas.
     For a column defined as `SET('a','b','c')', values such as `'d''
     or `'a,b,c,d'' are illegal and are rejected.

Errors for invalid values can be suppressed in strict mode if you use
`INSERT IGNORE' or `UPDATE IGNORE'. In this case, a warning is
generated rather than an error. For `ENUM', the value is inserted as
the error member (`0'). For `SET', the value is inserted as given except
that any invalid substrings are deleted. For example, `'a,x,b,y''
results in a value of `'a,b''.


File: manual.info,  Node: installing,  Next: tutorial,  Prev: introduction,  Up: Top

2 Installing and Upgrading MySQL
********************************

* Menu:

* general-installation-issues::  General Installation Issues
* quick-standard-installation::  Standard MySQL Installation Using a Binary Distribution
* windows-installation::         Installing MySQL on Windows
* linux-rpm::                    Installing MySQL from RPM Packages on Linux
* mac-os-x-installation::        Installing MySQL on Mac OS X
* solaris-installation::         Installing MySQL on Solaris
* netware-installation::         Installing MySQL on NetWare
* installing-binary::            Installing MySQL from `tar.gz' Packages on Other Unix-Like Systems
* installing-source::            MySQL Installation Using a Source Distribution
* post-installation::            Post-Installation Setup and Testing
* upgrade::                      Upgrading MySQL
* downgrading::                  Downgrading MySQL
* operating-system-specific-notes::  Operating System-Specific Notes
* environment-variables::        Environment Variables
* perl-support::                 Perl Installation Notes

This chapter describes how to obtain and install MySQL. A summary of
the procedure follows and later sections provide the details. If you
plan to upgrade an existing version of MySQL to a newer version rather
than install MySQL for the first time, see *Note upgrade::, for
information about upgrade procedures and about issues that you should
consider before upgrading.

If you are interested in migrating to MySQL from another database
system, you may wish to read *Note faqs-migration::, which contains
answers to some common questions concerning migration issues.

  1. *Determine whether MySQL runs and is supported on your platform.*
     Please note that not all platforms are equally suitable for
     running MySQL, and that not all platforms on which MySQL is known
     to run are officially supported by MySQL AB:

        * For MySQL Enterprise Server, the officially supported
          platforms are listed at
          `http://www.mysql.com/support/supportedplatforms.html'.

        * MySQL Community Server runs on the platforms listed at *Note
          which-os::.

  2. *Choose which distribution to install.* Several versions of MySQL
     are available, and most are available in several distribution
     formats. You can choose from pre-packaged distributions containing
     binary (precompiled) programs or source code. When in doubt, use a
     binary distribution. We also provide public access to our current
     source tree for those who want to see our most recent developments
     and help us test new code. To determine which version and type of
     distribution you should use, see *Note which-version::.

  3. *Download the distribution that you want to install.* For
     instructions, see *Note getting-mysql::. To verify the integrity
     of the distribution, use the instructions in *Note
     verifying-package-integrity::.

  4. *Install the distribution.* To install MySQL from a binary
     distribution, use the instructions in *Note
     quick-standard-installation::. To install MySQL from a source
     distribution or from the current development source tree, use the
     instructions in *Note installing-source::.

     If you encounter installation difficulties, see *Note
     operating-system-specific-notes::, for information on solving
     problems for particular platforms.

  5. *Perform any necessary post-installation setup.* After installing
     MySQL, read *Note post-installation::. This section contains
     important information about making sure the MySQL server is
     working properly. It also describes how to secure the initial
     MySQL user accounts, _which have no passwords_ until you assign
     passwords. The section applies whether you install MySQL using a
     binary or source distribution.

  6. If you want to run the MySQL benchmark scripts, Perl support for
     MySQL must be available. See *Note perl-support::.


File: manual.info,  Node: general-installation-issues,  Next: quick-standard-installation,  Prev: installing,  Up: installing

2.1 General Installation Issues
===============================

* Menu:

* which-os::                     Operating Systems Supported by MySQL Community Server
* which-version::                Choosing Which MySQL Distribution to Install
* getting-mysql::                How to Get MySQL
* verifying-package-integrity::  Verifying Package Integrity Using MD5 Checksums or `GnuPG'
* installation-layouts::         Installation Layouts

The MySQL installation procedure depends on whether you will install
MySQL Enterprise Server or MySQL Community Server. The set of
applicable platforms depends on which distribution you will install:

   * For MySQL Enterprise Server, the officially supported platforms
     are listed at
     `http://www.mysql.com/support/supportedplatforms.html'.

   * MySQL Community Server runs on the platforms listed at *Note
     which-os::.

For MySQL Enterprise Server, install the main distribution plus any
service packs or hotfixes that you wish to apply using the Enterprise
Installer. For platforms that do not yet have an Enterprise Installer,
use the Community Server instructions.

For MySQL Community Server, install the main distribution plus any
hotfixes and updates:

   * Download a binary release, or download a source release and build
     MySQL yourself from the source code.

   * Retrieve MySQL from the Bazaar tree and build it from source.  The
     Bazaar tree contains the latest developer code.

The immediately following sections contain the information necessary to
choose, download, and verify your distribution. The instructions in
later sections of the chapter describe how to install the distribution
that you choose. For binary distributions, see the instructions at
*Note quick-standard-installation::. To build MySQL from source, use
the instructions at *Note installing-source::.


File: manual.info,  Node: which-os,  Next: which-version,  Prev: general-installation-issues,  Up: general-installation-issues

2.1.1 Operating Systems Supported by MySQL Community Server
-----------------------------------------------------------

This section lists the operating systems on which MySQL Community
Server is known to run.

*Important*:

MySQL AB does not necessarily provide official support for all the
platforms listed in this section. For information about those platforms
which MySQL AB officially supports, see MySQL Server Supported
Platforms (http://www.mysql.com/support/supportedplatforms.html) on the
MySQL Web site.

We use GNU Autoconf, so it is possible to port MySQL to all modern
systems that have a C++ compiler and a working implementation of POSIX
threads. (Thread support is needed for the server. To compile only the
client code, the only requirement is a C++ compiler.)

MySQL has been reported to compile successfully on the following
combinations of operating system and thread package.

   * AIX 4.x, 5.x with native threads. See *Note ibm-aix::.

   * Amiga.

   * FreeBSD 5.x and up with native threads.

   * HP-UX 11.x with the native threads. See *Note hp-ux-11-x::.

   * Linux, builds on all fairly recent Linux distributions with
     `glibc' 2.3. See *Note linux::.

   * Mac OS X. See *Note mac-os-x::.

   * NetBSD 1.3/1.4 Intel and NetBSD 1.3 Alpha. See *Note netbsd::.

   * Novell NetWare 6.0 and 6.5. See *Note netware-installation::.

   * OpenBSD 2.5 and with native threads. OpenBSD earlier than 2.5 with
     the MIT-pthreads package. See *Note openbsd::.

   * SCO OpenServer 5.0.X with a recent port of the FSU Pthreads
     package. See *Note sco::.

   * SCO Openserver 6.0.x. See *Note sco-openserver::.

   * SCO UnixWare 7.1.x. See *Note sco-unixware::.

   * SGI Irix 6.x with native threads. See *Note sgi-irix::.

   * Solaris 2.5 and above with native threads on SPARC and x86.  See
     *Note solaris::.

   * Tru64 Unix. See *Note alpha-dec-unix::.

   * Windows 2000, Windows XP, Windows Vista, Windows Server 2003, and
     Windows Server 2008. See *Note windows-installation::.

MySQL has also been known to run on other systems in the past.  See
*Note operating-system-specific-notes::. Some porting effort might be
required for current versions of MySQL on these systems.

Not all platforms are equally well-suited for running MySQL. How well a
certain platform is suited for a high-load mission-critical MySQL
server is determined by the following factors:

   * General stability of the thread library. A platform may have an
     excellent reputation otherwise, but MySQL is only as stable as the
     thread library it calls, even if everything else is perfect.

   * The capability of the kernel and the thread library to take
     advantage of symmetric multi-processor (SMP) systems. In other
     words, when a process creates a thread, it should be possible for
     that thread to run on a CPU different from the original process.

   * The capability of the kernel and the thread library to run many
     threads that acquire and release a mutex over a short critical
     region frequently without excessive context switches. If the
     implementation of `pthread_mutex_lock()' is too anxious to yield
     CPU time, this hurts MySQL tremendously. If this issue is not
     taken care of, adding extra CPUs actually makes MySQL slower.

   * General filesystem stability and performance.

   * If your tables are large, performance is affected by the ability
     of the filesystem to deal with large files at all and to deal with
     them efficiently.

   * Our level of expertise here at MySQL AB with the platform.  If we
     know a platform well, we enable platform-specific optimizations
     and fixes at compile time. We can also provide advice on
     configuring your system optimally for MySQL.

   * The amount of testing we have done internally for similar
     configurations.

   * The number of users that have run MySQL successfully on the
     platform in similar configurations. If this number is high, the
     likelihood of encountering platform-specific surprises is much
     smaller.


File: manual.info,  Node: which-version,  Next: getting-mysql,  Prev: which-os,  Up: general-installation-issues

2.1.2 Choosing Which MySQL Distribution to Install
--------------------------------------------------

* Menu:

* choosing-version::             Choosing Which Version of MySQL to Install
* choosing-distribution-format::  Choosing a Distribution Format
* many-versions::                How and When Updates Are Released
* mysql-binaries::               MySQL Binaries Compiled by MySQL AB

When preparing to install MySQL, you should decide which version to
use. MySQL development occurs in several release series, and you can
pick the one that best fits your needs. After deciding which version to
install, you can choose a distribution format.  Releases are available
in binary or source format.


File: manual.info,  Node: choosing-version,  Next: choosing-distribution-format,  Prev: which-version,  Up: which-version

2.1.2.1 Choosing Which Version of MySQL to Install
..................................................

The first decision to make is whether you want to use a production
(stable) release or a development release. In the MySQL development
process, multiple release series co-exist, each at a different stage of
maturity:

   * MySQL 5.1 is the current development release series.

   * MySQL 5.0 is the current stable (production-quality) release
     series. New releases are issued for bugfixes only; no new features
     are being added that could effect stability.

   * MySQL 4.1, 4.0 and 3.23 are the old stable (production-quality)
     release series. MySQL 4.1 is now at the end of the product
     lifecycle. Active development and support for these versions has
     ended. Extended support for MySQL 4.1 and 4.0 is available.
     According to the MySQL Lifecycle Policy (see
     `http://www.mysql.com/company/legal/lifecycle/#policy'), only
     Security and Severity Level 1 issues will still be fixed for MySQL
     4.0 and 4.1.

We do not believe in a complete code freeze because this prevents us
from making bugfixes and other fixes that must be done. By `somewhat
frozen' we mean that we may add small things that should not affect
anything that currently works in a production release. Naturally,
relevant bugfixes from an earlier series propagate to later series.

Normally, if you are beginning to use MySQL for the first time or
trying to port it to some system for which there is no binary
distribution, we recommend going with the production release series.
Currently, this is MySQL 5.0. All MySQL releases, even those from
development series, are checked with the MySQL benchmarks and an
extensive test suite before being issued.

If you are running an older system and want to upgrade, but do not want
to take the chance of having a non-seamless upgrade, you should upgrade
to the latest version in the same release series you are using (where
only the last part of the version number is newer than yours). We have
tried to fix only fatal bugs and make only small, relatively `safe'
changes to that version.

If you want to use new features not present in the production release
series, you can use a version from a development series. Note that
development releases are not as stable as production releases.

If you want to use the very latest sources containing all current
patches and bugfixes, you can use one of our Bazaar repositories. These
are not `releases' as such, but are available as previews of the code
on which future releases are to be based.

The MySQL naming scheme uses release names that consist of three
numbers and a suffix; for example, *mysql-5.0.12-beta*. The numbers
within the release name are interpreted as follows:

   * The first number (*5*) is the major version and describes the file
     format. All MySQL 5 releases have the same file format.

   * The second number (*0*) is the release level. Taken together, the
     major version and release level constitute the release series
     number.

   * The third number (*12*) is the version number within the release
     series. This is incremented for each new release. Usually you want
     the latest version for the series you have chosen.

For each minor update, the last number in the version string is
incremented. When there are major new features or minor
incompatibilities with previous versions, the second number in the
version string is incremented. When the file format changes, the first
number is increased.

Release names also include a suffix to indicates the stability level of
the release. Releases within a series progress through a set of
suffixes to indicate how the stability level improves. The possible
suffixes are:

   * *alpha* indicates that the release is for preview purposes only.
     Known bugs should be documented in the News section (see *Note
     news::). Most alpha releases implement new commands and
     extensions. Active development that may involve major code changes
     can occur in an alpha release.  However, we do conduct testing
     before issuing a release.

   * *beta* indicates that the release is appropriate for use with new
     development.  Within beta releases, the features and compatibility
     should remain consistent. However, beta releases may contain
     numerous and major unaddressed bugs.

     All APIs, externally visible structures, and columns for SQL
     statements will not change during future beta, release candidate,
     or production releases.

   * *rc* indicates a Release Candidate. Release candidates are
     believed to be stable, having passed all of MySQL's internal
     testing, and with all known fatal runtime bugs fixed. However, the
     release has not been in widespread use long enough to know for
     sure that all bugs have been identified. Only minor fixes are
     added. (A release candidate is what formerly was known as a gamma
     release.)

   * If there is no suffix, it indicates that the release is a General
     Availability (GA) or Production release. GA releases are stable,
     having successfully passed through all earlier release stages and
     are believed to be reliable, free of serious bugs, and suitable
     for use in production systems. Only critical bugfixes are applied
     to the release.

MySQL uses a naming scheme that is slightly different from most other
products. In general, it is usually safe to use any version that has
been out for a couple of weeks without being replaced by a new version
within the same release series.

All releases of MySQL are run through our standard tests and benchmarks
to ensure that they are relatively safe to use.  Because the standard
tests are extended over time to check for all previously found bugs,
the test suite keeps getting better.

All releases have been tested at least with these tools:

   * An internal test suite

     The `mysql-test' directory contains an extensive set of test
     cases. We run these tests for every server binary. See *Note
     mysql-test-suite::, for more information about this test suite.

   * The MySQL benchmark suite

     This suite runs a range of common queries. It is also a test to
     determine whether the latest batch of optimizations actually made
     the code faster. See *Note mysql-benchmarks::.

   * The `crash-me' test

     This test tries to determine what features the database supports
     and what its capabilities and limitations are.  See *Note
     mysql-benchmarks::.

We also test the newest MySQL version in our internal production
environment, on at least one machine. We have more than 100GB of data
to work with.


File: manual.info,  Node: choosing-distribution-format,  Next: many-versions,  Prev: choosing-version,  Up: which-version

2.1.2.2 Choosing a Distribution Format
......................................

After choosing which version of MySQL to install, you should decide
whether to use a binary distribution or a source distribution. In most
cases, you should probably use a binary distribution, if one exists for
your platform. Binary distributions are available in native format for
many platforms, such as RPM files for Linux or PKG package installers
for Mac OS X or Solaris. Distributions also are available as Zip
archives or compressed `tar' files.

Reasons to choose a binary distribution include the following:

   * Binary distributions generally are easier to install than source
     distributions.

   * To satisfy different user requirements, we provide several servers
     in binary distributions. `mysqld' is an optimized server that is a
     smaller, faster binary.  `mysqld-debug' is compiled with debugging
     support.

     Each of these servers is compiled from the same source
     distribution, though with different configuration options.  All
     native MySQL clients can connect to servers from either MySQL
     version.

Under some circumstances, you may be better off installing MySQL from a
source distribution:

   * You want to install MySQL at some explicit location. The standard
     binary distributions are ready to run at any installation
     location, but you might require even more flexibility to place
     MySQL components where you want.

   * You want to configure `mysqld' to ensure that features are
     available that might not be included in the standard binary
     distributions. Here is a list of the most common extra options
     that you may want to use to ensure feature availability:

        * `--with-libwrap'

        * `--with-named-z-libs' (this is done for some of the binaries)

        * `--with-debug[=full]'

   * You want to configure `mysqld' without some features that are
     included in the standard binary distributions. For example,
     distributions normally are compiled with support for all character
     sets. If you want a smaller MySQL server, you can recompile it
     with support for only the character sets you need.

   * You have a special compiler (such as `pgcc') or want to use
     compiler options that are better optimized for your processor.
     Binary distributions are compiled with options that should work on
     a variety of processors from the same processor family.

   * You want to use the latest sources from one of the Bazaar
     repositories to have access to all current bugfixes. For example,
     if you have found a bug and reported it to the MySQL development
     team, the bugfix is committed to the source repository and you can
     access it there. The bugfix does not appear in a release until a
     release actually is issued.

   * You want to read (or modify) the C and C++ code that makes up
     MySQL. For this purpose, you should get a source distribution,
     because the source code is always the ultimate manual.

   * Source distributions contain more tests and examples than binary
     distributions.


File: manual.info,  Node: many-versions,  Next: mysql-binaries,  Prev: choosing-distribution-format,  Up: which-version

2.1.2.3 How and When Updates Are Released
.........................................

MySQL is evolving quite rapidly and we want to share new developments
with other MySQL users. We try to produce a new release whenever we
have new and useful features that others also seem to have a need for.

We also try to help users who request features that are easy to
implement. We take note of what our licensed users want, and we
especially take note of what our support customers want and try to help
them in this regard.

No one is _required_ to download a new release. The News section helps
you determine whether the new release has something you really want. See
*Note news::.

We use the following policy when updating MySQL:

   * Enterprise Server releases are meant to appear every 18 months,
     supplemented by quarterly service packs and monthly rapid updates.
     Community Server releases are meant to appear 2-3 times per year.

   * Releases are issued within each series. Enterprise Server releases
     are numbered using even numbers (for example, 5.1.20). Community
     Server releases are numbered using odd numbers (for example,
     5.1.21).

   * Binary distributions for some platforms are made by us for major
     releases. Other people may make binary distributions for other
     systems, but probably less frequently.

   * We make fixes available as soon as we have identified and
     corrected small or non-critical but annoying bugs. The fixes are
     available in source form immediately from our public Bazaar
     repositories, and are included in the next release.

   * If by any chance a security vulnerability or critical bug is found
     in a release, our policy is to fix it in a new release as soon as
     possible. (We would like other companies to do this, too!)


File: manual.info,  Node: mysql-binaries,  Prev: many-versions,  Up: which-version

2.1.2.4 MySQL Binaries Compiled by MySQL AB
...........................................

As a service of MySQL AB, we provide a set of binary distributions of
MySQL that are compiled on systems at our site or on systems where
supporters of MySQL kindly have given us access to their machines.

In addition to the binaries provided in platform-specific package
formats, we offer binary distributions for a number of platforms in the
form of compressed `tar' files (`.tar.gz' files). See *Note
quick-standard-installation::.

The RPM distributions for MySQL 5.1 releases that we make available
through our Web site are generated by MySQL AB.

For Windows distributions, see *Note windows-installation::.

These distributions are generated using the script
`Build-tools/Do-compile', which compiles the source code and creates
the binary `tar.gz' archive using `scripts/make_binary_distribution'.

These binaries are configured and built with the following compilers
and options. This information can also be obtained by looking at the
variables `COMP_ENV_INFO' and `CONFIGURE_LINE' inside the script
`bin/mysqlbug' of every binary `tar' file distribution.

Anyone who has more optimal options for any of the following
`configure' commands can mail them to the MySQL `internals' mailing
list. See *Note mailing-lists::.

If you want to compile a debug version of MySQL, you should add
`--with-debug' or `--with-debug=full' to the following `configure'
commands and remove any `-fomit-frame-pointer' options.

The following binaries are built on MySQL AB development systems:

   * Linux 2.4.xx x86 with `gcc' 2.95.3:

          CFLAGS="-O2 -mcpu=pentiumpro" CXX=gcc CXXFLAGS="-O2 -mcpu=pentiumpro
          -felide-constructors" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --enable-assembler --disable-shared
          --with-client-ldflags=-all-static --with-mysqld-ldflags=-all-static

   * Linux 2.4.x x86 with `icc' (Intel C++ Compiler 8.1 or later
     releases):

          CC=icc CXX=icpc CFLAGS="-O3 -unroll2 -ip -mp -no-gcc -restrict"
          CXXFLAGS="-O3 -unroll2 -ip -mp -no-gcc -restrict" ./configure
          --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data
          --libexecdir=/usr/local/mysql/bin --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile --enable-assembler
          --disable-shared --with-client-ldflags=-all-static
          --with-mysqld-ldflags=-all-static --with-embedded-server --with-innodb

     Note that versions 8.1 and newer of the Intel compiler have
     separate drivers for 'pure' C (`icc') and C++ (`icpc'); if you use
     `icc' version 8.0 or older for building MySQL, you will need to
     set `CXX=icc'.

   * Linux 2.4.xx Intel Itanium 2 with `ecc' (Intel C++ Itanium
     Compiler 7.0):

          CC=ecc CFLAGS="-O2 -tpp2 -ip -nolib_inline" CXX=ecc CXXFLAGS="-O2
          -tpp2 -ip -nolib_inline" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile

   * Linux 2.4.xx Intel Itanium with `ecc' (Intel C++ Itanium Compiler
     7.0):

          CC=ecc CFLAGS=-tpp1 CXX=ecc CXXFLAGS=-tpp1 ./configure
          --prefix=/usr/local/mysql --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile

   * Linux 2.4.xx alpha with `ccc' (Compaq C V6.2-505 / Compaq C++
     V6.3-006):

          CC=ccc CFLAGS="-fast -arch generic" CXX=cxx CXXFLAGS="-fast -arch
          generic -noexceptions -nortti" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --with-mysqld-ldflags=-non_shared
          --with-client-ldflags=-non_shared --disable-shared

   * Linux 2.x.xx ppc with `gcc' 2.95.4:

          CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3
          -fno-omit-frame-pointer -felide-constructors -fno-exceptions
          -fno-rtti" ./configure --prefix=/usr/local/mysql
          --localstatedir=/usr/local/mysql/data --libexecdir=/usr/local/mysql/bin
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --disable-shared --with-embedded-server
          --with-innodb

   * Linux 2.4.xx s390 with `gcc' 2.95.3:

          CFLAGS="-O2" CXX=gcc CXXFLAGS="-O2 -felide-constructors" ./configure
          --prefix=/usr/local/mysql --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile --disable-shared
          --with-client-ldflags=-all-static --with-mysqld-ldflags=-all-static

   * Linux 2.4.xx x86_64 (AMD64) with `gcc' 3.2.1:

          CXX=gcc ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --disable-shared

   * Sun Solaris 8 x86 with `gcc' 3.2.3:

          CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3
          -fno-omit-frame-pointer -felide-constructors -fno-exceptions
          -fno-rtti" ./configure --prefix=/usr/local/mysql
          --localstatedir=/usr/local/mysql/data --libexecdir=/usr/local/mysql/bin
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --disable-shared --with-innodb

   * Sun Solaris 8 SPARC with `gcc' 3.2:

          CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3
          -fno-omit-frame-pointer -felide-constructors -fno-exceptions
          -fno-rtti" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --enable-assembler --with-named-z-libs=no
          --with-named-curses-libs=-lcurses --disable-shared

   * Sun Solaris 8 SPARC 64-bit with `gcc' 3.2:

          CC=gcc CFLAGS="-O3 -m64 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3
          -m64 -fno-omit-frame-pointer -felide-constructors -fno-exceptions
          -fno-rtti" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --with-named-z-libs=no
          --with-named-curses-libs=-lcurses --disable-shared

   * Sun Solaris 9 SPARC with `gcc' 2.95.3:

          CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3
          -fno-omit-frame-pointer -felide-constructors -fno-exceptions
          -fno-rtti" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --enable-assembler --with-named-curses-libs=-lcurses
          --disable-shared

   * Sun Solaris 9 SPARC with `cc-5.0' (Sun Forte 5.0):

          CC=cc-5.0 CXX=CC ASFLAGS="-xarch=v9" CFLAGS="-Xa -xstrconst -mt
          -D_FORTEC_ -xarch=v9" CXXFLAGS="-noex -mt -D_FORTEC_ -xarch=v9"
          ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile --enable-assembler
          --with-named-z-libs=no --enable-thread-safe-client --disable-shared

   * IBM AIX 4.3.2 ppc with `gcc' 3.2.3:

          CFLAGS="-O2 -mcpu=powerpc -Wa,-many " CXX=gcc CXXFLAGS="-O2
          -mcpu=powerpc -Wa,-many -felide-constructors -fno-exceptions
          -fno-rtti" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --with-named-z-libs=no --disable-shared

   * IBM AIX 4.3.3 ppc with `xlC_r' (IBM Visual Age C/C++ 6.0):

          CC=xlc_r CFLAGS="-ma -O2 -qstrict -qoptimize=2 -qmaxmem=8192"
          CXX=xlC_r CXXFLAGS ="-ma -O2 -qstrict -qoptimize=2 -qmaxmem=8192"
          ./configure --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data
          --libexecdir=/usr/local/mysql/bin --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile --with-named-z-libs=no
          --disable-shared --with-innodb

   * IBM AIX 5.1.0 ppc with `gcc' 3.3:

          CFLAGS="-O2 -mcpu=powerpc -Wa,-many" CXX=gcc CXXFLAGS="-O2 -mcpu=powerpc
          -Wa,-many -felide-constructors -fno-exceptions -fno-rtti" ./configure
          --prefix=/usr/local/mysql --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile --with-named-z-libs=no
          --disable-shared

   * IBM AIX 5.2.0 ppc with `xlC_r' (IBM Visual Age C/C++ 6.0):

          CC=xlc_r CFLAGS="-ma -O2 -qstrict -qoptimize=2 -qmaxmem=8192"
          CXX=xlC_r CXXFLAGS="-ma -O2 -qstrict -qoptimize=2 -qmaxmem=8192"
          ./configure --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data
          --libexecdir=/usr/local/mysql/bin --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile --with-named-z-libs=no
          --disable-shared --with-embedded-server --with-innodb

   * HP-UX 10.20 pa-risc1.1 with `gcc' 3.1:

          CFLAGS="-DHPUX -I/opt/dce/include -O3 -fPIC" CXX=gcc CXXFLAGS="-DHPUX
          -I/opt/dce /include -felide-constructors -fno-exceptions -fno-rtti
          -O3 -fPIC" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --with-pthread --with-named-thread-libs=-ldce
          --with-lib-ccflags=-fPIC --disable-shared

   * HP-UX 11.00 pa-risc with `aCC' (HP ANSI C++ B3910B A.03.50):

          CC=cc CXX=aCC CFLAGS=+DAportable CXXFLAGS=+DAportable ./configure
          --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data
          --libexecdir=/usr/local/mysql/bin --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile --disable-shared
          --with-embedded-server --with-innodb

   * HP-UX 11.11 pa-risc2.0 64bit with `aCC' (HP ANSI C++ B3910B
     A.03.33):

          CC=cc CXX=aCC CFLAGS=+DD64 CXXFLAGS=+DD64 ./configure
          --prefix=/usr/local/mysql --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile --disable-shared

   * HP-UX 11.11 pa-risc2.0 32bit with `aCC' (HP ANSI C++ B3910B
     A.03.33):

          CC=cc CXX=aCC CFLAGS="+DAportable" CXXFLAGS="+DAportable" ./configure
          --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data
          --libexecdir=/usr/local/mysql/bin --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile --disable-shared
          --with-innodb

   * HP-UX 11.22 ia64 64bit with `aCC' (HP aC++/ANSI C B3910B A.05.50):

          CC=cc CXX=aCC CFLAGS="+DD64 +DSitanium2" CXXFLAGS="+DD64 +DSitanium2"
          ./configure --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data
          --libexecdir=/usr/local/mysql/bin --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile --disable-shared
          --with-embedded-server --with-innodb

   * Apple Mac OS X 10.2 powerpc with `gcc' 3.1:

          CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3
          -fno-omit-frame-pointer -felide-constructors -fno-exceptions
          -fno-rtti" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --disable-shared

   * FreeBSD 4.7 i386 with `gcc' 2.95.4:

          CFLAGS=-DHAVE_BROKEN_REALPATH ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --enable-assembler --with-named-z-libs=not-used
          --disable-shared

   * FreeBSD 4.7 i386 using LinuxThreads with `gcc' 2.95.4:

          CFLAGS="-DHAVE_BROKEN_REALPATH -D__USE_UNIX98 -D_REENTRANT
          -D_THREAD_SAFE -I/usr/local/include/pthread/linuxthreads"
          CXXFLAGS="-DHAVE_BROKEN_REALPATH -D__USE_UNIX98 -D_REENTRANT
          -D_THREAD_SAFE -I/usr/local/include/pthread/linuxthreads" ./configure
          --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data
          --libexecdir=/usr/local/mysql/bin --enable-thread-safe-client
          --enable-local-infile --enable-assembler
          --with-named-thread-libs="-DHAVE_GLIBC2_STYLE_GETHOSTBYNAME_R
          -D_THREAD_SAFE -I /usr/local/include/pthread/linuxthreads
          -L/usr/local/lib -llthread -llgcc_r" --disable-shared
          --with-embedded-server --with-innodb

   * QNX Neutrino 6.2.1 i386 with `gcc' 2.95.3qnx-nto 20010315:

          CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3
          -fno-omit-frame-pointer -felide-constructors -fno-exceptions
          -fno-rtti" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --disable-shared

The following binaries are built on third-party systems kindly provided
to MySQL AB by other users. These are provided only as a courtesy;
MySQL AB does not have full control over these systems, so we can
provide only limited support for the binaries built on them.

   * SCO Unix 3.2v5.0.7 i386 with `gcc' 2.95.3:

          CFLAGS="-O3 -mpentium" LDFLAGS=-static CXX=gcc CXXFLAGS="-O3 -mpentium
          -felide-constructors" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --with-named-z-libs=no --enable-thread-safe-client
          --disable-shared

   * SCO UnixWare 7.1.4 i386 with `CC' 3.2:

          CC=cc CFLAGS="-O" CXX=CC ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --with-named-z-libs=no --enable-thread-safe-client
          --disable-shared --with-readline

   * SCO OpenServer 6.0.0 i386 with `CC' 3.2:

          CC=cc CFLAGS="-O" CXX=CC ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --with-named-z-libs=no --enable-thread-safe-client
          --disable-shared --with-readline

   * Compaq Tru64 OSF/1 V5.1 732 alpha with `cc/cxx' (Compaq C
     V6.3-029i / DIGITAL C++ V6.1-027):

          CC="cc -pthread" CFLAGS="-O4 -ansi_alias -ansi_args -fast -inline
          speed -speculate all" CXX="cxx -pthread" CXXFLAGS="-O4 -ansi_alias
          -fast -inline speed -speculate all -noexceptions -nortti" ./configure
          --prefix=/usr/local/mysql --with-extra-charsets=complex
          --enable-thread-safe-client --enable-local-infile
          --with-named-thread-libs="-lpthread -lmach -lexc -lc" --disable-shared
          --with-mysqld-ldflags=-all-static

   * SGI Irix 6.5 IP32 with `gcc' 3.0.1:

          CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXXFLAGS="-O3
          -fno-omit-frame-pointer -felide-constructors -fno-exceptions
          -fno-rtti" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --disable-shared

   * FreeBSD/sparc64 5.0 with `gcc' 3.2.1:

          CFLAGS=-DHAVE_BROKEN_REALPATH ./configure --prefix=/usr/local/mysql
          --localstatedir=/usr/local/mysql/data --libexecdir=/usr/local/mysql/bin
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --disable-shared --with-innodb

The following compile options have been used for binary packages that
MySQL AB provided in the past. These binaries no longer are being
updated, but the compile options are listed here for reference purposes.

   * Linux 2.2.xx SPARC with `egcs' 1.1.2:

          CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3
          -fno-omit-frame-pointer -felide-constructors -fno-exceptions
          -fno-rtti" ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex --enable-thread-safe-client
          --enable-local-infile --enable-assembler --disable-shared

   * Linux 2.2.x with x686 with `gcc' 2.95.2:

          CFLAGS="-O3 -mpentiumpro" CXX=gcc CXXFLAGS="-O3 -mpentiumpro
          -felide-constructors -fno-exceptions -fno-rtti" ./configure
          --prefix=/usr/local/mysql --enable-assembler
          --with-mysqld-ldflags=-all-static --disable-shared
          --with-extra-charsets=complex

   * SunOS 4.1.4 2 sun4c with `gcc' 2.7.2.1:

          CC=gcc CXX=gcc CXXFLAGS="-O3 -felide-constructors" ./configure
          --prefix=/usr/local/mysql --disable-shared --with-extra-charsets=complex
          --enable-assembler

   * SunOS 5.5.1 (and above) sun4u with `egcs' 1.0.3a or 2.90.27 or
     `gcc' 2.95.2 and newer:

          CC=gcc CFLAGS="-O3" CXX=gcc CXXFLAGS="-O3 -felide-constructors
          -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql
          --with-low-memory --with-extra-charsets=complex --enable-assembler

   * SunOS 5.6 i86pc with `gcc' 2.8.1:

          CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql
          --with-low-memory --with-extra-charsets=complex

   * BSDI BSD/OS 3.1 i386 with `gcc' 2.7.2.1:

          CC=gcc CXX=gcc CXXFLAGS=-O ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex

   * BSDI BSD/OS 2.1 i386 with `gcc' 2.7.2:

          CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex

   * AIX 4.2 with `gcc' 2.7.2.2:

          CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql
          --with-extra-charsets=complex


File: manual.info,  Node: getting-mysql,  Next: verifying-package-integrity,  Prev: which-version,  Up: general-installation-issues

2.1.3 How to Get MySQL
----------------------

Check our downloads page at `http://dev.mysql.com/downloads/' for
information about the current version of MySQL and for downloading
instructions. For a complete up-to-date list of MySQL download mirror
sites, see `http://dev.mysql.com/downloads/mirrors.html'. You can also
find information there about becoming a MySQL mirror site and how to
report a bad or out-of-date mirror.

Our main mirror is located at `http://mirrors.sunsite.dk/mysql/'.


File: manual.info,  Node: verifying-package-integrity,  Next: installation-layouts,  Prev: getting-mysql,  Up: general-installation-issues

2.1.4 Verifying Package Integrity Using MD5 Checksums or `GnuPG'
----------------------------------------------------------------

* Menu:

* verifying-md5-checksum::       Verifying the MD5 Checksum
* checking-gpg-signature::       Signature Checking Using `GnuPG'
* checking-rpm-signature::       Signature Checking Using `RPM'

After you have downloaded the MySQL package that suits your needs and
before you attempt to install it, you should make sure that it is
intact and has not been tampered with. MySQL AB offers three means of
integrity checking:

   * MD5 checksums

   * Cryptographic signatures using `GnuPG', the GNU Privacy Guard

   * For RPM packages, the built-in RPM integrity verification mechanism

The following sections describe how to use these methods.

If you notice that the MD5 checksum or GPG signatures do not match,
first try to download the respective package one more time, perhaps
from another mirror site. If you repeatedly cannot successfully verify
the integrity of the package, please notify us about such incidents,
including the full package name and the download site you have been
using, at <webmaster@mysql.com> or <build@mysql.com>. Do not report
downloading problems using the bug-reporting system.


File: manual.info,  Node: verifying-md5-checksum,  Next: checking-gpg-signature,  Prev: verifying-package-integrity,  Up: verifying-package-integrity

2.1.4.1 Verifying the MD5 Checksum
..................................

After you have downloaded a MySQL package, you should make sure that
its MD5 checksum matches the one provided on the MySQL download pages.
Each package has an individual checksum that you can verify with the
following command, where PACKAGE_NAME is the name of the package you
downloaded:

     shell> md5sum PACKAGE_NAME

Example:

     shell> md5sum mysql-standard-5.1.28-linux-i686.tar.gz
     aaab65abbec64d5e907dcd41b8699945  mysql-standard-5.1.28-linux-i686.tar.gz

You should verify that the resulting checksum (the string of
hexadecimal digits) matches the one displayed on the download page
immediately below the respective package.

*Note*:

Make sure to verify the checksum of the _archive file_ (for example,
the `.zip' or `.tar.gz' file) and not of the files that are contained
inside of the archive.

Note that not all operating systems support the `md5sum' command. On
some, it is simply called `md5', and others do not ship it at all. On
Linux, it is part of the *GNU Text Utilities* package, which is
available for a wide range of platforms. You can download the source
code from `http://www.gnu.org/software/textutils/' as well.  If you
have OpenSSL installed, you can use the command `openssl md5
PACKAGE_NAME' instead. A Windows implementation of the `md5' command
line utility is available from `http://www.fourmilab.ch/md5/'.
`winMd5Sum' is a graphical MD5 checking tool that can be obtained from
`http://www.nullriver.com/index/products/winmd5sum'.


File: manual.info,  Node: checking-gpg-signature,  Next: checking-rpm-signature,  Prev: verifying-md5-checksum,  Up: verifying-package-integrity

2.1.4.2 Signature Checking Using `GnuPG'
........................................

Another method of verifying the integrity and authenticity of a package
is to use cryptographic signatures. This is more reliable than using
MD5 checksums, but requires more work.

At MySQL AB, we sign MySQL downloadable packages with `GnuPG' (GNU
Privacy Guard).  `GnuPG' is an Open Source alternative to the
well-known Pretty Good Privacy (`PGP') by Phil Zimmermann. See
`http://www.gnupg.org/' for more information about `GnuPG' and how to
obtain and install it on your system. Most Linux distributions ship
with `GnuPG' installed by default. For more information about `GnuPG',
see `http://www.openpgp.org/'.

To verify the signature for a specific package, you first need to
obtain a copy of MySQL AB's public GPG build key, which you can
download from `http://www.keyserver.net/'.  The key that you want to
obtain is named `build@mysql.com'. Alternatively, you can cut and paste
the key directly from the following text:

     Key ID:
     pub  1024D/5072E1F5 2003-02-03
          MySQL Package signing key (www.mysql.com) <build@mysql.com>
     Fingerprint: A4A9 4068 76FC BD3C 4567  70C8 8C71 8D3B 5072 E1F5

     Public Key (ASCII-armored):

     -----BEGIN PGP PUBLIC KEY BLOCK-----
     Version: GnuPG v1.0.6 (GNU/Linux)
     Comment: For info see http://www.gnupg.org

     mQGiBD4+owwRBAC14GIfUfCyEDSIePvEW3SAFUdJBtoQHH/nJKZyQT7h9bPlUWC3
     RODjQReyCITRrdwyrKUGku2FmeVGwn2u2WmDMNABLnpprWPkBdCk96+OmSLN9brZ
     fw2vOUgCmYv2hW0hyDHuvYlQA/BThQoADgj8AW6/0Lo7V1W9/8VuHP0gQwCgvzV3
     BqOxRznNCRCRxAuAuVztHRcEAJooQK1+iSiunZMYD1WufeXfshc57S/+yeJkegNW
     hxwR9pRWVArNYJdDRT+rf2RUe3vpquKNQU/hnEIUHJRQqYHo8gTxvxXNQc7fJYLV
     K2HtkrPbP72vwsEKMYhhr0eKCbtLGfls9krjJ6sBgACyP/Vb7hiPwxh6rDZ7ITnE
     kYpXBACmWpP8NJTkamEnPCia2ZoOHODANwpUkP43I7jsDmgtobZX9qnrAXw+uNDI
     QJEXM6FSbi0LLtZciNlYsafwAPEOMDKpMqAK6IyisNtPvaLd8lH0bPAnWqcyefep
     rv0sxxqUEMcM3o7wwgfN83POkDasDbs3pjwPhxvhz6//62zQJ7Q7TXlTUUwgUGFj
     a2FnZSBzaWduaW5nIGtleSAod3d3Lm15c3FsLmNvbSkgPGJ1aWxkQG15c3FsLmNv
     bT6IXQQTEQIAHQUCPj6jDAUJCWYBgAULBwoDBAMVAwIDFgIBAheAAAoJEIxxjTtQ
     cuH1cY4AnilUwTXn8MatQOiG0a/bPxrvK/gCAJ4oinSNZRYTnblChwFaazt7PF3q
     zIhMBBMRAgAMBQI+PqPRBYMJZgC7AAoJEElQ4SqycpHyJOEAn1mxHijft00bKXvu
     cSo/pECUmppiAJ41M9MRVj5VcdH/KN/KjRtW6tHFPYhMBBMRAgAMBQI+QoIDBYMJ
     YiKJAAoJELb1zU3GuiQ/lpEAoIhpp6BozKI8p6eaabzF5MlJH58pAKCu/ROofK8J
     Eg2aLos+5zEYrB/LsrkCDQQ+PqMdEAgA7+GJfxbMdY4wslPnjH9rF4N2qfWsEN/l
     xaZoJYc3a6M02WCnHl6ahT2/tBK2w1QI4YFteR47gCvtgb6O1JHffOo2HfLmRDRi
     Rjd1DTCHqeyX7CHhcghj/dNRlW2Z0l5QFEcmV9U0Vhp3aFfWC4Ujfs3LU+hkAWzE
     7zaD5cH9J7yv/6xuZVw411x0h4UqsTcWMu0iM1BzELqX1DY7LwoPEb/O9Rkbf4fm
     Le11EzIaCa4PqARXQZc4dhSinMt6K3X4BrRsKTfozBu74F47D8Ilbf5vSYHbuE5p
     /1oIDznkg/p8kW+3FxuWrycciqFTcNz215yyX39LXFnlLzKUb/F5GwADBQf+Lwqq
     a8CGrRfsOAJxim63CHfty5mUc5rUSnTslGYEIOCR1BeQauyPZbPDsDD9MZ1ZaSaf
     anFvwFG6Llx9xkU7tzq+vKLoWkm4u5xf3vn55VjnSd1aQ9eQnUcXiL4cnBGoTbOW
     I39EcyzgslzBdC++MPjcQTcA7p6JUVsP6oAB3FQWg54tuUo0Ec8bsM8b3Ev42Lmu
     QT5NdKHGwHsXTPtl0klk4bQk4OajHsiy1BMahpT27jWjJlMiJc+IWJ0mghkKHt92
     6s/ymfdf5HkdQ1cyvsz5tryVI3Fx78XeSYfQvuuwqp2H139pXGEkg0n6KdUOetdZ
     Whe70YGNPw1yjWJT1IhMBBgRAgAMBQI+PqMdBQkJZgGAAAoJEIxxjTtQcuH17p4A
     n3r1QpVC9yhnW2cSAjq+kr72GX0eAJ4295kl6NxYEuFApmr1+0uUq/SlsQ==
     =YJkx
     -----END PGP PUBLIC KEY BLOCK-----

To import the build key into your personal public GPG keyring, use `gpg
--import'. For example, if you have saved the key in a file named
`mysql_pubkey.asc', the import command looks like this:

     shell> gpg --import mysql_pubkey.asc

After you have downloaded and imported the public build key, download
your desired MySQL package and the corresponding signature, which also
is available from the download page. The signature file has the same
name as the distribution file with an `.asc' extension. For example:

Distribution file  `mysql-standard-5.1.28-linux-i686.tar.gz'
Signature file     `mysql-standard-5.1.28-linux-i686.tar.gz.asc'

Make sure that both files are stored in the same directory and then run
the following command to verify the signature for the distribution file:

     shell> gpg --verify PACKAGE_NAME.asc

Example:

     shell> gpg --verify mysql-standard-5.1.28-linux-i686.tar.gz.asc
     gpg: Signature made Tue 12 Jul 2005 23:35:41 EST using DSA key ID 5072E1F5
     gpg: Good signature from "MySQL Package signing key (www.mysql.com) <build@mysql.com>"

The `Good signature' message indicates that everything is all right.
You can ignore any `insecure memory' warning you might obtain.

See the GPG documentation for more information on how to work with
public keys.


File: manual.info,  Node: checking-rpm-signature,  Prev: checking-gpg-signature,  Up: verifying-package-integrity

2.1.4.3 Signature Checking Using `RPM'
......................................

For RPM packages, there is no separate signature. RPM packages have a
built-in GPG signature and MD5 checksum. You can verify a package by
running the following command:

     shell> rpm --checksig PACKAGE_NAME.rpm

Example:

     shell> rpm --checksig MySQL-server-5.1.28-0.glibc23.i386.rpm
     MySQL-server-5.1.28-0.glibc23.i386.rpm: md5 gpg OK

*Note*:

If you are using RPM 4.1 and it complains about `(GPG) NOT OK (MISSING
KEYS: GPG#5072e1f5)', even though you have imported the MySQL public
build key into your own GPG keyring, you need to import the key into
the RPM keyring first. RPM 4.1 no longer uses your personal GPG keyring
(or GPG itself).  Rather, it maintains its own keyring because it is a
system-wide application and a user's GPG public keyring is a
user-specific file. To import the MySQL public key into the RPM
keyring, first obtain the key as described in *Note
checking-gpg-signature::. Then use `rpm --import' to import the key. For
example, if you have saved the public key in a file named
`mysql_pubkey.asc', import it using this command:

     shell> rpm --import mysql_pubkey.asc

If you need to obtain the MySQL public key, see *Note
checking-gpg-signature::.


File: manual.info,  Node: installation-layouts,  Prev: verifying-package-integrity,  Up: general-installation-issues

2.1.5 Installation Layouts
--------------------------

This section describes the default layout of the directories created by
installing binary or source distributions provided by MySQL AB. A
distribution provided by another vendor might use a layout different
from those shown here.

For MySQL 5.1 on Windows, the default installation directory is
`C:\Program Files\MySQL\MySQL Server 5.1'. (Some Windows users prefer to
install in `C:\mysql', the directory that formerly was used as the
default. However, the layout of the subdirectories remains the same.)
The installation directory has the following subdirectories:

*Directory*               *Contents of Directory*
`bin'                     Client programs and the `mysqld' server
`data'                    Log files, databases
`Docs'                    Manual in CHM format
`examples'                Example programs and scripts
`include'                 Include (header) files
`lib'                     Libraries
`scripts'                 Utility scripts
`share'                   Error message files

Installations created from MySQL AB's Linux RPM distributions result in
files under the following system directories:

*Directory*               *Contents of Directory*
`/usr/bin'                Client programs and scripts
`/usr/sbin'               The `mysqld' server
`/var/lib/mysql'          Log files, databases
`/usr/share/info'         Manual in Info format
`/usr/share/man'          Unix manual pages
`/usr/include/mysql'      Include (header) files
`/usr/lib/mysql'          Libraries
`/usr/share/mysql'        Error message and character set files
`/usr/share/sql-bench'    Benchmarks

On Unix, a `tar' file binary distribution is installed by unpacking it
at the installation location you choose (typically `/usr/local/mysql')
and creates the following directories in that location:

*Directory*               *Contents of Directory*
`bin'                     Client programs and the `mysqld' server
`data'                    Log files, databases
`docs'                    Manual in Info format
`man'                     Unix manual pages
`include'                 Include (header) files
`lib'                     Libraries
`scripts'                 `mysql_install_db'
`share/mysql'             Error message files
`sql-bench'               Benchmarks

A source distribution is installed after you configure and compile it.
By default, the installation step installs files under `/usr/local', in
the following subdirectories:

*Directory*               *Contents of Directory*
`bin'                     Client programs and scripts
`include/mysql'           Include (header) files
`Docs'                    Manual in Info, CHM formats
`man'                     Unix manual pages
`lib/mysql'               Libraries
`libexec'                 The `mysqld' server
`share/mysql'             Error message files
`sql-bench'               Benchmarks and `crash-me' test
`var'                     Databases and log files

Within its installation directory, the layout of a source installation
differs from that of a binary installation in the following ways:

   * The `mysqld' server is installed in the `libexec' directory rather
     than in the `bin' directory.

   * The data directory is `var' rather than `data'.

   * `mysql_install_db' is installed in the `bin' directory rather than
     in the `scripts' directory.

   * The header file and library directories are `include/mysql' and
     `lib/mysql' rather than `include' and `lib'.

You can create your own binary installation from a compiled source
distribution by executing the `scripts/make_binary_distribution' script
from the top directory of the source distribution.


File: manual.info,  Node: quick-standard-installation,  Next: windows-installation,  Prev: general-installation-issues,  Up: installing

2.2 Standard MySQL Installation Using a Binary Distribution
===========================================================

The next several sections cover the installation of MySQL on platforms
where we offer packages using the native packaging format of the
respective platform. (This is also known as performing a `binary
install.') However, binary distributions of MySQL are available for
many other platforms as well. See *Note installing-binary::, for generic
installation instructions for these packages that apply to all
platforms.

See *Note general-installation-issues::, for more information on what
other binary distributions are available and how to obtain them.


File: manual.info,  Node: windows-installation,  Next: linux-rpm,  Prev: quick-standard-installation,  Up: installing

2.3 Installing MySQL on Windows
===============================

* Menu:

* windows-choosing-package::     Choosing An Installation Package
* windows-using-installer::      Installing MySQL with the Automated Installer
* windows-install-wizard::       Using the MySQL Installation Wizard
* windows-config-wizard::        Using the Configuration Wizard
* windows-install-archive::      Installing MySQL from a Noinstall Zip Archive
* windows-extract-archive::      Extracting the Install Archive
* windows-create-option-file::   Creating an Option File
* windows-select-server::        Selecting a MySQL Server Type
* windows-server-first-start::   Starting the Server for the First Time
* windows-start-command-line::   Starting MySQL from the Windows Command Line
* windows-start-service::        Starting MySQL as a Windows Service
* windows-testing::              Testing The MySQL Installation
* windows-troubleshooting::      Troubleshooting a MySQL Installation Under Windows
* windows-upgrading::            Upgrading MySQL on Windows
* windows-vs-unix::              MySQL on Windows Compared to MySQL on Unix

A native Windows distribution of MySQL has been available from MySQL AB
since version 3.21 and represents a sizable percentage of the daily
downloads of MySQL. This section describes the process for installing
MySQL on Windows.

*Note*:

If you are upgrading MySQL from an existing installation older than
MySQL 4.1.5, you must first perform the procedure described in *Note
windows-upgrading::.

To run MySQL on Windows, you need the following:

   * A 32-bit Windows operating system, including Windows 2000, Windows
     XP, Windows Vista, Windows Server 2003, and Windows Server 2008.

     A Windows operating system permits you to run the MySQL server as
     a service. See *Note windows-start-service::.

     Generally, you should install MySQL on Windows using an account
     that has administrator rights. Otherwise, you may encounter
     problems with certain operations such as editing the `PATH'
     environment variable or accessing the `Service Control Manager'.
     Once installed, MySQL does not need to be executed using a user
     with Administrator privileges.

   * TCP/IP protocol support.

   * Enough space on the hard drive to unpack, install, and create the
     databases in accordance with your requirements (generally a
     minimum of 200 megabytes is recommended.)

For a list of limitations within the Windows version of MySQL, see
*Note limits-windows::.

There may also be other requirements, depending on how you plan to use
MySQL:

   * If you plan to connect to the MySQL server via ODBC, you need a
     Connector/ODBC driver. See *Note myodbc-connector::.

   * If you plan to use MySQL server with ADO.NET applications, you
     need the Connector/NET driver. See *Note connector-net::.

   * If you need tables with a size larger than 4GB, install MySQL on
     an NTFS or newer filesystem. Don't forget to use `MAX_ROWS' and
     `AVG_ROW_LENGTH' when you create tables. See *Note create-table::.

MySQL for Windows is available in several distribution formats:

   * Binary distributions are available that contain a setup program
     that installs everything you need so that you can start the server
     immediately. Another binary distribution format contains an
     archive that you simply unpack in the installation location and
     then configure yourself. For details, see *Note
     windows-choosing-package::.

   * The source distribution contains all the code and support files
     for building the executables using the Visual Studio compiler
     system.

Generally speaking, you should use a binary distribution that includes
an installer. It is simpler to use than the others, and you need no
additional tools to get MySQL up and running. The installer for the
Windows version of MySQL, combined with a GUI Configuration Wizard,
automatically installs MySQL, creates an option file, starts the
server, and secures the default user accounts.

*Caution*:

Using virus scanning software such as Norton/Symantec Anti-Virus on
directories containing MySQL data and temporary tables can cause
issues, both in terms of the performance of MySQL and the
virus-scanning software mis-identifying the contents of the files as
containing spam. This is because of the fingerprinting mechanism used
by the virus scanning software, and the way in which MySQL rapidly
updates different files, which may be identified as a potential
security risk.

After installing MySQL Server, it is recommended that you disable virus
scanning on main directory (`datadir') being used to store your MySQL
table data. There is usually a system built into the virus scanning
software to allow certain directories to be specifically ignored during
virus scanning.

In addition, by default, MySQL creates temporary files in the standard
Windows temporary directory. To prevent the temporary files also being
scanned, you should configure a separate temporary directory for MySQL
temporary files and add this to the virus scanning exclusion list. To
do this, add a configuration option for the `tmpdir' parameter to your
`my.ini' configuration file. For more information, see *Note
windows-create-option-file::, and `tmpdir'.

The following section describes how to install MySQL on Windows using a
binary distribution. To use an installation package that does not
include an installer, follow the procedure described in *Note
windows-install-archive::. To install using a source distribution, see
*Note windows-source-build::.

MySQL distributions for Windows can be downloaded from
`http://dev.mysql.com/downloads/'. See *Note getting-mysql::.


File: manual.info,  Node: windows-choosing-package,  Next: windows-using-installer,  Prev: windows-installation,  Up: windows-installation

2.3.1 Choosing An Installation Package
--------------------------------------

For MySQL 5.1, there are three installation packages to choose from
when installing MySQL on Windows:

   * *The Essentials Package*: This package has a filename similar to
     `mysql-essential-5.1.28-win32.msi' and contains the minimum set of
     files needed to install MySQL on Windows, including the
     Configuration Wizard. This package does not include optional
     components such as the embedded server and benchmark suite.

   * *The Complete Package*: This package has a filename similar to
     `mysql-5.1.28-win32.zip' and contains all files needed for a
     complete Windows installation, including the Configuration Wizard.
     This package includes optional components such as the embedded
     server and benchmark suite.

   * *The Noinstall Archive*: This package has a filename similar to
     `mysql-noinstall-5.1.28-win32.zip' and contains all the files
     found in the Complete install package, with the exception of the
     Configuration Wizard.  This package does not include an automated
     installer, and must be manually installed and configured.

The Essentials package is recommended for most users. It is provided as
an `.msi' file for use with the Windows Installer. The Complete and
Noinstall distributions are packaged as Zip archives. To use them, you
must have a tool that can unpack `.zip' files.

Your choice of install package affects the installation process you
must follow. If you choose to install either the Essentials or Complete
install packages, see *Note windows-using-installer::. If you choose to
install MySQL from the Noinstall archive, see *Note
windows-install-archive::.


File: manual.info,  Node: windows-using-installer,  Next: windows-install-wizard,  Prev: windows-choosing-package,  Up: windows-installation

2.3.2 Installing MySQL with the Automated Installer
---------------------------------------------------

New MySQL users can use the MySQL Installation Wizard and MySQL
Configuration Wizard to install MySQL on Windows. These are designed to
install and configure MySQL in such a way that new users can
immediately get started using MySQL.

The MySQL Installation Wizard and MySQL Configuration Wizard are
available in the Essentials and Complete install packages. They are
recommended for most standard MySQL installations.  Exceptions include
users who need to install multiple instances of MySQL on a single
server host and advanced users who want complete control of server
configuration.


File: manual.info,  Node: windows-install-wizard,  Next: windows-config-wizard,  Prev: windows-using-installer,  Up: windows-installation

2.3.3 Using the MySQL Installation Wizard
-----------------------------------------

* Menu:

* mysql-install-wizard-introduction::  Introduction to the Installation Wizard
* mysql-install-wizard-starting::  Downloading and Starting the MySQL Installation Wizard
* mysql-install-wizard-install-type::  Choosing an Install Type
* mysql-install-wizard-custom-install::  The Custom Install Dialog
* mysql-install-wizard-confirmation-dialog::  The Confirmation Dialog
* mysql-install-wizard-changes::  Changes Made by MySQL Installation Wizard
* mysql-install-wizard-upgrading::  Upgrading MySQL with the Installation Wizard


File: manual.info,  Node: mysql-install-wizard-introduction,  Next: mysql-install-wizard-starting,  Prev: windows-install-wizard,  Up: windows-install-wizard

2.3.3.1 Introduction to the Installation Wizard
...............................................

MySQL Installation Wizard is an installer for the MySQL server that
uses the latest installer technologies for Microsoft Windows. The MySQL
Installation Wizard, in combination with the MySQL Configuration
Wizard, allows a user to install and configure a MySQL server that is
ready for use immediately after installation.

The MySQL Installation Wizard is the standard installer for all MySQL
server distributions, version 4.1.5 and higher.  Users of previous
versions of MySQL need to shut down and remove their existing MySQL
installations manually before installing MySQL with the MySQL
Installation Wizard. See *Note mysql-install-wizard-upgrading::, for
more information on upgrading from a previous version.

Microsoft has included an improved version of their Microsoft Windows
Installer (MSI) in the recent versions of Windows. MSI has become the
de-facto standard for application installations on Windows 2000,
Windows XP, and Windows Server 2003. The MySQL Installation Wizard
makes use of this technology to provide a smoother and more flexible
installation process.

The Microsoft Windows Installer Engine was updated with the release of
Windows XP; those using a previous version of Windows can reference
this Microsoft Knowledge Base article
(http://support.microsoft.com/default.aspx?scid=kb;EN-US;292539) for
information on upgrading to the latest version of the Windows Installer
Engine.

In addition, Microsoft has introduced the WiX (Windows Installer XML)
toolkit recently. This is the first highly acknowledged Open Source
project from Microsoft. We have switched to WiX because it is an Open
Source project and it allows us to handle the complete Windows
installation process in a flexible manner using scripts.

Improving the MySQL Installation Wizard depends on the support and
feedback of users like you. If you find that the MySQL Installation
Wizard is lacking some feature important to you, or if you discover a
bug, please report it in our bugs database using the instructions given
in *Note bug-reports::.


File: manual.info,  Node: mysql-install-wizard-starting,  Next: mysql-install-wizard-install-type,  Prev: mysql-install-wizard-introduction,  Up: windows-install-wizard

2.3.3.2 Downloading and Starting the MySQL Installation Wizard
..............................................................

The MySQL installation packages can be downloaded from
`http://dev.mysql.com/downloads/'. If the package you download is
contained within a Zip archive, you need to extract the archive first.

*Note*:

If you are installing on Windows Vista it is best to open a port before
beginning the installation. To do this first ensure that you are logged
in as an administrator, go to the `Control Panel', and double click the
`Windows Firewall' icon. Choose the `Allow a program through Windows
Firewall' option and click the `Add port' button.  Enter `MySQL' into
the `Name' text box and `3306' (or the port of your choice) into the
`Port number' text box. Also ensure that the `TCP' protocol radio
button is selected. If you wish, you can also limit access to the MySQL
server by choosing the `Change scope' button. Confirm your choices by
clicking the `OK' button. If you do not open a port prior to
installation, you cannot configure the MySQL server immediately after
installation. Additionally, when running the MySQL Installation Wizard
on Windows Vista, ensure that you are logged in as a user with
administrative rights.

The process for starting the wizard depends on the contents of the
installation package you download. If there is a `setup.exe' file
present, double-click it to start the installation process. If there is
an `.msi' file present, double-click it to start the installation
process.


File: manual.info,  Node: mysql-install-wizard-install-type,  Next: mysql-install-wizard-custom-install,  Prev: mysql-install-wizard-starting,  Up: windows-install-wizard

2.3.3.3 Choosing an Install Type
................................

There are three installation types available: *Typical*, *Complete*, and
*Custom*.

The *Typical* installation type installs the MySQL server, the `mysql'
command-line client, and the command-line utilities. The command-line
clients and utilities include `mysqldump', `myisamchk', and several
other tools to help you manage the MySQL server.

The *Complete* installation type installs all components included in
the installation package. The full installation package includes
components such as the embedded server library, the benchmark suite,
support scripts, and documentation.

The *Custom* installation type gives you complete control over which
packages you wish to install and the installation path that is used. See
*Note mysql-install-wizard-custom-install::, for more information on
performing a custom install.

If you choose the *Typical* or *Complete* installation types and click
the `Next' button, you advance to the confirmation screen to verify
your choices and begin the installation. If you choose the *Custom*
installation type and click the `Next' button, you advance to the
custom installation dialog, described in *Note
mysql-install-wizard-custom-install::.


File: manual.info,  Node: mysql-install-wizard-custom-install,  Next: mysql-install-wizard-confirmation-dialog,  Prev: mysql-install-wizard-install-type,  Up: windows-install-wizard

2.3.3.4 The Custom Install Dialog
.................................

If you wish to change the installation path or the specific components
that are installed by the MySQL Installation Wizard, choose the *Custom*
installation type.

A tree view on the left side of the custom install dialog lists all
available components. Components that are not installed have a red `X'
icon; components that are installed have a gray icon. To change whether
a component is installed, click on that component's icon and choose a
new option from the drop-down list that appears.

You can change the default installation path by clicking the
`Change...' button to the right of the displayed installation path.

After choosing your installation components and installation path,
click the `Next' button to advance to the confirmation dialog.


File: manual.info,  Node: mysql-install-wizard-confirmation-dialog,  Next: mysql-install-wizard-changes,  Prev: mysql-install-wizard-custom-install,  Up: windows-install-wizard

2.3.3.5 The Confirmation Dialog
...............................

Once you choose an installation type and optionally choose your
installation components, you advance to the confirmation dialog. Your
installation type and installation path are displayed for you to review.

To install MySQL if you are satisfied with your settings, click the
`Install' button. To change your settings, click the `Back' button.  To
exit the MySQL Installation Wizard without installing MySQL, click the
`Cancel' button.

After installation is complete, you have the option of registering with
the MySQL web site. Registration gives you access to post in the MySQL
forums at forums.mysql.com (http://forums.mysql.com), along with the
ability to report bugs at bugs.mysql.com (http://bugs.mysql.com) and to
subscribe to our newsletter. The final screen of the installer provides
a summary of the installation and gives you the option to launch the
MySQL Configuration Wizard, which you can use to create a configuration
file, install the MySQL service, and configure security settings.


File: manual.info,  Node: mysql-install-wizard-changes,  Next: mysql-install-wizard-upgrading,  Prev: mysql-install-wizard-confirmation-dialog,  Up: windows-install-wizard

2.3.3.6 Changes Made by MySQL Installation Wizard
.................................................

Once you click the `Install' button, the MySQL Installation Wizard
begins the installation process and makes certain changes to your
system which are described in the sections that follow.

*Changes to the Registry*

The MySQL Installation Wizard creates one Windows registry key in a
typical install situation, located in
`HKEY_LOCAL_MACHINE\SOFTWARE\MySQL AB'.

The MySQL Installation Wizard creates a key named after the major
version of the server that is being installed, such as `MySQL Server
5.1'. It contains two string values, `Location' and `Version'. The
`Location' string contains the path to the installation directory. In a
default installation it contains `C:\Program Files\MySQL\MySQL Server
5.1\'. The `Version' string contains the release number.  For example,
for an installation of MySQL Server 5.1.28, the key contains a value of
`5.1.28'.

These registry keys are used to help external tools identify the
installed location of the MySQL server, preventing a complete scan of
the hard-disk to determine the installation path of the MySQL server.
The registry keys are not required to run the server, and if you
install MySQL using the `noinstall' Zip archive, the registry keys are
not created.

*Changes to the Start Menu*

The MySQL Installation Wizard creates a new entry in the Windows
`Start' menu under a common MySQL menu heading named after the major
version of MySQL that you have installed. For example, if you install
MySQL 5.1, the MySQL Installation Wizard creates a `MySQL Server 5.1'
section in the `Start' menu.

The following entries are created within the new `Start' menu section:

   * `MySQL Command Line Client': This is a shortcut to the `mysql'
     command-line client and is configured to connect as the `root'
     user. The shortcut prompts for a `root' user password when you
     connect.

   * `MySQL Server Instance Config Wizard': This is a shortcut to the
     MySQL Configuration Wizard. Use this shortcut to configure a newly
     installed server, or to reconfigure an existing server.

   * `MySQL Documentation': This is a link to the MySQL server
     documentation that is stored locally in the MySQL server
     installation directory. This option is not available when the
     MySQL server is installed using the Essentials installation
     package.

*Changes to the File System*

The MySQL Installation Wizard by default installs the MySQL 5.1 server
to `C:\PROGRAM FILES\MySQL\MySQL Server 5.1', where PROGRAM FILES is
the default location for applications in your system, and 5.1 is the
major version of your MySQL server. This is the recommended location
for the MySQL server, replacing the former default location `C:\mysql'.

By default, all MySQL applications are stored in a common directory at
`C:\PROGRAM FILES\MySQL', where PROGRAM FILES is the default location
for applications in your Windows installation. A typical MySQL
installation on a developer machine might look like this:

     C:\Program Files\MySQL\MySQL Server 5.1
     C:\Program Files\MySQL\MySQL Administrator 1.0
     C:\Program Files\MySQL\MySQL Query Browser 1.0

This approach makes it easier to manage and maintain all MySQL
applications installed on a particular system.

In MySQL 5.1.23 and earlier, the default location for the data files
used by MySQL is located within the corresponding MySQL Server
installation directory. For MySQL 5.1.24 and later, the default
location of the data directory is the `AppData' directory configured
for the user that installed the MySQL application.


File: manual.info,  Node: mysql-install-wizard-upgrading,  Prev: mysql-install-wizard-changes,  Up: windows-install-wizard

2.3.3.7 Upgrading MySQL with the Installation Wizard
....................................................

The MySQL Installation Wizard can perform server upgrades automatically
using the upgrade capabilities of MSI. That means you do not need to
remove a previous installation manually before installing a new
release. The installer automatically shuts down and removes the
previous MySQL service before installing the new version.

Automatic upgrades are available only when upgrading between
installations that have the same major and minor version numbers. For
example, you can upgrade automatically from MySQL 4.1.5 to MySQL 4.1.6,
but not from MySQL 5.0 to MySQL 5.1.

See *Note windows-upgrading::.


File: manual.info,  Node: windows-config-wizard,  Next: windows-install-archive,  Prev: windows-install-wizard,  Up: windows-installation

2.3.4 Using the Configuration Wizard
------------------------------------

* Menu:

* mysql-config-wizard-introduction::  Introduction to the Configuration Wizard
* mysql-config-wizard-starting::  Starting the MySQL Configuration Wizard
* mysql-config-wizard-maintenance::  Choosing a Maintenance Option
* mysql-config-wizard-configuration-type::  Choosing a Configuration Type
* mysql-config-wizard-server-type::  The Server Type Dialog
* mysql-config-wizard-database-usage::  The Database Usage Dialog
* mysql-config-wizard-tablespace::  The InnoDB Tablespace Dialog
* mysql-config-wizard-connections::  The Concurrent Connections Dialog
* mysql-config-wizard-networking::  The Networking and Strict Mode Options Dialog
* mysql-config-wizard-character-set::  The Character Set Dialog
* mysql-config-wizard-service::  The Service Options Dialog
* mysql-config-wizard-security::  The Security Options Dialog
* mysql-config-wizard-confirmation::  The Confirmation Dialog
* mysql-config-wizard-file-location::  The Location of the my.ini File
* mysql-config-wizard-editing::  Editing the my.ini File


File: manual.info,  Node: mysql-config-wizard-introduction,  Next: mysql-config-wizard-starting,  Prev: windows-config-wizard,  Up: windows-config-wizard

2.3.4.1 Introduction to the Configuration Wizard
................................................

The MySQL Configuration Wizard helps automate the process of
configuring your server under Windows. The MySQL Configuration Wizard
creates a custom `my.ini' file by asking you a series of questions and
then applying your responses to a template to generate a `my.ini' file
that is tuned to your installation.

The MySQL Configuration Wizard is included with the MySQL 5.1 server,
and is currently available for Windows users only.

The MySQL Configuration Wizard is to a large extent the result of
feedback that MySQL AB has received from many users over a period of
several years. However, if you find that it lacks some feature
important to you, please report it in our bugs database using the
instructions given in *Note bug-reports::.


File: manual.info,  Node: mysql-config-wizard-starting,  Next: mysql-config-wizard-maintenance,  Prev: mysql-config-wizard-introduction,  Up: windows-config-wizard

2.3.4.2 Starting the MySQL Configuration Wizard
...............................................

The MySQL Configuration Wizard is typically launched from the MySQL
Installation Wizard, as the MySQL Installation Wizard exits. You can
also launch the MySQL Configuration Wizard by clicking the `MySQL
Server Instance Config Wizard' entry in the `MySQL' section of the
Windows `Start' menu.

Alternatively, you can navigate to the `bin' directory of your MySQL
installation and launch the `MySQLInstanceConfig.exe' file directly.

*Note*:

If you chose not to open a port prior to installing MySQL on Windows
Vista, you can choose to use the MySQL Server Configuration Wizard
after installation. However, you must open a port in the Windows
Firewall. To do this see the instructions given in *Note
mysql-install-wizard-starting::. Rather than opening a port, you also
have the option of adding MySQL as a program that bypasses the Windows
Firewall. One or the other option is sufficient -- you need not do both.
Additionally, when running the MySQL Server Configuration Wizard on
Windows Vista ensure that you are logged in as a user with
administrative rights.


File: manual.info,  Node: mysql-config-wizard-maintenance,  Next: mysql-config-wizard-configuration-type,  Prev: mysql-config-wizard-starting,  Up: windows-config-wizard

2.3.4.3 Choosing a Maintenance Option
.....................................

If the MySQL Configuration Wizard detects an existing `my.ini' file,
you have the option of either reconfiguring your existing server, or
removing the server instance by deleting the `my.ini' file and stopping
and removing the MySQL service.

To reconfigure an existing server, choose the `Re-configure Instance'
option and click the `Next' button. Your existing `my.ini' file is
renamed to `myTIMESTAMP.ini.bak', where TIMESTAMP is the date and time
at which the existing `my.ini' file was created. To remove the existing
server instance, choose the `Remove Instance' option and click the
`Next' button.

If you choose the `Remove Instance' option, you advance to a
confirmation window. Click the `Execute' button. The MySQL Configuration
Wizard stops and removes the MySQL service, and then deletes the
`my.ini' file. The server installation and its `data' folder are not
removed.

If you choose the `Re-configure Instance' option, you advance to the
`Configuration Type' dialog where you can choose the type of
installation that you wish to configure.


File: manual.info,  Node: mysql-config-wizard-configuration-type,  Next: mysql-config-wizard-server-type,  Prev: mysql-config-wizard-maintenance,  Up: windows-config-wizard

2.3.4.4 Choosing a Configuration Type
.....................................

When you start the MySQL Configuration Wizard for a new MySQL
installation, or choose the `Re-configure Instance' option for an
existing installation, you advance to the `Configuration Type' dialog.

There are two configuration types available: `Detailed Configuration'
and `Standard Configuration'. The `Standard Configuration' option is
intended for new users who want to get started with MySQL quickly
without having to make many decisions about server configuration. The
`Detailed Configuration' option is intended for advanced users who want
more fine-grained control over server configuration.

If you are new to MySQL and need a server configured as a single-user
developer machine, the `Standard Configuration' should suit your needs.
Choosing the `Standard Configuration' option causes the MySQL
Configuration Wizard to set all configuration options automatically
with the exception of `Service Options' and `Security Options'.

The `Standard Configuration' sets options that may be incompatible with
systems where there are existing MySQL installations. If you have an
existing MySQL installation on your system in addition to the
installation you wish to configure, the `Detailed Configuration' option
is recommended.

To complete the `Standard Configuration', please refer to the sections
on `Service Options' and `Security Options' in *Note
mysql-config-wizard-service::, and *Note
mysql-config-wizard-security::, respectively.


File: manual.info,  Node: mysql-config-wizard-server-type,  Next: mysql-config-wizard-database-usage,  Prev: mysql-config-wizard-configuration-type,  Up: windows-config-wizard

2.3.4.5 The Server Type Dialog
..............................

There are three different server types available to choose from. The
server type that you choose affects the decisions that the MySQL
Configuration Wizard makes with regard to memory, disk, and processor
usage.

   * `Developer Machine': Choose this option for a typical desktop
     workstation where MySQL is intended only for personal use. It is
     assumed that many other desktop applications are running. The
     MySQL server is configured to use minimal system resources.

   * `Server Machine': Choose this option for a server machine where
     the MySQL server is running alongside other server applications
     such as FTP, email, and Web servers. The MySQL server is
     configured to use a moderate portion of the system resources.

   * `Dedicated MySQL Server Machine': Choose this option for a server
     machine that is intended to run only the MySQL server. It is
     assumed that no other applications are running. The MySQL server
     is configured to use all available system resources.

*Note*:

By selecting one of the preconfigured configurations, the values and
settings of various options in your `my.cnf' or `my.ini' will be
altered accordingly. The default values and options as described in the
reference manual may therefore be different to the options and values
that were created during the execution of the configuration wizard.


File: manual.info,  Node: mysql-config-wizard-database-usage,  Next: mysql-config-wizard-tablespace,  Prev: mysql-config-wizard-server-type,  Up: windows-config-wizard

2.3.4.6 The Database Usage Dialog
.................................

The `Database Usage' dialog allows you to indicate the storage engines
that you expect to use when creating MySQL tables. The option you
choose determines whether the `InnoDB' storage engine is available and
what percentage of the server resources are available to `InnoDB'.

   * `Multifunctional Database': This option enables both the `InnoDB'
     and `MyISAM' storage engines and divides resources evenly between
     the two. This option is recommended for users who use both storage
     engines on a regular basis.

   * `Transactional Database Only': This option enables both the
     `InnoDB' and `MyISAM' storage engines, but dedicates most server
     resources to the `InnoDB' storage engine. This option is
     recommended for users who use `InnoDB' almost exclusively and make
     only minimal use of `MyISAM'.

   * `Non-Transactional Database Only': This option disables the
     `InnoDB' storage engine completely and dedicates all server
     resources to the `MyISAM' storage engine. This option is
     recommended for users who do not use `InnoDB'.

The Configuration Wizard uses a template to generate the server
configuration file. The `Database Usage' dialog sets one of the
following option strings:

     Multifunctional Database:        MIXED
     Transactional Database Only:     INNODB
     Non-Transactional Database Only: MYISAM

When these options are processed through the default template
(my-template.ini) the result is:

     Multifunctional Database:
     default-storage-engine=InnoDB
     _myisam_pct=50

     Transactional Database Only:
     default-storage-engine=InnoDB
     _myisam_pct=5

     Non-Transactional Database Only:
     default-storage-engine=MyISAM
     _myisam_pct=100
     skip-innodb

The `_myisam_pct' value is used to calculate the percentage of
resources dedicated to `MyISAM'. The remaining resources are allocated
to `InnoDB'.


File: manual.info,  Node: mysql-config-wizard-tablespace,  Next: mysql-config-wizard-connections,  Prev: mysql-config-wizard-database-usage,  Up: windows-config-wizard

2.3.4.7 The InnoDB Tablespace Dialog
....................................

Some users may want to locate the `InnoDB' tablespace files in a
different location than the MySQL server data directory. Placing the
tablespace files in a separate location can be desirable if your system
has a higher capacity or higher performance storage device available,
such as a RAID storage system.

To change the default location for the `InnoDB' tablespace files,
choose a new drive from the drop-down list of drive letters and choose
a new path from the drop-down list of paths. To create a custom path,
click the `...' button.

If you are modifying the configuration of an existing server, you must
click the `Modify' button before you change the path. In this situation
you must move the existing tablespace files to the new location
manually before starting the server.


File: manual.info,  Node: mysql-config-wizard-connections,  Next: mysql-config-wizard-networking,  Prev: mysql-config-wizard-tablespace,  Up: windows-config-wizard

2.3.4.8 The Concurrent Connections Dialog
.........................................

To prevent the server from running out of resources, it is important to
limit the number of concurrent connections to the MySQL server that can
be established. The `Concurrent Connections' dialog allows you to
choose the expected usage of your server, and sets the limit for
concurrent connections accordingly. It is also possible to set the
concurrent connection limit manually.

   * `Decision Support (DSS)/OLAP': Choose this option if your server
     does not require a large number of concurrent connections. The
     maximum number of connections is set at 100, with an average of 20
     concurrent connections assumed.

   * `Online Transaction Processing (OLTP)': Choose this option if your
     server requires a large number of concurrent connections. The
     maximum number of connections is set at 500.

   * `Manual Setting': Choose this option to set the maximum number of
     concurrent connections to the server manually. Choose the number
     of concurrent connections from the drop-down box provided, or
     enter the maximum number of connections into the drop-down box if
     the number you desire is not listed.


File: manual.info,  Node: mysql-config-wizard-networking,  Next: mysql-config-wizard-character-set,  Prev: mysql-config-wizard-connections,  Up: windows-config-wizard

2.3.4.9 The Networking and Strict Mode Options Dialog
.....................................................

Use the `Networking Options' dialog to enable or disable TCP/IP
networking and to configure the port number that is used to connect to
the MySQL server.

TCP/IP networking is enabled by default. To disable TCP/IP networking,
uncheck the box next to the `Enable TCP/IP Networking' option.

Port 3306 is used by default. To change the port used to access MySQL,
choose a new port number from the drop-down box or type a new port
number directly into the drop-down box. If the port number you choose
is in use, you are prompted to confirm your choice of port number.

Set the `Server SQL Mode' to either enable or disable strict mode.
Enabling strict mode (default) makes MySQL behave more like other
database management systems.  _If you run applications that rely on
MySQL's old `forgiving' behavior, make sure to either adapt those
applications or to disable strict mode._ For more information about
strict mode, see *Note server-sql-mode::.


File: manual.info,  Node: mysql-config-wizard-character-set,  Next: mysql-config-wizard-service,  Prev: mysql-config-wizard-networking,  Up: windows-config-wizard

2.3.4.10 The Character Set Dialog
.................................

The MySQL server supports multiple character sets and it is possible to
set a default server character set that is applied to all tables,
columns, and databases unless overridden. Use the `Character Set'
dialog to change the default character set of the MySQL server.

   * `Standard Character Set': Choose this option if you want to use
     `latin1' as the default server character set.  `latin1' is used
     for English and many Western European languages.

   * `Best Support For Multilingualism': Choose this option if you want
     to use `utf8' as the default server character set. This is a
     Unicode character set that can store characters from many
     different languages.

   * `Manual Selected Default Character Set / Collation': Choose this
     option if you want to pick the server's default character set
     manually. Choose the desired character set from the provided
     drop-down list.


File: manual.info,  Node: mysql-config-wizard-service,  Next: mysql-config-wizard-security,  Prev: mysql-config-wizard-character-set,  Up: windows-config-wizard

2.3.4.11 The Service Options Dialog
...................................

On Windows platforms, the MySQL server can be installed as a Windows
service. When installed this way, the MySQL server can be started
automatically during system startup, and even restarted automatically
by Windows in the event of a service failure.

The MySQL Configuration Wizard installs the MySQL server as a service
by default, using the service name `MySQL'. If you do not wish to
install the service, uncheck the box next to the `Install As Windows
Service' option. You can change the service name by picking a new
service name from the drop-down box provided or by entering a new
service name into the drop-down box.

*Note*:

Service names can include any legal character except forward (`/') or
backward (`\') slashes, and must be less than 256 characters long.

*Warning*:

If you are installing multiple versions of MySQL onto the same machine,
you _must_ choose a different service name for each version that you
install. If you do not choose a different service for each installed
version then the service manager information will be inconsitent and
this will cause problems when you try to uninstall a previous version.

If you have already installed multiple versions using the same service
name, you must manually edit the contents of the
`HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services' parameters
within the Windows registry to update the association of the service
name with the correct server version.

Typically, when installing multiple versions you create a service name
based on the version information. For example, you might install MySQL
5.1.x as `mysql51', or specific versions such as MySQL 5.1.25 as
`mysql5125'.

To install the MySQL server as a service but not have it started
automatically at startup, uncheck the box next to the `Launch the MySQL
Server Automatically' option.


File: manual.info,  Node: mysql-config-wizard-security,  Next: mysql-config-wizard-confirmation,  Prev: mysql-config-wizard-service,  Up: windows-config-wizard

2.3.4.12 The Security Options Dialog
....................................

_It is strongly recommended that you set a `root' password for your
MySQL server_, and the MySQL Configuration Wizard requires by default
that you do so. If you do not wish to set a `root' password, uncheck
the box next to the `Modify Security Settings' option.

To set the `root' password, enter the desired password into both the
`New root password' and `Confirm' boxes. If you are reconfiguring an
existing server, you need to enter the existing `root' password into
the `Current root password' box.

To prevent `root' logins from across the network, check the box next to
the `Root may only connect from localhost' option. This increases the
security of your `root' account.

To create an anonymous user account, check the box next to the `Create
An Anonymous Account' option.  Creating an anonymous account can
decrease server security and cause login and permission difficulties.
For this reason, it is not recommended.


File: manual.info,  Node: mysql-config-wizard-confirmation,  Next: mysql-config-wizard-file-location,  Prev: mysql-config-wizard-security,  Up: windows-config-wizard

2.3.4.13 The Confirmation Dialog
................................

The final dialog in the MySQL Configuration Wizard is the `Confirmation
Dialog'. To start the configuration process, click the `Execute'
button. To return to a previous dialog, click the `Back' button. To exit
the MySQL Configuration Wizard without configuring the server, click
the `Cancel' button.

After you click the `Execute' button, the MySQL Configuration Wizard
performs a series of tasks and displays the progress onscreen as the
tasks are performed.

The MySQL Configuration Wizard first determines configuration file
options based on your choices using a template prepared by MySQL AB
developers and engineers. This template is named `my-template.ini' and
is located in your server installation directory.

The MySQL Configuration Wizard then writes these options to a `my.ini'
file. The final location of the `my.ini' file is displayed next to the
`Write configuration file' task.

If you chose to create a service for the MySQL server, the MySQL
Configuration Wizard creates and starts the service. If you are
reconfiguring an existing service, the MySQL Configuration Wizard
restarts the service to apply your configuration changes.

If you chose to set a `root' password, the MySQL Configuration Wizard
connects to the server, sets your new `root' password and applies any
other security settings you may have selected.

After the MySQL Configuration Wizard has completed its tasks, it
displays a summary. Click the `Finish' button to exit the MySQL
Configuration Wizard.


File: manual.info,  Node: mysql-config-wizard-file-location,  Next: mysql-config-wizard-editing,  Prev: mysql-config-wizard-confirmation,  Up: windows-config-wizard

2.3.4.14 The Location of the my.ini File
........................................

The MySQL Configuration Wizard places the `my.ini' file in the
installation directory for the MySQL server. This helps associate
configuration files with particular server instances.

To ensure that the MySQL server knows where to look for the `my.ini'
file, an argument similar to this is passed to the MySQL server as part
of the service installation:

     --defaults-file="C:\PROGRAM FILES\MYSQL\MYSQL SERVER 5.1\my.ini"

Here, C:\PROGRAM FILES\MYSQL\MYSQL SERVER 5.1 is replaced with the
installation path to the MySQL Server. The `--defaults-file' option
instructs the MySQL server to read the specified file for configuration
options when it starts.


File: manual.info,  Node: mysql-config-wizard-editing,  Prev: mysql-config-wizard-file-location,  Up: windows-config-wizard

2.3.4.15 Editing the my.ini File
................................

To modify the `my.ini' file, open it with a text editor and make any
necessary changes. You can also modify the server configuration with the
MySQL Administrator (http://www.mysql.com/products/administrator/)
utility.

MySQL clients and utilities such as the `mysql' and `mysqldump'
command-line clients are not able to locate the `my.ini' file located
in the server installation directory. To configure the client and
utility applications, create a new `my.ini' file in the `C:\WINDOWS'
directory (whichever is applicable to your Windows version).


File: manual.info,  Node: windows-install-archive,  Next: windows-extract-archive,  Prev: windows-config-wizard,  Up: windows-installation

2.3.5 Installing MySQL from a Noinstall Zip Archive
---------------------------------------------------

Users who are installing from the Noinstall package can use the
instructions in this section to manually install MySQL. The process for
installing MySQL from a Zip archive is as follows:

  1. Extract the archive to the desired install directory

  2. Create an option file

  3. Choose a MySQL server type

  4. Start the MySQL server

  5. Secure the default user accounts

This process is described in the sections that follow.


File: manual.info,  Node: windows-extract-archive,  Next: windows-create-option-file,  Prev: windows-install-archive,  Up: windows-installation

2.3.6 Extracting the Install Archive
------------------------------------

To install MySQL manually, do the following:

  1. If you are upgrading from a previous version please refer to *Note
     windows-upgrading::, before beginning the upgrade process.

  2. Make sure that you are logged in as a user with administrator
     privileges.

  3. Choose an installation location. Traditionally, the MySQL server
     is installed in `C:\mysql'. The MySQL Installation Wizard installs
     MySQL under `C:\Program Files\MySQL'. If you do not install MySQL
     at `C:\mysql', you must specify the path to the install directory
     during startup or in an option file. See *Note
     windows-create-option-file::.

  4. Extract the install archive to the chosen installation location
     using your preferred Zip archive tool. Some tools may extract the
     archive to a folder within your chosen installation location. If
     this occurs, you can move the contents of the subfolder into the
     chosen installation location.


File: manual.info,  Node: windows-create-option-file,  Next: windows-select-server,  Prev: windows-extract-archive,  Up: windows-installation

2.3.7 Creating an Option File
-----------------------------

If you need to specify startup options when you run the server, you can
indicate them on the command line or place them in an option file. For
options that are used every time the server starts, you may find it
most convenient to use an option file to specify your MySQL
configuration. This is particularly true under the following
circumstances:

   * The installation or data directory locations are different from
     the default locations (`C:\Program Files\MySQL\MySQL Server 5.1'
     and `C:\Program Files\MySQL\MySQL Server 5.1\data').

   * You need to tune the server settings, such as memory, cache, or
     InnoDB configuration information.

When the MySQL server starts on Windows, it looks for options in two
files: the `my.ini' file in the Windows directory, and the `C:\my.cnf'
file. The Windows directory typically is named something like
`C:\WINDOWS'. You can determine its exact location from the value of
the `WINDIR' environment variable using the following command:

     C:\> echo %WINDIR%

MySQL looks for options first in the `my.ini' file, and then in the
`my.cnf' file. However, to avoid confusion, it's best if you use only
one file. If your PC uses a boot loader where `C:' is not the boot
drive, your only option is to use the `my.ini' file. Whichever option
file you use, it must be a plain text file.

You can also make use of the example option files included with your
MySQL distribution; see *Note option-files-preconfigured::.

An option file can be created and modified with any text editor, such
as Notepad. For example, if MySQL is installed in `E:\mysql' and the
data directory is in `E:\mydata\data', you can create an option file
containing a `[mysqld]' section to specify values for the `basedir' and
`datadir' parameters:

     [mysqld]
     # set basedir to your installation path
     basedir=E:/mysql
     # set datadir to the location of your data directory
     datadir=E:/mydata/data

Note that Windows pathnames are specified in option files using
(forward) slashes rather than backslashes. If you do use backslashes,
you must double them:

     [mysqld]
     # set basedir to your installation path
     basedir=E:\\mysql
     # set datadir to the location of your data directory
     datadir=E:\\mydata\\data

MySQL Enterprise

For expert advice on the start-up options appropriate to your
circumstances, subscribe to the MySQL Enterprise Monitor. For more
information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

In MySQL 5.1.23 and earlier, the MySQL installer places the data
directory directly under the directory where you install MySQL.  On
MySQL 5.1.24 and later, the data directory is located within the
`AppData' directory for the user running MySQL.

If you would like to use a data directory in a different location, you
should copy the entire contents of the `data' directory to the new
location. For example, if you want to use `E:\mydata' as the data
directory instead, you must do two things:

  1. Move the entire `data' directory and all of its contents from the
     default location (for example `C:\Program Files\MySQL\MySQL Server
     5.1\data') to `E:\mydata'.

  2. Use a `--datadir' option to specify the new data directory
     location each time you start the server.


File: manual.info,  Node: windows-select-server,  Next: windows-server-first-start,  Prev: windows-create-option-file,  Up: windows-installation

2.3.8 Selecting a MySQL Server Type
-----------------------------------

The following table shows the available servers for Windows in MySQL
5.1.20 and earlier.

*Binary*       *Description*
`mysqld-nt'    Optimized binary with named-pipe support
`mysqld'       Optimized binary without named-pipe support
`mysqld-debug' Like `mysqld-nt', but compiled with full debugging and
               automatic memory allocation checking

The following table shows the available servers for Windows in MySQL
5.1.21 and later.

*Binary*       *Description*
`mysqld'       Optimized binary with named-pipe support
`mysqld-debug' Like `mysqld', but compiled with full debugging and
               automatic memory allocation checking

All of the preceding binaries are optimized for modern Intel
processors, but should work on any Intel i386-class or higher processor.

Each of the servers in a distribution support the same set of storage
engines. The `SHOW ENGINES' statement displays which engines a given
server supports.

All Windows MySQL 5.1 servers have support for symbolic linking of
database directories.

MySQL supports TCP/IP on all Windows platforms. MySQL servers on
Windows support named pipes as indicated in the following list.
However, the default is to use TCP/IP regardless of platform.  (Named
pipes are slower than TCP/IP in many Windows configurations.)

Use of named pipes is subject to these conditions:

   * Named pipes are enabled only if you start the server with the
     `--enable-named-pipe' option. It is necessary to use this option
     explicitly because some users have experienced problems with
     shutting down the MySQL server when named pipes were used.

   * For MySQL 5.1.20 and earlier, named-pipe connections are allowed
     only by the `mysqld-nt' and `mysqld-debug' servers. For MySQL
     5.1.21 and later, the `mysqld' and `mysqld-debug' servers both
     contain support for named-pipe connections.

*Note*:

Most of the examples in this manual use `mysqld' as the server name. If
you choose to use a different server, such as `mysqld-nt' or
`mysqld-debug', make the appropriate substitutions in the commands that
are shown in the examples.


File: manual.info,  Node: windows-server-first-start,  Next: windows-start-command-line,  Prev: windows-select-server,  Up: windows-installation

2.3.9 Starting the Server for the First Time
--------------------------------------------

This section gives a general overview of starting the MySQL server. The
following sections provide more specific information for starting the
MySQL server from the command line or as a Windows service.

The information here applies primarily if you installed MySQL using the
`Noinstall' version, or if you wish to configure and test MySQL
manually rather than with the GUI tools.

The examples in these sections assume that MySQL is installed under the
default location of `C:\Program Files\MySQL\MySQL Server 5.1'. Adjust
the pathnames shown in the examples if you have MySQL installed in a
different location.

Clients have two options. They can use TCP/IP, or they can use a named
pipe if the server supports named-pipe connections.

MySQL for Windows also supports shared-memory connections if the server
is started with the `--shared-memory' option. Clients can connect
through shared memory by using the `--protocol=MEMORY' option.

For information about which server binary to run, see *Note
windows-select-server::.

Testing is best done from a command prompt in a console window (or `DOS
window'). In this way you can have the server display status messages
in the window where they are easy to see. If something is wrong with
your configuration, these messages make it easier for you to identify
and fix any problems.

To start the server, enter this command:

     C:\> "C:\Program Files\MySQL\MySQL Server 5.1\bin\mysqld" --console

For a server that includes `InnoDB' support, you should see the
messages similar to those following as it starts (the pathnames and
sizes may differ):

     InnoDB: The first specified datafile c:\ibdata\ibdata1 did not exist:
     InnoDB: a new database to be created!
     InnoDB: Setting file c:\ibdata\ibdata1 size to 209715200
     InnoDB: Database physically writes the file full: wait...
     InnoDB: Log file c:\iblogs\ib_logfile0 did not exist: new to be created
     InnoDB: Setting log file c:\iblogs\ib_logfile0 size to 31457280
     InnoDB: Log file c:\iblogs\ib_logfile1 did not exist: new to be created
     InnoDB: Setting log file c:\iblogs\ib_logfile1 size to 31457280
     InnoDB: Log file c:\iblogs\ib_logfile2 did not exist: new to be created
     InnoDB: Setting log file c:\iblogs\ib_logfile2 size to 31457280
     InnoDB: Doublewrite buffer not found: creating new
     InnoDB: Doublewrite buffer created
     InnoDB: creating foreign key constraint system tables
     InnoDB: foreign key constraint system tables created
     011024 10:58:25  InnoDB: Started

When the server finishes its startup sequence, you should see something
like this, which indicates that the server is ready to service client
connections:

     mysqld: ready for connections
     Version: '5.1.28'  socket: ''  port: 3306

The server continues to write to the console any further diagnostic
output it produces. You can open a new console window in which to run
client programs.

If you omit the `--console' option, the server writes diagnostic output
to the error log in the data directory (`C:\Program Files\MySQL\MySQL
Server 5.1\data' by default). The error log is the file with the `.err'
extension.

*Note*:

The accounts that are listed in the MySQL grant tables initially have
no passwords. After starting the server, you should set up passwords
for them using the instructions in *Note post-installation::.


File: manual.info,  Node: windows-start-command-line,  Next: windows-start-service,  Prev: windows-server-first-start,  Up: windows-installation

2.3.10 Starting MySQL from the Windows Command Line
---------------------------------------------------

The MySQL server can be started manually from the command line.  This
can be done on any version of Windows.

To start the `mysqld' server from the command line, you should start a
console window (or `DOS window') and enter this command:

     C:\> "C:\Program Files\MySQL\MySQL Server 5.1\bin\mysqld"

The path to `mysqld' may vary depending on the install location of
MySQL on your system.

You can stop the MySQL server by executing this command:

     C:\> "C:\Program Files\MySQL\MySQL Server 5.1\bin\mysqladmin" -u root shutdown

*Note*:

If the MySQL `root' user account has a password, you need to invoke
`mysqladmin' with the `-p' option and supply the password when prompted.

This command invokes the MySQL administrative utility `mysqladmin' to
connect to the server and tell it to shut down. The command connects as
the MySQL `root' user, which is the default administrative account in
the MySQL grant system. Note that users in the MySQL grant system are
wholly independent from any login users under Windows.

If `mysqld' doesn't start, check the error log to see whether the
server wrote any messages there to indicate the cause of the problem.
The error log is located in the `C:\Program Files\MySQL\MySQL Server
5.1\data' directory. It is the file with a suffix of `.err'. You can
also try to start the server as `mysqld --console'; in this case, you
may get some useful information on the screen that may help solve the
problem.

The last option is to start `mysqld' with the `--standalone' and
`--debug' options. In this case, `mysqld' writes a log file
`C:\mysqld.trace' that should contain the reason why `mysqld' doesn't
start. See MySQL Internals: Porting
(http://forge.mysql.com/wiki/MySQL_Internals_Porting).

Use `mysqld --verbose --help' to display all the options that `mysqld'
understands.


File: manual.info,  Node: windows-start-service,  Next: windows-testing,  Prev: windows-start-command-line,  Up: windows-installation

2.3.11 Starting MySQL as a Windows Service
------------------------------------------

On Windows, the recommended way to run MySQL is to install it as a
Windows service, whereby MySQL starts and stops automatically when
Windows starts and stops. A MySQL server installed as a service can
also be controlled from the command line using `NET' commands, or with
the graphical `Services' utility. Generally, to install MySQL as a
Windows service you should be logged in using an account that has
administrator rights.

The `Services' utility (the Windows `Service Control Manager') can be
found in the Windows Control Panel (under `Administrative Tools' on
Windows 2000, XP, Vista and Server 2003).  To avoid conflicts, it is
advisable to close the `Services' utility while performing server
installation or removal operations from the command line.

Before installing MySQL as a Windows service, you should first stop the
current server if it is running by using the following command:

     C:\> "C:\Program Files\MySQL\MySQL Server 5.1\bin\mysqladmin"
               -u root shutdown

*Note*:

If the MySQL `root' user account has a password, you need to invoke
`mysqladmin' with the `-p' option and supply the password when prompted.

This command invokes the MySQL administrative utility `mysqladmin' to
connect to the server and tell it to shut down. The command connects as
the MySQL `root' user, which is the default administrative account in
the MySQL grant system. Note that users in the MySQL grant system are
wholly independent from any login users under Windows.

Install the server as a service using this command:

     C:\> "C:\Program Files\MySQL\MySQL Server 5.1\bin\mysqld" --install

The service-installation command does not start the server.
Instructions for that are given later in this section.

To make it easier to invoke MySQL programs, you can add the pathname of
the MySQL `bin' directory to your Windows system `PATH' environment
variable:

   * On the Windows desktop, right-click on the `My Computer' icon, and
     select `Properties'

   * Next select the `Advanced' tab from the `System Properties' menu
     that appears, and click the `Environment Variables' button.

   * Under `System Variables', select `Path', and then click the `Edit'
     button. The `Edit System Variable' dialogue should appear.

   * Place your cursor at the end of the text appearing in the space
     marked `Variable Value'. (Use the `End' key to ensure that your
     cursor is positioned at the very end of the text in this space.)
     Then enter the complete pathname of your MySQL `bin' directory
     (for example, `C:\Program Files\MySQL\MySQL Server 5.1\bin'), Note
     that there should be a semicolon separating this path from any
     values present in this field. Dismiss this dialogue, and each
     dialogue in turn, by clicking `OK' until all of the dialogues that
     were opened have been dismissed. You should now be able to invoke
     any MySQL executable program by typing its name at the DOS prompt
     from any directory on the system, without having to supply the
     path. This includes the servers, the `mysql' client, and all MySQL
     command-line utilities such as `mysqladmin' and `mysqldump'.

     You should not add the MySQL `bin' directory to your Windows
     `PATH' if you are running multiple MySQL servers on the same
     machine.

*Warning*:

You must exercise great care when editing your system `PATH' by hand;
accidental deletion or modification of any portion of the existing
`PATH' value can leave you with a malfunctioning or even unusable
system.

The following additional arguments can be used in MySQL 5.1 when
installing the service:

   * You can specify a service name immediately following the
     `--install' option. The default service name is `MySQL'.

   * If a service name is given, it can be followed by a single option.
     By convention, this should be `--defaults-file=FILE_NAME' to
     specify the name of an option file from which the server should
     read options when it starts.

     The use of a single option other than `--defaults-file' is
     possible but discouraged. `--defaults-file' is more flexible
     because it enables you to specify multiple startup options for the
     server by placing them in the named option file.

   * You can also specify a `--local-service' option following the
     service name. This causes the server to run using the
     `LocalService' Windows account that has limited system privileges.
     This account is available only for Windows XP or newer. If both
     `--defaults-file' and `--local-service' are given following the
     service name, they can be in any order.

For a MySQL server that is installed as a Windows service, the
following rules determine the service name and option files that the
server uses:

   * If the service-installation command specifies no service name or
     the default service name (`MySQL') following the `--install'
     option, the server uses the a service name of `MySQL' and reads
     options from the `[mysqld]' group in the standard option files.

   * If the service-installation command specifies a service name other
     than `MySQL' following the `--install' option, the server uses that
     service name. It reads options from the `[mysqld]' group and the
     group that has the same name as the service in the standard option
     files. This allows you to use the `[mysqld]' group for options
     that should be used by all MySQL services, and an option group
     with the service name for use by the server installed with that
     service name.

   * If the service-installation command specifies a `--defaults-file'
     option after the service name, the server reads options only from
     the `[mysqld]' group of the named file and ignores the standard
     option files.

As a more complex example, consider the following command:

     C:\> "C:\Program Files\MySQL\MySQL Server 5.1\bin\mysqld"
               --install MySQL --defaults-file=C:\my-opts.cnf

Here, the default service name (`MySQL') is given after the `--install'
option. If no `--defaults-file' option had been given, this command
would have the effect of causing the server to read the `[mysqld]'
group from the standard option files. However, because the
`--defaults-file' option is present, the server reads options from the
`[mysqld]' option group, and only from the named file.

You can also specify options as Start parameters in the Windows
`Services' utility before you start the MySQL service.

Once a MySQL server has been installed as a service, Windows starts the
service automatically whenever Windows starts. The service also can be
started immediately from the `Services' utility, or by using a `NET
START MySQL' command. The `NET' command is not case sensitive.

When run as a service, `mysqld' has no access to a console window, so
no messages can be seen there. If `mysqld' does not start, check the
error log to see whether the server wrote any messages there to
indicate the cause of the problem. The error log is located in the
MySQL data directory (for example, `C:\Program Files\MySQL\MySQL Server
5.1\data'). It is the file with a suffix of `.err'.

When a MySQL server has been installed as a service, and the service is
running, Windows stops the service automatically when Windows shuts
down. The server also can be stopped manually by using the `Services'
utility, the `NET STOP MySQL' command, or the `mysqladmin shutdown'
command.

You also have the choice of installing the server as a manual service
if you do not wish for the service to be started automatically during
the boot process. To do this, use the `--install-manual' option rather
than the `--install' option:

     C:\> "C:\Program Files\MySQL\MySQL Server 5.1\bin\mysqld" --install-manual

To remove a server that is installed as a service, first stop it if it
is running by executing `NET STOP MySQL'.  Then use the `--remove'
option to remove it:

     C:\> "C:\Program Files\MySQL\MySQL Server 5.1\bin\mysqld" --remove

If `mysqld' is not running as a service, you can start it from the
command line. For instructions, see *Note windows-start-command-line::.

Please see *Note windows-troubleshooting::, if you encounter
difficulties during installation.


File: manual.info,  Node: windows-testing,  Next: windows-troubleshooting,  Prev: windows-start-service,  Up: windows-installation

2.3.12 Testing The MySQL Installation
-------------------------------------

You can test whether the MySQL server is working by executing any of
the following commands:

     C:\> "C:\Program Files\MySQL\MySQL Server 5.1\bin\mysqlshow"
     C:\> "C:\Program Files\MySQL\MySQL Server 5.1\bin\mysqlshow" -u root mysql
     C:\> "C:\Program Files\MySQL\MySQL Server 5.1\bin\mysqladmin" version status proc
     C:\> "C:\Program Files\MySQL\MySQL Server 5.1\bin\mysql" test

If `mysqld' is slow to respond to TCP/IP connections from client
programs, there is probably a problem with your DNS. In this case,
start `mysqld' with the `--skip-name-resolve' option and use only
`localhost' and IP numbers in the `Host' column of the MySQL grant
tables.

You can force a MySQL client to use a named-pipe connection rather than
TCP/IP by specifying the `--pipe' or `--protocol=PIPE' option, or by
specifying `.' (period) as the host name. Use the `--socket' option to
specify the name of the pipe if you do not want to use the default pipe
name.

Note that if you have set a password for the `root' account, deleted
the anonymous account, or created a new user account, then you must use
the appropriate `-u' and `-p' options with the commands shown above in
order to connect with the MySQL Server.  See *Note connecting::.

For more information about `mysqlshow', see *Note mysqlshow::.


File: manual.info,  Node: windows-troubleshooting,  Next: windows-upgrading,  Prev: windows-testing,  Up: windows-installation

2.3.13 Troubleshooting a MySQL Installation Under Windows
---------------------------------------------------------

When installing and running MySQL for the first time, you may encounter
certain errors that prevent the MySQL server from starting. The purpose
of this section is to help you diagnose and correct some of these
errors.

Your first resource when troubleshooting server issues is the error
log. The MySQL server uses the error log to record information relevant
to the error that prevents the server from starting. The error log is
located in the data directory specified in your `my.ini' file. The
default data directory location is `C:\Program Files\MySQL\MySQL Server
5.1\data'. See *Note error-log::.

Another source of information regarding possible errors is the console
messages displayed when the MySQL service is starting.  Use the `NET
START MySQL' command from the command line after installing `mysqld' as
a service to see any error messages regarding the starting of the MySQL
server as a service. See *Note windows-start-service::.

The following examples show other common error messages you may
encounter when installing MySQL and starting the server for the first
time:

   * If the MySQL server cannot find the `mysql' privileges database or
     other critical files, you may see these messages:

          System error 1067 has occurred.
          Fatal error: Can't open privilege tables: Table 'mysql.host' doesn't exist

     These messages often occur when the MySQL base or data directories
     are installed in different locations than the default locations
     (`C:\Program Files\MySQL\MySQL Server 5.1' and `C:\Program
     Files\MySQL\MySQL Server 5.1\data', respectively).

     This situation may occur when MySQL is upgraded and installed to a
     new location, but the configuration file is not updated to reflect
     the new location. In addition, there may be old and new
     configuration files that conflict. Be sure to delete or rename any
     old configuration files when upgrading MySQL.

     If you have installed MySQL to a directory other than `C:\Program
     Files\MySQL\MySQL Server 5.1', you need to ensure that the MySQL
     server is aware of this through the use of a configuration
     (`my.ini') file. The `my.ini' file needs to be located in your
     Windows directory, typically `C:\WINDOWS'. You can determine its
     exact location from the value of the `WINDIR' environment variable
     by issuing the following command from the command prompt:

          C:\> echo %WINDIR%

     An option file can be created and modified with any text editor,
     such as Notepad. For example, if MySQL is installed in `E:\mysql'
     and the data directory is `D:\MySQLdata', you can create the option
     file and set up a `[mysqld]' section to specify values for the
     `basedir' and `datadir' parameters:

          [mysqld]
          # set basedir to your installation path
          basedir=E:/mysql
          # set datadir to the location of your data directory
          datadir=D:/MySQLdata

     Note that Windows pathnames are specified in option files using
     (forward) slashes rather than backslashes. If you do use
     backslashes, you must double them:

          [mysqld]
          # set basedir to your installation path
          basedir=C:\\Program Files\\MySQL\\MySQL Server 5.1
          # set datadir to the location of your data directory
          datadir=D:\\MySQLdata

     If you change the `datadir' value in your MySQL configuration
     file, you must move the contents of the existing MySQL data
     directory before restarting the MySQL server.

     See *Note windows-create-option-file::.

   * If you reinstall or upgrade MySQL without first stopping and
     removing the existing MySQL service and install MySQL using the
     MySQL Configuration Wizard, you may see this error:

          Error: Cannot create Windows service for MySql. Error: 0

     This occurs when the Configuration Wizard tries to install the
     service and finds an existing service with the same name.

     One solution to this problem is to choose a service name other
     than `mysql' when using the configuration wizard. This allows the
     new service to be installed correctly, but leaves the outdated
     service in place. Although this is harmless, it is best to remove
     old services that are no longer in use.

     To permanently remove the old `mysql' service, execute the
     following command as a user with administrative privileges, on the
     command-line:

          C:\> sc delete mysql
          [SC] DeleteService SUCCESS

     If the `sc' utility is not available for your version of Windows,
     download the `delsrv' utility from
     `http://www.microsoft.com/windows2000/techinfo/reskit/tools/existing/delsrv-o.asp'
     and use the `delsrv mysql' syntax.


File: manual.info,  Node: windows-upgrading,  Next: windows-vs-unix,  Prev: windows-troubleshooting,  Up: windows-installation

2.3.14 Upgrading MySQL on Windows
---------------------------------

This section lists some of the steps you should take when upgrading
MySQL on Windows.

  1. Review *Note upgrade::, for additional information on upgrading
     MySQL that is not specific to Windows.

  2. You should always back up your current MySQL installation before
     performing an upgrade. See *Note backup::.

  3. Download the latest Windows distribution of MySQL from
     `http://dev.mysql.com/downloads/'.

  4. Before upgrading MySQL, you must stop the server. If the server is
     installed as a service, stop the service with the following
     command from the command prompt:

          C:\> NET STOP MySQL

     If you are not running the MySQL server as a service, use the
     following command to stop it:

          C:\> "C:\Program Files\MySQL\MySQL Server 5.1\bin\mysqladmin" -u root shutdown

     *Note*:

     If the MySQL `root' user account has a password, you need to
     invoke `mysqladmin' with the `-p' option and supply the password
     when prompted.

  5. When upgrading to MySQL 5.1 from a version previous to 4.1.5, or
     when upgrading from a version of MySQL installed from a Zip
     archive to a version of MySQL installed with the MySQL
     Installation Wizard, you must manually remove the previous
     installation and MySQL service (if the server is installed as a
     service).

     To remove the MySQL service, use the following command:

          C:\> C:\mysql\bin\mysqld --remove

     *If you do not remove the existing service, the MySQL Installation
     Wizard may fail to properly install the new MySQL service.*

  6. When upgrading from MySQL 5.1.23 to MySQL 5.1.24, the change in
     the default location of the data directory from a directory within
     the MySQL installation to the `AppData' folder means that you must
     manually copy the data files from your old installation to the new
     location.

  7. If you are using the MySQL Installation Wizard, start the wizard
     as described in *Note windows-install-wizard::.

  8. If you are installing MySQL from a Zip archive, extract the
     archive. You may either overwrite your existing MySQL installation
     (usually located at `C:\mysql'), or install it into a different
     directory, such as `C:\mysql5'.  Overwriting the existing
     installation is recommended.

  9. If you were running MySQL as a Windows service and you had to
     remove the service earlier in this procedure, reinstall the
     service. (See *Note windows-start-service::.)

 10. Restart the server. For example, use `NET START MySQL' if you run
     MySQL as a service, or invoke `mysqld' directly otherwise.

 11. If you encounter errors, see *Note windows-troubleshooting::.


File: manual.info,  Node: windows-vs-unix,  Prev: windows-upgrading,  Up: windows-installation

2.3.15 MySQL on Windows Compared to MySQL on Unix
-------------------------------------------------

MySQL for Windows has proven itself to be very stable. The Windows
version of MySQL has the same features as the corresponding Unix
version, with the following exceptions:

   * *Limited number of ports*

     Windows systems have about 4,000 ports available for client
     connections, and after a connection on a port closes, it takes two
     to four minutes before the port can be reused. In situations where
     clients connect to and disconnect from the server at a high rate,
     it is possible for all available ports to be used up before closed
     ports become available again. If this happens, the MySQL server
     appears to be unresponsive even though it is running. Note that
     ports may be used by other applications running on the machine as
     well, in which case the number of ports available to MySQL is
     lower.

     For more information about this problem, see
     `http://support.microsoft.com/default.aspx?scid=kb;en-us;196271'.

   * *Concurrent reads*

     MySQL depends on the `pread()' and `pwrite()' system calls to be
     able to mix `INSERT' and `SELECT'.  Currently, we use mutexes to
     emulate `pread()' and `pwrite()'.  We intend to replace the file
     level interface with a virtual interface in the future so that we
     can use the `readfile()'/`writefile()' interface to get more
     speed. The current implementation limits the number of open files
     that MySQL 5.1 can use to 2,048, which means that you cannot run
     as many concurrent threads on Windows as on Unix.

   * *Blocking read*

     MySQL uses a blocking read for each connection. That has the
     following implications if named-pipe connections are enabled:

        * A connection is not disconnected automatically after eight
          hours, as happens with the Unix version of MySQL.

        * If a connection hangs, it is not possible to break it without
          killing MySQL.

        * `mysqladmin kill' does not work on a sleeping connection.

        * `mysqladmin shutdown' cannot abort as long as there are
          sleeping connections.

     We plan to fix this problem in the future.

   * *`ALTER TABLE'*

     While you are executing an `ALTER TABLE' statement, the table is
     locked from being used by other threads. This has to do with the
     fact that on Windows, you can't delete a file that is in use by
     another thread. In the future, we may find some way to work around
     this problem.

   * *`DROP TABLE'*

     `DROP TABLE' on a table that is in use by a `MERGE' table does not
     work on Windows because the `MERGE' handler does the table mapping
     hidden from the upper layer of MySQL. Because Windows does not
     allow dropping files that are open, you first must flush all
     `MERGE' tables (with `FLUSH TABLES') or drop the `MERGE' table
     before dropping the table.

   * *`DATA DIRECTORY' and `INDEX DIRECTORY'*

     The `DATA DIRECTORY' and `INDEX DIRECTORY' options for `CREATE
     TABLE' are ignored on Windows, because Windows doesn't support
     symbolic links. These options also are ignored on systems that
     have a non-functional `realpath()' call.

   * *`DROP DATABASE'*

     You cannot drop a database that is in use by some thread.

   * *Case-insensitive names*

     Filenames are not case sensitive on Windows, so MySQL database and
     table names are also not case sensitive on Windows. The only
     restriction is that database and table names must be specified
     using the same case throughout a given statement. See *Note
     identifier-case-sensitivity::.

   * *The ``\'' pathname separator character*

     Pathname components in Windows are separated by the ``\''
     character, which is also the escape character in MySQL. If you are
     using `LOAD DATA INFILE' or `SELECT ...  INTO OUTFILE', use
     Unix-style filenames with ``/'' characters:

          mysql> LOAD DATA INFILE 'C:/tmp/skr.txt' INTO TABLE skr;
          mysql> SELECT * INTO OUTFILE 'C:/tmp/skr.txt' FROM skr;

     Alternatively, you must double the ``\'' character:

          mysql> LOAD DATA INFILE 'C:\\tmp\\skr.txt' INTO TABLE skr;
          mysql> SELECT * INTO OUTFILE 'C:\\tmp\\skr.txt' FROM skr;

   * *Problems with pipes*

     Pipes do not work reliably from the Windows command-line prompt.
     If the pipe includes the character `^Z' / `CHAR(24)', Windows
     thinks that it has encountered end-of-file and aborts the program.

     This is mainly a problem when you try to apply a binary log as
     follows:

          C:\> mysqlbinlog BINARY_LOG_FILE | mysql --user=root

     If you have a problem applying the log and suspect that it is
     because of a `^Z' / `CHAR(24)' character, you can use the
     following workaround:

          C:\> mysqlbinlog BINARY_LOG_FILE --result-file=/tmp/bin.sql
          C:\> mysql --user=root --execute "source /tmp/bin.sql"

     The latter command also can be used to reliably read in any SQL
     file that may contain binary data.

   * *`Access denied for user' error*

     If MySQL cannot resolve your hostname properly, you may get the
     following error when you attempt to run a MySQL client program to
     connect to a server running on the same machine:

          Access denied for user 'SOME_USER'@'unknown'
          to database 'mysql'

     To fix this problem, you should create a file named
     `\windows\hosts' containing the following information:

          127.0.0.1       localhost

Here are some open issues for anyone who might want to help us improve
MySQL on Windows:

   * Add macros to use the faster thread-safe increment/decrement
     methods provided by Windows.


File: manual.info,  Node: linux-rpm,  Next: mac-os-x-installation,  Prev: windows-installation,  Up: installing

2.4 Installing MySQL from RPM Packages on Linux
===============================================

The recommended way to install MySQL on RPM-based Linux distributions
is by using the RPM packages. The RPMs provided by MySQL AB to the
community should work on all versions of Linux that support RPM
packages and use `glibc' 2.3. To obtain RPM packages, see *Note
getting-mysql::.

For non-RPM Linux distributions, you can install MySQL using a
`.tar.gz' package. See *Note installing-binary::.

MySQL AB does provide some platform-specific RPMs; the difference
between a platform-specific RPM and a generic RPM is that a
platform-specific RPM is built on the targeted platform and is linked
dynamically whereas a generic RPM is linked statically with
LinuxThreads.

*Note*:

RPM distributions of MySQL often are provided by other vendors.  Be
aware that they may differ in features and capabilities from those
built by MySQL AB, and that the instructions in this manual do not
necessarily apply to installing them. The vendor's instructions should
be consulted instead.

If you have problems with an RPM file (for example, if you receive the
error `Sorry, the host 'XXXX' could not be looked up'), see *Note
binary-notes-linux::.

In most cases, you need to install only the `MySQL-server' and
`MySQL-client' packages to get a functional MySQL installation. The
other packages are not required for a standard installation.

For upgrades, if your installation was originally produced by
installing multiple RPM packages, it is best to upgrade all the
packages, not just some. For example, if you previously installed the
server and client RPMs, do not upgrade just the server RPM.

If you get a dependency failure when trying to install MySQL packages
(for example, `error: removing these packages would break dependencies:
libmysqlclient.so.10 is needed by ...'), you should also install the
`MySQL-shared-compat' package, which includes both the shared libraries
for backward compatibility (`libmysqlclient.so.12' for MySQL 4.0 and
`libmysqlclient.so.10' for MySQL 3.23).

Some Linux distributions still ship with MySQL 3.23 and they usually
link applications dynamically to save disk space. If these shared
libraries are in a separate package (for example, `MySQL-shared'), it
is sufficient to simply leave this package installed and just upgrade
the MySQL server and client packages (which are statically linked and
do not depend on the shared libraries). For distributions that include
the shared libraries in the same package as the MySQL server (for
example, Red Hat Linux), you could either install our 3.23
`MySQL-shared' RPM, or use the `MySQL-shared-compat' package instead.
(Do not install both.)

The RPM packages shown in the following list are available. The names
shown here use a suffix of `.glibc23.i386.rpm', but particular packages
can have different suffixes, as described later.

   * `MySQL-server-VERSION.glibc23.i386.rpm'

     The MySQL server. You need this unless you only want to connect to
     a MySQL server running on another machine.

   * `MySQL-client-VERSION.glibc23.i386.rpm'

     The standard MySQL client programs. You probably always want to
     install this package.

   * `MySQL-devel-VERSION.glibc23.i386.rpm'

     The libraries and include files that are needed if you want to
     compile other MySQL clients, such as the Perl modules.

   * `MySQL-debuginfo-VERSION.glibc23.i386.rpm'

     This package contains debugging information.  `debuginfo' RPMs are
     never needed to use MySQL software; this is true both for the
     server and for client programs. However, they contain additional
     information that might be needed by a debugger to analyze a crash.

   * `MySQL-shared-VERSION.glibc23.i386.rpm'

     This package contains the shared libraries (`libmysqlclient.so*')
     that certain languages and applications need to dynamically load
     and use MySQL. It contains single-threaded and thread-safe
     libraries. If you install this package, do not install the
     `MySQL-shared-compat' package.

   * `MySQL-shared-compat-VERSION.glibc23.i386.rpm'

     This package includes the shared libraries for MySQL 3.23, 4.0,
     4.1, and 5.1. It contains single-threaded and thread-safe
     libraries. Install this package instead of `MySQL-shared' if you
     have applications installed that are dynamically linked against
     older versions of MySQL but you want to upgrade to the current
     version without breaking the library dependencies.

   * `MySQL-embedded-VERSION.glibc23.i386.rpm'

     The embedded MySQL server library.

   * `MySQL-ndb-management-VERSION.glibc23.i386.rpm',
     `MySQL-ndb-storage-VERSION.glibc23.i386.rpm',
     `MySQL-ndb-tools-VERSION.glibc23.i386.rpm',
     `MySQL-ndb-extra-VERSION.glibc23.i386.rpm'

     Packages that contain additional files for MySQL Cluster
     installations.

     *Note*:

     The `MySQL-ndb-tools' RPM requires a working installation of perl.
     Prior to MySQL 5.1.18, the `DBI' and `HTML::Template' packages
     were also required. See *Note perl-support::, and *Note
     mysql-cluster-utilities-ndb-size::, for more information.

   * `MySQL-test-VERSION.glibc23.i386.rpm'

     This package includes the MySQL test suite.

   * `MySQL-VERSION.src.rpm'

     This contains the source code for all of the previous packages. It
     can also be used to rebuild the RPMs on other architectures (for
     example, Alpha or SPARC).

The suffix of RPM package names (following the VERSION value) has the
following syntax:

     .PLATFORM.CPU.rpm

The PLATFORM and CPU values indicate the type of system for which the
package is built.  PLATFORM indicates the platform and CPU indicates
the processor type or family.

All packages are dynamically linked against `glibc' 2.3. The PLATFORM
value indicates whether the package is platform independent or intended
for a specific platform:

`glibc23'          Platform independent, should run on any Linux
                   distribution that supports `glibc' 2.3
`rhel3', `rhel4'   Red Hat Enterprise Linux 3 or 4
`sles9', `sles10'  SuSE Linux Enterprise Server 9 or 10

In MySQL 5.1, only `glibc23' packages are available currently.

The CPU value indicates the processor type or family for which the
package is built:

`i386'             x86 processor, 386 and up
`i586'             x86 processor, Pentium and up
`x86_64'           64-bit x86 processor
`ia64'             Itanium (IA-64) processor

To see all files in an RPM package (for example, a `MySQL-server' RPM),
run a commnd like this:

     shell> rpm -qpl MySQL-server-VERSION.glibc23.i386.rpm

To perform a standard minimal installation, install the server and
client RPMs:

     shell> rpm -i MySQL-server-VERSION.glibc23.i386.rpm
     shell> rpm -i MySQL-client-VERSION.glibc23.i386.rpm

To install only the client programs, install just the client RPM:

     shell> rpm -i MySQL-client-VERSION.glibc23.i386.rpm

RPM provides a feature to verify the integrity and authenticity of
packages before installing them. If you would like to learn more about
this feature, see *Note verifying-package-integrity::.

The server RPM places data under the `/var/lib/mysql' directory. The
RPM also creates a login account for a user named `mysql' (if one does
not exist) to use for running the MySQL server, and creates the
appropriate entries in `/etc/init.d/' to start the server automatically
at boot time. (This means that if you have performed a previous
installation and have made changes to its startup script, you may want
to make a copy of the script so that you don't lose it when you install
a newer RPM.) See *Note automatic-start::, for more information on how
MySQL can be started automatically on system startup.

If you want to install the MySQL RPM on older Linux distributions that
do not support initialization scripts in `/etc/init.d' (directly or via
a symlink), you should create a symbolic link that points to the
location where your initialization scripts actually are installed. For
example, if that location is `/etc/rc.d/init.d', use these commands
before installing the RPM to create `/etc/init.d' as a symbolic link
that points there:

     shell> cd /etc
     shell> ln -s rc.d/init.d .

However, all current major Linux distributions should support the new
directory layout that uses `/etc/init.d', because it is required for
LSB (Linux Standard Base) compliance.

If the RPM files that you install include `MySQL-server', the `mysqld'
server should be up and running after installation. You should be able
to start using MySQL.

If something goes wrong, you can find more information in the binary
installation section. See *Note installing-binary::.

*Note*:

The accounts that are listed in the MySQL grant tables initially have
no passwords. After starting the server, you should set up passwords
for them using the instructions in *Note post-installation::.


File: manual.info,  Node: mac-os-x-installation,  Next: solaris-installation,  Prev: linux-rpm,  Up: installing

2.5 Installing MySQL on Mac OS X
================================

You can install MySQL on Mac OS X 10.3.x (`Panther') or newer using a
Mac OS X binary package in PKG format instead of the binary tarball
distribution. Please note that older versions of Mac OS X (for example,
10.1.x or 10.2.x) are *not* supported by this package.

The package is located inside a disk image (`.dmg') file that you first
need to mount by double-clicking its icon in the Finder. It should then
mount the image and display its contents.

To obtain MySQL, see *Note getting-mysql::.

*Note*:

Before proceeding with the installation, be sure to shut down all
running MySQL server instances by either using the MySQL Manager
Application (on Mac OS X Server) or via `mysqladmin shutdown' on the
command line.

To actually install the MySQL PKG file, double-click on the package
icon. This launches the Mac OS X Package Installer, which guides you
through the installation of MySQL.

Due to a bug in the Mac OS X package installer, you may see this error
message in the destination disk selection dialog:

     You cannot install this software on this disk. (null)

If this error occurs, simply click the `Go Back' button once to return
to the previous screen. Then click `Continue' to advance to the
destination disk selection again, and you should be able to choose the
destination disk correctly. We have reported this bug to Apple and it is
investigating this problem.

The Mac OS X PKG of MySQL installs itself into
`/usr/local/mysql-VERSION' and also installs a symbolic link,
`/usr/local/mysql', that points to the new location. If a directory
named `/usr/local/mysql' exists, it is renamed to
`/usr/local/mysql.bak' first. Additionally, the installer creates the
grant tables in the `mysql' database by executing `mysql_install_db'.

The installation layout is similar to that of a `tar' file binary
distribution; all MySQL binaries are located in the directory
`/usr/local/mysql/bin'. The MySQL socket file is created as
`/tmp/mysql.sock' by default. See *Note installation-layouts::.

MySQL installation requires a Mac OS X user account named `mysql'. A
user account with this name should exist by default on Mac OS X 10.2
and up.

If you are running Mac OS X Server, a version of MySQL should already
be installed. The following table shows the versions of MySQL that ship
with Mac OS X Server versions.

*Mac OS X Server       *MySQL Version*
Version*               
10.2-10.2.2            3.23.51
10.2.3-10.2.6          3.23.53
10.3                   4.0.14
10.3.2                 4.0.16
10.4.0                 4.1.10a

This manual section covers the installation of the official MySQL Mac
OS X PKG only. Make sure to read Apple's help information about
installing MySQL: Run the `Help View' application, select `Mac OS X
Server' help, do a search for `MySQL,' and read the item entitled
`Installing MySQL.'

If you previously used Marc Liyanage's MySQL packages for Mac OS X from
`http://www.entropy.ch', you can simply follow the update instructions
for packages using the binary installation layout as given on his pages.

If you are upgrading from Marc's 3.23.x versions or from the Mac OS X
Server version of MySQL to the official MySQL PKG, you also need to
convert the existing MySQL privilege tables to the current format,
because some new security privileges have been added. See *Note
mysql-upgrade::.

If you want MySQL to start automatically during system startup, you
also need to install the MySQL Startup Item. It is part of the Mac OS X
installation disk images as a separate installation package. Simply
double-click the `MySQLStartupItem.pkg' icon and follow the
instructions to install it. The Startup Item need be installed only
once. There is no need to install it each time you upgrade the MySQL
package later.

The Startup Item for MySQL is installed into
`/Library/StartupItems/MySQLCOM'. (Before MySQL 4.1.2, the location was
`/Library/StartupItems/MySQL', but that collided with the MySQL Startup
Item installed by Mac OS X Server.) Startup Item installation adds a
variable `MYSQLCOM=-YES-' to the system configuration file
`/etc/hostconfig'. If you want to disable the automatic startup of
MySQL, simply change this variable to `MYSQLCOM=-NO-'.

On Mac OS X Server, the default MySQL installation uses the variable
`MYSQL' in the `/etc/hostconfig' file. The MySQL AB Startup Item
installer disables this variable by setting it to `MYSQL=-NO-'. This
avoids boot time conflicts with the `MYSQLCOM' variable used by the
MySQL AB Startup Item. However, it does not shut down a running MySQL
server. You should do that yourself.

After the installation, you can start up MySQL by running the following
commands in a terminal window. You must have administrator privileges
to perform this task.

If you have installed the Startup Item, use this command:

     shell> sudo /Library/StartupItems/MySQLCOM/MySQLCOM start
     (ENTER YOUR PASSWORD, IF NECESSARY)
     (PRESS CONTROL-D OR ENTER "EXIT" TO EXIT THE SHELL)

If you don't use the Startup Item, enter the following command sequence:

     shell> cd /usr/local/mysql
     shell> sudo ./bin/mysqld_safe
     (ENTER YOUR PASSWORD, IF NECESSARY)
     (PRESS CONTROL-Z)
     shell> bg
     (PRESS CONTROL-D OR ENTER "EXIT" TO EXIT THE SHELL)

You should be able to connect to the MySQL server, for example, by
running `/usr/local/mysql/bin/mysql'.

*Note*:

The accounts that are listed in the MySQL grant tables initially have
no passwords. After starting the server, you should set up passwords
for them using the instructions in *Note post-installation::.

You might want to add aliases to your shell's resource file to make it
easier to access commonly used programs such as `mysql' and
`mysqladmin' from the command line. The syntax for `bash' is:

     alias mysql=/usr/local/mysql/bin/mysql
     alias mysqladmin=/usr/local/mysql/bin/mysqladmin

For `tcsh', use:

     alias mysql /usr/local/mysql/bin/mysql
     alias mysqladmin /usr/local/mysql/bin/mysqladmin

Even better, add `/usr/local/mysql/bin' to your `PATH' environment
variable. You can do this by modifying the appropriate startup file for
your shell. For more information, see *Note invoking-programs::.

If you are upgrading an existing installation, note that installing a
new MySQL PKG does not remove the directory of an older installation.
Unfortunately, the Mac OS X Installer does not yet offer the
functionality required to properly upgrade previously installed
packages.

To use your existing databases with the new installation, you'll need
to copy the contents of the old data directory to the new data
directory. Make sure that neither the old server nor the new one is
running when you do this. After you have copied over the MySQL database
files from the previous installation and have successfully started the
new server, you should consider removing the old installation files to
save disk space. Additionally, you should also remove older versions of
the Package Receipt directories located in
`/Library/Receipts/mysql-VERSION.pkg'.


File: manual.info,  Node: solaris-installation,  Next: netware-installation,  Prev: mac-os-x-installation,  Up: installing

2.6 Installing MySQL on Solaris
===============================

If you install MySQL using a binary tarball distribution on Solaris,
you may run into trouble even before you get the MySQL distribution
unpacked, as the Solaris `tar' cannot handle long filenames. This means
that you may see errors when you try to unpack MySQL.

If this occurs, you must use GNU `tar' (`gtar') to unpack the
distribution. You can find a precompiled copy for Solaris at
`http://dev.mysql.com/downloads/os-solaris.html'.

You can install MySQL on Solaris using a binary package in PKG format
instead of the binary tarball distribution. Before installing using the
binary PKG format, you should create the `mysql' user and group, for
example:

     groupadd mysql
     useradd -g mysql mysql

Some basic PKG-handling commands follow:

   * To add a package:

          pkgadd -d PACKAGE_NAME.pkg

   * To remove a package:

          pkgrm PACKAGE_NAME

   * To get a full list of installed packages:

          pkginfo

   * To get detailed information for a package:

          pkginfo -l PACKAGE_NAME

   * To list the files belonging to a package:

          pkgchk -v PACKAGE_NAME

   * To get packaging information for an arbitrary file:

          pkgchk -l -p FILE_NAME

For additional information about installing MySQL on Solaris, see *Note
solaris::.


File: manual.info,  Node: netware-installation,  Next: installing-binary,  Prev: solaris-installation,  Up: installing

2.7 Installing MySQL on NetWare
===============================

Porting MySQL to NetWare was an effort spearheaded by Novell.  Novell
customers should be pleased to note that NetWare 6.5 ships with bundled
MySQL binaries, complete with an automatic commercial use license for
all servers running that version of NetWare.

MySQL for NetWare is compiled using a combination of Metrowerks
CodeWarrior for NetWare and special cross-compilation versions of the
GNU autotools.

The latest binary packages for NetWare can be obtained at
`http://dev.mysql.com/downloads/'. See *Note getting-mysql::.

To host MySQL, the NetWare server must meet these requirements:

   * The latest Support Pack of NetWare 6.5
     (http://support.novell.com/filefinder/18197/index.html) must be
     installed.

   * The system must meet Novell's minimum requirements to run the
     respective version of NetWare.

   * MySQL data and the program binaries must be installed on an NSS
     volume; traditional volumes are not supported.

To install MySQL for NetWare, use the following procedure:

  1. If you are upgrading from a prior installation, stop the MySQL
     server. This is done from the server console, using the following
     command:

          SERVER:  mysqladmin -u root shutdown

     *Note*:

     If the MySQL `root' user account has a password, you need to
     invoke `mysqladmin' with the `-p' option and supply the password
     when prompted.

  2. Log on to the target server from a client machine with access to
     the location where you are installing MySQL.

  3. Extract the binary package Zip file onto the server. Be sure to
     allow the paths in the Zip file to be used. It is safe to simply
     extract the file to `SYS:\'.

     If you are upgrading from a prior installation, you may need to
     copy the data directory (for example, `SYS:MYSQL\DATA'), as well as
     `my.cnf', if you have customized it. You can then delete the old
     copy of MySQL.

  4. You might want to rename the directory to something more
     consistent and easy to use. The examples in this manual use
     `SYS:MYSQL' to refer to the installation directory.

     Note that MySQL installation on NetWare does not detect if a
     version of MySQL is already installed outside the NetWare release.
     Therefore, if you have installed the latest MySQL version from the
     Web (for example, MySQL 4.1 or later) in `SYS:\MYSQL', you must
     rename the folder before upgrading the NetWare server; otherwise,
     files in `SYS:\MySQL' are overwritten by the MySQL version present
     in NetWare Support Pack.

  5. At the server console, add a search path for the directory
     containing the MySQL NLMs. For example:

          SERVER:  SEARCH ADD SYS:MYSQL\BIN

  6. Initialize the data directory and the grant tables, if necessary,
     by executing `mysql_install_db' at the server console.

  7. Start the MySQL server using `mysqld_safe' at the server console.

  8. To finish the installation, you should also add the following
     commands to `autoexec.ncf'. For example, if your MySQL
     installation is in `SYS:MYSQL' and you want MySQL to start
     automatically, you could add these lines:

          #Starts the MySQL 5.1.x database server
          SEARCH ADD SYS:MYSQL\BIN
          MYSQLD_SAFE

     If you are running MySQL on NetWare 6.0, we strongly suggest that
     you use the `--skip-external-locking' option on the command line:

          #Starts the MySQL 5.1.x database server
          SEARCH ADD SYS:MYSQL\BIN
          MYSQLD_SAFE --skip-external-locking

     It is also necessary to use `CHECK TABLE' and `REPAIR TABLE'
     instead of `myisamchk', because `myisamchk' makes use of external
     locking.  External locking is known to have problems on NetWare
     6.0; the problem has been eliminated in NetWare 6.5. Note that the
     use of MySQL on Netware 6.0 is not officially supported.

     `mysqld_safe' on NetWare provides a screen presence. When you
     unload (shut down) the `mysqld_safe' NLM, the screen does not go
     away by default. Instead, it prompts for user input:

          *<NLM has terminated; Press any key to close the screen>*

     If you want NetWare to close the screen automatically instead, use
     the `--autoclose' option to `mysqld_safe'. For example:

          #Starts the MySQL 5.1.x database server
          SEARCH ADD SYS:MYSQL\BIN
          MYSQLD_SAFE --autoclose

     The behavior of `mysqld_safe' on NetWare is described further in
     *Note mysqld-safe::.

  9. When installing MySQL, either for the first time or upgrading from
     a previous version, download and install the latest and
     appropriate Perl module and PHP extensions for NetWare:

        * Perl:
          `http://forge.novell.com/modules/xfcontent/downloads.php/perl/Modules/'

        * PHP:
          `http://forge.novell.com/modules/xfcontent/downloads.php/php/Modules/'

If there was an existing installation of MySQL on the NetWare server,
be sure to check for existing MySQL startup commands in `autoexec.ncf',
and edit or delete them as necessary.

*Note*:

The accounts that are listed in the MySQL grant tables initially have
no passwords. After starting the server, you should set up passwords
for them using the instructions in *Note post-installation::.


File: manual.info,  Node: installing-binary,  Next: installing-source,  Prev: netware-installation,  Up: installing

2.8 Installing MySQL from `tar.gz' Packages on Other Unix-Like Systems
======================================================================

This section covers the installation of MySQL binary distributions that
are provided for various platforms in the form of compressed `tar'
files (files with a `.tar.gz' extension). See *Note mysql-binaries::,
for a detailed list.

To obtain MySQL, see *Note getting-mysql::.

MySQL `tar' file binary distributions have names of the form
`mysql-VERSION-OS.tar.gz', where `VERSION' is a number (for example,
`5.1.28'), and OS indicates the type of operating system for which the
distribution is intended (for example, `pc-linux-i686').

In addition to these generic packages, we also offer binaries in
platform-specific package formats for selected platforms. See *Note
quick-standard-installation::, for more information on how to install
these.

You need the following tools to install a MySQL `tar' file binary
distribution:

   * GNU `gunzip' to uncompress the distribution.

   * A reasonable `tar' to unpack the distribution. GNU `tar' is known
     to work.  Some operating systems come with a preinstalled version
     of `tar' that is known to have problems. For example, the `tar'
     provided with early versions of Mac OS X, SunOS 4.x and Solaris 8
     and earlier are known to have problems with long filenames. On Mac
     OS X, you can use the preinstalled `gnutar' program. On other
     systems with a deficient `tar', you should install GNU `tar' first.

If you run into problems and need to file a bug report, please use the
instructions in *Note bug-reports::.

The basic commands that you must execute to install and use a MySQL
binary distribution are:

     shell> groupadd mysql
     shell> useradd -g mysql mysql
     shell> cd /usr/local
     shell> gunzip < /PATH/TO/MYSQL-VERSION-OS.tar.gz | tar xvf -
     shell> ln -s FULL-PATH-TO-MYSQL-VERSION-OS mysql
     shell> cd mysql
     shell> chown -R mysql .
     shell> chgrp -R mysql .
     shell> scripts/mysql_install_db --user=mysql
     shell> chown -R root .
     shell> chown -R mysql data
     shell> bin/mysqld_safe --user=mysql &

*Note*:

This procedure does not set up any passwords for MySQL accounts.  After
following the procedure, proceed to *Note post-installation::.

A more detailed version of the preceding description for installing a
binary distribution follows:

  1. Add a login user and group for `mysqld' to run as:

          shell> groupadd mysql
          shell> useradd -g mysql mysql

     These commands add the `mysql' group and the `mysql' user. The
     syntax for `useradd' and `groupadd' may differ slightly on
     different versions of Unix, or they may have different names such
     as `adduser' and `addgroup'.

     You might want to call the user and group something else instead
     of `mysql'. If so, substitute the appropriate name in the
     following steps.

  2. Pick the directory under which you want to unpack the distribution
     and change location into it. In the following example, we unpack
     the distribution under `/usr/local'. (The instructions, therefore,
     assume that you have permission to create files and directories in
     `/usr/local'. If that directory is protected, you must perform the
     installation as `root'.)

          shell> cd /usr/local

  3. Obtain a distribution file using the instructions in *Note
     getting-mysql::. For a given release, binary distributions for all
     platforms are built from the same MySQL source distribution.

  4. Unpack the distribution, which creates the installation directory.
     Then create a symbolic link to that directory:

          shell> gunzip < /PATH/TO/MYSQL-VERSION-OS.tar.gz | tar xvf -
          shell> ln -s FULL-PATH-TO-MYSQL-VERSION-OS mysql

     The `tar' command creates a directory named `mysql-VERSION-OS'.
     The `ln' command makes a symbolic link to that directory. This
     lets you refer more easily to the installation directory as
     `/usr/local/mysql'.

     With GNU `tar', no separate invocation of `gunzip' is necessary.
     You can replace the first line with the following alternative
     command to uncompress and extract the distribution:

          shell> tar zxvf /PATH/TO/MYSQL-VERSION-OS.tar.gz

  5. Change location into the installation directory:

          shell> cd mysql

     You will find several files and subdirectories in the `mysql'
     directory. The most important for installation purposes are the
     `bin' and `scripts' subdirectories:

        * The `bin' directory contains client programs and the server.
          You should add the full pathname of this directory to your
          `PATH' environment variable so that your shell finds the MySQL
          programs properly. See *Note environment-variables::.

        * The `scripts' directory contains the `mysql_install_db'
          script used to initialize the `mysql' database containing the
          grant tables that store the server access permissions.

  6. Ensure that the distribution contents are accessible to `mysql'.
     If you unpacked the distribution as `mysql', no further action is
     required. If you unpacked the distribution as `root', its contents
     will be owned by `root'. Change its ownership to `mysql' by
     executing the following commands as `root' in the installation
     directory:

          shell> chown -R mysql .
          shell> chgrp -R mysql .

     The first command changes the owner attribute of the files to the
     `mysql' user. The second changes the group attribute to the
     `mysql' group.

  7. If you have not installed MySQL before, you must create the MySQL
     data directory and initialize the grant tables:

          shell> scripts/mysql_install_db --user=mysql

     If you run the command as `root', include the `--user' option as
     shown. If you run the command while logged in as that user, you
     can omit the `--user' option.

     The command should create the data directory and its contents with
     `mysql' as the owner.

     After creating or updating the grant tables, you need to restart
     the server manually.

  8. Most of the MySQL installation can be owned by `root' if you like.
     The exception is that the data directory must be owned by `mysql'.
     To accomplish this, run the following commands as `root' in the
     installation directory:

          shell> chown -R root .
          shell> chown -R mysql data

  9. If you want MySQL to start automatically when you boot your
     machine, you can copy `support-files/mysql.server' to the location
     where your system has its startup files. More information can be
     found in the `support-files/mysql.server' script itself and in
     *Note automatic-start::.

 10. You can set up new accounts using the `bin/mysql_setpermission'
     script if you install the `DBI' and `DBD::mysql' Perl modules. See
     *Note mysql-setpermission::. For Perl module installation
     instructions, see *Note perl-support::.

 11. If you would like to use `mysqlaccess' and have the MySQL
     distribution in some non-standard location, you must change the
     location where `mysqlaccess' expects to find the `mysql' client.
     Edit the `bin/mysqlaccess' script at approximately line 18. Search
     for a line that looks like this:

          $MYSQL     = '/usr/local/bin/mysql';    # path to mysql executable

     Change the path to reflect the location where `mysql' actually is
     stored on your system. If you do not do this, a `Broken pipe' error
     will occur when you run `mysqlaccess'.

After everything has been unpacked and installed, you should test your
distribution. To start the MySQL server, use the following command:

     shell> bin/mysqld_safe --user=mysql &

If you run the command as `root', you must use the `--user' option as
shown. The value of the option is the name of the login account that
you created in the first step to use for running the server. If you run
the command while logged in as `mysql', you can omit the `--user'
option.

If the command fails immediately and prints `mysqld ended', you can
find some information in the `HOST_NAME.err' file in the data directory.

More information about `mysqld_safe' is given in *Note mysqld-safe::.

*Note*:

The accounts that are listed in the MySQL grant tables initially have
no passwords. After starting the server, you should set up passwords
for them using the instructions in *Note post-installation::.


File: manual.info,  Node: installing-source,  Next: post-installation,  Prev: installing-binary,  Up: installing

2.9 MySQL Installation Using a Source Distribution
==================================================

* Menu:

* quick-install::                Source Installation Overview
* configure-options::            Typical `configure' Options
* installing-source-tree::       Installing from the Development Source Tree
* compilation-problems::         Dealing with Problems Compiling MySQL
* mit-pthreads::                 MIT-pthreads Notes
* windows-source-build::         Installing MySQL from Source on Windows
* windows-client-compiling::     Compiling MySQL Clients on Windows

Before you proceed with an installation from source, first check
whether our binary is available for your platform and whether it works
for you. We put a great deal of effort into ensuring that our binaries
are built with the best possible options.

To obtain a source distribution for MySQL, *Note getting-mysql::. If
you want to build MySQL from source on Windows, see *Note
windows-source-build::.

MySQL source distributions are provided as compressed `tar' archives
and have names of the form `mysql-VERSION.tar.gz', where VERSION is a
number like `5.1.28'.

You need the following tools to build and install MySQL from source:

   * GNU `gunzip' to uncompress the distribution.

   * A reasonable `tar' to unpack the distribution. GNU `tar' is known
     to work.  Some operating systems come with a preinstalled version
     of `tar' that is known to have problems. For example, the `tar'
     provided with early versions of Mac OS X, SunOS 4.x and Solaris 8
     and earlier are known to have problems with long filenames. On Mac
     OS X, you can use the preinstalled `gnutar' program. On other
     systems with a deficient `tar', you should install GNU `tar' first.

   * A working ANSI C++ compiler. `gcc' 2.95.2 or later, SGI C++, and
     SunPro C++ are some of the compilers that are known to work.
     `libg++' is not needed when using `gcc'. `gcc' 2.7.x has a bug
     that makes it impossible to compile some perfectly legal C++
     files, such as `sql/sql_base.cc'. If you have only `gcc' 2.7.x,
     you must upgrade your `gcc' to be able to compile MySQL.  `gcc'
     2.8.1 is also known to have problems on some platforms, so it
     should be avoided if a newer compiler exists for the platform.
     `gcc' 2.95.2 or later is recommended.

   * A good `make' program. GNU `make' is always recommended and is
     sometimes required. (BSD `make' fails, and vendor-provided `make'
     implementations may fail as well.) If you have problems, we
     recommend GNU `make' 3.75 or newer.

   * `libtool' 1.5.24 or later is also recommended.

If you are using a version of `gcc' recent enough to understand the
`-fno-exceptions' option, it is _very important_ that you use this
option.  Otherwise, you may compile a binary that crashes randomly. We
also recommend that you use `-felide-constructors' and `-fno-rtti'
along with `-fno-exceptions'. When in doubt, do the following:

     CFLAGS="-O3" CXX=gcc CXXFLAGS="-O3 -felide-constructors \
            -fno-exceptions -fno-rtti" ./configure \
            --prefix=/usr/local/mysql --enable-assembler \
            --with-mysqld-ldflags=-all-static

On most systems, this gives you a fast and stable binary.

If you run into problems and need to file a bug report, please use the
instructions in *Note bug-reports::.


File: manual.info,  Node: quick-install,  Next: configure-options,  Prev: installing-source,  Up: installing-source

2.9.1 Source Installation Overview
----------------------------------

The basic commands that you must execute to install a MySQL source
distribution are:

     shell> groupadd mysql
     shell> useradd -g mysql mysql
     shell> gunzip < mysql-VERSION.tar.gz | tar -xvf -
     shell> cd mysql-VERSION
     shell> ./configure --prefix=/usr/local/mysql
     shell> make
     shell> make install
     shell> cp support-files/my-medium.cnf /etc/my.cnf
     shell> cd /usr/local/mysql
     shell> chown -R mysql .
     shell> chgrp -R mysql .
     shell> bin/mysql_install_db --user=mysql
     shell> chown -R root .
     shell> chown -R mysql var
     shell> bin/mysqld_safe --user=mysql &

If you start from a source RPM, do the following:

     shell> rpmbuild --rebuild --clean MySQL-VERSION.src.rpm

This makes a binary RPM that you can install. For older versions of
RPM, you may have to replace the command `rpmbuild' with `rpm' instead.

*Note*:

This procedure does not set up any passwords for MySQL accounts. After
following the procedure, proceed to *Note post-installation::, for
post-installation setup and testing.

A more detailed version of the preceding description for installing
MySQL from a source distribution follows:

  1. Add a login user and group for `mysqld' to run as:

          shell> groupadd mysql
          shell> useradd -g mysql mysql

     These commands add the `mysql' group and the `mysql' user. The
     syntax for `useradd' and `groupadd' may differ slightly on
     different versions of Unix, or they may have different names such
     as `adduser' and `addgroup'.

     You might want to call the user and group something else instead
     of `mysql'. If so, substitute the appropriate name in the
     following steps.

  2. Perform the following steps as the `mysql' user, except as noted.

  3. Pick the directory under which you want to unpack the distribution
     and change location into it.

  4. Obtain a distribution file using the instructions in *Note
     getting-mysql::.

  5. Unpack the distribution into the current directory:

          shell> gunzip < /PATH/TO/MYSQL-VERSION.tar.gz | tar xvf -

     This command creates a directory named `mysql-VERSION'.

     With GNU `tar', no separate invocation of `gunzip' is necessary.
     You can use the following alternative command to uncompress and
     extract the distribution:

          shell> tar zxvf /PATH/TO/MYSQL-VERSION-OS.tar.gz

  6. Change location into the top-level directory of the unpacked
     distribution:

          shell> cd mysql-VERSION

     Note that currently you must configure and build MySQL from this
     top-level directory. You cannot build it in a different directory.

  7. Configure the release and compile everything:

          shell> ./configure --prefix=/usr/local/mysql
          shell> make

     When you run `configure', you might want to specify other options.
     Run `./configure --help' for a list of options.  *Note
     configure-options::, discusses some of the more useful options.

     If `configure' fails and you are going to send mail to a MySQL
     mailing list to ask for assistance, please include any lines from
     `config.log' that you think can help solve the problem. Also
     include the last couple of lines of output from `configure'. To
     file a bug report, please use the instructions in *Note
     bug-reports::.

     If the compile fails, see *Note compilation-problems::, for help.

  8. Install the distribution:

          shell> make install

     You might need to run this command as `root'.

     If you want to set up an option file, use one of those present in
     the `support-files' directory as a template. For example:

          shell> cp support-files/my-medium.cnf /etc/my.cnf

     You might need to run this command as `root'.

     If you want to configure support for `InnoDB' tables, you should
     edit the `/etc/my.cnf' file, remove the `#' character before the
     option lines that start with `innodb_...', and modify the option
     values to be what you want. See *Note option-files::, and *Note
     innodb-configuration::.

  9. Change location into the installation directory:

          shell> cd /usr/local/mysql

 10. If you ran the `make install' command as `root', the installed
     files will be owned by `root'. Ensure that the installation is
     accessible to `mysql' by executing the following commands as
     `root' in the installation directory:

          shell> chown -R mysql .
          shell> chgrp -R mysql .

     The first command changes the owner attribute of the files to the
     `mysql' user. The second changes the group attribute to the
     `mysql' group.

 11. If you have not installed MySQL before, you must create the MySQL
     data directory and initialize the grant tables:

          shell> bin/mysql_install_db --user=mysql

     If you run the command as `root', include the `--user' option as
     shown. If you run the command while logged in as `mysql', you can
     omit the `--user' option.

     The command should create the data directory and its contents with
     `mysql' as the owner.

     After using `mysql_install_db' to create the grant tables for
     MySQL, you must restart the server manually. The `mysqld_safe'
     command to do this is shown in a later step.

 12. Most of the MySQL installation can be owned by `root' if you like.
     The exception is that the data directory must be owned by `mysql'.
     To accomplish this, run the following commands as `root' in the
     installation directory:

          shell> chown -R root .
          shell> chown -R mysql var

 13. If you want MySQL to start automatically when you boot your
     machine, you can copy `support-files/mysql.server' to the location
     where your system has its startup files. More information can be
     found in the `support-files/mysql.server' script itself; see also
     *Note automatic-start::.

 14. You can set up new accounts using the `bin/mysql_setpermission'
     script if you install the `DBI' and `DBD::mysql' Perl modules. See
     *Note mysql-setpermission::. For Perl module installation
     instructions, see *Note perl-support::.

After everything has been installed, you should test your distribution.
To start the MySQL server, use the following command:

     shell> /usr/local/mysql/bin/mysqld_safe --user=mysql &

If you run the command as `root', you should use the `--user' option as
shown. The value of the option is the name of the login account that
you created in the first step to use for running the server. If you run
the command while logged in as that user, you can omit the `--user'
option.

If the command fails immediately and prints `mysqld ended', you can
find some information in the `HOST_NAME.err' file in the data directory.

More information about `mysqld_safe' is given in *Note mysqld-safe::.

*Note*:

The accounts that are listed in the MySQL grant tables initially have
no passwords. After starting the server, you should set up passwords
for them using the instructions in *Note post-installation::.


File: manual.info,  Node: configure-options,  Next: installing-source-tree,  Prev: quick-install,  Up: installing-source

2.9.2 Typical `configure' Options
---------------------------------

The `configure' script gives you a great deal of control over how you
configure a MySQL source distribution.  Typically you do this using
options on the `configure' command line. You can also affect
`configure' using certain environment variables. See *Note
environment-variables::. For a full list of options supported by
`configure', run this command:

     shell> ./configure --help

A list of the available `configure' options is provided in the table
below.

*Build (`configure') Reference*

*Formats*              *Description*          *Default*      *Introduced**Removed*
-bindir=DIR            User executables       EPREFIX/bin            
-build=BUILD           Configure for          guessed                
                       building on BUILD                             
-cache-file=FILE       Cache test results in  disabled               
                       FILE                                          
-C                     Alias for                                     
                       `-cache-file=config.cache'                       
-config-cache                                                        
-datadir=DIR           Read-only              PREFIX/share           
                       architecture-independent                       
                       data                                          
-disable-FEATURE       Do not include FEATURE                        
-disable-dependency-trackingDisable dependency                            
                       tracking                                      
-disable-grant-options Disable GRANT options                         
-disable-largefile     Omit support for                              
                       large files                                   
-disable-libtool-lock  Disable libtool lock                          
-disable-thread-safe-clientCompile the client                    5.1.7   
                       without threads                               
-enable-FEATURE        Enable FEATURE                                
-enable-assembler      Use assembler                                 
                       versions of some                              
                       string functions if                           
                       available                                     
-enable-dependency-trackingDo not reject slow                            
                       dependency extractors                         
-enable-fast-install   Optimize for fast      yes                    
                       installation                                  
-enable-local-infile   Enable LOAD DATA       disabled               
                       LOCAL INFILE                                  
-enable-shared         Build shared libraries yes                    
-enable-static         Build static libraries yes                    
-enable-thread-safe-clientCompile the client                            
                       with threads                                  
-exec-prefix=EPREFIX   Install                                       
                       architecture-dependent                        
                       files in EPREFIX                              
-h                     Display this help and                         
                       exit                                          
-help                                                                
-help=short            Display options                               
                       specific to this                              
                       package                                       
-help=recursive        Display the short                             
                       help of all the                               
                       included packages                             
-host=HOST             Cross-compile to                              
                       build programs to run                         
                       on HOST                                       
-includedir=DIR        C header files         PREFIX/include         
-infodir=DIR           Info documentation     PREFIX/info            
-libdir=DIR            Object code libraries  EPREFIX/lib            
-libexecdir=DIR        Program executables    EPREFIX/libexec        
-localstatedir=DIR     Modifiable             PREFIX/var             
                       single-machine data                           
-mandir=DIR            man documentation      PREFIX/man             
-n                     Do not create output                          
                       files                                         
-no-create                                                           
-oldincludedir=DIR     C header files for     /usr/include           
                       non-gcc                                       
-prefix=PREFIX         Install                                       
                       architecture-independent                       
                       files in PREFIX                               
-program-prefix=PREFIX Prepend PREFIX to                             
                       installed program                             
                       names                                         
-program-suffix=SUFFIX Append SUFFIX to                              
                       installed program                             
                       names                                         
-program-transform-name=PROGRAMrun sed PROGRAM on                            
                       installed program                             
                       names                                         
-q                     Do not print                                  
                       `checking...' messages                        
-quiet                                                               
-sbindir=DIR           System admin           EPREFIX/sbin           
                       executables                                   
-sharedstatedir=DIR    Modifiable             PREFIX/com             
                       architecture-independent                       
                       data                                          
-srcdir=DIR            Find the sources in    configure              
                       DIR                    directory or           
                                              ..                     
-sysconfdir=DIR        Read-only              PREFIX/etc             
                       single-machine data                           
-target=TARGET         Configure for                                 
                       building compilers                            
                       for TARGET                                    
-V                     Display version                               
                       information and exit                          
-version                                                             
-with-PACKAGE          Use PACKAGE                                   
-with-archive-storage-engineEnable the Archive     no                     
                       Storage Engine                                
-with-atomic-ops       Implement atomic                      5.1.12  
                       operations using                              
                       pthread rwlocks or                            
                       atomic CPU                                    
                       instructions for                              
                       multi-processor                               
-with-berkeley-db      Use BerkeleyDB         no                     
                       located in DIR                                
-with-berkeley-db-includesFind Berkeley DB                              
                       headers in DIR                                
-with-berkeley-db-libs Find Berkeley DB                              
                       libraries in DIR                              
-with-big-tables       Support tables with                           
                       more than 4 G rows                            
                       even on 32 bit                                
                       platforms                                     
-with-blackhole-storage-engineEnable the Blackhole   no                     
                       Storage Engine                                
-with-charset          Default character set                         
-with-client-ldflags   Extra linking                                 
                       arguments for clients                         
-with-collation        Default collation                             
-with-comment          Comment about                                 
                       compilation                                   
                       environment                                   
-with-csv-storage-engineEnable the CSV         yes                    
                       Storage Engine                                
-with-darwin-mwcc      Use Metrowerks                                
                       CodeWarrior wrappers                          
                       on OS X/Darwin                                
-with-debug            Add debug code                        5.1.7   
-with-debug=full       Add debug code (adds                          
                       memory checker, very                          
                       slow)                                         
-with-embedded-privilege-controlBuild parts to check                          
                       user's privileges                             
                       (only affects                                 
                       embedded library)                             
-with-embedded-server  Build the embedded                            
                       server                                        
-with-error-inject     Enable error                          5.1.11  
                       injection in MySQL                            
                       Server                                        
-with-example-storage-engineEnable the Example     no                     
                       Storage Engine                                
-with-extra-charsets   Use charsets in                               
                       addition to default                           
-with-fast-mutexes     Compile with fast      enabled        5.1.5   
                       mutexes                                       
-with-federated-storage-engineEnable federated       no             5.1.3   5.1.9
                       storage engine                                
-with-gnu-ld           Assume the C compiler  no                     
                       uses GNU ld                                   
-with-innodb           Enable innobase        no             5.1.3   5.1.9
                       storage engine                                
-with-lib-ccflags      Extra CC options for                          
                       libraries                                     
-with-libwrap=DIR      Compile in libwrap                            
                       (tcp_wrappers) support                        
-with-low-memory       Try to use less                               
                       memory to compile to                          
                       avoid memory                                  
                       limitations                                   
-with-machine-type     Set the machine type,                         
                       like "powerpc"                                
-with-max-indexes=N    Sets the maximum       64                     
                       number of indexes per                         
                       table                                         
-with-mysqld-ldflags   Extra linking                                 
                       arguments for mysqld                          
-with-mysqld-libs      Extra libraries to                            
                       link with for mysqld                          
-with-mysqld-user      What user the mysqld                          
                       daemon shall be run as                        
-with-mysqlmanager     Build the              Build if               
                       mysqlmanager binary    server is              
                                              built                  
-with-named-curses-libsUse specified curses                          
                       libraries                                     
-with-named-thread-libsUse specified thread                          
                       libraries                                     
-with-ndb-ccflags      Extra CC options for                          
                       ndb compile                                   
-with-ndb-docs         Include the NDB                               
                       Cluster ndbapi and                            
                       mgmapi documentation                          
-with-ndb-port         Port for NDB Cluster                          
                       management server                             
-with-ndb-port-base    Port for NDB Cluster                          
                       management server                             
-with-ndb-sci=DIR      Provide MySQL with a                          
                       custom location of                            
                       sci library                                   
-with-ndb-test         Include the NDB                               
                       Cluster ndbapi test                           
                       programs                                      
-with-ndbcluster       Include the NDB        no                     
                       Cluster table handler                         
-with-openssl=DIR      Include the OpenSSL                           
                       support                                       
-with-openssl-includes Find OpenSSL headers                          
                       in DIR                                        
-with-openssl-libs     Find OpenSSL                                  
                       libraries in DIR                              
-with-other-libc=DIR   Link against libc and                         
                       other standard                                
                       libraries installed                           
                       in the specified                              
                       non-standard location                         
-with-pic              Try to use only        Use both               
                       PIC/non-PIC objects                           
-with-plugin-PLUGIN    Forces the named                      5.1.11  
                       plugin to be linked                           
                       into mysqld statically                        
-with-plugins          Plugins to include in  none           5.1.11  
                       mysqld                                        
-with-pstack           Use the pstack                                
                       backtrace library                             
-with-pthread          Force use of pthread                          
                       library                                       
-with-row-based-replicationInclude row-based                     5.1.5   5.1.6
                       replication                                   
-with-server-suffix    Append value to the                           
                       version string                                
-with-ssl=DIR          Include SSL support                   5.1.11  
-with-system-type      Set the system type,                          
                       like "sun-solaris10"                          
-with-tags             Include additional     automatic              
                       configurations                                
-with-tcp-port         Which port to use for  3306                   
                       MySQL services                                
-with-unix-socket-path Where to put the                              
                       unix-domain socket                            
-with-yassl            Include the yaSSL                             
                       support                                       
-with-zlib-dir=no|bundled|DIRProvide MySQL with a                          
                       custom location of                            
                       compression library                           
-without-PACKAGE       Do not use PACKAGE                            
-without-bench         Skip building of the                          
                       benchmark suite                               
-without-debug         Build a production                            
                       version without                               
                       debugging code                                
-without-docs          Skip building of the                          
                       documentation                                 
-without-extra-tools   Skip building                                 
                       utilites in the tools                         
                       directory                                     
-without-geometry      Do not build                                  
                       geometry-related parts                        
-without-libedit       Use system libedit                            
                       instead of bundled                            
                       copy                                          
-without-man           Skip building of the                          
                       man pages                                     
-without-ndb-binlog    Disable ndb binlog                    5.1.6   
-without-ndb-debug     Disable special ndb                           
                       debug features                                
-without-plugin-PLUGIN Exclude PLUGIN                        5.1.11  
-without-query-cache   Do not build query                            
                       cache                                         
-without-readline      Use system readline                           
                       instead of bundled                            
                       copy                                          
-without-row-based-replicationDon't include                         5.1.7   5.1.14
                       row-based replication                         
-without-server        Only build the client                         
-without-uca           Skip building of the                          
                       national Unicode                              
                       collations                                    

Some of the `configure' options available are described here:

   * To compile just the MySQL client libraries and client programs and
     not the server, use the `--without-server' option:

          shell> ./configure --without-server

     If you have no C++ compiler, some client programs such as `mysql'
     cannot be compiled because they require C++.. In this case, you
     can remove the code in `configure' that tests for the C++ compiler
     and then run `./configure' with the `--without-server' option. The
     compile step should still try to build all clients, but you can
     ignore any warnings about files such as `mysql.cc'. (If `make'
     stops, try `make -k' to tell it to continue with the rest of the
     build even if errors occur.)

   * If you want to build the embedded MySQL library (`libmysqld.a'),
     use the `--with-embedded-server' option.

   * If you don't want your log files and database directories located
     under `/usr/local/var', use a `configure' command something like
     one of these:

          shell> ./configure --prefix=/usr/local/mysql
          shell> ./configure --prefix=/usr/local \
                     --localstatedir=/usr/local/mysql/data

     The first command changes the installation prefix so that
     everything is installed under `/usr/local/mysql' rather than the
     default of `/usr/local'. The second command preserves the default
     installation prefix, but overrides the default location for
     database directories (normally `/usr/local/var') and changes it to
     `/usr/local/mysql/data'.

     You can also specify the installation directory and data directory
     locations at server startup time by using the `--basedir' and
     `--datadir' options. These can be given on the command line or in
     an MySQL option file, although it is more common to use an option
     file. See *Note option-files::.

   * If you are using Unix and you want the MySQL socket file location
     to be somewhere other than the default location (normally in the
     directory `/tmp' or `/var/run'), use a `configure' command like
     this:

          shell> ./configure \
                     --with-unix-socket-path=/usr/local/mysql/tmp/mysql.sock

     The socket filename must be an absolute pathname. You can also
     change the location of `mysql.sock' at server startup by using a
     MySQL option file. See *Note problems-with-mysql-sock::.

   * If you want to compile statically linked programs (for example, to
     make a binary distribution, to get better performance, or to work
     around problems with some Red Hat Linux distributions), run
     `configure' like this:

          shell> ./configure --with-client-ldflags=-all-static \
                     --with-mysqld-ldflags=-all-static

   * If you are using `gcc' and don't have `libg++' or `libstdc++'
     installed, you can tell `configure' to use `gcc' as your C++
     compiler:

          shell> CC=gcc CXX=gcc ./configure

     When you use `gcc' as your C++ compiler, it does not attempt to
     link in `libg++' or `libstdc++'. This may be a good thing to do
     even if you have those libraries installed. Some versions of them
     have caused strange problems for MySQL users in the past.

     The following list indicates some compilers and environment
     variable settings that are commonly used with each one.

        * `gcc' 2.7.2:

               CC=gcc CXX=gcc CXXFLAGS="-O3 -felide-constructors"

        * `gcc' 2.95.2:

               CFLAGS="-O3 -mpentiumpro" CXX=gcc CXXFLAGS="-O3 -mpentiumpro \
               -felide-constructors -fno-exceptions -fno-rtti"

        * `pgcc' 2.90.29 or newer:

               CFLAGS="-O3 -mpentiumpro -mstack-align-double" CXX=gcc \
               CXXFLAGS="-O3 -mpentiumpro -mstack-align-double \
               -felide-constructors -fno-exceptions -fno-rtti"

     In most cases, you can get a reasonably optimized MySQL binary by
     using the options from the preceding list and adding the following
     options to the `configure' line:

          --prefix=/usr/local/mysql --enable-assembler \
          --with-mysqld-ldflags=-all-static

     The full `configure' line would, in other words, be something like
     the following for all recent `gcc' versions:

          CFLAGS="-O3 -mpentiumpro" CXX=gcc CXXFLAGS="-O3 -mpentiumpro \
          -felide-constructors -fno-exceptions -fno-rtti" ./configure \
          --prefix=/usr/local/mysql --enable-assembler \
          --with-mysqld-ldflags=-all-static

     The binaries we provide on the MySQL Web site at
     `http://dev.mysql.com/downloads/' are all compiled with full
     optimization and should be perfect for most users. See *Note
     mysql-binaries::. There are some configuration settings you can
     tweak to build an even faster binary, but these are only for
     advanced users. See *Note compile-and-link-options::.

     If the build fails and produces errors about your compiler or
     linker not being able to create the shared library
     `libmysqlclient.so.N' (where N is a version number), you can work
     around this problem by giving the `--disable-shared' option to
     `configure'. In this case, `configure' does not build a shared
     `libmysqlclient.so.N' library.

   * By default, MySQL uses the `latin1' (cp1252 West European)
     character set. To change the default set, use the `--with-charset'
     option:

          shell> ./configure --with-charset=CHARSET

     CHARSET may be one of `binary', `armscii8', `ascii', `big5',
     `cp1250', `cp1251', `cp1256', `cp1257', `cp850', `cp852', `cp866',
     `cp932', `dec8', `eucjpms', `euckr', `gb2312', `gbk', `geostd8',
     `greek', `hebrew', `hp8', `keybcs2', `koi8r', `koi8u', `latin1',
     `latin2', `latin5', `latin7', `macce', `macroman', `sjis', `swe7',
     `tis620', `ucs2', `ujis', `utf8'. See *Note
     charset-configuration::. (Additional character sets might be
     available. Check the output from `./configure --help' for the
     current list.)

     The default collation may also be specified. MySQL uses the
     `latin1_swedish_ci' collation by default.  To change this, use the
     `--with-collation' option:

          shell> ./configure --with-collation=COLLATION

     To change both the character set and the collation, use both the
     `--with-charset' and `--with-collation' options. The collation
     must be a legal collation for the character set. (Use the `SHOW
     COLLATION' statement to determine which collations are available
     for each character set.)

     *Warning*:

     If you change character sets after having created any tables, you
     must run `myisamchk -r -q --set-collation=COLLATION_NAME' _on
     every `MyISAM' table_. Your indexes may be sorted incorrectly
     otherwise. This can happen if you install MySQL, create some
     tables, and then reconfigure MySQL to use a different character
     set and reinstall it.

     With the `configure' option `--with-extra-charsets=LIST', you can
     define which additional character sets should be compiled into the
     server. LIST is one of the following:

        * A list of character set names separated by spaces

        * `complex' to include all character sets that can't be
          dynamically loaded

        * `all' to include all character sets into the binaries

     Clients that want to convert characters between the server and the
     client should use the `SET NAMES' statement. See *Note
     server-session-variables::, and *Note charset-connection::.

   * To configure MySQL with debugging code, use the `--with-debug'
     option:

          shell> ./configure --with-debug

     This causes a safe memory allocator to be included that can find
     some errors and that provides output about what is happening. See
     MySQL Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

     As of MySQL 5.1.12, using `--with-debug' to configure MySQL with
     debugging support enables you to use the
     `--debug="d,parser_debug"' option when you start the server. This
     causes the Bison parser that is used to process SQL statements to
     dump a parser trace to the server's standard error output.
     Typically, this output is written to the error log.

   * If your client programs are using threads, you must compile a
     thread-safe version of the MySQL client library with the
     `--enable-thread-safe-client' configure option. This creates a
     `libmysqlclient_r' library with which you should link your threaded
     applications. See *Note threaded-clients::.

   * Some features require that the server be built with compression
     library support, such as the `COMPRESS()' and `UNCOMPRESS()'
     functions, and compression of the client/server protocol. The
     `--with-zlib-dir=no|bundled|DIR' option provides control for
     compression library support. The value `no' explicitly disables
     compression support. `bundled' causes the `zlib' library bundled
     in the MySQL sources to be used. A DIR pathname specifies where to
     find the compression library sources.

   * It is possible to build MySQL with large table support using the
     `--with-big-tables' option.

     This option causes the variables that store table row counts to be
     declared as `unsigned long long' rather than `unsigned long'. This
     enables tables to hold up to approximately 1.844E+19 ((2^32)^2)
     rows rather than 2^32 (~4.295E+09) rows. Previously it was
     necessary to pass `-DBIG_TABLES' to the compiler manually in order
     to enable this feature.

   * Run `configure' with the `--disable-grant-options' option to cause
     the `--bootstrap', `--skip-grant-tables', and `--init-file'
     options for `mysqld' to be disabled. For Windows, the
     `configure.js' script recognizes the `DISABLE_GRANT_OPTIONS' flag,
     which has the same effect. The capability is available as of MySQL
     5.1.15.

   * See *Note operating-system-specific-notes::, for options that
     pertain to particular operating systems.

   * See *Note secure-using-ssl::, for options that pertain to
     configuring MySQL to support secure (encrypted) connections.

   * Several `configure' options apply to plugin selection and
     building. You can build a plugin as static (compiled into the
     server) or dynamic (built as a dynamic library that must be
     installed using the `INSTALL PLUGIN' statement before it can be
     used). Some plugins might not support static or dynamic build.

     `configure --help' shows the following information pertaining to
     plugins:

        * The plugin-related options

        * The names of all available plugins

        * For each plugin, a description of its purpose, which build
          types it supports (static or dynamic), and which plugin
          groups it is a part of.

     The following `configure' options are used to select or disable
     plugins:

          --with-plugins=PLUGIN[,PLUGIN]...
          --with-plugins=GROUP
          --with-plugin-PLUGIN
          --without-plugin-PLUGIN

     PLUGIN is an individual plugin name such as `csv' or `archive'.

     As shorthand, GROUP is a configuration group name such as `none'
     (select no plugins) or `all' (select all plugins).

     `--with-plugins' can take a list of one or more plugin names
     separated by commas, or a plugin group name. The named plugins are
     configured to be built as static plugins.

     `--with-plugin-PLUGIN' configures the given plugin to be built as
     a static plugin.

     `--without-plugin-PLUGIN' disables the given plugin from being
     built.

     If a plugin is named both with a `--with' and `--without' option,
     the result is undefined.

     For any plugin that is not explicitly selected or disabled, it is
     selected to be built dynamically if it supports dynamic build, and
     not built if it does not support dynamic build. (Thus, in the case
     that no plugin options are given, all plugins that support dynamic
     build are selected to be built as dynamic plugins. Plugins that do
     not support dynamic build are not built.)


File: manual.info,  Node: installing-source-tree,  Next: compilation-problems,  Prev: configure-options,  Up: installing-source

2.9.3 Installing from the Development Source Tree
-------------------------------------------------

*Caution*:

You should read this section only if you are interested in helping us
test our new code. If you just want to get MySQL up and running on your
system, you should use a standard release distribution (either a binary
or source distribution).

To obtain the most recent development source tree, you first need to
download and install Bazaar. You can obtain Bazaar from the Bazaar VCS
Website (http://bazaar-vcs.org). Bazaar is supported by any platform
that supports Python, and is therefore compatible with any Linux, Unix,
Windows or Mac OS X host. Instructions for downloading and installing
Bazaar on the different platforms are available on the Bazaar website.

All MySQL projects are hosted on Launchpad (http://launchpad.net/).
MySQL projects, including MySQL server, MySQL Workbench and others are
available from the Sun/MySQL Engineering (http://launchpad.net/~mysql)
page. For the repositories related only to MySQL server, see the MySQL
Server (http://launchpad.net/mysql-server) page.

To build under Unix/Linux, you must have the following tools installed:

   * GNU `make', available from `http://www.gnu.org/software/make/'.
     Although some platforms come with their own `make'
     implementations, it is highly recommended that you use GNU `make'.
     It may already be available on your system as `gmake'.

   * `autoconf' 2.58 (or newer), available from
     `http://www.gnu.org/software/autoconf/'.

   * `automake' 1.8.1, available from
     `http://www.gnu.org/software/automake/'.

   * `libtool' 1.5, available from
     `http://www.gnu.org/software/libtool/'.

   * `m4', available from `http://www.gnu.org/software/m4/'.

   * `bison', available from `http://www.gnu.org/software/bison/'. You
     should use the latest version of bison where possible.  Version
     1.75 and version 2.1 are known to work. There have been reported
     problems with `bison' 1.875.  If you experience problems, upgrade
     to a later, rather than earlier, version. Versions of `bison' older
     than 1.75 may report this error:

          sql_yacc.yy:#####: fatal error: maximum table size (32767) exceeded

     The maximum table size is not actually exceeded; the error is
     caused by bugs in older versions of `bison'.

To build under Windows you will need a copy of Microsoft Visual C++
2005 Express Edition, Visual Studio .Net 2003 (7.1), or Visual Studio
2005 (8.0) compiler system.

Once you have the necessary tools installed, you first need to create a
local branch of the MySQL source code on your machine:

  1. To obtain a copy of the MySQL source code, you must create a new
     Bazaar branch. If you do not already have a Bazaar repository
     directory set up, you need to initialize a new directory:

          shell> mkdir mysql-server
          shell> bzr init-repo --trees mysql-server

     Once you have an initialized directory, you can `branch' from the
     public MySQL server repositories. To create a branch of a specific
     version:

          shell> cd mysql-server
          shell> bzr branch lp:mysql-server/5.1 mysql-5.1

     The initial download will take some time to complete, depending on
     the speed of your connection. Please be patient. Once you have
     downloaded the first tree, additional trees should take
     significantly less time to download.

     When building from the Bazaar branch, you may want to create a
     copy of your active branch so that you can make configuration and
     other changes without affecting the original branch contents. You
     can achieve this by branching from the original branch:

          shell> bzr branch mysql-5.1 mysql-5.1-build

Once you have the local branch, you can start to build MySQL server
from the source code. On Windows, the build process is different from
Unix/Linux. To continue building MySQL on Windows, see *Note
windows-source-build::.

On Unix/Linux you need to use the `autoconf' system to create the
`configure' script so that you can configure the build environment
before building.

  1. The following example shows the typical commands required to
     configure a source tree. The first `cd' command changes location
     into the top-level directory of the tree; replace `mysql-5.1' with
     the appropriate directory name.

     *Note*:

     For MySQL 5.1.12 and earlier, you must separately configure the
     `INNODB' storage engine.  You can do this by running the following
     command from the main source directory:

          shell> (cd storage/innobase; autoreconf --force --install)

          shell> cd mysql-5.1
          shell> autoreconf --force --install
          shell> ./configure  # Add your favorite options here
          shell> make

     Or you can use `BUILD/autorun.sh' as a shortcut for the following
     sequence of commands:

          shell> aclocal; autoheader
          shell> libtoolize --automake --force
          shell> automake --force --add-missing; autoconf

     The command line that changes directory into the
     `storage/innobase' directory is used to configure the `InnoDB'
     storage engine. You can omit this lines if you do not require
     `InnoDB' support.

     *Note*:

     Beginning with MySQL 5.1, code specific to storage engines has
     been moved under a `storage' directory. For example, `InnoDB' code
     is now found in `storage/innobase' and `NDBCLUSTER' code is in
     `storage/ndb'.

     If you get some strange errors during this stage, verify that you
     have the correct version of the `libtool' installed.

     A collection of our standard configuration scripts is located in
     the `BUILD/' subdirectory. For example, you may find it more
     convenient to use the `BUILD/compile-pentium-debug' script than
     the preceding set of shell commands. To compile on a different
     architecture, modify the script by removing flags that are
     Pentium-specific, or use another script that may be more
     appropriate. These scripts are provided on an `as-is' basis. They
     are not officially maintained and their contents may change from
     release to release.

  2. When the build is done, run `make install'.  Be careful with this
     on a production machine; the command may overwrite your live
     release installation. If you have another installation of MySQL,
     we recommend that you run `./configure' with different values for
     the `--prefix', `--with-tcp-port', and `--unix-socket-path'
     options than those used for your production server.

  3. Play hard with your new installation and try to make the new
     features crash. Start by running `make test'. See *Note
     mysql-test-suite::.

  4. If you have gotten to the `make' stage, but the distribution does
     not compile, please enter the problem into our bugs database using
     the instructions given in *Note bug-reports::. If you have
     installed the latest versions of the required GNU tools, and they
     crash trying to process our configuration files, please report
     that also. However, if you execute `aclocal' and get a `command not
     found' error or a similar problem, do not report it. Instead, make
     sure that all the necessary tools are installed and that your
     `PATH' variable is set correctly so that your shell can find them.

  5. After initially copying the repository with `bzr' to obtain the
     source tree, you should use `pull' option to periodically update
     your local copy. To do this any time after you have set up the
     repository, use this command:

          shell> bzr pull

  6. You can examine the changeset comments for the tree by using the
     `log' option to `bzr':

          shell> bzr log

     You can also browse changesets, comments, and source code online.
     To browse this information for MySQL 5.1, go to
     `http://launchpad.net/mysql-server/'.

     If you see diffs or code that you have a question about, do not
     hesitate to send email to the MySQL `internals' mailing list. See
     *Note mailing-lists::. Also, if you think you have a better idea
     on how to do something, send an email message to the list with a
     patch.


File: manual.info,  Node: compilation-problems,  Next: mit-pthreads,  Prev: installing-source-tree,  Up: installing-source

2.9.4 Dealing with Problems Compiling MySQL
-------------------------------------------

All MySQL programs compile cleanly for us with no warnings on Solaris
or Linux using `gcc'. On other systems, warnings may occur due to
differences in system include files.  See *Note mit-pthreads::, for
warnings that may occur when using MIT-pthreads. For other problems,
check the following list.

The solution to many problems involves reconfiguring. If you do need to
reconfigure, take note of the following:

   * If `configure' is run after it has previously been run, it may use
     information that was gathered during its previous invocation. This
     information is stored in `config.cache'. When `configure' starts
     up, it looks for that file and reads its contents if it exists, on
     the assumption that the information is still correct. That
     assumption is invalid when you reconfigure.

   * Each time you run `configure', you must run `make' again to
     recompile. However, you may want to remove old object files from
     previous builds first because they were compiled using different
     configuration options.

To prevent old configuration information or object files from being
used, run these commands before re-running `configure':

     shell> rm config.cache
     shell> make clean

Alternatively, you can run `make distclean'.

The following list describes some of the problems when compiling MySQL
that have been found to occur most often:

   * If you get errors such as the ones shown here when compiling
     `sql_yacc.cc', you probably have run out of memory or swap space:

          Internal compiler error: program cc1plus got fatal signal 11
          Out of virtual memory
          Virtual memory exhausted

     The problem is that `gcc' requires a huge amount of memory to
     compile `sql_yacc.cc' with inline functions. Try running
     `configure' with the `--with-low-memory' option:

          shell> ./configure --with-low-memory

     This option causes `-fno-inline' to be added to the compile line
     if you are using `gcc' and `-O0' if you are using something else.
     You should try the `--with-low-memory' option even if you have so
     much memory and swap space that you think you can't possibly have
     run out. This problem has been observed to occur even on systems
     with generous hardware configurations, and the `--with-low-memory'
     option usually fixes it.

   * By default, `configure' picks `c++' as the compiler name and GNU
     `c++' links with `-lg++'. If you are using `gcc', that behavior can
     cause problems during configuration such as this:

          configure: error: installation or configuration problem:
          C++ compiler cannot create executables.

     You might also observe problems during compilation related to
     `g++', `libg++', or `libstdc++'.

     One cause of these problems is that you may not have `g++', or you
     may have `g++' but not `libg++', or `libstdc++'. Take a look at the
     `config.log' file. It should contain the exact reason why your C++
     compiler didn't work. To work around these problems, you can use
     `gcc' as your C++ compiler. Try setting the environment variable
     `CXX' to `"gcc -O3"'. For example:

          shell> CXX="gcc -O3" ./configure

     This works because `gcc' compiles C++ source files as well as
     `g++' does, but does not link in `libg++' or `libstdc++' by
     default.

     Another way to fix these problems is to install `g++', `libg++',
     and `libstdc++'. However, we recommend that you not use `libg++' or
     `libstdc++' with MySQL because this only increases the binary size
     of `mysqld' without providing any benefits. Some versions of these
     libraries have also caused strange problems for MySQL users in the
     past.

   * If your compile fails with errors such as any of the following,
     you must upgrade your version of `make' to GNU `make':

          making all in mit-pthreads
          make: Fatal error in reader: Makefile, line 18:
          Badly formed macro assignment

     Or:

          make: file `Makefile' line 18: Must be a separator (:

     Or:

          pthread.h: No such file or directory

     Solaris and FreeBSD are known to have troublesome `make' programs.

     GNU `make' 3.75 is known to work.

   * If you want to define flags to be used by your C or C++ compilers,
     do so by adding the flags to the `CFLAGS' and `CXXFLAGS'
     environment variables. You can also specify the compiler names
     this way using `CC' and `CXX'. For example:

          shell> CC=gcc
          shell> CFLAGS=-O3
          shell> CXX=gcc
          shell> CXXFLAGS=-O3
          shell> export CC CFLAGS CXX CXXFLAGS

     See *Note mysql-binaries::, for a list of flag definitions that
     have been found to be useful on various systems.

   * If you get errors such as those shown here when compiling
     `mysqld', `configure' did not correctly detect the type of the
     last argument to `accept()', `getsockname()', or `getpeername()':

          cxx: Error: mysqld.cc, line 645: In this statement, the referenced
               type of the pointer value ''length'' is ''unsigned long'',
               which is not compatible with ''int''.
          new_sock = accept(sock, (struct sockaddr *)&cAddr, &length);

     To fix this, edit the `config.h' file (which is generated by
     `configure'). Look for these lines:

          /* Define as the base type of the last arg to accept */
          #define SOCKET_SIZE_TYPE XXX

     Change `XXX' to `size_t' or `int', depending on your operating
     system. (You must do this each time you run `configure' because
     `configure' regenerates `config.h'.)

   * The `sql_yacc.cc' file is generated from `sql_yacc.yy'. Normally,
     the build process does not need to create `sql_yacc.cc' because
     MySQL comes with a pre-generated copy. However, if you do need to
     re-create it, you might encounter this error:

          "sql_yacc.yy", line XXX fatal: default action causes potential...

     This is a sign that your version of `yacc' is deficient. You
     probably need to install `bison' (the GNU version of `yacc') and
     use that instead.

   * On Debian Linux 3.0, you need to install `gawk' instead of the
     default `mawk'.

   * If you need to debug `mysqld' or a MySQL client, run `configure'
     with the `--with-debug' option, and then recompile and link your
     clients with the new client library. See MySQL Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

   * If you get a compilation error on Linux (for example, SuSE Linux
     8.1 or Red Hat Linux 7.3) similar to the following one, you
     probably do not have `g++' installed:

          libmysql.c:1329: warning: passing arg 5 of `gethostbyname_r' from
          incompatible pointer type
          libmysql.c:1329: too few arguments to function `gethostbyname_r'
          libmysql.c:1329: warning: assignment makes pointer from integer
          without a cast
          make[2]: *** [libmysql.lo] Error 1

     By default, the `configure' script attempts to determine the
     correct number of arguments by using `g++' (the GNU C++ compiler).
     This test yields incorrect results if `g++' is not installed.
     There are two ways to work around this problem:

        * Make sure that the GNU C++ `g++' is installed. On some Linux
          distributions, the required package is called `gpp'; on
          others, it is named `gcc-c++'.

        * Use `gcc' as your C++ compiler by setting the `CXX'
          environment variable to `gcc':

               export CXX="gcc"

     You must run `configure' again after making either of those
     changes.


File: manual.info,  Node: mit-pthreads,  Next: windows-source-build,  Prev: compilation-problems,  Up: installing-source

2.9.5 MIT-pthreads Notes
------------------------

This section describes some of the issues involved in using
MIT-pthreads.

On Linux, you should _not_ use MIT-pthreads.  Use the installed
LinuxThreads implementation instead. See *Note linux::.

If your system does not provide native thread support, you should build
MySQL using the MIT-pthreads package. This includes older FreeBSD
systems, SunOS 4.x, Solaris 2.4 and earlier, and some others. See *Note
which-os::.

MIT-pthreads is not part of the MySQL 5.1 source distribution. If you
require this package, you need to download it separately from
`http://dev.mysql.com/Downloads/Contrib/pthreads-1_60_beta6-mysql.tar.gz'

After downloading, extract this source archive into the top level of
the MySQL source directory. It creates a new subdirectory named
`mit-pthreads'.

   * On most systems, you can force MIT-pthreads to be used by running
     `configure' with the `--with-mit-threads' option:

          shell> ./configure --with-mit-threads

     Building in a non-source directory is not supported when using
     MIT-pthreads because we want to minimize our changes to this code.

   * The checks that determine whether to use MIT-pthreads occur only
     during the part of the configuration process that deals with the
     server code. If you have configured the distribution using
     `--without-server' to build only the client code, clients do not
     know whether MIT-pthreads is being used and use Unix socket file
     connections by default. Because Unix socket files do not work
     under MIT-pthreads on some platforms, this means you need to use
     `-h' or `--host' with a value other than `localhost' when you run
     client programs.

   * When MySQL is compiled using MIT-pthreads, system locking is
     disabled by default for performance reasons. You can tell the
     server to use system locking with the `--external-locking' option.
     This is needed only if you want to be able to run two MySQL
     servers against the same data files, but that is not recommended,
     anyway.

   * Sometimes the pthread `bind()' command fails to bind to a socket
     without any error message (at least on Solaris). The result is
     that all connections to the server fail. For example:

          shell> mysqladmin version
          mysqladmin: connect to server at '' failed;
          error: 'Can't connect to mysql server on localhost (146)'

     The solution to this problem is to kill the `mysqld' server and
     restart it. This has happened to us only when we have forcibly
     stopped the server and restarted it immediately.

   * With MIT-pthreads, the `sleep()' system call isn't interruptible
     with `SIGINT' (break). This is noticeable only when you run
     `mysqladmin --sleep'. You must wait for the `sleep()' call to
     terminate before the interrupt is served and the process stops.

   * When linking, you might receive warning messages like these (at
     least on Solaris); they can be ignored:

          ld: warning: symbol `_iob' has differing sizes:
              (file /my/local/pthreads/lib/libpthread.a(findfp.o) value=0x4;
          file /usr/lib/libc.so value=0x140);
              /my/local/pthreads/lib/libpthread.a(findfp.o) definition taken
          ld: warning: symbol `__iob' has differing sizes:
              (file /my/local/pthreads/lib/libpthread.a(findfp.o) value=0x4;
          file /usr/lib/libc.so value=0x140);
              /my/local/pthreads/lib/libpthread.a(findfp.o) definition taken

   * Some other warnings also can be ignored:

          implicit declaration of function `int strtoll(...)'
          implicit declaration of function `int strtoul(...)'

   * We have not been able to make `readline' work with MIT-pthreads.
     (This is not necessary, but may be of interest to some.)


File: manual.info,  Node: windows-source-build,  Next: windows-client-compiling,  Prev: mit-pthreads,  Up: installing-source

2.9.6 Installing MySQL from Source on Windows
---------------------------------------------

* Menu:

* windows-source-build-cmake::   Building MySQL from Source Using CMake and Visual Studio

These instructions describe how to build binaries from source for MySQL
5.1 on Windows. Instructions are provided for building binaries from a
standard source distribution or from the Bazaar tree that contains the
latest development source.

*Note*:

The instructions here are strictly for users who want to test MySQL on
Microsoft Windows from the latest source distribution or from the
Bazaar tree. For production use, MySQL AB does not advise using a MySQL
server built by yourself from source.  Normally, it is best to use
precompiled binary distributions of MySQL that are built specifically
for optimal performance on Windows by MySQL AB. Instructions for
installing binary distributions are available in *Note
windows-installation::.

To build MySQL on Windows from source, you must satisfy the following
system, compiler, and resource requirements:

   * Windows 2000, Windows XP, or newer version.

     Windows Vista is supported when using Visual Studio 2005 provided
     you have installed the following updates:

        * Microsoft Visual Studio 2005 Professional Edition - ENU
          Service Pack 1 (KB926601)
          (http://support.microsoft.com/?kbid=926601)

        * Security Update for Microsoft Visual Studio 2005 Professional
          Edition - ENU (KB937061)
          (http://support.microsoft.com/?kbid=937061)

        * Update for Microsoft Visual Studio 2005 Professional Edition
          - ENU (KB932232) (http://support.microsoft.com/?kbid=932232)

   * CMake, which can be downloaded from `http://www.cmake.org'. After
     installing, modify your path to include the `cmake' binary.

   * Microsoft Visual C++ 2005 Express Edition, Visual Studio .Net 2003
     (7.1), or Visual Studio 2005 (8.0) compiler system.

   * If you are using Visual C++ 2005 Express Edition, you must also
     install an appropriate Platform SDK. More information and links to
     downloads for various Windows platforms is available from
     `http://msdn.microsoft.com/platformsdk/'.

   * If you are compiling from a Bazaar tree or making changes to the
     parser, you need `bison' for Windows, which can be downloaded from
     `http://gnuwin32.sourceforge.net/packages/bison.htm'.  Download
     the package labeled `Complete package, excluding sources'. After
     installing the package, modify your path to include the `bison'
     binary and ensure that this binary is accessible from Visual
     Studio.

   * Cygwin might be necessary if you want to run the test script or
     package the compiled binaries and support files into a Zip
     archive. (Cygwin is needed only to test or package the
     distribution, not to build it.) Cygwin is available from
     `http://cygwin.com'.

   * 3GB to 5GB of disk space.

The exact system requirements can be found here:
`http://msdn.microsoft.com/vstudio/Previous/2003/sysreqs/default.aspx'
and `http://msdn.microsoft.com/vstudio/products/sysreqs/default.aspx'

You also need a MySQL source distribution for Windows, which can be
obtained two ways:

   * Obtain a source distribution packaged by MySQL AB. These are
     available from `http://dev.mysql.com/downloads/'.

   * Package a source distribution yourself from the latest Bazaar
     developer source tree. For instructions on pulling the latest
     source files, see *Note installing-source-tree::.

If you find something not working as expected, or you have suggestions
about ways to improve the current build process on Windows, please send
a message to the `win32' mailing list. See *Note mailing-lists::.


File: manual.info,  Node: windows-source-build-cmake,  Prev: windows-source-build,  Up: windows-source-build

2.9.6.1 Building MySQL from Source Using CMake and Visual Studio
................................................................

You can build MySQL on Windows by using a combination of `cmake' and
Microsoft Visual Studio .NET 2003 (7.1), Micrsofot Visual Studio 2005
(8.0) or Microsoft Visual C++ 2005 Express Edition. You must have the
appropriate Microsoft Platform SDK installed.

*Note*:

To compile from the source code on Windows you must use the standard
source distribution (for example, `mysql-5.0.45.tar.gz').  You build
from the same distribution as used to build MySQL on Unix, Linux and
other platforms. Do _not_ use the Windows Source distributions as they
do not contain the necessary configuration script and other files.

Follow this procedure to build MySQL:

  1. If you are installing from a packaged source distribution, create
     a work directory (for example, `C:\workdir'), and unpack the source
     distribution there using `WinZip' or another Windows tool that can
     read `.zip' files. This directory is the work directory in the
     following instructions.

  2. If you are installing from a Bazaar tree, the root directory of
     that tree is the work directory in the following instructions.

  3. Using a command shell, navigate to the work directory and run the
     following command:

          C:\workdir>win\configure OPTIONS

     These options are available:

        * `WITH_INNOBASE_STORAGE_ENGINE': Enable the `InnoDB' storage
          engine.

        * `WITH_PARTITION_STORAGE_ENGINE': Enable user-defined
          partitioning.

        * `WITH_ARCHIVE_STORAGE_ENGINE': Enable the `ARCHIVE' storage
          engine.

        * `WITH_BLACKHOLE_STORAGE_ENGINE': Enable the `BLACKHOLE'
          storage engine.

        * `WITH_EXAMPLE_STORAGE_ENGINE': Enable the `EXAMPLE' storage
          engine.

        * `WITH_FEDERATED_STORAGE_ENGINE': Enable the `FEDERATED'
          storage engine.

        * `__NT__': Enable support for named pipes.

        * `MYSQL_SERVER_SUFFIX=SUFFIX': Server suffix, default none.

        * `COMPILATION_COMMENT=COMMENT': Server comment, default
          "Source distribution".

        * `MYSQL_TCP_PORT=PORT': Server port, default 3306.

        * `DISABLE_GRANT_OPTIONS': Disables the `--bootstrap',
          `--skip-grant-tables', and `--init-file' options for
          `mysqld'. This option is available as of MySQL 5.1.15.

     For example (type the command on one line):

          C:\workdir>win\configure WITH_INNOBASE_STORAGE_ENGINE
                       WITH_PARTITION_STORAGE_ENGINE MYSQL_SERVER_SUFFIX=-pro

  4. From the work directory, execute the `win\build-vs8.bat' or
     `win\build-vs71.bat' file, depending on the version of Visual
     Studio you have installed. The script invokes CMake, which
     generates the `mysql.sln' solution file.

     You can also use `win\build-vs8_x64.bat' to build the 64-bit
     version of MySQL. However, you cannot build the 64-bit version
     with Visual Studio Express Edition. You must use Visual Studio
     2005 (8.0) or higher.

  5. From the work directory, open the generated `mysql.sln' file with
     Visual Studio and select the proper configuration using the
     `Configuration' menu. The menu provides `Debug', `Release',
     `RelwithDebInfo', `MinRelInfo' options. Then select `Solution' >
     `Build' to build the solution.

     Remember the configuration that you use in this step. It is
     important later when you run the test script because that script
     needs to know which configuration you used.

  6. Test the server. The server built using the preceding instructions
     expects that the MySQL base directory and data directory are
     `C:\mysql' and `C:\mysql\data' by default. If you want to test
     your server using the source tree root directory and its data
     directory as the base directory and data directory, you need to
     tell the server their pathnames.  You can either do this on the
     command line with the `--basedir' and `--datadir' options, or by
     placing appropriate options in an option file. (See *Note
     option-files::.) If you have an existing data directory elsewhere
     that you want to use, you can specify its pathname instead.

     When the server is running in standalone fashion or as a service
     based on your configuration, try to connect to it from the `mysql'
     interactive command-line utility.

     You can also run the standard test script, `mysql-test-run.pl'.
     This script is written in Perl, so you'll need either Cygwin or
     ActiveState Perl to run it. You may also need to install the
     modules required by the script. To run the test script, change
     location into the `mysql-test' directory under the work directory,
     set the `MTR_VS_CONFIG' environment variable to the configuration
     you selected earlier (or use the `--vs-config' option), and invoke
     `mysql-test-run.pl'.  For example (using Cygwin and the `bash'
     shell):

          shell> `cd mysql-test'
          shell> `export MTS_VS_CONFIG=debug'
          shell> `./mysqltest-run.pl --force --timer'
          shell> `./mysqltest-run.pl --force --timer --ps-protocol'

When you are satisfied that the programs you have built are working
correctly, stop the server. Now you can install the distribution. One
way to do this is to use the `make_win_bin_dist' script in the
`scripts' directory of the MySQL source distribution (see *Note
make-win-bin-dist::). This is a shell script, so you must have Cygwin
installed if you want to use it. It creates a Zip archive of the built
executables and support files that you can unpack in the location at
which you want to install MySQL.

It is also possible to install MySQL by copying directories and files
directly:

  1. Create the directories where you want to install MySQL.  For
     example, to install into `C:\mysql', use these commands:

          C:\> mkdir C:\mysql
          C:\> mkdir C:\mysql\bin
          C:\> mkdir C:\mysql\data
          C:\> mkdir C:\mysql\share
          C:\> mkdir C:\mysql\scripts

     If you want to compile other clients and link them to MySQL, you
     should also create several additional directories:

          C:\> mkdir C:\mysql\include
          C:\> mkdir C:\mysql\lib
          C:\> mkdir C:\mysql\lib\debug
          C:\> mkdir C:\mysql\lib\opt

     If you want to benchmark MySQL, create this directory:

          C:\> mkdir C:\mysql\sql-bench

     Benchmarking requires Perl support. See *Note perl-support::.

  2. From the work directory, copy into the `C:\mysql' directory the
     following directories:

          C:\> cd \workdir
          C:\workdir> copy client_release\*.exe C:\mysql\bin
          C:\workdir> copy client_debug\mysqld.exe C:\mysql\bin\mysqld-debug.exe
          C:\workdir> xcopy scripts\*.* C:\mysql\scripts /E
          C:\workdir> xcopy share\*.* C:\mysql\share /E

     If you want to compile other clients and link them to MySQL, you
     should also copy several libraries and header files:

          C:\workdir> copy lib_debug\mysqlclient.lib C:\mysql\lib\debug
          C:\workdir> copy lib_debug\libmysql.* C:\mysql\lib\debug
          C:\workdir> copy lib_debug\zlib.* C:\mysql\lib\debug
          C:\workdir> copy lib_release\mysqlclient.lib C:\mysql\lib\opt
          C:\workdir> copy lib_release\libmysql.* C:\mysql\lib\opt
          C:\workdir> copy lib_release\zlib.* C:\mysql\lib\opt
          C:\workdir> copy include\*.h C:\mysql\include
          C:\workdir> copy libmysql\libmysql.def C:\mysql\include

     If you want to benchmark MySQL, you should also do this:

          C:\workdir> xcopy sql-bench\*.* C:\mysql\bench /E

After installation, set up and start the server in the same way as for
binary Windows distributions. See *Note windows-installation::.


File: manual.info,  Node: windows-client-compiling,  Prev: windows-source-build,  Up: installing-source

2.9.7 Compiling MySQL Clients on Windows
----------------------------------------

In your source files, you should include `my_global.h' before `mysql.h':

     #include <my_global.h>
     #include <mysql.h>

`my_global.h' includes any other files needed for Windows compatibility
(such as `windows.h') if you compile your program on Windows.

You can either link your code with the dynamic `libmysql.lib' library,
which is just a wrapper to load in `libmysql.dll' on demand, or link
with the static `mysqlclient.lib' library.

The MySQL client libraries are compiled as threaded libraries, so you
should also compile your code to be multi-threaded.


File: manual.info,  Node: post-installation,  Next: upgrade,  Prev: installing-source,  Up: installing

2.10 Post-Installation Setup and Testing
========================================

* Menu:

* windows-post-installation::    Windows Post-Installation Procedures
* unix-post-installation::       Unix Post-Installation Procedures
* default-privileges::           Securing the Initial MySQL Accounts

After installing MySQL, there are some issues that you should address.
For example, on Unix, you should initialize the data directory and
create the MySQL grant tables. On all platforms, an important security
concern is that the initial accounts in the grant tables have no
passwords. You should assign passwords to prevent unauthorized access
to the MySQL server. Optionally, you can create time zone tables to
enable recognition of named time zones.

The following sections include post-installation procedures that are
specific to Windows systems and to Unix systems. Another section, *Note
starting-server::, applies to all platforms; it describes what to do if
you have trouble getting the server to start. *Note
default-privileges::, also applies to all platforms. You should follow
its instructions to make sure that you have properly protected your
MySQL accounts by assigning passwords to them.

When you are ready to create additional user accounts, you can find
information on the MySQL access control system and account management
in *Note privilege-system::, and *Note user-account-management::.


File: manual.info,  Node: windows-post-installation,  Next: unix-post-installation,  Prev: post-installation,  Up: post-installation

2.10.1 Windows Post-Installation Procedures
-------------------------------------------

On Windows, the data directory and the grant tables do not have to be
created. MySQL Windows distributions include the grant tables with a
set of preinitialized accounts in the `mysql' database under the data
directory. It is unnecessary to run the `mysql_install_db' script that
is used on Unix. Regarding passwords, if you installed MySQL using the
Windows Installation Wizard, you may have already assigned passwords to
the accounts. (See *Note windows-install-wizard::.) Otherwise, use the
password-assignment procedure given in *Note default-privileges::.

Before setting up passwords, you might want to try running some client
programs to make sure that you can connect to the server and that it is
operating properly. Make sure that the server is running (see *Note
windows-server-first-start::), and then issue the following commands to
verify that you can retrieve information from the server. The output
should be similar to what is shown here:

     C:\> C:\mysql\bin\mysqlshow
     +--------------------+
     |     Databases      |
     +--------------------+
     | information_schema |
     | mysql              |
     | test               |
     +--------------------+

     C:\> C:\mysql\bin\mysqlshow mysql
     Database: mysql
     +---------------------------+
     |          Tables           |
     +---------------------------+
     | columns_priv              |
     | db                        |
     | event                     |
     | func                      |
     | general_log               |
     | help_category             |
     | help_keyword              |
     | help_relation             |
     | help_topic                |
     | host                      |
     | plugin                    |
     | proc                      |
     | procs_priv                |
     | servers                   |
     | slow_log                  |
     | tables_priv               |
     | time_zone                 |
     | time_zone_leap_second     |
     | time_zone_name            |
     | time_zone_transition      |
     | time_zone_transition_type |
     | user                      |
     +---------------------------+

     C:\> C:\mysql\bin\mysql -e "SELECT Host,Db,User FROM db" mysql
     +------+-------+------+
     | host | db    | user |
     +------+-------+------+
     | %    | test% |      |
     +------+-------+------+

You may need to specify a different directory from the one shown; if
you used the Windows Installation Wizard, then the default directory is
`C:\Program Files\MySQL\MySQL Server 5.1', and the `mysql' and
`mysqlshow' client programs are in `C:\Program Files\MySQL\MySQL Server
5.1\bin'. See *Note windows-install-wizard::, for more information.

If you have already secured the initial MySQL accounts, you may need to
use the `-u' and `-p' options to supply a username and password to the
`mysqlshow' and `mysql' client programs; otherwise the programs may
fail with an error, or you may not be able to view all databases. For
example, if you have assigned the password `secretpass' to the MySQL
`root' account, then you can invoke `mysqlshow'and `mysql' as shown
here:

     C:\> C:\mysql\bin\mysqlshow -uroot -psecretpass
     +--------------------+
     |     Databases      |
     +--------------------+
     | information_schema |
     | mysql              |
     | test               |
     +--------------------+

     C:\> C:\mysql\bin\mysqlshow -uroot -psecretpass mysql
     Database: mysql
     +---------------------------+
     |          Tables           |
     +---------------------------+
     | columns_priv              |
     | db                        |
     | event                     |
     | func                      |
     | general_log               |
     | help_category             |
     | help_keyword              |
     | help_relation             |
     | help_topic                |
     | host                      |
     | plugin                    |
     | proc                      |
     | procs_priv                |
     | servers                   |
     | slow_log                  |
     | tables_priv               |
     | time_zone                 |
     | time_zone_leap_second     |
     | time_zone_name            |
     | time_zone_transition      |
     | time_zone_transition_type |
     | user                      |
     +---------------------------+

     C:\> C:\mysql\bin\mysql -uroot -psecretpass -e "SELECT Host,Db,User FROM db" mysql
     +------+-------+------+
     | host | db    | user |
     +------+-------+------+
     | %    | test% |      |
     +------+-------+------+

For more information about these programs, see *Note mysqlshow::, and
*Note mysql::.

If you are running a version of Windows that supports services and you
want the MySQL server to run automatically when Windows starts, see
*Note windows-start-service::.


File: manual.info,  Node: unix-post-installation,  Next: default-privileges,  Prev: windows-post-installation,  Up: post-installation

2.10.2 Unix Post-Installation Procedures
----------------------------------------

* Menu:

* mysql-install-db-problems::    Problems Running `mysql_install_db'
* automatic-start::              Starting and Stopping MySQL Automatically
* starting-server::              Starting and Troubleshooting the MySQL Server

After installing MySQL on Unix, you need to initialize the grant
tables, start the server, and make sure that the server works
satisfactorily. You may also wish to arrange for the server to be
started and stopped automatically when your system starts and stops.
You should also assign passwords to the accounts in the grant tables.

On Unix, the grant tables are set up by the `mysql_install_db' program.
For some installation methods, this program is run for you
automatically:

   * If you install MySQL on Linux using RPM distributions, the server
     RPM runs `mysql_install_db'.

   * If you install MySQL on Mac OS X using a PKG distribution, the
     installer runs `mysql_install_db'.

Otherwise, you'll need to run `mysql_install_db' yourself.

The following procedure describes how to initialize the grant tables
(if that has not previously been done) and then start the server. It
also suggests some commands that you can use to test whether the server
is accessible and working properly. For information about starting and
stopping the server automatically, see *Note automatic-start::.

After you complete the procedure and have the server running, you
should assign passwords to the accounts created by `mysql_install_db'.
Instructions for doing so are given in *Note default-privileges::.

In the examples shown here, the server runs under the user ID of the
`mysql' login account. This assumes that such an account exists. Either
create the account if it does not exist, or substitute the name of a
different existing login account that you plan to use for running the
server.

  1. Change location into the top-level directory of your MySQL
     installation, represented here by BASEDIR:

          shell> cd BASEDIR

     BASEDIR is likely to be something like `/usr/local/mysql' or
     `/usr/local'. The following steps assume that you are located in
     this directory.

  2. If necessary, run the `mysql_install_db' program to set up the
     initial MySQL grant tables containing the privileges that
     determine how users are allowed to connect to the server. You'll
     need to do this if you used a distribution type for which the
     installation procedure doesn't run the program for you.

     Typically, `mysql_install_db' needs to be run only the first time
     you install MySQL, so you can skip this step if you are upgrading
     an existing installation, However, `mysql_install_db' does not
     overwrite any existing privilege tables, so it should be safe to
     run in any circumstances.

     To initialize the grant tables, use one of the following commands,
     depending on whether `mysql_install_db' is located in the `bin' or
     `scripts' directory:

          shell> bin/mysql_install_db --user=mysql
          shell> scripts/mysql_install_db --user=mysql

     The `mysql_install_db' script creates the server's data directory.
     Under the data directory, it creates directories for the `mysql'
     database that holds all database privileges and the `test'
     database that you can use to test MySQL. The script also creates
     privilege table entries for `root' and anonymous-user accounts. The
     accounts have no passwords initially. A description of their
     initial privileges is given in *Note default-privileges::.
     Briefly, these privileges allow the MySQL `root' user to do
     anything, and allow anybody to create or use databases with a name
     of `test' or starting with `test_'.

     It is important to make sure that the database directories and
     files are owned by the `mysql' login account so that the server
     has read and write access to them when you run it later. To ensure
     this, the `--user' option should be used as shown if you run
     `mysql_install_db' as `root'. Otherwise, you should execute the
     script while logged in as `mysql', in which case you can omit the
     `--user' option from the command.

     `mysql_install_db' creates several tables in the `mysql' database,
     including `user', `db', `host', `tables_priv', `columns_priv',
     `func', and others. See *Note privilege-system::, for a complete
     listing and description of these tables.

     If you don't want to have the `test' database, you can remove it
     with `mysqladmin -u root drop test' after starting the server.

     If you have trouble with `mysql_install_db' at this point, see
     *Note mysql-install-db-problems::.

  3. Start the MySQL server:

          shell> bin/mysqld_safe --user=mysql &

     It is important that the MySQL server be run using an unprivileged
     (non-`root') login account. To ensure this, the `--user' option
     should be used as shown if you run `mysqld_safe' as system `root'.
     Otherwise, you should execute the script while logged in to the
     system as `mysql', in which case you can omit the `--user' option
     from the command.

     Further instructions for running MySQL as an unprivileged user are
     given in *Note changing-mysql-user::.

     If you neglected to create the grant tables before proceeding to
     this step, the following message appears in the error log file
     when you start the server:

          mysqld: Can't find file: 'host.frm'

     If you have other problems starting the server, see *Note
     starting-server::.

  4. Use `mysqladmin' to verify that the server is running. The
     following commands provide simple tests to check whether the
     server is up and responding to connections:

          shell> bin/mysqladmin version
          shell> bin/mysqladmin variables

     The output from `mysqladmin version' varies slightly depending on
     your platform and version of MySQL, but should be similar to that
     shown here:

          shell> bin/mysqladmin version
          mysqladmin  Ver 14.12 Distrib 5.1.28, for pc-linux-gnu on i686
          Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
          This software comes with ABSOLUTELY NO WARRANTY. This is free software,
          and you are welcome to modify and redistribute it under the GPL license

          Server version          5.1.28
          Protocol version        10
          Connection              Localhost via UNIX socket
          UNIX socket             /var/lib/mysql/mysql.sock
          Uptime:                 14 days 5 hours 5 min 21 sec

          Threads: 1  Questions: 366  Slow queries: 0
          Opens: 0  Flush tables: 1  Open tables: 19
          Queries per second avg: 0.000

     To see what else you can do with `mysqladmin', invoke it with the
     `--help' option.

  5. Verify that you can shut down the server:

          shell> bin/mysqladmin -u root shutdown

  6. Verify that you can start the server again. Do this by using
     `mysqld_safe' or by invoking `mysqld' directly. For example:

          shell> bin/mysqld_safe --user=mysql --log &

     If `mysqld_safe' fails, see *Note starting-server::.

  7. Run some simple tests to verify that you can retrieve information
     from the server. The output should be similar to what is shown
     here:

          shell> bin/mysqlshow
          +-----------+
          | Databases |
          +-----------+
          | mysql     |
          | test      |
          +-----------+

          shell> bin/mysqlshow mysql
          Database: mysql
          +---------------------------+
          |          Tables           |
          +---------------------------+
          | columns_priv              |
          | db                        |
          | func                      |
          | help_category             |
          | help_keyword              |
          | help_relation             |
          | help_topic                |
          | host                      |
          | proc                      |
          | procs_priv                |
          | tables_priv               |
          | time_zone                 |
          | time_zone_leap_second     |
          | time_zone_name            |
          | time_zone_transition      |
          | time_zone_transition_type |
          | user                      |
          +---------------------------+

          shell> bin/mysql -e "SELECT Host,Db,User FROM db" mysql
          +------+--------+------+
          | host | db     | user |
          +------+--------+------+
          | %    | test   |      |
          | %    | test_% |      |
          +------+--------+------+

  8. There is a benchmark suite in the `sql-bench' directory (under the
     MySQL installation directory) that you can use to compare how
     MySQL performs on different platforms. The benchmark suite is
     written in Perl. It requires the Perl DBI module that provides a
     database-independent interface to the various databases, and some
     other additional Perl modules:

          DBI
          DBD::mysql
          Data::Dumper
          Data::ShowTable

     These modules can be obtained from CPAN (`http://www.cpan.org/').
     See also *Note perl-installation::.

     The `sql-bench/Results' directory contains the results from many
     runs against different databases and platforms. To run all tests,
     execute these commands:

          shell> cd sql-bench
          shell> perl run-all-tests

     If you don't have the `sql-bench' directory, you probably
     installed MySQL using RPM files other than the source RPM. (The
     source RPM includes the `sql-bench' benchmark directory.) In this
     case, you must first install the benchmark suite before you can
     use it. There are separate benchmark RPM files named
     `mysql-bench-VERSION.i386.rpm' that contain benchmark code and
     data.

     If you have a source distribution, there are also tests in its
     `tests' subdirectory that you can run. For example, to run
     `auto_increment.tst', execute this command from the top-level
     directory of your source distribution:

          shell> mysql -vvf test < ./tests/auto_increment.tst

     The expected result of the test can be found in the
     `./tests/auto_increment.res' file.

  9. At this point, you should have the server running. However, none
     of the initial MySQL accounts have a password, so you should
     assign passwords using the instructions found in *Note
     default-privileges::.

The MySQL 5.1 installation procedure creates time zone tables in the
`mysql' database. However, you must populate the tables manually using
the instructions in *Note time-zone-support::.


File: manual.info,  Node: mysql-install-db-problems,  Next: automatic-start,  Prev: unix-post-installation,  Up: unix-post-installation

2.10.2.1 Problems Running `mysql_install_db'
............................................

The purpose of the `mysql_install_db' script is to generate new MySQL
privilege tables. It does not overwrite existing MySQL privilege
tables, and it does not affect any other data.

If you want to re-create your privilege tables, first stop the `mysqld'
server if it's running. Then rename the `mysql' directory under the data
directory to save it, and then run `mysql_install_db'. Suppose that
your current directory is the MySQL installation directory and that
`mysql_install_db' is located in the `bin' directory and the data
directory is named `data'. To rename the `mysql' database and re-run
`mysql_install_db', use these commands.

     shell> mv data/mysql data/mysql.old
     shell> bin/mysql_install_db --user=mysql

When you run `mysql_install_db', you might encounter the following
problems:

   * *`mysql_install_db' fails to install the grant tables*

     You may find that `mysql_install_db' fails to install the grant
     tables and terminates after displaying the following messages:

          Starting mysqld daemon with databases from XXXXXX
          mysqld ended

     In this case, you should examine the error log file very
     carefully. The log should be located in the directory `XXXXXX'
     named by the error message and should indicate why `mysqld' didn't
     start. If you do not understand what happened, include the log
     when you post a bug report. See *Note bug-reports::.

   * *There is a `mysqld' process running*

     This indicates that the server is running, in which case the grant
     tables have probably been created already. If so, there is no need
     to run `mysql_install_db' at all because it needs to be run only
     once (when you install MySQL the first time).

   * *Installing a second `mysqld' server does not work when one server
     is running*

     This can happen when you have an existing MySQL installation, but
     want to put a new installation in a different location. For
     example, you might have a production installation, but you want to
     create a second installation for testing purposes. Generally the
     problem that occurs when you try to run a second server is that it
     tries to use a network interface that is in use by the first
     server. In this case, you should see one of the following error
     messages:

          Can't start server: Bind on TCP/IP port:
          Address already in use
          Can't start server: Bind on unix socket...

     For instructions on setting up multiple servers, see *Note
     multiple-servers::.

   * *You do not have write access to the `/tmp' directory*

     If you do not have write access to create temporary files or a
     Unix socket file in the default location (the `/tmp' directory),
     an error occurs when you run `mysql_install_db' or the `mysqld'
     server.

     You can specify different locations for the temporary directory
     and Unix socket file by executing these commands prior to starting
     `mysql_install_db' or `mysqld', where SOME_TMP_DIR is the full
     pathname to some directory for which you have write permission:

          shell> TMPDIR=/SOME_TMP_DIR/
          shell> MYSQL_UNIX_PORT=/SOME_TMP_DIR/mysql.sock
          shell> export TMPDIR MYSQL_UNIX_PORT

     Then you should be able to run `mysql_install_db' and start the
     server with these commands:

          shell> bin/mysql_install_db --user=mysql
          shell> bin/mysqld_safe --user=mysql &

     If `mysql_install_db' is located in the `scripts' directory,
     modify the first command to `scripts/mysql_install_db'.

     See *Note problems-with-mysql-sock::, and *Note
     environment-variables::.

There are some alternatives to running the `mysql_install_db' script
provided in the MySQL distribution:

   * If you want the initial privileges to be different from the
     standard defaults, you can modify `mysql_install_db' before you
     run it.  However, it is preferable to use `GRANT' and `REVOKE' to
     change the privileges _after_ the grant tables have been set up.
     In other words, you can run `mysql_install_db', and then use
     `mysql -u root mysql' to connect to the server as the MySQL `root'
     user so that you can issue the necessary `GRANT' and `REVOKE'
     statements.

     If you want to install MySQL on several machines with the same
     privileges, you can put the `GRANT' and `REVOKE' statements in a
     file and execute the file as a script using `mysql' after running
     `mysql_install_db'. For example:

          shell> bin/mysql_install_db --user=mysql
          shell> bin/mysql -u root < your_script_file

     By doing this, you can avoid having to issue the statements
     manually on each machine.

   * It is possible to re-create the grant tables completely after they
     have previously been created. You might want to do this if you're
     just learning how to use `GRANT' and `REVOKE' and have made so
     many modifications after running `mysql_install_db' that you want
     to wipe out the tables and start over.

     To re-create the grant tables, remove all the `.frm', `.MYI', and
     `.MYD' files in the `mysql' database directory. Then run the
     `mysql_install_db' script again.

   * You can start `mysqld' manually using the `--skip-grant-tables'
     option and add the privilege information yourself using `mysql':

          shell> bin/mysqld_safe --user=mysql --skip-grant-tables &
          shell> bin/mysql mysql

     From `mysql', manually execute the SQL commands contained in
     `mysql_install_db'.  Make sure that you run `mysqladmin
     flush-privileges' or `mysqladmin reload' afterward to tell the
     server to reload the grant tables.

     Note that by not using `mysql_install_db', you not only have to
     populate the grant tables manually, you also have to create them
     first.


File: manual.info,  Node: automatic-start,  Next: starting-server,  Prev: mysql-install-db-problems,  Up: unix-post-installation

2.10.2.2 Starting and Stopping MySQL Automatically
..................................................

Generally, you start the `mysqld' server in one of these ways:

   * By invoking `mysqld' directly. This works on any platform.

   * By running the MySQL server as a Windows service. The service can
     be set to start the server automatically when Windows starts, or
     as a manual service that you start on request. For instructions,
     see *Note windows-start-service::.

   * By invoking `mysqld_safe', which tries to determine the proper
     options for `mysqld' and then runs it with those options. This
     script is used on Unix and Unix-like systems. See *Note
     mysqld-safe::.

   * By invoking `mysql.server'. This script is used primarily at
     system startup and shutdown on systems that use System V-style run
     directories, where it usually is installed under the name `mysql'.
     The `mysql.server' script starts the server by invoking
     `mysqld_safe'. See *Note mysql-server::.

   * On Mac OS X, you can install a separate MySQL Startup Item package
     to enable the automatic startup of MySQL on system startup. The
     Startup Item starts the server by invoking `mysql.server'. See
     *Note mac-os-x-installation::, for details.

The `mysqld_safe' and `mysql.server' scripts and the Mac OS X Startup
Item can be used to start the server manually, or automatically at
system startup time.  `mysql.server' and the Startup Item also can be
used to stop the server.

To start or stop the server manually using the `mysql.server' script,
invoke it with `start' or `stop' arguments:

     shell> mysql.server start
     shell> mysql.server stop

Before `mysql.server' starts the server, it changes location to the
MySQL installation directory, and then invokes `mysqld_safe'. If you
want the server to run as some specific user, add an appropriate `user'
option to the `[mysqld]' group of the `/etc/my.cnf' option file, as
shown later in this section. (It is possible that you will need to edit
`mysql.server' if you've installed a binary distribution of MySQL in a
non-standard location. Modify it to `cd' into the proper directory
before it runs `mysqld_safe'. If you do this, your modified version of
`mysql.server' may be overwritten if you upgrade MySQL in the future,
so you should make a copy of your edited version that you can
reinstall.)

`mysql.server stop' stops the server by sending a signal to it. You can
also stop the server manually by executing `mysqladmin shutdown'.

To start and stop MySQL automatically on your server, you need to add
start and stop commands to the appropriate places in your `/etc/rc*'
files.

If you use the Linux server RPM package (`MySQL-server-VERSION.rpm'),
the `mysql.server' script is installed in the `/etc/init.d' directory
with the name `mysql'. You need not install it manually.  See *Note
linux-rpm::, for more information on the Linux RPM packages.

Some vendors provide RPM packages that install a startup script under a
different name such as `mysqld'.

If you install MySQL from a source distribution or using a binary
distribution format that does not install `mysql.server' automatically,
you can install it manually. The script can be found in the
`support-files' directory under the MySQL installation directory or in
a MySQL source tree.

To install `mysql.server' manually, copy it to the `/etc/init.d'
directory with the name `mysql', and then make it executable. Do this
by changing location into the appropriate directory where
`mysql.server' is located and executing these commands:

     shell> cp mysql.server /etc/init.d/mysql
     shell> chmod +x /etc/init.d/mysql

Older Red Hat systems use the `/etc/rc.d/init.d' directory rather than
`/etc/init.d'. Adjust the preceding commands accordingly.
Alternatively, first create `/etc/init.d' as a symbolic link that
points to `/etc/rc.d/init.d':

     shell> cd /etc
     shell> ln -s rc.d/init.d .

After installing the script, the commands needed to activate it to run
at system startup depend on your operating system.  On Linux, you can
use `chkconfig':

     shell> chkconfig --add mysql

On some Linux systems, the following command also seems to be necessary
to fully enable the `mysql' script:

     shell> chkconfig --level 345 mysql on

On FreeBSD, startup scripts generally should go in
`/usr/local/etc/rc.d/'. The `rc(8)' manual page states that scripts in
this directory are executed only if their basename matches the `*.sh'
shell filename pattern. Any other files or directories present within
the directory are silently ignored. In other words, on FreeBSD, you
should install the `mysql.server' script as
`/usr/local/etc/rc.d/mysql.server.sh' to enable automatic startup.

As an alternative to the preceding setup, some operating systems also
use `/etc/rc.local' or `/etc/init.d/boot.local' to start additional
services on startup. To start up MySQL using this method, you could
append a command like the one following to the appropriate startup file:

     /bin/sh -c 'cd /usr/local/mysql; ./bin/mysqld_safe --user=mysql &'

For other systems, consult your operating system documentation to see
how to install startup scripts.

You can add options for `mysql.server' in a global `/etc/my.cnf' file.
A typical `/etc/my.cnf' file might look like this:

     [mysqld]
     datadir=/usr/local/mysql/var
     socket=/var/tmp/mysql.sock
     port=3306
     user=mysql

     [mysql.server]
     basedir=/usr/local/mysql

The `mysql.server' script understands the following options: `basedir',
`datadir', and `pid-file'.  If specified, they _must_ be placed in an
option file, not on the command line.  `mysql.server' understands only
`start' and `stop' as command-line arguments.

The following table shows which option groups the server and each
startup script read from option files:

*Script*       *Option Groups*
`mysqld'       `[mysqld]', `[server]', `[mysqld-MAJOR_VERSION]'
`mysqld_safe'  `[mysqld]', `[server]', `[mysqld_safe]'
`mysql.server' `[mysqld]', `[mysql.server]', `[server]'

`[mysqld-MAJOR_VERSION]' means that groups with names like
`[mysqld-5.0]' and `[mysqld-5.1]' are read by servers having versions
5.0.x, 5.1.x, and so forth. This feature can be used to specify options
that can be read only by servers within a given release series.

For backward compatibility, `mysql.server' also reads the
`[mysql_server]' group and `mysqld_safe' also reads the `[safe_mysqld]'
group. However, you should update your option files to use the
`[mysql.server]' and `[mysqld_safe]' groups instead when using MySQL
5.1.

See *Note option-files::.


File: manual.info,  Node: starting-server,  Prev: automatic-start,  Up: unix-post-installation

2.10.2.3 Starting and Troubleshooting the MySQL Server
......................................................

This section provides troubleshooting suggestions for problems starting
the server on Unix. If you are using Windows, see *Note
windows-troubleshooting::.

If you have problems starting the server, here are some things to try:

   * Check the error log to see why the server does not start.

   * Specify any special options needed by the storage engines you are
     using.

   * Make sure that the server knows where to find the data directory.

   * Make sure that the server can access the data directory.  The
     ownership and permissions of the data directory and its contents
     must be set such that the server can read and modify them.

   * Verify that the network interfaces the server wants to use are
     available.

Some storage engines have options that control their behavior.  You can
create a `my.cnf' file and specify startup options for the engines that
you plan to use. If you are going to use storage engines that support
transactional tables (`InnoDB', `NDB'), be sure that you have them
configured the way you want before starting the server:

MySQL Enterprise

For expert advice on start-up options appropriate to your
circumstances, subscribe to The MySQL Enterprise Monitor.  For more
information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

   * If you are using `InnoDB' tables, see *Note innodb-configuration::.

   * If you are using MySQL Cluster, see *Note
     mysql-cluster-configuration::.

Storage engines will use default option values if you specify none, but
it is recommended that you review the available options and specify
explicit values for those for which the defaults are not appropriate
for your installation.

When the `mysqld' server starts, it changes location to the data
directory. This is where it expects to find databases and where it
expects to write log files. The server also writes the pid (process ID)
file in the data directory.

The data directory location is hardwired in when the server is
compiled. This is where the server looks for the data directory by
default. If the data directory is located somewhere else on your
system, the server will not work properly. You can determine what the
default path settings are by invoking `mysqld' with the `--verbose' and
`--help' options.

If the default locations don't match the MySQL installation layout on
your system, you can override them by specifying options to `mysqld' or
`mysqld_safe' on the command line or in an option file.

To specify the location of the data directory explicitly, use the
`--datadir' option. However, normally you can tell `mysqld' the
location of the base directory under which MySQL is installed and it
looks for the data directory there. You can do this with the
`--basedir' option.

To check the effect of specifying path options, invoke `mysqld' with
those options followed by the `--verbose' and `--help' options. For
example, if you change location into the directory where `mysqld' is
installed and then run the following command, it shows the effect of
starting the server with a base directory of `/usr/local':

     shell> ./mysqld --basedir=/usr/local --verbose --help

You can specify other options such as `--datadir' as well, but
`--verbose' and `--help' must be the last options.

Once you determine the path settings you want, start the server without
`--verbose' and `--help'.

If `mysqld' is currently running, you can find out what path settings
it is using by executing this command:

     shell> mysqladmin variables

Or:

     shell> mysqladmin -h HOST_NAME variables

HOST_NAME is the name of the MySQL server host.

If you get `Errcode 13' (which means `Permission denied') when starting
`mysqld', this means that the privileges of the data directory or its
contents do not allow the server access. In this case, you change the
permissions for the involved files and directories so that the server
has the right to use them. You can also start the server as `root', but
this raises security issues and should be avoided.

On Unix, change location into the data directory and check the
ownership of the data directory and its contents to make sure the
server has access. For example, if the data directory is
`/usr/local/mysql/var', use this command:

     shell> ls -la /usr/local/mysql/var

If the data directory or its files or subdirectories are not owned by
the login account that you use for running the server, change their
ownership to that account. If the account is named `mysql', use these
commands:

     shell> chown -R mysql /usr/local/mysql/var
     shell> chgrp -R mysql /usr/local/mysql/var

If the server fails to start up correctly, check the error log. Log
files are located in the data directory (typically `C:\Program
Files\MySQL\MySQL Server 5.1\data' on Windows, `/usr/local/mysql/data'
for a Unix binary distribution, and `/usr/local/var' for a Unix source
distribution). Look in the data directory for files with names of the
form `HOST_NAME.err' and `HOST_NAME.log', where HOST_NAME is the name
of your server host. Then examine the last few lines of these files.
On Unix, you can use `tail' to display them:

     shell> tail HOST_NAME.err
     shell> tail HOST_NAME.log

The error log should contain information that indicates why the server
couldn't start.

If either of the following errors occur, it means that some other
program (perhaps another `mysqld' server) is using the TCP/IP port or
Unix socket file that `mysqld' is trying to use:

     Can't start server: Bind on TCP/IP port: Address already in use
     Can't start server: Bind on unix socket...

Use `ps' to determine whether you have another `mysqld' server running.
If so, shut down the server before starting `mysqld' again. (If another
server is running, and you really want to run multiple servers, you can
find information about how to do so in *Note multiple-servers::.)

If no other server is running, try to execute the command `telnet
YOUR_HOST_NAME TCP_IP_PORT_NUMBER'. (The default MySQL port number is
3306.) Then press Enter a couple of times. If you don't get an error
message like `telnet: Unable to connect to remote host: Connection
refused', some other program is using the TCP/IP port that `mysqld' is
trying to use. You'll need to track down what program this is and
disable it, or else tell `mysqld' to listen to a different port with
the `--port' option. In this case, you'll also need to specify the port
number for client programs when connecting to the server via TCP/IP.

Another reason the port might be inaccessible is that you have a
firewall running that blocks connections to it. If so, modify the
firewall settings to allow access to the port.

If the server starts but you can't connect to it, you should make sure
that you have an entry in `/etc/hosts' that looks like this:

     127.0.0.1       localhost

This problem occurs only on systems that do not have a working thread
library and for which MySQL must be configured to use MIT-pthreads.

If you cannot get `mysqld' to start, you can try to make a trace file
to find the problem by using the `--debug' option. See MySQL Internals:
Porting (http://forge.mysql.com/wiki/MySQL_Internals_Porting).


File: manual.info,  Node: default-privileges,  Prev: unix-post-installation,  Up: post-installation

2.10.3 Securing the Initial MySQL Accounts
------------------------------------------

Part of the MySQL installation process is to set up the `mysql'
database that contains the grant tables:

   * Windows distributions contain preinitialized grant tables that are
     installed automatically.

   * On Unix, the grant tables are populated by the `mysql_install_db'
     program. Some installation methods run this program for you. Others
     require that you execute it manually. For details, see *Note
     unix-post-installation::.

The grant tables define the initial MySQL user accounts and their
access privileges. These accounts are set up as follows:

   * Accounts with the username `root' are created. These are superuser
     accounts that can do anything.  The initial `root' account
     passwords are empty, so anyone can connect to the MySQL server as
     `root' -- _without a password_ -- and be granted all privileges.

        * On Windows, one `root' account is created; this account
          allows connecting from the local host only. The Windows
          installer will optionally create an account allowing for
          connections from any host only if the user selects the
          `Enable root access from remote machines' option during
          installation.

        * On Unix, both `root' accounts are for connections from the
          local host. Connections must be made from the local host by
          specifying a hostname of `localhost' for one of the accounts,
          or the actual hostname or IP number for the other.

   * Two anonymous-user accounts are created, each with an empty
     username. The anonymous accounts have no password, so anyone can
     use them to connect to the MySQL server.

        * On Windows, one anonymous account is for connections from the
          local host. It has no global privileges.  (Before MySQL
          5.1.16, it has all global privileges, just like the `root'
          accounts.) The other is for connections from any host and has
          all privileges for the `test' database and for other
          databases with names that start with `test'.

        * On Unix, both anonymous accounts are for connections from the
          local host. Connections must be made from the local host by
          specifying a hostname of `localhost' for one of the accounts,
          or the actual hostname or IP number for the other. These
          accounts have all privileges for the `test' database and for
          other databases with names that start with `test_'.

As noted, none of the initial accounts have passwords. This means that
your MySQL installation is unprotected until you do something about it:

   * If you want to prevent clients from connecting as anonymous users
     without a password, you should either assign a password to each
     anonymous account or else remove the accounts.

   * You should assign a password to each MySQL `root' account.

The following instructions describe how to set up passwords for the
initial MySQL accounts, first for the anonymous accounts and then for
the `root' accounts. Replace `NEWPWD' in the examples with the actual
password that you want to use. The instructions also cover how to
remove the anonymous accounts, should you prefer not to allow anonymous
access at all.

You might want to defer setting the passwords until later, so that you
don't need to specify them while you perform additional setup or
testing. However, be sure to set them before using your installation
for production purposes.

*Anonymous Account Password Assignment*

To assign passwords to the anonymous accounts, connect to the server as
`root' and then use either `SET PASSWORD' or `UPDATE'. In either case,
be sure to encrypt the password using the `PASSWORD()' function.

To use `SET PASSWORD' on Windows, do this:

     shell> mysql -u root
     mysql> SET PASSWORD FOR ''@'localhost' = PASSWORD('NEWPWD');
     mysql> SET PASSWORD FOR ''@'%' = PASSWORD('NEWPWD');

To use `SET PASSWORD' on Unix, do this:

     shell> mysql -u root
     mysql> SET PASSWORD FOR ''@'localhost' = PASSWORD('NEWPWD');
     mysql> SET PASSWORD FOR ''@'HOST_NAME' = PASSWORD('NEWPWD');

In the second `SET PASSWORD' statement, replace HOST_NAME with the name
of the server host. This is the name that is specified in the `Host'
column of the non-`localhost' record for `root' in the `user' table. If
you don't know what hostname this is, issue the following statement
before using `SET PASSWORD':

     mysql> SELECT Host, User FROM mysql.user;

Look for the record that has `root' in the `User' column and something
other than `localhost' in the `Host' column. Then use that `Host' value
in the second `SET PASSWORD' statement.

*Anonymous Account Removal*

If you prefer to remove the anonymous accounts instead, do so as
follows:

     shell> mysql -u root
     mysql> DROP USER '';

The `DROP' statement applies both to Windows and to Unix. On Windows,
if you want to remove only the anonymous account that has the same
privileges as `root', do this instead:

     shell> mysql -u root
     mysql> DROP USER ''@'localhost';

That account allows anonymous access but has full privileges, so
removing it improves security.

*`root' Account Password Assignment*

You can assign passwords to the `root' accounts in several ways. The
following discussion demonstrates three methods:

   * Use the `SET PASSWORD' statement

   * Use the `mysqladmin' command-line client program

   * Use the `UPDATE' statement

To assign passwords using `SET PASSWORD', connect to the server as
`root' and issue `SET PASSWORD' statements. Be sure to encrypt the
password using the `PASSWORD()' function.

For Windows, do this:

     shell> mysql -u root
     mysql> SET PASSWORD FOR 'root'@'localhost' = PASSWORD('NEWPWD');
     mysql> SET PASSWORD FOR 'root'@'%' = PASSWORD('NEWPWD');

For Unix, do this:

     shell> mysql -u root
     mysql> SET PASSWORD FOR 'root'@'localhost' = PASSWORD('NEWPWD');
     mysql> SET PASSWORD FOR 'root'@'HOST_NAME' = PASSWORD('NEWPWD');

In the second `SET PASSWORD' statement, replace HOST_NAME with the name
of the server host. This is the same hostname that you used when you
assigned the anonymous account passwords.

If the `user' table contains an account with `User' and `Host' values of
`'root'' and `'127.0.0.1'', use an additional `SET PASSWORD' statement
to set that account's password:

     mysql> SET PASSWORD FOR 'root'@'127.0.0.1' = PASSWORD('NEWPWD');

To assign passwords to the `root' accounts using `mysqladmin', execute
the following commands:

     shell> mysqladmin -u root password "NEWPWD"
     shell> mysqladmin -u root -h HOST_NAME password "NEWPWD"

These commands apply both to Windows and to Unix. In the second
command, replace HOST_NAME with the name of the server host. The double
quotes around the password are not always necessary, but you should use
them if the password contains spaces or other characters that are
special to your command interpreter.

The `mysqladmin' method of setting the `root' account passwords does
not set the password for the `'root'@'127.0.0.1'' account.  To do so,
use `SET PASSWORD' as shown earlier.

You can also use `UPDATE' to modify the `user' table directly. The
following `UPDATE' statement assigns a password to all `root' accounts:

     shell> mysql -u root
     mysql> UPDATE mysql.user SET Password = PASSWORD('NEWPWD')
         ->     WHERE User = 'root';
     mysql> FLUSH PRIVILEGES;

The `UPDATE' statement applies both to Windows and to Unix.

After the passwords have been set, you must supply the appropriate
password whenever you connect to the server. For example, if you want
to use `mysqladmin' to shut down the server, you can do so using this
command:

     shell> mysqladmin -u root -p shutdown
     Enter password: (ENTER ROOT PASSWORD HERE)

*Note*:

If you forget your `root' password after setting it up, *Note
resetting-permissions::, covers the procedure for resetting it.

To set up additional accounts, you can use the `GRANT' statement. For
instructions, see *Note adding-users::.


File: manual.info,  Node: upgrade,  Next: downgrading,  Prev: post-installation,  Up: installing

2.11 Upgrading MySQL
====================

* Menu:

* upgrading-from-5-0::           Upgrading from MySQL 5.0 to 5.1
* upgrading-to-arch::            Copying MySQL Databases to Another Machine

As a general rule, we recommend that when you upgrade from one release
series to another, you should go to the next series rather than
skipping a series. If you wish to upgrade from a release series
previous to MySQL 5.0, you should upgrade to each successive release
series in turn until you have reached MySQL 5.0, and then proceed with
the upgrade to MySQL 5.1. For example, if you currently are running
MySQL 4.0 and wish to upgrade to a newer series, upgrade to MySQL 4.1
first before upgrading to 5.0, and so forth. For information on
upgrading to MySQL 5.0, see the `MySQL 5.0 Reference Manual'; for
earlier releases, see the `MySQL 3.23, 4.0, 4.1 Reference Manual'.

The following items form a checklist of things that you should do
whenever you perform an upgrade from MySQL 5.0 to 5.1:

   * Before any upgrade, back up your databases, including the `mysql'
     database that contains the grant tables.

   * Read _all_ the notes in *Note upgrading-from-5-0::. These notes
     will enable you to identify upgrade issues that apply to your
     current MySQL installation. Read *Note news:: as well, which
     provides information about features that are new in MySQL 5.1 or
     differ from those found in MySQL 5.0.

   * For any incompatibilities that require your attention _before_
     upgrading, deal with them as described in *Note
     upgrading-from-5-0::.

   * After you upgrade to a new version of MySQL, you should run
     `mysql_upgrade' (see *Note mysql-upgrade::). This program will
     check your tables, and repair them if necessary. It will also
     update your grant tables to make sure that they have the current
     structure so that you can take advantage of any new capabilities.
     (Some releases of MySQL introduce changes to the structure of the
     grant tables to add new privileges or features.)

   * If you are running MySQL Server on Windows, see *Note
     windows-upgrading::.

   * If you are using replication, see *Note replication-upgrade::, for
     information on upgrading your replication setup.

   * If you are upgrading an installation originally produced by
     installing multiple RPM packages, it is best to upgrade all the
     packages, not just some. For example, if you previously installed
     the server and client RPMs, do not upgrade just the server RPM.

   * As of MySQL 5.1.9, the `mysqld-max' server is included in binary
     distributions. There is no separate MySQL-Max distribution. As of
     MySQL 5.1.12, binary distributions contain a server that includes
     the features previously included in `mysqld-max'.

   * If you have created a user-defined function (UDF) with a given
     name and upgrade MySQL to a version that implements a new built-in
     function with the same name, the UDF becomes inaccessible. To
     correct this, use `DROP FUNCTION' to drop the UDF, and then use
     `CREATE FUNCTION' to re-create the UDF with a different
     non-conflicting name. The same is true if the new version of MySQL
     implements a built-in function with the same name as an existing
     stored function. See *Note function-resolution::, for the rules
     describing how the server interprets references to different kinds
     of functions.

You can always move the MySQL format files and data files between
different versions on the same architecture as long as you stay within
versions for the same release series of MySQL.

If you are cautious about using new versions, you can always rename
your old `mysqld' before installing a newer one. For example, if you
are using MySQL 5.0.13 and want to upgrade to 5.1.10, rename your
current server from `mysqld' to `mysqld-5.0.13'. If your new `mysqld'
then does something unexpected, you can simply shut it down and restart
with your old `mysqld'.

If, after an upgrade, you experience problems with recompiled client
programs, such as `Commands out of sync' or unexpected core dumps, you
probably have used old header or library files when compiling your
programs. In this case, you should check the date for your `mysql.h'
file and `libmysqlclient.a' library to verify that they are from the
new MySQL distribution. If not, recompile your programs with the new
headers and libraries.

If problems occur, such as that the new `mysqld' server does not start
or that you cannot connect without a password, verify that you do not
have an old `my.cnf' file from your previous installation.  You can
check this with the `--print-defaults' option (for example, `mysqld
--print-defaults').  If this command displays anything other than the
program name, you have an active `my.cnf' file that affects server or
client operation.

It is a good idea to rebuild and reinstall the Perl `DBD::mysql' module
whenever you install a new release of MySQL. The same applies to other
MySQL interfaces as well, such as the PHP `mysql' extension and the
Python `MySQLdb' module.


File: manual.info,  Node: upgrading-from-5-0,  Next: upgrading-to-arch,  Prev: upgrade,  Up: upgrade

2.11.1 Upgrading from MySQL 5.0 to 5.1
--------------------------------------

*After upgrading a 5.0 installation to 5.0.10 or above*, it is
_necessary_ to upgrade your grant tables. Otherwise, creating stored
procedures and functions might not work. The procedure for doing this
is described in *Note mysql-upgrade::.

*Note*:

It is good practice to back up your data before installing any new
version of software. Although MySQL works very hard to ensure a high
level of quality, you should protect your data by making a backup.
MySQL recommends that you dump and reload your tables from any previous
version to upgrade to 5.1.

In general, you should do the following when upgrading from MySQL 5.0
to 5.1:

   * Read _all_ the items in the following sections to see whether any
     of them might affect your applications:

        * *Note upgrade::, has general update information.

        * The items in the change lists found later in this section
          enable you to identify upgrade issues that apply to your
          current MySQL installation.

        * The MySQL 5.1 change history describes significant new
          features you can use in 5.1 or that differ from those found
          in MySQL 5.0. Some of these changes may result in
          incompatibilities. See *Note news-5-1-x::.

   * Note particularly any changes that are marked *Known issue* or
     *Incompatible change*. These incompatibilities with earlier
     versions of MySQL may require your attention _before you upgrade_.

     Our aim is to avoid these changes, but occasionally they are
     necessary to correct problems that would be worse than an
     incompatibility between releases. If any upgrade issue applicable
     to your installation involves an incompatibility that requires
     special handling, follow the instructions given in the
     incompatibility description. Often this will involve a dump and
     reload, or use of a statement such as `CHECK TABLE' or `REPAIR
     TABLE'.

     A dump and reload is done like this:

        * Dump the affected tables with `mysqldump' _before_ upgrading

        * Reload the dump file (for example, with `mysql') to recreate
          the tables after upgrading

     Any procedure that involves `REPAIR TABLE' with the `USE_FRM'
     option _must_ be done before upgrading. Use of this statement with
     a version of MySQL different from the one used to create the table
     (that is, using it after upgrading) may damage the table. See
     *Note repair-table::.

   * After you upgrade to a new version of MySQL, run `mysql_upgrade'
     (see *Note mysql-upgrade::). This program will check your tables,
     and repair them if necessary. It will also update your grant
     tables to make sure that they have the current structure so that
     you can take advantage of any new capabilities. (Some releases of
     MySQL introduce changes to the structure of the grant tables to
     add new privileges or features.)

   * If you are running MySQL Server on Windows, see *Note
     windows-upgrading::.

   * If you are using replication, see *Note replication-upgrade::, for
     information on upgrading your replication setup.

The following lists describe changes that may affect applications and
that you should watch out for when upgrading to MySQL 5.1.

*Configuration Changes:*

   * Before MySQL 5.1.11, to build MySQL from source with SSL support
     enabled, you would invoke `configure' with either the
     `--with-openssl' or `--with-yassl' option. In MySQL 5.1.11, those
     options both have been replaced by the `--with-ssl' option. By
     default, `--with-ssl' causes the bundled yaSSL library to be used.
     To select OpenSSL instead, give the option as `--with-ssl=PATH',
     where PATH is the directory where the OpenSSL header files and
     libraries are located.

*Server Changes:*

   * *Known issue*: MySQL introduces encoding for table names that have
     non-ASCII characters (see *Note identifier-mapping::). After a
     live upgrade from MySQL 5.0 to 5.1, the server recognizes names
     that have non-ASCII characters and adds a `#mysql50#' prefix to
     them. Running `mysqlcheck' later (or `mysql_upgrade', which runs
     `mysqlcheck') to upgrade these names encodes them with the new
     format and removes the `#mysql50#' prefix. However, although this
     is done for tables, it is not done for views. To work around this
     problem, drop each affected view and recreate it.

     This problem is fixed as of MySQL 5.1.23.

   * *Known issue*: When upgrading from MySQL 5.0 to 5.1, running
     `mysqlcheck' (or `mysql_upgrade', which runs `mysqlcheck') to
     upgrade tables fails for names that must be written as quoted
     identifiers. To work around this problem, rename each affected
     table to a name that does not require quoting:

          RENAME TABLE `tab``le_a` TO table_a;
          RENAME TABLE `table b` TO table_b;

     After renaming the tables, run the `mysql_upgrade' program. Then
     rename the tables back to their original names:

          RENAME TABLE table_a TO `tab``le_a`;
          RENAME TABLE table_b TO `table b`;

     This problem is fixed as of MySQL 5.1.23.

   * *Incompatible change*: In MySQL 5.1.25, a change was made to the
     way that the server handles prepared statements. This affects
     prepared statements processed at the SQL level (using the
     `PREPARE' statement) and those processed using the binary
     client-server protocol (using the *Note `mysql_stmt_prepare()':
     mysql-stmt-prepare. C API function).

     Previously, changes to metadata of tables or views referred to in
     a prepared statement could cause a server crash when the statement
     was next executed, or perhaps an error at execute time with a
     crash occurring later. For example, this could happen after
     dropping a table and recreating it with a different definition.

     Now metadata changes to tables or views referred to by prepared
     statements are detected and cause automatic repreparation of the
     statement when it is next executed.  Metadata changes occur for
     DDL statements such as those that create, drop, alter, rename, or
     truncate tables, or that analyze, optimize, or repair tables.
     Repreparation also occurs after referenced tables or views are
     flushed from the table definition cache, either implicitly to make
     room for new entries in the cache, or explicitly due to `FLUSH
     TABLES'.

     Repreparation is automatic, but to the extent that it occurs,
     performance of prepared statements is diminished.

     Table content changes (for example, with `INSERT' or `UPDATE') do
     not cause repreparation, nor do `SELECT' statements.

     An incompatibility with previous versions of MySQL is that a
     prepared statement may now return a different set of columns or
     different column types from one execution to the next.  For
     example, if the prepared statement is `SELECT * FROM t1', altering
     `t1' to contain a different number of columns causes the next
     execution to return a number of columns different from the previous
     execution.

     Older versions of the client library cannot handle this change in
     behavior. For applications that use prepared statements with the
     new server, an upgrade to the new client library is strongly
     recommended.

     Along with this change to statement repreparation, the default
     value of the `table_definition_cache' system variable has been
     increased from 128 to 256. The purpose of this increase is to
     lessen the chance that prepared statements will need repreparation
     due to referred-to tables/views having been flushed from the cache
     to make room for new entries.

     A new status variable, `Com_stmt_reprepare', has been introduced
     to track the number of repreparations.

   * *Incompatible change*: In MySQL 5.1.24, the `utf8_general_ci' and
     `ucs2_general_ci' collations were fixed to sort the letter "U+00DF
     SHARP S" equal to `'s''. As a result of this fix, any indexes on
     columns that use these collations (but only columns that use SHARP
     S) must be rebuilt when upgrading to 5.1.24 or higher. To do this,
     use `ALTER TABLE' to drop and re-add the indexes, or `mysqldump'
     to dump the affected tables and `mysql' to reload the dump file.

   * *Incompatible change*: MySQL 5.1 implements support for a plugin
     API that allows the loading and unloading of components at runtime,
     without restarting the server. *Note plugin-api::.  The plugin API
     requires the `mysql.plugin' table. After upgrading from an older
     version of MySQL, you should run the `mysql_upgrade' command to
     create this table. See *Note mysql-upgrade::.

     Plugins are installed in the directory named by the `plugin_dir'
     system variable. This variable also controls the location from
     which the server loads user-defined functions (UDFs), which is a
     change from earlier versions of MySQL. That is, all UDF library
     files now must be installed in the plugin directory. When
     upgrading from an older version of MySQL, you must migrate your
     UDF files to the plugin directory.

   * *Incompatible change*: The `table_cache' system variable has been
     renamed to `table_open_cache'. Any scripts that refer to
     `table_cache' should be updated to use the new name.

   * *Incompatible change*: Several issues were identified for stored
     programs (stored functions and procedures, triggers, and events)
     and views containing non-ASCII symbols. These issues involved
     conversion errors due to incomplete character set information when
     translating these objects to and from stored format.

     To address these problems, the representation for these objects
     was changed in MySQL 5.1.21. However, the fixes affect _all_
     stored programs and views.  (For example, you will see warnings
     about `no creation context.') To avoid warnings from the server
     about the use of old definitions from any release prior to 5.1.21,
     you should dump stored programs and views with `mysqldump' after
     upgrading to 5.1.21 or higher, and then reload them to recreate
     them with new definitions. Invoke `mysqldump' with a
     `--default-character-set' option that names the non-ASCII
     character set that was used for the definitions when the objects
     were originally defined.

   * *Incompatible change*: As of MySQL 5.1.20, `mysqld_safe' supports
     error logging to `syslog' on systems that support the `logger'
     command. The new `--syslog' and `--skip-syslog' options can be
     used instead of the `--log-error' option to control logging
     behavior, as described in *Note mysqld-safe::.

     In 5.1.21 and up, the default is `--skip-syslog', which is
     compatible with the default behavior of writing an error log file
     for releases prior to 5.1.20.

     *In 5.1.20 _only_, the following conditions apply*: 1) The default
     is to use `syslog', which is not compatible with releases prior to
     5.1.20. 2) Logging to `syslog' may fail to operate correctly in
     some cases, so we recommend that you use `--skip-syslog' or
     `--log-error'. To maintain the older behavior if you were using no
     error-logging option, use `--skip-syslog'. If you were using
     `--log-error', continue to use it.

   * *Incompatible change*: As of MySQL 5.1.15, `InnoDB' rolls back
     only the last statement on a transaction timeout. A new option,
     `--innodb_rollback_on_timeout', causes `InnoDB' to abort and roll
     back the entire transaction if a transaction timeout occurs (the
     same behavior as in MySQL 4.1).

   * *Incompatible change*: As of MySQL 5.1.15, the following
     conditions apply to enabling the `read_only' system variable:

        * If you attempt to enable `read_only' while you have any
          explicit locks (acquired with `LOCK TABLES' or have a pending
          transaction, an error will occur.

        * If other clients hold explicit table locks or have pending
          transactions, the attempt to enable `read_only' blocks until
          the locks are released and the transactions end. While the
          attempt to enable `read_only' is pending, requests by other
          clients for table locks or to begin transactions also block
          until `read_only' has been set.

        * `read_only' can be enabled while you hold a global read lock
          (acquired with `FLUSH TABLES WITH READ LOCK') because that
          does not involve table locks.

     Previously, the attempt to enable `read_only' would return
     immediately even if explicit locks or transactions were pending,
     so some data changes could occur for statements executing in the
     server at the same time.

   * *Incompatible change*: The number of function names affected by
     `IGNORE_SPACE' was reduced significantly in MySQL 5.1.13, from
     about 200 to about 30. (For details about `IGNORE_SPACE', see
     *Note function-resolution::.) This change improves the consistency
     of parser operation. However, it also introduces the possibility
     of incompatibility for old SQL code that relies on the following
     conditions:

        * `IGNORE_SPACE' is disabled.

        * The presence or absence of whitespace following a function
          name is used to distinguish between a built-in function and
          stored function that have the same name (for example, `PI()'
          versus `PI ()').

     For functions that are no longer affected by `IGNORE_SPACE' as of
     MySQL 5.1.13, that strategy no longer works. Either of the
     following approaches can be used if you have code that is subject
     to the preceding incompatibility:

        * If a stored function has a name that conflicts with a
          built-in function, refer to the stored function with a schema
          name qualifier, regardless of whether whitespace is present.
          For example, write `SCHEMA_NAME.PI()' or `SCHEMA_NAME.PI ()'.

        * Alternatively, rename the stored function to use a
          non-conflicting name and change invocations of the function
          to use the new name.

   * *Incompatible change*: For `utf8' columns, the full-text parser
     incorrectly considered several non-word punctuation and whitespace
     characters as word characters, causing some searches to return
     incorrect results. The fix involves a change to the full-text
     parser in MySQL 5.1.12, so as of 5.1.12, any tables that have
     `FULLTEXT' indexes on `utf8' columns must be repaired with `REPAIR
     TABLE':

          REPAIR TABLE TBL_NAME QUICK;

   * *Incompatible change*: Storage engines can be pluggable at
     runtime, so the distinction between disabled and invalid storage
     engines no longer applies. As of MySQL 5.1.12, this affects the
     `NO_ENGINE_SUBSTITUTION' SQL mode, as described in *Note
     server-sql-mode::.

   * *Incompatible change*: The structure of `FULLTEXT' indexes has been
     changed in MySQL 5.1.6. After upgrading to MySQL 5.1.6 or greater,
     use the `REPAIR TABLE ... QUICK' statement for each table that
     contains any `FULLTEXT' indexes.

   * *Incompatible change*: In MySQL 5.1.6, when log tables were
     implemented, the default log destination for the general query and
     slow query log was `TABLE'. As of MySQL 5.1.21, this default has
     been changed to `FILE', which is compatible with MySQL 5.0, but
     incompatible with earlier releases of MySQL 5.1 from 5.1.6 to
     5.1.20. If you are upgrading from MySQL 5.0 to this release, no
     logging option changes should be necessary. However, if you are
     upgrading from 5.1.6 through 5.1.20 to this release and were using
     `TABLE' logging, use the `--log-output=TABLE' option explicitly to
     preserve your server's table-logging behavior.

   * *Incompatible change*: For `ENUM' columns that had enumeration
     values containing commas, the commas were mapped to 0xff
     internally. However, this rendered the commas indistinguishable
     from true 0xff characters in the values.  This no longer occurs.
     However, the fix requires that you dump and reload any tables that
     have `ENUM' columns containing true 0xff in their values: Dump the
     tables using `mysqldump' with the current server before upgrading
     from a version of MySQL 5.1 older than 5.1.15 to version 5.1.15 or
     newer.

   * As of MySQL 5.1.12, the `lc_time_names' system variable specifies
     the locale that controls the language used to display day and
     month names and abbreviations. This variable affects the output
     from the `DATE_FORMAT()', `DAYNAME()' and `MONTHNAME()' functions.
     See *Note locale-support::.

   * As of MySQL 5.1.6, special characters in database and table
     identifiers are encoded when creating the corresponding directory
     names and filenames. This relaxes the restrictions on the
     characters that can appear in identifiers. See *Note
     identifier-mapping::. To cause database and table names to be
     updated to the new format should they contain special characters,
     re-encode them with `mysqlcheck'. The following command updates
     all names to the new encoding:

          shell> mysqlcheck --check-upgrade --fix-db-names --fix-table-names --all-databases

     `mysqlcheck' cannot fix names that contain literal instances of
     the `@' character that is used for encoding special characters. If
     you have databases or tables that contain this character, use
     `mysqldump' to dump them before upgrading to MySQL 5.1.6 or later,
     and then reload the dump file after upgrading.

   * As of MySQL 5.1.9, `mysqld_safe' no longer implicitly invokes
     `mysqld-max' if it exists. Instead, it invokes `mysqld' unless a
     `--mysqld' or `--mysqld-version' option is given to specify
     another server explicitly. If you previously relied on the
     implicit invocation of `mysqld-max', you should use an appropriate
     option now.

*SQL Changes:*

   * *Incompatible change:* Multiple-table `DELETE' statements
     containing ambiguous aliases could have unintended side effects
     such as deleting rows from the wrong table. Example:

          DELETE FROM t1 AS a2 USING t1 AS a1 INNER JOIN t2 AS a2;

     As of MySQL 5.1.23, alias declarations can be declared only in the
     TABLE_REFERENCES part.  Elsewhere in the statement, alias
     references are allowed but not alias declarations. Statements
     containing aliases that are no longer allowed must be rewritten.

   * *Important note*: Prior to MySQL 5.1.17, the parser accepted
     invalid code in SQL condition handlers, leading to server crashes
     or unexpected execution behavior in stored programs. Specifically,
     the parser allowed a condition handler to refer to labels for
     blocks that enclose the handler declaration. This was incorrect
     because block label scope does not include the code for handlers
     declared within the labeled block.

     As of 5.1.17, the parser rejects this invalid construct, but if
     you upgrade in place (without dumping and reloading your
     databases), existing handlers that contain the construct still are
     invalid _even if they appear to function as you expect_ and should
     be rewritten.

     To find affected handlers, use mysqldump to dump all stored
     functions and procedures, triggers, and events. Then attempt to
     reload them into an upgraded server. Handlers that contain illegal
     label references will be rejected.

     For more information about condition handlers and writing them to
     avoid invalid jumps, see *Note declare-handlers::.

   * *Incompatible change:* The parser accepted statements that
     contained `/* ...  */' that were not properly closed with `*/',
     such as `SELECT 1 /* + 2'. As of MySQL 5.1.23, statements that
     contain unclosed `/*'-comments now are rejected with a syntax
     error.

     This fix has the potential to cause incompatibilities.  Because of
     Bug#26302 (http://bugs.mysql.com/26302), which caused the trailing
     `*/' to be truncated from comments in views, stored routines,
     triggers, and events, it is possible that objects of those types
     may have been stored with definitions that now will be rejected as
     syntactically invalid. Such objects should be dropped and
     re-created so that their definitions do not contain truncated
     comments.

   * *Incompatible change*: As of MySQL 5.1.8, `TYPE = ENGINE_NAME' is
     still accepted as a synonym for the `ENGINE = ENGINE_NAME' table
     option but generates a warning. You should note that this option
     is not available in MySQL 5.1.7, and *is removed altogether as of
     MySQL 5.2.5 and produces a syntax error*.

     `TYPE' has been deprecated since MySQL 4.0.

   * *Incompatible change:* The namespace for triggers has changed in
     MySQL 5.0.10.  Previously, trigger names had to be unique per
     table. Now they must be unique within the schema (database). An
     implication of this change is that `DROP TRIGGER' syntax now uses
     a schema name instead of a table name (schema name is optional
     and, if omitted, the current schema will be used).

     When upgrading from a previous version of MySQL 5 to MySQL 5.0.10
     or newer, you must drop all triggers and re-create them or `DROP
     TRIGGER' will not work after the upgrade. Here is a suggested
     procedure for doing this:

       1. Upgrade to MySQL 5.0.10 or later to be able to access trigger
          information in the `INFORMATION_SCHEMA.TRIGGERS' table.  (It
          should work even for pre-5.0.10 triggers.)

       2. Dump all trigger definitions using the following `SELECT'
          statement:

               SELECT CONCAT('CREATE TRIGGER ', t.TRIGGER_SCHEMA, '.', t.TRIGGER_NAME,
                             ' ', t.ACTION_TIMING, ' ', t.EVENT_MANIPULATION, ' ON ',
                             t.EVENT_OBJECT_SCHEMA, '.', t.EVENT_OBJECT_TABLE,
                             ' FOR EACH ROW ', t.ACTION_STATEMENT, '//' )
               INTO OUTFILE '/tmp/triggers.sql'
               FROM INFORMATION_SCHEMA.TRIGGERS AS t;

          The statement uses `INTO OUTFILE', so you must have the
          `FILE' privilege. The file will be created on the server
          host; use a different filename if you like. To be 100% safe,
          inspect the trigger definitions in the `triggers.sql' file,
          and perhaps make a backup of the file.

       3. Stop the server and drop all triggers by removing all `.TRG'
          files in your database directories. Change location to your
          data directory and issue this command:

               shell> rm */*.TRG

       4. Start the server and re-create all triggers using the
          `triggers.sql' file: For example in my case it was:

               mysql> delimiter // ;
               mysql> source /tmp/triggers.sql //

       5. Check that all triggers were successfully created using the
          `SHOW TRIGGERS' statement.

   * *Incompatible change*: MySQL 5.1.6 introduces the `TRIGGER'
     privilege.  Previously, the `SUPER' privilege was needed to create
     or drop triggers. Now those operations require the `TRIGGER'
     privilege. This is a security improvement because you no longer
     need to grant users the `SUPER' privilege to enable them to create
     triggers. However, the requirement that the account named in a
     trigger's `DEFINER' clause must have the `SUPER' privilege has
     changed to a requirement for the `TRIGGER' privilege. When
     upgrading from a previous version of MySQL 5.0 or 5.1 to MySQL
     5.1.6 or newer, be sure to update your grant tables as described in
     *Note mysql-upgrade::. This process assigns the `TRIGGER'
     privilege to all accounts that had the `SUPER' privilege. If you
     fail to update the grant tables, triggers may fail when activated.
     (After updating the grant tables, you can revoke the `SUPER'
     privilege from those accounts that no longer otherwise require it.)

   * Some keywords are reserved in MySQL 5.1 that were not reserved in
     MySQL 5.0. See *Note reserved-words::.

   * The `LOAD DATA FROM MASTER' and `LOAD TABLE FROM MASTER'
     statements are deprecated. See *Note load-data-from-master::, for
     recommended alternatives.

   * The `INSTALL PLUGIN' and `UNINSTALL PLUGIN' statements that are
     used for the plugin API are new. So is the `WITH PARSER' clause for
     `FULLTEXT' index creation that associates a parser plugin with a
     full-text index.  *Note plugin-api::.

*C API Changes:*

   * *Incompatible change*: As of MySQL 5.1.7, the *Note
     `mysql_stmt_attr_get()': mysql-stmt-attr-get. C API function
     returns a boolean rather than an unsigned int for
     `STMT_ATTR_UPDATE_MAX_LENGTH'. (Bug#16144
     (http://bugs.mysql.com/16144))


File: manual.info,  Node: upgrading-to-arch,  Prev: upgrading-from-5-0,  Up: upgrade

2.11.2 Copying MySQL Databases to Another Machine
-------------------------------------------------

You can copy the `.frm', `.MYI', and `.MYD' files for `MyISAM' tables
between different architectures that support the same floating-point
format.  (MySQL takes care of any byte-swapping issues.) See *Note
myisam-storage-engine::.

In cases where you need to transfer databases between different
architectures, you can use `mysqldump' to create a file containing SQL
statements. You can then transfer the file to the other machine and
feed it as input to the `mysql' client.

Use `mysqldump --help' to see what options are available. If you are
moving the data to a newer version of MySQL, you should use `mysqldump
--opt' to take advantage of any optimizations that result in a dump
file that is smaller and can be processed more quickly.

The easiest (although not the fastest) way to move a database between
two machines is to run the following commands on the machine on which
the database is located:

     shell> mysqladmin -h 'OTHER_HOSTNAME' create DB_NAME
     shell> mysqldump --opt DB_NAME | mysql -h 'OTHER_HOSTNAME' DB_NAME

If you want to copy a database from a remote machine over a slow
network, you can use these commands:

     shell> mysqladmin create DB_NAME
     shell> mysqldump -h 'OTHER_HOSTNAME' --opt --compress DB_NAME | mysql DB_NAME

You can also store the dump in a file, transfer the file to the target
machine, and then load the file into the database there.  For example,
you can dump a database to a compressed file on the source machine like
this:

     shell> mysqldump --quick DB_NAME | gzip > DB_NAME.gz

Transfer the file containing the database contents to the target
machine and run these commands there:

     shell> mysqladmin create DB_NAME
     shell> gunzip < DB_NAME.gz | mysql DB_NAME

You can also use `mysqldump' and `mysqlimport' to transfer the
database. For large tables, this is much faster than simply using
`mysqldump'. In the following commands, DUMPDIR represents the full
pathname of the directory you use to store the output from `mysqldump'.

First, create the directory for the output files and dump the database:

     shell> mkdir DUMPDIR
     shell> mysqldump --tab=DUMPDIR DB_NAME

Then transfer the files in the DUMPDIR directory to some corresponding
directory on the target machine and load the files into MySQL there:

     shell> mysqladmin create DB_NAME           # create database
     shell> cat DUMPDIR/*.sql | mysql DB_NAME   # create tables in database
     shell> mysqlimport DB_NAME DUMPDIR/*.txt   # load data into tables

Do not forget to copy the `mysql' database because that is where the
grant tables are stored. You might have to run commands as the MySQL
`root' user on the new machine until you have the `mysql' database in
place.

After you import the `mysql' database on the new machine, execute
`mysqladmin flush-privileges' so that the server reloads the grant
table information.


File: manual.info,  Node: downgrading,  Next: operating-system-specific-notes,  Prev: upgrade,  Up: installing

2.12 Downgrading MySQL
======================

* Menu:

* downgrading-to-5-0::           Downgrading to MySQL 5.0

This section describes what you should do to downgrade to an older
MySQL version in the unlikely case that the previous version worked
better than the new one.

If you are downgrading within the same release series (for example,
from 5.0.13 to 5.0.12) the general rule is that you just have to
install the new binaries on top of the old ones. There is no need to do
anything with the databases. As always, however, it is always a good
idea to make a backup.

The following items form a checklist of things you should do whenever
you perform a downgrade:

   * Read the upgrading section for the release series from which you
     are downgrading to be sure that it does not have any features you
     really need. *Note upgrade::.

   * If there is a downgrading section for that version, you should
     read that as well.

In most cases, you can move the MySQL format files and data files
between different versions on the same architecture as long as you stay
within versions for the same release series of MySQL.

If you downgrade from one release series to another, there may be
incompatibilities in table storage formats. In this case, you can use
`mysqldump' to dump your tables before downgrading. After downgrading,
reload the dump file using `mysql' or `mysqlimport' to re-create your
tables. For examples, see *Note upgrading-to-arch::.

The normal symptom of a downward-incompatible table format change when
you downgrade is that you can't open tables. In that case, use the
following procedure:

  1. Stop the older MySQL server that you are downgrading to.

  2. Restart the newer MySQL server you are downgrading from.

  3. Dump any tables that were inaccessible to the older server by
     using `mysqldump' to create a dump file.

  4. Stop the newer MySQL server and restart the older one.

  5. Reload the dump file into the older server. Your tables should be
     accessible.


File: manual.info,  Node: downgrading-to-5-0,  Prev: downgrading,  Up: downgrading

2.12.1 Downgrading to MySQL 5.0
-------------------------------

When downgrading to MySQL 5.0 from MySQL 5.1 or a later version, you
should keep in mind the following issues relating to features found in
MySQL 5.1 and later, but not in MySQL 5.0:

   * Event Scheduler

     MySQL 5.0 does not support scheduled events. If your databases
     contain scheduled event definitions, you should prevent them from
     being dumped when you use `mysqldump' by using the `--skip-events'
     option. (See *Note mysqldump::.)

   * Partitioning

     MySQL 5.0 does not support user-defined partitioning. If a table
     was created as a partitioned table in 5.1 (or if an table created
     in a previous version of MySQL was altered to include partitions
     after an upgrade to 5.1), the table is accessible after downgrade
     only if you do one of the following:

        * Export the table using `mysqldump' and then drop it in MySQL
          5.1; import the table again following the downgrade to MySQL
          5.0.

        * Prior to the downgrade, remove the table's partitioning using
          `ALTER TABLE TABLE_NAME REMOVE PARTITIONING'.

   * Stored routines

     MySQL 5.1.21 added a number of new columns to the `mysql.proc'
     table in which stored routine definitions are stored. If you are
     downgrading from MySQL 5.1.21 or later to MySQL 5.0, you cannot
     import the MySQL 5.1 routine definitions into MySQL 5.0.46 or
     earlier using the dump of `mysql.proc' created by `mysqldump'
     (such as when using the `--all-databases' option).  Instead, you
     should run `mysqldump `--routines'' prior to performing the
     downgrade and run the stored routines DDL statements following the
     downgrade.

     See Bug#11986 (http://bugs.mysql.com/11986), Bug#30029
     (http://bugs.mysql.com/30029), and Bug#30660
     (http://bugs.mysql.com/30660), for more information.


File: manual.info,  Node: operating-system-specific-notes,  Next: environment-variables,  Prev: downgrading,  Up: installing

2.13 Operating System-Specific Notes
====================================

* Menu:

* linux::                        Linux Notes
* mac-os-x::                     Mac OS X Notes
* solaris::                      Solaris Notes
* bsd-notes::                    BSD Notes
* other-unix-notes::             Other Unix Notes


File: manual.info,  Node: linux,  Next: mac-os-x,  Prev: operating-system-specific-notes,  Up: operating-system-specific-notes

2.13.1 Linux Notes
------------------

* Menu:

* linux-os::                     Linux Operating System Notes
* binary-notes-linux::           Linux Binary Distribution Notes
* source-notes-linux::           Linux Source Distribution Notes
* linux-post-install::           Linux Post-Installation Notes
* linux-x86::                    Linux x86 Notes
* linux-sparc::                  Linux SPARC Notes
* linux-alpha::                  Linux Alpha Notes
* linux-powerpc::                Linux PowerPC Notes
* linux-mips::                   Linux MIPS Notes
* linux-ia-64::                  Linux IA-64 Notes
* selinux::                      SELinux Notes

This section discusses issues that have been found to occur on Linux.
The first few subsections describe general operating system-related
issues, problems that can occur when using binary or source
distributions, and post-installation issues. The remaining subsections
discuss problems that occur with Linux on specific platforms.

Note that most of these problems occur on older versions of Linux. If
you are running a recent version, you may see none of them.


File: manual.info,  Node: linux-os,  Next: binary-notes-linux,  Prev: linux,  Up: linux

2.13.1.1 Linux Operating System Notes
.....................................

MySQL needs at least Linux version 2.0.

*Warning*:

We have seen some strange problems with Linux 2.2.14 and MySQL on SMP
systems. We also have reports from some MySQL users that they have
encountered serious stability problems using MySQL with kernel 2.2.14.
If you are using this kernel, you should upgrade to 2.2.19 (or newer)
or to a 2.4 kernel. If you have a multiple-CPU box, you should seriously
consider using 2.4 because it gives you a significant speed boost. Your
system should be more stable.

When using LinuxThreads, you should see a minimum of three `mysqld'
processes running. These are in fact threads. There is one thread for
the LinuxThreads manager, one thread to handle connections, and one
thread to handle alarms and signals.


File: manual.info,  Node: binary-notes-linux,  Next: source-notes-linux,  Prev: linux-os,  Up: linux

2.13.1.2 Linux Binary Distribution Notes
........................................

The Linux-Intel binary and RPM releases of MySQL are configured for the
highest possible speed. We are always trying to use the fastest stable
compiler available.

The binary release is linked with `-static', which means you do not
normally need to worry about which version of the system libraries you
have. You need not install LinuxThreads, either. A program linked with
`-static' is slightly larger than a dynamically linked program, but
also slightly faster (3-5%). However, one problem with a statically
linked program is that you can't use user-defined functions (UDFs). If
you are going to write or use UDFs (this is something for C or C++
programmers only), you must compile MySQL yourself using dynamic
linking.

A known issue with binary distributions is that on older Linux systems
that use `libc' (such as Red Hat 4.x or Slackware), you get some
(non-fatal) issues with hostname resolution. If your system uses `libc'
rather than `glibc2', you probably will encounter some difficulties
with hostname resolution and `getpwnam()'. This happens because `glibc'
(unfortunately) depends on some external libraries to implement
hostname resolution and `getpwent()', even when compiled with
`-static'. These problems manifest themselves in two ways:

   * You may see the following error message when you run
     `mysql_install_db':

          Sorry, the host 'XXXX' could not be looked up

     You can deal with this by executing `mysql_install_db --force',
     which does not execute the `resolveip' test in `mysql_install_db'.
     The downside is that you cannot use hostnames in the grant tables:
     except for `localhost', you must use IP numbers instead. If you
     are using an old version of MySQL that does not support `--force',
     you must manually remove the `resolveip' test in
     `mysql_install_db' using a text editor.

   * You also may see the following error when you try to run `mysqld'
     with the `--user' option:

          getpwnam: No such file or directory

     To work around this problem, start `mysqld' by using the `su'
     command rather than by specifying the `--user' option. This causes
     the system itself to change the user ID of the `mysqld' process so
     that `mysqld' need not do so.

Another solution, which solves both problems, is not to use a binary
distribution. Obtain a MySQL source distribution (in RPM or `tar.gz'
format) and install that instead.

On some Linux 2.2 versions, you may get the error `Resource temporarily
unavailable' when clients make a great many new connections to a
`mysqld' server over TCP/IP. The problem is that Linux has a delay
between the time that you close a TCP/IP socket and the time that the
system actually frees it.  There is room for only a finite number of
TCP/IP slots, so you encounter the resource-unavailable error if
clients attempt too many new TCP/IP connections over a short period of
time.  For example, you may see the error when you run the MySQL
`test-connect' benchmark over TCP/IP.

We have inquired about this problem a few times on different Linux
mailing lists but have never been able to find a suitable resolution.
The only known `fix' is for clients to use persistent connections, or,
if you are running the database server and clients on the same machine,
to use Unix socket file connections rather than TCP/IP connections.


File: manual.info,  Node: source-notes-linux,  Next: linux-post-install,  Prev: binary-notes-linux,  Up: linux

2.13.1.3 Linux Source Distribution Notes
........................................

The following notes regarding `glibc' apply only to the situation when
you build MySQL yourself. If you are running Linux on an x86 machine,
in most cases it is much better for you to use our binary. We link our
binaries against the best patched version of `glibc' we can find and
with the best compiler options, in an attempt to make it suitable for a
high-load server. For a typical user, even for setups with a lot of
concurrent connections or tables exceeding the 2GB limit, our binary is
the best choice in most cases. After reading the following text, if you
are in doubt about what to do, try our binary first to determine
whether it meets your needs. If you discover that it is not good enough,
you may want to try your own build. In that case, we would appreciate a
note about it so that we can build a better binary next time.

MySQL uses LinuxThreads on Linux. If you are using an old Linux version
that doesn't have `glibc2', you must install LinuxThreads before trying
to compile MySQL. You can obtain LinuxThreads from
`http://dev.mysql.com/downloads/os-linux.html'.

Note that `glibc' versions before and including version 2.1.1 have a
fatal bug in `pthread_mutex_timedwait()' handling, which is used when
`INSERT DELAYED' statements are issued. We recommend that you not use
`INSERT DELAYED' before upgrading `glibc'.

Note that Linux kernel and the LinuxThread library can by default
handle a maximum of 1,024 threads. If you plan to have more than 1,000
concurrent connections, you need to make some changes to LinuxThreads,
as follows:

   * Increase `PTHREAD_THREADS_MAX' in
     `sysdeps/unix/sysv/linux/bits/local_lim.h' to 4096 and decrease
     `STACK_SIZE' in `linuxthreads/internals.h' to 256KB.  The paths
     are relative to the root of `glibc'. (Note that MySQL is not stable
     with 600-1000 connections if `STACK_SIZE' is the default of 2MB.)

   * Recompile LinuxThreads to produce a new `libpthread.a' library,
     and relink MySQL against it.

There is another issue that greatly hurts MySQL performance, especially
on SMP systems. The mutex implementation in LinuxThreads in `glibc' 2.1
is very poor for programs with many threads that hold the mutex only
for a short time. This produces a paradoxical result: If you link MySQL
against an unmodified LinuxThreads, removing processors from an SMP
actually improves MySQL performance in many cases.  We have made a
patch available for `glibc' 2.1.3 to correct this behavior
(`http://dev.mysql.com/Downloads/Linux/linuxthreads-2.1-patch').

With `glibc' 2.2.2, MySQL uses the adaptive mutex, which is much better
than even the patched one in `glibc' 2.1.3. Be warned, however, that
under some conditions, the current mutex code in `glibc' 2.2.2
overspins, which hurts MySQL performance. The likelihood that this
condition occurs can be reduced by re-nicing the `mysqld' process to
the highest priority. We have also been able to correct the overspin
behavior with a patch, available at
`http://dev.mysql.com/Downloads/Linux/linuxthreads-2.2.2.patch'.  It
combines the correction of overspin, maximum number of threads, and
stack spacing all in one. You need to apply it in the `linuxthreads'
directory with `patch -p0 </tmp/linuxthreads-2.2.2.patch'. We hope it is
included in some form in future releases of `glibc' 2.2. In any case,
if you link against `glibc' 2.2.2, you still need to correct
`STACK_SIZE' and `PTHREAD_THREADS_MAX'. We hope that the defaults is
corrected to some more acceptable values for high-load MySQL setup in
the future, so that the commands needed to produce your own build can
be reduced to `./configure; make; make install'.

We recommend that you use these patches to build a special static
version of `libpthread.a' and use it only for statically linking
against MySQL. We know that these patches are safe for MySQL and
significantly improve its performance, but we cannot say anything about
their effects on other applications. If you link other applications that
require LinuxThreads against the patched static version of the library,
or build a patched shared version and install it on your system, you do
so at your own risk.

If you experience any strange problems during the installation of
MySQL, or with some common utilities hanging, it is very likely that
they are either library or compiler related. If this is the case, using
our binary resolves them.

If you link your own MySQL client programs, you may see the following
error at runtime:

     ld.so.1: fatal: libmysqlclient.so.#:
     open failed: No such file or directory

This problem can be avoided by one of the following methods:

   * Link clients with the `-Wl,r/full/path/to/libmysqlclient.so' flag
     rather than with `-Lpath').

   * Copy `libmysqclient.so' to `/usr/lib'.

   * Add the pathname of the directory where `libmysqlclient.so' is
     located to the `LD_RUN_PATH' environment variable before running
     your client.

If you are using the Fujitsu compiler (`fcc/FCC'), you may have some
problems compiling MySQL because the Linux header files are very `gcc'
oriented. The following `configure' line should work with `fcc/FCC':

     CC=fcc CFLAGS="-O -K fast -K lib -K omitfp -Kpreex -D_GNU_SOURCE \
         -DCONST=const -DNO_STRTOLL_PROTO" \
     CXX=FCC CXXFLAGS="-O -K fast -K lib \
         -K omitfp -K preex --no_exceptions --no_rtti -D_GNU_SOURCE \
         -DCONST=const -Dalloca=__builtin_alloca -DNO_STRTOLL_PROTO \
         '-D_EXTERN_INLINE=static __inline'" \
     ./configure \
         --prefix=/usr/local/mysql --enable-assembler \
         --with-mysqld-ldflags=-all-static --disable-shared \
         --with-low-memory


File: manual.info,  Node: linux-post-install,  Next: linux-x86,  Prev: source-notes-linux,  Up: linux

2.13.1.4 Linux Post-Installation Notes
......................................

`mysql.server' can be found in the `support-files' directory under the
MySQL installation directory or in a MySQL source tree. You can install
it as `/etc/init.d/mysql' for automatic MySQL startup and shutdown. See
*Note automatic-start::.

If MySQL cannot open enough files or connections, it may be that you
have not configured Linux to handle enough files.

In Linux 2.2 and onward, you can check the number of allocated file
handles as follows:

     shell> cat /proc/sys/fs/file-max
     shell> cat /proc/sys/fs/dquot-max
     shell> cat /proc/sys/fs/super-max

If you have more than 16MB of memory, you should add something like the
following to your init scripts (for example, `/etc/init.d/boot.local'
on SuSE Linux):

     echo 65536 > /proc/sys/fs/file-max
     echo 8192 > /proc/sys/fs/dquot-max
     echo 1024 > /proc/sys/fs/super-max

You can also run the `echo' commands from the command line as `root',
but these settings are lost the next time your computer restarts.

Alternatively, you can set these parameters on startup by using the
`sysctl' tool, which is used by many Linux distributions (including
SuSE Linux 8.0 and later).  Put the following values into a file named
`/etc/sysctl.conf':

     # Increase some values for MySQL
     fs.file-max = 65536
     fs.dquot-max = 8192
     fs.super-max = 1024

You should also add the following to `/etc/my.cnf':

     [mysqld_safe]
     open-files-limit=8192

This should allow the server a limit of 8,192 for the combined number
of connections and open files.

The `STACK_SIZE' constant in LinuxThreads controls the spacing of
thread stacks in the address space. It needs to be large enough so that
there is plenty of room for each individual thread stack, but small
enough to keep the stack of some threads from running into the global
`mysqld' data. Unfortunately, as we have experimentally discovered, the
Linux implementation of `mmap()' successfully unmaps a mapped region if
you ask it to map out an address currently in use, zeroing out the data
on the entire page instead of returning an error.  So, the safety of
`mysqld' or any other threaded application depends on the `gentlemanly'
behavior of the code that creates threads. The user must take measures
to make sure that the number of running threads at any given time is
sufficiently low for thread stacks to stay away from the global heap.
With `mysqld', you should enforce this behavior by setting a reasonable
value for the `max_connections' variable.

If you build MySQL yourself, you can patch LinuxThreads for better
stack use. See *Note source-notes-linux::. If you do not want to patch
LinuxThreads, you should set `max_connections' to a value no higher than
500. It should be even less if you have a large key buffer, large heap
tables, or some other things that make `mysqld' allocate a lot of
memory, or if you are running a 2.2 kernel with a 2GB patch. If you are
using our binary or RPM version, you can safely set `max_connections'
at 1500, assuming no large key buffer or heap tables with lots of data.
The more you reduce `STACK_SIZE' in LinuxThreads the more threads you
can safely create. We recommend values between 128KB and 256KB.

If you use a lot of concurrent connections, you may suffer from a
`feature' in the 2.2 kernel that attempts to prevent fork bomb attacks
by penalizing a process for forking or cloning a child. This causes
MySQL not to scale well as you increase the number of concurrent
clients. On single-CPU systems, we have seen this manifest as very slow
thread creation; it may take a long time to connect to MySQL (as long
as one minute), and it may take just as long to shut it down. On
multiple-CPU systems, we have observed a gradual drop in query speed as
the number of clients increases. In the process of trying to find a
solution, we have received a kernel patch from one of our users who
claimed it helped for his site. This patch is available at
`http://dev.mysql.com/Downloads/Patches/linux-fork.patch'.  We have
done rather extensive testing of this patch on both development and
production systems. It has significantly improved MySQL performance
without causing any problems and we recommend it to our users who still
run high-load servers on 2.2 kernels.

This issue has been fixed in the 2.4 kernel, so if you are not
satisfied with the current performance of your system, rather than
patching your 2.2 kernel, it might be easier to upgrade to 2.4. On SMP
systems, upgrading also gives you a nice SMP boost in addition to
fixing the fairness bug.

We have tested MySQL on the 2.4 kernel on a two-CPU machine and found
MySQL scales _much_ better. There was virtually no slowdown on query
throughput all the way up to 1,000 clients, and the MySQL scaling
factor (computed as the ratio of maximum throughput to the throughput
for one client) was 180%. We have observed similar results on a
four-CPU system: Virtually no slowdown as the number of clients was
increased up to 1,000, and a 300% scaling factor.  Based on these
results, for a high-load SMP server using a 2.2 kernel, we definitely
recommend upgrading to the 2.4 kernel at this point.

We have discovered that it is essential to run the `mysqld' process
with the highest possible priority on the 2.4 kernel to achieve maximum
performance.  This can be done by adding a `renice -20 $$' command to
`mysqld_safe'. In our testing on a four-CPU machine, increasing the
priority resulted in a 60% throughput increase with 400 clients.

We are currently also trying to collect more information on how well
MySQL performs with a 2.4 kernel on four-way and eight-way systems. If
you have access such a system and have done some benchmarks, please
send an email message to <benchmarks@mysql.com> with the results. We
will review them for inclusion in the manual.

If you see a dead `mysqld' server process with `ps', this usually means
that you have found a bug in MySQL or you have a corrupted table. See
*Note crashing::.

To get a core dump on Linux if `mysqld' dies with a `SIGSEGV' signal,
you can start `mysqld' with the `--core-file' option. Note that you also
probably need to raise the core file size by adding `ulimit -c 1000000'
to `mysqld_safe' or starting `mysqld_safe' with
`--core-file-size=1000000'. See *Note mysqld-safe::.


File: manual.info,  Node: linux-x86,  Next: linux-sparc,  Prev: linux-post-install,  Up: linux

2.13.1.5 Linux x86 Notes
........................

MySQL requires `libc' 5.4.12 or newer. It is known to work with `libc'
5.4.46.  `glibc' 2.0.6 and later should also work.  There have been
some problems with the `glibc' RPMs from Red Hat, so if you have
problems, check whether there are any updates. The `glibc' 2.0.7-19 and
2.0.7-29 RPMs are known to work.

If you are using Red Hat 8.0 or a new `glibc' 2.2.x library, you may
see `mysqld' die in `gethostbyaddr()'. This happens because the new
`glibc' library requires a stack size greater than 128KB for this call.
To fix the problem, start `mysqld' with the `--thread-stack=192K'
option. (Use `-O thread_stack=192K' before MySQL 4.) This stack size is
the default on MySQL 4.0.10 and above, so you should not see the
problem.

If you are using `gcc' 3.0 and above to compile MySQL, you must install
the `libstdc++v3' library before compiling MySQL; if you don't do this,
you get an error about a missing `__cxa_pure_virtual' symbol during
linking.

On some older Linux distributions, `configure' may produce an error
like this:

     Syntax error in sched.h. Change _P to __P in the
     /usr/include/sched.h file.
     See the Installation chapter in the Reference Manual.

Just do what the error message says. Add an extra underscore to the
`_P' macro name that has only one underscore, and then try again.

You may get some warnings when compiling. Those shown here can be
ignored:

     mysqld.cc -o objs-thread/mysqld.o
     mysqld.cc: In function `void init_signals()':
     mysqld.cc:315: warning: assignment of negative value `-1' to
     `long unsigned int'
     mysqld.cc: In function `void * signal_hand(void *)':
     mysqld.cc:346: warning: assignment of negative value `-1' to
     `long unsigned int'

If `mysqld' always dumps core when it starts, the problem may be that
you have an old `/lib/libc.a'. Try renaming it, and then remove
`sql/mysqld' and do a new `make install' and try again. This problem
has been reported on some Slackware installations.

If you get the following error when linking `mysqld', it means that your
`libg++.a' is not installed correctly:

     /usr/lib/libc.a(putc.o): In function `_IO_putc':
     putc.o(.text+0x0): multiple definition of `_IO_putc'

You can avoid using `libg++.a' by running `configure' like this:

     shell> CXX=gcc ./configure


File: manual.info,  Node: linux-sparc,  Next: linux-alpha,  Prev: linux-x86,  Up: linux

2.13.1.6 Linux SPARC Notes
..........................

In some implementations, `readdir_r()' is broken. The symptom is that
the `SHOW DATABASES' statement always returns an empty set.  This can
be fixed by removing `HAVE_READDIR_R' from `config.h' after configuring
and before compiling.


File: manual.info,  Node: linux-alpha,  Next: linux-powerpc,  Prev: linux-sparc,  Up: linux

2.13.1.7 Linux Alpha Notes
..........................

We have tested MySQL 5.1 on Alpha with our benchmarks and test suite,
and it appears to work well.

We currently build the MySQL binary packages on SuSE Linux 7.0 for AXP,
kernel 2.4.4-SMP, Compaq C compiler (V6.2-505) and Compaq C++ compiler
(V6.3-006) on a Compaq DS20 machine with an Alpha EV6 processor.

You can find the preceding compilers at
`http://www.support.compaq.com/alpha-tools/'. By using these compilers
rather than `gcc', we get about 9-14% better MySQL performance.

For MySQL on Alpha, we use the `-arch generic' flag to our compile
options, which ensures that the binary runs on all Alpha processors. We
also compile statically to avoid library problems. The `configure'
command looks like this:

     CC=ccc CFLAGS="-fast -arch generic" CXX=cxx \
     CXXFLAGS="-fast -arch generic -noexceptions -nortti" \
     ./configure --prefix=/usr/local/mysql --disable-shared \
         --with-extra-charsets=complex --enable-thread-safe-client \
         --with-mysqld-ldflags=-non_shared --with-client-ldflags=-non_shared

Some known problems when running MySQL on Linux-Alpha:

   * Debugging threaded applications like MySQL does not work with `gdb
     4.18'. You should use `gdb' 5.1 instead.

   * If you try linking `mysqld' statically when using `gcc', the
     resulting image dumps core at startup time. In other words, _do
     not_ use `--with-mysqld-ldflags=-all-static' with `gcc'.


File: manual.info,  Node: linux-powerpc,  Next: linux-mips,  Prev: linux-alpha,  Up: linux

2.13.1.8 Linux PowerPC Notes
............................

MySQL should work on MkLinux with the newest `glibc' package (tested
with `glibc' 2.0.7).


File: manual.info,  Node: linux-mips,  Next: linux-ia-64,  Prev: linux-powerpc,  Up: linux

2.13.1.9 Linux MIPS Notes
.........................

To get MySQL to work on Qube2 (Linux Mips), you need the newest `glibc'
libraries.  `glibc-2.0.7-29C2' is known to work. You must also use
`gcc' 2.95.2 or newer).


File: manual.info,  Node: linux-ia-64,  Next: selinux,  Prev: linux-mips,  Up: linux

2.13.1.10 Linux IA-64 Notes
...........................

To get MySQL to compile on Linux IA-64, we use the following
`configure' command for building with `gcc' 2.96:

     CC=gcc \
     CFLAGS="-O3 -fno-omit-frame-pointer" \
     CXX=gcc \
     CXXFLAGS="-O3 -fno-omit-frame-pointer -felide-constructors \
         -fno-exceptions -fno-rtti" \
         ./configure --prefix=/usr/local/mysql \
         "--with-comment=Official MySQL binary" \
         --with-extra-charsets=complex

On IA-64, the MySQL client binaries use shared libraries. This means
that if you install our binary distribution at a location other than
`/usr/local/mysql', you need to add the path of the directory where you
have `libmysqlclient.so' installed either to the `/etc/ld.so.conf' file
or to the value of your `LD_LIBRARY_PATH' environment variable.

See *Note link-errors::.


File: manual.info,  Node: selinux,  Prev: linux-ia-64,  Up: linux

2.13.1.11 SELinux Notes
.......................

RHEL4 comes with SELinux, which supports tighter access control for
processes. If SELinux is enabled (`SELINUX' in `/etc/selinux/config' is
set to `enforcing', `SELINUXTYPE' is set to either `targeted' or
`strict'), you might encounter problems installing MySQL AB RPM
packages.

Red Hat has an update that solves this. It involves an update of the
`security policy' specification to handle the install structure of the
RPMs provided by MySQL AB. For further information, see
`https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=167551' and
`http://rhn.redhat.com/errata/RHBA-2006-0049.html'.

The preceding discussion applies only to RHEL4. The patch is
unnecessary for RHEL5.


File: manual.info,  Node: mac-os-x,  Next: solaris,  Prev: linux,  Up: operating-system-specific-notes

2.13.2 Mac OS X Notes
---------------------

* Menu:

* mac-os-x-10-x::                Mac OS X 10.x (Darwin)
* mac-os-x-server::              Mac OS X Server 1.2 (Rhapsody)

On Mac OS X, `tar' cannot handle long filenames. If you need to unpack
a `.tar.gz' distribution, use `gnutar' instead.


File: manual.info,  Node: mac-os-x-10-x,  Next: mac-os-x-server,  Prev: mac-os-x,  Up: mac-os-x

2.13.2.1 Mac OS X 10.x (Darwin)
...............................

MySQL should work without major problems on Mac OS X 10.x (Darwin).

Known issues:

   * If you have problems with performance under heavy load, try using
     the `--skip-thread-priority' option to `mysqld'. This runs all
     threads with the same priority. On Mac OS X, this gives better
     performance, at least until Apple fixes its thread scheduler.

   * The connection times (`wait_timeout', `interactive_timeout' and
     `net_read_timeout') values are not honored.

     This is probably a signal handling problem in the thread library
     where the signal doesn't break a pending read and we hope that a
     future update to the thread libraries will fix this.

Our binary for Mac OS X is compiled on Darwin 6.3 with the following
`configure' line:

     CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc \
     CXXFLAGS="-O3 -fno-omit-frame-pointer -felide-constructors \
         -fno-exceptions -fno-rtti" \
         ./configure --prefix=/usr/local/mysql \
         --with-extra-charsets=complex --enable-thread-safe-client \
         --enable-local-infile --disable-shared

See *Note mac-os-x-installation::.


File: manual.info,  Node: mac-os-x-server,  Prev: mac-os-x-10-x,  Up: mac-os-x

2.13.2.2 Mac OS X Server 1.2 (Rhapsody)
.......................................

For current versions of Mac OS X Server, no operating system changes
are necessary before compiling MySQL. Compiling for the Server platform
is the same as for the client version of Mac OS X.

For older versions (Mac OS X Server 1.2, a.k.a. Rhapsody), you must
first install a pthread package before trying to configure MySQL.

See *Note mac-os-x-installation::.


File: manual.info,  Node: solaris,  Next: bsd-notes,  Prev: mac-os-x,  Up: operating-system-specific-notes

2.13.3 Solaris Notes
--------------------

* Menu:

* solaris-2-7::                  Solaris 2.7/2.8 Notes
* solaris-x86::                  Solaris x86 Notes

For information about installing MySQL on Solaris using PKG
distributions, see *Note solaris-installation::.

On Solaris, you may run into trouble even before you get the MySQL
distribution unpacked, as the Solaris `tar' cannot handle long
filenames. This means that you may see errors when you try to unpack
MySQL.

If this occurs, you must use GNU `tar' (`gtar') to unpack the
distribution. You can find a precompiled copy for Solaris at
`http://dev.mysql.com/downloads/os-solaris.html'.

Sun native threads work only on Solaris 2.5 and higher. For Solaris 2.4
and earlier, MySQL automatically uses MIT-pthreads.  See *Note
mit-pthreads::.

If you get the following error from `configure', it means that you have
something wrong with your compiler installation:

     checking for restartable system calls... configure: error can not
     run test programs while cross compiling

In this case, you should upgrade your compiler to a newer version. You
may also be able to solve this problem by inserting the following row
into the `config.cache' file:

     ac_cv_sys_restartable_syscalls=${ac_cv_sys_restartable_syscalls='no'}

If you are using Solaris on a SPARC, the recommended compiler is `gcc'
2.95.2 or 3.2. You can find this at `http://gcc.gnu.org/'. Note that
`gcc' 2.8.1 does not work reliably on SPARC.

The recommended `configure' line when using `gcc' 2.95.2 is:

     CC=gcc CFLAGS="-O3" \
     CXX=gcc CXXFLAGS="-O3 -felide-constructors -fno-exceptions -fno-rtti" \
     ./configure --prefix=/usr/local/mysql --with-low-memory \
         --enable-assembler

If you have an UltraSPARC system, you can get 4% better performance by
adding `-mcpu=v8 -Wa,-xarch=v8plusa' to the `CFLAGS' and `CXXFLAGS'
environment variables.

If you have Sun's Forte 5.0 (or newer) compiler, you can run
`configure' like this:

     CC=cc CFLAGS="-Xa -fast -native -xstrconst -mt" \
     CXX=CC CXXFLAGS="-noex -mt" \
     ./configure --prefix=/usr/local/mysql --enable-assembler

To create a 64-bit binary with Sun's Forte compiler, use the following
configuration options:

     CC=cc CFLAGS="-Xa -fast -native -xstrconst -mt -xarch=v9" \
     CXX=CC CXXFLAGS="-noex -mt -xarch=v9" ASFLAGS="-xarch=v9" \
     ./configure --prefix=/usr/local/mysql --enable-assembler

To create a 64-bit Solaris binary using `gcc', add `-m64' to `CFLAGS'
and `CXXFLAGS' and remove `--enable-assembler' from the `configure'
line.

In the MySQL benchmarks, we obtained a 4% speed increase on UltraSPARC
when using Forte 5.0 in 32-bit mode, as compared to using `gcc' 3.2
with the `-mcpu' flag.

If you create a 64-bit `mysqld' binary, it is 4% slower than the 32-bit
binary, but can handle more threads and memory.

When using Solaris 10 for x86_64, you should mount any filesystems on
which you intend to store `InnoDB' files with the `forcedirectio'
option. (By default mounting is done without this option.) Failing to
do so will cause a significant drop in performance when using the
`InnoDB' storage engine on this platform.

If you get a problem with `fdatasync' or `sched_yield', you can fix
this by adding `LIBS=-lrt' to the `configure' line

For compilers older than WorkShop 5.3, you might have to edit the
`configure' script. Change this line:

     #if !defined(__STDC__) || __STDC__ != 1

To this:

     #if !defined(__STDC__)

If you turn on `__STDC__' with the `-Xc' option, the Sun compiler can't
compile with the Solaris `pthread.h' header file. This is a Sun bug
(broken compiler or broken include file).

If `mysqld' issues the following error message when you run it, you
have tried to compile MySQL with the Sun compiler without enabling the
`-mt' multi-thread option:

     libc internal error: _rmutex_unlock: rmutex not held

Add `-mt' to `CFLAGS' and `CXXFLAGS' and recompile.

If you are using the SFW version of `gcc' (which comes with Solaris 8),
you must add `/opt/sfw/lib' to the environment variable
`LD_LIBRARY_PATH' before running `configure'.

If you are using the `gcc' available from `sunfreeware.com', you may
have many problems.  To avoid this, you should recompile `gcc' and GNU
`binutils' on the machine where you are running them.

If you get the following error when compiling MySQL with `gcc', it
means that your `gcc' is not configured for your version of Solaris:

     shell> gcc -O3 -g -O2 -DDBUG_OFF  -o thr_alarm ...
     ./thr_alarm.c: In function `signal_hand':
     ./thr_alarm.c:556: too many arguments to function `sigwait'

The proper thing to do in this case is to get the newest version of
`gcc' and compile it with your current `gcc' compiler. At least for
Solaris 2.5, almost all binary versions of `gcc' have old, unusable
include files that break all programs that use threads, and possibly
other programs as well.

Solaris does not provide static versions of all system libraries
(`libpthreads' and `libdl'), so you cannot compile MySQL with
`--static'. If you try to do so, you get one of the following errors:

     ld: fatal: library -ldl: not found
     undefined reference to `dlopen'
     cannot find -lrt

If you link your own MySQL client programs, you may see the following
error at runtime:

     ld.so.1: fatal: libmysqlclient.so.#:
     open failed: No such file or directory

This problem can be avoided by one of the following methods:

   * Link clients with the `-Wl,r/full/path/to/libmysqlclient.so' flag
     rather than with `-Lpath').

   * Copy `libmysqclient.so' to `/usr/lib'.

   * Add the pathname of the directory where `libmysqlclient.so' is
     located to the `LD_RUN_PATH' environment variable before running
     your client.

If you have problems with `configure' trying to link with `-lz' when
you don't have `zlib' installed, you have two options:

   * If you want to be able to use the compressed communication
     protocol, you need to get and install `zlib' from `ftp.gnu.org'.

   * Run `configure' with the `--with-named-z-libs=no' option when
     building MySQL.

If you are using `gcc' and have problems with loading user-defined
functions (UDFs) into MySQL, try adding `-lgcc' to the link line for
the UDF.

If you would like MySQL to start automatically, you can copy
`support-files/mysql.server' to `/etc/init.d' and create a symbolic
link to it named `/etc/rc3.d/S99mysql.server'.

If too many processes try to connect very rapidly to `mysqld', you
should see this error in the MySQL log:

     Error in accept: Protocol error

You might try starting the server with the `--back_log=50' option as a
workaround for this.  (Use `-O back_log=50' before MySQL 4.)

Solaris doesn't support core files for `setuid()' applications, so you
can't get a core file from `mysqld' if you are using the `--user'
option.


File: manual.info,  Node: solaris-2-7,  Next: solaris-x86,  Prev: solaris,  Up: solaris

2.13.3.1 Solaris 2.7/2.8 Notes
..............................

Normally, you can use a Solaris 2.6 binary on Solaris 2.7 and 2.8. Most
of the Solaris 2.6 issues also apply for Solaris 2.7 and 2.8.

MySQL should be able to detect new versions of Solaris automatically
and enable workarounds for the following problems.

Solaris 2.7 / 2.8 has some bugs in the include files. You may see the
following error when you use `gcc':

     /usr/include/widec.h:42: warning: `getwc' redefined
     /usr/include/wchar.h:326: warning: this is the location of the previous
     definition

If this occurs, you can fix the problem by copying
`/usr/include/widec.h' to `.../lib/gcc-lib/os/gcc-version/include' and
changing line 41 from this:

     #if     !defined(lint) && !defined(__lint)

To this:

     #if     !defined(lint) && !defined(__lint) && !defined(getwc)

Alternatively, you can edit `/usr/include/widec.h' directly. Either
way, after you make the fix, you should remove `config.cache' and run
`configure' again.

If you get the following errors when you run `make', it's because
`configure' didn't detect the `curses.h' file (probably because of the
error in `/usr/include/widec.h'):

     In file included from mysql.cc:50:
     /usr/include/term.h:1060: syntax error before `,'
     /usr/include/term.h:1081: syntax error before `;'

The solution to this problem is to do one of the following:

   * Configure with `CFLAGS=-DHAVE_CURSES_H CXXFLAGS=-DHAVE_CURSES_H
     ./configure'.

   * Edit `/usr/include/widec.h' as indicated in the preceding
     discussion and re-run `configure'.

   * Remove the `#define HAVE_TERM' line from the `config.h' file and
     run `make' again.

If your linker cannot find `-lz' when linking client programs, the
problem is probably that your `libz.so' file is installed in
`/usr/local/lib'. You can fix this problem by one of the following
methods:

   * Add `/usr/local/lib' to `LD_LIBRARY_PATH'.

   * Add a link to `libz.so' from `/lib'.

   * If you are using Solaris 8, you can install the optional `zlib'
     from your Solaris 8 CD distribution.

   * Run `configure' with the `--with-named-z-libs=no' option when
     building MySQL.


File: manual.info,  Node: solaris-x86,  Prev: solaris-2-7,  Up: solaris

2.13.3.2 Solaris x86 Notes
..........................

On Solaris 8 on x86, `mysqld' dumps core if you remove the debug
symbols using `strip'.

If you are using `gcc' on Solaris x86 and you experience problems with
core dumps under load, you should use the following `configure' command:

     CC=gcc CFLAGS="-O3 -fomit-frame-pointer -DHAVE_CURSES_H" \
     CXX=gcc \
     CXXFLAGS="-O3 -fomit-frame-pointer -felide-constructors \
         -fno-exceptions -fno-rtti -DHAVE_CURSES_H" \
     ./configure --prefix=/usr/local/mysql

This avoids problems with the `libstdc++' library and with C++
exceptions.

If this doesn't help, you should compile a debug version and run it
with a trace file or under `gdb'. See MySQL Internals: Porting
(http://forge.mysql.com/wiki/MySQL_Internals_Porting).


File: manual.info,  Node: bsd-notes,  Next: other-unix-notes,  Prev: solaris,  Up: operating-system-specific-notes

2.13.4 BSD Notes
----------------

* Menu:

* freebsd::                      FreeBSD Notes
* netbsd::                       NetBSD Notes
* openbsd::                      OpenBSD 2.5 Notes
* bsdi::                         BSD/OS Version 2.x Notes
* bsdi3::                        BSD/OS Version 3.x Notes
* bsdi4::                        BSD/OS Version 4.x Notes

This section provides information about using MySQL on variants of BSD
Unix.


File: manual.info,  Node: freebsd,  Next: netbsd,  Prev: bsd-notes,  Up: bsd-notes

2.13.4.1 FreeBSD Notes
......................

FreeBSD 4.x or newer is recommended for running MySQL, because the
thread package is much more integrated. To get a secure and stable
system, you should use only FreeBSD kernels that are marked `-RELEASE'.

The easiest (and preferred) way to install MySQL is to use the
`mysql-server' and `mysql-client' ports available at
`http://www.freebsd.org/'. Using these ports gives you the following
benefits:

   * A working MySQL with all optimizations enabled that are known to
     work on your version of FreeBSD.

   * Automatic configuration and build.

   * Startup scripts installed in `/usr/local/etc/rc.d'.

   * The ability to use `pkg_info -L' to see which files are installed.

   * The ability to use `pkg_delete' to remove MySQL if you no longer
     want it on your machine.

It is recommended you use MIT-pthreads on FreeBSD 2.x, and native
threads on FreeBSD 3 and up. It is possible to run with native threads
on some late 2.2.x versions, but you may encounter problems shutting
down `mysqld'.

Unfortunately, certain function calls on FreeBSD are not yet fully
thread-safe. Most notably, this includes the `gethostbyname()'
function, which is used by MySQL to convert hostnames into IP
addresses. Under certain circumstances, the `mysqld' process suddenly
causes 100% CPU load and is unresponsive. If you encounter this
problem, try to start MySQL using the `--skip-name-resolve' option.

Alternatively, you can link MySQL on FreeBSD 4.x against the
LinuxThreads library, which avoids a few of the problems that the
native FreeBSD thread implementation has. For a very good comparison of
LinuxThreads versus native threads, see Jeremy Zawodny's article
`FreeBSD or Linux for your MySQL Server?' at
`http://jeremy.zawodny.com/blog/archives/000697.html'.

Known problem when using LinuxThreads on FreeBSD is:

   * The connection times (`wait_timeout', `interactive_timeout' and
     `net_read_timeout') values are not honored. The symptom is that
     persistent connections can hang for a very long time without
     getting closed down and that a 'kill' for a thread will not take
     affect until the thread does it a new command

     This is probably a signal handling problem in the thread library
     where the signal doesn't break a pending read.  This is supposed
     to be fixed in FreeBSD 5.0

The MySQL build process requires GNU make (`gmake') to work. If GNU
`make' is not available, you must install it first before compiling
MySQL.

The recommended way to compile and install MySQL on FreeBSD with `gcc'
(2.95.2 and up) is:

     CC=gcc CFLAGS="-O2 -fno-strength-reduce" \
         CXX=gcc CXXFLAGS="-O2 -fno-rtti -fno-exceptions \
         -felide-constructors -fno-strength-reduce" \
         ./configure --prefix=/usr/local/mysql --enable-assembler
     gmake
     gmake install
     cd /usr/local/mysql
     bin/mysql_install_db --user=mysql
     bin/mysqld_safe &

If you notice that `configure' uses MIT-pthreads, you should read the
MIT-pthreads notes. See *Note mit-pthreads::.

If you get an error from `make install' that it can't find
`/usr/include/pthreads', `configure' didn't detect that you need
MIT-pthreads. To fix this problem, remove `config.cache', and then
re-run `configure' with the `--with-mit-threads' option.

Be sure that your name resolver setup is correct. Otherwise, you may
experience resolver delays or failures when connecting to `mysqld'.
Also make sure that the `localhost' entry in the `/etc/hosts' file is
correct. The file should start with a line similar to this:

     127.0.0.1       localhost localhost.your.domain

FreeBSD is known to have a very low default file handle limit.  See
*Note not-enough-file-handles::. Start the server by using the
`--open-files-limit' option for `mysqld_safe', or raise the limits for
the `mysqld' user in `/etc/login.conf' and rebuild it with `cap_mkdb
/etc/login.conf'. Also be sure that you set the appropriate class for
this user in the password file if you are not using the default (use
`chpass mysqld-user-name'). See *Note mysqld-safe::.

FreeBSD limits the size of a process to 512MB, even if you have much
more RAM available on the system. So you may get an error such as this:

     Out of memory (Needed 16391 bytes)

In current versions of FreeBSD (at least 4.x and greater), you may
increase this limit by adding the following entries to the
`/boot/loader.conf' file and rebooting the machine (these are not
settings that can be changed at run time with the `sysctl' command):

     kern.maxdsiz="1073741824" # 1GB
     kern.dfldsiz="1073741824" # 1GB
     kern.maxssiz="134217728" # 128MB

For older versions of FreeBSD, you must recompile your kernel to change
the maximum data segment size for a process. In this case, you should
look at the `MAXDSIZ' option in the `LINT' config file for more
information.

If you get problems with the current date in MySQL, setting the `TZ'
variable should help. See *Note environment-variables::.


File: manual.info,  Node: netbsd,  Next: openbsd,  Prev: freebsd,  Up: bsd-notes

2.13.4.2 NetBSD Notes
.....................

To compile on NetBSD, you need GNU `make'.  Otherwise, the build
process fails when `make' tries to run `lint' on C++ files.


File: manual.info,  Node: openbsd,  Next: bsdi,  Prev: netbsd,  Up: bsd-notes

2.13.4.3 OpenBSD 2.5 Notes
..........................

On OpenBSD 2.5, you can compile MySQL with native threads with the
following options:

     CFLAGS=-pthread CXXFLAGS=-pthread ./configure --with-mit-threads=no


File: manual.info,  Node: bsdi,  Next: bsdi3,  Prev: openbsd,  Up: bsd-notes

2.13.4.4 BSD/OS Version 2.x Notes
.................................

If you get the following error when compiling MySQL, your `ulimit'
value for virtual memory is too low:

     item_func.h: In method
     `Item_func_ge::Item_func_ge(const Item_func_ge &)':
     item_func.h:28: virtual memory exhausted
     make[2]: *** [item_func.o] Error 1

Try using `ulimit -v 80000' and run `make' again. If this doesn't work
and you are using `bash', try switching to `csh' or `sh'; some BSDI
users have reported problems with `bash' and `ulimit'.

If you are using `gcc', you may also use have to use the
`--with-low-memory' flag for `configure' to be able to compile
`sql_yacc.cc'.

If you get problems with the current date in MySQL, setting the `TZ'
variable should help. See *Note environment-variables::.


File: manual.info,  Node: bsdi3,  Next: bsdi4,  Prev: bsdi,  Up: bsd-notes

2.13.4.5 BSD/OS Version 3.x Notes
.................................

Upgrade to BSD/OS 3.1. If that is not possible, install BSDIpatch
M300-038.

Use the following command when configuring MySQL:

     env CXX=shlicc++ CC=shlicc2 \
     ./configure \
         --prefix=/usr/local/mysql \
         --localstatedir=/var/mysql \
         --without-perl \
         --with-unix-socket-path=/var/mysql/mysql.sock

The following is also known to work:

     env CC=gcc CXX=gcc CXXFLAGS=-O3 \
     ./configure \
         --prefix=/usr/local/mysql \
         --with-unix-socket-path=/var/mysql/mysql.sock

You can change the directory locations if you wish, or just use the
defaults by not specifying any locations.

If you have problems with performance under heavy load, try using the
`--skip-thread-priority' option to `mysqld'. This runs all threads with
the same priority. On BSDI 3.1, this gives better performance, at least
until BSDI fixes its thread scheduler.

If you get the error `virtual memory exhausted' while compiling, you
should try using `ulimit -v 80000' and running `make' again. If this
doesn't work and you are using `bash', try switching to `csh' or `sh';
some BSDI users have reported problems with `bash' and `ulimit'.


File: manual.info,  Node: bsdi4,  Prev: bsdi3,  Up: bsd-notes

2.13.4.6 BSD/OS Version 4.x Notes
.................................

BSDI 4.x has some thread-related bugs. If you want to use MySQL on
this, you should install all thread-related patches.  At least M400-023
should be installed.

On some BSDI 4.x systems, you may get problems with shared libraries.
The symptom is that you can't execute any client programs, for example,
`mysqladmin'. In this case, you need to reconfigure not to use shared
libraries with the `--disable-shared' option to configure.

Some customers have had problems on BSDI 4.0.1 that the `mysqld' binary
after a while can't open tables. This occurs because some
library/system-related bug causes `mysqld' to change current directory
without having asked for that to happen.

The fix is to either upgrade MySQL to at least version 3.23.34 or,
after running `configure', remove the line `#define HAVE_REALPATH' from
`config.h' before running `make'.

Note that this means that you can't symbolically link a database
directories to another database directory or symbolic link a table to
another database on BSDI. (Making a symbolic link to another disk is
okay).


File: manual.info,  Node: other-unix-notes,  Prev: bsd-notes,  Up: operating-system-specific-notes

2.13.5 Other Unix Notes
-----------------------

* Menu:

* hp-ux-10-20::                  HP-UX Version 10.20 Notes
* hp-ux-11-x::                   HP-UX Version 11.x Notes
* ibm-aix::                      IBM-AIX notes
* sunos::                        SunOS 4 Notes
* alpha-dec-unix::               Alpha-DEC-UNIX Notes (Tru64)
* alpha-dec-osf1::               Alpha-DEC-OSF/1 Notes
* sgi-irix::                     SGI Irix Notes
* sco::                          SCO UNIX and OpenServer 5.0.x Notes
* sco-openserver::               SCO OpenServer 6.0.x Notes
* sco-unixware::                 SCO UnixWare 7.1.x and OpenUNIX 8.0.0 Notes


File: manual.info,  Node: hp-ux-10-20,  Next: hp-ux-11-x,  Prev: other-unix-notes,  Up: other-unix-notes

2.13.5.1 HP-UX Version 10.20 Notes
..................................

If you install MySQL using a binary tarball distribution on HP-UX, you
may run into trouble even before you get the MySQL distribution
unpacked, as the HP-UX `tar' cannot handle long filenames. This means
that you may see errors when you try to unpack MySQL.

If this occurs, you must use GNU `tar' (`gtar') to unpack the
distribution.

There are a couple of small problems when compiling MySQL on HP-UX. We
recommend that you use `gcc' instead of the HP-UX native compiler,
because `gcc' produces better code.

We recommend using `gcc' 2.95 on HP-UX. Don't use high optimization
flags (such as `-O6') because they may not be safe on HP-UX.

The following `configure' line should work with `gcc' 2.95:

     CFLAGS="-I/opt/dce/include -fpic" \
     CXXFLAGS="-I/opt/dce/include -felide-constructors -fno-exceptions \
     -fno-rtti" \
     CXX=gcc \
     ./configure --with-pthread \
         --with-named-thread-libs='-ldce' \
         --prefix=/usr/local/mysql --disable-shared

The following `configure' line should work with `gcc' 3.1:

     CFLAGS="-DHPUX -I/opt/dce/include -O3 -fPIC" CXX=gcc \
     CXXFLAGS="-DHPUX -I/opt/dce/include -felide-constructors \
         -fno-exceptions -fno-rtti -O3 -fPIC" \
     ./configure --prefix=/usr/local/mysql \
         --with-extra-charsets=complex --enable-thread-safe-client \
         --enable-local-infile  --with-pthread \
         --with-named-thread-libs=-ldce --with-lib-ccflags=-fPIC
         --disable-shared


File: manual.info,  Node: hp-ux-11-x,  Next: ibm-aix,  Prev: hp-ux-10-20,  Up: other-unix-notes

2.13.5.2 HP-UX Version 11.x Notes
.................................

If you install MySQL using a binary tarball distribution on HP-UX, you
may run into trouble even before you get the MySQL distribution
unpacked, as the HP-UX `tar' cannot handle long filenames. This means
that you may see errors when you try to unpack MySQL.

If this occurs, you must use GNU `tar' (`gtar') to unpack the
distribution.

Because of some critical bugs in the standard HP-UX libraries, you
should install the following patches before trying to run MySQL on
HP-UX 11.0:

     PHKL_22840 Streams cumulative
     PHNE_22397 ARPA cumulative

This solves the problem of getting `EWOULDBLOCK' from `recv()' and
`EBADF' from `accept()' in threaded applications.

If you are using `gcc' 2.95.1 on an unpatched HP-UX 11.x system, you
may get the following error:

     In file included from /usr/include/unistd.h:11,
                      from ../include/global.h:125,
                      from mysql_priv.h:15,
                      from item.cc:19:
     /usr/include/sys/unistd.h:184: declaration of C function ...
     /usr/include/sys/pthread.h:440: previous declaration ...
     In file included from item.h:306,
                      from mysql_priv.h:158,
                      from item.cc:19:

The problem is that HP-UX does not define `pthreads_atfork()'
consistently. It has conflicting prototypes in
`/usr/include/sys/unistd.h':184 and `/usr/include/sys/pthread.h':440.

One solution is to copy `/usr/include/sys/unistd.h' into
`mysql/include' and edit `unistd.h' and change it to match the
definition in `pthread.h'. Look for this line:

     extern int pthread_atfork(void (*prepare)(), void (*parent)(),
                                               void (*child)());

Change it to look like this:

     extern int pthread_atfork(void (*prepare)(void), void (*parent)(void),
                                               void (*child)(void));

After making the change, the following `configure' line should work:

     CFLAGS="-fomit-frame-pointer -O3 -fpic" CXX=gcc \
     CXXFLAGS="-felide-constructors -fno-exceptions -fno-rtti -O3" \
     ./configure --prefix=/usr/local/mysql --disable-shared

If you are using HP-UX compiler, you can use the following command
(which has been tested with `cc' B.11.11.04):

     CC=cc CXX=aCC CFLAGS=+DD64 CXXFLAGS=+DD64 ./configure \
         --with-extra-character-set=complex

You can ignore any errors of the following type:

     aCC: warning 901: unknown option: `-3': use +help for online
     documentation

If you get the following error from `configure', verify that you don't
have the path to the K&R compiler before the path to the HP-UX C and
C++ compiler:

     checking for cc option to accept ANSI C... no
     configure: error: MySQL requires an ANSI C compiler (and a C++ compiler).
     Try gcc. See the Installation chapter in the Reference Manual.

Another reason for not being able to compile is that you didn't define
the `+DD64' flags as just described.

Another possibility for HP-UX 11 is to use the MySQL binaries provided
at `http://dev.mysql.com/downloads/', which we have built and tested
ourselves. We have also received reports that the HP-UX 10.20 binaries
supplied by MySQL can be run successfully on HP-UX 11. If you encounter
problems, you should be sure to check your HP-UX patch level.


File: manual.info,  Node: ibm-aix,  Next: sunos,  Prev: hp-ux-11-x,  Up: other-unix-notes

2.13.5.3 IBM-AIX notes
......................

Automatic detection of `xlC' is missing from Autoconf, so a number of
variables need to be set before running `configure'. The following
example uses the IBM compiler:

     export CC="xlc_r -ma -O3 -qstrict -qoptimize=3 -qmaxmem=8192 "
     export CXX="xlC_r -ma -O3 -qstrict -qoptimize=3 -qmaxmem=8192"
     export CFLAGS="-I /usr/local/include"
     export LDFLAGS="-L /usr/local/lib"
     export CPPFLAGS=$CFLAGS
     export CXXFLAGS=$CFLAGS

     ./configure --prefix=/usr/local \
                     --localstatedir=/var/mysql \
                     --sbindir='/usr/local/bin' \
                     --libexecdir='/usr/local/bin' \
                     --enable-thread-safe-client \
                     --enable-large-files

The preceding options are used to compile the MySQL distribution that
can be found at `http://www-frec.bull.com/'.

If you change the `-O3' to `-O2' in the preceding `configure' line, you
must also remove the `-qstrict' option. This is a limitation in the IBM
C compiler.

If you are using `gcc' to compile MySQL, you _must_ use the
`-fno-exceptions' flag, because the exception handling in `gcc' is not
thread-safe! There are also some known problems with IBM's assembler
that may cause it to generate bad code when used with `gcc'.

We recommend the following `configure' line with `gcc' 2.95 on AIX:

     CC="gcc -pipe -mcpu=power -Wa,-many" \
     CXX="gcc -pipe -mcpu=power -Wa,-many" \
     CXXFLAGS="-felide-constructors -fno-exceptions -fno-rtti" \
     ./configure --prefix=/usr/local/mysql --with-low-memory

The `-Wa,-many' option is necessary for the compile to be successful.
IBM is aware of this problem but is in no hurry to fix it because of
the workaround that is available. We don't know if the
`-fno-exceptions' is required with `gcc' 2.95, but because MySQL
doesn't use exceptions and the option generates faster code, we
recommend that you should always use it with `gcc'.

If you get a problem with assembler code, try changing the `-mcpu=XXX'
option to match your CPU. Typically `power2', `power', or `powerpc' may
need to be used. Alternatively, you might need to use `604' or `604e'.
We are not positive but suspect that `power' would likely be safe most
of the time, even on a power2 machine.

If you don't know what your CPU is, execute a `uname -m' command. It
produces a string that looks like `000514676700', with a format of
`xxyyyyyymmss' where `xx' and `ss' are always `00', `yyyyyy' is a
unique system ID and `mm' is the ID of the CPU Planar. A chart of these
values can be found at
`http://www16.boulder.ibm.com/pseries/en_US/cmds/aixcmds5/uname.htm'.

This gives you a machine type and a machine model you can use to
determine what type of CPU you have.

If you have problems with signals (MySQL dies unexpectedly under high
load), you may have found an OS bug with threads and signals. In this
case, you can tell MySQL not to use signals by configuring as follows:

     CFLAGS=-DDONT_USE_THR_ALARM CXX=gcc \
     CXXFLAGS="-felide-constructors -fno-exceptions -fno-rtti \
     -DDONT_USE_THR_ALARM" \
     ./configure --prefix=/usr/local/mysql --with-debug \
         --with-low-memory

This doesn't affect the performance of MySQL, but has the side effect
that you can't kill clients that are `sleeping' on a connection with
`mysqladmin kill' or `mysqladmin shutdown'. Instead, the client dies
when it issues its next command.

On some versions of AIX, linking with `libbind.a' makes
`getservbyname()' dump core. This is an AIX bug and should be reported
to IBM.

For AIX 4.2.1 and `gcc', you have to make the following changes.

After configuring, edit `config.h' and `include/my_config.h' and change
the line that says this:

     #define HAVE_SNPRINTF 1

to this:

     #undef HAVE_SNPRINTF

And finally, in `mysqld.cc', you need to add a prototype for
`initgroups()'.

     #ifdef _AIX41
     extern "C" int initgroups(const char *,int);
     #endif

For 32-bit binaries, if you need to allocate a lot of memory to the
`mysqld' process, it's not enough to just use `ulimit -d unlimited'.
You may also have to modify `mysqld_safe' to add a line something like
this:

     export LDR_CNTRL='MAXDATA=0x80000000'

You can find more information about using a lot of memory at
`http://publib16.boulder.ibm.com/pseries/en_US/aixprggd/genprogc/lrg_prg_support.htm'.

Users of AIX 4.3 should use `gmake' instead of the `make' utility
included with AIX.

As of AIX 4.1, the C compiler has been unbundled from AIX as a separate
product. We recommend using `gcc' 3.3.2, which can be obtained here:
`ftp://ftp.software.ibm.com/aix/freeSoftware/aixtoolbox/RPMS/ppc/gcc/'

The steps for compiling MySQL on AIX with `gcc' 3.3.2 are similar to
those for using `gcc' 2.95 (in particular, the need to edit `config.h'
and `my_config.h' after running `configure'). However, before running
`configure', you should also patch the `curses.h' file as follows:

     /opt/freeware/lib/gcc-lib/powerpc-ibm-aix5.2.0.0/3.3.2/include/curses.h.ORIG
            Mon Dec 26 02:17:28 2005
     --- /opt/freeware/lib/gcc-lib/powerpc-ibm-aix5.2.0.0/3.3.2/include/curses.h
     Mon Dec 26 02:40:13 2005
     ***************
     *** 2023,2029 ****

       #endif /* _AIX32_CURSES */
     ! #if defined(__USE_FIXED_PROTOTYPES__) || defined(__cplusplus) || defined
     (__STRICT_ANSI__)
       extern int delwin (WINDOW *);
       extern int endwin (void);
       extern int getcurx (WINDOW *);
     --- 2023,2029 ----

       #endif /* _AIX32_CURSES */
     ! #if 0 && (defined(__USE_FIXED_PROTOTYPES__) || defined(__cplusplus)
     || defined
     (__STRICT_ANSI__))
       extern int delwin (WINDOW *);
       extern int endwin (void);
       extern int getcurx (WINDOW *);


File: manual.info,  Node: sunos,  Next: alpha-dec-unix,  Prev: ibm-aix,  Up: other-unix-notes

2.13.5.4 SunOS 4 Notes
......................

On SunOS 4, MIT-pthreads is needed to compile MySQL. This in turn means
you need GNU `make'.

Some SunOS 4 systems have problems with dynamic libraries and
`libtool'. You can use the following `configure' line to avoid this
problem:

     ./configure --disable-shared --with-mysqld-ldflags=-all-static

When compiling `readline', you may get warnings about duplicate
defines. These can be ignored.

When compiling `mysqld', there are some `implicit declaration of
function' warnings.  These can be ignored.


File: manual.info,  Node: alpha-dec-unix,  Next: alpha-dec-osf1,  Prev: sunos,  Up: other-unix-notes

2.13.5.5 Alpha-DEC-UNIX Notes (Tru64)
.....................................

If you are using `egcs' 1.1.2 on Digital Unix, you should upgrade to
`gcc' 2.95.2, because `egcs' on DEC has some serious bugs!

When compiling threaded programs under Digital Unix, the documentation
recommends using the `-pthread' option for `cc' and `cxx' and the
`-lmach -lexc' libraries (in addition to `-lpthread'). You should run
`configure' something like this:

     CC="cc -pthread" CXX="cxx -pthread -O" \
     ./configure --with-named-thread-libs="-lpthread -lmach -lexc -lc"

When compiling `mysqld', you may see a couple of warnings like this:

     mysqld.cc: In function void handle_connections()':
     mysqld.cc:626: passing long unsigned int *' as argument 3 of
     accept(int,sockadddr *, int *)'

You can safely ignore these warnings. They occur because `configure'
can detect only errors, not warnings.

If you start the server directly from the command line, you may have
problems with it dying when you log out. (When you log out, your
outstanding processes receive a `SIGHUP' signal.) If so, try starting
the server like this:

     nohup mysqld [OPTIONS] &

`nohup' causes the command following it to ignore any `SIGHUP' signal
sent from the terminal. Alternatively, start the server by running
`mysqld_safe', which invokes `mysqld' using `nohup' for you. See *Note
mysqld-safe::.

If you get a problem when compiling `mysys/get_opt.c', just remove the
`#define _NO_PROTO' line from the start of that file.

If you are using Compaq's CC compiler, the following `configure' line
should work:

     CC="cc -pthread"
     CFLAGS="-O4 -ansi_alias -ansi_args -fast -inline speed \
             -speculate all -arch host"
     CXX="cxx -pthread"
     CXXFLAGS="-O4 -ansi_alias -ansi_args -fast -inline speed \
               -speculate all -arch host -noexceptions -nortti"
     export CC CFLAGS CXX CXXFLAGS
     ./configure \
         --prefix=/usr/local/mysql \
         --with-low-memory \
         --enable-large-files \
         --enable-shared=yes \
         --with-named-thread-libs="-lpthread -lmach -lexc -lc"
     gnumake

If you get a problem with `libtool' when compiling with shared
libraries as just shown, when linking `mysql', you should be able to
get around this by issuing these commands:

     cd mysql
     /bin/sh ../libtool --mode=link cxx -pthread  -O3 -DDBUG_OFF \
         -O4 -ansi_alias -ansi_args -fast -inline speed \
         -speculate all \ -arch host  -DUNDEF_HAVE_GETHOSTBYNAME_R \
         -o mysql  mysql.o readline.o sql_string.o completion_hash.o \
         ../readline/libreadline.a -lcurses \
         ../libmysql/.libs/libmysqlclient.so  -lm
     cd ..
     gnumake
     gnumake install
     scripts/mysql_install_db


File: manual.info,  Node: alpha-dec-osf1,  Next: sgi-irix,  Prev: alpha-dec-unix,  Up: other-unix-notes

2.13.5.6 Alpha-DEC-OSF/1 Notes
..............................

If you have problems compiling and have DEC `CC' and `gcc' installed,
try running `configure' like this:

     CC=cc CFLAGS=-O CXX=gcc CXXFLAGS=-O3 \
     ./configure --prefix=/usr/local/mysql

If you get problems with the `c_asm.h' file, you can create and use a
'dummy' `c_asm.h' file with:

     touch include/c_asm.h
     CC=gcc CFLAGS=-I./include \
     CXX=gcc CXXFLAGS=-O3 \
     ./configure --prefix=/usr/local/mysql

Note that the following problems with the `ld' program can be fixed by
downloading the latest DEC (Compaq) patch kit from:
`http://ftp.support.compaq.com/public/unix/'.

On OSF/1 V4.0D and compiler "DEC C V5.6-071 on Digital Unix V4.0 (Rev.
878)," the compiler had some strange behavior (undefined `asm' symbols).
`/bin/ld' also appears to be broken (problems with `_exit undefined'
errors occurring while linking `mysqld'). On this system, we have
managed to compile MySQL with the following `configure' line, after
replacing `/bin/ld' with the version from OSF 4.0C:

     CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql

With the Digital compiler "C++ V6.1-029," the following should work:

     CC=cc -pthread
     CFLAGS=-O4 -ansi_alias -ansi_args -fast -inline speed \
            -speculate all -arch host
     CXX=cxx -pthread
     CXXFLAGS=-O4 -ansi_alias -ansi_args -fast -inline speed \
              -speculate all -arch host -noexceptions -nortti
     export CC CFLAGS CXX CXXFLAGS
     ./configure --prefix=/usr/mysql/mysql \
                 --with-mysqld-ldflags=-all-static --disable-shared \
                 --with-named-thread-libs="-lmach -lexc -lc"

In some versions of OSF/1, the `alloca()' function is broken. Fix this
by removing the line in `config.h' that defines `'HAVE_ALLOCA''.

The `alloca()' function also may have an incorrect prototype in
`/usr/include/alloca.h'. This warning resulting from this can be
ignored.

`configure' uses the following thread libraries automatically:
`--with-named-thread-libs="-lpthread -lmach -lexc -lc"'.

When using `gcc', you can also try running `configure' like this:

     CFLAGS=-D_PTHREAD_USE_D4 CXX=gcc CXXFLAGS=-O3 ./configure ...

If you have problems with signals (MySQL dies unexpectedly under high
load), you may have found an OS bug with threads and signals. In this
case, you can tell MySQL not to use signals by configuring with:

     CFLAGS=-DDONT_USE_THR_ALARM \
     CXXFLAGS=-DDONT_USE_THR_ALARM \
     ./configure ...

This does not affect the performance of MySQL, but has the side effect
that you can't kill clients that are `sleeping' on a connection with
`mysqladmin kill' or `mysqladmin shutdown'. Instead, the client dies
when it issues its next command.

With `gcc' 2.95.2, you may encounter the following compile error:

     sql_acl.cc:1456: Internal compiler error in `scan_region',
     at except.c:2566
     Please submit a full bug report.

To fix this, you should change to the `sql' directory and do a
cut-and-paste of the last `gcc' line, but change `-O3' to `-O0' (or add
`-O0' immediately after `gcc' if you don't have any `-O' option on your
compile line). After this is done, you can just change back to the
top-level directory and run `make' again.


File: manual.info,  Node: sgi-irix,  Next: sco,  Prev: alpha-dec-osf1,  Up: other-unix-notes

2.13.5.7 SGI Irix Notes
.......................

As of MySQL 5.0, we don't provide binaries for Irix any more.

If you are using Irix 6.5.3 or newer, `mysqld' is able to create
threads only if you run it as a user that has `CAP_SCHED_MGT'
privileges (such as `root') or give the `mysqld' server this privilege
with the following shell command:

     chcap "CAP_SCHED_MGT+epi" /opt/mysql/libexec/mysqld

You may have to undefine some symbols in `config.h' after running
`configure' and before compiling.

In some Irix implementations, the `alloca()' function is broken. If the
`mysqld' server dies on some `SELECT' statements, remove the lines from
`config.h' that define `HAVE_ALLOC' and `HAVE_ALLOCA_H'. If `mysqladmin
create' doesn't work, remove the line from `config.h' that defines
`HAVE_READDIR_R'. You may have to remove the `HAVE_TERM_H' line as well.

SGI recommends that you install all the patches on this page as a set:
`http://support.sgi.com/surfzone/patches/patchset/6.2_indigo.rps.html'

At the very minimum, you should install the latest kernel rollup, the
latest `rld' rollup, and the latest `libc' rollup.

You definitely need all the POSIX patches on this page, for pthreads
support:

`http://support.sgi.com/surfzone/patches/patchset/6.2_posix.rps.html'

If you get the something like the following error when compiling
`mysql.cc':

     "/usr/include/curses.h", line 82: error(1084):
     invalid combination of type

Type the following in the top-level directory of your MySQL source tree:

     extra/replace bool curses_bool < /usr/include/curses.h > include/curses.h
     make

There have also been reports of scheduling problems. If only one thread
is running, performance is slow. Avoid this by starting another client.
This may lead to a two-to-tenfold increase in execution speed
thereafter for the other thread.  This is a poorly understood problem
with Irix threads; you may have to improvise to find solutions until
this can be fixed.

If you are compiling with `gcc', you can use the following `configure'
command:

     CC=gcc CXX=gcc CXXFLAGS=-O3 \
     ./configure --prefix=/usr/local/mysql --enable-thread-safe-client \
         --with-named-thread-libs=-lpthread

On Irix 6.5.11 with native Irix C and C++ compilers ver.  7.3.1.2, the
following is reported to work

     CC=cc CXX=CC CFLAGS='-O3 -n32 -TARG:platform=IP22 -I/usr/local/include \
     -L/usr/local/lib' CXXFLAGS='-O3 -n32 -TARG:platform=IP22 \
     -I/usr/local/include -L/usr/local/lib' \
     ./configure --prefix=/usr/local/mysql --with-innodb \
         --with-libwrap=/usr/local \
         --with-named-curses-libs=/usr/local/lib/libncurses.a


File: manual.info,  Node: sco,  Next: sco-openserver,  Prev: sgi-irix,  Up: other-unix-notes

2.13.5.8 SCO UNIX and OpenServer 5.0.x Notes
............................................

The current port is tested only on `sco3.2v5.0.5', `sco3.2v5.0.6', and
`sco3.2v5.0.7' systems. There has also been progress on a port to
`sco3.2v4.2'. Open Server 5.0.8 (Legend) has native threads and allows
files greater than 2GB. The current maximum file size is 2GB.

We have been able to compile MySQL with the following `configure'
command on OpenServer with `gcc' 2.95.3.

     CC=gcc CFLAGS="-D_FILE_OFFSET_BITS=64 -O3" \
     CXX=gcc CXXFLAGS="-D_FILE_OFFSET_BITS=64 -O3" \
     ./configure --prefix=/usr/local/mysql \
         --enable-thread-safe-client --with-innodb \
         --with-openssl --with-vio --with-extra-charsets=complex

`gcc' is available at
`ftp://ftp.sco.com/pub/openserver5/opensrc/gnutools-5.0.7Kj'.

This development system requires the OpenServer Execution Environment
Supplement oss646B on OpenServer 5.0.6 and oss656B and The OpenSource
libraries found in gwxlibs. All OpenSource tools are in the `opensrc'
directory. They are available at
`ftp://ftp.sco.com/pub/openserver5/opensrc/'.

We recommend using the latest production release of MySQL.

SCO provides operating system patches at
`ftp://ftp.sco.com/pub/openserver5' for OpenServer 5.0.[0-6] and
`ftp://ftp.sco.com/pub/openserverv5/507' for OpenServer 5.0.7.

SCO provides information about security fixes at
`ftp://ftp.sco.com/pub/security/OpenServer' for OpenServer 5.0.x.

The maximum file size on an OpenSever 5.0.x system is 2GB.

The total memory which can be allocated for streams buffers, clists,
and lock records cannot exceed 60MB on OpenServer 5.0.x.

Streams buffers are allocated in units of 4096 byte pages, clists are
70 bytes each, and lock records are 64 bytes each, so:

     (NSTRPAGES x 4096) + (NCLIST x 70) + (MAX_FLCKREC x 64) <= 62914560

Follow this procedure to configure the Database Services option. If you
are unsure whether an application requires this, see the documentation
provided with the application.

  1. Log in as `root'.

  2. Enable the SUDS driver by editing the `/etc/conf/sdevice.d/suds'
     file. Change the `N' in the second field to a `Y'.

  3. Use `mkdev aio' or the Hardware/Kernel Manager to enable support
     for asynchronous I/O and relink the kernel. To allow users to lock
     down memory for use with this type of I/O, update the
     aiomemlock(F) file. This file should be updated to include the
     names of users that can use AIO and the maximum amounts of memory
     they can lock down.

  4. Many applications use setuid binaries so that you need to specify
     only a single user. See the documentation provided with the
     application to determine whether this is the case for your
     application.

After you complete this process, reboot the system to create a new
kernel incorporating these changes.

By default, the entries in `/etc/conf/cf.d/mtune' are set as follows:

     Value           Default         Min             Max
     -----           -------         ---             ---
     NBUF            0               24              450000
     NHBUF           0               32              524288
     NMPBUF          0               12              512
     MAX_INODE       0               100             64000
     MAX_FILE        0               100             64000
     CTBUFSIZE       128             0               256
     MAX_PROC        0               50              16000
     MAX_REGION      0               500             160000
     NCLIST          170             120             16640
     MAXUP           100             15              16000
     NOFILES         110             60              11000
     NHINODE         128             64              8192
     NAUTOUP         10              0               60
     NGROUPS         8               0               128
     BDFLUSHR        30              1               300
     MAX_FLCKREC     0               50              16000
     PUTBUFSZ        8000            2000            20000
     MAXSLICE        100             25              100
     ULIMIT          4194303         2048            4194303
     * Streams Parameters
     NSTREAM         64              1               32768
     NSTRPUSH        9               9               9
     NMUXLINK        192             1               4096
     STRMSGSZ        16384           4096            524288
     STRCTLSZ        1024            1024            1024
     STRMAXBLK       524288          4096            524288
     NSTRPAGES       500             0               8000
     STRSPLITFRAC    80              50              100
     NLOG            3               3               3
     NUMSP           64              1               256
     NUMTIM          16              1               8192
     NUMTRW          16              1               8192
     * Semaphore Parameters
     SEMMAP          10              10              8192
     SEMMNI          10              10              8192
     SEMMNS          60              60              8192
     SEMMNU          30              10              8192
     SEMMSL          25              25              150
     SEMOPM          10              10              1024
     SEMUME          10              10              25
     SEMVMX          32767           32767           32767
     SEMAEM          16384           16384           16384
     * Shared Memory Parameters
     SHMMAX          524288          131072          2147483647
     SHMMIN          1               1               1
     SHMMNI          100             100             2000
     FILE            0               100             64000
     NMOUNT          0               4               256
     NPROC           0               50              16000
     NREGION         0               500             160000

We recommend setting these values as follows:

   * `NOFILES' should be 4096 or 2048.

   * `MAXUP' should be 2048.

To make changes to the kernel, use the `idtune NAME PARAMETER' command.
`idtune' modifies the `/etc/conf/cf.d/stune' file for you. For example,
to change `SEMMS' to `200', execute this command as `root':

     # /etc/conf/bin/idtune SEMMNS 200

Then rebuild and reboot the kernel by issuing this command:

     # /etc/conf/bin/idbuild -B && init 6

We recommend tuning the system, but the proper parameter values to use
depend on the number of users accessing the application or database and
size the of the database (that is, the used buffer pool). The following
kernel parameters can be set with `idtune':

   * `SHMMAX' (recommended setting: 128MB) and `SHMSEG' (recommended
     setting: 15). These parameters have an influence on the MySQL
     database engine to create user buffer pools.

   * `NOFILES' and `MAXUP' should be set to at least 2048.

   * `MAXPROC' should be set to at least 3000/4000 (depends on number
     of users) or more.

   * We also recommend using the following formulas to calculate values
     for `SEMMSL', `SEMMNS', and `SEMMNU':

          SEMMSL = 13

     13 is what has been found to be the best for both Progress and
     MySQL.

          SEMMNS = SEMMSL x NUMBER OF DB SERVERS TO BE RUN ON THE SYSTEM

     Set `SEMMNS' to the value of `SEMMSL' multiplied by the number of
     database servers (maximum) that you are running on the system at
     one time.

          SEMMNU = SEMMNS

     Set the value of `SEMMNU' to equal the value of `SEMMNS'. You
     could probably set this to 75% of `SEMMNS', but this is a
     conservative estimate.

You need to at least install the SCO OpenServer Linker and Application
Development Libraries or the OpenServer Development System to use
`gcc'. You cannot use the GCC Dev system without installing one of
these.

You should get the FSU Pthreads package and install it first.  This can
be found at
`http://moss.csc.ncsu.edu/~mueller/ftp/pub/PART/pthreads.tar.gz'.  You
can also get a precompiled package from
`ftp://ftp.zenez.com/pub/zenez/prgms/FSU-threads-3.14.tar.gz'.

FSU Pthreads can be compiled with SCO Unix 4.2 with tcpip, or using
OpenServer 3.0 or Open Desktop 3.0 (OS 3.0 ODT 3.0) with the SCO
Development System installed using a good port of GCC 2.5.x. For ODT or
OS 3.0, you need a good port of GCC 2.5.x.  There are a lot of problems
without a good port. The port for this product requires the SCO Unix
Development system. Without it, you are missing the libraries and the
linker that is needed. You also need `SCO-3.2v4.2-includes.tar.gz'.
This file contains the changes to the SCO Development include files that
are needed to get MySQL to build. You need to replace the existing
system include files with these modified header files. They can be
obtained from
`ftp://ftp.zenez.com/pub/zenez/prgms/SCO-3.2v4.2-includes.tar.gz'.

To build FSU Pthreads on your system, all you should need to do is run
GNU `make'. The `Makefile' in FSU-threads-3.14.tar.gz is set up to make
FSU-threads.

You can run `./configure' in the `threads/src' directory and select the
SCO OpenServer option. This command copies `Makefile.SCO5' to
`Makefile'. Then run `make'.

To install in the default `/usr/include' directory, log in as `root',
and then `cd' to the `thread/src' directory and run `make install'.

Remember that you must use GNU `make' to build MySQL.

*Note*:

If you don't start `mysqld_safe' as `root', you should get only the
default 110 open files per process. `mysqld' writes a note about this
in the log file.

With SCO 3.2V4.2, you should use FSU Pthreads version 3.14 or newer.
The following `configure' command should work:

     CFLAGS="-D_XOPEN_XPG4" CXX=gcc CXXFLAGS="-D_XOPEN_XPG4" \
     ./configure \
         --prefix=/usr/local/mysql \
         --with-named-thread-libs="-lgthreads -lsocket -lgen -lgthreads" \
         --with-named-curses-libs="-lcurses"

You may have problems with some include files. In this case, you can
find new SCO-specific include files at
`ftp://ftp.zenez.com/pub/zenez/prgms/SCO-3.2v4.2-includes.tar.gz'.

You should unpack this file in the `include' directory of your MySQL
source tree.

SCO development notes:

   * MySQL should automatically detect FSU Pthreads and link `mysqld'
     with `-lgthreads -lsocket -lgthreads'.

   * The SCO development libraries are re-entrant in FSU Pthreads. SCO
     claims that its library functions are re-entrant, so they must be
     re-entrant with FSU Pthreads.  FSU Pthreads on OpenServer tries to
     use the SCO scheme to make re-entrant libraries.

   * FSU Pthreads (at least the version at `ftp://ftp.zenez.com') comes
     linked with GNU `malloc'. If you encounter problems with memory
     usage, make sure that `gmalloc.o' is included in `libgthreads.a'
     and `libgthreads.so'.

   * In FSU Pthreads, the following system calls are pthreads-aware:
     `read()', `write()', `getmsg()', `connect()', `accept(),'
     `select()', and `wait()'.

   * The CSSA-2001-SCO.35.2 (the patch is listed in custom as
     erg711905-dscr_remap security patch (version 2.0.0)) breaks FSU
     threads and makes `mysqld' unstable. You have to remove this one
     if you want to run `mysqld' on an OpenServer 5.0.6 machine.

   * If you use SCO OpenServer 5, you may need to recompile FSU
     pthreads with `-DDRAFT7' in `CFLAGS'. Otherwise, `InnoDB' may hang
     at a `mysqld' startup.

   * SCO provides operating system patches at
     `ftp://ftp.sco.com/pub/openserver5' for OpenServer 5.0.x.

   * SCO provides security fixes and `libsocket.so.2' at
     `ftp://ftp.sco.com/pub/security/OpenServer' and
     `ftp://ftp.sco.com/pub/security/sse' for OpenServer 5.0.x.

   * Pre-OSR506 security fixes. Also, the `telnetd' fix at
     `ftp://stage.caldera.com/pub/security/openserver/' or
     `ftp://stage.caldera.com/pub/security/openserver/CSSA-2001-SCO.10/'
     as both `libsocket.so.2' and `libresolv.so.1' with instructions for
     installing on pre-OSR506 systems.

     It's probably a good idea to install these patches before trying
     to compile/use MySQL.

Beginning with Legend/OpenServer 6.0.0, there are native threads and no
2GB file size limit.


File: manual.info,  Node: sco-openserver,  Next: sco-unixware,  Prev: sco,  Up: other-unix-notes

2.13.5.9 SCO OpenServer 6.0.x Notes
...................................

OpenServer 6 includes these key improvements:

   * Larger file support up to 1 TB

   * Multiprocessor support increased from 4 to 32 processors

   * Increased memory support up to 64GB

   * Extending the power of UnixWare into OpenServer 6

   * Dramatic performance improvement

OpenServer 6.0.0 commands are organized as follows:

   * `/bin' is for commands that behave exactly the same as on
     OpenServer 5.0.x.

   * `/u95/bin' is for commands that have better standards conformance,
     for example Large File System (LFS) support.

   * `/udk/bin' is for commands that behave the same as on UnixWare
     7.1.4. The default is for the LFS support.

The following is a guide to setting `PATH' on OpenServer 6. If the user
wants the traditional OpenServer 5.0.x then `PATH' should be `/bin'
first. If the user wants LFS support, the path should be
`/u95/bin:/bin'. If the user wants UnixWare 7 support first, the path
would be `/udk/bin:/u95/bin:/bin:'.

We recommend using the latest production release of MySQL.  Should you
choose to use an older release of MySQL on OpenServer 6.0.x, you must
use a version of MySQL at least as recent as 3.22.13 to get fixes for
some portability and OS problems.

MySQL distribution files with names of the following form are `tar'
archives of media are tar archives of media images suitable for
installation with the SCO Software Manager (`/etc/custom') on SCO
OpenServer 6:

     mysql-PRODUCT-5.1.28-sco-osr6-i686.VOLS.tar

A distribution where PRODUCT is `pro-cert' is the Commercially licensed
MySQL Pro Certified server. A distribution where PRODUCT is
`pro-gpl-cert' is the MySQL Pro Certified server licensed under the
terms of the General Public License (GPL).

Select whichever distribution you wish to install and, after download,
extract the `tar' archive into an empty directory. For example:

     shell> mkdir /tmp/mysql-pro
     shell> cd /tmp/mysql-pro
     shell> tar xf /tmp/mysql-pro-cert-5.1.28-sco-osr6-i686.VOLS.tar

Prior to installation, back up your data in accordance with the
procedures outlined in *Note upgrade::.

Remove any previously installed `pkgadd' version of MySQL:

     shell> pkginfo mysql 2>&1 > /dev/null && pkgrm mysql

Install MySQL Pro from media images using the SCO Software Manager:

     shell> /etc/custom -p SCO:MySQL -i -z /tmp/mysql-pro

Alternatively, the SCO Software Manager can be displayed graphically by
clicking on the `Software Manager' icon on the desktop, selecting
`Software -> Install New', selecting the host, selecting `Media Images'
for the Media Device, and entering `/tmp/mysql-pro' as the Image
Directory.

After installation, run `mkdev mysql' as the `root' user to configure
your newly installed MySQL Pro Certified server.

*Note*:

The installation procedure for VOLS packages does not create the
`mysql' user and group that the package uses by default. You should
either create the `mysql' user and group, or else select a different
user and group using an option in `mkdev mysql'.

If you wish to configure your MySQL Pro server to interface with the
Apache Web server via PHP, download and install the PHP update from SCO
at `ftp://ftp.sco.com/pub/updates/OpenServer/SCOSA-2006.17/'.

We have been able to compile MySQL with the following `configure'
command on OpenServer 6.0.x:

     CC=cc CFLAGS="-D_FILE_OFFSET_BITS=64 -O3" \
     CXX=CC CXXFLAGS="-D_FILE_OFFSET_BITS=64 -O3" \
     ./configure --prefix=/usr/local/mysql \
         --enable-thread-safe-client  \
         --with-extra-charsets=complex \
         --build=i686-unknown-sysv5SCO_SV6.0.0

If you use `gcc', you must use `gcc' 2.95.3 or newer.

     CC=gcc CXX=g++ ... ./configure ...

SCO provides OpenServer 6 operating system patches at
`ftp://ftp.sco.com/pub/openserver6'.

SCO provides information about security fixes at
`ftp://ftp.sco.com/pub/security/OpenServer'.

By default, the maximum file size on a OpenServer 6.0.0 system is 1TB.
Some operating system utilities have a limitation of 2GB. The maximum
possible file size on UnixWare 7 is 1TB with VXFS or HTFS.

OpenServer 6 can be configured for large file support (file sizes
greater than 2GB) by tuning the UNIX kernel.

By default, the entries in `/etc/conf/cf.d/mtune' are set as follows:

     Value           Default         Min             Max
     -----           -------         ---             ---
     SVMMLIM         0x9000000       0x1000000       0x7FFFFFFF
     HVMMLIM         0x9000000       0x1000000       0x7FFFFFFF

To make changes to the kernel, use the `idtune NAME PARAMETER' command.
`idtune' modifies the `/etc/conf/cf.d/stune' file for you. We recommend
setting the kernel values by executing the following commands as `root':

     # /etc/conf/bin/idtune SDATLIM 0x7FFFFFFF
     # /etc/conf/bin/idtune HDATLIM 0x7FFFFFFF
     # /etc/conf/bin/idtune SVMMLIM 0x7FFFFFFF
     # /etc/conf/bin/idtune HVMMLIM 0x7FFFFFFF
     # /etc/conf/bin/idtune SFNOLIM 2048
     # /etc/conf/bin/idtune HFNOLIM 2048

Then rebuild and reboot the kernel by issuing this command:

     # /etc/conf/bin/idbuild -B && init 6

We recommend tuning the system, but the proper parameter values to use
depend on the number of users accessing the application or database and
size the of the database (that is, the used buffer pool). The following
kernel parameters can be set with `idtune':

   * `SHMMAX' (recommended setting: 128MB) and `SHMSEG' (recommended
     setting: 15). These parameters have an influence on the MySQL
     database engine to create user buffer pools.

   * `SFNOLIM' and `HFNOLIM' should be at maximum 2048.

   * `NPROC' should be set to at least 3000/4000 (depends on number of
     users).

   * We also recommend using the following formulas to calculate values
     for `SEMMSL', `SEMMNS', and `SEMMNU':

          SEMMSL = 13

     13 is what has been found to be the best for both Progress and
     MySQL.

          SEMMNS = SEMMSL x NUMBER OF DB SERVERS TO BE RUN ON THE SYSTEM

     Set `SEMMNS' to the value of `SEMMSL' multiplied by the number of
     database servers (maximum) that you are running on the system at
     one time.

          SEMMNU = SEMMNS

     Set the value of `SEMMNU' to equal the value of `SEMMNS'. You
     could probably set this to 75% of `SEMMNS', but this is a
     conservative estimate.


File: manual.info,  Node: sco-unixware,  Prev: sco-openserver,  Up: other-unix-notes

2.13.5.10 SCO UnixWare 7.1.x and OpenUNIX 8.0.0 Notes
.....................................................

We recommend using the latest production release of MySQL.  Should you
choose to use an older release of MySQL on UnixWare 7.1.x, you must use
a version of MySQL at least as recent as 3.22.13 to get fixes for some
portability and OS problems.

We have been able to compile MySQL with the following `configure'
command on UnixWare 7.1.x:

     CC="cc" CFLAGS="-I/usr/local/include" \
     CXX="CC" CXXFLAGS="-I/usr/local/include" \
     ./configure --prefix=/usr/local/mysql \
         --enable-thread-safe-client \
         --with-innodb --with-openssl --with-extra-charsets=complex

If you want to use `gcc', you must use `gcc' 2.95.3 or newer.

     CC=gcc CXX=g++ ... ./configure ...

SCO provides operating system patches at
`ftp://ftp.sco.com/pub/unixware7' for UnixWare 7.1.1,
`ftp://ftp.sco.com/pub/unixware7/713/' for UnixWare 7.1.3,
`ftp://ftp.sco.com/pub/unixware7/714/' for UnixWare 7.1.4, and
`ftp://ftp.sco.com/pub/openunix8' for OpenUNIX 8.0.0.

SCO provides information about security fixes at
`ftp://ftp.sco.com/pub/security/OpenUNIX' for OpenUNIX and
`ftp://ftp.sco.com/pub/security/UnixWare' for UnixWare.

The UnixWare 7 file size limit is 1 TB with VXFS. Some OS utilities
have a limitation of 2GB.

On UnixWare 7.1.4 you do not need to do anything to get large file
support, but to enable large file support on prior versions of UnixWare
7.1.x, run `fsadm'.

     # fsadm -Fvxfs -o largefiles /
     # fsadm /         * Note
     # ulimit unlimited
     # /etc/conf/bin/idtune SFSZLIM 0x7FFFFFFF     ** Note
     # /etc/conf/bin/idtune HFSZLIM 0x7FFFFFFF     ** Note
     # /etc/conf/bin/idbuild -B

     * This should report "largefiles".
     ** 0x7FFFFFFF represents infinity for these values.

Reboot the system using `shutdown'.

By default, the entries in `/etc/conf/cf.d/mtune' are set as follows:

     Value           Default         Min             Max
     -----           -------         ---             ---
     SVMMLIM         0x9000000       0x1000000       0x7FFFFFFF
     HVMMLIM         0x9000000       0x1000000       0x7FFFFFFF

To make changes to the kernel, use the `idtune NAME PARAMETER' command.
`idtune' modifies the `/etc/conf/cf.d/stune' file for you. We recommend
setting the kernel values by executing the following commands as `root':

     # /etc/conf/bin/idtune SDATLIM 0x7FFFFFFF
     # /etc/conf/bin/idtune HDATLIM 0x7FFFFFFF
     # /etc/conf/bin/idtune SVMMLIM 0x7FFFFFFF
     # /etc/conf/bin/idtune HVMMLIM 0x7FFFFFFF
     # /etc/conf/bin/idtune SFNOLIM 2048
     # /etc/conf/bin/idtune HFNOLIM 2048

Then rebuild and reboot the kernel by issuing this command:

     # /etc/conf/bin/idbuild -B && init 6

We recommend tuning the system, but the proper parameter values to use
depend on the number of users accessing the application or database and
size the of the database (that is, the used buffer pool). The following
kernel parameters can be set with `idtune':

   * `SHMMAX' (recommended setting: 128MB) and `SHMSEG' (recommended
     setting: 15). These parameters have an influence on the MySQL
     database engine to create user buffer pools.

   * `SFNOLIM' and `HFNOLIM' should be at maximum 2048.

   * `NPROC' should be set to at least 3000/4000 (depends on number of
     users).

   * We also recommend using the following formulas to calculate values
     for `SEMMSL', `SEMMNS', and `SEMMNU':

          SEMMSL = 13

     13 is what has been found to be the best for both Progress and
     MySQL.

          SEMMNS = SEMMSL x NUMBER OF DB SERVERS TO BE RUN ON THE SYSTEM

     Set `SEMMNS' to the value of `SEMMSL' multiplied by the number of
     database servers (maximum) that you are running on the system at
     one time.

          SEMMNU = SEMMNS

     Set the value of `SEMMNU' to equal the value of `SEMMNS'. You
     could probably set this to 75% of `SEMMNS', but this is a
     conservative estimate.


File: manual.info,  Node: environment-variables,  Next: perl-support,  Prev: operating-system-specific-notes,  Up: installing

2.14 Environment Variables
==========================

This section lists all the environment variables that are used directly
or indirectly by MySQL. Most of these can also be found in other places
in this manual.

Note that any options on the command line take precedence over values
specified in option files and environment variables, and values in
option files take precedence over values in environment variables.

In many cases, it is preferable to use an option file instead of
environment variables to modify the behavior of MySQL. See *Note
option-files::.

*Variable*         *Description*
`CXX'              The name of your C++ compiler (for running
                   `configure').
`CC'               The name of your C compiler (for running `configure').
`CFLAGS'           Flags for your C compiler (for running `configure').
`CXXFLAGS'         Flags for your C++ compiler (for running `configure').
`DBI_USER'         The default username for Perl DBI.
`DBI_TRACE'        Trace options for Perl DBI.
`HOME'             The default path for the `mysql' history file is
                   `$HOME/.mysql_history'.
`LD_RUN_PATH'      Used to specify the location of `libmysqlclient.so'.
`MYSQL_DEBUG'      Debug trace options when debugging.
`MYSQL_GROUP_SUFFIX'Option group suffix value (like specifying
                   `--defaults-group-suffix').
`MYSQL_HISTFILE'   The path to the `mysql' history file. If this variable
                   is set, its value overrides the default for
                   `$HOME/.mysql_history'.
`MYSQL_HOME'       The path to the directory in which the server-specific
                   `my.cnf' file resides (as of MySQL 5.0.3).
`MYSQL_HOST'       The default hostname used by the `mysql' command-line
                   client.
`MYSQL_PS1'        The command prompt to use in the `mysql' command-line
                   client.
`MYSQL_PWD'        The default password when connecting to `mysqld'. Note
                   that using this is insecure. See *Note
                   password-security::.
`MYSQL_TCP_PORT'   The default TCP/IP port number.
`MYSQL_UNIX_PORT'  The default Unix socket filename; used for
                   connections to `localhost'.
`PATH'             Used by the shell to find MySQL programs.
`TMPDIR'           The directory where temporary files are created.
`TZ'               This should be set to your local time zone. See *Note
                   timezone-problems::.
`UMASK_DIR'        The user-directory creation mask when creating
                   directories. Note that this is `AND'ed with `UMASK'.
`UMASK'            The user-file creation mask when creating files.
`USER'             The default username on Windows and NetWare used when
                   connecting to `mysqld'.


File: manual.info,  Node: perl-support,  Prev: environment-variables,  Up: installing

2.15 Perl Installation Notes
============================

* Menu:

* perl-installation::            Installing Perl on Unix
* activestate-perl::             Installing ActiveState Perl on Windows
* perl-support-problems::        Problems Using the Perl `DBI'/`DBD' Interface

Perl support for MySQL is provided by means of the `DBI'/`DBD' client
interface.  The interface requires Perl 5.6.0, and 5.6.1 or later is
preferred. DBI _does not work_ if you have an older version of Perl.

If you want to use transactions with Perl DBI, you need to have
`DBD::mysql' 2.0900. If you are using the MySQL 4.1 or newer client
library, you must use `DBD::mysql' 2.9003 or newer. Support for
server-side prepared statements requires `DBD::mysql' 3.0009 or newer.

Perl support is not included with MySQL distributions. You can obtain
the necessary modules from `http://search.cpan.org' for Unix, or by
using the ActiveState `ppm' program on Windows. The following sections
describe how to do this.

Perl support for MySQL must be installed if you want to run the MySQL
benchmark scripts; see *Note mysql-benchmarks::.  It is also required
for the MySQL Cluster `ndb_size.pl' utility; see *Note
mysql-cluster-utilities-ndb-size::.


File: manual.info,  Node: perl-installation,  Next: activestate-perl,  Prev: perl-support,  Up: perl-support

2.15.1 Installing Perl on Unix
------------------------------

MySQL Perl support requires that you have installed MySQL client
programming support (libraries and header files). Most installation
methods install the necessary files. However, if you installed MySQL
from RPM files on Linux, be sure that you've installed the developer
RPM. The client programs are in the client RPM, but client programming
support is in the developer RPM.

If you want to install Perl support, the files you need can be obtained
from the CPAN (Comprehensive Perl Archive Network) at
`http://search.cpan.org'.

The easiest way to install Perl modules on Unix is to use the `CPAN'
module. For example:

     shell> perl -MCPAN -e shell
     cpan> install DBI
     cpan> install DBD::mysql

The `DBD::mysql' installation runs a number of tests. These tests
attempt to connect to the local MySQL server using the default username
and password. (The default username is your login name on Unix, and
`ODBC' on Windows. The default password is `no password.') If you
cannot connect to the server with those values (for example, if your
account has a password), the tests fail. You can use `force install
DBD::mysql' to ignore the failed tests.

`DBI' requires the `Data::Dumper' module. It may be installed; if not,
you should install it before installing `DBI'.

It is also possible to download the module distributions in the form of
compressed `tar' archives and build the modules manually. For example,
to unpack and build a DBI distribution, use a procedure such as this:

  1. Unpack the distribution into the current directory:

          shell> gunzip < DBI-VERSION.tar.gz | tar xvf -

     This command creates a directory named `DBI-VERSION'.

  2. Change location into the top-level directory of the unpacked
     distribution:

          shell> cd DBI-VERSION

  3. Build the distribution and compile everything:

          shell> perl Makefile.PL
          shell> make
          shell> make test
          shell> make install

The `make test' command is important because it verifies that the
module is working. Note that when you run that command during the
`DBD::mysql' installation to exercise the interface code, the MySQL
server must be running or the test fails.

It is a good idea to rebuild and reinstall the `DBD::mysql'
distribution whenever you install a new release of MySQL, particularly
if you notice symptoms such as that all your `DBI' scripts fail after
you upgrade MySQL.

If you do not have access rights to install Perl modules in the system
directory or if you want to install local Perl modules, the following
reference may be useful:
`http://servers.digitaldaze.com/extensions/perl/modules.html#modules'

Look under the heading `Installing New Modules that Require Locally
Installed Modules.'


File: manual.info,  Node: activestate-perl,  Next: perl-support-problems,  Prev: perl-installation,  Up: perl-support

2.15.2 Installing ActiveState Perl on Windows
---------------------------------------------

On Windows, you should do the following to install the MySQL `DBD'
module with ActiveState Perl:

  1. Get ActiveState Perl from
     `http://www.activestate.com/Products/ActivePerl/' and install it.

  2. Open a console window (a `DOS window').

  3. If necessary, set the `HTTP_proxy' variable. For example, you
     might try a setting like this:

          set HTTP_proxy=my.proxy.com:3128

  4. Start the PPM program:

          C:\> C:\perl\bin\ppm.pl

  5. If you have not previously done so, install `DBI':

          ppm> install DBI

  6. If this succeeds, run the following command:

          ppm> install DBD-mysql

This procedure should work with ActiveState Perl 5.6 or newer.

If you cannot get the procedure to work, you should install the MyODBC
driver instead and connect to the MySQL server through ODBC:

     use DBI;
     $dbh= DBI->connect("DBI:ODBC:$dsn",$user,$password) ||
       die "Got error $DBI::errstr when connecting to $dsn\n";


File: manual.info,  Node: perl-support-problems,  Prev: activestate-perl,  Up: perl-support

2.15.3 Problems Using the Perl `DBI'/`DBD' Interface
----------------------------------------------------

If Perl reports that it cannot find the `../mysql/mysql.so' module, the
problem is probably that Perl cannot locate the `libmysqlclient.so'
shared library. You should be able to fix this problem by one of the
following methods:

   * Compile the `DBD::mysql' distribution with `perl Makefile.PL
     -static -config' rather than `perl Makefile.PL'.

   * Copy `libmysqlclient.so' to the directory where your other shared
     libraries are located (probably `/usr/lib' or `/lib').

   * Modify the `-L' options used to compile `DBD::mysql' to reflect
     the actual location of `libmysqlclient.so'.

   * On Linux, you can add the pathname of the directory where
     `libmysqlclient.so' is located to the `/etc/ld.so.conf' file.

   * Add the pathname of the directory where `libmysqlclient.so' is
     located to the `LD_RUN_PATH' environment variable. Some systems
     use `LD_LIBRARY_PATH' instead.

Note that you may also need to modify the `-L' options if there are
other libraries that the linker fails to find. For example, if the
linker cannot find `libc' because it is in `/lib' and the link command
specifies `-L/usr/lib', change the `-L' option to `-L/lib' or add
`-L/lib' to the existing link command.

If you get the following errors from `DBD::mysql', you are probably
using `gcc' (or using an old binary compiled with `gcc'):

     /usr/bin/perl: can't resolve symbol '__moddi3'
     /usr/bin/perl: can't resolve symbol '__divdi3'

Add `-L/usr/lib/gcc-lib/... -lgcc' to the link command when the
`mysql.so' library gets built (check the output from `make' for
`mysql.so' when you compile the Perl client).  The `-L' option should
specify the pathname of the directory where `libgcc.a' is located on
your system.

Another cause of this problem may be that Perl and MySQL are not both
compiled with `gcc'. In this case, you can solve the mismatch by
compiling both with `gcc'.

You may see the following error from `DBD::mysql' when you run the
tests:

     t/00base............install_driver(mysql) failed:
     Can't load '../blib/arch/auto/DBD/mysql/mysql.so' for module DBD::mysql:
     ../blib/arch/auto/DBD/mysql/mysql.so: undefined symbol:
     uncompress at /usr/lib/perl5/5.00503/i586-linux/DynaLoader.pm line 169.

This means that you need to include the `-lz' compression library on
the link line. That can be done by changing the following line in the
file `lib/DBD/mysql/Install.pm':

     $sysliblist .= " -lm";

Change that line to:

     $sysliblist .= " -lm -lz";

After this, you _must_ run `make realclean' and then proceed with the
installation from the beginning.

If you want to install DBI on SCO, you have to edit the `Makefile' in
DBI-XXX and each subdirectory. Note that the following assumes `gcc'
2.95.2 or newer:

     OLD:                                  NEW:
     CC = cc                               CC = gcc
     CCCDLFLAGS = -KPIC -W1,-Bexport       CCCDLFLAGS = -fpic
     CCDLFLAGS = -wl,-Bexport              CCDLFLAGS =

     LD = ld                               LD = gcc -G -fpic
     LDDLFLAGS = -G -L/usr/local/lib       LDDLFLAGS = -L/usr/local/lib
     LDFLAGS = -belf -L/usr/local/lib      LDFLAGS = -L/usr/local/lib

     LD = ld                               LD = gcc -G -fpic
     OPTIMISE = -Od                        OPTIMISE = -O1

     OLD:
     CCCFLAGS = -belf -dy -w0 -U M_XENIX -DPERL_SCO5 -I/usr/local/include

     NEW:
     CCFLAGS = -U M_XENIX -DPERL_SCO5 -I/usr/local/include

These changes are necessary because the Perl dynaloader does not load
the `DBI' modules if they were compiled with `icc' or `cc'.

If you want to use the Perl module on a system that does not support
dynamic linking (such as SCO), you can generate a static version of
Perl that includes `DBI' and `DBD::mysql'. The way this works is that
you generate a version of Perl with the `DBI' code linked in and
install it on top of your current Perl. Then you use that to build a
version of Perl that additionally has the `DBD' code linked in, and
install that.

On SCO, you must have the following environment variables set:

     LD_LIBRARY_PATH=/lib:/usr/lib:/usr/local/lib:/usr/progressive/lib

Or:

     LD_LIBRARY_PATH=/usr/lib:/lib:/usr/local/lib:/usr/ccs/lib:\
         /usr/progressive/lib:/usr/skunk/lib
     LIBPATH=/usr/lib:/lib:/usr/local/lib:/usr/ccs/lib:\
         /usr/progressive/lib:/usr/skunk/lib
     MANPATH=scohelp:/usr/man:/usr/local1/man:/usr/local/man:\
         /usr/skunk/man:

First, create a Perl that includes a statically linked `DBI' module by
running these commands in the directory where your `DBI' distribution is
located:

     shell> perl Makefile.PL -static -config
     shell> make
     shell> make install
     shell> make perl

Then you must install the new Perl. The output of `make perl' indicates
the exact `make' command you need to execute to perform the
installation. On SCO, this is `make -f Makefile.aperl inst_perl
MAP_TARGET=perl'.

Next, use the just-created Perl to create another Perl that also
includes a statically linked `DBD::mysql' by running these commands in
the directory where your `DBD::mysql' distribution is located:

     shell> perl Makefile.PL -static -config
     shell> make
     shell> make install
     shell> make perl

Finally, you should install this new Perl. Again, the output of `make
perl' indicates the command to use.


File: manual.info,  Node: tutorial,  Next: programs,  Prev: installing,  Up: Top

3 Tutorial
**********

* Menu:

* connecting-disconnecting::     Connecting to and Disconnecting from the Server
* entering-queries::             Entering Queries
* database-use::                 Creating and Using a Database
* getting-information::          Getting Information About Databases and Tables
* batch-mode::                   Using `mysql' in Batch Mode
* examples::                     Examples of Common Queries
* twin::                         Queries from the Twin Project
* apache::                       Using MySQL with Apache

This chapter provides a tutorial introduction to MySQL by showing how
to use the `mysql' client program to create and use a simple database.
`mysql' (sometimes referred to as the `terminal monitor' or just
`monitor') is an interactive program that allows you to connect to a
MySQL server, run queries, and view the results.  `mysql' may also be
used in batch mode: you place your queries in a file beforehand, then
tell `mysql' to execute the contents of the file. Both ways of using
`mysql' are covered here.

To see a list of options provided by `mysql', invoke it with the
`--help' option:

     shell> mysql --help

This chapter assumes that `mysql' is installed on your machine and that
a MySQL server is available to which you can connect. If this is not
true, contact your MySQL administrator. (If _you_ are the
administrator, you need to consult the relevant portions of this
manual, such as *Note server-administration::.)

This chapter describes the entire process of setting up and using a
database. If you are interested only in accessing an existing database,
you may want to skip over the sections that describe how to create the
database and the tables it contains.

Because this chapter is tutorial in nature, many details are
necessarily omitted. Consult the relevant sections of the manual for
more information on the topics covered here.


File: manual.info,  Node: connecting-disconnecting,  Next: entering-queries,  Prev: tutorial,  Up: tutorial

3.1 Connecting to and Disconnecting from the Server
===================================================

To connect to the server, you will usually need to provide a MySQL user
name when you invoke `mysql' and, most likely, a password. If the
server runs on a machine other than the one where you log in, you will
also need to specify a host name.  Contact your administrator to find
out what connection parameters you should use to connect (that is, what
host, user name, and password to use). Once you know the proper
parameters, you should be able to connect like this:

     shell> mysql -h HOST -u USER -p
     Enter password: ********

`host' and `user' represent the host name where your MySQL server is
running and the user name of your MySQL account. Substitute appropriate
values for your setup.  The `********' represents your password; enter
it when `mysql' displays the `Enter password:' prompt.

If that works, you should see some introductory information followed by
a `mysql>' prompt:

     shell> mysql -h HOST -u USER -p
     Enter password: ********
     Welcome to the MySQL monitor.  Commands end with ; or \g.
     Your MySQL connection id is 25338 to server version: 5.1.28-standard

     Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

     mysql>

The `mysql>' prompt tells you that `mysql' is ready for you to enter
commands.

If you are logging in on the same machine that MySQL is running on, you
can omit the host, and simply use the following:

     shell< mysql -u USER -p

If, when you attempt to log in, you get an error message such as `ERROR
2002 (HY000): Can't connect to local MySQL server through socket
'/tmp/mysql.sock' (2)', it means that that MySQL server daemon (Unix)
or service (Windows) is not running. Consult the administrator or see
the section of *Note installing:: that is appropriate to your operating
system.

For help with other problems often encountered when trying to log in,
see *Note common-errors::.

Some MySQL installations allow users to connect as the anonymous
(unnamed) user to the server running on the local host. If this is the
case on your machine, you should be able to connect to that server by
invoking `mysql' without any options:

     shell> mysql

After you have connected successfully, you can disconnect any time by
typing `QUIT' (or `\q') at the `mysql>' prompt:

     mysql> QUIT
     Bye

On Unix, you can also disconnect by pressing Control-D.

Most examples in the following sections assume that you are connected
to the server. They indicate this by the `mysql>' prompt.


File: manual.info,  Node: entering-queries,  Next: database-use,  Prev: connecting-disconnecting,  Up: tutorial

3.2 Entering Queries
====================

Make sure that you are connected to the server, as discussed in the
previous section. Doing so does not in itself select any database to
work with, but that's okay. At this point, it's more important to find
out a little about how to issue queries than to jump right in creating
tables, loading data into them, and retrieving data from them. This
section describes the basic principles of entering commands, using
several queries you can try out to familiarize yourself with how `mysql'
works.

Here's a simple command that asks the server to tell you its version
number and the current date. Type it in as shown here following the
`mysql>' prompt and press Enter:

     mysql> SELECT VERSION(), CURRENT_DATE;
     +-----------------+--------------+
     | VERSION()       | CURRENT_DATE |
     +-----------------+--------------+
     | 5.1.2-alpha-log | 2005-10-11   |
     +-----------------+--------------+
     1 row in set (0.01 sec)
     mysql>

This query illustrates several things about `mysql':

   * A command normally consists of an SQL statement followed by a
     semicolon. (There are some exceptions where a semicolon may be
     omitted. `QUIT', mentioned earlier, is one of them. We'll get to
     others later.)

   * When you issue a command, `mysql' sends it to the server for
     execution and displays the results, then prints another `mysql>'
     prompt to indicate that it is ready for another command.

   * `mysql' displays query output in tabular form (rows and columns).
     The first row contains labels for the columns. The rows following
     are the query results. Normally, column labels are the names of
     the columns you fetch from database tables. If you're retrieving
     the value of an expression rather than a table column (as in the
     example just shown), `mysql' labels the column using the
     expression itself.

   * `mysql' shows how many rows were returned and how long the query
     took to execute, which gives you a rough idea of server
     performance. These values are imprecise because they represent
     wall clock time (not CPU or machine time), and because they are
     affected by factors such as server load and network latency. (For
     brevity, the `rows in set' line is sometimes not shown in the
     remaining examples in this chapter.)

Keywords may be entered in any lettercase. The following queries are
equivalent:

     mysql> SELECT VERSION(), CURRENT_DATE;
     mysql> select version(), current_date;
     mysql> SeLeCt vErSiOn(), current_DATE;

Here's another query. It demonstrates that you can use `mysql' as a
simple calculator:

     mysql> SELECT SIN(PI()/4), (4+1)*5;
     +------------------+---------+
     | SIN(PI()/4)      | (4+1)*5 |
     +------------------+---------+
     | 0.70710678118655 |      25 |
     +------------------+---------+
     1 row in set (0.02 sec)

The queries shown thus far have been relatively short, single-line
statements. You can even enter multiple statements on a single line.
Just end each one with a semicolon:

     mysql> SELECT VERSION(); SELECT NOW();
     +-----------------+
     | VERSION()       |
     +-----------------+
     | 5.1.2-alpha-log |
     +-----------------+
     1 row in set (0.00 sec)

     +---------------------+
     | NOW()               |
     +---------------------+
     | 2005-10-11 15:15:00 |
     +---------------------+
     1 row in set (0.00 sec)

A command need not be given all on a single line, so lengthy commands
that require several lines are not a problem.  `mysql' determines where
your statement ends by looking for the terminating semicolon, not by
looking for the end of the input line. (In other words, `mysql' accepts
free-format input: it collects input lines but does not execute them
until it sees the semicolon.)

Here's a simple multiple-line statement:

     mysql> SELECT
         -> USER()
         -> ,
         -> CURRENT_DATE;
     +---------------+--------------+
     | USER()        | CURRENT_DATE |
     +---------------+--------------+
     | jon@localhost | 2005-10-11   |
     +---------------+--------------+

In this example, notice how the prompt changes from `mysql>' to `->'
after you enter the first line of a multiple-line query. This is how
`mysql' indicates that it has not yet seen a complete statement and is
waiting for the rest. The prompt is your friend, because it provides
valuable feedback. If you use that feedback, you can always be aware of
what `mysql' is waiting for.

If you decide you do not want to execute a command that you are in the
process of entering, cancel it by typing `\c':

     mysql> SELECT
         -> USER()
         -> \c
     mysql>

Here, too, notice the prompt. It switches back to `mysql>' after you
type `\c', providing feedback to indicate that `mysql' is ready for a
new command.

The following table shows each of the prompts you may see and
summarizes what they mean about the state that `mysql' is in:

*Prompt**Meaning*
`mysql>'Ready for new command.
`->'    Waiting for next line of multiple-line command.
`'>'    Waiting for next line, waiting for completion of a string
        that began with a single quote (``''').
`">'    Waiting for next line, waiting for completion of a string
        that began with a double quote (``"'').
``>'    Waiting for next line, waiting for completion of an
        identifier that began with a backtick (```'').
`/*>'   Waiting for next line, waiting for completion of a
        comment that began with `/*'.

Multiple-line statements commonly occur by accident when you intend to
issue a command on a single line, but forget the terminating semicolon.
In this case, `mysql' waits for more input:

     mysql> SELECT USER()
         ->

If this happens to you (you think you've entered a statement but the
only response is a `->' prompt), most likely `mysql' is waiting for the
semicolon. If you don't notice what the prompt is telling you, you
might sit there for a while before realizing what you need to do. Enter
a semicolon to complete the statement, and `mysql' executes it:

     mysql> SELECT USER()
         -> ;
     +---------------+
     | USER()        |
     +---------------+
     | jon@localhost |
     +---------------+

The `'>' and `">' prompts occur during string collection (another way
of saying that MySQL is waiting for completion of a string). In MySQL,
you can write strings surrounded by either ``''' or ``"'' characters
(for example, `'hello'' or `"goodbye"'), and `mysql' lets you enter
strings that span multiple lines. When you see a `'>' or `">' prompt,
it means that you have entered a line containing a string that begins
with a ``''' or ``"'' quote character, but have not yet entered the
matching quote that terminates the string. This often indicates that
you have inadvertently left out a quote character. For example:

     mysql> SELECT * FROM my_table WHERE name = 'Smith AND age < 30;
         '>

If you enter this `SELECT' statement, then press `Enter' and wait for
the result, nothing happens.  Instead of wondering why this query takes
so long, notice the clue provided by the `'>' prompt. It tells you that
`mysql' expects to see the rest of an unterminated string. (Do you see
the error in the statement? The string `'Smith' is missing the second
single quote mark.)

At this point, what do you do? The simplest thing is to cancel the
command. However, you cannot just type `\c' in this case, because
`mysql' interprets it as part of the string that it is collecting.
Instead, enter the closing quote character (so `mysql' knows you've
finished the string), then type `\c':

     mysql> SELECT * FROM my_table WHERE name = 'Smith AND age < 30;
         '> '\c
     mysql>

The prompt changes back to `mysql>', indicating that `mysql' is ready
for a new command.

The ``>' prompt is similar to the `'>' and `">' prompts, but indicates
that you have begun but not completed a backtick-quoted identifier.

It is important to know what the `'>', `">', and ``>' prompts signify,
because if you mistakenly enter an unterminated string, any further
lines you type appear to be ignored by `mysql' -- including a line
containing `QUIT'. This can be quite confusing, especially if you do
not know that you need to supply the terminating quote before you can
cancel the current command.


File: manual.info,  Node: database-use,  Next: getting-information,  Prev: entering-queries,  Up: tutorial

3.3 Creating and Using a Database
=================================

* Menu:

* creating-database::            Creating and Selecting a Database
* creating-tables::              Creating a Table
* loading-tables::               Loading Data into a Table
* retrieving-data::              Retrieving Information from a Table

Once you know how to enter commands, you are ready to access a database.

Suppose that you have several pets in your home (your menagerie) and
you would like to keep track of various types of information about
them. You can do so by creating tables to hold your data and loading
them with the desired information. Then you can answer different sorts
of questions about your animals by retrieving data from the tables.
This section shows you how to:

   * Create a database

   * Create a table

   * Load data into the table

   * Retrieve data from the table in various ways

   * Use multiple tables

The menagerie database is simple (deliberately), but it is not
difficult to think of real-world situations in which a similar type of
database might be used. For example, a database like this could be used
by a farmer to keep track of livestock, or by a veterinarian to keep
track of patient records. A menagerie distribution containing some of
the queries and sample data used in the following sections can be
obtained from the MySQL Web site.  It is available in both compressed
`tar' file and Zip formats at `http://dev.mysql.com/doc/'.

Use the `SHOW' statement to find out what databases currently exist on
the server:

     mysql> SHOW DATABASES;
     +----------+
     | Database |
     +----------+
     | mysql    |
     | test     |
     | tmp      |
     +----------+

The `mysql' database describes user access privileges. The `test'
database often is available as a workspace for users to try things out.

The list of databases displayed by the statement may be different on
your machine; `SHOW DATABASES' does not show databases that you have no
privileges for if you do not have the `SHOW DATABASES' privilege. See
*Note show-databases::.

If the `test' database exists, try to access it:

     mysql> USE test
     Database changed

Note that `USE', like `QUIT', does not require a semicolon. (You can
terminate such statements with a semicolon if you like; it does no
harm.) The `USE' statement is special in another way, too: it must be
given on a single line.

You can use the `test' database (if you have access to it) for the
examples that follow, but anything you create in that database can be
removed by anyone else with access to it. For this reason, you should
probably ask your MySQL administrator for permission to use a database
of your own.  Suppose that you want to call yours `menagerie'.  The
administrator needs to execute a command like this:

     mysql> GRANT ALL ON menagerie.* TO 'your_mysql_name'@'your_client_host';

where `your_mysql_name' is the MySQL user name assigned to you and
`your_client_host' is the host from which you connect to the server.


File: manual.info,  Node: creating-database,  Next: creating-tables,  Prev: database-use,  Up: database-use

3.3.1 Creating and Selecting a Database
---------------------------------------

If the administrator creates your database for you when setting up your
permissions, you can begin using it. Otherwise, you need to create it
yourself:

     mysql> CREATE DATABASE menagerie;

Under Unix, database names are case sensitive (unlike SQL keywords), so
you must always refer to your database as `menagerie', not as
`Menagerie', `MENAGERIE', or some other variant. This is also true for
table names. (Under Windows, this restriction does not apply, although
you must refer to databases and tables using the same lettercase
throughout a given query. However, for a variety of reasons, our
recommended best practice is always to use the same lettercase that was
used when the database was created.)

*Note*:

If you get an error such as `ERROR 1044 (42000): Access denied for user
'monty'@'localhost' to database 'menagerie'' when attempting to create
a database, this means that your user account does not have the
necessary privileges to do so. Discuss this with the administrator or
see *Note privilege-system::.

Creating a database does not select it for use; you must do that
explicitly. To make `menagerie' the current database, use this command:

     mysql> USE menagerie
     Database changed

Your database needs to be created only once, but you must select it for
use each time you begin a `mysql' session. You can do this by issuing a
`USE' statement as shown in the example. Alternatively, you can select
the database on the command line when you invoke `mysql'. Just specify
its name after any connection parameters that you might need to
provide. For example:

     shell> mysql -h HOST -u USER -p menagerie
     Enter password: ********

Note that `menagerie' in the command just shown is *not* your password.
If you want to supply your password on the command line after the `-p'
option, you must do so with no intervening space (for example, as
`-pmypassword', not as `-p mypassword'). However, putting your password
on the command line is not recommended, because doing so exposes it to
snooping by other users logged in on your machine.


File: manual.info,  Node: creating-tables,  Next: loading-tables,  Prev: creating-database,  Up: database-use

3.3.2 Creating a Table
----------------------

Creating the database is the easy part, but at this point it's empty,
as `SHOW TABLES' tells you:

     mysql> SHOW TABLES;
     Empty set (0.00 sec)

The harder part is deciding what the structure of your database should
be: what tables you need and what columns should be in each of them.

You want a table that contains a record for each of your pets.  This
can be called the `pet' table, and it should contain, as a bare
minimum, each animal's name. Because the name by itself is not very
interesting, the table should contain other information. For example,
if more than one person in your family keeps pets, you might want to
list each animal's owner. You might also want to record some basic
descriptive information such as species and sex.

How about age? That might be of interest, but it's not a good thing to
store in a database. Age changes as time passes, which means you'd have
to update your records often. Instead, it's better to store a fixed
value such as date of birth. Then, whenever you need age, you can
calculate it as the difference between the current date and the birth
date. MySQL provides functions for doing date arithmetic, so this is
not difficult.  Storing birth date rather than age has other
advantages, too:

   * You can use the database for tasks such as generating reminders
     for upcoming pet birthdays. (If you think this type of query is
     somewhat silly, note that it is the same question you might ask in
     the context of a business database to identify clients to whom you
     need to send out birthday greetings in the current week or month,
     for that computer-assisted personal touch.)

   * You can calculate age in relation to dates other than the current
     date. For example, if you store death date in the database, you
     can easily calculate how old a pet was when it died.

You can probably think of other types of information that would be
useful in the `pet' table, but the ones identified so far are
sufficient: name, owner, species, sex, birth, and death.

Use a `CREATE TABLE' statement to specify the layout of your table:

     mysql> CREATE TABLE pet (name VARCHAR(20), owner VARCHAR(20),
         -> species VARCHAR(20), sex CHAR(1), birth DATE, death DATE);

`VARCHAR' is a good choice for the `name', `owner', and `species'
columns because the column values vary in length. The lengths in those
column definitions need not all be the same, and need not be `20'. You
can normally pick any length from `1' to `65535', whatever seems most
reasonable to you.  If you make a poor choice and it turns out later
that you need a longer field, MySQL provides an `ALTER TABLE' statement.

Several types of values can be chosen to represent sex in animal
records, such as `'m'' and `'f'', or perhaps `'male'' and `'female''.
It is simplest to use the single characters `'m'' and `'f''.

The use of the `DATE' data type for the `birth' and `death' columns is
a fairly obvious choice.

Once you have created a table, `SHOW TABLES' should produce some output:

     mysql> SHOW TABLES;
     +---------------------+
     | Tables in menagerie |
     +---------------------+
     | pet                 |
     +---------------------+

To verify that your table was created the way you expected, use a
`DESCRIBE' statement:

     mysql> DESCRIBE pet;
     +---------+-------------+------+-----+---------+-------+
     | Field   | Type        | Null | Key | Default | Extra |
     +---------+-------------+------+-----+---------+-------+
     | name    | varchar(20) | YES  |     | NULL    |       |
     | owner   | varchar(20) | YES  |     | NULL    |       |
     | species | varchar(20) | YES  |     | NULL    |       |
     | sex     | char(1)     | YES  |     | NULL    |       |
     | birth   | date        | YES  |     | NULL    |       |
     | death   | date        | YES  |     | NULL    |       |
     +---------+-------------+------+-----+---------+-------+

You can use `DESCRIBE' any time, for example, if you forget the names
of the columns in your table or what types they have.

For more information about MySQL data types, see *Note data-types::.


File: manual.info,  Node: loading-tables,  Next: retrieving-data,  Prev: creating-tables,  Up: database-use

3.3.3 Loading Data into a Table
-------------------------------

After creating your table, you need to populate it. The `LOAD DATA' and
`INSERT' statements are useful for this.

Suppose that your pet records can be described as shown here.  (Observe
that MySQL expects dates in `'YYYY-MM-DD'' format; this may be different
from what you are used to.)

*name*  *owner* *species**sex**birth*        *death*
Fluffy  Harold  cat     f    1993-02-04     
Claws   Gwen    cat     m    1994-03-17     
Buffy   Harold  dog     f    1989-05-13     
Fang    Benny   dog     m    1990-08-27     
Bowser  Diane   dog     m    1979-08-31     1995-07-29
Chirpy  Gwen    bird    f    1998-09-11     
WhistlerGwen    bird         1997-12-09     
Slim    Benny   snake   m    1996-04-29     

Because you are beginning with an empty table, an easy way to populate
it is to create a text file containing a row for each of your animals,
then load the contents of the file into the table with a single
statement.

You could create a text file `pet.txt' containing one record per line,
with values separated by tabs, and given in the order in which the
columns were listed in the `CREATE TABLE' statement. For missing values
(such as unknown sexes or death dates for animals that are still
living), you can use `NULL' values. To represent these in your text
file, use `\N' (backslash, capital-N). For example, the record for
Whistler the bird would look like this (where the whitespace between
values is a single tab character):

     Whistler        Gwen    bird    \N      1997-12-09      \N

To load the text file `pet.txt' into the `pet' table, use this command:

     mysql> LOAD DATA LOCAL INFILE '/path/pet.txt' INTO TABLE pet;

Note that if you created the file on Windows with an editor that uses
`\r\n' as a line terminator, you should use:

     mysql> LOAD DATA LOCAL INFILE '/path/pet.txt' INTO TABLE pet
         -> LINES TERMINATED BY '\r\n';

(On an Apple machine running OS X, you would likely want to use `LINES
TERMINATED BY '\r''.)

You can specify the column value separator and end of line marker
explicitly in the `LOAD DATA' statement if you wish, but the defaults
are tab and linefeed. These are sufficient for the statement to read
the file `pet.txt' properly.

If the statement fails, it is likely that your MySQL installation does
not have local file capability enabled by default. See *Note
load-data-local::, for information on how to change this.

When you want to add new records one at a time, the `INSERT' statement
is useful. In its simplest form, you supply values for each column, in
the order in which the columns were listed in the `CREATE TABLE'
statement. Suppose that Diane gets a new hamster named `Puffball.' You
could add a new record using an `INSERT' statement like this:

     mysql> INSERT INTO pet
         -> VALUES ('Puffball','Diane','hamster','f','1999-03-30',NULL);

Note that string and date values are specified as quoted strings here.
Also, with `INSERT', you can insert `NULL' directly to represent a
missing value.  You do not use `\N' like you do with `LOAD DATA'.

From this example, you should be able to see that there would be a lot
more typing involved to load your records initially using several
`INSERT' statements rather than a single `LOAD DATA' statement.


File: manual.info,  Node: retrieving-data,  Prev: loading-tables,  Up: database-use

3.3.4 Retrieving Information from a Table
-----------------------------------------

* Menu:

* selecting-all::                Selecting All Data
* selecting-rows::               Selecting Particular Rows
* selecting-columns::            Selecting Particular Columns
* sorting-rows::                 Sorting Rows
* date-calculations::            Date Calculations
* working-with-null::            Working with `NULL' Values
* pattern-matching::             Pattern Matching
* counting-rows::                Counting Rows
* multiple-tables::              Using More Than one Table

The `SELECT' statement is used to pull information from a table. The
general form of the statement is:

     SELECT WHAT_TO_SELECT
     FROM WHICH_TABLE
     WHERE CONDITIONS_TO_SATISFY;

WHAT_TO_SELECT indicates what you want to see. This can be a list of
columns, or `*' to indicate `all columns.' WHICH_TABLE indicates the
table from which you want to retrieve data. The `WHERE' clause is
optional. If it is present, CONDITIONS_TO_SATISFY specifies one or more
conditions that rows must satisfy to qualify for retrieval.


File: manual.info,  Node: selecting-all,  Next: selecting-rows,  Prev: retrieving-data,  Up: retrieving-data

3.3.4.1 Selecting All Data
..........................

The simplest form of `SELECT' retrieves everything from a table:

     mysql> SELECT * FROM pet;
     +----------+--------+---------+------+------------+------------+
     | name     | owner  | species | sex  | birth      | death      |
     +----------+--------+---------+------+------------+------------+
     | Fluffy   | Harold | cat     | f    | 1993-02-04 | NULL       |
     | Claws    | Gwen   | cat     | m    | 1994-03-17 | NULL       |
     | Buffy    | Harold | dog     | f    | 1989-05-13 | NULL       |
     | Fang     | Benny  | dog     | m    | 1990-08-27 | NULL       |
     | Bowser   | Diane  | dog     | m    | 1979-08-31 | 1995-07-29 |
     | Chirpy   | Gwen   | bird    | f    | 1998-09-11 | NULL       |
     | Whistler | Gwen   | bird    | NULL | 1997-12-09 | NULL       |
     | Slim     | Benny  | snake   | m    | 1996-04-29 | NULL       |
     | Puffball | Diane  | hamster | f    | 1999-03-30 | NULL       |
     +----------+--------+---------+------+------------+------------+

This form of `SELECT' is useful if you want to review your entire
table, for example, after you've just loaded it with your initial data
set. For example, you may happen to think that the birth date for
Bowser doesn't seem quite right. Consulting your original pedigree
papers, you find that the correct birth year should be 1989, not 1979.

There are at least two ways to fix this:

   * Edit the file `pet.txt' to correct the error, then empty the table
     and reload it using `DELETE' and `LOAD DATA':

          mysql> DELETE FROM pet;
          mysql> LOAD DATA LOCAL INFILE 'pet.txt' INTO TABLE pet;

     However, if you do this, you must also re-enter the record for
     Puffball.

   * Fix only the erroneous record with an `UPDATE' statement:

          mysql> UPDATE pet SET birth = '1989-08-31' WHERE name = 'Bowser';

     The `UPDATE' changes only the record in question and does not
     require you to reload the table.


File: manual.info,  Node: selecting-rows,  Next: selecting-columns,  Prev: selecting-all,  Up: retrieving-data

3.3.4.2 Selecting Particular Rows
.................................

As shown in the preceding section, it is easy to retrieve an entire
table. Just omit the `WHERE' clause from the `SELECT' statement. But
typically you don't want to see the entire table, particularly when it
becomes large. Instead, you're usually more interested in answering a
particular question, in which case you specify some constraints on the
information you want. Let's look at some selection queries in terms of
questions about your pets that they answer.

You can select only particular rows from your table. For example, if
you want to verify the change that you made to Bowser's birth date,
select Bowser's record like this:

     mysql> SELECT * FROM pet WHERE name = 'Bowser';
     +--------+-------+---------+------+------------+------------+
     | name   | owner | species | sex  | birth      | death      |
     +--------+-------+---------+------+------------+------------+
     | Bowser | Diane | dog     | m    | 1989-08-31 | 1995-07-29 |
     +--------+-------+---------+------+------------+------------+

The output confirms that the year is correctly recorded as 1989, not
1979.

String comparisons normally are case-insensitive, so you can specify
the name as `'bowser'', `'BOWSER'', and so forth. The query result is
the same.

You can specify conditions on any column, not just `name'. For example,
if you want to know which animals were born during or after 1998, test
the `birth' column:

     mysql> SELECT * FROM pet WHERE birth >= '1998-1-1';
     +----------+-------+---------+------+------------+-------+
     | name     | owner | species | sex  | birth      | death |
     +----------+-------+---------+------+------------+-------+
     | Chirpy   | Gwen  | bird    | f    | 1998-09-11 | NULL  |
     | Puffball | Diane | hamster | f    | 1999-03-30 | NULL  |
     +----------+-------+---------+------+------------+-------+

You can combine conditions, for example, to locate female dogs:

     mysql> SELECT * FROM pet WHERE species = 'dog' AND sex = 'f';
     +-------+--------+---------+------+------------+-------+
     | name  | owner  | species | sex  | birth      | death |
     +-------+--------+---------+------+------------+-------+
     | Buffy | Harold | dog     | f    | 1989-05-13 | NULL  |
     +-------+--------+---------+------+------------+-------+

The preceding query uses the `AND' logical operator. There is also an
`OR' operator:

     mysql> SELECT * FROM pet WHERE species = 'snake' OR species = 'bird';
     +----------+-------+---------+------+------------+-------+
     | name     | owner | species | sex  | birth      | death |
     +----------+-------+---------+------+------------+-------+
     | Chirpy   | Gwen  | bird    | f    | 1998-09-11 | NULL  |
     | Whistler | Gwen  | bird    | NULL | 1997-12-09 | NULL  |
     | Slim     | Benny | snake   | m    | 1996-04-29 | NULL  |
     +----------+-------+---------+------+------------+-------+

`AND' and `OR' may be intermixed, although `AND' has higher precedence
than `OR'. If you use both operators, it is a good idea to use
parentheses to indicate explicitly how conditions should be grouped:

     mysql> SELECT * FROM pet WHERE (species = 'cat' AND sex = 'm')
         -> OR (species = 'dog' AND sex = 'f');
     +-------+--------+---------+------+------------+-------+
     | name  | owner  | species | sex  | birth      | death |
     +-------+--------+---------+------+------------+-------+
     | Claws | Gwen   | cat     | m    | 1994-03-17 | NULL  |
     | Buffy | Harold | dog     | f    | 1989-05-13 | NULL  |
     +-------+--------+---------+------+------------+-------+


File: manual.info,  Node: selecting-columns,  Next: sorting-rows,  Prev: selecting-rows,  Up: retrieving-data

3.3.4.3 Selecting Particular Columns
....................................

If you do not want to see entire rows from your table, just name the
columns in which you are interested, separated by commas. For example,
if you want to know when your animals were born, select the `name' and
`birth' columns:

     mysql> SELECT name, birth FROM pet;
     +----------+------------+
     | name     | birth      |
     +----------+------------+
     | Fluffy   | 1993-02-04 |
     | Claws    | 1994-03-17 |
     | Buffy    | 1989-05-13 |
     | Fang     | 1990-08-27 |
     | Bowser   | 1989-08-31 |
     | Chirpy   | 1998-09-11 |
     | Whistler | 1997-12-09 |
     | Slim     | 1996-04-29 |
     | Puffball | 1999-03-30 |
     +----------+------------+

To find out who owns pets, use this query:

     mysql> SELECT owner FROM pet;
     +--------+
     | owner  |
     +--------+
     | Harold |
     | Gwen   |
     | Harold |
     | Benny  |
     | Diane  |
     | Gwen   |
     | Gwen   |
     | Benny  |
     | Diane  |
     +--------+

Notice that the query simply retrieves the `owner' column from each
record, and some of them appear more than once. To minimize the output,
retrieve each unique output record just once by adding the keyword
`DISTINCT':

     mysql> SELECT DISTINCT owner FROM pet;
     +--------+
     | owner  |
     +--------+
     | Benny  |
     | Diane  |
     | Gwen   |
     | Harold |
     +--------+

You can use a `WHERE' clause to combine row selection with column
selection. For example, to get birth dates for dogs and cats only, use
this query:

     mysql> SELECT name, species, birth FROM pet
         -> WHERE species = 'dog' OR species = 'cat';
     +--------+---------+------------+
     | name   | species | birth      |
     +--------+---------+------------+
     | Fluffy | cat     | 1993-02-04 |
     | Claws  | cat     | 1994-03-17 |
     | Buffy  | dog     | 1989-05-13 |
     | Fang   | dog     | 1990-08-27 |
     | Bowser | dog     | 1989-08-31 |
     +--------+---------+------------+


File: manual.info,  Node: sorting-rows,  Next: date-calculations,  Prev: selecting-columns,  Up: retrieving-data

3.3.4.4 Sorting Rows
....................

You may have noticed in the preceding examples that the result rows are
displayed in no particular order. It's often easier to examine query
output when the rows are sorted in some meaningful way. To sort a
result, use an `ORDER BY' clause.

Here are animal birthdays, sorted by date:

     mysql> SELECT name, birth FROM pet ORDER BY birth;
     +----------+------------+
     | name     | birth      |
     +----------+------------+
     | Buffy    | 1989-05-13 |
     | Bowser   | 1989-08-31 |
     | Fang     | 1990-08-27 |
     | Fluffy   | 1993-02-04 |
     | Claws    | 1994-03-17 |
     | Slim     | 1996-04-29 |
     | Whistler | 1997-12-09 |
     | Chirpy   | 1998-09-11 |
     | Puffball | 1999-03-30 |
     +----------+------------+

On character type columns, sorting -- like all other comparison
operations -- is normally performed in a case-insensitive fashion. This
means that the order is undefined for columns that are identical except
for their case. You can force a case-sensitive sort for a column by
using `BINARY' like so: `ORDER BY BINARY COL_NAME'.

The default sort order is ascending, with smallest values first. To
sort in reverse (descending) order, add the `DESC' keyword to the name
of the column you are sorting by:

     mysql> SELECT name, birth FROM pet ORDER BY birth DESC;
     +----------+------------+
     | name     | birth      |
     +----------+------------+
     | Puffball | 1999-03-30 |
     | Chirpy   | 1998-09-11 |
     | Whistler | 1997-12-09 |
     | Slim     | 1996-04-29 |
     | Claws    | 1994-03-17 |
     | Fluffy   | 1993-02-04 |
     | Fang     | 1990-08-27 |
     | Bowser   | 1989-08-31 |
     | Buffy    | 1989-05-13 |
     +----------+------------+

You can sort on multiple columns, and you can sort different columns in
different directions. For example, to sort by type of animal in
ascending order, then by birth date within animal type in descending
order (youngest animals first), use the following query:

     mysql> SELECT name, species, birth FROM pet
         -> ORDER BY species, birth DESC;
     +----------+---------+------------+
     | name     | species | birth      |
     +----------+---------+------------+
     | Chirpy   | bird    | 1998-09-11 |
     | Whistler | bird    | 1997-12-09 |
     | Claws    | cat     | 1994-03-17 |
     | Fluffy   | cat     | 1993-02-04 |
     | Fang     | dog     | 1990-08-27 |
     | Bowser   | dog     | 1989-08-31 |
     | Buffy    | dog     | 1989-05-13 |
     | Puffball | hamster | 1999-03-30 |
     | Slim     | snake   | 1996-04-29 |
     +----------+---------+------------+

Note that the `DESC' keyword applies only to the column name
immediately preceding it (`birth'); it does not affect the `species'
column sort order.


File: manual.info,  Node: date-calculations,  Next: working-with-null,  Prev: sorting-rows,  Up: retrieving-data

3.3.4.5 Date Calculations
.........................

MySQL provides several functions that you can use to perform
calculations on dates, for example, to calculate ages or extract parts
of dates.

To determine how many years old each of your pets is, compute the
difference in the year part of the current date and the birth date,
then subtract one if the current date occurs earlier in the calendar
year than the birth date. The following query shows, for each pet, the
birth date, the current date, and the age in years.

     mysql> SELECT name, birth, CURDATE(),
         -> (YEAR(CURDATE())-YEAR(birth))
         -> - (RIGHT(CURDATE(),5)<RIGHT(birth,5))
         -> AS age
         -> FROM pet;
     +----------+------------+------------+------+
     | name     | birth      | CURDATE()  | age  |
     +----------+------------+------------+------+
     | Fluffy   | 1993-02-04 | 2003-08-19 |   10 |
     | Claws    | 1994-03-17 | 2003-08-19 |    9 |
     | Buffy    | 1989-05-13 | 2003-08-19 |   14 |
     | Fang     | 1990-08-27 | 2003-08-19 |   12 |
     | Bowser   | 1989-08-31 | 2003-08-19 |   13 |
     | Chirpy   | 1998-09-11 | 2003-08-19 |    4 |
     | Whistler | 1997-12-09 | 2003-08-19 |    5 |
     | Slim     | 1996-04-29 | 2003-08-19 |    7 |
     | Puffball | 1999-03-30 | 2003-08-19 |    4 |
     +----------+------------+------------+------+

Here, `YEAR()' pulls out the year part of a date and `RIGHT()' pulls
off the rightmost five characters that represent the `MM-DD' (calendar
year) part of the date. The part of the expression that compares the
`MM-DD' values evaluates to 1 or 0, which adjusts the year difference
down a year if `CURDATE()' occurs earlier in the year than `birth'. The
full expression is somewhat ungainly, so an _alias_ (`age') is used to
make the output column label more meaningful.

The query works, but the result could be scanned more easily if the
rows were presented in some order. This can be done by adding an `ORDER
BY name' clause to sort the output by name:

     mysql> SELECT name, birth, CURDATE(),
         -> (YEAR(CURDATE())-YEAR(birth))
         -> - (RIGHT(CURDATE(),5)<RIGHT(birth,5))
         -> AS age
         -> FROM pet ORDER BY name;
     +----------+------------+------------+------+
     | name     | birth      | CURDATE()  | age  |
     +----------+------------+------------+------+
     | Bowser   | 1989-08-31 | 2003-08-19 |   13 |
     | Buffy    | 1989-05-13 | 2003-08-19 |   14 |
     | Chirpy   | 1998-09-11 | 2003-08-19 |    4 |
     | Claws    | 1994-03-17 | 2003-08-19 |    9 |
     | Fang     | 1990-08-27 | 2003-08-19 |   12 |
     | Fluffy   | 1993-02-04 | 2003-08-19 |   10 |
     | Puffball | 1999-03-30 | 2003-08-19 |    4 |
     | Slim     | 1996-04-29 | 2003-08-19 |    7 |
     | Whistler | 1997-12-09 | 2003-08-19 |    5 |
     +----------+------------+------------+------+

To sort the output by `age' rather than `name', just use a different
`ORDER BY' clause:

     mysql> SELECT name, birth, CURDATE(),
         -> (YEAR(CURDATE())-YEAR(birth))
         -> - (RIGHT(CURDATE(),5)<RIGHT(birth,5))
         -> AS age
         -> FROM pet ORDER BY age;
     +----------+------------+------------+------+
     | name     | birth      | CURDATE()  | age  |
     +----------+------------+------------+------+
     | Chirpy   | 1998-09-11 | 2003-08-19 |    4 |
     | Puffball | 1999-03-30 | 2003-08-19 |    4 |
     | Whistler | 1997-12-09 | 2003-08-19 |    5 |
     | Slim     | 1996-04-29 | 2003-08-19 |    7 |
     | Claws    | 1994-03-17 | 2003-08-19 |    9 |
     | Fluffy   | 1993-02-04 | 2003-08-19 |   10 |
     | Fang     | 1990-08-27 | 2003-08-19 |   12 |
     | Bowser   | 1989-08-31 | 2003-08-19 |   13 |
     | Buffy    | 1989-05-13 | 2003-08-19 |   14 |
     +----------+------------+------------+------+

A similar query can be used to determine age at death for animals that
have died. You determine which animals these are by checking whether
the `death' value is `NULL'. Then, for those with non-`NULL' values,
compute the difference between the `death' and `birth' values:

     mysql> SELECT name, birth, death,
         -> (YEAR(death)-YEAR(birth)) - (RIGHT(death,5)<RIGHT(birth,5))
         -> AS age
         -> FROM pet WHERE death IS NOT NULL ORDER BY age;
     +--------+------------+------------+------+
     | name   | birth      | death      | age  |
     +--------+------------+------------+------+
     | Bowser | 1989-08-31 | 1995-07-29 |    5 |
     +--------+------------+------------+------+

The query uses `death IS NOT NULL' rather than `death <> NULL' because
`NULL' is a special value that cannot be compared using the usual
comparison operators. This is discussed later. See *Note
working-with-null::.

What if you want to know which animals have birthdays next month? For
this type of calculation, year and day are irrelevant; you simply want
to extract the month part of the `birth' column. MySQL provides several
functions for extracting parts of dates, such as `YEAR()', `MONTH()',
and `DAYOFMONTH()'.  `MONTH()' is the appropriate function here. To see
how it works, run a simple query that displays the value of both
`birth' and `MONTH(birth)':

     mysql> SELECT name, birth, MONTH(birth) FROM pet;
     +----------+------------+--------------+
     | name     | birth      | MONTH(birth) |
     +----------+------------+--------------+
     | Fluffy   | 1993-02-04 |            2 |
     | Claws    | 1994-03-17 |            3 |
     | Buffy    | 1989-05-13 |            5 |
     | Fang     | 1990-08-27 |            8 |
     | Bowser   | 1989-08-31 |            8 |
     | Chirpy   | 1998-09-11 |            9 |
     | Whistler | 1997-12-09 |           12 |
     | Slim     | 1996-04-29 |            4 |
     | Puffball | 1999-03-30 |            3 |
     +----------+------------+--------------+

Finding animals with birthdays in the upcoming month is also simple.
Suppose that the current month is April. Then the month value is `4'
and you can look for animals born in May (month `5') like this:

     mysql> SELECT name, birth FROM pet WHERE MONTH(birth) = 5;
     +-------+------------+
     | name  | birth      |
     +-------+------------+
     | Buffy | 1989-05-13 |
     +-------+------------+

There is a small complication if the current month is December. You
cannot merely add one to the month number (`12') and look for animals
born in month `13', because there is no such month.  Instead, you look
for animals born in January (month `1').

You can write the query so that it works no matter what the current
month is, so that you do not have to use the number for a particular
month.  `DATE_ADD()' allows you to add a time interval to a given date.
If you add a month to the value of `CURDATE()', then extract the month
part with `MONTH()', the result produces the month in which to look for
birthdays:

     mysql> SELECT name, birth FROM pet
         -> WHERE MONTH(birth) = MONTH(DATE_ADD(CURDATE(),INTERVAL 1 MONTH));

A different way to accomplish the same task is to add `1' to get the
next month after the current one after using the modulo function (`MOD')
to wrap the month value to `0' if it is currently `12':

     mysql> SELECT name, birth FROM pet
         -> WHERE MONTH(birth) = MOD(MONTH(CURDATE()), 12) + 1;

Note that `MONTH()' returns a number between `1' and `12'.  And
`MOD(something,12)' returns a number between `0' and `11'. So the
addition has to be after the `MOD()', otherwise we would go from
November (`11') to January (`1').


File: manual.info,  Node: working-with-null,  Next: pattern-matching,  Prev: date-calculations,  Up: retrieving-data

3.3.4.6 Working with `NULL' Values
..................................

The `NULL' value can be surprising until you get used to it.
Conceptually, `NULL' means `a missing unknown value' and it is treated
somewhat differently from other values. To test for `NULL', you cannot
use the arithmetic comparison operators such as `=', `<', or `<>'. To
demonstrate this for yourself, try the following query:

     mysql> SELECT 1 = NULL, 1 <> NULL, 1 < NULL, 1 > NULL;
     +----------+-----------+----------+----------+
     | 1 = NULL | 1 <> NULL | 1 < NULL | 1 > NULL |
     +----------+-----------+----------+----------+
     |     NULL |      NULL |     NULL |     NULL |
     +----------+-----------+----------+----------+

Clearly you get no meaningful results from these comparisons.  Use the
`IS NULL' and `IS NOT NULL' operators instead:

     mysql> SELECT 1 IS NULL, 1 IS NOT NULL;
     +-----------+---------------+
     | 1 IS NULL | 1 IS NOT NULL |
     +-----------+---------------+
     |         0 |             1 |
     +-----------+---------------+

Note that in MySQL, `0' or `NULL' means false and anything else means
true. The default truth value from a boolean operation is `1'.

This special treatment of `NULL' is why, in the previous section, it
was necessary to determine which animals are no longer alive using
`death IS NOT NULL' instead of `death <> NULL'.

Two `NULL' values are regarded as equal in a `GROUP BY'.

When doing an `ORDER BY', `NULL' values are presented first if you do
`ORDER BY ... ASC' and last if you do `ORDER BY ... DESC'.

A common error when working with `NULL' is to assume that it is not
possible to insert a zero or an empty string into a column defined as
`NOT NULL', but this is not the case. These are in fact values, whereas
`NULL' means `not having a value.' You can test this easily enough by
using `IS '[`NOT']` NULL' as shown:

     mysql> SELECT 0 IS NULL, 0 IS NOT NULL, '' IS NULL, '' IS NOT NULL;
     +-----------+---------------+------------+----------------+
     | 0 IS NULL | 0 IS NOT NULL | '' IS NULL | '' IS NOT NULL |
     +-----------+---------------+------------+----------------+
     |         0 |             1 |          0 |              1 |
     +-----------+---------------+------------+----------------+

Thus it is entirely possible to insert a zero or empty string into a
`NOT NULL' column, as these are in fact `NOT NULL'. See *Note
problems-with-null::.


File: manual.info,  Node: pattern-matching,  Next: counting-rows,  Prev: working-with-null,  Up: retrieving-data

3.3.4.7 Pattern Matching
........................

MySQL provides standard SQL pattern matching as well as a form of
pattern matching based on extended regular expressions similar to those
used by Unix utilities such as `vi', `grep', and `sed'.

SQL pattern matching allows you to use ``_'' to match any single
character and ``%'' to match an arbitrary number of characters
(including zero characters). In MySQL, SQL patterns are
case-insensitive by default. Some examples are shown here. Note that
you do not use `=' or `<>' when you use SQL patterns; use the `LIKE' or
`NOT LIKE' comparison operators instead.

To find names beginning with ``b'':

     mysql> SELECT * FROM pet WHERE name LIKE 'b%';
     +--------+--------+---------+------+------------+------------+
     | name   | owner  | species | sex  | birth      | death      |
     +--------+--------+---------+------+------------+------------+
     | Buffy  | Harold | dog     | f    | 1989-05-13 | NULL       |
     | Bowser | Diane  | dog     | m    | 1989-08-31 | 1995-07-29 |
     +--------+--------+---------+------+------------+------------+

To find names ending with ``fy'':

     mysql> SELECT * FROM pet WHERE name LIKE '%fy';
     +--------+--------+---------+------+------------+-------+
     | name   | owner  | species | sex  | birth      | death |
     +--------+--------+---------+------+------------+-------+
     | Fluffy | Harold | cat     | f    | 1993-02-04 | NULL  |
     | Buffy  | Harold | dog     | f    | 1989-05-13 | NULL  |
     +--------+--------+---------+------+------------+-------+

To find names containing a ``w'':

     mysql> SELECT * FROM pet WHERE name LIKE '%w%';
     +----------+-------+---------+------+------------+------------+
     | name     | owner | species | sex  | birth      | death      |
     +----------+-------+---------+------+------------+------------+
     | Claws    | Gwen  | cat     | m    | 1994-03-17 | NULL       |
     | Bowser   | Diane | dog     | m    | 1989-08-31 | 1995-07-29 |
     | Whistler | Gwen  | bird    | NULL | 1997-12-09 | NULL       |
     +----------+-------+---------+------+------------+------------+

To find names containing exactly five characters, use five instances of
the ``_'' pattern character:

     mysql> SELECT * FROM pet WHERE name LIKE '_____';
     +-------+--------+---------+------+------------+-------+
     | name  | owner  | species | sex  | birth      | death |
     +-------+--------+---------+------+------------+-------+
     | Claws | Gwen   | cat     | m    | 1994-03-17 | NULL  |
     | Buffy | Harold | dog     | f    | 1989-05-13 | NULL  |
     +-------+--------+---------+------+------------+-------+

The other type of pattern matching provided by MySQL uses extended
regular expressions. When you test for a match for this type of
pattern, use the `REGEXP' and `NOT REGEXP' operators (or `RLIKE' and
`NOT RLIKE', which are synonyms).

Some characteristics of extended regular expressions are:

   * ``.'' matches any single character.

   * A character class ``[...]'' matches any character within the
     brackets. For example, ``[abc]'' matches ``a'', ``b'', or ``c''.
     To name a range of characters, use a dash.  ``[a-z]'' matches any
     letter, whereas ``[0-9]'' matches any digit.

   * ``*'' matches zero or more instances of the thing preceding it.
     For example, ``x*'' matches any number of ``x'' characters,
     ``[0-9]*'' matches any number of digits, and ``.*'' matches any
     number of anything.

   * A `REGEXP' pattern match succeeds if the pattern matches anywhere
     in the value being tested. (This differs from a `LIKE' pattern
     match, which succeeds only if the pattern matches the entire
     value.)

   * To anchor a pattern so that it must match the beginning or end of
     the value being tested, use ``^'' at the beginning or ``$'' at the
     end of the pattern.

To demonstrate how extended regular expressions work, the `LIKE'
queries shown previously are rewritten here to use `REGEXP'.

To find names beginning with ``b'', use ``^'' to match the beginning of
the name:

     mysql> SELECT * FROM pet WHERE name REGEXP '^b';
     +--------+--------+---------+------+------------+------------+
     | name   | owner  | species | sex  | birth      | death      |
     +--------+--------+---------+------+------------+------------+
     | Buffy  | Harold | dog     | f    | 1989-05-13 | NULL       |
     | Bowser | Diane  | dog     | m    | 1989-08-31 | 1995-07-29 |
     +--------+--------+---------+------+------------+------------+

If you really want to force a `REGEXP' comparison to be case sensitive,
use the `BINARY' keyword to make one of the strings a binary string.
This query matches only lowercase ``b'' at the beginning of a name:

     mysql> SELECT * FROM pet WHERE name REGEXP BINARY '^b';

To find names ending with ``fy'', use ``$'' to match the end of the
name:

     mysql> SELECT * FROM pet WHERE name REGEXP 'fy$';
     +--------+--------+---------+------+------------+-------+
     | name   | owner  | species | sex  | birth      | death |
     +--------+--------+---------+------+------------+-------+
     | Fluffy | Harold | cat     | f    | 1993-02-04 | NULL  |
     | Buffy  | Harold | dog     | f    | 1989-05-13 | NULL  |
     +--------+--------+---------+------+------------+-------+

To find names containing a ``w'', use this query:

     mysql> SELECT * FROM pet WHERE name REGEXP 'w';
     +----------+-------+---------+------+------------+------------+
     | name     | owner | species | sex  | birth      | death      |
     +----------+-------+---------+------+------------+------------+
     | Claws    | Gwen  | cat     | m    | 1994-03-17 | NULL       |
     | Bowser   | Diane | dog     | m    | 1989-08-31 | 1995-07-29 |
     | Whistler | Gwen  | bird    | NULL | 1997-12-09 | NULL       |
     +----------+-------+---------+------+------------+------------+

Because a regular expression pattern matches if it occurs anywhere in
the value, it is not necessary in the previous query to put a wildcard
on either side of the pattern to get it to match the entire value like
it would be if you used an SQL pattern.

To find names containing exactly five characters, use ``^'' and ``$''
to match the beginning and end of the name, and five instances of ``.''
in between:

     mysql> SELECT * FROM pet WHERE name REGEXP '^.....$';
     +-------+--------+---------+------+------------+-------+
     | name  | owner  | species | sex  | birth      | death |
     +-------+--------+---------+------+------------+-------+
     | Claws | Gwen   | cat     | m    | 1994-03-17 | NULL  |
     | Buffy | Harold | dog     | f    | 1989-05-13 | NULL  |
     +-------+--------+---------+------+------------+-------+

You could also write the previous query using the `{N}'
(`repeat-N-times') operator:

     mysql> SELECT * FROM pet WHERE name REGEXP '^.{5}$';
     +-------+--------+---------+------+------------+-------+
     | name  | owner  | species | sex  | birth      | death |
     +-------+--------+---------+------+------------+-------+
     | Claws | Gwen   | cat     | m    | 1994-03-17 | NULL  |
     | Buffy | Harold | dog     | f    | 1989-05-13 | NULL  |
     +-------+--------+---------+------+------------+-------+

*Note regexp::, provides more information about the syntax for regular
expressions.


File: manual.info,  Node: counting-rows,  Next: multiple-tables,  Prev: pattern-matching,  Up: retrieving-data

3.3.4.8 Counting Rows
.....................

Databases are often used to answer the question, `How often does a
certain type of data occur in a table?' For example, you might want to
know how many pets you have, or how many pets each owner has, or you
might want to perform various kinds of census operations on your
animals.

Counting the total number of animals you have is the same question as
`How many rows are in the `pet' table?' because there is one record per
pet. `COUNT(*)' counts the number of rows, so the query to count your
animals looks like this:

     mysql> SELECT COUNT(*) FROM pet;
     +----------+
     | COUNT(*) |
     +----------+
     |        9 |
     +----------+

Earlier, you retrieved the names of the people who owned pets.  You can
use `COUNT()' if you want to find out how many pets each owner has:

     mysql> SELECT owner, COUNT(*) FROM pet GROUP BY owner;
     +--------+----------+
     | owner  | COUNT(*) |
     +--------+----------+
     | Benny  |        2 |
     | Diane  |        2 |
     | Gwen   |        3 |
     | Harold |        2 |
     +--------+----------+

Note the use of `GROUP BY' to group all records for each `owner'.
Without it, all you get is an error message:

     mysql> SELECT owner, COUNT(*) FROM pet;
     ERROR 1140 (42000): Mixing of GROUP columns (MIN(),MAX(),COUNT(),...)
     with no GROUP columns is illegal if there is no GROUP BY clause

`COUNT()' and `GROUP BY' are useful for characterizing your data in
various ways. The following examples show different ways to perform
animal census operations.

Number of animals per species:

     mysql> SELECT species, COUNT(*) FROM pet GROUP BY species;
     +---------+----------+
     | species | COUNT(*) |
     +---------+----------+
     | bird    |        2 |
     | cat     |        2 |
     | dog     |        3 |
     | hamster |        1 |
     | snake   |        1 |
     +---------+----------+

Number of animals per sex:

     mysql> SELECT sex, COUNT(*) FROM pet GROUP BY sex;
     +------+----------+
     | sex  | COUNT(*) |
     +------+----------+
     | NULL |        1 |
     | f    |        4 |
     | m    |        4 |
     +------+----------+

(In this output, `NULL' indicates that the sex is unknown.)

Number of animals per combination of species and sex:

     mysql> SELECT species, sex, COUNT(*) FROM pet GROUP BY species, sex;
     +---------+------+----------+
     | species | sex  | COUNT(*) |
     +---------+------+----------+
     | bird    | NULL |        1 |
     | bird    | f    |        1 |
     | cat     | f    |        1 |
     | cat     | m    |        1 |
     | dog     | f    |        1 |
     | dog     | m    |        2 |
     | hamster | f    |        1 |
     | snake   | m    |        1 |
     +---------+------+----------+

You need not retrieve an entire table when you use `COUNT()'. For
example, the previous query, when performed just on dogs and cats, looks
like this:

     mysql> SELECT species, sex, COUNT(*) FROM pet
         -> WHERE species = 'dog' OR species = 'cat'
         -> GROUP BY species, sex;
     +---------+------+----------+
     | species | sex  | COUNT(*) |
     +---------+------+----------+
     | cat     | f    |        1 |
     | cat     | m    |        1 |
     | dog     | f    |        1 |
     | dog     | m    |        2 |
     +---------+------+----------+

Or, if you wanted the number of animals per sex only for animals whose
sex is known:

     mysql> SELECT species, sex, COUNT(*) FROM pet
         -> WHERE sex IS NOT NULL
         -> GROUP BY species, sex;
     +---------+------+----------+
     | species | sex  | COUNT(*) |
     +---------+------+----------+
     | bird    | f    |        1 |
     | cat     | f    |        1 |
     | cat     | m    |        1 |
     | dog     | f    |        1 |
     | dog     | m    |        2 |
     | hamster | f    |        1 |
     | snake   | m    |        1 |
     +---------+------+----------+


File: manual.info,  Node: multiple-tables,  Prev: counting-rows,  Up: retrieving-data

3.3.4.9 Using More Than one Table
.................................

The `pet' table keeps track of which pets you have. If you want to
record other information about them, such as events in their lives like
visits to the vet or when litters are born, you need another table.
What should this table look like? It needs:

   * To contain the pet name so that you know which animal each event
     pertains to.

   * A date so that you know when the event occurred.

   * A field to describe the event.

   * An event type field, if you want to be able to categorize events.

Given these considerations, the `CREATE TABLE' statement for the `event'
table might look like this:

     mysql> CREATE TABLE event (name VARCHAR(20), date DATE,
         -> type VARCHAR(15), remark VARCHAR(255));

As with the `pet' table, it's easiest to load the initial records by
creating a tab-delimited text file containing the information:

*name*      *date*      *type*      *remark*
Fluffy      1995-05-15  litter      4 kittens, 3 female, 1
                                    male
Buffy       1993-06-23  litter      5 puppies, 2 female, 3
                                    male
Buffy       1994-06-19  litter      3 puppies, 3 female
Chirpy      1999-03-21  vet         needed beak straightened
Slim        1997-08-03  vet         broken rib
Bowser      1991-10-12  kennel      
Fang        1991-10-12  kennel      
Fang        1998-08-28  birthday    Gave him a new chew toy
Claws       1998-03-17  birthday    Gave him a new flea
                                    collar
Whistler    1998-12-09  birthday    First birthday

Load the records like this:

     mysql> LOAD DATA LOCAL INFILE 'event.txt' INTO TABLE event;

Based on what you have learned from the queries that you have run on
the `pet' table, you should be able to perform retrievals on the
records in the `event' table; the principles are the same.  But when is
the `event' table by itself insufficient to answer questions you might
ask?

Suppose that you want to find out the ages at which each pet had its
litters. We saw earlier how to calculate ages from two dates. The
litter date of the mother is in the `event' table, but to calculate her
age on that date you need her birth date, which is stored in the `pet'
table. This means the query requires both tables:

     mysql> SELECT pet.name,
         -> (YEAR(date)-YEAR(birth)) - (RIGHT(date,5)<RIGHT(birth,5)) AS age,
         -> remark
         -> FROM pet INNER JOIN event
         ->   ON pet.name = event.name
         -> WHERE event.type = 'litter';
     +--------+------+-----------------------------+
     | name   | age  | remark                      |
     +--------+------+-----------------------------+
     | Fluffy |    2 | 4 kittens, 3 female, 1 male |
     | Buffy  |    4 | 5 puppies, 2 female, 3 male |
     | Buffy  |    5 | 3 puppies, 3 female         |
     +--------+------+-----------------------------+

There are several things to note about this query:

   * The `FROM' clause joins two tables because the query needs to pull
     information from both of them.

   * When combining (joining) information from multiple tables, you
     need to specify how records in one table can be matched to records
     in the other. This is easy because they both have a `name' column.
     The query uses an `ON' clause to match up records in the two
     tables based on the `name' values.

     The query uses an `INNER JOIN' to combine the tables. An `INNER
     JOIN' allows for rows from either table to appear in the result if
     and only if both tables meet the conditions specified in the `ON'
     clause. In this example, the `ON' clause specifies that the `name'
     column in the `pet' table must match the `name' column in the
     `event' table. If a name appears in one table but not the other,
     the row will not appear in the result because the condition in the
     `ON' clause fails.

   * Because the `name' column occurs in both tables, you must be
     specific about which table you mean when referring to the column.
     This is done by prepending the table name to the column name.

You need not have two different tables to perform a join.  Sometimes it
is useful to join a table to itself, if you want to compare records in
a table to other records in that same table. For example, to find
breeding pairs among your pets, you can join the `pet' table with
itself to produce candidate pairs of males and females of like species:

     mysql> SELECT p1.name, p1.sex, p2.name, p2.sex, p1.species
         -> FROM pet AS p1 INNER JOIN pet AS p2
         ->   ON p1.species = p2.species AND p1.sex = 'f' AND p2.sex = 'm';
     +--------+------+--------+------+---------+
     | name   | sex  | name   | sex  | species |
     +--------+------+--------+------+---------+
     | Fluffy | f    | Claws  | m    | cat     |
     | Buffy  | f    | Fang   | m    | dog     |
     | Buffy  | f    | Bowser | m    | dog     |
     +--------+------+--------+------+---------+

In this query, we specify aliases for the table name to refer to the
columns and keep straight which instance of the table each column
reference is associated with.


File: manual.info,  Node: getting-information,  Next: batch-mode,  Prev: database-use,  Up: tutorial

3.4 Getting Information About Databases and Tables
==================================================

What if you forget the name of a database or table, or what the
structure of a given table is (for example, what its columns are
called)? MySQL addresses this problem through several statements that
provide information about the databases and tables it supports.

You have previously seen `SHOW DATABASES', which lists the databases
managed by the server. To find out which database is currently
selected, use the `DATABASE()' function:

     mysql> SELECT DATABASE();
     +------------+
     | DATABASE() |
     +------------+
     | menagerie  |
     +------------+

If you have not yet selected any database, the result is `NULL'.

To find out what tables the default database contains (for example,
when you are not sure about the name of a table), use this command:

     mysql> SHOW TABLES;
     +---------------------+
     | Tables_in_menagerie |
     +---------------------+
     | event               |
     | pet                 |
     +---------------------+

The name of the column in the output produced by this statement is
always `Tables_in_DB_NAME', where DB_NAME is the name of the database.
See *Note show-tables::, for more information.

If you want to find out about the structure of a table, the `DESCRIBE'
command is useful; it displays information about each of a table's
columns:

     mysql> DESCRIBE pet;
     +---------+-------------+------+-----+---------+-------+
     | Field   | Type        | Null | Key | Default | Extra |
     +---------+-------------+------+-----+---------+-------+
     | name    | varchar(20) | YES  |     | NULL    |       |
     | owner   | varchar(20) | YES  |     | NULL    |       |
     | species | varchar(20) | YES  |     | NULL    |       |
     | sex     | char(1)     | YES  |     | NULL    |       |
     | birth   | date        | YES  |     | NULL    |       |
     | death   | date        | YES  |     | NULL    |       |
     +---------+-------------+------+-----+---------+-------+

`Field' indicates the column name, `Type' is the data type for the
column, `NULL' indicates whether the column can contain `NULL' values,
`Key' indicates whether the column is indexed, and `Default' specifies
the column's default value. `Extra' displays special information about
columns; for example, if a column was created with the `AUTO_INCREMENT'
option, this is shown here.

`DESC' is a short form of `DESCRIBE'. See *Note describe::, for more
information.

You can obtain the `CREATE TABLE' statement necessary to create an
existing table using the `SHOW CREATE TABLE' statement. See *Note
show-create-table::.

If you have indexes on a table, `SHOW INDEX FROM TBL_NAME' produces
information about them. See *Note show-index::, for more about this
statement.


File: manual.info,  Node: batch-mode,  Next: examples,  Prev: getting-information,  Up: tutorial

3.5 Using `mysql' in Batch Mode
===============================

In the previous sections, you used `mysql' interactively to enter
queries and view the results. You can also run `mysql' in batch mode.
To do this, put the commands you want to run in a file, then tell
`mysql' to read its input from the file:

     shell> mysql < BATCH-FILE

If you are running `mysql' under Windows and have some special
characters in the file that cause problems, you can do this:

     C:\> mysql -e "source BATCH-FILE"

If you need to specify connection parameters on the command line, the
command might look like this:

     shell> mysql -h HOST -u USER -p < BATCH-FILE
     Enter password: ********

When you use `mysql' this way, you are creating a script file, then
executing the script.

If you want the script to continue even if some of the statements in it
produce errors, you should use the `--force' command-line option.

Why use a script? Here are a few reasons:

   * If you run a query repeatedly (say, every day or every week),
     making it a script allows you to avoid retyping it each time you
     execute it.

   * You can generate new queries from existing ones that are similar
     by copying and editing script files.

   * Batch mode can also be useful while you're developing a query,
     particularly for multiple-line commands or multiple-statement
     sequences of commands. If you make a mistake, you don't have to
     retype everything. Just edit your script to correct the error,
     then tell `mysql' to execute it again.

   * If you have a query that produces a lot of output, you can run the
     output through a pager rather than watching it scroll off the top
     of your screen:

          shell> mysql < BATCH-FILE | more

   * You can catch the output in a file for further processing:

          shell> mysql < BATCH-FILE > mysql.out

   * You can distribute your script to other people so that they can
     also run the commands.

   * Some situations do not allow for interactive use, for example,
     when you run a query from a `cron' job. In this case, you must use
     batch mode.

The default output format is different (more concise) when you run
`mysql' in batch mode than when you use it interactively. For example,
the output of `SELECT DISTINCT species FROM pet' looks like this when
`mysql' is run interactively:

     +---------+
     | species |
     +---------+
     | bird    |
     | cat     |
     | dog     |
     | hamster |
     | snake   |
     +---------+

In batch mode, the output looks like this instead:

     species
     bird
     cat
     dog
     hamster
     snake

If you want to get the interactive output format in batch mode, use
`mysql -t'. To echo to the output the commands that are executed, use
`mysql -vvv'.

You can also use scripts from the `mysql' prompt by using the `source'
command or `\.' command:

     mysql> source FILENAME;
     mysql> \. FILENAME

See *Note batch-commands::, for more information.


File: manual.info,  Node: examples,  Next: twin,  Prev: batch-mode,  Up: tutorial

3.6 Examples of Common Queries
==============================

* Menu:

* example-maximum-column::       The Maximum Value for a Column
* example-maximum-row::          The Row Holding the Maximum of a Certain Column
* example-maximum-column-group::  Maximum of Column per Group
* example-maximum-column-group-row::  The Rows Holding the Group-wise Maximum of a Certain Field
* example-user-variables::       Using User-Defined Variables
* example-foreign-keys::         Using Foreign Keys
* searching-on-two-keys::        Searching on Two Keys
* calculating-days::             Calculating Visits Per Day
* example-auto-increment::       Using `AUTO_INCREMENT'

Here are examples of how to solve some common problems with MySQL.

Some of the examples use the table `shop' to hold the price of each
article (item number) for certain traders (dealers). Supposing that
each trader has a single fixed price per article, then (`article',
`dealer') is a primary key for the records.

Start the command-line tool `mysql' and select a database:

     shell> mysql YOUR-DATABASE-NAME

(In most MySQL installations, you can use the database named `test').

You can create and populate the example table with these statements:

     CREATE TABLE shop (
         article INT(4) UNSIGNED ZEROFILL DEFAULT '0000' NOT NULL,
         dealer  CHAR(20)                 DEFAULT ''     NOT NULL,
         price   DOUBLE(16,2)             DEFAULT '0.00' NOT NULL,
         PRIMARY KEY(article, dealer));
     INSERT INTO shop VALUES
         (1,'A',3.45),(1,'B',3.99),(2,'A',10.99),(3,'B',1.45),
         (3,'C',1.69),(3,'D',1.25),(4,'D',19.95);

After issuing the statements, the table should have the following
contents:

     SELECT * FROM shop;

     +---------+--------+-------+
     | article | dealer | price |
     +---------+--------+-------+
     |    0001 | A      |  3.45 |
     |    0001 | B      |  3.99 |
     |    0002 | A      | 10.99 |
     |    0003 | B      |  1.45 |
     |    0003 | C      |  1.69 |
     |    0003 | D      |  1.25 |
     |    0004 | D      | 19.95 |
     +---------+--------+-------+


File: manual.info,  Node: example-maximum-column,  Next: example-maximum-row,  Prev: examples,  Up: examples

3.6.1 The Maximum Value for a Column
------------------------------------

`What's the highest item number?'

     SELECT MAX(article) AS article FROM shop;

     +---------+
     | article |
     +---------+
     |       4 |
     +---------+


File: manual.info,  Node: example-maximum-row,  Next: example-maximum-column-group,  Prev: example-maximum-column,  Up: examples

3.6.2 The Row Holding the Maximum of a Certain Column
-----------------------------------------------------

_Task: Find the number, dealer, and price of the most expensive
article._

This is easily done with a subquery:

     SELECT article, dealer, price
     FROM   shop
     WHERE  price=(SELECT MAX(price) FROM shop);

Another solution is to sort all rows descending by price and get only
the first row using the MySQL-specific `LIMIT' clause:

     SELECT article, dealer, price
     FROM shop
     ORDER BY price DESC
     LIMIT 1;

*Note*:

If there were several most expensive articles, each with a price of
19.95, the `LIMIT' solution would show only one of them.


File: manual.info,  Node: example-maximum-column-group,  Next: example-maximum-column-group-row,  Prev: example-maximum-row,  Up: examples

3.6.3 Maximum of Column per Group
---------------------------------

_Task: Find the highest price per article._

     SELECT article, MAX(price) AS price
     FROM   shop
     GROUP BY article;

     +---------+-------+
     | article | price |
     +---------+-------+
     |    0001 |  3.99 |
     |    0002 | 10.99 |
     |    0003 |  1.69 |
     |    0004 | 19.95 |
     +---------+-------+


File: manual.info,  Node: example-maximum-column-group-row,  Next: example-user-variables,  Prev: example-maximum-column-group,  Up: examples

3.6.4 The Rows Holding the Group-wise Maximum of a Certain Field
----------------------------------------------------------------

_Task: For each article, find the dealer or dealers with the most
expensive price._

This problem can be solved with a subquery like this one:

     SELECT article, dealer, price
     FROM   shop s1
     WHERE  price=(SELECT MAX(s2.price)
                   FROM shop s2
                   WHERE s1.article = s2.article);

     +---------+--------+-------+
     | article | dealer | price |
     +---------+--------+-------+
     |    0001 | B      |  3.99 |
     |    0002 | A      | 10.99 |
     |    0003 | C      |  1.69 |
     |    0004 | D      | 19.95 |
     +---------+--------+-------+

The preceding example uses a correlated subquery, which can be
inefficient (see *Note correlated-subqueries::). Other possibilities
for solving the problem are to use a uncorrelated subquery in the
`FROM' clause or a `LEFT JOIN':

     SELECT s1.article, dealer, s1.price
     FROM shop s1
     JOIN (
       SELECT article, MAX(price) AS price
       FROM shop
       GROUP BY article) AS s2
       ON s1.article = s2.article AND s1.price = s2.price;

     SELECT s1.article, s1.dealer, s1.price
     FROM shop s1
     LEFT JOIN shop s2 ON s1.article = s2.article AND s1.price < s2.price
     WHERE s2.article IS NULL;

The `LEFT JOIN' works on the basis that when `s1.price' is at its
maximum value, there is no `s2.price' with a greater value and the `s2'
rows values will be `NULL'. See *Note join::.


File: manual.info,  Node: example-user-variables,  Next: example-foreign-keys,  Prev: example-maximum-column-group-row,  Up: examples

3.6.5 Using User-Defined Variables
----------------------------------

You can employ MySQL user variables to remember results without having
to store them in temporary variables in the client. (See *Note
user-variables::.)

For example, to find the articles with the highest and lowest price you
can do this:

     mysql> SELECT @min_price:=MIN(price),@max_price:=MAX(price) FROM shop;
     mysql> SELECT * FROM shop WHERE price=@min_price OR price=@max_price;
     +---------+--------+-------+
     | article | dealer | price |
     +---------+--------+-------+
     |    0003 | D      |  1.25 |
     |    0004 | D      | 19.95 |
     +---------+--------+-------+

*Note*:

It is also possible to store the name of a database object such as a
table or a column in a user variable and then to use this variable in
an SQL statement; however, this requires the use of a prepared
statement. See *Note sql-syntax-prepared-statements::, for more
information.


File: manual.info,  Node: example-foreign-keys,  Next: searching-on-two-keys,  Prev: example-user-variables,  Up: examples

3.6.6 Using Foreign Keys
------------------------

In MySQL, `InnoDB' tables support checking of foreign key constraints.
See *Note innodb::, and *Note ansi-diff-foreign-keys::.

A foreign key constraint is not required merely to join two tables. For
storage engines other than `InnoDB', it is possible when defining a
column to use a `REFERENCES TBL_NAME(COL_NAME)' clause, which has no
actual effect, and _serves only as a memo or comment to you that the
column which you are currently defining is intended to refer to a
column in another table_. It is extremely important to realize when
using this syntax that:

   * MySQL does not perform any sort of `CHECK' to make sure that
     COL_NAME actually exists in TBL_NAME (or even that TBL_NAME itself
     exists).

   * MySQL does not perform any sort of action on TBL_NAME such as
     deleting rows in response to actions taken on rows in the table
     which you are defining; in other words, this syntax induces no `ON
     DELETE' or `ON UPDATE' behavior whatsoever. (Although you can
     write an `ON DELETE' or `ON UPDATE' clause as part of the
     `REFERENCES' clause, it is also ignored.)

   * This syntax creates a _column_; it does *not* create any sort of
     index or key.

   * This syntax will cause an error if used in trying to define an
     `InnoDB' table.

You can use a column so created as a join column, as shown here:

     CREATE TABLE person (
         id SMALLINT UNSIGNED NOT NULL AUTO_INCREMENT,
         name CHAR(60) NOT NULL,
         PRIMARY KEY (id)
     );

     CREATE TABLE shirt (
         id SMALLINT UNSIGNED NOT NULL AUTO_INCREMENT,
         style ENUM('t-shirt', 'polo', 'dress') NOT NULL,
         color ENUM('red', 'blue', 'orange', 'white', 'black') NOT NULL,
         owner SMALLINT UNSIGNED NOT NULL REFERENCES person(id),
         PRIMARY KEY (id)
     );

     INSERT INTO person VALUES (NULL, 'Antonio Paz');

     SELECT @last := LAST_INSERT_ID();

     INSERT INTO shirt VALUES
     (NULL, 'polo', 'blue', @last),
     (NULL, 'dress', 'white', @last),
     (NULL, 't-shirt', 'blue', @last);

     INSERT INTO person VALUES (NULL, 'Lilliana Angelovska');

     SELECT @last := LAST_INSERT_ID();

     INSERT INTO shirt VALUES
     (NULL, 'dress', 'orange', @last),
     (NULL, 'polo', 'red', @last),
     (NULL, 'dress', 'blue', @last),
     (NULL, 't-shirt', 'white', @last);

     SELECT * FROM person;
     +----+---------------------+
     | id | name                |
     +----+---------------------+
     |  1 | Antonio Paz         |
     |  2 | Lilliana Angelovska |
     +----+---------------------+

     SELECT * FROM shirt;
     +----+---------+--------+-------+
     | id | style   | color  | owner |
     +----+---------+--------+-------+
     |  1 | polo    | blue   |     1 |
     |  2 | dress   | white  |     1 |
     |  3 | t-shirt | blue   |     1 |
     |  4 | dress   | orange |     2 |
     |  5 | polo    | red    |     2 |
     |  6 | dress   | blue   |     2 |
     |  7 | t-shirt | white  |     2 |
     +----+---------+--------+-------+

     SELECT s.* FROM person p INNER JOIN shirt s
        ON s.owner = p.id
      WHERE p.name LIKE 'Lilliana%'
        AND s.color <> 'white';

     +----+-------+--------+-------+
     | id | style | color  | owner |
     +----+-------+--------+-------+
     |  4 | dress | orange |     2 |
     |  5 | polo  | red    |     2 |
     |  6 | dress | blue   |     2 |
     +----+-------+--------+-------+

When used in this fashion, the `REFERENCES' clause is not displayed in
the output of `SHOW CREATE TABLE' or `DESCRIBE':

     SHOW CREATE TABLE shirt\G
     *************************** 1. row ***************************
     Table: shirt
     Create Table: CREATE TABLE `shirt` (
     `id` smallint(5) unsigned NOT NULL auto_increment,
     `style` enum('t-shirt','polo','dress') NOT NULL,
     `color` enum('red','blue','orange','white','black') NOT NULL,
     `owner` smallint(5) unsigned NOT NULL,
     PRIMARY KEY  (`id`)
     ) ENGINE=MyISAM DEFAULT CHARSET=latin1

The use of `REFERENCES' in this way as a comment or `reminder' in a
column definition works with `MyISAM' tables.


File: manual.info,  Node: searching-on-two-keys,  Next: calculating-days,  Prev: example-foreign-keys,  Up: examples

3.6.7 Searching on Two Keys
---------------------------

An `OR' using a single key is well optimized, as is the handling of
`AND'.

The one tricky case is that of searching on two different keys combined
with `OR':

     SELECT field1_index, field2_index FROM test_table
     WHERE field1_index = '1' OR  field2_index = '1'

This case is optimized. See *Note index-merge-optimization::.

You can also solve the problem efficiently by using a `UNION' that
combines the output of two separate `SELECT' statements. See *Note
union::.

Each `SELECT' searches only one key and can be optimized:

     SELECT field1_index, field2_index
         FROM test_table WHERE field1_index = '1'
     UNION
     SELECT field1_index, field2_index
         FROM test_table WHERE field2_index = '1';


File: manual.info,  Node: calculating-days,  Next: example-auto-increment,  Prev: searching-on-two-keys,  Up: examples

3.6.8 Calculating Visits Per Day
--------------------------------

The following example shows how you can use the bit group functions to
calculate the number of days per month a user has visited a Web page.

     CREATE TABLE t1 (year YEAR(4), month INT(2) UNSIGNED ZEROFILL,
                  day INT(2) UNSIGNED ZEROFILL);
     INSERT INTO t1 VALUES(2000,1,1),(2000,1,20),(2000,1,30),(2000,2,2),
                 (2000,2,23),(2000,2,23);

The example table contains year-month-day values representing visits by
users to the page. To determine how many different days in each month
these visits occur, use this query:

     SELECT year,month,BIT_COUNT(BIT_OR(1<<day)) AS days FROM t1
            GROUP BY year,month;

Which returns:

     +------+-------+------+
     | year | month | days |
     +------+-------+------+
     | 2000 |    01 |    3 |
     | 2000 |    02 |    2 |
     +------+-------+------+

The query calculates how many different days appear in the table for
each year/month combination, with automatic removal of duplicate
entries.


File: manual.info,  Node: example-auto-increment,  Prev: calculating-days,  Up: examples

3.6.9 Using `AUTO_INCREMENT'
----------------------------

The `AUTO_INCREMENT' attribute can be used to generate a unique
identity for new rows:

     CREATE TABLE animals (
          id MEDIUMINT NOT NULL AUTO_INCREMENT,
          name CHAR(30) NOT NULL,
          PRIMARY KEY (id)
      );

     INSERT INTO animals (name) VALUES
         ('dog'),('cat'),('penguin'),
         ('lax'),('whale'),('ostrich');

     SELECT * FROM animals;

Which returns:

     +----+---------+
     | id | name    |
     +----+---------+
     |  1 | dog     |
     |  2 | cat     |
     |  3 | penguin |
     |  4 | lax     |
     |  5 | whale   |
     |  6 | ostrich |
     +----+---------+

You can retrieve the most recent `AUTO_INCREMENT' value with the
`LAST_INSERT_ID()' SQL function or the *Note `mysql_insert_id()':
mysql-insert-id. C API function. These functions are
connection-specific, so their return values are not affected by another
connection which is also performing inserts.

*Note*:

For a multiple-row insert, `LAST_INSERT_ID()' and *Note
`mysql_insert_id()': mysql-insert-id. actually return the
`AUTO_INCREMENT' key from the _first_ of the inserted rows. This allows
multiple-row inserts to be reproduced correctly on other servers in a
replication setup.

For `MyISAM' tables you can specify `AUTO_INCREMENT' on a secondary
column in a multiple-column index. In this case, the generated value
for the `AUTO_INCREMENT' column is calculated as
`MAX(AUTO_INCREMENT_COLUMN) + 1 WHERE prefix=GIVEN-PREFIX'. This is
useful when you want to put data into ordered groups.

     CREATE TABLE animals (
         grp ENUM('fish','mammal','bird') NOT NULL,
         id MEDIUMINT NOT NULL AUTO_INCREMENT,
         name CHAR(30) NOT NULL,
         PRIMARY KEY (grp,id)
     );

     INSERT INTO animals (grp,name) VALUES
         ('mammal','dog'),('mammal','cat'),
         ('bird','penguin'),('fish','lax'),('mammal','whale'),
         ('bird','ostrich');

     SELECT * FROM animals ORDER BY grp,id;

Which returns:

     +--------+----+---------+
     | grp    | id | name    |
     +--------+----+---------+
     | fish   |  1 | lax     |
     | mammal |  1 | dog     |
     | mammal |  2 | cat     |
     | mammal |  3 | whale   |
     | bird   |  1 | penguin |
     | bird   |  2 | ostrich |
     +--------+----+---------+

Note that in this case (when the `AUTO_INCREMENT' column is part of a
multiple-column index), `AUTO_INCREMENT' values are reused if you
delete the row with the biggest `AUTO_INCREMENT' value in any group.
This happens even for `MyISAM' tables, for which `AUTO_INCREMENT'
values normally are not reused.

If the `AUTO_INCREMENT' column is part of multiple indexes, MySQL will
generate sequence values using the index that begins with the
`AUTO_INCREMENT' column, if there is one. For example, if the `animals'
table contained indexes `PRIMARY KEY (grp, id)' and `INDEX (id)', MySQL
would ignore the `PRIMARY KEY' for generating sequence values. As a
result, the table would contain a single sequence, not a sequence per
`grp' value.

To start with an `AUTO_INCREMENT' value other than 1, you can set that
value with `CREATE TABLE' or `ALTER TABLE', like this:

     mysql> ALTER TABLE tbl AUTO_INCREMENT = 100;

More information about `AUTO_INCREMENT' is available here:

   * How to assign the `AUTO_INCREMENT' attribute to a column: *Note
     create-table::, and *Note alter-table::.

   * How `AUTO_INCREMENT' behaves depending on the SQL mode: *Note
     server-sql-mode::.

   * Find the row that contains the most recent AUTO_INCREMENT value:
     *Note comparison-operators::.

   * Set the `AUTO_INCREMENT' value to be used: *Note
     server-session-variables::.

   * `AUTO_INCREMENT' and replication: *Note replication-features::.

   * Server-system variables related to `AUTO_INCREMENT'
     (`auto_increment_increment' and `auto_increment_offset') that can
     be used for replication: *Note server-system-variables::.


File: manual.info,  Node: twin,  Next: apache,  Prev: examples,  Up: tutorial

3.7 Queries from the Twin Project
=================================

* Menu:

* twin-pool::                    Find All Non-distributed Twins
* twin-event::                   Show a Table of Twin Pair Status

At the places the early MySQL was developed (Analytikerna and Lentus),
the founders did systems and field work for a big research project.
This project was a collaboration between the Institute of Environmental
Medicine at Karolinska Institutet Stockholm and the Section on Clinical
Research in Aging and Psychology at the University of Southern
California.

The project involved lots of data collection from all twins in Sweden
older than 65 Years (see
`http://ki.se/ki/jsp/polopoly.jsp?d=9610&l=en').

Large parts of the project were administered with a Web interface
written using Perl and MySQL.


File: manual.info,  Node: twin-pool,  Next: twin-event,  Prev: twin,  Up: twin

3.7.1 Find All Non-distributed Twins
------------------------------------

The following query was used to determine what twins should be studied
further after a initial screening. The time for this was around MySQL
3.19 in 1997.

     SELECT
         CONCAT(p1.id, p1.tvab) + 0 AS tvid,
         CONCAT(p1.christian_name, ' ', p1.surname) AS Name,
         p1.postal_code AS Code,
         p1.city AS City,
         pg.abrev AS Area,
         IF(td.participation = 'Aborted', 'A', ' ') AS A,
         p1.dead AS dead1,
         l.event AS event1,
         td.suspect AS tsuspect1,
         id.suspect AS isuspect1,
         td.severe AS tsevere1,
         id.severe AS isevere1,
         p2.dead AS dead2,
         l2.event AS event2,
         h2.nurse AS nurse2,
         h2.doctor AS doctor2,
         td2.suspect AS tsuspect2,
         id2.suspect AS isuspect2,
         td2.severe AS tsevere2,
         id2.severe AS isevere2,
         l.finish_date
     FROM
         twin_project AS tp
         /* For Twin 1 */
         LEFT JOIN twin_data AS td ON tp.id = td.id
                   AND tp.tvab = td.tvab
         LEFT JOIN informant_data AS id ON tp.id = id.id
                   AND tp.tvab = id.tvab
         LEFT JOIN harmony AS h ON tp.id = h.id
                   AND tp.tvab = h.tvab
         LEFT JOIN lentus AS l ON tp.id = l.id
                   AND tp.tvab = l.tvab
         /* For Twin 2 */
         LEFT JOIN twin_data AS td2 ON p2.id = td2.id
                   AND p2.tvab = td2.tvab
         LEFT JOIN informant_data AS id2 ON p2.id = id2.id
                   AND p2.tvab = id2.tvab
         LEFT JOIN harmony AS h2 ON p2.id = h2.id
                   AND p2.tvab = h2.tvab
         LEFT JOIN lentus AS l2 ON p2.id = l2.id
                   AND p2.tvab = l2.tvab,
         person_data AS p1,
         person_data AS p2,
         postal_groups AS pg
     WHERE
         /* p1 gets main twin and p2 gets his/her twin. */
         /* ptvab is a field inverted from tvab */
         p1.id = tp.id AND p1.tvab = tp.tvab AND
         p2.id = p1.id AND p2.ptvab = p1.tvab AND
         /* Just the screening survey */
         tp.survey_no = 5 AND
         /* Skip if partner died before 65 but allow emigration (dead=9) */
         (p2.dead = 0 OR p2.dead = 9 OR
          (p2.dead = 1 AND
           (p2.death_date = 0 OR
            (((TO_DAYS(p2.death_date) - TO_DAYS(p2.birthday)) / 365)
             >= 65))))
         AND
         (
         /* Twin is suspect */
         (td.future_contact = 'Yes' AND td.suspect = 2) OR
         /* Twin is suspect - Informant is Blessed */
         (td.future_contact = 'Yes' AND td.suspect = 1
                                    AND id.suspect = 1) OR
         /* No twin - Informant is Blessed */
         (ISNULL(td.suspect) AND id.suspect = 1
                             AND id.future_contact = 'Yes') OR
         /* Twin broken off - Informant is Blessed */
         (td.participation = 'Aborted'
          AND id.suspect = 1 AND id.future_contact = 'Yes') OR
         /* Twin broken off - No inform - Have partner */
         (td.participation = 'Aborted' AND ISNULL(id.suspect)
                                       AND p2.dead = 0))
         AND
         l.event = 'Finished'
         /* Get at area code */
         AND SUBSTRING(p1.postal_code, 1, 2) = pg.code
         /* Not already distributed */
         AND (h.nurse IS NULL OR h.nurse=00 OR h.doctor=00)
         /* Has not refused or been aborted */
         AND NOT (h.status = 'Refused' OR h.status = 'Aborted'
         OR h.status = 'Died' OR h.status = 'Other')
     ORDER BY
         tvid;

Some explanations:

   * `CONCAT(p1.id, p1.tvab) + 0 AS tvid'

     We want to sort on the concatenated `id' and `tvab' in numerical
     order. Adding `0' to the result causes MySQL to treat the result
     as a number.

   * column `id'

     This identifies a pair of twins. It is an index in all tables.

   * column `tvab'

     This identifies a twin in a pair. It has a value of `1' or `2'.

   * column `ptvab'

     This is an inverse of `tvab'. When `tvab' is `1' this is `2', and
     vice versa. It exists to save typing and to make it easier for
     MySQL to optimize the query.

This query demonstrates, among other things, how to do lookups on a
table from the same table with a join (`p1' and `p2'). In the example,
this is used to check whether a twin's partner died before the age of
65. If so, the row is not returned.

All of the above exist in all tables with twin-related information. We
have an index on both `id, tvab' (all tables), and `id, ptvab'
(`person_data') to make queries faster.

When we did this work, our production machine was a 200MHz UltraSPARC,
and on that old hardware this query returned about 150-200 rows in less
than one second. The main table had 70k Rows.


File: manual.info,  Node: twin-event,  Prev: twin-pool,  Up: twin

3.7.2 Show a Table of Twin Pair Status
--------------------------------------

Each twin has a status code called `event'. The query shown here is
used to select all twin pairs combined by event. This indicates in how
many pairs both twins are finished, in how many pairs one twin is
finished and the other refused, and so on.

     SELECT
             t1.event,
             t2.event,
             COUNT(*)
     FROM
             lentus AS t1,
             lentus AS t2,
             twin_project AS tp
     WHERE
             /* We are looking at one pair at a time */
             t1.id = tp.id
             AND t1.tvab=tp.tvab
             AND t1.id = t2.id
             /* Just the screening survey */
             AND tp.survey_no = 5
             /* This makes each pair only appear once */
             AND t1.tvab='1' AND t2.tvab='2'
     GROUP BY
             t1.event, t2.event;


File: manual.info,  Node: apache,  Prev: twin,  Up: tutorial

3.8 Using MySQL with Apache
===========================

There are programs that let you authenticate your users from a MySQL
database and also let you write your log files into a MySQL table.

You can change the Apache logging format to be easily readable by MySQL
by putting the following into the Apache configuration file:

     LogFormat \
             "\"%h\",%{%Y%m%d%H%M%S}t,%>s,\"%b\",\"%{Content-Type}o\",  \
             \"%U\",\"%{Referer}i\",\"%{User-Agent}i\""

To load a log file in that format into MySQL, you can use a statement
something like this:

     LOAD DATA INFILE '/LOCAL/ACCESS_LOG' INTO TABLE TBL_NAME
     FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"' ESCAPED BY '\\'

The named table should be created to have columns that correspond to
those that the `LogFormat' line writes to the log file.


File: manual.info,  Node: programs,  Next: server-administration,  Prev: tutorial,  Up: Top

4 MySQL Programs
****************

* Menu:

* programs-overview::            Overview of MySQL Programs
* programs-using::               Using MySQL Programs
* programs-server::              MySQL Server and Server-Startup Programs
* programs-installation::        MySQL Installation-Related Programs
* programs-client::              MySQL Client Programs
* programs-admin-utils::         MySQL Administrative and Utility Programs
* programs-development::         MySQL Program Development Utilities
* programs-miscellaneous::       Miscellaneous Programs

This chapter provides a brief overview of the command-line programs
provided by MySQL AB. It also discusses the general syntax for
specifying options when you run these programs. Most programs have
options that are specific to their own operation, but the option syntax
is similar for all of them. Finally, the chapter provides more detailed
descriptions of individual programs, including which options they
recognize.


File: manual.info,  Node: programs-overview,  Next: programs-using,  Prev: programs,  Up: programs

4.1 Overview of MySQL Programs
==============================

There are many different programs in a MySQL installation. This section
provides a brief overview of them. Later sections provide a more
detailed description of each one, with the exception of MySQL Cluster
programs. Each program's description indicates its invocation syntax
and the options that it understands.  *Note mysql-cluster::, describes
programs specific to MySQL Cluster.

Most MySQL distributions include all of these programs, except for
those programs that are platform-specific. (For example, the server
startup scripts are not used on Windows.) The exception is that RPM
distributions are more specialized. There is one RPM for the server,
another for client programs, and so forth. If you appear to be missing
one or more programs, see *Note installing::, for information on types
of distributions and what they contain. It may be that you have a
distribution that does not include all programs and you need to install
an additional package.

Each MySQL program takes many different options. Most programs provide
a `--help' option that you can use to get a description of the
program's different options. For example, try `mysql --help'.

You can override default option values for MySQL programs by specifying
options on the command line or in an option file. See *Note
programs-using::, for general information on invoking programs and
specifying program options.

The MySQL server, `mysqld', is the main program that does most of the
work in a MySQL installation. The server is accompanied by several
related scripts that assist you in starting and stopping the server:

   * `mysqld'

     The SQL daemon (that is, the MySQL server). To use client
     programs, `mysqld' must be running, because clients gain access to
     databases by connecting to the server.  See *Note mysqld-server::.

   * `mysqld_safe'

     A server startup script. `mysqld_safe' attempts to start `mysqld'.
     See *Note mysqld-safe::.

   * `mysql.server'

     A server startup script. This script is used on systems that use
     System V-style run directories containing scripts that start
     system services for particular run levels. It invokes
     `mysqld_safe' to start the MySQL server. See *Note mysql-server::.

   * `mysqld_multi'

     A server startup script that can start or stop multiple servers
     installed on the system. See *Note mysqld-multi::. An alternative
     to `mysqld_multi' is `mysqlmanager', the MySQL Instance Manager.
     See *Note instance-manager::.

There are several programs that perform setup operations during MySQL
installation or upgrading:

   * `comp_err'

     This program is used during the MySQL build/installation process.
     It compiles error message files from the error source files. See
     *Note comp-err::.

   * `make_binary_distribution'

     This program makes a binary release of a compiled MySQL. This
     could be sent by FTP to `/pub/mysql/upload/' on `ftp.mysql.com'
     for the convenience of other MySQL users.

   * `make_win_bin_dist'

     This program is used on Windows. It packages a MySQL distribution
     for installation after the source distribution has been built. See
     *Note make-win-bin-dist::.

   * `mysql_fix_privilege_tables'

     This program is used after a MySQL upgrade operation. It updates
     the grant tables with any changes that have been made in newer
     versions of MySQL. See *Note mysql-fix-privilege-tables::.

     Note: As of MySQL 5.1.7, this program has been superseded by
     `mysql_upgrade'.

   * `mysql_install_db'

     This script creates the MySQL database and initializes the grant
     tables with default privileges. It is usually executed only once,
     when first installing MySQL on a system. See *Note
     unix-post-installation::, and *Note mysql-install-db::.

   * `mysql_secure_installation'

     This program enables you to improve the security of your MySQL
     installation. SQL. See *Note mysql-secure-installation::.

   * `mysql_tzinfo_to_sql'

     This program loads the time zone tables in the `mysql' database
     using the contents of the host system _zoneinfo_ database (the set
     of files describing time zones). SQL. See *Note
     mysql-tzinfo-to-sql::.

   * `mysql_upgrade'

     This program is used after a MySQL upgrade operation. It checks
     tables for incompatibilities and repairs them if necessary, and
     updates the grant tables with any changes that have been made in
     newer versions of MySQL. See *Note mysql-upgrade::.

MySQL client programs:

   * `mysql'

     The command-line tool for interactively entering SQL statements or
     executing them from a file in batch mode. See *Note mysql::.

   * `mysqladmin'

     A client that performs administrative operations, such as creating
     or dropping databases, reloading the grant tables, flushing tables
     to disk, and reopening log files.  `mysqladmin' can also be used
     to retrieve version, process, and status information from the
     server. See *Note mysqladmin::.

   * `mysqlcheck'

     A table-maintenance client that checks, repairs, analyzes, and
     optimizes tables. See *Note mysqlcheck::.

   * `mysqldump'

     A client that dumps a MySQL database into a file as SQL, text, or
     XML. See *Note mysqldump::.

   * `mysqlimport'

     A client that imports text files into their respective tables
     using `LOAD DATA INFILE'. See *Note mysqlimport::.

   * `mysqlshow'

     A client that displays information about databases, tables,
     columns, and indexes. See *Note mysqlshow::.

   * `mysqlslap'

     A client that is designed to emulate client load for a MySQL
     server and report the timing of each stage. It works as if
     multiple clients are accessing the server. See *Note mysqlslap::.

MySQL administrative and utility programs:

   * `innochecksum'

     An offline `InnoDB' offline file checksum utility. See *Note
     innochecksum::.

   * `myisam_ftdump'

     A utility that displays information about full-text indexes in
     `MyISAM' tables. See *Note myisam-ftdump::.

   * `myisamchk'

     A utility to describe, check, optimize, and repair `MyISAM'
     tables. See *Note myisamchk::.

   * `myisamlog', `isamlog'

     A utility that processes the contents of a `MyISAM' log file. See
     *Note myisamlog::.

   * `myisampack'

     A utility that compresses `MyISAM' tables to produce smaller
     read-only tables. See *Note myisampack::.

   * `mysqlaccess'

     A script that checks the access privileges for a hostname,
     username, and database combination. See *Note mysqlaccess::.

   * `mysqlbinlog'

     A utility for reading statements from a binary log. The log of
     executed statements contained in the binary log files can be used
     to help recover from a crash. See *Note mysqlbinlog::.

   * `mysqlhotcopy'

     A utility that quickly makes backups of `MyISAM' tables while the
     server is running.  See *Note mysqlhotcopy::.

   * `mysqlmanager'

     The MySQL Instance Manager, a program for monitoring and managing
     MySQL servers. See *Note instance-manager::.

     *Important*:

     MySQL Instance Manager has been deprecated and will be removed in
     MySQL 6.0.

   * `mysql_convert_table_format'

     A utility that converts tables in a database to use a given
     storage engine. See *Note mysql-convert-table-format::.

   * `mysql_find_rows'

     A utility that reads files containing SQL statements (such as
     update logs) and extracts statements that match a given regular
     expression. See *Note mysql-find-rows::.

   * `mysql_fix_extensions'

     A utility that converts the extensions for `MyISAM' table files to
     lowercase. This can be useful after transferring the files from a
     system with case-insensitive filenames to a system with
     case-sensitive filenames. See *Note mysql-fix-extensions::.

   * `mysql_setpermission'

     A utility for interactively setting permissions in the MySQL grant
     tables. See *Note mysql-setpermission::.

   * `mysql_waitpid'

     A utility that kills the process with a given process ID. See
     *Note mysql-waitpid::.

   * `mysql_zap'

     A utility that kills processes that match a pattern. See *Note
     mysql-zap::.

MySQL program-development utilities:

   * `msql2mysql'

     A shell script that converts `mSQL' programs to MySQL. It doesn't
     handle every case, but it gives a good start when converting.

   * `mysql_config'

     A shell script that produces the option values needed when
     compiling MySQL programs.

   * `my_print_defaults'

     A utility that shows which options are present in option groups of
     option files. See *Note my-print-defaults::.

   * `resolve_stack_dump'

     A utility program that resolves a numeric stack trace dump to
     symbols. See *Note resolve-stack-dump::.

Miscellaneous utilities:

   * `perror'

     A utility that displays the meaning of system or MySQL error
     codes. See *Note perror::.

   * `replace'

     A utility program that performs string replacement in the input
     text. See *Note replace-utility::.

   * `resolveip'

     A utility program that resolves a hostname to an IP address or
     vice versa. See *Note resolveip::.

MySQL AB also provides several GUI tools for administering and
otherwise working with MySQL Server:

   * MySQL Administrator: This tool is used for administering MySQL
     servers, databases, tables, and user accounts.

   * MySQL Query Browser: This graphical tool is provided by MySQL AB
     for creating, executing, and optimizing queries on MySQL databases.

   * MySQL Migration Toolkit: This tool helps you migrate schemas and
     data from other relational database management systems for use
     with MySQL.

These GUI programs are available at `http://dev.mysql.com/downloads/'.
Each has its own manual that you can access at
`http://dev.mysql.com/doc/'.

MySQL client programs that communicate with the server using the MySQL
client/server library use the following environment variables:

`MYSQL_UNIX_PORT'  The default Unix socket file; used for connections to
                   `localhost'
`MYSQL_TCP_PORT'   The default port number; used for TCP/IP connections
`MYSQL_PWD'        The default password
`MYSQL_DEBUG'      Debug trace options when debugging
`TMPDIR'           The directory where temporary tables and files are
                   created

For a full list of environment variables used by MySQL programs, see
*Note environment-variables::.

Use of `MYSQL_PWD' is insecure. See *Note password-security::.


File: manual.info,  Node: programs-using,  Next: programs-server,  Prev: programs-overview,  Up: programs

4.2 Using MySQL Programs
========================

* Menu:

* invoking-programs::            Invoking MySQL Programs
* connecting::                   Connecting to the MySQL Server
* program-options::              Specifying Program Options
* setting-environment-variables::  Setting Environment Variables


File: manual.info,  Node: invoking-programs,  Next: connecting,  Prev: programs-using,  Up: programs-using

4.2.1 Invoking MySQL Programs
-----------------------------

To invoke a MySQL program from the command line (that is, from your
shell or command prompt), enter the program name followed by any
options or other arguments needed to instruct the program what you want
it to do. The following commands show some sample program invocations.
``shell>'' represents the prompt for your command interpreter; it is
not part of what you type. The particular prompt you see depends on your
command interpreter. Typical prompts are `$' for `sh' or `bash', `%'
for `csh' or `tcsh', and `C:\>' for the Windows `command.com' or
`cmd.exe' command interpreters.

     shell> mysql --user=root test
     shell> mysqladmin extended-status variables
     shell> mysqlshow --help
     shell> mysqldump -u root personnel

Arguments that begin with a single or double dash (``-'', ``--'')
specify program options.  Options typically indicate the type of
connection a program should make to the server or affect its
operational mode. Option syntax is described in *Note program-options::.

Non-option arguments (arguments with no leading dash) provide
additional information to the program. For example, the `mysql' program
interprets the first non-option argument as a database name, so the
command `mysql --user=root test' indicates that you want to use the
`test' database.

Later sections that describe individual programs indicate which options
a program understands and describe the meaning of any additional
non-option arguments.

Some options are common to a number of programs. The most frequently
used of these are the `--host' (or `-h'), `--user' (or `-u'), and
`--password' (or `-p') options that specify connection parameters.
They indicate the host where the MySQL server is running, and the
username and password of your MySQL account. All MySQL client programs
understand these options; they allow you to specify which server to
connect to and the account to use on that server. Other connection
options are `--port' (or `-P') to specify a TCP/IP port number and
`--socket' (or `-S') to specify a Unix socket file on Unix (or named
pipe name on Windows). For more information on options that specify
connection options, see *Note connecting::.

You may find it necessary to invoke MySQL programs using the pathname
to the `bin' directory in which they are installed. This is likely to
be the case if you get a `program not found' error whenever you attempt
to run a MySQL program from any directory other than the `bin'
directory. To make it more convenient to use MySQL, you can add the
pathname of the `bin' directory to your `PATH' environment variable
setting. That enables you to run a program by typing only its name, not
its entire pathname. For example, if `mysql' is installed in
`/usr/local/mysql/bin', you can run the program by invoking it as
`mysql', and it is not necessary to invoke it as
`/usr/local/mysql/bin/mysql'.

Consult the documentation for your command interpreter for instructions
on setting your `PATH' variable. The syntax for setting environment
variables is interpreter-specific.  (Some information is given in *Note
setting-environment-variables::.) After modifying your `PATH' setting,
open a new console window on Windows or log in again on Unix so that
the setting goes into effect.


File: manual.info,  Node: connecting,  Next: program-options,  Prev: invoking-programs,  Up: programs-using

4.2.2 Connecting to the MySQL Server
------------------------------------

For a client program to be able to connect to the MySQL server, it must
use the proper connection parameters, such as the name of the host
where the server is running and the username and password of your MySQL
account. Each connection parameter has a default value, but you can
override them as necessary using program options specified either on
the command line or in an option file.

The examples here use the `mysql' client program, but the principles
apply to other clients such as `mysqldump', `mysqladmin', or
`mysqlshow'.

This command invokes `mysql' without specifying any connection
parameters explicitly:

     shell> mysql

Because there are no parameter options, the default values apply:

   * The default hostname is `localhost'. On Unix, this has a special
     meaning, as described later.

   * The default username is `ODBC' on Windows or your Unix login name
     on Unix.

   * No password is sent if neither `-p' nor `--password' is given.

To specify the hostname and username explicitly, as well as a password,
supply appropriate options on the command line:

     shell> mysql --host=localhost --user=myname --password=mypass
     shell> mysql -h localhost -u myname -pmypass

For password options, the password value is optional:

   * If you use a `-p' or `--password' option but do not specify the
     password value, the client program prompts you to enter the
     password. The password is not displayed as you enter it. This is
     more secure than giving the password on the command line.  Any
     user on your system may be able to see a password specified on the
     command line by executing a command such as `ps auxw'. See *Note
     password-security::.

   * If you use a `-p' or `--password' option and do specify the
     password value, there must be _no space_ between `-p' or
     `--password=' and the password following it.

On Unix, MySQL programs treat the hostname `localhost' specially, in a
way that is likely different from what you expect compared to other
network-based programs. For connections to `localhost', MySQL programs
attempt to connect to the local server by using a Unix socket file.
This occurs even if a `--port' or `-P' option is given to specify a
port number. To ensure that the client makes a TCP/IP connection to the
local server, use `--host' or `-h' to specify a hostname value of
`127.0.0.1', or the IP address or name of the local server. You can
also specify the connection protocol explicitly, even for `localhost',
by using the `--protocol=TCP' option. For example:

     shell> mysql --host=127.0.0.1
     shell> mysql --protocol=TCP

The `--protocol' option enables you to establish a particular type of
connection even when the other options would normally default to some
other protocol.

On Windows, you can force a MySQL client to use a named-pipe connection
by specifying the `--pipe' or `--protocol=PIPE' option, or by specifying
`.' (period) as the host name. If named-pipe connections are not
enabled, an error occurs. Use the `--socket' option to specify the name
of the pipe if you do not want to use the default pipe name.

Connections to remote servers always use TCP/IP. This command connects
to the server running on `remote.example.com' using the default port
number (3306):

     shell> mysql --host=remote.example.com

To specify a port number explicitly, use the `--port' or `-P' option:

     shell> mysql --host=remote.example.com --port=13306

You can specify a port number for connections to a local server, too.
However, as indicated previously, connections to `localhost' on Unix
will use a socket file by default. You will need to force a TCP/IP
connection as already described or any option that specifies a port
number will be ignored.

For this command, the program uses a socket file on Unix and the
`--port' option is ignored:

     shell> mysql --port=13306 --host=localhost

To cause the port number to be used, invoke the program in either of
these ways:

     shell> mysql --port=13306 --host=127.0.0.1
     shell> mysql --port=13306 --protocol=TCP

The following options may be used to control how client programs
connect to the server:

   * `--host=HOST_NAME', `-h HOST_NAME'

     The host where the server is running. The default value is
     `localhost'.

   * `--password[=PASS_VAL]', `-p[PASS_VAL]'

     The password of the MySQL account. As described earlier, the
     password value is optional, but if given, there must be _no space_
     between `-p' or `--password=' and the password following it.  The
     default is to send no password.

   * `--pipe', `-W'

     On Windows, connect to the server via a named pipe. This option
     applies for connections to a local server only. The server must
     have been started with the `--enable-named-pipe' option to enable
     named-pipe connections.

   * `--port=PORT_NUM', `-P PORT_NUM'

     The port number to use for the connection, for connections made
     via TCP/IP. The default port number is 3306.

   * `--protocol={TCP|SOCKET|PIPE|MEMORY}'

     This option explicitly specifies a protocol to use for connecting
     to the server. It is useful when the other connection parameters
     normally would cause a protocol to be used other than the one you
     want. For example, connections on Unix to `localhost' are made via
     a Unix socket file by default:

          shell> mysql --host=localhost

     To force a TCP/IP connection to be used instead, specify a
     `--protocol' option:

          shell> mysql --host=localhost --protocol=TCP

     The following table shows the allowable `--protocol' option values
     and indicates the platforms on which each value may be used. The
     values are not case sensitive.

     _`--protocol' _Connection Protocol_              _Allowable
     Value_                                           Operating Systems_
     `TCP'         TCP/IP connection to local or      All
                   remote server                      
     `SOCKET'      Unix socket file connection to     Unix only
                   local server                       
     `PIPE'        Named-pipe connection to local     Windows only
                   server                             
     `MEMORY'      Shared-memory connection to local  Windows only
                   server                             

   * `--shared-memory-base-name=NAME'

     On Windows, the shared-memory name to use, for connections made
     via shared memory to a local server. The default value is `MYSQL'.
     The shared-memory name is case sensitive.

     The server must be started with the `--shared-memory' option to
     enable shared-memory connections.

   * `--socket=FILE_NAME', `-S FILE_NAME'

     On Unix, the name of the Unix socket file to use, for connections
     made via a named pipe to a local server. The default Unix socket
     filename is `/tmp/mysql.sock'.

     On Windows, the name of the named pipe to use, for connections to
     a local server. The default Windows pipe name is `MySQL'. The pipe
     name is not case sensitive.

     The server must be started with the `--enable-named-pipe' option
     to enable named-pipe connections.

   * `--ssl*'

     Options that begin with `--ssl' are used for establishing a secure
     connection to the server via SSL, if the server is configured with
     SSL support. For details, see *Note ssl-options::.

   * `--user=USER_NAME', `-u USER_NAME'

     The username of the MySQL account you want to use. The default
     username is `ODBC' on Windows or your Unix login name on Unix.

It is possible to specify different default values to be used when you
make a connection so that you need not enter them on the command line
each time you invoke a client program. This can be done in a couple of
ways:

   * You can specify connection parameters in the `[client]' section of
     an option file. The relevant section of the file might look like
     this:

          [client]
          host=HOST_NAME
          user=USER_NAME
          password=YOUR_PASS

     *Note option-files::, discusses option files further.

   * You can specify some connection parameters using environment
     variables. The host can be specified for `mysql' using
     `MYSQL_HOST'.  The MySQL username can be specified using `USER'
     (this is for Windows and NetWare only). The password can be
     specified using `MYSQL_PWD', although this is insecure; see *Note
     password-security::. For a list of variables, see *Note
     environment-variables::.


File: manual.info,  Node: program-options,  Next: setting-environment-variables,  Prev: connecting,  Up: programs-using

4.2.3 Specifying Program Options
--------------------------------

* Menu:

* command-line-options::         Using Options on the Command Line
* option-files::                 Using Option Files
* program-variables::            Using Options to Set Program Variables
* option-defaults-equals::       Option Defaults, Options Expecting Values, and the `=' Sign

There are several ways to specify options for MySQL programs:

   * List the options on the command line following the program name.
     This is most common for options that apply to a specific
     invocation of the program.

   * List the options in an option file that the program reads when it
     starts. This is common for options that you want the program to
     use each time it runs.

   * List the options in environment variables (see *Note
     setting-environment-variables::). This method is useful for
     options that you want to apply each time the program runs. In
     practice, option files are used more commonly for this purpose,
     but *Note multiple-unix-servers::, discusses one situation in
     which environment variables can be very helpful. It describes a
     handy technique that uses such variables to specify the TCP/IP
     port number and Unix socket file for the server and for client
     programs.

MySQL programs determine which options are given first by examining
environment variables, then by reading option files, and then by
checking the command line. This means that environment variables have
the lowest precedence and command-line options the highest.

Because options are processed in order, if an option is specified
multiple times, the last occurrence takes precedence. The following
command causes `mysql' to connect to the server running on `localhost':

     shell> mysql -h example.com -h localhost

If conflicting or related options are given, later options take
precedence over earlier options. The following command runs `mysql' in
`no column names' mode:

     shell> mysql --column-names --skip-column-names

An option can be specified by writing it in full or as any unambiguous
prefix. For example, the `--compress' option can be given to
`mysqldump' as `--compr', but not as `--comp' because the latter is
ambiguous:

     shell> mysqldump --comp
     mysqldump: ambiguous option '--comp' (compatible, compress)

Be aware that the use of option prefixes can cause problems in the
event that new options are implemented for a program. A prefix that is
unambigious now might become ambiguous in the future.

You can take advantage of the way that MySQL programs process options
by specifying default values for a program's options in an option file.
That enables you to avoid typing them each time you run the program,
but also allows you to override the defaults if necessary by using
command-line options.


File: manual.info,  Node: command-line-options,  Next: option-files,  Prev: program-options,  Up: program-options

4.2.3.1 Using Options on the Command Line
.........................................

* Menu:

* option-modifiers::             Program Option Modifiers

Program options specified on the command line follow these rules:

   * Options are given after the command name.

   * An option argument begins with one dash or two dashes, depending
     on whether it is a short form or long form of the option name.
     Many options have both short and long forms.  For example, `-?'
     and `--help' are the short and long forms of the option that
     instructs a MySQL program to display its help message.

   * Option names are case sensitive. `-v' and `-V' are both legal and
     have different meanings. (They are the corresponding short forms
     of the `--verbose' and `--version' options.)

   * Some options take a value following the option name. For example,
     `-h localhost' or `--host=localhost' indicate the MySQL server
     host to a client program. The option value tells the program the
     name of the host where the MySQL server is running.

   * For a long option that takes a value, separate the option name and
     the value by an ``='' sign. For a short option that takes a value,
     the option value can immediately follow the option letter, or
     there can be a space between: `-hlocalhost' and `-h localhost' are
     equivalent. An exception to this rule is the option for specifying
     your MySQL password. This option can be given in long form as
     `--password=PASS_VAL' or as `--password'. In the latter case (with
     no password value given), the program prompts you for the
     password. The password option also may be given in short form as
     `-pPASS_VAL' or as `-p'. However, for the short form, if the
     password value is given, it must follow the option letter with _no
     intervening space_. The reason for this is that if a space follows
     the option letter, the program has no way to tell whether a
     following argument is supposed to be the password value or some
     other kind of argument. Consequently, the following two commands
     have two completely different meanings:

          shell> mysql -ptest
          shell> mysql -p test

     The first command instructs `mysql' to use a password value of
     `test', but specifies no default database. The second instructs
     `mysql' to prompt for the password value and to use `test' as the
     default database.

   * Within option names, dash (``-'') and underscore (``_'') may be
     used interchangeably. For example, `--skip-grant-tables' and
     `--skip_grant_tables' are equivalent.  (However, the leading
     dashes cannot be given as underscores.)

Another option that may occasionally be useful with `mysql' is the
`--execute' or `-e' option, which can be used to pass SQL statements to
the server. When this option is used, `mysql' executes the statements
and exits. The statements must be enclosed by quotation marks. For
example, you can use the following command to obtain a list of user
accounts:

     shell> mysql -u root -p --execute="SELECT User, Host FROM user" mysql
     Enter password: ******
     +------+-----------+
     | User | Host      |
     +------+-----------+
     |      | gigan     |
     | root | gigan     |
     |      | localhost |
     | jon  | localhost |
     | root | localhost |
     +------+-----------+
     shell>

Note that the long form (`--execute') is followed by an equals sign
(`=').

If you wish to use quoted values within a statement, you will either
need to escape the inner quotes, or use a different type of quotes
within the statement from those used to quote the statement itself. The
capabilities of your command processor dictate your choices for whether
you can use single or double quotation marks and the syntax for
escaping quote characters.  For example, if your command processor
supports quoting with single or double quotes, you can double quotes
around the statement, and single quotes for any quoted values within the
statement.

In the preceding example, the name of the `mysql' database was passed
as a separate argument. However, the same statement could have been
executed using this command, which specifies no default database:

     mysql> mysql -u root -p --execute="SELECT User, Host FROM mysql.user"

Multiple SQL statements may be passed on the command line, separated by
semicolons:

     shell> mysql -u root -p -e "SELECT VERSION();SELECT NOW()"
     Enter password: ******
     +-----------------+
     | VERSION()       |
     +-----------------+
     | 5.1.5-alpha-log |
     +-----------------+
     +---------------------+
     | NOW()               |
     +---------------------+
     | 2006-01-05 21:19:04 |
     +---------------------+

The `--execute' or `-e' option may also be used to pass commands in an
analogous fashion to the `ndb_mgm' management client for MySQL Cluster.
See *Note mysql-cluster-multi-shutdown-restart::, for an example.


File: manual.info,  Node: option-modifiers,  Prev: command-line-options,  Up: command-line-options

4.2.3.2 Program Option Modifiers
................................

Some options control behavior that can be turned on or off.  For
example, the `mysql' client supports a `--column-names' option that
determines whether or not to display a row of column names at the
beginning of query results. By default, this option is enabled. However,
you may want to disable it in some instances, such as when sending the
output of `mysql' into another program that expects to see only data
and not an initial header line.

To disable column names, you can specify the option using any of these
forms:

     --disable-column-names
     --skip-column-names
     --column-names=0

The `--disable' and `--skip' prefixes and the `=0' suffix all have the
same effect: They turn the option off.

The `enabled' form of the option may be specified in any of these ways:

     --column-names
     --enable-column-names
     --column-names=1

If an option is prefixed by `--loose', a program does not exit with an
error if it does not recognize the option, but instead issues only a
warning:

     shell> mysql --loose-no-such-option
     mysql: WARNING: unknown option '--no-such-option'

The `--loose' prefix can be useful when you run programs from multiple
installations of MySQL on the same machine and list options in an
option file, An option that may not be recognized by all versions of a
program can be given using the `--loose' prefix (or `loose' in an
option file). Versions of the program that recognize the option process
it normally, and versions that do not recognize it issue a warning and
ignore it.

`mysqld' enables a limit to be placed on how large client programs can
set dynamic system variables. To do this, use a `--maximum' prefix with
the variable name. For example, `--maximum-query_cache_size=4M'
prevents any client from making the query cache size larger than 4MB.


File: manual.info,  Node: option-files,  Next: program-variables,  Prev: command-line-options,  Up: program-options

4.2.3.3 Using Option Files
..........................

* Menu:

* option-file-options::          Command-Line Options that Affect Option-File Handling
* option-files-preconfigured::   Preconfigured Option Files

Most MySQL programs can read startup options from option files (also
sometimes called configuration files). Option files provide a
convenient way to specify commonly used options so that they need not
be entered on the command line each time you run a program. For the
MySQL server, MySQL provides a number of *Note preconfigured option
files: option-files-preconfigured.

To determine whether a program reads option files, invoke it with the
`--help' option. (For `mysqld', use `--verbose' and `--help'.) If the
program reads option files, the help message indicates which files it
looks for and which option groups it recognizes.

*Note*:

Option files used with MySQL Cluster programs are covered in *Note
mysql-cluster-configuration::.

On Windows, MySQL programs read startup options from the following
files:

*Filename*             *Purpose*
`WINDIR\my.ini',       Global options
`WINDIR\my.cnf'        
`C:\my.ini',           Global options
`C:\my.cnf'            
`INSTALLDIR\my.ini',   Global options
`INSTALLDIR\my.cnf'    
`defaults-extra-file'  The file specified with
                       `--defaults-extra-file=PATH', if any

WINDIR represents the location of your Windows directory. This is
commonly `C:\WINDOWS'. You can determine its exact location from the
value of the `WINDIR' environment variable using the following command:

     C:\> echo %WINDIR%

INSTALLDIR represents the MySQL installation directory. This is
typically `C:\PROGRAMDIR\MySQL\MySQL 5.1 Server' where PROGRAMDIR
represents the programs directory (usually `Program Files' on
English-language versions of Windows), when MySQL 5.1 has been
installed using the installation and configuration wizards. See *Note
mysql-config-wizard-file-location::.

On Unix, MySQL programs read startup options from the following files:

*Filename*             *Purpose*
`/etc/my.cnf'          Global options
`/etc/mysql/my.cnf'    Global options (as of MySQL 5.1.15)
`SYSCONFDIR/my.cnf'    Global options
`$MYSQL_HOME/my.cnf'   Server-specific options
`defaults-extra-file'  The file specified with
                       `--defaults-extra-file=PATH', if any
`~/.my.cnf'            User-specific options

SYSCONFDIR represents the directory specified with the `--sysconfdir'
option to `configure' when MySQL was built. By default, this is the
`etc' directory located under the compiled-in installation directory.
This location is used as of MySQL 5.1.10. (From 5.1.10 to 5.1.22, it
was read last, after `~/.my.cnf'.)

`MYSQL_HOME' is an environment variable containing the path to the
directory in which the server-specific `my.cnf' file resides.

If `MYSQL_HOME' is not set and you start the server using the
`mysqld_safe' program, `mysqld_safe' attempts to set `MYSQL_HOME' as
follows:

   * Let BASEDIR and DATADIR represent the pathnames of the MySQL base
     directory and data directory, respectively.

   * If there is a `my.cnf' file in DATADIR but not in BASEDIR,
     `mysqld_safe' sets `MYSQL_HOME' to DATADIR.

   * Otherwise, if `MYSQL_HOME' is not set and there is no `my.cnf'
     file in DATADIR, `mysqld_safe' sets `MYSQL_HOME' to BASEDIR.

In MySQL 5.1, use of DATADIR as the location for `my.cnf' is deprecated.

Typically, DATADIR is `/usr/local/mysql/data' for a binary installation
or `/usr/local/var' for a source installation. Note that this is the
data directory location that was specified at configuration time, not
the one specified with the `--datadir' option when `mysqld' starts. Use
of `--datadir' at runtime has no effect on where the server looks for
option files, because it looks for them before processing any options.

MySQL looks for option files in the order just described and reads any
that exist. If an option file that you want to use does not exist,
create it with a plain text editor.

If multiple instances of a given option are found, the last instance
takes precedence. There is one exception: For `mysqld', the _first_
instance of the `--user' option is used as a security precaution, to
prevent a user specified in an option file from being overridden on the
command line.

*Note*:

On Unix platforms, MySQL ignores configuration files that are
world-writable. This is intentional as a security measure.

Any long option that may be given on the command line when running a
MySQL program can be given in an option file as well.  To get the list
of available options for a program, run it with the `--help' option.

The syntax for specifying options in an option file is similar to
command-line syntax, except that you omit the leading two dashes and
you specify only one option per line. For example, `--quick' and
`--host=localhost' on the command line should be specified as `quick'
and `host=localhost' on separate lines in an option file. To specify an
option of the form `--loose-OPT_NAME' in an option file, write it as
`loose-OPT_NAME'.

Empty lines in option files are ignored. Non-empty lines can take any
of the following forms:

   * `#COMMENT', `;COMMENT'

     Comment lines start with ``#'' or ``;''. A ``#'' comment can start
     in the middle of a line as well.

   * `[GROUP]'

     GROUP is the name of the program or group for which you want to
     set options. After a group line, any option-setting lines apply to
     the named group until the end of the option file or another group
     line is given.

   * `OPT_NAME'

     This is equivalent to `--OPT_NAME' on the command line.

   * `OPT_NAME=VALUE'

     This is equivalent to `--OPT_NAME=VALUE' on the command line. In
     an option file, you can have spaces around the ``='' character,
     something that is not true on the command line. You can enclose
     the value within single quotes or double quotes, which is useful
     if the value contains a ``#'' comment character or whitespace.

For options that take a numeric value, the value can be given with a
suffix of `K', `M', or `G' (either uppercase or lowercase) to indicate
a multiplier of 1024, 1024^2 or 1024^3. For example, the following
command tells `mysqladmin' to ping the server 1024 times, sleeping 10
seconds between each ping:

     mysql> mysqladmin --count=1K --sleep=10 ping

Leading and trailing blanks are automatically deleted from option names
and values. You may use the escape sequences ``\b'', ``\t'', ``\n'',
``\r'', ``\\'', and ``\s'' in option values to represent the backspace,
tab, newline, carriage return, backslash, and space characters.

Because the ``\\'' escape sequence represents a single backslash, you
must write each ``\'' as ``\\''. Alternatively, you can specify the
value using ``/'' rather than ``\'' as the pathname separator.

If an option group name is the same as a program name, options in the
group apply specifically to that program. For example, the `[mysqld]'
and `[mysql]' groups apply to the `mysqld' server and the `mysql'
client program, respectively.

The `[client]' option group is read by all client programs (but _not_ by
`mysqld'). This allows you to specify options that apply to all
clients. For example, `[client]' is the perfect group to use to specify
the password that you use to connect to the server. (But make sure that
the option file is readable and writable only by yourself, so that
other people cannot find out your password.)  Be sure not to put an
option in the `[client]' group unless it is recognized by _all_ client
programs that you use. Programs that do not understand the option quit
after displaying an error message if you try to run them.

Here is a typical global option file:

     [client]
     port=3306
     socket=/tmp/mysql.sock

     [mysqld]
     port=3306
     socket=/tmp/mysql.sock
     key_buffer_size=16M
     max_allowed_packet=8M

     [mysqldump]
     quick

The preceding option file uses `VAR_NAME=VALUE' syntax for the lines
that set the `key_buffer_size' and `max_allowed_packet' variables.

Here is a typical user option file:

     [client]
     # The following password will be sent to all standard MySQL clients
     password="my_password"

     [mysql]
     no-auto-rehash
     connect_timeout=2

     [mysqlhotcopy]
     interactive-timeout

If you want to create option groups that should be read by `mysqld'
servers from a specific MySQL release series only, you can do this by
using groups with names of `[mysqld-5.0]', `[mysqld-5.1]', and so
forth. The following group indicates that the `--new' option should be
used only by MySQL servers with 5.1.x version numbers:

     [mysqld-5.1]
     new

It is possible to use `!include' directives in option files to include
other option files and `!includedir' to search specific directories for
option files. For example, to include the `/home/mydir/myopt.cnf' file,
use the following directive:

     !include /home/mydir/myopt.cnf

To search the `/home/mydir' directory and read option files found
there, use this directive:

     !includedir /home/mydir

There is no guarantee about the order in which the option files in the
directory will be read.

*Note*:

Currently, any files to be found and included using the `!includedir'
directive on Unix operating systems _must_ have filenames ending in
`.cnf'. On Windows, this directive checks for files with the `.ini' or
`.cnf' extension.

Write the contents of an included option file like any other option
file. That is, it should contain groups of options, each preceded by a
`[GROUP]' line that indicates the program to which the options apply.

While an included file is being processed, only those options in groups
that the current program is looking for are used. Other groups are
ignored. Suppose that a `my.cnf' file contains this line:

     !include /home/mydir/myopt.cnf

And suppose that `/home/mydir/myopt.cnf' looks like this:

     [mysqladmin]
     force

     [mysqld]
     key_buffer_size=16M

If `my.cnf' is processed by `mysqld', only the `[mysqld]' group in
`/home/mydir/myopt.cnf' is used. If the file is processed by
`mysqladmin', only the `[mysqldamin]' group is used. If the file is
processed by any other program, no options in `/home/mydir/myopt.cnf'
are used.

The `!includedir' directive is processed similarly except that all
option files in the named directory are read.


File: manual.info,  Node: option-file-options,  Next: option-files-preconfigured,  Prev: option-files,  Up: option-files

4.2.3.4 Command-Line Options that Affect Option-File Handling
.............................................................

Most MySQL programs that support option files handle the following
options. They affect option-file handling, so they must be given on the
command line and not in an option file.  To work properly, each of
these options must immediately follow the command name, with the
exception that `--print-defaults' may be used immediately after
`--defaults-file' or `--defaults-extra-file'. Also, when specifying
filenames, you should avoid the use of the ``~'' shell metacharacter
because it might not be interpreted as you expect.

   *  `--no-defaults'

     Don't read any option files.

   *  `--print-defaults'

     Print the program name and all options that it gets from option
     files.

   *  `--defaults-file=FILE_NAME'

     Use only the given option file.  FILE_NAME is the full pathname to
     the file. If the file does not exist or is otherwise inaccessible,
     the program will exit with an error.

   *  `--defaults-extra-file=FILE_NAME'

     Read this option file after the global option file but (on Unix)
     before the user option file.  FILE_NAME is the full pathname to
     the file. If the file does not exist or is otherwise inaccessible,
     the program will exit with an error.

   *  `--defaults-group-suffix=STR'

     If this option is given, the program reads not only its usual
     option groups, but also groups with the usual names and a suffix
     of STR. For example, the `mysql' client normally reads the
     `[client]' and `[mysql]' groups. If the
     `--default-group-suffix=_other' option is given, `mysql' also
     reads the `[client_other]' and `[mysql_other]' groups.


File: manual.info,  Node: option-files-preconfigured,  Prev: option-file-options,  Up: option-files

4.2.3.5 Preconfigured Option Files
..................................

MySQL provides a number of preconfigured option files that can be used
as a basis for tuning the MySQL server. Look for files such as
`my-small.cnf', `my-medium.cnf', `my-large.cnf', and `my-huge.cnf',
which are sample option files for small, medium, large, and very large
systems. On Windows, the extension is `.ini' rather than `.cnf'
extension.

*Note*:

On Windows, the `.cnf' or `.ini' option file extension might not be
displayed.

For a binary distribution, look for the files in or under your
installation directory. If you have a source distribution, look in the
`support-files' directory. You can rename a copy of a sample file and
place it in the appropriate location for use as a base configuration
file.  Regarding names and appropriate location, see the general
information provided in *Note option-files::.


File: manual.info,  Node: program-variables,  Next: option-defaults-equals,  Prev: option-files,  Up: program-options

4.2.3.6 Using Options to Set Program Variables
..............................................

Many MySQL programs have internal variables that can be set at runtime
using the `SET' statement. See *Note set-option::, and *Note
using-system-variables::.

Most of these program variables also can be set at server startup by
using the same syntax that applies to specifying program options. For
example, `mysql' has a `max_allowed_packet' variable that controls the
maximum size of its communication buffer. To set the
`max_allowed_packet' variable for `mysql' to a value of 16MB, use
either of the following commands:

     shell> mysql --max_allowed_packet=16777216
     shell> mysql --max_allowed_packet=16M

The first command specifies the value in bytes. The second specifies
the value in megabytes. For variables that take a numeric value, the
value can be given with a suffix of `K', `M', or `G' (either uppercase
or lowercase) to indicate a multiplier of 1024, 1024^2 or 1024^3. (For
example, when used to set `max_allowed_packet', the suffixes indicate
units of kilobytes, megabytes, or gigabytes.)

In an option file, variable settings are given without the leading
dashes:

     [mysql]
     max_allowed_packet=16777216

Or:

     [mysql]
     max_allowed_packet=16M

If you like, underscores in a variable name can be specified as dashes.
The following option groups are equivalent. Both set the size of the
server's key buffer to 512MB:

     [mysqld]
     key_buffer_size=512M

     [mysqld]
     key-buffer-size=512M

A variable can be specified by writing it in full or as any unambiguous
prefix. For example, the `max_buffer_length' variable can be set for
`mysql' as `--max_a', but not as `--max' because the latter is
ambiguous:

     shell> mysql --max=1000000
     mysql: ambiguous option '--max=1000000' (max_allowed_packet, max_join_size)

Be aware that the use of variable prefixes can cause problems in the
event that new variables are implemented for a program. A prefix that
is unambigious now might become ambiguous in the future.

Suffixes for specifying a value multiplier can be used when setting a
variable at server startup, but not to set the value with `SET' at
runtime. On the other hand, with `SET' you can assign a variable's
value using an expression, which is not true when you set a variable at
server startup. For example, the first of the following lines is legal
at server startup, but the second is not:

     shell> mysql --max_allowed_packet=16M
     shell> mysql --max_allowed_packet=16*1024*1024

Conversely, the second of the following lines is legal at runtime, but
the first is not:

     mysql> SET GLOBAL max_allowed_packet=16M;
     mysql> SET GLOBAL max_allowed_packet=16*1024*1024;

*Note*:

Before MySQL 4.0.2, the only syntax for setting program variables was
`--set-variable=OPTION=VALUE' (or `set-variable=OPTION=VALUE' in option
files). Underscores cannot be given as dashes, and the variable name
must be specified in full. This syntax still is recognized, but is now
deprecated.


File: manual.info,  Node: option-defaults-equals,  Prev: program-variables,  Up: program-options

4.2.3.7 Option Defaults, Options Expecting Values, and the `=' Sign
...................................................................

By convention, long forms of options that assign a value are written
with an equals (`=') sign, like this:

     shell> mysql --host=tonfisk --user=jon

For options that require a value (that is, not having a default value),
the equals sign is not required, and so the following is also valid:

     shell> mysql --host tonfisk --user jon

In both cases, the `mysql' client attempts to connect to a MySQL server
running on the host named `tonfisk' using an account with the username
`jon'.

Due to this behavior, problems can occasionally arise when no value is
provided for an option that expects one. Consider the following
example, where a user connects to a MySQL server running on host
`tonfisk' as user `jon':

     shell> mysql --host 85.224.35.45 --user jon
     Welcome to the MySQL monitor.  Commands end with ; or \g.
     Your MySQL connection id is 3
     Server version: 5.1.28 Source distribution

     Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

     mysql> SELECT CURRENT_USER();
     +----------------+
     | CURRENT_USER() |
     +----------------+
     | jon@%          |
     +----------------+
     1 row in set (0.00 sec)

Omitting the required value for one of these option yields an error,
such as the one shown here:

     shell> mysql --host 85.224.35.45 --user
     `mysql: option '--user' requires an argument'

In this case, mysql was unable to find a value following the `--user'
option because nothing came after it on the command line. However, if
you omit the value for an option that is _not_ the last option to be
used, you obtain a different error that you may not be expecting:

     shell> mysql --host --user jon
     `ERROR 2005 (HY000): Unknown MySQL server host '--user' (1)'

Because `mysql' assumes that any string following `--host' on the
command line is a hostname, `--host --user' is interpreted as
`--host=--user', and the client attempts to connect to a MySQL server
running on a host named `--user'.

Options having default values always require an equals sign when
assigning a value; failing to do so causes an error. For example, the
MySQL server `--log-error' has the default value `HOST_NAME.err', where
HOST_NAME is the name of the host on which MySQL is running. Assume
that you are running MySQL on a computer whose hostname is `tonfisk',
and consider the following invocation of `mysqld_safe':

     shell> mysqld_safe &
     [1] 11699
     shell> 080112 12:53:40 mysqld_safe Logging to '/usr/local/mysql/var/tonfisk.err'.
     080112 12:53:40 mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql/var
     shell>

After shutting down the server, restart it as follows:

     shell> mysqld_safe --log-errors &
     [1] 11699
     shell> 080112 12:53:40 mysqld_safe Logging to '/usr/local/mysql/var/tonfisk.err'.
     080112 12:53:40 mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql/var
     shell>

The result is the same, since `--log-errors' is not followed by
anything else on the command line, and it supplies its own default
value. (The `&' character tells the operating system to run MySQL in the
background; it is ignored by MySQL itself.) Now suppose that you wish
to log errors to a file named `my-errors.err'. You might try starting
the server with `--log-error my-errors', but this does not have the
intended effect, as shown here:

     shell> mysqld_safe --log-error my-errors &
     [1] 31357
     shell> 080111 22:53:31 mysqld_safe Logging to '/usr/local/mysql/var/tonfisk.err'.
     080111 22:53:32 mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql/var
     080111 22:53:34 mysqld_safe mysqld from pid file /usr/local/mysql/var/tonfisk.pid ended

     [1]+  Done                    ./mysqld_safe --log-error my-errors

The server attempted to start using `/usr/local/mysql/var/tonfisk.err'
as the error log, but then shut down. Examining the last few lines of
this file shows the reason:

     shell> tail /usr/local/mysql/var/tonfisk.err
     080111 22:53:32  InnoDB: Started; log sequence number 0 46409
     `/usr/local/mysql/libexec/mysqld: Too many arguments (first extra is 'my-errors').
     Use --verbose --help to get a list of available options'
     080111 22:53:32 `[ERROR] Aborting'

     080111 22:53:32  InnoDB: Starting shutdown...
     080111 22:53:34  InnoDB: Shutdown completed; log sequence number 0 46409
     080111 22:53:34 [Note] /usr/local/mysql/libexec/mysqld: Shutdown complete

     080111 22:53:34 mysqld_safe mysqld from pid file /usr/local/mysql/var/tonfisk.pid ended

Because the `--log-error' option supplies a default value, you must use
an equals sign to assign a different value to it, as shown here:

     shell> mysqld_safe --log-error=my-errors &
     [1] 31437
     shell> 080111 22:54:15 mysqld_safe Logging to '/usr/local/mysql/var/my-errors.err'.
     080111 22:54:15 mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql/var

     shell>

Now the server has been started successfully, and is logging errors to
the file `/usr/local/mysql/var/my-errors.err'.

Similar issues can arise when specifying option values in option files.
For example, consider a `my.cnf' file that contains the following:

     [mysql]

     host
     user

When the `mysql' client reads this file, these entries are parsed as
`--host --user' or `--host=--user', with the result shown here:

     shell> mysql
     `ERROR 2005 (HY000): Unknown MySQL server host '--user' (1)'

Howver, in option files, an equals sign is not assumed. Suppose the
`my.cnf' file is as shown here:

     [mysql]

     user jon

Trying to start `mysql' in this case causes a different error:

     shell> mysql
     `mysql: unknown option '--user jon''

A similar error would occur if you were to write `host tonfisk' in the
option file rather than `host=tonfisk'. Instead, you must use the
equals sign:

     [mysql]

     user=jon

     shell> mysql
     Welcome to the MySQL monitor.  Commands end with ; or \g.
     Your MySQL connection id is 5
     Server version: 5.1.28 Source distribution

     Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

     mysql> SELECT USER();
     +---------------+
     | USER()        |
     +---------------+
     | jon@localhost |
     +---------------+
     1 row in set (0.00 sec)

This is not the same behavior as with the command line, where the
equals sign is not required:

     shell> mysql --user jon --host tonfisk
     Welcome to the MySQL monitor.  Commands end with ; or \g.
     Your MySQL connection id is 6
     Server version: 5.1.28 Source distribution

     Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

     mysql> SELECT USER();
     +---------------+
     | USER()        |
     +---------------+
     | jon@tonfisk   |
     +---------------+
     1 row in set (0.00 sec)


File: manual.info,  Node: setting-environment-variables,  Prev: program-options,  Up: programs-using

4.2.4 Setting Environment Variables
-----------------------------------

Environment variables can be set at the command prompt to affect the
current invocation of your command processor, or set permanently to
affect future invocations. To set a variable permanently, you can set
it in a startup file or by using the interface provided by your system
for this purpose. Consult the documentation for your command
interpreter for specific details.  *Note environment-variables::, lists
all environment variables that affect MySQL program operation.

To specify a value for an environment variable, use the syntax
appropriate for your command processor. For example, on Windows or
NetWare, you can set the `USER' variable to specify your MySQL account
name. To do so, use this syntax:

     SET USER=YOUR_NAME

The syntax on Unix depends on your shell. Suppose that you want to
specify the TCP/IP port number using the `MYSQL_TCP_PORT' variable.
Typical syntax (such as for `sh', `bash', `zsh', and so on) is as
follows:

     MYSQL_TCP_PORT=3306
     export MYSQL_TCP_PORT

The first command sets the variable, and the `export' command exports
the variable to the shell environment so that its value becomes
accessible to MySQL and other processes.

For `csh' and `tcsh', use `setenv' to make the shell variable available
to the environment:

     setenv MYSQL_TCP_PORT 3306

The commands to set environment variables can be executed at your
command prompt to take effect immediately, but the settings persist
only until you log out. To have the settings take effect each time you
log in, use the interface provided by your system or place the
appropriate command or commands in a startup file that your command
interpreter reads each time it starts.

On Windows, you can set environment variables using the System Control
Panel (under Advanced).

On Unix, typical shell startup files are `.bashrc' or `.bash_profile'
for `bash', or `.tcshrc' for `tcsh'.

Suppose that your MySQL programs are installed in
`/usr/local/mysql/bin' and that you want to make it easy to invoke
these programs. To do this, set the value of the `PATH' environment
variable to include that directory. For example, if your shell is
`bash', add the following line to your `.bashrc' file:

     PATH=${PATH}:/usr/local/mysql/bin

`bash' uses different startup files for login and non-login shells, so
you might want to add the setting to `.bashrc' for login shells and to
`.bash_profile' for non-login shells to make sure that `PATH' is set
regardless.

If your shell is `tcsh', add the following line to your `.tcshrc' file:

     setenv PATH ${PATH}:/usr/local/mysql/bin

If the appropriate startup file does not exist in your home directory,
create it with a text editor.

After modifying your `PATH' setting, open a new console window on
Windows or log in again on Unix so that the setting goes into effect.


File: manual.info,  Node: programs-server,  Next: programs-installation,  Prev: programs-using,  Up: programs

4.3 MySQL Server and Server-Startup Programs
============================================

* Menu:

* mysqld::                       `mysqld' --- The MySQL Server
* mysqld-safe::                  `mysqld_safe' --- MySQL Server Startup Script
* mysql-server::                 `mysql.server' --- MySQL Server Startup Script
* mysqld-multi::                 `mysqld_multi' --- Manage Multiple MySQL Servers

This section describes `mysqld', the MySQL server, and several programs
that are used to start the server.


File: manual.info,  Node: mysqld,  Next: mysqld-safe,  Prev: programs-server,  Up: programs-server

4.3.1 `mysqld' -- The MySQL Server
----------------------------------

`mysqld', also known as MySQL Server, is the main program that does
most of the work in a MySQL installation.  MySQL Server manages access
to the MySQL data directory that contains databases and tables. The
data directory is also the default location for other information such
as log files and status files.

When MySQL server starts, it listens for network connections from
client programs and manages access to databases on behalf of those
clients.

The `mysqld' program has many options that can be specified at startup.
For a complete list of options, run this command:

     shell> mysqld --verbose --help

MySQL Server also has a set of system variables that affect its
operation as it runs. System variables can be set at server startup,
and many of them can be changed at runtime to effect dynamic server
reconfiguration. MySQL Server also has a set of status variables that
provide information about its operation.  You can monitor these status
variables to access runtime performance characteristics.

For a full description of MySQL Server command options, system
variables, and status variables, see *Note mysqld-server::. For
information about installing MySQL and setting up the initial
configuration, see *Note installing::.


File: manual.info,  Node: mysqld-safe,  Next: mysql-server,  Prev: mysqld,  Up: programs-server

4.3.2 `mysqld_safe' -- MySQL Server Startup Script
--------------------------------------------------

`mysqld_safe' is the recommended way to start a `mysqld' server on Unix
and NetWare.  `mysqld_safe' adds some safety features such as
restarting the server when an error occurs and logging runtime
information to an error log file. Descriptions of error logging and
NetWare-specific behaviors are given later in this section.

*Note*:

In MySQL 5.1.20 (only), the default error logging behavior with
`mysqld_safe' is to write errors to `syslog' on systems that support the
`logger' program. This differs from the default behavior of writing an
error log file for other versions.

*In 5.1.20, logging to `syslog' may fail to operate correctly in some
cases, so we recommend that you use `--skip-syslog' to use the default
log file or `--log-error=FILE_NAME' to specify a log filename
explicitly.*

`mysqld_safe' tries to start an executable named `mysqld'. To override
the default behavior and specify explicitly the name of the server you
want to run, specify a `--mysqld' or `--mysqld-version' option to
`mysqld_safe'. You can also use `--ledir' to indicate the directory
where `mysqld_safe' should look for the server.

Many of the options to `mysqld_safe' are the same as the options to
`mysqld'. See *Note server-options::.

All options specified to `mysqld_safe' on the command line are passed
to `mysqld'. If you want to use any options that are specific to
`mysqld_safe' and that `mysqld' doesn't support, do not specify them on
the command line. Instead, list them in the `[mysqld_safe]' group of an
option file. See *Note option-files::.

`mysqld_safe' reads all options from the `[mysqld]', `[server]', and
`[mysqld_safe]' sections in option files. For example, if you specify a
`[mysqld]' section like this, `mysqld_safe' will find and use the
`--log-error' option:

     [mysqld]
     log-error=error.log

For backward compatibility, `mysqld_safe' also reads `[safe_mysqld]'
sections, although you should rename such sections to `[mysqld_safe]'
in MySQL 5.1 installations.

*`mysqld_safe' Option Reference*

*Format*       *Config File*  *Description*                        *Introduction*
-autoclose     autoclose      On NetWare, mysqld_safe provides a   
                              screen presence                      
-basedir=path  basedir        The path to the MySQL installation   
                              directory                            
-core-file-size=sizecore-file-size The size of the core file that       
                              mysqld should be able to create      
-datadir=path  datadir        The path to the data directory       
-defaults-extra-file=pathdefaults-extra-fileThe name of an option file to be     
                              read in addition to the usual        
                              option files                         
-defaults-file=file_namedefaults-file  The name of an option file to be     
                              read instead of the usual option     
                              files                                
-help                         Display a help message and exit      
-ledir=path    ledir          Use this option to indicate the      
                              pathname to the directory where      
                              the server is located                
-log-error=file_namelog-error      Write the error log to the given     
                              file                                 
-mysqld=prog_namemysqld         The name of the server program (in   
                              the ledir directory) that you  want  
                              to start                             
-mysqld-version=suffixmysqld-version This option is similar to the        
                              -mysqld option, but you specify      
                              only the suffix for the server       
                              program name                         
-nice=priority nice           Use the nice program to set the      
                              server's scheduling priority to      
                              the given value                      
-no-defaults   no-defaults    Do not read any option files         
-open-files-limit=countopen-files-limitThe number of files that mysqld      
                              should be able to open               
-pid-file      pid-file       The pathname of the process ID file  
-port=number   port           The port number that the server      
                              should use when listening for        
                              TCP/IP connections                   
-skip-kill-mysqldskip-kill-mysqldDo not try to kill stray mysqld      
                              processes                            
-skip-syslog   skip-syslog    Do not write error messages to       5.1.20
                              syslog; use error log file           
-socket=path   socket         The Unix socket file that the        
                              server should use when listening     
                              for  local connections               
-syslog        syslog         Write error messages to syslog       5.1.20
-timezone=timezonetimezone       Set the TZ time zone environment     
                              variable to the given option  value  
-user={user_name|user_id}user           Run the mysqld server as the user    
                              having the name user_name or the     
                              numeric user ID user_id              

`mysqld_safe' supports the following options:

   *  `--help'

     Display a help message and exit.

   *  `--autoclose'

     (NetWare only) On NetWare, `mysqld_safe' provides a screen
     presence. When you unload (shut down) the `mysqld_safe' NLM, the
     screen does not by default go away. Instead, it prompts for user
     input:

          *<NLM has terminated; Press any key to close the screen>*

     If you want NetWare to close the screen automatically instead, use
     the `--autoclose' option to `mysqld_safe'.

   *  `--basedir=PATH'

     The path to the MySQL installation directory.

   *  `--core-file-size=SIZE'

     The size of the core file that `mysqld' should be able to create.
     The option value is passed to `ulimit -c'.

   *  `--datadir=PATH'

     The path to the data directory.

   *  `--defaults-extra-file=PATH'

     The name of an option file to be read in addition to the usual
     option files. This must be the first option on the command line if
     it is used. If the file does not exist or is otherwise
     inaccessible, the server will exit with an error.

   *  `--defaults-file=FILE_NAME'

     The name of an option file to be read instead of the usual option
     files. This must be the first option on the command line if it is
     used.

   *  `--ledir=PATH'

     If `mysqld_safe' cannot find the server, use this option to
     indicate the pathname to the directory where the server is located.

   *  `--log-error=FILE_NAME'

     Write the error log to the given file. See *Note error-log::.

   *  `--mysqld=PROG_NAME'

     The name of the server program (in the `ledir' directory) that you
     want to start.  This option is needed if you use the MySQL binary
     distribution but have the data directory outside of the binary
     distribution. If `mysqld_safe' cannot find the server, use the
     `--ledir' option to indicate the pathname to the directory where
     the server is located.

   *  `--mysqld-version=SUFFIX'

     This option is similar to the `--mysqld' option, but you specify
     only the suffix for the server program name. The basename is
     assumed to be `mysqld'. For example, if you use
     `--mysqld-version=debug', `mysqld_safe' starts the `mysqld-debug'
     program in the `ledir' directory. If the argument to
     `--mysqld-version' is empty, `mysqld_safe' uses `mysqld' in the
     `ledir' directory.

   *  `--nice=PRIORITY'

     Use the `nice' program to set the server's scheduling priority to
     the given value.

   *  `--no-defaults'

     Do not read any option files. This must be the first option on the
     command line if it is used.

   *  `--open-files-limit=COUNT'

     The number of files that `mysqld' should be able to open. The
     option value is passed to `ulimit -n'. Note that you need to start
     `mysqld_safe' as `root' for this to work properly!

   *  `--pid-file=FILE_NAME'

     The pathname of the process ID file.

   *  `--port=PORT_NUM'

     The port number that the server should use when listening for
     TCP/IP connections. The port number must be 1024 or higher unless
     the server is started by the `root' system user.

   *  `--skip-kill-mysqld'

     Do not try to kill stray `mysqld' processes at startup. This
     option works only on Linux.

   *  `--socket=PATH'

     The Unix socket file that the server should use when listening for
     local connections.

   *  `--syslog', `--skip-syslog'

     `--syslog' causes error messages to be sent to `syslog' on systems
     that support the `logger' program.  `--skip-syslog' suppresses the
     use of `syslog'; messages are written to an error log file. These
     options were added in MySQL 5.1.20.

   *  `--syslog-tag=TAG'

     For logging to `syslog', messages from `mysqld_safe' and `mysqld'
     are written with a tag of `mysqld_safe' and `mysqld',
     respectively. To specify a suffix for the tag, use
     `--syslog-tag=TAG', which modifies the tags to be `mysqld_safe-TAG'
     and `mysqld-TAG'.  This option was added in MySQL 5.1.21.

   *  `--timezone=TIMEZONE'

     Set the `TZ' time zone environment variable to the given option
     value. Consult your operating system documentation for legal time
     zone specification formats.

   *  `--user={USER_NAME|USER_ID}'

     Run the `mysqld' server as the user having the name USER_NAME or
     the numeric user ID USER_ID.  (`User' in this context refers to a
     system login account, not a MySQL user listed in the grant tables.)

If you execute `mysqld_safe' with the `--defaults-file' or
`--defaults-extra-option' option to name an option file, the option
must be the first one given on the command line or the option file will
not be used. For example, this command will not use the named option
file:

     mysql> mysqld_safe --port=PORT_NUM --defaults-file=FILE_NAME

Instead, use the following command:

     mysql> mysqld_safe --defaults-file=FILE_NAME --port=PORT_NUM

The `mysqld_safe' script is written so that it normally can start a
server that was installed from either a source or a binary distribution
of MySQL, even though these types of distributions typically install
the server in slightly different locations. (See *Note
installation-layouts::.)  `mysqld_safe' expects one of the following
conditions to be true:

   * The server and databases can be found relative to the working
     directory (the directory from which `mysqld_safe' is invoked). For
     binary distributions, `mysqld_safe' looks under its working
     directory for `bin' and `data' directories. For source
     distributions, it looks for `libexec' and `var' directories. This
     condition should be met if you execute `mysqld_safe' from your
     MySQL installation directory (for example, `/usr/local/mysql' for
     a binary distribution).

   * If the server and databases cannot be found relative to the
     working directory, `mysqld_safe' attempts to locate them by
     absolute pathnames. Typical locations are `/usr/local/libexec' and
     `/usr/local/var'. The actual locations are determined from the
     values configured into the distribution at the time it was built.
     They should be correct if MySQL is installed in the location
     specified at configuration time.

Because `mysqld_safe' tries to find the server and databases relative
to its own working directory, you can install a binary distribution of
MySQL anywhere, as long as you run `mysqld_safe' from the MySQL
installation directory:

     shell> cd MYSQL_INSTALLATION_DIRECTORY
     shell> bin/mysqld_safe &

If `mysqld_safe' fails, even when invoked from the MySQL installation
directory, you can specify the `--ledir' and `--datadir' options to
indicate the directories in which the server and databases are located
on your system.

When you use `mysqld_safe' to start `mysqld', `mysqld_safe' arranges
for error (and notice) messages from itself and from `mysqld' to go to
the same destination.

As of MySQL 5.1.20, there are several `mysqld_safe' options for
controlling the destination of these messages:

   * `--syslog': Write error messages to `syslog' on systems that
     support the `logger' program.

   * `--skip-syslog': Do not write error messages to `syslog'. Messages
     are written to the default error log file (`HOST_NAME.err' in the
     data directory), or to a named file if the `--log-error' option is
     given.

   * `--log-error=FILE_NAME': Write error messages to the named error
     file.

If none of these options is given, the default is `--skip-syslog'.

*Note*:

In MySQL 5.1.20 `only', the default is `--syslog'. This differs from
logging behavior for other versions of MySQL, for which the default is
to write messages to the default error log file.

If `--syslog' and `--log-error' are both given, a warning is issued and
`--log-error' takes precedence.

When `mysqld_safe' writes a message, notices go to the logging
destination (`syslog' or the error log file) and `stdout'. Errors go to
the logging destination and `stderr'.

Before MySQL 5.1.20, error logging is controlled only with the
`--log-error' option. If it is given, messages go to the named error
file. Otherwise, messages go to the default error file.

Normally, you should not edit the `mysqld_safe' script. Instead,
configure `mysqld_safe' by using command-line options or options in the
`[mysqld_safe]' section of a `my.cnf' option file. In rare cases, it
might be necessary to edit `mysqld_safe' to get it to start the server
properly. However, if you do this, your modified version of
`mysqld_safe' might be overwritten if you upgrade MySQL in the future,
so you should make a copy of your edited version that you can reinstall.

On NetWare, `mysqld_safe' is a NetWare Loadable Module (NLM) that is
ported from the original Unix shell script.  It starts the server as
follows:

  1. Runs a number of system and option checks.

  2. Runs a check on `MyISAM' tables.

  3. Provides a screen presence for the MySQL server.

  4. Starts `mysqld', monitors it, and restarts it if it terminates in
     error.

  5. Sends error messages from `mysqld' to the `HOST_NAME.err' file in
     the data directory.

  6. Sends `mysqld_safe' screen output to the `HOST_NAME.safe' file in
     the data directory.


File: manual.info,  Node: mysql-server,  Next: mysqld-multi,  Prev: mysqld-safe,  Up: programs-server

4.3.3 `mysql.server' -- MySQL Server Startup Script
---------------------------------------------------

MySQL distributions on Unix include a script named `mysql.server'. It
can be used on systems such as Linux and Solaris that use System
V-style run directories to start and stop system services. It is also
used by the Mac OS X Startup Item for MySQL.

`mysql.server' can be found in the `support-files' directory under your
MySQL installation directory or in a MySQL source distribution.

If you use the Linux server RPM package (`MySQL-server-VERSION.rpm'),
the `mysql.server' script will be installed in the `/etc/init.d'
directory with the name `mysql'. You need not install it manually.  See
*Note linux-rpm::, for more information on the Linux RPM packages.

Some vendors provide RPM packages that install a startup script under a
different name such as `mysqld'.

If you install MySQL from a source distribution or using a binary
distribution format that does not install `mysql.server' automatically,
you can install it manually. Instructions are provided in *Note
automatic-start::.

`mysql.server' reads options from the `[mysql.server]' and `[mysqld]'
sections of option files. For backward compatibility, it also reads
`[mysql_server]' sections, although you should rename such sections to
`[mysql.server]' when using MySQL 5.1.

`mysql.server' understands the following options:

   * `--basedir=PATH'

     The path to the MySQL installation directory.

   * `--datadir=PATH'

     The path to the MySQL data directory.

   * `--pid-file=FILE_NAME'

     The pathname of the file in which the server should write its
     process ID.

   * `--service-startup-timeout=FILE_NAME'

     How long in seconds to wait for confirmation of server startup. If
     the server does not start within this time, `mysql.server' exits
     with an error. The default value is 900. A value of 0 means not to
     wait at all for startup. Negative values mean to wait forever (no
     timeout). This option was added in MySQL 5.1.17. Before that, a
     value of 900 is always used.

   * `--use-mysqld_safe'

     Use `mysqld_safe' to start the server. This is the default.

   * `--use-manager'

     Use Instance Manager to start the server.

   * `--user=USER_NAME'

     The login username to use for running `mysqld'.


File: manual.info,  Node: mysqld-multi,  Prev: mysql-server,  Up: programs-server

4.3.4 `mysqld_multi' -- Manage Multiple MySQL Servers
-----------------------------------------------------

`mysqld_multi' is designed to manage several `mysqld' processes that
listen for connections on different Unix socket files and TCP/IP ports.
It can start or stop servers, or report their current status. The MySQL
Instance Manager is an alternative means of managing multiple servers
(see *Note instance-manager::).

`mysqld_multi' searches for groups named `[mysqldN]' in `my.cnf' (or in
the file named by the `--config-file' option).  N can be any positive
integer. This number is referred to in the following discussion as the
option group number, or GNR. Group numbers distinguish option groups
from one another and are used as arguments to `mysqld_multi' to specify
which servers you want to start, stop, or obtain a status report for.
Options listed in these groups are the same that you would use in the
`[mysqld]' group used for starting `mysqld'. (See, for example, *Note
automatic-start::.) However, when using multiple servers, it is
necessary that each one use its own value for options such as the Unix
socket file and TCP/IP port number. For more information on which
options must be unique per server in a multiple-server environment, see
*Note multiple-servers::.

To invoke `mysqld_multi', use the following syntax:

     shell> mysqld_multi [OPTIONS] {start|stop|report} [GNR[,GNR] ...]

`start', `stop', and `report' indicate which operation to perform.  You
can perform the designated operation for a single server or multiple
servers, depending on the GNR list that follows the option name. If
there is no list, `mysqld_multi' performs the operation for all servers
in the option file.

Each GNR value represents an option group number or range of group
numbers. The value should be the number at the end of the group name in
the option file. For example, the GNR for a group named `[mysqld17]' is
`17'. To specify a range of numbers, separate the first and last numbers
by a dash. The GNR value `10-13' represents groups `[mysqld10]' through
`[mysqld13]'. Multiple groups or group ranges can be specified on the
command line, separated by commas. There must be no whitespace
characters (spaces or tabs) in the GNR list; anything after a whitespace
character is ignored.

This command starts a single server using option group `[mysqld17]':

     shell> mysqld_multi start 17

This command stops several servers, using option groups `[mysqld8]' and
`[mysqld10]' through `[mysqld13]':

     shell> mysqld_multi stop 8,10-13

For an example of how you might set up an option file, use this command:

     shell> mysqld_multi --example

As of MySQL 5.1.18, `mysqld_multi' searches for option files as follows:

   * With `--no-defaults', no option files are read.

   * With `--defaults-file=FILE_NAME', only the named file is read.

   * Otherwise, option files in the standard list of locations are
     read, including any file named by the
     `--defaults-extra-file=FILE_NAME' option, if one is given. (If the
     option is given multiple times, the last value is used.)

Option files read are searched for `[mysqld_multi]' and `[mysqldN]'
option groups.

Before MySQL 5.1.18, the preceding options are not recognized.  Files
in the standard locations are read, and any file named by the
`--config-file=FILE_NAME' option, if one is given. A file named by
`--config-file' is read only for `[mysqldN]' option groups, not the
`[mysqld_multi]' group.

`mysqld_multi' supports the following options:

   * `--help'

     Display a help message and exit.

   * `--config-file=FILE_NAME'

     As of MySQL 5.1.18, this option is deprecated. If given, it is
     treated the same way as `--defaults-extra-file', described earlier.

     Before MySQL 5.1.18, this option specifies the name of an extra
     option file. It affects where `mysqld_multi' looks for `[mysqldN]'
     option groups. Without this option, all options are read from the
     usual `my.cnf' file. The option does not affect where
     `mysqld_multi' reads its own options, which are always taken from
     the `[mysqld_multi]' group in the usual `my.cnf' file.

   * `--example'

     Display a sample option file.

   * `--log=FILE_NAME'

     Specify the name of the log file. If the file exists, log output
     is appended to it.

   * `--mysqladmin=PROG_NAME'

     The `mysqladmin' binary to be used to stop servers.

   * `--mysqld=PROG_NAME'

     The `mysqld' binary to be used. Note that you can specify
     `mysqld_safe' as the value for this option also. If you use
     `mysqld_safe' to start the server, you can include the `mysqld' or
     `ledir' options in the corresponding `[mysqldN]' option group.
     These options indicate the name of the server that `mysqld_safe'
     should start and the pathname of the directory where the server is
     located. (See the descriptions for these options in *Note
     mysqld-safe::.) Example:

          [mysqld38]
          mysqld = mysqld-debug
          ledir  = /opt/local/mysql/libexec

   * `--no-log'

     Print log information to `stdout' rather than to the log file. By
     default, output goes to the log file.

   * `--password=PASSWORD'

     The password of the MySQL account to use when invoking
     `mysqladmin'. Note that the password value is not optional for
     this option, unlike for other MySQL programs.

   * `--silent'

     Silent mode; disable warnings.

   * `--tcp-ip'

     Connect to each MySQL server via the TCP/IP port instead of the
     Unix socket file. (If a socket file is missing, the server might
     still be running, but accessible only via the TCP/IP port.) By
     default, connections are made using the Unix socket file. This
     option affects `stop' and `report' operations.

   * `--user=USER_NAME'

     The username of the MySQL account to use when invoking
     `mysqladmin'.

   *  `--verbose'

     Be more verbose.

   * `--version'

     Display version information and exit.

Some notes about `mysqld_multi':

   * *Most important*: Before using `mysqld_multi' be sure that you
     understand the meanings of the options that are passed to the
     `mysqld' servers and _why_ you would want to have separate
     `mysqld' processes. Beware of the dangers of using multiple
     `mysqld' servers with the same data directory. Use separate data
     directories, unless you _know_ what you are doing. Starting
     multiple servers with the same data directory does _not_ give you
     extra performance in a threaded system. See *Note
     multiple-servers::.

   * *Important*:

     Make sure that the data directory for each server is fully
     accessible to the Unix account that the specific `mysqld' process
     is started as.  _Do not_ use the Unix ROOT account for this, unless
     you _know_ what you are doing. See *Note changing-mysql-user::.

   * Make sure that the MySQL account used for stopping the `mysqld'
     servers (with the `mysqladmin' program) has the same username and
     password for each server. Also, make sure that the account has the
     `SHUTDOWN' privilege. If the servers that you want to manage have
     different usernames or passwords for the administrative accounts,
     you might want to create an account on each server that has the
     same username and password. For example, you might set up a common
     `multi_admin' account by executing the following commands for each
     server:

          shell> mysql -u root -S /tmp/mysql.sock -p
          Enter password:
          mysql> GRANT SHUTDOWN ON *.*
              -> TO 'multi_admin'@'localhost' IDENTIFIED BY 'multipass';

     See *Note privileges::. You have to do this for each `mysqld'
     server. Change the connection parameters appropriately when
     connecting to each one. Note that the hostname part of the account
     name must allow you to connect as `multi_admin' from the host
     where you want to run `mysqld_multi'.

   * The Unix socket file and the TCP/IP port number must be different
     for every `mysqld'.  (Alternatively, if the host has multiple
     network addresses, you can use `--bind-adress' to cause different
     servers to listen to different interfaces.)

   * The `--pid-file' option is very important if you are using
     `mysqld_safe' to start `mysqld' (for example,
     `--mysqld=mysqld_safe') Every `mysqld' should have its own process
     ID file. The advantage of using `mysqld_safe' instead of `mysqld'
     is that `mysqld_safe' monitors its `mysqld' process and restarts
     it if the process terminates due to a signal sent using `kill -9'
     or for other reasons, such as a segmentation fault. Please note
     that the `mysqld_safe' script might require that you start it from
     a certain place.  This means that you might have to change
     location to a certain directory before running `mysqld_multi'. If
     you have problems starting, please see the `mysqld_safe' script.
     Check especially the lines:

          ----------------------------------------------------------------
          MY_PWD=`pwd`
          # Check if we are starting this relative (for the binary release)
          if test -d $MY_PWD/data/mysql -a \
             -f ./share/mysql/english/errmsg.sys -a \
             -x ./bin/mysqld
          ----------------------------------------------------------------

     The test performed by these lines should be successful, or you
     might encounter problems. See *Note mysqld-safe::.

   * You might want to use the `--user' option for `mysqld', but to do
     this you need to run the `mysqld_multi' script as the Unix `root'
     user. Having the option in the option file doesn't matter; you
     just get a warning if you are not the superuser and the `mysqld'
     processes are started under your own Unix account.

The following example shows how you might set up an option file for use
with `mysqld_multi'. The order in which the `mysqld' programs are
started or stopped depends on the order in which they appear in the
option file.  Group numbers need not form an unbroken sequence. The
first and fifth `[mysqldN]' groups were intentionally omitted from the
example to illustrate that you can have `gaps' in the option file. This
gives you more flexibility.

     # This file should probably be in your home dir (~/.my.cnf)
     # or /etc/my.cnf
     # Version 2.1 by Jani Tolonen

     [mysqld_multi]
     mysqld     = /usr/local/bin/mysqld_safe
     mysqladmin = /usr/local/bin/mysqladmin
     user       = multi_admin
     password   = multipass

     [mysqld2]
     socket     = /tmp/mysql.sock2
     port       = 3307
     pid-file   = /usr/local/mysql/var2/hostname.pid2
     datadir    = /usr/local/mysql/var2
     language   = /usr/local/share/mysql/english
     user       = john

     [mysqld3]
     socket     = /tmp/mysql.sock3
     port       = 3308
     pid-file   = /usr/local/mysql/var3/hostname.pid3
     datadir    = /usr/local/mysql/var3
     language   = /usr/local/share/mysql/swedish
     user       = monty

     [mysqld4]
     socket     = /tmp/mysql.sock4
     port       = 3309
     pid-file   = /usr/local/mysql/var4/hostname.pid4
     datadir    = /usr/local/mysql/var4
     language   = /usr/local/share/mysql/estonia
     user       = tonu

     [mysqld6]
     socket     = /tmp/mysql.sock6
     port       = 3311
     pid-file   = /usr/local/mysql/var6/hostname.pid6
     datadir    = /usr/local/mysql/var6
     language   = /usr/local/share/mysql/japanese
     user       = jani

See *Note option-files::.


File: manual.info,  Node: programs-installation,  Next: programs-client,  Prev: programs-server,  Up: programs

4.4 MySQL Installation-Related Programs
=======================================

* Menu:

* comp-err::                     `comp_err' --- Compile MySQL Error Message File
* make-win-bin-dist::            `make_win_bin_dist' --- Package MySQL Distribution as ZIP Archive
* mysqlbug::                     `mysqlbug' --- Generate Bug Report
* mysql-fix-privilege-tables::   `mysql_fix_privilege_tables' --- Upgrade MySQL System Tables
* mysql-install-db::             `mysql_install_db' --- Initialize MySQL Data Directory
* mysql-secure-installation::    `mysql_secure_installation' --- Improve MySQL Installation Security
* mysql-tzinfo-to-sql::          `mysql_tzinfo_to_sql' --- Load the Time Zone Tables
* mysql-upgrade::                `mysql_upgrade' --- Check Tables for MySQL Upgrade

The programs in this section are used when installing or upgrading
MySQL.


File: manual.info,  Node: comp-err,  Next: make-win-bin-dist,  Prev: programs-installation,  Up: programs-installation

4.4.1 `comp_err' -- Compile MySQL Error Message File
----------------------------------------------------

`comp_err' creates the `errmsg.sys' file that is used by `mysqld' to
determine the error messages to display for different error codes.
`comp_err' normally is run automatically when MySQL is built. It
compiles the `errmsg.sys' file from the plaintext file located at
`sql/share/errmsg.txt' in MySQL source distributions.

`comp_err' also generates `mysqld_error.h', `mysqld_ername.h', and
`sql_state.h' header files.

For more information about how error messages are defined, see the
MySQL Internals Manual.

Invoke `comp_err' like this:

     shell> comp_err [OPTIONS]

`comp_err' understands the options described in the following list.

   * `--help', `-?'

     Display a help message and exit.

   * `--charset=PATH, -C PATH'

     The character set directory. The default is
     `../sql/share/charsets'.

   * `--debug=DEBUG_OPTIONS, -# DEBUG_OPTIONS'

     Write a debugging log. The DEBUG_OPTIONS string often is
     `'d:t:O,FILE_NAME''.  The default is `'d:t:O,/tmp/comp_err.trace''.

   * `--debug-info', `-T'

     Print some debugging information when the program exits.

   * `--header_file=FILE_NAME, -H FILE_NAME'

     The name of the error header file. The default is `mysqld_error.h'.

   * `--in_file=FILE_NAME, -F FILE_NAME'

     The name of the input file. The default is
     `../sql/share/errmsg.txt'.

   * `--name_file=FILE_NAME, -N FILE_NAME'

     The name of the error name file. The default is `mysqld_ername.h'.

   * `--out_dir=PATH, -D PATH'

     The name of the output base directory. The default is
     `../sql/share/'.

   * `--out_file=FILE_NAME, -O FILE_NAME'

     The name of the output file. The default is `errmsg.sys'.

   * `--statefile=FILE_NAME, -S FILE_NAME'

     The name for the SQLSTATE header file. The default is
     `sql_state.h'.

   * `--version', `-V'

     Display version information and exit.


File: manual.info,  Node: make-win-bin-dist,  Next: mysqlbug,  Prev: comp-err,  Up: programs-installation

4.4.2 `make_win_bin_dist' -- Package MySQL Distribution as ZIP Archive
----------------------------------------------------------------------

This script is used on Windows after building a MySQL distribution from
source to create executable programs. It packages the binaries and
support files into a ZIP archive that can be unpacked at the location
where you want to install MySQL.

`make_win_bin_dist' is a shell script, so you must have Cygwin
installed to use it.

This program's use is subject to change. Currently, you invoke it as
follows from the root directory of your source distribution:

     shell> make_win_bin_dist [OPTIONS] PACKAGE_BASENAME [COPY_DEF ...]

The PACKAGE_BASENAME argument provides the basename for the resulting
ZIP archive. This name will be the name of the directory that results
from unpacking the archive.

Because you might want to include files of directories from other
builds, you can instruct this script do copy them in for you, via
COPY_DEF arguments, which of which is of the form
RELATIVE_DEST_NAME=SOURCE_NAME.

Example:

     bin/mysqld-max.exe=../my-max-build/sql/release/mysqld.exe

If you specify a directory, the entire directory will be copied.

`make_win_bin_dist' understands the following options:

   * `--debug'

     Pack the debug binaries and produce an error if they were not
     built.

   * `--embedded'

     Pack the embedded server and produce an error if it was not built.
     The default is to pack it if it was built.

   * `--exe-suffix=SUFFIX'

     Add a suffix to the basename of the `mysql' binary. For example, a
     suffix of `-abc' produces a binary named `mysqld-abc.exe'.

   * `--no-debug'

     Don't pack the debug binaries even if they were built.

   * `--no-embedded'

     Don't pack the embedded server even if it was built.

   * `--only-debug'

     Use this option when the target for this build was `Debug', and
     you just want to replace the normal binaries with debug versions
     (that is, do not use separate `debug' directories).


File: manual.info,  Node: mysqlbug,  Next: mysql-fix-privilege-tables,  Prev: make-win-bin-dist,  Up: programs-installation

4.4.3 `mysqlbug' -- Generate Bug Report
---------------------------------------

This program enables you to generate a bug report and send it to MySQL
AB. It is a shell script and runs on Unix.

The normal way to report bugs is to visit `http://bugs.mysql.com/',
which is the address for our bugs database. This database is public and
can be browsed and searched by anyone. If you log in to the system, you
can enter new reports. If you have no Web access, you can generate a
bug report by using the `mysqlbug' script.

`mysqlbug' helps you generate a report by determining much of the
following information automatically, but if something important is
missing, please include it with your message. `mysqlbug' can be found
in the `scripts' directory (source distribution) and in the `bin'
directory under your MySQL installation directory (binary distribution).

Invoke `mysqlbug' without arguments:

     shell> mysqlbug

The script will place you in an editor with a copy of the report to be
sent. Edit the lines near the beginning that indicate the nature of the
problem. Then write the file to save your changes, quit the editor, and
`mysqlbug' will send the report by email. perform.


File: manual.info,  Node: mysql-fix-privilege-tables,  Next: mysql-install-db,  Prev: mysqlbug,  Up: programs-installation

4.4.4 `mysql_fix_privilege_tables' -- Upgrade MySQL System Tables
-----------------------------------------------------------------

Some releases of MySQL introduce changes to the structure of the system
tables in the `mysql' database to add new privileges or support new
features. When you update to a new version of MySQL, you should update
your system tables as well to make sure that their structure is up to
date. Otherwise, there might be capabilities that you cannot take
advantage of.  First, make a backup of your `mysql' database, and then
use the following procedure.

*Note*:

As of MySQL 5.1.7, `mysql_fix_privilege_tables' is superseded by
`mysql_upgrade', which should be used instead. See *Note
mysql-upgrade::.

On Unix or Unix-like systems, update the system tables by running the
`mysql_fix_privilege_tables' script:

     shell> mysql_fix_privilege_tables

You must run this script while the server is running. It attempts to
connect to the server running on the local host as `root'. If your
`root' account requires a password, indicate the password on the
command line like this:

     shell> mysql_fix_privilege_tables --password=ROOT_PASSWORD

The `mysql_fix_privilege_tables' script performs any actions necessary
to convert your system tables to the current format. You might see some
`Duplicate column name' warnings as it runs; you can ignore them.

After running the script, stop the server and restart it so that it
uses any changes that were made to the system tables.

On Windows systems, MySQL distributions include a
`mysql_fix_privilege_tables.sql' SQL script that you can run using the
`mysql' client. For example, if your MySQL installation is located at
`C:\Program Files\MySQL\MySQL Server 5.1', the commands look like this:

     C:\> cd "C:\Program Files\MySQL\MySQL Server 5.1"
     C:\> bin\mysql -u root -p mysql
     mysql> SOURCE share/mysql_fix_privilege_tables.sql

*Note*:

Prior to version 5.1.17, this script is found in the `scripts'
directory.

The `mysql' command will prompt you for the `root' password; enter it
when prompted.

If your installation is located in some other directory, adjust the
pathnames appropriately.

As with the Unix procedure, you might see some `Duplicate column name'
warnings as `mysql' processes the statements in the
`mysql_fix_privilege_tables.sql' script; you can ignore them.

After running the script, stop the server and restart it.


File: manual.info,  Node: mysql-install-db,  Next: mysql-secure-installation,  Prev: mysql-fix-privilege-tables,  Up: programs-installation

4.4.5 `mysql_install_db' -- Initialize MySQL Data Directory
-----------------------------------------------------------

`mysql_install_db' initializes the MySQL data directory and creates the
system tables that it contains, if they do not exist. Because the MySQL
server, `mysqld', needs to access the data directory when it runs
later, you should either run `mysql_install_db' from the same account
that will be used for running `mysqld' or run it as `root' and use the
`--user' option to indicate the username that `mysqld' will run as.

To invoke `mysql_install_db', use the following syntax:

     shell> mysql_install_db [OPTIONS]

`mysql_install_db' needs to invoke `mysqld' with the `--bootstrap' and
`--skip-grant-tables' options (see *Note configure-options::). If MySQL
was configured with the `--disable-grant-options' option, `--bootstrap'
and `--skip-grant-tables' will be disabled. To handle this, set the
`MYSQLD_BOOTSTRAP' environment variable to the full pathname of a
server that has all options enabled. `mysql_install_db' will use that
server.

`mysql_install_db' supports the following options:

   * `--basedir=PATH'

     The path to the MySQL installation directory.

   * `--force'

     Causes `mysql_install_db' to run even if DNS does not work. In
     that case, grant table entries that normally use hostnames will
     use IP addresses.

   * `--datadir=PATH', `--ldata=PATH'

     The path to the MySQL data directory.

   * `--rpm'

     For internal use. This option is used by RPM files during the
     MySQL installation process.

   * `--skip-name-resolve'

     Use IP addresses rather than hostnames when creating grant table
     entries. This option can be useful if your DNS does not work.

   * `--srcdir=PATH'

     For internal use. The directory under which `mysql_install_db'
     looks for support files such as the error message file and the
     file for populating the help tables. This option was added in
     MySQL 5.1.14.

   * `--user=USER_NAME'

     The login username to use for running `mysqld'. Files and
     directories created by `mysqld' will be owned by this user. You
     must be `root' to use this option. By default, `mysqld' runs using
     your current login name and files and directories that it creates
     will be owned by you.

   * `--verbose'

     Verbose mode. Print more information about what the program does.

   * `--windows'

     For internal use. This option is used for creating Windows
     distributions.


File: manual.info,  Node: mysql-secure-installation,  Next: mysql-tzinfo-to-sql,  Prev: mysql-install-db,  Up: programs-installation

4.4.6 `mysql_secure_installation' -- Improve MySQL Installation Security
------------------------------------------------------------------------

This program enables you to improve the security of your MySQL
installation in the following ways:

   * You can set a password for `root' accounts.

   * You can remove `root' accounts that are accessible from outside
     the local host.

   * You can remove anonymous-user accounts.

   * You can remove the `test' database, which by default can be
     accessed by anonymous users.

Invoke `mysql_secure_installation' without arguments:

     shell> mysql_secure_installation

The script will prompt you to determine which actions to perform.


File: manual.info,  Node: mysql-tzinfo-to-sql,  Next: mysql-upgrade,  Prev: mysql-secure-installation,  Up: programs-installation

4.4.7 `mysql_tzinfo_to_sql' -- Load the Time Zone Tables
--------------------------------------------------------

The `mysql_tzinfo_to_sql' program loads the time zone tables in the
`mysql' database. It is used on systems that have a _zoneinfo_ database
(the set of files describing time zones). Examples of such systems are
Linux, FreeBSD, Sun Solaris, and Mac OS X. One likely location for
these files is the `/usr/share/zoneinfo' directory
(`/usr/share/lib/zoneinfo' on Solaris). If your system does not have a
zoneinfo database, you can use the downloadable package described in
*Note time-zone-support::.

`mysql_tzinfo_to_sql' can be invoked several ways:

     shell> mysql_tzinfo_to_sql TZ_DIR
     shell> mysql_tzinfo_to_sql TZ_FILE TZ_NAME
     shell> mysql_tzinfo_to_sql --leap TZ_FILE

For the first invocation syntax, pass the zoneinfo directory pathname
to `mysql_tzinfo_to_sql' and send the output into the `mysql' program.
For example:

     shell> mysql_tzinfo_to_sql /usr/share/zoneinfo | mysql -u root mysql

`mysql_tzinfo_to_sql' reads your system's time zone files and generates
SQL statements from them.  `mysql' processes those statements to load
the time zone tables.

The second syntax causes `mysql_tzinfo_to_sql' to load a single time
zone file TZ_FILE that corresponds to a time zone name TZ_NAME:

     shell> mysql_tzinfo_to_sql TZ_FILE TZ_NAME | mysql -u root mysql

If your time zone needs to account for leap seconds, invoke
`mysql_tzinfo_to_sql' using the third syntax, which initializes the
leap second information.  TZ_FILE is the name of your time zone file:

     shell> mysql_tzinfo_to_sql --leap TZ_FILE | mysql -u root mysql

After running `mysql_tzinfo_to_sql', it is best to restart the server
so that it does not continue to use any previously cached time zone
data.


File: manual.info,  Node: mysql-upgrade,  Prev: mysql-tzinfo-to-sql,  Up: programs-installation

4.4.8 `mysql_upgrade' -- Check Tables for MySQL Upgrade
-------------------------------------------------------

`mysql_upgrade' should be executed each time you upgrade MySQL. It
checks all tables in all databases for incompatibilities with the
current version of MySQL Server. If a table is found to have a possible
incompatibility, it is checked. If any problems are found, the table is
repaired.  `mysql_upgrade' also upgrades the system tables so that you
can take advantage of new privileges or capabilities that might have
been added.

All checked and repaired tables are marked with the current MySQL
version number. This ensures that next time you run `mysql_upgrade'
with the same version of the server, it can tell whether there is any
need to check or repair the table again.

`mysql_upgrade' also saves the MySQL version number in a file named
`mysql_upgrade_info' in the data directory. This is used to quickly
check if all tables have been checked for this release so that
table-checking can be skipped. To ignore this file, use the `--force'
option.

*Caution*:

Some upgrade incompatibilities may require special handling _before_
you upgrade your MySQL installation and run `mysql_upgrade'. See *Note
upgrade::, for instructions on determining whether any such
incompatibilies apply to your installation and how to handle them.

To check and repair tables and to upgrade the system tables,
`mysql_upgrade' executes the following commands:

     mysqlcheck --check-upgrade --all-databases --auto-repair
     mysql_fix_privilege_tables

`mysql_upgrade' supersedes the older `mysql_fix_privilege_tables'
script. In MySQL 5.1.7, `mysql_upgrade ' was added as a shell script
and worked only for Unix systems. As of MySQL 5.1.10, `mysql_upgrade'
is an executable binary and is available on all systems. On systems
older than those supporting `mysql_upgrade', you can execute the
`mysqlcheck' command manually, and then upgrade your system tables as
described in *Note mysql-fix-privilege-tables::.

If you install MySQL from RPM packages on Linux, you must install the
server and client RPMs.  `mysql_upgrade' is included in the server RPM
but requires the client RPM because the latter includes `mysqlcheck'.
(See *Note linux-rpm::.)

For details about what is checked, see the description of the `FOR
UPGRADE' option of the `CHECK TABLE' statement (see *Note
check-table::).

To use `mysql_upgrade', make sure that the server is running, and then
invoke it like this:

     shell> mysql_upgrade [OPTIONS]

After running `mysql_upgrade', stop the server and restart it so that
it uses any changes that were made to the system tables.

`mysql_upgrade' reads options from the command line and from the
`[mysql_upgrade]' group in option files. It supports the options in the
following list.  Other options are passed to `mysqlcheck' and to
`mysql_fix_privilege_tables'. For example, it might be necessary to
specify the `--password[=PASSWORD]' option.

   * `--help'

     Display a short help message and exit.

   * `--basedir=PATH'

     The path to the MySQL installation directory.

   * `--datadir=PATH'

     The path to the data directory.

   *  `--debug-check'

     Print some debugging information when the program exits.  This
     option was added in MySQL 5.1.21.

   *  `--debug-info', `-T'

     Print debugging information and memory and CPU usage statistics
     when the program exits. This option was added in MySQL 5.1.21.

   * `--force'

     Force execution of `mysqlcheck' even if `mysql_upgrade' has
     already been executed for the current version of MySQL. (In other
     words, this option causes the `mysql_upgrade_info' file to be
     ignored.)

   * `--tmpdir=PATH', `-t PATH'

     The pathname of the directory to use for creating temporary files.
     This option was added in MySQL 5.1.25.

   * `--user=USER_NAME', `-u USER_NAME'

     The MySQL username to use when connecting to the server. The
     default username is `root'.

   * `--verbose'

     Verbose mode. Print more information about what the program does.


File: manual.info,  Node: programs-client,  Next: programs-admin-utils,  Prev: programs-installation,  Up: programs

4.5 MySQL Client Programs
=========================

* Menu:

* mysql::                        `mysql' --- The MySQL Command-Line Tool
* mysqladmin::                   `mysqladmin' --- Client for Administering a MySQL Server
* mysqlcheck::                   `mysqlcheck' --- A Table Maintenance and Repair Program
* mysqldump::                    `mysqldump' --- A Database Backup Program
* mysqlimport::                  `mysqlimport' --- A Data Import Program
* mysqlshow::                    `mysqlshow' --- Display Database, Table, and Column Information
* mysqlslap::                    `mysqlslap' --- Load Emulation Client


File: manual.info,  Node: mysql,  Next: mysqladmin,  Prev: programs-client,  Up: programs-client

4.5.1 `mysql' -- The MySQL Command-Line Tool
--------------------------------------------

* Menu:

* mysql-command-options::        `mysql' Options
* mysql-commands::               `mysql' Commands
* mysql-server-side-help::       `mysql' Server-Side Help
* batch-commands::               Executing SQL Statements from a Text File
* mysql-tips::                   `mysql' Tips

`mysql' is a simple SQL shell (with GNU `readline' capabilities). It
supports interactive and non-interactive use. When used interactively,
query results are presented in an ASCII-table format. When used
non-interactively (for example, as a filter), the result is presented
in tab-separated format. The output format can be changed using command
options.

If you have problems due to insufficient memory for large result sets,
use the `--quick' option. This forces `mysql' to retrieve results from
the server a row at a time rather than retrieving the entire result set
and buffering it in memory before displaying it. This is done by
returning the result set using the *Note `mysql_use_result()':
mysql-use-result. C API function in the client/server library rather
than *Note `mysql_store_result()': mysql-store-result.

Using `mysql' is very easy. Invoke it from the prompt of your command
interpreter as follows:

     shell> mysql DB_NAME

Or:

     shell> mysql --user=USER_NAME --password=YOUR_PASSWORD DB_NAME

Then type an SQL statement, end it with ``;'', `\g', or `\G' and press
Enter.

As of MySQL 5.1.10, typing Control-C causes `mysql' to attempt to kill
the current statement. If this cannot be done, or Control-C is typed
again before the statement is killed, `mysql' exits.  Previously,
Control-C caused `mysql' to exit in all cases.

You can execute SQL statements in a script file (batch file) like this:

     shell> mysql DB_NAME < SCRIPT.SQL > OUTPUT.TAB


File: manual.info,  Node: mysql-command-options,  Next: mysql-commands,  Prev: mysql,  Up: mysql

4.5.1.1 `mysql' Options
.......................

*`mysql' Option Reference*

*Format*       *Config File*  *Description*                        *Introduction*
-auto-rehash   auto-rehash    Enable automatic rehashing           
-batch         batch          Don't use history file               
-bind-address=host_name               Determine which client network       5.1.22-ndb-6.3.4
                              interface (IP address or hostname)   
                              to use when connecting to the MySQL  
                              Server                               
-character-sets-dir=namecharacter-sets-dirSet the default character set        
-column-names  column-names   Write column names in results        
-column-type-infocolumn-type-infoDisplay result set metadata          5.1.14
-comments      comments       Whether to retain or strip comments  5.1.23
                              in statements sent to the  server    
-compress      compress       Compress all information sent        
                              between the client and the server    
-connect_timeout=valueconnect_timeoutThe number of seconds before         
                              connection timeout                   
-database=dbnamedatabase       The database to use                  
-debug[=debug_options]debug          Write a debugging log                
-debug-check   debug-check    Print debugging information when     5.1.21
                              the program exits                    
-debug-info    debug-info     Print debugging information, memory  
                              and CPU statistics when the          
                              program exits                        
-default-character-set=charset_namedefault-character-setUse charset_name as the default      
                              character set                        
-delimiter=str delimiter      Set the statement delimiter          
-execute=statementexecute        Execute the statement and quit       
-force         force          Continue even if an SQL error occurs 
-help                         Display help message and exit        
-host=host_namehost           Connect to the MySQL server on the   
                              given host                           
-html          html           Produce HTML output                  
-ignore-spaces ignore-spaces  Ignore spaces after function names   
-line-numbers  line-numbers   Write line numbers for errors        
-local-infile[={0|1}]local-infile   Enable or disable for LOCAL          
                              capability for LOAD DATA INFILE      
-max_allowed_packet=valuemax_allowed_packetThe maximum packet length to send    
                              to or receive from the server        
-max_join_size=valuemax_join_size  The automatic limit for rows in a    
                              join when using -safe-updates        
-named-commandsnamed-commands Enable named mysql commands          
-net_buffer_length=valuenet_buffer_lengthThe buffer size for TCP/IP and       
                              socket communication                 
-no-auto-rehash               Disable automatic rehashing          
-no-beep       no-beep        Do not beep when errors occur        
-no-named-commandsno-named-commandsDisable named mysql commands         
-no-pager      no-pager       Deprecated form of -skip-pager       
-no-tee        no-tee         Do not copy output to a file         
-one-database  one-database   Ignore statements except those for   
                              the default database named on  the   
                              command line                         
-pager[=command]pager          Use the given command for paging     
                              query output                         
-password[=password]password       The password to use when connecting  
                              to the server                        
-port=port_num port           The TCP/IP port number to use for    
                              the connection                       
-prompt=format_strprompt         Set the prompt to the specified      
                              format                               
-protocol=type protocol       The connection protocol to use       
-quick         quick          Do not cache each query result       
-raw           raw            Write column values without escape   
                              conversion                           
-reconnect     reconnect      If the connection to the server is   
                              lost, automatically try to           
                              reconnect                            
-safe-updates  safe-updates   Allow only UPDATE and DELETE         
                              statements that specify key values   
-secure-auth   secure-auth    Do not send passwords to the server  
                              in old (pre-4.1.1) format            
-select_limit=valueselect_limit   The automatic limit for SELECT       
                              statements when using  -safe-updates 
-show-warnings show-warnings  Show warnings after each statement   
                              if there are any                     
-sigint-ignore sigint-ignore  Ignore SIGINT signals (typically     
                              the result of typing Control-C)      
-silent        silent         Silent mode                          
-skip-auto-rehashskip-auto-rehashDisable automatic rehashing          
-skip-column-namesskip-column-namesDo not write column names in results 
-skip-line-numbersskip-line-numbersSkip line numbers for errors         
-skip-named-commandsskip-named-commandsDisable named mysql commands         
-skip-pager    skip-pager     Disable paging                       
-skip-reconnectskip-reconnect Disable reconnecting                 
-socket=path   socket         For connections to localhost         
-ssl-ca=file_namessl-ca         The path to a file that contains a   
                              list of trusted SSL CAs              
-ssl-capath=directory_namessl-capath     The path to a directory that         
                              contains trusted SSL CA              
                              certificates  in PEM format          
-ssl-cert=file_namessl-cert       The name of the SSL certificate      
                              file to use for establishing a       
                              secure connection                    
-ssl-cipher=cipher_listssl-cipher     A list of allowable ciphers to use   
                              for SSL encryption                   
-ssl-key=file_namessl-key        The name of the SSL key file to use  
                              for establishing a secure            
                              connection                           
-ssl-verify-server-certssl-verify-server-certThe server's Common Name value in    
                              its certificate is verified          
                              against the hostname used when       
                              connecting to the server             
-table         table          Display output in tabular format     
-tee=file_name tee            Append a copy of output to the       
                              given file                           
-unbuffered    unbuffered     Flush the buffer after each query    
-user=user_nameuser           The MySQL username to use when       
                              connecting to the server             
-verbose                      Verbose mode                         
-version                      Display version information and exit 
-vertical      vertical       Print query output rows vertically   
                              (one line per column value)          
-wait          wait           If the connection cannot be          
                              established, wait and retry instead  
                              of  aborting                         
-xml           xml            Produce XML output                   

`mysql' supports the following options:

   *  `--help', `-?'

     Display a help message and exit.

   *  `--auto-rehash'

     Enable automatic rehashing. This option is on by default, which
     enables database, table, and column name completion.  Use
     `--disable-auto-rehash' to disable rehashing. That causes `mysql'
     to start faster, but you must issue the `rehash' command if you
     want to use name completion.

     To complete a name, enter the first part and press Tab. If the
     name is unambiguous, `mysql' completes it. Otherwise, you can
     press Tab again to see the possible names that begin with what you
     have typed so far. Completion does not occur if there is no
     default database.

   *  `--batch', `-B'

     Print results using tab as the column separator, with each row on
     a new line. With this option, `mysql' does not use the history
     file.

     Batch mode results in non-tabular output format and escaping of
     special characters. Escaping may be disabled by using raw mode;
     see the description for the `--raw' option.

   *  `--character-sets-dir=PATH'

     The directory where character sets are installed. See *Note
     charset-configuration::.

   *  `--column-names'

     Write column names in results.

   *  `--column-type-info', `-m'

     Display result set metadata. This option was added in MySQL
     5.1.14. (Before that, use `--debug-info'.)  The `-m' short option
     was added in MySQL 5.1.21.

   *  `--comments', `-c'

     Whether to preserve comments in statements sent to the server. The
     default is -skip-comments (discard comments), enable with
     -comments (preserve comments). This option was added in MySQL
     5.1.23.

   *  `--compress', `-C'

     Compress all information sent between the client and the server if
     both support compression.

   *  `--database=DB_NAME', `-D DB_NAME'

     The database to use. This is useful primarily in an option file.

   *  `--debug[=DEBUG_OPTIONS]', `-# [DEBUG_OPTIONS]'

     Write a debugging log. The DEBUG_OPTIONS string often is
     `'d:t:o,FILE_NAME''.  The default is `'d:t:o,/tmp/mysql.trace''.

   *  `--debug-check'

     Print some debugging information when the program exits.  This
     option was added in MySQL 5.1.21.

   *  `--debug-info', `-T'

     Before MySQL 5.1.14, this option prints debugging information and
     memory and CPU usage statistics when the program exits, and also
     causes display of result set metadata during execution. As of
     MySQL 5.1.14, use `--column-type-info' to display result set
     metadata.

   *  `--default-character-set=CHARSET_NAME'

     Use CHARSET_NAME as the default character set. See *Note
     charset-configuration::.

   *  `--delimiter=STR'

     Set the statement delimiter. The default is the semicolon
     character (``;'').

   *  `--disable-named-commands'

     Disable named commands. Use the `\*' form only, or use named
     commands only at the beginning of a line ending with a semicolon
     (``;'').  `mysql' starts with this option _enabled_ by default.
     However, even with this option, long-format commands still work
     from the first line. See *Note mysql-commands::.

   *  `--execute=STATEMENT', `-e STATEMENT'

     Execute the statement and quit. The default output format is like
     that produced with `--batch'. See *Note command-line-options::,
     for some examples.

   *  `--force', `-f'

     Continue even if an SQL error occurs.

   *  `--host=HOST_NAME', `-h HOST_NAME'

     Connect to the MySQL server on the given host.

   *  `--html', `-H'

     Produce HTML output.

   *  `--ignore-spaces', `-i'

     Ignore spaces after function names. The effect of this is
     described in the discussion for the `IGNORE_SPACE' SQL mode (see
     *Note server-sql-mode::).

   *  `--line-numbers'

     Write line numbers for errors. Disable this with
     `--skip-line-numbers'.

   *  `--local-infile[={0|1}]'

     Enable or disable `LOCAL' capability for `LOAD DATA INFILE'. With
     no value, the option enables `LOCAL'. The option may be given as
     `--local-infile=0' or `--local-infile=1' to explicitly disable or
     enable `LOCAL'. Enabling `LOCAL' has no effect if the server does
     not also support it.

     MySQL Enterprise

     For expert advice on the security implications of enabling
     `LOCAL', subscribe to the MySQL Enterprise Monitor. For more
     information, see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   *  `--named-commands', `-G'

     Enable named `mysql' commands. Long-format commands are allowed,
     not just short-format commands. For example, `quit' and `\q' both
     are recognized. Use `--skip-named-commands' to disable named
     commands. See *Note mysql-commands::.

   *  `--no-auto-rehash', `-A'

     Deprecated form of `-skip-auto-rehash'. Use
     `--disable-auto-rehash' instead. See the description for
     `--auto-rehash'.

   *  `--no-beep', `-b'

     Do not beep when errors occur.

   *  `--no-named-commands', `-g'

     Deprecated, use `--disable-named-commands' instead.

   *  `--no-pager'

     Deprecated form of `--skip-pager'. See the `--pager' option.

   *  `--no-tee'

     Do not copy output to a file.  *Note mysql-commands::, discusses
     tee files further.

   *  `--one-database', `-o'

     Ignore statements except those for the default database named on
     the command line. This is useful for skipping updates to other
     databases in the binary log.

   *  `--pager[=COMMAND]'

     Use the given command for paging query output. If the command is
     omitted, the default pager is the value of your `PAGER'
     environment variable. Valid pagers are `less', `more', `cat [>
     filename]', and so forth. This option works only on Unix. It does
     not work in batch mode.  To disable paging, use `--skip-pager'.
     *Note mysql-commands::, discusses output paging further.

   *  `--password[=PASSWORD]', `-p[PASSWORD]'

     The password to use when connecting to the server. If you use the
     short option form (`-p'), you _cannot_ have a space between the
     option and the password. If you omit the PASSWORD value following
     the `--password' or `-p' option on the command line, you are
     prompted for one.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security::.

   *  `--pipe', `-W'

     On Windows, connect to the server via a named pipe. This option
     applies only for connections to a local server, and only if the
     server supports named-pipe connections.

   *  `--port=PORT_NUM', `-P PORT_NUM'

     The TCP/IP port number to use for the connection.

   *  `--prompt=FORMAT_STR'

     Set the prompt to the specified format. The default is `mysql>'.
     The special sequences that the prompt can contain are described in
     *Note mysql-commands::.

   *  `--protocol={TCP|SOCKET|PIPE|MEMORY}'

     The connection protocol to use for connecting to the server.  It
     is useful when the other connection parameters normally would
     cause a protocol to be used other than the one you want. For
     details on the allowable values, see *Note connecting::.

   *  `--quick', `-q'

     Do not cache each query result, print each row as it is received.
     This may slow down the server if the output is suspended. With
     this option, `mysql' does not use the history file.

   *  `--raw', `-r'

     For tabular output, the `boxing' around columns enables one column
     value to be distinquished from another.  For non-tabular output
     (such as is produced in batch mode or when the `--batch' or
     `--silent' option is given), special characters are escaped in the
     output so they can be identified easily. Newline, tab, `NUL', and
     backslash are written as `\n', `\t', `\0', and `\\'. The `--raw'
     option disables this character escaping.

     The following example demonstrates tabular versus non-tabular
     output and the use of raw mode to disable escaping:

          % mysql
          mysql> SELECT CHAR(92);
          +----------+
          | CHAR(92) |
          +----------+
          | \        |
          +----------+

          % mysql -s
          mysql> SELECT CHAR(92);
          CHAR(92)
          \\

          % mysql -s -r
          mysql> SELECT CHAR(92);
          CHAR(92)
          \

   *  `--reconnect'

     If the connection to the server is lost, automatically try to
     reconnect. A single reconnect attempt is made each time the
     connection is lost. To suppress reconnection behavior, use
     `--skip-reconnect'.

   *  `--safe-updates', `--i-am-a-dummy', `-U'

     Allow only those `UPDATE' and `DELETE' statements that specify
     which rows to modify by using key values. If you have set this
     option in an option file, you can override it by using
     `--safe-updates' on the command line. See *Note mysql-tips::, for
     more information about this option.

   *  `--secure-auth'

     Do not send passwords to the server in old (pre-4.1.1) format.
     This prevents connections except for servers that use the newer
     password format.

     MySQL Enterprise

     For expert advice on database security, subscribe to the MySQL
     Enterprise Monitor. For more information, see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   *  `--show-warnings'

     Cause warnings to be shown after each statement if there are any.
     This option applies to interactive and batch mode.

   *  `--sigint-ignore'

     Ignore `SIGINT' signals (typically the result of typing Control-C).

   *  `--silent', `-s'

     Silent mode. Produce less output. This option can be given
     multiple times to produce less and less output.

     This option results in non-tabular output format and escaping of
     special characters. Escaping may be disabled by using raw mode;
     see the description for the `--raw' option.

   *  `--skip-column-names', `-N'

     Do not write column names in results. The short format, `-N' is
     deprecated, use the long format instead.

   *  `--skip-line-numbers', `-L'

     Do not write line numbers for errors. Useful when you want to
     compare result files that include error messages. The short
     format, `-L' is deprecated, use the long format instead.

   *  `--socket=PATH', `-S PATH'

     For connections to `localhost', the Unix socket file to use, or,
     on Windows, the name of the named pipe to use.

   *  `--ssl*'

     Options that begin with `--ssl' specify whether to connect to the
     server via SSL and indicate where to find SSL keys and
     certificates. See *Note ssl-options::.

   *  `--table', `-t'

     Display output in table format. This is the default for
     interactive use, but can be used to produce table output in batch
     mode.

   *  `--tee=FILE_NAME'

     Append a copy of output to the given file. This option does not
     work in batch mode. in *Note mysql-commands::, discusses tee files
     further.

   *  `--unbuffered', `-n'

     Flush the buffer after each query.

   *  `--user=USER_NAME', `-u USER_NAME'

     The MySQL username to use when connecting to the server.

   *  `--verbose', `-v'

     Verbose mode. Produce more output about what the program does.
     This option can be given multiple times to produce more and more
     output. (For example, `-v -v -v' produces table output format even
     in batch mode.)

   *  `--version', `-V'

     Display version information and exit.

   *  `--vertical', `-E'

     Print query output rows vertically (one line per column value).
     Without this option, you can specify vertical output for
     individual statements by terminating them with `\G'.

   *  `--wait', `-w'

     If the connection cannot be established, wait and retry instead of
     aborting.

   *  `--xml', `-X'

     Produce XML output.

     *Note*:

     Prior to MySQL 5.1.12, there was no differentiation in the output
     when using this option between columns containing the `NULL' value
     and columns containing the string literal `'NULL''; both were
     represented as

          <field name="COLUMN_NAME">NULL</field>

     Beginning with MySQL 5.1.12, the output when `--xml' is used with
     `mysql' matches that of `mysqldump `--xml''. See the section of the
     Manual which discusses the `--xml' option for `mysqldump' for
     details.

     Beginning with MySQL 5.1.18, the XML output also uses an XML
     namespace, as shown here:

          shell> mysql --xml -uroot -e "SHOW VARIABLES LIKE 'version%'"
          <?xml version="1.0"?>

          <resultset statement="SHOW VARIABLES LIKE 'version%'" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
          <row>
          <field name="Variable_name">version</field>
          <field name="Value">5.0.40-debug</field>
          </row>

          <row>
          <field name="Variable_name">version_comment</field>
          <field name="Value">Source distribution</field>
          </row>

          <row>
          <field name="Variable_name">version_compile_machine</field>
          <field name="Value">i686</field>
          </row>

          <row>
          <field name="Variable_name">version_compile_os</field>
          <field name="Value">suse-linux-gnu</field>
          </row>
          </resultset>

     (See Bug#25946 (http://bugs.mysql.com/25946).)

You can also set the following variables by using `--VAR_NAME=VALUE'.
The `--set-variable' format is deprecated.

   *  `connect_timeout'

     The number of seconds before connection timeout. (Default value is
     `0'.)

   *  `max_allowed_packet'

     The maximum packet length to send to or receive from the server.
     (Default value is 16MB.)

   *  `max_join_size'

     The automatic limit for rows in a join when using
     `--safe-updates'. (Default value is 1,000,000.)

   * `net_buffer_length'

     The buffer size for TCP/IP and socket communication.  (Default
     value is 16KB.)

   *  `select_limit'

     The automatic limit for `SELECT' statements when using
     `--safe-updates'. (Default value is 1,000.)

On Unix, the `mysql' client writes a record of executed statements to a
history file. By default, the history file is named `.mysql_history'
and is created in your home directory. To specify a different file, set
the value of the `MYSQL_HISTFILE' environment variable.

If you do not want to maintain a history file, first remove
`.mysql_history' if it exists, and then use either of the following
techniques:

   * Set the `MYSQL_HISTFILE' variable to `/dev/null'. To cause this
     setting to take effect each time you log in, put the setting in
     one of your shell's startup files.

   * Create `.mysql_history' as a symbolic link to `/dev/null':

          shell> ln -s /dev/null $HOME/.mysql_history

     You need do this only once.


File: manual.info,  Node: mysql-commands,  Next: mysql-server-side-help,  Prev: mysql-command-options,  Up: mysql

4.5.1.2 `mysql' Commands
........................

`mysql' sends each SQL statement that you issue to the server to be
executed. There is also a set of commands that `mysql' itself
interprets. For a list of these commands, type `help' or `\h' at the
`mysql>' prompt:

     mysql> help

     List of all MySQL commands:
     Note that all text commands must be first on line and end with ';'
     ?         (\?) Synonym for `help'.
     clear     (\c) Clear command.
     connect   (\r) Reconnect to the server. Optional arguments are db and host.
     delimiter (\d) Set statement delimiter. NOTE: Takes the rest of the line as
                    new delimiter.
     edit      (\e) Edit command with $EDITOR.
     ego       (\G) Send command to mysql server, display result vertically.
     exit      (\q) Exit mysql. Same as quit.
     go        (\g) Send command to mysql server.
     help      (\h) Display this help.
     nopager   (\n) Disable pager, print to stdout.
     notee     (\t) Don't write into outfile.
     pager     (\P) Set PAGER [to_pager]. Print the query results via PAGER.
     print     (\p) Print current command.
     prompt    (\R) Change your mysql prompt.
     quit      (\q) Quit mysql.
     rehash    (\#) Rebuild completion hash.
     source    (\.) Execute an SQL script file. Takes a file name as an argument.
     status    (\s) Get status information from the server.
     system    (\!) Execute a system shell command.
     tee       (\T) Set outfile [to_outfile]. Append everything into given
                    outfile.
     use       (\u) Use another database. Takes database name as argument.
     charset   (\C) Switch to another charset. Might be needed for processing
                    binlog with multi-byte charsets.
     warnings  (\W) Show warnings after every statement.
     nowarning (\w) Don't show warnings after every statement.

     For server side help, type 'help contents'

Each command has both a long and short form. The long form is not case
sensitive; the short form is. The long form can be followed by an
optional semicolon terminator, but the short form should not.

The use of short-form commands within multi-line `/* ...  */' comments
is not supported.

   * `help [ARG]', `\h [ARG]', `\? [ARG]', `? [ARG]'

     Displays a help message listing the available `mysql' commands.

     If you provide an argument to the `help' command, `mysql' uses it
     as a search string to access server-side help from the contents of
     the MySQL Reference Manual. For more information, see *Note
     mysql-server-side-help::.

   * `charset CHARSET_NAME', `\C CHARSET_NAME'

     The `charset' command changes the default character set and issues
     a `SET NAMES' statement. This enables the character set to remain
     synchronized on the client and server if `mysql' is run with
     auto-reconnect enabled (which is not recommended), because the
     specified character set is used for reconnects. This command was
     added in MySQL 5.1.7.

   * `clear', `\c'

     Clears the current input. Use this if you change your mind about
     executing the statement that you are entering.

   * `connect [DB_NAME HOST_NAME]]', `\r [DB_NAME HOST_NAME]]'

     Reconnects to the server. The optional database name and hostname
     arguments may be given to specify the default database or the host
     where the server is running. If omitted, the current values are
     used.

   * `delimiter STR', `\d STR'

     The `delimiter' command changes the string that `mysql' interprets
     as the separator between SQL statements. The default is the
     semicolon character (``;''). You should avoid the use of the
     backslash (``\'') character within the delimiter because that is
     the escape character for MySQL.

     When the delimiter recognized by `mysql' is set to something other
     than the default of ``;'', instances of that character are sent to
     the server without interpretation.  However, the server itself
     still interprets ``;'' as a statement delimiter and processes
     statements accordingly. This behavior on the server side comes
     into play for multiple-statement execution (see *Note
     c-api-multiple-queries::), and for parsing the body of stored
     procedures and functions, triggers, and events (see *Note
     create-procedure::).

   * `edit', `\e'

     Edits the current input statement. `mysql' checks the values of
     the `EDITOR' and `VISUAL' environment variables to determine which
     editor to use. The default editor is `vi' if neither variable is
     set.

     The `edit' command works only in Unix.

   * `ego', `\G'

     Sends the current statement to the server to be executed and
     displays the result using vertical format.

   * `exit', `\q'

     Exits `mysql'.

   * `go', `\g'

     Sends the current statement to the server to be executed.

   * `nopager', `\n'

     Disables output paging. See the description for `pager'.

     The `nopager' command works only in Unix.

   * `notee', `\t'

     Disables output copying to the tee file. See the description for
     `tee'.

   * `nowarning', `\w'

     Enables display of warnings after each statement.

   * `pager [COMMAND]', `\P [COMMAND]'

     By using the `--pager' option when you invoke `mysql', it is
     possible to browse or search query results in interactive mode
     with Unix programs such as `less', `more', or any other similar
     program. If you specify no value for the option, `mysql' checks
     the value of the `PAGER' environment variable and sets the pager
     to that.

     Output paging can be enabled interactively with the `pager'
     command and disabled with `nopager'. The command takes an optional
     argument; if given, the paging program is set to that. With no
     argument, the pager is set to the pager that was set on the
     command line, or `stdout' if no pager was specified.

     Output paging works only in Unix because it uses the `popen()'
     function, which does not exist on Windows. For Windows, the `tee'
     option can be used instead to save query output, although it is
     not as convenient as `pager' for browsing output in some
     situations.

   * `print', `\p'

     Prints the current input statement without executing it.

   * `prompt [STR]', `\R [STR]'

     Reconfigures the `mysql' prompt to the given string. The special
     character sequences that can be used in the prompt are described
     later in this section.

     If you specify the `prompt' command with no argument, `mysql'
     resets the prompt to the default of `mysql>'.

   * `quit', `\q'

     Exits `mysql'.

   * `rehash', `\#'

     Rebuilds the completion hash that enables database, table, and
     column name completion while you are entering statements. (See the
     description for the `--auto-rehash' option.)

   * `source FILE_NAME', `\.  FILE_NAME'

     Reads the named file and executes the statements contained
     therein. On Windows, you can specify pathname separators as `/' or
     `\\'.

   * `status', `\s'

     The `status' command provides some information about the
     connection and the server you are using. If you are running in
     `--safe-updates' mode, `status' also prints the values for the
     `mysql' variables that affect your queries.

   * `system COMMAND', `\!  COMMAND'

     Executes the given command using your default command interpreter.

     The `system' command works only in Unix.

   * `tee [FILE_NAME]', `\T [FILE_NAME]'

     By using the `--tee' option when you invoke `mysql', you can log
     statements and their output. All the data displayed on the screen
     is appended into a given file. This can be very useful for
     debugging purposes also. `mysql' flushes results to the file after
     each statement, just before it prints its next prompt.

     You can enable this feature interactively with the `tee' command.
     Without a parameter, the previous file is used. The `tee' file can
     be disabled with the `notee' command.  Executing `tee' again
     re-enables logging.

   * `use DB_NAME', `\u DB_NAME'

     Uses DB_NAME as the default database.

   * `warnings', `\W'

     Enables display of warnings after each statement (if there are
     any).

Here are a few tips about the `pager' command:

   * You can use it to write to a file and the results go only to the
     file:

          mysql> pager cat > /tmp/log.txt

     You can also pass any options for the program that you want to use
     as your pager:

          mysql> pager less -n -i -S

   * In the preceding example, note the `-S' option. You may find it
     very useful for browsing wide query results. Sometimes a very wide
     result set is difficult to read on the screen. The `-S' option to
     `less' can make the result set much more readable because you can
     scroll it horizontally using the left-arrow and right-arrow keys.
     You can also use `-S' interactively within `less' to switch the
     horizontal-browse mode on and off. For more information, read the
     `less' manual page:

          shell> man less

   * The `-F' and `-X' options may be used with `less' to cause it to
     exit if output fits on one screen, which is convenient when no
     scrolling is necessary:

          mysql> pager less -n -i -S -F -X

   * You can specify very complex pager commands for handling query
     output:

          mysql> pager cat | tee /dr1/tmp/res.txt \
                    | tee /dr2/tmp/res2.txt | less -n -i -S

     In this example, the command would send query results to two files
     in two different directories on two different filesystems mounted
     on `/dr1' and `/dr2', yet still display the results onscreen via
     `less'.

You can also combine the `tee' and `pager' functions. Have a `tee' file
enabled and `pager' set to `less', and you are able to browse the
results using the `less' program and still have everything appended
into a file the same time. The difference between the Unix `tee' used
with the `pager' command and the `mysql' built-in `tee' command is that
the built-in `tee' works even if you do not have the Unix `tee'
available. The built-in `tee' also logs everything that is printed on
the screen, whereas the Unix `tee' used with `pager' does not log quite
that much.  Additionally, `tee' file logging can be turned on and off
interactively from within `mysql'.  This is useful when you want to log
some queries to a file, but not others.

The `prompt' command reconfigures the default `mysql>' prompt. The
string for defining the prompt can contain the following special
sequences:

*Option*    *Description*
`\c'        A counter that increments for each statement you issue
`\D'        The full current date
`\d'        The default database
`\h'        The server host
`\l'        The current delimiter (new in 5.1.12)
`\m'        Minutes of the current time
`\n'        A newline character
`\O'        The current month in three-letter format (Jan, Feb,
            ...)
`\o'        The current month in numeric format
`\P'        am/pm
`\p'        The current TCP/IP port or socket file
`\R'        The current time, in 24-hour military time (0-23)
`\r'        The current time, standard 12-hour time (1-12)
`\S'        Semicolon
`\s'        Seconds of the current time
`\t'        A tab character
`\U'        Your full `USER_NAME@HOST_NAME' account name
`\u'        Your username
`\v'        The server version
`\w'        The current day of the week in three-letter format
            (Mon, Tue, ...)
`\Y'        The current year, four digits
`\y'        The current year, two digits
`\_'        A space
`\ '        A space (a space follows the backslash)
`\''        Single quote
`\"'        Double quote
`\\'        A literal ``\'' backslash character
`\X'        X, for any `X' not listed above

You can set the prompt in several ways:

   * _Use an environment variable._ You can set the `MYSQL_PS1'
     environment variable to a prompt string. For example:

          shell> export MYSQL_PS1="(\u@\h) [\d]> "

   * _Use a command-line option._ You can set the `--prompt' option on
     the command line to `mysql'. For example:

          shell> mysql --prompt="(\u@\h) [\d]> "
          (user@host) [database]>

   * _Use an option file._ You can set the `prompt' option in the
     `[mysql]' group of any MySQL option file, such as `/etc/my.cnf' or
     the `.my.cnf' file in your home directory.  For example:

          [mysql]
          prompt=(\\u@\\h) [\\d]>\\_

     In this example, note that the backslashes are doubled. If you set
     the prompt using the `prompt' option in an option file, it is
     advisable to double the backslashes when using the special prompt
     options. There is some overlap in the set of allowable prompt
     options and the set of special escape sequences that are
     recognized in option files. (These sequences are listed in *Note
     option-files::.) The overlap may cause you problems if you use
     single backslashes. For example, `\s' is interpreted as a space
     rather than as the current seconds value. The following example
     shows how to define a prompt within an option file to include the
     current time in `HH:MM:SS>' format:

          [mysql]
          prompt="\\r:\\m:\\s> "

   * _Set the prompt interactively._ You can change your prompt
     interactively by using the `prompt' (or `\R') command. For example:

          mysql> prompt (\u@\h) [\d]>\_
          PROMPT set to '(\u@\h) [\d]>\_'
          (USER@HOST) [DATABASE]>
          (USER@HOST) [DATABASE]> prompt
          Returning to default PROMPT of mysql>
          mysql>

   *

File: manual.info,  Node: mysql-server-side-help,  Next: batch-commands,  Prev: mysql-commands,  Up: mysql

4.5.1.3 `mysql' Server-Side Help
................................

     mysql> help SEARCH_STRING

If you provide an argument to the `help' command, `mysql' uses it as a
search string to access server-side help from the contents of the MySQL
Reference Manual. The proper operation of this command requires that the
help tables in the `mysql' database be initialized with help topic
information (see *Note server-side-help-support::).

If there is no match for the search string, the search fails:

     mysql> help me

     Nothing found
     Please try to run 'help contents' for a list of all accessible topics

Use `help contents' to see a list of the help categories:

     mysql> help contents
     You asked for help about help category: "Contents"
     For more information, type 'help <item>', where <item> is one of the
     following categories:
        Account Management
        Administration
        Data Definition
        Data Manipulation
        Data Types
        Functions
        Functions and Modifiers for Use with GROUP BY
        Geographic Features
        Language Structure
        Plugins
        Storage Engines
        Stored Routines
        Table Maintenance
        Transactions
        Triggers

If the search string matches multiple items, `mysql' shows a list of
matching topics:

     mysql> help logs
     Many help items for your request exist.
     To make a more specific request, please type 'help <item>',
     where <item> is one of the following topics:
        SHOW
        SHOW BINARY LOGS
        SHOW ENGINE
        SHOW LOGS

Use a topic as the search string to see the help entry for that topic:

     mysql> help show binary logs
     Name: 'SHOW BINARY LOGS'
     Description:
     Syntax:
     SHOW BINARY LOGS
     SHOW MASTER LOGS

     Lists the binary log files on the server. This statement is used as
     part of the procedure described in [purge-master-logs], that shows how
     to determine which logs can be purged.

     mysql> SHOW BINARY LOGS;
     +---------------+-----------+
     | Log_name      | File_size |
     +---------------+-----------+
     | binlog.000015 |    724935 |
     | binlog.000016 |    733481 |
     +---------------+-----------+


File: manual.info,  Node: batch-commands,  Next: mysql-tips,  Prev: mysql-server-side-help,  Up: mysql

4.5.1.4 Executing SQL Statements from a Text File
.................................................

The `mysql' client typically is used interactively, like this:

     shell> mysql DB_NAME

However, it is also possible to put your SQL statements in a file and
then tell `mysql' to read its input from that file. To do so, create a
text file TEXT_FILE that contains the statements you wish to execute.
Then invoke `mysql' as shown here:

     shell> mysql DB_NAME < TEXT_FILE

If you place a `USE DB_NAME' statement as the first statement in the
file, it is unnecessary to specify the database name on the command
line:

     shell> mysql < text_file

If you are already running `mysql', you can execute an SQL script file
using the `source' command or `\.' command:

     mysql> source FILE_NAME
     mysql> \. FILE_NAME

Sometimes you may want your script to display progress information to
the user. For this you can insert statements like this:

     SELECT '<info_to_display>' AS ' ';

The statement shown outputs `<info_to_display>'.

As of MySQL 5.1.23, `mysql' ignores Unicode byte order mark (BOM)
characters at the beginning of input files. Previously, it read them
and sent them to the server, resulting in a syntax error. Presence of a
BOM does not cause `mysql' to change its default character set. To do
that, invoke `mysql' with an option such as
`--default-character-set=utf8'.

For more information about batch mode, see *Note batch-mode::.


File: manual.info,  Node: mysql-tips,  Prev: batch-commands,  Up: mysql

4.5.1.5 `mysql' Tips
....................

* Menu:

* vertical-query-results::       Displaying Query Results Vertically
* safe-updates::                 Using the `--safe-updates' Option
* mysql-reconnect::              Disabling `mysql' Auto-Reconnect

This section describes some techniques that can help you use `mysql'
more effectively.


File: manual.info,  Node: vertical-query-results,  Next: safe-updates,  Prev: mysql-tips,  Up: mysql-tips

4.5.1.6 Displaying Query Results Vertically
...........................................

Some query results are much more readable when displayed vertically,
instead of in the usual horizontal table format.  Queries can be
displayed vertically by terminating the query with \G instead of a
semicolon. For example, longer text values that include newlines often
are much easier to read with vertical output:

     mysql> SELECT * FROM mails WHERE LENGTH(txt) < 300 LIMIT 300,1\G
     *************************** 1. row ***************************
       msg_nro: 3068
          date: 2000-03-01 23:29:50
     time_zone: +0200
     mail_from: Monty
         reply: monty@no.spam.com
       mail_to: "Thimble Smith" <tim@no.spam.com>
           sbj: UTF-8
           txt: >>>>> "Thimble" == Thimble Smith writes:

     Thimble> Hi.  I think this is a good idea.  Is anyone familiar
     Thimble> with UTF-8 or Unicode? Otherwise, I'll put this on my
     Thimble> TODO list and see what happens.

     Yes, please do that.

     Regards,
     Monty
          file: inbox-jani-1
          hash: 190402944
     1 row in set (0.09 sec)


File: manual.info,  Node: safe-updates,  Next: mysql-reconnect,  Prev: vertical-query-results,  Up: mysql-tips

4.5.1.7 Using the `--safe-updates' Option
.........................................

For beginners, a useful startup option is `--safe-updates' (or
`--i-am-a-dummy', which has the same effect).  It is helpful for cases
when you might have issued a `DELETE FROM TBL_NAME' statement but
forgotten the `WHERE' clause. Normally, such a statement deletes all
rows from the table. With `--safe-updates', you can delete rows only by
specifying the key values that identify them. This helps prevent
accidents.

When you use the `--safe-updates' option, `mysql' issues the following
statement when it connects to the MySQL server:

     SET SQL_SAFE_UPDATES=1,SQL_SELECT_LIMIT=1000, SQL_MAX_JOIN_SIZE=1000000;

See *Note server-session-variables::.

The `SET' statement has the following effects:

   * You are not allowed to execute an `UPDATE' or `DELETE' statement
     unless you specify a key constraint in the `WHERE' clause or
     provide a `LIMIT' clause (or both). For example:

          UPDATE TBL_NAME SET NOT_KEY_COLUMN=VAL WHERE KEY_COLUMN=VAL;

          UPDATE TBL_NAME SET NOT_KEY_COLUMN=VAL LIMIT 1;

   * The server limits all large `SELECT' results to 1,000 rows unless
     the statement includes a `LIMIT' clause.

   * The server aborts multiple-table `SELECT' statements that probably
     need to examine more than 1,000,000 row combinations.

To specify limits different from 1,000 and 1,000,000, you can override
the defaults by using the `--select_limit' and `--max_join_size'
options:

     shell> mysql --safe-updates --select_limit=500 --max_join_size=10000


File: manual.info,  Node: mysql-reconnect,  Prev: safe-updates,  Up: mysql-tips

4.5.1.8 Disabling `mysql' Auto-Reconnect
........................................

If the `mysql' client loses its connection to the server while sending
a statement, it immediately and automatically tries to reconnect once
to the server and send the statement again. However, even if `mysql'
succeeds in reconnecting, your first connection has ended and all your
previous session objects and settings are lost: temporary tables, the
autocommit mode, and user-defined and session variables. Also, any
current transaction rolls back.  This behavior may be dangerous for
you, as in the following example where the server was shut down and
restarted between the first and second statements without you knowing
it:

     mysql> SET @a=1;
     Query OK, 0 rows affected (0.05 sec)

     mysql> INSERT INTO t VALUES(@a);
     ERROR 2006: MySQL server has gone away
     No connection. Trying to reconnect...
     Connection id:    1
     Current database: test

     Query OK, 1 row affected (1.30 sec)

     mysql> SELECT * FROM t;
     +------+
     | a    |
     +------+
     | NULL |
     +------+
     1 row in set (0.05 sec)

The `@a' user variable has been lost with the connection, and after the
reconnection it is undefined. If it is important to have `mysql'
terminate with an error if the connection has been lost, you can start
the `mysql' client with the `--skip-reconnect' option.

For more information about auto-reconnect and its effect on state
information when a reconnection occurs, see *Note auto-reconnect::.


File: manual.info,  Node: mysqladmin,  Next: mysqlcheck,  Prev: mysql,  Up: programs-client

4.5.2 `mysqladmin' -- Client for Administering a MySQL Server
-------------------------------------------------------------

`mysqladmin' is a client for performing administrative operations. You
can use it to check the server's configuration and current status, to
create and drop databases, and more.

Invoke `mysqladmin' like this:

     shell> mysqladmin [OPTIONS] COMMAND [COMMAND-ARG] [COMMAND [COMMAND-ARG]] ...

`mysqladmin' supports the commands described in the following list.
Some of the commands take an argument following the command name.

   *  `create DB_NAME'

     Create a new database named DB_NAME.

   *  `debug'

     Tell the server to write debug information to the error log.

     Beginning with MySQL 5.1.12, this includes information about the
     Event Scheduler. See *Note events-status-info::.

   *  `--debug-check'

     Print some debugging information when the program exits.  This
     option was added in MySQL 5.1.21.

   *  `--debug-info'

     Print debugging information and memory and CPU usage statistics
     when the program exits. This option was added in MySQL 5.1.14.

   *  `drop DB_NAME'

     Delete the database named DB_NAME and all its tables.

   *  `extended-status'

     Display the server status variables and their values.

     MySQL Enterprise

     For expert advice on using server status variables, subscribe to
     the MySQL Enterprise Monitor. For more information see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   *  `flush-hosts'

     Flush all information in the host cache.

   *  `flush-logs'

     Flush all logs.

   *  `flush-privileges'

     Reload the grant tables (same as `reload').

   *  `flush-status'

     Clear status variables.

   *  `flush-tables'

     Flush all tables.

   *  `flush-threads'

     Flush the thread cache.

   *  `kill ID,ID,...'

     Kill server threads. If multiple thread ID values are given, there
     must be no spaces in the list.

   *  `old-password NEW-PASSWORD'

     This is like the `password' command but stores the password using
     the old (pre-4.1) password-hashing format. (See *Note
     password-hashing::.)

     MySQL Enterprise

     For expert advice on the security implications of using the
     `old-password' command, subscribe to the MySQL Enterprise Monitor.
     For more information, see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   *  `password NEW-PASSWORD'

     Set a new password. This changes the password to NEW-PASSWORD for
     the account that you use with `mysqladmin' for connecting to the
     server. Thus, the next time you invoke `mysqladmin' (or any other
     client program) using the same account, you will need to specify
     the new password.

     If the NEW-PASSWORD value contains spaces or other characters that
     are special to your command interpreter, you need to enclose it
     within quotes.  On Windows, be sure to use double quotes rather
     than single quotes; single quotes are not stripped from the
     password, but rather are interpreted as part of the password. For
     example:

          shell> mysqladmin password "my new password"

   *  `ping'

     Check whether the server is alive. The return status from
     `mysqladmin' is 0 if the server is running, 1 if it is not. This
     is 0 even in case of an error such as `Access denied', because
     this means that the server is running but refused the connection,
     which is different from the server not running.

   *  `processlist'

     Show a list of active server threads. This is like the output of
     the `SHOW PROCESSLIST' statement.  If the `--verbose' option is
     given, the output is like that of `SHOW FULL PROCESSLIST'. (See
     *Note show-processlist::.)

   *  `reload'

     Reload the grant tables.

   *  `refresh'

     Flush all tables and close and open log files.

   *  `shutdown'

     Stop the server.

   *  `start-slave'

     Start replication on a slave server.

   *  `status'

     Display a short server status message.

   *  `stop-slave'

     Stop replication on a slave server.

   *  `variables'

     Display the server system variables and their values.

     MySQL Enterprise

     For expert advice on using server system variables, subscribe to
     the MySQL Enterprise Monitor. For more information see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   *  `version'

     Display version information from the server.

All commands can be shortened to any unique prefix. For example:

     shell> mysqladmin proc stat
     +----+-------+-----------+----+---------+------+-------+------------------+
     | Id | User  | Host      | db | Command | Time | State | Info             |
     +----+-------+-----------+----+---------+------+-------+------------------+
     | 51 | monty | localhost |    | Query   | 0    |       | show processlist |
     +----+-------+-----------+----+---------+------+-------+------------------+
     Uptime: 1473624  Threads: 1  Questions: 39487
     Slow queries: 0  Opens: 541  Flush tables: 1
     Open tables: 19  Queries per second avg: 0.0268

The `mysqladmin status' command result displays the following values:

   * `Uptime'

     The number of seconds the MySQL server has been running.

   * `Threads'

     The number of active threads (clients).

   * `Questions'

     The number of questions (queries) from clients since the server
     was started.

   * `Slow queries'

     The number of queries that have taken more than `long_query_time'
     seconds. See *Note slow-query-log::.

   * `Opens'

     The number of tables the server has opened.

   * `Flush tables'

     The number of `flush-*', `refresh', and `reload' commands the
     server has executed.

   * `Open tables'

     The number of tables that currently are open.

   * `Memory in use'

     The amount of memory allocated directly by `mysqld'. This value is
     displayed only when MySQL has been compiled with
     `--with-debug=full'.

   * `Maximum memory used'

     The maximum amount of memory allocated directly by `mysqld'. This
     value is displayed only when MySQL has been compiled with
     `--with-debug=full'.

If you execute `mysqladmin shutdown' when connecting to a local server
using a Unix socket file, `mysqladmin' waits until the server's process
ID file has been removed, to ensure that the server has stopped
properly.

*`mysqladmin' Option Reference*

*Format*       *Config File*  *Description*                        *Introduction*
-compress      compress       Compress all information sent        
                              between the client and the server    
-connect_timeout=secondsconnect_timeoutThe number of seconds before         
                              connection timeout                   
-count=#       count          The number of iterations to make     
                              for repeated command execution       
-debug[=debug_options]debug          Write a debugging log                
-debug-check   debug-check    Print debugging information when     5.1.21
                              the program exits                    
-debug-info    debug-info     Print debugging information, memory  5.1.14
                              and CPU statistics when the          
                              program exits                        
-default-character-set=charset_namedefault-character-setUse charset_name as the default      
                              character set                        
-force         force          Continue even if an SQL error occurs 
-help                         Display help message and exit        
-host=host_namehost           Connect to the MySQL server on the   
                              given host                           
-no-beep       no-beep        Do not beep when errors occur        5.1.17
-password[=password]password       The password to use when connecting  
                              to the server                        
-pipe                         On Windows, connect to server via a  
                              named pipe                           
-port=port_num port           The TCP/IP port number to use for    
                              the connection                       
-protocol=type protocol       The connection protocol to use       
-relative      relative       Show the difference between the      
                              current and previous values when     
                              used with the -sleep option          
-shutdown_timeout=secondsshutdown_timeoutThe maximum number of seconds to     
                              wait for server shutdown             
-silent        silent         Silent mode                          
-sleep=delay   sleep          Execute commands repeatedly,         
                              sleeping for delay seconds in        
                              between                              
-socket=path   socket         For connections to localhost         
-ssl-ca=file_namessl-ca         The path to a file that contains a   
                              list of trusted SSL CAs              
-ssl-capath=directory_namessl-capath     The path to a directory that         
                              contains trusted SSL CA              
                              certificates  in PEM format          
-ssl-cert=file_namessl-cert       The name of the SSL certificate      
                              file to use for establishing a       
                              secure connection                    
-ssl-cipher=cipher_listssl-cipher     A list of allowable ciphers to use   
                              for SSL encryption                   
-ssl-key=file_namessl-key        The name of the SSL key file to use  
                              for establishing a secure            
                              connection                           
-ssl-verify-server-certssl-verify-server-certThe server's Common Name value in    
                              its certificate is verified          
                              against the hostname used when       
                              connecting to the server             
-user=user_name,user           The MySQL username to use when       
                              connecting to the server             
-verbose                      Verbose mode                         
-version                      Display version information and exit 
-vertical      vertical       Print query output rows vertically   
                              (one line per column value)          
-wait          wait           If the connection cannot be          
                              established, wait and retry instead  
                              of  aborting                         

`mysqladmin' supports the following options:

   *  `--help', `-?'

     Display a help message and exit.

   *  `--character-sets-dir=PATH'

     The directory where character sets are installed. See *Note
     charset-configuration::.

   *  `--compress', `-C'

     Compress all information sent between the client and the server if
     both support compression.

   *  `--count=N', `-c N'

     The number of iterations to make for repeated command execution if
     the `--sleep' option is given.

   *  `--debug[=DEBUG_OPTIONS]', `-# [DEBUG_OPTIONS]'

     Write a debugging log. The DEBUG_OPTIONS string often is
     `'d:t:o,FILE_NAME''.  The default is
     `'d:t:o,/tmp/mysqladmin.trace''.

   *  `--default-character-set=CHARSET_NAME'

     Use CHARSET_NAME as the default character set. See *Note
     charset-configuration::.

   *  `--force', `-f'

     Do not ask for confirmation for the `drop DB_NAME' command. With
     multiple commands, continue even if an error occurs.

   *  `--host=HOST_NAME', `-h HOST_NAME'

     Connect to the MySQL server on the given host.

   *  `--no-beep', `-b'

     Suppress the warning beep that is emitted by default for errors
     such as a failure to connect to the server. This option was added
     in MySQL 5.1.17.

   *  `--password[=PASSWORD]', `-p[PASSWORD]'

     The password to use when connecting to the server. If you use the
     short option form (`-p'), you _cannot_ have a space between the
     option and the password. If you omit the PASSWORD value following
     the `--password' or `-p' option on the command line, you are
     prompted for one.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security::.

   *  `--pipe', `-W'

     On Windows, connect to the server via a named pipe. This option
     applies only for connections to a local server, and only if the
     server supports named-pipe connections.

   *  `--port=PORT_NUM', `-P PORT_NUM'

     The TCP/IP port number to use for the connection.

   *  `--protocol={TCP|SOCKET|PIPE|MEMORY}'

     The connection protocol to use for connecting to the server.  It
     is useful when the other connection parameters normally would
     cause a protocol to be used other than the one you want. For
     details on the allowable values, see *Note connecting::.

   *  `--relative', `-r'

     Show the difference between the current and previous values when
     used with the `--sleep' option.  Currently, this option works only
     with the `extended-status' command.

   *  `--silent', `-s'

     Exit silently if a connection to the server cannot be established.

   *  `--sleep=DELAY', `-i DELAY'

     Execute commands repeatedly, sleeping for DELAY seconds in
     between. The `--count' option determines the number of iterations.
     If `--count' is not given, `mysqladmin' executes commands
     indefinitely until interrupted.

   *  `--socket=PATH', `-S PATH'

     For connections to `localhost', the Unix socket file to use, or,
     on Windows, the name of the named pipe to use.

   *  `--ssl*'

     Options that begin with `--ssl' specify whether to connect to the
     server via SSL and indicate where to find SSL keys and
     certificates. See *Note ssl-options::.

   *  `--user=USER_NAME', `-u USER_NAME'

     The MySQL username to use when connecting to the server.

   *  `--verbose', `-v'

     Verbose mode. Print more information about what the program does.

   *  `--version', `-V'

     Display version information and exit.

   *  `--vertical', `-E'

     Print output vertically. This is similar to `--relative', but
     prints output vertically.

   *  `--wait[=COUNT]', `-w[COUNT]'

     If the connection cannot be established, wait and retry instead of
     aborting. If a COUNT value is given, it indicates the number of
     times to retry.  The default is one time.

You can also set the following variables by using `--VAR_NAME=VALUE'
The `--set-variable' format is deprecated.  syntax:

   *  `connect_timeout'

     The maximum number of seconds before connection timeout. The
     default value is 43200 (12 hours).

   *  `shutdown_timeout'

     The maximum number of seconds to wait for server shutdown.  The
     default value is 3600 (1 hour).


File: manual.info,  Node: mysqlcheck,  Next: mysqldump,  Prev: mysqladmin,  Up: programs-client

4.5.3 `mysqlcheck' -- A Table Maintenance and Repair Program
------------------------------------------------------------

The `mysqlcheck' client checks, repairs, optimizes, and analyzes tables.

`mysqlcheck' is similar in function to `myisamchk', but works
differently. The main operational difference is that `mysqlcheck' must
be used when the `mysqld' server is running, whereas `myisamchk' should
be used when it is not. The benefit of using `mysqlcheck' is that you
do not have to stop the server to check or repair your tables.

`mysqlcheck' uses the SQL statements `CHECK TABLE', `REPAIR TABLE',
`ANALYZE TABLE', and `OPTIMIZE TABLE' in a convenient way for the user.
It determines which statements to use for the operation you want to
perform, and then sends the statements to the server to be executed. For
details about which storage engines each statement works with, see the
descriptions for those statements in *Note sql-syntax::.

The `MyISAM' storage engine supports all four statements, so
`mysqlcheck' can be used to perform all four operations on `MyISAM'
tables.  Other storage engines do not necessarily support all
operations.  In such cases, an error message is displayed. For example,
if `test.t' is a `MEMORY' table, an attempt to check it produces this
result:

     shell> mysqlcheck test t
     test.t
     note     : The storage engine for the table doesn't support check

The use of `mysqlcheck' with partitioned tables is not supported.

*Caution*:

It is best to make a backup of a table before performing a table repair
operation; under some circumstances the operation might cause data
loss. Possible causes include but are not limited to filesystem errors.

There are three general ways to invoke `mysqlcheck':

     shell> mysqlcheck [OPTIONS] DB_NAME [TABLES]
     shell> mysqlcheck [OPTIONS] --databases DB_NAME1 [DB_NAME2 DB_NAME3...]
     shell> mysqlcheck [OPTIONS] --all-databases

If you do not name any tables following DB_NAME or if you use the
`--databases' or `--all-databases' option, entire databases are checked.

`mysqlcheck' has a special feature compared to other client programs.
The default behavior of checking tables (`--check') can be changed by
renaming the binary. If you want to have a tool that repairs tables by
default, you should just make a copy of `mysqlcheck' named
`mysqlrepair', or make a symbolic link to `mysqlcheck' named
`mysqlrepair'. If you invoke `mysqlrepair', it repairs tables.

The following names can be used to change `mysqlcheck' default behavior:

`mysqlrepair'      The default option is `--repair'
`mysqlanalyze'     The default option is `--analyze'
`mysqloptimize'    The default option is `--optimize'

*`mysqlcheck' Option Reference*

*Format*       *Config File*  *Description*                        *Introduction*
-all-databases all-databases  Check all tables in all databases    
-all-in-1      all-in-1       Execute a single statement for each  
                              database that names all the  tables  
                              from that database                   
-analyze       analyze        Analyze the tables                   
-auto-repair   auto-repair    If a checked table is corrupted,     
                              automatically fix it                 
-bind-address=host_name               Determine which client network       5.1.22-ndb-6.3.4
                              interface (IP address or hostname)   
                              to use when connecting to the MySQL  
                              Server                               
-character-sets-dir=pathcharacter-sets-dirThe directory where character sets   
                              are installed                        
-check         check          Check the tables for errors          
-check-only-changedcheck-only-changedCheck only tables that have changed  
                              since the last check                 
-check-upgrade check-upgrade  Invoke CHECK TABLE with the FOR      5.1.7
                              UPGRADE option                       
-compress      compress       Compress all information sent        
                              between the client and the server    
-databases     databases      Process all tables in the named      
                              databases                            
-debug[=debug_options]debug          Write a debugging log                
-debug-check   debug-check    Print debugging information when     5.1.21
                              the program exits                    
-debug-info    debug-info     Print debugging information, memory  5.1.14
                              and CPU statistics when the          
                              program exits                        
-default-character-set=charset_namedefault-character-setUse charset_name as the default      
                              character set                        
-extended      extended       Check and repair tables              
-fast          fast           Check only tables that have not      
                              been closed properly                 
-fix-db-names  fix-db-names   Convert database names to 5.1 format 5.1.7
-fix-table-namesfix-table-namesConvert table names to 5.1 format    5.1.7
-force         force          Continue even if an SQL error occurs 
-help                         Display help message and exit        
-host=host_namehost           Connect to the MySQL server on the   
                              given host                           
-medium-check  medium-check   Do a check that is faster than an    
                              -extended operation                  
-optimize      optimize       Optimize the tables                  
-password[=password]password       The password to use when connecting  
                              to the server                        
-pipe                         On Windows, connect to server via a  
                              named pipe                           
-port=port_num port           The TCP/IP port number to use for    
                              the connection                       
-protocol=type protocol       The connection protocol to use       
-quick         quick          The fastest method of checking       
-repair        repair         Perform a repair that can fix        
                              almost anything except unique keys   
                              that are not unique                  
-silent        silent         Silent mode                          
-socket=path   socket         For connections to localhost         
-ssl-ca=file_namessl-ca         The path to a file that contains a   
                              list of trusted SSL CAs              
-ssl-capath=directory_namessl-capath     The path to a directory that         
                              contains trusted SSL CA              
                              certificates  in PEM format          
-ssl-cert=file_namessl-cert       The name of the SSL certificate      
                              file to use for establishing a       
                              secure connection                    
-ssl-cipher=cipher_listssl-cipher     A list of allowable ciphers to use   
                              for SSL encryption                   
-ssl-key=file_namessl-key        The name of the SSL key file to use  
                              for establishing a secure            
                              connection                           
-ssl-verify-server-certssl-verify-server-certThe server's Common Name value in    
                              its certificate is verified          
                              against the hostname used when       
                              connecting to the server             
-tables        tables         Overrides the -databases or -B       
                              option                               
-use-frm       use-frm        For repair operations on MyISAM      
                              tables                               
-user=user_name,user           The MySQL username to use when       
                              connecting to the server             
-verbose                      Verbose mode                         
-version                      Display version information and exit 
-write-binlog  write-binlog   Log ANALYZE, OPTIMIZE, REPAIR        5.1.18
                              statements to binary log.            
                              -skip-write-binlog adds              
                              NO_WRITE_TO_BINLOG to these          
                              statements.                          

`mysqlcheck' supports the following options:

   *  `--help', `-?'

     Display a help message and exit.

   *  `--all-databases', `-A'

     Check all tables in all databases. This is the same as using the
     `--databases' option and naming all the databases on the command
     line.

   *  `--all-in-1', `-1'

     Instead of issuing a statement for each table, execute a single
     statement for each database that names all the tables from that
     database to be processed.

   *  `--analyze', `-a'

     Analyze the tables.

     MySQL Enterprise

     For expert advice on optimizing tables, subscribe to the MySQL
     Enterprise Monitor. For more information, see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   *  `--auto-repair'

     If a checked table is corrupted, automatically fix it. Any
     necessary repairs are done after all tables have been checked.

   *  `--character-sets-dir=PATH'

     The directory where character sets are installed. See *Note
     charset-configuration::.

   *  `--check', `-c'

     Check the tables for errors. This is the default operation.

   *  `--check-only-changed', `-C'

     Check only tables that have changed since the last check or that
     have not been closed properly.

   *  `--check-upgrade', `-g'

     Invoke `CHECK TABLE' with the `FOR UPGRADE' option to check tables
     for incompatibilities with the current version of the server.
     This option automatically enables the `--fix-db-names' and
     `--fix-table-names' options.  `--check-upgrade' was added in MySQL
     5.1.7.

   *  `--compress'

     Compress all information sent between the client and the server if
     both support compression.

   *  `--databases', `-B'

     Process all tables in the named databases. Normally, `mysqlcheck'
     treats the first name argument on the command line as a database
     name and following names as table names. With this option, it
     treats all name arguments as database names.

   *  `--debug[=DEBUG_OPTIONS]', `-# [DEBUG_OPTIONS]'

     Write a debugging log. A typical DEBUG_OPTIONS string is often
     `'d:t:o,FILE_NAME''.

   *  `--debug-check'

     Print some debugging information when the program exits.  This
     option was added in MySQL 5.1.21.

   *  `--debug-info'

     Print debugging information and memory and CPU usage statistics
     when the program exits. This option was added in MySQL 5.1.14.

   *  `--default-character-set=CHARSET_NAME'

     Use CHARSET_NAME as the default character set. See *Note
     charset-configuration::.

   *  `--extended', `-e'

     If you are using this option to check tables, it ensures that they
     are 100% consistent but takes a long time.

     If you are using this option to repair tables, it runs an extended
     repair that may not only take a long time to execute, but may
     produce a lot of garbage rows also!

   *  `--fast', `-F'

     Check only tables that have not been closed properly.

   *  `--fix-db-names'

     Convert database names to 5.1 format. Only database names that
     contain special characters are affected. This option was added in
     MySQL 5.1.7.

   *  `--fix-table-names'

     Convert table names to 5.1 format. Only table names that contain
     special characters are affected. This option was added in MySQL
     5.1.7. As of MySQL 5.1.23, this option also applies to views.

   *  `--force', `-f'

     Continue even if an SQL error occurs.

   *  `--host=HOST_NAME', `-h HOST_NAME'

     Connect to the MySQL server on the given host.

   *  `--medium-check', `-m'

     Do a check that is faster than an `--extended' operation. This
     finds only 99.99% of all errors, which should be good enough in
     most cases.

   *  `--optimize', `-o'

     Optimize the tables.

   *  `--password[=PASSWORD]', `-p[PASSWORD]'

     The password to use when connecting to the server. If you use the
     short option form (`-p'), you _cannot_ have a space between the
     option and the password. If you omit the PASSWORD value following
     the `--password' or `-p' option on the command line, you are
     prompted for one.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security::.

   *  `--pipe', `-W'

     On Windows, connect to the server via a named pipe. This option
     applies only for connections to a local server, and only if the
     server supports named-pipe connections.

   *  `--port=PORT_NUM', `-P PORT_NUM'

     The TCP/IP port number to use for the connection.

   *  `--protocol={TCP|SOCKET|PIPE|MEMORY}'

     The connection protocol to use for connecting to the server.  It
     is useful when the other connection parameters normally would
     cause a protocol to be used other than the one you want. For
     details on the allowable values, see *Note connecting::.

   *  `--quick', `-q'

     If you are using this option to check tables, it prevents the
     check from scanning the rows to check for incorrect links. This is
     the fastest check method.

     If you are using this option to repair tables, it tries to repair
     only the index tree. This is the fastest repair method.

   *  `--repair', `-r'

     Perform a repair that can fix almost anything except unique keys
     that are not unique.

   *  `--silent', `-s'

     Silent mode. Print only error messages.

   *  `--socket=PATH', `-S PATH'

     For connections to `localhost', the Unix socket file to use, or,
     on Windows, the name of the named pipe to use.

   *  `--ssl*'

     Options that begin with `--ssl' specify whether to connect to the
     server via SSL and indicate where to find SSL keys and
     certificates. See *Note ssl-options::.

   *  `--tables'

     Overrides the `--databases' or `-B' option. All name arguments
     following the option are regarded as table names.

   *  `--use-frm'

     For repair operations on `MyISAM' tables, get the table structure
     from the `.frm' file so that the table can be repaired even if the
     `.MYI' header is corrupted.

   *  `--user=USER_NAME', `-u USER_NAME'

     The MySQL username to use when connecting to the server.

   *  `--verbose', `-v'

     Verbose mode. Print information about the various stages of
     program operation.

   *  `--version', `-V'

     Display version information and exit.


File: manual.info,  Node: mysqldump,  Next: mysqlimport,  Prev: mysqlcheck,  Up: programs-client

4.5.4 `mysqldump' -- A Database Backup Program
----------------------------------------------

The `mysqldump' client is a backup program originally written by Igor
Romanenko. It can be used to dump a database or a collection of
databases for backup or transfer to another SQL server (not necessarily
a MySQL server). The dump typically contains SQL statements to create
the table, populate it, or both. However, `mysqldump' can also be used
to generate files in CSV, other delimited text, or XML format.

If you are doing a backup on the server and your tables all are
`MyISAM' tables, consider using the `mysqlhotcopy' instead because it
can accomplish faster backups and faster restores. See *Note
mysqlhotcopy::.

There are three general ways to invoke `mysqldump':

     shell> mysqldump [OPTIONS] DB_NAME [TABLES]
     shell> mysqldump [OPTIONS] --databases DB_NAME1 [DB_NAME2 DB_NAME3...]
     shell> mysqldump [OPTIONS] --all-databases

If you do not name any tables following DB_NAME or if you use the
`--databases' or `--all-databases' option, entire databases are dumped.

`mysqldump' does not dump the `INFORMATION_SCHEMA' database. If you
name that database explicitly on the command line, `mysqldump' silently
ignores it.

To get a list of the options your version of `mysqldump' supports,
execute `mysqldump --help'.

Some `mysqldump' options are shorthand for groups of other options.
`--opt' and `--compact' fall into this category. For example, use of
`--opt' is the same as specifying `--add-drop-table --add-locks
--create-options --disable-keys --extended-insert --lock-tables --quick
--set-charset'. Note that as of MySQL 5.1, all of the options that
`--opt' stands for also are on by default because `--opt' is on by
default.

To reverse the effect of a group option, uses its `--skip-XXX' form
(`--skip-opt' or `--skip-compact'). It is also possible to select only
part of the effect of a group option by following it with options that
enable or disable specific features. Here are some examples:

   * To select the effect of `--opt' except for some features, use the
     `--skip' option for each feature. For example, to disable extended
     inserts and memory buffering, use `--opt --skip-extended-insert
     --skip-quick'. (As of MySQL 5.1, `--skip-extended-insert
     --skip-quick' is sufficient because `--opt' is on by default.)

   * To reverse `--opt' for all features except index disabling and
     table locking, use `--skip-opt --disable-keys --lock-tables'.

When you selectively enable or disable the effect of a group option,
order is important because options are processed first to last. For
example, `--disable-keys --lock-tables --skip-opt' would not have the
intended effect; it is the same as `--skip-opt' by itself.

`mysqldump' can retrieve and dump table contents row by row, or it can
retrieve the entire content from a table and buffer it in memory before
dumping it. Buffering in memory can be a problem if you are dumping
large tables. To dump tables row by row, use the `--quick' option (or
`--opt', which enables `--quick').  The `--opt' option (and hence
`--quick') is enabled by default in MySQL 5.1; to enable memory
buffering, use `--skip-quick'.

If you are using a recent version of `mysqldump' to generate a dump to
be reloaded into a very old MySQL server, you should not use the
`--opt' or `--extended-insert' option. Use `--skip-opt' instead.

*Note*:

`mysqldump' from the MySQL 5.1.21 distribution cannot be used to create
dumps from MySQL server versions 5.1.20 and older. This issue is fixed
in MySQL 5.1.22. (Bug#30123 (http://bugs.mysql.com/30123))

*`mysqldump' Option Reference*

*Format*       *Config File*  *Description*                        *Introduction*
-add-drop-databaseadd-drop-databaseAdd a DROP DATABASE statement        
                              before each CREATE DATABASE          
                              statement                            
-add-drop-tableadd-drop-table Add a DROP TABLE statement before    
                              each CREATE TABLE statement          
-add-locks     add-locks      Surround each table dump with LOCK   
                              TABLES and UNLOCK TABLES  statements 
-all-databases all-databases  Dump all tables in all databases     
-allow-keywordsallow-keywords Allow creation of column names that  
                              are keywords                         
-all-tablespacesall-tablespacesAdds to a table dump all SQL         5.1.6
                              statements needed to create any      
                              tablespaces used by an NDB Cluster   
                              table                                
-comments      comments       Add comments to the dump file        
-compact       compact        Produce less verbose output          
-compatible=name[,name,...]compatible     Produce output that is more          
                              compatible with other database       
                              systems  or with older MySQL servers 
-complete-insertcomplete-insertUse complete INSERT statements that  
                              include column names                 
-create-optionscreate-options Include all MySQL-specific table     
                              options in the CREATE TABLE          
                              statements                           
-databases     databases      Dump several databases               
-debug[=debug_options]debug          Write a debugging log                
-debug-check   debug-check    Print debugging information when     5.1.21
                              the program exits                    
-debug-info    debug-info     Print debugging information, memory  5.1.14
                              and CPU statistics when the          
                              program exits                        
-delayed-insertdelayed-insert Write INSERT DELAYED statements      
                              rather than INSERT statements        
-delete-master-logsdelete-master-logsOn a master replication server,      
                              delete the binary logs after         
                              performing the dump operation        
-disable-keys  disable-keys   For each table, surround the INSERT  
                              statements with disable and  enable  
                              keys statements                      
-dump-date     dump-date      Include dump date in "Dump           5.1.23
                              completed on" comment if -comments   
                              is  given                            
-E             events         Dump events from the dumped          
                              databases                            
-extended-insertextended-insertUse multiple-row INSERT syntax that  
                              include several VALUES lists         
-fields-enclosed-by=stringfields-enclosed-byThis option is used with the -T      
                              option and has the same meaning as   
                              the corresponding clause for LOAD    
                              DATA INFILE                          
-fields-escaped-byfields-escaped-byThis option is used with the -T      
                              option and has the same meaning as   
                              the corresponding clause for LOAD    
                              DATA INFILE                          
-fields-optionally-enclosed-by=stringfields-optionally-enclosed-byThis option is used with the -T      
                              option and has the same meaning as   
                              the corresponding clause for LOAD    
                              DATA INFILE                          
-fields-terminated-by=stringfields-terminated-byThis option is used with the -T      
                              option and has the same meaning as   
                              the corresponding clause for LOAD    
                              DATA INFILE                          
-lock-all-tablesfirst-slave    Deprecated. Now renamed to           
                              -lock-all-tables                     
-flush-logs    flush-logs     Flush the MySQL server log files     
                              before starting the dump             
-flush-privilegesflush-privilegesEmit a FLUSH PRIVILEGES statement    
                              after dumping the mysql database     
-help                         Display help message and exit        
-hex-blob      hex-blob       Dump binary columns using            
                              hexadecimal notation (for example,   
                              'abc'  becomes 0x616263)             
-ignore-table=db_name.tbl_nameignore-table   Do not dump the given table          
-insert-ignore insert-ignore  Write INSERT statements with the     
                              IGNORE option                        
-lines-terminated-by=stringlines-terminated-byThis option is used with the -T      
                              option and has the same meaning as   
                              the corresponding clause for LOAD    
                              DATA INFILE                          
-lock-all-tableslock-all-tablesLock all tables across all databases 
-lock-tables   lock-tables    Lock all tables before dumping them  
-log-error=file_namelog-error      Append warnings and errors to the    5.1.18
                              named file                           
-master-data[=value]master-data    Write the binary log filename and    
                              position to the output               
-max_allowed_packet=valuemax_allowed_packetThe maximum packet length to send    
                              to or receive from the server        
-net_buffer_length=valuenet_buffer_lengthThe buffer size for TCP/IP and       
                              socket communication                 
-no-autocommit no-autocommit  Enclose the INSERT statements for    
                              each dumped table within SET         
                              AUTOCOMMIT=0 and COMMIT statements   
-no-create-db  no-create-db   This option suppresses the CREATE    
                              DATABASE statements                  
-no-create-infono-create-info Do not write CREATE TABLE            
                              statements that re-create each       
                              dumped  table                        
-no-data       no-data        Do not write any table row           
                              information   (that is, do not dump  
                              table contents)                      
-no-set-names  no-set-names   Turn off complete-insert             
-opt           opt            This option is shorthand; it is the  
                              same as specifying  -add-drop-table  
                              -add-locks -create-options           
                              -disable-keys  -extended-insert      
                              -lock-tables -quick -set-charset.    
-order-by-primaryorder-by-primarySorts each table's rows by its       
                              primary key, or by its first unique  
                              index                                
-password[=password]password       The password to use when connecting  
                              to the server                        
-pipe                         On Windows, connect to server via a  
                              named pipe                           
-port=port_num port           The TCP/IP port number to use for    
                              the connection                       
-quick         quick          Retrieve rows for a table from the   
                              server a row at a time               
-quote-names   quote-names    Quote database, table, and column    
                              names within backtick characters     
-replace       replace        Write REPLACE statements rather      
                              than INSERT statements               
-result-file=fileresult-file    Direct output to a given file        
-R             routines       Dump stored routines (functions and  
                              procedures) from the dumped          
                              databases                            
-set-charset   set-charset    Add SET NAMES default_character_set  
                              to the output                        
-single-transactionsingle-transactionThis option issues a BEGIN SQL       
                              statement before dumping data from   
                              the server                           
-skip-add-drop-tableskip-add-drop-tableDo not add                           
-skip-add-locksskip-add-locks Do not add locks                     
-skip-comments skip-comments  Do not add comments to the dump file 
-skip-compact  skip-compact   Turn off compact                     
-skip-disable-keysskip-disable-keysDo not disable keys                  
-skip-extended-insertskip-extended-insertTurn off extended-insert             
-skip-opt      skip-opt       Turn off the options set by opt      
-skip-quick    skip-quick     Do not retrieve rows for a table     
                              from the server a row at a time      
-skip-quote-namesskip-quote-namesTurn off quote names                 
-skip-set-charsetskip-set-charsetSuppress the SET NAMES statement     
-skip-triggers skip-triggers  Turn off triggers                    
-skip-tz-utc   skip-tz-utc    Turn off tz-utc                      
-ssl-ca=file_namessl-ca         The path to a file that contains a   
                              list of trusted SSL CAs              
-ssl-capath=directory_namessl-capath     The path to a directory that         
                              contains trusted SSL CA              
                              certificates  in PEM format          
-ssl-cert=file_namessl-cert       The name of the SSL certificate      
                              file to use for establishing a       
                              secure connection                    
-ssl-cipher=cipher_listssl-cipher     A list of allowable ciphers to use   
                              for SSL encryption                   
-ssl-key=file_namessl-key        The name of the SSL key file to use  
                              for establishing a secure            
                              connection                           
-ssl-verify-server-certssl-verify-server-certThe server's Common Name value in    
                              its certificate is verified          
                              against the hostname used when       
                              connecting to the server             
-tab=path      tab            Produce tab-separated data files     
-tables        tables         Override the -databases or -B option 
-triggers      triggers       Dump triggers for each dumped table  
-tz-utc        tz-utc         Add SET TIME_ZONE='+00:00' to the    
                              dump file                            
-verbose                      Verbose mode                         
-version                      Display version information and exit 
-where='where_condition'where          Dump only rows selected by the       
                              given WHERE condition                
-xml           xml            Produce XML output                   

`mysqldump' supports the following options:

   *  `--help', `-?'

     Display a help message and exit.

   *  `--add-drop-database'

     Add a `DROP DATABASE' statement before each `CREATE DATABASE'
     statement.

   *  `--add-drop-table'

     Add a `DROP TABLE' statement before each `CREATE TABLE' statement.

   *  `--add-locks'

     Surround each table dump with `LOCK TABLES' and `UNLOCK TABLES'
     statements. This results in faster inserts when the dump file is
     reloaded.  See *Note insert-speed::.

   *  `--all-databases', `-A'

     Dump all tables in all databases. This is the same as using the
     `--databases' option and naming all the databases on the command
     line.

   *  `--all-tablespaces', `-Y'

     Adds to a table dump all SQL statements needed to create any
     tablespaces used by an `NDBCLUSTER' table.  This information is
     not otherwise included in the output from `mysqldump'. This option
     is currently relevant only to MySQL Cluster tables.

     This option was added in MySQL 5.1.6.

   *  `--allow-keywords'

     Allow creation of column names that are keywords. This works by
     prefixing each column name with the table name.

   *  `--character-sets-dir=PATH'

     The directory where character sets are installed. See *Note
     charset-configuration::.

   *  `--comments', `-i'

     Write additional information in the dump file such as program
     version, server version, and host. This option is enabled by
     default. To suppress this additional information, use
     `--skip-comments'.

   *  `--compact'

     Produce less verbose output. This option enables the
     `--skip-add-drop-table', `--skip-add-locks', `--skip-comments',
     `--skip-disable-keys', and `--skip-set-charset' options.

     *Note*:

     Prior to release 5.1.21, this option did not create valid SQL if
     the database dump contained views. The recreation of views
     requires the creation and removal of temporary tables and this
     option suppressed the removal of those temporary tables. As a
     workaround, use `--compact' with the `--add-drop-table' option and
     then manually adjust the dump file.

   *  `--compatible=NAME'

     Produce output that is more compatible with other database systems
     or with older MySQL servers. The value of `name' can be `ansi',
     `mysql323', `mysql40', `postgresql', `oracle', `mssql', `db2',
     `maxdb', `no_key_options', `no_table_options', or
     `no_field_options'. To use several values, separate them by
     commas. These values have the same meaning as the corresponding
     options for setting the server SQL mode. See *Note
     server-sql-mode::.

     This option does not guarantee compatibility with other servers.
     It only enables those SQL mode values that are currently available
     for making dump output more compatible.  For example,
     `--compatible=oracle' does not map data types to Oracle types or
     use Oracle comment syntax.

     _This option requires a server version of 4.1.0 or higher_. With
     older servers, it does nothing.

   *  `--complete-insert', `-c'

     Use complete `INSERT' statements that include column names.

   *  `--compress', `-C'

     Compress all information sent between the client and the server if
     both support compression.

   *  `--create-options'

     Include all MySQL-specific table options in the `CREATE TABLE'
     statements.

   *  `--databases', `-B'

     Dump several databases. Normally, `mysqldump' treats the first
     name argument on the command line as a database name and following
     names as table names. With this option, it treats all name
     arguments as database names. `CREATE DATABASE' and `USE'
     statements are included in the output before each new database.

   *  `--debug[=DEBUG_OPTIONS]', `-# [DEBUG_OPTIONS]'

     Write a debugging log. The DEBUG_OPTIONS string is often
     `'d:t:o,FILE_NAME''.  The default value is
     `'d:t:o,/tmp/mysqldump.trace''.

   *  `--debug-check'

     Print some debugging information when the program exits.  This
     option was added in MySQL 5.1.21.

   *  `--debug-info'

     Print debugging information and memory and CPU usage statistics
     when the program exits. This option was added in MySQL 5.1.14.

   *  `--default-character-set=CHARSET_NAME'

     Use CHARSET_NAME as the default character set. See *Note
     charset-configuration::.  If no character set is specified,
     `mysqldump' uses `utf8', and earlier versions use `latin1'.

     This option has no effect for output data files produced by using
     the `--tab' option. See the description for that option.

   *  `--delayed-insert'

     Write `INSERT DELAYED' statements rather than `INSERT' statements.

   *  `--delete-master-logs'

     On a master replication server, delete the binary logs after
     performing the dump operation. This option automatically enables
     `--master-data'.

   *  `--disable-keys', `-K'

     For each table, surround the `INSERT' statements with `/*!40000
     ALTER TABLE TBL_NAME DISABLE KEYS */;' and `/*!40000 ALTER TABLE
     TBL_NAME ENABLE KEYS */;' statements. This makes loading the dump
     file faster because the indexes are created after all rows are
     inserted. This option is effective only for non-unique indexes of
     `MyISAM' tables.

   *  `--dump-date'

     `mysqldump' produces a `-- Dump completed on DATE' comment at the
     end of the dump if the `--comments' option is given. However, the
     date causes dump files for identical data take at different times
     to appear to be different.  `--dump-date' and `--skip-dump-date'
     control whether the date is added to the comment. The default is
     `--dump-date' (include the date in the comment).
     `--skip-dump-date' suppresses date printing. This option was added
     in MySQL 5.1.23.

   *  `--events', `-E'

     Dump events from the dumped databases. This option was added in
     MySQL 5.1.8.

   *  `--extended-insert', `-e'

     Use multiple-row `INSERT' syntax that include several `VALUES'
     lists. This results in a smaller dump file and speeds up inserts
     when the file is reloaded.

   *  `--fields-terminated-by=...',

     `--fields-enclosed-by=...',

     `--fields-optionally-enclosed-by=...',

     `--fields-escaped-by=...'

     These options are used with the `-T' option and have the same
     meaning as the corresponding clauses for `LOAD DATA INFILE'. See
     *Note load-data::.

   *  `--first-slave', `-x'

     Deprecated. Now renamed to `--lock-all-tables'.

   *  `--flush-logs', `-F'

     Flush the MySQL server log files before starting the dump.  This
     option requires the `RELOAD' privilege. Note that if you use this
     option in combination with the `--all-databases' (or `-A') option,
     the logs are flushed _for each database dumped_. The exception is
     when using `--lock-all-tables' or `--master-data': In this case,
     the logs are flushed only once, corresponding to the moment that
     all tables are locked. If you want your dump and the log flush to
     happen at exactly the same moment, you should use `--flush-logs'
     together with either `--lock-all-tables' or `--master-data'.

   *  `--flush-privileges'

     Emit a `FLUSH PRIVILEGES' statement after dumping the `mysql'
     database. This option should be used any time the dump contains the
     `mysql' database and any other database that depends on the data
     in the `mysql' database for proper restoration. This option was
     added in MySQL 5.1.12.

   *  `--force', `-f'

     Continue even if an SQL error occurs during a table dump.

     One use for this option is to cause `mysqldump' to continue
     executing even when it encounters a view that has become invalid
     because the defintion refers to a table that has been dropped.
     Without `--force', `mysqldump' exits with an error message. With
     `--force', `mysqldump' prints the error message, but it also
     writes a SQL comment containing the view definition to the dump
     output and continues executing.

   *  `--host=HOST_NAME', `-h HOST_NAME'

     Dump data from the MySQL server on the given host. The default
     host is `localhost'.

   *  `--hex-blob'

     Dump binary columns using hexadecimal notation (for example,
     `'abc'' becomes `0x616263'). The affected data types are `BINARY',
     `VARBINARY', `BLOB', and `BIT'.

   *  `--ignore-table=DB_NAME.TBL_NAME'

     Do not dump the given table, which must be specified using both
     the database and table names. To ignore multiple tables, use this
     option multiple times.

   *  `--insert-ignore'

     Write `INSERT' statements with the `IGNORE' option.

   *  `--lines-terminated-by=...'

     This option is used with the `-T' option and has the same meaning
     as the corresponding clause for `LOAD DATA INFILE'. See *Note
     load-data::.

   *  `--lock-all-tables', `-x'

     Lock all tables across all databases. This is achieved by
     acquiring a global read lock for the duration of the whole dump.
     This option automatically turns off `--single-transaction' and
     `--lock-tables'.

   *  `--lock-tables', `-l'

     Lock all tables before dumping them. The tables are locked with
     `READ LOCAL' to allow concurrent inserts in the case of `MyISAM'
     tables. For transactional tables such as `InnoDB' and `BDB',
     `--single-transaction' is a much better option, because it does
     not need to lock the tables at all.

     Please note that when dumping multiple databases, `--lock-tables'
     locks tables for each database separately. Therefore, this option
     does not guarantee that the tables in the dump file are logically
     consistent between databases. Tables in different databases may be
     dumped in completely different states.

   *  `--log-error=FILE_NAME'

     Append warnings and errors to the named file. This option was
     added in MySQL 5.1.18.

   *  `--master-data[=VALUE]'

     Use this option to dump a master replication server to produce a
     dump file that can be used to set up another server as a slave of
     the master. It causes the dump output to include a `CHANGE MASTER
     TO' statement that indicates the binary log coordinates (filename
     and position) of the dumped server. These are the master server
     coordinates from which the slave should start replicating.

     If the option value is 2, the `CHANGE MASTER TO' statement is
     written as an SQL comment, and thus is informative only; it has no
     effect when the dump file is reloaded. If the option value is 1,
     the statement takes effect when the dump file is reloaded. If the
     option value is not specified, the default value is 1.

     This option requires the `RELOAD' privilege and the binary log
     must be enabled.

     The `--master-data' option automatically turns off
     `--lock-tables'. It also turns on `--lock-all-tables', unless
     `--single-transaction' also is specified, in which case, a global
     read lock is acquired only for a short time at the beginning of
     the dump (see the description for `--single-transaction'). In all
     cases, any action on logs happens at the exact moment of the dump.

     It is also possible to set up a slave by dumping an existing slave
     of the master. To do this, use the following procedure on the
     existing slave:

       1. Stop the slave's SQL thread and get its current status:

               mysql> STOP SLAVE SQL_THREAD;
               mysql> SHOW SLAVE STATUS;

       2. From the output of the SHOW SLAVE STATUS statement, get the
          binary log coordinates of the master server from which the
          new slave should start replicating. These coordinates are the
          values of the Relay_Master_Log_File and Exec_Master_Log_Pos
          values. Denote those values as file_name and file_pos.

       3. Dump the slave server:

               shell> mysqldump --master-data=2 --all-databases > dumpfile

       4. Restart the slave:

               mysql> START SLAVE;

       5. On the new slave, reload the dump file:

               shell> mysql < dumpfile

       6. On the new slave, set the replication coordinates to those of
          the master server obtained earlier:

               mysql> CHANGE MASTER TO
                   -> MASTER_LOG_FILE = 'file_name', MASTER_LOG_POS = file_pos;

          The `CHANGE MASTER TO' statement might also need other
          parameters, such as `MASTER_HOST' to point the slave to the
          correct master server host. Add any such parameters as
          necessary.

   *  `--no-autocommit'

     Enclose the `INSERT' statements for each dumped table within `SET
     AUTOCOMMIT=0' and `COMMIT' statements.

   *  `--no-create-db', `-n'

     This option suppresses the `CREATE DATABASE' statements that are
     otherwise included in the output if the `--databases' or
     `--all-databases' option is given.

   *  `--no-create-info', `-t'

     Do not write `CREATE TABLE' statements that re-create each dumped
     table.

   *  `--no-data', `-d'

     Do not write any table row information (that is, do not dump table
     contents). This is very useful if you want to dump only the
     `CREATE TABLE' statement for the table.

   *  `--opt'

     This option is shorthand; it is the same as specifying
     `--add-drop-table --add-locks --create-options --disable-keys
     --extended-insert --lock-tables --quick --set-charset'. It should
     give you a fast dump operation and produce a dump file that can be
     reloaded into a MySQL server quickly.

     _The `--opt' option is enabled by default. Use `--skip-opt' to
     disable it._ See the discussion at the beginning of this section
     for information about selectively enabling or disabling certain of
     the options affected by `--opt'.

   *  `--order-by-primary'

     Sorts each table's rows by its primary key, or by its first unique
     index, if such an index exists. This is useful when dumping a
     `MyISAM' table to be loaded into an `InnoDB' table, but will make
     the dump itself take considerably longer.

   *  `--password[=PASSWORD]', `-p[PASSWORD]'

     The password to use when connecting to the server. If you use the
     short option form (`-p'), you _cannot_ have a space between the
     option and the password. If you omit the PASSWORD value following
     the `--password' or `-p' option on the command line, you are
     prompted for one.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security::.

   *  `--pipe', `-W'

     On Windows, connect to the server via a named pipe. This option
     applies only for connections to a local server, and only if the
     server supports named-pipe connections.

   *  `--port=PORT_NUM', `-P PORT_NUM'

     The TCP/IP port number to use for the connection.

   *  `--protocol={TCP|SOCKET|PIPE|MEMORY}'

     The connection protocol to use for connecting to the server.  It
     is useful when the other connection parameters normally would
     cause a protocol to be used other than the one you want. For
     details on the allowable values, see *Note connecting::.

   *  `--quick', `-q'

     This option is useful for dumping large tables. It forces
     `mysqldump' to retrieve rows for a table from the server a row at
     a time rather than retrieving the entire row set and buffering it
     in memory before writing it out.

   *  `--quote-names', `-Q'

     Quote database, table, and column names within ```'' characters.
     If the `ANSI_QUOTES' SQL mode is enabled, names are quoted within
     ``"'' characters. This option is enabled by default. It can be
     disabled with `--skip-quote-names', but this option should be
     given after any option such as `--compatible' that may enable
     `--quote-names'.

   *  `--replace'

     Write `REPLACE' statements rather than `INSERT' statements.
     Available as of MySQL 5.1.3.

   *  `--result-file=FILE_NAME', `-r FILE_NAME'

     Direct output to a given file. This option should be used on
     Windows to prevent newline ``\n'' characters from being converted
     to ``\r\n'' carriage return/newline sequences. The result file is
     created and its contents overwritten, even if an error occurs while
     generating the dump. The previous contents are lost.

   *  `--routines', `-R'

     Dump stored routines (functions and procedures) from the dumped
     databases. Use of this option requires the `SELECT' privilege for
     the `mysql.proc' table. The output generated by using `--routines'
     contains `CREATE PROCEDURE' and `CREATE FUNCTION' statements to
     re-create the routines. However, these statements do not include
     attributes such as the routine creation and modification
     timestamps. This means that when the routines are reloaded, they
     will be created with the timestamps equal to the reload time.

     If you require routines to be re-created with their original
     timestamp attributes, do not use `--routines'. Instead, dump and
     reload the contents of the `mysql.proc' table directly, using a
     MySQL account that has appropriate privileges for the `mysql'
     database.

     This option was added in MySQL 5.1.2. Before that, stored routines
     are not dumped. Routine `DEFINER' values are not dumped until
     MySQL 5.1.8. This means that before 5.1.8, when routines are
     reloaded, they will be created with the definer set to the
     reloading user. If you require routines to be re-created with
     their original definer, dump and load the contents of the
     `mysql.proc' table directly as described earlier.

   *  `--set-charset'

     Add `SET NAMES DEFAULT_CHARACTER_SET' to the output. This option
     is enabled by default. To suppress the `SET NAMES' statement, use
     `--skip-set-charset'.

   *  `--single-transaction'

     This option issues a `BEGIN' SQL statement before dumping data
     from the server. It is useful only with transactional tables such
     as `InnoDB', because then it dumps the consistent state of the
     database at the time when `BEGIN' was issued without blocking any
     applications.

     When using this option, you should keep in mind that only `InnoDB'
     tables are dumped in a consistent state. For example, any `MyISAM'
     or `MEMORY' tables dumped while using this option may still change
     state.

     While a `--single-transaction' dump is in process, to ensure a
     valid dump file (correct table contents and binary log position),
     no other connection should use the following statements: `ALTER
     TABLE', `DROP TABLE', `RENAME TABLE', `TRUNCATE TABLE'. A
     consistent read is not isolated from those statements, so use of
     them on a table to be dumped can cause the `SELECT' performed by
     `mysqldump' to retrieve the table contents to obtain incorrect
     contents or fail.

     This option is not supported for MySQL Cluster tables; the results
     cannot be guaranteed to be consistent due to the fact that the
     `NDBCLUSTER' storage engine supports only the `READ_COMMITTED'
     transaction isolation level. You should always use `NDB' backup
     and restore instead.

     The `--single-transaction' option and the `--lock-tables' option
     are mutually exclusive, because `LOCK TABLES' causes any pending
     transactions to be committed implicitly.

     To dump large tables, you should combine this option with
     `--quick'.

   *  `--skip-comments'

     See the description for the `--comments' option.

   *  `--skip-opt'

     See the description for the `--opt' option.

   *  `--socket=PATH', `-S PATH'

     For connections to `localhost', the Unix socket file to use, or,
     on Windows, the name of the named pipe to use.

   *  `--ssl*'

     Options that begin with `--ssl' specify whether to connect to the
     server via SSL and indicate where to find SSL keys and
     certificates. See *Note ssl-options::.

   *  `--tab=PATH', `-T PATH'

     Produce tab-separated data files. For each dumped table,
     `mysqldump' creates a `TBL_NAME.sql' file that contains the
     `CREATE TABLE' statement that creates the table, and a
     `TBL_NAME.txt' file that contains its data. The option value is the
     directory in which to write the files.

     By default, the `.txt' data files are formatted using tab
     characters between column values and a newline at the end of each
     line. The format can be specified explicitly using the
     `--fields-XXX' and `--lines-terminated-by' options.

     Column values are dumped using the `binary' character set and the
     `--default-character-set' option is ignored.  In effect, there is
     no character set conversion. If a table contains columns in
     several character sets, the output data file will as well and you
     may not be able to reload the file correctly.

     *Note*:

     This option should be used only when `mysqldump' is run on the
     same machine as the `mysqld' server. You must have the `FILE'
     privilege, and the server must have permission to write files in
     the directory that you specify.

   *  `--tables'

     Override the `--databases' or `-B' option. `mysqldump' regards all
     name arguments following the option as table names.

   * `--triggers'

     Dump triggers for each dumped table. This option is enabled by
     default; disable it with `--skip-triggers'.

   *  `--tz-utc'

     This option enables `TIMESTAMP' columns to be dumped and reloaded
     between servers in different time zones. `mysqldump' sets its
     connection time zone to UTC and adds `SET TIME_ZONE='+00:00'' to
     the dump file. Without this option, `TIMESTAMP' columns are dumped
     and reloaded in the time zones local to the source and destination
     servers, which can cause the values to change.  `--tz-utc' also
     protects against changes due to daylight saving time. `--tz-utc' is
     enabled by default. To disable it, use `--skip-tz-utc'. This
     option was added in MySQL 5.1.2.

   *  `--user=USER_NAME', `-u USER_NAME'

     The MySQL username to use when connecting to the server.

   *  `--verbose', `-v'

     Verbose mode. Print more information about what the program does.

   *  `--version', `-V'

     Display version information and exit.

   *  `--where='WHERE_CONDITION'', `-w 'WHERE_CONDITION''

     Dump only rows selected by the given `WHERE' condition. Quotes
     around the condition are mandatory if it contains spaces or other
     characters that are special to your command interpreter.

     Examples:

          --where="user='jimf'"
          -w"userid>1"
          -w"userid<1"

   *  `--xml', `-X'

     Write dump output as well-formed XML.

     *`NULL', `'NULL'', and Empty Values*: For some column named
     COLUMN_NAME, the `NULL' value, an empty string, and the string
     value `'NULL'' are distinguished from one another in the output
     generated by this option as follows:

     *Value*:                           *XML Representation*:
     `NULL' (_unknown value_)           `<field name="COLUMN_NAME"
                                        xsi:nil="true" />'
     `''' (_empty string_)              `<field
                                        name="COLUMN_NAME"></field>'
     `'NULL'' (_string value_)          `<field
                                        name="COLUMN_NAME">NULL</field>'

     Beginning with MySQL 5.1.12, the output from the `mysql' client
     when run using the `--xml' option also follows these rules. (See
     *Note mysql-command-options::.)

     Beginning with MySQL 5.1.18, XML output from `mysqldump' includes
     the XML namespace, as shown here:

          shell> mysqldump --xml -u root world City
          <?xml version="1.0"?>
          <mysqldump xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
          <database name="world">
          <table_structure name="City">
          <field Field="ID" Type="int(11)" Null="NO" Key="PRI" Extra="auto_increment" />
          <field Field="Name" Type="char(35)" Null="NO" Key="" Default="" Extra="" />
          <field Field="CountryCode" Type="char(3)" Null="NO" Key="" Default="" Extra="" />
          <field Field="District" Type="char(20)" Null="NO" Key="" Default="" Extra="" />
          <field Field="Population" Type="int(11)" Null="NO" Key="" Default="0" Extra="" />
          <key Table="City" Non_unique="0" Key_name="PRIMARY" Seq_in_index="1" Column_name="ID" Collation="A" Cardinality="4079"
          Null="" Index_type="BTREE" Comment="" />
          <options Name="City" Engine="MyISAM" Version="10" Row_format="Fixed" Rows="4079" Avg_row_length="67" Data_length="27329
          3" Max_data_length="18858823439613951" Index_length="43008" Data_free="0" Auto_increment="4080" Create_time="2007-03-31 01:47:01" Updat
          e_time="2007-03-31 01:47:02" Collation="latin1_swedish_ci" Create_options="" Comment="" />
          </table_structure>
          <table_data name="City">
          <row>
          <field name="ID">1</field>
          <field name="Name">Kabul</field>
          <field name="CountryCode">AFG</field>
          <field name="District">Kabol</field>
          <field name="Population">1780000</field>
          </row>

          ...

          <row>
          <field name="ID">4079</field>
          <field name="Name">Rafah</field>
          <field name="CountryCode">PSE</field>
          <field name="District">Rafah</field>
          <field name="Population">92020</field>
          </row>
          </table_data>
          </database>
          </mysqldump>

You can also set the following variables by using `--VAR_NAME=VALUE'
syntax:

   * `max_allowed_packet'

     The maximum size of the buffer for client/server communication.
     The maximum is 1GB.

   *  `net_buffer_length'

     The initial size of the buffer for client/server communication.
     When creating multiple-row-insert statements (as with option
     `--extended-insert' or `--opt'), `mysqldump' creates rows up to
     `net_buffer_length' length. If you increase this variable, you
     should also ensure that the `net_buffer_length' variable in the
     MySQL server is at least this large.

The most common use of `mysqldump' is probably for making a backup of
an entire database:

     shell> mysqldump DB_NAME > BACKUP-FILE.SQL

You can read the dump file back into the server like this:

     shell> mysql DB_NAME < BACKUP-FILE.SQL

Or like this:

     shell> mysql -e "source /PATH-TO-BACKUP/BACKUP-FILE.SQL" DB_NAME

`mysqldump' is also very useful for populating databases by copying
data from one MySQL server to another:

     shell> mysqldump --opt DB_NAME | mysql --host=REMOTE_HOST -C DB_NAME

It is possible to dump several databases with one command:

     shell> mysqldump --databases DB_NAME1 [DB_NAME2 ...] > my_databases.sql

To dump all databases, use the `--all-databases' option:

     shell> mysqldump --all-databases > all_databases.sql

For `InnoDB' tables, `mysqldump' provides a way of making an online
backup:

     shell> mysqldump --all-databases --single-transaction > all_databases.sql

This backup just needs to acquire a global read lock on all tables
(using `FLUSH TABLES WITH READ LOCK') at the beginning of the dump. As
soon as this lock has been acquired, the binary log coordinates are
read and the lock is released. If and only if one long updating
statement is running when the `FLUSH' statement is issued, the MySQL
server may get stalled until that long statement finishes, and then the
dump becomes lock-free. If the update statements that the MySQL server
receives are short (in terms of execution time), the initial lock
period should not be noticeable, even with many updates.

For point-in-time recovery (also known as `roll-forward,' when you need
to restore an old backup and replay the changes that happened since
that backup), it is often useful to rotate the binary log (see *Note
binary-log::) or at least know the binary log coordinates to which the
dump corresponds:

     shell> mysqldump --all-databases --master-data=2 > all_databases.sql

Or:

     shell> mysqldump --all-databases --flush-logs --master-data=2
                   > all_databases.sql

The `--master-data' and `--single-transaction' options can be used
simultaneously, which provides a convenient way to make an online
backup suitable for point-in-time recovery if tables are stored using
the `InnoDB' storage engine.

For more information on making backups, see *Note backup::, and *Note
backup-strategy-example::.

If you encounter problems backing up views, please read the section
that covers restrictions on views which describes a workaround for
backing up views when this fails due to insufficient privileges. See
*Note view-restrictions::.

MySQL Enterprise

MySQL Enterprise subscribers will find more information about
`mysqldump' in the Knowledge Base article, How Can I Avoid Inserting
Duplicate Rows From a Dump File?
(https://kb.mysql.com/view.php?id=5285).  Access to the MySQL Knowledge
Base collection of articles is one of the advantages of subscribing to
MySQL Enterprise. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: mysqlimport,  Next: mysqlshow,  Prev: mysqldump,  Up: programs-client

4.5.5 `mysqlimport' -- A Data Import Program
--------------------------------------------

The `mysqlimport' client provides a command-line interface to the `LOAD
DATA INFILE' SQL statement. Most options to `mysqlimport' correspond
directly to clauses of `LOAD DATA INFILE' syntax. See *Note load-data::.

Invoke `mysqlimport' like this:

     shell> mysqlimport [OPTIONS] DB_NAME TEXTFILE1 [TEXTFILE2 ...]

For each text file named on the command line, `mysqlimport' strips any
extension from the filename and uses the result to determine the name
of the table into which to import the file's contents. For example,
files named `patient.txt', `patient.text', and `patient' all would be
imported into a table named `patient'.

*`mysqlimport' Option Reference*

*Format*       *Config File*  *Description*                        *Introduction*
-columns=column_listcolumns        This option takes a comma-separated  
                              list of column names as its  value   
-compress      compress       Compress all information sent        
                              between the client and the server    
-debug[=debug_options]debug          Write a debugging log                
-debug-check   debug-check    Print debugging information when     5.1.21
                              the program exits                    
-debug-info    debug-info     Print debugging information, memory  5.1.14
                              and CPU statistics when the          
                              program exits                        
-default-character-set=charset_namedefault-character-setUse charset_name as the default      
                              character set                        
-delete        delete         Empty the table before importing     
                              the text file                        
-fields-enclosed-by=stringfields-enclosed-byThis option has the same meaning as  
                              the corresponding clause for  LOAD   
                              DATA INFILE                          
-fields-escaped-byfields-escaped-byThis option has the same meaning as  
                              the corresponding clause for  LOAD   
                              DATA INFILE                          
-fields-optionally-enclosed-by=stringfields-optionally-enclosed-byThis option has the same meaning as  
                              the corresponding clause for  LOAD   
                              DATA INFILE                          
-fields-terminated-by=stringfields-terminated-by- This option has the same meaning   
                              as the corresponding clause  for     
                              LOAD DATA INFILE                     
-force         force          Continue even if an SQL error occurs 
-help                         Display help message and exit        
-host=host_namehost           Connect to the MySQL server on the   
                              given host                           
-ignore        ignore         See the description for the          
                              -replace option                      
-ignore-lines=#ignore-lines   Ignore the first N lines of the      
                              data file                            
-lines-terminated-by=stringlines-terminated-byThis option has the same meaning as  
                              the corresponding clause for  LOAD   
                              DATA INFILE                          
-local         local          Read input files locally from the    
                              client host                          
-lock-tables   lock-tables    Lock all tables for writing before   
                              processing any text files            
-low-priority  low-priority   Use LOW_PRIORITY when loading the    
                              table.                               
-password[=password]password       The password to use when connecting  
                              to the server                        
-pipe                         On Windows, connect to server via a  
                              named pipe                           
-port=port_num port           The TCP/IP port number to use for    
                              the connection                       
-protocol=type protocol       The connection protocol to use       
-replace       replace        The -replace and -ignore options     
                              control handling of input rows       
                              that duplicate existing rows on      
                              unique key values                    
-silent        silent         Produce output only when errors      
                              occur                                
-socket=path   socket         For connections to localhost         
-ssl-ca=file_namessl-ca         The path to a file that contains a   
                              list of trusted SSL CAs              
-ssl-capath=directory_namessl-capath     The path to a directory that         
                              contains trusted SSL CA              
                              certificates  in PEM format          
-ssl-cert=file_namessl-cert       The name of the SSL certificate      
                              file to use for establishing a       
                              secure connection                    
-ssl-cipher=cipher_listssl-cipher     A list of allowable ciphers to use   
                              for SSL encryption                   
-ssl-key=file_namessl-key        The name of the SSL key file to use  
                              for establishing a secure            
                              connection                           
-ssl-verify-server-certssl-verify-server-certThe server's Common Name value in    
                              its certificate is verified          
                              against the hostname used when       
                              connecting to the server             
-user=user_name,user           The MySQL username to use when       
                              connecting to the server             
-use-threads=# use-threads    The number of threads for parallel   5.1.7
                              file-loading                         
-verbose                      Verbose mode                         
-version                      Display version information and exit 

`mysqlimport' supports the following options:

   *  `--help', `-?'

     Display a help message and exit.

   *  `--character-sets-dir=PATH'

     The directory where character sets are installed. See *Note
     charset-configuration::.

   *  `--columns=COLUMN_LIST', `-c COLUMN_LIST'

     This option takes a comma-separated list of column names as its
     value. The order of the column names indicates how to match data
     file columns with table columns.

   *  `--compress', `-C'

     Compress all information sent between the client and the server if
     both support compression.

   *  `--debug[=DEBUG_OPTIONS]', `-# [DEBUG_OPTIONS]'

     Write a debugging log. The DEBUG_OPTIONS string often is
     `'d:t:o,FILE_NAME''.

   *  `--debug-check'

     Print some debugging information when the program exits.  This
     option was added in MySQL 5.1.21.

   *  `--debug-info'

     Print debugging information and memory and CPU usage statistics
     when the program exits. This option was added in MySQL 5.1.14.

   *  `--default-character-set=CHARSET_NAME'

     Use CHARSET_NAME as the default character set. See *Note
     charset-configuration::.

   *  `--delete', `-D'

     Empty the table before importing the text file.

   *  `--fields-terminated-by=...',

     `--fields-enclosed-by=...',

     `--fields-optionally-enclosed-by=...',

     `--fields-escaped-by=...'

     These options have the same meaning as the corresponding clauses
     for `LOAD DATA INFILE'. See *Note load-data::.

   *  `--force', `-f'

     Ignore errors. For example, if a table for a text file does not
     exist, continue processing any remaining files. Without `--force',
     `mysqlimport' exits if a table does not exist.

   *  `--host=HOST_NAME', `-h HOST_NAME'

     Import data to the MySQL server on the given host. The default
     host is `localhost'.

   *  `--ignore', `-i'

     See the description for the `--replace' option.

   *  `--ignore-lines=N'

     Ignore the first N lines of the data file.

   *  `--lines-terminated-by=...'

     This option has the same meaning as the corresponding clause for
     `LOAD DATA INFILE'. For example, to import Windows files that have
     lines terminated with carriage return/linefeed pairs, use
     `--lines-terminated-by="\r\n"'. (You might have to double the
     backslashes, depending on the escaping conventions of your command
     interpreter.) See *Note load-data::.

   *  `--local', `-L'

     Read input files locally from the client host.

     MySQL Enterprise

     For expert advice on the security implications of enabling
     `LOCAL', subscribe to the MySQL Enterprise Monitor. For more
     information, see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   *  `--lock-tables', `-l'

     Lock _all_ tables for writing before processing any text files.
     This ensures that all tables are synchronized on the server.

   *  `--low-priority'

     Use `LOW_PRIORITY' when loading the table.  This affects only
     storage engines that use only table-level locking (`MyISAM',
     `MEMORY', `MERGE').

   *  `--password[=PASSWORD]', `-p[PASSWORD]'

     The password to use when connecting to the server. If you use the
     short option form (`-p'), you _cannot_ have a space between the
     option and the password. If you omit the PASSWORD value following
     the `--password' or `-p' option on the command line, you are
     prompted for one.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security::.

   *  `--pipe', `-W'

     On Windows, connect to the server via a named pipe. This option
     applies only for connections to a local server, and only if the
     server supports named-pipe connections.

   *  `--port=PORT_NUM', `-P PORT_NUM'

     The TCP/IP port number to use for the connection.

   *  `--protocol={TCP|SOCKET|PIPE|MEMORY}'

     The connection protocol to use for connecting to the server.  It
     is useful when the other connection parameters normally would
     cause a protocol to be used other than the one you want. For
     details on the allowable values, see *Note connecting::.

   *  `--replace', `-r'

     The `--replace' and `--ignore' options control handling of input
     rows that duplicate existing rows on unique key values. If you
     specify `--replace', new rows replace existing rows that have the
     same unique key value. If you specify `--ignore', input rows that
     duplicate an existing row on a unique key value are skipped. If
     you do not specify either option, an error occurs when a duplicate
     key value is found, and the rest of the text file is ignored.

   *  `--silent', `-s'

     Silent mode. Produce output only when errors occur.

   *  `--socket=PATH', `-S PATH'

     For connections to `localhost', the Unix socket file to use, or,
     on Windows, the name of the named pipe to use.

   *  `--ssl*'

     Options that begin with `--ssl' specify whether to connect to the
     server via SSL and indicate where to find SSL keys and
     certificates. See *Note ssl-options::.

   *  `--user=USER_NAME', `-u USER_NAME'

     The MySQL username to use when connecting to the server.

   *  `--use-threads=N'

     Load files in parallel using N threads. This option was added in
     MySQL 5.1.7.

   *  `--verbose', `-v'

     Verbose mode. Print more information about what the program does.

   *  `--version', `-V'

     Display version information and exit.

Here is a sample session that demonstrates use of `mysqlimport':

     shell> mysql -e 'CREATE TABLE imptest(id INT, n VARCHAR(30))' test
     shell> ed
     a
     100     Max Sydow
     101     Count Dracula
     .
     w imptest.txt
     32
     q
     shell> od -c imptest.txt
     0000000   1   0   0  \t   M   a   x       S   y   d   o   w  \n   1   0
     0000020   1  \t   C   o   u   n   t       D   r   a   c   u   l   a  \n
     0000040
     shell> mysqlimport --local test imptest.txt
     test.imptest: Records: 2  Deleted: 0  Skipped: 0  Warnings: 0
     shell> mysql -e 'SELECT * FROM imptest' test
     +------+---------------+
     | id   | n             |
     +------+---------------+
     |  100 | Max Sydow     |
     |  101 | Count Dracula |
     +------+---------------+


File: manual.info,  Node: mysqlshow,  Next: mysqlslap,  Prev: mysqlimport,  Up: programs-client

4.5.6 `mysqlshow' -- Display Database, Table, and Column Information
--------------------------------------------------------------------

The `mysqlshow' client can be used to quickly see which databases
exist, their tables, or a table's columns or indexes.

`mysqlshow' provides a command-line interface to several SQL `SHOW'
statements. See *Note show::. The same information can be obtained by
using those statements directly. For example, you can issue them from
the `mysql' client program.

Invoke `mysqlshow' like this:

     shell> mysqlshow [OPTIONS] [DB_NAME [TBL_NAME [COL_NAME]]]

   * If no database is given, a list of database names is shown.

   * If no table is given, all matching tables in the database are
     shown.

   * If no column is given, all matching columns and column types in
     the table are shown.

The output displays only the names of those databases, tables, or
columns for which you have some privileges.

If the last argument contains shell or SQL wildcard characters (``*'',
``?'', ``%'', or ``_''), only those names that are matched by the
wildcard are shown. If a database name contains any underscores, those
should be escaped with a backslash (some Unix shells require two) to
get a list of the proper tables or columns. ``*'' and ``?'' characters
are converted into SQL ``%'' and ``_'' wildcard characters. This might
cause some confusion when you try to display the columns for a table
with a ``_'' in the name, because in this case, `mysqlshow' shows you
only the table names that match the pattern. This is easily fixed by
adding an extra ``%'' last on the command line as a separate argument.

*`mysqlshow' Option Reference*

*Format*       *Config File*  *Description*                        *Introduction*
-bind-address=host_name               Determine which client network       5.1.22-ndb-6.3.4
                              interface to use when connecting to  
                              the MySQL Server                     
-compress      compress       Compress all information sent        
                              between the client and the server    
-count         count          Show the number of rows per table    
-debug[=debug_options]debug          Write a debugging log                
-debug-check   debug-check    Print debugging information when     5.1.21
                              the program exits                    
-debug-info    debug-info     Print debugging information, memory  5.1.14
                              and CPU statistics when the          
                              program exits                        
-default-character-set=charset_namedefault-character-setUse charset_name as the default      
                              character set                        
-help                         Display help message and exit        
-host=host_namehost           Connect to the MySQL server on the   
                              given host                           
-keys          keys           Show table indexes                   
-password[=password]password       The password to use when connecting  
                              to the server                        
-pipe                         On Windows, connect to server via a  
                              named pipe                           
-port=port_num port           The TCP/IP port number to use for    
                              the connection                       
-protocol=type protocol       The connection protocol to use       
-show-table-type               Show a column indicating the table   
                              type                                 
-socket=path   socket         For connections to localhost         
-ssl-ca=file_namessl-ca         The path to a file that contains a   
                              list of trusted SSL CAs              
-ssl-capath=directory_namessl-capath     The path to a directory that         
                              contains trusted SSL CA              
                              certificates  in PEM format          
-ssl-cert=file_namessl-cert       The name of the SSL certificate      
                              file to use for establishing a       
                              secure connection                    
-ssl-cipher=cipher_listssl-cipher     A list of allowable ciphers to use   
                              for SSL encryption                   
-ssl-key=file_namessl-key        The name of the SSL key file to use  
                              for establishing a secure            
                              connection                           
-ssl-verify-server-certssl-verify-server-certThe server's Common Name value in    
                              its certificate is verified          
                              against the hostname used when       
                              connecting to the server             
-status        status         Display extra information about      
                              each table                           
-user=user_name,user           The MySQL username to use when       
                              connecting to the server             
-verbose                      Verbose mode                         
-version                      Display version information and exit 

`mysqlshow' supports the following options:

   *  `--help', `-?'

     Display a help message and exit.

   *  `--character-sets-dir=PATH'

     The directory where character sets are installed. See *Note
     charset-configuration::.

   *  `--compress', `-C'

     Compress all information sent between the client and the server if
     both support compression.

   *  `--count'

     Show the number of rows per table. This can be slow for
     non-`MyISAM' tables.

   *  `--debug[=DEBUG_OPTIONS]', `-# [DEBUG_OPTIONS]'

     Write a debugging log. The DEBUG_OPTIONS string often is
     `'d:t:o,FILE_NAME''.

   *  `--debug-check'

     Print some debugging information when the program exits.  This
     option was added in MySQL 5.1.21.

   *  `--debug-info'

     Print debugging information and memory and CPU usage statistics
     when the program exits. This option was added in MySQL 5.1.14.

   *  `--default-character-set=CHARSET_NAME'

     Use CHARSET_NAME as the default character set. See *Note
     charset-configuration::.

   *  `--host=HOST_NAME', `-h HOST_NAME'

     Connect to the MySQL server on the given host.

   *  `--keys', `-k'

     Show table indexes.

   *  `--password[=PASSWORD]', `-p[PASSWORD]'

     The password to use when connecting to the server. If you use the
     short option form (`-p'), you _cannot_ have a space between the
     option and the password. If you omit the PASSWORD value following
     the `--password' or `-p' option on the command line, you are
     prompted for one.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security::.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security::.

   *  `--pipe', `-W'

     On Windows, connect to the server via a named pipe. This option
     applies only for connections to a local server, and only if the
     server supports named-pipe connections.

   *  `--port=PORT_NUM', `-P PORT_NUM'

     The TCP/IP port number to use for the connection.

   *  `--protocol={TCP|SOCKET|PIPE|MEMORY}'

     The connection protocol to use for connecting to the server.  It
     is useful when the other connection parameters normally would
     cause a protocol to be used other than the one you want. For
     details on the allowable values, see *Note connecting::.

   *  `--show-table-type', `-t'

     Show a column indicating the table type, as in `SHOW FULL TABLES'.
     The type is `BASE TABLE' or `VIEW'.

   *  `--socket=PATH', `-S PATH'

     For connections to `localhost', the Unix socket file to use, or,
     on Windows, the name of the named pipe to use.

   *  `--ssl*'

     Options that begin with `--ssl' specify whether to connect to the
     server via SSL and indicate where to find SSL keys and
     certificates. See *Note ssl-options::.

   *  `--status', `-i'

     Display extra information about each table.

   *  `--user=USER_NAME', `-u USER_NAME'

     The MySQL username to use when connecting to the server.

   *  `--verbose', `-v'

     Verbose mode. Print more information about what the program does.
     This option can be used multiple times to increase the amount of
     information.

   *  `--version', `-V'

     Display version information and exit.


File: manual.info,  Node: mysqlslap,  Prev: mysqlshow,  Up: programs-client

4.5.7 `mysqlslap' -- Load Emulation Client
------------------------------------------

`mysqlslap' is a diagnostic program designed to emulate client load for
a MySQL server and to report the timing of each stage. It works as if
multiple clients are accessing the server. `mysqlslap' is available as
of MySQL 5.1.4.

Invoke `mysqlslap' like this:

     shell> mysqlslap [OPTIONS]

Some options such as `--create' or `--query' enable you to specify a
string containing an SQL statement or a file containing statements. If
you specify a file, by default it must contain one statement per line.
(That is, the implicit statement delimiter is the newline character.)
Use the `--delimiter' option to specify a different delimiter, which
enables you to specify statements that span multiple lines or place
multiple statements on a single line. You cannot include comments in a
file; `mysqlslap' does not understand them.

*`mysqlslap' Option Reference*

*Format*       *Config File*  *Description*                        *Introduction*
-auto-generate-sqlauto-generate-sqlGenerate SQL statements              
                              automatically when they are not      
                              supplied  in files or via command    
                              options                              
-auto-generate-sql-add-auto-incrementauto-generate-sql-add-auto-incrementAdd AUTO_INCREMENT column to         5.1.18
                              automatically generated tables       
-auto-generate-sql-execute-number=#auto-generate-sql-execute-numberSpecify how many queries to          5.1.18
                              generate automatically               
-auto-generate-sql-guid-primaryauto-generate-sql-guid-primaryAdd a GUID-based primary key to      5.1.18
                              automatically generated tables       
-auto-generate-sql-load-type=typeauto-generate-sql-load-typeSpecify how many queries to          5.1.16
                              generate automatically               
-auto-generate-sql-secondary-indexes=#auto-generate-sql-secondary-indexesSpecify how many secondary indexes   5.1.18
                              to add to automatically  generated   
                              tables                               
-auto-generate-sql-unique-query-number=#auto-generate-sql-unique-query-numberHow many different queries to        5.1.18
                              generate for automatic tests.        
-auto-generate-sql-unique-write-number=#auto-generate-sql-unique-write-numberHow many different queries to        5.1.18
                              generate for                         
                              -auto-generate-sql-write-number      
-auto-generate-sql-write-number=#auto-generate-sql-write-numberHow many row inserts to perform on   5.1.16
                              each thread                          
-commit=#      commit         How many statements to execute       5.1.21
                              before committing.                   
-compress      compress       Compress all information sent        
                              between the client and the server    
-concurrency=# concurrency    The number of clients to simulate    
                              when issuing the SELECT  statement   
-create=value  create         The file or string containing the    
                              statement to use for creating  the   
                              table                                
-create-schema=valuecreate-schema  The schema in which to run the tests 5.1.5
-csv=[file]    csv            Generate output in comma-separated   
                              values format                        
-debug[=debug_options]debug          Write a debugging log                
-debug-check   debug-check    Print debugging information when     5.1.21
                              the program exits                    
-debug-info    debug-info     Print debugging information, memory  5.1.21
                              and CPU statistics when the          
                              program exits                        
-delimiter=str delimiter      The delimiter to use in SQL          
                              statements                           
-detach=#      detach         Detach (close and reopen) each       5.1.21
                              connection after each N statements   
-engine=engine_nameengine         The storage engine to use for        
                              creating the table                   
-help                         Display help message and exit        
-host=host_namehost           Connect to the MySQL server on the   
                              given host                           
-iterations=#  iterations     The number of times to run the tests 
-lock-directory=pathlock-directory The directory to use for storing     5.1.5
                              locks                                
-number-char-cols=#number-char-colsThe number of VARCHAR columns to     
                              use if -auto-generate-sql is         
                              specified                            
-number-int-cols=#number-int-colsThe number of INT columns to use if  
                              -auto-generate-sql is  specified     
-number-of-queries=#number-of-queriesLimit each client to approximately   5.1.5
                              this number of queries               
-only-print    only-print     Do not connect to databases.         5.1.5
                              mysqlslap only prints what it would  
                              have done                            
-password[=password]password       The password to use when connecting  
                              to the server                        
-pipe                         On Windows, connect to server via a  
                              named pipe                           
-port=port_num port           The TCP/IP port number to use for    
                              the connection                       
-post-query=valuepost-query     The file or string containing the    5.1.18
                              statement to execute after the       
                              tests have completed                 
-post-system=strpost-system    The string to execute via system()   5.1.21
                              after the tests have completed       
-pre-query=valuepre-query      The file or string containing the    5.1.18
                              statement to execute before          
                              running the tests                    
-preserve-schemapreserve-schemaPreserve the schema from the         5.1.5
                              mysqlslap run                        
-pre-system=strpre-system     The string to execute via system()>  5.1.21
                              before running the tests             
-protocol=type protocol       The connection protocol to use       
-silent        silent         Silent mode                          
-slave         slave          Follow master locks for other        5.1.5
                              mysqlslap clients                    
-socket=path   socket         For connections to localhost         
-ssl-ca=file_namessl-ca         The path to a file that contains a   
                              list of trusted SSL CAs              
-ssl-capath=directory_namessl-capath     The path to a directory that         
                              contains trusted SSL CA              
                              certificates  in PEM format          
-ssl-cert=file_namessl-cert       The name of the SSL certificate      
                              file to use for establishing a       
                              secure connection                    
-ssl-cipher=cipher_listssl-cipher     A list of allowable ciphers to use   
                              for SSL encryption                   
-ssl-key=file_namessl-key        The name of the SSL key file to use  
                              for establishing a secure            
                              connection                           
-ssl-verify-server-certssl-verify-server-certThe server's Common Name value in    
                              its certificate is verified          
                              against the hostname used when       
                              connecting to the server             
-user=user_name,user           The MySQL username to use when       
                              connecting to the server             
-use-threads   use-threads    On Unix, the default is to use       5.1.6
                              fork() calls                         
-verbose                      Verbose mode                         
-version                      Display version information and exit 

`mysqlslap' supports the following options:

   *  `--help', `-?'

     Display a help message and exit.

   *  `--auto-generate-sql', `-a'

     Generate SQL statements automatically when they are not supplied
     in files or via command options.

   *  `--auto-generate-sql-add-autoincrement'

     Add an `AUTO_INCREMENT' column to automatically generated tables.
     This option was added in MySQL 5.1.18.

   *  `--auto-generate-sql-execute-number=N'

     Specify how many queries to generate automatically. This option
     was added in MySQL 5.1.18.

   *  `--auto-generate-sql-guid-primary'

     Add a GUID-based primary key to automatically generated tables.
     This option was added in MySQL 5.1.18.

   *  `--auto-generate-sql-load-type=TYPE'

     Specify the test load type. The allowable values are `read' (scan
     tables), `write' (insert into tables), `key' (read primary keys),
     `update' (update primary keys), or `mixed' (half inserts, half
     scanning selects). The default is `mixed'. This option was added
     in MySQL 5.1.16.

   *  `--auto-generate-sql-secondary-indexes=N'

     Specify how many secondary indexes to add to automatically
     generated tables. By default, none are added. This option was
     added in MySQL 5.1.18.

   *  `--auto-generate-sql-unique-query-number=N'

     How many different queries to generate for automatic tests.  For
     example, if you run a `key' test that performs 1000 selects, you
     can use this option with a value of 1000 to run 1000 unique
     queries, or with a value of 50 to perform 50 different selects.
     The default is 10. This option was added in MySQL 5.1.18.

   *  `--auto-generate-sql-unique-write-number=N'

     How many different queries to generate for
     `--auto-generate-sql-write-number'. The default is 10. This option
     was added in MySQL 5.1.18.

   *  `--auto-generate-sql-write-number=N'

     How many row inserts to perform on each thread. The default is
     100. This option was added in MySQL 5.1.16.

   *  `--commit=N'

     How many statements to execute before committing. The default is 0
     (no commits are done). This option was added in MySQL 5.1.21.

   *  `--compress', `-C'

     Compress all information sent between the client and the server if
     both support compression.

   *  `--concurrency=N', `-c N'

     The number of clients to simulate when issuing the `SELECT'
     statement.

   *  `--create=VALUE'

     The file or string containing the statement to use for creating
     the table.

   *  `--create-schema=VALUE'

     The schema in which to run the tests. This option was added in
     MySQL 5.1.5.

   *  `--csv[=FILE_NAME]'

     Generate output in comma-separated values format. The output goes
     to the named file, or to the standard output if no file is given.
     This option was added in MySQL 5.1.5.

   *  `--debug[=DEBUG_OPTIONS]', `-# [DEBUG_OPTIONS]'

     Write a debugging log. The DEBUG_OPTIONS string often is
     `'d:t:o,FILE_NAME''.

   *  `--debug-check'

     Print some debugging information when the program exits.  This
     option was added in MySQL 5.1.21.

   *  `--debug-info', `-T'

     Print debugging information and memory and CPU usage statistics
     when the program exits. This option was added in MySQL 5.1.21.

   *  `--delimiter=STR', `-F STR'

     The delimiter to use in SQL statements supplied in files or via
     command options.

   *  `--detach=N'

     Detach (close and reopen) each connection after each N statements.
     The default is 0 (connections are not detached). This option was
     added in MySQL 5.1.21.

   *  `--engine=ENGINE_NAME', `-e ENGINE_NAME'

     The storage engine to use for creating tables.

   *  `--host=HOST_NAME', `-h HOST_NAME'

     Connect to the MySQL server on the given host.

   *  `--iterations=N', `-i N'

     The number of times to run the tests.

   *  `--lock-directory=PATH'

     The directory to use for storing locks. This option was added in
     MySQL 5.1.5 and removed in 5.1.18.

   *  `--number-char-cols=N', `-x N'

     The number of `VARCHAR' columns to use if `--auto-generate-sql' is
     specified.

   *  `--number-int-cols=N', `-y N'

     The number of `INT' columns to use if `--auto-generate-sql' is
     specified.

   *  `--number-of-queries=N'

     Limit each client to approximately this number of queries.  This
     option was added in MySQL 5.1.5.

   *  `--only-print'

     Do not connect to databases. `mysqlslap' only prints what it would
     have done. This option was added in MySQL 5.1.5.

   *  `--password[=PASSWORD]', `-p[PASSWORD]'

     The password to use when connecting to the server. If you use the
     short option form (`-p'), you _cannot_ have a space between the
     option and the password. If you omit the PASSWORD value following
     the

     `--password' or `-p' option on the command line, you are prompted
     for one.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security::.

   *  `--pipe', `-W'

     On Windows, connect to the server via a named pipe. This option
     applies only for connections to a local server, and only if the
     server supports named-pipe connections.

   *  `--port=PORT_NUM', `-P PORT_NUM'

     The TCP/IP port number to use for the connection.

   *  `--post-query=VALUE'

     The file or string containing the statement to execute after the
     tests have completed. This execution is not counted for timing
     purposes. This option was added in MySQL 5.1.18.

   *  `--post-system=STR'

     The string to execute via `system()' after the tests have
     completed. This execution is not counted for timing purposes. This
     option was added in MySQL 5.1.21.

   *  `--pre-query=VALUE'

     The file or string containing the statement to execute before
     running the tests. This execution is not counted for timing
     purposes. This option was added in MySQL 5.1.18.

   *  `--pre-system=STR'

     The string to execute via `system()' before running the tests.
     This execution is not counted for timing purposes. This option was
     added in MySQL 5.1.21.

   *  `--preserve-schema'

     Preserve the schema from the `mysqlslap' run. The
     `--auto-generate-sql' and `--create' options disable this option.
     This option was added in MySQL 5.1.5.

   *  `--protocol={TCP|SOCKET|PIPE|MEMORY}'

     The connection protocol to use for connecting to the server.  It
     is useful when the other connection parameters normally would
     cause a protocol to be used other than the one you want. For
     details on the allowable values, see *Note connecting::.

   *  `--query=VALUE', `-q VALUE'

     The file or string containing the `SELECT' statement to use for
     retrieving data.

   *  `--silent', `-s'

     Silent mode. No output.

   *  `--slave'

     Follow master locks for other `mysqlslap' clients. Use this option
     if you are trying to synchronize around one master server with
     `--lock-directory' plus NFS. This option was added in MySQL 5.1.5
     and removed in 5.1.18.

   *  `--socket=PATH', `-S PATH'

     For connections to `localhost', the Unix socket file to use, or,
     on Windows, the name of the named pipe to use.

   *  `--ssl*'

     Options that begin with `--ssl' specify whether to connect to the
     server via SSL and indicate where to find SSL keys and
     certificates. See *Note ssl-options::.

   *  `--use-threads'

     On Unix, the default is to use `fork()' calls and this option
     causes `pthread' calls to be used instead. (On Windows, the
     default is to use `pthread' calls and the option has no effect.)
     This option was added in MySQL 5.1.6 and removed in 5.1.18.

   *  `--user=USER_NAME', `-u USER_NAME'

     The MySQL username to use when connecting to the server.

   *  `--verbose', `-v'

     Verbose mode. Print more information about what the program does.
     This option can be used multiple times to increase the amount of
     information.

   *  `--version', `-V'

     Display version information and exit.


File: manual.info,  Node: programs-admin-utils,  Next: programs-development,  Prev: programs-client,  Up: programs

4.6 MySQL Administrative and Utility Programs
=============================================

* Menu:

* innochecksum::                 `innochecksum' --- Offline InnoDB File Checksum Utility
* myisam-ftdump::                `myisam_ftdump' --- Display Full-Text Index information
* myisamchk::                    `myisamchk' --- MyISAM Table-Maintenance Utility
* myisamlog::                    `myisamlog' --- Display MyISAM Log File Contents
* myisampack::                   `myisampack' --- Generate Compressed, Read-Only MyISAM Tables
* mysqlaccess::                  `mysqlaccess' --- Client for Checking Access Privileges
* mysqlbinlog::                  `mysqlbinlog' --- Utility for Processing Binary Log Files
* mysqlhotcopy::                 `mysqlhotcopy' --- A Database Backup Program
* instance-manager::             `mysqlmanager' --- The MySQL Instance Manager
* mysql-convert-table-format::   `mysql_convert_table_format' --- Convert Tables to Use a Given Storage Engine
* mysql-find-rows::              `mysql_find_rows' --- Extract SQL Statements from Files
* mysql-fix-extensions::         `mysql_fix_extensions' --- Normalize Table Filename Extensions
* mysql-setpermission::          `mysql_setpermission' --- Interactively Set Permissions in Grant Tables
* mysql-waitpid::                `mysql_waitpid' --- Kill Process and Wait for Its Termination
* mysql-zap::                    `mysql_zap' --- Kill Processes That Match a Pattern


File: manual.info,  Node: innochecksum,  Next: myisam-ftdump,  Prev: programs-admin-utils,  Up: programs-admin-utils

4.6.1 `innochecksum' -- Offline InnoDB File Checksum Utility
------------------------------------------------------------

`innochecksum' prints checksums for `InnoDB' files.

Invoke `innochecksum' like this:

     shell> innochecksum [OPTIONS] FILE_NAME

`innochecksum' understands the options described in the following list.
For options that refer to page numbers, the numbers are zero-based.

   *  `-c'

     Print a count of the number of pages in the file.

   *  `-d'

     Debug mode; prints checksums for each page.

   *  `-e NUM'

     End at this page number.

   *  `-p NUM'

     Check only this page number.

   *  `-s NUM'

     Start at this page number.

   *  `-v'

     Verbose mode; print a progress indicator every five seconds.


File: manual.info,  Node: myisam-ftdump,  Next: myisamchk,  Prev: innochecksum,  Up: programs-admin-utils

4.6.2 `myisam_ftdump' -- Display Full-Text Index information
------------------------------------------------------------

`myisam_ftdump' displays information about `FULLTEXT' indexes in
`MyISAM' tables. It reads the `MyISAM' index file directly, so it must
be run on the server host where the table is located

Invoke `myisam_ftdump' like this:

     shell> myisam_ftdump [OPTIONS] TBL_NAME INDEX_NUM

The TBL_NAME argument should be the name of a `MyISAM' table. You can
also specify a table by naming its index file (the file with the `.MYI'
suffix). If you do not invoke `myisam_ftdump' in the directory where the
table files are located, the table or index file name must be preceded
by the pathname to the table's database directory.  Index numbers begin
with 0.

Example: Suppose that the `test' database contains a table named
`mytexttablel' that has the following definition:

     CREATE TABLE mytexttable
     (
       id   INT NOT NULL,
       txt  TEXT NOT NULL,
       PRIMARY KEY (id),
       FULLTEXT (txt)
     );

The index on `id' is index 0 and the `FULLTEXT' index on `txt' is index
1. If your working directory is the `test' database directory, invoke
`myisam_ftdump' as follows:

     shell> myisam_ftdump mytexttable 1

If the pathname to the `test' database directory is
`/usr/local/mysql/data/test', you can also specify the table name
argument using that pathname. This is useful if you do not invoke
`myisam_ftdump' in the database directory:

     shell> myisam_ftdump /usr/local/mysql/data/test/mytexttable 1

`myisam_ftdump' understands the following options:

   *  `--help', `-h' `-?'

     Display a help message and exit.

   *  `--count', `-c'

     Calculate per-word statistics (counts and global weights).

   *  `--dump', `-d'

     Dump the index, including data offsets and word weights.

   *  `--length', `-l'

     Report the length distribution.

   *  `--stats', `-s'

     Report global index statistics. This is the default operation if
     no other operation is specified.

   *  `--verbose', `-v'

     Verbose mode. Print more output about what the program does.


File: manual.info,  Node: myisamchk,  Next: myisamlog,  Prev: myisam-ftdump,  Up: programs-admin-utils

4.6.3 `myisamchk' -- MyISAM Table-Maintenance Utility
-----------------------------------------------------

* Menu:

* myisamchk-general-options::    `myisamchk' General Options
* myisamchk-check-options::      `myisamchk' Check Options
* myisamchk-repair-options::     `myisamchk' Repair Options
* myisamchk-other-options::      Other `myisamchk' Options
* myisamchk-memory::             `myisamchk' Memory Usage

The `myisamchk' utility gets information about your database tables or
checks, repairs, or optimizes them.  `myisamchk' works with `MyISAM'
tables (tables that have `.MYD' and `.MYI' files for storing data and
indexes).

The use of `myisamchk' with partitioned tables is not supported.

*Caution*:

It is best to make a backup of a table before performing a table repair
operation; under some circumstances the operation might cause data
loss. Possible causes include but are not limited to filesystem errors.

Invoke `myisamchk' like this:

     shell> myisamchk [OPTIONS] TBL_NAME ...

The OPTIONS specify what you want `myisamchk' to do. They are described
in the following sections. You can also get a list of options by
invoking `myisamchk --help'.

With no options, `myisamchk' simply checks your table as the default
operation. To get more information or to tell `myisamchk' to take
corrective action, specify options as described in the following
discussion.

TBL_NAME is the database table you want to check or repair. If you run
`myisamchk' somewhere other than in the database directory, you must
specify the path to the database directory, because `myisamchk' has no
idea where the database is located. In fact, `myisamchk' doesn't
actually care whether the files you are working on are located in a
database directory. You can copy the files that correspond to a
database table into some other location and perform recovery operations
on them there.

You can name several tables on the `myisamchk' command line if you
wish. You can also specify a table by naming its index file (the file
with the `.MYI' suffix). This allows you to specify all tables in a
directory by using the pattern `*.MYI'. For example, if you are in a
database directory, you can check all the `MyISAM' tables in that
directory like this:

     shell> myisamchk *.MYI

If you are not in the database directory, you can check all the tables
there by specifying the path to the directory:

     shell> myisamchk /PATH/TO/DATABASE_DIR/*.MYI

You can even check all tables in all databases by specifying a wildcard
with the path to the MySQL data directory:

     shell> myisamchk /PATH/TO/DATADIR/*/*.MYI

The recommended way to quickly check all `MyISAM' tables is:

     shell> myisamchk --silent --fast /PATH/TO/DATADIR/*/*.MYI

If you want to check all `MyISAM' tables and repair any that are
corrupted, you can use the following command:

     shell> myisamchk --silent --force --fast --update-state \
               --key_buffer_size=64M --sort_buffer_size=64M \
               --read_buffer_size=1M --write_buffer_size=1M \
               /PATH/TO/DATADIR/*/*.MYI

This command assumes that you have more than 64MB free. For more
information about memory allocation with `myisamchk', see *Note
myisamchk-memory::.

MySQL Enterprise

For expert advice on checking and repairing tables, subscribe to the
MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

*Important*:

_You must ensure that no other program is using the tables while you
are running `myisamchk'_. The most effective means of doing so is to
shut down the MySQL server while running `myisamchk', or to lock all
tables that `myisamchk' is being used on.

Otherwise, when you run `myisamchk', it may display the following error
message:

     warning: clients are using or haven't closed the table properly

This means that you are trying to check a table that has been updated
by another program (such as the `mysqld' server) that hasn't yet closed
the file or that has died without closing the file properly, which can
sometimes lead to the corruption of one or more `MyISAM' tables.

If `mysqld' is running, you must force it to flush any table
modifications that are still buffered in memory by using `FLUSH
TABLES'. You should then ensure that no one is using the tables while
you are running `myisamchk'

However, the easiest way to avoid this problem is to use `CHECK TABLE'
instead of `myisamchk' to check tables. See *Note check-table::.

A complete listing of all the `myisamchk' options follows.

*`myisamchk' Option Reference*

*Format*       *Config File*  *Description*                        *Introduction*
-analyze       analyze        Analyze the distribution of key      
                              values                               
-backup        backup         Make a backup of the .MYD file as    
                              file_name-time.BAK                   
-block-search=offsetblock-search   Find the record that a block at the  
                              given offset belongs to              
-check         check          Check the table for errors           
-check-only-changedcheck-only-changedCheck only tables that have changed  
                              since the last check                 
-correct-checksumcorrect-checksumCorrect the checksum information     
                              for the table                        
-data-file-length=lendata-file-lengthMaximum length of the data file      
                              (when re-creating data file when     
                              it is full)                          
-debug[=debug_options]debug          Write a debugging log                
decode_bits=#  decode_bits    Decode_bits                          
-description   description    Print some descriptive information   
                              about the table                      
-extend-check  extend-check   Do a repair that tries to recover    
                              every possible row from the data     
                              file                                 
-extended-checkextended-check Check the table very thoroughly      
-fast          fast           Check only tables that haven't been  
                              closed properly                      
-force         force          Do a repair operation automatically  
                              if myisamchk finds any errors  in    
                              the table                            
-force         force-recover  Overwrite old temporary files. For   
                              use with the -r or -o option         
ft_max_word_len=#ft_max_word_lenMaximum word length for FULLTEXT     
                              indexes                              
ft_min_word_len=#ft_min_word_lenMinimum word length for FULLTEXT     
                              indexes                              
ft_stopword_file=valueft_stopword_fileUse stopwords from this file         
                              instead of built-in list             
-help                         Display help message and exit        
-information   information    Print informational statistics       
                              about the table that is checked      
key_buffer_size=#key_buffer_sizeThe size of the buffer used for      
                              index blocks for MyISAM tables       
-keys-used=val keys-used      A bit-value that indicates which     
                              indexes to update                    
-max-record-length=lenmax-record-lengthSkip rows larger than the given      
                              length if myisamchk cannot           
                              allocate memory to hold them         
-medium-check  medium-check   Do a check that is faster than an    
                              -extend-check operation              
myisam_block_size=#myisam_block_sizeBlock size to be used for MyISAM     
                              index pages                          
-parallel-recoverparallel-recoverUses the same technique as -r and    
                              -n, but creates all the keys in      
                              parallel, using different threads    
                              (beta)                               
-quick         quick          Achieve a faster repair by not       
                              modifying the data file.             
read_buffer_size=#read_buffer_sizeEach thread that does a sequential   
                              scan allocates a buffer of this      
                              size for each table it scans         
-read-only     read-only      Don't mark the table as checked      
-recover       recover        Do a repair that can fix almost any  
                              problem except unique keys  that     
                              aren't unique                        
-safe-recover  safe-recover   Do a repair using an old recovery    
                              method that reads through all  rows  
                              in order and updates all index       
                              trees based on the rows found        
-set-auto-increment[=value]set-auto-incrementForce AUTO_INCREMENT numbering for   
                              new records to start at the  given   
                              value                                
-set-collation=nameset-collation  Specify the collation to use for     
                              sorting table indexes                
-silent        silent         Silent mode                          
sort_buffer_size=#sort_buffer_sizeThe buffer that is allocated when    
                              sorting the index when doing a       
                              REPAIR or when creating indexes      
                              with CREATE INDEX or ALTER TABLE     
-sort-index    sort-index     Sort the index tree blocks in        
                              high-low order                       
sort_key_blocks=#sort_key_blockssort_key_blocks                      
-sort-records=#sort-records   Sort records according to a          
                              particular index                     
-sort-recover  sort-recover   Force myisamchk to use sorting to    
                              resolve the keys even if the         
                              temporary files would be very large  
stats_method=valuestats_method   Specifies how MyISAM index           
                              statistics collection code should    
                              treat  NULLs                         
-tmpdir=path   tmpdir         Path of the directory to be used     
                              for storing temporary files          
-unpack        unpack         Unpack a table that was packed with  
                              myisampack                           
-update-state  update-state   Store information in the .MYI file   
                              to indicate when the table was       
                              checked and whether the table        
                              crashed                              
-verbose                      Verbose mode                         
-version                      Display version information and exit 
write_buffer_size=#write_buffer_sizeWrite buffer size                    


File: manual.info,  Node: myisamchk-general-options,  Next: myisamchk-check-options,  Prev: myisamchk,  Up: myisamchk

4.6.3.1 `myisamchk' General Options
...................................

The options described in this section can be used for any type of table
maintenance operation performed by `myisamchk'. The sections following
this one describe options that pertain only to specific operations, such
as table checking or repairing.

   *  `--help', `-?'

     Display a help message and exit.

   *  `--debug=DEBUG_OPTIONS, -# DEBUG_OPTIONS'

     Write a debugging log. The DEBUG_OPTIONS string often is
     `'d:t:o,FILE_NAME''.

   *  `--silent', `-s'

     Silent mode. Write output only when errors occur. You can use `-s'
     twice (`-ss') to make `myisamchk' very silent.

   *  `--verbose', `-v'

     Verbose mode. Print more information about what the program does.
     This can be used with `-d' and `-e'. Use `-v' multiple times
     (`-vv', `-vvv') for even more output.

   *  `--version', `-V'

     Display version information and exit.

   *  `--wait', `-w'

     Instead of terminating with an error if the table is locked, wait
     until the table is unlocked before continuing. If you are running
     `mysqld' with external locking disabled, the table can be locked
     only by another `myisamchk' command.

You can also set the following variables by using `--VAR_NAME=VALUE'
syntax:

*Variable*                *Default Value*
`decode_bits'             9
`ft_max_word_len'         version-dependent
`ft_min_word_len'         4
`ft_stopword_file'        built-in list
`key_buffer_size'         523264
`myisam_block_size'       1024
`read_buffer_size'        262136
`sort_buffer_size'        2097144
`sort_key_blocks'         16
`stats_method'            nulls_unequal
`write_buffer_size'       262136

The possible `myisamchk' variables and their default values can be
examined with `myisamchk --help':

`sort_buffer_size' is used when the keys are repaired by sorting keys,
which is the normal case when you use `--recover'.

`key_buffer_size' is used when you are checking the table with
`--extend-check' or when the keys are repaired by inserting keys row by
row into the table (like when doing normal inserts). Repairing through
the key buffer is used in the following cases:

   * You use `--safe-recover'.

   * The temporary files needed to sort the keys would be more than
     twice as big as when creating the key file directly.  This is
     often the case when you have large key values for `CHAR',
     `VARCHAR', or `TEXT' columns, because the sort operation needs to
     store the complete key values as it proceeds. If you have lots of
     temporary space and you can force `myisamchk' to repair by
     sorting, you can use the `--sort-recover' option.

Repairing through the key buffer takes much less disk space than using
sorting, but is also much slower.

If you want a faster repair, set the `key_buffer_size' and
`sort_buffer_size' variables to about 25% of your available memory. You
can set both variables to large values, because only one of them is
used at a time.

`myisam_block_size' is the size used for index blocks.

`stats_method' influences how `NULL' values are treated for index
statistics collection when the `--analyze' option is given.  It acts
like the `myisam_stats_method' system variable. For more information,
see the description of `myisam_stats_method' in *Note
server-system-variables::, and *Note myisam-index-statistics::. For
MySQL 5.1, `stats_method' was added in MySQL 5.0.14. For older
versions, the statistics collection method is equivalent to
`nulls_equal'.

The `ft_min_word_len' and `ft_max_word_len' variables are available as
of MySQL 4.0.0. `ft_stopword_file' is available as of MySQL 4.0.19.

`ft_min_word_len' and `ft_max_word_len' indicate the minimum and
maximum word length for `FULLTEXT' indexes.  `ft_stopword_file' names
the stopword file.  These need to be set under the following
circumstances.

If you use `myisamchk' to perform an operation that modifies table
indexes (such as repair or analyze), the `FULLTEXT' indexes are rebuilt
using the default full-text parameter values for minimum and maximum
word length and the stopword file unless you specify otherwise. This
can result in queries failing.

The problem occurs because these parameters are known only by the
server. They are not stored in `MyISAM' index files. To avoid the
problem if you have modified the minimum or maximum word length or the
stopword file in the server, specify the same `ft_min_word_len',
`ft_max_word_len', and `ft_stopword_file' values to `myisamchk' that
you use for `mysqld'. For example, if you have set the minimum word
length to 3, you can repair a table with `myisamchk' like this:

     shell> myisamchk --recover --ft_min_word_len=3 TBL_NAME.MYI

To ensure that `myisamchk' and the server use the same values for
full-text parameters, you can place each one in both the `[mysqld]' and
`[myisamchk]' sections of an option file:

     [mysqld]
     ft_min_word_len=3

     [myisamchk]
     ft_min_word_len=3

An alternative to using `myisamchk' is to use the `REPAIR TABLE',
`ANALYZE TABLE', `OPTIMIZE TABLE', or `ALTER TABLE'. These statements
are performed by the server, which knows the proper full-text parameter
values to use.


File: manual.info,  Node: myisamchk-check-options,  Next: myisamchk-repair-options,  Prev: myisamchk-general-options,  Up: myisamchk

4.6.3.2 `myisamchk' Check Options
.................................

`myisamchk' supports the following options for table checking
operations:

   *  `--check', `-c'

     Check the table for errors. This is the default operation if you
     specify no option that selects an operation type explicitly.

   *  `--check-only-changed', `-C'

     Check only tables that have changed since the last check.

   *  `--extend-check', `-e'

     Check the table very thoroughly. This is quite slow if the table
     has many indexes. This option should only be used in extreme
     cases. Normally, `myisamchk' or `myisamchk --medium-check' should
     be able to determine whether there are any errors in the table.

     If you are using `--extend-check' and have plenty of memory,
     setting the `key_buffer_size' variable to a large value helps the
     repair operation run faster.

   *  `--fast', `-F'

     Check only tables that haven't been closed properly.

   *  `--force', `-f'

     Do a repair operation automatically if `myisamchk' finds any
     errors in the table.  The repair type is the same as that
     specified with the `--recover' or `-r' option.

   *  `--information', `-i'

     Print informational statistics about the table that is checked.

   *  `--medium-check', `-m'

     Do a check that is faster than an `--extend-check' operation. This
     finds only 99.99% of all errors, which should be good enough in
     most cases.

   *  `--read-only', `-T'

     Don't mark the table as checked. This is useful if you use
     `myisamchk' to check a table that is in use by some other
     application that doesn't use locking, such as `mysqld' when run
     with external locking disabled.

   *  `--update-state', `-U'

     Store information in the `.MYI' file to indicate when the table
     was checked and whether the table crashed. This should be used to
     get full benefit of the `--check-only-changed' option, but you
     shouldn't use this option if the `mysqld' server is using the
     table and you are running it with external locking disabled.


File: manual.info,  Node: myisamchk-repair-options,  Next: myisamchk-other-options,  Prev: myisamchk-check-options,  Up: myisamchk

4.6.3.3 `myisamchk' Repair Options
..................................

`myisamchk' supports the following options for table repair operations:

   *  `--backup', `-B'

     Make a backup of the `.MYD' file as `FILE_NAME-TIME.BAK'

   *  `--character-sets-dir=PATH'

     The directory where character sets are installed. See *Note
     charset-configuration::.

   *  `--correct-checksum'

     Correct the checksum information for the table.

   *  `--data-file-length=LEN, -D LEN'

     Maximum length of the data file (when re-creating data file when
     it is `full').

   *  `--extend-check', `-e'

     Do a repair that tries to recover every possible row from the data
     file. Normally, this also finds a lot of garbage rows. Don't use
     this option unless you are desperate.

   * `--force', `-f'

     Overwrite old intermediate files (files with names like
     `TBL_NAME.TMD') instead of aborting.

   *  `--keys-used=VAL', `-k VAL'

     For `myisamchk', the option value is a bit-value that indicates
     which indexes to update. Each binary bit of the option value
     corresponds to a table index, where the first index is bit 0. An
     option value of 0 disables updates to all indexes, which can be
     used to get faster inserts. Deactivated indexes can be reactivated
     by using `myisamchk -r'.

   *  `--no-symlinks', `-l'

     Do not follow symbolic links. Normally `myisamchk' repairs the
     table that a symlink points to. This option does not exist as of
     MySQL 4.0 because versions from 4.0 on do not remove symlinks
     during repair operations.

   *  `--max-record-length=LEN'

     Skip rows larger than the given length if `myisamchk' cannot
     allocate memory to hold them.

   *  `--parallel-recover', `-p'

     Uses the same technique as `-r' and `-n', but creates all the keys
     in parallel, using different threads. _This is beta-quality code.
     Use at your own risk!_

   *  `--quick', `-q'

     Achieve a faster repair by not modifying the data file. You can
     specify this option twice to force `myisamchk' to modify the
     original data file in case of duplicate keys.

   *  `--recover', `-r'

     Do a repair that can fix almost any problem except unique keys
     that aren't unique (which is an extremely unlikely error with
     `MyISAM' tables). If you want to recover a table, this is the
     option to try first. You should try `--safe-recover' only if
     `myisamchk' reports that the table can't be recovered using
     `--recover'. (In the unlikely case that `--recover' fails, the
     data file remains intact.)

     If you have lots of memory, you should increase the value of
     `sort_buffer_size'.

   *  `--safe-recover', `-o'

     Do a repair using an old recovery method that reads through all
     rows in order and updates all index trees based on the rows found.
     This is an order of magnitude slower than `--recover', but can
     handle a couple of very unlikely cases that `--recover' cannot.
     This recovery method also uses much less disk space than
     `--recover'. Normally, you should repair first with `--recover',
     and then with `--safe-recover' only if `--recover' fails.

     If you have lots of memory, you should increase the value of
     `key_buffer_size'.

   *  `--set-character-set=NAME'

     Change the character set used by the table indexes. This option
     was replaced by `--set-collation' in MySQL 5.0.3.

   *  `--set-collation=NAME'

     Specify the collation to use for sorting table indexes. The
     character set name is implied by the first part of the collation
     name.

   *  `--sort-recover', `-n'

     Force `myisamchk' to use sorting to resolve the keys even if the
     temporary files would be very large.

   *  `--tmpdir=PATH', `-t PATH'

     Path of the directory to be used for storing temporary files. If
     this is not set, `myisamchk' uses the value of the `TMPDIR'
     environment variable. `tmpdir' can be set to a list of directory
     paths that are used successively in round-robin fashion for
     creating temporary files. The separator character between
     directory names is the colon (``:'') on Unix and the semicolon
     (``;'') on Windows, NetWare, and OS/2.

   *  `--unpack', `-u'

     Unpack a table that was packed with `myisampack'.


File: manual.info,  Node: myisamchk-other-options,  Next: myisamchk-memory,  Prev: myisamchk-repair-options,  Up: myisamchk

4.6.3.4 Other `myisamchk' Options
.................................

`myisamchk' supports the following options for actions other than table
checks and repairs:

   *  `--analyze', `-a'

     Analyze the distribution of key values. This improves join
     performance by enabling the join optimizer to better choose the
     order in which to join the tables and which indexes it should use.
     To obtain information about the key distribution, use a `myisamchk
     --description --verbose TBL_NAME' command or the `SHOW INDEX FROM
     TBL_NAME' statement.

     MySQL Enterprise

     For expert advice on optimizing tables, subscribe to the MySQL
     Enterprise Monitor. For more information, see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   *  `--block-search=OFFSET', `-b OFFSET'

     Find the record that a block at the given offset belongs to.

   *  `--description', `-d'

     Print some descriptive information about the table.

   *  `--set-auto-increment[=VALUE]', `-A[VALUE]'

     Force `AUTO_INCREMENT' numbering for new records to start at the
     given value (or higher, if there are existing records with
     `AUTO_INCREMENT' values this large). If VALUE is not specified,
     `AUTO_INCREMENT' numbers for new records begin with the largest
     value currently in the table, plus one.

   *  `--sort-index', `-S'

     Sort the index tree blocks in high-low order. This optimizes seeks
     and makes table scans that use indexes faster.

   *  `--sort-records=N', `-R N'

     Sort records according to a particular index. This makes your data
     much more localized and may speed up range-based `SELECT' and
     `ORDER BY' operations that use this index. (The first time you use
     this option to sort a table, it may be very slow.) To determine a
     table's index numbers, use `SHOW INDEX', which displays a table's
     indexes in the same order that `myisamchk' sees them. Indexes are
     numbered beginning with 1.

     If keys are not packed (`PACK_KEYS=0'), they have the same length,
     so when `myisamchk' sorts and moves records, it just overwrites
     record offsets in the index. If keys are packed (`PACK_KEYS=1'),
     `myisamchk' must unpack key blocks first, then re-create indexes
     and pack the key blocks again. (In this case, re-creating indexes
     is faster than updating offsets for each index.)


File: manual.info,  Node: myisamchk-memory,  Prev: myisamchk-other-options,  Up: myisamchk

4.6.3.5 `myisamchk' Memory Usage
................................

Memory allocation is important when you run `myisamchk'. `myisamchk'
uses no more memory than its memory-related variables are set to. If
you are going to use `myisamchk' on very large tables, you should first
decide how much memory you want it to use. The default is to use only
about 3MB to perform repairs. By using larger values, you can get
`myisamchk' to operate faster. For example, if you have more than 32MB
RAM, you could use options such as these (in addition to any other
options you might specify):

     shell> myisamchk --sort_buffer_size=16M --key_buffer_size=16M \
                --read_buffer_size=1M --write_buffer_size=1M ...

Using `--sort_buffer_size=16M' should probably be enough for most cases.

Be aware that `myisamchk' uses temporary files in `TMPDIR'. If `TMPDIR'
points to a memory filesystem, you may easily get out of memory errors.
If this happens, run `myisamchk' with the `--tmpdir=PATH' option to
specify some directory located on a filesystem that has more space.

When repairing, `myisamchk' also needs a lot of disk space:

   * Double the size of the data file (the original file and a copy).
     This space is not needed if you do a repair with `--quick'; in
     this case, only the index file is re-created. This space is needed
     on the same filesystem as the original data file! (The copy is
     created in the same directory as the original.)

   * Space for the new index file that replaces the old one. The old
     index file is truncated at the start of the repair operation, so
     you usually ignore this space. This space is needed on the same
     filesystem as the original index file!

   * When using `--recover' or `--sort-recover' (but not when using
     `--safe-recover'), you need space for a sort buffer. The following
     formula yields the amount of space required:

          (LARGEST_KEY + ROW_POINTER_LENGTH) x NUMBER_OF_ROWS x 2

     You can check the length of the keys and the `row_pointer_length'
     with `myisamchk -dv TBL_NAME'. This space is allocated in the
     temporary directory (specified by `TMPDIR' or `--tmpdir=PATH').

If you have a problem with disk space during repair, you can try
`--safe-recover' instead of `--recover'.


File: manual.info,  Node: myisamlog,  Next: myisampack,  Prev: myisamchk,  Up: programs-admin-utils

4.6.4 `myisamlog' -- Display MyISAM Log File Contents
-----------------------------------------------------

`myisamlog' processes the contents of a `MyISAM' log file.

Invoke `myisamlog' like this:

     shell> myisamlog [OPTIONS] [LOG_FILE [TBL_NAME] ...]
     shell> isamlog [OPTIONS] [LOG_FILE [TBL_NAME] ...]

The default operation is update (`-u'). If a recovery is done (`-r'),
all writes and possibly updates and deletes are done and errors are
only counted. The default log file name is `myisam.log' for `myisamlog'
and `isam.log' for `isamlog' if no LOG_FILE argument is given, If tables
are named on the command line, only those tables are updated.

`myisamlog' understands the following options:

   *  `-?', `-I'

     Display a help message and exit.

   * `-c N'

     Execute only N commands.

   *  `-f N'

     Specify the maximum number of open files.

   *  `-i'

     Display extra information before exiting.

   *  `-o OFFSET'

     Specify the starting offset.

   *  `-p N'

     Remove N components from path.

   *  `-r'

     Perform a recovery operation.

   *  `-R RECORD_POS_FILE RECORD_POS'

     Specify record position file and record position.

   *  `-u'

     Perform an update operation.

   *  `-v'

     Verbose mode. Print more output about what the program does.  This
     option can be given multiple times to produce more and more output.

   *  `-w WRITE_FILE'

     Specify the write file.

   *  `-V'

     Display version information.


File: manual.info,  Node: myisampack,  Next: mysqlaccess,  Prev: myisamlog,  Up: programs-admin-utils

4.6.5 `myisampack' -- Generate Compressed, Read-Only MyISAM Tables
------------------------------------------------------------------

The `myisampack' utility compresses `MyISAM' tables. `myisampack' works
by compressing each column in the table separately.  Usually,
`myisampack' packs the data file 40%-70%.

When the table is used later, the server reads into memory the
information needed to decompress columns. This results in much better
performance when accessing individual rows, because you only have to
uncompress exactly one row.

MySQL uses `mmap()' when possible to perform memory mapping on
compressed tables. If `mmap()' does not work, MySQL falls back to
normal read/write file operations.

Please note the following:

   * If the `mysqld' server was invoked with external locking disabled,
     it is not a good idea to invoke `myisampack' if the table might be
     updated by the server during the packing process. It is safest to
     compress tables with the server stopped.

   * After packing a table, it becomes read only. This is generally
     intended (such as when accessing packed tables on a CD). Allowing
     writes to a packed table is on our TODO list, but with low
     priority.

Invoke `myisampack' like this:

     shell> myisampack [OPTIONS] FILE_NAME ...

Each filename argument should be the name of an index (`.MYI') file. If
you are not in the database directory, you should specify the pathname
to the file. It is permissible to omit the `.MYI' extension.

After you compress a table with `myisampack', you should use `myisamchk
-rq' to rebuild its indexes. *Note myisamchk::.

`myisampack' supports the following options:

   *  `--help', `-?'

     Display a help message and exit.

   *  `--backup', `-b'

     Make a backup of each table's data file using the name
     `TBL_NAME.OLD'.

   *  `--character-sets-dir=PATH'

     The directory where character sets are installed. See *Note
     charset-configuration::.

   *  `--debug[=DEBUG_OPTIONS]', `-# [DEBUG_OPTIONS]'

     Write a debugging log. The DEBUG_OPTIONS string often is
     `'d:t:o,FILE_NAME''.

   *  `--force', `-f'

     Produce a packed table even if it becomes larger than the original
     or if the intermediate file from an earlier invocation of
     `myisampack' exists.  (`myisampack' creates an intermediate file
     named `TBL_NAME.TMD' in the database directory while it compresses
     the table. If you kill `myisampack', the `.TMD' file might not be
     deleted.)  Normally, `myisampack' exits with an error if it finds
     that `TBL_NAME.TMD' exists. With `--force', `myisampack' packs the
     table anyway.

   *  `--join=BIG_TBL_NAME', `-j BIG_TBL_NAME'

     Join all tables named on the command line into a single packed
     table BIG_TBL_NAME. All tables that are to be combined _must_ have
     identical structure (same column names and types, same indexes,
     and so forth).

     BIG_TBL_NAME must not exist prior to the join operation. All
     source tables named on the command line to be merged into
     BIG_TBL_NAME must exist. The source tables are read for the join
     operation but not modified. The join operation does not create a
     `.frm' file for BIG_TBL_NAME, so after the join operation
     finishes, copy the `.frm' file from one of the source tables and
     name it `BIG_TBL_NAME.frm'.

   *  `--silent', `-s'

     Silent mode. Write output only when errors occur.

   *  `--test', `-t'

     Do not actually pack the table, just test packing it.

   *  `--tmpdir=PATH', `-T PATH'

     Use the named directory as the location where `myisampack' creates
     temporary files.

   *  `--verbose', `-v'

     Verbose mode. Write information about the progress of the packing
     operation and its result.

   *  `--version', `-V'

     Display version information and exit.

   *  `--wait', `-w'

     Wait and retry if the table is in use. If the `mysqld' server was
     invoked with external locking disabled, it is not a good idea to
     invoke `myisampack' if the table might be updated by the server
     during the packing process.

The following sequence of commands illustrates a typical table
compression session:

     shell> ls -l station.*
     -rw-rw-r--   1 monty    my         994128 Apr 17 19:00 station.MYD
     -rw-rw-r--   1 monty    my          53248 Apr 17 19:00 station.MYI
     -rw-rw-r--   1 monty    my           5767 Apr 17 19:00 station.frm

     shell> myisamchk -dvv station

     MyISAM file:     station
     Isam-version:  2
     Creation time: 1996-03-13 10:08:58
     Recover time:  1997-02-02  3:06:43
     Data records:              1192  Deleted blocks:              0
     Datafile parts:            1192  Deleted data:                0
     Datafile pointer (bytes):     2  Keyfile pointer (bytes):     2
     Max datafile length:   54657023  Max keyfile length:   33554431
     Recordlength:               834
     Record format: Fixed length

     table description:
     Key Start Len Index   Type                 Root  Blocksize    Rec/key
     1   2     4   unique  unsigned long        1024       1024          1
     2   32    30  multip. text                10240       1024          1

     Field Start Length Type
     1     1     1
     2     2     4
     3     6     4
     4     10    1
     5     11    20
     6     31    1
     7     32    30
     8     62    35
     9     97    35
     10    132   35
     11    167   4
     12    171   16
     13    187   35
     14    222   4
     15    226   16
     16    242   20
     17    262   20
     18    282   20
     19    302   30
     20    332   4
     21    336   4
     22    340   1
     23    341   8
     24    349   8
     25    357   8
     26    365   2
     27    367   2
     28    369   4
     29    373   4
     30    377   1
     31    378   2
     32    380   8
     33    388   4
     34    392   4
     35    396   4
     36    400   4
     37    404   1
     38    405   4
     39    409   4
     40    413   4
     41    417   4
     42    421   4
     43    425   4
     44    429   20
     45    449   30
     46    479   1
     47    480   1
     48    481   79
     49    560   79
     50    639   79
     51    718   79
     52    797   8
     53    805   1
     54    806   1
     55    807   20
     56    827   4
     57    831   4

     shell> myisampack station.MYI
     Compressing station.MYI: (1192 records)
     - Calculating statistics

     normal:     20  empty-space:   16  empty-zero:     12  empty-fill:  11
     pre-space:   0  end-space:     12  table-lookups:   5  zero:         7
     Original trees:  57  After join: 17
     - Compressing file
     87.14%
     Remember to run myisamchk -rq on compressed tables

     shell> ls -l station.*
     -rw-rw-r--   1 monty    my         127874 Apr 17 19:00 station.MYD
     -rw-rw-r--   1 monty    my          55296 Apr 17 19:04 station.MYI
     -rw-rw-r--   1 monty    my           5767 Apr 17 19:00 station.frm

     shell> myisamchk -dvv station

     MyISAM file:     station
     Isam-version:  2
     Creation time: 1996-03-13 10:08:58
     Recover time:  1997-04-17 19:04:26
     Data records:               1192  Deleted blocks:              0
     Datafile parts:             1192  Deleted data:                0
     Datafile pointer (bytes):      3  Keyfile pointer (bytes):     1
     Max datafile length:    16777215  Max keyfile length:     131071
     Recordlength:                834
     Record format: Compressed

     table description:
     Key Start Len Index   Type                 Root  Blocksize    Rec/key
     1   2     4   unique  unsigned long       10240       1024          1
     2   32    30  multip. text                54272       1024          1

     Field Start Length Type                         Huff tree  Bits
     1     1     1      constant                             1     0
     2     2     4      zerofill(1)                          2     9
     3     6     4      no zeros, zerofill(1)                2     9
     4     10    1                                           3     9
     5     11    20     table-lookup                         4     0
     6     31    1                                           3     9
     7     32    30     no endspace, not_always              5     9
     8     62    35     no endspace, not_always, no empty    6     9
     9     97    35     no empty                             7     9
     10    132   35     no endspace, not_always, no empty    6     9
     11    167   4      zerofill(1)                          2     9
     12    171   16     no endspace, not_always, no empty    5     9
     13    187   35     no endspace, not_always, no empty    6     9
     14    222   4      zerofill(1)                          2     9
     15    226   16     no endspace, not_always, no empty    5     9
     16    242   20     no endspace, not_always              8     9
     17    262   20     no endspace, no empty                8     9
     18    282   20     no endspace, no empty                5     9
     19    302   30     no endspace, no empty                6     9
     20    332   4      always zero                          2     9
     21    336   4      always zero                          2     9
     22    340   1                                           3     9
     23    341   8      table-lookup                         9     0
     24    349   8      table-lookup                        10     0
     25    357   8      always zero                          2     9
     26    365   2                                           2     9
     27    367   2      no zeros, zerofill(1)                2     9
     28    369   4      no zeros, zerofill(1)                2     9
     29    373   4      table-lookup                        11     0
     30    377   1                                           3     9
     31    378   2      no zeros, zerofill(1)                2     9
     32    380   8      no zeros                             2     9
     33    388   4      always zero                          2     9
     34    392   4      table-lookup                        12     0
     35    396   4      no zeros, zerofill(1)               13     9
     36    400   4      no zeros, zerofill(1)                2     9
     37    404   1                                           2     9
     38    405   4      no zeros                             2     9
     39    409   4      always zero                          2     9
     40    413   4      no zeros                             2     9
     41    417   4      always zero                          2     9
     42    421   4      no zeros                             2     9
     43    425   4      always zero                          2     9
     44    429   20     no empty                             3     9
     45    449   30     no empty                             3     9
     46    479   1                                          14     4
     47    480   1                                          14     4
     48    481   79     no endspace, no empty               15     9
     49    560   79     no empty                             2     9
     50    639   79     no empty                             2     9
     51    718   79     no endspace                         16     9
     52    797   8      no empty                             2     9
     53    805   1                                          17     1
     54    806   1                                           3     9
     55    807   20     no empty                             3     9
     56    827   4      no zeros, zerofill(2)                2     9
     57    831   4      no zeros, zerofill(1)                2     9

`myisampack' displays the following kinds of information:

   * `normal'

     The number of columns for which no extra packing is used.

   * `empty-space'

     The number of columns containing values that are only spaces.
     These occupy one bit.

   * `empty-zero'

     The number of columns containing values that are only binary
     zeros. These occupy one bit.

   * `empty-fill'

     The number of integer columns that do not occupy the full byte
     range of their type. These are changed to a smaller type. For
     example, a `BIGINT' column (eight bytes) can be stored as a
     `TINYINT' column (one byte) if all its values are in the range from
     `-128' to `127'.

   * `pre-space'

     The number of decimal columns that are stored with leading spaces.
     In this case, each value contains a count for the number of
     leading spaces.

   * `end-space'

     The number of columns that have a lot of trailing spaces. In this
     case, each value contains a count for the number of trailing
     spaces.

   * `table-lookup'

     The column had only a small number of different values, which were
     converted to an `ENUM' before Huffman compression.

   * `zero'

     The number of columns for which all values are zero.

   * `Original trees'

     The initial number of Huffman trees.

   * `After join'

     The number of distinct Huffman trees left after joining trees to
     save some header space.

After a table has been compressed, `myisamchk -dvv' prints additional
information about each column:

   * `Type'

     The data type. The value may contain any of the following
     descriptors:

        * `constant'

          All rows have the same value.

        * `no endspace'

          Do not store endspace.

        * `no endspace, not_always'

          Do not store endspace and do not do endspace compression for
          all values.

        * `no endspace, no empty'

          Do not store endspace. Do not store empty values.

        * `table-lookup'

          The column was converted to an `ENUM'.

        * `zerofill(N)'

          The most significant N bytes in the value are always 0 and
          are not stored.

        * `no zeros'

          Do not store zeros.

        * `always zero'

          Zero values are stored using one bit.

   * `Huff tree'

     The number of the Huffman tree associated with the column.

   * `Bits'

     The number of bits used in the Huffman tree.

After you run `myisampack', you must run `myisamchk' to re-create any
indexes. At this time, you can also sort the index blocks and create
statistics needed for the MySQL optimizer to work more efficiently:

     shell> myisamchk -rq --sort-index --analyze TBL_NAME.MYI

After you have installed the packed table into the MySQL database
directory, you should execute `mysqladmin flush-tables' to force
`mysqld' to start using the new table.

To unpack a packed table, use the `--unpack' option to `myisamchk'.


File: manual.info,  Node: mysqlaccess,  Next: mysqlbinlog,  Prev: myisampack,  Up: programs-admin-utils

4.6.6 `mysqlaccess' -- Client for Checking Access Privileges
------------------------------------------------------------

`mysqlaccess' is a diagnostic tool that Yves Carlier has provided for
the MySQL distribution. It checks the access privileges for a hostname,
username, and database combination. Note that `mysqlaccess' checks
access using only the `user', `db', and `host' tables. It does not
check table, column, or routine privileges specified in the
`tables_priv', `columns_priv', or `procs_priv' tables.

Invoke `mysqlaccess' like this:

     shell> mysqlaccess [HOST_NAME [USER_NAME [DB_NAME]]] [OPTIONS]

`mysqlaccess' understands the following options:

*`mysqlaccess' Option Reference*

*Format*       *Config File*  *Description*                        *Introduction*
-brief         brief          Generate reports in single-line      
                              tabular format                       
-commit        commit         Copy the new access privileges from  
                              the temporary tables to the          
                              original grant tables                
-copy          copy           Reload the temporary grant tables    
                              from original ones                   
-db=db_name    db             Specify the database name            
-debug=#       debug          Specify the debug level              
-help                         Display help message and exit        
-host=host_namehost           Connect to the MySQL server on the   
                              given host                           
-howto         howto          Display some examples that show how  
                              to use mysqlaccess                   
-old_server    old_server     Assume that the server is an old     
                              MySQL server (prior to MySQL  3.21)  
-password[=password]password       The password to use when connecting  
                              to the server                        
-plan          plan           Display suggestions and ideas for    
                              future releases                      
-preview       preview        Show the privilege differences       
                              after making changes to the          
                              temporary grant tables               
-relnotes      relnotes       Display the release notes            
-rhost=host_namerhost          Connect to the MySQL server on the   
                              given host                           
-rollback      rollback       Undo the most recent changes to the  
                              temporary grant tables.              
-spassword[=password]spassword      The password to use when connecting  
                              to the server as the superuser       
-superuser=user_namesuperuser      Specify the username for connecting  
                              as the superuser                     
-table         table          Generate reports in table format     
-user=user_name,user           The MySQL username to use when       
                              connecting                           
-version                      Display version information and exit 

   *  `--help', `-?'

     Display a help message and exit.

   *  `--brief', `-b'

     Generate reports in single-line tabular format.

   *  `--commit'

     Copy the new access privileges from the temporary tables to the
     original grant tables. The grant tables must be flushed for the
     new privileges to take effect. (For example, execute a `mysqladmin
     reload' command.)

   *  `--copy'

     Reload the temporary grant tables from original ones.

   *  `--db=DB_NAME', `-d DB_NAME'

     Specify the database name.

   *  `--debug=N'

     Specify the debug level. N can be an integer from 0 to 3.

   *  `--host=HOST_NAME', `-h HOST_NAME'

     The hostname to use in the access privileges.

   *  `--howto'

     Display some examples that show how to use `mysqlaccess'.

   *  `--old_server'

     Assume that the server is an old MySQL server (before MySQL 3.21)
     that does not yet know how to handle full `WHERE' clauses.

   *  `--password[=PASSWORD]', `-p[PASSWORD]'

     The password to use when connecting to the server. If you omit the
     PASSWORD value following the `--password' or `-p' option on the
     command line, you are prompted for one.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security::.

   *  `--plan'

     Display suggestions and ideas for future releases.

   *  `--preview'

     Show the privilege differences after making changes to the
     temporary grant tables.

   *  `--relnotes'

     Display the release notes.

   *  `--rhost=HOST_NAME', `-H HOST_NAME'

     Connect to the MySQL server on the given host.

   *  `--rollback'

     Undo the most recent changes to the temporary grant tables.

   *  `--spassword[=PASSWORD]', `-P[PASSWORD]'

     The password to use when connecting to the server as the
     superuser. If you omit the PASSWORD value following the
     `--password' or `-p' option on the command line, you are prompted
     for one.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security::.

   *  `--superuser=USER_NAME', `-U USER_NAME'

     Specify the username for connecting as the superuser.

   *  `--table', `-t'

     Generate reports in table format.

   *  `--user=USER_NAME', `-u USER_NAME'

     The username to use in the access privileges.

   *  `--version', `-v'

     Display version information and exit.

If your MySQL distribution is installed in some non-standard location,
you must change the location where `mysqlaccess' expects to find the
`mysql' client. Edit the `mysqlaccess' script at approximately line 18.
Search for a line that looks like this:

     $MYSQL     = '/usr/local/bin/mysql';    # path to mysql executable

Change the path to reflect the location where `mysql' actually is
stored on your system. If you do not do this, a `Broken pipe' error will
occur when you run `mysqlaccess'.


File: manual.info,  Node: mysqlbinlog,  Next: mysqlhotcopy,  Prev: mysqlaccess,  Up: programs-admin-utils

4.6.7 `mysqlbinlog' -- Utility for Processing Binary Log Files
--------------------------------------------------------------

The server's binary log consists of files that contain `events' that
describe modifications to database contents. The server writes binary
log files in binary format.  To display these files in text format, use
the `mysqlbinlog' utility. You can also use `mysqlbinlog' to display
relay log files written by a slave server in a replication setup. Relay
logs have the same format as binary log files. The binary log and relay
log are discussed further in *Note binary-log::, and *Note slave-logs::.

Invoke `mysqlbinlog' like this:

     shell> mysqlbinlog [OPTIONS] LOG_FILE ...

For example, to display the contents of the binary log file named
`binlog.000003', use this command:

     shell> mysqlbinlog binlog.0000003

The output includes all events contained in `binlog.000003'. Event
information includes the statement executed, the time the statement
took, the thread ID of the client that issued it, the timestamp when it
was executed, and so forth.

The output from `mysqlbinlog' can be re-executed (for example, by using
it as input to `mysql') to reapply the statements in the log.  This is
useful for recovery operations after a server crash. For other usage
examples, see the discussion later in this section.

Normally, you use `mysqlbinlog' to read binary log files directly and
apply them to the local MySQL server. It is also possible to read
binary logs from a remote server by using the
`--read-from-remote-server' option.  When you read remote binary logs,
the connection parameter options can be given to indicate how to
connect to the server.  These options are `--host', `--password',
`--port', `--protocol', `--socket', and `--user'; they are ignored
except when you also use the `--read-from-remote-server' option.

*`mysqlbinlog' Option Reference*

*Format*       *Config File*  *Description*                        *Introduction*
-base64-output base64-output  Print all binary log entries using   5.1.5
                              base64 encoding                      
-character-sets-dir=pathcharacter-sets-dirThe directory where character sets   
                              are installed                        
-database=db_namedatabase       List entries for just this database  
-debug[=debug_options]debug          Write a debugging log                
-debug-check   debug-check    Print debugging information when     5.1.21
                              the program exits                    
-debug-info    debug-info     Print debugging information, memory  5.1.21
                              and CPU statistics when the          
                              program exits                        
-disable-log-bindisable-log-binDisable binary logging               
-force-read    force-read     If mysqlbinlog reads a binary log    
                              event that it does not  recognize,   
                              it prints a warning                  
-help                         Display help message and exit        
-H             hexdump        Display a hex dump of the log in     5.1.2
                              comments                             
-host=host_namehost           Connect to the MySQL server on the   
                              given host                           
-local-load=pathlocal-load     Prepare local temporary files for    
                              LOAD DATA INFILE in the  specified   
                              directory                            
-offset=#      offset         Skip the first N entries in the log  
-password[=password]password       The password to use when connecting  
                              to the server                        
-port=port_num port           The TCP/IP port number to use for    
                              the connection                       
-protocol=type protocol       The connection protocol to use       
-read-from-remote-serverread-from-remote-serverRead the binary log from a MySQL     
                              server rather than reading a  local  
                              log file                             
-result-file=nameresult-file    Direct output to the given file      
-server-id=id  server-id      Extract only those events created    5.1.4
                              by the server having the given       
                              server ID                            
-set-charset=charset_nameset-charset    Add a SET NAMES charset_name         5.1.12
                              statement to the output              
-short-form    short-form     Display only the statements          
                              contained in the log                 
-socket=path   socket         For connections to localhost         
-start-datetime=datetimestart-datetime Start reading the binary log at the  
                              first event having a timestamp       
                              equal to or later than the datetime  
                              argument                             
-start-position=#start-position Start reading the binary log at the  
                              first event having a position        
                              equal to the N argument              
-stop-datetime=datetimestop-datetime  Stop reading the binary log at the   
                              first event having a timestamp       
                              equal or posterior to the datetime   
                              argument                             
-stop-position=#stop-position  Stop reading the binary log at the   
                              first event having a position        
                              equal or greater than the N argument 
-to-last-log   to-last-log    Do not stop at the end of the        
                              requested binary log from a MySQL    
                              server, but rather continue          
                              printing until the end of the last   
                              binary log                           
-user=user_name,user           The MySQL username to use when       
                              connecting to the server             
-version                      Display version information and exit 

`mysqlbinlog' supports the following options:

   *  `--help', `-?'

     Display a help message and exit.

   *  `--base64-output'

     Print all binary log entries using base64 encoding. This is for
     debugging only. Logs produced using this option should not be
     applied on production systems. This option was added in MySQL
     5.1.5.

   *  `--character-sets-dir=PATH'

     The directory where character sets are installed. See *Note
     charset-configuration::.

   *  `--database=DB_NAME', `-d DB_NAME'

     List entries for just this database (local log only). You can only
     specify one database with this option - if you specify multiple
     `--database' options, only the last one is used. This option forces
     `mysqlbinlog' to output entries from the binary log where the
     default database (that is, the one selected by `USE') is DB_NAME.
     Note that this does not replicate cross-database statements such
     as `UPDATE SOME_DB.SOME_TABLE SET foo='bar'' while having selected
     a different database or no database.

   *  `--debug[=DEBUG_OPTIONS]', `-# [DEBUG_OPTIONS]'

     Write a debugging log. A typical DEBUG_OPTIONS string is often
     `'d:t:o,FILE_NAME''.

   *  `--debug-check'

     Print some debugging information when the program exits.  This
     option was added in MySQL 5.1.21.

   *  `--debug-info'

     Print debugging information and memory and CPU usage statistics
     when the program exits. This option was added in MySQL 5.1.21.

   *  `--disable-log-bin', `-D'

     Disable binary logging. This is useful for avoiding an endless
     loop if you use the `--to-last-log' option and are sending the
     output to the same MySQL server.  This option also is useful when
     restoring after a crash to avoid duplication of the statements you
     have logged.

     This option requires that you have the `SUPER' privilege. It causes
     `mysqlbinlog' to include a `SET SQL_LOG_BIN=0' statement in its
     output to disable binary logging of the remaining output. The
     `SET' statement is ineffective unless you have the `SUPER'
     privilege.

   *  `--force-read', `-f'

     With this option, if `mysqlbinlog' reads a binary log event that
     it does not recognize, it prints a warning, ignores the event, and
     continues. Without this option, `mysqlbinlog' stops if it reads
     such an event.

   *  `--hexdump', `-H'

     Display a hex dump of the log in comments. This output can be
     helpful for replication debugging. Hex dump format is discussed
     later in this section. This option was added in MySQL 5.1.2.

   *  `--host=HOST_NAME', `-h HOST_NAME'

     Get the binary log from the MySQL server on the given host.

   *  `--local-load=PATH', `-l PATH'

     Prepare local temporary files for `LOAD DATA INFILE' in the
     specified directory.

   *  `--offset=N', `-o N'

     Skip the first N entries in the log.

   *  `--password[=PASSWORD]', `-p[PASSWORD]'

     The password to use when connecting to the server. If you use the
     short option form (`-p'), you _cannot_ have a space between the
     option and the password. If you omit the PASSWORD value following
     the `--password' or `-p' option on the command line, you are
     prompted for one.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security::.

   *  `--port=PORT_NUM', `-P PORT_NUM'

     The TCP/IP port number to use for connecting to a remote server.

   *  `--position=N', `-j N'

     Deprecated. Use `--start-position' instead.

   *  `--protocol={TCP|SOCKET|PIPE|MEMORY}'

     The connection protocol to use for connecting to the server.  It
     is useful when the other connection parameters normally would
     cause a protocol to be used other than the one you want. For
     details on the allowable values, see *Note connecting::.

   *  `--read-from-remote-server', `-R'

     Read the binary log from a MySQL server rather than reading a
     local log file. Any connection parameter options are ignored
     unless this option is given as well. These options are `--host',
     `--password', `--port', `--protocol', `--socket', and `--user'.

     This option requires that the remote server be running. It works
     only for binary log files on the remote server, not relay log
     files.

   *  `--result-file=NAME', `-r NAME'

     Direct output to the given file.

   *  `--server-id=ID'

     Extract only those events created by the server having the given
     server ID. This option is available as of MySQL 5.1.4.

   *  `--set-charset=CHARSET_NAME'

     Add a `SET NAMES CHARSET_NAME' statement to the output to specify
     the character set to be used for processing log files. This option
     was added in MySQL 5.1.12.

   *  `--short-form', `-s'

     Display only the statements contained in the log, without any
     extra information.

   *  `--socket=PATH', `-S PATH'

     For connections to `localhost', the Unix socket file to use, or,
     on Windows, the name of the named pipe to use.

   *  `--start-datetime=DATETIME'

     Start reading the binary log at the first event having a timestamp
     equal to or later than the DATETIME argument. The DATETIME value
     is relative to the local time zone on the machine where you run
     `mysqlbinlog'. The value should be in a format accepted for the
     `DATETIME' or `TIMESTAMP' data types. For example:

          shell> mysqlbinlog --start-datetime="2005-12-25 11:25:56" binlog.000003

     This option is useful for point-in-time recovery. See *Note
     backup-strategy-example::.

   *  `--stop-datetime=DATETIME'

     Stop reading the binary log at the first event having a timestamp
     equal or posterior to the DATETIME argument. This option is useful
     for point-in-time recovery. See the description of the
     `--start-datetime' option for information about the DATETIME value.

   *  `--start-position=N'

     Start reading the binary log at the first event having a position
     equal to the N argument.  This option applies to the first log
     file named on the command line.

   *  `--stop-position=N'

     Stop reading the binary log at the first event having a position
     equal or greater than the N argument. This option applies to the
     last log file named on the command line.

   *  `--to-last-log', `-t'

     Do not stop at the end of the requested binary log from a MySQL
     server, but rather continue printing until the end of the last
     binary log. If you send the output to the same MySQL server, this
     may lead to an endless loop. This option requires
     `--read-from-remote-server'.

   *  `--user=USER_NAME', `-u USER_NAME'

     The MySQL username to use when connecting to a remote server.

   *  `--version', `-V'

     Display version information and exit.

   *  `--write-binlog'

     This option is enabled by default, so that `ANALYZE TABLE',
     `OPTIMIZE TABLE', and `REPAIR TABLE' statements generated by
     `mysqlcheck' are written to the binary log.  Use
     `--skip-write-binlog' to cause `NO_WRITE_TO_BINLOG' to be added to
     the statements so that they are not logged. Use the
     `--skip-write-binlog' when these statements should not be sent to
     replication slaves or run when using the binary logs for recovery
     from backup. This option was added in MySQL 5.1.18.

You can also set the following variable by using `--VAR_NAME=VALUE'
syntax:

   *  `open_files_limit'

     Specify the number of open file descriptors to reserve.

You can pipe the output of `mysqlbinlog' into the `mysql' client to
execute the statements contained in the binary log. This is used to
recover from a crash when you have an old backup (see *Note backup::).
For example:

     shell> mysqlbinlog binlog.000001 | mysql

Or:

     shell> mysqlbinlog binlog.[0-9]* | mysql

You can also redirect the output of `mysqlbinlog' to a text file
instead, if you need to modify the statement log first (for example, to
remove statements that you do not want to execute for some reason).
After editing the file, execute the statements that it contains by
using it as input to the `mysql' program.

`mysqlbinlog' has the `--start-position' option, which prints only
those statements with an offset in the binary log greater than or equal
to a given position (the given position must match the start of one
event). It also has options to stop and start when it sees an event
with a given date and time. This enables you to perform point-in-time
recovery using the `--stop-datetime' option (to be able to say, for
example, `roll forward my databases to how they were today at 10:30
a.m.').

If you have more than one binary log to execute on the MySQL server,
the safe method is to process them all using a single connection to the
server. Here is an example that demonstrates what may be _unsafe_:

     shell> mysqlbinlog binlog.000001 | mysql # DANGER!!
     shell> mysqlbinlog binlog.000002 | mysql # DANGER!!

Processing binary logs this way using different connections to the
server causes problems if the first log file contains a `CREATE
TEMPORARY TABLE' statement and the second log contains a statement that
uses the temporary table.  When the first `mysql' process terminates,
the server drops the temporary table. When the second `mysql' process
attempts to use the table, the server reports `unknown table.'

To avoid problems like this, use a _single_ connection to execute the
contents of all binary logs that you want to process. Here is one way
to do so:

     shell> mysqlbinlog binlog.000001 binlog.000002 | mysql

Another approach is to write all the logs to a single file and then
process the file:

     shell> mysqlbinlog binlog.000001 >  /tmp/statements.sql
     shell> mysqlbinlog binlog.000002 >> /tmp/statements.sql
     shell> mysql -e "source /tmp/statements.sql"

`mysqlbinlog' can produce output that reproduces a `LOAD DATA INFILE'
operation without the original data file. `mysqlbinlog' copies the data
to a temporary file and writes a `LOAD DATA LOCAL INFILE' statement
that refers to the file.  The default location of the directory where
these files are written is system-specific. To specify a directory
explicitly, use the `--local-load' option.

Because `mysqlbinlog' converts `LOAD DATA INFILE' statements to `LOAD
DATA LOCAL INFILE' statements (that is, it adds `LOCAL'), both the
client and the server that you use to process the statements must be
configured to allow `LOCAL' capability. See *Note load-data-local::.

MySQL Enterprise

For expert advice on the security implications of enabling `LOCAL',
subscribe to the MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

*Warning*:

The temporary files created for `LOAD DATA LOCAL' statements are _not_
automatically deleted because they are needed until you actually
execute those statements. You should delete the temporary files
yourself after you no longer need the statement log. The files can be
found in the temporary file directory and have names like
ORIGINAL_FILE_NAME-#-#.

The `--hexdump' option produces a hex dump of the log contents in
`#'-format comments:

     shell> mysqlbinlog --hexdump master-bin.000001

With the preceding command, the output might look like this:

     /*!40019 SET @@session.max_insert_delayed_threads=0*/;
     /*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/;
     # at 4
     #051024 17:24:13 server id 1  end_log_pos 98
     # Position  Timestamp   Type   Master ID        Size      Master Pos    Flags
     # 00000004 9d fc 5c 43   0f   01 00 00 00   5e 00 00 00   62 00 00 00   00 00
     # 00000017 04 00 35 2e 30 2e 31 35  2d 64 65 62 75 67 2d 6c |..5.0.15.debug.l|
     # 00000027 6f 67 00 00 00 00 00 00  00 00 00 00 00 00 00 00 |og..............|
     # 00000037 00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00 |................|
     # 00000047 00 00 00 00 9d fc 5c 43  13 38 0d 00 08 00 12 00 |.......C.8......|
     # 00000057 04 04 04 04 12 00 00 4b  00 04 1a                |.......K...|
     #       Start: binlog v 4, server v 5.0.15-debug-log created 051024 17:24:13
     #       at startup
     ROLLBACK;

Hex dump output currently contains the following elements. This format
might change in the future.

   * `Position': The byte position within the log file.

   * `Timestamp': The event timestamp. In the example shown, `'9d fc 5c
     43'' is the representation of `'051024 17:24:13'' in hexadecimal.

   * `Type': The type of the log event. In the example shown, `'0f''
     means that the example event is a `FORMAT_DESCRIPTION_EVENT'. The
     following table lists the possible types.

     Type                               Name          Meaning
     `00'                               `UNKNOWN_EVENT'This event should never be present in the log.
     `01'                               `START_EVENT_V3'This indicates the start of a log file written by
                                                      MySQL 4 or earlier.
     `02'                               `QUERY_EVENT' The most common type of events. These contain
                                                      statements executed on the master.
     `03'                               `STOP_EVENT'  Indicates that master has stopped.
     `04'                               `ROTATE_EVENT'Written when the master switches to a new log
                                                      file.
     `05'                               `INTVAR_EVENT'Used mainly for `AUTO_INCREMENT' values and when
                                                      the `LAST_INSERT_ID()' function is used in the
                                                      statement.
     `06'                               `LOAD_EVENT'  Used for `LOAD DATA INFILE' in MySQL 3.23.
     `07'                               `SLAVE_EVENT' Reserved for future use.
     `08'                               `CREATE_FILE_EVENT'Used for `LOAD DATA INFILE' statements. This
                                                      indicates the start of execution of such a
                                                      statement. A temporary file is created on the
                                                      slave. Used in MySQL 4 only.
     `09'                               `APPEND_BLOCK_EVENT'Contains data for use in a `LOAD DATA INFILE'
                                                      statement. The data is stored in the temporary
                                                      file on the slave.
     `0a'                               `EXEC_LOAD_EVENT'Used for `LOAD DATA INFILE' statements. The
                                                      contents of the temporary file is stored in the
                                                      table on the slave. Used in MySQL 4 only.
     `0b'                               `DELETE_FILE_EVENT'Rollback of a `LOAD DATA INFILE' statement. The
                                                      temporary file should be deleted on slave.
     `0c'                               `NEW_LOAD_EVENT'Used for `LOAD DATA INFILE' in MySQL 4 and
                                                      earlier.
     `0d'                               `RAND_EVENT'  Used to send information about random values if
                                                      the `RAND()' function is used in the statement.
     `0e'                               `USER_VAR_EVENT'Used to replicate user variables.
     `0f'                               `FORMAT_DESCRIPTION_EVENT'This indicates the start of a log file written by
                                                      MySQL 5 or later.
     `10'                               `XID_EVENT'   Event indicating commit of an XA transaction.
     `11'                               `BEGIN_LOAD_QUERY_EVENT'Used for `LOAD DATA INFILE' statements in MySQL 5
                                                      and later.
     `12'                               `EXECUTE_LOAD_QUERY_EVENT'Used for `LOAD DATA INFILE' statements in MySQL 5
                                                      and later.
     `13'                               `TABLE_MAP_EVENT'Information about a table definition. Used in
                                                      MySQL 5.1 and later.
     `14'                               `PRE_GA_WRITE_ROWS_EVENT'Row data for a single table that should be
                                                      created. Used in MySQL 5.1.0 to 5.1.15.
     `15'                               `PRE_GA_UPDATE_ROWS_EVENT'Row data for a single table that needs to be
                                                      updated. Used in MySQL 5.1 to 5.1.15.
     `16'                               `PRE_GA_DELETE_ROWS_EVENT'Row data for a single table that should be
                                                      deleted. Used in MySQL 5.1 to 5.1.15.
     `17'                               `WRITE_ROWS_EVENT'Row data for a single table that should be
                                                      created. Used in MySQL 5.1.16 and later.
     `18'                               `UPDATE_ROWS_EVENT'Row data for a single table that needs to be
                                                      updated. Used in MySQL 5.1.16 and later.
     `19'                               `DELETE_ROWS_EVENT'Row data for a single table that should be
                                                      deleted. Used in MySQL 5.1.16 and later.
     `1a'                               `INCIDENT_EVENT'Something out of the ordinary happened. Added in
                                                      MySQL 5.1.18.

   * `Master ID': The server id of the master that created the event.

   * `Size': The size in bytes of the event.

   * `Master Pos': The position of the event in the original master log
     file.

   * `Flags': 16 flags. Currently, the following flags are used. The
     others are reserved for future use.

     Flag                               Name          Meaning
     `01'                               `LOG_EVENT_BINLOG_IN_USE_F'Log file correctly closed. (Used only in
                                                      `FORMAT_DESCRIPTION_EVENT'.) If this flag is set
                                                      (if the flags are, for example, `'01 00'') in a
                                                      `FORMAT_DESCRIPTION_EVENT', the log file has not
                                                      been properly closed. Most probably this is
                                                      because of a master crash (for example, due to
                                                      power failure).
     `02'                                             Reserved for future use.
     `04'                               `LOG_EVENT_THREAD_SPECIFIC_F'Set if the event is dependent on the connection
                                                      it was executed in (for example, `'04 00''), for
                                                      example, if the event uses temporary tables.
     `08'                               `LOG_EVENT_SUPPRESS_USE_F'Set in some circumstances when the event is not
                                                      dependent on the default database.


File: manual.info,  Node: mysqlhotcopy,  Next: instance-manager,  Prev: mysqlbinlog,  Up: programs-admin-utils

4.6.8 `mysqlhotcopy' -- A Database Backup Program
-------------------------------------------------

`mysqlhotcopy' is a Perl script that was originally written and
contributed by Tim Bunce. It uses `LOCK TABLES', `FLUSH TABLES', and
`cp' or `scp' to make a database backup quickly. It is the fastest way
to make a backup of the database or single tables, but it can be run
only on the same machine where the database directories are located.
`mysqlhotcopy' works only for backing up `MyISAM' and `ARCHIVE' tables.
It runs on Unix and NetWare.

     shell> mysqlhotcopy DB_NAME [/PATH/TO/NEW_DIRECTORY]

     shell> mysqlhotcopy DB_NAME_1 ... DB_NAME_N /PATH/TO/NEW_DIRECTORY

Back up tables in the given database that match a regular expression:

     shell> mysqlhotcopy DB_NAME./REGEX/

The regular expression for the table name can be negated by prefixing
it with a tilde (``~''):

     shell> mysqlhotcopy DB_NAME./~REGEX/

*`mysqlhotcopy' Option Reference*

*Format*       *Config File*  *Description*                        *Introduction*
-addtodest     addtodest      Do not rename target directory (if   
                              it exists); merely add files to  it  
-allowold      allowold       Do not abort if a target exists;     
                              rename it by adding an _old  suffix  
-checkpoint=db_name.tbl_namecheckpoint     Insert checkpoint entries            
-chroot=path   chroot         Base directory of the chroot jail    
                              in which mysqld operates             
-debug         debug          Write a debugging log                
-dryrun        dryrun         Report actions without performing    
                              them                                 
-flushlogs     flushlogs      Flush logs after all tables are      
                              locked                               
-help                         Display help message and exit        
-host=host_namehost           Connect to the MySQL server on the   
                              given host                           
-keepold       keepold        Do not delete previous (renamed)     
                              target when done                     
-noindices     noindices      Do not include full index files in   
                              the backup                           
-password[=password]password       The password to use when connecting  
                              to the server                        
-port=port_num port           The TCP/IP port number to use for    
                              the connection                       
-quiet         quiet          Be silent except for errors          
-regexp        regexp         Copy all databases with names that   
                              match the given regular  expression  
-resetmaster   resetmaster    Reset the binary log after locking   
                              all the tables                       
-resetslave    resetslave     Reset the master.info file after     
                              locking all the tables               
-socket=path   socket         For connections to localhost         
-tmpdir=path   tmpdir         The temporary directory              
-user=user_name,user           The MySQL username to use when       
                              connecting to the server             
-version                      Display version information and exit 

`mysqlhotcopy' supports the following options:

   *  `--help', `-?'

     Display a help message and exit.

   *  `--addtodest'

     Do not rename target directory (if it exists); merely add files to
     it.

   *  `--allowold'

     Do not abort if a target exists; rename it by adding an `_old'
     suffix.

   *  `--checkpoint=DB_NAME.TBL_NAME'

     Insert checkpoint entries into the specified database DB_NAME and
     table TBL_NAME.

   *  `--chroot=PATH'

     Base directory of the `chroot' jail in which `mysqld' operates. The
     PATH value should match that of the `--chroot' option given to
     `mysqld'.

   *  `--debug'

     Enable debug output.

   *  `--dryrun', `-n'

     Report actions without performing them.

   *  `--flushlog'

     Flush logs after all tables are locked.

   *  `--host=HOST_NAME', `-h HOST_NAME'

     The hostname of the local host to use for making a TCP/IP
     connection to the local server. By default, the connection is made
     to `localhost' using a Unix socket file.

   *  `--keepold'

     Do not delete previous (renamed) target when done.

   *  `--method=COMMAND'

     The method for copying files (`cp' or `scp').

   *  `--noindices'

     Do not include full index files in the backup. This makes the
     backup smaller and faster. The indexes for reloaded tables can be
     reconstructed later with `myisamchk -rq'.

   *  `--password=PASSWORD', `-pPASSWORD'

     The password to use when connecting to the server. Note that the
     password value is not optional for this option, unlike for other
     MySQL programs. You can use an option file to avoid giving the
     password on the command line.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security::.

   *  `--port=PORT_NUM', `-P PORT_NUM'

     The TCP/IP port number to use when connecting to the local server.

   *  `--quiet', `-q'

     Be silent except for errors.

   *  `--record_log_pos=DB_NAME.TBL_NAME'

     Record master and slave status in the specified database DB_NAME
     and table TBL_NAME.

   *  `--regexp=EXPR'

     Copy all databases with names that match the given regular
     expression.

   *  `--resetmaster'

     Reset the binary log after locking all the tables.

   *  `--resetslave'

     Reset the `master.info' file after locking all the tables.

   *  `--socket=PATH', `-S PATH'

     The Unix socket file to use for the connection.

   *  `--suffix=STR'

     The suffix for names of copied databases.

   *  `--tmpdir=PATH'

     The temporary directory. The default is `/tmp'.

   *  `--user=USER_NAME', `-u USER_NAME'

     The MySQL username to use when connecting to the server.

`mysqlhotcopy' reads the `[client]' and `[mysqlhotcopy]' option groups
from option files.

To execute `mysqlhotcopy', you must have access to the files for the
tables that you are backing up, the `SELECT' privilege for those
tables, the `RELOAD' privilege (to be able to execute `FLUSH TABLES'),
and the `LOCK TABLES' privilege (to be able to lock the tables).

Use `perldoc' for additional `mysqlhotcopy' documentation, including
information about the structure of the tables needed for the
`--checkpoint' and `--record_log_pos' options:

     shell> perldoc mysqlhotcopy

MySQL Enterprise

MySQL Enterprise subscribers will find more information about
`mysqlhotcopy' in the Knowledge Base article, How Does mysqlhotcopy
Work? (https://kb.mysql.com/view.php?id=5919). Access to the MySQL
Knowledge Base collection of articles is one of the advantages of
subscribing to MySQL Enterprise. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: instance-manager,  Next: mysql-convert-table-format,  Prev: mysqlhotcopy,  Up: programs-admin-utils

4.6.9 `mysqlmanager' -- The MySQL Instance Manager
--------------------------------------------------

* Menu:

* instance-manager-command-options::  MySQL Instance Manager Command Options
* instance-manager-configuration-files::  MySQL Instance Manager Configuration Files
* instance-manager-startup-process::  Starting the MySQL Server with MySQL Instance Manager
* instance-manager-security-passwords::  Instance Manager User and Password Management
* instance-manager-security-monitoring::  MySQL Server Instance Status Monitoring
* instance-manager-security::    Connecting to MySQL Instance Manager
* instance-manager-commands::    MySQL Instance Manager Commands

*Important*:

MySQL Instance Manager has been deprecated and is removed in MySQL 6.0.

`mysqlmanager' is the MySQL Instance Manager (IM). This program
monitors and manages MySQL Database Server instances. MySQL Instance
Manager is available for Unix-like operating systems, as well as
Windows. It runs as a daemon that listens on a TCP/IP port. On Unix, it
also listens on a Unix socket file.

MySQL Instance Manager can be used in place of the `mysqld_safe' script
to start and stop one or more instances of MySQL Server. Because
Instance Manager can manage multiple server instances, it can also be
used in place of the `mysqld_multi' script. Instance Manager offers
these capabilities:

   * Instance Manager can start and stop instances, and report on the
     status of instances.

   * Server instances can be treated as guarded or unguarded:

        * When Instance Manager starts, it starts each guarded
          instance. If the instance crashes, Instance Manager detects
          this and restarts it. When Instance Manager stops, it stops
          the instance.

        * A nonguarded instance is not started when Instance Manager
          starts or monitored by it. If the instance crashes after
          being started, Instance Manager does not restart it. When
          Instance Manager exits, it does not stop the instance if it
          is running.

     Instances are guarded by default. An instance can be designated as
     nonguarded by including the `nonguarded' option in the
     configuration file.

   * Instance Manager provides an interactive interface for configuring
     instances, so that the need to edit the configuration file
     manually is reduced or eliminated.

   * Instance Manager provides remote instance management. That is, it
     runs on the host where you want to control MySQL Server instances,
     but you can connect to it from a remote host to perform
     instance-management operations.

The following sections describe MySQL Instance Manager operation in
more detail.


File: manual.info,  Node: instance-manager-command-options,  Next: instance-manager-configuration-files,  Prev: instance-manager,  Up: instance-manager

4.6.9.1 MySQL Instance Manager Command Options
..............................................

*Important*:

MySQL Instance Manager has been deprecated and is removed in MySQL 6.0.

The MySQL Instance Manager supports a number of command options.  For a
brief listing, invoke `mysqlmanager' with the `--help' option. Options
may be given on the command line or in the Instance Manager
configuration file. On Windows, the standard configuration file is
`my.ini' in the directory where Instance Manager is installed. On Unix,
the standard file is `/etc/my.cnf'. To specify a different
configuration file, start Instance Manager with the `--defaults-file'
option.

`mysqlmanager' supports the options described in the following list.
The options for managing entries in the password file are described
further in *Note instance-manager-security-passwords::.

   * `--help', `-?'

     Display a help message and exit.

   * `--add-user'

     Add a new user (specified with the `--username' option) to the
     password file.  This option was added in MySQL 5.1.12.

   * `--angel-pid-file=FILE_NAME'

     The file in which the angel process records its process ID when
     `mysqlmanager' runs in daemon mode (that is, when the
     `--run-as-service' option is given). The default filename is
     `mysqlmanager.angel.pid'.

     If the `--angel-pid-file' option is not given, the default angel
     PID file has the same name as the PID file except that any PID
     file extension is replaced with an extension of `.angel.pid'. (For
     example, `mysqlmanager.pid' becomes `mysqlmanager.angel.pid'.)

     This option was added in MySQL 5.1.11.

   * `--bind-address=IP'

     The IP address to bind to.

   * `--check-password-file'

     Check the validity and consistency of the password file.  This
     option was added in MySQL 5.1.12.

   * `--clean-password-file'

     Drop all users from the password file. This option was added in
     MySQL 5.1.12.

   * `--debug=DEBUG_OPTIONS, -# DEBUG_OPTIONS'

     Write a debugging log. The DEBUG_OPTIONS string often is
     `'d:t:o,FILE_NAME''.  This option was added in MySQL 5.1.10.

   * `--default-mysqld-path=PATH'

     The pathname of the MySQL Server binary. This pathname is used for
     all server instance sections in the configuration file for which
     no `mysqld-path' option is present. The default value of this
     option is the compiled-in pathname, which depends on how the MySQL
     distribution was configured. Example:
     `--default-mysqld-path=/usr/sbin/mysqld'

   * `--defaults-file=FILE_NAME'

     Read Instance Manager and MySQL Server settings from the given
     file. All configuration changes made by the Instance Manager will
     be written to this file. This must be the first option on the
     command line if it is used, and the file must exist.

     If this option is not given, Instance Manager uses its standard
     configuration file. On Windows, the standard file is `my.ini' in
     the directory where Instance Manager is installed. On Unix, the
     standard file is `/etc/my.cnf'.

   * `--drop-user'

     Drop a user (specified with the `--username' option) from the
     password file. This option was added in MySQL 5.1.12.

   * `--edit-user'

     Change an entry for an existing user (specified with the
     `--username' option) in the password file.  This option was added
     in MySQL 5.1.12.

   * `--install'

     On Windows, install Instance Manager as a Windows service.  The
     service name is `MySQL Manager'.

   * `--list-users'

     List the users in the password file. This option was added in
     MySQL 5.1.12.

   * `--log=FILE_NAME'

     The path to the Instance Manager log file. This option has no
     effect unless the `--run-as-service' option is also given. If the
     filename specified for the option is a relative name, the log file
     is created under the directory from which Instance Manager is
     started. To ensure that the file is created in a specific
     directory, specify it as a full pathname.

     If `--run-as-service' is given without `--log', the log file is
     `mysqlmanager.log' in the data directory.

     If `--run-as-service' is not given, log messages go to the
     standard output. To capture log output, you can redirect Instance
     Manager output to a file:

          mysqlmanager > im.log

   * `--monitoring-interval=SECONDS'

     The interval in seconds for monitoring server instances. The
     default value is 20 seconds. Instance Manager tries to connect to
     each monitored (guarded) instance using the non-existing
     `MySQL_Instance_Manager' user account to check whether it is
     alive/not hanging. If the result of the connection attempt
     indicates that the instance is unavailable, Instance Manager
     performs several attempts to restart the instance.

     Normally, the `MySQL_Instance_Manager' account does not exist, so
     the connection attempts by Instance Manager cause the monitored
     instance to produce messages in its general query log similar to
     the following:

          Access denied for user 'MySQL_Instance_M'@'localhost' »
              (using password: YES)

     The `nonguarded' option in the appropriate server instance section
     disables monitoring for a particular instance. If the instance
     dies after being started, Instance Manager will not restart it.
     Instance Manager tries to connect to a nonguarded instance only
     when you request the instance's status (for example, with the `SHOW
     INSTANCES' status.

     See *Note instance-manager-security-monitoring::, for more
     information.

   * `--mysqld-safe-compatible'

     Run in a `mysqld_safe'-compatible manner.  For details, see *Note
     instance-manager-startup-process::. This option was added in MySQL
     5.1.12.

   * `--password=PASSWORD', `-p PASSWORD'

     Specify the password for an entry to be added to or modified in
     the password file. Unlike the `--password'/`-P' option for most
     MySQL programs, the password value is required, not optional. This
     option was added in MySQL 5.1.12.

   * `--password-file=FILE_NAME'

     The name of the file where the Instance Manager looks for users
     and passwords. On Windows, the default is `mysqlmanager.passwd' in
     the directory where Instance Manager is installed. On Unix, the
     default file is `/etc/mysqlmanager.passwd'.

   * `--pid-file=FILE_NAME'

     The process ID file to use. On Windows, the default file is
     `mysqlmanager.pid' in the directory where Instance Manager is
     installed. On Unix, the default is `mysqlmanager.pid' in the data
     directory.

   * `--port=PORT_NUM'

     The port number to use when listening for TCP/IP connections from
     clients. The default port number (assigned by IANA) is 2273.

   * `--print-defaults'

     Print the current defaults and exit. This must be the first option
     on the command line if it is used.

   * `--print-password-line'

     Prepare an entry for the password file, print it to the standard
     output, and exit. You can redirect the output from Instance
     Manager to a file to save the entry in the file.

     Prior to MySQL 5.1.12, this option was named `--passwd'.

   * `--remove'

     On Windows, removes Instance Manager as a Windows service.  This
     assumes that Instance Manager has been run with `--install'
     previously.

   * `--run-as-service'

     On Unix, daemonize and start an angel process. The angel process
     monitors Instance Manager and restarts it if it crashes. (The
     angel process itself is simple and unlikely to crash.)

   * `--socket=PATH'

     On Unix, the socket file to use for incoming connections.  The
     default file is named `/tmp/mysqlmanager.sock'. This option has no
     meaning on Windows.

   * `--standalone'

     This option is used on Windows to run Instance Manager in
     standalone mode. You should specify it when you start Instance
     Manager from the command line.

   * `--user=USER_NAME'

     On Unix, the username of the system account to use for starting
     and running `mysqlmanager'. This option generates a warning and
     has no effect unless you start `mysqlmanager' as `root' (so that
     it can change its effective user ID), or as the named user. It is
     recommended that you configure `mysqlmanager' to run using the
     same account used to run the `mysqld' server. (`User' in this
     context refers to a system login account, not a MySQL user listed
     in the grant tables.)

   * `--username=USER_NAME', `-u USER_NAME'

     Specify the username for an entry to be added to or modified in
     the password file. This option was added in MySQL 5.1.12.

   * `--version', `-V'

     Display version information and exit.

   * `--wait-timeout=N'

     The number of seconds to wait for activity on an incoming
     connection before closing it. The default is 28800 seconds (8
     hours).

     This option was added in MySQL 5.1.7. Before that, the timeout is
     30 seconds and cannot be changed.


File: manual.info,  Node: instance-manager-configuration-files,  Next: instance-manager-startup-process,  Prev: instance-manager-command-options,  Up: instance-manager

4.6.9.2 MySQL Instance Manager Configuration Files
..................................................

*Important*:

MySQL Instance Manager has been deprecated and is removed in MySQL 6.0.

Instance Manager uses its standard configuration file unless it is
started with a `--defaults-file' option that specifies a different
file. On Windows, the standard file is `my.ini' in the directory where
Instance Manager is installed. On Unix, the standard file is
`/etc/my.cnf'.

Instance Manager reads options for itself from the `[manager]' section
of the configuration file, and options for server instances from
`[mysqld]' or `[mysqldN]' sections. The `[manager]' section contains any
of the options listed in *Note instance-manager-command-options::,
except for those specified as having to be given as the first option on
the command line. Here is a sample `[manager]' section:

     # MySQL Instance Manager options section
     [manager]
     default-mysqld-path = /usr/local/mysql/libexec/mysqld
     socket=/tmp/manager.sock
     pid-file=/tmp/manager.pid
     password-file = /home/cps/.mysqlmanager.passwd
     monitoring-interval = 2
     port = 1999
     bind-address = 192.168.1.5

Each `[mysqld]' or `[mysqldN]' instance section specifies options given
by Instance Manager to a server instance at startup. These are mainly
common MySQL Server options (see *Note server-options::). In addition, a
`[mysqldN]' section can contain the options in the following list,
which are specific to Instance Manager. These options are interpreted by
Instance Manager itself; it does not pass them to the server when it
attempts to start that server.

*Warning*:

The Instance Manager-specific options must not be used in a `[mysqld]'
section. If a server is started without using Instance Manager, it will
not recognize these options and will fail to start properly.

   * `mysqld-path = PATH'

     The pathname of the `mysqld' server binary to use for the server
     instance.

   * `nonguarded'

     This option disables Instance Manager monitoring functionality for
     the server instance. By default, an instance is guarded: At
     Instance Manager start time, it starts the instance. It also
     monitors the instance status and attempts to restart it if it
     fails. At Instance Manager exit time, it stops the instance. None
     of these things happen for nonguarded instances.

   * `shutdown-delay = SECONDS'

     The number of seconds Instance Manager should wait for the server
     instance to shut down. The default value is 35 seconds. After the
     delay expires, Instance Manager assumes that the instance is
     hanging and attempts to terminate it.  If you use `InnoDB' with
     large tables, you should increase this value.

Here are some sample instance sections:

     [mysqld1]
     mysqld-path=/usr/local/mysql/libexec/mysqld
     socket=/tmp/mysql.sock
     port=3307
     server_id=1
     skip-stack-trace
     core-file
     log-bin
     log-error
     log=mylog
     log-slow-queries

     [mysqld2]
     nonguarded
     port=3308
     server_id=2
     mysqld-path= /home/cps/mysql/trees/mysql-5.1/sql/mysqld
     socket     = /tmp/mysql.sock5
     pid-file   = /tmp/hostname.pid5
     datadir= /home/cps/mysql_data/data_dir1
     language=/home/cps/mysql/trees/mysql-5.1/sql/share/english
     log-bin
     log=/tmp/fordel.log


File: manual.info,  Node: instance-manager-startup-process,  Next: instance-manager-security-passwords,  Prev: instance-manager-configuration-files,  Up: instance-manager

4.6.9.3 Starting the MySQL Server with MySQL Instance Manager
.............................................................

*Important*:

MySQL Instance Manager has been deprecated and is removed in MySQL 6.0.

This section discusses how Instance Manager starts server instances
when it starts. However, before you start Instance Manager, you should
set up a password file for it. Otherwise, you will not be able to
connect to Instance Manager to control it after it starts. For details
about creating Instance Manager accounts, see *Note
instance-manager-security-passwords::.

On Unix, the `mysqld' MySQL database server normally is started with
the `mysql.server' script, which usually resides in the `/etc/init.d/'
folder. That script invokes the `mysqld_safe' script by default.
However, you can use Instance Manager instead if you modify the
`/etc/my.cnf' configuration file by adding `use-manager' to the
`[mysql.server]' section:

     [mysql.server]
     use-manager

Before MySQL 5.1.12, Instance Manager always tries to start at least
one server instance: When it starts, it reads its configuration file if
it exists to find server instance sections and prepare a list of
instances. Instance sections have names of the form `[mysqld]' or
`[mysqldN]', where N is an unsigned integer (for example, `[mysqld1]',
`[mysqld2]', and so forth).

After preparing the list of instances, Instance Manager starts the
guarded instances in the list. If there are no instances, Instance
Manager creates an instance named `mysqld' and attempts to start it
with default (compiled-in) configuration values. This means that the
Instance Manager cannot find the `mysqld' program if it is not
installed in the default location.  (*Note installation-layouts::,
describes default locations for components of MySQL distributions.) If
you have installed the MySQL server in a non-standard location, you
should create the Instance Manager configuration file.

The startup behavior just described is similar to that of
`mysqld_safe', which always attempts to start a server. However, it
lacks the flexibility required for some operations because it is not
possible to run Instance Manager in such a way that it refrains from
starting any server instances.  For example, you cannot invoke Instance
Manager for the purpose of configuring an instance without also
starting it (a task that a MySQL installer application might want to
perform).  Consequently, MySQL 5.1.12 introduces the following changes:

   * A new option, `--mysqld-safe-compatible', may be used to cause
     Instance Manager to run with startup behavior similar to that used
     before MySQL 5.1.12: If Instance Manager finds a `[mysqld]'
     instance section in the configuration file, it will start it. If
     Instance Manager finds no `[mysqld]' section, it creates one using
     default configuration values, writes a `[mysqld]' section to the
     configuration file if it is accessible, and starts the `mysqld'
     instance. Instance Manager also starts any other guarded instances
     listed in the configuration file.

   * Without `--mysqld-safe-compatible', Instance Manager reads its
     configuration file if it exists and starts instances for any
     guarded instance sections that it finds.  If there are none, it
     starts no instances.

Instance Manager also stops all guarded server instances when it shuts
down.

The allowable options for `[mysqldN]' server instance sections are
described in *Note instance-manager-configuration-files::. In these
sections, you can use a special `mysqld-path=PATH-TO-MYSQLD-BINARY'
option that is recognized only by Instance Manager. Use this option to
let Instance Manager know where the `mysqld' binary resides. If there
are multiple instances, it may also be necessary to set other options
such as `datadir' and `port', to ensure that each instance has a
different data directory and TCP/IP port number. *Note
multiple-servers::, discusses the configuration values that must differ
for each instance when you run multiple instance on the same machine.

*Warning*:

The `[mysqld]' instance section, if it exists, must not contain any
Instance Manager-specific options.

The typical Unix startup/shutdown cycle for a MySQL server with the
MySQL Instance Manager enabled is as follows:

  1. The `/etc/init.d/mysql' script starts MySQL Instance Manager.

  2. Instance Manager starts the guarded server instances and monitors
     them.

  3. If a server instance fails, Instance Manager restarts it.

  4. If Instance Manager is shut down (for example, with the
     `/etc/init.d/mysql stop' command), it shuts down all server
     instances.


File: manual.info,  Node: instance-manager-security-passwords,  Next: instance-manager-security-monitoring,  Prev: instance-manager-startup-process,  Up: instance-manager

4.6.9.4 Instance Manager User and Password Management
.....................................................

*Important*:

MySQL Instance Manager has been deprecated and is removed in MySQL 6.0.

The Instance Manager stores its user information in a password file. On
Windows, the default is `mysqlmanager.passwd' in the directory where
Instance Manager is installed. On Unix, the default file is
`/etc/mysqlmanager.passwd'. To specify a different location for the
password file, use the `--password-file' option.

If the password file does not exist or contains no password entries,
you cannot connect to the Instance Manager.

*Note*:

Any Instance Manager process that is running to monitor server
instances does not notice changes to the password file. You must stop
it and restart it after making password entry changes.

Entries in the password file have the following format, where the two
fields are the account username and encrypted password, separated by a
colon:

     petr:*35110DC9B4D8140F5DE667E28C72DD2597B5C848

Instance Manager password encryption is the same as that used by MySQL
Server. It is a one-way operation; no means are provided for decrypting
encrypted passwords.

Instance Manager accounts differ somewhat from MySQL Server accounts:

   * MySQL Server accounts are associated with a hostname, username,
     and password (see *Note user-names::).

   * Instance Manager accounts are associated with a username and
     password only.

This means that a client can connect to Instance Manager with a given
username from any host. To limit connections so that clients can
connect only from the local host, start Instance Manager with the
`--bind-address=127.0.0.1' option so that it listens only to the local
network interface.  Remote clients will not be able to connect. Local
clients can connect like this:

     shell> mysql -h 127.0.0.1 -P 2273

Before MySQL 5.1.12, the only option for creating password file entries
is `--passwd', which causes Instance Manager to prompt for username and
password values and display the resulting entry. You can save the
output in the `/etc/mysqlmanager.passwd' password file to store it.
Here is an example:

     shell> mysqlmanager --passwd >> /etc/mysqlmanager.passwd
     Creating record for new user.
     Enter user name: mike
     Enter password: mikepass
     Re-type password: mikepass

At the prompts, enter the username and password for the new Instance
Manager user. You must enter the password twice. It does not echo to
the screen, so double entry guards against entering a different
password than you intend (if the two passwords do not match, no entry
is generated).

The preceding command causes the following line to be added to
`/etc/mysqlmanager.passwd':

     mike:*BBF1F551DD9DD96A01E66EC7DDC073911BAD17BA

Beginning with MySQL 5.1.12, the `--passwd' option is renamed to
`--print-password-line' and there are several other options for
managing user accounts from the command line. For example, the
`--username' and `--password' options are available on the command line
for specifying the username and password for an account entry. You can
use them to generate an entry with no prompting like this (type the
command on a single line):

     shell> mysqlmanager --print-password-line
              --username=mike --password=mikepass >> /etc/mysqlmanager.passwd

If you omit the `--username' or `--password' option, Instance Manager
prompts for the required value.

`--print-password-line' causes Instance Manager to send the resulting
account entry to its output, which you can append to the password file.
The following list describes other account-management options that
cause Instance Manager to operate directly on the password file. (These
options make Instance Manager scriptable for account-management
purposes.)  For operations on the password file to succeed, the file
must exist and it must be accessible by Instance Manager. (The
exception is `--clean-password-file', which creates the file if it does
not exist. Alternatively, if there is no password file, manually create
it as an empty file and ensure that its ownership and access modes
allow it to be read and written by Instance Manager.) The default
password file is used unless you specify a `--password-file' option.

To ensure consistent treatment of the password file, it should be owned
by the system account that you use for running Instance Manager to
manage server instances, and you should invoke it from that account
when you use it to manage accounts in the password file.

   * Create a new user:

          mysqlmanager --add-user --username=USER_NAME [--password=PASSWORD]

     This command adds a new entry with the given username and password
     to the password file. The `--username' (or `-u') option is
     required. `mysqlmanager' prompts for the password if it is not
     given on the command line with the `--password' (or `-p') option.
     The command fails if the user already exists.

   * Drop an existing user:

          mysqlmanager --drop-user --username=USER_NAME

     This command removes the entry with the given username from the
     password file. The username is required. The command fails if the
     user does not exist.

   * Change the password for an existing user:

          mysqlmanager --edit-user --username=USER_NAME [--password=PASSWORD]

     This command changes the given user's password in the password
     file. The username is required.  `mysqlmanager' prompts for the
     password it is not given on the command line. The command fails if
     the user does not exist.

   * List existing users:

          mysqlmanager --list-users

     This command lists the usernames of the accounts in the password
     file.

   * Check the password file:

          mysqlmanager --check-password-file

     This command performs a consistency and validity check of the
     password file. The command fails if there is something wrong with
     the file.

   * Empty the password file:

          mysqlmanager --clean-password-file

     This command empties the password file, which has the effect of
     dropping all users listed in it. The option creates the password
     file if it does not exist, so it can be used to initialize a new
     password file to be used for other account-management operations.
     Take care not to use this option to reinitialize a file containing
     accounts that you do not want to drop.


File: manual.info,  Node: instance-manager-security-monitoring,  Next: instance-manager-security,  Prev: instance-manager-security-passwords,  Up: instance-manager

4.6.9.5 MySQL Server Instance Status Monitoring
...............................................

*Important*:

MySQL Instance Manager has been deprecated and is removed in MySQL 6.0.

To monitor the status of each guarded server instance, the MySQL
Instance Manager attempts to connect to the instance at regular
intervals using the `MySQL_Instance_Manager@localhost' user account
with a password of `check_connection'.

You are _not_ required to create this account for MySQL Server; in
fact, it is expected that it will not exist. Instance Manager can tell
that a server is operational if the server accepts the connection
attempt but refuses access for the account by returning a login error.
However, these failed connection attempts are logged by the server to
its general query log (see *Note query-log::).

Instance Manager also attempts a connection to nonguarded server
instances when you use the `SHOW INSTANCES' or `SHOW INSTANCE STATUS'
command. This is the only status monitoring done for nonguarded
instances.

Instance Manager knows if a server instance fails at startup because it
receives a status from the attempt. For an instance that starts but
later crashes, Instance Manager receives a signal because it is the
parent process of the instance.

Beginning with MySQL 5.1.12, Instance Manager tracks instance states so
that it can determine which commands are allowed for each instance. For
example, commands that modify an instance's configuration are allowed
only while the instance is offline.

Each instance is in one of the states described in the following table.
Guarded instances can be in any of the states. Nonguarded instances can
only be offline or online. Instance state information is displayed in
the `status' column of the `SHOW INSTANCES' and `SHOW INSTANCE STATUS'
commands.

*State*     *Meaning*
`offline'   The instance has not been started and is not running.
`starting'  The instance is starting (initializing). Nonguarded
            instances cannot be in this state. A nonguarded instance
            goes directly from offline to online.
`stopping'  The instance is stopping. Nonguarded instances cannot be in
            this state.  A nonguarded instance goes directly from online
            to offline, or stays offline if startup fails.
`online'    The instance has started and is running.
`failed'    The instance was online but it crashed and is being
            restarted by Instance Manager, or else the instance failed
            to start at all and Instance Manager is again attempting to
            start it. Nonguarded instances cannot be in this state.
`crashed'   Instance Manager failed to start the instance after several
            attempts.  (Instance Manager will try again later.)
            Nonguarded instances cannot be in this state.
`abandoned' Instance Manager was not able to start the instance, has
            given up, and will make no further attempts until instructed
            otherwise. To tell Instance Manager to try again, you must
            first use `STOP INSTANCE' to put the instance in offline
            state, and then use `START INSTANCE' to start the instance.
            If it is necessary to make configuration changes for the
            instance, you must do so after putting the instance offline
            and before starting it. (Instance Manager accepts
            configuration-changing commands only for offline instances.)
            Nonguarded instances cannot be in this state.


File: manual.info,  Node: instance-manager-security,  Next: instance-manager-commands,  Prev: instance-manager-security-monitoring,  Up: instance-manager

4.6.9.6 Connecting to MySQL Instance Manager
............................................

*Important*:

MySQL Instance Manager has been deprecated and is removed in MySQL 6.0.

After you set up a password file for the MySQL Instance Manager and
Instance Manager is running, you can connect to it. The MySQL
client-server protocol is used to communicate with the Instance
Manager. For example, you can connect to it using the standard `mysql'
client program:

     shell> mysql --port=2273 --host=im.example.org --user=mysql --password

Instance Manager supports the version of the MySQL client-server
protocol used by the client tools and libraries distributed with MySQL
4.1 or later, so other programs that use the MySQL C API also can
connect to it.


File: manual.info,  Node: instance-manager-commands,  Prev: instance-manager-security,  Up: instance-manager

4.6.9.7 MySQL Instance Manager Commands
.......................................

*Important*:

MySQL Instance Manager has been deprecated and is removed in MySQL 6.0.

After you connect to MySQL Instance Manager, you can issue commands.
The following general principles apply to Instance Manager command
execution:

   * Commands that take an instance name fail if the name is not a
     valid instance name.

   * Commands that take an instance name (other than `CREATE INSTANCE')
     fail if the instance does not exist.

   * As of MySQL 5.1.12, commands for an instance require that the
     instance be in an appropriate state. You cannot configure or start
     an instance that is not offline. You cannot start an instance that
     is online.

   * Instance Manager maintains information about instance
     configuration in an internal (in-memory) cache. Initially, this
     information comes from the configuration file if it exists, but
     some commands change the configuration of an instance. Commands
     that modify the configuration file fail if the file does not exist
     or is not accessible to Instance Manager.

     As of MySQL 5.1.12, configuration-changing commands modify both
     the in-memory cache and the server instance section recorded in
     the configuration file to maintain consistency between them. For
     this to occur, the instance must be offline and the configuration
     file must be accessible and not malformed. If the configuration
     file cannot be updated, the command fails and the cache remains
     unchanged.

   * On Windows, the standard file is `my.ini' in the directory where
     Instance Manager is installed. On Unix, the standard configuration
     file is `/etc/my.cnf'. To specify a different configuration file,
     start Instance Manager with the `--defaults-file' option.

   * If a `[mysqld]' instance section exists in the configuration file,
     it must not contain any Instance Manager-specific options (see
     *Note instance-manager-configuration-files::).  Therefore, you
     must not add any of these options if you change the configuration
     for an instance named `mysqld'.

The following list describes the commands that Instance Manager
accepts, with examples.

   * `CREATE INSTANCE INSTANCE_NAME [OPTION_NAME[=OPTION_VALUE], ...]'

     This command configures a new instance by creating an
     `[INSTANCE_NAME]' section in the configuration file. The command
     fails if INSTANCE_NAME is not a valid instance name or the
     instance already exists.

     The created section instance is empty if no options are given.
     Otherwise, the options are added to the section.  Options should
     be given in the same format used when you write options in option
     files. (See *Note option-files:: for a description of the
     allowable syntax.) If you specify multiple options, separate them
     by commas.

     For example, to create an instance section named `[mysqld98]', you
     might write something like this were you to modify the
     configuration file directly:

          [mysqld98]
          basedir=/var/mysql98

     To achieve the same effect via `CREATE INSTANCE', issue this
     command to Instance Manager:

          mysql> CREATE INSTANCE mysqld98 basedir="/var/mysql98";
          Query OK, 0 rows affected (0,00 sec)

     `CREATE INSTANCE' creates the instance but does not start it.

     If the instance name is the (deprecated) name `mysqld', the option
     list cannot include any options that are specific to Instance
     Manager, such as `nonguarded' (see *Note
     instance-manager-configuration-files::).

     This command was added in MySQL 5.1.12.

   * `DROP INSTANCE INSTANCE_NAME'

     This command removes the configuration for INSTANCE_NAME from the
     configuration file.

          mysql> DROP INSTANCE mysqld98;
          Query OK, 0 rows affected (0,00 sec)

     The command fails if INSTANCE_NAME is not a valid instance name,
     the instance does not exist, or is not offline.

     This command was added in MySQL 5.1.12.

   * `START INSTANCE INSTANCE_NAME'

     This command attempts to start an offline instance. The command is
     asynchronous; it does not wait for the instance to start.

          mysql> START INSTANCE mysqld4;
          Query OK, 0 rows affected (0,00 sec)

   * `STOP INSTANCE INSTANCE_NAME'

     This command attempts to stop an instance. The command is
     synchronous; it waits for the instance to stop.

          mysql> STOP INSTANCE mysqld4;
          Query OK, 0 rows affected (0,00 sec)

   * `SHOW INSTANCES'

     Shows the names and status of all loaded instances.

          mysql> SHOW INSTANCES;
          +---------------+---------+
          | instance_name | status  |
          +---------------+---------+
          | mysqld3       | offline |
          | mysqld4       | online  |
          | mysqld2       | offline |
          +---------------+---------+

   * `SHOW INSTANCE STATUS INSTANCE_NAME'

     Shows status and version information for an instance.

          mysql> SHOW INSTANCE STATUS mysqld3;
          +---------------+--------+---------+
          | instance_name | status | version |
          +---------------+--------+---------+
          | mysqld3       | online | unknown |
          +---------------+--------+---------+

   * `SHOW INSTANCE OPTIONS INSTANCE_NAME'

     Shows the options used by an instance.

          mysql> SHOW INSTANCE OPTIONS mysqld3;
          +---------------+---------------------------------------------------+
          | option_name   | value                                             |
          +---------------+---------------------------------------------------+
          | instance_name | mysqld3                                           |
          | mysqld-path   | /home/cps/mysql/trees/mysql-4.1/sql/mysqld        |
          | port          | 3309                                              |
          | socket        | /tmp/mysql.sock3                                  |
          | pid-file      | hostname.pid3                                     |
          | datadir       | /home/cps/mysql_data/data_dir1/                   |
          | language      | /home/cps/mysql/trees/mysql-4.1/sql/share/english |
          +---------------+---------------------------------------------------+

   * `SHOW INSTANCE_NAME LOG FILES'

     The command lists all log files used by the instance. The result
     set contains the path to the log file and the log file size. If no
     log file path is specified in the instance section of the
     configuration file (for example, `log=/var/mysql.log'), the
     Instance Manager tries to guess its placement. If Instance Manager
     is unable to guess the log file placement you should specify the
     log file location explicitly by using a log option in the
     appropriate instance section of the configuration file.

          mysql> SHOW mysqld LOG FILES;
          +-------------+------------------------------------+----------+
          | Logfile     | Path                               | Filesize |
          +-------------+------------------------------------+----------+
          | ERROR LOG   | /home/cps/var/mysql/owlet.err      | 9186     |
          | GENERAL LOG | /home/cps/var/mysql/owlet.log      | 471503   |
          | SLOW LOG    | /home/cps/var/mysql/owlet-slow.log | 4463     |
          +-------------+------------------------------------+----------+

     `SHOW ... LOG FILES' displays information only about log files. If
     a server instance uses log tables (see *Note log-tables::), no
     information about those tables is shown.

     Log options are described in *Note server-options::.

   * `SHOW INSTANCE_NAME LOG {ERROR | SLOW | GENERAL}
     SIZE[,OFFSET_FROM_END]'

     This command retrieves a portion of the specified log file.
     Because most users are interested in the latest log messages, the
     SIZE parameter defines the number of bytes to retrieve from the
     end of the log. To retrieve data from the middle of the log file,
     specify the optional OFFSET_FROM_END parameter. The following
     example retrieves 21 bytes of data, starting 23 bytes before the
     end of the log file and ending 2 bytes before the end:

          mysql> SHOW mysqld LOG GENERAL 21, 2;
          +---------------------+
          | Log                 |
          +---------------------+
          | using password: YES |
          +---------------------+

   * `SET INSTANCE_NAME.OPTION_NAME[=OPTION_VALUE]'

     This command edits the specified instance's configuration section
     to change or add instance options. The option is added to the
     section is it is not already present.  Otherwise, the new setting
     replaces the existing one.

          mysql> SET mysqld2.port=3322;
          Query OK, 0 rows affected (0.00 sec)

     As of MySQL 5.1.12, you can specify multiple options (separated by
     commas), and `SET' can be used only for offline instances. Each
     option must indicate the instance name:

          mysql> SET mysqld2.port=3322, mysqld3.nonguarded;
          Query OK, 0 rows affected (0.00 sec)

     Before MySQL 5.1.12, only a single option can be specified.  Also,
     changes made to the configuration file do not take effect until
     the MySQL server is restarted. In addition, these changes are not
     stored in the instance manager's local cache of instance settings
     until a `FLUSH INSTANCES' command is executed.

   * `UNSET INSTANCE_NAME.OPTION_NAME'

     This command removes an option from an instance's configuration
     section.

          mysql> UNSET mysqld2.port;
          Query OK, 0 rows affected (0.00 sec)

     As of MySQL 5.1.12, you can specify multiple options (separated by
     commas), and `UNSET' can be used only for offline instances. Each
     option must indicate the instance name:

          mysql> UNSET mysqld2.port, mysqld4.nonguarded;
          Query OK, 0 rows affected (0.00 sec)

     Before MySQL 5.1.12, only a single option can be specified.  Also,
     changes made to the configuration file do not take effect until
     the MySQL server is restarted. In addition, these changes are not
     stored in the instance manager's local cache of instance settings
     until a `FLUSH INSTANCES' command is executed.

   * `FLUSH INSTANCES'

     As of MySQL 5.1.12, `FLUSH INSTANCES' cannot be used unless all
     instances are offline. The command causes Instance Manager to
     reread the configuration file, update its in-memory configuration
     cache, and start any guarded instances.

     Before MySQL 5.1.12, this command forces Instance Manager reread
     the configuration file and to refresh internal structures. This
     command should be performed after editing the configuration file.
     The command does not restart instances.

          mysql> FLUSH INSTANCES;
          Query OK, 0 rows affected (0.04 sec)


File: manual.info,  Node: mysql-convert-table-format,  Next: mysql-find-rows,  Prev: instance-manager,  Up: programs-admin-utils

4.6.10 `mysql_convert_table_format' -- Convert Tables to Use a Given Storage Engine
-----------------------------------------------------------------------------------

`mysql_convert_table_format' converts the tables in a database to use a
particular storage engine (`MyISAM' by default).
`mysql_convert_table_format' is written in Perl and requires that the
`DBI' and `DBD::mysql' Perl modules be installed (see *Note
perl-support::).

The results may assist you in determining which queries result in table
scans and where it would be beneficial to add indexes to your tables.

Invoke `mysql_convert_table_format' like this:

     shell> mysql_convert_table_format [OPTIONS]DB_NAME

The DB_NAME argument indicates the database containing the tables to be
converted.

`mysql_convert_table_format' understands the options described in the
following list.

   *  `--help', `-?'

     Display a help message and exit.

   *  `--force'

     Continue even if errors occur.

   *  `--host=HOST_NAME', `-h HOST_NAME'

     Connect to the MySQL server on the given host.

   *  `--password=PASSWORD', `-p PASSWORD'

     The password to use when connecting to the server. Note that the
     password value is not optional for this option, unlike for other
     MySQL programs. You can use an option file to avoid giving the
     password on the command line.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security::.

   *  `--port=PORT_NUM'

     The TCP/IP port number to use for the connection.

   *  `--socket=PATH', `-S PATH'

     For connections to `localhost', the Unix socket file to use.

   *  `--type=ENGINE_NAME'

     Specify the storage engine that the tables should be converted to
     use. The default is `MyISAM' if this option is not given.

     MySQL Enterprise

     For expert advice on choosing the optimum storage engine,
     subscribe to the MySQL Enterprise Monitor. For more information see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   *  `--user=USER_NAME', `-u USER_NAME'

     The MySQL username to use when connecting to the server.

   *  `--verbose'

     Verbose mode. Print more information about what the program does.

   *  `--version'

     Display version information and exit.


File: manual.info,  Node: mysql-find-rows,  Next: mysql-fix-extensions,  Prev: mysql-convert-table-format,  Up: programs-admin-utils

4.6.11 `mysql_find_rows' -- Extract SQL Statements from Files
-------------------------------------------------------------

`mysql_find_rows' reads files containing SQL statements and extracts
statements that match a given regular expression or that contain `USE
DB_NAME' or `SET' statements. The utility was written for use with
update log files, but it can be used with other files that contain SQL
statements.

Invoke `mysql_find_rows' like this:

     shell> mysql_find_rows [OPTIONS] [FILE_NAME ...]

Each FILE_NAME argument should be the name of file containing SQL
statements. If no filenames are given, `mysql_find_rows' reads the
standard input.

Examples:

     mysql_find_rows --regexp=problem_table --rows=20 < update.log
     mysql_find_rows --regexp=problem_table  update-log.1 update-log.2

`mysql_find_rows' supports the following options:

   *  `--help', `--Information'

     Display a help message and exit.

   *  `--regexp=PATTERN'

     Display queries that match the pattern.

   *  `--rows=N'

     Quit after displaying N queries.

   *  `--skip-use-db'

     Do not include `USE DB_NAME' statements in the output.

   *  `--start_row=N'

     Start output from this row.


File: manual.info,  Node: mysql-fix-extensions,  Next: mysql-setpermission,  Prev: mysql-find-rows,  Up: programs-admin-utils

4.6.12 `mysql_fix_extensions' -- Normalize Table Filename Extensions
--------------------------------------------------------------------

`mysql_fix_extensions' converts the extensions for `MyISAM' (or `ISAM')
table files to their canonical forms. It looks for files with
extensions matching any lettercase variant of `.frm', `.myd', `.myi',
`.isd', and `.ism' and renames them to have extensions of `.frm',
`.MYD', `.MYI', `.ISD', and `.ISM', respectively. This can be useful
after transferring the files from a system with case-insensitive
filenames (such as Windows) to a system with case-sensitive filenames.

Invoke `mysql_fix_extensions' like this, where DATA_DIR is the pathname
to the MySQL data directory.

     shell> mysql_fix_extensions DATA_DIR


File: manual.info,  Node: mysql-setpermission,  Next: mysql-waitpid,  Prev: mysql-fix-extensions,  Up: programs-admin-utils

4.6.13 `mysql_setpermission' -- Interactively Set Permissions in Grant Tables
-----------------------------------------------------------------------------

`mysql_setpermission' is a Perl script that was originally written and
contributed by Luuk de Boer. It interactively sets permissions in the
MySQL grant tables.  `mysql_setpermission' is written in Perl and
requires that the `DBI' and `DBD::mysql' Perl modules be installed (see
*Note perl-support::).

Invoke `mysql_setpermission' like this:

     shell> mysql_setpermission [OPTIONS]

OPTIONS should be either `--help' to display the help message, or
options that indicate how to connect to the MySQL server. The account
used when you connect determines which permissions you have when
attempting to modify existing permissions in the grant tables.

`mysql_setpermissions' also reads options from the `[client]' and
`[perl]' groups in the `.my.cnf' file in your home directory, if the
file exists.

`mysql_setpermission' understands the following options:

   *  `--help'

     Display a help message and exit.

   *  `--host=HOST_NAME'

     Connect to the MySQL server on the given host.

   *  `--password=PASSWORD'

     The password to use when connecting to the server. Note that the
     password value is not optional for this option, unlike for other
     MySQL programs. You can use an option file to avoid giving the
     password on the command line.

     Specifying a password on the command line should be considered
     insecure. See *Note password-security::.

   *  `--port=PORT_NUM'

     The TCP/IP port number to use for the connection.

   *  `--socket=PATH'

     For connections to `localhost', the Unix socket file to use.

   *  `--user=USER_NAME'

     The MySQL username to use when connecting to the server.


File: manual.info,  Node: mysql-waitpid,  Next: mysql-zap,  Prev: mysql-setpermission,  Up: programs-admin-utils

4.6.14 `mysql_waitpid' -- Kill Process and Wait for Its Termination
-------------------------------------------------------------------

`mysql_waitpid' signals a process to terminate and waits for the
process to exit. It uses the `kill()' system call and Unix signals, so
it runs on Unix and Unix-like systems.

Invoke `mysql_waitpid' like this:

     shell> mysql_waitpid [OPTIONS] PID WAIT_TIME

`mysql_waitpid' sends signal 0 to the process identified by PID and
waits up to WAIT_TIME seconds for the process to terminate. PID and
WAIT_TIME must be positive integers.

If process termination occurs within the wait time or the process does
not exist, `mysql_waitpid' returns 0. Otherwise, it returns 1.

If the `kill()' system call cannot handle signal 0, `mysql_waitpid()'
uses signal 1 instead.

`mysql_waitpid' understands the following options:

   *  `--help', `-?', `-I'

     Display a help message and exit.

   *  `--verbose', `-v'

     Verbose mode. Display a warning if signal 0 could not be used and
     signal 1 is used instead.

   *  `--version', `-V'

     Display version information and exit.


File: manual.info,  Node: mysql-zap,  Prev: mysql-waitpid,  Up: programs-admin-utils

4.6.15 `mysql_zap' -- Kill Processes That Match a Pattern
---------------------------------------------------------

`mysql_zap' kills processes that match a pattern. It uses the `ps'
command and Unix signals, so it runs on Unix and Unix-like systems.

Invoke `mysql_zap' like this:

     shell> mysql_zap [-SIGNAL] [-?Ift] PATTERN

A process matches if its output line from the `ps' command contains the
pattern. By default, `mysql_zap' asks for confirmation for each
process. Respond `y' to kill the process, or `q' to exit `mysql_zap'.
For any other response, `mysql_zap' does not attempt to kill the
process.

If the `-SIGNAL' option is given, it specifies the name or number of
the signal to send to each process. Otherwise, `mysql_zap' tries first
with `TERM' (signal 15) and then with `KILL' (signal 9).

`mysql_zap' understands the following additional options:

   *  `--help', `-?', `-I'

     Display a help message and exit.

   *  `-f'

     Force mode. `mysql_zap' attempts to kill each process without
     confirmation.

   *  `-t'

     Test mode. Display information about each process but do not kill
     it.


File: manual.info,  Node: programs-development,  Next: programs-miscellaneous,  Prev: programs-admin-utils,  Up: programs

4.7 MySQL Program Development Utilities
=======================================

* Menu:

* msql2mysql::                   `msql2mysql' --- Convert mSQL Programs for Use with MySQL
* mysql-config::                 `mysql_config' --- Get Compile Options for Compiling Clients
* my-print-defaults::            `my_print_defaults' --- Display Options from Option Files
* resolve-stack-dump::           `resolve_stack_dump' --- Resolve Numeric Stack Trace Dump to Symbols

This section describes some utilities that you may find useful when
developing MySQL programs.

In shell scripts, you can use the `my_print_defaults' program to parse
option files and see what options would be used by a given program. The
following example shows the output that `my_print_defaults' might
produce when asked to show the options found in the `[client]' and
`[mysql]' groups:

     shell> my_print_defaults client mysql
     --port=3306
     --socket=/tmp/mysql.sock
     --no-auto-rehash

*Note_for developers*: Option file handling is implemented in the C
client library simply by processing all options in the appropriate
group or groups before any command-line arguments. This works well for
programs that use the last instance of an option that is specified
multiple times. If you have a C or C++ program that handles multiply
specified options this way but that doesn't read option files, you need
add only two lines to give it that capability. Check the source code of
any of the standard MySQL clients to see how to do this.

Several other language interfaces to MySQL are based on the C client
library, and some of them provide a way to access option file contents.
These include Perl and Python. For details, see the documentation for
your preferred interface.


File: manual.info,  Node: msql2mysql,  Next: mysql-config,  Prev: programs-development,  Up: programs-development

4.7.1 `msql2mysql' -- Convert mSQL Programs for Use with MySQL
--------------------------------------------------------------

Initially, the MySQL C API was developed to be very similar to that for
the mSQL database system. Because of this, mSQL programs often can be
converted relatively easily for use with MySQL by changing the names of
the C API functions.

The `msql2mysql' utility performs the conversion of mSQL C API function
calls to their MySQL equivalents. `msql2mysql' converts the input file
in place, so make a copy of the original before converting it. For
example, use `msql2mysql' like this:

     shell> cp client-prog.c client-prog.c.orig
     shell> msql2mysql client-prog.c
     client-prog.c converted

Then examine `client-prog.c' and make any post-conversion revisions
that may be necessary.

`msql2mysql' uses the `replace' utility to make the function name
substitutions. See *Note replace-utility::.


File: manual.info,  Node: mysql-config,  Next: my-print-defaults,  Prev: msql2mysql,  Up: programs-development

4.7.2 `mysql_config' -- Get Compile Options for Compiling Clients
-----------------------------------------------------------------

`mysql_config' provides you with useful information for compiling your
MySQL client and connecting it to MySQL.

`mysql_config' supports the following options:

   * `--cflags'

     Compiler flags to find include files and critical compiler flags
     and defines used when compiling the `libmysqlclient' library. The
     options returned are tied to the specific compiler that was used
     when the library was created and might clash with the settings for
     your own compiler. Use `--include' for more portable options that
     contain only include paths.

   * `--include'

     Compiler options to find MySQL include files.

   * `--libmysqld-libs', `--embedded'

     Libraries and options required to link with the MySQL embedded
     server.

   * `--libs'

     Libraries and options required to link with the MySQL client
     library.

   * `--libs_r'

     Libraries and options required to link with the thread-safe MySQL
     client library.

   * `--plugindir'

     The default plugin directory pathname, defined when configuring
     MySQL. This option was added in MySQL 5.1.24.

   * `--port'

     The default TCP/IP port number, defined when configuring MySQL.

   * `--socket'

     The default Unix socket file, defined when configuring MySQL.

   * `--version'

     Version number for the MySQL distribution.

If you invoke `mysql_config' with no options, it displays a list of all
options that it supports, and their values:

     shell> mysql_config
     Usage: /usr/local/mysql/bin/mysql_config [options]
     Options:
       --cflags         [-I/usr/local/mysql/include/mysql -mcpu=pentiumpro]
       --include        [-I/usr/local/mysql/include/mysql]
       --libs           [-L/usr/local/mysql/lib/mysql -lmysqlclient -lz
                         -lcrypt -lnsl -lm -L/usr/lib -lssl -lcrypto]
       --libs_r         [-L/usr/local/mysql/lib/mysql -lmysqlclient_r
                         -lpthread -lz -lcrypt -lnsl -lm -lpthread]
       --socket         [/tmp/mysql.sock]
       --port           [3306]
       --version        [4.0.16]
       --libmysqld-libs [-L/usr/local/mysql/lib/mysql -lmysqld -lpthread -lz
                         -lcrypt -lnsl -lm -lpthread -lrt]

You can use `mysql_config' within a command line to include the value
that it displays for a particular option. For example, to compile a
MySQL client program, use `mysql_config' as follows:

     shell> CFG=/usr/local/mysql/bin/mysql_config
     shell> sh -c "gcc -o progname `$CFG --include` progname.c `$CFG --libs`"

When you use `mysql_config' this way, be sure to invoke it within
backtick (```'') characters. That tells the shell to execute it and
substitute its output into the surrounding command.


File: manual.info,  Node: my-print-defaults,  Next: resolve-stack-dump,  Prev: mysql-config,  Up: programs-development

4.7.3 `my_print_defaults' -- Display Options from Option Files
--------------------------------------------------------------

`my_print_defaults' displays the options that are present in option
groups of option files. The output indicates what options will be used
by programs that read the specified option groups. For example, the
`mysqlcheck' program reads the `[mysqlcheck]' and `[client]' option
groups. To see what options are present in those groups in the standard
option files, invoke `my_print_defaults' like this:

     shell> my_print_defaults mysqlcheck client
     --user=myusername
     --password=secret
     --host=localhost

The output consists of options, one per line, in the form that they
would be specified on the command line.

`my_print_defaults' understands the following options:

   *  `--help', `-?'

     Display a help message and exit.

   *  `--config-file=FILE_NAME',

     `--defaults-file=FILE_NAME', `-c FILE_NAME'

     Read only the given option file.

   *  `--debug=DEBUG_OPTIONS, -# DEBUG_OPTIONS'

     Write a debugging log. The DEBUG_OPTIONS string often is
     `'d:t:o,FILE_NAME''.  The default is
     `'d:t:o,/tmp/my_print_defaults.trace''.

   *  `--defaults-extra-file=FILE_NAME',

     `--extra-file=FILE_NAME', `-e FILE_NAME'

     Read this option file after the global option file but (on Unix)
     before the user option file.

   *  `--defaults-group-suffix=SUFFIX', `-g SUFFIX'

     In addition to the groups named on the command line, read groups
     that have the given suffix.

   *  `--no-defaults', `-n'

     Return an empty string.

   *  `--verbose', `-v'

     Verbose mode. Print more information about what the program does.

   *  `--version', `-V'

     Display version information and exit.


File: manual.info,  Node: resolve-stack-dump,  Prev: my-print-defaults,  Up: programs-development

4.7.4 `resolve_stack_dump' -- Resolve Numeric Stack Trace Dump to Symbols
-------------------------------------------------------------------------

`resolve_stack_dump' resolves a numeric stack dump to symbols.

Invoke `resolve_stack_dump' like this:

     shell> resolve_stack_dump [OPTIONS] SYMBOLS_FILE [NUMERIC_DUMP_FILE]

The symbols file should include the output from the `nm --numeric-sort
mysqld' command. The numeric dump file should contain a numeric stack
track from `mysqld'. If no numeric dump file is named on the command
line, the stack trace is read from the standard input.

`resolve_stack_dump' understands the options described in the following
list.

   *  `--help', `-h'

     Display a help message and exit.

   *  `--numeric-dump-file=FILE_NAME', `-n FILE_NAME'

     Read the stack trace from the given file.

   *  `--symbols-file=FILE_NAME', `-s FILE_NAME'

     Use the given symbols file.

   *  `--version', `-V'

     Display version information and exit.


File: manual.info,  Node: programs-miscellaneous,  Prev: programs-development,  Up: programs

4.8 Miscellaneous Programs
==========================

* Menu:

* perror::                       `perror' --- Explain Error Codes
* replace-utility::              `replace' --- A String-Replacement Utility
* resolveip::                    `resolveip' --- Resolve Hostname to IP Address or Vice Versa


File: manual.info,  Node: perror,  Next: replace-utility,  Prev: programs-miscellaneous,  Up: programs-miscellaneous

4.8.1 `perror' -- Explain Error Codes
-------------------------------------

For most system errors, MySQL displays, in addition to an internal text
message, the system error code in one of the following styles:

     message ... (errno: #)
     message ... (Errcode: #)

You can find out what the error code means by examining the
documentation for your system or by using the `perror' utility.

`perror' prints a description for a system error code or for a storage
engine (table handler) error code.

Invoke `perror' like this:

     shell> perror [OPTIONS] ERRORCODE ...

Example:

     shell> perror 13 64
     OS error code  13:  Permission denied
     OS error code  64:  Machine is not on the network

To obtain the error message for a MySQL Cluster error code, invoke
`perror' with the `--ndb' option:

     shell> perror --ndb ERRORCODE

Note that the meaning of system error messages may be dependent on your
operating system. A given error code may mean different things on
different operating systems.

`perror' supports the following options:

   *  `--help', `--info', `-I', `-?'

     Display a help message and exit.

   *  `--ndb'

     Print the error message for a MySQL Cluster error code.

   *  `--silent', `-s'

     Silent mode. Print only the error message.

   *  `--verbose', `-v'

     Verbose mode. Print error code and message. This is the default
     behavior.

   *  `--version', `-V'

     Display version information and exit.


File: manual.info,  Node: replace-utility,  Next: resolveip,  Prev: perror,  Up: programs-miscellaneous

4.8.2 `replace' -- A String-Replacement Utility
-----------------------------------------------

The `replace' utility program changes strings in place in files or on
the standard input.

Invoke `replace' in one of the following ways:

     shell> replace FROM TO [FROM TO] ... -- FILE_NAME [FILE_NAME] ...
     shell> replace FROM TO [FROM TO] ... < FILE_NAME

FROM represents a string to look for and TO represents its replacement.
There can be one or more pairs of strings.

Use the `--' option to indicate where the string-replacement list ends
and the filenames begin. In this case, any file named on the command
line is modified in place, so you may want to make a copy of the
original before converting it. REPLACE prints a message indicating
which of the input files it actually modifies.

If the `--' option is not given, `replace' reads the standard input and
writes to the standard output.

`replace' uses a finite state machine to match longer strings first. It
can be used to swap strings. For example, the following command swaps
`a' and `b' in the given files, `file1' and `file2':

     shell> replace a b b a -- file1 file2 ...

The `replace' program is used by `msql2mysql'. See *Note msql2mysql::.

`replace' supports the following options:

   *  `-?', `-I'

     Display a help message and exit.

   *  `-#DEBUG_OPTIONS'

     Enable debugging.

   *  `-s'

     Silent mode. Print less information what the program does.

   *  `-v'

     Verbose mode. Print more information about what the program does.

   *  `-V'

     Display version information and exit.


File: manual.info,  Node: resolveip,  Prev: replace-utility,  Up: programs-miscellaneous

4.8.3 `resolveip' -- Resolve Hostname to IP Address or Vice Versa
-----------------------------------------------------------------

The `resolveip' utility resolves hostnames to IP addresses and vice
versa.

Invoke `resolveip' like this:

     shell> resolveip [OPTIONS] {HOST_NAME|IP-ADDR} ...

`resolveip' understands the options described in the following list.

   *  `--help', `-info', `-?', `-I'

     Display a help message and exit.

   *  `--silent', `-s'

     Silent mode. Produce less output.

   *  `--version', `-V'

     Display version information and exit.


File: manual.info,  Node: server-administration,  Next: backup-and-recovery,  Prev: programs,  Up: Top

5 MySQL Server Administration
*****************************

* Menu:

* mysqld-server::                The MySQL Server
* log-files::                    MySQL Server Logs
* security::                     General Security Issues
* privilege-system::             The MySQL Access Privilege System
* user-account-management::      MySQL User Account Management
* multiple-servers::             Running Multiple MySQL Servers on the Same Machine

MySQL Server (`mysqld') is the main program that does most of the work
in a MySQL installation. This section provides an overview of MySQL
Server and covers topics that deal with administering a MySQL
installation:

   * Configuring the server

   * The server log files

   * Managing user accounts


File: manual.info,  Node: mysqld-server,  Next: log-files,  Prev: server-administration,  Up: server-administration

5.1 The MySQL Server
====================

* Menu:

* mysqld-option-tables::         Option and Variable Reference
* server-options::               Command Options
* server-system-variables::      System Variables
* server-session-variables::     Session System Variables
* using-system-variables::       Using System Variables
* server-status-variables::      Status Variables
* server-sql-mode::              SQL Modes
* server-side-help-support::     Server-Side Help
* server-signal-response::       Server Response to Signals
* server-shutdown::              The Shutdown Process

`mysqld' is the MySQL server. The following discussion covers these
MySQL server configuration topics:

   * Startup options that the server supports

   * Server system variables

   * Server status variables

   * How to set the server SQL mode

   * The server shutdown process

*Note*:

Not all storage engines are supported by all MySQL server binaries and
configurations. To find out how to determine which storage engines are
supported by your MySQL server installation, see *Note show-engines::.


File: manual.info,  Node: mysqld-option-tables,  Next: server-options,  Prev: mysqld-server,  Up: mysqld-server

5.1.1 Option and Variable Reference
-----------------------------------

The following table provides a list of all the command line options,
server and status variables applicable within `mysqld'.

The table lists command-line options (Cmd-line), options valid in
configuration files (Option file), server system variables (System
Var), and status variables (Status var) in one unified list, with
notification of where each option/variable is valid.  If a server
option set on the command line or in an option file differs from the
name of the corresponding server system or status variable, the
variable name is noted immediately below the corresponding option. For
status variables, the scope of the variable is shown (Scope) as either
global, session, or both.  Please see the corresponding sections for
details on setting and using the options and variables. Where
appropriate, a direct link to further information on the item as
available.

*Note*:

This table is part of an ongoing process to expand and simplify the
information provided on these elements. Further improvements to the
table, and corresponding descriptions will be applied over the coming
months.

*Name*                        *Cmd-Line*                                                 *Option file*                                              *System Var*                                               *Status Var*                                               *Var Scope*                                                *Dynamic*
Aborted_clients                                                                                                                                                                                                Yes                                                        Both                                                       No
Aborted_connects                                                                                                                                                                                               Yes                                                        Global                                                     No
abort-slave-event-count       Yes                                                        Yes                                                                                                                                                                                                                                         
allow-suspicious-udfs         Yes                                                        Yes                                                                                                                                                                                                                                         
ansi                          Yes                                                        Yes                                                                                                                                                                                                                                         
autocommit                                                                                                                                          Yes                                                                                                                   Session                                                    Yes
auto-increment-increment      Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Both                                                       Yes
auto_increment_increment                                                                                                                                                                                                                                                                                                             
auto-increment-offset         Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Both                                                       Yes
auto_increment_offset                                                                                                                                                                                                                                                                                                                
automatic_sp_privileges                                                                                                                             Yes                                                                                                                   Global                                                     Yes
back_log                      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
basedir                       Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
big-tables                    Yes                                                        Yes                                                                                                                                                                              Session                                                    Yes
- _Variable_: big_tables                                                                                                                            Yes                                                                                                                   Session                                                    Yes
bind-address                  Yes                                                        Yes                                                                                                                                                                                                                                         
Binlog_cache_disk_use                                                                                                                                                                                          Yes                                                        Both                                                       No
binlog_cache_size             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
Binlog_cache_use                                                                                                                                                                                               Yes                                                        Both                                                       No
binlog-do-db                  Yes                                                        Yes                                                                                                                                                                                                                                         
binlog-format                 Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_: binlog_format                                                                                                                         Yes                                                                                                                   Both                                                       Yes
binlog-ignore-db              Yes                                                        Yes                                                                                                                                                                                                                                         
binlog-row-event-max-size     Yes                                                        Yes                                                                                                                                                                                                                                         
bootstrap                     Yes                                                        Yes                                                                                                                                                                                                                                         
bulk_insert_buffer_size       Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
Bytes_received                                                                                                                                                                                                 Yes                                                        Both                                                       No
Bytes_sent                                                                                                                                                                                                     Yes                                                        Both                                                       No
character_set_client                                                                                                                                Yes                                                                                                                   Both                                                       Yes
character-set-client-handshakeYes                                                                                                                                                                                                                                                                                                    
character_set_connection                                                                                                                            Yes                                                                                                                   Both                                                       Yes
character_set_database                                                                                                                              Yes                                                                                                                   Both                                                       Yes
character-set-filesystem      Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Both                                                       Yes
character_set_filesystem                                                                                                                                                                                                                                                                                                             
character_set_results                                                                                                                               Yes                                                                                                                   Both                                                       Yes
character-sets-dir            Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
character_sets_dir                                                                                                                                                                                                                                                                                                                   
character-set-server          Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Both                                                       Yes
character_set_server                                                                                                                                                                                                                                                                                                                 
character_set_system                                                                                                                                Yes                                                                                                                   Global                                                     No
chroot                        Yes                                                        Yes                                                                                                                                                                                                                                         
collation_connection                                                                                                                                Yes                                                                                                                   Both                                                       Yes
collation_database                                                                                                                                  Yes                                                                                                                   Both                                                       Yes
collation-server              Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Both                                                       Yes
collation_server                                                                                                                                                                                                                                                                                                                     
Com_admin_commands                                                                                                                                                                                             Yes                                                        Both                                                       No
Com_alter_db                                                                                                                                                                                                   Yes                                                        Both                                                       No
Com_alter_event                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_alter_table                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_analyze                                                                                                                                                                                                    Yes                                                        Both                                                       No
Com_backup_table                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_begin                                                                                                                                                                                                      Yes                                                        Both                                                       No
Com_call_procedure                                                                                                                                                                                             Yes                                                        Both                                                       No
Com_change_db                                                                                                                                                                                                  Yes                                                        Both                                                       No
Com_change_master                                                                                                                                                                                              Yes                                                        Both                                                       No
Com_check                                                                                                                                                                                                      Yes                                                        Both                                                       No
Com_checksum                                                                                                                                                                                                   Yes                                                        Both                                                       No
Com_commit                                                                                                                                                                                                     Yes                                                        Both                                                       No
Com_create_db                                                                                                                                                                                                  Yes                                                        Both                                                       No
Com_create_event                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_create_function                                                                                                                                                                                            Yes                                                        Both                                                       No
Com_create_index                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_create_table                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_create_user                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_dealloc_sql                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_delete                                                                                                                                                                                                     Yes                                                        Both                                                       No
Com_delete_multi                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_do                                                                                                                                                                                                         Yes                                                        Both                                                       No
Com_drop_db                                                                                                                                                                                                    Yes                                                        Both                                                       No
Com_drop_event                                                                                                                                                                                                 Yes                                                        Both                                                       No
Com_drop_function                                                                                                                                                                                              Yes                                                        Both                                                       No
Com_drop_index                                                                                                                                                                                                 Yes                                                        Both                                                       No
Com_drop_table                                                                                                                                                                                                 Yes                                                        Both                                                       No
Com_drop_user                                                                                                                                                                                                  Yes                                                        Both                                                       No
Com_execute_sql                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_flush                                                                                                                                                                                                      Yes                                                        Both                                                       No
Com_grant                                                                                                                                                                                                      Yes                                                        Both                                                       No
Com_ha_close                                                                                                                                                                                                   Yes                                                        Both                                                       No
Com_ha_open                                                                                                                                                                                                    Yes                                                        Both                                                       No
Com_ha_read                                                                                                                                                                                                    Yes                                                        Both                                                       No
Com_help                                                                                                                                                                                                       Yes                                                        Both                                                       No
Com_insert                                                                                                                                                                                                     Yes                                                        Both                                                       No
Com_insert_select                                                                                                                                                                                              Yes                                                        Both                                                       No
Com_kill                                                                                                                                                                                                       Yes                                                        Both                                                       No
Com_load                                                                                                                                                                                                       Yes                                                        Both                                                       No
Com_lock_tables                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_optimize                                                                                                                                                                                                   Yes                                                        Both                                                       No
completion_type               Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
Com_preload_keys                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_prepare_sql                                                                                                                                                                                                Yes                                                        Both                                                       No
Compression                                                                                                                                                                                                    Yes                                                        Both                                                       No
Com_purge                                                                                                                                                                                                      Yes                                                        Both                                                       No
Com_purge_before_date                                                                                                                                                                                          Yes                                                        Both                                                       No
Com_rename_table                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_repair                                                                                                                                                                                                     Yes                                                        Both                                                       No
Com_replace                                                                                                                                                                                                    Yes                                                        Both                                                       No
Com_replace_select                                                                                                                                                                                             Yes                                                        Both                                                       No
Com_reset                                                                                                                                                                                                      Yes                                                        Both                                                       No
Com_restore_table                                                                                                                                                                                              Yes                                                        Both                                                       No
Com_revoke                                                                                                                                                                                                     Yes                                                        Both                                                       No
Com_revoke_all                                                                                                                                                                                                 Yes                                                        Both                                                       No
Com_rollback                                                                                                                                                                                                   Yes                                                        Both                                                       No
Com_savepoint                                                                                                                                                                                                  Yes                                                        Both                                                       No
Com_select                                                                                                                                                                                                     Yes                                                        Both                                                       No
Com_set_option                                                                                                                                                                                                 Yes                                                        Both                                                       No
Com_show_binlog_events                                                                                                                                                                                         Yes                                                        Both                                                       No
Com_show_binlogs                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_show_charsets                                                                                                                                                                                              Yes                                                        Both                                                       No
Com_show_collations                                                                                                                                                                                            Yes                                                        Both                                                       No
Com_show_column_types                                                                                                                                                                                          Yes                                                        Both                                                       No
Com_show_create_db                                                                                                                                                                                             Yes                                                        Both                                                       No
Com_show_create_event                                                                                                                                                                                          Yes                                                        Both                                                       No
Com_show_create_table                                                                                                                                                                                          Yes                                                        Both                                                       No
Com_show_databases                                                                                                                                                                                             Yes                                                        Both                                                       No
Com_show_engine_logs                                                                                                                                                                                           Yes                                                        Both                                                       No
Com_show_engine_mutex                                                                                                                                                                                          Yes                                                        Both                                                       No
Com_show_engine_status                                                                                                                                                                                         Yes                                                        Both                                                       No
Com_show_errors                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_show_events                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_show_fields                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_show_grants                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_show_innodb_status                                                                                                                                                                                         Yes                                                        Both                                                       No
Com_show_keys                                                                                                                                                                                                  Yes                                                        Both                                                       No
Com_show_logs                                                                                                                                                                                                  Yes                                                        Both                                                       No
Com_show_master_status                                                                                                                                                                                         Yes                                                        Both                                                       No
Com_show_ndb_status                                                                                                                                                                                            Yes                                                        Both                                                       No
Com_show_new_master                                                                                                                                                                                            Yes                                                        Both                                                       No
Com_show_open_tables                                                                                                                                                                                           Yes                                                        Both                                                       No
Com_show_plugins                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_show_privileges                                                                                                                                                                                            Yes                                                        Both                                                       No
Com_show_processlist                                                                                                                                                                                           Yes                                                        Both                                                       No
Com_show_slave_hosts                                                                                                                                                                                           Yes                                                        Both                                                       No
Com_show_slave_status                                                                                                                                                                                          Yes                                                        Both                                                       No
Com_show_status                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_show_storage_engines                                                                                                                                                                                       Yes                                                        Both                                                       No
Com_show_tables                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_show_triggers                                                                                                                                                                                              Yes                                                        Both                                                       No
Com_show_variables                                                                                                                                                                                             Yes                                                        Both                                                       No
Com_show_warnings                                                                                                                                                                                              Yes                                                        Both                                                       No
Com_slave_start                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_slave_stop                                                                                                                                                                                                 Yes                                                        Both                                                       No
Com_stmt_close                                                                                                                                                                                                 Yes                                                        Both                                                       No
Com_stmt_execute                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_stmt_fetch                                                                                                                                                                                                 Yes                                                        Both                                                       No
Com_stmt_prepare                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_stmt_reprepare                                                                                                                                                                                             Yes                                                        Both                                                       No
Com_stmt_reset                                                                                                                                                                                                 Yes                                                        Both                                                       No
Com_stmt_send_long_data                                                                                                                                                                                        Yes                                                        Both                                                       No
Com_truncate                                                                                                                                                                                                   Yes                                                        Both                                                       No
Com_unlock_tables                                                                                                                                                                                              Yes                                                        Both                                                       No
Com_update                                                                                                                                                                                                     Yes                                                        Both                                                       No
Com_update_multi                                                                                                                                                                                               Yes                                                        Both                                                       No
Com_xa_commit                                                                                                                                                                                                  Yes                                                        Both                                                       No
Com_xa_end                                                                                                                                                                                                     Yes                                                        Both                                                       No
Com_xa_prepare                                                                                                                                                                                                 Yes                                                        Both                                                       No
Com_xa_recover                                                                                                                                                                                                 Yes                                                        Both                                                       No
Com_xa_rollback                                                                                                                                                                                                Yes                                                        Both                                                       No
Com_xa_start                                                                                                                                                                                                   Yes                                                        Both                                                       No
concurrent_insert             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
Connections                                                                                                                                                                                                    Yes                                                        Both                                                       No
connect_timeout               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
console                       Yes                                                        Yes                                                                                                                                                                                                                                         
core-file                     Yes                                                        Yes                                                                                                                                                                                                                                         
Created_tmp_disk_tables                                                                                                                                                                                        Yes                                                        Both                                                       No
Created_tmp_files                                                                                                                                                                                              Yes                                                        Both                                                       No
Created_tmp_tables                                                                                                                                                                                             Yes                                                        Both                                                       No
datadir                       Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
date_format                                                                                                                                         Yes                                                                                                                   Both                                                       Yes
datetime_format               Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
debug                         Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
defaults-extra-file           Yes                                                                                                                                                                                                                                                                                                    
defaults-file                 Yes                                                                                                                                                                                                                                                                                                    
defaults-group-suffix         Yes                                                                                                                                                                                                                                                                                                    
default-storage-engine        Yes                                                        Yes                                                                                                                                                                                                                                         
default-table-type            Yes                                                        Yes                                                                                                                                                                                                                                         
default-time-zone             Yes                                                        Yes                                                                                                                                                                                                                                         
default_week_format           Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
Delayed_errors                                                                                                                                                                                                 Yes                                                        Both                                                       No
delayed_insert_limit          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
Delayed_insert_threads                                                                                                                                                                                         Yes                                                        Both                                                       No
delayed_insert_timeout        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
delayed_queue_size            Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
Delayed_writes                                                                                                                                                                                                 Yes                                                        Both                                                       No
delay-key-write               Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: delay_key_write                                                                                                                       Yes                                                                                                                   Global                                                     Yes
des-key-file                  Yes                                                        Yes                                                                                                                                                                                                                                         
disconnect-slave-event-count  Yes                                                        Yes                                                                                                                                                                                                                                         
div_precision_increment       Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
enable-locking                Yes                                                                                                                                                                                                                                                                                                    
enable-named-pipe             Yes                                                        Yes                                                                                                                                                                                                                                         
enable-pstack                 Yes                                                        Yes                                                                                                                                                                                                                                         
engine-condition-pushdown     Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Both                                                       Yes
engine_condition_pushdown                                                                                                                                                                                                                                                                                                            
error_count                                                                                                                                         Yes                                                                                                                   Session                                                    No
event-scheduler               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
exit-info                     Yes                                                        Yes                                                                                                                                                                                                                                         
expire_logs_days              Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
external-locking              Yes                                                        Yes                                                                                                                                                                                                                                         
- _Variable_:                                                                                                                                                                                                                                                                                                                        
external_locking                                                                                                                                                                                                                                                                                                                     
flush                         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
Flush_commands                                                                                                                                                                                                 Yes                                                        Both                                                       No
flush_time                    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
foreign_key_checks                                                                                                                                  Yes                                                                                                                   Session                                                    Yes
ft_boolean_syntax             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
ft_max_word_len               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
ft_min_word_len               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
ft_query_expansion_limit      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
ft_stopword_file              Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
gdb                           Yes                                                        Yes                                                                                                                                                                                                                                         
general-log                   Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: general_log                                                                                                                           Yes                                                                                                                   Global                                                     Yes
general_log_file                                                                                                                                    Yes                                                                                                                   Global                                                     Yes
group_concat_max_len          Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
Handler_commit                                                                                                                                                                                                 Yes                                                        Both                                                       No
Handler_delete                                                                                                                                                                                                 Yes                                                        Both                                                       No
Handler_discover                                                                                                                                                                                               Yes                                                        Both                                                       No
Handler_prepare                                                                                                                                                                                                Yes                                                        Both                                                       No
Handler_read_first                                                                                                                                                                                             Yes                                                        Both                                                       No
Handler_read_key                                                                                                                                                                                               Yes                                                        Both                                                       No
Handler_read_next                                                                                                                                                                                              Yes                                                        Both                                                       No
Handler_read_prev                                                                                                                                                                                              Yes                                                        Both                                                       No
Handler_read_rnd                                                                                                                                                                                               Yes                                                        Both                                                       No
Handler_read_rnd_next                                                                                                                                                                                          Yes                                                        Both                                                       No
Handler_rollback                                                                                                                                                                                               Yes                                                        Both                                                       No
Handler_savepoint                                                                                                                                                                                              Yes                                                        Both                                                       No
Handler_savepoint_rollback                                                                                                                                                                                     Yes                                                        Both                                                       No
Handler_update                                                                                                                                                                                                 Yes                                                        Both                                                       No
Handler_write                                                                                                                                                                                                  Yes                                                        Both                                                       No
have_archive                                                                                                                                        Yes                                                                                                                   Global                                                     No
have_blackhole_engine                                                                                                                               Yes                                                                                                                   Global                                                     No
have_compress                                                                                                                                       Yes                                                                                                                   Global                                                     No
have_crypt                                                                                                                                          Yes                                                                                                                   Global                                                     No
have_csv                                                                                                                                            Yes                                                                                                                   Global                                                     No
have_dynamic_loading                                                                                                                                Yes                                                                                                                   Global                                                     No
have_example_engine                                                                                                                                 Yes                                                                                                                   Global                                                     No
have_federated_engine                                                                                                                               Yes                                                                                                                   Global                                                     No
have_geometry                                                                                                                                       Yes                                                                                                                   Global                                                     No
have_innodb                                                                                                                                         Yes                                                                                                                   Global                                                     No
have_isam                                                                                                                                           Yes                                                                                                                   Global                                                     No
have_merge_engine                                                                                                                                   Yes                                                                                                                   Global                                                     No
have_ndbcluster                                                                                                                                     Yes                                                                                                                   Global                                                     No
have_openssl                                                                                                                                        Yes                                                                                                                   Global                                                     No
have_partitioning                                                                                                                                   Yes                                                                                                                   Global                                                     No
have_query_cache                                                                                                                                    Yes                                                                                                                   Global                                                     No
have_raid                                                                                                                                           Yes                                                                                                                   Global                                                     No
have_row_based_replication                                                                                                                          Yes                                                                                                                   Global                                                     No
have_rtree_keys                                                                                                                                     Yes                                                                                                                   Global                                                     No
have_ssl                                                                                                                                            Yes                                                                                                                   Global                                                     No
have_symlink                                                                                                                                        Yes                                                                                                                   Global                                                     No
help                          Yes                                                                                                                                                                                                                                                                                                    
hostname                                                                                                                                            Yes                                                                                                                   Global                                                     No
identity                                                                                                                                            Yes                                                                                                                   Session                                                    Yes
init_connect                  Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
init-file                     Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: init_file                                                                                                                             Yes                                                                                                                   Global                                                     No
init_slave                    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb                        Yes                                                        Yes                                                                                                                                                                                                                                         
innodb_adaptive_hash_index    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_additional_mem_pool_sizeYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_autoextend_increment   Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_autoinc_lock_mode      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_buffer_pool_awe_mem_mb Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_buffer_pool_pages_data                                                                                                                                                                                  Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_dirty                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_flushed                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_free                                                                                                                                                                                  Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_latched                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_misc                                                                                                                                                                                  Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_total                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_read_ahead_rnd                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_read_ahead_seq                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_read_requests                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_reads                                                                                                                                                                                       Yes                                                        Global                                                     No
innodb_buffer_pool_size       Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_buffer_pool_wait_free                                                                                                                                                                                   Yes                                                        Global                                                     No
Innodb_buffer_pool_write_requests                                                                                                                                                                                 Yes                                                        Global                                                     No
innodb_checksums              Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_commit_concurrency     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_concurrency_tickets    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_data_file_path         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_data_fsyncs                                                                                                                                                                                             Yes                                                        Global                                                     No
innodb_data_home_dir          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_data_pending_fsyncs                                                                                                                                                                                     Yes                                                        Global                                                     No
Innodb_data_pending_reads                                                                                                                                                                                      Yes                                                        Global                                                     No
Innodb_data_pending_writes                                                                                                                                                                                     Yes                                                        Global                                                     No
Innodb_data_read                                                                                                                                                                                               Yes                                                        Global                                                     No
Innodb_data_reads                                                                                                                                                                                              Yes                                                        Global                                                     No
Innodb_data_writes                                                                                                                                                                                             Yes                                                        Global                                                     No
Innodb_data_written                                                                                                                                                                                            Yes                                                        Global                                                     No
Innodb_dblwr_pages_written                                                                                                                                                                                     Yes                                                        Global                                                     No
Innodb_dblwr_writes                                                                                                                                                                                            Yes                                                        Global                                                     No
innodb_doublewrite            Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_fast_shutdown          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_file_io_threads        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_file_per_table         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_flush_log_at_trx_commitYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_flush_method           Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_force_recovery         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_locks_unsafe_for_binlogYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_lock_wait_timeout      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_log_arch_dir           Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_log_archive            Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_log_buffer_size        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_log_files_in_group     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_log_file_size          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_log_group_home_dir     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_log_waits                                                                                                                                                                                               Yes                                                        Global                                                     No
Innodb_log_write_requests                                                                                                                                                                                      Yes                                                        Global                                                     No
Innodb_log_writes                                                                                                                                                                                              Yes                                                        Global                                                     No
innodb_max_dirty_pages_pct    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_max_purge_lag          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_mirrored_log_groups    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_open_files             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_os_log_fsyncs                                                                                                                                                                                           Yes                                                        Global                                                     No
Innodb_os_log_pending_fsyncs                                                                                                                                                                                   Yes                                                        Global                                                     No
Innodb_os_log_pending_writes                                                                                                                                                                                   Yes                                                        Global                                                     No
Innodb_os_log_written                                                                                                                                                                                          Yes                                                        Global                                                     No
Innodb_pages_created                                                                                                                                                                                           Yes                                                        Global                                                     No
Innodb_page_size                                                                                                                                                                                               Yes                                                        Global                                                     No
Innodb_pages_read                                                                                                                                                                                              Yes                                                        Global                                                     No
Innodb_pages_written                                                                                                                                                                                           Yes                                                        Global                                                     No
innodb_rollback_on_timeout    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_row_lock_current_waits                                                                                                                                                                                  Yes                                                        Global                                                     No
Innodb_row_lock_time                                                                                                                                                                                           Yes                                                        Global                                                     No
Innodb_row_lock_time_avg                                                                                                                                                                                       Yes                                                        Global                                                     No
Innodb_row_lock_time_max                                                                                                                                                                                       Yes                                                        Global                                                     No
Innodb_row_lock_waits                                                                                                                                                                                          Yes                                                        Global                                                     No
Innodb_rows_deleted                                                                                                                                                                                            Yes                                                        Global                                                     No
Innodb_rows_inserted                                                                                                                                                                                           Yes                                                        Global                                                     No
Innodb_rows_read                                                                                                                                                                                               Yes                                                        Global                                                     No
Innodb_rows_updated                                                                                                                                                                                            Yes                                                        Global                                                     No
innodb_stats_on_metadata      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_status_file            Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_support_xa             Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
innodb_sync_spin_loops        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_table_locks            Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
innodb_thread_concurrency     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_thread_sleep_delay     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
insert_id                                                                                                                                           Yes                                                                                                                   Session                                                    Yes
interactive_timeout           Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
join_buffer_size              Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
keep_files_on_create          Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
Key_blocks_not_flushed                                                                                                                                                                                         Yes                                                        Both                                                       No
Key_blocks_unused                                                                                                                                                                                              Yes                                                        Both                                                       No
Key_blocks_used                                                                                                                                                                                                Yes                                                        Both                                                       No
key_buffer_size               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
key_cache_age_threshold       Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
key_cache_block_size          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
key_cache_division_limit      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
Key_read_requests                                                                                                                                                                                              Yes                                                        Both                                                       No
Key_reads                                                                                                                                                                                                      Yes                                                        Both                                                       No
Key_write_requests                                                                                                                                                                                             Yes                                                        Both                                                       No
Key_writes                                                                                                                                                                                                     Yes                                                        Both                                                       No
language                      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
large-pages                   Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: large_pages                                                                                                                           Yes                                                                                                                   Global                                                     No
large_page_size                                                                                                                                     Yes                                                                                                                   Global                                                     No
last_insert_id                                                                                                                                      Yes                                                                                                                   Session                                                    Yes
Last_query_cost                                                                                                                                                                                                Yes                                                        Both                                                       No
lc_time_names                                                                                                                                       Yes                                                                                                                   Both                                                       Yes
license                                                                                                                                             Yes                                                                                                                   Global                                                     No
local_infile                                                                                                                                        Yes                                                                                                                   Global                                                     Yes
local-infile                  Yes                                                        Yes                                                                                                                                                                                                                                         
locked_in_memory                                                                                                                                    Yes                                                                                                                   Global                                                     No
log                           Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
log_bin                                                                                                                                             Yes                                                                                                                   Global                                                     No
log-bin                       Yes                                                        Yes                                                                                                                                                                                                                                         
log-bin-index                 Yes                                                        Yes                                                                                                                                                                                                                                         
log-bin-trust-function-creatorsYes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
log_bin_trust_function_creators                                                                                                                                                                                                                                                                                                       
log-bin-trust-routine-creatorsYes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
log_bin_trust_routine_creators                                                                                                                                                                                                                                                                                                       
log-error                     Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: log_error                                                                                                                             Yes                                                                                                                   Global                                                     No
log-isam                      Yes                                                        Yes                                                                                                                                                                                                                                         
log-output                    Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: log_output                                                                                                                            Yes                                                                                                                   Global                                                     Yes
log-queries-not-using-indexes Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
log_queries_not_using_indexes                                                                                                                                                                                                                                                                                                        
log-short-format              Yes                                                        Yes                                                                                                                                                                                                                                         
log-slave-updates             Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
log_slave_updates                                                                                                                                                                                                                                                                                                                    
log-slow-admin-statements     Yes                                                        Yes                                                                                                                                                                                                                                         
log-slow-queries              Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
log_slow_queries                                                                                                                                                                                                                                                                                                                     
log-slow-slave-statements     Yes                                                        Yes                                                                                                                                                                                                                                         
log-tc                        Yes                                                        Yes                                                                                                                                                                                                                                         
log-tc-size                   Yes                                                        Yes                                                                                                                                                                                                                                         
log-warnings                  Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_: log_warnings                                                                                                                          Yes                                                                                                                   Both                                                       Yes
long_query_time               Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
lower_case_file_system        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
lower_case_table_names        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
low-priority-updates          Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_:                                                                                                                                       Yes                                                                                                                   Both                                                       Yes
low_priority_updates                                                                                                                                                                                                                                                                                                                 
*Note master-bind:            Yes                                                        Yes                                                        Yes                                                                                                                                                                              No
replication-options.                                                                                                                                                                                                                                                                                                                 
*Note master-connect-retry:   Yes                                                        Yes                                                                                                                                                                                                                                         
replication-options.                                                                                                                                                                                                                                                                                                                 
*Note master-host:            Yes                                                        Yes                                                                                                                                                                                                                                         
replication-options.                                                                                                                                                                                                                                                                                                                 
*Note master-info-file:       Yes                                                        Yes                                                                                                                                                                                                                                         
replication-options.                                                                                                                                                                                                                                                                                                                 
*Note master-password:        Yes                                                        Yes                                                                                                                                                                                                                                         
replication-options.                                                                                                                                                                                                                                                                                                                 
*Note master-port:            Yes                                                        Yes                                                                                                                                                                                                                                         
replication-options.                                                                                                                                                                                                                                                                                                                 
*Note master-retry-count:     Yes                                                        Yes                                                                                                                                                                                                                                         
replication-options.                                                                                                                                                                                                                                                                                                                 
master-ssl                    Yes                                                        Yes                                                                                                                                                                                                                                         
master-ssl-ca                 Yes                                                        Yes                                                                                                                                                                                                                                         
master-ssl-capath             Yes                                                        Yes                                                                                                                                                                                                                                         
master-ssl-cert               Yes                                                        Yes                                                                                                                                                                                                                                         
master-ssl-cipher             Yes                                                        Yes                                                                                                                                                                                                                                         
master-ssl-key                Yes                                                        Yes                                                                                                                                                                                                                                         
*Note master-user:            Yes                                                        Yes                                                                                                                                                                                                                                         
replication-options.                                                                                                                                                                                                                                                                                                                 
max_allowed_packet            Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
max_binlog_cache_size         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
max-binlog-dump-events        Yes                                                        Yes                                                                                                                                                                                                                                         
max_binlog_size               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
max_connect_errors            Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
max_connections               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
max_delayed_threads           Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
max_error_count               Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
max_heap_table_size           Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
max_insert_delayed_threads                                                                                                                          Yes                                                                                                                   Both                                                       Yes
max_join_size                 Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
max_length_for_sort_data      Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
max_prepared_stmt_count       Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
max_relay_log_size            Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
max_seeks_for_key             Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
max_sort_length               Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
max_sp_recursion_depth        Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
max_tmp_tables                Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
Max_used_connections                                                                                                                                                                                           Yes                                                        Both                                                       No
max_user_connections          Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
max_write_lock_count          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
memlock                       Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
merge                         Yes                                                        Yes                                                                                                                                                                                                                                         
min-examined-row-limit        Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
multi_range_count             Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
myisam_block_size             Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
myisam_data_pointer_size      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
myisam_max_sort_file_size     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
myisam-recover                Yes                                                        Yes                                                                                                                                                                                                                                         
myisam_recover_options                                                                                                                              Yes                                                                                                                   Global                                                     No
myisam_repair_threads         Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
myisam_sort_buffer_size       Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
myisam_stats_method           Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
myisam_use_mmap               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
named_pipe                                                                                                                                          Yes                                                                                                                   Global                                                     No
ndb_autoincrement_prefetch_sz Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
ndb-batch-size                Yes                                                        Yes                                                                                                                                                                                                                                         
ndb_cache_check_time          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
ndbcluster                    Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
ndb-cluster-connection-pool   Yes                                                        Yes                                                                                                                   Yes                                                        Global                                                     No
Ndb_cluster_node_id                                                                                                                                                                                            Yes                                                        Both                                                       No
Ndb_config_from_host                                                                                                                                                                                           Yes                                                        Both                                                       No
Ndb_config_from_port                                                                                                                                                                                           Yes                                                        Both                                                       No
Ndb_conflict_fn_max                                                                                                                                                                                            Yes                                                        Both                                                       No
Ndb_conflict_fn_old                                                                                                                                                                                            Yes                                                        Both                                                       No
ndb-connectstring             Yes                                                        Yes                                                                                                                                                                                                                                         
ndb_execute_count                                                                                                                                                                                              Yes                                                        Global                                                     No
ndb_extra_logging             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
ndb_force_send                Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
ndb_index_stat_cache_entries  Yes                                                        Yes                                                                                                                                                                                                                                         
ndb_index_stat_enable         Yes                                                        Yes                                                                                                                                                                                                                                         
ndb_index_stat_update_freq    Yes                                                        Yes                                                                                                                                                                                                                                         
*Note ndb_log_orig:                                                                                                                                 Yes                                                                                                                   Global                                                     No
mysql-cluster-replication-schema.                                                                                                                                                                                                                                                                                                       
ndb_log_update_as_write       Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
ndb_log_updated_only          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
Ndb_number_of_data_nodes                                                                                                                                                                                       Yes                                                        Both                                                       No
ndb_optimization_delay                                                                                                                              Yes                                                                                                                   Global                                                     Yes
ndb_optimized_node_selection  Yes                                                        Yes                                                                                                                                                                                                                                         
ndb_report_thresh_binlog_epoch_slipYes                                                        Yes                                                                                                                                                                                                                                         
ndb_report_thresh_binlog_mem_usageYes                                                        Yes                                                                                                                                                                                                                                         
ndb_table_no_logging                                                                                                                                Yes                                                                                                                   Session                                                    Yes
ndb_table_temporary                                                                                                                                 Yes                                                                                                                   Session                                                    Yes
ndb_use_copying_alter_table                                                                                                                         Yes                                                                                                                   Both                                                       No
ndb_use_exact_count                                                                                                                                 Yes                                                                                                                   Both                                                       Yes
ndb_use_transactions          Yes                                                        Yes                                                                                                                                                                                                                                         
ndb_wait_connected            Yes                                                        Yes                                                        Yes                                                                                                                                                                              No
net_buffer_length             Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
net_read_timeout              Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
net_retry_count               Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
net_write_timeout             Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
new                           Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
no-defaults                   Yes                                                                                                                                                                                                                                                                                                    
Not_flushed_delayed_rows                                                                                                                                                                                       Yes                                                        Both                                                       No
old                           Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
old-alter-table               Yes                                                        Yes                                                                                                                                                                                                                                         
old-passwords                 Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_: old_passwords                                                                                                                         Yes                                                                                                                   Both                                                       Yes
old-style-user-limits         Yes                                                        Yes                                                                                                                                                                                                                                         
one-thread                    Yes                                                        Yes                                                                                                                                                                                                                                         
Opened_files                                                                                                                                                                                                   Yes                                                        Global                                                     No
Opened_tables                                                                                                                                                                                                  Yes                                                        Both                                                       No
Open_files                                                                                                                                                                                                     Yes                                                        Both                                                       No
open-files-limit              Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
open_files_limit                                                                                                                                                                                                                                                                                                                     
Open_streams                                                                                                                                                                                                   Yes                                                        Both                                                       No
Open_table_definitions                                                                                                                                                                                         Yes                                                        Both                                                       No
Open_tables                                                                                                                                                                                                    Yes                                                        Both                                                       No
optimizer_prune_level         Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
optimizer_search_depth        Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
pid-file                      Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: pid_file                                                                                                                              Yes                                                                                                                   Global                                                     No
plugin_dir                    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin-innodb                 Yes                                                        Yes                                                                                                                                                                                                                                         
plugin_innodb_additional_mem_pool_sizeYes                                                        Yes                                                        Yes                                                                                                                   Both                                                       No
plugin_innodb_autoextend_incrementYes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
plugin_innodb_buffer_pool_awe_mem_mbYes                                                        Yes                                                                                                                                                                              Both                                                       No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Both                                                       No
innodb_buffer_pool_awe_mem_mb                                                                                                                                                                                                                                                                                                        
plugin_innodb_buffer_pool_sizeYes                                                        Yes                                                        Yes                                                                                                                   Both                                                       No
plugin_innodb_checksums       Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
plugin_innodb_commit_concurrencyYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
plugin_innodb_concurrency_ticketsYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
plugin_innodb_data_file_path  Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_data_home_dir   Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin-innodb-doublewrite     Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
plugin_innodb_doublewrite                                                                                                                                                                                                                                                                                                            
plugin_innodb_fast_shutdown   Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_file_io_threads Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_file_per_table  Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_flush_log_at_trx_commitYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
plugin_innodb_flush_method    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_force_recovery  Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_locks_unsafe_for_binlogYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_lock_wait_timeoutYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_log_archive     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_log_buffer_size Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_log_files_in_groupYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_log_file_size   Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_log_group_home_dirYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_max_dirty_pages_pctYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
plugin_innodb_max_purge_lag   Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
plugin_innodb_mirrored_log_groupsYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_open_files      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_rollback_on_timeoutYes                                                        Yes                                                        Yes                                                                                                                                                                              No
plugin_innodb_stats_on_metadataYes                                                        Yes                                                        Yes                                                                                                                                                                              No
plugin_innodb_status_file     Yes                                                        Yes                                                        Yes                                                                                                                                                                              No
plugin_innodb_support_xa      Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
plugin_innodb_sync_spin_loops Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
plugin_innodb_table_locks     Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
plugin_innodb_thread_concurrencyYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
plugin_innodb_thread_sleep_delayYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
port                          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
port-open-timeout             Yes                                                        Yes                                                                                                                                                                                                                                         
preload_buffer_size           Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
prepared_stmt_count                                                                                                                                 Yes                                                        Yes                                                        Global                                                     No
print-defaults                Yes                                                                                                                                                                                                                                                                                                    
protocol_version                                                                                                                                    Yes                                                                                                                   Global                                                     No
Qcache_free_blocks                                                                                                                                                                                             Yes                                                        Both                                                       No
Qcache_free_memory                                                                                                                                                                                             Yes                                                        Both                                                       No
Qcache_hits                                                                                                                                                                                                    Yes                                                        Both                                                       No
Qcache_inserts                                                                                                                                                                                                 Yes                                                        Both                                                       No
Qcache_lowmem_prunes                                                                                                                                                                                           Yes                                                        Both                                                       No
Qcache_not_cached                                                                                                                                                                                              Yes                                                        Both                                                       No
Qcache_queries_in_cache                                                                                                                                                                                        Yes                                                        Both                                                       No
Qcache_total_blocks                                                                                                                                                                                            Yes                                                        Both                                                       No
query_alloc_block_size        Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
query_cache_limit             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
query_cache_min_res_unit      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
query_cache_size              Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
query_cache_type              Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
query_cache_wlock_invalidate  Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
query_prealloc_size           Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
Questions                                                                                                                                                                                                      Yes                                                        Both                                                       No
range_alloc_block_size        Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
read_buffer_size              Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
read_only                     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
read_rnd_buffer_size          Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
*Note relay-log:              Yes                                                        Yes                                                                                                                                                                                                                                         
replication-options.                                                                                                                                                                                                                                                                                                                 
relay-log-index               Yes                                                        Yes                                                                                                                                                                                                                                         
relay-log-info-file           Yes                                                        Yes                                                                                                                                                                                                                                         
relay_log_purge               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
relay_log_space_limit         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
*Note replicate-do-db:        Yes                                                        Yes                                                                                                                                                                                                                                         
replication-options.                                                                                                                                                                                                                                                                                                                 
*Note replicate-do-table:     Yes                                                        Yes                                                                                                                                                                                                                                         
replication-options.                                                                                                                                                                                                                                                                                                                 
*Note replicate-ignore-db:    Yes                                                        Yes                                                                                                                                                                                                                                         
replication-options.                                                                                                                                                                                                                                                                                                                 
*Note                         Yes                                                        Yes                                                                                                                                                                                                                                         
replicate-ignore-table:                                                                                                                                                                                                                                                                                                              
replication-options.                                                                                                                                                                                                                                                                                                                 
*Note replicate-rewrite-db:   Yes                                                        Yes                                                                                                                                                                                                                                         
replication-options.                                                                                                                                                                                                                                                                                                                 
*Note                         Yes                                                        Yes                                                                                                                                                                                                                                         
replicate-same-server-id:                                                                                                                                                                                                                                                                                                            
replication-options.                                                                                                                                                                                                                                                                                                                 
*Note                         Yes                                                        Yes                                                                                                                                                                                                                                         
replicate-wild-do-table:                                                                                                                                                                                                                                                                                                             
replication-options.                                                                                                                                                                                                                                                                                                                 
*Note                         Yes                                                        Yes                                                                                                                                                                                                                                         
replicate-wild-ignore-table:                                                                                                                                                                                                                                                                                                         
replication-options.                                                                                                                                                                                                                                                                                                                 
report-host                   Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: report_host                                                                                                                           Yes                                                                                                                   Global                                                     No
report-password               Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: report_password                                                                                                                       Yes                                                                                                                   Global                                                     No
report-port                   Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: report_port                                                                                                                           Yes                                                                                                                   Global                                                     No
report-user                   Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: report_user                                                                                                                           Yes                                                                                                                   Global                                                     No
*Note rpl_recovery_rank:                                                                                                                            Yes                                                                                                                   Global                                                     Yes
replication-options.                                                                                                                                                                                                                                                                                                                 
Rpl_status                                                                                                                                                                                                     Yes                                                        Both                                                       No
safemalloc-mem-limit          Yes                                                        Yes                                                                                                                                                                                                                                         
safe-mode                     Yes                                                        Yes                                                                                                                                                                                                                                         
safe-user-create              Yes                                                        Yes                                                                                                                                                                                                                                         
secure-auth                   Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: secure_auth                                                                                                                           Yes                                                                                                                   Global                                                     Yes
secure-file-priv              Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
secure_file_priv                                                                                                                                                                                                                                                                                                                     
Select_full_join                                                                                                                                                                                               Yes                                                        Both                                                       No
Select_full_range_join                                                                                                                                                                                         Yes                                                        Both                                                       No
Select_range                                                                                                                                                                                                   Yes                                                        Both                                                       No
Select_range_check                                                                                                                                                                                             Yes                                                        Both                                                       No
Select_scan                                                                                                                                                                                                    Yes                                                        Both                                                       No
server-id                     Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: server_id                                                                                                                             Yes                                                                                                                   Global                                                     Yes
shared_memory                                                                                                                                       Yes                                                                                                                   Global                                                     No
shared_memory_base_name                                                                                                                             Yes                                                                                                                   Global                                                     No
show-slave-auth-info          Yes                                                        Yes                                                                                                                                                                                                                                         
skip-character-set-client-handshakeYes                                                        Yes                                                                                                                                                                                                                                         
skip-concurrent-insert        Yes                                                        Yes                                                                                                                                                                                                                                         
- _Variable_:                                                                                                                                                                                                                                                                                                                        
concurrent_insert                                                                                                                                                                                                                                                                                                                    
skip-external-locking         Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
skip_external_locking                                                                                                                                                                                                                                                                                                                
skip-grant-tables             Yes                                                        Yes                                                                                                                                                                                                                                         
skip-host-cache               Yes                                                        Yes                                                                                                                                                                                                                                         
skip-innodb                   Yes                                                        Yes                                                                                                                                                                                                                                         
skip-innodb-checksums         Yes                                                        Yes                                                                                                                                                                                                                                         
skip-locking                  Yes                                                        Yes                                                                                                                                                                                                                                         
skip-log-warnings             Yes                                                                                                                                                                                                                                                                                                    
skip-merge                    Yes                                                        Yes                                                                                                                                                                                                                                         
- _Variable_:                                                                                                                                                                                                                                                                                                                        
skip-name-resolve             Yes                                                        Yes                                                                                                                                                                                                                                         
skip-ndbcluster               Yes                                                        Yes                                                                                                                                                                                                                                         
skip-networking               Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: skip_networking                                                                                                                       Yes                                                                                                                   Global                                                     No
skip-new                      Yes                                                        Yes                                                                                                                                                                                                                                         
skip-plugin-innodb            Yes                                                        Yes                                                                                                                                                                                                                                         
skip-plugin-innodb-checksums  Yes                                                        Yes                                                                                                                                                                                                                                         
skip-safemalloc               Yes                                                        Yes                                                                                                                                                                                                                                         
skip-show-database            Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
skip_show_database                                                                                                                                                                                                                                                                                                                   
*Note skip-slave-start:       Yes                                                        Yes                                                                                                                                                                                                                                         
replication-options.                                                                                                                                                                                                                                                                                                                 
skip-ssl                      Yes                                                        Yes                                                                                                                                                                                                                                         
skip-stack-trace              Yes                                                        Yes                                                                                                                                                                                                                                         
skip-symbolic-links           Yes                                                                                                                                                                                                                                                                                                    
skip-symlink                  Yes                                                        Yes                                                                                                                                                                                                                                         
skip-thread-priority          Yes                                                        Yes                                                                                                                                                                                                                                         
*Note slave-allow-batching:   Yes                                                                                                                                                                                                                                         Global                                                     Yes
mysql-cluster-replication-starting.                                                                                                                                                                                                                                                                                                       
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
slave_allow_batching                                                                                                                                                                                                                                                                                                                 
slave_compressed_protocol     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
slave_exec_mode                                                                                                                                     Yes                                                                                                                   Global                                                     Yes
Slave_heartbeat_period                                                                                                                                                                                         Yes                                                        Global                                                     No
*Note slave-load-tmpdir:      Yes                                                        Yes                                                                                                                                                                              Global                                                     No
replication-options.                                                                                                                                                                                                                                                                                                                 
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
slave_load_tmpdir                                                                                                                                                                                                                                                                                                                    
*Note slave-net-timeout:      Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
replication-options.                                                                                                                                                                                                                                                                                                                 
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
slave_net_timeout                                                                                                                                                                                                                                                                                                                    
Slave_open_temp_tables                                                                                                                                                                                         Yes                                                        Both                                                       No
Slave_received_heartbeats                                                                                                                                                                                      Yes                                                        Global                                                     No
Slave_retried_transactions                                                                                                                                                                                     Yes                                                        Both                                                       No
Slave_running                                                                                                                                                                                                  Yes                                                        Both                                                       No
*Note slave-skip-errors:      Yes                                                        Yes                                                                                                                                                                              Global                                                     No
replication-options.                                                                                                                                                                                                                                                                                                                 
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
slave_skip_errors                                                                                                                                                                                                                                                                                                                    
slave_transaction_retries     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
Slow_launch_threads                                                                                                                                                                                            Yes                                                        Both                                                       No
slow_launch_time              Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
Slow_queries                                                                                                                                                                                                   Yes                                                        Both                                                       No
slow-query-log                Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: slow_query_log                                                                                                                        Yes                                                                                                                   Global                                                     Yes
slow_query_log_file                                                                                                                                 Yes                                                                                                                   Global                                                     Yes
socket                        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
sort_buffer_size              Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
Sort_merge_passes                                                                                                                                                                                              Yes                                                        Both                                                       No
Sort_range                                                                                                                                                                                                     Yes                                                        Both                                                       No
Sort_rows                                                                                                                                                                                                      Yes                                                        Both                                                       No
Sort_scan                                                                                                                                                                                                      Yes                                                        Both                                                       No
sporadic-binlog-dump-fail     Yes                                                        Yes                                                                                                                                                                                                                                         
sql_auto_is_null                                                                                                                                    Yes                                                                                                                   Session                                                    Yes
sql_big_selects                                                                                                                                     Yes                                                                                                                   Session                                                    Yes
sql_big_tables                                                                                                                                      Yes                                                                                                                   Session                                                    Yes
sql_buffer_result                                                                                                                                   Yes                                                                                                                   Session                                                    Yes
sql_log_bin                                                                                                                                         Yes                                                                                                                   Session                                                    Yes
sql_log_off                                                                                                                                         Yes                                                                                                                   Session                                                    Yes
sql_log_update                                                                                                                                      Yes                                                                                                                   Session                                                    Yes
sql_low_priority_updates                                                                                                                            Yes                                                                                                                   Both                                                       Yes
sql_max_join_size                                                                                                                                   Yes                                                                                                                   Both                                                       Yes
sql-mode                      Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_: sql_mode                                                                                                                              Yes                                                                                                                   Both                                                       Yes
sql_notes                                                                                                                                           Yes                                                                                                                   Session                                                    Yes
sql_quote_show_create                                                                                                                               Yes                                                                                                                   Session                                                    Yes
sql_safe_updates                                                                                                                                    Yes                                                                                                                   Session                                                    Yes
sql_select_limit                                                                                                                                    Yes                                                                                                                   Both                                                       Yes
sql_slave_skip_counter                                                                                                                              Yes                                                                                                                   Global                                                     Yes
sql_warnings                                                                                                                                        Yes                                                                                                                   Session                                                    Yes
ssl                           Yes                                                        Yes                                                                                                                                                                                                                                         
ssl-ca                        Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: ssl_ca                                                                                                                                Yes                                                                                                                   Global                                                     No
ssl-capath                    Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: ssl_capath                                                                                                                            Yes                                                                                                                   Global                                                     No
ssl-cert                      Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: ssl_cert                                                                                                                              Yes                                                                                                                   Global                                                     No
ssl-cipher                    Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: ssl_cipher                                                                                                                            Yes                                                                                                                   Global                                                     No
ssl-key                       Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: ssl_key                                                                                                                               Yes                                                                                                                   Global                                                     No
ssl-verify-server-cert        Yes                                                        Yes                                                                                                                                                                                                                                         
standalone                    Yes                                                        Yes                                                                                                                                                                                                                                         
storage_engine                                                                                                                                      Yes                                                                                                                   Both                                                       Yes
symbolic-links                Yes                                                        Yes                                                                                                                                                                                                                                         
sync-binlog                   Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: sync_binlog                                                                                                                           Yes                                                                                                                   Global                                                     Yes
sync-frm                      Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: sync_frm                                                                                                                              Yes                                                                                                                   Global                                                     Yes
sysdate-is-now                Yes                                                        Yes                                                                                                                                                                                                                                         
system_time_zone                                                                                                                                    Yes                                                                                                                   Global                                                     No
table_cache                   Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
table_definition_cache        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
Table_locks_immediate                                                                                                                                                                                          Yes                                                        Both                                                       No
Table_locks_waited                                                                                                                                                                                             Yes                                                        Both                                                       No
table_lock_wait_timeout       Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
table_open_cache                                                                         Yes                                                        Yes                                                                                                                   Global                                                     Yes
table_type                                                                                                                                          Yes                                                                                                                   Both                                                       Yes
tc-heuristic-recover          Yes                                                        Yes                                                                                                                                                                                                                                         
Tc_log_max_pages_used                                                                                                                                                                                          Yes                                                        Both                                                       No
Tc_log_page_size                                                                                                                                                                                               Yes                                                        Both                                                       No
Tc_log_page_waits                                                                                                                                                                                              Yes                                                        Both                                                       No
temp-pool                     Yes                                                        Yes                                                                                                                                                                                                                                         
thread_cache_size             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
thread_concurrency            Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
thread_handling               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Threads_cached                                                                                                                                                                                                 Yes                                                        Both                                                       No
Threads_connected                                                                                                                                                                                              Yes                                                        Both                                                       No
Threads_created                                                                                                                                                                                                Yes                                                        Both                                                       No
Threads_running                                                                                                                                                                                                Yes                                                        Both                                                       No
thread_stack                  Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
timed_mutexes                 Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
time_format                   Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
timestamp                                                                                                                                           Yes                                                                                                                   Session                                                    Yes
time_zone                     Yes                                                                                                                   Yes                                                                                                                   Both                                                       Yes
tmpdir                        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
tmp_table_size                Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
transaction_alloc_block_size  Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
transaction_allow_batching                                                                                                                          Yes                                                                                                                   Session                                                    Yes
transaction-isolation         Yes                                                        Yes                                                                                                                                                                                                                                         
transaction_prealloc_size     Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
tx_isolation                                                                                                                                        Yes                                                                                                                   Both                                                       Yes
unique_checks                                                                                                                                       Yes                                                                                                                   Session                                                    Yes
updatable_views_with_limit    Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
Uptime                                                                                                                                                                                                         Yes                                                        Both                                                       No
Uptime_since_flush_status                                                                                                                                                                                      Yes                                                        Both                                                       No
user                          Yes                                                        Yes                                                                                                                                                                                                                                         
use-symbolic-links            Yes                                                        Yes                                                                                                                                                                                                                                         
verbose                       Yes                                                                                                                                                                                                                                                                                                    
version                       Yes                                                                                                                   Yes                                                                                                                   Global                                                     No
version_comment                                                                                                                                     Yes                                                                                                                   Global                                                     No
version_compile_machine                                                                                                                             Yes                                                                                                                   Global                                                     No
version_compile_os                                                                                                                                  Yes                                                                                                                   Global                                                     No
wait_timeout                  Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
warning_count                                                                                                                                       Yes                                                                                                                   Session                                                    No


File: manual.info,  Node: server-options,  Next: server-system-variables,  Prev: mysqld-option-tables,  Up: mysqld-server

5.1.2 Command Options
---------------------

When you start the `mysqld' server, you can specify program options
using any of the methods described in *Note program-options::. The most
common methods are to provide options in an option file or on the
command line.  However, in most cases it is desirable to make sure that
the server uses the same options each time it runs. The best way to
ensure this is to list them in an option file. See *Note option-files::.

MySQL Enterprise

For expert advice on setting command options, subscribe to the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

`mysqld' reads options from the `[mysqld]' and `[server]' groups.
`mysqld_safe' reads options from the `[mysqld]', `[server]',
`[mysqld_safe]', and `[safe_mysqld]' groups.  `mysql.server' reads
options from the `[mysqld]' and `[mysql.server]' groups.

An embedded MySQL server usually reads options from the `[server]',
`[embedded]', and `[XXXXX_SERVER]' groups, where XXXXX is the name of
the application into which the server is embedded.

`mysqld' accepts many command options. For a brief summary, execute
`mysqld --help'. To see the full list, use `mysqld --verbose --help'.

The following list shows some of the most common server options.
Additional options are described in other sections:

   * Options that affect security: See *Note privileges-options::.

   * SSL-related options: See *Note ssl-options::.

   * Binary log control options: See *Note binary-log::.

   * Replication-related options: See *Note replication-options::.

   * Options specific to particular storage engines: See *Note
     myisam-start::, *Note innodb-parameters::, and *Note
     mysql-cluster-mysqld-command-options::.

You can also set the values of server system variables by using
variable names as options, as described at the end of this section.

   *  `--help', `-?'

     Display a short help message and exit. Use both the `--verbose'
     and `--help' options to see the full message.

   *  `--abort-slave-event-count'

     *Value Set *         
     Typenumeric          
     Default0 Min Value0  

     When this option is set to some positive integer VALUE other than
     0 (the default) it affects replication behavior as follows: After
     the slave SQL thread has started, VALUE log events are allowed to
     be executed; after that, the slave SQL thread does not receive any
     more events, just as if the network connection from the master
     were cut. The slave thread continues to run, and the output from
     `SHOW SLAVE STATUS' displays `Yes' in both the `Slave_IO_Running'
     and the `Slave_SQL_Running' columns, but no further events are
     read from the relay log.

     This option is used internally by the MySQL test suite for
     replication testing and debugging. It is not intended for use in a
     production setting.

   *  `--allow-suspicious-udfs'

     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     This option controls whether user-defined functions that have only
     an `xxx' symbol for the main function can be loaded. By default,
     the option is off and only UDFs that have at least one auxiliary
     symbol can be loaded; this prevents attempts at loading functions
     from shared object files other than those containing legitimate
     UDFs. See *Note udf-security::.

   *  `--ansi'

     Use standard (ANSI) SQL syntax instead of MySQL syntax. For more
     precise control over the server SQL mode, use the `--sql-mode'
     option instead. See *Note ansi-mode::, and *Note server-sql-mode::.

   *  `--basedir=PATH', `-b PATH'

     *Option Sets         Yes, `basedir'
     Variable*            
     *Variable Name*      `basedir'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The path to the MySQL installation directory. All paths are
     usually resolved relative to this directory.

   *  `--big-tables'

     *Option Sets         Yes, `big_tables'
     Variable*            
     *Variable Name*      `big-tables'
     *Variable Scope*     Session
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          

     Allow large result sets by saving all temporary sets in files.
     This option prevents most `table full' errors, but also slows down
     queries for which in-memory tables would suffice. Since MySQL
     3.23.2, the server is able to handle large result sets
     automatically by using memory for small temporary tables and
     switching to disk tables where necessary.

   *  `--bind-address=IP'

     *Value Set *         
     Typestring           

     The IP address to bind to. Only one address can be selected.  If
     this option is specified multiple times, the last address given is
     used.

   *  `--binlog-format={ROW|STATEMENT|MIXED}'

     *Version Introduced* 5.1.5
     *Option Sets         Yes, `binlog_format'
     Variable*            
     *Variable Name*      `binlog_format'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set (<=       
     5.1.7, >= 5.1.5)*    
     Typeenumeration      
     DefaultSTATEMENT     
     Valid ValuesROW,     
     STATEMENT            
     *Value Set (<=       
     5.1.7, >= 5.1.5)*    
     Typeenumeration      
     DefaultSTATEMENT     
     Valid ValuesROW,     
     STATEMENT            
     *Value Set (<=       
     5.1.11, >= 5.1.8)*   
     Typeenumeration      
     DefaultSTATEMENT     
     Valid ValuesROW,     
     STATEMENT, MIXED     
     *Value Set (<=       
     5.1.11, >= 5.1.8)*   
     Typeenumeration      
     DefaultSTATEMENT     
     Valid ValuesROW,     
     STATEMENT, MIXED     
     *Value Set (>=       
     5.1.12)*             
     Typeenumeration      
     DefaultMIXED Valid   
     ValuesROW,           
     STATEMENT, MIXED     

     Specify whether to use row-based, statement-based, or mixed
     replication (statement-based was the default prior to MySQL
     5.1.12; beginning with MySQL 5.1.12, mixed replication is the
     default). See *Note replication-formats::.  This option was added
     in MySQL 5.1.5.

   *  `--binlog-row-event-max-size=N'

     *Version Introduced* 5.1.5
     *Value Set *         
     Typenumeric          
     Default1024 Min      
     Value256             

     Specify the maximum size of a row-based binary log event, in
     bytes. Rows are grouped into events smaller than this size if
     possible. The value should be a multiple of 256. The default is
     1024. See *Note replication-formats::.  This option was added in
     MySQL 5.1.5.

   *  `--bootstrap'

     This option is used by the `mysql_install_db' script to create the
     MySQL privilege tables without having to start a full MySQL server.

     This option is unavailable if MySQL was configured with the
     `--disable-grant-options' option. See *Note configure-options::.

   *  `--character-sets-dir=PATH'

     *Option Sets         Yes, `character_sets_dir'
     Variable*            
     *Variable Name*      `character-sets-dir'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The directory where character sets are installed. See *Note
     charset-configuration::.

   *  `--character-set-client-handshake'

     *Value Set *         
     Typeboolean          
     DefaultTRUE          

     Don't ignore character set information sent by the client.  To
     ignore client information and use the default server character
     set, use `--skip-character-set-client-handshake'; this makes MySQL
     behave like MySQL 4.0.

   *  `--character-set-filesystem=CHARSET_NAME'

     *Version Introduced* 5.1.6
     *Option Sets         Yes, `character_set_filesystem'
     Variable*            
     *Variable Name*      `character_set_filesystem'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     The filesystem character set. This option sets the
     `character_set_filesystem' system variable.  It was added in MySQL
     5.1.6.

   *  `--character-set-server=CHARSET_NAME', `-C CHARSET_NAME'

     *Option Sets         Yes, `character_set_server'
     Variable*            
     *Variable Name*      `character_set_server'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     Use CHARSET_NAME as the default server character set. See *Note
     charset-configuration::. If you use this option to specify a
     non-default character set, you should also use
     `--collation-server' to specify the collation.

   *  `--chroot=PATH', `-r PATH'

     *Value Set *         
     Typefilename         

     Put the `mysqld' server in a closed environment during startup by
     using the `chroot()' system call. This is a recommended security
     measure. Note that use of this option somewhat limits `LOAD DATA
     INFILE' and `SELECT ... INTO OUTFILE'.

   *  `--collation-server=COLLATION_NAME'

     *Option Sets         Yes, `collation_server'
     Variable*            
     *Variable Name*      `collation_server'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     Use COLLATION_NAME as the default server collation. See *Note
     charset-configuration::.

   *  `--console'

     *Option Sets         Yes, `console'
     Variable*            
     *Platform Specific*  windows

     (Windows only.) Write error log messages to `stderr' and `stdout'
     even if `--log-error' is specified.  `mysqld' does not close the
     console window if this option is used.

   *  `--core-file'

     *Value Set *         
     Typeboolean          
     DefaultTRUE          

     Write a core file if `mysqld' dies. For some systems, you must
     also specify the `--core-file-size' option to `mysqld_safe'. See
     *Note mysqld-safe::. Note that on some systems, such as Solaris,
     you do not get a core file if you are also using the `--user'
     option.

   *  `--datadir=PATH', `-h PATH'

     *Option Sets         Yes, `datadir'
     Variable*            
     *Variable Name*      `datadir'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The path to the data directory.

   *  `--debug[=DEBUG_OPTIONS]', `-# [DEBUG_OPTIONS]'

     *Variable Name*      `debug'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           
     Default'd:t:o,/tmp/mysqld.trace

     If MySQL is configured with `--with-debug', you can use this
     option to get a trace file of what `mysqld' is doing. The
     DEBUG_OPTIONS string often is `'d:t:o,FILE_NAME''.  The default is
     `'d:t:i:o,mysqld.trace''.  See MySQL Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

     As of MySQL 5.1.12, using `--with-debug' to configure MySQL with
     debugging support enables you to use the
     `--debug="d,parser_debug"' option when you start the server. This
     causes the Bison parser that is used to process SQL statements to
     dump a parser trace to the server's standard error output.
     Typically, this output is written to the error log.

     This option may be given multiple times. Values that begin with
     `+' or `-' are added to or subtracted from the previous value. For
     example, `--debug=T' `--debug=+P' sets the value to `P:T'.

   *  `--default-character-set=CHARSET_NAME' (_DEPRECATED_)

     *Deprecated*         5.0
     *Value Set *         
     Typestring           

     Use CHARSET_NAME as the default character set. This option is
     deprecated in favor of `--character-set-server'. See *Note
     charset-configuration::.

   *  `--default-collation=COLLATION_NAME'

     *Variable Name*      `default-collation'
     *Variable Scope*     
     *Dynamic Variable*   No
     *Deprecated*         4.1.3
     *Value Set *         
     Typestring           

     Use COLLATION_NAME as the default collation. This option is
     deprecated in favor of `--collation-server'. See *Note
     charset-configuration::.

   *  `--default-storage-engine=TYPE'

     Set the default storage engine (table type) for tables. See *Note
     storage-engines::.

   *  `--default-table-type=TYPE'

     *Deprecated*         5.0, by `default-storage-engine'
     *Value Set *         
     Typestring           

     This option is a synonym for `--default-storage-engine'.

   *  `--default-time-zone=TIMEZONE'

     *Value Set *         
     Typestring           

     Set the default server time zone. This option sets the global
     `time_zone' system variable. If this option is not given, the
     default time zone is the same as the system time zone (given by
     the value of the `system_time_zone' system variable.

   *  `--delay-key-write[={OFF|ON|ALL}]'

     *Option Sets         Yes, `delay_key_write'
     Variable*            
     *Variable Name*      `delay-key-write'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     DefaultON Valid      
     ValuesON, OFF, ALL   

     Specify how to use delayed key writes. Delayed key writing causes
     key buffers not to be flushed between writes for `MyISAM' tables.
     `OFF' disables delayed key writes. `ON' enables delayed key writes
     for those tables that were created with the `DELAY_KEY_WRITE'
     option.  `ALL' delays key writes for all `MyISAM' tables. See
     *Note server-parameters::, and *Note myisam-start::.

     *Note*:

     If you set this variable to `ALL', you should not use `MyISAM'
     tables from within another program (such as another MySQL server or
     `myisamchk') when the tables are in use.  Doing so leads to index
     corruption.

   *  `--des-key-file=FILE_NAME'

     Read the default DES keys from this file. These keys are used by
     the `DES_ENCRYPT()' and `DES_DECRYPT()' functions.

   *  `--disconnect-slave-event-count'

     *Value Set *         
     Typenumeric Default0 

     This option is used internally by the MySQL test suite for
     replication testing and debugging.

   *  `--enable-named-pipe'

     *Platform Specific*  windows

     Enable support for named pipes. This option applies only on
     Windows NT, 2000, XP, and 2003 systems. For MySQL 5.1.20 and
     earler, this option is available only when using the `mysqld-nt'
     and `mysqld-debug' servers that support named-pipe connections.
     For MySQL 5.1.21 and later, `mysqld-nt' is not available, but
     support is included in the standard `mysqld' and `mysqld-debug'
     servers.

   *  `--enable-pstack'

     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Print a symbolic stack trace on failure.

   *  `--engine-condition-pushdown={ON|OFF}'

     *Option Sets         Yes, `engine_condition_pushdown'
     Variable*            
     *Variable Name*      `engine_condition_pushdown'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set (>=       
     5.1.0)*              
     Typeboolean          
     DefaultON            

     When the value of this option is 0 (`OFF'), a query such as
     `SELECT * FROM t WHERE mycol = 42', where `mycol' is a non-indexed
     column, is executed as a full table scan. The storage engine sends
     every row to the MySQL server, which applies the `WHERE'
     condition. If `engine_condition_pushdown' is set to 1 (`ON'), the
     condition is `pushed down' to the storage engine, which uses the
     condition to perform the scan, and sends back to the MySQL server
     only those rows that match the condition. By default, this
     variable is `OFF'.

     In MySQL 5.1, this option is useful only with the `NDBCLUSTER'
     storage engine. However, we intend to implement it for additional
     storage engines in future MySQL releases.

     Setting this option to `ON' on a MySQL Server acting as a MySQL
     Cluster SQL node causes `WHERE' conditions on unindexed columns to
     be evaluated on the cluster's data nodes and only the rows that
     match to be sent back to the SQL node that issued the query. This
     means the amount of cluster data that must be sent over the
     network is greatly reduced, increasing the efficiency with which
     results are returned.

     For more information, see *Note condition-pushdown-optimization::.

   *  `--event-scheduler[=VALUE]'

     *Version Introduced* 5.1.6
     *Option Sets         Yes, `event-scheduler'
     Variable*            
     *Variable Name*      `event_scheduler'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     DefaultOFF Valid     
     ValuesON, OFF,       
     DISABLED             

     Enable or disable, and start or stop, the event scheduler.  This
     option was added in MySQL 5.1.6. Note that its permitted values
     and behaviour changed in MySQL 5.1.11, and again in MySQL 5.1.12.

     For detailed information, see The `event-scheduler' Option.

   *  `--exit-info[=FLAGS]', `-T [FLAGS]'

     *Value Set *         
     Typenumeric          

     This is a bit mask of different flags that you can use for
     debugging the `mysqld' server. Do not use this option unless you
     know _exactly_ what it does!

   *  `--external-locking'

     *Option Sets         Yes, `external_locking'
     Variable*            
     *Disabled by*        `skip-external-locking'
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Enable external locking (system locking), which is disabled by
     default as of MySQL 4.0. Note that if you use this option on a
     system on which `lockd' does not fully work (such as Linux), it is
     easy for `mysqld' to deadlock. This option previously was named
     `--enable-locking'.

     For more information about external locking, including conditions
     under which it can and cannot be used, see *Note
     external-locking::.

   *  `--flush'

     *Variable Name*      `flush'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultOFF           

     Flush (synchronize) all changes to disk after each SQL statement.
     Normally, MySQL does a write of all changes to disk only after
     each SQL statement and lets the operating system handle the
     synchronizing to disk. See *Note crashing::.

   *  `--gdb'

     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Install an interrupt handler for `SIGINT' (needed to stop `mysqld'
     with `^C' to set breakpoints) and disable stack tracing and core
     file handling. See MySQL Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

   *  `--general-log[={0|1}]'

     *Version Introduced* 5.1.12
     *Option Sets         Yes, `general_log'
     Variable*            
     *Variable Name*      `general_log'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultOFF           

     Specify the initial general log state, if the `--log' or `-l'
     option is given. With no argument or an argument of 0, the
     `--general-log' option disables the log. If omitted or given with
     an argument of 1, the option enables the log. If `--log' or `-l' is
     not specified, `--general-log' has no effect.  This option was
     added in MySQL 5.1.12.

   *  `--init-file=FILE_NAME'

     *Option Sets         Yes, `init_file'
     Variable*            
     *Variable Name*      `init_file'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     Read SQL statements from this file at startup. Each statement must
     be on a single line and should not include comments.

     This option is unavailable if MySQL was configured with the
     `--disable-grant-options' option. See *Note configure-options::.

   * `--innodb-XXX'

     The `InnoDB' options are listed in *Note innodb-parameters::.

   *  `--language=LANG_NAME, -L LANG_NAME'

     *Option Sets         Yes, `language'
     Variable*            
     *Variable Name*      `language'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         
     Default/usr/local/mysql/share/mysql/english/

     Return client error messages in the given language.  LANG_NAME can
     be given as the language name or as the full pathname to the
     directory where the language files are installed. See *Note
     error-message-language::.

   *  `--large-pages'

     *Option Sets         Yes, `large_pages'
     Variable*            
     *Variable Name*      `large_pages'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Platform Specific*  linux
     *Value Set *         
     Typelinuxboolean     
     DefaultFALSE         

     Some hardware/operating system architectures support memory pages
     greater than the default (usually 4KB). The actual implementation
     of this support depends on the underlying hardware and OS.
     Applications that perform a lot of memory accesses may obtain
     performance improvements by using large pages due to reduced
     Translation Lookaside Buffer (TLB) misses.

     Currently, MySQL supports only the Linux implementation of large
     pages support (which is called HugeTLB in Linux). We have plans to
     extend this support to FreeBSD, Solaris and possibly other
     platforms.

     Before large pages can be used on Linux, it is necessary to
     configure the HugeTLB memory pool. For reference, consult the
     `hugetlbpage.txt' file in the Linux kernel source.

     This option is disabled by default.

   *  `--log[=FILE_NAME]', `-l [FILE_NAME]'

     *Option Sets         Yes, `log'
     Variable*            
     *Variable Name*      `log'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           
     DefaultOFF           

     This option enables logging to the general query log, which
     contains entries that record client connections and SQL statements
     received from clients. The log output destination can be selected
     with the `--log-output' option as of MySQL 5.1.6. Before 5.1.6,
     logging occurs to the general query log file. If you omit the
     filename, MySQL uses `HOST_NAME.log' as the filename. See *Note
     log-tables::, and *Note query-log::.

   *  `--log-bin[=BASE_NAME]'

     *Value Set *         
     Typefilename         

     Enable binary logging. The server logs all statements that change
     data to the binary log, which is used for backup and replication.
     See *Note binary-log::.

     The option value, if given, is the basename for the log sequence.
     The server creates binary log files in sequence by adding a
     numeric suffix to the basename. It is recommended that you specify
     a basename (see *Note open-bugs::, for the reason). Otherwise,
     MySQL uses `HOST_NAME-bin' as the basename.

   *  `--log-bin-index[=FILE_NAME]'

     *Value Set *         
     Typefilename         

     The index file for binary log filenames. See *Note binary-log::.
     If you omit the filename, and if you didn't specify one with
     `--log-bin', MySQL uses `HOST_NAME-bin.index' as the filename.

   *  `--log-bin-trust-function-creators[={0|1}]'

     *Option Sets         Yes, `log_bin_trust_function_creators'
     Variable*            
     *Variable Name*      `log_bin_trust_function_creators'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     With no argument or an argument of 1, this option sets the
     `log_bin_trust_function_creators' system variable to 1. With an
     argument of 0, this option sets the system variable to 0.
     `log_bin_trust_function_creators' affects how MySQL enforces
     restrictions on stored function and trigger creation. See *Note
     stored-procedure-logging::.

   *  `--log-error[=FILE_NAME]'

     *Option Sets         Yes, `log_error'
     Variable*            
     *Variable Name*      `log_error'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     Log errors and startup messages to this file. See *Note
     error-log::. If you omit the filename, MySQL uses `HOST_NAME.err'.
     If the filename has no extension, the server adds an extension of
     `.err'.

   *  `--log-isam[=FILE_NAME]'

     *Value Set *         
     Typefilename         

     Log all `MyISAM' changes to this file (used only when debugging
     `MyISAM').

   *  `--log-long-format' (_DEPRECATED_)

     *Deprecated*         4.1

     Log extra information to the binary log and slow query log, if
     they have been activated. For example, the username and timestamp
     are logged for all queries. This option is deprecated, as it now
     represents the default logging behavior. (See the description for
     `--log-short-format'.) The `--log-queries-not-using-indexes'
     option is available for the purpose of logging queries that do not
     use indexes to the slow query log.

   *  `--log-output[=VALUE,...]'

     *Version Introduced* 5.1.6
     *Option Sets         Yes, `log_output'
     Variable*            
     *Variable Name*      `log_output'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     DefaultFILE Valid    
     ValuesTABLE, FILE,   
     NONE                 

     This option determines the destination for general query log and
     slow query log output. The option value can be given as one or
     more of the words `TABLE', `FILE', or `NONE'. If the option is
     given without a value, the default is `FILE'. (For MySQL 5.1.6
     through 5.1.20, the default is `TABLE'.)  `TABLE' select logging
     to the `general_log' and `slow_log' tables in the `mysql' database
     as a destination.  `FILE' selects logging to log files as a
     destination. (For `FILE' logging, the `--log' and `-slow-log'
     options determine the log file location.)  `NONE' disables
     logging. If `NONE' is present in the option value, it takes
     precedence over any other words that are present.  `TABLE' and
     `FILE' can both be given to select to both log output destinations.

     This option selects log output destinations, but does not enable
     log output. To do that, use the `--log' and `--log-slow-queries'
     options. For more information, see *Note log-tables::.

     The `--log-output' option was added in MySQL 5.1.6.

   *  `--log-queries-not-using-indexes'

     *Option Sets         Yes, `log_queries_not_using_indexes'
     Variable*            
     *Variable Name*      `log_queries_not_using_indexes'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          

     If you are using this option with `--log-slow-queries', queries
     that do not use indexes are logged to the slow query log. See
     *Note slow-query-log::.

   *  `--log-short-format'

     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Log less information to the binary log and slow query log, if they
     have been activated. For example, the username and timestamp are
     not logged for queries.

   *  `--log-slow-admin-statements'

     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Log slow administrative statements such as `OPTIMIZE TABLE',
     `ANALYZE TABLE', and `ALTER TABLE' to the slow query log.

   *  `--log-slow-queries[=FILE_NAME]'

     *Option Sets         Yes, `log_slow_queries'
     Variable*            
     *Variable Name*      `log_slow_queries'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          

     This option enables logging to the slow query log, which contains
     entries for all queries that have taken more than
     `long_query_time' seconds to execute. See the descriptions of the
     `--log-long-format' and `--log-short-format' options for details.

     The log output destination can be selected with the `--log-output'
     option as of MySQL 5.1.6.  Before 5.1.6, logging occurs to the
     slow query log file. If you omit the filename, MySQL uses
     `HOST_NAME-slow.log' as the filename. See *Note log-tables::, and
     *Note slow-query-log::.

   *  `--log-slow-slave-statements'

     *Version Introduced* 5.1.21
     *Value Set *         
     Typeboolean          
     Defaultoff           

     When the slow query log is enabled, this option enables logging
     for queries that have taken more than `long_query_time' seconds to
     execute on the slave.

     This option was added in MySQL 5.1.21.

   *  `--log-tc=FILE_NAME'

     *Value Set *         
     Typefilename         
     Defaulttc.log        

     The name of the memory-mapped transaction coordinator log file
     (for XA transactions that affect multiple storage engines when the
     binary log is disabled). The default name is `tc.log'. The file is
     created under the data directory if not given as a full pathname.
     Currently, this option is unused.

   *  `--log-tc-size=SIZE'

     *Value Set *         
     Typenumeric          
     Default24576 Max     
     Value4294967295      

     The size in bytes of the memory-mapped transaction coordinator
     log. The default size is 24KB.

   *  `--log-warnings[=LEVEL]', `-W [LEVEL]'

     *Option Sets         Yes, `log-warnings'
     Variable*            
     *Variable Name*      `log_warnings'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Disabled by*        `skip-log-warnings'
     *Value Set *         
     Typenumeric Default1 

     Print out warnings such as `Aborted connection...' to the error
     log. Enabling this option is recommended, for example, if you use
     replication (you get more information about what is happening,
     such as messages about network failures and reconnections). This
     option is enabled (1) by default, and the default LEVEL value if
     omitted is 1. To disable this option, use `--log-warnings=0'.  If
     the value is greater than 1, aborted connections are written to
     the error log. See *Note communication-errors::.

   *  `--low-priority-updates'

     *Option Sets         Yes, `low_priority_updates'
     Variable*            
     *Variable Name*      `low_priority_updates'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Give table-modifying operations (`INSERT', `REPLACE', `DELETE',
     `UPDATE') lower priority than selects. This can also be done via
     `{INSERT | REPLACE | DELETE | UPDATE} LOW_PRIORITY ...' to lower
     the priority of only one query, or by `SET LOW_PRIORITY_UPDATES=1'
     to change the priority in one thread. This affects only storage
     engines that use only table-level locking (`MyISAM', `MEMORY',
     `MERGE'). See *Note table-locking::.

   *  `--min-examined-row-limit=NUMBER'

     *Version Introduced* 5.1.21
     *Variable Name*      `min_examined_row_limit'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default0             
     Range0-4294967295    

     When this option is set, queries which examine fewer than NUMBER
     rows are not written to the slow query log. The default is 0.

     This option was introduced in MySQL 5.1.21.

   *  `--max-binlog-dump-events'

     *Value Set *         
     Typenumeric Default0 

     This option is used internally by the MySQL test suite for
     replication testing and debugging.

   *  `--memlock'

     *Variable Name*      `locked_in_memory'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Lock the `mysqld' process in memory. This option might help if you
     have a problem where the operating system is causing `mysqld' to
     swap to disk.

     `--memlock' works on systems that support the `mlockall()' system
     call; this includes Solaris as well as most Linux distributions
     that use a 2.4 or newer kernel. On Linux systems, you can tell
     whether or not `mlockall()' (and thus this option) is supported by
     checking to see whether or not it is defined in the system
     `mman.h' file, like this:

          shell> grep mlockall /usr/include/sys/mman.h

     If `mlockall()' is supported, you should see in the output of the
     previous command something like the following:

          extern int mlockall (int __flags) __THROW;

     *Important*:

     Using this option requires that you run the server as `root',
     which, for reasons of security, is normally not a good idea. See
     *Note changing-mysql-user::.

     You must not try to use this option on a system that does not
     support the `mlockall()' system call; if you do so, `mysqld' will
     very likely crash as soon as you try to start it.

   *  `--myisam-recover[=OPTION[,OPTION]...]]'

     *Value Set *         
     Typeenumeration      
     DefaultOFF Valid     
     ValuesDEFAULT,       
     BACKUP, FORCE, QUICK 

     Set the `MyISAM' storage engine recovery mode. The option value is
     any combination of the values of `DEFAULT', `BACKUP', `FORCE', or
     `QUICK'. If you specify multiple values, separate them by commas.
     Specifying the option with no argument is the same as specifying
     `DEFAULT', and specifying with an explicit value of `""' disables
     recovery (same as not giving the option). If recovery is enabled,
     each time `mysqld' opens a `MyISAM' table, it checks whether the
     table is marked as crashed or wasn't closed properly. (The last
     option works only if you are running with external locking
     disabled.) If this is the case, `mysqld' runs a check on the
     table. If the table was corrupted, `mysqld' attempts to repair it.

     The following options affect how the repair works:

     *Option*   *Description*
     `DEFAULT'  Recovery without backup, forcing, or quick
                checking.
     `BACKUP'   If the data file was changed during recovery,
                save a backup of the `TBL_NAME.MYD' file as
                `TBL_NAME-DATETIME.BAK'.
     `FORCE'    Run recovery even if we would lose more than
                one row from the `.MYD' file.
     `QUICK'    Don't check the rows in the table if there
                aren't any delete blocks.

     Before the server automatically repairs a table, it writes a note
     about the repair to the error log. If you want to be able to
     recover from most problems without user intervention, you should
     use the options `BACKUP,FORCE'. This forces a repair of a table
     even if some rows would be deleted, but it keeps the old data file
     as a backup so that you can later examine what happened.

     See *Note myisam-start::.

   *  `--old-passwords'

     *Option Sets         Yes, `old_passwords'
     Variable*            
     *Variable Name*      `old_passwords'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Force the server to generate short (pre-4.1) password hashes for
     new passwords. This is useful for compatibility when the server
     must support older client programs. See *Note password-hashing::.

   *  `--old-style-user-limits'

     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Enable old-style user limits. (Before MySQL 5.0.3, account
     resource limits were counted separately for each host from which a
     user connected rather than per account row in the `user' table.)
     See *Note user-resources::.

   *  `--one-thread'

     Only use one thread (for debugging under Linux). This option is
     available only if the server is built with debugging enabled. See
     MySQL Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

     As of MySQL 5.1.17, this option is deprecated; use
     `--thread_handling=one-thread' instead.

   *  `--open-files-limit=COUNT'

     *Option Sets         Yes, `open_files_limit'
     Variable*            
     *Variable Name*      `open_files_limit'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          
     Default0             
     Range0-65535         

     Changes the number of file descriptors available to `mysqld'. You
     should try increasing the value of this option if `mysqld' gives
     you the error `Too many open files'.  `mysqld' uses the option
     value to reserve descriptors with `setrlimit()'. If the requested
     number of file descriptors cannot be allocated, `mysqld' writes a
     warning to the error log.

     `mysqld' may attempt to allocate more than the requested number of
     descriptors (if they are available), using the values of
     `max_connections' and `table_open_cache' to estimate whether more
     descriptors will be needed.

   *  `--pid-file=PATH'

     *Option Sets         Yes, `pid_file'
     Variable*            
     *Variable Name*      `pid_file'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The pathname of the process ID file. This file is used by other
     programs such as `mysqld_safe' to determine the server's process
     ID.

   *  `--port=PORT_NUM', `-P PORT_NUM'

     *Option Sets         Yes, `port'
     Variable*            
     *Variable Name*      `port'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          
     Default3306          

     The port number to use when listening for TCP/IP connections. The
     port number must be 1024 or higher unless the server is started by
     the `root' system user.

   *  `--port-open-timeout=NUM'

     *Version Introduced* 5.1.5
     *Value Set *         
     Typenumeric Default0 

     On some systems, when the server is stopped, the TCP/IP port might
     not become available immediately. If the server is restarted
     quickly afterward, its attempt to reopen the port can fail. This
     option indicates how many seconds the server should wait for the
     TCP/IP port to become free if it cannot be opened. The default is
     not to wait. This option was added in MySQL 5.1.5.

   *  `--safe-mode'

     *Deprecated*         5.0

     Skip some optimization stages.

   *  `--safe-show-database' (_DEPRECATED_)

     *Option Sets         Yes, `safe_show_database'
     Variable*            
     *Variable Name*      `safe_show_database'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Deprecated*         4.0.2
     *Value Set *         
     Typeboolean          

     See *Note privileges-provided::.

   *  `--safe-user-create'

     *Option Sets         Yes, `safe-user-create'
     Variable*            
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     If this option is enabled, a user cannot create new MySQL users by
     using the `GRANT' statement unless the user has the `INSERT'
     privilege for the `mysql.user' table or any column in the table.
     If you want a user to have the ability to create new users that
     have those privileges that the user has the right to grant, you
     should grant the user the following privilege:

          GRANT INSERT(user) ON mysql.user TO 'USER_NAME'@'HOST_NAME';

     This ensures that the user cannot change any privilege columns
     directly, but has to use the `GRANT' statement to give privileges
     to other users.

   *  `--secure-auth'

     *Option Sets         Yes, `secure_auth'
     Variable*            
     *Variable Name*      `secure_auth'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Disallow authentication by clients that attempt to use accounts
     that have old (pre-4.1) passwords.

   *  `--secure-file-priv=PATH'

     *Version Introduced* 5.1.17
     *Option Sets         Yes, `secure_file_priv'
     Variable*            
     *Variable Name*      `secure_file_priv'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typestring           

     This option limits the effect of the `LOAD_FILE()' function and the
     `LOAD DATA' and `SELECT ... INTO OUTFILE' statements to work only
     with files in the specified directory.

     This option was added in MySQL 5.1.17.

   *  `--shared-memory'

     Enable shared-memory connections by local clients. This option is
     available only on Windows.

   *  `--shared-memory-base-name=NAME'

     The name of shared memory to use for shared-memory connections.
     This option is available only on Windows. The default name is
     `MYSQL'. The name is case sensitive.

   *  `--skip-concurrent-insert'

     Turn off the ability to select and insert at the same time on
     `MyISAM' tables. (This is to be used only if you think you have
     found a bug in this feature.) See *Note concurrent-inserts::.

   *  `--skip-external-locking'

     Do not use external locking (system locking). For more information
     about external locking, including conditions under which it can
     and cannot be used, see *Note external-locking::.

     External locking has been disabled by default since MySQL 4.0.

   *  `--skip-grant-tables'

     This option causes the server not to use the privilege system at
     all, which gives anyone with access to the server _unrestricted
     access to all databases_.  You can cause a running server to start
     using the grant tables again by executing `mysqladmin
     flush-privileges' or `mysqladmin reload' command from a system
     shell, or by issuing a MySQL `FLUSH PRIVILEGES' statement after
     connecting to the server. This option also suppresses loading of
     plugins and user-defined functions (UDFs).  Beginning with MySQL
     5.1.17, it also suppresses loading of scheduled events (Bug#28607
     (http://bugs.mysql.com/28607)).

     This option is unavailable if MySQL was configured with the
     `--disable-grant-options' option. See *Note configure-options::.

   *  `--skip-host-cache'

     Do not use the internal hostname cache for faster name-to-IP
     resolution. Instead, query the DNS server every time a client
     connects. See *Note dns::.

   *  `--skip-innodb'

     Disable the `InnoDB' storage engine. This saves memory and disk
     space and might speed up some operations. Do not use this option
     if you require `InnoDB' tables.

   *  `--skip-name-resolve'

     Do not resolve hostnames when checking client connections.  Use
     only IP numbers. If you use this option, all `Host' column values
     in the grant tables must be IP numbers or `localhost'. See *Note
     dns::.

   *  `--skip-networking'

     Don't listen for TCP/IP connections at all. All interaction with
     `mysqld' must be made via named pipes or shared memory (on
     Windows) or Unix socket files (on Unix). This option is highly
     recommended for systems where only local clients are allowed. See
     *Note dns::.

   *  `--sporadic-binlog-dump-fail'

     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     This option is used internally by the MySQL test suite for
     replication testing and debugging.

   * `--ssl*'

     Options that begin with `--ssl' specify whether to allow clients
     to connect via SSL and indicate where to find SSL keys and
     certificates. See *Note ssl-options::.

   *  `--standalone'

     *Platform Specific*  windows

     Available on Windows NT-based systems only; instructs the MySQL
     server not to run as a service.

   *  `--symbolic-links', `--skip-symbolic-links'

     Enable or disable symbolic link support. This option has different
     effects on Windows and Unix:

        * On Windows, enabling symbolic links allows you to establish a
          symbolic link to a database directory by creating a
          `DB_NAME.sym' file that contains the path to the real
          directory. See *Note windows-symbolic-links::.

        * On Unix, enabling symbolic links means that you can link a
          `MyISAM' index file or data file to another directory with
          the `INDEX DIRECTORY' or `DATA DIRECTORY' options of the
          `CREATE TABLE' statement. If you delete or rename the table,
          the files that its symbolic links point to also are deleted or
          renamed. See *Note symbolic-links-to-tables::.

   *  `--skip-safemalloc'

     If MySQL is configured with `--with-debug=full', all MySQL
     programs check for memory overruns during each memory allocation
     and memory freeing operation. This checking is very slow, so for
     the server you can avoid it when you don't need it by using the
     `--skip-safemalloc' option.

   *  `--skip-show-database'

     *Option Sets         Yes, `skip_show_database'
     Variable*            
     *Variable Name*      `skip_show_database'
     *Variable Scope*     Global
     *Dynamic Variable*   No

     With this option, the `SHOW DATABASES' statement is allowed only
     to users who have the `SHOW DATABASES' privilege, and the
     statement displays all database names. Without this option, `SHOW
     DATABASES' is allowed to all users, but displays each database
     name only if the user has the `SHOW DATABASES' privilege or some
     privilege for the database. Note that _any_ global privilege is
     considered a privilege for the database.

   *  `--skip-stack-trace'

     Don't write stack traces. This option is useful when you are
     running `mysqld' under a debugger. On some systems, you also must
     use this option to get a core file.  See MySQL Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

   *  `--skip-thread-priority'

     Disable using thread priorities for faster response time.

   *  `--slow-query-log[={0|1}]'

     *Version Introduced* 5.1.12
     *Option Sets         Yes, `slow_query_log'
     Variable*            
     *Variable Name*      `slow_query_log'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultOFF           

     Specify the initial slow query log state, if the
     `--log-slow-queries' option is given. With no argument or an
     argument of 0, the `--slow-query-log' option disables the log.  If
     omitted or given with an argument of 1, the option enables the
     log. If `--log' or `-l' is not specified, `--slow-query-log' has
     no effect. This option was added in MySQL 5.1.12.

   *  `--socket=PATH'

     *Option Sets         Yes, `socket'
     Variable*            
     *Variable Name*      `socket'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typelinuxfilename    
     Default/tmp/mysql.sock
     *Value Set *         
     Typehpuxfilename     
     Default/tmp/mysql.sock
     *Value Set *         
     Typesolarisfilename  
     Default/tmp/mysql.sock
     *Value Set *         
     Typemacosxfilename   
     Default/tmp/mysql.sock

     On Unix, this option specifies the Unix socket file to use when
     listening for local connections. The default value is
     `/tmp/mysql.sock'. On Windows, the option specifies the pipe name
     to use when listening for local connections that use a named pipe.
     The default value is `MySQL' (not case sensitive).

   *  `--sql-mode=VALUE[,VALUE[,VALUE...]]'

     *Option Sets         Yes, `sql_mode'
     Variable*            
     *Variable Name*      `sql_mode'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     Default" Valid       
     ValuesALLOW_INVALID_DATES,
     ANSI_QUOTES,         
     ERROR_FOR_DIVISION_BY_ZERO,
     HIGH_NOT_PRECEDENCE, 
     IGNORE_SPACE,        
     NO_AUTO_CREATE_USER, 
     NO_AUTO_VALUE_ON_ZERO,
     NO_BACKSLASH_ESCAPES,
     NO_DIR_IN_CREATE,    
     NO_ENGINE_SUBSTITUTION,
     NO_FIELD_OPTIONS,    
     NO_KEY_OPTIONS,      
     NO_TABLE_OPTIONS,    
     NO_UNSIGNED_SUBTRACTION,
     NO_ZERO_DATE,        
     NO_ZERO_IN_DATE,     
     ONLY_FULL_GROUP_BY,  
     PAD_CHAR_TO_FULL_LENGTH,
     PIPES_AS_CONCAT,     
     REAL_AS_FLOAT,       
     STRICT_ALL_TABLES,   
     STRICT_TRANS_TABLES  

     Set the SQL mode. See *Note server-sql-mode::.

   *  `--sysdate-is-now'

     *Version Introduced* 5.1.8
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     `SYSDATE()' by default returns the time at which it executes, not
     the time at which the statement in which it occurs begins
     executing. This differs from the behavior of `NOW()'.  This option
     causes `SYSDATE()' to be an alias for `NOW()'.  For information
     about the implications for binary logging and replication, see the
     description for `SYSDATE()' in *Note date-and-time-functions:: and
     for `SET TIMESTAMP' in *Note server-session-variables::.

     This option was added in MySQL 5.1.8.

   *  `--tc-heuristic-recover={COMMIT|ROLLBACK}'

     *Value Set *         
     Typeenumeration      
     Valid ValuesCOMMIT,  
     RECOVER              

     The type of decision to use in the heuristic recovery process.
     Currently, this option is unused.

   *  `--temp-pool'

     *Value Set *         
     Typeboolean          
     DefaultTRUE          

     This option causes most temporary files created by the server to
     use a small set of names, rather than a unique name for each new
     file. This works around a problem in the Linux kernel dealing with
     creating many new files with different names. With the old
     behavior, Linux seems to `leak' memory, because it is being
     allocated to the directory entry cache rather than to the disk
     cache.

   *  `--transaction-isolation=LEVEL'

     *Value Set *         
     Typeenumeration      
     Valid                
     ValuesREAD-UNCOMMTTED,
     READ-COMMITTED,      
     REPEATABLE-READ,     
     SERIALIZABLE         

     Sets the default transaction isolation level. The `level' value
     can be `READ-UNCOMMITTED', `READ-COMMITTED', `REPEATABLE-READ', or
     `SERIALIZABLE'. See *Note set-transaction::.

   *  `--tmpdir=PATH', `-t PATH'

     *Option Sets         Yes, `tmpdir'
     Variable*            
     *Variable Name*      `tmpdir'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The path of the directory to use for creating temporary files. It
     might be useful if your default `/tmp' directory resides on a
     partition that is too small to hold temporary tables. This option
     accepts several paths that are used in round-robin fashion.  Paths
     should be separated by colon characters (``:'') on Unix and
     semicolon characters (``;'') on Windows, NetWare, and OS/2. If the
     MySQL server is acting as a replication slave, you should not set
     `--tmpdir' to point to a directory on a memory-based filesystem or
     to a directory that is cleared when the server host restarts. For
     more information about the storage location of temporary files, see
     *Note temporary-files::. A replication slave needs some of its
     temporary files to survive a machine restart so that it can
     replicate temporary tables or `LOAD DATA INFILE' operations. If
     files in the temporary file directory are lost when the server
     restarts, replication fails.

   *  `--user={USER_NAME|USER_ID}', `-u {USER_NAME|USER_ID}'

     *Value Set *         
     Typestring           

     Run the `mysqld' server as the user having the name USER_NAME or
     the numeric user ID USER_ID.  (`User' in this context refers to a
     system login account, not a MySQL user listed in the grant tables.)

     This option is _mandatory_ when starting `mysqld' as `root'. The
     server changes its user ID during its startup sequence, causing it
     to run as that particular user rather than as `root'. See *Note
     security-guidelines::.

     To avoid a possible security hole where a user adds a
     `--user=root' option to a `my.cnf' file (thus causing the server to
     run as `root'), `mysqld' uses only the first `--user' option
     specified and produces a warning if there are multiple `--user'
     options. Options in `/etc/my.cnf' and `$MYSQL_HOME/my.cnf' are
     processed before command-line options, so it is recommended that
     you put a `--user' option in `/etc/my.cnf' and specify a value
     other than `root'. The option in `/etc/my.cnf' is found before any
     other `--user' options, which ensures that the server runs as a
     user other than `root', and that a warning results if any other
     `--user' option is found.

   *  `--version', `-V'

     Display version information and exit.

You can assign a value to a server system variable by using an option
of the form `--VAR_NAME=VALUE'.  For example, `--key_buffer_size=32M'
sets the `key_buffer_size' variable to a value of 32MB.

Note that when you assign a value to a variable, MySQL might
automatically correct the value to stay within a given range, or adjust
the value to the closest allowable value if only certain values are
allowed.

If you want to restrict the maximum value to which a variable can be
set at runtime with `SET', you can define this by using the
`--maximum-VAR_NAME=VALUE' command-line option.

You can change the values of most system variables for a running server
with the `SET' statement. See *Note set-option::.

*Note server-system-variables::, provides a full description for all
variables, and additional information for setting them at server
startup and runtime.  *Note server-parameters::, includes information on
optimizing the server by tuning system variables.


File: manual.info,  Node: server-system-variables,  Next: server-session-variables,  Prev: server-options,  Up: mysqld-server

5.1.3 System Variables
----------------------

The MySQL server maintains many system variables that indicate how it
is configured. Each system variable has a default value.  System
variables can be set at server startup using options on the command
line or in an option file. Most of them can be changed dynamically
while the server is running by means of the `SET' statement, which
enables you to modify operation of the server without having to stop
and restart it.  You can refer to system variable values in expressions.

There are several ways to see the names and values of system variables:

   * To see the values that a server will use based on its compiled-in
     defaults and any option files that it reads, use this command:

          mysqld --verbose --help

   * To see the values that a server will use based on its compiled-in
     defaults, ignoring the settings in any option files, use this
     command:

          mysqld --no-defaults --verbose --help

   * To see the current values used by a running server, use the `SHOW
     VARIABLES' statement.

This section provides a description of each system variable.  Variables
with no version indicated are present in all MySQL 5.1 releases. For
historical information concerning their implementation, please see
`MySQL 5.0 Reference Manual' and `MySQL 3.23, 4.0, 4.1 Reference
Manual'.

The following table lists all available system variables:

*Name*                        *Cmd-Line**Option *System *Var    *Dynamic*
                                      file*   Var*    Scope*  
autocommit                                    Yes     Session Yes
auto-increment-increment      Yes     Yes                     Yes
- _Variable_:                                 Yes     Both    Yes
auto_increment_increment                                      
auto-increment-offset         Yes     Yes                     Yes
- _Variable_:                                 Yes     Both    Yes
auto_increment_offset                                         
automatic_sp_privileges                       Yes     Global  Yes
back_log                      Yes     Yes     Yes     Global  No
basedir                       Yes     Yes     Yes     Global  No
big-tables                    Yes     Yes                     Yes
- _Variable_: big_tables                      Yes     Session Yes
binlog_cache_size             Yes     Yes     Yes     Global  Yes
binlog-format                 Yes     Yes                     Yes
- _Variable_: binlog_format                   Yes     Both    Yes
bulk_insert_buffer_size       Yes     Yes     Yes     Both    Yes
character_set_client                          Yes     Both    Yes
character_set_connection                      Yes     Both    Yes
character_set_database                        Yes     Both    Yes
character-set-filesystem      Yes     Yes                     Yes
- _Variable_:                                 Yes     Both    Yes
character_set_filesystem                                      
character_set_results                         Yes     Both    Yes
character-sets-dir            Yes     Yes                     No
- _Variable_:                                 Yes     Global  No
character_sets_dir                                            
character-set-server          Yes     Yes                     Yes
- _Variable_:                                 Yes     Both    Yes
character_set_server                                          
character_set_system                          Yes     Global  No
collation_connection                          Yes     Both    Yes
collation_database                            Yes     Both    Yes
collation-server              Yes     Yes                     Yes
- _Variable_:                                 Yes     Both    Yes
collation_server                                              
completion_type               Yes     Yes     Yes     Both    Yes
concurrent_insert             Yes     Yes     Yes     Global  Yes
connect_timeout               Yes     Yes     Yes     Global  Yes
datadir                       Yes     Yes     Yes     Global  No
date_format                                   Yes     Both    Yes
datetime_format               Yes     Yes     Yes     Both    Yes
debug                         Yes     Yes     Yes     Both    Yes
default_week_format           Yes     Yes     Yes     Both    Yes
delayed_insert_limit          Yes     Yes     Yes     Global  Yes
delayed_insert_timeout        Yes     Yes     Yes     Global  Yes
delayed_queue_size            Yes     Yes     Yes     Global  Yes
delay-key-write               Yes     Yes                     Yes
- _Variable_: delay_key_write                 Yes     Global  Yes
div_precision_increment       Yes     Yes     Yes     Both    Yes
engine-condition-pushdown     Yes     Yes                     Yes
- _Variable_:                                 Yes     Both    Yes
engine_condition_pushdown                                     
error_count                                   Yes     Session No
event-scheduler               Yes     Yes     Yes     Global  Yes
expire_logs_days              Yes     Yes     Yes     Global  Yes
flush                         Yes     Yes     Yes     Global  Yes
flush_time                    Yes     Yes     Yes     Global  Yes
foreign_key_checks                            Yes     Session Yes
ft_boolean_syntax             Yes     Yes     Yes     Global  Yes
ft_max_word_len               Yes     Yes     Yes     Global  No
ft_min_word_len               Yes     Yes     Yes     Global  No
ft_query_expansion_limit      Yes     Yes     Yes     Global  No
ft_stopword_file              Yes     Yes     Yes     Global  No
general-log                   Yes     Yes                     Yes
- _Variable_: general_log                     Yes     Global  Yes
general_log_file                              Yes     Global  Yes
group_concat_max_len          Yes     Yes     Yes     Both    Yes
have_archive                                  Yes     Global  No
have_blackhole_engine                         Yes     Global  No
have_compress                                 Yes     Global  No
have_crypt                                    Yes     Global  No
have_csv                                      Yes     Global  No
have_dynamic_loading                          Yes     Global  No
have_example_engine                           Yes     Global  No
have_federated_engine                         Yes     Global  No
have_geometry                                 Yes     Global  No
have_innodb                                   Yes     Global  No
have_isam                                     Yes     Global  No
have_merge_engine                             Yes     Global  No
have_ndbcluster                               Yes     Global  No
have_openssl                                  Yes     Global  No
have_partitioning                             Yes     Global  No
have_query_cache                              Yes     Global  No
have_raid                                     Yes     Global  No
have_row_based_replication                    Yes     Global  No
have_rtree_keys                               Yes     Global  No
have_ssl                                      Yes     Global  No
have_symlink                                  Yes     Global  No
hostname                                      Yes     Global  No
identity                                      Yes     Session Yes
init_connect                  Yes     Yes     Yes     Global  Yes
init-file                     Yes     Yes                     No
- _Variable_: init_file                       Yes     Global  No
init_slave                    Yes     Yes     Yes     Global  Yes
innodb_adaptive_hash_index    Yes     Yes     Yes     Global  No
innodb_additional_mem_pool_sizeYes     Yes     Yes     Global  No
innodb_autoextend_increment   Yes     Yes     Yes     Global  Yes
innodb_autoinc_lock_mode      Yes     Yes     Yes     Global  No
innodb_buffer_pool_awe_mem_mb Yes     Yes     Yes     Global  No
innodb_buffer_pool_size       Yes     Yes     Yes     Global  No
innodb_checksums              Yes     Yes     Yes     Global  No
innodb_commit_concurrency     Yes     Yes     Yes     Global  Yes
innodb_concurrency_tickets    Yes     Yes     Yes     Global  Yes
innodb_data_file_path         Yes     Yes     Yes     Global  No
innodb_data_home_dir          Yes     Yes     Yes     Global  No
innodb_doublewrite            Yes     Yes     Yes     Global  No
innodb_fast_shutdown          Yes     Yes     Yes     Global  Yes
innodb_file_io_threads        Yes     Yes     Yes     Global  No
innodb_file_per_table         Yes     Yes     Yes     Global  No
innodb_flush_log_at_trx_commitYes     Yes     Yes     Global  Yes
innodb_flush_method           Yes     Yes     Yes     Global  No
innodb_force_recovery         Yes     Yes     Yes     Global  No
innodb_locks_unsafe_for_binlogYes     Yes     Yes     Global  No
innodb_lock_wait_timeout      Yes     Yes     Yes     Global  No
innodb_log_arch_dir           Yes     Yes     Yes     Global  No
innodb_log_archive            Yes     Yes     Yes     Global  No
innodb_log_buffer_size        Yes     Yes     Yes     Global  No
innodb_log_files_in_group     Yes     Yes     Yes     Global  No
innodb_log_file_size          Yes     Yes     Yes     Global  No
innodb_log_group_home_dir     Yes     Yes     Yes     Global  No
innodb_max_dirty_pages_pct    Yes     Yes     Yes     Global  Yes
innodb_max_purge_lag          Yes     Yes     Yes     Global  Yes
innodb_mirrored_log_groups    Yes     Yes     Yes     Global  No
innodb_open_files             Yes     Yes     Yes     Global  No
innodb_rollback_on_timeout    Yes     Yes     Yes     Global  No
innodb_stats_on_metadata      Yes     Yes     Yes     Global  No
innodb_status_file            Yes     Yes     Yes     Global  No
innodb_support_xa             Yes     Yes     Yes     Both    Yes
innodb_sync_spin_loops        Yes     Yes     Yes     Global  Yes
innodb_table_locks            Yes     Yes     Yes     Both    Yes
innodb_thread_concurrency     Yes     Yes     Yes     Global  Yes
innodb_thread_sleep_delay     Yes     Yes     Yes     Global  Yes
insert_id                                     Yes     Session Yes
interactive_timeout           Yes     Yes     Yes     Both    Yes
join_buffer_size              Yes     Yes     Yes     Both    Yes
keep_files_on_create          Yes     Yes     Yes     Both    Yes
key_buffer_size               Yes     Yes     Yes     Global  Yes
key_cache_age_threshold       Yes     Yes     Yes     Global  Yes
key_cache_block_size          Yes     Yes     Yes     Global  Yes
key_cache_division_limit      Yes     Yes     Yes     Global  Yes
language                      Yes     Yes     Yes     Global  No
large-pages                   Yes     Yes                     No
- _Variable_: large_pages                     Yes     Global  No
large_page_size                               Yes     Global  No
last_insert_id                                Yes     Session Yes
lc_time_names                                 Yes     Both    Yes
license                                       Yes     Global  No
local_infile                                  Yes     Global  Yes
locked_in_memory                              Yes     Global  No
log                           Yes     Yes     Yes     Global  Yes
log_bin                                       Yes     Global  No
log-bin-trust-function-creatorsYes     Yes                     Yes
- _Variable_:                                 Yes     Global  Yes
log_bin_trust_function_creators                                
log-bin-trust-routine-creatorsYes     Yes                     Yes
- _Variable_:                                 Yes     Global  Yes
log_bin_trust_routine_creators                                
log-error                     Yes     Yes                     No
- _Variable_: log_error                       Yes     Global  No
log-output                    Yes     Yes                     Yes
- _Variable_: log_output                      Yes     Global  Yes
log-queries-not-using-indexes Yes     Yes                     Yes
- _Variable_:                                 Yes     Global  Yes
log_queries_not_using_indexes                                 
log-slave-updates             Yes     Yes                     No
- _Variable_:                                 Yes     Global  No
log_slave_updates                                             
log-slow-queries              Yes     Yes                     Yes
- _Variable_:                                 Yes     Global  Yes
log_slow_queries                                              
log-warnings                  Yes     Yes                     Yes
- _Variable_: log_warnings                    Yes     Both    Yes
long_query_time               Yes     Yes     Yes     Both    Yes
lower_case_file_system        Yes     Yes     Yes     Global  No
lower_case_table_names        Yes     Yes     Yes     Global  No
low-priority-updates          Yes     Yes                     Yes
- _Variable_:                                 Yes     Both    Yes
low_priority_updates                                          
*Note master-bind:            Yes     Yes     Yes             No
replication-options.                                          
max_allowed_packet            Yes     Yes     Yes     Both    Yes
max_binlog_cache_size         Yes     Yes     Yes     Global  Yes
max_binlog_size               Yes     Yes     Yes     Global  Yes
max_connect_errors            Yes     Yes     Yes     Global  Yes
max_connections               Yes     Yes     Yes     Global  Yes
max_delayed_threads           Yes     Yes     Yes     Both    Yes
max_error_count               Yes     Yes     Yes     Both    Yes
max_heap_table_size           Yes     Yes     Yes     Both    Yes
max_insert_delayed_threads                    Yes     Both    Yes
max_join_size                 Yes     Yes     Yes     Both    Yes
max_length_for_sort_data      Yes     Yes     Yes     Both    Yes
max_prepared_stmt_count       Yes     Yes     Yes     Global  Yes
max_relay_log_size            Yes     Yes     Yes     Global  Yes
max_seeks_for_key             Yes     Yes     Yes     Both    Yes
max_sort_length               Yes     Yes     Yes     Both    Yes
max_sp_recursion_depth        Yes     Yes     Yes     Both    Yes
max_tmp_tables                Yes     Yes     Yes     Both    Yes
max_user_connections          Yes     Yes     Yes     Both    Yes
max_write_lock_count          Yes     Yes     Yes     Global  Yes
memlock                       Yes     Yes     Yes     Global  No
min-examined-row-limit        Yes     Yes     Yes     Both    Yes
multi_range_count             Yes     Yes     Yes     Both    Yes
myisam_block_size             Yes     Yes     Yes     Both    Yes
myisam_data_pointer_size      Yes     Yes     Yes     Global  Yes
myisam_max_sort_file_size     Yes     Yes     Yes     Global  Yes
myisam_recover_options                        Yes     Global  No
myisam_repair_threads         Yes     Yes     Yes     Both    Yes
myisam_sort_buffer_size       Yes     Yes     Yes     Both    Yes
myisam_stats_method           Yes     Yes     Yes     Both    Yes
myisam_use_mmap               Yes     Yes     Yes     Global  Yes
named_pipe                                    Yes     Global  No
ndb_autoincrement_prefetch_sz Yes     Yes     Yes     Both    Yes
ndb_cache_check_time          Yes     Yes     Yes     Global  Yes
ndbcluster                    Yes     Yes     Yes     Both    Yes
ndb_extra_logging             Yes     Yes     Yes     Global  Yes
ndb_force_send                Yes     Yes     Yes     Both    Yes
*Note ndb_log_orig:                           Yes     Global  No
mysql-cluster-replication-schema.                                
ndb_log_update_as_write       Yes     Yes     Yes     Global  Yes
ndb_log_updated_only          Yes     Yes     Yes     Global  Yes
ndb_optimization_delay                        Yes     Global  Yes
ndb_table_no_logging                          Yes     Session Yes
ndb_table_temporary                           Yes     Session Yes
ndb_use_copying_alter_table                   Yes     Both    No
ndb_use_exact_count                           Yes     Both    Yes
ndb_wait_connected            Yes     Yes     Yes             No
net_buffer_length             Yes     Yes     Yes     Both    Yes
net_read_timeout              Yes     Yes     Yes     Both    Yes
net_retry_count               Yes     Yes     Yes     Both    Yes
net_write_timeout             Yes     Yes     Yes     Both    Yes
new                           Yes     Yes     Yes     Both    Yes
old                           Yes     Yes     Yes     Global  No
old-passwords                 Yes     Yes                     Yes
- _Variable_: old_passwords                   Yes     Both    Yes
open-files-limit              Yes     Yes                     No
- _Variable_:                                 Yes     Global  No
open_files_limit                                              
optimizer_prune_level         Yes     Yes     Yes     Both    Yes
optimizer_search_depth        Yes     Yes     Yes     Both    Yes
pid-file                      Yes     Yes                     No
- _Variable_: pid_file                        Yes     Global  No
plugin_dir                    Yes     Yes     Yes     Global  No
plugin_innodb_additional_mem_pool_sizeYes     Yes     Yes     Both    No
plugin_innodb_autoextend_incrementYes     Yes     Yes     Both    Yes
plugin_innodb_buffer_pool_awe_mem_mbYes     Yes                     No
- _Variable_:                                 Yes     Both    No
innodb_buffer_pool_awe_mem_mb                                 
plugin_innodb_buffer_pool_sizeYes     Yes     Yes     Both    No
plugin_innodb_checksums       Yes     Yes     Yes     Both    Yes
plugin_innodb_commit_concurrencyYes     Yes     Yes     Global  Yes
plugin_innodb_concurrency_ticketsYes     Yes     Yes     Global  Yes
plugin_innodb_data_file_path  Yes     Yes     Yes     Global  No
plugin_innodb_data_home_dir   Yes     Yes     Yes     Global  No
plugin-innodb-doublewrite     Yes     Yes                     No
- _Variable_:                                 Yes     Global  No
plugin_innodb_doublewrite                                     
plugin_innodb_fast_shutdown   Yes     Yes     Yes     Global  No
plugin_innodb_file_io_threads Yes     Yes     Yes     Global  No
plugin_innodb_file_per_table  Yes     Yes     Yes     Global  No
plugin_innodb_flush_log_at_trx_commitYes     Yes     Yes     Global  Yes
plugin_innodb_flush_method    Yes     Yes     Yes     Global  No
plugin_innodb_force_recovery  Yes     Yes     Yes     Global  No
plugin_innodb_locks_unsafe_for_binlogYes     Yes     Yes     Global  No
plugin_innodb_lock_wait_timeoutYes     Yes     Yes     Global  No
plugin_innodb_log_archive     Yes     Yes     Yes     Global  No
plugin_innodb_log_buffer_size Yes     Yes     Yes     Global  No
plugin_innodb_log_files_in_groupYes     Yes     Yes     Global  No
plugin_innodb_log_file_size   Yes     Yes     Yes     Global  No
plugin_innodb_log_group_home_dirYes     Yes     Yes     Global  No
plugin_innodb_max_dirty_pages_pctYes     Yes     Yes     Global  Yes
plugin_innodb_max_purge_lag   Yes     Yes     Yes     Global  Yes
plugin_innodb_mirrored_log_groupsYes     Yes     Yes     Global  No
plugin_innodb_open_files      Yes     Yes     Yes     Global  No
plugin_innodb_rollback_on_timeoutYes     Yes     Yes             No
plugin_innodb_stats_on_metadataYes     Yes     Yes             No
plugin_innodb_status_file     Yes     Yes     Yes             No
plugin_innodb_support_xa      Yes     Yes     Yes     Both    Yes
plugin_innodb_sync_spin_loops Yes     Yes     Yes     Global  Yes
plugin_innodb_table_locks     Yes     Yes     Yes     Both    Yes
plugin_innodb_thread_concurrencyYes     Yes     Yes     Global  Yes
plugin_innodb_thread_sleep_delayYes     Yes     Yes     Global  Yes
port                          Yes     Yes     Yes     Global  No
preload_buffer_size           Yes     Yes     Yes     Both    Yes
prepared_stmt_count                           Yes     Global  No
protocol_version                              Yes     Global  No
query_alloc_block_size        Yes     Yes     Yes     Both    Yes
query_cache_limit             Yes     Yes     Yes     Global  Yes
query_cache_min_res_unit      Yes     Yes     Yes     Global  Yes
query_cache_size              Yes     Yes     Yes     Global  Yes
query_cache_type              Yes     Yes     Yes     Both    Yes
query_cache_wlock_invalidate  Yes     Yes     Yes     Both    Yes
query_prealloc_size           Yes     Yes     Yes     Both    Yes
range_alloc_block_size        Yes     Yes     Yes     Both    Yes
read_buffer_size              Yes     Yes     Yes     Both    Yes
read_only                     Yes     Yes     Yes     Global  Yes
read_rnd_buffer_size          Yes     Yes     Yes     Both    Yes
relay_log_purge               Yes     Yes     Yes     Global  Yes
relay_log_space_limit         Yes     Yes     Yes     Global  No
report-host                   Yes     Yes                     No
- _Variable_: report_host                     Yes     Global  No
report-password               Yes     Yes                     No
- _Variable_: report_password                 Yes     Global  No
report-port                   Yes     Yes                     No
- _Variable_: report_port                     Yes     Global  No
report-user                   Yes     Yes                     No
- _Variable_: report_user                     Yes     Global  No
*Note rpl_recovery_rank:                      Yes     Global  Yes
replication-options.                                          
secure-auth                   Yes     Yes                     Yes
- _Variable_: secure_auth                     Yes     Global  Yes
secure-file-priv              Yes     Yes                     No
- _Variable_:                                 Yes     Global  No
secure_file_priv                                              
server-id                     Yes     Yes                     Yes
- _Variable_: server_id                       Yes     Global  Yes
shared_memory                                 Yes     Global  No
shared_memory_base_name                       Yes     Global  No
skip-external-locking         Yes     Yes                     No
- _Variable_:                                 Yes     Global  No
skip_external_locking                                         
skip-networking               Yes     Yes                     No
- _Variable_: skip_networking                 Yes     Global  No
skip-show-database            Yes     Yes                     No
- _Variable_:                                 Yes     Global  No
skip_show_database                                            
*Note slave-allow-batching:   Yes                             Yes
mysql-cluster-replication-starting.                                
- _Variable_:                                 Yes     Global  Yes
slave_allow_batching                                          
slave_compressed_protocol     Yes     Yes     Yes     Global  Yes
slave_exec_mode                               Yes     Global  Yes
*Note slave-load-tmpdir:      Yes     Yes                     No
replication-options.                                          
- _Variable_:                                 Yes     Global  No
slave_load_tmpdir                                             
*Note slave-net-timeout:      Yes     Yes                     Yes
replication-options.                                          
- _Variable_:                                 Yes     Global  Yes
slave_net_timeout                                             
*Note slave-skip-errors:      Yes     Yes                     No
replication-options.                                          
- _Variable_:                                 Yes     Global  No
slave_skip_errors                                             
slave_transaction_retries     Yes     Yes     Yes     Global  Yes
slow_launch_time              Yes     Yes     Yes     Global  Yes
slow-query-log                Yes     Yes                     Yes
- _Variable_: slow_query_log                  Yes     Global  Yes
slow_query_log_file                           Yes     Global  Yes
socket                        Yes     Yes     Yes     Global  No
sort_buffer_size              Yes     Yes     Yes     Both    Yes
sql_auto_is_null                              Yes     Session Yes
sql_big_selects                               Yes     Session Yes
sql_big_tables                                Yes     Session Yes
sql_buffer_result                             Yes     Session Yes
sql_log_bin                                   Yes     Session Yes
sql_log_off                                   Yes     Session Yes
sql_log_update                                Yes     Session Yes
sql_low_priority_updates                      Yes     Both    Yes
sql_max_join_size                             Yes     Both    Yes
sql-mode                      Yes     Yes                     Yes
- _Variable_: sql_mode                        Yes     Both    Yes
sql_notes                                     Yes     Session Yes
sql_quote_show_create                         Yes     Session Yes
sql_safe_updates                              Yes     Session Yes
sql_select_limit                              Yes     Both    Yes
sql_slave_skip_counter                        Yes     Global  Yes
sql_warnings                                  Yes     Session Yes
ssl-ca                        Yes     Yes                     No
- _Variable_: ssl_ca                          Yes     Global  No
ssl-capath                    Yes     Yes                     No
- _Variable_: ssl_capath                      Yes     Global  No
ssl-cert                      Yes     Yes                     No
- _Variable_: ssl_cert                        Yes     Global  No
ssl-cipher                    Yes     Yes                     No
- _Variable_: ssl_cipher                      Yes     Global  No
ssl-key                       Yes     Yes                     No
- _Variable_: ssl_key                         Yes     Global  No
storage_engine                                Yes     Both    Yes
sync-binlog                   Yes     Yes                     Yes
- _Variable_: sync_binlog                     Yes     Global  Yes
sync-frm                      Yes     Yes                     Yes
- _Variable_: sync_frm                        Yes     Global  Yes
system_time_zone                              Yes     Global  No
table_cache                   Yes     Yes     Yes     Global  Yes
table_definition_cache        Yes     Yes     Yes     Global  Yes
table_lock_wait_timeout       Yes     Yes     Yes     Global  Yes
table_open_cache                      Yes     Yes     Global  Yes
table_type                                    Yes     Both    Yes
thread_cache_size             Yes     Yes     Yes     Global  Yes
thread_concurrency            Yes     Yes     Yes     Global  No
thread_handling               Yes     Yes     Yes     Global  No
thread_stack                  Yes     Yes     Yes     Global  No
timed_mutexes                 Yes     Yes     Yes     Global  Yes
time_format                   Yes     Yes     Yes     Both    Yes
timestamp                                     Yes     Session Yes
time_zone                     Yes             Yes     Both    Yes
tmpdir                        Yes     Yes     Yes     Global  No
tmp_table_size                Yes     Yes     Yes     Both    Yes
transaction_alloc_block_size  Yes     Yes     Yes     Both    Yes
transaction_allow_batching                    Yes     Session Yes
transaction_prealloc_size     Yes     Yes     Yes     Both    Yes
tx_isolation                                  Yes     Both    Yes
unique_checks                                 Yes     Session Yes
updatable_views_with_limit    Yes     Yes     Yes     Both    Yes
version                       Yes             Yes     Global  No
version_comment                               Yes     Global  No
version_compile_machine                       Yes     Global  No
version_compile_os                            Yes     Global  No
wait_timeout                  Yes     Yes     Yes     Both    Yes
warning_count                                 Yes     Session No

For additional system variable information, see these sections:

   * *Note server-session-variables::, describes system variables that
     exist only as session variables (that is, they do not have any
     global counterpart).

   * *Note using-system-variables::, discusses the syntax for setting
     and displaying system variable values.

   * *Note dynamic-system-variables::, lists the variables that can be
     set at runtime.

   * Information on tuning system variables can be found in *Note
     server-parameters::.

   * *Note innodb-parameters::, lists `InnoDB' system variables.

*Note*:

Some of the following variable descriptions refer to `enabling' or
`disabling' a variable. These variables can be enabled with the `SET'
statement by setting them to `ON' or `1', or disabled by setting them
to `OFF' or `0'. However, to set such a variable on the command line or
in an option file, you must set it to `1' or `0'; setting it to `ON' or
`OFF' will not work.  For example, on the command line,
`--delay_key_write=1' works but `--delay_key_write=ON' does not.

Values for buffer sizes, lengths, and stack sizes are given in bytes
unless otherwise specified.

   *  `auto_increment_increment'

     *Option Sets         Yes, `auto_increment_increment'
     Variable*            
     *Variable Name*      `auto_increment_increment'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default1             
     Range1-65535         

     `auto_increment_increment' and `auto_increment_offset' are
     intended for use with master-to-master replication, and can be
     used to control the operation of `AUTO_INCREMENT' columns. Both
     variables have global and session values, and each can assume an
     integer value between 1 and 65,535 inclusive. Setting the value of
     either of these two variables to 0 causes its value to be set to 1
     instead.  Attempting to set the value of either of these two
     variables to an integer greater than 65,535 or less than 0 causes
     its value to be set to 65,535 instead. Attempting to set the value
     of `auto_increment_increment' or `auto_increment_offset' to a
     non-integer value gives rise to an error, and the actual value of
     the variable remains unchanged.

     *Important*:

     `auto_increment_increment' and `auto_increment_offset' are not
     intended for use with MySQL Cluster replication. Attempting to set
     them in a Cluster replication scenario may give rise to
     unpredictable (and unrecoverable) errors. The use of these
     variables with Cluster replication is therefore not supported.

     These two variables affect `AUTO_INCREMENT' column behavior as
     follows:

        * `auto_increment_increment' controls the interval between
          successive column values. For example:

               mysql> SHOW VARIABLES LIKE 'auto_inc%';
               +--------------------------+-------+
               | Variable_name            | Value |
               +--------------------------+-------+
               | auto_increment_increment | 1     |
               | auto_increment_offset    | 1     |
               +--------------------------+-------+
               2 rows in set (0.00 sec)

               mysql> CREATE TABLE autoinc1
                   -> (col INT NOT NULL AUTO_INCREMENT PRIMARY KEY);
                 Query OK, 0 rows affected (0.04 sec)

               mysql> SET @@auto_increment_increment=10;
               Query OK, 0 rows affected (0.00 sec)

               mysql> SHOW VARIABLES LIKE 'auto_inc%';
               +--------------------------+-------+
               | Variable_name            | Value |
               +--------------------------+-------+
               | auto_increment_increment | 10    |
               | auto_increment_offset    | 1     |
               +--------------------------+-------+
               2 rows in set (0.01 sec)

               mysql> INSERT INTO autoinc1 VALUES (NULL), (NULL), (NULL), (NULL);
               Query OK, 4 rows affected (0.00 sec)
               Records: 4  Duplicates: 0  Warnings: 0

               mysql> SELECT col FROM autoinc1;
               +-----+
               | col |
               +-----+
               |   1 |
               |  11 |
               |  21 |
               |  31 |
               +-----+
               4 rows in set (0.00 sec)

          (Note how `SHOW VARIABLES' is used here to obtain the current
          values for these variables.)

        * `auto_increment_offset' determines the starting point for the
          `AUTO_INCREMENT' column value. Consider the following,
          assuming that these statements are executed during the same
          session as the example given in the description for
          `auto_increment_increment':

               mysql> SET @@auto_increment_offset=5;
               Query OK, 0 rows affected (0.00 sec)

               mysql> SHOW VARIABLES LIKE 'auto_inc%';
               +--------------------------+-------+
               | Variable_name            | Value |
               +--------------------------+-------+
               | auto_increment_increment | 10    |
               | auto_increment_offset    | 5     |
               +--------------------------+-------+
               2 rows in set (0.00 sec)

               mysql> CREATE TABLE autoinc2
                   -> (col INT NOT NULL AUTO_INCREMENT PRIMARY KEY);
               Query OK, 0 rows affected (0.06 sec)

               mysql> INSERT INTO autoinc2 VALUES (NULL), (NULL), (NULL), (NULL);
               Query OK, 4 rows affected (0.00 sec)
               Records: 4  Duplicates: 0  Warnings: 0

               mysql> SELECT col FROM autoinc2;
               +-----+
               | col |
               +-----+
               |   5 |
               |  15 |
               |  25 |
               |  35 |
               +-----+
               4 rows in set (0.02 sec)

          If the value of `auto_increment_offset' is greater than that
          of `auto_increment_increment', the value of
          `auto_increment_offset' is ignored.

     Should one or both of these variables be changed and then new rows
     inserted into a table containing an `AUTO_INCREMENT' column, the
     results may seem counterintuitive because the series of
     `AUTO_INCREMENT' values is calculated without regard to any values
     already present in the column, and the next value inserted is the
     least value in the series that is greater than the maximum
     existing value in the `AUTO_INCREMENT' column. In other words, the
     series is calculated like so:

     `auto_increment_offset + N x auto_increment_increment'

     where N is a positive integer value in the series [1, 2, 3, ...].
     For example:

          mysql> SHOW VARIABLES LIKE 'auto_inc%';
          +--------------------------+-------+
          | Variable_name            | Value |
          +--------------------------+-------+
          | auto_increment_increment | 10    |
          | auto_increment_offset    | 5     |
          +--------------------------+-------+
          2 rows in set (0.00 sec)

          mysql> SELECT col FROM autoinc1;
          +-----+
          | col |
          +-----+
          |   1 |
          |  11 |
          |  21 |
          |  31 |
          +-----+
          4 rows in set (0.00 sec)

          mysql> INSERT INTO autoinc1 VALUES (NULL), (NULL), (NULL), (NULL);
          Query OK, 4 rows affected (0.00 sec)
          Records: 4  Duplicates: 0  Warnings: 0

          mysql> SELECT col FROM autoinc1;
          +-----+
          | col |
          +-----+
          |   1 |
          |  11 |
          |  21 |
          |  31 |
          |  35 |
          |  45 |
          |  55 |
          |  65 |
          +-----+
          8 rows in set (0.00 sec)

     The values shown for `auto_increment_increment' and
     `auto_increment_offset' generate the series 5 + N x 10, that is,
     [5, 15, 25, 35, 45, ...]. The greatest value present in the `col'
     column prior to the `INSERT' is 31, and the next available value
     in the `AUTO_INCREMENT' series is 35, so the inserted values for
     `col' begin at that point and the results are as shown for the
     `SELECT' query.

     It is not possible to confine the effects of these two variables
     to a single table, and thus they do not take the place of the
     sequences offered by some other database management systems; these
     variables control the behavior of all `AUTO_INCREMENT' columns in
     _all_ tables on the MySQL server. If the global value of either
     variable is set, its effects persist until the global value is
     changed or overridden by setting the session value, or until
     `mysqld' is restarted. If the local value is set, the new value
     affects `AUTO_INCREMENT' columns for all tables into which new
     rows are inserted by the current user for the duration of the
     session, unless the values are changed during that session.

     The default value of `auto_increment_increment' is 1. See *Note
     replication-features-auto-increment::.

     `auto_increment_increment' is supported for use with `NDB' tables
     beginning with MySQL 5.1.20. Previously, setting it when using
     MySQL Cluster tables or MySQL Cluster Replication produced
     unpredictable results.

   *  `auto_increment_offset'

     *Option Sets         Yes, `auto_increment_offset'
     Variable*            
     *Variable Name*      `auto_increment_offset'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default1             
     Range1-65535         

     This variable has a default value of 1. For particulars, see the
     description for `auto_increment_increment'.

     `auto_increment_offset' is supported for use with `NDB' tables
     beginning with MySQL 5.1.20. Previously, setting it when using
     MySQL Cluster tables or MySQL Cluster Replication produced
     unpredictable results.

   *  `automatic_sp_privileges'

     *Variable Name*      `automatic_sp_privileges'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultTRUE          

     When this variable has a value of 1 (the default), the server
     automatically grants the `EXECUTE' and `ALTER ROUTINE' privileges
     to the creator of a stored routine, if the user cannot already
     execute and alter or drop the routine. (The `ALTER ROUTINE'
     privilege is required to drop the routine.) The server also
     automatically drops those privileges when the creator drops the
     routine. If `automatic_sp_privileges' is 0, the server does not
     automatically add or drop these privileges.

   *  `back_log'

     *Option Sets         Yes, `back_log'
     Variable*            
     *Variable Name*      `back_log'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          
     Default50            
     Range1-65535         

     The number of outstanding connection requests MySQL can have. This
     comes into play when the main MySQL thread gets very many
     connection requests in a very short time. It then takes some time
     (although very little) for the main thread to check the connection
     and start a new thread. The `back_log' value indicates how many
     requests can be stacked during this short time before MySQL
     momentarily stops answering new requests. You need to increase
     this only if you expect a large number of connections in a short
     period of time.

     In other words, this value is the size of the listen queue for
     incoming TCP/IP connections. Your operating system has its own
     limit on the size of this queue. The manual page for the Unix
     `listen()' system call should have more details. Check your OS
     documentation for the maximum value for this variable. `back_log'
     cannot be set higher than your operating system limit.

   * `basedir'

     *Option Sets         Yes, `basedir'
     Variable*            
     *Variable Name*      `basedir'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The MySQL installation base directory. This variable can be set
     with the `--basedir' option. Relative pathnames for other
     variables usually are resolved relative to the base directory.

   *  `binlog_cache_size'

     *Option Sets         Yes, `binlog_cache_size'
     Variable*            
     *Variable Name*      `binlog_cache_size'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default32768         
     Range4096-4294967295 

     The size of the cache to hold the SQL statements for the binary
     log during a transaction. A binary log cache is allocated for each
     client if the server supports any transactional storage engines
     and if the server has the binary log enabled (`--log-bin' option).
     If you often use large, multiple-statement transactions, you can
     increase this cache size to get more performance. The
     `Binlog_cache_use' and `Binlog_cache_disk_use' status variables
     can be useful for tuning the size of this variable. See *Note
     binary-log::.

     MySQL Enterprise

     For recommendations on the optimum setting for `binlog_cache_size'
     subscribe to the MySQL Enterprise Monitor. For more information,
     see `http://www.mysql.com/products/enterprise/advisors.html'.

   *  `binlog_format'

     *Version Introduced* 5.1.5
     *Option Sets         Yes, `binlog_format'
     Variable*            
     *Variable Name*      `binlog_format'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set (<=       
     5.1.7, >= 5.1.5)*    
     Typeenumeration      
     DefaultSTATEMENT     
     Valid ValuesROW,     
     STATEMENT            
     *Value Set (<=       
     5.1.7, >= 5.1.5)*    
     Typeenumeration      
     DefaultSTATEMENT     
     Valid ValuesROW,     
     STATEMENT            
     *Value Set (<=       
     5.1.11, >= 5.1.8)*   
     Typeenumeration      
     DefaultSTATEMENT     
     Valid ValuesROW,     
     STATEMENT, MIXED     
     *Value Set (<=       
     5.1.11, >= 5.1.8)*   
     Typeenumeration      
     DefaultSTATEMENT     
     Valid ValuesROW,     
     STATEMENT, MIXED     
     *Value Set (>=       
     5.1.12)*             
     Typeenumeration      
     DefaultMIXED Valid   
     ValuesROW,           
     STATEMENT, MIXED     

     The binary logging format, either `STATEMENT', `ROW', or `MIXED'.
     `binlog_format' is set by the `--binlog-format' option at startup,
     or by the `binlog_format' variable at runtime (you need the
     `SUPER' privilege to set this variable on a global scope). See
     *Note replication-formats::. The startup variable was added in
     MySQL 5.1.5, and the runtime variable in MySQL 5.1.8. `MIXED' was
     added in MySQL 5.1.8.

     `STATEMENT' was used by default prior to MySQL 5.1.12; beginning
     with MySQL 5.1.12, `MIXED' is the default. When `MIXED' is
     specified, statement-based replication is used, except for cases
     where only row-based replication is guaranteed to lead to proper
     results. For example, this is the case when statements contain
     user-defined functions (UDF) or the `UUID()' function. An
     exception to this rule is that `MIXED' always uses statement-based
     replication for stored functions and triggers.

     There are exceptions when you cannot switch the replication format
     at runtime:

        * From within a stored function or a trigger.

        * If `NDB' is enabled.

        * If the session is currently in row-based replication mode and
          has open temporary tables.

     Trying to switch the format in those cases results in an error.

     Before MySQL 5.1.8, switching to row-based replication format
     would implicitly set `--log-bin-trust-function-creators=1' and
     `--innodb_locks_unsafe_for_binlog'. MySQL 5.1.8 and later no
     longer implicitly set these options when row-based replication is
     used.

   *  `bulk_insert_buffer_size'

     *Option Sets         Yes, `bulk_insert_buffer_size'
     Variable*            
     *Variable Name*      `bulk_insert_buffer_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default8388608       
     Range0-4294967295    

     `MyISAM' uses a special tree-like cache to make bulk inserts
     faster for `INSERT ...  SELECT', `INSERT ... VALUES (...), (...),
     ...', and `LOAD DATA INFILE' when adding data to non-empty tables.
     This variable limits the size of the cache tree in bytes per
     thread. Setting it to 0 disables this optimization. The default
     value is 8MB.

   *  `character_set_client'

     *Variable Name*      `character_set_client'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     The character set for statements that arrive from the client. The
     session value of this variable is set using the character set
     requested by the client when the client connects to the server.
     (Many clients support a `--default-character-set' option to enable
     this character set to be specified explicitly. See also *Note
     charset-connection::.) The global value of the variable is used to
     set the session value in cases when the client-requested value is
     unknown or not available, or the server is configured to ignore
     client requests:

        * The client is from a version of MySQL older than MySQL 4.1,
          and thus does not request a character set.

        * The client requests a character set not known to the server.
          For example, a Japanese-enabled client requests `sjis' when
          connecting to a server not configured with `sjis' support.

        * `mysqld' was started with the
          `--skip-character-set-client-handshake' option, which causes
          it to ignore client character set configuration. This
          reproduces MySQL 4.0 behavior and is useful should you wish
          to upgrade the server without upgrading all the clients.

   *  `character_set_connection'

     *Variable Name*      `character_set_connection'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     The character set used for literals that do not have a character
     set introducer and for number-to-string conversion.

   *  `character_set_database'

     *Variable Name*      `character_set_database'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     The character set used by the default database. The server sets
     this variable whenever the default database changes. If there is
     no default database, the variable has the same value as
     `character_set_server'.

   *  `character_set_filesystem'

     *Version Introduced* 5.1.6
     *Option Sets         Yes, `character_set_filesystem'
     Variable*            
     *Variable Name*      `character_set_filesystem'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     The filesystem character set. This variable is used to interpret
     string literals that refer to filenames, such as in the `LOAD DATA
     INFILE' and `SELECT ... INTO OUTFILE' statements and the
     `LOAD_FILE()' function.  Such filenames are converted from
     `character_set_client' to `character_set_filesystem' before the
     file opening attempt occurs. The default value is `binary', which
     means that no conversion occurs. For systems on which multi-byte
     filenames are allowed, a different value may be more appropriate.
     For example, if the system represents filenames using UTF-8, set
     `character_set_filesystem' to `'utf8''. This variable was added in
     MySQL 5.1.6.

   *  `character_set_results'

     *Variable Name*      `character_set_results'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     The character set used for returning query results to the client.

   *  `character_set_server'

     *Option Sets         Yes, `character_set_server'
     Variable*            
     *Variable Name*      `character_set_server'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     The server's default character set.

   *  `character_set_system'

     *Variable Name*      `character_set_system'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typestring           

     The character set used by the server for storing identifiers. The
     value is always `utf8'.

   *  `character_sets_dir'

     *Option Sets         Yes, `character_sets_dir'
     Variable*            
     *Variable Name*      `character-sets-dir'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The directory where character sets are installed.

   *  `collation_connection'

     *Variable Name*      `collation_connection'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     The collation of the connection character set.

   *  `collation_database'

     *Variable Name*      `collation_database'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     The collation used by the default database. The server sets this
     variable whenever the default database changes. If there is no
     default database, the variable has the same value as
     `collation_server'.

   *  `collation_server'

     *Option Sets         Yes, `collation_server'
     Variable*            
     *Variable Name*      `collation_server'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     The server's default collation.

   *  `completion_type'

     *Option Sets         Yes, `completion_type'
     Variable*            
     *Variable Name*      `competion_type'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default0 Valid       
     Values0, 1, 2        

     The transaction completion type:

        * If the value is 0 (the default), `COMMIT' and `ROLLBACK' are
          unaffected.

        * If the value is 1, `COMMIT' and `ROLLBACK' are equivalent to
          `COMMIT AND CHAIN' and `ROLLBACK AND CHAIN', respectively. (A
          new transaction starts immediately with the same isolation
          level as the just-terminated transaction.)

        * If the value is 2, `COMMIT' and `ROLLBACK' are equivalent to
          `COMMIT RELEASE' and `ROLLBACK RELEASE', respectively. (The
          server disconnects after terminating the transaction.)

   *  `concurrent_insert'

     *Option Sets         Yes, `concurrent_insert'
     Variable*            
     *Variable Name*      `concurrent_insert'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default1 Valid       
     Values0, 1, 2        

     If 1 (the default), MySQL allows `INSERT' and `SELECT' statements
     to run concurrently for `MyISAM' tables that have no free blocks
     in the middle of the data file. You can turn this option off by
     starting `mysqld' with `--safe' or `--skip-new'.

     This variable can take three integer values:

     *Value* *Description*
     0       Off
     1       (Default) Enables concurrent insert for `MyISAM'
             tables that don't have holes
     2       Enables concurrent inserts for all `MyISAM'
             tables, even those that have holes. For a table
             with a hole, new rows are inserted at the end of
             the table if it is in use by another thread.
             Otherwise, MySQL acquires a normal write lock and
             inserts the row into the hole.

     See also *Note concurrent-inserts::.

   *  `connect_timeout'

     *Option Sets         Yes, `connect_timeout'
     Variable*            
     *Variable Name*      `connect_timeout'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set (<=       
     5.1.23)*             
     Typenumeric Default5 
     *Value Set (>=       
     5.1.23)*             
     Typenumeric          
     Default10            

     The number of seconds that the `mysqld' server waits for a connect
     packet before responding with `Bad handshake'. The default value
     is 10 seconds as of MySQL 5.1.23 and 5 seconds before that.

     Increasing the `connect_timeout' value might help if clients
     frequently encounter errors of the form `Lost connection to MySQL
     server at 'XXX', system error: ERRNO'.

   * `datadir'

     *Option Sets         Yes, `datadir'
     Variable*            
     *Variable Name*      `datadir'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The MySQL data directory. This variable can be set with the
     `--datadir' option.

   *  `date_format'

     This variable is unused.

   *  `datetime_format'

     This variable is unused.

   * `debug'

     *Variable Name*      `debug'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           
     Default'd:t:o,/tmp/mysqld.trace

     This variable indicates the current debugging settings. It is
     available only for servers built with debugging support.  The
     initial value comes from the value of instances of the `--debug'
     option given at server startup. The global and session values may
     be set at runtime; the `SUPER' privilege is required, even for the
     session value.

     Assigning a value that begins with `+' or `-' cause the value to
     added to or subtracted from the current value:

          mysql> SET debug = 'T';
          mysql> SELECT @@debug;
          +---------+
          | @@debug |
          +---------+
          | T       |
          +---------+

          mysql> SET debug = '+P';
          mysql> SELECT @@debug;
          +---------+
          | @@debug |
          +---------+
          | P:T     |
          +---------+

          mysql> SET debug = '-P';
          mysql> SELECT @@debug;
          +---------+
          | @@debug |
          +---------+
          | T       |
          +---------+

     This variable was added in MySQL 5.1.7.

   *  `default_week_format'

     *Option Sets         Yes, `default_week_format'
     Variable*            
     *Variable Name*      `default_week_format'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default0 Range0-7    

     The default mode value to use for the `WEEK()' function. See *Note
     date-and-time-functions::.

   *  `delay_key_write'

     *Option Sets         Yes, `delay_key_write'
     Variable*            
     *Variable Name*      `delay-key-write'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     DefaultON Valid      
     ValuesON, OFF, ALL   

     This option applies only to `MyISAM' tables. It can have one of
     the following values to affect handling of the `DELAY_KEY_WRITE'
     table option that can be used in `CREATE TABLE' statements.

     *Option**Description*
     `OFF'   `DELAY_KEY_WRITE' is ignored.
     `ON'    MySQL honors any `DELAY_KEY_WRITE' option
             specified in `CREATE TABLE' statements. This is
             the default value.
     `ALL'   All new opened tables are treated as if they were
             created with the `DELAY_KEY_WRITE' option enabled.

     If `DELAY_KEY_WRITE' is enabled for a table, the key buffer is not
     flushed for the table on every index update, but only when the
     table is closed. This speeds up writes on keys a lot, but if you
     use this feature, you should add automatic checking of all
     `MyISAM' tables by starting the server with the `--myisam-recover'
     option (for example, `--myisam-recover=BACKUP,FORCE'). See *Note
     server-options::, and *Note myisam-start::.

     Note that if you enable external locking with
     `--external-locking', there is no protection against index
     corruption for tables that use delayed key writes.

   *  `delayed_insert_limit'

     *Option Sets         Yes, `delayed_insert_limit'
     Variable*            
     *Variable Name*      `delayed_insert_limit'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default100           
     Range1-4294967295    

     After inserting `delayed_insert_limit' delayed rows, the `INSERT
     DELAYED' handler thread checks whether there are any `SELECT'
     statements pending. If so, it allows them to execute before
     continuing to insert delayed rows.

   *  `delayed_insert_timeout'

     *Option Sets         Yes, `delayed_insert_timeout'
     Variable*            
     *Variable Name*      `delayed_insert_timeout'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default300           

     How many seconds an `INSERT DELAYED' handler thread should wait
     for `INSERT' statements before terminating.

   *  `delayed_queue_size'

     *Option Sets         Yes, `delayed_queue_size'
     Variable*            
     *Variable Name*      `delayed_queue_size'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default1000          
     Range1-4294967295    

     This is a per-table limit on the number of rows to queue when
     handling `INSERT DELAYED' statements.  If the queue becomes full,
     any client that issues an `INSERT DELAYED' statement waits until
     there is room in the queue again.

   *  `div_precision_increment'

     *Option Sets         Yes, `div_precision_increment'
     Variable*            
     *Variable Name*      `div_precision_increment'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default4 Range0-30   

     This variable indicates the number of digits by which to increase
     the scale of the result of division operations performed with the
     `/' operator. The default value is 4. The minimum and maximum
     values are 0 and 30, respectively. The following example
     illustrates the effect of increasing the default value.

          mysql> SELECT 1/7;
          +--------+
          | 1/7    |
          +--------+
          | 0.1429 |
          +--------+
          mysql> SET div_precision_increment = 12;
          mysql> SELECT 1/7;
          +----------------+
          | 1/7            |
          +----------------+
          | 0.142857142857 |
          +----------------+

   *  `event_scheduler'

     *Version Introduced* 5.1.6
     *Option Sets         Yes, `event-scheduler'
     Variable*            
     *Variable Name*      `event_scheduler'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     DefaultOFF Valid     
     ValuesON, OFF,       
     DISABLED             

     This variable indicates the status of the Event Scheduler; as of
     MySQL 5.1.12, possible values are `ON', `OFF', and `DISABLED',
     with the default being `OFF'. This variable and its effects on the
     Event Scheduler's operation are discussed in greater detail in the
     Overview section of the Events chapter.

     This variable was added in MySQL 5.1.6.

   *  `expire_logs_days'

     *Option Sets         Yes, `expire_logs_days'
     Variable*            
     *Variable Name*      `expire_logs_days'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default0 Range0-99   

     The number of days for automatic binary log removal. The default
     is 0, which means `no automatic removal.' Possible removals happen
     at startup and at binary log rotation.

   * `flush'

     *Variable Name*      `flush'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultOFF           

     If `ON', the server flushes (synchronizes) all changes to disk
     after each SQL statement. Normally, MySQL does a write of all
     changes to disk only after each SQL statement and lets the
     operating system handle the synchronizing to disk. See *Note
     crashing::. This variable is set to `ON' if you start `mysqld'
     with the `--flush' option.

   *  `flush_time'

     *Option Sets         Yes, `flush_time'
     Variable*            
     *Variable Name*      `flush_time'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typelinuxnumeric     
     Default0 Min Value0  
     *Value Set *         
     Typemacosxnumeric    
     Default0 Min Value0  
     *Value Set *         
     Typehpuxnumeric      
     Default0 Min Value0  
     *Value Set *         
     Typesolarisnumeric   
     Default0 Min Value0  
     *Value Set *         
     Typenetwarenumeric   
     Default0 Min Value0  
     *Value Set *         
     Typewindowsnumeric   
     Default1800 Min      
     Value0               

     If this is set to a non-zero value, all tables are closed every
     `flush_time' seconds to free up resources and synchronize
     unflushed data to disk. We recommend that this option be used only
     on Windows 9x or Me, or on systems with minimal resources.

   *  `ft_boolean_syntax'

     *Variable Name*      `ft_boolean_syntax'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           
     Default+-><()~*:""&  

     The list of operators supported by boolean full-text searches
     performed using `IN BOOLEAN MODE'.  See *Note fulltext-boolean::.

     The default variable value is `'+ -><()~*:""&|''. The rules for
     changing the value are as follows:

        * Operator function is determined by position within the string.

        * The replacement value must be 14 characters.

        * Each character must be an ASCII non-alphanumeric character.

        * Either the first or second character must be a space.

        * No duplicates are allowed except the phrase quoting operators
          in positions 11 and 12. These two characters are not required
          to be the same, but they are the only two that may be.

        * Positions 10, 13, and 14 (which by default are set to ``:'',
          ``&'', and ``|'') are reserved for future extensions.

   *  `ft_max_word_len'

     *Option Sets         Yes, `ft_max_word_len'
     Variable*            
     *Variable Name*      `ft_max_word_len'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric Min      
     Value10              

     The maximum length of the word to be included in a `FULLTEXT'
     index.

     *Note*:

     `FULLTEXT' indexes must be rebuilt after changing this variable.
     Use `REPAIR TABLE TBL_NAME QUICK'.

   *  `ft_min_word_len'

     *Option Sets         Yes, `ft_min_word_len'
     Variable*            
     *Variable Name*      `ft_min_word_len'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          
     Default4 Min Value1  

     The minimum length of the word to be included in a `FULLTEXT'
     index.

     *Note*:

     `FULLTEXT' indexes must be rebuilt after changing this variable.
     Use `REPAIR TABLE TBL_NAME QUICK'.

   *  `ft_query_expansion_limit'

     *Option Sets         Yes, `ft_query_expansion_limit'
     Variable*            
     *Variable Name*      `ft_query_expansion_limit'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          
     Default20            
     Range0-1000          

     The number of top matches to use for full-text searches performed
     using `WITH QUERY EXPANSION'.

   *  `ft_stopword_file'

     *Option Sets         Yes, `ft_stopword_file'
     Variable*            
     *Variable Name*      `ft_stopword_file'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The file from which to read the list of stopwords for full-text
     searches. All the words from the file are used; comments are _not_
     honored. By default, a built-in list of stopwords is used (as
     defined in the `storage/myisam/ft_static.c' file).  Setting this
     variable to the empty string (`''') disables stopword filtering.

     *Note*:

     `FULLTEXT' indexes must be rebuilt after changing this variable or
     the contents of the stopword file. Use `REPAIR TABLE TBL_NAME
     QUICK'.

   *  `general_log'

     *Version Introduced* 5.1.12
     *Option Sets         Yes, `general_log'
     Variable*            
     *Variable Name*      `general_log'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultOFF           

     Whether the general query log is enabled. The value can be 0 (or
     `OFF') to disable the log or 1 (or `ON') to enable the log. The
     default value depends on whether the `--log' option is given. The
     destination for log output is controlled by the `log_output'
     system variable; if that value is `NONE', no log entries are
     written even if the log is enabled. The `general_log' variable was
     added in MySQL 5.1.12.

   *  `general_log_file'

     *Version Introduced* 5.1.12
     *Variable Name*      `general_log_file'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typefilename         
     Defaulthost_name.log 

     The name of the general query log file. The default value is
     `HOST_NAME.log', but the initial value can be changed with the
     `--log' option. This variable was added in MySQL 5.1.12.

   *  `group_concat_max_len'

     *Option Sets         Yes, `group_concat_max_len'
     Variable*            
     *Variable Name*      `group_concat_max_len'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default1024 Min      
     Value4               

     The maximum allowed result length in bytes for the
     `GROUP_CONCAT()' function. The default is 1024.

   *  `have_archive'

     `YES' if `mysqld' supports `ARCHIVE' tables, `NO' if not. This
     variable was removed in MySQL 5.1.14.

   *  `have_blackhole_engine'

     `YES' if `mysqld' supports `BLACKHOLE' tables, `NO' if not. This
     variable was removed in MySQL 5.1.14.

   *  `have_compress'

     `YES' if the `zlib' compression library is available to the server,
     `NO' if not. If not, the `COMPRESS()' and `UNCOMPRESS()' functions
     cannot be used.

   *  `have_crypt'

     `YES' if the `crypt()' system call is available to the server,
     `NO' if not. If not, the `ENCRYPT()' function cannot be used.

   *  `have_csv'

     `YES' if `mysqld' supports `ARCHIVE' tables, `NO' if not.

   *  `have_dynamic_loading'

     `YES' if `mysqld' supports dynamic loading of plugins, `NO' if not.
     This variable was added in MySQL 5.1.10.

   *  `have_example_engine'

     `YES' if `mysqld' supports `EXAMPLE' tables, `NO' if not. This
     variable was removed in MySQL 5.1.14.

   *  `have_federated_engine'

     `YES' if `mysqld' supports `FEDERATED' tables, `NO' if not. This
     variable was removed in MySQL 5.1.14.

   *  `have_geometry'

     `YES' if the server supports spatial data types, `NO' if not.

   *  `have_innodb'

     `YES' if `mysqld' supports `InnoDB' tables.  `DISABLED' if
     `--skip-innodb' is used.

   *  `have_isam'

     In MySQL 5.1, this variable appears only for reasons of backward
     compatibility. It is always `NO' because `ISAM' tables are no
     longer supported. This variable was removed in MySQL 5.1.7.

   *  `have_merge_engine'

     `YES' if `mysqld' supports `MERGE' tables. `DISABLED' if
     `--skip-merge' is used. This variable was removed in MySQL 5.1.3.

   *  `have_openssl'

     `YES' if `mysqld' supports SSL connections, `NO' if not. As of
     MySQL 5.1.17, this variable is an alias for `have_ssl'.

   *  `have_partitioning'

     `YES' if `mysqld' supports partitioning. Added in MySQL 5.1.1 as
     `have_partition_engine' and renamed to `have_partioning' in 5.1.6.

   *  `have_query_cache'

     `YES' if `mysqld' supports the query cache, `NO' if not.

   *  `have_row_based_replication'

     *Version Introduced* 5.1.5
     *Variable Name*      `have_row_based_replication'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Deprecated*         5.1.15
     *Value Set *         
     Typeboolean          

     `YES' if the server can perform replication using row-based binary
     logging. If the value is `NO', the server can use only
     statement-based logging. See *Note replication-formats::. This
     variable was added in MySQL 5.1.5 and removed in 5.1.15.

   *  `have_raid'

     In MySQL 5.1, this variable appears only for reasons of backward
     compatibility. It is always `NO' because `RAID' tables are no
     longer supported. This variable was removed in MySQL 5.1.7.

   *  `have_rtree_keys'

     `YES' if `RTREE' indexes are available, `NO' if not. (These are
     used for spatial indexes in `MyISAM' tables.)

   *  `have_ssl'

     `YES' if `mysqld' supports SSL connections, `NO' if not. This
     variable was added in MySQL 5.1.17. Before that, use
     `have_openssl'.

   *  `have_symlink'

     `YES' if symbolic link support is enabled, `NO' if not. This is
     required on Unix for support of the `DATA DIRECTORY' and `INDEX
     DIRECTORY' table options, and on Windows for support of data
     directory symlinks.

   *  `hostname'

     *Version Introduced* 5.1.17
     *Variable Name*      `hostname'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typestring           

     The server sets this variable to the server hostname at startup.
     This variable was added in MySQL 5.1.17.

   *  `init_connect'

     *Option Sets         Yes, `init_connect'
     Variable*            
     *Variable Name*      `init_connect'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     A string to be executed by the server for each client that
     connects. The string consists of one or more SQL statements.  To
     specify multiple statements, separate them by semicolon
     characters. For example, each client begins by default with
     autocommit mode enabled. There is no global system variable to
     specify that autocommit should be disabled by default, but
     `init_connect' can be used to achieve the same effect:

          SET GLOBAL init_connect='SET AUTOCOMMIT=0';

     This variable can also be set on the command line or in an option
     file. To set the variable as just shown using an option file,
     include these lines:

          [mysqld]
          init_connect='SET AUTOCOMMIT=0'

     Note that the content of `init_connect' is not executed for users
     that have the `SUPER' privilege. This is done so that an erroneous
     value for `init_connect' does not prevent all clients from
     connecting. For example, the value might contain a statement that
     has a syntax error, thus causing client connections to fail. Not
     executing `init_connect' for users that have the `SUPER' privilege
     enables them to open a connection and fix the `init_connect' value.

   *  `init_file'

     *Option Sets         Yes, `init_file'
     Variable*            
     *Variable Name*      `init_file'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The name of the file specified with the `--init-file' option when
     you start the server. This should be a file containing SQL
     statements that you want the server to execute when it starts. Each
     statement must be on a single line and should not include comments.

     Note that the `--init-file' option is unavailable if MySQL was
     configured with the `--disable-grant-options' option. See *Note
     configure-options::.

   *  `init_slave'

     *Option Sets         Yes, `init_slave'
     Variable*            
     *Variable Name*      `init_slave'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     This variable is similar to `init_connect', but is a string to be
     executed by a slave server each time the SQL thread starts. The
     format of the string is the same as for the `init_connect'
     variable.

     *Note*:

     The SQL thread sends an acknowledgement to the client before
     `init_slave' is executed.  Therefore, it is not guaranteed that
     `init_slave' has been executed when `START SLAVE' returns. See
     *Note start-slave::, for more information.

   * `innodb_XXX'

     `InnoDB' system variables are listed in *Note innodb-parameters::.

   *  `interactive_timeout'

     *Option Sets         Yes, `interactive_timeout'
     Variable*            
     *Variable Name*      `interactive_timeout'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default28800 Min     
     Value1               

     The number of seconds the server waits for activity on an
     interactive connection before closing it. An interactive client is
     defined as a client that uses the `CLIENT_INTERACTIVE' option to
     *Note `mysql_real_connect()': mysql-real-connect. See also
     `wait_timeout'.

   *  `join_buffer_size'

     *Option Sets         Yes, `join_buffer_size'
     Variable*            
     *Variable Name*      `join_buffer_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default131072        
     Range8200-4294967295 

     The size of the buffer that is used for joins that do not use
     indexes and thus perform full table scans. Normally, the best way
     to get fast joins is to add indexes. Increase the value of
     `join_buffer_size' to get a faster full join when adding indexes
     is not possible. One join buffer is allocated for each full join
     between two tables.  For a complex join between several tables for
     which indexes are not used, multiple join buffers might be
     necessary.

     The maximum allowable setting for `join_buffer_size' is 4GB. As of
     MySQL 5.1.23, values larger than 4GB are allowed for 64-bit
     platforms (except 64-bit Windows, for which large values are
     truncated to 4GB with a warning).

   *  `keep_files_on_create'

     *Version Introduced* 5.1.21
     *Option Sets         Yes, `keep_files_on_create'
     Variable*            
     *Variable Name*      `keep_files_on_create'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultOFF           

     If a `MyISAM' table is created with no `DATA DIRECTORY' option, the
     `.MYD' file is created in the database directory. By default, if
     `MyISAM' finds an existing `.MYD' file in this case, it overwrites
     it. The same applies to `.MYI' files for tables created with no
     `INDEX DIRECTORY' option. To suppress this behavior, set the
     `keep_files_on_create' variable to `ON' (1), in which case
     `MyISAM' will not overwrite existing files and returns an error
     instead. The default value is `OFF' (0).

     If a `MyISAM' table is created with a `DATA DIRECTORY' or `INDEX
     DIRECTORY' option and an existing `.MYD' or `.MYI' file is found,
     MyISAM always returns an error. It will not overwrite a file in
     the specified directory.

     This variable was added in MySQL 5.1.23.

   *  `key_buffer_size'

     *Option Sets         Yes, `key_buffer_size'
     Variable*            
     *Variable Name*      `key_buffer_size'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default8388608       
     Range8-4294967295    

     Index blocks for `MyISAM' tables are buffered and are shared by
     all threads.  `key_buffer_size' is the size of the buffer used for
     index blocks. The key buffer is also known as the key cache.

     The maximum allowable setting for `key_buffer_size' is 4GB on
     32-bit platforms. As of MySQL 5.1.23, values larger than 4GB are
     allowed for 64-bit platforms. The effective maximum size might be
     less, depending on your available physical RAM and per-process RAM
     limits imposed by your operating system or hardware platform. The
     value of this variable indicates the amount of memory requested.
     Internally, the server allocates as much memory as possible up to
     this amount, but the actual allocation might be less.

     Increase the value to get better index handling (for all reads and
     multiple writes) to as much as you can afford.  Using a value that
     is 25% of total memory on a machine that mainly runs MySQL is
     quite common. However, if you make the value too large (for
     example, more than 50% of your total memory) your system might
     start to page and become extremely slow. MySQL relies on the
     operating system to perform filesystem caching for data reads, so
     you must leave some room for the filesystem cache. Consider also
     the memory requirements of other storage engines.

     For even more speed when writing many rows at the same time, use
     `LOCK TABLES'. See *Note insert-speed::.

     You can check the performance of the key buffer by issuing a `SHOW
     STATUS' statement and examining the `Key_read_requests',
     `Key_reads', `Key_write_requests', and `Key_writes' status
     variables. (See *Note show::.) The `Key_reads/Key_read_requests'
     ratio should normally be less than 0.01. The
     `Key_writes/Key_write_requests' ratio is usually near 1 if you are
     using mostly updates and deletes, but might be much smaller if you
     tend to do updates that affect many rows at the same time or if
     you are using the `DELAY_KEY_WRITE' table option.

     The fraction of the key buffer in use can be determined using
     `key_buffer_size' in conjunction with the `Key_blocks_unused'
     status variable and the buffer block size, which is available from
     the `key_cache_block_size' system variable:

          1 - ((Key_blocks_unused x key_cache_block_size) / key_buffer_size)

     This value is an approximation because some space in the key
     buffer may be allocated internally for administrative structures.

     It is possible to create multiple `MyISAM' key caches. The size
     limit of 4GB applies to each cache individually, not as a group.
     See *Note myisam-key-cache::.

   *  `key_cache_age_threshold'

     *Option Sets         Yes, `key_cache_age_threshold'
     Variable*            
     *Variable Name*      `key_cache_age_threshold'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default300           
     Range100-4294967295  

     This value controls the demotion of buffers from the hot sub-chain
     of a key cache to the warm sub-chain. Lower values cause demotion
     to happen more quickly. The minimum value is 100. The default
     value is 300. See *Note myisam-key-cache::.

   *  `key_cache_block_size'

     *Option Sets         Yes, `key_cache_block_size'
     Variable*            
     *Variable Name*      `key_cache_block_size'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default1024          
     Range512-16384       

     The size in bytes of blocks in the key cache. The default value is
     1024. See *Note myisam-key-cache::.

   *  `key_cache_division_limit'

     *Option Sets         Yes, `key_cache_division_limit'
     Variable*            
     *Variable Name*      `key_cache_division_limit'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default100           
     Range1-100           

     The division point between the hot and warm sub-chains of the key
     cache buffer chain. The value is the percentage of the buffer
     chain to use for the warm sub-chain. Allowable values range from 1
     to 100. The default value is 100. See *Note myisam-key-cache::.

   * `language'

     *Option Sets         Yes, `language'
     Variable*            
     *Variable Name*      `language'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         
     Default/usr/local/mysql/share/mysql/english/

     The language used for error messages.

   *  `large_files_support'

     *Variable Name*      `large_files_support'
     *Variable Scope*     Global
     *Dynamic Variable*   No

     Whether `mysqld' was compiled with options for large file support.

   *  `large_pages'

     *Option Sets         Yes, `large_pages'
     Variable*            
     *Variable Name*      `large_pages'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Platform Specific*  linux
     *Value Set *         
     Typelinuxboolean     
     DefaultFALSE         

     Whether large page support is enabled.

     For more information, see the entry for the `--large-pages' server
     option.

   *  `large_page_size'

     *Variable Name*      `large_page_size'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typelinuxnumeric     
     Default0             

     If large page support is enabled, this shows the size of memory
     pages. Currently, large memory pages are supported only on Linux;
     on other platforms, the value of this variable is always 0.

     For more information, see the entry for the `--large-pages' server
     option.

   *  `lc_time_names'

     *Version Introduced* 5.1.12
     *Variable Name*      `lc_time_names'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     This variable specifies the locale that controls the language used
     to display day and month names and abbreviations. This variable
     affects the output from the `DATE_FORMAT()', `DAYNAME()' and
     `MONTHNAME()' functions.  Locale names are POSIX-style values such
     as `'ja_JP'' or `'pt_BR''.  The default value is `'en_US''
     regardless of your system's locale setting. For further
     information, see *Note locale-support::. This variable was added
     in MySQL 5.1.12.

   *  `license'

     *Variable Name*      `license'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typestring           
     DefaultGPL           

     The type of license the server has.

   *  `local_infile'

     *Variable Name*      `local_infile'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes

     Whether `LOCAL' is supported for `LOAD DATA INFILE' statements. See
     *Note load-data-local::.

   *  `locked_in_memory'

     *Variable Name*      `locked_in_memory'
     *Variable Scope*     Global
     *Dynamic Variable*   No

     Whether `mysqld' was locked in memory with `--memlock'.

   *  `log'

     Whether logging of all statements to the general query log is
     enabled. See *Note query-log::.

   *  `log_bin'

     *Variable Name*      `log_bin'
     *Variable Scope*     Global
     *Dynamic Variable*   No

     Whether the binary log is enabled. See *Note binary-log::.

   *  `log_bin_trust_function_creators'

     *Option Sets         Yes, `log_bin_trust_function_creators'
     Variable*            
     *Variable Name*      `log_bin_trust_function_creators'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     This variable applies when binary logging is enabled. It controls
     whether stored function creators can be trusted not to create
     stored functions that will cause unsafe events to be written to
     the binary log. If set to 0 (the default), users are not allowed
     to create or alter stored functions unless they have the `SUPER'
     privilege in addition to the `CREATE ROUTINE' or `ALTER ROUTINE'
     privilege. A setting of 0 also enforces the restriction that a
     function must be declared with the `DETERMINISTIC' characteristic,
     or with the `READS SQL DATA' or `NO SQL' characteristic.  If the
     variable is set to 1, MySQL does not enforce these restrictions on
     stored function creation. This variable also applies to trigger
     creation. See *Note stored-procedure-logging::.

   *  `log_error'

     *Option Sets         Yes, `log_error'
     Variable*            
     *Variable Name*      `log_error'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The location of the error log.

   *  `log_output'

     *Version Introduced* 5.1.6
     *Option Sets         Yes, `log_output'
     Variable*            
     *Variable Name*      `log_output'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     DefaultFILE Valid    
     ValuesTABLE, FILE,   
     NONE                 

     The destination for general query log and slow query log output.
     The value can be a comma-separated list of one or more of the
     words `TABLE' (log to tables), `FILE' (log to files), or `NONE'
     (do not log to tables or files). The default value is `TABLE'.
     `NONE', if present, takes precedence over any other specifiers. If
     the value is `NONE' log entries are not written even if the logs
     are enabled. If the logs are not enabled, no logging occurs even
     if the value of `log_output' is not `NONE'. For more information,
     see *Note log-tables::. This variable was added in MySQL 5.1.6.

   *  `log_queries_not_using_indexes'

     *Option Sets         Yes, `log_queries_not_using_indexes'
     Variable*            
     *Variable Name*      `log_queries_not_using_indexes'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          

     Whether queries that do not use indexes are logged to the slow
     query log. See *Note slow-query-log::. This variable was added in
     MySQL 5.1.11.

   *  `log_slave_updates'

     Whether updates received by a slave server from a master server
     should be logged to the slave's own binary log.  Binary logging
     must be enabled on the slave for this variable to have any effect.
     See *Note replication-options::.

   *  `log_slow_queries'

     *Option Sets         Yes, `log_slow_queries'
     Variable*            
     *Variable Name*      `log_slow_queries'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          

     Whether slow queries should be logged. `Slow' is determined by the
     value of the `long_query_time' variable. See *Note
     slow-query-log::.

   * `log_warnings'

     *Option Sets         Yes, `log-warnings'
     Variable*            
     *Variable Name*      `log_warnings'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Disabled by*        `skip-log-warnings'
     *Value Set *         
     Typenumeric Default1 

     Whether to produce additional warning messages. It is enabled (1)
     by default and can be disabled by setting it to 0. Aborted
     connections are not logged to the error log unless the value is
     greater than 1.

   *  `long_query_time'

     *Option Sets         Yes, `long_query_time'
     Variable*            
     *Variable Name*      `long_query_time'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set (>=       
     5.1.21)*             
     Typenumeric          
     Default10 Min Value0 

     If a query takes longer than this many seconds, the server
     increments the `Slow_queries' status variable. If you are using the
     `--log-slow-queries' option, the query is logged to the slow query
     log file. This value is measured in real time, not CPU time, so a
     query that is under the threshold on a lightly loaded system might
     be above the threshold on a heavily loaded one. Prior to MySQL
     5.1.21, the minimum value is 1, and the value for this variable
     must be an integer. Beginning with MySQL 5.1.21, the minimum is 0,
     and a resolution of microseconds is supported when logging to a
     file. However, the microseconds part is ignored and only integer
     values are written when logging to tables.  The default value is
     10. See *Note slow-query-log::.

   *  `low_priority_updates'

     *Option Sets         Yes, `low_priority_updates'
     Variable*            
     *Variable Name*      `low_priority_updates'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     If set to `1', all `INSERT', `UPDATE', `DELETE', and `LOCK TABLE
     WRITE' statements wait until there is no pending `SELECT' or `LOCK
     TABLE READ' on the affected table. This affects only storage
     engines that use only table-level locking (`MyISAM', `MEMORY',
     `MERGE'). This variable previously was named
     `sql_low_priority_updates'.

   *  `lower_case_file_system'

     *Option Sets         Yes, `lower_case_file_system'
     Variable*            
     *Variable Name*      `lower_case_file_system'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typeboolean          

     This variable describes the case sensitivity of filenames on the
     filesystem where the data directory is located.  `OFF' means
     filenames are case sensitive, `ON' means they are not case
     sensitive.

   *  `lower_case_table_names'

     *Option Sets         Yes, `lower_case_table_names'
     Variable*            
     *Variable Name*      `lower_case_table_names'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          
     Default0 Range0-2    

     If set to 1, table names are stored in lowercase on disk and table
     name comparisons are not case sensitive. If set to 2 table names
     are stored as given but compared in lowercase.  This option also
     applies to database names and table aliases. See *Note
     identifier-case-sensitivity::.

     If you are using `InnoDB' tables, you should set this variable to
     1 on all platforms to force names to be converted to lowercase.

     You should _not_ set this variable to 0 if you are running MySQL
     on a system that does not have case-sensitive filenames (such as
     Windows or Mac OS X). If this variable is not set at startup and
     the filesystem on which the data directory is located does not have
     case-sensitive filenames, MySQL automatically sets
     `lower_case_table_names' to 2.

   *  `max_allowed_packet'

     *Option Sets         Yes, `max_allowed_packet'
     Variable*            
     *Variable Name*      `max_allowed_packet'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default1048576       
     Range1024-1073741824 

     The maximum size of one packet or any generated/intermediate
     string.

     The packet message buffer is initialized to `net_buffer_length'
     bytes, but can grow up to `max_allowed_packet' bytes when needed.
     This value by default is small, to catch large (possibly
     incorrect) packets.

     You must increase this value if you are using large `BLOB' columns
     or long strings. It should be as big as the largest `BLOB' you
     want to use. The protocol limit for `max_allowed_packet' is 1GB.
     The value should be a multiple of 1024; non-multiples are rounded
     down to the nearest multiple.

   *  `max_binlog_cache_size'

     *Option Sets         Yes, `max_binlog_cache_size'
     Variable*            
     *Variable Name*      `max_binlog_cache_size'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default4294967295    
     Range4096-4294967295 

     If a multiple-statement transaction requires more than this many
     bytes of memory, the server generates a `Multi-statement
     transaction required more than 'max_binlog_cache_size' bytes of
     storage' error.  The minimum value is 4096, the maximum and
     default values are 4GB.

   *  `max_binlog_size'

     *Option Sets         Yes, `max_binlog_size'
     Variable*            
     *Variable Name*      `max_binlog_size'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default1073741824    
     Min Value4096        

     If a write to the binary log causes the current log file size to
     exceed the value of this variable, the server rotates the binary
     logs (closes the current file and opens the next one). You cannot
     set this variable to more than 1GB or to less than 4096 bytes. The
     default value is 1GB.

     A transaction is written in one chunk to the binary log, so it is
     never split between several binary logs. Therefore, if you have
     big transactions, you might see binary logs larger than
     `max_binlog_size'.

     If `max_relay_log_size' is 0, the value of `max_binlog_size'
     applies to relay logs as well.

   *  `max_connect_errors'

     *Option Sets         Yes, `max_connect_errors'
     Variable*            
     *Variable Name*      `max_connect_errors'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default10            
     Range1-4294967295    

     If there are more than this number of interrupted connections from
     a host, that host is blocked from further connections. You can
     unblock blocked hosts with the `FLUSH HOSTS' statement.

   *  `max_connections'

     *Option Sets         Yes, `max_connections'
     Variable*            
     *Variable Name*      `max_connections'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set (<=       
     5.1.14)*             
     Typenumeric          
     Default100           
     *Value Set (>=       
     5.1.15)*             
     Typenumeric          
     Default151           
     Range1-16384         
     *Value Set (>=       
     5.1.17)*             
     Typenumeric          
     Default151           
     Range1-100000        

     The number of simultaneous client connections allowed. By default,
     this is 151, beginning with MySQL 5.1.15.  (Previously, the
     default was 100.) See *Note too-many-connections::, for more
     information.

     MySQL Enterprise

     For notification that the maximum number of connections is getting
     dangerously high and for advice on setting the optimum value for
     `max_connections' subscribe to the MySQL Enterprise Monitor. For
     more information see
     `http://www.mysql.com/products/enterprise/advisors.html'.

     Increasing this value increases the number of file descriptors
     that `mysqld' requires. See *Note table-cache::, for comments on
     file descriptor limits.

   *  `max_delayed_threads'

     *Option Sets         Yes, `max_delayed_threads'
     Variable*            
     *Variable Name*      `max_delayed_threads'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default20            
     Range0-16384         

     Do not start more than this number of threads to handle `INSERT
     DELAYED' statements. If you try to insert data into a new table
     after all `INSERT DELAYED' threads are in use, the row is inserted
     as if the `DELAYED' attribute wasn't specified. If you set this to
     0, MySQL never creates a thread to handle `DELAYED' rows; in
     effect, this disables `DELAYED' entirely.

     For the `SESSION' value of this variable, the only valid values
     are 0 or the `GLOBAL' value.

   *  `max_error_count'

     *Option Sets         Yes, `max_error_count'
     Variable*            
     *Variable Name*      `max_error_count'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default64            
     Range0-65535         

     The maximum number of error, warning, and note messages to be
     stored for display by the `SHOW ERRORS' and `SHOW WARNINGS'
     statements.

   *  `max_heap_table_size'

     *Option Sets         Yes, `max_heap_table_size'
     Variable*            
     *Variable Name*      `max_heap_table_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default16777216      
     Range16384-4294967295

     This variable sets the maximum size to which `MEMORY' tables are
     allowed to grow. The value of the variable is used to calculate
     `MEMORY' table `MAX_ROWS' values. Setting this variable has no
     effect on any existing `MEMORY' table, unless the table is
     re-created with a statement such as `CREATE TABLE' or altered with
     `ALTER TABLE' or `TRUNCATE TABLE'. A server restart also sets the
     maximum size of existing `MEMORY' tables to the global
     `max_heap_table_size' value.

     MySQL Enterprise

     Subscribers to the MySQL Enterprise Monitor receive
     recommendations for the optimum setting for `max_heap_table_size'.
     For more information see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   *  `max_insert_delayed_threads'

     *Variable Name*      `max_insert_delayed_threads'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          

     This variable is a synonym for `max_delayed_threads'.

   *  `max_join_size'

     *Option Sets         Yes, `max_join_size'
     Variable*            
     *Variable Name*      `max_join_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default4294967295    
     Range1-4294967295    

     Do not allow `SELECT' statements that probably need to examine
     more than `max_join_size' rows (for single-table statements) or
     row combinations (for multiple-table statements) or that are
     likely to do more than `max_join_size' disk seeks. By setting this
     value, you can catch `SELECT' statements where keys are not used
     properly and that would probably take a long time. Set it if your
     users tend to perform joins that lack a `WHERE' clause, that take a
     long time, or that return millions of rows.

     Setting this variable to a value other than `DEFAULT' resets the
     value of `SQL_BIG_SELECTS' to `0'.  If you set the
     `SQL_BIG_SELECTS' value again, the `max_join_size' variable is
     ignored.

     If a query result is in the query cache, no result size check is
     performed, because the result has previously been computed and it
     does not burden the server to send it to the client.

     This variable previously was named `sql_max_join_size'.

   *  `max_length_for_sort_data'

     *Option Sets         Yes, `max_length_for_sort_data'
     Variable*            
     *Variable Name*      `max_length_for_sort_data'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default1024          
     Range4-8388608       

     The cutoff on the size of index values that determines which
     `filesort' algorithm to use. See *Note order-by-optimization::.

   *  `max_prepared_stmt_count'

     *Version Introduced* 5.1.10
     *Command Line        
     Format*              
     -max_prepared_stmt_count=#5.0.21
     *Config File Format* 
     max_prepared_stmt_count5.0.21
     *Option Sets         Yes, `max_prepared_stmt_count'
     Variable*            
     *Variable Name*      `max_prepared_stmt_count'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default16382         
     Range0-1048576       

     This variable limits the total number of prepared statements in
     the server. It can be used in environments where there is the
     potential for denial-of-service attacks based on running the
     server out of memory by preparing huge numbers of statements. The
     default value is 16,382. The allowable range of values is from 0
     to 1 million. If the value is set lower than the current number of
     prepared statements, existing statements are not affected and can
     be used, but no new statements can be prepared until the current
     number drops below the limit. This variable was added in MySQL
     5.1.10.

   *  `max_relay_log_size'

     *Option Sets         Yes, `max_relay_log_size'
     Variable*            
     *Variable Name*      `max_relay_log_size'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default0             
     Range0-1073741824    

     If a write by a replication slave to its relay log causes the
     current log file size to exceed the value of this variable, the
     slave rotates the relay logs (closes the current file and opens
     the next one). If `max_relay_log_size' is 0, the server uses
     `max_binlog_size' for both the binary log and the relay log. If
     `max_relay_log_size' is greater than 0, it constrains the size of
     the relay log, which enables you to have different sizes for the
     two logs.  You must set `max_relay_log_size' to between 4096 bytes
     and 1GB (inclusive), or to 0. The default value is 0. See *Note
     replication-implementation-details::.

   *  `max_seeks_for_key'

     *Option Sets         Yes, `max_seeks_for_key'
     Variable*            
     *Variable Name*      `max_seeks_for_key'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default4294967295    
     Range1-4294967295    

     Limit the assumed maximum number of seeks when looking up rows
     based on a key. The MySQL optimizer assumes that no more than this
     number of key seeks are required when searching for matching rows
     in a table by scanning an index, regardless of the actual
     cardinality of the index (see *Note show-index::). By setting this
     to a low value (say, 100), you can force MySQL to prefer indexes
     instead of table scans.

   *  `max_sort_length'

     *Option Sets         Yes, `max_sort_length'
     Variable*            
     *Variable Name*      `max_sort_length'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default1024          
     Range4-8388608       

     The number of bytes to use when sorting `BLOB' or `TEXT' values.
     Only the first `max_sort_length' bytes of each value are used; the
     rest are ignored.

   *  `max_sp_recursion_depth'

     *Option Sets         Yes, `max_sp_recursion_depth'
     Variable*            
     *Variable Name*      `max_sp_recursion_depth'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default0 Max         
     Value255             

     The number of times that any given stored procedure may be called
     recursively. The default value for this option is 0, which
     completely disallows recursion in stored procedures.  The maximum
     value is 255.

     Stored procedure recursion increases the demand on thread stack
     space. If you increase the value of `max_sp_recursion_depth', it
     may be necessary to increase thread stack size by increasing the
     value of `thread_stack' at server startup.

   *  `max_tmp_tables'

     *Option Sets         Yes, `max_tmp_tables'
     Variable*            
     *Variable Name*      `max_tmp_tables'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default32            
     Range1-4294967295    

     The maximum number of temporary tables a client can keep open at
     the same time. (This option does not yet do anything.)

   *  `max_user_connections'

     *Option Sets         Yes, `max_user_connections'
     Variable*            
     *Variable Name*      `max_user_connections'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Range1-4294967295    

     The maximum number of simultaneous connections allowed to any
     given MySQL account. A value of 0 means `no limit.'

     This variable has both a global scope and a (read-only) session
     scope. The session variable has the same value as the global
     variable unless the current account has a non-zero
     `MAX_USER_CONNECTIONS' resource limit. In that case, the session
     value reflects the account limit.

   *  `max_write_lock_count'

     *Option Sets         Yes, `max_write_lock_count'
     Variable*            
     *Variable Name*      `max_write_lock_count'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default4294967295    
     Range1-4294967295    

     After this many write locks, allow some pending read lock requests
     to be processed in between.

   *  `min_examined_row_limit'

     *Version Introduced* 5.1.21
     *Variable Name*      `min_examined_row_limit'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default0             
     Range0-4294967295    

     Queries that examine fewer than this number of rows are not logged
     to the slow query log. This variable was added in MySQL 5.1.21.

   *  `myisam_block_size'

     *Option Sets         Yes, `myisam_block_size'
     Variable*            
     *Variable Name*      `myisam_block_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default1024          
     Range1024-16384      

     The block size to be used for `MyISAM' index pages.

   *  `myisam_data_pointer_size'

     *Option Sets         Yes, `myisam_data_pointer_size'
     Variable*            
     *Variable Name*      `myisam_data_pointer_size'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default6 Range2-7    

     The default pointer size in bytes, to be used by `CREATE TABLE' for
     `MyISAM' tables when no `MAX_ROWS' option is specified. This
     variable cannot be less than 2 or larger than 7. The default value
     is 6. See *Note full-table::.

   *  `myisam_max_sort_file_size'

     *Option Sets         Yes, `myisam_max_sort_file_size'
     Variable*            
     *Variable Name*      `myisam_max_sort_file_size'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default2147483648    

     The maximum size of the temporary file that MySQL is allowed to
     use while re-creating a `MyISAM' index (during `REPAIR TABLE',
     `ALTER TABLE', or `LOAD DATA INFILE'). If the file size would be
     larger than this value, the index is created using the key cache
     instead, which is slower. The value is given in bytes.

     The default value is 2GB. If `MyISAM' index files exceed this size
     and disk space is available, increasing the value may help
     performance.

   *  `myisam_recover_options'

     *Variable Name*      `myisam_recover_options'
     *Variable Scope*     Global
     *Dynamic Variable*   No

     The value of the `--myisam-recover' option.  See *Note
     server-options::.

   *  `myisam_repair_threads'

     *Option Sets         Yes, `myisam_repair_threads'
     Variable*            
     *Variable Name*      `myisam_repair_threads'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default1             
     Range1-4294967295    

     If this value is greater than 1, `MyISAM' table indexes are
     created in parallel (each index in its own thread) during the
     `Repair by sorting' process. The default value is 1.

     *Note*:

     Multi-threaded repair is still _beta-quality_ code.

   *  `myisam_sort_buffer_size'

     *Option Sets         Yes, `myisam_sort_buffer_size'
     Variable*            
     *Variable Name*      `myisam_sort_buffer_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default8388608       
     Range4-4294967295    

     The size of the buffer that is allocated when sorting `MyISAM'
     indexes during a `REPAIR TABLE' or when creating indexes with
     `CREATE INDEX' or `ALTER TABLE'.

     The maximum allowable setting for `myisam_sort_buffer_size' is
     4GB. As of MySQL 5.1.23, values larger than 4GB are allowed for
     64-bit platforms (except 64-bit Windows, for which large values are
     truncated to 4GB with a warning).

   *  `myisam_stats_method'

     *Option Sets         Yes, `myisam_stats_method'
     Variable*            
     *Variable Name*      `myisam_stats_method'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     Valid                
     Valuesnulls_equal,   
     nulls_unequal        

     How the server treats `NULL' values when collecting statistics
     about the distribution of index values for `MyISAM' tables. This
     variable has two possible values, `nulls_equal' and
     `nulls_unequal'. For `nulls_equal', all `NULL' index values are
     considered equal and form a single value group that has a size
     equal to the number of `NULL' values. For `nulls_unequal', `NULL'
     values are considered unequal, and each `NULL' forms a distinct
     value group of size 1.

     The method that is used for generating table statistics influences
     how the optimizer chooses indexes for query execution, as
     described in *Note myisam-index-statistics::.

     Any unique prefix of a valid value may be used to set the value of
     this variable.

   *  `myisam_use_mmap'

     *Version Introduced* 5.1.4
     *Option Sets         Yes, `myisam_use_mmap'
     Variable*            
     *Variable Name*      `myisam_use_mmap'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Use memory mapping for reading and writing `MyISAM' tables. This
     variable was added in MySQL 5.1.4.

   *  `named_pipe'

     *Variable Name*      `named_pipe'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Platform Specific*  windows

     (Windows only.) Indicates whether the server supports connections
     over named pipes.

   *  `net_buffer_length'

     *Option Sets         Yes, `net_buffer_length'
     Variable*            
     *Variable Name*      `net_buffer_length'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default16384         
     Range1024-1048576    

     Each client thread is associated with a connection buffer and
     result buffer. Both begin with a size given by `net_buffer_length'
     but are dynamically enlarged up to `max_allowed_packet' bytes as
     needed. The result buffer shrinks to `net_buffer_length' after
     each SQL statement.

     This variable should not normally be changed, but if you have very
     little memory, you can set it to the expected length of statements
     sent by clients. If statements exceed this length, the connection
     buffer is automatically enlarged. The maximum value to which
     `net_buffer_length' can be set is 1MB.

   *  `net_read_timeout'

     *Option Sets         Yes, `net_read_timeout'
     Variable*            
     *Variable Name*      `net_read_timeout'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default30 Min Value1 

     The number of seconds to wait for more data from a connection
     before aborting the read. This timeout applies only to TCP/IP
     connections, not to connections made via Unix socket files, named
     pipes, or shared memory. When the server is reading from the
     client, `net_read_timeout' is the timeout value controlling when
     to abort. When the server is writing to the client,
     `net_write_timeout' is the timeout value controlling when to
     abort. See also `slave_net_timeout'.

   *  `net_retry_count'

     *Option Sets         Yes, `net_retry_count'
     Variable*            
     *Variable Name*      `net_retry_count'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default10            
     Range1-4294967295    

     If a read on a communication port is interrupted, retry this many
     times before giving up. This value should be set quite high on
     FreeBSD because internal interrupts are sent to all threads.

   *  `net_write_timeout'

     *Option Sets         Yes, `net_write_timeout'
     Variable*            
     *Variable Name*      `net_write_timeout'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default60 Min Value1 

     The number of seconds to wait for a block to be written to a
     connection before aborting the write. This timeout applies only to
     TCP/IP connections, not to connections made via Unix socket files,
     named pipes, or shared memory. See also `net_read_timeout'.

   *  `new'

     *Option Sets         Yes, `new'
     Variable*            
     *Variable Name*      `new'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Disabled by*        `skip-new'
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     This variable was used in MySQL 4.0 to turn on some 4.1 behaviors,
     and is retained for backward compatibility. In MySQL 5.1, its
     value is always `OFF'.

   *  `old'

     *Version Introduced* 5.1.18
     *Variable Name*      `old'
     *Variable Scope*     Global
     *Dynamic Variable*   No

     `old' is a compatibility variable. It is disabled by default, but
     can be enabled at startup to revert the server to behaviors
     present in older versions.

     Currently, when `old' is enabled, it changes the default scope of
     index hints to that used prior to MySQL 5.1.17. That is, index
     hints with no `FOR' clause apply only to how indexes are used for
     row retrieval and not to resolution of `ORDER BY' or `GROUP BY'
     clauses. (See *Note index-hints::.) Take care about enabling this
     in a replication setup. With statement-based binary logging,
     having different modes for the master and slaves might lead to
     replication errors.

     This variable was added as `old_mode' in MySQL 5.1.17 and renamed
     to `old' in MySQL 5.1.18.

   *  `old_passwords'

     *Option Sets         Yes, `old_passwords'
     Variable*            
     *Variable Name*      `old_passwords'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Whether the server should use pre-4.1-style passwords for MySQL
     user accounts. See *Note old-client::.

   *  `one_shot'

     This is not a variable, but it can be used when setting some
     variables. It is described in *Note set-option::.

   *  `open_files_limit'

     *Option Sets         Yes, `open_files_limit'
     Variable*            
     *Variable Name*      `open_files_limit'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          
     Default0             
     Range0-65535         

     The number of files that the operating system allows `mysqld' to
     open. This is the real value allowed by the system and might be
     different from the value you gave using the `--open-files-limit'
     option to `mysqld' or `mysqld_safe'. The value is 0 on systems
     where MySQL can't change the number of open files.

   *  `optimizer_prune_level'

     *Option Sets         Yes, `optimizer_prune_level'
     Variable*            
     *Variable Name*      `optimizer_prune_level'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean Default1 

     Controls the heuristics applied during query optimization to prune
     less-promising partial plans from the optimizer search space. A
     value of 0 disables heuristics so that the optimizer performs an
     exhaustive search. A value of 1 causes the optimizer to prune
     plans based on the number of rows retrieved by intermediate plans.

   *  `optimizer_search_depth'

     *Option Sets         Yes, `optimizer_search_depth'
     Variable*            
     *Variable Name*      `optimizer_search_depth'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default62            

     The maximum depth of search performed by the query optimizer.
     Values larger than the number of relations in a query result in
     better query plans, but take longer to generate an execution plan
     for a query. Values smaller than the number of relations in a
     query return an execution plan quicker, but the resulting plan may
     be far from being optimal. If set to 0, the system automatically
     picks a reasonable value. If set to the maximum number of tables
     used in a query plus 2, the optimizer switches to the algorithm
     used in MySQL 5.0.0 (and previous versions) for performing
     searches.

   *  `pid_file'

     *Option Sets         Yes, `pid_file'
     Variable*            
     *Variable Name*      `pid_file'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The pathname of the process ID (PID) file. This variable can be
     set with the `--pid-file' option.

   *  `plugin_dir'

     *Version Introduced* 5.1.2
     *Option Sets         Yes, `plugin_dir'
     Variable*            
     *Variable Name*      `plugin_dir'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         
     Default/usr/local/mysql/lib/mysql

     The pathname of the plugin directory. This variable was added in
     MySQL 5.1.2.

   * `port'

     *Option Sets         Yes, `port'
     Variable*            
     *Variable Name*      `port'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          
     Default3306          

     The number of the port on which the server listens for TCP/IP
     connections. This variable can be set with the `--port' option.

   *  `preload_buffer_size'

     *Option Sets         Yes, `preload_buffer_size'
     Variable*            
     *Variable Name*      `preload_buffer_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default32768         
     Range1024-1073741824 

     The size of the buffer that is allocated when preloading indexes.

   *  `prepared_stmt_count'

     The current number of prepared statements. (The maximum number of
     statements is given by the `max_prepared_stmt_count' system
     variable.)  This variable was added in MySQL 5.1.10. In MySQL
     5.1.14, it was converted to the global `Prepared_stmt_count'
     status variable.

   *  `protocol_version'

     *Variable Name*      `protocol_version'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          

     The version of the client/server protocol used by the MySQL server.

   *  `query_alloc_block_size'

     *Option Sets         Yes, `query_alloc_block_size'
     Variable*            
     *Variable Name*      `query_alloc_block_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default8192          
     Range1024-4294967295 

     The allocation size of memory blocks that are allocated for
     objects created during statement parsing and execution. If you
     have problems with memory fragmentation, it might help to increase
     this a bit.

   *  `query_cache_limit'

     *Option Sets         Yes, `query_cache_limit'
     Variable*            
     *Variable Name*      `query_cache_limit'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default1048576 Min   
     Value0               

     Don't cache results that are larger than this number of bytes. The
     default value is 1MB.

   *  `query_cache_min_res_unit'

     *Option Sets         Yes, `query_cache_min_res_unit'
     Variable*            
     *Variable Name*      `query_cache_min_res_unit'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default4096 Min      
     Value512             

     The minimum size (in bytes) for blocks allocated by the query
     cache. The default value is 4096 (4KB). Tuning information for
     this variable is given in *Note query-cache-configuration::.

   *  `query_cache_size'

     *Option Sets         Yes, `query_cache_size'
     Variable*            
     *Variable Name*      `query_cache_size'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric Default0 

     The amount of memory allocated for caching query results.  The
     default value is 0, which disables the query cache. The allowable
     values are multiples of 1024; other values are rounded down to the
     nearest multiple. Note that `query_cache_size' bytes of memory are
     allocated even if `query_cache_type' is set to 0. See *Note
     query-cache-configuration::, for more information.

     The query cache needs a minimum size of about 40KB to allocate its
     structures. (The exact size depends on system architecture.) If
     you set the value of `query_cache_size' too small, you'll get a
     warning, as described in *Note query-cache-configuration::.

   *  `query_cache_type'

     *Option Sets         Yes, `query_cache_type'
     Variable*            
     *Variable Name*      `query_cache_type'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     Default1 Valid       
     Values0, 1, 2        

     Set the query cache type. Setting the `GLOBAL' value sets the type
     for all clients that connect thereafter. Individual clients can set
     the `SESSION' value to affect their own use of the query cache.
     Possible values are shown in the following table:

     *Option*   *Description*
     `0' or     Don't cache results in or retrieve results
     `OFF'      from the query cache. Note that this does not
                deallocate the query cache buffer. To do that,
                you should set `query_cache_size' to 0.
     `1' or     Cache all cacheable query results except for
     `ON'       those that begin with `SELECT SQL_NO_CACHE'.
     `2' or     Cache results only for cacheable queries that
     `DEMAND'   begin with `SELECT SQL_CACHE'.

     This variable defaults to `ON'.

     Any unique prefix of a valid value may be used to set the value of
     this variable.

   *  `query_cache_wlock_invalidate'

     *Option Sets         Yes, `query_cache_wlock_invalidate'
     Variable*            
     *Variable Name*      `query_cache_wlock_invalidate'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Normally, when one client acquires a `WRITE' lock on a `MyISAM'
     table, other clients are not blocked from issuing statements that
     read from the table if the query results are present in the query
     cache. Setting this variable to 1 causes acquisition of a `WRITE'
     lock for a table to invalidate any queries in the query cache that
     refer to the table. This forces other clients that attempt to
     access the table to wait while the lock is in effect.

   *  `query_prealloc_size'

     *Option Sets         Yes, `query_prealloc_size'
     Variable*            
     *Variable Name*      `query_prealloc_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default8192          
     Range8192-4294967295 

     The size of the persistent buffer used for statement parsing and
     execution. This buffer is not freed between statements.  If you
     are running complex queries, a larger `query_prealloc_size' value
     might be helpful in improving performance, because it can reduce
     the need for the server to perform memory allocation during query
     execution operations.

   *  `range_alloc_block_size'

     *Option Sets         Yes, `range_alloc_block_size'
     Variable*            
     *Variable Name*      `range_alloc_block_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default4096 Max      
     Value4294967295      

     The size of blocks that are allocated when doing range
     optimization.

   *  `read_buffer_size'

     *Option Sets         Yes, `read_buffer_size'
     Variable*            
     *Variable Name*      `read_buffer_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default131072        
     Range8200-2147479552 

     Each thread that does a sequential scan allocates a buffer of this
     size (in bytes) for each table it scans. If you do many sequential
     scans, you might want to increase this value, which defaults to
     131072. The value of this variable should be a multiple of 4KB. If
     it is set to a value that is not a multiple of 4KB, its value will
     be rounded down to the nearest multiple of 4KB.

     The maximum allowable setting for `read_buffer_size' is 2GB.

     `read_buffer_size' and `read_rnd_buffer_size' are not specific to
     any storage engine and apply in a general manner for optimization.
     See *Note memory-use::, for example.

   *  `read_only'

     *Option Sets         Yes, `read_only'
     Variable*            
     *Variable Name*      `read_only'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric Default0 

     This variable is off by default. When it is enabled, the server
     allows no updates except from users that have the `SUPER'
     privilege or (on a slave server) from updates performed by slave
     threads. On a slave server, this can be useful to ensure that the
     slave accepts updates only from its master server and not from
     clients. This variable does not apply to `TEMPORARY' tables.

     `read_only' exists only as a `GLOBAL' variable, so changes to its
     value require the `SUPER' privilege. Changes to `read_only' on a
     master server are not replicated to slave servers. The value can
     be set on a slave server independent of the setting on the master.

     As of MySQL 5.1.15, the following conditions apply:

        * If you attempt to enable `read_only' while you have any
          explicit locks (acquired with `LOCK TABLES') or have a pending
          transaction, an error occurs.

        * If you attempt to enable `read_only' while other clients hold
          explicit table locks or have pending transactions, the
          attempt blocks until the locks are released and the
          transactions end. While the attempt to enable `read_only' is
          pending, requests by other clients for table locks or to begin
          transactions also block until `read_only' has been set.

        * `read_only' can be enabled while you hold a global read lock
          (acquired with `FLUSH TABLES WITH READ LOCK') because that
          does not involve table locks.

   *  `read_rnd_buffer_size'

     *Option Sets         Yes, `read_rnd_buffer_size'
     Variable*            
     *Variable Name*      `read_rnd_buffer_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default262144        
     Range8200-4294967295 

     When reading rows in sorted order following a key-sorting
     operation, the rows are read through this buffer to avoid disk
     seeks. See *Note order-by-optimization::.  Setting the variable to
     a large value can improve `ORDER BY' performance by a lot. However,
     this is a buffer allocated for each client, so you should not set
     the global variable to a large value. Instead, change the session
     variable only from within those clients that need to run large
     queries.

     The maximum allowable setting for `read_rnd_buffer_size' is 2GB.

     `read_buffer_size' and `read_rnd_buffer_size' are not specific to
     any storage engine and apply in a general manner for optimization.
     See *Note memory-use::, for example.

   *  `relay_log_purge'

     *Option Sets         Yes, `relay_log_purge'
     Variable*            
     *Variable Name*      `relay_log_purge'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultTRUE          

     Disables or enables automatic purging of relay log files as soon
     as they are not needed any more. The default value is 1 (`ON').

   *  `relay_log_space_limit'

     *Option Sets         Yes, `relay_log_space_limit'
     Variable*            
     *Variable Name*      `relay_log_space_limit'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric Default0 

     The maximum amount of space to use for all relay logs.

   * `report_host'

     The value of the `--report-host' option. This variable was added
     in MySQL 5.1.24.

   * `report_password'

     The value of the `--report-password' option.  This variable was
     added in MySQL 5.1.24.

   * `report_port'

     The value of the `--report-port' option. This variable was added
     in MySQL 5.1.24.

   * `report_user'

     The value of the `--report-user' option. This variable was added
     in MySQL 5.1.24.

   *  `rpl_recovery_rank'

     This variable is unused.

   *  `secure_auth'

     *Option Sets         Yes, `secure_auth'
     Variable*            
     *Variable Name*      `secure_auth'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     If the MySQL server has been started with the `--secure-auth'
     option, it blocks connections from all accounts that have
     passwords stored in the old (pre-4.1) format. In that case, the
     value of this variable is `ON', otherwise it is `OFF'.

     You should enable this option if you want to prevent all use of
     passwords employing the old format (and hence insecure
     communication over the network).

     Server startup fails with an error if this option is enabled and
     the privilege tables are in pre-4.1 format. See *Note old-client::.

   *  `secure_file_priv'

     *Version Introduced* 5.1.17
     *Option Sets         Yes, `secure_file_priv'
     Variable*            
     *Variable Name*      `secure_file_priv'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typestring           

     By default, this variable is empty. If set to the name of a
     directory, it limits the effect of the `LOAD_FILE()' function and
     the `LOAD DATA' and `SELECT ... INTO OUTFILE' statements to work
     only with files in that directory.

     This variable was added in MySQL 5.1.17.

   *  `server_id'

     *Option Sets         Yes, `server_id'
     Variable*            
     *Variable Name*      `server_id'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric Default0 

     The server ID. This value is set by the `--server-id' option. It
     is used for replication to enable master and slave servers to
     identify themselves uniquely.

   *  `shared_memory'

     *Variable Name*      `shared_memory'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Platform Specific*  windows

     (Windows only.) Whether the server allows shared-memory
     connections.

   *  `shared_memory_base_name'

     *Variable Name*      `shared_memory_base_name'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Platform Specific*  windows

     (Windows only.) The name of shared memory to use for shared-memory
     connections. This is useful when running multiple MySQL instances
     on a single physical machine. The default name is `MYSQL'. The
     name is case sensitive.

   *  `skip_external_locking'

     This is `OFF' if `mysqld' uses external locking, `ON' if external
     locking is disabled.

   * `skip_networking'

     This is `ON' if the server allows only local (non-TCP/IP)
     connections. On Unix, local connections use a Unix socket file. On
     Windows, local connections use a named pipe or shared memory. On
     NetWare, only TCP/IP connections are supported, so do not set this
     variable to `ON'. This variable can be set to `ON' with the
     `--skip-networking' option.

   *  `skip_show_database'

     This prevents people from using the `SHOW DATABASES' statement if
     they do not have the `SHOW DATABASES' privilege. This can improve
     security if you have concerns about users being able to see
     databases belonging to other users. Its effect depends on the
     `SHOW DATABASES' privilege: If the variable value is `ON', the
     `SHOW DATABASES' statement is allowed only to users who have the
     `SHOW DATABASES' privilege, and the statement displays all
     database names. If the value is `OFF', `SHOW DATABASES' is allowed
     to all users, but displays the names of only those databases for
     which the user has the `SHOW DATABASES' or other privilege.

   * `slave_compressed_protocol'

     *Option Sets         Yes, `slave_compressed_protocol'
     Variable*            
     *Variable Name*      `slave_compressed_protocol'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultFALSE         

     Whether to use compression of the slave/master protocol if both
     the slave and the master support it.

   *  `slave_exec_mode'

     *Version Introduced* 5.1.24
     *Variable Name*      `slave_exec_mode'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     DefaultSTRICT Valid  
     ValuesIDEMPOTENT,    
     STRICT               

     Controls whether `IDEMPOTENT' or `STRICT' mode is used in
     replication conflict resolution and error checking.  `IDEMPOTENT'
     mode causes suppression of some errors, including duplicate-key
     and no-key-found errors. Beginning with MySQL 5.1.23-ndb-6.2.14
     and MySQL 5.1.24, this mode should be employed in multi-master
     replication, circular replication, and some other special
     replication scenarios. `STRICT' mode is the default, and is
     suitable for most other cases.

   *  `slave_load_tmpdir'

     *Option Sets         Yes, `slave_load_tmpdir'
     Variable*            
     *Variable Name*      `slave_load_tmpdir'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         
     Default/tmp          

     The name of the directory where the slave creates temporary files
     for replicating `LOAD DATA INFILE' statements.

   *  `slave_net_timeout'

     *Option Sets         Yes, `slave_net_timeout'
     Variable*            
     *Variable Name*      `slave_net_timeout'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default3600 Min      
     Value1               

     The number of seconds to wait for more data from a master/slave
     connection before aborting the read. This timeout applies only to
     TCP/IP connections, not to connections made via Unix socket files,
     named pipes, or shared memory.

   * `slave_skip_errors'

     *Option Sets         Yes, `slave_skip_errors'
     Variable*            
     *Variable Name*      `slave_skip_errors'
     *Variable Scope*     Global
     *Dynamic Variable*   No

     Normally, replication stops when an error occurs on the slave.
     This gives you the opportunity to resolve the inconsistency in the
     data manually. This variable tells the slave SQL thread to
     continue replication when a statement returns any of the errors
     listed in the variable value.

   *  `slave_transaction_retries'

     *Option Sets         Yes, `slave_transaction_retries'
     Variable*            
     *Variable Name*      `slave_transaction_retries'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default10 Min Value0 

     If a replication slave SQL thread fails to execute a transaction
     because of an `InnoDB' deadlock or exceeded `InnoDB''s
     `innodb_lock_wait_timeout' or NDBCLUSTER's
     `TransactionDeadlockDetectionTimeout' or
     `TransactionInactiveTimeout', it automatically retries
     `slave_transaction_retries' times before stopping with an error.
     The default value is 10.

   *  `slow_launch_time'

     *Option Sets         Yes, `slow_launch_time'
     Variable*            
     *Variable Name*      `slow_launch_time'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric Default2 

     If creating a thread takes longer than this many seconds, the
     server increments the `Slow_launch_threads' status variable.

   *  `slow_query_log'

     Whether the slow query log is enabled. The value can be 0 (or
     `OFF') to disable the log or 1 (or `ON') to enable the log. The
     default value depends on whether the `--log-slow-queries' option
     is given. The destination for log output is controlled by the
     `log_output' system variable; if that value is `NONE', no log
     entries are written even if the log is enabled. The
     `slow_query_log' variable was added in MySQL 5.1.12.

   *  `slow_query_log_file'

     *Version Introduced* 5.1.12
     *Variable Name*      `slow_query_log_file'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typefilename         

     The name of the slow query log file. The default value is
     `HOST_NAME-slow.log', but the initial value can be changed with the
     `--log-slow-queries' option. This variable was added in MySQL
     5.1.12.

   * `socket'

     *Option Sets         Yes, `socket'
     Variable*            
     *Variable Name*      `socket'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typelinuxfilename    
     Default/tmp/mysql.sock
     *Value Set *         
     Typehpuxfilename     
     Default/tmp/mysql.sock
     *Value Set *         
     Typesolarisfilename  
     Default/tmp/mysql.sock
     *Value Set *         
     Typemacosxfilename   
     Default/tmp/mysql.sock

     On Unix platforms, this variable is the name of the socket file
     that is used for local client connections. The default is
     `/tmp/mysql.sock'. (For some distribution formats, the directory
     might be different, such as `/var/lib/mysql' for RPMs.)

     On Windows, this variable is the name of the named pipe that is
     used for local client connections. The default value is `MySQL'
     (not case sensitive).

   *  `sort_buffer_size'

     *Option Sets         Yes, `sort_buffer_size'
     Variable*            
     *Variable Name*      `sort_buffer_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default2097144 Max   
     Value4294967295      

     Each thread that needs to do a sort allocates a buffer of this
     size. Increase this value for faster `ORDER BY' or `GROUP BY'
     operations. See *Note temporary-files::.

     The maximum allowable setting for `sort_buffer_size' is 4GB. As of
     MySQL 5.1.23, values larger than 4GB are allowed for 64-bit
     platforms (except 64-bit Windows, for which large values are
     truncated to 4GB with a warning).

   *  `sql_mode'

     *Option Sets         Yes, `sql_mode'
     Variable*            
     *Variable Name*      `sql_mode'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     Default" Valid       
     ValuesALLOW_INVALID_DATES,
     ANSI_QUOTES,         
     ERROR_FOR_DIVISION_BY_ZERO,
     HIGH_NOT_PRECEDENCE, 
     IGNORE_SPACE,        
     NO_AUTO_CREATE_USER, 
     NO_AUTO_VALUE_ON_ZERO,
     NO_BACKSLASH_ESCAPES,
     NO_DIR_IN_CREATE,    
     NO_ENGINE_SUBSTITUTION,
     NO_FIELD_OPTIONS,    
     NO_KEY_OPTIONS,      
     NO_TABLE_OPTIONS,    
     NO_UNSIGNED_SUBTRACTION,
     NO_ZERO_DATE,        
     NO_ZERO_IN_DATE,     
     ONLY_FULL_GROUP_BY,  
     PAD_CHAR_TO_FULL_LENGTH,
     PIPES_AS_CONCAT,     
     REAL_AS_FLOAT,       
     STRICT_ALL_TABLES,   
     STRICT_TRANS_TABLES  

     The current server SQL mode, which can be set dynamically.  See
     *Note server-sql-mode::.

   *  `sql_slave_skip_counter'

     *Variable Name*      `sql_slave_skip_counter'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          

     The number of events from the master that a slave server should
     skip. See *Note set-global-sql-slave-skip-counter::.

   *  `ssl_ca'

     *Version Introduced* 5.1.11
     *Option Sets         Yes, `ssl_ca'
     Variable*            
     *Variable Name*      `ssl_ca'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The path to a file with a list of trusted SSL CAs. This variable
     was added in MySQL 5.1.11.

   *  `ssl_capath'

     *Version Introduced* 5.1.11
     *Option Sets         Yes, `ssl_capath'
     Variable*            
     *Variable Name*      `ssl_capath'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The path to a directory that contains trusted SSL CA certificates
     in PEM format. This variable was added in MySQL 5.1.11.

   *  `ssl_cert'

     *Version Introduced* 5.1.11
     *Option Sets         Yes, `ssl_cert'
     Variable*            
     *Variable Name*      `ssl_cert'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The name of the SSL certificate file to use for establishing a
     secure connection. This variable was added in MySQL 5.1.11.

   *  `ssl_cipher'

     *Version Introduced* 5.1.11
     *Option Sets         Yes, `ssl_cipher'
     Variable*            
     *Variable Name*      `ssl_cipher'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     A list of allowable ciphers to use for SSL encryption. This
     variable was added in MySQL 5.1.11.

   *  `ssl_key'

     *Version Introduced* 5.1.11
     *Option Sets         Yes, `ssl_key'
     Variable*            
     *Variable Name*      `ssl_key'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typestring           

     The name of the SSL key file to use for establishing a secure
     connection. This variable was added in MySQL 5.1.11.

   *  `storage_engine'

     *Variable Name*      `storage_engine'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      

     The default storage engine (table type). To set the storage engine
     at server startup, use the `--default-storage-engine' option. See
     *Note server-options::.

   *  `sync_binlog'

     *Option Sets         Yes, `sync_binlog'
     Variable*            
     *Variable Name*      `sync_binlog'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default0             
     Range0-4294967295    

     If the value of this variable is positive, the MySQL server
     synchronizes its binary log to disk (using `fdatasync()') after
     every `sync_binlog' writes to the binary log.  Note that there is
     one write to the binary log per statement if autocommit is
     enabled, and one write per transaction otherwise. The default
     value is 0, which does no synchronizing to disk. A value of 1 is
     the safest choice, because in the event of a crash you lose at
     most one statement or transaction from the binary log. However, it
     is also the slowest choice (unless the disk has a battery-backed
     cache, which makes synchronization very fast).

     If the value of `sync_binlog' is 0 (the default), no extra
     flushing is done. The server relies on the operating system to
     flush the file contents occasionally as for any other file.

   *  `sync_frm'

     *Option Sets         Yes, `sync_frm'
     Variable*            
     *Variable Name*      `sync_frm'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultTRUE          

     If this variable is set to 1, when any non-temporary table is
     created its `.frm' file is synchronized to disk (using
     `fdatasync()').  This is slower but safer in case of a crash. The
     default is 1.

   *  `system_time_zone'

     *Variable Name*      `system_time_zone'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typestring           

     The server system time zone. When the server begins executing, it
     inherits a time zone setting from the machine defaults, possibly
     modified by the environment of the account used for running the
     server or the startup script.  The value is used to set
     `system_time_zone'. Typically the time zone is specified by the
     `TZ' environment variable. It also can be specified using the
     `--timezone' option of the `mysqld_safe' script.

     The `system_time_zone' variable differs from `time_zone'. Although
     they might have the same value, the latter variable is used to
     initialize the time zone for each client that connects. See *Note
     time-zone-support::.

   *  `table_cache'

     *Option Sets         Yes, `table_cache'
     Variable*            
     *Variable Name*      `table_cache'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Deprecated*         5.1.3, by `table_open_cache'
     *Value Set *         
     Typenumeric          
     Default64            
     Range1-524288        

     This is the old name of `table_open_cache' before MySQL 5.1.3.
     From 5.1.3 on, use `table_open_cache' instead.

   *  `table_definition_cache'

     *Version Introduced* 5.1.3
     *Option Sets         Yes, `table_definition_cache'
     Variable*            
     *Variable Name*      `table_definition_cache'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set (<=       
     5.1.25)*             
     Typenumeric          
     Default128           
     Range1-524288        
     *Value Set (>=       
     5.1.25)*             
     Typenumeric          
     Default256           
     Range256-524288      

     The number of table definitions that can be stored in the
     definition cache. If you use a large number of tables, you can
     create a large table definition cache to speed up opening of
     tables. The table definition cache takes less space and does not
     use file descriptors, unlike the normal table cache. This variable
     was added in MySQL 5.1.3. The minimum and default values are 1 and
     128 before MySQL 5.1.25. The minimum and default are both 256 as
     of MySQL 5.1.25.

   *  `table_lock_wait_timeout'

     *Option Sets         Yes, `table_lock_wait_timeout'
     Variable*            
     *Variable Name*      `table_lock_wait_timeout'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default50            
     Range1-1073741824    

     Specifies a wait timeout for table-level locks, in seconds.  The
     default timeout is 50 seconds. The timeout is active only if the
     connection has open cursors. This variable can also be set
     globally at runtime (you need the `SUPER' privilege to do this).

   *  `table_open_cache'

     *Version Introduced* 5.1.3
     *Variable Name*      `table_open_cache'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default64            
     Range1-524288        

     The number of open tables for all threads. Increasing this value
     increases the number of file descriptors that `mysqld' requires.
     You can check whether you need to increase the table cache by
     checking the `Opened_tables' status variable. See *Note
     server-status-variables::. If the value of `Opened_tables' is
     large and you don't do `FLUSH TABLES' often (which just forces all
     tables to be closed and reopened), then you should increase the
     value of the `table_open_cache' variable. For more information
     about the table cache, see *Note table-cache::. Before MySQL
     5.1.3, this variable is called `table_cache'.

   *  `table_type'

     *Variable Name*      `table_type'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Deprecated*         5.2.5, by `storage_engine'
     *Value Set *         
     Typeenumeration      

     This variable is a synonym for `storage_engine'. In MySQL 5.1,
     `storage_engine' is the preferred name. In MySQL 6.0, `table_type'
     will be removed.

   *  `thread_cache_size'

     *Option Sets         Yes, `thread_cache_size'
     Variable*            
     *Variable Name*      `thread_cache_size'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default0             
     Range0-16384         

     How many threads the server should cache for reuse. When a client
     disconnects, the client's threads are put in the cache if there
     are fewer than `thread_cache_size' threads there. Requests for
     threads are satisfied by reusing threads taken from the cache if
     possible, and only when the cache is empty is a new thread
     created. This variable can be increased to improve performance if
     you have a lot of new connections. (Normally, this doesn't provide
     a notable performance improvement if you have a good thread
     implementation.) By examining the difference between the
     `Connections' and `Threads_created' status variables, you can see
     how efficient the thread cache is. For details, see *Note
     server-status-variables::.

   *  `thread_concurrency'

     *Option Sets         Yes, `thread_concurrency'
     Variable*            
     *Variable Name*      `thread_concurrency'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          
     Default10 Range1-512 

     On Solaris, `mysqld' calls `thr_setconcurrency()' with this value.
     This function enables applications to give the threads system a
     hint about the desired number of threads that should be run at the
     same time.

   *  `thread_handling'

     *Version Introduced* 5.1.17
     *Option Sets         Yes, `thread_handling'
     Variable*            
     *Variable Name*      `thread_handling'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typeenumeration      
     Valid                
     Valuesno-threads,    
     one-thread-per-connection

     The thread-handling model. The allowable values are `one-thread'
     (the server uses one thread) and `one-thread-per-connection' (the
     server uses one thread to handle each client connection).
     `one-thread' is useful for debugging under Linux; see MySQL
     Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting). This
     variable was added in MySQL 5.1.17

   *  `thread_stack'

     *Option Sets         Yes, `thread_stack'
     Variable*            
     *Variable Name*      `thread_stack'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric          
     Default196608        
     Range131072-4294967295

     The stack size for each thread. Many of the limits detected by the
     `crash-me' test are dependent on this value. See *Note
     mysql-benchmarks::. The default (192KB) is large enough for normal
     operation. If the thread stack size is too small, it limits the
     complexity of the SQL statements that the server can handle, the
     recursion depth of stored procedures, and other memory-consuming
     actions.

   *  `time_format'

     This variable is unused.

   *  `time_zone'

     *Variable Name*      `time_zone'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typestring           

     The current time zone. This variable is used to initialize the
     time zone for each client that connects. By default, the initial
     value of this is `'SYSTEM'' (which means, `use the value of
     `system_time_zone''). The value can be specified explicitly at
     server startup with the `--default-time-zone' option. See *Note
     time-zone-support::.

   *  `timed_mutexes'

     *Option Sets         Yes, `timed_mutexes'
     Variable*            
     *Variable Name*      `timed_mutexes'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultOFF           

     This variable controls whether `InnoDB' mutexes are timed. If this
     variable is set to 0 or `OFF' (the default), mutex timing is
     disabled. If the variable is set to 1 or `ON', mutex timing is
     enabled. With timing enabled, the `os_wait_times' value in the
     output from `SHOW ENGINE INNODB MUTEX' indicates the amount of
     time (in ms) spent in operating system waits. Otherwise, the value
     is 0.

   *  `tmp_table_size'

     *Option Sets         Yes, `tmp_table_size'
     Variable*            
     *Variable Name*      `tmp_table_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Defaultsystem        
     dependent            
     Range1024-4294967295 

     The maximum size of internal in-memory temporary tables.  (The
     actual limit is determined as the smaller of `max_heap_table_size'
     and `tmp_table_size'.) If an in-memory temporary table exceeds the
     limit, MySQL automatically converts it to an on-disk `MyISAM'
     table.  Increase the value of `tmp_table_size' (and
     `max_heap_table_size' if necessary) if you do many advanced `GROUP
     BY' queries and you have lots of memory. This variable does not
     apply to user-created `MEMORY' tables.

   * `tmpdir'

     *Option Sets         Yes, `tmpdir'
     Variable*            
     *Variable Name*      `tmpdir'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typefilename         

     The directory used for temporary files and temporary tables.  This
     variable can be set to a list of several paths that are used in
     round-robin fashion. Paths should be separated by colon characters
     (``:'') on Unix and semicolon characters (``;'') on Windows,
     NetWare, and OS/2.

     The multiple-directory feature can be used to spread the load
     between several physical disks. If the MySQL server is acting as a
     replication slave, you should not set `tmpdir' to point to a
     directory on a memory-based filesystem or to a directory that is
     cleared when the server host restarts. A replication slave needs
     some of its temporary files to survive a machine restart so that
     it can replicate temporary tables or `LOAD DATA INFILE'
     operations. If files in the temporary file directory are lost when
     the server restarts, replication fails. However, if you are using
     MySQL 4.0.0 or later, you can set the slave's temporary directory
     using the `slave_load_tmpdir' variable. In that case, the slave
     won't use the general `tmpdir' value and you can set `tmpdir' to a
     non-permanent location.

   *  `transaction_alloc_block_size'

     *Option Sets         Yes, `transaction_alloc_block_size'
     Variable*            
     *Variable Name*      `transaction_alloc_block_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default8192          
     Range1024-4294967295 

     The amount in bytes by which to increase a per-transaction memory
     pool which needs memory. See the description of
     `transaction_prealloc_size'.

   *  `transaction_prealloc_size'

     *Option Sets         Yes, `transaction_prealloc_size'
     Variable*            
     *Variable Name*      `transaction_prealloc_size'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default4096          

     There is a per-transaction memory pool from which various
     transaction-related allocations take memory. The initial size of
     the pool in bytes is `transaction_prealloc_size'. For every
     allocation that cannot be satisfied from the pool because it has
     insufficient memory available, the pool is increased by
     `transaction_alloc_block_size' bytes. When the transaction ends,
     the pool is truncated to `transaction_prealloc_size' bytes.

     By making `transaction_prealloc_size' sufficiently large to
     contain all statements within a single transaction, you can avoid
     many `malloc()' calls.

   *  `tx_isolation'

     *Variable Name*      `tx_isolation'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeenumeration      
     DefaultREPEATABLE-READ
     Valid                
     ValuesREAD-UNCOMMITTED,
     READ-COMMITTED,      
     REPEATABLE-READ,     
     SERIALIZABLE         

     The default transaction isolation level. Defaults to
     `REPEATABLE-READ'.

     This variable is set by the `SET TRANSACTION ISOLATION LEVEL'
     statement. See *Note set-transaction::. If you set `tx_isolation'
     directly to an isolation level name that contains a space, the
     name should be enclosed within quotes, with the space replaced by
     a dash.  For example:

          SET tx_isolation = 'READ-COMMITTED';

     Any unique prefix of a valid value may be used to set the value of
     this variable.

   *  `updatable_views_with_limit'

     *Option Sets         Yes, `updatable_views_with_limit'
     Variable*            
     *Variable Name*      `updatable_views_with_limit'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean Default1 

     This variable controls whether updates to a view can be made when
     the view does not contain all columns of the primary key defined
     in the underlying table, if the update statement contains a
     `LIMIT' clause. (Such updates often are generated by GUI tools.)
     An update is an `UPDATE' or `DELETE' statement. Primary key here
     means a `PRIMARY KEY', or a `UNIQUE' index in which no column can
     contain `NULL'.

     The variable can have two values:

        * `1' or `YES': Issue a warning only (not an error message).
          This is the default value.

        * `0' or `NO': Prohibit the update.

   * `version'

     The version number for the server.

   *  `version_comment'

     The `configure' script has a `--with-comment' option that allows a
     comment to be specified when building MySQL. This variable contains
     the value of that comment.

   *  `version_compile_machine'

     The type of machine or architecture on which MySQL was built.

   *  `version_compile_os'

     *Variable Name*      `version_compile_os'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typestring           

     The type of operating system on which MySQL was built.

   *  `wait_timeout'

     The number of seconds the server waits for activity on a
     non-interactive connection before closing it. This timeout applies
     only to TCP/IP and Unix socket file connections, not to
     connections made via named pipes, or shared memory.

     On thread startup, the session `wait_timeout' value is initialized
     from the global `wait_timeout' value or from the global
     `interactive_timeout' value, depending on the type of client (as
     defined by the `CLIENT_INTERACTIVE' connect option to *Note
     `mysql_real_connect()': mysql-real-connect.). See also
     `interactive_timeout'.

MySQL Enterprise

Expert use of server system variables is part of the service offered by
the MySQL Enterprise Monitor. To subscribe, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: server-session-variables,  Next: using-system-variables,  Prev: server-system-variables,  Up: mysqld-server

5.1.4 Session System Variables
------------------------------

Several system variables exist only as session variables. These cannot
be set at server startup but can be assigned values at runtime using
the `SET' statement (except for those that are read only). Most of them
are not displayed by `SHOW VARIABLES', but you can obtain their values
using `SELECT'. This section describes the session system variables.
For information about setting or displaying their values, see *Note
using-system-variables::. For example:

     mysql> SELECT @@AUTOCOMMIT;
     +--------------+
     | @@AUTOCOMMIT |
     +--------------+
     |            1 |
     +--------------+

The lettercase of these variables does not matter.

The following table lists the system variables that have only session
scope:

*Name*                        *Cmd-Line**Option   *System   *Dynamic*
                                        file*     Var*      
autocommit                                        Yes       Yes
big-tables                    Yes       Yes                 
- _Variable_: big_tables                          Yes       Yes
error_count                                       Yes       No
foreign_key_checks                                Yes       Yes
identity                                          Yes       Yes
insert_id                                         Yes       Yes
last_insert_id                                    Yes       Yes
ndb_table_no_logging                              Yes       Yes
ndb_table_temporary                               Yes       Yes
sql_auto_is_null                                  Yes       Yes
sql_big_selects                                   Yes       Yes
sql_big_tables                                    Yes       Yes
sql_buffer_result                                 Yes       Yes
sql_log_bin                                       Yes       Yes
sql_log_off                                       Yes       Yes
sql_log_update                                    Yes       Yes
sql_notes                                         Yes       Yes
sql_quote_show_create                             Yes       Yes
sql_safe_updates                                  Yes       Yes
sql_warnings                                      Yes       Yes
timestamp                                         Yes       Yes
transaction_allow_batching                        Yes       Yes
unique_checks                                     Yes       Yes
warning_count                                     Yes       No

   *  `AUTOCOMMIT = {0 | 1}'

     Set the autocommit mode. If set to 1, all changes to a table take
     effect immediately. If set to 0 you have to use `COMMIT' to accept
     a transaction or `ROLLBACK' to cancel it. By default, client
     connections begin with `AUTOCOMMIT' set to 1. If you change
     `AUTOCOMMIT' mode from 0 to 1, MySQL performs an automatic `COMMIT'
     of any open transaction. Another way to begin a transaction is to
     use a `START TRANSACTION' or `BEGIN' statement. See *Note commit::.

   * `BIG_TABLES = {0 | 1}'

     If set to 1, all temporary tables are stored on disk rather than
     in memory. This is a little slower, but the error `The table
     TBL_NAME is full' does not occur for `SELECT' operations that
     require a large temporary table. The default value for a new
     connection is 0 (use in-memory temporary tables). Normally, you
     should never need to set this variable, because in-memory tables
     are automatically converted to disk-based tables as required.

     *Note*:

     This variable was formerly named `SQL_BIG_TABLES'.

   *  `ERROR_COUNT'

     The number of errors that resulted from the last statement that
     generated messages. This variable is read only. See *Note
     show-errors::.

   *  `FOREIGN_KEY_CHECKS = {0 | 1}'

     If set to 1 (the default), foreign key constraints for `InnoDB'
     tables are checked. If set to 0, they are ignored. Disabling
     foreign key checking can be useful for reloading `InnoDB' tables
     in an order different from that required by their parent/child
     relationships. See *Note innodb-foreign-key-constraints::.

     Setting `FOREIGN_KEY_CHECKS' to 0 also affects data definition
     statements: `DROP SCHEMA' drops a schema even if it contains tables
     that have foreign keys that are referred to by tables outside the
     schema, and `DROP TABLE' drops tables that have foreign keys that
     are referred to by other tables.

     *Note*:

     Setting `FOREIGN_KEY_CHECKS' to 1 does not trigger a scan of the
     existing table data. Therefore, rows added to the table while
     `FOREIGN_KEY_CHECKS=0' will not be verified for consistency.

   *  `IDENTITY = VALUE'

     This variable is a synonym for the `LAST_INSERT_ID' variable. It
     exists for compatibility with other database systems. You can read
     its value with `SELECT @@IDENTITY', and set it using `SET
     IDENTITY'.

   *  `INSERT_ID = VALUE'

     Set the value to be used by the following `INSERT' or `ALTER TABLE'
     statement when inserting an `AUTO_INCREMENT' value. This is mainly
     used with the binary log.

   *  `LAST_INSERT_ID = VALUE'

     Set the value to be returned from `LAST_INSERT_ID()'. This is
     stored in the binary log when you use `LAST_INSERT_ID()' in a
     statement that updates a table. Setting this variable does not
     update the value returned by the *Note `mysql_insert_id()':
     mysql-insert-id. C API function.

   *  `SQL_AUTO_IS_NULL = {0 | 1}'

     If set to 1 (the default), you can find the last inserted row for
     a table that contains an `AUTO_INCREMENT' column by using the
     following construct:

          WHERE AUTO_INCREMENT_COLUMN IS NULL

     This behavior is used by some ODBC programs, such as Access.

   *  `SQL_BIG_SELECTS = {0 | 1}'

     If set to 0, MySQL aborts `SELECT' statements that are likely to
     take a very long time to execute (that is, statements for which
     the optimizer estimates that the number of examined rows exceeds
     the value of `max_join_size'). This is useful when an inadvisable
     `WHERE' statement has been issued. The default value for a new
     connection is 1, which allows all `SELECT' statements.

     If you set the `max_join_size' system variable to a value other
     than `DEFAULT', `SQL_BIG_SELECTS' is set to 0.

   *  `SQL_BUFFER_RESULT = {0 | 1}'

     If set to 1, `SQL_BUFFER_RESULT' forces results from `SELECT'
     statements to be put into temporary tables. This helps MySQL free
     the table locks early and can be beneficial in cases where it
     takes a long time to send results to the client. The default value
     is 0.

   *  `SQL_LOG_BIN = {0 | 1}'

     If set to 0, no logging is done to the binary log for the client.
     The client must have the `SUPER' privilege to set this option. The
     default value is 1.

   *  `SQL_LOG_OFF = {0 | 1}'

     If set to 1, no logging is done to the general query log for this
     client. The client must have the `SUPER' privilege to set this
     option. The default value is 0.

   *  `SQL_LOG_UPDATE = {0 | 1}'

     This variable is deprecated, and is mapped to `SQL_LOG_BIN'.

   *  `SQL_NOTES = {0 | 1}'

     If set to 1 (the default), warnings of `Note' level are recorded.
     If set to 0, `Note' warnings are suppressed.  `mysqldump' includes
     output to set this variable to 0 so that reloading the dump file
     does not produce warnings for events that do not affect the
     integrity of the reload operation.

   *  `SQL_QUOTE_SHOW_CREATE = {0 | 1}'

     If set to 1 (the default), the server quotes identifiers for `SHOW
     CREATE TABLE' and `SHOW CREATE DATABASE' statements. If set to 0,
     quoting is disabled. This option is enabled by default so that
     replication works for identifiers that require quoting. See *Note
     show-create-table::, and *Note show-create-database::.

   *  `SQL_SAFE_UPDATES = {0 | 1}'

     If set to 1, MySQL aborts `UPDATE' or `DELETE' statements that do
     not use a key in the `WHERE' clause or a `LIMIT' clause. This
     makes it possible to catch `UPDATE' or `DELETE' statements where
     keys are not used properly and that would probably change or
     delete a large number of rows. The default value is 0.

   *  `SQL_SELECT_LIMIT = {VALUE | DEFAULT}'

     The maximum number of rows to return from `SELECT' statements. The
     default value for a new connection is the maximum number of rows
     that the server allows per table, which depends on the server
     configuration and may be affected if the server build was
     configured with `--with-big-tables'. Typical default values are
     (2^32)-1 or (2^64)-1. If you have changed the limit, the default
     value can be restored by assigning a value of `DEFAULT'.

     If a `SELECT' has a `LIMIT' clause, the `LIMIT' takes precedence
     over the value of `SQL_SELECT_LIMIT'.

     `SQL_SELECT_LIMIT' does not apply to `SELECT' statements executed
     within stored routines. It also does not apply to `SELECT'
     statements that do not produce a result set to be returned to the
     client. These include `SELECT' statements in subqueries, `CREATE
     TABLE ... SELECT', and `INSERT INTO ... SELECT'.

   *  `SQL_WARNINGS = {0 | 1}'

     This variable controls whether single-row `INSERT' statements
     produce an information string if warnings occur. The default is 0.
     Set the value to 1 to produce an information string.

   *  `TIMESTAMP = {TIMESTAMP_VALUE | DEFAULT}'

     Set the time for this client. This is used to get the original
     timestamp if you use the binary log to restore rows.
     `timestamp_value' should be a Unix epoch timestamp, not a MySQL
     timestamp.

     `SET TIMESTAMP' affects the value returned by `NOW()' but not by
     `SYSDATE()'. This means that timestamp settings in the binary log
     have no effect on invocations of `SYSDATE()'.  The server can be
     started with the `--sysdate-is-now' option to cause `SYSDATE()' to
     be an alias for `NOW()', in which case `SET TIMESTAMP' affects
     both functions.

   *  `UNIQUE_CHECKS = {0 | 1}'

     If set to 1 (the default), uniqueness checks for secondary indexes
     in `InnoDB' tables are performed.  If set to 0, storage engines
     are allowed to assume that duplicate keys are not present in input
     data. If you know for certain that your data does not contain
     uniqueness violations, you can set this to 0 to speed up large
     table imports to `InnoDB'.

     Note that setting this variable to 0 does not _require_ storage
     engines to ignore duplicate keys. An engine is still allowed to
     check for them and issue duplicate-key errors if it detects them.

   *  `WARNING_COUNT'

     The number of errors, warnings, and notes that resulted from the
     last statement that generated messages. This variable is read
     only. See *Note show-warnings::.


File: manual.info,  Node: using-system-variables,  Next: server-status-variables,  Prev: server-session-variables,  Up: mysqld-server

5.1.5 Using System Variables
----------------------------

* Menu:

* structured-system-variables::  Structured System Variables
* dynamic-system-variables::     Dynamic System Variables

The MySQL server maintains many system variables that indicate how it
is configured. *Note server-system-variables::, describes the meaning
of these variables. Each system variable has a default value. System
variables can be set at server startup using options on the command
line or in an option file.  Most of them can be changed dynamically
while the server is running by means of the `SET' statement, which
enables you to modify operation of the server without having to stop
and restart it. You can refer to system variable values in expressions.

The server maintains two kinds of system variables. Global variables
affect the overall operation of the server. Session variables affect
its operation for individual client connections. A given system
variable can have both a global and a session value. Global and session
system variables are related as follows:

   * When the server starts, it initializes all global variables to
     their default values. These defaults can be changed by options
     specified on the command line or in an option file.  (See *Note
     program-options::.)

   * The server also maintains a set of session variables for each
     client that connects. The client's session variables are
     initialized at connect time using the current values of the
     corresponding global variables. For example, the client's SQL mode
     is controlled by the session `sql_mode' value, which is
     initialized when the client connects to the value of the global
     `sql_mode' value.

System variable values can be set globally at server startup by using
options on the command line or in an option file. When you use a
startup option to set a variable that takes a numeric value, the value
can be given with a suffix of `K', `M', or `G' (either uppercase or
lowercase) to indicate a multiplier of 1024, 1024^2 or 1024^3; that is,
units of kilobytes, megabytes, or gigabytes, respectively. Thus, the
following command starts the server with a query cache size of 16
megabytes and a maximum packet size of one gigabyte:

     mysqld --query_cache_size=16M --max_allowed_packet=1G

Within an option file, those variables are set like this:

     [mysqld]
     query_cache_size=16M
     max_allowed_packet=1G

The lettercase of suffix letters does not matter; `16M' and `16m' are
equivalent, as are `1G' and `1g'.

If you want to restrict the maximum value to which a system variable
can be set at runtime with the `SET' statement, you can specify this
maximum by using an option of the form `--maximum-VAR_NAME=VALUE' at
server startup. For example, to prevent the value of `query_cache_size'
from being increased to more than 32MB at runtime, use the option
`--maximum-query_cache_size=32M'.

Many system variables are dynamic and can be changed while the server
runs by using the `SET' statement. For a list, see *Note
dynamic-system-variables::. To change a system variable with `SET',
refer to it as VAR_NAME, optionally preceded by a modifier:

   * To indicate explicitly that a variable is a global variable,
     precede its name by `GLOBAL' or `@@global.'. The `SUPER' privilege
     is required to set global variables.

   * To indicate explicitly that a variable is a session variable,
     precede its name by `SESSION', `@@session.', or `@@'.  Setting a
     session variable requires no special privilege, but a client can
     change only its own session variables, not those of any other
     client.

   * `LOCAL' and `@@local.' are synonyms for `SESSION' and `@@session.'.

   * If no modifier is present, `SET' changes the session variable.

A `SET' statement can contain multiple variable assignments, separated
by commas. If you set several system variables, the most recent
`GLOBAL' or `SESSION' modifier in the statement is used for following
variables that have no modifier specified.

Examples:

     SET sort_buffer_size=10000;
     SET @@local.sort_buffer_size=10000;
     SET GLOBAL sort_buffer_size=1000000, SESSION sort_buffer_size=1000000;
     SET @@sort_buffer_size=1000000;
     SET @@global.sort_buffer_size=1000000, @@local.sort_buffer_size=1000000;

The `@@VAR_NAME' syntax for system variables is supported for
compatibility with some other database systems.

If you change a session system variable, the value remains in effect
until your session ends or until you change the variable to a different
value. The change is not visible to other clients.

If you change a global system variable, the value is remembered and
used for new connections until the server restarts. (To make a global
system variable setting permanent, you should set it in an option
file.) The change is visible to any client that accesses that global
variable. However, the change affects the corresponding session
variable only for clients that connect after the change. The global
variable change does not affect the session variable for any client
that is currently connected (not even that of the client that issues
the `SET GLOBAL' statement).

To prevent incorrect usage, MySQL produces an error if you use `SET
GLOBAL' with a variable that can only be used with `SET SESSION' or if
you do not specify `GLOBAL' (or `@@global.') when setting a global
variable.

To set a `SESSION' variable to the `GLOBAL' value or a `GLOBAL' value
to the compiled-in MySQL default value, use the `DEFAULT' keyword. For
example, the following two statements are identical in setting the
session value of `max_join_size' to the global value:

     SET max_join_size=DEFAULT;
     SET @@session.max_join_size=@@global.max_join_size;

Not all system variables can be set to `DEFAULT'. In such cases, use of
`DEFAULT' results in an error.

You can refer to the values of specific global or sesson system
variables in expressions by using one of the `@@'-modifiers. For
example, you can retrieve values in a `SELECT' statement like this:

     SELECT @@global.sql_mode, @@session.sql_mode, @@sql_mode;

When you refer to a system variable in an expression as `@@VAR_NAME'
(that is, when you do not specify `@@global.' or `@@session.'), MySQL
returns the session value if it exists and the global value otherwise.
(This differs from `SET @@VAR_NAME = VALUE', which always refers to the
session value.)

Suffixes for specifying a value multiplier can be used when setting a
variable at server startup, but not to set the value with `SET' at
runtime. On the other hand, with `SET' you can assign a variable's
value using an expression, which is not true when you set a variable at
server startup. For example, the first of the following lines is legal
at server startup, but the second is not:

     shell> mysql --max_allowed_packet=16M
     shell> mysql --max_allowed_packet=16*1024*1024

Conversely, the second of the following lines is legal at runtime, but
the first is not:

     mysql> SET GLOBAL max_allowed_packet=16M;
     mysql> SET GLOBAL max_allowed_packet=16*1024*1024;

*Note*:

Some system variables can be enabled with the `SET' statement by
setting them to `ON' or `1', or disabled by setting them to `OFF' or
`0'. However, to set such a variable on the command line or in an
option file, you must set it to `1' or `0'; setting it to `ON' or `OFF'
will not work.  For example, on the command line, `--delay_key_write=1'
works but `--delay_key_write=ON' does not.

To display system variable names and values, use the `SHOW VARIABLES'
statement:

     mysql> SHOW VARIABLES;
     +---------------------------------+-----------------------------------+
     | Variable_name                   | Value                             |
     +---------------------------------+-----------------------------------+
     | auto_increment_increment        | 1                                 |
     | auto_increment_offset           | 1                                 |
     | automatic_sp_privileges         | ON                                |
     | back_log                        | 50                                |
     | basedir                         | /home/mysql/                      |
     | binlog_cache_size               | 32768                             |
     | bulk_insert_buffer_size         | 8388608                           |
     | character_set_client            | latin1                            |
     | character_set_connection        | latin1                            |
     | character_set_database          | latin1                            |
     | character_set_results           | latin1                            |
     | character_set_server            | latin1                            |
     | character_set_system            | utf8                              |
     | character_sets_dir              | /home/mysql/share/mysql/charsets/ |
     | collation_connection            | latin1_swedish_ci                 |
     | collation_database              | latin1_swedish_ci                 |
     | collation_server                | latin1_swedish_ci                 |
     ...
     | innodb_additional_mem_pool_size | 1048576                           |
     | innodb_autoextend_increment     | 8                                 |
     | innodb_buffer_pool_size         | 8388608                           |
     | innodb_checksums                | ON                                |
     | innodb_commit_concurrency       | 0                                 |
     | innodb_concurrency_tickets      | 500                               |
     | innodb_data_file_path           | ibdata1:10M:autoextend            |
     | innodb_data_home_dir            |                                   |
     ...
     | version                         | 5.1.6-alpha-log                   |
     | version_comment                 | Source distribution               |
     | version_compile_machine         | i686                              |
     | version_compile_os              | suse-linux                        |
     | wait_timeout                    | 28800                             |
     +---------------------------------+-----------------------------------+

With a `LIKE' clause, the statement displays only those variables that
match the pattern.  To obtain a specific variable name, use a `LIKE'
clause as shown:

     SHOW VARIABLES LIKE 'max_join_size';
     SHOW SESSION VARIABLES LIKE 'max_join_size';

To get a list of variables whose name match a pattern, use the ``%''
wildcard character in a `LIKE' clause:

     SHOW VARIABLES LIKE '%size%';
     SHOW GLOBAL VARIABLES LIKE '%size%';

Wildcard characters can be used in any position within the pattern to
be matched. Strictly speaking, because ``_'' is a wildcard that matches
any single character, you should escape it as ``\_'' to match it
literally. In practice, this is rarely necessary.

For `SHOW VARIABLES', if you specify neither `GLOBAL' nor `SESSION',
MySQL returns `SESSION' values.

The reason for requiring the `GLOBAL' keyword when setting
`GLOBAL'-only variables but not when retrieving them is to prevent
problems in the future. If we were to remove a `SESSION' variable that
has the same name as a `GLOBAL' variable, a client with the `SUPER'
privilege might accidentally change the `GLOBAL' variable rather than
just the `SESSION' variable for its own connection.  If we add a
`SESSION' variable with the same name as a `GLOBAL' variable, a client
that intends to change the `GLOBAL' variable might find only its own
`SESSION' variable changed.


File: manual.info,  Node: structured-system-variables,  Next: dynamic-system-variables,  Prev: using-system-variables,  Up: using-system-variables

5.1.5.1 Structured System Variables
...................................

A structured variable differs from a regular system variable in two
respects:

   * Its value is a structure with components that specify server
     parameters considered to be closely related.

   * There might be several instances of a given type of structured
     variable. Each one has a different name and refers to a different
     resource maintained by the server.

MySQL 5.1 supports one structured variable type, which specifies
parameters governing the operation of key caches. A key cache
structured variable has these components:

   * `key_buffer_size'

   * `key_cache_block_size'

   * `key_cache_division_limit'

   * `key_cache_age_threshold'

This section describes the syntax for referring to structured
variables. Key cache variables are used for syntax examples, but
specific details about how key caches operate are found elsewhere, in
*Note myisam-key-cache::.

To refer to a component of a structured variable instance, you can use
a compound name in INSTANCE_NAME.COMPONENT_NAME format. Examples:

     hot_cache.key_buffer_size
     hot_cache.key_cache_block_size
     cold_cache.key_cache_block_size

For each structured system variable, an instance with the name of
`default' is always predefined. If you refer to a component of a
structured variable without any instance name, the `default' instance is
used. Thus, `default.key_buffer_size' and `key_buffer_size' both refer
to the same system variable.

Structured variable instances and components follow these naming rules:

   * For a given type of structured variable, each instance must have a
     name that is unique _within_ variables of that type.  However,
     instance names need not be unique _across_ structured variable
     types. For example, each structured variable has an instance named
     `default', so `default' is not unique across variable types.

   * The names of the components of each structured variable type must
     be unique across all system variable names. If this were not true
     (that is, if two different types of structured variables could
     share component member names), it would not be clear which default
     structured variable to use for references to member names that are
     not qualified by an instance name.

   * If a structured variable instance name is not legal as an unquoted
     identifier, refer to it as a quoted identifier using backticks.
     For example, `hot-cache' is not legal, but ``hot-cache`' is.

   * `global', `session', and `local' are not legal instance names.
     This avoids a conflict with notation such as `@@global.VAR_NAME'
     for referring to non-structured system variables.

Currently, the first two rules have no possibility of being violated
because the only structured variable type is the one for key caches.
These rules will assume greater significance if some other type of
structured variable is created in the future.

With one exception, you can refer to structured variable components
using compound names in any context where simple variable names can
occur. For example, you can assign a value to a structured variable
using a command-line option:

     shell> mysqld --hot_cache.key_buffer_size=64K

In an option file, use this syntax:

     [mysqld]
     hot_cache.key_buffer_size=64K

If you start the server with this option, it creates a key cache named
`hot_cache' with a size of 64KB in addition to the default key cache
that has a default size of 8MB.

Suppose that you start the server as follows:

     shell> mysqld --key_buffer_size=256K \
              --extra_cache.key_buffer_size=128K \
              --extra_cache.key_cache_block_size=2048

In this case, the server sets the size of the default key cache to
256KB. (You could also have written `--default.key_buffer_size=256K'.)
In addition, the server creates a second key cache named `extra_cache'
that has a size of 128KB, with the size of block buffers for caching
table index blocks set to 2048 bytes.

The following example starts the server with three different key caches
having sizes in a 3:1:1 ratio:

     shell> mysqld --key_buffer_size=6M \
              --hot_cache.key_buffer_size=2M \
              --cold_cache.key_buffer_size=2M

Structured variable values may be set and retrieved at runtime as well.
For example, to set a key cache named `hot_cache' to a size of 10MB,
use either of these statements:

     mysql> SET GLOBAL hot_cache.key_buffer_size = 10*1024*1024;
     mysql> SET @@global.hot_cache.key_buffer_size = 10*1024*1024;

To retrieve the cache size, do this:

     mysql> SELECT @@global.hot_cache.key_buffer_size;

However, the following statement does not work. The variable is not
interpreted as a compound name, but as a simple string for a `LIKE'
pattern-matching operation:

     mysql> SHOW GLOBAL VARIABLES LIKE 'hot_cache.key_buffer_size';

This is the exception to being able to use structured variable names
anywhere a simple variable name may occur.


File: manual.info,  Node: dynamic-system-variables,  Prev: structured-system-variables,  Up: using-system-variables

5.1.5.2 Dynamic System Variables
................................

Many server system variables are dynamic and can be set at runtime
using `SET GLOBAL' or `SET SESSION'. You can also obtain their values
using `SELECT'. See *Note using-system-variables::.

The following table shows the full list of all dynamic system
variables. The last column indicates for each variable whether `GLOBAL'
or `SESSION' (or both) apply. The table also lists session options that
can be set with the `SET' statement.  *Note server-session-variables::,
discusses these options.

Variables that have a type of `string' take a string value. Variables
that have a type of `numeric' take a numeric value. Variables that have
a type of `boolean' can be set to 0, 1, `ON' or `OFF'. (If you set them
on the command line or in an option file, use the numeric values.)
Variables that are marked as `enumeration' normally should be set to
one of the available values for the variable, but can also be set to
the number that corresponds to the desired enumeration value.  For
enumerated system variables, the first enumeration value corresponds to
0. This differs from `ENUM' columns, for which the first enumeration
value corresponds to 1.

*Variable Name*                             *Variable      *Variable
                                            Type*          Scope*
`autocommit'                                boolean        `SESSION'
`auto_increment_increment'                  numeric        `GLOBAL' |
                                                           `SESSION'
`auto_increment_offset'                     numeric        `GLOBAL' |
                                                           `SESSION'
`automatic_sp_privileges'                   boolean        `GLOBAL'
`big_tables'                                boolean        `SESSION'
`binlog_cache_size'                         numeric        `GLOBAL'
`binlog_format'                             enumeration    `GLOBAL' |
                                                           `SESSION'
`bulk_insert_buffer_size'                   numeric        `GLOBAL' |
                                                           `SESSION'
`character_set_client'                      string         `GLOBAL' |
                                                           `SESSION'
`character_set_connection'                  string         `GLOBAL' |
                                                           `SESSION'
`character_set_database'                    string         `GLOBAL' |
                                                           `SESSION'
`character_set_filesystem'                  string         `GLOBAL' |
                                                           `SESSION'
`character_set_results'                     string         `GLOBAL' |
                                                           `SESSION'
`character_set_server'                      string         `GLOBAL' |
                                                           `SESSION'
`collation_connection'                      string         `GLOBAL' |
                                                           `SESSION'
`collation_database'                        string         `GLOBAL' |
                                                           `SESSION'
`collation_server'                          string         `GLOBAL' |
                                                           `SESSION'
`completion_type'                           numeric        `GLOBAL' |
                                                           `SESSION'
`concurrent_insert'                         boolean        `GLOBAL'
`connect_timeout'                           numeric        `GLOBAL'
`date_format'                               string         `GLOBAL' |
                                                           `SESSION'
`datetime_format'                           string         `GLOBAL' |
                                                           `SESSION'
`debug'                                     string         `GLOBAL' |
                                                           `SESSION'
`default_week_format'                       numeric        `GLOBAL' |
                                                           `SESSION'
`delayed_insert_limit'                      numeric        `GLOBAL'
`delayed_insert_timeout'                    numeric        `GLOBAL'
`delayed_queue_size'                        numeric        `GLOBAL'
`delay_key_write'                           enumeration    `GLOBAL'
`div_precision_increment'                   numeric        `GLOBAL' |
                                                           `SESSION'
`engine_condition_pushdown'                 boolean        `GLOBAL' |
                                                           `SESSION'
`event-scheduler'                           enumeration    `GLOBAL'
`expire_logs_days'                          numeric        `GLOBAL'
`flush'                                     boolean        `GLOBAL'
`flush_time'                                numeric        `GLOBAL'
`foreign_key_checks'                        boolean        `SESSION'
`ft_boolean_syntax'                         string         `GLOBAL'
`general_log'                               boolean        `GLOBAL'
`general_log_file'                          filename       `GLOBAL'
`group_concat_max_len'                      numeric        `GLOBAL' |
                                                           `SESSION'
`identity'                                  numeric        `SESSION'
`init_connect'                              string         `GLOBAL'
`init_slave'                                string         `GLOBAL'
`innodb_autoextend_increment'               numeric        `GLOBAL'
`innodb_commit_concurrency'                 numeric        `GLOBAL'
`innodb_concurrency_tickets'                numeric        `GLOBAL'
`innodb_fast_shutdown'                      boolean        `GLOBAL'
`innodb_flush_log_at_trx_commit'            numeric        `GLOBAL'
`innodb_max_dirty_pages_pct'                numeric        `GLOBAL'
`innodb_max_purge_lag'                      numeric        `GLOBAL'
`innodb_support_xa'                         boolean        `GLOBAL' |
                                                           `SESSION'
`innodb_sync_spin_loops'                    numeric        `GLOBAL'
`innodb_table_locks'                        boolean        `GLOBAL' |
                                                           `SESSION'
`innodb_thread_concurrency'                 numeric        `GLOBAL'
`innodb_thread_sleep_delay'                 numeric        `GLOBAL'
`insert_id'                                 numeric        `SESSION'
`interactive_timeout'                       numeric        `GLOBAL' |
                                                           `SESSION'
`join_buffer_size'                          numeric        `GLOBAL' |
                                                           `SESSION'
`keep_files_on_create'                      boolean        `GLOBAL' |
                                                           `SESSION'
`key_buffer_size'                           numeric        `GLOBAL'
`key_cache_age_threshold'                   numeric        `GLOBAL'
`key_cache_block_size'                      numeric        `GLOBAL'
`key_cache_division_limit'                  numeric        `GLOBAL'
`last_insert_id'                            numeric        `SESSION'
`lc_time_names'                             string         `GLOBAL' |
                                                           `SESSION'
`local_infile'                                             `GLOBAL'
`log'                                       string         `GLOBAL'
`log_bin_trust_function_creators'           boolean        `GLOBAL'
`log_bin_trust_routine_creators'            boolean        `GLOBAL'
`log_output'                                enumeration    `GLOBAL'
`log_queries_not_using_indexes'             boolean        `GLOBAL'
`log_slow_queries'                          boolean        `GLOBAL'
`log-warnings'                              numeric        `GLOBAL' |
                                                           `SESSION'
`long_query_time'                           numeric        `GLOBAL' |
                                                           `SESSION'
`low_priority_updates'                      boolean        `GLOBAL' |
                                                           `SESSION'
`max_allowed_packet'                        numeric        `GLOBAL' |
                                                           `SESSION'
`max_binlog_cache_size'                     numeric        `GLOBAL'
`max_binlog_size'                           numeric        `GLOBAL'
`max_connect_errors'                        numeric        `GLOBAL'
`max_connections'                           numeric        `GLOBAL'
`max_delayed_threads'                       numeric        `GLOBAL' |
                                                           `SESSION'
`max_error_count'                           numeric        `GLOBAL' |
                                                           `SESSION'
`max_heap_table_size'                       numeric        `GLOBAL' |
                                                           `SESSION'
`max_insert_delayed_threads'                numeric        `GLOBAL' |
                                                           `SESSION'
`max_join_size'                             numeric        `GLOBAL' |
                                                           `SESSION'
`max_length_for_sort_data'                  numeric        `GLOBAL' |
                                                           `SESSION'
`max_prepared_stmt_count'                   numeric        `GLOBAL'
`max_relay_log_size'                        numeric        `GLOBAL'
`max_seeks_for_key'                         numeric        `GLOBAL' |
                                                           `SESSION'
`max_sort_length'                           numeric        `GLOBAL' |
                                                           `SESSION'
`max_sp_recursion_depth'                    numeric        `GLOBAL' |
                                                           `SESSION'
`max_tmp_tables'                            numeric        `GLOBAL' |
                                                           `SESSION'
`max_user_connections'                      numeric        `GLOBAL' |
                                                           `SESSION'
`max_write_lock_count'                      numeric        `GLOBAL'
`min_examined_row_limit'                    numeric        `GLOBAL' |
                                                           `SESSION'
`multi_range_count'                         numeric        `GLOBAL' |
                                                           `SESSION'
`myisam_block_size'                         numeric        `GLOBAL' |
                                                           `SESSION'
`myisam_data_pointer_size'                  numeric        `GLOBAL'
`myisam_max_sort_file_size'                 numeric        `GLOBAL'
`myisam_repair_threads'                     numeric        `GLOBAL' |
                                                           `SESSION'
`myisam_sort_buffer_size'                   numeric        `GLOBAL' |
                                                           `SESSION'
`myisam_stats_method'                       enumeration    `GLOBAL' |
                                                           `SESSION'
`myisam_use_mmap'                           boolean        `GLOBAL'
`ndb_autoincrement_prefetch_sz'             numeric        `GLOBAL' |
                                                           `SESSION'
`ndb_cache_check_time'                      numeric        `GLOBAL'
`ndbcluster'                                boolean        `GLOBAL' |
                                                           `SESSION'
`ndb_extra_logging'                         numeric        `GLOBAL'
`ndb_force_send'                            boolean        `GLOBAL' |
                                                           `SESSION'
`ndb_log_update_as_write'                   boolean        `GLOBAL'
`ndb_log_updated_only'                      boolean        `GLOBAL'
`ndb_optimization_delay'                    numeric        `GLOBAL'
`ndb_table_no_logging'                      boolean        `SESSION'
`ndb_table_temporary'                       boolean        `SESSION'
`ndb_use_exact_count'                       boolean        `GLOBAL' |
                                                           `SESSION'
`net_buffer_length'                         numeric        `GLOBAL' |
                                                           `SESSION'
`net_read_timeout'                          numeric        `GLOBAL' |
                                                           `SESSION'
`net_retry_count'                           numeric        `GLOBAL' |
                                                           `SESSION'
`net_write_timeout'                         numeric        `GLOBAL' |
                                                           `SESSION'
`new'                                       boolean        `GLOBAL' |
                                                           `SESSION'
`old_passwords'                             boolean        `GLOBAL' |
                                                           `SESSION'
`optimizer_prune_level'                     boolean        `GLOBAL' |
                                                           `SESSION'
`optimizer_search_depth'                    numeric        `GLOBAL' |
                                                           `SESSION'
`plugin_innodb_autoextend_increment'        numeric        `GLOBAL' |
                                                           `SESSION'
`plugin_innodb_checksums'                   boolean        `GLOBAL' |
                                                           `SESSION'
`plugin_innodb_commit_concurrency'          numeric        `GLOBAL'
`plugin_innodb_concurrency_tickets'         numeric        `GLOBAL'
`plugin_innodb_flush_log_at_trx_commit'     numeric        `GLOBAL'
`plugin_innodb_max_dirty_pages_pct'         numeric        `GLOBAL'
`plugin_innodb_max_purge_lag'               numeric        `GLOBAL'
`plugin_innodb_support_xa'                  boolean        `GLOBAL' |
                                                           `SESSION'
`plugin_innodb_sync_spin_loops'             numeric        `GLOBAL'
`plugin_innodb_table_locks'                 boolean        `GLOBAL' |
                                                           `SESSION'
`plugin_innodb_thread_concurrency'          numeric        `GLOBAL'
`plugin_innodb_thread_sleep_delay'          numeric        `GLOBAL'
`preload_buffer_size'                       numeric        `GLOBAL' |
                                                           `SESSION'
`query_alloc_block_size'                    numeric        `GLOBAL' |
                                                           `SESSION'
`query_cache_limit'                         numeric        `GLOBAL'
`query_cache_min_res_unit'                  numeric        `GLOBAL'
`query_cache_size'                          numeric        `GLOBAL'
`query_cache_type'                          enumeration    `GLOBAL' |
                                                           `SESSION'
`query_cache_wlock_invalidate'              boolean        `GLOBAL' |
                                                           `SESSION'
`query_prealloc_size'                       numeric        `GLOBAL' |
                                                           `SESSION'
`range_alloc_block_size'                    numeric        `GLOBAL' |
                                                           `SESSION'
`read_buffer_size'                          numeric        `GLOBAL' |
                                                           `SESSION'
`read_only'                                 numeric        `GLOBAL'
`read_rnd_buffer_size'                      numeric        `GLOBAL' |
                                                           `SESSION'
`relay_log_purge'                           boolean        `GLOBAL'
*Note `rpl_recovery_rank':                  numeric        `GLOBAL'
replication-options.                                       
`secure_auth'                               boolean        `GLOBAL'
`server_id'                                 numeric        `GLOBAL'
*Note `slave_allow_batching':               boolean        `GLOBAL'
mysql-cluster-replication-starting.                        
`slave_compressed_protocol'                 boolean        `GLOBAL'
`slave_exec_mode'                           enumeration    `GLOBAL'
*Note `slave_net_timeout':                  numeric        `GLOBAL'
replication-options.                                       
`slave_transaction_retries'                 numeric        `GLOBAL'
`slow_launch_time'                          numeric        `GLOBAL'
`slow_query_log'                            boolean        `GLOBAL'
`slow_query_log_file'                       filename       `GLOBAL'
`sort_buffer_size'                          numeric        `GLOBAL' |
                                                           `SESSION'
`sql_auto_is_null'                          boolean        `SESSION'
`sql_big_selects'                           boolean        `SESSION'
`sql_big_tables'                            boolean        `SESSION'
`sql_buffer_result'                         boolean        `SESSION'
`sql_log_bin'                               boolean        `SESSION'
`sql_log_off'                               boolean        `SESSION'
`sql_log_update'                            boolean        `SESSION'
`sql_low_priority_updates'                  boolean        `GLOBAL' |
                                                           `SESSION'
`sql_max_join_size'                         numeric        `GLOBAL' |
                                                           `SESSION'
`sql_mode'                                  enumeration    `GLOBAL' |
                                                           `SESSION'
`sql_notes'                                 boolean        `SESSION'
`sql_quote_show_create'                     boolean        `SESSION'
`sql_safe_updates'                          boolean        `SESSION'
`sql_select_limit'                          numeric        `GLOBAL' |
                                                           `SESSION'
`sql_slave_skip_counter'                    numeric        `GLOBAL'
`sql_warnings'                              boolean        `SESSION'
`storage_engine'                            enumeration    `GLOBAL' |
                                                           `SESSION'
`sync_binlog'                               numeric        `GLOBAL'
`sync_frm'                                  boolean        `GLOBAL'
`table_cache'                               numeric        `GLOBAL'
`table_definition_cache'                    numeric        `GLOBAL'
`table_lock_wait_timeout'                   numeric        `GLOBAL'
`table_open_cache'                          numeric        `GLOBAL'
`table_type'                                enumeration    `GLOBAL' |
                                                           `SESSION'
`thread_cache_size'                         numeric        `GLOBAL'
`timed_mutexes'                             boolean        `GLOBAL'
`time_format'                               string         `GLOBAL' |
                                                           `SESSION'
`timestamp'                                 string         `SESSION'
`time_zone'                                 string         `GLOBAL' |
                                                           `SESSION'
`tmp_table_size'                            numeric        `GLOBAL' |
                                                           `SESSION'
`transaction_alloc_block_size'              numeric        `GLOBAL' |
                                                           `SESSION'
`transaction_allow_batching'                boolean        `SESSION'
`transaction_prealloc_size'                 numeric        `GLOBAL' |
                                                           `SESSION'
`tx_isolation'                              enumeration    `GLOBAL' |
                                                           `SESSION'
`unique_checks'                             boolean        `SESSION'
`updatable_views_with_limit'                boolean        `GLOBAL' |
                                                           `SESSION'
`wait_timeout'                              numeric        `GLOBAL' |
                                                           `SESSION'

MySQL Enterprise

Improper configuration of system variables can adversely affect
performance and security. The MySQL Enterprise Monitor continually
monitors system variables and provides expert advice about appropriate
settings. For more information see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: server-status-variables,  Next: server-sql-mode,  Prev: using-system-variables,  Up: mysqld-server

5.1.6 Status Variables
----------------------

The server maintains many status variables that provide information
about its operation. You can view these variables and their values by
using the `SHOW [GLOBAL | SESSION] STATUS' statement (see *Note
show-status::).  The optional `GLOBAL' keyword aggregates the values
over all connections, and `SESSION' shows the values for the current
connection.

     mysql> SHOW GLOBAL STATUS;
     +-----------------------------------+------------+
     | Variable_name                     | Value      |
     +-----------------------------------+------------+
     | Aborted_clients                   | 0          |
     | Aborted_connects                  | 0          |
     | Bytes_received                    | 155372598  |
     | Bytes_sent                        | 1176560426 |
     ...
     | Connections                       | 30023      |
     | Created_tmp_disk_tables           | 0          |
     | Created_tmp_files                 | 3          |
     | Created_tmp_tables                | 2          |
     ...
     | Threads_created                   | 217        |
     | Threads_running                   | 88         |
     | Uptime                            | 1389872    |
     +-----------------------------------+------------+

The following table lists all available server status variables:

*Variable Name*                             *Variable      *Variable
                                            Type*          Scope*
`Aborted_clients'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Aborted_connects'                          numeric        `GLOBAL'
`Binlog_cache_disk_use'                     numeric        `GLOBAL' |
                                                           `SESSION'
`Binlog_cache_use'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Bytes_received'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Bytes_sent'                                numeric        `GLOBAL' |
                                                           `SESSION'
`Com_admin_commands'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Com_alter_db'                              numeric        `GLOBAL' |
                                                           `SESSION'
`Com_alter_event'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_alter_table'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_analyze'                               numeric        `GLOBAL' |
                                                           `SESSION'
`Com_backup_table'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_begin'                                 numeric        `GLOBAL' |
                                                           `SESSION'
`Com_call_procedure'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Com_change_db'                             numeric        `GLOBAL' |
                                                           `SESSION'
`Com_change_master'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Com_check'                                 numeric        `GLOBAL' |
                                                           `SESSION'
`Com_checksum'                              numeric        `GLOBAL' |
                                                           `SESSION'
`Com_commit'                                numeric        `GLOBAL' |
                                                           `SESSION'
`Com_create_db'                             numeric        `GLOBAL' |
                                                           `SESSION'
`Com_create_event'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_create_function'                       numeric        `GLOBAL' |
                                                           `SESSION'
`Com_create_index'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_create_table'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_create_user'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_dealloc_sql'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_delete'                                numeric        `GLOBAL' |
                                                           `SESSION'
`Com_delete_multi'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_do'                                    numeric        `GLOBAL' |
                                                           `SESSION'
`Com_drop_db'                               numeric        `GLOBAL' |
                                                           `SESSION'
`Com_drop_event'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Com_drop_function'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Com_drop_index'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Com_drop_table'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Com_drop_user'                             numeric        `GLOBAL' |
                                                           `SESSION'
`Com_execute_sql'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_flush'                                 numeric        `GLOBAL' |
                                                           `SESSION'
`Com_grant'                                 numeric        `GLOBAL' |
                                                           `SESSION'
`Com_ha_close'                              numeric        `GLOBAL' |
                                                           `SESSION'
`Com_ha_open'                               numeric        `GLOBAL' |
                                                           `SESSION'
`Com_ha_read'                               numeric        `GLOBAL' |
                                                           `SESSION'
`Com_help'                                  numeric        `GLOBAL' |
                                                           `SESSION'
`Com_insert'                                numeric        `GLOBAL' |
                                                           `SESSION'
`Com_insert_select'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Com_kill'                                  numeric        `GLOBAL' |
                                                           `SESSION'
`Com_load'                                  numeric        `GLOBAL' |
                                                           `SESSION'
`Com_lock_tables'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_optimize'                              numeric        `GLOBAL' |
                                                           `SESSION'
`Com_preload_keys'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_prepare_sql'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Compression'                               numeric        `GLOBAL' |
                                                           `SESSION'
`Com_purge'                                 numeric        `GLOBAL' |
                                                           `SESSION'
`Com_purge_before_date'                     numeric        `GLOBAL' |
                                                           `SESSION'
`Com_rename_table'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_repair'                                numeric        `GLOBAL' |
                                                           `SESSION'
`Com_replace'                               numeric        `GLOBAL' |
                                                           `SESSION'
`Com_replace_select'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Com_reset'                                 numeric        `GLOBAL' |
                                                           `SESSION'
`Com_restore_table'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Com_revoke'                                numeric        `GLOBAL' |
                                                           `SESSION'
`Com_revoke_all'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Com_rollback'                              numeric        `GLOBAL' |
                                                           `SESSION'
`Com_savepoint'                             numeric        `GLOBAL' |
                                                           `SESSION'
`Com_select'                                numeric        `GLOBAL' |
                                                           `SESSION'
`Com_set_option'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_binlog_events'                    numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_binlogs'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_charsets'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_collations'                       numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_column_types'                     numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_create_db'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_create_event'                     numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_create_table'                     numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_databases'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_engine_logs'                      numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_engine_mutex'                     numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_engine_status'                    numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_errors'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_events'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_fields'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_grants'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_innodb_status'                    numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_keys'                             numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_logs'                             numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_master_status'                    numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_ndb_status'                       numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_new_master'                       numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_open_tables'                      numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_plugins'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_privileges'                       numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_processlist'                      numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_slave_hosts'                      numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_slave_status'                     numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_status'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_storage_engines'                  numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_tables'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_triggers'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_variables'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Com_show_warnings'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Com_slave_start'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_slave_stop'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Com_stmt_close'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Com_stmt_execute'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_stmt_fetch'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Com_stmt_prepare'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_stmt_reprepare'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Com_stmt_reset'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Com_stmt_send_long_data'                   numeric        `GLOBAL' |
                                                           `SESSION'
`Com_truncate'                              numeric        `GLOBAL' |
                                                           `SESSION'
`Com_unlock_tables'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Com_update'                                numeric        `GLOBAL' |
                                                           `SESSION'
`Com_update_multi'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Com_xa_commit'                             numeric        `GLOBAL' |
                                                           `SESSION'
`Com_xa_end'                                numeric        `GLOBAL' |
                                                           `SESSION'
`Com_xa_prepare'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Com_xa_recover'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Com_xa_rollback'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Com_xa_start'                              numeric        `GLOBAL' |
                                                           `SESSION'
`Connections'                               numeric        `GLOBAL' |
                                                           `SESSION'
`Created_tmp_disk_tables'                   numeric        `GLOBAL' |
                                                           `SESSION'
`Created_tmp_files'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Created_tmp_tables'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Delayed_errors'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Delayed_insert_threads'                    numeric        `GLOBAL' |
                                                           `SESSION'
`Delayed_writes'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Flush_commands'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_commit'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_delete'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_discover'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_prepare'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_read_first'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_read_key'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_read_next'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_read_prev'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_read_rnd'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_read_rnd_next'                     numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_rollback'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_savepoint'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_savepoint_rollback'                numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_update'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Handler_write'                             numeric        `GLOBAL' |
                                                           `SESSION'
`Innodb_buffer_pool_pages_data'             numeric        `GLOBAL'
`Innodb_buffer_pool_pages_dirty'            numeric        `GLOBAL'
`Innodb_buffer_pool_pages_flushed'          numeric        `GLOBAL'
`Innodb_buffer_pool_pages_free'             numeric        `GLOBAL'
`Innodb_buffer_pool_pages_latched'          numeric        `GLOBAL'
`Innodb_buffer_pool_pages_misc'             numeric        `GLOBAL'
`Innodb_buffer_pool_pages_total'            numeric        `GLOBAL'
`Innodb_buffer_pool_read_ahead_rnd'         numeric        `GLOBAL'
`Innodb_buffer_pool_read_ahead_seq'         numeric        `GLOBAL'
`Innodb_buffer_pool_read_requests'          numeric        `GLOBAL'
`Innodb_buffer_pool_reads'                  numeric        `GLOBAL'
`Innodb_buffer_pool_wait_free'              numeric        `GLOBAL'
`Innodb_buffer_pool_write_requests'         numeric        `GLOBAL'
`Innodb_data_fsyncs'                        numeric        `GLOBAL'
`Innodb_data_pending_fsyncs'                numeric        `GLOBAL'
`Innodb_data_pending_reads'                 numeric        `GLOBAL'
`Innodb_data_pending_writes'                numeric        `GLOBAL'
`Innodb_data_read'                          numeric        `GLOBAL'
`Innodb_data_reads'                         numeric        `GLOBAL'
`Innodb_data_writes'                        numeric        `GLOBAL'
`Innodb_data_written'                       numeric        `GLOBAL'
`Innodb_dblwr_pages_written'                numeric        `GLOBAL'
`Innodb_dblwr_writes'                       numeric        `GLOBAL'
`Innodb_log_waits'                          numeric        `GLOBAL'
`Innodb_log_write_requests'                 numeric        `GLOBAL'
`Innodb_log_writes'                         numeric        `GLOBAL'
`Innodb_os_log_fsyncs'                      numeric        `GLOBAL'
`Innodb_os_log_pending_fsyncs'              numeric        `GLOBAL'
`Innodb_os_log_pending_writes'              numeric        `GLOBAL'
`Innodb_os_log_written'                     numeric        `GLOBAL'
`Innodb_pages_created'                      numeric        `GLOBAL'
`Innodb_page_size'                          numeric        `GLOBAL'
`Innodb_pages_read'                         numeric        `GLOBAL'
`Innodb_pages_written'                      numeric        `GLOBAL'
`Innodb_row_lock_current_waits'             numeric        `GLOBAL'
`Innodb_row_lock_time'                      numeric        `GLOBAL'
`Innodb_row_lock_time_avg'                  numeric        `GLOBAL'
`Innodb_row_lock_time_max'                  numeric        `GLOBAL'
`Innodb_row_lock_waits'                     numeric        `GLOBAL'
`Innodb_rows_deleted'                       numeric        `GLOBAL'
`Innodb_rows_inserted'                      numeric        `GLOBAL'
`Innodb_rows_read'                          numeric        `GLOBAL'
`Innodb_rows_updated'                       numeric        `GLOBAL'
`Key_blocks_not_flushed'                    numeric        `GLOBAL' |
                                                           `SESSION'
`Key_blocks_unused'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Key_blocks_used'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Key_read_requests'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Key_reads'                                 numeric        `GLOBAL' |
                                                           `SESSION'
`Key_write_requests'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Key_writes'                                numeric        `GLOBAL' |
                                                           `SESSION'
`Last_query_cost'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Max_used_connections'                      numeric        `GLOBAL' |
                                                           `SESSION'
`ndb-cluster-connection-pool'               numeric        `GLOBAL'
`Ndb_cluster_node_id'                       numeric        `GLOBAL' |
                                                           `SESSION'
`Ndb_config_from_host'                      numeric        `GLOBAL' |
                                                           `SESSION'
`Ndb_config_from_port'                      numeric        `GLOBAL' |
                                                           `SESSION'
`Ndb_conflict_fn_max'                       numeric        `GLOBAL' |
                                                           `SESSION'
`Ndb_conflict_fn_old'                       numeric        `GLOBAL' |
                                                           `SESSION'
`ndb_execute_count'                         numeric        `GLOBAL'
`Ndb_number_of_data_nodes'                  numeric        `GLOBAL' |
                                                           `SESSION'
`Not_flushed_delayed_rows'                  numeric        `GLOBAL' |
                                                           `SESSION'
`Opened_files'                              numeric        `GLOBAL'
`Opened_tables'                             numeric        `GLOBAL' |
                                                           `SESSION'
`Open_files'                                numeric        `GLOBAL' |
                                                           `SESSION'
`Open_streams'                              numeric        `GLOBAL' |
                                                           `SESSION'
`Open_table_definitions'                    numeric        `GLOBAL' |
                                                           `SESSION'
`Open_tables'                               numeric        `GLOBAL' |
                                                           `SESSION'
`prepared_stmt_count'                       numeric        `GLOBAL'
`Qcache_free_blocks'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Qcache_free_memory'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Qcache_hits'                               numeric        `GLOBAL' |
                                                           `SESSION'
`Qcache_inserts'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Qcache_lowmem_prunes'                      numeric        `GLOBAL' |
                                                           `SESSION'
`Qcache_not_cached'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Qcache_queries_in_cache'                   numeric        `GLOBAL' |
                                                           `SESSION'
`Qcache_total_blocks'                       numeric        `GLOBAL' |
                                                           `SESSION'
`Questions'                                 numeric        `GLOBAL' |
                                                           `SESSION'
`Rpl_status'                                string         `GLOBAL' |
                                                           `SESSION'
`Select_full_join'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Select_full_range_join'                    numeric        `GLOBAL' |
                                                           `SESSION'
`Select_range'                              numeric        `GLOBAL' |
                                                           `SESSION'
`Select_range_check'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Select_scan'                               numeric        `GLOBAL' |
                                                           `SESSION'
`Slave_heartbeat_period'                                   `GLOBAL'
`Slave_open_temp_tables'                    numeric        `GLOBAL' |
                                                           `SESSION'
`Slave_received_heartbeats'                                `GLOBAL'
`Slave_retried_transactions'                numeric        `GLOBAL' |
                                                           `SESSION'
`Slave_running'                             boolean        `GLOBAL' |
                                                           `SESSION'
`Slow_launch_threads'                       numeric        `GLOBAL' |
                                                           `SESSION'
`Slow_queries'                              numeric        `GLOBAL' |
                                                           `SESSION'
`Sort_merge_passes'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Sort_range'                                numeric        `GLOBAL' |
                                                           `SESSION'
`Sort_rows'                                 numeric        `GLOBAL' |
                                                           `SESSION'
`Sort_scan'                                 numeric        `GLOBAL' |
                                                           `SESSION'
`Table_locks_immediate'                     numeric        `GLOBAL' |
                                                           `SESSION'
`Table_locks_waited'                        numeric        `GLOBAL' |
                                                           `SESSION'
`Tc_log_max_pages_used'                     numeric        `GLOBAL' |
                                                           `SESSION'
`Tc_log_page_size'                          numeric        `GLOBAL' |
                                                           `SESSION'
`Tc_log_page_waits'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Threads_cached'                            numeric        `GLOBAL' |
                                                           `SESSION'
`Threads_connected'                         numeric        `GLOBAL' |
                                                           `SESSION'
`Threads_created'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Threads_running'                           numeric        `GLOBAL' |
                                                           `SESSION'
`Uptime'                                    numeric        `GLOBAL' |
                                                           `SESSION'
`Uptime_since_flush_status'                 numeric        `GLOBAL' |
                                                           `SESSION'

Many status variables are reset to 0 by the `FLUSH STATUS' statement.

MySQL Enterprise

For expert advice on using status variables, subscribe to the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

The status variables have the following meanings. Variables with no
version indicated were already present prior to MySQL 5.1. For
information regarding their implementation history, see `MySQL 5.0
Reference Manual'.

   *  `Aborted_clients'

     The number of connections that were aborted because the client
     died without closing the connection properly. See *Note
     communication-errors::.

   *  `Aborted_connects'

     The number of failed attempts to connect to the MySQL server. See
     *Note communication-errors::.

   *  `Binlog_cache_disk_use'

     The number of transactions that used the temporary binary log
     cache but that exceeded the value of `binlog_cache_size' and used
     a temporary file to store statements from the transaction.

   *  `Binlog_cache_use'

     The number of transactions that used the temporary binary log
     cache.

   *  `Bytes_received'

     The number of bytes received from all clients.

   *  `Bytes_sent'

     The number of bytes sent to all clients.

   *  `Com_XXX'

     The `Com_XXX' statement counter variables indicate the number of
     times each XXX statement has been executed. There is one status
     variable for each type of statement. For example, `Com_delete' and
     `Com_insert' count `DELETE' and `INSERT' statements, respectively.
     However, if a query result is returned from query cache, the
     server increments the `Qcache_hits' status variable, not
     `Com_select'. See *Note query-cache-status-and-maintenance::.

     All of the `Com_stmt_XXX' variables are increased even if a
     prepared statement argument is unknown or an error occurred during
     execution.  In other words, their values correspond to the number
     of requests issued, not to the number of requests successfully
     completed.

     The `Com_stmt_XXX' status variables are as follows:

        * `Com_stmt_prepare'

        * `Com_stmt_execute'

        * `Com_stmt_fetch'

        * `Com_stmt_send_long_data'

        * `Com_stmt_reset'

        * `Com_stmt_close'

     Those variables stand for prepared statement commands. Their names
     refer to the `COM_XXX' command set used in the network layer. In
     other words, their values increase whenever prepared statement API
     calls such as `mysql_stmt_prepare()', `mysql_stmt_execute()', and
     so forth are executed. However, `Com_stmt_prepare',
     `Com_stmt_execute' and `Com_stmt_close' also increase for
     `PREPARE', `EXECUTE', or `DEALLOCATE PREPARE', respectively.
     Additionally, the values of the older (available since MySQL
     4.1.3) statement counter variables `Com_prepare_sql',
     `Com_execute_sql', and `Com_dealloc_sql' increase for the
     `PREPARE', `EXECUTE', and `DEALLOCATE PREPARE' statements.
     `Com_stmt_fetch' stands for the total number of network
     round-trips issued when fetching from cursors.

     `Com_stmt_reprepare' indicated the number of times statements were
     automatically reprepared by the server after metadata changes to
     tables or views referred to by the statement. This variable was
     added in MySQL 5.1.25. A reprepare operation increments
     `Com_stmt_reprepare' is incremented, and also `Com_stmt_prepare'.

   *  `Compression'

     Whether the client connection uses compression in the
     client/server protocol. Added in MySQL 5.1.2.

   *  `Connections'

     The number of connection attempts (successful or not) to the MySQL
     server.

   *  `Created_tmp_disk_tables'

     The number of temporary tables on disk created automatically by
     the server while executing statements.

   *  `Created_tmp_files'

     How many temporary files `mysqld' has created.

   *  `Created_tmp_tables'

     The number of in-memory temporary tables created automatically by
     the server while executing statements. If
     `Created_tmp_disk_tables' is large, you may want to increase the
     `tmp_table_size' value to cause temporary tables to be
     memory-based instead of disk-based.

   *  `Delayed_errors'

     The number of rows written with `INSERT DELAYED' for which some
     error occurred (probably `duplicate key').

   *  `Delayed_insert_threads'

     The number of `INSERT DELAYED' handler threads in use.

   *  `Delayed_writes'

     The number of `INSERT DELAYED' rows written.

   *  `Flush_commands'

     The number of executed `FLUSH' statements.

   *  `Handler_commit'

     The number of internal `COMMIT' statements.

   *  `Handler_delete'

     The number of times that rows have been deleted from tables.

   *  `Handler_prepare'

     A counter for the prepare phase of two-phase commit operations.

   *  `Handler_read_first'

     The number of times the first entry was read from an index.  If
     this value is high, it suggests that the server is doing a lot of
     full index scans; for example, `SELECT col1 FROM foo', assuming
     that `col1' is indexed.

   *  `Handler_read_key'

     The number of requests to read a row based on a key. If this value
     is high, it is a good indication that your tables are properly
     indexed for your queries.

   *  `Handler_read_next'

     The number of requests to read the next row in key order.  This
     value is incremented if you are querying an index column with a
     range constraint or if you are doing an index scan.

   *  `Handler_read_prev'

     The number of requests to read the previous row in key order. This
     read method is mainly used to optimize `ORDER BY ... DESC'.

   *  `Handler_read_rnd'

     The number of requests to read a row based on a fixed position.
     This value is high if you are doing a lot of queries that require
     sorting of the result. You probably have a lot of queries that
     require MySQL to scan entire tables or you have joins that don't
     use keys properly.

   *  `Handler_read_rnd_next'

     The number of requests to read the next row in the data file. This
     value is high if you are doing a lot of table scans. Generally
     this suggests that your tables are not properly indexed or that
     your queries are not written to take advantage of the indexes you
     have.

   *  `Handler_rollback'

     The number of requests for a storage engine to perform a rollback
     operation.

   *  `Handler_savepoint'

     The number of requests for a storage engine to place a savepoint.

   *  `Handler_savepoint_rollback'

     The number of requests for a storage engine to roll back to a
     savepoint.

   *  `Handler_update'

     The number of requests to update a row in a table.

   *  `Handler_write'

     The number of requests to insert a row in a table.

   *  `Innodb_buffer_pool_pages_data'

     The number of pages containing data (dirty or clean).

   *  `Innodb_buffer_pool_pages_dirty'

     The number of pages currently dirty.

   *  `Innodb_buffer_pool_pages_flushed'

     The number of buffer pool page-flush requests.

   *  `Innodb_buffer_pool_pages_free'

     The number of free pages.

   *  `Innodb_buffer_pool_pages_latched'

     The number of latched pages in `InnoDB' buffer pool. These are
     pages currently being read or written or that cannot be flushed or
     removed for some other reason.

   *  `Innodb_buffer_pool_pages_misc'

     The number of pages that are busy because they have been allocated
     for administrative overhead such as row locks or the adaptive hash
     index. This value can also be calculated as
     `Innodb_buffer_pool_pages_total' - `Innodb_buffer_pool_pages_free'
     - `Innodb_buffer_pool_pages_data'.

   *  `Innodb_buffer_pool_pages_total'

     The total size of the buffer pool, in pages.

   *  `Innodb_buffer_pool_read_ahead_rnd'

     The number of `random' read-aheads initiated by `InnoDB'. This
     happens when a query scans a large portion of a table but in
     random order.

   *  `Innodb_buffer_pool_read_ahead_seq'

     The number of sequential read-aheads initiated by `InnoDB'. This
     happens when `InnoDB' does a sequential full table scan.

   *  `Innodb_buffer_pool_read_requests'

     The number of logical read requests `InnoDB' has done.

   *  `Innodb_buffer_pool_reads'

     The number of logical reads that `InnoDB' could not satisfy from
     the buffer pool and had to do a single-page read.

   *  `Innodb_buffer_pool_wait_free'

     Normally, writes to the `InnoDB' buffer pool happen in the
     background. However, if it is necessary to read or create a page
     and no clean pages are available, it is also necessary to wait for
     pages to be flushed first.  This counter counts instances of these
     waits. If the buffer pool size has been set properly, this value
     should be small.

   *  `Innodb_buffer_pool_write_requests'

     The number writes done to the `InnoDB' buffer pool.

   *  `Innodb_data_fsyncs'

     The number of `fsync()' operations so far.

   *  `Innodb_data_pending_fsyncs'

     The current number of pending `fsync()' operations.

   *  `Innodb_data_pending_reads'

     The current number of pending reads.

   *  `Innodb_data_pending_writes'

     The current number of pending writes.

   *  `Innodb_data_read'

     The amount of data read so far, in bytes.

   *  `Innodb_data_reads'

     The total number of data reads.

   *  `Innodb_data_writes'

     The total number of data writes.

   *  `Innodb_data_written'

     The amount of data written so far, in bytes.

   *  `Innodb_dblwr_writes'

     The number of doublewrite operations that have been performed. See
     *Note innodb-disk-io::.

   *  `Innodb_dblwr_pages_written'

     The number of pages that have been written for doublewrite
     operations. See *Note innodb-disk-io::.

   *  `Innodb_log_waits'

     The number of times that the log buffer was too small and a wait
     was required for it to be flushed before continuing.

   *  `Innodb_log_write_requests'

     The number of log write requests.

   *  `Innodb_log_writes'

     The number of physical writes to the log file.

   *  `Innodb_os_log_fsyncs'

     The number of `fsync()' writes done to the log file.

   *  `Innodb_os_log_pending_fsyncs'

     The number of pending log file `fsync()' operations.

   *  `Innodb_os_log_pending_writes'

     The number of pending log file writes.

   *  `Innodb_os_log_written'

     The number of bytes written to the log file.

   *  `Innodb_page_size'

     The compiled-in `InnoDB' page size (default 16KB). Many values are
     counted in pages; the page size allows them to be easily converted
     to bytes.

   *  `Innodb_pages_created'

     The number of pages created.

   *  `Innodb_pages_read'

     The number of pages read.

   *  `Innodb_pages_written'

     The number of pages written.

   *  `Innodb_row_lock_current_waits'

     The number of row locks currently being waited for.

   *  `Innodb_row_lock_time'

     The total time spent in acquiring row locks, in milliseconds.

   *  `Innodb_row_lock_time_avg'

     The average time to acquire a row lock, in milliseconds.

   *  `Innodb_row_lock_time_max'

     The maximum time to acquire a row lock, in milliseconds.

   *  `Innodb_row_lock_waits'

     The number of times a row lock had to be waited for.

   *  `Innodb_rows_deleted'

     The number of rows deleted from `InnoDB' tables.

   *  `Innodb_rows_inserted'

     The number of rows inserted into `InnoDB' tables.

   *  `Innodb_rows_read'

     The number of rows read from `InnoDB' tables.

   *  `Innodb_rows_updated'

     The number of rows updated in `InnoDB' tables.

   *  `Key_blocks_not_flushed'

     The number of key blocks in the key cache that have changed but
     have not yet been flushed to disk.

   *  `Key_blocks_unused'

     The number of unused blocks in the key cache. You can use this
     value to determine how much of the key cache is in use; see the
     discussion of `key_buffer_size' in *Note server-system-variables::.

   *  `Key_blocks_used'

     The number of used blocks in the key cache. This value is a
     high-water mark that indicates the maximum number of blocks that
     have ever been in use at one time.

   *  `Key_read_requests'

     The number of requests to read a key block from the cache.

   *  `Key_reads'

     The number of physical reads of a key block from disk. If
     `Key_reads' is large, then your `key_buffer_size' value is
     probably too small. The cache miss rate can be calculated as
     `Key_reads'/`Key_read_requests'.

   *  `Key_write_requests'

     The number of requests to write a key block to the cache.

   *  `Key_writes'

     The number of physical writes of a key block to disk.

   *  `Last_query_cost'

     The total cost of the last compiled query as computed by the query
     optimizer. This is useful for comparing the cost of different
     query plans for the same query. The default value of 0 means that
     no query has been compiled yet. The default value is 0.
     `Last_query_cost' has session scope.

     The `Last_query_cost' value can be computed accurately only for
     simple `flat' queries, not complex queries such as those with
     subqueries or `UNION'. For the latter, the value is set to 0.

   *  `Max_used_connections'

     The maximum number of connections that have been in use
     simultaneously since the server started.

   *  `Not_flushed_delayed_rows'

     The number of rows waiting to be written in `INSERT DELAY' queues.

   *  `Open_files'

     The number of files that are open.

   *  `Open_streams'

     The number of streams that are open (used mainly for logging).

   *  `Open_table_definitions'

     The number of cached `.frm' files. This variable was added in
     MySQL 5.1.3.

   *  `Open_tables'

     The number of tables that are open.

   *  `Opened_files'

     The number of files that have been opened with `my_open()' (a
     `mysys' library function). Parts of the server that open files
     without using this function do not increment the count. This
     variable was added in MySQL 5.1.21.

   *  `Opened_tables'

     The number of tables that have been opened. If `Opened_tables' is
     big, your `table_open_cache' value is probably too small.

   *  `Prepared_stmt_count'

     The current number of prepared statements. (The maximum number of
     statements is given by the `max_prepared_stmt_count' system
     variable.)  This variable was added in MySQL 5.1.14.

   *  `Qcache_free_blocks'

     The number of free memory blocks in the query cache.

   *  `Qcache_free_memory'

     The amount of free memory for the query cache.

   *  `Qcache_hits'

     The number of query cache hits.

   *  `Qcache_inserts'

     The number of queries added to the query cache.

   *  `Qcache_lowmem_prunes'

     The number of queries that were deleted from the query cache
     because of low memory.

   *  `Qcache_not_cached'

     The number of non-cached queries (not cacheable, or not cached due
     to the `query_cache_type' setting).

   *  `Qcache_queries_in_cache'

     The number of queries registered in the query cache.

   *  `Qcache_total_blocks'

     The total number of blocks in the query cache.

   *  `Questions'

     The number of statements that clients have sent to the server.

   *  `Rpl_status'

     The status of fail-safe replication (not yet implemented).

   *  `Select_full_join'

     The number of joins that perform table scans because they do not
     use indexes. If this value is not 0, you should carefully check
     the indexes of your tables.

   *  `Select_full_range_join'

     The number of joins that used a range search on a reference table.

   *  `Select_range'

     The number of joins that used ranges on the first table.

     This is normally not a critical issue even if the value is quite
     large.

   *  `Select_range_check'

     The number of joins without keys that check for key usage after
     each row. If this is not 0, you should carefully check the indexes
     of your tables.

   *  `Select_scan'

     The number of joins that did a full scan of the first table.

   *  `Slave_open_temp_tables'

     The number of temporary tables that the slave SQL thread currently
     has open.

   *  `Slave_retried_transactions'

     The total number of times since startup that the replication slave
     SQL thread has retried transactions.

   *  `Slave_running'

     This is `ON' if this server is a slave that is connected to a
     master, and both the I/O SQL and threads are running.

   *  `Slow_launch_threads'

     The number of threads that have taken more than `slow_launch_time'
     seconds to create.

   *  `Slow_queries'

     The number of queries that have taken more than `long_query_time'
     seconds. See *Note slow-query-log::.

   *  `Sort_merge_passes'

     The number of merge passes that the sort algorithm has had to do.
     If this value is large, you should consider increasing the value
     of the `sort_buffer_size' system variable.

   *  `Sort_range'

     The number of sorts that were done using ranges.

   *  `Sort_rows'

     The number of sorted rows.

   *  `Sort_scan'

     The number of sorts that were done by scanning the table.

   *  `Ssl_XXX'

     Variables used for SSL connections.

   *  `Table_locks_immediate'

     The number of times that a request for a table lock could be
     granted immediately.

   *  `Table_locks_waited'

     The number of times that a request for a table lock could not be
     granted immediately and a wait was needed. If this is high and you
     have performance problems, you should first optimize your queries,
     and then either split your table or tables or use replication.

   *  `Tc_log_max_pages_used'

     For the memory-mapped implementation of the log that is used by
     `mysqld' when it acts as the transaction coordinator for recovery
     of internal XA transactions, this variable indicates the largest
     number of pages used for the log since the server started. If the
     product of `Tc_log_max_pages_used' and `Tc_log_page_size' is
     always significantly less than the log size, the size is larger
     than necessary and can be reduced. (The size is set by the
     `--log-tc-size' option. Currently, this variable is unused: It is
     unneeded for binary log-based recovery, and the memory-mapped
     recovery log method is not used unless the number of storage
     engines capable of two-phase commit is greater than one.
     (`InnoDB' is the only applicable engine.)

   *  `Tc_log_page_size'

     The page size used for the memory-mapped implementation of the XA
     recovery log. The default value is determined using
     `getpagesize()'. Currently, this variable is unused for the same
     reasons as described for `Tc_log_max_pages_used'.

   *  `Tc_log_page_waits'

     For the memory-mapped implementation of the recovery log, this
     variable increments each time the server was not able to commit a
     transaction and had to wait for a free page in the log. If this
     value is large, you might want to increase the log size (with the
     `--log-tc-size' option). For binary log-based recovery, this
     variable increments each time the binary log cannot be closed
     because there are two-phase commits in progress. (The close
     operation waits until all such transactions are finished.)

   *  `Threads_cached'

     The number of threads in the thread cache.

   *  `Threads_connected'

     The number of currently open connections.

   *  `Threads_created'

     The number of threads created to handle connections. If
     `Threads_created' is big, you may want to increase the
     `thread_cache_size' value. The cache miss rate can be calculated as
     `Threads_created'/`Connections'.

   *  `Threads_running'

     The number of threads that are not sleeping.

   *  `Uptime'

     The number of seconds that the server has been up.


File: manual.info,  Node: server-sql-mode,  Next: server-side-help-support,  Prev: server-status-variables,  Up: mysqld-server

5.1.7 SQL Modes
---------------

The MySQL server can operate in different SQL modes, and can apply
these modes differently for different clients. This capability enables
each application to tailor the server's operating mode to its own
requirements.

For answers to some questions that are often asked about server SQL
modes in MySQL, see *Note faqs-sql-modes::.

Modes define what SQL syntax MySQL should support and what kind of data
validation checks it should perform. This makes it easier to use MySQL
in different environments and to use MySQL together with other database
servers.

You can set the default SQL mode by starting `mysqld' with the
`--sql-mode="MODES"' option, or by using `sql-mode="MODES"' in `my.cnf'
(Unix operating systems) or `my.ini' (Windows).  MODES is a list of
different modes separated by comma (``,'') characters. The default
value is empty (no modes set). The MODES value also can be empty
(`--sql-mode=""' on the command line, or `sql-mode=""' in `my.cnf' on
Unix systems or in `my.ini' on Windows) if you want to clear it
explicitly.

You can change the SQL mode at runtime by using a `SET [GLOBAL|SESSION]
sql_mode='MODES'' statement to set the `sql_mode' system value. Setting
the `GLOBAL' variable requires the `SUPER' privilege and affects the
operation of all clients that connect from that time on. Setting the
`SESSION' variable affects only the current client. Any client can
change its own session `sql_mode' value at any time.

*Important*:

SQL mode and user-defined partitioning

Changing the server SQL mode after creating and inserting data into
partitioned tables can cause major changes in the behavior of such
tables, and could lead to loss or corruption of data. It is strongly
recommended that you never change the SQL mode once you have created
tables employing user-defined partitioning.

See *Note partitioning-limitations::, for more information.

You can retrieve the current global or session `sql_mode' value with
the following statements:

     SELECT @@global.sql_mode;
     SELECT @@session.sql_mode;

The most important `sql_mode' values are probably these:

   * `ANSI'

     This mode changes syntax and behavior to conform more closely to
     standard SQL.

   * `STRICT_TRANS_TABLES'

     If a value could not be inserted as given into a transactional
     table, abort the statement. For a non-transactional table, abort
     the statement if the value occurs in a single-row statement or the
     first row of a multiple-row statement. More detail is given later
     in this section.

   * `TRADITIONAL'

     Make MySQL behave like a `traditional' SQL database system. A
     simple description of this mode is `give an error instead of a
     warning' when inserting an incorrect value into a column.

     *Note*:

     The `INSERT'/`UPDATE' aborts as soon as the error is noticed. This
     may not be what you want if you are using a non-transactional
     storage engine, because data changes made prior to the error may
     not be rolled back, resulting in a `partially done' update.

When this manual refers to `strict mode,' it means a mode where at
least one of `STRICT_TRANS_TABLES' or `STRICT_ALL_TABLES' is enabled.

The following list describes all supported modes:

   * `ALLOW_INVALID_DATES'

     Don't do full checking of dates. Check only that the month is in
     the range from 1 to 12 and the day is in the range from 1 to 31.
     This is very convenient for Web applications where you obtain
     year, month, and day in three different fields and you want to
     store exactly what the user inserted (without date validation).
     This mode applies to `DATE' and `DATETIME' columns. It does not
     apply `TIMESTAMP' columns, which always require a valid date.

     The server requires that month and day values be legal, and not
     merely in the range 1 to 12 and 1 to 31, respectively.  With
     strict mode disabled, invalid dates such as `'2004-04-31'' are
     converted to `'0000-00-00'' and a warning is generated.  With
     strict mode enabled, invalid dates generate an error.  To allow
     such dates, enable `ALLOW_INVALID_DATES'.

   * `ANSI_QUOTES'

     Treat ``"'' as an identifier quote character (like the ```'' quote
     character) and not as a string quote character. You can still use
     ```'' to quote identifiers with this mode enabled. With
     `ANSI_QUOTES' enabled, you cannot use double quotes to quote
     literal strings, because it is interpreted as an identifier.

   * `ERROR_FOR_DIVISION_BY_ZERO'

     Produce an error in strict mode (otherwise a warning) when a
     division by zero (or `MOD(X,0)') occurs during an `INSERT' or
     `UPDATE'. If this mode is not enabled, MySQL instead returns
     `NULL' for divisions by zero. For `INSERT IGNORE' or `UPDATE
     IGNORE', MySQL generates a warning for divisions by zero, but the
     result of the operation is `NULL'.

   * `HIGH_NOT_PRECEDENCE'

     The precedence of the `NOT' operator is such that expressions such
     as `NOT a BETWEEN b AND c' are parsed as `NOT (a BETWEEN b AND
     c)'. In some older versions of MySQL, the expression was parsed as
     `(NOT a) BETWEEN b AND c'. The old higher-precedence behavior can
     be obtained by enabling the `HIGH_NOT_PRECEDENCE' SQL mode.

          mysql> SET sql_mode = '';
          mysql> SELECT NOT 1 BETWEEN -5 AND 5;
                  -> 0
          mysql> SET sql_mode = 'HIGH_NOT_PRECEDENCE';
          mysql> SELECT NOT 1 BETWEEN -5 AND 5;
                  -> 1

   * `IGNORE_SPACE'

     Allow spaces between a function name and the ``('' character. This
     causes built-in function names to be treated as reserved words. As
     a result, identifiers that are the same as function names must be
     quoted as described in *Note identifiers::. For example, because
     there is a `COUNT()' function, the use of `count' as a table name
     in the following statement causes an error:

          mysql> CREATE TABLE count (i INT);
          ERROR 1064 (42000): You have an error in your SQL syntax

     The table name should be quoted:

          mysql> CREATE TABLE `count` (i INT);
          Query OK, 0 rows affected (0.00 sec)

     The `IGNORE_SPACE' SQL mode applies to built-in functions, not to
     user-defined functions or stored functions. It is always allowable
     to have spaces after a UDF or stored function name, regardless of
     whether `IGNORE_SPACE' is enabled.

     For further discussion of `IGNORE_SPACE', see *Note
     function-resolution::.

   * `NO_AUTO_CREATE_USER'

     Prevent the `GRANT' statement from automatically creating new
     users if it would otherwise do so, unless a non-empty password
     also is specified.

   * `NO_AUTO_VALUE_ON_ZERO'

     `NO_AUTO_VALUE_ON_ZERO' affects handling of `AUTO_INCREMENT'
     columns. Normally, you generate the next sequence number for the
     column by inserting either `NULL' or `0' into it.
     `NO_AUTO_VALUE_ON_ZERO' suppresses this behavior for `0' so that
     only `NULL' generates the next sequence number.

     This mode can be useful if `0' has been stored in a table's
     `AUTO_INCREMENT' column. (Storing `0' is not a recommended
     practice, by the way.) For example, if you dump the table with
     `mysqldump' and then reload it, MySQL normally generates new
     sequence numbers when it encounters the `0' values, resulting in a
     table with contents different from the one that was dumped.
     Enabling `NO_AUTO_VALUE_ON_ZERO' before reloading the dump file
     solves this problem.  `mysqldump' now automatically includes in
     its output a statement that enables `NO_AUTO_VALUE_ON_ZERO', to
     avoid this problem.

   * `NO_BACKSLASH_ESCAPES'

     Disable the use of the backslash character (``\'') as an escape
     character within strings. With this mode enabled, backslash
     becomes an ordinary character like any other.

   * `NO_DIR_IN_CREATE'

     When creating a table, ignore all `INDEX DIRECTORY' and `DATA
     DIRECTORY' directives. This option is useful on slave replication
     servers.

   * `NO_ENGINE_SUBSTITUTION'

     Control automatic substitution of the default storage engine when
     a statement such as `CREATE TABLE' or `ALTER TABLE' specifies a
     storage engine that is disabled or not compiled in.

     Up through MySQL 5.1.11, with `NO_ENGINE_SUBSTITUTION' disabled,
     the default engine is used and a warning occurs if the desired
     engine is known but disabled or not compiled in. If the desired
     engine is invalid (not a known engine name), an error occurs and
     the table is not created or altered.

     With `NO_ENGINE_SUBSTITUTION' enabled, an error occurs and the
     table is not created or altered if the desired engine is
     unavailable for any reason (whether disabled or invalid).

     As of MySQL 5.1.12, storage engines can be pluggable at runtime,
     so the distinction between disabled and invalid no longer applies.
     All unavailable engines are treated the same way:

     With `NO_ENGINE_SUBSTITUTION' disabled, for `CREATE TABLE' the
     default engine is used and a warning occurs if the desired engine
     is unavailable.  For `ALTER TABLE', a warning occurs and the table
     is not altered.

     With `NO_ENGINE_SUBSTITUTION' enabled, an error occurs and the
     table is not created or altered if the desired engine is
     unavailable.

   * `NO_FIELD_OPTIONS'

     Do not print MySQL-specific column options in the output of `SHOW
     CREATE TABLE'. This mode is used by `mysqldump' in portability
     mode.

   * `NO_KEY_OPTIONS'

     Do not print MySQL-specific index options in the output of `SHOW
     CREATE TABLE'. This mode is used by `mysqldump' in portability
     mode.

   * `NO_TABLE_OPTIONS'

     Do not print MySQL-specific table options (such as `ENGINE') in
     the output of `SHOW CREATE TABLE'. This mode is used by
     `mysqldump' in portability mode.

   * `NO_UNSIGNED_SUBTRACTION'

     In integer subtraction operations, do not mark the result as
     `UNSIGNED' if one of the operands is unsigned. In other words,
     _the result of a subtraction is always signed whenever this mode
     is in effect, even if one of the operands is unsigned_.  For
     example, compare the type of column `c2' in table `t1' with that
     of column `c2' in table `t2':

          mysql> SET SQL_MODE='';
          mysql> CREATE TABLE test (c1 BIGINT UNSIGNED NOT NULL);
          mysql> CREATE TABLE t1 SELECT c1 - 1 AS c2 FROM test;
          mysql> DESCRIBE t1;
          +-------+---------------------+------+-----+---------+-------+
          | Field | Type                | Null | Key | Default | Extra |
          +-------+---------------------+------+-----+---------+-------+
          | c2    | bigint(21) unsigned |      |     | 0       |       |
          +-------+---------------------+------+-----+---------+-------+

          mysql> SET SQL_MODE='NO_UNSIGNED_SUBTRACTION';
          mysql> CREATE TABLE t2 SELECT c1 - 1 AS c2 FROM test;
          mysql> DESCRIBE t2;
          +-------+------------+------+-----+---------+-------+
          | Field | Type       | Null | Key | Default | Extra |
          +-------+------------+------+-----+---------+-------+
          | c2    | bigint(21) |      |     | 0       |       |
          +-------+------------+------+-----+---------+-------+

     Note that this means that `BIGINT UNSIGNED' is not 100% usable in
     all contexts. See *Note cast-functions::.

          mysql> SET SQL_MODE = '';
          mysql> SELECT CAST(0 AS UNSIGNED) - 1;
          +-------------------------+
          | CAST(0 AS UNSIGNED) - 1 |
          +-------------------------+
          |    18446744073709551615 |
          +-------------------------+

          mysql> SET SQL_MODE = 'NO_UNSIGNED_SUBTRACTION';
          mysql> SELECT CAST(0 AS UNSIGNED) - 1;
          +-------------------------+
          | CAST(0 AS UNSIGNED) - 1 |
          +-------------------------+
          |                      -1 |
          +-------------------------+

   * `NO_ZERO_DATE'

     In strict mode, don't allow `'0000-00-00'' as a valid date. You
     can still insert zero dates with the `IGNORE' option. When not in
     strict mode, the date is accepted but a warning is generated.

   * `NO_ZERO_IN_DATE'

     In strict mode, do not accept dates where the year part is
     non-zero but the month or day part is 0 (for example,
     `'0000-00-00'' is legal but `'2010-00-01'' and `'2010-01-00'' are
     not). If used with the `IGNORE' option, MySQL inserts a
     `'0000-00-00'' date for any such date. When not in strict mode,
     the date is accepted but a warning is generated.

   * `ONLY_FULL_GROUP_BY'

     Do not allow queries for which the `SELECT' list refers to
     non-aggregated columns that are not named in the `GROUP BY'
     clause. The following query is invalid with this mode enabled
     because `address' is not named in the `GROUP BY' clause:

          SELECT name, address, MAX(age) FROM t GROUP BY name;

     As of MySQL 5.1.11, this mode also restricts references to
     non-aggregated columns in the `HAVING' clause that are not named
     in the `GROUP BY' clause.

   * `PAD_CHAR_TO_FULL_LENGTH'

     By default, trailing spaces are trimmed from `CHAR' column values
     on retrieval. If `PAD_CHAR_TO_FULL_LENGTH' is enabled, trimming
     does not occur and retrieved `CHAR' values are padded to their full
     length. This mode does not apply to `VARCHAR' columns, for which
     trailing spaces are retained on retrieval. This mode was added in
     MySQL 5.1.20.

          mysql> CREATE TABLE t1 (c1 CHAR(10));
          Query OK, 0 rows affected (0.37 sec)

          mysql> INSERT INTO t1 (c1) VALUES('xy');
          Query OK, 1 row affected (0.01 sec)

          mysql> SET sql_mode = '';
          Query OK, 0 rows affected (0.00 sec)

          mysql> SELECT c1, CHAR_LENGTH(c1) FROM t1;
          +------+-----------------+
          | c1   | CHAR_LENGTH(c1) |
          +------+-----------------+
          | xy   |               2 |
          +------+-----------------+
          1 row in set (0.00 sec)

          mysql> SET sql_mode = 'PAD_CHAR_TO_FULL_LENGTH';
          Query OK, 0 rows affected (0.00 sec)

          mysql> SELECT c1, CHAR_LENGTH(c1) FROM t1;
          +------------+-----------------+
          | c1         | CHAR_LENGTH(c1) |
          +------------+-----------------+
          | xy         |              10 |
          +------------+-----------------+
          1 row in set (0.00 sec)

   * `PIPES_AS_CONCAT'

     Treat `||' as a string concatenation operator (same as `CONCAT()')
     rather than as a synonym for `OR'.

   * `REAL_AS_FLOAT'

     Treat `REAL' as a synonym for `FLOAT'. By default, MySQL treats
     `REAL' as a synonym for `DOUBLE'.

   * `STRICT_ALL_TABLES'

     Enable strict mode for all storage engines. Invalid data values
     are rejected. Additional detail follows.

   * `STRICT_TRANS_TABLES'

     Enable strict mode for transactional storage engines, and when
     possible for non-transactional storage engines.  Additional
     details follow.

Strict mode controls how MySQL handles input values that are invalid or
missing. A value can be invalid for several reasons.  For example, it
might have the wrong data type for the column, or it might be out of
range. A value is missing when a new row to be inserted does not
contain a value for a non-`NULL' column that has no explicit `DEFAULT'
clause in its definition. (For a `NULL' column, `NULL' is inserted if
the value is missing.)

For transactional tables, an error occurs for invalid or missing values
in a statement when either of the `STRICT_ALL_TABLES' or
`STRICT_TRANS_TABLES' modes are enabled. The statement is aborted and
rolled back.

For non-transactional tables, the behavior is the same for either mode,
if the bad value occurs in the first row to be inserted or updated. The
statement is aborted and the table remains unchanged. If the statement
inserts or modifies multiple rows and the bad value occurs in the
second or later row, the result depends on which strict option is
enabled:

   * For `STRICT_ALL_TABLES', MySQL returns an error and ignores the
     rest of the rows. However, in this case, the earlier rows still
     have been inserted or updated.  This means that you might get a
     partial update, which might not be what you want. To avoid this,
     it's best to use single-row statements because these can be
     aborted without changing the table.

   * For `STRICT_TRANS_TABLES', MySQL converts an invalid value to the
     closest valid value for the column and insert the adjusted value.
     If a value is missing, MySQL inserts the implicit default value
     for the column data type.  In either case, MySQL generates a
     warning rather than an error and continues processing the
     statement. Implicit defaults are described in *Note
     data-type-defaults::.

Strict mode disallows invalid date values such as `'2004-04-31''. It
does not disallow dates with zero month or day parts such as
`'2004-04-00'' or `zero' dates. To disallow these as well, enable the
`NO_ZERO_IN_DATE' and `NO_ZERO_DATE' SQL modes in addition to strict
mode.

If you are not using strict mode (that is, neither
`STRICT_TRANS_TABLES' nor `STRICT_ALL_TABLES' is enabled), MySQL inserts
adjusted values for invalid or missing values and produces warnings. In
strict mode, you can produce this behavior by using `INSERT IGNORE' or
`UPDATE IGNORE'. See *Note show-warnings::.

Strict mode does not affect whether foreign key constraints are
checked. `FOREIGN_KEY_CHECKS' can be used for that. (See *Note
server-session-variables::.)

The following special modes are provided as shorthand for combinations
of mode values from the preceding list.

The descriptions include all mode values that are available in the most
recent version of MySQL. For older versions, a combination mode does
not include individual mode values that are not available except in
newer versions.

   * `ANSI'

     Equivalent to `REAL_AS_FLOAT', `PIPES_AS_CONCAT', `ANSI_QUOTES',
     `IGNORE_SPACE'.

     As of MySQL 5.1.18, `ANSI' mode also causes the server to return
     an error for queries where a set function S with an outer reference
     `S(OUTER_REF)' cannot be aggregated in the outer query against
     which the outer reference has been resolved. This is such a query:

          SELECT * FROM t1 WHERE t1.a IN (SELECT MAX(t1.b) FROM t2 WHERE ...);

     Here, `MAX(t1.b)' cannot aggregated in the outer query because it
     appears in the `WHERE' clause of that query. Standard SQL requires
     an error in this situation. If `ANSI' mode is not enabled, the
     server treats `S(OUTER_REF)' in such queries the same way that it
     would interpret `S(CONST)', as was always done prior to 5.1.18.

     See *Note ansi-mode::.

   * `DB2'

     Equivalent to `PIPES_AS_CONCAT', `ANSI_QUOTES', `IGNORE_SPACE',
     `NO_KEY_OPTIONS', `NO_TABLE_OPTIONS', `NO_FIELD_OPTIONS'.

   * `MAXDB'

     Equivalent to `PIPES_AS_CONCAT', `ANSI_QUOTES', `IGNORE_SPACE',
     `NO_KEY_OPTIONS', `NO_TABLE_OPTIONS', `NO_FIELD_OPTIONS',
     `NO_AUTO_CREATE_USER'.

   * `MSSQL'

     Equivalent to `PIPES_AS_CONCAT', `ANSI_QUOTES', `IGNORE_SPACE',
     `NO_KEY_OPTIONS', `NO_TABLE_OPTIONS', `NO_FIELD_OPTIONS'.

   * `MYSQL323'

     Equivalent to `NO_FIELD_OPTIONS', `HIGH_NOT_PRECEDENCE'.

   * `MYSQL40'

     Equivalent to `NO_FIELD_OPTIONS', `HIGH_NOT_PRECEDENCE'.

   * `ORACLE'

     Equivalent to `PIPES_AS_CONCAT', `ANSI_QUOTES', `IGNORE_SPACE',
     `NO_KEY_OPTIONS', `NO_TABLE_OPTIONS', `NO_FIELD_OPTIONS',
     `NO_AUTO_CREATE_USER'.

   * `POSTGRESQL'

     Equivalent to `PIPES_AS_CONCAT', `ANSI_QUOTES', `IGNORE_SPACE',
     `NO_KEY_OPTIONS', `NO_TABLE_OPTIONS', `NO_FIELD_OPTIONS'.

   * `TRADITIONAL'

     Equivalent to `STRICT_TRANS_TABLES', `STRICT_ALL_TABLES',
     `NO_ZERO_IN_DATE', `NO_ZERO_DATE', `ERROR_FOR_DIVISION_BY_ZERO',
     `NO_AUTO_CREATE_USER'.


File: manual.info,  Node: server-side-help-support,  Next: server-signal-response,  Prev: server-sql-mode,  Up: mysqld-server

5.1.8 Server-Side Help
----------------------

MySQL Server supports a `HELP' statement that returns online
information from the MySQL Reference manual (see *Note help::). The
proper operation of this statement requires that the help tables in the
`mysql' database be initialized with help topic information, which is
done by processing the contents of the `fill_help_tables.sql' script.

For a MySQL binary distribution on Unix, help table setup occurs when
you run `mysql_install_db'. For an RPM distribution on Linux or binary
distribution on Windows, help table setup occurs as part of the MySQL
installation process.

For a MySQL source distribution, you can find the
`fill_help_tables.sql' file in the `scripts' directory. To load the file
manually, make sure that you have initialized the `mysql' database by
running `mysql_install_db', and then process the file with the `mysql'
client as follows:

     shell> mysql -u root mysql < fill_help_tables.sql

If you are working with Bazaar and a MySQL development source tree, the
tree doesn't contain `fill_help_tables.sql'. You can download the
proper file for your version of MySQL from `http://dev.mysql.com/doc/'.
After downloading and uncompressing the file, process it with `mysql'
as just described.


File: manual.info,  Node: server-signal-response,  Next: server-shutdown,  Prev: server-side-help-support,  Up: mysqld-server

5.1.9 Server Response to Signals
--------------------------------

On Unix, signals can be sent to processes.  `mysqld' responds to
signals sent to it as follows:

   * `SIGTERM' causes the server to shut down.

   * `SIGHUP' causes the server to reload the grant tables and flush
     the logs (like `FLUSH PRIVILEGES' and `FLUSH LOGS'). It also
     writes a status report to the error log that has this format:

          Status information:

          Current dir: /var/mysql/data/
          Running threads: 0  Stack size: 196608
          Current locks:

          Key caches:
          default
          Buffer_size:       8388600
          Block_size:           1024
          Division_limit:        100
          Age_limit:             300
          blocks used:             0
          not flushed:             0
          w_requests:              0
          writes:                  0
          r_requests:              0
          reads:                   0

          handler status:
          read_key:            0
          read_next:           0
          read_rnd             0
          read_first:          1
          write:               0
          delete               0
          update:              0

          Table status:
          Opened tables:          5
          Open tables:            0
          Open files:             7
          Open streams:           0

          Alarm status:
          Active alarms:   1
          Max used alarms: 2
          Next alarm time: 67

On some Mac OS X 10.3 versions, `mysqld' ignores `SIGHUP' and `SIGQUIT'.


File: manual.info,  Node: server-shutdown,  Prev: server-signal-response,  Up: mysqld-server

5.1.10 The Shutdown Process
---------------------------

The server shutdown process takes place as follows:

  1. The shutdown process is initiated.

     Server shutdown can be initiated several ways. For example, a user
     with the `SHUTDOWN' privilege can execute a `mysqladmin shutdown'
     command.  `mysqladmin' can be used on any platform supported by
     MySQL. Other operating system-specific shutdown initiation methods
     are possible as well: The server shuts down on Unix when it
     receives a `SIGTERM' signal. A server running as a service on
     Windows shuts down when the services manager tells it to.

  2. The server creates a shutdown thread if necessary.

     Depending on how shutdown was initiated, the server might create a
     thread to handle the shutdown process. If shutdown was requested
     by a client, a shutdown thread is created. If shutdown is the
     result of receiving a `SIGTERM' signal, the signal thread might
     handle shutdown itself, or it might create a separate thread to do
     so. If the server tries to create a shutdown thread and cannot
     (for example, if memory is exhausted), it issues a diagnostic
     message that appears in the error log:

          Error: Can't create thread to kill server

  3. The server stops accepting new connections.

     To prevent new activity from being initiated during shutdown, the
     server stops accepting new client connections.  It does this by
     closing the network connections to which it normally listens for
     connections: the TCP/IP port, the Unix socket file, the Windows
     named pipe, and shared memory on Windows.

  4. The server terminates current activity.

     For each thread that is associated with a client connection, the
     connection to the client is broken and the thread is marked as
     killed. Threads die when they notice that they are so marked.
     Threads for idle connections die quickly. Threads that currently
     are processing statements check their state periodically and take
     longer to die. For additional information about thread
     termination, see *Note kill::, in particular for the instructions
     about killed `REPAIR TABLE' or `OPTIMIZE TABLE' operations on
     `MyISAM' tables.

     For threads that have an open transaction, the transaction is
     rolled back. Note that if a thread is updating a non-transactional
     table, an operation such as a multiple-row `UPDATE' or `INSERT' may
     leave the table partially updated, because the operation can
     terminate before completion.

     If the server is a master replication server, threads associated
     with currently connected slaves are treated like other client
     threads. That is, each one is marked as killed and exits when it
     next checks its state.

     If the server is a slave replication server, the I/O and SQL
     threads, if active, are stopped before client threads are marked
     as killed. The SQL thread is allowed to finish its current
     statement (to avoid causing replication problems), and then stops.
     If the SQL thread was in the middle of a transaction at this
     point, the transaction is rolled back.

  5. Storage engines are shut down or closed.

     At this stage, the table cache is flushed and all open tables are
     closed.

     Each storage engine performs any actions necessary for tables that
     it manages. For example, `MyISAM' flushes any pending index writes
     for a table. `InnoDB' flushes its buffer pool to disk, unless
     `innodb_fast_shutdown' is 2, writes the current LSN to the
     tablespace, and terminates its own internal threads.

  6. The server exits.


File: manual.info,  Node: log-files,  Next: security,  Prev: mysqld-server,  Up: server-administration

5.2 MySQL Server Logs
=====================

* Menu:

* log-tables::                   Selecting General Query and Slow Query Log Output Destinations
* error-log::                    The Error Log
* query-log::                    The General Query Log
* binary-log::                   The Binary Log
* slow-query-log::               The Slow Query Log
* log-file-maintenance::         Server Log Maintenance

MySQL has several different logs that can help you find out what is
going on inside `mysqld':

*Log Type*             *Information Written to Log*
The error log          Problems encountered starting, running, or
                       stopping `mysqld'
The general query log  Established client connections and statements
                       received from clients
The binary log         All statements that change data (also used for
                       replication)
The slow query log     All queries that took more than `long_query_time'
                       seconds to execute or didn't use indexes

By default, all log files are created in the `mysqld' data directory.
You can force `mysqld' to close and reopen the log files (or in some
cases switch to a new log) by flushing the logs. Log flushing occurs
when you issue a `FLUSH LOGS' statement or execute `mysqladmin
flush-logs' or `mysqladmin refresh'. See *Note flush::, and *Note
mysqladmin::.

If you are using MySQL replication capabilities, slave replication
servers maintain additional log files called relay logs.  *Note
replication::, discusses relay log contents and configuration.

MySQL Enterprise

The MySQL Enterprise Monitor provides a number of advisors specifically
related to the various log files. For more information see
`http://www.mysql.com/products/enterprise/advisors.html'.

As of MySQL 5.1.6, the server can write general query and slow query
entries to log tables, log files, or both. For details, see *Note
log-tables::.

As of MySQL 5.1.12, additional runtime control of the general query and
slow query logs is available: You can enable or disable logging, or
change the name of the log file. See *Note query-log::, and *Note
slow-query-log::.


File: manual.info,  Node: log-tables,  Next: error-log,  Prev: log-files,  Up: log-files

5.2.1 Selecting General Query and Slow Query Log Output Destinations
--------------------------------------------------------------------

As of MySQL 5.1.6, the server provides flexible control over the
destination for log output. Log entries can be written to log files to
the `general_log' and `slow_log' tables in the `mysql' database. If
logging is enabled, either or both destinations can be selected.
(Before MySQL 5.1.6, the server uses only log files as the destination
for general query log and slow query log entries, if those logs are
enabled.)

*Note*:

For new installations of MySQL 5.1.6 or higher, the log tables are
created during the installation procedure along with the other system
tables. If you upgrade MySQL from a release older than 5.1.6 to MySQL
5.1.6 or higher, you must upgrade the system tables after upgrading to
make sure that the log tables exist. See *Note mysql-upgrade::.

Currently, logging to tables incurs significantly more server overhead
than logging to files. If you enable the general log or slow query log
and require highest performance, you should log to files and not to
tables.

The `--log-output' option specifies the destination for log output, if
logging is enabled, but the option does not in itself enable the logs.
The syntax for this option is `--log-output[=VALUE,...]':

   * If `--log-output' is given with a value, the value can be a
     comma-separated list of one or more of the words `TABLE' (log to
     tables), `FILE' (log to files), or `NONE' (do not log to tables or
     files).  `NONE', if present, takes precedence over any other
     specifiers.

   * If `--log-output' is omitted or given without a value, the effect
     is the same as `--log-output=FILE'. That is, the file destination
     is selected. (For MySQL 5.1.6 through 5.1.20, the default is the
     table destination.)

   * If `--log-output' option also sets the value of the global
     `log_output' system variable, which can be modified at runtime to
     change the logging destination for the server while it executes.

The `--log[=FILE_NAME]' option, if given, enables logging to the
general query log for the selected log destinations. Similarly, the
`--log-slow-queries[=FILE_NAME]' option, if given, enables logging to
the slow query log for the selected destinations. If you specify either
option, the server opens the corresponding log file and writes startup
messages to it. However, logging of queries to the file does not occur
unless the `FILE' log destination is selected.

Examples:

   * To write general query log entries to the log table and the log
     file, use `--log-output=TABLE,FILE' to select both log
     destinations and the `--log' option to enable the general query
     log.

   * To write general and slow query log entries only to the log
     tables, use `--log-output=TABLE' to select tables as the log
     destination and the `--log' and `--log-slow-queries' options to
     enable both logs.

   * To write slow query log entries only to the log file, use
     `--log-output=FILE' to select files as the log destination and the
     `--log-slow-queries' option to enable the slow query log. (In this
     case, because the default log destination is `FILE', you could
     omit the `--log-output' option.)

Several system variables are associated with log tables and files:

   * The global `general_log' and `slow_query_log' variables indicate
     whether the general query log and slow query log are enabled
     (`ON') or disabled (`OFF'). You can set these variables at runtime
     to control whether the logs are enabled.

   * The global `general_log_file' and `slow_query_log_file' variables
     indicate the names of the general query log and slow query log
     files.  You can set these variables at runtime to change the names
     of the log files. (If the `--log' and `--log-slow-queries' options
     were not given, the initial variable values are the default log
     filenames.)

   * The session `sql_log_off' variable can be set to `ON' or `OFF' to
     disable or enable general query logging for the current connection.

The use of tables for log output offers the following benefits:

   * Log entries have a standard format. To display the current
     structure of the log tables, use these statements:

          SHOW CREATE TABLE mysql.general_log;
          SHOW CREATE TABLE mysql.slow_log;

   * Log contents are accessible via SQL statements. This enables the
     use of queries that select only those log entries that satisfy
     specific criteria. For example, to select log contents associated
     with a particular client (which can be useful for identifying
     problematic queries from that client), it is easier to do this
     using a log table than a log file.

   * Logs are accessible remotely through any client that can connect
     to the server and issue queries (if the client has the appropriate
     log table privileges). It's not necessary to log in to the server
     host and directly access the filesystem.

The log table implementation has the following characteristics:

   * In general, the primary purpose of log tables is to provide an
     interface for users to observe the runtime execution of the
     server, not to interfere with its runtime execution.

   * `CREATE TABLE', `ALTER TABLE', and `DROP TABLE' are valid
     operations on a log table. For `ALTER TABLE' and `DROP TABLE', the
     log table cannot be in use and must be disabled, as described
     later.

   * By default, the log tables use the `CSV' storage engine that
     writes data in comma-separated values format. For users who have
     access to the `.CSV' files that contain log table data, the files
     are easy to import into other programs such as spreadsheets that
     can process CSV input.

     Beginning with MySQL 5.1.12, the log tables can be altered to use
     the `MyISAM' storage engine. You cannot use `ALTER TABLE' to alter
     a log table that is in use. The log must be disabled first. No
     engines other than `CSV' or `MyISAM' are legal for the log tables.

   * To disable logging so that you can alter (or drop) a log table,
     you can use the following strategy. The example uses the general
     query log; the procedure for the slow query log is similar but
     uses the `slow_log' table and `slow_query_log' system variable.

          SET @old_log_state = @@global.general_log;
          SET GLOBAL general_log = 'OFF';
          ALTER TABLE mysql.general_log ENGINE = MyISAM;
          SET GLOBAL general_log = @old_log_state;

   * `TRUNCATE TABLE' is a valid operation on a log table. It can be
     used to expire log entries.

   * As of MySQL 5.1.13, `RENAME TABLE' is a valid operation on a log
     table. You can atomically rename a log table (to perform log
     rotation, for example) using the following strategy:

          USE mysql;
          CREATE TABLE IF NOT EXISTS general_log2 LIKE general_log;
          RENAME TABLE general_log TO general_log_backup, general_log2 TO general_log;

   * `LOCK TABLES' cannot be used on a log table.

   * `INSERT', `DELETE', and `UPDATE' cannot be used on a log table.
     These operations are allowed only internally to the server itself.

   * The global read lock and the state of the global `read_only'
     system variable have no effect on log tables. The server can
     always write to the log tables.

   * Entries written to the log tables are not written to the binary
     log and thus are not replicated to slave servers.

   * To flush the log tables or log files, use `FLUSH TABLES' or `FLUSH
     LOGS', respectively. (From MySQL 5.1.12 to 5.1.20, `FLUSH TABLES'
     ignores log tables and `FLUSH LOGS' flushes both the log tables
     and files.)

   * It is not recommended to partition log tables, and doing so is not
     allowed beginning with MySQL 5.1.20.


File: manual.info,  Node: error-log,  Next: query-log,  Prev: log-tables,  Up: log-files

5.2.2 The Error Log
-------------------

The error log contains information indicating when `mysqld' was started
and stopped and also any critical errors that occur while the server is
running. If `mysqld' notices a table that needs to be automatically
checked or repaired, it writes a message to the error log.

On some operating systems, the error log contains a stack trace if
`mysqld' dies. The trace can be used to determine where `mysqld' died.
See MySQL Internals: Porting
(http://forge.mysql.com/wiki/MySQL_Internals_Porting).

You can specify where `mysqld' writes the error log with the
`--log-error[=FILE_NAME]' option. If no FILE_NAME value is given,
`mysqld' uses the name `HOST_NAME.err' by default and writes the file
in the data directory. If you execute `FLUSH LOGS', the error log is
renamed with the suffix `-old' and `mysqld' creates a new empty log
file. (No renaming occurs if the `--log-error' option was not given to
`mysqld'.)

If you do not specify `--log-error', or (on Windows) if you use the
`--console' option, errors are written to `stderr', the standard error
output. Usually this is your terminal.

On Windows, error output is always written to the `.err' file if
`--console' is not given.

The `--log-warnings' option or `log_warnings' system variable can be
used to control warning logging to the error log. The default value is
enabled (1). Warning logging can be disabled using a value of 0.  If
the value is greater than 1, aborted connections are written to the
error log. See *Note communication-errors::.

If you use `mysqld_safe' to start `mysqld', `mysqld_safe' arranges for
`mysqld' to write error messages to a log file or (as of MySQL 5.1.20)
to `syslog':

   * Before 5.1.20, `mysqld_safe' behavior is to log to a file, using
     the default error log file if the `--log-error' option is not
     given to `mysqld_safe'. Otherwise, `mysqld_safe' uses the filename
     specified via `--log-error=FILE_NAME'.

   * From 5.1.20 on, `mysqld_safe' has two additional error-logging
     options, `--syslog' and `--skip-syslog'.

     In 5.1.21 and up, the default with no logging options is
     `--skip-syslog', which is compatible with the default behavior of
     writing an error log file for releases prior to 5.1.20. To
     explicitly specify use of an error log file, specify
     `--log-error=FILE_NAME' to `mysqld_safe', and `mysqld_safe' will
     arrange for `mysqld' to write messages to a log file.  To use
     `syslog' instead, specify the `--syslog' option.

     *In 5.1.20 _only_, the following conditions apply*: 1) The default
     is to use `syslog', which is not compatible with releases prior to
     5.1.20. 2) Logging to `syslog' may fail to operate correctly in
     some cases, so we recommend that you use `--skip-syslog' or
     `--log-error'.

     For logging to `syslog', messages from `mysqld_safe' and `mysqld'
     are written with a tag of `mysqld_safe' and `mysqld',
     respectively. As of MySQL 5.1.21, to specify a suffix for the tag,
     use `--syslog-tag=TAG', which modifies the tags to be
     `mysqld_safe-TAG' and `mysqld-TAG'.

If you specify `--log-error' in an option file in a section that
`mysqld' reads, `mysqld_safe' also will find and use the option.

If `mysqld_safe' is used to start `mysqld' and `mysqld' dies
unexpectedly, `mysqld_safe' notices that it needs to restart `mysqld'
and writes a `restarted mysqld' message to the error log.


File: manual.info,  Node: query-log,  Next: binary-log,  Prev: error-log,  Up: log-files

5.2.3 The General Query Log
---------------------------

The general query log is a general record of what `mysqld' is doing.
The server writes information to this log when clients connect or
disconnect, and it logs each SQL statement received from clients. The
general query log can be very useful when you suspect an error in a
client and want to know exactly what the client sent to `mysqld'.

`mysqld' writes statements to the query log in the order that it
receives them, which might differ from the order in which they are
executed. This logging order contrasts to the binary log, for which
statements are written after they are executed but before any locks are
released. (Also, the query log contains all statements, whereas the
binary log does not contain statements that only select data.)

To enable the general query log as of MySQL 5.1.6, start `mysqld' with
the `--log[=FILE_NAME]' or `-l [FILE_NAME]' option, and optionally use
`--log-output' to specify the log destination (as described in *Note
log-tables::). Before 5.1.6, the general query log destination is
always a file. To enable the general query log file, use the
`--log[=FILE_NAME]' or `-l [FILE_NAME]' option.

If no FILE_NAME value is given for `--log' or `-l', the default name is
`HOST_NAME.log' in the data directory. If a filename is given, but not
as an absolute pathname, the server writes the file in the data
directory.

When `--log' or `-l' is specified, the `--general-log' option also may
be given as of MySQL 5.1.12 to specify the initial general query log
state.  With no argument or an argument of 0, the option disables the
log. If omitted or given with an argument of 1, the option enables the
log. If `--log' or `-l' is not specified, `--general-log' has no effect.

The global `general_log' and `general_log_file' system variables provide
runtime control over the general query log. Set `general_log' to 0 (or
`OFF') to disable the log or to 1 (or `ON') to enable it. Set
`general_log_file' to specify the name of the log file. If a log file
already is open, it is closed and the new file is opened.

When the general query log is enabled, output is written to any
destinations specified by the `--log-output' option or `log_output'
system variable. Note that if the destination is `NONE', no output is
written even if the general log is enabled. Setting the log filename
has no effect on logging if the log destination value does not contain
`FILE'.

Server restarts and log flushing do not cause a new general query log
file to be generated (although flushing closes and reopens it). On
Unix, you can rename the file and create a new one by using the
following commands:

     shell> mv HOST_NAME.log HOST_NAME-old.log
     shell> mysqladmin flush-logs
     shell> cp HOST_NAME-old.log BACKUP-DIRECTORY
     shell> rm HOST_NAME-old.log

Before 5.1.3, you cannot rename a log file on Windows while the server
has it open. You must stop the server and rename the file, and then
restart the server to create a new log file. As of 5.1.3, this applies
only to the error log. However, a stop and restart can be avoided by
using `FLUSH LOGS', which causes the server to rename the error log
with an `-old' suffix and open a new error log.

As of MySQL 5.1.12, you can disable the general query log at runtime:

     SET GLOBAL general_log = 'OFF';

With the log disabled, rename the log file externally; for example,
from the command line. Then enable the log again:

     SET GLOBAL general_log = 'ON';

This method works on any platform and does not require a server restart.

The session `sql_log_off' variable can be set to `ON' or `OFF' to
disable or enable general query logging for the current connection.


File: manual.info,  Node: binary-log,  Next: slow-query-log,  Prev: query-log,  Up: log-files

5.2.4 The Binary Log
--------------------

* Menu:

* binary-log-formats::           Binary Logging Formats
* binary-log-setting::           Setting The Binary Log Format
* binary-log-mixed::             Mixed Binary Logging Format
* binary-log-mysql-database::    Logging Format for Changes to `mysql' Database Tables

The binary log contains all statements that update data or potentially
could have updated it (for example, a `DELETE' which matched no rows).
Statements are stored in the form of `events' that describe the
modifications. The binary log also contains information about how long
each statement took that updated data. The binary log has two important
purposes:

   * For replication, the binary log is used on master replication
     servers as a record of the statements to be sent to slave servers.
     The master server sends the events contained in its binary log to
     its slaves, which execute those events to make the same data
     changes that were made on the master. See *Note
     replication-implementation::.

   * Certain data recovery operations require use of the binary log.
     After a backup file has been restored, the events in the binary
     log that were recorded after the backup was made are re-executed.
     These events bring databases up to date from the point of the
     backup. See *Note recovery-from-backups::.

The binary log is not used for statements such as `SELECT' or `SHOW'
that do not modify data. If you want to log all statements (for
example, to identify a problem query), use the general query log. See
*Note query-log::.

The format of the events recorded in the binary log is dependent on the
binary logging format. Three format types are supported, row-based
logging, statement-based logging and mixed-base logging. The binary
logging format used depends on the MySQL version. For more information
on logging formats, see *Note binary-log-formats::.

MySQL Enterprise

The binary log can also be used to track significant DDL events.
Analyzing the binary log in this way is an integral part of the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

Running the server with the binary log enabled makes performance about
1% slower. However, the benefits of the binary log for restore
operations and in allowing you to set up replication generally outweigh
this minor performance decrement.

When started with the `--log-bin[=BASE_NAME]' option, `mysqld' writes a
log file containing all SQL statements that update data (both DDL and
DML statements). If no BASE_NAME value is given, the default name is
the value of the `pid-file' option (which by default is the name of
host machine) followed by `-bin'. If the basename is given, but not as
an absolute pathname, the server writes the file in the data directory.
It is recommended that you specify a basename; see *Note open-bugs::,
for the reason.

*Note*:

From MySQL 5.1.18 through 5.1.22, `mysql' was used when no BASE_NAME was
specified. Also in these versions, a path given as part of the
`--log-bin' options was treated as absolute rather than relative. The
previous behaviors were restored in MySQL 5.1.23. (See Bug#28603
(http://bugs.mysql.com/28603) and Bug#28597
(http://bugs.mysql.com/28597).)

If you supply an extension in the log name (for example,
`--log-bin=BASE_NAME.EXTENSION'), the extension is silently removed and
ignored.

`mysqld' appends a numeric extension to the binary log basename to
generate binary log filenames. The number increases each time the
server creates a new log file, thus creating an ordered series of
files. The server creates a new file in the series each time it starts
or flushes the logs. The server also creates a new binary log file
automatically when the current log's size reaches `max_binlog_size'. A
binary log file may become larger than `max_binlog_size' if you are
using large transactions because a transaction is written to the file
in one piece, never split between files.

To keep track of which binary log files have been used, `mysqld' also
creates a binary log index file that contains the names of all used
binary log files. By default, this has the same basename as the binary
log file, with the extension `'.index''. You can change the name of the
binary log index file with the `--log-bin-index[=FILE_NAME]' option.
You should not manually edit this file while `mysqld' is running; doing
so would confuse `mysqld'.

You can delete all binary log files with the `RESET MASTER' statement,
or a subset of them with `PURGE MASTER LOGS'. See *Note reset::, and
*Note purge-master-logs::.

Writes to the binary log file and binary log index file are handled in
the same way as writes to `MyISAM' tables. See *Note full-disk::.

The binary log format has some known limitations that can affect
recovery from backups. See *Note replication-features::.

Binary logging for stored routines and triggers is done as described in
*Note stored-procedure-logging::.

A replication slave server by default does not write to its own binary
log any data modifications that are received from the replication
master. To log these modifications, start the slave with the
`--log-slave-updates' option.

You can use the following options to `mysqld' to affect what is logged
to the binary log. See also the discussion that follows this option
list.

If you are using replication, the options described here affect which
statements are sent by a master server to its slaves.  There are also
options for slave servers that control which statements received from
the master to execute or ignore. For details, see *Note
replication-options::.

   *  `--binlog-do-db=DB_NAME'

     Tell the server to restrict binary logging to updates for which
     the default database is DB_NAME (that is, the database selected by
     `USE'). All other databases that are not explicitly mentioned are
     ignored. If you use this option, you should ensure that you do
     updates only in the default database.

     There is an exception to this for `CREATE DATABASE', `ALTER
     DATABASE', and `DROP DATABASE' statements. The server uses the
     database named in the statement (not the default database) to
     decide whether it should log the statement.

     An example of what does not work as you might expect: If the
     server is started with `binlog-do-db=sales', and you run `USE
     prices; UPDATE sales.january SET amount=amount+1000;', this
     statement is _not_ written into the binary log.

     To log multiple databases, use multiple options, specifying the
     option once for each database.

   *  `--binlog-ignore-db=DB_NAME'

     Tell the server to suppress binary logging of updates for which
     the default database is DB_NAME (that is, the database selected by
     `USE'). If you use this option, you should ensure that you do
     updates only in the default database.

     As with the `--binlog-do-db' option, there is an exception for the
     `CREATE DATABASE', `ALTER DATABASE', and `DROP DATABASE'
     statements. The server uses the database named in the statement
     (not the default database) to decide whether it should log the
     statement.

     An example of what does not work as you might expect: If the
     server is started with `binlog-ignore-db=sales', and you run `USE
     prices; UPDATE sales.january SET amount=amount+1000;', this
     statement _is_ written into the binary log.

     To ignore multiple databases, use multiple options, specifying the
     option once for each database.

The server evaluates the options for logging or ignoring updates to the
binary log according to the following rules. As described previously,
there is an exception for the `CREATE DATABASE', `ALTER DATABASE', and
`DROP DATABASE' statements. In those cases, the database being
_created, altered, or dropped_ replaces the default database in the
following rules:

  1. Are there `--binlog-do-db' or `--binlog-ignore-db' rules?

        * No: Write the statement to the binary log and exit.

        * Yes: Go to the next step.

  2. There are some rules (`--binlog-do-db', `--binlog-ignore-db', or
     both). Is there a default database (has any database been selected
     by `USE'?)?

        * No: Do _not_ write the statement, and exit.

        * Yes: Go to the next step.

  3. There is a default database. Are there some `--binlog-do-db' rules?

        * Yes: Does the default database match any of the
          `--binlog-do-db' rules?

             * Yes: Write the statement and exit.

             * No: Do _not_ write the statement, and exit.

        * No: Go to the next step.

  4. There are some `--binlog-ignore-db' rules.  Does the default
     database match any of the `--binlog-ignore-db' rules?

        * Yes: Do not write the statement, and exit.

        * No: Write the query and exit.

For example, a slave running with only `--binlog-do-db=sales' does not
write to the binary log any statement for which the default database is
different from `sales' (in other words, `--binlog-do-db' can sometimes
mean `ignore other databases').

If you are using replication, you should not delete old binary log
files until you are sure that no slave still needs to use them. For
example, if your slaves never run more than three days behind, once a
day you can execute `mysqladmin flush-logs' on the master and then
remove any logs that are more than three days old. You can remove the
files manually, but it is preferable to use `PURGE MASTER LOGS', which
also safely updates the binary log index file for you (and which can
take a date argument). See *Note purge-master-logs::.

A client that has the `SUPER' privilege can disable binary logging of
its own statements by using a `SET SQL_LOG_BIN=0' statement. See *Note
server-session-variables::.

You can display the contents of binary log files with the `mysqlbinlog'
utility. This can be useful when you want to reprocess statements in
the log. For example, you can update a MySQL server from the binary log
as follows:

     shell> mysqlbinlog LOG_FILE | mysql -h SERVER_NAME

See *Note mysqlbinlog::, for more information on the `mysqlbinlog'
utility and how to use it.  `mysqlbinlog' also can be used with relay
log files because they are written using the same format as binary log
files.

Binary logging is done immediately after a statement completes but
before any locks are released or any commit is done. This ensures that
the log is logged in execution order.

Updates to non-transactional tables are stored in the binary log
immediately after execution. Within an uncommitted transaction, all
updates (`UPDATE', `DELETE', or `INSERT') that change transactional
tables such as `InnoDB' tables are cached until a `COMMIT' statement is
received by the server. At that point, `mysqld' writes the entire
transaction to the binary log before the `COMMIT' is executed. When the
thread that handles the transaction starts, it allocates a buffer of
`binlog_cache_size' to buffer statements. If a statement is bigger than
this, the thread opens a temporary file to store the transaction. The
temporary file is deleted when the thread ends.

Modifications to non-transactional tables cannot be rolled back.  If a
transaction that is rolled back includes modifications to
non-transactional tables, the entire transaction is logged with a
`ROLLBACK' statement at the end to ensure that the modifications to
those tables are replicated.

The `Binlog_cache_use' status variable shows the number of transactions
that used this buffer (and possibly a temporary file) for storing
statements. The `Binlog_cache_disk_use' status variable shows how many
of those transactions actually had to use a temporary file. These two
variables can be used for tuning `binlog_cache_size' to a large enough
value that avoids the use of temporary files.

The `max_binlog_cache_size' system variable (default 4GB, which is also
the maximum) can be used to restrict the total size used to cache a
multiple-statement transaction.  If a transaction is larger than this
many bytes, it fails and rolls back. The minimum value is 4096.

If you are using the binary log and row based logging, concurrent
inserts are converted to normal inserts for `CREATE ... SELECT' or
`INSERT ...  SELECT' statement. This is done to ensure that you can
re-create an exact copy of your tables by applying the log during a
backup operation. If you are using statement based logging then the
original statement is written to the log.

Note that the binary log format is different in MySQL 5.1 from previous
versions of MySQL, due to enhancements in replication. See *Note
replication-compatibility::.

By default, the binary log is not synchronized to disk at each write.
So if the operating system or machine (not only the MySQL server)
crashes, there is a chance that the last statements of the binary log
are lost. To prevent this, you can make the binary log be synchronized
to disk after every N writes to the binary log, with the `sync_binlog'
system variable. See *Note server-system-variables::. 1 is the safest
value for `sync_binlog', but also the slowest. Even with `sync_binlog'
set to 1, there is still the chance of an inconsistency between the
table content and binary log content in case of a crash. For example,
if you are using `InnoDB' tables and the MySQL server processes a
`COMMIT' statement, it writes the whole transaction to the binary log
and then commits this transaction into `InnoDB'. If the server crashes
between those two operations, the transaction is rolled back by
`InnoDB' at restart but still exists in the binary log. To resolve
this, you should set `--innodb_support_xa' to 1. Although this option
is related to the support of XA transactions in InnoDB, it also ensures
that the binary log and InnoDB data files are synchronized.

For this option to provide a greater degree of safety, the MySQL server
should also be configured to synchronize the binary log and the
`InnoDB' logs to disk at every transaction. The `InnoDB' logs are
synchronized by default, and `sync_binlog=1' can be used to synchronize
the binary log. The effect of this option is that at restart after a
crash, after doing a rollback of transactions, the MySQL server cuts
rolled back `InnoDB' transactions from the binary log. This ensures
that the binary log reflects the exact data of `InnoDB' tables, and so,
that the slave remains in synchrony with the master (not receiving a
statement which has been rolled back).

If the MySQL server discovers at crash recovery that the binary log is
shorter than it should have been, it lacks at least one successfully
committed `InnoDB' transaction.  This should not happen if
`sync_binlog=1' and the disk/filesystem do an actual sync when they are
requested to (some don't), so the server prints an error message `The
binary log <name> is shorter than its expected size'. In this case,
this binary log is not correct and replication should be restarted from
a fresh snapshot of the master's data.

For MySQL 5.1.20 and later (and MySQL 5.0.46 and later for backward
compatibility), the following session variables are written to the
binary log and honored by the replication slave when parsing the binary
log:

   * `SQL_MODE'

   * `FOREIGN_KEY_CHECKS'

   * `UNIQUE_CHECKS'

   * `CHARACTER_SET_CLIENT'

   * `COLLATION_CONNECTION'

   * `COLLATION_DATABASE'

   * `COLLATION_SERVER'

   * `SQL_AUTO_IS_NULL'


File: manual.info,  Node: binary-log-formats,  Next: binary-log-setting,  Prev: binary-log,  Up: binary-log

5.2.4.1 Binary Logging Formats
..............................

A number of different logging formats are used to record information in
the binary log. The exact format employed depends on the version of
MySQL being used. There are three logging formats:

   * Replication capabilities in MySQL originally were based on
     propagation of SQL statements from master to slave. This is called
     _statement-based logging_.  You can cause this format to be used
     by starting the server with `--binlog-format=STATEMENT'.

   * In _row-based logging_, the master writes events to the binary log
     that indicate how individual table rows are affected. You can
     cause the server to use row-based logging by starting it with
     `--binlog-format=ROW'.

     Support for row-based logging was added in MySQL 5.1.5.

   * A third option is also available: _mixed logging_. With mixed
     logging, statement-based logging is used by default, but the
     logging mode switches automatically to row-based in certain cases
     as described below. You can cause MySQL to use mixed logging
     explicitly by starting `mysqld' with the option
     `--binlog-format=MIXED'.

     Mixed logging is available beginning with MySQL 5.1.8.  Beginning
     with MySQL 5.1.12, it is the default logging mode.

     Starting with MySQL 5.1.20, the logging format can also be set or
     limited by the storage engine being used. This helps to eliminate
     issues when logging, and more specifically replicating, certain
     statements between a master and slave which are using different
     storage engines.


File: manual.info,  Node: binary-log-setting,  Next: binary-log-mixed,  Prev: binary-log-formats,  Up: binary-log

5.2.4.2 Setting The Binary Log Format
.....................................

The default binary logging format depends on the version of MySQL you
are using:

   * For MySQL 5.1.11 and earlier, statement-based logging is used by
     default.

   * For MySQL 5.1.12 and later, mixed logging is used by default.

You can force the replication format by starting the MySQL server with
`--binlog-format=TYPE'.  When set, all replication slaves connecting to
the server will read the events according to this setting. The supported
values for TYPE are:

   * `ROW' causes replication to be row-based.

   * `STATEMENT' causes replication to be statement-based. This is the
     default for MySQL 5.1.11 and earlier.

   * `MIXED' causes replication to use mixed format. This is the
     default for MySQL 5.1.12 and later.

The logging format also can be switched at runtime. To specify the
format globally for all clients, set the global value of the
`binlog_format' system variable. (To change a global variable you need
the `SUPER' privilege.)

To switch to statement-based format, use either of these statements:

     mysql> SET GLOBAL binlog_format = 'STATEMENT';
     mysql> SET GLOBAL binlog_format = 1;

To switch to row-based format, use either of these statements:

     mysql> SET GLOBAL binlog_format = 'ROW';
     mysql> SET GLOBAL binlog_format = 2;

To switch to mixed format, use either of these statements:

     mysql> SET GLOBAL binlog_format = 'MIXED';
     mysql> SET GLOBAL binlog_format = 3;

An individual client can control the logging format for its own
statements by setting the session value of `binlog_format'. For example:

     mysql> SET SESSION binlog_format = 'STATEMENT';
     mysql> SET SESSION binlog_format = 'ROW';
     mysql> SET SESSION binlog_format = 'MIXED';

In addition to switching the logging format manually, a slave server
may switch the format _automatically_. This happens when the server is
running in either `STATEMENT' or `MIXED' format and encounters a row in
the binary log that is written in `ROW' logging format. In that case,
the slave switches to row-based replication temporarily for that event,
and switches back to the previous format afterwards.

There are two reasons why you might want to set replication logging on
a per-connection basis:

   * A thread that makes many small changes to the database might want
     to use row-based logging. A thread that performs updates that
     match many rows in the `WHERE' clause might want to use
     statement-based logging because it will be more efficient to log a
     few statements than many rows.

   * Some statements require a lot of execution time on the master, but
     result in just a few rows being modified. It might therefore be
     beneficial to replicate them using row-based logging.

There are exceptions when you cannot switch the replication format at
runtime:

   * From within a stored function or a trigger.

   * If `NDB' is enabled.

   * If the session is currently in row-based replication mode and has
     open temporary tables.

Trying to switch the format in any of these cases results in an error.

Switching the replication format at runtime is not recommended when any
temporary tables exist, because temporary tables are logged only when
using statement-based replication, whereas with row-based replication
they are not logged. With mixed replication, temporary tables are
usually logged; exceptions happen with user-defined functions (UDFs)
and with the `UUID()' function.

With the binlog format set to `ROW', many changes are written to the
binary log using the row-based format. Some changes, however, still use
the statement-based format. Examples include all DDL (data definition
language) statements such as `CREATE TABLE', `ALTER TABLE', or `DROP
TABLE'.

The `--binlog-row-event-max-size' option is available for servers that
are capable of row-based replication. Rows are stored into the binary
log in chunks having a size in bytes not exceeding the value of this
option.  The value must be a multiple of 256. The default value is 1024.

*Warning*:

When using _statement-based logging_ in a replication scenario, it is
possible for the data on the master and slave to become different if a
statement is designed in such a way that the data modification is
_non-deterministic_; that is, it is left to the will of the query
optimizer. In general, this is not a good practice even outside of
replication. For a detailed explanation of this issue, see *Note
open-bugs::.


File: manual.info,  Node: binary-log-mixed,  Next: binary-log-mysql-database,  Prev: binary-log-setting,  Up: binary-log

5.2.4.3 Mixed Binary Logging Format
...................................

When running in `MIXED' mode, automatic switching from statement-based
to row-based replication takes place under the following conditions:

   * When a DML statement updates an `NDB' table

   * When a function contains `UUID()'

   * When 2 or more tables with `AUTO_INCREMENT' columns are updated

   * When any `INSERT DELAYED' is executed

   * When the body of a view requires row-based replication, the
     statement creating the view also uses it -- for example, this
     occurs when the statement creating a view uses the `UUID()'
     function

   * When a call to a UDF is involved

   * If a statement is logged by row and the client that executed the
     statement has any temporary tables, then logging by row is used
     for all subsequent statements (except for those accessing
     temporary tables) until all temporary tables in use by that client
     are dropped

     This is true whether or not any temporary tables are actually
     logged

     Temporary tables cannot be logged using the row-based format;
     thus, once row-based logging is used, all subsequent statements
     using that table are unsafe, and we approximate this condition by
     treating all statements made by that client as unsafe until the
     client no longer holds any temporary tables

   * Beginning with MySQL 5.1.23:

        * When `FOUND_ROWS()' or `ROW_COUNT()' is used (Bug#12092
          (http://bugs.mysql.com/12092), Bug#30244
          (http://bugs.mysql.com/30244))

        * When `USER()', `CURRENT_USER()', or `CURRENT_USER' is used
          (Bug#28086 (http://bugs.mysql.com/28086))

        * Beginning with MySQL MySQL 5.1.24, when a statement refers to
          one or more system variables. (Bug#31168
          (http://bugs.mysql.com/31168))

*Note*:

Starting with MySQL 5.1.20 a warning is generated if you try to log
execute a statement in statement-logging mode that should be logged in
row-logging mode. The warning is shown both in the client (in the
output of `SHOW WARNINGS') and through the `mysqld' error log. A
warning is added to the `SHOW WARNINGS' table each time a statement is
executed. However, only the first statement that generated the warning
for each client session is logged to the `mysqld' error log to prevent
flooding the error log.

Starting with MySQL 5.1.20, in addition to the decisions above,
individual engines can also determine the logging format used when
information in a table is updated. The following table lists the
logging formats supported by each storage engine:

Storage Engine                       Row Logging        Statement Logging
                                     Supported          Supported
`ARCHIVE'                            Yes                Yes
`BLACKHOLE'                          No                 Yes
`CSV'                                Yes                Yes
`EXAMPLE'                            Yes                No
`FEDERATED'                          Yes                Yes
`HEAP'                               Yes                Yes
`InnoDB'                             Yes                Yes
`MyISAM'                             Yes                Yes
`MERGE'                              Yes                Yes
`NDB'                                Yes                No

A given storage engine can support either or both logging formats; the
logging capabilities of an individual engine can be further defined as
follows:

   * If an engine supports row-based logging, then the engine is said
     to be _row-logging capable_.

   * If an engine supports statement-based logging, then the engine is
     said to be _statement-logging capable_.

When determining the logging mode to be used, the capabilities of all
the tables affected by the event are combined. The set of affected
tables is then marked according to these rules:

   * A set of tables is defined as _row logging restricted_ if the
     tables are row logging capable but not statement logging capable.

   * A set of tables is defined as _statement logging restricted_ if
     the tables are statement logging capable but not row logging
     capable.

Once the determination of the possible logging formats required by the
statement is complete it is compared to the current `BINLOG_FORMAT'
setting. The following table is used to decide how the information is
recorded in the binary log or, if appropriate, whether an error is
raised. In the table, a safe operation is defined as one that is
deterministic. A number of rules decide whether the statement is
deterministic or not, as shown in the following table (where *RLC*
stands for `row-logging capable' and *SLC* stands for
`statement-logging capable'):

ConditionAction                                            
Safe/unsafe`BINLOG_FORMAT'    RLC     SLC     Error/Warning  Logged as
Safe    STATEMENT          N       N       Error: not     
                                           loggable       
Safe    STATEMENT          N       Y                      STATEMENT
Safe    STATEMENT          Y       N       Error: not     
                                           loggable       
Safe    STATEMENT          Y       Y                      STATEMENT
Safe    MIXED              N       N       Error: not     
                                           loggable       
Safe    MIXED              N       Y                      STATEMENT
Safe    MIXED              Y       N                      ROW
Safe    MIXED              Y       Y                      STATEMENT
Safe    ROW                N       N       Error: not     
                                           loggable       
Safe    ROW                N       Y       Error: not     
                                           loggable       
Safe    ROW                Y       N                      ROW
Safe    ROW                Y       Y                      ROW
Unsafe  STATEMENT          N       N       Error: not     
                                           loggable       
Unsafe  STATEMENT          N       Y       Warning:       STATEMENT
                                           unsafe         
Unsafe  STATEMENT          Y       N       Error: not     
                                           loggable       
Unsafe  STATEMENT          Y       Y       Warning:       STATEMENT
                                           unsafe         
Unsafe  MIXED              N       N       Error: not     
                                           loggable       
Unsafe  MIXED              N       Y       Error: not     
                                           loggable       
Unsafe  MIXED              Y       N                      ROW
Unsafe  MIXED              Y       Y                      ROW
Unsafe  ROW                N       N       Error: not     
                                           loggable       
Unsafe  ROW                N       Y       Error: not     
                                           loggable       
Unsafe  ROW                Y       N                      ROW
Unsafe  ROW                Y       Y                      ROW

When a warning is produced by the determination, a standard MySQL
warning is produced (and is available using `SHOW WARNINGS'). The
information is also written to the `mysqld' error log. Only one error
for each error instance per client connection is logged.  The log
message will include the SQL statement that was attempted.


File: manual.info,  Node: binary-log-mysql-database,  Prev: binary-log-mixed,  Up: binary-log

5.2.4.4 Logging Format for Changes to `mysql' Database Tables
.............................................................

The contents of the grant tables in the `mysql' database can be
modified directly (for example, with `INSERT' or `DELETE') or
indirectly (for example, with `GRANT' or `CREATE USER').  As of MySQL
5.1.17, statements that affect `mysql' database tables are written to
the binary log using the following rules:

   * Data manipulation statements that change data in `mysql' database
     tables directly are logged according to the setting of the
     `binlog_format' system variable. This pertains to statements such
     as `INSERT', `UPDATE', `DELETE', `REPLACE', `DO', `LOAD DATA
     INFILE', `SELECT', and `TRUNCATE'.

   * Statements that change the `mysql' database indirectly are logged
     as statements regardless of the value of `binlog_format'. This
     pertains to statements such as `GRANT', `REVOKE', `SET PASSWORD',
     `RENAME USER', `CREATE' (all forms except `CREATE TABLE ...
     SELECT'), `ALTER' (all forms), and `DROP' (all forms).

`CREATE TABLE ... SELECT' is a combination of data definition and data
manipulation. The `CREATE TABLE' part is logged using statement format
and the `SELECT' part is logged according to the value of
`binlog_format'.


File: manual.info,  Node: slow-query-log,  Next: log-file-maintenance,  Prev: binary-log,  Up: log-files

5.2.5 The Slow Query Log
------------------------

The slow query log consists of all SQL statements that took more than
`long_query_time' seconds to execute and (as of MySQL 5.1.21) required
at least `min_examined_row_limit' rows to be examined.  The time to
acquire the initial table locks is not counted as execution time.
`mysqld' writes a statement to the slow query log after it has been
executed and after all locks have been released, so log order might be
different from execution order. The minimum and default values of
`long_query_time' are 1 and 10, respectively.  Prior to MySQL 5.1.21,
the minimum value is 1, and the value for this variable must be an
integer. Beginning with MySQL 5.1.21, the minimum is 0, and a
resolution of microseconds is supported when logging to a file.
However, the microseconds part is ignored and only integer values are
written when logging to tables.

To enable the slow query log as of MySQL 5.1.6, start `mysqld' with the
`--log-slow-queries[=FILE_NAME]' option, and optionally use
`--log-output' to specify the log destination (as described in *Note
log-tables::). Before 5.1.6, the slow query log destination is always a
file. To enable the slow query log file, use the
`--log-slow-queries[=FILE_NAME]' option.

If no FILE_NAME value is given for `--log-slow-queries', the default
name is `HOST_NAME-slow.log'.  If a filename is given, but not as an
absolute pathname, the server writes the file in the data directory.

When `--log-slow-queries' is specified, the `--slow-query-log' option
also may be given as of MySQL 5.1.12 to specify the initial slow query
log state. With no argument or an argument of 0, the option disables
the log. If omitted or given with an argument of 1, the option enables
the log. If `--log--slow-queries' is not given, `--slow-query-log' has
no effect.

The global `slow_query_log' and `slow_query_log_file' system variables
provide runtime control over the slow query log. Set `slow_query_log'
to 0 (or `OFF') to disable the log or to 1 (or `ON') to enable it. Set
`general_log_file' to specify the name of the log file. If a log file
already is open, it is closed and the new file is opened.

When the slow query log is enabled, output is written to any
destinations specified by the `--log-output' option or `log_output'
system variable. Note that if the destination is `NONE', no output is
written even if the slow query log is enabled. Setting the log filename
has no effect on logging if the log destination value does not contain
`FILE'.

The slow query log can be used to find queries that take a long time to
execute and are therefore candidates for optimization.  However,
examining a long slow query log can become a difficult task. To make
this easier, you can process the slow query log using the
`mysqldumpslow' command to summarize the queries that appear in the
log. Use `mysqldumpslow --help' to see the options that this command
supports.

In MySQL 5.1, queries that do not use indexes are logged in the slow
query log if the `--log-queries-not-using-indexes' option is specified.
See *Note server-options::.

MySQL Enterprise

Excessive table scans are indicative of missing or poorly optimized
indexes. Using an advisor specifically designed for the task, the MySQL
Enterprise Monitor can identify such problems and offer advice on
resolution. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

In MySQL 5.1, the `--log-slow-admin-statements' server option enables
you to request logging of slow administrative statements such as
`OPTIMIZE TABLE', `ANALYZE TABLE', and `ALTER TABLE' to the slow query
log.

Queries handled by the query cache are not added to the slow query log,
nor are queries that would not benefit from the presence of an index
because the table has zero rows or one row.


File: manual.info,  Node: log-file-maintenance,  Prev: slow-query-log,  Up: log-files

5.2.6 Server Log Maintenance
----------------------------

MySQL Server can create a number of different log files that make it
easy to see what is going on. See *Note log-files::. However, you must
clean up these files regularly to ensure that the logs do not take up
too much disk space.

When using MySQL with logging enabled, you may want to back up and
remove old log files from time to time and tell MySQL to start logging
to new files. See *Note backup::.

On a Linux (Red Hat) installation, you can use the `mysql-log-rotate'
script for this. If you installed MySQL from an RPM distribution, this
script should have been installed automatically. You should be careful
with this script if you are using the binary log for replication. You
should not remove binary logs until you are certain that their contents
have been processed by all slaves.

On other systems, you must install a short script yourself that you
start from `cron' (or its equivalent) for handling log files.

For the binary log, you can set the `expire_logs_days' system variable
to expire binary log files automatically after a given number of days
(see *Note server-system-variables::). If you are using replication,
you should set the variable no lower than the maximum number of days
your slaves might lag behind the master.

You can force MySQL to start using new log files by issuing a `FLUSH
LOGS' statement or executing `mysqladmin flush-logs' or `mysqladmin
refresh'. See *Note flush::, and *Note mysqladmin::.

A log flushing operation does the following:

   * If general query logging (`--log') or slow query logging
     (`--log-slow-queries') to a log file is enabled, the server closes
     and reopens the general query log file or slow query log file.

   * If binary logging (`--log-bin') is used, the server closes the
     current log file and opens a new log file with the next sequence
     number.

   * If the server was given an error log filename with the
     `--log-error' option, it renames the error log with the suffix
     `-old' and creates a new empty error log file.

The server creates a new binary log file when you flush the logs.
However, it just closes and reopens the general and slow query log
files. To cause new files to be created on Unix, rename the current
logs before flushing them. At flush time, the server will open new logs
with the original names. For example, if the general and slow query
logs are named `mysql.log' and `mysql-slow.log', you can use a series of
commands like this:

     shell> cd MYSQL-DATA-DIRECTORY
     shell> mv mysql.log mysql.old
     shell> mv mysql-slow.log mysql-slow.old
     shell> mysqladmin flush-logs

At this point, you can make a backup of `mysql.old' and
`mysql-slow.log' and then remove them from disk.

Before 5.1.3, you cannot rename a log file on Windows while the server
has it open. You must stop the server and rename the file, and then
restart the server to create a new log file. As of 5.1.3, this applies
only to the error log. However, a stop and restart can be avoided by
using `FLUSH LOGS', which causes the server to rename the error log
with an `-old' suffix and open a new error log.

As of MySQL 5.1.2, you can disable the general query log or slow query
log at runtime:

     SET GLOBAL general_log = 'OFF';
     SET GLOBAL slow_query_log = 'OFF';

With the logs disabled, rename the log files externally; for example,
from the command line. Then enable the logs again:

     SET GLOBAL general_log = 'ON';
     SET GLOBAL slow_query_log = 'ON';

This method works on any platform and does not require a server restart.


File: manual.info,  Node: security,  Next: privilege-system,  Prev: log-files,  Up: server-administration

5.3 General Security Issues
===========================

* Menu:

* security-guidelines::          General Security Guidelines
* security-against-attack::      Making MySQL Secure Against Attackers
* privileges-options::           Security-Related `mysqld' Options
* load-data-local::              Security Issues with `LOAD DATA LOCAL'
* changing-mysql-user::          How to Run MySQL as a Normal User

This section describes some general security issues to be aware of and
what you can do to make your MySQL installation more secure against
attack or misuse. For information specifically about the access control
system that MySQL uses for setting up user accounts and checking
database access, see *Note privilege-system::.

For answers to some questions that are often asked about MySQL Server
security issues, see *Note faqs-security::.


File: manual.info,  Node: security-guidelines,  Next: security-against-attack,  Prev: security,  Up: security

5.3.1 General Security Guidelines
---------------------------------

Anyone using MySQL on a computer connected to the Internet should read
this section to avoid the most common security mistakes.

In discussing security, we emphasize the necessity of fully protecting
the entire server host (not just the MySQL server) against all types of
applicable attacks: eavesdropping, altering, playback, and denial of
service. We do not cover all aspects of availability and fault
tolerance here.

MySQL uses security based on Access Control Lists (ACLs) for all
connections, queries, and other operations that users can attempt to
perform. There is also support for SSL-encrypted connections between
MySQL clients and servers. Many of the concepts discussed here are not
specific to MySQL at all; the same general ideas apply to almost all
applications.

When running MySQL, follow these guidelines whenever possible:

   * *Do not ever give anyone (except MySQL `root' accounts) access to
     the `user' table in the `mysql' database!* This is critical.

   * Learn the MySQL access privilege system. The `GRANT' and `REVOKE'
     statements are used for controlling access to MySQL. Do not grant
     more privileges than necessary. Never grant privileges to all
     hosts.

     Checklist:

        * Try `mysql -u root'. If you are able to connect successfully
          to the server without being asked for a password, anyone can
          connect to your MySQL server as the MySQL `root' user with
          full privileges! Review the MySQL installation instructions,
          paying particular attention to the information about setting
          a `root' password. See *Note default-privileges::.

        * Use the `SHOW GRANTS' statement to check which accounts have
          access to what. Then use the `REVOKE' statement to remove
          those privileges that are not necessary.

   * Do not store any plain-text passwords in your database. If your
     computer becomes compromised, the intruder can take the full list
     of passwords and use them. Instead, use `MD5()', `SHA1()', or some
     other one-way hashing function and store the hash value.

   * Do not choose passwords from dictionaries. Special programs exist
     to break passwords. Even passwords like `xfish98' are very bad.
     Much better is `duag98' which contains the same word `fish' but
     typed one key to the left on a standard QWERTY keyboard. Another
     method is to use a password that is taken from the first
     characters of each word in a sentence (for example, `Mary had a
     little lamb' results in a password of `Mhall').  The password is
     easy to remember and type, but difficult to guess for someone who
     does not know the sentence.

   * Invest in a firewall. This protects you from at least 50% of all
     types of exploits in any software. Put MySQL behind the firewall
     or in a demilitarized zone (DMZ).

     Checklist:

        * Try to scan your ports from the Internet using a tool such as
          `nmap'. MySQL uses port 3306 by default. This port should not
          be accessible from untrusted hosts. Another simple way to
          check whether or not your MySQL port is open is to try the
          following command from some remote machine, where SERVER_HOST
          is the hostname or IP number of the host on which your MySQL
          server runs:

               shell> telnet SERVER_HOST 3306

          If you get a connection and some garbage characters, the port
          is open, and should be closed on your firewall or router,
          unless you really have a good reason to keep it open. If
          `telnet' hangs or the connection is refused, the port is
          blocked, which is how you want it to be.

   * Do not trust any data entered by users of your applications.  They
     can try to trick your code by entering special or escaped
     character sequences in Web forms, URLs, or whatever application
     you have built. Be sure that your application remains secure if a
     user enters something like ``; DROP DATABASE mysql;''.  This is an
     extreme example, but large security leaks and data loss might
     occur as a result of hackers using similar techniques, if you do
     not prepare for them.

     A common mistake is to protect only string data values.  Remember
     to check numeric data as well. If an application generates a query
     such as `SELECT * FROM table WHERE ID=234' when a user enters the
     value `234', the user can enter the value `234 OR 1=1' to cause
     the application to generate the query `SELECT * FROM table WHERE
     ID=234 OR 1=1'. As a result, the server retrieves every row in the
     table. This exposes every row and causes excessive server load.
     The simplest way to protect from this type of attack is to use
     single quotes around the numeric constants: `SELECT * FROM table
     WHERE ID='234''. If the user enters extra information, it all
     becomes part of the string. In a numeric context, MySQL
     automatically converts this string to a number and strips any
     trailing non-numeric characters from it.

     Sometimes people think that if a database contains only publicly
     available data, it need not be protected. This is incorrect. Even
     if it is allowable to display any row in the database, you should
     still protect against denial of service attacks (for example,
     those that are based on the technique in the preceding paragraph
     that causes the server to waste resources). Otherwise, your server
     becomes unresponsive to legitimate users.

     Checklist:

        * Try to enter single and double quote marks (``''' and ``"'')
          in all of your Web forms. If you get any kind of MySQL error,
          investigate the problem right away.

        * Try to modify dynamic URLs by adding `%22' (``"''), `%23'
          (``#''), and `%27' (``''') to them.

        * Try to modify data types in dynamic URLs from numeric to
          character types using the characters shown in the previous
          examples. Your application should be safe against these and
          similar attacks.

        * Try to enter characters, spaces, and special symbols rather
          than numbers in numeric fields. Your application should
          remove them before passing them to MySQL or else generate an
          error. Passing unchecked values to MySQL is very dangerous!

        * Check the size of data before passing it to MySQL.

        * Have your application connect to the database using a
          username different from the one you use for administrative
          purposes. Do not give your applications any access privileges
          they do not need.

   * Many application programming interfaces provide a means of
     escaping special characters in data values. Properly used, this
     prevents application users from entering values that cause the
     application to generate statements that have a different effect
     than you intend:

        * MySQL C API: Use the *Note `mysql_real_escape_string()':
          mysql-real-escape-string.  API call.

        * MySQL++: Use the `escape' and `quote' modifiers for query
          streams.

        * PHP: Use the `mysql_real_escape_string()' function (available
          as of PHP 4.3.0, prior to that PHP version use
          `mysql_escape_string()', and prior to PHP 4.0.3, use
          `addslashes()' ). Note that only `mysql_real_escape_string()'
          is character set-aware; the other functions can be `bypassed'
          when using (invalid) multi-byte character sets. In PHP 5, you
          can use the `mysqli' extension, which supports the improved
          MySQL authentication protocol and passwords, as well as
          prepared statements with placeholders.

        * Perl DBI: Use placeholders or the `quote()' method.

        * Ruby DBI: Use placeholders or the `quote()' method.

        * Java JDBC: Use a `PreparedStatement' object and placeholders.

     Other programming interfaces might have similar capabilities.

   * Do not transmit plain (unencrypted) data over the Internet.  This
     information is accessible to everyone who has the time and ability
     to intercept it and use it for their own purposes. Instead, use an
     encrypted protocol such as SSL or SSH. MySQL supports internal SSL
     connections as of version 4.0. Another technique is to use SSH
     port-forwarding to create an encrypted (and compressed) tunnel for
     the communication.

   * Learn to use the `tcpdump' and `strings' utilities. In most cases,
     you can check whether MySQL data streams are unencrypted by issuing
     a command like the following:

          shell> tcpdump -l -i eth0 -w - src or dst port 3306 | strings

     This works under Linux and should work with small modifications
     under other systems.

     *Warning*:

     If you do not see plaintext data, this does not always mean that
     the information actually is encrypted. If you need high security,
     you should consult with a security expert.


File: manual.info,  Node: security-against-attack,  Next: privileges-options,  Prev: security-guidelines,  Up: security

5.3.2 Making MySQL Secure Against Attackers
-------------------------------------------

When you connect to a MySQL server, you should use a password.  The
password is not transmitted in clear text over the connection. Password
handling during the client connection sequence was upgraded in MySQL
4.1.1 to be very secure. If you are still using pre-4.1.1-style
passwords, the encryption algorithm is not as strong as the newer
algorithm. With some effort, a clever attacker who can sniff the
traffic between the client and the server can crack the password. (See
*Note password-hashing::, for a discussion of the different password
handling methods.)

MySQL Enterprise

The MySQL Enterprise Monitor enforces best practices for maximizing the
security of your servers. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

All other information is transferred as text, and can be read by anyone
who is able to watch the connection. If the connection between the
client and the server goes through an untrusted network, and you are
concerned about this, you can use the compressed protocol to make
traffic much more difficult to decipher. You can also use MySQL's
internal SSL support to make the connection even more secure. See *Note
secure-connections::. Alternatively, use SSH to get an encrypted TCP/IP
connection between a MySQL server and a MySQL client. You can find an
Open Source SSH client at `http://www.openssh.org/', and a commercial
SSH client at `http://www.ssh.com/'.

To make a MySQL system secure, you should strongly consider the
following suggestions:

   * Require all MySQL accounts to have a password. A client program
     does not necessarily know the identity of the person running it.
     It is common for client/server applications that the user can
     specify any username to the client program. For example, anyone
     can use the `mysql' program to connect as any other person simply
     by invoking it as `mysql -u OTHER_USER DB_NAME' if OTHER_USER has
     no password. If all accounts have a password, connecting using
     another user's account becomes much more difficult.

     For a discussion of methods for setting passwords, see *Note
     passwords::.

   * Never run the MySQL server as the Unix `root' user. This is
     extremely dangerous, because any user with the `FILE' privilege is
     able to cause the server to create files as `root' (for example,
     `~root/.bashrc'). To prevent this, `mysqld' refuses to run as
     `root' unless that is specified explicitly using the `--user=root'
     option.

     `mysqld' can (and should) be run as an ordinary, unprivileged user
     instead. You can create a separate Unix account named `mysql' to
     make everything even more secure. Use this account only for
     administering MySQL. To start `mysqld' as a different Unix user,
     add a `user' option that specifies the username in the `[mysqld]'
     group of the `my.cnf' option file where you specify server
     options. For example:

          [mysqld]
          user=mysql

     This causes the server to start as the designated user whether you
     start it manually or by using `mysqld_safe' or `mysql.server'. For
     more details, see *Note changing-mysql-user::.

     Running `mysqld' as a Unix user other than `root' does not mean
     that you need to change the `root' username in the `user' table.
     _Usernames for MySQL accounts have nothing to do with usernames
     for Unix accounts_.

   * Do not allow the use of symlinks to tables. (This capability can
     be disabled with the `--skip-symbolic-links' option.) This is
     especially important if you run `mysqld' as `root', because anyone
     that has write access to the server's data directory then could
     delete any file in the system! See *Note
     symbolic-links-to-tables::.

   * Make sure that the only Unix user account with read or write
     privileges in the database directories is the account that is used
     for running `mysqld'.

   * Do not grant the `PROCESS' or `SUPER' privilege to
     non-administrative users. The output of `mysqladmin processlist'
     and `SHOW PROCESSLIST' shows the text of any statements currently
     being executed, so any user who is allowed to see the server
     process list might be able to see statements issued by other users
     such as `UPDATE user SET password=PASSWORD('not_secure')'.

     `mysqld' reserves an extra connection for users who have the
     `SUPER' privilege, so that a MySQL `root' user can log in and
     check server activity even if all normal connections are in use.

     The `SUPER' privilege can be used to terminate client connections,
     change server operation by changing the value of system variables,
     and control replication servers.

   * Do not grant the `FILE' privilege to non-administrative users. Any
     user that has this privilege can write a file anywhere in the
     filesystem with the privileges of the `mysqld' daemon. To make
     this a bit safer, files generated with `SELECT ...  INTO OUTFILE'
     do not overwrite existing files and are writable by everyone.

     The `FILE' privilege may also be used to read any file that is
     world-readable or accessible to the Unix user that the server runs
     as. With this privilege, you can read any file into a database
     table. This could be abused, for example, by using `LOAD DATA' to
     load `/etc/passwd' into a table, which then can be displayed with
     `SELECT'.

   * If you do not trust your DNS, you should use IP numbers rather
     than hostnames in the grant tables. In any case, you should be
     very careful about creating grant table entries using hostname
     values that contain wildcards.

   * If you want to restrict the number of connections allowed to a
     single account, you can do so by setting the
     `max_user_connections' variable in `mysqld'. The `GRANT' statement
     also supports resource control options for limiting the extent of
     server use allowed to an account. See *Note grant::.


File: manual.info,  Node: privileges-options,  Next: load-data-local,  Prev: security-against-attack,  Up: security

5.3.3 Security-Related `mysqld' Options
---------------------------------------

The following `mysqld' options affect security:

*Name*                        *Cmd-Line*                                                 *Option file*                                              *System Var*                                               *Status Var*                                               *Var Scope*                                                *Dynamic*
allow-suspicious-udfs         Yes                                                        Yes                                                                                                                                                                                                                                         
automatic_sp_privileges                                                                                                                             Yes                                                                                                                   Global                                                     Yes
chroot                        Yes                                                        Yes                                                                                                                                                                                                                                         
des-key-file                  Yes                                                        Yes                                                                                                                                                                                                                                         
local_infile                                                                                                                                        Yes                                                                                                                   Global                                                     Yes
local-infile                  Yes                                                        Yes                                                                                                                                                                                                                                         
old-passwords                 Yes                                                        Yes                                                                                                                                                                              Both                                                       Yes
- _Variable_: old_passwords                                                                                                                         Yes                                                                                                                   Both                                                       Yes
safe-user-create              Yes                                                        Yes                                                                                                                                                                                                                                         
secure-auth                   Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: secure_auth                                                                                                                           Yes                                                                                                                   Global                                                     Yes
secure-file-priv              Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
secure_file_priv                                                                                                                                                                                                                                                                                                                     
skip-grant-tables             Yes                                                        Yes                                                                                                                                                                                                                                         
skip-name-resolve             Yes                                                        Yes                                                                                                                                                                                                                                         
skip-networking               Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: skip_networking                                                                                                                       Yes                                                                                                                   Global                                                     No
skip-show-database            Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
skip_show_database                                                                                                                                                                                                                                                                                                                   

   * `--allow-suspicious-udfs'

     This option controls whether user-defined functions that have only
     an `xxx' symbol for the main function can be loaded. By default,
     the option is off and only UDFs that have at least one auxiliary
     symbol can be loaded; this prevents attempts at loading functions
     from shared object files other than those containing legitimate
     UDFs. See *Note udf-security::.

   *  `--local-infile[={0|1}]'

     If you start the server with `--local-infile=0', clients cannot use
     `LOCAL' in `LOAD DATA' statements. See *Note load-data-local::.

   * `--old-passwords'

     Force the server to generate short (pre-4.1) password hashes for
     new passwords. This is useful for compatibility when the server
     must support older client programs. See *Note password-hashing::.

     MySQL Enterprise

     The MySQL Enterprise Monitor offers advice on the security
     implications of using this option. For subscription information see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   * `--safe-show-database' (_OBSOLETE_)

     In previous versions of MySQL, this option caused the `SHOW
     DATABASES' statement to display the names of only those databases
     for which the user had some kind of privilege. In MySQL 5.1, this
     option is no longer available as this is now the default behavior,
     and there is a `SHOW DATABASES' privilege that can be used to
     control access to database names on a per-account basis. See *Note
     grant::.

   * `--safe-user-create'

     If this option is enabled, a user cannot create new MySQL users by
     using the `GRANT' statement unless the user has the `INSERT'
     privilege for the `mysql.user' table or any column in the table.
     If you want a user to have the ability to create new users that
     have those privileges that the user has the right to grant, you
     should grant the user the following privilege:

          GRANT INSERT(user) ON mysql.user TO 'USER_NAME'@'HOST_NAME';

     This ensures that the user cannot change any privilege columns
     directly, but has to use the `GRANT' statement to give privileges
     to other users.

   * `--secure-auth'

     Disallow authentication for accounts that have old (pre-4.1)
     passwords.

     The `mysql' client also has a `--secure-auth' option, which
     prevents connections to a server if the server requires a password
     in old format for the client account.

   * `--secure-file-priv=PATH'

     This option limits the effect of the `LOAD_FILE()' function and the
     `LOAD DATA' and `SELECT ... INTO OUTFILE' statements to work only
     with files in the specified directory.

     This option was added in MySQL 5.1.17.

   * `--skip-grant-tables'

     This option causes the server not to use the privilege system at
     all. This gives anyone with access to the server _unrestricted
     access_ to _all databases_. You can cause a running server to
     start using the grant tables again by executing `mysqladmin
     flush-privileges' or `mysqladmin reload' command from a system
     shell, or by issuing a MySQL `FLUSH PRIVILEGES' statement. This
     option also suppresses loading of plugins and user-defined
     functions (UDFs).

   *  `--skip-merge'

     Disable the `MERGE' storage engine. This option was added in MySQL
     5.1.12. It can be used if the following behavior is undesirable:
     If a user has access to `MyISAM' table T, that user can create a
     `MERGE' table M that accesses T. However, if the user's privileges
     on T are subsequently revoked, the user can continue to access T
     by doing so through M.

   * `--skip-name-resolve'

     Hostnames are not resolved. All `Host' column values in the grant
     tables must be IP numbers or `localhost'.

   * `--skip-networking'

     Do not allow TCP/IP connections over the network. All connections
     to `mysqld' must be made via Unix socket files.

   * `--skip-show-database'

     With this option, the `SHOW DATABASES' statement is allowed only
     to users who have the `SHOW DATABASES' privilege, and the
     statement displays all database names. Without this option, `SHOW
     DATABASES' is allowed to all users, but displays each database
     name only if the user has the `SHOW DATABASES' privilege or some
     privilege for the database. Note that any global privilege is a
     privilege for the database.

   *  `--ssl*'

     Options that begin with `--ssl' specify whether to allow clients
     to connect via SSL and indicate where to find SSL keys and
     certificates. See *Note ssl-options::.


File: manual.info,  Node: load-data-local,  Next: changing-mysql-user,  Prev: privileges-options,  Up: security

5.3.4 Security Issues with `LOAD DATA LOCAL'
--------------------------------------------

The `LOAD DATA' statement can load a file that is located on the server
host, or it can load a file that is located on the client host when the
`LOCAL' keyword is specified.

There are two potential security issues with supporting the `LOCAL'
version of `LOAD DATA' statements:

   * The transfer of the file from the client host to the server host
     is initiated by the MySQL server. In theory, a patched server
     could be built that would tell the client program to transfer a
     file of the server's choosing rather than the file named by the
     client in the `LOAD DATA' statement. Such a server could access
     any file on the client host to which the client user has read
     access.

   * In a Web environment where the clients are connecting from a Web
     server, a user could use `LOAD DATA LOCAL' to read any files that
     the Web server process has read access to (assuming that a user
     could run any command against the SQL server). In this environment,
     the client with respect to the MySQL server actually is the Web
     server, not the remote program being run by the user who connects
     to the Web server.

To deal with these problems, we changed how `LOAD DATA LOCAL' is
handled as of MySQL 3.23.49 and MySQL 4.0.2 (4.0.13 on Windows):

   * By default, all MySQL clients and libraries in binary
     distributions are compiled with the `--enable-local-infile'
     option, to be compatible with MySQL 3.23.48 and before.

   * If you build MySQL from source but do not invoke `configure' with
     the `--enable-local-infile' option, `LOAD DATA LOCAL' cannot be
     used by any client unless it is written explicitly to invoke *Note
     `mysql_options(... MYSQL_OPT_LOCAL_INFILE, 0)': mysql-options. See
     *Note mysql-options::.

   * You can disable all `LOAD DATA LOCAL' commands from the server
     side by starting `mysqld' with the `--local-infile=0' option.

   * For the `mysql' command-line client, `LOAD DATA LOCAL' can be
     enabled by specifying the `--local-infile[=1]' option, or disabled
     with the `--local-infile=0' option. Similarly, for `mysqlimport',
     the `--local' or `-L' option enables local data file loading. In
     any case, successful use of a local loading operation requires
     that the server is enabled to allow it.

   * If you use `LOAD DATA LOCAL' in Perl scripts or other programs
     that read the `[client]' group from option files, you can add the
     `local-infile=1' option to that group. However, to keep this from
     causing problems for programs that do not understand
     `local-infile', specify it using the `loose-' prefix:

          [client]
          loose-local-infile=1

   * If `LOAD DATA LOCAL INFILE' is disabled, either in the server or
     the client, a client that attempts to issue such a statement
     receives the following error message:

          ERROR 1148: The used command is not allowed with this MySQL version

MySQL Enterprise

Security advisors notify subscribers to the MySQL Enterprise Monitor
whenever a server is started with the `--local-infile' option enabled.
For more information see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: changing-mysql-user,  Prev: load-data-local,  Up: security

5.3.5 How to Run MySQL as a Normal User
---------------------------------------

On Windows, you can run the server as a Windows service using a normal
user account.

On Unix, the MySQL server `mysqld' can be started and run by any user.
However, you should avoid running the server as the Unix `root' user
for security reasons. To change `mysqld' to run as a normal
unprivileged Unix user USER_NAME, you must do the following:

  1. Stop the server if it's running (use `mysqladmin shutdown').

  2. Change the database directories and files so that USER_NAME has
     privileges to read and write files in them (you might need to do
     this as the Unix `root' user):

          shell> chown -R USER_NAME /PATH/TO/MYSQL/DATADIR

     If you do not do this, the server will not be able to access
     databases or tables when it runs as USER_NAME.

     If directories or files within the MySQL data directory are
     symbolic links, you'll also need to follow those links and change
     the directories and files they point to.  `chown -R' might not
     follow symbolic links for you.

  3. Start the server as user USER_NAME. If you are using MySQL 3.22 or
     later, another alternative is to start `mysqld' as the Unix `root'
     user and use the `--user=USER_NAME' option. `mysqld' starts up,
     then switches to run as the Unix user USER_NAME before accepting
     any connections.

  4. To start the server as the given user automatically at system
     startup time, specify the username by adding a `user' option to the
     `[mysqld]' group of the `/etc/my.cnf' option file or the `my.cnf'
     option file in the server's data directory. For example:

          [mysqld]
          user=USER_NAME

If your Unix machine itself isn't secured, you should assign passwords
to the MySQL `root' accounts in the grant tables. Otherwise, any user
with a login account on that machine can run the `mysql' client with a
`--user=root' option and perform any operation.  (It is a good idea to
assign passwords to MySQL accounts in any case, but especially so when
other login accounts exist on the server host.) See *Note
post-installation::.


File: manual.info,  Node: privilege-system,  Next: user-account-management,  Prev: security,  Up: server-administration

5.4 The MySQL Access Privilege System
=====================================

* Menu:

* what-privileges::              What the Privilege System Does
* privileges::                   How the Privilege System Works
* privileges-provided::          Privileges Provided by MySQL
* connection-access::            Access Control, Stage 1: Connection Verification
* request-access::               Access Control, Stage 2: Request Verification
* privilege-changes::            When Privilege Changes Take Effect
* access-denied::                Causes of `Access denied' Errors
* password-hashing::             Password Hashing as of MySQL 4.1

MySQL has an advanced but non-standard security and privilege system.
The following discussion describes how it works.


File: manual.info,  Node: what-privileges,  Next: privileges,  Prev: privilege-system,  Up: privilege-system

5.4.1 What the Privilege System Does
------------------------------------

The primary function of the MySQL privilege system is to authenticate a
user who connects from a given host and to associate that user with
privileges on a database such as `SELECT', `INSERT', `UPDATE', and
`DELETE'.

Additional functionality includes the ability to have anonymous users
and to grant privileges for MySQL-specific functions such as `LOAD DATA
INFILE' and administrative operations.


File: manual.info,  Node: privileges,  Next: privileges-provided,  Prev: what-privileges,  Up: privilege-system

5.4.2 How the Privilege System Works
------------------------------------

The MySQL privilege system ensures that all users may perform only the
operations allowed to them. As a user, when you connect to a MySQL
server, your identity is determined by _the host from which you
connect_ and _the username you specify_. When you issue requests after
connecting, the system grants privileges according to your identity and
_what you want to do_.

MySQL considers both your hostname and username in identifying you
because there is little reason to assume that a given username belongs
to the same person everywhere on the Internet.  For example, the user
`joe' who connects from `office.example.com' need not be the same
person as the user `joe' who connects from `home.example.com'. MySQL
handles this by allowing you to distinguish users on different hosts
that happen to have the same name: You can grant one set of privileges
for connections by `joe' from `office.example.com', and a different set
of privileges for connections by `joe' from `home.example.com'.

MySQL access control involves two stages when you run a client program
that connects to the server:

   * Stage 1: The server checks whether it should allow you to connect.

   * Stage 2: Assuming that you can connect, the server checks each
     statement you issue to determine whether you have sufficient
     privileges to perform it. For example, if you try to select rows
     from a table in a database or drop a table from the database, the
     server verifies that you have the `SELECT' privilege for the table
     or the `DROP' privilege for the database.

If your privileges are changed (either by yourself or someone else)
while you are connected, those changes do not necessarily take effect
immediately for the next statement that you issue.  See *Note
privilege-changes::, for details.

The server stores privilege information in the grant tables of the
`mysql' database (that is, in the database named `mysql'). The MySQL
server reads the contents of these tables into memory when it starts
and re-reads them under the circumstances indicated in *Note
privilege-changes::. Access-control decisions are based on the
in-memory copies of the grant tables.

Normally, you manipulate the contents of the grant tables indirectly by
using statements such as `GRANT' and `REVOKE' to set up accounts and
control the privileges available to each one. See *Note
account-management-sql::. The discussion here describes the underlying
structure of the grant tables and how the server uses their contents
when interacting with clients.

The server uses the `user', `db', and `host' tables in the `mysql'
database at both stages of access control. The columns in the `user' and
`db' tables are shown here. The `host' table is similar to the `db'
table but has a specialized use as described in *Note request-access::.

*Table Name*                  *user*                 *db*
*Scope columns*               `Host'                 `Host'
                              `User'                 `Db'
                              `Password'             `User'
*Privilege columns*           `Select_priv'          `Select_priv'
                              `Insert_priv'          `Insert_priv'
                              `Update_priv'          `Update_priv'
                              `Delete_priv'          `Delete_priv'
                              `Index_priv'           `Index_priv'
                              `Alter_priv'           `Alter_priv'
                              `Create_priv'          `Create_priv'
                              `Drop_priv'            `Drop_priv'
                              `Grant_priv'           `Grant_priv'
                              `Create_view_priv'     `Create_view_priv'
                              `Show_view_priv'       `Show_view_priv'
                              `Create_routine_priv'  `Create_routine_priv'
                              `Alter_routine_priv'   `Alter_routine_priv'
                              `Execute_priv'         `Execute_priv'
                              `Trigger_priv'         `Trigger_priv'
                              `Event_priv'           `Event_priv'
                              `Create_tmp_table_priv'`Create_tmp_table_priv'
                              `Lock_tables_priv'     `Lock_tables_priv'
                              `References_priv'      `References_priv'
                              `Reload_priv'          
                              `Shutdown_priv'        
                              `Process_priv'         
                              `File_priv'            
                              `Show_db_priv'         
                              `Super_priv'           
                              `Repl_slave_priv'      
                              `Repl_client_priv'     
                              `Create_user_priv'     
*Security columns*            `ssl_type'             
                              `ssl_cipher'           
                              `x509_issuer'          
                              `x509_subject'         
*Resource control columns*    `max_questions'        
                              `max_updates'          
                              `max_connections'      
                              `max_user_connections' 

The `Event_priv' and `Trigger_priv' columns were added in MySQL 5.1.6.

During the second stage of access control, the server performs request
verification to make sure that each client has sufficient privileges
for each request that it issues. In addition to the `user', `db', and
`host' grant tables, the server may also consult the `tables_priv' and
`columns_priv' tables for requests that involve tables. The
`tables_priv' and `columns_priv' tables provide finer privilege control
at the table and column levels. They have the following columns:

*Table Name*   *tables_priv*  *columns_priv*
*Scope         `Host'         `Host'
columns*                      
               `Db'           `Db'
               `User'         `User'
               `Table_name'   `Table_name'
                              `Column_name'
*Privilege     `Table_priv'   `Column_priv'
columns*                      
               `Column_priv'  
*Other         `Timestamp'    `Timestamp'
columns*                      
               `Grantor'      

The `Timestamp' and `Grantor' columns currently are unused and are
discussed no further here.

For verification of requests that involve stored routines, the server
may consult the `procs_priv' table. This table has the following
columns:

*Table Name*   *procs_priv*
*Scope         `Host'
columns*       
               `Db'
               `User'
               `Routine_name'
               `Routine_type'
*Privilege     `Proc_priv'
columns*       
*Other         `Timestamp'
columns*       
               `Grantor'

The `Routine_type' column is an `ENUM' column with values of
`'FUNCTION'' or `'PROCEDURE'' to indicate the type of routine the row
refers to. This column allows privileges to be granted separately for a
function and a procedure with the same name.

The `Timestamp' and `Grantor' columns currently are unused and are
discussed no further here.

Each grant table contains scope columns and privilege columns:

   * Scope columns determine the scope of each row (entry) in the
     tables; that is, the context in which the row applies. For
     example, a `user' table row with `Host' and `User' values of
     `'thomas.loc.gov'' and `'bob'' would be used for authenticating
     connections made to the server from the host `thomas.loc.gov' by a
     client that specifies a username of `bob'. Similarly, a `db' table
     row with `Host', `User', and `Db' column values of
     `'thomas.loc.gov'', `'bob'' and `'reports'' would be used when
     `bob' connects from the host `thomas.loc.gov' to access the
     `reports' database. The `tables_priv' and `columns_priv' tables
     contain scope columns indicating tables or table/column
     combinations to which each row applies. The `procs_priv' scope
     columns indicate the stored routine to which each row applies.

   * Privilege columns indicate which privileges are granted by a table
     row; that is, what operations can be performed. The server
     combines the information in the various grant tables to form a
     complete description of a user's privileges.  *Note
     request-access::, describes the rules that are used to do this.

Scope columns contain strings. They are declared as shown here; the
default value for each is the empty string:

*Column Name*  *Type*
`Host'         `CHAR(60)'
`User'         `CHAR(16)'
`Password'     `CHAR(16)'
`Db'           `CHAR(64)'
`Table_name'   `CHAR(64)'
`Column_name'  `CHAR(64)'
`Routine_name' `CHAR(64)'

For access-checking purposes, comparisons of `Host' values are case
insensitive.  `User', `Password', `Db', and `Table_name' values are
case sensitive. `Column_name' and `Routine_name' values are case
insensitive.

In the `user', `db', and `host' tables, each privilege is listed in a
separate column that is declared as `ENUM('N','Y') DEFAULT 'N''. In
other words, each privilege can be disabled or enabled, with the
default being disabled.

In the `tables_priv', `columns_priv', and `procs_priv' tables, the
privilege columns are declared as `SET' columns. Values in these
columns can contain any combination of the privileges controlled by the
table:

*Table Name*   *Column     *Possible Set Elements*
               Name*       
`tables_priv'  `Table_priv'`'Select', 'Insert', 'Update',
                           'Delete', 'Create', 'Drop', 'Grant',
                           'References', 'Index', 'Alter', 'Create
                           View', 'Show view', 'Trigger''
`tables_priv'  `Column_priv'`'Select', 'Insert', 'Update',
                           'References''
`columns_priv' `Column_priv'`'Select', 'Insert', 'Update',
                           'References''
`procs_priv'   `Proc_priv' `'Execute', 'Alter Routine', 'Grant''

Briefly, the server uses the grant tables in the following manner:

   * The `user' table scope columns determine whether to reject or
     allow incoming connections. For allowed connections, any
     privileges granted in the `user' table indicate the user's global
     (superuser) privileges. Any privilege granted in this table
     applies to _all_ databases on the server.

     *Note*:

     Because any global privilege is considered a privilege for all
     databases, any global privilege enables a user to see all database
     names with `SHOW DATABASES' or by examining the `SCHEMATA' table of
     `INFORMATION_SCHEMA'.

   * The `db' table scope columns determine which users can access
     which databases from which hosts. The privilege columns determine
     which operations are allowed. A privilege granted at the database
     level applies to the database and to all its tables.

   * The `host' table is used in conjunction with the `db' table when
     you want a given `db' table row to apply to several hosts.  For
     example, if you want a user to be able to use a database from
     several hosts in your network, leave the `Host' value empty in the
     user's `db' table row, then populate the `host' table with a row
     for each of those hosts. This mechanism is described more detail in
     *Note request-access::.

     *Note*:

     The `host' table must be modified directly with statements such as
     `INSERT', `UPDATE', and `DELETE'. It is not affected by statements
     such as `GRANT' and `REVOKE' that modify the grant tables
     indirectly. Most MySQL installations need not use this table at
     all.

   * The `tables_priv' and `columns_priv' tables are similar to the
     `db' table, but are more fine-grained: They apply at the table and
     column levels rather than at the database level. A privilege
     granted at the table level applies to the table and to all its
     columns. A privilege granted at the column level applies only to a
     specific column.

   * The `procs_priv' table applies to stored routines. A privilege
     granted at the routine level applies only to a single routine.

Administrative privileges (such as `RELOAD' or `SHUTDOWN') are
specified only in the `user' table. The reason for this is that
administrative operations are operations on the server itself and are
not database-specific, so there is no reason to list these privileges
in the other grant tables. In fact, to determine whether you can
perform an administrative operation, the server need consult only the
`user' table.

The `FILE' privilege also is specified only in the `user' table. It is
not an administrative privilege as such, but your ability to read or
write files on the server host is independent of the database you are
accessing.

The `mysqld' server reads the contents of the grant tables into memory
when it starts. You can tell it to re-read the tables by issuing a
`FLUSH PRIVILEGES' statement or executing a `mysqladmin
flush-privileges' or `mysqladmin reload' command. Changes to the grant
tables take effect as indicated in *Note privilege-changes::.

When you modify the contents of the grant tables, it is a good idea to
make sure that your changes set up privileges the way you want. To
check the privileges for a given account, use the `SHOW GRANTS'
statement. (See *Note show-grants::.) For example, to determine the
privileges that are granted to an account with `Host' and `User' values
of `pc84.example.com' and `bob', issue this statement:

     SHOW GRANTS FOR 'bob'@'pc84.example.com';

For additional help in diagnosing privilege-related problems, see *Note
access-denied::. For general advice on security issues, see *Note
security::.


File: manual.info,  Node: privileges-provided,  Next: connection-access,  Prev: privileges,  Up: privilege-system

5.4.3 Privileges Provided by MySQL
----------------------------------

Information about account privileges is stored in the `user', `db',
`host', `tables_priv', `columns_priv', and `procs_priv' tables in the
`mysql' database. The MySQL server reads the contents of these tables
into memory when it starts and re-reads them under the circumstances
indicated in *Note privilege-changes::. Access-control decisions are
based on the in-memory copies of the grant tables.

The names used in the `GRANT' and `REVOKE' statements to refer to
privileges are shown in the following table, along with the column name
associated with each privilege in the grant tables and the context in
which the privilege applies. Further information about the meaning of
each privilege may be found at *Note grant::.

*Privilege*            *Column*                 *Context*
`CREATE'               `Create_priv'            databases, tables, or
                                                indexes
`DROP'                 `Drop_priv'              databases or tables
`GRANT OPTION'         `Grant_priv'             databases, tables, or
                                                stored routines
`REFERENCES'           `References_priv'        databases or tables
                                                (unused)
`EVENT'                `Event_priv'             databases
`ALTER'                `Alter_priv'             tables
`DELETE'               `Delete_priv'            tables
`INDEX'                `Index_priv'             tables
`INSERT'               `Insert_priv'            tables
`SELECT'               `Select_priv'            tables
`UPDATE'               `Update_priv'            tables
`TRIGGER'              `Trigger_priv'           tables
`CREATE VIEW'          `Create_view_priv'       views
`SHOW VIEW'            `Show_view_priv'         views
`ALTER ROUTINE'        `Alter_routine_priv'     stored routines
`CREATE ROUTINE'       `Create_routine_priv'    stored routines
`EXECUTE'              `Execute_priv'           stored routines
`FILE'                 `File_priv'              file access on server host
`CREATE TEMPORARY      `Create_tmp_table_priv'  server administration
TABLES'                                         
`LOCK TABLES'          `Lock_tables_priv'       server administration
`CREATE USER'          `Create_user_priv'       server administration
`PROCESS'              `Process_priv'           server administration
`RELOAD'               `Reload_priv'            server administration
`REPLICATION CLIENT'   `Repl_client_priv'       server administration
`REPLICATION SLAVE'    `Repl_slave_priv'        server administration
`SHOW DATABASES'       `Show_db_priv'           server administration
`SHUTDOWN'             `Shutdown_priv'          server administration
`SUPER'                `Super_priv'             server administration

Some releases of MySQL introduce changes to the structure of the grant
tables to add new privileges or features. Whenever you update to a new
version of MySQL, you should update your grant tables to make sure that
they have the current structure so that you can take advantage of any
new capabilities. See *Note mysql-upgrade::.

The `EVENT' and `TRIGGER' privileges were added in MySQL 5.1.6.

To create or alter stored functions if binary logging is enabled, you
may also need the `SUPER' privilege, as described in *Note
stored-procedure-logging::.

The `CREATE' and `DROP' privileges allow you to create new databases
and tables, or to drop (remove) existing databases and tables.
Beginning with MySQL 5.1.10, the `DROP' privilege is also required in
order to use the statement `ALTER TABLE ...  DROP PARTITION' on a
partitioned table. Beginning with MySQL 5.1.16, the `DROP' privilege is
required for `TRUNCATE TABLE' (before that, `TRUNCATE TABLE' requires
the `DELETE' privilege). _If you grant the `DROP' privilege for the
`mysql' database to a user, that user can drop the database in which
the MySQL access privileges are stored._

The `SELECT', `INSERT', `UPDATE', and `DELETE' privileges allow you to
perform operations on rows in existing tables in a database. `INSERT'
is also required for the `ANALYZE TABLE', `OPTIMIZE TABLE', and `REPAIR
TABLE' table-maintenance statements.

`SELECT' statements require the `SELECT' privilege only if they actually
retrieve rows from a table. Some `SELECT' statements do not access
tables and can be executed without permission for any database. For
example, you can use the `mysql' client as a simple calculator to
evaluate expressions that make no reference to tables:

     SELECT 1+1;
     SELECT PI()*2;

The `INDEX' privilege enables you to create or drop (remove) indexes.
`INDEX' applies to existing tables. If you have the `CREATE' privilege
for a table, you can include index definitions in the `CREATE TABLE'
statement.

The `ALTER' privilege enables you to use `ALTER TABLE' to change the
structure of or rename tables.

The `CREATE ROUTINE' privilege is needed for creating stored routines
(functions and procedures).  `ALTER ROUTINE' privilege is needed for
altering or dropping stored routines, and `EXECUTE' is needed for
executing stored routines.

The `TRIGGER' privilege enables you to create and drop triggers. You
must have this privilege for a table to create or drop triggers for
that table. (Prior to MySQL 5.1.6, these operations required the `SUPER'
privilege.)

The `EVENT' privilege enables you to set up events for the event
scheduler.

The `GRANT' privilege enables you to give to other users those
privileges that you yourself possess. It can be used for databases,
tables, and stored routines.

The `FILE' privilege gives you permission to read and write files on
the server host using the `LOAD DATA INFILE' and `SELECT ... INTO
OUTFILE' statements. A user who has the `FILE' privilege can read any
file on the server host that is either world-readable or readable by the
MySQL server. (This implies the user can read any file in any database
directory, because the server can access any of those files.) The
`FILE' privilege also enables the user to create new files in any
directory where the MySQL server has write access. As a security
measure, the server will not overwrite existing files.

The `REFERENCES' privilege currently is unused.

The remaining privileges are used for administrative operations.  Many
of them can be performed by using the `mysqladmin' program or by
issuing SQL statements. The following table shows which `mysqladmin'
commands each administrative privilege enables you to execute:

*Privilege* *Commands Permitted to Privilege Holders*
`RELOAD'    `flush-hosts', `flush-logs', `flush-privileges',
            `flush-status', `flush-tables', `flush-threads',
            `refresh', `reload'
`SHUTDOWN'  `shutdown'
`PROCESS'   `processlist'
`SUPER'     `kill'

The `reload' command tells the server to re-read the grant tables into
memory.  `flush-privileges' is a synonym for `reload'. The `refresh'
command closes and reopens the log files and flushes all tables.  The
other `flush-XXX' commands perform functions similar to `refresh', but
are more specific and may be preferable in some instances. For example,
if you want to flush just the log files, `flush-logs' is a better
choice than `refresh'.

The `shutdown' command shuts down the server.  There is no
corresponding SQL statement.

The `processlist' command displays information about the threads
executing within the server (that is, information about the statements
being executed by clients). The `kill' command terminates server
threads. You can always display or kill your own threads, but you need
the `PROCESS' privilege to display threads initiated by other users and
the `SUPER' privilege to kill them. See *Note kill::.

The `CREATE TEMPORARY TABLES' privilege enables the use of the keyword
`TEMPORARY' in `CREATE TABLE' statements.

The `LOCK TABLES' privilege enables the use of explicit `LOCK TABLES'
statements to lock tables for which you have the `SELECT' privilege.
This includes the use of write locks, which prevents anyone else from
reading the locked table.

The `REPLICATION CLIENT' privilege enables the use of `SHOW MASTER
STATUS' and `SHOW SLAVE STATUS'.

The `REPLICATION SLAVE' privilege should be granted to accounts that
are used by slave servers to connect to the current server as their
master. Without this privilege, the slave cannot request updates that
have been made to databases on the master server.

The `SHOW DATABASES' privilege allows the account to see database names
by issuing the `SHOW DATABASE' statement. Accounts that do not have this
privilege see only databases for which they have some privileges, and
cannot use the statement at all if the server was started with the
`--skip-show-database' option. Note that _any_ global privilege is a
privilege for the database.

It is a good idea to grant to an account only those privileges that it
needs. You should exercise particular caution in granting the `FILE'
and administrative privileges:

   * The `FILE' privilege can be abused to read into a database table
     any files that the MySQL server can read on the server host. This
     includes all world-readable files and files in the server's data
     directory. The table can then be accessed using `SELECT' to
     transfer its contents to the client host.

   * The `GRANT' privilege enables users to give their privileges to
     other users. Two users that have different privileges and with the
     `GRANT' privilege are able to combine privileges.

   * The `ALTER' privilege may be used to subvert the privilege system
     by renaming tables.

   * The `SHUTDOWN' privilege can be abused to deny service to other
     users entirely by terminating the server.

   * The `PROCESS' privilege can be used to view the plain text of
     currently executing statements, including statements that set or
     change passwords.

   * The `SUPER' privilege can be used to terminate other clients or
     change how the server operates.

   * Privileges granted for the `mysql' database itself can be used to
     change passwords and other access privilege information. Passwords
     are stored encrypted, so a malicious user cannot simply read them
     to know the plain text password. However, a user with write access
     to the `user' table `Password' column can change an account's
     password, and then connect to the MySQL server using that account.

     MySQL Enterprise

     Accounts with unnecessary global privileges constitute a security
     risk. Subscribers to the MySQL Enterprise Monitor are
     automatically alerted to the existence of such accounts. For
     detailed information see
     `http://www.mysql.com/products/enterprise/advisors.html'.

There are some things that you cannot do with the MySQL privilege
system:

   * You cannot explicitly specify that a given user should be denied
     access. That is, you cannot explicitly match a user and then
     refuse the connection.

   * You cannot specify that a user has privileges to create or drop
     tables in a database but not to create or drop the database itself.

   * A password applies globally to an account. You cannot associate a
     password with a specific object such as a database, table, or
     routine.


File: manual.info,  Node: connection-access,  Next: request-access,  Prev: privileges-provided,  Up: privilege-system

5.4.4 Access Control, Stage 1: Connection Verification
------------------------------------------------------

When you attempt to connect to a MySQL server, the server accepts or
rejects the connection based on your identity and whether you can
verify your identity by supplying the correct password. If not, the
server denies access to you completely.  Otherwise, the server accepts
the connection, and then enters Stage 2 and waits for requests.

Your identity is based on two pieces of information:

   * The client host from which you connect

   * Your MySQL username

Identity checking is performed using the three `user' table scope
columns (`Host', `User', and `Password'). The server accepts the
connection only if the `Host' and `User' columns in some `user' table
row match the client hostname and username and the client supplies the
password specified in that row.

`Host' values in the `user' table may be specified as follows:

   * A `Host' value may be a hostname or an IP number, or `'localhost''
     to indicate the local host.

   * You can use the wildcard characters ``%'' and ``_'' in `Host'
     column values. These have the same meaning as for pattern-matching
     operations performed with the `LIKE' operator. For example, a
     `Host' value of `'%'' matches any hostname, whereas a value of
     `'%.mysql.com'' matches any host in the `mysql.com' domain.

     MySQL Enterprise

     An overly broad host specifier such as ``%'' constitutes a security
     risk. The MySQL Enterprise Monitor provides safeguards against
     this kind of vulnerability. For more information, see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   * For `Host' values specified as IP numbers, you can specify a
     netmask indicating how many address bits to use for the network
     number. For example:

          GRANT ALL PRIVILEGES ON db.* TO david@'192.58.197.0/255.255.255.0';

     This allows `david' to connect from any client host having an IP
     number `client_ip' for which the following condition is true:

          client_ip & netmask = host_ip

     That is, for the `GRANT' statement just shown:

          client_ip & 255.255.255.0 = 192.58.197.0

     IP numbers that satisfy this condition and can connect to the
     MySQL server are those in the range from `192.58.197.0' to
     `192.58.197.255'.

     Note: The netmask can only be used to tell the server to use 8,
     16, 24, or 32 bits of the address. Examples:

        * `192.0.0.0/255.0.0.0': anything on the 192 class A network

        * `192.168.0.0/255.255.0.0': anything on the 192.168 class B
          network

        * `192.168.1.0/255.255.255.0': anything on the 192.168.1 class
          C network

        * `192.168.1.1': only this specific IP

     The following netmask (28 bits) will not work:

          192.168.0.1/255.255.255.240

   * A blank `Host' value in a `db' table row means that its privileges
     should be combined with those in the row in the `host' table that
     matches the client hostname. The privileges are combined using an
     AND (intersection) operation, not OR (union).  *Note
     request-access::, discusses use of the `host' table further.

     A blank `Host' value in the other grant tables is the same as
     `'%''.

Because you can use IP wildcard values in the `Host' column (for
example, `'144.155.166.%'' to match every host on a subnet), someone
could try to exploit this capability by naming a host
`144.155.166.somewhere.com'. To foil such attempts, MySQL disallows
matching on hostnames that start with digits and a dot. Thus, if you
have a host named something like `1.2.foo.com', its name never matches
the `Host' column of the grant tables. An IP wildcard value can match
only IP numbers, not hostnames.

In the `User' column, wildcard characters are not allowed, but you can
specify a blank value, which matches any name. If the `user' table row
that matches an incoming connection has a blank username, the user is
considered to be an anonymous user with no name, not a user with the
name that the client actually specified. This means that a blank
username is used for all further access checking for the duration of
the connection (that is, during Stage 2).

The `Password' column can be blank. This is not a wildcard and does not
mean that any password matches. It means that the user must connect
without specifying a password.

Non-blank `Password' values in the `user' table represent encrypted
passwords.  MySQL does not store passwords in plaintext form for anyone
to see. Rather, the password supplied by a user who is attempting to
connect is encrypted (using the `PASSWORD()' function). The encrypted
password then is used during the connection process when checking
whether the password is correct. (This is done without the encrypted
password ever traveling over the connection.) From MySQL's point of
view, the encrypted password is the _real_ password, so you should never
give anyone access to it. In particular, _do not give
non-administrative users read access to tables in the `mysql' database_.

MySQL 5.1 employs the stronger authentication method (first implemented
in MySQL 4.1) that has better password protection during the connection
process than in earlier versions. It is secure even if TCP/IP packets
are sniffed or the `mysql' database is captured.  *Note
password-hashing::, discusses password encryption further.

The following table shows how various combinations of `Host' and `User'
values in the `user' table apply to incoming connections.

`Host' *Value*            `User'      *Allowable Connections*
                          *Value*     
`'thomas.loc.gov''        `'fred''    `fred', connecting from
                                      `thomas.loc.gov'
`'thomas.loc.gov''        `'''        Any user, connecting from
                                      `thomas.loc.gov'
`'%''                     `'fred''    `fred', connecting from any host
`'%''                     `'''        Any user, connecting from any host
`'%.loc.gov''             `'fred''    `fred', connecting from any host in
                                      the `loc.gov' domain
`'x.y.%''                 `'fred''    `fred', connecting from `x.y.net',
                                      `x.y.com', `x.y.edu', and so on
                                      (this is probably not useful)
`'144.155.166.177''       `'fred''    `fred', connecting from the host
                                      with IP address `144.155.166.177'
`'144.155.166.%''         `'fred''    `fred', connecting from any host in
                                      the `144.155.166' class C subnet
`'144.155.166.0/255.255.255.0''`'fred''    Same as previous example

It is possible for the client hostname and username of an incoming
connection to match more than one row in the `user' table. The
preceding set of examples demonstrates this: Several of the entries
shown match a connection from `thomas.loc.gov' by `fred'.

When multiple matches are possible, the server must determine which of
them to use. It resolves this issue as follows:

   * Whenever the server reads the `user' table into memory, it sorts
     the rows.

   * When a client attempts to connect, the server looks through the
     rows in sorted order.

   * The server uses the first row that matches the client hostname and
     username.

To see how this works, suppose that the `user' table looks like this:

     +-----------+----------+-
     | Host      | User     | ...
     +-----------+----------+-
     | %         | root     | ...
     | %         | jeffrey  | ...
     | localhost | root     | ...
     | localhost |          | ...
     +-----------+----------+-

When the server reads the table into memory, it orders the rows with
the most-specific `Host' values first.  Literal hostnames and IP
numbers are the most specific. (The specificity if a literal IP number
is not affected by whether it has a netmask, so `192.168.1.13' and
`192.168.1.0/255.255.255.0' are considered equally specific.) The
pattern `'%'' means `any host' and is least specific. Rows with the
same `Host' value are ordered with the most-specific `User' values
first (a blank `User' value means `any user' and is least specific).
For the `user' table just shown, the result after sorting looks like
this:

     +-----------+----------+-
     | Host      | User     | ...
     +-----------+----------+-
     | localhost | root     | ...
     | localhost |          | ...
     | %         | jeffrey  | ...
     | %         | root     | ...
     +-----------+----------+-

When a client attempts to connect, the server looks through the sorted
rows and uses the first match found. For a connection from `localhost'
by `jeffrey', two of the rows from the table match: the one with `Host'
and `User' values of `'localhost'' and `''', and the one with values of
`'%'' and `'jeffrey''. The `'localhost'' row appears first in sorted
order, so that is the one the server uses.

Here is another example. Suppose that the `user' table looks like this:

     +----------------+----------+-
     | Host           | User     | ...
     +----------------+----------+-
     | %              | jeffrey  | ...
     | thomas.loc.gov |          | ...
     +----------------+----------+-

The sorted table looks like this:

     +----------------+----------+-
     | Host           | User     | ...
     +----------------+----------+-
     | thomas.loc.gov |          | ...
     | %              | jeffrey  | ...
     +----------------+----------+-

A connection by `jeffrey' from `thomas.loc.gov' is matched by the first
row, whereas a connection by `jeffrey' from `whitehouse.gov' is matched
by the second.

It is a common misconception to think that, for a given username, all
rows that explicitly name that user are used first when the server
attempts to find a match for the connection.  This is simply not true.
The previous example illustrates this, where a connection from
`thomas.loc.gov' by `jeffrey' is first matched not by the row
containing `'jeffrey'' as the `User' column value, but by the row with
no username. As a result, `jeffrey' is authenticated as an anonymous
user, even though he specified a username when connecting.

If you are able to connect to the server, but your privileges are not
what you expect, you probably are being authenticated as some other
account. To find out what account the server used to authenticate you,
use the `CURRENT_USER()' function. (See *Note information-functions::.)
It returns a value in `USER_NAME@HOST_NAME' format that indicates the
`User' and `Host' values from the matching `user' table row. Suppose
that `jeffrey' connects and issues the following query:

     mysql> SELECT CURRENT_USER();
     +----------------+
     | CURRENT_USER() |
     +----------------+
     | @localhost     |
     +----------------+

The result shown here indicates that the matching `user' table row had
a blank `User' column value. In other words, the server is treating
`jeffrey' as an anonymous user.

Another thing you can do to diagnose authentication problems is to
print out the `user' table and sort it by hand to see where the first
match is being made.


File: manual.info,  Node: request-access,  Next: privilege-changes,  Prev: connection-access,  Up: privilege-system

5.4.5 Access Control, Stage 2: Request Verification
---------------------------------------------------

After you establish a connection, the server enters Stage 2 of access
control. For each request that you issue via that connection, the
server determines what operation you want to perform, then checks
whether you have sufficient privileges to do so. This is where the
privilege columns in the grant tables come into play. These privileges
can come from any of the `user', `db', `host', `tables_priv',
`columns_priv', or `procs_priv' tables. (You may find it helpful to
refer to *Note privileges::, which lists the columns present in each of
the grant tables.)

The `user' table grants privileges that are assigned to you on a global
basis and that apply no matter what the default database is. For
example, if the `user' table grants you the `DELETE' privilege, you can
delete rows from any table in any database on the server host! In other
words, `user' table privileges are superuser privileges. It is wise to
grant privileges in the `user' table only to superusers such as
database administrators. For other users, you should leave all
privileges in the `user' table set to `'N'' and grant privileges at
more specific levels only. You can grant privileges for particular
databases, tables, columns, or routines.

The `db' and `host' tables grant database-specific privileges. Values
in the scope columns of these tables can take the following forms:

   * The wildcard characters ``%'' and ``_'' can be used in the `Host'
     and `Db' columns of either table. These have the same meaning as
     for pattern-matching operations performed with the `LIKE'
     operator. If you want to use either character literally when
     granting privileges, you must escape it with a backslash. For
     example, to include the underscore character (``_'') as part of a
     database name, specify it as ``\_'' in the `GRANT' statement.

   * A `'%'' `Host' value in the `db' table means `any host.' A blank
     `Host' value in the `db' table means `consult the `host' table for
     further information' (a process that is described later in this
     section).

   * A `'%'' or blank `Host' value in the `host' table means `any host.'

   * A `'%'' or blank `Db' value in either table means `any database.'

   * A blank `User' value in the `db' table matches the anonymous user.

The server reads the `db' and `host' tables into memory and sorts them
at the same time that it reads the `user' table. The server sorts the
`db' table based on the `Host', `Db', and `User' scope columns, and
sorts the `host' table based on the `Host' and `Db' scope columns.  As
with the `user' table, sorting puts the most-specific values first and
least-specific values last, and when the server looks for matching
entries, it uses the first match that it finds.

The `tables_priv' `columns_priv', and `procs_priv' tables grant
table-specific, column-specific, and routine-specific privileges.
Values in the scope columns of these tables can take the following
forms:

   * The wildcard characters ``%'' and ``_'' can be used in the `Host'
     column. These have the same meaning as for pattern-matching
     operations performed with the `LIKE' operator.

   * A `'%'' or blank `Host' value means `any host.'

   * The `Db', `Table_name', and `Column_name' columns cannot contain
     wildcards or be blank.

The server sorts the `tables_priv', `columns_priv', and `procs_priv'
tables based on the `Host', `Db', and `User' columns. This is similar to
`db' table sorting, but simpler because only the `Host' column can
contain wildcards.

The server uses the sorted tables to verify each request that it
receives. For requests that require administrative privileges such as
`SHUTDOWN' or `RELOAD', the server checks only the `user' table row
because that is the only table that specifies administrative
privileges. The server grants access if the row allows the requested
operation and denies access otherwise. For example, if you want to
execute `mysqladmin shutdown' but your `user' table row doesn't grant
the `SHUTDOWN' privilege to you, the server denies access without even
checking the `db' or `host' tables. (They contain no `Shutdown_priv'
column, so there is no need to do so.)

For database-related requests (`INSERT', `UPDATE', and so on), the
server first checks the user's global (superuser) privileges by looking
in the `user' table row. If the row allows the requested operation,
access is granted. If the global privileges in the `user' table are
insufficient, the server determines the user's database-specific
privileges by checking the `db' and `host' tables:

  1. The server looks in the `db' table for a match on the `Host', `Db',
     and `User' columns. The `Host' and `User' columns are matched to
     the connecting user's hostname and MySQL username. The `Db' column
     is matched to the database that the user wants to access. If there
     is no row for the `Host' and `User', access is denied.

  2. If there is a matching `db' table row and its `Host' column is not
     blank, that row defines the user's database-specific privileges.

  3. If the matching `db' table row's `Host' column is blank, it
     signifies that the `host' table enumerates which hosts should be
     allowed access to the database. In this case, a further lookup is
     done in the `host' table to find a match on the `Host' and `Db'
     columns. If no `host' table row matches, access is denied. If
     there is a match, the user's database-specific privileges are
     computed as the intersection (_not_ the union!) of the privileges
     in the `db' and `host' table entries; that is, the privileges that
     are `'Y'' in both entries.  (This way you can grant general
     privileges in the `db' table row and then selectively restrict
     them on a host-by-host basis using the `host' table entries.)

After determining the database-specific privileges granted by the `db'
and `host' table entries, the server adds them to the global privileges
granted by the `user' table. If the result allows the requested
operation, access is granted. Otherwise, the server successively checks
the user's table and column privileges in the `tables_priv' and
`columns_priv' tables, adds those to the user's privileges, and allows
or denies access based on the result. For stored routine operations,
the server uses the `procs_priv' table rather than `tables_priv' and
`columns_priv'.

Expressed in boolean terms, the preceding description of how a user's
privileges are calculated may be summarized like this:

     global privileges
     OR (database privileges AND host privileges)
     OR table privileges
     OR column privileges
     OR routine privileges

It may not be apparent why, if the global `user' row privileges are
initially found to be insufficient for the requested operation, the
server adds those privileges to the database, table, and column
privileges later.  The reason is that a request might require more than
one type of privilege. For example, if you execute an `INSERT INTO ...
SELECT' statement, you need both the `INSERT' and the `SELECT'
privileges. Your privileges might be such that the `user' table row
grants one privilege and the `db' table row grants the other. In this
case, you have the necessary privileges to perform the request, but the
server cannot tell that from either table by itself; the privileges
granted by the entries in both tables must be combined.

The `host' table is not affected by the `GRANT' or `REVOKE' statements,
so it is unused in most MySQL installations. If you modify it directly,
you can use it for some specialized purposes, such as to maintain a
list of secure servers. For example, at TcX, the `host' table contains a
list of all machines on the local network. These are granted all
privileges.

You can also use the `host' table to indicate hosts that are _not_
secure. Suppose that you have a machine `public.your.domain' that is
located in a public area that you do not consider secure. You can allow
access to all hosts on your network except that machine by using `host'
table entries like this:

     +--------------------+----+-
     | Host               | Db | ...
     +--------------------+----+-
     | public.your.domain | %  | ... (all privileges set to 'N')
     | %.your.domain      | %  | ... (all privileges set to 'Y')
     +--------------------+----+-

Naturally, you should always test your changes to the grant tables (for
example, by using `SHOW GRANTS') to make sure that your access
privileges are actually set up the way you think they are.


File: manual.info,  Node: privilege-changes,  Next: access-denied,  Prev: request-access,  Up: privilege-system

5.4.6 When Privilege Changes Take Effect
----------------------------------------

When `mysqld' starts, it reads all grant table contents into memory.
The in-memory tables become effective for access control at that point.

When the server reloads the grant tables, privileges for existing
client connections are affected as follows:

   * Table and column privilege changes take effect with the client's
     next request.

   * Database privilege changes take effect at the next `USE DB_NAME'
     statement.

     *Note*:

     Client applications may cache the database name; thus, this effect
     may not be visible to them without actually changing to a
     different database or executing a `FLUSH PRIVILEGES' statement.

   * Changes to global privileges and passwords take effect the next
     time the client connects.

If you modify the grant tables indirectly using statements such as
`GRANT', `REVOKE', or `SET PASSWORD', the server notices these changes
and loads the grant tables into memory again immediately.

If you modify the grant tables directly using statements such as
`INSERT', `UPDATE', or `DELETE', your changes have no effect on
privilege checking until you either restart the server or tell it to
reload the tables. To reload the grant tables manually, issue a `FLUSH
PRIVILEGES' statement or execute a `mysqladmin flush-privileges' or
`mysqladmin reload' command.

If you change the grant tables directly but forget to reload them, your
changes have _no effect_ until you restart the server. This may leave
you wondering why your changes do not seem to make any difference!


File: manual.info,  Node: access-denied,  Next: password-hashing,  Prev: privilege-changes,  Up: privilege-system

5.4.7 Causes of `Access denied' Errors
--------------------------------------

If you encounter problems when you try to connect to the MySQL server,
the following items describe some courses of action you can take to
correct the problem.

   * Make sure that the server is running. If it is not running, you
     cannot connect to it. For example, if you attempt to connect to
     the server and see a message such as one of those following, one
     cause might be that the server is not running:

          shell> mysql
          ERROR 2003: Can't connect to MySQL server on 'HOST_NAME' (111)
          shell> mysql
          ERROR 2002: Can't connect to local MySQL server through socket
          '/tmp/mysql.sock' (111)

     It might also be that the server is running, but you are trying to
     connect using a TCP/IP port, named pipe, or Unix socket file
     different from the one on which the server is listening. To
     correct this when you invoke a client program, specify a `--port'
     option to indicate the proper port number, or a `--socket' option
     to indicate the proper named pipe or Unix socket file. To find out
     where the socket file is, you can use this command:

          shell> netstat -ln | grep mysql

   * The grant tables must be properly set up so that the server can
     use them for access control. For some distribution types (such as
     binary distributions on Windows, or RPM distributions on Linux),
     the installation process initializes the `mysql' database
     containing the grant tables. For distributions that do not do
     this, you must initialize the grant tables manually by running the
     `mysql_install_db' script. For details, see *Note
     unix-post-installation::.

     One way to determine whether you need to initialize the grant
     tables is to look for a `mysql' directory under the data
     directory. (The data directory normally is named `data' or `var'
     and is located under your MySQL installation directory.) Make sure
     that you have a file named `user.MYD' in the `mysql' database
     directory. If you do not, execute the `mysql_install_db' script.
     After running this script and starting the server, test the
     initial privileges by executing this command:

          shell> mysql -u root test

     The server should let you connect without error.

   * After a fresh installation, you should connect to the server and
     set up your users and their access permissions:

          shell> mysql -u root mysql

     The server should let you connect because the MySQL `root' user
     has no password initially. That is also a security risk, so
     setting the password for the `root' accounts is something you
     should do while you're setting up your other MySQL accounts. For
     instructions on setting the initial passwords, see *Note
     default-privileges::.

     MySQL Enterprise

     The MySQL Enterprise Monitor enforces security-related best
     practices. For example, subscribers are alerted whenever there is
     any account without a password. For more information see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   * If you have updated an existing MySQL installation to a newer
     version, did you run the `mysql_upgrade' script? If not, do so. The
     structure of the grant tables changes occasionally when new
     capabilities are added, so after an upgrade you should always make
     sure that your tables have the current structure. For
     instructions, see *Note mysql-upgrade::.

   * If a client program receives the following error message when it
     tries to connect, it means that the server expects passwords in a
     newer format than the client is capable of generating:

          shell> mysql
          Client does not support authentication protocol requested
          by server; consider upgrading MySQL client

     For information on how to deal with this, see *Note
     password-hashing::, and *Note old-client::.

   * If you try to connect as `root' and get the following error, it
     means that you do not have a row in the `user' table with a `User'
     column value of `'root'' and that `mysqld' cannot resolve the
     hostname for your client:

          Access denied for user ''@'unknown' to database mysql

     In this case, you must restart the server with the
     `--skip-grant-tables' option and edit your `/etc/hosts' file or
     `\windows\hosts' file to add an entry for your host.

   * Remember that client programs use connection parameters specified
     in option files or environment variables. If a client program
     seems to be sending incorrect default connection parameters when
     you have not specified them on the command line, check your
     environment and any applicable option files. For example, if you
     get `Access denied' when you run a client without any options,
     make sure that you have not specified an old password in any of
     your option files!

     You can suppress the use of option files by a client program by
     invoking it with the `--no-defaults' option. For example:

          shell> mysqladmin --no-defaults -u root version

     The option files that clients use are listed in *Note
     option-files::. Environment variables are listed in *Note
     environment-variables::.

   * If you get the following error, it means that you are using an
     incorrect `root' password:

          shell> mysqladmin -u root -pXXXX ver
          Access denied for user 'root'@'localhost' (using password: YES)

     If the preceding error occurs even when you have not specified a
     password, it means that you have an incorrect password listed in
     some option file. Try the `--no-defaults' option as described in
     the previous item.

     For information on changing passwords, see *Note passwords::.

     If you have lost or forgotten the `root' password, you can restart
     `mysqld' with `--skip-grant-tables' to change the password.  See
     *Note resetting-permissions::.

   * If you change a password by using `SET PASSWORD', `INSERT', or
     `UPDATE', you must encrypt the password using the `PASSWORD()'
     function. If you do not use `PASSWORD()' for these statements, the
     password will not work. For example, the following statement sets
     a password, but fails to encrypt it, so the user is not able to
     connect afterward:

          SET PASSWORD FOR 'abe'@'HOST_NAME' = 'eagle';

     Instead, set the password like this:

          SET PASSWORD FOR 'abe'@'HOST_NAME' = PASSWORD('eagle');

     The `PASSWORD()' function is unnecessary when you specify a
     password using the `GRANT' or `CREATE USER' statements, or the
     `mysqladmin password' command. Each of those automatically uses
     `PASSWORD()' to encrypt the password. See *Note passwords::, and
     *Note create-user::.

   * `localhost' is a synonym for your local hostname, and is also the
     default host to which clients try to connect if you specify no
     host explicitly.

     To avoid this problem on such systems, you can use a
     `--host=127.0.0.1' option to name the server host explicitly. This
     will make a TCP/IP connection to the local `mysqld' server. You
     can also use TCP/IP by specifying a `--host' option that uses the
     actual hostname of the local host. In this case, the hostname must
     be specified in a `user' table row on the server host, even though
     you are running the client program on the same host as the server.

   * If you get an `Access denied' error when trying to connect to the
     database with `mysql -u USER_NAME', you may have a problem with
     the `user' table. Check this by executing `mysql -u root mysql' and
     issuing this SQL statement:

          SELECT * FROM user;

     The result should include a row with the `Host' and `User' columns
     matching your computer's hostname and your MySQL username.

   * The `Access denied' error message tells you who you are trying to
     log in as, the client host from which you are trying to connect,
     and whether you were using a password. Normally, you should have
     one row in the `user' table that exactly matches the hostname and
     username that were given in the error message.  For example, if
     you get an error message that contains `using password: NO', it
     means that you tried to log in without a password.

   * If the following error occurs when you try to connect from a host
     other than the one on which the MySQL server is running, it means
     that there is no row in the `user' table with a `Host' value that
     matches the client host:

          Host ... is not allowed to connect to this MySQL server

     You can fix this by setting up an account for the combination of
     client hostname and username that you are using when trying to
     connect.

     If you do not know the IP number or hostname of the machine from
     which you are connecting, you should put a row with `'%'' as the
     `Host' column value in the `user' table. After trying to connect
     from the client machine, use a `SELECT USER()' query to see how
     you really did connect.  (Then change the `'%'' in the `user'
     table row to the actual hostname that shows up in the log.
     Otherwise, your system is left insecure because it allows
     connections from any host for the given username.)

     On Linux, another reason that this error might occur is that you
     are using a binary MySQL version that is compiled with a different
     version of the `glibc' library than the one you are using. In this
     case, you should either upgrade your operating system or `glibc',
     or download a source distribution of MySQL version and compile it
     yourself. A source RPM is normally trivial to compile and install,
     so this is not a big problem.

   * If you specify a hostname when trying to connect, but get an error
     message where the hostname is not shown or is an IP number, it
     means that the MySQL server got an error when trying to resolve
     the IP number of the client host to a name:

          shell> mysqladmin -u root -pXXXX -h SOME_HOSTNAME ver
          Access denied for user 'root'@'' (using password: YES)

     This indicates a DNS problem. To fix it, execute `mysqladmin
     flush-hosts' to reset the internal DNS hostname cache. See *Note
     dns::.

     Some permanent solutions are:

        * Determine what is wrong with your DNS server and fix it.

        * Specify IP numbers rather than hostnames in the MySQL grant
          tables.

        * Put an entry for the client machine name in `/etc/hosts' or
          `\windows\hosts'.

        * Start `mysqld' with the `--skip-name-resolve' option.

        * Start `mysqld' with the `--skip-host-cache' option.

        * On Unix, if you are running the server and the client on the
          same machine, connect to `localhost'. Unix connections to
          `localhost' use a Unix socket file rather than TCP/IP.

        * On Windows, if you are running the server and the client on
          the same machine and the server supports named pipe
          connections, connect to the hostname `.' (period).
          Connections to `.' use a named pipe rather than TCP/IP.

   * If `mysql -u root test' works but `mysql -h YOUR_HOSTNAME -u root
     test' results in `Access denied' (where YOUR_HOSTNAME is the actual
     hostname of the local host), you may not have the correct name for
     your host in the `user' table. A common problem here is that the
     `Host' value in the `user' table row specifies an unqualified
     hostname, but your system's name resolution routines return a
     fully qualified domain name (or vice versa). For example, if you
     have an entry with host `'tcx'' in the `user' table, but your DNS
     tells MySQL that your hostname is `'tcx.subnet.se'', the entry
     does not work.  Try adding an entry to the `user' table that
     contains the IP number of your host as the `Host' column value.
     (Alternatively, you could add an entry to the `user' table with a
     `Host' value that contains a wildcard; for example, `'tcx.%''.
     However, use of hostnames ending with ``%'' is _insecure_ and is
     _not_ recommended!)

   * If `mysql -u USER_NAME test' works but `mysql -u USER_NAME
     OTHER_DB_NAME' does not, you have not granted database access for
     OTHER_DB_NAME to the given user.

   * If `mysql -u USER_NAME' works when executed on the server host,
     but `mysql -h HOST_NAME -u USER_NAME' does not work when executed
     on a remote client host, you have not enabled access to the server
     for the given username from the remote host.

   * If you cannot figure out why you get `Access denied', remove from
     the `user' table all entries that have `Host' values containing
     wildcards (entries that contain ``%'' or ``_''). A very common
     error is to insert a new entry with `Host'=`'%'' and
     `User'=`'SOME_USER'', thinking that this allows you to specify
     `localhost' to connect from the same machine. The reason that this
     does not work is that the default privileges include an entry with
     `Host'=`'localhost'' and `User'=`'''. Because that entry has a
     `Host' value `'localhost'' that is more specific than `'%'', it is
     used in preference to the new entry when connecting from
     `localhost'! The correct procedure is to insert a second entry with
     `Host'=`'localhost'' and `User'=`'SOME_USER'', or to delete the
     entry with `Host'=`'localhost'' and `User'=`'''. After deleting
     the entry, remember to issue a `FLUSH PRIVILEGES' statement to
     reload the grant tables.

   * If you get the following error, you may have a problem with the
     `db' or `host' table:

          Access to database denied

     If the entry selected from the `db' table has an empty value in
     the `Host' column, make sure that there are one or more
     corresponding entries in the `host' table specifying which hosts
     the `db' table entry applies to.

   * If you are able to connect to the MySQL server, but get an `Access
     denied' message whenever you issue a `SELECT ... INTO OUTFILE' or
     `LOAD DATA INFILE' statement, your entry in the `user' table does
     not have the `FILE' privilege enabled.

   * If you change the grant tables directly (for example, by using
     `INSERT', `UPDATE', or `DELETE' statements) and your changes seem
     to be ignored, remember that you must execute a `FLUSH PRIVILEGES'
     statement or a `mysqladmin flush-privileges' command to cause the
     server to re-read the privilege tables. Otherwise, your changes
     have no effect until the next time the server is restarted.
     Remember that after you change the `root' password with an
     `UPDATE' command, you won't need to specify the new password until
     after you flush the privileges, because the server won't know
     you've changed the password yet!

   * If your privileges seem to have changed in the middle of a
     session, it may be that a MySQL administrator has changed them.
     Reloading the grant tables affects new client connections, but it
     also affects existing connections as indicated in *Note
     privilege-changes::.

   * If you have access problems with a Perl, PHP, Python, or ODBC
     program, try to connect to the server with `mysql -u USER_NAME
     DB_NAME' or `mysql -u USER_NAME -pYOUR_PASS DB_NAME'. If you are
     able to connect using the `mysql' client, the problem lies with
     your program, not with the access privileges. (There is no space
     between `-p' and the password; you can also use the
     `--password=YOUR_PASS' syntax to specify the password. If you use
     the `-p' `--password'option with no password value, MySQL prompts
     you for the password.)

   * For testing, start the `mysqld' server with the
     `--skip-grant-tables' option. Then you can change the MySQL grant
     tables and use the `mysqlaccess' script to check whether your
     modifications have the desired effect. When you are satisfied with
     your changes, execute `mysqladmin flush-privileges' to tell the
     `mysqld' server to start using the new grant tables. (Reloading
     the grant tables overrides the `--skip-grant-tables' option. This
     enables you to tell the server to begin using the grant tables
     again without stopping and restarting it.)

   * If everything else fails, start the `mysqld' server with a
     debugging option (for example, `--debug=d,general,query').  This
     prints host and user information about attempted connections, as
     well as information about each command issued. See MySQL
     Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

   * If you have any other problems with the MySQL grant tables and
     feel you must post the problem to the mailing list, always provide
     a dump of the MySQL grant tables. You can dump the tables with the
     `mysqldump mysql' command. To file a bug report, see the
     instructions at *Note bug-reports::. In some cases, you may need
     to restart `mysqld' with `--skip-grant-tables' to run `mysqldump'.


File: manual.info,  Node: password-hashing,  Prev: access-denied,  Up: privilege-system

5.4.8 Password Hashing as of MySQL 4.1
--------------------------------------

* Menu:

* application-password-use::     Implications of Password Hashing Changes for Application Programs

MySQL user accounts are listed in the `user' table of the `mysql'
database. Each MySQL account is assigned a password, although what is
stored in the `Password' column of the `user' table is not the
plaintext version of the password, but a hash value computed from it.
Password hash values are computed by the `PASSWORD()' function.

MySQL uses passwords in two phases of client/server communication:

   * When a client attempts to connect to the server, there is an
     initial authentication step in which the client must present a
     password that has a hash value matching the hash value stored in
     the `user' table for the account that the client wants to use.

   * After the client connects, it can (if it has sufficient
     privileges) set or change the password hashes for accounts listed
     in the `user' table. The client can do this by using the
     `PASSWORD()' function to generate a password hash, or by using the
     `GRANT' or `SET PASSWORD' statements.

In other words, the server _uses_ hash values during authentication
when a client first attempts to connect.  The server _generates_ hash
values if a connected client invokes the `PASSWORD()' function or uses a
`GRANT' or `SET PASSWORD' statement to set or change a password.

The password hashing mechanism was updated in MySQL 4.1 to provide
better security and to reduce the risk of passwords being intercepted.
However, this new mechanism is understood only by MySQL 4.1 (and newer)
servers and clients, which can result in some compatibility problems. A
4.1 or newer client can connect to a pre-4.1 server, because the client
understands both the old and new password hashing mechanisms. However,
a pre-4.1 client that attempts to connect to a 4.1 or newer server may
run into difficulties. For example, a 3.23 `mysql' client that attempts
to connect to a 5.1 server may fail with the following error message:

     shell> mysql -h localhost -u root
     Client does not support authentication protocol requested
     by server; consider upgrading MySQL client

Another common example of this phenomenon occurs for attempts to use
the older PHP `mysql' extension after upgrading to MySQL 4.1 or newer.
(See *Note php-problems::.)

The following discussion describes the differences between the old and
new password mechanisms, and what you should do if you upgrade your
server but need to maintain backward compatibility with pre-4.1
clients. Additional information can be found in *Note old-client::.
This information is of particular importance to PHP programmers
migrating MySQL databases from version 4.0 or lower to version 4.1 or
higher.

*Note*:

This discussion contrasts 4.1 behavior with pre-4.1 behavior, but the
4.1 behavior described here actually begins with 4.1.1. MySQL 4.1.0 is
an `odd' release because it has a slightly different mechanism than
that implemented in 4.1.1 and up. Differences between 4.1.0 and more
recent versions are described further in MySQL 5.0 Reference Manual.

Prior to MySQL 4.1, password hashes computed by the `PASSWORD()'
function are 16 bytes long. Such hashes look like this:

     mysql> SELECT PASSWORD('mypass');
     +--------------------+
     | PASSWORD('mypass') |
     +--------------------+
     | 6f8c114b58f2ce9e   |
     +--------------------+

The `Password' column of the `user' table (in which these hashes are
stored) also is 16 bytes long before MySQL 4.1.

As of MySQL 4.1, the `PASSWORD()' function has been modified to produce
a longer 41-byte hash value:

     mysql> SELECT PASSWORD('mypass');
     +-------------------------------------------+
     | PASSWORD('mypass')                        |
     +-------------------------------------------+
     | *6C8989366EAF75BB670AD8EA7A7FC1176A95CEF4 |
     +-------------------------------------------+

Accordingly, the `Password' column in the `user' table also must be 41
bytes long to store these values:

   * If you perform a new installation of MySQL 5.1, the `Password'
     column is made 41 bytes long automatically.

   * Upgrading from MySQL 4.1 (4.1.1 or later in the 4.1 series) to
     MySQL 5.1 should not give rise to any issues in this regard
     because both versions use the same password hashing mechanism. If
     you wish to upgrade an older release of MySQL to version 5.1, you
     should upgrade to version 4.1 first, then upgrade the 4.1
     installation to 5.1.

A widened `Password' column can store password hashes in both the old
and new formats. The format of any given password hash value can be
determined two ways:

   * The obvious difference is the length (16 bytes versus 41 bytes).

   * A second difference is that password hashes in the new format
     always begin with a ``*'' character, whereas passwords in the old
     format never do.

The longer password hash format has better cryptographic properties,
and client authentication based on long hashes is more secure than that
based on the older short hashes.

The differences between short and long password hashes are relevant
both for how the server uses passwords during authentication and for
how it generates password hashes for connected clients that perform
password-changing operations.

The way in which the server uses password hashes during authentication
is affected by the width of the `Password' column:

   * If the column is short, only short-hash authentication is used.

   * If the column is long, it can hold either short or long hashes,
     and the server can use either format:

        * Pre-4.1 clients can connect, although because they know only
          about the old hashing mechanism, they can authenticate only
          using accounts that have short hashes.

        * 4.1 and later clients can authenticate using accounts that
          have short or long hashes.

Even for short-hash accounts, the authentication process is actually a
bit more secure for 4.1 and later clients than for older clients. In
terms of security, the gradient from least to most secure is:

   * Pre-4.1 client authenticating with short password hash

   * 4.1 or later client authenticating with short password hash

   * 4.1 or later client authenticating with long password hash

The way in which the server generates password hashes for connected
clients is affected by the width of the `Password' column and by the
`--old-passwords' option. A 4.1 or later server generates long hashes
only if certain conditions are met: The `Password' column must be wide
enough to hold long values and the `--old-passwords' option must not be
given. These conditions apply as follows:

   * The `Password' column must be wide enough to hold long hashes (41
     bytes). If the column has not been updated and still has the
     pre-4.1 width of 16 bytes, the server notices that long hashes
     cannot fit into it and generates only short hashes when a client
     performs password-changing operations using `PASSWORD()', `GRANT',
     or `SET PASSWORD'. This is the behavior that occurs if you have
     upgraded to 4.1 but have not yet run the
     `mysql_fix_privilege_tables' script to widen the `Password' column.

   * If the `Password' column is wide, it can store either short or
     long password hashes. In this case, `PASSWORD()', `GRANT', and `SET
     PASSWORD' generate long hashes unless the server was started with
     the `--old-passwords' option. That option forces the server to
     generate short password hashes instead.

The purpose of the `--old-passwords' option is to enable you to
maintain backward compatibility with pre-4.1 clients under
circumstances where the server would otherwise generate long password
hashes. The option doesn't affect authentication (4.1 and later clients
can still use accounts that have long password hashes), but it does
prevent creation of a long password hash in the `user' table as the
result of a password-changing operation. Were that to occur, the
account no longer could be used by pre-4.1 clients. Without the
`--old-passwords' option, the following undesirable scenario is
possible:

   * An old client connects to an account that has a short password
     hash.

   * The client changes its own password. Without `--old-passwords',
     this results in the account having a long password hash.

   * The next time the old client attempts to connect to the account,
     it cannot, because the account has a long password hash that
     requires the new hashing mechanism during authentication. (Once an
     account has a long password hash in the user table, only 4.1 and
     later clients can authenticate for it, because pre-4.1 clients do
     not understand long hashes.)

This scenario illustrates that, if you must support older pre-4.1
clients, it is dangerous to run a 4.1 or newer server without using the
`--old-passwords' option. By running the server with `--old-passwords',
password-changing operations do not generate long password hashes and
thus do not cause accounts to become inaccessible to older clients.
(Those clients cannot inadvertently lock themselves out by changing
their password and ending up with a long password hash.)

The downside of the `--old-passwords' option is that any passwords you
create or change use short hashes, even for 4.1 clients. Thus, you lose
the additional security provided by long password hashes. If you want
to create an account that has a long hash (for example, for use by 4.1
clients), you must do so while running the server without
`--old-passwords'.

MySQL Enterprise

Subscribers to the MySQL Enterprise Monitor are automatically alerted
whenever a server is running with the `--old-passwords' option. For
more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

The following scenarios are possible for running a 4.1 or later server:

*Scenario 1:* Short `Password' column in user table:

   * Only short hashes can be stored in the `Password' column.

   * The server uses only short hashes during client authentication.

   * For connected clients, password hash-generating operations
     involving `PASSWORD()', `GRANT', or `SET PASSWORD' use short
     hashes exclusively. Any change to an account's password results in
     that account having a short password hash.

   * The `--old-passwords' option can be used but is superfluous
     because with a short `Password' column, the server generates only
     short password hashes anyway.

*Scenario 2:* Long `Password' column; server not started with
`--old-passwords' option:

   * Short or long hashes can be stored in the `Password' column.

   * 4.1 and later clients can authenticate using accounts that have
     short or long hashes.

   * Pre-4.1 clients can authenticate only using accounts that have
     short hashes.

   * For connected clients, password hash-generating operations
     involving `PASSWORD()', `GRANT', or `SET PASSWORD' use long hashes
     exclusively. A change to an account's password results in that
     account having a long password hash.

As indicated earlier, a danger in this scenario is that it is possible
for accounts that have a short password hash to become inaccessible to
pre-4.1 clients. A change to such an account's password made via
`GRANT', `PASSWORD()', or `SET PASSWORD' results in the account being
given a long password hash. From that point on, no pre-4.1 client can
authenticate to that account until the client upgrades to 4.1.

To deal with this problem, you can change a password in a special way.
For example, normally you use `SET PASSWORD' as follows to change an
account password:

     SET PASSWORD FOR 'SOME_USER'@'SOME_HOST' = PASSWORD('mypass');

To change the password but create a short hash, use the
`OLD_PASSWORD()' function instead:

     SET PASSWORD FOR 'SOME_USER'@'SOME_HOST' = OLD_PASSWORD('mypass');

`OLD_PASSWORD()' is useful for situations in which you explicitly want
to generate a short hash.

*Scenario 3:* Long `Password' column; 4.1 or newer server started with
`--old-passwords' option:

   * Short or long hashes can be stored in the `Password' column.

   * 4.1 and later clients can authenticate for accounts that have
     short or long hashes (but note that it is possible to create long
     hashes only when the server is started without `--old-passwords').

   * Pre-4.1 clients can authenticate only for accounts that have short
     hashes.

   * For connected clients, password hash-generating operations
     involving `PASSWORD()', `GRANT', or `SET PASSWORD' use short
     hashes exclusively. Any change to an account's password results in
     that account having a short password hash.

In this scenario, you cannot create accounts that have long password
hashes, because the `--old-passwords' option prevents generation of
long hashes. Also, if you create an account with a long hash before
using the `--old-passwords' option, changing the account's password
while `--old-passwords' is in effect results in the account being given
a short password, causing it to lose the security benefits of a longer
hash.

The disadvantages for these scenarios may be summarized as follows:

In scenario 1, you cannot take advantage of longer hashes that provide
more secure authentication.

In scenario 2, accounts with short hashes become inaccessible to
pre-4.1 clients if you change their passwords without explicitly using
`OLD_PASSWORD()'.

In scenario 3, `--old-passwords' prevents accounts with short hashes
from becoming inaccessible, but password-changing operations cause
accounts with long hashes to revert to short hashes, and you cannot
change them back to long hashes while `--old-passwords' is in effect.


File: manual.info,  Node: application-password-use,  Prev: password-hashing,  Up: password-hashing

5.4.8.1 Implications of Password Hashing Changes for Application Programs
.........................................................................

An upgrade to MySQL version 4.1 or later can cause compatibility issues
for applications that use `PASSWORD()' to generate passwords for their
own purposes. Applications really should not do this, because
`PASSWORD()' should be used only to manage passwords for MySQL
accounts. But some applications use `PASSWORD()' for their own purposes
anyway.

If you upgrade to 4.1 or later from a pre-4.1 version of MySQL and run
the server under conditions where it generates long password hashes, an
application using `PASSWORD()' for its own passwords breaks. The
recommended course of action in such cases is to modify the application
to use another function, such as `SHA1()' or `MD5()', to produce hashed
values. If that is not possible, you can use the `OLD_PASSWORD()'
function, which is provided for generate short hashes in the old format.
However, you should note that `OLD_PASSWORD()' may one day no longer be
supported.

If the server is running under circumstances where it generates short
hashes, `OLD_PASSWORD()' is available but is equivalent to `PASSWORD()'.

PHP programmers migrating their MySQL databases from version 4.0 or
lower to version 4.1 or higher should see *Note php::.


File: manual.info,  Node: user-account-management,  Next: multiple-servers,  Prev: privilege-system,  Up: server-administration

5.5 MySQL User Account Management
=================================

* Menu:

* user-names::                   MySQL Usernames and Passwords
* adding-users::                 Adding New User Accounts to MySQL
* removing-users::               Removing User Accounts from MySQL
* user-resources::               Limiting Account Resources
* passwords::                    Assigning Account Passwords
* password-security::            Keeping Your Password Secure
* secure-connections::           Using SSL for Secure Connections

This section describes how to set up accounts for clients of your MySQL
server. It discusses the following topics:

   * The meaning of account names and passwords as used in MySQL and
     how that compares to names and passwords used by your operating
     system

   * How to set up new accounts and remove existing accounts

   * How to change passwords

   * Guidelines for using passwords securely

   * How to use secure connections with SSL


File: manual.info,  Node: user-names,  Next: adding-users,  Prev: user-account-management,  Up: user-account-management

5.5.1 MySQL Usernames and Passwords
-----------------------------------

A MySQL account is defined in terms of a username and the client host
or hosts from which the user can connect to the server. The account
also has a password. There are several distinctions between the way
usernames and passwords are used by MySQL and the way they are used by
your operating system:

   * Usernames, as used by MySQL for authentication purposes, have
     nothing to do with usernames (login names) as used by Windows or
     Unix. On Unix, most MySQL clients by default try to log in using
     the current Unix username as the MySQL username, but that is for
     convenience only. The default can be overridden easily, because
     client programs allow any username to be specified with a `-u' or
     `--user' option. Because this means that anyone can attempt to
     connect to the server using any username, you cannot make a
     database secure in any way unless all MySQL accounts have
     passwords. Anyone who specifies a username for an account that has
     no password is able to connect successfully to the server.

   * MySQL usernames can be up to 16 characters long. This limit is
     hard-coded in the MySQL servers and clients, and trying to
     circumvent it by modifying the definitions of the tables in the
     `mysql' database _does not work_.

     *Note*:

     _You should never alter any of the tables in the `mysql' database
     in any manner whatsoever except by means of the procedure
     prescribed by MySQL AB that is described in *Note mysql-upgrade::.
     Attempting to redefine MySQL's system tables in any other fashion
     results in undefined (and unsupported!)  behavior_.

     Operating system usernames are completely unrelated to MySQL
     usernames and may even be of a different maximum length. For
     example, Unix usernames typically are limited to eight characters.

   * MySQL passwords have nothing to do with passwords for logging in
     to your operating system. There is no necessary connection between
     the password you use to log in to a Windows or Unix machine and
     the password you use to access the MySQL server on that machine.

   * MySQL encrypts passwords using its own algorithm. This encryption
     is different from that used during the Unix login process. MySQL
     password encryption is the same as that implemented by the
     `PASSWORD()' SQL function.  Unix password encryption is the same
     as that implemented by the `ENCRYPT()' SQL function.  See the
     descriptions of the `PASSWORD()' and `ENCRYPT()' functions in
     *Note encryption-functions::. From version 4.1 on, MySQL employs a
     stronger authentication method that has better password protection
     during the connection process than in earlier versions. It is
     secure even if TCP/IP packets are sniffed or the `mysql' database
     is captured. (In earlier versions, even though passwords are
     stored in encrypted form in the `user' table, knowledge of the
     encrypted password value could be used to connect to the MySQL
     server.)

When you install MySQL, the grant tables are populated with an initial
set of accounts. These accounts have names and access privileges that
are described in *Note default-privileges::, which also discusses how
to assign passwords to them. Thereafter, you normally set up, modify,
and remove MySQL accounts using statements such as `GRANT' and
`REVOKE'. See *Note account-management-sql::.

When you connect to a MySQL server with a command-line client, you
should specify the username and password for the account that you want
to use:

     shell> mysql --user=monty --password=GUESS DB_NAME

If you prefer short options, the command looks like this:

     shell> mysql -u monty -pGUESS DB_NAME

There must be _no space_ between the `-p' option and the following
password value. See *Note connecting::.

The preceding commands include the password value on the command line,
which can be a security risk. See *Note password-security::. To avoid
this problem, specify the `--password' or `-p' option without any
following password value:

     shell> mysql --user=monty --password DB_NAME
     shell> mysql -u monty -p DB_NAME

When the password option has no password value, the client program
prints a prompt and waits for you to enter the password.  (In these
examples, DB_NAME is _not_ interpreted as a password because it is
separated from the preceding password option by a space.)

On some systems, the library routine that MySQL uses to prompt for a
password automatically limits the password to eight characters. That is
a problem with the system library, not with MySQL. Internally, MySQL
doesn't have any limit for the length of the password. To work around
the problem, change your MySQL password to a value that is eight or
fewer characters long, or put your password in an option file.


File: manual.info,  Node: adding-users,  Next: removing-users,  Prev: user-names,  Up: user-account-management

5.5.2 Adding New User Accounts to MySQL
---------------------------------------

You can create MySQL accounts in two ways:

   * By using statements intended for creating accounts, such as
     `CREATE USER' or `GRANT'

   * By manipulating the MySQL grant tables directly with statements
     such as `INSERT', `UPDATE', or `DELETE'

The preferred method is to use account-creation statements because they
are more concise and less error-prone.  `CREATE USER' and `GRANT' are
described in *Note create-user::, and *Note grant::.

Another option for creating accounts is to use one of several available
third-party programs that offer capabilities for MySQL account
administration. `phpMyAdmin' is one such program.

The following examples show how to use the `mysql' client program to
set up new users.  These examples assume that privileges are set up
according to the defaults described in *Note default-privileges::.
This means that to make changes, you must connect to the MySQL server
as the MySQL `root' user, and the `root' account must have the `INSERT'
privilege for the `mysql' database and the `RELOAD' administrative
privilege.

As noted in the examples where appropriate, some of the statements will
fail if you have the server's SQL mode has been set to enable certain
restrictions. In particular, strict mode (`STRICT_TRANS_TABLES',
`STRICT_ALL_TABLES') and `NO_AUTO_CREATE_USER' will prevent the server
from accepting some of the statements. Workarounds are indicated for
these cases. For more information about SQL modes and their effect on
grant table manipulation, see *Note server-sql-mode::, and *Note
grant::.

First, use the `mysql' program to connect to the server as the MySQL
`root' user:

     shell> mysql --user=root mysql

If you have assigned a password to the `root' account, you'll also need
to supply a `--password' or `-p' option for this `mysql' command and
also for those later in this section.

After connecting to the server as `root', you can add new accounts. The
following statements use `GRANT' to set up four new accounts:

     mysql> GRANT ALL PRIVILEGES ON *.* TO 'monty'@'localhost'
         ->     IDENTIFIED BY 'some_pass' WITH GRANT OPTION;
     mysql> GRANT ALL PRIVILEGES ON *.* TO 'monty'@'%'
         ->     IDENTIFIED BY 'some_pass' WITH GRANT OPTION;
     mysql> GRANT RELOAD,PROCESS ON *.* TO 'admin'@'localhost';
     mysql> GRANT USAGE ON *.* TO 'dummy'@'localhost';

The accounts created by these `GRANT' statements have the following
properties:

   * Two of the accounts have a username of `monty' and a password of
     `some_pass'. Both accounts are superuser accounts with full
     privileges to do anything. One account (`'monty'@'localhost'') can
     be used only when connecting from the local host. The other
     (`'monty'@'%'') can be used to connect from any other host. Note
     that it is necessary to have both accounts for `monty' to be able
     to connect from anywhere as `monty'. Without the `localhost'
     account, the anonymous-user account for `localhost' that is
     created by `mysql_install_db' would take precedence when `monty'
     connects from the local host.  As a result, `monty' would be
     treated as an anonymous user. The reason for this is that the
     anonymous-user account has a more specific `Host' column value
     than the `'monty'@'%'' account and thus comes earlier in the
     `user' table sort order.  (`user' table sorting is discussed in
     *Note connection-access::.)

   * One account has a username of `admin' and no password. This
     account can be used only by connecting from the local host. It is
     granted the `RELOAD' and `PROCESS' administrative privileges.
     These privileges allow the `admin' user to execute the `mysqladmin
     reload', `mysqladmin refresh', and `mysqladmin flush-XXX'
     commands, as well as `mysqladmin processlist' . No privileges are
     granted for accessing any databases. You could add such privileges
     later by issuing additional `GRANT' statements.

   * One account has a username of `dummy' and no password. This
     account can be used only by connecting from the local host. No
     privileges are granted. The `USAGE' privilege in the `GRANT'
     statement enables you to create an account without giving it any
     privileges. It has the effect of setting all the global privileges
     to `'N''. It is assumed that you will grant specific privileges to
     the account later.

   * The statements that create accounts with no password will fail if
     the `NO_AUTO_CREATE_USER' SQL mode is enabled. To deal with this,
     use an `IDENTIFIED BY' clause that specifies a non-empty password.

As an alternative to `GRANT', you can create the same accounts directly
by issuing `INSERT' statements and then telling the server to reload
the grant tables using `FLUSH PRIVILEGES':

     shell> mysql --user=root mysql
     mysql> INSERT INTO user
         ->     VALUES('localhost','monty',PASSWORD('some_pass'),
         ->     'Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y');
     mysql> INSERT INTO user
         ->     VALUES('%','monty',PASSWORD('some_pass'),
         ->     'Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y',
         ->     'Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y',
         ->     '','','','',0,0,0,0);
     mysql> INSERT INTO user SET Host='localhost',User='admin',
         ->     Reload_priv='Y', Process_priv='Y';
     mysql> INSERT INTO user (Host,User,Password)
         ->     VALUES('localhost','dummy','');
     mysql> FLUSH PRIVILEGES;

The reason for using `FLUSH PRIVILEGES' when you create accounts with
`INSERT' is to tell the server to re-read the grant tables. Otherwise,
the changes go unnoticed until you restart the server. With `GRANT',
`FLUSH PRIVILEGES' is unnecessary.

The reason for using the `PASSWORD()' function with `INSERT' is to
encrypt the password. The `GRANT' statement encrypts the password for
you, so `PASSWORD()' is unnecessary.

The `'Y'' values enable privileges for the accounts. Depending on your
MySQL version, you may have to use a different number of `'Y'' values
in the first two `INSERT' statements. For the `admin' account, you may
also employ the more readable extended `INSERT' syntax using `SET'.

In the `INSERT' statement for the `dummy' account, only the `Host',
`User', and `Password' columns in the `user' table row are assigned
values. None of the privilege columns are set explicitly, so MySQL
assigns them all the default value of `'N''. This is equivalent to what
`GRANT USAGE' does.

If strict SQL mode is enabled, all columns that have no default value
must have a value specified. In this case, `INSERT' statements must
explicitly specify values for the `ssl_cipher', `x509_issuer', and
`x509_subject' columns.

Note that to set up a superuser account, it is necessary only to create
a `user' table entry with the privilege columns set to `'Y''. `user'
table privileges are global, so no entries in any of the other grant
tables are needed.

The next examples create three accounts and give them access to
specific databases. Each of them has a username of `custom' and
password of `obscure'.

To create the accounts with `GRANT', use the following statements:

     shell> mysql --user=root mysql
     mysql> GRANT SELECT,INSERT,UPDATE,DELETE,CREATE,DROP
         ->     ON bankaccount.*
         ->     TO 'custom'@'localhost'
         ->     IDENTIFIED BY 'obscure';
     mysql> GRANT SELECT,INSERT,UPDATE,DELETE,CREATE,DROP
         ->     ON expenses.*
         ->     TO 'custom'@'whitehouse.gov'
         ->     IDENTIFIED BY 'obscure';
     mysql> GRANT SELECT,INSERT,UPDATE,DELETE,CREATE,DROP
         ->     ON customer.*
         ->     TO 'custom'@'server.domain'
         ->     IDENTIFIED BY 'obscure';

The three accounts can be used as follows:

   * The first account can access the `bankaccount' database, but only
     from the local host.

   * The second account can access the `expenses' database, but only
     from the host `whitehouse.gov'.

   * The third account can access the `customer' database, but only
     from the host `server.domain'.

To set up the `custom' accounts without `GRANT', use `INSERT'
statements as follows to modify the grant tables directly:

     shell> mysql --user=root mysql
     mysql> INSERT INTO user (Host,User,Password)
         ->     VALUES('localhost','custom',PASSWORD('obscure'));
     mysql> INSERT INTO user (Host,User,Password)
         ->     VALUES('whitehouse.gov','custom',PASSWORD('obscure'));
     mysql> INSERT INTO user (Host,User,Password)
         ->     VALUES('server.domain','custom',PASSWORD('obscure'));
     mysql> INSERT INTO db
         ->     (Host,Db,User,Select_priv,Insert_priv,
         ->     Update_priv,Delete_priv,Create_priv,Drop_priv)
         ->     VALUES('localhost','bankaccount','custom',
         ->     'Y','Y','Y','Y','Y','Y');
     mysql> INSERT INTO db
         ->     (Host,Db,User,Select_priv,Insert_priv,
         ->     Update_priv,Delete_priv,Create_priv,Drop_priv)
         ->     VALUES('whitehouse.gov','expenses','custom',
         ->     'Y','Y','Y','Y','Y','Y');
     mysql> INSERT INTO db
         ->     (Host,Db,User,Select_priv,Insert_priv,
         ->     Update_priv,Delete_priv,Create_priv,Drop_priv)
         ->     VALUES('server.domain','customer','custom',
         ->     'Y','Y','Y','Y','Y','Y');
     mysql> FLUSH PRIVILEGES;

The first three `INSERT' statements add `user' table entries that allow
the user `custom' to connect from the various hosts with the given
password, but grant no global privileges (all privileges are set to the
default value of `'N''). The next three `INSERT' statements add `db'
table entries that grant privileges to `custom' for the `bankaccount',
`expenses', and `customer' databases, but only when accessed from the
proper hosts. As usual when you modify the grant tables directly, you
must tell the server to reload them with `FLUSH PRIVILEGES' so that the
privilege changes take effect.

If you want to give a specific user access from all machines in a given
domain (for example, `mydomain.com'), you can issue a `GRANT' statement
that uses the ``%'' wildcard character in the host part of the account
name:

     mysql> GRANT ...
         ->     ON *.*
         ->     TO 'myname'@'%.mydomain.com'
         ->     IDENTIFIED BY 'mypass';

To do the same thing by modifying the grant tables directly, do this:

     mysql> INSERT INTO user (Host,User,Password,...)
         ->     VALUES('%.mydomain.com','myname',PASSWORD('mypass'),...);
     mysql> FLUSH PRIVILEGES;


File: manual.info,  Node: removing-users,  Next: user-resources,  Prev: adding-users,  Up: user-account-management

5.5.3 Removing User Accounts from MySQL
---------------------------------------

To remove an account, use the `DROP USER' statement, which is described
in *Note drop-user::.


File: manual.info,  Node: user-resources,  Next: passwords,  Prev: removing-users,  Up: user-account-management

5.5.4 Limiting Account Resources
--------------------------------

One means of limiting use of MySQL server resources is to set the
`max_user_connections' system variable to a non-zero value. However,
this method is strictly global, and does not allow for management of
individual accounts. In addition, it limits only the number of
simultaneous connections made using a single account, and not what a
client can do once connected. Both types of control are of interest to
many MySQL administrators, particularly those working for Internet
Service Providers.

In MySQL 5.1, you can limit the following server resources for
individual accounts:

   * The number of queries that an account can issue per hour

   * The number of updates that an account can issue per hour

   * The number of times an account can connect to the server per hour

Any statement that a client can issue counts against the query limit.
Only statements that modify databases or tables count against the
update limit.

It is also possible to limit the number of simultaneous connections to
the server on a per-account basis.

An `account' in this context is assessed as a single row in the `user'
table. That is, connections are assessed against the `Host' value in
the `user' table row that applies to the connection. Suppose that there
is a row in the `user' table that has `User' and `Host' values of
`usera' and `%.example.com', to allow `usera' to connect from any host
in the `example.com' domain. In this case, the server applies resource
limits collectively to all connections by `usera' from any host in the
`example.com' domain.

Before MySQL 5.0.3, an `account' was assessed against the actual host
from which a user connects. This older method accounting may be
selected by starting the server with the `--old-style-user-limits'
option. In this case, if `usera' connects simultaneously from
`host1.example.com' and `host2.example.com', the server applies the
account resource limits separately to each connection. If `usera'
connects again from `host1.example.com', the server applies the limits
for that connection together with the existing connection from that
host.

As a prerequisite for using this feature, the `user' table in the
`mysql' database must contain the resource-related columns. Resource
limits are stored in the `max_questions', `max_updates',
`max_connections', and `max_user_connections' columns. If your `user'
table doesn't have these columns, it must be upgraded; see *Note
mysql-upgrade::.

To set resource limits with a `GRANT' statement, use a `WITH' clause
that names each resource to be limited and a per-hour count indicating
the limit value. For example, to create a new account that can access
the `customer' database, but only in a limited fashion, issue this
statement:

     mysql> GRANT ALL ON customer.* TO 'francis'@'localhost'
         ->     IDENTIFIED BY 'frank'
         ->     WITH MAX_QUERIES_PER_HOUR 20
         ->          MAX_UPDATES_PER_HOUR 10
         ->          MAX_CONNECTIONS_PER_HOUR 5
         ->          MAX_USER_CONNECTIONS 2;

The limit types need not all be named in the `WITH' clause, but those
named can be present in any order. The value for each per-hour limit
should be an integer representing a count per hour. If the `GRANT'
statement has no `WITH' clause, the limits are each set to the default
value of zero (that is, no limit). For `MAX_USER_CONNECTIONS', the
limit is an integer indicating the maximum number of simultaneous
connections the account can make at any one time. If the limit is set
to the default value of zero, the `max_user_connections' system variable
determines the number of simultaneous connections for the account.

To set or change limits for an existing account, use a `GRANT USAGE'
statement at the global level (`ON *.*'). The following statement
changes the query limit for `francis' to 100:

     mysql> GRANT USAGE ON *.* TO 'francis'@'localhost'
         ->     WITH MAX_QUERIES_PER_HOUR 100;

This statement leaves the account's existing privileges unchanged and
modifies only the limit values specified.

To remove an existing limit, set its value to zero. For example, to
remove the limit on how many times per hour `francis' can connect, use
this statement:

     mysql> GRANT USAGE ON *.* TO 'francis'@'localhost'
         ->     WITH MAX_CONNECTIONS_PER_HOUR 0;

Resource-use counting takes place when any account has a non-zero limit
placed on its use of any of the resources.

As the server runs, it counts the number of times each account uses
resources. If an account reaches its limit on number of connections
within the last hour, further connections for the account are rejected
until that hour is up. Similarly, if the account reaches its limit on
the number of queries or updates, further queries or updates are
rejected until the hour is up. In all such cases, an appropriate error
message is issued.

Resource counting is done per account, not per client. For example, if
your account has a query limit of 50, you cannot increase your limit to
100 by making two simultaneous client connections to the server.
Queries issued on both connections are counted together.

Queries for which results are served from the query cache do not count
against the `MAX_QUERIES_PER_HOUR' limit.

The current per-hour resource-use counts can be reset globally for all
accounts, or individually for a given account:

   * To reset the current counts to zero for all accounts, issue a
     `FLUSH USER_RESOURCES' statement. The counts also can be reset by
     reloading the grant tables (for example, with a `FLUSH PRIVILEGES'
     statement or a `mysqladmin reload' command).

   * The counts for an individual account can be set to zero by
     re-granting it any of its limits. To do this, use `GRANT USAGE' as
     described earlier and specify a limit value equal to the value
     that the account currently has.

Counter resets do not affect the `MAX_USER_CONNECTIONS' limit.

All counts begin at zero when the server starts; counts are not carried
over through a restart.


File: manual.info,  Node: passwords,  Next: password-security,  Prev: user-resources,  Up: user-account-management

5.5.5 Assigning Account Passwords
---------------------------------

Passwords may be assigned from the command line by using the
`mysqladmin' command:

     shell> mysqladmin -u USER_NAME -h HOST_NAME password "NEWPWD"

The account for which this command resets the password is the one with
a `user' table row that matches USER_NAME in the `User' column and the
client host _from which you connect_ in the `Host' column.

Another way to assign a password to an account is to issue a `SET
PASSWORD' statement:

     mysql> SET PASSWORD FOR 'jeffrey'@'%' = PASSWORD('biscuit');

Only users such as `root' that have update access to the `mysql'
database can change the password for other users. If you are not
connected as an anonymous user, you can change your own password by
omitting the `FOR' clause:

     mysql> SET PASSWORD = PASSWORD('biscuit');

You can also use a `GRANT USAGE' statement at the global level (`ON
*.*') to assign a password to an account without affecting the
account's current privileges:

     mysql> GRANT USAGE ON *.* TO 'jeffrey'@'%' IDENTIFIED BY 'biscuit';

Although it is generally preferable to assign passwords using one of
the preceding methods, you can also do so by modifying the `user' table
directly:

   * To establish a password when creating a new account, provide a
     value for the `Password' column:

          shell> mysql -u root mysql
          mysql> INSERT INTO user (Host,User,Password)
              -> VALUES('%','jeffrey',PASSWORD('biscuit'));
          mysql> FLUSH PRIVILEGES;

   * To change the password for an existing account, use `UPDATE' to
     set the `Password' column value:

          shell> mysql -u root mysql
          mysql> UPDATE user SET Password = PASSWORD('bagel')
              -> WHERE Host = '%' AND User = 'francis';
          mysql> FLUSH PRIVILEGES;

When you assign an account a non-empty password using `SET PASSWORD',
`INSERT', or `UPDATE', you must use the `PASSWORD()' function to encrypt
it. `PASSWORD()' is necessary because the `user' table stores passwords
in encrypted form, not as plaintext. If you forget that fact, you are
likely to set passwords like this:

     shell> mysql -u root mysql
     mysql> INSERT INTO user (Host,User,Password)
         -> VALUES('%','jeffrey','biscuit');
     mysql> FLUSH PRIVILEGES;

The result is that the literal value `'biscuit'' is stored as the
password in the `user' table, not the encrypted value. When `jeffrey'
attempts to connect to the server using this password, the value is
encrypted and compared to the value stored in the `user' table.
However, the stored value is the literal string `'biscuit'', so the
comparison fails and the server rejects the connection:

     shell> mysql -u jeffrey -pbiscuit test
     Access denied

If you assign passwords using the `GRANT ... IDENTIFIED BY' statement
or the `mysqladmin password' command, they both take care of encrypting
the password for you. In these cases, using `PASSWORD()' function is
unnecessary.

*Note*:

`PASSWORD()' encryption is different from Unix password encryption. See
*Note user-names::.


File: manual.info,  Node: password-security,  Next: secure-connections,  Prev: passwords,  Up: user-account-management

5.5.6 Keeping Your Password Secure
----------------------------------

On an administrative level, you should never grant access to the `user'
grant table to any non-administrative accounts.

When you run a client program to connect to the MySQL server, it is
inadvisable to specify your password in a way that exposes it to
discovery by other users. The methods you can use to specify your
password when you run client programs are listed here, along with an
assessment of the risks of each method:

   * Use a `-pYOUR_PASS' or `--password=YOUR_PASS' option on the
     command line. For example:

          shell> mysql -u francis -pfrank DB_NAME

     This is convenient _but insecure_, because your password becomes
     visible to system status programs such as `ps' that may be invoked
     by other users to display command lines. MySQL clients typically
     overwrite the command-line password argument with zeros during
     their initialization sequence. However, there is still a brief
     interval during which the value is visible.  On some systems this
     strategy is ineffective, anyway, and the password remains visible
     to `ps'.  (SystemV Unix systems and perhaps others are subject to
     this problem.)

   * Use the `-p' or `--password' option with no password value
     specified. In this case, the client program solicits the password
     from the terminal:

          shell> mysql -u francis -p DB_NAME
          Enter password: ********

     The ``*'' characters indicate where you enter your password. The
     password is not displayed as you enter it.

     It is more secure to enter your password this way than to specify
     it on the command line because it is not visible to other users.
     However, this method of entering a password is suitable only for
     programs that you run interactively. If you want to invoke a
     client from a script that runs non-interactively, there is no
     opportunity to enter the password from the terminal. On some
     systems, you may even find that the first line of your script is
     read and interpreted (incorrectly) as your password.

   * Store your password in an option file. For example, on Unix you
     can list your password in the `[client]' section of the `.my.cnf'
     file in your home directory:

          [client]
          password=your_pass

     If you store your password in `.my.cnf', the file should not be
     accessible to anyone but yourself. To ensure this, set the file
     access mode to `400' or `600'. For example:

          shell> chmod 600 .my.cnf

     *Note option-files::, discusses option files in more detail.

   * Store your password in the `MYSQL_PWD' environment variable. This
     method of specifying your MySQL password must be considered
     _extremely insecure_ and should not be used. Some versions of `ps'
     include an option to display the environment of running processes.
     If you set `MYSQL_PWD', your password is exposed to any other user
     who runs `ps'. Even on systems without such a version of `ps', it
     is unwise to assume that there are no other methods by which users
     can examine process environments. See *Note
     environment-variables::.

All in all, the safest methods are to have the client program prompt
for the password or to specify the password in a properly protected
option file.


File: manual.info,  Node: secure-connections,  Prev: password-security,  Up: user-account-management

5.5.7 Using SSL for Secure Connections
--------------------------------------

* Menu:

* secure-basics::                Basic SSL Concepts
* secure-using-ssl::             Using SSL Connections
* ssl-options::                  SSL Command Options
* secure-create-certs::          Setting Up SSL Certificates for MySQL
* windows-and-ssh::              Connecting to MySQL Remotely from Windows with SSH

MySQL supports secure (encrypted) connections between MySQL clients and
the server using the Secure Sockets Layer (SSL) protocol. This section
discusses how to use SSL connections. It also describes a way to set up
SSH on Windows. For information on how to require users to use SSL
connections, see the discussion of the `REQUIRE' clause of the `GRANT'
statement in *Note grant::.

The standard configuration of MySQL is intended to be as fast as
possible, so encrypted connections are not used by default.  Doing so
would make the client/server protocol much slower.  Encrypting data is
a CPU-intensive operation that requires the computer to do additional
work and can delay other MySQL tasks.  For applications that require
the security provided by encrypted connections, the extra computation
is warranted.

MySQL allows encryption to be enabled on a per-connection basis.  You
can choose a normal unencrypted connection or a secure encrypted SSL
connection according the requirements of individual applications.

Secure connections are based on the OpenSSL API and are available
through the MySQL C API. Replication uses the C API, so secure
connections can be used between master and slave servers.


File: manual.info,  Node: secure-basics,  Next: secure-using-ssl,  Prev: secure-connections,  Up: secure-connections

5.5.7.1 Basic SSL Concepts
..........................

To understand how MySQL uses SSL, it is necessary to explain some basic
SSL and X509 concepts. People who are familiar with these can skip this
part of the discussion.

By default, MySQL uses unencrypted connections between the client and
the server. This means that someone with access to the network could
watch all your traffic and look at the data being sent or received.
They could even change the data while it is in transit between client
and server. To improve security a little, you can compress
client/server traffic by using the `--compress' option when invoking
client programs. However, this does not foil a determined attacker.

When you need to move information over a network in a secure fashion,
an unencrypted connection is unacceptable. Encryption is the way to
make any kind of data unreadable. In fact, today's practice requires
many additional security elements from encryption algorithms. They
should resist many kind of known attacks such as changing the order of
encrypted messages or replaying data twice.

SSL is a protocol that uses different encryption algorithms to ensure
that data received over a public network can be trusted. It has
mechanisms to detect any data change, loss, or replay. SSL also
incorporates algorithms that provide identity verification using the
X509 standard.

X509 makes it possible to identify someone on the Internet. It is most
commonly used in e-commerce applications. In basic terms, there should
be some company called a `Certificate Authority' (or CA) that assigns
electronic certificates to anyone who needs them. Certificates rely on
asymmetric encryption algorithms that have two encryption keys (a
public key and a secret key). A certificate owner can show the
certificate to another party as proof of identity. A certificate
consists of its owner's public key.  Any data encrypted with this
public key can be decrypted only using the corresponding secret key,
which is held by the owner of the certificate.

If you need more information about SSL, X509, or encryption, use your
favorite Internet search engine to search for the keywords in which you
are interested.


File: manual.info,  Node: secure-using-ssl,  Next: ssl-options,  Prev: secure-basics,  Up: secure-connections

5.5.7.2 Using SSL Connections
.............................

To use SSL connections between the MySQL server and client programs,
your system must support either OpenSSL or yaSSL and your version of
MySQL must be built with SSL support.

To make it easier to use secure connections, MySQL is bundled with
yaSSL. (MySQL and yaSSL employ the same licensing model, whereas
OpenSSL uses an Apache-style license.) yaSSL support initially was
available only for a few platforms, but now it is available on all
platforms supported by MySQL AB.

To get secure connections to work with MySQL and SSL, you must do the
following:

  1. If you are not using a binary (precompiled) version of MySQL that
     has been built with SSL support, and you are going to use OpenSSL
     rather than the bundled yaSSL library, install OpenSSL if it has
     not already been installed. We have tested MySQL with OpenSSL
     0.9.6. To obtain OpenSSL, visit `http://www.openssl.org'.

  2. If you are not using a binary (precompiled) version of MySQL that
     has been built with SSL support, configure a MySQL source
     distribution to use SSL. When you configure MySQL, invoke the
     `configure' script like this:

          shell> ./configure --with-ssl

     That configures the distribution to use the bundled yaSSL library.
     To use OpenSSL instead, specify the `--with-ssl' option with the
     path to the directory where the OpenSSL header files and libraries
     are located:

          shell> ./configure --with-ssl=PATH

     Before MySQL 5.1.11, you must use the appropriate option to select
     the SSL library that you want to use.

     For yaSSL:

          shell> ./configure --with-yassl

     For OpenSSL:

          shell> ./configure --with-openssl

     Note that yaSSL support on Unix platforms requires that either
     `/dev/urandom' or `/dev/random' be available to retrieve true
     random numbers. For additional information (especially regarding
     yaSSL on Solaris versions prior to 2.8 and HP-UX), see Bug#13164
     (http://bugs.mysql.com/13164).

  3. Make sure that you have upgraded your grant tables to include the
     SSL-related columns in the `mysql.user' table. This is necessary if
     your grant tables date from a version of MySQL older than 4.0. The
     upgrade procedure is described in *Note mysql-upgrade::.

  4. To check whether a server binary is compiled with SSL support,
     invoke it with the `--ssl' option.  An error will occur if the
     server does not support SSL:

          shell> mysqld --ssl --help
          060525 14:18:52 [ERROR] mysqld: unknown option '--ssl'

     To check whether a running `mysqld' server supports SSL, examine
     the value of the `have_ssl' system variable:

          mysql> SHOW VARIABLES LIKE 'have_ssl';
          +---------------+-------+
          | Variable_name | Value |
          +---------------+-------+
          | have_ssl      | YES   |
          +---------------+-------+

     If the value is `YES', the server supports SSL connections. If the
     value is `DISABLED', the server supports SSL connections but was
     not started with the appropriate `--ssl-XXX' options (described
     later in this section). If the value is `YES', the server supports
     SSL connections.

To enable SSL connections, the proper SSL-related command options must
be used (see *Note ssl-options::).

To start the MySQL server so that it allows clients to connect via SSL,
use the options that identify the key and certificate files the server
needs when establishing a secure connection:

     shell> mysqld --ssl-ca=CACERT.PEM \
            --ssl-cert=SERVER-CERT.PEM \
            --ssl-key=SERVER-KEY.PEM

   * `--ssl-ca' identifies the Certificate Authority (CA) certificate.

   * `--ssl-cert' identifies the server public key. This can be sent to
     the client and authenticated against the CA certificate that it
     has.

   * `--ssl-key' identifies the server private key.

To establish a secure connection to a MySQL server with SSL support,
the options that a client must specify depend on the SSL requirements
of the user account that the client uses.  (See the discussion of the
`REQUIRE' clause in *Note grant::.)

If the account has no special SSL requirements or was created using a
`GRANT' statement that includes the `REQUIRE SSL' option, a client can
connect securely by using just the `--ssl-ca' option:

     shell> mysql --ssl-ca=CACERT.PEM

To require that a client certificate also be specified, create the
account using the `REQUIRE X509' option.  Then the client must also
specify the proper client key and certificate files or the server will
reject the connection:

     shell> mysql --ssl-ca=CACERT.PEM \
            --ssl-cert=CLIENT-CERT.PEM \
            --ssl-key=CLIENT-KEY.PEM

In other words, the options are similar to those used for the server.
Note that the Certificate Authority certificate has to be the same.

A client can determine whether the current connection with the server
uses SSL by checking the value of the `Ssl_cipher' status variable. The
value of `Ssl_cipher' is non-empty if SSL is used, and empty otherwise.
For example:

     mysql> SHOW STATUS LIKE 'Ssl_cipher';
     +---------------+--------------------+
     | Variable_name | Value              |
     +---------------+--------------------+
     | Ssl_cipher    | DHE-RSA-AES256-SHA |
     +---------------+--------------------+

For the `mysql' client, you can use the `STATUS' or `\s' command and
check the `SSL' line:

     mysql> \s
     ...
     SSL:                    Not in use
     ...

Or:

     mysql> \s
     ...
     SSL:                    Cipher in use is DHE-RSA-AES256-SHA
     ...

To establish a secure connection from within an application program,
use the *Note `mysql_ssl_set()': mysql-ssl-set. C API function to set
the appropriate certificate options before calling *Note
`mysql_real_connect()': mysql-real-connect.  See *Note mysql-ssl-set::.
After the connection is established, you can use *Note
`mysql_get_ssl_cipher()': mysql-get-ssl-cipher. to determine whether
SSL is in use. A non-`NULL' return value indicates a secure connection
and names the SSL cipher used for encryption. A `NULL' return value
indicates that SSL is not being used. See *Note mysql-get-ssl-cipher::.


File: manual.info,  Node: ssl-options,  Next: secure-create-certs,  Prev: secure-using-ssl,  Up: secure-connections

5.5.7.3 SSL Command Options
...........................

The following list describes options that are used for specifying the
use of SSL, certificate files, and key files.  They can be given on the
command line or in an option file.  These options are not available
unless MySQL has been built with SSL support. See *Note
secure-using-ssl::.  (There are also `--master-ssl*' options that can
be used for setting up a secure connection from a slave replication
server to a master server; see *Note replication-options::.)

*Name*                        *Cmd-Line*                                                 *Option file*                                              *System Var*                                               *Status Var*                                               *Var Scope*                                                *Dynamic*
have_openssl                                                                                                                                        Yes                                                                                                                   Global                                                     No
have_ssl                                                                                                                                            Yes                                                                                                                   Global                                                     No
skip-ssl                      Yes                                                        Yes                                                                                                                                                                                                                                         
ssl                           Yes                                                        Yes                                                                                                                                                                                                                                         
ssl-ca                        Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: ssl_ca                                                                                                                                Yes                                                                                                                   Global                                                     No
ssl-capath                    Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: ssl_capath                                                                                                                            Yes                                                                                                                   Global                                                     No
ssl-cert                      Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: ssl_cert                                                                                                                              Yes                                                                                                                   Global                                                     No
ssl-cipher                    Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: ssl_cipher                                                                                                                            Yes                                                                                                                   Global                                                     No
ssl-key                       Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_: ssl_key                                                                                                                               Yes                                                                                                                   Global                                                     No
ssl-verify-server-cert        Yes                                                        Yes                                                                                                                                                                                                                                         

   * `--ssl'

     For the server, this option specifies that the server allows SSL
     connections. For a client program, it allows the client to connect
     to the server using SSL. This option is not sufficient in itself
     to cause an SSL connection to be used. You must also specify the
     `--ssl-ca' option, and possibly the `--ssl-cert' and `--ssl-key'
     options.

     This option is more often used in its opposite form to override
     any other SSL options and indicate that SSL should _not_ be used.
     To do this, specify the option as `--skip-ssl' or `--ssl=0'.

     Note that use of `--ssl' does not _require_ an SSL connection. For
     example, if the server or client is compiled without SSL support,
     a normal unencrypted connection is used.

     The secure way to require use of an SSL connection is to create an
     account on the server that includes a `REQUIRE SSL' clause in the
     `GRANT' statement. Then use that account to connect to the server,
     where both the server and the client have SSL support enabled.

     The `REQUIRE' clause allows other SSL-related restrictions as
     well. The description of `REQUIRE' in *Note grant::, provides
     additional detail about which SSL command options may or must be
     specified by clients that connect using accounts that are created
     using the various `REQUIRE' options.

   * `--ssl-ca=FILE_NAME'

     The path to a file that contains a list of trusted SSL CAs.

   * `--ssl-capath=DIRECTORY_NAME'

     The path to a directory that contains trusted SSL CA certificates
     in PEM format.

   * `--ssl-cert=FILE_NAME'

     The name of the SSL certificate file to use for establishing a
     secure connection.

   * `--ssl-cipher=CIPHER_LIST'

     A list of allowable ciphers to use for SSL encryption. For
     greatest portability, CIPHER_LIST should be a list of one or more
     cipher names, separated by colons. Examples:

          --ssl-cipher=AES128-SHA
          --ssl-cipher=DHE-RSA-AES256-SHA:AES128-SHA

     This format is understood both by OpenSSL and yaSSL.  OpenSSL
     supports a more flexible syntax for specifying ciphers, as
     described in the OpenSSL documentation at
     `http://www.openssl.org/docs/apps/ciphers.html'.  However, this
     extended syntax will fail if used with a MySQL installation
     compiled against yaSSL.

     If no cipher in the list is supported, SSL connections will not
     work.

   * `--ssl-key=FILE_NAME'

     The name of the SSL key file to use for establishing a secure
     connection.

   *  `--ssl-verify-server-cert'

     This option is available for client programs. It causes the
     server's Common Name value in the certificate that the server
     sends to the client to be verified against the hostname that the
     client uses for connecting to the server, and the connection is
     rejected if there is a mismatch. This feature can be used to
     prevent man-in-the-middle attacks. Verification is disabled by
     default. This option was added in MySQL 5.1.11.

As of MySQL 5.1.18, if you use SSL when establishing a client
connection, you can tell the client not to authenticate the server
certificate by specifying neither `--ssl-ca' nor `--ssl-capath'.  The
server still verifies the client according to any applicable
requirements established via `GRANT' statements for the client, and it
still uses any `--ssl-ca'/`--ssl-capath' values that were passed to
server at startup time.


File: manual.info,  Node: secure-create-certs,  Next: windows-and-ssh,  Prev: ssl-options,  Up: secure-connections

5.5.7.4 Setting Up SSL Certificates for MySQL
.............................................

This section demonstrates how to set up SSL certificate and key files
for use by MySQL servers and clients. The first example shows a
simplified procedure such as you might use from the command line. The
second shows a script that contains more detail. Both examples use the
`openssl' command that is part of OpenSSL.

The following example shows a set of commands to create MySQL server
and client certificate and key files. You will need to respond to
several prompts by the `openssl' commands. For testing, you can press
Enter to all prompts. For production use, you should provide non-empty
responses.

     # Create clean environment
     shell> rm -rf newcerts
     shell> mkdir newcerts && cd newcerts

     # Create CA certificate
     shell> openssl genrsa 2048 > ca-key.pem
     shell> openssl req -new -x509 -nodes -days 1000 \
              -key ca-key.pem > ca-cert.pem

     # Create server certificate
     shell> openssl req -newkey rsa:2048 -days 1000 \
              -nodes -keyout server-key.pem > server-req.pem
     shell> openssl x509 -req -in server-req.pem -days 1000 \
              -CA ca-cert.pem -CAkey ca-key.pem -set_serial 01 > server-cert.pem

     # Create client certificate
     shell> openssl req -newkey rsa:2048 -days 1000 \
              -nodes -keyout client-key.pem > client-req.pem
     shell> openssl x509 -req -in client-req.pem -days 1000 \
              -CA ca-cert.pem -CAkey ca-key.pem -set_serial 01 > client-cert.pem

Here is an example script that shows how to set up SSL certificates for
MySQL:

     DIR=`pwd`/openssl
     PRIV=$DIR/private

     mkdir $DIR $PRIV $DIR/newcerts
     cp /usr/share/ssl/openssl.cnf $DIR
     replace ./demoCA $DIR -- $DIR/openssl.cnf

     # Create necessary files: $database, $serial and $new_certs_dir
     # directory (optional)

     touch $DIR/index.txt
     echo "01" > $DIR/serial

     #
     # Generation of Certificate Authority(CA)
     #

     openssl req -new -x509 -keyout $PRIV/cakey.pem -out $DIR/cacert.pem \
         -config $DIR/openssl.cnf

     # Sample output:
     # Using configuration from /home/monty/openssl/openssl.cnf
     # Generating a 1024 bit RSA private key
     # ................++++++
     # .........++++++
     # writing new private key to '/home/monty/openssl/private/cakey.pem'
     # Enter PEM pass phrase:
     # Verifying password - Enter PEM pass phrase:
     # -----
     # You are about to be asked to enter information that will be
     # incorporated into your certificate request.
     # What you are about to enter is what is called a Distinguished Name
     # or a DN.
     # There are quite a few fields but you can leave some blank
     # For some fields there will be a default value,
     # If you enter '.', the field will be left blank.
     # -----
     # Country Name (2 letter code) [AU]:FI
     # State or Province Name (full name) [Some-State]:.
     # Locality Name (eg, city) []:
     # Organization Name (eg, company) [Internet Widgits Pty Ltd]:MySQL AB
     # Organizational Unit Name (eg, section) []:
     # Common Name (eg, YOUR name) []:MySQL admin
     # Email Address []:

     #
     # Create server request and key
     #
     openssl req -new -keyout $DIR/server-key.pem -out \
         $DIR/server-req.pem -days 3600 -config $DIR/openssl.cnf

     # Sample output:
     # Using configuration from /home/monty/openssl/openssl.cnf
     # Generating a 1024 bit RSA private key
     # ..++++++
     # ..........++++++
     # writing new private key to '/home/monty/openssl/server-key.pem'
     # Enter PEM pass phrase:
     # Verifying password - Enter PEM pass phrase:
     # -----
     # You are about to be asked to enter information that will be
     # incorporated into your certificate request.
     # What you are about to enter is what is called a Distinguished Name
     # or a DN.
     # There are quite a few fields but you can leave some blank
     # For some fields there will be a default value,
     # If you enter '.', the field will be left blank.
     # -----
     # Country Name (2 letter code) [AU]:FI
     # State or Province Name (full name) [Some-State]:.
     # Locality Name (eg, city) []:
     # Organization Name (eg, company) [Internet Widgits Pty Ltd]:MySQL AB
     # Organizational Unit Name (eg, section) []:
     # Common Name (eg, YOUR name) []:MySQL server
     # Email Address []:
     #
     # Please enter the following 'extra' attributes
     # to be sent with your certificate request
     # A challenge password []:
     # An optional company name []:

     #
     # Remove the passphrase from the key
     #
     openssl rsa -in $DIR/server-key.pem -out $DIR/server-key.pem

     #
     # Sign server cert
     #
     openssl ca  -policy policy_anything -out $DIR/server-cert.pem \
         -config $DIR/openssl.cnf -infiles $DIR/server-req.pem

     # Sample output:
     # Using configuration from /home/monty/openssl/openssl.cnf
     # Enter PEM pass phrase:
     # Check that the request matches the signature
     # Signature ok
     # The Subjects Distinguished Name is as follows
     # countryName           :PRINTABLE:'FI'
     # organizationName      :PRINTABLE:'MySQL AB'
     # commonName            :PRINTABLE:'MySQL admin'
     # Certificate is to be certified until Sep 13 14:22:46 2003 GMT
     # (365 days)
     # Sign the certificate? [y/n]:y
     #
     #
     # 1 out of 1 certificate requests certified, commit? [y/n]y
     # Write out database with 1 new entries
     # Data Base Updated

     #
     # Create client request and key
     #
     openssl req -new -keyout $DIR/client-key.pem -out \
         $DIR/client-req.pem -days 3600 -config $DIR/openssl.cnf

     # Sample output:
     # Using configuration from /home/monty/openssl/openssl.cnf
     # Generating a 1024 bit RSA private key
     # .....................................++++++
     # .............................................++++++
     # writing new private key to '/home/monty/openssl/client-key.pem'
     # Enter PEM pass phrase:
     # Verifying password - Enter PEM pass phrase:
     # -----
     # You are about to be asked to enter information that will be
     # incorporated into your certificate request.
     # What you are about to enter is what is called a Distinguished Name
     # or a DN.
     # There are quite a few fields but you can leave some blank
     # For some fields there will be a default value,
     # If you enter '.', the field will be left blank.
     # -----
     # Country Name (2 letter code) [AU]:FI
     # State or Province Name (full name) [Some-State]:.
     # Locality Name (eg, city) []:
     # Organization Name (eg, company) [Internet Widgits Pty Ltd]:MySQL AB
     # Organizational Unit Name (eg, section) []:
     # Common Name (eg, YOUR name) []:MySQL user
     # Email Address []:
     #
     # Please enter the following 'extra' attributes
     # to be sent with your certificate request
     # A challenge password []:
     # An optional company name []:

     #
     # Remove the passphrase from the key
     #
     openssl rsa -in $DIR/client-key.pem -out $DIR/client-key.pem

     #
     # Sign client cert
     #

     openssl ca  -policy policy_anything -out $DIR/client-cert.pem \
         -config $DIR/openssl.cnf -infiles $DIR/client-req.pem

     # Sample output:
     # Using configuration from /home/monty/openssl/openssl.cnf
     # Enter PEM pass phrase:
     # Check that the request matches the signature
     # Signature ok
     # The Subjects Distinguished Name is as follows
     # countryName           :PRINTABLE:'FI'
     # organizationName      :PRINTABLE:'MySQL AB'
     # commonName            :PRINTABLE:'MySQL user'
     # Certificate is to be certified until Sep 13 16:45:17 2003 GMT
     # (365 days)
     # Sign the certificate? [y/n]:y
     #
     #
     # 1 out of 1 certificate requests certified, commit? [y/n]y
     # Write out database with 1 new entries
     # Data Base Updated

     #
     # Create a my.cnf file that you can use to test the certificates
     #

     cnf=""
     cnf="$cnf [client]"
     cnf="$cnf ssl-ca=$DIR/cacert.pem"
     cnf="$cnf ssl-cert=$DIR/client-cert.pem"
     cnf="$cnf ssl-key=$DIR/client-key.pem"
     cnf="$cnf [mysqld]"
     cnf="$cnf ssl-ca=$DIR/cacert.pem"
     cnf="$cnf ssl-cert=$DIR/server-cert.pem"
     cnf="$cnf ssl-key=$DIR/server-key.pem"
     echo $cnf | replace " " '
     ' > $DIR/my.cnf

To test SSL connections, start the server as follows, where `$DIR' is
the pathname to the directory where the sample `my.cnf' option file is
located:

     shell> mysqld --defaults-file=$DIR/my.cnf &

Then invoke a client program using the same option file:

     shell> mysql --defaults-file=$DIR/my.cnf

If you have a MySQL source distribution, you can also test your setup
by modifying the preceding `my.cnf' file to refer to the demonstration
certificate and key files in the `mysql-test/std_data' directory of the
distribution.


File: manual.info,  Node: windows-and-ssh,  Prev: secure-create-certs,  Up: secure-connections

5.5.7.5 Connecting to MySQL Remotely from Windows with SSH
..........................................................

Here is a note that describes how to get a secure connection to a
remote MySQL server with SSH (by David Carlson <dcarlson@mplcomm.com>):

  1. Install an SSH client on your Windows machine. As a user, the best
     non-free one I have found is from `SecureCRT' from
     `http://www.vandyke.com/'. Another option is `f-secure' from
     `http://www.f-secure.com/'. You can also find some free ones on
     `Google' at
     `http://directory.google.com/Top/Computers/Internet/Protocols/SSH/Clients/Windows/'.

  2. Start your Windows SSH client. Set `Host_Name =
     YOURMYSQLSERVER_URL_OR_IP'.  Set `userid=YOUR_USERID' to log in to
     your server. This `userid' value might not be the same as the
     username of your MySQL account.

  3. Set up port forwarding. Either do a remote forward (Set
     `local_port: 3306', `remote_host: YOURMYSQLSERVERNAME_OR_IP',
     `remote_port: 3306' ) or a local forward (Set `port: 3306', `host:
     localhost', `remote port: 3306').

  4. Save everything, otherwise you will have to redo it the next time.

  5. Log in to your server with the SSH session you just created.

  6. On your Windows machine, start some ODBC application (such as
     Access).

  7. Create a new file in Windows and link to MySQL using the ODBC
     driver the same way you normally do, except type in `localhost'
     for the MySQL host server, not YOURMYSQLSERVERNAME.

At this point, you should have an ODBC connection to MySQL, encrypted
using SSH.


File: manual.info,  Node: multiple-servers,  Prev: user-account-management,  Up: server-administration

5.6 Running Multiple MySQL Servers on the Same Machine
======================================================

* Menu:

* multiple-windows-servers::     Running Multiple Servers on Windows
* multiple-unix-servers::        Running Multiple Servers on Unix
* multiple-server-clients::      Using Client Programs in a Multiple-Server Environment

In some cases, you might want to run multiple `mysqld' servers on the
same machine. You might want to test a new MySQL release while leaving
your existing production setup undisturbed. Or you might want to give
different users access to different `mysqld' servers that they manage
themselves. (For example, you might be an Internet Service Provider
that wants to provide independent MySQL installations for different
customers.)

To run multiple servers on a single machine, each server must have
unique values for several operating parameters. These can be set on the
command line or in option files. See *Note program-options::.

At least the following options must be different for each server:

   * `--port=PORT_NUM'

     `--port' controls the port number for TCP/IP connections.
     (Alternatively, if the host has multiple network addresses, you
     can use `--bind-adress' to cause different servers to listen to
     different interfaces.)

   * `--socket=PATH'

     `--socket' controls the Unix socket file path on Unix and the name
     of the named pipe on Windows. On Windows, it is necessary to
     specify distinct pipe names only for those servers that support
     named-pipe connections.

   * `--shared-memory-base-name=NAME'

     This option currently is used only on Windows. It designates the
     shared-memory name used by a Windows server to allow clients to
     connect via shared memory. It is necessary to specify distinct
     shared-memory names only for those servers that support
     shared-memory connections.

   * `--pid-file=FILE_NAME'

     This option is used only on Unix. It indicates the pathname of the
     file in which the server writes its process ID.

If you use the following log file options, they must be different for
each server:

   * `--log=FILE_NAME'

   * `--log-bin=FILE_NAME'

   * `--log-update=FILE_NAME'

   * `--log-error=FILE_NAME'

*Note log-file-maintenance::, discusses the log file options further.

For better performance, you can specify the following options
differently for each server, to spread the load between several
physical disks:

   * `--tmpdir=PATH'

Having different temporary directories is also recommended to make it
easier to determine which MySQL server created any given temporary file.

With very limited exceptions, each server should use a different data
directory, which is specified using the `--datadir=PATH' option.

*Warning*:

Normally, you should never have two servers that update data in the
same databases. This may lead to unpleasant surprises if your operating
system does not support fault-free system locking. If (despite this
warning) you run multiple servers using the same data directory and
they have logging enabled, you must use the appropriate options to
specify log filenames that are unique to each server. Otherwise, the
servers try to log to the same files. Please note that this kind of
setup only works with `MyISAM' and `MERGE' tables, and not with any of
the other storage engines.

The warning against sharing a data directory among servers also applies
in an NFS environment. Allowing multiple MySQL servers to access a
common data directory over NFS is a _very bad idea_.

   * The primary problem is that NFS is the speed bottleneck. It is not
     meant for such use.

   * Another risk with NFS is that you must devise a way to ensure that
     two or more servers do not interfere with each other.  Usually NFS
     file locking is handled by the `lockd' daemon, but at the moment
     there is no platform that performs locking 100% reliably in every
     situation.

Make it easy for yourself: Forget about sharing a data directory among
servers over NFS. A better solution is to have one computer that
contains several CPUs and use an operating system that handles threads
efficiently.

If you have multiple MySQL installations in different locations, you
can specify the base installation directory for each server with the
`--basedir=PATH' option to cause each server to use a different data
directory, log files, and PID file. (The defaults for all these values
are determined relative to the base directory). In that case, the only
other options you need to specify are the `--socket' and `--port'
options. For example, suppose that you install different versions of
MySQL using `tar' file binary distributions. These install in different
locations, so you can start the server for each installation using the
command `bin/mysqld_safe' under its corresponding base directory.
`mysqld_safe' determines the proper `--basedir' option to pass to
`mysqld', and you need specify only the `--socket' and `--port' options
to `mysqld_safe'.

As discussed in the following sections, it is possible to start
additional servers by setting environment variables or by specifying
appropriate command-line options. However, if you need to run multiple
servers on a more permanent basis, it is more convenient to use option
files to specify for each server those option values that must be
unique to it. The `--defaults-file' option is useful for this purpose.


File: manual.info,  Node: multiple-windows-servers,  Next: multiple-unix-servers,  Prev: multiple-servers,  Up: multiple-servers

5.6.1 Running Multiple Servers on Windows
-----------------------------------------

* Menu:

* multiple-windows-command-line-servers::  Starting Multiple Windows Servers at the Command Line
* multiple-windows-services::    Starting Multiple Windows Servers as Services

You can run multiple servers on Windows by starting them manually from
the command line, each with appropriate operating parameters. On
Windows NT-based systems, you also have the option of installing
several servers as Windows services and running them that way. General
instructions for running MySQL servers from the command line or as
services are given in *Note windows-installation::. This section
describes how to make sure that you start each server with different
values for those startup options that must be unique per server, such
as the data directory. These options are described in *Note
multiple-servers::.


File: manual.info,  Node: multiple-windows-command-line-servers,  Next: multiple-windows-services,  Prev: multiple-windows-servers,  Up: multiple-windows-servers

5.6.1.1 Starting Multiple Windows Servers at the Command Line
.............................................................

To start multiple servers manually from the command line, you can
specify the appropriate options on the command line or in an option
file. It is more convenient to place the options in an option file, but
it is necessary to make sure that each server gets its own set of
options. To do this, create an option file for each server and tell the
server the filename with a `--defaults-file' option when you run it.

Suppose that you want to run `mysqld' on port 3307 with a data
directory of `C:\mydata1', and `mysqld-debug' on port 3308 with a data
directory of `C:\mydata2'. (To do this, make sure that before you start
the servers, each data directory exists and has its own copy of the
`mysql' database that contains the grant tables.) Then create two
option files. For example, create one file named `C:\my-opts1.cnf' that
looks like this:

     [mysqld]
     datadir = C:/mydata1
     port = 3307

Create a second file named `C:\my-opts2.cnf' that looks like this:

     [mysqld]
     datadir = C:/mydata2
     port = 3308

Then start each server with its own option file:

     C:\> C:\mysql\bin\mysqld --defaults-file=C:\my-opts1.cnf
     C:\> C:\mysql\bin\mysqld-debug --defaults-file=C:\my-opts2.cnf

On NT, each server starts in the foreground (no new prompt appears
until the server exits later), so you will need to issue those two
commands in separate console windows.

To shut down the servers, you must connect to each using the
appropriate port number:

     C:\> C:\mysql\bin\mysqladmin --port=3307 shutdown
     C:\> C:\mysql\bin\mysqladmin --port=3308 shutdown

Servers configured as just described allow clients to connect over
TCP/IP. If your version of Windows supports named pipes and you also
want to allow named-pipe connections, use the `mysqld-nt' (MySQL 5.1.20
and earlier), `mysqld' (MySQL 5.1.21 and later) or `mysqld-debug'
server and specify options that enable the named pipe and specify its
name. Each server that supports named-pipe connections must use a
unique pipe name. For example, the `C:\my-opts1.cnf' file might be
written like this:

     [mysqld]
     datadir = C:/mydata1
     port = 3307
     enable-named-pipe
     socket = mypipe1

Then start the server this way:

     C:\> C:\mysql\bin\mysqld --defaults-file=C:\my-opts1.cnf

Modify `C:\my-opts2.cnf' similarly for use by the second server.

A similar procedure applies for servers that you want to support
shared-memory connections. Enable such connections with the
`--shared-memory' option and specify a unique shared-memory name for
each server with the `--shared-memory-base-name' option.


File: manual.info,  Node: multiple-windows-services,  Prev: multiple-windows-command-line-servers,  Up: multiple-windows-servers

5.6.1.2 Starting Multiple Windows Servers as Services
.....................................................

On NT-based systems, a MySQL server can run as a Windows service. The
procedures for installing, controlling, and removing a single MySQL
service are described in *Note windows-start-service::.

You can also install multiple MySQL servers as services. In this case,
you must make sure that each server uses a different service name in
addition to all the other parameters that must be unique for each
server.

For the following instructions, assume that you want to run the
`mysqld' server from two different versions of MySQL that are installed
at `C:\mysql-5.0.19' and `C:\mysql-5.1.28', respectively.  (This might
be the case if you are running 5.0.19 as your production server, but
also want to conduct tests using 5.1.28.)

The following principles apply when installing a MySQL service with the
`--install' or `--install-manual' option:

   * If you specify no service name, the server uses the default
     service name of `MySQL' and the server reads options from the
     `[mysqld]' group in the standard option files.

   * If you specify a service name after the `--install' option, the
     server ignores the `[mysqld]' option group and instead reads
     options from the group that has the same name as the service. The
     server reads options from the standard option files.

   * If you specify a `--defaults-file' option after the service name,
     the server ignores the standard option files and reads options
     only from the `[mysqld]' group of the named file.

*Note*:

Before MySQL 4.0.17, only a server installed using the default service
name (`MySQL') or one installed explicitly with a service name of
`mysqld' will read the `[mysqld]' group in the standard option files.
As of 4.0.17, all servers read the `[mysqld]' group if they read the
standard option files, even if they are installed using another service
name. This allows you to use the `[mysqld]' group for options that
should be used by all MySQL services, and an option group named after
each service for use by the server installed with that service name.

Based on the preceding information, you have several ways to set up
multiple services. The following instructions describe some examples.
Before trying any of them, be sure that you shut down and remove any
existing MySQL services first.

   * *Approach 1:* Specify the options for all services in one of the
     standard option files. To do this, use a different service name
     for each server. Suppose that you want to run the 5.0.19 `mysqld'
     using the service name of `mysqld1' and the 5.1.28 `mysqld' using
     the service name `mysqld2'. In this case, you can use the
     `[mysqld1]' group for 5.0.19 and the `[mysqld2]' group for 5.1.28.
     For example, you can set up `C:\my.cnf' like this:

          # options for mysqld1 service
          [mysqld1]
          basedir = C:/mysql-5.0.19
          port = 3307
          enable-named-pipe
          socket = mypipe1

          # options for mysqld2 service
          [mysqld2]
          basedir = C:/mysql-5.1.28
          port = 3308
          enable-named-pipe
          socket = mypipe2

     Install the services as follows, using the full server pathnames
     to ensure that Windows registers the correct executable program
     for each service:

          C:\> C:\mysql-5.0.19\bin\mysqld --install mysqld1
          C:\> C:\mysql-5.1.28\bin\mysqld --install mysqld2

     To start the services, use the services manager, or use `NET
     START' with the appropriate service names:

          C:\> NET START mysqld1
          C:\> NET START mysqld2

     To stop the services, use the services manager, or use `NET STOP'
     with the appropriate service names:

          C:\> NET STOP mysqld1
          C:\> NET STOP mysqld2

   * *Approach 2:* Specify options for each server in separate files
     and use `--defaults-file' when you install the services to tell
     each server what file to use. In this case, each file should list
     options using a `[mysqld]' group.

     With this approach, to specify options for the 5.0.19 `mysqld-nt',
     create a file `C:\my-opts1.cnf' that looks like this:

          [mysqld]
          basedir = C:/mysql-5.0.19
          port = 3307
          enable-named-pipe
          socket = mypipe1

     For the 5.1.28 `mysqld', create a file `C:\my-opts2.cnf' that
     looks like this:

          [mysqld]
          basedir = C:/mysql-5.1.28
          port = 3308
          enable-named-pipe
          socket = mypipe2

     Install the services as follows (enter each command on a single
     line):

          C:\> C:\mysql-5.0.19\bin\mysqld --install mysqld1
                     --defaults-file=C:\my-opts1.cnf
          C:\> C:\mysql-5.1.28\bin\mysqld --install mysqld2
                     --defaults-file=C:\my-opts2.cnf

     To use a `--defaults-file' option when you install a MySQL server
     as a service, you must precede the option with the service name.

     After installing the services, start and stop them the same way as
     in the preceding example.

To remove multiple services, use `mysqld --remove' for each one,
specifying a service name following the `--remove' option. If the
service name is the default (`MySQL'), you can omit it.


File: manual.info,  Node: multiple-unix-servers,  Next: multiple-server-clients,  Prev: multiple-windows-servers,  Up: multiple-servers

5.6.2 Running Multiple Servers on Unix
--------------------------------------

The easiest way is to run multiple servers on Unix is to compile them
with different TCP/IP ports and Unix socket files so that each one is
listening on different network interfaces. Compiling in different base
directories for each installation also results automatically in a
separate, compiled-in data directory, log file, and PID file location
for each server.

Assume that an existing 5.0.19 server is configured for the default
TCP/IP port number (3306) and Unix socket file (`/tmp/mysql.sock'). To
configure a new 5.1.28 server to have different operating parameters,
use a `configure' command something like this:

     shell> ./configure --with-tcp-port=PORT_NUMBER \
                  --with-unix-socket-path=FILE_NAME \
                  --prefix=/usr/local/mysql-5.1.28

Here, PORT_NUMBER and FILE_NAME must be different from the default
TCP/IP port number and Unix socket file pathname, and the `--prefix'
value should specify an installation directory different from the one
under which the existing MySQL installation is located.

If you have a MySQL server listening on a given port number, you can
use the following command to find out what operating parameters it is
using for several important configurable variables, including the base
directory and Unix socket filename:

     shell> mysqladmin --host=HOST_NAME --port=PORT_NUMBER variables

With the information displayed by that command, you can tell what
option values _not_ to use when configuring an additional server.

Note that if you specify `localhost' as a hostname, `mysqladmin'
defaults to using a Unix socket file connection rather than TCP/IP.
From MySQL 4.1 onward, you can explicitly specify the connection
protocol to use by using the `--protocol={TCP|SOCKET|PIPE|MEMORY}'
option.

You don't have to compile a new MySQL server just to start with a
different Unix socket file and TCP/IP port number. It is also possible
to use the same server binary and start each invocation of it with
different parameter values at runtime. One way to do so is by using
command-line options:

     shell> mysqld_safe --socket=FILE_NAME --port=PORT_NUMBER

To start a second server, provide different `--socket' and `--port'
option values, and pass a `--datadir=PATH' option to `mysqld_safe' so
that the server uses a different data directory.

Another way to achieve a similar effect is to use environment variables
to set the Unix socket filename and TCP/IP port number:

     shell> MYSQL_UNIX_PORT=/tmp/mysqld-new.sock
     shell> MYSQL_TCP_PORT=3307
     shell> export MYSQL_UNIX_PORT MYSQL_TCP_PORT
     shell> mysql_install_db --user=mysql
     shell> mysqld_safe --datadir=/path/to/datadir &

This is a quick way of starting a second server to use for testing. The
nice thing about this method is that the environment variable settings
apply to any client programs that you invoke from the same shell. Thus,
connections for those clients are automatically directed to the second
server.

*Note environment-variables::, includes a list of other environment
variables you can use to affect `mysqld'.

For automatic server execution, the startup script that is executed at
boot time should execute the following command once for each server
with an appropriate option file path for each command:

     shell> mysqld_safe --defaults-file=FILE_NAME

Each option file should contain option values specific to a given
server.

On Unix, the `mysqld_multi' script is another way to start multiple
servers. See *Note mysqld-multi::.


File: manual.info,  Node: multiple-server-clients,  Prev: multiple-unix-servers,  Up: multiple-servers

5.6.3 Using Client Programs in a Multiple-Server Environment
------------------------------------------------------------

To connect with a client program to a MySQL server that is listening to
different network interfaces from those compiled into your client, you
can use one of the following methods:

   * Start the client with `--host=HOST_NAME --port=PORT_NUMBER' to
     connect via TCP/IP to a remote server, with `--host=127.0.0.1
     --port=PORT_NUMBER' to connect via TCP/IP to a local server, or
     with `--host=localhost --socket=FILE_NAME' to connect to a local
     server via a Unix socket file or a Windows named pipe.

   * As of MySQL 4.1, start the client with `--protocol=TCP' to connect
     via TCP/IP, `--protocol=SOCKET' to connect via a Unix socket file,
     `--protocol=PIPE' to connect via a named pipe, or
     `--protocol=MEMORY' to connect via shared memory. For TCP/IP
     connections, you may also need to specify `--host' and `--port'
     options. For the other types of connections, you may need to
     specify a `--socket' option to specify a Unix socket file or
     Windows named-pipe name, or a `--shared-memory-base-name' option
     to specify the shared-memory name. Shared-memory connections are
     supported only on Windows.

   * On Unix, set the `MYSQL_UNIX_PORT' and `MYSQL_TCP_PORT'
     environment variables to point to the Unix socket file and TCP/IP
     port number before you start your clients. If you normally use a
     specific socket file or port number, you can place commands to set
     these environment variables in your `.login' file so that they
     apply each time you log in. See *Note environment-variables::.

   * Specify the default Unix socket file and TCP/IP port number in the
     `[client]' group of an option file.  For example, you can use
     `C:\my.cnf' on Windows, or the `.my.cnf' file in your home
     directory on Unix. See *Note option-files::.

   * In a C program, you can specify the socket file or port number
     arguments in the *Note `mysql_real_connect()': mysql-real-connect.
     call.  You can also have the program read option files by calling
     *Note `mysql_options()': mysql-options. See *Note
     c-api-functions::.

   * If you are using the Perl `DBD::mysql' module, you can read
     options from MySQL option files. For example:

          $dsn = "DBI:mysql:test;mysql_read_default_group=client;"
                  . "mysql_read_default_file=/usr/local/mysql/data/my.cnf";
          $dbh = DBI->connect($dsn, $user, $password);

     See *Note perl::.

     Other programming interfaces may provide similar capabilities for
     reading option files.


File: manual.info,  Node: backup-and-recovery,  Next: optimization,  Prev: server-administration,  Up: Top

6 Backup and Recovery
*********************

* Menu:

* backup::                       Database Backups
* backup-strategy-example::      Example Backup and Recovery Strategy
* point-in-time-recovery::       Point-in-Time Recovery
* table-maintenance::            Table Maintenance and Crash Recovery

It is important to back up your databases in case problems occur so
that you can recover your data and be up and running again. MySQL
offers a variety of backup strategies from which you can choose to
select whatever methods best suit the requirements for your
installation.

Briefly summarized, backup concepts with which you should be familiar
include the following:

   * Logical versus physical backups

   * Online versus offline backups

   * Local versus remote backups

   * Snapshot backups

   * Full versus incremental backups

   * Point-in-time recovery

   * Backup scheduling, compression, and encryption

   * Table maintenance

     More generally, the following discussion amplifies on the
     properties of different backup methods.

   * *Logical versus physical (raw) backups.* Logical backups save
     information represented as logical database structure (`CREATE
     DATABASE', `CREATE TABLE' statements) and content (`INSERT'
     statements or delimited-text files). Physical backups consist of
     raw copies of the directories and files that store database
     contents.

     Logical backup methods have these characteristics:

        * The backup is done by going through the MySQL server to
          obtain database structure and content information.

        * Backup is slower than physical methods because the server
          must access database information, convert it to logical
          format, and send it to the backup program.

        * Output is larger than for physical backup, paticularly when
          saved in text format.

        * Backup and restore granularity is available at the server
          level (all databases), database level (all tables in a
          particular database), or table level. This is true regardless
          of storage engine.

        * The backup does not include log or configuration files, or
          other database-related files that are not part of databases.

        * Backups stored in logical format are machine independent and
          highly portable.

        * Logical backups are performed with the MySQL server running
          (the server is not taken offline).

        * Logical backup tools include the `mysqldump' program and the
          `SELECT ... INTO OUTFILE' statement. These work for any
          storage engine, even `MEMORY'.

          For restore, SQL-format dump files can be processed using the
          `mysql' client. To load delimited-text files, use the `LOAD
          DATA INFILE' statement or the `mysqlimport' client.

     Physical backup methods have these characteristics:

        * The backup consists of exact copies of database directories
          and files. Typically this is a copy of all or part of the
          MySQL data directory. Data from `MEMORY' tables cannot be
          backed up this way because their contents are not stored on
          disk.

        * Physical backup methods are faster than logical because they
          involve only file copying without conversion.

        * Output is more compact than for logical backup.

        * Backup and restore granularity extends from the level of the
          entire data directory down to the level of individual files.
          This may or may not provide for table-level granularity,
          depending on storage engine. (Each `MyISAM' table corresponds
          uniquely to a set of files, but an `InnoDB' table shares file
          storage with other `InnoDB' tables.)

        * In addition to databases, the backup can include any related
          files such as log or configuration files.

        * Backups are portable only to other machines that have
          identical or similar hardware characteristics.

        * Backups can be performed while the MySQL server is not
          running. If the server is running, it is necessary to perform
          appropriate locking so that the server does not change
          database contents during the backup.

        * Physical backup tools include filesystem-level commands (such
          as `cp', `scp', `tar', `rsync'), `mysqlhotcopy' for `MyISAM'
          tables, `ibbackup' for `InnoDB' tables, or `START BACKUP' for
          `NDB' tables.

          For restore, files copied at the filesystem level or with
          `mysqlhotcopy' can be copied back to their original locations
          with filesystem commands; `ibback' restores `InnoDB' tables,
          and `ndb_restore' restores `NDB' tables.

   * *Online versus offline backups.* Online backups take place while
     the MySQL server is running so that the database information can
     be obtained from the server.  Offline backups take place while the
     server is stopped. (This distinction can also be described as
     `hot' versus `cold' backups; a `warm' backup is one where the
     server remains running but locked against modifying data while you
     access database files externally.)

     Online backup methods have these characteristics:

        * Less intrusive to other clients, which can connect to the
          MySQL server during the backup and may be able to access data
          depending on what operations they need to perform.

        * Care must be taken to impose appropriate locking so that data
          modifications do not take place that compromise backup
          integrity.

     Offline backup methods have these characteristics:

        * Affects clients adversely because the server is unavailable
          during backup.

        * Simpler backup procedure because there is no possibility of
          interference from client activity.

   * *Local versus remote backups.* A local backup is performed on the
     same host where the MySQL server runs, whereas a remote backup is
     initiated from a different host.

        * `mysqldump' can connect to local or remote servers. For SQL
          output (`CREATE' and `INSERT' statements), local or remote
          dumps can be done and generate output on the client. For
          delimited-text output (with the `--tab' option), data files
          are created on the server host.

        * `mysqlhotcopy' performs only local backups: It connects to
          the server to lock it against data modifications and then
          copies local table files.

        * `SELECT ... INTO OUTFILE' can be initiated from a remote
          client host, but the output file is created on the server
          host.

        * Physical backup methods typically are initiated locally on
          the MySQL server host so that the server can be taken
          offline, although the destination for file copies might be
          remote.

   * *Snapshot backups.* Some filesystem implementations enable
     `snapshots' to be taken. These provide logical copies of the
     filesystem at a given point in time, without having to physically
     copy the entire filesystem. (For example, the implementation may
     use copy-on-write techniques so that only parts of the filesystem
     modified after the snapshot time need be copied.) MySQL itself
     does not provide the capability for taking filesystem snapshots.
     It is available through third-party solutions such as Veritas or
     LVM.

   * *Full versus incremental backups.* A full backup includes all data
     managed by a MySQL server at a given point in time. An incremental
     backup consists of the changes made to the data since the full
     backup.  MySQL has different ways to perform full backups, such as
     those described in previous items. Incremental backups are made
     possible by enabling the server's binary log, which the server
     uses to record data changes.

   * *Point-in-time recovery.* One use for the binary log is to achieve
     point-in-time recovery. This is done by recovering first from the
     backup files to restore the server to its state when the backup
     was made, and then by re-executing changes in subsequently written
     binary log files to redo data modifications up to the desired
     point in time.

   * *Backup scheduling, compression, and encryption.* Backup
     scheduling is valuable for automating backup procedures.
     Compression of backup output reduces space requirements, and
     encryption of the output provides better security against
     unauthorized access of backed-up data. MySQL itself does not
     provide these capabilities. `ibbackup' can compress `InnoDB'
     backups, and compression or encryption of backup output can be
     achieved using filesystem utilities.  Other third-party solutions
     may be available.

   * *Table maintenance.* Data integrity can be compromised if tables
     become corrupt. MySQL provides programs for checking tables and
     repairing them should problems be found. These programs apply
     primarily to `MyISAM' tables. See *Note table-maintenance::.

*Additional resources*

Resources related to backup or to maintaining data availability include
the following:

   * A forum dedicated to backup issues is available at
     `http://forums.mysql.com/list.php?93'.

   * The syntax of the SQL statements described here is given in *Note
     sql-syntax::.

   * Details for `mysqldump', `mysqlhotcopy', and other MySQL backup
     programs can be found in *Note programs::.

   * For additional information about `InnoDB' backup procedures, see
     *Note innodb-backup::.

   * Replication enables you to maintain identical data on multiple
     servers. This has several benefits, such as allowing client load
     to be distributed over servers, availability of data even if a
     given server is taken offline or fails, and the ability to make
     backups using a slave server without affecting the master. See
     *Note replication::.

   * MySQL Cluster provides a high-availability, high-redundancy
     version of MySQL adapted for the distributed computing
     environment. See *Note mysql-cluster::. For information
     specifically about MySQL Cluster backup, see *Note
     mysql-cluster-backup::.

   * Distributed Replicated Block Device (DRBD) is another
     high-availability solution. It works by replicating a block device
     from a primary server to a secondary server at the block level.
     See *Note ha-overview::


File: manual.info,  Node: backup,  Next: backup-strategy-example,  Prev: backup-and-recovery,  Up: backup-and-recovery

6.1 Database Backups
====================

This section summarizes some general methods for making backups.

*Making Backups by Copying Files*

`MyISAM' tables are stored as files, so it is easy to do a backup by
copying files. To get a consistent backup, do a `LOCK TABLES' on the
relevant tables, followed by `FLUSH TABLES' for the tables. See *Note
lock-tables::, and *Note flush::. You need only a read lock; this
allows other clients to continue to query the tables while you are
making a copy of the files in the database directory. The `FLUSH
TABLES' statement is needed to ensure that the all active index pages
are written to disk before you start the backup.

*Making Delimited-Text File Backups*

To create a text file containing a table's data, you can use `SELECT *
INTO OUTFILE 'FILE_NAME' FROM TBL_NAME'. The file is created on the
MySQL server host, not the client host. For this statement, the output
file cannot already exist because allowing files to be overwritten
would constitute a security risk. See *Note select::. This method works
for any kind of data file, but saves only table data, not the table
structure.

To reload the output file, use `LOAD DATA INFILE' or `mysqlimport'.

*Making Backups with `mysqldump' or `mysqlhotcopy'*

Another technique for backing up a database is to use the `mysqldump'
program or the `mysqlhotcopy' script.  `mysqldump' is more general
because it can back up all kinds of tables. `mysqlhotcopy' works only
with some storage engines. (See *Note mysqldump::, and *Note
mysqlhotcopy::.)

Create a full backup of your database:

     shell> mysqldump --tab=/PATH/TO/SOME/DIR --opt DB_NAME

Or:

     shell> mysqlhotcopy DB_NAME /PATH/TO/SOME/DIR

You can also create a binary backup simply by copying all table files
(`*.frm', `*.MYD', and `*.MYI' files), as long as the server isn't
updating anything. The `mysqlhotcopy' script uses this method. (But
note that these methods do not work if your database contains `InnoDB'
tables.  `InnoDB' does not necessarily store table contents in database
directories, and `mysqlhotcopy' works only for `MyISAM' and `ISAM'
tables.)

For `InnoDB' tables, it is possible to perform an online backup that
takes no locks on tables; see *Note mysqldump::.

*Using the Binary Log to Enable Incremental Backups*

MySQL supports incremental backups: You must start the server with the
`--log-bin' option to enable binary logging; see *Note binary-log::.
The binary log files provide you with the information you need to
replicate changes to the database that are made subsequent to the point
at which you performed a backup. At the moment you want to make an
incremental backup (containing all changes that happened since the last
full or incremental backup), you should rotate the binary log by using
`FLUSH LOGS'. This done, you need to copy to the backup location all
binary logs which range from the one of the moment of the last full or
incremental backup to the last but one.  These binary logs are the
incremental backup; at restore time, you apply them as explained in
*Note point-in-time-recovery::. The next time you do a full backup, you
should also rotate the binary log using `FLUSH LOGS', `mysqldump
--flush-logs', or `mysqlhotcopy --flushlog'. See *Note mysqldump::, and
*Note mysqlhotcopy::.

*Backing Up Replication Slaves*

If your MySQL server is a slave replication server, then regardless of
the backup method you choose, you should also back up the `master.info'
and `relay-log.info' files when you back up your slave's data. These
files are always needed to resume replication after you restore the
slave's data. If your slave is subject to replicating `LOAD DATA
INFILE' commands, you should also back up any `SQL_LOAD-*' files that
may exist in the directory specified by the `--slave-load-tmpdir'
option. (This location defaults to the value of the `tmpdir' system
variable if not specified.) The slave needs these files to resume
replication of any interrupted `LOAD DATA INFILE' operations.

MySQL Enterprise

The MySQL Enterprise Monitor provides numerous advisors that issue
immediate warnings should replication issues arise. For more
information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

If you have performance problems with your master server while making
backups, one strategy that can help is to set up replication and
perform backups on the slave rather than on the master. See *Note
replication::.

*Recovering Corrupt Tables*

If you have to restore `MyISAM' tables that have become corrupt, try to
recover them using `REPAIR TABLE' or `myisamchk -r' first. That should
work in 99.9% of all cases. If `myisamchk' fails, try the following
procedure. It is assumed that you have enabled binary logging by
starting MySQL with the `--log-bin' option.

  1. Restore the original `mysqldump' backup, or binary backup.

  2. Execute the following command to re-run the updates in the binary
     logs:

          shell> mysqlbinlog binlog.[0-9]* | mysql

     In some cases, you may want to re-run only certain binary logs,
     from certain positions (usually you want to re-run all binary logs
     from the date of the restored backup, excepting possibly some
     incorrect statements). See *Note point-in-time-recovery::.

*Making Backups Using a Filesystem Snapshot*

If you are using a Veritas filesystem, you can make a backup like this:

  1. From a client program, execute `FLUSH TABLES WITH READ LOCK'.

  2. From another shell, execute `mount vxfs snapshot'.

  3. From the first client, execute `UNLOCK TABLES'.

  4. Copy files from the snapshot.

  5. Unmount the snapshot.


File: manual.info,  Node: backup-strategy-example,  Next: point-in-time-recovery,  Prev: backup,  Up: backup-and-recovery

6.2 Example Backup and Recovery Strategy
========================================

* Menu:

* backup-policy::                Backup Policy
* recovery-from-backups::        Using Backups for Recovery
* backup-strategy-summary::      Backup Strategy Summary

This section discusses a procedure for performing backups that allows
you to recover data after several types of crashes:

   * Operating system crash

   * Power failure

   * Filesystem crash

   * Hardware problem (hard drive, motherboard, and so forth)

The example commands do not include options such as `--user' and
`--password' for the `mysqldump' and `mysql' programs. You should
include such options as necessary so that the MySQL server allows you
to connect to it.

We assume that data is stored in the `InnoDB' storage engine, which has
support for transactions and automatic crash recovery. We also assume
that the MySQL server is under load at the time of the crash. If it
were not, no recovery would ever be needed.

For cases of operating system crashes or power failures, we can assume
that MySQL's disk data is available after a restart. The `InnoDB' data
files might not contain consistent data due to the crash, but `InnoDB'
reads its logs and finds in them the list of pending committed and
non-committed transactions that have not been flushed to the data
files. `InnoDB' automatically rolls back those transactions that were
not committed, and flushes to its data files those that were committed.
Information about this recovery process is conveyed to the user through
the MySQL error log. The following is an example log excerpt:

     InnoDB: Database was not shut down normally.
     InnoDB: Starting recovery from log files...
     InnoDB: Starting log scan based on checkpoint at
     InnoDB: log sequence number 0 13674004
     InnoDB: Doing recovery: scanned up to log sequence number 0 13739520
     InnoDB: Doing recovery: scanned up to log sequence number 0 13805056
     InnoDB: Doing recovery: scanned up to log sequence number 0 13870592
     InnoDB: Doing recovery: scanned up to log sequence number 0 13936128
     ...
     InnoDB: Doing recovery: scanned up to log sequence number 0 20555264
     InnoDB: Doing recovery: scanned up to log sequence number 0 20620800
     InnoDB: Doing recovery: scanned up to log sequence number 0 20664692
     InnoDB: 1 uncommitted transaction(s) which must be rolled back
     InnoDB: Starting rollback of uncommitted transactions
     InnoDB: Rolling back trx no 16745
     InnoDB: Rolling back of trx no 16745 completed
     InnoDB: Rollback of uncommitted transactions completed
     InnoDB: Starting an apply batch of log records to the database...
     InnoDB: Apply batch completed
     InnoDB: Started
     mysqld: ready for connections

For the cases of filesystem crashes or hardware problems, we can assume
that the MySQL disk data is _not_ available after a restart. This means
that MySQL fails to start successfully because some blocks of disk data
are no longer readable. In this case, it is necessary to reformat the
disk, install a new one, or otherwise correct the underlying problem.
Then it is necessary to recover our MySQL data from backups, which
means that we must already have made backups. To make sure that is the
case, we should design a backup policy.


File: manual.info,  Node: backup-policy,  Next: recovery-from-backups,  Prev: backup-strategy-example,  Up: backup-strategy-example

6.2.1 Backup Policy
-------------------

We all know that backups must be scheduled periodically. A full backup
(a snapshot of the data at a point in time) can be done in MySQL with
several tools. For example, `InnoDB Hot Backup' provides online
non-blocking physical backup of the `InnoDB' data files, and
`mysqldump' provides online logical backup.  This discussion uses
`mysqldump'.

MySQL Enterprise

For expert advice on backups and replication, subscribe to the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

Assume that we make a backup on Sunday at 1 p.m., when load is low. The
following command makes a full backup of all our `InnoDB' tables in all
databases:

     shell> mysqldump --single-transaction --all-databases > backup_sunday_1_PM.sql

This is an online, non-blocking backup that does not disturb the reads
and writes on the tables. We assumed earlier that our tables are
`InnoDB' tables, so `--single-transaction' uses a consistent read and
guarantees that data seen by `mysqldump' does not change. (Changes made
by other clients to `InnoDB' tables are not seen by the `mysqldump'
process.) If we do also have other types of tables, we must assume that
they are not changed during the backup. For example, for the `MyISAM'
tables in the `mysql' database, we must assume that no administrative
changes are being made to MySQL accounts during the backup.

The resulting `.sql' file produced by `mysqldump' contains a set of SQL
`INSERT' statements that can be used to reload the dumped tables at a
later time.

Full backups are necessary, but they are not always convenient.  They
produce large backup files and take time to generate. They are not
optimal in the sense that each successive full backup includes all
data, even that part that has not changed since the previous full
backup. After we have made the initial full backup, it is more
efficient to make incremental backups. They are smaller and take less
time to produce. The tradeoff is that, at recovery time, you cannot
restore your data just by reloading the full backup. You must also
process the incremental backups to recover the incremental changes.

To make incremental backups, we need to save the incremental changes.
The MySQL server should always be started with the `--log-bin' option
so that it stores these changes in a file while it updates data. This
option enables binary logging, so that the server writes each SQL
statement that updates data into a file called a MySQL binary log.
Looking at the data directory of a MySQL server that was started with
the `--log-bin' option and that has been running for some days, we find
these MySQL binary log files:

     -rw-rw---- 1 guilhem  guilhem   1277324 Nov 10 23:59 gbichot2-bin.000001
     -rw-rw---- 1 guilhem  guilhem         4 Nov 10 23:59 gbichot2-bin.000002
     -rw-rw---- 1 guilhem  guilhem        79 Nov 11 11:06 gbichot2-bin.000003
     -rw-rw---- 1 guilhem  guilhem       508 Nov 11 11:08 gbichot2-bin.000004
     -rw-rw---- 1 guilhem  guilhem 220047446 Nov 12 16:47 gbichot2-bin.000005
     -rw-rw---- 1 guilhem  guilhem    998412 Nov 14 10:08 gbichot2-bin.000006
     -rw-rw---- 1 guilhem  guilhem       361 Nov 14 10:07 gbichot2-bin.index

Each time it restarts, the MySQL server creates a new binary log file
using the next number in the sequence. While the server is running, you
can also tell it to close the current binary log file and begin a new
one manually by issuing a `FLUSH LOGS' SQL statement or with a
`mysqladmin flush-logs' command. `mysqldump' also has an option to
flush the logs. The `.index' file in the data directory contains the
list of all MySQL binary logs in the directory. This file is used for
replication.

The MySQL binary logs are important for recovery because they form the
set of incremental backups. If you make sure to flush the logs when you
make your full backup, then any binary log files created afterward
contain all the data changes made since the backup. Let's modify the
previous `mysqldump' command a bit so that it flushes the MySQL binary
logs at the moment of the full backup, and so that the dump file
contains the name of the new current binary log:

     shell> mysqldump --single-transaction --flush-logs --master-data=2 \
              --all-databases > backup_sunday_1_PM.sql

After executing this command, the data directory contains a new binary
log file, `gbichot2-bin.000007'. The resulting `.sql' file includes
these lines:

     -- Position to start replication or point-in-time recovery from
     -- CHANGE MASTER TO MASTER_LOG_FILE='gbichot2-bin.000007',MASTER_LOG_POS=4;

Because the `mysqldump' command made a full backup, those lines mean
two things:

   * The `.sql' file contains all changes made before any changes
     written to the `gbichot2-bin.000007' binary log file or newer.

   * All data changes logged after the backup are not present in the
     `.sql', but are present in the `gbichot2-bin.000007' binary log
     file or newer.

On Monday at 1 p.m., we can create an incremental backup by flushing
the logs to begin a new binary log file. For example, executing a
`mysqladmin flush-logs' command creates `gbichot2-bin.000008'. All
changes between the Sunday 1 p.m. full backup and Monday 1 p.m. will be
in the `gbichot2-bin.000007' file. This incremental backup is
important, so it is a good idea to copy it to a safe place. (For
example, back it up on tape or DVD, or copy it to another machine.) On
Tuesday at 1 p.m., execute another `mysqladmin flush-logs' command. All
changes between Monday 1 p.m. and Tuesday 1 p.m. will be in the
`gbichot2-bin.000008' file (which also should be copied somewhere safe).

The MySQL binary logs take up disk space. To free up space, purge them
from time to time. One way to do this is by deleting the binary logs
that are no longer needed, such as when we make a full backup:

     shell> mysqldump --single-transaction --flush-logs --master-data=2 \
              --all-databases --delete-master-logs > backup_sunday_1_PM.sql

*Note*:

Deleting the MySQL binary logs with `mysqldump --delete-master-logs'
can be dangerous if your server is a replication master server, because
slave servers might not yet fully have processed the contents of the
binary log.  The description for the `PURGE MASTER LOGS' statement
explains what should be verified before deleting the MySQL binary logs.
See *Note purge-master-logs::.


File: manual.info,  Node: recovery-from-backups,  Next: backup-strategy-summary,  Prev: backup-policy,  Up: backup-strategy-example

6.2.2 Using Backups for Recovery
--------------------------------

Now, suppose that we have a catastrophic crash on Wednesday at 8 a.m.
that requires recovery from backups. To recover, first we restore the
last full backup we have (the one from Sunday 1 p.m.). The full backup
file is just a set of SQL statements, so restoring it is very easy:

     shell> mysql < backup_sunday_1_PM.sql

At this point, the data is restored to its state as of Sunday 1 p.m..
To restore the changes made since then, we must use the incremental
backups; that is, the `gbichot2-bin.000007' and `gbichot2-bin.000008'
binary log files. Fetch the files if necessary from where they were
backed up, and then process their contents like this:

     shell> mysqlbinlog gbichot2-bin.000007 gbichot2-bin.000008 | mysql

We now have recovered the data to its state as of Tuesday 1 p.m., but
still are missing the changes from that date to the date of the crash.
To not lose them, we would have needed to have the MySQL server store
its MySQL binary logs into a safe location (RAID disks, SAN, ...)
different from the place where it stores its data files, so that these
logs were not on the destroyed disk. (That is, we can start the server
with a `--log-bin' option that specifies a location on a different
physical device from the one on which the data directory resides. That
way, the logs are safe even if the device containing the directory is
lost.) If we had done this, we would have the `gbichot2-bin.000009' file
at hand, and we could apply it using `mysqlbinlog' and `mysql' to
restore the most recent data changes with no loss up to the moment of
the crash.


File: manual.info,  Node: backup-strategy-summary,  Prev: recovery-from-backups,  Up: backup-strategy-example

6.2.3 Backup Strategy Summary
-----------------------------

In case of an operating system crash or power failure, `InnoDB' itself
does all the job of recovering data. But to make sure that you can
sleep well, observe the following guidelines:

   * Always run the MySQL server with the `--log-bin' option, or even
     `--log-bin=LOG_NAME', where the log file name is located on some
     safe media different from the drive on which the data directory is
     located. If you have such safe media, this technique can also be
     good for disk load balancing (which results in a performance
     improvement).

   * Make periodic full backups, using the `mysqldump' command shown
     earlier in *Note backup-policy::, that makes an online,
     non-blocking backup.

   * Make periodic incremental backups by flushing the logs with `FLUSH
     LOGS' or `mysqladmin flush-logs'.


File: manual.info,  Node: point-in-time-recovery,  Next: table-maintenance,  Prev: backup-strategy-example,  Up: backup-and-recovery

6.3 Point-in-Time Recovery
==========================

* Menu:

* point-in-time-recovery-times::  Specifying Times for Recovery
* point-in-time-recovery-positions::  Specifying Positions for Recovery

If a MySQL server was started with the `--log-bin' option to enable
binary logging, you can use the `mysqlbinlog' utility to recover data
from the binary log files, starting from a specified point in time (for
example, since your last backup) until the present or another specified
point in time. For information on enabling the binary log and using
`mysqlbinlog', see *Note binary-log::, and *Note mysqlbinlog::.

MySQL Enterprise

For maximum data recovery, the MySQL Enterprise Monitor advises
subscribers to synchronize to disk at each write. For more information,
see `http://www.mysql.com/products/enterprise/advisors.html'.

To restore data from a binary log, you must know the location and name
of the current binary log file. By default, the server creates binary
log files in the data directory, but a pathname can be specified with
the `--log-bin' option to place the files in a different location.
Typically the option is given in an option file (that is, `my.cnf' or
`my.ini', depending on your system). It can also be given on the
command line when the server is started. To determine the name of the
current binary log file, issue the following statement:

     mysql> SHOW MASTER STATUS

If you prefer, you can execute the following command from the command
line instead:

     shell> mysql -u root -p -E -e "SHOW MASTER STATUS"

Enter the `root' password for your server when `mysql' prompts you for
it.

To view the contents of a binary log, use `mysqlbinlog'. See *Note
mysqlbinlog::.


File: manual.info,  Node: point-in-time-recovery-times,  Next: point-in-time-recovery-positions,  Prev: point-in-time-recovery,  Up: point-in-time-recovery

6.3.1 Specifying Times for Recovery
-----------------------------------

To indicate the start and end times for recovery, specify the
`--start-date' and `--stop-date' options for `mysqlbinlog', in
`DATETIME' format. As an example, suppose that exactly at 10:00 a.m. on
April 20, 2005 an SQL statement was executed that deleted a large
table. To restore the table and data, you could restore the previous
night's backup, and then execute the following command:

     shell> mysqlbinlog --stop-date="2005-04-20 9:59:59" \
              /var/log/mysql/bin.123456 | mysql -u root -p

This command recovers all of the data up until the date and time given
by the `--stop-date' option. If you did not detect the erroneous SQL
statement that was entered until hours later, you will probably also
want to recover the activity that occurred afterward. Based on this,
you could run `mysqlbinlog' again with a start date and time, like so:

     shell> mysqlbinlog --start-date="2005-04-20 10:01:00" \
              /var/log/mysql/bin.123456 | mysql -u root -p

In this command, the SQL statements logged from 10:01 a.m. on will be
re-executed. The combination of restoring of the previous night's dump
file and the two `mysqlbinlog' commands restores everything up until
one second before 10:00 a.m. and everything from 10:01 a.m. on. You
should examine the log to be sure of the exact times to specify for the
commands. To display the log file contents without executing them, use
this command:

     shell> mysqlbinlog /var/log/mysql/bin.123456 > /tmp/mysql_restore.sql

Then open the file with a text editor to examine it.


File: manual.info,  Node: point-in-time-recovery-positions,  Prev: point-in-time-recovery-times,  Up: point-in-time-recovery

6.3.2 Specifying Positions for Recovery
---------------------------------------

Instead of specifying dates and times, the `--start-position' and
`--stop-position' options for `mysqlbinlog' can be used for specifying
log positions. They work the same as the start and stop date options,
except that you specify log position numbers rather than dates. Using
positions may enable you to be more precise about which part of the log
to recover, especially if many transactions occurred around the same
time as a damaging SQL statement. To determine the position numbers, run
`mysqlbinlog' for a range of times near the time when the unwanted
transaction was executed, but redirect the results to a text file for
examination. This can be done like so:

     shell> mysqlbinlog --start-date="2005-04-20 9:55:00" \
              --stop-date="2005-04-20 10:05:00" \
              /var/log/mysql/bin.123456 > /tmp/mysql_restore.sql

This command creates a small text file in the `/tmp' directory that
contains the SQL statements around the time that the deleterious SQL
statement was executed. Open this file with a text editor and look for
the statement that you don't want to repeat. Determine the positions in
the binary log for stopping and resuming the recovery and make note of
them. Positions are labeled as `log_pos' followed by a number. After
restoring the previous backup file, use the position numbers to process
the binary log file. For example, you would use commands something like
these:

     shell> mysqlbinlog --stop-position="368312" /var/log/mysql/bin.123456 \
              | mysql -u root -p

     shell> mysqlbinlog --start-position="368315" /var/log/mysql/bin.123456 \
              | mysql -u root -p

The first command recovers all the transactions up until the stop
position given. The second command recovers all transactions from the
starting position given until the end of the binary log. Because the
output of `mysqlbinlog' includes `SET TIMESTAMP' statements before each
SQL statement recorded, the recovered data and related MySQL logs will
reflect the original times at which the transactions were executed.


File: manual.info,  Node: table-maintenance,  Prev: point-in-time-recovery,  Up: backup-and-recovery

6.4 Table Maintenance and Crash Recovery
========================================

* Menu:

* crash-recovery::               Using `myisamchk' for Crash Recovery
* check::                        How to Check `MyISAM' Tables for Errors
* repair::                       How to Repair Tables
* table-optimization::           Table Optimization
* table-info::                   Getting Information About a Table
* maintenance-schedule::         Setting Up a Table Maintenance Schedule

This section discusses how to use `myisamchk' to check or repair
`MyISAM' tables (tables that have `.MYD' and `.MYI' files for storing
data and indexes). For general `myisamchk' background, see *Note
myisamchk::.

You can use `myisamchk' to get information about your database tables
or to check, repair, or optimize them. The following sections describe
how to perform these operations and how to set up a table maintenance
schedule.

Even though table repair with `myisamchk' is quite secure, it is always
a good idea to make a backup _before_ doing a repair or any maintenance
operation that could make a lot of changes to a table.

`myisamchk' operations that affect indexes can cause `FULLTEXT' indexes
to be rebuilt with full-text parameters that are incompatible with the
values used by the MySQL server. To avoid this problem, follow the
guidelines in *Note myisamchk-general-options::.

In many cases, you may find it simpler to do `MyISAM' table maintenance
using the SQL statements that perform operations that `myisamchk' can
do:

   * To check or repair `MyISAM' tables, use `CHECK TABLE' or `REPAIR
     TABLE'.

   * To optimize `MyISAM' tables, use `OPTIMIZE TABLE'.

   * To analyze `MyISAM' tables, use `ANALYZE TABLE'.

These statements can be used directly or by means of the `mysqlcheck'
client program. One advantage of these statements over `myisamchk' is
that the server does all the work. With `myisamchk', you must make sure
that the server does not use the tables at the same time so that there
is no unwanted interaction between `myisamchk' and the server. See
*Note analyze-table::, *Note check-table::, *Note optimize-table::, and
*Note repair-table::.


File: manual.info,  Node: crash-recovery,  Next: check,  Prev: table-maintenance,  Up: table-maintenance

6.4.1 Using `myisamchk' for Crash Recovery
------------------------------------------

This section describes how to check for and deal with data corruption
in MySQL databases. If your tables become corrupted frequently, you
should try to find the reason why. See *Note crashing::.

For an explanation of how `MyISAM' tables can become corrupted, see
*Note myisam-table-problems::.

If you run `mysqld' with external locking disabled (which is the
default as of MySQL 4.0), you cannot reliably use `myisamchk' to check
a table when `mysqld' is using the same table. If you can be certain
that no one will access the tables through `mysqld' while you run
`myisamchk', you only have to execute `mysqladmin flush-tables' before
you start checking the tables. If you cannot guarantee this, you must
stop `mysqld' while you check the tables. If you run `myisamchk' to
check tables that `mysqld' is updating at the same time, you may get a
warning that a table is corrupt even when it is not.

If the server is run with external locking enabled, you can use
`myisamchk' to check tables at any time. In this case, if the server
tries to update a table that `myisamchk' is using, the server will wait
for `myisamchk' to finish before it continues.

If you use `myisamchk' to repair or optimize tables, you _must_ always
ensure that the `mysqld' server is not using the table (this also
applies if external locking is disabled). If you don't stop `mysqld',
you should at least do a `mysqladmin flush-tables' before you run
`myisamchk'. Your tables _may become corrupted_ if the server and
`myisamchk' access the tables simultaneously.

When performing crash recovery, it is important to understand that each
`MyISAM' table TBL_NAME in a database corresponds to three files in the
database directory:

*File*         *Purpose*
`TBL_NAME.frm' Definition (format) file
`TBL_NAME.MYD' Data file
`TBL_NAME.MYI' Index file

Each of these three file types is subject to corruption in various
ways, but problems occur most often in data files and index files.

`myisamchk' works by creating a copy of the `.MYD' data file row by
row. It ends the repair stage by removing the old `.MYD' file and
renaming the new file to the original file name. If you use `--quick',
`myisamchk' does not create a temporary `.MYD' file, but instead
assumes that the `.MYD' file is correct and generates only a new index
file without touching the `.MYD' file. This is safe, because
`myisamchk' automatically detects whether the `.MYD' file is corrupt
and aborts the repair if it is. You can also specify the `--quick'
option twice to `myisamchk'. In this case, `myisamchk' does not abort
on some errors (such as duplicate-key errors) but instead tries to
resolve them by modifying the `.MYD' file. Normally the use of two
`--quick' options is useful only if you have too little free disk space
to perform a normal repair. In this case, you should at least make a
backup of the table before running `myisamchk'.


File: manual.info,  Node: check,  Next: repair,  Prev: crash-recovery,  Up: table-maintenance

6.4.2 How to Check `MyISAM' Tables for Errors
---------------------------------------------

To check a `MyISAM' table, use the following commands:

   * `myisamchk TBL_NAME'

     This finds 99.99% of all errors. What it cannot find is corruption
     that involves _only_ the data file (which is very unusual). If you
     want to check a table, you should normally run `myisamchk' without
     options or with the `-s' (silent) option.

   * `myisamchk -m TBL_NAME'

     This finds 99.999% of all errors. It first checks all index
     entries for errors and then reads through all rows. It calculates
     a checksum for all key values in the rows and verifies that the
     checksum matches the checksum for the keys in the index tree.

   * `myisamchk -e TBL_NAME'

     This does a complete and thorough check of all data (`-e' means
     `extended check').  It does a check-read of every key for each row
     to verify that they indeed point to the correct row. This may take
     a long time for a large table that has many indexes. Normally,
     `myisamchk' stops after the first error it finds. If you want to
     obtain more information, you can add the `-v' (verbose) option.
     This causes `myisamchk' to keep going, up through a maximum of 20
     errors.

   * `myisamchk -e -i TBL_NAME'

     This is like the previous command, but the `-i' option tells
     `myisamchk' to print additional statistical information.

In most cases, a simple `myisamchk' command with no arguments other
than the table name is sufficient to check a table.


File: manual.info,  Node: repair,  Next: table-optimization,  Prev: check,  Up: table-maintenance

6.4.3 How to Repair Tables
--------------------------

The discussion in this section describes how to use `myisamchk' on
`MyISAM' tables (extensions `.MYI' and `.MYD').

You can also (and should, if possible) use the `CHECK TABLE' and
`REPAIR TABLE' statements to check and repair `MyISAM' tables. See
*Note check-table::, and *Note repair-table::.

Symptoms of corrupted tables include queries that abort unexpectedly
and observable errors such as these:

   * `TBL_NAME.frm' is locked against change

   * Can't find file `TBL_NAME.MYI' (Errcode: NNN)

   * Unexpected end of file

   * Record file is crashed

   * Got error NNN from table handler

To get more information about the error, run `perror' NNN, where NNN is
the error number. The following example shows how to use `perror' to
find the meanings for the most common error numbers that indicate a
problem with a table:

     shell> perror 126 127 132 134 135 136 141 144 145
     MySQL error code 126 = Index file is crashed
     MySQL error code 127 = Record-file is crashed
     MySQL error code 132 = Old database file
     MySQL error code 134 = Record was already deleted (or record file crashed)
     MySQL error code 135 = No more room in record file
     MySQL error code 136 = No more room in index file
     MySQL error code 141 = Duplicate unique key or constraint on write or update
     MySQL error code 144 = Table is crashed and last repair failed
     MySQL error code 145 = Table was marked as crashed and should be repaired

Note that error 135 (no more room in record file) and error 136 (no
more room in index file) are not errors that can be fixed by a simple
repair. In this case, you must use `ALTER TABLE' to increase the
`MAX_ROWS' and `AVG_ROW_LENGTH' table option values:

     ALTER TABLE TBL_NAME MAX_ROWS=XXX AVG_ROW_LENGTH=YYY;

If you do not know the current table option values, use `SHOW CREATE
TABLE'.

For the other errors, you must repair your tables.  `myisamchk' can
usually detect and fix most problems that occur.

The repair process involves up to four stages, described here.  Before
you begin, you should change location to the database directory and
check the permissions of the table files. On Unix, make sure that they
are readable by the user that `mysqld' runs as (and to you, because you
need to access the files you are checking). If it turns out you need to
modify files, they must also be writable by you.

This section is for the cases where a table check fails (such as those
described in *Note check::), or you want to use the extended features
that `myisamchk' provides.

The options that you can use for table maintenance with `myisamchk' are
described in *Note myisamchk::.

If you are going to repair a table from the command line, you must
first stop the `mysqld' server. Note that when you do `mysqladmin
shutdown' on a remote server, the `mysqld' server is still alive for a
while after `mysqladmin' returns, until all statement-processing has
stopped and all index changes have been flushed to disk.

*Stage 1: Checking your tables*

Run `myisamchk *.MYI' or `myisamchk -e *.MYI' if you have more time.
Use the `-s' (silent) option to suppress unnecessary information.

If the `mysqld' server is stopped, you should use the `--update-state'
option to tell `myisamchk' to mark the table as `checked.'

You have to repair only those tables for which `myisamchk' announces an
error. For such tables, proceed to Stage 2.

If you get unexpected errors when checking (such as `out of memory'
errors), or if `myisamchk' crashes, go to Stage 3.

*Stage 2: Easy safe repair*

First, try `myisamchk -r -q TBL_NAME' (`-r -q' means `quick recovery
mode'). This attempts to repair the index file without touching the data
file. If the data file contains everything that it should and the
delete links point at the correct locations within the data file, this
should work, and the table is fixed. Start repairing the next table.
Otherwise, use the following procedure:

  1. Make a backup of the data file before continuing.

  2. Use `myisamchk -r TBL_NAME' (`-r' means `recovery mode').  This
     removes incorrect rows and deleted rows from the data file and
     reconstructs the index file.

  3. If the preceding step fails, use `myisamchk --safe-recover
     TBL_NAME'. Safe recovery mode uses an old recovery method that
     handles a few cases that regular recovery mode does not (but is
     slower).

*Note*:

If you want a repair operation to go much faster, you should set the
values of the `sort_buffer_size' and `key_buffer_size' variables each
to about 25% of your available memory when running `myisamchk'.

If you get unexpected errors when repairing (such as `out of memory'
errors), or if `myisamchk' crashes, go to Stage 3.

*Stage 3: Difficult repair*

You should reach this stage only if the first 16KB block in the index
file is destroyed or contains incorrect information, or if the index
file is missing. In this case, it is necessary to create a new index
file. Do so as follows:

  1. Move the data file to a safe place.

  2. Use the table description file to create new (empty) data and
     index files:

          shell> mysql DB_NAME
          mysql> SET AUTOCOMMIT=1;
          mysql> TRUNCATE TABLE TBL_NAME;
          mysql> quit

  3. Copy the old data file back onto the newly created data file. (Do
     not just move the old file back onto the new file.  You want to
     retain a copy in case something goes wrong.)

*Important*:

If you are using replication, you should stop it prior to performing
the above procedure, since it involves filesystem operations, and these
are not logged by MySQL.

Go back to Stage 2. `myisamchk -r -q' should work. (This should not be
an endless loop.)

You can also use the `REPAIR TABLE TBL_NAME USE_FRM' SQL statement,
which performs the whole procedure automatically.  There is also no
possibility of unwanted interaction between a utility and the server,
because the server does all the work when you use `REPAIR TABLE'. See
*Note repair-table::.

*Stage 4: Very difficult repair*

You should reach this stage only if the `.frm' description file has
also crashed.  That should never happen, because the description file
is not changed after the table is created:

  1. Restore the description file from a backup and go back to Stage 3.
     You can also restore the index file and go back to Stage 2. In the
     latter case, you should start with `myisamchk -r'.

  2. If you do not have a backup but know exactly how the table was
     created, create a copy of the table in another database.  Remove
     the new data file, and then move the `.frm' description and `.MYI'
     index files from the other database to your crashed database. This
     gives you new description and index files, but leaves the `.MYD'
     data file alone. Go back to Stage 2 and attempt to reconstruct the
     index file.


File: manual.info,  Node: table-optimization,  Next: table-info,  Prev: repair,  Up: table-maintenance

6.4.4 Table Optimization
------------------------

To coalesce fragmented rows and eliminate wasted space that results
from deleting or updating rows, run `myisamchk' in recovery mode:

     shell> myisamchk -r TBL_NAME

You can optimize a table in the same way by using the `OPTIMIZE TABLE'
SQL statement.  `OPTIMIZE TABLE' does a table repair and a key
analysis, and also sorts the index tree so that key lookups are faster.
There is also no possibility of unwanted interaction between a utility
and the server, because the server does all the work when you use
`OPTIMIZE TABLE'. See *Note optimize-table::.

`myisamchk' has a number of other options that you can use to improve
the performance of a table:

   * `--analyze', `-a'

   * `--sort-index', `-S'

   * `--sort-records=INDEX_NUM', `-R INDEX_NUM'

For a full description of all available options, see *Note myisamchk::.


File: manual.info,  Node: table-info,  Next: maintenance-schedule,  Prev: table-optimization,  Up: table-maintenance

6.4.5 Getting Information About a Table
---------------------------------------

To obtain a description of a table or statistics about it, use the
commands shown here. We explain some of the information in more detail
later.

   * `myisamchk -d TBL_NAME'

     Runs `myisamchk' in `describe mode' to produce a description of
     your table. If you start the MySQL server with external locking
     disabled, `myisamchk' may report an error for a table that is
     updated while it runs. However, because `myisamchk' does not
     change the table in describe mode, there is no risk of destroying
     data.

   * `myisamchk -d -v TBL_NAME'

     Adding `-v' runs `myisamchk' in verbose mode so that it produces
     more information about what it is doing.

   * `myisamchk -eis TBL_NAME'

     Shows only the most important information from a table. This
     operation is slow because it must read the entire table.

   * `myisamchk -eiv TBL_NAME'

     This is like `-eis', but tells you what is being done.

The TBL_NAME argument can be either the name of a `MyISAM' table or the
name of its index file, as described in *Note myisamchk::.  Multiple
TBL_NAME arguments can be given.

Sample output for some of these commands follows. They are based on a
table with these data and index file sizes:

     -rw-rw-r--   1 monty    tcx     317235748 Jan 12 17:30 company.MYD
     -rw-rw-r--   1 davida   tcx      96482304 Jan 12 18:35 company.MYI

Example of `myisamchk -d' output:

     MyISAM file:     company.MYI
     Record format:   Fixed length
     Data records:    1403698  Deleted blocks:         0
     Recordlength:    226

     table description:
     Key Start Len Index   Type
     1   2     8   unique  double
     2   15    10  multip. text packed stripped
     3   219   8   multip. double
     4   63    10  multip. text packed stripped
     5   167   2   multip. unsigned short
     6   177   4   multip. unsigned long
     7   155   4   multip. text
     8   138   4   multip. unsigned long
     9   177   4   multip. unsigned long
         193   1           text

Example of `myisamchk -d -v' output:

     MyISAM file:         company
     Record format:       Fixed length
     File-version:        1
     Creation time:       1999-10-30 12:12:51
     Recover time:        1999-10-31 19:13:01
     Status:              checked
     Data records:            1403698  Deleted blocks:              0
     Datafile parts:          1403698  Deleted data:                0
     Datafile pointer (bytes):      3  Keyfile pointer (bytes):     3
     Max datafile length:  3791650815  Max keyfile length: 4294967294
     Recordlength:                226

     table description:
     Key Start Len Index   Type                  Rec/key     Root Blocksize
     1   2     8   unique  double                      1 15845376      1024
     2   15    10  multip. text packed stripped        2 25062400      1024
     3   219   8   multip. double                     73 40907776      1024
     4   63    10  multip. text packed stripped        5 48097280      1024
     5   167   2   multip. unsigned short           4840 55200768      1024
     6   177   4   multip. unsigned long            1346 65145856      1024
     7   155   4   multip. text                     4995 75090944      1024
     8   138   4   multip. unsigned long              87 85036032      1024
     9   177   4   multip. unsigned long             178 96481280      1024
         193   1           text

Example of `myisamchk -eis' output:

     Checking MyISAM file: company
     Key:  1:  Keyblocks used:  97%  Packed:    0%  Max levels:  4
     Key:  2:  Keyblocks used:  98%  Packed:   50%  Max levels:  4
     Key:  3:  Keyblocks used:  97%  Packed:    0%  Max levels:  4
     Key:  4:  Keyblocks used:  99%  Packed:   60%  Max levels:  3
     Key:  5:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     Key:  6:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     Key:  7:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     Key:  8:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     Key:  9:  Keyblocks used:  98%  Packed:    0%  Max levels:  4
     Total:    Keyblocks used:  98%  Packed:   17%

     Records:          1403698    M.recordlength:     226
     Packed:             0%
     Recordspace used:     100%   Empty space:          0%
     Blocks/Record:   1.00
     Record blocks:    1403698    Delete blocks:        0
     Recorddata:     317235748    Deleted data:         0
     Lost space:             0    Linkdata:             0

     User time 1626.51, System time 232.36
     Maximum resident set size 0, Integral resident set size 0
     Non physical pagefaults 0, Physical pagefaults 627, Swaps 0
     Blocks in 0 out 0, Messages in 0 out 0, Signals 0
     Voluntary context switches 639, Involuntary context switches 28966

Example of `myisamchk -eiv' output:

     Checking MyISAM file: company
     Data records: 1403698   Deleted blocks:       0
     - check file-size
     - check delete-chain
     block_size 1024:
     index  1:
     index  2:
     index  3:
     index  4:
     index  5:
     index  6:
     index  7:
     index  8:
     index  9:
     No recordlinks
     - check index reference
     - check data record references index: 1
     Key:  1:  Keyblocks used:  97%  Packed:    0%  Max levels:  4
     - check data record references index: 2
     Key:  2:  Keyblocks used:  98%  Packed:   50%  Max levels:  4
     - check data record references index: 3
     Key:  3:  Keyblocks used:  97%  Packed:    0%  Max levels:  4
     - check data record references index: 4
     Key:  4:  Keyblocks used:  99%  Packed:   60%  Max levels:  3
     - check data record references index: 5
     Key:  5:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     - check data record references index: 6
     Key:  6:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     - check data record references index: 7
     Key:  7:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     - check data record references index: 8
     Key:  8:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     - check data record references index: 9
     Key:  9:  Keyblocks used:  98%  Packed:    0%  Max levels:  4
     Total:    Keyblocks used:   9%  Packed:   17%

     - check records and index references
     *** LOTS OF ROW NUMBERS DELETED ***

     Records:         1403698   M.recordlength:   226   Packed:           0%
     Recordspace used:    100%  Empty space:        0%  Blocks/Record: 1.00
     Record blocks:   1403698   Delete blocks:      0
     Recorddata:    317235748   Deleted data:       0
     Lost space:            0   Linkdata:           0

     User time 1639.63, System time 251.61
     Maximum resident set size 0, Integral resident set size 0
     Non physical pagefaults 0, Physical pagefaults 10580, Swaps 0
     Blocks in 4 out 0, Messages in 0 out 0, Signals 0
     Voluntary context switches 10604, Involuntary context switches 122798

Explanations for the types of information `myisamchk' produces are
given here.  `Keyfile' refers to the index file.  `Record' and `row'
are synonymous.

   * `MyISAM file'

     Name of the `MyISAM' (index) file.

   * `File-version'

     Version of `MyISAM' format. Currently always 2.

   * `Creation time'

     When the data file was created.

   * `Recover time'

     When the index/data file was last reconstructed.

   * `Data records'

     How many rows are in the table.

   * `Deleted blocks'

     How many deleted blocks still have reserved space. You can
     optimize your table to minimize this space. See *Note
     table-optimization::.

   * `Datafile parts'

     For dynamic-row format, this indicates how many data blocks there
     are. For an optimized table without fragmented rows, this is the
     same as `Data records'.

   * `Deleted data'

     How many bytes of unreclaimed deleted data there are. You can
     optimize your table to minimize this space. See *Note
     table-optimization::.

   * `Datafile pointer'

     The size of the data file pointer, in bytes. It is usually 2, 3,
     4, or 5 bytes. Most tables manage with 2 bytes, but this cannot be
     controlled from MySQL yet. For fixed tables, this is a row
     address. For dynamic tables, this is a byte address.

   * `Keyfile pointer'

     The size of the index file pointer, in bytes. It is usually 1, 2,
     or 3 bytes. Most tables manage with 2 bytes, but this is
     calculated automatically by MySQL. It is always a block address.

   * `Max datafile length'

     How long the table data file can become, in bytes.

   * `Max keyfile length'

     How long the table index file can become, in bytes.

   * `Recordlength'

     How much space each row takes, in bytes.

   * `Record format'

     The format used to store table rows. The preceding examples use
     `Fixed length'. Other possible values are `Compressed' and
     `Packed'.

   * `table description'

     A list of all keys in the table. For each key, `myisamchk'
     displays some low-level information:

        * `Key'

          This key's number.

        * `Start'

          Where in the row this portion of the index starts.

        * `Len'

          How long this portion of the index is. For packed numbers,
          this should always be the full length of the column. For
          strings, it may be shorter than the full length of the
          indexed column, because you can index a prefix of a string
          column.

        * `Index'

          Whether a key value can exist multiple times in the index.
          Possible values are `unique' or `multip.' (multiple).

        * `Type'

          What data type this portion of the index has. This is a
          `MyISAM' data type with the possible values `packed',
          `stripped', or `empty'.

        * `Root'

          Address of the root index block.

        * `Blocksize'

          The size of each index block. By default this is 1024, but
          the value may be changed at compile time when MySQL is built
          from source.

        * `Rec/key'

          This is a statistical value used by the optimizer. It tells
          how many rows there are per value for this index.  A unique
          index always has a value of 1. This may be updated after a
          table is loaded (or greatly changed) with `myisamchk -a'. If
          this is not updated at all, a default value of 30 is given.

     For the table shown in the examples, there are two `table
     description' lines for the ninth index. This indicates that it is
     a multiple-part index with two parts.

   * `Keyblocks used'

     What percentage of the keyblocks are used. When a table has just
     been reorganized with `myisamchk', as for the table in the
     examples, the values are very high (very near the theoretical
     maximum).

   * `Packed'

     MySQL tries to pack key values that have a common suffix.  This
     can only be used for indexes on `CHAR' and `VARCHAR' columns. For
     long indexed strings that have similar leftmost parts, this can
     significantly reduce the space used. In the third of the preceding
     examples, the fourth key is 10 characters long and a 60% reduction
     in space is achieved.

   * `Max levels'

     How deep the B-tree for this key is. Large tables with long key
     values get high values.

   * `Records'

     How many rows are in the table.

   * `M.recordlength'

     The average row length. This is the exact row length for tables
     with fixed-length rows, because all rows have the same length.

   * `Packed'

     MySQL strips spaces from the end of strings. The `Packed' value
     indicates the percentage of savings achieved by doing this.

   * `Recordspace used'

     What percentage of the data file is used.

   * `Empty space'

     What percentage of the data file is unused.

   * `Blocks/Record'

     Average number of blocks per row (that is, how many links a
     fragmented row is composed of). This is always 1.0 for
     fixed-format tables. This value should stay as close to 1.0 as
     possible. If it gets too large, you can reorganize the table. See
     *Note table-optimization::.

   * `Recordblocks'

     How many blocks (links) are used. For fixed-format tables, this is
     the same as the number of rows.

   * `Deleteblocks'

     How many blocks (links) are deleted.

   * `Recorddata'

     How many bytes in the data file are used.

   * `Deleted data'

     How many bytes in the data file are deleted (unused).

   * `Lost space'

     If a row is updated to a shorter length, some space is lost.  This
     is the sum of all such losses, in bytes.

   * `Linkdata'

     When the dynamic table format is used, row fragments are linked
     with pointers (4 to 7 bytes each).  `Linkdata' is the sum of the
     amount of storage used by all such pointers.

If a table has been compressed with `myisampack', `myisamchk -d' prints
additional information about each table column. See *Note myisampack::,
for an example of this information and a description of what it means.


File: manual.info,  Node: maintenance-schedule,  Prev: table-info,  Up: table-maintenance

6.4.6 Setting Up a Table Maintenance Schedule
---------------------------------------------

It is a good idea to perform table checks on a regular basis rather
than waiting for problems to occur. One way to check and repair
`MyISAM' tables is with the `CHECK TABLE' and `REPAIR TABLE'
statements. See *Note check-table::, and *Note repair-table::.

Another way to check tables is to use `myisamchk'. For maintenance
purposes, you can use `myisamchk -s'. The `-s' option (short for
`--silent') causes `myisamchk' to run in silent mode, printing messages
only when errors occur.

It is also a good idea to enable automatic `MyISAM' table checking. For
example, whenever the machine has done a restart in the middle of an
update, you usually need to check each table that could have been
affected before it is used further. (These are `expected crashed
tables.') To check `MyISAM' tables automatically, start the server with
the `--myisam-recover' option. See *Note server-options::.

You should also check your tables regularly during normal system
operation. At MySQL AB, we run a `cron' job to check all our important
tables once a week, using a line like this in a `crontab' file:

     35 0 * * 0 /PATH/TO/MYISAMCHK --fast --silent /PATH/TO/DATADIR/*/*.MYI

This prints out information about crashed tables so that we can examine
and repair them when needed.

Because we have not had any unexpectedly crashed tables (tables that
become corrupted for reasons other than hardware trouble) for several
years, once a week is more than sufficient for us.

We recommend that to start with, you execute `myisamchk -s' each night
on all tables that have been updated during the last 24 hours, until
you come to trust MySQL as much as we do.

Normally, MySQL tables need little maintenance. If you are performing
many updates to `MyISAM' tables with dynamic-sized rows (tables with
`VARCHAR', `BLOB', or `TEXT' columns) or have tables with many deleted
rows you may want to defragment/reclaim space from the tables from time
to time. You can do this by using `OPTIMIZE TABLE' on the tables in
question. Alternatively, if you can stop the `mysqld' server for a
while, change location into the data directory and use this command
while the server is stopped:

     shell> myisamchk -r -s --sort-index --sort_buffer_size=16M */*.MYI


File: manual.info,  Node: optimization,  Next: language-structure,  Prev: backup-and-recovery,  Up: Top

7 Optimization
**************

* Menu:

* optimize-overview::            Optimization Overview
* query-speed::                  Optimizing `SELECT' and Other Statements
* locking-issues::               Locking Issues
* optimizing-database-structure::  Optimizing Database Structure
* optimizing-the-server::        Optimizing the MySQL Server
* disk-issues::                  Disk Issues

Optimization is a complex task because ultimately it requires
understanding of the entire system to be optimized. Although it may be
possible to perform some local optimizations with little knowledge of
your system or application, the more optimal you want your system to
become, the more you must know about it.

This chapter tries to explain and give some examples of different ways
to optimize MySQL. Remember, however, that there are always additional
ways to make the system even faster, although they may require
increasing effort to achieve.


File: manual.info,  Node: optimize-overview,  Next: query-speed,  Prev: optimization,  Up: optimization

7.1 Optimization Overview
=========================

* Menu:

* design-limitations::           MySQL Design Limitations and Tradeoffs
* portability::                  Designing Applications for Portability
* internal-use::                 What We Have Used MySQL For
* mysql-benchmarks::             The MySQL Benchmark Suite
* custom-benchmarks::            Using Your Own Benchmarks

The most important factor in making a system fast is its basic design.
You must also know what kinds of processing your system is doing, and
what its bottlenecks are. In most cases, system bottlenecks arise from
these sources:

   * Disk seeks. It takes time for the disk to find a piece of data.
     With modern disks, the mean time for this is usually lower than
     10ms, so we can in theory do about 100 seeks a second. This time
     improves slowly with new disks and is very hard to optimize for a
     single table. The way to optimize seek time is to distribute the
     data onto more than one disk.

   * Disk reading and writing. When the disk is at the correct
     position, we need to read the data. With modern disks, one disk
     delivers at least 10-20MB/s throughput. This is easier to optimize
     than seeks because you can read in parallel from multiple disks.

   * CPU cycles. When we have the data in main memory, we need to
     process it to get our result. Having small tables compared to the
     amount of memory is the most common limiting factor. But with
     small tables, speed is usually not the problem.

   * Memory bandwidth. When the CPU needs more data than can fit in the
     CPU cache, main memory bandwidth becomes a bottleneck.  This is an
     uncommon bottleneck for most systems, but one to be aware of.

MySQL Enterprise

For instant notification of system bottlenecks subscribe to the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: design-limitations,  Next: portability,  Prev: optimize-overview,  Up: optimize-overview

7.1.1 MySQL Design Limitations and Tradeoffs
--------------------------------------------

When using the `MyISAM' storage engine, MySQL uses extremely fast table
locking that allows multiple readers or a single writer. The biggest
problem with this storage engine occurs when you have a steady stream
of mixed updates and slow selects on a single table. If this is a
problem for certain tables, you can use another storage engine for
them. See *Note storage-engines::.

MySQL can work with both transactional and non-transactional tables. To
make it easier to work smoothly with non-transactional tables (which
cannot roll back if something goes wrong), MySQL has the following
rules. Note that these rules apply _only_ when not running in strict
SQL mode or if you use the `IGNORE' specifier for `INSERT' or `UPDATE'.

   * All columns have default values.

   * If you insert an inappropriate or out-of-range value into a
     column, MySQL sets the column to the `best possible value' instead
     of reporting an error. For numerical values, this is 0, the
     smallest possible value or the largest possible value. For
     strings, this is either the empty string or as much of the string
     as can be stored in the column.

   * All calculated expressions return a value that can be used instead
     of signaling an error condition. For example, 1/0 returns `NULL'.

To change the preceding behaviors, you can enable stricter data
handling by setting the server SQL mode appropriately. For more
information about data handling, see *Note constraints::, *Note
server-sql-mode::, and *Note insert::.


File: manual.info,  Node: portability,  Next: internal-use,  Prev: design-limitations,  Up: optimize-overview

7.1.2 Designing Applications for Portability
--------------------------------------------

Because all SQL servers implement different parts of standard SQL, it
takes work to write portable database applications. It is very easy to
achieve portability for very simple selects and inserts, but becomes
more difficult the more capabilities you require. If you want an
application that is fast with many database systems, it becomes even
more difficult.

All database systems have some weak points. That is, they have
different design compromises that lead to different behavior.

To make a complex application portable, you need to determine which SQL
servers it must work with, and then determine what features those
servers support. You can use the MySQL `crash-me' program to find
functions, types, and limits that you can use with a selection of
database servers. `crash-me' does not check for every possible feature,
but it is still reasonably comprehensive, performing about 450 tests.
An example of the type of information `crash-me' can provide is that you
should not use column names that are longer than 18 characters if you
want to be able to use Informix or DB2.

The `crash-me' program and the MySQL benchmarks are all very database
independent. By taking a look at how they are written, you can get a
feeling for what you must do to make your own applications database
independent. The programs can be found in the `sql-bench' directory of
MySQL source distributions. They are written in Perl and use the DBI
database interface. Use of DBI in itself solves part of the portability
problem because it provides database-independent access methods. See
*Note mysql-benchmarks::.

If you strive for database independence, you need to get a good feeling
for each SQL server's bottlenecks. For example, MySQL is very fast in
retrieving and updating rows for `MyISAM' tables, but has a problem in
mixing slow readers and writers on the same table. Transactional
database systems in general are not very good at generating summary
tables from log tables, because in this case row locking is almost
useless.

MySQL Enterprise

For expert advice on choosing the database engine suitable to your
circumstances subscribe to the MySQL Enterprise Monitor.  For more
information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

To make your application _really_ database independent, you should
define an easily extendable interface through which you manipulate your
data. For example, C++ is available on most systems, so it makes sense
to use a C++ class-based interface to the databases.

If you use some feature that is specific to a given database system
(such as the `REPLACE' statement, which is specific to MySQL), you
should implement the same feature for other SQL servers by coding an
alternative method. Although the alternative might be slower, it
enables the other servers to perform the same tasks.

With MySQL, you can use the `/*! */' syntax to add MySQL-specific
keywords to a statement. The code inside `/* */' is treated as a
comment (and ignored) by most other SQL servers. For information about
writing comments, see *Note comments::.

If high performance is more important than exactness, as for some Web
applications, it is possible to create an application layer that caches
all results to give you even higher performance. By letting old results
expire after a while, you can keep the cache reasonably fresh. This
provides a method to handle high load spikes, in which case you can
dynamically increase the cache size and set the expiration timeout
higher until things get back to normal.

In this case, the table creation information should contain information
about the initial cache size and how often the table should normally be
refreshed.

An attractive alternative to implementing an application cache is to
use the MySQL query cache. By enabling the query cache, the server
handles the details of determining whether a query result can be
reused. This simplifies your application. See *Note query-cache::.


File: manual.info,  Node: internal-use,  Next: mysql-benchmarks,  Prev: portability,  Up: optimize-overview

7.1.3 What We Have Used MySQL For
---------------------------------

This section describes an early application for MySQL.

During MySQL initial development, the features of MySQL were made to
fit our largest customer, which handled data warehousing for a couple
of the largest retailers in Sweden.

From all stores, we got weekly summaries of all bonus card
transactions, and were expected to provide useful information for the
store owners to help them find how their advertising campaigns were
affecting their own customers.

The volume of data was quite huge (about seven million summary
transactions per month), and we had data for 4-10 years that we needed
to present to the users. We got weekly requests from our customers, who
wanted instant access to new reports from this data.

We solved this problem by storing all information per month in
compressed `transaction tables.' We had a set of simple macros that
generated summary tables grouped by different criteria (product group,
customer id, store, and so on) from the tables in which the
transactions were stored. The reports were Web pages that were
dynamically generated by a small Perl script. This script parsed a Web
page, executed the SQL statements in it, and inserted the results. We
would have used PHP or `mod_perl' instead, but they were not available
at the time.

For graphical data, we wrote a simple tool in C that could process SQL
query results and produce GIF images based on those results. This tool
also was dynamically executed from the Perl script that parses the Web
pages.

In most cases, a new report could be created simply by copying an
existing script and modifying the SQL query that it used. In some
cases, we needed to add more columns to an existing summary table or
generate a new one. This also was quite simple because we kept all
transaction-storage tables on disk. (This amounted to about 50GB of
transaction tables and 200GB of other customer data.)

We also let our customers access the summary tables directly with ODBC
so that the advanced users could experiment with the data themselves.

This system worked well and we had no problems handling the data with
quite modest Sun Ultra SPARCstation hardware (2x200MHz). Eventually the
system was migrated to Linux.


File: manual.info,  Node: mysql-benchmarks,  Next: custom-benchmarks,  Prev: internal-use,  Up: optimize-overview

7.1.4 The MySQL Benchmark Suite
-------------------------------

This benchmark suite is meant to tell any user what operations a given
SQL implementation performs well or poorly. You can get a good idea for
how the benchmarks work by looking at the code and results in the
`sql-bench' directory in any MySQL source distribution.

Note that this benchmark is single-threaded, so it measures the minimum
time for the operations performed. We plan to add multi-threaded tests
to the benchmark suite in the future.

To use the benchmark suite, the following requirements must be
satisfied:

   * The benchmark suite is provided with MySQL source distributions.
     You can either download a released distribution from
     `http://dev.mysql.com/downloads/', or use the current development
     source tree. (See *Note installing-source-tree::.)

   * The benchmark scripts are written in Perl and use the Perl DBI
     module to access database servers, so DBI must be installed. You
     also need the server-specific DBD drivers for each of the servers
     you want to test. For example, to test MySQL, PostgreSQL, and DB2,
     you must have the `DBD::mysql', `DBD::Pg', and `DBD::DB2' modules
     installed. See *Note perl-support::.

After you obtain a MySQL source distribution, you can find the
benchmark suite located in its `sql-bench' directory. To run the
benchmark tests, build MySQL, and then change location into the
`sql-bench' directory and execute the `run-all-tests' script:

     shell> cd sql-bench
     shell> perl run-all-tests --server=SERVER_NAME

SERVER_NAME should be the name of one of the supported servers. To get
a list of all options and supported servers, invoke this command:

     shell> perl run-all-tests --help

The `crash-me' script also is located in the `sql-bench' directory.
`crash-me' tries to determine what features a database system supports
and what its capabilities and limitations are by actually running
queries. For example, it determines:

   * What data types are supported

   * How many indexes are supported

   * What functions are supported

   * How big a query can be

   * How big a `VARCHAR' column can be

For more information about benchmark results, visit
`http://www.mysql.com/why-mysql/benchmarks/'.


File: manual.info,  Node: custom-benchmarks,  Prev: mysql-benchmarks,  Up: optimize-overview

7.1.5 Using Your Own Benchmarks
-------------------------------

You should definitely benchmark your application and database to find
out where the bottlenecks are. After fixing one bottleneck (or by
replacing it with a `dummy' module), you can proceed to identify the
next bottleneck. Even if the overall performance for your application
currently is acceptable, you should at least make a plan for each
bottleneck and decide how to solve it if someday you really need the
extra performance.

For examples of portable benchmark programs, look at those in the MySQL
benchmark suite. See *Note mysql-benchmarks::. You can take any program
from this suite and modify it for your own needs. By doing this, you
can try different solutions to your problem and test which really is
fastest for you.

Another free benchmark suite is the Open Source Database Benchmark,
available at `http://osdb.sourceforge.net/'.

It is very common for a problem to occur only when the system is very
heavily loaded. We have had many customers who contact us when they
have a (tested) system in production and have encountered load
problems. In most cases, performance problems turn out to be due to
issues of basic database design (for example, table scans are not good
under high load) or problems with the operating system or libraries.
Most of the time, these problems would be much easier to fix if the
systems were not already in production.

To avoid problems like this, you should put some effort into
benchmarking your whole application under the worst possible load:

   * The `mysqlslap' program can be helpful for simulating a high load
     produced by multiple clients issuing queries simultaneously. See
     *Note mysqlslap::.

   * You can also try Super Smack, available at
     `http://jeremy.zawodny.com/mysql/super-smack/'.

As suggested by the names of these programs, they can bring a system to
its knees, so make sure to use them only on your development systems.


File: manual.info,  Node: query-speed,  Next: locking-issues,  Prev: optimize-overview,  Up: optimization

7.2 Optimizing `SELECT' and Other Statements
============================================

* Menu:

* using-explain::                Optimizing Queries with `EXPLAIN'
* estimating-performance::       Estimating Query Performance
* select-speed::                 Speed of `SELECT' Queries
* where-optimizations::          `WHERE' Clause Optimization
* range-optimization::           Range Optimization
* index-merge-optimization::     Index Merge Optimization
* condition-pushdown-optimization::  Condition Pushdown Optimization
* is-null-optimization::         `IS NULL' Optimization
* left-join-optimization::       `LEFT JOIN' and `RIGHT JOIN' Optimization
* nested-joins::                 Nested Join Optimization
* outer-join-simplification::    Outer Join Simplification
* order-by-optimization::        `ORDER BY' Optimization
* group-by-optimization::        `GROUP BY' Optimization
* distinct-optimization::        `DISTINCT' Optimization
* in-subquery-optimization::     Optimizing `IN'/`=ANY' Subqueries
* limit-optimization::           `LIMIT' Optimization
* how-to-avoid-table-scan::      How to Avoid Table Scans
* information-schema-optimization::  `INFORMATION_SCHEMA' Optimization
* insert-speed::                 Speed of `INSERT' Statements
* update-speed::                 Speed of `UPDATE' Statements
* delete-speed::                 Speed of `DELETE' Statements
* miscellaneous-optimization-tips::  Other Optimization Tips

First, one factor affects all statements: The more complex your
permissions setup, the more overhead you have. Using simpler
permissions when you issue `GRANT' statements enables MySQL to reduce
permission-checking overhead when clients execute statements. For
example, if you do not grant any table-level or column-level
privileges, the server need not ever check the contents of the
`tables_priv' and `columns_priv' tables. Similarly, if you place no
resource limits on any accounts, the server does not have to perform
resource counting. If you have a very high statement-processing load,
it may be worth the time to use a simplified grant structure to reduce
permission-checking overhead.

If your problem is with a specific MySQL expression or function, you
can perform a timing test by invoking the `BENCHMARK()' function using
the `mysql' client program. Its syntax is
`BENCHMARK(LOOP_COUNT,EXPRESSION)'.  The return value is always zero,
but `mysql' prints a line displaying approximately how long the
statement took to execute. For example:

     mysql> SELECT BENCHMARK(1000000,1+1);
     +------------------------+
     | BENCHMARK(1000000,1+1) |
     +------------------------+
     |                      0 |
     +------------------------+
     1 row in set (0.32 sec)

This result was obtained on a Pentium II 400MHz system. It shows that
MySQL can execute 1,000,000 simple addition expressions in 0.32 seconds
on that system.

All MySQL functions should be highly optimized, but there may be some
exceptions. `BENCHMARK()' is an excellent tool for finding out if some
function is a problem for your queries.


File: manual.info,  Node: using-explain,  Next: estimating-performance,  Prev: query-speed,  Up: query-speed

7.2.1 Optimizing Queries with `EXPLAIN'
---------------------------------------

The `EXPLAIN' statement can be used either as a synonym for `DESCRIBE'
or as a way to obtain information about how MySQL executes a `SELECT'
statement:

   * `EXPLAIN TBL_NAME' is synonymous with `DESCRIBE TBL_NAME' or `SHOW
     COLUMNS FROM TBL_NAME':

          EXPLAIN TBL_NAME

   * When you precede a `SELECT' statement with the keyword `EXPLAIN',
     MySQL displays information from the optimizer about the query
     execution plan. That is, MySQL explains how it would process the
     `SELECT', including information about how tables are joined and in
     which order:

          EXPLAIN [EXTENDED | PARTITIONS] SELECT SELECT_OPTIONS

   * `EXPLAIN PARTITIONS' is available beginning with MySQL 5.1.5. It
     is useful only when examining queries involving partitioned
     tables. For details, see *Note partitioning-info::.

This section describes the second use of `EXPLAIN' for obtaining query
execution plan information. See also *Note explain::. For a description
of the `DESCRIBE' and `SHOW COLUMNS' statements, see *Note describe::,
and *Note show-columns::.

With the help of `EXPLAIN', you can see where you should add indexes to
tables to get a faster `SELECT' that uses indexes to find rows. You can
also use `EXPLAIN' to check whether the optimizer joins the tables in
an optimal order. To give a hint to the optimizer to use a join order
corresponding to the order in which the tables are named in the `SELECT'
statement, begin the statement with `SELECT STRAIGHT_JOIN' rather than
just `SELECT'. (See *Note select::.)

If you have a problem with indexes not being used when you believe that
they should be, you should run `ANALYZE TABLE' to update table
statistics such as cardinality of keys, that can affect the choices the
optimizer makes. See *Note analyze-table::.

`EXPLAIN' returns a row of information for each table used in the
`SELECT' statement. The tables are listed in the output in the order
that MySQL would read them while processing the query. MySQL resolves
all joins using a _single-sweep multi-join_ method.  This means that
MySQL reads a row from the first table, and then finds a matching row
in the second table, the third table, and so on. When all tables are
processed, MySQL outputs the selected columns and backtracks through
the table list until a table is found for which there are more matching
rows. The next row is read from this table and the process continues
with the next table.

When the `EXTENDED' keyword is used, `EXPLAIN' produces extra
information that can be viewed by issuing a `SHOW WARNINGS' statement
following the `EXPLAIN' statement.  This information displays how the
optimizer qualifies table and column names in the `SELECT' statement,
what the `SELECT' looks like after the application of rewriting and
optimization rules, and possibly other notes about the optimization
process. `EXPLAIN EXTENDED' also displays the `filtered' column as of
MySQL 5.1.12.

*Note*:

You cannot use the `EXTENDED' and `PARTITIONS' keywords together in the
same `EXPLAIN' statement.

Each output row from `EXPLAIN' provides information about one table,
and each row contains the following columns:

   * `id'

     The `SELECT' identifier. This is the sequential number of the
     `SELECT' within the query.

   * `select_type'

     The type of `SELECT', which can be any of those shown in the
     following table:

     `SIMPLE'          Simple `SELECT' (not using `UNION' or subqueries)
     `PRIMARY'         Outermost `SELECT'
     `UNION'           Second or later `SELECT' statement in a `UNION'
     `DEPENDENT UNION' Second or later `SELECT' statement in a `UNION',
                       dependent on outer query
     `UNION RESULT'    Result of a `UNION'.
     `SUBQUERY'        First `SELECT' in subquery
     `DEPENDENT        First `SELECT' in subquery, dependent on outer
     SUBQUERY'         query
     `DERIVED'         Derived table `SELECT' (subquery in `FROM' clause)
     `UNCACHEABLE      A subquery for which the result cannot be cached
     SUBQUERY'         and must be re-evaluated for each row of the
                       outer query
     `UNCACHEABLE      The second or later select in a `UNION' that
     UNION'            belongs to an uncacheable subquery (see
                       `UNCACHEABLE SUBQUERY')

     `DEPENDENT' typically signifies the use of a correlated subquery.
     See *Note correlated-subqueries::.

     `DEPENDENT SUBQUERY' evaluation differs from `UNCACHEABLE
     SUBQUERY' evaluation. For `DEPENDENT SUBQUERY', the subquery is
     re-evaluated only once for each set of different values of the
     variables from its outer context. For `UNCACHEABLE SUBQUERY', the
     subquery is re-evaluated for each row of the outer context.
     Cacheability of subqueries is subject to the restrictions detailed
     in *Note query-cache-how::. For example, referring to user
     variables makes a subquery uncacheable.

   * `table'

     The table to which the row of output refers.

   * `type'

     The join type. The different join types are listed here, ordered
     from the best type to the worst:

        * `system'

          The table has only one row (= system table). This is a
          special case of the `const' join type.

        * `const'

          The table has at most one matching row, which is read at the
          start of the query. Because there is only one row, values
          from the column in this row can be regarded as constants by
          the rest of the optimizer.  `const' tables are very fast
          because they are read only once.

          `const' is used when you compare all parts of a `PRIMARY KEY'
          or `UNIQUE' index to constant values. In the following
          queries, TBL_NAME can be used as a `const' table:

               SELECT * FROM TBL_NAME WHERE PRIMARY_KEY=1;

               SELECT * FROM TBL_NAME
                 WHERE PRIMARY_KEY_PART1=1 AND PRIMARY_KEY_PART2=2;

        * `eq_ref'

          One row is read from this table for each combination of rows
          from the previous tables. Other than the `system' and `const'
          types, this is the best possible join type. It is used when
          all parts of an index are used by the join and the index is a
          `PRIMARY KEY' or `UNIQUE' index.

          `eq_ref' can be used for indexed columns that are compared
          using the `=' operator. The comparison value can be a
          constant or an expression that uses columns from tables that
          are read before this table. In the following examples, MySQL
          can use an `eq_ref' join to process REF_TABLE:

               SELECT * FROM REF_TABLE,OTHER_TABLE
                 WHERE REF_TABLE.KEY_COLUMN=OTHER_TABLE.COLUMN;

               SELECT * FROM REF_TABLE,OTHER_TABLE
                 WHERE REF_TABLE.KEY_COLUMN_PART1=OTHER_TABLE.COLUMN
                 AND REF_TABLE.KEY_COLUMN_PART2=1;

        * `ref'

          All rows with matching index values are read from this table
          for each combination of rows from the previous tables. `ref'
          is used if the join uses only a leftmost prefix of the key or
          if the key is not a `PRIMARY KEY' or `UNIQUE' index (in other
          words, if the join cannot select a single row based on the
          key value).  If the key that is used matches only a few rows,
          this is a good join type.

          `ref' can be used for indexed columns that are compared using
          the `=' or `<=>' operator. In the following examples, MySQL
          can use a `ref' join to process REF_TABLE:

               SELECT * FROM REF_TABLE WHERE KEY_COLUMN=EXPR;

               SELECT * FROM REF_TABLE,OTHER_TABLE
                 WHERE REF_TABLE.KEY_COLUMN=OTHER_TABLE.COLUMN;

               SELECT * FROM REF_TABLE,OTHER_TABLE
                 WHERE REF_TABLE.KEY_COLUMN_PART1=OTHER_TABLE.COLUMN
                 AND REF_TABLE.KEY_COLUMN_PART2=1;

        * `fulltext'

          The join is performed using a `FULLTEXT' index.

        * `ref_or_null'

          This join type is like `ref', but with the addition that
          MySQL does an extra search for rows that contain `NULL'
          values. This join type optimization is used most often in
          resolving subqueries. In the following examples, MySQL can
          use a `ref_or_null' join to process REF_TABLE:

               SELECT * FROM REF_TABLE
                 WHERE KEY_COLUMN=EXPR OR KEY_COLUMN IS NULL;

          See *Note is-null-optimization::.

        * `index_merge'

          This join type indicates that the Index Merge optimization is
          used. In this case, the `key' column in the output row
          contains a list of indexes used, and `key_len' contains a
          list of the longest key parts for the indexes used. For more
          information, see *Note index-merge-optimization::.

        * `unique_subquery'

          This type replaces `ref' for some `IN' subqueries of the
          following form:

               VALUE IN (SELECT PRIMARY_KEY FROM SINGLE_TABLE WHERE SOME_EXPR)

          `unique_subquery' is just an index lookup function that
          replaces the subquery completely for better efficiency.

        * `index_subquery'

          This join type is similar to `unique_subquery'. It replaces
          `IN' subqueries, but it works for non-unique indexes in
          subqueries of the following form:

               VALUE IN (SELECT KEY_COLUMN FROM SINGLE_TABLE WHERE SOME_EXPR)

        * `range'

          Only rows that are in a given range are retrieved, using an
          index to select the rows. The `key' column in the output row
          indicates which index is used.  The `key_len' contains the
          longest key part that was used. The `ref' column is `NULL'
          for this type.

          `range' can be used when a key column is compared to a
          constant using any of the `=', `<>', `>', `>=', `<', `<=',
          `IS NULL', `<=>', `BETWEEN', or `IN()' operators:

               SELECT * FROM TBL_NAME
                 WHERE KEY_COLUMN = 10;

               SELECT * FROM TBL_NAME
                 WHERE KEY_COLUMN BETWEEN 10 and 20;

               SELECT * FROM TBL_NAME
                 WHERE KEY_COLUMN IN (10,20,30);

               SELECT * FROM TBL_NAME
                 WHERE KEY_PART1= 10 AND KEY_PART2 IN (10,20,30);

        * `index'

          This join type is the same as `ALL', except that only the
          index tree is scanned. This usually is faster than `ALL'
          because the index file usually is smaller than the data file.

          MySQL can use this join type when the query uses only columns
          that are part of a single index.

        * `ALL'

          A full table scan is done for each combination of rows from
          the previous tables. This is normally not good if the table
          is the first table not marked `const', and usually _very_ bad
          in all other cases.  Normally, you can avoid `ALL' by adding
          indexes that allow row retrieval from the table based on
          constant values or column values from earlier tables.

   * `possible_keys'

     The `possible_keys' column indicates which indexes MySQL can
     choose from use to find the rows in this table. Note that this
     column is totally independent of the order of the tables as
     displayed in the output from `EXPLAIN'. That means that some of
     the keys in `possible_keys' might not be usable in practice with
     the generated table order.

     If this column is `NULL', there are no relevant indexes. In this
     case, you may be able to improve the performance of your query by
     examining the `WHERE' clause to check whether it refers to some
     column or columns that would be suitable for indexing. If so,
     create an appropriate index and check the query with `EXPLAIN'
     again. See *Note alter-table::.

     To see what indexes a table has, use `SHOW INDEX FROM TBL_NAME'.

   * `key'

     The `key' column indicates the key (index) that MySQL actually
     decided to use. If MySQL decides to use one of the `possible_keys'
     indexes to look up rows, that index is listed as the key value.

     It is possible that `key' will name an index that is not present
     in the `possible_keys' value. This can happen if none of the
     `possible_keys' indexes are suitable for looking up rows, but all
     the columns selected by the query are columns of some other index.
     That is, the named index covers the selected columns, so although
     it is not used to determine which rows to retrieve, an index scan
     is more efficient than a data row scan.

     For `InnoDB', a secondary index might cover the selected columns
     even if the query also selects the primary key because `InnoDB'
     stores the primary key value with each secondary index. If `key'
     is `NULL', MySQL found no index to use for executing the query more
     efficiently.

     To force MySQL to use or ignore an index listed in the
     `possible_keys' column, use `FORCE INDEX', `USE INDEX', or `IGNORE
     INDEX' in your query. See *Note index-hints::.

     For `MyISAM' tables, running `ANALYZE TABLE' helps the optimizer
     choose better indexes. For `MyISAM' tables, `myisamchk --analyze'
     does the same. See *Note analyze-table::, and *Note
     table-maintenance::.

   * `key_len'

     The `key_len' column indicates the length of the key that MySQL
     decided to use. The length is `NULL' if the `key' column says
     `NULL'. Note that the value of `key_len' enables you to determine
     how many parts of a multiple-part key MySQL actually uses.

   * `ref'

     The `ref' column shows which columns or constants are compared to
     the index named in the `key' column to select rows from the table.

   * `rows'

     The `rows' column indicates the number of rows MySQL believes it
     must examine to execute the query.

   * `filtered'

     The `filtered' column indicates an estimated percentage of table
     rows that will be filtered by the table condition. That is, `rows'
     shows the estimated number of rows examined and `rows' x `filtered'
     / `100' shows the number of rows that will be joined with previous
     tables. This column is displayed if you use `EXPLAIN EXTENDED'.
     (New in MySQL 5.1.12)

   * `Extra'

     This column contains additional information about how MySQL
     resolves the query. The following list explains the values that
     can appear in this column. If you want to make your queries as
     fast as possible, you should look out for `Extra' values of `Using
     filesort' and `Using temporary'.

        * `Distinct'

          MySQL is looking for distinct values, so it stops searching
          for more rows for the current row combination after it has
          found the first matching row.

        * `Full scan on NULL key'

          This occurs for subquery optimization as a fallback strategy
          when the optimizer cannot use an index-lookup access method.

        * `Impossible WHERE noticed after reading const tables'

          MySQL has read all `const' (and `system') tables and notice
          that the `WHERE' clause is always false.

        * `No tables'

          The query has no `FROM' clause, or has a `FROM DUAL' clause.

        * `Not exists'

          MySQL was able to do a `LEFT JOIN' optimization on the query
          and does not examine more rows in this table for the previous
          row combination after it finds one row that matches the `LEFT
          JOIN' criteria. Here is an example of the type of query that
          can be optimized this way:

               SELECT * FROM t1 LEFT JOIN t2 ON t1.id=t2.id
                 WHERE t2.id IS NULL;

          Assume that `t2.id' is defined as `NOT NULL'. In this case,
          MySQL scans `t1' and looks up the rows in `t2' using the
          values of `t1.id'. If MySQL finds a matching row in `t2', it
          knows that `t2.id' can never be `NULL', and does not scan
          through the rest of the rows in `t2' that have the same `id'
          value. In other words, for each row in `t1', MySQL needs to do
          only a single lookup in `t2', regardless of how many rows
          actually match in `t2'.

        * `Range checked for each record (index map: N)'

          MySQL found no good index to use, but found that some of
          indexes might be used after column values from preceding
          tables are known. For each row combination in the preceding
          tables, MySQL checks whether it is possible to use a `range'
          or `index_merge' access method to retrieve rows. This is not
          very fast, but is faster than performing a join with no index
          at all. The applicability criteria are as described in *Note
          range-optimization::, and *Note index-merge-optimization::,
          with the exception that all column values for the preceding
          table are known and considered to be constants.

          Indexes are numbered beginning with 1, in the same order as
          shown by `SHOW INDEX' for the table.  The index map value N
          is a bitmask value that indicates which indexes are
          candidates. For example, a value of `0x19' (binary 11001)
          means that indexes 1, 4, and 5 will be considered.

        * `Scanned N databases'

          This indicates how many directory scans the server performs
          when processing a query for `INFORMATION_SCHEMA' tables, as
          described in *Note information-schema-optimization::. The
          value of N can be 0, 1, or `all'.

        * `Select tables optimized away'

          The query contained only aggregate functions (`MIN()',
          `MAX()') that were all resolved using an index, or `COUNT(*)'
          for `MyISAM', and no `GROUP BY' clause. The optimizer
          determined that only one row should be returned.

        * `Skip_open_table', `Open_frm_only', `Open_trigger_only',
          `Open_full_table'

          These values indicate file-opening optimizations that apply
          to queries for `INFORMATION_SCHEMA' tables, as described in
          *Note information-schema-optimization::.

             * `Skip_open_table': Table files do not need to be opened.
               The information has already become available within the
               query by scanning the database directory.

             * `Open_frm_only': Only the table's `.frm' file need be
               opened.

             * `Open_trigger_only': Only the table's `.TRG' file need be
               opened.

             * `Open_full_table': The unoptimized information lookup.
               The `.frm', `.MYD', and `.MYI' files must be opened.

        * `Using filesort'

          MySQL must do an extra pass to find out how to retrieve the
          rows in sorted order. The sort is done by going through all
          rows according to the join type and storing the sort key and
          pointer to the row for all rows that match the `WHERE'
          clause. The keys then are sorted and the rows are retrieved
          in sorted order.  See *Note order-by-optimization::.

        * `Using index'

          The column information is retrieved from the table using only
          information in the index tree without having to do an
          additional seek to read the actual row. This strategy can be
          used when the query uses only columns that are part of a
          single index.

          For `InnoDB' tables that have a user-defined clustered index,
          that index can be used even when `Using index' is absent from
          the `Extra' column. This is the case if if `type' is `index'
          and `key' is `PRIMARY'.

        * `Using index for group-by'

          Similar to the `Using index' table access method, `Using
          index for group-by' indicates that MySQL found an index that
          can be used to retrieve all columns of a `GROUP BY' or
          `DISTINCT' query without any extra disk access to the actual
          table. Additionally, the index is used in the most efficient
          way so that for each group, only a few index entries are
          read. For details, see *Note group-by-optimization::.

        * `Using join buffer'

          Tables are read in portions into the join buffer, and then
          their rows are used from the buffer to perform the join.

        * `Using sort_union(...)', `Using union(...)', `Using
          intersect(...)'

          These indicate how index scans are merged for the
          `index_merge' join type. See *Note index-merge-optimization::.

        * `Using temporary'

          To resolve the query, MySQL needs to create a temporary table
          to hold the result. This typically happens if the query
          contains `GROUP BY' and `ORDER BY' clauses that list columns
          differently.

        * `Using where'

          A `WHERE' clause is used to restrict which rows to match
          against the next table or send to the client. Unless you
          specifically intend to fetch or examine all rows from the
          table, you may have something wrong in your query if the
          `Extra' value is not `Using where' and the table join type is
          `ALL' or `index'.

        * `Using where with pushed condition'

          This item applies to `NDBCLUSTER' tables _only_. It means
          that MySQL Cluster is using the Condition Pushdown
          optimization to improve the efficiency of a direct comparison
          between a non-indexed column and a constant. In such cases,
          the condition is `pushed down' to the cluster's data nodes
          and is evaluated on all data nodes simultaneously. This
          eliminates the need to send non-matching rows over the
          network, and can speed up such queries by a factor of 5 to 10
          times over cases where Condition Pushdown could be but is not
          used. For more information, see *Note
          condition-pushdown-optimization::.

You can get a good indication of how good a join is by taking the
product of the values in the `rows' column of the `EXPLAIN' output.
This should tell you roughly how many rows MySQL must examine to
execute the query.  If you restrict queries with the `max_join_size'
system variable, this row product also is used to determine which
multiple-table `SELECT' statements to execute and which to abort. See
*Note server-parameters::.

The following example shows how a multiple-table join can be optimized
progressively based on the information provided by `EXPLAIN'.

Suppose that you have the `SELECT' statement shown here and that you
plan to examine it using `EXPLAIN':

     EXPLAIN SELECT tt.TicketNumber, tt.TimeIn,
                    tt.ProjectReference, tt.EstimatedShipDate,
                    tt.ActualShipDate, tt.ClientID,
                    tt.ServiceCodes, tt.RepetitiveID,
                    tt.CurrentProcess, tt.CurrentDPPerson,
                    tt.RecordVolume, tt.DPPrinted, et.COUNTRY,
                    et_1.COUNTRY, do.CUSTNAME
             FROM tt, et, et AS et_1, do
             WHERE tt.SubmitTime IS NULL
               AND tt.ActualPC = et.EMPLOYID
               AND tt.AssignedPC = et_1.EMPLOYID
               AND tt.ClientID = do.CUSTNMBR;

For this example, make the following assumptions:

   * The columns being compared have been declared as follows:

     *Table* *Column*          *Data Type*
     `tt'    `ActualPC'        `CHAR(10)'
     `tt'    `AssignedPC'      `CHAR(10)'
     `tt'    `ClientID'        `CHAR(10)'
     `et'    `EMPLOYID'        `CHAR(15)'
     `do'    `CUSTNMBR'        `CHAR(15)'

   * The tables have the following indexes:

     *Table* *Index*
     `tt'    `ActualPC'
     `tt'    `AssignedPC'
     `tt'    `ClientID'
     `et'    `EMPLOYID' (primary key)
     `do'    `CUSTNMBR' (primary key)

   * The `tt.ActualPC' values are not evenly distributed.

Initially, before any optimizations have been performed, the `EXPLAIN'
statement produces the following information:

     table type possible_keys key  key_len ref  rows  Extra
     et    ALL  PRIMARY       NULL NULL    NULL 74
     do    ALL  PRIMARY       NULL NULL    NULL 2135
     et_1  ALL  PRIMARY       NULL NULL    NULL 74
     tt    ALL  AssignedPC,   NULL NULL    NULL 3872
                ClientID,
                ActualPC
           Range checked for each record (index map: 0x23)

Because `type' is `ALL' for each table, this output indicates that
MySQL is generating a Cartesian product of all the tables; that is,
every combination of rows. This takes quite a long time, because the
product of the number of rows in each table must be examined. For the
case at hand, this product is 74 x 2135 x 74 x 3872 = 45,268,558,720
rows. If the tables were bigger, you can only imagine how long it would
take.

One problem here is that MySQL can use indexes on columns more
efficiently if they are declared as the same type and size. In this
context, `VARCHAR' and `CHAR' are considered the same if they are
declared as the same size. `tt.ActualPC' is declared as `CHAR(10)' and
`et.EMPLOYID' is `CHAR(15)', so there is a length mismatch.

To fix this disparity between column lengths, use `ALTER TABLE' to
lengthen `ActualPC' from 10 characters to 15 characters:

     mysql> ALTER TABLE tt MODIFY ActualPC VARCHAR(15);

Now `tt.ActualPC' and `et.EMPLOYID' are both `VARCHAR(15)'. Executing
the `EXPLAIN' statement again produces this result:

     table type   possible_keys key     key_len ref         rows    Extra
     tt    ALL    AssignedPC,   NULL    NULL    NULL        3872    Using
                  ClientID,                                         where
                  ActualPC
     do    ALL    PRIMARY       NULL    NULL    NULL        2135
           Range checked for each record (index map: 0x1)
     et_1  ALL    PRIMARY       NULL    NULL    NULL        74
           Range checked for each record (index map: 0x1)
     et    eq_ref PRIMARY       PRIMARY 15      tt.ActualPC 1

This is not perfect, but is much better: The product of the `rows'
values is less by a factor of 74. This version executes in a couple of
seconds.

A second alteration can be made to eliminate the column length
mismatches for the `tt.AssignedPC = et_1.EMPLOYID' and `tt.ClientID =
do.CUSTNMBR' comparisons:

     mysql> ALTER TABLE tt MODIFY AssignedPC VARCHAR(15),
         ->                MODIFY ClientID   VARCHAR(15);

After that modification, `EXPLAIN' produces the output shown here:

     table type   possible_keys key      key_len ref           rows Extra
     et    ALL    PRIMARY       NULL     NULL    NULL          74
     tt    ref    AssignedPC,   ActualPC 15      et.EMPLOYID   52   Using
                  ClientID,                                         where
                  ActualPC
     et_1  eq_ref PRIMARY       PRIMARY  15      tt.AssignedPC 1
     do    eq_ref PRIMARY       PRIMARY  15      tt.ClientID   1

At this point, the query is optimized almost as well as possible. The
remaining problem is that, by default, MySQL assumes that values in the
`tt.ActualPC' column are evenly distributed, and that is not the case
for the `tt' table. Fortunately, it is easy to tell MySQL to analyze
the key distribution:

     mysql> ANALYZE TABLE tt;

With the additional index information, the join is perfect and
`EXPLAIN' produces this result:

     table type   possible_keys key     key_len ref           rows Extra
     tt    ALL    AssignedPC    NULL    NULL    NULL          3872 Using
                  ClientID,                                        where
                  ActualPC
     et    eq_ref PRIMARY       PRIMARY 15      tt.ActualPC   1
     et_1  eq_ref PRIMARY       PRIMARY 15      tt.AssignedPC 1
     do    eq_ref PRIMARY       PRIMARY 15      tt.ClientID   1

Note that the `rows' column in the output from `EXPLAIN' is an educated
guess from the MySQL join optimizer. You should check whether the
numbers are even close to the truth by comparing the `rows' product
with the actual number of rows that the query returns.  If the numbers
are quite different, you might get better performance by using
`STRAIGHT_JOIN' in your `SELECT' statement and trying to list the
tables in a different order in the `FROM' clause.

It is possible in some cases to execute statements that modify data
when `EXPLAIN SELECT' is used with a subquery; for more information, see
*Note unnamed-views::.

MySQL Enterprise

Subscribers to the MySQL Enterprise Monitor regularly receive expert
advice on optimization. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: estimating-performance,  Next: select-speed,  Prev: using-explain,  Up: query-speed

7.2.2 Estimating Query Performance
----------------------------------

In most cases, you can estimate query performance by counting disk
seeks. For small tables, you can usually find a row in one disk seek
(because the index is probably cached). For bigger tables, you can
estimate that, using B-tree indexes, you need this many seeks to find a
row: `log(ROW_COUNT) / log(INDEX_BLOCK_LENGTH / 3 x 2 / (INDEX_LENGTH +
DATA_POINTER_LENGTH)) + 1'.

In MySQL, an index block is usually 1,024 bytes and the data pointer is
usually four bytes. For a 500,000-row table with an index length of
three bytes (the size of `MEDIUMINT'), the formula indicates
`log(500,000)/log(1024/3x2/(3+4)) + 1' = `4' seeks.

This index would require storage of about 500,000 x 7 x 3/2 = 5.2MB
(assuming a typical index buffer fill ratio of 2/3), so you probably
have much of the index in memory and so need only one or two calls to
read data to find the row.

For writes, however, you need four seek requests to find where to place
a new index value and normally two seeks to update the index and write
the row.

Note that the preceding discussion does not mean that your application
performance slowly degenerates by log N. As long as everything is
cached by the OS or the MySQL server, things become only marginally
slower as the table gets bigger. After the data gets too big to be
cached, things start to go much slower until your applications are
bound only by disk seeks (which increase by log N). To avoid this,
increase the key cache size as the data grows. For `MyISAM' tables, the
key cache size is controlled by the `key_buffer_size' system variable.
See *Note server-parameters::.

MySQL Enterprise

The MySQL Enterprise Monitor provides a number of advisors specifically
designed to improve query performance. For more information see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: select-speed,  Next: where-optimizations,  Prev: estimating-performance,  Up: query-speed

7.2.3 Speed of `SELECT' Queries
-------------------------------

In general, when you want to make a slow `SELECT ...  WHERE' query
faster, the first thing to check is whether you can add an index. All
references between different tables should usually be done with
indexes. You can use the `EXPLAIN' statement to determine which indexes
are used for a `SELECT'. See *Note using-explain::, and *Note
mysql-indexes::.

Some general tips for speeding up queries on `MyISAM' tables:

   * To help MySQL better optimize queries, use `ANALYZE TABLE' or run
     `myisamchk --analyze' on a table after it has been loaded with
     data. This updates a value for each index part that indicates the
     average number of rows that have the same value. (For unique
     indexes, this is always 1.) MySQL uses this to decide which index
     to choose when you join two tables based on a non-constant
     expression. You can check the result from the table analysis by
     using `SHOW INDEX FROM TBL_NAME' and examining the `Cardinality'
     value.  `myisamchk --description --verbose' shows index
     distribution information.

   * To sort an index and data according to an index, use `myisamchk
     --sort-index --sort-records=1' (assuming that you want to sort on
     index 1). This is a good way to make queries faster if you have a
     unique index from which you want to read all rows in order
     according to the index. The first time you sort a large table this
     way, it may take a long time.


File: manual.info,  Node: where-optimizations,  Next: range-optimization,  Prev: select-speed,  Up: query-speed

7.2.4 `WHERE' Clause Optimization
---------------------------------

This section discusses optimizations that can be made for processing
`WHERE' clauses. The examples use `SELECT' statements, but the same
optimizations apply for `WHERE' clauses in `DELETE' and `UPDATE'
statements.

Work on the MySQL optimizer is ongoing, so this section is incomplete.
MySQL performs a great many optimizations, not all of which are
documented here.

Some of the optimizations performed by MySQL follow:

   * Removal of unnecessary parentheses:

             ((a AND b) AND c OR (((a AND b) AND (c AND d))))
          -> (a AND b AND c) OR (a AND b AND c AND d)

   * Constant folding:

             (a<b AND b=c) AND a=5
          -> b>5 AND b=c AND a=5

   * Constant condition removal (needed because of constant folding):

             (B>=5 AND B=5) OR (B=6 AND 5=5) OR (B=7 AND 5=6)
          -> B=5 OR B=6

   * Constant expressions used by indexes are evaluated only once.

   * `COUNT(*)' on a single table without a `WHERE' is retrieved
     directly from the table information for `MyISAM' and `MEMORY'
     tables. This is also done for any `NOT NULL' expression when used
     with only one table.

   * Early detection of invalid constant expressions. MySQL quickly
     detects that some `SELECT' statements are impossible and returns
     no rows.

   * `HAVING' is merged with `WHERE' if you do not use `GROUP BY' or
     aggregate functions (`COUNT()', `MIN()', and so on).

   * For each table in a join, a simpler `WHERE' is constructed to get
     a fast `WHERE' evaluation for the table and also to skip rows as
     soon as possible.

   * All constant tables are read first before any other tables in the
     query. A constant table is any of the following:

        * An empty table or a table with one row.

        * A table that is used with a `WHERE' clause on a `PRIMARY KEY'
          or a `UNIQUE' index, where all index parts are compared to
          constant expressions and are defined as `NOT NULL'.

     All of the following tables are used as constant tables:

          SELECT * FROM t WHERE PRIMARY_KEY=1;
          SELECT * FROM t1,t2
            WHERE t1.PRIMARY_KEY=1 AND t2.PRIMARY_KEY=t1.id;

   * The best join combination for joining the tables is found by
     trying all possibilities. If all columns in `ORDER BY' and `GROUP
     BY' clauses come from the same table, that table is preferred
     first when joining.

   * If there is an `ORDER BY' clause and a different `GROUP BY'
     clause, or if the `ORDER BY' or `GROUP BY' contains columns from
     tables other than the first table in the join queue, a temporary
     table is created.

   * If you use the `SQL_SMALL_RESULT' option, MySQL uses an in-memory
     temporary table.

   * Each table index is queried, and the best index is used unless the
     optimizer believes that it is more efficient to use a table scan.
     At one time, a scan was used based on whether the best index
     spanned more than 30% of the table, but a fixed percentage no
     longer determines the choice between using an index or a scan. The
     optimizer now is more complex and bases its estimate on additional
     factors such as table size, number of rows, and I/O block size.

   * In some cases, MySQL can read rows from the index without even
     consulting the data file. If all columns used from the index are
     numeric, only the index tree is used to resolve the query.

   * Before each row is output, those that do not match the `HAVING'
     clause are skipped.

Some examples of queries that are very fast:

     SELECT COUNT(*) FROM TBL_NAME;

     SELECT MIN(KEY_PART1),MAX(KEY_PART1) FROM TBL_NAME;

     SELECT MAX(KEY_PART2) FROM TBL_NAME
       WHERE KEY_PART1=CONSTANT;

     SELECT ... FROM TBL_NAME
       ORDER BY KEY_PART1,KEY_PART2,... LIMIT 10;

     SELECT ... FROM TBL_NAME
       ORDER BY KEY_PART1 DESC, KEY_PART2 DESC, ... LIMIT 10;

MySQL resolves the following queries using only the index tree,
assuming that the indexed columns are numeric:

     SELECT KEY_PART1,KEY_PART2 FROM TBL_NAME WHERE KEY_PART1=VAL;

     SELECT COUNT(*) FROM TBL_NAME
       WHERE KEY_PART1=VAL1 AND KEY_PART2=VAL2;

     SELECT KEY_PART2 FROM TBL_NAME GROUP BY KEY_PART1;

The following queries use indexing to retrieve the rows in sorted order
without a separate sorting pass:

     SELECT ... FROM TBL_NAME
       ORDER BY KEY_PART1,KEY_PART2,... ;

     SELECT ... FROM TBL_NAME
       ORDER BY KEY_PART1 DESC, KEY_PART2 DESC, ... ;


File: manual.info,  Node: range-optimization,  Next: index-merge-optimization,  Prev: where-optimizations,  Up: query-speed

7.2.5 Range Optimization
------------------------

* Menu:

* range-access-single-part::     The Range Access Method for Single-Part Indexes
* range-access-multi-part::      The Range Access Method for Multiple-Part Indexes

The `range' access method uses a single index to retrieve a subset of
table rows that are contained within one or several index value
intervals. It can be used for a single-part or multiple-part index. The
following sections give a detailed description of how intervals are
extracted from the `WHERE' clause.


File: manual.info,  Node: range-access-single-part,  Next: range-access-multi-part,  Prev: range-optimization,  Up: range-optimization

7.2.5.1 The Range Access Method for Single-Part Indexes
.......................................................

For a single-part index, index value intervals can be conveniently
represented by corresponding conditions in the `WHERE' clause, so we
speak of _range conditions_ rather than `intervals.'

The definition of a range condition for a single-part index is as
follows:

   * For both `BTREE' and `HASH' indexes, comparison of a key part with
     a constant value is a range condition when using the `=', `<=>',
     `IN()', `IS NULL', or `IS NOT NULL' operators.

   * For `BTREE' indexes, comparison of a key part with a constant
     value is a range condition when using the `>', `<', `>=', `<=',
     `BETWEEN', `!=', or `<>' operators, or `LIKE' comparisons if the
     argument to `LIKE' is a constant string that does not start with a
     wildcard character.

   * For all types of indexes, multiple range conditions combined with
     `OR' or `AND' form a range condition.

`Constant value' in the preceding descriptions means one of the
following:

   * A constant from the query string

   * A column of a `const' or `system' table from the same join

   * The result of an uncorrelated subquery

   * Any expression composed entirely from subexpressions of the
     preceding types

Here are some examples of queries with range conditions in the `WHERE'
clause:

     SELECT * FROM t1
       WHERE KEY_COL > 1
       AND KEY_COL < 10;

     SELECT * FROM t1
       WHERE KEY_COL = 1
       OR KEY_COL IN (15,18,20);

     SELECT * FROM t1
       WHERE KEY_COL LIKE 'ab%'
       OR KEY_COL BETWEEN 'bar' AND 'foo';

Note that some non-constant values may be converted to constants during
the constant propagation phase.

MySQL tries to extract range conditions from the `WHERE' clause for
each of the possible indexes. During the extraction process, conditions
that cannot be used for constructing the range condition are dropped,
conditions that produce overlapping ranges are combined, and conditions
that produce empty ranges are removed.

Consider the following statement, where `key1' is an indexed column and
`nonkey' is not indexed:

     SELECT * FROM t1 WHERE
       (key1 < 'abc' AND (key1 LIKE 'abcde%' OR key1 LIKE '%b')) OR
       (key1 < 'bar' AND nonkey = 4) OR
       (key1 < 'uux' AND key1 > 'z');

The extraction process for key `key1' is as follows:

  1. Start with original `WHERE' clause:

          (key1 < 'abc' AND (key1 LIKE 'abcde%' OR key1 LIKE '%b')) OR
          (key1 < 'bar' AND nonkey = 4) OR
          (key1 < 'uux' AND key1 > 'z')

  2. Remove `nonkey = 4' and `key1 LIKE '%b'' because they cannot be
     used for a range scan. The correct way to remove them is to replace
     them with `TRUE', so that we do not miss any matching rows when
     doing the range scan. Having replaced them with `TRUE', we get:

          (key1 < 'abc' AND (key1 LIKE 'abcde%' OR TRUE)) OR
          (key1 < 'bar' AND TRUE) OR
          (key1 < 'uux' AND key1 > 'z')

  3. Collapse conditions that are always true or false:

        * `(key1 LIKE 'abcde%' OR TRUE)' is always true

        * `(key1 < 'uux' AND key1 > 'z')' is always false

     Replacing these conditions with constants, we get:

          (key1 < 'abc' AND TRUE) OR (key1 < 'bar' AND TRUE) OR (FALSE)

     Removing unnecessary `TRUE' and `FALSE' constants, we obtain:

          (key1 < 'abc') OR (key1 < 'bar')

  4. Combining overlapping intervals into one yields the final
     condition to be used for the range scan:

          (key1 < 'bar')

In general (and as demonstrated by the preceding example), the
condition used for a range scan is less restrictive than the `WHERE'
clause. MySQL performs an additional check to filter out rows that
satisfy the range condition but not the full `WHERE' clause.

The range condition extraction algorithm can handle nested `AND'/`OR'
constructs of arbitrary depth, and its output does not depend on the
order in which conditions appear in `WHERE' clause.

Currently, MySQL does not support merging multiple ranges for the
`range' access method for spatial indexes. To work around this
limitation, you can use a `UNION' with identical `SELECT' statements,
except that you put each spatial predicate in a different `SELECT'.


File: manual.info,  Node: range-access-multi-part,  Prev: range-access-single-part,  Up: range-optimization

7.2.5.2 The Range Access Method for Multiple-Part Indexes
.........................................................

Range conditions on a multiple-part index are an extension of range
conditions for a single-part index. A range condition on a
multiple-part index restricts index rows to lie within one or several
key tuple intervals. Key tuple intervals are defined over a set of key
tuples, using ordering from the index.

For example, consider a multiple-part index defined as `key1(KEY_PART1,
KEY_PART2, KEY_PART3)', and the following set of key tuples listed in
key order:

     KEY_PART1  KEY_PART2  KEY_PART3
       NULL       1          'abc'
       NULL       1          'xyz'
       NULL       2          'foo'
        1         1          'abc'
        1         1          'xyz'
        1         2          'abc'
        2         1          'aaa'

The condition `KEY_PART1 = 1' defines this interval:

     (1,-inf,-inf) <= (KEY_PART1,KEY_PART2,KEY_PART3) < (1,+inf,+inf)

The interval covers the 4th, 5th, and 6th tuples in the preceding data
set and can be used by the range access method.

By contrast, the condition `KEY_PART3 = 'abc'' does not define a single
interval and cannot be used by the range access method.

The following descriptions indicate how range conditions work for
multiple-part indexes in greater detail.

   * For `HASH' indexes, each interval containing identical values can
     be used. This means that the interval can be produced only for
     conditions in the following form:

              KEY_PART1 CMP CONST1
          AND KEY_PART2 CMP CONST2
          AND ...
          AND KEY_PARTN CMP CONSTN;

     Here, CONST1, CONST2, ... are constants, CMP is one of the `=',
     `<=>', or `IS NULL' comparison operators, and the conditions cover
     all index parts. (That is, there are N conditions, one for each
     part of an N-part index.) For example, the following is a range
     condition for a three-part `HASH' index:

          KEY_PART1 = 1 AND KEY_PART2 IS NULL AND KEY_PART3 = 'foo'

     For the definition of what is considered to be a constant, see
     *Note range-access-single-part::.

   * For a `BTREE' index, an interval might be usable for conditions
     combined with `AND', where each condition compares a key part with
     a constant value using `=', `<=>', `IS NULL', `>', `<', `>=', `<=',
     `!=', `<>', `BETWEEN', or `LIKE 'PATTERN'' (where `'PATTERN'' does
     not start with a wildcard). An interval can be used as long as it
     is possible to determine a single key tuple containing all rows
     that match the condition (or two intervals if `<>' or `!=' is
     used). For example, for this condition:

          KEY_PART1 = 'foo' AND KEY_PART2 >= 10 AND KEY_PART3 > 10

     The single interval is:

          ('foo',10,10) < (KEY_PART1,KEY_PART2,KEY_PART3) < ('foo',+inf,+inf)

     It is possible that the created interval contains more rows than
     the initial condition. For example, the preceding interval
     includes the value `('foo', 11, 0)', which does not satisfy the
     original condition.

   * If conditions that cover sets of rows contained within intervals
     are combined with `OR', they form a condition that covers a set of
     rows contained within the union of their intervals. If the
     conditions are combined with `AND', they form a condition that
     covers a set of rows contained within the intersection of their
     intervals. For example, for this condition on a two-part index:

          (KEY_PART1 = 1 AND KEY_PART2 < 2) OR (KEY_PART1 > 5)

     The intervals are:

          (1,-inf) < (KEY_PART1,KEY_PART2) < (1,2)
          (5,-inf) < (KEY_PART1,KEY_PART2)

     In this example, the interval on the first line uses one key part
     for the left bound and two key parts for the right bound. The
     interval on the second line uses only one key part. The `key_len'
     column in the `EXPLAIN' output indicates the maximum length of the
     key prefix used.

     In some cases, `key_len' may indicate that a key part was used,
     but that might be not what you would expect. Suppose that
     KEY_PART1 and KEY_PART2 can be `NULL'. Then the `key_len' column
     displays two key part lengths for the following condition:

          KEY_PART1 >= 1 AND KEY_PART2 < 2

     But, in fact, the condition is converted to this:

          KEY_PART1 >= 1 AND KEY_PART2 IS NOT NULL

*Note range-access-single-part::, describes how optimizations are
performed to combine or eliminate intervals for range conditions on a
single-part index. Analogous steps are performed for range conditions
on multiple-part indexes.


File: manual.info,  Node: index-merge-optimization,  Next: condition-pushdown-optimization,  Prev: range-optimization,  Up: query-speed

7.2.6 Index Merge Optimization
------------------------------

* Menu:

* index-merge-intersection::     The Index Merge Intersection Access Algorithm
* index-merge-union::            The Index Merge Union Access Algorithm
* index-merge-sort-union::       The Index Merge Sort-Union Access Algorithm

The _Index Merge_ method is used to retrieve rows with several `range'
scans and to merge their results into one. The merge can produce unions,
intersections, or unions-of-intersections of its underlying scans. This
access method merges index scans from a single table; it does not merge
scans across multiple tables.

In `EXPLAIN' output, the Index Merge method appears as `index_merge' in
the `type' column. In this case, the `key' column contains a list of
indexes used, and `key_len' contains a list of the longest key parts
for those indexes.

Examples:

     SELECT * FROM TBL_NAME WHERE KEY1 = 10 OR KEY2 = 20;

     SELECT * FROM TBL_NAME
       WHERE (KEY1 = 10 OR KEY2 = 20) AND NON_KEY=30;

     SELECT * FROM t1, t2
       WHERE (t1.KEY1 IN (1,2) OR t1.KEY2 LIKE 'VALUE%')
       AND t2.KEY1=t1.SOME_COL;

     SELECT * FROM t1, t2
       WHERE t1.KEY1=1
       AND (t2.KEY1=t1.SOME_COL OR t2.KEY2=t1.SOME_COL2);

The Index Merge method has several access algorithms (seen in the
`Extra' field of `EXPLAIN' output):

   * `Using intersect(...)'

   * `Using union(...)'

   * `Using sort_union(...)'

The following sections describe these methods in greater detail.

*Note*:

The Index Merge optimization algorithm has the following known
deficiencies:

   * If a range scan is possible on some key, the optimizer will not
     consider using Index Merge Union or Index Merge Sort-Union
     algorithms. For example, consider this query:

          SELECT * FROM t1 WHERE (goodkey1 < 10 OR goodkey2 < 20) AND badkey < 30;

     For this query, two plans are possible:

        * An Index Merge scan using the `(goodkey1 < 10 OR goodkey2 <
          20)' condition.

        * A range scan using the `badkey < 30' condition.

     However, the optimizer considers only the second plan.

   * If your query has a complex `WHERE' clause with deep `AND'/`OR'
     nesting and MySQL doesn't choose the optimal plan, try
     distributing terms using the following identity laws:

          (X AND Y) OR Z = (X OR Z) AND (Y OR Z)
          (X OR Y) AND Z = (X AND Z) OR (Y AND Z)

   * Index Merge is not applicable to fulltext indexes. We plan to
     extend it to cover these in a future MySQL release.

The choice between different possible variants of the Index Merge
access method and other access methods is based on cost estimates of
various available options.


File: manual.info,  Node: index-merge-intersection,  Next: index-merge-union,  Prev: index-merge-optimization,  Up: index-merge-optimization

7.2.6.1 The Index Merge Intersection Access Algorithm
.....................................................

This access algorithm can be employed when a `WHERE' clause was
converted to several range conditions on different keys combined with
`AND', and each condition is one of the following:

   * In this form, where the index has exactly N parts (that is, all
     index parts are covered):

          KEY_PART1=CONST1 AND KEY_PART2=CONST2 ... AND KEY_PARTN=CONSTN

   * Any range condition over a primary key of an `InnoDB' table.

Examples:

     SELECT * FROM INNODB_TABLE WHERE PRIMARY_KEY < 10 AND KEY_COL1=20;

     SELECT * FROM TBL_NAME
       WHERE (KEY1_PART1=1 AND KEY1_PART2=2) AND KEY2=2;

The Index Merge intersection algorithm performs simultaneous scans on
all used indexes and produces the intersection of row sequences that it
receives from the merged index scans.

If all columns used in the query are covered by the used indexes, full
table rows are not retrieved (`EXPLAIN' output contains `Using index'
in `Extra' field in this case). Here is an example of such a query:

     SELECT COUNT(*) FROM t1 WHERE key1=1 AND key2=1;

If the used indexes don't cover all columns used in the query, full
rows are retrieved only when the range conditions for all used keys are
satisfied.

If one of the merged conditions is a condition over a primary key of an
`InnoDB' table, it is not used for row retrieval, but is used to filter
out rows retrieved using other conditions.


File: manual.info,  Node: index-merge-union,  Next: index-merge-sort-union,  Prev: index-merge-intersection,  Up: index-merge-optimization

7.2.6.2 The Index Merge Union Access Algorithm
..............................................

The applicability criteria for this algorithm are similar to those for
the Index Merge method intersection algorithm. The algorithm can be
employed when the table's `WHERE' clause was converted to several range
conditions on different keys combined with `OR', and each condition is
one of the following:

   * In this form, where the index has exactly N parts (that is, all
     index parts are covered):

          KEY_PART1=CONST1 AND KEY_PART2=CONST2 ... AND KEY_PARTN=CONSTN

   * Any range condition over a primary key of an `InnoDB' table.

   * A condition for which the Index Merge method intersection
     algorithm is applicable.

Examples:

     SELECT * FROM t1 WHERE KEY1=1 OR KEY2=2 OR KEY3=3;

     SELECT * FROM INNODB_TABLE WHERE (KEY1=1 AND KEY2=2) OR
       (KEY3='foo' AND KEY4='bar') AND KEY5=5;


File: manual.info,  Node: index-merge-sort-union,  Prev: index-merge-union,  Up: index-merge-optimization

7.2.6.3 The Index Merge Sort-Union Access Algorithm
...................................................

This access algorithm is employed when the `WHERE' clause was converted
to several range conditions combined by `OR', but for which the Index
Merge method union algorithm is not applicable.

Examples:

     SELECT * FROM TBL_NAME WHERE KEY_COL1 < 10 OR KEY_COL2 < 20;

     SELECT * FROM TBL_NAME
       WHERE (KEY_COL1 > 10 OR KEY_COL2 = 20) AND NONKEY_COL=30;

The difference between the sort-union algorithm and the union algorithm
is that the sort-union algorithm must first fetch row IDs for all rows
and sort them before returning any rows.


File: manual.info,  Node: condition-pushdown-optimization,  Next: is-null-optimization,  Prev: index-merge-optimization,  Up: query-speed

7.2.7 Condition Pushdown Optimization
-------------------------------------

This optimization improves the efficiency of a direct comparison
between a non-indexed column and a constant. In such cases, the
condition is `pushed down' to the storage engine for evaluation. In
MySQL 5.1, this optimzation can be used only by the `NDBCLUSTER' storage
engine, but we intend to implement it for additional storage engines in
future versions of MySQL.

For MySQL Cluster this optimization can eliminate the need to send
non-matching rows over the network between the cluster's data nodes and
the MySQL Server that issued the query, and can speed up queries where
it is used by a factor of 5 to 10 times over cases where condition
pushdown could be but is not used.

Suppose that a MySQL Cluster table is defined as follows:

     CREATE TABLE t1 (
         a INT,
         b INT,
         KEY(a)
     ) ENGINE=NDBCLUSTER;

Condition pushdown can be used with a query against this table such as
the query shown here:

     SELECT a,b FROM t1 WHERE b = 10;

This can be seen in the output of `EXPLAIN SELECT':

     mysql> EXPLAIN SELECT a,b FROM t1 WHERE b = 10\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: t1
              type: ALL
     possible_keys: NULL
               key: NULL
           key_len: NULL
               ref: NULL
              rows: 10
             Extra: Using where with pushed condition

However, condition pushdown _cannot_ be used with either of these two
queries:

     SELECT a,b FROM t1 WHERE a = 10;
     SELECT a,b FROM t1 WHERE b + 1 = 10;

With regard to the first of these two queries, condition pushdown is
not applicable because an index exists on column `a'. (An index access
method would be more efficient and so would be chosen in preference to
condition pushdown.) In the case of the second query, condition pushdown
cannot be employed because the comparison involving the non-indexed
column `b' is indirect. (However, condition pushdown could be applied
if you were to reduce `b + 1 = 10' to `b = 9' in the `WHERE' clause.)

Condition pushdown may also be employed when an indexed column is
compared with a constant using a `>' or `<' operator:

     mysql> EXPLAIN SELECT a,b FROM t1 WHERE a<2\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: t1
              type: range
     possible_keys: a
               key: a
           key_len: 5
               ref: NULL
              rows: 2
             Extra: Using where with pushed condition

Other comparisons which are supported for condition pushdown include
the following:

   * `COLUMN [NOT] LIKE PATTERN'

     PATTERN must be a string literal containing the pattern to be
     matched; for syntax, see *Note string-comparison-functions::.

   * `COLUMN IS [NOT] NULL'

   * `COLUMN IN (VALUE_LIST)'

     Each item in the VALUE_LIST must be a constant, literal value.

   * `COLUMN BETWEEN CONSTANT1 AND CONSTANT2'

     CONSTANT1 and CONSTANT2 must each be a constant, literal value.

In all of the cases in the preceding list, it is possible for the
condition to be converted into the form of one or more direct
comparisons between a column and a constant.

Condition pushdown capability is not used by default. To enable it, you
can start `mysqld' with the `--engine-condition-pushdown' option, or
you can execute either of the following statements at runtime:

     SET engine_condition_pushdown=ON;

     SET engine_condition_pushdown=1;

Limitations

Condition pushdown is subject to the following limitations:

   * In MySQL 5.1, condition pushdown is supported by the `NDBCLUSTER'
     storage engine only.

   * Columns may be compared with constants only; however, this
     includes expressions which evaluate to constant values.

   * Columns used in comparisons cannot be of any of the `BLOB' or
     `TEXT' types.

   * A string value to be compared with a column must use the same
     collation as the column.

   * Joins are not directly supported; conditions involving multiple
     tables are pushed separately where possible.  Use `EXPLAIN
     EXTENDED' to determine which conditions are actually pushed down.


File: manual.info,  Node: is-null-optimization,  Next: left-join-optimization,  Prev: condition-pushdown-optimization,  Up: query-speed

7.2.8 `IS NULL' Optimization
----------------------------

MySQL can perform the same optimization on COL_NAME `IS NULL' that it
can use for COL_NAME `=' CONSTANT_VALUE. For example, MySQL can use
indexes and ranges to search for `NULL' with `IS NULL'.

Examples:

     SELECT * FROM TBL_NAME WHERE KEY_COL IS NULL;

     SELECT * FROM TBL_NAME WHERE KEY_COL <=> NULL;

     SELECT * FROM TBL_NAME
       WHERE KEY_COL=CONST1 OR KEY_COL=CONST2 OR KEY_COL IS NULL;

If a `WHERE' clause includes a COL_NAME `IS NULL' condition for a
column that is declared as `NOT NULL', that expression is optimized
away.  This optimization does not occur in cases when the column might
produce `NULL' anyway; for example, if it comes from a table on the
right side of a `LEFT JOIN'.

MySQL can also optimize the combination `COL_NAME = EXPR OR COL_NAME IS
NULL', a form that is common in resolved subqueries.  `EXPLAIN' shows
`ref_or_null' when this optimization is used.

This optimization can handle one `IS NULL' for any key part.

Some examples of queries that are optimized, assuming that there is an
index on columns `a' and `b' of table `t2':

     SELECT * FROM t1 WHERE t1.a=EXPR OR t1.a IS NULL;

     SELECT * FROM t1, t2 WHERE t1.a=t2.a OR t2.a IS NULL;

     SELECT * FROM t1, t2
       WHERE (t1.a=t2.a OR t2.a IS NULL) AND t2.b=t1.b;

     SELECT * FROM t1, t2
       WHERE t1.a=t2.a AND (t2.b=t1.b OR t2.b IS NULL);

     SELECT * FROM t1, t2
       WHERE (t1.a=t2.a AND t2.a IS NULL AND ...)
       OR (t1.a=t2.a AND t2.a IS NULL AND ...);

`ref_or_null' works by first doing a read on the reference key, and
then a separate search for rows with a `NULL' key value.

Note that the optimization can handle only one `IS NULL' level. In the
following query, MySQL uses key lookups only on the expression
`(t1.a=t2.a AND t2.a IS NULL)' and is not able to use the key part on
`b':

     SELECT * FROM t1, t2
       WHERE (t1.a=t2.a AND t2.a IS NULL)
       OR (t1.b=t2.b AND t2.b IS NULL);


File: manual.info,  Node: left-join-optimization,  Next: nested-joins,  Prev: is-null-optimization,  Up: query-speed

7.2.9 `LEFT JOIN' and `RIGHT JOIN' Optimization
-----------------------------------------------

MySQL implements an `A LEFT JOIN B join_condition' as follows:

   * Table B is set to depend on table A and all tables on which A
     depends.

   * Table A is set to depend on all tables (except B) that are used in
     the `LEFT JOIN' condition.

   * The `LEFT JOIN' condition is used to decide how to retrieve rows
     from table B. (In other words, any condition in the `WHERE' clause
     is not used.)

   * All standard join optimizations are performed, with the exception
     that a table is always read after all tables on which it depends.
     If there is a circular dependence, MySQL issues an error.

   * All standard `WHERE' optimizations are performed.

   * If there is a row in A that matches the `WHERE' clause, but there
     is no row in B that matches the `ON' condition, an extra B row is
     generated with all columns set to `NULL'.

   * If you use `LEFT JOIN' to find rows that do not exist in some
     table and you have the following test: `COL_NAME IS NULL' in the
     `WHERE' part, where COL_NAME is a column that is declared as `NOT
     NULL', MySQL stops searching for more rows (for a particular key
     combination) after it has found one row that matches the `LEFT
     JOIN' condition.

The implementation of `RIGHT JOIN' is analogous to that of `LEFT JOIN'
with the roles of the tables reversed.

The join optimizer calculates the order in which tables should be
joined. The table read order forced by `LEFT JOIN' or `STRAIGHT_JOIN'
helps the join optimizer do its work much more quickly, because there
are fewer table permutations to check. Note that this means that if you
do a query of the following type, MySQL does a full scan on `b' because
the `LEFT JOIN' forces it to be read before `d':

     SELECT *
       FROM a JOIN b LEFT JOIN c ON (c.key=a.key)
       LEFT JOIN d ON (d.key=a.key)
       WHERE b.key=d.key;

The fix in this case is reverse the order in which `a' and `b' are
listed in the `FROM' clause:

     SELECT *
       FROM b JOIN a LEFT JOIN c ON (c.key=a.key)
       LEFT JOIN d ON (d.key=a.key)
       WHERE b.key=d.key;

For a `LEFT JOIN', if the `WHERE' condition is always false for the
generated `NULL' row, the `LEFT JOIN' is changed to a normal join. For
example, the `WHERE' clause would be false in the following query if
`t2.column1' were `NULL':

     SELECT * FROM t1 LEFT JOIN t2 ON (column1) WHERE t2.column2=5;

Therefore, it is safe to convert the query to a normal join:

     SELECT * FROM t1, t2 WHERE t2.column2=5 AND t1.column1=t2.column1;

This can be made faster because MySQL can use table `t2' before table
`t1' if doing so would result in a better query plan. To provide a hint
about the table join order, use `STRAIGHT_JOIN'. (See *Note select::.)


File: manual.info,  Node: nested-joins,  Next: outer-join-simplification,  Prev: left-join-optimization,  Up: query-speed

7.2.10 Nested Join Optimization
-------------------------------

The syntax for expressing joins allows nested joins. The following
discussion refers to the join syntax described in *Note join::.

The syntax of TABLE_FACTOR is extended in comparison with the SQL
Standard. The latter accepts only TABLE_REFERENCE, not a list of them
inside a pair of parentheses. This is a conservative extension if we
consider each comma in a list of TABLE_REFERENCE items as equivalent to
an inner join. For example:

     SELECT * FROM t1 LEFT JOIN (t2, t3, t4)
                      ON (t2.a=t1.a AND t3.b=t1.b AND t4.c=t1.c)

is equivalent to:

     SELECT * FROM t1 LEFT JOIN (t2 CROSS JOIN t3 CROSS JOIN t4)
                      ON (t2.a=t1.a AND t3.b=t1.b AND t4.c=t1.c)

In MySQL, `CROSS JOIN' is a syntactic equivalent to `INNER JOIN' (they
can replace each other). In standard SQL, they are not equivalent.
`INNER JOIN' is used with an `ON' clause; `CROSS JOIN' is used
otherwise.

In general, parentheses can be ignored in join expressions containing
only inner join operations. After removing parentheses and grouping
operations to the left, the join expression:

     t1 LEFT JOIN (t2 LEFT JOIN t3 ON t2.b=t3.b OR t2.b IS NULL)
        ON t1.a=t2.a

transforms into the expression:

     (t1 LEFT JOIN t2 ON t1.a=t2.a) LEFT JOIN t3
         ON t2.b=t3.b OR t2.b IS NULL

Yet, the two expressions are not equivalent. To see this, suppose that
the tables `t1', `t2', and `t3' have the following state:

   * Table `t1' contains rows `(1)', `(2)'

   * Table `t2' contains row `(1,101)'

   * Table `t3' contains row `(101)'

In this case, the first expression returns a result set including the
rows `(1,1,101,101)', `(2,NULL,NULL,NULL)', whereas the second
expression returns the rows `(1,1,101,101)', `(2,NULL,NULL,101)':

     mysql> SELECT *
         -> FROM t1
         ->      LEFT JOIN
         ->      (t2 LEFT JOIN t3 ON t2.b=t3.b OR t2.b IS NULL)
         ->      ON t1.a=t2.a;
     +------+------+------+------+
     | a    | a    | b    | b    |
     +------+------+------+------+
     |    1 |    1 |  101 |  101 |
     |    2 | NULL | NULL | NULL |
     +------+------+------+------+

     mysql> SELECT *
         -> FROM (t1 LEFT JOIN t2 ON t1.a=t2.a)
         ->      LEFT JOIN t3
         ->      ON t2.b=t3.b OR t2.b IS NULL;
     +------+------+------+------+
     | a    | a    | b    | b    |
     +------+------+------+------+
     |    1 |    1 |  101 |  101 |
     |    2 | NULL | NULL |  101 |
     +------+------+------+------+

In the following example, an outer join operation is used together with
an inner join operation:

     t1 LEFT JOIN (t2, t3) ON t1.a=t2.a

That expression cannot be transformed into the following expression:

     t1 LEFT JOIN t2 ON t1.a=t2.a, t3.

For the given table states, the two expressions return different sets
of rows:

     mysql> SELECT *
         -> FROM t1 LEFT JOIN (t2, t3) ON t1.a=t2.a;
     +------+------+------+------+
     | a    | a    | b    | b    |
     +------+------+------+------+
     |    1 |    1 |  101 |  101 |
     |    2 | NULL | NULL | NULL |
     +------+------+------+------+

     mysql> SELECT *
         -> FROM t1 LEFT JOIN t2 ON t1.a=t2.a, t3;
     +------+------+------+------+
     | a    | a    | b    | b    |
     +------+------+------+------+
     |    1 |    1 |  101 |  101 |
     |    2 | NULL | NULL |  101 |
     +------+------+------+------+

Therefore, if we omit parentheses in a join expression with outer join
operators, we might change the result set for the original expression.

More exactly, we cannot ignore parentheses in the right operand of the
left outer join operation and in the left operand of a right join
operation. In other words, we cannot ignore parentheses for the inner
table expressions of outer join operations. Parentheses for the other
operand (operand for the outer table) can be ignored.

The following expression:

     (t1,t2) LEFT JOIN t3 ON P(t2.b,t3.b)

is equivalent to this expression:

     t1, t2 LEFT JOIN t3 ON P(t2.b,t3.b)

for any tables `t1,t2,t3' and any condition `P' over attributes `t2.b'
and `t3.b'.

Whenever the order of execution of the join operations in a join
expression (JOIN_TABLE) is not from left to right, we talk about nested
joins. Consider the following queries:

     SELECT * FROM t1 LEFT JOIN (t2 LEFT JOIN t3 ON t2.b=t3.b) ON t1.a=t2.a
       WHERE t1.a > 1

     SELECT * FROM t1 LEFT JOIN (t2, t3) ON t1.a=t2.a
       WHERE (t2.b=t3.b OR t2.b IS NULL) AND t1.a > 1

Those queries are considered to contain these nested joins:

     t2 LEFT JOIN t3 ON t2.b=t3.b
     t2, t3

The nested join is formed in the first query with a left join
operation, whereas in the second query it is formed with an inner join
operation.

In the first query, the parentheses can be omitted: The grammatical
structure of the join expression will dictate the same order of
execution for join operations. For the second query, the parentheses
cannot be omitted, although the join expression here can be interpreted
unambiguously without them.  (In our extended syntax the parentheses in
`(t2, t3)' of the second query are required, although theoretically the
query could be parsed without them: We still would have unambiguous
syntactical structure for the query because `LEFT JOIN' and `ON' would
play the role of the left and right delimiters for the expression
`(t2,t3)'.)

The preceding examples demonstrate these points:

   * For join expressions involving only inner joins (and not outer
     joins), parentheses can be removed. You can remove parentheses and
     evaluate left to right (or, in fact, you can evaluate the tables
     in any order).

   * The same is not true, in general, for outer joins or for outer
     joins mixed with inner joins. Removal of parentheses may change
     the result.

Queries with nested outer joins are executed in the same pipeline
manner as queries with inner joins. More exactly, a variation of the
nested-loop join algorithm is exploited. Recall by what algorithmic
schema the nested-loop join executes a query. Suppose that we have a
join query over 3 tables `T1,T2,T3' of the form:

     SELECT * FROM T1 INNER JOIN T2 ON P1(T1,T2)
                      INNER JOIN T3 ON P2(T2,T3)
       WHERE P(T1,T2,T3).

Here, `P1(T1,T2)' and `P2(T3,T3)' are some join conditions (on
expressions), whereas `P(t1,t2,t3)' is a condition over columns of
tables `T1,T2,T3'.

The nested-loop join algorithm would execute this query in the
following manner:

     FOR each row t1 in T1 {
       FOR each row t2 in T2 such that P1(t1,t2) {
         FOR each row t3 in T3 such that P2(t2,t3) {
           IF P(t1,t2,t3) {
              t:=t1||t2||t3; OUTPUT t;
           }
         }
       }
     }

The notation `t1||t2||t3' means `a row constructed by concatenating the
columns of rows `t1', `t2', and `t3'.' In some of the following
examples, `NULL' where a row name appears means that `NULL' is used for
each column of that row. For example, `t1||t2||NULL' means `a row
constructed by concatenating the columns of rows `t1' and `t2', and
`NULL' for each column of `t3'.'

Now let's consider a query with nested outer joins:

     SELECT * FROM T1 LEFT JOIN
                   (T2 LEFT JOIN T3 ON P2(T2,T3))
                   ON P1(T1,T2)
       WHERE P(T1,T2,T3).

For this query, we modify the nested-loop pattern to get:

     FOR each row t1 in T1 {
       BOOL f1:=FALSE;
       FOR each row t2 in T2 such that P1(t1,t2) {
         BOOL f2:=FALSE;
         FOR each row t3 in T3 such that P2(t2,t3) {
           IF P(t1,t2,t3) {
             t:=t1||t2||t3; OUTPUT t;
           }
           f2=TRUE;
           f1=TRUE;
         }
         IF (!f2) {
           IF P(t1,t2,NULL) {
             t:=t1||t2||NULL; OUTPUT t;
           }
           f1=TRUE;
         }
       }
       IF (!f1) {
         IF P(t1,NULL,NULL) {
           t:=t1||NULL||NULL; OUTPUT t;
         }
       }
     }

In general, for any nested loop for the first inner table in an outer
join operation, a flag is introduced that is turned off before the loop
and is checked after the loop. The flag is turned on when for the
current row from the outer table a match from the table representing
the inner operand is found. If at the end of the loop cycle the flag is
still off, no match has been found for the current row of the outer
table. In this case, the row is complemented by `NULL' values for the
columns of the inner tables. The result row is passed to the final
check for the output or into the next nested loop, but only if the row
satisfies the join condition of all embedded outer joins.

In our example, the outer join table expressed by the following
expression is embedded:

     (T2 LEFT JOIN T3 ON P2(T2,T3))

Note that for the query with inner joins, the optimizer could choose a
different order of nested loops, such as this one:

     FOR each row t3 in T3 {
       FOR each row t2 in T2 such that P2(t2,t3) {
         FOR each row t1 in T1 such that P1(t1,t2) {
           IF P(t1,t2,t3) {
              t:=t1||t2||t3; OUTPUT t;
           }
         }
       }
     }

For the queries with outer joins, the optimizer can choose only such an
order where loops for outer tables precede loops for inner tables.
Thus, for our query with outer joins, only one nesting order is
possible. For the following query, the optimizer will evaluate two
different nestings:

     SELECT * T1 LEFT JOIN (T2,T3) ON P1(T1,T2) AND P2(T1,T3)
       WHERE P(T1,T2,T3)

The nestings are these:

     FOR each row t1 in T1 {
       BOOL f1:=FALSE;
       FOR each row t2 in T2 such that P1(t1,t2) {
         FOR each row t3 in T3 such that P2(t1,t3) {
           IF P(t1,t2,t3) {
             t:=t1||t2||t3; OUTPUT t;
           }
           f1:=TRUE
         }
       }
       IF (!f1) {
         IF P(t1,NULL,NULL) {
           t:=t1||NULL||NULL; OUTPUT t;
         }
       }
     }

and:

     FOR each row t1 in T1 {
       BOOL f1:=FALSE;
       FOR each row t3 in T3 such that P2(t1,t3) {
         FOR each row t2 in T2 such that P1(t1,t2) {
           IF P(t1,t2,t3) {
             t:=t1||t2||t3; OUTPUT t;
           }
           f1:=TRUE
         }
       }
       IF (!f1) {
         IF P(t1,NULL,NULL) {
           t:=t1||NULL||NULL; OUTPUT t;
         }
       }
     }

In both nestings, `T1' must be processed in the outer loop because it
is used in an outer join.  `T2' and `T3' are used in an inner join, so
that join must be processed in the inner loop.  However, because the
join is an inner join, `T2' and `T3' can be processed in either order.

When discussing the nested-loop algorithm for inner joins, we omitted
some details whose impact on the performance of query execution may be
huge. We did not mention so-called `pushed-down' conditions. Suppose
that our `WHERE' condition `P(T1,T2,T3)' can be represented by a
conjunctive formula:

     P(T1,T2,T2) = C1(T1) AND C2(T2) AND C3(T3).

In this case, MySQL actually uses the following nested-loop schema for
the execution of the query with inner joins:

     FOR each row t1 in T1 such that C1(t1) {
       FOR each row t2 in T2 such that P1(t1,t2) AND C2(t2)  {
         FOR each row t3 in T3 such that P2(t2,t3) AND C3(t3) {
           IF P(t1,t2,t3) {
              t:=t1||t2||t3; OUTPUT t;
           }
         }
       }
     }

You see that each of the conjuncts `C1(T1)', `C2(T2)', `C3(T3)' are
pushed out of the most inner loop to the most outer loop where it can
be evaluated. If `C1(T1)' is a very restrictive condition, this
condition pushdown may greatly reduce the number of rows from table
`T1' passed to the inner loops. As a result, the execution time for the
query may improve immensely.

For a query with outer joins, the `WHERE' condition is to be checked
only after it has been found that the current row from the outer table
has a match in the inner tables. Thus, the optimization of pushing
conditions out of the inner nested loops cannot be applied directly to
queries with outer joins. Here we have to introduce conditional
pushed-down predicates guarded by the flags that are turned on when a
match has been encountered.

For our example with outer joins with:

     P(T1,T2,T3)=C1(T1) AND C(T2) AND C3(T3)

the nested-loop schema using guarded pushed-down conditions looks like
this:

     FOR each row t1 in T1 such that C1(t1) {
       BOOL f1:=FALSE;
       FOR each row t2 in T2
           such that P1(t1,t2) AND (f1?C2(t2):TRUE) {
         BOOL f2:=FALSE;
         FOR each row t3 in T3
             such that P2(t2,t3) AND (f1&&f2?C3(t3):TRUE) {
           IF (f1&&f2?TRUE:(C2(t2) AND C3(t3))) {
             t:=t1||t2||t3; OUTPUT t;
           }
           f2=TRUE;
           f1=TRUE;
         }
         IF (!f2) {
           IF (f1?TRUE:C2(t2) && P(t1,t2,NULL)) {
             t:=t1||t2||NULL; OUTPUT t;
           }
           f1=TRUE;
         }
       }
       IF (!f1 && P(t1,NULL,NULL)) {
           t:=t1||NULL||NULL; OUTPUT t;
       }
     }

In general, pushed-down predicates can be extracted from join
conditions such as `P1(T1,T2)' and `P(T2,T3)'. In this case, a
pushed-down predicate is guarded also by a flag that prevents checking
the predicate for the `NULL'-complemented row generated by the
corresponding outer join operation.

Note that access by key from one inner table to another in the same
nested join is prohibited if it is induced by a predicate from the
`WHERE' condition. (We could use conditional key access in this case,
but this technique is not employed yet in MySQL 5.1.)


File: manual.info,  Node: outer-join-simplification,  Next: order-by-optimization,  Prev: nested-joins,  Up: query-speed

7.2.11 Outer Join Simplification
--------------------------------

Table expressions in the `FROM' clause of a query are simplified in
many cases.

At the parser stage, queries with right outer joins operations are
converted to equivalent queries containing only left join operations.
In the general case, the conversion is performed according to the
following rule:

     (T1, ...) RIGHT JOIN (T2,...) ON P(T1,...,T2,...) =
     (T2, ...) LEFT JOIN (T1,...) ON P(T1,...,T2,...)

All inner join expressions of the form `T1 INNER JOIN T2 ON P(T1,T2)'
are replaced by the list `T1,T2', `P(T1,T2)' being joined as a conjunct
to the `WHERE' condition (or to the join condition of the embedding
join, if there is any).

When the optimizer evaluates plans for join queries with outer join
operation, it takes into consideration only the plans where, for each
such operation, the outer tables are accessed before the inner tables.
The optimizer options are limited because only such plans enables us to
execute queries with outer joins operations by the nested loop schema.

Suppose that we have a query of the form:

     SELECT * T1 LEFT JOIN T2 ON P1(T1,T2)
       WHERE P(T1,T2) AND R(T2)

with `R(T2)' narrowing greatly the number of matching rows from table
`T2'. If we executed the query as it is, the optimizer would have no
other choice besides to access table `T1' before table `T2' that may
lead to a very inefficient execution plan.

Fortunately, MySQL converts such a query into a query without an outer
join operation if the `WHERE' condition is null-rejected. A condition
is called null-rejected for an outer join operation if it evaluates to
`FALSE' or to `UNKNOWN' for any `NULL'-complemented row built for the
operation.

Thus, for this outer join:

     T1 LEFT JOIN T2 ON T1.A=T2.A

Conditions such as these are null-rejected:

     T2.B IS NOT NULL,
     T2.B > 3,
     T2.C <= T1.C,
     T2.B < 2 OR T2.C > 1

Conditions such as these are not null-rejected:

     T2.B IS NULL,
     T1.B < 3 OR T2.B IS NOT NULL,
     T1.B < 3 OR T2.B > 3

The general rules for checking whether a condition is null-rejected for
an outer join operation are simple. A condition is null-rejected in the
following cases:

   * If it is of the form `A IS NOT NULL', where `A' is an attribute of
     any of the inner tables

   * If it is a predicate containing a reference to an inner table that
     evaluates to `UNKNOWN' when one of its arguments is `NULL'

   * If it is a conjunction containing a null-rejected condition as a
     conjunct

   * If it is a disjunction of null-rejected conditions

A condition can be null-rejected for one outer join operation in a
query and not null-rejected for another. In the query:

     SELECT * FROM T1 LEFT JOIN T2 ON T2.A=T1.A
                      LEFT JOIN T3 ON T3.B=T1.B
       WHERE T3.C > 0

the `WHERE' condition is null-rejected for the second outer join
operation but is not null-rejected for the first one.

If the `WHERE' condition is null-rejected for an outer join operation
in a query, the outer join operation is replaced by an inner join
operation.

For example, the preceding query is replaced with the query:

     SELECT * FROM T1 LEFT JOIN T2 ON T2.A=T1.A
                      INNER JOIN T3 ON T3.B=T1.B
       WHERE T3.C > 0

For the original query, the optimizer would evaluate plans compatible
with only one access order `T1,T2,T3'. For the replacing query, it
additionally considers the access sequence `T3,T1,T2'.

A conversion of one outer join operation may trigger a conversion of
another. Thus, the query:

     SELECT * FROM T1 LEFT JOIN T2 ON T2.A=T1.A
                      LEFT JOIN T3 ON T3.B=T2.B
       WHERE T3.C > 0

will be first converted to the query:

     SELECT * FROM T1 LEFT JOIN T2 ON T2.A=T1.A
                      INNER JOIN T3 ON T3.B=T2.B
       WHERE T3.C > 0

which is equivalent to the query:

     SELECT * FROM (T1 LEFT JOIN T2 ON T2.A=T1.A), T3
       WHERE T3.C > 0 AND T3.B=T2.B

Now the remaining outer join operation can be replaced by an inner
join, too, because the condition `T3.B=T2.B' is null-rejected and we
get a query without outer joins at all:

     SELECT * FROM (T1 INNER JOIN T2 ON T2.A=T1.A), T3
       WHERE T3.C > 0 AND T3.B=T2.B

Sometimes we succeed in replacing an embedded outer join operation, but
cannot convert the embedding outer join. The following query:

     SELECT * FROM T1 LEFT JOIN
                   (T2 LEFT JOIN T3 ON T3.B=T2.B)
                   ON T2.A=T1.A
       WHERE T3.C > 0

is converted to:

     SELECT * FROM T1 LEFT JOIN
                   (T2 INNER JOIN T3 ON T3.B=T2.B)
                   ON T2.A=T1.A
       WHERE T3.C > 0,

That can be rewritten only to the form still containing the embedding
outer join operation:

     SELECT * FROM T1 LEFT JOIN
                   (T2,T3)
                   ON (T2.A=T1.A AND T3.B=T2.B)
       WHERE T3.C > 0.

When trying to convert an embedded outer join operation in a query, we
must take into account the join condition for the embedding outer join
together with the `WHERE' condition. In the query:

     SELECT * FROM T1 LEFT JOIN
                   (T2 LEFT JOIN T3 ON T3.B=T2.B)
                   ON T2.A=T1.A AND T3.C=T1.C
       WHERE T3.D > 0 OR T1.D > 0

the `WHERE' condition is not null-rejected for the embedded outer join,
but the join condition of the embedding outer join `T2.A=T1.A AND
T3.C=T1.C' is null-rejected. So the query can be converted to:

     SELECT * FROM T1 LEFT JOIN
                   (T2, T3)
                   ON T2.A=T1.A AND T3.C=T1.C AND T3.B=T2.B
       WHERE T3.D > 0 OR T1.D > 0


File: manual.info,  Node: order-by-optimization,  Next: group-by-optimization,  Prev: outer-join-simplification,  Up: query-speed

7.2.12 `ORDER BY' Optimization
------------------------------

In some cases, MySQL can use an index to satisfy an `ORDER BY' clause
without doing any extra sorting.

The index can also be used even if the `ORDER BY' does not match the
index exactly, as long as all of the unused portions of the index and
all the extra `ORDER BY' columns are constants in the `WHERE' clause.
The following queries use the index to resolve the `ORDER BY' part:

     SELECT * FROM t1
       ORDER BY KEY_PART1,KEY_PART2,... ;

     SELECT * FROM t1
       WHERE KEY_PART1=CONSTANT
       ORDER BY KEY_PART2;

     SELECT * FROM t1
       ORDER BY KEY_PART1 DESC, KEY_PART2 DESC;

     SELECT * FROM t1
       WHERE KEY_PART1=1
       ORDER BY KEY_PART1 DESC, KEY_PART2 DESC;

In some cases, MySQL _cannot_ use indexes to resolve the `ORDER BY',
although it still uses indexes to find the rows that match the `WHERE'
clause. These cases include the following:

   * You use `ORDER BY' on different keys:

          SELECT * FROM t1 ORDER BY KEY1, KEY2;

   * You use `ORDER BY' on non-consecutive parts of a key:

          SELECT * FROM t1 WHERE KEY2=CONSTANT ORDER BY KEY_PART2;

   * You mix `ASC' and `DESC':

          SELECT * FROM t1 ORDER BY KEY_PART1 DESC, KEY_PART2 ASC;

   * The key used to fetch the rows is not the same as the one used in
     the `ORDER BY':

          SELECT * FROM t1 WHERE KEY2=CONSTANT ORDER BY KEY1;

   * You use `ORDER BY' with an expression that includes terms other
     than the key column name:

          SELECT * FROM t1 ORDER BY ABS(KEY);
          SELECT * FROM t1 ORDER BY -KEY;

   * You are joining many tables, and the columns in the `ORDER BY' are
     not all from the first non-constant table that is used to retrieve
     rows. (This is the first table in the `EXPLAIN' output that does
     not have a `const' join type.)

   * You have different `ORDER BY' and `GROUP BY' expressions.

   * The type of table index used does not store rows in order.  For
     example, this is true for a `HASH' index in a `MEMORY' table.

Availability of an index for sorting may be affected by the use of
column aliases. Suppose that the column `t1.a' is indexed. In this
statement, the name of the column in the select list is `a'. It refers
to `t1.a', so for the reference to `a' in the `ORDER BY', the index can
be used:

     SELECT a FROM t1 ORDER BY a;

In this statement, the name of the column in the select list is also
`a', but it is the alias name. It refers to `ABS(a)', so for the
reference to `a' in the `ORDER BY', the index cannot be used:

     SELECT ABS(a) AS a FROM t1 ORDER BY a;

In the following statement, the `ORDER BY' refers to a name that is not
the name of a column in the select list. But there is a column in `t1'
named `a', so the `ORDER BY' uses that, and the index can be used. (The
resulting sort order may be completely different from the order for
`ABS(a)', of course.)

     SELECT ABS(a) AS b FROM t1 ORDER BY a;

By default, MySQL sorts all `GROUP BY COL1, COL2, ...' queries as if you
specified `ORDER BY COL1, COL2, ...' in the query as well. If you
include an `ORDER BY' clause explicitly that contains the same column
list, MySQL optimizes it away without any speed penalty, although the
sorting still occurs. If a query includes `GROUP BY' but you want to
avoid the overhead of sorting the result, you can suppress sorting by
specifying `ORDER BY NULL'.  For example:

     INSERT INTO foo
     SELECT a, COUNT(*) FROM bar GROUP BY a ORDER BY NULL;

With `EXPLAIN SELECT ... ORDER BY', you can check whether MySQL can use
indexes to resolve the query. It cannot if you see `Using filesort' in
the `Extra' column. See *Note using-explain::.

MySQL has two `filesort' algorithms for sorting and retrieving results.
The original method uses only the `ORDER BY' columns. The modified
method uses not just the `ORDER BY' columns, but all the columns used
in the query.

The optimizer selects which `filesort' algorithm to use. It normally
uses the modified algorithm except when `BLOB' or `TEXT' columns are
involved, in which case it uses the original algorithm.

The original `filesort' algorithm works as follows:

  1. Read all rows according to key or by table scanning. Rows that do
     not match the `WHERE' clause are skipped.

  2. For each row, store a pair of values in a buffer (the sort key and
     the row pointer). The size of the buffer is the value of the
     `sort_buffer_size' system variable.

  3. When the buffer gets full, run a qsort (quicksort) on it and store
     the result in a temporary file. Save a pointer to the sorted
     block. (If all pairs fit into the sort buffer, no temporary file
     is created.)

  4. Repeat the preceding steps until all rows have been read.

  5. Do a multi-merge of up to `MERGEBUFF' (7) regions to one block in
     another temporary file. Repeat until all blocks from the first
     file are in the second file.

  6. Repeat the following until there are fewer than `MERGEBUFF2' (15)
     blocks left.

  7. On the last multi-merge, only the pointer to the row (the last
     part of the sort key) is written to a result file.

  8. Read the rows in sorted order by using the row pointers in the
     result file. To optimize this, we read in a big block of row
     pointers, sort them, and use them to read the rows in sorted order
     into a row buffer. The size of the buffer is the value of the
     `read_rnd_buffer_size' system variable. The code for this step is
     in the `sql/records.cc' source file.

One problem with this approach is that it reads rows twice: One time
when evaluating the `WHERE' clause, and again after sorting the pair
values. And even if the rows were accessed successively the first time
(for example, if a table scan is done), the second time they are
accessed randomly. (The sort keys are ordered, but the row positions
are not.)

The modified `filesort' algorithm incorporates an optimization such
that it records not only the sort key value and row position, but also
the columns required for the query.  This avoids reading the rows
twice. The modified `filesort' algorithm works like this:

  1. Read the rows that match the `WHERE' clause.

  2. For each row, record a tuple of values consisting of the sort key
     value and row position, and also the columns required for the
     query.

  3. Sort the tuples by sort key value

  4. Retrieve the rows in sorted order, but read the required columns
     directly from the sorted tuples rather than by accessing the table
     a second time.

Using the modified `filesort' algorithm, the tuples are longer than the
pairs used in the original method, and fewer of them fit in the sort
buffer (the size of which is given by `sort_buffer_size'). As a result,
it is possible for the extra I/O to make the modified approach slower,
not faster. To avoid a slowdown, the optimization is used only if the
total size of the extra columns in the sort tuple does not exceed the
value of the `max_length_for_sort_data' system variable. (A symptom of
setting the value of this variable too high is that you should see high
disk activity and low CPU activity.)

For slow queries for which `filesort' is not used, you might try
lowering `max_length_for_sort_data' to a value that is appropriate to
trigger a `filesort'.

If you want to increase `ORDER BY' speed, check whether you can get
MySQL to use indexes rather than an extra sorting phase. If this is not
possible, you can try the following strategies:

   * Increase the size of the `sort_buffer_size' variable.

   * Increase the size of the `read_rnd_buffer_size' variable.

   * Use less RAM per row by declaring columns only as large as they
     need to be to hold the values stored in them. For example,
     `CHAR(16)' is better than `CHAR(200)' if values never exceed 16
     characters.

   * Change `tmpdir' to point to a dedicated filesystem with large
     amounts of free space. Also, this option accepts several paths
     that are used in round-robin fashion, so you can use this feature
     to spread the load across several directories. Paths should be
     separated by colon characters (``:'') on Unix and semicolon
     characters (``;'') on Windows, NetWare, and OS/2. The paths should
     be for directories in filesystems that are located on different
     _physical_ disks, not different partitions on the same disk.


File: manual.info,  Node: group-by-optimization,  Next: distinct-optimization,  Prev: order-by-optimization,  Up: query-speed

7.2.13 `GROUP BY' Optimization
------------------------------

* Menu:

* loose-index-scan::             Loose index scan
* tight-index-scan::             Tight index scan

The most general way to satisfy a `GROUP BY' clause is to scan the
whole table and create a new temporary table where all rows from each
group are consecutive, and then use this temporary table to discover
groups and apply aggregate functions (if any). In some cases, MySQL is
able to do much better than that and to avoid creation of temporary
tables by using index access.

The most important preconditions for using indexes for `GROUP BY' are
that all `GROUP BY' columns reference attributes from the same index,
and that the index stores its keys in order (for example, this is a
`BTREE' index and not a `HASH' index). Whether use of temporary tables
can be replaced by index access also depends on which parts of an index
are used in a query, the conditions specified for these parts, and the
selected aggregate functions.

In MySQL, `GROUP BY' is used for sorting, so the server may also apply
`ORDER BY' optimizations to grouping. See *Note order-by-optimization::.

There are two ways to execute a `GROUP BY' query via index access, as
detailed in the following sections.  In the first method, the grouping
operation is applied together with all range predicates (if any). The
second method first performs a range scan, and then groups the
resulting tuples.


File: manual.info,  Node: loose-index-scan,  Next: tight-index-scan,  Prev: group-by-optimization,  Up: group-by-optimization

7.2.13.1 Loose index scan
.........................

The most efficient way to process `GROUP BY' is when the index is used
to directly retrieve the group fields. With this access method, MySQL
uses the property of some index types that the keys are ordered (for
example, `BTREE'). This property enables use of lookup groups in an
index without having to consider all keys in the index that satisfy all
`WHERE' conditions.  This access method considers only a fraction of
the keys in an index, so it is called a _loose index scan_. When there
is no `WHERE' clause, a loose index scan reads as many keys as the
number of groups, which may be a much smaller number than that of all
keys. If the `WHERE' clause contains range predicates (see the
discussion of the `range' join type in *Note using-explain::), a loose
index scan looks up the first key of each group that satisfies the
range conditions, and again reads the least possible number of keys.
This is possible under the following conditions:

   * The query is over a single table.

   * The `GROUP BY' includes the first consecutive parts of the index.
     (If, instead of `GROUP BY', the query has a `DISTINCT' clause, all
     distinct attributes refer to the beginning of the index.)

   * The only aggregate functions used (if any) are `MIN()' and
     `MAX()', and all of them refer to the same column.

   * Any other parts of the index than those from the `GROUP BY'
     referenced in the query must be constants (that is, they must be
     referenced in equalities with constants), except for the argument
     of `MIN()' or `MAX()' functions.

The `EXPLAIN' output for such queries shows `Using index for group-by'
in the `Extra' column.

The following queries fall into this category, assuming that there is
an index `idx(c1,c2,c3)' on table `t1(c1,c2,c3,c4)':

     SELECT c1, c2 FROM t1 GROUP BY c1, c2;
     SELECT DISTINCT c1, c2 FROM t1;
     SELECT c1, MIN(c2) FROM t1 GROUP BY c1;
     SELECT c1, c2 FROM t1 WHERE c1 < CONST GROUP BY c1, c2;
     SELECT MAX(c3), MIN(c3), c1, c2 FROM t1 WHERE c2 > CONST GROUP BY c1, c2;
     SELECT c2 FROM t1 WHERE c1 < CONST GROUP BY c1, c2;
     SELECT c1, c2 FROM t1 WHERE c3 = CONST GROUP BY c1, c2;

The following queries cannot be executed with this quick select method,
for the reasons given:

   * There are aggregate functions other than `MIN()' or `MAX()', for
     example:

          SELECT c1, SUM(c2) FROM t1 GROUP BY c1;

   * The fields in the `GROUP BY' clause do not refer to the beginning
     of the index, as shown here:

          SELECT c1,c2 FROM t1 GROUP BY c2, c3;

   * The query refers to a part of a key that comes after the `GROUP
     BY' part, and for which there is no equality with a constant, an
     example being:

          SELECT c1,c3 FROM t1 GROUP BY c1, c2;


File: manual.info,  Node: tight-index-scan,  Prev: loose-index-scan,  Up: group-by-optimization

7.2.13.2 Tight index scan
.........................

A tight index scan may be either a full index scan or a range index
scan, depending on the query conditions.

When the conditions for a loose index scan are not met, it is still
possible to avoid creation of temporary tables for `GROUP BY' queries.
If there are range conditions in the `WHERE' clause, this method reads
only the keys that satisfy these conditions. Otherwise, it performs an
index scan. Because this method reads all keys in each range defined by
the `WHERE' clause, or scans the whole index if there are no range
conditions, we term it a _tight index scan_. Notice that with a tight
index scan, the grouping operation is performed only after all keys
that satisfy the range conditions have been found.

For this method to work, it is sufficient that there is a constant
equality condition for all columns in a query referring to parts of the
key coming before or in between parts of the `GROUP BY' key. The
constants from the equality conditions fill in any `gaps' in the search
keys so that it is possible to form complete prefixes of the index.
These index prefixes then can be used for index lookups. If we require
sorting of the `GROUP BY' result, and it is possible to form search keys
that are prefixes of the index, MySQL also avoids extra sorting
operations because searching with prefixes in an ordered index already
retrieves all the keys in order.

The following queries do not work with the loose index scan access
method described earlier, but still work with the tight index scan
access method (assuming that there is an index `idx(c1,c2,c3)' on table
`t1(c1,c2,c3,c4)').

   * There is a gap in the `GROUP BY', but it is covered by the
     condition `c2 = 'a'':

          SELECT c1, c2, c3 FROM t1 WHERE c2 = 'a' GROUP BY c1, c3;

   * The `GROUP BY' does not begin with the first part of the key, but
     there is a condition that provides a constant for that part:

          SELECT c1, c2, c3 FROM t1 WHERE c1 = 'a' GROUP BY c2, c3;


File: manual.info,  Node: distinct-optimization,  Next: in-subquery-optimization,  Prev: group-by-optimization,  Up: query-speed

7.2.14 `DISTINCT' Optimization
------------------------------

`DISTINCT' combined with `ORDER BY' needs a temporary table in many
cases.

Because `DISTINCT' may use `GROUP BY', you should be aware of how MySQL
works with columns in `ORDER BY' or `HAVING' clauses that are not part
of the selected columns. See *Note group-by-hidden-fields::.

In most cases, a `DISTINCT' clause can be considered as a special case
of `GROUP BY'. For example, the following two queries are equivalent:

     SELECT DISTINCT c1, c2, c3 FROM t1
     WHERE c1 > CONST;

     SELECT c1, c2, c3 FROM t1
     WHERE c1 > CONST GROUP BY c1, c2, c3;

Due to this equivalence, the optimizations applicable to `GROUP BY'
queries can be also applied to queries with a `DISTINCT' clause. Thus,
for more details on the optimization possibilities for `DISTINCT'
queries, see *Note group-by-optimization::.

When combining `LIMIT ROW_COUNT' with `DISTINCT', MySQL stops as soon
as it finds ROW_COUNT unique rows.

If you do not use columns from all tables named in a query, MySQL stops
scanning any unused tables as soon as it finds the first match. In the
following case, assuming that `t1' is used before `t2' (which you can
check with `EXPLAIN'), MySQL stops reading from `t2' (for any
particular row in `t1') when it finds the first row in `t2':

     SELECT DISTINCT t1.a FROM t1, t2 where t1.a=t2.a;


File: manual.info,  Node: in-subquery-optimization,  Next: limit-optimization,  Prev: distinct-optimization,  Up: query-speed

7.2.15 Optimizing `IN'/`=ANY' Subqueries
----------------------------------------

Certain optimizations are applicable to comparisons that use the `IN'
operator to test subquery results (or that use `=ANY', which is
equivalent). This section discusses these optimizations, particularly
with regard to the challenges that `NULL' values present.  Suggestions
on what you can do to help the optimizer are given at the end of the
discussion.

Consider the following subquery comparison:

     OUTER_EXPR IN (SELECT INNER_EXPR FROM ... WHERE SUBQUERY_WHERE)

MySQL evaluates queries `from outside to inside.' That is, it first
obtains the value of the outer expression OUTER_EXPR, and then runs the
subquery and captures the rows that it produces.

A very useful optimization is to `inform' the subquery that the only
rows of interest are those where the inner expression INNER_EXPR is
equal to OUTER_EXPR. This is done by pushing down an appropriate
equality into the subquery's `WHERE' clause. That is, the comparison is
converted to this:

     EXISTS (SELECT 1 FROM ... WHERE SUBQUERY_WHERE AND OUTER_EXPR=INNER_EXPR)

After the conversion, MySQL can use the pushed-down equality to limit
the number of rows that it must examine when evaluating the subquery.

More generally, a comparison of N values to a subquery that returns
N-value rows is subject to the same conversion. If OE_I and IE_I
represent corresponding outer and inner expression values, this
subquery comparison:

     (OE_1, ..., OE_N) IN
       (SELECT IE_1, ..., IE_N FROM ... WHERE SUBQUERY_WHERE)

Becomes:

     EXISTS (SELECT 1 FROM ... WHERE SUBQUERY_WHERE
                               AND OE_1 = IE_1
                               AND ...
                               AND OE_N = IE_N)

The following discussion assumes a single pair of outer and inner
expression values for simplicity.

The conversion just described has its limitations. It is valid only if
we ignore possible `NULL' values. That is, the `pushdown' strategy
works as long as both of these two conditions are true:

   * OUTER_EXPR and INNER_EXPR cannot be `NULL'.

   * You do not need to distinguish `NULL' from `FALSE' subquery
     results. (If the subquery is a part of an `OR' or `AND' expression
     in the `WHERE' clause, MySQL assumes that you don't care.)

When either or both of those conditions do not hold, optimization is
more complex.

Suppose that OUTER_EXPR is known to be a non-`NULL' value but the
subquery does not produce a row such that OUTER_EXPR = INNER_EXPR. Then
`OUTER_EXPR IN (SELECT ...)' evaluates as follows:

   * `NULL', if the `SELECT' produces any row where INNER_EXPR is `NULL'

   * `FALSE', if the `SELECT' produces only non-`NULL' values or
     produces nothing

In this situation, the approach of looking for rows with `OUTER_EXPR =
INNER_EXPR' is no longer valid. It is necessary to look for such rows,
but if none are found, also look for rows where INNER_EXPR is `NULL'.
Roughly speaking, the subquery can be converted to:

     EXISTS (SELECT 1 FROM ... WHERE SUBQUERY_WHERE AND
             (OUTER_EXPR=INNER_EXPR OR INNER_EXPR IS NULL))

The need to evaluate the extra `IS NULL' condition is why MySQL has the
`ref_or_null' access method:

     mysql> EXPLAIN
         -> SELECT OUTER_EXPR IN (SELECT t2.maybe_null_key
         ->                       FROM t2, t3 WHERE ...)
         -> FROM t1;
     *************************** 1. row ***************************
                id: 1
       select_type: PRIMARY
             table: t1
     ...
     *************************** 2. row ***************************
                id: 2
       select_type: DEPENDENT SUBQUERY
             table: t2
              type: ref_or_null
     possible_keys: maybe_null_key
               key: maybe_null_key
           key_len: 5
               ref: func
              rows: 2
             Extra: Using where; Using index
     ...

The `unique_subquery' and `index_subquery' subquery-specific access
methods also have or-null variants. However, they are not visible in
`EXPLAIN' output, so you must use `EXPLAIN EXTENDED' followed by `SHOW
WARNINGS' (note the `checking NULL' in the warning message):

     mysql> EXPLAIN EXTENDED
         -> SELECT OUTER_EXPR IN (SELECT maybe_null_key FROM t2) FROM t1\G
     *************************** 1. row ***************************
                id: 1
       select_type: PRIMARY
             table: t1
     ...
     *************************** 2. row ***************************
                id: 2
       select_type: DEPENDENT SUBQUERY
             table: t2
              type: index_subquery
     possible_keys: maybe_null_key
               key: maybe_null_key
           key_len: 5
               ref: func
              rows: 2
             Extra: Using index

     mysql> SHOW WARNINGS\G
     *************************** 1. row ***************************
       Level: Note
        Code: 1003
     Message: select (`test`.`t1`.`outer_expr`,
              (((`test`.`t1`.`outer_expr`) in t2 on
              maybe_null_key checking NULL))) AS `outer_expr IN (SELECT
              maybe_null_key FROM t2)` from `test`.`t1`

The additional `OR ... IS NULL' condition makes query execution
slightly more complicated (and some optimizations within the subquery
become inapplicable), but generally this is tolerable.

The situation is much worse when OUTER_EXPR can be `NULL'. According to
the SQL interpretation of `NULL' as `unknown value,' `NULL IN (SELECT
INNER_EXPR ...)' should evaluate to:

   * `NULL', if the `SELECT' produces any rows

   * `FALSE', if the `SELECT' produces no rows

For proper evaluation, it is necessary to be able to check whether the
`SELECT' has produced any rows at all, so `OUTER_EXPR = INNER_EXPR'
cannot be pushed down into the subquery. This is a problem, because
many real world subqueries become very slow unless the equality can be
pushed down.

Essentially, there must be different ways to execute the subquery
depending on the value of OUTER_EXPR. In MySQL 5.1 before 5.1.16, the
optimizer chose speed over distinguishing a `NULL' from `FALSE' result,
so for some queries, you might get a `FALSE' result rather than `NULL'.

As of MySQL 5.1.16, the optimizer chooses SQL compliance over speed, so
it accounts for the possibility that OUTER_EXPR might be `NULL'.

If OUTER_EXPR is `NULL', to evaluate the following expression, it is
necessary to run the `SELECT' to determine whether it produces any rows:

     NULL IN (SELECT INNER_EXPR FROM ... WHERE SUBQUERY_WHERE)

It is necessary to run the original `SELECT' here, without any
pushed-down equalities of the kind mentioned earlier.

On the other hand, when OUTER_EXPR is not `NULL', it is absolutely
essential that this comparison:

     OUTER_EXPR IN (SELECT INNER_EXPR FROM ... WHERE SUBQUERY_WHERE)

be converted to this expression that uses a pushed-down condition:

     EXISTS (SELECT 1 FROM ... WHERE SUBQUERY_WHERE AND OUTER_EXPR=INNER_EXPR)

Without this conversion, subqueries will be slow. To solve the dilemma
of whether to push down or not push down conditions into the subquery,
the conditions are wrapped in `trigger' functions. Thus, an expression
of the following form:

     OUTER_EXPR IN (SELECT INNER_EXPR FROM ... WHERE SUBQUERY_WHERE)

is converted into:

     EXISTS (SELECT 1 FROM ... WHERE SUBQUERY_WHERE
                               AND trigcond(OUTER_EXPR=INNER_EXPR))

More generally, if the subquery comparison is based on several pairs of
outer and inner expressions, the conversion takes this comparison:

     (OE_1, ..., OE_N) IN (SELECT IE_1, ..., IE_N FROM ... WHERE SUBQUERY_WHERE)

and converts it to this expression:

     EXISTS (SELECT 1 FROM ... WHERE SUBQUERY_WHERE
                               AND trigcond(OE_1=IE_1)
                               AND ...
                               AND trigcond(OE_N=IE_N)
            )

Each `trigcond(X)' is a special function that evaluates to the
following values:

   * X when the `linked' outer expression OE_I is not `NULL'

   * `TRUE' when the `linked' outer expression OE_I is `NULL'

Note that trigger functions are _not_ triggers of the kind that you
create with `CREATE TRIGGER'.

Equalities that are wrapped into `trigcond()' functions are not first
class predicates for the query optimizer. Most optimizations cannot
deal with predicates that may be turned on and off at query execution
time, so they assume any `trigcond(X)' to be an unknown function and
ignore it. At the moment, triggered equalities can be used by those
optimizations:

   * Reference optimizations: `trigcond(X=Y [OR Y IS NULL])' can be
     used to construct `ref', `eq_ref', or `ref_or_null' table accesses.

   * Index lookup-based subquery execution engines: `trigcond(X=Y)' can
     be used to construct `unique_subquery' or `index_subquery'
     accesses.

   * Table-condition generator: If the subquery is a join of several
     tables, the triggered condition will be checked as soon as
     possible.

When the optimizer uses a triggered condition to create some kind of
index lookup-based access (as for the first two items of the preceding
list), it must have a fallback strategy for the case when the condition
is turned off. This fallback strategy is always the same: Do a full
table scan. In `EXPLAIN' output, the fallback shows up as `Full scan on
NULL key' in the `Extra' column:

     mysql> EXPLAIN SELECT t1.col1,
         -> t1.col1 IN (SELECT t2.key1 FROM t2 WHERE t2.col2=t1.col2) FROM t1\G
     *************************** 1. row ***************************
                id: 1
       select_type: PRIMARY
             table: t1
             ...
     *************************** 2. row ***************************
                id: 2
       select_type: DEPENDENT SUBQUERY
             table: t2
              type: index_subquery
     possible_keys: key1
               key: key1
           key_len: 5
               ref: func
              rows: 2
             Extra: Using where; Full scan on NULL key

If you run `EXPLAIN EXTENDED' followed by `SHOW WARNINGS', you can see
the triggered condition:

     *************************** 1. row ***************************
       Level: Note
        Code: 1003
     Message: select `test`.`t1`.`col1` AS `col1`,
              <in_optimizer>(`test`.`t1`.`col1`,
              <exists>(<index_lookup>(<cache>(`test`.`t1`.`col1`) in t2
              on key1 checking NULL
              where (`test`.`t2`.`col2` = `test`.`t1`.`col2`) having
              trigcond(<is_not_null_test>(`test`.`t2`.`key1`))))) AS
              `t1.col1 IN (select t2.key1 from t2 where t2.col2=t1.col2)`
              from `test`.`t1`

The use of triggered conditions has some performance implications. A
`NULL IN (SELECT ...)' expression now may cause a full table scan
(which is slow) when it previously did not. This is the price paid for
correct results (the goal of the trigger-condition strategy was to
improve compliance and not speed).

For multiple-table subqueries, execution of `NULL IN (SELECT ...)' will
be particularly slow because the join optimizer doesn't optimize for
the case where the outer expression is `NULL'. It assumes that subquery
evaluations with `NULL' on the left side are very rare, even if there
are statistics that indicate otherwise.  On the other hand, if the
outer expression might be `NULL' but never actually is, there is no
performance penalty.

To help the query optimizer better execute your queries, use these tips:

   * A column must be declared as `NOT NULL' if it really is. (This
     also helps other aspects of the optimizer.)

   * If you don't need to distinguish a `NULL' from `FALSE' subquery
     result, you can easily avoid the slow execution path. Replace a
     comparison that looks like this:

          OUTER_EXPR IN (SELECT INNER_EXPR FROM ...)

     with this expression:

          (OUTER_EXPR IS NOT NULL) AND (OUTER_EXPR IN (SELECT INNER_EXPR FROM ...))

     Then `NULL IN (SELECT ...)' will never be evaluated because MySQL
     stops evaluating `AND' parts as soon as the expression result is
     clear.


File: manual.info,  Node: limit-optimization,  Next: how-to-avoid-table-scan,  Prev: in-subquery-optimization,  Up: query-speed

7.2.16 `LIMIT' Optimization
---------------------------

In some cases, MySQL handles a query differently when you are using
`LIMIT ROW_COUNT' and not using `HAVING':

   * If you are selecting only a few rows with `LIMIT', MySQL uses
     indexes in some cases when normally it would prefer to do a full
     table scan.

   * If you use `LIMIT ROW_COUNT' with `ORDER BY', MySQL ends the
     sorting as soon as it has found the first ROW_COUNT rows of the
     sorted result, rather than sorting the entire result. If ordering
     is done by using an index, this is very fast. If a filesort must
     be done, all rows that match the query without the `LIMIT' clause
     must be selected, and most or all of them must be sorted, before
     it can be ascertained that the first ROW_COUNT rows have been
     found. In either case, after the initial rows have been found,
     there is no need to sort any remainder of the result set, and
     MySQL does not do so.

   * When combining `LIMIT ROW_COUNT' with `DISTINCT', MySQL stops as
     soon as it finds ROW_COUNT unique rows.

   * In some cases, a `GROUP BY' can be resolved by reading the key in
     order (or doing a sort on the key) and then calculating summaries
     until the key value changes. In this case, `LIMIT ROW_COUNT' does
     not calculate any unnecessary `GROUP BY' values.

   * As soon as MySQL has sent the required number of rows to the
     client, it aborts the query unless you are using
     `SQL_CALC_FOUND_ROWS'.

   * `LIMIT 0' quickly returns an empty set.  This can be useful for
     checking the validity of a query.  When using one of the MySQL
     APIs, it can also be employed for obtaining the types of the
     result columns. (This trick does not work in the MySQL Monitor (the
     `mysql' program), which merely displays `Empty set' in such cases;
     you should instead use `SHOW COLUMNS' or `DESCRIBE' for this
     purpose.)

   * When the server uses temporary tables to resolve the query, it
     uses the `LIMIT ROW_COUNT' clause to calculate how much space is
     required.


File: manual.info,  Node: how-to-avoid-table-scan,  Next: information-schema-optimization,  Prev: limit-optimization,  Up: query-speed

7.2.17 How to Avoid Table Scans
-------------------------------

The output from `EXPLAIN' shows `ALL' in the `type' column when MySQL
uses a table scan to resolve a query. This usually happens under the
following conditions:

   * The table is so small that it is faster to perform a table scan
     than to bother with a key lookup. This is common for tables with
     fewer than 10 rows and a short row length.

   * There are no usable restrictions in the `ON' or `WHERE' clause for
     indexed columns.

   * You are comparing indexed columns with constant values and MySQL
     has calculated (based on the index tree) that the constants cover
     too large a part of the table and that a table scan would be
     faster. See *Note where-optimizations::.

   * You are using a key with low cardinality (many rows match the key
     value) through another column. In this case, MySQL assumes that by
     using the key it probably will do many key lookups and that a
     table scan would be faster.

MySQL Enterprise

For expert advice on avoiding excessive table scans subscribe to the
MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

For small tables, a table scan often is appropriate and the performance
impact is negligible. For large tables, try the following techniques to
avoid having the optimizer incorrectly choose a table scan:

   * Use `ANALYZE TABLE TBL_NAME' to update the key distributions for
     the scanned table. See *Note analyze-table::.

   * Use `FORCE INDEX' for the scanned table to tell MySQL that table
     scans are very expensive compared to using the given index:

          SELECT * FROM t1, t2 FORCE INDEX (INDEX_FOR_COLUMN)
            WHERE t1.COL_NAME=t2.COL_NAME;

     See *Note index-hints::.

   * Start `mysqld' with the `--max-seeks-for-key=1000' option or use
     `SET max_seeks_for_key=1000' to tell the optimizer to assume that
     no key scan causes more than 1,000 key seeks. See *Note
     server-system-variables::.


File: manual.info,  Node: information-schema-optimization,  Next: insert-speed,  Prev: how-to-avoid-table-scan,  Up: query-speed

7.2.18 `INFORMATION_SCHEMA' Optimization
----------------------------------------

In MySQL 5.1.23, changes to the implementation of `INFORMATION_SCHEMA'
were made that optimize certain types of queries for
`INFORMATION_SCHEMA' tables so that they execute more quickly. This
section provides guidelines on writing queries that take advantage of
these optimizations. In general, the strategies outlined here minimize
the need for the server to access the filesystem to obtain the
information that makes up the contents of `INFORMATION_SCHEMA' tables.
By writing queries that enable the server to avoid directory scans or
opening table files, you will obtain better performance.

*1) Try to use constant lookup values for database and table names in
the `WHERE' clause*

You can take advantage of this principle as follows:

   * To look up databases or tables, use expressions that evaluate to a
     constant, such as literal values, functions that return a
     constant, or scalar subqueries.

   * Avoid queries that use a non-constant database name lookup value
     (or no lookup value) because they require a scan of the data
     directory to find matching database directory names.

   * Within a database, avoid queries that use a non-constant table
     name lookup value (or no lookup value) because they require a scan
     of the database directory to find matching table files.

This principle applies to the `INFORMATION_SCHEMA' tables shown in the
following table, which shows the columns for which a constant lookup
value enables the server to avoid a directory scan. For example, if you
are selecting from `TABLES', using a constant lookup value for
`TABLE_SCHEMA' in the `WHERE' clause enables a data directory scan to
be avoided.

*Table*                  *Column to specify to    *Column to specify to
                         avoid data directory     avoid database directory
                         scan*                    scan*
`COLUMNS'                `TABLE_SCHEMA'           `TABLE_NAME'
`KEY_COLUMN_USAGE'       `TABLE_SCHEMA'           `TABLE_NAME'
`PARTITIONS'             `TABLE_SCHEMA'           `TABLE_NAME'
`REFERENTIAL_CONSTRAINTS'`CONSTRAINT_SCHEMA'      `TABLE_NAME'
`STATISTICS'             `TABLE_SCHEMA'           `TABLE_NAME'
`TABLES'                 `TABLE_SCHEMA'           `TABLE_NAME'
`TABLE_CONSTRAINTS'      `TABLE_SCHEMA'           `TABLE_NAME'
`TRIGGERS'               `EVENT_OBJECT_SCHEMA'    `EVENT_OBJECT_TABLE'
`VIEWS'                  `TABLE_SCHEMA'           `TABLE_NAME'

The benefit of a query that is limited to a specific constant database
name is that checks need be made only for the named database directory.
Example:

     SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES
     WHERE TABLE_SCHEMA = 'test';

Use of the literal database name `test' enables the server to check
only the `test' database directory, regardless of how many databases
there might be. By contrast, the following query is less efficient
because it requires a scan of the data directory to determine which
database names match the pattern `'test%'':

     SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES
     WHERE TABLE_SCHEMA LIKE 'test%';

For a query that is limited to a specific constant table name, checks
need be made only for the named table within the corresponding database
directory. Example:

     SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES
     WHERE TABLE_SCHEMA = 'test' AND TABLE_NAME = 't1';

Use of the literal table name `t1' enables the server to check only the
files for the `t1' table, regardless of how many tables there might be
in the `test' database. By contrast, the following query requires a
scan of the `test' database directory to determine which table names
match the pattern `'t%'':

     SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES
     WHERE TABLE_SCHEMA = 'test' AND TABLE_NAME LIKE 't%';

The following query requires a scan of the database directory to
determine matching database names for the pattern `'test%'', and for
each matching database, it requires a scan of the database directory to
determine matching table names for the pattern `'t%'':

     SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES
     WHERE TABLE_SCHEMA = 'test%' AND TABLE_NAME LIKE 't%';

*2) Write queries that minimize the number of table files that must be
opened*

For queries that refer to certain `INFORMATION_SCHEMA' table columns,
several optimizations are available that minimize the number of table
files that must be opened. Example:

     SELECT TABLE_NAME, ENGINE FROM INFORMATION_SCHEMA.TABLES
     WHERE TABLE_SCHEMA = 'test';

In this case, after the server has scanned the database directory to
determine the names of the tables in the database, those names become
available with no further filesystem lookups.  Thus, `TABLE_NAME'
requires no files to be opened. The `ENGINE' (storage engine) value can
be determined by opening the table's `.frm' file, without touching
other table files such as the `.MYD' or `.MYI' file.

Some values, such as `INDEX_LENGTH' for `MyISAM' tables, require
opening the `.MYD' or `.MYI' file as well.

The file-opening optimization types are denoted thus:

   * `SKIP_OPEN_TABLE': Table files do not need to be opened. The
     information has already become available within the query by
     scanning the database directory.

   * `OPEN_FRM_ONLY': Only the table's `.frm' file need be opened.

   * `OPEN_TRIGGER_ONLY': Only the table's `.TRG' file need be opened.

   * `OPEN_FULL_TABLE': The unoptimized information lookup. The `.frm',
     `.MYD', and `.MYI' files must be opened.

The following list indicates how the preceding optimization types apply
to `INFORMATION_SCHEMA' table columns. For tables and columns not
named, none of the optimizations apply.

   * `COLUMNS': `OPEN_FRM_ONLY' applies to all columns

   * `KEY_COLUMN_USAGE': `OPEN_FULL_TABLE' applies to all columns

   * `PARTITIONS': `OPEN_FULL_TABLE' applies to all columns

   * `REFERENTIAL_CONSTRAINTS': `OPEN_FULL_TABLE' applies to all columns

   * `STATISTICS':

     *Column*                           *Optimization type*
     `TABLE_CATALOG'                    `OPEN_FRM_ONLY'
     `TABLE_SCHEMA'                     `OPEN_FRM_ONLY'
     `TABLE_NAME'                       `OPEN_FRM_ONLY'
     `NON_UNIQUE'                       `OPEN_FRM_ONLY'
     `INDEX_SCHEMA'                     `OPEN_FRM_ONLY'
     `INDEX_NAME'                       `OPEN_FRM_ONLY'
     `SEQ_IN_INDEX'                     `OPEN_FRM_ONLY'
     `COLUMN_NAME'                      `OPEN_FRM_ONLY'
     `COLLATION'                        `OPEN_FRM_ONLY'
     `CARDINALITY'                      `OPEN_FULL_TABLE'
     `SUB_PART'                         `OPEN_FRM_ONLY'
     `PACKED'                           `OPEN_FRM_ONLY'
     `NULLABLE'                         `OPEN_FRM_ONLY'
     `INDEX_TYPE'                       `OPEN_FULL_TABLE'
     `COMMENT'                          `OPEN_FRM_ONLY'

   * `TABLES':

     *Column*                           *Optimization type*
     `TABLE_CATALOG'                    `SKIP_OPEN_TABLE'
     `TABLE_SCHEMA'                     `SKIP_OPEN_TABLE'
     `TABLE_NAME'                       `SKIP_OPEN_TABLE'
     `TABLE_TYPE'                       `OPEN_FRM_ONLY'
     `ENGINE'                           `OPEN_FRM_ONLY'
     `VERSION'                          `OPEN_FRM_ONLY'
     `ROW_FORMAT'                       `OPEN_FULL_TABLE'
     `TABLE_ROWS'                       `OPEN_FULL_TABLE'
     `AVG_ROW_LENGTH'                   `OPEN_FULL_TABLE'
     `DATA_LENGTH'                      `OPEN_FULL_TABLE'
     `MAX_DATA_LENGTH'                  `OPEN_FULL_TABLE'
     `INDEX_LENGTH'                     `OPEN_FULL_TABLE'
     `DATA_FREE'                        `OPEN_FULL_TABLE'
     `AUTO_INCREMENT'                   `OPEN_FULL_TABLE'
     `CREATE_TIME'                      `OPEN_FULL_TABLE'
     `UPDATE_TIME'                      `OPEN_FULL_TABLE'
     `CHECK_TIME'                       `OPEN_FULL_TABLE'
     `TABLE_COLLATION'                  `OPEN_FRM_ONLY'
     `CHECKSUM'                         `OPEN_FULL_TABLE'
     `CREATE_OPTIONS'                   `OPEN_FRM_ONLY'
     `TABLE_COMMENT'                    `OPEN_FRM_ONLY'

   * `TABLE_CONSTRAINTS': `OPEN_FULL_TABLE' applies to all columns

   * `TRIGGERS': `OPEN_FULL_TABLE' applies to all columns

   * `VIEWS':

     *Column*                           *Optimization type*
     `TABLE_CATALOG'                    `OPEN_FRM_ONLY'
     `TABLE_SCHEMA'                     `OPEN_FRM_ONLY'
     `TABLE_NAME'                       `OPEN_FRM_ONLY'
     `VIEW_DEFINITION'                  `OPEN_FULL_TABLE'
     `CHECK_OPTION'                     `OPEN_FULL_TABLE'
     `IS_UPDATABLE'                     `OPEN_FULL_TABLE'
     `DEFINER'                          `OPEN_FULL_TABLE'
     `SECURITY_TYPE'                    `OPEN_FULL_TABLE'
     `CHARACTER_SET_CLIENT'             `OPEN_FULL_TABLE'
     `COLLATION_CONNECTION'             `OPEN_FULL_TABLE'

*3) Use `EXPLAIN' to determine whether the server can use
`INFORMATION_SCHEMA' optimizations for a query*

The `Extra' value in `EXPLAIN' output indicates which, if any, of the
optimizations described earlier the server can use to evaluate
`INFORMATION_SCHEMA' queries. The following examples demonstrate the
kinds of information you can expect to see in the `Extra' value.

     mysql> EXPLAIN SELECT TABLE_NAME FROM INFORMATION_SCHEMA.VIEWS WHERE
         -> TABLE_SCHEMA = 'test' AND TABLE_NAME = 'v1'\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: VIEWS
              type: ALL
     possible_keys: NULL
               key: TABLE_SCHEMA,TABLE_NAME
           key_len: NULL
               ref: NULL
              rows: NULL
             Extra: Using where; Open_frm_only; Scanned 0 databases

Use of constant database and table lookup values enables the server to
avoid directory scans. For references to `VIEWS.TABLE_NAME', only the
`.frm' file need be opened.

     mysql> EXPLAIN SELECT TABLE_NAME, ROW_FORMAT FROM INFORMATION_SCHEMA.TABLES\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: TABLES
              type: ALL
     possible_keys: NULL
               key: NULL
           key_len: NULL
               ref: NULL
              rows: NULL
             Extra: Open_full_table; Scanned all databases

No lookup values are provided (there is no `WHERE' clause), so the
server must scan the data directory and each database directory. For
each table thus identified, the table name and row format are selected.
`TABLE_NAME' requires no further table files to be opened (the
`SKIP_OPEN_TABLE' optimization applies). `ROW_FORMAT' requires all
table files to be opened (`OPEN_FULL_TABLE' applies).  `EXPLAIN' reports
`OPEN_FULL_TABLE' because it is more expensive than `SKIP_OPEN_TABLE'.

     mysql> EXPLAIN SELECT TABLE_NAME, TABLE_TYPE FROM INFORMATION_SCHEMA.TABLES
         -> WHERE TABLE_SCHEMA = 'test'\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: TABLES
              type: ALL
     possible_keys: NULL
               key: TABLE_SCHEMA
           key_len: NULL
               ref: NULL
              rows: NULL
             Extra: Using where; Open_frm_only; Scanned 1 database

No table name lookup value is provided, so the server must scan the
`test' database directory. For the `TABLE_NAME' and `TABLE_TYPE'
columns, the `SKIP_OPEN_TABLE' and `OPEN_FRM_ONLY' optimizations apply,
respectively. `EXPLAIN' reports `OPEN_FRM_ONLY' because it is more
expensive.

     mysql> EXPLAIN SELECT B.TABLE_NAME
         -> FROM INFORMATION_SCHEMA.TABLES AS A, INFORMATION_SCHEMA.COLUMNS AS B
         -> WHERE A.TABLE_SCHEMA = 'test'
         -> AND A.TABLE_NAME = 't1'
         -> AND B.TABLE_NAME = A.TABLE_NAME\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: A
              type: ALL
     possible_keys: NULL
               key: TABLE_SCHEMA,TABLE_NAME
           key_len: NULL
               ref: NULL
              rows: NULL
             Extra: Using where; Skip_open_table; Scanned 0 databases
     *************************** 2. row ***************************
                id: 1
       select_type: SIMPLE
             table: B
              type: ALL
     possible_keys: NULL
               key: NULL
           key_len: NULL
               ref: NULL
              rows: NULL
             Extra: Using where; Open_frm_only; Scanned all databases;
                    Using join buffer

For the first `EXPLAIN' output row: Constant database and table lookup
values enable the server to avoid directory scans for `TABLES' values.
References to `TABLES.TABLE_NAME' require no further table files.

For the second `EXPLAIN' output row: All `COLUMNS' table values are
`OPEN_FRM_ONLY' lookups, so `COLUMNS.TABLE_NAME' requires the `.frm'
file to be opened.

     mysql> EXPLAIN SELECT * FROM INFORMATION_SCHEMA.COLLATIONS\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: COLLATIONS
              type: ALL
     possible_keys: NULL
               key: NULL
           key_len: NULL
               ref: NULL
              rows: NULL
             Extra:

In this case, no optimizations apply because `COLLATIONS' is not one of
the `INFORMATION_SCHEMA' tables for which optimizations are available.


File: manual.info,  Node: insert-speed,  Next: update-speed,  Prev: information-schema-optimization,  Up: query-speed

7.2.19 Speed of `INSERT' Statements
-----------------------------------

The time required for inserting a row is determined by the following
factors, where the numbers indicate approximate proportions:

   * Connecting: (3)

   * Sending query to server: (2)

   * Parsing query: (2)

   * Inserting row: (1 x size of row)

   * Inserting indexes: (1 x number of indexes)

   * Closing: (1)

This does not take into consideration the initial overhead to open
tables, which is done once for each concurrently running query.

The size of the table slows down the insertion of indexes by log N,
assuming B-tree indexes.

You can use the following methods to speed up inserts:

   * If you are inserting many rows from the same client at the same
     time, use `INSERT' statements with multiple `VALUES' lists to
     insert several rows at a time. This is considerably faster (many
     times faster in some cases) than using separate single-row
     `INSERT' statements. If you are adding data to a non-empty table,
     you can tune the `bulk_insert_buffer_size' variable to make data
     insertion even faster. See *Note server-system-variables::.

   * If multiple clients are inserting a lot of rows, you can get
     higher speed by using the `INSERT DELAYED' statement. See *Note
     insert-delayed::.

   * For a `MyISAM' table, you can use concurrent inserts to add rows
     at the same time that `SELECT' statements are running, if there
     are no deleted rows in middle of the data file. See *Note
     concurrent-inserts::.

   * When loading a table from a text file, use `LOAD DATA INFILE'.
     This is usually 20 times faster than using `INSERT' statements. See
     *Note load-data::.

   * With some extra work, it is possible to make `LOAD DATA INFILE'
     run even faster for a `MyISAM' table when the table has many
     indexes. Use the following procedure:

       1. Optionally create the table with `CREATE TABLE'.

       2. Execute a `FLUSH TABLES' statement or a `mysqladmin
          flush-tables' command.

       3. Use `myisamchk --keys-used=0 -rq /PATH/TO/DB/TBL_NAME.' This
          removes all use of indexes for the table.

       4. Insert data into the table with `LOAD DATA INFILE'. This does
          not update any indexes and therefore is very fast.

       5. If you intend only to read from the table in the future, use
          `myisampack' to compress it. See *Note compressed-format::.

       6. Re-create the indexes with `myisamchk -rq
          /PATH/TO/DB/TBL_NAME'.  This creates the index tree in memory
          before writing it to disk, which is much faster that updating
          the index during `LOAD DATA INFILE' because it avoids lots of
          disk seeks. The resulting index tree is also perfectly
          balanced.

       7. Execute a `FLUSH TABLES' statement or a `mysqladmin
          flush-tables' command.

     `LOAD DATA INFILE' performs the preceding optimization
     automatically if the `MyISAM' table into which you insert data is
     empty. The main difference between automatic optimization and
     using the procedure explicitly is that you can let `myisamchk'
     allocate much more temporary memory for the index creation than
     you might want the server to allocate for index re-creation when
     it executes the `LOAD DATA INFILE' statement.

     You can also disable or enable the non-unique indexes for a
     `MyISAM' table by using the following statements rather than
     `myisamchk'. If you use these statements, you can skip the `FLUSH
     TABLE' operations:

          ALTER TABLE TBL_NAME DISABLE KEYS;
          ALTER TABLE TBL_NAME ENABLE KEYS;

   * To speed up `INSERT' operations that are performed with multiple
     statements for non-transactional tables, lock your tables:

          LOCK TABLES a WRITE;
          INSERT INTO a VALUES (1,23),(2,34),(4,33);
          INSERT INTO a VALUES (8,26),(6,29);
          ...
          UNLOCK TABLES;

     This benefits performance because the index buffer is flushed to
     disk only once, after all `INSERT' statements have completed.
     Normally, there would be as many index buffer flushes as there are
     `INSERT' statements. Explicit locking statements are not needed if
     you can insert all rows with a single `INSERT'.

     To obtain faster insertions for transactional tables, you should
     use `START TRANSACTION' and `COMMIT' instead of `LOCK TABLES'.

     Locking also lowers the total time for multiple-connection tests,
     although the maximum wait time for individual connections might go
     up because they wait for locks. Suppose that five clients attempt
     to perform inserts simultaneously as follows:

        * Connection 1 does 1000 inserts

        * Connections 2, 3, and 4 do 1 insert

        * Connection 5 does 1000 inserts

     If you do not use locking, connections 2, 3, and 4 finish before 1
     and 5. If you use locking, connections 2, 3, and 4 probably do not
     finish before 1 or 5, but the total time should be about 40%
     faster.

     `INSERT', `UPDATE', and `DELETE' operations are very fast in MySQL,
     but you can obtain better overall performance by adding locks
     around everything that does more than about five successive
     inserts or updates. If you do very many successive inserts, you
     could do a `LOCK TABLES' followed by an `UNLOCK TABLES' once in a
     while (each 1,000 rows or so) to allow other threads access to the
     table. This would still result in a nice performance gain.

     `INSERT' is still much slower for loading data than `LOAD DATA
     INFILE', even when using the strategies just outlined.

   * To increase performance for `MyISAM' tables, for both `LOAD DATA
     INFILE' and `INSERT', enlarge the key cache by increasing the
     `key_buffer_size' system variable. See *Note server-parameters::.

MySQL Enterprise

For more advice on optimizing the performance of your server, subscribe
to the MySQL Enterprise Monitor. Numerous advisors are dedicated to
monitoring performance. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: update-speed,  Next: delete-speed,  Prev: insert-speed,  Up: query-speed

7.2.20 Speed of `UPDATE' Statements
-----------------------------------

An update statement is optimized like a `SELECT' query with the
additional overhead of a write. The speed of the write depends on the
amount of data being updated and the number of indexes that are updated.
Indexes that are not changed do not get updated.

Another way to get fast updates is to delay updates and then do many
updates in a row later. Performing multiple updates together is much
quicker than doing one at a time if you lock the table.

For a `MyISAM' table that uses dynamic row format, updating a row to a
longer total length may split the row. If you do this often, it is very
important to use `OPTIMIZE TABLE' occasionally. See *Note
optimize-table::.


File: manual.info,  Node: delete-speed,  Next: miscellaneous-optimization-tips,  Prev: update-speed,  Up: query-speed

7.2.21 Speed of `DELETE' Statements
-----------------------------------

The time required to delete individual rows is exactly proportional to
the number of indexes. To delete rows more quickly, you can increase
the size of the key cache by increasing the `key_buffer_size' system
variable. See *Note server-parameters::.

To delete all rows from a table, `TRUNCATE TABLE TBL_NAME' is faster
than than `DELETE FROM Truncate operations are not transaction-safe; an
error occurs when attempting one in the course of an active transaction
or active table lock.  TBL_NAME'. See *Note truncate::.


File: manual.info,  Node: miscellaneous-optimization-tips,  Prev: delete-speed,  Up: query-speed

7.2.22 Other Optimization Tips
------------------------------

This section lists a number of miscellaneous tips for improving query
processing speed:

   * Use persistent connections to the database to avoid connection
     overhead. If you cannot use persistent connections and you are
     initiating many new connections to the database, you may want to
     change the value of the `thread_cache_size' variable. See *Note
     server-parameters::.

   * Always check whether all your queries really use the indexes that
     you have created in the tables. In MySQL, you can do this with the
     `EXPLAIN' statement. See *Note using-explain::.

   * Try to avoid complex `SELECT' queries on `MyISAM' tables that are
     updated frequently, to avoid problems with table locking that occur
     due to contention between readers and writers.

   * `MyISAM' supports concurrent inserts: If a table has no free
     blocks in the middle of the data file, you can `INSERT' new rows
     into it at the same time that other threads are reading from the
     table. If it is important to be able to do this, you should
     consider using the table in ways that avoid deleting rows. Another
     possibility is to run `OPTIMIZE TABLE' to defragment the table
     after you have deleted a lot of rows from it. This behavior is
     altered by setting the `concurrent_insert' variable. You can force
     new rows to be appended (and therefore allow concurrent inserts),
     even in tables that have deleted rows. See *Note
     concurrent-inserts::.

     MySQL Enterprise

     For optimization tips geared to your specific circumstances
     subscribe to the MySQL Enterprise Monitor.  For more information,
     see `http://www.mysql.com/products/enterprise/advisors.html'.

   * To fix any compression issues that may have occurred with
     `ARCHIVE' tables, you can use `OPTIMIZE TABLE'. See *Note
     archive-storage-engine::.

   * Use `ALTER TABLE ... ORDER BY EXPR1, EXPR2, ...' if you usually
     retrieve rows in `EXPR1, EXPR2, ...' order. By using this option
     after extensive changes to the table, you may be able to get
     higher performance.

   * In some cases, it may make sense to introduce a column that is
     `hashed' based on information from other columns. If this column
     is short, reasonably unique, and indexed, it may be much faster
     than a `wide' index on many columns. In MySQL, it is very easy to
     use this extra column:

          SELECT * FROM TBL_NAME
            WHERE HASH_COL=MD5(CONCAT(COL1,COL2))
            AND COL1='CONSTANT' AND COL2='CONSTANT';

   * For `MyISAM' tables that change frequently, you should try to
     avoid all variable-length columns (`VARCHAR', `BLOB', and `TEXT').
     The table uses dynamic row format if it includes even a single
     variable-length column. See *Note storage-engines::.

   * It is normally not useful to split a table into different tables
     just because the rows become large. In accessing a row, the
     biggest performance hit is the disk seek needed to find the first
     byte of the row. After finding the data, most modern disks can
     read the entire row fast enough for most applications. The only
     cases where splitting up a table makes an appreciable difference
     is if it is a `MyISAM' table using dynamic row format that you can
     change to a fixed row size, or if you very often need to scan the
     table but do not need most of the columns. See *Note
     storage-engines::.

   * If you often need to calculate results such as counts based on
     information from a lot of rows, it may be preferable to introduce
     a new table and update the counter in real time.  An update of the
     following form is very fast:

          UPDATE TBL_NAME SET COUNT_COL=COUNT_COL+1 WHERE KEY_COL=CONSTANT;

     This is very important when you use MySQL storage engines such as
     `MyISAM' that has only table-level locking (multiple readers with
     single writers). This also gives better performance with most
     database systems, because the row locking manager in this case has
     less to do.

   * If you need to collect statistics from large log tables, use
     summary tables instead of scanning the entire log table.
     Maintaining the summaries should be much faster than trying to
     calculate statistics `live.' Regenerating new summary tables from
     the logs when things change (depending on business decisions) is
     faster than changing the running application.

   * If possible, you should classify reports as `live' or as
     `statistical,' where data needed for statistical reports is
     created only from summary tables that are generated periodically
     from the live data.

   * Take advantage of the fact that columns have default values.
     Insert values explicitly only when the value to be inserted
     differs from the default. This reduces the parsing that MySQL must
     do and improves the insert speed.

   * In some cases, it is convenient to pack and store data into a
     `BLOB' column. In this case, you must provide code in your
     application to pack and unpack information, but this may save a
     lot of accesses at some stage. This is practical when you have
     data that does not conform well to a rows-and-columns table
     structure.

   * Normally, you should try to keep all data non-redundant (observing
     what is referred to in database theory as _third normal form_).
     However, there may be situations in which it can be advantageous to
     duplicate information or create summary tables to gain more speed.

   * Stored routines or UDFs (user-defined functions) may be a good way
     to gain performance for some tasks. See *Note stored-procedures::,
     and *Note adding-functions::, for more information.

   * You can increase performance by caching queries or answers in your
     application and then executing many inserts or updates together.
     If your database system supports table locks, this should help to
     ensure that the index cache is only flushed once after all
     updates. You can also take advantage of MySQL's query cache to
     achieve similar results; see *Note query-cache::.

   * Use `INSERT DELAYED' when you do not need to know when your data
     is written. This reduces the overall insertion impact because many
     rows can be written with a single disk write.

   * Use `INSERT LOW_PRIORITY' when you want to give `SELECT'
     statements higher priority than your inserts.

     Use `SELECT HIGH_PRIORITY' to get retrievals that jump the queue.
     That is, the `SELECT' is executed even if there is another client
     waiting to do a write.

     `LOW_PRIORITY' and `HIGH_PRIORITY' have an effect only for storage
     engines that use only table-level locking (`MyISAM', `MEMORY',
     `MERGE').

   * Use multiple-row `INSERT' statements to store many rows with one
     SQL statement. Many SQL servers support this, including MySQL.

   * Use `LOAD DATA INFILE' to load large amounts of data. This is
     faster than using `INSERT' statements.

   * Use `AUTO_INCREMENT' columns so that each row in a table can be
     identified by a single unique value.  unique values.

   * Use `OPTIMIZE TABLE' once in a while to avoid fragmentation with
     dynamic-format `MyISAM' tables. See *Note myisam-table-formats::.

   * Use `MEMORY' tables when possible to get more speed. See *Note
     memory-storage-engine::.  `MEMORY' tables are useful for
     non-critical data that is accessed often, such as information
     about the last displayed banner for users who don't have cookies
     enabled in their Web browser. User sessions are another
     alternative available in many Web application environments for
     handling volatile state data.

   * With Web servers, images and other binary assets should normally
     be stored as files. That is, store only a reference to the file
     rather than the file itself in the database.  Most Web servers are
     better at caching files than database contents, so using files is
     generally faster.

   * Columns with identical information in different tables should be
     declared to have identical data types so that joins based on the
     corresponding columns will be faster.

   * Try to keep column names simple. For example, in a table named
     `customer', use a column name of `name' instead of
     `customer_name'. To make your names portable to other SQL servers,
     you should keep them shorter than 18 characters.

   * If you need really high speed, you should take a look at the
     low-level interfaces for data storage that the different SQL
     servers support. For example, by accessing the MySQL `MyISAM'
     storage engine directly, you could get a speed increase of two to
     five times compared to using the SQL interface. To be able to do
     this, the data must be on the same server as the application, and
     usually it should only be accessed by one process (because
     external file locking is really slow). One could eliminate these
     problems by introducing low-level `MyISAM' commands in the MySQL
     server (this could be one easy way to get more performance if
     needed). By carefully designing the database interface, it should
     be quite easy to support this type of optimization.

   * If you are using numerical data, it is faster in many cases to
     access information from a database (using a live connection) than
     to access a text file. Information in the database is likely to be
     stored in a more compact format than in the text file, so
     accessing it involves fewer disk accesses. You also save code in
     your application because you need not parse your text files to
     find line and column boundaries.

   * Replication can provide a performance benefit for some operations.
     You can distribute client retrievals among replication servers to
     split up the load. To avoid slowing down the master while making
     backups, you can make backups using a slave server. See *Note
     replication::.

   * Declaring a `MyISAM' table with the `DELAY_KEY_WRITE=1' table
     option makes index updates faster because they are not flushed to
     disk until the table is closed. The downside is that if something
     kills the server while such a table is open, you should ensure
     that the table is okay by running the server with the
     `--myisam-recover' option, or by running `myisamchk' before
     restarting the server.  (However, even in this case, you should
     not lose anything by using `DELAY_KEY_WRITE', because the key
     information can always be generated from the data rows.)


File: manual.info,  Node: locking-issues,  Next: optimizing-database-structure,  Prev: query-speed,  Up: optimization

7.3 Locking Issues
==================

* Menu:

* internal-locking::             Internal Locking Methods
* table-locking::                Table Locking Issues
* concurrent-inserts::           Concurrent Inserts
* external-locking::             External Locking

MySQL manages contention for table contents using locking:

   * Internal locking is performed within the MySQL server itself to
     manage contention for table contents by multiple threads.  This
     type of locking is internal because it is performed entirely by
     the server and involves no other programs. See *Note
     internal-locking::.

   * External locking occurs when the server and other programs lock
     table files to coordinate among themselves which program can
     access the tables at which time. See *Note external-locking::. See
     *Note external-locking::.


File: manual.info,  Node: internal-locking,  Next: table-locking,  Prev: locking-issues,  Up: locking-issues

7.3.1 Internal Locking Methods
------------------------------

This section discusses internal locking; that is, locking performed
within the MySQL server itself to manage contention for table contents
by multiple threads. This type of locking is internal because it is
performed entirely by the server and involves no other programs.
External locking occurs when the server and other programs lock table
files to coordinate among themselves which program can access the
tables at which time.  See *Note external-locking::.

MySQL uses table-level locking for `MyISAM' and `MEMORY' tables, and
row-level locking for `InnoDB' tables.

In many cases, you can make an educated guess about which locking type
is best for an application, but generally it is difficult to say that a
given lock type is better than another.  Everything depends on the
application and different parts of an application may require different
lock types.

To decide whether you want to use a storage engine with row-level
locking, you should look at what your application does and what mix of
select and update statements it uses. For example, most Web
applications perform many selects, relatively few deletes, updates
based mainly on key values, and inserts into a few specific tables. The
base MySQL `MyISAM' setup is very well tuned for this.

MySQL Enterprise

The MySQL Enterprise Monitor provides expert advice on when to use
table-level locking and when to use row-level locking. To subscribe see
`http://www.mysql.com/products/enterprise/advisors.html'.

Table locking in MySQL is deadlock-free for storage engines that use
table-level locking. Deadlock avoidance is managed by always requesting
all needed locks at once at the beginning of a query and always locking
the tables in the same order.

MySQL grants table write locks as follows:

  1. If there are no locks on the table, put a write lock on it.

  2. Otherwise, put the lock request in the write lock queue.

MySQL grants table read locks as follows:

  1. If there are no write locks on the table, put a read lock on it.

  2. Otherwise, put the lock request in the read lock queue.

When a lock is released, the lock is made available to the requests in
the write lock queue and then to the requests in the read lock queue.
This means that if you have many updates for a table, `SELECT'
statements wait until there are no more updates.

You can analyze the table lock contention on your system by checking
the `Table_locks_immediate' and `Table_locks_waited' status variables,
which indicate the number of times that requests for table locks could
be granted immediately and the number that had to wait, respectively:

     mysql> SHOW STATUS LIKE 'Table%';
     +-----------------------+---------+
     | Variable_name         | Value   |
     +-----------------------+---------+
     | Table_locks_immediate | 1151552 |
     | Table_locks_waited    | 15324   |
     +-----------------------+---------+

The `MyISAM' storage engine supports concurrent inserts to reduce
contention between readers and writers for a given table: If a `MyISAM'
table has no free blocks in the middle of the data file, rows are
always inserted at the end of the data file. In this case, you can
freely mix concurrent `INSERT' and `SELECT' statements for a `MyISAM'
table without locks. That is, you can insert rows into a `MyISAM' table
at the same time other clients are reading from it. Holes can result
from rows having been deleted from or updated in the middle of the
table. If there are holes, concurrent inserts are disabled but are
re-enabled automatically when all holes have been filled with new
data.. This behavior is altered by the `concurrent_insert' system
variable. See *Note concurrent-inserts::.

If you acquire a table lock explicitly with `LOCK TABLES', you can
request a `READ LOCAL' lock rather than a `READ' lock to enable other
sessions to perform concurrent inserts while you have the table locked.

To perform many `INSERT' and `SELECT' operations on a table
`real_table' when concurrent inserts are not possible, you can insert
rows into a temporary table `temp_table' and update the real table with
the rows from the temporary table periodically. This can be done with
the following code:

     mysql> LOCK TABLES real_table WRITE, temp_table WRITE;
     mysql> INSERT INTO real_table SELECT * FROM temp_table;
     mysql> DELETE FROM temp_table;
     mysql> UNLOCK TABLES;

`InnoDB' uses row locks. Deadlocks are possible for `InnoDB' because it
automatically acquires locks during the processing of SQL statements,
not at the start of the transaction.

Advantages of row-level locking:

   * Fewer lock conflicts when different sessions access different rows

   * Fewer changes for rollbacks

   * Possible to lock a single row for a long time

Disadvantages of row-level locking:

   * Requires more memory than table-level locks

   * Slower than table-level locks when used on a large part of the
     table because you must acquire many more locks

   * Definitely much slower than other locks if you often do `GROUP BY'
     operations on a large part of the data or if you must scan the
     entire table frequently

Table locks are superior to row-level locks in the following cases:

   * Most statements for the table are reads

   * Statements for the table are a mix of reads and writes, where
     writes are updates or deletes for a single row that can be fetched
     with one key read:

          UPDATE TBL_NAME SET COLUMN=VALUE WHERE UNIQUE_KEY_COL=KEY_VALUE;
          DELETE FROM TBL_NAME WHERE UNIQUE_KEY_COL=KEY_VALUE;

   * `SELECT' combined with concurrent `INSERT' statements, and very few
     `UPDATE' or `DELETE' statements

   * Many scans or `GROUP BY' operations on the entire table without
     any writers

With higher-level locks, you can more easily tune applications by
supporting locks of different types, because the lock overhead is less
than for row-level locks.

Options other than row-level locking:

   * Versioning (such as that used in MySQL for concurrent inserts)
     where it is possible to have one writer at the same time as many
     readers. This means that the database or table supports different
     views for the data depending on when access begins. Other common
     terms for this are `time travel,' `copy on write,' or `copy on
     demand.'

   * Copy on demand is in many cases superior to row-level locking.
     However, in the worst case, it can use much more memory than using
     normal locks.

   * Instead of using row-level locks, you can employ application-level
     locks, such as those provided by `GET_LOCK()' and `RELEASE_LOCK()'
     in MySQL.  These are advisory locks, so they work only with
     applications that cooperate with each other. See *Note
     miscellaneous-functions::.


File: manual.info,  Node: table-locking,  Next: concurrent-inserts,  Prev: internal-locking,  Up: locking-issues

7.3.2 Table Locking Issues
--------------------------

To achieve a very high lock speed, MySQL uses table locking (instead of
page, row, or column locking) for all storage engines except `InnoDB'
and `NDBCLUSTER'.

For `InnoDB' tables, MySQL only uses table locking if you explicitly
lock the table with `LOCK TABLES'. For these storage engines, we
recommend that you not use `LOCK TABLES' at all, because `InnoDB' uses
automatic row-level locking to ensure transaction isolation.

For large tables, table locking is much better than row locking for
most applications, but there are some pitfalls:

   * Table locking enables many threads to read from a table at the
     same time, but if a thread wants to write to a table, it must
     first get exclusive access. During the update, all other threads
     that want to access this particular table must wait until the
     update is done.

   * Table updates normally are considered to be more important than
     table retrievals, so they are given higher priority.  This should
     ensure that updates to a table are not `starved' even if there is
     heavy `SELECT' activity for the table.

   * Table locking causes problems in cases such as when a thread is
     waiting because the disk is full and free space needs to become
     available before the thread can proceed. In this case, all threads
     that want to access the problem table are also put in a waiting
     state until more disk space is made available.

Table locking is also disadvantageous under the following scenario:

   * A client issues a `SELECT' that takes a long time to run.

   * Another client then issues an `UPDATE' on the same table. This
     client waits until the `SELECT' is finished.

   * Another client issues another `SELECT' statement on the same
     table. Because `UPDATE' has higher priority than `SELECT', this
     `SELECT' waits for the `UPDATE' to finish, _and_ for the first
     `SELECT' to finish.

The following items describe some ways to avoid or reduce contention
caused by table locking:

   * Try to get the `SELECT' statements to run faster so that they lock
     tables for a shorter time. You might have to create some summary
     tables to do this.

   * Start `mysqld' with `--low-priority-updates'. For storage engines
     that use only table-level locking (`MyISAM', `MEMORY', `MERGE'),
     this gives all statements that update (modify) a table lower
     priority than `SELECT' statements. In this case, the second
     `SELECT' statement in the preceding scenario would execute before
     the `UPDATE' statement, and would not need to wait for the first
     `SELECT' to finish.

   * You can specify that all updates issued in a specific connection
     should be done with low priority by using the `SET
     LOW_PRIORITY_UPDATES=1' statement. See *Note
     server-session-variables::.

   * You can give a specific `INSERT', `UPDATE', or `DELETE' statement
     lower priority with the `LOW_PRIORITY' attribute.

   * You can give a specific `SELECT' statement higher priority with
     the `HIGH_PRIORITY' attribute. See *Note select::.

   * You can start `mysqld' with a low value for the
     `max_write_lock_count' system variable to force MySQL to
     temporarily elevate the priority of all `SELECT' statements that
     are waiting for a table after a specific number of inserts to the
     table occur.  This allows `READ' locks after a certain number of
     `WRITE' locks.

   * If you have problems with `INSERT' combined with `SELECT', you
     might want to consider switching to `MyISAM' tables, which support
     concurrent `SELECT' and `INSERT' statements. (See *Note
     concurrent-inserts::.)

   * If you mix inserts and deletes on the same table, `INSERT DELAYED'
     may be of great help. See *Note insert-delayed::.

   * If you have problems with mixed `SELECT' and `DELETE' statements,
     the `LIMIT' option to `DELETE' may help. See *Note delete::.

   * Using `SQL_BUFFER_RESULT' with `SELECT' statements can help to
     make the duration of table locks shorter. See *Note select::.

   * You could change the locking code in `mysys/thr_lock.c' to use a
     single queue.  In this case, write locks and read locks would have
     the same priority, which might help some applications.

Here are some tips concerning table locks in MySQL:

   * Concurrent users are not a problem if you do not mix updates with
     selects that need to examine many rows in the same table.

   * You can use `LOCK TABLES' to increase speed, because many updates
     within a single lock is much faster than updating without locks.
     Splitting table contents into separate tables may also help.

   * If you encounter speed problems with table locks in MySQL, you may
     be able to improve performance by converting some of your tables
     to `InnoDB'. See *Note innodb::.

     MySQL Enterprise

     Lock contention can seriously degrade performance. The MySQL
     Enterprise Monitor provides expert advice on avoiding this
     problem. To subscribe, see
     `http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: concurrent-inserts,  Next: external-locking,  Prev: table-locking,  Up: locking-issues

7.3.3 Concurrent Inserts
------------------------

The `MyISAM' storage engine supports concurrent inserts to reduce
contention between readers and writers for a given table: If a `MyISAM'
table has no holes in the data file (deleted rows in the middle),
inserts can be performed to add rows to the end of the table at the
same time that `SELECT' statements are reading rows from the table.

The `concurrent_insert' system variable can be set to modify the
concurrent-insert processing. By default, the variable is set to 1 and
concurrent inserts are handled as just described. If
`concurrent_insert' is set to 0, concurrent inserts are disabled. If
the variable is set to 2, concurrent inserts at the end of the table
are allowed even for tables that have deleted rows. See also the
description of the `concurrent_insert' system variable.

Under circumstances where concurrent inserts can be used, there is
seldom any need to use the `DELAYED' modifier for `INSERT' statements.
See *Note insert-delayed::.

If you are using the binary log, concurrent inserts are converted to
normal inserts for `CREATE ...  SELECT' or `INSERT ... SELECT'
statements. This is done to ensure that you can re-create an exact copy
of your tables by applying the log during a backup operation. See *Note
binary-log::. In addition, for those statements a read lock is placed
on the selected-from table such that inserts into that table are
blocked. The effect is that concurrent inserts for that table must wait
as well.

With `LOAD DATA INFILE', if you specify `CONCURRENT' with a `MyISAM'
table that satisfies the condition for concurrent inserts (that is, it
contains no free blocks in the middle), other threads can retrieve data
from the table while `LOAD DATA' is executing. Use of the `CONCURRENT'
option affects the performance of `LOAD DATA' a bit, even if no other
thread is using the table at the same time.

If you specify `HIGH_PRIORITY', it overrides the effect of the
`--low-priority-updates' option if the server was started with that
option. It also causes concurrent inserts not to be used.

For `LOCK TABLE', the difference between `READ LOCAL' and `READ' is
that `READ LOCAL' allows non-conflicting `INSERT' statements
(concurrent inserts) to execute while the lock is held. However, this
cannot be used if you are going to manipulate the database using
processes external to the server while you hold the lock.


File: manual.info,  Node: external-locking,  Prev: concurrent-inserts,  Up: locking-issues

7.3.4 External Locking
----------------------

External locking is the use of filesystem locking to manage contention
for database tables by multiple processes. External locking is used in
situations where a single process such as the MySQL server cannot be
assumed to be the only process that requires access to tables. Here are
some examples:

   * If you run multiple servers that use the same database directory
     (not recommended), each server must have external locking enabled.

   * If you use `myisamchk' to perform table maintenance operations on
     `MyISAM' tables, you must either ensure that the server is not
     running, or that the server has external locking enabled so that it
     locks table files as necessary to coordinate with `myisamchk' for
     access to the tables. The same is true for use of `myisampack' to
     pack `MyISAM' tables.

With external locking in effect, each process that requires access to a
table acquires a filesystem lock for the table files before proceeding
to access the table. If all necessary locks cannot be acquired, the
process is blocked from accessing the table until the locks can be
obtained (after the process that currently holds the locks releases
them).

External locking affects server performance because the server must
sometimes wait for other processes before it can access tables.

External locking is unnecessary if you run a single server to access a
given data directory (which is the usual case) and if no other programs
such as `myisamchk' need to modify tables while the server is running.
If you only _read_ tables with other programs, external locking is not
required, although `myisamchk' might report warnings if the server
changes tables while `myisamchk' is reading them.

With external locking disabled, to use `myisamchk', you must either
stop the server while `myisamchk' executes or else lock and flush the
tables before running `myisamchk'.  (See *Note system-optimization::.)
To avoid this requirement, use the `CHECK TABLE' and `REPAIR TABLE'
statements to check and repair `MyISAM' tables.

For `mysqld', external locking is controlled by the value of the
`skip_external_locking' system variable. (Before MySQL 4.0.3, this
variable is named `skip_locking'.) When this variable is enabled,
external locking is disabled, and vice versa. From MySQL 4.0 on,
external locking is disabled by default. Before MySQL 4.0, external
locking is enabled by default on Linux or when MySQL is configured to
use MIT-pthreads.

Use of external locking can be controlled at server startup by using
the `--external-locking' or `--skip-external-locking' option. (Before
MySQL 4.0.3, these options are named `--enable-locking' and
`--skip-locking'.)

If you do use external locking option to enable updates to `MyISAM'
tables from many MySQL processes, you must ensure that the following
conditions are satisfied:

   * You should not use the query cache for queries that use tables
     that are updated by another process.

   * You should not start the server with the `--delay-key-write=ALL'
     option or use the `DELAY_KEY_WRITE=1' table option for any shared
     tables. Otherise, index corruption can occur.

The easiest way to satisfy these conditions is to always use
`--external-locking' together with `--delay-key-write=OFF' and
`--query-cache-size=0'. (This is not done by default because in many
setups it is useful to have a mixture of the preceding options.)


File: manual.info,  Node: optimizing-database-structure,  Next: optimizing-the-server,  Prev: locking-issues,  Up: optimization

7.4 Optimizing Database Structure
=================================

* Menu:

* design::                       Design Choices
* data-size::                    Make Your Data as Small as Possible
* indexes::                      Column Indexes
* multiple-column-indexes::      Multiple-Column Indexes
* mysql-indexes::                How MySQL Uses Indexes
* myisam-key-cache::             The `MyISAM' Key Cache
* myisam-index-statistics::      `MyISAM' Index Statistics Collection
* table-cache::                  How MySQL Opens and Closes Tables
* creating-many-tables::         Drawbacks to Creating Many Tables in the Same Database


File: manual.info,  Node: design,  Next: data-size,  Prev: optimizing-database-structure,  Up: optimizing-database-structure

7.4.1 Design Choices
--------------------

MySQL keeps row data and index data in separate files. Many (almost
all) other database systems mix row and index data in the same file. We
believe that the MySQL choice is better for a very wide range of modern
systems.

Another way to store the row data is to keep the information for each
column in a separate area (examples are SDBM and Focus).  This causes a
performance hit for every query that accesses more than one column.
Because this degenerates so quickly when more than one column is
accessed, we believe that this model is not good for general-purpose
databases.

The more common case is that the index and data are stored together (as
in Oracle/Sybase, et al). In this case, you find the row information at
the leaf page of the index. The good thing with this layout is that it,
in many cases, depending on how well the index is cached, saves a disk
read. The bad things with this layout are:

   * Table scanning is much slower because you have to read through the
     indexes to get at the data.

   * You cannot use only the index table to retrieve data for a query.

   * You use more space because you must duplicate indexes from the
     nodes (you cannot store the row in the nodes).

   * Deletes degenerate the table over time (because indexes in nodes
     are usually not updated on delete).

   * It is more difficult to cache only the index data.


File: manual.info,  Node: data-size,  Next: indexes,  Prev: design,  Up: optimizing-database-structure

7.4.2 Make Your Data as Small as Possible
-----------------------------------------

One of the most basic optimizations is to design your tables to take as
little space on the disk as possible. This can result in huge
improvements because disk reads are faster, and smaller tables normally
require less main memory while their contents are being actively
processed during query execution. Indexing also is a lesser resource
burden if done on smaller columns.

MySQL supports many different storage engines (table types) and row
formats. For each table, you can decide which storage and indexing
method to use. Choosing the proper table format for your application
may give you a big performance gain. See *Note storage-engines::.

You can get better performance for a table and minimize storage space
by using the techniques listed here:

   * Use the most efficient (smallest) data types possible. MySQL has
     many specialized types that save disk space and memory.  For
     example, use the smaller integer types if possible to get smaller
     tables. `MEDIUMINT' is often a better choice than `INT' because a
     `MEDIUMINT' column uses 25% less space.

   * Declare columns to be `NOT NULL' if possible. It makes everything
     faster and you save one bit per column. If you really need `NULL'
     in your application, you should definitely use it. Just avoid
     having it on all columns by default.

   * For `MyISAM' tables, if you do not have any variable-length
     columns (`VARCHAR', `TEXT', or `BLOB' columns), a fixed-size row
     format is used. This is faster but unfortunately may waste some
     space. See *Note myisam-table-formats::. You can hint that you
     want to have fixed length rows even if you have `VARCHAR' columns
     with the `CREATE TABLE' option `ROW_FORMAT=FIXED'.

   * `InnoDB' tables use a compact storage format. In versions of MySQL
     earlier than 5.0.3, `InnoDB' rows contain some redundant
     information, such as the number of columns and the length of each
     column, even for fixed-size columns. By default, tables are
     created in the compact format (`ROW_FORMAT=COMPACT'). If you wish
     to downgrade to older versions of MySQL, you can request the old
     format with `ROW_FORMAT=REDUNDANT'.

     The presence of the compact row format decreases row storage space
     by about 20% at the cost of increasing CPU use for some
     operations. If your workload is a typical one that is limited by
     cache hit rates and disk speed it is likely to be faster. If it is
     a rare case that is limited by CPU speed, it might be slower.

     The compact `InnoDB' format also changes how `CHAR' columns
     containing UTF-8 data are stored. With `ROW_FORMAT=REDUNDANT', a
     UTF-8 `CHAR(N)' occupies 3 x N bytes, given that the maximum
     length of a UTF-8 encoded character is three bytes. Many languages
     can be written primarily using single-byte UTF-8 characters, so a
     fixed storage length often wastes space. With `ROW_FORMAT=COMPACT'
     format, `InnoDB' allocates a variable amount of storage in the
     range from N to 3 x N bytes for these columns by stripping
     trailing spaces if necessary. The minimum storage length is kept
     as N bytes to facilitate in-place updates in typical cases.

   * The primary index of a table should be as short as possible.  This
     makes identification of each row easy and efficient.

   * Create only the indexes that you really need. Indexes are good for
     retrieval but bad when you need to store data quickly. If you
     access a table mostly by searching on a combination of columns,
     create an index on them. The first part of the index should be the
     column most used. If you _always_ use many columns when selecting
     from the table, you should use the column with more duplicates
     first to obtain better compression of the index.

   * If it is very likely that a string column has a unique prefix on
     the first number of characters, it's better to index only this
     prefix, using MySQL's support for creating an index on the
     leftmost part of the column (see *Note create-index::). Shorter
     indexes are faster, not only because they require less disk space,
     but because they also give you more hits in the index cache, and
     thus fewer disk seeks. See *Note server-parameters::.

   * In some circumstances, it can be beneficial to split into two a
     table that is scanned very often. This is especially true if it is
     a dynamic-format table and it is possible to use a smaller static
     format table that can be used to find the relevant rows when
     scanning the table.


File: manual.info,  Node: indexes,  Next: multiple-column-indexes,  Prev: data-size,  Up: optimizing-database-structure

7.4.3 Column Indexes
--------------------

All MySQL data types can be indexed. Use of indexes on the relevant
columns is the best way to improve the performance of `SELECT'
operations.

The maximum number of indexes per table and the maximum index length is
defined per storage engine. See *Note storage-engines::. All storage
engines support at least 16 indexes per table and a total index length
of at least 256 bytes. Most storage engines have higher limits.

With `COL_NAME(N)' syntax in an index specification, you can create an
index that uses only the first N characters of a string column.
Indexing only a prefix of column values in this way can make the index
file much smaller. When you index a `BLOB' or `TEXT' column, you _must_
specify a prefix length for the index.  For example:

     CREATE TABLE test (blob_col BLOB, INDEX(blob_col(10)));

Prefixes can be up to 1000 bytes long (767 bytes for `InnoDB' tables).
Note that prefix limits are measured in bytes, whereas the prefix
length in `CREATE TABLE' statements is interpreted as number of
characters. _Be sure to take this into account when specifying a prefix
length for a column that uses a multi-byte character set_.

You can also create `FULLTEXT' indexes. These are used for full-text
searches. Only the `MyISAM' storage engine supports `FULLTEXT' indexes
and only for `CHAR', `VARCHAR', and `TEXT' columns. Indexing always
takes place over the entire column and column prefix indexing is not
supported. For details, see *Note fulltext-search::.

You can also create indexes on spatial data types. Currently, only
`MyISAM' supports R-tree indexes on spatial types. Other storage
engines use B-trees for indexing spatial types (except for `ARCHIVE' and
`NDBCLUSTER', which do not support spatial type indexing).

The `MEMORY' storage engine uses `HASH' indexes by default, but also
supports `BTREE' indexes.


File: manual.info,  Node: multiple-column-indexes,  Next: mysql-indexes,  Prev: indexes,  Up: optimizing-database-structure

7.4.4 Multiple-Column Indexes
-----------------------------

MySQL can create composite indexes (that is, indexes on multiple
columns). An index may consist of up to 15 columns. For certain data
types, you can index a prefix of the column (see *Note indexes::).

A multiple-column index can be considered a sorted array containing
values that are created by concatenating the values of the indexed
columns.

MySQL uses multiple-column indexes in such a way that queries are fast
when you specify a known quantity for the first column of the index in
a `WHERE' clause, even if you do not specify values for the other
columns.

Suppose that a table has the following specification:

     CREATE TABLE test (
         id         INT NOT NULL,
         last_name  CHAR(30) NOT NULL,
         first_name CHAR(30) NOT NULL,
         PRIMARY KEY (id),
         INDEX name (last_name,first_name)
     );

The `name' index is an index over the `last_name' and `first_name'
columns. The index can be used for queries that specify values in a
known range for `last_name', or for both `last_name' and `first_name'.
Therefore, the `name' index is used in the following queries:

     SELECT * FROM test WHERE last_name='Widenius';

     SELECT * FROM test
       WHERE last_name='Widenius' AND first_name='Michael';

     SELECT * FROM test
       WHERE last_name='Widenius'
       AND (first_name='Michael' OR first_name='Monty');

     SELECT * FROM test
       WHERE last_name='Widenius'
       AND first_name >='M' AND first_name < 'N';

However, the `name' index is _not_ used in the following queries:

     SELECT * FROM test WHERE first_name='Michael';

     SELECT * FROM test
       WHERE last_name='Widenius' OR first_name='Michael';

The manner in which MySQL uses indexes to improve query performance is
discussed further in *Note mysql-indexes::.


File: manual.info,  Node: mysql-indexes,  Next: myisam-key-cache,  Prev: multiple-column-indexes,  Up: optimizing-database-structure

7.4.5 How MySQL Uses Indexes
----------------------------

Indexes are used to find rows with specific column values quickly.
Without an index, MySQL must begin with the first row and then read
through the entire table to find the relevant rows. The larger the
table, the more this costs. If the table has an index for the columns
in question, MySQL can quickly determine the position to seek to in the
middle of the data file without having to look at all the data. If a
table has 1,000 rows, this is at least 100 times faster than reading
sequentially. If you need to access most of the rows, it is faster to
read sequentially, because this minimizes disk seeks.

Most MySQL indexes (`PRIMARY KEY', `UNIQUE', `INDEX', and `FULLTEXT')
are stored in B-trees. Exceptions are that indexes on spatial data
types use R-trees, and that `MEMORY' tables also support hash indexes.

Strings are automatically prefix- and end-space compressed. See *Note
create-index::.

In general, indexes are used as described in the following discussion.
Characteristics specific to hash indexes (as used in `MEMORY' tables)
are described at the end of this section.

MySQL uses indexes for these operations:

   * To find the rows matching a `WHERE' clause quickly.

   * To eliminate rows from consideration. If there is a choice between
     multiple indexes, MySQL normally uses the index that finds the
     smallest number of rows.

   * To retrieve rows from other tables when performing joins.  MySQL
     can use indexes on columns more efficiently if they are declared
     as the same type and size. In this context, `VARCHAR' and `CHAR'
     are considered the same if they are declared as the same size.
     For example, `VARCHAR(10)' and `CHAR(10)' are the same size, but
     `VARCHAR(10)' and `CHAR(15)' are not.

     Comparison of dissimilar columns may prevent use of indexes if
     values cannot be compared directly without conversion.  Suppose
     that a numeric column is compared to a string column. For a given
     value such as `1' in the numeric column, it might compare equal to
     any number of values in the string column such as `'1'', `' 1'',
     `'00001'', or `'01.e1''. This rules out use of any indexes for the
     string column.

   * To find the `MIN()' or `MAX()' value for a specific indexed column
     KEY_COL. This is optimized by a preprocessor that checks whether
     you are using `WHERE KEY_PART_N = CONSTANT' on all key parts that
     occur before KEY_COL in the index. In this case, MySQL does a
     single key lookup for each `MIN()' or `MAX()' expression and
     replaces it with a constant. If all expressions are replaced with
     constants, the query returns at once. For example:

          SELECT MIN(KEY_PART2),MAX(KEY_PART2)
            FROM TBL_NAME WHERE KEY_PART1=10;

   * To sort or group a table if the sorting or grouping is done on a
     leftmost prefix of a usable key (for example, `ORDER BY KEY_PART1,
     KEY_PART2'). If all key parts are followed by `DESC', the key is
     read in reverse order. See *Note order-by-optimization::.

   * In some cases, a query can be optimized to retrieve values without
     consulting the data rows. If a query uses only columns from a
     table that are numeric and that form a leftmost prefix for some
     key, the selected values may be retrieved from the index tree for
     greater speed:

          SELECT KEY_PART3 FROM TBL_NAME
            WHERE KEY_PART1=1

Suppose that you issue the following `SELECT' statement:

     mysql> SELECT * FROM TBL_NAME WHERE col1=VAL1 AND col2=VAL2;

If a multiple-column index exists on `col1' and `col2', the appropriate
rows can be fetched directly. If separate single-column indexes exist on
`col1' and `col2', the optimizer will attempt to use the Index Merge
optimization (see *Note index-merge-optimization::), or attempt to find
the most restrictive index by deciding which index finds fewer rows and
using that index to fetch the rows.

If the table has a multiple-column index, any leftmost prefix of the
index can be used by the optimizer to find rows. For example, if you
have a three-column index on `(col1, col2, col3)', you have indexed
search capabilities on `(col1)', `(col1, col2)', and `(col1, col2,
col3)'.

MySQL cannot use an index if the columns do not form a leftmost prefix
of the index. Suppose that you have the `SELECT' statements shown here:

     SELECT * FROM TBL_NAME WHERE col1=VAL1;
     SELECT * FROM TBL_NAME WHERE col1=VAL1 AND col2=VAL2;

     SELECT * FROM TBL_NAME WHERE col2=VAL2;
     SELECT * FROM TBL_NAME WHERE col2=VAL2 AND col3=VAL3;

If an index exists on `(col1, col2, col3)', only the first two queries
use the index. The third and fourth queries do involve indexed columns,
but `(col2)' and `(col2, col3)' are not leftmost prefixes of `(col1,
col2, col3)'.

A B-tree index can be used for column comparisons in expressions that
use the `=', `>', `>=', `<', `<=', or `BETWEEN' operators. The index
also can be used for `LIKE' comparisons if the argument to `LIKE' is a
constant string that does not start with a wildcard character. For
example, the following `SELECT' statements use indexes:

     SELECT * FROM TBL_NAME WHERE KEY_COL LIKE 'Patrick%';
     SELECT * FROM TBL_NAME WHERE KEY_COL LIKE 'Pat%_ck%';

In the first statement, only rows with `'Patrick' <= KEY_COL <
'Patricl'' are considered. In the second statement, only rows with
`'Pat' <= KEY_COL < 'Pau'' are considered.

The following `SELECT' statements do not use indexes:

     SELECT * FROM TBL_NAME WHERE KEY_COL LIKE '%Patrick%';
     SELECT * FROM TBL_NAME WHERE KEY_COL LIKE OTHER_COL;

In the first statement, the `LIKE' value begins with a wildcard
character. In the second statement, the `LIKE' value is not a constant.

If you use `... LIKE '%STRING%'' and STRING is longer than three
characters, MySQL uses the _Turbo Boyer-Moore algorithm_ to initialize
the pattern for the string and then uses this pattern to perform the
search more quickly.

A search using `COL_NAME IS NULL' employs indexes if COL_NAME is
indexed.

Any index that does not span all `AND' levels in the `WHERE' clause is
not used to optimize the query. In other words, to be able to use an
index, a prefix of the index must be used in every `AND' group.

The following `WHERE' clauses use indexes:

     ... WHERE INDEX_PART1=1 AND INDEX_PART2=2 AND OTHER_COLUMN=3
         /* INDEX = 1 OR INDEX = 2 */
     ... WHERE INDEX=1 OR A=10 AND INDEX=2
         /* optimized like "INDEX_PART1='hello'" */
     ... WHERE INDEX_PART1='hello' AND INDEX_PART3=5
         /* Can use index on INDEX1 but not on INDEX2 or INDEX3 */
     ... WHERE INDEX1=1 AND INDEX2=2 OR INDEX1=3 AND INDEX3=3;

These `WHERE' clauses do _not_ use indexes:

         /* INDEX_PART1 is not used */
     ... WHERE INDEX_PART2=1 AND INDEX_PART3=2

         /*  Index is not used in both parts of the WHERE clause  */
     ... WHERE INDEX=1 OR A=10

         /* No index spans all rows  */
     ... WHERE INDEX_PART1=1 OR INDEX_PART2=10

Sometimes MySQL does not use an index, even if one is available.  One
circumstance under which this occurs is when the optimizer estimates
that using the index would require MySQL to access a very large
percentage of the rows in the table. (In this case, a table scan is
likely to be much faster because it requires fewer seeks.) However, if
such a query uses `LIMIT' to retrieve only some of the rows, MySQL uses
an index anyway, because it can much more quickly find the few rows to
return in the result.

Hash indexes have somewhat different characteristics from those just
discussed:

   * They are used only for equality comparisons that use the `=' or
     `<=>' operators (but are _very_ fast). They are not used for
     comparison operators such as `<' that find a range of values.

   * The optimizer cannot use a hash index to speed up `ORDER BY'
     operations. (This type of index cannot be used to search for the
     next entry in order.)

   * MySQL cannot determine approximately how many rows there are
     between two values (this is used by the range optimizer to decide
     which index to use). This may affect some queries if you change a
     `MyISAM' table to a hash-indexed `MEMORY' table.

   * Only whole keys can be used to search for a row. (With a B-tree
     index, any leftmost prefix of the key can be used to find rows.)

MySQL Enterprise

Often, it is not possible to predict exactly what indexes will be
required or will be most efficient -- actual table usage is the best
indicator. The MySQL Enterprise Monitor provides expert advice on this
topic. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: myisam-key-cache,  Next: myisam-index-statistics,  Prev: mysql-indexes,  Up: optimizing-database-structure

7.4.6 The `MyISAM' Key Cache
----------------------------

* Menu:

* shared-key-cache::             Shared Key Cache Access
* multiple-key-caches::          Multiple Key Caches
* midpoint-insertion::           Midpoint Insertion Strategy
* index-preloading::             Index Preloading
* key-cache-block-size::         Key Cache Block Size
* key-cache-restructuring::      Restructuring a Key Cache

To minimize disk I/O, the `MyISAM' storage engine exploits a strategy
that is used by many database management systems. It employs a cache
mechanism to keep the most frequently accessed table blocks in memory:

   * For index blocks, a special structure called the _key cache_ (or
     _key buffer_) is maintained. The structure contains a number of
     block buffers where the most-used index blocks are placed.

   * For data blocks, MySQL uses no special cache. Instead it relies on
     the native operating system filesystem cache.

This section first describes the basic operation of the `MyISAM' key
cache. Then it discusses features that improve key cache performance
and that enable you to better control cache operation:

   * Multiple threads can access the cache concurrently.

   * You can set up multiple key caches and assign table indexes to
     specific caches.

To control the size of the key cache, use the `key_buffer_size' system
variable. If this variable is set equal to zero, no key cache is used.
The key cache also is not used if the `key_buffer_size' value is too
small to allocate the minimal number of block buffers (8).

MySQL Enterprise

For expert advice on identifying the optimum size for
`key_buffer_size', subscribe to the MySQL Enterprise Monitor. See
`http://www.mysql.com/products/enterprise/advisors.html'.

When the key cache is not operational, index files are accessed using
only the native filesystem buffering provided by the operating system.
(In other words, table index blocks are accessed using the same
strategy as that employed for table data blocks.)

An index block is a contiguous unit of access to the `MyISAM' index
files. Usually the size of an index block is equal to the size of nodes
of the index B-tree.  (Indexes are represented on disk using a B-tree
data structure.  Nodes at the bottom of the tree are leaf nodes. Nodes
above the leaf nodes are non-leaf nodes.)

All block buffers in a key cache structure are the same size.  This
size can be equal to, greater than, or less than the size of a table
index block. Usually one these two values is a multiple of the other.

When data from any table index block must be accessed, the server first
checks whether it is available in some block buffer of the key cache.
If it is, the server accesses data in the key cache rather than on
disk. That is, it reads from the cache or writes into it rather than
reading from or writing to disk.  Otherwise, the server chooses a cache
block buffer containing a different table index block (or blocks) and
replaces the data there by a copy of required table index block. As
soon as the new index block is in the cache, the index data can be
accessed.

If it happens that a block selected for replacement has been modified,
the block is considered `dirty.' In this case, prior to being replaced,
its contents are flushed to the table index from which it came.

Usually the server follows an _LRU (Least Recently Used)_ strategy:
When choosing a block for replacement, it selects the least recently
used index block. To make this choice easier, the key cache module
maintains a special queue (_LRU chain_) of all used blocks. When a
block is accessed, it is placed at the end of the queue. When blocks
need to be replaced, blocks at the beginning of the queue are the least
recently used and become the first candidates for eviction.


File: manual.info,  Node: shared-key-cache,  Next: multiple-key-caches,  Prev: myisam-key-cache,  Up: myisam-key-cache

7.4.6.1 Shared Key Cache Access
...............................

Threads can access key cache buffers simultaneously, subject to the
following conditions:

   * A buffer that is not being updated can be accessed by multiple
     threads.

   * A buffer that is being updated causes threads that need to use it
     to wait until the update is complete.

   * Multiple threads can initiate requests that result in cache block
     replacements, as long as they do not interfere with each other
     (that is, as long as they need different index blocks, and thus
     cause different cache blocks to be replaced).

Shared access to the key cache enables the server to improve throughput
significantly.


File: manual.info,  Node: multiple-key-caches,  Next: midpoint-insertion,  Prev: shared-key-cache,  Up: myisam-key-cache

7.4.6.2 Multiple Key Caches
...........................

Shared access to the key cache improves performance but does not
eliminate contention among threads entirely. They still compete for
control structures that manage access to the key cache buffers. To
reduce key cache access contention further, MySQL also provides
multiple key caches. This feature enables you to assign different table
indexes to different key caches.

Where there are multiple key caches, the server must know which cache
to use when processing queries for a given `MyISAM' table. By default,
all `MyISAM' table indexes are cached in the default key cache. To
assign table indexes to a specific key cache, use the `CACHE INDEX'
statement (see *Note cache-index::). For example, the following
statement assigns indexes from the tables `t1', `t2', and `t3' to the
key cache named `hot_cache':

     mysql> CACHE INDEX t1, t2, t3 IN hot_cache;
     +---------+--------------------+----------+----------+
     | Table   | Op                 | Msg_type | Msg_text |
     +---------+--------------------+----------+----------+
     | test.t1 | assign_to_keycache | status   | OK       |
     | test.t2 | assign_to_keycache | status   | OK       |
     | test.t3 | assign_to_keycache | status   | OK       |
     +---------+--------------------+----------+----------+

The key cache referred to in a `CACHE INDEX' statement can be created
by setting its size with a `SET GLOBAL' parameter setting statement or
by using server startup options. For example:

     mysql> SET GLOBAL keycache1.key_buffer_size=128*1024;

To destroy a key cache, set its size to zero:

     mysql> SET GLOBAL keycache1.key_buffer_size=0;

Note that you cannot destroy the default key cache. Any attempt to do
this will be ignored:

     mysql> SET GLOBAL key_buffer_size = 0;

     mysql> SHOW VARIABLES LIKE 'key_buffer_size';
     +-----------------+---------+
     | Variable_name   | Value   |
     +-----------------+---------+
     | key_buffer_size | 8384512 |
     +-----------------+---------+

Key cache variables are structured system variables that have a name
and components. For `keycache1.key_buffer_size', `keycache1' is the
cache variable name and `key_buffer_size' is the cache component. See
*Note structured-system-variables::, for a description of the syntax
used for referring to structured key cache system variables.

By default, table indexes are assigned to the main (default) key cache
created at the server startup. When a key cache is destroyed, all
indexes assigned to it are reassigned to the default key cache.

For a busy server, we recommend a strategy that uses three key caches:

   * A `hot' key cache that takes up 20% of the space allocated for all
     key caches. Use this for tables that are heavily used for searches
     but that are not updated.

   * A `cold' key cache that takes up 20% of the space allocated for
     all key caches. Use this cache for medium-sized, intensively
     modified tables, such as temporary tables.

   * A `warm' key cache that takes up 60% of the key cache space.
     Employ this as the default key cache, to be used by default for
     all other tables.

One reason the use of three key caches is beneficial is that access to
one key cache structure does not block access to the others. Statements
that access tables assigned to one cache do not compete with statements
that access tables assigned to another cache. Performance gains occur
for other reasons as well:

   * The hot cache is used only for retrieval queries, so its contents
     are never modified. Consequently, whenever an index block needs to
     be pulled in from disk, the contents of the cache block chosen for
     replacement need not be flushed first.

   * For an index assigned to the hot cache, if there are no queries
     requiring an index scan, there is a high probability that the
     index blocks corresponding to non-leaf nodes of the index B-tree
     remain in the cache.

   * An update operation most frequently executed for temporary tables
     is performed much faster when the updated node is in the cache and
     need not be read in from disk first. If the size of the indexes of
     the temporary tables are comparable with the size of cold key
     cache, the probability is very high that the updated node is in the
     cache.

`CACHE INDEX' sets up an association between a table and a key cache,
but the association is lost each time the server restarts. If you want
the association to take effect each time the server starts, one way to
accomplish this is to use an option file: Include variable settings that
configure your key caches, and an `init-file' option that names a file
containing `CACHE INDEX' statements to be executed. For example:

     key_buffer_size = 4G
     hot_cache.key_buffer_size = 2G
     cold_cache.key_buffer_size = 2G
     init_file=/PATH/TO/DATA-DIRECTORY/mysqld_init.sql

MySQL Enterprise

For advice on how best to configure your `my.cnf/my.ini ' option file
subscribe to MySQL Enterprise Monitor. Recommendations are based on
actual table usage. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

The statements in `mysqld_init.sql' are executed each time the server
starts. The file should contain one SQL statement per line. The
following example assigns several tables each to `hot_cache' and
`cold_cache':

     CACHE INDEX db1.t1, db1.t2, db2.t3 IN hot_cache
     CACHE INDEX db1.t4, db2.t5, db2.t6 IN cold_cache


File: manual.info,  Node: midpoint-insertion,  Next: index-preloading,  Prev: multiple-key-caches,  Up: myisam-key-cache

7.4.6.3 Midpoint Insertion Strategy
...................................

By default, the key cache management system uses the LRU strategy for
choosing key cache blocks to be evicted, but it also supports a more
sophisticated method called the _midpoint insertion strategy._

When using the midpoint insertion strategy, the LRU chain is divided
into two parts: a hot sub-chain and a warm sub-chain.  The division
point between two parts is not fixed, but the key cache management
system takes care that the warm part is not `too short,' always
containing at least `key_cache_division_limit' percent of the key cache
blocks. `key_cache_division_limit' is a component of structured key
cache variables, so its value is a parameter that can be set per cache.

When an index block is read from a table into the key cache, it is
placed at the end of the warm sub-chain. After a certain number of hits
(accesses of the block), it is promoted to the hot sub-chain. At
present, the number of hits required to promote a block (3) is the same
for all index blocks.

A block promoted into the hot sub-chain is placed at the end of the
chain. The block then circulates within this sub-chain.  If the block
stays at the beginning of the sub-chain for a long enough time, it is
demoted to the warm chain. This time is determined by the value of the
`key_cache_age_threshold' component of the key cache.

The threshold value prescribes that, for a key cache containing N
blocks, the block at the beginning of the hot sub-chain not accessed
within the last `N x key_cache_age_threshold / 100' hits is to be moved
to the beginning of the warm sub-chain. It then becomes the first
candidate for eviction, because blocks for replacement always are taken
from the beginning of the warm sub-chain.

The midpoint insertion strategy allows you to keep more-valued blocks
always in the cache. If you prefer to use the plain LRU strategy, leave
the `key_cache_division_limit' value set to its default of 100.

The midpoint insertion strategy helps to improve performance when
execution of a query that requires an index scan effectively pushes out
of the cache all the index blocks corresponding to valuable high-level
B-tree nodes. To avoid this, you must use a midpoint insertion strategy
with the `key_cache_division_limit' set to much less than 100. Then
valuable frequently hit nodes are preserved in the hot sub-chain during
an index scan operation as well.


File: manual.info,  Node: index-preloading,  Next: key-cache-block-size,  Prev: midpoint-insertion,  Up: myisam-key-cache

7.4.6.4 Index Preloading
........................

If there are enough blocks in a key cache to hold blocks of an entire
index, or at least the blocks corresponding to its non-leaf nodes, it
makes sense to preload the key cache with index blocks before starting
to use it. Preloading allows you to put the table index blocks into a
key cache buffer in the most efficient way: by reading the index blocks
from disk sequentially.

Without preloading, the blocks are still placed into the key cache as
needed by queries. Although the blocks will stay in the cache, because
there are enough buffers for all of them, they are fetched from disk in
random order, and not sequentially.

To preload an index into a cache, use the `LOAD INDEX INTO CACHE'
statement. For example, the following statement preloads nodes (index
blocks) of indexes of the tables `t1' and `t2':

     mysql> LOAD INDEX INTO CACHE t1, t2 IGNORE LEAVES;
     +---------+--------------+----------+----------+
     | Table   | Op           | Msg_type | Msg_text |
     +---------+--------------+----------+----------+
     | test.t1 | preload_keys | status   | OK       |
     | test.t2 | preload_keys | status   | OK       |
     +---------+--------------+----------+----------+

The `IGNORE LEAVES' modifier causes only blocks for the non-leaf nodes
of the index to be preloaded.  Thus, the statement shown preloads all
index blocks from `t1', but only blocks for the non-leaf nodes from
`t2'.

If an index has been assigned to a key cache using a `CACHE INDEX'
statement, preloading places index blocks into that cache. Otherwise,
the index is loaded into the default key cache.


File: manual.info,  Node: key-cache-block-size,  Next: key-cache-restructuring,  Prev: index-preloading,  Up: myisam-key-cache

7.4.6.5 Key Cache Block Size
............................

It is possible to specify the size of the block buffers for an
individual key cache using the `key_cache_block_size' variable. This
permits tuning of the performance of I/O operations for index files.

The best performance for I/O operations is achieved when the size of
read buffers is equal to the size of the native operating system I/O
buffers. But setting the size of key nodes equal to the size of the I/O
buffer does not always ensure the best overall performance. When
reading the big leaf nodes, the server pulls in a lot of unnecessary
data, effectively preventing reading other leaf nodes.

Currently, you cannot control the size of the index blocks in a table.
This size is set by the server when the `.MYI' index file is created,
depending on the size of the keys in the indexes present in the table
definition. In most cases, it is set equal to the I/O buffer size.


File: manual.info,  Node: key-cache-restructuring,  Prev: key-cache-block-size,  Up: myisam-key-cache

7.4.6.6 Restructuring a Key Cache
.................................

A key cache can be restructured at any time by updating its parameter
values. For example:

     mysql> SET GLOBAL cold_cache.key_buffer_size=4*1024*1024;

If you assign to either the `key_buffer_size' or `key_cache_block_size'
key cache component a value that differs from the component's current
value, the server destroys the cache's old structure and creates a new
one based on the new values. If the cache contains any dirty blocks,
the server saves them to disk before destroying and re-creating the
cache. Restructuring does not occur if you change other key cache
parameters.

When restructuring a key cache, the server first flushes the contents
of any dirty buffers to disk. After that, the cache contents become
unavailable. However, restructuring does not block queries that need to
use indexes assigned to the cache.  Instead, the server directly
accesses the table indexes using native filesystem caching. Filesystem
caching is not as efficient as using a key cache, so although queries
execute, a slowdown can be anticipated. After the cache has been
restructured, it becomes available again for caching indexes assigned
to it, and the use of filesystem caching for the indexes ceases.


File: manual.info,  Node: myisam-index-statistics,  Next: table-cache,  Prev: myisam-key-cache,  Up: optimizing-database-structure

7.4.7 `MyISAM' Index Statistics Collection
------------------------------------------

Storage engines collect statistics about tables for use by the
optimizer. Table statistics are based on value groups, where a value
group is a set of rows with the same key prefix value. For optimizer
purposes, an important statistic is the average value group size.

MySQL uses the average value group size in the following ways:

   * To estimate how may rows must be read for each `ref' access

   * To estimate how many row a partial join will produce; that is, the
     number of rows that an operation of this form will produce:

          (...) JOIN TBL_NAME ON TBL_NAME.KEY = EXPR

As the average value group size for an index increases, the index is
less useful for those two purposes because the average number of rows
per lookup increases: For the index to be good for optimization
purposes, it is best that each index value target a small number of
rows in the table. When a given index value yields a large number of
rows, the index is less useful and MySQL is less likely to use it.

The average value group size is related to table cardinality, which is
the number of value groups. The `SHOW INDEX' statement displays a
cardinality value based on N/S, where N is the number of rows in the
table and S is the average value group size. That ratio yields an
approximate number of value groups in the table.

For a join based on the `<=>' comparison operator, `NULL' is not
treated differently from any other value: `NULL <=> NULL', just as `N
<=> N' for any other N.

However, for a join based on the `=' operator, `NULL' is different from
non-`NULL' values: `EXPR1 = EXPR2' is not true when EXPR1 or EXPR2 (or
both) are `NULL'. This affects `ref' accesses for comparisons of the
form `TBL_NAME.KEY = EXPR': MySQL will not access the table if the
current value of EXPR is `NULL', because the comparison cannot be true.

For `=' comparisons, it does not matter how many `NULL' values are in
the table. For optimization purposes, the relevant value is the average
size of the non-`NULL' value groups. However, MySQL does not currently
allow that average size to be collected or used.

For `MyISAM' tables, you have some control over collection of table
statistics by means of the `myisam_stats_method' system variable. This
variable has two possible values, which differ as follows:

   * When `myisam_stats_method' is `nulls_equal', all `NULL' values are
     treated as identical (that is, they all form a single value group).

     If the `NULL' value group size is much higher than the average
     non-`NULL' value group size, this method skews the average value
     group size upward. This makes index appear to the optimizer to be
     less useful than it really is for joins that look for non-`NULL'
     values. Consequently, the `nulls_equal' method may cause the
     optimizer not to use the index for `ref' accesses when it should.

   * When `myisam_stats_method' is `nulls_unequal', `NULL' values are
     not considered the same. Instead, each `NULL' value forms a
     separate value group of size 1.

     If you have many `NULL' values, this method skews the average
     value group size downward. If the average non-`NULL' value group
     size is large, counting `NULL' values each as a group of size 1
     causes the optimizer to overestimate the value of the index for
     joins that look for non-`NULL' values. Consequently, the
     `nulls_unequal' method may cause the optimizer to use this index
     for `ref' lookups when other methods may be better.

If you tend to use many joins that use `<=>' rather than `=', `NULL'
values are not special in comparisons and one `NULL' is equal to
another. In this case, `nulls_equal' is the appropriate statistics
method.

The `myisam_stats_method' system variable has global and session
values. Setting the global value affects `MyISAM' statistics collection
for all `MyISAM' tables. Setting the session value affects statistics
collection only for the current client connection. This means that you
can force a table's statistics to be regenerated with a given method
without affecting other clients by setting the session value of
`myisam_stats_method'.

To regenerate table statistics, you can use any of the following
methods:

   * Execute `myisamchk --stats_method=METHOD_NAME --analyze'

   * Change the table to cause its statistics to go out of date (for
     example, insert a row and then delete it), and then set
     `myisam_stats_method' and issue an `ANALYZE TABLE' statement

Some caveats regarding the use of `myisam_stats_method':

   * You can force table statistics to be collected explicitly, as just
     described. However, MySQL may also collect statistics
     automatically. For example, if during the course of executing
     statements for a table, some of those statements modify the table,
     MySQL may collect statistics.  (This may occur for bulk inserts or
     deletes, or some `ALTER TABLE' statements, for example.) If this
     happens, the statistics are collected using whatever value
     `myisam_stats_method' has at the time. Thus, if you collect
     statistics using one method, but `myisam_stats_method' is set to
     the other method when a table's statistics are collected
     automatically later, the other method will be used.

   * There is no way to tell which method was used to generate
     statistics for a given `MyISAM' table.

   * `myisam_stats_method' applies only to `MyISAM' tables. Other
     storage engines have only one method for collecting table
     statistics. Usually it is closer to the `nulls_equal' method.


File: manual.info,  Node: table-cache,  Next: creating-many-tables,  Prev: myisam-index-statistics,  Up: optimizing-database-structure

7.4.8 How MySQL Opens and Closes Tables
---------------------------------------

When you execute a `mysqladmin status' command, you should see
something like this:

     Uptime: 426 Running threads: 1 Questions: 11082
     Reloads: 1 Open tables: 12

The `Open tables' value of 12 can be somewhat puzzling if you have only
six tables.

MySQL is multi-threaded, so there may be many clients issuing queries
for a given table simultaneously. To minimize the problem with multiple
client threads having different states on the same table, the table is
opened independently by each concurrent thread. This uses additional
memory but normally increases performance. With `MyISAM' tables, one
extra file descriptor is required for the data file for each client
that has the table open. (By contrast, the index file descriptor is
shared between all threads.)

*Note*:

`table_open_cache' was previously known as `table_cache' in MySQL 5.1.2
and earlier.

The `table_open_cache', `max_connections', and `max_tmp_tables' system
variables affect the maximum number of files the server keeps open. If
you increase one or more of these values, you may run up against a limit
imposed by your operating system on the per-process number of open file
descriptors. Many operating systems allow you to increase the
open-files limit, although the method varies widely from system to
system. Consult your operating system documentation to determine
whether it is possible to increase the limit and how to do so.

`table_open_cache' is related to `max_connections'. For example, for 200
concurrent running connections, you should have a table cache size of
at least `200 x N', where N is the maximum number of tables per join in
any of the queries which you execute. You must also reserve some extra
file descriptors for temporary tables and files.

Make sure that your operating system can handle the number of open file
descriptors implied by the `table_open_cache' setting. If
`table_open_cache' is set too high, MySQL may run out of file
descriptors and refuse connections, fail to perform queries, and be
very unreliable. You also have to take into account that the `MyISAM'
storage engine needs two file descriptors for each unique open table.
You can increase the number of file descriptors available to MySQL using
the `--open-files-limit' startup option to `mysqld'. See *Note
not-enough-file-handles::.

The cache of open tables is kept at a level of `table_open_cache'
entries. The default value is 64; this can be changed with the
`--table_open_cache' option to `mysqld'. Note that MySQL may
temporarily open more tables than this to execute queries.

MySQL Enterprise

Performance may suffer if `table_open_cache' is set too low. For expert
advice on the optimum value for this variable, subscribe to the MySQL
Enterprise Monitor. For more information see
`http://www.mysql.com/products/enterprise/advisors.html'.

MySQL closes an unused table and removes it from the table cache under
the following circumstances:

   * When the cache is full and a thread tries to open a table that is
     not in the cache.

   * When the cache contains more than `table_open_cache' entries and a
     table in the cache is no longer being used by any threads.

   * When a table flushing operation occurs. This happens when someone
     issues a `FLUSH TABLES' statement or executes a `mysqladmin
     flush-tables' or `mysqladmin refresh' command.

When the table cache fills up, the server uses the following procedure
to locate a cache entry to use:

   * Tables that are not currently in use are released, beginning with
     the table least recently used.

   * If a new table needs to be opened, but the cache is full and no
     tables can be released, the cache is temporarily extended as
     necessary. When the cache is in a temporarily extended state and a
     table goes from a used to unused state, the table is closed and
     released from the cache.

A `MyISAM' table is opened for each concurrent access. This means the
table needs to be opened twice if two threads access the same table or
if a thread accesses the table twice in the same query (for example, by
joining the table to itself). Each concurrent open requires an entry in
the table cache. The first open of any `MyISAM' table takes two file
descriptors: one for the data file and one for the index file. Each
additional use of the table takes only one file descriptor for the data
file. The index file descriptor is shared among all threads.

If you are opening a table with the `HANDLER TBL_NAME OPEN' statement, a
dedicated table object is allocated for the thread. This table object
is not shared by other threads and is not closed until the thread calls
`HANDLER TBL_NAME CLOSE' or the thread terminates. When this happens,
the table is put back in the table cache (if the cache is not full). See
*Note handler::.

You can determine whether your table cache is too small by checking the
`mysqld' status variable `Opened_tables', which indicates the number of
table-opening operations since the server started:

     mysql> SHOW GLOBAL STATUS LIKE 'Opened_tables';
     +---------------+-------+
     | Variable_name | Value |
     +---------------+-------+
     | Opened_tables | 2741  |
     +---------------+-------+

If the value is very large or increases rapidly, even when you have not
issued many `FLUSH TABLES' statements, you should increase the table
cache size. See *Note server-system-variables::, and *Note
server-status-variables::.


File: manual.info,  Node: creating-many-tables,  Prev: table-cache,  Up: optimizing-database-structure

7.4.9 Drawbacks to Creating Many Tables in the Same Database
------------------------------------------------------------

If you have many `MyISAM' tables in the same database directory, open,
close, and create operations are slow.  If you execute `SELECT'
statements on many different tables, there is a little overhead when
the table cache is full, because for every table that has to be opened,
another must be closed. You can reduce this overhead by increasing the
number of entries allowed in the table cache.


File: manual.info,  Node: optimizing-the-server,  Next: disk-issues,  Prev: optimizing-database-structure,  Up: optimization

7.5 Optimizing the MySQL Server
===============================

* Menu:

* system-optimization::          System Factors and Startup Parameter Tuning
* server-parameters::            Tuning Server Parameters
* controlling-optimizer::        Controlling Query Optimizer Performance
* query-cache::                  The MySQL Query Cache
* thread-information::           Examining Thread Information
* compile-and-link-options::     How Compiling and Linking Affects the Speed of MySQL
* connection-threads::           How MySQL Uses Threads for Client Connections
* memory-use::                   How MySQL Uses Memory
* internal-temporary-tables::    How MySQL Uses Internal Temporary Tables
* dns::                          How MySQL Uses DNS


File: manual.info,  Node: system-optimization,  Next: server-parameters,  Prev: optimizing-the-server,  Up: optimizing-the-server

7.5.1 System Factors and Startup Parameter Tuning
-------------------------------------------------

We start with system-level factors, because some of these decisions
must be made very early to achieve large performance gains. In other
cases, a quick look at this section may suffice.  However, it is always
nice to have a sense of how much can be gained by changing factors that
apply at this level.

The operating system to use is very important. To get the best use of
multiple-CPU machines, you should use Solaris (because its threads
implementation works well) or Linux (because the 2.4 and later kernels
have good SMP support). Note that older Linux kernels have a 2GB
filesize limit by default. If you have such a kernel and a need for
files larger than 2GB, you should get the Large File Support (LFS)
patch for the ext2 filesystem. Other filesystems such as ReiserFS and
XFS do not have this 2GB limitation.

Before using MySQL in production, we advise you to test it on your
intended platform.

Other tips:

   * If you have enough RAM, you could remove all swap devices.  Some
     operating systems use a swap device in some contexts even if you
     have free memory.

   * Avoid external locking. Since MySQL 4.0, the default has been for
     external locking to be disabled on all systems. The
     `--external-locking' and `--skip-external-locking' options
     explicitly enable and disable external locking.

     Note that disabling external locking does not affect MySQL's
     functionality as long as you run only one server. Just remember to
     take down the server (or lock and flush the relevant tables)
     before you run `myisamchk'. On some systems it is mandatory to
     disable external locking because it does not work, anyway.

     The only case in which you cannot disable external locking is when
     you run multiple MySQL _servers_ (not clients) on the same data,
     or if you run `myisamchk' to check (not repair) a table without
     telling the server to flush and lock the tables first. Note that
     using multiple MySQL servers to access the same data concurrently
     is generally _not_ recommended, except when using MySQL Cluster.

     The `LOCK TABLES' and `UNLOCK TABLES' statements use internal
     locking, so you can use them even if external locking is disabled.


File: manual.info,  Node: server-parameters,  Next: controlling-optimizer,  Prev: system-optimization,  Up: optimizing-the-server

7.5.2 Tuning Server Parameters
------------------------------

You can determine the default buffer sizes used by the `mysqld' server
using this command:

     shell> mysqld --verbose --help

This command produces a list of all `mysqld' options and configurable
system variables. The output includes the default variable values and
looks something like this:

     help                              TRUE
     abort-slave-event-count           0
     allow-suspicious-udfs             FALSE
     auto-increment-increment          1
     auto-increment-offset             1
     automatic-sp-privileges           TRUE
     basedir                           /home/mysql/
     bind-address                      (No default value)
     character-set-client-handshake    TRUE
     character-set-server              latin1
     character-sets-dir                /home/mysql/share/mysql/charsets/
     chroot                            (No default value)
     collation-server                  latin1_swedish_ci
     completion-type                   0
     concurrent-insert                 1
     console                           FALSE
     datadir                           /home/mysql/var/
     default-character-set             latin1
     default-collation                 latin1_swedish_ci
     default-time-zone                 (No default value)
     disconnect-slave-event-count      0
     enable-locking                    FALSE
     enable-pstack                     FALSE
     engine-condition-pushdown         TRUE
     external-locking                  FALSE
     gdb                               FALSE
     large-pages                       FALSE
     init-connect                      (No default value)
     init-file                         (No default value)
     init-slave                        (No default value)
     innodb                            TRUE
     innodb_checksums                  TRUE
     innodb_data_home_dir              (No default value)
     innodb_doublewrite                TRUE
     innodb_fast_shutdown              1
     innodb_file_per_table             FALSE
     innodb_flush_log_at_trx_commit    1
     innodb_flush_method               (No default value)
     innodb_locks_unsafe_for_binlog    FALSE
     innodb_log_group_home_dir         (No default value)
     innodb_max_dirty_pages_pct        90
     innodb_max_purge_lag              0
     innodb_status_file                FALSE
     innodb_table_locks                TRUE
     innodb_support_xa                 TRUE
     isam                              FALSE
     language                          /home/mysql/share/mysql/english
     local-infile                      TRUE
     log                               /home/mysql/var/master1.log
     log-bin                           /home/mysql/var/master1
     log-bin-index                     (No default value)
     log-bin-trust-routine-creators    FALSE
     log-error                         /home/mysql/var/master1.err
     log-isam                          myisam.log
     log-queries-not-using-indexes     FALSE
     log-short-format                  FALSE
     log-slave-updates                 FALSE
     log-slow-admin-statements         FALSE
     log-slow-queries                  (No default value)
     log-tc                            tc.log
     log-tc-size                       24576
     log-update                        (No default value)
     log-warnings                      1
     low-priority-updates              FALSE
     master-connect-retry              60
     master-host                       (No default value)
     master-info-file                  master.info
     master-password                   (No default value)
     master-port                       3306
     master-retry-count                86400
     master-ssl                        FALSE
     master-ssl-ca                     (No default value)
     master-ssl-capath                 (No default value)
     master-ssl-cert                   (No default value)
     master-ssl-cipher                 (No default value)
     master-ssl-key                    (No default value)
     master-user                       test
     max-binlog-dump-events            0
     memlock                           FALSE
     myisam-recover                    OFF
     ndbcluster                        FALSE
     ndb-connectstring                 (No default value)
     ndb-mgmd-host                     (No default value)
     ndb-nodeid                        0
     ndb-autoincrement-prefetch-sz     32
     ndb-distibution                   KEYHASH
     ndb-force-send                    TRUE
     ndb_force_send                    TRUE
     ndb-use-exact-count               TRUE
     ndb_use_exact_count               TRUE
     ndb-shm                           FALSE
     ndb-optimized-node-selection      TRUE
     ndb-cache-check-time              0
     ndb-index-stat-enable             TRUE
     ndb-index-stat-cache-entries      32
     ndb-index-stat-update-freq        20
     new                               FALSE
     old-alter-table                   FALSE
     old-passwords                     FALSE
     old-style-user-limits             FALSE
     pid-file                          /home/mysql/var/hostname.pid1
     port                              3306
     relay-log                         (No default value)
     relay-log-index                   (No default value)
     relay-log-info-file               relay-log.info
     replicate-same-server-id          FALSE
     report-host                       (No default value)
     report-password                   (No default value)
     report-port                       3306
     report-user                       (No default value)
     rpl-recovery-rank                 0
     safe-user-create                  FALSE
     secure-auth                       FALSE
     server-id                         1
     show-slave-auth-info              FALSE
     skip-grant-tables                 FALSE
     skip-slave-start                  FALSE
     slave-load-tmpdir                 /tmp/
     socket                            /tmp/mysql.sock
     sporadic-binlog-dump-fail         FALSE
     sql-mode                          OFF
     symbolic-links                    TRUE
     tc-heuristic-recover              (No default value)
     temp-pool                         TRUE
     timed_mutexes                     FALSE
     tmpdir                            (No default value)
     use-symbolic-links                TRUE
     verbose                           TRUE
     warnings                          1
     back_log                          50
     binlog_cache_size                 32768
     bulk_insert_buffer_size           8388608
     connect_timeout                   5
     date_format                       (No default value)
     datetime_format                   (No default value)
     default_week_format               0
     delayed_insert_limit              100
     delayed_insert_timeout            300
     delayed_queue_size                1000
     expire_logs_days                  0
     flush_time                        0
     ft_max_word_len                   84
     ft_min_word_len                   4
     ft_query_expansion_limit          20
     ft_stopword_file                  (No default value)
     group_concat_max_len              1024
     innodb_additional_mem_pool_size   1048576
     innodb_autoextend_increment       8
     innodb_buffer_pool_size           8388608
     innodb_concurrency_tickets        500
     innodb_file_io_threads            4
     innodb_force_recovery             0
     innodb_lock_wait_timeout          50
     innodb_log_buffer_size            1048576
     innodb_log_file_size              5242880
     innodb_log_files_in_group         2
     innodb_mirrored_log_groups        1
     innodb_open_files                 300
     innodb_sync_spin_loops            20
     innodb_thread_concurrency         20
     innodb_commit_concurrency         0
     innodb_thread_sleep_delay         10000
     interactive_timeout               28800
     join_buffer_size                  131072
     key_buffer_size                   8388600
     key_cache_age_threshold           300
     key_cache_block_size              1024
     key_cache_division_limit          100
     long_query_time                   10
     lower_case_table_names            0
     max_allowed_packet                1048576
     max_binlog_cache_size             4294967295
     max_binlog_size                   1073741824
     max_connect_errors                10
     max_connections                   100
     max_delayed_threads               20
     max_error_count                   64
     max_heap_table_size               16777216
     max_join_size                     4294967295
     max_length_for_sort_data          1024
     max_relay_log_size                0
     max_seeks_for_key                 4294967295
     max_sort_length                   1024
     max_tmp_tables                    32
     max_user_connections              0
     max_write_lock_count              4294967295
     multi_range_count                 256
     myisam_block_size                 1024
     myisam_data_pointer_size          6
     myisam_max_sort_file_size         2147483647
     myisam_repair_threads             1
     myisam_sort_buffer_size           8388608
     myisam_stats_method               nulls_unequal
     net_buffer_length                 16384
     net_read_timeout                  30
     net_retry_count                   10
     net_write_timeout                 60
     open_files_limit                  0
     optimizer_prune_level             1
     optimizer_search_depth            62
     preload_buffer_size               32768
     query_alloc_block_size            8192
     query_cache_limit                 1048576
     query_cache_min_res_unit          4096
     query_cache_size                  0
     query_cache_type                  1
     query_cache_wlock_invalidate      FALSE
     query_prealloc_size               8192
     range_alloc_block_size            2048
     read_buffer_size                  131072
     read_only                         FALSE
     read_rnd_buffer_size              262144
     div_precision_increment           4
     record_buffer                     131072
     relay_log_purge                   TRUE
     relay_log_space_limit             0
     slave_compressed_protocol         FALSE
     slave_net_timeout                 3600
     slave_transaction_retries         10
     slow_launch_time                  2
     sort_buffer_size                  2097144
     sync-binlog                       0
     sync-frm                          TRUE
     sync-replication                  0
     sync-replication-slave-id         0
     sync-replication-timeout          10
     table_open_cache                  64
     table_lock_wait_timeout           50
     thread_cache_size                 0
     thread_concurrency                10
     thread_stack                      196608
     time_format                       (No default value)
     tmp_table_size                    33554432
     transaction_alloc_block_size      8192
     transaction_prealloc_size         4096
     updatable_views_with_limit        1
     wait_timeout                      28800

For a `mysqld' server that is currently running, you can see the
current values of its system variables by connecting to it and issuing
this statement:

     mysql> SHOW VARIABLES;

You can also see some statistical and status indicators for a running
server by issuing this statement:

     mysql> SHOW STATUS;

System variable and status information also can be obtained using
`mysqladmin':

     shell> mysqladmin variables
     shell> mysqladmin extended-status

For a full description of all system and status variables, see *Note
server-system-variables::, and *Note server-status-variables::.

MySQL uses algorithms that are very scalable, so you can usually run
with very little memory. However, normally you get better performance
by giving MySQL more memory.

When tuning a MySQL server, the two most important variables to
configure are `key_buffer_size' and `table_open_cache'. You should
first feel confident that you have these set appropriately before
trying to change any other variables.

The following examples indicate some typical variable values for
different runtime configurations.

   * If you have at least 256MB of memory and many tables and want
     maximum performance with a moderate number of clients, you should
     use something like this:

          shell> mysqld_safe --key_buffer_size=64M --table_open_cache=256 \
                     --sort_buffer_size=4M --read_buffer_size=1M &

   * If you have only 128MB of memory and only a few tables, but you
     still do a lot of sorting, you can use something like this:

          shell> mysqld_safe --key_buffer_size=16M --sort_buffer_size=1M

     If there are very many simultaneous connections, swapping problems
     may occur unless `mysqld' has been configured to use very little
     memory for each connection.  `mysqld' performs better if you have
     enough memory for all connections.

   * With little memory and lots of connections, use something like
     this:

          shell> mysqld_safe --key_buffer_size=512K --sort_buffer_size=100K \
                     --read_buffer_size=100K &

     Or even this:

          shell> mysqld_safe --key_buffer_size=512K --sort_buffer_size=16K \
                     --table_open_cache=32 --read_buffer_size=8K \
                     --net_buffer_length=1K &

If you are performing `GROUP BY' or `ORDER BY' operations on tables
that are much larger than your available memory, you should increase
the value of `read_rnd_buffer_size' to speed up the reading of rows
following sorting operations.

You can make use of the example option files included with your MySQL
distribution; see *Note option-files-preconfigured::.

If you specify an option on the command line for `mysqld' or
`mysqld_safe', it remains in effect only for that invocation of the
server. To use the option every time the server runs, put it in an
option file.

To see the effects of a parameter change, do something like this:

     shell> mysqld --key_buffer_size=32M --verbose --help

The variable values are listed near the end of the output. Make sure
that the `--verbose' and `--help' options are last. Otherwise, the
effect of any options listed after them on the command line are not
reflected in the output.

For information on tuning the `InnoDB' storage engine, see *Note
innodb-tuning::.

MySQL Enterprise

For expert advice on tuning system parameters subscribe to the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: controlling-optimizer,  Next: query-cache,  Prev: server-parameters,  Up: optimizing-the-server

7.5.3 Controlling Query Optimizer Performance
---------------------------------------------

The task of the query optimizer is to find an optimal plan for
executing an SQL query. Because the difference in performance between
`good' and `bad' plans can be orders of magnitude (that is, seconds
versus hours or even days), most query optimizers, including that of
MySQL, perform a more or less exhaustive search for an optimal plan
among all possible query evaluation plans. For join queries, the number
of possible plans investigated by the MySQL optimizer grows
exponentially with the number of tables referenced in a query.  For
small numbers of tables (typically less than 7-10) this is not a
problem. However, when larger queries are submitted, the time spent in
query optimization may easily become the major bottleneck in the
server's performance.

A more flexible method for query optimization allows the user to
control how exhaustive the optimizer is in its search for an optimal
query evaluation plan. The general idea is that the fewer plans that
are investigated by the optimizer, the less time it spends in compiling
a query. On the other hand, because the optimizer skips some plans, it
may miss finding an optimal plan.

The behavior of the optimizer with respect to the number of plans it
evaluates can be controlled via two system variables:

   * The `optimizer_prune_level' variable tells the optimizer to skip
     certain plans based on estimates of the number of rows accessed
     for each table. Our experience shows that this kind of `educated
     guess' rarely misses optimal plans, and may dramatically reduce
     query compilation times. That is why this option is on
     (`optimizer_prune_level=1') by default.  However, if you believe
     that the optimizer missed a better query plan, this option can be
     switched off (`optimizer_prune_level=0') with the risk that query
     compilation may take much longer. Note that, even with the use of
     this heuristic, the optimizer still explores a roughly exponential
     number of plans.

   * The `optimizer_search_depth' variable tells how far into the
     `future' of each incomplete plan the optimizer should look to
     evaluate whether it should be expanded further. Smaller values of
     `optimizer_search_depth' may result in orders of magnitude smaller
     query compilation times. For example, queries with 12, 13, or more
     tables may easily require hours and even days to compile if
     `optimizer_search_depth' is close to the number of tables in the
     query. At the same time, if compiled with `optimizer_search_depth'
     equal to 3 or 4, the optimizer may compile in less than a minute
     for the same query. If you are unsure of what a reasonable value is
     for `optimizer_search_depth', this variable can be set to 0 to
     tell the optimizer to determine the value automatically.


File: manual.info,  Node: query-cache,  Next: thread-information,  Prev: controlling-optimizer,  Up: optimizing-the-server

7.5.4 The MySQL Query Cache
---------------------------

* Menu:

* query-cache-how::              How the Query Cache Operates
* query-cache-in-select::        Query Cache `SELECT' Options
* query-cache-configuration::    Query Cache Configuration
* query-cache-status-and-maintenance::  Query Cache Status and Maintenance

The query cache stores the text of a `SELECT' statement together with
the corresponding result that was sent to the client. If an identical
statement is received later, the server retrieves the results from the
query cache rather than parsing and executing the statement again.

The query cache is extremely useful in an environment where you have
tables that do not change very often and for which the server receives
many identical queries. This is a typical situation for many Web
servers that generate many dynamic pages based on database content.

*Note*:

The query cache does not return stale data. When tables are modified,
any relevant entries in the query cache are flushed.

The query cache does not work in an environment where you have multiple
`mysqld' servers updating the same `MyISAM' tables.

*Note*:

The query cache is not used for server-side prepared statements before
MySQL 5.1.17. If you are using server-side prepared statements,
consider that these statements will not be satisfied by the query
cache. As of 5.1.17, the query cache is used under the conditions
described in *Note query-cache-how::.

Some performance data for the query cache follows. These results were
generated by running the MySQL benchmark suite on a Linux Alpha
2x500MHz system with 2GB RAM and a 64MB query cache.

   * If all the queries you are performing are simple (such as
     selecting a row from a table with one row), but still differ so
     that the queries cannot be cached, the overhead for having the
     query cache active is 13%. This could be regarded as the worst
     case scenario. In real life, queries tend to be much more
     complicated, so the overhead normally is significantly lower.

   * Searches for a single row in a single-row table are 238% faster
     with the query cache than without it. This can be regarded as
     close to the minimum speedup to be expected for a query that is
     cached.

To disable the query cache at server startup, set the
`query_cache_size' system variable to 0. By disabling the query cache
code, there is no noticeable overhead.  If you build MySQL from source,
query cache capabilities can be excluded from the server entirely by
invoking `configure' with the `--without-query-cache' option.


File: manual.info,  Node: query-cache-how,  Next: query-cache-in-select,  Prev: query-cache,  Up: query-cache

7.5.4.1 How the Query Cache Operates
....................................

This section describes how the query cache works when it is
operational. *Note query-cache-configuration::, describes how to
control whether it is operational.

Incoming queries are compared to those in the query cache before
parsing, so the following two queries are regarded as different by the
query cache:

     SELECT * FROM TBL_NAME
     Select * from TBL_NAME

Queries must be _exactly_ the same (byte for byte) to be seen as
identical. In addition, query strings that are identical may be treated
as different for other reasons. Queries that use different databases,
different protocol versions, or different default character sets are
considered different queries and are cached separately.

The cache is not used for queries of the following types:

   * Queries that are a subquery of an outer query

   * Queries executed within the body of a stored function, trigger, or
     event

Before a query result is fetched from the query cache, MySQL checks
that the user has `SELECT' privilege for all databases and tables
involved. If this is not the case, the cached result is not used.

If a query result is returned from query cache, the server increments
the `Qcache_hits' status variable, not `Com_select'. See *Note
query-cache-status-and-maintenance::.

If a table changes, all cached queries that use the table become
invalid and are removed from the cache. This includes queries that use
`MERGE' tables that map to the changed table. A table can be changed by
many types of statements, such as `INSERT', `UPDATE', `DELETE',
`TRUNCATE', `ALTER TABLE', `DROP TABLE', or `DROP DATABASE'.

The query cache also works within transactions when using `InnoDB'
tables.

In MySQL 5.1, the results of a `SELECT' query on a view is cached.

The query cache works for `SELECT SQL_CALC_FOUND_ROWS ...' queries and
stores a value that is returned by a following `SELECT FOUND_ROWS()'
query.  `FOUND_ROWS()' returns the correct value even if the preceding
query was fetched from the cache because the number of found rows is
also stored in the cache. The `SELECT FOUND_ROWS()' query itself cannot
be cached.

Before MySQL 5.1.17, prepared statements do not use the query cache.
Beginning with 5.1.17, prepared statements use the query cache under
certain conditions, which differ depending on the preparation method:

   * Statements that are issued via the binary protocol using *Note
     `mysql_stmt_prepare()': mysql-stmt-prepare. and *Note
     `mysql_stmt_execute()': mysql-stmt-execute. See *Note
     c-api-prepared-statements::.

     For a prepared statement executed via the binary protocol,
     comparison with statements in the query cache is based on the text
     of the statement after expansion of `?' parameter markers. The
     statement is compared only with other cached statements that were
     executed via the binary protocol. That is, for query cache
     purposes, statements issued via the binary protocol are distinct
     from statements issued via the text protocol.

   * Statements that are issued via the text (non-binary) protocol
     using `PREPARE' and `EXECUTE'. See *Note
     sql-syntax-prepared-statements::. These are denoted SQL PS
     statements here.

     Before MySQL 5.1.21, for a prepared statement executed via
     `PREPARE' and `EXECUTE', it is not cached if it contains any `?'
     parameter markers. In that case, the statement after parameter
     expansion contains references to user variables, which prevents
     caching, even for non-prepared statements.  If the statement
     contains no parameter markers, the statement is compared with
     statements in the query cache that were executed via the text
     protocol (that is, it is compared with other SQL PS statements and
     non-prepared statements). As of MySQL 5.1.21, this limitation is
     lifted and prepared statments that contain parameter markers can
     be cached because expansion directly substitutes the user variable
     values.

A query cannot be cached if it contains any of the functions shown in
the following table:

`BENCHMARK()'            `CONNECTION_ID()'        `CONVERT_TZ()'
`CURDATE()'              `CURRENT_DATE()'         `CURRENT_TIME()'
`CURRENT_TIMESTAMP()'    `CURTIME()'              `DATABASE()'
`ENCRYPT()' with one     `FOUND_ROWS()'           `GET_LOCK()'
parameter                                         
`LAST_INSERT_ID()'       `LOAD_FILE()'            `MASTER_POS_WAIT()'
`NOW()'                  `RAND()'                 `RELEASE_LOCK()'
`SLEEP()'                `SYSDATE()'              `UNIX_TIMESTAMP()' with
                                                  no parameters
`USER()'                 `UUID()'                 `UUID_SHORT()'

A query also is not cached under these conditions:

   * It refers to user-defined functions (UDFs) or stored functions.

   * It refers to user variables or local stored routine variables.

   * It refers to tables in the `mysql' or `INFORMATION_SCHEMA' system
     database.

   * It is of any of the following forms:

          SELECT ... IN SHARE MODE
          SELECT ... FOR UPDATE
          SELECT ... INTO OUTFILE ...
          SELECT ... INTO DUMPFILE ...
          SELECT * FROM ... WHERE autoincrement_col IS NULL

     The last form is not cached because it is used as the ODBC
     workaround for obtaining the last insert ID value. See the MyODBC
     section of *Note connectors::.

   * It uses `TEMPORARY' tables.

   * It does not use any tables.

   * It generates warnings.

   * The user has a column-level privilege for any of the involved
     tables.


File: manual.info,  Node: query-cache-in-select,  Next: query-cache-configuration,  Prev: query-cache-how,  Up: query-cache

7.5.4.2 Query Cache `SELECT' Options
....................................

Two query cache-related options may be specified in `SELECT' statements:

   * `SQL_CACHE'

     The query result is cached if it is cacheable and the value of the
     `query_cache_type' system variable is `ON' or `DEMAND'.

   * `SQL_NO_CACHE'

     The query result is not cached.

Examples:

     SELECT SQL_CACHE id, name FROM customer;
     SELECT SQL_NO_CACHE id, name FROM customer;


File: manual.info,  Node: query-cache-configuration,  Next: query-cache-status-and-maintenance,  Prev: query-cache-in-select,  Up: query-cache

7.5.4.3 Query Cache Configuration
.................................

The `have_query_cache' server system variable indicates whether the
query cache is available:

     mysql> SHOW VARIABLES LIKE 'have_query_cache';
     +------------------+-------+
     | Variable_name    | Value |
     +------------------+-------+
     | have_query_cache | YES   |
     +------------------+-------+

When using a standard MySQL binary, this value is always `YES', even if
query caching is disabled.

Several other system variables control query cache operation.  These
can be set in an option file or on the command line when starting
`mysqld'. The query cache system variables all have names that begin
with `query_cache_'. They are described briefly in *Note
server-system-variables::, with additional configuration information
given here.

To set the size of the query cache, set the `query_cache_size' system
variable. Setting it to 0 disables the query cache. The default size is
0, so the query cache is disabled by default.

MySQL Enterprise

For expert advice on configuring the query cache subscribe to the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

*Note*:

When using the Windows Configuration Wizard to install or configure
MySQL, the default value for `query_cache_size' will be configured
automatically for you based on the different configuration types
available. When using the Windows Configuration Wizard, the query cache
may be enabled (i.e. set to a non-zero value) due to the selected
configuration. The query cache is also controlled by the setting of the
`query_cache_type' variable. You should check the values of these
variables as set in your `my.ini' file after configuration has taken
place.

When you set `query_cache_size' to a non-zero value, keep in mind that
the query cache needs a minimum size of about 40KB to allocate its
structures. (The exact size depends on system architecture.) If you set
the value too small, you'll get a warning, as in this example:

     mysql> SET GLOBAL query_cache_size = 40000;
     Query OK, 0 rows affected, 1 warning (0.00 sec)

     mysql> SHOW WARNINGS\G
     *************************** 1. row ***************************
       Level: Warning
        Code: 1282
     Message: Query cache failed to set size 39936; »
              new query cache size is 0

     mysql> SET GLOBAL query_cache_size = 41984;
     Query OK, 0 rows affected (0.00 sec)

     mysql> SHOW VARIABLES LIKE 'query_cache_size';
     +------------------+-------+
     | Variable_name    | Value |
     +------------------+-------+
     | query_cache_size | 41984 |
     +------------------+-------+

For the query cache to actually be able to hold any query results, its
size must be set larger:

     mysql> SET GLOBAL query_cache_size = 1000000;
     Query OK, 0 rows affected (0.04 sec)

     mysql> SHOW VARIABLES LIKE 'query_cache_size';
     +------------------+--------+
     | Variable_name    | Value  |
     +------------------+--------+
     | query_cache_size | 999424 |
     +------------------+--------+
     1 row in set (0.00 sec)

The `query_cache_size' is aligned to the nearest 1024 byte block. The
value reported may therefore be different from the value that you set.

If the query cache size is greater than 0, the `query_cache_type'
variable influences how it works. This variable can be set to the
following values:

   * A value of `0' or `OFF' prevents caching or retrieval of cached
     results.

   * A value of `1' or `ON' allows caching except of those statements
     that begin with `SELECT SQL_NO_CACHE'.

   * A value of `2' or `DEMAND' causes caching of only those statements
     that begin with `SELECT SQL_CACHE'.

Setting the `GLOBAL' `query_cache_type' value determines query cache
behavior for all clients that connect after the change is made.
Individual clients can control cache behavior for their own connection
by setting the `SESSION' `query_cache_type' value. For example, a
client can disable use of the query cache for its own queries like this:

     mysql> SET SESSION query_cache_type = OFF;

To control the maximum size of individual query results that can be
cached, set the `query_cache_limit' system variable. The default value
is 1MB.

*Note*:

You can set the maximum size that can be specified for the query cache
during runtine with the `SET' statement by using the
`--maximum-query_cache_size=32M' option on the command line or in the
configuration file.

When a query is to be cached, its result (the data sent to the client)
is stored in the query cache during result retrieval.  Therefore the
data usually is not handled in one big chunk.  The query cache
allocates blocks for storing this data on demand, so when one block is
filled, a new block is allocated.  Because memory allocation operation
is costly (timewise), the query cache allocates blocks with a minimum
size given by the `query_cache_min_res_unit' system variable.  When a
query is executed, the last result block is trimmed to the actual data
size so that unused memory is freed. Depending on the types of queries
your server executes, you might find it helpful to tune the value of
`query_cache_min_res_unit':

   * The default value of `query_cache_min_res_unit' is 4KB. This
     should be adequate for most cases.

   * If you have a lot of queries with small results, the default block
     size may lead to memory fragmentation, as indicated by a large
     number of free blocks. Fragmentation can force the query cache to
     prune (delete) queries from the cache due to lack of memory. In
     this case, you should decrease the value of
     `query_cache_min_res_unit'. The number of free blocks and queries
     removed due to pruning are given by the values of the
     `Qcache_free_blocks' and `Qcache_lowmem_prunes' status variables.

   * If most of your queries have large results (check the
     `Qcache_total_blocks' and `Qcache_queries_in_cache' status
     variables), you can increase performance by increasing
     `query_cache_min_res_unit'. However, be careful to not make it too
     large (see the previous item).

MySQL Enterprise

If the query cache is under-utilized, performance will suffer. Advice
on avoiding this problem is provided to subscribers to the MySQL
Enterprise Monitor. For more information see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: query-cache-status-and-maintenance,  Prev: query-cache-configuration,  Up: query-cache

7.5.4.4 Query Cache Status and Maintenance
..........................................

You can check whether the query cache is present in your MySQL server
using the following statement:

     mysql> SHOW VARIABLES LIKE 'have_query_cache';
     +------------------+-------+
     | Variable_name    | Value |
     +------------------+-------+
     | have_query_cache | YES   |
     +------------------+-------+

You can defragment the query cache to better utilize its memory with
the `FLUSH QUERY CACHE' statement. The statement does not remove any
queries from the cache.

The `RESET QUERY CACHE' statement removes all query results from the
query cache. The `FLUSH TABLES' statement also does this.

To monitor query cache performance, use `SHOW STATUS' to view the cache
status variables:

     mysql> SHOW STATUS LIKE 'Qcache%';
     +-------------------------+--------+
     | Variable_name           | Value  |
     +-------------------------+--------+
     | Qcache_free_blocks      | 36     |
     | Qcache_free_memory      | 138488 |
     | Qcache_hits             | 79570  |
     | Qcache_inserts          | 27087  |
     | Qcache_lowmem_prunes    | 3114   |
     | Qcache_not_cached       | 22989  |
     | Qcache_queries_in_cache | 415    |
     | Qcache_total_blocks     | 912    |
     +-------------------------+--------+

Descriptions of each of these variables are given in *Note
server-status-variables::. Some uses for them are described here.

The total number of `SELECT' queries is given by this formula:

       Com_select
     + Qcache_hits
     + queries with errors found by parser

The `Com_select' value is given by this formula:

       Qcache_inserts
     + Qcache_not_cached
     + queries with errors found during the column-privileges check

The query cache uses variable-length blocks, so `Qcache_total_blocks'
and `Qcache_free_blocks' may indicate query cache memory fragmentation.
After `FLUSH QUERY CACHE', only a single free block remains.

Every cached query requires a minimum of two blocks (one for the query
text and one or more for the query results). Also, every table that is
used by a query requires one block.  However, if two or more queries
use the same table, only one table block needs to be allocated.

The information provided by the `Qcache_lowmem_prunes' status variable
can help you tune the query cache size. It counts the number of queries
that have been removed from the cache to free up memory for caching new
queries. The query cache uses a least recently used (LRU) strategy to
decide which queries to remove from the cache. Tuning information is
given in *Note query-cache-configuration::.


File: manual.info,  Node: thread-information,  Next: compile-and-link-options,  Prev: query-cache,  Up: optimizing-the-server

7.5.5 Examining Thread Information
----------------------------------

* Menu:

* thread-commands::              Thread Command Values
* general-thread-states::        General Thread States
* delayed-insert-thread-states::  Delayed-Insert Thread States
* master-thread-states::         Replication Master Thread States
* slave-io-thread-states::       Replication Slave I/O Thread States
* slave-sql-thread-states::      Replication Slave SQL Thread States
* slave-connection-thread-states::  Replication Slave Connection Thread States
* mysql-cluster-thread-states::  MySQL Cluster Thread States
* event-scheduler-thread-states::  Event Scheduler Thread States

When you are attempting to ascertain what your MySQL server is doing,
it can be helpful to examine the process list, which is the set of
threads currently executing within the server.  Process list
information is available from these sources:

   * The `SHOW [FULL] PROCESSLIST' statement (*Note show-processlist::)

   * The `INFORMATION_SCHEMA' `PROCESSLIST' table (*Note
     processlist-table::)

   * The `myqladmin processlist' command (*Note mysqladmin::)

You can always view information about your own threads. To view
information about threads being executed for other accounts, you must
have the `PROCESS' privilege.

Each process list entry contains several pieces of information:

   * `Id' is the connection identifier for the client associated with
     the thread.

   * `User' and `Host' indicate the account associated with the thread.

   * `db' is the default database for the thread, or `NULL' if none is
     selected.

   * `Command' and `State' indicate what the thread is doing.

     Most states correspond to very quick operations. If a thread stays
     in a given state for many seconds, there might be a problem that
     needs to be investigated.

   * `Time' indicates how long the thread has been in its current state.

   * `Info' contains the text of the statement being executed by the
     thread, or `NULL' if it is not executing one. By default, this
     value contains only the first 100 characters of the statement. To
     see the complete statements, use `SHOW FULL PROCESSLIST'.

The following sections list the possible `Command' values, and `State'
values grouped by category. The meaning for some of these values is
self-evident. For others, additional description is provided.


File: manual.info,  Node: thread-commands,  Next: general-thread-states,  Prev: thread-information,  Up: thread-information

7.5.5.1 Thread Command Values
.............................

A thread can have any of the following `Command' values:

   * `Binlog Dump'

     This is a thread on a master server for sending binary log
     contents to a slave server.

   * `Change user'

     The thread is executing a change-user operation.

   * `Close stmt'

     The thread is closing a prepared statement.

   * `Connect'

     A replication slave is connected to its master.

   * `Connect Out'

     A replication slave is connecting to its master.

   * `Create DB'

     The thread is executing a create-database operation.

   * `Daemon'

     This thread is internal to the server, not a thread that services
     a client connection.

   * `Debug'

     The thread is generating debugging information.

   * `Delayed insert'

     The thread is a delayed-insert handler.

   * `Drop DB'

     The thread is executing a drop-database operation.

   * `Error'

   * `Execute'

     The thread is executing a prepared statement.

   * `Fetch'

     The thread is fetching the results from executing a prepared
     statement.

   * `Field List'

     The thread is retrieving information for table columns.

   * `Init DB'

     The thread is selecting a default database.

   * `Kill'

     The thread is killing another thread.

   * `Long Data'

     The thread is retrieving long data in the result of executing a
     prepared statement.

   * `Ping'

     The thread is handling a server-ping request.

   * `Prepare'

     The thread is preparing a prepared statement.

   * `Processlist'

     The thread is producing information about server threads.

   * `Query'

     The thread is executing a statement.

   * `Quit'

     The thread is terminating.

   * `Refresh'

     The thread is flushing table, logs, or caches, or resetting status
     variable or replication server information.

   * `Register Slave'

     The thread is registering a slave server.

   * `Reset stmt'

     The thread is resetting a prepared statement.

   * `Set option'

     The thread is setting or resetting a client statement-execution
     option.

   * `Shutdown'

     The thread is shutting down the server.

   * `Sleep'

     The thread is waiting for the client to send a new statement to it.

   * `Statistics'

     The thread is producing server-status information.

   * `Table Dump'

     The thread is sending table contents to a slave server.

   * `Time'

     Unused.


File: manual.info,  Node: general-thread-states,  Next: delayed-insert-thread-states,  Prev: thread-commands,  Up: thread-information

7.5.5.2 General Thread States
.............................

The following list describes thread `State' values that are associated
with general query processing and not more specialized activities such
as replication. Many of these are useful only for finding bugs in the
server.

   * `After create'

     Occurs when the thread creates a table (including internal
     temporary tables), at the end of the function that creates the
     table. This state is used even if the table could not be created
     due to some error.

   * `Analyzing'

     The thread is calculating a `MyISAM' table key distributions (for
     example, for `ANALYZE TABLE').

   * `Checking table'

     The thread is performing a table check operation.

   * `cleaning up'

     The thread has processed one command and is preparing to free
     memory and reset certain state variables.

   * `closing tables'

     Means that the thread is flushing the changed table data to disk
     and closing the used tables. This should be a fast operation. If
     not, you should verify that you do not have a full disk and that
     the disk is not in very heavy use.

   * `converting HEAP to MyISAM'

     The thread is converting an internal temporary table from a
     `MEMORY' table to an on-disk `MyISAM' table.

   * `copy to tmp table'

     The thread is processing an `ALTER TABLE' statement. This state
     occurs after the table with the new structure has been created but
     before rows are copied into it.

   * `Copying to group table'

     If a statement has different `ORDER BY' and `GROUP BY' criteria,
     the rows are sorted by group and copied to a temporary table.

   * `Copying to tmp table'

     The server is copying to a temporary table in memory.

   * `Copying to tmp table on disk'

     The server is copying to a temporary table on disk. The temporary
     result set was larger than `tmp_table_size' and the thread is
     changing the temporary table from in-memory to disk-based format
     to save memory.

   * `Creating index'

     The thread is processing `ALTER TABLE ... ENABLE KEYS' for a
     `MyISAM' table.

   * `Creating sort index'

     The thread is processing a `SELECT' that is resolved using an
     internal temporary table.

   * `creating table'

     The thread is creating a table. This includes creation of
     temporary tables.

   * `Creating tmp table'

     The thread is creating a temporary table in memory or on disk. If
     the table is created in memory but later is converted to an
     on-disk table, the state during that operation will be `Copying to
     tmp table on disk'.

   * `deleting from main table'

     The server is executing the first part of a multiple-table delete.
     It is deleting only from the first table, and saving fields and
     offsets to be used for deleting from the other (reference) tables.

   * `deleting from reference tables'

     The server is executing the second part of a multiple-table delete
     and deleting the matched rows from the other tables.

   * `discard_or_import_tablespace'

     The thread is processing an `ALTER TABLE ...  DISCARD TABLESPACE'
     or `ALTER TABLE ...  IMPORT TABLESPACE' statement.

   * `end'

     This occurs at the end but before the cleanup of `ALTER TABLE',
     `CREATE VIEW', `DELETE', `INSERT', `SELECT', or `UPDATE'
     statements.

   * `Execution of init_command'

     The thread is executing statements in the value of the
     `init_command' system variable.

   * `freeing items'

     The thread has executed a command. This state is usually followed
     by `cleaning up'.

   * `Flushing tables'

     The thread is executing `FLUSH TABLES' and is waiting for all
     threads to close their tables.

   * `FULLTEXT initialization'

     The server is preparing to perform a natural-language full-text
     search.

   * `init'

     This occurs before the initialization of `ALTER TABLE', `DELETE',
     `INSERT', `SELECT', or `UPDATE' statements.

   * `Killed'

     Someone has sent a `KILL' statement to the thread and it should
     abort next time it checks the kill flag. The flag is checked in
     each major loop in MySQL, but in some cases it might still take a
     short time for the thread to die. If the thread is locked by some
     other thread, the kill takes effect as soon as the other thread
     releases its lock.

   * `Locked'

     The query is locked by another query.

   * `logging slow query'

     The thread is writing a statement to the slow-query log.

   * `login'

     The initial state for a connection thread until the client has
     been authenticated successfully.

   * `Opening tables', `Opening table'

     The thread is trying to open a table. This is should be very fast
     procedure, unless something prevents opening.  For example, an
     `ALTER TABLE' or a `LOCK TABLE' statement can prevent opening a
     table until the statement is finished.

   * `preparing'

     This state occurs during query optimization.

   * `Purging old relay logs'

     The thread is removing unneeded relay log files.

   * `query end'

     This state occurs after processing a query but before the `freeing
     items' state.

   * `Reading from net'

     The server is reading a packet from the network.

   * `Removing duplicates'

     The query was using `SELECT DISTINCT' in such a way that MySQL
     could not optimize away the distinct operation at an early stage.
     Because of this, MySQL requires an extra stage to remove all
     duplicated rows before sending the result to the client.

   * `removing tmp table'

     The thread is removing an internal temporary table after
     processing a `SELECT' statement. This state is not used if no
     temporary table was created.

   * `rename'

     The thread is renaming a table.

   * `rename result table'

     The thread is processing an `ALTER TABLE' statement, has created
     the new table, and is renaming it to replace the original table.

   * `Reopen tables'

     The thread got a lock for the table, but noticed after getting the
     lock that the underlying table structure changed. It has freed the
     lock, closed the table, and is trying to reopen it.

   * `Repair by sorting'

     The repair code is using a sort to create indexes.

   * `Repair done'

     The thread has completed a multi-threaded repair for a `MyISAM'
     table.

   * `Repair with keycache'

     The repair code is using creating keys one by one through the key
     cache. This is much slower than `Repair by sorting'.

   * `Rolling back'

     The thread is rolling back a transaction.

   * `Saving state'

     For `MyISAM' table operations such as repair or analysis, the
     thread is saving the new table state to the `.MYI' file header.
     State includes information such as number of rows, the
     `AUTO_INCREMENT' counter, and key distributions.

   * `Searching rows for update'

     The thread is doing a first phase to find all matching rows before
     updating them. This has to be done if the `UPDATE' is changing the
     index that is used to find the involved rows.

   * `Sending data'

     The thread is processing rows for a `SELECT' statement and also is
     sending data to the client.

   * `setup'

     The thread is beginning an `ALTER TABLE' operation.

   * `Sorting for group'

     The thread is doing a sort to satisfy a `GROUP BY'.

   * `Sorting for order'

     The thread is doing a sort to satisfy a `ORDER BY'.

   * `Sorting index'

     The thread is sorting index pages for more efficient access during
     a `MyISAM' table optimization operation.

   * `Sorting result'

     For a `SELECT' statement, this is similar to `Creating sort
     index', but for non-temporary tables.

   * `statistics'

     The server is calculating statistics to develop a query execution
     plan.

   * `System lock'

     The thread is going to request or is waiting for an internal or
     external system lock for the table. If this state is being caused
     by requests for external locks and you are not using multiple
     `mysqld' servers that are accessing the same tables, you can
     disable external system locks with the `--skip-external-locking'
     option. However, external locking is disabled by default, so it is
     likely that this option will have no effect.

   * `Table lock'

     The next thread state after `System lock'. The thread has acquired
     an external lock and is going to request an internal table lock.

   * `Updating'

     The thread is searching for rows to update and is updating them.

   * `updating main table'

     The server is executing the first part of a multiple-table update.
     It is updating only the first table, and saving fields and offsets
     to be used for updating the other (reference) tables.

   * `updating reference tables'

     The server is executing the second part of a multiple-table update
     and updating the matched rows from the other tables.

   * `User lock'

     The thread is going to request or is waiting for an advisory lock
     requested with a `GET_LOCK()' call.

   * `Waiting for tables', `Waiting for table'

     The thread got a notification that the underlying structure for a
     table has changed and it needs to reopen the table to get the new
     structure. However, to reopen the table, it must wait until all
     other threads have closed the table in question.

     This notification takes place if another thread has used `FLUSH
     TABLES' or one of the following statements on the table in
     question: `FLUSH TABLES TBL_NAME', `ALTER TABLE', `RENAME TABLE',
     `REPAIR TABLE', `ANALYZE TABLE', or `OPTIMIZE TABLE'.

   * `Waiting on cond'

     A generic state in which the the thread is waiting for a condition
     to become true. No specific state information is available.

   * `Writing to net'

     The server is writing a packet to the network.


File: manual.info,  Node: delayed-insert-thread-states,  Next: master-thread-states,  Prev: general-thread-states,  Up: thread-information

7.5.5.3 Delayed-Insert Thread States
....................................

These thread states are associated with processing for `DELAYED'
inserts (see *Note insert-delayed::). Some states are associated with
connection threads that process `INSERT DELAYED' statements from
clients. Other states are associated with delayed-insert handler
threads that insert the rows. There is a delayed-insert handler thread
for each table for which `INSERT DELAYED' statements are issued.

States associated with a connection thread that processes an `INSERT
DELAYED' statement from the client:

   * `allocating local table'

     The thread is preparing to feed rows to the delayed-insert handler
     thread.

   * `Creating delayed handler'

     The thread is creating a handler for `DELAYED' inserts.

   * `got handler lock'

     This occurs before the `allocating local table' state and after
     the `waiting for handler lock' state, when the connection thread
     gets access to the delayed-insert handler thread.

   * `got old table'

     This occurs after the `waiting for handler open' state. The
     delayed-insert handler thread has signaled that it has ended its
     initialization phase, which includes opening the table for delayed
     inserts.

   * `storing row into queue'

     The thread is adding a new row to the list of rows that the
     delayed-insert handler thread must insert.

   * `update'

   * `waiting for delay_list'

     This occurs during the initialization phase when the thread is
     trying to find the delayed-insert handler thread for the table,
     and before attempting to gain access to the list of delayed-insert
     threads.

   * `waiting for handler insert'

     An `INSERT DELAYED' handler has processed all pending inserts and
     is waiting for new ones.

   * `waiting for handler lock'

     This occurs before the `allocating local table' state when the
     connection thread waits for access to the delayed-insert handler
     thread.

   * `waiting for handler open'

     This occurs after the `Creating delayed handler' state and before
     the `got old table' state. The delayed-insert handler thread has
     just been started, and the connection thread is waiting for it to
     initialize.

States associated with a delayed-insert handler thread that inserts the
rows:

   * `insert'

     The state that occurs just before inserting rows into the table.

   * `reschedule'

     After inserting a number of rows, the delayed-insert thread sleeps
     to let other threads do work.

   * `upgrading lock'

     A delayed-insert handler is trying to get a lock for the table to
     insert rows.

   * `Waiting for INSERT'

     A delayed-insert handler is waiting for a connection thread to add
     rows to the queue (see `storing row into queue').


File: manual.info,  Node: master-thread-states,  Next: slave-io-thread-states,  Prev: delayed-insert-thread-states,  Up: thread-information

7.5.5.4 Replication Master Thread States
........................................

The following list shows the most common states you may see in the
`State' column for the master's `Binlog Dump' thread. If you see no
`Binlog Dump' threads on a master server, this means that replication
is not running -- that is, that no slaves are currently connected.

   * `Sending binlog event to slave'

     Binary logs consist of _events_, where an event is usually an
     update plus some other information.  The thread has read an event
     from the binary log and is now sending it to the slave.

   * `Finished reading one binlog; switching to next binlog'

     The thread has finished reading a binary log file and is opening
     the next one to send to the slave.

   * `Has sent all binlog to slave; waiting for binlog to be updated'

     The thread has read all outstanding updates from the binary logs
     and sent them to the slave. The thread is now idle, waiting for
     new events to appear in the binary log resulting from new updates
     occurring on the master.

   * `Waiting to finalize termination'

     A very brief state that occurs as the thread is stopping.


File: manual.info,  Node: slave-io-thread-states,  Next: slave-sql-thread-states,  Prev: master-thread-states,  Up: thread-information

7.5.5.5 Replication Slave I/O Thread States
...........................................

The following list shows the most common states you see in the `State'
column for a slave server I/O thread.  This state also appears in the
`Slave_IO_State' column displayed by `SHOW SLAVE STATUS', so you can
get a good view of what is happening by using that statement.

   * `Waiting for master update'

     The initial state before `Connecting to master'.

   * `Connecting to master'

     The thread is attempting to connect to the master.

   * `Checking master version'

     A state that occurs very briefly, after the connection to the
     master is established.

   * `Registering slave on master'

     A state that occurs very briefly after the connection to the
     master is established.

   * `Requesting binlog dump'

     A state that occurs very briefly, after the connection to the
     master is established. The thread sends to the master a request
     for the contents of its binary logs, starting from the requested
     binary log filename and position.

   * `Waiting to reconnect after a failed binlog dump request'

     If the binary log dump request failed (due to disconnection), the
     thread goes into this state while it sleeps, then tries to
     reconnect periodically. The interval between retries can be
     specified using the `CHANGE MASTER TO' statement or the
     `--master-connect-retry' option.

   * `Reconnecting after a failed binlog dump request'

     The thread is trying to reconnect to the master.

   * `Waiting for master to send event'

     The thread has connected to the master and is waiting for binary
     log events to arrive. This can last for a long time if the master
     is idle. If the wait lasts for `slave_net_timeout' seconds, a
     timeout occurs. At that point, the thread considers the connection
     to be broken and makes an attempt to reconnect.

   * `Queueing master event to the relay log'

     The thread has read an event and is copying it to the relay log so
     that the SQL thread can process it.

   * `Waiting to reconnect after a failed master event read'

     An error occurred while reading (due to disconnection).  The
     thread is sleeping for the number of seconds set by the `CHANGE
     MASTER TO' statement or `--master-connect-retry' option (default
     60) before attempting to reconnect.

   * `Reconnecting after a failed master event read'

     The thread is trying to reconnect to the master. When connection
     is established again, the state becomes `Waiting for master to
     send event'.

   * `Waiting for the slave SQL thread to free enough relay log space'

     You are using a non-zero `relay_log_space_limit' value, and the
     relay logs have grown large enough that their combined size
     exceeds this value. The I/O thread is waiting until the SQL thread
     frees enough space by processing relay log contents so that it can
     delete some relay log files.

   * `Waiting for slave mutex on exit'

     A state that occurs briefly as the thread is stopping.


File: manual.info,  Node: slave-sql-thread-states,  Next: slave-connection-thread-states,  Prev: slave-io-thread-states,  Up: thread-information

7.5.5.6 Replication Slave SQL Thread States
...........................................

The following list shows the most common states you may see in the
`State' column for a slave server SQL thread:

   * `Waiting for the next event in relay log'

     The initial state before `Reading event from the relay log'.

   * `Reading event from the relay log'

     The thread has read an event from the relay log so that the event
     can be processed.

   * `Has read all relay log; waiting for the slave I/O thread to
     update it'

     The thread has processed all events in the relay log files, and is
     now waiting for the I/O thread to write new events to the relay
     log.

   * `Making temp file'

     The thread is executing a `LOAD DATA INFILE' statement and is
     creating a temporary file containing the data from which the slave
     will read rows.

   * `Waiting for slave mutex on exit'

     A very brief state that occurs as the thread is stopping.

The `State' column for the I/O thread may also show the text of a
statement. This indicates that the thread has read an event from the
relay log, extracted the statement from it, and is executing it.


File: manual.info,  Node: slave-connection-thread-states,  Next: mysql-cluster-thread-states,  Prev: slave-sql-thread-states,  Up: thread-information

7.5.5.7 Replication Slave Connection Thread States
..................................................

These thread states occur on a replication slave but are associated
with connection threads, not with the I/O or SQL threads.

   * `Changing master'

     The thread is processing a `CHANGE MASTER' statement.

   * `Creating table from master dump'

     The slave is creating a table using the `CREATE TABLE' statement
     contained in the dump from the master. Used for `LOAD TABLE FROM
     MASTER' and `LOAD DATA FROM MASTER'.

   * `Killing slave'

     The thread is processing a `SLAVE STOP' statement.

   * `Opening master dump table'

     This state occurs after `Creating table from master dump'.

   * `Reading master dump table data'

     This state occurs after `Opening master dump table'.

   * `Rebuilding the index on master dump table'

     This state occurs after `Reading master dump table data'.

   * `starting slave'

     The thread is starting the slave threads after processing a
     successful `LOAD DATA FROM MASTER' load operation.


File: manual.info,  Node: mysql-cluster-thread-states,  Next: event-scheduler-thread-states,  Prev: slave-connection-thread-states,  Up: thread-information

7.5.5.8 MySQL Cluster Thread States
...................................

   * `Committing events to binlog'

   * `Opening mysql.ndb_apply_status'

   * `Processing events'

     The thread is processing events for binary logging.

   * `Processing events from schema table'

     The thread is doing the work of schema replication.

   * `Shutting down'

   * `Syncing ndb table schema operation and binlog'

     This is used to have a correct binary log of schema operations for
     NDB.

   * `Waiting for event from ndbcluster'

     The server is acting as an SQL node in a MySQL Cluster, and is
     connected to a cluster management node.

   * `Waiting for first event from ndbcluster'

   * `Waiting for ndbcluster binlog update to reach current position'

   * `Waiting for ndbcluster to start'

   * `Waiting for schema epoch'

     The thread is waiting for a schema epoch (that is, a global
     checkpoint).


File: manual.info,  Node: event-scheduler-thread-states,  Prev: mysql-cluster-thread-states,  Up: thread-information

7.5.5.9 Event Scheduler Thread States
.....................................

These states occur for the Event Scheduler thread, threads that are
created to execute scheduled events, or threads that terminate the
scheduler.

   * `Clearing'

     The scheduler thread or a thread that was executing an event is
     terminating and is about to end.

   * `Initialized'

     The scheduler thread or a thread that will execute an event has
     been initialized.

   * `Waiting for next activation'

     The scheduler has a non-empty event queue but the next activation
     is in the future.

   * `Waiting for scheduler to stop'

     The thread issued `SET GLOBAL event_scheduler=OFF' and is waiting
     for the scheduler to stop.

   * `Waiting on empty queue'

     The scheduler's event queue is empty and it is sleeping.


File: manual.info,  Node: compile-and-link-options,  Next: connection-threads,  Prev: thread-information,  Up: optimizing-the-server

7.5.6 How Compiling and Linking Affects the Speed of MySQL
----------------------------------------------------------

Most of the following tests were performed on Linux with the MySQL
benchmarks, but they should give some indication for other operating
systems and workloads.

You obtain the fastest executables when you link with `-static'.

On Linux, it is best to compile the server with `pgcc' and `-O3'. You
need about 200MB memory to compile `sql_yacc.cc' with these options,
because `gcc' or `pgcc' needs a great deal of memory to make all
functions inline. You should also set `CXX=gcc' when configuring MySQL
to avoid inclusion of the `libstdc++' library, which is not needed. Note
that with some versions of `pgcc', the resulting binary runs only on
true Pentium processors, even if you use the compiler option indicating
that you want the resulting code to work on all x586-type processors
(such as AMD).

By using a better compiler and compilation options, you can obtain a
10-30% speed increase in applications. This is particularly important
if you compile the MySQL server yourself.

When we tested both the Cygnus CodeFusion and Fujitsu compilers,
neither was sufficiently bug-free to allow MySQL to be compiled with
optimizations enabled.

The standard MySQL binary distributions are compiled with support for
all character sets. When you compile MySQL yourself, you should include
support only for the character sets that you are going to use. This is
controlled by the `--with-charset' option to `configure'.

Here is a list of some measurements that we have made:

   * If you use `pgcc' and compile everything with `-O6', the `mysqld'
     server is 1% faster than with `gcc' 2.95.2.

   * If you link dynamically (without `-static'), the result is 13%
     slower on Linux. Note that you still can use a dynamically linked
     MySQL library for your client applications. It is the server that
     is most critical for performance.

   * For a connection from a client to a server running on the same
     host, if you connect using TCP/IP rather than a Unix socket file,
     performance is 7.5% slower. (On Unix, if you connect to the
     hostname `localhost', MySQL uses a socket file by default.)

   * For TCP/IP connections from a client to a server, connecting to a
     remote server on another host is 8-11% slower than connecting to a
     server on the same host, even for connections over 100Mb/s
     Ethernet.

   * When running our benchmark tests using secure connections (all
     data encrypted with internal SSL support) performance was 55%
     slower than with unencrypted connections.

   * If you compile with `--with-debug=full', most queries are 20%
     slower. Some queries may take substantially longer; for example,
     the MySQL benchmarks run 35% slower. If you use `--with-debug'
     (without `=full'), the speed decrease is only 15%.  For a version
     of `mysqld' that has been compiled with `--with-debug=full', you
     can disable memory checking at runtime by starting it with the
     `--skip-safemalloc' option. The execution speed should then be
     close to that obtained when configuring with `--with-debug'.

   * On a Sun UltraSPARC-IIe, a server compiled with Forte 5.0 is 4%
     faster than one compiled with `gcc' 3.2.

   * On a Sun UltraSPARC-IIe, a server compiled with Forte 5.0 is 4%
     faster in 32-bit mode than in 64-bit mode.

   * Compiling with `gcc' 2.95.2 for UltraSPARC with the `-mcpu=v8
     -Wa,-xarch=v8plusa' options gives 4% more performance.

   * On Solaris 2.5.1, MIT-pthreads is 8-12% slower than Solaris native
     threads on a single processor. With greater loads or more CPUs,
     the difference should be larger.

   * Compiling on Linux-x86 using `gcc' without frame pointers
     (`-fomit-frame-pointer' or `-fomit-frame-pointer -ffixed-ebp')
     makes `mysqld' 1-4% faster.

Binary MySQL distributions for Linux that are provided by MySQL AB used
to be compiled with `pgcc'. We had to go back to regular `gcc' due to a
bug in `pgcc' that would generate binaries that do not run on AMD. We
will continue using `gcc' until that bug is resolved. In the meantime,
if you have a non-AMD machine, you can build a faster binary by
compiling with `pgcc'. The standard MySQL Linux binary is linked
statically to make it faster and more portable.


File: manual.info,  Node: connection-threads,  Next: memory-use,  Prev: compile-and-link-options,  Up: optimizing-the-server

7.5.7 How MySQL Uses Threads for Client Connections
---------------------------------------------------

Connection manager threads handle client connection requests on the
network interfaces that the server listens to. On all platforms, one
manager thread handles TCP/IP connection requests. On Unix, this
manager thread also handles Unix socket file connection requests. On
Windows, a manager thread handles shared-memory connection requests,
and another handles named-pipe connection requests. The server does not
create threads to handle interfaces that it does not listen to. For
example, a Windows server that does not have support for named-pipe
connections enabled does not create a thread to handle them.

Connection manager threads associate each client connection with a
thread dedicated to it that handles authentication and request
processing for that connection. Manager threads create a new thread
when necessary but try to avoid doing so by consulting the thread cache
first to see whether it contains a thread that can be used for the
connection. When a connection ends, its thread is returned to the
thread cache if the cache is not full.

In this connection thread model, there are as many threads as there are
clients currently connected, which has some drawbacks when server
workload must scale to handle large numbers of connections. For
example, thread creation and disposal becomes expensive. Also, each
thread requires server and kernel resources, such as stack space. To
accommodate a large number of simultaneous connections, the stack size
per thread must be kept small, leading to a situation where it is
either too small or the server consumes large amounts of memory.
Exhaustion of other resources can occur as well, and scheduling
overhead can become significant.

To control and monitor how the server manages threads that handle
client connections, several system and status variables are relevant.
(See *Note server-system-variables::, and *Note
server-status-variables::.)

The thread cache has a size determined by the `thread_cache_size'
system variable. The default value is 0 (no caching), which causes a
thread to be set up for each new connection and disposed of when the
connection terminates. Set `thread_cache_size' to N to allow N inactive
connection threads to be cached. `thread_cache_size' can be set at
server startup or changed while the server runs.

To monitor the number of threads in the cache and how many threads have
been created because a thread could not be taken from the cache,
monitor the `Threads_cached' and `Threads_created' status variables.

You can set `max_connections' at server startup or at runtime to
control the maximum number of clients that can connect simultaneously.

When the thread stack is too small, this limits the complexity of the
SQL statements which the server can handle, the recursion depth of
stored procedures, and other memory-consuming actions.  To set a stack
size of N bytes for each thread, start the server with
`--thread_stack=N'.


File: manual.info,  Node: memory-use,  Next: internal-temporary-tables,  Prev: connection-threads,  Up: optimizing-the-server

7.5.8 How MySQL Uses Memory
---------------------------

The following list indicates some of the ways that the `mysqld' server
uses memory. Where applicable, the name of the system variable relevant
to the memory use is given:

   * The key buffer is shared by all threads; its size is determined by
     the `key_buffer_size' variable. Other buffers used by the server
     are allocated as needed. See *Note server-parameters::.

   * Each thread that is used to manage client connections uses some
     thread-specific space. The following list indicates these and
     which variables control their size:

        * A stack (default 192KB, variable `thread_stack')

        * A connection buffer (variable `net_buffer_length')

        * A result buffer (variable `net_buffer_length')

     The connection buffer and result buffer both begin with a size
     given by `net_buffer_length' but are dynamically enlarged up to
     `max_allowed_packet' bytes as needed. The result buffer shrinks to
     `net_buffer_length' after each SQL statement. While a statement is
     running, a copy of the current statement string is also allocated.

   * All threads share the same base memory.

   * When a thread is no longer needed, the memory allocated to it is
     released and returned to the system unless the thread goes back
     into the thread cache. In that case, the memory remains allocated.

   * Before MySQL 5.1.4, only compressed `MyISAM' tables are memory
     mapped. As of MySQL 5.1.4, the `myisam_use_mmap' system variable
     can be set to 1 to enable memory-mapping for all `MyISAM' tables.

   * Each request that performs a sequential scan of a table allocates
     a _read buffer_ (variable `read_buffer_size').

   * When reading rows in an arbitrary sequence (for example, following
     a sort), a _random-read buffer_ (variable `read_rnd_buffer_size')
     may be allocated in order to avoid disk seeks.

   * All joins are executed in a single pass, and most joins can be
     done without even using a temporary table. Most temporary tables
     are memory-based hash tables. Temporary tables with a large row
     length (calculated as the sum of all column lengths) or that
     contain `BLOB' columns are stored on disk.

     If an internal heap table exceeds the size of `tmp_table_size',
     MySQL handles this automatically by changing the in-memory heap
     table to a disk-based `MyISAM' table as necessary. You can also
     increase the temporary table size by setting the `tmp_table_size'
     option to `mysqld', or by setting the SQL option `SQL_BIG_TABLES'
     in the client program. See *Note server-session-variables::.

     MySQL Enterprise

     Subscribers to the MySQL Enterprise Monitor are alerted when
     temporary tables exceed `tmp_table_size'. Advisors make
     recommendations for the optimum value of `tmp_table_size' based on
     actual table usage. For more information about the MySQL Enterprise
     Monitor please see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   * Most requests that perform a sort allocate a sort buffer and zero
     to two temporary files depending on the result set size. See *Note
     temporary-files::.

   * Almost all parsing and calculating is done in a local memory
     store. No memory overhead is needed for small items, so the normal
     slow memory allocation and freeing is avoided. Memory is allocated
     only for unexpectedly large strings. This is done with `malloc()'
     and `free()'.

   * For each `MyISAM' table that is opened, the index file is opened
     once; the data file is opened once for each concurrently running
     thread. For each concurrent thread, a table structure, column
     structures for each column, and a buffer of size `3 x N' are
     allocated (where N is the maximum row length, not counting `BLOB'
     columns). A `BLOB' column requires five to eight bytes plus the
     length of the `BLOB' data. The `MyISAM' storage engine maintains
     one extra row buffer for internal use.

   * For each table having `BLOB' columns, a buffer is enlarged
     dynamically to read in larger `BLOB' values. If you scan a table, a
     buffer as large as the largest `BLOB' value is allocated.

   * Handler structures for all in-use tables are saved in a cache and
     managed as a FIFO. By default, the cache has 64 entries. If a
     table has been used by two running threads at the same time, the
     cache contains two entries for the table.  See *Note table-cache::.

   * A `FLUSH TABLES' statement or `mysqladmin flush-tables' command
     closes all tables that are not in use at once and marks all in-use
     tables to be closed when the currently executing thread finishes.
     This effectively frees most in-use memory.  `FLUSH TABLES' does
     not return until all tables have been closed.

   * The server caches information in memory as a result of `GRANT',
     `CREATE USER', `CREATE SERVER', and `INSTALL PLUGIN' statements.
     This memory is not released by the corresponding `REVOKE', `DROP
     USER', `DROP SERVER', and `UNINSTALL PLUGIN' statements, so for a
     server that executes many instances of the statements that cause
     caching, there will be an increase in memory use. This cached
     memory can be freed with `FLUSH PRIVILEGES'.

`ps' and other system status programs may report that `mysqld' uses a
lot of memory. This may be caused by thread stacks on different memory
addresses.  For example, the Solaris version of `ps' counts the unused
memory between stacks as used memory. You can verify this by checking
available swap with `swap -s'.  We test `mysqld' with several
memory-leakage detectors (both commercial and Open Source), so there
should be no memory leaks.


File: manual.info,  Node: internal-temporary-tables,  Next: dns,  Prev: memory-use,  Up: optimizing-the-server

7.5.9 How MySQL Uses Internal Temporary Tables
----------------------------------------------

In some cases, the server creates internal temporary tables while
processing queries. A temporary table can be held in memory and
processed by the `MEMORY' storage engine, or stored on disk and
processed by the `MyISAM' storage engine. Temporary tables can be
created under conditions such as these:

   * If there is an `ORDER BY' clause and a different `GROUP BY'
     clause, or if the `ORDER BY' or `GROUP BY' contains columns from
     tables other than the first table in the join queue, a temporary
     table is created.

   * If you use the `SQL_SMALL_RESULT' option, MySQL uses an in-memory
     temporary table.

   * `DISTINCT' combined with `ORDER BY' may require a temporary table.

You can tell whether a query requires a temporary table by using
`EXPLAIN' and checking the `Extra' column to see whether it says `Using
temporary'. See *Note using-explain::.

Some conditions prevent the use of a `MEMORY' temporary table, in which
case the server uses a `MyISAM' table instead:

   * Presence of a `TEXT' or `BLOB' column in the table

   * Presence of any column in a `GROUP BY' or `DISTINCT' clause larger
     than 512 bytes

   * Presence of any column larger than 512 bytes in the `SELECT' list,
     if `UNION' or `UNION ALL' is used.

A temporary table that is created initially as a `MEMORY' table might
be converted to a `MyISAM' table and stored on disk if it becomes too
large. The `max_heap_table_size' system variable determines how large
`MEMORY' tables are allowed to grow. It applies to all `MEMORY' tables,
including those created with `CREATE TABLE'. However, for internal
`MEMORY' tables, the actual maximum size is determined by
`max_heap_table_size' in combination with `tmp_table_size': Whichever
value is smaller is the one that applies. If the size of an internal
`MEMORY' table exceeds the limit, MySQL automatically converts it to an
on-disk `MyISAM' table.


File: manual.info,  Node: dns,  Prev: internal-temporary-tables,  Up: optimizing-the-server

7.5.10 How MySQL Uses DNS
-------------------------

When a new client connects to `mysqld', `mysqld' spawns a new thread to
handle the request. This thread first checks whether the hostname is in
the hostname cache. If not, the thread attempts to resolve the hostname:

   * If the operating system supports the thread-safe
     `gethostbyaddr_r()' and `gethostbyname_r()' calls, the thread uses
     them to perform hostname resolution.

   * If the operating system does not support the thread-safe calls,
     the thread locks a mutex and calls `gethostbyaddr()' and
     `gethostbyname()' instead. In this case, no other thread can
     resolve hostnames that are not in the hostname cache until the
     first thread unlocks the mutex.

You can disable DNS hostname lookups by starting `mysqld' with the
`--skip-name-resolve' option. However, in this case, you can use only
IP numbers in the MySQL grant tables.

If you have a very slow DNS and many hosts, you can get more
performance by either disabling DNS lookups with `--skip-name-resolve'
or by increasing the `HOST_CACHE_SIZE' define (default value: 128) and
recompiling `mysqld'.

You can disable the hostname cache by starting the server with the
`--skip-host-cache' option. To clear the hostname cache, issue a `FLUSH
HOSTS' statement or execute the `mysqladmin flush-hosts' command.

To disallow TCP/IP connections entirely, start `mysqld' with the
`--skip-networking' option.


File: manual.info,  Node: disk-issues,  Prev: optimizing-the-server,  Up: optimization

7.6 Disk Issues
===============

* Menu:

* symbolic-links::               Using Symbolic Links

   * Disk seeks are a huge performance bottleneck. This problem becomes
     more apparent when the amount of data starts to grow so large that
     effective caching becomes impossible. For large databases where
     you access data more or less randomly, you can be sure that you
     need at least one disk seek to read and a couple of disk seeks to
     write things. To minimize this problem, use disks with low seek
     times.

   * Increase the number of available disk spindles (and thereby reduce
     the seek overhead) by either symlinking files to different disks
     or striping the disks:

        * Using symbolic links

          This means that, for `MyISAM' tables, you symlink the index
          file and data files from their usual location in the data
          directory to another disk (that may also be striped). This
          makes both the seek and read times better, assuming that the
          disk is not used for other purposes as well. See *Note
          symbolic-links::.

        * Striping

          Striping means that you have many disks and put the first
          block on the first disk, the second block on the second disk,
          and the N-th block on the (`N MOD NUMBER_OF_DISKS') disk, and
          so on. This means if your normal data size is less than the
          stripe size (or perfectly aligned), you get much better
          performance. Striping is very dependent on the operating
          system and the stripe size, so benchmark your application
          with different stripe sizes. See *Note custom-benchmarks::.

          The speed difference for striping is _very_ dependent on the
          parameters.  Depending on how you set the striping parameters
          and number of disks, you may get differences measured in
          orders of magnitude. You have to choose to optimize for
          random or sequential access.

   * For reliability, you may want to use RAID 0+1 (striping plus
     mirroring), but in this case, you need 2 x N drives to hold N
     drives of data. This is probably the best option if you have the
     money for it. However, you may also have to invest in some
     volume-management software to handle it efficiently.

   * A good option is to vary the RAID level according to how critical
     a type of data is. For example, store semi-important data that can
     be regenerated on a RAID 0 disk, but store really important data
     such as host information and logs on a RAID 0+1 or RAID N disk.
     RAID N can be a problem if you have many writes, due to the time
     required to update the parity bits.

   * On Linux, you can get much more performance by using `hdparm' to
     configure your disk's interface.  (Up to 100% under load is not
     uncommon.) The following `hdparm' options should be quite good for
     MySQL, and probably for many other applications:

          hdparm -m 16 -d 1

     Note that performance and reliability when using this command
     depend on your hardware, so we strongly suggest that you test your
     system thoroughly after using `hdparm'.  Please consult the
     `hdparm' manual page for more information. If `hdparm' is not used
     wisely, filesystem corruption may result, so back up everything
     before experimenting!

   * You can also set the parameters for the filesystem that the
     database uses:

     If you do not need to know when files were last accessed (which is
     not really useful on a database server), you can mount your
     filesystems with the `-o noatime' option. That skips updates to
     the last access time in inodes on the filesystem, which avoids
     some disk seeks.

     On many operating systems, you can set a filesystem to be updated
     asynchronously by mounting it with the `-o async' option. If your
     computer is reasonably stable, this should give you more
     performance without sacrificing too much reliability. (This flag
     is on by default on Linux.)


File: manual.info,  Node: symbolic-links,  Prev: disk-issues,  Up: disk-issues

7.6.1 Using Symbolic Links
--------------------------

* Menu:

* symbolic-links-to-databases::  Using Symbolic Links for Databases on Unix
* symbolic-links-to-tables::     Using Symbolic Links for Tables on Unix
* windows-symbolic-links::       Using Symbolic Links for Databases on Windows

You can move tables and databases from the database directory to other
locations and replace them with symbolic links to the new locations.
You might want to do this, for example, to move a database to a file
system with more free space or increase the speed of your system by
spreading your tables to different disk.

The recommended way to do this is simply to symlink databases to a
different disk. Symlink tables only as a last resort.


File: manual.info,  Node: symbolic-links-to-databases,  Next: symbolic-links-to-tables,  Prev: symbolic-links,  Up: symbolic-links

7.6.1.1 Using Symbolic Links for Databases on Unix
..................................................

On Unix, the way to symlink a database is first to create a directory
on some disk where you have free space and then to create a symlink to
it from the MySQL data directory.

     shell> mkdir /dr1/databases/test
     shell> ln -s /dr1/databases/test /PATH/TO/DATADIR

MySQL does not support linking one directory to multiple databases.
Replacing a database directory with a symbolic link works as long as
you do not make a symbolic link between databases. Suppose that you
have a database `db1' under the MySQL data directory, and then make a
symlink `db2' that points to `db1':

     shell> cd /PATH/TO/DATADIR
     shell> ln -s db1 db2

The result is that, or any table `tbl_a' in `db1', there also appears
to be a table `tbl_a' in `db2'. If one client updates `db1.tbl_a' and
another client updates `db2.tbl_a', problems are likely to occur.

However, if you really need to do this, it is possible by altering the
source file `mysys/my_symlink.c', in which you should look for the
following statement:

     if (!(MyFlags & MY_RESOLVE_LINK) ||
         (!lstat(filename,&stat_buff) && S_ISLNK(stat_buff.st_mode)))

Change the statement to this:

     if (1)


File: manual.info,  Node: symbolic-links-to-tables,  Next: windows-symbolic-links,  Prev: symbolic-links-to-databases,  Up: symbolic-links

7.6.1.2 Using Symbolic Links for Tables on Unix
...............................................

You should not symlink tables on systems that do not have a fully
operational `realpath()' call. (Linux and Solaris support
`realpath()'). You can check whether your system supports symbolic
links by issuing a `SHOW VARIABLES LIKE 'have_symlink'' statement.

Symlinks are fully supported only for `MyISAM' tables. For files used
by tables for other storage engines, you may get strange problems if
you try to use symbolic links.

The handling of symbolic links for `MyISAM' tables works as follows:

   * In the data directory, you always have the table format (`.frm')
     file, the data (`.MYD') file, and the index (`.MYI') file. The
     data file and index file can be moved elsewhere and replaced in
     the data directory by symlinks. The format file cannot.

   * You can symlink the data file and the index file independently to
     different directories.

   * You can instruct a running MySQL server to perform the symlinking
     by using the `DATA DIRECTORY' and `INDEX DIRECTORY' options to
     `CREATE TABLE'. See *Note create-table::. Alternatively, symlinking
     can be accomplished manually from the command line using `ln -s'
     if `mysqld' is not running.

   * `myisamchk' does not replace a symlink with the data file or index
     file. It works directly on the file to which the symlink points.
     Any temporary files are created in the directory where the data
     file or index file is located. The same is true for the `ALTER
     TABLE', `OPTIMIZE TABLE', and `REPAIR TABLE' statements.

   * *Note*:

     When you drop a table that is using symlinks, _both the symlink
     and the file to which the symlink points are dropped_. This is an
     extremely good reason why you should _not_ run `mysqld' as the
     system `root' or allow system users to have write access to MySQL
     database directories.

   * If you rename a table with `ALTER TABLE ...  RENAME' or `RENAME
     TABLE' and you do not move the table to another database, the
     symlinks in the database directory are renamed to the new names
     and the data file and index file are renamed accordingly.

   * If you use `ALTER TABLE ... RENAME' or `RENAME TABLE' to move a
     table to another database, the table is moved to the other database
     directory. If the table name changed, the symlinks in the new
     database directory are renamed to the new names and the data file
     and index file are renamed accordingly.

   * If you are not using symlinks, you should use the
     `--skip-symbolic-links' option to `mysqld' to ensure that no one
     can use `mysqld' to drop or rename a file outside of the data
     directory.

Table symlink operations that are not yet supported:

   * `ALTER TABLE' ignores the `DATA DIRECTORY' and `INDEX DIRECTORY'
     table options.

   * `BACKUP TABLE' and `RESTORE TABLE' do not respect symbolic links.

   * The `.frm' file must _never_ be a symbolic link (as indicated
     previously, only the data and index files can be symbolic links).
     Attempting to do this (for example, to make synonyms) produces
     incorrect results. Suppose that you have a database `db1' under
     the MySQL data directory, a table `tbl1' in this database, and in
     the `db1' directory you make a symlink `tbl2' that points to
     `tbl1':

          shell> cd /PATH/TO/DATADIR/db1
          shell> ln -s tbl1.frm tbl2.frm
          shell> ln -s tbl1.MYD tbl2.MYD
          shell> ln -s tbl1.MYI tbl2.MYI

     Problems result if one thread reads `db1.tbl1' and another thread
     updates `db1.tbl2':

        * The query cache is `fooled' (it has no way of knowing that
          `tbl1' has not been updated, so it returns outdated results).

        * `ALTER' statements on `tbl2' fail.


File: manual.info,  Node: windows-symbolic-links,  Prev: symbolic-links-to-tables,  Up: symbolic-links

7.6.1.3 Using Symbolic Links for Databases on Windows
.....................................................

Symbolic links are enabled by default for all Windows servers.  This
enables you to put a database directory on a different disk by setting
up a symbolic link to it. This is similar to the way that database
symbolic links work on Unix, although the procedure for setting up the
link is different. If you do not need symbolic links, you can disable
them using the `--skip-symbolic-links' option.

On Windows, create a symbolic link to a MySQL database by creating a
file in the data directory that contains the path to the destination
directory. The file should be named `DB_NAME.sym', where DB_NAME is the
database name.

Suppose that the MySQL data directory is `C:\mysql\data' and you want
to have database `foo' located at `D:\data\foo'. Set up a symlink using
this procedure

  1. Make sure that the `D:\data\foo' directory exists by creating it
     if necessary. If you already have a database directory named `foo'
     in the data directory, you should move it to `D:\data'. Otherwise,
     the symbolic link will be ineffective. To avoid problems, make
     sure that the server is not running when you move the database
     directory.

  2. Create a text file `C:\mysql\data\foo.sym' that contains the
     pathname `D:\data\foo\'.

After this, all tables created in the database `foo' are created in
`D:\data\foo'.

The following limitations apply to the use of `.sym' files for database
symbolic linking on Windows:

   * The symbolic link is not used if a directory with the same name as
     the database exists in the MySQL data directory.

   * The `--innodb_file_per_table' option cannot be used.

   * If you run `mysqld' as a service, you cannot use a mapped drive to
     a remote server as the destination of the symbolic link. As a
     workaround, you can use the full path (`\\servername\path\').


File: manual.info,  Node: language-structure,  Next: internationalization-localization,  Prev: optimization,  Up: Top

8 Language Structure
********************

* Menu:

* literals::                     Literal Values
* identifiers::                  Schema Object Names
* reserved-words::               Reserved Words
* user-variables::               User-Defined Variables
* comments::                     Comment Syntax

This chapter discusses the rules for writing the following elements of
SQL statements when using MySQL:

   * Literal values such as strings and numbers

   * Identifiers such as database, table, and column names

   * Reserved words

   * User-defined and system variables

   * Comments


File: manual.info,  Node: literals,  Next: identifiers,  Prev: language-structure,  Up: language-structure

8.1 Literal Values
==================

* Menu:

* string-syntax::                Strings
* number-syntax::                Numbers
* hexadecimal-values::           Hexadecimal Values
* boolean-values::               Boolean Values
* bit-field-values::             Bit-Field Values
* null-values::                  `NULL' Values

This section describes how to write literal values in MySQL. These
include strings, numbers, hexadecimal values, boolean values, and
`NULL'. The section also covers the various nuances and `gotchas' that
you may run into when dealing with these basic types in MySQL.


File: manual.info,  Node: string-syntax,  Next: number-syntax,  Prev: literals,  Up: literals

8.1.1 Strings
-------------

A string is a sequence of bytes or characters, enclosed within either
single quote (``''') or double quote (``"'') characters.  Examples:

     'a string'
     "another string"

If the `ANSI_QUOTES' SQL mode is enabled, string literals can be quoted
only within single quotes because a string quoted within double quotes
is interpreted as an identifier.

A _binary string_ is a string of bytes that has no character set or
collation. A _non-binary string_ is a string of characters that has a
character set and collation. For both types of strings, comparisons are
based on the numeric values of the string unit.  For binary strings,
the unit is the byte. For non-binary strings the unit is the character
and some character sets allow multi-byte characters. Character value
ordering is a function of the string collation.

String literals may have an optional character set introducer and
`COLLATE' clause:

     [_CHARSET_NAME]'STRING' [COLLATE COLLATION_NAME]

Examples:

     SELECT _latin1'STRING';
     SELECT _latin1'STRING' COLLATE latin1_danish_ci;

You can use `N'LITERAL'' (or `n'LITERAL'') to create a string in the
national character set. These statements are equivalent:

     SELECT N'some text';
     SELECT n'some text';
     SELECT _utf8'some text';

For more information about these forms of string syntax, see *Note
charset-literal::, and *Note charset-national::.

Within a string, certain sequences have special meaning. Each of these
sequences begins with a backslash (``\''), known as the _escape
character_. MySQL recognizes the following escape sequences:

`\0'    An ASCII 0 (`NUL') character.
`\''    A single quote (``''') character.
`\"'    A double quote (``"'') character.
`\b'    A backspace character.
`\n'    A newline (linefeed) character.
`\r'    A carriage return character.
`\t'    A tab character.
`\Z'    ASCII 26 (Control-Z). See note following the table.
`\\'    A backslash (``\'') character.
`\%'    A ``%'' character. See note following the table.
`\_'    A ``_'' character. See note following the table.

For all other escape sequences, backslash is ignored. That is, the
escaped character is interpreted as if it was not escaped.  For
example, ``\x'' is just ``x''.

These sequences are case sensitive. For example, ``\b'' is interpreted
as a backspace, but ``\B'' is interpreted as ``B''.

The ASCII 26 character can be encoded as ``\Z'' to enable you to work
around the problem that ASCII 26 stands for END-OF-FILE on Windows.
ASCII 26 within a file causes problems if you try to use `mysql DB_NAME
< FILE_NAME'.

Escape processing is done according to the character set indicated by
the `character_set_connection' system variable. This is true even for
strings that are preceded by an introducer that indicates a different
character set, as discussed in *Note charset-literal::.

The ``\%'' and ``\_'' sequences are used to search for literal
instances of ``%'' and ``_'' in pattern-matching contexts where they
would otherwise be interpreted as wildcard characters. See the
description of the `LIKE' operator in *Note
string-comparison-functions::. If you use ``\%'' or ``\_'' in
non-pattern-matching contexts, they evaluate to the strings ``\%'' and
``\_'', not to ``%'' and ``_''.

There are several ways to include quote characters within a string:

   * A ``''' inside a string quoted with ``''' may be written as ``''''.

   * A ``"'' inside a string quoted with ``"'' may be written as ``""''.

   * Precede the quote character by an escape character (``\'').

   * A ``''' inside a string quoted with ``"'' needs no special
     treatment and need not be doubled or escaped. In the same way,
     ``"'' inside a string quoted with ``''' needs no special treatment.

The following `SELECT' statements demonstrate how quoting and escaping
work:

     mysql> SELECT 'hello', '"hello"', '""hello""', 'hel''lo', '\'hello';
     +-------+---------+-----------+--------+--------+
     | hello | "hello" | ""hello"" | hel'lo | 'hello |
     +-------+---------+-----------+--------+--------+

     mysql> SELECT "hello", "'hello'", "''hello''", "hel""lo", "\"hello";
     +-------+---------+-----------+--------+--------+
     | hello | 'hello' | ''hello'' | hel"lo | "hello |
     +-------+---------+-----------+--------+--------+

     mysql> SELECT 'This\nIs\nFour\nLines';
     +--------------------+
     | This
     Is
     Four
     Lines |
     +--------------------+

     mysql> SELECT 'disappearing\ backslash';
     +------------------------+
     | disappearing backslash |
     +------------------------+

If you want to insert binary data into a string column (such as a
`BLOB' column), the following characters must be represented by escape
sequences:

`NUL'   `NUL' byte (ASCII 0). Represent this character by ``\0'' (a
        backslash followed by an ASCII ``0'' character).
`\'     Backslash (ASCII 92). Represent this character by ``\\''.
`''     Single quote (ASCII 39). Represent this character by ``\'''.
`"'     Double quote (ASCII 34). Represent this character by ``\"''.

When writing application programs, any string that might contain any of
these special characters must be properly escaped before the string is
used as a data value in an SQL statement that is sent to the MySQL
server. You can do this in two ways:

   * Process the string with a function that escapes the special
     characters. In a C program, you can use the *Note
     `mysql_real_escape_string()': mysql-real-escape-string.  C API
     function to escape characters. See *Note
     mysql-real-escape-string::. The Perl DBI interface provides a
     `quote' method to convert special characters to the proper escape
     sequences.  See *Note perl::. Other language interfaces may
     provide a similar capability.

   * As an alternative to explicitly escaping special characters, many
     MySQL APIs provide a placeholder capability that enables you to
     insert special markers into a statement string, and then bind data
     values to them when you issue the statement. In this case, the API
     takes care of escaping special characters in the values for you.


File: manual.info,  Node: number-syntax,  Next: hexadecimal-values,  Prev: string-syntax,  Up: literals

8.1.2 Numbers
-------------

Integers are represented as a sequence of digits. Floats use ``.'' as a
decimal separator.  Either type of number may be preceded by ``-'' or
``+'' to indicate a negative or positive value, respectively

Examples of valid integers:

     1221
     0
     -32

Examples of valid floating-point numbers:

     294.42
     -32032.6809e+10
     148.00

An integer may be used in a floating-point context; it is interpreted
as the equivalent floating-point number.


File: manual.info,  Node: hexadecimal-values,  Next: boolean-values,  Prev: number-syntax,  Up: literals

8.1.3 Hexadecimal Values
------------------------

MySQL supports hexadecimal values, written using `X'VAL'', `x'VAL'', or
`0xVAL' format, where VAL contains hexadecimal digits (`0..9', `A..F').
Lettercase of the digits does not matter. For values written using
`X'VAL'' or `x'VAL'' format, VAL must contain an even number of digits.
For values written using `0xVAL syntax', values that contain an odd
number of digits are treated as having an extra leading `0'. For
example, `0x0a' and `0xaaa' are interpreted as `0x0a' and `0x0aaa'.

In numeric contexts, hexadecimal values act like integers (64-bit
precision). In string contexts, they act like binary strings, where
each pair of hex digits is converted to a character:

     mysql> SELECT X'4D7953514C';
             -> 'MySQL'
     mysql> SELECT 0x0a+0;
             -> 10
     mysql> SELECT 0x5061756c;
             -> 'Paul'

The default type of a hexadecimal value is a string. If you want to
ensure that the value is treated as a number, you can use `CAST(... AS
UNSIGNED)':

     mysql> SELECT 0x41, CAST(0x41 AS UNSIGNED);
             -> 'A', 65

The `X'HEXSTRING'' syntax is based on standard SQL. The `0x' syntax is
based on ODBC. Hexadecimal strings are often used by ODBC to supply
values for `BLOB' columns.

You can convert a string or a number to a string in hexadecimal format
with the `HEX()' function:

     mysql> SELECT HEX('cat');
             -> '636174'
     mysql> SELECT 0x636174;
             -> 'cat'


File: manual.info,  Node: boolean-values,  Next: bit-field-values,  Prev: hexadecimal-values,  Up: literals

8.1.4 Boolean Values
--------------------

The constants `TRUE' and `FALSE' evaluate to `1' and `0', respectively.
The constant names can be written in any lettercase.

     mysql> SELECT TRUE, true, FALSE, false;
             -> 1, 1, 0, 0


File: manual.info,  Node: bit-field-values,  Next: null-values,  Prev: boolean-values,  Up: literals

8.1.5 Bit-Field Values
----------------------

Bit-field values can be written using `b'VALUE'' or `0bVALUE' notation.
VALUE is a binary value written using zeros and ones.

Bit-field notation is convenient for specifying values to be assigned
to `BIT' columns:

     mysql> CREATE TABLE t (b BIT(8));
     mysql> INSERT INTO t SET b = b'11111111';
     mysql> INSERT INTO t SET b = b'1010';
     mysql> INSERT INTO t SET b = b'0101';

Bit values are returned as binary values. To display them in printable
form, add 0 or use a conversion function such as `BIN()'. High-order 0
bits are not displayed in the converted value.

     mysql> SELECT b+0, BIN(b+0), OCT(b+0), HEX(b+0) FROM t;
     +------+----------+----------+----------+
     | b+0  | BIN(b+0) | OCT(b+0) | HEX(b+0) |
     +------+----------+----------+----------+
     |  255 | 11111111 | 377      | FF       |
     |   10 | 1010     | 12       | A        |
     |    5 | 101      | 5        | 5        |
     +------+----------+----------+----------+

Bit values assigned to user variables are treated as binary strings. To
assign a bit value as a number to a user variable, use `CAST()' or `+0':

     mysql> SET @v1 = b'1000001';
     mysql> SET @v2 = CAST(b'1000001' AS UNSIGNED), @v3 = b'1000001'+0;
     mysql> SELECT @v1, @v2, @v3;
     +------+------+------+
     | @v1  | @v2  | @v3  |
     +------+------+------+
     | A    |   65 |   65 |
     +------+------+------+


File: manual.info,  Node: null-values,  Prev: bit-field-values,  Up: literals

8.1.6 `NULL' Values
-------------------

The `NULL' value means `no data.' `NULL' can be written in any
lettercase. A synonym is `\N' (case sensitive).

For text file import or export operations performed with `LOAD DATA
INFILE' or `SELECT ... INTO OUTFILE', `NULL' is represented by the `\N'
sequence. See *Note load-data::.

Be aware that the `NULL' value is different from values such as `0' for
numeric types or the empty string for string types. For more
information, see *Note problems-with-null::.


File: manual.info,  Node: identifiers,  Next: reserved-words,  Prev: literals,  Up: language-structure

8.2 Schema Object Names
=======================

* Menu:

* identifier-qualifiers::        Identifier Qualifiers
* identifier-case-sensitivity::  Identifier Case Sensitivity
* identifier-mapping::           Mapping of Identifiers to Filenames
* function-resolution::          Function Name Parsing and Resolution

Certain objects within MySQL, including database, table, index, column,
alias, view, stored procedure, partition, tablespace, and other object
names are known as identifiers. This section describes the allowable
syntax for identifiers in MySQL.  *Note identifier-case-sensitivity::,
describes which types of identifiers are case sensitive and under what
conditions.

An identifier may be quoted or unquoted. If an identifier contains
special characters or is a reserved word, you _must_ quote it whenever
you refer to it. The set of alphanumeric characters from the current
character set, ``_'', and ``$'' are not special. Reserved words are
listed at *Note reserved-words::. (Exception: A reserved word that
follows a period in a qualified name must be an identifier, so it need
not be quoted.)

The identifier quote character is the backtick (```''):

     mysql> SELECT * FROM `select` WHERE `select`.id > 100;

If the `ANSI_QUOTES' SQL mode is enabled, it is also allowable to quote
identifiers within double quotes:

     mysql> CREATE TABLE "test" (col INT);
     ERROR 1064: You have an error in your SQL syntax...
     mysql> SET sql_mode='ANSI_QUOTES';
     mysql> CREATE TABLE "test" (col INT);
     Query OK, 0 rows affected (0.00 sec)

The `ANSI_QUOTES' mode causes the server to interpret double-quoted
strings as identifiers. Consequently, when this mode is enabled, string
literals must be enclosed within single quotes. They cannot be enclosed
within double quotes. The server SQL mode is controlled as described in
*Note server-sql-mode::.

Identifier quote characters can be included within an identifier if you
quote the identifier. If the character to be included within the
identifier is the same as that used to quote the identifier itself,
then you need to double the character. The following statement creates
a table named `a`b' that contains a column named `c"d':

     mysql> CREATE TABLE `a``b` (`c"d` INT);

Aliases may be quoted either as identifiers or as strings:

     mysql> SELECT 1 AS `one`, 2 AS 'two';
     +-----+-----+
     | one | two |
     +-----+-----+
     |   1 |   2 |
     +-----+-----+

Identifiers may begin with a digit but unless quoted may not consist
solely of digits.

It is recommended that you do not use names of the form `Me' or `MeN',
where M and N are integers. For example, avoid using `1e' or `2e2' as
identifiers, because an expression such as `1e+3' is ambiguous.
Depending on context, it might be interpreted as the expression `1e +
3' or as the number `1e+3'.

Be careful when using `MD5()' to produce table names because it can
produce names in illegal or ambiguous formats such as those just
described.

A user variable cannot be used directly in an SQL statement as an
identifier or as part of an identifier. See *Note user-variables::, for
more information and examples of workarounds.

There are some restrictions on the characters that may appear in
identifiers:

   * No identifier can contain ASCII 0 (`0x00') or a byte with a value
     of 255.

   * Database, table, and column names should not end with space
     characters.

   * Before MySQL 5.1.6, database and table names cannot contain ``/'',
     ``\'', ``.'', or characters that are not allowed in filenames.

As of MySQL 5.1.6, special characters in database and table names are
encoded in the corresponding filesystem names as described in *Note
identifier-mapping::. If you have databases or tables from an older
version of MySQL that contain special characters and for which the
underlying directory names or filenames have not been updated to use
the new encoding, the server displays their names with a prefix of
`#mysql50#'. For information about referring to such names or
converting them to the newer encoding, see that section.

The following table describes the maximum length for each type of
identifier.

*Identifier**Maximum
            Length
            (characters)*
Database    64
Table       64
Column      64
Index       64
Stored      64
Function    
or          
Procedure   
Trigger     64
View        64
Event       64
Tablespace  64
Log File    64
Group       
Alias       255

Identifiers are stored using Unicode (UTF-8). This applies to
identifiers in table definitions that are stored in `.frm' files and to
identifiers stored in the grant tables in the `mysql' database. The
sizes of the identifier string columns in the grant tables are measured
in characters. You can use multi-byte characters without reducing the
number of characters allowed for values stored in these columns,
something not true prior to MySQL 4.1. The allowable Unicode characters
are those in the Basic Multilingual Plane (BMP). Supplementary
characters are not allowed.


File: manual.info,  Node: identifier-qualifiers,  Next: identifier-case-sensitivity,  Prev: identifiers,  Up: identifiers

8.2.1 Identifier Qualifiers
---------------------------

MySQL allows names that consist of a single identifier or multiple
identifiers. The components of a multiple-part name must be separated
by period (``.'') characters. The initial parts of a multiple-part name
act as qualifiers that affect the context within which the final
identifier is interpreted.

In MySQL, you can refer to a table column using any of the following
forms:

*Column Reference*     *Meaning*
COL_NAME               The column COL_NAME from whichever table used in
                       the statement contains a column of that name.
TBL_NAME.COL_NAME      The column COL_NAME from table TBL_NAME of the
                       default database.
DB_NAME.TBL_NAME.COL_NAMEThe column COL_NAME from table TBL_NAME of the
                       database DB_NAME.

If any components of a multiple-part name require quoting, quote them
individually rather than quoting the name as a whole. For example,
write ``my-table`.`my-column`', not ``my-table.my-column`'.

A reserved word that follows a period in a qualified name must be an
identifier, so in that context it need not be quoted.

You need not specify a TBL_NAME or DB_NAME.TBL_NAME prefix for a column
reference in a statement unless the reference would be ambiguous.
Suppose that tables `t1' and `t2' each contain a column `c', and you
retrieve `c' in a `SELECT' statement that uses both `t1' and `t2'. In
this case, `c' is ambiguous because it is not unique among the tables
used in the statement. You must qualify it with a table name as `t1.c'
or `t2.c' to indicate which table you mean. Similarly, to retrieve from
a table `t' in database `db1' and from a table `t' in database `db2' in
the same statement, you must refer to columns in those tables as
`db1.t.COL_NAME' and `db2.t.COL_NAME'.

The syntax `.TBL_NAME' means the table TBL_NAME in the default
database. This syntax is accepted for ODBC compatibility because some
ODBC programs prefix table names with a ``.'' character.


File: manual.info,  Node: identifier-case-sensitivity,  Next: identifier-mapping,  Prev: identifier-qualifiers,  Up: identifiers

8.2.2 Identifier Case Sensitivity
---------------------------------

In MySQL, databases correspond to directories within the data
directory. Each table within a database corresponds to at least one
file within the database directory (and possibly more, depending on the
storage engine). Triggers also correspond to files. Consequently, the
case sensitivity of the underlying operating system plays a part in the
case sensitivity of database and table names. This means database,
table, and trigger names are not case sensitive in Windows, but are case
sensitive in most varieties of Unix. One notable exception is Mac OS X,
which is Unix-based but uses a default filesystem type (HFS+) that is
not case sensitive. However, Mac OS X also supports UFS volumes, which
are case sensitive just as on any Unix. See *Note extensions-to-ansi::.
The `lower_case_table_names' system variable also affects how the
server handles identifier case sensitivity, as described later in this
section.

MySQL Enterprise

`lower_case_table_names' is just one of the system variables monitored
by the MySQL Enterprise Monitor.  For information about subscribing to
this service, see
`http://www.mysql.com/products/enterprise/advisors.html'.

*Note*:

Although database, table, and trigger names are not case sensitive on
some platforms, you should not refer to one of these using different
cases within the same statement. The following statement would not work
because it refers to a table both as `my_table' and as `MY_TABLE':

     mysql> SELECT * FROM my_table WHERE MY_TABLE.col=1;

Column, index, stored routine, and event names are not case sensitive
on any platform, nor are column aliases.

However, names of triggers and logfile groups are case sensitive. This
differs from standard SQL.

By default, table aliases are case sensitive on Unix, but not so on
Windows or Mac OS X. The following statement would not work on Unix,
because it refers to the alias both as `a' and as `A':

     mysql> SELECT COL_NAME FROM TBL_NAME AS a
         -> WHERE a.COL_NAME = 1 OR A.COL_NAME = 2;

However, this same statement is permitted on Windows. To avoid problems
caused by such differences, it is best to adopt a consistent
convention, such as always creating and referring to databases and
tables using lowercase names. This convention is recommended for
maximum portability and ease of use.

How table and database names are stored on disk and used in MySQL is
affected by the `lower_case_table_names' system variable, which you can
set when starting `mysqld'.  `lower_case_table_names' can take the
values shown in the following table. This variable does _not_ affect
case sensitivity of trigger identifiers. On Unix, the default value of
`lower_case_table_names' is 0. On Windows the default value is 1. On
Mac OS X, the default value is 2.

*Value* *Meaning*
`0'     Table and database names are stored on disk using the lettercase
        specified in the `CREATE TABLE' or `CREATE DATABASE' statement.
        Name comparisons are case sensitive. Note that if you force this
        variable to 0 with `--lower-case-table-names=0' on a
        case-insensitive filesystem and access `MyISAM' tablenames using
        different lettercases, index corruption may result.
`1'     Table names are stored in lowercase on disk and name comparisons
        are not case sensitive. MySQL converts all table names to
        lowercase on storage and lookup. This behavior also applies to
        database names and table aliases.
`2'     Table and database names are stored on disk using the lettercase
        specified in the `CREATE TABLE' or `CREATE DATABASE' statement,
        but MySQL converts them to lowercase on lookup. Name comparisons
        are not case sensitive. This works _only_ on filesystems that
        are not case sensitive! `InnoDB' table names are stored in
        lowercase, as for `lower_case_table_names=1'.

If you are using MySQL on only one platform, you do not normally have
to change the `lower_case_table_names' variable from its default value.
However, you may encounter difficulties if you want to transfer tables
between platforms that differ in filesystem case sensitivity. For
example, on Unix, you can have two different tables named `my_table'
and `MY_TABLE', but on Windows these two names are considered
identical. To avoid data transfer problems arising from lettercase of
database or table names, you have two options:

   * Use `lower_case_table_names=1' on all systems. The main
     disadvantage with this is that when you use `SHOW TABLES' or `SHOW
     DATABASES', you do not see the names in their original lettercase.

   * Use `lower_case_table_names=0' on Unix and
     `lower_case_table_names=2' on Windows. This preserves the
     lettercase of database and table names. The disadvantage of this
     is that you must ensure that your statements always refer to your
     database and table names with the correct lettercase on Windows.
     If you transfer your statements to Unix, where lettercase is
     significant, they do not work if the lettercase is incorrect.

     *Exception*: If you are using `InnoDB' tables and you are trying
     to avoid these data transfer problems, you should set
     `lower_case_table_names' to 1 on all platforms to force names to
     be converted to lowercase.

If you plan to set the `lower_case_table_names' system variable to 1 on
Unix, you must first convert your old database and table names to
lowercase before stopping `mysqld' and restarting it with the new
variable setting.

Object names may be considered duplicates if their uppercase forms are
equal according to a binary collation. That is true for names of
cursors, conditions, functions, procedures, savepoints, and routine
local variables. It is not true for names of columns, constraints,
databases, partitions, statements prepared with `PREPARE', tables,
triggers, users, and user-defined variables.


File: manual.info,  Node: identifier-mapping,  Next: function-resolution,  Prev: identifier-case-sensitivity,  Up: identifiers

8.2.3 Mapping of Identifiers to Filenames
-----------------------------------------

There is a correspondence between database and table identifiers and
names in the filesystem. For the basic structure, MySQL represents each
database as a directory in the data directory, and each table by one or
more files in the appropriate database directory. For the table format
files (`.FRM'), the data is always stored in this structure and
location.

For the data and index files, the exact representation on disk is
storage engine specific. These files may be stored in the same location
as the `FRM' files, or the information may be stored separate file.
`InnoDB' data is stored in the InnoDB data files. If you are using
tablespaces with `InnoDB', then the specific tablespace files you
create are used instead.

Before MySQL 5.1.6, there are some limitations on the characters that
can be used in identifiers for database objects that correspond to
filesystem objects. For example, pathname separator characters are
disallowed, and ``.'' is disallowed because it begins the extension for
table files.

As of MySQL 5.1.6, any character is legal in database or table
identifiers except ASCII NUL (`0x00'). MySQL encodes any characters
that are problematic in the corresponding filesystem objects when it
creates database directories or table files:

   * Basic Latin letters (`a..zA..Z') and digits (`0..9') are encoded
     as is. Consequently, their case sensitivity directly depends on
     filesystem features.

   * All other national letters from alphabets that have
     uppercase/lowercase mapping are encoded as follows:

          Code range Pattern            Number   Used Unused  Blocks
          -----------------------------------------------------------------------------
          00C0..017F [@][0..4][g..z] 5*20= 100   97     3  Latin1 Supplement + Ext A
          0370..03FF [@][5..9][g..z] 5*20= 100   88    12  Greek + Coptic
          0400..052F [@][g..z][0..6] 20*7= 140  140   137  Cyrillic
          0530..058F [@][g..z][7..8] 20*2=  40   38     2  Armenian
          2160..217F [@][g..z][9]    20*1=  20   16     4  Number Forms
          0180..02AF [@][g..z][a..k] 28*11=220  203    17  Latin Ext B + IPA
          1E00..0EFF [@][g..z][l..r] 20*7= 140  136     4  Latin Additional Extended
          1F00..1FFF [@][g..z][s..z] 20*8= 160  144    16  Greek Extended
          ....  .... [@][a..f][g..z] 6*20= 120    0   120  RESERVED
          24B6..24E9 [@][@][a..z]           26   26     0  Enclosed Alphanumerics
          FF21..FF5A [@][a..z][@]           26   26     0  Full Width forms

     One of the bytes in the sequence encodes lettercase. For example:
     `LATIN CAPITAL LETTER A WITH GRAVE' is encoded as `@0G', whereas
     `LATIN SMALL LETTER A WITH GRAVE' is encoded as `@0g'. Here the
     third byte (`G' or `g') indicates lettercase. (On a
     case-insensitive filesystem, both letters will be treated as the
     same.)

     For some blocks, such as Cyrillic, the second byte determines
     lettercase. For other blocks, such as Latin1 Supplement, the third
     byte determines lettercase. If two bytes in the sequence are
     letters (as in Greek Extended), the leftmost letter character
     stands for lettercase. All other letter bytes must be in lowercase.

   * All non-letter characters, as well as letters from alphabets that
     do not have uppercase/lowercase mapping (such as Hebrew) are
     encoded using hexadecimal representation using lowercase letters
     for hex digits `a..f':

          0x003F -> @003f
          0xFFFF -> @ffff

     The hexadecimal values correspond to character values in the
     `ucs2' double-byte character set.

On Windows, some names such as `nul', `prn', and `aux' cannot be used
as filenames because they are reserved as device names. As of MySQL
5.1.10, these are allowable names in MySQL. They are encoded by
appending `@@@' to the name when the server creates the corresponding
file or directory. This occurs on all platforms for portability of the
corresponding database object between platforms.

If you have databases or tables from a version of MySQL older than
5.1.6 that contain special characters and for which the underlying
directory names or filenames have not been updated to use the new
encoding, the server displays their names with a prefix of `#mysql50#'
in the output from `INFORMATION_SCHEMA' tables or `SHOW' statements.
For example, if you have a table named `a@b' and its name encoding has
not been updated, `SHOW TABLES' displays it like this:

     mysql> SHOW TABLES;
     +----------------+
     | Tables_in_test |
     +----------------+
     | #mysql50#a@b   |
     +----------------+

To refer to such a name for which the encoding has not been updated,
you must supply the `#mysql50#' prefix:

     mysql> SHOW COLUMNS FROM `a@b`;
     ERROR 1146 (42S02): Table 'test.a@b' doesn't exist

     mysql> SHOW COLUMNS FROM `#mysql50#a@b`;
     +-------+---------+------+-----+---------+-------+
     | Field | Type    | Null | Key | Default | Extra |
     +-------+---------+------+-----+---------+-------+
     | i     | int(11) | YES  |     | NULL    |       |
     +-------+---------+------+-----+---------+-------+

To update old names to eliminate the need to use the special prefix to
refer to them, re-encode them with `mysqlcheck'. The following command
updates all names to the new encoding:

     shell> mysqlcheck --check-upgrade --fix-db-names --fix-table-names --all-databases

To check only specific databases or tables, omit `--all-databases' and
provide the appropriate database or table arguments. For information
about `mysqlcheck' invocation syntax, see *Note mysqlcheck::.

*Note*:

The `#mysql50#' prefix is intended only to be used internally by the
server. You should not create databases or tables with names that use
this prefix.

Also, `mysqlcheck' cannot fix names that contain literal instances of
the `@' character that is used for encoding special characters. If you
have databases or tables that contain this character, use `mysqldump'
to dump them before upgrading to MySQL 5.1.6 or later, and then reload
the dump file after upgrading.


File: manual.info,  Node: function-resolution,  Prev: identifier-mapping,  Up: identifiers

8.2.4 Function Name Parsing and Resolution
------------------------------------------

MySQL 5.1 supports built-in (native) functions, user-defined functions
(UDFs), and stored functions. This section describes how the server
recognizes whether the name of a built-in function is used as a
function call or as an identifier, and how the server determines which
function to use in cases when functions of different types exist with a
given name.

*Built-In Function Name Parsing*

The parser uses default rules for parsing names of built-in functions.
These rules can be changed by enabling the `IGNORE_SPACE' SQL mode.

When the parser encounters a word that is the name of a built-in
function, it must determine whether the name signifies a function call
or is instead a non-expression reference to an identifier such as a
table or column name. For example, in the following statements, the
first reference to `count' is a function call, whereas the second
reference is a table name:

     SELECT COUNT(*) FROM mytable;
     CREATE TABLE count (i INT);

The parser should recognize the name of a built-in function as
indicating a function call only when parsing what is expected to be an
expression. That is, in non-expression context, function names are
permitted as identifiers.

However, some built-in functions have special parsing or implementation
considerations, so the parser uses the following rules by default to
distinguish whether their names are being used as function calls or as
identifiers in non-expression context:

   * To use the name as a function call in an expression, there must be
     no whitespace between the name and the following ``('' parenthesis
     character.

   * Conversely, to use the function name as an identifier, it must not
     be followed immediately by a parenthesis.

The requirement that function calls be written with no whitespace
between the name and the parenthesis applies only to the built-in
functions that have special considerations.  `COUNT' is one such name.
The exact list of function names for which following whitespace
determines their interpretation are those listed in the
`sql_functions[]' array of the `sql/lex.h' source file. Before MySQL
5.1, these are are rather numerous (about 200), so you may find it
easiest to treat the no-whitespace requirement as applying to all
function calls. In MySQL 5.1, parser improvements reduce to about 30
the number of affected function names.

For functions not listed in the `sql_functions[]') array, whitespace
does not matter. They are interpreted as function calls only when used
in expression context and may be used freely as identifiers otherwise.
`ASCII' is one such name. However, for these non-affected function
names, interpretation may vary in expression context: `FUNC_NAME ()' is
interpreted as a built-in function if there is one with the given name;
if not, `FUNC_NAME ()' is interpreted as a user-defined function or
stored function if one exists with that name.

The `IGNORE_SPACE' SQL mode can be used to modify how the parser treats
function names that are whitespace-sensitive:

   * With `IGNORE_SPACE' disabled, the parser interprets the name as a
     function call when there is no whitespace between the name and the
     following parenthesis.  This occurs even when the function name is
     used in non-expression context:

          mysql> CREATE TABLE count(i INT);
          ERROR 1064 (42000): You have an error in your SQL syntax ...
          near 'count(i INT)'

     To eliminate the error and cause the name to be treated as an
     identifier, either use whitespace following the name or write it
     as a quoted identifier (or both):

          CREATE TABLE count (i INT);
          CREATE TABLE `count`(i INT);
          CREATE TABLE `count` (i INT);

   * With `IGNORE_SPACE' enabled, the parser loosens the requirement
     that there be no whitespace between the function name and the
     following parenthesis. This provides more flexibility in writing
     function calls. For example, either of the following function
     calls are legal:

          SELECT COUNT(*) FROM mytable;
          SELECT COUNT (*) FROM mytable;

     However, enabling `IGNORE_SPACE' also has the side effect that the
     parser treats the affected function names as reserved words (see
     *Note reserved-words::). This means that a space following the
     name no longer signifies its use as an identifier. The name can be
     used in function calls with or without following whitespace, but
     causes a syntax error in non-expression context unless it is
     quoted. For example, with `IGNORE_SPACE' enabled, both of the
     following statements fail with a syntax error because the parser
     interprets `count' as a reserved word:

          CREATE TABLE count(i INT);
          CREATE TABLE count (i INT);

     To use the function name in non-expression context, write it as a
     quoted identifier:

          CREATE TABLE `count`(i INT);
          CREATE TABLE `count` (i INT);

To enable the `IGNORE_SPACE' SQL mode, use this statement:

     SET sql_mode = 'IGNORE_SPACE';

`IGNORE_SPACE' is also enabled by certain other composite modes such as
`ANSI' that include it in their value:

     SET sql_mode = 'ANSI';

Check *Note server-sql-mode::, to see which composite modes enable
`IGNORE_SPACE'.

To minimize the dependency of SQL code on the `IGNORE_SPACE' setting,
use these guidelines:

   * Avoid creating UDFs or stored functions that have the same name as
     a built-in function.

   * Avoid using function names in non-expression context. For example,
     these statements use `count' (one of the affected function names
     affected by `IGNORE_SPACE'), so they fail with or without
     whitespace following the name if `IGNORE_SPACE' is enabled:

          CREATE TABLE count(i INT);
          CREATE TABLE count (i INT);

     If you must use a function name in non-expression context, write
     it as a quoted identifier:

          CREATE TABLE `count`(i INT);
          CREATE TABLE `count` (i INT);

The number of function names affected by `IGNORE_SPACE' was reduced
significantly in MySQL 5.1.13, from about 200 to about 30. As of MySQL
5.1.13, only the following functions are still affected by the
`IGNORE_SPACE' setting:

`ADDDATE'          `BIT_AND'          `BIT_OR'           `BIT_XOR'
`CAST'             `COUNT'            `CURDATE'          `CURTIME'
`DATE_ADD'         `DATE_SUB'         `EXTRACT'          `GROUP_CONCAT'
`MAX'              `MID'              `MIN'              `NOW'
`POSITION'         `SESSION_USER'     `STD'              `STDDEV'
`STDDEV_POP'       `STDDEV_SAMP'      `SUBDATE'          `SUBSTR'
`SUBSTRING'        `SUM'              `SYSDATE'          `SYSTEM_USER'
`TRIM'             `VARIANCE'         `VAR_POP'          `VAR_SAMP'

For earlier versions of MySQL, check the contents of the
`sql_functions[]' array in the `sql/lex.h' source file to see which
functions are affected by `IGNORE_SPACE'.

*Incompatibility warning*: The change in MySQL 5.1.13 that reduces the
number of function names affected by `IGNORE_SPACE' improves the
consistency of parser operation. However, it also introduces the
possibility of incompatibility for old SQL code that relies on the
following conditions:

   * `IGNORE_SPACE' is disabled.

   * The presence or absence of whitespace following a function name is
     used to distinguish between a built-in function and stored
     function that have the same name, such as `PI()' versus `PI ()'.

For functions that are no longer affected by `IGNORE_SPACE' as of MySQL
5.1.13, that strategy no longer works. Either of the following
approaches can be used if you have code that is subject to the preceding
incompatibility:

   * If a stored function has a name that conflicts with a built-in
     function, refer to the stored function with a schema name
     qualifier, regardless of whether whitespace is present. For
     example, write `SCHEMA_NAME.PI()' or `SCHEMA_NAME.PI ()'.

   * Alternatively, rename the stored function to use a non-conflicting
     name and change invocations of the function to use the new name.

*Function Name Resolution*

The following rules describe how the server resolves references to
function names for function creation and invocation:

   * Built-in functions and user-defined functions

     As of MySQL 5.1.14, an error occurs if you try to create a UDF
     with the same name as a built-in function. Before 5.1.14, a UDF
     can be created with the same name as a built-in function but the
     UDF cannot be invoked because the parser resolves invocations of
     the function to refer to the built-in function. For example, if
     you create a UDF named `ABS', references to `ABS()' invoke the
     built-in function.

   * Built-in functions and stored functions

     It is possible to create a stored function with the same name as a
     built-in function, but to invoke the stored function it is
     necessary to qualify it with a schema name.  For example, if you
     create a stored function named `PI' in the `test' schema, you
     invoke it as `test.PI()' because the server resolves `PI()' as a
     reference to the built-in function. As of 5.1.14, the server
     creates a warning if the stored function name collides with a
     built-in function name. The warning can be displayed with `SHOW
     WARNINGS'.

   * User-defined functions and stored functions

     User-defined functions and stored functions share the same
     namespace, so you cannot create a UDF and a stored function with
     the same name.

The preceding function name resolution rules have implications for
upgrading to versions of MySQL that implement new built-in functions:

   * If you have already created a user-defined function with a given
     name and upgrade MySQL to a version that implements a new built-in
     function with the same name, the UDF becomes inaccessible. To
     correct this, use `DROP FUNCTION' to drop the UDF, and then use
     `CREATE FUNCTION' to re-create the UDF with a different
     non-conflicting name.

   * If a new version of MySQL implements a built-in function with the
     same name as an existing stored function, you have two choices:
     Rename the stored function to use a non-conflicting name, or
     change calls to the function so that they use a schema qualifier
     (that is, use `SCHEMA_NAME.FUNC_NAME()' syntax).


File: manual.info,  Node: reserved-words,  Next: user-variables,  Prev: identifiers,  Up: language-structure

8.3 Reserved Words
==================

Certain words such as `SELECT', `DELETE', or `BIGINT' are reserved and
require special treatment for use as identifiers such as table and
column names. This may also be true for the names of built-in functions.

Reserved words are permitted as identifiers if you quote them as
described in *Note identifiers:::

     mysql> CREATE TABLE interval (begin INT, end INT);
     ERROR 1064 (42000): You have an error in your SQL syntax ...
     near 'interval (begin INT, end INT)'

     mysql> CREATE TABLE `interval` (begin INT, end INT);
     Query OK, 0 rows affected (0.01 sec)

Exception: A word that follows a period in a qualified name must be an
identifier, so it need not be quoted even if it is reserved:

     mysql> CREATE TABLE mydb.interval (begin INT, end INT);
     Query OK, 0 rows affected (0.01 sec)

Names of built-in functions are permitted as identifiers but may
require care to be used as such. For example, `COUNT' is acceptable as
a column name. However, by default, no whitespace is allowed in
function invocations between the function name and the following ``(''
character. This requirement enables the parser to distinguish whether
the name is used in a function call or in non-function context. For
further detail on recognition of function names, see *Note
function-resolution::.

The words in the following table are explicitly reserved in MySQL 5.1.
At some point, you might upgrade to a higher version, so it's a good
idea to have a look at future reserved words, too. You can find these
in the manuals that cover higher versions of MySQL. Most of the words
in the table are forbidden by standard SQL as column or table names
(for example, `GROUP'). A few are reserved because MySQL needs them and
uses a `yacc' parser. A reserved word can be used as an identifier if
you quote it.

For a more detailed list of reserved words, including differences
between versions, see Reserved Words in MySQL 5.1
(http://dev.mysql.com/doc/mysqld-version-reference/en/mysqld-version-reference-reservedwords-5-1.html).

`ACCESSIBLE'             `ADD'                    `ALL'
`ALTER'                  `ANALYZE'                `AND'
`AS'                     `ASC'                    `ASENSITIVE'
`BEFORE'                 `BETWEEN'                `BIGINT'
`BINARY'                 `BLOB'                   `BOTH'
`BY'                     `CALL'                   `CASCADE'
`CASE'                   `CHANGE'                 `CHAR'
`CHARACTER'              `CHECK'                  `COLLATE'
`COLUMN'                 `CONDITION'              `CONSTRAINT'
`CONTINUE'               `CONVERT'                `CREATE'
`CROSS'                  `CURRENT_DATE'           `CURRENT_TIME'
`CURRENT_TIMESTAMP'      `CURRENT_USER'           `CURSOR'
`DATABASE'               `DATABASES'              `DAY_HOUR'
`DAY_MICROSECOND'        `DAY_MINUTE'             `DAY_SECOND'
`DEC'                    `DECIMAL'                `DECLARE'
`DEFAULT'                `DELAYED'                `DELETE'
`DESC'                   `DESCRIBE'               `DETERMINISTIC'
`DISTINCT'               `DISTINCTROW'            `DIV'
`DOUBLE'                 `DROP'                   `DUAL'
`EACH'                   `ELSE'                   `ELSEIF'
`ENCLOSED'               `ESCAPED'                `EXISTS'
`EXIT'                   `EXPLAIN'                `FALSE'
`FETCH'                  `FLOAT'                  `FLOAT4'
`FLOAT8'                 `FOR'                    `FORCE'
`FOREIGN'                `FROM'                   `FULLTEXT'
`GRANT'                  `GROUP'                  `HAVING'
`HIGH_PRIORITY'          `HOUR_MICROSECOND'       `HOUR_MINUTE'
`HOUR_SECOND'            `IF'                     `IGNORE'
`IN'                     `INDEX'                  `INFILE'
`INNER'                  `INOUT'                  `INSENSITIVE'
`INSERT'                 `INT'                    `INT1'
`INT2'                   `INT3'                   `INT4'
`INT8'                   `INTEGER'                `INTERVAL'
`INTO'                   `IS'                     `ITERATE'
`JOIN'                   `KEY'                    `KEYS'
`KILL'                   `LEADING'                `LEAVE'
`LEFT'                   `LIKE'                   `LIMIT'
`LINEAR'                 `LINES'                  `LOAD'
`LOCALTIME'              `LOCALTIMESTAMP'         `LOCK'
`LONG'                   `LONGBLOB'               `LONGTEXT'
`LOOP'                   `LOW_PRIORITY'           `MASTER_SSL_VERIFY_SERVER_CERT'
`MATCH'                  `MEDIUMBLOB'             `MEDIUMINT'
`MEDIUMTEXT'             `MIDDLEINT'              `MINUTE_MICROSECOND'
`MINUTE_SECOND'          `MOD'                    `MODIFIES'
`NATURAL'                `NOT'                    `NO_WRITE_TO_BINLOG'
`NULL'                   `NUMERIC'                `ON'
`OPTIMIZE'               `OPTION'                 `OPTIONALLY'
`OR'                     `ORDER'                  `OUT'
`OUTER'                  `OUTFILE'                `PRECISION'
`PRIMARY'                `PROCEDURE'              `PURGE'
`RANGE'                  `READ'                   `READS'
`READ_ONLY'              `READ_WRITE'             `REAL'
`REFERENCES'             `REGEXP'                 `RELEASE'
`RENAME'                 `REPEAT'                 `REPLACE'
`REQUIRE'                `RESTRICT'               `RETURN'
`REVOKE'                 `RIGHT'                  `RLIKE'
`SCHEMA'                 `SCHEMAS'                `SECOND_MICROSECOND'
`SELECT'                 `SENSITIVE'              `SEPARATOR'
`SET'                    `SHOW'                   `SMALLINT'
`SPATIAL'                `SPECIFIC'               `SQL'
`SQLEXCEPTION'           `SQLSTATE'               `SQLWARNING'
`SQL_BIG_RESULT'         `SQL_CALC_FOUND_ROWS'    `SQL_SMALL_RESULT'
`SSL'                    `STARTING'               `STRAIGHT_JOIN'
`TABLE'                  `TERMINATED'             `THEN'
`TINYBLOB'               `TINYINT'                `TINYTEXT'
`TO'                     `TRAILING'               `TRIGGER'
`TRUE'                   `UNDO'                   `UNION'
`UNIQUE'                 `UNLOCK'                 `UNSIGNED'
`UPDATE'                 `USAGE'                  `USE'
`USING'                  `UTC_DATE'               `UTC_TIME'
`UTC_TIMESTAMP'          `VALUES'                 `VARBINARY'
`VARCHAR'                `VARCHARACTER'           `VARYING'
`WHEN'                   `WHERE'                  `WHILE'
`WITH'                   `WRITE'                  `XOR'
`YEAR_MONTH'             `ZEROFILL'               

The following are new reserved words in MySQL 5.1:

`ACCESSIBLE'             `LINEAR'                 `MASTER_SSL_VERIFY_SERVER_CERT'
`RANGE'                  `READ_ONLY'              `READ_WRITE'

MySQL allows some keywords to be used as unquoted identifiers because
many people previously used them. Examples are those in the following
list:

   * `ACTION'

   * `BIT'

   * `DATE'

   * `ENUM'

   * `NO'

   * `TEXT'

   * `TIME'

   * `TIMESTAMP'


File: manual.info,  Node: user-variables,  Next: comments,  Prev: reserved-words,  Up: language-structure

8.4 User-Defined Variables
==========================

You can store a value in a user-defined variable and then refer to it
later. This enables you to pass values from one statement to another.
_User-defined variables are connection-specific_. That is, a user
variable defined by one client cannot be seen or used by other clients.
All variables for a given client connection are automatically freed
when that client exits.

User variables are written as `@VAR_NAME', where the variable name
VAR_NAME may consist of alphanumeric characters from the current
character set, ``.'', ``_'', and ``$''. The default character set is
`latin1' (cp1252 West European). This may be changed with the
`--character-set-server' option to `mysqld'. See *Note
charset-configuration::. A user variable name can contain other
characters if you quote it as a string or identifier (for example,
`@'my-var'', `@"my-var"', or `@`my-var`').

Note: User variable names not case sensitive in MySQL 5.0 and up.

One way to set a user-defined variable is by issuing a `SET' statement:

     SET @VAR_NAME = EXPR [, @VAR_NAME = EXPR] ...

For `SET', either `=' or `:=' can be used as the assignment operator.
The EXPR assigned to each variable can evaluate to an integer, decimal,
floating-point, string, or `NULL' value. However, if the value of the
variable is selected in a result set, it is returned to the client as a
string. Assignment of decimal and real values does not preserve the
precision or scale of the value.

You can also assign a value to a user variable in statements other than
`SET'. In this case, the assignment operator must be `:=' and not `='
because `=' is treated as a comparison operator in non-`SET' statements:

     mysql> SET @t1=0, @t2=0, @t3=0;
     mysql> SELECT @t1:=(@t2:=1)+@t3:=4,@t1,@t2,@t3;
     +----------------------+------+------+------+
     | @t1:=(@t2:=1)+@t3:=4 | @t1  | @t2  | @t3  |
     +----------------------+------+------+------+
     |                    5 |    5 |    1 |    4 |
     +----------------------+------+------+------+

User variables may be used in contexts where expressions are allowed.
This does not currently include contexts that explicitly require a
literal value, such as in the `LIMIT' clause of a `SELECT' statement,
or the `IGNORE N LINES' clause of a `LOAD DATA' statement.

User variables are intended to provide data values. They cannot be used
to supply identifiers, such as in contexts where a table or database
name is expected, or reserved words such as `SELECT'. An exception to
this principle is that if you are constructing a string for use as a
prepared statement to be executed later, user variables can be
referenced to provide any part of the statement.

If a user variable is assigned a string value, it has the same
character set and collation as the string. The coercibility of user
variables is implicit. (This is the same coercibility as for table
column values.)

If you refer to a variable that has not been initialized, it has a
value of `NULL' and a type of string.

Bit values assigned to user variables are treated as binary strings. To
assign a bit value as a number to a user variable, use `CAST()' or `+0':

     mysql> SET @v1 = b'1000001';
     mysql> SET @v2 = CAST(b'1000001' AS UNSIGNED), @v3 = b'1000001'+0;
     mysql> SELECT @v1, @v2, @v3;
     +------+------+------+
     | @v1  | @v2  | @v3  |
     +------+------+------+
     | A    |   65 |   65 |
     +------+------+------+

*Note*:

In a `SELECT' statement, each expression is evaluated only when sent to
the client. This means that in a `HAVING', `GROUP BY', or `ORDER BY'
clause, you cannot refer to an expression that involves variables that
are set in the `SELECT' list. For example, the following statement does
_not_ work as expected:

     mysql> SELECT (@aa:=id) AS a, (@aa+3) AS b FROM TBL_NAME HAVING b=5;

The reference to `b' in the `HAVING' clause refers to an alias for an
expression in the `SELECT' list that uses `@aa'. This does not work as
expected: `@aa' contains the value of `id' from the previous selected
row, not from the current row.

The order of evaluation for user variables is undefined and may change
based on the elements contained within a given query. In `SELECT @a, @a
:= @a+1 ...', you might think that MySQL will evaluate `@a' first and
then do an assignment second, but changing the query (for example, by
adding a `GROUP BY', `HAVING', or `ORDER BY' clause) may change the
order of evaluation.

The general rule is never to assign a value to a user variable in one
part of a statement _and_ use the same variable in some other part of
the same statement. You might get the results you expect, but this is
not guaranteed.

Another issue with setting a variable and using it in the same
statement is that the default result type of a variable is based on the
type of the variable at the start of the statement. The following
example illustrates this:

     mysql> SET @a='test';
     mysql> SELECT @a,(@a:=20) FROM TBL_NAME;

For this `SELECT' statement, MySQL reports to the client that column
one is a string and converts all accesses of `@a' to strings, even
though @a is set to a number for the second row. After the `SELECT'
statement executes, `@a' is regarded as a number for the next statement.

To avoid problems with this behavior, either do not set and use the
same variable within a single statement, or else set the variable to
`0', `0.0', or `''' to define its type before you use it.

A user variable cannot be used directly in an SQL statement as an
identifier or as part of an identifier, even if it is set off with
backticks. This is shown in the following example:

     mysql> SELECT c1 FROM t;
     +----+
     | c1 |
     +----+
     |  0 |
     +----+
     |  1 |
     +----+
     2 rows in set (0.00 sec)

     mysql> SET @col = "c1";
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT @col FROM t;
     +------+
     | @col |
     +------+
     | c1   |
     +------+
     1 row in set (0.00 sec)

     mysql> SELECT `@col` FROM t;
     `ERROR 1054 (42S22): Unknown column '@col' in 'field list''

     mysql> SET @col = "`c1`";
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT @col FROM t;
     +------+
     | @col |
     +------+
     | `c1` |
     +------+
     1 row in set (0.00 sec)

One way to work around this problem is to assemble a string for the
query in application code, as shown here using PHP 5:

     <?php
       $mysqli = new mysqli("localhost", "user", "pass", "test");

       if( mysqli_connect_errno() )
         die("Connection failed: %s\n", mysqli_connect_error());

       $col = "c1";

       $query = "SELECT $col FROM t";

       $result = $mysqli->query($query);

       while($row = $result->fetch_assoc())
       {
         echo "<p>" . $row["$col"] . "</p>\n";
       }

       $result->close();

       $mysqli->close();
     ?>

(Assembling an SQL statement in this fashion is sometimes known as
`Dynamic SQL'.) It is also possible to perform such operations using
prepared statements, without the need to concatenate strings of SQL in
client code. This example illustrates how this can be done:

     mysql> SET @c = "c1";
     Query OK, 0 rows affected (0.00 sec)

     mysql> SET @s = CONCAT("SELECT ", @c, " FROM t");
     Query OK, 0 rows affected (0.00 sec)

     mysql> PREPARE stmt FROM @s;
     Query OK, 0 rows affected (0.04 sec)
     Statement prepared

     mysql> EXECUTE stmt;
     +----+
     | c1 |
     +----+
     |  0 |
     +----+
     |  1 |
     +----+
     2 rows in set (0.00 sec)

     mysql> DEALLOCATE PREPARE stmt;
     Query OK, 0 rows affected (0.00 sec)

You cannot use a placeholder for an identifier (such as the name of a
database, table, or column) in an SQL prepared statement. See *Note
sql-syntax-prepared-statements::, for more information.


File: manual.info,  Node: comments,  Prev: user-variables,  Up: language-structure

8.5 Comment Syntax
==================

MySQL Server supports three comment styles:

   * From a ``#'' character to the end of the line.

   * From a ``-- '' sequence to the end of the line. In MySQL, the ``--
     '' (double-dash) comment style requires the second dash to be
     followed by at least one whitespace or control character (such as
     a space, tab, newline, and so on). This syntax differs slightly
     from standard SQL comment syntax, as discussed in *Note
     ansi-diff-comments::.

   * From a `/*' sequence to the following `*/' sequence, as in the C
     programming language. This syntax allows a comment to extend over
     multiple lines because the beginning and closing sequences need
     not be on the same line.

The following example demonstrates all three comment styles:

     mysql> SELECT 1+1;     # This comment continues to the end of line
     mysql> SELECT 1+1;     -- This comment continues to the end of line
     mysql> SELECT 1 /* this is an in-line comment */ + 1;
     mysql> SELECT 1+
     /*
     this is a
     multiple-line comment
     */
     1;

Nested comments are not supported.

MySQL Server supports some variants of C-style comments. These enable
you to write code that includes MySQL extensions, but is still
portable, by using comments of the following form:

     /*! MYSQL-SPECIFIC CODE */

In this case, MySQL Server parses and executes the code within the
comment as it would any other SQL statement, but other SQL servers will
ignore the extensions. For example, MySQL Server recognizes the
`STRAIGHT_JOIN' keyword in the following statement, but other servers
will not:

     SELECT /*! STRAIGHT_JOIN */ col1 FROM table1,table2 WHERE ...

If you add a version number after the ``!'' character, the syntax within
the comment is executed only if the MySQL version is greater than or
equal to the specified version number. The `TEMPORARY' keyword in the
following comment is executed only by servers from MySQL 3.23.02 or
higher:

     CREATE /*!32302 TEMPORARY */ TABLE t (a INT);

The comment syntax just described applies to how the `mysqld' server
parses SQL statements. The `mysql' client program also performs some
parsing of statements before sending them to the server. (It does this
to determine statement boundaries within a multiple-statement input
line.)

The use of short-form `mysql' commands such as `\C' within multi-line
`/* ...  */' comments is not supported.


File: manual.info,  Node: internationalization-localization,  Next: data-types,  Prev: language-structure,  Up: Top

9 Internationalization and Localization
***************************************

* Menu:

* charset::                      Character Set Support
* charset-configuration::        The Character Set Used for Data and Sorting
* error-message-language::       Setting the Error Message Language
* adding-character-set::         Adding a New Character Set
* adding-collation::             How to Add a New Collation to a Character Set
* problems-with-character-sets::  Problems With Character Sets
* time-zone-support::            MySQL Server Time Zone Support
* locale-support::               MySQL Server Locale Support

This chapter covers issues of internationalization (MySQL's
capabilities for adapting to local use) and localization (selecting
particular local conventions):

   * MySQL support for character sets in SQL statements.

   * How to configure the server to support different character sets.

   * Selecting the language for error messages.

   * How to set the server's time zone and enable per-connection time
     zone support.

   * Selecting the locale for day and month names.


File: manual.info,  Node: charset,  Next: charset-configuration,  Prev: internationalization-localization,  Up: internationalization-localization

9.1 Character Set Support
=========================

* Menu:

* charset-general::              Character Sets and Collations in General
* charset-mysql::                Character Sets and Collations in MySQL
* charset-syntax::               Specifying Character Sets and Collations
* charset-connection::           Connection Character Sets and Collations
* charset-collations::           Collation Issues
* charset-repertoire::           String Repertoire
* charset-operations::           Operations Affected by Character Set Support
* charset-unicode::              Unicode Support
* charset-metadata::             UTF-8 for Metadata
* charset-conversion::           Column Character Set Conversion
* charset-charsets::             Character Sets and Collations That MySQL Supports

MySQL includes character set support that enables you to store data
using a variety of character sets and perform comparisons according to
a variety of collations. You can specify character sets at the server,
database, table, and column level. MySQL supports the use of character
sets for the `MyISAM', `MEMORY', `NDBCLUSTER', and `InnoDB' storage
engines.

This chapter discusses the following topics:

   * What are character sets and collations?

   * The multiple-level default system for character set assignment

   * Syntax for specifying character sets and collations

   * Affected functions and operations

   * Unicode support

   * The character sets and collations that are available, with notes

Character set issues affect not only data storage, but also
communication between client programs and the MySQL server. If you want
the client program to communicate with the server using a character set
different from the default, you'll need to indicate which one. For
example, to use the `utf8' Unicode character set, issue this statement
after connecting to the server:

     SET NAMES 'utf8';

For more information about character set-related issues in
client/server communication, see *Note charset-connection::.


File: manual.info,  Node: charset-general,  Next: charset-mysql,  Prev: charset,  Up: charset

9.1.1 Character Sets and Collations in General
----------------------------------------------

A _character set_ is a set of symbols and encodings. A _collation_ is a
set of rules for comparing characters in a character set. Let's make the
distinction clear with an example of an imaginary character set.

Suppose that we have an alphabet with four letters: ``A'', ``B'', ``a'',
``b''. We give each letter a number: ``A'' = 0, ``B'' = 1, ``a'' = 2,
``b'' = 3. The letter ``A'' is a symbol, the number 0 is the *encoding*
for ``A'', and the combination of all four letters and their encodings
is a *character set*.

Suppose that we want to compare two string values, ``A'' and ``B''. The
simplest way to do this is to look at the encodings: 0 for ``A'' and 1
for ``B''. Because 0 is less than 1, we say ``A'' is less than ``B''.
What we've just done is apply a collation to our character set. The
collation is a set of rules (only one rule in this case): `compare the
encodings.' We call this simplest of all possible collations a _binary_
collation.

But what if we want to say that the lowercase and uppercase letters are
equivalent? Then we would have at least two rules: (1) treat the
lowercase letters ``a'' and ``b'' as equivalent to ``A'' and ``B''; (2)
then compare the encodings. We call this a _case-insensitive_
collation. It's a little more complex than a binary collation.

In real life, most character sets have many characters: not just ``A''
and ``B'' but whole alphabets, sometimes multiple alphabets or eastern
writing systems with thousands of characters, along with many special
symbols and punctuation marks. Also in real life, most collations have
many rules, not just for whether to distinguish lettercase, but also
for whether to distinguish accents (an `accent' is a mark attached to a
character as in German ``O"''), and for multiple-character mappings
(such as the rule that ``O"'' = ``OE'' in one of the two German
collations).

MySQL can do these things for you:

   * Store strings using a variety of character sets

   * Compare strings using a variety of collations

   * Mix strings with different character sets or collations in the
     same server, the same database, or even the same table

   * Allow specification of character set and collation at any level

In these respects, MySQL is far ahead of most other database management
systems. However, to use these features effectively, you need to know
what character sets and collations are available, how to change the
defaults, and how they affect the behavior of string operators and
functions.


File: manual.info,  Node: charset-mysql,  Next: charset-syntax,  Prev: charset-general,  Up: charset

9.1.2 Character Sets and Collations in MySQL
--------------------------------------------

The MySQL server can support multiple character sets. To list the
available character sets, use the `SHOW CHARACTER SET' statement. A
partial listing follows. For more complete information, see *Note
charset-charsets::.

     mysql> SHOW CHARACTER SET;
     +----------+-----------------------------+---------------------+--------+
     | Charset  | Description                 | Default collation   | Maxlen |
     +----------+-----------------------------+---------------------+--------+
     | big5     | Big5 Traditional Chinese    | big5_chinese_ci     |      2 |
     | dec8     | DEC West European           | dec8_swedish_ci     |      1 |
     | cp850    | DOS West European           | cp850_general_ci    |      1 |
     | hp8      | HP West European            | hp8_english_ci      |      1 |
     | koi8r    | KOI8-R Relcom Russian       | koi8r_general_ci    |      1 |
     | latin1   | cp1252 West European        | latin1_swedish_ci   |      1 |
     | latin2   | ISO 8859-2 Central European | latin2_general_ci   |      1 |
     | swe7     | 7bit Swedish                | swe7_swedish_ci     |      1 |
     | ascii    | US ASCII                    | ascii_general_ci    |      1 |
     | ujis     | EUC-JP Japanese             | ujis_japanese_ci    |      3 |
     | sjis     | Shift-JIS Japanese          | sjis_japanese_ci    |      2 |
     | hebrew   | ISO 8859-8 Hebrew           | hebrew_general_ci   |      1 |
     | tis620   | TIS620 Thai                 | tis620_thai_ci      |      1 |
     | euckr    | EUC-KR Korean               | euckr_korean_ci     |      2 |
     | koi8u    | KOI8-U Ukrainian            | koi8u_general_ci    |      1 |
     | gb2312   | GB2312 Simplified Chinese   | gb2312_chinese_ci   |      2 |
     | greek    | ISO 8859-7 Greek            | greek_general_ci    |      1 |
     | cp1250   | Windows Central European    | cp1250_general_ci   |      1 |
     | gbk      | GBK Simplified Chinese      | gbk_chinese_ci      |      2 |
     | latin5   | ISO 8859-9 Turkish          | latin5_turkish_ci   |      1 |
     ...

Any given character set always has at least one collation. It may have
several collations. To list the collations for a character set, use the
`SHOW COLLATION' statement. For example, to see the collations for the
`latin1' (cp1252 West European) character set, use this statement to
find those collation names that begin with `latin1':

     mysql> SHOW COLLATION LIKE 'latin1%';
     +---------------------+---------+----+---------+----------+---------+
     | Collation           | Charset | Id | Default | Compiled | Sortlen |
     +---------------------+---------+----+---------+----------+---------+
     | latin1_german1_ci   | latin1  |  5 |         |          |       0 |
     | latin1_swedish_ci   | latin1  |  8 | Yes     | Yes      |       1 |
     | latin1_danish_ci    | latin1  | 15 |         |          |       0 |
     | latin1_german2_ci   | latin1  | 31 |         | Yes      |       2 |
     | latin1_bin          | latin1  | 47 |         | Yes      |       1 |
     | latin1_general_ci   | latin1  | 48 |         |          |       0 |
     | latin1_general_cs   | latin1  | 49 |         |          |       0 |
     | latin1_spanish_ci   | latin1  | 94 |         |          |       0 |
     +---------------------+---------+----+---------+----------+---------+

The `latin1' collations have the following meanings:

*Collation*                   *Meaning*
`latin1_german1_ci'           German DIN-1
`latin1_swedish_ci'           Swedish/Finnish
`latin1_danish_ci'            Danish/Norwegian
`latin1_german2_ci'           German DIN-2
`latin1_bin'                  Binary according to `latin1' encoding
`latin1_general_ci'           Multilingual (Western European)
`latin1_general_cs'           Multilingual (ISO Western European), case
                              sensitive
`latin1_spanish_ci'           Modern Spanish

Collations have these general characteristics:

   * Two different character sets cannot have the same collation.

   * Each character set has one collation that is the _default
     collation_. For example, the default collation for `latin1' is
     `latin1_swedish_ci'. The output for `SHOW CHARACTER SET' indicates
     which collation is the default for each displayed character set.

   * There is a convention for collation names: They start with the
     name of the character set with which they are associated, they
     usually include a language name, and they end with `_ci' (case
     insensitive), `_cs' (case sensitive), or `_bin' (binary).

In cases where a character set has multiple collations, it might not be
clear which collation is most suitable for a given application. To
avoid choosing the wrong collation, it can be helpful to perform some
comparisons with representative data values to make sure that a given
collation sorts values the way you expect.

Collation-Charts.Org (http://www.collation-charts.org/) is a useful
site for information that shows how one collation compares to another.


File: manual.info,  Node: charset-syntax,  Next: charset-connection,  Prev: charset-mysql,  Up: charset

9.1.3 Specifying Character Sets and Collations
----------------------------------------------

* Menu:

* charset-server::               Server Character Set and Collation
* charset-database::             Database Character Set and Collation
* charset-table::                Table Character Set and Collation
* charset-column::               Column Character Set and Collation
* charset-literal::              Character String Literal Character Set and Collation
* charset-national::             National Character Set
* charset-examples::             Examples of Character Set and Collation Assignment
* charset-compatibility::        Compatibility with Other DBMSs

There are default settings for character sets and collations at four
levels: server, database, table, and column. The description in the
following sections may appear complex, but it has been found in
practice that multiple-level defaulting leads to natural and obvious
results.

`CHARACTER SET' is used in clauses that specify a character set.
`CHARSET' may be used as a synonym for `CHARACTER SET'.

Character set issues affect not only data storage, but also
communication between client programs and the MySQL server. If you want
the client program to communicate with the server using a character set
different from the default, you'll need to indicate which one. For
example, to use the `utf8' Unicode character set, issue this statement
after connecting to the server:

     SET NAMES 'utf8';

For more information about character set-related issues in
client/server communication, see *Note charset-connection::.


File: manual.info,  Node: charset-server,  Next: charset-database,  Prev: charset-syntax,  Up: charset-syntax

9.1.3.1 Server Character Set and Collation
..........................................

MySQL Server has a server character set and a server collation. These
can be set at server startup on the command line or in an option file
and changed at runtime.

Initially, the server character set and collation depend on the options
that you use when you start `mysqld'. You can use
`--character-set-server' for the character set.  Along with it, you can
add `--collation-server' for the collation. If you don't specify a
character set, that is the same as saying
`--character-set-server=latin1'. If you specify only a character set
(for example, `latin1') but not a collation, that is the same as saying
`--character-set-server=latin1' `--collation-server=latin1_swedish_ci'
because `latin1_swedish_ci' is the default collation for `latin1'.
Therefore, the following three commands all have the same effect:

     shell> mysqld
     shell> mysqld --character-set-server=latin1
     shell> mysqld --character-set-server=latin1 \
                --collation-server=latin1_swedish_ci

One way to change the settings is by recompiling. If you want to change
the default server character set and collation when building from
sources, use: `--with-charset' and `--with-collation' as arguments for
`configure'. For example:

     shell> ./configure --with-charset=latin1

Or:

     shell> ./configure --with-charset=latin1 \
                --with-collation=latin1_german1_ci

Both `mysqld' and `configure' verify that the character set/collation
combination is valid. If not, each program displays an error message
and terminates.

The server character set and collation are used as default values if
the database character set and collation are not specified in `CREATE
DATABASE' statements.  They have no other purpose.

The current server character set and collation can be determined from
the values of the `character_set_server' and `collation_server' system
variables. These variables can be changed at runtime.


File: manual.info,  Node: charset-database,  Next: charset-table,  Prev: charset-server,  Up: charset-syntax

9.1.3.2 Database Character Set and Collation
............................................

Every database has a database character set and a database collation.
The `CREATE DATABASE' and `ALTER DATABASE' statements have optional
clauses for specifying the database character set and collation:

     CREATE DATABASE DB_NAME
         [[DEFAULT] CHARACTER SET CHARSET_NAME]
         [[DEFAULT] COLLATE COLLATION_NAME]

     ALTER DATABASE DB_NAME
         [[DEFAULT] CHARACTER SET CHARSET_NAME]
         [[DEFAULT] COLLATE COLLATION_NAME]

The keyword `SCHEMA' can be used instead of `DATABASE'.

All database options are stored in a text file named `db.opt' that can
be found in the database directory.

The `CHARACTER SET' and `COLLATE' clauses make it possible to create
databases with different character sets and collations on the same
MySQL server.

Example:

     CREATE DATABASE DB_NAME CHARACTER SET latin1 COLLATE latin1_swedish_ci;

MySQL chooses the database character set and database collation in the
following manner:

   * If both `CHARACTER SET X' and `COLLATE Y' were specified, then
     character set X and collation Y.

   * If `CHARACTER SET X' was specified without `COLLATE', then
     character set X and its default collation.

   * If `COLLATE Y' was specified without `CHARACTER SET', then the
     character set associated with Y and collation Y.

   * Otherwise, the server character set and server collation.

The database character set and collation are used as default values if
the table character set and collation are not specified in `CREATE
TABLE' statements. The database character set also is used by `LOAD DATA
INFILE'. The character set and collation have no other purposes.

The character set and collation for the default database can be
determined from the values of the `character_set_database' and
`collation_database' system variables. The server sets these variables
whenever the default database changes. If there is no default database,
the variables have the same value as the corresponding server-level
system variables, `character_set_server' and `collation_server'.


File: manual.info,  Node: charset-table,  Next: charset-column,  Prev: charset-database,  Up: charset-syntax

9.1.3.3 Table Character Set and Collation
.........................................

Every table has a table character set and a table collation.  The
`CREATE TABLE' and `ALTER TABLE' statements have optional clauses for
specifying the table character set and collation:

     CREATE TABLE TBL_NAME (COLUMN_LIST)
         [[DEFAULT] CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]]

     ALTER TABLE TBL_NAME
         [[DEFAULT] CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]

Example:

     CREATE TABLE t1 ( ... ) CHARACTER SET latin1 COLLATE latin1_danish_ci;

MySQL chooses the table character set and collation in the following
manner:

   * If both `CHARACTER SET X' and `COLLATE Y' were specified, then
     character set X and collation Y.

   * If `CHARACTER SET X' was specified without `COLLATE', then
     character set X and its default collation.

   * If `COLLATE Y' was specified without `CHARACTER SET', then the
     character set associated with Y and collation Y.

   * Otherwise, the database character set and collation.

The table character set and collation are used as default values if the
column character set and collation are not specified in individual
column definitions. The table character set and collation are MySQL
extensions; there are no such things in standard SQL.


File: manual.info,  Node: charset-column,  Next: charset-literal,  Prev: charset-table,  Up: charset-syntax

9.1.3.4 Column Character Set and Collation
..........................................

Every `character' column (that is, a column of type `CHAR', `VARCHAR',
or `TEXT') has a column character set and a column collation. Column
definition syntax for `CREATE TABLE' and `ALTER TABLE' has optional
clauses for specifying the column character set and collation:

     COL_NAME {CHAR | VARCHAR | TEXT} (COL_LENGTH)
         [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]

Examples:

     CREATE TABLE Table1
     (
         column1 VARCHAR(5) CHARACTER SET latin1 COLLATE latin1_german1_ci
     );

     ALTER TABLE Table1 MODIFY
         column1 VARCHAR(5) CHARACTER SET latin1 COLLATE latin1_swedish_ci;

If you convert a column from one character set to another, `ALTER
TABLE' attempts to map the data values, but if the character sets are
incompatible, there may be data loss.

MySQL chooses the column character set and collation in the following
manner:

   * If both `CHARACTER SET X' and `COLLATE Y' were specified, then
     character set X and collation Y are used.

   * If `CHARACTER SET X' was specified without `COLLATE', then
     character set X and its default collation are used.

   * If `COLLATE Y' was specified without `CHARACTER SET', then the
     character set associated with Y and collation Y.

   * Otherwise, the table character set and collation are used.

The `CHARACTER SET' and `COLLATE' clauses are standard SQL.


File: manual.info,  Node: charset-literal,  Next: charset-national,  Prev: charset-column,  Up: charset-syntax

9.1.3.5 Character String Literal Character Set and Collation
............................................................

Every character string literal has a character set and a collation.

A character string literal may have an optional character set
introducer and `COLLATE' clause:

     [_CHARSET_NAME]'STRING' [COLLATE COLLATION_NAME]

Examples:

     SELECT 'STRING';
     SELECT _latin1'STRING';
     SELECT _latin1'STRING' COLLATE latin1_danish_ci;

For the simple statement `SELECT 'STRING'', the string has the
character set and collation defined by the `character_set_connection'
and `collation_connection' system variables.

The `_CHARSET_NAME' expression is formally called an _introducer_. It
tells the parser, `the string that is about to follow uses character set
X.' Because this has confused people in the past, we emphasize that an
introducer does not change the string to the introducer character set
like `CONVERT()' would do. It does not change the string's value,
although padding may occur. The introducer is just a signal. An
introducer is also legal before standard hex literal and numeric hex
literal notation (`x'LITERAL'' and `0xNNNN').

Examples:

     SELECT _latin1 x'AABBCC';
     SELECT _latin1 0xAABBCC;

MySQL determines a literal's character set and collation in the
following manner:

   * If both _X and `COLLATE Y' were specified, then character set X and
     collation Y are used.

   * If _X is specified but `COLLATE' is not specified, then character
     set X and its default collation are used.

   * Otherwise, the character set and collation given by the
     `character_set_connection' and `collation_connection' system
     variables are used.

Examples:

   * A string with `latin1' character set and `latin1_german1_ci'
     collation:

          SELECT _latin1'Mu"ller' COLLATE latin1_german1_ci;

   * A string with `latin1' character set and its default collation
     (that is, `latin1_swedish_ci'):

          SELECT _latin1'Mu"ller';

   * A string with the connection default character set and collation:

          SELECT 'Mu"ller';

Character set introducers and the `COLLATE' clause are implemented
according to standard SQL specifications.

An introducer indicates the character set for the following string, but
does not change now how the parser performs escape processing within
the string. Escapes are always interpreted by the parser according to
the character set given by `character_set_connection'.

The following examples show that escape processing occurs using
`character_set_connection' even in the presence of an introducer. The
examples use `SET NAMES' (which changes `character_set_connection', as
discussed in *Note charset-connection::), and display the resulting
strings using the `HEX()' function so that the exact string contents
can be seen.

Example 1:

     mysql> SET NAMES latin1;
     Query OK, 0 rows affected (0.01 sec)

     mysql> SELECT HEX('a`\n'), HEX(_sjis'a`\n');
     +------------+-----------------+
     | HEX('a`\n') | HEX(_sjis'a`\n') |
     +------------+-----------------+
     | E00A       | E00A            |
     +------------+-----------------+
     1 row in set (0.00 sec)

Here, ``a`'' (hex value `E0') is followed by ``\n'', the escape
sequence for newline. The escape sequence is interpreted using the
`character_set_connection' value of `latin1' to produce a literal
newline (hex value `0A'). This happens even for the second string. That
is, the introducer of `_sjis' does not affect the parser's escape
processing.

Example 2:

     mysql> SET NAMES sjis;
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT HEX('a`\n'), HEX(_latin1'a`\n');
     +------------+-------------------+
     | HEX('a`\n') | HEX(_latin1'a`\n') |
     +------------+-------------------+
     | E05C6E     | E05C6E            |
     +------------+-------------------+
     1 row in set (0.04 sec)

Here, `character_set_connection' is `sjis', a character set in which
the sequence of ``a`'' followed by ``\'' (hex values `05' and `5C') is
a valid multi-byte character. Hence, the first two bytes of the string
are interpreted as a single `sjis' character, and the ``\'' is not
intrepreted as an escape character. The following ``n'' (hex value
`6E') is not interpreted as part of an escape sequence. This is true
even for the second string; the introducer of `_latin1' does not affect
escape processing.


File: manual.info,  Node: charset-national,  Next: charset-examples,  Prev: charset-literal,  Up: charset-syntax

9.1.3.6 National Character Set
..............................

Standard SQL defines `NCHAR' or `NATIONAL CHAR' as a way to indicate
that a `CHAR' column should use some predefined character set. MySQL
5.1 uses `utf8' as this predefined character set. For example, these
data type declarations are equivalent:

     CHAR(10) CHARACTER SET utf8
     NATIONAL CHARACTER(10)
     NCHAR(10)

As are these:

     VARCHAR(10) CHARACTER SET utf8
     NATIONAL VARCHAR(10)
     NCHAR VARCHAR(10)
     NATIONAL CHARACTER VARYING(10)
     NATIONAL CHAR VARYING(10)

You can use `N'LITERAL'' (or `n'LITERAL'') to create a string in the
national character set. These statements are equivalent:

     SELECT N'some text';
     SELECT n'some text';
     SELECT _utf8'some text';

For information on upgrading character sets to MySQL 5.1 from versions
prior to 4.1, see the `MySQL 3.23, 4.0, 4.1 Reference Manual'.


File: manual.info,  Node: charset-examples,  Next: charset-compatibility,  Prev: charset-national,  Up: charset-syntax

9.1.3.7 Examples of Character Set and Collation Assignment
..........................................................

The following examples show how MySQL determines default character set
and collation values.

*Example 1: Table and Column Definition*

     CREATE TABLE t1
     (
         c1 CHAR(10) CHARACTER SET latin1 COLLATE latin1_german1_ci
     ) DEFAULT CHARACTER SET latin2 COLLATE latin2_bin;

Here we have a column with a `latin1' character set and a
`latin1_german1_ci' collation. The definition is explicit, so that's
straightforward. Notice that there is no problem with storing a
`latin1' column in a `latin2' table.

*Example 2: Table and Column Definition*

     CREATE TABLE t1
     (
         c1 CHAR(10) CHARACTER SET latin1
     ) DEFAULT CHARACTER SET latin1 COLLATE latin1_danish_ci;

This time we have a column with a `latin1' character set and a default
collation. Although it might seem natural, the default collation is not
taken from the table level. Instead, because the default collation for
`latin1' is always `latin1_swedish_ci', column `c1' has a collation of
`latin1_swedish_ci' (not `latin1_danish_ci').

*Example 3: Table and Column Definition*

     CREATE TABLE t1
     (
         c1 CHAR(10)
     ) DEFAULT CHARACTER SET latin1 COLLATE latin1_danish_ci;

We have a column with a default character set and a default collation.
In this circumstance, MySQL checks the table level to determine the
column character set and collation.  Consequently, the character set
for column `c1' is `latin1' and its collation is `latin1_danish_ci'.

*Example 4: Database, Table, and Column Definition*

     CREATE DATABASE d1
         DEFAULT CHARACTER SET latin2 COLLATE latin2_czech_ci;
     USE d1;
     CREATE TABLE t1
     (
         c1 CHAR(10)
     );

We create a column without specifying its character set and collation.
We're also not specifying a character set and a collation at the table
level. In this circumstance, MySQL checks the database level to
determine the table settings, which thereafter become the column
settings.) Consequently, the character set for column `c1' is `latin2'
and its collation is `latin2_czech_ci'.


File: manual.info,  Node: charset-compatibility,  Prev: charset-examples,  Up: charset-syntax

9.1.3.8 Compatibility with Other DBMSs
......................................

For MaxDB compatibility these two statements are the same:

     CREATE TABLE t1 (f1 CHAR(N) UNICODE);
     CREATE TABLE t1 (f1 CHAR(N) CHARACTER SET ucs2);


File: manual.info,  Node: charset-connection,  Next: charset-collations,  Prev: charset-syntax,  Up: charset

9.1.4 Connection Character Sets and Collations
----------------------------------------------

Several character set and collation system variables relate to a
client's interaction with the server. Some of these have been mentioned
in earlier sections:

   * The server character set and collation can be determined from the
     values of the `character_set_server' and `collation_server' system
     variables.

   * The character set and collation of the default database can be
     determined from the values of the `character_set_database' and
     `collation_database' system variables.

Additional character set and collation system variables are involved in
handling traffic for the connection between a client and the server.
Every client has connection-related character set and collation system
variables.

Consider what a `connection' is: It's what you make when you connect to
the server. The client sends SQL statements, such as queries, over the
connection to the server. The server sends responses, such as result
sets, over the connection back to the client. This leads to several
questions about character set and collation handling for client
connections, each of which can be answered in terms of system variables:

   * What character set is the statement in when it leaves the client?

     The server takes the `character_set_client' system variable to be
     the character set in which statements are sent by the client.

   * What character set should the server translate a statement to
     after receiving it?

     For this, the server uses the `character_set_connection' and
     `collation_connection' system variables. It converts statements
     sent by the client from `character_set_client' to
     `character_set_connection' (except for string literals that have
     an introducer such as `_latin1' or `_utf8').
     `collation_connection' is important for comparisons of literal
     strings. For comparisons of strings with column values,
     `collation_connection' does not matter because columns have their
     own collation, which has a higher collation precedence.

   * What character set should the server translate to before shipping
     result sets or error messages back to the client?

     The `character_set_results' system variable indicates the
     character set in which the server returns query results to the
     client. This includes result data such as column values, and
     result metadata such as column names.

You can fine-tune the settings for these variables, or you can depend
on the defaults (in which case, you can skip the rest of this section).

There are two statements that affect the connection character sets:

     SET NAMES 'CHARSET_NAME'
     SET CHARACTER SET CHARSET_NAME

`SET NAMES' indicates what character set the client will use to send
SQL statements to the server. Thus, `SET NAMES 'cp1251'' tells the
server `future incoming messages from this client are in character set
`cp1251'.' It also specifies the character set that the server should
use for sending results back to the client. (For example, it indicates
what character set to use for column values if you use a `SELECT'
statement.)

A `SET NAMES 'X'' statement is equivalent to these three statements:

     SET character_set_client = X;
     SET character_set_results = X;
     SET character_set_connection = X;

Setting `character_set_connection' to X also sets
`collation_connection' to the default collation for X. It is not
necessary to set that collation explicitly. To specify a particular
collation for the character sets, use the optional `COLLATE' clause:

     SET NAMES 'CHARSET_NAME' COLLATE 'COLLATION_NAME'

`SET CHARACTER SET' is similar to `SET NAMES' but sets
`character_set_connection' and `collation_connection' to
`character_set_database' and `collation_database'. A `SET CHARACTER SET
X' statement is equivalent to these three statements:

     SET character_set_client = X;
     SET character_set_results = X;
     SET collation_connection = @@collation_database;

Setting `collation_connection' also sets `character_set_connection' to
the character set associated with the collation (equivalent to executing
`SET character_set_connection = @@character_set_database'). It is not
necessary to set `character_set_connection' explicitly.

When a client connects, it sends to the server the name of the
character set that it wants to use. The server uses the name to set the
`character_set_client', `character_set_results', and
`character_set_connection' system variables. In effect, the server
performs a `SET NAMES' operation using the character set name.

With the `mysql' client, it is not necessary to execute `SET NAMES'
every time you start up if you want to use a character set different
from the default. You can add the `--default-character-set' option
setting to your `mysql' statement line, or in your option file. For
example, the following option file setting changes the three character
set variables set to `koi8r' each time you invoke `mysql':

     [mysql]
     default-character-set=koi8r

If you are using the `mysql' client with auto-reconnect enabled (which
is not recommended), it is preferable to use the `charset' command
rather than `SET NAMES'. For example:

     mysql> charset utf8
     Charset changed

The `charset' command issues a `SET NAMES' statement, and also changes
the default character set that is used if `mysql' reconnects after the
connection has dropped.

Example: Suppose that `column1' is defined as `CHAR(5) CHARACTER SET
latin2'. If you do not say `SET NAMES' or `SET CHARACTER SET', then for
`SELECT column1 FROM t', the server sends back all the values for
`column1' using the character set that the client specified when it
connected. On the other hand, if you say `SET NAMES 'latin1'' or `SET
CHARACTER SET latin1' before issuing the `SELECT' statement, the server
converts the `latin2' values to `latin1' just before sending results
back. Conversion may be lossy if there are characters that are not in
both character sets.

If you do not want the server to perform any conversion of result sets,
set `character_set_results' to `NULL':

     SET character_set_results = NULL;

*Note*:

`ucs2' cannot be used as a client character set, which means that it
does not work for `SET NAMES' or `SET CHARACTER SET'.

To see the values of the character set and collation system variables
that apply to your connection, use these statements:

     SHOW VARIABLES LIKE 'character_set%';
     SHOW VARIABLES LIKE 'collation%';

You must also consider the environment within which your MySQL
application executes. For example, if you will send statements using
UTF-8 text taken from a file that you create in an editor, you should
edit the file with the locale of your environment set to UTF-8 so that
the file's encoding is correct and so that the operating system handles
it correctly. For a script that executes in a Web environment, the
script must handle the character encoding properly for its interaction
with the MySQL server, and it must generate pages that correctly
indicate the encoding so that browsers know now to display the content
of the pages.


File: manual.info,  Node: charset-collations,  Next: charset-repertoire,  Prev: charset-connection,  Up: charset

9.1.5 Collation Issues
----------------------

* Menu:

* charset-collate::              Using `COLLATE' in SQL Statements
* charset-collate-precedence::   `COLLATE' Clause Precedence
* charset-binary-op::            `BINARY' Operator
* charset-collate-tricky::       Some Special Cases Where the Collation Determination Is Tricky
* charset-collation-charset::    Collations Must Be for the Right Character Set
* charset-collation-effect::     Examples of the Effect of Collation

The following sections discuss various aspects of character set
collations.


File: manual.info,  Node: charset-collate,  Next: charset-collate-precedence,  Prev: charset-collations,  Up: charset-collations

9.1.5.1 Using `COLLATE' in SQL Statements
.........................................

With the `COLLATE' clause, you can override whatever the default
collation is for a comparison.  `COLLATE' may be used in various parts
of SQL statements. Here are some examples:

   * With `ORDER BY':

          SELECT k
          FROM t1
          ORDER BY k COLLATE latin1_german2_ci;

   * With `AS':

          SELECT k COLLATE latin1_german2_ci AS k1
          FROM t1
          ORDER BY k1;

   * With `GROUP BY':

          SELECT k
          FROM t1
          GROUP BY k COLLATE latin1_german2_ci;

   * With aggregate functions:

          SELECT MAX(k COLLATE latin1_german2_ci)
          FROM t1;

   * With `DISTINCT':

          SELECT DISTINCT k COLLATE latin1_german2_ci
          FROM t1;

   * With `WHERE':

               SELECT *
               FROM t1
               WHERE _latin1 'Mu"ller' COLLATE latin1_german2_ci = k;

               SELECT *
               FROM t1
               WHERE k LIKE _latin1 'Mu"ller' COLLATE latin1_german2_ci;

   * With `HAVING':

          SELECT k
          FROM t1
          GROUP BY k
          HAVING k = _latin1 'Mu"ller' COLLATE latin1_german2_ci;


File: manual.info,  Node: charset-collate-precedence,  Next: charset-binary-op,  Prev: charset-collate,  Up: charset-collations

9.1.5.2 `COLLATE' Clause Precedence
...................................

The `COLLATE' clause has high precedence (higher than `||'), so the
following two expressions are equivalent:

     x || y COLLATE z
     x || (y COLLATE z)


File: manual.info,  Node: charset-binary-op,  Next: charset-collate-tricky,  Prev: charset-collate-precedence,  Up: charset-collations

9.1.5.3 `BINARY' Operator
.........................

The `BINARY' operator casts the string following it to a binary string.
This is an easy way to force a comparison to be done byte by byte
rather than character by character. `BINARY' also causes trailing
spaces to be significant.

     mysql> SELECT 'a' = 'A';
             -> 1
     mysql> SELECT BINARY 'a' = 'A';
             -> 0
     mysql> SELECT 'a' = 'a ';
             -> 1
     mysql> SELECT BINARY 'a' = 'a ';
             -> 0

`BINARY STR' is shorthand for `CAST(STR AS BINARY)'.

The `BINARY' attribute in character column definitions has a different
effect. A character column defined with the `BINARY' attribute is
assigned the binary collation of the column's character set. Every
character set has a binary collation. For example, the binary collation
for the `latin1' character set is `latin1_bin', so if the table default
character set is `latin1', these two column definitions are equivalent:

     CHAR(10) BINARY
     CHAR(10) CHARACTER SET latin1 COLLATE latin1_bin

The effect of `BINARY' as a column attribute differs from its effect
prior to MySQL 4.1. Formerly, `BINARY' resulted in a column that was
treated as a binary string. A binary string is a string of bytes that
has no character set or collation, which differs from a non-binary
character string that has a binary collation. For both types of
strings, comparisons are based on the numeric values of the string
unit, but for non-binary strings the unit is the character and some
character sets allow multi-byte characters.  *Note binary-varbinary::.

The use of `CHARACTER SET binary' in the definition of a `CHAR',
`VARCHAR', or `TEXT' column causes the column to be treated as a binary
data type. For example, the following pairs of definitions are
equivalent:

     CHAR(10) CHARACTER SET binary
     BINARY(10)

     VARCHAR(10) CHARACTER SET binary
     VARBINARY(10)

     TEXT CHARACTER SET binary
     BLOB


File: manual.info,  Node: charset-collate-tricky,  Next: charset-collation-charset,  Prev: charset-binary-op,  Up: charset-collations

9.1.5.4 Some Special Cases Where the Collation Determination Is Tricky
......................................................................

In the great majority of statements, it is obvious what collation MySQL
uses to resolve a comparison operation. For example, in the following
cases, it should be clear that the collation is the collation of column
`x':

     SELECT x FROM T ORDER BY x;
     SELECT x FROM T WHERE x = x;
     SELECT DISTINCT x FROM T;

However, when multiple operands are involved, there can be ambiguity.
For example:

     SELECT x FROM T WHERE x = 'Y';

Should this query use the collation of the column `x', or of the string
literal `'Y''?

Standard SQL resolves such questions using what used to be called
`coercibility' rules. Basically, this means: Both `x' and `'Y'' have
collations, so which collation takes precedence? This can be difficult
to resolve, but the following rules cover most situations:

   * An explicit `COLLATE' clause has a coercibility of 0. (Not
     coercible at all.)

   * The concatenation of two strings with different collations has a
     coercibility of 1.

   * The collation of a column or a stored routine parameter or local
     variable has a coercibility of 2.

   * A `system constant' (the string returned by functions such as
     `USER()' or `VERSION()') has a coercibility of 3.

   * A literal's collation has a coercibility of 4.

   * `NULL' or an expression that is derived from `NULL' has a
     coercibility of 5.

The preceding coercibility values are current for MySQL 5.1.

Those rules resolve ambiguities in the following manner:

   * Use the collation with the lowest coercibility value.

   * If both sides have the same coercibility, then:

        * If both sides are Unicode, or both sides are not Unicode, it
          is an error.

        * If one of the sides has a Unicode character set, and another
          side has a non-Unicode character set, the side with Unicode
          character set wins, and automatic character set conversion is
          applied to the non-Unicode side. For example, the following
          statement will not return an error:

               SELECT CONCAT(utf8_column, latin1_column) FROM t1;

          It will return a result, and the character set of the result
          will be `utf8'. The collation of the result will be the
          collation of `utf8_column'. Values of `latin1_column' will be
          automatically converted to `utf8' before concatenating.

Although automatic conversion is not in the SQL standard, the SQL
standard document does say that every character set is (in terms of
supported characters) a `subset' of Unicode. Because it is a well-known
principle that `what applies to a superset can apply to a subset,' we
believe that a collation for Unicode can apply for comparisons with
non-Unicode strings.

Examples:

`column1 = 'A''                      Use collation of `column1'
`column1 = 'A' COLLATE x'            Use collation of `'A' COLLATE x'
`column1 COLLATE x = 'A' COLLATE y'  Error

The `COERCIBILITY()' function can be used to determine the coercibility
of a string expression:

     mysql> SELECT COERCIBILITY('A' COLLATE latin1_swedish_ci);
             -> 0
     mysql> SELECT COERCIBILITY(VERSION());
             -> 3
     mysql> SELECT COERCIBILITY('A');
             -> 4

See *Note information-functions::.


File: manual.info,  Node: charset-collation-charset,  Next: charset-collation-effect,  Prev: charset-collate-tricky,  Up: charset-collations

9.1.5.5 Collations Must Be for the Right Character Set
......................................................

Each character set has one or more collations, but each collation is
associated with one and only one character set.  Therefore, the
following statement causes an error message because the `latin2_bin'
collation is not legal with the `latin1' character set:

     mysql> SELECT _latin1 'x' COLLATE latin2_bin;
     ERROR 1253 (42000): COLLATION 'latin2_bin' is not valid
     for CHARACTER SET 'latin1'


File: manual.info,  Node: charset-collation-effect,  Prev: charset-collation-charset,  Up: charset-collations

9.1.5.6 Examples of the Effect of Collation
...........................................

*Example 1: Sorting German Umlauts*

Suppose that column `X' in table `T' has these `latin1' column values:

     Muffler
     Mu"ller
     MX Systems
     MySQL

Suppose also that the column values are retrieved using the following
statement:

     SELECT X FROM T ORDER BY X COLLATE COLLATION_NAME;

The following table shows the resulting order of the values if we use
`ORDER BY' with different collations:

`latin1_swedish_ci'    `latin1_german1_ci'    `latin1_german2_ci'
Muffler                Muffler                Mu"ller
MX Systems             Mu"ller                Muffler
Mu"ller                MX Systems             MX Systems
MySQL                  MySQL                  MySQL

The character that causes the different sort orders in this example is
the U with two dots over it (`u"'), which the Germans call `U-umlaut.'

   * The first column shows the result of the `SELECT' using the
     Swedish/Finnish collating rule, which says that U-umlaut sorts
     with Y.

   * The second column shows the result of the `SELECT' using the
     German DIN-1 rule, which says that U-umlaut sorts with U.

   * The third column shows the result of the `SELECT' using the German
     DIN-2 rule, which says that U-umlaut sorts with UE.

*Example 2: Searching for German Umlauts*

Suppose that you have three tables that differ only by the character
set and collation used:

     mysql> CREATE TABLE german1 (
         ->   c CHAR(10)
         -> ) CHARACTER SET latin1 COLLATE latin1_german1_ci;
     mysql> CREATE TABLE german2 (
         ->   c CHAR(10)
         -> ) CHARACTER SET latin1 COLLATE latin1_german2_ci;
     mysql> CREATE TABLE germanutf8 (
         ->   c CHAR(10)
         -> ) CHARACTER SET utf8 COLLATE utf8_unicode_ci;

Each table contains two records:

     mysql> INSERT INTO german1 VALUES ('Bar'), ('Ba"r');
     mysql> INSERT INTO german2 VALUES ('Bar'), ('Ba"r');
     mysql> INSERT INTO germanutf8 VALUES ('Bar'), ('Ba"r');

Two of the above collations have an `A = A"' equality, and one has no
such equality (`latin1_german2_ci'). For that reason, you'll get these
results in comparisons:

     mysql> SELECT * FROM german1 WHERE c = 'Ba"r';
     +------+
     | c    |
     +------+
     | Bar  |
     | Ba"r  |
     +------+
     mysql> SELECT * FROM german2 WHERE c = 'Ba"r';
     +------+
     | c    |
     +------+
     | Ba"r  |
     +------+
     mysql> SELECT * FROM germanutf8 WHERE c = 'Ba"r';
     +------+
     | c    |
     +------+
     | Bar  |
     | Ba"r  |
     +------+

This is not a bug but rather a consequence of the sorting that
`latin1_german1_ci' or `utf8_unicode_ci' do (the sorting shown is done
according to the German DIN 5007 standard).


File: manual.info,  Node: charset-repertoire,  Next: charset-operations,  Prev: charset-collations,  Up: charset

9.1.6 String Repertoire
-----------------------

The _repertoire_ of a character set is the collection of characters in
the set.

As of MySQL 5.1.21, string expressions have a repertoire attribute,
which can have two values:

   * `ASCII': The expression can contain only characters in the Unicode
     range `U+0000' to `U+007F'.

   * `UNICODE': The expression can contain characters in the Unicode
     range `U+0000' to `U+FFFF'.

The `ASCII' range is a subset of `UNICODE' range, so a string with
`ASCII' repertoire can be converted safely without loss of information
to the character set of any string with `UNICODE' repertoire or to a
character set that is a superset of `ASCII'. (All MySQL character sets
are supersets of `ASCII' with the exception of `swe7', which reuses some
punctuation characters for Swedish accented characters.) The use of
repertoire enables character set conversion in expressions for many
cases where MySQL would otherwise return an `illegal mix of collations'
error.

The following discussion provides examples of expressions and their
repertoires, and describes how the use of repertoire changes string
expression evaluation:

   * The repertoire for string constants depends on string content:

          SET NAMES utf8; SELECT 'abc';
          SELECT _utf8'def';
          SELECT N'MySQL';

     Although the character set is `utf8' in each of the preceding
     cases, the strings do not actually contain any characters outside
     the ASCII range, so their repertoire is `ASCII' rather than
     `UNICODE'.

   * Columns having the `ascii' character set have `ASCII' repertoire
     because of their character set. In the following table, `c1' has
     `ASCII' repertoire:

          CREATE TABLE t1 (c1 CHAR(1) CHARACTER SET ascii);

     The following example illustrates how repertoire enables a result
     to be determined in a case where an error occurs without
     repertoire:

          CREATE TABLE t1 (
            c1 CHAR(1) CHARACTER SET latin1,
            c2 CHAR(1) CHARACTER SET ascii
          );
          INSERT INTO t1 VALUES ('a','b');
          SELECT CONCAT(c1,c2) FROM t1;

     Without repertoire, this error occurs:

          ERROR 1267 (HY000): Illegal mix of collations (latin1_swedish_ci,IMPLICIT)
          and (ascii_general_ci,IMPLICIT) for operation 'concat'

     Using repertoire, subset to superset (`ascii' to `latin1')
     conversion can occur and a result is returned:

          +---------------+
          | CONCAT(c1,c2) |
          +---------------+
          | ab            |
          +---------------+

   * Functions with one string argument inherit the repertoire of their
     argument. The result of `UPPER(_utf8'ABC')' has `ASCII'
     repertoire, because its argument has `ASCII' repertoire.

   * For functions that return a string but do not have string
     arguments and use `character_set_connection' as the result
     character set, the result repertoire is `ASCII' if
     `character_set_connection' is `ascii', and `UNICODE' otherwise:

          FORMAT(NUMERIC_COLUMN, 4);

     Use of repertoire changes how MySQL evaluates the following
     example:

          SET NAMES ascii;
          CREATE TABLE t1 (a INT, b VARCHAR(10) CHARACTER SET latin1);
          INSERT INTO t1 VALUES (1,'b');
          SELECT CONCAT(FORMAT(a, 4), b) FROM t1;

     Without repertoire, this error occurs:

          ERROR 1267 (HY000): Illegal mix of collations (ascii_general_ci,COERCIBLE)
          and (latin1_swedish_ci,IMPLICIT) for operation 'concat'

     With repertoire, a result is returned:

          +-------------------------+
          | CONCAT(FORMAT(a, 4), b) |
          +-------------------------+
          | 1.0000b                 |
          +-------------------------+

   * Functions with two or more string arguments use the `widest'
     argument repertoire for the result repertoire (`UNICODE' is wider
     than `ASCII'). Consider the following `CONCAT()' calls:

          CONCAT(_ucs2 0x0041, _ucs2 0x0042)
          CONCAT(_ucs2 0x0041, _ucs2 0x00C2)

     For the first call, the repertoire is `ASCII' because both
     arguments are within the range of the `ascii' character set. For
     the second call, the repertoire is `UNICODE' because the second
     argument is outside the `ascii' character set range.

   * The repertoire for function return values is determined based only
     on the repertoire of the arguments that affect the result's
     character set and collation.

          IF(column1 < column2, 'smaller', 'greater')

     The result repertoire is `ASCII' because the two string arguments
     (the second argument and the third argument) both have `ASCII'
     repertoire. The first argument does not matter for the result
     repertoire, even if the expression uses string values.


File: manual.info,  Node: charset-operations,  Next: charset-unicode,  Prev: charset-repertoire,  Up: charset

9.1.7 Operations Affected by Character Set Support
--------------------------------------------------

* Menu:

* charset-result::               Result Strings
* charset-convert::              `CONVERT()' and `CAST()'
* charset-show::                 `SHOW' Statements and `INFORMATION_SCHEMA'

This section describes operations that take character set information
into account.


File: manual.info,  Node: charset-result,  Next: charset-convert,  Prev: charset-operations,  Up: charset-operations

9.1.7.1 Result Strings
......................

MySQL has many operators and functions that return a string.  This
section answers the question: What is the character set and collation
of such a string?

For simple functions that take string input and return a string result
as output, the output's character set and collation are the same as
those of the principal input value.  For example, `UPPER(X)' returns a
string whose character string and collation are the same as that of X.
The same applies for `INSTR()', `LCASE()', `LOWER()', `LTRIM()',
`MID()', `REPEAT()', `REPLACE()', `REVERSE()', `RIGHT()', `RPAD()',
`RTRIM()', `SOUNDEX()', `SUBSTRING()', `TRIM()', `UCASE()', and
`UPPER()'.

Note: The `REPLACE()' function, unlike all other functions, always
ignores the collation of the string input and performs a case-sensitive
comparison.

If a string input or function result is a binary string, the string has
no character set or collation. This can be checked by using the
`CHARSET()' and `COLLATION()' functions, both of which return `binary'
to indicate that their argument is a binary string:

     mysql> SELECT CHARSET(BINARY 'a'), COLLATION(BINARY 'a');
     +---------------------+-----------------------+
     | CHARSET(BINARY 'a') | COLLATION(BINARY 'a') |
     +---------------------+-----------------------+
     | binary              | binary                |
     +---------------------+-----------------------+

For operations that combine multiple string inputs and return a single
string output, the `aggregation rules' of standard SQL apply for
determining the collation of the result:

   * If an explicit `COLLATE X' occurs, use X.

   * If explicit `COLLATE X' and `COLLATE Y' occur, raise an error.

   * Otherwise, if all collations are X, use X.

   * Otherwise, the result has no collation.

For example, with `CASE ... WHEN a THEN b WHEN b THEN c COLLATE X END',
the resulting collation is X. The same applies for `UNION', `||',
`CONCAT()', `ELT()', `GREATEST()', `IF()', and `LEAST()'.

For operations that convert to character data, the character set and
collation of the strings that result from the operations are defined by
the `character_set_connection' and `collation_connection' system
variables. This applies only to `CAST()', `CONV()', `FORMAT()',
`HEX()', and `SPACE()'.

If you are uncertain about the character set or collation of the result
returned by a string function, you can use the `CHARSET()' or
`COLLATION()' function to find out:

     mysql> SELECT USER(), CHARSET(USER()), COLLATION(USER());
     +----------------+-----------------+-------------------+
     | USER()         | CHARSET(USER()) | COLLATION(USER()) |
     +----------------+-----------------+-------------------+
     | test@localhost | utf8            | utf8_general_ci   |
     +----------------+-----------------+-------------------+


File: manual.info,  Node: charset-convert,  Next: charset-show,  Prev: charset-result,  Up: charset-operations

9.1.7.2 `CONVERT()' and `CAST()'
................................

`CONVERT()' provides a way to convert data between different character
sets. The syntax is:

     CONVERT(EXPR USING TRANSCODING_NAME)

In MySQL, transcoding names are the same as the corresponding character
set names.

Examples:

     SELECT CONVERT(_latin1'Mu"ller' USING utf8);
     INSERT INTO utf8table (utf8column)
         SELECT CONVERT(latin1field USING utf8) FROM latin1table;

`CONVERT(... USING ...)' is implemented according to the standard SQL
specification.

You may also use `CAST()' to convert a string to a different character
set. The syntax is:

     CAST(CHARACTER_STRING AS CHARACTER_DATA_TYPE CHARACTER SET CHARSET_NAME)

Example:

     SELECT CAST(_latin1'test' AS CHAR CHARACTER SET utf8);

If you use `CAST()' without specifying `CHARACTER SET', the resulting
character set and collation are defined by the
`character_set_connection' and `collation_connection' system variables.
If you use `CAST()' with `CHARACTER SET X', the resulting character set
and collation are `X' and the default collation of `X'.

You may not use a `COLLATE' clause inside a `CAST()', but you may use it
outside. That is, `CAST(... COLLATE ...)' is illegal, but `CAST(...)
COLLATE ...' is legal.

Example:

     SELECT CAST(_latin1'test' AS CHAR CHARACTER SET utf8) COLLATE utf8_bin;


File: manual.info,  Node: charset-show,  Prev: charset-convert,  Up: charset-operations

9.1.7.3 `SHOW' Statements and `INFORMATION_SCHEMA'
..................................................

Several `SHOW' statements provide additional character set information.
These include `SHOW CHARACTER SET', `SHOW COLLATION', `SHOW CREATE
DATABASE', `SHOW CREATE TABLE' and `SHOW COLUMNS'. These statements are
described here briefly. For more information, see *Note show::.

`INFORMATION_SCHEMA' has several tables that contain information
similar to that displayed by the `SHOW' statements. For example, the
`CHARACTER_SETS' and `COLLATIONS' tables contain the information
displayed by `SHOW CHARACTER SET' and `SHOW COLLATION'. See *Note
information-schema::.

The `SHOW CHARACTER SET' command shows all available character sets. It
takes an optional `LIKE' clause that indicates which character set
names to match. For example:

     mysql> SHOW CHARACTER SET LIKE 'latin%';
     +---------+-----------------------------+-------------------+--------+
     | Charset | Description                 | Default collation | Maxlen |
     +---------+-----------------------------+-------------------+--------+
     | latin1  | cp1252 West European        | latin1_swedish_ci |      1 |
     | latin2  | ISO 8859-2 Central European | latin2_general_ci |      1 |
     | latin5  | ISO 8859-9 Turkish          | latin5_turkish_ci |      1 |
     | latin7  | ISO 8859-13 Baltic          | latin7_general_ci |      1 |
     +---------+-----------------------------+-------------------+--------+

The output from `SHOW COLLATION' includes all available character sets.
It takes an optional `LIKE' clause that indicates which collation names
to match. For example:

     mysql> SHOW COLLATION LIKE 'latin1%';
     +-------------------+---------+----+---------+----------+---------+
     | Collation         | Charset | Id | Default | Compiled | Sortlen |
     +-------------------+---------+----+---------+----------+---------+
     | latin1_german1_ci | latin1  |  5 |         |          |       0 |
     | latin1_swedish_ci | latin1  |  8 | Yes     | Yes      |       0 |
     | latin1_danish_ci  | latin1  | 15 |         |          |       0 |
     | latin1_german2_ci | latin1  | 31 |         | Yes      |       2 |
     | latin1_bin        | latin1  | 47 |         | Yes      |       0 |
     | latin1_general_ci | latin1  | 48 |         |          |       0 |
     | latin1_general_cs | latin1  | 49 |         |          |       0 |
     | latin1_spanish_ci | latin1  | 94 |         |          |       0 |
     +-------------------+---------+----+---------+----------+---------+

`SHOW CREATE DATABASE' displays the `CREATE DATABASE' statement that
creates a given database:

     mysql> SHOW CREATE DATABASE test;
     +----------+-----------------------------------------------------------------+
     | Database | Create Database                                                 |
     +----------+-----------------------------------------------------------------+
     | test     | CREATE DATABASE `test` /*!40100 DEFAULT CHARACTER SET latin1 */ |
     +----------+-----------------------------------------------------------------+

If no `COLLATE' clause is shown, the default collation for the
character set applies.

`SHOW CREATE TABLE' is similar, but displays the `CREATE TABLE'
statement to create a given table. The column definitions indicate any
character set specifications, and the table options include character
set information.

The `SHOW COLUMNS' statement displays the collations of a table's
columns when invoked as `SHOW FULL COLUMNS'. Columns with `CHAR',
`VARCHAR', or `TEXT' data types have collations. Numeric and other
non-character types have no collation (indicated by `NULL' as the
`Collation' value). For example:

     mysql> SHOW FULL COLUMNS FROM person\G
     *************************** 1. row ***************************
          Field: id
           Type: smallint(5) unsigned
      Collation: NULL
           Null: NO
            Key: PRI
        Default: NULL
          Extra: auto_increment
     Privileges: select,insert,update,references
        Comment:
     *************************** 2. row ***************************
          Field: name
           Type: char(60)
      Collation: latin1_swedish_ci
           Null: NO
            Key:
        Default:
          Extra:
     Privileges: select,insert,update,references
        Comment:

The character set is not part of the display but is implied by the
collation name.


File: manual.info,  Node: charset-unicode,  Next: charset-metadata,  Prev: charset-operations,  Up: charset

9.1.8 Unicode Support
---------------------

MySQL 5.1 supports two character sets for storing Unicode data:

   * `ucs2', the UCS-2 encoding of the Unicode character set using 16
     bits per character

   * `utf8', a UTF-8 encoding of the Unicode character set using one to
     three bytes per character

These two character sets support the characters from the Basic
Multilingual Plane (BMP) of Unicode Version 3.0. BMP characters have
these characteristics:

   * Their code values are between 0 and 65535 (or `U+0000' .. `U+FFFF')

   * They can be encoded with a fixed 16-bit word, as in `ucs2'

   * They can be encoded with 8, 16, or 24 bits, as in `utf8'

   * They are sufficient for almost all characters in major languages

The `ucs2' and `utf8' character sets do not support supplementary
characters that lie outside the BMP.

A similar set of collations is available for each Unicode character
set. For example, each has a Danish collation, the names of which are
`ucs2_danish_ci' and `utf8_danish_ci'. All Unicode collations are
listed at *Note charset-unicode-sets::.

In UCS-2, every character is represented by a two-byte Unicode code
with the most significant byte first. For example: `LATIN CAPITAL
LETTER A' has the code `0x0041' and it is stored as a two-byte
sequence: `0x00 0x41'. `CYRILLIC SMALL LETTER YERU' (Unicode `0x044B')
is stored as a two-byte sequence: `0x04 0x4B'. For Unicode characters
and their codes, please refer to the Unicode Home Page
(http://www.unicode.org/).

The MySQL implementation of UCS-2 stores characters in big-endian byte
order and does not use a byte order mark (BOM) at the beginning of
UCS-2 values. Other database systems might use little-endian byte order
or a BOM, in which case, conversion of UCS-2 values will need to be
performed when transferring data between those systems and MySQL.

UTF-8 (Unicode Transformation Format with 8-bit units) is an
alternative way to store Unicode data. It is implemented according to
RFC 3629. RFC 3629 describes encoding sequences that take from one to
four bytes. Currently, MySQL support for UTF-8 does not include
four-byte sequences. (An older standard for UTF-8 encoding is given by
RFC 2279, which describes UTF-8 sequences that take from one to six
bytes. RFC 3629 renders RFC 2279 obsolete; for this reason, sequences
with five and six bytes are no longer used.)

The idea of UTF-8 is that various Unicode characters are encoded using
byte sequences of different lengths:

   * Basic Latin letters, digits, and punctuation signs use one byte.

   * Most European and Middle East script letters fit into a two-byte
     sequence: extended Latin letters (with tilde, macron, acute, grave
     and other accents), Cyrillic, Greek, Armenian, Hebrew, Arabic,
     Syriac, and others.

   * Korean, Chinese, and Japanese ideographs use three-byte sequences.

MySQL uses no BOM for UTF-8 values.

*Tip*: To save space with UTF-8, use `VARCHAR' instead of `CHAR'.
Otherwise, MySQL must reserve three bytes for each character in a `CHAR
CHARACTER SET utf8' column because that is the maximum possible length.
For example, MySQL must reserve 30 bytes for a `CHAR(10) CHARACTER SET
utf8' column.

UCS-2 cannot be used as a client character set, which means that `SET
NAMES 'ucs2'' does not work. (See *Note charset-connection::.)

Client applications that need to communicate with the server using
Unicode should set the client character set accordingly; for example,
by issuing a `SET NAMES 'utf8'' statement. `ucs2' cannot be used as a
client character set, which means that it does not work for `SET NAMES'
or `SET CHARACTER SET'. (See *Note charset-connection::.)


File: manual.info,  Node: charset-metadata,  Next: charset-conversion,  Prev: charset-unicode,  Up: charset

9.1.9 UTF-8 for Metadata
------------------------

_Metadata_ is `the data about the data.' Anything that _describes_ the
database -- as opposed to being the _contents_ of the database -- is
metadata. Thus column names, database names, usernames, version names,
and most of the string results from `SHOW' are metadata. This is also
true of the contents of tables in `INFORMATION_SCHEMA', because those
tables by definition contain information about database objects.

Representation of metadata must satisfy these requirements:

   * All metadata must be in the same character set. Otherwise, neither
     the `SHOW' commands nor `SELECT' statements for tables in
     `INFORMATION_SCHEMA' would work properly because different rows in
     the same column of the results of these operations would be in
     different character sets.

   * Metadata must include all characters in all languages.  Otherwise,
     users would not be able to name columns and tables using their own
     languages.

To satisfy both requirements, MySQL stores metadata in a Unicode
character set, namely UTF-8. This does not cause any disruption if you
never use accented or non-Latin characters. But if you do, you should
be aware that metadata is in UTF-8.

The metadata requirements mean that the return values of the `USER()',
`CURRENT_USER()', `SESSION_USER()', `SYSTEM_USER()', `DATABASE()', and
`VERSION()' functions have the UTF-8 character set by default.

The server sets the `character_set_system' system variable to the name
of the metadata character set:

     mysql> SHOW VARIABLES LIKE 'character_set_system';
     +----------------------+-------+
     | Variable_name        | Value |
     +----------------------+-------+
     | character_set_system | utf8  |
     +----------------------+-------+

Storage of metadata using Unicode does _not_ mean that the server
returns headers of columns and the results of `DESCRIBE' functions in
the `character_set_system' character set by default. When you use
`SELECT column1 FROM t', the name `column1' itself is returned from the
server to the client in the character set determined by the value of
the `character_set_results' system variable, which has a default value
of `latin1'. If you want the server to pass metadata results back in a
different character set, use the `SET NAMES' statement to force the
server to perform character set conversion. `SET NAMES' sets the
`character_set_results' and other related system variables. (See *Note
charset-connection::.) Alternatively, a client program can perform the
conversion after receiving the result from the server. It is more
efficient for the client perform the conversion, but this option is not
always available for all clients.

If `character_set_results' is set to `NULL', no conversion is performed
and the server returns metadata using its original character set (the
set indicated by `character_set_system').

Error messages returned from the server to the client are converted to
the client character set automatically, as with metadata.

If you are using (for example) the `USER()' function for comparison or
assignment within a single statement, don't worry. MySQL performs some
automatic conversion for you.

     SELECT * FROM Table1 WHERE USER() = latin1_column;

This works because the contents of `latin1_column' are automatically
converted to UTF-8 before the comparison.

     INSERT INTO Table1 (latin1_column) SELECT USER();

This works because the contents of `USER()' are automatically converted
to `latin1' before the assignment.

Although automatic conversion is not in the SQL standard, the SQL
standard document does say that every character set is (in terms of
supported characters) a `subset' of Unicode. Because it is a well-known
principle that `what applies to a superset can apply to a subset,' we
believe that a collation for Unicode can apply for comparisons with
non-Unicode strings. For more information about coercion of strings,
see *Note charset-collate-tricky::.


File: manual.info,  Node: charset-conversion,  Next: charset-charsets,  Prev: charset-metadata,  Up: charset

9.1.10 Column Character Set Conversion
--------------------------------------

To convert a binary or non-binary string column to use a particular
character set, use `ALTER TABLE'.  For successful conversion to occur,
one of the following conditions must apply:

   * If the column has a binary data type (`BINARY', `VARBINARY',
     `BLOB'), all the values that it contains must be encoded using a
     single character set (the character set you're converting the
     column to). If you use a binary column to store information in
     multiple character sets, MySQL has no way to know which values use
     which character set and cannot convert the data properly.

   * If the column has a non-binary data type (`CHAR', `VARCHAR',
     `TEXT'), its contents should be encoded in the column's character
     set, not some other character set. If the contents are encoded in
     a different character set, you can convert the column to use a
     binary data type first, and then to a non-binary column with the
     desired character set.

Suppose that a table `t' has a binary column named `col1' defined as
`BINARY(50)'. Assuming that the information in the column is encoded
using a single character set, you can convert it to a non-binary column
that has that character set.  For example, if `col1' contains binary
data representing characters in the `greek' character set, you can
convert it as follows:

     ALTER TABLE t MODIFY col1 CHAR(50) CHARACTER SET greek;

Suppose that table `t' has a non-binary column named `col1' defined as
`CHAR(50) CHARACTER SET latin1' but you want to convert it to use
`utf8' so that you can store values from many languages. The following
statement accomplishes this:

     ALTER TABLE t MODIFY col1 CHAR(50) CHARACTER SET utf8;

Conversion may be lossy if the column contains characters that are not
in both character sets.

A special case occurs if you have old tables from MySQL 4.0 or earlier
where a non-binary column contains values that actually are encoded in
a character set different from the server's default character set. For
example, an application might have stored `sjis' values in a column,
even though MySQL's default character set was `latin1'. It is possible
to convert the column to use the proper character set but an additional
step is required. Suppose that the server's default character set was
`latin1' and `col1' is defined as `CHAR(50)' but its contents are
`sjis' values. The first step is to convert the column to a binary data
type, which removes the existing character set information without
performing any character conversion:

     ALTER TABLE t MODIFY col1 BINARY(50);

The next step is to convert the column to a non-binary data type with
the proper character set:

     ALTER TABLE t MODIFY col1 CHAR(50) CHARACTER SET sjis;

This procedure requires that the table not have been modified already
with statements such as `INSERT' or `UPDATE' after an upgrade to MySQL
4.1 or later. In that case, MySQL would store new values in the column
using `latin1', and the column will contain a mix of `sjis' and `latin1'
values and cannot be converted properly.

If you specified attributes when creating a column initially, you
should also specify them when altering the table with `ALTER TABLE'.
For example, if you specified `NOT NULL' and an explicit `DEFAULT'
value, you should also provide them in the `ALTER TABLE' statement.
Otherwise, the resulting column definition will not include those
attributes.


File: manual.info,  Node: charset-charsets,  Prev: charset-conversion,  Up: charset

9.1.11 Character Sets and Collations That MySQL Supports
--------------------------------------------------------

* Menu:

* charset-unicode-sets::         Unicode Character Sets
* charset-we-sets::              West European Character Sets
* charset-ce-sets::              Central European Character Sets
* charset-se-me-sets::           South European and Middle East Character Sets
* charset-baltic-sets::          Baltic Character Sets
* charset-cyrillic-sets::        Cyrillic Character Sets
* charset-asian-sets::           Asian Character Sets

MySQL supports 70+ collations for 30+ character sets. This section
indicates which character sets MySQL supports. There is one subsection
for each group of related character sets. For each character set, the
allowable collations are listed.

You can always list the available character sets and their default
collations with the `SHOW CHARACTER SET' statement:

     mysql> SHOW CHARACTER SET;
     +----------+-----------------------------+---------------------+
     | Charset  | Description                 | Default collation   |
     +----------+-----------------------------+---------------------+
     | big5     | Big5 Traditional Chinese    | big5_chinese_ci     |
     | dec8     | DEC West European           | dec8_swedish_ci     |
     | cp850    | DOS West European           | cp850_general_ci    |
     | hp8      | HP West European            | hp8_english_ci      |
     | koi8r    | KOI8-R Relcom Russian       | koi8r_general_ci    |
     | latin1   | cp1252 West European        | latin1_swedish_ci   |
     | latin2   | ISO 8859-2 Central European | latin2_general_ci   |
     | swe7     | 7bit Swedish                | swe7_swedish_ci     |
     | ascii    | US ASCII                    | ascii_general_ci    |
     | ujis     | EUC-JP Japanese             | ujis_japanese_ci    |
     | sjis     | Shift-JIS Japanese          | sjis_japanese_ci    |
     | hebrew   | ISO 8859-8 Hebrew           | hebrew_general_ci   |
     | tis620   | TIS620 Thai                 | tis620_thai_ci      |
     | euckr    | EUC-KR Korean               | euckr_korean_ci     |
     | koi8u    | KOI8-U Ukrainian            | koi8u_general_ci    |
     | gb2312   | GB2312 Simplified Chinese   | gb2312_chinese_ci   |
     | greek    | ISO 8859-7 Greek            | greek_general_ci    |
     | cp1250   | Windows Central European    | cp1250_general_ci   |
     | gbk      | GBK Simplified Chinese      | gbk_chinese_ci      |
     | latin5   | ISO 8859-9 Turkish          | latin5_turkish_ci   |
     | armscii8 | ARMSCII-8 Armenian          | armscii8_general_ci |
     | utf8     | UTF-8 Unicode               | utf8_general_ci     |
     | ucs2     | UCS-2 Unicode               | ucs2_general_ci     |
     | cp866    | DOS Russian                 | cp866_general_ci    |
     | keybcs2  | DOS Kamenicky Czech-Slovak  | keybcs2_general_ci  |
     | macce    | Mac Central European        | macce_general_ci    |
     | macroman | Mac West European           | macroman_general_ci |
     | cp852    | DOS Central European        | cp852_general_ci    |
     | latin7   | ISO 8859-13 Baltic          | latin7_general_ci   |
     | cp1251   | Windows Cyrillic            | cp1251_general_ci   |
     | cp1256   | Windows Arabic              | cp1256_general_ci   |
     | cp1257   | Windows Baltic              | cp1257_general_ci   |
     | binary   | Binary pseudo charset       | binary              |
     | geostd8  | GEOSTD8 Georgian            | geostd8_general_ci  |
     | cp932    | SJIS for Windows Japanese   | cp932_japanese_ci   |
     | eucjpms  | UJIS for Windows Japanese   | eucjpms_japanese_ci |
     +----------+-----------------------------+---------------------+

In cases where a character set has multiple collations, it might not be
clear which collation is most suitable for a given application. To
avoid choosing the wrong collation, it can be helpful to perform some
comparisons with representative data values to make sure that a given
collation sorts values the way you expect.

Collation-Charts.Org (http://www.collation-charts.org/) is a useful
site for information that shows how one collation compares to another.


File: manual.info,  Node: charset-unicode-sets,  Next: charset-we-sets,  Prev: charset-charsets,  Up: charset-charsets

9.1.11.1 Unicode Character Sets
...............................

MySQL 5.1 has two Unicode character sets:

   * `ucs2', the UCS-2 encoding of the Unicode character set using 16
     bits per character

   * `utf8', a UTF-8 encoding of the Unicode character set using one to
     three bytes per character

You can store text in about 650 languages using these character sets.
This section lists the collations available for each Unicode character
set. For general information about the character sets, see *Note
charset-unicode::.

A similar set of collations is available for each Unicode character
set. These are shown in the following list, where XXX represents the
character set name. For example, `XXX_danish_ci' represents the Danish
collations, the specific names of which are `ucs2_danish_ci' and
`utf8_danish_ci'.

   * `XXX_bin'

   * `XXX_czech_ci'

   * `XXX_danish_ci'

   * `XXX_esperanto_ci'

   * `XXX_estonian_ci'

   * `XXX_general_ci' (default)

   * `XXX_hungarian_ci'

   * `XXX_icelandic_ci'

   * `XXX_latvian_ci'

   * `XXX_lithuanian_ci'

   * `XXX_persian_ci'

   * `XXX_polish_ci'

   * `XXX_roman_ci'

   * `XXX_romanian_ci'

   * `XXX_slovak_ci'

   * `XXX_slovenian_ci'

   * `XXX_spanish2_ci'

   * `XXX_spanish_ci'

   * `XXX_swedish_ci'

   * `XXX_turkish_ci'

   * `XXX_unicode_ci'

The `XXX_hungarian_ci' collations were added in MySQL 5.1.5.

MySQL implements the `XXX_unicode_ci' collations according to the
Unicode Collation Algorithm (UCA) described at
`http://www.unicode.org/reports/tr10/'. The collation uses the
version-4.0.0 UCA weight keys:
`http://www.unicode.org/Public/UCA/4.0.0/allkeys-4.0.0.txt'.
Currently, the `XXX_unicode_ci' collations have only partial support
for the Unicode Collation Algorithm. Some characters are not supported
yet. Also, combining marks are not fully supported. This affects
primarily Vietnamese, Yoruba, and some smaller languages such as
Navajo. The following discussion uses `utf8_unicode_ci' for
concreteness.

For any Unicode character set, operations performed using the
`_general_ci' collation are faster than those for the `_unicode_ci'
collation. For example, comparisons for the `utf8_general_ci' collation
are faster, but slightly less correct, than comparisons for
`utf8_unicode_ci'. The reason for this is that `utf8_unicode_ci'
supports mappings such as expansions; that is, when one character
compares as equal to combinations of other characters. For example, in
German and some other languages ``ss'' is equal to ``ss''.
`utf8_unicode_ci' also supports contractions and ignorable characters.
`utf8_general_ci' is a legacy collation that does not support
expansions, contractions, or ignorable characters. It can make only
one-to-one comparisons between characters.

To further illustrate, the following equalities hold in both
`utf8_general_ci' and `utf8_unicode_ci' (for the effect this has in
comparisons or when doing searches, see *Note
charset-collation-effect::):

     A" = A
     O" = O
     U" = U

A difference between the collations is that this is true for
`utf8_general_ci':

     ss = s

Whereas this is true for `utf8_unicode_ci':

     ss = ss

MySQL implements language-specific collations for the `utf8' character
set only if the ordering with `utf8_unicode_ci' does not work well for
a language. For example, `utf8_unicode_ci' works fine for German and
French, so there is no need to create special `utf8' collations for
these two languages.

`utf8_general_ci' also is satisfactory for both German and French,
except that ``ss'' is equal to ``s'', and not to ``ss''. If this is
acceptable for your application, then you should use `utf8_general_ci'
because it is faster.  Otherwise, use `utf8_unicode_ci' because it is
more accurate.

`utf8_swedish_ci', like other `utf8' language-specific collations, is
derived from `utf8_unicode_ci' with additional language rules. For
example, in Swedish, the following relationship holds, which is not
something expected by a German or French speaker:

     U" = Y < O"

The `XXX_spanish_ci' and `XXX_spanish2_ci' collations correspond to
modern Spanish and traditional Spanish, respectively. In both
collations, ``ñ'' (n-tilde) is a separate letter between ``n'' and
``o''. In addition, for traditional Spanish, ``ch'' is a separate
letter between ``c'' and ``d'', and ``ll'' is a separate letter between
``l'' and ``m''

In the `XXX_roman_ci' collations, `I' and `J' compare as equal, and `U'
and `V' compare as equal.

For additional information about Unicode collations in MySQL, see
Collation-Charts.Org (utf8
(http://www.collation-charts.org/mysql60/by-charset.html#utf8)).


File: manual.info,  Node: charset-we-sets,  Next: charset-ce-sets,  Prev: charset-unicode-sets,  Up: charset-charsets

9.1.11.2 West European Character Sets
.....................................

Western European character sets cover most West European languages,
such as French, Spanish, Catalan, Basque, Portuguese, Italian,
Albanian, Dutch, German, Danish, Swedish, Norwegian, Finnish, Faroese,
Icelandic, Irish, Scottish, and English.

   * `ascii' (US ASCII) collations:

        * `ascii_bin'

        * `ascii_general_ci' (default)

   * `cp850' (DOS West European) collations:

        * `cp850_bin'

        * `cp850_general_ci' (default)

   * `dec8' (DEC Western European) collations:

        * `dec8_bin'

        * `dec8_swedish_ci' (default)

   * `hp8' (HP Western European) collations:

        * `hp8_bin'

        * `hp8_english_ci' (default)

   * `latin1' (cp1252 West European) collations:

        * `latin1_bin'

        * `latin1_danish_ci'

        * `latin1_general_ci'

        * `latin1_general_cs'

        * `latin1_german1_ci'

        * `latin1_german2_ci'

        * `latin1_spanish_ci'

        * `latin1_swedish_ci' (default)

     `latin1' is the default character set.  MySQL's `latin1' is the
     same as the Windows `cp1252' character set. This means it is the
     same as the official `ISO 8859-1' or IANA (Internet Assigned
     Numbers Authority) `latin1', except that IANA `latin1' treats the
     code points between `0x80' and `0x9f' as `undefined,' whereas
     `cp1252', and therefore MySQL's `latin1', assign characters for
     those positions. For example, `0x80' is the Euro sign. For the
     `undefined' entries in `cp1252', MySQL translates `0x81' to Unicode
     `0x0081', `0x8d' to `0x008d', `0x8f' to `0x008f', `0x90' to
     `0x0090', and `0x9d' to `0x009d'.

     The `latin1_swedish_ci' collation is the default that probably is
     used by the majority of MySQL customers. Although it is frequently
     said that it is based on the Swedish/Finnish collation rules,
     there are Swedes and Finns who disagree with this statement.

     The `latin1_german1_ci' and `latin1_german2_ci' collations are
     based on the DIN-1 and DIN-2 standards, where DIN stands for
     _Deutsches Institut fu"r Normung_ (the German equivalent of ANSI).
     DIN-1 is called the `dictionary collation' and DIN-2 is called the
     `phone book collation.' For an example of the effect this has in
     comparisons or when doing searches, see *Note
     charset-collation-effect::.

        * `latin1_german1_ci' (dictionary) rules:

               A" = A
               O" = O
               U" = U
               ss = s

        * `latin1_german2_ci' (phone-book) rules:

               A" = AE
               O" = OE
               U" = UE
               ss = ss

     For an example of the effect this has in comparisons or when doing
     searches, see *Note charset-collation-effect::.

     In the `latin1_spanish_ci' collation, ``ñ'' (n-tilde) is a
     separate letter between ``n'' and ``o''.

   * `macroman' (Mac West European) collations:

        * `macroman_bin'

        * `macroman_general_ci' (default)

   * `swe7' (7bit Swedish) collations:

        * `swe7_bin'

        * `swe7_swedish_ci' (default)

For additional information about Western European collations in MySQL,
see Collation-Charts.Org (ascii
(http://www.collation-charts.org/mysql60/by-charset.html#ascii), cp850
(http://www.collation-charts.org/mysql60/by-charset.html#cp850), dec8
(http://www.collation-charts.org/mysql60/by-charset.html#dec8), hp8
(http://www.collation-charts.org/mysql60/by-charset.html#hp8), latin1
(http://www.collation-charts.org/mysql60/by-charset.html#latin1),
macroman
(http://www.collation-charts.org/mysql60/by-charset.html#macroman),
swe7 (http://www.collation-charts.org/mysql60/by-charset.html#swe7)).


File: manual.info,  Node: charset-ce-sets,  Next: charset-se-me-sets,  Prev: charset-we-sets,  Up: charset-charsets

9.1.11.3 Central European Character Sets
........................................

MySQL provides some support for character sets used in the Czech
Republic, Slovakia, Hungary, Romania, Slovenia, Croatia, Poland, and
Serbia (Latin).

   * `cp1250' (Windows Central European) collations:

        * `cp1250_bin'

        * `cp1250_croatian_ci'

        * `cp1250_czech_cs'

        * `cp1250_general_ci' (default)

        * `cp1250_polish_ci'

   * `cp852' (DOS Central European) collations:

        * `cp852_bin'

        * `cp852_general_ci' (default)

   * `keybcs2' (DOS Kamenicky Czech-Slovak) collations:

        * `keybcs2_bin'

        * `keybcs2_general_ci' (default)

   * `latin2' (ISO 8859-2 Central European) collations:

        * `latin2_bin'

        * `latin2_croatian_ci'

        * `latin2_czech_cs'

        * `latin2_general_ci' (default)

        * `latin2_hungarian_ci'

   * `macce' (Mac Central European) collations:

        * `macce_bin'

        * `macce_general_ci' (default)

For additional information about Central European collations in MySQL,
see Collation-Charts.Org (cp1250
(http://www.collation-charts.org/mysql60/by-charset.html#cp1250), cp852
(http://www.collation-charts.org/mysql60/by-charset.html#cp852),
keybcs2
(http://www.collation-charts.org/mysql60/by-charset.html#keybcs2),
latin2 (http://www.collation-charts.org/mysql60/by-charset.html#latin2),
macce (http://www.collation-charts.org/mysql60/by-charset.html#macce)).


File: manual.info,  Node: charset-se-me-sets,  Next: charset-baltic-sets,  Prev: charset-ce-sets,  Up: charset-charsets

9.1.11.4 South European and Middle East Character Sets
......................................................

South European and Middle Eastern character sets supported by MySQL
include Armenian, Arabic, Georgian, Greek, Hebrew, and Turkish.

   * `armscii8' (ARMSCII-8 Armenian) collations:

        * `armscii8_bin'

        * `armscii8_general_ci' (default)

   * `cp1256' (Windows Arabic) collations:

        * `cp1256_bin'

        * `cp1256_general_ci' (default)

   * `geostd8' (GEOSTD8 Georgian) collations:

        * `geostd8_bin'

        * `geostd8_general_ci' (default)

   * `greek' (ISO 8859-7 Greek) collations:

        * `greek_bin'

        * `greek_general_ci' (default)

   * `hebrew' (ISO 8859-8 Hebrew) collations:

        * `hebrew_bin'

        * `hebrew_general_ci' (default)

   * `latin5' (ISO 8859-9 Turkish) collations:

        * `latin5_bin'

        * `latin5_turkish_ci' (default)

For additional information about South European and Middle Eastern
collations in MySQL, see Collation-Charts.Org (armscii8
(http://www.collation-charts.org/mysql60/by-charset.html#armscii8),
cp1256 (http://www.collation-charts.org/mysql60/by-charset.html#cp1256),
geostd8
(http://www.collation-charts.org/mysql60/by-charset.html#geostd8),
greek (http://www.collation-charts.org/mysql60/by-charset.html#greek),
hebrew (http://www.collation-charts.org/mysql60/by-charset.html#hebrew),
latin5
(http://www.collation-charts.org/mysql60/by-charset.html#latin5)).


File: manual.info,  Node: charset-baltic-sets,  Next: charset-cyrillic-sets,  Prev: charset-se-me-sets,  Up: charset-charsets

9.1.11.5 Baltic Character Sets
..............................

The Baltic character sets cover Estonian, Latvian, and Lithuanian
languages.

   * `cp1257' (Windows Baltic) collations:

        * `cp1257_bin'

        * `cp1257_general_ci' (default)

        * `cp1257_lithuanian_ci'

   * `latin7' (ISO 8859-13 Baltic) collations:

        * `latin7_bin'

        * `latin7_estonian_cs'

        * `latin7_general_ci' (default)

        * `latin7_general_cs'

For additional information about Baltic collations in MySQL, see
Collation-Charts.Org (cp1257
(http://www.collation-charts.org/mysql60/by-charset.html#cp1257),
latin7
(http://www.collation-charts.org/mysql60/by-charset.html#latin7)).


File: manual.info,  Node: charset-cyrillic-sets,  Next: charset-asian-sets,  Prev: charset-baltic-sets,  Up: charset-charsets

9.1.11.6 Cyrillic Character Sets
................................

The Cyrillic character sets and collations are for use with Belarusian,
Bulgarian, Russian, Ukrainian, and Serbian (Cyrillic) languages.

   * `cp1251' (Windows Cyrillic) collations:

        * `cp1251_bin'

        * `cp1251_bulgarian_ci'

        * `cp1251_general_ci' (default)

        * `cp1251_general_cs'

        * `cp1251_ukrainian_ci'

   * `cp866' (DOS Russian) collations:

        * `cp866_bin'

        * `cp866_general_ci' (default)

   * `koi8r' (KOI8-R Relcom Russian) collations:

        * `koi8r_bin'

        * `koi8r_general_ci' (default)

   * `koi8u' (KOI8-U Ukrainian) collations:

        * `koi8u_bin'

        * `koi8u_general_ci' (default)

For additional information about Cyrillic collations in MySQL, see
Collation-Charts.Org (cp1251
(http://www.collation-charts.org/mysql60/by-charset.html#cp1251), cp866
(http://www.collation-charts.org/mysql60/by-charset.html#cp866), koi8r
(http://www.collation-charts.org/mysql60/by-charset.html#koi8r), koi8u
(http://www.collation-charts.org/mysql60/by-charset.html#koi8u)).  ).


File: manual.info,  Node: charset-asian-sets,  Prev: charset-cyrillic-sets,  Up: charset-charsets

9.1.11.7 Asian Character Sets
.............................

* Menu:

* charset-cp932::                The `cp932' Character Set

The Asian character sets that we support include Chinese, Japanese,
Korean, and Thai. These can be complicated. For example, the Chinese
sets must allow for thousands of different characters. See *Note
charset-cp932::, for additional information about the `cp932' and
`sjis' character sets.

For answers to some common questions and problems relating support for
Asian character sets in MySQL, see *Note faqs-cjk::.

   * `big5' (Big5 Traditional Chinese) collations:

        * `big5_bin'

        * `big5_chinese_ci' (default)

   * `cp932' (SJIS for Windows Japanese) collations:

        * `cp932_bin'

        * `cp932_japanese_ci' (default)

   * `eucjpms' (UJIS for Windows Japanese) collations:

        * `eucjpms_bin'

        * `eucjpms_japanese_ci' (default)

   * `euckr' (EUC-KR Korean) collations:

        * `euckr_bin'

        * `euckr_korean_ci' (default)

   * `gb2312' (GB2312 Simplified Chinese) collations:

        * `gb2312_bin'

        * `gb2312_chinese_ci' (default)

   * `gbk' (GBK Simplified Chinese) collations:

        * `gbk_bin'

        * `gbk_chinese_ci' (default)

   * `sjis' (Shift-JIS Japanese) collations:

        * `sjis_bin'

        * `sjis_japanese_ci' (default)

   * `tis620' (TIS620 Thai) collations:

        * `tis620_bin'

        * `tis620_thai_ci' (default)

   * `ujis' (EUC-JP Japanese) collations:

        * `ujis_bin'

        * `ujis_japanese_ci' (default)

For additional information about Asian collations in MySQL, see
Collation-Charts.Org (big5
(http://www.collation-charts.org/mysql60/by-charset.html#big5), cp932
(http://www.collation-charts.org/mysql60/by-charset.html#cp932),
eucjpms
(http://www.collation-charts.org/mysql60/by-charset.html#eucjpms),
euckr (http://www.collation-charts.org/mysql60/by-charset.html#euckr),
gb2312 (http://www.collation-charts.org/mysql60/by-charset.html#gb2312),
gbk (http://www.collation-charts.org/mysql60/by-charset.html#gbk), sjis
(http://www.collation-charts.org/mysql60/by-charset.html#sjis), tis620
(http://www.collation-charts.org/mysql60/by-charset.html#tis620), ujis
(http://www.collation-charts.org/mysql60/by-charset.html#ujis)).


File: manual.info,  Node: charset-cp932,  Prev: charset-asian-sets,  Up: charset-asian-sets

9.1.11.8 The `cp932' Character Set
..................................

*Why is `cp932' needed?*

In MySQL, the `sjis' character set corresponds to the `Shift_JIS'
character set defined by IANA, which supports JIS X0201 and JIS X0208
characters. (See `http://www.iana.org/assignments/character-sets'.)

However, the meaning of `SHIFT JIS' as a descriptive term has become
very vague and it often includes the extensions to `Shift_JIS' that are
defined by various vendors.

For example, `SHIFT JIS' used in Japanese Windows environments is a
Microsoft extension of `Shift_JIS' and its exact name is `Microsoft
Windows Codepage : 932' or `cp932'. In addition to the characters
supported by `Shift_JIS', `cp932' supports extension characters such as
NEC special characters, NEC selected -- IBM extended characters, and
IBM extended characters.

Many Japanese users have experienced problems using these extension
characters. These problems stem from the following factors:

   * MySQL automatically converts character sets.

   * Character sets are converted via Unicode (`ucs2').

   * The `sjis' character set does not support the conversion of these
     extension characters.

   * There are several conversion rules from so-called `SHIFT JIS' to
     Unicode, and some characters are converted to Unicode differently
     depending on the conversion rule. MySQL supports only one of these
     rules (described later).

The MySQL `cp932' character set is designed to solve these problems.

Because MySQL supports character set conversion, it is important to
separate IANA `Shift_JIS' and `cp932' into two different character sets
because they provide different conversion rules.

*How does `cp932' differ from `sjis'?*

The `cp932' character set differs from `sjis' in the following ways:

   * `cp932' supports NEC special characters, NEC selected -- IBM
     extended characters, and IBM selected characters.

   * Some `cp932' characters have two different code points, both of
     which convert to the same Unicode code point. When converting from
     Unicode back to `cp932', one of the code points must be selected.
     For this `round trip conversion,' the rule recommended by
     Microsoft is used. (See
     `http://support.microsoft.com/kb/170559/EN-US/'.)

     The conversion rule works like this:

        * If the character is in both JIS X 0208 and NEC special
          characters, use the code point of JIS X 0208.

        * If the character is in both NEC special characters and IBM
          selected characters, use the code point of NEC special
          characters.

        * If the character is in both IBM selected characters and NEC
          selected -- IBM extended characters, use the code point of
          IBM extended characters.

     The table shown at
     `http://www.microsoft.com/globaldev/reference/dbcs/932.htm'
     provides information about the Unicode values of `cp932'
     characters. For `cp932' table entries with characters under which
     a four-digit number appears, the number represents the
     corresponding Unicode (`ucs2') encoding. For table entries with an
     underlined two-digit value appears, there is a range of `cp932'
     character values that begin with those two digits. Clicking such a
     table entry takes you to a page that displays the Unicode value for
     each of the `cp932' characters that begin with those digits.

     The following links are of special interest. They correspond to
     the encodings for the following sets of characters:

        * NEC special characters:

               `http://www.microsoft.com/globaldev/reference/dbcs/932/932_87.htm'

        * NEC selected -- IBM extended characters:

               `http://www.microsoft.com/globaldev/reference/dbcs/932/932_ED.htm'
               `http://www.microsoft.com/globaldev/reference/dbcs/932/932_EE.htm'

        * IBM selected characters:

               `http://www.microsoft.com/globaldev/reference/dbcs/932/932_FA.htm'
               `http://www.microsoft.com/globaldev/reference/dbcs/932/932_FB.htm'
               `http://www.microsoft.com/globaldev/reference/dbcs/932/932_FC.htm'

   * `cp932' supports conversion of user-defined characters in
     combination with `eucjpms', and solves the problems with
     `sjis'/`ujis' conversion. For details, please refer to
     `http://www.opengroup.or.jp/jvc/cde/sjis-euc-e.html'.

For some characters, conversion to and from `ucs2' is different for
`sjis' and `cp932'. The following tables illustrate these differences.

Conversion to `ucs2':

*`sjis'/`cp932' Value*   *`sjis' -> `ucs2'        *`cp932' -> `ucs2'
                         Conversion*              Conversion*
5C                       005C                     005C
7E                       007E                     007E
815C                     2015                     2015
815F                     005C                     FF3C
8160                     301C                     FF5E
8161                     2016                     2225
817C                     2212                     FF0D
8191                     00A2                     FFE0
8192                     00A3                     FFE1
81CA                     00AC                     FFE2

Conversion from `ucs2':

*`ucs2' value*           *`ucs2' -> `sjis'        *`ucs2' -> `cp932'
                         Conversion*              Conversion*
005C                     815F                     5C
007E                     7E                       7E
00A2                     8191                     3F
00A3                     8192                     3F
00AC                     81CA                     3F
2015                     815C                     815C
2016                     8161                     3F
2212                     817C                     3F
2225                     3F                       8161
301C                     8160                     3F
FF0D                     3F                       817C
FF3C                     3F                       815F
FF5E                     3F                       8160
FFE0                     3F                       8191
FFE1                     3F                       8192
FFE2                     3F                       81CA

Users of any Japanese character sets should be aware that using
`--character-set-client-handshake' (or
`--skip-character-set-client-handshake') has an important effect. See
*Note server-options::.


File: manual.info,  Node: charset-configuration,  Next: error-message-language,  Prev: charset,  Up: internationalization-localization

9.2 The Character Set Used for Data and Sorting
===============================================

* Menu:

* german-character-set::         Using the German Character Set

By default, MySQL uses the `latin1' (cp1252 West European) character
set and the `latin1_swedish_ci' collation that sorts according to
Swedish/Finnish rules. These defaults are suitable for the United
States and most of Western Europe.

All MySQL binary distributions are compiled with
`--with-extra-charsets=complex'. This adds code to all standard
programs that enables them to handle `latin1' and all multi-byte
character sets within the binary. Other character sets are loaded from
a character-set definition file when needed.

The character set determines what characters are allowed in
identifiers. The collation determines how strings are sorted by the
`ORDER BY' and `GROUP BY' clauses of the `SELECT' statement.

You can change the default server character set and collation with the
`--character-set-server' and `--collation-server' options when you
start the server. The collation must be a legal collation for the
default character set. (Use the `SHOW COLLATION' statement to determine
which collations are available for each character set.) See *Note
server-options::.

The character sets available depend on the `--with-charset=CHARSET_NAME'
and `--with-extra-charsets=LIST-OF-CHARSETS | complex | all | none'
options to `configure', and the character set configuration files
listed in `SHAREDIR/charsets/Index'.  See *Note configure-options::.

If you change the character set when running MySQL, that may also
change the sort order. Consequently, you must run `myisamchk -r -q
--set-collation=COLLATION_NAME' on all `MyISAM' tables, or your indexes
may not be ordered correctly.

When a client connects to a MySQL server, the server indicates to the
client what the server's default character set is. The client switches
to this character set for this connection.

You should use *Note `mysql_real_escape_string()':
mysql-real-escape-string. when escaping strings for an SQL query.
*Note `mysql_real_escape_string()': mysql-real-escape-string. is
identical to the old *Note `mysql_escape_string()':
mysql-escape-string. function, except that it takes the `MYSQL'
connection handle as the first parameter so that the appropriate
character set can be taken into account when escaping characters.

If the client is compiled with paths that differ from where the server
is installed and the user who configured MySQL didn't include all
character sets in the MySQL binary, you must tell the client where it
can find the additional character sets it needs if the server runs with
a different character set from the client.  You can do this by
specifying a `--character-sets-dir' option to indicate the path to the
directory in which the dynamic MySQL character sets are stored. For
example, you can put the following in an option file:

     [client]
     character-sets-dir=/usr/local/mysql/share/mysql/charsets

You can force the client to use specific character set as follows:

     [client]
     default-character-set=CHARSET_NAME

This is normally unnecessary, however.


File: manual.info,  Node: german-character-set,  Prev: charset-configuration,  Up: charset-configuration

9.2.1 Using the German Character Set
------------------------------------

In MySQL 5.1, character set and collation are specified separately.
This means that if you want German sort order, you should select the
`latin1' character set and either the `latin1_german1_ci' or
`latin1_german2_ci' collation. For example, to start the server with
the `latin1_german1_ci' collation, use the
`--character-set-server=latin1' and
`--collation-server=latin1_german1_ci' options.

For information on the differences between these two collations, see
*Note charset-we-sets::.


File: manual.info,  Node: error-message-language,  Next: adding-character-set,  Prev: charset-configuration,  Up: internationalization-localization

9.3 Setting the Error Message Language
======================================

By default, `mysqld' produces error messages in English, but they can
also be displayed in any of these other languages: Czech, Danish,
Dutch, Estonian, French, German, Greek, Hungarian, Italian, Japanese,
Korean, Norwegian, Norwegian-ny, Polish, Portuguese, Romanian, Russian,
Slovak, Spanish, or Swedish.

To start `mysqld' with a particular language for error messages, use
the `--language' or `-L' option. The option value can be a language
name or the full path to the error message file. For example:

     shell> mysqld --language=swedish

Or:

     shell> mysqld --language=/usr/local/share/swedish

The language name should be specified in lowercase.

By default, the language files are located in the `share/LANGUAGE'
directory under the MySQL base directory.

You can also change the content of the error messages produced by the
server. Details can be found in the MySQL Internals manual, available at
`http://forge.mysql.com/wiki/MySQL_Internals_Error_Messages'.  If you
upgrade to a newer version of MySQL after changing the error messages,
remember to repeat your changes after the upgrade.


File: manual.info,  Node: adding-character-set,  Next: adding-collation,  Prev: error-message-language,  Up: internationalization-localization

9.4 Adding a New Character Set
==============================

* Menu:

* character-arrays::             The Character Definition Arrays
* string-collating::             String Collating Support
* multi-byte-characters::        Multi-Byte Character Support

This section discusses the procedure for adding a new character set to
MySQL. You must have a MySQL source distribution to use these
instructions. The proper procedure depends on whether the character set
is simple or complex:

   * If the character set does not need to use special string collating
     routines for sorting and does not need multi-byte character
     support, it is simple.

   * If the character set needs either of those features, it is complex.

For example, `greek' and `swe7' are simple character sets, whereas
`big5' and `czech' are complex character sets.

In the following instructions, MYSET represents the name of the
character set that you want to add.

  1. Add a `<charset>' element for MYSET to the
     `sql/share/charsets/Index.xml' file. Use the existing contents in
     the file as a guide to adding new contents.

     The `<charset>' element must list all the collations for the
     character set. These must include at least a binary collation and
     a default collation. The default collation is usually named using
     a suffix of `general_ci' (general, case insensitive). It is
     possible for the binary collation to be the default collation, but
     usually they are different. The default collation should have a
     `primary' flag. The binary collation should have a `binary' flag.

     You must assign a unique ID number to each collation. To find the
     maximum of the currently used collation IDs, use this query:

          SELECT MAX(ID) FROM INFORMATION_SCHEMA.COLLATIONS;

  2. This step depends on whether you are adding a simple or complex
     character set. A simple character set requires only a
     configuration file, whereas a complex character set requires C
     source file that defines collation functions, multi-byte
     functions, or both.

     For a simple character set, create a configuration file,
     `MYSET.xml', that describes the character set properties. Create
     this file in the `sql/share/charsets' directory. (You can use a
     copy of `latin1.xml' as the basis for this file.) The syntax for
     the file is very simple:

        * Comments are written as ordinary XML comments (`<!-- TEXT
          -->').

        * Words within `<map>' array elements are separated by
          arbitrary amounts of whitespace.

        * Each word within `<map>' array elements must be a number in
          hexadecimal format.

        * The `<map>' array element for the `<ctype>' element has 257
          words.  The other `<map>' array elements after that have 256
          words. See *Note character-arrays::.

        * For each collation listed in the `<charset>' element for the
          character set in `Index.xml', `MYSET.xml' must contain a
          `<collation>' element that defines the character ordering.

     For a complex character set, create a C source file that describes
     the character set properties and defines the support routines
     necessary to properly perform operations on the character set:

       1. Create the file `ctype-MYSET.c' in the `strings' directory.
          Look at one of the existing `ctype-*.c' files (such as
          `ctype-big5.c') to see what needs to be defined. The arrays
          in your file must have names like `ctype_MYSET',
          `to_lower_MYSET', and so on. These correspond to the arrays
          for a simple character set. See *Note character-arrays::.

       2. For each collation listed in the `<charset>' element for the
          character set in `Index.xml', the `ctype-MYSET.c' file must
          provide an implementation of the collation.

       3. If you need string collating functions, see *Note
          string-collating::.

       4. If you need multi-byte character support, see *Note
          multi-byte-characters::.

  3. Follow these steps to modify the configuration information.  Use
     the existing configuration information as a guide to adding
     information for MYSYS. The example here assumes that the character
     set has default and binary collations, but more lines will be
     needed if MYSET has additional collations.

       1. Edit `mysys/charset-def.c', and `register' the collations for
          the new character set.

          Add these lines to the `declaration' section:

               #ifdef HAVE_CHARSET_MYSET
               extern CHARSET_INFO my_charset_MYSET_general_ci;
               extern CHARSET_INFO my_charset_MYSET_bin;
               #endif

          Add these lines to the `registration' section:

               #ifdef HAVE_CHARSET_MYSET
                 add_compiled_collation(&my_charset_MYSET_general_ci);
                 add_compiled_collation(&my_charset_MYSET_bin);
               #endif

       2. If the character set uses `ctype-MYSET.c', edit
          `strings/Makefile.am' and add `ctype-MYSET.c' to each
          definition of the `CSRCS' variable, and to the `EXTRA_DIST'
          variable.

       3. If the character set uses `ctype-MYSET.c', edit
          `libmysql/Makefile.shared' and add `ctype-MYSET.lo' to the
          `mystringsobjects' definition.

       4. Edit `config/ac-macros/character_sets.m4':

            1. Add MYSET to one of the `define(CHARSETS_AVAILABLE...)'
               lines in alphabetic order.

            2. Add MYSET to `CHARSETS_COMPLEX'. This is needed even for
               simple character sets, or `configure' will not recognize
               `--default-character-set=MYSET'.

            3. Add MYSET to the first `case' control structure. Omit the
               `USE_MB' and `USE_MB_IDENT' lines for 8-bit character
               sets.

                    MYSET)
                      AC_DEFINE(HAVE_CHARSET_MYSET, 1, [Define to enable charset MYSET])
                      AC_DEFINE([USE_MB], 1, [Use multi-byte character routines])
                      AC_DEFINE(USE_MB_IDENT, 1)
                      ;;

            4. Add MYSET to the second `case' control structure:

                    MYSET)
                      default_charset_default_collation="MYSET_general_ci"
                      default_charset_collations="MYSET_general_ci MYSET_bin"
                      ;;

  4. Reconfigure, recompile, and test.


File: manual.info,  Node: character-arrays,  Next: string-collating,  Prev: adding-character-set,  Up: adding-character-set

9.4.1 The Character Definition Arrays
-------------------------------------

Each simple character set has a configuration file located in the
`sql/share/charsets' directory. The file is named `MYSET.xml'. It uses
`<map>' array elements to list character set properties. `<map>'
elements appear within these elements:

   * `<ctype>' defines attributes for each character

   * `<lower>' and `<upper>' list the lowercase and uppercase characters

   * `<unicode>' maps 8-bit character values to Unicode values

   * `<collation>' elements indicate character ordering for comparisons
     and sorts, one element per collation (binary collations need no
     `<map>' element because the character codes themselves provide the
     ordering)

For a complex character set as implemented in a `ctype-MYSET.c' file in
the `strings' directory, there are corresponding arrays:
`ctype_MYSET[]', `to_lower_MYSET[]', and so forth. Not every complex
character set has all of the arrays. See the existing `ctype-*.c' files
for examples. See the `CHARSET_INFO.txt' file in the `strings'
directory for additional information.

The `ctype' array is indexed by character value + 1 and has 257
elements. This is an old legacy convention for handling `EOF'. The
other arrays are indexed by character value and have 256 elements.

`ctype' array elements are bit values. Each element describes the
attributes of a single character in the character set. Each attribute
is associated with a bitmask, as defined in `include/m_ctype.h':

     #define _MY_U   01      /* Upper case */
     #define _MY_L   02      /* Lower case */
     #define _MY_NMR 04      /* Numeral (digit) */
     #define _MY_SPC 010     /* Spacing character */
     #define _MY_PNT 020     /* Punctuation */
     #define _MY_CTR 040     /* Control character */
     #define _MY_B   0100    /* Blank */
     #define _MY_X   0200    /* heXadecimal digit */

The `ctype' value for a given character should be the union of the
applicable bitmask values that describe the character. For example,
`'A'' is an uppercase character (`_MY_U') as well as a hexadecimal
digit (`_MY_X'), so its `ctype' value should be defined like this:

     ctype['A'+1] = _MY_U | _MY_X = 01 | 0200 = 0201

The bitmask values in `m_ctype.h' are octal values, but the elements of
the `ctype' array in `MYSET.xml' should be written as hexadecimal
values.

The `lower' and `upper' arrays hold the lowercase and uppercase
characters corresponding to each member of the character set. For
example:

     lower['A'] should contain 'a'
     upper['a'] should contain 'A'

Each `collation' array is a map indicating how characters should be
ordered for comparison and sorting purposes. MySQL sorts characters
based on the values of this information. In some cases, this is the
same as the `upper' array, which means that sorting is
case-insensitive. For more complicated sorting rules (for complex
character sets), see the discussion of string collating in *Note
string-collating::.


File: manual.info,  Node: string-collating,  Next: multi-byte-characters,  Prev: character-arrays,  Up: adding-character-set

9.4.2 String Collating Support
------------------------------

For simple character sets, sorting rules are specified in the
`MYSET.xml' configuration file using `<map>' array elements within
`<collation>' elements.  If the sorting rules for your language are too
complex to be handled with simple arrays, you need to define string
collating functions in the `ctype-MYSET.c' source file in the `strings'
directory.

The existing character sets provide the best documentation and examples
to show how these functions are implemented. Look at the `ctype-*.c'
files in the `strings' directory, such as the files for the `big5',
`czech', `gbk', `sjis', and `tis160' character sets. Take a look at the
`MY_COLLATION_HANDLER' structures to see how they are used, and see the
`CHARSET_INFO.txt' file in the `strings' directory for additional
information.


File: manual.info,  Node: multi-byte-characters,  Prev: string-collating,  Up: adding-character-set

9.4.3 Multi-Byte Character Support
----------------------------------

If you want to add support for a new character set that includes
multi-byte characters, you need to use multi-byte character functions
in the `ctype-MYSET.c' source file in the `strings' directory.

The existing character sets provide the best documentation and examples
to show how these functions are implemented. Look at the `ctype-*.c'
files in the `strings' directory, such as the files for the `euc_kr',
`gb2312', `gbk', `sjis', and `ujis' character sets. Take a look at the
`MY_CHARSET_HANDLER' structures to see how they are used, and see the
`CHARSET_INFO.txt' file in the `strings' directory for additional
information.


File: manual.info,  Node: adding-collation,  Next: problems-with-character-sets,  Prev: adding-character-set,  Up: internationalization-localization

9.5 How to Add a New Collation to a Character Set
=================================================

* Menu:

* charset-collation-implementations::  Collation Implementation Types
* adding-collation-choosing-id::  Choosing a Collation ID
* adding-collation-simple-8bit::  Adding a Simple Collation to an 8-Bit Character Set
* adding-collation-unicode-uca::  Adding a UCA Collation to a Unicode Character Set

A collation is a set of rules that defines how to compare and sort
character strings. Each collation in MySQL belongs to a single
character set. Every character set has at least one collation, and most
have two or more collations.

A collation orders characters based on weights. Each character in a
character set maps to a weight. Characters with equal weights compare
as equal, and characters with unequal weights compare according to the
relative magnitude of their weights.

MySQL supports several collation implementations, as discussed in *Note
charset-collation-implementations::. Some of these can be added to
MySQL without recompiling:

   * Simple collations for 8-bit character sets

   * UCA-based collations for Unicode character sets

   * Binary (`XXX_bin') collations

The following discussion describes how to add collations of the first
two types to existing character sets. All existing character sets
already have a binary collation, so there is no need here to describe
how to add one.

Summary of the procedure for adding a new collation:

  1. Choose a collation ID

  2. Add configuration information that names the collation and
     describes the character-ordering rules

  3. Restart the server

  4. Verify that the collation is present

The instructions here cover only collations that can be added without
recompiling MySQL. To add a collation that does require recompiling (as
implemented by means of functions in a C source file), use the
instructions in *Note adding-character-set::. However, instead of adding
all the information required for a complete character set, just modify
the appropriate files for an existing character set. That is, based on
what is already present for the character set's current collations, add
new data structures, functions, and configuration information for the
new collation. For an example, see the MySQL Blog article in the
following list of additional resources.

*Additional resources*

   * The Unicode Collation Algorithm (UCA) specification:
     `http://www.unicode.org/reports/tr10/'

   * The Locale Data Markup Language (LDML) specification:
     `http://www.unicode.org/reports/tr35/'

   * MySQL University session `How to Add a Collation':
     `http://forge.mysql.com/wiki/How_to_Add_a_Collation'

   * MySQL Blog article `Instructions for adding a new Unicode
     collation':
     `http://blogs.mysql.com/peterg/2008/05/19/instructions-for-adding-a-new-unicode-collation/'


File: manual.info,  Node: charset-collation-implementations,  Next: adding-collation-choosing-id,  Prev: adding-collation,  Up: adding-collation

9.5.1 Collation Implementation Types
------------------------------------

MySQL implements several types of collations:

*Simple collations for 8-bit character sets*

This kind of collation is implemented using an array of 256 weights
that defines a one-to-one mapping from character codes to weights.
`latin1_swedish_ci' is an example.  It is a case-insensitive collation,
so the uppercase and lowercase versions of a character have the same
weights and they compare as equal.

     mysql> SET NAMES 'latin1' COLLATE 'latin1_swedish_ci';
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT 'a' = 'A';
     +-----------+
     | 'a' = 'A' |
     +-----------+
     |         1 |
     +-----------+
     1 row in set (0.00 sec)

*Complex collations for 8-bit character sets*

This kind of collation is implemented using functions in a C source
file that define how to order characters, as described in *Note
adding-character-set::.

*Collations for non-Unicode multi-byte character sets*

For this type of collation, 8-bit (single-byte) and multi-byte
characters are handled differently. For 8-bit characters, character
codes map to weights in case-insensitive fashion. (For example, the
single-byte characters `'a'' and `'A'' both have a weight of `0x41'.)
For multi-byte characters, there are two types of relationship between
character codes and weights:

   * Weights equal character codes.  `sjis_japanese_ci' is an example
     of this kind of collation. The multi-byte character `'ぢ'' has a
     character code of `0x82C0', and the weight is also `0x82C0'.

   * Character codes map one-to-one to weights, but a code is not
     necessarily equal to the weight.  `gbk_chinese_ci' is an example
     of this kind of collation. The multi-byte character `'膰'' has a
     character code of `0x81B0' but a weight of `0xC286'.

*Collations for Unicode multi-byte character sets*

Some of these collations are based on the Unicode Collation Algorithm
(UCA), others are not.

Non-UCA collations have a one-to-one mapping from character code to
weight. In MySQL, such collations are case insensitive and accent
insensitive. `utf8_general_ci' is an example: `'a'', `'A'', `'A`'', and
`'a''' each have different character codes but all have a weight of
`0x0041' and compare as equal.

     mysql> SET NAMES 'utf8' COLLATE 'utf8_general_ci';
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT 'a' = 'A', 'a' = 'A`', 'a' = 'a'';
     +-----------+-----------+-----------+
     | 'a' = 'A' | 'a' = 'A`' | 'a' = 'a'' |
     +-----------+-----------+-----------+
     |         1 |         1 |         1 |
     +-----------+-----------+-----------+
     1 row in set (0.06 sec)

UCA-based collations in MySQL have these properties:

   * If a character has weights, each weight uses 2 bytes (16 bits)

   * A character may have zero weights (or an empty weight). In this
     case, the character is ignorable. Example: "U+0000 NULL" does not
     have a weight and is ignorable.

   * A character may have one weight. Example: `'a'' has a weight of
     `0x0E33'.

   * A character may have many weights. This is an expansion.  Example:
     The German letter `'ss'' (SZ LEAGUE, or SHARP S) has a weight of
     `0x0FEA0FEA'.

   * Many characters may have one weight. This is a contraction.
     Example: `'ch'' is a single letter in Czech and has a weight of
     `0x0EE2'.

A many-characters-to-many-weights mapping is also possible (this is
contraction with expansion), but is not supported by MySQL.

*Miscellaneous collations*

There are also a few collations that do not fall into any of the
previous categories.


File: manual.info,  Node: adding-collation-choosing-id,  Next: adding-collation-simple-8bit,  Prev: charset-collation-implementations,  Up: adding-collation

9.5.2 Choosing a Collation ID
-----------------------------

Each collation must have a unique ID. To add a new collation, you must
choose an ID value that is not currently used. The ID that you choose
is the value that will show up in these contexts:

   * The `Id' column of `SHOW COLLATION' output

   * The `ID' column of the `INFORMATION_SCHEMA.COLLATIONS' table

   * The `charsetnr' member of the `MYSQL_FIELD' C API data structure

   * The `number' member of the `MY_CHARSET_INFO' data structure
     returned by the *Note `mysql_get_character_set_info()':
     mysql-get-character-set-info.  C API function

To determine the largest currently used ID, issue the following
statement:

     mysql> SELECT MAX(ID) FROM INFORMATION_SCHEMA.COLLATIONS;
     +---------+
     | MAX(ID) |
     +---------+
     |     210 |
     +---------+

For the ouput just shown, you could choose an ID higher than 210 for
the new collation.

To display a list of all currently used IDs, issue this statement:

     mysql> SELECT ID FROM INFORMATION_SCHEMA.COLLATIONS ORDER BY ID;
     +-----+
     | ID  |
     +-----+
     |   1 |
     |   2 |
     | ... |
     |  52 |
     |  53 |
     |  57 |
     |  58 |
     | ... |
     |  98 |
     |  99 |
     | 128 |
     | 129 |
     | ... |
     | 210 |
     +-----+

In this case, you can either choose an unused ID from within the
current range of IDs, or choose an ID that is higher than the current
maximum ID. For example, in the output just shown, there are unused IDs
between 53 and 57, and between 99 and 128. Or you could choose an ID
higher than 210.

*Warning*:

If you upgrade MySQL, you may find that the collation ID you choose has
been assigned to a collation included in the new MySQL distribution. In
this case, you will need to choose a new value for your own collation.

In addition, before upgrading, you should save the configuration files
that you change. If you upgrade in place, the process will replace the
your modified files.


File: manual.info,  Node: adding-collation-simple-8bit,  Next: adding-collation-unicode-uca,  Prev: adding-collation-choosing-id,  Up: adding-collation

9.5.3 Adding a Simple Collation to an 8-Bit Character Set
---------------------------------------------------------

To add a simple collation for an 8-bit character set without
recompiling MySQL, use the following procedure. The example adds a
collation named `latin1_test_ci' to the `latin1' character set.

  1. Choose a collation ID, as shown in *Note
     adding-collation-choosing-id::. The following steps use an ID of
     56.

  2. You will need to modify the `Index.xml' and `latin1.xml'
     configuration files. These files will be located in the directory
     named by the `character_sets_dir' system variable. You can check
     the variable value as follows, although the pathname might be
     different on your system:

          mysql> SHOW VARIABLES LIKE 'character_sets_dir';
          +--------------------+-----------------------------------------+
          | Variable_name      | Value                                   |
          +--------------------+-----------------------------------------+
          | character_sets_dir | /user/local/mysql/share/mysql/charsets/ |
          +--------------------+-----------------------------------------+

  3. Choose a name for the collation and list it in the `Index.xml'
     file. Find the `<charset>' element for the character set to which
     the collation is being added, and add a `<collation>' element that
     indicates the collation name and ID. For example:

          <charset name="latin1">
            ...
            <!-- associate collation name with its ID -->
            <collation name="latin1_test_ci" id="56"/>
            ...
          </charset>

  4. In the `latin1.xml' configuration file, add a `<collation>'
     element that names the collation and that contains a `<map>'
     element that defines a character code-to-weight mapping table.
     Each word within the `<map>' element must be a number in
     hexadecimal format.

          <collation name="latin1_test_ci">
          <map>
           00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
           10 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1F
           20 21 22 23 24 25 26 27 28 29 2A 2B 2C 2D 2E 2F
           30 31 32 33 34 35 36 37 38 39 3A 3B 3C 3D 3E 3F
           40 41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E 4F
           50 51 52 53 54 55 56 57 58 59 5A 5B 5C 5D 5E 5F
           60 41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E 4F
           50 51 52 53 54 55 56 57 58 59 5A 7B 7C 7D 7E 7F
           80 81 82 83 84 85 86 87 88 89 8A 8B 8C 8D 8E 8F
           90 91 92 93 94 95 96 97 98 99 9A 9B 9C 9D 9E 9F
           A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 AA AB AC AD AE AF
           B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 BA BB BC BD BE BF
           41 41 41 41 5B 5D 5B 43 45 45 45 45 49 49 49 49
           44 4E 4F 4F 4F 4F 5C D7 5C 55 55 55 59 59 DE DF
           41 41 41 41 5B 5D 5B 43 45 45 45 45 49 49 49 49
           44 4E 4F 4F 4F 4F 5C F7 5C 55 55 55 59 59 DE FF
          </map>
          </collation>

  5. Restart the server and use this statement to verify that the
     collation is present:

          mysql> SHOW COLLATION LIKE 'latin1_test_ci';
          +----------------+---------+----+---------+----------+---------+
          | Collation      | Charset | Id | Default | Compiled | Sortlen |
          +----------------+---------+----+---------+----------+---------+
          | latin1_test_ci | latin1  | 56 |         |          |       1 |
          +----------------+---------+----+---------+----------+---------+


File: manual.info,  Node: adding-collation-unicode-uca,  Prev: adding-collation-simple-8bit,  Up: adding-collation

9.5.4 Adding a UCA Collation to a Unicode Character Set
-------------------------------------------------------

UCA collations for Unicode character serts can be added to MySQL
without recompiling by using a subset of the Locale Data Markup
Language (LDML), which is available at
`http://www.unicode.org/reports/tr35/'. In 5.1, this method of adding
collations is supported as of MySQL 5.1.20. With this method, you begin
with an existing `base' collation. Then you describe the new collation
in terms of how it differs from the base collation, rather than
defining the entire collation. The following table lists the base
collations for the Unicode character sets.

*Character Set*        *Base Collation*
`utf8'                 `utf8_unicode_ci'
`ucs2'                 `ucs2_unicode_ci'

The following brief summary describes the LDML characteristics required
for understanding the procedure for adding a collation given later in
this section:

   * LDML has reset rules and shift rules.

   * Characters named in these rules can be written in `\uNNNN' format,
     where NNNN is the hexadecimal Unicode code point value. Basic
     Latin letters `A-Z' and `a-z' can also be written literally (this
     is a MySQL limitation; the LDML specification allows literal
     non-Latin1 characters in the rules). Only characters in the Basic
     Multilingual Plane can be specified. This notation does not apply
     to characters outside the BMP range of `0000' to `FFFF'.

   * A reset rule does not specify any ordering in and of itself.
     Instead, it `resets' the ordering for subsequent shift rules to
     cause them to be taken in relation to a given character. Either of
     the following rules resets subsequent shift rules to be taken in
     relation to the letter `'A'':

          <reset>A</reset>

          <reset>\u0041</reset>

   * Shift rules define primary, secondary, and tertiary differences of
     a character from another character. They are specified using `<p>',
     `<s>', and `<t>' elements. Either of the following rules specifies
     a primary shift rule for the `'G'' character:

          <p>G</p>

          <p>\u0047</p>

   * Use primary differences to distinguish separate letters.

   * Use secondary differences to distiguish accent variations.

   * Use tertiary differences to distinguish lettercase variations.

To add a UCA collation for a Unicode character set without recompiling
MySQL, use the following procedure. The example adds a collation named
`utf8_phone_ci' to the `utf8' character set. The collation is designed
for a scenario involving a Web application for which users post their
names and phone numbers. Phone numbers can be given in very different
formats:

     +7-12345-67
     +7-12-345-67
     +7 12 345 67
     +7 (12) 345 67
     +71234567

The problem raised by dealing with these kinds of values is that the
varying allowable formats make searching for a specific phone number
very difficult. The solution is to define a new collation that reorders
punctuation characters, making them ignorable.

  1. Choose a collation ID, as shown in *Note
     adding-collation-choosing-id::. The following steps use an ID of
     252.

  2. You will need to modify the `Index.xml' configuration file. This
     file will be located in the directory named by the
     `character_sets_dir' system variable. You can check the variable
     value as follows, although the pathname might be different on your
     system:

          mysql> SHOW VARIABLES LIKE 'character_sets_dir';
          +--------------------+-----------------------------------------+
          | Variable_name      | Value                                   |
          +--------------------+-----------------------------------------+
          | character_sets_dir | /user/local/mysql/share/mysql/charsets/ |
          +--------------------+-----------------------------------------+

  3. Choose a name for the collation and list it in the `Index.xml'
     file. In addition, you'll need to provide the collation ordering
     rules. Find the `<charset>' element for the character set to which
     the collation is being added, and add a `<collation>' element that
     indicates the collation name and ID. Within the `<collation>'
     element, provide a `<rules>' element containing the ordering rules:

          <charset name="utf8">
            ...
            <!-- associate collation name with its ID -->
            <collation name="utf8_phone_ci" id="252">
              <rules>
                <reset>\u0000</reset>
                  <s>\u0020</s> <!-- space -->
                  <s>\u0028</s> <!-- left parenthesis -->
                  <s>\u0029</s> <!-- right parenthesis -->
                  <s>\u002B</s> <!-- plus -->
                  <s>\u002D</s> <!-- hyphen -->
              </rules>
            </collation>
            ...
          </charset>

  4. If you want a similar collation for other Unicode character sets,
     add other `<collation>' elements. For example, to define
     `ucs2_phone_ci', add a `<collation>' element to the `<charset
     name="ucs2">' element.  Remember that each collation must have its
     own unique ID.

  5. Restart the server and use this statement to verify that the
     collation is present:

          mysql> SHOW COLLATION LIKE 'utf8_phone_ci';
          +---------------+---------+-----+---------+----------+---------+
          | Collation     | Charset | Id  | Default | Compiled | Sortlen |
          +---------------+---------+-----+---------+----------+---------+
          | utf8_phone_ci | utf8    | 252 |         |          |       8 |
          +---------------+---------+-----+---------+----------+---------+

Now we can test the collation to make sure that it has the desired
properties.

Create a table containing some sample phone numbers using the new
collation:

     mysql> CREATE TABLE phonebook (
         ->   name VARCHAR(64),
         ->   phone VARCHAR(64) CHARACTER SET utf8 COLLATE utf8_phone_ci
         -> );
     Query OK, 0 rows affected (0.09 sec)

     mysql> INSERT INTO phonebook VALUES ('Svoj','+7 912 800 80 02');
     Query OK, 1 row affected (0.00 sec)

     mysql> INSERT INTO phonebook VALUES ('Hf','+7 (912) 800 80 04');
     Query OK, 1 row affected (0.00 sec)

     mysql> INSERT INTO phonebook VALUES ('Bar','+7-912-800-80-01');
     Query OK, 1 row affected (0.00 sec)

     mysql> INSERT INTO phonebook VALUES ('Ramil','(7912) 800 80 03');
     Query OK, 1 row affected (0.00 sec)

     mysql> INSERT INTO phonebook VALUES ('Sanja','+380 (912) 8008005');
     Query OK, 1 row affected (0.00 sec)

Run some queries to see whether the ignored punctuation characters are
in fact ignored for sorting and comparisons:

     mysql> SELECT * FROM phonebook ORDER BY phone;
     +-------+--------------------+
     | name  | phone              |
     +-------+--------------------+
     | Sanja | +380 (912) 8008005 |
     | Bar   | +7-912-800-80-01   |
     | Svoj  | +7 912 800 80 02   |
     | Ramil | (7912) 800 80 03   |
     | Hf    | +7 (912) 800 80 04 |
     +-------+--------------------+
     5 rows in set (0.00 sec)

     mysql> SELECT * FROM phonebook WHERE phone='+7(912)800-80-01';
     +------+------------------+
     | name | phone            |
     +------+------------------+
     | Bar  | +7-912-800-80-01 |
     +------+------------------+
     1 row in set (0.00 sec)

     mysql> SELECT * FROM phonebook WHERE phone='79128008001';
     +------+------------------+
     | name | phone            |
     +------+------------------+
     | Bar  | +7-912-800-80-01 |
     +------+------------------+
     1 row in set (0.00 sec)

     mysql> SELECT * FROM phonebook WHERE phone='7 9 1 2 8 0 0 8 0 0 1';
     +------+------------------+
     | name | phone            |
     +------+------------------+
     | Bar  | +7-912-800-80-01 |
     +------+------------------+
     1 row in set (0.00 sec)


File: manual.info,  Node: problems-with-character-sets,  Next: time-zone-support,  Prev: adding-collation,  Up: internationalization-localization

9.6 Problems With Character Sets
================================

If you try to use a character set that is not compiled into your
binary, you might run into the following problems:

   * Your program uses an incorrect path to determine where the
     character sets are stored (which is typically the
     `share/mysql/charsets' or `share/charsets' directory under the
     MySQL installation directory). This can be fixed by using the
     `--character-sets-dir' option when you run the program in
     question. For example, to specify a directory to be used by MySQL
     client programs, list it in the `[client]' group of your option
     file. The examples given here show what the setting might look
     like for Unix or Windows, respectively:

          [client]
          character-sets-dir=/usr/local/mysql/share/mysql/charsets

          [client]
          character-sets-dir="C:/Program Files/MySQL/MySQL Server 5.1/share/charsets"

   * The character set is a complex character set that cannot be loaded
     dynamically. In this case, you must recompile the program with
     support for the character set.

     For Unicode character sets, you can define collations without
     recompiling by using LDML notation. See *Note
     adding-collation-unicode-uca::.

   * The character set is a dynamic character set, but you do not have
     a configuration file for it. In this case, you should install the
     configuration file for the character set from a new MySQL
     distribution.

   * If your character set index file does not contain the name for the
     character set, your program displays an error message. The file is
     named `Index.xml' and the message is:

          Character set 'CHARSET_NAME' is not a compiled character set and is not
          specified in the '/usr/share/mysql/charsets/Index.xml' file

     To solve this problem, you should either get a new index file or
     manually add the name of any missing character sets to the current
     file.

For `MyISAM' tables, you can check the character set name and number
for a table with `myisamchk -dvv TBL_NAME'.


File: manual.info,  Node: time-zone-support,  Next: locale-support,  Prev: problems-with-character-sets,  Up: internationalization-localization

9.7 MySQL Server Time Zone Support
==================================

The MySQL server maintains several time zone settings:

   * The system time zone. When the server starts, it attempts to
     determine the time zone of the host machine and uses it to set the
     `system_time_zone' system variable. The value does not change
     thereafter.

     You can set the system time zone for MySQL Server at startup with
     the `--timezone=TIMEZONE_NAME' option to `mysqld_safe'. You can
     also set it by setting the `TZ' environment variable before you
     start `mysqld'. The allowable values for `--timezone' or `TZ' are
     system-dependent. Consult your operating system documentation to
     see what values are acceptable.

   * The server's current time zone. The global `time_zone' system
     variable indicates the time zone the server currently is operating
     in. The initial value for `time_zone' is `'SYSTEM'', which
     indicates that the server time zone is the same as the system time
     zone.

     The initial global server time zone value can be specified
     explicitly at startup with the `--default-time-zone=TIMEZONE'
     option on the command line, or you can use the following line in
     an option file:

          default-time-zone='TIMEZONE'

     If you have the `SUPER' privilege, you can set the global server
     time zone value at runtime with this statement:

          mysql> SET GLOBAL time_zone = TIMEZONE;

   * Per-connection time zones. Each client that connects has its own
     time zone setting, given by the session `time_zone' variable.
     Initially, the session variable takes its value from the global
     `time_zone' variable, but the client can change its own time zone
     with this statement:

          mysql> SET time_zone = TIMEZONE;

The current session time zone setting affects display and storage of
time values that are zone-sensitive. This includes the values displayed
by functions such as `NOW()' or `CURTIME()', and values stored in and
retrieved from `TIMESTAMP' columns. Values for `TIMESTAMP' columns are
converted from the current time zone to UTC for storage, and from UTC
to the current time zone for retrieval. The current time zone setting
does not affect values displayed by functions such as `UTC_TIMESTAMP()'
or values in `DATE', `TIME', or `DATETIME' columns.

The current values of the global and client-specific time zones can be
retrieved like this:

     mysql> SELECT @@global.time_zone, @@session.time_zone;

TIMEZONE values can be given in several formats, none of which are case
sensitive:

   * The value `'SYSTEM'' indicates that the time zone should be the
     same as the system time zone.

   * The value can be given as a string indicating an offset from UTC,
     such as `'+10:00'' or `'-6:00''.

   * The value can be given as a named time zone, such as
     `'Europe/Helsinki'', `'US/Eastern'', or `'MET''.  Named time zones
     can be used only if the time zone information tables in the
     `mysql' database have been created and populated.

The MySQL installation procedure creates the time zone tables in the
`mysql' database, but does not load them. You must do so manually using
the following instructions. (If you are upgrading to MySQL 4.1.3 or
later from an earlier version, you can create the tables by upgrading
your `mysql' database. Use the instructions in *Note mysql-upgrade::.
After creating the tables, you can load them.)

*Note*:

Loading the time zone information is not necessarily a one-time
operation because the information changes occasionally. For example,
the rules for Daylight Saving Time in the United States, Mexico, and
parts of Canada changed in 2007. When such changes occur, applications
that use the old rules become out of date and you may find it necessary
to reload the time zone tables to keep the information used by your
MySQL server current. See the notes at the end of this section.

If your system has its own _zoneinfo_ database (the set of files
describing time zones), you should use the `mysql_tzinfo_to_sql'
program for filling the time zone tables. Examples of such systems are
Linux, FreeBSD, Sun Solaris, and Mac OS X. One likely location for
these files is the `/usr/share/zoneinfo' directory. If your system does
not have a zoneinfo database, you can use the downloadable package
described later in this section.

The `mysql_tzinfo_to_sql' program is used to load the time zone tables.
On the command line, pass the zoneinfo directory pathname to
`mysql_tzinfo_to_sql' and send the output into the `mysql' program. For
example:

     shell> mysql_tzinfo_to_sql /usr/share/zoneinfo | mysql -u root mysql

`mysql_tzinfo_to_sql' reads your system's time zone files and generates
SQL statements from them.  `mysql' processes those statements to load
the time zone tables.

`mysql_tzinfo_to_sql' also can be used to load a single time zone file
or to generate leap second information:

   * To load a single time zone file TZ_FILE that corresponds to a time
     zone name TZ_NAME, invoke `mysql_tzinfo_to_sql' like this:

          shell> mysql_tzinfo_to_sql TZ_FILE TZ_NAME | mysql -u root mysql

     With this approach, you must execute a separate command to load
     the time zone file for each named zone that the server needs to
     know about.

   * If your time zone needs to account for leap seconds, initialize
     the leap second information like this, where TZ_FILE is the name
     of your time zone file:

          shell> mysql_tzinfo_to_sql --leap TZ_FILE | mysql -u root mysql

   * After running `mysql_tzinfo_to_sql', it is best to restart the
     server so that it does not continue to use any previously cached
     time zone data.

If your system is one that has no zoneinfo database (for example,
Windows or HP-UX), you can use the package of pre-built time zone
tables that is available for download at the MySQL Developer Zone:

     `http://dev.mysql.com/downloads/timezones.html'

This time zone package contains `.frm', `.MYD', and `.MYI' files for
the `MyISAM' time zone tables. These tables should be part of the
`mysql' database, so you should place the files in the `mysql'
subdirectory of your MySQL server's data directory. The server should
be stopped while you do this and restarted afterward.

*Warning*:

Do not use the downloadable package if your system has a zoneinfo
database. Use the `mysql_tzinfo_to_sql' utility instead.  Otherwise,
you may cause a difference in datetime handling between MySQL and other
applications on your system.

For information about time zone settings in replication setup, please
see *Note replication-features::.

*Staying Current with Time Zone Changes*

As mentioned earlier, when the time zone rules change, applications
that use the old rules become out of date. To stay current, it is
necessary to make sure that your system uses current time zone
information is used. For MySQL, there are two factors to consider in
staying current:

   * The operating system time affects the value that the MySQL server
     uses for times if its time zone is set to `SYSTEM'. Make sure that
     your operating system is using the latest time zone information.
     For most operating systems, the latest update or service pack
     prepares your system for the time changes. Check the Web site for
     your operating system vendor for an update that addresses the time
     changes.

   * If you replace the system's `/etc/localtime' timezone file with a
     version that uses rules differing from those in effect at `mysqld'
     startup, you should restart `mysqld' so that it uses the updated
     rules.  Otherwise, `mysqld' might not notice when the system
     changes its time.

   * If you use named time zones with MySQL, make sure that the time
     zone tables in the `mysql' database are up to date. If your system
     has its own zoneinfo database, you should reload the MySQL time
     zone tables whenever the zoneinfo database is updated, using the
     instructions given earlier in this section. For systems that do
     not have their own zoneinfo database, check the MySQL Developer
     Zone for updates. When a new update is available, download it and
     use it to replace your current time zone tables. `mysqld' caches
     time zone information that it looks up, so after replacing the
     time zone tables, you should restart `mysqld' to make sure that it
     does not continue to serve outdated time zone data.

If you are uncertain whether named time zones are available, for use
either as the server's time zone setting or by clients that set their
own time zone, check whether your time zone tables are empty. The
following query determines whether the table that contains time zone
names has any rows:

     mysql> SELECT COUNT(*) FROM mysql.time_zone_name;
     +----------+
     | COUNT(*) |
     +----------+
     |        0 |
     +----------+

A count of zero indicates that the table is empty. In this case, no one
can be using named time zones, and you don't need to update the tables.
A count greater than zero indicates that the table is not empty and
that its contents are available to be used for named time zone support.
In this case, you should be sure to reload your time zone tables so
that anyone who uses named time zones will get correct query results.

To check whether your MySQL installation is updated properly for a
change in Daylight Saving Time rules, use a test like the one
following. The example uses values that are appropriate for the 2007
DST 1-hour change that occurs in the United States on March 11 at 2 a.m.

The test uses these two queries:

     SELECT CONVERT_TZ('2007-03-11 2:00:00','US/Eastern','US/Central');
     SELECT CONVERT_TZ('2007-03-11 3:00:00','US/Eastern','US/Central');

The two time values indicate the times at which the DST change occurs,
and the use of named time zones requires that the time zone tables be
used. The desired result is that both queries return the same result
(the input time, converted to the equivalent value in the 'US/Central'
time zone).

Before updating the time zone tables, you would see an incorrect result
like this:

     mysql> SELECT CONVERT_TZ('2007-03-11 2:00:00','US/Eastern','US/Central');
     +------------------------------------------------------------+
     | CONVERT_TZ('2007-03-11 2:00:00','US/Eastern','US/Central') |
     +------------------------------------------------------------+
     | 2007-03-11 01:00:00                                        |
     +------------------------------------------------------------+

     mysql> SELECT CONVERT_TZ('2007-03-11 3:00:00','US/Eastern','US/Central');
     +------------------------------------------------------------+
     | CONVERT_TZ('2007-03-11 3:00:00','US/Eastern','US/Central') |
     +------------------------------------------------------------+
     | 2007-03-11 02:00:00                                        |
     +------------------------------------------------------------+

After updating the tables, you should see the correct result:

     mysql> SELECT CONVERT_TZ('2007-03-11 2:00:00','US/Eastern','US/Central');
     +------------------------------------------------------------+
     | CONVERT_TZ('2007-03-11 2:00:00','US/Eastern','US/Central') |
     +------------------------------------------------------------+
     | 2007-03-11 01:00:00                                        |
     +------------------------------------------------------------+

     mysql> SELECT CONVERT_TZ('2007-03-11 3:00:00','US/Eastern','US/Central');
     +------------------------------------------------------------+
     | CONVERT_TZ('2007-03-11 3:00:00','US/Eastern','US/Central') |
     +------------------------------------------------------------+
     | 2007-03-11 01:00:00                                        |
     +------------------------------------------------------------+


File: manual.info,  Node: locale-support,  Prev: time-zone-support,  Up: internationalization-localization

9.8 MySQL Server Locale Support
===============================

Beginning with MySQL 5.1.12, the locale indicated by the
`lc_time_names' system variable controls the language used to display
day and month names and abbreviations.  This variable affects the
output from the `DATE_FORMAT()', `DAYNAME()' and `MONTHNAME()'
functions.

Locale names are POSIX-style values such as `'ja_JP'' or `'pt_BR''. The
default value is `'en_US'' regardless of your system's locale setting,
but you can set the value at server startup or set the `GLOBAL' value
if you have the `SUPER' privilge. Any client can examine the value of
`lc_time_names' or set its `SESSION' value to affect the locale for its
own connection.

     mysql> SET NAMES 'utf8';
     Query OK, 0 rows affected (0.09 sec)

     mysql> SELECT @@lc_time_names;
     +-----------------+
     | @@lc_time_names |
     +-----------------+
     | en_US           |
     +-----------------+
     1 row in set (0.00 sec)

     mysql> SELECT DAYNAME('2010-01-01'), MONTHNAME('2010-01-01');
     +-----------------------+-------------------------+
     | DAYNAME('2010-01-01') | MONTHNAME('2010-01-01') |
     +-----------------------+-------------------------+
     | Friday                | January                 |
     +-----------------------+-------------------------+
     1 row in set (0.00 sec)

     mysql> SELECT DATE_FORMAT('2010-01-01','%W %a %M %b');
     +-----------------------------------------+
     | DATE_FORMAT('2010-01-01','%W %a %M %b') |
     +-----------------------------------------+
     | Friday Fri January Jan                  |
     +-----------------------------------------+
     1 row in set (0.00 sec)

     mysql> SET lc_time_names = 'es_MX';
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT @@lc_time_names;
     +-----------------+
     | @@lc_time_names |
     +-----------------+
     | es_MX           |
     +-----------------+
     1 row in set (0.00 sec)

     mysql> SELECT DAYNAME('2010-01-01'), MONTHNAME('2010-01-01');
     +-----------------------+-------------------------+
     | DAYNAME('2010-01-01') | MONTHNAME('2010-01-01') |
     +-----------------------+-------------------------+
     | viernes               | enero                   |
     +-----------------------+-------------------------+
     1 row in set (0.00 sec)

     mysql> SELECT DATE_FORMAT('2010-01-01','%W %a %M %b');
     +-----------------------------------------+
     | DATE_FORMAT('2010-01-01','%W %a %M %b') |
     +-----------------------------------------+
     | viernes vie enero ene                   |
     +-----------------------------------------+
     1 row in set (0.00 sec)

The day or month name for each of the affected functions is converted
from `utf8' to the character set indicated by the
`character_set_connection' system variable.

`lc_time_names' may be set to any of the following locale values:

`ar_AE': Arabic - United Arab        `ar_BH': Arabic - Bahrain
Emirates                             
`ar_DZ': Arabic - Algeria            `ar_EG': Arabic - Egypt
`ar_IN': Arabic - Iran               `ar_IQ': Arabic - Iraq
`ar_JO': Arabic - Jordan             `ar_KW': Arabic - Kuwait
`ar_LB': Arabic - Lebanon            `ar_LY': Arabic - Libya
`ar_MA': Arabic - Morocco            `ar_OM': Arabic - Oman
`ar_QA': Arabic - Qatar              `ar_SA': Arabic - Saudi Arabia
`ar_SD': Arabic - Sudan              `ar_SY': Arabic - Syria
`ar_TN': Arabic - Tunisia            `ar_YE': Arabic - Yemen
`be_BY': Belarusian - Belarus        `bg_BG': Bulgarian - Bulgaria
`ca_ES': Catalan - Catalan           `cs_CZ': Czech - Czech Republic
`da_DK': Danish - Denmark            `de_AT': German - Austria
`de_BE': German - Belgium            `de_CH': German - Switzerland
`de_DE': German - Germany            `de_LU': German - Luxembourg
`EE': Estonian - Estonia             `en_AU': English - Australia
`en_CA': English - Canada            `en_GB': English - United Kingdom
`en_IN': English - India             `en_NZ': English - New Zealand
`en_PH': English - Philippines       `en_US': English - United States
`en_ZA': English - South Africa      `en_ZW': English - Zimbabwe
`es_AR': Spanish - Argentina         `es_BO': Spanish - Bolivia
`es_CL': Spanish - Chile             `es_CO': Spanish - Columbia
`es_CR': Spanish - Costa Rica        `es_DO': Spanish - Dominican
                                     Republic
`es_EC': Spanish - Ecuador           `es_ES': Spanish - Spain
`es_GT': Spanish - Guatemala         `es_HN': Spanish - Honduras
`es_MX': Spanish - Mexico            `es_NI': Spanish - Nicaragua
`es_PA': Spanish - Panama            `es_PE': Spanish - Peru
`es_PR': Spanish - Puerto Rico       `es_PY': Spanish - Paraguay
`es_SV': Spanish - El Salvador       `es_US': Spanish - United States
`es_UY': Spanish - Uruguay           `es_VE': Spanish - Venezuela
`eu_ES': Basque - Basque             `fi_FI': Finnish - Finland
`fo_FO': Faroese - Faroe Islands     `fr_BE': French - Belgium
`fr_CA': French - Canada             `fr_CH': French - Switzerland
`fr_FR': French - France             `fr_LU': French - Luxembourg
`gl_ES': Galician - Galician         `gu_IN': Gujarati - India
`he_IL': Hebrew - Israel             `hi_IN': Hindi - India
`hr_HR': Croatian - Croatia          `hu_HU': Hungarian - Hungary
`id_ID': Indonesian - Indonesia      `is_IS': Icelandic - Iceland
`it_CH': Italian - Switzerland       `it_IT': Italian - Italy
`ja_JP': Japanese - Japan            `ko_KR': Korean - Korea
`lt_LT': Lithuanian - Lithuania      `lv_LV': Latvian - Latvia
`mk_MK': Macedonian - FYROM          `mn_MN': Mongolia - Mongolian
`ms_MY': Malay - Malaysia            `nb_NO': Norwegian(Bokml) - Norway
`nl_BE': Dutch - Belgium             `nl_NL': Dutch - The Netherlands
`no_NO': Norwegian - Norway          `pl_PL': Polish - Poland
`pt_BR': Portugese - Brazil          `pt_PT': Portugese - Portugal
`ro_RO': Romanian - Romania          `ru_RU': Russian - Russia
`ru_UA': Russian - Ukraine           `sk_SK': Slovak - Slovakia
`sl_SI': Slovenian - Slovenia        `sq_AL': Albanian - Albania
`sr_YU': Serbian - Yugoslavia        `sv_FI': Swedish - Finland
`sv_SE': Swedish - Sweden            `ta_IN': Tamil - India
`te_IN': Telugu - India              `th_TH': Thai - Thailand
`tr_TR': Turkish - Turkey            `uk_UA': Ukrainian - Ukraine
`ur_PK': Urdu - Pakistan             `vi_VN': Vietnamese - Vietnam
`zh_CN': Chinese - Peoples Republic  `zh_HK': Chinese - Hong Kong SAR
of China                             
`zh_TW': Chinese - Taiwan            

`lc_time_names' currently does not affect the `STR_TO_DATE()' or
`GET_FORMAT()' function.


File: manual.info,  Node: data-types,  Next: functions,  Prev: internationalization-localization,  Up: Top

10 Data Types
*************

* Menu:

* data-type-overview::           Data Type Overview
* numeric-types::                Numeric Types
* date-and-time-types::          Date and Time Types
* string-types::                 String Types
* storage-requirements::         Data Type Storage Requirements
* choosing-types::               Choosing the Right Type for a Column
* other-vendor-data-types::      Using Data Types from Other Database Engines

MySQL supports a number of data types in several categories: numeric
types, date and time types, and string (character) types. This chapter
first gives an overview of these data types, and then provides a more
detailed description of the properties of the types in each category,
and a summary of the data type storage requirements. The initial
overview is intentionally brief. The more detailed descriptions later
in the chapter should be consulted for additional information about
particular data types, such as the allowable formats in which you can
specify values.

MySQL also supports extensions for handing spatial data.  *Note
spatial-extensions::, provides information about these data types.

Data type descriptions use these conventions:

   * M indicates the maximum display width for integer types. For
     floating-point and fixed-point types, M is the total number of
     digits that can be stored. For string types, M is the maximum
     length. The maximum allowable value of M depends on the data type.

   * D applies to floating-point and fixed-point types and indicates
     the number of digits following the decimal point. The maximum
     possible value is 30, but should be no greater than M-2.

   * Square brackets (``['' and ``]'') indicate optional parts of type
     definitions.


File: manual.info,  Node: data-type-overview,  Next: numeric-types,  Prev: data-types,  Up: data-types

10.1 Data Type Overview
=======================

* Menu:

* numeric-type-overview::        Overview of Numeric Types
* date-and-time-type-overview::  Overview of Date and Time Types
* string-type-overview::         Overview of String Types
* data-type-defaults::           Data Type Default Values


File: manual.info,  Node: numeric-type-overview,  Next: date-and-time-type-overview,  Prev: data-type-overview,  Up: data-type-overview

10.1.1 Overview of Numeric Types
--------------------------------

A summary of the numeric data types follows. For additional
information, see *Note numeric-types::. Storage requirements are given
in *Note storage-requirements::.

M indicates the maximum display width for integer types. The maximum
legal display width is 255.  Display width is unrelated to the range of
values a type can contain, as described in *Note numeric-types::. For
floating-point and fixed-point types, M is the total number of digits
that can be stored.

If you specify `ZEROFILL' for a numeric column, MySQL automatically
adds the `UNSIGNED' attribute to the column.

Numeric data types that allow the `UNSIGNED' attribute also allow
`SIGNED'. However, these data types are signed by default, so the
`SIGNED' attribute has no effect.

`SERIAL' is an alias for `BIGINT UNSIGNED NOT NULL AUTO_INCREMENT
UNIQUE'.

`SERIAL DEFAULT VALUE' in the definition of an integer column is an
alias for `NOT NULL AUTO_INCREMENT UNIQUE'.

*Warning*:

When you use subtraction between integer values where one is of type
`UNSIGNED', the result is unsigned unless the `NO_UNSIGNED_SUBTRACTION'
SQL mode is enabled. See *Note cast-functions::.

   * `BIT[(M)]'

     A bit-field type. M indicates the number of bits per value, from 1
     to 64. The default is 1 if M is omitted.

   * `TINYINT[(M)] [UNSIGNED] [ZEROFILL]'

     A very small integer. The signed range is `-128' to `127'. The
     unsigned range is `0' to `255'.

   * `BOOL', `BOOLEAN'

     These types are synonyms for `TINYINT(1)'.  A value of zero is
     considered false. Non-zero values are considered true:

          mysql> SELECT IF(0, 'true', 'false');
          +------------------------+
          | IF(0, 'true', 'false') |
          +------------------------+
          | false                  |
          +------------------------+

          mysql> SELECT IF(1, 'true', 'false');
          +------------------------+
          | IF(1, 'true', 'false') |
          +------------------------+
          | true                   |
          +------------------------+

          mysql> SELECT IF(2, 'true', 'false');
          +------------------------+
          | IF(2, 'true', 'false') |
          +------------------------+
          | true                   |
          +------------------------+

     However, the values `TRUE' and `FALSE' are merely aliases for `1'
     and `0', respectively, as shown here:

          mysql> SELECT IF(0 = FALSE, 'true', 'false');
          +--------------------------------+
          | IF(0 = FALSE, 'true', 'false') |
          +--------------------------------+
          | true                           |
          +--------------------------------+

          mysql> SELECT IF(1 = TRUE, 'true', 'false');
          +-------------------------------+
          | IF(1 = TRUE, 'true', 'false') |
          +-------------------------------+
          | true                          |
          +-------------------------------+

          mysql> SELECT IF(2 = TRUE, 'true', 'false');
          +-------------------------------+
          | IF(2 = TRUE, 'true', 'false') |
          +-------------------------------+
          | false                         |
          +-------------------------------+

          mysql> SELECT IF(2 = FALSE, 'true', 'false');
          +--------------------------------+
          | IF(2 = FALSE, 'true', 'false') |
          +--------------------------------+
          | false                          |
          +--------------------------------+

     The last two statements display the results shown because `2' is
     equal to neither `1' nor `0'.

     We intend to implement full boolean type handling, in accordance
     with standard SQL, in a future MySQL release.

   * `SMALLINT[(M)] [UNSIGNED] [ZEROFILL]'

     A small integer. The signed range is `-32768' to `32767'. The
     unsigned range is `0' to `65535'.

   * `MEDIUMINT[(M)] [UNSIGNED] [ZEROFILL]'

     A medium-sized integer. The signed range is `-8388608' to
     `8388607'.  The unsigned range is `0' to `16777215'.

   * `INT[(M)] [UNSIGNED] [ZEROFILL]'

     A normal-size integer. The signed range is `-2147483648' to
     `2147483647'. The unsigned range is `0' to `4294967295'.

   * `INTEGER[(M)] [UNSIGNED] [ZEROFILL]'

     This type is a synonym for `INT'.

   * `BIGINT[(M)] [UNSIGNED] [ZEROFILL]'

     A large integer. The signed range is `-9223372036854775808' to
     `9223372036854775807'. The unsigned range is `0' to
     `18446744073709551615'.

     `SERIAL' is an alias for `BIGINT UNSIGNED NOT NULL AUTO_INCREMENT
     UNIQUE'.

     Some things you should be aware of with respect to `BIGINT'
     columns:

        * All arithmetic is done using signed `BIGINT' or `DOUBLE'
          values, so you should not use unsigned big integers larger
          than `9223372036854775807' (63 bits) except with bit
          functions! If you do that, some of the last digits in the
          result may be wrong because of rounding errors when
          converting a `BIGINT' value to a `DOUBLE'.

          MySQL can handle `BIGINT' in the following cases:

             * When using integers to store large unsigned values in a
               `BIGINT' column.

             * In `MIN(COL_NAME)' or `MAX(COL_NAME)', where COL_NAME
               refers to a `BIGINT' column.

             * When using operators (`+', `-', `*', and so on) where
               both operands are integers.

        * You can always store an exact integer value in a `BIGINT'
          column by storing it using a string. In this case, MySQL
          performs a string-to-number conversion that involves no
          intermediate double-precision representation.

        * The `-', `+', and `*' operators use `BIGINT' arithmetic when
          both operands are integer values. This means that if you
          multiply two big integers (or results from functions that
          return integers), you may get unexpected results when the
          result is larger than `9223372036854775807'.

   * `FLOAT[(M,D)] [UNSIGNED] [ZEROFILL]'

     A small (single-precision) floating-point number. Allowable values
     are `-3.402823466E+38' to `-1.175494351E-38', `0', and
     `1.175494351E-38' to `3.402823466E+38'. These are the theoretical
     limits, based on the IEEE standard. The actual range might be
     slightly smaller depending on your hardware or operating system.

     M is the total number of digits and D is the number of digits
     following the decimal point. If M and D are omitted, values are
     stored to the limits allowed by the hardware. A single-precision
     floating-point number is accurate to approximately 7 decimal
     places.

     `UNSIGNED', if specified, disallows negative values.

     Using `FLOAT' might give you some unexpected problems because all
     calculations in MySQL are done with double precision. See *Note
     no-matching-rows::.

   * `DOUBLE[(M,D)] [UNSIGNED] [ZEROFILL]'

     A normal-size (double-precision) floating-point number.  Allowable
     values are `-1.7976931348623157E+308' to
     `-2.2250738585072014E-308', `0', and `2.2250738585072014E-308' to
     `1.7976931348623157E+308'. These are the theoretical limits, based
     on the IEEE standard. The actual range might be slightly smaller
     depending on your hardware or operating system.

     M is the total number of digits and D is the number of digits
     following the decimal point. If M and D are omitted, values are
     stored to the limits allowed by the hardware. A double-precision
     floating-point number is accurate to approximately 15 decimal
     places.

     `UNSIGNED', if specified, disallows negative values.

   * `DOUBLE PRECISION[(M,D)] [UNSIGNED] [ZEROFILL]', `REAL[(M,D)]
     [UNSIGNED] [ZEROFILL]'

     These types are synonyms for `DOUBLE'.  Exception: If the
     `REAL_AS_FLOAT' SQL mode is enabled, `REAL' is a synonym for
     `FLOAT' rather than `DOUBLE'.

   * `FLOAT(P) [UNSIGNED] [ZEROFILL]'

     A floating-point number. P represents the precision in bits, but
     MySQL uses this value only to determine whether to use `FLOAT' or
     `DOUBLE' for the resulting data type. If P is from 0 to 24, the
     data type becomes `FLOAT' with no M or D values. If P is from 25
     to 53, the data type becomes `DOUBLE' with no M or D values. The
     range of the resulting column is the same as for the
     single-precision `FLOAT' or double-precision `DOUBLE' data types
     described earlier in this section.

     `FLOAT(P)' syntax is provided for ODBC compatibility.

   * `DECIMAL[(M[,D])] [UNSIGNED] [ZEROFILL]'

     A packed `exact' fixed-point number.  M is the total number of
     digits (the precision) and D is the number of digits after the
     decimal point (the scale). The decimal point and (for negative
     numbers) the ``-'' sign are not counted in M. If D is 0, values
     have no decimal point or fractional part. The maximum number of
     digits (M) for `DECIMAL' is 65. The maximum number of supported
     decimals (D) is 30. If D is omitted, the default is 0.  If M is
     omitted, the default is 10.

     `UNSIGNED', if specified, disallows negative values.

     All basic calculations (`+, -, *, /') with `DECIMAL' columns are
     done with a precision of 65 digits.

   * `DEC[(M[,D])] [UNSIGNED] [ZEROFILL]', `NUMERIC[(M[,D])] [UNSIGNED]
     [ZEROFILL]', `FIXED[(M[,D])] [UNSIGNED] [ZEROFILL]'

     These types are synonyms for `DECIMAL'. The `FIXED' synonym is
     available for compatibility with other database systems.


File: manual.info,  Node: date-and-time-type-overview,  Next: string-type-overview,  Prev: numeric-type-overview,  Up: data-type-overview

10.1.2 Overview of Date and Time Types
--------------------------------------

A summary of the temporal data types follows. For additional
information, see *Note date-and-time-types::. Storage requirements are
given in *Note storage-requirements::. Functions that operate on
temporal values are described at *Note date-and-time-functions::.

For the `DATETIME' and `DATE' range descriptions, `supported' means
that although earlier values might work, there is no guarantee.

   * `DATE'

     A date. The supported range is `'1000-01-01'' to `'9999-12-31''.
     MySQL displays `DATE' values in `'YYYY-MM-DD'' format, but allows
     assignment of values to `DATE' columns using either strings or
     numbers.

   * `DATETIME'

     A date and time combination. The supported range is `'1000-01-01
     00:00:00'' to `'9999-12-31 23:59:59''. MySQL displays `DATETIME'
     values in `'YYYY-MM-DD HH:MM:SS'' format, but allows assignment of
     values to `DATETIME' columns using either strings or numbers.

   * `TIMESTAMP'

     A timestamp. The range is `'1970-01-01 00:00:01'' UTC to
     `'2038-01-09 03:14:07'' UTC. `TIMESTAMP' values are stored as the
     number of seconds since the epoch (`'1970-01-01 00:00:00'' UTC). A
     `TIMESTAMP' cannot represent the value `'1970-01-01 00:00:00''
     because that is equivalent to 0 seconds from the epoch and the
     value 0 is reserved for representing `'0000-00-00 00:00:00'', the
     `zero' `TIMESTAMP' value.

     A `TIMESTAMP' column is useful for recording the date and time of
     an `INSERT' or `UPDATE' operation. By default, the first
     `TIMESTAMP' column in a table is automatically set to the date and
     time of the most recent operation if you do not assign it a value
     yourself. You can also set any `TIMESTAMP' column to the current
     date and time by assigning it a `NULL' value. Variations on
     automatic initialization and update properties are described in
     *Note timestamp::.

     A `TIMESTAMP' value is returned as a string in the format
     `'YYYY-MM-DD HH:MM:SS'' with a display width fixed at 19
     characters. To obtain the value as a number, you should add `+0'
     to the timestamp column.

     *Note*:

     The `TIMESTAMP' format that was used prior to MySQL 4.1 is not
     supported in MySQL 5.1; see `MySQL 3.23, 4.0, 4.1 Reference
     Manual' for information regarding the old format.

   * `TIME'

     A time. The range is `'-838:59:59'' to `'838:59:59''. MySQL
     displays `TIME' values in `'HH:MM:SS'' format, but allows
     assignment of values to `TIME' columns using either strings or
     numbers.

   * `YEAR[(2|4)]'

     A year in two-digit or four-digit format. The default is
     four-digit format. In four-digit format, the allowable values are
     `1901' to `2155', and `0000'. In two-digit format, the allowable
     values are `70' to `69', representing years from 1970 to 2069.
     MySQL displays `YEAR' values in `YYYY' format, but allows you to
     assign values to `YEAR' columns using either strings or numbers.

The `SUM()' and `AVG()' aggregate functions do not work with temporal
values. (They convert the values to numbers, which loses the part after
the first non-numeric character.) To work around this problem, you can
convert to numeric units, perform the aggregate operation, and convert
back to a temporal value. Examples:

     SELECT SEC_TO_TIME(SUM(TIME_TO_SEC(TIME_COL))) FROM TBL_NAME;
     SELECT FROM_DAYS(SUM(TO_DAYS(DATE_COL))) FROM TBL_NAME;


File: manual.info,  Node: string-type-overview,  Next: data-type-defaults,  Prev: date-and-time-type-overview,  Up: data-type-overview

10.1.3 Overview of String Types
-------------------------------

A summary of the string data types follows. For additional information,
see *Note string-types::. Storage requirements are given in *Note
storage-requirements::.

In some cases, MySQL may change a string column to a type different
from that given in a `CREATE TABLE' or `ALTER TABLE' statement. See
*Note silent-column-changes::.

MySQL interprets length specifications in character column definitions
in character units. This applies to `CHAR', `VARCHAR', and the `TEXT'
types.

Column definitions for many string data types can include attributes
that specify the character set or collation of the column. These
attributes apply to the `CHAR', `VARCHAR', the `TEXT' types, `ENUM',
and `SET' data types:

   * The `CHARACTER SET' attribute specifies the character set, and the
     `COLLATE' attribute specifies a collation for the character set.
     For example:

          CREATE TABLE t
          (
              c1 VARCHAR(20) CHARACTER SET utf8,
              c2 TEXT CHARACTER SET latin1 COLLATE latin1_general_cs
          );

     This table definition creates a column named `c1' that has a
     character set of `utf8' with the default collation for that
     character set, and a column named `c2' that has a character set of
     `latin1' and a case-sensitive collation.

     `CHARSET' is a synonym for `CHARACTER SET'.

   * Specifying the `CHARACTER SET binary' attribute for a character
     data type causes the column to be created as the corresponding
     binary data type: `CHAR' becomes `BINARY', `VARCHAR' becomes
     `VARBINARY', and `TEXT' becomes `BLOB'. For the `ENUM' and `SET'
     data types, this does not occur; they are created as declared.
     Suppose that you specify a table using this definition:

          CREATE TABLE t
          (
            c1 VARCHAR(10) CHARACTER SET binary,
            c2 TEXT CHARACTER SET binary,
            c3 ENUM('a','b','c') CHARACTER SET binary
          );

     The resulting table has this definition:

          CREATE TABLE t
          (
            c1 VARBINARY(10),
            c2 BLOB,
            c3 ENUM('a','b','c') CHARACTER SET binary
          );

   * The `ASCII' attribute is shorthand for `CHARACTER SET latin1'.

   * The `UNICODE' attribute is shorthand for `CHARACTER SET ucs2'.

   * The `BINARY' attribute is shorthand for specifying the binary
     collation of the column character set.  In this case, sorting and
     comparison are based on numeric character values.

Character column sorting and comparison are based on the character set
assigned to the column. For the `CHAR', `VARCHAR', `TEXT', `ENUM', and
`SET' data types, you can declare a column with a binary collation or
the `BINARY' attribute to cause sorting and comparison to use the
underlying character code values rather than a lexical ordering.

*Note charset::, provides additional information about use of character
sets in MySQL.

   * `[NATIONAL] CHAR[(M)] [CHARACTER SET CHARSET_NAME] [COLLATE
     COLLATION_NAME]'

     A fixed-length string that is always right-padded with spaces to
     the specified length when stored.  M represents the column length
     in characters. The range of M is 0 to 255. If M is omitted, the
     length is 1.

     *Note*:

     Trailing spaces are removed when `CHAR' values are retrieved
     unless the `PAD_CHAR_TO_FULL_LENGTH' SQL mode is enabled.

     `CHAR' is shorthand for `CHARACTER'. `NATIONAL CHAR' (or its
     equivalent short form, `NCHAR') is the standard SQL way to define
     that a `CHAR' column should use some predefined character set.
     MySQL 4.1 and up uses `utf8' as this predefined character set.
     *Note charset-national::.

     The `CHAR BYTE' data type is an alias for the `BINARY' data type.
     This is a compatibility feature.

     MySQL allows you to create a column of type `CHAR(0)'. This is
     useful primarily when you have to be compliant with old
     applications that depend on the existence of a column but that do
     not actually use its value. `CHAR(0)' is also quite nice when you
     need a column that can take only two values: A column that is
     defined as `CHAR(0) NULL' occupies only one bit and can take only
     the values `NULL' and `''' (the empty string).

   * `[NATIONAL] VARCHAR(M) [CHARACTER SET CHARSET_NAME] [COLLATE
     COLLATION_NAME]'

     A variable-length string. M represents the maximum column length
     in characters. The range of M is 0 to 65,535. The effective
     maximum length of a `VARCHAR' is subject to the maximum row size
     (65,535 bytes, which is shared among all columns) and the
     character set used. For example, `utf8' characters can require up
     to three bytes per character, so a `VARCHAR' column that uses the
     `utf8' character set can be declared to be a maximum of 21,844
     characters.

     MySQL stores `VARCHAR' values as a one-byte or two-byte length
     prefix plus data. The length prefix indicates the number of bytes
     in the value. A `VARCHAR' column uses one length byte if values
     require no more than 255 bytes, two length bytes if values may
     require more than 255 bytes.

     *Note*:

     MySQL 5.1 follows the standard SQL specification, and does _not_
     remove trailing spaces from `VARCHAR' values.

     `VARCHAR' is shorthand for `CHARACTER VARYING'. `NATIONAL VARCHAR'
     is the standard SQL way to define that a `VARCHAR' column should
     use some predefined character set. MySQL 4.1 and up uses `utf8' as
     this predefined character set.  *Note charset-national::.
     `NVARCHAR' is shorthand for `NATIONAL VARCHAR'.

   * `BINARY(M)'

     The `BINARY' type is similar to the `CHAR' type, but stores binary
     byte strings rather than non-binary character strings.  M
     represents the column length in bytes.

   * `VARBINARY(M)'

     The `VARBINARY' type is similar to the `VARCHAR' type, but stores
     binary byte strings rather than non-binary character strings.  M
     represents the maximum column length in bytes.

   * `TINYBLOB'

     A `BLOB' column with a maximum length of 255 (2^8 - 1) bytes. Each
     `TINYBLOB' value is stored using a one-byte length prefix that
     indicates the number of bytes in the value.

   * `TINYTEXT [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]'

     A `TEXT' column with a maximum length of 255 (2^8 - 1) characters.
     The effective maximum length is less if the value contains
     multi-byte characters. Each `TINYTEXT' value is stored using a
     one-byte length prefix that indicates the number of bytes in the
     value.

   * `BLOB[(M)]'

     A `BLOB' column with a maximum length of 65,535 (2^16 - 1) bytes.
     Each `BLOB' value is stored using a two-byte length prefix that
     indicates the number of bytes in the value.

     An optional length M can be given for this type. If this is done,
     MySQL creates the column as the smallest `BLOB' type large enough
     to hold values M bytes long.

   * `TEXT[(M)] [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]'

     A `TEXT' column with a maximum length of 65,535 (2^16 - 1)
     characters. The effective maximum length is less if the value
     contains multi-byte characters. Each `TEXT' value is stored using
     a two-byte length prefix that indicates the number of bytes in the
     value.

     An optional length M can be given for this type. If this is done,
     MySQL creates the column as the smallest `TEXT' type large enough
     to hold values M characters long.

   * `MEDIUMBLOB'

     A `BLOB' column with a maximum length of 16,777,215 (2^24 - 1)
     bytes.  Each `MEDIUMBLOB' value is stored using a three-byte
     length prefix that indicates the number of bytes in the value.

   * `MEDIUMTEXT [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]'

     A `TEXT' column with a maximum length of 16,777,215 (2^24 - 1)
     characters. The effective maximum length is less if the value
     contains multi-byte characters. Each `MEDIUMTEXT' value is stored
     using a three-byte length prefix that indicates the number of bytes
     in the value.

   * `LONGBLOB'

     A `BLOB' column with a maximum length of 4,294,967,295 or 4GB
     (2^32 - 1) bytes. The effective maximum length of `LONGBLOB'
     columns depends on the configured maximum packet size in the
     client/server protocol and available memory. Each `LONGBLOB' value
     is stored using a four-byte length prefix that indicates the
     number of bytes in the value.

   * `LONGTEXT [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]'

     A `TEXT' column with a maximum length of 4,294,967,295 or 4GB
     (2^32 - 1) characters. The effective maximum length is less if the
     value contains multi-byte characters. The effective maximum length
     of `LONGTEXT' columns also depends on the configured maximum
     packet size in the client/server protocol and available memory.
     Each `LONGTEXT' value is stored using a four-byte length prefix
     that indicates the number of bytes in the value.

   * `ENUM('VALUE1','VALUE2',...)  [CHARACTER SET CHARSET_NAME] [COLLATE
     COLLATION_NAME]'

     An enumeration. A string object that can have only one value,
     chosen from the list of values `'VALUE1'', `'VALUE2'', `...',
     `NULL' or the special `''' error value. An `ENUM' column can have
     a maximum of 65,535 distinct values. `ENUM' values are represented
     internally as integers.

   * `SET('VALUE1','VALUE2',...)  [CHARACTER SET CHARSET_NAME] [COLLATE
     COLLATION_NAME]'

     A set. A string object that can have zero or more values, each of
     which must be chosen from the list of values `'VALUE1'',
     `'VALUE2'', `...' A `SET' column can have a maximum of 64 members.
     `SET' values are represented internally as integers.


File: manual.info,  Node: data-type-defaults,  Prev: string-type-overview,  Up: data-type-overview

10.1.4 Data Type Default Values
-------------------------------

The `DEFAULT VALUE' clause in a data type specification indicates a
default value for a column. With one exception, the default value must
be a constant; it cannot be a function or an expression. This means,
for example, that you cannot set the default for a date column to be
the value of a function such as `NOW()' or `CURRENT_DATE'. The
exception is that you can specify `CURRENT_TIMESTAMP' as the default
for a `TIMESTAMP' column. See *Note timestamp::.

`BLOB' and `TEXT' columns cannot be assigned a default value.

If a column definition includes no explicit `DEFAULT' value, MySQL
determines the default value as follows:

If the column can take `NULL' as a value, the column is defined with an
explicit `DEFAULT NULL' clause.

If the column cannot take `NULL' as the value, MySQL defines the column
with no explicit `DEFAULT' clause. For data entry, if an `INSERT' or
`REPLACE' statement includes no value for the column, MySQL handles the
column according to the SQL mode in effect at the time:

   * If strict SQL mode is not enabled, MySQL sets the column to the
     implicit default value for the column data type.

   * If strict mode is enabled, an error occurs for transactional
     tables and the statement is rolled back. For non-transactional
     tables, an error occurs, but if this happens for the second or
     subsequent row of a multiple-row statement, the preceding rows
     will have been inserted.

Suppose that a table `t' is defined as follows:

     CREATE TABLE t (i INT NOT NULL);

In this case, `i' has no explicit default, so in strict mode each of
the following statements produce an error and no row is inserted. When
not using strict mode, only the third statement produces an error; the
implicit default is inserted for the first two statements, but the
third fails because `DEFAULT(i)' cannot produce a value:

     INSERT INTO t VALUES();
     INSERT INTO t VALUES(DEFAULT);
     INSERT INTO t VALUES(DEFAULT(i));

See *Note server-sql-mode::.

For a given table, you can use the `SHOW CREATE TABLE' statement to see
which columns have an explicit `DEFAULT' clause.

Implicit defaults are defined as follows:

   * For numeric types, the default is `0', with the exception that for
     integer or floating-point types declared with the `AUTO_INCREMENT'
     attribute, the default is the next value in the sequence.

   * For date and time types other than `TIMESTAMP', the default is the
     appropriate `zero' value for the type. For the first `TIMESTAMP'
     column in a table, the default value is the current date and time.
     See *Note date-and-time-types::.

   * For string types other than `ENUM', the default value is the empty
     string. For `ENUM', the default is the first enumeration value.

`SERIAL DEFAULT VALUE' in the definition of an integer column is an
alias for `NOT NULL AUTO_INCREMENT UNIQUE'.


File: manual.info,  Node: numeric-types,  Next: date-and-time-types,  Prev: data-type-overview,  Up: data-types

10.2 Numeric Types
==================

MySQL supports all of the standard SQL numeric data types. These types
include the exact numeric data types (`INTEGER', `SMALLINT', `DECIMAL',
and `NUMERIC'), as well as the approximate numeric data types (`FLOAT',
`REAL', and `DOUBLE PRECISION'). The keyword `INT' is a synonym for
`INTEGER', and the keyword `DEC' is a synonym for `DECIMAL'. For
numeric type storage requirements, see *Note storage-requirements::.

The numeric types used for the results of calculations depends on the
operations being performed and the numeric types of the operands; for
more information, see *Note arithmetic-functions::.

The `BIT' data type stores bit-field values and is supported for
`MyISAM', `MEMORY', `InnoDB', and `NDBCLUSTER' tables.

As an extension to the SQL standard, MySQL also supports the integer
types `TINYINT', `MEDIUMINT', and `BIGINT'. The following table shows
the required storage and range for each of the integer types.

*Type*      *Bytes*     *Minimum Value*           *Maximum Value*
                        *(Signed/Unsigned)*       *(Signed/Unsigned)*
`TINYINT'   1           `-128'                    `127'
                        `0'                       `255'
`SMALLINT'  2           `-32768'                  `32767'
                        `0'                       `65535'
`MEDIUMINT' 3           `-8388608'                `8388607'
                        `0'                       `16777215'
`INT'       4           `-2147483648'             `2147483647'
                        `0'                       `4294967295'
`BIGINT'    8           `-9223372036854775808'    `9223372036854775807'
                        `0'                       `18446744073709551615'

Another extension is supported by MySQL for optionally specifying the
display width of integer data types in parentheses following the base
keyword for the type (for example, `INT(4)'). This optional display
width is used to display integer values having a width less than the
width specified for the column by left-padding them with spaces.

The display width does _not_ constrain the range of values that can be
stored in the column, nor the number of digits that are displayed for
values having a width exceeding that specified for the column. For
example, a column specified as `SMALLINT(3)' has the usual `SMALLINT'
range of `-32768' to `32767', and values outside the range allowed by
three characters are displayed using more than three characters.

When used in conjunction with the optional extension attribute
`ZEROFILL', the default padding of spaces is replaced with zeros. For
example, for a column declared as `INT(5) ZEROFILL', a value of `4' is
retrieved as `00004'.  Note that if you store larger values than the
display width in an integer column, you may experience problems when
MySQL generates temporary tables for some complicated joins, because in
these cases MySQL assumes that the data fits into the original column
width.

*Note*:

The `ZEROFILL' attribute is ignored when a column is involved in
expressions or `UNION' queries.

All integer types can have an optional (non-standard) attribute
`UNSIGNED'. Unsigned values can be used when you want to allow only
non-negative numbers in a column and you need a larger upper numeric
range for the column. For example, if an `INT' column is `UNSIGNED', the
size of the column's range is the same but its endpoints shift from
`-2147483648' and `2147483647' up to `0' and `4294967295'.

Floating-point and fixed-point types also can be `UNSIGNED'. As with
integer types, this attribute prevents negative values from being
stored in the column. However, unlike the integer types, the upper
range of column values remains the same.

If you specify `ZEROFILL' for a numeric column, MySQL automatically
adds the `UNSIGNED' attribute to the column.

Integer or floating-point data types can have the additional attribute
`AUTO_INCREMENT'. When you insert a value of `NULL' (recommended) or
`0' into an indexed `AUTO_INCREMENT' column, the column is set to the
next sequence value. Typically this is `VALUE+1', where VALUE is the
largest value for the column currently in the table. `AUTO_INCREMENT'
sequences begin with `1'.

For floating-point data types, MySQL uses four bytes for
single-precision values and eight bytes for double-precision values.

The `FLOAT' and `DOUBLE' data types are used to represent approximate
numeric data values. For `FLOAT', the SQL standard allows an optional
specification of the precision (but not the range of the exponent) in
bits following the keyword `FLOAT' in parentheses. MySQL also supports
this optional precision specification, but the precision value is used
only to determine storage size. A precision from 0 to 23 results in a
four-byte single-precision `FLOAT' column. A precision from 24 to 53
results in an eight-byte double-precision `DOUBLE' column.

MySQL allows a non-standard syntax: `FLOAT(M,D)' or `REAL(M,D)' or
`DOUBLE PRECISION(M,D)'.  Here, ``(M,D)'' means than values can be
stored with up to M digits in total, of which D digits may be after the
decimal point. For example, a column defined as `FLOAT(7,4)' will look
like `-999.9999' when displayed. MySQL performs rounding when storing
values, so if you insert `999.00009' into a `FLOAT(7,4)' column, the
approximate result is `999.0001'.

MySQL treats `DOUBLE' as a synonym for `DOUBLE PRECISION' (a
non-standard extension).  MySQL also treats `REAL' as a synonym for
`DOUBLE PRECISION' (a non-standard variation), unless the
`REAL_AS_FLOAT' SQL mode is enabled.

For maximum portability, code requiring storage of approximate numeric
data values should use `FLOAT' or `DOUBLE PRECISION' with no
specification of precision or number of digits.

The `DECIMAL' and `NUMERIC' data types are used to store exact numeric
data values. In MySQL, `NUMERIC' is implemented as `DECIMAL'. These
types are used to store values for which it is important to preserve
exact precision, for example with monetary data.

MySQL 5.1 stores `DECIMAL' and `NUMERIC' values in binary format.
Before MySQL 5.0.3, they were stored as strings. See *Note
precision-math::.

When declaring a `DECIMAL' or `NUMERIC' column, the precision and scale
can be (and usually is) specified; for example:

     salary DECIMAL(5,2)

In this example, `5' is the precision and `2' is the scale. The
precision represents the number of significant digits that are stored
for values, and the scale represents the number of digits that can be
stored following the decimal point. If the scale is 0, `DECIMAL' and
`NUMERIC' values contain no decimal point or fractional part.

Standard SQL requires that the `salary' column be able to store any
value with five digits and two decimals. In this case, therefore, the
range of values that can be stored in the `salary' column is from
`-999.99' to `999.99'.

In standard SQL, the syntax `DECIMAL(M)' is equivalent to
`DECIMAL(M,0)'.  Similarly, the syntax `DECIMAL' is equivalent to
`DECIMAL(M,0)', where the implementation is allowed to decide the value
of M. MySQL supports both of these variant forms of the `DECIMAL' and
`NUMERIC' syntax. The default value of M is 10.

The maximum number of digits for `DECIMAL' or `NUMERIC' is 65, but the
actual range for a given `DECIMAL' or `NUMERIC' column can be
constrained by the precision or scale for a given column.  When such a
column is assigned a value with more digits following the decimal point
than are allowed by the specified scale, the value is converted to that
scale. (The precise behavior is operating system-specific, but
generally the effect is truncation to the allowable number of digits.)

The `BIT' data type is used to store bit-field values. A type of
`BIT(M)' allows for storage of M-bit values.  M can range from 1 to 64.

To specify bit values, `b'VALUE'' notation can be used. VALUE is a
binary value written using zeros and ones. For example, `b'111'' and
`b'10000000'' represent 7 and 128, respectively. See *Note
bit-field-values::.

If you assign a value to a `BIT(M)' column that is less than M bits
long, the value is padded on the left with zeros. For example,
assigning a value of `b'101'' to a `BIT(6)' column is, in effect, the
same as assigning `b'000101''.

When asked to store a value in a numeric column that is outside the
data type's allowable range, MySQL's behavior depends on the SQL mode
in effect at the time. For example, if no restrictive modes are
enabled, MySQL clips the value to the appropriate endpoint of the range
and stores the resulting value instead.  However, if the mode is set to
`TRADITIONAL', MySQL rejects a value that is out of range with an
error, and the insert fails, in accordance with the SQL standard.

In non-strict mode, when an out-of-range value is assigned to an
integer column, MySQL stores the value representing the corresponding
endpoint of the column data type range. If you store 256 into a
`TINYINT' or `TINYINT UNSIGNED' column, MySQL stores 127 or 255,
respectively.  When a floating-point or fixed-point column is assigned
a value that exceeds the range implied by the specified (or default)
precision and scale, MySQL stores the value representing the
corresponding endpoint of that range.

Conversions that occur due to clipping when MySQL is not operating in
strict mode are reported as warnings for `ALTER TABLE', `LOAD DATA
INFILE', `UPDATE', and multiple-row `INSERT' statements. When MySQL is
operating in strict mode, these statements fail, and some or all of the
values will not be inserted or changed, depending on whether the table
is a transactional table and other factors. For details, see *Note
server-sql-mode::.


File: manual.info,  Node: date-and-time-types,  Next: string-types,  Prev: numeric-types,  Up: data-types

10.3 Date and Time Types
========================

* Menu:

* datetime::                     The `DATETIME', `DATE', and `TIMESTAMP' Types
* time::                         The `TIME' Type
* year::                         The `YEAR' Type
* y2k-issues::                   Year 2000 Issues and Date Types

The date and time types for representing temporal values are
`DATETIME', `DATE', `TIMESTAMP', `TIME', and `YEAR'. Each temporal type
has a range of legal values, as well as a `zero' value that may be used
when you specify an illegal value that MySQL cannot represent. The
`TIMESTAMP' type has special automatic updating behavior, described
later on. For temporal type storage requirements, see *Note
storage-requirements::.

MySQL gives warnings or errors if you try to insert an illegal date. By
setting the SQL mode to the appropriate value, you can specify more
exactly what kind of dates you want MySQL to support.  (See *Note
server-sql-mode::.) You can get MySQL to accept certain dates, such as
`'1999-11-31'', by using the `ALLOW_INVALID_DATES' SQL mode. This is
useful when you want to store a `possibly wrong' value which the user
has specified (for example, in a web form) in the database for future
processing. Under this mode, MySQL verifies only that the month is in
the range from 0 to 12 and that the day is in the range from 0 to 31.
These ranges are defined to include zero because MySQL allows you to
store dates where the day or month and day are zero in a `DATE' or
`DATETIME' column. This is extremely useful for applications that need
to store a birthdate for which you do not know the exact date. In this
case, you simply store the date as `'1999-00-00'' or `'1999-01-00''. If
you store dates such as these, you should not expect to get correct
results for functions such as `DATE_SUB()' or `DATE_ADD()' that require
complete dates. (If you do _not_ want to allow zero in dates, you can
use the `NO_ZERO_IN_DATE' SQL mode).

Prior to MySQL 5.1.18, when `DATE' values are compared with `DATETIME'
values, the time portion of the `DATETIME' value is ignored, or the
comparison could be performed as a string compare. Starting from MySQL
5.1.18, a `DATE' value is coerced to the `DATETIME' type by adding the
time portion as `'00:00:00''. To mimic the old behavior, use the
`CAST()' function to cause the comparison operands to be treated as
previously. For example:

     DATE_COL = CAST(NOW() AS DATE);

MySQL also allows you to store `'0000-00-00'' as a `dummy date' (if you
are not using the `NO_ZERO_DATE' SQL mode). This is in some cases more
convenient (and uses less data and index space) than using `NULL'
values.

Here are some general considerations to keep in mind when working with
date and time types:

   * MySQL retrieves values for a given date or time type in a standard
     output format, but it attempts to interpret a variety of formats
     for input values that you supply (for example, when you specify a
     value to be assigned to or compared to a date or time type). Only
     the formats described in the following sections are supported. It
     is expected that you supply legal values. Unpredictable results
     may occur if you use values in other formats.

   * Dates containing two-digit year values are ambiguous because the
     century is unknown. MySQL interprets two-digit year values using
     the following rules:

        * Year values in the range `70-99' are converted to `1970-1999'.

        * Year values in the range `00-69' are converted to `2000-2069'.

   * Although MySQL tries to interpret values in several formats, dates
     always must be given in year-month-day order (for example,
     `'98-09-04''), rather than in the month-day-year or day-month-year
     orders commonly used elsewhere (for example, `'09-04-98'',
     `'04-09-98'').

   * MySQL automatically converts a date or time type value to a number
     if the value is used in a numeric context and vice versa.

   * By default, when MySQL encounters a value for a date or time type
     that is out of range or otherwise illegal for the type (as
     described at the beginning of this section), it converts the value
     to the `zero' value for that type. The exception is that
     out-of-range `TIME' values are clipped to the appropriate endpoint
     of the `TIME' range.

     The following table shows the format of the `zero' value for each
     type. Note that the use of these values produces warnings if the
     `NO_ZERO_DATE' SQL mode is enabled.

     *Data Type*          *`Zero' Value*
     `DATETIME'           `'0000-00-00 00:00:00''
     `DATE'               `'0000-00-00''
     `TIMESTAMP'          `'0000-00-00 00:00:00''
     `TIME'               `'00:00:00''
     `YEAR'               `0000'

   * The `zero' values are special, but you can store or refer to them
     explicitly using the values shown in the table. You can also do
     this using the values `'0'' or `0', which are easier to write.

   * `Zero' date or time values used through MyODBC are converted
     automatically to `NULL' in MyODBC 2.50.12 and above, because ODBC
     cannot handle such values.


File: manual.info,  Node: datetime,  Next: time,  Prev: date-and-time-types,  Up: date-and-time-types

10.3.1 The `DATETIME', `DATE', and `TIMESTAMP' Types
----------------------------------------------------

* Menu:

* timestamp::                    `TIMESTAMP' Properties

The `DATETIME', `DATE', and `TIMESTAMP' types are related. This section
describes their characteristics, how they are similar, and how they
differ.

The `DATETIME' type is used when you need values that contain both date
and time information. MySQL retrieves and displays `DATETIME' values in
`'YYYY-MM-DD HH:MM:SS'' format. The supported range is `'1000-01-01
00:00:00'' to `'9999-12-31 23:59:59''.

The `DATE' type is used when you need only a date value, without a time
part. MySQL retrieves and displays `DATE' values in `'YYYY-MM-DD''
format. The supported range is `'1000-01-01'' to `'9999-12-31''.

For the `DATETIME' and `DATE' range descriptions, `supported' means
that although earlier values might work, there is no guarantee.

The `TIMESTAMP' data type has a range of `'1970-01-01 00:00:01'' UTC to
`'2038-01-09 03:14:07'' UTC. It has varying properties, depending on
the MySQL version and the SQL mode the server is running in. These
properties are described later in this section.

You can specify `DATETIME', `DATE', and `TIMESTAMP' values using any of
a common set of formats:

   * As a string in either `'YYYY-MM-DD HH:MM:SS'' or `'YY-MM-DD
     HH:MM:SS'' format. A `relaxed' syntax is allowed: Any punctuation
     character may be used as the delimiter between date parts or time
     parts. For example, `'98-12-31 11:30:45'', `'98.12.31 11+30+45'',
     `'98/12/31 11*30*45'', and `'98@12@31 11^30^45'' are equivalent.

   * As a string in either `'YYYY-MM-DD'' or `'YY-MM-DD'' format. A
     `relaxed' syntax is allowed here, too. For example, `'98-12-31'',
     `'98.12.31'', `'98/12/31'', and `'98@12@31'' are equivalent.

   * As a string with no delimiters in either `'YYYYMMDDHHMMSS'' or
     `'YYMMDDHHMMSS'' format, provided that the string makes sense as a
     date. For example, `'19970523091528'' and `'970523091528'' are
     interpreted as `'1997-05-23 09:15:28'', but `'971122129015'' is
     illegal (it has a nonsensical minute part) and becomes `'0000-00-00
     00:00:00''.

   * As a string with no delimiters in either `'YYYYMMDD'' or `'YYMMDD''
     format, provided that the string makes sense as a date. For
     example, `'19970523'' and `'970523'' are interpreted as
     `'1997-05-23'', but `'971332'' is illegal (it has nonsensical
     month and day parts) and becomes `'0000-00-00''.

   * As a number in either `YYYYMMDDHHMMSS' or `YYMMDDHHMMSS' format,
     provided that the number makes sense as a date. For example,
     `19830905132800' and `830905132800' are interpreted as
     `'1983-09-05 13:28:00''.

   * As a number in either `YYYYMMDD' or `YYMMDD' format, provided that
     the number makes sense as a date. For example, `19830905' and
     `830905' are interpreted as `'1983-09-05''.

   * As the result of a function that returns a value that is
     acceptable in a `DATETIME', `DATE', or `TIMESTAMP' context, such
     as `NOW()' or `CURRENT_DATE'.

A microseconds part is allowable in temporal values in some contexts,
such as in literal values, and in the arguments to or return values
from some temporal functions. Microseconds are specified as a trailing
`.uuuuuu' part in the value. Example:

     mysql> SELECT MICROSECOND('2010-12-10 14:12:09.019473');
     +-------------------------------------------+
     | MICROSECOND('2010-12-10 14:12:09.019473') |
     +-------------------------------------------+
     |                                     19473 |
     +-------------------------------------------+

However, microseconds cannot be stored into a column of any temporal
data type. Any microseconds part is discarded.

Conversion of `TIME' or `DATETIME' values to numeric form (for example,
by adding `+0') results in a double value with a microseconds part of
`.000000':

     mysql> SELECT CURTIME(), CURTIME()+0;
     +-----------+---------------+
     | CURTIME() | CURTIME()+0   |
     +-----------+---------------+
     | 10:41:36  | 104136.000000 |
     +-----------+---------------+
     mysql> SELECT NOW(), NOW()+0;
     +---------------------+-----------------------+
     | NOW()               | NOW()+0               |
     +---------------------+-----------------------+
     | 2007-11-30 10:41:47 | 20071130104147.000000 |
     +---------------------+-----------------------+

Illegal `DATETIME', `DATE', or `TIMESTAMP' values are converted to the
`zero' value of the appropriate type (`'0000-00-00 00:00:00'' or
`'0000-00-00'').

For values specified as strings that include date part delimiters, it
is not necessary to specify two digits for month or day values that are
less than `10'.  `'1979-6-9'' is the same as `'1979-06-09''. Similarly,
for values specified as strings that include time part delimiters, it
is not necessary to specify two digits for hour, minute, or second
values that are less than `10'.  `'1979-10-30 1:2:3'' is the same as
`'1979-10-30 01:02:03''.

Values specified as numbers should be 6, 8, 12, or 14 digits long. If a
number is 8 or 14 digits long, it is assumed to be in `YYYYMMDD' or
`YYYYMMDDHHMMSS' format and that the year is given by the first 4
digits. If the number is 6 or 12 digits long, it is assumed to be in
`YYMMDD' or `YYMMDDHHMMSS' format and that the year is given by the
first 2 digits. Numbers that are not one of these lengths are
interpreted as though padded with leading zeros to the closest length.

Values specified as non-delimited strings are interpreted using their
length as given. If the string is 8 or 14 characters long, the year is
assumed to be given by the first 4 characters.  Otherwise, the year is
assumed to be given by the first 2 characters. The string is
interpreted from left to right to find year, month, day, hour, minute,
and second values, for as many parts as are present in the string. This
means you should not use strings that have fewer than 6 characters. For
example, if you specify `'9903'', thinking that represents March, 1999,
MySQL inserts a `zero' date value into your table. This occurs because
the year and month values are `99' and `03', but the day part is
completely missing, so the value is not a legal date.  However, you can
explicitly specify a value of zero to represent missing month or day
parts. For example, you can use `'990300'' to insert the value
`'1999-03-00''.

You can to some extent assign values of one date type to an object of a
different date type. However, there may be some alteration of the value
or loss of information:

   * If you assign a `DATE' value to a `DATETIME' or `TIMESTAMP'
     object, the time part of the resulting value is set to
     `'00:00:00'' because the `DATE' value contains no time information.

   * If you assign a `DATETIME' or `TIMESTAMP' value to a `DATE'
     object, the time part of the resulting value is deleted because the
     `DATE' type stores no time information.

   * Remember that although `DATETIME', `DATE', and `TIMESTAMP' values
     all can be specified using the same set of formats, the types do
     not all have the same range of values. For example, `TIMESTAMP'
     values cannot be earlier than `1970' UTC or later than
     `'2038-01-09 03:14:07'' UTC. This means that a date such as
     `'1968-01-01'', while legal as a `DATETIME' or `DATE' value, is
     not valid as a `TIMESTAMP' value and is converted to `0'.

Be aware of certain pitfalls when specifying date values:

   * The relaxed format allowed for values specified as strings can be
     deceiving. For example, a value such as `'10:11:12'' might look
     like a time value because of the ``:'' delimiter, but if used in a
     date context is interpreted as the year `'2010-11-12''. The value
     `'10:45:15'' is converted to `'0000-00-00'' because `'45'' is not
     a legal month.

   * The server requires that month and day values be legal, and not
     merely in the range 1 to 12 and 1 to 31, respectively.  With
     strict mode disabled, invalid dates such as `'2004-04-31'' are
     converted to `'0000-00-00'' and a warning is generated.  With
     strict mode enabled, invalid dates generate an error.  To allow
     such dates, enable `ALLOW_INVALID_DATES'. See *Note
     server-sql-mode::, for more information.

   * MySQL does not accept timestamp values that include a zero in the
     day or month column or values that are not a valid date. The sole
     exception to this rule is the special value `'0000-00-00
     00:00:00''.

   * Dates containing two-digit year values are ambiguous because the
     century is unknown. MySQL interprets two-digit year values using
     the following rules:

        * Year values in the range `00-69' are converted to `2000-2069'.

        * Year values in the range `70-99' are converted to `1970-1999'.


File: manual.info,  Node: timestamp,  Prev: datetime,  Up: datetime

10.3.1.1 `TIMESTAMP' Properties
...............................

`TIMESTAMP' columns are displayed in the same format as `DATETIME'
columns. In other words, the display width is fixed at 19 characters,
and the format is `'YYYY-MM-DD HH:MM:SS''.

`TIMESTAMP' values are converted from the current time zone to UTC for
storage, and converted back from UTC to the current time zone for
retrieval. (This occurs only for the `TIMESTAMP' data type, not for
other types such as `DATETIME'.) By default, the current time zone for
each connection is the server's time.  The time zone can be set on a
per-connection basis, as described in *Note time-zone-support::. As
long as the time zone setting remains constant, you get back the same
value you store. If you store a `TIMESTAMP' value, and then change the
time zone and retrieve the value, the retrieved value is different from
the value you stored.  This occurs because the same time zone was not
used for conversion in both directions. The current time zone is
available as the value of the `time_zone' system variable.

The `TIMESTAMP' data type offers automatic initialization and updating.
You can choose whether to use these properties and which column should
have them:

   * For one `TIMESTAMP' column in a table, you can assign the current
     timestamp as the default value and the auto-update value. It is
     possible to have the current timestamp be the default value for
     initializing the column, for the auto-update value, or both. It is
     not possible to have the current timestamp be the default value
     for one column and the auto-update value for another column.

   * Any single `TIMESTAMP' column in a table can be used as the one
     that is initialized to the current date and time, or updated
     automatically. This need not be the first `TIMESTAMP' column.

   * If a `DEFAULT' value is specified for the first `TIMESTAMP' column
     in a table, it is not ignored. The default can be
     `CURRENT_TIMESTAMP' or a constant date and time value.

   * In a `CREATE TABLE' statement, the first `TIMESTAMP' column can be
     declared in any of the following ways:

        * With both `DEFAULT CURRENT_TIMESTAMP' and `ON UPDATE
          CURRENT_TIMESTAMP' clauses, the column has the current
          timestamp for its default value, and is automatically updated.

        * With neither `DEFAULT' nor `ON UPDATE' clauses, it is the same
          as `DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP'.

        * With a `DEFAULT CURRENT_TIMESTAMP' clause and no `ON UPDATE'
          clause, the column has the current timestamp for its default
          value but is not automatically updated.

        * With no `DEFAULT' clause and with an `ON UPDATE
          CURRENT_TIMESTAMP' clause, the column has a default of 0 and
          is automatically updated.

        * With a constant `DEFAULT' value, the column has the given
          default and is not automatically initialized to the current
          timestamp. If the column also has an `ON UPDATE
          CURRENT_TIMESTAMP' clause, it is automatically updated;
          otherwise, it has a constant default and is not automatically
          updated.

     In other words, you can use the current timestamp for both the
     initial value and the auto-update value, or either one, or
     neither. (For example, you can specify `ON UPDATE' to enable
     auto-update without also having the column auto-initialized.) The
     following column definitions demonstrate each of the possiblities:

        * Auto-initialization and auto-update:

               ts TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP

        * Auto-initialization only:

               ts TIMESTAMP DEFAULT CURRENT_TIMESTAMP

        * Auto-update only:

               ts TIMESTAMP DEFAULT 0 ON UPDATE CURRENT_TIMESTAMP

        * Neither:

               ts TIMESTAMP DEFAULT 0

   * To specify automatic default or updating for a `TIMESTAMP' column
     other than the first one, you must suppress the automatic
     initialization and update behaviors for the first `TIMESTAMP'
     column by explicitly assigning it a constant `DEFAULT' value (for
     example, `DEFAULT 0' or `DEFAULT '2003-01-01 00:00:00''). Then,
     for the other `TIMESTAMP' column, the rules are the same as for
     the first `TIMESTAMP' column, except that if you omit both of the
     `DEFAULT' and `ON UPDATE' clauses, no automatic initialization or
     updating occurs.

     Example:

          CREATE TABLE t (
              ts1 TIMESTAMP DEFAULT 0,
              ts2 TIMESTAMP DEFAULT CURRENT_TIMESTAMP
                            ON UPDATE CURRENT_TIMESTAMP);

   * `CURRENT_TIMESTAMP' or any of its synonyms (`CURRENT_TIMESTAMP()',
     `NOW()', `LOCALTIME', `LOCALTIME()', `LOCALTIMESTAMP', or
     `LOCALTIMESTAMP()') can be used in the `DEFAULT' and `ON UPDATE'
     clauses. They all mean `the current timestamp.' (`UTC_TIMESTAMP'
     is not allowed. Its range of values does not align with those of
     the `TIMESTAMP' column anyway unless the current time zone is
     `UTC'.)

   * The order of the `DEFAULT' and `ON UPDATE' attributes does not
     matter.  If both `DEFAULT' and `ON UPDATE' are specified for a
     `TIMESTAMP' column, either can precede the other. For example,
     these statements are equivalent:

          CREATE TABLE t (ts TIMESTAMP);
          CREATE TABLE t (ts TIMESTAMP DEFAULT CURRENT_TIMESTAMP
                                       ON UPDATE CURRENT_TIMESTAMP);
          CREATE TABLE t (ts TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
                                       DEFAULT CURRENT_TIMESTAMP);

*Note*:

The examples that use `DEFAULT 0' will not work if the `NO_ZERO_DATE'
SQL mode is enabled because that mode causes `zero' date values
(specified as `0', `'0000-00-00', or `'0000-00-00 00:00:00'') to be
rejected. Be aware that the `TRADITIONAL' SQL mode includes
`NO_ZERO_DATE'.

`TIMESTAMP' columns are `NOT NULL' by default, cannot contain `NULL'
values, and assigning `NULL' assigns the current timestamp.  However, a
`TIMESTAMP' column can be allowed to contain `NULL' by declaring it
with the `NULL' attribute. In this case, the default value also becomes
`NULL' unless overridden with a `DEFAULT' clause that specifies a
different default value. `DEFAULT NULL' can be used to explicitly
specify `NULL' as the default value. (For a `TIMESTAMP' column not
declared with the `NULL' attribute, `DEFAULT NULL' is illegal.) If a
`TIMESTAMP' column allows `NULL' values, assigning `NULL' sets it to
`NULL', not to the current timestamp.

The following table contains several `TIMESTAMP' columns that allow
`NULL' values:

     CREATE TABLE t
     (
       ts1 TIMESTAMP NULL DEFAULT NULL,
       ts2 TIMESTAMP NULL DEFAULT 0,
       ts3 TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP
     );

Note that a `TIMESTAMP' column that allows `NULL' values will _not_
take on the current timestamp except under one of the following
conditions:

   * Its default value is defined as `CURRENT_TIMESTAMP'

   * `NOW()' or `CURRENT_TIMESTAMP' is inserted into the column

In other words, a `TIMESTAMP' column defined as `NULL' will
auto-initialize only if it is created using a definition such as the
following:

     CREATE TABLE t (ts TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP);

Otherwise -- that is, if the `TIMESTAMP' column is defined to allow
`NULL' values but not using `DEFAULT CURRENT_TIMESTAMP', as shown
here...

     CREATE TABLE t1 (ts TIMESTAMP NULL DEFAULT NULL);
     CREATE TABLE t2 (ts TIMESTAMP NULL DEFAULT '0000-00-00 00:00:00');

...then you must explicitly insert a value corresponding to the current
date and time. For example:

     INSERT INTO t1 VALUES (NOW());
     INSERT INTO t2 VALUES (CURRENT_TIMESTAMP);

*Note*:

The MySQL server can be run with the `MAXDB' SQL mode enabled. When the
server runs with this mode enabled, `TIMESTAMP' is identical with
`DATETIME'. That is, if this mode is enabled at the time that a table
is created, `TIMESTAMP' columns are created as `DATETIME' columns. As a
result, such columns use `DATETIME' display format, have the same range
of values, and there is no automatic initialization or updating to the
current date and time.

To enable `MAXDB' mode, set the server SQL mode to `MAXDB' at startup
using the `--sql-mode=MAXDB' server option or by setting the global
`sql_mode' variable at runtime:

     mysql> SET GLOBAL sql_mode=MAXDB;

A client can cause the server to run in `MAXDB' mode for its own
connection as follows:

     mysql> SET SESSION sql_mode=MAXDB;


File: manual.info,  Node: time,  Next: year,  Prev: datetime,  Up: date-and-time-types

10.3.2 The `TIME' Type
----------------------

MySQL retrieves and displays `TIME' values in `'HH:MM:SS'' format (or
`'HHH:MM:SS'' format for large hours values).  `TIME' values may range
from `'-838:59:59'' to `'838:59:59''. The hours part may be so large
because the `TIME' type can be used not only to represent a time of day
(which must be less than 24 hours), but also elapsed time or a time
interval between two events (which may be much greater than 24 hours,
or even negative).

You can specify `TIME' values in a variety of formats:

   * As a string in `'D HH:MM:SS.fraction'' format. You can also use
     one of the following `relaxed' syntaxes: `'HH:MM:SS.fraction'',
     `'HH:MM:SS'', `'HH:MM'', `'D HH:MM:SS'', `'D HH:MM'', `'D HH'', or
     `'SS''. Here `D' represents days and can have a value from 0 to
     34. Note that MySQL does not store the fraction part.

   * As a string with no delimiters in `'HHMMSS'' format, provided that
     it makes sense as a time. For example, `'101112'' is understood as
     `'10:11:12'', but `'109712'' is illegal (it has a nonsensical
     minute part) and becomes `'00:00:00''.

   * As a number in `HHMMSS' format, provided that it makes sense as a
     time. For example, `101112' is understood as `'10:11:12''. The
     following alternative formats are also understood: `SS', `MMSS',
     `HHMMSS', `HHMMSS.fraction'. Note that MySQL does not store the
     fraction part.

   * As the result of a function that returns a value that is
     acceptable in a `TIME' context, such as `CURRENT_TIME'.

A trailing `.uuuuuu' microseconds part of `TIME' values is allowed
under the same conditions as for other temporal values, as described in
*Note datetime::. This includes the property that any microseconds part
is discarded from values stored into `TIME' columns.

For `TIME' values specified as strings that include a time part
delimiter, it is not necessary to specify two digits for hours,
minutes, or seconds values that are less than `10'. `'8:3:2'' is the
same as `'08:03:02''.

Be careful about assigning abbreviated values to a `TIME' column.
Without colons, MySQL interprets values using the assumption that the
two rightmost digits represent seconds. (MySQL interprets `TIME' values
as elapsed time rather than as time of day.) For example, you might
think of `'1112'' and `1112' as meaning `'11:12:00'' (12 minutes after
11 o'clock), but MySQL interprets them as `'00:11:12'' (11 minutes, 12
seconds).  Similarly, `'12'' and `12' are interpreted as `'00:00:12''.
`TIME' values with colons, by contrast, are always treated as time of
the day. That is, `'11:12'' mean `'11:12:00'', not `'00:11:12''.

By default, values that lie outside the `TIME' range but are otherwise
legal are clipped to the closest endpoint of the range. For example,
`'-850:00:00'' and `'850:00:00'' are converted to `'-838:59:59'' and
`'838:59:59''. Illegal `TIME' values are converted to `'00:00:00''.
Note that because `'00:00:00'' is itself a legal `TIME' value, there is
no way to tell, from a value of `'00:00:00'' stored in a table, whether
the original value was specified as `'00:00:00'' or whether it was
illegal.

For more restrictive treatment of invalid `TIME' values, enable strict
SQL mode to cause errors to occur. See *Note server-sql-mode::.


File: manual.info,  Node: year,  Next: y2k-issues,  Prev: time,  Up: date-and-time-types

10.3.3 The `YEAR' Type
----------------------

The `YEAR' type is a one-byte type used for representing years. It can
be declared as `YEAR(2)' or `YEAR(4)' to specify a display width of two
or four characters. The default is four characters if no width is given.

For four-digit format, MySQL displays `YEAR' values in `YYYY' format,
with a range of `1901' to `2155'. For two-digit format, MySQL displays
values with a range of `70' (1970) to `69' (2069).

You can specify input `YEAR' values in a variety of formats:

   * As a four-digit string in the range `'1901'' to `'2155''.

   * As a four-digit number in the range `1901' to `2155'.

   * As a two-digit string in the range `'00'' to `'99''. Values in the
     ranges `'00'' to `'69'' and `'70'' to `'99'' are converted to
     `YEAR' values in the ranges `2000' to `2069' and `1970' to `1999'.

   * As a two-digit number in the range `1' to `99'. Values in the
     ranges `1' to `69' and `70' to `99' are converted to `YEAR' values
     in the ranges `2001' to `2069' and `1970' to `1999'. Note that the
     range for two-digit numbers is slightly different from the range
     for two-digit strings, because you cannot specify zero directly as
     a number and have it be interpreted as `2000'. You must specify it
     as a string `'0'' or `'00'' or it is interpreted as `0000'.

   * As the result of a function that returns a value that is
     acceptable in a `YEAR' context, such as `NOW()'.

Illegal `YEAR' values are converted to `0000'.


File: manual.info,  Node: y2k-issues,  Prev: year,  Up: date-and-time-types

10.3.4 Year 2000 Issues and Date Types
--------------------------------------

MySQL Server itself has no problems with Year 2000 (Y2K) compliance:

   * MySQL Server uses Unix time functions that handle dates into the
     year `2038' for `TIMESTAMP' values. For `DATE' and `DATETIME'
     values, dates through the year `9999' are accepted.

   * All MySQL date functions are implemented in one source file,
     `sql/time.cc', and are coded very carefully to be year 2000-safe.

   * In MySQL, the `YEAR' data type can store the years `0' and `1901'
     to `2155' in one byte and display them using two or four digits.
     All two-digit years are considered to be in the range `1970' to
     `2069', which means that if you store `01' in a `YEAR' column,
     MySQL Server treats it as `2001'.

Although MySQL Server itself is Y2K-safe, you may run into problems if
you use it with applications that are not Y2K-safe.  For example, many
old applications store or manipulate years using two-digit values
(which are ambiguous) rather than four-digit values. This problem may
be compounded by applications that use values such as `00' or `99' as
`missing' value indicators. Unfortunately, these problems may be
difficult to fix because different applications may be written by
different programmers, each of whom may use a different set of
conventions and date-handling functions.

Thus, even though MySQL Server has no Y2K problems, _it is the
application's responsibility to provide unambiguous input_. Any value
containing a two-digit year is ambiguous, because the century is
unknown. Such values must be interpreted into four-digit form because
MySQL stores years internally using four digits.

For `DATETIME', `DATE', `TIMESTAMP', and `YEAR' types, MySQL interprets
dates with ambiguous year values using the following rules:

   * Year values in the range `00-69' are converted to `2000-2069'.

   * Year values in the range `70-99' are converted to `1970-1999'.

Remember that these rules are only heuristics that provide reasonable
guesses as to what your data values mean. If the rules used by MySQL do
not produce the correct values, you should provide unambiguous input
containing four-digit year values.

`ORDER BY' properly sorts `YEAR' values that have two-digit years.

Some functions like `MIN()' and `MAX()' convert a `YEAR' to a number.
This means that a value with a two-digit year does not work properly
with these functions. The fix in this case is to convert the
`TIMESTAMP' or `YEAR' to four-digit year format.


File: manual.info,  Node: string-types,  Next: storage-requirements,  Prev: date-and-time-types,  Up: data-types

10.4 String Types
=================

* Menu:

* char::                         The `CHAR' and `VARCHAR' Types
* binary-varbinary::             The `BINARY' and `VARBINARY' Types
* blob::                         The `BLOB' and `TEXT' Types
* enum::                         The `ENUM' Type
* set::                          The `SET' Type

The string types are `CHAR', `VARCHAR', `BINARY', `VARBINARY', `BLOB',
`TEXT', `ENUM', and `SET'. This section describes how these types work
and how to use them in your queries. For string type storage
requirements, see *Note storage-requirements::.


File: manual.info,  Node: char,  Next: binary-varbinary,  Prev: string-types,  Up: string-types

10.4.1 The `CHAR' and `VARCHAR' Types
-------------------------------------

The `CHAR' and `VARCHAR' types are similar, but differ in the way they
are stored and retrieved. They also differ in maximum length and in
whether trailing spaces are retained.

The `CHAR' and `VARCHAR' types are declared with a length that
indicates the maximum number of characters you want to store. For
example, `CHAR(30)' can hold up to 30 characters.

The length of a `CHAR' column is fixed to the length that you declare
when you create the table. The length can be any value from 0 to 255.
When `CHAR' values are stored, they are right-padded with spaces to the
specified length. When `CHAR' values are retrieved, trailing spaces are
removed unless the `PAD_CHAR_TO_FULL_LENGTH' SQL mode is enabled.

Values in `VARCHAR' columns are variable-length strings. The length can
be specified as a value from 0 to 65,535. The effective maximum length
of a `VARCHAR' is subject to the maximum row size (65,535 bytes, which
is shared among all columns) and the character set used.

In contrast to `CHAR', `VARCHAR' values are stored as a one-byte or
two-byte length prefix plus data. The length prefix indicates the
number of bytes in the value. A column uses one length byte if values
require no more than 255 bytes, two length bytes if values may require
more than 255 bytes.

If strict SQL mode is not enabled and you assign a value to a `CHAR' or
`VARCHAR' column that exceeds the column's maximum length, the value is
truncated to fit and a warning is generated. For truncation of non-space
characters, you can cause an error to occur (rather than a warning) and
suppress insertion of the value by using strict SQL mode. See *Note
server-sql-mode::.

For `VARCHAR' columns, excess trailing spaces are truncated prior to
insertion and a warning is generated, regardless of the SQL mode in
use. For `CHAR' columns, truncation of excess trailing spaces from
inserted values is performed silently regardless of the SQL mode.

`VARCHAR' values are not padded when they are stored. Trailing spaces
are retained when values are stored and retrieved, in conformance with
standard SQL.

The following table illustrates the differences between `CHAR' and
`VARCHAR' by showing the result of storing various string values into
`CHAR(4)' and `VARCHAR(4)' columns (assuming that the column uses a
single-byte character set such as `latin1'):

*Value*     `CHAR(4)'   *Storage       `VARCHAR(4)'*Storage
                        Required*                  Required*
`'''        `'    ''    4 bytes        `'''        1 byte
`'ab''      `'ab  ''    4 bytes        `'ab''      3 bytes
`'abcd''    `'abcd''    4 bytes        `'abcd''    5 bytes
`'abcdefgh''`'abcd''    4 bytes        `'abcd''    5 bytes

The values shown as stored in the last row of the table apply _only
when not using strict mode_; if MySQL is running in strict mode, values
that exceed the column length are _not stored_, and an error results.

If a given value is stored into the `CHAR(4)' and `VARCHAR(4)' columns,
the values retrieved from the columns are not always the same because
trailing spaces are removed from `CHAR' columns upon retrieval.  The
following example illustrates this difference:

     mysql> CREATE TABLE vc (v VARCHAR(4), c CHAR(4));
     Query OK, 0 rows affected (0.01 sec)

     mysql> INSERT INTO vc VALUES ('ab  ', 'ab  ');
     Query OK, 1 row affected (0.00 sec)

     mysql> SELECT CONCAT('(', v, ')'), CONCAT('(', c, ')') FROM vc;
     +---------------------+---------------------+
     | CONCAT('(', v, ')') | CONCAT('(', c, ')') |
     +---------------------+---------------------+
     | (ab  )              | (ab)                |
     +---------------------+---------------------+
     1 row in set (0.06 sec)

Values in `CHAR' and `VARCHAR' columns are sorted and compared
according to the character set collation assigned to the column.

All MySQL collations are of type `PADSPACE'.  This means that all
`CHAR' and `VARCHAR' values in MySQL are compared without regard to any
trailing spaces. For example:

     mysql> CREATE TABLE names (myname CHAR(10), yourname VARCHAR(10));
     Query OK, 0 rows affected (0.09 sec)

     mysql> INSERT INTO names VALUES ('Monty ', 'Monty ');
     Query OK, 1 row affected (0.00 sec)

     mysql> SELECT myname = 'Monty  ', yourname = 'Monty  ' FROM names;
     +--------------------+----------------------+
     | myname = 'Monty  ' | yourname = 'Monty  ' |
     +--------------------+----------------------+
     |                  1 |                    1 |
     +--------------------+----------------------+
     1 row in set (0.00 sec)

This is true for all MySQL versions, and that it is not affected by the
server SQL mode.

For those cases where trailing pad characters are stripped or
comparisons ignore them, if a column has an index that requires unique
values, inserting into the column values that differ only in number of
trailing pad characters will result in a duplicate-key error. For
example, if a table contains `'a'', an attempt to store `'a '' causes a
duplicate-key error.


File: manual.info,  Node: binary-varbinary,  Next: blob,  Prev: char,  Up: string-types

10.4.2 The `BINARY' and `VARBINARY' Types
-----------------------------------------

The `BINARY' and `VARBINARY' types are similar to `CHAR' and `VARCHAR',
except that they contain binary strings rather than non-binary strings.
That is, they contain byte strings rather than character strings. This
means that they have no character set, and sorting and comparison are
based on the numeric values of the bytes in the values.

The allowable maximum length is the same for `BINARY' and `VARBINARY'
as it is for `CHAR' and `VARCHAR', except that the length for `BINARY'
and `VARBINARY' is a length in bytes rather than in characters.

The `BINARY' and `VARBINARY' data types are distinct from the `CHAR
BINARY' and `VARCHAR BINARY' data types. For the latter types, the
`BINARY' attribute does not cause the column to be treated as a binary
string column. Instead, it causes the binary collation for the column
character set to be used, and the column itself contains non-binary
character strings rather than binary byte strings. For example,
`CHAR(5) BINARY' is treated as `CHAR(5) CHARACTER SET latin1 COLLATE
latin1_bin', assuming that the default character set is `latin1'. This
differs from `BINARY(5)', which stores 5-bytes binary strings that have
no character set or collation.

If strict SQL mode is not enabled and you assign a value to a `BINARY'
or `VARBINARY' column that exceeds the column's maximum length, the
value is truncated to fit and a warning is generated. For cases of
truncation, you can cause an error to occur (rather than a warning) and
suppress insertion of the value by using strict SQL mode. See *Note
server-sql-mode::.

When `BINARY' values are stored, they are right-padded with the pad
value to the specified length. The pad value is `0x00' (the zero byte).
Values are right-padded with `0x00' on insert, and no trailing bytes
are removed on select. All bytes are significant in comparisons,
including `ORDER BY' and `DISTINCT' operations. `0x00' bytes and spaces
are different in comparisons, with `0x00' < space.

Example: For a `BINARY(3)' column, `'a '' becomes `'a \0'' when
inserted.  `'a\0'' becomes `'a\0\0'' when inserted. Both inserted
values remain unchanged when selected.

For `VARBINARY', there is no padding on insert and no bytes are
stripped on select. All bytes are significant in comparisons, including
`ORDER BY' and `DISTINCT' operations. `0x00' bytes and spaces are
different in comparisons, with `0x00' < space.

For those cases where trailing pad bytes are stripped or comparisons
ignore them, if a column has an index that requires unique values,
inserting into the column values that differ only in number of trailing
pad bytes will result in a duplicate-key error. For example, if a table
contains `'a'', an attempt to store `'a\0'' causes a duplicate-key
error.

You should consider the preceding padding and stripping characteristics
carefully if you plan to use the `BINARY' data type for storing binary
data and you require that the value retrieved be exactly the same as the
value stored. The following example illustrates how `0x00'-padding of
`BINARY' values affects column value comparisons:

     mysql> CREATE TABLE t (c BINARY(3));
     Query OK, 0 rows affected (0.01 sec)

     mysql> INSERT INTO t SET c = 'a';
     Query OK, 1 row affected (0.01 sec)

     mysql> SELECT HEX(c), c = 'a', c = 'a\0\0' from t;
     +--------+---------+-------------+
     | HEX(c) | c = 'a' | c = 'a\0\0' |
     +--------+---------+-------------+
     | 610000 |       0 |           1 |
     +--------+---------+-------------+
     1 row in set (0.09 sec)

If the value retrieved must be the same as the value specified for
storage with no padding, it might be preferable to use `VARBINARY' or
one of the `BLOB' data types instead.


File: manual.info,  Node: blob,  Next: enum,  Prev: binary-varbinary,  Up: string-types

10.4.3 The `BLOB' and `TEXT' Types
----------------------------------

A `BLOB' is a binary large object that can hold a variable amount of
data. The four `BLOB' types are `TINYBLOB', `BLOB', `MEDIUMBLOB', and
`LONGBLOB'.  These differ only in the maximum length of the values they
can hold. The four `TEXT' types are `TINYTEXT', `TEXT', `MEDIUMTEXT',
and `LONGTEXT'.  These correspond to the four `BLOB' types and have the
same maximum lengths and storage requirements. See *Note
storage-requirements::.

`BLOB' columns are treated as binary strings (byte strings). `TEXT'
columns are treated as non-binary strings (character strings). `BLOB'
columns have no character set, and sorting and comparison are based on
the numeric values of the bytes in column values.  `TEXT' columns have
a character set, and values are sorted and compared based on the
collation of the character set.

If strict SQL mode is not enabled and you assign a value to a `BLOB' or
`TEXT' column that exceeds the column's maximum length, the value is
truncated to fit and a warning is generated. For truncation of non-space
characters, you can cause an error to occur (rather than a warning) and
suppress insertion of the value by using strict SQL mode. See *Note
server-sql-mode::.

Beginning with MySQL MySQL 5.1.24, truncation of excess trailing spaces
from values to be inserted into `TEXT' columns always generates a
warning, regardless of the SQL mode.  (Bug#30059
(http://bugs.mysql.com/30059))

If a `TEXT' column is indexed, index entry comparisons are space-padded
at the end. This means that, if the index requires unique values,
duplicate-key errors will occur for values that differ only in the
number of trailing spaces.  For example, if a table contains `'a'', an
attempt to store `'a '' causes a duplicate-key error. This is not true
for `BLOB' columns.

In most respects, you can regard a `BLOB' column as a `VARBINARY'
column that can be as large as you like. Similarly, you can regard a
`TEXT' column as a `VARCHAR' column. `BLOB' and `TEXT' differ from
`VARBINARY' and `VARCHAR' in the following ways:

   * For indexes on `BLOB' and `TEXT' columns, you must specify an index
     prefix length. For `CHAR' and `VARCHAR', a prefix length is
     optional. See *Note indexes::.

   * `BLOB' and `TEXT' columns cannot have `DEFAULT' values.

`LONG' and `LONG VARCHAR' map to the `MEDIUMTEXT' data type. This is a
compatibility feature. If you use the `BINARY' attribute with a `TEXT'
data type, the column is assigned the binary collation of the column
character set.

MySQL Connector/ODBC defines `BLOB' values as `LONGVARBINARY' and `TEXT'
values as `LONGVARCHAR'.

Because `BLOB' and `TEXT' values can be extremely long, you might
encounter some constraints in using them:

   * Only the first `max_sort_length' bytes of the column are used when
     sorting. The default value of `max_sort_length' is 1024. This
     value can be changed using the `--max_sort_length=N' option when
     starting the `mysqld' server.  See *Note server-system-variables::.

     You can make more bytes significant in sorting or grouping by
     increasing the value of `max_sort_length' at runtime. Any client
     can change the value of its session `max_sort_length' variable:

          mysql> SET max_sort_length = 2000;
          mysql> SELECT id, comment FROM t
              -> ORDER BY comment;

     Another way to use `GROUP BY' or `ORDER BY' on a `BLOB' or `TEXT'
     column containing long values when you want more than
     `max_sort_length' bytes to be significant is to convert the column
     value into a fixed-length object. The standard way to do this is
     with the `SUBSTRING()' function. For example, the following
     statement causes 2000 bytes of the `comment' column to be taken
     into account for sorting:

          mysql> SELECT id, SUBSTRING(comment,1,2000) FROM t
              -> ORDER BY SUBSTRING(comment,1,2000);

   * The maximum size of a `BLOB' or `TEXT' object is determined by its
     type, but the largest value you actually can transmit between the
     client and server is determined by the amount of available memory
     and the size of the communications buffers. You can change the
     message buffer size by changing the value of the
     `max_allowed_packet' variable, but you must do so for both the
     server and your client program. For example, both `mysql' and
     `mysqldump' allow you to change the client-side
     `max_allowed_packet' value. See *Note server-parameters::, *Note
     mysql::, and *Note mysqldump::.  You may also want to compare the
     packet sizes and the size of the data objects you are storing with
     the storage requirements, see *Note storage-requirements::

Each `BLOB' or `TEXT' value is represented internally by a separately
allocated object. This is in contrast to all other data types, for
which storage is allocated once per column when the table is opened.

In some cases, it may be desirable to store binary data such as media
files in `BLOB' or `TEXT' columns. You may find MySQL's string handling
functions useful for working with such data. See *Note
string-functions::. For security and other reasons, it is usually
preferable to do so using application code rather than allowing
application users the `FILE' privilege. You can discuss specifics for
various languages and platforms in the MySQL Forums
(`http://forums.mysql.com/').


File: manual.info,  Node: enum,  Next: set,  Prev: blob,  Up: string-types

10.4.4 The `ENUM' Type
----------------------

An `ENUM' is a string object with a value chosen from a list of allowed
values that are enumerated explicitly in the column specification at
table creation time.

An enumeration value must be a quoted string literal; it may not be an
expression, even one that evaluates to a string value. For example, you
can create a table with an `ENUM' column like this:

     CREATE TABLE sizes (
         name ENUM('small', 'medium', 'large')
     );

However, this version of the previous `CREATE TABLE' statement does
_not_ work:

     CREATE TABLE sizes (
         c1 ENUM('small', CONCAT('med','ium'), 'large')
     );

You also may not employ a user variable as an enumeration value.  This
pair of statements do _not_ work:

     SET @mysize = 'medium';

     CREATE TABLE sizes (
         name ENUM('small', @mysize, 'large')
     );

If you wish to use a number as an enumeration value, you must enclose
it in quotes.

Duplicate values in the definition cause a warning, or an error if
strict SQL mode is enabled.

The value may also be the empty string (`''') or `NULL' under certain
circumstances:

   * If you insert an invalid value into an `ENUM' (that is, a string
     not present in the list of allowed values), the empty string is
     inserted instead as a special error value. This string can be
     distinguished from a `normal' empty string by the fact that this
     string has the numerical value 0. More about this later.

     If strict SQL mode is enabled, attempts to insert invalid `ENUM'
     values result in an error.

   * If an `ENUM' column is declared to allow `NULL', the `NULL' value
     is a legal value for the column, and the default value is `NULL'.
     If an `ENUM' column is declared `NOT NULL', its default value is
     the first element of the list of allowed values.

Each enumeration value has an index:

   * Values from the list of allowable elements in the column
     specification are numbered beginning with 1.

   * The index value of the empty string error value is 0. This means
     that you can use the following `SELECT' statement to find rows
     into which invalid `ENUM' values were assigned:

          mysql> SELECT * FROM TBL_NAME WHERE ENUM_COL=0;

   * The index of the `NULL' value is `NULL'.

   * The term `index' here refers only to position within the list of
     enumeration values. It has nothing to do with table indexes.

For example, a column specified as `ENUM('one', 'two', 'three')' can
have any of the values shown here. The index of each value is also
shown:

*Value*     *Index*
`NULL'      `NULL'
`'''        0
`'one''     1
`'two''     2
`'three''   3

An enumeration can have a maximum of 65,535 elements.

Trailing spaces are automatically deleted from `ENUM' member values in
the table definition when a table is created.

When retrieved, values stored into an `ENUM' column are displayed using
the lettercase that was used in the column definition. Note that `ENUM'
columns can be assigned a character set and collation. For binary or
case-sensitive collations, lettercase is taken into account when
assigning values to the column.

If you retrieve an `ENUM' value in a numeric context, the column
value's index is returned. For example, you can retrieve numeric values
from an `ENUM' column like this:

     mysql> SELECT ENUM_COL+0 FROM TBL_NAME;

If you store a number into an `ENUM' column, the number is treated as
the index into the possible values, and the value stored is the
enumeration member with that index.  (However, this does _not_ work with
`LOAD DATA', which treats all input as strings.) If the numeric value
is quoted, it is still interpreted as an index if there is no matching
string in the list of enumeration values. For these reasons, it is not
advisable to define an `ENUM' column with enumeration values that look
like numbers, because this can easily become confusing. For example,
the following column has enumeration members with string values of
`'0'', `'1'', and `'2'', but numeric index values of `1', `2', and `3':

     numbers ENUM('0','1','2')

If you store `2', it is interpreted as an index value, and becomes
`'1'' (the value with index 2). If you store `'2'', it matches an
enumeration value, so it is stored as `'2''. If you store `'3'', it
does not match any enumeration value, so it is treated as an index and
becomes `'2'' (the value with index 3).

     mysql> INSERT INTO t (numbers) VALUES(2),('2'),('3');
     mysql> SELECT * FROM t;
     +---------+
     | numbers |
     +---------+
     | 1       |
     | 2       |
     | 2       |
     +---------+

`ENUM' values are sorted according to the order in which the
enumeration members were listed in the column specification. (In other
words, `ENUM' values are sorted according to their index numbers.) For
example, `'a'' sorts before `'b'' for `ENUM('a', 'b')', but `'b'' sorts
before `'a'' for `ENUM('b', 'a')'. The empty string sorts before
non-empty strings, and `NULL' values sort before all other enumeration
values. To prevent unexpected results, specify the `ENUM' list in
alphabetical order. You can also use `GROUP BY CAST(col AS CHAR)' or
`GROUP BY CONCAT(col)' to make sure that the column is sorted lexically
rather than by index number.

Functions such as `SUM()' or `AVG()' that expect a numeric argument
cast the argument to a number if necessary. For `ENUM' values, the cast
operation causes the index number to be used.

If you want to determine all possible values for an `ENUM' column, use
`SHOW COLUMNS FROM TBL_NAME LIKE ENUM_COL' and parse the `ENUM'
definition in the `Type' column of the output.


File: manual.info,  Node: set,  Prev: enum,  Up: string-types

10.4.5 The `SET' Type
---------------------

A `SET' is a string object that can have zero or more values, each of
which must be chosen from a list of allowed values specified when the
table is created.  `SET' column values that consist of multiple set
members are specified with members separated by commas (``,''). A
consequence of this is that `SET' member values should not themselves
contain commas.

For example, a column specified as `SET('one', 'two') NOT NULL' can
have any of these values:

     ''
     'one'
     'two'
     'one,two'

A `SET' can have a maximum of 64 different members.

Duplicate values in the definition cause a warning, or an error if
strict SQL mode is enabled.

Trailing spaces are automatically deleted from `SET' member values in
the table definition when a table is created.

When retrieved, values stored in a `SET' column are displayed using the
lettercase that was used in the column definition. Note that `SET'
columns can be assigned a character set and collation. For binary or
case-sensitive collations, lettercase is taken into account when
assigning values to the column.

MySQL stores `SET' values numerically, with the low-order bit of the
stored value corresponding to the first set member. If you retrieve a
`SET' value in a numeric context, the value retrieved has bits set
corresponding to the set members that make up the column value. For
example, you can retrieve numeric values from a `SET' column like this:

     mysql> SELECT SET_COL+0 FROM TBL_NAME;

If a number is stored into a `SET' column, the bits that are set in the
binary representation of the number determine the set members in the
column value. For a column specified as `SET('a','b','c','d')', the
members have the following decimal and binary values:

`SET'       *Decimal       *Binary Value*
*Member*    Value*         
`'a''       `1'            `0001'
`'b''       `2'            `0010'
`'c''       `4'            `0100'
`'d''       `8'            `1000'

If you assign a value of `9' to this column, that is `1001' in binary,
so the first and fourth `SET' value members `'a'' and `'d'' are selected
and the resulting value is `'a,d''.

For a value containing more than one `SET' element, it does not matter
what order the elements are listed in when you insert the value. It
also does not matter how many times a given element is listed in the
value. When the value is retrieved later, each element in the value
appears once, with elements listed according to the order in which they
were specified at table creation time. For example, suppose that a
column is specified as `SET('a','b','c','d')':

     mysql> CREATE TABLE myset (col SET('a', 'b', 'c', 'd'));

If you insert the values `'a,d'', `'d,a'', `'a,d,d'', `'a,d,a'', and
`'d,a,d'':

     mysql> INSERT INTO myset (col) VALUES
     -> ('a,d'), ('d,a'), ('a,d,a'), ('a,d,d'), ('d,a,d');
     Query OK, 5 rows affected (0.01 sec)
     Records: 5  Duplicates: 0  Warnings: 0

Then all of these values appear as `'a,d'' when retrieved:

     mysql> SELECT col FROM myset;
     +------+
     | col  |
     +------+
     | a,d  |
     | a,d  |
     | a,d  |
     | a,d  |
     | a,d  |
     +------+
     5 rows in set (0.04 sec)

If you set a `SET' column to an unsupported value, the value is ignored
and a warning is issued:

     mysql> INSERT INTO myset (col) VALUES ('a,d,d,s');
     Query OK, 1 row affected, 1 warning (0.03 sec)

     mysql> SHOW WARNINGS;
     +---------+------+------------------------------------------+
     | Level   | Code | Message                                  |
     +---------+------+------------------------------------------+
     | Warning | 1265 | Data truncated for column 'col' at row 1 |
     +---------+------+------------------------------------------+
     1 row in set (0.04 sec)

     mysql> SELECT col FROM myset;
     +------+
     | col  |
     +------+
     | a,d  |
     | a,d  |
     | a,d  |
     | a,d  |
     | a,d  |
     | a,d  |
     +------+
     6 rows in set (0.01 sec)

If strict SQL mode is enabled, attempts to insert invalid `SET' values
result in an error.

`SET' values are sorted numerically.  `NULL' values sort before
non-`NULL' `SET' values.

Functions such as `SUM()' or `AVG()' that expect a numeric argument
cast the argument to a number if necessary. For `SET' values, the cast
operation causes the numeric value to be used.

Normally, you search for `SET' values using the `FIND_IN_SET()'
function or the `LIKE' operator:

     mysql> SELECT * FROM TBL_NAME WHERE FIND_IN_SET('VALUE',SET_COL)>0;
     mysql> SELECT * FROM TBL_NAME WHERE SET_COL LIKE '%VALUE%';

The first statement finds rows where SET_COL contains the VALUE set
member. The second is similar, but not the same: It finds rows where
SET_COL contains VALUE anywhere, even as a substring of another set
member.

The following statements also are legal:

     mysql> SELECT * FROM TBL_NAME WHERE SET_COL & 1;
     mysql> SELECT * FROM TBL_NAME WHERE SET_COL = 'VAL1,VAL2';

The first of these statements looks for values containing the first set
member. The second looks for an exact match. Be careful with
comparisons of the second type. Comparing set values to `'VAL1,VAL2''
returns different results than comparing values to `'VAL2,VAL1''.  You
should specify the values in the same order they are listed in the
column definition.

If you want to determine all possible values for a `SET' column, use
`SHOW COLUMNS FROM TBL_NAME LIKE SET_COL' and parse the `SET'
definition in the `Type' column of the output.


File: manual.info,  Node: storage-requirements,  Next: choosing-types,  Prev: string-types,  Up: data-types

10.5 Data Type Storage Requirements
===================================

The storage requirements for each of the data types supported by MySQL
are listed here by category.

The maximum size of a row in a MySQL table is 65,535 bytes. Each `BLOB'
and `TEXT' column accounts for only nine to twelve bytes toward this
size. This limitation may be shared by other storage engines as well.

*Important*:

For tables using the `NDBCLUSTER' storage engine, there is the factor
of _4-byte alignment_ to be taken into account when calculating storage
requirements. This means that all `NDB' data storage is done in
multiples of 4 bytes. Thus, a column value that would take 15 bytes in
a table using a storage engine other than `NDB' requires 16 bytes in an
`NDB' table. This requirement applies in addition to any other
considerations that are discussed in this section. For example, in
`NDBCLUSTER' tables, the `TINYINT', `SMALLINT', `MEDIUMINT', and
`INTEGER' (`INT') column types each require 4 bytes storage per record
due to the alignment factor.

In addition, when calculating storage requirements for Cluster tables,
you must remember that every table using the `NDBCLUSTER' storage
engine requires a primary key; if no primary key is defined by the
user, then a `hidden' primary key will be created by `NDB'. This hidden
primary key consumes 31-35 bytes per table record.

You may find the `ndb_size.pl' utility to be useful for estimating
`NDB' storage requirements.  This Perl script connects to a current
MySQL (non-Cluster) database and creates a report on how much space
that database would require if it used the `NDBCLUSTER' storage engine.
See *Note mysql-cluster-utilities-ndb-size::, for more information.

*Storage Requirements for Numeric Types*

*Data Type*                   *Storage Required*
`TINYINT'                     1 byte
`SMALLINT'                    2 bytes
`MEDIUMINT'                   3 bytes
`INT', `INTEGER'              4 bytes
`BIGINT'                      8 bytes
`FLOAT(P)'                    4 bytes if 0 <= P <= 24, 8 bytes if 25 <=
                              P <= 53
`FLOAT'                       4 bytes
`DOUBLE [PRECISION]', `REAL'  8 bytes
`DECIMAL(M,D)',               Varies; see following discussion
`NUMERIC(M,D)'                
`BIT(M)'                      approximately (M+7)/8 bytes

Values for `DECIMAL' (and `NUMERIC') columns are represented using a
binary format that packs nine decimal (base 10) digits into four bytes.
Storage for the integer and fractional parts of each value are
determined separately. Each multiple of nine digits requires four
bytes, and the `leftover' digits require some fraction of four bytes.
The storage required for excess digits is given by the following table:

*Leftover Digits*  *Number of Bytes*
0                  0
1                  1
2                  1
3                  2
4                  2
5                  3
6                  3
7                  4
8                  4

*Storage Requirements for Date and Time Types*

*Data Type*                   *Storage Required*
`DATE'                        3 bytes
`TIME'                        3 bytes
`DATETIME'                    8 bytes
`TIMESTAMP'                   4 bytes
`YEAR'                        1 byte

The storage requirements shown in the table arise from the way that
MySQL represents temporal values:

   * `DATE': A three-byte integer packed as `DD' + `MM'x32 +
     `YYYY'x16x32

   * `TIME': A three-byte integer packed as `DD'x24x3600 + `HH'x3600 +
     `MM'x60 + `SS'

   * `DATETIME': Eight bytes:

        * A four-byte integer packed as `YYYY'x10000 + `MM'x100 + `DD'

        * A four-byte integer packed as `HH'x10000 + `MM'x100 + `SS'

   * `TIMESTAMP': A four-byte integer representing seconds UTC since
     the epoch (`'1970-01-01 00:00:00'' UTC)

   * `YEAR': A one-byte integer

*Storage Requirements for String Types*

In the following table, M represents the declared column length in
characters for non-binary string types and bytes for binary string
types.  L represents the actual length in bytes of a given string value.

*Data Type*                   *Storage Required*
`CHAR(M)'                     M x W bytes, 0 `<= M <=' 255, where W is
                              the number of bytes required for the
                              maximum-length character in the character
                              set
`BINARY(M)'                   M bytes, 0 `<= M <=' 255
`VARCHAR(M)', `VARBINARY(M)'  L + 1 bytes if column values require 0 -
                              255 bytes, L + 2 bytes if values may
                              require more than 255 bytes
`TINYBLOB', `TINYTEXT'        L + 1 bytes, where L < 2^8
`BLOB', `TEXT'                L + 2 bytes, where L < 2^16
`MEDIUMBLOB', `MEDIUMTEXT'    L + 3 bytes, where L < 2^24
`LONGBLOB', `LONGTEXT'        L + 4 bytes, where L < 2^32
`ENUM('VALUE1','VALUE2',...)' 1 or 2 bytes, depending on the number of
                              enumeration values (65,535 values maximum)
`SET('VALUE1','VALUE2',...)'  1, 2, 3, 4, or 8 bytes, depending on the
                              number of set members (64 members maximum)

Variable-length string types are stored using a length prefix plus
data. The length prefix requires from one to four bytes depending on
the data type, and the value of the prefix is L (the byte length of the
string). For example, storage for a `MEDIUMTEXT' value requires L bytes
to store the value plus three bytes to store the length of the value.

To calculate the number of bytes used to store a particular `CHAR',
`VARCHAR', or `TEXT' column value, you must take into account the
character set used for that column and whether the value contains
multi-byte characters. In particular, when using the `utf8' Unicode
character set, you must keep in mind that not all `utf8' characters use
the same number of bytes and can require up to three bytes per
character.  For a breakdown of the storage used for different
categories of `utf8' characters, see *Note charset-unicode::.

`VARCHAR', `VARBINARY', and the `BLOB' and `TEXT' types are
variable-length types. For each, the storage requirements depend on
these factors:

   * The actual length of the column value

   * The column's maximum possible length

   * The character set used for the column, because some character sets
     contain multi-byte characters

For example, a `VARCHAR(255)' column can hold a string with a maximum
length of 255 characters. Assuming that the column uses the `latin1'
character set (one byte per character), the actual storage required is
the length of the string (L), plus one byte to record the length of the
string. For the string `'abcd'', L is 4 and the storage requirement is
five bytes. If the same column is instead declared to use the `ucs2'
double-byte character set, the storage requirement is 10 bytes: The
length of `'abcd'' is eight bytes and the column requires two bytes to
store lengths because the maximum length is greater than 255 (up to 510
bytes).

*Note*:

The effective maximum number of _bytes_ that can be stored in a
`VARCHAR' or `VARBINARY' column is subject to the maximum row size of
65,535 bytes, which is shared among all columns. For a `VARCHAR' column
that stores multi-byte characters, the effective maximum number of
_characters_ is less. For example, `utf8' characters can require up to
three bytes per character, so a `VARCHAR' column that uses the `utf8'
character set can be declared to be a maximum of 21,844 characters.

The `NDBCLUSTER' storage engine in MySQL 5.1 supports variable-width
columns. This means that a `VARCHAR' column in a MySQL Cluster table
requires the same amount of storage as it would using any other storage
engine, with the exception that such values are 4-byte aligned. Thus,
the string `'abcd'' stored in a `VARCHAR(50)' column using the `latin1'
character set requires 8 bytes (rather than 6 bytes for the same column
value in a `MyISAM' table). This represents a change in behavior from
earlier versions of `NDBCLUSTER', where a `VARCHAR(50)' column would
require 52 bytes storage per record regardless of the length of the
string being stored.

`TEXT' and `BLOB' columns are implemented differently in the NDB
Cluster storage engine, wherein each row in a `TEXT' column is made up
of two separate parts. One of these is of fixed size (256 bytes), and is
actually stored in the original table. The other consists of any data
in excess of 256 bytes, which is stored in a hidden table.  The rows in
this second table are always 2,000 bytes long. This means that the size
of a `TEXT' column is 256 if SIZE <= 256 (where SIZE represents the
size of the row); otherwise, the size is 256 + SIZE + (2000 - (SIZE -
256) % 2000).

The size of an `ENUM' object is determined by the number of different
enumeration values. One byte is used for enumerations with up to 255
possible values. Two bytes are used for enumerations having between 256
and 65,535 possible values.  See *Note enum::.

The size of a `SET' object is determined by the number of different set
members. If the set size is N, the object occupies `(N+7)/8' bytes,
rounded up to 1, 2, 3, 4, or 8 bytes. A `SET' can have a maximum of 64
members. See *Note set::.


File: manual.info,  Node: choosing-types,  Next: other-vendor-data-types,  Prev: storage-requirements,  Up: data-types

10.6 Choosing the Right Type for a Column
=========================================

For optimum storage, you should try to use the most precise type in all
cases. For example, if an integer column is used for values in the
range from `1' to `99999', `MEDIUMINT UNSIGNED' is the best type. Of
the types that represent all the required values, this type uses the
least amount of storage.

All basic calculations (`+', `-', `*', and `/') with `DECIMAL' columns
are done with precision of 65 decimal (base 10) digits. See *Note
numeric-type-overview::.

If accuracy is not too important or if speed is the highest priority,
the `DOUBLE' type may be good enough.  For high precision, you can
always convert to a fixed-point type stored in a `BIGINT'. This allows
you to do all calculations with 64-bit integers and then convert
results back to floating-point values as necessary.

`PROCEDURE ANALYSE' can be used to obtain suggestions for optimal
column data types. For more information, see *Note procedure-analyse::.


File: manual.info,  Node: other-vendor-data-types,  Prev: choosing-types,  Up: data-types

10.7 Using Data Types from Other Database Engines
=================================================

To facilitate the use of code written for SQL implementations from
other vendors, MySQL maps data types as shown in the following table.
These mappings make it easier to import table definitions from other
database systems into MySQL:

*Other Vendor Type*       *MySQL Type*
`BOOL'                    `TINYINT'
`BOOLEAN'                 `TINYINT'
`CHARACTER VARYING(M)'    `VARCHAR(M)'
`FIXED'                   `DECIMAL'
`FLOAT4'                  `FLOAT'
`FLOAT8'                  `DOUBLE'
`INT1'                    `TINYINT'
`INT2'                    `SMALLINT'
`INT3'                    `MEDIUMINT'
`INT4'                    `INT'
`INT8'                    `BIGINT'
`LONG VARBINARY'          `MEDIUMBLOB'
`LONG VARCHAR'            `MEDIUMTEXT'
`LONG'                    `MEDIUMTEXT'
`MIDDLEINT'               `MEDIUMINT'
`NUMERIC'                 `DECIMAL'

Data type mapping occurs at table creation time, after which the
original type specifications are discarded. If you create a table with
types used by other vendors and then issue a `DESCRIBE TBL_NAME'
statement, MySQL reports the table structure using the equivalent MySQL
types. For example:

     mysql> CREATE TABLE t (a BOOL, b FLOAT8, c LONG VARCHAR, d NUMERIC);
     Query OK, 0 rows affected (0.00 sec)

     mysql> DESCRIBE t;
     +-------+---------------+------+-----+---------+-------+
     | Field | Type          | Null | Key | Default | Extra |
     +-------+---------------+------+-----+---------+-------+
     | a     | tinyint(1)    | YES  |     | NULL    |       |
     | b     | double        | YES  |     | NULL    |       |
     | c     | mediumtext    | YES  |     | NULL    |       |
     | d     | decimal(10,0) | YES  |     | NULL    |       |
     +-------+---------------+------+-----+---------+-------+
     4 rows in set (0.01 sec)


File: manual.info,  Node: functions,  Next: sql-syntax,  Prev: data-types,  Up: Top

11 Functions and Operators
**************************

* Menu:

* func-op-summary-ref::          Operator and Function Reference
* non-typed-operators::          Operators
* control-flow-functions::       Control Flow Functions
* string-functions::             String Functions
* numeric-functions::            Numeric Functions
* date-and-time-functions::      Date and Time Functions
* mysql-calendar::               What Calendar Is Used By MySQL?
* fulltext-search::              Full-Text Search Functions
* cast-functions::               Cast Functions and Operators
* xml-functions::                XML Functions
* other-functions::              Other Functions
* group-by-functions-and-modifiers::  Functions and Modifiers for Use with `GROUP BY' Clauses

Expressions can be used at several points in SQL statements, such as in
the `ORDER BY' or `HAVING' clauses of `SELECT' statements, in the
`WHERE' clause of a `SELECT', `DELETE', or `UPDATE' statement, or in
`SET' statements. Expressions can be written using literal values,
column values, `NULL', built-in functions, stored functions,
user-defined functions, and operators. This chapter describes the
functions and operators that are allowed for writing expressions in
MySQL. Instructions for writing stored functions and user-defined
functions are given in *Note stored-procedures::, and *Note
adding-functions::. See *Note function-resolution::, for the rules
describing how the server interprets references to different kinds of
functions.

An expression that contains `NULL' always produces a `NULL' value
unless otherwise indicated in the documentation for a particular
function or operator.

*Note*:

By default, there must be no whitespace between a function name and the
parenthesis following it. This helps the MySQL parser distinguish
between function calls and references to tables or columns that happen
to have the same name as a function. However, spaces around function
arguments are permitted.

You can tell the MySQL server to accept spaces after function names by
starting it with the `--sql-mode=IGNORE_SPACE' option. (See *Note
server-sql-mode::.) Individual client programs can request this
behavior by using the `CLIENT_IGNORE_SPACE' option for *Note
`mysql_real_connect()': mysql-real-connect. In either case, all
function names become reserved words.

For the sake of brevity, most examples in this chapter display the
output from the `mysql' program in abbreviated form. Rather than
showing examples in this format:

     mysql> SELECT MOD(29,9);
     +-----------+
     | mod(29,9) |
     +-----------+
     |         2 |
     +-----------+
     1 rows in set (0.00 sec)

This format is used instead:

     mysql> SELECT MOD(29,9);
             -> 2


File: manual.info,  Node: func-op-summary-ref,  Next: non-typed-operators,  Prev: functions,  Up: functions

11.1 Operator and Function Reference
====================================

*Note*:

This table is part of an ongoing process to expand and simplify the
information provided on these elements. Further improvements to the
table, and corresponding descriptions will be applied over the coming
months.

*Name*                        *Description*
`ABS()'                       Return the absolute value
`ACOS()'                      Return the arc cosine
`ADDDATE()'(v4.1.1)           Add dates
`ADDTIME()'(v4.1.1)           Add time
`AES_DECRYPT()'               Decrypt using AES
`AES_ENCRYPT()'               Encrypt using AES
`AND', `&&'                   Logical AND
`ASCII()'                     Return numeric value of left-most character
`ASIN()'                      Return the arc sine
`ATAN2()', `ATAN()'           Return the arc tangent of the two arguments
`ATAN()'                      Return the arc tangent
`AVG()'                       Return the average value of the argument
`BENCHMARK()'                 Repeatedly execute an expression
`BETWEEN ... AND ... '        Check whether a value is within a range of
                              values
`BIN()'                       Return a string representation of the
                              argument
`BINARY'                      Cast a string to a binary string
`BIT_AND()'                   Return bitwise and
`BIT_COUNT()'                 Return the number of bits that are set
`BIT_LENGTH()'                Return length of argument in bits
`BIT_OR()'                    Return bitwise or
`BIT_XOR()'(v4.1.1)           Return bitwise xor
`&'                           Bitwise AND
`~'                           Invert bits
`|'                           Bitwise OR
`^'                           Bitwise XOR
`CASE'                        Case operator
`CAST()'                      Cast a value as a certain type
`CEIL()'                      Return the smallest integer value not less
                              than  the argument
`CEILING()'                   Return the smallest integer value not less
                              than  the argument
`CHAR_LENGTH()'               Return number of characters in argument
`CHAR()'                      Return the character for each integer
                              passed
`CHARACTER_LENGTH()'          A synonym for CHAR_LENGTH()
`CHARSET()'(v4.1.0)           Return the character set of the argument
`COALESCE()'                  Return the first non-NULL argument
`COERCIBILITY()'(v4.1.1)      Return the collation coercibility value of
                              the string  argument
`COLLATION()'(v4.1.0)         Return the collation of the string argument
`COMPRESS()'(v4.1.1)          Return result as a binary string
`CONCAT_WS()'                 Return concatenate with  separator
`CONCAT()'                    Return concatenated string
`CONNECTION_ID()'             Return the connection ID (thread ID)   for
                              the connection
`CONV()'                      Convert numbers between different number
                              bases
`CONVERT_TZ()'(v4.1.3)        Convert from one timezone to another
`Convert()'                   Cast a value as a certain type
`COS()'                       Return the cosine
`COT()'                       Return the cotangent
`COUNT(DISTINCT)'             Return the count of a number of different
                              values
`COUNT()'                     Return a count of the number of rows
                              returned
`CRC32()'(v4.1.0)             Compute a cyclic redundancy check value
`CURDATE()'                   Return the current date
`CURRENT_DATE()',             Synonyms for CURDATE()
`CURRENT_DATE'                
`CURRENT_TIME()',             Synonyms for CURTIME()
`CURRENT_TIME'                
`CURRENT_TIMESTAMP()',        Synonyms for NOW()
`CURRENT_TIMESTAMP'           
`CURRENT_USER()',             Return the username and hostname
`CURRENT_USER'                combination
`CURTIME()'                   Return the current time
`DATABASE()'                  Return the default (current) database name
`DATE_ADD()'                  Add two dates
`DATE_FORMAT()'               Format date as specified
`DATE_SUB()'                  Subtract two dates
`DATE()'(v4.1.1)              Extract the date part of a date or
                              datetime expression
`DATEDIFF()'(v4.1.1)          Subtract two dates
`DAY()'(v4.1.1)               Synonym for DAYOFMONTH()
`DAYNAME()'(v4.1.21)          Return the name of the weekday
`DAYOFMONTH()'                Return the day of the month (1-31)
`DAYOFWEEK()'                 Return the weekday index of the argument
`DAYOFYEAR()'                 Return the day of the year (1-366)
`DECODE()'                    Decodes a string encrypted using ENCODE()
`DEFAULT()'                   Return the default value for a table column
`DEGREES()'                   Convert radians to degrees
`DES_DECRYPT()'               Decrypt a string
`DES_ENCRYPT()'               Encrypt a string
`DIV'(v4.1.0)                 Integer division
`/'                           Division operator
`ELT()'                       Return string at index number
`ENCODE()'                    Encode a string
`ENCRYPT()'                   Encrypt a string
`<=>'                         NULL-safe equal to operator
`='                           Equal operator
`EXP()'                       Raise to the power of
`EXPORT_SET()'                Return a string such that for every bit
                              set in the value  bits, you get an on
                              string and for every unset bit, you get an
                              off string
`EXTRACT'                     Extract part of a date
`ExtractValue()'(v5.1.5)      Extracts a value from an XML string using
                              XPath notation
`FIELD()'                     Return the index (position) of the first
                              argument  in the subsequent arguments
`FIND_IN_SET()'               Return the index position of  the first
                              argument within the second argument
`FLOOR()'                     Return the largest integer value not
                              greater than  the argument
`FORMAT()'                    Return a number formatted to specified
                              number of decimal places
`FOUND_ROWS()'                For a SELECT with a LIMIT clause, the
                              number of rows that would be returned were
                              there no LIMIT clause
`FROM_DAYS()'                 Convert a day number to a date
`FROM_UNIXTIME()'             Format UNIX timestamp as a date
`GET_FORMAT()'(v4.1.1)        Return a date format string
`GET_LOCK()'                  Get a named lock
`>='                          Greater than or equal operator
`>'                           Greater than operator
`GREATEST()'                  Return the largest argument
`GROUP_CONCAT()'(v4.1)        Return a concatenated string
`HEX()'                       Return a hexadecimal representation of a
                              decimal or string value
`HOUR()'                      Extract the hour
`IF()'                        If/else construct
`IFNULL()'                    Null if/else construct
`IN()'                        Check whether a value is within a set of
                              values
`INET_ATON()'                 Return the numeric value of an IP address
`INET_NTOA()'                 Return the IP address from a numeric value
`INSERT()'                    Insert a substring at the specified
                              position up to  the specified number of
                              characters
`INSTR()'                     Return the index of the first occurrence
                              of substring
`INTERVAL()'                  Return the index of the argument   that is
                              less than the first argument
`IS_FREE_LOCK()'              Checks whether the named lock  is free
`IS NOT NULL'                 NOT NULL value test
`IS NOT'                      Test a value against a boolean
`IS NULL'                     NULL value test
`IS_USED_LOCK()'(v4.1.0)      Checks whether the named lock is in use.
                              Return connection identifier if true.
`IS'                          Test a value against a boolean
`ISNULL()'                    Test whether the argument is NULL
`LAST_DAY'(v4.1.1)            Return the last day of the month for the
                              argument
`LAST_INSERT_ID()'            Value of the AUTOINCREMENT column   for
                              the last INSERT
`LCASE()'                     Synonym for LOWER()
`LEAST()'                     Return the smallest argument
`<<'                          Left shift
`LEFT()'                      Return the leftmost number of characters
                              as specified
`LENGTH()'                    Return the length of a string in bytes
`<='                          Less than or equal operator
`<'                           Less than operator
`LIKE'                        Simple pattern matching
`LN()'                        Return the natural logarithm of the
                              argument
`LOAD_FILE()'                 Load the named file
`LOCALTIME()', `LOCALTIME'    Synonym for NOW()
`LOCALTIMESTAMP',             Synonym for NOW()
`LOCALTIMESTAMP()'(v4.0.6)    
`LOCATE()'                    Return the position of the first
                              occurrence  of substring
`LOG10()'                     Return the base-10 logarithm of the
                              argument
`LOG2()'                      Return the base-2 logarithm of the argument
`LOG()'                       Return the natural logarithm of the first
                              argument
`LOWER()'                     Return the argument in lowercase
`LPAD()'                      Return the string argument, left-padded
                              with the specified string
`LTRIM()'                     Remove leading spaces
`MAKE_SET()'                  Return a set of comma-separated strings
                              that have the corresponding bit in bits set
`MAKEDATE()'(v4.1.1)          Create a date from the year and day of year
`MAKETIME'(v4.1.1)            MAKETIME()
`MASTER_POS_WAIT()'           Block until the slave has read and
                              applied all updates up to the specified
                              position
`MATCH'                       Perform full-text search
`MAX()'                       Return the maximum value
`MD5()'                       Calculate MD5 checksum
`MICROSECOND()'(v4.1.1)       Return the microseconds from argument
`MID()'                       Return a substring starting from the
                              specified position
`MIN()'                       Return the minimum value
`-'                           Minus operator
`MINUTE()'                    Return the minute from the argument
`MOD()'                       Return the remainder
`%'                           Modulo operator
`MONTH()'                     Return the month from the date passed
`MONTHNAME()'(v4.1.21)        Return the name of the month
`NAME_CONST()'(v5.0.12)       Causes the column to have the given name
`NOT BETWEEN ... AND ...'     Check whether a value is not within a
                              range of values
`!=', `<>'                    Not equal operator
`NOT IN()'                    Check whether a value is not within a set
                              of values
`NOT LIKE'                    Negation of simple pattern matching
`NOT REGEXP'                  Negation of REGEXP
`NOT', `!'                    Negates value
`NOW()'                       Return the current date and time
`NULLIF()'                    Return NULL if expr1 = expr2
`OCT()'                       Return an octal representation of a
                              decimal  number
`OCTET_LENGTH()'              A synonym for LENGTH()
`OLD_PASSWORD()'(v4.1)        Return the value of the  old (pre-4.1)
                              implementation of PASSWORD
`||', `OR'                    Logical OR
`ORD()'                       Return character code for leftmost
                              character of the  argument
`PASSWORD()'                  Calculate and return a password string
`PERIOD_ADD()'                Add a period to a year-month
`PERIOD_DIFF()'               Return the number of months between periods
`PI()'                        Return the value of pi
`+'                           Addition operator
`POSITION()'                  A synonym for LOCATE()
`POW()'                       Return the argument raised to the
                              specified power
`POWER()'                     Return the argument raised to the
                              specified power
*Note `PROCEDURE ANALYSE()':  Analyze the results of a query
procedure-analyse.            
`QUARTER()'                   Return the quarter from a date argument
`QUOTE()'                     Escape the argument for use in an SQL
                              statement
`RADIANS()'                   Return argument converted to radians
`RAND()'                      Return a random floating-point value
`REGEXP'                      Pattern matching using regular expressions
`RELEASE_LOCK()'              Releases the named lock
`REPEAT()'                    Repeat a string the specified number of
                              times
`REPLACE()'                   Replace occurrences of a specified string
`REVERSE()'                   Reverse the characters in a string
`>>'                          Right shift
`RIGHT()'                     Return the specified rightmost number of
                              characters
`RLIKE'                       Synonym for REGEXP
`ROUND()'                     Round the argument
`ROW_COUNT()'(v5.0.1)         The number of rows  updated
`RPAD()'                      Append string the specified number of times
`RTRIM()'                     Remove trailing spaces
`SCHEMA()'(v5.0.2)            A synonym for DATABASE()
`SEC_TO_TIME()'               Converts seconds to 'HH:MM:SS' format
`SECOND()'                    Return the second (0-59)
`SESSION_USER()'              Synonym for USER()
`SHA1()', `SHA()'             Calculate an SHA-1 160-bit checksum
`SIGN()'                      Return the sign of the argument
`SIN()'                       Return the sine of the argument
`SLEEP()'(v5.0.12)            Sleep for a number of seconds
`SOUNDEX()'                   Return a soundex string
`SOUNDS LIKE'(v4.1.0)         Compare sounds
`SPACE()'                     Return a string of the specified number of
                              spaces
`SQRT()'                      Return the square root of the argument
`STD()'                       Return the population standard deviation
`STDDEV_POP()'(v5.0.3)        Return the population standard deviation
`STDDEV_SAMP()'(v5.0.3)       Return the sample standard deviation
`STDDEV()'                    Return the population standard deviation
`STR_TO_DATE()'(v4.1.1)       Convert a string to a date
`STRCMP()'                    Compare two strings
`SUBDATE()'                   When invoked with three arguments a
                              synonym for DATE_SUB()
`SUBSTR()'                    Return the substring as specified
`SUBSTRING_INDEX()'           Return a substring from a  string before
                              the specified number of occurrences of the
                              delimiter
`SUBSTRING()'                 Return the substring as specified
`SUBTIME()'(v4.1.1)           Subtract times
`SUM()'                       Return the sum
`SYSDATE()'                   Return the time at which the function
                              executes
`SYSTEM_USER()'               Synonym for USER()
`TAN()'                       Return the tangent of the argument
`TIME_FORMAT()'               Format as time
`TIME_TO_SEC()'               Return the argument converted to seconds
`TIME()'(v4.1.1)              Extract the time portion of the expression
                              passed
`TIMEDIFF()'(v4.1.1)          Subtract time
`*'                           Times operator
`TIMESTAMP()'(v4.1.1)         With a single argument, this function
                              returns the date or  datetime expression.
                              With two arguments, the sum of the
                              arguments
`TIMESTAMPADD()'(v5.0.0)      Add an interval to a datetime expression
`TIMESTAMPDIFF()'(v5.0.0)     Subtract an interval from a datetime
                              expression
`TO_DAYS()'                   Return the date argument converted to days
`TRIM()'                      Remove leading and trailing spaces
`TRUNCATE()'                  Truncate to specified number of decimal
                              places
`UCASE()'                     Synonym for UPPER()
`-'                           Change the sign of the argument
`UNCOMPRESS()'(v4.1.1)        Uncompress a string compressed
`UNCOMPRESSED_LENGTH()'(v4.1.1)Return the length of a string before
                              compression
`UNHEX()'(v4.1.2)             Convert each pair of hexadecimal digits
                              to a character
`UNIX_TIMESTAMP()'            Return a UNIX timestamp
`UpdateXML()'(v5.1.5)         Return replaced XML fragment
`UPPER()'                     Convert to uppercase
`USER()'                      Return the current username and hostname
`UTC_DATE()'(v4.1.1)          Return the current UTC date
`UTC_TIME()'(v4.1.1)          Return the current UTC time
`UTC_TIMESTAMP()'(v4.1.1)     Return the current UTC date and time
`UUID_SHORT()'(v5.1.20)       Return an integer-valued universal
                              identifier
`UUID()'(v4.1.2)              Return a Universal Unique Identifier (UUID)
`VALUES()'(v4.1.1)            Defines the values to be used during an
                              INSERT
`VAR_POP()'(v5.0.3)           Return the population standard variance
`VAR_SAMP()'(v5.0.3)          Return the sample variance
`VARIANCE()'(v4.1)            Return the population standard variance
`VERSION()'                   Returns a string that indicates the MySQL
                              server version
`WEEK()'                      Return the week number
`WEEKDAY()'                   Return the weekday index
`WEEKOFYEAR()'(v4.1.1)        Return the calendar week of the date (1-53)
`XOR'                         Logical XOR
`YEAR()'                      Return the year
`YEARWEEK()'                  Return the year and week


File: manual.info,  Node: non-typed-operators,  Next: control-flow-functions,  Prev: func-op-summary-ref,  Up: functions

11.2 Operators
==============

* Menu:

* operator-precedence::          Operator Precedence
* type-conversion::              Type Conversion in Expression Evaluation
* comparison-operators::         Comparison Functions and Operators
* logical-operators::            Logical Operators

*Name*                        *Description*
`AND', `&&'                   Logical AND
`BETWEEN ... AND ... '        Check whether a value is within a range of
                              values
`BINARY'                      Cast a string to a binary string
`&'                           Bitwise AND
`~'                           Invert bits
`|'                           Bitwise OR
`^'                           Bitwise XOR
`CASE'                        Case operator
`DIV'(v4.1.0)                 Integer division
`/'                           Division operator
`<=>'                         NULL-safe equal to operator
`='                           Equal operator
`>='                          Greater than or equal operator
`>'                           Greater than operator
`IS NOT NULL'                 NOT NULL value test
`IS NOT'                      Test a value against a boolean
`IS NULL'                     NULL value test
`IS'                          Test a value against a boolean
`<<'                          Left shift
`<='                          Less than or equal operator
`<'                           Less than operator
`LIKE'                        Simple pattern matching
`-'                           Minus operator
`%'                           Modulo operator
`NOT BETWEEN ... AND ...'     Check whether a value is not within a
                              range of values
`!=', `<>'                    Not equal operator
`NOT LIKE'                    Negation of simple pattern matching
`NOT REGEXP'                  Negation of REGEXP
`NOT', `!'                    Negates value
`||', `OR'                    Logical OR
`+'                           Addition operator
`REGEXP'                      Pattern matching using regular expressions
`>>'                          Right shift
`RLIKE'                       Synonym for REGEXP
`SOUNDS LIKE'(v4.1.0)         Compare sounds
`*'                           Times operator
`-'                           Change the sign of the argument
`XOR'                         Logical XOR


File: manual.info,  Node: operator-precedence,  Next: type-conversion,  Prev: non-typed-operators,  Up: non-typed-operators

11.2.1 Operator Precedence
--------------------------

Operator precedences are shown in the following list, from highest
precedence to the lowest. Operators that are shown together on a line
have the same precedence.

     INTERVAL
     BINARY, COLLATE
     !
     - (unary minus), ~ (unary bit inversion)
     ^
     *, /, DIV, %, MOD
     -, +
     <<, >>
     &
     |
     =, <=>, >=, >, <=, <, <>, !=, IS, LIKE, REGEXP, IN
     BETWEEN, CASE, WHEN, THEN, ELSE
     NOT
     &&, AND
     XOR
     ||, OR
     :=

The `||' operator has a precedence between `^' and the unary operators
if the `PIPES_AS_CONCAT' SQL mode is enabled.

*Note*:

If the `HIGH_NOT_PRECEDENCE' SQL mode is enabled, the precedence of
`NOT' is the same as that of the `!' operator. See *Note
server-sql-mode::.

The precedence of operators determines the order of evaluation of terms
in an expression. To override this order and group terms explicitly,
use parentheses. For example:

     mysql> SELECT 1+2*3;
             -> 7
     mysql> SELECT (1+2)*3;
             -> 9


File: manual.info,  Node: type-conversion,  Next: comparison-operators,  Prev: operator-precedence,  Up: non-typed-operators

11.2.2 Type Conversion in Expression Evaluation
-----------------------------------------------

When an operator is used with operands of different types, type
conversion occurs to make the operands compatible. Some conversions
occur implicitly. For example, MySQL automatically converts numbers to
strings as necessary, and vice versa.

     mysql> SELECT 1+'1';
             -> 2
     mysql> SELECT CONCAT(2,' test');
             -> '2 test'

It is also possible to perform explicit conversions. If you want to
convert a number to a string explicitly, use the `CAST()' or `CONCAT()'
function (`CAST()' is preferable):

     mysql> SELECT 38.8, CAST(38.8 AS CHAR);
             -> 38.8, '38.8'
     mysql> SELECT 38.8, CONCAT(38.8);
             -> 38.8, '38.8'

The following rules describe how conversion occurs for comparison
operations:

   * If one or both arguments are `NULL', the result of the comparison
     is `NULL', except for the `NULL'-safe `<=>' equality comparison
     operator. For `NULL <=> NULL', the result is true.

   * If both arguments in a comparison operation are strings, they are
     compared as strings.

   * If both arguments are integers, they are compared as integers.

   * Hexadecimal values are treated as binary strings if not compared
     to a number.

   * If one of the arguments is a `TIMESTAMP' or `DATETIME' column and
     the other argument is a constant, the constant is converted to a
     timestamp before the comparison is performed. This is done to be
     more ODBC-friendly. Note that this is not done for the arguments
     to `IN()'! To be safe, always use complete datetime, date, or time
     strings when doing comparisons.

   * In all other cases, the arguments are compared as floating-point
     (real) numbers.

The following examples illustrate conversion of strings to numbers for
comparison operations:

     mysql> SELECT 1 > '6x';
             -> 0
     mysql> SELECT 7 > '6x';
             -> 1
     mysql> SELECT 0 > 'x6';
             -> 0
     mysql> SELECT 0 = 'x6';
             -> 1

Note that when you are comparing a string column with a number, MySQL
cannot use an index on the column to look up the value quickly. If
STR_COL is an indexed string column, the index cannot be used when
performing the lookup in the following statement:

     SELECT * FROM TBL_NAME WHERE STR_COL=1;

The reason for this is that there are many different strings that may
convert to the value `1', such as `'1'', `' 1'', or `'1a''.

Comparisons that use floating-point numbers (or values that are
converted to floating-point numbers) are approximate because such
numbers are inexact. This might lead to results that appear
inconsistent:

     mysql> SELECT '18015376320243458' = 18015376320243458;
             -> 1
     mysql> SELECT '18015376320243459' = 18015376320243459;
             -> 0

Such results can occur because the values are converted to
floating-point numbers, which have only 53 bits of precision and are
subject to rounding:

     mysql> SELECT '18015376320243459'+0.0;
             -> 1.8015376320243e+16

Furthermore, the conversion from string to floating-point and from
integer to floating-point do not necessarily occur the same way. The
integer may be converted to floating-point by the CPU, whereas the
string is converted digit by digit in an operation that involves
floating-point multiplications.

The results shown will vary on different systems, and can be affected
by factors such as computer architecture or the compiler version or
optimization level. One way to avoid such problems is to use `CAST()' so
that a value will not be converted implicitly to a float-point number:

     mysql> SELECT CAST('18015376320243459' AS UNSIGNED) = 18015376320243459;
             -> 1

For more information about floating-point comparisons, see *Note
problems-with-float::.


File: manual.info,  Node: comparison-operators,  Next: logical-operators,  Prev: type-conversion,  Up: non-typed-operators

11.2.3 Comparison Functions and Operators
-----------------------------------------

*Name*                        *Description*
`BETWEEN ... AND ... '        Check whether a value is within a range of
                              values
`COALESCE()'                  Return the first non-NULL argument
`<=>'                         NULL-safe equal to operator
`='                           Equal operator
`>='                          Greater than or equal operator
`>'                           Greater than operator
`GREATEST()'                  Return the largest argument
`IN()'                        Check whether a value is within a set of
                              values
`INTERVAL()'                  Return the index of the argument   that is
                              less than the first argument
`IS NOT NULL'                 NOT NULL value test
`IS NOT'                      Test a value against a boolean
`IS NULL'                     NULL value test
`IS'                          Test a value against a boolean
`ISNULL()'                    Test whether the argument is NULL
`LEAST()'                     Return the smallest argument
`<='                          Less than or equal operator
`<'                           Less than operator
`LIKE'                        Simple pattern matching
`NOT BETWEEN ... AND ...'     Check whether a value is not within a
                              range of values
`!=', `<>'                    Not equal operator
`NOT IN()'                    Check whether a value is not within a set
                              of values
`NOT LIKE'                    Negation of simple pattern matching
`SOUNDS LIKE'(v4.1.0)         Compare sounds

Comparison operations result in a value of `1' (`TRUE'), `0' (`FALSE'),
or `NULL'. These operations work for both numbers and strings. Strings
are automatically converted to numbers and numbers to strings as
necessary.

Some of the functions in this section return values other than `1'
(`TRUE'), `0' (`FALSE'), or `NULL'. For example, `LEAST()' and
`GREATEST()'. However, the value they return is based on comparison
operations performed according to the rules described in *Note
type-conversion::.

To convert a value to a specific type for comparison purposes, you can
use the `CAST()' function.  String values can be converted to a
different character set using `CONVERT()'. See *Note cast-functions::.

By default, string comparisons are not case sensitive and use the
current character set. The default is `latin1' (cp1252 West European),
which also works well for English.

   *  `='

     Equal:

          mysql> SELECT 1 = 0;
                  -> 0
          mysql> SELECT '0' = 0;
                  -> 1
          mysql> SELECT '0.0' = 0;
                  -> 1
          mysql> SELECT '0.01' = 0;
                  -> 0
          mysql> SELECT '.01' = 0.01;
                  -> 1

   *  `<=>'

     `NULL'-safe equal. This operator performs an equality comparison
     like the `=' operator, but returns `1' rather than `NULL' if both
     operands are `NULL', and `0' rather than `NULL' if one operand is
     `NULL'.

          mysql> SELECT 1 <=> 1, NULL <=> NULL, 1 <=> NULL;
                  -> 1, 1, 0
          mysql> SELECT 1 = 1, NULL = NULL, 1 = NULL;
                  -> 1, NULL, NULL

   *  `<>', `!='

     Not equal:

          mysql> SELECT '.01' <> '0.01';
                  -> 1
          mysql> SELECT .01 <> '0.01';
                  -> 0
          mysql> SELECT 'zapp' <> 'zappp';
                  -> 1

   *  `<='

     Less than or equal:

          mysql> SELECT 0.1 <= 2;
                  -> 1

   *  `<'

     Less than:

          mysql> SELECT 2 < 2;
                  -> 0

   *  `>='

     Greater than or equal:

          mysql> SELECT 2 >= 2;
                  -> 1

   *  `>'

     Greater than:

          mysql> SELECT 2 > 2;
                  -> 0

   *  `IS BOOLEAN_VALUE'

     Tests a value against a boolean value, where BOOLEAN_VALUE can be
     `TRUE', `FALSE', or `UNKNOWN'.

          mysql> SELECT 1 IS TRUE, 0 IS FALSE, NULL IS UNKNOWN;
                  -> 1, 1, 1

   *  `IS NOT BOOLEAN_VALUE'

     Tests a value against a boolean value, where BOOLEAN_VALUE can be
     `TRUE', `FALSE', or `UNKNOWN'.

          mysql> SELECT 1 IS NOT UNKNOWN, 0 IS NOT UNKNOWN, NULL IS NOT UNKNOWN;
                  -> 1, 1, 0

   *  `IS NULL'

     Tests whether a value is `NULL'.

          mysql> SELECT 1 IS NULL, 0 IS NULL, NULL IS NULL;
                  -> 0, 0, 1

     To work well with ODBC programs, MySQL supports the following
     extra features when using `IS NULL':

        * You can find the row that contains the most recent
          `AUTO_INCREMENT' value by issuing a statement of the
          following form immediately after generating the value:

               SELECT * FROM TBL_NAME WHERE AUTO_COL IS NULL

          This behavior can be disabled by setting
          `SQL_AUTO_IS_NULL=0'. See *Note server-session-variables::.

        * For `DATE' and `DATETIME' columns that are declared as `NOT
          NULL', you can find the special date `'0000-00-00'' by using a
          statement like this:

               SELECT * FROM TBL_NAME WHERE DATE_COLUMN IS NULL

          This is needed to get some ODBC applications to work because
          ODBC does not support a `'0000-00-00'' date value.

   *  `IS NOT NULL'

     Tests whether a value is not `NULL'.

          mysql> SELECT 1 IS NOT NULL, 0 IS NOT NULL, NULL IS NOT NULL;
                  -> 1, 1, 0

   *  `EXPR BETWEEN MIN AND MAX'

     If EXPR is greater than or equal to MIN and EXPR is less than or
     equal to MAX, `BETWEEN' returns `1', otherwise it returns `0'.
     This is equivalent to the expression `(MIN <= EXPR AND EXPR <=
     MAX)' if all the arguments are of the same type. Otherwise type
     conversion takes place according to the rules described in *Note
     type-conversion::, but applied to all the three arguments.

          mysql> SELECT 1 BETWEEN 2 AND 3;
                  -> 0
          mysql> SELECT 'b' BETWEEN 'a' AND 'c';
                  -> 1
          mysql> SELECT 2 BETWEEN 2 AND '3';
                  -> 1
          mysql> SELECT 2 BETWEEN 2 AND 'x-3';
                  -> 0

     For best results when using `BETWEEN' with date or time values,
     you should use `CAST()' to explicitly convert the values to the
     desired data type. Examples: If you compare a `DATETIME' to two
     `DATE' values, convert the `DATE' values to `DATETIME' values. If
     you use a string constant such as `'2001-1-1'' in a comparison to
     a `DATE', cast the string to a `DATE'.

   *  `EXPR NOT BETWEEN MIN AND MAX'

     This is the same as `NOT (EXPR BETWEEN MIN AND MAX)'.

   *  `COALESCE(VALUE,...)'

     Returns the first non-`NULL' value in the list, or `NULL' if there
     are no non-`NULL' values.

          mysql> SELECT COALESCE(NULL,1);
                  -> 1
          mysql> SELECT COALESCE(NULL,NULL,NULL);
                  -> NULL

   *  `GREATEST(VALUE1,VALUE2,...)'

     With two or more arguments, returns the largest (maximum-valued)
     argument. The arguments are compared using the same rules as for
     `LEAST()'.

          mysql> SELECT GREATEST(2,0);
                  -> 2
          mysql> SELECT GREATEST(34.0,3.0,5.0,767.0);
                  -> 767.0
          mysql> SELECT GREATEST('B','A','C');
                  -> 'C'

     `GREATEST()' returns `NULL' if any argument is `NULL'.

   *  `EXPR IN (VALUE,...)'

     Returns `1' if EXPR is equal to any of the values in the `IN'
     list, else returns `0'. If all values are constants, they are
     evaluated according to the type of EXPR and sorted. The search for
     the item then is done using a binary search. This means `IN' is
     very quick if the `IN' value list consists entirely of constants.
     Otherwise, type conversion takes place according to the rules
     described in *Note type-conversion::, but applied to all the
     arguments.

          mysql> SELECT 2 IN (0,3,5,7);
                  -> 0
          mysql> SELECT 'wefwf' IN ('wee','wefwf','weg');
                  -> 1

     You should never mix quoted and unquoted values in an `IN' list
     because the comparison rules for quoted values (such as strings)
     and unquoted values (such as numbers) differ. Mixing types may
     therefore lead to inconsistent results. For example, do not write
     an `IN' expression like this:

          SELECT val1 FROM tbl1 WHERE val1 IN (1,2,'a');

     Instead, write it like this:

          SELECT val1 FROM tbl1 WHERE val1 IN ('1','2','a');

     The number of values in the `IN' list is only limited by the
     `max_allowed_packet' value.

     To comply with the SQL standard, `IN' returns `NULL' not only if
     the expression on the left hand side is `NULL', but also if no
     match is found in the list and one of the expressions in the list
     is `NULL'.

     `IN()' syntax can also be used to write certain types of
     subqueries. See *Note any-in-some-subqueries::.

   *  `EXPR NOT IN (VALUE,...)'

     This is the same as `NOT (EXPR IN (VALUE,...))'.

   *  `ISNULL(EXPR)'

     If EXPR is `NULL', `ISNULL()' returns `1', otherwise it returns
     `0'.

          mysql> SELECT ISNULL(1+1);
                  -> 0
          mysql> SELECT ISNULL(1/0);
                  -> 1

     `ISNULL()' can be used instead of `=' to test whether a value is
     `NULL'. (Comparing a value to `NULL' using `=' always yields
     false.)

     The `ISNULL()' function shares some special behaviors with the `IS
     NULL' comparison operator. See the description of `IS NULL'.

   *  `INTERVAL(N,N1,N2,N3,...)'

     Returns `0' if N < N1, `1' if N < N2 and so on or `-1' if N is
     `NULL'. All arguments are treated as integers. It is required that
     N1 < N2 < N3 < `...' < NN for this function to work correctly.
     This is because a binary search is used (very fast).

          mysql> SELECT INTERVAL(23, 1, 15, 17, 30, 44, 200);
                  -> 3
          mysql> SELECT INTERVAL(10, 1, 10, 100, 1000);
                  -> 2
          mysql> SELECT INTERVAL(22, 23, 30, 44, 200);
                  -> 0

   *  `LEAST(VALUE1,VALUE2,...)'

     With two or more arguments, returns the smallest (minimum-valued)
     argument. The arguments are compared using the following rules:

        * If the return value is used in an `INTEGER' context or all
          arguments are integer-valued, they are compared as integers.

        * If the return value is used in a `REAL' context or all
          arguments are real-valued, they are compared as reals.

        * If any argument is a case-sensitive string, the arguments are
          compared as case-sensitive strings.

        * In all other cases, the arguments are compared as
          case-insensitive strings.

     `LEAST()' returns `NULL' if any argument is `NULL'.

          mysql> SELECT LEAST(2,0);
                  -> 0
          mysql> SELECT LEAST(34.0,3.0,5.0,767.0);
                  -> 3.0
          mysql> SELECT LEAST('B','A','C');
                  -> 'A'

     Note that the preceding conversion rules can produce strange
     results in some borderline cases:

          mysql> SELECT CAST(LEAST(3600, 9223372036854775808.0) as SIGNED);
                  -> -9223372036854775808

     This happens because MySQL reads `9223372036854775808.0' in an
     integer context. The integer representation is not good enough to
     hold the value, so it wraps to a signed integer.


File: manual.info,  Node: logical-operators,  Prev: comparison-operators,  Up: non-typed-operators

11.2.4 Logical Operators
------------------------

*Name*                        *Description*
`AND', `&&'                   Logical AND
`NOT', `!'                    Negates value
`||', `OR'                    Logical OR
`XOR'                         Logical XOR

In SQL, all logical operators evaluate to `TRUE', `FALSE', or `NULL'
(`UNKNOWN'). In MySQL, these are implemented as 1 (`TRUE'), 0
(`FALSE'), and `NULL'. Most of this is common to different SQL database
servers, although some servers may return any non-zero value for `TRUE'.

Note that MySQL evaluates any non-zero or non-`NULL' value to `TRUE'.
For example, the following statements all assess to `TRUE':

     mysql> SELECT 10 IS TRUE;
     -> 1
     mysql> SELECT -10 IS TRUE;
     -> 1
     mysql> SELECT 'string' IS NOT NULL;
     -> 1

   *  `NOT', `!'

     Logical NOT. Evaluates to `1' if the operand is `0', to `0' if the
     operand is non-zero, and `NOT NULL' returns `NULL'.

          mysql> SELECT NOT 10;
                  -> 0
          mysql> SELECT NOT 0;
                  -> 1
          mysql> SELECT NOT NULL;
                  -> NULL
          mysql> SELECT ! (1+1);
                  -> 0
          mysql> SELECT ! 1+1;
                  -> 1

     The last example produces `1' because the expression evaluates the
     same way as `(!1)+1'.

   *  `AND', `&&'

     Logical AND. Evaluates to `1' if all operands are non-zero and not
     `NULL', to `0' if one or more operands are `0', otherwise `NULL' is
     returned.

          mysql> SELECT 1 && 1;
                  -> 1
          mysql> SELECT 1 && 0;
                  -> 0
          mysql> SELECT 1 && NULL;
                  -> NULL
          mysql> SELECT 0 && NULL;
                  -> 0
          mysql> SELECT NULL && 0;
                  -> 0

   *  `OR', `||'

     Logical OR. When both operands are non-`NULL', the result is `1'
     if any operand is non-zero, and `0' otherwise. With a `NULL'
     operand, the result is `1' if the other operand is non-zero, and
     `NULL' otherwise. If both operands are `NULL', the result is
     `NULL'.

          mysql> SELECT 1 || 1;
                  -> 1
          mysql> SELECT 1 || 0;
                  -> 1
          mysql> SELECT 0 || 0;
                  -> 0
          mysql> SELECT 0 || NULL;
                  -> NULL
          mysql> SELECT 1 || NULL;
                  -> 1

   *  `XOR'

     Logical XOR. Returns `NULL' if either operand is `NULL'. For
     non-`NULL' operands, evaluates to `1' if an odd number of operands
     is non-zero, otherwise `0' is returned.

          mysql> SELECT 1 XOR 1;
                  -> 0
          mysql> SELECT 1 XOR 0;
                  -> 1
          mysql> SELECT 1 XOR NULL;
                  -> NULL
          mysql> SELECT 1 XOR 1 XOR 1;
                  -> 1

     `a XOR b' is mathematically equal to `(a AND (NOT b)) OR ((NOT a)
     and b)'.


File: manual.info,  Node: control-flow-functions,  Next: string-functions,  Prev: non-typed-operators,  Up: functions

11.3 Control Flow Functions
===========================

*Name*                        *Description*
`CASE'                        Case operator
`IF()'                        If/else construct
`IFNULL()'                    Null if/else construct
`NULLIF()'                    Return NULL if expr1 = expr2

   *  `CASE VALUE WHEN [COMPARE_VALUE] THEN RESULT [WHEN
     [COMPARE_VALUE] THEN RESULT ...] [ELSE RESULT] END'

     `CASE WHEN [CONDITION] THEN RESULT [WHEN [CONDITION] THEN RESULT
     ...] [ELSE RESULT] END'

     The first version returns the RESULT where `VALUE=COMPARE_VALUE'.
     The second version returns the result for the first condition that
     is true. If there was no matching result value, the result after
     `ELSE' is returned, or `NULL' if there is no `ELSE' part.

          mysql> SELECT CASE 1 WHEN 1 THEN 'one'
              ->     WHEN 2 THEN 'two' ELSE 'more' END;
                  -> 'one'
          mysql> SELECT CASE WHEN 1>0 THEN 'true' ELSE 'false' END;
                  -> 'true'
          mysql> SELECT CASE BINARY 'B'
              ->     WHEN 'a' THEN 1 WHEN 'b' THEN 2 END;
                  -> NULL

     The default return type of a `CASE' expression is the compatible
     aggregated type of all return values, but also depends on the
     context in which it is used. If used in a string context, the
     result is returned as a string. If used in a numeric context, then
     the result is returned as a decimal, real, or integer value.

     *Note*:

     The syntax of the `CASE' _expression_ shown here differs slightly
     from that of the SQL `CASE' _statement_ described in *Note
     case-statement::, for use inside stored routines. The `CASE'
     statement cannot have an `ELSE NULL' clause, and it is terminated
     with `END CASE' instead of `END'.

   *  `IF(EXPR1,EXPR2,EXPR3)'

     If EXPR1 is `TRUE' (`EXPR1 <> 0' and `EXPR1 <> NULL') then `IF()'
     returns EXPR2; otherwise it returns EXPR3.  `IF()' returns a
     numeric or string value, depending on the context in which it is
     used.

          mysql> SELECT IF(1>2,2,3);
                  -> 3
          mysql> SELECT IF(1<2,'yes','no');
                  -> 'yes'
          mysql> SELECT IF(STRCMP('test','test1'),'no','yes');
                  -> 'no'

     If only one of EXPR2 or EXPR3 is explicitly `NULL', the result
     type of the `IF()' function is the type of the non-`NULL'
     expression.

     EXPR1 is evaluated as an integer value, which means that if you
     are testing floating-point or string values, you should do so
     using a comparison operation.

          mysql> SELECT IF(0.1,1,0);
                  -> 0
          mysql> SELECT IF(0.1<>0,1,0);
                  -> 1

     In the first case shown, `IF(0.1)' returns `0' because `0.1' is
     converted to an integer value, resulting in a test of `IF(0)'.
     This may not be what you expect. In the second case, the
     comparison tests the original floating-point value to see whether
     it is non-zero.  The result of the comparison is used as an
     integer.

     The default return type of `IF()' (which may matter when it is
     stored into a temporary table) is calculated as follows:

     *Expression*                       *Return
                                        Value*
     EXPR2 or EXPR3 returns a string    string
     EXPR2 or EXPR3 returns a           floating-point
     floating-point value               
     EXPR2 or EXPR3 returns an integer  integer

     If EXPR2 and EXPR3 are both strings, the result is case sensitive
     if either string is case sensitive.

     *Note*:

     There is also an `IF' _statement_, which differs from the `IF()'
     _function_ described here. See *Note if-statement::.

   *  `IFNULL(EXPR1,EXPR2)'

     If EXPR1 is not `NULL', `IFNULL()' returns EXPR1; otherwise it
     returns EXPR2.  `IFNULL()' returns a numeric or string value,
     depending on the context in which it is used.

          mysql> SELECT IFNULL(1,0);
                  -> 1
          mysql> SELECT IFNULL(NULL,10);
                  -> 10
          mysql> SELECT IFNULL(1/0,10);
                  -> 10
          mysql> SELECT IFNULL(1/0,'yes');
                  -> 'yes'

     The default result value of `IFNULL(EXPR1,EXPR2)' is the more
     `general' of the two expressions, in the order `STRING', `REAL',
     or `INTEGER'. Consider the case of a table based on expressions or
     where MySQL must internally store a value returned by `IFNULL()' in
     a temporary table:

          mysql> CREATE TABLE tmp SELECT IFNULL(1,'test') AS test;
          mysql> DESCRIBE tmp;
          +-------+---------+------+-----+---------+-------+
          | Field | Type    | Null | Key | Default | Extra |
          +-------+---------+------+-----+---------+-------+
          | test  | char(4) |      |     |         |       |
          +-------+---------+------+-----+---------+-------+

     In this example, the type of the `test' column is `CHAR(4)'.

   *  `NULLIF(EXPR1,EXPR2)'

     Returns `NULL' if `EXPR1 = EXPR2' is true, otherwise returns
     EXPR1. This is the same as `CASE WHEN EXPR1 = EXPR2 THEN NULL ELSE
     EXPR1 END'.

          mysql> SELECT NULLIF(1,1);
                  -> NULL
          mysql> SELECT NULLIF(1,2);
                  -> 1

     Note that MySQL evaluates EXPR1 twice if the arguments are not
     equal.


File: manual.info,  Node: string-functions,  Next: numeric-functions,  Prev: control-flow-functions,  Up: functions

11.4 String Functions
=====================

* Menu:

* string-comparison-functions::  String Comparison Functions
* regexp::                       Regular Expressions

*Name*                        *Description*
`ASCII()'                     Return numeric value of left-most character
`BIN()'                       Return a string representation of the
                              argument
`BIT_LENGTH()'                Return length of argument in bits
`CHAR_LENGTH()'               Return number of characters in argument
`CHAR()'                      Return the character for each integer
                              passed
`CHARACTER_LENGTH()'          A synonym for CHAR_LENGTH()
`CONCAT_WS()'                 Return concatenate with  separator
`CONCAT()'                    Return concatenated string
`ELT()'                       Return string at index number
`EXPORT_SET()'                Return a string such that for every bit
                              set in the value  bits, you get an on
                              string and for every unset bit, you get an
                              off string
`FIELD()'                     Return the index (position) of the first
                              argument  in the subsequent arguments
`FIND_IN_SET()'               Return the index position of  the first
                              argument within the second argument
`FORMAT()'                    Return a number formatted to specified
                              number of decimal places
`HEX()'                       Return a hexadecimal representation of a
                              decimal or string value
`INSERT()'                    Insert a substring at the specified
                              position up to  the specified number of
                              characters
`INSTR()'                     Return the index of the first occurrence
                              of substring
`LCASE()'                     Synonym for LOWER()
`LEFT()'                      Return the leftmost number of characters
                              as specified
`LENGTH()'                    Return the length of a string in bytes
`LIKE'                        Simple pattern matching
`LOAD_FILE()'                 Load the named file
`LOCATE()'                    Return the position of the first
                              occurrence  of substring
`LOWER()'                     Return the argument in lowercase
`LPAD()'                      Return the string argument, left-padded
                              with the specified string
`LTRIM()'                     Remove leading spaces
`MAKE_SET()'                  Return a set of comma-separated strings
                              that have the corresponding bit in bits set
`MATCH'                       Perform full-text search
`MID()'                       Return a substring starting from the
                              specified position
`NOT LIKE'                    Negation of simple pattern matching
`NOT REGEXP'                  Negation of REGEXP
`OCTET_LENGTH()'              A synonym for LENGTH()
`ORD()'                       Return character code for leftmost
                              character of the  argument
`POSITION()'                  A synonym for LOCATE()
`QUOTE()'                     Escape the argument for use in an SQL
                              statement
`REGEXP'                      Pattern matching using regular expressions
`REPEAT()'                    Repeat a string the specified number of
                              times
`REPLACE()'                   Replace occurrences of a specified string
`REVERSE()'                   Reverse the characters in a string
`RIGHT()'                     Return the specified rightmost number of
                              characters
`RLIKE'                       Synonym for REGEXP
`RPAD()'                      Append string the specified number of times
`RTRIM()'                     Remove trailing spaces
`SOUNDEX()'                   Return a soundex string
`SOUNDS LIKE'(v4.1.0)         Compare sounds
`SPACE()'                     Return a string of the specified number of
                              spaces
`STRCMP()'                    Compare two strings
`SUBSTR()'                    Return the substring as specified
`SUBSTRING_INDEX()'           Return a substring from a  string before
                              the specified number of occurrences of the
                              delimiter
`SUBSTRING()'                 Return the substring as specified
`TRIM()'                      Remove leading and trailing spaces
`UCASE()'                     Synonym for UPPER()
`UNHEX()'(v4.1.2)             Convert each pair of hexadecimal digits
                              to a character
`UPPER()'                     Convert to uppercase

String-valued functions return `NULL' if the length of the result would
be greater than the value of the `max_allowed_packet' system variable.
See *Note server-parameters::.

For functions that operate on string positions, the first position is
numbered 1.

For functions that take length arguments, non-integer arguments are
rounded to the nearest integer.

   *  `ASCII(STR)'

     Returns the numeric value of the leftmost character of the string
     STR. Returns `0' if STR is the empty string. Returns `NULL' if STR
     is `NULL'.  `ASCII()' works for 8-bit characters.

          mysql> SELECT ASCII('2');
                  -> 50
          mysql> SELECT ASCII(2);
                  -> 50
          mysql> SELECT ASCII('dx');
                  -> 100

     See also the `ORD()' function.

   *  `BIN(N)'

     Returns a string representation of the binary value of N, where N
     is a longlong (`BIGINT') number. This is equivalent to
     `CONV(N,10,2)'.  Returns `NULL' if N is `NULL'.

          mysql> SELECT BIN(12);
                  -> '1100'

   *  `BIT_LENGTH(STR)'

     Returns the length of the string STR in bits.

          mysql> SELECT BIT_LENGTH('text');
                  -> 32

   *  `CHAR(N,...  [USING CHARSET_NAME])'

     `CHAR()' interprets each argument N as an integer and returns a
     string consisting of the characters given by the code values of
     those integers. `NULL' values are skipped.

          mysql> SELECT CHAR(77,121,83,81,'76');
                  -> 'MySQL'
          mysql> SELECT CHAR(77,77.3,'77.3');
                  -> 'MMM'

     `CHAR()' arguments larger than 255 are converted into multiple
     result bytes. For example, `CHAR(256)' is equivalent to
     `CHAR(1,0)', and `CHAR(256*256)' is equivalent to `CHAR(1,0,0)':

          mysql> SELECT HEX(CHAR(1,0)), HEX(CHAR(256));
          +----------------+----------------+
          | HEX(CHAR(1,0)) | HEX(CHAR(256)) |
          +----------------+----------------+
          | 0100           | 0100           |
          +----------------+----------------+
          mysql> SELECT HEX(CHAR(1,0,0)), HEX(CHAR(256*256));
          +------------------+--------------------+
          | HEX(CHAR(1,0,0)) | HEX(CHAR(256*256)) |
          +------------------+--------------------+
          | 010000           | 010000             |
          +------------------+--------------------+

     By default, `CHAR()' returns a binary string. To produce a string
     in a given character set, use the optional `USING' clause:

          mysql> SELECT CHARSET(CHAR(0x65)), CHARSET(CHAR(0x65 USING utf8));
          +---------------------+--------------------------------+
          | CHARSET(CHAR(0x65)) | CHARSET(CHAR(0x65 USING utf8)) |
          +---------------------+--------------------------------+
          | binary              | utf8                           |
          +---------------------+--------------------------------+

     If `USING' is given and the result string is illegal for the given
     character set, a warning is issued.  Also, if strict SQL mode is
     enabled, the result from `CHAR()' becomes `NULL'.

   *  `CHAR_LENGTH(STR)'

     Returns the length of the string STR, measured in characters. A
     multi-byte character counts as a single character. This means that
     for a string containing five two-byte characters, `LENGTH()'
     returns `10', whereas `CHAR_LENGTH()' returns `5'.

   *  `CHARACTER_LENGTH(STR)'

     `CHARACTER_LENGTH()' is a synonym for `CHAR_LENGTH()'.

   *  `CONCAT(STR1,STR2,...)'

     Returns the string that results from concatenating the arguments.
     May have one or more arguments. If all arguments are non-binary
     strings, the result is a non-binary string. If the arguments
     include any binary strings, the result is a binary string. A
     numeric argument is converted to its equivalent binary string
     form; if you want to avoid that, you can use an explicit type
     cast, as in this example:

          SELECT CONCAT(CAST(INT_COL AS CHAR), CHAR_COL);

     `CONCAT()' returns `NULL' if any argument is `NULL'.

          mysql> SELECT CONCAT('My', 'S', 'QL');
                  -> 'MySQL'
          mysql> SELECT CONCAT('My', NULL, 'QL');
                  -> NULL
          mysql> SELECT CONCAT(14.3);
                  -> '14.3'

   *  `CONCAT_WS(SEPARATOR,STR1,STR2,...)'

     `CONCAT_WS()' stands for Concatenate With Separator and is a
     special form of `CONCAT()'. The first argument is the separator
     for the rest of the arguments. The separator is added between the
     strings to be concatenated. The separator can be a string, as can
     the rest of the arguments. If the separator is `NULL', the result
     is `NULL'.

          mysql> SELECT CONCAT_WS(',','First name','Second name','Last Name');
                  -> 'First name,Second name,Last Name'
          mysql> SELECT CONCAT_WS(',','First name',NULL,'Last Name');
                  -> 'First name,Last Name'

     `CONCAT_WS()' does not skip empty strings. However, it does skip
     any `NULL' values after the separator argument.

   *  `ELT(N,STR1,STR2,STR3,...)'

     Returns STR1 if N = `1', STR2 if N = `2', and so on. Returns
     `NULL' if N is less than `1' or greater than the number of
     arguments.  `ELT()' is the complement of `FIELD()'.

          mysql> SELECT ELT(1, 'ej', 'Heja', 'hej', 'foo');
                  -> 'ej'
          mysql> SELECT ELT(4, 'ej', 'Heja', 'hej', 'foo');
                  -> 'foo'

   *  `EXPORT_SET(BITS,ON,OFF[,SEPARATOR[,NUMBER_OF_BITS]])'

     Returns a string such that for every bit set in the value BITS,
     you get an ON string and for every bit not set in the value, you
     get an OFF string. Bits in BITS are examined from right to left
     (from low-order to high-order bits).  Strings are added to the
     result from left to right, separated by the SEPARATOR string (the
     default being the comma character ``,''). The number of bits
     examined is given by NUMBER_OF_BITS (defaults to 64).

          mysql> SELECT EXPORT_SET(5,'Y','N',',',4);
                  -> 'Y,N,Y,N'
          mysql> SELECT EXPORT_SET(6,'1','0',',',10);
                  -> '0,1,1,0,0,0,0,0,0,0'

   *  `FIELD(STR,STR1,STR2,STR3,...)'

     Returns the index (position) of STR in the STR1, STR2, STR3, `...'
     list.  Returns `0' if STR is not found.

     If all arguments to `FIELD()' are strings, all arguments are
     compared as strings. If all arguments are numbers, they are
     compared as numbers.  Otherwise, the arguments are compared as
     double.

     If STR is `NULL', the return value is `0' because `NULL' fails
     equality comparison with any value. `FIELD()' is the complement of
     `ELT()'.

          mysql> SELECT FIELD('ej', 'Hej', 'ej', 'Heja', 'hej', 'foo');
                  -> 2
          mysql> SELECT FIELD('fo', 'Hej', 'ej', 'Heja', 'hej', 'foo');
                  -> 0

   *  `FIND_IN_SET(STR,STRLIST)'

     Returns a value in the range of 1 to N if the string STR is in the
     string list STRLIST consisting of N substrings. A string list is a
     string composed of substrings separated by ``,'' characters. If
     the first argument is a constant string and the second is a column
     of type `SET', the `FIND_IN_SET()' function is optimized to use
     bit arithmetic. Returns `0' if STR is not in STRLIST or if STRLIST
     is the empty string.  Returns `NULL' if either argument is `NULL'.
     This function does not work properly if the first argument
     contains a comma (``,'') character.

          mysql> SELECT FIND_IN_SET('b','a,b,c,d');
                  -> 2

   *  `FORMAT(X,D)'

     Formats the number X to a format like `'#,###,###.##'', rounded to
     D decimal places, and returns the result as a string. If D is `0',
     the result has no decimal point or fractional part.

          mysql> SELECT FORMAT(12332.123456, 4);
                  -> '12,332.1235'
          mysql> SELECT FORMAT(12332.1,4);
                  -> '12,332.1000'
          mysql> SELECT FORMAT(12332.2,0);
                  -> '12,332'

   *  `HEX(N_OR_S)'

     If N_OR_S is a number, returns a string representation of the
     hexadecimal value of N, where N is a longlong (`BIGINT') number.
     This is equivalent to `CONV(N,10,16)'.

     If N_OR_S is a string, returns a hexadecimal string representation
     of N_OR_S where each character in N_OR_S is converted to two
     hexadecimal digits. The inverse of this operation is performed by
     the `UNHEX()' function.

          mysql> SELECT HEX(255);
                  -> 'FF'
          mysql> SELECT 0x616263;
                  -> 'abc'
          mysql> SELECT HEX('abc');
                  -> 616263

   *  `INSERT(STR,POS,LEN,NEWSTR)'

     Returns the string STR, with the substring beginning at position
     POS and LEN characters long replaced by the string NEWSTR. Returns
     the original string if POS is not within the length of the string.
     Replaces the rest of the string from position POS if LEN is not
     within the length of the rest of the string. Returns `NULL' if any
     argument is `NULL'.

          mysql> SELECT INSERT('Quadratic', 3, 4, 'What');
                  -> 'QuWhattic'
          mysql> SELECT INSERT('Quadratic', -1, 4, 'What');
                  -> 'Quadratic'
          mysql> SELECT INSERT('Quadratic', 3, 100, 'What');
                  -> 'QuWhat'

     This function is multi-byte safe.

   *  `INSTR(STR,SUBSTR)'

     Returns the position of the first occurrence of substring SUBSTR
     in string STR. This is the same as the two-argument form of
     `LOCATE()', except that the order of the arguments is reversed.

          mysql> SELECT INSTR('foobarbar', 'bar');
                  -> 4
          mysql> SELECT INSTR('xbar', 'foobar');
                  -> 0

     This function is multi-byte safe, and is case sensitive only if at
     least one argument is a binary string.

   *  `LCASE(STR)'

     `LCASE()' is a synonym for `LOWER()'.

   *  `LEFT(STR,LEN)'

     Returns the leftmost LEN characters from the string STR, or `NULL'
     if any argument is `NULL'.

          mysql> SELECT LEFT('foobarbar', 5);
                  -> 'fooba'

   *  `LENGTH(STR)'

     Returns the length of the string STR, measured in bytes. A
     multi-byte character counts as multiple bytes. This means that for
     a string containing five two-byte characters, `LENGTH()' returns
     `10', whereas `CHAR_LENGTH()' returns `5'.

          mysql> SELECT LENGTH('text');
                  -> 4

   *  `LOAD_FILE(FILE_NAME)'

     Reads the file and returns the file contents as a string. To use
     this function, the file must be located on the server host, you
     must specify the full pathname to the file, and you must have the
     `FILE' privilege. The file must be readable by all and its size
     less than `max_allowed_packet' bytes.

     If the file does not exist or cannot be read because one of the
     preceding conditions is not satisfied, the function returns `NULL'.

     As of MySQL 5.1.6, the `character_set_filesystem' system variable
     controls interpretation of filenames that are given as literal
     strings.

          mysql> UPDATE t
                      SET blob_col=LOAD_FILE('/tmp/picture')
                      WHERE id=1;

   *  `LOCATE(SUBSTR,STR)', `LOCATE(SUBSTR,STR,POS)'

     The first syntax returns the position of the first occurrence of
     substring SUBSTR in string STR. The second syntax returns the
     position of the first occurrence of substring SUBSTR in string
     STR, starting at position POS. Returns `0' if SUBSTR is not in STR.

          mysql> SELECT LOCATE('bar', 'foobarbar');
                  -> 4
          mysql> SELECT LOCATE('xbar', 'foobar');
                  -> 0
          mysql> SELECT LOCATE('bar', 'foobarbar', 5);
                  -> 7

     This function is multi-byte safe, and is case-sensitive only if at
     least one argument is a binary string.

   *  `LOWER(STR)'

     Returns the string STR with all characters changed to lowercase
     according to the current character set mapping. The default is
     `latin1' (cp1252 West European).

          mysql> SELECT LOWER('QUADRATICALLY');
                  -> 'quadratically'

     `LOWER()' (and `UPPER()') are ineffective when applied to binary
     strings (`BINARY', `VARBINARY', `BLOB'). To perform lettercase
     conversion, convert the string to a non-binary string:

          mysql> SET @str = BINARY 'New York';
          mysql> SELECT LOWER(@str), LOWER(CONVERT(@str USING latin1));
          +-------------+-----------------------------------+
          | LOWER(@str) | LOWER(CONVERT(@str USING latin1)) |
          +-------------+-----------------------------------+
          | New York    | new york                          |
          +-------------+-----------------------------------+

     This function is multi-byte safe.

   *  `LPAD(STR,LEN,PADSTR)'

     Returns the string STR, left-padded with the string PADSTR to a
     length of LEN characters. If STR is longer than LEN, the return
     value is shortened to LEN characters.

          mysql> SELECT LPAD('hi',4,'??');
                  -> '??hi'
          mysql> SELECT LPAD('hi',1,'??');
                  -> 'h'

   *  `LTRIM(STR)'

     Returns the string STR with leading space characters removed.

          mysql> SELECT LTRIM('  barbar');
                  -> 'barbar'

     This function is multi-byte safe.

   *  `MAKE_SET(BITS,STR1,STR2,...)'

     Returns a set value (a string containing substrings separated by
     ``,'' characters) consisting of the strings that have the
     corresponding bit in BITS set.  STR1 corresponds to bit 0, STR2 to
     bit 1, and so on.  `NULL' values in STR1, STR2, `...' are not
     appended to the result.

          mysql> SELECT MAKE_SET(1,'a','b','c');
                  -> 'a'
          mysql> SELECT MAKE_SET(1 | 4,'hello','nice','world');
                  -> 'hello,world'
          mysql> SELECT MAKE_SET(1 | 4,'hello','nice',NULL,'world');
                  -> 'hello'
          mysql> SELECT MAKE_SET(0,'a','b','c');
                  -> ''

   *  `MID(STR,POS,LEN)'

     `MID(STR,POS,LEN)' is a synonym for `SUBSTRING(STR,POS,LEN)'.

   *  `OCTET_LENGTH(STR)'

     `OCTET_LENGTH()' is a synonym for `LENGTH()'.

   *  `ORD(STR)'

     If the leftmost character of the string STR is a multi-byte
     character, returns the code for that character, calculated from the
     numeric values of its constituent bytes using this formula:

            (1st byte code)
          + (2nd byte code x 256)
          + (3rd byte code x 256^2) ...

     If the leftmost character is not a multi-byte character, `ORD()'
     returns the same value as the `ASCII()' function.

          mysql> SELECT ORD('2');
                  -> 50

   *  `POSITION(SUBSTR IN STR)'

     `POSITION(SUBSTR IN STR)' is a synonym for `LOCATE(SUBSTR,STR)'.

   *  `QUOTE(STR)'

     Quotes a string to produce a result that can be used as a properly
     escaped data value in an SQL statement. The string is returned
     enclosed by single quotes and with each instance of single quote
     (``'''), backslash (``\''), ASCII `NUL', and Control-Z preceded by
     a backslash.  If the argument is `NULL', the return value is the
     word `NULL' without enclosing single quotes.

          mysql> SELECT QUOTE('Don\'t!');
                  -> 'Don\'t!'
          mysql> SELECT QUOTE(NULL);
                  -> NULL

   *  `REPEAT(STR,COUNT)'

     Returns a string consisting of the string STR repeated COUNT
     times. If COUNT is less than 1, returns an empty string. Returns
     `NULL' if STR or COUNT are `NULL'.

          mysql> SELECT REPEAT('MySQL', 3);
                  -> 'MySQLMySQLMySQL'

   *  `REPLACE(STR,FROM_STR,TO_STR)'

     Returns the string STR with all occurrences of the string FROM_STR
     replaced by the string TO_STR.  `REPLACE()' performs a
     case-sensitive match when searching for FROM_STR.

          mysql> SELECT REPLACE('www.mysql.com', 'w', 'Ww');
                  -> 'WwWwWw.mysql.com'

     This function is multi-byte safe.

   *  `REVERSE(STR)'

     Returns the string STR with the order of the characters reversed.

          mysql> SELECT REVERSE('abc');
                  -> 'cba'

     This function is multi-byte safe.

   *  `RIGHT(STR,LEN)'

     Returns the rightmost LEN characters from the string STR, or
     `NULL' if any argument is `NULL'.

          mysql> SELECT RIGHT('foobarbar', 4);
                  -> 'rbar'

     This function is multi-byte safe.

   *  `RPAD(STR,LEN,PADSTR)'

     Returns the string STR, right-padded with the string PADSTR to a
     length of LEN characters. If STR is longer than LEN, the return
     value is shortened to LEN characters.

          mysql> SELECT RPAD('hi',5,'?');
                  -> 'hi???'
          mysql> SELECT RPAD('hi',1,'?');
                  -> 'h'

     This function is multi-byte safe.

   *  `RTRIM(STR)'

     Returns the string STR with trailing space characters removed.

          mysql> SELECT RTRIM('barbar   ');
                  -> 'barbar'

     This function is multi-byte safe.

   *  `SOUNDEX(STR)'

     Returns a soundex string from STR.  Two strings that sound almost
     the same should have identical soundex strings. A standard soundex
     string is four characters long, but the `SOUNDEX()' function
     returns an arbitrarily long string. You can use `SUBSTRING()' on
     the result to get a standard soundex string. All non-alphabetic
     characters in STR are ignored. All international alphabetic
     characters outside the A-Z range are treated as vowels.

     *Important*:

     When using `SOUNDEX()', you should be aware of the following
     limitations:

        * This function, as currently implemented, is intended to work
          well with strings that are in the English language only.
          Strings in other languages may not produce reliable results.

        * This function is not guaranteed to provide consistent results
          with strings that use multi-byte character sets, including
          `utf-8'.

          We hope to remove these limitations in a future release.  See
          Bug#22638 (http://bugs.mysql.com/22638) for more information.

          mysql> SELECT SOUNDEX('Hello');
                  -> 'H400'
          mysql> SELECT SOUNDEX('Quadratically');
                  -> 'Q36324'

     *Note*:

     This function implements the original Soundex algorithm, not the
     more popular enhanced version (also described by D.  Knuth). The
     difference is that original version discards vowels first and
     duplicates second, whereas the enhanced version discards
     duplicates first and vowels second.

   *  `EXPR1 SOUNDS LIKE EXPR2'

     This is the same as `SOUNDEX(EXPR1) = SOUNDEX(EXPR2)'.

   *  `SPACE(N)'

     Returns a string consisting of N space characters.

          mysql> SELECT SPACE(6);
                  -> '      '

   *  `SUBSTR(STR,POS)', `SUBSTR(STR FROM POS)', `SUBSTR(STR,POS,LEN)',
     `SUBSTR(STR FROM POS FOR LEN)'

     `SUBSTR()' is a synonym for `SUBSTRING()'.

   *  `SUBSTRING(STR,POS)', `SUBSTRING(STR FROM POS)',
     `SUBSTRING(STR,POS,LEN)', `SUBSTRING(STR FROM POS FOR LEN)'

     The forms without a LEN argument return a substring from string STR
     starting at position POS. The forms with a LEN argument return a
     substring LEN characters long from string STR, starting at position
     POS. The forms that use `FROM' are standard SQL syntax. It is also
     possible to use a negative value for POS. In this case, the
     beginning of the substring is POS characters from the end of the
     string, rather than the beginning. A negative value may be used
     for POS in any of the forms of this function.

     For all forms of `SUBSTRING()', the position of the first
     character in the string from which the substring is to be
     extracted is reckoned as `1'.

          mysql> SELECT SUBSTRING('Quadratically',5);
                  -> 'ratically'
          mysql> SELECT SUBSTRING('foobarbar' FROM 4);
                  -> 'barbar'
          mysql> SELECT SUBSTRING('Quadratically',5,6);
                  -> 'ratica'
          mysql> SELECT SUBSTRING('Sakila', -3);
                  -> 'ila'
          mysql> SELECT SUBSTRING('Sakila', -5, 3);
                  -> 'aki'
          mysql> SELECT SUBSTRING('Sakila' FROM -4 FOR 2);
                  -> 'ki'

     This function is multi-byte safe.

     If LEN is less than 1, the result is the empty string.

   *  `SUBSTRING_INDEX(STR,DELIM,COUNT)'

     Returns the substring from string STR before COUNT occurrences of
     the delimiter DELIM. If COUNT is positive, everything to the left
     of the final delimiter (counting from the left) is returned. If
     COUNT is negative, everything to the right of the final delimiter
     (counting from the right) is returned.  `SUBSTRING_INDEX()'
     performs a case-sensitive match when searching for DELIM.

          mysql> SELECT SUBSTRING_INDEX('www.mysql.com', '.', 2);
                  -> 'www.mysql'
          mysql> SELECT SUBSTRING_INDEX('www.mysql.com', '.', -2);
                  -> 'mysql.com'

     This function is multi-byte safe.

   *  `TRIM([{BOTH | LEADING | TRAILING} [REMSTR] FROM] STR)',
     `TRIM([REMSTR FROM] STR)'

     Returns the string STR with all REMSTR prefixes or suffixes
     removed. If none of the specifiers `BOTH', `LEADING', or
     `TRAILING' is given, `BOTH' is assumed.  REMSTR is optional and,
     if not specified, spaces are removed.

          mysql> SELECT TRIM('  bar   ');
                  -> 'bar'
          mysql> SELECT TRIM(LEADING 'x' FROM 'xxxbarxxx');
                  -> 'barxxx'
          mysql> SELECT TRIM(BOTH 'x' FROM 'xxxbarxxx');
                  -> 'bar'
          mysql> SELECT TRIM(TRAILING 'xyz' FROM 'barxxyz');
                  -> 'barx'

     This function is multi-byte safe.

   *  `UCASE(STR)'

     `UCASE()' is a synonym for `UPPER()'.

   *  `UNHEX(STR)'

     Performs the inverse operation of `HEX(STR)'.  That is, it
     interprets each pair of hexadecimal digits in the argument as a
     number and converts it to the character represented by the number.
     The resulting characters are returned as a binary string.

          mysql> SELECT UNHEX('4D7953514C');
                  -> 'MySQL'
          mysql> SELECT 0x4D7953514C;
                  -> 'MySQL'
          mysql> SELECT UNHEX(HEX('string'));
                  -> 'string'
          mysql> SELECT HEX(UNHEX('1267'));
                  -> '1267'

     The characters in the argument string must be legal hexadecimal
     digits: `'0'' ..  `'9'', `'A'' ..  `'F'', `'a'' ..  `'f''. If
     `UNHEX()' encounters any non-hexadecimal digits in the argument,
     it returns `NULL':

          mysql> SELECT UNHEX('GG');
          +-------------+
          | UNHEX('GG') |
          +-------------+
          | NULL        |
          +-------------+

     A `NULL' result can occur if the argument to `UNHEX()' is a
     `BINARY' column, because values are padded with 0x00 bytes when
     stored but those bytes are not stripped on retrieval. For example
     `'aa'' is stored into a `CHAR(3)' column as `'aa '' and retrieved
     as `'aa'' (with the trailing pad space stripped), so `UNHEX()' for
     the column value returns `'A''. By contrast `'aa'' is stored into a
     `BINARY(3)' column as `'aa\0'' and retrieved as `'aa\0'' (with the
     trailing pad `0x00' byte not stripped).  `'\0'' is not a legal
     hexadecimal digit, so `UNHEX()' for the column value returns
     `NULL'.

   *  `UPPER(STR)'

     Returns the string STR with all characters changed to uppercase
     according to the current character set mapping. The default is
     `latin1' (cp1252 West European).

          mysql> SELECT UPPER('Hej');
                  -> 'HEJ'

     `UPPER()' is ineffective when applied to binary strings (`BINARY',
     `VARBINARY', `BLOB'). The description of `LOWER()' shows how to
     perform lettercase conversion of binary strings.

     This function is multi-byte safe.


File: manual.info,  Node: string-comparison-functions,  Next: regexp,  Prev: string-functions,  Up: string-functions

11.4.1 String Comparison Functions
----------------------------------

*Name*                        *Description*
`LIKE'                        Simple pattern matching
`NOT LIKE'                    Negation of simple pattern matching
`SOUNDS LIKE'(v4.1.0)         Compare sounds

If a string function is given a binary string as an argument, the
resulting string is also a binary string. A number converted to a
string is treated as a binary string. This affects only comparisons.

Normally, if any expression in a string comparison is case sensitive,
the comparison is performed in case-sensitive fashion.

   *  `EXPR LIKE PAT [ESCAPE 'ESCAPE_CHAR']'

     Pattern matching using SQL simple regular expression comparison.
     Returns `1' (`TRUE') or `0' (`FALSE'). If either EXPR or PAT is
     `NULL', the result is `NULL'.

     The pattern need not be a literal string. For example, it can be
     specified as a string expression or table column.

     Per the SQL standard, `LIKE' performs matching on a per-character
     basis, thus it can produce results different from the `='
     comparison operator:

          mysql> SELECT 'a"' LIKE 'ae' COLLATE latin1_german2_ci;
          +-----------------------------------------+
          | 'a"' LIKE 'ae' COLLATE latin1_german2_ci |
          +-----------------------------------------+
          |                                       0 |
          +-----------------------------------------+
          mysql> SELECT 'a"' = 'ae' COLLATE latin1_german2_ci;
          +--------------------------------------+
          | 'a"' = 'ae' COLLATE latin1_german2_ci |
          +--------------------------------------+
          |                                    1 |
          +--------------------------------------+

     In particular, trailing spaces are significant, which is not true
     for `CHAR' or `VARCHAR' comparisons performed with the `='
     operator:

          mysql> SELECT 'a' = 'a ', 'a' LIKE 'a ';
          +------------+---------------+
          | 'a' = 'a ' | 'a' LIKE 'a ' |
          +------------+---------------+
          |          1 |             0 |
          +------------+---------------+
          1 row in set (0.00 sec)

     With `LIKE' you can use the following two wildcard characters in
     the pattern:

     *Character*   *Description*
     `%'           Matches any number of characters, even zero characters
     `_'           Matches exactly one character

          mysql> SELECT 'David!' LIKE 'David_';
                  -> 1
          mysql> SELECT 'David!' LIKE '%D%v%';
                  -> 1

     To test for literal instances of a wildcard character, precede it
     by the escape character. If you do not specify the `ESCAPE'
     character, ``\'' is assumed.

     *String*      *Description*
     `\%'          Matches one ``%'' character
     `\_'          Matches one ``_'' character

          mysql> SELECT 'David!' LIKE 'David\_';
                  -> 0
          mysql> SELECT 'David_' LIKE 'David\_';
                  -> 1

     To specify a different escape character, use the `ESCAPE' clause:

          mysql> SELECT 'David_' LIKE 'David|_' ESCAPE '|';
                  -> 1

     The escape sequence should be empty or one character long.  As of
     MySQL 5.1.2, if the `NO_BACKSLASH_ESCAPES' SQL mode is enabled,
     the sequence cannot be empty.

     The following two statements illustrate that string comparisons
     are not case sensitive unless one of the operands is a binary
     string:

          mysql> SELECT 'abc' LIKE 'ABC';
                  -> 1
          mysql> SELECT 'abc' LIKE BINARY 'ABC';
                  -> 0

     In MySQL, `LIKE' is allowed on numeric expressions. (This is an
     extension to the standard SQL `LIKE'.)

          mysql> SELECT 10 LIKE '1%';
                  -> 1

     *Note*:

     Because MySQL uses C escape syntax in strings (for example, ``\n''
     to represent a newline character), you must double any ``\'' that
     you use in `LIKE' strings. For example, to search for ``\n'',
     specify it as ``\\n''. To search for ``\'', specify it as
     ``\\\\''; this is because the backslashes are stripped once by the
     parser and again when the pattern match is made, leaving a single
     backslash to be matched against. (Exception: At the end of the
     pattern string, backslash can be specified as ``\\''. At the end
     of the string, backslash stands for itself because there is
     nothing following to escape.)

   *  `EXPR NOT LIKE PAT [ESCAPE 'ESCAPE_CHAR']'

     This is the same as `NOT (EXPR LIKE PAT [ESCAPE 'ESCAPE_CHAR'])'.

     *Note*:

     Aggregate queries involving `NOT LIKE' comparisons with columns
     containing `NULL' may yield unexpected results. For example,
     consider the following table and data:

          CREATE TABLE foo (bar VARCHAR(10));

          INSERT INTO foo VALUES (NULL), (NULL);

     The query `SELECT COUNT(*) FROM foo WHERE bar LIKE '%baz%';'
     returns `0'. You might assume that `SELECT COUNT(*) FROM foo WHERE
     bar NOT LIKE '%baz%';' would return `2'. However, this is not the
     case: The second query returns `0'. This is because `NULL NOT LIKE
     EXPR' always returns `NULL', regardless of the value of EXPR. The
     same is true for aggregate queries involving `NULL' and
     comparisons using `NOT RLIKE' or `NOT REGEXP'. In such cases, you
     must test explicitly for `NOT NULL' using `OR' (and not `AND'), as
     shown here:

          SELECT COUNT(*) FROM foo WHERE bar NOT LIKE '%baz%' OR bar IS NULL;

   *  `EXPR NOT REGEXP PAT', `EXPR NOT RLIKE PAT'

     This is the same as `NOT (EXPR REGEXP PAT)'.

   *  `EXPR REGEXP PAT', `EXPR RLIKE PAT'

     Performs a pattern match of a string expression EXPR against a
     pattern PAT. The pattern can be an extended regular expression.
     The syntax for regular expressions is discussed in *Note regexp::.
     Returns `1' if EXPR matches PAT; otherwise it returns `0'. If
     either EXPR or PAT is `NULL', the result is `NULL'.  `RLIKE' is a
     synonym for `REGEXP', provided for `mSQL' compatibility.

     The pattern need not be a literal string. For example, it can be
     specified as a string expression or table column.

     *Note*:

     Because MySQL uses the C escape syntax in strings (for example,
     ``\n'' to represent the newline character), you must double any
     ``\'' that you use in your `REGEXP' strings.

     `REGEXP' is not case sensitive, except when used with binary
     strings.

          mysql> SELECT 'Monty!' REGEXP 'm%y%%';
                  -> 0
          mysql> SELECT 'Monty!' REGEXP '.*';
                  -> 1
          mysql> SELECT 'new*\n*line' REGEXP 'new\\*.\\*line';
                  -> 1
          mysql> SELECT 'a' REGEXP 'A', 'a' REGEXP BINARY 'A';
                  -> 1  0
          mysql> SELECT 'a' REGEXP '^[a-d]';
                  -> 1

     `REGEXP' and `RLIKE' use the current character set when deciding
     the type of a character. The default is `latin1' (cp1252 West
     European).

     *Warning*:

     The `REGEXP' and `RLIKE' operators work in byte-wise fashion, so
     they are not multi-byte safe and may produce unexpected results
     with multi-byte character sets. In addition, these operators
     compare characters by their byte values and accented characters
     may not compare as equal even if a given collation treats them as
     equal.

   *  `STRCMP(EXPR1,EXPR2)'

     `STRCMP()' returns `0' if the strings are the same, `-1' if the
     first argument is smaller than the second according to the current
     sort order, and `1' otherwise.

          mysql> SELECT STRCMP('text', 'text2');
                  -> -1
          mysql> SELECT STRCMP('text2', 'text');
                  -> 1
          mysql> SELECT STRCMP('text', 'text');
                  -> 0

     `STRCMP()' uses the current character set when performing
     comparisons. This makes the default comparison behavior case
     insensitive unless one or both of the operands are binary strings.


File: manual.info,  Node: regexp,  Prev: string-comparison-functions,  Up: string-functions

11.4.2 Regular Expressions
--------------------------

*Name*                        *Description*
`NOT REGEXP'                  Negation of REGEXP
`REGEXP'                      Pattern matching using regular expressions
`RLIKE'                       Synonym for REGEXP

A regular expression is a powerful way of specifying a pattern for a
complex search.

MySQL uses Henry Spencer's implementation of regular expressions, which
is aimed at conformance with POSIX 1003.2.  See *Note credits::. MySQL
uses the extended version to support pattern-matching operations
performed with the `REGEXP' operator in SQL statements. See *Note
pattern-matching::, and *Note string-comparison-functions::.

This section is a summary, with examples, of the special characters and
constructs that can be used in MySQL for `REGEXP' operations. It does
not contain all the details that can be found in Henry Spencer's
`regex(7)' manual page. That manual page is included in MySQL source
distributions, in the `regex.7' file under the `regex' directory.

A regular expression describes a set of strings. The simplest regular
expression is one that has no special characters in it.  For example,
the regular expression `hello' matches `hello' and nothing else.

Non-trivial regular expressions use certain special constructs so that
they can match more than one string. For example, the regular
expression `hello|word' matches either the string `hello' or the string
`word'.

As a more complex example, the regular expression `B[an]*s' matches any
of the strings `Bananas', `Baaaaas', `Bs', and any other string
starting with a `B', ending with an `s', and containing any number of
`a' or `n' characters in between.

A regular expression for the `REGEXP' operator may use any of the
following special characters and constructs:

   * `^'

     Match the beginning of a string.

          mysql> SELECT 'fo\nfo' REGEXP '^fo$';                   -> 0
          mysql> SELECT 'fofo' REGEXP '^fo';                      -> 1

   * `$'

     Match the end of a string.

          mysql> SELECT 'fo\no' REGEXP '^fo\no$';                 -> 1
          mysql> SELECT 'fo\no' REGEXP '^fo$';                    -> 0

   * `.'

     Match any character (including carriage return and newline).

          mysql> SELECT 'fofo' REGEXP '^f.*$';                    -> 1
          mysql> SELECT 'fo\r\nfo' REGEXP '^f.*$';                -> 1

   * `a*'

     Match any sequence of zero or more `a' characters.

          mysql> SELECT 'Ban' REGEXP '^Ba*n';                     -> 1
          mysql> SELECT 'Baaan' REGEXP '^Ba*n';                   -> 1
          mysql> SELECT 'Bn' REGEXP '^Ba*n';                      -> 1

   * `a+'

     Match any sequence of one or more `a' characters.

          mysql> SELECT 'Ban' REGEXP '^Ba+n';                     -> 1
          mysql> SELECT 'Bn' REGEXP '^Ba+n';                      -> 0

   * `a?'

     Match either zero or one `a' character.

          mysql> SELECT 'Bn' REGEXP '^Ba?n';                      -> 1
          mysql> SELECT 'Ban' REGEXP '^Ba?n';                     -> 1
          mysql> SELECT 'Baan' REGEXP '^Ba?n';                    -> 0

   * `de|abc'

     Match either of the sequences `de' or `abc'.

          mysql> SELECT 'pi' REGEXP 'pi|apa';                     -> 1
          mysql> SELECT 'axe' REGEXP 'pi|apa';                    -> 0
          mysql> SELECT 'apa' REGEXP 'pi|apa';                    -> 1
          mysql> SELECT 'apa' REGEXP '^(pi|apa)$';                -> 1
          mysql> SELECT 'pi' REGEXP '^(pi|apa)$';                 -> 1
          mysql> SELECT 'pix' REGEXP '^(pi|apa)$';                -> 0

   * `(abc)*'

     Match zero or more instances of the sequence `abc'.

          mysql> SELECT 'pi' REGEXP '^(pi)*$';                    -> 1
          mysql> SELECT 'pip' REGEXP '^(pi)*$';                   -> 0
          mysql> SELECT 'pipi' REGEXP '^(pi)*$';                  -> 1

   * `{1}', `{2,3}'

     `{n}' or `{m,n}' notation provides a more general way of writing
     regular expressions that match many occurrences of the previous
     atom (or `piece') of the pattern. `m' and `n' are integers.

        * `a*'

          Can be written as `a{0,}'.

        * `a+'

          Can be written as `a{1,}'.

        * `a?'

          Can be written as `a{0,1}'.

     To be more precise, `a{n}' matches exactly `n' instances of `a'.
     `a{n,}' matches `n' or more instances of `a'.  `a{m,n}' matches `m'
     through `n' instances of `a', inclusive.

     `m' and `n' must be in the range from `0' to `RE_DUP_MAX' (default
     255), inclusive. If both `m' and `n' are given, `m' must be less
     than or equal to `n'.

          mysql> SELECT 'abcde' REGEXP 'a[bcd]{2}e';              -> 0
          mysql> SELECT 'abcde' REGEXP 'a[bcd]{3}e';              -> 1
          mysql> SELECT 'abcde' REGEXP 'a[bcd]{1,10}e';           -> 1

   * `[a-dX]', `[^a-dX]'

     Matches any character that is (or is not, if ^ is used) either
     `a', `b', `c', `d' or `X'. A `-' character between two other
     characters forms a range that matches all characters from the
     first character to the second. For example, `[0-9]' matches any
     decimal digit.  To include a literal `]' character, it must
     immediately follow the opening bracket `['.  To include a literal
     `-' character, it must be written first or last. Any character
     that does not have a defined special meaning inside a `[]' pair
     matches only itself.

          mysql> SELECT 'aXbc' REGEXP '[a-dXYZ]';                 -> 1
          mysql> SELECT 'aXbc' REGEXP '^[a-dXYZ]$';               -> 0
          mysql> SELECT 'aXbc' REGEXP '^[a-dXYZ]+$';              -> 1
          mysql> SELECT 'aXbc' REGEXP '^[^a-dXYZ]+$';             -> 0
          mysql> SELECT 'gheis' REGEXP '^[^a-dXYZ]+$';            -> 1
          mysql> SELECT 'gheisa' REGEXP '^[^a-dXYZ]+$';           -> 0

   * `[.characters.]'

     Within a bracket expression (written using `[' and `]'), matches
     the sequence of characters of that collating element.
     `characters' is either a single character or a character name like
     `newline'. The following table lists the allowable character names.

     The following table shows the allowable character names and the
     characters that they match. For characters given as numeric
     values, the values are represented in octal.

     *Name*            *Character*       *Name*            *Character*
     `NUL'             `0'               `SOH'             `001'
     `STX'             `002'             `ETX'             `003'
     `EOT'             `004'             `ENQ'             `005'
     `ACK'             `006'             `BEL'             `007'
     `alert'           `007'             `BS'              `010'
     `backspace'       `'\b''            `HT'              `011'
     `tab'             `'\t''            `LF'              `012'
     `newline'         `'\n''            `VT'              `013'
     `vertical-tab'    `'\v''            `FF'              `014'
     `form-feed'       `'\f''            `CR'              `015'
     `carriage-return' `'\r''            `SO'              `016'
     `SI'              `017'             `DLE'             `020'
     `DC1'             `021'             `DC2'             `022'
     `DC3'             `023'             `DC4'             `024'
     `NAK'             `025'             `SYN'             `026'
     `ETB'             `027'             `CAN'             `030'
     `EM'              `031'             `SUB'             `032'
     `ESC'             `033'             `IS4'             `034'
     `FS'              `034'             `IS3'             `035'
     `GS'              `035'             `IS2'             `036'
     `RS'              `036'             `IS1'             `037'
     `US'              `037'             `space'           `' ''
     `exclamation-mark'`'!''             `quotation-mark'  `'"''
     `number-sign'     `'#''             `dollar-sign'     `'$''
     `percent-sign'    `'%''             `ampersand'       `'&''
     `apostrophe'      `'\'''            `left-parenthesis'`'(''
     `right-parenthesis'`')''             `asterisk'        `'*''
     `plus-sign'       `'+''             `comma'           `',''
     `hyphen'          `'-''             `hyphen-minus'    `'-''
     `period'          `'.''             `full-stop'       `'.''
     `slash'           `'/''             `solidus'         `'/''
     `zero'            `'0''             `one'             `'1''
     `two'             `'2''             `three'           `'3''
     `four'            `'4''             `five'            `'5''
     `six'             `'6''             `seven'           `'7''
     `eight'           `'8''             `nine'            `'9''
     `colon'           `':''             `semicolon'       `';''
     `less-than-sign'  `'<''             `equals-sign'     `'=''
     `greater-than-sign'`'>''             `question-mark'   `'?''
     `commercial-at'   `'@''             `left-square-bracket'`'[''
     `backslash'       `'\\''            `reverse-solidus' `'\\''
     `right-square-bracket'`']''             `circumflex'      `'^''
     `circumflex-accent'`'^''             `underscore'      `'_''
     `low-line'        `'_''             `grave-accent'    `'`''
     `left-brace'      `'{''             `left-curly-bracket'`'{''
     `vertical-line'   `'|''             `right-brace'     `'}''
     `right-curly-bracket'`'}''             `tilde'           `'~''
     `DEL'             `177'                               

          mysql> SELECT '~' REGEXP '[[.~.]]';                     -> 1
          mysql> SELECT '~' REGEXP '[[.tilde.]]';                 -> 1

   * `[=character_class=]'

     Within a bracket expression (written using `[' and `]'),
     `[=character_class=]' represents an equivalence class. It matches
     all characters with the same collation value, including itself.
     For example, if `o' and `(+)' are the members of an equivalence
     class, then `[[=o=]]', `[[=(+)=]]', and `[o(+)]' are all
     synonymous. An equivalence class may not be used as an endpoint of
     a range.

   * `[:character_class:]'

     Within a bracket expression (written using `[' and `]'),
     `[:character_class:]' represents a character class that matches
     all characters belonging to that class. The following table lists
     the standard class names. These names stand for the character
     classes defined in the `ctype(3)' manual page. A particular locale
     may provide other class names. A character class may not be used
     as an endpoint of a range.

     `alnum' Alphanumeric characters
     `alpha' Alphabetic characters
     `blank' Whitespace characters
     `cntrl' Control characters
     `digit' Digit characters
     `graph' Graphic characters
     `lower' Lowercase alphabetic characters
     `print' Graphic or space characters
     `punct' Punctuation characters
     `space' Space, tab, newline, and carriage return
     `upper' Uppercase alphabetic characters
     `xdigit'Hexadecimal digit characters

          mysql> SELECT 'justalnums' REGEXP '[[:alnum:]]+';       -> 1
          mysql> SELECT '!!' REGEXP '[[:alnum:]]+';               -> 0

   * `[[:<:]]', `[[:>:]]'

     These markers stand for word boundaries. They match the beginning
     and end of words, respectively. A word is a sequence of word
     characters that is not preceded by or followed by word characters.
     A word character is an alphanumeric character in the `alnum' class
     or an underscore (`_').

          mysql> SELECT 'a word a' REGEXP '[[:<:]]word[[:>:]]';   -> 1
          mysql> SELECT 'a xword a' REGEXP '[[:<:]]word[[:>:]]';  -> 0

To use a literal instance of a special character in a regular
expression, precede it by two backslash (\) characters. The MySQL
parser interprets one of the backslashes, and the regular expression
library interprets the other. For example, to match the string `1+2'
that contains the special `+' character, only the last of the following
regular expressions is the correct one:

     mysql> SELECT '1+2' REGEXP '1+2';                       -> 0
     mysql> SELECT '1+2' REGEXP '1\+2';                      -> 0
     mysql> SELECT '1+2' REGEXP '1\\+2';                     -> 1


File: manual.info,  Node: numeric-functions,  Next: date-and-time-functions,  Prev: string-functions,  Up: functions

11.5 Numeric Functions
======================

* Menu:

* arithmetic-functions::         Arithmetic Operators
* mathematical-functions::       Mathematical Functions

*Name*                        *Description*
`ABS()'                       Return the absolute value
`ACOS()'                      Return the arc cosine
`ASIN()'                      Return the arc sine
`ATAN2()', `ATAN()'           Return the arc tangent of the two arguments
`ATAN()'                      Return the arc tangent
`CEIL()'                      Return the smallest integer value not less
                              than  the argument
`CEILING()'                   Return the smallest integer value not less
                              than  the argument
`CONV()'                      Convert numbers between different number
                              bases
`COS()'                       Return the cosine
`COT()'                       Return the cotangent
`CRC32()'(v4.1.0)             Compute a cyclic redundancy check value
`DEGREES()'                   Convert radians to degrees
`DIV'(v4.1.0)                 Integer division
`/'                           Division operator
`EXP()'                       Raise to the power of
`FLOOR()'                     Return the largest integer value not
                              greater than  the argument
`LN()'                        Return the natural logarithm of the
                              argument
`LOG10()'                     Return the base-10 logarithm of the
                              argument
`LOG2()'                      Return the base-2 logarithm of the argument
`LOG()'                       Return the natural logarithm of the first
                              argument
`-'                           Minus operator
`MOD()'                       Return the remainder
`%'                           Modulo operator
`OCT()'                       Return an octal representation of a
                              decimal  number
`PI()'                        Return the value of pi
`+'                           Addition operator
`POW()'                       Return the argument raised to the
                              specified power
`POWER()'                     Return the argument raised to the
                              specified power
`RADIANS()'                   Return argument converted to radians
`RAND()'                      Return a random floating-point value
`ROUND()'                     Round the argument
`SIGN()'                      Return the sign of the argument
`SIN()'                       Return the sine of the argument
`SQRT()'                      Return the square root of the argument
`TAN()'                       Return the tangent of the argument
`*'                           Times operator
`TRUNCATE()'                  Truncate to specified number of decimal
                              places
`-'                           Change the sign of the argument


File: manual.info,  Node: arithmetic-functions,  Next: mathematical-functions,  Prev: numeric-functions,  Up: numeric-functions

11.5.1 Arithmetic Operators
---------------------------

*Name*                        *Description*
`DIV'(v4.1.0)                 Integer division
`/'                           Division operator
`-'                           Minus operator
`%'                           Modulo operator
`+'                           Addition operator
`*'                           Times operator
`-'                           Change the sign of the argument

The usual arithmetic operators are available. The result is determined
according to the following rules:

   * In the case of `-', `+', and `*', the result is calculated with
     `BIGINT' (64-bit) precision if both arguments are integers.

   * If one of the arguments is an unsigned integer, and the other
     argument is also an integer, the result is an unsigned integer.

   * If any of the operands of a `+', `-', `/', `*', `%' is a real or
     string value, then the precision of the result is the precision of
     the argument with the maximum precision.

   * In division performed with `/', the scale of the result when using
     two exact values is the scale of the first argument plus the value
     of the `div_precision_increment' system variable (which is 4 by
     default). For example, the result of the expression `5.05 / 0.014'
     has a scale of six decimal places (`360.714286').

These rules are applied for each operation, such that nested
calculations imply the precision of each component. Hence, `(14620 /
9432456) / (24250 / 9432456)', would resolve first to `(0.0014) /
(0.0026)', with the final result having 8 decimal places (`0.60288653').

Because of these rules and the way they are applied, care should be
taken to ensure that components and sub-components of a calculation use
the appropriate level of precision. See *Note cast-functions::.

   *  `+'

     Addition:

          mysql> SELECT 3+5;
                  -> 8

   *  `-'

     Subtraction:

          mysql> SELECT 3-5;
                  -> -2

   *  `-'

     Unary minus. This operator changes the sign of the argument.

          mysql> SELECT - 2;
                  -> -2

     *Note*:

     If this operator is used with a `BIGINT', the return value is also
     a `BIGINT'. This means that you should avoid using `-' on integers
     that may have the value of -2^63.

   *  `*'

     Multiplication:

          mysql> SELECT 3*5;
                  -> 15
          mysql> SELECT 18014398509481984*18014398509481984.0;
                  -> 324518553658426726783156020576256.0
          mysql> SELECT 18014398509481984*18014398509481984;
                  -> 0

     The result of the last expression is incorrect because the result
     of the integer multiplication exceeds the 64-bit range of `BIGINT'
     calculations. (See *Note numeric-types::.)

   *  `/'

     Division:

          mysql> SELECT 3/5;
                  -> 0.60

     Division by zero produces a `NULL' result:

          mysql> SELECT 102/(1-1);
                  -> NULL

     A division is calculated with `BIGINT' arithmetic only if
     performed in a context where its result is converted to an integer.

   *  `DIV'

     Integer division. Similar to `FLOOR()', but is safe with `BIGINT'
     values.

          mysql> SELECT 5 DIV 2;
                  -> 2

   *  `N % M'

     Modulo operation. Returns the remainder of N divided by M. For
     more information, see the description for the `MOD()' function in
     *Note mathematical-functions::.


File: manual.info,  Node: mathematical-functions,  Prev: arithmetic-functions,  Up: numeric-functions

11.5.2 Mathematical Functions
-----------------------------

*Name*                        *Description*
`ABS()'                       Return the absolute value
`ACOS()'                      Return the arc cosine
`ASIN()'                      Return the arc sine
`ATAN2()', `ATAN()'           Return the arc tangent of the two arguments
`ATAN()'                      Return the arc tangent
`CEIL()'                      Return the smallest integer value not less
                              than  the argument
`CEILING()'                   Return the smallest integer value not less
                              than  the argument
`CONV()'                      Convert numbers between different number
                              bases
`COS()'                       Return the cosine
`COT()'                       Return the cotangent
`CRC32()'(v4.1.0)             Compute a cyclic redundancy check value
`DEGREES()'                   Convert radians to degrees
`EXP()'                       Raise to the power of
`FLOOR()'                     Return the largest integer value not
                              greater than  the argument
`LN()'                        Return the natural logarithm of the
                              argument
`LOG10()'                     Return the base-10 logarithm of the
                              argument
`LOG2()'                      Return the base-2 logarithm of the argument
`LOG()'                       Return the natural logarithm of the first
                              argument
`MOD()'                       Return the remainder
`OCT()'                       Return an octal representation of a
                              decimal  number
`PI()'                        Return the value of pi
`POW()'                       Return the argument raised to the
                              specified power
`POWER()'                     Return the argument raised to the
                              specified power
`RADIANS()'                   Return argument converted to radians
`RAND()'                      Return a random floating-point value
`ROUND()'                     Round the argument
`SIGN()'                      Return the sign of the argument
`SIN()'                       Return the sine of the argument
`SQRT()'                      Return the square root of the argument
`TAN()'                       Return the tangent of the argument
`TRUNCATE()'                  Truncate to specified number of decimal
                              places

All mathematical functions return `NULL' in the event of an error.

   *  `ABS(X)'

     Returns the absolute value of X.

          mysql> SELECT ABS(2);
                  -> 2
          mysql> SELECT ABS(-32);
                  -> 32

     This function is safe to use with `BIGINT' values.

   *  `ACOS(X)'

     Returns the arc cosine of X, that is, the value whose cosine is X.
     Returns `NULL' if X is not in the range `-1' to `1'.

          mysql> SELECT ACOS(1);
                  -> 0
          mysql> SELECT ACOS(1.0001);
                  -> NULL
          mysql> SELECT ACOS(0);
                  -> 1.5707963267949

   *  `ASIN(X)'

     Returns the arc sine of X, that is, the value whose sine is X.
     Returns `NULL' if X is not in the range `-1' to `1'.

          mysql> SELECT ASIN(0.2);
                  -> 0.20135792079033
          mysql> SELECT ASIN('foo');

          +-------------+
          | ASIN('foo') |
          +-------------+
          |           0 |
          +-------------+
          1 row in set, 1 warning (0.00 sec)

          mysql> SHOW WARNINGS;
          +---------+------+-----------------------------------------+
          | Level   | Code | Message                                 |
          +---------+------+-----------------------------------------+
          | Warning | 1292 | Truncated incorrect DOUBLE value: 'foo' |
          +---------+------+-----------------------------------------+

   *  `ATAN(X)'

     Returns the arc tangent of X, that is, the value whose tangent is
     X.

          mysql> SELECT ATAN(2);
                  -> 1.1071487177941
          mysql> SELECT ATAN(-2);
                  -> -1.1071487177941

   *  `ATAN(Y,X)', `ATAN2(Y,X)'

     Returns the arc tangent of the two variables X and Y. It is
     similar to calculating the arc tangent of `Y / X', except that the
     signs of both arguments are used to determine the quadrant of the
     result.

          mysql> SELECT ATAN(-2,2);
                  -> -0.78539816339745
          mysql> SELECT ATAN2(PI(),0);
                  -> 1.5707963267949

   *  `CEIL(X)'

     `CEIL()' is a synonym for `CEILING()'.

   *  `CEILING(X)'

     Returns the smallest integer value not less than X.

          mysql> SELECT CEILING(1.23);
                  -> 2
          mysql> SELECT CEILING(-1.23);
                  -> -1

     For exact-value numeric arguments, the return value has an
     exact-value numeric type. For string or floating-point arguments,
     the return value has a floating-point type.

   *  `CONV(N,FROM_BASE,TO_BASE)'

     Converts numbers between different number bases. Returns a string
     representation of the number N, converted from base FROM_BASE to
     base TO_BASE. Returns `NULL' if any argument is `NULL'. The
     argument N is interpreted as an integer, but may be specified as
     an integer or a string. The minimum base is `2' and the maximum
     base is `36'. If TO_BASE is a negative number, N is regarded as a
     signed number. Otherwise, N is treated as unsigned.  `CONV()'
     works with 64-bit precision.

          mysql> SELECT CONV('a',16,2);
                  -> '1010'
          mysql> SELECT CONV('6E',18,8);
                  -> '172'
          mysql> SELECT CONV(-17,10,-18);
                  -> '-H'
          mysql> SELECT CONV(10+'10'+'10'+0xa,10,10);
                  -> '40'

   *  `COS(X)'

     Returns the cosine of X, where X is given in radians.

          mysql> SELECT COS(PI());
                  -> -1

   *  `COT(X)'

     Returns the cotangent of X.

          mysql> SELECT COT(12);
                  -> -1.5726734063977
          mysql> SELECT COT(0);
                  -> NULL

   *  `CRC32(EXPR)'

     Computes a cyclic redundancy check value and returns a 32-bit
     unsigned value. The result is `NULL' if the argument is `NULL'.
     The argument is expected to be a string and (if possible) is
     treated as one if it is not.

          mysql> SELECT CRC32('MySQL');
                  -> 3259397556
          mysql> SELECT CRC32('mysql');
                  -> 2501908538

   *  `DEGREES(X)'

     Returns the argument X, converted from radians to degrees.

          mysql> SELECT DEGREES(PI());
                  -> 180
          mysql> SELECT DEGREES(PI() / 2);
                  -> 90

   *  `EXP(X)'

     Returns the value of _e_ (the base of natural logarithms) raised
     to the power of X. The inverse of this function is `LOG()' (using
     a single argument only) or `LN()'.

          mysql> SELECT EXP(2);
                  -> 7.3890560989307
          mysql> SELECT EXP(-2);
                  -> 0.13533528323661
          mysql> SELECT EXP(0);
                  -> 1

   *  `FLOOR(X)'

     Returns the largest integer value not greater than X.

          mysql> SELECT FLOOR(1.23);
                  -> 1
          mysql> SELECT FLOOR(-1.23);
                  -> -2

     For exact-value numeric arguments, the return value has an
     exact-value numeric type. For string or floating-point arguments,
     the return value has a floating-point type.

   * `FORMAT(X,D)'

     Formats the number X to a format like `'#,###,###.##'', rounded to
     D decimal places, and returns the result as a string. For details,
     see *Note string-functions::.

   * `HEX(N_or_S)'

     This function can be used to obtain a hexadecimal representation
     of a decimal number or a string; the manner in which it does so
     varies according to the argument's type. See this function's
     description in *Note string-functions::, for details.

   *  `LN(X)'

     Returns the natural logarithm of X; that is, the base-_e_
     logarithm of X. If X is less than or equal to 0, then `NULL' is
     returned.

          mysql> SELECT LN(2);
                  -> 0.69314718055995
          mysql> SELECT LN(-2);
                  -> NULL

     This function is synonymous with `LOG(X)'.  The inverse of this
     function is the `EXP()' function.

   *  `LOG(X)', `LOG(B,X)'

     If called with one parameter, this function returns the natural
     logarithm of X. If X is less than or equal to 0, then `NULL' is
     returned.

     The inverse of this function (when called with a single argument)
     is the `EXP()' function.

          mysql> SELECT LOG(2);
                  -> 0.69314718055995
          mysql> SELECT LOG(-2);
                  -> NULL

     If called with two parameters, this function returns the logarithm
     of X to the base B. If X is less than or equal to 0, or if B is
     less than or equal to 1, then `NULL' is returned.

          mysql> SELECT LOG(2,65536);
                  -> 16
          mysql> SELECT LOG(10,100);
                  -> 2
          mysql> SELECT LOG(1,100);
                  -> NULL

     `LOG(B,X)' is equivalent to `LOG(X) / LOG(B)'.

   *  `LOG2(X)'

     Returns the base-2 logarithm of `X'.

          mysql> SELECT LOG2(65536);
                  -> 16
          mysql> SELECT LOG2(-100);
                  -> NULL

     `LOG2()' is useful for finding out how many bits a number requires
     for storage. This function is equivalent to the expression `LOG(X)
     / LOG(2)'.

   *  `LOG10(X)'

     Returns the base-10 logarithm of X.

          mysql> SELECT LOG10(2);
                  -> 0.30102999566398
          mysql> SELECT LOG10(100);
                  -> 2
          mysql> SELECT LOG10(-100);
                  -> NULL

     `LOG10(X)' is equivalent to `LOG(10,X)'.

   *  `MOD(N,M)', `N % M', `N MOD M'

     Modulo operation. Returns the remainder of N divided by M.

          mysql> SELECT MOD(234, 10);
                  -> 4
          mysql> SELECT 253 % 7;
                  -> 1
          mysql> SELECT MOD(29,9);
                  -> 2
          mysql> SELECT 29 MOD 9;
                  -> 2

     This function is safe to use with `BIGINT' values.

     `MOD()' also works on values that have a fractional part and
     returns the exact remainder after division:

          mysql> SELECT MOD(34.5,3);
                  -> 1.5

     `MOD(N,0)' returns `NULL'.

   *  `OCT(N)'

     Returns a string representation of the octal value of N, where N
     is a longlong (`BIGINT') number. This is equivalent to
     `CONV(N,10,8)'.  Returns `NULL' if N is `NULL'.

          mysql> SELECT OCT(12);
                  -> '14'

   *  `PI()'

     Returns the value of π (pi). The default number of decimal places
     displayed is seven, but MySQL uses the full double-precision value
     internally.

          mysql> SELECT PI();
                  -> 3.141593
          mysql> SELECT PI()+0.000000000000000000;
                  -> 3.141592653589793116

   *  `POW(X,Y)'

     Returns the value of X raised to the power of Y.

          mysql> SELECT POW(2,2);
                  -> 4
          mysql> SELECT POW(2,-2);
                  -> 0.25

   *  `POWER(X,Y)'

     This is a synonym for `POW()'.

   *  `RADIANS(X)'

     Returns the argument X, converted from degrees to radians. (Note
     that π radians equals 180 degrees.)

          mysql> SELECT RADIANS(90);
                  -> 1.5707963267949

   *  `RAND()', `RAND(N)'

     Returns a random floating-point value V in the range `0' <= V <
     `1.0'. If a constant integer argument N is specified, it is used
     as the seed value, which produces a repeatable sequence of column
     values.

          mysql> SELECT RAND();
                  -> 0.9233482386203
          mysql> SELECT RAND(20);
                  -> 0.15888261251047
          mysql> SELECT RAND(20);
                  -> 0.15888261251047
          mysql> SELECT RAND();
                  -> 0.63553050033332
          mysql> SELECT RAND();
                  -> 0.70100469486881
          mysql> SELECT RAND(20);
                  -> 0.15888261251047

     With a constant initializer, the seed is initialized once when the
     statement is compiled, prior to execution. As of MySQL 5.1.16, if
     a non-constant initializer (such as a column name) is used as the
     argument, the seed is initialized with the value for each
     invocation of `RAND()'. (One implication of this is that for equal
     argument values, `RAND()' will return the same value each time.)
     From MySQL 5.1.3 to 5.1.15, non-constant arguments are disallowed.
     Before that, the effect of using a non-constant argument is
     undefined.

     To obtain a random integer R in the range I <= R < J, use the
     expression `FLOOR(I + RAND() * (J - I))'. For example, to obtain a
     random integer in the range the range `7' <= R < `12', you could
     use the following statement:

          SELECT FLOOR(7 + (RAND() * 5));

     You cannot use a column with `RAND()' values in an `ORDER BY'
     clause, because `ORDER BY' would evaluate the column multiple
     times.  However, you can retrieve rows in random order like this:

          mysql> SELECT * FROM TBL_NAME ORDER BY RAND();

     `ORDER BY RAND()' combined with `LIMIT' is useful for selecting a
     random sample from a set of rows:

          mysql> SELECT * FROM table1, table2 WHERE a=b AND c<d -> ORDER BY RAND() LIMIT 1000;

     Note that `RAND()' in a `WHERE' clause is re-evaluated every time
     the `WHERE' is executed.

     `RAND()' is not meant to be a perfect random generator, but
     instead is a fast way to generate _ad hoc_ random numbers which is
     portable between platforms for the same MySQL version.

   *  `ROUND(X)', `ROUND(X,D)'

     Rounds the argument X to D decimal places. The rounding algorithm
     depends on the data type of X. D defaults to 0 if not specified. D
     can be negative to cause D digits left of the decimal point of the
     value X to become zero.

          mysql> SELECT ROUND(-1.23);
                  -> -1
          mysql> SELECT ROUND(-1.58);
                  -> -2
          mysql> SELECT ROUND(1.58);
                  -> 2
          mysql> SELECT ROUND(1.298, 1);
                  -> 1.3
          mysql> SELECT ROUND(1.298, 0);
                  -> 1
          mysql> SELECT ROUND(23.298, -1);
                  -> 20

     The return type is the same type as that of the first argument
     (assuming that it is integer, double, or decimal).  This means
     that for an integer argument, the result is an integer (no decimal
     places):

          mysql> SELECT ROUND(150.000,2), ROUND(150,2);
          +------------------+--------------+
          | ROUND(150.000,2) | ROUND(150,2) |
          +------------------+--------------+
          |           150.00 |          150 |
          +------------------+--------------+

     `ROUND()' uses the following rules depending on the type of the
     first argument:

        * For exact-value numbers, `ROUND()' uses the `round half up'
          or `round toward nearest' rule: A value with a fractional
          part of .5 or greater is rounded up to the next integer if
          positive or down to the next integer if negative. (In other
          words, it is rounded away from zero.) A value with a
          fractional part less than .5 is rounded down to the next
          integer if positive or up to the next integer if negative.

        * For approximate-value numbers, the result depends on the C
          library. On many systems, this means that `ROUND()' uses the
          "round to nearest even" rule: A value with any fractional part
          is rounded to the nearest even integer.

     The following example shows how rounding differs for exact and
     approximate values:

          mysql> SELECT ROUND(2.5), ROUND(25E-1);
          +------------+--------------+
          | ROUND(2.5) | ROUND(25E-1) |
          +------------+--------------+
          | 3          |            2 |
          +------------+--------------+

     For more information, see *Note precision-math::.

   *  `SIGN(X)'

     Returns the sign of the argument as `-1', `0', or `1', depending on
     whether X is negative, zero, or positive.

          mysql> SELECT SIGN(-32);
                  -> -1
          mysql> SELECT SIGN(0);
                  -> 0
          mysql> SELECT SIGN(234);
                  -> 1

   *  `SIN(X)'

     Returns the sine of X, where X is given in radians.

          mysql> SELECT SIN(PI());
                  -> 1.2246063538224e-16
          mysql> SELECT ROUND(SIN(PI()));
                  -> 0

   *  `SQRT(X)'

     Returns the square root of a non-negative number X.

          mysql> SELECT SQRT(4);
                  -> 2
          mysql> SELECT SQRT(20);
                  -> 4.4721359549996
          mysql> SELECT SQRT(-16);
                  -> NULL

   *  `TAN(X)'

     Returns the tangent of X, where X is given in radians.

          mysql> SELECT TAN(PI());
                  -> -1.2246063538224e-16
          mysql> SELECT TAN(PI()+1);
                  -> 1.5574077246549

   *  `TRUNCATE(X,D)'

     Returns the number X, truncated to D decimal places. If D is `0',
     the result has no decimal point or fractional part.  D can be
     negative to cause D digits left of the decimal point of the value
     X to become zero.

          mysql> SELECT TRUNCATE(1.223,1);
                  -> 1.2
          mysql> SELECT TRUNCATE(1.999,1);
                  -> 1.9
          mysql> SELECT TRUNCATE(1.999,0);
                  -> 1
          mysql> SELECT TRUNCATE(-1.999,1);
                  -> -1.9
          mysql> SELECT TRUNCATE(122,-2);
                 -> 100
          mysql> SELECT TRUNCATE(10.28*100,0);
                 -> 1028

     All numbers are rounded toward zero.


File: manual.info,  Node: date-and-time-functions,  Next: mysql-calendar,  Prev: numeric-functions,  Up: functions

11.6 Date and Time Functions
============================

This section describes the functions that can be used to manipulate
temporal values. See *Note date-and-time-types::, for a description of
the range of values each date and time type has and the valid formats
in which values may be specified.

*Name*                        *Description*
`ADDDATE()'(v4.1.1)           Add dates
`ADDTIME()'(v4.1.1)           Add time
`CONVERT_TZ()'(v4.1.3)        Convert from one timezone to another
`CURDATE()'                   Return the current date
`CURRENT_DATE()',             Synonyms for CURDATE()
`CURRENT_DATE'                
`CURRENT_TIME()',             Synonyms for CURTIME()
`CURRENT_TIME'                
`CURRENT_TIMESTAMP()',        Synonyms for NOW()
`CURRENT_TIMESTAMP'           
`CURTIME()'                   Return the current time
`DATE_ADD()'                  Add two dates
`DATE_FORMAT()'               Format date as specified
`DATE_SUB()'                  Subtract two dates
`DATE()'(v4.1.1)              Extract the date part of a date or
                              datetime expression
`DATEDIFF()'(v4.1.1)          Subtract two dates
`DAY()'(v4.1.1)               Synonym for DAYOFMONTH()
`DAYNAME()'(v4.1.21)          Return the name of the weekday
`DAYOFMONTH()'                Return the day of the month (1-31)
`DAYOFWEEK()'                 Return the weekday index of the argument
`DAYOFYEAR()'                 Return the day of the year (1-366)
`EXTRACT'                     Extract part of a date
`FROM_DAYS()'                 Convert a day number to a date
`FROM_UNIXTIME()'             Format UNIX timestamp as a date
`GET_FORMAT()'(v4.1.1)        Return a date format string
`HOUR()'                      Extract the hour
`LAST_DAY'(v4.1.1)            Return the last day of the month for the
                              argument
`LOCALTIME()', `LOCALTIME'    Synonym for NOW()
`LOCALTIMESTAMP',             Synonym for NOW()
`LOCALTIMESTAMP()'(v4.0.6)    
`MAKEDATE()'(v4.1.1)          Create a date from the year and day of year
`MAKETIME'(v4.1.1)            MAKETIME()
`MICROSECOND()'(v4.1.1)       Return the microseconds from argument
`MINUTE()'                    Return the minute from the argument
`MONTH()'                     Return the month from the date passed
`MONTHNAME()'(v4.1.21)        Return the name of the month
`NOW()'                       Return the current date and time
`PERIOD_ADD()'                Add a period to a year-month
`PERIOD_DIFF()'               Return the number of months between periods
`QUARTER()'                   Return the quarter from a date argument
`SEC_TO_TIME()'               Converts seconds to 'HH:MM:SS' format
`SECOND()'                    Return the second (0-59)
`STR_TO_DATE()'(v4.1.1)       Convert a string to a date
`SUBDATE()'                   When invoked with three arguments a
                              synonym for DATE_SUB()
`SUBTIME()'(v4.1.1)           Subtract times
`SYSDATE()'                   Return the time at which the function
                              executes
`TIME_FORMAT()'               Format as time
`TIME_TO_SEC()'               Return the argument converted to seconds
`TIME()'(v4.1.1)              Extract the time portion of the expression
                              passed
`TIMEDIFF()'(v4.1.1)          Subtract time
`TIMESTAMP()'(v4.1.1)         With a single argument, this function
                              returns the date or  datetime expression.
                              With two arguments, the sum of the
                              arguments
`TIMESTAMPADD()'(v5.0.0)      Add an interval to a datetime expression
`TIMESTAMPDIFF()'(v5.0.0)     Subtract an interval from a datetime
                              expression
`TO_DAYS()'                   Return the date argument converted to days
`UNIX_TIMESTAMP()'            Return a UNIX timestamp
`UTC_DATE()'(v4.1.1)          Return the current UTC date
`UTC_TIME()'(v4.1.1)          Return the current UTC time
`UTC_TIMESTAMP()'(v4.1.1)     Return the current UTC date and time
`WEEK()'                      Return the week number
`WEEKDAY()'                   Return the weekday index
`WEEKOFYEAR()'(v4.1.1)        Return the calendar week of the date (1-53)
`YEAR()'                      Return the year
`YEARWEEK()'                  Return the year and week

Here is an example that uses date functions. The following query
selects all rows with a DATE_COL value from within the last 30 days:

     mysql> SELECT SOMETHING FROM TBL_NAME
         -> WHERE DATE_SUB(CURDATE(),INTERVAL 30 DAY) <= DATE_COL;

Note that the query also selects rows with dates that lie in the future.

Functions that expect date values usually accept datetime values and
ignore the time part. Functions that expect time values usually accept
datetime values and ignore the date part.

Functions that return the current date or time each are evaluated only
once per query at the start of query execution. This means that
multiple references to a function such as `NOW()' within a single query
always produce the same result (for our purposes a single query also
includes a call to a stored routine or trigger and all sub-routines
called by that routine/trigger). This principle also applies to
`CURDATE()', `CURTIME()', `UTC_DATE()', `UTC_TIME()',
`UTC_TIMESTAMP()', and to any of their synonyms.

The `CURRENT_TIMESTAMP()', `CURRENT_TIME()', `CURRENT_DATE()', and
`FROM_UNIXTIME()' functions return values in the connection's current
time zone, which is available as the value of the `time_zone' system
variable.  In addition, `UNIX_TIMESTAMP()' assumes that its argument is
a datetime value in the current time zone. See *Note
time-zone-support::.

Some date functions can be used with `zero' dates or incomplete dates
such as `'2001-11-00'', whereas others cannot. Functions that extract
parts of dates typically work with incomplete dates. For example:

     mysql> SELECT DAYOFMONTH('2001-11-00'), MONTH('2005-00-00');
             -> 0, 0

Other functions expect complete dates and return `NULL' for incomplete
dates. These include functions that perform date arithmetic or that map
parts of dates to names. For example:

     mysql> SELECT DATE_ADD('2006-05-00',INTERVAL 1 DAY);
             -> NULL
     mysql> SELECT DAYNAME('2006-05-00');
             -> NULL

   *  `ADDDATE(DATE,INTERVAL EXPR UNIT)', `ADDDATE(EXPR,DAYS)'

     When invoked with the `INTERVAL' form of the second argument,
     `ADDDATE()' is a synonym for `DATE_ADD()'. The related function
     `SUBDATE()' is a synonym for `DATE_SUB()'. For information on the
     `INTERVAL' UNIT argument, see the discussion for `DATE_ADD()'.

          mysql> SELECT DATE_ADD('1998-01-02', INTERVAL 31 DAY);
                  -> '1998-02-02'
          mysql> SELECT ADDDATE('1998-01-02', INTERVAL 31 DAY);
                  -> '1998-02-02'

     When invoked with the DAYS form of the second argument, MySQL
     treats it as an integer number of days to be added to EXPR.

          mysql> SELECT ADDDATE('1998-01-02', 31);
                  -> '1998-02-02'

   *  `ADDTIME(EXPR1,EXPR2)'

     `ADDTIME()' adds EXPR2 to EXPR1 and returns the result.  EXPR1 is
     a time or datetime expression, and EXPR2 is a time expression.

          mysql> SELECT ADDTIME('2007-12-31 23:59:59.999999',
              ->                '1 1:1:1.000002');
                  -> '2008-01-02 01:01:01.000001'
          mysql> SELECT ADDTIME('01:00:00.999999', '02:00:00.999998');
                  -> '03:00:01.999997'

   *  `CONVERT_TZ(DT,FROM_TZ,TO_TZ)'

     `CONVERT_TZ()' converts a datetime value DT from the time zone
     given by FROM_TZ to the time zone given by TO_TZ and returns the
     resulting value. Time zones are specified as described in *Note
     time-zone-support::. This function returns `NULL' if the arguments
     are invalid.

     If the value falls out of the supported range of the `TIMESTAMP'
     type when converted from FROM_TZ to UTC, no conversion occurs. The
     `TIMESTAMP' range is described in *Note
     date-and-time-type-overview::.

          mysql> SELECT CONVERT_TZ('2004-01-01 12:00:00','GMT','MET');
                  -> '2004-01-01 13:00:00'
          mysql> SELECT CONVERT_TZ('2004-01-01 12:00:00','+00:00','+10:00');
                  -> '2004-01-01 22:00:00'

     *Note*:

     To use named time zones such as `'MET'' or `'Europe/Moscow'', the
     time zone tables must be properly set up. See *Note
     time-zone-support::, for instructions.

     Before MySQL 5.1.17, if you intend to use `CONVERT_TZ()' while
     other tables are locked with `LOCK TABLES', you must also lock the
     `mysql.time_zone_name' table. See *Note lock-tables::.

   *  `CURDATE()'

     Returns the current date as a value in `'YYYY-MM-DD'' or `YYYYMMDD'
     format, depending on whether the function is used in a string or
     numeric context.

          mysql> SELECT CURDATE();
                  -> '2008-06-13'
          mysql> SELECT CURDATE() + 0;
                  -> 20080613

   *  `CURRENT_DATE', `CURRENT_DATE()'

     `CURRENT_DATE' and `CURRENT_DATE()' are synonyms for `CURDATE()'.

   *  `CURTIME()'

     Returns the current time as a value in `'HH:MM:SS'' or
     `HHMMSS.uuuuuu' format, depending on whether the function is used
     in a string or numeric context. The value is expressed in the
     current time zone.

          mysql> SELECT CURTIME();
                  -> '23:50:26'
          mysql> SELECT CURTIME() + 0;
                  -> 235026.000000

   *  `CURRENT_TIME', `CURRENT_TIME()'

     `CURRENT_TIME' and `CURRENT_TIME()' are synonyms for `CURTIME()'.

   *  `CURRENT_TIMESTAMP', `CURRENT_TIMESTAMP()'

     `CURRENT_TIMESTAMP' and `CURRENT_TIMESTAMP()' are synonyms for
     `NOW()'.

   *  `DATE(EXPR)'

     Extracts the date part of the date or datetime expression EXPR.

          mysql> SELECT DATE('2003-12-31 01:02:03');
                  -> '2003-12-31'

   *  `DATEDIFF(EXPR1,EXPR2)'

     `DATEDIFF()' returns EXPR1 - EXPR2 expressed as a value in days
     from one date to the other. EXPR1 and EXPR2 are date or
     date-and-time expressions. Only the date parts of the values are
     used in the calculation.

          mysql> SELECT DATEDIFF('2007-12-31 23:59:59','2007-12-30');
                  -> 1
          mysql> SELECT DATEDIFF('2010-11-30 23:59:59','2010-12-31');
                  -> -31

   *  `DATE_ADD(DATE,INTERVAL EXPR UNIT)', `DATE_SUB(DATE,INTERVAL EXPR
     UNIT)'

     These functions perform date arithmetic. The DATE argument
     specifies the starting date or datetime value.  EXPR is an
     expression specifying the interval value to be added or subtracted
     from the starting date. EXPR is a string; it may start with a
     ``-'' for negative intervals. UNIT is a keyword indicating the
     units in which the expression should be interpreted.

     The `INTERVAL' keyword and the UNIT specifier are not case
     sensitive.

     The following table shows the expected form of the EXPR argument
     for each UNIT value.

     UNIT *Value*                       *Expected* EXPR *Format*
     `MICROSECOND'                      `MICROSECONDS'
     `SECOND'                           `SECONDS'
     `MINUTE'                           `MINUTES'
     `HOUR'                             `HOURS'
     `DAY'                              `DAYS'
     `WEEK'                             `WEEKS'
     `MONTH'                            `MONTHS'
     `QUARTER'                          `QUARTERS'
     `YEAR'                             `YEARS'
     `SECOND_MICROSECOND'               `'SECONDS.MICROSECONDS''
     `MINUTE_MICROSECOND'               `'MINUTES.MICROSECONDS''
     `MINUTE_SECOND'                    `'MINUTES:SECONDS''
     `HOUR_MICROSECOND'                 `'HOURS.MICROSECONDS''
     `HOUR_SECOND'                      `'HOURS:MINUTES:SECONDS''
     `HOUR_MINUTE'                      `'HOURS:MINUTES''
     `DAY_MICROSECOND'                  `'DAYS.MICROSECONDS''
     `DAY_SECOND'                       `'DAYS HOURS:MINUTES:SECONDS''
     `DAY_MINUTE'                       `'DAYS HOURS:MINUTES''
     `DAY_HOUR'                         `'DAYS HOURS''
     `YEAR_MONTH'                       `'YEARS-MONTHS''

     The return value depends on the arguments:

        * `DATETIME' if the first argument is a `DATETIME' (or
          `TIMESTAMP') value, or if the first argument is a `DATE' and
          the UNIT value uses `HOURS', `MINUTES', or `SECONDS'.

        * String otherwise.

     To ensure that the result is `DATETIME', you can use `CAST()' to
     convert the first argument to `DATETIME'.

     MySQL allows any punctuation delimiter in the EXPR format. Those
     shown in the table are the suggested delimiters. If the DATE
     argument is a `DATE' value and your calculations involve only
     `YEAR', `MONTH', and `DAY' parts (that is, no time parts), the
     result is a `DATE' value. Otherwise, the result is a `DATETIME'
     value.

     Date arithmetic also can be performed using `INTERVAL' together
     with the `+' or `-' operator:

          `date' + INTERVAL EXPR UNIT
          `date' - INTERVAL EXPR UNIT

     `INTERVAL EXPR UNIT' is allowed on either side of the `+' operator
     if the expression on the other side is a date or datetime value.
     For the `-' operator, `INTERVAL EXPR UNIT' is allowed only on the
     right side, because it makes no sense to subtract a date or
     datetime value from an interval.

          mysql> SELECT '2008-12-31 23:59:59' + INTERVAL 1 SECOND;
                  -> '2009-01-01 00:00:00'
          mysql> SELECT INTERVAL 1 DAY + '2008-12-31';
                  -> '2009-01-01'
          mysql> SELECT '2005-01-01' - INTERVAL 1 SECOND;
                  -> '2004-12-31 23:59:59'
          mysql> SELECT DATE_ADD('2000-12-31 23:59:59',
              ->                 INTERVAL 1 SECOND);
                  -> '2001-01-01 00:00:00'
          mysql> SELECT DATE_ADD('2010-12-31 23:59:59',
              ->                 INTERVAL 1 DAY);
                  -> '2011-01-01 23:59:59'
          mysql> SELECT DATE_ADD('2100-12-31 23:59:59',
              ->                 INTERVAL '1:1' MINUTE_SECOND);
                  -> '2101-01-01 00:01:00'
          mysql> SELECT DATE_SUB('2005-01-01 00:00:00',
              ->                 INTERVAL '1 1:1:1' DAY_SECOND);
                  -> '2004-12-30 22:58:59'
          mysql> SELECT DATE_ADD('1900-01-01 00:00:00',
              ->                 INTERVAL '-1 10' DAY_HOUR);
                  -> '1899-12-30 14:00:00'
          mysql> SELECT DATE_SUB('1998-01-02', INTERVAL 31 DAY);
                  -> '1997-12-02'
          mysql> SELECT DATE_ADD('1992-12-31 23:59:59.000002',
              ->            INTERVAL '1.999999' SECOND_MICROSECOND);
                  -> '1993-01-01 00:00:01.000001'

     If you specify an interval value that is too short (does not
     include all the interval parts that would be expected from the
     UNIT keyword), MySQL assumes that you have left out the leftmost
     parts of the interval value.  For example, if you specify a UNIT
     of `DAY_SECOND', the value of EXPR is expected to have days,
     hours, minutes, and seconds parts. If you specify a value like
     `'1:10'', MySQL assumes that the days and hours parts are missing
     and the value represents minutes and seconds. In other words,
     `'1:10' DAY_SECOND' is interpreted in such a way that it is
     equivalent to `'1:10' MINUTE_SECOND'. This is analogous to the way
     that MySQL interprets `TIME' values as representing elapsed time
     rather than as a time of day.

     Because EXPR is treated as a string, be careful if you specify a
     non-string value with `INTERVAL'. For example, with an interval
     specifier of `HOUR_MINUTE', `6/4' evaluates to `1.5000' and is
     treated as 1 hour, 5000 minutes:

          mysql> SELECT 6/4;
                  -> 1.5000
          mysql> SELECT DATE_ADD('1999-01-01', INTERVAL 6/4 HOUR_MINUTE);
                  -> '1999-01-04 12:20:00'

     To ensure interpretation of the interval value as you expect, a
     `CAST()' operation may be used. To treat `6/4' as 1 hour, 5
     minutes, cast it to a `DECIMAL' value with a single fractional
     digit:

          mysql> SELECT CAST(6/4 AS DECIMAL(3,1));
                  -> 1.5
          mysql> SELECT DATE_ADD('1970-01-01 12:00:00',
              ->                 INTERVAL CAST(6/4 AS DECIMAL(3,1)) HOUR_MINUTE);
                  -> '1970-01-01 13:05:00'

     If you add to or subtract from a date value something that
     contains a time part, the result is automatically converted to a
     datetime value:

          mysql> SELECT DATE_ADD('1999-01-01', INTERVAL 1 DAY);
                  -> '1999-01-02'
          mysql> SELECT DATE_ADD('1999-01-01', INTERVAL 1 HOUR);
                  -> '1999-01-01 01:00:00'

     If you add `MONTH', `YEAR_MONTH', or `YEAR' and the resulting date
     has a day that is larger than the maximum day for the new month,
     the day is adjusted to the maximum days in the new month:

          mysql> SELECT DATE_ADD('1998-01-30', INTERVAL 1 MONTH);
                  -> '1998-02-28'

     Date arithmetic operations require complete dates and do not work
     with incomplete dates such as `'2006-07-00'' or badly malformed
     dates:

          mysql> SELECT DATE_ADD('2006-07-00', INTERVAL 1 DAY);
                  -> NULL
          mysql> SELECT '2005-03-32' + INTERVAL 1 MONTH;
                  -> NULL

   *  `DATE_FORMAT(DATE,FORMAT)'

     Formats the DATE value according to the FORMAT string.

     The following specifiers may be used in the FORMAT string. The
     ``%'' character is required before format specifier characters.

     *Specifier*   *Description*
     `%a'          Abbreviated weekday name (`Sun'..`Sat')
     `%b'          Abbreviated month name (`Jan'..`Dec')
     `%c'          Month, numeric (`0'..`12')
     `%D'          Day of the month with English suffix (`0th',
                   `1st', `2nd', `3rd', ...)
     `%d'          Day of the month, numeric (`00'..`31')
     `%e'          Day of the month, numeric (`0'..`31')
     `%f'          Microseconds (`000000'..`999999')
     `%H'          Hour (`00'..`23')
     `%h'          Hour (`01'..`12')
     `%I'          Hour (`01'..`12')
     `%i'          Minutes, numeric (`00'..`59')
     `%j'          Day of year (`001'..`366')
     `%k'          Hour (`0'..`23')
     `%l'          Hour (`1'..`12')
     `%M'          Month name (`January'..`December')
     `%m'          Month, numeric (`00'..`12')
     `%p'          `AM' or `PM'
     `%r'          Time, 12-hour (`hh:mm:ss' followed by `AM' or
                   `PM')
     `%S'          Seconds (`00'..`59')
     `%s'          Seconds (`00'..`59')
     `%T'          Time, 24-hour (`hh:mm:ss')
     `%U'          Week (`00'..`53'), where Sunday is the first
                   day of the week
     `%u'          Week (`00'..`53'), where Monday is the first
                   day of the week
     `%V'          Week (`01'..`53'), where Sunday is the first
                   day of the week; used with `%X'
     `%v'          Week (`01'..`53'), where Monday is the first
                   day of the week; used with `%x'
     `%W'          Weekday name (`Sunday'..`Saturday')
     `%w'          Day of the week (`0'=Sunday..`6'=Saturday)
     `%X'          Year for the week where Sunday is the first
                   day of the week, numeric, four digits; used
                   with `%V'
     `%x'          Year for the week, where Monday is the first
                   day of the week, numeric, four digits; used
                   with `%v'
     `%Y'          Year, numeric, four digits
     `%y'          Year, numeric (two digits)
     `%%'          A literal ``%'' character
     `%X'          X, for any `X' not listed above

     Ranges for the month and day specifiers begin with zero due to the
     fact that MySQL allows the storing of incomplete dates such as
     `'2004-00-00''.

     As of MySQL 5.1.12, the language used for day and month names and
     abbreviations is controlled by the value of the `lc_time_names'
     system variable (*Note locale-support::).

     As of MySQL 5.1.15, `DATE_FORMAT()' returns a string with a
     character set and collation given by `character_set_connection' and
     `collation_connection' so that it can return month and weekday
     names containing non-ASCII characters.  Before 5.1.15, the return
     value is a binary string.

          mysql> SELECT DATE_FORMAT('2009-10-04 22:23:00', '%W %M %Y');
                  -> 'Sunday October 2009'
          mysql> SELECT DATE_FORMAT('2007-10-04 22:23:00', '%H:%i:%s');
                  -> '22:23:00'
          mysql> SELECT DATE_FORMAT('1900-10-04 22:23:00',
              ->                 '%D %y %a %d %m %b %j');
                  -> '4th 00 Thu 04 10 Oct 277'
          mysql> SELECT DATE_FORMAT('1997-10-04 22:23:00',
              ->                 '%H %k %I %r %T %S %w');
                  -> '22 22 10 10:23:00 PM 22:23:00 00 6'
          mysql> SELECT DATE_FORMAT('1999-01-01', '%X %V');
                  -> '1998 52'
          mysql> SELECT DATE_FORMAT('2006-06-00', '%d');
                  -> '00'

   *  `DATE_SUB(DATE,INTERVAL EXPR UNIT)'

     See the description for `DATE_ADD()'.

   *  `DAY(DATE)'

     `DAY()' is a synonym for `DAYOFMONTH()'.

   *  `DAYNAME(DATE)'

     Returns the name of the weekday for DATE. As of MySQL 5.1.12, the
     language used for the name is controlled by the value of the
     `lc_time_names' system variable (*Note locale-support::).

          mysql> SELECT DAYNAME('1998-02-05');
                  -> 'Thursday'

   *  `DAYOFMONTH(DATE)'

     Returns the day of the month for DATE, in the range `1' to `31', or
     `0' for dates such as `'0000-00-00'' or `'2008-00-00'' that have a
     zero day part.

          mysql> SELECT DAYOFMONTH('1998-02-03');
                  -> 3

   *  `DAYOFWEEK(DATE)'

     Returns the weekday index for DATE (`1' = Sunday, `2' = Monday,
     ..., `7' = Saturday). These index values correspond to the ODBC
     standard.

          mysql> SELECT DAYOFWEEK('1998-02-03');
                  -> 3

   *  `DAYOFYEAR(DATE)'

     Returns the day of the year for DATE, in the range `1' to `366'.

          mysql> SELECT DAYOFYEAR('1998-02-03');
                  -> 34

   *  `EXTRACT(UNIT FROM DATE)'

     The `EXTRACT()' function uses the same kinds of unit specifiers as
     `DATE_ADD()' or `DATE_SUB()', but extracts parts from the date
     rather than performing date arithmetic.

          mysql> SELECT EXTRACT(YEAR FROM '1999-07-02');
                 -> 1999
          mysql> SELECT EXTRACT(YEAR_MONTH FROM '1999-07-02 01:02:03');
                 -> 199907
          mysql> SELECT EXTRACT(DAY_MINUTE FROM '1999-07-02 01:02:03');
                 -> 20102
          mysql> SELECT EXTRACT(MICROSECOND
              ->                FROM '2003-01-02 10:30:00.000123');
                  -> 123

   *  `FROM_DAYS(N)'

     Given a day number N, returns a `DATE' value.

          mysql> SELECT FROM_DAYS(730669);
                  -> '2007-07-03'

     Use `FROM_DAYS()' with caution on old dates. It is not intended
     for use with values that precede the advent of the Gregorian
     calendar (1582). See *Note mysql-calendar::.

   *  `FROM_UNIXTIME(UNIX_TIMESTAMP)',
     `FROM_UNIXTIME(UNIX_TIMESTAMP,FORMAT)'

     Returns a representation of the UNIX_TIMESTAMP argument as a value
     in `'YYYY-MM-DD HH:MM:SS'' or `YYYYMMDDHHMMSS.uuuuuu' format,
     depending on whether the function is used in a string or numeric
     context.  The value is expressed in the current time zone.
     UNIX_TIMESTAMP is an internal timestamp value such as is produced
     by the `UNIX_TIMESTAMP()' function.

     If FORMAT is given, the result is formatted according to the FORMAT
     string, which is used the same way as listed in the entry for the
     `DATE_FORMAT()' function.

          mysql> SELECT FROM_UNIXTIME(1196440219);
                  -> '2007-11-30 10:30:19'
          mysql> SELECT FROM_UNIXTIME(1196440219) + 0;
                  -> 20071130103019.000000
          mysql> SELECT FROM_UNIXTIME(UNIX_TIMESTAMP(),
              ->                      '%Y %D %M %h:%i:%s %x');
                  -> '2007 30th November 10:30:59 2007'

     Note: If you use `UNIX_TIMESTAMP()' and `FROM_UNIXTIME()' to
     convert between `TIMESTAMP' values and Unix timestamp values, the
     conversion is lossy because the mapping is not one-to-one in both
     directions. For details, see the description of the
     `UNIX_TIMESTAMP()' function.

   *  `GET_FORMAT(DATE|TIME|DATETIME,
     'EUR'|'USA'|'JIS'|'ISO'|'INTERNAL')'

     Returns a format string. This function is useful in combination
     with the `DATE_FORMAT()' and the `STR_TO_DATE()' functions.

     The possible values for the first and second arguments result in
     several possible format strings (for the specifiers used, see the
     table in the `DATE_FORMAT()' function description). ISO format
     refers to ISO 9075, not ISO 8601.

     *Function Call*                          *Result*
     `GET_FORMAT(DATE,'USA')'                 `'%m.%d.%Y''
     `GET_FORMAT(DATE,'JIS')'                 `'%Y-%m-%d''
     `GET_FORMAT(DATE,'ISO')'                 `'%Y-%m-%d''
     `GET_FORMAT(DATE,'EUR')'                 `'%d.%m.%Y''
     `GET_FORMAT(DATE,'INTERNAL')'            `'%Y%m%d''
     `GET_FORMAT(DATETIME,'USA')'             `'%Y-%m-%d %H.%i.%s''
     `GET_FORMAT(DATETIME,'JIS')'             `'%Y-%m-%d %H:%i:%s''
     `GET_FORMAT(DATETIME,'ISO')'             `'%Y-%m-%d %H:%i:%s''
     `GET_FORMAT(DATETIME,'EUR')'             `'%Y-%m-%d %H.%i.%s''
     `GET_FORMAT(DATETIME,'INTERNAL')'        `'%Y%m%d%H%i%s''
     `GET_FORMAT(TIME,'USA')'                 `'%h:%i:%s %p''
     `GET_FORMAT(TIME,'JIS')'                 `'%H:%i:%s''
     `GET_FORMAT(TIME,'ISO')'                 `'%H:%i:%s''
     `GET_FORMAT(TIME,'EUR')'                 `'%H.%i.%s''
     `GET_FORMAT(TIME,'INTERNAL')'            `'%H%i%s''

     `TIMESTAMP' can also be used as the first argument to
     `GET_FORMAT()', in which case the function returns the same values
     as for `DATETIME'.

          mysql> SELECT DATE_FORMAT('2003-10-03',GET_FORMAT(DATE,'EUR'));
                  -> '03.10.2003'
          mysql> SELECT STR_TO_DATE('10.31.2003',GET_FORMAT(DATE,'USA'));
                  -> '2003-10-31'

   *  `HOUR(TIME)'

     Returns the hour for TIME. The range of the return value is `0' to
     `23' for time-of-day values. However, the range of `TIME' values
     actually is much larger, so `HOUR' can return values greater than
     `23'.

          mysql> SELECT HOUR('10:05:03');
                  -> 10
          mysql> SELECT HOUR('272:59:59');
                  -> 272

   *  `LAST_DAY(DATE)'

     Takes a date or datetime value and returns the corresponding value
     for the last day of the month. Returns `NULL' if the argument is
     invalid.

          mysql> SELECT LAST_DAY('2003-02-05');
                  -> '2003-02-28'
          mysql> SELECT LAST_DAY('2004-02-05');
                  -> '2004-02-29'
          mysql> SELECT LAST_DAY('2004-01-01 01:01:01');
                  -> '2004-01-31'
          mysql> SELECT LAST_DAY('2003-03-32');
                  -> NULL

   *  `LOCALTIME', `LOCALTIME()'

     `LOCALTIME' and `LOCALTIME()' are synonyms for `NOW()'.

   *  `LOCALTIMESTAMP', `LOCALTIMESTAMP()'

     `LOCALTIMESTAMP' and `LOCALTIMESTAMP()' are synonyms for `NOW()'.

   *  `MAKEDATE(YEAR,DAYOFYEAR)'

     Returns a date, given year and day-of-year values.  DAYOFYEAR must
     be greater than 0 or the result is `NULL'.

          mysql> SELECT MAKEDATE(2001,31), MAKEDATE(2001,32);
                  -> '2001-01-31', '2001-02-01'
          mysql> SELECT MAKEDATE(2001,365), MAKEDATE(2004,365);
                  -> '2001-12-31', '2004-12-30'
          mysql> SELECT MAKEDATE(2001,0);
                  -> NULL

   *  `MAKETIME(HOUR,MINUTE,SECOND)'

     Returns a time value calculated from the HOUR, MINUTE, and SECOND
     arguments.

          mysql> SELECT MAKETIME(12,15,30);
                  -> '12:15:30'

   *  `MICROSECOND(EXPR)'

     Returns the microseconds from the time or datetime expression EXPR
     as a number in the range from `0' to `999999'.

          mysql> SELECT MICROSECOND('12:00:00.123456');
                  -> 123456
          mysql> SELECT MICROSECOND('2009-12-31 23:59:59.000010');
                  -> 10

   *  `MINUTE(TIME)'

     Returns the minute for TIME, in the range `0' to `59'.

          mysql> SELECT MINUTE('98-02-03 10:05:03');
                  -> 5

   *  `MONTH(DATE)'

     Returns the month for DATE, in the range `1' to `12' for January
     to December, or `0' for dates such as `'0000-00-00'' or
     `'2008-00-00'' that have a zero month part.

          mysql> SELECT MONTH('1998-02-03');
                  -> 2

   *  `MONTHNAME(DATE)'

     Returns the full name of the month for DATE. As of MySQL 5.1.12,
     the language used for the name is controlled by the value of the
     `lc_time_names' system variable (*Note locale-support::).

          mysql> SELECT MONTHNAME('1998-02-05');
                  -> 'February'

   *  `NOW()'

     Returns the current date and time as a value in `'YYYY-MM-DD
     HH:MM:SS'' or `YYYYMMDDHHMMSS.uuuuuu' format, depending on whether
     the function is used in a string or numeric context.  The value is
     expressed in the current time zone.

          mysql> SELECT NOW();
                  -> '2007-12-15 23:50:26'
          mysql> SELECT NOW() + 0;
                  -> 20071215235026.000000

     `NOW()' returns a constant time that indicates the time at which
     the statement began to execute. (Within a stored routine or
     trigger, `NOW()' returns the time at which the routine or
     triggering statement began to execute.)  This differs from the
     behavior for `SYSDATE()', which returns the exact time at which it
     executes.

          mysql> SELECT NOW(), SLEEP(2), NOW();
          +---------------------+----------+---------------------+
          | NOW()               | SLEEP(2) | NOW()               |
          +---------------------+----------+---------------------+
          | 2006-04-12 13:47:36 |        0 | 2006-04-12 13:47:36 |
          +---------------------+----------+---------------------+

          mysql> SELECT SYSDATE(), SLEEP(2), SYSDATE();
          +---------------------+----------+---------------------+
          | SYSDATE()           | SLEEP(2) | SYSDATE()           |
          +---------------------+----------+---------------------+
          | 2006-04-12 13:47:44 |        0 | 2006-04-12 13:47:46 |
          +---------------------+----------+---------------------+

     In addition, the `SET TIMESTAMP' statement affects the value
     returned by `NOW()' but not by `SYSDATE()'. This means that
     timestamp settings in the binary log have no effect on invocations
     of `SYSDATE()'.

     See the description for `SYSDATE()' for additional information
     about the differences between the two functions.

   *  `PERIOD_ADD(P,N)'

     Adds N months to period P (in the format `YYMM' or `YYYYMM').
     Returns a value in the format `YYYYMM'. Note that the period
     argument P is _not_ a date value.

          mysql> SELECT PERIOD_ADD(9801,2);
                  -> 199803

   *  `PERIOD_DIFF(P1,P2)'

     Returns the number of months between periods P1 and P2. P1 and P2
     should be in the format `YYMM' or `YYYYMM'. Note that the period
     arguments P1 and P2 are _not_ date values.

          mysql> SELECT PERIOD_DIFF(9802,199703);
                  -> 11

   *  `QUARTER(DATE)'

     Returns the quarter of the year for DATE, in the range `1' to `4'.

          mysql> SELECT QUARTER('98-04-01');
                  -> 2

   *  `SECOND(TIME)'

     Returns the second for TIME, in the range `0' to `59'.

          mysql> SELECT SECOND('10:05:03');
                  -> 3

   *  `SEC_TO_TIME(SECONDS)'

     Returns the SECONDS argument, converted to hours, minutes, and
     seconds, as a `TIME' value. The range of the result is constrained
     to that of the `TIME' data type.  A warning occurs if the argument
     corresponds to a value outside that range.

          mysql> SELECT SEC_TO_TIME(2378);
                  -> '00:39:38'
          mysql> SELECT SEC_TO_TIME(2378) + 0;
                  -> 3938

   *  `STR_TO_DATE(STR,FORMAT)'

     This is the inverse of the `DATE_FORMAT()' function. It takes a
     string STR and a format string FORMAT.  `STR_TO_DATE()' returns a
     `DATETIME' value if the format string contains both date and time
     parts, or a `DATE' or `TIME' value if the string contains only
     date or time parts.

     The date, time, or datetime values contained in STR should be
     given in the format indicated by FORMAT. For the specifiers that
     can be used in FORMAT, see the `DATE_FORMAT()' function
     description. If STR contains an illegal date, time, or datetime
     value, `STR_TO_DATE()' returns `NULL'. An illegal value also
     produces a warning.

     Range checking on the parts of date values is as described in
     *Note datetime::. This means, for example, that `zero' dates or
     dates with part values of 0 are allowed unless the SQL mode is set
     to disallow such values.

          mysql> SELECT STR_TO_DATE('00/00/0000', '%m/%d/%Y');
                  -> '0000-00-00'
          mysql> SELECT STR_TO_DATE('04/31/2004', '%m/%d/%Y');
                  -> '2004-04-31'

     *Note*:

     You cannot use format `"%X%V"' to convert a year-week string to a
     date because the combination of a year and week does not uniquely
     identify a year and month if the week crosses a month boundary. To
     convert a year-week to a date, then you should also specify the
     weekday:

          mysql> SELECT STR_TO_DATE('200442 Monday', '%X%V %W');
                  -> '2004-10-18'

   *  `SUBDATE(DATE,INTERVAL EXPR UNIT)', `SUBDATE(EXPR,DAYS)'

     When invoked with the `INTERVAL' form of the second argument,
     `SUBDATE()' is a synonym for `DATE_SUB()'. For information on the
     `INTERVAL' UNIT argument, see the discussion for `DATE_ADD()'.

          mysql> SELECT DATE_SUB('2008-01-02', INTERVAL 31 DAY);
                  -> '2007-12-02'
          mysql> SELECT SUBDATE('2008-01-02', INTERVAL 31 DAY);
                  -> '2007-12-02'

     The second form allows the use of an integer value for DAYS. In
     such cases, it is interpreted as the number of days to be
     subtracted from the date or datetime expression EXPR.

          mysql> SELECT SUBDATE('2008-01-02 12:00:00', 31);
                  -> '2007-12-02 12:00:00'

   *  `SUBTIME(EXPR1,EXPR2)'

     `SUBTIME()' returns EXPR1 - EXPR2 expressed as a value in the same
     format as EXPR1.  EXPR1 is a time or datetime expression, and
     EXPR2 is a time expression.

          mysql> SELECT SUBTIME('2007-12-31 23:59:59.999999','1 1:1:1.000002');
                  -> '2007-12-30 22:58:58.999997'
          mysql> SELECT SUBTIME('01:00:00.999999', '02:00:00.999998');
                  -> '-00:59:59.999999'

   *  `SYSDATE()'

     Returns the current date and time as a value in `'YYYY-MM-DD
     HH:MM:SS'' or `YYYYMMDDHHMMSS.uuuuuu' format, depending on whether
     the function is used in a string or numeric context.

     `SYSDATE()' returns the time at which it executes. This differs
     from the behavior for `NOW()', which returns a constant time that
     indicates the time at which the statement began to execute.
     (Within a stored routine or trigger, `NOW()' returns the time at
     which the routine or triggering statement began to execute.)

          mysql> SELECT NOW(), SLEEP(2), NOW();
          +---------------------+----------+---------------------+
          | NOW()               | SLEEP(2) | NOW()               |
          +---------------------+----------+---------------------+
          | 2006-04-12 13:47:36 |        0 | 2006-04-12 13:47:36 |
          +---------------------+----------+---------------------+

          mysql> SELECT SYSDATE(), SLEEP(2), SYSDATE();
          +---------------------+----------+---------------------+
          | SYSDATE()           | SLEEP(2) | SYSDATE()           |
          +---------------------+----------+---------------------+
          | 2006-04-12 13:47:44 |        0 | 2006-04-12 13:47:46 |
          +---------------------+----------+---------------------+

     In addition, the `SET TIMESTAMP' statement affects the value
     returned by `NOW()' but not by `SYSDATE()'. This means that
     timestamp settings in the binary log have no effect on invocations
     of `SYSDATE()'.

     Because `SYSDATE()' can return different values even within the
     same statement, and is not affected by `SET TIMESTAMP', it is
     non-deterministic and therefore unsafe for replication if
     statement-based binary logging is used. If that is a problem, you
     can use row-based logging, or start the server with the
     `--sysdate-is-now' option to cause `SYSDATE()' to be an alias for
     `NOW()'. The non-deterministic nature of `SYSDATE()' also means
     that indexes cannot be used for evaluating expressions that refer
     to it.

   *  `TIME(EXPR)'

     Extracts the time part of the time or datetime expression EXPR and
     returns it as a string.

          mysql> SELECT TIME('2003-12-31 01:02:03');
                  -> '01:02:03'
          mysql> SELECT TIME('2003-12-31 01:02:03.000123');
                  -> '01:02:03.000123'

   *  `TIMEDIFF(EXPR1,EXPR2)'

     `TIMEDIFF()' returns EXPR1 - EXPR2 expressed as a time value.
     EXPR1 and EXPR2 are time or date-and-time expressions, but both
     must be of the same type.

          mysql> SELECT TIMEDIFF('2000:01:01 00:00:00',
              ->                 '2000:01:01 00:00:00.000001');
                  -> '-00:00:00.000001'
          mysql> SELECT TIMEDIFF('2008-12-31 23:59:59.000001',
              ->                 '2008-12-30 01:01:01.000002');
                  -> '46:58:57.999999'

   *  `TIMESTAMP(EXPR)', `TIMESTAMP(EXPR1,EXPR2)'

     With a single argument, this function returns the date or datetime
     expression EXPR as a datetime value. With two arguments, it adds
     the time expression EXPR2 to the date or datetime expression EXPR1
     and returns the result as a datetime value.

          mysql> SELECT TIMESTAMP('2003-12-31');
                  -> '2003-12-31 00:00:00'
          mysql> SELECT TIMESTAMP('2003-12-31 12:00:00','12:00:00');
                  -> '2004-01-01 00:00:00'

   *  `TIMESTAMPADD(UNIT,INTERVAL,DATETIME_EXPR)'

     Adds the integer expression INTERVAL to the date or datetime
     expression DATETIME_EXPR. The unit for INTERVAL is given by the
     UNIT argument, which should be one of the following values:
     `FRAC_SECOND' (microseconds), `SECOND', `MINUTE', `HOUR', `DAY',
     `WEEK', `MONTH', `QUARTER', or `YEAR'.

     Beginning with MySQL MySQL 5.1.24, it is possible to use
     `MICROSECOND' in place of `FRAC_SECOND' with this function, and
     `FRAC_SECOND' is deprecated.

     The UNIT value may be specified using one of keywords as shown, or
     with a prefix of `SQL_TSI_'. For example, `DAY' and `SQL_TSI_DAY'
     both are legal.

          mysql> SELECT TIMESTAMPADD(MINUTE,1,'2003-01-02');
                  -> '2003-01-02 00:01:00'
          mysql> SELECT TIMESTAMPADD(WEEK,1,'2003-01-02');
                  -> '2003-01-09'

   *  `TIMESTAMPDIFF(UNIT,DATETIME_EXPR1,DATETIME_EXPR2)'

     Returns the integer difference between the date or datetime
     expressions DATETIME_EXPR1 and DATETIME_EXPR2. The unit for the
     result is given by the UNIT argument. The legal values for UNIT
     are the same as those listed in the description of the
     `TIMESTAMPADD()' function.

          mysql> SELECT TIMESTAMPDIFF(MONTH,'2003-02-01','2003-05-01');
                  -> 3
          mysql> SELECT TIMESTAMPDIFF(YEAR,'2002-05-01','2001-01-01');
                  -> -1

   *  `TIME_FORMAT(TIME,FORMAT)'

     This is used like the `DATE_FORMAT()' function, but the FORMAT
     string may contain format specifiers only for hours, minutes, and
     seconds. Other specifiers produce a `NULL' value or `0'.

     If the TIME value contains an hour part that is greater than `23',
     the `%H' and `%k' hour format specifiers produce a value larger
     than the usual range of `0..23'. The other hour format specifiers
     produce the hour value modulo 12.

          mysql> SELECT TIME_FORMAT('100:00:00', '%H %k %h %I %l');
                  -> '100 100 04 04 4'

   *  `TIME_TO_SEC(TIME)'

     Returns the TIME argument, converted to seconds.

          mysql> SELECT TIME_TO_SEC('22:23:00');
                  -> 80580
          mysql> SELECT TIME_TO_SEC('00:39:38');
                  -> 2378

   *  `TO_DAYS(DATE)'

     Given a date DATE, returns a day number (the number of days since
     year 0).

          mysql> SELECT TO_DAYS(950501);
                  -> 728779
          mysql> SELECT TO_DAYS('2007-10-07');
                  -> 733321

     `TO_DAYS()' is not intended for use with values that precede the
     advent of the Gregorian calendar (1582), because it does not take
     into account the days that were lost when the calendar was
     changed. For dates before 1582 (and possibly a later year in other
     locales), results from this function are not reliable. See *Note
     mysql-calendar::, for details.

     Remember that MySQL converts two-digit year values in dates to
     four-digit form using the rules in *Note date-and-time-types::.
     For example, `'1997-10-07'' and `'97-10-07'' are seen as identical
     dates:

          mysql> SELECT TO_DAYS('1997-10-07'), TO_DAYS('97-10-07');
                  -> 729669, 729669

   *  `UNIX_TIMESTAMP()', `UNIX_TIMESTAMP(DATE)'

     If called with no argument, returns a Unix timestamp (seconds
     since `'1970-01-01 00:00:00'' UTC) as an unsigned integer. If
     `UNIX_TIMESTAMP()' is called with a DATE argument, it returns the
     value of the argument as seconds since `'1970-01-01 00:00:00'' UTC.
     DATE may be a `DATE' string, a `DATETIME' string, a `TIMESTAMP',
     or a number in the format `YYMMDD' or `YYYYMMDD'. The server
     interprets DATE as a value in the current time zone and converts
     it to an internal value in UTC. Clients can set their time zone as
     described in *Note time-zone-support::.

          mysql> SELECT UNIX_TIMESTAMP();
                  -> 1196440210
          mysql> SELECT UNIX_TIMESTAMP('2007-11-30 10:30:19');
                  -> 1196440219

     When `UNIX_TIMESTAMP()' is used on a `TIMESTAMP' column, the
     function returns the internal timestamp value directly, with no
     implicit `string-to-Unix-timestamp' conversion. If you pass an
     out-of-range date to `UNIX_TIMESTAMP()', it returns `0'.

     Note: If you use `UNIX_TIMESTAMP()' and `FROM_UNIXTIME()' to
     convert between `TIMESTAMP' values and Unix timestamp values, the
     conversion is lossy because the mapping is not one-to-one in both
     directions. For example, due to conventions for local time zone
     changes, it is possible for two `UNIX_TIMESTAMP()' to map two
     `TIMESTAMP' values to the same Unix timestamp value.
     `FROM_UNIXTIME()' will map that value back to only one of the
     original `TIMESTAMP' values. Here is an example, using `TIMESTAMP'
     values in the `CET' time zone:

          mysql> SELECT UNIX_TIMESTAMP('2005-03-27 03:00:00');
          +---------------------------------------+
          | UNIX_TIMESTAMP('2005-03-27 03:00:00') |
          +---------------------------------------+
          |                            1111885200 |
          +---------------------------------------+
          mysql> SELECT UNIX_TIMESTAMP('2005-03-27 02:00:00');
          +---------------------------------------+
          | UNIX_TIMESTAMP('2005-03-27 02:00:00') |
          +---------------------------------------+
          |                            1111885200 |
          +---------------------------------------+
          mysql> SELECT FROM_UNIXTIME(1111885200);
          +---------------------------+
          | FROM_UNIXTIME(1111885200) |
          +---------------------------+
          | 2005-03-27 03:00:00       |
          +---------------------------+

     If you want to subtract `UNIX_TIMESTAMP()' columns, you might want
     to cast the result to signed integers. See *Note cast-functions::.

   *  `UTC_DATE', `UTC_DATE()'

     Returns the current UTC date as a value in `'YYYY-MM-DD'' or
     `YYYYMMDD' format, depending on whether the function is used in a
     string or numeric context.

          mysql> SELECT UTC_DATE(), UTC_DATE() + 0;
                  -> '2003-08-14', 20030814

   *  `UTC_TIME', `UTC_TIME()'

     Returns the current UTC time as a value in `'HH:MM:SS'' or
     `HHMMSS.uuuuuu' format, depending on whether the function is used
     in a string or numeric context.

          mysql> SELECT UTC_TIME(), UTC_TIME() + 0;
                  -> '18:07:53', 180753.000000

   *  `UTC_TIMESTAMP', `UTC_TIMESTAMP()'

     Returns the current UTC date and time as a value in `'YYYY-MM-DD
     HH:MM:SS'' or `YYYYMMDDHHMMSS.uuuuuu' format, depending on whether
     the function is used in a string or numeric context.

          mysql> SELECT UTC_TIMESTAMP(), UTC_TIMESTAMP() + 0;
                  -> '2003-08-14 18:08:04', 20030814180804.000000

   *  `WEEK(DATE[,MODE])'

     This function returns the week number for DATE. The two-argument
     form of `WEEK()' allows you to specify whether the week starts on
     Sunday or Monday and whether the return value should be in the
     range from `0' to `53' or from `1' to `53'. If the MODE argument
     is omitted, the value of the `default_week_format' system variable
     is used. See *Note server-system-variables::.

     The following table describes how the MODE argument works.

             *First day*                 
     *Mode*  *of week*     *Range*       *Week 1 is the first week ...*
     0       Sunday        0-53          with a Sunday in this year
     1       Monday        0-53          with more than 3 days this year
     2       Sunday        1-53          with a Sunday in this year
     3       Monday        1-53          with more than 3 days this year
     4       Sunday        0-53          with more than 3 days this year
     5       Monday        0-53          with a Monday in this year
     6       Sunday        1-53          with more than 3 days this year
     7       Monday        1-53          with a Monday in this year

          mysql> SELECT WEEK('1998-02-20');
                  -> 7
          mysql> SELECT WEEK('1998-02-20',0);
                  -> 7
          mysql> SELECT WEEK('1998-02-20',1);
                  -> 8
          mysql> SELECT WEEK('1998-12-31',1);
                  -> 53

     Note that if a date falls in the last week of the previous year,
     MySQL returns `0' if you do not use `2', `3', `6', or `7' as the
     optional MODE argument:

          mysql> SELECT YEAR('2000-01-01'), WEEK('2000-01-01',0);
                  -> 2000, 0

     One might argue that MySQL should return `52' for the `WEEK()'
     function, because the given date actually occurs in the 52nd week
     of 1999. We decided to return `0' instead because we want the
     function to return `the week number in the given year.' This makes
     use of the `WEEK()' function reliable when combined with other
     functions that extract a date part from a date.

     If you would prefer the result to be evaluated with respect to the
     year that contains the first day of the week for the given date,
     use `0', `2', `5', or `7' as the optional MODE argument.

          mysql> SELECT WEEK('2000-01-01',2);
                  -> 52

     Alternatively, use the `YEARWEEK()' function:

          mysql> SELECT YEARWEEK('2000-01-01');
                  -> 199952
          mysql> SELECT MID(YEARWEEK('2000-01-01'),5,2);
                  -> '52'

   *  `WEEKDAY(DATE)'

     Returns the weekday index for DATE (`0' = Monday, `1' = Tuesday,
     ... `6' = Sunday).

          mysql> SELECT WEEKDAY('2008-02-03 22:23:00');
                  -> 6
          mysql> SELECT WEEKDAY('2007-11-06');
                  -> 1

   *  `WEEKOFYEAR(DATE)'

     Returns the calendar week of the date as a number in the range
     from `1' to `53'.  `WEEKOFYEAR()' is a compatibility function that
     is equivalent to `WEEK(DATE,3)'.

          mysql> SELECT WEEKOFYEAR('1998-02-20');
                  -> 8

   *  `YEAR(DATE)'

     Returns the year for DATE, in the range `1000' to `9999', or `0'
     for the `zero' date.

                  -> 2008

   *  `YEARWEEK(DATE)', `YEARWEEK(DATE,MODE)'

     Returns year and week for a date. The MODE argument works exactly
     like the MODE argument to `WEEK()'. The year in the result may be
     different from the year in the date argument for the first and the
     last week of the year.

          mysql> SELECT YEARWEEK('1987-01-01');
                  -> 198653

     Note that the week number is different from what the `WEEK()'
     function would return (`0') for optional arguments `0' or `1', as
     `WEEK()' then returns the week in the context of the given year.


File: manual.info,  Node: mysql-calendar,  Next: fulltext-search,  Prev: date-and-time-functions,  Up: functions

11.7 What Calendar Is Used By MySQL?
====================================

MySQL uses what is known as a _proleptic Gregorian calendar_.

Every country that has switched from the Julian to the Gregorian
calendar has had to discard at least ten days during the switch.  To
see how this works, consider the month of October 1582, when the first
Julian-to-Gregorian switch occurred:

Monday     Tuesday    Wednesday  Thursday   Friday     Saturday   Sunday
1          2          3          4          15         16         17
18         19         20         21         22         23         24
25         26         27         28         29         30         31

There are no dates between October 4 and October 15. This discontinuity
is called the _cutover_. Any dates before the cutover are Julian, and
any dates following the cutover are Gregorian. Dates during a cutover
are non-existent.

A calendar applied to dates when it wasn't actually in use is called
_proleptic_. Thus, if we assume there was never a cutover and Gregorian
rules always rule, we have a proleptic Gregorian calendar. This is what
is used by MySQL, as is required by standard SQL. For this reason,
dates prior to the cutover stored as MySQL `DATE' or `DATETIME' values
must be adjusted to compensate for the difference. It is important to
realize that the cutover did not occur at the same time in all
countries, and that the later it happened, the more days were lost. For
example, in Great Britain, it took place in 1752, when Wednesday
September 2 was followed by Thursday September 14. Russia remained on
the Julian calendar until 1918, losing 13 days in the process, and what
is popularly referred to as its `October Revolution' occurred in
November according to the Gregorian calendar.


File: manual.info,  Node: fulltext-search,  Next: cast-functions,  Prev: mysql-calendar,  Up: functions

11.8 Full-Text Search Functions
===============================

* Menu:

* fulltext-natural-language::    Natural Language Full-Text Searches
* fulltext-boolean::             Boolean Full-Text Searches
* fulltext-query-expansion::     Full-Text Searches with Query Expansion
* fulltext-stopwords::           Full-Text Stopwords
* fulltext-restrictions::        Full-Text Restrictions
* fulltext-fine-tuning::         Fine-Tuning MySQL Full-Text Search

`MATCH (COL1,COL2,...)  AGAINST (EXPR [SEARCH_MODIFIER])'

     SEARCH_MODIFIER:
       {
            IN BOOLEAN MODE
          | IN NATURAL LANGUAGE MODE
          | IN NATURAL LANGUAGE MODE WITH QUERY EXPANSION
          | WITH QUERY EXPANSION
       }

MySQL has support for full-text indexing and searching:

   * A full-text index in MySQL is an index of type `FULLTEXT'.

   * Full-text indexes can be used only with `MyISAM' tables, and can
     be created only for `CHAR', `VARCHAR', or `TEXT' columns.

   * A `FULLTEXT' index definition can be given in the `CREATE TABLE'
     statement when a table is created, or added later using `ALTER
     TABLE' or `CREATE INDEX'.

   * For large data sets, it is much faster to load your data into a
     table that has no `FULLTEXT' index and then create the index after
     that, than to load data into a table that has an existing
     `FULLTEXT' index.

Full-text searching is performed using `MATCH() ... AGAINST' syntax.
`MATCH()' takes a comma-separated list that names the columns to be
searched.  `AGAINST' takes a string to search for, and an optional
modifier that indicates what type of search to perform.  The search
string must be a literal string, not a variable or a column name. There
are three types of full-text searches:

   * A boolean search interprets the search string using the rules of a
     special query language. The string contains the words to search
     for. It can also contain operators that specify requirements such
     that a word must be present or absent in matching rows, or that it
     should be weighted higher or lower than usual. Common words such
     as `some' or `then' are stopwords and do not match if present in
     the search string. The `IN BOOLEAN MODE' modifier specifies a
     boolean search. For more information, see *Note fulltext-boolean::.

   * A natural language search interprets the search string as a phrase
     in natural human language (a phrase in free text).  There are no
     special operators. The stopword list applies. In addition, words
     that are present in 50% or more of the rows are considered common
     and do not match. Full-text searches are natural language searches
     if the `IN NATURAL LANGUAGE MODE' modifier is given or if no
     modifier is given.

   * A query expansion search is a modification of a natural language
     search. The search string is used to perform a natural language
     search. Then words from the most relevant rows returned by the
     search are added to the search string and the search is done
     again. The query returns the rows from the second search. The `IN
     NATURAL LANGUAGE MODE WITH QUERY EXPANSION' or `WITH QUERY
     EXPANSION' modifier specifies a query expansion search. For more
     information, see *Note fulltext-query-expansion::.

The `IN NATURAL LANGUAGE MODE' and `IN NATURAL LANGUAGE MODE WITH QUERY
EXPANSION' modifiers were added in MySQL 5.1.7.

Constraints on full-text searching are listed in *Note
fulltext-restrictions::.


File: manual.info,  Node: fulltext-natural-language,  Next: fulltext-boolean,  Prev: fulltext-search,  Up: fulltext-search

11.8.1 Natural Language Full-Text Searches
------------------------------------------

By default or with the `IN NATURAL LANGUAGE MODE' modifier, the
`MATCH()' function performs a natural language search for a string
against a _text collection_. A collection is a set of one or more
columns included in a `FULLTEXT' index. The search string is given as
the argument to `AGAINST()'. For each row in the table, `MATCH()'
returns a relevance value; that is, a similarity measure between the
search string and the text in that row in the columns named in the
`MATCH()' list.

     mysql> CREATE TABLE articles (
         ->   id INT UNSIGNED AUTO_INCREMENT NOT NULL PRIMARY KEY,
         ->   title VARCHAR(200),
         ->   body TEXT,
         ->   FULLTEXT (title,body)
         -> );
     Query OK, 0 rows affected (0.00 sec)

     mysql> INSERT INTO articles (title,body) VALUES
         -> ('MySQL Tutorial','DBMS stands for DataBase ...'),
         -> ('How To Use MySQL Well','After you went through a ...'),
         -> ('Optimizing MySQL','In this tutorial we will show ...'),
         -> ('1001 MySQL Tricks','1. Never run ysqld as root. 2. ...'),
         -> ('MySQL vs. YourSQL','In the following database comparison ...'),
         -> ('MySQL Security','When configured properly, MySQL ...');
     Query OK, 6 rows affected (0.00 sec)
     Records: 6  Duplicates: 0  Warnings: 0

     mysql> SELECT * FROM articles
         -> WHERE MATCH (title,body)
         -> AGAINST ('database' IN NATURAL LANGUAGE MODE);
     +----+-------------------+------------------------------------------+
     | id | title             | body                                     |
     +----+-------------------+------------------------------------------+
     |  5 | MySQL vs. YourSQL | In the following database comparison ... |
     |  1 | MySQL Tutorial    | DBMS stands for DataBase ...             |
     +----+-------------------+------------------------------------------+
     2 rows in set (0.00 sec)

By default, the search is performed in case-insensitive fashion.
However, you can perform a case-sensitive full-text search by using a
binary collation for the indexed columns. For example, a column that
uses the `latin1' character set of can be assigned a collation of
`latin1_bin' to make it case sensitive for full-text searches.

When `MATCH()' is used in a `WHERE' clause, as in the example shown
earlier, the rows returned are automatically sorted with the highest
relevance first. Relevance values are non-negative floating-point
numbers. Zero relevance means no similarity.  Relevance is computed
based on the number of words in the row, the number of unique words in
that row, the total number of words in the collection, and the number
of documents (rows) that contain a particular word.

To simply count matches, you could use a query like this:

     mysql> SELECT COUNT(*) FROM articles
         -> WHERE MATCH (title,body)
         -> AGAINST ('database' IN NATURAL LANGUAGE MODE);
     +----------+
     | COUNT(*) |
     +----------+
     |        2 |
     +----------+
     1 row in set (0.00 sec)

However, you might find it quicker to rewrite the query as follows:

     mysql> SELECT
         -> COUNT(IF(MATCH (title,body) AGAINST ('database' IN NATURAL LANGUAGE MODE), 1, NULL))
         -> AS count
         -> FROM articles;
     +-------+
     | count |
     +-------+
     |     2 |
     +-------+
     1 row in set (0.03 sec)

The first query sorts the results by relevance whereas the second does
not. However, the second query performs a full table scan and the first
does not. The first may be faster if the search matches few rows;
otherwise, the second may be faster because it would read many rows
anyway.

For natural-language full-text searches, it is a requirement that the
columns named in the `MATCH()' function be the same columns included in
some `FULLTEXT' index in your table. For the preceding query, note that
the columns named in the `MATCH()' function (`title' and `body') are the
same as those named in the definition of the `article' table's
`FULLTEXT' index. If you wanted to search the `title' or `body'
separately, you would need to create separate `FULLTEXT' indexes for
each column.

It is also possible to perform a boolean search or a search with query
expansion. These search types are described in *Note
fulltext-boolean::, and *Note fulltext-query-expansion::.

A full-text search that uses an index can name columns only from a
single table in the `MATCH()' clause because an index cannot span
multiple tables. A boolean search can be done in the absence of an
index (albeit more slowly), in which case it is possible to name
columns from multiple tables.

The preceding example is a basic illustration that shows how to use the
`MATCH()' function where rows are returned in order of decreasing
relevance. The next example shows how to retrieve the relevance values
explicitly.  Returned rows are not ordered because the `SELECT'
statement includes neither `WHERE' nor `ORDER BY' clauses:

     mysql> SELECT id, MATCH (title,body)
         -> AGAINST ('Tutorial' IN NATURAL LANGUAGE MODE) AS score
         -> FROM articles;
     +----+------------------+
     | id | score            |
     +----+------------------+
     |  1 | 0.65545833110809 |
     |  2 |                0 |
     |  3 | 0.66266459226608 |
     |  4 |                0 |
     |  5 |                0 |
     |  6 |                0 |
     +----+------------------+
     6 rows in set (0.00 sec)

The following example is more complex. The query returns the relevance
values and it also sorts the rows in order of decreasing relevance. To
achieve this result, you should specify `MATCH()' twice: once in the
`SELECT' list and once in the `WHERE' clause. This causes no additional
overhead, because the MySQL optimizer notices that the two `MATCH()'
calls are identical and invokes the full-text search code only once.

     mysql> SELECT id, body, MATCH (title,body) AGAINST
         -> ('Security implications of running MySQL as root'
         -> IN NATURAL LANGUAGE MODE) AS score
         -> FROM articles WHERE MATCH (title,body) AGAINST
         -> ('Security implications of running MySQL as root'
         -> IN NATURAL LANGUAGE MODE);
     +----+-------------------------------------+-----------------+
     | id | body                                | score           |
     +----+-------------------------------------+-----------------+
     |  4 | 1. Never run mysqld as root. 2. ... | 1.5219271183014 |
     |  6 | When configured properly, MySQL ... | 1.3114095926285 |
     +----+-------------------------------------+-----------------+
     2 rows in set (0.00 sec)

The MySQL `FULLTEXT' implementation regards any sequence of true word
characters (letters, digits, and underscores) as a word. That sequence
may also contain apostrophes (``'''), but not more than one in a row.
This means that `aaa'bbb' is regarded as one word, but `aaa''bbb' is
regarded as two words. Apostrophes at the beginning or the end of a
word are stripped by the `FULLTEXT' parser; `'aaa'bbb'' would be parsed
as `aaa'bbb'.

The `FULLTEXT' parser determines where words start and end by looking
for certain delimiter characters; for example, `` '' (space), ``,''
(comma), and ``.'' (period). If words are not separated by delimiters
(as in, for example, Chinese), the `FULLTEXT' parser cannot determine
where a word begins or ends. To be able to add words or other indexed
terms in such languages to a `FULLTEXT' index, you must preprocess them
so that they are separated by some arbitrary delimiter such as ``"''.

In MySQL 5.1, it is possible to write a plugin that replaces the
built-in full-text parser. For details, see *Note plugin-api::. For
example parser plugin source code, see the `plugin/fulltext' directory
of a MySQL source distribution.

Some words are ignored in full-text searches:

   * Any word that is too short is ignored. The default minimum length
     of words that are found by full-text searches is four characters.

   * Words in the stopword list are ignored. A stopword is a word such
     as `the' or `some' that is so common that it is considered to have
     zero semantic value.  There is a built-in stopword list, but it
     can be overwritten by a user-defined list.

The default stopword list is given in *Note fulltext-stopwords::. The
default minimum word length and stopword list can be changed as
described in *Note fulltext-fine-tuning::.

Every correct word in the collection and in the query is weighted
according to its significance in the collection or query. Consequently,
a word that is present in many documents has a lower weight (and may
even have a zero weight), because it has lower semantic value in this
particular collection.  Conversely, if the word is rare, it receives a
higher weight.  The weights of the words are combined to compute the
relevance of the row.

Such a technique works best with large collections (in fact, it was
carefully tuned this way). For very small tables, word distribution
does not adequately reflect their semantic value, and this model may
sometimes produce bizarre results. For example, although the word
`MySQL' is present in every row of the `articles' table shown earlier,
a search for the word produces no results:

     mysql> SELECT * FROM articles
         -> WHERE MATCH (title,body)
         -> AGAINST ('MySQL' IN NATURAL LANGUAGE MODE);
     Empty set (0.00 sec)

The search result is empty because the word `MySQL' is present in at
least 50% of the rows. As such, it is effectively treated as a
stopword. For large data sets, this is the most desirable behavior: A
natural language query should not return every second row from a 1GB
table. For small data sets, it may be less desirable.

A word that matches half of the rows in a table is less likely to
locate relevant documents. In fact, it most likely finds plenty of
irrelevant documents. We all know this happens far too often when we
are trying to find something on the Internet with a search engine. It
is with this reasoning that rows containing the word are assigned a low
semantic value for _the particular data set in which they occur_. A
given word may reach the 50% threshold in one data set but not another.

The 50% threshold has a significant implication when you first try
full-text searching to see how it works: If you create a table and
insert only one or two rows of text into it, every word in the text
occurs in at least 50% of the rows. As a result, no search returns any
results. Be sure to insert at least three rows, and preferably many
more. Users who need to bypass the 50% limitation can use the boolean
search mode; see *Note fulltext-boolean::.


File: manual.info,  Node: fulltext-boolean,  Next: fulltext-query-expansion,  Prev: fulltext-natural-language,  Up: fulltext-search

11.8.2 Boolean Full-Text Searches
---------------------------------

MySQL can perform boolean full-text searches using the `IN BOOLEAN
MODE' modifier:

     mysql> SELECT * FROM articles WHERE MATCH (title,body)
         -> AGAINST ('+MySQL -YourSQL' IN BOOLEAN MODE);
     +----+-----------------------+-------------------------------------+
     | id | title                 | body                                |
     +----+-----------------------+-------------------------------------+
     |  1 | MySQL Tutorial        | DBMS stands for DataBase ...        |
     |  2 | How To Use MySQL Well | After you went through a ...        |
     |  3 | Optimizing MySQL      | In this tutorial we will show ...   |
     |  4 | 1001 MySQL Tricks     | 1. Never run mysqld as root. 2. ... |
     |  6 | MySQL Security        | When configured properly, MySQL ... |
     +----+-----------------------+-------------------------------------+

The `+' and `-' operators indicate that a word is required to be
present or absent, respectively, for a match to occur. Thus, this query
retrieves all the rows that contain the word `MySQL' but that do _not_
contain the word `YourSQL'.

*Note*:

In implementing this feature, MySQL uses what is sometimes referred to
as _implied Boolean logic_, in which

   * `+' stands for `AND'

   * `-' stands for `NOT'

   * [_no operator_] implies `OR'

Boolean full-text searches have these characteristics:

   * They do not use the 50% threshold.

   * They do not automatically sort rows in order of decreasing
     relevance. You can see this from the preceding query result: The
     row with the highest relevance is the one that contains `MySQL'
     twice, but it is listed last, not first.

   * They can work even without a `FULLTEXT' index, although a search
     executed in this fashion would be quite slow.

   * The minimum and maximum word length full-text parameters apply.

   * The stopword list applies.

The boolean full-text search capability supports the following
operators:

   * `+'

     A leading plus sign indicates that this word _must_ be present in
     each row that is returned.

   * `-'

     A leading minus sign indicates that this word must _not_ be
     present in any of the rows that are returned.

     Note: The `-' operator acts only to exclude rows that are
     otherwise matched by other search terms. Thus, a boolean-mode
     search that contains only terms preceded by `-' returns an empty
     result. It does not return `all rows except those containing any
     of the excluded terms.'

   * (no operator)

     By default (when neither `+' nor `-' is specified) the word is
     optional, but the rows that contain it are rated higher. This
     mimics the behavior of `MATCH() ...  AGAINST()' without the `IN
     BOOLEAN MODE' modifier.

   * `> <'

     These two operators are used to change a word's contribution to
     the relevance value that is assigned to a row. The `>' operator
     increases the contribution and the `<' operator decreases it. See
     the example following this list.

   * `( )'

     Parentheses group words into subexpressions. Parenthesized groups
     can be nested.

   * `~'

     A leading tilde acts as a negation operator, causing the word's
     contribution to the row's relevance to be negative.  This is
     useful for marking `noise' words. A row containing such a word is
     rated lower than others, but is not excluded altogether, as it
     would be with the `-' operator.

   * `*'

     The asterisk serves as the truncation (or wildcard) operator.
     Unlike the other operators, it should be _appended_ to the word to
     be affected.  Words match if they begin with the word preceding the
     `*' operator.

     If a stopword or too-short word is specified with the truncation
     operator, it will not be stripped from a boolean query. For
     example, a search for `'+word +stopword*'' will likely return
     fewer rows than a search for `'+word +stopword'' because the
     former query remains as is and requires `stopword*' to be present
     in a document.  The latter query is transformed to `+word'.

   * `"'

     A phrase that is enclosed within double quote (``"'') characters
     matches only rows that contain the phrase _literally, as it was
     typed_. The full-text engine splits the phrase into words,
     performs a search in the `FULLTEXT' index for the words. Non-word
     characters need not be matched exactly: Phrase searching requires
     only that matches contain exactly the same words as the phrase and
     in the same order. For example, `"test phrase"' matches `"test,
     phrase"'.

     If the phrase contains no words that are in the index, the result
     is empty. For example, if all words are either stopwords or
     shorter than the minimum length of indexed words, the result is
     empty.

The following examples demonstrate some search strings that use boolean
full-text operators:

   * `'apple banana''

     Find rows that contain at least one of the two words.

   * `'+apple +juice''

     Find rows that contain both words.

   * `'+apple macintosh''

     Find rows that contain the word `apple', but rank rows higher if
     they also contain `macintosh'.

   * `'+apple -macintosh''

     Find rows that contain the word `apple' but not `macintosh'.

   * `'+apple ~macintosh''

     Find rows that contain the word `apple', but if the row also
     contains the word `macintosh', rate it lower than if row does not.
     This is `softer' than a search for `'+apple -macintosh'', for
     which the presence of `macintosh' causes the row not to be returned
     at all.

   * `'+apple +(>turnover <strudel)''

     Find rows that contain the words `apple' and `turnover', or
     `apple' and `strudel' (in any order), but rank `apple turnover'
     higher than `apple strudel'.

   * `'apple*''

     Find rows that contain words such as `apple', `apples',
     `applesauce', or `applet'.

   * `'"some words"''

     Find rows that contain the exact phrase `some words' (for example,
     rows that contain `some words of wisdom' but not `some noise
     words'). Note that the ``"'' characters that enclose the phrase
     are operator characters that delimit the phrase.  They are not the
     quotes that enclose the search string itself.


File: manual.info,  Node: fulltext-query-expansion,  Next: fulltext-stopwords,  Prev: fulltext-boolean,  Up: fulltext-search

11.8.3 Full-Text Searches with Query Expansion
----------------------------------------------

Full-text search supports query expansion (and in particular, its
variant `blind query expansion'). This is generally useful when a
search phrase is too short, which often means that the user is relying
on implied knowledge that the full-text search engine lacks. For
example, a user searching for `database' may really mean that `MySQL',
`Oracle', `DB2', and `RDBMS' all are phrases that should match
`databases' and should be returned, too. This is implied knowledge.

Blind query expansion (also known as automatic relevance feedback) is
enabled by adding `WITH QUERY EXPANSION' or `IN NATURAL LANGUAGE MODE
WITH QUERY EXPANSION' following the search phrase. It works by
performing the search twice, where the search phrase for the second
search is the original search phrase concatenated with the few most
highly relevant documents from the first search.  Thus, if one of these
documents contains the word `databases' and the word `MySQL', the
second search finds the documents that contain the word `MySQL' even if
they do not contain the word `database'. The following example shows
this difference:

     mysql> SELECT * FROM articles
         -> WHERE MATCH (title,body)
         -> AGAINST ('database' IN NATURAL LANGUAGE MODE);
     +----+-------------------+------------------------------------------+
     | id | title             | body                                     |
     +----+-------------------+------------------------------------------+
     |  5 | MySQL vs. YourSQL | In the following database comparison ... |
     |  1 | MySQL Tutorial    | DBMS stands for DataBase ...             |
     +----+-------------------+------------------------------------------+
     2 rows in set (0.00 sec)

     mysql> SELECT * FROM articles
         -> WHERE MATCH (title,body)
         -> AGAINST ('database' WITH QUERY EXPANSION);
     +----+-------------------+------------------------------------------+
     | id | title             | body                                     |
     +----+-------------------+------------------------------------------+
     |  1 | MySQL Tutorial    | DBMS stands for DataBase ...             |
     |  5 | MySQL vs. YourSQL | In the following database comparison ... |
     |  3 | Optimizing MySQL  | In this tutorial we will show ...        |
     +----+-------------------+------------------------------------------+
     3 rows in set (0.00 sec)

Another example could be searching for books by Georges Simenon about
Maigret, when a user is not sure how to spell `Maigret'. A search for
`Megre and the reluctant witnesses' finds only `Maigret and the
Reluctant Witnesses' without query expansion. A search with query
expansion finds all books with the word `Maigret' on the second pass.

*Note*:

Because blind query expansion tends to increase noise significantly by
returning non-relevant documents, it is meaningful to use only when a
search phrase is rather short.


File: manual.info,  Node: fulltext-stopwords,  Next: fulltext-restrictions,  Prev: fulltext-query-expansion,  Up: fulltext-search

11.8.4 Full-Text Stopwords
--------------------------

The following table shows the default list of full-text stopwords.

a's            able           about          above          according
accordingly    across         actually       after          afterwards
again          against        ain't          all            allow
allows         almost         alone          along          already
also           although       always         am             among
amongst        an             and            another        any
anybody        anyhow         anyone         anything       anyway
anyways        anywhere       apart          appear         appreciate
appropriate    are            aren't         around         as
aside          ask            asking         associated     at
available      away           awfully        be             became
because        become         becomes        becoming       been
before         beforehand     behind         being          believe
below          beside         besides        best           better
between        beyond         both           brief          but
by             c'mon          c's            came           can
can't          cannot         cant           cause          causes
certain        certainly      changes        clearly        co
com            come           comes          concerning     consequently
consider       considering    contain        containing     contains
corresponding  could          couldn't       course         currently
definitely     described      despite        did            didn't
different      do             does           doesn't        doing
don't          done           down           downwards      during
each           edu            eg             eight          either
else           elsewhere      enough         entirely       especially
et             etc            even           ever           every
everybody      everyone       everything     everywhere     ex
exactly        example        except         far            few
fifth          first          five           followed       following
follows        for            former         formerly       forth
four           from           further        furthermore    get
gets           getting        given          gives          go
goes           going          gone           got            gotten
greetings      had            hadn't         happens        hardly
has            hasn't         have           haven't        having
he             he's           hello          help           hence
her            here           here's         hereafter      hereby
herein         hereupon       hers           herself        hi
him            himself        his            hither         hopefully
how            howbeit        however        i'd            i'll
i'm            i've           ie             if             ignored
immediate      in             inasmuch       inc            indeed
indicate       indicated      indicates      inner          insofar
instead        into           inward         is             isn't
it             it'd           it'll          it's           its
itself         just           keep           keeps          kept
know           knows          known          last           lately
later          latter         latterly       least          less
lest           let            let's          like           liked
likely         little         look           looking        looks
ltd            mainly         many           may            maybe
me             mean           meanwhile      merely         might
more           moreover       most           mostly         much
must           my             myself         name           namely
nd             near           nearly         necessary      need
needs          neither        never          nevertheless   new
next           nine           no             nobody         non
none           noone          nor            normally       not
nothing        novel          now            nowhere        obviously
of             off            often          oh             ok
okay           old            on             once           one
ones           only           onto           or             other
others         otherwise      ought          our            ours
ourselves      out            outside        over           overall
own            particular     particularly   per            perhaps
placed         please         plus           possible       presumably
probably       provides       que            quite          qv
rather         rd             re             really         reasonably
regarding      regardless     regards        relatively     respectively
right          said           same           saw            say
saying         says           second         secondly       see
seeing         seem           seemed         seeming        seems
seen           self           selves         sensible       sent
serious        seriously      seven          several        shall
she            should         shouldn't      since          six
so             some           somebody       somehow        someone
something      sometime       sometimes      somewhat       somewhere
soon           sorry          specified      specify        specifying
still          sub            such           sup            sure
t's            take           taken          tell           tends
th             than           thank          thanks         thanx
that           that's         thats          the            their
theirs         them           themselves     then           thence
there          there's        thereafter     thereby        therefore
therein        theres         thereupon      these          they
they'd         they'll        they're        they've        think
third          this           thorough       thoroughly     those
though         three          through        throughout     thru
thus           to             together       too            took
toward         towards        tried          tries          truly
try            trying         twice          two            un
under          unfortunately  unless         unlikely       until
unto           up             upon           us             use
used           useful         uses           using          usually
value          various        very           via            viz
vs             want           wants          was            wasn't
way            we             we'd           we'll          we're
we've          welcome        well           went           were
weren't        what           what's         whatever       when
whence         whenever       where          where's        whereafter
whereas        whereby        wherein        whereupon      wherever
whether        which          while          whither        who
who's          whoever        whole          whom           whose
why            will           willing        wish           with
within         without        won't          wonder         would
would          wouldn't       yes            yet            you
you'd          you'll         you're         you've         your
yours          yourself       yourselves     zero           


File: manual.info,  Node: fulltext-restrictions,  Next: fulltext-fine-tuning,  Prev: fulltext-stopwords,  Up: fulltext-search

11.8.5 Full-Text Restrictions
-----------------------------

   * Full-text searches are supported for `MyISAM' tables only.

   * Full-text searches can be used with most multi-byte character
     sets. The exception is that for Unicode, the `utf8' character set
     can be used, but not the `ucs2' character set. However, although
     `FULLTEXT' indexes on `ucs2' columns cannot be used, you can
     perform `IN BOOLEAN MODE' searches on a `ucs2' column that has no
     such index.

   * Ideographic languages such as Chinese and Japanese do not have
     word delimiters. Therefore, the `FULLTEXT' parser _cannot
     determine where words begin and end in these and other such
     languages_. The implications of this and some workarounds for the
     problem are described in *Note fulltext-search::.

   * Although the use of multiple character sets within a single table
     is supported, all columns in a `FULLTEXT' index must use the same
     character set and collation.

   * The `MATCH()' column list must match exactly the column list in
     some `FULLTEXT' index definition for the table, unless this
     `MATCH()' is `IN BOOLEAN MODE'. Boolean-mode searches can be done
     on non-indexed columns, although they are likely to be slow.

   * The argument to `AGAINST()' must be a constant string.


File: manual.info,  Node: fulltext-fine-tuning,  Prev: fulltext-restrictions,  Up: fulltext-search

11.8.6 Fine-Tuning MySQL Full-Text Search
-----------------------------------------

MySQL's full-text search capability has few user-tunable parameters.
You can exert more control over full-text searching behavior if you
have a MySQL source distribution because some changes require source
code modifications. See *Note installing-source::.

Note that full-text search is carefully tuned for the most
effectiveness. Modifying the default behavior in most cases can
actually decrease effectiveness. _Do not alter the MySQL sources unless
you know what you are doing_.

Most full-text variables described in this section must be set at
server startup time. A server restart is required to change them; they
cannot be modified while the server is running.

Some variable changes require that you rebuild the `FULLTEXT' indexes
in your tables. Instructions for doing this are given at the end of
this section.

   * The minimum and maximum lengths of words to be indexed are defined
     by the `ft_min_word_len' and `ft_max_word_len' system variables.
     (See *Note server-system-variables::.) The default minimum value
     is four characters; the default maximum is version dependent. If
     you change either value, you must rebuild your `FULLTEXT' indexes.
     For example, if you want three-character words to be searchable,
     you can set the `ft_min_word_len' variable by putting the
     following lines in an option file:

          [mysqld]
          ft_min_word_len=3

     Then you must restart the server and rebuild your `FULLTEXT'
     indexes. Note particularly the remarks regarding `myisamchk' in the
     instructions following this list.

   * To override the default stopword list, set the `ft_stopword_file'
     system variable. (See *Note server-system-variables::.) The
     variable value should be the pathname of the file containing the
     stopword list, or the empty string to disable stopword filtering.
     After changing the value of this variable or the contents of the
     stopword file, restart the server and rebuild your `FULLTEXT'
     indexes.

     The stopword list is free-form. That is, you may use any
     non-alphanumeric character such as newline, space, or comma to
     separate stopwords. Exceptions are the underscore character
     (``_'') and a single apostrophe (``''') which are treated as part
     of a word. The character set of the stopword list is the server's
     default character set; see *Note charset-server::.

   * The 50% threshold for natural language searches is determined by
     the particular weighting scheme chosen. To disable it, look for
     the following line in `storage/myisam/ftdefs.h':

          #define GWS_IN_USE GWS_PROB

     Change that line to this:

          #define GWS_IN_USE GWS_FREQ

     Then recompile MySQL. There is no need to rebuild the indexes in
     this case.

     *Note*:

     By making this change, you _severely_ decrease MySQL's ability to
     provide adequate relevance values for the `MATCH()' function. If
     you really need to search for such common words, it would be
     better to search using `IN BOOLEAN MODE' instead, which does not
     observe the 50% threshold.

   * To change the operators used for boolean full-text searches, set
     the `ft_boolean_syntax' system variable. This variable can be
     changed while the server is running, but you must have the `SUPER'
     privilege to do so. No rebuilding of indexes is necessary in this
     case. See *Note server-system-variables::, which describes the
     rules governing how to set this variable.

   * If you want to change the set of characters that are considered
     word characters, you can do so in two ways.  Suppose that you want
     to treat the hyphen character ('-') as a word character. Use
     either of these methods:

        * Modify the MySQL source: In `storage/myisam/ftdefs.h', see the
          `true_word_char()' and `misc_word_char()' macros. Add `'-''
          to one of those macros and recompile MySQL.

        * Modify a character set file: This requires no recompilation.
          The `true_word_char()' macro uses a `character type' table to
          distinguish letters and numbers from other characters. .  You
          can edit the `<ctype><map>' contents in one of the character
          set XML files to specify that `'-'' is a `letter.' Then use
          the given character set for your `FULLTEXT' indexes.

     After making the modification, you must rebuild the indexes for
     each table that contains any `FULLTEXT' indexes.

If you modify full-text variables that affect indexing
(`ft_min_word_len', `ft_max_word_len', or `ft_stopword_file'), or if
you change the stopword file itself, you must rebuild your `FULLTEXT'
indexes after making the changes and restarting the server. To rebuild
the indexes in this case, it is sufficient to do a `QUICK' repair
operation:

     mysql> REPAIR TABLE TBL_NAME QUICK;

Each table that contains any `FULLTEXT' index must be repaired as just
shown. Otherwise, queries for the table may yield incorrect results,
and modifications to the table will cause the server to see the table
as corrupt and in need of repair.

Note that if you use `myisamchk' to perform an operation that modifies
table indexes (such as repair or analyze), the `FULLTEXT' indexes are
rebuilt using the _default_ full-text parameter values for minimum word
length, maximum word length, and stopword file unless you specify
otherwise. This can result in queries failing.

The problem occurs because these parameters are known only by the
server. They are not stored in `MyISAM' index files. To avoid the
problem if you have modified the minimum or maximum word length or
stopword file values used by the server, specify the same
`ft_min_word_len', `ft_max_word_len', and `ft_stopword_file' values to
`myisamchk' that you use for `mysqld'. For example, if you have set the
minimum word length to 3, you can repair a table with `myisamchk' like
this:

     shell> myisamchk --recover --ft_min_word_len=3 TBL_NAME.MYI

To ensure that `myisamchk' and the server use the same values for
full-text parameters, place each one in both the `[mysqld]' and
`[myisamchk]' sections of an option file:

     [mysqld]
     ft_min_word_len=3

     [myisamchk]
     ft_min_word_len=3

An alternative to using `myisamchk' is to use the `REPAIR TABLE',
`ANALYZE TABLE', `OPTIMIZE TABLE', or `ALTER TABLE' statements. These
statements are performed by the server, which knows the proper full-text
parameter values to use.


File: manual.info,  Node: cast-functions,  Next: xml-functions,  Prev: fulltext-search,  Up: functions

11.9 Cast Functions and Operators
=================================

*Name*                        *Description*
`BINARY'                      Cast a string to a binary string
`CAST()'                      Cast a value as a certain type
`Convert()'                   Cast a value as a certain type

   *  `BINARY'

     The `BINARY' operator casts the string following it to a binary
     string. This is an easy way to force a column comparison to be
     done byte by byte rather than character by character. This causes
     the comparison to be case sensitive even if the column isn't
     defined as `BINARY' or `BLOB'.  `BINARY' also causes trailing
     spaces to be significant.

          mysql> SELECT 'a' = 'A';
                  -> 1
          mysql> SELECT BINARY 'a' = 'A';
                  -> 0
          mysql> SELECT 'a' = 'a ';
                  -> 1
          mysql> SELECT BINARY 'a' = 'a ';
                  -> 0

     In a comparison, `BINARY' affects the entire operation; it can be
     given before either operand with the same result.

     `BINARY STR' is shorthand for `CAST(STR AS BINARY)'.

     Note that in some contexts, if you cast an indexed column to
     `BINARY', MySQL is not able to use the index efficiently.

   *  `CAST(EXPR AS TYPE)'

     The `CAST()' function takes a value of one type and produce a
     value of another type, similar to `CONVERT()'. See the description
     of `CONVERT()' for more information.

   *  `CONVERT(EXPR,TYPE)', `CONVERT(EXPR USING TRANSCODING_NAME)'

     The `CONVERT()' and `CAST()' functions take a value of one type
     and produce a value of another type.

     The TYPE can be one of the following values:

        * `BINARY[(N)]'

        * `CHAR[(N)]'

        * `DATE'

        * `DATETIME'

        * `DECIMAL[(M[,D])]'

        * `SIGNED [INTEGER]'

        * `TIME'

        * `UNSIGNED [INTEGER]'

     `BINARY' produces a string with the `BINARY' data type. See *Note
     binary-varbinary:: for a description of how this affects
     comparisons. If the optional length N is given, `BINARY(N)' causes
     the cast to use no more than N bytes of the argument. Values
     shorter than N bytes are padded with `0x00' bytes to a length of N.

     `CHAR(N)' causes the cast to use no more than N characters of the
     argument.

     `CAST()' and `CONVERT(... USING ...)' are standard SQL syntax. The
     non-`USING' form of `CONVERT()' is ODBC syntax.

     `CONVERT()' with `USING' is used to convert data between different
     character sets. In MySQL, transcoding names are the same as the
     corresponding character set names. For example, this statement
     converts the string `'abc'' in the default character set to the
     corresponding string in the `utf8' character set:

          SELECT CONVERT('abc' USING utf8);

Normally, you cannot compare a `BLOB' value or other binary string in
case-insensitive fashion because binary strings have no character set,
and thus no concept of lettercase.  To perform a case-insensitive
comparison, use the `CONVERT()' function to convert the value to a
non-binary string. If the character set of the result has a
case-insensitive collation, the `LIKE' operation is not case sensitive:

     SELECT 'A' LIKE CONVERT(BLOB_COL USING latin1) FROM TBL_NAME;

To use a different character set, substitute its name for `latin1' in
the preceding statement. To ensure that a case-insensitive collation is
used, specify a `COLLATE' clause following the `CONVERT()' call.

`CONVERT()' can be used more generally for comparing strings that are
represented in different character sets.

The cast functions are useful when you want to create a column with a
specific type in a `CREATE ... SELECT' statement:

     CREATE TABLE new_table SELECT CAST('2000-01-01' AS DATE);

The functions also can be useful for sorting `ENUM' columns in lexical
order. Normally, sorting of `ENUM' columns occurs using the internal
numeric values. Casting the values to `CHAR' results in a lexical sort:

     SELECT ENUM_COL FROM TBL_NAME ORDER BY CAST(ENUM_COL AS CHAR);

`CAST(STR AS BINARY)' is the same thing as `BINARY STR'.  `CAST(EXPR AS
CHAR)' treats the expression as a string with the default character set.

`CAST()' also changes the result if you use it as part of a more
complex expression such as `CONCAT('Date: ',CAST(NOW() AS DATE))'.

You should not use `CAST()' to extract data in different formats but
instead use string functions like `LEFT()' or `EXTRACT()'. See *Note
date-and-time-functions::.

To cast a string to a numeric value in numeric context, you normally do
not have to do anything other than to use the string value as though it
were a number:

     mysql> SELECT 1+'1';
            -> 2

If you use a number in string context, the number automatically is
converted to a `BINARY' string.

     mysql> SELECT CONCAT('hello you ',2);
             -> 'hello you 2'

MySQL supports arithmetic with both signed and unsigned 64-bit values.
If you are using numeric operators (such as `+' or `-') and one of the
operands is an unsigned integer, the result is unsigned. You can
override this by using the `SIGNED' and `UNSIGNED' cast operators to
cast the operation to a signed or unsigned 64-bit integer, respectively.

     mysql> SELECT CAST(1-2 AS UNSIGNED)
             -> 18446744073709551615
     mysql> SELECT CAST(CAST(1-2 AS UNSIGNED) AS SIGNED);
             -> -1

Note that if either operand is a floating-point value, the result is a
floating-point value and is not affected by the preceding rule. (In
this context, `DECIMAL' column values are regarded as floating-point
values.)

     mysql> SELECT CAST(1 AS UNSIGNED) - 2.0;
             -> -1.0

If you are using a string in an arithmetic operation, this is converted
to a floating-point number.

If you convert a `zero' date string to a date, `CONVERT()' and `CAST()'
return `NULL' and produce a warning when the `NO_ZERO_DATE' SQL mode is
enabled.


File: manual.info,  Node: xml-functions,  Next: other-functions,  Prev: cast-functions,  Up: functions

11.10 XML Functions
===================

*Name*                        *Description*
`ExtractValue()'(v5.1.5)      Extracts a value from an XML string using
                              XPath notation
`UpdateXML()'(v5.1.5)         Return replaced XML fragment

This section discusses XML and related functionality in MySQL.

*Note*:

It is possible to obtain XML-formatted output from MySQL in the `mysql'
and `mysqldump' clients by invoking them with the `--xml' option.  See
*Note mysql::, and *Note mysqldump::.

Beginning with MySQL 5.1.5, two functions providing basic XPath 1.0
(XML Path Language, version 1.0) capabilities are available.  Some
basic information about XPath syntax and usage is provided later in
this section; however, an in-depth discussion of these topics is beyond
the scope of this Manual, and you should refer to the XML Path Language
(XPath) 1.0 standard (http://www.w3.org/TR/xpath) for definitive
information. A useful resource for those new to XPath or who desire a
refresher in the basics is the Zvon.org XPath Tutorial
(http://www.zvon.org/xxl/XPathTutorial/), which is available in several
languages.

*Note*:

These functions remain under development. We continue to improve these
and other aspects of XML and XPath functionality in MySQL 5.1 and
onwards. You may discuss these, ask questions about them, and obtain
help from other users with them in the MySQL XML User Forum
(http://forums.mysql.com/list.php?44).

Beginning with MySQL 5.1.20, XPath expressions used with these
functions support user variables and local routine variables. User
variables are weakly checked; variables local to routines are strongly
checked (see also Bug#26518 (http://bugs.mysql.com/26518)):

   * User variables (weak checking)

     Variables using the syntax `$@VARIABLE_NAME' (that is, user
     variables) are not checked. No warnings or errors are issued by
     the server if a variable has the wrong type or has previously not
     been assigned a value. This also means the user is fully
     responsible for any typographical errors, since no warnings will
     be given if (for example) `$@myvairable' is used where
     `$@myvariable' was intended.

     Example

          mysql> SET @xml = '<a><b>X</b><b>Y</b></a>';
          Query OK, 0 rows affected (0.00 sec)

          mysql> SET @i =1, @j = 2;
          Query OK, 0 rows affected (0.00 sec)

          mysql> SELECT @i, ExtractValue(@xml, '//b[$@i]');
          +------+--------------------------------+
          | @i   | ExtractValue(@xml, '//b[$@i]') |
          +------+--------------------------------+
          |    1 | X                              |
          +------+--------------------------------+
          1 row in set (0.00 sec)

          mysql> SELECT @j, ExtractValue(@xml, '//b[$@j]');
          +------+--------------------------------+
          | @j   | ExtractValue(@xml, '//b[$@j]') |
          +------+--------------------------------+
          |    2 | Y                              |
          +------+--------------------------------+
          1 row in set (0.00 sec)

          mysql> SELECT @k, ExtractValue(@xml, '//b[$@k]');
          +------+--------------------------------+
          | @k   | ExtractValue(@xml, '//b[$@k]') |
          +------+--------------------------------+
          | NULL |                                |
          +------+--------------------------------+
          1 row in set (0.00 sec)

   * Variables in routines (strong checking)

     Variables using the syntax `$VARIABLE_NAME' can be declared and
     used with these functions when they are called inside stored
     procedures. Such variables are local to the stored procedure in
     which they are defined, and are strongly checked for type and
     value.

     Example

          mysql> DELIMITER |

          mysql> CREATE PROCEDURE myproc ()
              -> BEGIN
              ->   DECLARE i INT DEFAULT 1;
              ->   DECLARE xml VARCHAR(25) DEFAULT '<a>X</a><a>Y</a><a>Z</a>';
              ->
              ->   WHILE i < 4 DO
              ->     SELECT xml, i, ExtractValue(xml, '//a[$i]');
              ->     SET i = i+1;
              ->   END WHILE;
              -> END |
          Query OK, 0 rows affected (0.01 sec)

          mysql> DELIMITER ;

          mysql> CALL myproc;
          +--------------------------+---+------------------------------+
          | xml                      | i | ExtractValue(xml, '//a[$i]') |
          +--------------------------+---+------------------------------+
          | <a>X</a><a>Y</a><a>Z</a> | 1 | X                            |
          +--------------------------+---+------------------------------+
          1 row in set (0.00 sec)

          +--------------------------+---+------------------------------+
          | xml                      | i | ExtractValue(xml, '//a[$i]') |
          +--------------------------+---+------------------------------+
          | <a>X</a><a>Y</a><a>Z</a> | 2 | Y                            |
          +--------------------------+---+------------------------------+
          1 row in set (0.01 sec)

          +--------------------------+---+------------------------------+
          | xml                      | i | ExtractValue(xml, '//a[$i]') |
          +--------------------------+---+------------------------------+
          | <a>X</a><a>Y</a><a>Z</a> | 3 | Z                            |
          +--------------------------+---+------------------------------+
          1 row in set (0.01 sec)

     Parameters

     Variables used in XPath expressions inside stored routines that
     are passed in as parameters are also subject to strong checking.

Expressions containing user variables or variables local to routines
must otherwise (except for notation) conform to the rules for XPath
expressions containing variables as given in the XPath 1.0
specification.

*Note*:

Currently, a user variable used to store an XPath expression is treated
as an empty string. Because of this, it is not possible to store an
XPath expression as a user variable. We intend to fix this issue in a
future MySQL release. (Bug#32911 (http://bugs.mysql.com/32911))

   *  `ExtractValue(XML_FRAG, XPATH_EXPR)'

     `ExtractValue()' takes two string arguments, a fragment of XML
     markup XML_FRAG and an XPath expression XPATH_EXPR (also known as a
     _locator_); it returns the text (`CDATA') of the first text node
     which is a child of the element(s) matched by the XPath
     expression. It is the equivalent of performing a match using the
     XPATH_EXPR after appending `/text()'. In other words,
     `ExtractValue('<a><b>Sakila</b></a>', '/a/b')' and
     `ExtractValue('<a><b>Sakila</b></a>', '/a/b/text()')' produce the
     same result.

     If multiple matches are found, then the content of the first child
     text node of each matching element is returned (in the order
     matched) as a single, space-delimited string.

     If no matching text node is found for the expression (including
     the implicit `/text()') -- for whatever reason, as long as
     XPATH_EXPR is valid, and XML_FRAG consists of elements which are
     properly nested and closed -- an empty string is returned. No
     distinction is made between a match on an empty element and no
     match at all. This is by design.

     If you need to determine whether no matching element was found in
     XML_FRAG or such an element was found but contained no child text
     nodes, you should test the result of an expression that uses the
     XPath `count()' function. For example, both of these statements
     return an empty string, as shown here:

          mysql> SELECT ExtractValue('<a><b/></a>', '/a/b');
          +-------------------------------------+
          | ExtractValue('<a><b/></a>', '/a/b') |
          +-------------------------------------+
          |                                     |
          +-------------------------------------+
          1 row in set (0.00 sec)

          mysql> SELECT ExtractValue('<a><c/></a>', '/a/b');
          +-------------------------------------+
          | ExtractValue('<a><c/></a>', '/a/b') |
          +-------------------------------------+
          |                                     |
          +-------------------------------------+
          1 row in set (0.00 sec)

     However, you can determine whether there was actually a matching
     element using the following:

          mysql> SELECT ExtractValue('<a><b/></a>', 'count(/a/b)');
          +-------------------------------------+
          | ExtractValue('<a><b/></a>', 'count(/a/b)') |
          +-------------------------------------+
          | 1                                   |
          +-------------------------------------+
          1 row in set (0.00 sec)

          mysql> SELECT ExtractValue('<a><c/></a>', 'count(/a/b)');
          +-------------------------------------+
          | ExtractValue('<a><c/></a>', 'count(/a/b)') |
          +-------------------------------------+
          | 0                                   |
          +-------------------------------------+
          1 row in set (0.01 sec)

     *Important*:

     `ExtractValue()' returns only `CDATA', and does not return any
     tags that might be contained within a matching tag, nor any of
     their content (see the result returned as `val1' in the following
     example).

          mysql> SELECT
              ->   ExtractValue('<a>ccc<b>ddd</b></a>', '/a') AS val1,
              ->   ExtractValue('<a>ccc<b>ddd</b></a>', '/a/b') AS val2,
              ->   ExtractValue('<a>ccc<b>ddd</b></a>', '//b') AS val3,
              ->   ExtractValue('<a>ccc<b>ddd</b></a>', '/b') AS val4,
              ->   ExtractValue('<a>ccc<b>ddd</b><b>eee</b></a>', '//b') AS val5;

          +------+------+------+------+---------+
          | val1 | val2 | val3 | val4 | val5    |
          +------+------+------+------+---------+
          | ccc  | ddd  | ddd  |      | ddd eee |
          +------+------+------+------+---------+

     Beginning with MySQL 5.1.8, this function uses the current SQL
     collation for making comparisons with `contains()', performing the
     same collation aggregation as other string functions (such as
     `CONCAT()'), in taking into account the collation coercibility of
     their arguments; see *Note charset-collate-tricky::, for an
     explanation of the rules governing this behavior.

     (Previously, binary -- that is, case-sensitive -- comparison was
     always used.)

     Beginning with MySQL 5.1.12, `NULL' is returned if XML_FRAG
     contains elements which are not properly nested or closed, and a
     warning is generated, as shown in this example:

          mysql> SELECT ExtractValue('<a>c</a><b', '//a');
          +-----------------------------------+
          | ExtractValue('<a>c</a><b', '//a') |
          +-----------------------------------+
          | NULL                              |
          +-----------------------------------+
          1 row in set, 1 warning (0.00 sec)

          mysql> SHOW WARNINGS;
          +---------+------+-------------------------------------------------------------------------------------------+
          | Level   | Code | Message                                                                                   |
          +---------+------+-------------------------------------------------------------------------------------------+
          | Warning | 1523 | Incorrect XML value: 'parse error at line 1 pos 11: END-OF-INPUT unexpected ('>' wanted)' |
          +---------+------+-------------------------------------------------------------------------------------------+
          1 row in set (0.00 sec)

          mysql> SELECT ExtractValue('<a>c</a><b/>', '//a');
          +-------------------------------------+
          | ExtractValue('<a>c</a><b/>', '//a') |
          +-------------------------------------+
          | c                                   |
          +-------------------------------------+
          1 row in set (0.00 sec)

     Prior to MySQL 5.1.12, an empty string was returned in such cases.
     (Bug#18201 (http://bugs.mysql.com/18201))

   *  `UpdateXML(XML_TARGET, XPATH_EXPR, NEW_XML)'

     This function replaces a single portion of a given fragment of XML
     markup XML_TARGET with a new XML fragment NEW_XML, and then
     returns the changed XML. The portion of XML_TARGET that is
     replaced matches an XPath expression XPATH_EXPR supplied by the
     user. If no expression matching XPATH_EXPR is found, or if multiple
     matches are found, the function returns the original XML_TARGET
     XML fragment. All three arguments should be strings.

          mysql> SELECT
              ->   UpdateXML('<a><b>ccc</b><d></d></a>', '/a', '<e>fff</e>') AS val1,
              ->   UpdateXML('<a><b>ccc</b><d></d></a>', '/b', '<e>fff</e>') AS val2,
              ->   UpdateXML('<a><b>ccc</b><d></d></a>', '//b', '<e>fff</e>') AS val3,
              ->   UpdateXML('<a><b>ccc</b><d></d></a>', '/a/d', '<e>fff</e>') AS val4,
              ->   UpdateXML('<a><d></d><b>ccc</b><d></d></a>', '/a/d', '<e>fff</e>') AS val5
              -> \G

          *************************** 1. row ***************************
          val1: <e>fff</e>
          val2: <a><b>ccc</b><d></d></a>
          val3: <a><e>fff</e><d></d></a>
          val4: <a><b>ccc</b><e>fff</e></a>
          val5: <a><d></d><b>ccc</b><d></d></a>

*Note*:

A discussion in depth of XPath syntax and usage are beyond the scope of
this Manual. Please see the XML Path Language (XPath) 1.0 specification
(http://www.w3.org/TR/xpath) for definitive information. A useful
resource for those new to XPath or who are wishing a refresher in the
basics is the Zvon.org XPath Tutorial
(http://www.zvon.org/xxl/XPathTutorial/), which is available in several
languages.

Descriptions and examples of some basic XPath expressions follow:

   * `/TAG'

     Matches `<TAG/>' if and only if `<TAG/>' is the root element.

     Example: `/a' has a match in `<a><b/></a>' because it matches the
     outermost (root) tag. It does not match the inner A element in
     `<b><a/></b>' because in this instance it is the child of another
     element.

   * `/TAG1/TAG2'

     Matches `<TAG2/>' if and only if it is a child of `<TAG1/>', and
     `<TAG1/>' is the root element.

     Example: `/a/b' matches the B element in the XML fragment
     `<a><b/></a>' because it is a child of the root element A. It does
     not have a match in `<b><a/></b>' because in this case, B is the
     root element (and hence the child of no other element). Nor does
     the XPath expression have a match in `<a><c><b/></c></a>'; here, B
     is a descendant of A, but not actually a child of A.

     This construct is extendable to three or more elements. For
     example, the XPath expression `/a/b/c' matches the C element in the
     fragment `<a><b><c/></b></a>'.

   * `//TAG'

     Matches any instance of `<TAG>'.

     Example: `//a' matches the A element in any of the following:
     `<a><b><c/></b></a>'; `<c><a><b/></a></b>'; `<c><b><a/></b></c>'.

     `//' can be combined with `/'. For example, `//a/b' matches the B
     element in either of the fragments `<a><b/></a>' or
     `<a><b><c/></b></a>'

     *Note*:

     `//TAG' is the equivalent of `/descendant-or-self::*/TAG'.  A
     common error is to confuse this with `/descendant-or-self::TAG',
     although the latter expression can actually lead to very different
     results, as can be seen here:

          mysql> SET @xml = '<a><b><c>w</c><b>x</b><d>y</d>z</b></a>';
          Query OK, 0 rows affected (0.00 sec)

          mysql> SELECT @xml;
          +-----------------------------------------+
          | @xml                                    |
          +-----------------------------------------+
          | <a><b><c>w</c><b>x</b><d>y</d>z</b></a> |
          +-----------------------------------------+
          1 row in set (0.00 sec)

          mysql> SELECT ExtractValue(@xml, '//b[1]');
          +------------------------------+
          | ExtractValue(@xml, '//b[1]') |
          +------------------------------+
          | x z                          |
          +------------------------------+
          1 row in set (0.00 sec)

          mysql> SELECT ExtractValue(@xml, '//b[2]');
          +------------------------------+
          | ExtractValue(@xml, '//b[2]') |
          +------------------------------+
          |                              |
          +------------------------------+
          1 row in set (0.01 sec)

          mysql> SELECT ExtractValue(@xml, '/descendant-or-self::*/b[1]');
          +---------------------------------------------------+
          | ExtractValue(@xml, '/descendant-or-self::*/b[1]') |
          +---------------------------------------------------+
          | x z                                               |
          +---------------------------------------------------+
          1 row in set (0.06 sec)

          mysql> SELECT ExtractValue(@xml, '/descendant-or-self::*/b[2]');
          +---------------------------------------------------+
          | ExtractValue(@xml, '/descendant-or-self::*/b[2]') |
          +---------------------------------------------------+
          |                                                   |
          +---------------------------------------------------+
          1 row in set (0.00 sec)

          mysql> SELECT ExtractValue(@xml, '/descendant-or-self::b[1]');
          +-------------------------------------------------+
          | ExtractValue(@xml, '/descendant-or-self::b[1]') |
          +-------------------------------------------------+
          | z                                               |
          +-------------------------------------------------+
          1 row in set (0.00 sec)

          mysql> SELECT ExtractValue(@xml, '/descendant-or-self::b[2]');
          +-------------------------------------------------+
          | ExtractValue(@xml, '/descendant-or-self::b[2]') |
          +-------------------------------------------------+
          | x                                               |
          +-------------------------------------------------+
          1 row in set (0.00 sec)

   * The `*' operator acts as a `wildcard' that matches any element.
     For example, the expression `/*/b' matches the B element in either
     of the XML fragments `<a><b/></a>' or `<c><b/></c>'. However, the
     expression does not produce a match in the fragment `<b><a/></b>'
     because B must be a child of some other element. The wildcard may
     be used in any position: The expression `/*/b/*' will match any
     child of a B element that is itself not the root element.

   * You can match any of several locators using the `|' (`UNION')
     operator. For example, the expression `//b|//c' matches all B and C
     elements in the XML target.

   * It is also possible to match an element based on the value of one
     or more of its attributes. This done using the syntax
     `TAG[@ATTRIBUTE="VALUE"]'.  For example, the expression
     `//b[@id="idB"]' matches the second B element in the fragment
     `<a><b id="idA"/><c/><b id="idB"/></a>'. To match against _any_
     element having `ATTRIBUTE="VALUE"', use the XPath expression
     `//*[ATTRIBUTE="VALUE"]'.

     To filter multiple attribute values, simply use multiple
     attribute-comparison clauses in succession. For example, the
     expression `//b[@c="x"][@d="y"]' matches the element `<b c="x"
     d="y"/>' occurring anywhere in a given XML fragment.

     To find elements for which the same attribute matches any of
     several values, you can use multiple locators joined by the `|'
     operator. For example, to match all B elements whose C attributes
     have either of the values 23 or 17, use the expression
     `//b[@c="23"]|//b[@c="17"]'. You can also use the logical `or'
     operator for this purpose: `//b[@c="23" or @c="17"]'.

     *Note*:

     The difference between `or' and `|' is that `or' joins conditions,
     while `|' joins result sets.

XPath Limitations

The XPath syntax supported by these functions is currently subject to
the following limitations:

   * Nodeset-to-nodeset comparison (such as `'/a/b[@c=@d]'') is not
     supported.

   * Prior to MySQL 5.1.14, equality and inequality (`=' and `!=') were
     the only supported comparison operators. Beginning with MySQL
     5.1.14, all of the standard XPath comparison operators are
     supported. (Bug#22823 (http://bugs.mysql.com/22823))

   * Relative locator expressions are resolved in the context of the
     root node. For example, consider the following query and result:

          mysql> SELECT ExtractValue(
              ->   '<a><b c="1">X</b><b c="2">Y</b></a>',
              ->    'a/b'
              -> ) AS result;
          +--------+
          | result |
          +--------+
          | X Y    |
          +--------+
          1 row in set (0.03 sec)

     In this case, the locator `a/b' resolves to `/a/b'.

     Relative locators are also supported within predicates. In the
     following example, `d[../@c="1"]' is resolved as `/a/b[@c="1"]/d':

          mysql> SELECT ExtractValue(
              ->      '<a>
              ->        <b c="1"><d>X</d></b>
              ->        <b c="2"><d>X</d></b>
              ->      </a>',
              ->      'a/b/d[../@c="1"]')
              -> AS result;
          +--------+
          | result |
          +--------+
          | X      |
          +--------+
          1 row in set (0.00 sec)

   * The `::' operator is not supported in combination with node types
     such as the following:

        * `AXIS::comment()'

        * `AXIS::text()'

        * `AXIS::processing-instructions()'

        * `AXIS::node()'

     However, name tests (such as `AXIS::NAME' and `AXIS::*') are
     supported, as shown in these examples:

          mysql> SELECT ExtractValue('<a><b>x</b><c>y</c></a>','/a/child::b');
          +-------------------------------------------------------+
          | ExtractValue('<a><b>x</b><c>y</c></a>','/a/child::b') |
          +-------------------------------------------------------+
          | x                                                     |
          +-------------------------------------------------------+
          1 row in set (0.02 sec)

          mysql> SELECT ExtractValue('<a><b>x</b><c>y</c></a>','/a/child::*');
          +-------------------------------------------------------+
          | ExtractValue('<a><b>x</b><c>y</c></a>','/a/child::*') |
          +-------------------------------------------------------+
          | x y                                                   |
          +-------------------------------------------------------+
          1 row in set (0.01 sec)

   * `Up-and-down' navigation is not supported in cases where the path
     would lead `above' the root element. That is, you cannot use
     expressions which match on descendants of ancestors of a given
     element, where one or more of the ancestors of the current element
     is also an ancestor of the root element (see Bug#16321
     (http://bugs.mysql.com/16321)).

   * The following XPath functions are not supported, or have known
     issues as indicated:

        * Prior to MySQL 5.1.24, the `boolean()' function did not
          produce correct results for some string and nodeset values,
          including the `NULL' string (see Bug#26051
          (http://bugs.mysql.com/26051)).

        * `id()'

        * `lang()'

        * Prior to MySQL 5.1.8, the `last()' function was not supported
          (see Bug#16318 (http://bugs.mysql.com/16318)).

        * `local-name()'

        * `name()'

        * `namespace-uri()'

        * `normalize-space()'

        * `starts-with()'

        * `string()'

        * `substring-after()'

        * `substring-before()'

        * `translate()'

   * The following axes are not supported:

        * `following-sibling'

        * `following'

        * `preceding-sibling'

        * `preceding'

Beginning with MySQL 5.1.10, XPath expressions passed as arguments to
`ExtractValue()' and `UpdateXML()' may contain the colon character
(``:'') in element selectors, which enables their use with markup
employing XML namespaces notation. For example:

     mysql> SET @xml = '<a>111<b:c>222<d>333</d><e:f>444</e:f></b:c></a>';
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT ExtractValue(@xml, '//e:f');
     +-----------------------------+
     | ExtractValue(@xml, '//e:f') |
     +-----------------------------+
     | 444                         |
     +-----------------------------+
     1 row in set (0.00 sec)

     mysql> SELECT UpdateXML(@xml, '//b:c', '<g:h>555</g:h>');
     +--------------------------------------------+
     | UpdateXML(@xml, '//b:c', '<g:h>555</g:h>') |
     +--------------------------------------------+
     | <a>111<g:h>555</g:h></a>                   |
     +--------------------------------------------+
     1 row in set (0.00 sec)

This is similar in some respects to what is allowed by Apache Xalan
(http://xalan.apache.org/) and some other parsers, and is much simpler
than requiring namespace declarations or the use of the
`namespace-uri()' and `local-name()' functions.

Error handling

For both `ExtractValue()' and `UpdateXML()', the XPath locator used
must be valid and the XML to be searched must consist of elements which
are properly nested and closed. If the locator is invalid, an error is
generated:

     mysql> SELECT ExtractValue('<a>c</a><b/>', '/&a');
     `ERROR 1105 (HY000): XPATH syntax error: '&a''

If XML_FRAG does not consist of elements which are properly nested and
closed, then `NULL' is returned, and a warning is generated, as shown
in this example:

     mysql> SELECT ExtractValue('<a>c</a><b', '//a');
     +-----------------------------------+
     | ExtractValue('<a>c</a><b', '//a') |
     +-----------------------------------+
     | NULL                              |
     +-----------------------------------+
     1 row in set, 1 warning (0.00 sec)

     mysql> SHOW WARNINGS;
     +---------+------+-------------------------------------------------------------------------------------------+
     | Level   | Code | Message                                                                                   |
     +---------+------+-------------------------------------------------------------------------------------------+
     | Warning | 1523 | Incorrect XML value: 'parse error at line 1 pos 11: END-OF-INPUT unexpected ('>' wanted)' |
     +---------+------+-------------------------------------------------------------------------------------------+
     1 row in set (0.00 sec)

     mysql> SELECT ExtractValue('<a>c</a><b/>', '//a');
     +-------------------------------------+
     | ExtractValue('<a>c</a><b/>', '//a') |
     +-------------------------------------+
     | c                                   |
     +-------------------------------------+
     1 row in set (0.00 sec)

Prior to MySQL 5.1.12, an empty string was returned in such cases.
(Bug#18201 (http://bugs.mysql.com/18201))

*Important*:

The replacement XML used as the third argument to `UpdateXML()' is
_not_ checked to determine whether it consists solely of elements which
are properly nested and closed.

XPath Injection

_code injection_ occurs when malicious code is introduced into the
system to gain unauthorized access to privileges and data. It is based
on exploiting assumptions made by developers about the type and content
of data input from users. XPath is no exception in this regard.

A common scenario in which this can happen is the case of application
which handles authorization by matching the combination of a login name
and password with those found in an XML file, using an XPath expression
like this one:

     //user[login/text()='neapolitan' and password/text()='1c3cr34m']/attribute::id

This is the XPath equivalent of an SQL statement like this one:

     SELECT id FROM users WHERE login='neapolitan' AND password='1c3cr34m';

A PHP application employing XPath might handle the login process like
this:

     <?php

       $file     =   "users.xml";

       $login    =   $POST["login"];
       $password =   $POST["password"];

       $xpath = "//user[login/text()=$login and password/text()=$password]/attribute::id";

       if( file_exists($file) )
       {
         $xml = simplexml_load_file($file);

         if($result = $xml->xpath($xpath))
           echo "You are now logged in as user $result[0].";
         else
           echo "Invalid login name or password.";
       }
       else
         exit("Failed to open $file.");

     ?>

No checks are performed on the input. This means that a malevolent user
can `short-circuit' the test by entering `' or 1=1' for both the login
name and password, resulting in $xpath being evaluated as shown here:

     //user[login/text()='' or 1=1 and password/text()='' or 1=1]/attribute::id

Since the expression inside the square brackets always evaluates as
`true', it is effectively the same as this one, which matches the `id'
attribute of every `user' element in the XML document:

     //user/attribute::id

One way in which this particular attack can be circumvented is simply
by quoting the variable names to be interpolated in the definition of
`$xpath', forcing the values passed from a Web form to be converted to
strings:

     $xpath = "//user[login/text()='$login' and password/text()='$password']/attribute::id";

This is the same strategy that is often recommended for preventing SQL
injection attacks. In general, the practices you should follow for
preventing XPath injection attacks are the same as for preventing SQL
injection:

   * Never accepted untested data from users in your application.

   * Check all user-submited data for type; reject or convert data that
     is of the wrong type

   * Test numerical data for out of range values; truncate, round, or
     reject values that are out of range. Test strings for illegal
     characters and either strip them out or reject input containing
     them.

   * Do not output explicit error messages that might provide an
     unauthorized user with clues that could be used to compromise the
     system; log these to a file or database table instead.

Just as SQL injection attacks can be used to obtain information about
database schemas, so can XPath injection be used to traverse XML files
to uncover their structure, as discussed in Amit Klein's paper Blind
XPath Injection
(http://www.packetstormsecurity.org/papers/bypass/Blind_XPath_Injection_20040518.pdf)
(PDF file, 46KB).

It is also important to check the output being sent back to the client.
Consider what can happen when we use the MySQL `ExtractValue()'
function:

     mysql> SELECT ExtractValue(
         ->     LOAD_FILE('users.xml'),
         ->     '//user[login/text()="" or 1=1 and password/text()="" or 1=1]/attribute::id'
         -> ) AS id;
     +-------------------------------+
     | id                            |
     +-------------------------------+
     | 00327 13579 02403 42354 28570 |
     +-------------------------------+
     1 row in set (0.01 sec)

Because `ExtractValue()' returns multiple matches as a single
space-delimited string, this injection attack provides every valid ID
contained within `users.xml' to the user as a single row of output. As
an extra safeguard, you should also test output before returning it to
the user. Here is a simple example:

     mysql> SELECT @id = ExtractValue(
         ->     LOAD_FILE('users.xml'),
         ->     '//user[login/text()="" or 1=1 and password/text()="" or 1=1]/attribute::id'
         -> );
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT IF(
         ->     INSTR(@id, ' ') = 0,
         ->     @id,
         ->     'Unable to retrieve user ID')
         -> AS singleID;
     +----------------------------+
     | singleID                   |
     +----------------------------+
     | Unable to retrieve user ID |
     +----------------------------+
     1 row in set (0.00 sec)

In general, the guidelines for returning data to users securely are the
same as for accepting user input. These can be summed up as:

   * Always test outgoing data for type and allowable values.

   * Never allow unauthorized users to view error messages that might
     provide information about the application that could be used to
     exploit it.


File: manual.info,  Node: other-functions,  Next: group-by-functions-and-modifiers,  Prev: xml-functions,  Up: functions

11.11 Other Functions
=====================

* Menu:

* bit-functions::                Bit Functions
* encryption-functions::         Encryption and Compression Functions
* information-functions::        Information Functions
* miscellaneous-functions::      Miscellaneous Functions

*Name*                        *Description*
`AES_DECRYPT()'               Decrypt using AES
`AES_ENCRYPT()'               Encrypt using AES
`BENCHMARK()'                 Repeatedly execute an expression
`BIT_COUNT()'                 Return the number of bits that are set
`&'                           Bitwise AND
`~'                           Invert bits
`|'                           Bitwise OR
`^'                           Bitwise XOR
`CHARSET()'(v4.1.0)           Return the character set of the argument
`COERCIBILITY()'(v4.1.1)      Return the collation coercibility value of
                              the string  argument
`COLLATION()'(v4.1.0)         Return the collation of the string argument
`COMPRESS()'(v4.1.1)          Return result as a binary string
`CONNECTION_ID()'             Return the connection ID (thread ID)   for
                              the connection
`CURRENT_USER()',             Return the username and hostname
`CURRENT_USER'                combination
`DATABASE()'                  Return the default (current) database name
`DECODE()'                    Decodes a string encrypted using ENCODE()
`DEFAULT()'                   Return the default value for a table column
`DES_DECRYPT()'               Decrypt a string
`DES_ENCRYPT()'               Encrypt a string
`ENCODE()'                    Encode a string
`ENCRYPT()'                   Encrypt a string
`FOUND_ROWS()'                For a SELECT with a LIMIT clause, the
                              number of rows that would be returned were
                              there no LIMIT clause
`GET_LOCK()'                  Get a named lock
`INET_ATON()'                 Return the numeric value of an IP address
`INET_NTOA()'                 Return the IP address from a numeric value
`IS_FREE_LOCK()'              Checks whether the named lock  is free
`IS_USED_LOCK()'(v4.1.0)      Checks whether the named lock is in use.
                              Return connection identifier if true.
`LAST_INSERT_ID()'            Value of the AUTOINCREMENT column   for
                              the last INSERT
`<<'                          Left shift
`MASTER_POS_WAIT()'           Block until the slave has read and
                              applied all updates up to the specified
                              position
`MD5()'                       Calculate MD5 checksum
`NAME_CONST()'(v5.0.12)       Causes the column to have the given name
`OLD_PASSWORD()'(v4.1)        Return the value of the  old (pre-4.1)
                              implementation of PASSWORD
`PASSWORD()'                  Calculate and return a password string
`RAND()'                      Return a random floating-point value
`RELEASE_LOCK()'              Releases the named lock
`>>'                          Right shift
`ROW_COUNT()'(v5.0.1)         The number of rows  updated
`SCHEMA()'(v5.0.2)            A synonym for DATABASE()
`SESSION_USER()'              Synonym for USER()
`SHA1()', `SHA()'             Calculate an SHA-1 160-bit checksum
`SLEEP()'(v5.0.12)            Sleep for a number of seconds
`SYSTEM_USER()'               Synonym for USER()
`UNCOMPRESS()'(v4.1.1)        Uncompress a string compressed
`UNCOMPRESSED_LENGTH()'(v4.1.1)Return the length of a string before
                              compression
`USER()'                      Return the current username and hostname
`UUID_SHORT()'(v5.1.20)       Return an integer-valued universal
                              identifier
`UUID()'(v4.1.2)              Return a Universal Unique Identifier (UUID)
`VALUES()'(v4.1.1)            Defines the values to be used during an
                              INSERT
`VERSION()'                   Returns a string that indicates the MySQL
                              server version


File: manual.info,  Node: bit-functions,  Next: encryption-functions,  Prev: other-functions,  Up: other-functions

11.11.1 Bit Functions
---------------------

*Name*                        *Description*
`BIT_COUNT()'                 Return the number of bits that are set
`&'                           Bitwise AND
`~'                           Invert bits
`|'                           Bitwise OR
`^'                           Bitwise XOR
`<<'                          Left shift
`>>'                          Right shift

MySQL uses `BIGINT' (64-bit) arithmetic for bit operations, so these
operators have a maximum range of 64 bits.

   *  `|'

     Bitwise OR:

          mysql> SELECT 29 | 15;
                  -> 31

     The result is an unsigned 64-bit integer.

   *  `&'

     Bitwise AND:

          mysql> SELECT 29 & 15;
                  -> 13

     The result is an unsigned 64-bit integer.

   *  `^'

     Bitwise XOR:

          mysql> SELECT 1 ^ 1;
                  -> 0
          mysql> SELECT 1 ^ 0;
                  -> 1
          mysql> SELECT 11 ^ 3;
                  -> 8

     The result is an unsigned 64-bit integer.

   *  `<<'

     Shifts a longlong (`BIGINT') number to the left.

          mysql> SELECT 1 << 2;
                  -> 4

     The result is an unsigned 64-bit integer.

   *  `>>'

     Shifts a longlong (`BIGINT') number to the right.

          mysql> SELECT 4 >> 2;
                  -> 1

     The result is an unsigned 64-bit integer.

   *  `~'

     Invert all bits.

          mysql> SELECT 5 & ~1;
                  -> 4

     The result is an unsigned 64-bit integer.

   *  `BIT_COUNT(N)'

     Returns the number of bits that are set in the argument N.

          mysql> SELECT BIT_COUNT(29), BIT_COUNT(b'101010');
                  -> 4, 3


File: manual.info,  Node: encryption-functions,  Next: information-functions,  Prev: bit-functions,  Up: other-functions

11.11.2 Encryption and Compression Functions
--------------------------------------------

*Name*                        *Description*
`AES_DECRYPT()'               Decrypt using AES
`AES_ENCRYPT()'               Encrypt using AES
`COMPRESS()'(v4.1.1)          Return result as a binary string
`DECODE()'                    Decodes a string encrypted using ENCODE()
`DES_DECRYPT()'               Decrypt a string
`DES_ENCRYPT()'               Encrypt a string
`ENCODE()'                    Encode a string
`ENCRYPT()'                   Encrypt a string
`MD5()'                       Calculate MD5 checksum
`OLD_PASSWORD()'(v4.1)        Return the value of the  old (pre-4.1)
                              implementation of PASSWORD
`PASSWORD()'                  Calculate and return a password string
`SHA1()', `SHA()'             Calculate an SHA-1 160-bit checksum
`UNCOMPRESS()'(v4.1.1)        Uncompress a string compressed
`UNCOMPRESSED_LENGTH()'(v4.1.1)Return the length of a string before
                              compression

*Note*:

The encryption and compression functions return binary strings. For
many of these functions, the result might contain arbitrary byte
values. If you want to store these results, use a column with a
`VARBINARY' or `BLOB' binary string data type. This will avoid
potential problems with trailing space removal or character set
conversion that would change data values, such as may occur if you use
a non-binary string data type (`CHAR', `VARCHAR', `TEXT').

*Note*:

Exploits for the MD5 and SHA-1 algorithms have become known.  You may
wish to consider using one of the other encryption functions described
in this section instead.

   *  `AES_DECRYPT(CRYPT_STR,KEY_STR)'

     This function allows decryption of data using the official AES
     (Advanced Encryption Standard) algorithm. For more information,
     see the description of `AES_ENCRYPT()'.

   *  `AES_ENCRYPT(STR,KEY_STR)'

     `AES_ENCRYPT()' and `AES_DECRYPT()' allow encryption and
     decryption of data using the official AES (Advanced Encryption
     Standard) algorithm, previously known as `Rijndael.' Encoding with
     a 128-bit key length is used, but you can extend it up to 256 bits
     by modifying the source. We chose 128 bits because it is much
     faster and it is secure enough for most purposes.

     `AES_ENCRYPT()' encrypts a string and returns a binary string.
     `AES_DECRYPT()' decrypts the encrypted string and returns the
     original string. The input arguments may be any length. If either
     argument is `NULL', the result of this function is also `NULL'.

     Because AES is a block-level algorithm, padding is used to encode
     uneven length strings and so the result string length may be
     calculated using this formula:

          16 x (trunc(STRING_LENGTH / 16) + 1)

     If `AES_DECRYPT()' detects invalid data or incorrect padding, it
     returns `NULL'. However, it is possible for `AES_DECRYPT()' to
     return a non-`NULL' value (possibly garbage) if the input data or
     the key is invalid.

     You can use the AES functions to store data in an encrypted form
     by modifying your queries:

          INSERT INTO t VALUES (1,AES_ENCRYPT('text','password'));

     `AES_ENCRYPT()' and `AES_DECRYPT()' can be considered the most
     cryptographically secure encryption functions currently available
     in MySQL.

   *  `COMPRESS(STRING_TO_COMPRESS)'

     Compresses a string and returns the result as a binary string.
     This function requires MySQL to have been compiled with a
     compression library such as `zlib'.  Otherwise, the return value
     is always `NULL'. The compressed string can be uncompressed with
     `UNCOMPRESS()'.

          mysql> SELECT LENGTH(COMPRESS(REPEAT('a',1000)));
                  -> 21
          mysql> SELECT LENGTH(COMPRESS(''));
                  -> 0
          mysql> SELECT LENGTH(COMPRESS('a'));
                  -> 13
          mysql> SELECT LENGTH(COMPRESS(REPEAT('a',16)));
                  -> 15

     The compressed string contents are stored the following way:

        * Empty strings are stored as empty strings.

        * Non-empty strings are stored as a four-byte length of the
          uncompressed string (low byte first), followed by the
          compressed string. If the string ends with space, an extra
          ``.'' character is added to avoid problems with endspace
          trimming should the result be stored in a `CHAR' or `VARCHAR'
          column. (However, use of non-binary string data types such as
          `CHAR' or `VARCHAR' to store compressed strings is not
          recommended anyway because character set conversion may
          occur. Use a `VARBINARY' or `BLOB' binary string column
          instead.)

   *  `DECODE(CRYPT_STR,PASS_STR)'

     Decrypts the encrypted string CRYPT_STR using PASS_STR as the
     password.  CRYPT_STR should be a string returned from `ENCODE()'.

   *  `ENCODE(STR,PASS_STR)'

     Encrypt STR using PASS_STR as the password. To decrypt the result,
     use `DECODE()'.

     The result is a binary string of the same length as STR.

     The strength of the encryption is based on how good the random
     generator is. It should suffice for short strings.

   *  `DES_DECRYPT(CRYPT_STR[,KEY_STR])'

     Decrypts a string encrypted with `DES_ENCRYPT()'. If an error
     occurs, this function returns `NULL'.

     This function works only if MySQL has been configured with SSL
     support. See *Note secure-connections::.

     If no KEY_STR argument is given, `DES_DECRYPT()' examines the
     first byte of the encrypted string to determine the DES key number
     that was used to encrypt the original string, and then reads the
     key from the DES key file to decrypt the message. For this to
     work, the user must have the `SUPER' privilege. The key file can be
     specified with the `--des-key-file' server option.

     If you pass this function a KEY_STR argument, that string is used
     as the key for decrypting the message.

     If the CRYPT_STR argument does not appear to be an encrypted
     string, MySQL returns the given CRYPT_STR.

   *  `DES_ENCRYPT(STR[,{KEY_NUM|KEY_STR}])'

     Encrypts the string with the given key using the Triple-DES
     algorithm.

     This function works only if MySQL has been configured with SSL
     support. See *Note secure-connections::.

     The encryption key to use is chosen based on the second argument
     to `DES_ENCRYPT()', if one was given. With no argument, the first
     key from the DES key file is used. With a KEY_NUM argument, the
     given key number (0-9) from the DES key file is used. With a
     KEY_STR argument, the given key string is used to encrypt STR.

     The key file can be specified with the `--des-key-file' server
     option.

     The return string is a binary string where the first character is
     `CHAR(128 | KEY_NUM)'. If an error occurs, `DES_ENCRYPT()' returns
     `NULL'.

     The 128 is added to make it easier to recognize an encrypted key.
     If you use a string key, KEY_NUM is 127.

     The string length for the result is given by this formula:

          NEW_LEN = ORIG_LEN + (8 - (ORIG_LEN % 8)) + 1

     Each line in the DES key file has the following format:

          KEY_NUM DES_KEY_STR

     Each KEY_NUM value must be a number in the range from `0' to `9'.
     Lines in the file may be in any order.  DES_KEY_STR is the string
     that is used to encrypt the message. There should be at least one
     space between the number and the key. The first key is the default
     key that is used if you do not specify any key argument to
     `DES_ENCRYPT()'.

     You can tell MySQL to read new key values from the key file with
     the `FLUSH DES_KEY_FILE' statement.  This requires the `RELOAD'
     privilege.

     One benefit of having a set of default keys is that it gives
     applications a way to check for the existence of encrypted column
     values, without giving the end user the right to decrypt those
     values.

          mysql> SELECT customer_address FROM customer_table
               > WHERE crypted_credit_card = DES_ENCRYPT('credit_card_number');

   *  `ENCRYPT(STR[,SALT])'

     Encrypts STR using the Unix `crypt()' system call and returns a
     binary string. The SALT argument should be a string with at least
     two characters. If no SALT argument is given, a random value is
     used.

          mysql> SELECT ENCRYPT('hello');
                  -> 'VxuFAJXVARROc'

     `ENCRYPT()' ignores all but the first eight characters of STR, at
     least on some systems.  This behavior is determined by the
     implementation of the underlying `crypt()' system call.

     The use of `ENCRYPT()' with multi-byte character sets other than
     `utf8' is not recommended because the system call expects a string
     terminated by a zero byte.

     If `crypt()' is not available on your system (as is the case with
     Windows), `ENCRYPT()' always returns `NULL'.

   *  `MD5(STR)'

     Calculates an MD5 128-bit checksum for the string. The value is
     returned as a binary string of 32 hex digits, or `NULL' if the
     argument was `NULL'. The return value can, for example, be used as
     a hash key.

          mysql> SELECT MD5('testing');
                  -> 'ae2b1fca515949e5d54fb22b8ed95575'

     This is the `RSA Data Security, Inc. MD5 Message-Digest Algorithm.'

     If you want to convert the value to uppercase, see the description
     of binary string conversion given in the entry for the `BINARY'
     operator in *Note cast-functions::.

     See the note regarding the MD5 algorithm at the beginning this
     section.

   *  `OLD_PASSWORD(STR)'

     `OLD_PASSWORD()' was added to MySQL when the implementation of
     `PASSWORD()' was changed to improve security.  `OLD_PASSWORD()'
     returns the value of the old (pre-4.1) implementation of
     `PASSWORD()' as a binary string, and is intended to permit you to
     reset passwords for any pre-4.1 clients that need to connect to
     your version 5.1 MySQL server without locking them out. See *Note
     password-hashing::.

   *  `PASSWORD(STR)'

     Calculates and returns a password string from the plaintext
     password STR and returns a binary string, or `NULL' if the
     argument was `NULL'. This is the function that is used for
     encrypting MySQL passwords for storage in the `Password' column of
     the `user' grant table.

          mysql> SELECT PASSWORD('badpwd');
                  -> '*AAB3E285149C0135D51A520E1940DD3263DC008C'

     `PASSWORD()' encryption is one-way (not reversible).

     `PASSWORD()' does not perform password encryption in the same way
     that Unix passwords are encrypted. See `ENCRYPT()'.

     *Note*:

     The `PASSWORD()' function is used by the authentication system in
     MySQL Server; you should _not_ use it in your own applications.
     For that purpose, consider `MD5()' or `SHA1()' instead. Also see
     section 2 (Challenge-Response Authentication Mechanism (CRAM)),
     for more information about handling passwords and authentication
     securely in your applications.

   *  `SHA1(STR)', `SHA(STR)'

     Calculates an SHA-1 160-bit checksum for the string, as described
     in RFC 3174 (Secure Hash Algorithm). The value is returned as a
     binary string of 40 hex digits, or `NULL' if the argument was
     `NULL'. One of the possible uses for this function is as a hash
     key. You can also use it as a cryptographic function for storing
     passwords.  `SHA()' is synonymous with `SHA1()'.

          mysql> SELECT SHA1('abc');
                  -> 'a9993e364706816aba3e25717850c26c9cd0d89d'

     `SHA1()' can be considered a cryptographically more secure
     equivalent of `MD5()'. However, see the note regarding the MD5 and
     SHA-1 algorithms at the beginning this section.

   *  `UNCOMPRESS(STRING_TO_UNCOMPRESS)'

     Uncompresses a string compressed by the `COMPRESS()' function. If
     the argument is not a compressed value, the result is `NULL'. This
     function requires MySQL to have been compiled with a compression
     library such as `zlib'. Otherwise, the return value is always
     `NULL'.

          mysql> SELECT UNCOMPRESS(COMPRESS('any string'));
                  -> 'any string'
          mysql> SELECT UNCOMPRESS('any string');
                  -> NULL

   *  `UNCOMPRESSED_LENGTH(COMPRESSED_STRING)'

     Returns the length that the compressed string had before being
     compressed.

          mysql> SELECT UNCOMPRESSED_LENGTH(COMPRESS(REPEAT('a',30)));
                  -> 30


File: manual.info,  Node: information-functions,  Next: miscellaneous-functions,  Prev: encryption-functions,  Up: other-functions

11.11.3 Information Functions
-----------------------------

*Name*                        *Description*
`BENCHMARK()'                 Repeatedly execute an expression
`CHARSET()'(v4.1.0)           Return the character set of the argument
`COERCIBILITY()'(v4.1.1)      Return the collation coercibility value of
                              the string  argument
`COLLATION()'(v4.1.0)         Return the collation of the string argument
`CONNECTION_ID()'             Return the connection ID (thread ID)   for
                              the connection
`CURRENT_USER()',             Return the username and hostname
`CURRENT_USER'                combination
`DATABASE()'                  Return the default (current) database name
`FOUND_ROWS()'                For a SELECT with a LIMIT clause, the
                              number of rows that would be returned were
                              there no LIMIT clause
`LAST_INSERT_ID()'            Value of the AUTOINCREMENT column   for
                              the last INSERT
`ROW_COUNT()'(v5.0.1)         The number of rows  updated
`SCHEMA()'(v5.0.2)            A synonym for DATABASE()
`SESSION_USER()'              Synonym for USER()
`SYSTEM_USER()'               Synonym for USER()
`USER()'                      Return the current username and hostname
`VERSION()'                   Returns a string that indicates the MySQL
                              server version

   *  `BENCHMARK(COUNT,EXPR)'

     The `BENCHMARK()' function executes the expression EXPR repeatedly
     COUNT times. It may be used to time how quickly MySQL processes
     the expression. The result value is always `0'. The intended use
     is from within the `mysql' client, which reports query execution
     times:

          mysql> SELECT BENCHMARK(1000000,ENCODE('hello','goodbye'));
          +----------------------------------------------+
          | BENCHMARK(1000000,ENCODE('hello','goodbye')) |
          +----------------------------------------------+
          |                                            0 |
          +----------------------------------------------+
          1 row in set (4.74 sec)

     The time reported is elapsed time on the client end, not CPU time
     on the server end. It is advisable to execute `BENCHMARK()'
     several times, and to interpret the result with regard to how
     heavily loaded the server machine is.

     `BENCHMARK()' is intended for measuring the runtime performance of
     scalar expressions, which has some significant implications for
     the way that you use it and interpret the results:

        * Only scalar expressions can be used. Although the expression
          can be a subquery, it must return a single column and at most
          a single row. For example, `BENCHMARK(10, (SELECT * FROM t))'
          will fail if the table `t' has more than one column or more
          than one row.

        * Executing a `SELECT EXPR' statement N times differs from
          executing `SELECT BENCHMARK(N, EXPR)' in terms of the amount
          of overhead involved. The two have very different execution
          profiles and you should not expect them to take the same
          amount of time. The former involves the parser, optimizer,
          table locking, and runtime evaluation N times each. The
          latter involves only runtime evaluation N times, and all the
          other components just once. Memory structures already
          allocated are reused, and runtime optimizations such as local
          caching of results already evaluated for aggregate functions
          can alter the results. Use of `BENCHMARK()' thus measures
          performance of the runtime component by giving more weight to
          that component and removing the `noise' introduced by the
          network, parser, optimizer, and so forth.

   *  `CHARSET(STR)'

     Returns the character set of the string argument.

          mysql> SELECT CHARSET('abc');
                  -> 'latin1'
          mysql> SELECT CHARSET(CONVERT('abc' USING utf8));
                  -> 'utf8'
          mysql> SELECT CHARSET(USER());
                  -> 'utf8'

   *  `COERCIBILITY(STR)'

     Returns the collation coercibility value of the string argument.

          mysql> SELECT COERCIBILITY('abc' COLLATE latin1_swedish_ci);
                  -> 0
          mysql> SELECT COERCIBILITY(USER());
                  -> 3
          mysql> SELECT COERCIBILITY('abc');
                  -> 4

     The return values have the meanings shown in the following table.
     Lower values have higher precedence.

     *Coercibility**Meaning*  *Example*
     `0'        Explicit   Value with `COLLATE' clause
                collation  
     `1'        No         Concatenation of strings with different
                collation  collations
     `2'        Implicit   Column value, stored routine parameter or
                collation  local variable
     `3'        System     `USER()' return value
                constant   
     `4'        Coercible  Literal string
     `5'        Ignorable  `NULL' or an expression derived from `NULL'

   *  `COLLATION(STR)'

     Returns the collation of the string argument.

          mysql> SELECT COLLATION('abc');
                  -> 'latin1_swedish_ci'
          mysql> SELECT COLLATION(_utf8'abc');
                  -> 'utf8_general_ci'

   *  `CONNECTION_ID()'

     Returns the connection ID (thread ID) for the connection.  Every
     connection has an ID that is unique among the set of currently
     connected clients.

          mysql> SELECT CONNECTION_ID();
                  -> 23786

   *  `CURRENT_USER', `CURRENT_USER()'

     Returns the username and hostname combination for the MySQL
     account that the server used to authenticate the current client.
     This account determines your access privileges.  Within a stored
     routine that is defined with the `SQL SECURITY DEFINER'
     characteristic, `CURRENT_USER()' returns the creator of the
     routine. The return value is a string in the `utf8' character set.

     The value of `CURRENT_USER()' can differ from the value of
     `USER()'.

          mysql> SELECT USER();
                  -> 'davida@localhost'
          mysql> SELECT * FROM mysql.user;
          ERROR 1044: Access denied for user ''@'localhost' to
          database 'mysql'
          mysql> SELECT CURRENT_USER();
                  -> '@localhost'

     The example illustrates that although the client specified a
     username of `davida' (as indicated by the value of the `USER()'
     function), the server authenticated the client using an anonymous
     user account (as seen by the empty username part of the
     `CURRENT_USER()' value). One way this might occur is that there is
     no account listed in the grant tables for `davida'.

   *  `DATABASE()'

     Returns the default (current) database name as a string in the
     `utf8' character set. If there is no default database, `DATABASE()'
     returns `NULL'. Within a stored routine, the default database is
     the database that the routine is associated with, which is not
     necessarily the same as the database that is the default in the
     calling context.

          mysql> SELECT DATABASE();
                  -> 'test'

     If there is no default database, `DATABASE()' returns `NULL'.

   *  `FOUND_ROWS()'

     A `SELECT' statement may include a `LIMIT' clause to restrict the
     number of rows the server returns to the client. In some cases, it
     is desirable to know how many rows the statement would have
     returned without the `LIMIT', but without running the statement
     again. To obtain this row count, include a `SQL_CALC_FOUND_ROWS'
     option in the `SELECT' statement, and then invoke `FOUND_ROWS()'
     afterward:

          mysql> SELECT SQL_CALC_FOUND_ROWS * FROM TBL_NAME
              -> WHERE id > 100 LIMIT 10;
          mysql> SELECT FOUND_ROWS();

     The second `SELECT' returns a number indicating how many rows the
     first `SELECT' would have returned had it been written without the
     `LIMIT' clause.

     In the absence of the `SQL_CALC_FOUND_ROWS' option in the most
     recent successful `SELECT' statement, `FOUND_ROWS()' returns the
     number of rows in the result set returned by that statement.

     The row count available through `FOUND_ROWS()' is transient and
     not intended to be available past the statement following the
     `SELECT SQL_CALC_FOUND_ROWS' statement. If you need to refer to
     the value later, save it:

          mysql> SELECT SQL_CALC_FOUND_ROWS * FROM ... ;
          mysql> SET @rows = FOUND_ROWS();

     If you are using `SELECT SQL_CALC_FOUND_ROWS', MySQL must
     calculate how many rows are in the full result set. However, this
     is faster than running the query again without `LIMIT', because
     the result set need not be sent to the client.

     `SQL_CALC_FOUND_ROWS' and `FOUND_ROWS()' can be useful in
     situations when you want to restrict the number of rows that a
     query returns, but also determine the number of rows in the full
     result set without running the query again. An example is a Web
     script that presents a paged display containing links to the pages
     that show other sections of a search result. Using `FOUND_ROWS()'
     allows you to determine how many other pages are needed for the
     rest of the result.

     The use of `SQL_CALC_FOUND_ROWS' and `FOUND_ROWS()' is more complex
     for `UNION' statements than for simple `SELECT' statements, because
     `LIMIT' may occur at multiple places in a `UNION'. It may be
     applied to individual `SELECT' statements in the `UNION', or
     global to the `UNION' result as a whole.

     The intent of `SQL_CALC_FOUND_ROWS' for `UNION' is that it should
     return the row count that would be returned without a global
     `LIMIT'. The conditions for use of `SQL_CALC_FOUND_ROWS' with
     `UNION' are:

        * The `SQL_CALC_FOUND_ROWS' keyword must appear in the first
          `SELECT' of the `UNION'.

        * The value of `FOUND_ROWS()' is exact only if `UNION ALL' is
          used. If `UNION' without `ALL' is used, duplicate removal
          occurs and the value of `FOUND_ROWS()' is only approximate.

        * If no `LIMIT' is present in the `UNION',
          `SQL_CALC_FOUND_ROWS' is ignored and returns the number of
          rows in the temporary table that is created to process the
          `UNION'.

     Beyond the cases described here, the behavior of `FOUND_ROWS()' is
     undefined (for example, its value following a `SELECT' statement
     that fails with an error).

     *Important*:

     `FOUND_ROWS()' is not replicated reliably using statement-based
     replication.  Starting with MySQL 5.1.23, this function is
     automatically replicated using row-based replication.

   *  `LAST_INSERT_ID()', `LAST_INSERT_ID(EXPR)'

     For MySQL 5.1.12 and later, `LAST_INSERT_ID()' (no arguments)
     returns the _first_ automatically generated value _successfully_
     inserted for an `AUTO_INCREMENT' column as a result of the most
     recently executed `INSERT' statement.  The value of
     `LAST_INSERT_ID()' remains unchanged if no rows are successfully
     inserted.

     For example, after inserting a row that generates an
     `AUTO_INCREMENT' value, you can get the value like this:

          mysql> SELECT LAST_INSERT_ID();
                  -> 195

     In MySQL 5.1.11 and earlier, `LAST_INSERT_ID()' (no arguments)
     returns the _first_ automatically generated value if any rows were
     successfully inserted or updated. This means that the returned
     value could be a value that was not successfully inserted into the
     table. If no rows were successfully inserted, `LAST_INSERT_ID()'
     returns 0.

     The value of `LAST_INSERT_ID()' will be consistent across all
     versions if all rows in the `INSERT' or `UPDATE' statement were
     successful.

     The currently executing statement does not affect the value of
     `LAST_INSERT_ID()'. Suppose that you generate an `AUTO_INCREMENT'
     value with one statement, and then refer to `LAST_INSERT_ID()' in a
     multiple-row `INSERT' statement that inserts rows into a table
     with its own `AUTO_INCREMENT' column. The value of
     `LAST_INSERT_ID()' will remain stable in the second statement; its
     value for the second and later rows is not affected by the earlier
     row insertions.  (However, if you mix references to
     `LAST_INSERT_ID()' and `LAST_INSERT_ID(EXPR)', the effect is
     undefined.)

     If the previous statement returned an error, the value of
     `LAST_INSERT_ID()' is undefined. For transactional tables, if the
     statement is rolled back due to an error, the value of
     `LAST_INSERT_ID()' is left undefined. For manual `ROLLBACK', the
     value of `LAST_INSERT_ID()' is not restored to that before the
     transaction; it remains as it was at the point of the `ROLLBACK'.

     Within the body of a stored routine (procedure or function) or a
     trigger, the value of `LAST_INSERT_ID()' changes the same way as
     for statements executed outside the body of these kinds of
     objects. The effect of a stored routine or trigger upon the value
     of `LAST_INSERT_ID()' that is seen by following statements depends
     on the kind of routine:

        * If a stored procedure executes statements that change the
          value of `LAST_INSERT_ID()', the changed value will be seen
          by statements that follow the procedure call.

        * For stored functions and triggers that change the value, the
          value is restored when the function or trigger ends, so
          following statements will not see a changed value.

     The ID that was generated is maintained in the server on a
     _per-connection basis_. This means that the value returned by the
     function to a given client is the first `AUTO_INCREMENT' value
     generated for most recent statement affecting an `AUTO_INCREMENT'
     column _by that client_. This value cannot be affected by other
     clients, even if they generate `AUTO_INCREMENT' values of their
     own. This behavior ensures that each client can retrieve its own ID
     without concern for the activity of other clients, and without the
     need for locks or transactions.

     The value of `LAST_INSERT_ID()' is not changed if you set the
     `AUTO_INCREMENT' column of a row to a non-`magic' value (that is,
     a value that is not `NULL' and not `0').

     *Important*:

     If you insert multiple rows using a single `INSERT' statement,
     `LAST_INSERT_ID()' returns the value generated for the _first_
     inserted row _only_. The reason for this is to make it possible to
     reproduce easily the same `INSERT' statement against some other
     server.

     For example:

          mysql> USE test;
          Database changed
          mysql> CREATE TABLE t (
              ->   id INT AUTO_INCREMENT NOT NULL PRIMARY KEY,
              ->   name VARCHAR(10) NOT NULL
              -> );
          Query OK, 0 rows affected (0.09 sec)

          mysql> INSERT INTO t VALUES (NULL, 'Bob');
          Query OK, 1 row affected (0.01 sec)

          mysql> SELECT * FROM t;
          +----+------+
          | id | name |
          +----+------+
          |  1 | Bob  |
          +----+------+
          1 row in set (0.01 sec)

          mysql> SELECT LAST_INSERT_ID();
          +------------------+
          | LAST_INSERT_ID() |
          +------------------+
          |                1 |
          +------------------+
          1 row in set (0.00 sec)

          mysql> INSERT INTO t VALUES
              -> (NULL, 'Mary'), (NULL, 'Jane'), (NULL, 'Lisa');
          Query OK, 3 rows affected (0.00 sec)
          Records: 3  Duplicates: 0  Warnings: 0

          mysql> SELECT * FROM t;
          +----+------+
          | id | name |
          +----+------+
          |  1 | Bob  |
          |  2 | Mary |
          |  3 | Jane |
          |  4 | Lisa |
          +----+------+
          4 rows in set (0.01 sec)

          mysql> SELECT LAST_INSERT_ID();
          +------------------+
          | LAST_INSERT_ID() |
          +------------------+
          |                2 |
          +------------------+
          1 row in set (0.00 sec)

     Although the second `INSERT' statement inserted three new rows
     into `t', the ID generated for the first of these rows was `2',
     and it is this value that is returned by `LAST_INSERT_ID()' for the
     following `SELECT' statement.

     If you use `INSERT IGNORE' and the row is ignored, the
     `AUTO_INCREMENT' counter is not incremented and `LAST_INSERT_ID()'
     returns `0', which reflects that no row was inserted.

     If EXPR is given as an argument to `LAST_INSERT_ID()', the value
     of the argument is returned by the function and is remembered as
     the next value to be returned by `LAST_INSERT_ID()'. This can be
     used to simulate sequences:

       1. Create a table to hold the sequence counter and initialize it:

               mysql> CREATE TABLE sequence (id INT NOT NULL);
               mysql> INSERT INTO sequence VALUES (0);

       2. Use the table to generate sequence numbers like this:

               mysql> UPDATE sequence SET id=LAST_INSERT_ID(id+1);
               mysql> SELECT LAST_INSERT_ID();

          The `UPDATE' statement increments the sequence counter and
          causes the next call to `LAST_INSERT_ID()' to return the
          updated value. The `SELECT' statement retrieves that value.
          The *Note `mysql_insert_id()': mysql-insert-id. C API
          function can also be used to get the value. See *Note
          mysql-insert-id::.

     You can generate sequences without calling `LAST_INSERT_ID()', but
     the utility of using the function this way is that the ID value is
     maintained in the server as the last automatically generated
     value. It is multi-user safe because multiple clients can issue
     the `UPDATE' statement and get their own sequence value with the
     `SELECT' statement (or *Note `mysql_insert_id()':
     mysql-insert-id.), without affecting or being affected by other
     clients that generate their own sequence values.

     Note that *Note `mysql_insert_id()': mysql-insert-id.  is only
     updated after `INSERT' and `UPDATE' statements, so you cannot use
     the C API function to retrieve the value for `LAST_INSERT_ID(EXPR)'
     after executing other SQL statements like `SELECT' or `SET'.

   *  `ROW_COUNT()'

     `ROW_COUNT()' returns the number of rows updated, inserted, or
     deleted by the preceding statement. This is the same as the row
     count that the `mysql' client displays and the value from the
     *Note `mysql_affected_rows()': mysql-affected-rows. C API function.

          mysql> INSERT INTO t VALUES(1),(2),(3);
          Query OK, 3 rows affected (0.00 sec)
          Records: 3  Duplicates: 0  Warnings: 0

          mysql> SELECT ROW_COUNT();
          +-------------+
          | ROW_COUNT() |
          +-------------+
          |           3 |
          +-------------+
          1 row in set (0.00 sec)

          mysql> DELETE FROM t WHERE i IN(1,2);
          Query OK, 2 rows affected (0.00 sec)

          mysql> SELECT ROW_COUNT();
          +-------------+
          | ROW_COUNT() |
          +-------------+
          |           2 |
          +-------------+
          1 row in set (0.00 sec)

     *Important*:

     `ROW_COUNT()' is not replicated reliably using statement-based
     replication.  Beginning with MySQL 5.1.23, this function is
     automatically replicated using row-based replication. (Bug#30244
     (http://bugs.mysql.com/30244))

   *  `SCHEMA()'

     This function is a synonym for `DATABASE()'.

   *  `SESSION_USER()'

     `SESSION_USER()' is a synonym for `USER()'.

   *  `SYSTEM_USER()'

     `SYSTEM_USER()' is a synonym for `USER()'.

   *  `USER()'

     Returns the current MySQL username and hostname as a string in the
     `utf8' character set.

          mysql> SELECT USER();
                  -> 'davida@localhost'

     The value indicates the username you specified when connecting to
     the server, and the client host from which you connected. The
     value can be different from that of `CURRENT_USER()'.

     You can extract only the username part like this:

          mysql> SELECT SUBSTRING_INDEX(USER(),'@',1);
                  -> 'davida'

   *  `VERSION()'

     Returns a string that indicates the MySQL server version.  The
     string uses the `utf8' character set.

          mysql> SELECT VERSION();
                  -> '5.1.28-standard'

     Note that if your version string ends with `-log' this means that
     logging is enabled.


File: manual.info,  Node: miscellaneous-functions,  Prev: information-functions,  Up: other-functions

11.11.4 Miscellaneous Functions
-------------------------------

*Name*                        *Description*
`DEFAULT()'                   Return the default value for a table column
`GET_LOCK()'                  Get a named lock
`INET_ATON()'                 Return the numeric value of an IP address
`INET_NTOA()'                 Return the IP address from a numeric value
`IS_FREE_LOCK()'              Checks whether the named lock  is free
`IS_USED_LOCK()'(v4.1.0)      Checks whether the named lock is in use.
                              Return connection identifier if true.
`MASTER_POS_WAIT()'           Block until the slave has read and
                              applied all updates up to the specified
                              position
`NAME_CONST()'(v5.0.12)       Causes the column to have the given name
`RAND()'                      Return a random floating-point value
`RELEASE_LOCK()'              Releases the named lock
`SLEEP()'(v5.0.12)            Sleep for a number of seconds
`UUID_SHORT()'(v5.1.20)       Return an integer-valued universal
                              identifier
`UUID()'(v4.1.2)              Return a Universal Unique Identifier (UUID)
`VALUES()'(v4.1.1)            Defines the values to be used during an
                              INSERT

   *  `DEFAULT(COL_NAME)'

     Returns the default value for a table column. An error results if
     the column has no default value.

          mysql> UPDATE t SET i = DEFAULT(i)+1 WHERE id < 100;

   * `FORMAT(X,D)'

     Formats the number X to a format like `'#,###,###.##'', rounded to
     D decimal places, and returns the result as a string. For details,
     see *Note string-functions::.

   *  `GET_LOCK(STR,TIMEOUT)'

     Tries to obtain a lock with a name given by the string STR, using
     a timeout of TIMEOUT seconds. Returns `1' if the lock was obtained
     successfully, `0' if the attempt timed out (for example, because
     another client has previously locked the name), or `NULL' if an
     error occurred (such as running out of memory or the thread was
     killed with `mysqladmin kill'). If you have a lock obtained with
     `GET_LOCK()', it is released when you execute `RELEASE_LOCK()',
     execute a new `GET_LOCK()', or your connection terminates (either
     normally or abnormally). Locks obtained with `GET_LOCK()' do not
     interact with transactions. That is, committing a transaction does
     not release any such locks obtained during the transaction.

     This function can be used to implement application locks or to
     simulate record locks. Names are locked on a server-wide basis. If
     a name has been locked by one client, `GET_LOCK()' blocks any
     request by another client for a lock with the same name.  This
     allows clients that agree on a given lock name to use the name to
     perform cooperative advisory locking. But be aware that it also
     allows a client that is not among the set of cooperating clients
     to lock a name, either inadvertently or deliberately, and thus
     prevent any of the cooperating clients from locking that name. One
     way to reduce the likelihood of this is to use lock names that are
     database-specific or application-specific. For example, use lock
     names of the form DB_NAME.STR or APP_NAME.STR.

          mysql> SELECT GET_LOCK('lock1',10);
                  -> 1
          mysql> SELECT IS_FREE_LOCK('lock2');
                  -> 1
          mysql> SELECT GET_LOCK('lock2',10);
                  -> 1
          mysql> SELECT RELEASE_LOCK('lock2');
                  -> 1
          mysql> SELECT RELEASE_LOCK('lock1');
                  -> NULL

     The second `RELEASE_LOCK()' call returns `NULL' because the lock
     `'lock1'' was automatically released by the second `GET_LOCK()'
     call.

     *Note*:

     If a client attempts to acquire a lock that is already held by
     another client, it blocks according to the TIMEOUT argument. If the
     blocked client terminates, its thread does not die until the lock
     request times out. This is a known bug (fixed in MySQL 6.0).

   *  `INET_ATON(EXPR)'

     Given the dotted-quad representation of a network address as a
     string, returns an integer that represents the numeric value of
     the address. Addresses may be 4- or 8-byte addresses.

          mysql> SELECT INET_ATON('209.207.224.40');
                  -> 3520061480

     The generated number is always in network byte order. For the
     example just shown, the number is calculated as 209x256^3 +
     207x256^2 + 224x256 + 40.

     `INET_ATON()' also understands short-form IP addresses:

          mysql> SELECT INET_ATON('127.0.0.1'), INET_ATON('127.1');
                  -> 2130706433, 2130706433

     *Note*:

     When storing values generated by `INET_ATON()', it is recommended
     that you use an `INT UNSIGNED' column. If you use a (signed) `INT'
     column, values corresponding to IP addresses for which the first
     octet is greater than 127 cannot be stored correctly. See *Note
     numeric-types::.

   *  `INET_NTOA(EXPR)'

     Given a numeric network address (4 or 8 byte), returns the
     dotted-quad representation of the address as a string.

          mysql> SELECT INET_NTOA(3520061480);
                  -> '209.207.224.40'

   *  `IS_FREE_LOCK(STR)'

     Checks whether the lock named STR is free to use (that is, not
     locked). Returns `1' if the lock is free (no one is using the
     lock), `0' if the lock is in use, and `NULL' if an error occurs
     (such as an incorrect argument).

   *  `IS_USED_LOCK(STR)'

     Checks whether the lock named STR is in use (that is, locked). If
     so, it returns the connection identifier of the client that holds
     the lock.  Otherwise, it returns `NULL'.

   *  `MASTER_POS_WAIT(LOG_NAME,LOG_POS[,TIMEOUT])'

     This function is useful for control of master/slave
     synchronization. It blocks until the slave has read and applied
     all updates up to the specified position in the master log. The
     return value is the number of log events the slave had to wait for
     to advance to the specified position.  The function returns `NULL'
     if the slave SQL thread is not started, the slave's master
     information is not initialized, the arguments are incorrect, or an
     error occurs. It returns `-1' if the timeout has been exceeded. If
     the slave SQL thread stops while `MASTER_POS_WAIT()' is waiting,
     the function returns `NULL'. If the slave is past the specified
     position, the function returns immediately.

     If a TIMEOUT value is specified, `MASTER_POS_WAIT()' stops waiting
     when TIMEOUT seconds have elapsed. TIMEOUT must be greater than 0;
     a zero or negative TIMEOUT means no timeout.

   *  `NAME_CONST(NAME,VALUE)'

     Returns the given value. When used to produce a result set column,
     `NAME_CONST()' causes the column to have the given name. The
     arguments should be constants.

          mysql> SELECT NAME_CONST('myname', 14);
          +--------+
          | myname |
          +--------+
          |     14 |
          +--------+

     This function was added in MySQL 5.0.12. It is for internal use
     only. The server uses it when writing statements from stored
     routines that contain references to local routine variables, as
     described in *Note stored-procedure-logging::, You might see this
     function in the output from `mysqlbinlog'.

   *  `RELEASE_LOCK(STR)'

     Releases the lock named by the string STR that was obtained with
     `GET_LOCK()'. Returns `1' if the lock was released, `0' if the
     lock was not established by this thread (in which case the lock is
     not released), and `NULL' if the named lock did not exist. The
     lock does not exist if it was never obtained by a call to
     `GET_LOCK()' or if it has previously been released.

     The `DO' statement is convenient to use with `RELEASE_LOCK()'. See
     *Note do::.

   *  `SLEEP(DURATION)'

     Sleeps (pauses) for the number of seconds given by the DURATION
     argument, then returns 0. If `SLEEP()' is interrupted, it returns
     1. The duration may have a fractional part given in microseconds.

   *  `UUID()'

     Returns a Universal Unique Identifier (UUID) generated according
     to `DCE 1.1: Remote Procedure Call' (Appendix A) CAE (Common
     Applications Environment) Specifications published by The Open
     Group in October 1997 (Document Number C706,
     `http://www.opengroup.org/public/pubs/catalog/c706.htm').

     A UUID is designed as a number that is globally unique in space
     and time. Two calls to `UUID()' are expected to generate two
     different values, even if these calls are performed on two
     separate computers that are not connected to each other.

     A UUID is a 128-bit number represented by a `utf8' string of five
     hexadecimal numbers in `aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee'
     format:

        * The first three numbers are generated from a timestamp.

        * The fourth number preserves temporal uniqueness in case the
          timestamp value loses monotonicity (for example, due to
          daylight saving time).

        * The fifth number is an IEEE 802 node number that provides
          spatial uniqueness. A random number is substituted if the
          latter is not available (for example, because the host
          computer has no Ethernet card, or we do not know how to find
          the hardware address of an interface on your operating
          system). In this case, spatial uniqueness cannot be
          guaranteed. Nevertheless, a collision should have _very_ low
          probability.

          Currently, the MAC address of an interface is taken into
          account only on FreeBSD and Linux. On other operating
          systems, MySQL uses a randomly generated 48-bit number.

          mysql> SELECT UUID();
                  -> '6ccd780c-baba-1026-9564-0040f4311e29'

     *Warning*:

     The `UUID()' function returns a string using the character set
     defined by the `character_set_server' parameter. If you are using
     UUID values in your tables and these columns are indexed the
     character set of your column or table should match the character
     set used when the `UUID()' was called. If you do not use the same
     character set for the column and the UUID value, then the indexes
     on those columns will not be used, which may lead to a reduction
     in performance and locked tables during operations as the table is
     searched sequentially for the value.

     You can convert between different character sets when using
     UUID-based strings using the `CONVERT()' function.

     *Note*:

     `UUID()' does not work with statement-based replication.

   *  `UUID_SHORT()'

     Returns a `short' universal identifier as a 64-bit unsigned
     integer (rather than a string-form 128-bit identifier as returned
     by the `UUID()' function).

     The value of `UUID_SHORT()' is guaranteed to be unique if the
     following conditions hold:

        * The `server_id' of the current host is unique among your set
          of master and slave servers

        * `server_id' is between 0 and 255

        * You don't set back your system time for your server between
          `mysqld' restarts

        * You do not invoke `UUID_SHORT()' on average more than 16
          million times per second between `mysqld' restarts

     The `UUID_SHORT()' return value is constructed this way:

            (server_id & 255) << 56
          + (server_startup_time_in_seconds << 24)
          + incremented_variable++;

          mysql> SELECT UUID_SHORT();
                  -> 92395783831158784

     Note that `UUID_SHORT()' does not work with statement-based
     replication.

     This function was added in MySQL 5.1.20.

   *  `VALUES(COL_NAME)'

     In an `INSERT ... ON DUPLICATE KEY UPDATE' statement, you can use
     the `VALUES(COL_NAME)' function in the `UPDATE' clause to refer to
     column values from the `INSERT' portion of the statement. In other
     words, `VALUES(COL_NAME)' in the `UPDATE' clause refers to the
     value of COL_NAME that would be inserted, had no duplicate-key
     conflict occurred. This function is especially useful in
     multiple-row inserts. The `VALUES()' function is meaningful only
     in `INSERT ... ON DUPLICATE KEY UPDATE' statements and returns
     `NULL' otherwise.  *Note insert-on-duplicate::.

          mysql> INSERT INTO table (a,b,c) VALUES (1,2,3),(4,5,6)
              -> ON DUPLICATE KEY UPDATE c=VALUES(a)+VALUES(b);


File: manual.info,  Node: group-by-functions-and-modifiers,  Prev: other-functions,  Up: functions

11.12 Functions and Modifiers for Use with `GROUP BY' Clauses
=============================================================

* Menu:

* group-by-functions::           `GROUP BY' (Aggregate) Functions
* group-by-modifiers::           `GROUP BY' Modifiers
* group-by-hidden-fields::       `GROUP BY' and `HAVING' with Hidden Fields


File: manual.info,  Node: group-by-functions,  Next: group-by-modifiers,  Prev: group-by-functions-and-modifiers,  Up: group-by-functions-and-modifiers

11.12.1 `GROUP BY' (Aggregate) Functions
----------------------------------------

*Name*                        *Description*
`AVG()'                       Return the average value of the argument
`BIT_AND()'                   Return bitwise and
`BIT_OR()'                    Return bitwise or
`BIT_XOR()'(v4.1.1)           Return bitwise xor
`COUNT(DISTINCT)'             Return the count of a number of different
                              values
`COUNT()'                     Return a count of the number of rows
                              returned
`GROUP_CONCAT()'(v4.1)        Return a concatenated string
`MAX()'                       Return the maximum value
`MIN()'                       Return the minimum value
`STD()'                       Return the population standard deviation
`STDDEV_POP()'(v5.0.3)        Return the population standard deviation
`STDDEV_SAMP()'(v5.0.3)       Return the sample standard deviation
`STDDEV()'                    Return the population standard deviation
`SUM()'                       Return the sum
`VAR_POP()'(v5.0.3)           Return the population standard variance
`VAR_SAMP()'(v5.0.3)          Return the sample variance
`VARIANCE()'(v4.1)            Return the population standard variance

This section describes group (aggregate) functions that operate on sets
of values. Unless otherwise stated, group functions ignore `NULL'
values.

If you use a group function in a statement containing no `GROUP BY'
clause, it is equivalent to grouping on all rows.

For numeric arguments, the variance and standard deviation functions
return a `DOUBLE' value. The `SUM()' and `AVG()' functions return a
`DECIMAL' value for exact-value arguments (integer or `DECIMAL'), and a
`DOUBLE' value for approximate-value arguments (`FLOAT' or `DOUBLE').

The `SUM()' and `AVG()' aggregate functions do not work with temporal
values. (They convert the values to numbers, losing everything after
the first non-numeric character.) To work around this problem, you can
convert to numeric units, perform the aggregate operation, and convert
back to a temporal value. Examples:

     SELECT SEC_TO_TIME(SUM(TIME_TO_SEC(TIME_COL))) FROM TBL_NAME;
     SELECT FROM_DAYS(SUM(TO_DAYS(DATE_COL))) FROM TBL_NAME;

Functions such as `SUM()' or `AVG()' that expect a numeric argument
cast the argument to a number if necessary. For `SET' or `ENUM' values,
the cast operation causes the underlying numeric value to be used.

   *  `AVG([DISTINCT] EXPR)'

     Returns the average value of `EXPR'. The `DISTINCT' option can be
     used to return the average of the distinct values of EXPR.

     `AVG()' returns `NULL' if there were no matching rows.

          mysql> SELECT student_name, AVG(test_score)
              ->        FROM student
              ->        GROUP BY student_name;

   *  `BIT_AND(EXPR)'

     Returns the bitwise `AND' of all bits in EXPR. The calculation is
     performed with 64-bit (`BIGINT') precision.

     This function returns `18446744073709551615' if there were no
     matching rows. (This is the value of an unsigned `BIGINT' value
     with all bits set to 1.)

   *  `BIT_OR(EXPR)'

     Returns the bitwise `OR' of all bits in EXPR. The calculation is
     performed with 64-bit (`BIGINT') precision.

     This function returns `0' if there were no matching rows.

   *  `BIT_XOR(EXPR)'

     Returns the bitwise `XOR' of all bits in EXPR. The calculation is
     performed with 64-bit (`BIGINT') precision.

     This function returns `0' if there were no matching rows.

   *  `COUNT(EXPR)'

     Returns a count of the number of non-`NULL' values of EXPR in the
     rows retrieved by a `SELECT' statement. The result is a `BIGINT'
     value.

     `COUNT()' returns `0' if there were no matching rows.

          mysql> SELECT student.student_name,COUNT(*)
              ->        FROM student,course
              ->        WHERE student.student_id=course.student_id
              ->        GROUP BY student_name;

     `COUNT(*)' is somewhat different in that it returns a count of the
     number of rows retrieved, whether or not they contain `NULL'
     values.

     `COUNT(*)' is optimized to return very quickly if the `SELECT'
     retrieves from one table, no other columns are retrieved, and
     there is no `WHERE' clause. For example:

          mysql> SELECT COUNT(*) FROM student;

     This optimization applies only to `MyISAM' tables only, because an
     exact row count is stored for this storage engine and can be
     accessed very quickly. For transactional storage engines such as
     `InnoDB', storing an exact row count is more problematic because
     multiple transactions may be occurring, each of which may affect
     the count.

   *  `COUNT(DISTINCT EXPR,[EXPR...])'

     Returns a count of the number of different non-`NULL' values.

     `COUNT(DISTINCT)' returns `0' if there were no matching rows.

          mysql> SELECT COUNT(DISTINCT results) FROM student;

     In MySQL, you can obtain the number of distinct expression
     combinations that do not contain `NULL' by giving a list of
     expressions. In standard SQL, you would have to do a concatenation
     of all expressions inside `COUNT(DISTINCT ...)'.

   *  `GROUP_CONCAT(EXPR)'

     This function returns a string result with the concatenated
     non-`NULL' values from a group. It returns `NULL' if there are no
     non-`NULL' values. The full syntax is as follows:

          GROUP_CONCAT([DISTINCT] EXPR [,EXPR ...]
                       [ORDER BY {UNSIGNED_INTEGER | COL_NAME | EXPR}
                           [ASC | DESC] [,COL_NAME ...]]
                       [SEPARATOR STR_VAL])

          mysql> SELECT student_name,
              ->     GROUP_CONCAT(test_score)
              ->     FROM student
              ->     GROUP BY student_name;

     Or:

          mysql> SELECT student_name,
              ->     GROUP_CONCAT(DISTINCT test_score
              ->               ORDER BY test_score DESC SEPARATOR ' ')
              ->     FROM student
              ->     GROUP BY student_name;

     In MySQL, you can get the concatenated values of expression
     combinations. You can eliminate duplicate values by using
     `DISTINCT'. If you want to sort values in the result, you should
     use `ORDER BY' clause. To sort in reverse order, add the `DESC'
     (descending) keyword to the name of the column you are sorting by
     in the `ORDER BY' clause. The default is ascending order; this may
     be specified explicitly using the `ASC' keyword. `SEPARATOR' is
     followed by the string value that should be inserted between
     values of result. The default is a comma (``,''). You can
     eliminate the separator altogether by specifying `SEPARATOR '''.

     The result is truncated to the maximum length that is given by the
     `group_concat_max_len' system variable, which has a default value
     of 1024. The value can be set higher, although the effective
     maximum length of the return value is constrained by the value of
     `max_allowed_packet'. The syntax to change the value of
     `group_concat_max_len' at runtime is as follows, where VAL is an
     unsigned integer:

          SET [SESSION | GLOBAL] group_concat_max_len = VAL;

     The type returned by `GROUP_CONCAT()' is always `VARCHAR' unless
     `group_concat_max_len' is greater than 512, in which case, it
     returns a `BLOB'.

     See also `CONCAT()' and `CONCAT_WS()': *Note string-functions::.

   *  `MAX([DISTINCT] EXPR)'

     Returns the maximum value of EXPR.  `MAX()' may take a string
     argument; in such cases, it returns the maximum string value. See
     *Note mysql-indexes::. The `DISTINCT' keyword can be used to find
     the maximum of the distinct values of EXPR, however, this produces
     the same result as omitting `DISTINCT'.

     `MAX()' returns `NULL' if there were no matching rows.

          mysql> SELECT student_name, MIN(test_score), MAX(test_score)
              ->        FROM student
              ->        GROUP BY student_name;

     For `MAX()', MySQL currently compares `ENUM' and `SET' columns by
     their string value rather than by the string's relative position
     in the set. This differs from how `ORDER BY' compares them. This
     is expected to be rectified in a future MySQL release.

   *  `MIN([DISTINCT] EXPR)'

     Returns the minimum value of EXPR.  `MIN()' may take a string
     argument; in such cases, it returns the minimum string value. See
     *Note mysql-indexes::. The `DISTINCT' keyword can be used to find
     the minimum of the distinct values of EXPR, however, this produces
     the same result as omitting `DISTINCT'.

     `MIN()' returns `NULL' if there were no matching rows.

          mysql> SELECT student_name, MIN(test_score), MAX(test_score)
              ->        FROM student
              ->        GROUP BY student_name;

     For `MIN()', MySQL currently compares `ENUM' and `SET' columns by
     their string value rather than by the string's relative position
     in the set. This differs from how `ORDER BY' compares them. This
     is expected to be rectified in a future MySQL release.

   *  `STD(EXPR)'

     Returns the population standard deviation of EXPR. This is an
     extension to standard SQL. The standard SQL function
     `STDDEV_POP()' can be used instead.

     This function returns `NULL' if there were no matching rows.

   *  `STDDEV(EXPR)'

     Returns the population standard deviation of EXPR. This function
     is provided for compatibility with Oracle. The standard SQL
     function `STDDEV_POP()' can be used instead.

     This function returns `NULL' if there were no matching rows.

   *  `STDDEV_POP(EXPR)'

     Returns the population standard deviation of EXPR (the square root
     of `VAR_POP()'). You can also use `STD()' or `STDDEV()', which are
     equivalent but not standard SQL.

     `STDDEV_POP()' returns `NULL' if there were no matching rows.

   *  `STDDEV_SAMP(EXPR)'

     Returns the sample standard deviation of EXPR (the square root of
     `VAR_SAMP()'.

     `STDDEV_SAMP()' returns `NULL' if there were no matching rows.

   *  `SUM([DISTINCT] EXPR)'

     Returns the sum of EXPR. If the return set has no rows, `SUM()'
     returns `NULL'. The `DISTINCT' keyword can be used in MySQL 5.1 to
     sum only the distinct values of EXPR.

     `SUM()' returns `NULL' if there were no matching rows.

   *  `VAR_POP(EXPR)'

     Returns the population standard variance of EXPR. It considers
     rows as the whole population, not as a sample, so it has the
     number of rows as the denominator. You can also use `VARIANCE()',
     which is equivalent but is not standard SQL.

     `VAR_POP()' returns `NULL' if there were no matching rows.

   *  `VAR_SAMP(EXPR)'

     Returns the sample variance of EXPR. That is, the denominator is
     the number of rows minus one.

     `VAR_SAMP()' returns `NULL' if there were no matching rows.

   *  `VARIANCE(EXPR)'

     Returns the population standard variance of EXPR. This is an
     extension to standard SQL. The standard SQL function `VAR_POP()'
     can be used instead.

     `VARIANCE()' returns `NULL' if there were no matching rows.


File: manual.info,  Node: group-by-modifiers,  Next: group-by-hidden-fields,  Prev: group-by-functions,  Up: group-by-functions-and-modifiers

11.12.2 `GROUP BY' Modifiers
----------------------------

The `GROUP BY' clause allows a `WITH ROLLUP' modifier that causes extra
rows to be added to the summary output. These rows represent
higher-level (or super-aggregate) summary operations. `ROLLUP' thus
allows you to answer questions at multiple levels of analysis with a
single query. It can be used, for example, to provide support for OLAP
(Online Analytical Processing) operations.

Suppose that a table named `sales' has `year', `country', `product',
and `profit' columns for recording sales profitability:

     CREATE TABLE sales
     (
         year    INT NOT NULL,
         country VARCHAR(20) NOT NULL,
         product VARCHAR(32) NOT NULL,
         profit  INT
     );

The table's contents can be summarized per year with a simple `GROUP
BY' like this:

     mysql> SELECT year, SUM(profit) FROM sales GROUP BY year;
     +------+-------------+
     | year | SUM(profit) |
     +------+-------------+
     | 2000 |        4525 |
     | 2001 |        3010 |
     +------+-------------+

This output shows the total profit for each year, but if you also want
to determine the total profit summed over all years, you must add up
the individual values yourself or run an additional query.

Or you can use `ROLLUP', which provides both levels of analysis with a
single query. Adding a `WITH ROLLUP' modifier to the `GROUP BY' clause
causes the query to produce another row that shows the grand total over
all year values:

     mysql> SELECT year, SUM(profit) FROM sales GROUP BY year WITH ROLLUP;
     +------+-------------+
     | year | SUM(profit) |
     +------+-------------+
     | 2000 |        4525 |
     | 2001 |        3010 |
     | NULL |        7535 |
     +------+-------------+

The grand total super-aggregate line is identified by the value `NULL'
in the `year' column.

`ROLLUP' has a more complex effect when there are multiple `GROUP BY'
columns. In this case, each time there is a `break' (change in value) in
any but the last grouping column, the query produces an extra
super-aggregate summary row.

For example, without `ROLLUP', a summary on the `sales' table based on
`year', `country', and `product' might look like this:

     mysql> SELECT year, country, product, SUM(profit)
         -> FROM sales
         -> GROUP BY year, country, product;
     +------+---------+------------+-------------+
     | year | country | product    | SUM(profit) |
     +------+---------+------------+-------------+
     | 2000 | Finland | Computer   |        1500 |
     | 2000 | Finland | Phone      |         100 |
     | 2000 | India   | Calculator |         150 |
     | 2000 | India   | Computer   |        1200 |
     | 2000 | USA     | Calculator |          75 |
     | 2000 | USA     | Computer   |        1500 |
     | 2001 | Finland | Phone      |          10 |
     | 2001 | USA     | Calculator |          50 |
     | 2001 | USA     | Computer   |        2700 |
     | 2001 | USA     | TV         |         250 |
     +------+---------+------------+-------------+

The output indicates summary values only at the year/country/product
level of analysis. When `ROLLUP' is added, the query produces several
extra rows:

     mysql> SELECT year, country, product, SUM(profit)
         -> FROM sales
         -> GROUP BY year, country, product WITH ROLLUP;
     +------+---------+------------+-------------+
     | year | country | product    | SUM(profit) |
     +------+---------+------------+-------------+
     | 2000 | Finland | Computer   |        1500 |
     | 2000 | Finland | Phone      |         100 |
     | 2000 | Finland | NULL       |        1600 |
     | 2000 | India   | Calculator |         150 |
     | 2000 | India   | Computer   |        1200 |
     | 2000 | India   | NULL       |        1350 |
     | 2000 | USA     | Calculator |          75 |
     | 2000 | USA     | Computer   |        1500 |
     | 2000 | USA     | NULL       |        1575 |
     | 2000 | NULL    | NULL       |        4525 |
     | 2001 | Finland | Phone      |          10 |
     | 2001 | Finland | NULL       |          10 |
     | 2001 | USA     | Calculator |          50 |
     | 2001 | USA     | Computer   |        2700 |
     | 2001 | USA     | TV         |         250 |
     | 2001 | USA     | NULL       |        3000 |
     | 2001 | NULL    | NULL       |        3010 |
     | NULL | NULL    | NULL       |        7535 |
     +------+---------+------------+-------------+

For this query, adding `ROLLUP' causes the output to include summary
information at four levels of analysis, not just one. Here's how to
interpret the `ROLLUP' output:

   * Following each set of product rows for a given year and country,
     an extra summary row is produced showing the total for all
     products. These rows have the `product' column set to `NULL'.

   * Following each set of rows for a given year, an extra summary row
     is produced showing the total for all countries and products.
     These rows have the `country' and `products' columns set to `NULL'.

   * Finally, following all other rows, an extra summary row is
     produced showing the grand total for all years, countries, and
     products. This row has the `year', `country', and `products'
     columns set to `NULL'.

*Other Considerations When using `ROLLUP'*

The following items list some behaviors specific to the MySQL
implementation of `ROLLUP':

When you use `ROLLUP', you cannot also use an `ORDER BY' clause to sort
the results. In other words, `ROLLUP' and `ORDER BY' are mutually
exclusive. However, you still have some control over sort order. `GROUP
BY' in MySQL sorts results, and you can use explicit `ASC' and `DESC'
keywords with columns named in the `GROUP BY' list to specify sort
order for individual columns. (The higher-level summary rows added by
`ROLLUP' still appear after the rows from which they are calculated,
regardless of the sort order.)

`LIMIT' can be used to restrict the number of rows returned to the
client. `LIMIT' is applied after `ROLLUP', so the limit applies against
the extra rows added by `ROLLUP'. For example:

     mysql> SELECT year, country, product, SUM(profit)
         -> FROM sales
         -> GROUP BY year, country, product WITH ROLLUP
         -> LIMIT 5;
     +------+---------+------------+-------------+
     | year | country | product    | SUM(profit) |
     +------+---------+------------+-------------+
     | 2000 | Finland | Computer   |        1500 |
     | 2000 | Finland | Phone      |         100 |
     | 2000 | Finland | NULL       |        1600 |
     | 2000 | India   | Calculator |         150 |
     | 2000 | India   | Computer   |        1200 |
     +------+---------+------------+-------------+

Using `LIMIT' with `ROLLUP' may produce results that are more difficult
to interpret, because you have less context for understanding the
super-aggregate rows.

The `NULL' indicators in each super-aggregate row are produced when the
row is sent to the client. The server looks at the columns named in the
`GROUP BY' clause following the leftmost one that has changed value. For
any column in the result set with a name that is a lexical match to any
of those names, its value is set to `NULL'. (If you specify grouping
columns by column number, the server identifies which columns to set to
`NULL' by number.)

Because the `NULL' values in the super-aggregate rows are placed into
the result set at such a late stage in query processing, you cannot
test them as `NULL' values within the query itself. For example, you
cannot add `HAVING product IS NULL' to the query to eliminate from the
output all but the super-aggregate rows.

On the other hand, the `NULL' values do appear as `NULL' on the client
side and can be tested as such using any MySQL client programming
interface.


File: manual.info,  Node: group-by-hidden-fields,  Prev: group-by-modifiers,  Up: group-by-functions-and-modifiers

11.12.3 `GROUP BY' and `HAVING' with Hidden Fields
--------------------------------------------------

MySQL extends the use of `GROUP BY' so that you can use non-aggregated
columns or calculations in the `SELECT' list that do not appear in the
`GROUP BY' clause. You can use this feature to get better performance
by avoiding unnecessary column sorting and grouping. For example, you
do not need to group on `customer.name' in the following query:

     SELECT order.custid, customer.name, MAX(payments)
       FROM order,customer
       WHERE order.custid = customer.custid
       GROUP BY order.custid;

In standard SQL, you would have to add `customer.name' to the `GROUP
BY' clause. In MySQL, the name is redundant.

Do _not_ use this feature if the columns you omit from the `GROUP BY'
part are not constant in the group. The server is free to return any
value from the group, so the results are indeterminate unless all
values are the same.

A similar MySQL extension applies to the `HAVING' clause. The SQL
standard does not allow the `HAVING' clause to name any column that is
not found in the `GROUP BY' clause if it is not enclosed in an
aggregate function. MySQL allows the use of such columns to simplify
calculations. This extension assumes that the non-grouped columns will
have the same group-wise values. Otherwise, the result is indeterminate.

If the `ONLY_FULL_GROUP_BY' SQL mode is enabled, the MySQL extension to
`GROUP BY' does not apply. That is, columns not named in the `GROUP BY'
clause cannot be used in the `SELECT' list or `HAVING' clause if not
used in an aggregate function.

The select list extension also applies to `ORDER BY'. That is, you can
use non-aggregated columns or calculations in the `ORDER BY' clause
that do not appear in the `GROUP BY' clause. This extension does not
apply if the `ONLY_FULL_GROUP_BY' SQL mode is enabled.

In some cases, you can use `MIN()' and `MAX()' to obtain a specific
column value even if it isn't unique. The following gives the value of
`column' from the row containing the smallest value in the `sort'
column:

     SUBSTR(MIN(CONCAT(RPAD(sort,6,' '),column)),7)

See *Note example-maximum-column-group-row::.

Note that if you are trying to follow standard SQL, you can't use
expressions in `GROUP BY' clauses. You can work around this limitation
by using an alias for the expression:

     SELECT id,FLOOR(value/100) AS val
       FROM TBL_NAME
       GROUP BY id, val;

MySQL does allow expressions in `GROUP BY' clauses. For example:

     SELECT id,FLOOR(value/100)
       FROM TBL_NAME
       GROUP BY id, FLOOR(value/100);


File: manual.info,  Node: sql-syntax,  Next: storage-engines,  Prev: functions,  Up: Top

12 SQL Statement Syntax
***********************

* Menu:

* sql-syntax-data-definition::   Data Definition Statements
* sql-syntax-data-manipulation::  Data Manipulation Statements
* sql-syntax-utility::           MySQL Utility Statements
* sql-syntax-transactions::      MySQL Transactional and Locking Statements
* sql-syntax-server-administration::  Database Administration Statements
* sql-syntax-replication::       Replication Statements
* sql-syntax-prepared-statements::  SQL Syntax for Prepared Statements

This chapter describes the syntax for most of the SQL statements
supported by MySQL. Additional statement descriptions can be found in
the following chapters:

   * Statements for writing stored routines are covered in *Note
     stored-procedures::.

   * Statements for writing triggers are covered in *Note triggers::.

   * View-related statements are covered in *Note views::.

   * Statements for scheduling events are covered in *Note events::.


File: manual.info,  Node: sql-syntax-data-definition,  Next: sql-syntax-data-manipulation,  Prev: sql-syntax,  Up: sql-syntax

12.1 Data Definition Statements
===============================

* Menu:

* alter-database::               `ALTER DATABASE' Syntax
* alter-logfile-group::          `ALTER LOGFILE GROUP' Syntax
* alter-server::                 `ALTER SERVER' Syntax
* alter-table::                  `ALTER TABLE' Syntax
* alter-tablespace::             `ALTER TABLESPACE' Syntax
* create-database::              `CREATE DATABASE' Syntax
* create-index::                 `CREATE INDEX' Syntax
* create-logfile-group::         `CREATE LOGFILE GROUP' Syntax
* create-server::                `CREATE SERVER' Syntax
* create-table::                 `CREATE TABLE' Syntax
* create-tablespace::            `CREATE TABLESPACE' Syntax
* drop-database::                `DROP DATABASE' Syntax
* drop-index::                   `DROP INDEX' Syntax
* drop-logfile-group::           `DROP LOGFILE GROUP' Syntax
* drop-server::                  `DROP SERVER' Syntax
* drop-table::                   `DROP TABLE' Syntax
* drop-tablespace::              `DROP TABLESPACE' Syntax
* rename-database::              `RENAME DATABASE' Syntax
* rename-table::                 `RENAME TABLE' Syntax


File: manual.info,  Node: alter-database,  Next: alter-logfile-group,  Prev: sql-syntax-data-definition,  Up: sql-syntax-data-definition

12.1.1 `ALTER DATABASE' Syntax
------------------------------

     ALTER {DATABASE | SCHEMA} [DB_NAME]
         ALTER_SPECIFICATION ...
     ALTER {DATABASE | SCHEMA} DB_NAME
         UPGRADE DATA DIRECTORY NAME

     ALTER_SPECIFICATION:
         [DEFAULT] CHARACTER SET [=] CHARSET_NAME
       | [DEFAULT] COLLATE [=] COLLATION_NAME

`ALTER DATABASE' enables you to change the overall characteristics of a
database. These characteristics are stored in the `db.opt' file in the
database directory. To use `ALTER DATABASE', you need the `ALTER'
privilege on the database. `ALTER SCHEMA' is a synonym for `ALTER
DATABASE'.

The `CHARACTER SET' clause changes the default database character set.
The `COLLATE' clause changes the default database collation. *Note
charset::, discusses character set and collation names.

You can see what character sets and collations are available using,
respectively, the `SHOW CHARACTER SET' and `SHOW COLLATION' statements.
See *Note show-character-set::, and *Note show-collation::, for more
information.

The database name can be omitted from the first syntax, in which case
the statement applies to the default database.

The syntax that includes the `UPGRADE DATA DIRECTORY NAME' clause was
added in MySQL 5.1.23. It updates the name of the directory associated
with the database to use the encoding implemented in MySQL 5.1 for
mapping database names to database directory names (see *Note
identifier-mapping::). This clause is for use under these conditions:

   * It is intended when upgrading MySQL to 5.1 or later from older
     versions.

   * It is intended to update a database directory name to the current
     encoding format if the name contains special characters that need
     encoding.

   * The statement is used by `mysqlcheck' (as invoked by
     `mysql_upgrade').

For example,if a database in MySQL 5.0 has a name of `a-b-c', the name
contains instance of the ``-'' character. In 5.0, the database
directory is also named `a-b-c', which is not necessarily safe for all
filesystems. In MySQL 5.1 and up, the same database name is encoded as
`a@002db@002dc' to produce a filesystem-neutral directory name.

When a MySQL installation is upgraded to MySQL 5.1 or later from an
older version,the server displays a name such as `a-b-c' (which is in
the old format) as `#mysql50#a-b-c', and you must refer to the name
using the `#mysql50#' prefix. Use `UPGRADE DATA DIRECTORY NAME' in this
case to explicitly tell the server to re-encode the database directory
name to the current encoding format:

     ALTER DATABASE `#mysql50#a-b-c` UPGRADE DATA DIRECTORY NAME;

After executing this statement, you can refer to the database as
`a-b-c' without the special `#mysql50#' prefix.

MySQL Enterprise

In a production environment, alteration of a database is not a common
occurrence and may indicate a security breach. Advisors provided as
part of the MySQL Enterprise Monitor automatically alert you when data
definition statements are issued. For more information, see
`advisors.html'.


File: manual.info,  Node: alter-logfile-group,  Next: alter-server,  Prev: alter-database,  Up: sql-syntax-data-definition

12.1.2 `ALTER LOGFILE GROUP' Syntax
-----------------------------------

     ALTER LOGFILE GROUP LOGFILE_GROUP
         ADD UNDOFILE 'FILE_NAME'
         [INITIAL_SIZE [=] SIZE]
         [WAIT]
         ENGINE [=] ENGINE_NAME

This statement adds an `UNDO' file named 'FILE_NAME' to an existing log
file group LOGFILE_GROUP. An `ALTER LOGFILE GROUP' statement has one
and only one `ADD UNDOFILE' clause. No `DROP UNDOFILE' clause is
supported.

The optional `INITIAL_SIZE' parameter sets the `UNDO' file's initial
size in bytes; if not specified, the initial size default to `128M'
(128 megabytes). You may optionally follow SIZE with a one-letter
abbreviation for an order of magnitude, similar to those used in
`my.cnf'. Generally, this is one of the letters `M' (for megabytes) or
`G' (for gigabytes).

On 32-bit systems, the maximum supported value for `INITIAL_SIZE' is
`4G'. (Bug#29186 (http://bugs.mysql.com/29186))

`WAIT' is parsed but otherwise ignored, and so has no effect in MySQL
5.1. It is intended for future expansion.

The `ENGINE' parameter (required) determines the storage engine which
is used by this log file group, with ENGINE_NAME being the name of the
storage engine. In MySQL 5.1, the only accepted values for ENGINE_NAME
are `NDB' and `NDBCLUSTER'.

Here is an example, which assumes that the log file group `lg_3' has
already been created using `CREATE LOGFILE GROUP' (see *Note
create-logfile-group::):

     ALTER LOGFILE GROUP lg_3
         ADD UNDOFILE 'undo_10.dat'
         INITIAL_SIZE=32M
         ENGINE=NDB;

When `ALTER LOGFILE GROUP' is used with `ENGINE = NDB', an `UNDO' log
file is created on each Cluster data node. You can verify that the
`UNDO' files were created and obtain information about them by querying
the `INFORMATION_SCHEMA.FILES' table. For example:

     mysql> SELECT FILE_NAME, LOGFILE_GROUP_NUMBER, EXTRA
         -> FROM INFORMATION_SCHEMA.FILES
         -> WHERE LOGFILE_GROUP_NAME = 'lg_3';
     +-------------+----------------------+----------------+
     | FILE_NAME   | LOGFILE_GROUP_NUMBER | EXTRA          |
     +-------------+----------------------+----------------+
     | newdata.dat |                    0 | CLUSTER_NODE=3 |
     | newdata.dat |                    0 | CLUSTER_NODE=4 |
     | undo_10.dat |                   11 | CLUSTER_NODE=3 |
     | undo_10.dat |                   11 | CLUSTER_NODE=4 |
     +-------------+----------------------+----------------+
     4 rows in set (0.01 sec)

(See *Note files-table::.)

`ALTER LOGFILE GROUP' was added in MySQL 5.1.6.  In MySQL 5.1, it is
useful only with Disk Data storage for MySQL Cluster. See *Note
mysql-cluster-disk-data::.


File: manual.info,  Node: alter-server,  Next: alter-table,  Prev: alter-logfile-group,  Up: sql-syntax-data-definition

12.1.3 `ALTER SERVER' Syntax
----------------------------

     ALTER SERVER  SERVER_NAME
         OPTIONS (OPTION [, OPTION] ...)

Alters the server information for `SERVER_NAME', adjusting the
specified options as per the `CREATE SERVER' command. See *Note
create-server::. The corresponding fields in the `mysql.servers' table
are updated accordingly. This statement requires the `SUPER' privilege.

For example, to update the `USER' option:

     ALTER SERVER s OPTIONS (USER 'sally');

`ALTER SERVER' does not cause an automatic commit.

`ALTER SERVER' was added in MySQL 5.1.15.


File: manual.info,  Node: alter-table,  Next: alter-tablespace,  Prev: alter-server,  Up: sql-syntax-data-definition

12.1.4 `ALTER TABLE' Syntax
---------------------------

     ALTER [ONLINE | OFFLINE] [IGNORE] TABLE TBL_NAME
         ALTER_SPECIFICATION [, ALTER_SPECIFICATION] ...

     ALTER_SPECIFICATION:
         TABLE_OPTION ...
       | ADD [COLUMN] COL_NAME COLUMN_DEFINITION
             [FIRST | AFTER COL_NAME ]
       | ADD [COLUMN] (COL_NAME COLUMN_DEFINITION,...)
       | ADD {INDEX|KEY} [INDEX_NAME]
             [INDEX_TYPE] (INDEX_COL_NAME,...) [INDEX_OPTION] ...
       | ADD [CONSTRAINT [SYMBOL]] PRIMARY KEY
             [INDEX_TYPE] (INDEX_COL_NAME,...) [INDEX_OPTION] ...
       | ADD [CONSTRAINT [SYMBOL]]
             UNIQUE [INDEX|KEY] [INDEX_NAME]
             [INDEX_TYPE] (INDEX_COL_NAME,...) [INDEX_OPTION] ...
       | ADD FULLTEXT [INDEX|KEY] [INDEX_NAME]
             (INDEX_COL_NAME,...) [INDEX_OPTION] ...
       | ADD SPATIAL [INDEX|KEY] [INDEX_NAME]
             (INDEX_COL_NAME,...) [INDEX_OPTION] ...
       | ADD [CONSTRAINT [SYMBOL]]
             FOREIGN KEY [INDEX_NAME] (INDEX_COL_NAME,...)
             REFERENCE_DEFINITION
       | ALTER [COLUMN] COL_NAME {SET DEFAULT LITERAL | DROP DEFAULT}
       | CHANGE [COLUMN] OLD_COL_NAME NEW_COL_NAME COLUMN_DEFINITION
             [FIRST|AFTER COL_NAME]
       | MODIFY [COLUMN] COL_NAME COLUMN_DEFINITION
             [FIRST | AFTER COL_NAME]
       | DROP [COLUMN] COL_NAME
       | DROP PRIMARY KEY
       | DROP {INDEX|KEY} INDEX_NAME
       | DROP FOREIGN KEY FK_SYMBOL
       | DISABLE KEYS
       | ENABLE KEYS
       | RENAME [TO] NEW_TBL_NAME
       | ORDER BY COL_NAME [, COL_NAME] ...
       | CONVERT TO CHARACTER SET CHARSET_NAME [COLLATE COLLATION_NAME]
       | [DEFAULT] CHARACTER SET [=] CHARSET_NAME [COLLATE [=] COLLATION_NAME]
       | DISCARD TABLESPACE
       | IMPORT TABLESPACE
       | PARTITION_OPTIONS
       | ADD PARTITION (PARTITION_DEFINITION)
       | DROP PARTITION PARTITION_NAMES
       | COALESCE PARTITION NUMBER
       | REORGANIZE PARTITION PARTITION_NAMES INTO (PARTITION_DEFINITIONS)
       | ANALYZE PARTITION PARTITION_NAMES
       | CHECK PARTITION PARTITION_NAMES
       | OPTIMIZE PARTITION PARTITION_NAMES
       | REBUILD PARTITION PARTITION_NAMES
       | REPAIR PARTITION PARTITION_NAMES
       | REMOVE PARTITIONING

     INDEX_COL_NAME:
         COL_NAME [(LENGTH)] [ASC | DESC]

     INDEX_TYPE:
         USING {BTREE | HASH | RTREE}

     INDEX_OPTION:
         KEY_BLOCK_SIZE [=] VALUE
       | INDEX_TYPE
       | WITH PARSER PARSER_NAME
       | COMMENT 'STRING'

`ALTER TABLE' enables you to change the structure of an existing table.
For example, you can add or delete columns, create or destroy indexes,
change the type of existing columns, or rename columns or the table
itself. You can also change the comment for the table and type of the
table.

The syntax for many of the allowable alterations is similar to clauses
of the `CREATE TABLE' statement. See *Note create-table::, for more
information.

Some operations may result in warnings if attempted on a table for
which the storage engine does not support the operation. These warnings
can be displayed with `SHOW WARNINGS'.  See *Note show-warnings::.

In most cases, `ALTER TABLE' works by making a temporary copy of the
original table. The alteration is performed on the copy, and then the
original table is deleted and the new one is renamed. While `ALTER
TABLE' is executing, the original table is readable by other clients.
Updates and writes to the table are stalled until the new table is
ready, and then are automatically redirected to the new table without
any failed updates. The temporary table is created in the database
directory of the new table. This can be different from the database
directory of the original table if `ALTER TABLE' is renaming the table
to a different database.

In some cases, no temporary table is necessary:

   * Alterations that modify only table metadata and not table data can
     be made immediately by altering the table's `.frm' file and not
     touching table contents. The following changes are fast
     alterations that can be made this way:

        * Renaming a column or index.

        * Changing the default value of a column.

        * Changing the definition of an `ENUM' or `SET' column by
          adding new enumeration or set members to the _end_ of the
          list of valid member values.

     In some cases, an operation such as changing a `VARCHAR(10)'
     column to `VARCHAR(15)' may be immediate, but this depends on the
     storage engine for the table. A change such as `VARCHAR(10)' to a
     length greater than 255 is not immediate because data values must
     be modified from using one byte to store the length to using two
     bytes.

   * If you use `ALTER TABLE TBL_NAME RENAME TO NEW_TBL_NAME' without
     any other options, MySQL simply renames any files that correspond
     to the table TBL_NAME. (You can also use the `RENAME TABLE'
     statement to rename tables. See *Note rename-table::.) Any
     privileges granted specifically for the renamed table are not
     migrated to the new name. They must be changed manually.

   * `ALTER TABLE ... ADD PARTITION' creates no temporary table except
     for MySQL Cluster.  `ADD' or `DROP' operations for `RANGE' or
     `LIST' partitions are immediate operations or nearly so.  `ADD' or
     `COALESCE' operations for `HASH' or `KEY' partitions copy data
     between changed partitions; unless `LINEAR HASH' or `LINEAR KEY'
     was used, this is much the same as creating a new table (although
     the operation is done partition by partition). `REORGANIZE'
     operations copy only changed partitions and do not touch unchanged
     ones.

If other cases, MySQL creates a temporary table, even if the data
wouldn't strictly need to be copied. For `MyISAM' tables, you can speed
up the index re-creation operation (which is the slowest part of the
alteration process) by setting the `myisam_sort_buffer_size' system
variable to a high value.

For information on troubleshooting `ALTER TABLE', see *Note
alter-table-problems::.

   * To use `ALTER TABLE', you need `ALTER', `INSERT', and `CREATE'
     privileges for the table.

   * Beginning with MySQL 5.1.7, `ADD INDEX' and `DROP INDEX'
     operations are performed online when the indexes are on
     variable-width columns only.

     The `ONLINE' keyword can be used to perform online `ADD COLUMN',
     `ADD INDEX', and `DROP INDEX' operations on `NDB' tables beginning
     with MySQL Cluster NDB 6.2.5 and MySQL Cluster NDB 6.3.3, as well
     as online renaming of tables and columns. Online renaming
     operations (but not online adding or dropping of columns or
     indexes) are also supported for `MyISAM' tables. Online operations
     are non-copying; that is, they do not require that indexes be
     re-created, and they do not lock the table being changed. Such
     operations do not require single user mode for `NDB' table
     alterations made in a cluster with multiple API nodes;
     transactions can continue uninterrupted during online DDL
     operations.

     The `ONLINE' and `OFFLINE' keywords are supported only in MySQL
     Cluster NDB 6.2 and 6.3 (beginning with versions 6.2.5 and 6.3.3).
     In other versions of MySQL (5.1.17 and later):

       1. The server determines automatically whether an `ADD INDEX' or
          `DROP INDEX' operation can be (and is) performed online or
          offline; if the column is of a variable-width data type, then
          the operation is performed online. It is not possible to
          override the server behavior in this regard.

       2. Attempting to use the `ONLINE' or `OFFLINE' keyword in an
          `ALTER TABLE' statement results in an error.

     Limitations

     Online `ALTER TABLE' operations that add columns are subject to
     the following limitations:

        * The table to be altered must have an explicit primary key;
          the hidden primary key created by the `NDB' storage engine is
          not sufficient for this purpose. Columns to be added online
          must meet the following criteria:

             * Such columns must be dynamic; that is, it must be
               possible to create them using `COLUMN_FORMAT DYNAMIC'.

             * Such columns must be nullable, and not have any explicit
               default value other than `NULL'. Columns added online are
               automatically created as `DEFAULT NULL', as can be seen
               here:

                    mysql> CREATE TABLE t1 (
                         >     c1 INT NOT NULL AUTO_INCREMENT PRIMARY KEY
                         >     ) ENGINE=NDBCLUSTER;
                    Query OK, 0 rows affected (1.44 sec)

                    mysql> ALTER ONLINE TABLE t1
                         >     ADD COLUMN c2 INT,
                         >     ADD COLUMN c3 INT;
                    Query OK, 0 rows affected, 2 warnings (0.93 sec)

                    mysql> SHOW CREATE TABLE t2\G
                    *************************** 1. row ***************************
                           Table: t2
                    Create Table: CREATE TABLE `t2` (
                      `c1` int(11) NOT NULL AUTO_INCREMENT,
                      `c2` int(11) DEFAULT NULL,
                      `c3` int(11) DEFAULT NULL,
                      PRIMARY KEY (`c1`)
                    ) ENGINE=ndbcluster DEFAULT CHARSET=latin1
                    1 row in set (0.00 sec)

             * Columns must be added following any existing columns. If
               you attempt to add a column online before any existing
               columns, the statement fails with an error. Trying to
               add a column online using the `FIRST' keyword also fails.

               In addition, existing table columns cannot be reordered
               online.

             * The storage engine used by the table cannot be changed
               online.

          These limitations do not apply to operations that merely
          rename tables or columns.

          If the storage engine supports online `ALTER TABLE', then
          fixed-format columns will be converted to dynamic when
          columns are added online, or when indexes are created or
          dropped online, as shown here:

               mysql> CREATE TABLE t1 (c1 INT NOT NULL AUTO_INCREMENT PRIMARY KEY) ENGINE=NDB;
               Query OK, 0 rows affected (1.44 sec)

               mysql> ALTER ONLINE TABLE t1 ADD COLUMN c2 INT, ADD COLUMN c3 INT;
               Query OK, 0 rows affected, 2 warnings (0.93 sec)
               Records: 0  Duplicates: 0  Warnings: 0

               mysql> SHOW WARNINGS;
               +---------+------+---------------------------------------------------------------+
               | Level   | Code | Message                                                       |
               +---------+------+---------------------------------------------------------------+
               | Warning | 1475 | Converted FIXED field to DYNAMIC to enable on-line ADD COLUMN |
               | Warning | 1475 | Converted FIXED field to DYNAMIC to enable on-line ADD COLUMN |
               +---------+------+---------------------------------------------------------------+
               2 rows in set (0.00 sec)

          *Note*:

          Existing columns, including the table's primary key, need not
          be dynamic; only the column or columns to be added online
          must be dynamic.

               mysql> CREATE TABLE t2 (
                    >     c1 INT NOT NULL AUTO_INCREMENT PRIMARY KEY COLUMN_FORMAT FIXED
                    >     ) ENGINE=NDB;
               Query OK, 0 rows affected (2.10 sec)

               mysql> ALTER ONLINE TABLE t2 ADD COLUMN c2 INT;
               Query OK, 0 rows affected, 1 warning (0.78 sec)
               Records: 0  Duplicates: 0  Warnings: 0

               mysql> SHOW WARNINGS;
               +---------+------+---------------------------------------------------------------+
               | Level   | Code | Message                                                       |
               +---------+------+---------------------------------------------------------------+
               | Warning | 1475 | Converted FIXED field to DYNAMIC to enable on-line ADD COLUMN |
               +---------+------+---------------------------------------------------------------+
               1 row in set (0.00 sec)

          Columns are not converted from `FIXED' to `DYNAMIC' column
          format by renaming operations. For more information about
          `COLUMN_FORMAT', see *Note create-table::.

        * Online `DROP COLUMN' operations are not supported.

        * A given online `ALTER TABLE' can use only one of `ADD COLUMN',
          `ADD INDEX', or `DROP INDEX'. One or more columns can be added
          online in a single statement; only one index may be created
          or dropped online in a single statement.

     The `KEY', `CONSTRAINT', and `IGNORE' keywords are supported in
     `ALTER TABLE' statements using the `ONLINE' keyword.

     The `ONLINE' and `OFFLINE' keywords are also supported in `ALTER
     TABLE ... CHANGE ...' statements that rename columns.

     *Note*:

     The `CREATE INDEX' and `DROP INDEX' statements also support online
     operations, as well as the `ONLINE' and `OFFLINE' keywords. See
     *Note create-index::, and *Note drop-index::, for more information.

   * `IGNORE' is a MySQL extension to standard SQL. It controls how
     `ALTER TABLE' works if there are duplicates on unique keys in the
     new table or if warnings occur when strict mode is enabled. If
     `IGNORE' is not specified, the copy is aborted and rolled back if
     duplicate-key errors occur. If `IGNORE' is specified, only the
     first row is used of rows with duplicates on a unique key, The
     other conflicting rows are deleted. Incorrect values are truncated
     to the closest matching acceptable value.

   * TABLE_OPTION signifies a table option of the kind that can be used
     in the `CREATE TABLE' statement, such as `ENGINE',
     `AUTO_INCREMENT', or `AVG_ROW_LENGTH'.  (*Note create-table::,
     lists all table options.)  However, `ALTER TABLE' ignores the
     `DATA DIRECTORY' and `INDEX DIRECTORY' table options.

     For example, to convert a table to be an `InnoDB' table, use this
     statement:

          ALTER TABLE t1 ENGINE = InnoDB;

     The outcome of attempting to change a table's storage engine is
     affected by whether the desired storage engine is available and
     the setting of the `NO_ENGINE_SUBSTITUTION' SQL mode, as described
     in *Note server-sql-mode::.

     As of MySQL 5.1.11, to prevent inadvertent loss of data, `ALTER
     TABLE' cannot be used to change the storage engine of a table to
     `MERGE' or `BLACKHOLE'.

     To change the value of the `AUTO_INCREMENT' counter to be used for
     new rows, do this:

          ALTER TABLE t2 AUTO_INCREMENT = VALUE;

     You cannot reset the counter to a value less than or equal to any
     that have already been used. For `MyISAM', if the value is less
     than or equal to the maximum value currently in the
     `AUTO_INCREMENT' column, the value is reset to the current maximum
     plus one. For `InnoDB', _if the value is less than the current
     maximum value in the column, no error occurs and the current
     sequence value is not changed._

   * You can issue multiple `ADD', `ALTER', `DROP', and `CHANGE'
     clauses in a single `ALTER TABLE' statement, separated by commas.
     This is a MySQL extension to standard SQL, which allows only one
     of each clause per `ALTER TABLE' statement. For example, to drop
     multiple columns in a single statement, do this:

          ALTER TABLE t2 DROP COLUMN c, DROP COLUMN d;

   * `CHANGE COL_NAME', `DROP COL_NAME', and `DROP INDEX' are MySQL
     extensions to standard SQL.

   * `MODIFY' is an Oracle extension to `ALTER TABLE'.

   * The word `COLUMN' is optional and can be omitted.

   * COLUMN_DEFINITION clauses use the same syntax for `ADD' and
     `CHANGE' as for `CREATE TABLE'. See *Note create-table::.

   * You can rename a column using a `CHANGE OLD_COL_NAME NEW_COL_NAME
     COLUMN_DEFINITION' clause.  To do so, specify the old and new
     column names and the definition that the column currently has. For
     example, to rename an `INTEGER' column from `a' to `b', you can do
     this:

          ALTER TABLE t1 CHANGE a b INTEGER;

     If you want to change a column's type but not the name, `CHANGE'
     syntax still requires an old and new column name, even if they are
     the same. For example:

          ALTER TABLE t1 CHANGE b b BIGINT NOT NULL;

     You can also use `MODIFY' to change a column's type without
     renaming it:

          ALTER TABLE t1 MODIFY b BIGINT NOT NULL;

   * If you use `CHANGE' or `MODIFY' to shorten a column for which an
     index exists on the column, and the resulting column length is
     less than the index length, MySQL shortens the index automatically.

   * When you change a data type using `CHANGE' or `MODIFY', MySQL
     tries to convert existing column values to the new type as well as
     possible.

     *Warning*:

     This conversion may result in alteration of data. For example, if
     you shorten a string column, values may be truncated. To prevent
     the operation from succeeding if conversions to the new data type
     would result in loss of data, enable strict SQL mode before using
     `ALTER TABLE' (see *Note server-sql-mode::).

   * To add a column at a specific position within a table row, use
     `FIRST' or `AFTER COL_NAME'. The default is to add the column
     last. You can also use `FIRST' and `AFTER' in `CHANGE' or `MODIFY'
     operations to reorder columns within a table.

   * `ALTER ... SET DEFAULT' or `ALTER ...  DROP DEFAULT' specify a new
     default value for a column or remove the old default value,
     respectively. If the old default is removed and the column can be
     `NULL', the new default is `NULL'. If the column cannot be `NULL',
     MySQL assigns a default value as described in *Note
     data-type-defaults::.

   * `DROP INDEX' removes an index. This is a MySQL extension to
     standard SQL. See *Note drop-index::. If you are unsure of the
     index name, use `SHOW INDEX FROM TBL_NAME'.

   * If columns are dropped from a table, the columns are also removed
     from any index of which they are a part. If all columns that make
     up an index are dropped, the index is dropped as well.

   * If a table contains only one column, the column cannot be dropped.
     If what you intend is to remove the table, use `DROP TABLE'
     instead.

   * `DROP PRIMARY KEY' drops the primary key. If there is no primary
     key, an error occurs.

     If you add a `UNIQUE INDEX' or `PRIMARY KEY' to a table, it is
     stored before any non-unique index so that MySQL can detect
     duplicate keys as early as possible.

   * Some storage engines allow you to specify an index type when
     creating an index. The syntax for the INDEX_TYPE specifier is
     `USING TYPE_NAME'.  For details about `USING', see *Note
     create-index::. Before MySQL 5.1.10, `USING' can be given only
     before the index column list. As of 5.1.10, the preferred position
     is after the column list. Use of the option before the column list
     will no longer be recognized as of MySQL 5.3.

     INDEX_OPTION values specify additional options for an index.
     `USING' is one such option. For details about allowable
     INDEX_OPTION values, see *Note create-index::.

   * After an `ALTER TABLE' statement, it may be necessary to run
     `ANALYZE TABLE' to update index cardinality information. See *Note
     show-index::.

   * `ORDER BY' enables you to create the new table with the rows in a
     specific order. Note that the table does not remain in this order
     after inserts and deletes. This option is useful primarily when
     you know that you are mostly to query the rows in a certain order
     most of the time. By using this option after major changes to the
     table, you might be able to get higher performance. In some cases,
     it might make sorting easier for MySQL if the table is in order by
     the column that you want to order it by later.

     `ORDER BY' syntax allows for one or more column names to be
     specified for sorting, each of which optionally can be followed by
     `ASC' or `DESC' to indicate ascending or descending sort order,
     respectively. The default is ascending order. Only column names
     are allowed as sort criteria; arbitrary expressions are not
     allowed.

     `ORDER BY' does not make sense for `InnoDB' tables that contain a
     user-defined clustered index (`PRIMARY KEY' or `NOT NULL UNIQUE'
     index).  `InnoDB' always orders table rows according to such an
     index if one is present.

     *Note*:

     When used on a partitioned table, `ALTER TABLE ...  ORDER BY'
     orders rows within each partition only.

   * If you use `ALTER TABLE' on a `MyISAM' table, all non-unique
     indexes are created in a separate batch (as for `REPAIR TABLE').
     This should make `ALTER TABLE' much faster when you have many
     indexes.

     This feature can be activated explicitly for a `MyISAM' table.
     `ALTER TABLE ...  DISABLE KEYS' tells MySQL to stop updating
     non-unique indexes. `ALTER TABLE ... ENABLE KEYS' then should be
     used to re-create missing indexes. MySQL does this with a special
     algorithm that is much faster than inserting keys one by one, so
     disabling keys before performing bulk insert operations should
     give a considerable speedup. Using `ALTER TABLE ... DISABLE KEYS'
     requires the `INDEX' privilege in addition to the privileges
     mentioned earlier.

     While the non-unique indexes are disabled, they are ignored for
     statements such as `SELECT' and `EXPLAIN' that otherwise would use
     them.

     `ENABLE KEYS' and `DISABLE KEYS' were not supported for
     partitioned tables prior to MySQL 5.1.11.

   * If `ALTER TABLE' for an `InnoDB' table results in changes to column
     values (for example, because a column is truncated), `InnoDB''s
     `FOREIGN KEY' constraint checks do not notice possible violations
     caused by changing the values.

   * The `FOREIGN KEY' and `REFERENCES' clauses are supported by the
     `InnoDB' storage engine, which implements `ADD [CONSTRAINT
     [SYMBOL]] FOREIGN KEY (...) REFERENCES ... (...)'. See *Note
     innodb-foreign-key-constraints::. For other storage engines, the
     clauses are parsed but ignored. The `CHECK' clause is parsed but
     ignored by all storage engines. See *Note create-table::. The
     reason for accepting but ignoring syntax clauses is for
     compatibility, to make it easier to port code from other SQL
     servers, and to run applications that create tables with
     references. See *Note differences-from-ansi::.

     *Important*:

     The inline `REFERENCES' specifications where the references are
     defined as part of the column specification are silently ignored by
     `InnoDB'. InnoDB only accepts `REFERENCES' clauses defined as part
     of a separate `FOREIGN KEY' specification.

     *Note*:

     Partitioned tables do not support foreign keys. See *Note
     partitioning-limitations::, for more information.

   * `InnoDB' supports the use of `ALTER TABLE' to drop foreign keys:

          ALTER TABLE TBL_NAME DROP FOREIGN KEY FK_SYMBOL;

     For more information, see *Note innodb-foreign-key-constraints::.

   * You cannot add a foreign key and drop a foreign key in separate
     clauses of a single `ALTER TABLE' statement. You must use separate
     statements.

   * For an `InnoDB' table that is created with its own tablespace in
     an `.ibd' file, that file can be discarded and imported. To
     discard the `.ibd' file, use this statement:

          ALTER TABLE TBL_NAME DISCARD TABLESPACE;

     This deletes the current `.ibd' file, so be sure that you have a
     backup first. Attempting to access the table while the tablespace
     file is discarded results in an error.

     To import the backup `.ibd' file back into the table, copy it into
     the database directory, and then issue this statement:

          ALTER TABLE TBL_NAME IMPORT TABLESPACE;

     See *Note multiple-tablespaces::.

   * Pending `INSERT DELAYED' statements are lost if a table is write
     locked and `ALTER TABLE' is used to modify the table structure.

   * If you want to change the table default character set and all
     character columns (`CHAR', `VARCHAR', `TEXT') to a new character
     set, use a statement like this:

          ALTER TABLE TBL_NAME CONVERT TO CHARACTER SET CHARSET_NAME;

     For a column that has a data type of `VARCHAR' or one of the
     `TEXT' types, `CONVERT TO CHARACTER SET' will change the data type
     as necessary to ensure that the new column is long enough to store
     as many characters as the original column. For example, a `TEXT'
     column has two length bytes, which store the byte-length of values
     in the column, up to a maximum of 65,535. For a `latin1' `TEXT'
     column, each character requires a single byte, so the column can
     store up to 65,535 characters. If the column is converted to
     `utf8', each character might require up to three bytes, for a
     maximum possible length of 3 x 65,535 = 196,605 bytes. That length
     will not fit in a `TEXT' column's length bytes, so MySQL will
     convert the data type to `MEDIUMTEXT', which is the smallest
     string type for which the length bytes can record a value of
     196,605. Similarly, a `VARCHAR' column might be converted to
     `MEDIUMTEXT'.

     To avoid data type changes of the type just described, do not use
     `CONVERT TO CHARACTER SET'. Instead, use `MODIFY' to change
     individual columns. For example:

          ALTER TABLE t MODIFY latin1_text_col TEXT CHARACTER SET utf8;
          ALTER TABLE t MODIFY latin1_varchar_col VARCHAR(M) CHARACTER SET utf8;

     If you specify `CONVERT TO CHARACTER SET binary', the `CHAR',
     `VARCHAR', and `TEXT' columns are converted to their corresponding
     binary string types (`BINARY', `VARBINARY', `BLOB'). This means
     that the columns no longer will have a character set and a
     subsequent `CONVERT TO' operation will not apply to them.

     If CHARSET_NAME is `DEFAULT', the database character set is used.

     *Warning*:

     The `CONVERT TO' operation converts column values between the
     character sets. This is _not_ what you want if you have a column
     in one character set (like `latin1') but the stored values
     actually use some other, incompatible character set (like `utf8').
     In this case, you have to do the following for each such column:

          ALTER TABLE t1 CHANGE c1 c1 BLOB;
          ALTER TABLE t1 CHANGE c1 c1 TEXT CHARACTER SET utf8;

     The reason this works is that there is no conversion when you
     convert to or from `BLOB' columns.

     To change only the _default_ character set for a table, use this
     statement:

          ALTER TABLE TBL_NAME DEFAULT CHARACTER SET CHARSET_NAME;

     The word `DEFAULT' is optional. The default character set is the
     character set that is used if you do not specify the character set
     for columns that you add to a table later (for example, with
     `ALTER TABLE ... ADD column').

   * A number of partitioning-related extensions to `ALTER TABLE' were
     added in MySQL 5.1.5. These can be used with partitioned tables
     for repartitioning, for adding, dropping, merging, and splitting
     partitions, and for performing partitioning maintenance.

     Simply using a PARTITION_OPTIONS clause with `ALTER TABLE' on a
     partitioned table repartitions the table according to the
     partitioning scheme defined by the PARTITION_OPTIONS. This clause
     always begins with `PARTITION BY', and follows the same syntax and
     other rules as apply to the PARTITION_OPTIONS clause for `CREATE
     TABLE' (see *Note create-table::, for more detailed information),
     and can also be used to partition an existing table that is not
     already partitioned. For example, consider a (non-partitioned)
     table defined as shown here:

          CREATE TABLE t1 (
              id INT,
              year_col INT
          );

     This table can be partitioned by `HASH', using the `id' column as
     the partitioning key, into 8 partitions by means of this statement:

          ALTER TABLE t1
              PARTITION BY HASH(id)
              PARTITIONS 8;

     The table that results from using an `ALTER TABLE ...  PARTITION
     BY' statement must follow the same rules as one created using
     `CREATE TABLE ... PARTITION BY'. This includes the rules governing
     the relationship between any unique keys (including any primary
     key) that the table might have, and the column or columns used in
     the partitioning expression, as discussed in *Note
     partitioning-limitations-partitioning-keys-unique-keys::.  The
     `CREATE TABLE ... PARTITION BY' rules for specifying the number of
     partitions also apply to `ALTER TABLE ... PARTITION BY'.

     `ALTER TABLE ... PARTITION BY' became available in MySQL 5.1.6.

     The PARTITION_DEFINITION clause for `ALTER TABLE ADD PARTITION'
     supports the same options as the clause of the same name for the
     `CREATE TABLE' statement. (See *Note create-table::, for the
     syntax and description.) Suppose that you have the partitioned
     table created as shown here:

          CREATE TABLE t1 (
              id INT,
              year_col INT
          )
          PARTITION BY RANGE (year_col) (
              PARTITION p0 VALUES LESS THAN (1991),
              PARTITION p1 VALUES LESS THAN (1995),
              PARTITION p2 VALUES LESS THAN (1999)
          );

     You can add a new partition `p3' to this table for storing values
     less than `2002' as follows:

          ALTER TABLE t1 ADD PARTITION (PARTITION p3 VALUES LESS THAN (2002));

     `DROP PARTITION' can be used to drop one or more `RANGE' or `LIST'
     partitions. This statement cannot be used with `HASH' or `KEY'
     partitions; instead, use `COALESCE PARTITION' (see below). Any
     data that was stored in the dropped partitions named in the
     PARTITION_NAMES list is discarded. For example, given the table
     `t1' defined previously, you can drop the partitions named `p0' and
     `p1' as shown here:

          ALTER TABLE t1 DROP PARTITION p0, p1;

     *Note*:

     `DROP PARTITION' does not work with tables that use the
     `NDBCLUSTER' storage engine.  See *Note
     partitioning-management-range-list::, and *Note
     mysql-cluster-limitations::.

     `ADD PARTITION' and `DROP PARTITION' do not currently support `IF
     [NOT] EXISTS'. It is also not possible to rename a partition or a
     partitioned table. Instead, if you wish to rename a partition, you
     must drop and re-create the partition; if you wish to rename a
     partitioned table, you must instead drop all partitions, rename
     the table, and then add back the partitions that were dropped.

     `COALESCE PARTITION' can be used with a table that is partitioned
     by `HASH' or `KEY' to reduce the number of partitions by NUMBER.
     Suppose that you have created table `t2' using the following
     definition:

          CREATE TABLE t2 (
              name VARCHAR (30),
              started DATE
          )
          PARTITION BY HASH( YEAR(started) )
          PARTITIONS 6;

     You can reduce the number of partitions used by `t2' from 6 to 4
     using the following statement:

          ALTER TABLE t2 COALESCE PARTITION 2;

     The data contained in the last NUMBER partitions will be merged
     into the remaining partitions. In this case, partitions 4 and 5
     will be merged into the first 4 partitions (the partitions
     numbered 0, 1, 2, and 3).

     To change some but not all the partitions used by a partitioned
     table, you can use `REORGANIZE PARTITION'. This statement can be
     used in several ways:

        * To merge a set of partitions into a single partition. This
          can be done by naming several partitions in the
          PARTITION_NAMES list and supplying a single definition for
          PARTITION_DEFINITION.

        * To split an existing partition into several partitions.  You
          can accomplish this by naming a single partition for
          PARTITION_NAMES and providing multiple PARTITION_DEFINITIONS.

        * To change the ranges for a subset of partitions defined using
          `VALUES LESS THAN' or the value lists for a subset of
          partitions defined using `VALUES IN'.

     *Note*:

     For partitions that have not been explicitly named, MySQL
     automatically provides the default names `p0', `p1', `p2', and so
     on. As of MySQL 5.1.7, the same is true with regard to
     subpartitions.

     For more detailed information about and examples of `ALTER TABLE
     ... REORGANIZE PARTITION' statements, see *Note
     partitioning-management::.

     *Important*:

     Only a single `PARTITION BY', `ADD PARTITION', `DROP PARTITION',
     `REORGANIZE PARTITION', or `COALESCE PARTITION' clause can be used
     in a given `ALTER TABLE' statement.

   * Several additional options were introduced in MySQL 5.1.5 for
     providing partition maintenance and repair functionality analogous
     to that implemented for non-partitioned tables by statements such
     as `CHECK TABLE' and `REPAIR TABLE' (which are _not_ supported for
     partitioned tables).  These include `ANALYZE PARTITION', `CHECK
     PARTITION', `OPTIMIZE PARTITION', `REBUILD PARTITION', and `REPAIR
     PARTITION'. Each of these options takes a PARTITION_NAMES clause
     consisting of one or more names of partitions, separated by
     commas. The partitions must already exist in the table to be
     altered. For more information and examples, see *Note
     partitioning-maintenance::.

     The `ANALYZE PARTITION', `CHECK PARTITION', `OPTIMIZE PARTITION',
     and `REPAIR PARTITION' options were removed in MySQL 5.1.24.

   * `REMOVE PARTITIONING' was introduced in MySQL 5.1.8 for the
     purpose of removing a table's partitioning without otherwise
     affecting the table or its data.  (Previously, this was done using
     the `ENGINE ' option.) This option can be combined with other
     `ALTER TABLE' options such as those used to add, drop, or rename
     drop columns or indexes.

   * In MySQL 5.1.7 and earlier, using the `ENGINE' option with `ALTER
     TABLE' caused any partitioning that a table might have had to be
     removed. Beginning with MySQL 5.1.8, this option merely changes
     the storage engine used by the table and no longer affects
     partitioning in any way.

With the *Note `mysql_info()': mysql-info. C API function, you can find
out how many rows were copied, and (when `IGNORE' is used) how many
rows were deleted due to duplication of unique key values. See *Note
mysql-info::.

Here are some examples that show uses of `ALTER TABLE'. Begin with a
table `t1' that is created as shown here:

     CREATE TABLE t1 (a INTEGER,b CHAR(10));

To rename the table from `t1' to `t2':

     ALTER TABLE t1 RENAME t2;

To change column `a' from `INTEGER' to `TINYINT NOT NULL' (leaving the
name the same), and to change column `b' from `CHAR(10)' to `CHAR(20)'
as well as renaming it from `b' to `c':

     ALTER TABLE t2 MODIFY a TINYINT NOT NULL, CHANGE b c CHAR(20);

To add a new `TIMESTAMP' column named `d':

     ALTER TABLE t2 ADD d TIMESTAMP;

To add an index on column `d' and a `UNIQUE' index on column `a':

     ALTER TABLE t2 ADD INDEX (d), ADD UNIQUE (a);

To remove column `c':

     ALTER TABLE t2 DROP COLUMN c;

To add a new `AUTO_INCREMENT' integer column named `c':

     ALTER TABLE t2 ADD c INT UNSIGNED NOT NULL AUTO_INCREMENT,
       ADD PRIMARY KEY (c);

Note that we indexed `c' (as a `PRIMARY KEY') because `AUTO_INCREMENT'
columns must be indexed, and also that we declare `c' as `NOT NULL'
because primary key columns cannot be `NULL'.

When you add an `AUTO_INCREMENT' column, column values are filled in
with sequence numbers automatically. For `MyISAM' tables, you can set
the first sequence number by executing `SET INSERT_ID=VALUE' before
`ALTER TABLE' or by using the `AUTO_INCREMENT=VALUE' table option. See
*Note server-session-variables::.

With `MyISAM' tables, if you do not change the `AUTO_INCREMENT' column,
the sequence number is not affected. If you drop an `AUTO_INCREMENT'
column and then add another `AUTO_INCREMENT' column, the numbers are
resequenced beginning with 1.

When replication is used, adding an `AUTO_INCREMENT' column to a table
might not produce the same ordering of the rows on the slave and the
master.  This occurs because the order in which the rows are numbered
depends on the specific storage engine used for the table and the order
in which the rows were inserted. If it is important to have the same
order on the master and slave, the rows must be ordered before
assigning an `AUTO_INCREMENT' number.  Assuming that you want to add an
`AUTO_INCREMENT' column to the table `t1', the following statements
produce a new table `t2' identical to `t1' but with an `AUTO_INCREMENT'
column:

     CREATE TABLE t2 (id INT AUTO_INCREMENT PRIMARY KEY)
     SELECT * FROM t1 ORDER BY col1, col2;

This assumes that the table `t1' has columns `col1' and `col2'.

This set of statements will also produce a new table `t2' identical to
`t1', with the addition of an `AUTO_INCREMENT' column:

     CREATE TABLE t2 LIKE t1;
     ALTER TABLE T2 ADD id INT AUTO_INCREMENT PRIMARY KEY;
     INSERT INTO t2 SELECT * FROM t1 ORDER BY col1, col2;

*Important*:

To guarantee the same ordering on both master and slave, _all_ columns
of `t1' must be referenced in the `ORDER BY' clause.

Regardless of the method used to create and populate the copy having
the `AUTO_INCREMENT' column, the final step is to drop the original
table and then rename the copy:

     DROP t1;
     ALTER TABLE t2 RENAME t1;


File: manual.info,  Node: alter-tablespace,  Next: create-database,  Prev: alter-table,  Up: sql-syntax-data-definition

12.1.5 `ALTER TABLESPACE' Syntax
--------------------------------

     ALTER TABLESPACE TABLESPACE_NAME
         {ADD|DROP} DATAFILE 'FILE_NAME'
         [INITIAL_SIZE [=] SIZE]
         [WAIT]
         ENGINE [=] ENGINE_NAME

This statement can be used either to add a new data file, or to drop a
data file from a tablespace.

The `ADD DATAFILE' variant allows you to specify an initial size using
an `INITIAL_SIZE' clause, where SIZE is measured in bytes; the default
value is `128M' (128 megabytes). You may optionally follow this integer
value with a one-letter abbreviation for an order of magnitude, similar
to those used in `my.cnf'. Generally, this is one of the letters `M'
(for megabytes) or `G' (for gigabytes).

On 32-bit systems, the maximum supported value for `INITIAL_SIZE' is
`4G'. (Bug#29186 (http://bugs.mysql.com/29186))

Once a data file has been created, its size cannot be changed; however,
you can add more data files to the tablespace using additional `ALTER
TABLESPACE ... ADD DATAFILE' statements.

Using `DROP DATAFILE' with `ALTER TABLESPACE' drops the data file
'FILE_NAME' from the tablespace. This file must already have been added
to the tablespace using `CREATE TABLESPACE' or `ALTER TABLESPACE';
otherwise an error will result.

Both `ALTER TABLESPACE ... ADD DATAFILE' and `ALTER TABLESPACE ... DROP
DATAFILE' require an `ENGINE' clause which specifies the storage engine
used by the tablespace. In MySQL 5.1, the only accepted values for
ENGINE_NAME are `NDB' and `NDBCLUSTER'.

`WAIT' is parsed but otherwise ignored, and so has no effect in MySQL
5.1. It is intended for future expansion.

When `ALTER TABLESPACE ... ADD DATAFILE' is used with `ENGINE = NDB', a
data file is created on each Cluster data node. You can verify that the
data files were created and obtain information about them by querying
the `INFORMATION_SCHEMA.FILES' table. For example, the following query
shows all data files belonging to the tablespace named `newts':

     mysql> SELECT LOGFILE_GROUP_NAME, FILE_NAME, EXTRA
         -> FROM INFORMATION_SCHEMA.FILES
         -> WHERE TABLESPACE_NAME = 'newts' AND FILE_TYPE = 'DATAFILE';
     +--------------------+--------------+----------------+
     | LOGFILE_GROUP_NAME | FILE_NAME    | EXTRA          |
     +--------------------+--------------+----------------+
     | lg_3               | newdata.dat  | CLUSTER_NODE=3 |
     | lg_3               | newdata.dat  | CLUSTER_NODE=4 |
     | lg_3               | newdata2.dat | CLUSTER_NODE=3 |
     | lg_3               | newdata2.dat | CLUSTER_NODE=4 |
     +--------------------+--------------+----------------+
     2 rows in set (0.03 sec)

See *Note files-table::.

`ALTER TABLESPACE' was added in MySQL 5.1.6. In MySQL 5.1, it is useful
only with Disk Data storage for MySQL Cluster. See *Note
mysql-cluster-disk-data::.


File: manual.info,  Node: create-database,  Next: create-index,  Prev: alter-tablespace,  Up: sql-syntax-data-definition

12.1.6 `CREATE DATABASE' Syntax
-------------------------------

     CREATE {DATABASE | SCHEMA} [IF NOT EXISTS] DB_NAME
         [CREATE_SPECIFICATION] ...

     CREATE_SPECIFICATION:
         [DEFAULT] CHARACTER SET [=] CHARSET_NAME
       | [DEFAULT] COLLATE [=] COLLATION_NAME

`CREATE DATABASE' creates a database with the given name. To use this
statement, you need the `CREATE' privilege for the database.  `CREATE
SCHEMA' is a synonym for `CREATE DATABASE'.

An error occurs if the database exists and you did not specify `IF NOT
EXISTS'.

CREATE_SPECIFICATION options specify database characteristics. Database
characteristics are stored in the `db.opt' file in the database
directory.  The `CHARACTER SET' clause specifies the default database
character set. The `COLLATE' clause specifies the default database
collation.  *Note charset::, discusses character set and collation
names.

A database in MySQL is implemented as a directory containing files that
correspond to tables in the database. Because there are no tables in a
database when it is initially created, the `CREATE DATABASE' statement
creates only a directory under the MySQL data directory and the
`db.opt' file. Rules for allowable database names are given in *Note
identifiers::. If a database name contains special characters, the name
for the database directory contains encoded versions of those
characters as described in *Note identifier-mapping::.

If you manually create a directory under the data directory (for
example, with `mkdir'), the server considers it a database directory
and it shows up in the output of `SHOW DATABASES'.

You can also use the `mysqladmin' program to create databases. See
*Note mysqladmin::.


File: manual.info,  Node: create-index,  Next: create-logfile-group,  Prev: create-database,  Up: sql-syntax-data-definition

12.1.7 `CREATE INDEX' Syntax
----------------------------

     CREATE [ONLINE|OFFLINE] [UNIQUE|FULLTEXT|SPATIAL] INDEX INDEX_NAME
         [INDEX_TYPE]
         ON TBL_NAME (INDEX_COL_NAME,...)
         [INDEX_OPTION] ...

     INDEX_COL_NAME:
         COL_NAME [(LENGTH)] [ASC | DESC]

     INDEX_TYPE:
         USING {BTREE | HASH | RTREE}

     INDEX_OPTION:
         KEY_BLOCK_SIZE [=] VALUE
       | INDEX_TYPE
       | WITH PARSER PARSER_NAME

`CREATE INDEX' is mapped to an `ALTER TABLE' statement to create
indexes. See *Note alter-table::. `CREATE INDEX' cannot be used to
create a `PRIMARY KEY'; use `ALTER TABLE' instead. For more information
about indexes, see *Note mysql-indexes::.

Normally, you create all indexes on a table at the time the table
itself is created with `CREATE TABLE'. See *Note create-table::.
`CREATE INDEX' enables you to add indexes to existing tables.

A column list of the form `(col1,col2,...)' creates a multiple-column
index. Index values are formed by concatenating the values of the given
columns.

Indexes can be created that use only the leading part of column values,
using `COL_NAME(LENGTH)' syntax to specify an index prefix length:

   * Prefixes can be specified for `CHAR', `VARCHAR', `BINARY', and
     `VARBINARY' columns.

   * `BLOB' and `TEXT' columns also can be indexed, but a prefix length
     _must_ be given.

   * Prefix lengths are given in characters for non-binary string types
     and in bytes for binary string types. That is, index entries
     consist of the first LENGTH characters of each column value for
     `CHAR', `VARCHAR', and `TEXT' columns, and the first LENGTH bytes
     of each column value for `BINARY', `VARBINARY', and `BLOB' columns.

   * For spatial columns, prefix values cannot be given, as described
     later in this section.

The statement shown here creates an index using the first 10 characters
of the `name' column:

     CREATE INDEX part_of_name ON customer (name(10));

If names in the column usually differ in the first 10 characters, this
index should not be much slower than an index created from the entire
`name' column. Also, using column prefixes for indexes can make the
index file much smaller, which could save a lot of disk space and might
also speed up `INSERT' operations.

Prefix lengths are storage engine-dependent (for example, a prefix can
be up to 1000 bytes long for `MyISAM' tables, 767 bytes for `InnoDB'
tables). Note that prefix limits are measured in bytes, whereas the
prefix length in `CREATE INDEX' statements is interpreted as number of
characters for non-binary data types (`CHAR', `VARCHAR', `TEXT'). Take
this into account when specifying a prefix length for a column that
uses a multi-byte character set.  For example, `utf8' columns require
up to three index bytes per character.

Beginning with MySQL 5.1.7, indexes on variable-width columns are
created online; that is, creating the indexes does not require any
copying or locking of the table. This is done automatically by the
server whenever it determines that it is possible to do so; you do not
have to use any special SQL syntax or server options to cause it to
happen.

In standard MySQL 5.1 releases, it is not possible to override the
server when it determines that an index is to be created online. In
MySQL Cluster, beginning with MySQL Cluster NDB 6.2.5 and MySQL Cluster
NDB 6.3.3, you can create indexes offline (which causes the table to be
locked) using the `OFFLINE' keyword. The rules and limitations
governing online `CREATE OFFLINE INDEX' and `CREATE ONLINE INDEX' are
the same as for `ALTER OFFLINE TABLE ... ADD INDEX' and `ALTER ONLINE
TABLE ... ADD INDEX'. You cannot cause the online creation of an index
that would normally be created offline by using the `ONLINE' keyword (if
it is not possible to perform the `CREATE INDEX' operation online, then
the `ONLINE' keyword is ignored). For more information, see *Note
alter-table::.

*Note*:

The `ONLINE' and `OFFLINE' keywords are available only in MySQL Cluster
NDB 6.2 and MySQL Cluster NDB 6.3 releases beginning with versions
6.2.5 and 6.3.3, respectively; attempting to use them in earlier MySQL
Cluster NDB 6.2 or 6.3 releases, standard MySQL 5.1 releases, or MySQL
Cluster NDB 6.1 releases results in a syntax error.

A `UNIQUE' index creates a constraint such that all values in the index
must be distinct. An error occurs if you try to add a new row with a
key value that matches an existing row. For all engines, a `UNIQUE'
index allows multiple `NULL' values for columns that can contain
`NULL'. If you specify a prefix value for a column in a `UNIQUE' index,
the column values must be unique within the prefix.

MySQL Enterprise

Lack of proper indexes can greatly reduce performance. Subscribe to the
MySQL Enterprise Monitor for notification of inefficient use of
indexes. For more information, see `advisors.html'.

`FULLTEXT' indexes are supported only for `MyISAM' tables and can
include only `CHAR', `VARCHAR', and `TEXT' columns. Indexing always
happens over the entire column; column prefix indexing is not supported
and any prefix length is ignored if specified. See *Note
fulltext-search::, for details of operation.

The `MyISAM', `InnoDB', `NDB', `BDB', and `ARCHIVE' storage engines
support spatial columns such as (`POINT' and `GEOMETRY'.  (*Note
spatial-extensions::, describes the spatial data types.) However,
support for spatial column indexing varies among engines. Spatial and
non-spatial indexes are available according to the following rules.

Spatial indexes (created using `SPATIAL INDEX'):

   * Available only for `MyISAM' tables.  Specifying a `SPATIAL INDEX'
     for other storage engines results in an error.

   * Indexed columns must be `NOT NULL'.

   * In MySQL 5.1, column prefix lengths are prohibited. The full width
     of each column is indexed.

Non-spatial indexes (created with `INDEX', `UNIQUE', or `PRIMARY KEY'):

   * Allowed for any storage engine that supports spatial columns
     except `ARCHIVE'.

   * Columns can be `NULL' unless the index is a primary key.

   * For each spatial column in a non-`SPATIAL' index except `POINT'
     columns, a column prefix length must be specified. (This is the
     same requirement as for indexed `BLOB' columns.) The prefix length
     is given in bytes.

   * The index type for a non-`SPATIAL' index depends on the storage
     engine. Currently, B-tree is used.

In MySQL 5.1:

   * You can add an index on a column that can have `NULL' values only
     if you are using the `MyISAM', `InnoDB', or `MEMORY' storage
     engine.

   * You can add an index on a `BLOB' or `TEXT' column only if you are
     using the `MyISAM', or `InnoDB' storage engine.

An INDEX_COL_NAME specification can end with `ASC' or `DESC'. These
keywords are allowed for future extensions for specifying ascending or
descending index value storage. Currently, they are parsed but ignored;
index values are always stored in ascending order.

As of MySQL 5.1.10, index options can be given following the index
column list. An INDEX_OPTION value can be any of the following:

   * `KEY_BLOCK_SIZE [=] VALUE'

     This option provides a hint to the storage engine about the size
     in bytes to use for index key blocks. The engine is allowed to
     change the value if necessary. A value of 0 indicates that the
     default value should be used.

   * INDEX_TYPE

     Some storage engines allow you to specify an index type when
     creating an index. The allowable index type values supported by
     different storage engines are shown in the following table.  Where
     multiple index types are listed, the first one is the default when
     no index type specifier is given.

     *Storage      *Allowable Index Types*
     Engine*       
     `MyISAM'      `BTREE', `RTREE'
     `InnoDB'      `BTREE'
     `MEMORY'/`HEAP'`HASH', `BTREE'
     `NDB'         `HASH', `BTREE' (see note in text)

     *Note*:

     `BTREE' indexes are implemented by the `NDBCLUSTER' storage engine
     as T-tree indexes.

     For indexes on `NDBCLUSTER' table columns, the `USING' clause can
     be specified only for a unique index or primary key. In such
     cases, the `USING HASH' clause prevents the creation of an
     implicit ordered index. Without `USING HASH', a statement defining
     a unique index or primary key automatically results in the
     creation of a `HASH' index in addition to the ordered index, both
     of which index the same set of columns.

     The `RTREE' index type is allowable only for `SPATIAL' indexes.

     If you specify an index type that is not legal for a given storage
     engine, but there is another index type available that the engine
     can use without affecting query results, the engine uses the
     available type.

     Examples:

          CREATE TABLE lookup (id INT) ENGINE = MEMORY;
          CREATE INDEX id_index USING BTREE ON lookup (id);

     `TYPE TYPE_NAME' is recognized as a synonym for `USING TYPE_NAME'.
     However, `USING' is the preferred form.

     Before MySQL 5.1.10, this option can be given only before the `ON
     TBL_NAME' clause. Use of the option in this position is deprecated
     as of 5.1.10; support for it is to be dropped in a future MySQL
     release. If an `index_type' option is given in both the earlier
     and later positions, the final option applies.

   * `WITH PARSER PARSER_NAME'

     This option can be used only with `FULLTEXT' indexes. It
     associates a parser plugin with the index if full-text indexing
     and searching operations need special handling. See *Note
     plugin-api::, for details on creating plugins.


File: manual.info,  Node: create-logfile-group,  Next: create-server,  Prev: create-index,  Up: sql-syntax-data-definition

12.1.8 `CREATE LOGFILE GROUP' Syntax
------------------------------------

     CREATE LOGFILE GROUP LOGFILE_GROUP
         ADD UNDOFILE 'UNDO_FILE'
         [INITIAL_SIZE [=] INITIAL_SIZE]
         [UNDO_BUFFER_SIZE [=] UNDO_BUFFER_SIZE]
         [REDO_BUFFER_SIZE [=] REDO_BUFFER_SIZE]
         [NODEGROUP [=] NODEGROUP_ID]
         [WAIT]
         [COMMENT [=] COMMENT_TEXT]
         ENGINE [=] ENGINE_NAME

This statement creates a new log file group named LOGFILE_GROUP having
a single `UNDO' file named 'UNDO_FILE'. A `CREATE LOGFILE GROUP'
statement has one and only one `ADD UNDOFILE' clause. For rules
covering the naming of log file groups, see *Note identifiers::.

Beginning with MySQL 5.1.8, you can have only one log file group per
Cluster at any given time. (See Bug#16386 (http://bugs.mysql.com/16386))

The optional `INITIAL_SIZE' parameter sets the `UNDO' file's initial
size; if not specified, it defaults to `128M' (128 megabytes). The
optional `UNDO_BUFFFER_SIZE' parameter sets the size used by the `UNDO'
buffer for the log file group; The default value for `UNDO_BUFFER_SIZE'
is `8M' (eight megabytes); this value cannot exceed the amount of
system memory available. Both of these parameters are specified in
bytes. You may optionally follow either or both of these with a
one-letter abbreviation for an order of magnitude, similar to those
used in `my.cnf'. Generally, this is one of the letters `M' (for
megabytes) or `G' (for gigabytes).

On 32-bit systems, the maximum supported value for `INITIAL_SIZE' is
`4G'. (Bug#29186 (http://bugs.mysql.com/29186))

The `ENGINE' parameter determines the storage engine to be used by this
log file group, with ENGINE_NAME being the name of the storage engine.
In MySQL 5.1.  ENGINE_NAME must be one of the values `NDB' or
`NDBCLUSTER'.

REDO_BUFFER_SIZE, `NODEGROUP', `WAIT', and `COMMENT' are parsed but
ignored, and so have no effect in MySQL 5.1. These options are intended
for future expansion.

When used with `ENGINE [=] NDB', a log file group and associated `UNDO'
log file are created on each Cluster data node. You can verify that the
`UNDO' files were created and obtain information about them by querying
the `INFORMATION_SCHEMA.FILES' table. For example:

     mysql> SELECT LOGFILE_GROUP_NAME, LOGFILE_GROUP_NUMBER, EXTRA
         -> FROM INFORMATION_SCHEMA.FILES
         -> WHERE FILE_NAME = 'undo_10.dat';
     +--------------------+----------------------+----------------+
     | LOGFILE_GROUP_NAME | LOGFILE_GROUP_NUMBER | EXTRA          |
     +--------------------+----------------------+----------------+
     | lg_3               |                   11 | CLUSTER_NODE=3 |
     | lg_3               |                   11 | CLUSTER_NODE=4 |
     +--------------------+----------------------+----------------+
     2 rows in set (0.06 sec)

(See *Note files-table::.)

`CREATE LOGFILE GROUP' was added in MySQL 5.1.6.  In MySQL 5.1, it is
useful only with Disk Data storage for MySQL Cluster. See *Note
mysql-cluster-disk-data::.


File: manual.info,  Node: create-server,  Next: create-table,  Prev: create-logfile-group,  Up: sql-syntax-data-definition

12.1.9 `CREATE SERVER' Syntax
-----------------------------

     CREATE SERVER SERVER_NAME
         FOREIGN DATA WRAPPER WRAPPER_NAME
         OPTIONS (OPTION [, OPTION] ...)

     OPTION:
       { HOST CHARACTER-LITERAL
       | DATABASE CHARACTER-LITERAL
       | USER CHARACTER-LITERAL
       | PASSWORD CHARACTER-LITERAL
       | SOCKET CHARACTER-LITERAL
       | OWNER CHARACTER-LITERAL
       | PORT NUMERIC-LITERAL }

This statement creates the definition of a server for use with the
`FEDERATED' storage engine. The `CREATE SERVER' statement creates a new
row within the `servers' table within the `mysql' database. This
statement requires the `SUPER' privilege.

The `SERVER_NAME' should be a unique reference to the server. Server
definitions are global within the scope of the server, it is not
possible to qualify the server definition to a specific database.
`SERVER_NAME' has a maximum length of 64 characters (names longer than
64 characters are silently truncated), and is case insensitive. You may
specify the name as a quoted string.

The `WRAPPER_NAME' should be `mysql', and may be quoted with single
quotes. Other values for `WRAPPER_NAME' are not currently supported.

For each `OPTION' you must specify either a character literal or
numeric literal.  Character literals are UTF-8, support a maximum
length of 64 characters and default to a blank (empty) string. String
literals are silently truncated to 64 characters. Numeric literals must
be a number between 0 and 9999, default value is 0.

*Note*:

Note that the `OWNER' option is currently not applied, and has no
effect on the ownership or operation of the server connection that is
created.

The `CREATE SERVER' statement creates an entry in the `mysql.server'
table that can later be used with the `CREATE TABLE' statement when
creating a `FEDERATED' table. The options that you specify will be used
to populate the columns in the `mysql.server' table. The table columns
are `Server_name', `Host', `Db', `Username', `Password', `Port' and
`Socket'.

For example:

     CREATE SERVER s
     FOREIGN DATA WRAPPER mysql
     OPTIONS (USER 'Remote', HOST '192.168.1.106', DATABASE 'test');

The data stored in the table can be used when creating a connection to
a `FEDERATED' table:

     CREATE TABLE t (s1 INT) ENGINE=FEDERATED CONNECTION='s';

For more information, see *Note federated-storage-engine::.

`CREATE SERVER' does not cause an automatic commit.

`CREATE SERVER' was added in MySQL 5.1.15.


File: manual.info,  Node: create-table,  Next: create-tablespace,  Prev: create-server,  Up: sql-syntax-data-definition

12.1.10 `CREATE TABLE' Syntax
-----------------------------

* Menu:

* silent-column-changes::        Silent Column Specification Changes

     CREATE [TEMPORARY] TABLE [IF NOT EXISTS] TBL_NAME
         (CREATE_DEFINITION,...)
         [TABLE_OPTION] ...
         [PARTITION_OPTIONS]

Or:

     CREATE [TEMPORARY] TABLE [IF NOT EXISTS] TBL_NAME
         [(CREATE_DEFINITION,...)]
         [TABLE_OPTION] ...
         [PARTITION_OPTIONS]
         SELECT_STATEMENT

Or:

     CREATE [TEMPORARY] TABLE [IF NOT EXISTS] TBL_NAME
         { LIKE OLD_TBL_NAME | (LIKE OLD_TBL_NAME) }

     CREATE_DEFINITION:
         COL_NAME COLUMN_DEFINITION
       | [CONSTRAINT [SYMBOL]] PRIMARY KEY [INDEX_TYPE] (INDEX_COL_NAME,...)
           [INDEX_OPTION] ...
       | {INDEX|KEY} [INDEX_NAME] [INDEX_TYPE] (INDEX_COL_NAME,...)
           [INDEX_OPTION] ...
       | [CONSTRAINT [SYMBOL]] UNIQUE [INDEX|KEY]
           [INDEX_NAME] [INDEX_TYPE] (INDEX_COL_NAME,...)
           [INDEX_OPTION] ...
       | {FULLTEXT|SPATIAL} [INDEX|KEY] [INDEX_NAME] (INDEX_COL_NAME,...)
           [INDEX_OPTION] ...
       | [CONSTRAINT [SYMBOL]] FOREIGN KEY
           [INDEX_NAME] (INDEX_COL_NAME,...) REFERENCE_DEFINITION
       | CHECK (EXPR)

     COLUMN_DEFINITION:
         DATA_TYPE [NOT NULL | NULL] [DEFAULT DEFAULT_VALUE]
           [AUTO_INCREMENT] [UNIQUE [KEY] | [PRIMARY] KEY]
           [COMMENT 'STRING'] [REFERENCE_DEFINITION]
           [COLUMN_FORMAT {FIXED|DYNAMIC|DEFAULT}]
           [STORAGE {DISK|MEMORY}]

     DATA_TYPE:
         BIT[(LENGTH)]
       | TINYINT[(LENGTH)] [UNSIGNED] [ZEROFILL]
       | SMALLINT[(LENGTH)] [UNSIGNED] [ZEROFILL]
       | MEDIUMINT[(LENGTH)] [UNSIGNED] [ZEROFILL]
       | INT[(LENGTH)] [UNSIGNED] [ZEROFILL]
       | INTEGER[(LENGTH)] [UNSIGNED] [ZEROFILL]
       | BIGINT[(LENGTH)] [UNSIGNED] [ZEROFILL]
       | REAL[(LENGTH,DECIMALS)] [UNSIGNED] [ZEROFILL]
       | DOUBLE[(LENGTH,DECIMALS)] [UNSIGNED] [ZEROFILL]
       | FLOAT[(LENGTH,DECIMALS)] [UNSIGNED] [ZEROFILL]
       | DECIMAL[(LENGTH[,DECIMALS])] [UNSIGNED] [ZEROFILL]
       | NUMERIC[(LENGTH[,DECIMALS])] [UNSIGNED] [ZEROFILL]
       | DATE
       | TIME
       | TIMESTAMP
       | DATETIME
       | YEAR
       | CHAR[(LENGTH)]
           [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]
       | VARCHAR(LENGTH)
           [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]
       | BINARY[(LENGTH)]
       | VARBINARY(LENGTH)
       | TINYBLOB
       | BLOB
       | MEDIUMBLOB
       | LONGBLOB
       | TINYTEXT [BINARY]
           [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]
       | TEXT [BINARY]
           [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]
       | MEDIUMTEXT [BINARY]
           [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]
       | LONGTEXT [BINARY]
           [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]
       | ENUM(VALUE1,VALUE2,VALUE3,...)
           [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]
       | SET(VALUE1,VALUE2,VALUE3,...)
           [CHARACTER SET CHARSET_NAME] [COLLATE COLLATION_NAME]
       | SPATIAL_TYPE

     INDEX_COL_NAME:
         COL_NAME [(LENGTH)] [ASC | DESC]

     INDEX_TYPE:
         USING {BTREE | HASH | RTREE}

     INDEX_OPTION:
         KEY_BLOCK_SIZE [=] VALUE
       | INDEX_TYPE
       | WITH PARSER PARSER_NAME

     REFERENCE_DEFINITION:
         REFERENCES TBL_NAME (INDEX_COL_NAME,...)
           [MATCH FULL | MATCH PARTIAL | MATCH SIMPLE]
           [ON DELETE REFERENCE_OPTION]
           [ON UPDATE REFERENCE_OPTION]

     REFERENCE_OPTION:
         RESTRICT | CASCADE | SET NULL | NO ACTION

     TABLE_OPTION:
         TABLESPACE TABLESPACE_NAME STORAGE DISK
         ENGINE [=] ENGINE_NAME
       | AUTO_INCREMENT [=] VALUE
       | AVG_ROW_LENGTH [=] VALUE
       | [DEFAULT] CHARACTER SET [=] CHARSET_NAME
       | CHECKSUM [=] {0 | 1}
       | [DEFAULT] COLLATE [=] COLLATION_NAME
       | COMMENT [=] 'STRING'
       | CONNECTION [=] 'CONNECT_STRING'
       | DATA DIRECTORY [=] 'ABSOLUTE PATH TO DIRECTORY'
       | DELAY_KEY_WRITE [=] {0 | 1}
       | INDEX DIRECTORY [=] 'ABSOLUTE PATH TO DIRECTORY'
       | INSERT_METHOD [=] { NO | FIRST | LAST }
       | KEY_BLOCK_SIZE [=] VALUE
       | MAX_ROWS [=] VALUE
       | MIN_ROWS [=] VALUE
       | PACK_KEYS [=] {0 | 1 | DEFAULT}
       | PASSWORD [=] 'STRING'
       | ROW_FORMAT [=] {DEFAULT|DYNAMIC|FIXED|COMPRESSED|REDUNDANT|COMPACT}
       | UNION [=] (TBL_NAME[,TBL_NAME]...)

     PARTITION_OPTIONS:
         PARTITION BY
             { [LINEAR] HASH(EXPR)
             | [LINEAR] KEY(COLUMN_LIST)
             | RANGE(EXPR)
             | LIST(EXPR) }
         [PARTITIONS NUM]
         [SUBPARTITION BY
             { [LINEAR] HASH(EXPR)
             | [LINEAR] KEY(COLUMN_LIST) }
           [SUBPARTITIONS NUM]
         ]
         [(PARTITION_DEFINITION [, PARTITION_DEFINITION] ...)]

     PARTITION_DEFINITION:
         PARTITION PARTITION_NAME
             [VALUES {LESS THAN {(EXPR) | `MAXVALUE'} | IN (VALUE_LIST)}]
             [[STORAGE] ENGINE [=] ENGINE_NAME]
             [COMMENT [=] 'COMMENT_TEXT' ]
             [DATA DIRECTORY [=] '`DATA_DIR'']
             [INDEX DIRECTORY [=] '`INDEX_DIR'']
             [MAX_ROWS [=] MAX_NUMBER_OF_ROWS]
             [MIN_ROWS [=] MIN_NUMBER_OF_ROWS]
             [TABLESPACE [=] TABLESPACE_NAME]
             [NODEGROUP [=] NODE_GROUP_ID]
             [(SUBPARTITION_DEFINITION [, SUBPARTITION_DEFINITION] ...)]

     SUBPARTITION_DEFINITION:
         SUBPARTITION LOGICAL_NAME
             [[STORAGE] ENGINE [=] ENGINE_NAME]
             [COMMENT [=] 'COMMENT_TEXT' ]
             [DATA DIRECTORY [=] '`DATA_DIR'']
             [INDEX DIRECTORY [=] '`INDEX_DIR'']
             [MAX_ROWS [=] MAX_NUMBER_OF_ROWS]
             [MIN_ROWS [=] MIN_NUMBER_OF_ROWS]
             [TABLESPACE [=] TABLESPACE_NAME]
             [NODEGROUP [=] NODE_GROUP_ID]

     SELECT_STATEMENT:
         [IGNORE | REPLACE] [AS] SELECT ...   (SOME LEGAL SELECT STATEMENT)

`CREATE TABLE' creates a table with the given name. You must have the
`CREATE' privilege for the table.

Rules for allowable table names are given in *Note identifiers::. By
default, the table is created in the default database. An error occurs
if the table exists, if there is no default database, or if the
database does not exist.

The table name can be specified as DB_NAME.TBL_NAME to create the table
in a specific database. This works regardless of whether there is a
default database, assuming that the database exists. If you use quoted
identifiers, quote the database and table names separately.  For
example, write ``mydb`.`mytbl`', not ``mydb.mytbl`'.

You can use the `TEMPORARY' keyword when creating a table. A
`TEMPORARY' table is visible only to the current connection, and is
dropped automatically when the connection is closed. This means that
two different connections can use the same temporary table name without
conflicting with each other or with an existing non-`TEMPORARY' table
of the same name. (The existing table is hidden until the temporary
table is dropped.) To create temporary tables, you must have the
`CREATE TEMPORARY TABLES' privilege.

*Note*:

`CREATE TABLE' does not automatically commit the current active
transaction if you use the `TEMPORARY' keyword.

The keywords `IF NOT EXISTS' prevent an error from occurring if the
table exists. However, there is no verification that the existing table
has a structure identical to that indicated by the `CREATE TABLE'
statement.

*Note*:

If you use `IF NOT EXISTS' in a `CREATE TABLE ... SELECT' statement,
any rows selected by the `SELECT' part are inserted regardless of
whether the table already exists.

MySQL represents each table by an `.frm' table format (definition) file
in the database directory. The storage engine for the table might
create other files as well. In the case of `MyISAM' tables, the storage
engine creates data and index files. Thus, for each `MyISAM' table
TBL_NAME, there are three disk files:

*File*                 *Purpose*
`TBL_NAME.frm'         Table format (definition) file
`TBL_NAME.MYD'         Data file
`TBL_NAME.MYI'         Index file

*Note storage-engines::, describes what files each storage engine
creates to represent tables. If a table name contains special
characters, the names for the table files contain encoded versions of
those characters as described in *Note identifier-mapping::.

DATA_TYPE represents the data type in a column definition. SPATIAL_TYPE
represents a spatial data type. The data type syntax shown is
representative only. For a full description of the syntax available for
specifying column data types, as well as information about the
properties of each type, see *Note data-types::, and *Note
spatial-extensions::.

Some attributes do not apply to all data types.  `AUTO_INCREMENT'
applies only to integer and floating-point types. `DEFAULT' does not
apply to the `BLOB' or `TEXT' types.

   * If neither `NULL' nor `NOT NULL' is specified, the column is
     treated as though `NULL' had been specified.

   * An integer or floating-point column can have the additional
     attribute `AUTO_INCREMENT'. When you insert a value of `NULL'
     (recommended) or `0' into an indexed `AUTO_INCREMENT' column, the
     column is set to the next sequence value. Typically this is
     `VALUE+1', where VALUE is the largest value for the column
     currently in the table.  `AUTO_INCREMENT' sequences begin with `1'.

     To retrieve an `AUTO_INCREMENT' value after inserting a row, use
     the `LAST_INSERT_ID()' SQL function or the *Note
     `mysql_insert_id()': mysql-insert-id. C API function. See *Note
     information-functions::, and *Note mysql-insert-id::.

     If the `NO_AUTO_VALUE_ON_ZERO' SQL mode is enabled, you can store
     `0' in `AUTO_INCREMENT' columns as `0' without generating a new
     sequence value.  See *Note server-sql-mode::.

     *Note*:

     There can be only one `AUTO_INCREMENT' column per table, it must
     be indexed, and it cannot have a `DEFAULT' value. An
     `AUTO_INCREMENT' column works properly only if it contains only
     positive values. Inserting a negative number is regarded as
     inserting a very large positive number. This is done to avoid
     precision problems when numbers `wrap' over from positive to
     negative and also to ensure that you do not accidentally get an
     `AUTO_INCREMENT' column that contains `0'.

     For `MyISAM' tables, you can specify an `AUTO_INCREMENT' secondary
     column in a multiple-column key. See *Note
     example-auto-increment::.

     To make MySQL compatible with some ODBC applications, you can find
     the `AUTO_INCREMENT' value for the last inserted row with the
     following query:

          SELECT * FROM TBL_NAME WHERE AUTO_COL IS NULL

     For information about `InnoDB' and `AUTO_INCREMENT', see *Note
     innodb-auto-increment-handling::.

   * Character data types (`CHAR', `VARCHAR', `TEXT') can include
     `CHARACTER SET' and `COLLATE' attributes to specify the character
     set and collation for the column. For details, see *Note
     charset::. `CHARSET' is a synonym for `CHARACTER SET'. Example:

          CREATE TABLE t (c CHAR(20) CHARACTER SET utf8 COLLATE utf8_bin);

     MySQL 5.1 interprets length specifications in character column
     definitions in characters. (Versions before MySQL 4.1 interpreted
     them in bytes.) Lengths for `BINARY' and `VARBINARY' are in bytes.

   * The `DEFAULT' clause specifies a default value for a column. With
     one exception, the default value must be a constant; it cannot be
     a function or an expression. This means, for example, that you
     cannot set the default for a date column to be the value of a
     function such as `NOW()' or `CURRENT_DATE'. The exception is that
     you can specify `CURRENT_TIMESTAMP' as the default for a
     `TIMESTAMP' column. See *Note timestamp::.

     If a column definition includes no explicit `DEFAULT' value, MySQL
     determines the default value as described in *Note
     data-type-defaults::.

     `BLOB' and `TEXT' columns cannot be assigned a default value.

     `CREATE TABLE' fails if a date-valued default is not correct
     according to the `NO_ZERO_IN_DATE' SQL mode, even if strict SQL
     mode is not enabled. For example, `c1 DATE DEFAULT '2010-00-00''
     causes `CREATE TABLE' to fail with `Invalid default value for
     'c1''.

   * A comment for a column can be specified with the `COMMENT' option,
     up to 255 characters long.  The comment is displayed by the `SHOW
     CREATE TABLE' and `SHOW FULL COLUMNS' statements.

   * Beginning with MySQL Cluster NDB 6.2.5 and MySQL Cluster NDB
     6.3.2, it is also possible to specify a data storage format for
     individual columns of `NDB' tables using `COLUMN_FORMAT'.
     Allowable column formats are `FIXED', `DYNAMIC', and `DEFAULT'.
     `FIXED' is used to specify fixed-width storage, `DYNAMIC' allows
     the column to be variable-width, and `DEFAULT' causes the column
     to use fixed-width or variable-width storage as determined by the
     column's data type (possibly overridden by a `ROW_FORMAT'
     specifier).

     For `NDB' tables, the default value for `COLUMN_FORMAT' is
     `DEFAULT'.

     `COLUMN_FORMAT' currently has no effect on columns of tables using
     storage engines other than `NDB'.

   * For `NDB' tables, beginning with MySQL Cluster NDB 6.2.5 and MySQL
     Cluster NDB 6.3.2, it is also possible to specify whether the
     column is stored on disk or in memory by using a `STORAGE' clause.
     `STORAGE DISK' causes the column to be stored on disk, and
     `STORAGE MEMORY' causes in-memory storage to be used.

     For `NDB' tables, the default is `MEMORY'.

     The `STORAGE' clause has no effect on tables using storage engines
     other than `NDB'.

   * `KEY' is normally a synonym for `INDEX'. The key attribute `PRIMARY
     KEY' can also be specified as just `KEY' when given in a column
     definition. This was implemented for compatibility with other
     database systems.

   * A `UNIQUE' index creates a constraint such that all values in the
     index must be distinct. An error occurs if you try to add a new
     row with a key value that matches an existing row. For all
     engines, a `UNIQUE' index allows multiple `NULL' values for
     columns that can contain `NULL'.

   * A `PRIMARY KEY' is a unique index where all key columns must be
     defined as `NOT NULL'. If they are not explicitly declared as `NOT
     NULL', MySQL declares them so implicitly (and silently). A table
     can have only one `PRIMARY KEY'. If you do not have a `PRIMARY
     KEY' and an application asks for the `PRIMARY KEY' in your tables,
     MySQL returns the first `UNIQUE' index that has no `NULL' columns
     as the `PRIMARY KEY'.

     In `InnoDB' tables, having a long `PRIMARY KEY' wastes a lot of
     space. (See *Note innodb-table-and-index::.)

   * In the created table, a `PRIMARY KEY' is placed first, followed by
     all `UNIQUE' indexes, and then the non-unique indexes. This helps
     the MySQL optimizer to prioritize which index to use and also more
     quickly to detect duplicated `UNIQUE' keys.

   * A `PRIMARY KEY' can be a multiple-column index. However, you
     cannot create a multiple-column index using the `PRIMARY KEY' key
     attribute in a column specification. Doing so only marks that
     single column as primary. You must use a separate `PRIMARY
     KEY(INDEX_COL_NAME, ...)' clause.

   * If a `PRIMARY KEY' or `UNIQUE' index consists of only one column
     that has an integer type, you can also refer to the column as
     `_rowid' in `SELECT' statements.

   * In MySQL, the name of a `PRIMARY KEY' is `PRIMARY'. For other
     indexes, if you do not assign a name, the index is assigned the
     same name as the first indexed column, with an optional suffix
     (`_2', `_3', `...') to make it unique. You can see index names for
     a table using `SHOW INDEX FROM TBL_NAME'. See *Note show-index::.

   * Some storage engines allow you to specify an index type when
     creating an index. The syntax for the INDEX_TYPE specifier is
     `USING TYPE_NAME'.

     Example:

          CREATE TABLE lookup
            (id INT, INDEX USING BTREE (id))
            ENGINE = MEMORY;

     Before MySQL 5.1.10, `USING' can be given only before the index
     column list. As of 5.1.10, the preferred position is after the
     column list. Use of the option before the column list will no
     longer be recognized as of MySQL 5.3.

     INDEX_OPTION values specify additional options for an index.
     `USING' is one such option. For details about allowable
     INDEX_OPTION values, see *Note create-index::.

     For more information about indexes, see *Note mysql-indexes::.

   * In MySQL 5.1, only the `MyISAM', `InnoDB', and `MEMORY' storage
     engines support indexes on columns that can have `NULL' values. In
     other cases, you must declare indexed columns as `NOT NULL' or an
     error results.

   * For `CHAR', `VARCHAR', `BINARY', and `VARBINARY' columns, indexes
     can be created that use only the leading part of column values,
     using `COL_NAME(LENGTH)' syntax to specify an index prefix length.
     `BLOB' and `TEXT' columns also can be indexed, but a prefix length
     _must_ be given. Prefix lengths are given in characters for
     non-binary string types and in bytes for binary string types. That
     is, index entries consist of the first LENGTH characters of each
     column value for `CHAR', `VARCHAR', and `TEXT' columns, and the
     first LENGTH bytes of each column value for `BINARY', `VARBINARY',
     and `BLOB' columns. Indexing only a prefix of column values like
     this can make the index file much smaller. See *Note indexes::.

     Only the `MyISAM' and `InnoDB' storage engines support indexing on
     `BLOB' and `TEXT' columns.  For example:

          CREATE TABLE test (blob_col BLOB, INDEX(blob_col(10)));

     Prefixes can be up to 1000 bytes long (767 bytes for `InnoDB'
     tables). Note that prefix limits are measured in bytes, whereas
     the prefix length in `CREATE TABLE' statements is interpreted as
     number of characters for non-binary data types (`CHAR', `VARCHAR',
     `TEXT'). Take this into account when specifying a prefix length
     for a column that uses a multi-byte character set.

   * An INDEX_COL_NAME specification can end with `ASC' or `DESC'.
     These keywords are allowed for future extensions for specifying
     ascending or descending index value storage.  Currently, they are
     parsed but ignored; index values are always stored in ascending
     order.

   * When you use `ORDER BY' or `GROUP BY' on a `TEXT' or `BLOB' column
     in a `SELECT', the server sorts values using only the initial
     number of bytes indicated by the `max_sort_length' system
     variable. See *Note blob::.

   * You can create special `FULLTEXT' indexes, which are used for
     full-text searches. Only the `MyISAM' storage engine supports
     `FULLTEXT' indexes. They can be created only from `CHAR',
     `VARCHAR', and `TEXT' columns. Indexing always happens over the
     entire column; column prefix indexing is not supported and any
     prefix length is ignored if specified. See *Note
     fulltext-search::, for details of operation. A `WITH PARSER'
     clause can be specified as an INDEX_OPTION value to associate a
     parser plugin with the index if full-text indexing and searching
     operations need special handling. This clause is legal only for
     `FULLTEXT' indexes. See *Note plugin-api::, for details on
     creating plugins.

   * You can create `SPATIAL' indexes on spatial data types. Spatial
     types are supported only for `MyISAM' tables and indexed columns
     must be declared as `NOT NULL'. See *Note spatial-extensions::.

   * `InnoDB' tables support checking of foreign key constraints. See
     *Note innodb::. Note that the `FOREIGN KEY' syntax in `InnoDB' is
     more restrictive than the syntax presented for the `CREATE TABLE'
     statement at the beginning of this section: The columns of the
     referenced table must always be explicitly named.  `InnoDB'
     supports both `ON DELETE' and `ON UPDATE' actions on foreign keys.
     For the precise syntax, see *Note innodb-foreign-key-constraints::.

     For other storage engines, MySQL Server parses and ignores the
     `FOREIGN KEY' and `REFERENCES' syntax in `CREATE TABLE'
     statements. The `CHECK' clause is parsed but ignored by all
     storage engines. See *Note ansi-diff-foreign-keys::.

     *Important*:

     For users familiar with the ANSI/ISO SQL Standard, please note
     that no storage engine, including `InnoDB', recognizes or enforces
     the `MATCH' clause used in referential integrity constraint
     definitions. Use of an explicit `MATCH' clause will not have the
     specified effect, and also causes `ON DELETE' and `ON UPDATE'
     clauses to be ignored. For these reasons, specifying `MATCH'
     should be avoided.

     The `MATCH' clause in the SQL standard controls how `NULL' values
     in a composite (multiple-column) foreign key are handled when
     comparing to a primary key. `InnoDB' essentially implements the
     semantics defined by `MATCH SIMPLE', which allow a foreign key to
     be all or partially `NULL'. In that case, the (child table) row
     containing such a foreign key is allowed to be inserted, and does
     not match any row in the referenced (parent) table. It is possible
     to implement other semantics using triggers.

     Additionally, MySQL and `InnoDB' require that the referenced
     columns be indexed for performance.  However, the system does not
     enforce a requirement that the referenced columns be `UNIQUE' or be
     declared `NOT NULL'. The handling of foreign key references to
     non-unique keys or keys that contain `NULL' values is not well
     defined for operations such as `UPDATE' or `DELETE CASCADE'. You
     are advised to use foreign keys that reference only `UNIQUE' and
     `NOT NULL' keys.

     Furthermore, `InnoDB' does not recognize or support `inline
     `REFERENCES' specifications' (as defined in the SQL standard)
     where the references are defined as part of the column
     specification. `InnoDB' accepts `REFERENCES' clauses only when
     specified as part of a separate `FOREIGN KEY' specification. For
     other storage engines, MySQL Server parses and ignores foreign key
     specifications.

     *Note*:

     Partitioned tables do not support foreign keys. See *Note
     partitioning-limitations::, for more information.

   * There is a hard limit of 4096 columns per table, but the effective
     maximum may be less for a given table and depends on the factors
     discussed in *Note column-count-limit::.

The `TABLESPACE ... STORAGE DISK' table option is used only with
`NDBCLUSTER' tables. It assigns the table to a Cluster Disk Data
tablespace. The tablespace named TABLESPACE_NAME must already have been
created using `CREATE TABLESPACE'. This table option was introduced in
MySQL 5.1.6. See *Note mysql-cluster-disk-data::.

The `ENGINE' table option specifies the storage engine for the table.

The `ENGINE' table option takes the storage engine names shown in the
following table.

*Storage Engine*   *Description*
`ARCHIVE'          The archiving storage engine. See *Note
                   archive-storage-engine::.
`CSV'              Tables that store rows in comma-separated values
                   format. See *Note csv-storage-engine::.
`EXAMPLE'          An example engine. See *Note
                   example-storage-engine::.
`FEDERATED'        Storage engine that accesses remote tables. See
                   *Note federated-storage-engine::.
`HEAP'             This is a synonym for `MEMORY'.
`ISAM'             Not available in MySQL 5.1. If you are upgrading
(_OBSOLETE_)       to MySQL 5.1 from a previous version, you should
                   convert any existing `ISAM' tables to `MyISAM'
                   _before_ performing the upgrade.
`InnoDB'           Transaction-safe tables with row locking and
                   foreign keys. See *Note innodb::.
`MEMORY'           The data for this storage engine is stored only
                   in memory. See *Note memory-storage-engine::.
`MERGE'            A collection of `MyISAM' tables used as one
                   table. Also known as `MRG_MyISAM'. See *Note
                   merge-storage-engine::.
`MyISAM'           The binary portable storage engine that is the
                   default storage engine used by MySQL. See *Note
                   myisam-storage-engine::.
`NDBCLUSTER'       Clustered, fault-tolerant, memory-based tables.
                   Also known as `NDB'. See *Note mysql-cluster::.

If a storage engine is specified that is not available, MySQL uses the
default engine instead. Normally, this is `MyISAM'. For example, if a
table definition includes the `ENGINE=INNODB' option but the MySQL
server does not support `INNODB' tables, the table is created as a
`MyISAM' table. This makes it possible to have a replication setup
where you have transactional tables on the master but tables created on
the slave are non-transactional (to get more speed). In MySQL 5.1, a
warning occurs if the storage engine specification is not honored.

Engine substitution can be controlled by the setting of the
`NO_ENGINE_SUBSTITUTION' SQL mode, as described in *Note
server-sql-mode::.

*Note*:

The older `TYPE' option was synonymous with `ENGINE'. `TYPE' has been
deprecated since MySQL 4.0 but is still supported for backward
compatibility in MySQL 5.1 (excepting MySQL 5.1.7). Since MySQL 5.1.8,
it produces a warning. It is removed as of MySQL 5.2.  _You should not
use `TYPE' in any new applications, and you should immediately begin
conversion of existing applications to use `ENGINE' instead_. (See
*Note news-5-1-8::.)

The other table options are used to optimize the behavior of the table.
In most cases, you do not have to specify any of them.  These options
apply to all storage engines unless otherwise indicated. Options that
do not apply to a given storage engine may be accepted and remembered
as part of the table definition. Such options then apply if you later
use `ALTER TABLE' to convert the table to use a different storage
engine.

   * `AUTO_INCREMENT'

     The initial `AUTO_INCREMENT' value for the table. In MySQL 5.1,
     this works for `MyISAM', `MEMORY', and `InnoDB' tables. It also
     works for `ARCHIVE' tables as of MySQL 5.1.6. To set the first
     auto-increment value for engines that do not support the
     `AUTO_INCREMENT' table option, insert a `dummy' row with a value
     one less than the desired value after creating the table, and then
     delete the dummy row.

     For engines that support the `AUTO_INCREMENT' table option in
     `CREATE TABLE' statements, you can also use `ALTER TABLE TBL_NAME
     AUTO_INCREMENT = N' to reset the `AUTO_INCREMENT' value. The value
     cannot be set lower than the maximum value currently in the column.

   * `AVG_ROW_LENGTH'

     An approximation of the average row length for your table. You
     need to set this only for large tables with variable-size rows.

     When you create a `MyISAM' table, MySQL uses the product of the
     `MAX_ROWS' and `AVG_ROW_LENGTH' options to decide how big the
     resulting table is. If you don't specify either option, the
     maximum size for `MyISAM' data and index files is 256TB by
     default. (If your operating system does not support files that
     large, table sizes are constrained by the file size limit.) If you
     want to keep down the pointer sizes to make the index smaller and
     faster and you don't really need big files, you can decrease the
     default pointer size by setting the `myisam_data_pointer_size'
     system variable. (See *Note server-system-variables::.) If you
     want all your tables to be able to grow above the default limit
     and are willing to have your tables slightly slower and larger
     than necessary, you can increase the default pointer size by
     setting this variable. Setting the value to 7 allows table sizes
     up to 65,536TB.

   * `[DEFAULT] CHARACTER SET'

     Specify a default character set for the table.  `CHARSET' is a
     synonym for `CHARACTER SET'. If the character set name is
     `DEFAULT', the database character set is used.

   * `CHECKSUM'

     Set this to 1 if you want MySQL to maintain a live checksum for
     all rows (that is, a checksum that MySQL updates automatically as
     the table changes). This makes the table a little slower to
     update, but also makes it easier to find corrupted tables. The
     `CHECKSUM TABLE' statement reports the checksum. (`MyISAM' only.)

   * `[DEFAULT] COLLATE'

     Specify a default collation for the table.

   * `COMMENT'

     A comment for the table, up to 60 characters long.

   * `CONNECTION'

     The connection string for a `FEDERATED' table.

     *Note*:

     Older versions of MySQL used a `COMMENT' option for the connection
     string.

   * `DATA DIRECTORY', `INDEX DIRECTORY'

     By using `DATA DIRECTORY='DIRECTORY'' or `INDEX
     DIRECTORY='DIRECTORY'' you can specify where the `MyISAM' storage
     engine should put a table's data file and index file. The directory
     must be the full pathname to the directory, not a relative path.

     *Important*:

     Beginning with MySQL 5.1.23, table-level `DATA DIRECTORY' and
     `INDEX DIRECTORY' options are ignored for partitioned tables.
     (Bug#32091 (http://bugs.mysql.com/32091))

     These options work only when you are not using the
     `--skip-symbolic-links' option. Your operating system must also
     have a working, thread-safe `realpath()' call. See *Note
     symbolic-links-to-tables::, for more complete information.

     If a `MyISAM' table is created with no `DATA DIRECTORY' option, the
     `.MYD' file is created in the database directory. By default, if
     `MyISAM' finds an existing `.MYD' file in this case, it overwrites
     it. The same applies to `.MYI' files for tables created with no
     `INDEX DIRECTORY' option. As of MySQL 5.1.23, to suppress this
     behavior, start the server with the `--keep_files_on_create'
     option, in which case `MyISAM' will not overwrite existing files
     and returns an error instead.

     If a `MyISAM' table is created with a `DATA DIRECTORY' or `INDEX
     DIRECTORY' option and an existing `.MYD' or `.MYI' file is found,
     MyISAM always returns an error. It will not overwrite a file in
     the specified directory.

     *Important*:

     Beginning with MySQL 5.1.24, you cannot use pathnames that contain
     the MySQL data directory with `DATA DIRECTORY' or `INDEX
     DIRECTORY'.  This includes partitioned tables and individual table
     partitions. (See Bug#32167 (http://bugs.mysql.com/32167).)

   * `DELAY_KEY_WRITE'

     Set this to 1 if you want to delay key updates for the table until
     the table is closed. See the description of the `delay_key_write'
     system variable in *Note server-system-variables::.  (`MyISAM'
     only.)

   * `INSERT_METHOD'

     If you want to insert data into a `MERGE' table, you must specify
     with `INSERT_METHOD' the table into which the row should be
     inserted.  `INSERT_METHOD' is an option useful for `MERGE' tables
     only. Use a value of `FIRST' or `LAST' to have inserts go to the
     first or last table, or a value of `NO' to prevent inserts. See
     *Note merge-storage-engine::.

   * `KEY_BLOCK_SIZE'

     This option provides a hint to the storage engine about the size
     in bytes to use for index key blocks. The engine is allowed to
     change the value if necessary. A value of 0 indicates that the
     default value should be used. Individual index definitions can
     specify a `KEY_BLOCK_SIZE' value of their own to override the
     table value. `KEY_BLOCK_SIZE' was added in MySQL 5.1.10.

   * `MAX_ROWS'

     The maximum number of rows you plan to store in the table.  This
     is not a hard limit, but rather a hint to the storage engine that
     the table must be able to store at least this many rows.

   * `MIN_ROWS'

     The minimum number of rows you plan to store in the table.

   * `PACK_KEYS'

     `PACK_KEYS' takes effect only with `MyISAM' tables. Set this
     option to 1 if you want to have smaller indexes. This usually
     makes updates slower and reads faster. Setting the option to 0
     disables all packing of keys. Setting it to `DEFAULT' tells the
     storage engine to pack only long `CHAR', `VARCHAR', `BINARY', or
     `VARBINARY' columns.

     If you do not use `PACK_KEYS', the default is to pack strings, but
     not numbers. If you use `PACK_KEYS=1', numbers are packed as well.

     When packing binary number keys, MySQL uses prefix compression:

        * Every key needs one extra byte to indicate how many bytes of
          the previous key are the same for the next key.

        * The pointer to the row is stored in high-byte-first order
          directly after the key, to improve compression.

     This means that if you have many equal keys on two consecutive
     rows, all following `same' keys usually only take two bytes
     (including the pointer to the row). Compare this to the ordinary
     case where the following keys takes `storage_size_for_key +
     pointer_size' (where the pointer size is usually 4). Conversely,
     you get a significant benefit from prefix compression only if you
     have many numbers that are the same. If all keys are totally
     different, you use one byte more per key, if the key is not a key
     that can have `NULL' values. (In this case, the packed key length
     is stored in the same byte that is used to mark if a key is
     `NULL'.)

   * `PASSWORD'

     This option is unused. If you have a need to scramble your `.frm'
     files and make them unusable to any other MySQL server, please
     contact our sales department.

   * `RAID_TYPE'

     `RAID' support has been removed as of MySQL 5.0. For information
     on `RAID', see `/4.1/en/create-table.html'.

   * `ROW_FORMAT'

     Defines how the rows should be stored. For `MyISAM' tables, the
     option value can be `FIXED' or `DYNAMIC' for static or
     variable-length row format.  `myisampack' sets the type to
     `COMPRESSED'. See *Note myisam-table-formats::.

     For `InnoDB' tables, rows are stored in compact format
     (`ROW_FORMAT=COMPACT') by default. The non-compact format used in
     older versions of MySQL can still be requested by specifying
     `ROW_FORMAT=REDUNDANT'.

     *Note*:

     During `CREATE TABLE', if you specify a row format that the engine
     does support, the table will be created using the storage engines
     default row format. The information reported in this column in
     response to `SHOW TABLE STATUS' is the actual row format used.
     This may differ from the value in the `Create_options' column
     because the original `CREATE TABLE' definition is retained during
     creation.

   * `UNION'

     `UNION' is used when you want to access a collection of identical
     `MyISAM' tables as one. This works only with `MERGE' tables. See
     *Note merge-storage-engine::.

     You must have `SELECT', `UPDATE', and `DELETE' privileges for the
     tables you map to a `MERGE' table.

     *Note*:

     Formerly, all tables used had to be in the same database as the
     `MERGE' table itself. This restriction no longer applies.

PARTITION_OPTIONS can be used to control partitioning of the table
created with `CREATE TABLE'.

*Important*:

Not all options shown in the syntax for PARTITION_OPTIONS at the
beginning of this section are available for all partitioning types.
Please see the listings for the following individual types for
information specific to each type, and see *Note partitioning::, for
more complete information about the workings of and uses for
partitioning in MySQL, as well as additional examples of table creation
and other statements relating to MySQL partitioning.

If used, a PARTITION_OPTIONS clause begins with `PARTITION BY'. This
clause contains the function that is used to determine the partition;
the function returns an integer value ranging from 1 to NUM, where NUM
is the number of partitions. (The maximum number of user-defined
partitions which a table may contain is 1024; the number of
subpartitions -- discussed later in this section -- is included in this
maximum.) The choices that are available for this function in MySQL 5.1
are shown in the following list:

   * `HASH(EXPR)': Hashes one or more columns to create a key for
     placing and locating rows. EXPR is an expression using one or more
     table columns. This can be any legal MySQL expression (including
     MySQL functions) that yields a single integer value. For example,
     these are all valid `CREATE TABLE' statements using `PARTITION BY
     HASH':

          CREATE TABLE t1 (col1 INT, col2 CHAR(5))
              PARTITION BY HASH(col1);

          CREATE TABLE t1 (col1 INT, col2 CHAR(5))
              PARTITION BY HASH( ORD(col2) );

          CREATE TABLE t1 (col1 INT, col2 CHAR(5), col3 DATETIME)
              PARTITION BY HASH ( YEAR(col3) );

     You may not use either `VALUES LESS THAN' or `VALUES IN' clauses
     with `PARTITION BY HASH'.

     `PARTITION BY HASH' uses the remainder of EXPR divided by the
     number of partitions (that is, the modulus). For examples and
     additional information, see *Note partitioning-hash::.

     The `LINEAR' keyword entails a somewhat different algorithm. In
     this case, the number of the partition in which a row is stored is
     calculated as the result of one or more logical `AND' operations.
     For discussion and examples of linear hashing, see *Note
     partitioning-linear-hash::.

   * `KEY(COLUMN_LIST)': This is similar to `HASH', except that MySQL
     supplies the hashing function so as to guarantee an even data
     distribution. The COLUMN_LIST argument is simply a list of table
     columns. This example shows a simple table partitioned by key,
     with 4 partitions:

          CREATE TABLE tk (col1 INT, col2 CHAR(5), col3 DATE)
              PARTITION BY KEY(col3)
              PARTITIONS 4;

     For tables that are partitioned by key, you can employ linear
     partitioning by using the `LINEAR' keyword.  This has the same
     effect as with tables that are partitioned by `HASH'. That is, the
     partition number is found using the `&' operator rather than the
     modulus (see *Note partitioning-linear-hash::, and *Note
     partitioning-key::, for details). This example uses linear
     partitioning by key to distribute data between 5 partitions:

          CREATE TABLE tk (col1 INT, col2 CHAR(5), col3 DATE)
              PARTITION BY LINEAR KEY(col3)
              PARTITIONS 5;

     You may not use either `VALUES LESS THAN' or `VALUES IN' clauses
     with `PARTITION BY KEY'.

   * `RANGE': In this case, EXPR shows a range of values using a set of
     `VALUES LESS THAN' operators. When using range partitioning, you
     must define at least one partition using `VALUES LESS THAN'. You
     cannot use `VALUES IN' with range partitioning.

     `VALUES LESS THAN' can be used with either a literal value or an
     expression that evaluates to a single value.

     Suppose that you have a table that you wish to partition on a
     column containing year values, according to the following scheme:

     *Partition Number*:         *Years Range*:
     0                           1990 and earlier
     1                           1991 - 1994
     2                           1995 - 1998
     3                           1999 - 2002
     4                           2003 - 2005
     5                           2006 and later

     A table implementing such a partitioning scheme can be realized by
     the `CREATE TABLE' statement shown here:

          CREATE TABLE t1 (
              year_col  INT,
              some_data INT
          )
          PARTITION BY RANGE (year_col) (
              PARTITION p0 VALUES LESS THAN (1991),
              PARTITION p1 VALUES LESS THAN (1995),
              PARTITION p2 VALUES LESS THAN (1999),
              PARTITION p3 VALUES LESS THAN (2002),
              PARTITION p4 VALUES LESS THAN (2006),
              PARTITION p5 VALUES LESS THAN MAXVALUE
          );

     `PARTITION ... VALUES LESS THAN ...' statements work in a
     consecutive fashion. `VALUES LESS THAN MAXVALUE' works to specify
     `leftover' values that are greater than the maximum value
     otherwise specified.

     Note that `VALUES LESS THAN' clauses work sequentially in a manner
     similar to that of the `case' portions of a `switch ...  case'
     block (as found in many programming languages such as C, Java, and
     PHP). That is, the clauses must be arranged in such a way that the
     upper limit specified in each successive `VALUES LESS THAN' is
     greater than that of the previous one, with the one referencing
     `MAXVALUE' coming last of all in the list.

   * `LIST(EXPR)': This is useful when assigning partitions based on a
     table column with a restricted set of possible values, such as a
     state or country code. In such a case, all rows pertaining to a
     certain state or country can be assigned to a single partition, or
     a partition can be reserved for a certain set of states or
     countries. It is similar to `RANGE', except that only `VALUES IN'
     may be used to specify allowable values for each partition.

     `VALUES IN' is used with a list of values to be matched. For
     instance, you could create a partitioning scheme such as the
     following:

          CREATE TABLE client_firms (
              id   INT,
              name VARCHAR(35)
          )
          PARTITION BY LIST (id) (
              PARTITION r0 VALUES IN (1, 5, 9, 13, 17, 21),
              PARTITION r1 VALUES IN (2, 6, 10, 14, 18, 22),
              PARTITION r2 VALUES IN (3, 7, 11, 15, 19, 23),
              PARTITION r3 VALUES IN (4, 8, 12, 16, 20, 24)
          );

     When using list partitioning, you must define at least one
     partition using `VALUES IN'. You cannot use `VALUES LESS THAN'
     with `PARTITION BY LIST'.

     *Note*:

     Currently, the value list used with `VALUES IN' must consist of
     integer values only.

   * The number of partitions may optionally be specified with a
     `PARTITIONS NUM' clause, where NUM is the number of partitions. If
     both this clause _and_ any `PARTITION' clauses are used, NUM must
     be equal to the total number of any partitions that are declared
     using `PARTITION' clauses.

     *Note*:

     Whether or not you use a `PARTITIONS' clause in creating a table
     that is partitioned by `RANGE' or `LIST', you must still include
     at least one `PARTITION VALUES' clause in the table definition
     (see below).

   * A partition may optionally be divided into a number of
     subpartitions. This can be indicated by using the optional
     `SUBPARTITION BY' clause. Subpartitioning may be done by `HASH' or
     `KEY'.  Either of these may be `LINEAR'. These work in the same
     way as previously described for the equivalent partitioning types.
     (It is not possible to subpartition by `LIST' or `RANGE'.)

     The number of subpartitions can be indicated using the
     `SUBPARTITIONS' keyword followed by an integer value.

   * MySQL 5.1.12 introduces rigorous checking of the value used in a
     `PARTITIONS' or `SUBPARTITIONS' clause. Beginning with this
     version, this value must adhere to the following rules:

        * The value must be a positive, non-zero integer.

        * No leading zeroes are permitted.

        * The value must be an integer literal, and cannot not be an
          expression. For example, `PARTITIONS 0.2E+01' is not allowed,
          even though `0.2E+01' evaluates to `2'. (Bug#15890
          (http://bugs.mysql.com/15890))

*Note*:

The expression (EXPR) used in a `PARTITION BY' clause cannot refer to
any columns not in the table being created; beginning with MySQL
5.1.23, such references are specifically disallowed and cause the
statement to fail with an error. (Bug#29444
(http://bugs.mysql.com/29444))

Each partition may be individually defined using a PARTITION_DEFINITION
clause. The individual parts making up this clause are as follows:

   * `PARTITION PARTITION_NAME': This specifies a logical name for the
     partition.

   * A `VALUES' clause: For range partitioning, each partition must
     include a `VALUES LESS THAN' clause; for list partitioning, you
     must specify a `VALUES IN' clause for each partition. This is used
     to determine which rows are to be stored in this partition. See
     the discussions of partitioning types in *Note partitioning::, for
     syntax examples.

   * An optional `COMMENT' clause may be used to specify a string that
     describes the partition. Example:

          COMMENT = 'Data for the years previous to 1999'

   * `DATA DIRECTORY' and `INDEX DIRECTORY' may be used to indicate the
     directory where, respectively, the data and indexes for this
     partition are to be stored. Both the `DATA_DIR' and the `INDEX_DIR'
     must be absolute system pathnames. Example:

          CREATE TABLE th (id INT, name VARCHAR(30), adate DATE)
          PARTITION BY LIST(YEAR(adate))
          (
            PARTITION p1999 VALUES IN (1995, 1999, 2003)
              DATA DIRECTORY = '`/var/appdata/95/data''
              INDEX DIRECTORY = '`/var/appdata/95/idx'',
            PARTITION p2000 VALUES IN (1996, 2000, 2004)
              DATA DIRECTORY = '`/var/appdata/96/data''
              INDEX DIRECTORY = '`/var/appdata/96/idx'',
            PARTITION p2001 VALUES IN (1997, 2001, 2005)
              DATA DIRECTORY = '`/var/appdata/97/data''
              INDEX DIRECTORY = '`/var/appdata/97/idx'',
            PARTITION p2000 VALUES IN (1998, 2002, 2006)
              DATA DIRECTORY = '`/var/appdata/98/data''
              INDEX DIRECTORY = '`/var/appdata/98/idx''
          );

     `DATA DIRECTORY' and `INDEX DIRECTORY' behave in the same way as
     in the `CREATE TABLE' statement's TABLE_OPTION clause as used for
     `MyISAM' tables.

     One data directory and one index directory may be specified per
     partition. If left unspecified, the data and indexes are stored by
     default in the table's database directory.

     On Windows, the `DATA DIRECTORY' and `INDEX DIRECTORY' options are
     not supported for individual partitions or subpartitions.
     Beginning with MySQL 5.1.24, these options are ignored on Windows,
     except that a warning is generated. (Bug#30459
     (http://bugs.mysql.com/30459))

     *Note*:

     Prior to MySQL 5.1.18, `DATA DIRECTORY' and `INDEX DIRECTORY' were
     allowed even if the `NO_DIR_IN_CREATE' server SQL mode was in
     effect at the time that a partitioned table was created.
     Beginning with MySQL 5.1.18, these options are ignored for
     creating partitioned tables if `NO_DIR_IN_CREATE' is in effect.
     (Bug#24633 (http://bugs.mysql.com/24633))

   * `MAX_ROWS' and `MIN_ROWS' may be used to specify, respectively,
     the maximum and minimum number of rows to be stored in the
     partition. The values for MAX_NUMBER_OF_ROWS and
     MIN_NUMBER_OF_ROWS must be positive integers. As with the
     table-level options with the same names, these act only as
     `suggestions' to the server and are not hard limits.

   * The optional `TABLESPACE' clause may be used to designate a
     tablespace for the partition. Used for MySQL Cluster only.

   * The partitioning handler accepts a `[STORAGE] ENGINE' option for
     both `PARTITION' and `SUBPARTITION'. Currently, the only way in
     which this can be used is to set all partitions or all
     subpartitions to the same storage engine, and an attempt to set
     different storage engines for partitions or subpartitions in the
     same table will give rise to the error `ERROR 1469 (HY000): The
     mix of handlers in the partitions is not allowed in this version
     of MySQL'. We expect to lift this restriction on partitioning in a
     future MySQL release.

   * The `NODEGROUP' option can be used to make this partition act as
     part of the node group identified by NODE_GROUP_ID. This option is
     applicable only to MySQL Cluster.

   * The partition definition may optionally contain one or more
     SUBPARTITION_DEFINITION clauses.  Each of these consists at a
     minimum of the `SUBPARTITION NAME', where NAME is an identifier
     for the subpartition. Except for the replacement of the
     `PARTITION' keyword with `SUBPARTITION', the syntax for a
     subpartition definition is identical to that for a partition
     definition.

     Subpartitioning must be done by `HASH' or `KEY', and can be done
     only on `RANGE' or `LIST' partitions. See *Note
     partitioning-subpartitions::.

Partitions can be modified, merged, added to tables, and dropped from
tables. For basic information about the MySQL statements to accomplish
these tasks, see *Note alter-table::. For more detailed descriptions
and examples, see *Note partitioning-management::.

*Important*:

The original `CREATE TABLE' statement, including all specifications and
table options are stored by MySQL when the table is created. The
information is retained so that if you change storage engines,
collations or other settings using an `ALTER TABLE' statement, the
original table options specified are retained. This allows you to change
between `InnoDB' and `MyISAM' table types even though the row formats
supported by the two engines are different.

Because the text of the original statement is retained, but due to the
way that certain values and options may be silently reconfigured (such
as the `ROW_FORMAT'), the active table definition (accessible through
`DESCRIBE' or with `SHOW TABLE STATUS' and the table creation string
(accessible through `SHOW CREATE TABLE') will report different values.

You can create one table from another by adding a `SELECT' statement at
the end of the `CREATE TABLE' statement:

     CREATE TABLE NEW_TBL SELECT * FROM ORIG_TBL;

MySQL creates new columns for all elements in the `SELECT'. For example:

     mysql> CREATE TABLE test (a INT NOT NULL AUTO_INCREMENT,
         ->        PRIMARY KEY (a), KEY(b))
         ->        ENGINE=MyISAM SELECT b,c FROM test2;

This creates a `MyISAM' table with three columns, `a', `b', and `c'.
Notice that the columns from the `SELECT' statement are appended to the
right side of the table, not overlapped onto it. Take the following
example:

     mysql> SELECT * FROM foo;
     +---+
     | n |
     +---+
     | 1 |
     +---+

     mysql> CREATE TABLE bar (m INT) SELECT n FROM foo;
     Query OK, 1 row affected (0.02 sec)
     Records: 1  Duplicates: 0  Warnings: 0

     mysql> SELECT * FROM bar;
     +------+---+
     | m    | n |
     +------+---+
     | NULL | 1 |
     +------+---+
     1 row in set (0.00 sec)

For each row in table `foo', a row is inserted in `bar' with the values
from `foo' and default values for the new columns.

In a table resulting from `CREATE TABLE ...  SELECT', columns named
only in the `CREATE TABLE' part come first. Columns named in both parts
or only in the `SELECT' part come after that. The data type of `SELECT'
columns can be overridden by also specifying the column in the `CREATE
TABLE' part.

If any errors occur while copying the data to the table, it is
automatically dropped and not created.

`CREATE TABLE ... SELECT' does not automatically create any indexes for
you. This is done intentionally to make the statement as flexible as
possible. If you want to have indexes in the created table, you should
specify these before the `SELECT' statement:

     mysql> CREATE TABLE bar (UNIQUE (n)) SELECT n FROM foo;

Some conversion of data types might occur. For example, the
`AUTO_INCREMENT' attribute is not preserved, and `VARCHAR' columns can
become `CHAR' columns. Retrained attributes are `NULL' (or `NOT NULL')
and, for those columns that have them, `CHARACTER SET', `COLLATION',
`COMMENT', and the `DEFAULT' clause.

When creating a table with `CREATE ... SELECT', make sure to alias any
function calls or expressions in the query.  If you do not, the
`CREATE' statement might fail or result in undesirable column names.

     CREATE TABLE artists_and_works
       SELECT artist.name, COUNT(work.artist_id) AS number_of_works
       FROM artist LEFT JOIN work ON artist.id = work.artist_id
       GROUP BY artist.id;

You can also explicitly specify the data type for a generated column:

     CREATE TABLE foo (a TINYINT NOT NULL) SELECT b+1 AS a FROM bar;

Use `LIKE' to create an empty table based on the definition of another
table, including any column attributes and indexes defined in the
original table:

     CREATE TABLE NEW_TBL LIKE ORIG_TBL;

The copy is created using the same version of the table storage format
as the original table. The `SELECT' privilege is required on the
original table.

`LIKE' works only for base tables, not for views.

`CREATE TABLE ... LIKE' does not preserve any `DATA DIRECTORY' or `INDEX
DIRECTORY' table options that were specified for the original table, or
any foreign key definitions.

You can precede the `SELECT' by `IGNORE' or `REPLACE' to indicate how
to handle rows that duplicate unique key values. With `IGNORE', new
rows that duplicate an existing row on a unique key value are
discarded. With `REPLACE', new rows replace rows that have the same
unique key value. If neither `IGNORE' nor `REPLACE' is specified,
duplicate unique key values result in an error.

To ensure that the binary log can be used to re-create the original
tables, MySQL does not allow concurrent inserts during `CREATE TABLE
... SELECT'.


File: manual.info,  Node: silent-column-changes,  Prev: create-table,  Up: create-table

12.1.10.1 Silent Column Specification Changes
.............................................

In some cases, MySQL silently changes column specifications from those
given in a `CREATE TABLE' or `ALTER TABLE' statement. These might be
changes to a data type, to attributes associated with a data type, or to
an index specification.

   * `TIMESTAMP' display sizes are discarded.

     Also note that `TIMESTAMP' columns are `NOT NULL' by default.

   * Columns that are part of a `PRIMARY KEY' are made `NOT NULL' even
     if not declared that way.

   * Trailing spaces are automatically deleted from `ENUM' and `SET'
     member values when the table is created.

   * MySQL maps certain data types used by other SQL database vendors
     to MySQL types. See *Note other-vendor-data-types::.

   * If you include a `USING' clause to specify an index type that is
     not legal for a given storage engine, but there is another index
     type available that the engine can use without affecting query
     results, the engine uses the available type.

   * If strict SQL mode is not enabled, a `VARCHAR' column with a length
     specification greater than 65535 is converted to `TEXT', and a
     `VARBINARY' column with a length specification greater than 65535
     is converted to `BLOB'. Otherwise, an error occurs in either of
     these cases.

   * Specifying the `CHARACTER SET binary' attribute for a character
     data type causes the column to be created as the corresponding
     binary data type: `CHAR' becomes `BINARY', `VARCHAR' becomes
     `VARBINARY', and `TEXT' becomes `BLOB'. For the `ENUM' and `SET'
     data types, this does not occur; they are created as declared.
     Suppose that you specify a table using this definition:

          CREATE TABLE t
          (
            c1 VARCHAR(10) CHARACTER SET binary,
            c2 TEXT CHARACTER SET binary,
            c3 ENUM('a','b','c') CHARACTER SET binary
          );

     The resulting table has this definition:

          CREATE TABLE t
          (
            c1 VARBINARY(10),
            c2 BLOB,
            c3 ENUM('a','b','c') CHARACTER SET binary
          );

To see whether MySQL used a data type other than the one you specified,
issue a `DESCRIBE' or `SHOW CREATE TABLE' statement after creating or
altering the table.

Certain other data type changes can occur if you compress a table using
`myisampack'. See *Note compressed-format::.


File: manual.info,  Node: create-tablespace,  Next: drop-database,  Prev: create-table,  Up: sql-syntax-data-definition

12.1.11 `CREATE TABLESPACE' Syntax
----------------------------------

     CREATE TABLESPACE TABLESPACE_NAME
         ADD DATAFILE 'FILE_NAME'
         USE LOGFILE GROUP LOGFILE_GROUP
         [EXTENT_SIZE [=] EXTENT_SIZE]
         [INITIAL_SIZE [=] INITIAL_SIZE]
         [AUTOEXTEND_SIZE [=] AUTOEXTEND_SIZE]
         [MAX_SIZE [=] MAX_SIZE]
         [NODEGROUP [=] NODEGROUP_ID]
         [WAIT]
         [COMMENT [=] COMMENT_TEXT]
         ENGINE [=] ENGINE_NAME

This statement is used to create a tablespace, which can contain one or
more data files, providing storage space for tables. One data file is
created and added to the tablespace using this statement. Additional
data files may be added to the tablespace by using the `ALTER
TABLESPACE' statement (see *Note alter-tablespace::). For rules
covering the naming of tablespaces, see *Note identifiers::.

A log file group of one or more `UNDO' log files must be assigned to
the tablespace to be created with the `USE LOGFILE GROUP' clause.
LOGFILE_GROUP must be an existing log file group created with `CREATE
LOGFILE GROUP' (see *Note create-logfile-group::). Multiple tablespaces
may use the same log file group for `UNDO' logging.

The `EXTENT_SIZE' sets the size, in bytes, of the extents used by any
files belonging to the tablespace. The default value is 1M. The minimum
size is 32K, and the theoretical maximum is 2G, although the practical
maximum size depends on a number of factors.

An _extent_ is a unit of disk space allocation. One extent is filled
with as much data as that extent can contain before another extent is
used. In theory, up to 65,535 (64K) extents may used per data file;
however, the recommended maximum is 32,768 (32K). The recommended
maximum size for a single data file is 32G -- that is, 32K extents x 1
MB per extent. Smaller extents have the advantage that they tend to
provide lower latency; however, larger extents tend to allow for
greater throughput. You must also take into consideration that larger
extents may mean longer node restart times. In addition, once an extent
is allocated to a given table, it cannot be used to store data from
another; an extent cannot store table from more than one table. This
means, for example that a tablespace having a single datafile whose
`INITIAL_SIZE' is 256 MB and whose `EXTENT_SIZE' is 128M has just two
extents, and so can be used to store data from at most two different
disk data tables.

You can see how many extents remain free in a given data file by
querying the `INFORMATION_SCHEMA.FILES' table, and so derive an
estimate for how much space remains free in the file. For further
discussion and examples, see *Note files-table::.

The `INITIAL_SIZE' parameter sets the data file's total size in bytes.
Once the file has been created, its size cannot be changed; however,
you can add more data files to the tablespace using `ALTER TABLESPACE
... ADD DATAFILE'. See *Note alter-tablespace::.

`INITIAL_SIZE' is optional; its default value is `128M'.

On 32-bit systems, the maximum supported value for `INITIAL_SIZE' is
`4G'. (Bug#29186 (http://bugs.mysql.com/29186))

When setting `EXTENT_SIZE' or `INITIAL_SIZE' (either or both), you may
optionally follow the number with a one-letter abbreviation for an
order of magnitude, similar to those used in `my.cnf'. Generally, this
is one of the letters `M' (for megabytes) or `G' (for gigabytes).

`AUTOEXTEND_SIZE', `MAX_SIZE', `NODEGROUP', `WAIT', and `COMMENT' are
parsed but ignored, and so have no effect in MySQL 5.1. These options
are intended for future expansion.

The `ENGINE' parameter determines the storage engine which uses this
tablespace, with ENGINE_NAME being the name of the storage engine. In
MySQL 5.1, ENGINE_NAME must be one of the values `NDB' or `NDBCLUSTER'.

When `CREATE TABLESPACE' is used with `ENGINE = NDB', a tablespace and
associated data file are created on each Cluster data node. You can
verify that the data files were created and obtain information about
them by querying the `INFORMATION_SCHEMA.FILES' table.  For example:

     mysql> SELECT LOGFILE_GROUP_NAME, FILE_NAME, EXTRA
         -> FROM INFORMATION_SCHEMA.FILES
         -> WHERE TABLESPACE_NAME = 'newts' AND FILE_TYPE = 'DATAFILE';
     +--------------------+-------------+----------------+
     | LOGFILE_GROUP_NAME | FILE_NAME   | EXTRA          |
     +--------------------+-------------+----------------+
     | lg_3               | newdata.dat | CLUSTER_NODE=3 |
     | lg_3               | newdata.dat | CLUSTER_NODE=4 |
     +--------------------+-------------+----------------+
     2 rows in set (0.01 sec)

(See *Note files-table::.)

`CREATE TABLESPACE' was added in MySQL 5.1.6. In MySQL 5.1, it is
useful only with Disk Data storage for MySQL Cluster. See *Note
mysql-cluster-disk-data::.


File: manual.info,  Node: drop-database,  Next: drop-index,  Prev: create-tablespace,  Up: sql-syntax-data-definition

12.1.12 `DROP DATABASE' Syntax
------------------------------

     DROP {DATABASE | SCHEMA} [IF EXISTS] DB_NAME

`DROP DATABASE' drops all tables in the database and deletes the
database. Be _very_ careful with this statement! To use `DROP
DATABASE', you need the `DROP' privilege on the database.  `DROP
SCHEMA' is a synonym for `DROP DATABASE'.

*Important*:

When a database is dropped, user privileges on the database are _not_
automatically dropped. See *Note grant::.

`IF EXISTS' is used to prevent an error from occurring if the database
does not exist.

If you use `DROP DATABASE' on a symbolically linked database, both the
link and the original database are deleted.

`DROP DATABASE' returns the number of tables that were removed. This
corresponds to the number of `.frm' files removed.

The `DROP DATABASE' statement removes from the given database directory
those files and directories that MySQL itself may create during normal
operation:

   * All files with these extensions:

     `.BAK'  `.DAT'  `.HSH'  `.MRG'
     `.MYD'  `.MYI'  `.TRG'  `.TRN'
     `.db'   `.frm'  `.ibd'  `.ndb'
     `.par'                  

   * The `db.opt' file, if it exists.

If other files or directories remain in the database directory after
MySQL removes those just listed, the database directory cannot be
removed. In this case, you must remove any remaining files or
directories manually and issue the `DROP DATABASE' statement again.

You can also drop databases with `mysqladmin'.  See *Note mysqladmin::.


File: manual.info,  Node: drop-index,  Next: drop-logfile-group,  Prev: drop-database,  Up: sql-syntax-data-definition

12.1.13 `DROP INDEX' Syntax
---------------------------

     DROP [ONLINE|OFFLINE] INDEX INDEX_NAME ON TBL_NAME

`DROP INDEX' drops the index named INDEX_NAME from the table TBL_NAME.
This statement is mapped to an `ALTER TABLE' statement to drop the
index. See *Note alter-table::.

Beginning with MySQL 5.1.7, indexes on variable-width columns are
dropped online; that is, dropping the indexes does not require any
copying or locking of the table. This is done automatically by the
server whenever it determines that it is possible to do so; you do not
have to use any special SQL syntax or server options to cause it to
happen.

In standard MySQL 5.1 releases, it is not possible to override the
server when it determines that an index is to be dropped online. In
MySQL Cluster, beginning with MySQL Cluster NDB 6.2.5 and MySQL Cluster
NDB 6.3.3, you can drop indexes offline (which causes the table to be
locked) using the `OFFLINE' keyword. The rules and limitations
governing online `DROP OFFLINE INDEX' and `DROP ONLINE INDEX' are the
same as for `ALTER OFFLINE TABLE ... DROP INDEX' and `ALTER ONLINE
TABLE ... DROP INDEX'. You cannot cause the online dropping of an index
that would normally be dropped offline by using the `ONLINE' keyword (if
it is not possible to perform the `DROP' operation online, then the
`ONLINE' keyword is ignored). For more information, see *Note
alter-table::.

*Note*:

The `ONLINE' and `OFFLINE' keywords are available only in MySQL Cluster
NDB 6.2 and MySQL Cluster NDB 6.3 releases beginning with versions
6.2.5 and 6.3.3, respectively; attempting to use them in earlier MySQL
Cluster NDB 6.2 or 6.3 releases, standard MySQL 5.1 releases, or MySQL
Cluster NDB 6.1 releases results in a syntax error.


File: manual.info,  Node: drop-logfile-group,  Next: drop-server,  Prev: drop-index,  Up: sql-syntax-data-definition

12.1.14 `DROP LOGFILE GROUP' Syntax
-----------------------------------

     DROP LOGFILE GROUP LOGFILE_GROUP
         ENGINE [=] ENGINE_NAME

This statement drops the log file group named LOGFILE_GROUP. The log
file group must already exist or an error results. (For information on
creating log file groups, see *Note create-logfile-group::.)

*Important*:

Before dropping a log file group, you must drop all tablespaces that
use that log file group for `UNDO' logging.

The required `ENGINE' clause provides the name of the storage engine
used by the log file group to be dropped. In MySQL 5.1, the only
permitted values for ENGINE_NAME are `NDB' and `NDBCLUSTER'.

`DROP LOGFILE GROUP' was added in MySQL 5.1.6. In MySQL 5.1, it is
useful only with Disk Data storage for MySQL Cluster. See *Note
mysql-cluster-disk-data::.


File: manual.info,  Node: drop-server,  Next: drop-table,  Prev: drop-logfile-group,  Up: sql-syntax-data-definition

12.1.15 `DROP SERVER' Syntax
----------------------------

     DROP SERVER [ IF EXISTS ] SERVER_NAME

Drops the server definition for the server named `SERVER_NAME'. The
corresponding row within the `mysql.servers' table will be deleted.
This statement requires the `SUPER' privilege.

Dropping a server for a table does not affect any `FEDERATED' tables
that used this connection information when they were created. See *Note
create-server::.

`DROP SERVER' does not cause an automatic commit.

`DROP SERVER' was added in MySQL 5.1.15.


File: manual.info,  Node: drop-table,  Next: drop-tablespace,  Prev: drop-server,  Up: sql-syntax-data-definition

12.1.16 `DROP TABLE' Syntax
---------------------------

     DROP [TEMPORARY] TABLE [IF EXISTS]
         TBL_NAME [, TBL_NAME] ...
         [RESTRICT | CASCADE]

`DROP TABLE' removes one or more tables. You must have the `DROP'
privilege for each table. All table data and the table definition are
_removed_, so _be careful_ with this statement! If any of the tables
named in the argument list do not exist, MySQL returns an error
indicating by name which non-existing tables it was unable to drop, but
it also drops all of the tables in the list that do exist.

*Important*:

When a table is dropped, user privileges on the table are _not_
automatically dropped. See *Note grant::.

Note that for a partitioned table, `DROP TABLE' permanently removes the
table definition, all of its partitions, and all of the data which was
stored in those partitions. It also removes the partitioning definition
(`.par') file associated with the dropped table.

Use `IF EXISTS' to prevent an error from occurring for tables that do
not exist. A `NOTE' is generated for each non-existent table when using
`IF EXISTS'. See *Note show-warnings::.

`RESTRICT' and `CASCADE' are allowed to make porting easier. In MySQL
5.1, they do nothing.

*Note*:

`DROP TABLE' automatically commits the current active transaction,
unless you use the `TEMPORARY' keyword.

The `TEMPORARY' keyword has the following effects:

   * The statement drops only `TEMPORARY' tables.

   * The statement does not end an ongoing transaction.

   * No access rights are checked. (A `TEMPORARY' table is visible only
     to the client that created it, so no check is necessary.)

Using `TEMPORARY' is a good way to ensure that you do not accidentally
drop a non-`TEMPORARY' table.


File: manual.info,  Node: drop-tablespace,  Next: rename-database,  Prev: drop-table,  Up: sql-syntax-data-definition

12.1.17 `DROP TABLESPACE' Syntax
--------------------------------

     DROP TABLESPACE TABLESPACE_NAME
         ENGINE [=] ENGINE_NAME

This statement drops a tablespace that was previously created using
`CREATE TABLESPACE' (see *Note create-tablespace::).

*Important*:

The tablespace to be dropped must not contain any data files; in other
words, before you can drop a tablespace, you must first drop each of
its data files using `ALTER TABLESPACE ...  DROP DATAFILE' (see *Note
alter-tablespace::).

The `ENGINE' clause (required) specifies the storage engine used by the
tablespace. In MySQL 5.1, the only accepted values for ENGINE_NAME are
`NDB' and `NDBCLUSTER'.

`DROP TABLESPACE' was added in MySQL 5.1.6. In MySQL 5.1, it is useful
only with Disk Data storage for MySQL Cluster. See *Note
mysql-cluster-disk-data::.


File: manual.info,  Node: rename-database,  Next: rename-table,  Prev: drop-tablespace,  Up: sql-syntax-data-definition

12.1.18 `RENAME DATABASE' Syntax
--------------------------------

     RENAME {DATABASE | SCHEMA} DB_NAME TO NEW_DB_NAME;

This statement was added in MySQL 5.1.7 but was found to be dangerous
and was removed in MySQL 5.1.23. It was intended to enable upgrading
pre-5.1 databases to use the encoding implemented in 5.1 for mapping
database names to database directory names (see *Note
identifier-mapping::). However, use of this statement could result in
loss of database contents, which is why it was removed. Do not use
`RENAME DATABASE' in earlier versions in which it is present.

To perform the task of upgrading database names with the new encoding,
use `ALTER DATABASE DB_NAME UPGRADE DATA DIRECTORY NAME' instead (see
*Note alter-database::).


File: manual.info,  Node: rename-table,  Prev: rename-database,  Up: sql-syntax-data-definition

12.1.19 `RENAME TABLE' Syntax
-----------------------------

     RENAME TABLE TBL_NAME TO NEW_TBL_NAME
         [, TBL_NAME2 TO NEW_TBL_NAME2] ...

This statement renames one or more tables.

The rename operation is done atomically, which means that no other
thread can access any of the tables while the rename is running.  For
example, if you have an existing table `old_table', you can create
another table `new_table' that has the same structure but is empty, and
then replace the existing table with the empty one as follows (assuming
that `backup_table' does not already exist):

     CREATE TABLE new_table (...);
     RENAME TABLE old_table TO backup_table, new_table TO old_table;

If the statement renames more than one table, renaming operations are
done from left to right. If you want to swap two table names, you can
do so like this (assuming that `tmp_table' does not already exist):

     RENAME TABLE old_table TO tmp_table,
                  new_table TO old_table,
                  tmp_table TO new_table;

As long as two databases are on the same filesystem, you can use
`RENAME TABLE' to move a table from one database to another:

     RENAME TABLE CURRENT_DB.TBL_NAME TO OTHER_DB.TBL_NAME;

If there are any triggers associated with a table which is moved to a
different database using `RENAME TABLE', then the statement fails with
the error `Trigger in wrong schema'.

`RENAME TABLE' also works for views, as long as you do not try to
rename a view into a different database.

Any privileges granted specifically for the renamed table or view are
not migrated to the new name. They must be changed manually.

When you execute `RENAME', you cannot have any locked tables or active
transactions. You must also have the `ALTER' and `DROP' privileges on
the original table, and the `CREATE' and `INSERT' privileges on the new
table.

If MySQL encounters any errors in a multiple-table rename, it does a
reverse rename for all renamed tables to return everything to its
original state.


File: manual.info,  Node: sql-syntax-data-manipulation,  Next: sql-syntax-utility,  Prev: sql-syntax-data-definition,  Up: sql-syntax

12.2 Data Manipulation Statements
=================================

* Menu:

* delete::                       `DELETE' Syntax
* do::                           `DO' Syntax
* handler::                      `HANDLER' Syntax
* insert::                       `INSERT' Syntax
* load-data::                    `LOAD DATA INFILE' Syntax
* replace::                      `REPLACE' Syntax
* select::                       `SELECT' Syntax
* subqueries::                   Subquery Syntax
* truncate::                     `TRUNCATE' Syntax
* update::                       `UPDATE' Syntax


File: manual.info,  Node: delete,  Next: do,  Prev: sql-syntax-data-manipulation,  Up: sql-syntax-data-manipulation

12.2.1 `DELETE' Syntax
----------------------

Single-table syntax:

     DELETE [LOW_PRIORITY] [QUICK] [IGNORE] FROM TBL_NAME
         [WHERE WHERE_CONDITION]
         [ORDER BY ...]
         [LIMIT ROW_COUNT]

Multiple-table syntax:

     DELETE [LOW_PRIORITY] [QUICK] [IGNORE]
         TBL_NAME[.*] [, TBL_NAME[.*]] ...
         FROM TABLE_REFERENCES
         [WHERE WHERE_CONDITION]

Or:

     DELETE [LOW_PRIORITY] [QUICK] [IGNORE]
         FROM TBL_NAME[.*] [, TBL_NAME[.*]] ...
         USING TABLE_REFERENCES
         [WHERE WHERE_CONDITION]

For the single-table syntax, the `DELETE' statement deletes rows from
TBL_NAME and returns a count of the number of deleted rows. This count
can be obtained by calling the `ROW_COUNT()' function (see *Note
information-functions::). The `WHERE' clause, if given, specifies the
conditions that identify which rows to delete. With no `WHERE' clause,
all rows are deleted. If the `ORDER BY' clause is specified, the rows
are deleted in the order that is specified. The `LIMIT' clause places a
limit on the number of rows that can be deleted.

For the multiple-table syntax, `DELETE' deletes from each TBL_NAME the
rows that satisfy the conditions. In this case, `ORDER BY' and `LIMIT'
cannot be used.

WHERE_CONDITION is an expression that evaluates to true for each row to
be deleted. It is specified as described in *Note select::.

Currently, you cannot delete from a table and select from the same
table in a subquery.

As stated, a `DELETE' statement with no `WHERE' clause deletes all
rows. A faster way to do this, when you do not need to know the number
of deleted rows, is to use `TRUNCATE TABLE'. However, within a
transaction or if you have a lock on the table, `TRUNCATE TABLE' cannot
be used whereas `DELETE' can. See *Note truncate::, and *Note
lock-tables::.

If you delete the row containing the maximum value for an
`AUTO_INCREMENT' column, the value is not reused for a `MyISAM' or
`InnoDB' table. If you delete all rows in the table with `DELETE FROM
TBL_NAME' (without a `WHERE' clause) in `AUTOCOMMIT' mode, the sequence
starts over for all storage engines except `InnoDB' and `MyISAM'. There
are some exceptions to this behavior for `InnoDB' tables, as discussed
in *Note innodb-auto-increment-handling::.

For `MyISAM' tables, you can specify an `AUTO_INCREMENT' secondary
column in a multiple-column key. In this case, reuse of values deleted
from the top of the sequence occurs even for `MyISAM' tables. See *Note
example-auto-increment::.

The `DELETE' statement supports the following modifiers:

   * If you specify `LOW_PRIORITY', the server delays execution of the
     `DELETE' until no other clients are reading from the table. This
     affects only storage engines that use only table-level locking
     (`MyISAM', `MEMORY', `MERGE').

   * For `MyISAM' tables, if you use the `QUICK' keyword, the storage
     engine does not merge index leaves during delete, which may speed
     up some kinds of delete operations.

   * The `IGNORE' keyword causes MySQL to ignore all errors during the
     process of deleting rows. (Errors encountered during the parsing
     stage are processed in the usual manner.) Errors that are ignored
     due to the use of `IGNORE' are returned as warnings.

The speed of delete operations may also be affected by factors
discussed in *Note delete-speed::.

In `MyISAM' tables, deleted rows are maintained in a linked list and
subsequent `INSERT' operations reuse old row positions. To reclaim
unused space and reduce file sizes, use the `OPTIMIZE TABLE' statement
or the `myisamchk' utility to reorganize tables. `OPTIMIZE TABLE' is
easier to use, but `myisamchk' is faster. See *Note optimize-table::,
and *Note myisamchk::.

The `QUICK' modifier affects whether index leaves are merged for delete
operations. `DELETE QUICK' is most useful for applications where index
values for deleted rows are replaced by similar index values from rows
inserted later. In this case, the holes left by deleted values are
reused.

`DELETE QUICK' is not useful when deleted values lead to underfilled
index blocks spanning a range of index values for which new inserts
occur again. In this case, use of `QUICK' can lead to wasted space in
the index that remains unreclaimed. Here is an example of such a
scenario:

  1. Create a table that contains an indexed `AUTO_INCREMENT' column.

  2. Insert many rows into the table. Each insert results in an index
     value that is added to the high end of the index.

  3. Delete a block of rows at the low end of the column range using
     `DELETE QUICK'.

In this scenario, the index blocks associated with the deleted index
values become underfilled but are not merged with other index blocks
due to the use of `QUICK'. They remain underfilled when new inserts
occur, because new rows do not have index values in the deleted range.
Furthermore, they remain underfilled even if you later use `DELETE'
without `QUICK', unless some of the deleted index values happen to lie
in index blocks within or adjacent to the underfilled blocks. To
reclaim unused index space under these circumstances, use `OPTIMIZE
TABLE'.

If you are going to delete many rows from a table, it might be faster
to use `DELETE QUICK' followed by `OPTIMIZE TABLE'. This rebuilds the
index rather than performing many index block merge operations.

The MySQL-specific `LIMIT ROW_COUNT' option to `DELETE' tells the
server the maximum number of rows to be deleted before control is
returned to the client. This can be used to ensure that a given `DELETE'
statement does not take too much time. You can simply repeat the
`DELETE' statement until the number of affected rows is less than the
`LIMIT' value.

If the `DELETE' statement includes an `ORDER BY' clause, rows are
deleted in the order specified by the clause. This is useful primarily
in conjunction with `LIMIT'. For example, the following statement finds
rows matching the `WHERE' clause, sorts them by `timestamp_column', and
deletes the first (oldest) one:

     DELETE FROM somelog WHERE user = 'jcole'
     ORDER BY timestamp_column LIMIT 1;

`ORDER BY' may also be useful in some cases to delete rows in an order
required to avoid referential integrity violations.

You can specify multiple tables in a `DELETE' statement to delete rows
from one or more tables depending on the particular condition in the
`WHERE' clause.  However, you cannot use `ORDER BY' or `LIMIT' in a
multiple-table `DELETE'. The TABLE_REFERENCES clause lists the tables
involved in the join. Its syntax is described in *Note join::.

For the first multiple-table syntax, only matching rows from the tables
listed before the `FROM' clause are deleted. For the second
multiple-table syntax, only matching rows from the tables listed in the
`FROM' clause (before the `USING' clause) are deleted. The effect is
that you can delete rows from many tables at the same time and have
additional tables that are used only for searching:

     DELETE t1, t2 FROM t1 INNER JOIN t2 INNER JOIN t3
     WHERE t1.id=t2.id AND t2.id=t3.id;

Or:

     DELETE FROM t1, t2 USING t1 INNER JOIN t2 INNER JOIN t3
     WHERE t1.id=t2.id AND t2.id=t3.id;

These statements use all three tables when searching for rows to
delete, but delete matching rows only from tables `t1' and `t2'.

The preceding examples show inner joins that use the comma operator,
but multiple-table `DELETE' statements can use other types of join
allowed in `SELECT' statements, such as `LEFT JOIN'. For example, to
delete rows that exist in `t1' that have no match in `t2', use a `LEFT
JOIN':

     DELETE t1 FROM t1 LEFT JOIN t2 ON t1.id=t2.id WHERE t2.id IS NULL;

The syntax allows `.*' after each TBL_NAME for compatibility with
`Access'.

If you use a multiple-table `DELETE' statement involving `InnoDB'
tables for which there are foreign key constraints, the MySQL optimizer
might process tables in an order that differs from that of their
parent/child relationship. In this case, the statement fails and rolls
back.  Instead, you should delete from a single table and rely on the
`ON DELETE' capabilities that `InnoDB' provides to cause the other
tables to be modified accordingly.

*Note*:

If you declare an alias for a table, you must use the alias when
referring to the table:

     DELETE t1 FROM test AS t1, test2 WHERE ...

Table aliases in a multiple-table `DELETE' statement should be declared
only in the TABLE_REFERENCES part. Elsewhere in the statement, alias
references are allowed but not alias declarations.

Correct:

     DELETE a1, a2 FROM t1 AS a2 INNER JOIN t2 AS a2
     WHERE a1.id=a2.id;

     DELETE FROM a1, a2 USING t1 AS a2 INNER JOIN t2 AS a2
     WHERE a1.id=a2.id;

Incorrect:

     DELETE t1 AS a1, t2 AS a2 FROM t1 INNER JOIN t2
     WHERE a1.id=a2.id;

     DELETE FROM t1 AS a1, t2 AS a2 USING t1 INNER JOIN t2
     WHERE a1.id=a2.id;

Declaration of aliases other than in the TABLE_REFERENCES part can lead
to ambiguous statements that have unexpected results such as deleting
rows from the wrong table. This is such a statement:

     DELETE FROM t1 AS a2 USING t1 AS a1 INNER JOIN t2 AS a2;

Before MySQL 5.1.23, alias declarations are allowed in other than the
TABLE_REFERENCES part, but should be avoided for the reason just
mentioned.

Cross-database deletes are supported for multiple-table deletes, but in
this case, you must refer to the tables without using aliases. For
example:

     DELETE test1.tmp1, test2.tmp2 FROM test1.tmp1, test2.tmp2 WHERE ...


File: manual.info,  Node: do,  Next: handler,  Prev: delete,  Up: sql-syntax-data-manipulation

12.2.2 `DO' Syntax
------------------

     DO EXPR [, EXPR] ...

`DO' executes the expressions but does not return any results. In most
respects, `DO' is shorthand for `SELECT EXPR, ...', but has the
advantage that it is slightly faster when you do not care about the
result.

`DO' is useful primarily with functions that have side effects, such as
`RELEASE_LOCK()'.


File: manual.info,  Node: handler,  Next: insert,  Prev: do,  Up: sql-syntax-data-manipulation

12.2.3 `HANDLER' Syntax
-----------------------

     HANDLER TBL_NAME OPEN [ [AS] ALIAS]
     HANDLER TBL_NAME READ INDEX_NAME { = | >= | <= | < } (VALUE1,VALUE2,...)
         [ WHERE WHERE_CONDITION ] [LIMIT ... ]
     HANDLER TBL_NAME READ INDEX_NAME { FIRST | NEXT | PREV | LAST }
         [ WHERE WHERE_CONDITION ] [LIMIT ... ]
     HANDLER TBL_NAME READ { FIRST | NEXT }
         [ WHERE WHERE_CONDITION ] [LIMIT ... ]
     HANDLER TBL_NAME CLOSE

The `HANDLER' statement provides direct access to table storage engine
interfaces. It is available for `MyISAM' and `InnoDB' tables.

The `HANDLER ... OPEN' statement opens a table, making it accessible
via subsequent `HANDLER ...  READ' statements. This table object is not
shared by other threads and is not closed until the thread calls
`HANDLER ... CLOSE' or the thread terminates. If you open the table
using an alias, further references to the open table with other
`HANDLER' statements must use the alias rather than the table name.

The first `HANDLER ... READ' syntax fetches a row where the index
specified satisfies the given values and the `WHERE' condition is met.
If you have a multiple-column index, specify the index column values as
a comma-separated list. Either specify values for all the columns in
the index, or specify values for a leftmost prefix of the index
columns. Suppose that an index `my_idx' includes three columns named
`col_a', `col_b', and `col_c', in that order. The `HANDLER' statement
can specify values for all three columns in the index, or for the
columns in a leftmost prefix. For example:

     HANDLER ... READ my_idx = (col_a_val,col_b_val,col_c_val) ...
     HANDLER ... READ my_idx = (col_a_val,col_b_val) ...
     HANDLER ... READ my_idx = (col_a_val) ...

To employ the `HANDLER' interface to refer to a table's `PRIMARY KEY',
use the quoted identifier ``PRIMARY`':

     HANDLER TBL_NAME READ `PRIMARY` ...

The second `HANDLER ... READ' syntax fetches a row from the table in
index order that matches the `WHERE' condition.

The third `HANDLER ... READ' syntax fetches a row from the table in
natural row order that matches the `WHERE' condition. It is faster than
`HANDLER TBL_NAME READ INDEX_NAME' when a full table scan is desired.
Natural row order is the order in which rows are stored in a `MyISAM'
table data file. This statement works for `InnoDB' tables as well, but
there is no such concept because there is no separate data file.

Without a `LIMIT' clause, all forms of `HANDLER ... READ' fetch a
single row if one is available. To return a specific number of rows,
include a `LIMIT' clause. It has the same syntax as for the `SELECT'
statement. See *Note select::.

`HANDLER ... CLOSE' closes a table that was opened with `HANDLER ...
OPEN'.

`HANDLER' is a somewhat low-level statement. For example, it does not
provide consistency. That is, `HANDLER ... OPEN' does _not_ take a
snapshot of the table, and does _not_ lock the table. This means that
after a `HANDLER ...  OPEN' statement is issued, table data can be
modified (by the current thread or other threads) and these
modifications might be only partially visible to `HANDLER ... NEXT' or
`HANDLER ... PREV' scans.

There are several reasons to use the `HANDLER' interface instead of
normal `SELECT' statements:

   * `HANDLER' is faster than `SELECT':

        * A designated storage engine handler object is allocated for
          the `HANDLER ... OPEN'. The object is reused for subsequent
          `HANDLER' statements for that table; it need not be
          reinitialized for each one.

        * There is less parsing involved.

        * There is no optimizer or query-checking overhead.

        * The table does not have to be locked between two handler
          requests.

        * The handler interface does not have to provide a consistent
          look of the data (for example, dirty reads are allowed), so
          the storage engine can use optimizations that `SELECT' does
          not normally allow.

   * For applications that use a low-level `ISAM'-like interface,
     `HANDLER' makes it much easier to port them to MySQL.

   * `HANDLER' enables you to traverse a database in a manner that is
     difficult (or even impossible) to accomplish with `SELECT'. The
     `HANDLER' interface is a more natural way to look at data when
     working with applications that provide an interactive user
     interface to the database.


File: manual.info,  Node: insert,  Next: load-data,  Prev: handler,  Up: sql-syntax-data-manipulation

12.2.4 `INSERT' Syntax
----------------------

* Menu:

* insert-select::                `INSERT ... SELECT' Syntax
* insert-delayed::               `INSERT DELAYED' Syntax
* insert-on-duplicate::          `INSERT ... ON DUPLICATE KEY UPDATE' Syntax

     INSERT [LOW_PRIORITY | DELAYED | HIGH_PRIORITY] [IGNORE]
         [INTO] TBL_NAME [(COL_NAME,...)]
         {VALUES | VALUE} ({EXPR | DEFAULT},...),(...),...
         [ ON DUPLICATE KEY UPDATE
           COL_NAME=EXPR
             [, COL_NAME=EXPR] ... ]

Or:

     INSERT [LOW_PRIORITY | DELAYED | HIGH_PRIORITY] [IGNORE]
         [INTO] TBL_NAME
         SET COL_NAME={EXPR | DEFAULT}, ...
         [ ON DUPLICATE KEY UPDATE
           COL_NAME=EXPR
             [, COL_NAME=EXPR] ... ]

Or:

     INSERT [LOW_PRIORITY | HIGH_PRIORITY] [IGNORE]
         [INTO] TBL_NAME [(COL_NAME,...)]
         SELECT ...
         [ ON DUPLICATE KEY UPDATE
           COL_NAME=EXPR
             [, COL_NAME=EXPR] ... ]

`INSERT' inserts new rows into an existing table.  The `INSERT ...
VALUES' and `INSERT ...  SET' forms of the statement insert rows based
on explicitly specified values. The `INSERT ...  SELECT' form inserts
rows selected from another table or tables. `INSERT ... SELECT' is
discussed further in *Note insert-select::.

You can use `REPLACE' instead of `INSERT' to overwrite old rows.
`REPLACE' is the counterpart to `INSERT IGNORE' in the treatment of new
rows that contain unique key values that duplicate old rows: The new
rows are used to replace the old rows rather than being discarded. See
*Note replace::.

TBL_NAME is the table into which rows should be inserted. The columns
for which the statement provides values can be specified as follows:

   * You can provide a comma-separated list of column names following
     the table name. In this case, a value for each named column must
     be provided by the `VALUES' list or the `SELECT' statement.

   * If you do not specify a list of column names for `INSERT ...
     VALUES' or `INSERT ...  SELECT', values for every column in the
     table must be provided by the `VALUES' list or the `SELECT'
     statement. If you do not know the order of the columns in the
     table, use `DESCRIBE TBL_NAME' to find out.

   * The `SET' clause indicates the column names explicitly.

Column values can be given in several ways:

   * If you are not running in strict SQL mode, any column not
     explicitly given a value is set to its default (explicit or
     implicit) value. For example, if you specify a column list that
     does not name all the columns in the table, unnamed columns are
     set to their default values. Default value assignment is described
     in *Note data-type-defaults::. See also *Note
     constraint-invalid-data::.

     If you want an `INSERT' statement to generate an error unless you
     explicitly specify values for all columns that do not have a
     default value, you should use strict mode.  See *Note
     server-sql-mode::.

   * Use the keyword `DEFAULT' to set a column explicitly to its
     default value. This makes it easier to write `INSERT' statements
     that assign values to all but a few columns, because it enables
     you to avoid writing an incomplete `VALUES' list that does not
     include a value for each column in the table. Otherwise, you would
     have to write out the list of column names corresponding to each
     value in the `VALUES' list.

     You can also use `DEFAULT(COL_NAME)' as a more general form that
     can be used in expressions to produce a given column's default
     value.

   * If both the column list and the `VALUES' list are empty, `INSERT'
     creates a row with each column set to its default value:

          INSERT INTO TBL_NAME () VALUES();

     In strict mode, an error occurs if any column doesn't have a
     default value. Otherwise, MySQL uses the implicit default value
     for any column that does not have an explicitly defined default.

   * You can specify an expression EXPR to provide a column value. This
     might involve type conversion if the type of the expression does
     not match the type of the column, and conversion of a given value
     can result in different inserted values depending on the data
     type. For example, inserting the string `'1999.0e-2'' into an
     `INT', `FLOAT', `DECIMAL(10,6)', or `YEAR' column results in the
     values `1999', `19.9921', `19.992100', and `1999' being inserted,
     respectively. The reason the value stored in the `INT' and `YEAR'
     columns is `1999' is that the string-to-integer conversion looks
     only at as much of the initial part of the string as may be
     considered a valid integer or year. For the floating-point and
     fixed-point columns, the string-to-floating-point conversion
     considers the entire string a valid floating-point value.

     An expression EXPR can refer to any column that was set earlier in
     a value list. For example, you can do this because the value for
     `col2' refers to `col1', which has previously been assigned:

          INSERT INTO TBL_NAME (col1,col2) VALUES(15,col1*2);

     But the following is not legal, because the value for `col1'
     refers to `col2', which is assigned after `col1':

          INSERT INTO TBL_NAME (col1,col2) VALUES(col2*2,15);

     One exception involves columns that contain `AUTO_INCREMENT'
     values. Because the `AUTO_INCREMENT' value is generated after
     other value assignments, any reference to an `AUTO_INCREMENT'
     column in the assignment returns a `0'.

`INSERT' statements that use `VALUES' syntax can insert multiple rows.
To do this, include multiple lists of column values, each enclosed
within parentheses and separated by commas. Example:

     INSERT INTO TBL_NAME (a,b,c) VALUES(1,2,3),(4,5,6),(7,8,9);

The values list for each row must be enclosed within parentheses.  The
following statement is illegal because the number of values in the list
does not match the number of column names:

     INSERT INTO TBL_NAME (a,b,c) VALUES(1,2,3,4,5,6,7,8,9);

`VALUE' is a synonym for `VALUES' in this context. Neither implies
anything about the number of values lists, and either may be used
whether there is a single values list or multiple lists.

The affected-rows value for an `INSERT' can be obtained using the
`ROW_COUNT()' function (see *Note information-functions::), or the
*Note `mysql_affected_rows()': mysql-affected-rows. C API function (see
*Note mysql-affected-rows::).

If you use an `INSERT ... VALUES' statement with multiple value lists
or `INSERT ... SELECT', the statement returns an information string in
this format:

     Records: 100 Duplicates: 0 Warnings: 0

`Records' indicates the number of rows processed by the statement.
(This is not necessarily the number of rows actually inserted because
`Duplicates' can be non-zero.) `Duplicates' indicates the number of
rows that could not be inserted because they would duplicate some
existing unique index value. `Warnings' indicates the number of
attempts to insert column values that were problematic in some way.
Warnings can occur under any of the following conditions:

   * Inserting `NULL' into a column that has been declared `NOT NULL'.
     For multiple-row `INSERT' statements or `INSERT INTO ... SELECT'
     statements, the column is set to the implicit default value for
     the column data type. This is `0' for numeric types, the empty
     string (`''') for string types, and the `zero' value for date and
     time types.  `INSERT INTO ... SELECT' statements are handled the
     same way as multiple-row inserts because the server does not
     examine the result set from the `SELECT' to see whether it returns
     a single row. (For a single-row `INSERT', no warning occurs when
     `NULL' is inserted into a `NOT NULL' column. Instead, the statement
     fails with an error.)

   * Setting a numeric column to a value that lies outside the column's
     range. The value is clipped to the closest endpoint of the range.

   * Assigning a value such as `'10.34 a'' to a numeric column. The
     trailing non-numeric text is stripped off and the remaining
     numeric part is inserted. If the string value has no leading
     numeric part, the column is set to `0'.

   * Inserting a string into a string column (`CHAR', `VARCHAR',
     `TEXT', or `BLOB') that exceeds the column's maximum length. The
     value is truncated to the column's maximum length.

   * Inserting a value into a date or time column that is illegal for
     the data type. The column is set to the appropriate zero value for
     the type.

If you are using the C API, the information string can be obtained by
invoking the *Note `mysql_info()': mysql-info.  function. See *Note
mysql-info::.

If `INSERT' inserts a row into a table that has an `AUTO_INCREMENT'
column, you can find the value used for that column by using the SQL
`LAST_INSERT_ID()' function. From within the C API, use the *Note
`mysql_insert_id()': mysql-insert-id. function.  However, you should
note that the two functions do not always behave identically. The
behavior of `INSERT' statements with respect to `AUTO_INCREMENT'
columns is discussed further in *Note information-functions::, and
*Note mysql-insert-id::.

The `INSERT' statement supports the following modifiers:

   * If you use the `DELAYED' keyword, the server puts the row or rows
     to be inserted into a buffer, and the client issuing the `INSERT
     DELAYED' statement can then continue immediately. If the table is
     in use, the server holds the rows. When the table is free, the
     server begins inserting rows, checking periodically to see whether
     there are any new read requests for the table. If there are, the
     delayed row queue is suspended until the table becomes free again.
     See *Note insert-delayed::.

     `DELAYED' is ignored with `INSERT ...  SELECT' or `INSERT ... ON
     DUPLICATE KEY UPDATE'.

     Beginning with MySQL 5.1.19, `DELAYED' is also disregarded for an
     `INSERT' that uses functions accessing tables or triggers, or that
     is called from a function or a trigger.

   * If you use the `LOW_PRIORITY' keyword, execution of the `INSERT'
     is delayed until no other clients are reading from the table. This
     includes other clients that began reading while existing clients
     are reading, and while the `INSERT LOW_PRIORITY' statement is
     waiting. It is possible, therefore, for a client that issues an
     `INSERT LOW_PRIORITY' statement to wait for a very long time (or
     even forever) in a read-heavy environment. (This is in contrast to
     `INSERT DELAYED', which lets the client continue at once.  Note
     that `LOW_PRIORITY' should normally not be used with `MyISAM'
     tables because doing so disables concurrent inserts. See *Note
     concurrent-inserts::.

     If you specify `HIGH_PRIORITY', it overrides the effect of the
     `--low-priority-updates' option if the server was started with
     that option. It also causes concurrent inserts not to be used. See
     *Note concurrent-inserts::.

     `LOW_PRIORITY' and `HIGH_PRIORITY' affect only storage engines
     that use only table-level locking (`MyISAM', `MEMORY', `MERGE').

   * If you use the `IGNORE' keyword, errors that occur while executing
     the `INSERT' statement are treated as warnings instead. For
     example, without `IGNORE', a row that duplicates an existing
     `UNIQUE' index or `PRIMARY KEY' value in the table causes a
     duplicate-key error and the statement is aborted. With `IGNORE',
     the row still is not inserted, but no error is issued.

     `IGNORE' has a similar effect on inserts into partitioned tables
     where no partition matching a given value is found. Without
     `IGNORE', such `INSERT' statements are aborted with an error;
     however, when `INSERT IGNORE' is used, the insert operation fails
     silently for the row containing the unmatched value, but any rows
     that are matched are inserted.  For an example, see *Note
     partitioning-list::.

     Data conversions that would trigger errors abort the statement if
     `IGNORE' is not specified. With `IGNORE', invalid values are
     adjusted to the closest values and inserted; warnings are produced
     but the statement does not abort. You can determine with the *Note
     `mysql_info()': mysql-info. C API function how many rows were
     actually inserted into the table.

   * If you specify `ON DUPLICATE KEY UPDATE', and a row is inserted
     that would cause a duplicate value in a `UNIQUE' index or `PRIMARY
     KEY', an `UPDATE' of the old row is performed. The affected-rows
     value per row is 1 if the row is inserted as a new row and 2 if an
     existing row is updated. See *Note insert-on-duplicate::.

Inserting into a table requires the `INSERT' privilege for the table.
If the `ON DUPLICATE KEY UPDATE' clause is used and a duplicate key
causes an `UPDATE' to be performed instead, the statement requires the
`UPDATE' privilege for the columns to be updated. For columns that are
read but not modified you need only the `SELECT' privilege (such as for
a column referenced only on the right hand side of an COL_NAME=EXPR
assignment in an `ON DUPLICATE KEY UPDATE' clause).


File: manual.info,  Node: insert-select,  Next: insert-delayed,  Prev: insert,  Up: insert

12.2.4.1 `INSERT ... SELECT' Syntax
...................................

     INSERT [LOW_PRIORITY | HIGH_PRIORITY] [IGNORE]
         [INTO] TBL_NAME [(COL_NAME,...)]
         SELECT ...
         [ ON DUPLICATE KEY UPDATE COL_NAME=EXPR, ... ]

With `INSERT ... SELECT', you can quickly insert many rows into a table
from one or many tables. For example:

     INSERT INTO tbl_temp2 (fld_id)
       SELECT tbl_temp1.fld_order_id
       FROM tbl_temp1 WHERE tbl_temp1.fld_order_id > 100;

The following conditions hold for a `INSERT ...  SELECT' statements:

   * Specify `IGNORE' to ignore rows that would cause duplicate-key
     violations.

   * `DELAYED' is ignored with `INSERT ... SELECT'.

   * The target table of the `INSERT' statement may appear in the
     `FROM' clause of the `SELECT' part of the query. (This was not
     possible in some older versions of MySQL.) In this case, MySQL
     creates a temporary table to hold the rows from the `SELECT' and
     then inserts those rows into the target table. However, it remains
     true that you cannot use `INSERT INTO t ... SELECT ... FROM t'
     when `t' is a `TEMPORARY' table, because `TEMPORARY' tables cannot
     be referred to twice in the same statement (see *Note
     temporary-table-problems::).

   * `AUTO_INCREMENT' columns work as usual.

   * To ensure that the binary log can be used to re-create the
     original tables, MySQL does not allow concurrent inserts for
     `INSERT ... SELECT' statements.

   * Currently, you cannot insert into a table and select from the same
     table in a subquery.

   * To avoid ambigious column reference problems when the `SELECT' and
     the `INSERT' refer to the same table, provide a unique alias for
     each table used in the `SELECT' part, and qualify column names in
     that part with the appropriate alias.

In the values part of `ON DUPLICATE KEY UPDATE', you can refer to
columns in other tables, as long as you do not use `GROUP BY' in the
`SELECT' part. One side effect is that you must qualify non-unique
column names in the values part.


File: manual.info,  Node: insert-delayed,  Next: insert-on-duplicate,  Prev: insert-select,  Up: insert

12.2.4.2 `INSERT DELAYED' Syntax
................................

     INSERT DELAYED ...

The `DELAYED' option for the `INSERT' statement is a MySQL extension to
standard SQL that is very useful if you have clients that cannot or
need not wait for the `INSERT' to complete.  This is a common situation
when you use MySQL for logging and you also periodically run `SELECT'
and `UPDATE' statements that take a long time to complete.

When a client uses `INSERT DELAYED', it gets an okay from the server at
once, and the row is queued to be inserted when the table is not in use
by any other thread.

Another major benefit of using `INSERT DELAYED' is that inserts from
many clients are bundled together and written in one block. This is
much faster than performing many separate inserts.

Note that `INSERT DELAYED' is slower than a normal `INSERT' if the
table is not otherwise in use. There is also the additional overhead
for the server to handle a separate thread for each table for which
there are delayed rows. This means that you should use `INSERT DELAYED'
only when you are really sure that you need it.

The queued rows are held only in memory until they are inserted into
the table. This means that if you terminate `mysqld' forcibly (for
example, with `kill -9') or if `mysqld' dies unexpectedly, _any queued
rows that have not been written to disk are lost_.

There are some constraints on the use of `DELAYED':

   * `INSERT DELAYED' works only with `MyISAM', `MEMORY', `ARCHIVE',
     and (as of MySQL 5.1.19) `BLACKHOLE' tables. See *Note
     myisam-storage-engine::, *Note memory-storage-engine::, *Note
     archive-storage-engine::, and *Note blackhole-storage-engine::.

   * For `MyISAM' tables, if there are no free blocks in the middle of
     the data file, concurrent `SELECT' and `INSERT' statements are
     supported. Under these circumstances, you very seldom need to use
     `INSERT DELAYED' with `MyISAM'.

   * `INSERT DELAYED' should be used only for `INSERT' statements that
     specify value lists. The server ignores `DELAYED' for `INSERT ...
     SELECT' or `INSERT ...  ON DUPLICATE KEY UPDATE' statements.

   * Because the `INSERT DELAYED' statement returns immediately, before
     the rows are inserted, you cannot use `LAST_INSERT_ID()' to get
     the `AUTO_INCREMENT' value that the statement might generate.

   * `DELAYED' rows are not visible to `SELECT' statements until they
     actually have been inserted.

   * `DELAYED' is ignored on slave replication servers, so that `INSERT
     DELAYED' is treated as a normal `INSERT' on slaves.  This is
     because `DELAYED' could cause the slave to have different data
     than the master.

   * Pending `INSERT DELAYED' statements are lost if a table is write
     locked and `ALTER TABLE' is used to modify the table structure.

   * `INSERT DELAYED' is not supported for views.

   * `INSERT DELAYED' is not supported for partitioned tables.

The following describes in detail what happens when you use the
`DELAYED' option to `INSERT' or `REPLACE'. In this description, the
`thread' is the thread that received an `INSERT DELAYED' statement and
`handler' is the thread that handles all `INSERT DELAYED' statements
for a particular table.

   * When a thread executes a `DELAYED' statement for a table, a
     handler thread is created to process all `DELAYED' statements for
     the table, if no such handler already exists.

   * The thread checks whether the handler has previously acquired a
     `DELAYED' lock; if not, it tells the handler thread to do so. The
     `DELAYED' lock can be obtained even if other threads have a `READ'
     or `WRITE' lock on the table. However, the handler waits for all
     `ALTER TABLE' locks or `FLUSH TABLES' statements to finish, to
     ensure that the table structure is up to date.

   * The thread executes the `INSERT' statement, but instead of writing
     the row to the table, it puts a copy of the final row into a queue
     that is managed by the handler thread. Any syntax errors are
     noticed by the thread and reported to the client program.

   * The client cannot obtain from the server the number of duplicate
     rows or the `AUTO_INCREMENT' value for the resulting row, because
     the `INSERT' returns before the insert operation has been
     completed. (If you use the C API, the *Note `mysql_info()':
     mysql-info. function does not return anything meaningful, for the
     same reason.)

   * The binary log is updated by the handler thread when the row is
     inserted into the table. In case of multiple-row inserts, the
     binary log is updated when the first row is inserted.

   * Each time that `delayed_insert_limit' rows are written, the
     handler checks whether any `SELECT' statements are still pending.
     If so, it allows these to execute before continuing.

   * When the handler has no more rows in its queue, the table is
     unlocked. If no new `INSERT DELAYED' statements are received within
     `delayed_insert_timeout' seconds, the handler terminates.

   * If more than `delayed_queue_size' rows are pending in a specific
     handler queue, the thread requesting `INSERT DELAYED' waits until
     there is room in the queue. This is done to ensure that `mysqld'
     does not use all memory for the delayed memory queue.

   * The handler thread shows up in the MySQL process list with
     `delayed_insert' in the `Command' column. It is killed if you
     execute a `FLUSH TABLES' statement or kill it with `KILL
     THREAD_ID'. However, before exiting, it first stores all queued
     rows into the table. During this time it does not accept any new
     `INSERT' statements from other threads. If you execute an `INSERT
     DELAYED' statement after this, a new handler thread is created.

     Note that this means that `INSERT DELAYED' statements have higher
     priority than normal `INSERT' statements if there is an `INSERT
     DELAYED' handler running. Other update statements have to wait
     until the `INSERT DELAYED' queue is empty, someone terminates the
     handler thread (with `KILL THREAD_ID'), or someone executes a
     `FLUSH TABLES'.

   * The following status variables provide information about `INSERT
     DELAYED' statements:

     *Status Variable*              *Meaning*
     `Delayed_insert_threads'       Number of handler threads
     `Delayed_writes'               Number of rows written with `INSERT
                                    DELAYED'
     `Not_flushed_delayed_rows'     Number of rows waiting to be written

     You can view these variables by issuing a `SHOW STATUS' statement
     or by executing a `mysqladmin extended-status' command.


File: manual.info,  Node: insert-on-duplicate,  Prev: insert-delayed,  Up: insert

12.2.4.3 `INSERT ... ON DUPLICATE KEY UPDATE' Syntax
....................................................

If you specify `ON DUPLICATE KEY UPDATE', and a row is inserted that
would cause a duplicate value in a `UNIQUE' index or `PRIMARY KEY', an
`UPDATE' of the old row is performed. For example, if column `a' is
declared as `UNIQUE' and contains the value `1', the following two
statements have identical effect:

     INSERT INTO table (a,b,c) VALUES (1,2,3)
       ON DUPLICATE KEY UPDATE c=c+1;

     UPDATE table SET c=c+1 WHERE a=1;

With `ON DUPLICATE KEY UPDATE', the affected-rows value per row is 1 if
the row is inserted as a new row and 2 if an existing row is updated.

If column `b' is also unique, the `INSERT' is equivalent to this
`UPDATE' statement instead:

     UPDATE table SET c=c+1 WHERE a=1 OR b=2 LIMIT 1;

If `a=1 OR b=2' matches several rows, only _one_ row is updated. In
general, you should try to avoid using an `ON DUPLICATE KEY' clause on
tables with multiple unique indexes.

The `ON DUPLICATE KEY UPDATE' clause can contain multiple column
assignments, separated by commas.

You can use the `VALUES(COL_NAME)' function in the `UPDATE' clause to
refer to column values from the `INSERT' portion of the `INSERT ...
UPDATE' statement. In other words, `VALUES(COL_NAME)' in the `UPDATE'
clause refers to the value of COL_NAME that would be inserted, had no
duplicate-key conflict occurred. This function is especially useful in
multiple-row inserts. The `VALUES()' function is meaningful only in
`INSERT ... UPDATE' statements and returns `NULL' otherwise. Example:

     INSERT INTO table (a,b,c) VALUES (1,2,3),(4,5,6)
       ON DUPLICATE KEY UPDATE c=VALUES(a)+VALUES(b);

That statement is identical to the following two statements:

     INSERT INTO table (a,b,c) VALUES (1,2,3)
       ON DUPLICATE KEY UPDATE c=3;
     INSERT INTO table (a,b,c) VALUES (4,5,6)
       ON DUPLICATE KEY UPDATE c=9;

If a table contains an `AUTO_INCREMENT' column and `INSERT ... UPDATE'
inserts a row, the `LAST_INSERT_ID()' function returns the
`AUTO_INCREMENT' value. If the statement updates a row instead,
`LAST_INSERT_ID()' is not meaningful. However, you can work around this
by using `LAST_INSERT_ID(EXPR)'.  Suppose that `id' is the
`AUTO_INCREMENT' column. To make `LAST_INSERT_ID()' meaningful for
updates, insert rows as follows:

     INSERT INTO table (a,b,c) VALUES (1,2,3)
       ON DUPLICATE KEY UPDATE id=LAST_INSERT_ID(id), c=3;

The `DELAYED' option is ignored when you use `ON DUPLICATE KEY UPDATE'.


File: manual.info,  Node: load-data,  Next: replace,  Prev: insert,  Up: sql-syntax-data-manipulation

12.2.5 `LOAD DATA INFILE' Syntax
--------------------------------

     LOAD DATA [LOW_PRIORITY | CONCURRENT] [LOCAL] INFILE 'FILE_NAME'
         [REPLACE | IGNORE]
         INTO TABLE TBL_NAME
         [CHARACTER SET CHARSET_NAME]
         [{FIELDS | COLUMNS}
             [TERMINATED BY 'STRING']
             [[OPTIONALLY] ENCLOSED BY 'CHAR']
             [ESCAPED BY 'CHAR']
         ]
         [LINES
             [STARTING BY 'STRING']
             [TERMINATED BY 'STRING']
         ]
         [IGNORE NUMBER LINES]
         [(COL_NAME_OR_USER_VAR,...)]
         [SET COL_NAME = EXPR,...]

The `LOAD DATA INFILE' statement reads rows from a text file into a
table at a very high speed. The filename must be given as a literal
string.

`LOAD DATA INFILE' is the complement of `SELECT ... INTO OUTFILE'. (See
*Note select::.) To write data from a table to a file, use `SELECT ...
INTO OUTFILE'. To read the file back into a table, use `LOAD DATA
INFILE'. The syntax of the `FIELDS' and `LINES' clauses is the same for
both statements.  Both clauses are optional, but `FIELDS' must precede
`LINES' if both are specified.

For more information about the efficiency of `INSERT' versus `LOAD DATA
INFILE' and speeding up `LOAD DATA INFILE', see *Note insert-speed::.

The character set indicated by the `character_set_database' system
variable is used to interpret the information in the file. `SET NAMES'
and the setting of `character_set_client' do not affect interpretation
of input. If the contents of the input file use a character set that
differs from the default, it is usually preferable to specify the
character set of the file by using the `CHARACTER SET' clause, which is
available as of MySQL 5.1.17.

`LOAD DATA INFILE' interprets all fields in the file as having the same
character set, regardless of the data types of the columns into which
field values are loaded. For proper interpretation of file contents,
you must ensure that it was written with the correct character set. For
example, if you write a data file with `mysqldump -T' or by issuing a
`SELECT ... INTO OUTFILE' statement in `mysql', be sure to use a
`--default-character-set' option with `mysqldump' or `mysql' so that
output is written in the character set to be used when the file is
loaded with `LOAD DATA INFILE'.

Note that it is currently not possible to load data files that use the
`ucs2' character set.

As of MySQL 5.1.6, the `character_set_filesystem' system variable
controls the interpretation of the filename.

You can also load data files by using the `mysqlimport' utility; it
operates by sending a `LOAD DATA INFILE' statement to the server. The
`--local' option causes `mysqlimport' to read data files from the client
host. You can specify the `--compress' option to get better performance
over slow networks if the client and server support the compressed
protocol. See *Note mysqlimport::.

If you use `LOW_PRIORITY', execution of the `LOAD DATA' statement is
delayed until no other clients are reading from the table. This affects
only storage engines that use only table-level locking (`MyISAM',
`MEMORY', `MERGE').

If you specify `CONCURRENT' with a `MyISAM' table that satisfies the
condition for concurrent inserts (that is, it contains no free blocks
in the middle), other threads can retrieve data from the table while
`LOAD DATA' is executing. Using this option affects the performance of
`LOAD DATA' a bit, even if no other thread is using the table at the
same time.

`CONCURRENT' is not replicated when using statement-based replication;
however, it is replicated when using row-based replication. See *Note
replication-features-load-data::, for more information.

*Note*:

Prior to MySQL 5.1.23, `LOAD DATA' performed very poorly when importing
into partitioned tables. The statement now uses buffering to improve
performance; however, the buffer uses 130 KB memory per partition to
achieve this.  (Bug#26527 (http://bugs.mysql.com/26527))

The `LOCAL' keyword, if specified, is interpreted with respect to the
client end of the connection:

   * If `LOCAL' is specified, the file is read by the client program on
     the client host and sent to the server.  The file can be given as
     a full pathname to specify its exact location. If given as a
     relative pathname, the name is interpreted relative to the
     directory in which the client program was started.

   * If `LOCAL' is not specified, the file must be located on the
     server host and is read directly by the server.  The server uses
     the following rules to locate the file:

        * If the filename is an absolute pathname, the server uses it
          as given.

        * If the filename is a relative pathname with one or more
          leading components, the server searches for the file relative
          to the server's data directory.

        * If a filename with no leading components is given, the server
          looks for the file in the database directory of the default
          database.

Note that, in the non-`LOCAL' case, these rules mean that a file named
as `./myfile.txt' is read from the server's data directory, whereas the
file named as `myfile.txt' is read from the database directory of the
default database. For example, if `db1' is the default database, the
following `LOAD DATA' statement reads the file `data.txt' from the
database directory for `db1', even though the statement explicitly loads
the file into a table in the `db2' database:

     LOAD DATA INFILE 'data.txt' INTO TABLE db2.my_table;

Windows pathnames are specified using forward slashes rather than
backslashes. If you do use backslashes, you must double them.

For security reasons, when reading text files located on the server,
the files must either reside in the database directory or be readable
by all. Also, to use `LOAD DATA INFILE' on server files, you must have
the `FILE' privilege. See *Note privileges-provided::.

Using `LOCAL' is a bit slower than letting the server access the files
directly, because the contents of the file must be sent over the
connection by the client to the server. On the other hand, you do not
need the `FILE' privilege to load local files.

With `LOCAL', the default behavior is the same as if `IGNORE' is
specified; this is because the server has no way to stop transmission
of the file in the middle of the operation. `IGNORE' is explained
further later in this section.

`LOCAL' works only if your server and your client both have been
enabled to allow it. For example, if `mysqld' was started with
`--local-infile=0', `LOCAL' does not work. See *Note load-data-local::.

On Unix, if you need `LOAD DATA' to read from a pipe, you can use the
following technique (here we load the listing of the `/' directory into
a table):

     mkfifo /mysql/db/x/x
     chmod 666 /mysql/db/x/x
     find / -ls > /mysql/db/x/x &
     mysql -e "LOAD DATA INFILE 'x' INTO TABLE x" x

Note that you must run the command that generates the data to be loaded
and the `mysql' commands either on separate terminals, or run the data
generation process in the background (as shown in the preceding
example). If you do not do this, the pipe will block until data is read
by the `mysql' process.

The `REPLACE' and `IGNORE' keywords control handling of input rows that
duplicate existing rows on unique key values:

   * If you specify `REPLACE', input rows replace existing rows. In
     other words, rows that have the same value for a primary key or
     unique index as an existing row. See *Note replace::.

   * If you specify `IGNORE', input rows that duplicate an existing row
     on a unique key value are skipped.  If you do not specify either
     option, the behavior depends on whether the `LOCAL' keyword is
     specified.  Without `LOCAL', an error occurs when a duplicate key
     value is found, and the rest of the text file is ignored. With
     `LOCAL', the default behavior is the same as if `IGNORE' is
     specified; this is because the server has no way to stop
     transmission of the file in the middle of the operation.

If you want to ignore foreign key constraints during the load
operation, you can issue a `SET FOREIGN_KEY_CHECKS=0' statement before
executing `LOAD DATA'.

If you use `LOAD DATA INFILE' on an empty `MyISAM' table, all
non-unique indexes are created in a separate batch (as for `REPAIR
TABLE'). Normally, this makes `LOAD DATA INFILE' much faster when you
have many indexes. In some extreme cases, you can create the indexes
even faster by turning them off with `ALTER TABLE ... DISABLE KEYS'
before loading the file into the table and using `ALTER TABLE ...
ENABLE KEYS' to re-create the indexes after loading the file. See *Note
insert-speed::.

For both the `LOAD DATA INFILE' and `SELECT ... INTO OUTFILE'
statements, the syntax of the `FIELDS' and `LINES' clauses is the same.
Both clauses are optional, but `FIELDS' must precede `LINES' if both
are specified.

If you specify a `FIELDS' clause, each of its subclauses (`TERMINATED
BY', `[OPTIONALLY] ENCLOSED BY', and `ESCAPED BY') is also optional,
except that you must specify at least one of them.

If you specify no `FIELDS' clause, the defaults are the same as if you
had written this:

     FIELDS TERMINATED BY '\t' ENCLOSED BY '' ESCAPED BY '\\'

If you specify no `LINES' clause, the defaults are the same as if you
had written this:

     LINES TERMINATED BY '\n' STARTING BY ''

In other words, the defaults cause `LOAD DATA INFILE' to act as follows
when reading input:

   * Look for line boundaries at newlines.

   * Do not skip over any line prefix.

   * Break lines into fields at tabs.

   * Do not expect fields to be enclosed within any quoting characters.

   * Interpret occurrences of tab, newline, or ``\'' preceded by ``\''
     as literal characters that are part of field values.

Conversely, the defaults cause `SELECT ... INTO OUTFILE' to act as
follows when writing output:

   * Write tabs between fields.

   * Do not enclose fields within any quoting characters.

   * Use ``\'' to escape instances of tab, newline, or ``\'' that occur
     within field values.

   * Write newlines at the ends of lines.

Backslash is the MySQL escape character within strings, so to write
`FIELDS ESCAPED BY '\\'', you must specify two backslashes for the
value to be interpreted as a single backslash.

*Note*:

If you have generated the text file on a Windows system, you might have
to use `LINES TERMINATED BY '\r\n'' to read the file properly, because
Windows programs typically use two characters as a line terminator.
Some programs, such as `WordPad', might use `\r' as a line terminator
when writing files. To read such files, use `LINES TERMINATED BY '\r''.

If all the lines you want to read in have a common prefix that you want
to ignore, you can use `LINES STARTING BY 'PREFIX_STRING'' to skip over
the prefix, _and anything before it_. If a line does not include the
prefix, the entire line is skipped. Suppose that you issue the
following statement:

     LOAD DATA INFILE '/tmp/test.txt' INTO TABLE test
       FIELDS TERMINATED BY ','  LINES STARTING BY 'xxx';

If the data file looks like this:

     xxx"abc",1
     something xxx"def",2
     "ghi",3

The resulting rows will be `("abc",1)' and `("def",2)'. The third row
in the file is skipped because it does not contain the prefix.

The `IGNORE NUMBER LINES' option can be used to ignore lines at the
start of the file. For example, you can use `IGNORE 1 LINES' to skip
over an initial header line containing column names:

     LOAD DATA INFILE '/tmp/test.txt' INTO TABLE test IGNORE 1 LINES;

When you use `SELECT ... INTO OUTFILE' in tandem with `LOAD DATA
INFILE' to write data from a database into a file and then read the
file back into the database later, the field- and line-handling options
for both statements must match. Otherwise, `LOAD DATA INFILE' will not
interpret the contents of the file properly. Suppose that you use
`SELECT ... INTO OUTFILE' to write a file with fields delimited by
commas:

     SELECT * INTO OUTFILE 'data.txt'
       FIELDS TERMINATED BY ','
       FROM table2;

To read the comma-delimited file back in, the correct statement would
be:

     LOAD DATA INFILE 'data.txt' INTO TABLE table2
       FIELDS TERMINATED BY ',';

If instead you tried to read in the file with the statement shown
following, it wouldn't work because it instructs `LOAD DATA INFILE' to
look for tabs between fields:

     LOAD DATA INFILE 'data.txt' INTO TABLE table2
       FIELDS TERMINATED BY '\t';

The likely result is that each input line would be interpreted as a
single field.

`LOAD DATA INFILE' can be used to read files obtained from external
sources. For example, many programs can export data in comma-separated
values (CSV) format, such that lines have fields separated by commas
and enclosed within double quotes. If lines in such a file are
terminated by newlines, the statement shown here illustrates the field-
and line-handling options you would use to load the file:

     LOAD DATA INFILE 'data.txt' INTO TABLE TBL_NAME
       FIELDS TERMINATED BY ',' ENCLOSED BY '"'
       LINES TERMINATED BY '\n';

If the input values are not necessarily enclosed within quotes, use
`OPTIONALLY' before the `ENCLOSED BY' keywords.

Any of the field- or line-handling options can specify an empty string
(`'''). If not empty, the `FIELDS [OPTIONALLY] ENCLOSED BY' and `FIELDS
ESCAPED BY' values must be a single character. The `FIELDS TERMINATED
BY', `LINES STARTING BY', and `LINES TERMINATED BY' values can be more
than one character. For example, to write lines that are terminated by
carriage return/linefeed pairs, or to read a file containing such
lines, specify a `LINES TERMINATED BY '\r\n'' clause.

To read a file containing jokes that are separated by lines consisting
of `%%', you can do this

     CREATE TABLE jokes
       (a INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
       joke TEXT NOT NULL);
     LOAD DATA INFILE '/tmp/jokes.txt' INTO TABLE jokes
       FIELDS TERMINATED BY ''
       LINES TERMINATED BY '\n%%\n' (joke);

`FIELDS [OPTIONALLY] ENCLOSED BY' controls quoting of fields. For
output (`SELECT ... INTO OUTFILE'), if you omit the word `OPTIONALLY',
all fields are enclosed by the `ENCLOSED BY' character. An example of
such output (using a comma as the field delimiter) is shown here:

     "1","a string","100.20"
     "2","a string containing a , comma","102.20"
     "3","a string containing a \" quote","102.20"
     "4","a string containing a \", quote and comma","102.20"

If you specify `OPTIONALLY', the `ENCLOSED BY' character is used only
to enclose values from columns that have a string data type (such as
`CHAR', `BINARY', `TEXT', or `ENUM'):

     1,"a string",100.20
     2,"a string containing a , comma",102.20
     3,"a string containing a \" quote",102.20
     4,"a string containing a \", quote and comma",102.20

Note that occurrences of the `ENCLOSED BY' character within a field
value are escaped by prefixing them with the `ESCAPED BY' character.
Also note that if you specify an empty `ESCAPED BY' value, it is
possible to inadvertently generate output that cannot be read properly
by `LOAD DATA INFILE'. For example, the preceding output just shown
would appear as follows if the escape character is empty. Observe that
the second field in the fourth line contains a comma following the
quote, which (erroneously) appears to terminate the field:

     1,"a string",100.20
     2,"a string containing a , comma",102.20
     3,"a string containing a " quote",102.20
     4,"a string containing a ", quote and comma",102.20

For input, the `ENCLOSED BY' character, if present, is stripped from
the ends of field values. (This is true regardless of whether
`OPTIONALLY' is specified; `OPTIONALLY' has no effect on input
interpretation.) Occurrences of the `ENCLOSED BY' character preceded by
the `ESCAPED BY' character are interpreted as part of the current field
value.

If the field begins with the `ENCLOSED BY' character, instances of that
character are recognized as terminating a field value only if followed
by the field or line `TERMINATED BY' sequence. To avoid ambiguity,
occurrences of the `ENCLOSED BY' character within a field value can be
doubled and are interpreted as a single instance of the character. For
example, if `ENCLOSED BY '"'' is specified, quotes are handled as shown
here:

     "The ""BIG"" boss"  -> The "BIG" boss
     The "BIG" boss      -> The "BIG" boss
     The ""BIG"" boss    -> The ""BIG"" boss

`FIELDS ESCAPED BY' controls how to write or read special characters.
If the `FIELDS ESCAPED BY' character is not empty, it is used to prefix
the following characters on output:

   * The `FIELDS ESCAPED BY' character

   * The `FIELDS [OPTIONALLY] ENCLOSED BY' character

   * The first character of the `FIELDS TERMINATED BY' and `LINES
     TERMINATED BY' values

   * ASCII `0' (what is actually written following the escape character
     is ASCII ``0'', not a zero-valued byte)

If the `FIELDS ESCAPED BY' character is empty, no characters are
escaped and `NULL' is output as `NULL', not `\N'. It is probably not a
good idea to specify an empty escape character, particularly if field
values in your data contain any of the characters in the list just
given.

For input, if the `FIELDS ESCAPED BY' character is not empty,
occurrences of that character are stripped and the following character
is taken literally as part of a field value.  Some two-character
sequences that are exceptions, where the first character is the escape
character. These sequences are shown in the following table (using
``\'' for the escape character). The rules for `NULL' handling are
described later in this section.

`\0'    An ASCII 0 (`NUL') character
`\b'    A backspace character
`\n'    A newline (linefeed) character
`\r'    A carriage return character
`\t'    A tab character.
`\Z'    ASCII 26 (Control-Z)
`\N'    NULL

For more information about ``\''-escape syntax, see *Note literals::.

In certain cases, field- and line-handling options interact:

   * If `LINES TERMINATED BY' is an empty string and `FIELDS TERMINATED
     BY' is non-empty, lines are also terminated with `FIELDS TERMINATED
     BY'.

   * If the `FIELDS TERMINATED BY' and `FIELDS ENCLOSED BY' values are
     both empty (`'''), a fixed-row (non-delimited) format is used.
     With fixed-row format, no delimiters are used between fields (but
     you can still have a line terminator). Instead, column values are
     read and written using a field width wide enough to hold all
     values in the field. For `TINYINT', `SMALLINT', `MEDIUMINT',
     `INT', and `BIGINT', the field widths are 4, 6, 8, 11, and 20,
     respectively, no matter what the declared display width is.

     `LINES TERMINATED BY' is still used to separate lines. If a line
     does not contain all fields, the rest of the columns are set to
     their default values. If you do not have a line terminator, you
     should set this to `'''. In this case, the text file must contain
     all fields for each row.

     Fixed-row format also affects handling of `NULL' values, as
     described later. Note that fixed-size format does not work if you
     are using a multi-byte character set.

Handling of `NULL' values varies according to the `FIELDS' and `LINES'
options in use:

   * For the default `FIELDS' and `LINES' values, `NULL' is written as
     a field value of `\N' for output, and a field value of `\N' is
     read as `NULL' for input (assuming that the `ESCAPED BY' character
     is ``\'').

   * If `FIELDS ENCLOSED BY' is not empty, a field containing the
     literal word `NULL' as its value is read as a `NULL' value. This
     differs from the word `NULL' enclosed within `FIELDS ENCLOSED BY'
     characters, which is read as the string `'NULL''.

   * If `FIELDS ESCAPED BY' is empty, `NULL' is written as the word
     `NULL'.

   * With fixed-row format (which is used when `FIELDS TERMINATED BY'
     and `FIELDS ENCLOSED BY' are both empty), `NULL' is written as an
     empty string. Note that this causes both `NULL' values and empty
     strings in the table to be indistinguishable when written to the
     file because both are written as empty strings. If you need to be
     able to tell the two apart when reading the file back in, you
     should not use fixed-row format.

An attempt to load `NULL' into a `NOT NULL' column causes assignment of
the implicit default value for the column's data type and a warning, or
an error in strict SQL mode. Implicit default values are discussed in
*Note data-type-defaults::.

Some cases are not supported by `LOAD DATA INFILE':

   * Fixed-size rows (`FIELDS TERMINATED BY' and `FIELDS ENCLOSED BY'
     both empty) and `BLOB' or `TEXT' columns.

   * If you specify one separator that is the same as or a prefix of
     another, `LOAD DATA INFILE' cannot interpret the input properly.
     For example, the following `FIELDS' clause would cause problems:

          FIELDS TERMINATED BY '"' ENCLOSED BY '"'

   * If `FIELDS ESCAPED BY' is empty, a field value that contains an
     occurrence of `FIELDS ENCLOSED BY' or `LINES TERMINATED BY'
     followed by the `FIELDS TERMINATED BY' value causes `LOAD DATA
     INFILE' to stop reading a field or line too early. This happens
     because `LOAD DATA INFILE' cannot properly determine where the
     field or line value ends.

The following example loads all columns of the `persondata' table:

     LOAD DATA INFILE 'persondata.txt' INTO TABLE persondata;

By default, when no column list is provided at the end of the `LOAD
DATA INFILE' statement, input lines are expected to contain a field for
each table column. If you want to load only some of a table's columns,
specify a column list:

     LOAD DATA INFILE 'persondata.txt' INTO TABLE persondata (col1,col2,...);

You must also specify a column list if the order of the fields in the
input file differs from the order of the columns in the table.
Otherwise, MySQL cannot tell how to match input fields with table
columns.

The column list can contain either column names or user variables.
With user variables, the `SET' clause enables you to perform
transformations on their values before assigning the result to columns.

User variables in the `SET' clause can be used in several ways. The
following example uses the first input column directly for the value of
`t1.column1', and assigns the second input column to a user variable
that is subjected to a division operation before being used for the
value of `t1.column2':

     LOAD DATA INFILE 'file.txt'
       INTO TABLE t1
       (column1, @var1)
       SET column2 = @var1/100;

The `SET' clause can be used to supply values not derived from the
input file. The following statement sets `column3' to the current date
and time:

     LOAD DATA INFILE 'file.txt'
       INTO TABLE t1
       (column1, column2)
       SET column3 = CURRENT_TIMESTAMP;

You can also discard an input value by assigning it to a user variable
and not assigning the variable to a table column:

     LOAD DATA INFILE 'file.txt'
       INTO TABLE t1
       (column1, @dummy, column2, @dummy, column3);

Use of the column/variable list and `SET' clause is subject to the
following restrictions:

   * Assignments in the `SET' clause should have only column names on
     the left hand side of assignment operators.

   * You can use subqueries in the right hand side of `SET'
     assignments. A subquery that returns a value to be assigned to a
     column may be a scalar subquery only. Also, you cannot use a
     subquery to select from the table that is being loaded.

   * Lines ignored by an `IGNORE' clause are not processed for the
     column/variable list or `SET' clause.

   * User variables cannot be used when loading data with fixed-row
     format because user variables do not have a display width.

When processing an input line, `LOAD DATA' splits it into fields and
uses the values according to the column/variable list and the `SET'
clause, if they are present. Then the resulting row is inserted into the
table. If there are `BEFORE INSERT' or `AFTER INSERT' triggers for the
table, they are activated before or after inserting the row,
respectively.

If an input line has too many fields, the extra fields are ignored and
the number of warnings is incremented.

If an input line has too few fields, the table columns for which input
fields are missing are set to their default values. Default value
assignment is described in *Note data-type-defaults::.

An empty field value is interpreted differently than if the field value
is missing:

   * For string types, the column is set to the empty string.

   * For numeric types, the column is set to `0'.

   * For date and time types, the column is set to the appropriate
     `zero' value for the type. See *Note date-and-time-types::.

These are the same values that result if you assign an empty string
explicitly to a string, numeric, or date or time type explicitly in an
`INSERT' or `UPDATE' statement.

`TIMESTAMP' columns are set to the current date and time only if there
is a `NULL' value for the column (that is, `\N') and the column is not
declared to allow `NULL' values, or if the `TIMESTAMP' column's default
value is the current timestamp and it is omitted from the field list
when a field list is specified.

`LOAD DATA INFILE' regards all input as strings, so you cannot use
numeric values for `ENUM' or `SET' columns the way you can with
`INSERT' statements. All `ENUM' and `SET' values must be specified as
strings.

`BIT' values cannot be loaded using binary notation (for example,
`b'011010''). To work around this, specify the values as regular
integers and use the `SET' clause to convert them so that MySQL
performs a numeric type conversion and loads them into the `BIT' column
properly:

     shell> cat /tmp/bit_test.txt
     2
     127
     shell> mysql test
     mysql> LOAD DATA INFILE '/tmp/bit_test.txt'
         -> INTO TABLE bit_test (@var1) SET b= CAST(@var1 AS UNSIGNED);
     Query OK, 2 rows affected (0.00 sec)
     Records: 2  Deleted: 0  Skipped: 0  Warnings: 0

     mysql> SELECT BIN(b+0) FROM bit_test;
     +----------+
     | bin(b+0) |
     +----------+
     | 10       |
     | 1111111  |
     +----------+
     2 rows in set (0.00 sec)

When the `LOAD DATA INFILE' statement finishes, it returns an
information string in the following format:

     Records: 1  Deleted: 0  Skipped: 0  Warnings: 0

If you are using the C API, you can get information about the statement
by calling the *Note `mysql_info()': mysql-info. function. See *Note
mysql-info::.

Warnings occur under the same circumstances as when values are inserted
via the `INSERT' statement (see *Note insert::), except that `LOAD DATA
INFILE' also generates warnings when there are too few or too many
fields in the input row. The warnings are not stored anywhere; the
number of warnings can be used only as an indication of whether
everything went well.

You can use `SHOW WARNINGS' to get a list of the first
`max_error_count' warnings as information about what went wrong. See
*Note show-warnings::.


File: manual.info,  Node: replace,  Next: select,  Prev: load-data,  Up: sql-syntax-data-manipulation

12.2.6 `REPLACE' Syntax
-----------------------

     REPLACE [LOW_PRIORITY | DELAYED]
         [INTO] TBL_NAME [(COL_NAME,...)]
         {VALUES | VALUE} ({EXPR | DEFAULT},...),(...),...

Or:

     REPLACE [LOW_PRIORITY | DELAYED]
         [INTO] TBL_NAME
         SET COL_NAME={EXPR | DEFAULT}, ...

Or:

     REPLACE [LOW_PRIORITY | DELAYED]
         [INTO] TBL_NAME [(COL_NAME,...)]
         SELECT ...

`REPLACE' works exactly like `INSERT', except that if an old row in the
table has the same value as a new row for a `PRIMARY KEY' or a `UNIQUE'
index, the old row is deleted before the new row is inserted. See *Note
insert::.

`REPLACE' is a MySQL extension to the SQL standard. It either inserts,
or _deletes_ and inserts. For another MySQL extension to standard SQL
-- that either inserts or _updates_ -- see *Note insert-on-duplicate::.

Note that unless the table has a `PRIMARY KEY' or `UNIQUE' index, using
a `REPLACE' statement makes no sense. It becomes equivalent to
`INSERT', because there is no index to be used to determine whether a
new row duplicates another.

Values for all columns are taken from the values specified in the
`REPLACE' statement. Any missing columns are set to their default
values, just as happens for `INSERT'. You cannot refer to values from
the current row and use them in the new row. If you use an assignment
such as `SET COL_NAME = COL_NAME + 1', the reference to the column name
on the right hand side is treated as `DEFAULT(COL_NAME)', so the
assignment is equivalent to `SET COL_NAME = DEFAULT(COL_NAME) + 1'.

To use `REPLACE', you must have both the `INSERT' and `DELETE'
privileges for the table.

The `REPLACE' statement returns a count to indicate the number of rows
affected. This is the sum of the rows deleted and inserted. If the
count is 1 for a single-row `REPLACE', a row was inserted and no rows
were deleted. If the count is greater than 1, one or more old rows were
deleted before the new row was inserted. It is possible for a single
row to replace more than one old row if the table contains multiple
unique indexes and the new row duplicates values for different old rows
in different unique indexes.

The affected-rows count makes it easy to determine whether `REPLACE'
only added a row or whether it also replaced any rows: Check whether
the count is 1 (added) or greater (replaced).

If you are using the C API, the affected-rows count can be obtained
using the *Note `mysql_affected_rows()': mysql-affected-rows. function.

Currently, you cannot replace into a table and select from the same
table in a subquery.

MySQL uses the following algorithm for `REPLACE' (and `LOAD DATA ...
REPLACE'):

  1. Try to insert the new row into the table

  2. While the insertion fails because a duplicate-key error occurs for
     a primary key or unique index:

       1. Delete from the table the conflicting row that has the
          duplicate key value

       2. Try again to insert the new row into the table


File: manual.info,  Node: select,  Next: subqueries,  Prev: replace,  Up: sql-syntax-data-manipulation

12.2.7 `SELECT' Syntax
----------------------

* Menu:

* join::                         `JOIN' Syntax
* index-hints::                  Index Hint Syntax
* union::                        `UNION' Syntax

     SELECT
         [ALL | DISTINCT | DISTINCTROW ]
           [HIGH_PRIORITY]
           [STRAIGHT_JOIN]
           [SQL_SMALL_RESULT] [SQL_BIG_RESULT] [SQL_BUFFER_RESULT]
           [SQL_CACHE | SQL_NO_CACHE] [SQL_CALC_FOUND_ROWS]
         SELECT_EXPR, ...
         [FROM TABLE_REFERENCES
         [WHERE WHERE_CONDITION]
         [GROUP BY {COL_NAME | EXPR | POSITION}
           [ASC | DESC], ... [WITH ROLLUP]]
         [HAVING WHERE_CONDITION]
         [ORDER BY {COL_NAME | EXPR | POSITION}
           [ASC | DESC], ...]
         [LIMIT {[OFFSET,] ROW_COUNT | ROW_COUNT OFFSET OFFSET}]
         [PROCEDURE PROCEDURE_NAME(ARGUMENT_LIST)]
         [INTO OUTFILE 'FILE_NAME' EXPORT_OPTIONS
           | INTO DUMPFILE 'FILE_NAME'
           | INTO VAR_NAME [, VAR_NAME]]
         [FOR UPDATE | LOCK IN SHARE MODE]]

`SELECT' is used to retrieve rows selected from one or more tables, and
can include `UNION' statements and subqueries. See *Note union::, and
*Note subqueries::.

The most commonly used clauses of `SELECT' statements are these:

   * Each SELECT_EXPR indicates a column that you want to retrieve.
     There must be at least one SELECT_EXPR.

   * TABLE_REFERENCES indicates the table or tables from which to
     retrieve rows. Its syntax is described in *Note join::.

   * The `WHERE' clause, if given, indicates the condition or
     conditions that rows must satisfy to be selected.  WHERE_CONDITION
     is an expression that evaluates to true for each row to be
     selected. The statement selects all rows if there is no `WHERE'
     clause.

     In the `WHERE' clause, you can use any of the functions and
     operators that MySQL supports, except for aggregate (summary)
     functions. See *Note functions::.

`SELECT' can also be used to retrieve rows computed without reference
to any table.

For example:

     mysql> SELECT 1 + 1;
             -> 2

You are allowed to specify `DUAL' as a dummy table name in situations
where no tables are referenced:

     mysql> SELECT 1 + 1 FROM DUAL;
             -> 2

`DUAL' is purely for the convenience of people who require that all
`SELECT' statements should have `FROM' and possibly other clauses.
MySQL may ignore the clauses. MySQL does not require `FROM DUAL' if no
tables are referenced.

In general, clauses used must be given in exactly the order shown in
the syntax description. For example, a `HAVING' clause must come after
any `GROUP BY' clause and before any `ORDER BY' clause. The exception
is that the `INTO' clause can appear either as shown in the syntax
description or immediately following the SELECT_EXPR list.

   * A SELECT_EXPR can be given an alias using `AS ALIAS_NAME'. The
     alias is used as the expression's column name and can be used in
     `GROUP BY', `ORDER BY', or `HAVING' clauses. For example:

          SELECT CONCAT(last_name,', ',first_name) AS full_name
            FROM mytable ORDER BY full_name;

     The `AS' keyword is optional when aliasing a SELECT_EXPR. The
     preceding example could have been written like this:

          SELECT CONCAT(last_name,', ',first_name) full_name
            FROM mytable ORDER BY full_name;

     However, because the `AS' is optional, a subtle problem can occur
     if you forget the comma between two SELECT_EXPR expressions: MySQL
     interprets the second as an alias name. For example, in the
     following statement, `columnb' is treated as an alias name:

          SELECT columna columnb FROM mytable;

     For this reason, it is good practice to be in the habit of using
     `AS' explicitly when specifying column aliases.

     It is not allowable to refer to a column alias in a `WHERE'
     clause, because the column value might not yet be determined when
     the `WHERE' clause is executed. See *Note problems-with-alias::.

   * The `FROM TABLE_REFERENCES' clause indicates the table or tables
     from which to retrieve rows. If you name more than one table, you
     are performing a join. For information on join syntax, see *Note
     join::. For each table specified, you can optionally specify an
     alias.

          TBL_NAME [[AS] ALIAS] [INDEX_HINT]

     The use of index hints provides the optimizer with information
     about how to choose indexes during query processing. For a
     description of the syntax for specifying these hints, see *Note
     index-hints::.

     You can use `SET max_seeks_for_key=VALUE' as an alternative way to
     force MySQL to prefer key scans instead of table scans. See *Note
     server-system-variables::.

   * You can refer to a table within the default database as TBL_NAME,
     or as DB_NAME.TBL_NAME to specify a database explicitly. You can
     refer to a column as COL_NAME, TBL_NAME.COL_NAME, or
     DB_NAME.TBL_NAME.COL_NAME.  You need not specify a TBL_NAME or
     DB_NAME.TBL_NAME prefix for a column reference unless the
     reference would be ambiguous. See *Note identifier-qualifiers::,
     for examples of ambiguity that require the more explicit column
     reference forms.

   * A table reference can be aliased using `TBL_NAME AS ALIAS_NAME' or
     TBL_NAME ALIAS_NAME:

          SELECT t1.name, t2.salary FROM employee AS t1, info AS t2
            WHERE t1.name = t2.name;

          SELECT t1.name, t2.salary FROM employee t1, info t2
            WHERE t1.name = t2.name;

   * Columns selected for output can be referred to in `ORDER BY' and
     `GROUP BY' clauses using column names, column aliases, or column
     positions. Column positions are integers and begin with 1:

          SELECT college, region, seed FROM tournament
            ORDER BY region, seed;

          SELECT college, region AS r, seed AS s FROM tournament
            ORDER BY r, s;

          SELECT college, region, seed FROM tournament
            ORDER BY 2, 3;

     To sort in reverse order, add the `DESC' (descending) keyword to
     the name of the column in the `ORDER BY' clause that you are
     sorting by.  The default is ascending order; this can be specified
     explicitly using the `ASC' keyword.

     If `ORDER BY' occurs within a subquery and also is applied in the
     outer query, the outermost `ORDER BY' takes precedence. For
     example, results for the following statement are sorted in
     descending order, not ascending order:

          (SELECT ... ORDER BY a) ORDER BY a DESC;

     Use of column positions is deprecated because the syntax has been
     removed from the SQL standard.

   * If you use `GROUP BY', output rows are sorted according to the
     `GROUP BY' columns as if you had an `ORDER BY' for the same
     columns. To avoid the overhead of sorting that `GROUP BY'
     produces, add `ORDER BY NULL':

          SELECT a, COUNT(b) FROM test_table GROUP BY a ORDER BY NULL;

   * MySQL extends the `GROUP BY' clause so that you can also specify
     `ASC' and `DESC' after columns named in the clause:

          SELECT a, COUNT(b) FROM test_table GROUP BY a DESC;

   * MySQL extends the use of `GROUP BY' to allow selecting fields that
     are not mentioned in the `GROUP BY' clause. If you are not getting
     the results that you expect from your query, please read the
     description of `GROUP BY' found in *Note
     group-by-functions-and-modifiers::.

   * `GROUP BY' allows a `WITH ROLLUP' modifier. See *Note
     group-by-modifiers::.

   * The `HAVING' clause is applied nearly last, just before items are
     sent to the client, with no optimization. (`LIMIT' is applied after
     `HAVING'.)

     The SQL standard requires that `HAVING' must reference only
     columns in the `GROUP BY' clause or columns used in aggregate
     functions. However, MySQL supports an extension to this behavior,
     and allows `HAVING' to refer to columns in the `SELECT' list and
     columns in outer subqueries as well.

     If the `HAVING' clause refers to a column that is ambiguous, a
     warning occurs. In the following statement, `col2' is ambiguous
     because it is used as both an alias and a column name:

          SELECT COUNT(col1) AS col2 FROM t GROUP BY col2 HAVING col2 = 2;

     Preference is given to standard SQL behavior, so if a `HAVING'
     column name is used both in `GROUP BY' and as an aliased column in
     the output column list, preference is given to the column in the
     `GROUP BY' column.

   * Do not use `HAVING' for items that should be in the `WHERE'
     clause. For example, do not write the following:

          SELECT COL_NAME FROM TBL_NAME HAVING COL_NAME > 0;

     Write this instead:

          SELECT COL_NAME FROM TBL_NAME WHERE COL_NAME > 0;

   * The `HAVING' clause can refer to aggregate functions, which the
     `WHERE' clause cannot:

          SELECT user, MAX(salary) FROM users
            GROUP BY user HAVING MAX(salary) > 10;

     (This did not work in some older versions of MySQL.)

   * MySQL allows duplicate column names. That is, there can be more
     than one SELECT_EXPR with the same name. This is an extension to
     standard SQL. Because MySQL also allows `GROUP BY' and `HAVING' to
     refer to SELECT_EXPR values, this can result in an ambiguity:

          SELECT 12 AS a, a FROM t GROUP BY a;

     In that statement, both columns have the name `a'. To ensure that
     the correct column is used for grouping, use different names for
     each SELECT_EXPR.

   * MySQL resolves unqualified column or alias references in `ORDER
     BY' clauses by searching in the SELECT_EXPR values, then in the
     columns of the tables in the `FROM' clause.  For `GROUP BY' or
     `HAVING' clauses, it searches the `FROM' clause before searching
     in the SELECT_EXPR values. (For `GROUP BY' and `HAVING', this
     differs from the pre-MySQL 5.0 behavior that used the same rules
     as for `ORDER BY'.)

   * The `LIMIT' clause can be used to constrain the number of rows
     returned by the `SELECT' statement. `LIMIT' takes one or two
     numeric arguments, which must both be non-negative integer
     constants (except when using prepared statements).

     With two arguments, the first argument specifies the offset of the
     first row to return, and the second specifies the maximum number
     of rows to return. The offset of the initial row is 0 (not 1):

          SELECT * FROM tbl LIMIT 5,10;  # Retrieve rows 6-15

     To retrieve all rows from a certain offset up to the end of the
     result set, you can use some large number for the second
     parameter. This statement retrieves all rows from the 96th row to
     the last:

          SELECT * FROM tbl LIMIT 95,18446744073709551615;

     With one argument, the value specifies the number of rows to
     return from the beginning of the result set:

          SELECT * FROM tbl LIMIT 5;     # Retrieve first 5 rows

     In other words, `LIMIT ROW_COUNT' is equivalent to `LIMIT 0,
     ROW_COUNT'.

     For prepared statements, you can use placeholders. The following
     statements will return one row from the `tbl' table:

          SET @a=1;
          PREPARE STMT FROM 'SELECT * FROM tbl LIMIT ?';
          EXECUTE STMT USING @a;

     The following statements will return the second to sixth row from
     the `tbl' table:

          SET @skip=1; SET @numrows=5;
          PREPARE STMT FROM 'SELECT * FROM tbl LIMIT ?, ?';
          EXECUTE STMT USING @skip, @numrows;

     For compatibility with PostgreSQL, MySQL also supports the `LIMIT
     ROW_COUNT OFFSET OFFSET' syntax.

     If `LIMIT' occurs within a subquery and also is applied in the
     outer query, the outermost `LIMIT' takes precedence. For example,
     the following statement produces two rows, not one:

          (SELECT ... LIMIT 1) LIMIT 2;

   * A `PROCEDURE' clause names a procedure that should process the
     data in the result set. For an example, see *Note
     procedure-analyse::.

   * The `SELECT ... INTO OUTFILE 'FILE_NAME'' form of `SELECT' writes
     the selected rows to a file.  The file is created on the server
     host, so you must have the `FILE' privilege to use this syntax.
     FILE_NAME cannot be an existing file, which among other things
     prevents files such as `/etc/passwd' and database tables from
     being destroyed. As of MySQL 5.1.6, the `character_set_filesystem'
     system variable controls the interpretation of the filename.

     The `SELECT ... INTO OUTFILE' statement is intended primarily to
     let you very quickly dump a table to a text file on the server
     machine. If you want to create the resulting file on some client
     host other than the server host, you cannot use `SELECT ... INTO
     OUTFILE'. In that case, you should instead use a command such as
     `mysql -e "SELECT ..." > FILE_NAME' to generate the file on the
     client host.

     `SELECT ... INTO OUTFILE' is the complement of `LOAD DATA INFILE';
     the syntax for the EXPORT_OPTIONS part of the statement consists
     of the same `FIELDS' and `LINES' clauses that are used with the
     `LOAD DATA INFILE' statement. See *Note load-data::.

     Column values are dumped using the `binary' character set. In
     effect, there is no character set conversion. If a table contains
     columns in several character sets, the output data file will as
     well and you may not be able to reload the file correctly.

     `FIELDS ESCAPED BY' controls how to write special characters. If
     the `FIELDS ESCAPED BY' character is not empty, it is used as a
     prefix that precedes following characters on output:

        * The `FIELDS ESCAPED BY' character

        * The `FIELDS [OPTIONALLY] ENCLOSED BY' character

        * The first character of the `FIELDS TERMINATED BY' and `LINES
          TERMINATED BY' values

        * ASCII `NUL' (the zero-valued byte; what is actually written
          following the escape character is ASCII ``0'', not a
          zero-valued byte)

     The `FIELDS TERMINATED BY', `ENCLOSED BY', `ESCAPED BY', or `LINES
     TERMINATED BY' characters _must_ be escaped so that you can read
     the file back in reliably.  ASCII `NUL' is escaped to make it
     easier to view with some pagers.

     The resulting file does not have to conform to SQL syntax, so
     nothing else need be escaped.

     If the `FIELDS ESCAPED BY' character is empty, no characters are
     escaped and `NULL' is output as `NULL', not `\N'. It is probably
     not a good idea to specify an empty escape character, particularly
     if field values in your data contain any of the characters in the
     list just given.

     Here is an example that produces a file in the comma-separated
     values (CSV) format used by many programs:

          SELECT a,b,a+b INTO OUTFILE '/tmp/result.txt'
            FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"'
            LINES TERMINATED BY '\n'
            FROM test_table;

   * If you use `INTO DUMPFILE' instead of `INTO OUTFILE', MySQL writes
     only one row into the file, without any column or line termination
     and without performing any escape processing. This is useful if
     you want to store a `BLOB' value in a file.

   * The `INTO' clause can name a list of one or more variables, which
     can be user-defined variables, or parameters or local variables
     within a stored function or procedure body (see *Note
     select-into-statement::).  The selected values are assigned to the
     variables. The number of variables must match the number of
     columns.

   * *Note*:

     Any file created by `INTO OUTFILE' or `INTO DUMPFILE' is writable
     by all users on the server host. The reason for this is that the
     MySQL server cannot create a file that is owned by anyone other
     than the user under whose account it is running. (You should
     _never_ run `mysqld' as `root' for this and other reasons.) The
     file thus must be world-writable so that you can manipulate its
     contents.

   * The `SELECT' syntax description at the beginning this section
     shows the `INTO' clause near the end of the statement. It is also
     possible to use `INTO' immediately following the SELECT_EXPR list.

   * An `INTO' clause should not be used in a nested `SELECT' because
     such a `SELECT' must return its result to the outer context.

   * If you use `FOR UPDATE' with a storage engine that uses page or
     row locks, rows examined by the query are write-locked until the
     end of the current transaction. Using `LOCK IN SHARE MODE' sets a
     shared lock that allows other transactions to read the examined
     rows but not to update or delete them. See *Note
     innodb-locking-reads::.

Following the `SELECT' keyword, you can use a number of options that
affect the operation of the statement.

The `ALL', `DISTINCT', and `DISTINCTROW' options specify whether
duplicate rows should be returned. If none of these options are given,
the default is `ALL' (all matching rows are returned). `DISTINCT' and
`DISTINCTROW' are synonyms and specify removal of duplicate rows from
the result set.

`HIGH_PRIORITY', `STRAIGHT_JOIN', and options beginning with `SQL_' are
MySQL extensions to standard SQL.

   * `HIGH_PRIORITY' gives the `SELECT' higher priority than a statement
     that updates a table. You should use this only for queries that
     are very fast and must be done at once. A `SELECT HIGH_PRIORITY'
     query that is issued while the table is locked for reading runs
     even if there is an update statement waiting for the table to be
     free. This affects only storage engines that use only table-level
     locking (`MyISAM', `MEMORY', `MERGE').

     `HIGH_PRIORITY' cannot be used with `SELECT' statements that are
     part of a `UNION'.

   * `STRAIGHT_JOIN' forces the optimizer to join the tables in the
     order in which they are listed in the `FROM' clause. You can use
     this to speed up a query if the optimizer joins the tables in
     non-optimal order.  `STRAIGHT_JOIN' also can be used in the
     TABLE_REFERENCES list. See *Note join::.

     `STRAIGHT_JOIN' does not apply to any table that the optimizer
     treats as a `const' or `system' table. Such a table produces a
     single row, is read during the optimization phase of query
     execution, and references to its columns are replaced with the
     appropriate column values before query execution proceeds.  These
     tables will appear first in the query plan displayed by `EXPLAIN'.
     See *Note using-explain::. This exception may not apply to `const'
     or `system' tables that are used on the `NULL'-complemented side
     of an outer join (that is, the right-side table of a `LEFT JOIN'
     or the left-side table of a `RIGHT JOIN'.

   * `SQL_BIG_RESULT' can be used with `GROUP BY' or `DISTINCT' to tell
     the optimizer that the result set has many rows. In this case,
     MySQL directly uses disk-based temporary tables if needed, and
     prefers sorting to using a temporary table with a key on the
     `GROUP BY' elements.

   * `SQL_BUFFER_RESULT' forces the result to be put into a temporary
     table. This helps MySQL free the table locks early and helps in
     cases where it takes a long time to send the result set to the
     client.

   * `SQL_SMALL_RESULT' can be used with `GROUP BY' or `DISTINCT' to
     tell the optimizer that the result set is small. In this case,
     MySQL uses fast temporary tables to store the resulting table
     instead of using sorting. This should not normally be needed.

   * `SQL_CALC_FOUND_ROWS' tells MySQL to calculate how many rows there
     would be in the result set, disregarding any `LIMIT' clause. The
     number of rows can then be retrieved with `SELECT FOUND_ROWS()'.
     See *Note information-functions::.

   * The `SQL_CACHE' and `SQL_NO_CACHE' options affect caching of query
     results in the query cache (see *Note query-cache::). `SQL_CACHE'
     tells MySQL to store the result in the query cache if it is
     cacheable and the value of the `query_cache_type' system variable
     is `2' or `DEMAND'.  `SQL_NO_CACHE' tells MySQL not to store the
     result in the query cache. For a query that uses `UNION',
     subqueries, or views, the following rules apply:

        * `SQL_NO_CACHE' applies if it appears in any `SELECT' in the
          query.

        * For a cacheable query, `SQL_CACHE' applies if it appears in
          the first `SELECT' of the query, or in the first `SELECT' of
          a view referred to by the query.


File: manual.info,  Node: join,  Next: index-hints,  Prev: select,  Up: select

12.2.7.1 `JOIN' Syntax
......................

MySQL supports the following `JOIN' syntaxes for the TABLE_REFERENCES
part of `SELECT' statements and multiple-table `DELETE' and `UPDATE'
statements:

     TABLE_REFERENCES:
         TABLE_REFERENCE [, TABLE_REFERENCE] ...

     TABLE_REFERENCE:
         TABLE_FACTOR
       | JOIN_TABLE

     TABLE_FACTOR:
         TBL_NAME [[AS] ALIAS] [INDEX_HINT_LIST]
       | TABLE_SUBQUERY [AS] ALIAS
       | ( TABLE_REFERENCES )
       | { OJ TABLE_REFERENCE LEFT OUTER JOIN TABLE_REFERENCE
             ON CONDITIONAL_EXPR }

     JOIN_TABLE:
         TABLE_REFERENCE [INNER | CROSS] JOIN TABLE_FACTOR [JOIN_CONDITION]
       | TABLE_REFERENCE STRAIGHT_JOIN TABLE_FACTOR
       | TABLE_REFERENCE STRAIGHT_JOIN TABLE_FACTOR ON CONDITIONAL_EXPR
       | TABLE_REFERENCE {LEFT|RIGHT} [OUTER] JOIN TABLE_REFERENCE JOIN_CONDITION
       | TABLE_REFERENCE NATURAL [{LEFT|RIGHT} [OUTER]] JOIN TABLE_FACTOR

     JOIN_CONDITION:
         ON CONDITIONAL_EXPR
       | USING (COLUMN_LIST)

     INDEX_HINT_LIST:
         INDEX_HINT [, INDEX_HINT] ...

     INDEX_HINT:
         USE {INDEX|KEY}
           [{FOR {JOIN|ORDER BY|GROUP BY}] ([INDEX_LIST])
       | IGNORE {INDEX|KEY}
           [{FOR {JOIN|ORDER BY|GROUP BY}] (INDEX_LIST)
       | FORCE {INDEX|KEY}
           [{FOR {JOIN|ORDER BY|GROUP BY}] (INDEX_LIST)

     INDEX_LIST:
         INDEX_NAME [, INDEX_NAME] ...

A table reference is also known as a join expression.

The syntax of TABLE_FACTOR is extended in comparison with the SQL
Standard. The latter accepts only TABLE_REFERENCE, not a list of them
inside a pair of parentheses.

This is a conservative extension if we consider each comma in a list of
TABLE_REFERENCE items as equivalent to an inner join. For example:

     SELECT * FROM t1 LEFT JOIN (t2, t3, t4)
                      ON (t2.a=t1.a AND t3.b=t1.b AND t4.c=t1.c)

is equivalent to:

     SELECT * FROM t1 LEFT JOIN (t2 CROSS JOIN t3 CROSS JOIN t4)
                      ON (t2.a=t1.a AND t3.b=t1.b AND t4.c=t1.c)

In MySQL, `CROSS JOIN' is a syntactic equivalent to `INNER JOIN' (they
can replace each other). In standard SQL, they are not equivalent.
`INNER JOIN' is used with an `ON' clause, `CROSS JOIN' is used
otherwise.

In general, parentheses can be ignored in join expressions containing
only inner join operations. MySQL also supports nested joins (see *Note
nested-joins::).

Index hints can be specified to affect how the MySQL optimizer makes
use of indexes. For more information, see *Note index-hints::.

The following list describes general factors to take into account when
writing joins.

   * A table reference can be aliased using `TBL_NAME AS ALIAS_NAME' or
     TBL_NAME ALIAS_NAME:

          SELECT t1.name, t2.salary
            FROM employee AS t1 INNER JOIN info AS t2 ON t1.name = t2.name;

          SELECT t1.name, t2.salary
            FROM employee t1 INNER JOIN info t2 ON t1.name = t2.name;

   * A TABLE_SUBQUERY is also known as a subquery in the `FROM' clause.
     Such subqueries _must_ include an alias to give the subquery
     result a table name. A trivial example follows; see also *Note
     unnamed-views::.

          SELECT * FROM (SELECT 1, 2, 3) AS t1;

   * `INNER JOIN' and `,' (comma) are semantically equivalent in the
     absence of a join condition: both produce a Cartesian product
     between the specified tables (that is, each and every row in the
     first table is joined to each and every row in the second table).

     However, the precedence of the comma operator is less than of
     `INNER JOIN', `CROSS JOIN', `LEFT JOIN', and so on. If you mix
     comma joins with the other join types when there is a join
     condition, an error of the form `Unknown column 'COL_NAME' in 'on
     clause'' may occur. Information about dealing with this problem is
     given later in this section.

   * The CONDITIONAL_EXPR used with `ON' is any conditional expression
     of the form that can be used in a `WHERE' clause.  Generally, you
     should use the `ON' clause for conditions that specify how to join
     tables, and the `WHERE' clause to restrict which rows you want in
     the result set.

   * If there is no matching row for the right table in the `ON' or
     `USING' part in a `LEFT JOIN', a row with all columns set to
     `NULL' is used for the right table. You can use this fact to find
     rows in a table that have no counterpart in another table:

          SELECT left_tbl.*
            FROM left_tbl LEFT JOIN right_tbl ON left_tbl.id = right_tbl.id
            WHERE right_tbl.id IS NULL;

     This example finds all rows in `left_tbl' with an `id' value that
     is not present in `right_tbl' (that is, all rows in `left_tbl'
     with no corresponding row in `right_tbl'). This assumes that
     `right_tbl.id' is declared `NOT NULL'. See *Note
     left-join-optimization::.

   * The `USING(COLUMN_LIST)' clause names a list of columns that must
     exist in both tables. If tables `a' and `b' both contain columns
     `c1', `c2', and `c3', the following join compares corresponding
     columns from the two tables:

          a LEFT JOIN b USING (c1,c2,c3)

   * The `NATURAL [LEFT] JOIN' of two tables is defined to be
     semantically equivalent to an `INNER JOIN' or a `LEFT JOIN' with a
     `USING' clause that names all columns that exist in both tables.

   * `RIGHT JOIN' works analogously to `LEFT JOIN'. To keep code
     portable across databases, it is recommended that you use `LEFT
     JOIN' instead of `RIGHT JOIN'.

   * The `{ OJ ... LEFT OUTER JOIN ...}' syntax shown in the join
     syntax description exists only for compatibility with ODBC. The
     curly braces in the syntax should be written literally; they are
     not metasyntax as used elsewhere in syntax descriptions.

     As of MySQL 5.1.24, you can use other types of joins within `{ OJ
     ... }', such as `INNER JOIN' or `RIGHT OUTER JOIN'. This helps
     with compatibility with some third-party applications, but is not
     official ODBC syntax.

   * `STRAIGHT_JOIN' is similar to `JOIN', except that the left table is
     always read before the right table. This can be used for those
     (few) cases for which the join optimizer puts the tables in the
     wrong order.

Some join examples:

     SELECT * FROM table1, table2;

     SELECT * FROM table1 INNER JOIN table2 ON table1.id=table2.id;

     SELECT * FROM table1 LEFT JOIN table2 ON table1.id=table2.id;

     SELECT * FROM table1 LEFT JOIN table2 USING (id);

     SELECT * FROM table1 LEFT JOIN table2 ON table1.id=table2.id
       LEFT JOIN table3 ON table2.id=table3.id;

*Join Processing Changes in MySQL 5.0.12*

*Note*:

Natural joins and joins with `USING', including outer join variants,
are processed according to the SQL:2003 standard. The goal was to align
the syntax and semantics of MySQL with respect to `NATURAL JOIN' and
`JOIN ... USING' according to SQL:2003. However, these changes in join
processing can result in different output columns for some joins. Also,
some queries that appeared to work correctly in older versions (prior
to 5.0.12) must be rewritten to comply with the standard.

These changes have five main aspects:

   * The way that MySQL determines the result columns of `NATURAL' or
     `USING' join operations (and thus the result of the entire `FROM'
     clause).

   * Expansion of `SELECT *' and `SELECT TBL_NAME.*' into a list of
     selected columns.

   * Resolution of column names in `NATURAL' or `USING' joins.

   * Transformation of `NATURAL' or `USING' joins into `JOIN ...  ON'.

   * Resolution of column names in the `ON' condition of a `JOIN ...
     ON'.

The following list provides more detail about several effects of
current join processing versus join processing in older versions. The
term `previously' means `prior to MySQL 5.0.12.'

   * The columns of a `NATURAL' join or a `USING' join may be different
     from previously. Specifically, redundant output columns no longer
     appear, and the order of columns for `SELECT *' expansion may be
     different from before.

     Consider this set of statements:

          CREATE TABLE t1 (i INT, j INT);
          CREATE TABLE t2 (k INT, j INT);
          INSERT INTO t1 VALUES(1,1);
          INSERT INTO t2 VALUES(1,1);
          SELECT * FROM t1 NATURAL JOIN t2;
          SELECT * FROM t1 JOIN t2 USING (j);

     Previously, the statements produced this output:

          +------+------+------+------+
          | i    | j    | k    | j    |
          +------+------+------+------+
          |    1 |    1 |    1 |    1 |
          +------+------+------+------+
          +------+------+------+------+
          | i    | j    | k    | j    |
          +------+------+------+------+
          |    1 |    1 |    1 |    1 |
          +------+------+------+------+

     In the first `SELECT' statement, column `j' appears in both tables
     and thus becomes a join column, so, according to standard SQL, it
     should appear only once in the output, not twice. Similarly, in the
     second SELECT statement, column `j' is named in the `USING' clause
     and should appear only once in the output, not twice. But in both
     cases, the redundant column is not eliminated. Also, the order of
     the columns is not correct according to standard SQL.

     Now the statements produce this output:

          +------+------+------+
          | j    | i    | k    |
          +------+------+------+
          |    1 |    1 |    1 |
          +------+------+------+
          +------+------+------+
          | j    | i    | k    |
          +------+------+------+
          |    1 |    1 |    1 |
          +------+------+------+

     The redundant column is eliminated and the column order is correct
     according to standard SQL:

        * First, coalesced common columns of the two joined tables, in
          the order in which they occur in the first table

        * Second, columns unique to the first table, in order in which
          they occur in that table

        * Third, columns unique to the second table, in order in which
          they occur in that table

     The single result column that replaces two common columns is
     defined via the coalesce operation. That is, for two `t1.a' and
     `t2.a' the resulting single join column `a' is defined as `a =
     COALESCE(t1.a, t2.a)', where:

          COALESCE(x, y) = (CASE WHEN V1 IS NOT NULL THEN V1 ELSE V2 END)

     If the join operation is any other join, the result columns of the
     join consists of the concatenation of all columns of the joined
     tables. This is the same as previously.

     A consequence of the definition of coalesced columns is that, for
     outer joins, the coalesced column contains the value of the
     non-`NULL' column if one of the two columns is always `NULL'. If
     neither or both columns are `NULL', both common columns have the
     same value, so it doesn't matter which one is chosen as the value
     of the coalesced column. A simple way to interpret this is to
     consider that a coalesced column of an outer join is represented
     by the common column of the inner table of a `JOIN'. Suppose that
     the tables `t1(a,b)' and `t2(a,c)' have the following contents:

          t1    t2
          ----  ----
          1 x   2 z
          2 y   3 w

     Then:

          mysql> SELECT * FROM t1 NATURAL LEFT JOIN t2;
          +------+------+------+
          | a    | b    | c    |
          +------+------+------+
          |    1 | x    | NULL |
          |    2 | y    | z    |
          +------+------+------+

     Here column `a' contains the values of `t1.a'.

          mysql> SELECT * FROM t1 NATURAL RIGHT JOIN t2;
          +------+------+------+
          | a    | c    | b    |
          +------+------+------+
          |    2 | z    | y    |
          |    3 | w    | NULL |
          +------+------+------+

     Here column `a' contains the values of `t2.a'.

     Compare these results to the otherwise equivalent queries with
     `JOIN ... ON':

          mysql> SELECT * FROM t1 LEFT JOIN t2 ON (t1.a = t2.a);
          +------+------+------+------+
          | a    | b    | a    | c    |
          +------+------+------+------+
          |    1 | x    | NULL | NULL |
          |    2 | y    |    2 | z    |
          +------+------+------+------+

          mysql> SELECT * FROM t1 RIGHT JOIN t2 ON (t1.a = t2.a);
          +------+------+------+------+
          | a    | b    | a    | c    |
          +------+------+------+------+
          |    2 | y    |    2 | z    |
          | NULL | NULL |    3 | w    |
          +------+------+------+------+

   * Previously, a `USING' clause could be rewritten as an `ON' clause
     that compares corresponding columns. For example, the following two
     clauses were semantically identical:

          a LEFT JOIN b USING (c1,c2,c3)
          a LEFT JOIN b ON a.c1=b.c1 AND a.c2=b.c2 AND a.c3=b.c3

     Now the two clauses no longer are quite the same:

        * With respect to determining which rows satisfy the join
          condition, both joins remain semantically identical.

        * With respect to determining which columns to display for
          `SELECT *' expansion, the two joins are not semantically
          identical. The `USING' join selects the coalesced value of
          corresponding columns, whereas the `ON' join selects all
          columns from all tables. For the preceding `USING' join,
          `SELECT *' selects these values:

               COALESCE(a.c1,b.c1), COALESCE(a.c2,b.c2), COALESCE(a.c3,b.c3)

          For the `ON' join, `SELECT *' selects these values:

               a.c1, a.c2, a.c3, b.c1, b.c2, b.c3

          With an inner join, `COALESCE(a.c1,b.c1)' is the same as
          either `a.c1' or `b.c1' because both columns will have the
          same value. With an outer join (such as `LEFT JOIN'), one of
          the two columns can be `NULL'. That column will be omitted
          from the result.

   * The evaluation of multi-way natural joins differs in a very
     important way that affects the result of `NATURAL' or `USING' joins
     and that can require query rewriting. Suppose that you have three
     tables `t1(a,b)', `t2(c,b)', and `t3(a,c)' that each have one row:
     `t1(1,2)', `t2(10,2)', and `t3(7,10)'. Suppose also that you have
     this `NATURAL JOIN' on the three tables:

          SELECT ... FROM t1 NATURAL JOIN t2 NATURAL JOIN t3;

     Previously, the left operand of the second join was considered to
     be `t2', whereas it should be the nested join `(t1 NATURAL JOIN
     t2)'. As a result, the columns of `t3' are checked for common
     columns only in `t2', and, if `t3' has common columns with `t1',
     these columns are not used as equi-join columns. Thus, previously,
     the preceding query was transformed to the following equi-join:

          SELECT ... FROM t1, t2, t3
            WHERE t1.b = t2.b AND t2.c = t3.c;

     That join is missing one more equi-join predicate `(t1.a = t3.a)'.
     As a result, it produces one row, not the empty result that it
     should. The correct equivalent query is this:

          SELECT ... FROM t1, t2, t3
            WHERE t1.b = t2.b AND t2.c = t3.c AND t1.a = t3.a;

     If you require the same query result in current versions of MySQL
     as in older versions, rewrite the natural join as the first
     equi-join.

   * Previously, the comma operator (`,') and `JOIN' both had the same
     precedence, so the join expression `t1, t2 JOIN t3' was
     interpreted as `((t1, t2) JOIN t3)'. Now `JOIN' has higher
     precedence, so the expression is interpreted as `(t1, (t2 JOIN
     t3))'. This change affects statements that use an `ON' clause,
     because that clause can refer only to columns in the operands of
     the join, and the change in precedence changes interpretation of
     what those operands are.

     Example:

          CREATE TABLE t1 (i1 INT, j1 INT);
          CREATE TABLE t2 (i2 INT, j2 INT);
          CREATE TABLE t3 (i3 INT, j3 INT);
          INSERT INTO t1 VALUES(1,1);
          INSERT INTO t2 VALUES(1,1);
          INSERT INTO t3 VALUES(1,1);
          SELECT * FROM t1, t2 JOIN t3 ON (t1.i1 = t3.i3);

          SELECT left_tbl.*
            FROM { OJ left_tbl LEFT OUTER JOIN right_tbl ON left_tbl.id = right_tbl.id }
            WHERE right_tbl.id IS NULL;

     Previously, the `SELECT' was legal due to the implicit grouping of
     `t1,t2' as `(t1,t2)'. Now the `JOIN' takes precedence, so the
     operands for the `ON' clause are `t2' and `t3'. Because `t1.i1' is
     not a column in either of the operands, the result is an `Unknown
     column 't1.i1' in 'on clause'' error. To allow the join to be
     processed, group the first two tables explicitly with parentheses
     so that the operands for the `ON' clause are `(t1,t2)' and `t3':

          SELECT * FROM (t1, t2) JOIN t3 ON (t1.i1 = t3.i3);

     Alternatively, avoid the use of the comma operator and use `JOIN'
     instead:

          SELECT * FROM t1 JOIN t2 JOIN t3 ON (t1.i1 = t3.i3);

     This change also applies to statements that mix the comma operator
     with `INNER JOIN', `CROSS JOIN', `LEFT JOIN', and `RIGHT JOIN',
     all of which now have higher precedence than the comma operator.

   * Previously, the `ON' clause could refer to columns in tables named
     to its right. Now an `ON' clause can refer only to its operands.

     Example:

          CREATE TABLE t1 (i1 INT);
          CREATE TABLE t2 (i2 INT);
          CREATE TABLE t3 (i3 INT);
          SELECT * FROM t1 JOIN t2 ON (i1 = i3) JOIN t3;

     Previously, the `SELECT' statement was legal. Now the statement
     fails with an `Unknown column 'i3' in 'on clause'' error because
     `i3' is a column in `t3', which is not an operand of the `ON'
     clause.  The statement should be rewritten as follows:

          SELECT * FROM t1 JOIN t2 JOIN t3 ON (i1 = i3);

   * Resolution of column names in `NATURAL' or `USING' joins is
     different than previously.  For column names that are outside the
     `FROM' clause, MySQL now handles a superset of the queries
     compared to previously. That is, in cases when MySQL formerly
     issued an error that some column is ambiguous, the query now is
     handled correctly. This is due to the fact that MySQL now treats
     the common columns of `NATURAL' or `USING' joins as a single
     column, so when a query refers to such columns, the query compiler
     does not consider them as ambiguous.

     Example:

          SELECT * FROM t1 NATURAL JOIN t2 WHERE b > 1;

     Previously, this query would produce an error `ERROR 1052 (23000):
     Column 'b' in where clause is ambiguous'. Now the query produces
     the correct result:

          +------+------+------+
          | b    | c    | y    |
          +------+------+------+
          |    4 |    2 |    3 |
          +------+------+------+

     One extension of MySQL compared to the SQL:2003 standard is that
     MySQL allows you to qualify the common (coalesced) columns of
     `NATURAL' or `USING' joins (just as previously), while the
     standard disallows that.


File: manual.info,  Node: index-hints,  Next: union,  Prev: join,  Up: select

12.2.7.2 Index Hint Syntax
..........................

You can provide hints to give the optimizer information about how to
choose indexes during query processing.  *Note join::, describes the
general syntax for specifying tables in a `SELECT' statement. The
syntax for an individual table, including that for index hints, looks
like this:

     TBL_NAME [[AS] ALIAS] [INDEX_HINT_LIST]

     INDEX_HINT_LIST:
         INDEX_HINT [, INDEX_HINT] ...

     INDEX_HINT:
         USE {INDEX|KEY}
           [{FOR {JOIN|ORDER BY|GROUP BY}] ([INDEX_LIST])
       | IGNORE {INDEX|KEY}
           [{FOR {JOIN|ORDER BY|GROUP BY}] (INDEX_LIST)
       | FORCE {INDEX|KEY}
           [{FOR {JOIN|ORDER BY|GROUP BY}] (INDEX_LIST)

     INDEX_LIST:
         INDEX_NAME [, INDEX_NAME] ...

By specifying `USE INDEX (INDEX_LIST)', you can tell MySQL to use only
one of the named indexes to find rows in the table. The alternative
syntax `IGNORE INDEX (INDEX_LIST)' can be used to tell MySQL to not use
some particular index or indexes. These hints are useful if `EXPLAIN'
shows that MySQL is using the wrong index from the list of possible
indexes.

You can also use `FORCE INDEX', which acts like `USE INDEX
(INDEX_LIST)' but with the addition that a table scan is assumed to be
_very_ expensive. In other words, a table scan is used only if there is
no way to use one of the given indexes to find rows in the table.

Each hint requires the names of _indexes_, not the names of columns.
The name of a `PRIMARY KEY' is `PRIMARY'. To see the index names for a
table, use `SHOW INDEX'.

An INDEX_NAME value need not be a full index name. It can be an
unambiguous prefix of an index name. If a prefix is given that is
ambiguous, an error occurs.

Index hints do not work for `FULLTEXT' indexes.

Prior to MySQL 5.1.17, `USE INDEX', `IGNORE INDEX', and `FORCE INDEX'
affect only which indexes are used when MySQL decides how to find rows
in the table and how to process joins.  They do not affect whether an
index is used when resolving an `ORDER BY' or `GROUP BY' clause.

Examples:

     SELECT * FROM table1 USE INDEX (col1_index,col2_index)
       WHERE col1=1 AND col2=2 AND col3=3;

     SELECT * FROM table1 IGNORE INDEX (col3_index)
       WHERE col1=1 AND col2=2 AND col3=3;

As of MySQL 5.1.17, the syntax for index hints is extended in the
following ways:

   * It is syntactically valid to specify an empty INDEX_LIST for `USE
     INDEX', which means `use no indexes.' Specifying an empty
     INDEX_LIST for `FORCE INDEX' or `IGNORE INDEX' is a syntax error.

   * You can specify the scope of a index hint by adding a `FOR' clause
     to the hint. This provides more fine-grained control over the
     optimizer's selection of an execution plan for various phases of
     query processing. To affect only the indexes used when MySQL
     decides how to find rows in the table and how to process joins,
     use `FOR JOIN'. To influence index usage for sorting or grouping
     rows, use `FOR ORDER BY' or `FOR GROUP BY'. (However, if there is a
     covering index for the table and it is used to access the table,
     the optimizer will ignore `IGNORE INDEX FOR {ORDER BY|GROUP BY}'
     hints that disable that index.)

   * You can specify multiple index hints:

          SELECT * FROM t1 USE INDEX (i1) IGNORE INDEX FOR ORDER BY (i2) ORDER BY a;

     It is not a error to name the same index in several hints (even
     within the same hint):

          SELECT * FROM t1 USE INDEX (i1) USE INDEX (i1,i1);

     However, it is an error to mix `USE INDEX' and `FORCE INDEX' for
     the same table:

          SELECT * FROM t1 USE INDEX FOR JOIN (i1) FORCE INDEX FOR JOIN (i2);

The default scope of index hints also is changed as of MySQL 5.1.17.
Formerly, index hints applied only to how indexes are used for
retrieval of records and not during resolution of `ORDER BY' or `GROUP
BY' clauses. As of 5.1.17, if you specify no `FOR' clause for an index
hint, the hint by default applies to all parts of the statement. For
example, this hint:

     IGNORE INDEX (i1)

is equivalent to this combination of hints:

     IGNORE INDEX FOR JOIN (i1)
     IGNORE INDEX FOR ORDER BY (i1)
     IGNORE INDEX FOR GROUP BY (i1)

To cause the server to use the older behavior for hint scope when no
`FOR' clause is present (so that hints apply only to row retrieval),
enable the `old' system variable at server startup. Take care about
enabling this variable in a replication setup. With statement-based
binary logging, having different modes for the master and slaves might
lead to replication errors.

When index hints are processed, they are collected in a single list by
type (`USE', `FORCE', `IGNORE') and by scope (`FOR JOIN', `FOR ORDER
BY', `FOR GROUP BY'). For example:

     SELECT * FROM t1
       USE INDEX () IGNORE INDEX (i2) USE INDEX (i1) USE INDEX (i2);

is equivalent to:

     SELECT * FROM t1
        USE INDEX (i1,i2) IGNORE INDEX (i2);

The index hints then are applied for each scope in the following order:

  1. `{USE|FORCE} INDEX' is applied if present.  (If not, the
     optimizer-determined set of indexes is used.)

  2. `IGNORE INDEX' is applied over the result of the previous step.
     For example:

          SELECT * FROM t1 USE INDEX (i1) IGNORE INDEX (i2) USE INDEX (i2)

     is equivalent to:

          SELECT * FROM t1 USE INDEX (i1).


File: manual.info,  Node: union,  Prev: index-hints,  Up: select

12.2.7.3 `UNION' Syntax
.......................

     SELECT ...
     UNION [ALL | DISTINCT] SELECT ...
     [UNION [ALL | DISTINCT] SELECT ...]

`UNION' is used to combine the result from multiple `SELECT' statements
into a single result set.

The column names from the first `SELECT' statement are used as the
column names for the results returned.  Selected columns listed in
corresponding positions of each `SELECT' statement should have the same
data type. (For example, the first column selected by the first
statement should have the same type as the first column selected by the
other statements.)

If the data types of corresponding `SELECT' columns do not match, the
types and lengths of the columns in the `UNION' result take into
account the values retrieved by all of the `SELECT' statements.  For
example, consider the following:

     mysql> SELECT REPEAT('a',1) UNION SELECT REPEAT('b',10);
     +---------------+
     | REPEAT('a',1) |
     +---------------+
     | a             |
     | bbbbbbbbbb    |
     +---------------+

(In some earlier versions of MySQL, only the type and length from the
first `SELECT' would have been used and the second row would have been
truncated to a length of 1.)

The `SELECT' statements are normal select statements, but with the
following restrictions:

   * Only the last `SELECT' statement can use `INTO OUTFILE'. (However,
     the entire `UNION' result is written to the file.)

   * `HIGH_PRIORITY' cannot be used with `SELECT' statements that are
     part of a `UNION'. If you specify it for the first `SELECT', it
     has no effect. If you specify it for any subsequent `SELECT'
     statements, a syntax error results.

The default behavior for `UNION' is that duplicate rows are removed
from the result. The optional `DISTINCT' keyword has no effect other
than the default because it also specifies duplicate-row removal. With
the optional `ALL' keyword, duplicate-row removal does not occur and
the result includes all matching rows from all the `SELECT' statements.

You can mix `UNION ALL' and `UNION DISTINCT' in the same query. Mixed
`UNION' types are treated such that a `DISTINCT' union overrides any
`ALL' union to its left. A `DISTINCT' union can be produced explicitly
by using `UNION DISTINCT' or implicitly by using `UNION' with no
following `DISTINCT' or `ALL' keyword.

To use an `ORDER BY' or `LIMIT' clause to sort or limit the entire
`UNION' result, parenthesize the individual `SELECT' statements and
place the `ORDER BY' or `LIMIT' after the last one. The following
example uses both clauses:

     (SELECT a FROM t1 WHERE a=10 AND B=1)
     UNION
     (SELECT a FROM t2 WHERE a=11 AND B=2)
     ORDER BY a LIMIT 10;

This kind of `ORDER BY' cannot use column references that include a
table name (that is, names in TBL_NAME.COL_NAME format). Instead,
provide a column alias in the first `SELECT' statement and refer to the
alias in the `ORDER BY'. (Alternatively, refer to the column in the
`ORDER BY' using its column position. However, use of column positions
is deprecated.)

Also, if a column to be sorted is aliased, the `ORDER BY' clause _must_
refer to the alias, not the column name. The first of the following
statements will work, but the second will fail with an `Unknown column
'a' in 'order clause'' error:

     (SELECT a AS b FROM t) UNION (SELECT ...) ORDER BY b;
     (SELECT a AS b FROM t) UNION (SELECT ...) ORDER BY a;

To apply `ORDER BY' or `LIMIT' to an individual `SELECT', place the
clause inside the parentheses that enclose the `SELECT':

     (SELECT a FROM t1 WHERE a=10 AND B=1 ORDER BY a LIMIT 10)
     UNION
     (SELECT a FROM t2 WHERE a=11 AND B=2 ORDER BY a LIMIT 10);

However, use of `ORDER BY' for individual `SELECT' statements implies
nothing about the order in which the rows appear in the final result
because `UNION' by default produces an unordered set of rows.
Therefore, the use of `ORDER BY' in this context is typically in
conjunction with `LIMIT', so that it is used to determine the subset of
the selected rows to retrieve for the `SELECT', even though it does not
necessarily affect the order of those rows in the final `UNION' result.
If `ORDER BY' appears without `LIMIT' in a `SELECT', it is optimized
away because it will have no effect anyway.

To cause rows in a `UNION' result to consist of the sets of rows
retrieved by each `SELECT' one after the other, select an additional
column in each `SELECT' to use as a sort column and add an `ORDER BY'
following the last `SELECT':

     (SELECT 1 AS sort_col, col1a, col1b, ... FROM t1)
     UNION
     (SELECT 2, col2a, col2b, ... FROM t2) ORDER BY sort_col;

To additionally maintain sort order within individual `SELECT' results,
add a secondary column to the `ORDER BY' clause:

     (SELECT 1 AS sort_col, col1a, col1b, ... FROM t1)
     UNION
     (SELECT 2, col2a, col2b, ... FROM t2) ORDER BY sort_col, col1a;

Use of an additional column also enables you to determine which
`SELECT' each row comes from. Extra columns can provide other
identifying information as well, such as a string that indicates a
table name.


File: manual.info,  Node: subqueries,  Next: truncate,  Prev: select,  Up: sql-syntax-data-manipulation

12.2.8 Subquery Syntax
----------------------

* Menu:

* scalar-subqueries::            The Subquery as Scalar Operand
* comparisons-using-subqueries::  Comparisons Using Subqueries
* any-in-some-subqueries::       Subqueries with `ANY', `IN', and `SOME'
* all-subqueries::               Subqueries with `ALL'
* row-subqueries::               Row Subqueries
* exists-and-not-exists-subqueries::  `EXISTS' and `NOT EXISTS'
* correlated-subqueries::        Correlated Subqueries
* unnamed-views::                Subqueries in the `FROM' clause
* subquery-errors::              Subquery Errors
* optimizing-subqueries::        Optimizing Subqueries
* rewriting-subqueries::         Rewriting Subqueries as Joins

A subquery is a `SELECT' statement within another statement.

Starting with MySQL 4.1, all subquery forms and operations that the SQL
standard requires are supported, as well as a few features that are
MySQL-specific.

Here is an example of a subquery:

     SELECT * FROM t1 WHERE column1 = (SELECT column1 FROM t2);

In this example, `SELECT * FROM t1 ...' is the _outer query_ (or _outer
statement_), and `(SELECT column1 FROM t2)' is the _subquery_. We say
that the subquery is _nested_ within the outer query, and in fact it is
possible to nest subqueries within other subqueries, to a considerable
depth. A subquery must always appear within parentheses.

The main advantages of subqueries are:

   * They allow queries that are _structured_ so that it is possible to
     isolate each part of a statement.

   * They provide alternative ways to perform operations that would
     otherwise require complex joins and unions.

   * They are, in many people's opinion, more readable than complex
     joins or unions. Indeed, it was the innovation of subqueries that
     gave people the original idea of calling the early SQL `Structured
     Query Language.'

Here is an example statement that shows the major points about subquery
syntax as specified by the SQL standard and supported in MySQL:

     DELETE FROM t1
     WHERE s11 > ANY
      (SELECT COUNT(*) /* no hint */ FROM t2
       WHERE NOT EXISTS
        (SELECT * FROM t3
         WHERE ROW(5*t2.s1,77)=
          (SELECT 50,11*s1 FROM t4 UNION SELECT 50,77 FROM
           (SELECT * FROM t5) AS t5)));

A subquery can return a scalar (a single value), a single row, a single
column, or a table (one or more rows of one or more columns). These are
called scalar, column, row, and table subqueries. Subqueries that
return a particular kind of result often can be used only in certain
contexts, as described in the following sections.

There are few restrictions on the type of statements in which
subqueries can be used. A subquery can contain any of the keywords or
clauses that an ordinary `SELECT' can contain: `DISTINCT', `GROUP BY',
`ORDER BY', `LIMIT', joins, index hints, `UNION' constructs, comments,
functions, and so on.

One restriction is that a subquery's outer statement must be one of:
`SELECT', `INSERT', `UPDATE', `DELETE', `SET', or `DO'. Another
restriction is that currently you cannot modify a table and select from
the same table in a subquery. This applies to statements such as
`DELETE', `INSERT', `REPLACE', `UPDATE', and (because subqueries can be
used in the `SET' clause) `LOAD DATA INFILE'.

A more comprehensive discussion of restrictions on subquery use,
including performance issues for certain forms of subquery syntax, is
given in *Note subquery-restrictions::.


File: manual.info,  Node: scalar-subqueries,  Next: comparisons-using-subqueries,  Prev: subqueries,  Up: subqueries

12.2.8.1 The Subquery as Scalar Operand
.......................................

In its simplest form, a subquery is a scalar subquery that returns a
single value. A scalar subquery is a simple operand, and you can use it
almost anywhere a single column value or literal is legal, and you can
expect it to have those characteristics that all operands have: a data
type, a length, an indication whether it can be `NULL', and so on. For
example:

     CREATE TABLE t1 (s1 INT, s2 CHAR(5) NOT NULL);
     INSERT INTO t1 VALUES(100, 'abcde');
     SELECT (SELECT s2 FROM t1);

The subquery in this `SELECT' returns a single value (`'abcde'') that
has a data type of `CHAR', a length of 5, a character set and collation
equal to the defaults in effect at `CREATE TABLE' time, and an
indication that the value in the column can be `NULL'. In fact, almost
all subqueries can be `NULL'. If the table used in the example were
empty, the value of the subquery would be `NULL'.

There are a few contexts in which a scalar subquery cannot be used. If
a statement allows only a literal value, you cannot use a subquery. For
example, `LIMIT' requires literal integer arguments, and `LOAD DATA
INFILE' requires a literal string filename. You cannot use subqueries
to supply these values.

When you see examples in the following sections that contain the rather
spartan construct `(SELECT column1 FROM t1)', imagine that your own
code contains much more diverse and complex constructions.

Suppose that we make two tables:

     CREATE TABLE t1 (s1 INT);
     INSERT INTO t1 VALUES (1);
     CREATE TABLE t2 (s1 INT);
     INSERT INTO t2 VALUES (2);

Then perform a `SELECT':

     SELECT (SELECT s1 FROM t2) FROM t1;

The result is `2' because there is a row in `t2' containing a column
`s1' that has a value of `2'.

A scalar subquery can be part of an expression, but remember the
parentheses, even if the subquery is an operand that provides an
argument for a function. For example:

     SELECT UPPER((SELECT s1 FROM t1)) FROM t2;


File: manual.info,  Node: comparisons-using-subqueries,  Next: any-in-some-subqueries,  Prev: scalar-subqueries,  Up: subqueries

12.2.8.2 Comparisons Using Subqueries
.....................................

The most common use of a subquery is in the form:

     NON_SUBQUERY_OPERAND COMPARISON_OPERATOR (SUBQUERY)

Where COMPARISON_OPERATOR is one of these operators:

     =  >  <  >=  <=  <>

For example:

     ... 'a' = (SELECT column1 FROM t1)

At one time the only legal place for a subquery was on the right side
of a comparison, and you might still find some old DBMSs that insist on
this.

Here is an example of a common-form subquery comparison that you cannot
do with a join. It finds all the values in table `t1' that are equal to
a maximum value in table `t2':

     SELECT column1 FROM t1
     WHERE column1 = (SELECT MAX(column2) FROM t2);

Here is another example, which again is impossible with a join because
it involves aggregating for one of the tables. It finds all rows in
table `t1' containing a value that occurs twice in a given column:

     SELECT * FROM t1 AS t
     WHERE 2 = (SELECT COUNT(*) FROM t1 WHERE t1.id = t.id);

For a comparison performed with one of these operators, the subquery
must return a scalar, with the exception that `=' can be used with row
subqueries. See *Note row-subqueries::.


File: manual.info,  Node: any-in-some-subqueries,  Next: all-subqueries,  Prev: comparisons-using-subqueries,  Up: subqueries

12.2.8.3 Subqueries with `ANY', `IN', and `SOME'
................................................

Syntax:

     OPERAND COMPARISON_OPERATOR ANY (SUBQUERY)
     OPERAND IN (SUBQUERY)
     OPERAND COMPARISON_OPERATOR SOME (SUBQUERY)

The `ANY' keyword, which must follow a comparison operator, means
`return `TRUE' if the comparison is `TRUE' for `ANY' of the values in
the column that the subquery returns.' For example:

     SELECT s1 FROM t1 WHERE s1 > ANY (SELECT s1 FROM t2);

Suppose that there is a row in table `t1' containing `(10)'. The
expression is `TRUE' if table `t2' contains `(21,14,7)' because there
is a value `7' in `t2' that is less than `10'. The expression is
`FALSE' if table `t2' contains `(20,10)', or if table `t2' is empty.
The expression is _unknown_ if table `t2' contains `(NULL,NULL,NULL)'.

When used with a subquery, the word `IN' is an alias for `= ANY'. Thus,
these two statements are the same:

     SELECT s1 FROM t1 WHERE s1 = ANY (SELECT s1 FROM t2);
     SELECT s1 FROM t1 WHERE s1 IN    (SELECT s1 FROM t2);

`IN' and `= ANY' are not synonyms when used with an expression list.
`IN' can take an expression list, but `= ANY' cannot. See *Note
comparison-operators::.

`NOT IN' is not an alias for `<> ANY', but for `<> ALL'. See *Note
all-subqueries::.

The word `SOME' is an alias for `ANY'. Thus, these two statements are
the same:

     SELECT s1 FROM t1 WHERE s1 <> ANY  (SELECT s1 FROM t2);
     SELECT s1 FROM t1 WHERE s1 <> SOME (SELECT s1 FROM t2);

Use of the word `SOME' is rare, but this example shows why it might be
useful. To most people's ears, the English phrase `a is not equal to
any b' means `there is no b which is equal to a,' but that is not what
is meant by the SQL syntax. The syntax means `there is some b to which
a is not equal.' Using `<> SOME' instead helps ensure that everyone
understands the true meaning of the query.


File: manual.info,  Node: all-subqueries,  Next: row-subqueries,  Prev: any-in-some-subqueries,  Up: subqueries

12.2.8.4 Subqueries with `ALL'
..............................

Syntax:

     OPERAND COMPARISON_OPERATOR ALL (SUBQUERY)

The word `ALL', which must follow a comparison operator, means `return
`TRUE' if the comparison is `TRUE' for `ALL' of the values in the
column that the subquery returns.' For example:

     SELECT s1 FROM t1 WHERE s1 > ALL (SELECT s1 FROM t2);

Suppose that there is a row in table `t1' containing `(10)'. The
expression is `TRUE' if table `t2' contains `(-5,0,+5)' because `10' is
greater than all three values in `t2'. The expression is `FALSE' if
table `t2' contains `(12,6,NULL,-100)' because there is a single value
`12' in table `t2' that is greater than `10'. The expression is
_unknown_ (that is, `NULL') if table `t2' contains `(0,NULL,1)'.

Finally, if table `t2' is empty, the result is `TRUE'. So, the
following statement is `TRUE' when table `t2' is empty:

     SELECT * FROM t1 WHERE 1 > ALL (SELECT s1 FROM t2);

But this statement is `NULL' when table `t2' is empty:

     SELECT * FROM t1 WHERE 1 > (SELECT s1 FROM t2);

In addition, the following statement is `NULL' when table `t2' is empty:

     SELECT * FROM t1 WHERE 1 > ALL (SELECT MAX(s1) FROM t2);

In general, _tables containing `NULL' values_ and _empty tables_ are
`edge cases.' When writing subquery code, always consider whether you
have taken those two possibilities into account.

`NOT IN' is an alias for `<> ALL'. Thus, these two statements are the
same:

     SELECT s1 FROM t1 WHERE s1 <> ALL (SELECT s1 FROM t2);
     SELECT s1 FROM t1 WHERE s1 NOT IN (SELECT s1 FROM t2);


File: manual.info,  Node: row-subqueries,  Next: exists-and-not-exists-subqueries,  Prev: all-subqueries,  Up: subqueries

12.2.8.5 Row Subqueries
.......................

The discussion to this point has been of scalar or column subqueries;
that is, subqueries that return a single value or a column of values. A
_row subquery_ is a subquery variant that returns a single row and can
thus return more than one column value. Here are two examples:

     SELECT * FROM t1 WHERE (1,2) = (SELECT column1, column2 FROM t2);
     SELECT * FROM t1 WHERE ROW(1,2) = (SELECT column1, column2 FROM t2);

The queries here are both `TRUE' if table `t2' has a row where `column1
= 1' and `column2 = 2'.

The expressions `(1,2)' and `ROW(1,2)' are sometimes called _row
constructors_. The two are equivalent. They are legal in other contexts
as well. For example, the following two statements are semantically
equivalent (although the first one cannot be optimized until MySQL
5.1.12):

     SELECT * FROM t1 WHERE (column1,column2) = (1,1);
     SELECT * FROM t1 WHERE column1 = 1 AND column2 = 1;

The normal use of row constructors is for comparisons with subqueries
that return two or more columns. For example, the following query
answers the request, `find all rows in table `t1' that also exist in
table `t2'':

     SELECT column1,column2,column3
            FROM t1
            WHERE (column1,column2,column3) IN
                  (SELECT column1,column2,column3 FROM t2);


File: manual.info,  Node: exists-and-not-exists-subqueries,  Next: correlated-subqueries,  Prev: row-subqueries,  Up: subqueries

12.2.8.6 `EXISTS' and `NOT EXISTS'
..................................

If a subquery returns any rows at all, `EXISTS SUBQUERY' is `TRUE', and
`NOT EXISTS SUBQUERY' is `FALSE'. For example:

     SELECT column1 FROM t1 WHERE EXISTS (SELECT * FROM t2);

Traditionally, an `EXISTS' subquery starts with `SELECT *', but it
could begin with `SELECT 5' or `SELECT column1' or anything at all.
MySQL ignores the `SELECT' list in such a subquery, so it makes no
difference.

For the preceding example, if `t2' contains any rows, even rows with
nothing but `NULL' values, the `EXISTS' condition is `TRUE'. This is
actually an unlikely example because a `[NOT] EXISTS' subquery almost
always contains correlations. Here are some more realistic examples:

   * What kind of store is present in one or more cities?

          SELECT DISTINCT store_type FROM stores
            WHERE EXISTS (SELECT * FROM cities_stores
                          WHERE cities_stores.store_type = stores.store_type);

   * What kind of store is present in no cities?

          SELECT DISTINCT store_type FROM stores
            WHERE NOT EXISTS (SELECT * FROM cities_stores
                              WHERE cities_stores.store_type = stores.store_type);

   * What kind of store is present in all cities?

          SELECT DISTINCT store_type FROM stores s1
            WHERE NOT EXISTS (
              SELECT * FROM cities WHERE NOT EXISTS (
                SELECT * FROM cities_stores
                 WHERE cities_stores.city = cities.city
                 AND cities_stores.store_type = stores.store_type));

The last example is a double-nested `NOT EXISTS' query. That is, it has
a `NOT EXISTS' clause within a `NOT EXISTS' clause. Formally, it
answers the question `does a city exist with a store that is not in
`Stores''? But it is easier to say that a nested `NOT EXISTS' answers
the question `is X `TRUE' for all Y?'


File: manual.info,  Node: correlated-subqueries,  Next: unnamed-views,  Prev: exists-and-not-exists-subqueries,  Up: subqueries

12.2.8.7 Correlated Subqueries
..............................

A _correlated subquery_ is a subquery that contains a reference to a
table that also appears in the outer query. For example:

     SELECT * FROM t1 WHERE column1 = ANY
            (SELECT column1 FROM t2 WHERE t2.column2 = t1.column2);

Notice that the subquery contains a reference to a column of `t1', even
though the subquery's `FROM' clause does not mention a table `t1'. So,
MySQL looks outside the subquery, and finds `t1' in the outer query.

Suppose that table `t1' contains a row where `column1 = 5' and `column2
= 6'; meanwhile, table `t2' contains a row where `column1 = 5' and
`column2 = 7'. The simple expression `... WHERE column1 = ANY (SELECT
column1 FROM t2)' would be `TRUE', but in this example, the `WHERE'
clause within the subquery is `FALSE' (because `(5,6)' is not equal to
`(5,7)'), so the subquery as a whole is `FALSE'.

*Scoping rule:* MySQL evaluates from inside to outside. For example:

     SELECT column1 FROM t1 AS x
       WHERE x.column1 = (SELECT column1 FROM t2 AS x
         WHERE x.column1 = (SELECT column1 FROM t3
           WHERE x.column2 = t3.column1));

In this statement, `x.column2' must be a column in table `t2' because
`SELECT column1 FROM t2 AS x ...' renames `t2'. It is not a column in
table `t1' because `SELECT column1 FROM t1 ...' is an outer query that
is _farther out_.

For subqueries in `HAVING' or `ORDER BY' clauses, MySQL also looks for
column names in the outer select list.

For certain cases, a correlated subquery is optimized. For example:

     VAL IN (SELECT KEY_VAL FROM TBL_NAME WHERE CORRELATED_CONDITION)

Otherwise, they are inefficient and likely to be slow. Rewriting the
query as a join might improve performance.

Aggregate functions in correlated subqueries may contain outer
references, provided the function contains nothing but outer
references, and provided the function is not contained in another
function or expression.


File: manual.info,  Node: unnamed-views,  Next: subquery-errors,  Prev: correlated-subqueries,  Up: subqueries

12.2.8.8 Subqueries in the `FROM' clause
........................................

Subqueries are legal in a `SELECT' statement's `FROM' clause. The
actual syntax is:

     SELECT ... FROM (SUBQUERY) [AS] NAME ...

The `[AS] NAME' clause is mandatory, because every table in a `FROM'
clause must have a name. Any columns in the SUBQUERY select list must
have unique names.

For the sake of illustration, assume that you have this table:

     CREATE TABLE t1 (s1 INT, s2 CHAR(5), s3 FLOAT);

Here is how to use a subquery in the `FROM' clause, using the example
table:

     INSERT INTO t1 VALUES (1,'1',1.0);
     INSERT INTO t1 VALUES (2,'2',2.0);
     SELECT sb1,sb2,sb3
            FROM (SELECT s1 AS sb1, s2 AS sb2, s3*2 AS sb3 FROM t1) AS sb
            WHERE sb1 > 1;

Result: `2, '2', 4.0'.

Here is another example: Suppose that you want to know the average of a
set of sums for a grouped table. This does not work:

     SELECT AVG(SUM(column1)) FROM t1 GROUP BY column1;

However, this query provides the desired information:

     SELECT AVG(sum_column1)
            FROM (SELECT SUM(column1) AS sum_column1
                  FROM t1 GROUP BY column1) AS t1;

Notice that the column name used within the subquery (`sum_column1') is
recognized in the outer query.

Subqueries in the `FROM' clause can return a scalar, column, row, or
table. Subqueries in the `FROM' clause cannot be correlated subqueries,
unless used within the `ON' clause of a `JOIN' operation.

Subqueries in the `FROM' clause are executed even for the `EXPLAIN'
statement (that is, derived temporary tables are built). This occurs
because upper-level queries need information about all tables during the
optimization phase, and the table represented by a subquery in the
`FROM' clause is unavailable unless the subquery is executed.

It is possible under certain circumstances to modify table data using
`EXPLAIN SELECT'. This can occur if the outer query accesses any tables
and an inner query invokes a stored function that changes one or more
rows of a table. For example, suppose there are two tables `t1' and
`t2' in database `d1', created as shown here:

     mysql> CREATE DATABASE d1;
     Query OK, 1 row affected (0.00 sec)

     mysql> USE d1;
     Database changed

     mysql> CREATE TABLE t1 (c1 INT);
     Query OK, 0 rows affected (0.15 sec)

     mysql> CREATE TABLE t2 (c1 INT);
     Query OK, 0 rows affected (0.08 sec)

Now we create a stored function `f1' which modifies `t2':

     mysql> DELIMITER //
     mysql> CREATE FUNCTION f1(p1 INT) RETURNS INT
     mysql>   BEGIN
     mysql>     INSERT INTO t2 VALUES (p1);
     mysql>     RETURN p1;
     mysql>   END //
     Query OK, 0 rows affected (0.01 sec)

     mysql> DELIMITER ;

Referencing the function directly in an EXPLAIN SELECT does not have
any affect on t2, as shown here:

     mysql> SELECT * FROM t2;
     Empty set (0.00 sec)

     mysql> EXPLAIN SELECT f1(5);
     +----+-------------+-------+------+---------------+------+---------+------+------+----------------+
     | id | select_type | table | type | possible_keys | key  | key_len | ref  | rows | Extra          |
     +----+-------------+-------+------+---------------+------+---------+------+------+----------------+
     |  1 | SIMPLE      | NULL  | NULL | NULL          | NULL | NULL    | NULL | NULL | No tables used |
     +----+-------------+-------+------+---------------+------+---------+------+------+----------------+
     1 row in set (0.00 sec)

     mysql> SELECT * FROM t2;
     Empty set (0.00 sec)

This is because the `SELECT' statement did not reference any tables, as
can be seen in the `table' and `Extra' columns of the output. This is
also true of the following nested `SELECT':

     mysql> EXPLAIN SELECT NOW() AS a1, (SELECT f1(5)) AS a2;
     +----+-------------+-------+------+---------------+------+---------+------+------+----------------+
     | id | select_type | table | type | possible_keys | key  | key_len | ref  | rows | Extra          |
     +----+-------------+-------+------+---------------+------+---------+------+------+----------------+
     |  1 | PRIMARY     | NULL  | NULL | NULL          | NULL | NULL    | NULL | NULL | No tables used |
     +----+-------------+-------+------+---------------+------+---------+------+------+----------------+
     1 row in set, 1 warning (0.00 sec)

     mysql> SHOW WARNINGS;
     +-------+------+------------------------------------------+
     | Level | Code | Message                                  |
     +-------+------+------------------------------------------+
     | Note  | 1249 | Select 2 was reduced during optimization |
     +-------+------+------------------------------------------+
     1 row in set (0.00 sec)

     mysql> SELECT * FROM t2;
     Empty set (0.00 sec)

However, if the outer SELECT references any tables, then the optimizer
executes the statement in the subquery as well:

     mysql> EXPLAIN SELECT * FROM t1 AS a1, (SELECT f1(5)) AS a2;
     +----+-------------+------------+--------+---------------+------+---------+------+------+---------------------+
     | id | select_type | table      | type   | possible_keys | key  | key_len | ref  | rows | Extra               |
     +----+-------------+------------+--------+---------------+------+---------+------+------+---------------------+
     |  1 | PRIMARY     | a1         | system | NULL          | NULL | NULL    | NULL |    0 | const row not found |
     |  1 | PRIMARY     | <derived2> | system | NULL          | NULL | NULL    | NULL |    1 |                     |
     |  2 | DERIVED     | NULL       | NULL   | NULL          | NULL | NULL    | NULL | NULL | No tables used      |
     +----+-------------+------------+--------+---------------+------+---------+------+------+---------------------+
     3 rows in set (0.00 sec)

     mysql> SELECT * FROM t2;
     +------+
     | c1   |
     +------+
     |    5 |
     +------+
     1 row in set (0.00 sec)

This also means that an `EXPLAIN SELECT' statement such as the one
shown here may take a long time to execute:

     EXPLAIN SELECT * FROM t1 AS a1, (SELECT BENCHMARK(1000000, MD5(NOW())));

This is because the `BENCHMARK()' function is executed once for each
row in `t1'.


File: manual.info,  Node: subquery-errors,  Next: optimizing-subqueries,  Prev: unnamed-views,  Up: subqueries

12.2.8.9 Subquery Errors
........................

There are some errors that apply only to subqueries. This section
describes them.

   * Unsupported subquery syntax:

          ERROR 1235 (ER_NOT_SUPPORTED_YET)
          SQLSTATE = 42000
          Message = "This version of MySQL does not yet support
          'LIMIT & IN/ALL/ANY/SOME subquery'"

     This means that statements of the following form do not work yet:

          SELECT * FROM t1 WHERE s1 IN (SELECT s2 FROM t2 ORDER BY s1 LIMIT 1)

   * Incorrect number of columns from subquery:

          ERROR 1241 (ER_OPERAND_COL)
          SQLSTATE = 21000
          Message = "Operand should contain 1 column(s)"

     This error occurs in cases like this:

          SELECT (SELECT column1, column2 FROM t2) FROM t1;

     You may use a subquery that returns multiple columns, if the
     purpose is comparison. In other contexts, the subquery must be a
     scalar operand. See *Note row-subqueries::.

   * Incorrect number of rows from subquery:

          ERROR 1242 (ER_SUBSELECT_NO_1_ROW)
          SQLSTATE = 21000
          Message = "Subquery returns more than 1 row"

     This error occurs for statements where the subquery returns more
     than one row. Consider the following example:

          SELECT * FROM t1 WHERE column1 = (SELECT column1 FROM t2);

     If `SELECT column1 FROM t2' returns just one row, the previous
     query will work. If the subquery returns more than one row, error
     1242 will occur. In that case, the query should be rewritten as:

          SELECT * FROM t1 WHERE column1 = ANY (SELECT column1 FROM t2);

   * Incorrectly used table in subquery:

          Error 1093 (ER_UPDATE_TABLE_USED)
          SQLSTATE = HY000
          Message = "You can't specify target table 'x'
          for update in FROM clause"

     This error occurs in cases such as the following:

          UPDATE t1 SET column2 = (SELECT MAX(column1) FROM t1);

     You can use a subquery for assignment within an `UPDATE' statement
     because subqueries are legal in `UPDATE' and `DELETE' statements
     as well as in `SELECT' statements. However, you cannot use the
     same table (in this case, table `t1') for both the subquery's
     `FROM' clause and the update target.

For transactional storage engines, the failure of a subquery causes the
entire statement to fail. For non-transactional storage engines, data
modifications made before the error was encountered are preserved.


File: manual.info,  Node: optimizing-subqueries,  Next: rewriting-subqueries,  Prev: subquery-errors,  Up: subqueries

12.2.8.10 Optimizing Subqueries
...............................

Development is ongoing, so no optimization tip is reliable for the long
term. The following list provides some interesting tricks that you
might want to play with:

   * Use subquery clauses that affect the number or order of the rows
     in the subquery. For example:

          SELECT * FROM t1 WHERE t1.column1 IN
            (SELECT column1 FROM t2 ORDER BY column1);
          SELECT * FROM t1 WHERE t1.column1 IN
            (SELECT DISTINCT column1 FROM t2);
          SELECT * FROM t1 WHERE EXISTS
            (SELECT * FROM t2 LIMIT 1);

   * Replace a join with a subquery. For example, try this:

          SELECT DISTINCT column1 FROM t1 WHERE t1.column1 IN (
            SELECT column1 FROM t2);

     Instead of this:

          SELECT DISTINCT t1.column1 FROM t1, t2
            WHERE t1.column1 = t2.column1;

   * Some subqueries can be transformed to joins for compatibility with
     older versions of MySQL that do not support subqueries. However,
     in some cases, converting a subquery to a join may improve
     performance. See *Note rewriting-subqueries::.

   * Move clauses from outside to inside the subquery. For example, use
     this query:

          SELECT * FROM t1
            WHERE s1 IN (SELECT s1 FROM t1 UNION ALL SELECT s1 FROM t2);

     Instead of this query:

          SELECT * FROM t1
            WHERE s1 IN (SELECT s1 FROM t1) OR s1 IN (SELECT s1 FROM t2);

     For another example, use this query:

          SELECT (SELECT column1 + 5 FROM t1) FROM t2;

     Instead of this query:

          SELECT (SELECT column1 FROM t1) + 5 FROM t2;

   * Use a row subquery instead of a correlated subquery. For example,
     use this query:

          SELECT * FROM t1
            WHERE (column1,column2) IN (SELECT column1,column2 FROM t2);

     Instead of this query:

          SELECT * FROM t1
            WHERE EXISTS (SELECT * FROM t2 WHERE t2.column1=t1.column1
            AND t2.column2=t1.column2);

   * Use `NOT (a = ANY (...))' rather than `a <> ALL (...)'.

   * Use `x = ANY (TABLE CONTAINING (1,2))' rather than `x=1 OR x=2'.

   * Use `= ANY' rather than `EXISTS'.

   * For uncorrelated subqueries that always return one row, `IN' is
     always slower than `='. For example, use this query:

          SELECT * FROM t1 WHERE t1.COL_NAME
            = (SELECT a FROM t2 WHERE b = SOME_CONST);

     Instead of this query:

          SELECT * FROM t1 WHERE t1.COL_NAME
            IN (SELECT a FROM t2 WHERE b = SOME_CONST);

These tricks might cause programs to go faster or slower. Using MySQL
facilities like the `BENCHMARK()' function, you can get an idea about
what helps in your own situation. See *Note information-functions::.

Some optimizations that MySQL itself makes are:

   * MySQL executes uncorrelated subqueries only once. Use `EXPLAIN' to
     make sure that a given subquery really is uncorrelated.

   * MySQL rewrites `IN', `ALL', `ANY', and `SOME' subqueries in an
     attempt to take advantage of the possibility that the select-list
     columns in the subquery are indexed.

   * MySQL replaces subqueries of the following form with an
     index-lookup function, which `EXPLAIN' describes as a special join
     type (`unique_subquery' or `index_subquery'):

          ... IN (SELECT INDEXED_COLUMN FROM SINGLE_TABLE ...)

   * MySQL enhances expressions of the following form with an
     expression involving `MIN()' or `MAX()', unless `NULL' values or
     empty sets are involved:

          VALUE {ALL|ANY|SOME} {> | < | >= | <=} (UNCORRELATED SUBQUERY)

     For example, this `WHERE' clause:

          WHERE 5 > ALL (SELECT x FROM t)

     might be treated by the optimizer like this:

          WHERE 5 > (SELECT MAX(x) FROM t)

See also the MySQL Internals Manual chapter How MySQL Transforms
Subqueries
(http://forge.mysql.com/wiki/MySQL_Internals_Transformations).


File: manual.info,  Node: rewriting-subqueries,  Prev: optimizing-subqueries,  Up: subqueries

12.2.8.11 Rewriting Subqueries as Joins
.......................................

Although MySQL 5.1 supports subqueries (see *Note subqueries::), it is
still true that there are sometimes other ways to test membership in a
set of values. It is also true that on some occasions, it is not only
possible to rewrite a query without a subquery, but it can be more
efficient to make use of some of these techniques rather than to use
subqueries. One of these is the `IN()' construct:

For example, this query:

     SELECT * FROM t1 WHERE id IN (SELECT id FROM t2);

Can be rewritten as:

     SELECT DISTINCT t1.* FROM t1, t2 WHERE t1.id=t2.id;

The queries:

     SELECT * FROM t1 WHERE id NOT IN (SELECT id FROM t2);
     SELECT * FROM t1 WHERE NOT EXISTS (SELECT id FROM t2 WHERE t1.id=t2.id);

Can be rewritten as:

     SELECT table1.*
       FROM table1 LEFT JOIN table2 ON table1.id=table2.id
       WHERE table2.id IS NULL;

A `LEFT [OUTER] JOIN' can be faster than an equivalent subquery because
the server might be able to optimize it better -- a fact that is not
specific to MySQL Server alone. Prior to SQL-92, outer joins did not
exist, so subqueries were the only way to do certain things. Today,
MySQL Server and many other modern database systems offer a wide range
of outer join types.

MySQL Server supports multiple-table `DELETE' statements that can be
used to efficiently delete rows based on information from one table or
even from many tables at the same time. Multiple-table `UPDATE'
statements are also supported. See *Note delete::, and *Note update::.


File: manual.info,  Node: truncate,  Next: update,  Prev: subqueries,  Up: sql-syntax-data-manipulation

12.2.9 `TRUNCATE' Syntax
------------------------

     TRUNCATE [TABLE] TBL_NAME

`TRUNCATE TABLE' empties a table completely.  Logically, this is
equivalent to a `DELETE' statement that deletes all rows, but there are
practical differences under some circumstances.

For an `InnoDB' table, `InnoDB' processes `TRUNCATE TABLE' by deleting
rows one by one if there are any `FOREIGN KEY' constraints that
reference the table. If there are no `FOREIGN KEY' constraints,
`InnoDB' performs fast truncation by dropping the original table and
creating an empty one with the same definition, which is much faster
than deleting rows one by one. The `AUTO_INCREMENT' counter is reset by
`TRUNCATE TABLE', regardless of whether there is a `FOREIGN KEY'
constraint.

In the case that `FOREIGN KEY' constraints reference the table,
`InnoDB' deletes rows one by one and processes the constraints on each
one. If the `FOREIGN KEY' constraint specifies `DELETE CASCADE', rows
from the child (referenced) table are deleted, and the truncated table
becomes empty. If the `FOREIGN KEY' constraint does _not_ specify
`CASCADE', the `TRUNCATE' statement deletes rows one by one and stops
if it encounters a parent row that is referenced by the child,
returning this error:

     ERROR 1451 (23000): Cannot delete or update a parent row: a foreign
     key constraint fails (`test`.`child`, CONSTRAINT `child_ibfk_1`
     FOREIGN KEY (`parent_id`) REFERENCES `parent` (`id`))

This is the same as a `DELETE' statement with no `WHERE' clause.

The count of rows affected by `TRUNCATE TABLE' is accurate only when it
is mapped to a `DELETE' statement.

For other storage engines, `TRUNCATE TABLE' differs from `DELETE' in
the following ways in MySQL 5.1:

   * Truncate operations drop and re-create the table, which is much
     faster than deleting rows one by one, particularly for large
     tables.

   * Truncate operations are not transaction-safe; an error occurs when
     attempting one in the course of an active transaction or active
     table lock.

   * Truncation operations do not return the number of deleted rows.

   * As long as the table format file `TBL_NAME.frm' is valid, the
     table can be re-created as an empty table with `TRUNCATE TABLE',
     even if the data or index files have become corrupted.

   * The table handler does not remember the last used `AUTO_INCREMENT'
     value, but starts counting from the beginning. This is true even
     for `MyISAM' and `InnoDB', which normally do not reuse sequence
     values.

   * When used with partitioned tables, `TRUNCATE TABLE' preserves the
     partitioning; that is, the data and index files are dropped and
     re-created, while the partition definitions (`.par') file is
     unaffected.

   * Since truncation of a table does not make any use of `DELETE', the
     `TRUNCATE' statement does not invoke `ON DELETE' triggers.

`TRUNCATE TABLE' requires the `DROP' privilege as of MySQL 5.1.16.
(Before 5.1.16, it requires the `DELETE' privilege.


File: manual.info,  Node: update,  Prev: truncate,  Up: sql-syntax-data-manipulation

12.2.10 `UPDATE' Syntax
-----------------------

Single-table syntax:

     UPDATE [LOW_PRIORITY] [IGNORE] TBL_NAME
         SET COL_NAME1={EXPR1|DEFAULT} [, COL_NAME2={EXPR2|DEFAULT}] ...
         [WHERE WHERE_CONDITION]
         [ORDER BY ...]
         [LIMIT ROW_COUNT]

Multiple-table syntax:

     UPDATE [LOW_PRIORITY] [IGNORE] TABLE_REFERENCES
         SET COL_NAME1={EXPR1|DEFAULT} [, COL_NAME2={EXPR2|DEFAULT}] ...
         [WHERE WHERE_CONDITION]

For the single-table syntax, the `UPDATE' statement updates columns of
existing rows in `tbl_name' with new values. The `SET' clause indicates
which columns to modify and the values they should be given. Each value
can be given as an expression, or the keyword `DEFAULT' to set a column
explicitly to its default value. The `WHERE' clause, if given,
specifies the conditions that identify which rows to update. With no
`WHERE' clause, all rows are updated. If the `ORDER BY' clause is
specified, the rows are updated in the order that is specified. The
`LIMIT' clause places a limit on the number of rows that can be updated.

For the multiple-table syntax, `UPDATE' updates rows in each table
named in TABLE_REFERENCES that satisfy the conditions. In this case,
`ORDER BY' and `LIMIT' cannot be used.

WHERE_CONDITION is an expression that evaluates to true for each row to
be updated. It is specified as described in *Note select::.

The `UPDATE' statement supports the following modifiers:

   * If you use the `LOW_PRIORITY' keyword, execution of the `UPDATE'
     is delayed until no other clients are reading from the table. This
     affects only storage engines that use only table-level locking
     (`MyISAM', `MEMORY', `MERGE').

   * If you use the `IGNORE' keyword, the update statement does not
     abort even if errors occur during the update. Rows for which
     duplicate-key conflicts occur are not updated. Rows for which
     columns are updated to values that would cause data conversion
     errors are updated to the closest valid values instead.

If you access a column from TBL_NAME in an expression, `UPDATE' uses
the current value of the column. For example, the following statement
sets the `age' column to one more than its current value:

     UPDATE persondata SET age=age+1;

Single-table `UPDATE' assignments are generally evaluated from left to
right. For multiple-table updates, there is no guarantee that
assignments are carried out in any particular order.

If you set a column to the value it currently has, MySQL notices this
and does not update it.

If you update a column that has been declared `NOT NULL' by setting to
`NULL', the column is set to the default value appropriate for the data
type and the warning count is incremented. The default value is `0' for
numeric types, the empty string (`''') for string types, and the `zero'
value for date and time types.

`UPDATE' returns the number of rows that were actually changed. The
*Note `mysql_info()': mysql-info. C API function returns the number of
rows that were matched and updated and the number of warnings that
occurred during the `UPDATE'.

You can use `LIMIT ROW_COUNT' to restrict the scope of the `UPDATE'. A
`LIMIT' clause is a rows-matched restriction. The statement stops as
soon as it has found ROW_COUNT rows that satisfy the `WHERE' clause,
whether or not they actually were changed.

If an `UPDATE' statement includes an `ORDER BY' clause, the rows are
updated in the order specified by the clause. This can be useful in
certain situations that might otherwise result in an error. Suppose
that a table `t' contains a column `id' that has a unique index. The
following statement could fail with a duplicate-key error, depending on
the order in which rows are updated:

     UPDATE t SET id = id + 1;

For example, if the table contains 1 and 2 in the `id' column and 1 is
updated to 2 before 2 is updated to 3, an error occurs. To avoid this
problem, add an `ORDER BY' clause to cause the rows with larger `id'
values to be updated before those with smaller values:

     UPDATE t SET id = id + 1 ORDER BY id DESC;

You can also perform `UPDATE' operations covering multiple tables.
However, you cannot use `ORDER BY' or `LIMIT' with a multiple-table
`UPDATE'. The TABLE_REFERENCES clause lists the tables involved in the
join. Its syntax is described in *Note join::. Here is an example:

     UPDATE items,month SET items.price=month.price
     WHERE items.id=month.id;

The preceding example shows an inner join that uses the comma operator,
but multiple-table `UPDATE' statements can use any type of join allowed
in `SELECT' statements, such as `LEFT JOIN'.

You need the `UPDATE' privilege only for columns referenced in a
multiple-table `UPDATE' that are actually updated. You need only the
`SELECT' privilege for any columns that are read but not modified.

If you use a multiple-table `UPDATE' statement involving `InnoDB'
tables for which there are foreign key constraints, the MySQL optimizer
might process tables in an order that differs from that of their
parent/child relationship. In this case, the statement fails and rolls
back.  Instead, update a single table and rely on the `ON UPDATE'
capabilities that `InnoDB' provides to cause the other tables to be
modified accordingly. See *Note innodb-foreign-key-constraints::.

Currently, you cannot update a table and select from the same table in
a subquery.


File: manual.info,  Node: sql-syntax-utility,  Next: sql-syntax-transactions,  Prev: sql-syntax-data-manipulation,  Up: sql-syntax

12.3 MySQL Utility Statements
=============================

* Menu:

* describe::                     `DESCRIBE' Syntax
* explain::                      `EXPLAIN' Syntax
* help::                         `HELP' Syntax
* use::                          `USE' Syntax


File: manual.info,  Node: describe,  Next: explain,  Prev: sql-syntax-utility,  Up: sql-syntax-utility

12.3.1 `DESCRIBE' Syntax
------------------------

     {DESCRIBE | DESC} TBL_NAME [COL_NAME | WILD]

`DESCRIBE' provides information about the columns in a table. It is a
shortcut for `SHOW COLUMNS FROM'. These statements also display
information for views. (See *Note show-columns::.)

COL_NAME can be a column name, or a string containing the SQL ``%'' and
``_'' wildcard characters to obtain output only for the columns with
names matching the string. There is no need to enclose the string
within quotes unless it contains spaces or other special characters.

     mysql> DESCRIBE City;
     +------------+----------+------+-----+---------+----------------+
     | Field      | Type     | Null | Key | Default | Extra          |
     +------------+----------+------+-----+---------+----------------+
     | Id         | int(11)  | NO   | PRI | NULL    | auto_increment |
     | Name       | char(35) | NO   |     |         |                |
     | Country    | char(3)  | NO   | UNI |         |                |
     | District   | char(20) | YES  | MUL |         |                |
     | Population | int(11)  | NO   |     | 0       |                |
     +------------+----------+------+-----+---------+----------------+
     5 rows in set (0.00 sec)

The description for `SHOW COLUMNS' provides more information about the
output columns (see *Note show-columns::).

If the data types differ from what you expect them to be based on a
`CREATE TABLE' statement, note that MySQL sometimes changes data types
when you create or alter a table. The conditions under which this
occurs are described in *Note silent-column-changes::.

The `DESCRIBE' statement is provided for compatibility with Oracle.

The `SHOW CREATE TABLE', `SHOW TABLE STATUS', and `SHOW INDEX'
statements also provide information about tables. See *Note show::.


File: manual.info,  Node: explain,  Next: help,  Prev: describe,  Up: sql-syntax-utility

12.3.2 `EXPLAIN' Syntax
-----------------------

     EXPLAIN TBL_NAME

Or:

     EXPLAIN [EXTENDED | PARTITIONS] SELECT SELECT_OPTIONS

The `EXPLAIN' statement can be used either as a synonym for `DESCRIBE'
or as a way to obtain information about how MySQL executes a `SELECT'
statement:

   * `EXPLAIN TBL_NAME' is synonymous with `DESCRIBE TBL_NAME' or `SHOW
     COLUMNS FROM TBL_NAME'.

     For a description of the `DESCRIBE' and `SHOW COLUMNS' statements,
     see *Note describe::, and *Note show-columns::.

   * When you precede a `SELECT' statement with the keyword `EXPLAIN',
     MySQL displays information from the optimizer about the query
     execution plan.  That is, MySQL explains how it would process the
     `SELECT', including information about how tables are joined and in
     which order.

     For information regarding the use of `EXPLAIN' for obtaining query
     execution plan information, see *Note using-explain::.

   * `EXPLAIN PARTITIONS' is available beginning with MySQL 5.1.5. It
     is useful only when examining queries involving partitioned tables.

     For details, see *Note partitioning-info::.


File: manual.info,  Node: help,  Next: use,  Prev: explain,  Up: sql-syntax-utility

12.3.3 `HELP' Syntax
--------------------

     HELP 'SEARCH_STRING'

The `HELP' statement returns online information from the MySQL
Reference manual. Its proper operation requires that the help tables in
the `mysql' database be initialized with help topic information (see
*Note server-side-help-support::).

The `HELP' statement searches the help tables for the given search
string and displays the result of the search. The search string is not
case sensitive.

The HELP statement understands several types of search strings:

   * At the most general level, use `contents' to retrieve a list of
     the top-level help categories:

          HELP 'contents'

   * For a list of topics in a given help category, such as `Data
     Types', use the category name:

          HELP 'data types'

   * For help on a specific help topic, such as the `ASCII()' function
     or the `CREATE TABLE' statement, use the associated keyword or
     keywords:

          HELP 'ascii'
          HELP 'create table'

In other words, the search string matches a category, many topics, or a
single topic. You cannot necessarily tell in advance whether a given
search string will return a list of items or the help information for a
single help topic. However, you can tell what kind of response `HELP'
returned by examining the number of rows and columns in the result set.

The following descriptions indicate the forms that the result set can
take. Output for the example statements is shown using the familar
`tabular' or `vertical' format that you see when using the `mysql'
client, but note that `mysql' itself reformats `HELP' result sets in a
different way.

   * Empty result set

     No match could be found for the search string.

   * Result set containing a single row with three columns

     This means that the search string yielded a hit for the help
     topic. The result has three columns:

        * `name': The topic name.

        * `description': Descriptive help text for the topic.

        * `example': Usage example or exmples. This column might be
          blank.

     Example: `HELP 'replace''

     Yields:

          name: REPLACE
          description: Syntax:
          REPLACE(str,from_str,to_str)

          Returns the string str with all occurrences of the string from_str
          replaced by the string to_str. REPLACE() performs a case-sensitive
          match when searching for from_str.
          example: mysql> SELECT REPLACE('www.mysql.com', 'w', 'Ww');
                  -> 'WwWwWw.mysql.com'

   * Result set containing multiple rows with two columns

     This means that the search string matched many help topics.  The
     result set indicates the help topic names:

        * `name': The help topic name.

        * `is_it_category': `Y' if the name represents a help category,
          `N' if it does not. If it does not, the `name' value when
          specified as the argument to the `HELP' statement should
          yield a single-row result set containing a description for
          the named item.

     Example: `HELP 'status''

     Yields:

          +-----------------------+----------------+
          | name                  | is_it_category |
          +-----------------------+----------------+
          | SHOW                  | N              |
          | SHOW ENGINE           | N              |
          | SHOW INNODB STATUS    | N              |
          | SHOW MASTER STATUS    | N              |
          | SHOW PROCEDURE STATUS | N              |
          | SHOW SLAVE STATUS     | N              |
          | SHOW STATUS           | N              |
          | SHOW TABLE STATUS     | N              |
          +-----------------------+----------------+

   * Result set containing multiple rows with three columns

     This means the search string matches a category. The result set
     contains category entries:

        * `source_category_name': The help category name.

        * `name': The category or topic name

        * `is_it_category': `Y' if the name represents a help category,
          `N' if it does not. If it does not, the `name' value when
          specified as the argument to the `HELP' statement should
          yield a single-row result set containing a description for
          the named item.

     Example: `HELP 'functions''

     Yields:

          +----------------------+-------------------------+----------------+
          | source_category_name | name                    | is_it_category |
          +----------------------+-------------------------+----------------+
          | Functions            | CREATE FUNCTION         | N              |
          | Functions            | DROP FUNCTION           | N              |
          | Functions            | Bit Functions           | Y              |
          | Functions            | Comparison operators    | Y              |
          | Functions            | Control flow functions  | Y              |
          | Functions            | Date and Time Functions | Y              |
          | Functions            | Encryption Functions    | Y              |
          | Functions            | Information Functions   | Y              |
          | Functions            | Logical operators       | Y              |
          | Functions            | Miscellaneous Functions | Y              |
          | Functions            | Numeric Functions       | Y              |
          | Functions            | String Functions        | Y              |
          +----------------------+-------------------------+----------------+

Before MySQL 5.1.17, if you intend to use the `HELP' statement while
other tables are locked with `LOCK TABLES', you must also lock the
required `mysql.help_XXX' tables. See *Note lock-tables::.


File: manual.info,  Node: use,  Prev: help,  Up: sql-syntax-utility

12.3.4 `USE' Syntax
-------------------

     USE DB_NAME

The `USE DB_NAME' statement tells MySQL to use the DB_NAME database as
the default (current) database for subsequent statements. The database
remains the default until the end of the session or another `USE'
statement is issued:

     USE db1;
     SELECT COUNT(*) FROM mytable;   # selects from db1.mytable
     USE db2;
     SELECT COUNT(*) FROM mytable;   # selects from db2.mytable

Making a particular database the default by means of the `USE'
statement does not preclude you from accessing tables in other
databases. The following example accesses the `author' table from the
`db1' database and the `editor' table from the `db2' database:

     USE db1;
     SELECT author_name,editor_name FROM author,db2.editor
       WHERE author.editor_id = db2.editor.editor_id;

The `USE' statement is provided for compatibility with Sybase.


File: manual.info,  Node: sql-syntax-transactions,  Next: sql-syntax-server-administration,  Prev: sql-syntax-utility,  Up: sql-syntax

12.4 MySQL Transactional and Locking Statements
===============================================

* Menu:

* commit::                       `START TRANSACTION', `COMMIT', and `ROLLBACK' Syntax
* cannot-roll-back::             Statements That Cannot Be Rolled Back
* implicit-commit::              Statements That Cause an Implicit Commit
* savepoints::                   `SAVEPOINT' and `ROLLBACK TO SAVEPOINT' Syntax
* lock-tables::                  `LOCK TABLES' and `UNLOCK TABLES' Syntax
* set-transaction::              `SET TRANSACTION' Syntax
* xa::                           XA Transactions

MySQL supports local transactions (within a given client connection)
through statements such as `SET AUTOCOMMIT', `START TRANSACTION',
`COMMIT', and `ROLLBACK'. See *Note commit::. XA transaction support
enables MySQL to participate in distributed transactions as well. See
*Note xa::.


File: manual.info,  Node: commit,  Next: cannot-roll-back,  Prev: sql-syntax-transactions,  Up: sql-syntax-transactions

12.4.1 `START TRANSACTION', `COMMIT', and `ROLLBACK' Syntax
-----------------------------------------------------------

     START TRANSACTION [WITH CONSISTENT SNAPSHOT] | BEGIN [WORK]
     COMMIT [WORK] [AND [NO] CHAIN] [[NO] RELEASE]
     ROLLBACK [WORK] [AND [NO] CHAIN] [[NO] RELEASE]
     SET AUTOCOMMIT = {0 | 1}

The `START TRANSACTION' and `BEGIN' statement begin a new transaction.
`COMMIT' commits the current transaction, making its changes permanent.
`ROLLBACK' rolls back the current transaction, canceling its changes.
The `SET AUTOCOMMIT' statement disables or enables the default
autocommit mode for the current connection.

The optional `WORK' keyword is supported for `COMMIT' and `ROLLBACK',
as are the `CHAIN' and `RELEASE' clauses. `CHAIN' and `RELEASE' can be
used for additional control over transaction completion.  The value of
the `completion_type' system variable determines the default completion
behavior. See *Note server-system-variables::.

The `AND CHAIN' clause causes a new transaction to begin as soon as the
current one ends, and the new transaction has the same isolation level
as the just-terminated transaction.  The `RELEASE' clause causes the
server to disconnect the current client connection after terminating the
current transaction. Including the `NO' keyword suppresses `CHAIN' or
`RELEASE' completion, which can be useful if the `completion_type'
system variable is set to cause chaining or release completion by
default.

By default, MySQL runs with autocommit mode enabled. This means that as
soon as you execute a statement that updates (modifies) a table, MySQL
stores the update on disk.

If you are using a transaction-safe storage engine (such as `InnoDB',
or `NDBCLUSTER'), you can disable autocommit mode with the following
statement:

     SET AUTOCOMMIT=0;

After disabling autocommit mode by setting the `AUTOCOMMIT' variable to
zero, you must use `COMMIT' to store your changes to disk or `ROLLBACK'
if you want to ignore the changes you have made since the beginning of
your transaction.

To disable autocommit mode for a single series of statements, use the
`START TRANSACTION' statement:

     START TRANSACTION;
     SELECT @A:=SUM(salary) FROM table1 WHERE type=1;
     UPDATE table2 SET summary=@A WHERE type=1;
     COMMIT;

With `START TRANSACTION', autocommit remains disabled until you end the
transaction with `COMMIT' or `ROLLBACK'. The autocommit mode then
reverts to its previous state.

`BEGIN' and `BEGIN WORK' are supported as aliases of `START
TRANSACTION' for initiating a transaction. `START TRANSACTION' is
standard SQL syntax and is the recommended way to start an ad-hoc
transaction.

*Important*:

Many APIs used for writing MySQL client applications (such as JDBC)
provide their own methods for starting transactions that can (and
sometimes should) be used instead of sending a `START TRANSACTION'
statement from the client.  See *Note apis::, or the documentation for
your API, for more information.

The `BEGIN' statement differs from the use of the `BEGIN' keyword that
starts a `BEGIN ...  END' compound statement. The latter does not begin
a transaction. See *Note begin-end::.

You can also begin a transaction like this:

     START TRANSACTION WITH CONSISTENT SNAPSHOT;

The `WITH CONSISTENT SNAPSHOT' clause starts a consistent read for
storage engines that are capable of it. This applies only to `InnoDB'.
The effect is the same as issuing a `START TRANSACTION' followed by a
`SELECT' from any `InnoDB' table. See *Note innodb-consistent-read::.
The `WITH CONSISTENT SNAPSHOT' clause does not change the current
transaction isolation level, so it provides a consistent snapshot only
if the current isolation level is one that allows consistent read
(`REPEATABLE READ' or `SERIALIZABLE').

Beginning a transaction causes any pending transaction to be committed.
See *Note implicit-commit::, for more information.

Beginning a transaction also causes table locks acquired with `LOCK
TABLES' to be released, as though you had executed `UNLOCK TABLES'.
Beginning a transaction does not release a global read lock acquired
with `FLUSH TABLES WITH READ LOCK'.

For best results, transactions should be performed using only tables
managed by a single transactional storage engine.  Otherwise, the
following problems can occur:

   * If you use tables from more than one transaction-safe storage
     engine (such as `InnoDB' and `Falcon'), and the transaction
     isolation level is not `SERIALIZABLE', it is possible that when
     one transaction commits, another ongoing transaction that uses the
     same tables will see only some of the changes made by the first
     transaction. That is, the atomicity of transactions is not
     guaranteed with mixed engines and inconsistencies can result. (If
     mixed-engine transactions are infrequent, you can use `SET
     TRANSACTION ISOLATION LEVEL' to set the isolation level to
     `SERIALIZABLE' on a per-transaction basis as necessary.)

   * If you use non-transaction-safe tables within a transaction, any
     changes to those tables are stored at once, regardless of the
     status of autocommit mode.

     If you issue a `ROLLBACK' statement after updating a
     non-transactional table within a transaction, an
     `ER_WARNING_NOT_COMPLETE_ROLLBACK' warning occurs. Changes to
     transaction-safe tables are rolled back, but not changes to
     non-transaction-safe tables.

Each transaction is stored in the binary log in one chunk, upon
`COMMIT'. Transactions that are rolled back are not logged.
(*Exception*: Modifications to non-transactional tables cannot be
rolled back.  If a transaction that is rolled back includes
modifications to non-transactional tables, the entire transaction is
logged with a `ROLLBACK' statement at the end to ensure that the
modifications to those tables are replicated.) See *Note binary-log::.

You can change the isolation level for transactions with `SET
TRANSACTION ISOLATION LEVEL'. See *Note set-transaction::.

Rolling back can be a slow operation that may occur without the user
having explicitly asked for it (for example, when an error occurs).
Because of this, `SHOW PROCESSLIST' displays `Rolling back' in the
`State' column for the connection during implicit and explicit
(`ROLLBACK' SQL statement) rollbacks.


File: manual.info,  Node: cannot-roll-back,  Next: implicit-commit,  Prev: commit,  Up: sql-syntax-transactions

12.4.2 Statements That Cannot Be Rolled Back
--------------------------------------------

Some statements cannot be rolled back. In general, these include data
definition language (DDL) statements, such as those that create or drop
databases, those that create, drop, or alter tables or stored routines.

You should design your transactions not to include such statements. If
you issue a statement early in a transaction that cannot be rolled
back, and then another statement later fails, the full effect of the
transaction cannot be rolled back in such cases by issuing a `ROLLBACK'
statement.


File: manual.info,  Node: implicit-commit,  Next: savepoints,  Prev: cannot-roll-back,  Up: sql-syntax-transactions

12.4.3 Statements That Cause an Implicit Commit
-----------------------------------------------

Each of the following statements (and any synonyms for them) implicitly
end a transaction, as if you had done a `COMMIT' before executing the
statement:

   * `ALTER EVENT', `ALTER FUNCTION', `ALTER PROCEDURE', `ALTER TABLE',
     `BEGIN', `CREATE DATABASE', `CREATE EVENT', `CREATE FUNCTION',
     `CREATE INDEX', `CREATE PROCEDURE', `CREATE TABLE', `DROP
     DATABASE', `DROP EVENT', `DROP FUNCTION', `DROP INDEX', `DROP
     PROCEDURE', `DROP TABLE', `LOAD DATA INFILE' `LOCK TABLES',
     `RENAME TABLE', `SET AUTOCOMMIT=1' (if the value is not already
     1), `START TRANSACTION', `TRUNCATE TABLE', `UNLOCK TABLES'.

     The `BEGIN' statement differs from the use of the `BEGIN' keyword
     that starts a `BEGIN ... END' compound statement. The latter does
     not cause an implicit commit. See *Note begin-end::.

   * Beginning with MySQL 5.1.3, `ALTER VIEW', `CREATE TRIGGER', `CREATE
     USER', `CREATE VIEW', `DROP TRIGGER', `DROP USER', `DROP VIEW',
     and `RENAME USER' cause an implicit commit.

   * `UNLOCK TABLES' commits a transaction only if any tables currently
     have been locked with `LOCK TABLES'. This does not occur for
     `UNLOCK TABLES' following `FLUSH TABLES WITH READ LOCK' because
     the latter statement does not acquire table-level locks.

   * The `CREATE TABLE' statement in `InnoDB' is processed as a single
     transaction. This means that a `ROLLBACK' from the user does not
     undo `CREATE TABLE' statements the user made during that
     transaction.

   * `CREATE TABLE' and `DROP TABLE' do not commit a transaction if the
     `TEMPORARY' keyword is used. (This does not apply to other
     operations on temporary tables such as `CREATE INDEX', which do
     cause a commit.)  However, although no implicit commit occurs,
     neither can the statement be rolled back. Therefore, use of such
     statements will violate transaction atomicity: For example, if you
     use `CREATE TEMPORARY TABLE' and then roll back the transaction,
     the table remains in existence.

   * In MySQL 5.1.11 and earlier, `LOAD DATA INFILE' caused an implicit
     commit for all storage engines. Beginning with MySQL 5.1.12, it
     causes an implicit commit only for tables using the `NDB' storage
     engine. For more information, see Bug#11151
     (http://bugs.mysql.com/11151).

   * Beginning with MySQL 5.1.15, `CREATE TABLE ...  SELECT' causes an
     implicit commit before and after the statement is executed when
     you are creating non-temporary tables. (No commit occurs for
     `CREATE TEMPORARY TABLE ... SELECT'.) This is to prevent an issue
     during replication where the table could be created on the master
     after a rollback, but fail to be recorded in the binary log, and
     therefore not replicated to the slave. For more information, see
     Bug#22865 (http://bugs.mysql.com/22865).

   * Beginning with MySQL 5.1.23, `GRANT', `REVOKE', and `SET PASSWORD'
     statements cause an implicit commit.

Transactions cannot be nested. This is a consequence of the implicit
`COMMIT' performed for any current transaction when you issue a `START
TRANSACTION' statement or one of its synonyms.

Statements that cause an implicit commit cannot be used in an XA
transaction while the transaction is in an `ACTIVE' state.


File: manual.info,  Node: savepoints,  Next: lock-tables,  Prev: implicit-commit,  Up: sql-syntax-transactions

12.4.4 `SAVEPOINT' and `ROLLBACK TO SAVEPOINT' Syntax
-----------------------------------------------------

     SAVEPOINT IDENTIFIER
     ROLLBACK [WORK] TO [SAVEPOINT] IDENTIFIER
     RELEASE SAVEPOINT IDENTIFIER

`InnoDB' supports the SQL statements `SAVEPOINT', `ROLLBACK TO
SAVEPOINT', `RELEASE SAVEPOINT' and the optional `WORK' keyword for
`ROLLBACK'.

The `SAVEPOINT' statement sets a named transaction savepoint with a
name of IDENTIFIER. If the current transaction has a savepoint with the
same name, the old savepoint is deleted and a new one is set.

The `ROLLBACK TO SAVEPOINT' statement rolls back a transaction to the
named savepoint. Modifications that the current transaction made to
rows after the savepoint was set are undone in the rollback, but
`InnoDB' does _not_ release the row locks that were stored in memory
after the savepoint. (Note that for a new inserted row, the lock
information is carried by the transaction ID stored in the row; the
lock is not separately stored in memory. In this case, the row lock is
released in the undo.) Savepoints that were set at a later time than
the named savepoint are deleted.

If the `ROLLBACK TO SAVEPOINT' statement returns the following error,
it means that no savepoint with the specified name exists:

     ERROR 1181: Got error 153 during ROLLBACK

The `RELEASE SAVEPOINT' statement removes the named savepoint from the
set of savepoints of the current transaction. No commit or rollback
occurs. It is an error if the savepoint does not exist.

All savepoints of the current transaction are deleted if you execute a
`COMMIT', or a `ROLLBACK' that does not name a savepoint.

A new savepoint level is created when a stored function is invoked or a
trigger is activated. The savepoints on previous levels become
unavailable and thus do not conflict with savepoints on the new level.
When the function or trigger terminates, any savepoints it created are
released and the previous savepoint level is restored.


File: manual.info,  Node: lock-tables,  Next: set-transaction,  Prev: savepoints,  Up: sql-syntax-transactions

12.4.5 `LOCK TABLES' and `UNLOCK TABLES' Syntax
-----------------------------------------------

     LOCK TABLES
         TBL_NAME [[AS] ALIAS] LOCK_TYPE
         [, TBL_NAME [[AS] ALIAS] LOCK_TYPE] ...

     LOCK_TYPE:
         READ [LOCAL]
       | [LOW_PRIORITY] WRITE

     UNLOCK TABLES

MySQL enables client sessions to acquire table locks explicitly for the
purpose of cooperating with other sessions for access to tables, or to
prevent other sessions from modifying tables during periods when a
session requires exclusive access to them. A session can acquire or
release locks only for itself. One session cannot acquire locks for
another session or release locks held by another session.

`LOCK TABLES' acquires table locks for the current thread. It locks
base tables or views. (For view locking, `LOCK TABLES' adds all base
tables used in the view to the set of tables to be locked and locks them
automatically.) To use `LOCK TABLES', you must have the `LOCK TABLES'
privilege, and the `SELECT' privilege for each object to be locked.

MySQL enables client sessions to acquire table locks explicitly Locks
may be used to emulate transactions or to get more speed when updating
tables. This is explained in more detail later in this section.

`UNLOCK TABLES' explicitly releases any table locks held by the current
thread. Another use for `UNLOCK TABLES' is to release the global read
lock acquired with `FLUSH TABLES WITH READ LOCK'. (You can lock all
tables in all databases with a read lock with the `FLUSH TABLES WITH
READ LOCK' statement. See *Note flush::. This is a very convenient way
to get backups if you have a filesystem such as Veritas that can take
snapshots in time.)

The following discussion applies only to non-`TEMPORARY' tables. `LOCK
TABLES' is allowed (but ignored) for a `TEMPORARY' table. The table can
be accessed freely by the session within which it was created,
regardless of what other locking may be in effect. No lock is necessary
because no other session can see the table.

The following general rules apply to acquisition and release of locks
by a given thread:

   * Table locks are acquired with `LOCK TABLES'.

   * If the `LOCK TABLES' statement must wait due to locks held by
     other threads on any of the tables, it blocks until all locks can
     be acquired.

   * Table locks are released explicitly with `UNLOCK TABLES'.

   * Table locks are released implicitly under these conditions:

        * `LOCK TABLES' releases any table locks currently held by the
          thread before acquiring new locks.

        * Beginning a transaction (for example, with `START
          TRANSACTION') implicitly performs an `UNLOCK TABLES'.
          (Additional information about the interaction between table
          locking and transactions is given later in this section.)

        * If a client connection drops, the server releases table locks
          held by the client. If the client reconnects, the locks will
          no longer be in effect. In addition, if the client had an
          active transaction, the server rolls back the transaction
          upon disconnect, and if reconnect occurs, the new session
          begins with autocommit enabled. For this reason, clients may
          wish to disable auto-reconnect. With auto-reconnect in
          effect, the client is not notified if reconnect occurs but
          any table locks or current transaction will have been lost.
          With auto-reconnect disabled, if the connection drops, an
          error occurs for the next statement issued. The client can
          detect the error and take appropriate action such as
          reacquiring the locks or redoing the transaction. See *Note
          auto-reconnect::.

*Note*:

If you use `ALTER TABLE' on a locked table, it may become unlocked. See
*Note alter-table-problems::.

A table lock protects only against inappropriate reads or writes by
other clients. The client holding the lock, even a read lock, can
perform table-level operations such as `DROP TABLE'. Truncate
operations are not transaction-safe, so an error occurs if the client
attempts one during an active transaction or while holding a table lock.

When you use `LOCK TABLES', you must lock all tables that you are going
to use in your statements. While the locks obtained with a `LOCK
TABLES' statement are in effect, you cannot access any tables that were
not locked by the statement. If you lock a view, `LOCK TABLES' adds all
base tables used in the view to the set of tables to be locked and
locks them automatically.

You cannot refer to a locked table multiple times in a single query
using the same name. Use aliases instead, and obtain a separate lock
for the table and each alias:

     mysql> LOCK TABLE t WRITE, t AS t1 READ;
     mysql> INSERT INTO t SELECT * FROM t;
     ERROR 1100: Table 't' was not locked with LOCK TABLES
     mysql> INSERT INTO t SELECT * FROM t AS t1;

The error occurs for the first `INSERT' because there are two
references to the same name for a locked table. The second `INSERT'
succeeds because the references to the table use different names.

If your statements refer to a table by means of an alias, you must lock
the table using that same alias. It does not work to lock the table
without specifying the alias:

     mysql> LOCK TABLE t READ;
     mysql> SELECT * FROM t AS myalias;
     ERROR 1100: Table 'myalias' was not locked with LOCK TABLES

Conversely, if you lock a table using an alias, you must refer to it in
your statements using that alias:

     mysql> LOCK TABLE t AS myalias READ;
     mysql> SELECT * FROM t;
     ERROR 1100: Table 't' was not locked with LOCK TABLES
     mysql> SELECT * FROM t AS myalias;

If a thread obtains a `READ' lock on a table, that thread (and all
other threads) can only read from the table.  If a thread obtains a
`WRITE' lock on a table, only the thread holding the lock can write to
the table (that thread can also read from the table); other threads are
blocked from reading or writing the table until the lock has been
released.

The difference between `READ' and `READ LOCAL' is that `READ LOCAL'
allows non-conflicting `INSERT' statements (concurrent inserts) to
execute while the lock is held. However, `READ LOCAL' cannot be used if
you are going to manipulate the database using processes external to
the server while you hold the lock. For `InnoDB' tables, `READ LOCAL'
is the same as `READ'.

`WRITE' locks normally have higher priority than `READ' locks to ensure
that updates are processed as soon as possible. This means that if one
thread obtains a `READ' lock and then another thread requests a `WRITE'
lock, subsequent `READ' lock requests wait until the thread that
requested the `WRITE' lock has obtained the lock and released it. A
request for a `LOW_PRIORITY WRITE' lock, by contrast, allows subsequent
`READ' lock requests by other threads to be satisfied first if they
occur while the `LOW_PRIORITY WRITE' request is waiting. You should use
`LOW_PRIORITY WRITE' locks only if you are sure that eventually there
will be a time when no threads have a `READ' lock. For `InnoDB' tables
in transactional mode (autocommit = 0), a waiting `LOW_PRIORITY WRITE'
lock acts like a regular `WRITE' lock and causes subsequent `READ' lock
requests to wait.

`LOCK TABLES' works as follows:

  1. Sort all tables to be locked in an internally defined order.  From
     the user standpoint, this order is undefined.

  2. If a table is to be locked with a read and a write lock, put the
     write lock request before the read lock request.

  3. Lock one table at a time until the thread gets all locks.

This policy ensures that table locking is deadlock free. There are,
however, other things you need to be aware of about this policy: If you
are using a `LOW_PRIORITY WRITE' lock for a table, it means only that
MySQL waits for this particular lock until there are no other threads
that want a `READ' lock. When the thread has gotten the `WRITE' lock
and is waiting to get the lock for the next table in the lock table
list, all other threads wait for the `WRITE' lock to be released. If
this becomes a serious problem with your application, you should
consider converting some of your tables to transaction-safe tables.

`LOCK TABLES' and `UNLOCK TABLES' interact with the use of transactions
as follows:

   * `LOCK TABLES' is not transaction-safe and implicitly commits any
     active transaction before attempting to lock the tables.

   * `UNLOCK TABLES' implicitly commits any active transaction, but
     only if `LOCK TABLES' has been used to acquire table locks. For
     example, in the following set of statements, `UNLOCK TABLES'
     releases the global read lock but does not commit the transaction
     because no table locks are in effect:

          FLUSH TABLES WITH READ LOCK;
          START TRANSACTION;
          SELECT ... ;
          UNLOCK TABLES;

   * Beginning a transaction (for example, with `START TRANSACTION')
     implicitly commits any current transaction and releases existing
     locks.

   * Other statements that implicitly cause transactions to be
     committed do not release existing locks. For a list of such
     statements, see *Note implicit-commit::.

   * The correct way to use `LOCK TABLES' and `UNLOCK TABLES' with
     transactional tables, such as `InnoDB' tables, is to begin a
     transaction with `SET AUTOCOMMIT = 0' (not `START TRANSACTION')
     followed by `LOCK TABLES', and to not call `UNLOCK TABLES' until
     you commit the transaction explicitly. When you call `LOCK
     TABLES', `InnoDB' internally takes its own table lock, and MySQL
     takes its own table lock.  `InnoDB' releases its internal table
     lock at the next commit, but for MySQL to release its table lock,
     you have to call `UNLOCK TABLES'. You should not have `AUTOCOMMIT
     = 1', because then `InnoDB' releases its internal table lock
     immediately after the call of `LOCK TABLES', and deadlocks can
     very easily happen.  `InnoDB' does not acquire the internal table
     lock at all if `AUTOCOMMIT=1', to help old applications avoid
     unnecessary deadlocks.

   * `ROLLBACK' does not release table locks.

   * `FLUSH TABLES WITH READ LOCK' acquires a global read lock and not
     table locks, so it is not subject to the same behavior as `LOCK
     TABLES' and `UNLOCK TABLES' with respect to table locking and
     implicit commits. See *Note flush::.

You can safely use `KILL' to terminate a thread that is waiting for a
table lock. See *Note kill::.

You should _not_ lock any tables that you are using with `INSERT
DELAYED' because in that case the `INSERT' is performed by a separate
thread.

For some operations, system tables in the `mysql' database must be
accessed. For example, the `HELP' statement requires the contents of the
server-side help tables, and `CONVERT_TZ()' might need to read the time
zone tables. Before MySQL 5.1.17, to perform such operations while a
`LOCK TABLES' statement is in effect, you must also lock the requisite
system tables explicitly or a lock error occurs. As of 5.1.17, the
server implicitly locks the system tables for reading as necessary so
that you need not lock them explicitly. These tables are treated as
just described:

     mysql.help_category
     mysql.help_keyword
     mysql.help_relation
     mysql.help_topic
     mysql.proc
     mysql.time_zone
     mysql.time_zone_leap_second
     mysql.time_zone_name
     mysql.time_zone_transition
     mysql.time_zone_transition_type

If you want to explicitly place a `WRITE' lock on any of those tables
with a `LOCK TABLES' statement, the table must be the only one locked;
no other table can be locked with the same statement.

Normally, you do not need to lock tables, because all single `UPDATE'
statements are atomic; no other thread can interfere with any other
currently executing SQL statement.  However, there are a few cases when
locking tables may provide an advantage:

   * If you are going to run many operations on a set of `MyISAM'
     tables, it is much faster to lock the tables you are going to use.
     Locking `MyISAM' tables speeds up inserting, updating, or deleting
     on them because MySQL does not flush the key cache for the locked
     tables until `UNLOCK TABLES' is called. Normally, the key cache is
     flushed after each SQL statement.

     The downside to locking the tables is that no thread can update a
     `READ'-locked table (including the one holding the lock) and no
     thread can access a `WRITE'-locked table other than the one
     holding the lock.

   * If you are using tables for a non-transactional storage engine,
     you must use `LOCK TABLES' if you want to ensure that no other
     thread modifies the tables between a `SELECT' and an `UPDATE'. The
     example shown here requires `LOCK TABLES' to execute safely:

          LOCK TABLES trans READ, customer WRITE;
          SELECT SUM(value) FROM trans WHERE customer_id=SOME_ID;
          UPDATE customer
            SET total_value=SUM_FROM_PREVIOUS_STATEMENT
            WHERE customer_id=SOME_ID;
          UNLOCK TABLES;

     Without `LOCK TABLES', it is possible that another thread might
     insert a new row in the `trans' table between execution of the
     `SELECT' and `UPDATE' statements.

You can avoid using `LOCK TABLES' in many cases by using relative
updates (`UPDATE customer SET VALUE=VALUE+NEW_VALUE') or the
`LAST_INSERT_ID()' function.  See *Note ansi-diff-transactions::.

You can also avoid locking tables in some cases by using the user-level
advisory lock functions `GET_LOCK()' and `RELEASE_LOCK()'. These locks
are saved in a hash table in the server and implemented with
`pthread_mutex_lock()' and `pthread_mutex_unlock()' for high speed. See
*Note miscellaneous-functions::.

See *Note internal-locking::, for more information on locking policy.


File: manual.info,  Node: set-transaction,  Next: xa,  Prev: lock-tables,  Up: sql-syntax-transactions

12.4.6 `SET TRANSACTION' Syntax
-------------------------------

     SET [GLOBAL | SESSION] TRANSACTION ISOLATION LEVEL
       {
            READ UNCOMMITTED
          | READ COMMITTED
          | REPEATABLE READ
          | SERIALIZABLE
        }

This statement sets the transaction isolation level for the next
transaction, globally, or for the current session.

The default behavior of `SET TRANSACTION' is to set the isolation level
for the next (not yet started) transaction. If you use the `GLOBAL'
keyword, the statement sets the default transaction level globally for
all new connections created from that point on. Existing connections are
unaffected. You need the `SUPER' privilege to do this. Using the
`SESSION' keyword sets the default transaction level for all future
transactions performed on the current connection.

For information about `InnoDB' and transaction isolation level, see
*Note innodb-transaction-isolation::.  `InnoDB' supports each of the
levels described here in MySQL 5.1. The default level is `REPEATABLE
READ'. See also *Note innodb-locks-set::, for additional information
about how `InnoDB' uses locks to execute various types of statements.

In MySQL 5.1, if the `READ COMMITTED' isolation level is used or the
`innodb_locks_unsafe_for_binlog' system variable is enabled, there is
no `InnoDB' gap locking except in constraint checking. Also, record
locks for non-matching rows are released after MySQL has evaluated the
`WHERE' condition.

To set the initial default global isolation level for `mysqld', use the
`--transaction-isolation' option. See *Note server-options::.

A detailed list of the transaction levels supported by MySQL and the
various storage engines follows:

   * `READ UNCOMMITTED'

     `SELECT' statements are performed in a non-locking fashion, but a
     possible earlier version of a record might be used. Thus, using
     this isolation level, such reads are not consistent. This is also
     called a `dirty read.' Otherwise, this isolation level works like
     `READ COMMITTED'.

   * `READ COMMITTED'

     A somewhat Oracle-like isolation level. All `SELECT ... FOR
     UPDATE' and `SELECT ... LOCK IN SHARE MODE' statements lock only
     the index records, not the gaps before them, and thus allow the
     free insertion of new records next to locked records. `UPDATE' and
     `DELETE' statements using a unique index with a unique search
     condition lock only the index record found, not the gap before it.
     In range-type `UPDATE' and `DELETE' statements, `InnoDB' must set
     next-key or gap locks and block insertions by other users to the
     gaps covered by the range. This is necessary because `phantom rows'
     must be blocked for MySQL replication and recovery to work.

     Consistent reads behave as in Oracle: Each consistent read, even
     within the same transaction, sets and reads its own fresh
     snapshot. See *Note innodb-consistent-read::.

     *Note*:

     As of MySQL 5.1, if you use `READ COMMITTED' (which is equivalent
     to `innodb_locks_unsafe_for_binlog' in 5.0), you _must_ use
     row-based binary logging.

   * `REPEATABLE READ'

     This is the default isolation level of `InnoDB'. `SELECT ... FOR
     UPDATE', `SELECT ... LOCK IN SHARE MODE', `UPDATE', and `DELETE'
     statements that use a unique index with a unique search condition
     lock only the index record found, not the gap before it. With
     other search conditions, these operations employ next-key locking,
     locking the index range scanned with next-key or gap locks, and
     block new insertions by other users.

     In consistent reads, there is an important difference from the
     `READ COMMITTED' isolation level: All consistent reads within the
     same transaction read the same snapshot established by the first
     read. This convention means that if you issue several plain
     `SELECT' statements within the same transaction, these `SELECT'
     statements are consistent also with respect to each other. See
     *Note innodb-consistent-read::.

   * `SERIALIZABLE'

     This level is like `REPEATABLE READ', but `InnoDB' implicitly
     converts all plain `SELECT' statements to `SELECT ...  LOCK IN
     SHARE MODE'.


File: manual.info,  Node: xa,  Prev: set-transaction,  Up: sql-syntax-transactions

12.4.7 XA Transactions
----------------------

* Menu:

* xa-statements::                XA Transaction SQL Syntax
* xa-states::                    XA Transaction States

Support for XA transactions is available for the `InnoDB' storage
engine. The MySQL XA implementation is based on the X/Open CAE document
`Distributed Transaction Processing: The XA Specification'. This
document is published by The Open Group and available at
`http://www.opengroup.org/public/pubs/catalog/c193.htm'.  Limitations
of the current XA implementation are described in *Note
xa-restrictions::.

On the client side, there are no special requirements. The XA interface
to a MySQL server consists of SQL statements that begin with the `XA'
keyword. MySQL client programs must be able to send SQL statements and
to understand the semantics of the XA statement interface. They do not
need be linked against a recent client library. Older client libraries
also will work.

Currently, among the MySQL Connectors, MySQL Connector/J 5.0.0 supports
XA directly (by means of a class interface that handles the XA SQL
statement interface for you).

XA supports distributed transactions; that is, the ability to allow
multiple separate transactional resources to participate in a global
transaction. Transactional resources often are RDBMSs but may be other
kinds of resources.

A global transaction involves several actions that are transactional in
themselves, but that all must either complete successfully as a group,
or all be rolled back as a group. In essence, this extends ACID
properties `up a level' so that multiple ACID transactions can be
executed in concert as components of a global operation that also has
ACID properties.  (However, for a distributed transaction, you must use
the `SERIALIZABLE' isolation level to achieve ACID properties. It is
enough to use `REPEATABLE READ' for a non-distributed transaction, but
not for a distributed transaction.)

Some examples of distributed transactions:

   * An application may act as an integration tool that combines a
     messaging service with an RDBMS. The application makes sure that
     transactions dealing with message sending, retrieval, and
     processing that also involve a transactional database all happen
     in a global transaction. You can think of this as `transactional
     email.'

   * An application performs actions that involve different database
     servers, such as a MySQL server and an Oracle server (or multiple
     MySQL servers), where actions that involve multiple servers must
     happen as part of a global transaction, rather than as separate
     transactions local to each server.

   * A bank keeps account information in an RDBMS and distributes and
     receives money via automated teller machines (ATMs). It is
     necessary to ensure that ATM actions are correctly reflected in
     the accounts, but this cannot be done with the RDBMS alone.  A
     global transaction manager integrates the ATM and database
     resources to ensure overall consistency of financial transactions.

Applications that use global transactions involve one or more Resource
Managers and a Transaction Manager:

   * A Resource Manager (RM) provides access to transactional
     resources. A database server is one kind of resource manager.  It
     must be possible to either commit or roll back transactions
     managed by the RM.

   * A Transaction Manager (TM) coordinates the transactions that are
     part of a global transaction. It communicates with the RMs that
     handle each of these transactions. The individual transactions
     within a global transaction are `branches' of the global
     transaction. Global transactions and their branches are identified
     by a naming scheme described later.

The MySQL implementation of XA MySQL enables a MySQL server to act as a
Resource Manager that handles XA transactions within a global
transaction. A client program that connects to the MySQL server acts as
the Transaction Manager.

To carry out a global transaction, it is necessary to know which
components are involved, and bring each component to a point when it
can be committed or rolled back. Depending on what each component
reports about its ability to succeed, they must all commit or roll back
as an atomic group. That is, either all components must commit, or all
components musts roll back. To manage a global transaction, it is
necessary to take into account that any component or the connecting
network might fail.

The process for executing a global transaction uses two-phase commit
(2PC). This takes place after the actions performed by the branches of
the global transaction have been executed.

  1. In the first phase, all branches are prepared. That is, they are
     told by the TM to get ready to commit. Typically, this means each
     RM that manages a branch records the actions for the branch in
     stable storage. The branches indicate whether they are able to do
     this, and these results are used for the second phase.

  2. In the second phase, the TM tells the RMs whether to commit or
     roll back. If all branches indicated when they were prepared that
     they will be able to commit, all branches are told to commit. If
     any branch indicated when it was prepared that it will not be able
     to commit, all branches are told to roll back.

In some cases, a global transaction might use one-phase commit (1PC).
For example, when a Transaction Manager finds that a global transaction
consists of only one transactional resource (that is, a single branch),
that resource can be told to prepare and commit at the same time.


File: manual.info,  Node: xa-statements,  Next: xa-states,  Prev: xa,  Up: xa

12.4.7.1 XA Transaction SQL Syntax
..................................

To perform XA transactions in MySQL, use the following statements:

     XA {START|BEGIN} XID [JOIN|RESUME]

     XA END XID [SUSPEND [FOR MIGRATE]]

     XA PREPARE XID

     XA COMMIT XID [ONE PHASE]

     XA ROLLBACK XID

     XA RECOVER

For `XA START', the `JOIN' and `RESUME' clauses are not supported.

For `XA END' the `SUSPEND [FOR MIGRATE]' clause is not supported.

Each XA statement begins with the `XA' keyword, and most of them
require an XID value. An XID is an XA transaction identifier. It
indicates which transaction the statement applies to. XID values are
supplied by the client, or generated by the MySQL server. An XID value
has from one to three parts:

     XID: GTRID [, BQUAL [, FORMATID ]]

GTRID is a global transaction identifier, BQUAL is a branch qualifier,
and FORMATID is a number that identifies the format used by the GTRID
and BQUAL values. As indicated by the syntax, BQUAL and FORMATID are
optional. The default BQUAL value is `''' if not given. The default
FORMATID value is 1 if not given.

GTRID and BQUAL must be string literals, each up to 64 bytes (not
characters) long.  GTRID and BQUAL can be specified in several ways.
You can use a quoted string (`'ab''), hex string (`0x6162', `X'ab''), or
bit value (`b'NNNN'').

FORMATID is an unsigned integer.

The GTRID and BQUAL values are interpreted in bytes by the MySQL
server's underlying XA support routines. However, while an SQL
statement containing an XA statement is being parsed, the server works
with some specific character set. To be safe, write GTRID and BQUAL as
hex strings.

XID values typically are generated by the Transaction Manager. Values
generated by one TM must be different from values generated by other
TMs. A given TM must be able to recognize its own XID values in a list
of values returned by the `XA RECOVER' statement.

MySQL Enterprise

For expert advice on XA Distributed Transaction Support subscribe to
the MySQL Enterprise Monitor. For more information, see `advisors.html'.

`XA START XID' starts an XA transaction with the given XID value. Each
XA transaction must have a unique XID value, so the value must not
currently be used by another XA transaction. Uniqueness is assessed
using the GTRID and BQUAL values. All following XA statements for the
XA transaction must be specified using the same XID value as that given
in the `XA START' statement. If you use any of those statements but
specify an XID value that does not correspond to some existing XA
transaction, an error occurs.

One or more XA transactions can be part of the same global transaction.
All XA transactions within a given global transaction must use the same
GTRID value in the XID value. For this reason, GTRID values must be
globally unique so that there is no ambiguity about which global
transaction a given XA transaction is part of. The BQUAL part of the
XID value must be different for each XA transaction within a global
transaction. (The requirement that BQUAL values be different is a
limitation of the current MySQL XA implementation. It is not part of
the XA specification.)

The `XA RECOVER' statement returns information for those XA
transactions on the MySQL server that are in the `PREPARED' state. (See
*Note xa-states::.) The output includes a row for each such XA
transaction on the server, regardless of which client started it.

`XA RECOVER' output rows look like this (for an example XID value
consisting of the parts `'abc'', `'def'', and `7'):

     mysql> XA RECOVER;
     +----------+--------------+--------------+--------+
     | formatID | gtrid_length | bqual_length | data   |
     +----------+--------------+--------------+--------+
     |        7 |            3 |            3 | abcdef |
     +----------+--------------+--------------+--------+

The output columns have the following meanings:

   * `formatID' is the FORMATID part of the transaction XID

   * `gtrid_length' is the length in bytes of the GTRID part of the XID

   * `bqual_length' is the length in bytes of the BQUAL part of the XID

   * `data' is the concatenation of the GTRID and BQUAL parts of the XID


File: manual.info,  Node: xa-states,  Prev: xa-statements,  Up: xa

12.4.7.2 XA Transaction States
..............................

An XA transaction progresses through the following states:

  1. Use `XA START' to start an XA transaction and put it in the
     `ACTIVE' state.

  2. For an `ACTIVE' XA transaction, issue the SQL statements that make
     up the transaction, and then issue an `XA END' statement. `XA END'
     puts the transaction in the `IDLE' state.

  3. For an `IDLE' XA transaction, you can issue either an `XA PREPARE'
     statement or an `XA COMMIT ... ONE PHASE' statement:

        * `XA PREPARE' puts the transaction in the `PREPARED' state. An
          `XA RECOVER' statement at this point will include the
          transaction's XID value in its output, because `XA RECOVER'
          lists all XA transactions that are in the `PREPARED' state.

        * `XA COMMIT ... ONE PHASE' prepares and commits the
          transaction. The XID value will not be listed by `XA RECOVER'
          because the transaction terminates.

  4. For a `PREPARED' XA transaction, you can issue an `XA COMMIT'
     statement to commit and terminate the transaction, or `XA
     ROLLBACK' to roll back and terminate the transaction.

Here is a simple XA transaction that inserts a row into a table as part
of a global transaction:

     mysql> XA START 'xatest';
     Query OK, 0 rows affected (0.00 sec)

     mysql> INSERT INTO mytable (i) VALUES(10);
     Query OK, 1 row affected (0.04 sec)

     mysql> XA END 'xatest';
     Query OK, 0 rows affected (0.00 sec)

     mysql> XA PREPARE 'xatest';
     Query OK, 0 rows affected (0.00 sec)

     mysql> XA COMMIT 'xatest';
     Query OK, 0 rows affected (0.00 sec)

Within the context of a given client connection, XA transactions and
local (non-XA) transactions are mutually exclusive. For example, if `XA
START' has been issued to begin an XA transaction, a local transaction
cannot be started until the XA transaction has been committed or rolled
back.  Conversely, if a local transaction has been started with `START
TRANSACTION', no XA statements can be used until the transaction has
been committed or rolled back.

Note that if an XA transaction is in the `ACTIVE' state, you cannot
issue any statements that cause an implicit commit. That would violate
the XA contract because you could not roll back the XA transaction. You
will receive the following error if you try to execute such a statement:

     ERROR 1399 (XAE07): XAER_RMFAIL: The command cannot be executed
     when global transaction is in the ACTIVE state

Statements to which the preceding remark applies are listed at *Note
implicit-commit::.


File: manual.info,  Node: sql-syntax-server-administration,  Next: sql-syntax-replication,  Prev: sql-syntax-transactions,  Up: sql-syntax

12.5 Database Administration Statements
=======================================

* Menu:

* account-management-sql::       Account Management Statements
* table-maintenance-sql::        Table Maintenance Statements
* plugin-sql::                   Plugin and User-Defined Function Statements
* set-option::                   `SET' Syntax
* show::                         `SHOW' Syntax
* other-administrative-sql::     Other Administrative Statements


File: manual.info,  Node: account-management-sql,  Next: table-maintenance-sql,  Prev: sql-syntax-server-administration,  Up: sql-syntax-server-administration

12.5.1 Account Management Statements
------------------------------------

* Menu:

* create-user::                  `CREATE USER' Syntax
* drop-user::                    `DROP USER' Syntax
* grant::                        `GRANT' Syntax
* rename-user::                  `RENAME USER' Syntax
* revoke::                       `REVOKE' Syntax
* set-password::                 `SET PASSWORD' Syntax

MySQL account information is stored in the tables of the `mysql'
database. This database and the access control system are discussed
extensively in *Note server-administration::, which you should consult
for additional details.

*Important*:

Some releases of MySQL introduce changes to the structure of the grant
tables to add new privileges or features. Whenever you update to a new
version of MySQL, you should update your grant tables to make sure that
they have the current structure so that you can take advantage of any
new capabilities. See *Note mysql-upgrade::.

MySQL Enterprise

In a production environment it is always prudent to examine any changes
to users' accounts. The MySQL Enterprise Monitor provides notification
whenever users' privileges are altered.  For more information, see
`advisors.html'.


File: manual.info,  Node: create-user,  Next: drop-user,  Prev: account-management-sql,  Up: account-management-sql

12.5.1.1 `CREATE USER' Syntax
.............................

     CREATE USER USER [IDENTIFIED BY [PASSWORD] 'PASSWORD']
         [, USER [IDENTIFIED BY [PASSWORD] 'PASSWORD']] ...

The `CREATE USER' statement creates new MySQL accounts. To use it, you
must have the global `CREATE USER' privilege or the `INSERT' privilege
for the `mysql' database. For each account, `CREATE USER' creates a new
row in the `mysql.user' table that has no privileges. An error occurs
if the account already exists. Each account is named using the same
format as for the `GRANT' statement; for example,
`'jeffrey'@'localhost''. If you specify only the username part of the
account name, a hostname part of `'%'' is used. For additional
information about specifying account names, see *Note grant::.

The account can be given a password with the optional `IDENTIFIED BY'
clause. The USER value and the password are given the same way as for
the `GRANT' statement. In particular, to specify the password in plain
text, omit the `PASSWORD' keyword. To specify the password as the
hashed value as returned by the `PASSWORD()' function, include the
`PASSWORD' keyword. See *Note grant::.

*Important*:

This statement may be recorded in a history file such as
`~/.mysql_history', which means that plaintext passwords may be read by
anyone having read access to such files.


File: manual.info,  Node: drop-user,  Next: grant,  Prev: create-user,  Up: account-management-sql

12.5.1.2 `DROP USER' Syntax
...........................

     DROP USER USER [, USER] ...

The `DROP USER' statement removes one or more MySQL accounts. It
removes privilege rows for the account from all grant tables. To use
this statement, you must have the global `CREATE USER' privilege or the
`DELETE' privilege for the `mysql' database. Each account is named using
the same format as for the `GRANT' statement; for example,
`'jeffrey'@'localhost''. If you specify only the username part of the
account name, a hostname part of `'%'' is used. For additional
information about specifying account names, see *Note grant::.

With `DROP USER', you can remove an account and its privileges as
follows:

     DROP USER USER;

*Important*:

`DROP USER' does not automatically close any open user sessions.
Rather, in the event that a user with an open session is dropped, the
statement does not take effect until that user's session is closed.
Once the session is closed, the user is dropped, and that user's next
attempt to log in will fail. _This is by design_.

`DROP USER' does not automatically delete or invalidate any database
objects that the user created. This applies to tables, views, stored
routines, triggers, and events.


File: manual.info,  Node: grant,  Next: rename-user,  Prev: drop-user,  Up: account-management-sql

12.5.1.3 `GRANT' Syntax
.......................

     GRANT
         PRIV_TYPE [(COLUMN_LIST)]
           [, PRIV_TYPE [(COLUMN_LIST)]] ...
         ON [OBJECT_TYPE]
             {
                 *
               | *.*
               | DB_NAME.*
               | DB_NAME.TBL_NAME
               | TBL_NAME
               | DB_NAME.ROUTINE_NAME

             }
         TO USER [IDENTIFIED BY [PASSWORD] 'PASSWORD']
             [, USER [IDENTIFIED BY [PASSWORD] 'PASSWORD']] ...
         [REQUIRE
             NONE |
             [{SSL| X509}]
             [CIPHER 'CIPHER' [AND]]
             [ISSUER 'ISSUER' [AND]]
             [SUBJECT 'SUBJECT']]
         [WITH WITH_OPTION [WITH_OPTION] ...]

     OBJECT_TYPE =
         TABLE
       | FUNCTION
       | PROCEDURE

     WITH_OPTION =
         GRANT OPTION
       | MAX_QUERIES_PER_HOUR COUNT
       | MAX_UPDATES_PER_HOUR COUNT
       | MAX_CONNECTIONS_PER_HOUR COUNT
       | MAX_USER_CONNECTIONS COUNT

The `GRANT' statement enables system administrators to create MySQL
user accounts and to grant rights to accounts. To use `GRANT', you must
have the `GRANT OPTION' privilege, and you must have the privileges
that you are granting. The `REVOKE' statement is related and enables
administrators to remove account privileges. See *Note revoke::.

MySQL Enterprise

For automated notification of users with inappropriate privileges,
subscribe to the MySQL Enterprise Monitor. For more information, see
`advisors.html'.

MySQL account information is stored in the tables of the `mysql'
database. This database and the access control system are discussed
extensively in *Note server-administration::, which you should consult
for additional details.

*Important*:

Some releases of MySQL introduce changes to the structure of the grant
tables to add new privileges or features. Whenever you update to a new
version of MySQL, you should update your grant tables to make sure that
they have the current structure so that you can take advantage of any
new capabilities. See *Note mysql-upgrade::.

If the grant tables hold privilege rows that contain mixed-case
database or table names and the `lower_case_table_names' system
variable is set to a non-zero value, `REVOKE' cannot be used to revoke
these privileges. It will be necessary to manipulate the grant tables
directly. (`GRANT' will not create such rows when
`lower_case_table_names' is set, but such rows might have been created
prior to setting the variable.)

Privileges can be granted at several levels. The examples shown here
include no `IDENTIFIED BY 'PASSWORD'' clause for brevity, but you
should include one if the account does not already exist to avoid
creating an account with no password.

   * *Global level*

     Global privileges apply to all databases on a given server.  These
     privileges are stored in the `mysql.user' table. `GRANT ALL ON
     *.*' and `REVOKE ALL ON *.*' grant and revoke only global
     privileges.

          GRANT ALL ON *.* TO 'someuser'@'somehost';
          GRANT SELECT, INSERT ON *.* TO 'someuser'@'somehost';

   * *Database level*

     Database privileges apply to all objects in a given database.
     These privileges are stored in the `mysql.db' and `mysql.host'
     tables. `GRANT ALL ON DB_NAME.*' and `REVOKE ALL ON DB_NAME.*'
     grant and revoke only database privileges.

          GRANT ALL ON mydb.* TO 'someuser'@'somehost';
          GRANT SELECT, INSERT ON mydb.* TO 'someuser'@'somehost';

   * *Table level*

     Table privileges apply to all columns in a given table.  These
     privileges are stored in the `mysql.tables_priv' table. `GRANT ALL
     ON DB_NAME.TBL_NAME' and `REVOKE ALL ON DB_NAME.TBL_NAME' grant
     and revoke only table privileges.

          GRANT ALL ON mydb.mytbl TO 'someuser'@'somehost';
          GRANT SELECT, INSERT ON mydb.mytbl TO 'someuser'@'somehost';

     If you specify TBL_NAME rather than `db_name.tbl_name', the
     statement applies to TBL_NAME in the default database.

   * *Column level*

     Column privileges apply to single columns in a given table.  These
     privileges are stored in the `mysql.columns_priv' table. When using
     `REVOKE', you must specify the same columns that were granted. The
     column or columns for which the privileges are to be granted must
     be enclosed within parentheses.

          GRANT SELECT (col1), INSERT (col1,col2) ON mydb.mytbl TO 'someuser'@'somehost';

   * *Routine level*

     The `CREATE ROUTINE', `ALTER ROUTINE', `EXECUTE', and `GRANT'
     privileges apply to stored routines (functions and procedures).
     They can be granted at the global and database levels. Also,
     except for `CREATE ROUTINE', these privileges can be granted at the
     routine level for individual routines and are stored in the
     `mysql.procs_priv' table.

          GRANT CREATE ROUTINE ON mydb.* TO 'someuser'@'somehost';
          GRANT EXECUTE ON PROCEDURE mydb.myproc TO 'someuser'@'somehost';

The OBJECT_TYPE clause should be specified as `TABLE', `FUNCTION', or
`PROCEDURE' when the following object is a table, a stored function, or
a stored procedure.

*Warning*:

If you specify `ON *' and you have _not_ selected a default database,
the privileges granted are global.

For the `GRANT' and `REVOKE' statements, PRIV_TYPE can be specified as
any of the following:

*Privilege*            *Meaning*
`ALL [PRIVILEGES]'     Grants all privileges at specified access level
                       except `GRANT OPTION'
`ALTER'                Enables use of `ALTER TABLE'
`ALTER ROUTINE'        Enables stored routines to be altered or dropped
`CREATE'               Enables use of `CREATE TABLE'
`CREATE ROUTINE'       Enables creation of stored routines
`CREATE TEMPORARY      Enables use of `CREATE TEMPORARY TABLE'
TABLES'                
`CREATE USER'          Enables use of `CREATE USER', `DROP USER',
                       `RENAME USER', and `REVOKE ALL PRIVILEGES'.
`CREATE VIEW'          Enables use of `CREATE VIEW'
`DELETE'               Enables use of `DELETE'
`DROP'                 Enables use of `DROP TABLE'
`EVENT'                Enables creation of events for the event scheduler
`EXECUTE'              Enables the user to run stored routines
`FILE'                 Enables use of `SELECT ... INTO OUTFILE' and
                       `LOAD DATA INFILE'
`INDEX'                Enables use of `CREATE INDEX' and `DROP INDEX'
`INSERT'               Enables use of `INSERT'
`LOCK TABLES'          Enables use of `LOCK TABLES' on tables for which
                       you have the `SELECT' privilege
`PROCESS'              Enables the user to see all processes with `SHOW
                       PROCESSLIST'
`REFERENCES'           Not implemented
`RELOAD'               Enables use of `FLUSH'
`REPLICATION CLIENT'   Enables the user to ask where slave or master
                       servers are
`REPLICATION SLAVE'    Needed for replication slaves (to read binary log
                       events from the master)
`SELECT'               Enables use of `SELECT'
`SHOW DATABASES'       `SHOW DATABASES' shows all databases
`SHOW VIEW'            Enables use of `SHOW CREATE VIEW'
`SHUTDOWN'             Enables use of `mysqladmin shutdown'
`SUPER'                Enables use of `CHANGE MASTER', `KILL', `PURGE
                       MASTER LOGS', and `SET GLOBAL' statements, the
                       `mysqladmin debug' command; allows you to connect
                       (once) even if `max_connections' is reached
`TRIGGER'              Enables the user to create or drop triggers
`UPDATE'               Enables use of `UPDATE'
`USAGE'                Synonym for `no privileges'
`GRANT OPTION'         Enables privileges to be granted

The `EVENT' and `TRIGGER' privileges were added in MySQL 5.1.6. A
trigger is associated with a table, so to create or drop a trigger, you
must have the `TRIGGER' privilege for the table, not the trigger.
(Before MySQL 5.1.6, the `SUPER' privilege was required to create or
drop triggers.)

The `REFERENCES' privilege currently is unused.

`USAGE' can be specified when you want to create a user that has no
privileges.

Use `SHOW GRANTS' to determine what privileges an account has. See
*Note show-grants::.

You can assign global privileges by using `ON *.*' syntax or
database-level privileges by using `ON DB_NAME.*' syntax. If you
specify `ON *' and you have selected a default database, the privileges
are granted in that database.

The `FILE', `PROCESS', `RELOAD', `REPLICATION CLIENT', `REPLICATION
SLAVE', `SHOW DATABASES', `SHUTDOWN', `SUPER', and `CREATE USER'
privileges are administrative privileges that can only be granted
globally (using `ON *.*' syntax).

Other privileges can be granted globally or at more specific levels.

The PRIV_TYPE values that you can specify for a table are `SELECT',
`INSERT', `UPDATE', `DELETE', `CREATE', `DROP', `GRANT OPTION',
`INDEX', `ALTER', `CREATE VIEW', `SHOW VIEW' and `TRIGGER'.

The PRIV_TYPE values that you can specify for a column (that is, when
you use a COLUMN_LIST clause) are `SELECT', `INSERT', and `UPDATE'.

The PRIV_TYPE values that you can specify at the routine level are
`ALTER ROUTINE', `EXECUTE', and `GRANT OPTION'. `CREATE ROUTINE' is not
a routine-level privilege because you must have this privilege to
create a routine in the first place.

For the global, database, table, and routine levels, `GRANT ALL'
assigns only the privileges that exist at the level you are granting.
For example, `GRANT ALL ON DB_NAME.*' is a database-level statement, so
it does not grant any global-only privileges such as `FILE'.

MySQL allows you to grant privileges even on database objects that do
not exist. In such cases, the privileges to be granted must include the
`CREATE' privilege.  _This behavior is by design_, and is intended to
enable the database administrator to prepare user accounts and
privileges for database objects that are to be created at a later time.

*Important*:

_MySQL does not automatically revoke any privileges when you drop a
table or database_. However, if you drop a routine, any routine-level
privileges granted for that routine are revoked.

*Note*:

The ``_'' and ``%'' wildcards are allowed when specifying database
names in `GRANT' statements that grant privileges at the global or
database levels. This means, for example, that if you want to use a
``_'' character as part of a database name, you should specify it as
``\_'' in the `GRANT' statement, to prevent the user from being able to
access additional databases matching the wildcard pattern; for example,
`GRANT ... ON `foo\_bar`.* TO ...'.

To accommodate granting rights to users from arbitrary hosts, MySQL
supports specifying the USER value in the form `USER_NAME@HOST_NAME'.
If a USER_NAME or HOST_NAME value is legal as an unquoted identifier,
you need not quote it. However, quotes are necessary to specify a
USER_NAME string containing special characters (such as ``-''), or a
HOST_NAME string containing special characters or wildcard characters
(such as ``%''); for example, `'test-user'@'test-hostname''. Quote the
username and hostname separately.

You can specify wildcards in the hostname. For example,
`USER_NAME@'%.loc.gov'' applies to USER_NAME for any host in the
`loc.gov' domain, and `USER_NAME@'144.155.166.%'' applies to USER_NAME
for any host in the `144.155.166' class C subnet.

The simple form USER_NAME is a synonym for `USER_NAME@'%''.

_MySQL does not support wildcards in usernames_. Anonymous users are
defined by inserting entries with `User=''' into the `mysql.user' table
or by creating a user with an empty name with the `GRANT' statement:

     GRANT ALL ON test.* TO ''@'localhost' ...

When specifying quoted values, quote database, table, column, and
routine names as identifiers, using backticks (```''). Quote hostnames,
usernames, and passwords as strings, using single quotes (``''').

*Warning*:

If you allow anonymous users to connect to the MySQL server, you should
also grant privileges to all local users as `USER_NAME@localhost'.
Otherwise, the anonymous user account for `localhost' in the
`mysql.user' table (created during MySQL installation) is used when
named users try to log in to the MySQL server from the local machine.
For details, see *Note connection-access::.

You can determine whether this applies to you by executing the
following query, which lists any anonymous users:

     SELECT Host, User FROM mysql.user WHERE User='';

If you want to delete the local anonymous user account to avoid the
problem just described, use these statements:

     DELETE FROM mysql.user WHERE Host='localhost' AND User='';
     FLUSH PRIVILEGES;

`GRANT' supports hostnames up to 60 characters long. Database, table,
column, and routine names can be up to 64 characters. Usernames can be
up to 16 characters.

*Note*:

_The allowable length for usernames cannot be changed by altering the
`mysql.user' table, and attempting to do so results in unpredictable
behavior which may even make it impossible for users to log in to the
MySQL server_. You should never alter any of the tables in the `mysql'
database in any manner whatsoever except by means of the procedure
prescribed by MySQL AB that is described in *Note mysql-upgrade::.

The privileges for a table, column, or routine are formed additively as
the logical `OR' of the privileges at each of the privilege levels. For
example, if the `mysql.user' table specifies that a user has a global
`SELECT' privilege, the privilege cannot be denied by an entry at the
database, table, or column level.

The privileges for a column can be calculated as follows:

     global privileges
     OR (database privileges AND host privileges)
     OR table privileges
     OR column privileges
     OR routine privileges

In most cases, you grant rights to a user at only one of the privilege
levels, so life is not normally this complicated. The details of the
privilege-checking procedure are presented in *Note privilege-system::.

If you grant privileges for a username/hostname combination that does
not exist in the `mysql.user' table, an entry is added and remains
there until deleted with a `DELETE' statement. In other words, `GRANT'
may create `user' table entries, but `REVOKE' does not remove them; you
must do that explicitly using `DROP USER' or `DELETE'.

If the account does not already exist, `GRANT' creates it. In the case
that you create a new account or if you have global grant privileges,
the account's password is set to the password specified by the
`IDENTIFIED BY' clause, if one is given. If the account already had a
password, it is replaced by the new one.

*Warning*:

If you create a new user but do not specify an `IDENTIFIED BY' clause,
the user has no password. This is very insecure. However, you can
enable the `NO_AUTO_CREATE_USER' SQL mode to prevent `GRANT' from
creating a new user if it would otherwise do so, unless `IDENTIFIED BY'
is given to provide the new user a non-empty password.

MySQL Enterprise

The MySQL Enterprise Monitor specifically guards against user accounts
with no passwords. To find out more, see `advisors.html'.

Passwords can also be set with the `SET PASSWORD' statement. See *Note
set-password::.

In the `IDENTIFIED BY' clause, the password should be given as the
literal password value. It is unnecessary to use the `PASSWORD()'
function as it is for the `SET PASSWORD' statement. For example:

     GRANT ... IDENTIFIED BY 'mypass';

If you do not want to send the password in clear text and you know the
hashed value that `PASSWORD()' would return for the password, you can
specify the hashed value preceded by the keyword `PASSWORD':

     GRANT ...
     IDENTIFIED BY PASSWORD '*6C8989366EAF75BB670AD8EA7A7FC1176A95CEF4';

In a C program, you can get the hashed value by using the
`make_scrambled_password()' C API function.

If you grant privileges for a database, an entry in the `mysql.db'
table is created if needed. If all privileges for the database are
removed with `REVOKE', this entry is deleted.

The `SHOW DATABASES' privilege enables the account to see database
names by issuing the `SHOW DATABASE' statement. Accounts that do not
have this privilege see only databases for which they have some
privileges, and cannot use the statement at all if the server was
started with the `--skip-show-database' option.

MySQL Enterprise

The `SHOW DATABASES' privilege should be granted only to users who need
to see all the databases on a MySQL server. Subscribers to the MySQL
Enterprise Monitor are alerted when servers are started without the
`--skip-show-database' option. For more information, see
`advisors.html'.

If a user has no privileges for a table, the table name is not
displayed when the user requests a list of tables (for example, with a
`SHOW TABLES' statement).

The `WITH GRANT OPTION' clause gives the user the ability to give to
other users any privileges the user has at the specified privilege
level. You should be careful to whom you give the `GRANT OPTION'
privilege, because two users with different privileges may be able to
join privileges!

You cannot grant another user a privilege which you yourself do not
have; the `GRANT OPTION' privilege enables you to assign only those
privileges which you yourself possess.

Be aware that when you grant a user the `GRANT OPTION' privilege at a
particular privilege level, any privileges the user possesses (or may
be given in the future) at that level can also be granted by that user
to other users.  Suppose that you grant a user the `INSERT' privilege
on a database. If you then grant the `SELECT' privilege on the database
and specify `WITH GRANT OPTION', that user can give to other users not
only the `SELECT' privilege, but also `INSERT'. If you then grant the
`UPDATE' privilege to the user on the database, the user can grant
`INSERT', `SELECT', and `UPDATE'.

For a non-administrative user, you should not grant the `ALTER'
privilege globally or for the `mysql' database. If you do that, the
user can try to subvert the privilege system by renaming tables!

The `MAX_QUERIES_PER_HOUR COUNT', `MAX_UPDATES_PER_HOUR COUNT', and
`MAX_CONNECTIONS_PER_HOUR COUNT' options limit the number of queries,
updates, and logins a user can perform during any given one-hour
period. (Queries for which results are served from the query cache do
not count against the `MAX_QUERIES_PER_HOUR' limit.) If COUNT is `0'
(the default), this means that there is no limitation for that user.

The `MAX_USER_CONNECTIONS COUNT' option limits the maximum number of
simultaneous connections that the account can make. If COUNT is `0'
(the default), the `max_user_connections' system variable determines
the number of simultaneous connections for the account.

Note: To specify any of these resource-limit options for an existing
user without affecting existing privileges, use `GRANT USAGE ON *.* ...
WITH MAX_...'.

See *Note user-resources::.

MySQL can check X509 certificate attributes in addition to the usual
authentication that is based on the username and password.  To specify
SSL-related options for a MySQL account, use the `REQUIRE' clause of the
`GRANT' statement. (For background information on the use of SSL with
MySQL, see *Note secure-connections::.)

There are a number of different possibilities for limiting connection
types for a given account:

   * `REQUIRE NONE' indicates that the account has no SSL or X509
     requirements. This is the default if no SSL-related `REQUIRE'
     options are specified. Unencrypted connections are allowed if the
     username and password are valid. However, encrypted connections
     can also be used, at the client's option, if the client has the
     proper certificate and key files. That is, the client need not
     specify any SSL command options, in which case the connection will
     be unencrypted. To use an encrypted connection, the client must
     specify either the `--ssl-ca' option, or all three of the
     `--ssl-ca', `--ssl-key', and `--ssl-cert' options.

   * The `REQUIRE SSL' option tells the server to allow only
     SSL-encrypted connections for the account.

          GRANT ALL PRIVILEGES ON test.* TO 'root'@'localhost'
            IDENTIFIED BY 'goodsecret' REQUIRE SSL;

     To connect, the client must specify the `--ssl-ca' option, and may
     additionally specify the `--ssl-key' and `--ssl-cert' options.

   * `REQUIRE X509' means that the client must have a valid certificate
     but that the exact certificate, issuer, and subject do not matter.
     The only requirement is that it should be possible to verify its
     signature with one of the CA certificates.

          GRANT ALL PRIVILEGES ON test.* TO 'root'@'localhost'
            IDENTIFIED BY 'goodsecret' REQUIRE X509;

     To connect, the client must specify the `--ssl-ca', `--ssl-key',
     and `--ssl-cert' options. This is also true for `ISSUER' and
     `SUBJECT' because those `REQUIRE' options imply `X509'.

   * `REQUIRE ISSUER 'ISSUER'' places the restriction on connection
     attempts that the client must present a valid X509 certificate
     issued by CA `'ISSUER''. If the client presents a certificate that
     is valid but has a different issuer, the server rejects the
     connection. Use of X509 certificates always implies encryption, so
     the `SSL' option is unnecessary in this case.

          GRANT ALL PRIVILEGES ON test.* TO 'root'@'localhost'
            IDENTIFIED BY 'goodsecret'
            REQUIRE ISSUER '/C=FI/ST=Some-State/L=Helsinki/
              O=MySQL Finland AB/CN=Tonu Samuel/Email=tonu@example.com';

     Note that the `'ISSUER'' value should be entered as a single
     string.

   * `REQUIRE SUBJECT 'SUBJECT'' places the restriction on connection
     attempts that the client must present a valid X509 certificate
     containing the subject SUBJECT. If the client presents a
     certificate that is valid but has a different subject, the server
     rejects the connection.

          GRANT ALL PRIVILEGES ON test.* TO 'root'@'localhost'
            IDENTIFIED BY 'goodsecret'
            REQUIRE SUBJECT '/C=EE/ST=Some-State/L=Tallinn/
              O=MySQL demo client certificate/
              CN=Tonu Samuel/Email=tonu@example.com';

     Note that the `'SUBJECT'' value should be entered as a single
     string.

   * `REQUIRE CIPHER 'CIPHER'' is needed to ensure that ciphers and key
     lengths of sufficient strength are used. SSL itself can be weak if
     old algorithms using short encryption keys are used. Using this
     option, you can ask that a specific cipher method is used to allow
     a connection.

          GRANT ALL PRIVILEGES ON test.* TO 'root'@'localhost'
            IDENTIFIED BY 'goodsecret'
            REQUIRE CIPHER 'EDH-RSA-DES-CBC3-SHA';

The `SUBJECT', `ISSUER', and `CIPHER' options can be combined in the
`REQUIRE' clause like this:

     GRANT ALL PRIVILEGES ON test.* TO 'root'@'localhost'
       IDENTIFIED BY 'goodsecret'
       REQUIRE SUBJECT '/C=EE/ST=Some-State/L=Tallinn/
         O=MySQL demo client certificate/
         CN=Tonu Samuel/Email=tonu@example.com'
       AND ISSUER '/C=FI/ST=Some-State/L=Helsinki/
         O=MySQL Finland AB/CN=Tonu Samuel/Email=tonu@example.com'
       AND CIPHER 'EDH-RSA-DES-CBC3-SHA';

The `AND' keyword is optional between `REQUIRE' options.

The order of the options does not matter, but no option can be
specified twice.

When `mysqld' starts, all privileges are read into memory. For details,
see *Note privilege-changes::.

Note that if you are using table, column, or routine privileges for
even one user, the server examines table, column, and routine
privileges for all users and this slows down MySQL a bit. Similarly, if
you limit the number of queries, updates, or connections for any users,
the server must monitor these values.

The biggest differences between the standard SQL and MySQL versions of
`GRANT' are:

   * In MySQL, privileges are associated with the combination of a
     hostname and username and not with only a username.

   * Standard SQL does not have global or database-level privileges,
     nor does it support all the privilege types that MySQL supports.

   * MySQL does not support the standard SQL `UNDER' privilege.

   * Standard SQL privileges are structured in a hierarchical manner.
     If you remove a user, all privileges the user has been granted are
     revoked. This is also true in MySQL if you use `DROP USER'. See
     *Note drop-user::.

   * In standard SQL, when you drop a table, all privileges for the
     table are revoked. In standard SQL, when you revoke a privilege,
     all privileges that were granted based on that privilege are also
     revoked. In MySQL, privileges can be dropped only with explicit
     `REVOKE' statements or by manipulating values stored in the MySQL
     grant tables.

   * In MySQL, it is possible to have the `INSERT' privilege for only
     some of the columns in a table. In this case, you can still execute
     `INSERT' statements on the table, provided that you omit those
     columns for which you do not have the `INSERT' privilege. The
     omitted columns are set to their implicit default values if strict
     SQL mode is not enabled. In strict mode, the statement is rejected
     if any of the omitted columns have no default value. (Standard SQL
     requires you to have the `INSERT' privilege on all columns.)
     *Note server-sql-mode::, discusses strict mode.  *Note
     data-type-defaults::, discusses implicit default values.


File: manual.info,  Node: rename-user,  Next: revoke,  Prev: grant,  Up: account-management-sql

12.5.1.4 `RENAME USER' Syntax
.............................

     RENAME USER OLD_USER TO NEW_USER
         [, OLD_USER TO NEW_USER] ...

The `RENAME USER' statement renames existing MySQL accounts. To use it,
you must have the global `CREATE USER' privilege or the `UPDATE'
privilege for the `mysql' database. An error occurs if any old account
does not exist or any new account exists. Each account is named using
the same format as for the `GRANT' statement; for example,
`'jeffrey'@'localhost''. If you specify only the username part of the
account name, a hostname part of `'%'' is used. For additional
information about specifying account names, see *Note grant::.

`RENAME USER' does not automatically migrate any database objects that
the user created, nor does it migrate any privileges that the user had
prior to the renaming. This applies to tables, views, stored routines,
triggers, and events.


File: manual.info,  Node: revoke,  Next: set-password,  Prev: rename-user,  Up: account-management-sql

12.5.1.5 `REVOKE' Syntax
........................

     REVOKE
         PRIV_TYPE [(COLUMN_LIST)]
           [, PRIV_TYPE [(COLUMN_LIST)]] ...
         ON [OBJECT_TYPE]
             {
                 *
               | *.*
               | DB_NAME.*
               | DB_NAME.TBL_NAME
               | TBL_NAME
               | DB_NAME.ROUTINE_NAME

             }
         FROM USER [, USER] ...

     REVOKE ALL PRIVILEGES, GRANT OPTION FROM USER [, USER] ...

The `REVOKE' statement enables system administrators to revoke
privileges from MySQL accounts. Each account is named using the same
format as for the `GRANT' statement; for example,
`'jeffrey'@'localhost''. If you specify only the username part of the
account name, a hostname part of `'%'' is used. For additional
information about specifying account names, see *Note grant::.

To use the first `REVOKE' syntax, you must have the `GRANT OPTION'
privilege, and you must have the privileges that you are revoking.

For details on the levels at which privileges exist, the allowable
PRIV_TYPE values, and the syntax for specifying users and passwords, see
*Note grant::

If the grant tables hold privilege rows that contain mixed-case
database or table names and the `lower_case_table_names' system
variable is set to a non-zero value, `REVOKE' cannot be used to revoke
these privileges. It will be necessary to manipulate the grant tables
directly. (`GRANT' will not create such rows when
`lower_case_table_names' is set, but such rows might have been created
prior to setting the variable.)

To revoke all privileges, use the following syntax, which drops all
global, database-, table-, column-, and routine-level privileges for
the named user or users:

     REVOKE ALL PRIVILEGES, GRANT OPTION FROM USER [, USER] ...

To use this `REVOKE' syntax, you must have the global `CREATE USER'
privilege or the `UPDATE' privilege for the `mysql' database.

`REVOKE' removes privileges, but does not drop `user' table entries.
You must do that explicitly using `DELETE' or `DROP USER' (see *Note
drop-user::).


File: manual.info,  Node: set-password,  Prev: revoke,  Up: account-management-sql

12.5.1.6 `SET PASSWORD' Syntax
..............................

     SET PASSWORD [FOR USER] =
         {
             PASSWORD('SOME PASSWORD')
           | OLD_PASSWORD('SOME PASSWORD')
           | 'ENCRYPTED PASSWORD'
         }

The `SET PASSWORD' statement assigns a password to an existing MySQL
user account.

If the password is specified using the `PASSWORD()' or `OLD_PASSWORD()'
function, the literal text of the password should be given. If the
password is specified without using either function, the password
should be the already-encrypted password value as returned by
`PASSWORD()'.

With no `FOR' clause, this statement sets the password for the current
user. Any client that has connected to the server using a non-anonymous
account can change the password for that account.

With a `FOR' clause, this statement sets the password for a specific
account on the current server host. Only clients that have the `UPDATE'
privilege for the `mysql' database can do this. The USER value should
be given in `USER_NAME@HOST_NAME' format, where USER_NAME and HOST_NAME
are exactly as they are listed in the `User' and `Host' columns of the
`mysql.user' table entry. For example, if you had an entry with `User'
and `Host' column values of `'bob'' and `'%.loc.gov'', you would write
the statement like this:

     SET PASSWORD FOR 'bob'@'%.loc.gov' = PASSWORD('NEWPASS');

That is equivalent to the following statements:

     UPDATE mysql.user SET Password=PASSWORD('NEWPASS')
       WHERE User='bob' AND Host='%.loc.gov';
     FLUSH PRIVILEGES;

*Note*:

If you are connecting to a MySQL 4.1 or later server using a pre-4.1
client program, do not use the preceding `SET PASSWORD' or `UPDATE'
statement without reading *Note password-hashing::, first. The password
format changed in MySQL 4.1, and under certain circumstances it is
possible that if you change your password, you might not be able to
connect to the server afterward.

You can see which account the server authenticated you as by executing
`SELECT CURRENT_USER()'.

MySQL Enterprise

For automated notification of users without passwords, subscribe to the
MySQL Enterprise Monitor. For more information see `advisors.html'.


File: manual.info,  Node: table-maintenance-sql,  Next: plugin-sql,  Prev: account-management-sql,  Up: sql-syntax-server-administration

12.5.2 Table Maintenance Statements
-----------------------------------

* Menu:

* analyze-table::                `ANALYZE TABLE' Syntax
* backup-table::                 `BACKUP TABLE' Syntax
* check-table::                  `CHECK TABLE' Syntax
* checksum-table::               `CHECKSUM TABLE' Syntax
* optimize-table::               `OPTIMIZE TABLE' Syntax
* repair-table::                 `REPAIR TABLE' Syntax
* restore-table::                `RESTORE TABLE' Syntax


File: manual.info,  Node: analyze-table,  Next: backup-table,  Prev: table-maintenance-sql,  Up: table-maintenance-sql

12.5.2.1 `ANALYZE TABLE' Syntax
...............................

     ANALYZE [LOCAL | NO_WRITE_TO_BINLOG] TABLE TBL_NAME [, TBL_NAME] ...

`ANALYZE TABLE' analyzes and stores the key distribution for a table.
During the analysis, the table is locked with a read lock for `MyISAM'.
For `InnoDB' the table is locked with a write lock.  This statement
works with `MyISAM', and `InnoDB' tables. For `MyISAM' tables, this
statement is equivalent to using `myisamchk --analyze'.

For more information on how the analysis works within`InnoDB', see
*Note innodb-restrictions::.

MySQL Enterprise

For expert advice on optimizing tables subscribe to the MySQL
Enterprise Monitor. For more information, see `advisors.html'.

MySQL uses the stored key distribution to decide the order in which
tables should be joined when you perform a join on something other than
a constant. In addition, key distributions can be used when deciding
which indexes to use for a specific table within a query.

This statement requires `SELECT' and `INSERT' privileges for the table.

`ANALYZE TABLE' is not supported for partitioned tables.

`ANALYZE TABLE' returns a result set with the following columns:

*Column*    *Value*
`Table'     The table name
`Op'        Always `analyze'
`Msg_type'  One of `status', `error', `info', or
            `warning'
`Msg_text'  The message

You can check the stored key distribution with the `SHOW INDEX'
statement. See *Note show-index::.

If the table has not changed since the last `ANALYZE TABLE' statement,
the table is not analyzed again.

By default, `ANALYZE TABLE' statements are written to the binary log so
that such statements used on a MySQL server acting as a replication
master will be replicated to replication slaves. Logging can be
suppressed with the optional `NO_WRITE_TO_BINLOG' keyword or its alias
`LOCAL'.


File: manual.info,  Node: backup-table,  Next: check-table,  Prev: analyze-table,  Up: table-maintenance-sql

12.5.2.2 `BACKUP TABLE' Syntax
..............................

     BACKUP TABLE TBL_NAME [, TBL_NAME] ... TO '/PATH/TO/BACKUP/DIRECTORY'

*Note*:

This statement is deprecated. We are working on a better replacement
for it that will provide online backup capabilities. In the meantime,
the `mysqlhotcopy' script can be used instead.

`BACKUP TABLE' copies to the backup directory the minimum number of
table files needed to restore the table, after flushing any buffered
changes to disk. The statement works only for `MyISAM' tables. It
copies the `.frm' definition and `.MYD' data files. The `.MYI' index
file can be rebuilt from those two files. The directory should be
specified as a full pathname.  To restore the table, use `RESTORE
TABLE'.

During the backup, a read lock is held for each table, one at time, as
they are being backed up. If you want to back up several tables as a
snapshot (preventing any of them from being changed during the backup
operation), issue a `LOCK TABLES' statement first, to obtain a read
lock for all tables in the group.

`BACKUP TABLE' returns a result set with the following columns:

*Column*    *Value*
`Table'     The table name
`Op'        Always `backup'
`Msg_type'  One of `status', `error', `info', or
            `warning'
`Msg_text'  The message


File: manual.info,  Node: check-table,  Next: checksum-table,  Prev: backup-table,  Up: table-maintenance-sql

12.5.2.3 `CHECK TABLE' Syntax
.............................

     CHECK TABLE TBL_NAME [, TBL_NAME] ... [OPTION] ...

     OPTION = {FOR UPGRADE | QUICK | FAST | MEDIUM | EXTENDED | CHANGED}

`CHECK TABLE' checks a table or tables for errors. `CHECK TABLE' works
for `MyISAM', `InnoDB', and `ARCHIVE' tables. Starting with MySQL 5.1.9,
`CHECK' is also valid for `CSV' tables, see *Note csv-storage-engine::.
For `MyISAM' tables, the key statistics are updated as well.

`CHECK TABLE' can also check views for problems, such as tables that
are referenced in the view definition that no longer exist.

`CHECK TABLE' is not supported for partitioned tables.

`CHECK TABLE' returns a result set with the following columns:

*Column*    *Value*
`Table'     The table name
`Op'        Always `check'
`Msg_type'  One of `status', `error', `info', or
            `warning'
`Msg_text'  The message

Note that the statement might produce many rows of information for each
checked table. The last row has a `Msg_type' value of `status' and the
`Msg_text' normally should be `OK'. If you don't get `OK', or `Table is
already up to date' you should normally run a repair of the table. See
*Note table-maintenance::. `Table is already up to date' means that the
storage engine for the table indicated that there was no need to check
the table.

The `FOR UPGRADE' option checks whether the named tables are compatible
with the current version of MySQL.  This option was added in MySQL
5.1.7. With `FOR UPGRADE', the server checks each table to determine
whether there have been any incompatible changes in any of the table's
data types or indexes since the table was created. If not, the check
succeeds. Otherwise, if there is a possible incompatibility, the server
runs a full check on the table (which might take some time). If the
full check succeeds, the server marks the table's `.frm' file with the
current MySQL version number. Marking the `.frm' file ensures that
further checks for the table with the same version of the server will
be fast.

Incompatibilities might occur because the storage format for a data
type has changed or because its sort order has changed. Our aim is to
avoid these changes, but occasionally they are necessary to correct
problems that would be worse than an incompatibility between releases.

Currently, `FOR UPGRADE' discovers these incompatibilities:

   * The indexing order for end-space in `TEXT' columns for `InnoDB' and
     `MyISAM' tables changed between MySQL 4.1 and 5.0.

   * The storage method of the new `DECIMAL' data type changed between
     MySQL 5.0.3 and 5.0.5.

   * As of MySQL 5.1.25, if your table was created by a different
     version of the MySQL server than the one you are currently
     running, `FOR UPGRADE' indicates that the table has an `.frm' file
     with an incompatible version. In this case, the result set returned
     by `CHECK TABLE' contains a line with a `Msg_type' value of
     `error' and a `Msg_text' value of `Table upgrade required. Please
     do "REPAIR TABLE `TBL_NAME`" to fix it!'

The other check options that can be given are shown in the following
table. These options are passed to the storage engine, which may use
them or not. `MyISAM' uses them; they are ignored for `InnoDB' tables
and views.

*Type*      *Meaning*
`QUICK'     Do not scan the rows to check for incorrect links.
`FAST'      Check only tables that have not been closed properly.
`CHANGED'   Check only tables that have been changed since the last
            check or that have not been closed properly.
`MEDIUM'    Scan rows to verify that deleted links are valid. This also
            calculates a key checksum for the rows and verifies this
            with a calculated checksum for the keys.
`EXTENDED'  Do a full key lookup for all keys for each row. This ensures
            that the table is 100% consistent, but takes a long time.

If none of the options `QUICK', `MEDIUM', or `EXTENDED' are specified,
the default check type for dynamic-format `MyISAM' tables is `MEDIUM'.
This has the same result as running `myisamchk --medium-check TBL_NAME'
on the table. The default check type also is `MEDIUM' for static-format
`MyISAM' tables, unless `CHANGED' or `FAST' is specified. In that case,
the default is `QUICK'. The row scan is skipped for `CHANGED' and
`FAST' because the rows are very seldom corrupted.

You can combine check options, as in the following example that does a
quick check on the table to determine whether it was closed properly:

     CHECK TABLE test_table FAST QUICK;

*Note*:

In some cases, `CHECK TABLE' changes the table. This happens if the
table is marked as `corrupted' or `not closed properly' but `CHECK
TABLE' does not find any problems in the table. In this case, `CHECK
TABLE' marks the table as okay.

If a table is corrupted, it is most likely that the problem is in the
indexes and not in the data part. All of the preceding check types
check the indexes thoroughly and should thus find most errors.

If you just want to check a table that you assume is okay, you should
use no check options or the `QUICK' option. The latter should be used
when you are in a hurry and can take the very small risk that `QUICK'
does not find an error in the data file. (In most cases, under normal
usage, MySQL should find any error in the data file. If this happens,
the table is marked as `corrupted' and cannot be used until it is
repaired.)

`FAST' and `CHANGED' are mostly intended to be used from a script (for
example, to be executed from `cron') if you want to check tables from
time to time. In most cases, `FAST' is to be preferred over `CHANGED'.
(The only case when it is not preferred is when you suspect that you
have found a bug in the `MyISAM' code.)

`EXTENDED' is to be used only after you have run a normal check but
still get strange errors from a table when MySQL tries to update a row
or find a row by key. This is very unlikely if a normal check has
succeeded.

Use of `CHECK TABLE ... EXTENDED' might influence the execution plan
generated by the query optimizer.

Some problems reported by `CHECK TABLE' cannot be corrected
automatically:

   * `Found row where the auto_increment column has the value 0'.

     This means that you have a row in the table where the
     `AUTO_INCREMENT' index column contains the value 0. (It is
     possible to create a row where the `AUTO_INCREMENT' column is 0 by
     explicitly setting the column to 0 with an `UPDATE' statement.)

     This is not an error in itself, but could cause trouble if you
     decide to dump the table and restore it or do an `ALTER TABLE' on
     the table. In this case, the `AUTO_INCREMENT' column changes value
     according to the rules of `AUTO_INCREMENT' columns, which could
     cause problems such as a duplicate-key error.

     To get rid of the warning, simply execute an `UPDATE' statement to
     set the column to some value other than 0.

   * If `CHECK TABLE' finds a problem for an `InnoDB' table, the server
     shuts down to prevent error propagation. Details of the error will
     be written to the error log.


File: manual.info,  Node: checksum-table,  Next: optimize-table,  Prev: check-table,  Up: table-maintenance-sql

12.5.2.4 `CHECKSUM TABLE' Syntax
................................

     CHECKSUM TABLE TBL_NAME [, TBL_NAME] ... [ QUICK | EXTENDED ]

`CHECKSUM TABLE' reports a table checksum.

With `QUICK', the live table checksum is reported if it is available,
or `NULL' otherwise. This is very fast. A live checksum is enabled by
specifying the `CHECKSUM=1' table option when you create the table;
currently, this is supported only for `MyISAM' tables. See *Note
create-table::.

With `EXTENDED', the entire table is read row by row and the checksum
is calculated. This can be very slow for large tables.

If neither `QUICK' nor `EXTENDED' is specified, MySQL returns a live
checksum if the table storage engine supports it and scans the table
otherwise.

For a non-existent table, `CHECKSUM TABLE' returns `NULL' and generates
a warning.

The checksum value depends on the table row format. If the row format
changes, the checksum also changes. For example, the storage format for
`VARCHAR' changed between MySQL 4.1 and 5.0, so if a 4.1 table is
upgraded to MySQL 5.0, the checksum value may change.


File: manual.info,  Node: optimize-table,  Next: repair-table,  Prev: checksum-table,  Up: table-maintenance-sql

12.5.2.5 `OPTIMIZE TABLE' Syntax
................................

     OPTIMIZE [LOCAL | NO_WRITE_TO_BINLOG] TABLE TBL_NAME [, TBL_NAME] ...

`OPTIMIZE TABLE' should be used if you have deleted a large part of a
table or if you have made many changes to a table with variable-length
rows (tables that have `VARCHAR', `VARBINARY', `BLOB', or `TEXT'
columns).  Deleted rows are maintained in a linked list and subsequent
`INSERT' operations reuse old row positions.  You can use `OPTIMIZE
TABLE' to reclaim the unused space and to defragment the data file.

This statement requires `SELECT' and `INSERT' privileges for the table.

`OPTIMIZE TABLE' is not supported for partitioned tables. See *Note
partitioning-maintenance::, for information about alternatives.

In most setups, you need not run `OPTIMIZE TABLE' at all. Even if you
do a lot of updates to variable-length rows, it is not likely that you
need to do this more than once a week or month and only on certain
tables.

`OPTIMIZE TABLE' works _only_ for `MyISAM', `InnoDB', and `ARCHIVE'
tables. It does _not_ work for tables created using any other storage
engine, including `NDB' Disk Data tables.

In MySQL Cluster NDB 6.3.7 and later MySQL Cluster NDB 6.3 releases,
`OPTIMIZE TABLE' is supported for dynamic columns of in-memory `NDB'
tables. The performance of `OPTIMIZE' on Cluster tables can be tuned by
adjusting the value of the `ndb_optimization_delay' system variable,
which controls the number of milliseconds to wait between processing
batches of rows by `OPTIMIZE TABLE'. See *Note
mysql-cluster-limitations-resolved::, for more information.

Beginning with MySQL Cluster NDB 6.3.8, `OPTIMIZE TABLE' can be
interrupted by (for example) killing the SQL thread performing the
`OPTIMIZE' operation.

For `MyISAM' tables, `OPTIMIZE TABLE' works as follows:

  1. If the table has deleted or split rows, repair the table.

  2. If the index pages are not sorted, sort them.

  3. If the table's statistics are not up to date (and the repair could
     not be accomplished by sorting the index), update them.

For `InnoDB' tables, `OPTIMIZE TABLE' is mapped to `ALTER TABLE', which
rebuilds the table to update index statistics and free unused space in
the clustered index.

You can make `OPTIMIZE TABLE' work on other storage engines by starting
`mysqld' with the `--skip-new' or `--safe-mode' option. In this case,
`OPTIMIZE TABLE' is just mapped to `ALTER TABLE'.

`OPTIMIZE TABLE' returns a result set with the following columns:

*Column*    *Value*
`Table'     The table name
`Op'        Always `optimize'
`Msg_type'  One of `status', `error', `info', or
            `warning'
`Msg_text'  The message

Note that MySQL locks the table during the time `OPTIMIZE TABLE' is
running.

By default, `OPTIMIZE TABLE' statements are written to the binary log
so that such statements used on a MySQL server acting as a replication
master will be replicated to replication slaves. Logging can be
suppressed with the optional `NO_WRITE_TO_BINLOG' keyword or its alias
`LOCAL'.

`OPTIMIZE TABLE' does not sort R-tree indexes, such as spatial indexes
on `POINT' columns.  (Bug#23578 (http://bugs.mysql.com/23578))


File: manual.info,  Node: repair-table,  Next: restore-table,  Prev: optimize-table,  Up: table-maintenance-sql

12.5.2.6 `REPAIR TABLE' Syntax
..............................

     REPAIR [LOCAL | NO_WRITE_TO_BINLOG] TABLE
         TBL_NAME [, TBL_NAME] ... [QUICK] [EXTENDED] [USE_FRM]

`REPAIR TABLE' repairs a possibly corrupted table. By default, it has
the same effect as `myisamchk --recover TBL_NAME'.  `REPAIR TABLE'
works for `MyISAM' and for `ARCHIVE' tables. Starting with MySQL 5.1.9,
`REPAIR' is also valid for `CSV' tables. See *Note
myisam-storage-engine::, and *Note archive-storage-engine::, and *Note
csv-storage-engine::

This statement requires `SELECT' and `INSERT' privileges for the table.

`REPAIR TABLE' is not supported for partitioned tables. See *Note
partitioning-maintenance::, for information about alternatives.

Normally, you should never have to run this statement. However, if
disaster strikes, `REPAIR TABLE' is very likely to get back all your
data from a `MyISAM' table. If your tables become corrupted often, you
should try to find the reason for it, to eliminate the need to use
`REPAIR TABLE'. See *Note crashing::, and *Note myisam-table-problems::.

*Caution*:

It is best to make a backup of a table before performing a table repair
operation; under some circumstances the operation might cause data
loss. Possible causes include but are not limited to filesystem errors.

*Warning*:

If the server dies during a `REPAIR TABLE' operation, it is essential
after restarting it that you immediately execute another `REPAIR TABLE'
statement for the table before performing any other operations on it.
(It is always a good idea to start by making a backup.)  In the worst
case, you might have a new clean index file without information about
the data file, and then the next operation you perform could overwrite
the data file. This is an unlikely but possible scenario.

`REPAIR TABLE' returns a result set with the following columns:

*Column*    *Value*
`Table'     The table name
`Op'        Always `repair'
`Msg_type'  One of `status', `error', `info', or
            `warning'
`Msg_text'  The message

The `REPAIR TABLE' statement might produce many rows of information for
each repaired table. The last row has a `Msg_type' value of `status'
and `Msg_test' normally should be `OK'. If you do not get `OK', you
should try repairing the table with `myisamchk --safe-recover'.
(`REPAIR TABLE' does not yet implement all the options of `myisamchk'.)
With `myisamchk --safe-recover', you can also use options that `REPAIR
TABLE' does not support, such as `--max-record-length'.

If `QUICK' is given, `REPAIR TABLE' tries to repair only the index
tree. This type of repair is like that done by `myisamchk --recover
--quick'.

If you use `EXTENDED', MySQL creates the index row by row instead of
creating one index at a time with sorting.  This type of repair is like
that done by `myisamchk --safe-recover'.

There is also a `USE_FRM' mode available for `REPAIR TABLE'. Use this
if the `.MYI' index file is missing or if its header is corrupted. In
this mode, MySQL re-creates the `.MYI' file using information from the
`.frm' file. This kind of repair cannot be done with `myisamchk'.

*Note*:

Use this mode _only_ if you cannot use regular `REPAIR' modes. The
`.MYI' header contains important table metadata (in particular, current
`AUTO_INCREMENT' value and `Delete link') that are lost in `REPAIR ...
USE_FRM'. Don't use `USE_FRM' if the table is compressed because this
information is also stored in the `.MYI' file.

If `USE_FRM' is _not_ used, then a `REPAIR TABLE' checks the table to
see whether an upgrade is required and if it is necessary performs the
upgrade, following the same rules as `CHECK TABLE ... FOR UPGRADE'. See
*Note check-table::, for more information. As of MySQL 5.1.25, `REPAIR
TABLE' without `USE_FRM' upgrades the `.frm' file to the current
version.

*Caution*:

As of MySQL 5.1.25, if you use `USE_FRM' and your table was created by
a different version of the MySQL server than the one you are currently
running, `REPAIR TABLE' will not attempt to repair the table. In this
case, the result set returned by `REPAIR TABLE' contains a line with a
`Msg_type' value of `error' and a `Msg_text' value of `Failed repairing
incompatible .FRM file'.

Prior to MySQL 5.1.25, _do not use_ `USE_FRM' if your table was created
by a different version of the MySQL server. Doing so risks the loss of
all rows in the table. It is particularly dangerous to use `USE_FRM'
after the server returns this message:

     Table upgrade required. Please do
     "REPAIR TABLE `TBL_NAME`" to fix it!

By default, `REPAIR TABLE' statements are written to the binary log so
that such statements used on a MySQL server acting as a replication
master will be replicated to replication slaves. Logging can be
suppressed with the optional `NO_WRITE_TO_BINLOG' keyword or its alias
`LOCAL'.


File: manual.info,  Node: restore-table,  Prev: repair-table,  Up: table-maintenance-sql

12.5.2.7 `RESTORE TABLE' Syntax
...............................

     RESTORE TABLE TBL_NAME [, TBL_NAME] ... FROM '/PATH/TO/BACKUP/DIRECTORY'

`RESTORE TABLE' restores the table or tables from a backup that was
made with `BACKUP TABLE'. The directory should be specified as a full
pathname.

Existing tables are not overwritten; if you try to restore over an
existing table, an error occurs. Just as for `BACKUP TABLE', `RESTORE
TABLE' currently works only for `MyISAM' tables. Restored tables are
not replicated from master to slave.

The backup for each table consists of its `.frm' format file and `.MYD'
data file. The restore operation restores those files, and then uses
them to rebuild the `.MYI' index file. Restoring takes longer than
backing up due to the need to rebuild the indexes. The more indexes the
table has, the longer it takes.

`RESTORE TABLE' returns a result set with the following columns:

*Column*    *Value*
`Table'     The table name
`Op'        Always `restore'
`Msg_type'  One of `status', `error', `info', or
            `warning'
`Msg_text'  The message


File: manual.info,  Node: plugin-sql,  Next: set-option,  Prev: table-maintenance-sql,  Up: sql-syntax-server-administration

12.5.3 Plugin and User-Defined Function Statements
--------------------------------------------------

* Menu:

* create-function-udf::          `CREATE FUNCTION' Syntax
* drop-function-udf::            `DROP FUNCTION' Syntax
* install-plugin::               `INSTALL PLUGIN' Syntax
* uninstall-plugin::             `UNINSTALL PLUGIN' Syntax


File: manual.info,  Node: create-function-udf,  Next: drop-function-udf,  Prev: plugin-sql,  Up: plugin-sql

12.5.3.1 `CREATE FUNCTION' Syntax
.................................

     CREATE [AGGREGATE] FUNCTION FUNCTION_NAME RETURNS {STRING|INTEGER|REAL|DECIMAL}
         SONAME SHARED_LIBRARY_NAME

A user-defined function (UDF) is a way to extend MySQL with a new
function that works like a native (built-in) MySQL function such as
`ABS()' or `CONCAT()'.

FUNCTION_NAME is the name that should be used in SQL statements to
invoke the function. The `RETURNS' clause indicates the type of the
function's return value. `DECIMAL' is a legal value after `RETURNS',
but currently `DECIMAL' functions return string values and should be
written like `STRING' functions.

SHARED_LIBRARY_NAME is the basename of the shared object file that
contains the code that implements the function. The file must be
located in the plugin directory.  This directory is given by the value
of the `plugin_dir' system variable.

*Note*:

This is a change in MySQL 5.1. For earlier versions of MySQL, the
shared object can be located in any directory that is searched by your
system's dynamic linker.

To create a function, you must have the `INSERT' and privilege for the
`mysql' database. This is necessary because `CREATE FUNCTION' adds a
row to the `mysql.func' system table that records the function's name,
type, and shared library name. If you do not have this table, you
should run the `mysql_upgrade' command to create it. See *Note
mysql-upgrade::.

An active function is one that has been loaded with `CREATE FUNCTION'
and not removed with `DROP FUNCTION'. All active functions are reloaded
each time the server starts, unless you start `mysqld' with the
`--skip-grant-tables' option. In this case, UDF initialization is
skipped and UDFs are unavailable.

For instructions on writing user-defined functions, see *Note
adding-udf::. For the UDF mechanism to work, functions must be written
in C or C++ (or another language that can use C calling conventions),
your operating system must support dynamic loading and you must have
compiled `mysqld' dynamically (not statically).

An `AGGREGATE' function works exactly like a native MySQL aggregate
(summary) function such as `SUM' or `COUNT()'. For `AGGREGATE' to work,
your `mysql.func' table must contain a `type' column. If your
`mysql.func' table does not have this column, you should run the
`mysql_upgrade' program to create it (see *Note mysql-upgrade::).

*Note*:

To upgrade the shared library associated with a UDF, issue a `DROP
FUNCTION' statement, upgrade the shared library, and then issue a
`CREATE FUNCTION' statement. If you upgrade the shared library first
and then use `DROP FUNCTION', the server may crash.


File: manual.info,  Node: drop-function-udf,  Next: install-plugin,  Prev: create-function-udf,  Up: plugin-sql

12.5.3.2 `DROP FUNCTION' Syntax
...............................

     DROP FUNCTION FUNCTION_NAME

This statement drops the user-defined function (UDF) named
FUNCTION_NAME.

To drop a function, you must have the `DELETE' privilege for the
`mysql' database. This is because `DROP FUNCTION' removes a row from the
`mysql.func' system table that records the function's name, type, and
shared library name.

*Note*:

To upgrade the shared library associated with a UDF, issue a `DROP
FUNCTION' statement, upgrade the shared library, and then issue a
`CREATE FUNCTION' statement. If you upgrade the shared library first
and then use `DROP FUNCTION', the server may crash.

`DROP FUNCTION' is also used to drop stored functions (see *Note
drop-procedure::).


File: manual.info,  Node: install-plugin,  Next: uninstall-plugin,  Prev: drop-function-udf,  Up: plugin-sql

12.5.3.3 `INSTALL PLUGIN' Syntax
................................

     INSTALL PLUGIN PLUGIN_NAME SONAME 'PLUGIN_LIBRARY'

This statement installs a plugin.

PLUGIN_NAME is the name of the plugin as defined in the plugin
declaration structure contained in the library file. Plugin name case
sensitivity is determined by the host system filename semantics.

PLUGIN_LIBRARY is the name of the shared library that contains the
plugin code. The name includes the filename extension (for example,
`libmyplugin.so' or `libmyplugin.dylib').

The shared library must be located in the plugin directory (that is,
the directory named by the `plugin_dir' system variable). The library
must be in the plugin directory itself, not in a subdirectory. By
default, `plugin_dir' is `plugin' directory under the directory named
by the `pkglibdir' configuration variable, but it can be changed by
setting the value of `plugin_dir' at server startup. For example, set
its value in a `my.cnf' file:

     [mysqld]
     plugin_dir=/PATH/TO/PLUGIN/DIRECTORY

If the value of `plugin_dir' is a relative pathname, it is taken to be
relative to the MySQL base directory (the value of the `basedir' system
variable).

`INSTALL PLUGIN' adds a line to the `mysql.plugin' table that describes
the `plugin'. This table contains the plugin name and library filename.

`INSTALL PLUGIN' also loads and initializes the plugin code to make the
plugin available for use. A plugin is initialized by executing its
initialization function, which handles any setup that the plugin must
perform before it can be used.

To use `INSTALL PLUGIN', you must have the `INSERT privilege' for the
`mysql.plugin' table.

At server startup, the server loads and initializes any plugin that is
listed in the `mysql.plugin' table.  This means that a plugin is
installed with `INSTALL PLUGIN' only once, not every time the server
starts.  Plugin loading at startup does not occur if the server is
started with the `--skip-grant-tables' option.

When the server shuts down, it executes the deinitialization function
for each plugin that is loaded so that the plugin has a change to
perform any final cleanup.

To remove a plugin entirely, use the `UNINSTALL PLUGIN' statement:

To see what plugins are installed, use the `SHOW PLUGIN' statement.

If you recompile a plugin library and need to reinstall it, you can use
either of the following procedures:

   * Use `UNINSTALL PLUGIN' to uninstall all plugins in the library,
     install the new plugin library file in the plugin directory, and
     then use `INSTALL PLUGIN' to install all plugins in the library.
     This procedure has the advantage that it can be used without
     stopping the server. However, if the plugin library contains many
     plugins, you must issue many `INSTALL PLUGIN' and `UNINSTALL
     PLUGIN' statements.

   * Alternatively, stop the server, install the new plugin library
     file in the plugin directory, and then restart the server.


File: manual.info,  Node: uninstall-plugin,  Prev: install-plugin,  Up: plugin-sql

12.5.3.4 `UNINSTALL PLUGIN' Syntax
..................................

     UNINSTALL PLUGIN PLUGIN_NAME

This statement removes an installed plugin. You cannot uninstall a
plugin if any table that uses it is open.

PLUGIN_NAME must be the name of some plugin that is listed in the
`mysql.plugin' table. The server executes the plugin's deinitialization
function and removes the row for the plugin from the `mysql.plugin'
table, so that subsequent server restarts will not load and initialize
the plugin.  `UNINSTALL PLUGIN' does not remove the plugin's shared
library file.

To use `UNINSTALL PLUGIN', you must have the `DELETE' privilege for the
`mysql.plugin' table.

Plugin removal has implications for the use of associated tables. For
example, if a full-text parser plugin is associated with a `FULLTEXT'
index on the table, uninstalling the plugin makes the table unusable.
Any attempt to access the table results in an error. The table cannot
even be opened, so you cannot drop an index for which the plugin is
used. This means that uninstalling a plugin is something to do with
care unless you do not care about the table contents. If you are
uninstalling a plugin with no intention of reinstalling it later and
you care about the table contents, you should dump the table with
`mysqldump' and remove the `WITH PARSER' clause from the dumped `CREATE
TABLE' statement so that you can reload the table later. If you do not
care about the table, `DROP TABLE' can be used even if any plugins
associated with the table are missing.


File: manual.info,  Node: set-option,  Next: show,  Prev: plugin-sql,  Up: sql-syntax-server-administration

12.5.4 `SET' Syntax
-------------------

     SET VARIABLE_ASSIGNMENT [, VARIABLE_ASSIGNMENT] ...

     VARIABLE_ASSIGNMENT:
           USER_VAR_NAME = EXPR
         | [GLOBAL | SESSION] SYSTEM_VAR_NAME = EXPR
         | [@@global. | @@session. | @@]SYSTEM_VAR_NAME = EXPR

The `SET' statement assigns values to different types of variables that
affect the operation of the server or your client. Older versions of
MySQL employed `SET OPTION', but this syntax is deprecated in favor of
`SET' without `OPTION'.

This section describes use of `SET' for assigning values to system
variables or user variables. For general information about these types
of variables, see *Note server-system-variables::, *Note
server-session-variables::, and *Note user-variables::. System
variables also can be set at server startup, as described in *Note
using-system-variables::.

Some variants of `SET' syntax are used in other contexts:

   * `SET CHARACTER SET' and `SET NAMES' assign values to character set
     and collation variables associated with the connection to the
     server.  `SET ONESHOT' is used for replication. These variants are
     described later in this section.

   * `SET PASSWORD' assigns account passwords. See *Note set-password::.

   * `SET TRANSACTION ISOLATION LEVEL' sets the isolation level for
     transaction processing. See *Note set-transaction::.

   * `SET' is used within stored routines to assign values to local
     routine variables. See *Note set-statement::.

The following discussion shows the different `SET' syntaxes that you
can use to set variables.  The examples use the `=' assignment
operator, but the `:=' operator also is allowable.

A user variable is written as `@VAR_NAME' and can be set as follows:

     SET @VAR_NAME = EXPR;

Many system variables are dynamic and can be changed while the server
runs by using the `SET' statement. For a list, see *Note
dynamic-system-variables::. To change a system variable with `SET',
refer to it as VAR_NAME, optionally preceded by a modifier:

   * To indicate explicitly that a variable is a global variable,
     precede its name by `GLOBAL' or `@@global.'. The `SUPER' privilege
     is required to set global variables.

   * To indicate explicitly that a variable is a session variable,
     precede its name by `SESSION', `@@session.', or `@@'.  Setting a
     session variable requires no special privilege, but a client can
     change only its own session variables, not those of any other
     client.

   * `LOCAL' and `@@local.' are synonyms for `SESSION' and `@@session.'.

   * If no modifier is present, `SET' changes the session variable.

MySQL Enterprise

The MySQL Enterprise Monitor makes extensive use of system variables to
determine the state of your server. For more information see
`advisors.html'.

A `SET' statement can contain multiple variable assignments, separated
by commas. If you set several system variables, the most recent
`GLOBAL' or `SESSION' modifier in the statement is used for following
variables that have no modifier specified.

Examples:

     SET sort_buffer_size=10000;
     SET @@local.sort_buffer_size=10000;
     SET GLOBAL sort_buffer_size=1000000, SESSION sort_buffer_size=1000000;
     SET @@sort_buffer_size=1000000;
     SET @@global.sort_buffer_size=1000000, @@local.sort_buffer_size=1000000;

The `@@VAR_NAME' syntax for system variables is supported for
compatibility with some other database systems.

If you change a session system variable, the value remains in effect
until your session ends or until you change the variable to a different
value. The change is not visible to other clients.

If you change a global system variable, the value is remembered and
used for new connections until the server restarts. (To make a global
system variable setting permanent, you should set it in an option
file.) The change is visible to any client that accesses that global
variable. However, the change affects the corresponding session
variable only for clients that connect after the change. The global
variable change does not affect the session variable for any client
that is currently connected (not even that of the client that issues
the `SET GLOBAL' statement).

To prevent incorrect usage, MySQL produces an error if you use `SET
GLOBAL' with a variable that can only be used with `SET SESSION' or if
you do not specify `GLOBAL' (or `@@global.') when setting a global
variable.

To set a `SESSION' variable to the `GLOBAL' value or a `GLOBAL' value
to the compiled-in MySQL default value, use the `DEFAULT' keyword. For
example, the following two statements are identical in setting the
session value of `max_join_size' to the global value:

     SET max_join_size=DEFAULT;
     SET @@session.max_join_size=@@global.max_join_size;

Not all system variables can be set to `DEFAULT'.  In such cases, use
of `DEFAULT' results in an error.

You can refer to the values of specific global or sesson system
variables in expressions by using one of the `@@'-modifiers. For
example, you can retrieve values in a `SELECT' statement like this:

     SELECT @@global.sql_mode, @@session.sql_mode, @@sql_mode;

When you refer to a system variable in an expression as `@@VAR_NAME'
(that is, when you do not specify `@@global.' or `@@session.'), MySQL
returns the session value if it exists and the global value otherwise.
(This differs from `SET @@VAR_NAME = VALUE', which always refers to the
session value.)

Suffixes for specifying a value multiplier can be used when setting a
variable at server startup, but not to set the value with `SET' at
runtime. On the other hand, with `SET' you can assign a variable's
value using an expression, which is not true when you set a variable at
server startup. For example, the first of the following lines is legal
at server startup, but the second is not:

     shell> mysql --max_allowed_packet=16M
     shell> mysql --max_allowed_packet=16*1024*1024

Conversely, the second of the following lines is legal at runtime, but
the first is not:

     mysql> SET GLOBAL max_allowed_packet=16M;
     mysql> SET GLOBAL max_allowed_packet=16*1024*1024;

To display system variables names and values, use the `SHOW VARIABLES'
statement. (See *Note show-variables::.)

The following list describes `SET' options that have non-standard
syntax (that is, options that are not set with `NAME = VALUE' syntax).

   * `CHARACTER SET {CHARSET_NAME | DEFAULT}'

     This maps all strings from and to the client with the given
     mapping. You can add new mappings by editing `sql/convert.cc' in
     the MySQL source distribution. `SET CHARACTER SET' sets three
     session system variables: `character_set_client' and
     `character_set_results' are set to the given character set, and
     `character_set_connection' to the value of
     `character_set_database'. See *Note charset-connection::.

     The default mapping can be restored by using the value `DEFAULT'.
     The default depends on the server configuration.

     `ucs2' cannot be used as a client character set, which means that
     it does not work for `SET CHARACTER SET'.

   * `NAMES {'CHARSET_NAME' [COLLATE 'COLLATION_NAME'] | DEFAULT}'

     `SET NAMES' sets the three session system variables
     `character_set_client', `character_set_connection', and
     `character_set_results' to the given character set. Setting
     `character_set_connection' to `charset_name' also sets
     `collation_connection' to the default collation for
     `charset_name'. The optional `COLLATE' clause may be used to
     specify a collation explicitly. See *Note charset-connection::.

     The default mapping can be restored by using a value of `DEFAULT'.
     The default depends on the server configuration.

     `ucs2' cannot be used as a client character set, which means that
     it does not work for `SET NAMES'.

   * `ONE_SHOT'

     This option is a modifier, not a variable. It can be used to
     influence the effect of variables that set the character set, the
     collation, and the time zone. `ONE_SHOT' is primarily used for
     replication purposes: `mysqlbinlog' uses `SET ONE_SHOT' to modify
     temporarily the values of character set, collation, and time zone
     variables to reflect at rollforward what they were originally.
     `ONE_SHOT' is for internal use only and is deprecated for MySQL
     5.0 and up.

     You cannot use `ONE_SHOT' with other than the allowed set of
     variables; if you try, you get an error like this:

          mysql> SET ONE_SHOT max_allowed_packet = 1;
          ERROR 1382 (HY000): The 'SET ONE_SHOT' syntax is reserved for purposes
          internal to the MySQL server

     If `ONE_SHOT' is used with the allowed variables, it changes the
     variables as requested, but only for the next non-`SET' statement.
     After that, the server resets all character set, collation, and
     time zone-related system variables to their previous values.
     Example:

          mysql> SET ONE_SHOT character_set_connection = latin5;

          mysql> SET ONE_SHOT collation_connection = latin5_turkish_ci;

          mysql> SHOW VARIABLES LIKE '%_connection';
          +--------------------------+-------------------+
          | Variable_name            | Value             |
          +--------------------------+-------------------+
          | character_set_connection | latin5            |
          | collation_connection     | latin5_turkish_ci |
          +--------------------------+-------------------+

          mysql> SHOW VARIABLES LIKE '%_connection';
          +--------------------------+-------------------+
          | Variable_name            | Value             |
          +--------------------------+-------------------+
          | character_set_connection | latin1            |
          | collation_connection     | latin1_swedish_ci |
          +--------------------------+-------------------+


File: manual.info,  Node: show,  Next: other-administrative-sql,  Prev: set-option,  Up: sql-syntax-server-administration

12.5.5 `SHOW' Syntax
--------------------

* Menu:

* show-authors::                 `SHOW AUTHORS' Syntax
* show-binary-logs::             `SHOW BINARY LOGS' Syntax
* show-binlog-events::           `SHOW BINLOG EVENTS' Syntax
* show-character-set::           `SHOW CHARACTER SET' Syntax
* show-collation::               `SHOW COLLATION' Syntax
* show-columns::                 `SHOW COLUMNS' Syntax
* show-contributors::            `SHOW CONTRIBUTORS' Syntax
* show-create-database::         `SHOW CREATE DATABASE' Syntax
* show-create-event::            `SHOW CREATE EVENT'
* show-create-procedure::        `SHOW CREATE PROCEDURE' and `SHOW CREATE FUNCTION' Syntax
* show-create-table::            `SHOW CREATE TABLE' Syntax
* show-create-trigger::          `SHOW CREATE TRIGGER' Syntax
* show-create-view::             `SHOW CREATE VIEW' Syntax
* show-databases::               `SHOW DATABASES' Syntax
* show-engine::                  `SHOW ENGINE' Syntax
* show-engines::                 `SHOW ENGINES' Syntax
* show-errors::                  `SHOW ERRORS' Syntax
* show-events::                  `SHOW EVENTS'
* show-grants::                  `SHOW GRANTS' Syntax
* show-index::                   `SHOW INDEX' Syntax
* show-innodb-status::           `SHOW INNODB STATUS' Syntax
* show-master-status::           `SHOW MASTER STATUS' Syntax
* show-open-tables::             `SHOW OPEN TABLES' Syntax
* show-plugins::                 `SHOW PLUGINS' Syntax
* show-privileges::              `SHOW PRIVILEGES' Syntax
* show-procedure-code::          `SHOW PROCEDURE CODE' and `SHOW FUNCTION CODE' Syntax
* show-procedure-status::        `SHOW PROCEDURE STATUS' and `SHOW FUNCTION STATUS' Syntax
* show-processlist::             `SHOW PROCESSLIST' Syntax
* show-scheduler-status::        `SHOW SCHEDULER STATUS' Syntax
* show-slave-hosts::             `SHOW SLAVE HOSTS' Syntax
* show-slave-status::            `SHOW SLAVE STATUS' Syntax
* show-status::                  `SHOW STATUS' Syntax
* show-table-status::            `SHOW TABLE STATUS' Syntax
* show-tables::                  `SHOW TABLES' Syntax
* show-triggers::                `SHOW TRIGGERS' Syntax
* show-variables::               `SHOW VARIABLES' Syntax
* show-warnings::                `SHOW WARNINGS' Syntax

`SHOW' has many forms that provide information about databases, tables,
columns, or status information about the server. This section describes
those following:

     SHOW AUTHORS
     SHOW CHARACTER SET [LIKE_OR_WHERE]
     SHOW COLLATION [LIKE_OR_WHERE]
     SHOW [FULL] COLUMNS FROM TBL_NAME [FROM DB_NAME] [LIKE_OR_WHERE]
     SHOW CONTRIBUTORS
     SHOW CREATE DATABASE DB_NAME
     SHOW CREATE EVENT EVENT_NAME
     SHOW CREATE FUNCTION FUNCNAME
     SHOW CREATE PROCEDURE PROCNAME
     SHOW CREATE TABLE TBL_NAME
     SHOW CREATE TRIGGER TRIGGER_NAME
     SHOW CREATE VIEW VIEW_NAME
     SHOW DATABASES [LIKE_OR_WHERE]
     SHOW ENGINE ENGINE_NAME {STATUS | MUTEX}
     SHOW [STORAGE] ENGINES
     SHOW ERRORS [LIMIT [OFFSET,] ROW_COUNT]
     SHOW [FULL] EVENTS
     SHOW FUNCTION CODE SP_NAME
     SHOW FUNCTION STATUS [LIKE_OR_WHERE]
     SHOW GRANTS FOR USER
     SHOW INDEX FROM TBL_NAME [FROM DB_NAME]
     SHOW INNODB STATUS
     SHOW OPEN TABLES [FROM DB_NAME] [LIKE_OR_WHERE]
     SHOW PLUGINS
     SHOW PROCEDURE CODE SP_NAME
     SHOW PROCEDURE STATUS [LIKE_OR_WHERE]
     SHOW PRIVILEGES
     SHOW [FULL] PROCESSLIST
     SHOW SCHEDULER STATUS
     SHOW [GLOBAL | SESSION] STATUS [LIKE_OR_WHERE]
     SHOW TABLE STATUS [FROM DB_NAME] [LIKE_OR_WHERE]
     SHOW TABLES [FROM DB_NAME] [LIKE_OR_WHERE]
     SHOW TRIGGERS [FROM DB_NAME] [LIKE_OR_WHERE]
     SHOW [GLOBAL | SESSION] VARIABLES [LIKE_OR_WHERE]
     SHOW WARNINGS [LIMIT [OFFSET,] ROW_COUNT]

     LIKE_OR_WHERE:
         LIKE 'PATTERN'
       | WHERE EXPR

If the syntax for a given `SHOW' statement includes a `LIKE 'PATTERN''
part, `'PATTERN'' is a string that can contain the SQL ``%'' and ``_''
wildcard characters. The pattern is useful for restricting statement
output to matching values.

Several `SHOW' statements also accept a `WHERE' clause that provides
more flexibility in specifying which rows to display. See *Note
extended-show::.

Many MySQL APIs (such as PHP) allow you to treat the result returned
from a `SHOW' statement as you would a result set from a `SELECT'; see
*Note apis::, or your API documentation for more information. In
addition, you can work in SQL with results from queries on tables in
the `INFORMATION_SCHEMA' database, which you cannot easily do with
results from `SHOW' statements. See *Note information-schema::.


File: manual.info,  Node: show-authors,  Next: show-binary-logs,  Prev: show,  Up: show

12.5.5.1 `SHOW AUTHORS' Syntax
..............................

     SHOW AUTHORS

The `SHOW AUTHORS' statement displays information about the people who
work on MySQL. For each author, it displays `Name', `Location', and
`Comment' values.

This statement was added in MySQL 5.1.3.


File: manual.info,  Node: show-binary-logs,  Next: show-binlog-events,  Prev: show-authors,  Up: show

12.5.5.2 `SHOW BINARY LOGS' Syntax
..................................

     SHOW BINARY LOGS
     SHOW MASTER LOGS

Lists the binary log files on the server. This statement is used as
part of the procedure described in *Note purge-master-logs::, that
shows how to determine which logs can be purged.

     mysql> SHOW BINARY LOGS;
     +---------------+-----------+
     | Log_name      | File_size |
     +---------------+-----------+
     | binlog.000015 |    724935 |
     | binlog.000016 |    733481 |
     +---------------+-----------+

`SHOW MASTER LOGS' is equivalent to `SHOW BINARY LOGS'.


File: manual.info,  Node: show-binlog-events,  Next: show-character-set,  Prev: show-binary-logs,  Up: show

12.5.5.3 `SHOW BINLOG EVENTS' Syntax
....................................

     SHOW BINLOG EVENTS
        [IN 'LOG_NAME'] [FROM POS] [LIMIT [OFFSET,] ROW_COUNT]

Shows the events in the binary log. If you do not specify `'LOG_NAME'',
the first binary log is displayed.

The `LIMIT' clause has the same syntax as for the `SELECT' statement.
See *Note select::.

*Note*:

Issuing a `SHOW BINLOG EVENTS' with no `LIMIT' clause could start a
very time- and resource-consuming process because the server returns to
the client the complete contents of the binary log (which includes all
statements executed by the server that modify data). As an alternative
to `SHOW BINLOG EVENTS', use the `mysqlbinlog' utility to save the
binary log to a text file for later examination and analysis. See *Note
mysqlbinlog::.

*Note*:

Events relating to the setting of variables are not included in the
output from `SHOW BINLOG EVENTS'. To get complete coverage of events
within a binary log, use *Note `mysqlbinlog': mysqlbinlog.


File: manual.info,  Node: show-character-set,  Next: show-collation,  Prev: show-binlog-events,  Up: show

12.5.5.4 `SHOW CHARACTER SET' Syntax
....................................

     SHOW CHARACTER SET
         [LIKE 'PATTERN' | WHERE EXPR]

The `SHOW CHARACTER SET' statement shows all available character sets.
The `LIKE' clause, if present, indicates which character set names to
match. The `WHERE' clause can be given to select rows using more
general conditions, as discussed in *Note extended-show::. For example:

     mysql> SHOW CHARACTER SET LIKE 'latin%';
     +---------+-----------------------------+-------------------+--------+
     | Charset | Description                 | Default collation | Maxlen |
     +---------+-----------------------------+-------------------+--------+
     | latin1  | cp1252 West European        | latin1_swedish_ci |      1 |
     | latin2  | ISO 8859-2 Central European | latin2_general_ci |      1 |
     | latin5  | ISO 8859-9 Turkish          | latin5_turkish_ci |      1 |
     | latin7  | ISO 8859-13 Baltic          | latin7_general_ci |      1 |
     +---------+-----------------------------+-------------------+--------+

The `Maxlen' column shows the maximum number of bytes required to store
one character.


File: manual.info,  Node: show-collation,  Next: show-columns,  Prev: show-character-set,  Up: show

12.5.5.5 `SHOW COLLATION' Syntax
................................

     SHOW COLLATION
         [LIKE 'PATTERN' | WHERE EXPR]

The output from `SHOW COLLATION' includes all available character sets.
The `LIKE' clause, if present, indicates which collation names to
match. The `WHERE' clause can be given to select rows using more
general conditions, as discussed in *Note extended-show::. For example:

     mysql> SHOW COLLATION LIKE 'latin1%';
     +-------------------+---------+----+---------+----------+---------+
     | Collation         | Charset | Id | Default | Compiled | Sortlen |
     +-------------------+---------+----+---------+----------+---------+
     | latin1_german1_ci | latin1  |  5 |         |          |       0 |
     | latin1_swedish_ci | latin1  |  8 | Yes     | Yes      |       0 |
     | latin1_danish_ci  | latin1  | 15 |         |          |       0 |
     | latin1_german2_ci | latin1  | 31 |         | Yes      |       2 |
     | latin1_bin        | latin1  | 47 |         | Yes      |       0 |
     | latin1_general_ci | latin1  | 48 |         |          |       0 |
     | latin1_general_cs | latin1  | 49 |         |          |       0 |
     | latin1_spanish_ci | latin1  | 94 |         |          |       0 |
     +-------------------+---------+----+---------+----------+---------+

The `Default' column indicates whether a collation is the default for
its character set.  `Compiled' indicates whether the character set is
compiled into the server. `Sortlen' is related to the amount of memory
required to sort strings expressed in the character set.


File: manual.info,  Node: show-columns,  Next: show-contributors,  Prev: show-collation,  Up: show

12.5.5.6 `SHOW COLUMNS' Syntax
..............................

     SHOW [FULL] COLUMNS FROM TBL_NAME [FROM DB_NAME]
         [LIKE 'PATTERN' | WHERE EXPR]

`SHOW COLUMNS' displays information about the columns in a given table.
It also works for views. The `LIKE' clause, if present, indicates which
column names to match. The `WHERE' clause can be given to select rows
using more general conditions, as discussed in *Note extended-show::.

     mysql> SHOW COLUMNS FROM City;
     +------------+----------+------+-----+---------+----------------+
     | Field      | Type     | Null | Key | Default | Extra          |
     +------------+----------+------+-----+---------+----------------+
     | Id         | int(11)  | NO   | PRI | NULL    | auto_increment |
     | Name       | char(35) | NO   |     |         |                |
     | Country    | char(3)  | NO   | UNI |         |                |
     | District   | char(20) | YES  | MUL |         |                |
     | Population | int(11)  | NO   |     | 0       |                |
     +------------+----------+------+-----+---------+----------------+
     5 rows in set (0.00 sec)

If the data types differ from what you expect them to be based on a
`CREATE TABLE' statement, note that MySQL sometimes changes data types
when you create or alter a table.  The conditions under which this
occurs are described in *Note silent-column-changes::.

The `FULL' keyword causes the output to include the column collation
and comments, as well as the privileges you have for each column.

You can use DB_NAME.TBL_NAME as an alternative to the `TBL_NAME FROM
DB_NAME' syntax. In other words, these two statements are equivalent:

     mysql> SHOW COLUMNS FROM mytable FROM mydb;
     mysql> SHOW COLUMNS FROM mydb.mytable;

`SHOW COLUMNS' displays the following values for each table column:

`Field' indicates the column name.

`Type' indicates the column data type.

`Collation' indicates the collation for non-binary string columns, or
`NULL' for other columns. This value is displayed only if you use the
`FULL' keyword.

The `Null' field contains `YES' if `NULL' values can be stored in the
column, `NO' if not.

The `Key' field indicates whether the column is indexed:

   * If `Key' is empty, the column either is not indexed or is indexed
     only as a secondary column in a multiple-column, non-unique index.

   * If `Key' is `PRI', the column is a `PRIMARY KEY' or is one of the
     columns in a multiple-column `PRIMARY KEY'.

   * If `Key' is `UNI', the column is the first column of a
     unique-valued index that cannot contain `NULL' values.

   * If `Key' is `MUL', multiple occurrences of a given value are
     allowed within the column. The column is the first column of a
     non-unique index or a unique-valued index that can contain `NULL'
     values.

If more than one of the `Key' values applies to a given column of a
table, `Key' displays the one with the highest priority, in the order
`PRI', `UNI', `MUL'.

A `UNIQUE' index may be displayed as `PRI' if it cannot contain `NULL'
values and there is no `PRIMARY KEY' in the table. A `UNIQUE' index may
display as `MUL' if several columns form a composite `UNIQUE' index;
although the combination of the columns is unique, each column can
still hold multiple occurrences of a given value.

The `Default' field indicates the default value that is assigned to the
column.

The `Extra' field contains any additional information that is available
about a given column. In the example shown, the `Extra' field indicates
that the `Id' column was created with the `AUTO_INCREMENT' keyword.

`Privileges' indicates the privileges you have for the column. This
value is displayed only if you use the `FULL' keyword.

`Comment' indicates any comment the column has.  This value is
displayed only if you use the `FULL' keyword.

`SHOW FIELDS' is a synonym for `SHOW COLUMNS'. You can also list a
table's columns with the `mysqlshow DB_NAME TBL_NAME' command.

The `DESCRIBE' statement provides information similar to `SHOW
COLUMNS'. See *Note describe::.

The `SHOW CREATE TABLE', `SHOW TABLE STATUS', and `SHOW INDEX'
statements also provide information about tables. See *Note show::.


File: manual.info,  Node: show-contributors,  Next: show-create-database,  Prev: show-columns,  Up: show

12.5.5.7 `SHOW CONTRIBUTORS' Syntax
...................................

     SHOW CONTRIBUTORS

The `SHOW CONTRIBUTORS' statement displays information about the people
who contribute to MySQL source or to causes that MySQL AB supports. For
each contributor, it displays `Name', `Location', and `Comment' values.

This statement was added in MySQL 5.1.12.


File: manual.info,  Node: show-create-database,  Next: show-create-event,  Prev: show-contributors,  Up: show

12.5.5.8 `SHOW CREATE DATABASE' Syntax
......................................

     SHOW CREATE {DATABASE | SCHEMA} DB_NAME

Shows the `CREATE DATABASE' statement that creates the given database.
`SHOW CREATE SCHEMA' is a synonym for `SHOW CREATE DATABASE'.

     mysql> SHOW CREATE DATABASE test\G
     *************************** 1. row ***************************
            Database: test
     Create Database: CREATE DATABASE `test`
                      /*!40100 DEFAULT CHARACTER SET latin1 */

     mysql> SHOW CREATE SCHEMA test\G
     *************************** 1. row ***************************
            Database: test
     Create Database: CREATE DATABASE `test`
                      /*!40100 DEFAULT CHARACTER SET latin1 */

`SHOW CREATE DATABASE' quotes table and column names according to the
value of the `SQL_QUOTE_SHOW_CREATE' option. See *Note
server-session-variables::.


File: manual.info,  Node: show-create-event,  Next: show-create-procedure,  Prev: show-create-database,  Up: show

12.5.5.9 `SHOW CREATE EVENT'
............................

     SHOW CREATE EVENT EVENT_NAME

This statement displays the `CREATE EVENT' statement needed to
re-create a given event. For example (using the same event `e_daily'
defined and then altered in *Note show-events::):

     mysql> SHOW CREATE EVENT test.e_daily\G

     *************************** 1. row ***************************
                    Event: e_daily
             Create Event: CREATE EVENT e_daily
                             ON SCHEDULE EVERY 1 DAY
                             STARTS CURRENT_TIMESTAMP + INTERVAL 6 HOUR
                             ENABLE
                             COMMENT 'Saves total number of sessions and
                                      clears the table once per day.'
                             DO
                               BEGIN
                                 INSERT INTO site_activity.totals (when, total)
                                   SELECT CURRENT_TIMESTAMP, COUNT(*)
                                   FROM site_activity.sessions;
                                 DELETE FROM site_activity.sessions;
                               END
     character_set_client: latin1
     collation_connection: latin1_swedish_ci
       Database Collation: latin1_swedish_ci

`character_set_client' is the session value of the
`character_set_client' system variable when the event was created.
`collation_connection' is the session value of the
`collation_connection' system variable when the event was created.
`Database Collation' is the collation of the database with which the
event is associated.  These columns were added in MySQL 5.1.21.

Note that the output reflects the current status of the event
(`ENABLE') rather than the status with which it was created.

This statement was implemented in MySQL 5.1.6.


File: manual.info,  Node: show-create-procedure,  Next: show-create-table,  Prev: show-create-event,  Up: show

12.5.5.10 `SHOW CREATE PROCEDURE' and `SHOW CREATE FUNCTION' Syntax
...................................................................

     SHOW CREATE {PROCEDURE | FUNCTION} SP_NAME

These statements are MySQL extensions. Similar to `SHOW CREATE TABLE',
they return the exact string that can be used to re-create the named
routine. The statements require that you be the owner of the routine or
have `SELECT' access to the `mysql.proc' table. If you do not have
privileges for the routine itself, the value displayed for the `Create
Procedure' or `Create Function' field will be `NULL'.

     mysql> SHOW CREATE FUNCTION test.hello\G
     *************************** 1. row ***************************
                 Function: hello
                 sql_mode:
          Create Function: CREATE FUNCTION `test`.`hello`(s CHAR(20)) »
                           RETURNS CHAR(50)
                           RETURN CONCAT('Hello, ',s,'!')
     character_set_client: latin1
     collation_connection: latin1_swedish_ci
       Database Collation: latin1_swedish_ci

`character_set_client' is the session value of the
`character_set_client' system variable when the routine was created.
`collation_connection' is the session value of the
`collation_connection' system variable when the routine was created.
`Database Collation' is the collation of the database with which the
routine is associated. These columns were added in MySQL 5.1.21.


File: manual.info,  Node: show-create-table,  Next: show-create-trigger,  Prev: show-create-procedure,  Up: show

12.5.5.11 `SHOW CREATE TABLE' Syntax
....................................

     SHOW CREATE TABLE TBL_NAME

Shows the `CREATE TABLE' statement that creates the given table. This
statement also works with views.

     mysql> SHOW CREATE TABLE t\G
     *************************** 1. row ***************************
            Table: t
     Create Table: CREATE TABLE t (
       id INT(11) default NULL auto_increment,
       s char(60) default NULL,
       PRIMARY KEY (id)
     ) ENGINE=MyISAM

`SHOW CREATE TABLE' quotes table and column names according to the
value of the `SQL_QUOTE_SHOW_CREATE' option. See *Note
server-session-variables::.


File: manual.info,  Node: show-create-trigger,  Next: show-create-view,  Prev: show-create-table,  Up: show

12.5.5.12 `SHOW CREATE TRIGGER' Syntax
......................................

     SHOW CREATE TRIGGER TRIGGER_NAME

This statement shows a `CREATE TRIGGER' statement that creates the
given trigger.

     mysql> SHOW CREATE TRIGGER ins_sum\G
     *************************** 1. row ***************************
                    Trigger: ins_sum
                   sql_mode:
     SQL Original Statement: CREATE DEFINER=`bob`@`localhost` TRIGGER ins_sum
                             BEFORE INSERT ON account
                             FOR EACH ROW SET @sum = @sum + NEW.amount
       character_set_client: latin1
       collation_connection: latin1_swedish_ci
         Database Collation: latin1_swedish_ci

This statement was added in MySQL 5.1.21.

You can also obtain information about trigger objects from
`INFORMATION_SCHEMA', which contains a `TRIGGERS' table. See *Note
triggers-table::.


File: manual.info,  Node: show-create-view,  Next: show-databases,  Prev: show-create-trigger,  Up: show

12.5.5.13 `SHOW CREATE VIEW' Syntax
...................................

     SHOW CREATE VIEW VIEW_NAME

This statement shows a `CREATE VIEW' statement that creates the given
view.

     mysql> SHOW CREATE VIEW v\G
     *************************** 1. row ***************************
                     View: v
              Create View: CREATE ALGORITHM=UNDEFINED
                           DEFINER=`bob`@`localhost`
                           SQL SECURITY DEFINER VIEW
                           `v` AS select 1 AS `a`,2 AS `b`
     character_set_client: latin1
     collation_connection: latin1_swedish_ci

`character_set_client' is the session value of the
`character_set_client' system variable when the routine was created.
`collation_connection' is the session value of the
`collation_connection' system variable when the routine was created.
These columns were added in MySQL 5.1.21.

Use of `SHOW CREATE VIEW' requires the `SHOW VIEW' privilege and the
`SELECT' privilege for the view in question.

You can also obtain information about view objects from
`INFORMATION_SCHEMA', which contains a `VIEWS' table. See *Note
views-table::.


File: manual.info,  Node: show-databases,  Next: show-engine,  Prev: show-create-view,  Up: show

12.5.5.14 `SHOW DATABASES' Syntax
.................................

     SHOW {DATABASES | SCHEMAS}
         [LIKE 'PATTERN' | WHERE EXPR]

`SHOW DATABASES' lists the databases on the MySQL server host. `SHOW
SCHEMAS' is a synonym for `SHOW DATABASES'. The `LIKE' clause, if
present, indicates which database names to match. The `WHERE' clause
can be given to select rows using more general conditions, as discussed
in *Note extended-show::.

You see only those databases for which you have some kind of privilege,
unless you have the global `SHOW DATABASES' privilege. You can also get
this list using the `mysqlshow' command.

If the server was started with the `--skip-show-database' option, you
cannot use this statement at all unless you have the `SHOW DATABASES'
privilege.

`SHOW SCHEMAS' can also be used.


File: manual.info,  Node: show-engine,  Next: show-engines,  Prev: show-databases,  Up: show

12.5.5.15 `SHOW ENGINE' Syntax
..............................

     SHOW ENGINE ENGINE_NAME {STATUS | MUTEX}

`SHOW ENGINE' displays operational information about a storage engine.
The following statements currently are supported:

     SHOW ENGINE INNODB STATUS
     SHOW ENGINE INNODB MUTEX
     SHOW ENGINE {NDB | NDBCLUSTER} STATUS

Older (and now deprecated) synonyms are `SHOW INNODB STATUS' for `SHOW
ENGINE INNODB STATUS' and `SHOW MUTEX STATUS' for `SHOW ENGINE INNODB
MUTEX'.

In MySQL 5.0, `SHOW ENGINE INNODB MUTEX' is invoked as `SHOW MUTEX
STATUS'. The latter statement displays similar information but in a
somewhat different output format.

`SHOW ENGINE BDB LOGS' formerly displayed status information about
`BDB' log files. As of MySQL 5.1.12, the `BDB' storage engine is not
supported, and this statement produces a warning.

`SHOW ENGINE INNODB STATUS' displays extensive information about the
state of the `InnoDB' storage engine.

The `InnoDB' Monitors provide additional information about `InnoDB'
processing. See *Note innodb-monitor::.

`SHOW ENGINE INNODB MUTEX' displays `InnoDB' mutex statistics. From
MySQL 5.1.2 to 5.1.14, the statement displays the following output
fields:

   * `Type'

     Always `InnoDB'.

   * `Name'

     The mutex name and the source file where it is implemented.
     Example: `&pool->mutex:mem0pool.c'

     The mutex name indicates its purpose. For example, the `log_sys'
     mutex is used by the `InnoDB' logging subsystem and indicates how
     intensive logging activity is. The `buf_pool' mutex protects the
     `InnoDB' buffer pool.

   * `Status'

     The mutex status. The fields contains several values:

        * `count' indicates how many times the mutex was requested.

        * `spin_waits' indicates how many times the spinlock had to run.

        * `spin_rounds' indicates the number of spinlock rounds.
          (`spin_rounds' divided by `spin_waits' provides the average
          round count.)

        * `os_waits' indicates the number of operating system waits.
          This occurs when the spinlock did not work (the mutex was not
          locked during the spinlock and it was necessary to yield to
          the operating system and wait).

        * `os_yields' indicates the number of times a the thread trying
          to lock a mutex gave up its timeslice and yielded to the
          operating system (on the presumption that allowing other
          threads to run will free the mutex so that it can be locked).

        * `os_wait_times' indicates the amount of time (in ms) spent in
          operating system waits, if the `timed_mutexes' system
          variable is 1 (`ON'). If `timed_mutexes' is 0 (`OFF'), timing
          is disabled, so `os_wait_times' is 0.  `timed_mutexes' is off
          by default.

From MySQL 5.1.15 on, the statement displays the following output
fields:

   * `Type'

     Always `InnoDB'.

   * `Name'

     The source file where the mutex is implemented, and the line
     number in the file where the mutex is created. The line number may
     change depending on your version of MySQL.

   * `Status'

     This field displays the same values as previously described
     (`count', `spin_waits', `spin_rounds', `os_waits', `os_yields',
     `os_wait_times'), but only if `UNIV_DEBUG' was defined at MySQL
     compilation time (for example, in `include/univ.h' in the `InnoDB'
     part of the MySQL source tree). If `UNIV_DEBUG' was not defined,
     the statement displays only the `os_waits' value. In the latter
     case (without `UNIV_DEBUG'), the information on which the output
     is based is insufficient to distinguish regular mutexes and
     mutexes that protect rw-locks (which allow multiple readers or a
     single writer).  Consequently, the output may appear to contain
     multiple rows for the same mutex.

Information from this statement can be used to diagnose system
problems. For example, large values of `spin_waits' and `spin_rounds'
may indicate scalability problems.

If the server has the `NDBCLUSTER' storage engine enabled, `SHOW ENGINE
NDB STATUS' displays cluster status information such as the number of
connected data nodes, the cluster connectstring, and cluster binlog
epochs, as well as counts of various Cluster API objects created by the
MySQL Server when connected to the cluster.  Sample output from this
statement is shown here:

     mysql> SHOW ENGINE NDB STATUS;
     +------------+-----------------------+--------------------------------------------------+
     | Type       | Name                  | Status                                           |
     +------------+-----------------------+--------------------------------------------------+
     | ndbcluster | connection            | cluster_node_id=7,
       connected_host=192.168.0.103, connected_port=1186, number_of_data_nodes=4,
       number_of_ready_data_nodes=3, connect_count=0                                         |
     | ndbcluster | NdbTransaction        | created=6, free=0, sizeof=212                    |
     | ndbcluster | NdbOperation          | created=8, free=8, sizeof=660                    |
     | ndbcluster | NdbIndexScanOperation | created=1, free=1, sizeof=744                    |
     | ndbcluster | NdbIndexOperation     | created=0, free=0, sizeof=664                    |
     | ndbcluster | NdbRecAttr            | created=1285, free=1285, sizeof=60               |
     | ndbcluster | NdbApiSignal          | created=16, free=16, sizeof=136                  |
     | ndbcluster | NdbLabel              | created=0, free=0, sizeof=196                    |
     | ndbcluster | NdbBranch             | created=0, free=0, sizeof=24                     |
     | ndbcluster | NdbSubroutine         | created=0, free=0, sizeof=68                     |
     | ndbcluster | NdbCall               | created=0, free=0, sizeof=16                     |
     | ndbcluster | NdbBlob               | created=1, free=1, sizeof=264                    |
     | ndbcluster | NdbReceiver           | created=4, free=0, sizeof=68                     |
     | ndbcluster | binlog                | latest_epoch=155467, latest_trans_epoch=148126,
       latest_received_binlog_epoch=0, latest_handled_binlog_epoch=0,
       latest_applied_binlog_epoch=0                                                         |
     +------------+-----------------------+--------------------------------------------------+

The rows with `connection' and `binlog' in the `Name' column were added
to the output of this statement in MySQL 5.1. The `Status' column in
each of these rows provides information about the MySQL server's
connection to the cluster and about the cluster binary log's status,
respectively. The `Status' information is in the form of
comma-delimited set of name/value pairs.

The `connection' row's `Status' column contains the name/value pairs
described in the following table:

*Name*                        *Value*
`cluster_node_id'             The node ID of the MySQL server in the
                              cluster
`connected_host'              The hostname or IP address of the cluster
                              management server to which the MySQL
                              server is connected
`connected_port'              The port used by the MySQL server to
                              connect to the management server
                              (`connected_host')
`number_of_data_nodes'        The number of data nodes configured for
                              the cluster (that is, the number of
                              `[ndbd]' sections in the cluster
                              `config.ini' file)
`number_of_ready_data_nodes'  The number of data nodes in the cluster
                              that are actually running
`connect_count'               The number of times this `mysqld' has
                              connected or reconnected to cluster data
                              nodes

The `binlog' row's `Status' column contains information relating to
MySQL Cluster Replication. The name/value pairs it contains are
described in the following table:

*Name*                        *Value*
`latest_epoch'                The most recent epoch most recently run on
                              this MySQL server (that is, the sequence
                              number of the most recent transaction run
                              on the server)
`latest_trans_epoch'          The most recent epoch processed by the
                              cluster's data nodes
`latest_received_binlog_epoch'The most recent epoch received by the
                              binlog thread
`latest_handled_binlog_epoch' The most recent epoch processed by the
                              binlog thread (for writing to the binlog)
`latest_applied_binlog_epoch' The most recent epoch actually written to
                              the binlog

See *Note mysql-cluster-replication::, for more information.

The remaining rows from the output of `SHOW ENGINE NDB STATUS' which
are most likely to prove useful in monitoring the cluster are listed
here by `Name':

   * `NdbTransaction': The number and size of `NdbTransaction' objects
     that have been created. An `NdbTransaction' is created each time a
     table schema operation (such as `CREATE TABLE' or `ALTER TABLE') is
     performed on an `NDB' table.

   * `NdbOperation': The number and size of `NdbOperation' objects that
     have been created.

   * `NdbIndexScanOperation': The number and size of
     `NdbIndexScanOperation' objects that have been created.

   * `NdbIndexOperation': The number and size of `NdbIndexOperation'
     objects that have been created.

   * `NdbRecAttr': The number and size of `NdbRecAttr' objects that
     have been created. In general, one of these is created each time a
     data manipulation statement is performed by an SQL node.

   * `NdbBlob': The number and size of `NdbBlob' objects that have been
     created.  An `NdbBlob' is created for each new operation involving
     a `BLOB' column in an `NDB' table.

   * `NdbReceiver': The number and size of any `NdbReceiver' object
     that have been created. The number in the `created' column is the
     same as the number of data nodes in the cluster to which the MySQL
     server has connected.

*Note*:

`SHOW ENGINE NDB STATUS' returns an empty result if no operations
involving `NDB' tables have been performed during the current session
by the MySQL client accessing the SQL node on which this statement is
run.

MySQL Enterprise

The `SHOW ENGINE ENGINE_NAME STATUS' statement provides valuable
information about the state of your server. For expert interpretation
of this information, subscribe to the MySQL Enterprise Monitor. For more
information see `advisors.html'.


File: manual.info,  Node: show-engines,  Next: show-errors,  Prev: show-engine,  Up: show

12.5.5.16 `SHOW ENGINES' Syntax
...............................

     SHOW [STORAGE] ENGINES

`SHOW ENGINES' displays status information about the server's storage
engines. This is particularly useful for checking whether a storage
engine is supported, or to see what the default engine is. `SHOW TABLE
TYPES' is a deprecated synonym.

     mysql> SHOW ENGINES\G
     *************************** 1. row ***************************
           Engine: MEMORY
          Support: YES
          Comment: Hash based, stored in memory, useful for temporary tables
     Transactions: NO
               XA: NO
       Savepoints: NO
     *************************** 2. row ***************************
           Engine: MyISAM
          Support: DEFAULT
          Comment: Default engine as of MySQL 3.23 with great performance
     Transactions: NO
               XA: NO
       Savepoints: NO
     *************************** 3. row ***************************
           Engine: InnoDB
          Support: YES
          Comment: Supports transactions, row-level locking, and foreign keys
     Transactions: YES
               XA: YES
       Savepoints: YES
     *************************** 4. row ***************************
           Engine: EXAMPLE
          Support: YES
          Comment: Example storage engine
     Transactions: NO
               XA: NO
       Savepoints: NO
     *************************** 5. row ***************************
           Engine: ARCHIVE
          Support: YES
          Comment: Archive storage engine
     Transactions: NO
               XA: NO
       Savepoints: NO
     *************************** 6. row ***************************
           Engine: CSV
          Support: YES
          Comment: CSV storage engine
     Transactions: NO
               XA: NO
       Savepoints: NO
     *************************** 7. row ***************************
           Engine: BLACKHOLE
          Support: YES
          Comment: /dev/null storage engine (anything you write »
                   to it disappears)
     Transactions: NO
               XA: NO
       Savepoints: NO
     *************************** 8. row ***************************
           Engine: FEDERATED
          Support: YES
          Comment: Federated MySQL storage engine
     Transactions: NO
               XA: NO
       Savepoints: NO
     *************************** 9. row ***************************
           Engine: MRG_MYISAM
          Support: YES
          Comment: Collection of identical MyISAM tables
     Transactions: NO
               XA: NO
       Savepoints: NO

The output from `SHOW ENGINES' may vary according to the MySQL version
used and other factors. The values shown in the `Support' column
indicate the server's level of support for the storage engine, as shown
here:

*Value*     *Meaning*
`YES'       The engine is supported and is active
`DEFAULT'   Like `YES', plus this is the default engine
`NO'        The engine is not supported
`DISABLED'  The engine is supported but has been disabled

A value of `NO' means that the server was compiled without support for
the engine, so it cannot be activated at runtime.

A value of `DISABLED' occurs either because the server was started with
an option that disables the engine, or because not all options required
to enable it were given. In the latter case, the error log file should
contain a reason indicating why the option is disabled. See *Note
error-log::.

You might also see `DISABLED' for a storage engine if the server was
compiled to support it, but was started with a `--skip-ENGINE_NAME'
option. For the `NDBCLUSTER' storage engine, `DISABLED' means the
server was compiled with support for MySQL Cluster, but was not started
with the `--ndbcluster' option.

All MySQL servers support `MyISAM' tables, because `MyISAM' is the
default storage engine.  It is not possible to disable `MyISAM'.

The `Transactions', `XA', and `Savepoints' columns were added in MySQL
5.1.2.  They indicate whether the storage engine supports transactions,
XA transactions, and savepoints, respectively.


File: manual.info,  Node: show-errors,  Next: show-events,  Prev: show-engines,  Up: show

12.5.5.17 `SHOW ERRORS' Syntax
..............................

     SHOW ERRORS [LIMIT [OFFSET,] ROW_COUNT]
     SHOW COUNT(*) ERRORS

This statement is similar to `SHOW WARNINGS', except that instead of
displaying errors, warnings, and notes, it displays only errors.

The `LIMIT' clause has the same syntax as for the `SELECT' statement.
See *Note select::.

The `SHOW COUNT(*) ERRORS' statement displays the number of errors. You
can also retrieve this number from the `error_count' variable:

     SHOW COUNT(*) ERRORS;
     SELECT @@error_count;

For more information, see *Note show-warnings::.


File: manual.info,  Node: show-events,  Next: show-grants,  Prev: show-errors,  Up: show

12.5.5.18 `SHOW EVENTS'
.......................

     SHOW EVENTS [FROM SCHEMA_NAME]
         [LIKE 'PATTERN' | WHERE EXPR]

In its simplest form, `SHOW EVENTS' lists all of the events in the
current schema:

     mysql> SELECT CURRENT_USER(), SCHEMA();
     +----------------+----------+
     | CURRENT_USER() | SCHEMA() |
     +----------------+----------+
     | jon@ghidora    | myschema |
     +----------------+----------+
     1 row in set (0.00 sec)

     mysql> SHOW EVENTS\G
     *************************** 1. row ***************************
                       Db: myschema
                     Name: e_daily
                  Definer: jon@ghidora
                Time zone: SYSTEM
                     Type: RECURRING
               Execute at: NULL
           Interval value: 10
           Interval field: INTERVAL_SECOND
                   Starts: 2006-02-09 10:41:23
                     Ends: 0000-00-00 00:00:00
                   Status: ENABLED
               Originator: 0
     character_set_client: latin1
     collation_connection: latin1_swedish_ci
       Database Collation: latin1_swedish_ci

The `LIKE' clause, if present, indicates which event names to match. The
`WHERE' clause can be given to select rows using more general
conditions, as discussed in *Note extended-show::.

The columns in the output of `SHOW EVENTS' -- which are similar to, but
not identical to the columns in the `INFORMATION_SCHEMA.EVENTS' table
-- are shown here:

   * `Db': The schema (database) on which the event is defined.

   * `Name': The name of the event.

   * `Time zone': The time zone in effect when schedule for the event
     was last modified. If the event's schedule has not been modified
     since the event was created, then this is the time zone that was
     in effect at the event's creation. The default value is `SYSTEM'.

     This column was added in MySQL 5.1.17. See *Note news-5-1-17::,
     for important information if you are using the Event Scheduler and
     are upgrading from MySQL 5.1.16 (or earlier) to MySQL 5.1.17 (or
     later).

   * `Definer': The user account (`USERNAME@HOSTNAME') which created
     the event.

   * `Type': One of the two values `ONE TIME' (transient) or
     `RECURRING'.

   * `Execute At': The date and time when a transient event is set to
     execute. Shown as a `DATETIME' value.

     For a recurring event, the value of this column is always `NULL'.

   * `Interval Value': For a recurring event, the number of intervals
     to wait between event executions.

     For a transient event, the value of this column is always `NULL'.

   * `Interval Field': The time units used for the interval which a
     recurring event waits before repeating.

     For a transient event, the value of this column is always `NULL'.

   * `Starts': The start date and time for a recurring event. This is
     displayed as a `DATETIME' value, and is empty if no start date and
     time are defined for the event. (Prior to MySQL 5.1.8, it
     defaulted to `'0000-00-00 00:00:00'' in such cases.)

     For a transient event, the value of this column is always `NULL'.

   * `Ends': The end date and time for a recurring event. This is
     displayed as a `DATETIME' value, and defaults to `'0000-00-00
     00:00:00'' if no end date and time is defined for the event.

     For a transient event, the value of this column is always `NULL'.

   * `Status': The event status. One of `ENABLED', `DISABLED', or
     `SLAVESIDE_DISABLED'.

     `SLAVESIDE_DISABLED' was added in MySQL 5.1.18. This value
     indicates that the creation of the event occurred on another MySQL
     server acting as a replication master and replicated to the
     current MySQL server which is acting as a slave, but the event is
     not presently being executed on the slave.

   * `Originator': The server ID of the MySQL server on which the event
     was created. Defaults to 0. This column was added in MySQL 5.1.18.

   * `character_set_client' is the session value of the
     `character_set_client' system variable when the routine was
     created.  `collation_connection' is the session value of the
     `collation_connection' system variable when the routine was
     created. `Database Collation' is the collation of the database with
     which the routine is associated. These columns were added in MySQL
     5.1.21.

For more information about `SLAVE_DISABLED' and the `Originator'
column, see *Note replication-features-invoked::.

Note that the action statement is not shown in the output of `SHOW
EVENTS'.

Prior to MySQL 5.1.17, the values displayed for `Starts' and `Ends'
(other than `'0000-00-00 00:00:00'') were shown using Universal Time
(Bug#16420 (http://bugs.mysql.com/16420)). Beginning with MySQL 5.1.17,
these times are all given in terms of local time as determined by the
MySQL server's `time_zone' setting. See also *Note events-table::.

To see events for a different schema, you can use the `FROM' clause.
For example, if the `test' schema had been selected in the preceding
example, you could view events defined on `myschema' using the
following statement:

     SHOW EVENTS FROM myschema;

You can filter the list returned by this statement on the event name
using `LIKE' plus a pattern.

This statement was added in MySQL 5.1.6.

See also *Note events-table::.

*Note*:

In MySQL 5.1.11 and earlier, `SHOW EVENTS' displayed only those events
for which the current user was the definer, and the `SHOW FULL EVENTS'
statement was used for viewing events defined by all users on a given
schema. `SHOW FULL EVENTS' was removed in MySQL 5.1.12.


File: manual.info,  Node: show-grants,  Next: show-index,  Prev: show-events,  Up: show

12.5.5.19 `SHOW GRANTS' Syntax
..............................

     SHOW GRANTS [FOR USER]

This statement lists the `GRANT' statement or statements that must be
issued to duplicate the privileges that are granted to a MySQL user
account. The account is named using the same format as for the `GRANT'
statement; for example, `'jeffrey'@'localhost''. If you specify only
the username part of the account name, a hostname part of `'%'' is
used. For additional information about specifying account names, see
*Note grant::.

     mysql> SHOW GRANTS FOR 'root'@'localhost';
     +---------------------------------------------------------------------+
     | Grants for root@localhost                                           |
     +---------------------------------------------------------------------+
     | GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' WITH GRANT OPTION |
     +---------------------------------------------------------------------+

To list the privileges granted to the account that you are using to
connect to the server, you can use any of the following statements:

     SHOW GRANTS;
     SHOW GRANTS FOR CURRENT_USER;
     SHOW GRANTS FOR CURRENT_USER();

As of MySQL 5.1.12, if `SHOW GRANTS FOR CURRENT_USER' (or any of the
equivalent syntaxes) is used in `DEFINER' context, such as within a
stored procedure that is defined with `SQL SECURITY DEFINER'), the
grants displayed are those of the definer and not the invoker.

`SHOW GRANTS' displays only the privileges granted explicitly to the
named account. Other privileges might be available to the account, but
they are not displayed. For example, if an anonymous account exists,
the named account might be able to use its privileges, but `SHOW
GRANTS' will not display them.


File: manual.info,  Node: show-index,  Next: show-innodb-status,  Prev: show-grants,  Up: show

12.5.5.20 `SHOW INDEX' Syntax
.............................

     SHOW INDEX FROM TBL_NAME [FROM DB_NAME]

`SHOW INDEX' returns table index information.  The format resembles
that of the `SQLStatistics' call in ODBC.

`SHOW INDEX' returns the following fields:

   * `Table'

     The name of the table.

   * `Non_unique'

     0 if the index cannot contain duplicates, 1 if it can.

   * `Key_name'

     The name of the index.

   * `Seq_in_index'

     The column sequence number in the index, starting with 1.

   * `Column_name'

     The column name.

   * `Collation'

     How the column is sorted in the index. In MySQL, this can have
     values ``A'' (Ascending) or `NULL' (Not sorted).

   * `Cardinality'

     An estimate of the number of unique values in the index.  This is
     updated by running `ANALYZE TABLE' or `myisamchk -a'.
     `Cardinality' is counted based on statistics stored as integers,
     so the value is not necessarily exact even for small tables. The
     higher the cardinality, the greater the chance that MySQL uses the
     index when doing joins.

   * `Sub_part'

     The number of indexed characters if the column is only partly
     indexed, `NULL' if the entire column is indexed.

   * `Packed'

     Indicates how the key is packed. `NULL' if it is not.

   * `Null'

     Contains `YES' if the column may contain `NULL'. If not, the
     column contains `NO'.

     Contains `YES' if the column may contain `NULL' values and `''' if
     not.

   * `Index_type'

     The index method used (`BTREE', `FULLTEXT', `HASH', `RTREE').

   * `Comment'

     Various remarks.

You can use DB_NAME.TBL_NAME as an alternative to the `TBL_NAME FROM
DB_NAME' syntax. These two statements are equivalent:

     SHOW INDEX FROM mytable FROM mydb;
     SHOW INDEX FROM mydb.mytable;

`SHOW KEYS' is a synonym for `SHOW INDEX'. You can also list a table's
indexes with the `mysqlshow -k DB_NAME TBL_NAME' command.


File: manual.info,  Node: show-innodb-status,  Next: show-master-status,  Prev: show-index,  Up: show

12.5.5.21 `SHOW INNODB STATUS' Syntax
.....................................

     SHOW INNODB STATUS

In MySQL 5.1, this is a deprecated synonym for `SHOW ENGINE INNODB
STATUS'. See *Note show-engine::.


File: manual.info,  Node: show-master-status,  Next: show-open-tables,  Prev: show-innodb-status,  Up: show

12.5.5.22 `SHOW MASTER STATUS' Syntax
.....................................

     SHOW MASTER STATUS

Provides status information about the binary log files of the master.
Example:

     mysql> SHOW MASTER STATUS;
     +---------------+----------+--------------+------------------+
     | File          | Position | Binlog_Do_DB | Binlog_Ignore_DB |
     +---------------+----------+--------------+------------------+
     | mysql-bin.003 | 73       | test         | manual,mysql     |
     +---------------+----------+--------------+------------------+


File: manual.info,  Node: show-open-tables,  Next: show-plugins,  Prev: show-master-status,  Up: show

12.5.5.23 `SHOW OPEN TABLES' Syntax
...................................

     SHOW OPEN TABLES [FROM DB_NAME]
         [LIKE 'PATTERN' | WHERE EXPR]

`SHOW OPEN TABLES' lists the non-`TEMPORARY' tables that are currently
open in the table cache. See *Note table-cache::. The `WHERE' clause
can be given to select rows using more general conditions, as discussed
in *Note extended-show::.

The `FROM' and `LIKE' clauses may be used beginning with MySQL 5.1.24.
The `LIKE' clause, if present, indicates which table names to match. The
`FROM' clause, if present, restricts the tables shown to those present
in the DB_NAME database.

`SHOW OPEN TABLES' returns the following columns:

   * `Database'

     The database containing the table.

   * `Table'

     The table name.

   * `In_use'

     The number of table locks or lock requests there are for the
     table. For example, if one client acquires a lock for a table
     using `LOCK TABLE t1 WRITE', `In_use' will be 1. If another client
     issues `LOCK TABLE t1 WRITE' while the table remains locked, the
     client will block waiting for the lock, but the lock request
     causes `In_use' to be 2. If the count is zero, the table is open
     but not currently being used.

   * `Name_locked'

     Whether the table name is locked. Name locking is used for
     operations such as dropping or renaming tables.


File: manual.info,  Node: show-plugins,  Next: show-privileges,  Prev: show-open-tables,  Up: show

12.5.5.24 `SHOW PLUGINS' Syntax
...............................

     SHOW PLUGINS

`SHOW PLUGINS' displays information about known plugins.

     mysql> SHOW PLUGINS;
     +------------+--------+----------------+---------+
     | Name       | Status | Type           | Library |
     +------------+--------+----------------+---------+
     | MEMORY     | ACTIVE | STORAGE ENGINE | NULL    |
     | MyISAM     | ACTIVE | STORAGE ENGINE | NULL    |
     | InnoDB     | ACTIVE | STORAGE ENGINE | NULL    |
     | ARCHIVE    | ACTIVE | STORAGE ENGINE | NULL    |
     | CSV        | ACTIVE | STORAGE ENGINE | NULL    |
     | BLACKHOLE  | ACTIVE | STORAGE ENGINE | NULL    |
     | FEDERATED  | ACTIVE | STORAGE ENGINE | NULL    |
     | MRG_MYISAM | ACTIVE | STORAGE ENGINE | NULL    |
     +------------+--------+----------------+---------+

`SHOW PLUGIN' was added in MySQL 5.1.5 and renamed to `SHOW PLUGINS' in
5.1.9. (As of 5.1.9, `SHOW PLUGIN' is deprecated and generates a
warning.)


File: manual.info,  Node: show-privileges,  Next: show-procedure-code,  Prev: show-plugins,  Up: show

12.5.5.25 `SHOW PRIVILEGES' Syntax
..................................

     SHOW PRIVILEGES

`SHOW PRIVILEGES' shows the list of system privileges that the MySQL
server supports. The exact list of privileges depends on the version of
your server.

     mysql> SHOW PRIVILEGES\G
     *************************** 1. row ***************************
     Privilege: Alter
     Context: Tables
     Comment: To alter the table
     *************************** 2. row ***************************
     Privilege: Alter routine
     Context: Functions,Procedures
     Comment: To alter or drop stored functions/procedures
     *************************** 3. row ***************************
     Privilege: Create
     Context: Databases,Tables,Indexes
     Comment: To create new databases and tables
     *************************** 4. row ***************************
     Privilege: Create routine
     Context: Functions,Procedures
     Comment: To use CREATE FUNCTION/PROCEDURE
     *************************** 5. row ***************************
     Privilege: Create temporary tables
     Context: Databases
     Comment: To use CREATE TEMPORARY TABLE
     ...

Privileges belonging to a specific user are displayed by the `SHOW
GRANTS' statement. See *Note show-grants::, for more information.


File: manual.info,  Node: show-procedure-code,  Next: show-procedure-status,  Prev: show-privileges,  Up: show

12.5.5.26 `SHOW PROCEDURE CODE' and `SHOW FUNCTION CODE' Syntax
...............................................................

     SHOW {PROCEDURE | FUNCTION} CODE SP_NAME

These statements are MySQL extensions that are available only for
servers that have been built with debugging support. They display a
representation of the internal implementation of the named routine. The
statements require that you be the owner of the routine or have
`SELECT' access to the `mysql.proc' table.

If the named routine is available, each statement produces a result
set. Each row in the result set corresponds to one `instruction' in the
routine. The first column is `Pos', which is an ordinal number beginning
with 0. The second column is `Instruction', which contains an SQL
statement (usually changed from the original source), or a directive
which has meaning only to the stored-routine handler.

     mysql> DELIMITER //
     mysql> CREATE PROCEDURE p1 ()
         -> BEGIN
         ->   DECLARE fanta INT DEFAULT 55;
         ->   DROP TABLE t2;
         ->   LOOP
         ->     INSERT INTO t3 VALUES (fanta);
         ->     END LOOP;
         ->   END//
     Query OK, 0 rows affected (0.00 sec)

     mysql> SHOW PROCEDURE CODE p1//
     +-----+----------------------------------------+
     | Pos | Instruction                            |
     +-----+----------------------------------------+
     |   0 | set fanta@0 55                         |
     |   1 | stmt 9 "DROP TABLE t2"                 |
     |   2 | stmt 5 "INSERT INTO t3 VALUES (fanta)" |
     |   3 | jump 2                                 |
     +-----+----------------------------------------+
     4 rows in set (0.00 sec)

In this example, the non-executable `BEGIN' and `END' statements have
disappeared, and for the `DECLARE VARIABLE_NAME' statement, only the
executable part appears (the part where the default is assigned). For
each statement that is taken from source, there is a code word `stmt'
followed by a type (9 means `DROP', 5 means `INSERT', and so on). The
final row contains an instruction `jump 2', meaning `GOTO instruction
#2'.

These statements were added in MySQL 5.1.3.


File: manual.info,  Node: show-procedure-status,  Next: show-processlist,  Prev: show-procedure-code,  Up: show

12.5.5.27 `SHOW PROCEDURE STATUS' and `SHOW FUNCTION STATUS' Syntax
...................................................................

     SHOW {PROCEDURE | FUNCTION} STATUS
         [LIKE 'PATTERN' | WHERE EXPR]

These statements are MySQL extensions. They return characteristics of
routines, such as the database, name, type, creator, creation and
modification dates, and character set information. The `LIKE' clause,
if present, indicates which procedure or function names to match. The
`WHERE' clause can be given to select rows using more general
conditions, as discussed in *Note extended-show::.

     mysql> SHOW FUNCTION STATUS LIKE 'hello'\G
     *************************** 1. row ***************************
                       Db: test
                     Name: hello
                     Type: FUNCTION
                  Definer: testuser@localhost
                 Modified: 2004-08-03 15:29:37
                  Created: 2004-08-03 15:29:37
            Security_type: DEFINER
                  Comment:
     character_set_client: latin1
     collation_connection: latin1_swedish_ci
       Database Collation: latin1_swedish_ci

`character_set_client' is the session value of the
`character_set_client' system variable when the routine was created.
`collation_connection' is the session value of the
`collation_connection' system variable when the routine was created.
`Database Collation' is the collation of the database with which the
routine is associated. These columns were added in MySQL 5.1.21.

You can also get information about stored routines from the `ROUTINES'
table in `INFORMATION_SCHEMA'. See *Note routines-table::.


File: manual.info,  Node: show-processlist,  Next: show-scheduler-status,  Prev: show-procedure-status,  Up: show

12.5.5.28 `SHOW PROCESSLIST' Syntax
...................................

     SHOW [FULL] PROCESSLIST

`SHOW PROCESSLIST' shows you which threads are running. You can also
get this information from the `INFORMATION_SCHEMA' `PROCESSLIST' table
or the `mysqladmin processlist' command. If you have the `PROCESS'
privilege, you can see all threads.  Otherwise, you can see only your
own threads (that is, threads associated with the MySQL account that
you are using). If you do not use the `FULL' keyword, only the first 100
characters of each statement are shown in the `Info' field.

MySQL Enterprise

Subscribers to MySQL Enterprise Monitor receive instant notification
and expert advice on resolution when there are too many concurrent
processes. For more information, see `advisors.html'.

This statement is very useful if you get the `too many connections'
error message and want to find out what is going on. MySQL reserves one
extra connection to be used by accounts that have the `SUPER'
privilege, to ensure that administrators should always be able to
connect and check the system (assuming that you are not giving this
privilege to all your users).

Threads can be killed with the `KILL' statement. See *Note kill::.

Here is an example of what `SHOW PROCESSLIST' output looks like:

     mysql> SHOW FULL PROCESSLIST\G
     *************************** 1. row ***************************
     Id: 1
     User: system user
     Host:
     db: NULL
     Command: Connect
     Time: 1030455
     State: Waiting for master to send event
     Info: NULL
     *************************** 2. row ***************************
     Id: 2
     User: system user
     Host:
     db: NULL
     Command: Connect
     Time: 1004
     State: Has read all relay log; waiting for the slave
            I/O thread to update it
     Info: NULL
     *************************** 3. row ***************************
     Id: 3112
     User: replikator
     Host: artemis:2204
     db: NULL
     Command: Binlog Dump
     Time: 2144
     State: Has sent all binlog to slave; waiting for binlog to be updated
     Info: NULL
     *************************** 4. row ***************************
     Id: 3113
     User: replikator
     Host: iconnect2:45781
     db: NULL
     Command: Binlog Dump
     Time: 2086
     State: Has sent all binlog to slave; waiting for binlog to be updated
     Info: NULL
     *************************** 5. row ***************************
     Id: 3123
     User: stefan
     Host: localhost
     db: apollon
     Command: Query
     Time: 0
     State: NULL
     Info: SHOW FULL PROCESSLIST
     5 rows in set (0.00 sec)

The columns have the following meaning:

   * `Id'

     The connection identifier.

   * `User'

     The MySQL user who issued the statement. If this is `system user',
     it refers to a non-client thread spawned by the server to handle
     tasks internally.  This could be the I/O or SQL thread used on
     replication slaves or a delayed-row handler. `unauthenticated
     user' refers to a thread that has become associated with a client
     connection but for which authentication of the client user has not
     yet been done.  `event_scheduler' refers to the thread that
     monitors scheduled events. For `system user' or `event_scheduler',
     there is no host specified in the `Host' column.

   * `Host'

     The hostname of the client issuing the statement (except for
     `system user' where there is no host).  `SHOW PROCESSLIST' reports
     the hostname for TCP/IP connections in `HOST_NAME:CLIENT_PORT'
     format to make it easier to determine which client is doing what.

   * `db'

     The default database, if one is selected, otherwise `NULL'.

   * `Command'

     The type of command the thread is executing. Descriptions for
     thread commands can be found at *Note thread-information::. The
     value of this column corresponds to the `COM_XXX' commands of the
     client/server protocol. See *Note server-status-variables::

   * `Time'

     The time in seconds that the thread has been in its current state.

   * `State'

     An action, event, or state that indicates what the thread is
     doing. Descriptions for `State' values can be found at *Note
     thread-information::.

     Most states correspond to very quick operations. If a thread stays
     in a given state for many seconds, there might be a problem that
     needs to be investigated.

     For the `SHOW PROCESSLIST' statement, the value of `State' is
     `NULL'.

   * `Info'

     The statement that the thread is executing, or `NULL' if it is not
     executing any statement. The statment might be the one sent to the
     server, or an innermost statement if the statement executes other
     statements. For example, if a `CALL p1()' statement executes a
     stored procedure `p1()', and the procedure is executing a `SELECT'
     statement, the `Info' value shows the `SELECT' statement.


File: manual.info,  Node: show-scheduler-status,  Next: show-slave-hosts,  Prev: show-processlist,  Up: show

12.5.5.29 `SHOW SCHEDULER STATUS' Syntax
........................................

     SHOW SCHEDULER STATUS

This statement provides debugging information regarding the Event
Scheduler's state. It is supported only in `-debug' builds of MySQL
5.1.11, and was removed in 5.1.12 and subsequent releases.

Sample output is shown here:

     +--------------------------------+---------------------+
     | Name                           | Value               |
     +--------------------------------+---------------------+
     | scheduler state                | INITIALIZED         |
     | thread_id                      | NULL                |
     | scheduler last locked at       | init_scheduler::313 |
     | scheduler last unlocked at     | init_scheduler::318 |
     | scheduler waiting on condition | 0                   |
     | scheduler workers count        | 0                   |
     | scheduler executed events      | 0                   |
     | scheduler data locked          | 0                   |
     | queue element count            | 1                   |
     | queue data locked              | 0                   |
     | queue data attempting lock     | 0                   |
     | queue last locked at           | create_event::218   |
     | queue last unlocked at         | create_event::222   |
     | queue last attempted lock at   | ::0                 |
     | queue waiting on condition     | 0                   |
     | next activation at             |    0-00-00 00:00:00 |
     +--------------------------------+---------------------+

In MySQL 5.1.12 and later, this information can be obtained using
`mysqladmin debug'. (See *Note mysqladmin::.) For more information about
obtaining Event Scheduler status information, see *Note
events-status-info::.


File: manual.info,  Node: show-slave-hosts,  Next: show-slave-status,  Prev: show-scheduler-status,  Up: show

12.5.5.30 `SHOW SLAVE HOSTS' Syntax
...................................

     SHOW SLAVE HOSTS

Displays a list of replication slaves currently registered with the
master. Only slaves started with the `--report-host=SLAVE_NAME' option
are visible in this list.

The list is displayed on any server (not just the master server). The
output looks like this:

     mysql> SHOW SLAVE HOSTS;
     +------------+-----------+------+-----------+
     | Server_id  | Host      | Port | Master_id |
     +------------+-----------+------+-----------+
     |  192168010 | iconnect2 | 3306 | 192168011 |
     | 1921680101 | athena    | 3306 | 192168011 |
     +------------+-----------+------+-----------+

   * `Server_id': The unique server ID of the slave server, as
     configured in the server's option file, or on the command line with
     `--server-id=VALUE'.

   * `Host': The host name of the slave server, as configured in the
     server's option file, or on the command line with
     `--report-host=VALUE'.  Note that this can differ from the machine
     name as configured in the operating system.

   * `Port': The port the slave server is listening on.

   * `Master_id': The unique server ID of the master server that the
     slave server is replicating from.

Some MySQL versions report another variable, `Rpl_recovery_rank'. This
variable was never used, and was eventually removed.


File: manual.info,  Node: show-slave-status,  Next: show-status,  Prev: show-slave-hosts,  Up: show

12.5.5.31 `SHOW SLAVE STATUS' Syntax
....................................

     SHOW SLAVE STATUS

This statement provides status information on essential parameters of
the slave threads. If you issue this statement using the `mysql'
client, you can use a `\G' statement terminator rather than a semicolon
to obtain a more readable vertical layout:

     mysql> SHOW SLAVE STATUS\G
     *************************** 1. row ***************************
                    Slave_IO_State: Waiting for master to send event
                       Master_Host: localhost
                       Master_User: root
                       Master_Port: 3306
                     Connect_Retry: 3
                   Master_Log_File: gbichot-bin.005
               Read_Master_Log_Pos: 79
                    Relay_Log_File: gbichot-relay-bin.005
                     Relay_Log_Pos: 548
             Relay_Master_Log_File: gbichot-bin.005
                  Slave_IO_Running: Yes
                 Slave_SQL_Running: Yes
                   Replicate_Do_DB:
               Replicate_Ignore_DB:
                        Last_Errno: 0
                        Last_Error:
                      Skip_Counter: 0
               Exec_Master_Log_Pos: 79
                   Relay_Log_Space: 552
                   Until_Condition: None
                    Until_Log_File:
                     Until_Log_Pos: 0
                Master_SSL_Allowed: No
                Master_SSL_CA_File:
                Master_SSL_CA_Path:
                   Master_SSL_Cert:
                 Master_SSL_Cipher:
                    Master_SSL_Key:
             Seconds_Behind_Master: 8
     Master_SSL_Verify_Server_Cert: No
                     Last_IO_Errno: 0
                     Last_IO_Error:
                    Last_SQL_Errno: 0
                    Last_SQL_Error:

`SHOW SLAVE STATUS' returns the following fields:

   * `Slave_IO_State'

     A copy of the `State' field of the output of `SHOW PROCESSLIST'
     for the slave I/O thread. This tells you what the thread is doing:
     trying to connect to the master, waiting for events from the
     master, reconnecting to the master, and so on. Possible states are
     listed in *Note replication-implementation-details::. It is
     necessary to check this field for older versions of MySQL which
     allowed the thread to continue running while unsuccessfully trying
     to connect to the master. If it is running, there is no problem;
     if it is not, you can find the error in the `Last_Error' field
     (described below).

   * `Master_Host'

     The current master host.

   * `Master_User'

     The current user used to connect to the master.

   * `Master_Port'

     The current master port.

   * `Connect_Retry'

     The number of seconds between connect retries (default 60).  This
     may be set with the `CHANGE MASTER TO' statement or
     `--master-connect-retry' option.

   * `Master_Log_File'

     The name of the master binary log file from which the I/O thread
     is currently reading.

   * `Read_Master_Log_Pos'

     The position up to which the I/O thread has read in the current
     master binary log.

   * `Relay_Log_File'

     The name of the relay log file from which the SQL thread is
     currently reading and executing.

   * `Relay_Log_Pos'

     The position up to which the SQL thread has read and executed in
     the current relay log.

   * `Relay_Master_Log_File'

     The name of the master binary log file containing the most recent
     event executed by the SQL thread.

   * `Slave_IO_Running'

     Whether the I/O thread is started and has connected successfully
     to the master. For older versions of MySQL (prior to 4.1.14 and
     5.0.12) `Slave_IO_Running' is `YES' if the I/O thread is started,
     even if the slave hasn't connected to the master yet.

   * `Slave_SQL_Running'

     Whether the SQL thread is started.

   * `Replicate_Do_DB', `Replicate_Ignore_DB'

     The lists of databases that were specified with the
     `--replicate-do-db' and `--replicate-ignore-db' options, if any.

   * `Replicate_Do_Table', `Replicate_Ignore_Table',
     `Replicate_Wild_Do_Table', `Replicate_Wild_Ignore_Table'

     The lists of tables that were specified with the
     `--replicate-do-table', `--replicate-ignore-table',
     `--replicate-wild-do-table', and `--replicate-wild-ignore_table'
     options, if any.

   * `Last_Errno', `Last_Error'

     As of MySQL 5.1.20, these columns are aliases for `Last_SQL_Errno'
     and `Last_SQL_Error'. Before 5.1.20, they indicate the error
     number and error message returned by the most recently executed
     statement. An error number of 0 and message of the empty string
     mean `no error.' If the `Last_Error' value is not empty, it also
     appears as a message in the slave's error log.

   * `Skip_Counter'

     The most recently used value for `SQL_SLAVE_SKIP_COUNTER'.

   * `Exec_Master_Log_Pos'

     The position of the last event executed by the SQL thread from the
     master's binary log (`Relay_Master_Log_File').
     (`Relay_Master_Log_File', `Exec_Master_Log_Pos') in the master's
     binary log corresponds to (`Relay_Log_File', `Relay_Log_Pos') in
     the relay log.

   * `Relay_Log_Space'

     The total combined size of all existing relay logs.

   * `Until_Condition', `Until_Log_File', `Until_Log_Pos'

     The values specified in the `UNTIL' clause of the `START SLAVE'
     statement.

     `Until_Condition' has these values:

        * `None' if no `UNTIL' clause was specified

        * `Master' if the slave is reading until a given position in
          the master's binary logs

        * `Relay' if the slave is reading until a given position in its
          relay logs

     `Until_Log_File' and `Until_Log_Pos' indicate the log filename and
     position values that define the point at which the SQL thread
     stops executing.

   * `Master_SSL_Allowed', `Master_SSL_CA_File', `Master_SSL_CA_Path',
     `Master_SSL_Cert', `Master_SSL_Cipher', `Master_SSL_Key'

     These fields show the SSL parameters used by the slave to connect
     to the master, if any.

     `Master_SSL_Allowed' has these values:

        * `Yes' if an SSL connection to the master is permitted

        * `No' if an SSL connection to the master is not permitted

        * `Ignored' if an SSL connection is permitted but the slave
          server does not have SSL support enabled

     The values of the other SSL-related fields correspond to the
     values of the `MASTER_SSL_CA', `MASTER_SSL_CAPATH',
     `MASTER_SSL_CERT', `MASTER_SSL_CIPHER', `MASTER_SSL_KEY', and
     `MASTER_SSL_VERIFY_SERVER_CERT' options to the `CHANGE MASTER'
     statement. See *Note change-master-to::.
     `MASTER_SSL_VERIFY_SERVER_CERT' was added in MySQL 5.1.18.

   * `Seconds_Behind_Master'

     This field is an indication of how `late' the slave is:

        * When the slave SQL thread is actively running (processing
          updates), this field is the number of seconds that have
          elapsed since the timestamp of the most recent event on the
          master executed by that thread.

        * When the SQL thread has caught up to the slave I/O thread and
          goes idle waiting for more events from the I/O thread, this
          field is zero.

     In essence, this field measures the time difference in seconds
     between the slave SQL thread and the slave I/O thread.

     If the network connection between master and slave is fast, the
     slave I/O thread is very close to the master, so this field is a
     good approximation of how late the slave SQL thread is compared to
     the master. If the network is slow, this is _not_ a good
     approximation; the slave SQL thread may quite often be caught up
     with the slow-reading slave I/O thread, so `Seconds_Behind_Master'
     often shows a value of 0, even if the I/O thread is late compared
     to the master.  In other words, _this column is useful only for
     fast networks_.

     This time difference computation works even though the master and
     slave do not have identical clocks (the clock difference is
     computed when the slave I/O thread starts, and assumed to remain
     constant from then on).  `Seconds_Behind_Master' is `NULL' (which
     means `unknown') if the slave SQL thread is not running, or if the
     slave I/O thread is not running or not connected to master. For
     example if the slave I/O thread is sleeping for the number of
     seconds given by the `CHANGE MASTER TO' statement or
     `--master-connect-retry' option (default 60) before reconnecting,
     `NULL' is shown, as the slave cannot know what the master is doing,
     and so cannot say reliably how late it is.

     This field has one limitation. The timestamp is preserved through
     replication, which means that, if a master M1 is itself a slave of
     M0, any event from M1's binlog which originates in replicating an
     event from M0's binlog has the timestamp of that event. This
     enables MySQL to replicate `TIMESTAMP' successfully. However, the
     drawback for `Seconds_Behind_Master' is that if M1 also receives
     direct updates from clients, the value randomly deviates, because
     sometimes the last M1's event is from M0 and sometimes it is the
     most recent timestamp from a direct update.

   * `Last_IO_Errno', `Last_IO_Error'

     The error number and error message of the last error that caused
     the I/O thread to stop. An error number of 0 and message of the
     empty string mean `no error.' If the `Last_IO_Error' value is not
     empty, it also appears as a message in the slave's error log. These
     columns were added in MySQL 5.1.20.

   * `Last_SQL_Errno', `Last_SQL_Error'

     The error number and error message of the last error that caused
     the SQL thread to stop. An error number of 0 and message of the
     empty string mean `no error.' If the `Last_IO_Error' value is not
     empty, it also appears as a message in the slave's error log. These
     columns were added in MySQL 5.1.20.

     Example:

          Last_SQL_Errno: 1051
          Last_SQL_Error: error 'Unknown table 'z'' on query 'drop table z'

     The message indicates that the table `z' existed on the master and
     was dropped there, but it did not exist on the slave, so `DROP
     TABLE' failed on the slave. (This might occur, for example, if you
     forget to copy the table to the slave when setting up replication.)


File: manual.info,  Node: show-status,  Next: show-table-status,  Prev: show-slave-status,  Up: show

12.5.5.32 `SHOW STATUS' Syntax
..............................

     SHOW [GLOBAL | SESSION] STATUS
         [LIKE 'PATTERN' | WHERE EXPR]

`SHOW STATUS' provides server status information. This information also
can be obtained using the `mysqladmin extended-status' command. The
`LIKE' clause, if present, indicates which variable names to match. The
`WHERE' clause can be given to select rows using more general
conditions, as discussed in *Note extended-show::.

Partial output is shown here. The list of names and values may be
different for your server. The meaning of each variable is given in
*Note server-status-variables::.

     mysql> SHOW STATUS;
     +--------------------------+------------+
     | Variable_name            | Value      |
     +--------------------------+------------+
     | Aborted_clients          | 0          |
     | Aborted_connects         | 0          |
     | Bytes_received           | 155372598  |
     | Bytes_sent               | 1176560426 |
     | Connections              | 30023      |
     | Created_tmp_disk_tables  | 0          |
     | Created_tmp_tables       | 8340       |
     | Created_tmp_files        | 60         |
     ...
     | Open_tables              | 1          |
     | Open_files               | 2          |
     | Open_streams             | 0          |
     | Opened_tables            | 44600      |
     | Questions                | 2026873    |
     ...
     | Table_locks_immediate    | 1920382    |
     | Table_locks_waited       | 0          |
     | Threads_cached           | 0          |
     | Threads_created          | 30022      |
     | Threads_connected        | 1          |
     | Threads_running          | 1          |
     | Uptime                   | 80380      |
     +--------------------------+------------+

With a `LIKE' clause, the statement displays only rows for those
variables with names that match the pattern:

     mysql> SHOW STATUS LIKE 'Key%';
     +--------------------+----------+
     | Variable_name      | Value    |
     +--------------------+----------+
     | Key_blocks_used    | 14955    |
     | Key_read_requests  | 96854827 |
     | Key_reads          | 162040   |
     | Key_write_requests | 7589728  |
     | Key_writes         | 3813196  |
     +--------------------+----------+

With the `GLOBAL' modifier, `SHOW STATUS' displays the status values
for all connections to MySQL. With `SESSION', it displays the status
values for the current connection. If no modifier is present, the
default is `SESSION'.  `LOCAL' is a synonym for `SESSION'.

Some status variables have only a global value. For these, you get the
same value for both `GLOBAL' and `SESSION'. The scope for each status
variable is listed at *Note server-status-variables::.

MySQL Enterprise

Status variables provide valuable clues to the state of your servers.
For expert interpretation of the information provided by status
variables, subscribe to the MySQL Enterprise Monitor. For more
information, see `advisors.html'.


File: manual.info,  Node: show-table-status,  Next: show-tables,  Prev: show-status,  Up: show

12.5.5.33 `SHOW TABLE STATUS' Syntax
....................................

     SHOW TABLE STATUS [FROM DB_NAME]
         [LIKE 'PATTERN' | WHERE EXPR]

`SHOW TABLE STATUS' works likes `SHOW TABLES', but provides a lot of
information about each non-`TEMPORARY' table. You can also get this
list using the `mysqlshow --status DB_NAME' command. The `LIKE' clause,
if present, indicates which table names to match. The `WHERE' clause
can be given to select rows using more general conditions, as discussed
in *Note extended-show::.

This statement also displays information about views.

`SHOW TABLE STATUS' returns the following fields:

   * `Name'

     The name of the table.

   * `Engine'

     The storage engine for the table. See *Note storage-engines::.

   * `Version'

     The version number of the table's `.frm' file.

   * `Row_format'

     The row storage format (`Fixed', `Dynamic', `Compressed',
     `Redundant', `Compact').  The format of `InnoDB' tables is reported
     as `Redundant' or `Compact'.

   * `Rows'

     The number of rows. Some storage engines, such as `MyISAM', store
     the exact count. For other storage engines, such as `InnoDB', this
     value is an approximation, and may vary from the actual value by
     as much as 40 to 50%. In such cases, use `SELECT COUNT(*)' to
     obtain an accurate count.

     The `Rows' value is `NULL' for tables in the `INFORMATION_SCHEMA'
     database.

   * `Avg_row_length'

     The average row length.

   * `Data_length'

     The length of the data file.

   * `Max_data_length'

     The maximum length of the data file. This is the total number of
     bytes of data that can be stored in the table, given the data
     pointer size used.

   * `Index_length'

     The length of the index file.

   * `Data_free'

     The number of allocated but unused bytes. Beginning with MySQL
     5.1.24, this information is also shown for `InnoDB' tables.
     (Bug#32440 (http://bugs.mysql.com/32440))

   * `Auto_increment'

     The next `AUTO_INCREMENT' value.

   * `Create_time'

     When the table was created.

   * `Update_time'

     When the data file was last updated. For some storage engines,
     this value is `NULL'. For example, `InnoDB' stores multiple tables
     in its tablespace and the data file timestamp does not apply.

   * `Check_time'

     When the table was last checked. Not all storage engines update
     this time, in which case the value is always `NULL'.

   * `Collation'

     The table's character set and collation.

   * `Checksum'

     The live checksum value (if any).

   * `Create_options'

     Extra options used with `CREATE TABLE'. The original options
     supplied when `CREATE TABLE' is called are retained and the options
     reported here may differ from the active table settings and
     options.

   * `Comment'

     The comment used when creating the table (or information as to why
     MySQL could not access the table information).

In the table comment, `InnoDB' tables report the free space of the
tablespace to which the table belongs. For a table located in the
shared tablespace, this is the free space of the shared tablespace. If
you are using multiple tablespaces and the table has its own
tablespace, the free space is for only that table. Free space means the
number of completely free 1MB extents minus a safety margin. Even if
free space displays as 0, it may be possible to insert rows as long as
new extents need not be allocated.

For `MEMORY' tables, the `Data_length', `Max_data_length', and
`Index_length' values approximate the actual amount of allocated
memory. The allocation algorithm reserves memory in large amounts to
reduce the number of allocation operations.

For `NDBCLUSTER' tables, the output of this statement shows appropriate
values for the `Avg_row_length' and `Data_length' columns, with the
exception that `BLOB' columns are not taken into account. In addition,
the number of replicas is shown in the `Comment' column (as
`number_of_replicas').

For views, all the fields displayed by `SHOW TABLE STATUS' are `NULL'
except that `Name' indicates the view name and `Comment' says `view'.


File: manual.info,  Node: show-tables,  Next: show-triggers,  Prev: show-table-status,  Up: show

12.5.5.34 `SHOW TABLES' Syntax
..............................

     SHOW [FULL] TABLES [FROM DB_NAME]
         [LIKE 'PATTERN' | WHERE EXPR]

`SHOW TABLES' lists the non-`TEMPORARY' tables in a given database. You
can also get this list using the `mysqlshow DB_NAME' command. The
`LIKE' clause, if present, indicates which table names to match. The
`WHERE' clause can be given to select rows using more general
conditions, as discussed in *Note extended-show::.

This statement also lists any views in the database. The `FULL'
modifier is supported such that `SHOW FULL TABLES' displays a second
output column. Values for the second column are `BASE TABLE' for a
table and `VIEW' for a view.

If you have no privileges for a base table or view, it does not show up
in the output from `SHOW TABLES' or `mysqlshow db_name'.


File: manual.info,  Node: show-triggers,  Next: show-variables,  Prev: show-tables,  Up: show

12.5.5.35 `SHOW TRIGGERS' Syntax
................................

     SHOW TRIGGERS [FROM DB_NAME]
         [LIKE 'PATTERN' | WHERE EXPR]

`SHOW TRIGGERS' lists the triggers currently defined for tables in a
database (the default database unless a `FROM' clause is given). This
statement requires the `TRIGGER' privilege (prior to MySQL 5.1.22, it
requires the `SUPER' privilege). The `LIKE' clause, if present,
indicates which table names to match and causes the statement to
display triggers for those tables. The `WHERE' clause can be given to
select rows using more general conditions, as discussed in *Note
extended-show::.

For the trigger `ins_sum' as defined in *Note using-triggers::, the
output of this statement is as shown here:

     mysql> SHOW TRIGGERS LIKE 'acc%'\G
     *************************** 1. row ***************************
                  Trigger: ins_sum
                    Event: INSERT
                    Table: account
                Statement: SET @sum = @sum + NEW.amount
                   Timing: BEFORE
                  Created: NULL
                 sql_mode:
                  Definer: myname@localhost
     character_set_client: latin1
     collation_connection: latin1_swedish_ci
       Database Collation: latin1_swedish_ci

`character_set_client' is the session value of the
`character_set_client' system variable when the trigger was created.
`collation_connection' is the session value of the
`collation_connection' system variable when the trigger was created.
`Database Collation' is the collation of the database with which the
trigger is associated. These columns were added in MySQL 5.1.21.

*Note*:

When using a `LIKE' clause with `SHOW TRIGGERS', the expression to be
matched (EXPR) is compared with the name of the table on which the
trigger is declared, and not with the name of the trigger:

     mysql> SHOW TRIGGERS LIKE 'ins%';
     Empty set (0.01 sec)

A brief explanation of the columns in the output of this statement is
shown here:

   * `Trigger'

     The name of the trigger.

   * `Event'

     The event that causes trigger activation: one of `'INSERT'',
     `'UPDATE'', or `'DELETE''.

   * `Table'

     The table for which the trigger is defined.

   * `Statement'

     The statement to be executed when the trigger is activated.  This
     is the same as the text shown in the `ACTION_STATEMENT' column of
     `INFORMATION_SCHEMA.TRIGGERS'.

   * `Timing'

     One of the two values `'BEFORE'' or `'AFTER''.

   * `Created'

     Currently, the value of this column is always `NULL'.

   * `sql_mode'

     The SQL mode in effect when the trigger executes.

   * `Definer'

     The account that created the trigger.

See also *Note triggers-table::.


File: manual.info,  Node: show-variables,  Next: show-warnings,  Prev: show-triggers,  Up: show

12.5.5.36 `SHOW VARIABLES' Syntax
.................................

     SHOW [GLOBAL | SESSION] VARIABLES
         [LIKE 'PATTERN' | WHERE EXPR]

`SHOW VARIABLES' shows the values of MySQL system variables. This
information also can be obtained using the `mysqladmin variables'
command. The `LIKE' clause, if present, indicates which variable names
to match. The `WHERE' clause can be given to select rows using more
general conditions, as discussed in *Note extended-show::.

With the `GLOBAL' modifier, `SHOW VARIABLES' displays the values that
are used for new connections to MySQL. With `SESSION', it displays the
values that are in effect for the current connection. If no modifier is
present, the default is `SESSION'. `LOCAL' is a synonym for `SESSION'.

If the default system variable values are unsuitable, you can set them
using command options when `mysqld' starts, and most can be changed at
runtime with the `SET' statement. See *Note using-system-variables::,
and *Note set-option::.

Partial output is shown here. The list of names and values may be
different for your server.  *Note server-system-variables::, describes
the meaning of each variable, and *Note server-parameters::, provides
information about tuning them.

     mysql> SHOW VARIABLES;
     +---------------------------------+---------------------------+
     | Variable_name                   | Value                     |
     +---------------------------------+---------------------------+
     | auto_increment_increment        | 1                         |
     | auto_increment_offset           | 1                         |
     | automatic_sp_privileges         | ON                        |
     | back_log                        | 50                        |
     | basedir                         | /home/jon/bin/mysql-5.1/  |
     | binlog_cache_size               | 32768                     |
     | bulk_insert_buffer_size         | 8388608                   |
     | character_set_client            | latin1                    |
     | character_set_connection        | latin1                    |
     ...
     | max_user_connections            | 0                         |
     | max_write_lock_count            | 4294967295                |
     | multi_range_count               | 256                       |
     | myisam_data_pointer_size        | 6                         |
     | myisam_max_sort_file_size       | 2147483647                |
     | myisam_recover_options          | OFF                       |
     | myisam_repair_threads           | 1                         |
     | myisam_sort_buffer_size         | 8388608                   |
     | ndb_autoincrement_prefetch_sz   | 32                        |
     | ndb_cache_check_time            | 0                         |
     | ndb_force_send                  | ON                        |
     ...
     | time_zone                       | SYSTEM                    |
     | timed_mutexes                   | OFF                       |
     | tmp_table_size                  | 33554432                  |
     | tmpdir                          |                           |
     | transaction_alloc_block_size    | 8192                      |
     | transaction_prealloc_size       | 4096                      |
     | tx_isolation                    | REPEATABLE-READ           |
     | updatable_views_with_limit      | YES                       |
     | version                         | 5.1.6-alpha-log           |
     | version_comment                 | Source distribution       |
     | version_compile_machine         | i686                      |
     | version_compile_os              | suse-linux                |
     | wait_timeout                    | 28800                     |
     +---------------------------------+---------------------------+

With a `LIKE' clause, the statement displays only rows for those
variables with names that match the pattern. To obtain the row for a
specific variable, use a `LIKE' clause as shown:

     SHOW VARIABLES LIKE 'max_join_size';
     SHOW SESSION VARIABLES LIKE 'max_join_size';

To get a list of variables whose name match a pattern, use the ``%''
wildcard character in a `LIKE' clause:

     SHOW VARIABLES LIKE '%size%';
     SHOW GLOBAL VARIABLES LIKE '%size%';

Wildcard characters can be used in any position within the pattern to
be matched. Strictly speaking, because ``_'' is a wildcard that matches
any single character, you should escape it as ``\_'' to match it
literally. In practice, this is rarely necessary.


File: manual.info,  Node: show-warnings,  Prev: show-variables,  Up: show

12.5.5.37 `SHOW WARNINGS' Syntax
................................

     SHOW WARNINGS [LIMIT [OFFSET,] ROW_COUNT]
     SHOW COUNT(*) WARNINGS

`SHOW WARNINGS' shows the error, warning, and note messages that
resulted from the last statement that generated messages. It shows
nothing if the last statement used a table and generated no messages.
(That is, a statement that uses a table but generates no messages
clears the message list.)  Statements that do not use tables and do not
generate messages have no effect on the message list.

A related statement, `SHOW ERRORS', shows only the errors. See *Note
show-errors::.

The `SHOW COUNT(*) WARNINGS' statement displays the total number of
errors, warnings, and notes. You can also retrieve this number from the
`warning_count' variable:

     SHOW COUNT(*) WARNINGS;
     SELECT @@warning_count;

The value of `warning_count' might be greater than the number of
messages displayed by `SHOW WARNINGS' if the `max_error_count' system
variable is set so low that not all messages are stored.  An example
shown later in this section demonstrates how this can happen.

The `LIMIT' clause has the same syntax as for the `SELECT' statement.
See *Note select::.

The MySQL server sends back the total number of errors, warnings, and
notes resulting from the last statement. If you are using the C API,
this value can be obtained by calling *Note `mysql_warning_count()':
mysql-warning-count. See *Note mysql-warning-count::.

Warnings are generated for statements such as `LOAD DATA INFILE' and
DML statements such as `INSERT', `UPDATE', `CREATE TABLE', and `ALTER
TABLE'.

The following `DROP TABLE' statement results in a note:

     mysql> DROP TABLE IF EXISTS no_such_table;
     mysql> SHOW WARNINGS;
     +-------+------+-------------------------------+
     | Level | Code | Message                       |
     +-------+------+-------------------------------+
     | Note  | 1051 | Unknown table 'no_such_table' |
     +-------+------+-------------------------------+

Here is a simple example that shows a syntax warning for `CREATE TABLE'
and conversion warnings for `INSERT':

     mysql> CREATE TABLE t1 (a TINYINT NOT NULL, b CHAR(4)) TYPE=MyISAM;
     Query OK, 0 rows affected, 1 warning (0.00 sec)
     mysql> SHOW WARNINGS\G
     *************************** 1. row ***************************
       Level: Warning
        Code: 1287
     Message: 'TYPE=storage_engine' is deprecated, use
              'ENGINE=storage_engine' instead
     1 row in set (0.00 sec)

     mysql> INSERT INTO t1 VALUES(10,'mysql'),(NULL,'test'),
         -> (300,'Open Source');
     Query OK, 3 rows affected, 4 warnings (0.01 sec)
     Records: 3  Duplicates: 0  Warnings: 4

     mysql> SHOW WARNINGS\G
     *************************** 1. row ***************************
       Level: Warning
        Code: 1265
     Message: Data truncated for column 'b' at row 1
     *************************** 2. row ***************************
       Level: Warning
        Code: 1263
     Message: Data truncated, NULL supplied to NOT NULL column 'a' at row 2
     *************************** 3. row ***************************
       Level: Warning
        Code: 1264
     Message: Data truncated, out of range for column 'a' at row 3
     *************************** 4. row ***************************
       Level: Warning
        Code: 1265
     Message: Data truncated for column 'b' at row 3
     4 rows in set (0.00 sec)

The maximum number of error, warning, and note messages to store is
controlled by the `max_error_count' system variable. By default, its
value is 64. To change the number of messages you want stored, change
the value of `max_error_count'. In the following example, the `ALTER
TABLE' statement produces three warning messages, but only one is
stored because `max_error_count' has been set to 1:

     mysql> SHOW VARIABLES LIKE 'max_error_count';
     +-----------------+-------+
     | Variable_name   | Value |
     +-----------------+-------+
     | max_error_count | 64    |
     +-----------------+-------+
     1 row in set (0.00 sec)

     mysql> SET max_error_count=1;
     Query OK, 0 rows affected (0.00 sec)

     mysql> ALTER TABLE t1 MODIFY b CHAR;
     Query OK, 3 rows affected, 3 warnings (0.00 sec)
     Records: 3  Duplicates: 0  Warnings: 3

     mysql> SELECT @@warning_count;
     +-----------------+
     | @@warning_count |
     +-----------------+
     |               3 |
     +-----------------+
     1 row in set (0.01 sec)

     mysql> SHOW WARNINGS;
     +---------+------+----------------------------------------+
     | Level   | Code | Message                                |
     +---------+------+----------------------------------------+
     | Warning | 1263 | Data truncated for column 'b' at row 1 |
     +---------+------+----------------------------------------+
     1 row in set (0.00 sec)

To disable warnings, set `max_error_count' to 0. In this case,
`warning_count' still indicates how many warnings have occurred, but
none of the messages are stored.

You can set the `SQL_NOTES' session variable to 0 to cause `Note'-level
warnings not to be recorded.


File: manual.info,  Node: other-administrative-sql,  Prev: show,  Up: sql-syntax-server-administration

12.5.6 Other Administrative Statements
--------------------------------------

* Menu:

* cache-index::                  `CACHE INDEX' Syntax
* flush::                        `FLUSH' Syntax
* kill::                         `KILL' Syntax
* load-index::                   `LOAD INDEX INTO CACHE' Syntax
* reset::                        `RESET' Syntax


File: manual.info,  Node: cache-index,  Next: flush,  Prev: other-administrative-sql,  Up: other-administrative-sql

12.5.6.1 `CACHE INDEX' Syntax
.............................

     CACHE INDEX
       TBL_INDEX_LIST [, TBL_INDEX_LIST] ...
       IN KEY_CACHE_NAME

     TBL_INDEX_LIST:
       TBL_NAME [[INDEX|KEY] (INDEX_NAME[, INDEX_NAME] ...)]

The `CACHE INDEX' statement assigns table indexes to a specific key
cache. It is used only for `MyISAM' tables.

The following statement assigns indexes from the tables `t1', `t2', and
`t3' to the key cache named `hot_cache':

     mysql> CACHE INDEX t1, t2, t3 IN hot_cache;
     +---------+--------------------+----------+----------+
     | Table   | Op                 | Msg_type | Msg_text |
     +---------+--------------------+----------+----------+
     | test.t1 | assign_to_keycache | status   | OK       |
     | test.t2 | assign_to_keycache | status   | OK       |
     | test.t3 | assign_to_keycache | status   | OK       |
     +---------+--------------------+----------+----------+

The syntax of `CACHE INDEX' enables you to specify that only particular
indexes from a table should be assigned to the cache. The current
implementation assigns all the table's indexes to the cache, so there
is no reason to specify anything other than the table name.

The key cache referred to in a `CACHE INDEX' statement can be created
by setting its size with a parameter setting statement or in the server
parameter settings. For example:

     mysql> SET GLOBAL keycache1.key_buffer_size=128*1024;

Key cache parameters can be accessed as members of a structured system
variable. See *Note structured-system-variables::.

A key cache must exist before you can assign indexes to it:

     mysql> CACHE INDEX t1 IN non_existent_cache;
     ERROR 1284 (HY000): Unknown key cache 'non_existent_cache'

By default, table indexes are assigned to the main (default) key cache
created at the server startup. When a key cache is destroyed, all
indexes assigned to it become assigned to the default key cache again.

Index assignment affects the server globally: If one client assigns an
index to a given cache, this cache is used for all queries involving
the index, no matter which client issues the queries.


File: manual.info,  Node: flush,  Next: kill,  Prev: cache-index,  Up: other-administrative-sql

12.5.6.2 `FLUSH' Syntax
.......................

     FLUSH [LOCAL | NO_WRITE_TO_BINLOG]
         FLUSH_OPTION [, FLUSH_OPTION] ...

The `FLUSH' statement clears or reloads various internal caches used by
MySQL. To execute `FLUSH', you must have the `RELOAD' privilege.

The `RESET' statement is similar to `FLUSH'. See *Note reset::.

FLUSH_OPTION can be any of the following:

   * `DES_KEY_FILE'

     Reloads the DES keys from the file that was specified with the
     `--des-key-file' option at server startup time.

   * `HOSTS'

     Empties the host cache tables. You should flush the host tables if
     some of your hosts change IP number or if you get the error
     message `Host 'HOST_NAME' is blocked'.  When more than
     `max_connect_errors' errors occur successively for a given host
     while connecting to the MySQL server, MySQL assumes that something
     is wrong and blocks the host from further connection requests.
     Flushing the host tables enables further connection attempts from
     the host. See *Note blocked-host::. You can start `mysqld' with
     `--max_connect_errors=999999999' to avoid this error message.

   * `LOGS'

     Closes and reopens all log files. If binary logging is enabled,
     the sequence number of the binary log file is incremented by one
     relative to the previous file. On Unix, this is the same thing as
     sending a `SIGHUP' signal to the `mysqld' server (except on some
     Mac OS X 10.3 versions where `mysqld' ignores `SIGHUP' and
     `SIGQUIT').

     If the server is writing error output to a named file (for
     example, if it was started with the `--log-error' option), `FLUSH
     LOGS' causes it to rename the current error log file with a suffix
     of `-old' and create a new empty log file. No renaming occurs if
     the server is not writing to a named file (for example, if it is
     writing errors to the console).

   * `MASTER' (_DEPRECATED_).  Deletes all binary logs, resets the
     binary log index file and creates a new binary log. `FLUSH MASTER'
     is deprecated in favor of `RESET MASTER', and is supported for
     backward compatibility only. See *Note reset-master::.

   * `PRIVILEGES'

     Reloads the privileges from the grant tables in the `mysql'
     database. On Unix, this also occurs if the server receives a
     `SIGHUP' signal.

     The server caches information in memory as a result of `GRANT',
     `CREATE USER', `CREATE SERVER', and `INSTALL PLUGIN' statements.
     This memory is not released by the corresponding `REVOKE', `DROP
     USER', `DROP SERVER', and `UNINSTALL PLUGIN' statements, so for a
     server that executes many instances of the statements that cause
     caching, there will be an increase in memory use. This cached
     memory can be freed with `FLUSH PRIVILEGES'.

   * `QUERY CACHE'

     Defragment the query cache to better utilize its memory.  `FLUSH
     QUERY CACHE' does not remove any queries from the cache, unlike
     `FLUSH TABLES' or `RESET QUERY CACHE'.

   * `SLAVE' (_DEPRECATED_).  Resets all replication slave parameters,
     including relay log files and replication position in the master's
     binary logs.  `FLUSH SLAVE' is deprecated in favor of `RESET
     SLAVE', and is supported for backward compatibility only. See
     *Note reset-slave::.

   * `STATUS'

     This option adds the current thread's session status variable
     values to the global values and resets the session values to zero.
     It also resets the counters for key caches (default and named) to
     zero and sets `Max_used_conections' to the current number of open
     connections. This is something you should use only when debugging
     a query. See *Note bug-reports::.

   * `{TABLE | TABLES} [TBL_NAME [, TBL_NAME] ...]'

     When no tables are named, closes all open tables, forces all
     tables in use to be closed, and flushes the query cache.  With one
     or more table names, flushes only the given tables.  `FLUSH
     TABLES' also removes all query results from the query cache, like
     the `RESET QUERY CACHE' statement.

   * `TABLES WITH READ LOCK'

     Closes all open tables and locks all tables for all databases with
     a read lock until you explicitly release the lock by executing
     `UNLOCK TABLES'. This is very convenient way to get backups if you
     have a filesystem such as Veritas that can take snapshots in time.

     `FLUSH TABLES WITH READ LOCK' acquires a global read lock and not
     table locks, so it is not subject to the same behavior as `LOCK
     TABLES' and `UNLOCK TABLES' with respect to table locking and
     implicit commits:

        * `UNLOCK TABLES' implicitly commits any active transaction
          only if any tables currently have been locked with `LOCK
          TABLES'. The commit does not occur for `UNLOCK TABLES'
          following `FLUSH TABLES WITH READ LOCK' because the latter
          statement does not acquire table locks.

        * Beginning a transaction causes table locks acquired with
          `LOCK TABLES' to be released, as though you had executed
          `UNLOCK TABLES'.  Beginning a transaction does not release a
          global read lock acquired with `FLUSH TABLES WITH READ LOCK'.

   * `USER_RESOURCES'

     Resets all per-hour user resources to zero. This enables clients
     that have reached their hourly connection, query, or update limits
     to resume activity immediately. `FLUSH USER_RESOURCES' does not
     apply to the limit on maximum simultaneous connections. See *Note
     grant::.

By default, `FLUSH' statements are written to the binary log. Such
statements used on a MySQL server acting as a replication master will
be replicated to replication slaves.  Logging can be suppressed with
the optional `NO_WRITE_TO_BINLOG' keyword or its alias `LOCAL'.

See also *Note reset::, for information about how the `RESET' statement
is used with replication.

*Note*:

`FLUSH LOGS', `FLUSH MASTER', `FLUSH SLAVE', and `FLUSH TABLES WITH
READ LOCK' are not written to the binary log in any case because they
would cause problems if replicated to a slave.

The `mysqladmin' utility provides a command-line interface to some
flush operations, via the `flush-hosts', `flush-logs',
`flush-privileges', `flush-status', and `flush-tables' commands.

*Note*:

It is not possible in MySQL 5.1 to issue `FLUSH' statements within
stored functions or triggers. However, you may use `FLUSH' in stored
procedures, so long as these are not called from stored functions or
triggers. See *Note routine-restrictions::.


File: manual.info,  Node: kill,  Next: load-index,  Prev: flush,  Up: other-administrative-sql

12.5.6.3 `KILL' Syntax
......................

     KILL [CONNECTION | QUERY] THREAD_ID

Each connection to `mysqld' runs in a separate thread. You can see
which threads are running with the `SHOW PROCESSLIST' statement and
kill a thread with the `KILL THREAD_ID' statement.

`KILL' allows the optional `CONNECTION' or `QUERY' modifier:

   * `KILL CONNECTION' is the same as `KILL' with no modifier: It
     terminates the connection associated with the given THREAD_ID.

   * `KILL QUERY' terminates the statement that the connection is
     currently executing, but leaves the connection itself intact.

If you have the `PROCESS' privilege, you can see all threads. If you
have the `SUPER' privilege, you can kill all threads and statements.
Otherwise, you can see and kill only your own threads and statements.

You can also use the `mysqladmin processlist' and `mysqladmin kill'
commands to examine and kill threads.

*Note*:

You cannot use `KILL' with the Embedded MySQL Server library, because
the embedded server merely runs inside the threads of the host
application. It does not create any connection threads of its own.

When you use `KILL', a thread-specific kill flag is set for the thread.
In most cases, it might take some time for the thread to die, because
the kill flag is checked only at specific intervals:

   * In `SELECT', `ORDER BY' and `GROUP BY' loops, the flag is checked
     after reading a block of rows. If the kill flag is set, the
     statement is aborted.

   * During `ALTER TABLE', the kill flag is checked before each block
     of rows are read from the original table. If the kill flag was
     set, the statement is aborted and the temporary table is deleted.

   * During `UPDATE' or `DELETE' operations, the kill flag is checked
     after each block read and after each updated or deleted row. If
     the kill flag is set, the statement is aborted. Note that if you
     are not using transactions, the changes are not rolled back.

   * `GET_LOCK()' aborts and returns `NULL'.

   * An `INSERT DELAYED' thread quickly flushes (inserts) all rows it
     has in memory and then terminates.

   * If the thread is in the table lock handler (state: `Locked'), the
     table lock is quickly aborted.

   * If the thread is waiting for free disk space in a write call, the
     write is aborted with a `disk full' error message.

   * *Warning*:

     Killing a `REPAIR TABLE' or `OPTIMIZE TABLE' operation on a
     `MyISAM' table results in a table that is corrupted and unusable.
     Any reads or writes to such a table fail until you optimize or
     repair it again (without interruption).


File: manual.info,  Node: load-index,  Next: reset,  Prev: kill,  Up: other-administrative-sql

12.5.6.4 `LOAD INDEX INTO CACHE' Syntax
.......................................

     LOAD INDEX INTO CACHE
       TBL_INDEX_LIST [, TBL_INDEX_LIST] ...

     TBL_INDEX_LIST:
       TBL_NAME
         [[INDEX|KEY] (INDEX_NAME[, INDEX_NAME] ...)]
         [IGNORE LEAVES]

The `LOAD INDEX INTO CACHE' statement preloads a table index into the
key cache to which it has been assigned by an explicit `CACHE INDEX'
statement, or into the default key cache otherwise. `LOAD INDEX INTO
CACHE' is used only for `MyISAM' tables. It is not supported for tables
having user-defined partitioning (see *Note partitioning-limitations::.)

The `IGNORE LEAVES' modifier causes only blocks for the non-leaf nodes
of the index to be preloaded.

The following statement preloads nodes (index blocks) of indexes for
the tables `t1' and `t2':

     mysql> LOAD INDEX INTO CACHE t1, t2 IGNORE LEAVES;
     +---------+--------------+----------+----------+
     | Table   | Op           | Msg_type | Msg_text |
     +---------+--------------+----------+----------+
     | test.t1 | preload_keys | status   | OK       |
     | test.t2 | preload_keys | status   | OK       |
     +---------+--------------+----------+----------+

This statement preloads all index blocks from `t1'. It preloads only
blocks for the non-leaf nodes from `t2'.

The syntax of `LOAD INDEX INTO CACHE' enables you to specify that only
particular indexes from a table should be preloaded. The current
implementation preloads all the table's indexes into the cache, so
there is no reason to specify anything other than the table name.

`LOAD INDEX INTO CACHE ... IGNORE LEAVES' fails unless all indexes in a
table have the same block size. (Prior to MySQL 5.1.19, it fails even
without `IGNORE LEAVES'.) You can determine index block sizes for a
table by using `myisamchk -dv' and checking the `Blocksize' column.


File: manual.info,  Node: reset,  Prev: load-index,  Up: other-administrative-sql

12.5.6.5 `RESET' Syntax
.......................

     RESET RESET_OPTION [, RESET_OPTION] ...

The `RESET' statement is used to clear the state of various server
operations. You must have the `RELOAD' privilege to execute `RESET'.

`RESET' acts as a stronger version of the `FLUSH' statement. See *Note
flush::.

RESET_OPTION can be any of the following:

   * `MASTER'

     Deletes all binary logs listed in the index file, resets the
     binary log index file to be empty, and creates a new binary log
     file.

   * `QUERY CACHE'

     Removes all query results from the query cache.

   * `SLAVE'

     Makes the slave forget its replication position in the master
     binary logs. Also resets the relay log by deleting any existing
     relay log files and beginning a new one.


File: manual.info,  Node: sql-syntax-replication,  Next: sql-syntax-prepared-statements,  Prev: sql-syntax-server-administration,  Up: sql-syntax

12.6 Replication Statements
===========================

* Menu:

* replication-master-sql::       SQL Statements for Controlling Master Servers
* replication-slave-sql::        SQL Statements for Controlling Slave Servers

This section describes SQL statements related to replication. One group
of statements is used for controlling master servers. The other is used
for controlling slave servers.


File: manual.info,  Node: replication-master-sql,  Next: replication-slave-sql,  Prev: sql-syntax-replication,  Up: sql-syntax-replication

12.6.1 SQL Statements for Controlling Master Servers
----------------------------------------------------

* Menu:

* purge-master-logs::            `PURGE MASTER LOGS' Syntax
* reset-master::                 `RESET MASTER' Syntax
* set-sql-log-bin::              `SET SQL_LOG_BIN' Syntax

Replication can be controlled through the SQL interface. This section
discusses statements for managing master replication servers. *Note
replication-slave-sql::, discusses statements for managing slave
servers.

The following `SHOW' statements are used with master servers in
replication:

   * `SHOW BINARY LOGS'

   * `SHOW BINLOG EVENTS'

   * `SHOW MASTER STATUS'

   * `SHOW SLAVE HOSTS'

For information about these statements, see *Note show::.


File: manual.info,  Node: purge-master-logs,  Next: reset-master,  Prev: replication-master-sql,  Up: replication-master-sql

12.6.1.1 `PURGE MASTER LOGS' Syntax
...................................

     PURGE {MASTER | BINARY} LOGS TO 'LOG_NAME'
     PURGE {MASTER | BINARY} LOGS BEFORE 'DATE'

Deletes all the binary logs listed in the log index prior to the
specified log or date. The logs also are removed from the list recorded
in the log index file, so that the given log becomes the first.

This statement has no effect if the `--log-bin' option has not been
enabled.

Example:

     PURGE MASTER LOGS TO 'mysql-bin.010';
     PURGE MASTER LOGS BEFORE '2003-04-02 22:46:26';

The `BEFORE' variant's DATE argument can be in `'YYYY-MM-DD hh:mm:ss''
format.  `MASTER' and `BINARY' are synonyms.

This statement is safe to run while slaves are replicating. You do not
need to stop them. If you have an active slave that currently is
reading one of the logs you are trying to delete, this statement does
nothing and fails with an error. However, if a slave is dormant and you
happen to purge one of the logs it has yet to read, the slave will be
unable to replicate after it comes up.

To safely purge logs, follow this procedure:

  1. On each slave server, use `SHOW SLAVE STATUS' to check which log
     it is reading.

  2. Obtain a listing of the binary logs on the master server with
     `SHOW BINARY LOGS'.

  3. Determine the earliest log among all the slaves. This is the
     target log. If all the slaves are up to date, this is the last log
     on the list.

  4. Make a backup of all the logs you are about to delete. (This step
     is optional, but always advisable.)

  5. Purge all logs up to but not including the target log.

You can also set the `expire_logs_days' system variable to expire
binary log files automatically after a given number of days (see *Note
server-system-variables::).  If you are using replication, you should
set the variable no lower than the maximum number of days your slaves
might lag behind the master.

Prior to MySQL 5.1.24, `PURGE BINARY LOGS TO' and `PURGE BINARY LOGS
BEFORE' did not behave in the same way (and neither one behaved
correctly) when binary log files listed in the `.index' file had been
removed from the system by some other means (such as using rm on
Linux). Beginning with MySQL 5.1.24, both variants of the statement
fail with an error in such cases. (Bug#18199
(http://bugs.mysql.com/18199), Bug#18453 (http://bugs.mysql.com/18453))
You can handle such errors by editing the `.index' file (which is a
simple text file) manually and insuring that it lists only the binlog
files that are actually present, then running again the `PURGE BINARY
LOGS' statement that failed.


File: manual.info,  Node: reset-master,  Next: set-sql-log-bin,  Prev: purge-master-logs,  Up: replication-master-sql

12.6.1.2 `RESET MASTER' Syntax
..............................

     RESET MASTER

Deletes all binary logs listed in the index file, resets the binary log
index file to be empty, and creates a new binary log file.


File: manual.info,  Node: set-sql-log-bin,  Prev: reset-master,  Up: replication-master-sql

12.6.1.3 `SET SQL_LOG_BIN' Syntax
.................................

     SET SQL_LOG_BIN = {0|1}

Disables or enables binary logging for the current connection
(`SQL_LOG_BIN' is a session variable) if the client has the `SUPER'
privilege. The statement is refused with an error if the client does
not have that privilege.


File: manual.info,  Node: replication-slave-sql,  Prev: replication-master-sql,  Up: sql-syntax-replication

12.6.2 SQL Statements for Controlling Slave Servers
---------------------------------------------------

* Menu:

* change-master-to::             `CHANGE MASTER TO' Syntax
* load-data-from-master::        `LOAD DATA FROM MASTER' Syntax
* load-table-from-master::       `LOAD TABLE TBL_NAME FROM MASTER' Syntax
* master-pos-wait::              `MASTER_POS_WAIT()' Syntax
* reset-slave::                  `RESET SLAVE' Syntax
* set-global-sql-slave-skip-counter::  `SET GLOBAL SQL_SLAVE_SKIP_COUNTER' Syntax
* start-slave::                  `START SLAVE' Syntax
* stop-slave::                   `STOP SLAVE' Syntax

Replication can be controlled through the SQL interface. This section
discusses statements for managing slave replication servers. *Note
replication-master-sql::, discusses statements for managing master
servers.

`SHOW SLAVE STATUS' is also used with replication slaves. For
information about this statement, see *Note show-slave-status::.


File: manual.info,  Node: change-master-to,  Next: load-data-from-master,  Prev: replication-slave-sql,  Up: replication-slave-sql

12.6.2.1 `CHANGE MASTER TO' Syntax
..................................

     CHANGE MASTER TO MASTER_DEF [, MASTER_DEF] ...

     MASTER_DEF:
         MASTER_BIND = 'INTERFACE_NAME'
       | MASTER_HOST = 'HOST_NAME'
       | MASTER_USER = 'USER_NAME'
       | MASTER_PASSWORD = 'PASSWORD'
       | MASTER_PORT = PORT_NUM
       | MASTER_CONNECT_RETRY = INTERVAL
       | MASTER_HEARTBEAT_PERIOD = INTERVAL
       | MASTER_LOG_FILE = 'MASTER_LOG_NAME'
       | MASTER_LOG_POS = MASTER_LOG_POS
       | RELAY_LOG_FILE = 'RELAY_LOG_NAME'
       | RELAY_LOG_POS = RELAY_LOG_POS
       | MASTER_SSL = {0|1}
       | MASTER_SSL_CA = 'CA_FILE_NAME'
       | MASTER_SSL_CAPATH = 'CA_DIRECTORY_NAME'
       | MASTER_SSL_CERT = 'CERT_FILE_NAME'
       | MASTER_SSL_KEY = 'KEY_FILE_NAME'
       | MASTER_SSL_CIPHER = 'CIPHER_LIST'
       | MASTER_SSL_VERIFY_SERVER_CERT = {0|1}

`CHANGE MASTER TO' changes the parameters that the slave server uses
for connecting to and communicating with the master server. It also
updates the contents of the `master.info' and `relay-log.info' files.

`MASTER_USER', `MASTER_PASSWORD', `MASTER_SSL', `MASTER_SSL_CA',
`MASTER_SSL_CAPATH', `MASTER_SSL_CERT', `MASTER_SSL_KEY',
`MASTER_SSL_CIPHER', and `MASTER_SSL_VERIFY_SERVER_CERT' provide
information to the slave about how to connect to its master.
`MASTER_SSL_VERIFY_SERVER_CERT' was added in MySQL 5.1.18. It is used
as described for the `--ssl-verify-server-cert' option in *Note
ssl-options::.

`MASTER_CONNECT_RETRY' specifies how many seconds to wait between
connect retries. The default is 60. The _number_ of reconnection
attempts is limited by the `--master-retry-count' server option; for
more information, see *Note replication-options::.

The SSL options (`MASTER_SSL', `MASTER_SSL_CA', `MASTER_SSL_CAPATH',
`MASTER_SSL_CERT', `MASTER_SSL_KEY', `MASTER_SSL_CIPHER'), and
`MASTER_SSL_VERIFY_SERVER_CERT' can be changed even on slaves that are
compiled without SSL support. They are saved to the `master.info' file,
but are ignored unless you use a server that has SSL support enabled.

If you don't specify a given parameter, it keeps its old value, except
as indicated in the following discussion. For example, if the password
to connect to your MySQL master has changed, you just need to issue
these statements to tell the slave about the new password:

     STOP SLAVE; -- if replication was running
     CHANGE MASTER TO MASTER_PASSWORD='new3cret';
     START SLAVE; -- if you want to restart replication

There is no need to specify the parameters that do not change (host,
port, user, and so forth).

`MASTER_HOST' and `MASTER_PORT' are the hostname (or IP address) of the
master host and its TCP/IP port. Note that if `MASTER_HOST' is equal to
`localhost', then, like in other parts of MySQL, the port number might
be ignored.

`MASTER_BIND' is for use on replication slaves having multiple network
interfaces, and determines which of the slave's network interfaces is
chosen for connecting to the master. It is also possible to determine
which network interface is to be used in such cases by starting the
slave mysqld process with the `--master-bind' option.

The ability to bind a replication slave to specific network interface
was added in MySQL Cluster NDB 6.3.4.

`MASTER_HEARTBEAT_PERIOD' is used to set the interval in seconds
between replication heartbeats. Whenever the master's binlog is updated
with an event, the waiting period for the next heartbeat is reset.
INTERVAL is a decimal value having the range 0 to 4294967 seconds and a
resolution to hundredths of a second; the smallest nonzero value is
0.001. Heartbeats are sent by the master only if there are no unsent
events in the binlog file for a period longer than INTERVAL.

Setting INTERVAL to 0 disables heartbeats altogether. The default value
for INTERVAL is equal to the value of `slave_net_timeout' divided by 2.

*Note*:

Setting `@@global.slave_net_timeout' to a value less than that of the
current heartbeat interval results in a warning being issued.

Issuing `RESET SLAVE' resets the hearbeat interval to the default.

`MASTER_HEARTBEAT_PERIOD' was added in MySQL Cluster NDB 6.3.4.

*Note*:

Replication cannot use Unix socket files. You must be able to connect
to the master MySQL server using TCP/IP.

If you specify `MASTER_HOST' or `MASTER_PORT', the slave assumes that
the master server is different from before (even if you specify a host
or port value that is the same as the current value.) In this case, the
old values for the master binary log name and position are considered
no longer applicable, so if you do not specify `MASTER_LOG_FILE' and
`MASTER_LOG_POS' in the statement, `MASTER_LOG_FILE=''' and
`MASTER_LOG_POS=4' are silently appended to it.

`MASTER_LOG_FILE' and `MASTER_LOG_POS' are the coordinates at which the
slave I/O thread should begin reading from the master the next time the
thread starts. If you specify either of them, you cannot specify
`RELAY_LOG_FILE' or `RELAY_LOG_POS'. If neither of `MASTER_LOG_FILE' or
`MASTER_LOG_POS' are specified, the slave uses the last coordinates of
the _slave SQL thread_ before `CHANGE MASTER' was issued. This ensures
that there is no discontinuity in replication, even if the slave SQL
thread was late compared to the slave I/O thread, when you merely want
to change, say, the password to use.

`CHANGE MASTER' _deletes all relay log files_ and starts a new one,
unless you specify `RELAY_LOG_FILE' or `RELAY_LOG_POS'. In that case,
relay logs are kept; the `relay_log_purge' global variable is set
silently to 0.

`CHANGE MASTER' is useful for setting up a slave when you have the
snapshot of the master and have recorded the log and the offset
corresponding to it. After loading the snapshot into the slave, you can
run `CHANGE MASTER TO MASTER_LOG_FILE='LOG_NAME_ON_MASTER',
MASTER_LOG_POS=LOG_OFFSET_ON_MASTER' on the slave.

The following example changes the master and master's binary log
coordinates. This is used when you want to set up the slave to
replicate the master:

     CHANGE MASTER TO
       MASTER_HOST='master2.mycompany.com',
       MASTER_USER='replication',
       MASTER_PASSWORD='bigs3cret',
       MASTER_PORT=3306,
       MASTER_LOG_FILE='master2-bin.001',
       MASTER_LOG_POS=4,
       MASTER_CONNECT_RETRY=10;

The next example shows an operation that is less frequently employed.
It is used when the slave has relay logs that you want it to execute
again for some reason. To do this, the master need not be reachable.
You need only use `CHANGE MASTER TO' and start the SQL thread (`START
SLAVE SQL_THREAD'):

     CHANGE MASTER TO
       RELAY_LOG_FILE='slave-relay-bin.006',
       RELAY_LOG_POS=4025;

You can even use the second operation in a non-replication setup with a
standalone, non-slave server for recovery following a crash. Suppose
that your server has crashed and you have restored a backup. You want
to replay the server's own binary logs (not relay logs, but regular
binary logs), named (for example) `myhost-bin.*'. First, make a backup
copy of these binary logs in some safe place, in case you don't exactly
follow the procedure below and accidentally have the server purge the
binary logs. Use `SET GLOBAL relay_log_purge=0' for additional safety.
Then start the server without the `--log-bin' option, Instead, use the
`--replicate-same-server-id', `--relay-log=myhost-bin' (to make the
server believe that these regular binary logs are relay logs) and
`--skip-slave-start' options. After the server starts, issue these
statements:

     CHANGE MASTER TO
       RELAY_LOG_FILE='myhost-bin.153',
       RELAY_LOG_POS=410,
       MASTER_HOST='some_dummy_string';
     START SLAVE SQL_THREAD;

The server reads and executes its own binary logs, thus achieving crash
recovery. Once the recovery is finished, run `STOP SLAVE', shut down
the server, delete the `master.info' and `relay-log.info' files, and
restart the server with its original options.

Specifying the `MASTER_HOST' option (even with a dummy value) is
required to make the server think it is a slave.


File: manual.info,  Node: load-data-from-master,  Next: load-table-from-master,  Prev: change-master-to,  Up: replication-slave-sql

12.6.2.2 `LOAD DATA FROM MASTER' Syntax
.......................................

     LOAD DATA FROM MASTER

*This feature is deprecated. We recommend not using it anymore. It is
subject to removal in a future version of MySQL.*

Since the current implementation of `LOAD DATA FROM MASTER' and `LOAD
TABLE FROM MASTER' is very limited, these statements are deprecated in
versions 4.1 of MySQL and above. We will introduce a more advanced
technique (called `online backup') in a future version. That technique
will have the additional advantage of working with more storage engines.

For MySQL 5.1 and earlier, the recommended alternative solution to
using `LOAD DATA FROM MASTER' or `LOAD TABLE FROM MASTER' is using
`mysqldump' or `mysqlhotcopy'.  The latter requires Perl and two Perl
modules (`DBI' and `DBD:mysql') and works for `MyISAM' and `ARCHIVE'
tables only. With `mysqldump', you can create SQL dumps on the master
and pipe (or copy) these to a `mysql' client on the slave. This has the
advantage of working for all storage engines, but can be quite slow,
since it works using `SELECT'.

This statement takes a snapshot of the master and copies it to the
slave. It updates the values of `MASTER_LOG_FILE' and `MASTER_LOG_POS'
so that the slave starts replicating from the correct position. Any
table and database exclusion rules specified with the
`--replicate-*-do-*' and `--replicate-*-ignore-*' options are honored.
`--replicate-rewrite-db' is _not_ taken into account because a user
could use this option to set up a non-unique mapping such as
`--replicate-rewrite-db="db1->db3"' and
`--replicate-rewrite-db="db2->db3"', which would confuse the slave when
loading tables from the master.

Use of this statement is subject to the following conditions:

   * It works only for `MyISAM' tables.  Attempting to load a
     non-`MyISAM' table results in the following error:

          ERROR 1189 (08S01): Net error reading from master

   * It acquires a global read lock on the master while taking the
     snapshot, which prevents updates on the master during the load
     operation.

If you are loading large tables, you might have to increase the values
of `net_read_timeout' and `net_write_timeout' on both the master and
slave servers. See *Note server-system-variables::.

Note that `LOAD DATA FROM MASTER' does _not_ copy any tables from the
`mysql' database. This makes it easy to have different users and
privileges on the master and the slave.

To use `LOAD DATA FROM MASTER', the replication account that is used to
connect to the master must have the `RELOAD' and `SUPER' privileges on
the master and the `SELECT' privilege for all master tables you want to
load. All master tables for which the user does not have the `SELECT'
privilege are ignored by `LOAD DATA FROM MASTER'. This is because the
master hides them from the user: `LOAD DATA FROM MASTER' calls `SHOW
DATABASES' to know the master databases to load, but `SHOW DATABASES'
returns only databases for which the user has some privilege. See *Note
show-databases::. On the slave side, the user that issues `LOAD DATA
FROM MASTER' must have privileges for dropping and creating the
databases and tables that are copied.


File: manual.info,  Node: load-table-from-master,  Next: master-pos-wait,  Prev: load-data-from-master,  Up: replication-slave-sql

12.6.2.3 `LOAD TABLE TBL_NAME FROM MASTER' Syntax
.................................................

     LOAD TABLE TBL_NAME FROM MASTER

*This feature is deprecated. We recommend not using it anymore. It is
subject to removal in a future version of MySQL.*

Since the current implementation of `LOAD DATA FROM MASTER' and `LOAD
TABLE FROM MASTER' is very limited, these statements are deprecated in
versions 4.1 of MySQL and above. We will introduce a more advanced
technique (called `online backup') in a future version. That technique
will have the additional advantage of working with more storage engines.

For MySQL 5.1 and earlier, the recommended alternative solution to
using `LOAD DATA FROM MASTER' or `LOAD TABLE FROM MASTER' is using
`mysqldump' or `mysqlhotcopy'.  The latter requires Perl and two Perl
modules (`DBI' and `DBD:mysql') and works for `MyISAM' and `ARCHIVE'
tables only. With `mysqldump', you can create SQL dumps on the master
and pipe (or copy) these to a `mysql' client on the slave. This has the
advantage of working for all storage engines, but can be quite slow,
since it works using `SELECT'.

Transfers a copy of the table from the master to the slave. This
statement is implemented mainly debugging `LOAD DATA FROM MASTER'
operations. To use `LOAD TABLE', the account used for connecting to the
master server must have the `RELOAD' and `SUPER' privileges on the
master and the `SELECT' privilege for the master table to load. On the
slave side, the user that issues `LOAD TABLE FROM MASTER' must have
privileges for dropping and creating the table.

The conditions for `LOAD DATA FROM MASTER' apply here as well. For
example, `LOAD TABLE FROM MASTER' works only for `MyISAM' tables. The
timeout notes for `LOAD DATA FROM MASTER' apply as well.


File: manual.info,  Node: master-pos-wait,  Next: reset-slave,  Prev: load-table-from-master,  Up: replication-slave-sql

12.6.2.4 `MASTER_POS_WAIT()' Syntax
...................................

     SELECT MASTER_POS_WAIT('MASTER_LOG_FILE', MASTER_LOG_POS [, TIMEOUT])

This is actually a function, not a statement. It is used to ensure that
the slave has read and executed events up to a given position in the
master's binary log. See *Note miscellaneous-functions::, for a full
description.


File: manual.info,  Node: reset-slave,  Next: set-global-sql-slave-skip-counter,  Prev: master-pos-wait,  Up: replication-slave-sql

12.6.2.5 `RESET SLAVE' Syntax
.............................

     RESET SLAVE

`RESET SLAVE' makes the slave forget its replication position in the
master's binary logs. This statement is meant to be used for a clean
start: It deletes the `master.info' and `relay-log.info' files, all the
relay logs, and starts a new relay log.

*Note*:

All relay logs are deleted, even if they have not been completely
executed by the slave SQL thread. (This is a condition likely to exist
on a replication slave if you have issued a `STOP SLAVE' statement or
if the slave is highly loaded.)

Connection information stored in the `master.info' file is immediately
reset using any values specified in the corresponding startup options.
This information includes values such as master host, master port,
master user, and master password. If the slave SQL thread was in the
middle of replicating temporary tables when it was stopped, and `RESET
SLAVE' is issued, these replicated temporary tables are deleted on the
slave.


File: manual.info,  Node: set-global-sql-slave-skip-counter,  Next: start-slave,  Prev: reset-slave,  Up: replication-slave-sql

12.6.2.6 `SET GLOBAL SQL_SLAVE_SKIP_COUNTER' Syntax
...................................................

     SET GLOBAL SQL_SLAVE_SKIP_COUNTER = N

This statement skips the next N events from the master. This is useful
for recovering from replication stops caused by a statement.

This statement is valid only when the slave thread is not running.
Otherwise, it produces an error.


File: manual.info,  Node: start-slave,  Next: stop-slave,  Prev: set-global-sql-slave-skip-counter,  Up: replication-slave-sql

12.6.2.7 `START SLAVE' Syntax
.............................

     START SLAVE [THREAD_TYPE [, THREAD_TYPE] ... ]
     START SLAVE [SQL_THREAD] UNTIL
         MASTER_LOG_FILE = 'LOG_NAME', MASTER_LOG_POS = LOG_POS
     START SLAVE [SQL_THREAD] UNTIL
         RELAY_LOG_FILE = 'LOG_NAME', RELAY_LOG_POS = LOG_POS

     THREAD_TYPE: IO_THREAD | SQL_THREAD

`START SLAVE' with no THREAD_TYPE options starts both of the slave
threads. The I/O thread reads queries from the master server and stores
them in the relay log. The SQL thread reads the relay log and executes
the queries. `START SLAVE' requires the `SUPER' privilege.

If `START SLAVE' succeeds in starting the slave threads, it returns
without any error. However, even in that case, it might be that the
slave threads start and then later stop (for example, because they do
not manage to connect to the master or read its binary logs, or some
other problem).  `START SLAVE' does not warn you about this. You must
check the slave's error log for error messages generated by the slave
threads, or check that they are running satisfactorily with `SHOW SLAVE
STATUS'.

`START SLAVE' sends an acknowledgement to the user after both the IO
thread and the SQL thread have started.  However, the IO thread may not
yet have connected. For this reason, a successful `START SLAVE' causes
`SHOW SLAVE STATUS' to show `Slave_SQL_Running=Yes', but this does not
guarantee that `Slave_IO_Running=Yes' (because `Slave_IO_Running=Yes'
only if the IO thread is running _and connected_). For more
information, see *Note show-slave-status::, and *Note
replication-administration-status::.

You can add `IO_THREAD' and `SQL_THREAD' options to the statement to
name which of the threads to start.

An `UNTIL' clause may be added to specify that the slave should start
and run until the SQL thread reaches a given point in the master binary
logs or in the slave relay logs. When the SQL thread reaches that
point, it stops. If the `SQL_THREAD' option is specified in the
statement, it starts only the SQL thread. Otherwise, it starts both
slave threads. If the SQL thread is running, the `UNTIL' clause is
ignored and a warning is issued.

For an `UNTIL' clause, you must specify both a log filename and
position. Do not mix master and relay log options.

Any `UNTIL' condition is reset by a subsequent `STOP SLAVE' statement,
a `START SLAVE' statement that includes no `UNTIL' clause, or a server
restart.

The `UNTIL' clause can be useful for debugging replication, or to cause
replication to proceed until just before the point where you want to
avoid having the slave replicate a statement. For example, if an unwise
`DROP TABLE' statement was executed on the master, you can use `UNTIL'
to tell the slave to execute up to that point but no farther. To find
what the event is, use `mysqlbinlog' with the master logs or slave
relay logs, or by using a `SHOW BINLOG EVENTS' statement.

If you are using `UNTIL' to have the slave process replicated queries
in sections, it is recommended that you start the slave with the
`--skip-slave-start' option to prevent the SQL thread from running when
the slave server starts. It is probably best to use this option in an
option file rather than on the command line, so that an unexpected
server restart does not cause it to be forgotten.

The `SHOW SLAVE STATUS' statement includes output fields that display
the current values of the `UNTIL' condition.

In old versions of MySQL (before 4.0.5), this statement was called
`SLAVE START'. This usage is still accepted in MySQL 5.1 for backward
compatibility, but is deprecated.


File: manual.info,  Node: stop-slave,  Prev: start-slave,  Up: replication-slave-sql

12.6.2.8 `STOP SLAVE' Syntax
............................

     STOP SLAVE [THREAD_TYPE [, THREAD_TYPE] ... ]

     THREAD_TYPE: IO_THREAD | SQL_THREAD

Stops the slave threads. `STOP SLAVE' requires the `SUPER' privilege.

Like `START SLAVE', this statement may be used with the `IO_THREAD' and
`SQL_THREAD' options to name the thread or threads to be stopped.

In old versions of MySQL (before 4.0.5), this statement was called
`SLAVE STOP'. This usage is still accepted in MySQL 5.1 for backward
compatibility, but is deprecated.


File: manual.info,  Node: sql-syntax-prepared-statements,  Prev: sql-syntax-replication,  Up: sql-syntax

12.7 SQL Syntax for Prepared Statements
=======================================

* Menu:

* statement-repreparation::      Automatic Prepared Statement Repreparation

MySQL 5.1 provides support for server-side prepared statements. This
support takes advantage of the efficient client/server binary protocol
implemented in MySQL 4.1, provided that you use an appropriate client
programming interface. Candidate interfaces include the MySQL C API
client library (for C programs), MySQL Connector/J (for Java programs),
and MySQL Connector/NET. For example, the C API provides a set of
function calls that make up its prepared statement API. See *Note
c-api-prepared-statements::. Other language interfaces can provide
support for prepared statements that use the binary protocol by linking
in the C client library, one example being the `mysqli' extension
(http://php.net/mysqli), available in PHP 5.0 and later.

An alternative SQL interface to prepared statements is available.  This
interface is not as efficient as using the binary protocol through a
prepared statement API, but requires no programming because it is
available directly at the SQL level:

   * You can use it when no programming interface is available to you.

   * You can use it from any program that allows you to send SQL
     statements to the server to be executed, such as the `mysql'
     client program.

   * You can use it even if the client is using an old version of the
     client library. The only requirement is that you be able to
     connect to a server that is recent enough to support SQL syntax
     for prepared statements.

SQL syntax for prepared statements is intended to be used for
situations such as these:

   * You want to test how prepared statements work in your application
     before coding it.

   * An application has problems executing prepared statements and you
     want to determine interactively what the problem is.

   * You want to create a test case that describes a problem you are
     having with prepared statements, so that you can file a bug report.

   * You need to use prepared statements but do not have access to a
     programming API that supports them.

SQL syntax for prepared statements is based on three SQL statements:

   * `PREPARE STMT_NAME FROM PREPARABLE_STMT'

     The `PREPARE' statement prepares a statement and assigns it a
     name, STMT_NAME, by which to refer to the statement later.
     Statement names are not case sensitive. PREPARABLE_STMT is either
     a string literal or a user variable that contains the text of the
     statement. The text must represent a single SQL statement, not
     multiple statements. Within the statement, ``?'' characters can be
     used as parameter markers to indicate where data values are to be
     bound to the query later when you execute it. The ``?'' characters
     should not be enclosed within quotes, even if you intend to bind
     them to string values. Parameter markers can be used only where
     data values should appear, not for SQL keywords, identifiers, and
     so forth.

     If a prepared statement with the given name already exists, it is
     deallocated implicitly before the new statement is prepared.  This
     means that if the new statement contains an error and cannot be
     prepared, an error is returned and no statement with the given
     name exists.

     The scope of a prepared statement is the client session within
     which it is created. Other clients cannot see it.

   * `EXECUTE STMT_NAME [USING @VAR_NAME [, @VAR_NAME] ...]'

     After preparing a statement, you execute it with an `EXECUTE'
     statement that refers to the prepared statement name. If the
     prepared statement contains any parameter markers, you must supply
     a `USING' clause that lists user variables containing the values
     to be bound to the parameters. Parameter values can be supplied
     only by user variables, and the `USING' clause must name exactly
     as many variables as the number of parameter markers in the
     statement.

     You can execute a given prepared statement multiple times, passing
     different variables to it or setting the variables to different
     values before each execution.

   * `{DEALLOCATE | DROP} PREPARE STMT_NAME'

     To deallocate a prepared statement, use the `DEALLOCATE PREPARE'
     statement. Attempting to execute a prepared statement after
     deallocating it results in an error.

A prepared statement is specific to the connection in which it was
created. If you terminate a client session without deallocating a
previously prepared statement, the server deallocates it automatically.

A prepared statement is also global to the connection. If you create a
prepared statement within a stored routine, it is not deallocated when
the stored routine ends.

To guard against too many prepared statements being created
simultaneously, the `max_prepared_stmt_count' system variable can be
set.

The following SQL statements can be used in prepared statements: `ALTER
TABLE', `COMMIT', `CREATE INDEX', `CREATE TABLE', `DELETE', `DO', `DROP
INDEX', `DROP TABLE', `INSERT', `RENAME TABLE', `REPLACE', `SELECT',
`SET', `UPDATE', and most `SHOW' statements.

As of MySQL 5.1.10, the following additional statements are supported:

     ANALYZE TABLE
     OPTIMIZE TABLE
     REPAIR TABLE

As of MySQL 5.1.12, the following additional statements are supported:

     CACHE INDEX
     CHANGE MASTER
     CHECKSUM {TABLE | TABLES}
     {CREATE | DROP} DATABASE
     {CREATE | RENAME | DROP} USER
     FLUSH {TABLE | TABLES | TABLES WITH READ LOCK | HOSTS | PRIVILEGES
       | LOGS | STATUS | MASTER | SLAVE | DES_KEY_FILE | USER_RESOURCES}
     GRANT
     REVOKE
     KILL
     LOAD INDEX INTO CACHE
     RESET {MASTER | SLAVE | QUERY CACHE}
     SHOW BINLOG EVENTS
     SHOW CREATE {PROCEDURE | FUNCTION | EVENT | TABLE | VIEW}
     SHOW {AUTHORS | CONTRIBUTORS | WARNINGS | ERRORS}
     SHOW {MASTER | BINARY} LOGS
     SHOW {MASTER | SLAVE} STATUS
     SLAVE {START | STOP}
     INSTALL PLUGIN
     UNINSTALL PLUGIN

Other statements are not yet supported.

Statements not allowed in SQL prepared statements are generally also
not permitted in stored routines. Any exceptions to this rule are noted
in *Note stored-procedures::.

The following examples show two equivalent ways of preparing a
statement that computes the hypotenuse of a triangle given the lengths
of the two sides.

The first example shows how to create a prepared statement by using a
string literal to supply the text of the statement:

     mysql> PREPARE stmt1 FROM 'SELECT SQRT(POW(?,2) + POW(?,2)) AS hypotenuse';
     mysql> SET @a = 3;
     mysql> SET @b = 4;
     mysql> EXECUTE stmt1 USING @a, @b;
     +------------+
     | hypotenuse |
     +------------+
     |          5 |
     +------------+
     mysql> DEALLOCATE PREPARE stmt1;

The second example is similar, but supplies the text of the statement
as a user variable:

     mysql> SET @s = 'SELECT SQRT(POW(?,2) + POW(?,2)) AS hypotenuse';
     mysql> PREPARE stmt2 FROM @s;
     mysql> SET @a = 6;
     mysql> SET @b = 8;
     mysql> EXECUTE stmt2 USING @a, @b;
     +------------+
     | hypotenuse |
     +------------+
     |         10 |
     +------------+
     mysql> DEALLOCATE PREPARE stmt2;

Here is an additional example which demonstrates how to choose the
table on which to perform a query at run time, by storing the name of
the table as a user variable:

     mysql> USE test;
     mysql> CREATE TABLE t1 (a INT NOT NULL);
     mysql> INSERT INTO t1 VALUES (4), (8), (11), (32), (80);

     mysql> SET @table = 't1';
     mysql> SET @s = CONCAT('SELECT * FROM ', @table);

     mysql> PREPARE stmt3 FROM @s;
     mysql> EXECUTE stmt3;
     +----+
     | a  |
     +----+
     |  4 |
     |  8 |
     | 11 |
     | 32 |
     | 80 |
     +----+

     mysql> DEALLOCATE PREPARE stmt3;

Placeholders can be used for the arguments of the `LIMIT' clause when
using prepared statements. See *Note select::.

SQL syntax for prepared statements cannot be used in nested fashion.
That is, a statement passed to `PREPARE' cannot itself be a `PREPARE',
`EXECUTE', or `DEALLOCATE PREPARE' statement.

SQL syntax for prepared statements is distinct from using prepared
statement API calls. For example, you cannot use the *Note
`mysql_stmt_prepare()': mysql-stmt-prepare. C API function to prepare a
`PREPARE', `EXECUTE', or `DEALLOCATE PREPARE' statement.

SQL syntax for prepared statements can be used within stored
procedures, but not in stored functions or triggers. However, a cursor
cannot be used for a dynamic statement that is prepared and executed
with `PREPARE' and `EXECUTE'. The statement for a cursor is checked at
cursor creation time, so the statement cannot be dynamic.

SQL syntax for prepared statements does not support multi-statements
(that is, multiple statements within a single string separated by ``;''
characters).

Before MySQL 5.1.17, prepared statements do not use the query cache.
As of 5.1.17, prepared statements use the query cache under the
conditions described in *Note query-cache-how::.


File: manual.info,  Node: statement-repreparation,  Prev: sql-syntax-prepared-statements,  Up: sql-syntax-prepared-statements

12.7.1 Automatic Prepared Statement Repreparation
-------------------------------------------------

As of MySQL 5.1.25, metadata changes to tables or views referred to by
prepared statements are detected and cause automatic repreparation of
the statement when it is next executed. This applies to prepared
statements processed at the SQL level (using the `PREPARE' statement)
and those processed using the binary client-server protocol (using the
*Note `mysql_stmt_prepare()': mysql-stmt-prepare. C API function).

Metadata changes occur for DDL statements such as those that create,
drop, alter, rename, or truncate tables, or that analyze, optimize, or
repair tables. Repreparation also occurs after referenced tables or
views are flushed from the table definition cache, either implicitly to
make room for new entries in the cache, or explicitly due to `FLUSH
TABLES'.

Repreparation is automatic, but to the extent that it occurs,
performance of prepared statements is diminished.

When a statement is reprepared, the default database and SQL mode that
were in effect for the original preparation are used.

Table content changes (for example, with `INSERT' or `UPDATE') do not
cause repreparation, nor do `SELECT' statements.

An incompatibility with previous versions of MySQL is that a prepared
statement may return a different set of columns or different column
types from one execution to the next. For example, if the prepared
statement is `SELECT * FROM t1', altering `t1' to contain a different
number of columns causes the next execution to return a number of
columns different from the previous execution.

Older versions of the client library cannot handle this change in
behavior. For applications that use prepared statements with a server
that performs automatic repreparation, an upgrade to the new client
library is strongly recommended.

The `Com_stmt_reprepare' status variable tracks the number of
repreparations.


File: manual.info,  Node: storage-engines,  Next: ha-overview,  Prev: sql-syntax,  Up: Top

13 Storage Engines
******************

* Menu:

* pluggable-storage-overview::   Overview of MySQL Storage Engine Architecture
* storage-engine-overview::      Supported Storage Engines
* storage-engine-setting::       Setting the Storage Engine
* myisam-storage-engine::        The `MyISAM' Storage Engine
* innodb::                       The `InnoDB' Storage Engine
* merge-storage-engine::         The `MERGE' Storage Engine
* memory-storage-engine::        The `MEMORY' (`HEAP') Storage Engine
* example-storage-engine::       The `EXAMPLE' Storage Engine
* federated-storage-engine::     The `FEDERATED' Storage Engine
* archive-storage-engine::       The `ARCHIVE' Storage Engine
* csv-storage-engine::           The `CSV' Storage Engine
* blackhole-storage-engine::     The `BLACKHOLE' Storage Engine

MySQL supports several storage engines that act as handlers for
different table types. MySQL storage engines include both those that
handle transaction-safe tables and those that handle
non-transaction-safe tables.

With MySQL 5.1, MySQL AB has introduced a new pluggable storage engine
architecture that allows storage engines to be loaded into and unloaded
from a running MySQL server.

This chapter describes each of the MySQL storage engines except for
`NDBCLUSTER', which is covered in *Note mysql-cluster::. It also
contains a description of the pluggable storage engine architecture (see
*Note pluggable-storage-overview::).

For answers to some commonly asked questions about MySQL storage
engines, see *Note faqs-storage-engines::.


File: manual.info,  Node: pluggable-storage-overview,  Next: storage-engine-overview,  Prev: storage-engines,  Up: storage-engines

13.1 Overview of MySQL Storage Engine Architecture
==================================================

* Menu:

* pluggable-storage-common-layer::  The Common Database Server Layer
* pluggable-storage::            Pluggable Storage Engine Architecture

The MySQL pluggable storage engine architecture allows a database
professional to select a specialized storage engine for a particular
application need while being completely shielded from the need to
manage any specific application coding requirements.  The MySQL server
architecture isolates the application programmer and DBA from all of
the low-level implementation details at the storage level, providing a
consistent and easy application model and API. Thus, although there are
different capabilities across different storage engines, the
application is shielded from these differences.

The MySQL pluggable storage engine architecture is shown in *Note
figure-storage-engine-architecture::.

FIGURE GOES HERE: The MySQL architecture using pluggable storage engines

The pluggable storage engine architecture provides a standard set of
management and support services that are common among all underlying
storage engines. The storage engines themselves are the components of
the database server that actually perform actions on the underlying
data that is maintained at the physical server level.

This efficient and modular architecture provides huge benefits for
those wishing to specifically target a particular application need --
such as data warehousing, transaction processing, or high availability
situations -- while enjoying the advantage of utilizing a set of
interfaces and services that are independent of any one storage engine.

The application programmer and DBA interact with the MySQL database
through Connector APIs and service layers that are above the storage
engines. If application changes bring about requirements that demand
the underlying storage engine change, or that one or more additional
storage engines be added to support new needs, no significant coding or
process changes are required to make things work. The MySQL server
architecture shields the application from the underlying complexity of
the storage engine by presenting a consistent and easy-to-use API that
applies across storage engines.


File: manual.info,  Node: pluggable-storage-common-layer,  Next: pluggable-storage,  Prev: pluggable-storage-overview,  Up: pluggable-storage-overview

13.1.1 The Common Database Server Layer
---------------------------------------

A MySQL pluggable storage engine is the component in the MySQL database
server that is responsible for performing the actual data I/O
operations for a database as well as enabling and enforcing certain
feature sets that target a specific application need. A major benefit
of using specific storage engines is that you are only delivered the
features needed for a particular application, and therefore you have
less system overhead in the database, with the end result being more
efficient and higher database performance. This is one of the reasons
that MySQL has always been known to have such high performance,
matching or beating proprietary monolithic databases in industry
standard benchmarks.

From a technical perspective, what are some of the unique supporting
infrastructure components that are in a storage engine? Some of the key
feature differentiations include:

   * _Concurrency_ -- some applications have more granular lock
     requirements (such as row-level locks) than others. Choosing the
     right locking strategy can reduce overhead and therefore improve
     overall performance.  This area also includes support for
     capabilities such as multi-version concurrency control or
     `snapshot' read.

   * _Transaction Support_ -- Not every application needs transactions,
     but for those that do, there are very well defined requirements
     such as ACID compliance and more.

   * _Referential Integrity_ -- The need to have the server enforce
     relational database referential integrity through DDL defined
     foreign keys.

   * _Physical Storage_ -- This involves everything from the overall
     page size for tables and indexes as well as the format used for
     storing data to physical disk.

   * _Index Support_ -- Different application scenarios tend to benefit
     from different index strategies. Each storage engine generally has
     its own indexing methods, although some (such as B-tree indexes)
     are common to nearly all engines.

   * _Memory Caches_ -- Different applications respond better to some
     memory caching strategies than others, so although some memory
     caches are common to all storage engines (such as those used for
     user connections or MySQL's high-speed Query Cache), others are
     uniquely defined only when a particular storage engine is put in
     play.

   * _Performance Aids_ -- This includes multiple I/O threads for
     parallel operations, thread concurrency, database checkpointing,
     bulk insert handling, and more.

   * _Miscellaneous Target Features_ -- This may include support for
     geospatial operations, security restrictions for certain data
     manipulation operations, and other similar features.

Each set of the pluggable storage engine infrastructure components are
designed to offer a selective set of benefits for a particular
application. Conversely, avoiding a set of component features helps
reduce unnecessary overhead. It stands to reason that understanding a
particular application's set of requirements and selecting the proper
MySQL storage engine can have a dramatic impact on overall system
efficiency and performance.


File: manual.info,  Node: pluggable-storage,  Prev: pluggable-storage-common-layer,  Up: pluggable-storage-overview

13.1.2 Pluggable Storage Engine Architecture
--------------------------------------------

With MySQL 5.1, MySQL AB has introduced a new pluggable storage engine
architecture that allows storage engines to be loaded into and unloaded
from a running MySQL server.

*Plugging in a Storage Engine*

Before a storage engine can be used, the storage engine plugin shared
library must be loaded into MySQL using the `INSTALL PLUGIN' statement.
For example, if the `EXAMPLE' engine plugin is named `ha_example' and
the shared library is named `ha_example.so', you load it with the
following statement:

     mysql> INSTALL PLUGIN ha_example SONAME 'ha_example.so';

To install a pluggable storage engine, the plugin file must be located
in the MySQL plugin directory, and the user issuing the `INSTALL
PLUGIN' statement must have `INSERT' privileges for the `mysql.plugin'
table.

The shared library must be located in the MySQL server plugin
directory, the location of which is given by the `plugin_dir' system
variable.

*Unplugging a Storage Engine*

To unplug a storage engine, use the `UNINSTALL PLUGIN' statement:

     mysql> UNINSTALL PLUGIN ha_example;

If you unplug a storage engine that is needed by existing tables, those
tables become inaccessible, but will still be present on disk (where
applicable). Ensure that there are no tables using a storage engine
before you unplug the storage engine.


File: manual.info,  Node: storage-engine-overview,  Next: storage-engine-setting,  Prev: pluggable-storage-overview,  Up: storage-engines

13.2 Supported Storage Engines
==============================

* Menu:

* storage-engine-choosing::      Choosing a Storage Engine
* storage-engine-compare-transactions::  Comparing Transaction and Non-Transaction Engines
* storage-engines-other::        Other Storage Engines

MySQL 5.1 supports the following storage engines:

   * *Note `MyISAM': myisam-storage-engine.  -- The default MySQL
     storage engine and the one that is used the most in Web, data
     warehousing, and other application environments. `MyISAM' is
     supported in all MySQL configurations, and is the default storage
     engine unless you have configured MySQL to use a different one by
     default.

   * *Note `InnoDB': innodb.  -- Used for transaction processing
     applications, and sports a number of features including ACID
     transaction support and foreign keys. `InnoDB' is included by
     default in all MySQL 5.1 binary distributions. In source
     distributions, you can enable or disable either engine by
     configuring MySQL as you like.

   * *Note `Memory': memory-storage-engine.  -- Stores all data in RAM
     for extremely fast access in environments that require quick
     lookups of reference and other like data. This engine was formerly
     known as the `HEAP' engine.

   * *Note `Merge': merge-storage-engine.  -- Allows a MySQL DBA or
     developer to logically group a series of identical `MyISAM' tables
     and reference them as one object. Good for VLDB environments such
     as data warehousing.

   * *Note `Archive': archive-storage-engine.  -- Provides the perfect
     solution for storing and retrieving large amounts of
     seldom-referenced historical, archived, or security audit
     information.

   * *Note `Federated': federated-storage-engine.  -- Offers the
     ability to link separate MySQL servers to create one logical
     database from many physical servers. Very good for distributed or
     data mart environments.

   * *Note `NDB': mysql-cluster.  -- The Clustered database engine that
     is particularly suited for applications with high performance
     lookup needs that also require the highest possible degree of
     uptime and availability.

   * *Note `CSV': csv-storage-engine.  -- The CSV storage engine stores
     data in text files using comma-separated values format. You can
     use the CSV engine to easily exchange data between other software
     and applications that can import and export in CSV format.

   * *Note `Blackhole': blackhole-storage-engine.  -- The Blackhole
     storage engine accepts but does not store data and retrievals
     always return an empty set. The functionality can be used in
     distributed database design where data is automatically
     replicated, but not stored locally.

   * *Note `Example': example-storage-engine.  -- The Example storage
     engine is `stub' engine that does nothing. You can create tables
     with this engine, but no data can be stored in them or retrieved
     from them. The purpose of this engine is to serve as an example in
     the MySQL source code that illustrates how to begin writing new
     storage engines. As such, it is primarily of interest to
     developers.

This chapter describes each of the MySQL storage engines except for
`NDBCLUSTER', which is covered in *Note mysql-cluster::.

It is important to remember that you are not restricted to using the
same storage engine for an entire server or schema: you can use a
different storage engine for each table in your schema.


File: manual.info,  Node: storage-engine-choosing,  Next: storage-engine-compare-transactions,  Prev: storage-engine-overview,  Up: storage-engine-overview

13.2.1 Choosing a Storage Engine
--------------------------------

The various storage engines provided with MySQL are designed with
different use-cases in mind. To use the pluggable storage architecture
effectively, it is good to have an idea of the benefits and drawbacks
of the various storage engines. The following table provides an
overview of some storage engines provided with MySQL:

*Feature*     *MyISAM*  *Memory*  *InnoDB*  *Archive* *NDB*
Storage       256TB     Yes       64TB      No        384EB
limits                                                
                                                      EB =
                                                      exabyte
                                                      (1024 *
                                                      1024
                                                      terabyte)
Transactions  No        No        Yes       No        Yes
Locking       Table     Table     Row       Row       Row
granularity                                           
MVCC          No        No        Yes       Yes       No
(snapshot                                             
read)                                                 
Geospatial    Yes       No        Yes       Yes       Yes
datatype                                              
support                                               
Geospatial    Yes       No        No        No        No
indexing                                              
support                                               
B-tree        Yes       Yes       Yes       No        Yes
indexes                                               
Hash indexes  No        Yes       No        No        Yes
Full-text     Yes       No        No        No        No
search                                                
indexes                                               
Clustered     No        No        Yes       No        No
indexes                                               
Data caches   No        N/A       Yes       No        Yes
Index caches  Yes       N/A       Yes       No        Yes
Compressed    Yes       No        No        Yes       No
data                                                  
              Compressed                              
              MyISAM                                  
              tables                                  
              are only                                
              supported                               
              when                                    
              using                                   
              the                                     
              compressed                              
              row                                     
              format.                                 
              Tables                                  
              using the                               
              compressed                              
              row                                     
              format                                  
              with                                    
              MyISAM                                  
              are read                                
              only.                                   
Encrypted     Yes       Yes       Yes       Yes       Yes
data                                                  
                                                      
Implemented                                           
in the                                                
server (via                                           
encryption                                            
functions),                                           
rather than                                           
in the                                                
storage                                               
engine.                                               
Cluster       No        No        No        No        Yes
database                                              
support                                               
Replication   Yes       Yes       Yes       Yes       Yes
support                                               
                                                      
Implemented                                           
in the                                                
server,                                               
rather than                                           
in the                                                
storage                                               
engine                                                
Foreign key   No        No        Yes       No        No
support                                               
Backup /      Yes       Yes       Yes       Yes       Yes
point-in-time                                         
recovery                                              
                                                      
Implemented                                           
in the                                                
server,                                               
rather than                                           
in the                                                
storage                                               
engine                                                
Query cache   Yes       Yes       Yes       Yes       Yes
support                                               
Update        Yes       Yes       Yes       Yes       Yes
statistics                                            
for data                                              
dictionary                                            


File: manual.info,  Node: storage-engine-compare-transactions,  Next: storage-engines-other,  Prev: storage-engine-choosing,  Up: storage-engine-overview

13.2.2 Comparing Transaction and Non-Transaction Engines
--------------------------------------------------------

Transaction-safe tables (TSTs) have several advantages over
non-transaction-safe tables (NTSTs):

   * They are safer. Even if MySQL crashes or you get hardware
     problems, you can get your data back, either by automatic recovery
     or from a backup plus the transaction log.

   * You can combine many statements and accept them all at the same
     time with the `COMMIT' statement (if autocommit is disabled).

   * You can execute `ROLLBACK' to ignore your changes (if autocommit
     is disabled).

   * If an update fails, all of your changes are reverted. (With
     non-transaction-safe tables, all changes that have taken place are
     permanent.)

   * Transaction-safe storage engines can provide better concurrency
     for tables that get many updates concurrently with reads.

You can combine transaction-safe and non-transaction-safe tables in the
same statements to get the best of both worlds. However, although MySQL
supports several transaction-safe storage engines, for best results,
you should not mix different storage engines within a transaction with
autocommit disabled. For example, if you do this, changes to
non-transaction-safe tables still are committed immediately and cannot
be rolled back. For information about this and other problems that can
occur in transactions that use mixed storage engines, see *Note
commit::.

Non-transaction-safe tables have several advantages of their own, all
of which occur because there is no transaction overhead:

   * Much faster

   * Lower disk space requirements

   * Less memory required to perform updates


File: manual.info,  Node: storage-engines-other,  Prev: storage-engine-compare-transactions,  Up: storage-engine-overview

13.2.3 Other Storage Engines
----------------------------

Other storage engines may be available from third parties and community
members that have used the Custom Storage Engine interface.

You can find more information on the list of third party storage
engines on the MySQL Forge Storage Engines
(http://forge.mysql.com/projects/search.php?t=tag&k=storage%20engine)
page.

*Note*:

Third party engines are not supported by MySQL. For further
information, documentation, installation guides, bug reporting or for
any help or assistance with these engines, please contact the developer
of the engine directly.

Third party engines that are known to be available include the
following; please see the MySQL Forge links provided for more
information:

   * *PrimeBase XT (PBXT)
     (http://forge.mysql.com/projects/project.php?id=43)* -- PBXT has
     been designed for modern, web-based, high concurrency environments.

   * *RitmarkFS (http://forge.mysql.com/projects/project.php?id=82)* --
     RitmarkFS allows you to access and manipulate the filesystem using
     SQL queries. RitmarkFS also supports filesystem replication and
     directory change tracking.

   * *Distributed Data Engine
     (http://forge.mysql.com/projects/project.php?id=91)* -- The
     Distributed Data Engine is an Open Source project that is
     dedicated to provide a Storage Engine for distributed data
     according to workload statistics.

   * *mdbtools (http://forge.mysql.com/projects/project.php?id=98)* --
     A pluggable storage engine that allows read-only access to
     Microsoft Access `.mdb' database files.

   * *solidDB for MySQL
     (http://forge.mysql.com/projects/project.php?id=139)* -- solidDB
     Storage Engine for MySQL is an open source, transactional storage
     engine for MySQL Server. It is designed for mission-critical
     implementations that require a robust, transactional database.
     solidDB Storage Engine for MySQL is a multi-threaded storage
     engine that supports full ACID compliance with all expected
     transaction isolation levels, row-level locking, and Multi-Version
     Concurrency Control (MVCC) with non-blocking reads and writes.

   * *BLOB Streaming Engine (MyBS) (http://www.blobstreaming.org/)* --
     The Scalable BLOB Streaming infrastructure for MySQL will
     transform MySQL into a scalable media server capable of streaming
     pictures, films, MP3 files and other binary and text objects
     (BLOBs) directly in and out of the database.

For more information on developing a customer storage engine that can
be used with the Pluggable Storage Engine Architecture, see Writing a
Custom Storage Engine
(http://forge.mysql.com/wiki/MySQL_Internals_Custom_Engine) on MySQL
Forge (http://forge.mysql.com/wiki).


File: manual.info,  Node: storage-engine-setting,  Next: myisam-storage-engine,  Prev: storage-engine-overview,  Up: storage-engines

13.3 Setting the Storage Engine
===============================

When you create a new table, you can specify which storage engine to
use by adding an `ENGINE' table option to the `CREATE TABLE' statement:

     CREATE TABLE t (i INT) ENGINE = INNODB;

If you omit the `ENGINE' or `TYPE' option, the default storage engine is
used. Normally, this is `MyISAM', but you can change it by using the
`--default-storage-engine' or `--default-table-type' server startup
option, or by setting the `default-storage-engine' or
`default-table-type' option in the `my.cnf' configuration file.

You can set the default storage engine to be used during the current
session by setting the `storage_engine' variable:

     SET storage_engine=MYISAM;

When MySQL is installed on Windows using the MySQL Configuration
Wizard, the `InnoDB' storage engine can be selected as the default
instead of `MyISAM'. See *Note mysql-config-wizard-database-usage::.

To convert a table from one storage engine to another, use an `ALTER
TABLE' statement that indicates the new engine:

     ALTER TABLE t ENGINE = MYISAM;

See *Note create-table::, and *Note alter-table::.

If you try to use a storage engine that is not compiled in or that is
compiled in but deactivated, MySQL instead creates a table using the
default storage engine, usually `MyISAM'. This behavior is convenient
when you want to copy tables between MySQL servers that support
different storage engines. (For example, in a replication setup, perhaps
your master server supports transactional storage engines for increased
safety, but the slave servers use only non-transactional storage
engines for greater speed.)

This automatic substitution of the default storage engine for
unavailable engines can be confusing for new MySQL users. A warning is
generated whenever a storage engine is automatically changed.

For new tables, MySQL always creates an `.frm' file to hold the table
and column definitions. The table's index and data may be stored in one
or more other files, depending on the storage engine. The server
creates the `.frm' file above the storage engine level.  Individual
storage engines create any additional files required for the tables
that they manage. If a table name contains special characters, the
names for the table files contain encoded versions of those characters
as described in *Note identifier-mapping::.

A database may contain tables of different types. That is, tables need
not all be created with the same storage engine.


File: manual.info,  Node: myisam-storage-engine,  Next: innodb,  Prev: storage-engine-setting,  Up: storage-engines

13.4 The `MyISAM' Storage Engine
================================

* Menu:

* myisam-start::                 `MyISAM' Startup Options
* key-space::                    Space Needed for Keys
* myisam-table-formats::         `MyISAM' Table Storage Formats
* myisam-table-problems::        `MyISAM' Table Problems

`MyISAM' is the default storage engine. It is based on the older `ISAM'
code but has many useful extensions. (Note that MySQL 5.1 does _not_
support `ISAM'.)

Each `MyISAM' table is stored on disk in three files. The files have
names that begin with the table name and have an extension to indicate
the file type. An `.frm' file stores the table format. The data file
has an `.MYD' (`MYData') extension. The index file has an `.MYI'
(`MYIndex') extension.

To specify explicitly that you want a `MyISAM' table, indicate that
with an `ENGINE' table option:

     CREATE TABLE t (i INT) ENGINE = MYISAM;

Normally, it is unnecessary to use `ENGINE' to specify the `MyISAM'
storage engine.  `MyISAM' is the default engine unless the default has
been changed. To ensure that `MyISAM' is used in situations where the
default might have been changed, include the `ENGINE' option explicitly.

You can check or repair `MyISAM' tables with the `mysqlcheck' client or
`myisamchk' utility. You can also compress `MyISAM' tables with
`myisampack' to take up much less space. See *Note mysqlcheck::, *Note
crash-recovery::, and *Note myisampack::.

`MyISAM' tables have the following characteristics:

   * All data values are stored with the low byte first. This makes the
     data machine and operating system independent. The only
     requirements for binary portability are that the machine uses
     two's-complement signed integers and IEEE floating-point format.
     These requirements are widely used among mainstream machines.
     Binary compatibility might not be applicable to embedded systems,
     which sometimes have peculiar processors.

     There is no significant speed penalty for storing data low byte
     first; the bytes in a table row normally are unaligned and it
     takes little more processing to read an unaligned byte in order
     than in reverse order. Also, the code in the server that fetches
     column values is not time critical compared to other code.

   * All numeric key values are stored with the high byte first to
     allow better index compression.

   * Large files (up to 63-bit file length) are supported on
     filesystems and operating systems that support large files.

   * There is a limit of 2^32 (~4.295E+09) rows in a `MyISAM' table. If
     you build MySQL with the `--with-big-tables' option, the row
     limitation is increased to (2^32)^2 (1.844E+19) rows. See *Note
     configure-options::.  Binary distributions for Unix and Linux are
     built with this option.

   * The maximum number of indexes per `MyISAM' table is 64. This can
     be changed by recompiling. Beginning with MySQL 5.1.4, you can
     configure the build by invoking `configure' with the
     `--with-max-indexes=N' option, where N is the maximum number of
     indexes to permit per `MyISAM' table.  N must be less than or
     equal to 128.  Before MySQL 5.1.4, you must change the source.

     The maximum number of columns per index is 16.

   * The maximum key length is 1000 bytes. This can also be changed by
     changing the source and recompiling. For the case of a key longer
     than 250 bytes, a larger key block size than the default of 1024
     bytes is used.

   * When rows are inserted in sorted order (as when you are using an
     `AUTO_INCREMENT' column), the index tree is split so that the high
     node only contains one key. This improves space utilization in the
     index tree.

   * Internal handling of one `AUTO_INCREMENT' column per table is
     supported. `MyISAM' automatically updates this column for `INSERT'
     and `UPDATE' operations. This makes `AUTO_INCREMENT' columns
     faster (at least 10%).  Values at the top of the sequence are not
     reused after being deleted. (When an `AUTO_INCREMENT' column is
     defined as the last column of a multiple-column index, reuse of
     values deleted from the top of a sequence does occur.) The
     `AUTO_INCREMENT' value can be reset with `ALTER TABLE' or
     `myisamchk'.

   * Dynamic-sized rows are much less fragmented when mixing deletes
     with updates and inserts. This is done by automatically combining
     adjacent deleted blocks and by extending blocks if the next block
     is deleted.

   * `MyISAM' supports concurrent inserts: If a table has no free
     blocks in the middle of the data file, you can `INSERT' new rows
     into it at the same time that other threads are reading from the
     table. A free block can occur as a result of deleting rows or an
     update of a dynamic length row with more data than its current
     contents. When all free blocks are used up (filled in), future
     inserts become concurrent again. See *Note concurrent-inserts::.

   * You can put the data file and index file in different directories
     on different physical devices to get more speed with the `DATA
     DIRECTORY' and `INDEX DIRECTORY' table options to `CREATE TABLE'.
     See *Note create-table::.

   * `BLOB' and `TEXT' columns can be indexed.

   * `NULL' values are allowed in indexed columns.  This takes 0-1
     bytes per key.

   * Each character column can have a different character set. See
     *Note charset::.

   * There is a flag in the `MyISAM' index file that indicates whether
     the table was closed correctly. If `mysqld' is started with the
     `--myisam-recover' option, `MyISAM' tables are automatically
     checked when opened, and are repaired if the table wasn't closed
     properly.

   * `myisamchk' marks tables as checked if you run it with the
     `--update-state' option.  `myisamchk --fast' checks only those
     tables that don't have this mark.

   * `myisamchk --analyze' stores statistics for portions of keys, as
     well as for entire keys.

   * `myisampack' can pack `BLOB' and `VARCHAR' columns.

`MyISAM' also supports the following features:

   * Support for a true `VARCHAR' type; a `VARCHAR' column starts with
     a length stored in one or two bytes.

   * Tables with `VARCHAR' columns may have fixed or dynamic row length.

   * The sum of the lengths of the `VARCHAR' and `CHAR' columns in a
     table may be up to 64KB.

   * Arbitrary length `UNIQUE' constraints.

*Additional resources*

   * A forum dedicated to the `MyISAM' storage engine is available at
     `http://forums.mysql.com/list.php?21'.


File: manual.info,  Node: myisam-start,  Next: key-space,  Prev: myisam-storage-engine,  Up: myisam-storage-engine

13.4.1 `MyISAM' Startup Options
-------------------------------

The following options to `mysqld' can be used to change the behavior of
`MyISAM' tables. For additional information, see *Note server-options::.

*Name*                        *Cmd-Line*                                                 *Option file*                                              *System Var*                                               *Status Var*                                               *Var Scope*                                                *Dynamic*
bulk_insert_buffer_size       Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
concurrent_insert             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
delay-key-write               Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: delay_key_write                                                                                                                       Yes                                                                                                                   Global                                                     Yes
have_rtree_keys                                                                                                                                     Yes                                                                                                                   Global                                                     No
key_buffer_size               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
log-isam                      Yes                                                        Yes                                                                                                                                                                                                                                         
myisam_block_size             Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
myisam_data_pointer_size      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
myisam_max_sort_file_size     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
myisam-recover                Yes                                                        Yes                                                                                                                                                                                                                                         
myisam_recover_options                                                                                                                              Yes                                                                                                                   Global                                                     No
myisam_repair_threads         Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
myisam_sort_buffer_size       Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
myisam_stats_method           Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
myisam_use_mmap               Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
skip-concurrent-insert        Yes                                                        Yes                                                                                                                                                                                                                                         
- _Variable_:                                                                                                                                                                                                                                                                                                                        
concurrent_insert                                                                                                                                                                                                                                                                                                                    
tmp_table_size                Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes

   * `--myisam-recover=MODE'

     Set the mode for automatic recovery of crashed `MyISAM' tables.

   * `--delay-key-write=ALL'

     Don't flush key buffers between writes for any `MyISAM' table.

     *Note*:

     If you do this, you should not access `MyISAM' tables from another
     program (such as from another MySQL server or with `myisamchk')
     when the tables are in use.  Doing so risks index corruption. Using
     `--external-locking' does not eliminate this risk.

The following system variables affect the behavior of `MyISAM' tables.
For additional information, see *Note server-system-variables::.

   * `bulk_insert_buffer_size'

     The size of the tree cache used in bulk insert optimization.

     *Note*:

     This is a limit _per thread_!

   * `myisam_max_sort_file_size'

     The maximum size of the temporary file that MySQL is allowed to
     use while re-creating a `MyISAM' index (during `REPAIR TABLE',
     `ALTER TABLE', or `LOAD DATA INFILE'). If the file size would be
     larger than this value, the index is created using the key cache
     instead, which is slower. The value is given in bytes.

   * `myisam_sort_buffer_size'

     Set the size of the buffer used when recovering tables.

Automatic recovery is activated if you start `mysqld' with the
`--myisam-recover' option. In this case, when the server opens a
`MyISAM' table, it checks whether the table is marked as crashed or
whether the open count variable for the table is not 0 and you are
running the server with external locking disabled. If either of these
conditions is true, the following happens:

   * The server checks the table for errors.

   * If the server finds an error, it tries to do a fast table repair
     (with sorting and without re-creating the data file).

   * If the repair fails because of an error in the data file (for
     example, a duplicate-key error), the server tries again, this time
     re-creating the data file.

   * If the repair still fails, the server tries once more with the old
     repair option method (write row by row without sorting).  This
     method should be able to repair any type of error and has low disk
     space requirements.

MySQL Enterprise

Subscribers to MySQL Enterprise Monitor receive notification if the
`--myisam-recover' option has not been set.  For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

If the recovery wouldn't be able to recover all rows from previously
completed statements and you didn't specify `FORCE' in the value of the
`--myisam-recover' option, automatic repair aborts with an error
message in the error log:

     Error: Couldn't repair table: test.g00pages

If you specify `FORCE', a warning like this is written instead:

     Warning: Found 344 of 354 rows when repairing ./test/g00pages

Note that if the automatic recovery value includes `BACKUP', the
recovery process creates files with names of the form
`TBL_NAME-DATETIME.BAK'.  You should have a `cron' script that
automatically moves these files from the database directories to backup
media.


File: manual.info,  Node: key-space,  Next: myisam-table-formats,  Prev: myisam-start,  Up: myisam-storage-engine

13.4.2 Space Needed for Keys
----------------------------

`MyISAM' tables use B-tree indexes. You can roughly calculate the size
for the index file as `(key_length+4)/0.67', summed over all keys. This
is for the worst case when all keys are inserted in sorted order and
the table doesn't have any compressed keys.

String indexes are space compressed. If the first index part is a
string, it is also prefix compressed. Space compression makes the index
file smaller than the worst-case figure if a string column has a lot of
trailing space or is a `VARCHAR' column that is not always used to the
full length. Prefix compression is used on keys that start with a
string. Prefix compression helps if there are many strings with an
identical prefix.

In `MyISAM' tables, you can also prefix compress numbers by specifying
the `PACK_KEYS=1' table option when you create the table. Numbers are
stored with the high byte first, so this helps when you have many
integer keys that have an identical prefix.


File: manual.info,  Node: myisam-table-formats,  Next: myisam-table-problems,  Prev: key-space,  Up: myisam-storage-engine

13.4.3 `MyISAM' Table Storage Formats
-------------------------------------

* Menu:

* static-format::                Static (Fixed-Length) Table Characteristics
* dynamic-format::               Dynamic Table Characteristics
* compressed-format::            Compressed Table Characteristics

`MyISAM' supports three different storage formats. Two of them, fixed
and dynamic format, are chosen automatically depending on the type of
columns you are using. The third, compressed format, can be created
only with the `myisampack' utility (see *Note myisampack::).

When you use `CREATE TABLE' or `ALTER TABLE' for a table that has no
`BLOB' or `TEXT' columns, you can force the table format to `FIXED' or
`DYNAMIC' with the `ROW_FORMAT' table option.

See *Note create-table::, for information about `ROW_FORMAT'.

You can decompress (unpack) compressed `MyISAM' tables using `myisamchk
`--unpack''; see *Note myisamchk::, for more information.


File: manual.info,  Node: static-format,  Next: dynamic-format,  Prev: myisam-table-formats,  Up: myisam-table-formats

13.4.3.1 Static (Fixed-Length) Table Characteristics
....................................................

Static format is the default for `MyISAM' tables. It is used when the
table contains no variable-length columns (`VARCHAR', `VARBINARY',
`BLOB', or `TEXT'). Each row is stored using a fixed number of bytes.

Of the three `MyISAM' storage formats, static format is the simplest
and most secure (least subject to corruption). It is also the fastest
of the on-disk formats due to the ease with which rows in the data file
can be found on disk: To look up a row based on a row number in the
index, multiply the row number by the row length to calculate the row
position. Also, when scanning a table, it is very easy to read a
constant number of rows with each disk read operation.

The security is evidenced if your computer crashes while the MySQL
server is writing to a fixed-format `MyISAM' file. In this case,
`myisamchk' can easily determine where each row starts and ends, so it
can usually reclaim all rows except the partially written one. Note
that `MyISAM' table indexes can always be reconstructed based on the
data rows.

*Note*:

Fixed-length row format is only available for tables without `BLOB' or
`TEXT' columns.  Creating a table with these columns with an explicit
`ROW_FORMAT' clause will not raise an error or warning; the format
specification will be ignored.

Static-format tables have these characteristics:

   * `CHAR' and `VARCHAR' columns are space-padded to the specified
     column width, although the column type is not altered.  `BINARY'
     and `VARBINARY' columns are padded with `0x00' bytes to the column
     width.

   * Very quick.

   * Easy to cache.

   * Easy to reconstruct after a crash, because rows are located in
     fixed positions.

   * Reorganization is unnecessary unless you delete a huge number of
     rows and want to return free disk space to the operating system.
     To do this, use `OPTIMIZE TABLE' or `myisamchk -r'.

   * Usually require more disk space than dynamic-format tables.


File: manual.info,  Node: dynamic-format,  Next: compressed-format,  Prev: static-format,  Up: myisam-table-formats

13.4.3.2 Dynamic Table Characteristics
......................................

Dynamic storage format is used if a `MyISAM' table contains any
variable-length columns (`VARCHAR', `VARBINARY', `BLOB', or `TEXT'), or
if the table was created with the `ROW_FORMAT=DYNAMIC' table option.

Dynamic format is a little more complex than static format because each
row has a header that indicates how long it is. A row can become
fragmented (stored in non-contiguous pieces) when it is made longer as
a result of an update.

You can use `OPTIMIZE TABLE' or `myisamchk -r' to defragment a table.
If you have fixed-length columns that you access or change frequently
in a table that also contains some variable-length columns, it might be
a good idea to move the variable-length columns to other tables just to
avoid fragmentation.

Dynamic-format tables have these characteristics:

   * All string columns are dynamic except those with a length less
     than four.

   * Each row is preceded by a bitmap that indicates which columns
     contain the empty string (for string columns) or zero (for numeric
     columns). Note that this does not include columns that contain
     `NULL' values. If a string column has a length of zero after
     trailing space removal, or a numeric column has a value of zero,
     it is marked in the bitmap and not saved to disk. Non-empty
     strings are saved as a length byte plus the string contents.

   * Much less disk space usually is required than for fixed-length
     tables.

   * Each row uses only as much space as is required. However, if a row
     becomes larger, it is split into as many pieces as are required,
     resulting in row fragmentation. For example, if you update a row
     with information that extends the row length, the row becomes
     fragmented. In this case, you may have to run `OPTIMIZE TABLE' or
     `myisamchk -r' from time to time to improve performance. Use
     `myisamchk -ei' to obtain table statistics.

   * More difficult than static-format tables to reconstruct after a
     crash, because rows may be fragmented into many pieces and links
     (fragments) may be missing.

   * The expected row length for dynamic-sized rows is calculated using
     the following expression:

          3
          + (NUMBER OF COLUMNS + 7) / 8
          + (NUMBER OF CHAR COLUMNS)
          + (PACKED SIZE OF NUMERIC COLUMNS)
          + (LENGTH OF STRINGS)
          + (NUMBER OF NULL COLUMNS + 7) / 8

     There is a penalty of 6 bytes for each link. A dynamic row is
     linked whenever an update causes an enlargement of the row. Each
     new link is at least 20 bytes, so the next enlargement probably
     goes in the same link. If not, another link is created. You can
     find the number of links using `myisamchk -ed'. All links may be
     removed with `OPTIMIZE TABLE' or `myisamchk -r'.


File: manual.info,  Node: compressed-format,  Prev: dynamic-format,  Up: myisam-table-formats

13.4.3.3 Compressed Table Characteristics
.........................................

Compressed storage format is a read-only format that is generated with
the `myisampack' tool.  Compressed tables can be uncompressed with
`myisamchk'.

Compressed tables have the following characteristics:

   * Compressed tables take very little disk space. This minimizes disk
     usage, which is helpful when using slow disks (such as CD-ROMs).

   * Each row is compressed separately, so there is very little access
     overhead. The header for a row takes up one to three bytes
     depending on the biggest row in the table. Each column is
     compressed differently. There is usually a different Huffman tree
     for each column. Some of the compression types are:

        * Suffix space compression.

        * Prefix space compression.

        * Numbers with a value of zero are stored using one bit.

        * If values in an integer column have a small range, the column
          is stored using the smallest possible type. For example, a
          `BIGINT' column (eight bytes) can be stored as a `TINYINT'
          column (one byte) if all its values are in the range from
          `-128' to `127'.

        * If a column has only a small set of possible values, the data
          type is converted to `ENUM'.

        * A column may use any combination of the preceding compression
          types.

   * Can be used for fixed-length or dynamic-length rows.

*Note*:

While a compressed table is read only, and you cannot therefore update
or add rows in the table, DDL (Data Definition Language) operations are
still valid. For example, you may still use `DROP' to drop the table,
and `TRUNCATE' to empty the table.


File: manual.info,  Node: myisam-table-problems,  Prev: myisam-table-formats,  Up: myisam-storage-engine

13.4.4 `MyISAM' Table Problems
------------------------------

* Menu:

* corrupted-myisam-tables::      Corrupted `MyISAM' Tables
* myisam-table-close::           Problems from Tables Not Being Closed Properly

The file format that MySQL uses to store data has been extensively
tested, but there are always circumstances that may cause database
tables to become corrupted. The following discussion describes how this
can happen and how to handle it.


File: manual.info,  Node: corrupted-myisam-tables,  Next: myisam-table-close,  Prev: myisam-table-problems,  Up: myisam-table-problems

13.4.4.1 Corrupted `MyISAM' Tables
..................................

Even though the `MyISAM' table format is very reliable (all changes to
a table made by an SQL statement are written before the statement
returns), you can still get corrupted tables if any of the following
events occur:

   * The `mysqld' process is killed in the middle of a write.

   * An unexpected computer shutdown occurs (for example, the computer
     is turned off).

   * Hardware failures.

   * You are using an external program (such as `myisamchk') to modify
     a table that is being modified by the server at the same time.

   * A software bug in the MySQL or `MyISAM' code.

Typical symptoms of a corrupt table are:

   * You get the following error while selecting data from the table:

          Incorrect key file for table: '...'. Try to repair it

   * Queries don't find rows in the table or return incomplete results.

You can check the health of a `MyISAM' table using the `CHECK TABLE'
statement, and repair a corrupted `MyISAM' table with `REPAIR TABLE'.
When `mysqld' is not running, you can also check or repair a table with
the `myisamchk' command. See *Note check-table::, *Note repair-table::,
and *Note myisamchk::.

If your tables become corrupted frequently, you should try to determine
why this is happening. The most important thing to know is whether the
table became corrupted as a result of a server crash. You can verify
this easily by looking for a recent `restarted mysqld' message in the
error log. If there is such a message, it is likely that table
corruption is a result of the server dying. Otherwise, corruption may
have occurred during normal operation. This is a bug. You should try to
create a reproducible test case that demonstrates the problem. See
*Note crashing::, and MySQL Internals: Porting
(http://forge.mysql.com/wiki/MySQL_Internals_Porting).

MySQL Enterprise

Find out about problems before they occur. Subscribe to the MySQL
Enterprise Monitor for expert advice about the state of your servers.
For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: myisam-table-close,  Prev: corrupted-myisam-tables,  Up: myisam-table-problems

13.4.4.2 Problems from Tables Not Being Closed Properly
.......................................................

Each `MyISAM' index file (`.MYI' file) has a counter in the header that
can be used to check whether a table has been closed properly. If you
get the following warning from `CHECK TABLE' or `myisamchk', it means
that this counter has gone out of sync:

     clients are using or haven't closed the table properly

This warning doesn't necessarily mean that the table is corrupted, but
you should at least check the table.

The counter works as follows:

   * The first time a table is updated in MySQL, a counter in the
     header of the index files is incremented.

   * The counter is not changed during further updates.

   * When the last instance of a table is closed (because a `FLUSH
     TABLES' operation was performed or because there is no room in the
     table cache), the counter is decremented if the table has been
     updated at any point.

   * When you repair the table or check the table and it is found to be
     okay, the counter is reset to zero.

   * To avoid problems with interaction with other processes that might
     check the table, the counter is not decremented on close if it was
     zero.

In other words, the counter can become incorrect only under these
conditions:

   * A `MyISAM' table is copied without first issuing `LOCK TABLES' and
     `FLUSH TABLES'.

   * MySQL has crashed between an update and the final close.  (Note
     that the table may still be okay, because MySQL always issues
     writes for everything between each statement.)

   * A table was modified by `myisamchk --recover' or `myisamchk
     --update-state' at the same time that it was in use by `mysqld'.

   * Multiple `mysqld' servers are using the table and one server
     performed a `REPAIR TABLE' or `CHECK TABLE' on the table while it
     was in use by another server. In this setup, it is safe to use
     `CHECK TABLE', although you might get the warning from other
     servers. However, `REPAIR TABLE' should be avoided because when
     one server replaces the data file with a new one, this is not
     known to the other servers.

     In general, it is a bad idea to share a data directory among
     multiple servers. See *Note multiple-servers::, for additional
     discussion.


File: manual.info,  Node: innodb,  Next: merge-storage-engine,  Prev: myisam-storage-engine,  Up: storage-engines

13.5 The `InnoDB' Storage Engine
================================

* Menu:

* innodb-overview::              `InnoDB' Overview
* innodb-contact-information::   `InnoDB' Contact Information
* innodb-configuration::         `InnoDB' Configuration
* innodb-parameters::            `InnoDB' Startup Options and System Variables
* innodb-init::                  Creating the `InnoDB' Tablespace
* using-innodb-tables::          Creating and Using `InnoDB' Tables
* adding-and-removing::          Adding and Removing `InnoDB' Data and Log Files
* innodb-backup::                Backing Up and Recovering an `InnoDB' Database
* moving::                       Moving an `InnoDB' Database to Another Machine
* innodb-transaction-model::     `InnoDB' Transaction Model and Locking
* innodb-tuning::                `InnoDB' Performance Tuning Tips
* innodb-multi-versioning::      Implementation of Multi-Versioning
* innodb-table-and-index::       `InnoDB' Table and Index Structures
* file-space-management::        `InnoDB' File Space Management and Disk I/O
* innodb-error-handling::        `InnoDB' Error Handling
* innodb-restrictions::          Restrictions on `InnoDB' Tables
* innodb-troubleshooting::       `InnoDB' Troubleshooting


File: manual.info,  Node: innodb-overview,  Next: innodb-contact-information,  Prev: innodb,  Up: innodb

13.5.1 `InnoDB' Overview
------------------------

`InnoDB' provides MySQL with a transaction-safe (`ACID' compliant)
storage engine that has commit, rollback, and crash recovery
capabilities.  `InnoDB' does locking on the row level and also provides
an Oracle-style consistent non-locking read in `SELECT' statements.
These features increase multi-user concurrency and performance. There
is no need for lock escalation in `InnoDB' because row-level locks fit
in very little space. `InnoDB' also supports `FOREIGN KEY' constraints.
You can freely mix `InnoDB' tables with tables from other MySQL storage
engines, even within the same statement.

`InnoDB' has been designed for maximum performance when processing
large data volumes. Its CPU efficiency is probably not matched by any
other disk-based relational database engine.

Fully integrated with MySQL Server, the `InnoDB' storage engine
maintains its own buffer pool for caching data and indexes in main
memory. `InnoDB' stores its tables and indexes in a tablespace, which
may consist of several files (or raw disk partitions). This is
different from, for example, `MyISAM' tables where each table is stored
using separate files. `InnoDB' tables can be of any size even on
operating systems where file size is limited to 2GB.

`InnoDB' is included in binary distributions by default. The Windows
Essentials installer makes `InnoDB' the MySQL default storage engine on
Windows.

`InnoDB' is used in production at numerous large database sites
requiring high performance. The famous Internet news site Slashdot.org
runs on `InnoDB'. Mytrix, Inc. stores over 1TB of data in `InnoDB', and
another site handles an average load of 800 inserts/updates per second
in `InnoDB'.

`InnoDB' is published under the same GNU GPL License Version 2 (of June
1991) as MySQL. For more information on MySQL licensing, see
`http://www.mysql.com/company/legal/licensing/'.

*Additional resources*

   * A forum dedicated to the `InnoDB' storage engine is available at
     `http://forums.mysql.com/list.php?22'.

   * Innobase Oy also hosts several forums, available at
     `http://forums.innodb.com'.

   * At the 2008 MySQL User Conference, Innobase announced availability
     of an `InnoDB' Plugin for MySQL.  This plugin for MySQL exploits
     the `pluggable storage engine' architecture of MySQL, to permit
     users to replace the `built-in' version of InnoDB in MySQL 5.1
     with a new release of `InnoDB' that offers new features, improved
     performance, enhanced reliability and new capabilities for
     flexibility and ease of use.

     For an overview of plugin features, see
     `http://www.innodb.com/innodb_plugin/features/'.  For the Innobase
     announcement and documentation for the plugin, see
     `http://www.innodb.com/wp/2008/04/15/innodb-plugin-announced/'.


File: manual.info,  Node: innodb-contact-information,  Next: innodb-configuration,  Prev: innodb-overview,  Up: innodb

13.5.2 `InnoDB' Contact Information
-----------------------------------

Contact information for Innobase Oy, producer of the `InnoDB' engine:

Web site: `http://www.innodb.com/'

Email: `innodb_sales_ww at oracle.com' or use this contact form:
`http://www.innodb.com/contact-form'

Phone:

     +358-9-6969 3250 (office, Heikki Tuuri)
     +358-40-5617367 (mobile, Heikki Tuuri)
     +358-40-5939732 (mobile, Satu Sire'n)

Address:

     Innobase Oy Inc.
     World Trade Center Helsinki
     Aleksanterinkatu 17
     P.O.Box 800
     00101 Helsinki
     Finland


File: manual.info,  Node: innodb-configuration,  Next: innodb-parameters,  Prev: innodb-contact-information,  Up: innodb

13.5.3 `InnoDB' Configuration
-----------------------------

* Menu:

* multiple-tablespaces::         Using Per-Table Tablespaces
* innodb-raw-devices::           Using Raw Devices for the Shared Tablespace

The `InnoDB' storage engine is enabled by default. If you don't want to
use `InnoDB' tables, you can add the `skip-innodb' option to your MySQL
option file.

*Note*:

`InnoDB' provides MySQL with a transaction-safe (`ACID' compliant)
storage engine that has commit, rollback, and crash recovery
capabilities.  *However, it cannot do so* if the underlying operating
system or hardware does not work as advertised. Many operating systems
or disk subsystems may delay or reorder write operations to improve
performance. On some operating systems, the very system call that
should wait until all unwritten data for a file has been flushed --
`fsync()' -- might actually return before the data has been flushed to
stable storage. Because of this, an operating system crash or a power
outage may destroy recently committed data, or in the worst case, even
corrupt the database because of write operations having been reordered.
If data integrity is important to you, you should perform some
`pull-the-plug' tests before using anything in production. On Mac OS X
10.3 and up, `InnoDB' uses a special `fcntl()' file flush method.
Under Linux, it is advisable to *disable the write-back cache*.

On ATAPI hard disks, a command such `hdparm -W0 /dev/hda' may work to
disable the write-back cache.  *Beware that some drives or disk
controllers may be unable to disable the write-back cache.*

Two important disk-based resources managed by the `InnoDB' storage
engine are its tablespace data files and its log files.

*Note*:

If you specify no `InnoDB' configuration options, MySQL creates an
auto-extending 10MB data file named `ibdata1' and two 5MB log files
named `ib_logfile0' and `ib_logfile1' in the MySQL data directory. To
get good performance, you should explicitly provide `InnoDB' parameters
as discussed in the following examples. Naturally, you should edit the
settings to suit your hardware and requirements.

*Note*:

It is not a good idea to configure `InnoDB' to use datafiles or
logfiles on NFS volumes. Otherwise, the files might be locked by other
processes and become unavailable for use by MySQL.

MySQL Enterprise

For advice on settings suitable to your specific circumstances,
subscribe to the MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

The examples shown here are representative. See *Note
innodb-parameters:: for additional information about `InnoDB'-related
configuration parameters.

To set up the `InnoDB' tablespace files, use the
`innodb_data_file_path' option in the `[mysqld]' section of the
`my.cnf' option file. On Windows, you can use `my.ini' instead. The
value of `innodb_data_file_path' should be a list of one or more data
file specifications. If you name more than one data file, separate them
by semicolon (``;'') characters:

     innodb_data_file_path=DATAFILE_SPEC1[;DATAFILE_SPEC2]...

For example, a setting that explicitly creates a tablespace having the
same characteristics as the default is as follows:

     [mysqld]
     innodb_data_file_path=ibdata1:10M:autoextend

This setting configures a single 10MB data file named `ibdata1' that is
auto-extending. No location for the file is given, so by default,
`InnoDB' creates it in the MySQL data directory.

Sizes are specified using `M' or `G' suffix letters to indicate units
of MB or GB.

A tablespace containing a fixed-size 50MB data file named `ibdata1' and
a 50MB auto-extending file named `ibdata2' in the data directory can be
configured like this:

     [mysqld]
     innodb_data_file_path=ibdata1:50M;ibdata2:50M:autoextend

The full syntax for a data file specification includes the filename,
its size, and several optional attributes:

     FILE_NAME:FILE_SIZE[:autoextend[:max:MAX_FILE_SIZE]]

The `autoextend' attribute and those following can be used only for the
last data file in the `innodb_data_file_path' line.

If you specify the `autoextend' option for the last data file, `InnoDB'
extends the data file if it runs out of free space in the tablespace.
The increment is 8MB at a time by default. It can be modified by
changing the `innodb_autoextend_increment' system variable.

If the disk becomes full, you might want to add another data file on
another disk. Instructions for reconfiguring an existing tablespace are
given in *Note adding-and-removing::.

`InnoDB' is not aware of the filesystem maximum file size, so be
cautious on filesystems where the maximum file size is a small value
such as 2GB. To specify a maximum size for an auto-extending data file,
use the `max' attribute. The following configuration allows `ibdata1'
to grow up to a limit of 500MB:

     [mysqld]
     innodb_data_file_path=ibdata1:10M:autoextend:max:500M

`InnoDB' creates tablespace files in the MySQL data directory by
default. To specify a location explicitly, use the
`innodb_data_home_dir' option. For example, to use two files named
`ibdata1' and `ibdata2' but create them in the `/ibdata' directory,
configure `InnoDB' like this:

     [mysqld]
     innodb_data_home_dir = /ibdata
     innodb_data_file_path=ibdata1:50M;ibdata2:50M:autoextend

*Note*:

`InnoDB' does not create directories, so make sure that the `/ibdata'
directory exists before you start the server. This is also true of any
log file directories that you configure. Use the Unix or DOS `mkdir'
command to create any necessary directories.

`InnoDB' forms the directory path for each data file by textually
concatenating the value of `innodb_data_home_dir' to the data file name,
adding a pathname separator (slash or backslash) between values if
necessary. If the `innodb_data_home_dir' option is not mentioned in
`my.cnf' at all, the default value is the `dot' directory `./', which
means the MySQL data directory.  (The MySQL server changes its current
working directory to its data directory when it begins executing.)

If you specify `innodb_data_home_dir' as an empty string, you can
specify absolute paths for the data files listed in the
`innodb_data_file_path' value. The following example is equivalent to
the preceding one:

     [mysqld]
     innodb_data_home_dir =
     innodb_data_file_path=/ibdata/ibdata1:50M;/ibdata/ibdata2:50M:autoextend

*A simple `my.cnf' example.* Suppose that you have a computer with 128MB
RAM and one hard disk. The following example shows possible
configuration parameters in `my.cnf' or `my.ini' for `InnoDB',
including the `autoextend' attribute. The example suits most users,
both on Unix and Windows, who do not want to distribute `InnoDB' data
files and log files onto several disks. It creates an auto-extending
data file `ibdata1' and two `InnoDB' log files `ib_logfile0' and
`ib_logfile1' in the MySQL data directory.

     [mysqld]
     # You can write your other MySQL server options here
     # ...
     # Data files must be able to hold your data and indexes.
     # Make sure that you have enough free disk space.
     innodb_data_file_path = ibdata1:10M:autoextend
     #
     # Set buffer pool size to 50-80% of your computer's memory
     innodb_buffer_pool_size=70M
     innodb_additional_mem_pool_size=10M
     #
     # Set the log file size to about 25% of the buffer pool size
     innodb_log_file_size=20M
     innodb_log_buffer_size=8M
     #
     innodb_flush_log_at_trx_commit=1

Make sure that the MySQL server has the proper access rights to create
files in the data directory. More generally, the server must have
access rights in any directory where it needs to create data files or
log files.

Note that data files must be less than 2GB in some filesystems.  The
combined size of the log files must be less than 4GB. The combined size
of data files must be at least 10MB.

When you create an `InnoDB' tablespace for the first time, it is best
that you start the MySQL server from the command prompt. `InnoDB' then
prints the information about the database creation to the screen, so
you can see what is happening. For example, on Windows, if `mysqld' is
located in `C:\Program Files\MySQL\MySQL Server 5.1\bin', you can start
it like this:

     C:\> "C:\Program Files\MySQL\MySQL Server 5.1\bin\mysqld" --console

If you do not send server output to the screen, check the server's
error log to see what `InnoDB' prints during the startup process.

See *Note innodb-init::, for an example of what the information
displayed by `InnoDB' should look like.

You can place `InnoDB' options in the `[mysqld]' group of any option
file that your server reads when it starts. The locations for option
files are described in *Note option-files::.

If you installed MySQL on Windows using the installation and
configuration wizards, the option file will be the `my.ini' file
located in your MySQL installation directory. See *Note
mysql-config-wizard-file-location::.

If your PC uses a boot loader where the `C:' drive is not the boot
drive, your only option is to use the `my.ini' file in your Windows
directory (typically `C:\WINDOWS'). You can use the `SET' command at
the command prompt in a console window to print the value of `WINDIR':

     C:\> SET WINDIR
     windir=C:\WINDOWS

If you want to make sure that `mysqld' reads options only from a
specific file, you can use the `--defaults-file' option as the first
option on the command line when starting the server:

     mysqld --defaults-file=YOUR_PATH_TO_MY_CNF

*An advanced `my.cnf' example.* Suppose that you have a Linux computer
with 2GB RAM and three 60GB hard disks at directory paths `/', `/dr2'
and `/dr3'. The following example shows possible configuration
parameters in `my.cnf' for `InnoDB'.

     [mysqld]
     # You can write your other MySQL server options here
     # ...
     innodb_data_home_dir =
     #
     # Data files must be able to hold your data and indexes
     innodb_data_file_path = /db/ibdata1:2000M;/dr2/db/ibdata2:2000M:autoextend
     #
     # Set buffer pool size to 50-80% of your computer's memory,
     # but make sure on Linux x86 total memory usage is < 2GB
     innodb_buffer_pool_size=1G
     innodb_additional_mem_pool_size=20M
     innodb_log_group_home_dir = /dr3/iblogs
     #
     innodb_log_files_in_group = 2
     #
     # Set the log file size to about 25% of the buffer pool size
     innodb_log_file_size=250M
     innodb_log_buffer_size=8M
     #
     innodb_flush_log_at_trx_commit=1
     innodb_lock_wait_timeout=50
     #
     # Uncomment the next lines if you want to use them
     #innodb_thread_concurrency=5

In some cases, database performance improves if all the data is not
placed on the same physical disk. Putting log files on a different disk
from data is very often beneficial for performance.  The example
illustrates how to do this. It places the two data files on different
disks and places the log files on the third disk. `InnoDB' fills the
tablespace beginning with the first data file. You can also use raw
disk partitions (raw devices) as `InnoDB' data files, which may speed
up I/O. See *Note innodb-raw-devices::.

*Warning*:

On 32-bit GNU/Linux x86, you must be careful not to set memory usage
too high. `glibc' may allow the process heap to grow over thread
stacks, which crashes your server. It is a risk if the value of the
following expression is close to or exceeds 2GB:

     innodb_buffer_pool_size
     + key_buffer_size
     + max_connections*(sort_buffer_size+read_buffer_size+binlog_cache_size)
     + max_connections*2MB

Each thread uses a stack (often 2MB, but only 256KB in MySQL AB
binaries) and in the worst case also uses `sort_buffer_size +
read_buffer_size' additional memory.

*How to tune other `mysqld' server parameters?* The following values
are typical and suit most users:

     [mysqld]
     skip-external-locking
     max_connections=200
     read_buffer_size=1M
     sort_buffer_size=1M
     #
     # Set key_buffer to 5 - 50% of your RAM depending on how much
     # you use MyISAM tables, but keep key_buffer_size + InnoDB
     # buffer pool size < 80% of your RAM
     key_buffer_size=VALUE


File: manual.info,  Node: multiple-tablespaces,  Next: innodb-raw-devices,  Prev: innodb-configuration,  Up: innodb-configuration

13.5.3.1 Using Per-Table Tablespaces
....................................

You can store each `InnoDB' table and its indexes in its own file. This
feature is called `multiple tablespaces' because in effect each table
has its own tablespace.

Using multiple tablespaces can be beneficial to users who want to move
specific tables to separate physical disks or who wish to restore
backups of single tables quickly without interrupting the use of the
remaining `InnoDB' tables.

You can enable multiple tablespaces by adding this line to the
`[mysqld]' section of `my.cnf':

     [mysqld]
     innodb_file_per_table

After restarting the server, `InnoDB' stores each newly created table
into its own file `TBL_NAME.ibd' in the database directory where the
table belongs. This is similar to what the `MyISAM' storage engine
does, but `MyISAM' divides the table into a data file `TBL_NAME.MYD' and
the index file `TBL_NAME.MYI'.  For `InnoDB', the data and the indexes
are stored together in the `.ibd' file. The `TBL_NAME.frm' file is
still created as usual.

If you remove the `innodb_file_per_table' line from `my.cnf' and
restart the server, `InnoDB' creates tables inside the shared
tablespace files again.

`innodb_file_per_table' affects only table creation, not access to
existing tables. If you start the server with this option, new tables
are created using `.ibd' files, but you can still access tables that
exist in the shared tablespace. If you remove the option and restart
the server, new tables are created in the shared tablespace, but you
can still access any tables that were created using multiple
tablespaces.

*Note*:

`InnoDB' always needs the shared tablespace because it puts its
internal data dictionary and undo logs there. The `.ibd' files are not
sufficient for `InnoDB' to operate.

*Note*:

You cannot freely move `.ibd' files between database directories as you
can with `MyISAM' table files. This is because the table definition
that is stored in the `InnoDB' shared tablespace includes the database
name, and because `InnoDB' must preserve the consistency of transaction
IDs and log sequence numbers.

To move an `.ibd' file and the associated table from one database to
another, use a `RENAME TABLE' statement:

     RENAME TABLE DB1.TBL_NAME TO DB2.TBL_NAME;

If you have a `clean' backup of an `.ibd' file, you can restore it to
the MySQL installation from which it originated as follows:

  1. Issue this `ALTER TABLE' statement:

          ALTER TABLE TBL_NAME DISCARD TABLESPACE;

     *Caution*:

     This statement deletes the current `.ibd' file.

  2. Put the backup `.ibd' file back in the proper database directory.

  3. Issue this `ALTER TABLE' statement:

          ALTER TABLE TBL_NAME IMPORT TABLESPACE;

In this context, a `clean' `.ibd' file backup means:

   * There are no uncommitted modifications by transactions in the
     `.ibd' file.

   * There are no unmerged insert buffer entries in the `.ibd' file.

   * Purge has removed all delete-marked index records from the `.ibd'
     file.

   * `mysqld' has flushed all modified pages of the `.ibd' file from
     the buffer pool to the file.

You can make a clean backup `.ibd' file using the following method:

  1. Stop all activity from the `mysqld' server and commit all
     transactions.

  2. Wait until `SHOW ENGINE INNODB STATUS' shows that there are no
     active transactions in the database, and the main thread status of
     `InnoDB' is `Waiting for server activity'. Then you can make a
     copy of the `.ibd' file.

Another method for making a clean copy of an `.ibd' file is to use the
commercial `InnoDB Hot Backup' tool:

  1. Use `InnoDB Hot Backup' to back up the `InnoDB' installation.

  2. Start a second `mysqld' server on the backup and let it clean up
     the `.ibd' files in the backup.


File: manual.info,  Node: innodb-raw-devices,  Prev: multiple-tablespaces,  Up: innodb-configuration

13.5.3.2 Using Raw Devices for the Shared Tablespace
....................................................

You can use raw disk partitions as data files in the shared tablespace.
By using a raw disk, you can perform non-buffered I/O on Windows and on
some Unix systems without filesystem overhead, which may improve
performance.

When you create a new data file, you must put the keyword `newraw'
immediately after the data file size in `innodb_data_file_path'. The
partition must be at least as large as the size that you specify. Note
that 1MB in `InnoDB' is 1024 x 1024 bytes, whereas 1MB in disk
specifications usually means 1,000,000 bytes.

     [mysqld]
     innodb_data_home_dir=
     innodb_data_file_path=/dev/hdd1:3Gnewraw;/dev/hdd2:2Gnewraw

The next time you start the server, `InnoDB' notices the `newraw'
keyword and initializes the new partition. However, do not create or
change any `InnoDB' tables yet. Otherwise, when you next restart the
server, `InnoDB' reinitializes the partition and your changes are lost.
(As a safety measure `InnoDB' prevents users from modifying data when
any partition with `newraw' is specified.)

After `InnoDB' has initialized the new partition, stop the server,
change `newraw' in the data file specification to `raw':

     [mysqld]
     innodb_data_home_dir=
     innodb_data_file_path=/dev/hdd1:5Graw;/dev/hdd2:2Graw

Then restart the server and `InnoDB' allows changes to be made.

On Windows, you can allocate a disk partition as a data file like this:

     [mysqld]
     innodb_data_home_dir=
     innodb_data_file_path=//./D::10Gnewraw

The `//./' corresponds to the Windows syntax of `\\.\' for accessing
physical drives.

When you use raw disk partitions, be sure that they have permissions
that allow read and write access by the account used for running the
MySQL server.


File: manual.info,  Node: innodb-parameters,  Next: innodb-init,  Prev: innodb-configuration,  Up: innodb

13.5.4 `InnoDB' Startup Options and System Variables
----------------------------------------------------

This section describes the `InnoDB'-related command options and system
variables. System variables that are true or false can be enabled at
server startup by naming them, or disabled by using a `skip-' prefix.
For example, to enable or disable `InnoDB' checksums, you can use
`--innodb_checksums' or `--skip-innodb_checksums' on the command line,
or `innodb_checksums' or `skip-innodb_checksums' in an option file.
System variables that take a numeric value can be specified as
`--VAR_NAME=VALUE' on the command line or as `VAR_NAME=VALUE' in option
files. For more information on specifying options and system variables,
see *Note program-options::. Many of the system variables can be
changed at runtime (see *Note using-system-variables::).

MySQL Enterprise

The MySQL Enterprise Monitor provides expert advice on InnoDB start-up
options and related system variables. For more information see
`http://www.mysql.com/products/enterprise/advisors.html'.

*Name*                        *Cmd-Line*                                                 *Option file*                                              *System Var*                                               *Status Var*                                               *Var Scope*                                                *Dynamic*
Com_show_innodb_status                                                                                                                                                                                         Yes                                                        Both                                                       No
Com_show_ndb_status                                                                                                                                                                                            Yes                                                        Both                                                       No
foreign_key_checks                                                                                                                                  Yes                                                                                                                   Session                                                    Yes
have_innodb                                                                                                                                         Yes                                                                                                                   Global                                                     No
innodb                        Yes                                                        Yes                                                                                                                                                                                                                                         
innodb_adaptive_hash_index    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_additional_mem_pool_sizeYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_autoextend_increment   Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_autoinc_lock_mode      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_buffer_pool_awe_mem_mb Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_buffer_pool_pages_data                                                                                                                                                                                  Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_dirty                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_flushed                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_free                                                                                                                                                                                  Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_latched                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_misc                                                                                                                                                                                  Yes                                                        Global                                                     No
Innodb_buffer_pool_pages_total                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_read_ahead_rnd                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_read_ahead_seq                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_read_requests                                                                                                                                                                                 Yes                                                        Global                                                     No
Innodb_buffer_pool_reads                                                                                                                                                                                       Yes                                                        Global                                                     No
innodb_buffer_pool_size       Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_buffer_pool_wait_free                                                                                                                                                                                   Yes                                                        Global                                                     No
Innodb_buffer_pool_write_requests                                                                                                                                                                                 Yes                                                        Global                                                     No
innodb_checksums              Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_commit_concurrency     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_concurrency_tickets    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_data_file_path         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_data_fsyncs                                                                                                                                                                                             Yes                                                        Global                                                     No
innodb_data_home_dir          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_data_pending_fsyncs                                                                                                                                                                                     Yes                                                        Global                                                     No
Innodb_data_pending_reads                                                                                                                                                                                      Yes                                                        Global                                                     No
Innodb_data_pending_writes                                                                                                                                                                                     Yes                                                        Global                                                     No
Innodb_data_read                                                                                                                                                                                               Yes                                                        Global                                                     No
Innodb_data_reads                                                                                                                                                                                              Yes                                                        Global                                                     No
Innodb_data_writes                                                                                                                                                                                             Yes                                                        Global                                                     No
Innodb_data_written                                                                                                                                                                                            Yes                                                        Global                                                     No
Innodb_dblwr_pages_written                                                                                                                                                                                     Yes                                                        Global                                                     No
Innodb_dblwr_writes                                                                                                                                                                                            Yes                                                        Global                                                     No
innodb_doublewrite            Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_fast_shutdown          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_file_io_threads        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_file_per_table         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_flush_log_at_trx_commitYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_flush_method           Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_force_recovery         Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_locks_unsafe_for_binlogYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_lock_wait_timeout      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_log_arch_dir           Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_log_archive            Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_log_buffer_size        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_log_files_in_group     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_log_file_size          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_log_group_home_dir     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_log_waits                                                                                                                                                                                               Yes                                                        Global                                                     No
Innodb_log_write_requests                                                                                                                                                                                      Yes                                                        Global                                                     No
Innodb_log_writes                                                                                                                                                                                              Yes                                                        Global                                                     No
innodb_max_dirty_pages_pct    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_max_purge_lag          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_mirrored_log_groups    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_open_files             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_os_log_fsyncs                                                                                                                                                                                           Yes                                                        Global                                                     No
Innodb_os_log_pending_fsyncs                                                                                                                                                                                   Yes                                                        Global                                                     No
Innodb_os_log_pending_writes                                                                                                                                                                                   Yes                                                        Global                                                     No
Innodb_os_log_written                                                                                                                                                                                          Yes                                                        Global                                                     No
Innodb_pages_created                                                                                                                                                                                           Yes                                                        Global                                                     No
Innodb_page_size                                                                                                                                                                                               Yes                                                        Global                                                     No
Innodb_pages_read                                                                                                                                                                                              Yes                                                        Global                                                     No
Innodb_pages_written                                                                                                                                                                                           Yes                                                        Global                                                     No
innodb_rollback_on_timeout    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
Innodb_row_lock_current_waits                                                                                                                                                                                  Yes                                                        Global                                                     No
Innodb_row_lock_time                                                                                                                                                                                           Yes                                                        Global                                                     No
Innodb_row_lock_time_avg                                                                                                                                                                                       Yes                                                        Global                                                     No
Innodb_row_lock_time_max                                                                                                                                                                                       Yes                                                        Global                                                     No
Innodb_row_lock_waits                                                                                                                                                                                          Yes                                                        Global                                                     No
Innodb_rows_deleted                                                                                                                                                                                            Yes                                                        Global                                                     No
Innodb_rows_inserted                                                                                                                                                                                           Yes                                                        Global                                                     No
Innodb_rows_read                                                                                                                                                                                               Yes                                                        Global                                                     No
Innodb_rows_updated                                                                                                                                                                                            Yes                                                        Global                                                     No
innodb_stats_on_metadata      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_status_file            Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
innodb_support_xa             Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
innodb_sync_spin_loops        Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_table_locks            Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
innodb_thread_concurrency     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
innodb_thread_sleep_delay     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
plugin-innodb                 Yes                                                        Yes                                                                                                                                                                                                                                         
plugin_innodb_additional_mem_pool_sizeYes                                                        Yes                                                        Yes                                                                                                                   Both                                                       No
plugin_innodb_autoextend_incrementYes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
plugin_innodb_buffer_pool_awe_mem_mbYes                                                        Yes                                                                                                                                                                              Both                                                       No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Both                                                       No
innodb_buffer_pool_awe_mem_mb                                                                                                                                                                                                                                                                                                        
plugin_innodb_buffer_pool_sizeYes                                                        Yes                                                        Yes                                                                                                                   Both                                                       No
plugin_innodb_checksums       Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
plugin_innodb_commit_concurrencyYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
plugin_innodb_concurrency_ticketsYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
plugin_innodb_data_file_path  Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_data_home_dir   Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin-innodb-doublewrite     Yes                                                        Yes                                                                                                                                                                              Global                                                     No
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     No
plugin_innodb_doublewrite                                                                                                                                                                                                                                                                                                            
plugin_innodb_fast_shutdown   Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_file_io_threads Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_file_per_table  Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_flush_log_at_trx_commitYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
plugin_innodb_flush_method    Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_force_recovery  Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_locks_unsafe_for_binlogYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_lock_wait_timeoutYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_log_archive     Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_log_buffer_size Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_log_files_in_groupYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_log_file_size   Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_log_group_home_dirYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_max_dirty_pages_pctYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
plugin_innodb_max_purge_lag   Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
plugin_innodb_mirrored_log_groupsYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_open_files      Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     No
plugin_innodb_rollback_on_timeoutYes                                                        Yes                                                        Yes                                                                                                                                                                              No
plugin_innodb_stats_on_metadataYes                                                        Yes                                                        Yes                                                                                                                                                                              No
plugin_innodb_status_file     Yes                                                        Yes                                                        Yes                                                                                                                                                                              No
plugin_innodb_support_xa      Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
plugin_innodb_sync_spin_loops Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
plugin_innodb_table_locks     Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
plugin_innodb_thread_concurrencyYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
plugin_innodb_thread_sleep_delayYes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
skip-innodb                   Yes                                                        Yes                                                                                                                                                                                                                                         
skip-innodb-checksums         Yes                                                        Yes                                                                                                                                                                                                                                         
skip-plugin-innodb            Yes                                                        Yes                                                                                                                                                                                                                                         
skip-plugin-innodb-checksums  Yes                                                        Yes                                                                                                                                                                                                                                         
sync-binlog                   Yes                                                        Yes                                                                                                                                                                              Global                                                     Yes
- _Variable_: sync_binlog                                                                                                                           Yes                                                                                                                   Global                                                     Yes
timed_mutexes                 Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
unique_checks                                                                                                                                       Yes                                                                                                                   Session                                                    Yes

`InnoDB' command options:

   *  `--innodb'

     Enables the `InnoDB' storage engine, if the server was compiled
     with `InnoDB' support.  Use `--skip-innodb' to disable `InnoDB'.

   *  `--innodb_status_file'

     Causes `InnoDB' to create a file named
     `<DATADIR>/innodb_status.<PID>' in the MySQL data directory.
     `InnoDB' periodically writes the output of `SHOW ENGINE INNODB
     STATUS' to this file.

`InnoDB' system variables:

   *  `innodb_adaptive_hash_index'

     Whether InnoDB adaptive hash indexes are enabled or disabled.  By
     default, this variable is enabled. Use
     `--skip-innodb_adaptive_hash_index' at server startup to disable
     it. See *Note innodb-adaptive-hash:: This variable was added in
     MySQL 5.1.24.

   *  `innodb_additional_mem_pool_size'

     The size in bytes of a memory pool `InnoDB' uses to store data
     dictionary information and other internal data structures. The
     more tables you have in your application, the more memory you need
     to allocate here. If `InnoDB' runs out of memory in this pool, it
     starts to allocate memory from the operating system and writes
     warning messages to the MySQL error log. The default value is 1MB.

   *  `innodb_autoextend_increment'

     The increment size (in MB) for extending the size of an
     auto-extending tablespace when it becomes full. The default value
     is 8.

   *  `innodb_buffer_pool_awe_mem_mb'

     The size of the buffer pool (in MB), if it is placed in the AWE
     memory. This is relevant only in 32-bit Windows. If your 32-bit
     Windows operating system supports more than 4GB memory, using
     so-called `Address Windowing Extensions,' you can allocate the
     `InnoDB' buffer pool into the AWE physical memory using this
     variable. The maximum possible value for this variable is 63000.
     If it is greater than 0, `innodb_buffer_pool_size' is the window
     in the 32-bit address space of `mysqld' where `InnoDB' maps that
     AWE memory. A good value for `innodb_buffer_pool_size' is 500MB.

     To take advantage of AWE memory, you will need to recompile MySQL
     yourself. The current project settings needed for doing this can
     be found in the `storage/innobase/os/os0proj.c' source file.

     This variable was removed in MySQL 5.1.13.

   *  `innodb_autoinc_lock_mode'

     The locking mode to use for generating auto-increment values.  The
     allowable values are 0, 1, or 2, for `traditional', `consecutive',
     or `interleaved' lock mode, respectively. The characteristics of
     these modes are described in *Note
     innodb-auto-increment-handling::.

     This variable was added in MySQL 5.1.22 with a default of 1
     (`consecutive' lock mode). Before 5.1.22, `InnoDB' uses
     `traditional' lock mode.

   *  `innodb_buffer_pool_size'

     The size in bytes of the memory buffer `InnoDB' uses to cache data
     and indexes of its tables. The larger you set this value, the less
     disk I/O is needed to access data in tables. On a dedicated
     database server, you may set this to up to 80% of the machine
     physical memory size. However, do not set it too large because
     competition for physical memory might cause paging in the
     operating system.

   *  `innodb_checksums'

     `InnoDB' can use checksum validation on all pages read from the
     disk to ensure extra fault tolerance against broken hardware or
     data files. This validation is enabled by default. However, under
     some rare circumstances (such as when running benchmarks) this
     extra safety feature is unneeded and can be disabled with
     `--skip-innodb-checksums'.

   *  `innodb_commit_concurrency'

     The number of threads that can commit at the same time.  Setting
     this parameter to 0 allows any number of transactions to commit
     simultaneously.

   *  `innodb_concurrency_tickets'

     The number of threads that can enter `InnoDB' concurrently is
     determined by the `innodb_thread_concurrency' variable. A thread
     is placed in a queue when it tries to enter `InnoDB' if the number
     of threads has already reached the concurrency limit. When a
     thread is allowed to enter `InnoDB', it is given a number of `free
     tickets' equal to the value of `innodb_concurrency_tickets', and
     the thread can enter and leave `InnoDB' freely until it has used
     up its tickets. After that point, the thread again becomes subject
     to the concurrency check (and possible queuing) the next time it
     tries to enter `InnoDB'.

   *  `innodb_data_file_path'

     The paths to individual data files and their sizes. The full
     directory path to each data file is formed by concatenating
     `innodb_data_home_dir' to each path specified here. The file sizes
     are specified in MB or GB (1024MB) by appending `M' or `G' to the
     size value. The sum of the sizes of the files must be at least
     10MB. If you do not specify `innodb_data_file_path', the default
     behavior is to create a single 10MB auto-extending data file named
     `ibdata1'. The size limit of individual files is determined by
     your operating system. You can set the file size to more than 4GB
     on those operating systems that support big files. You can also
     use raw disk partitions as data files. See *Note
     innodb-raw-devices::.

   *  `innodb_data_home_dir'

     The common part of the directory path for all `InnoDB' data files.
     If you do not set this value, the default is the MySQL data
     directory. You can specify the value as an empty string, in which
     case you can use absolute file paths in `innodb_data_file_path'.

   *  `innodb_doublewrite'

     By default, `InnoDB' stores all data twice, first to the
     doublewrite buffer, and then to the actual data files. This
     variable is enabled by default. It can be turned off with
     `--skip-innodb_doublewrite' for benchmarks or cases when top
     performance is needed rather than concern for data integrity or
     possible failures.

   *  `innodb_fast_shutdown'

     If you set this variable to 0, `InnoDB' does a full purge and an
     insert buffer merge before a shutdown.  These operations can take
     minutes, or even hours in extreme cases. If you set this variable
     to 1, `InnoDB' skips these operations at shutdown.  The default
     value is 1. If you set it to 2, `InnoDB' will just flush its logs
     and then shut down cold, as if MySQL had crashed; no committed
     transaction will be lost, but crash recovery will be done at the
     next startup. A value of 2 cannot be used on NetWare.

   *  `innodb_file_io_threads'

     The number of file I/O threads in `InnoDB'.  Normally, this should
     be left at the default value of 4, but disk I/O on Windows may
     benefit from a larger number. On Unix, increasing the number has
     no effect; `InnoDB' always uses the default value.

   *  `innodb_file_per_table'

     If this variable is enabled, `InnoDB' creates each new table using
     its own `.ibd' file for storing data and indexes, rather than in
     the shared tablespace. The default is to create tables in the
     shared tablespace. See *Note multiple-tablespaces::.

   *  `innodb_flush_log_at_trx_commit'

     When `innodb_flush_log_at_trx_commit' is set to 0, the log buffer
     is written out to the log file once per second and the flush to
     disk operation is performed on the log file, but nothing is done
     at a transaction commit. When this value is 1 (the default), the
     log buffer is written out to the log file at each transaction
     commit and the flush to disk operation is performed on the log
     file. When set to 2, the log buffer is written out to the file at
     each commit, but the flush to disk operation is not performed on
     it. However, the flushing on the log file takes place once per
     second also when the value is 2. Note that the once-per-second
     flushing is not 100% guaranteed to happen every second, due to
     process scheduling issues.

     The default value of this variable is 1, which is the value that
     is required for ACID compliance. You can achieve better
     performance by setting the value different from 1, but then you
     can lose at most one second worth of transactions in a crash. If
     you set the value to 0, then any `mysqld' process crash can erase
     the last second of transactions. If you set the value to 2, then
     only an operating system crash or a power outage can erase the last
     second of transactions. However, `InnoDB''s crash recovery is not
     affected and thus crash recovery does work regardless of the
     value. Note that many operating systems and some disk hardware
     fool the flush-to-disk operation. They may tell `mysqld' that the
     flush has taken place, even though it has not. Then the durability
     of transactions is not guaranteed even with the setting 1, and in
     the worst case a power outage can even corrupt the `InnoDB'
     database. Using a battery-backed disk cache in the SCSI disk
     controller or in the disk itself speeds up file flushes, and makes
     the operation safer. You can also try using the Unix command
     `hdparm' to disable the caching of disk writes in hardware caches,
     or use some other command specific to the hardware vendor.

     Note: For the greatest possible durability and consistency in a
     replication setup using `InnoDB' with transactions, you should use
     `innodb_flush_log_at_trx_commit=1' and `sync_binlog=1' in your
     master server `my.cnf' file.

   *  `innodb_flush_method'

     By default, `InnoDB' uses `fsync()' to flush both the data and log
     files. If `innodb_flush_method' option is set to `O_DSYNC',
     `InnoDB' uses `O_SYNC' to open and flush the log files, but uses
     `fsync()' to flush the data files. If `O_DIRECT' is specified
     (available on some GNU/Linux versions, FreeBSD and Solaris),
     `InnoDB' uses `O_DIRECT' (or `directio()' on Solaris) to open the
     data files, and uses `fsync()' to flush both the data and log
     files. Note that `InnoDB' uses `fsync()' instead of `fdatasync()',
     and it does not use `O_DSYNC' by default because there have been
     problems with it on many varieties of Unix. This variable is
     relevant only for Unix. On Windows, the flush method is always
     `async_unbuffered' and cannot be changed.

     Different values of this variable can have a marked effect on
     `InnoDB performance'. For example, on some systems where `InnoDB'
     data and log files are located on a SAN, it has been found that
     setting `innodb_flush_method' to `O_DIRECT' can degrade
     performance of simple `SELECT' statements by a factor of three.

     Formerly it was possible to specify a value of `fdatasync' to
     obtain the default behavior.  This is no longer possible as of
     MySQL 5.1.24 because it can be confusing that a value of
     `fdatasync' causes use of `fsync()' rather than `fdatasync()' for
     flushing.

   *  `innodb_force_recovery'

     The crash recovery mode.

     *Warning*:

     This variable should be set greater than 0 only in an emergency
     situation when you want to dump your tables from a corrupt
     database! Possible values are from 1 to 6. The meanings of these
     values are described in *Note forcing-recovery::. As a safety
     measure, `InnoDB' prevents any changes to its data when this
     variable is greater than 0.

   *  `innodb_lock_wait_timeout'

     The timeout in seconds an `InnoDB' transaction may wait for a row
     lock before giving up. The default is 50 seconds. When trying to
     access a row that is locked by another `InnoDB' transaction a
     connection will hang for at most this many seconds before issuing
     the following error:

          ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction

     In this case, the current statement is not executed. The current
     transaction is _not_ rolled back.  (To have the entire transaction
     roll back, start the server with the
     `--innodb_rollback_on_timeout' option, available as of MySQL
     5.1.15. See also *Note innodb-error-handling::.)

     `innodb_lock_wait_timeout' applies to `InnoDB' row locks only. A
     MySQL table lock does not happen inside `InnoDB' and this timeout
     does not apply to waits for table locks.

     `InnoDB' does detect transaction deadlocks in its own lock table
     immediately and rolls back one transaction.  This timeout does not
     apply to such a wait.

   *  `innodb_locks_unsafe_for_binlog'

     This variable controls next-key locking in `InnoDB' searches and
     index scans. By default, this variable is 0 (disabled), which
     means that next-key locking is enabled.

     Normally, `InnoDB' uses an algorithm called _next-key locking_.
     `InnoDB' performs row-level locking in such a way that when it
     searches or scans a table index, it sets shared or exclusive locks
     on any index records it encounters.  Thus, the row-level locks are
     actually index record locks.

     The locks that `InnoDB' sets on index records also affect the
     `gap' preceding that index record. If a user has a shared or
     exclusive lock on record `R' in an index, another user cannot
     insert a new index record immediately before `R' in the order of
     the index.

     Enabling `innodb_locks_unsafe_for_binlog' causes `InnoDB' not to
     use next-key locking in searches or index scans. Next-key locking
     is still used to ensure foreign key constraints and duplicate key
     checking.  Note that enabling this variable may cause phantom
     problems: Suppose that there is an index on the `id' column and
     that you want to read and lock all children from the `child' table
     with an identifier value larger than 100, with the intention of
     updating some column in the selected rows later:

          SELECT * FROM child WHERE id > 100 FOR UPDATE;

     The query scans the index starting from the first record where
     `id' is greater than 100. If the locks set on the index records do
     not lock out inserts made in the gaps, another client can insert a
     new row into the table. If you execute the same `SELECT' within
     the same transaction, you see a new row in the result set returned
     by the query. This also means that if new items are added to the
     database, `InnoDB' does not guarantee serializability. Therefore,
     if this variable is enabled, `InnoDB' guarantees at most isolation
     level `READ COMMITTED'. (Conflict serializability is still
     guaranteed.)

     Enabling this variable has an additional effect: `InnoDB' in an
     `UPDATE' or a `DELETE' only locks rows that it updates or deletes.
     This greatly reduces the probability of deadlocks, but they can
     happen. Note that enabling this variable still does not allow
     operations such as `UPDATE' to overtake other similar operations
     (such as another `UPDATE') even in the case when they affect
     different rows. Consider the following example, beginning with
     this table:

          CREATE TABLE A(A INT NOT NULL, B INT) ENGINE = InnoDB;
          INSERT INTO A VALUES (1,2),(2,3),(3,2),(4,3),(5,2);
          COMMIT;

     Suppose that one client executes these statements:

          SET AUTOCOMMIT = 0;
          UPDATE A SET B = 5 WHERE B = 3;

     Then suppose that another client executes these statements
     following those of the first client:

          SET AUTOCOMMIT = 0;
          UPDATE A SET B = 4 WHERE B = 2;

     In this case, the second `UPDATE' must wait for a commit or
     rollback of the first `UPDATE'. The first `UPDATE' has an
     exclusive lock on row (2,3), and the second `UPDATE' while
     scanning rows also tries to acquire an exclusive lock for the same
     row, which it cannot have. This is because `UPDATE' two first
     acquires an exclusive lock on a row and then determines whether
     the row belongs to the result set. If not, it releases the
     unnecessary lock, when the `innodb_locks_unsafe_for_binlog'
     variable is enabled.

     Therefore, `InnoDB' executes `UPDATE' one as follows:

          x-lock(1,2)
          unlock(1,2)
          x-lock(2,3)
          update(2,3) to (2,5)
          x-lock(3,2)
          unlock(3,2)
          x-lock(4,3)
          update(4,3) to (4,5)
          x-lock(5,2)
          unlock(5,2)

     `InnoDB' executes `UPDATE' two as follows:

          x-lock(1,2)
          update(1,2) to (1,4)
          x-lock(2,3) - wait for query one to commit or rollback

   *  `innodb_log_arch_dir'

     This variable is deprecated, and was removed in MySQL 5.1.21.

   *  `innodb_log_archive'

     This variable is deprecated, and was removed in MySQL 5.1.18.

   *  `innodb_log_buffer_size'

     The size in bytes of the buffer that `InnoDB' uses to write to the
     log files on disk. Sensible values range from 1MB to 8MB. The
     default is 1MB. A large log buffer allows large transactions to
     run without a need to write the log to disk before the
     transactions commit. Thus, if you have big transactions, making
     the log buffer larger saves disk I/O.

   *  `innodb_log_file_size'

     The size in bytes of each log file in a log group. The combined
     size of log files must be less than 4GB on 32-bit computers. The
     default is 5MB. Sensible values range from 1MB to 1/N-th of the
     size of the buffer pool, where N is the number of log files in the
     group. The larger the value, the less checkpoint flush activity is
     needed in the buffer pool, saving disk I/O.  But larger log files
     also mean that recovery is slower in case of a crash.

   *  `innodb_log_files_in_group'

     The number of log files in the log group.  `InnoDB' writes to the
     files in a circular fashion. The default (and recommended) is 2.

   *  `innodb_log_group_home_dir'

     The directory path to the `InnoDB' log files.  If you do not
     specify any `InnoDB' log variables, the default is to create two
     5MB files names `ib_logfile0' and `ib_logfile1' in the MySQL data
     directory.

   *  `innodb_max_dirty_pages_pct'

     This is an integer in the range from 0 to 100. The default is 90.
     The main thread in `InnoDB' tries to write pages from the buffer
     pool so that the percentage of dirty (not yet written) pages will
     not exceed this value.

   *  `innodb_max_purge_lag'

     This variable controls how to delay `INSERT', `UPDATE' and `DELETE'
     operations when the purge operations are lagging (see *Note
     innodb-multi-versioning::). The default value of this variable is
     0, meaning that there are no delays.

     The `InnoDB' transaction system maintains a list of transactions
     that have delete-marked index records by `UPDATE' or `DELETE'
     operations. Let the length of this list be PURGE_LAG. When
     PURGE_LAG exceeds `innodb_max_purge_lag', each `INSERT', `UPDATE'
     and `DELETE' operation is delayed by
     ((PURGE_LAG/`innodb_max_purge_lag')x10)-5 milliseconds. The delay
     is computed in the beginning of a purge batch, every ten seconds.
     The operations are not delayed if purge cannot run because of an
     old consistent read view that could see the rows to be purged.

     A typical setting for a problematic workload might be 1 million,
     assuming that our transactions are small, only 100 bytes in size,
     and we can allow 100MB of unpurged rows in our tables.

   *  `innodb_mirrored_log_groups'

     The number of identical copies of log groups to keep for the
     database. Currently, this should be set to 1.

   *  `innodb_open_files'

     This variable is relevant only if you use multiple tablespaces in
     `InnoDB'. It specifies the maximum number of `.ibd' files that
     `InnoDB' can keep open at one time. The minimum value is 10. The
     default is 300.

     The file descriptors used for `.ibd' files are for `InnoDB' only.
     They are independent of those specified by the `--open-files-limit'
     server option, and do not affect the operation of the table cache.

   *  `innodb_rollback_on_timeout'

     In MySQL 5.1, `InnoDB' rolls back only the last statement on a
     transaction timeout. If this option is given, a transaction
     timeout causes `InnoDB' to abort and roll back the entire
     transaction (the same behavior as in MySQL 4.1). This variable was
     added in MySQL 5.1.15.

   *  `innodb_stats_on_metadata'

     When this variable is enabled (which is the default, as before the
     variable was created), `InnoDB' updates statistics during metadata
     statements such as `SHOW TABLE STATUS' or `SHOW INDEX', or when
     accessing the `INFORMATION_SCHEMA' tables `TABLES' or
     `STATISTICS'. (These updates are similar to what happens for
     `ANALYZE TABLE'.) When disabled, `InnoDB' does not updates
     statistics during these operations. Disabling this variable can
     improve access speed for schemas that have a large number of
     tables or indexes. It can also improve the stability of execution
     plans for queries that involve `InnoDB' tables.

     This variable was added in MySQL 5.1.17.

   *  `innodb_support_xa'

     When set to `ON' or 1 (the default), this variable enables
     `InnoDB' support for two-phase commit in XA transactions. Enabling
     `innodb_support_xa' causes an extra disk flush for transaction
     preparation.

     If you do not wish to use XA, you can disable this variable by
     setting it to `OFF' or 0 to reduce the number of disk flushes and
     get better `InnoDB' performance.

     Setting `innodb_support_xa' to `ON' or 1 on a replication master
     -- or on any MySQL server where binary logging is in use --
     ensures that the binary log does not get out of sync compared to
     the table data.

   *  `innodb_sync_spin_loops'

     The number of times a thread waits for an `InnoDB' mutex to be
     freed before the thread is suspended.

   *  `innodb_table_locks'

     If `AUTOCOMMIT=0', `InnoDB' honors `LOCK TABLES'; MySQL does not
     return from `LOCK TABLE .. WRITE' until all other threads have
     released all their locks to the table. The default value of
     `innodb_table_locks' is 1, which means that `LOCK TABLES' causes
     InnoDB to lock a table internally if `AUTOCOMMIT=0'.

   *  `innodb_thread_concurrency'

     `InnoDB' tries to keep the number of operating system threads
     concurrently inside `InnoDB' less than or equal to the limit given
     by this variable. Once the number of threads reaches this limit,
     additional threads are placed into a wait state within a FIFO
     queue for execution. Threads waiting for locks are not counted in
     the number of concurrently executing threads.

     The correct value for this variable is dependent on environment
     and workload. You will need to try a range of different values to
     determine what value works for your application.

     The range of this variable is 0 to 1000. A value of 20 or higher
     is interpreted as infinite concurrency before MySQL 5.1.12. From
     5.1.12 on, you can disable thread concurrency checking by setting
     the value to 0, which allows InnoDB to create as many threads as
     it needs.

     The default value is 20 before MySQL 5.1.11, and 8 from 5.1.11 on.

   *  `innodb_thread_sleep_delay'

     How long `InnoDB' threads sleep before joining the `InnoDB' queue,
     in microseconds.  The default value is 10,000. A value of 0
     disables sleep.

   * `sync_binlog'

     If the value of this variable is positive, the MySQL server
     synchronizes its binary log to disk (`fdatasync()') after every
     `sync_binlog' writes to this binary log. Note that there is one
     write to the binary log per statement if in autocommit mode, and
     otherwise one write per transaction. The default value is 0 which
     does no synchronizing to disk. A value of 1 is the safest choice,
     because in the event of a crash you lose at most one
     statement/transaction from the binary log; however, it is also the
     slowest choice (unless the disk has a battery-backed cache, which
     makes synchronization very fast).


File: manual.info,  Node: innodb-init,  Next: using-innodb-tables,  Prev: innodb-parameters,  Up: innodb

13.5.5 Creating the `InnoDB' Tablespace
---------------------------------------

* Menu:

* error-creating-innodb::        Dealing with `InnoDB' Initialization Problems

Suppose that you have installed MySQL and have edited your option file
so that it contains the necessary `InnoDB' configuration parameters.
Before starting MySQL, you should verify that the directories you have
specified for `InnoDB' data files and log files exist and that the
MySQL server has access rights to those directories.  `InnoDB' does not
create directories, only files.  Check also that you have enough disk
space for the data and log files.

It is best to run the MySQL server `mysqld' from the command prompt
when you first start the server with `InnoDB' enabled, not from the
`mysqld_safe' wrapper or as a Windows service.  When you run from a
command prompt you see what `mysqld' prints and what is happening. On
Unix, just invoke `mysqld'. On Windows, use the `--console' option.

When you start the MySQL server after initially configuring `InnoDB' in
your option file, `InnoDB' creates your data files and log files, and
prints something like this:

     InnoDB: The first specified datafile /home/heikki/data/ibdata1
     did not exist:
     InnoDB: a new database to be created!
     InnoDB: Setting file /home/heikki/data/ibdata1 size to 134217728
     InnoDB: Database physically writes the file full: wait...
     InnoDB: datafile /home/heikki/data/ibdata2 did not exist:
     new to be created
     InnoDB: Setting file /home/heikki/data/ibdata2 size to 262144000
     InnoDB: Database physically writes the file full: wait...
     InnoDB: Log file /home/heikki/data/logs/ib_logfile0 did not exist:
     new to be created
     InnoDB: Setting log file /home/heikki/data/logs/ib_logfile0 size
     to 5242880
     InnoDB: Log file /home/heikki/data/logs/ib_logfile1 did not exist:
     new to be created
     InnoDB: Setting log file /home/heikki/data/logs/ib_logfile1 size
     to 5242880
     InnoDB: Doublewrite buffer not found: creating new
     InnoDB: Doublewrite buffer created
     InnoDB: Creating foreign key constraint system tables
     InnoDB: Foreign key constraint system tables created
     InnoDB: Started
     mysqld: ready for connections

At this point `InnoDB' has initialized its tablespace and log files.
You can connect to the MySQL server with the usual MySQL client
programs like `mysql'.  When you shut down the MySQL server with
`mysqladmin shutdown', the output is like this:

     010321 18:33:34  mysqld: Normal shutdown
     010321 18:33:34  mysqld: Shutdown Complete
     InnoDB: Starting shutdown...
     InnoDB: Shutdown completed

You can look at the data file and log directories and you see the files
created there. When MySQL is started again, the data files and log
files have been created already, so the output is much briefer:

     InnoDB: Started
     mysqld: ready for connections

If you add the `innodb_file_per_table' option to `my.cnf', `InnoDB'
stores each table in its own `.ibd' file in the same MySQL database
directory where the `.frm' file is created. See *Note
multiple-tablespaces::.


File: manual.info,  Node: error-creating-innodb,  Prev: innodb-init,  Up: innodb-init

13.5.5.1 Dealing with `InnoDB' Initialization Problems
......................................................

If `InnoDB' prints an operating system error during a file operation,
usually the problem has one of the following causes:

   * You did not create the `InnoDB' data file directory or the
     `InnoDB' log directory.

   * `mysqld' does not have access rights to create files in those
     directories.

   * `mysqld' cannot read the proper `my.cnf' or `my.ini' option file,
     and consequently does not see the options that you specified.

   * The disk is full or a disk quota is exceeded.

   * You have created a subdirectory whose name is equal to a data file
     that you specified, so the name cannot be used as a filename.

   * There is a syntax error in the `innodb_data_home_dir' or
     `innodb_data_file_path' value.

If something goes wrong when `InnoDB' attempts to initialize its
tablespace or its log files, you should delete all files created by
`InnoDB'. This means all `ibdata' files and all `ib_logfile' files. In
case you have already created some `InnoDB' tables, delete the
corresponding `.frm' files for these tables (and any `.ibd' files if
you are using multiple tablespaces) from the MySQL database directories
as well. Then you can try the `InnoDB' database creation again. It is
best to start the MySQL server from a command prompt so that you see
what is happening.


File: manual.info,  Node: using-innodb-tables,  Next: adding-and-removing,  Prev: innodb-init,  Up: innodb

13.5.6 Creating and Using `InnoDB' Tables
-----------------------------------------

* Menu:

* innodb-transactions-with-different-apis::  How to Use Transactions in `InnoDB' with Different APIs
* converting-tables-to-innodb::  Converting `MyISAM' Tables to `InnoDB'
* innodb-auto-increment-handling::  How `AUTO_INCREMENT' Handling Works in `InnoDB'
* innodb-foreign-key-constraints::  `FOREIGN KEY' Constraints
* innodb-and-mysql-replication::  `InnoDB' and MySQL Replication

To create an `InnoDB' table, specify an `ENGINE = InnoDB' option in the
`CREATE TABLE' statement:

     CREATE TABLE customers (a INT, b CHAR (20), INDEX (a)) ENGINE=InnoDB;

The statement creates a table and an index on column `a' in the
`InnoDB' tablespace that consists of the data files that you specified
in `my.cnf'. In addition, MySQL creates a file `customers.frm' in the
`test' directory under the MySQL database directory. Internally,
`InnoDB' adds an entry for the table to its own data dictionary. The
entry includes the database name. For example, if `test' is the
database in which the `customers' table is created, the entry is for
`'test/customers''.  This means you can create a table of the same name
`customers' in some other database, and the table names do not collide
inside `InnoDB'.

You can query the amount of free space in the `InnoDB' tablespace by
issuing a `SHOW TABLE STATUS' statement for any `InnoDB' table. The
amount of free space in the tablespace appears in the `Comment' section
in the output of `SHOW TABLE STATUS'. For example:

     SHOW TABLE STATUS FROM test LIKE 'customers'

Note that the statistics `SHOW' displays for `InnoDB' tables are only
approximate. They are used in SQL optimization. Table and index
reserved sizes in bytes are accurate, though.


File: manual.info,  Node: innodb-transactions-with-different-apis,  Next: converting-tables-to-innodb,  Prev: using-innodb-tables,  Up: using-innodb-tables

13.5.6.1 How to Use Transactions in `InnoDB' with Different APIs
................................................................

By default, each client that connects to the MySQL server begins with
autocommit mode enabled, which automatically commits every SQL
statement as you execute it. To use multiple-statement transactions,
you can switch autocommit off with the SQL statement `SET AUTOCOMMIT =
0' and use `COMMIT' and `ROLLBACK' to commit or roll back your
transaction. If you want to leave autocommit on, you can enclose your
transactions within `START TRANSACTION' and either `COMMIT' or
`ROLLBACK'. The following example shows two transactions. The first is
committed; the second is rolled back.

     shell> mysql test

     mysql> CREATE TABLE CUSTOMER (A INT, B CHAR (20), INDEX (A))
         -> ENGINE=InnoDB;
     Query OK, 0 rows affected (0.00 sec)
     mysql> START TRANSACTION;
     Query OK, 0 rows affected (0.00 sec)
     mysql> INSERT INTO CUSTOMER VALUES (10, 'Heikki');
     Query OK, 1 row affected (0.00 sec)
     mysql> COMMIT;
     Query OK, 0 rows affected (0.00 sec)
     mysql> SET AUTOCOMMIT=0;
     Query OK, 0 rows affected (0.00 sec)
     mysql> INSERT INTO CUSTOMER VALUES (15, 'John');
     Query OK, 1 row affected (0.00 sec)
     mysql> ROLLBACK;
     Query OK, 0 rows affected (0.00 sec)
     mysql> SELECT * FROM CUSTOMER;
     +------+--------+
     | A    | B      |
     +------+--------+
     |   10 | Heikki |
     +------+--------+
     1 row in set (0.00 sec)
     mysql>

In APIs such as PHP, Perl DBI, JDBC, ODBC, or the standard C call
interface of MySQL, you can send transaction control statements such as
`COMMIT' to the MySQL server as strings just like any other SQL
statements such as `SELECT' or `INSERT'. Some APIs also offer separate
special transaction commit and rollback functions or methods.


File: manual.info,  Node: converting-tables-to-innodb,  Next: innodb-auto-increment-handling,  Prev: innodb-transactions-with-different-apis,  Up: using-innodb-tables

13.5.6.2 Converting `MyISAM' Tables to `InnoDB'
...............................................

Important: Do not convert MySQL system tables in the `mysql' database
(such as `user' or `host') to the `InnoDB' type. This is an unsupported
operation. The system tables must always be of the `MyISAM' type.

If you want all your (non-system) tables to be created as `InnoDB'
tables, you can simply add the line `default-storage-engine=innodb' to
the `[mysqld]' section of your server option file.

`InnoDB' does not have a special optimization for separate index
creation the way the `MyISAM' storage engine does. Therefore, it does
not pay to export and import the table and create indexes afterward.
The fastest way to alter a table to `InnoDB' is to do the inserts
directly to an `InnoDB' table. That is, use `ALTER TABLE ...
ENGINE=INNODB', or create an empty `InnoDB' table with identical
definitions and insert the rows with `INSERT INTO ... SELECT * FROM
...'.

If you have `UNIQUE' constraints on secondary keys, you can speed up a
table import by turning off the uniqueness checks temporarily during
the import operation:

     SET UNIQUE_CHECKS=0;
     ... IMPORT OPERATION ...
     SET UNIQUE_CHECKS=1;

For big tables, this saves a lot of disk I/O because `InnoDB' can then
use its insert buffer to write secondary index records as a batch. Be
certain that the data contains no duplicate keys.  `UNIQUE_CHECKS'
allows but does not require storage engines to ignore duplicate keys.

To get better control over the insertion process, it might be good to
insert big tables in pieces:

     INSERT INTO newtable SELECT * FROM oldtable
        WHERE yourkey > something AND yourkey <= somethingelse;

After all records have been inserted, you can rename the tables.

During the conversion of big tables, you should increase the size of
the `InnoDB' buffer pool to reduce disk I/O. Do not use more than 80%
of the physical memory, though.  You can also increase the sizes of the
`InnoDB' log files.

Make sure that you do not fill up the tablespace: `InnoDB' tables
require a lot more disk space than `MyISAM' tables. If an `ALTER TABLE'
operation runs out of space, it starts a rollback, and that can take
hours if it is disk-bound. For inserts, `InnoDB' uses the insert buffer
to merge secondary index records to indexes in batches. That saves a
lot of disk I/O. For rollback, no such mechanism is used, and the
rollback can take 30 times longer than the insertion.

In the case of a runaway rollback, if you do not have valuable data in
your database, it may be advisable to kill the database process rather
than wait for millions of disk I/O operations to complete. For the
complete procedure, see *Note forcing-recovery::.


File: manual.info,  Node: innodb-auto-increment-handling,  Next: innodb-foreign-key-constraints,  Prev: converting-tables-to-innodb,  Up: using-innodb-tables

13.5.6.3 How `AUTO_INCREMENT' Handling Works in `InnoDB'
........................................................

* Menu:

* innodb-auto-increment-traditional::  `Traditional' `InnoDB' Auto-Increment Locking
* innodb-auto-increment-configurable::  Configurable `InnoDB' Auto-Increment Locking

Beginning with MySQL 5.1.22, `InnoDB' provides a locking strategy that
significantly improves scalability and performance of SQL statements
that add rows to tables with `AUTO_INCREMENT' columns. This section
provides background information on the original (`traditional')
implementation of auto-increment locking in `InnoDB', explains the
configurable locking mechanism, documents the parameter for configuring
the mechanism, and describes its behavior and interaction with
replication.


File: manual.info,  Node: innodb-auto-increment-traditional,  Next: innodb-auto-increment-configurable,  Prev: innodb-auto-increment-handling,  Up: innodb-auto-increment-handling

13.5.6.4 `Traditional' `InnoDB' Auto-Increment Locking
......................................................

The original implementation of auto-increment handling in `InnoDB' uses
the following strategy to prevent problems when using the binary log
for statement-based replication or for certain recovery scenarios.

If you specify an `AUTO_INCREMENT' column for an `InnoDB' table, the
table handle in the `InnoDB' data dictionary contains a special counter
called the auto-increment counter that is used in assigning new values
for the column. This counter is stored only in main memory, not on disk.

`InnoDB' uses the following algorithm to initialize the auto-increment
counter for a table `t' that contains an `AUTO_INCREMENT' column named
`ai_col': After a server startup, for the first insert into a table `t',
`InnoDB' executes the equivalent of this statement:

     SELECT MAX(ai_col) FROM t FOR UPDATE;

`InnoDB' increments by one the value retrieved by the statement and
assigns it to the column and to the auto-increment counter for the
table. If the table is empty, `InnoDB' uses the value `1'. If a user
invokes a `SHOW TABLE STATUS' statement that displays output for the
table `t' and the auto-increment counter has not been initialized,
`InnoDB' initializes but does not increment the value and stores it for
use by later inserts. This initialization uses a normal
exclusive-locking read on the table and the lock lasts to the end of the
transaction.

`InnoDB' follows the same procedure for initializing the auto-increment
counter for a freshly created table.

After the auto-increment counter has been initialized, if a user does
not explicitly specify a value for an `AUTO_INCREMENT' column, `InnoDB'
increments the counter by one and assigns the new value to the column.
If the user inserts a row that explicitly specifies the column value,
and the value is bigger than the current counter value, the counter is
set to the specified column value.

When accessing the auto-increment counter, `InnoDB' uses a special
table-level `AUTO-INC' lock that it keeps to the end of the current SQL
statement, not to the end of the transaction.  The special lock release
strategy was introduced to improve concurrency for inserts into a table
containing an `AUTO_INCREMENT' column. Nevertheless, two transactions
cannot have the `AUTO-INC' lock on the same table simultaneously, which
can have a performance impact if the `AUTO-INC' lock is held for a long
time. That might be the case for a statement such as `INSERT INTO t1
... SELECT ... FROM t2' that inserts all rows from one table into
another.

`InnoDB' uses the in-memory auto-increment counter as long as the
server runs. When the server is stopped and restarted, `InnoDB'
reinitializes the counter for each table for the first `INSERT' to the
table, as described earlier.

You may see gaps in the sequence of values assigned to the
`AUTO_INCREMENT' column if you roll back transactions that have
generated numbers using the counter.

If a user specifies `NULL' or `0' for the `AUTO_INCREMENT' column in an
`INSERT', `InnoDB' treats the row as if the value had not been
specified and generates a new value for it.

The behavior of the auto-increment mechanism is not defined if a user
assigns a negative value to the column or if the value becomes bigger
than the maximum integer that can be stored in the specified integer
type.

An `AUTO_INCREMENT' column must appear as the first column in an index
on an `InnoDB' table.

`InnoDB' supports the `AUTO_INCREMENT = N' table option in `CREATE
TABLE' and `ALTER TABLE' statements, to set the initial counter value
or alter the current counter value. The effect of this option is
canceled by a server restart, for reasons discussed earlier in this
section.


File: manual.info,  Node: innodb-auto-increment-configurable,  Prev: innodb-auto-increment-traditional,  Up: innodb-auto-increment-handling

13.5.6.5 Configurable `InnoDB' Auto-Increment Locking
.....................................................

As described in the previous section, `InnoDB' uses a special lock
called the table-level `AUTO-INC' lock for inserts into tables with
`AUTO_INCREMENT' columns. This lock is normally held to the end of the
statement (not to the end of the transaction), to ensure that
auto-increment numbers are assigned in a predictable and repeatable
order for a given sequence of `INSERT' statements.

In the case of statement-based replication, this means that when a SQL
statement is replicated on a slave server, the same values are used for
the auto-increment column as on the master server. The result of
execution of multiple `INSERT' statements is deterministic, and the
slave reproduces the same data as on the master. If auto-increment
values generated by multiple `INSERT' statements were interleaved, the
result of two concurrent `INSERT' statements would be
non-deterministic, and could not reliably be propagated to a slave
server using statement-based replication.

To make this clear, consider an example that uses this table:

     CREATE TABLE t1 (
       c1 INT(11) NOT NULL AUTO_INCREMENT,
       c2 VARCHAR(10) DEFAULT NULL,
       PRIMARY KEY (c1)
     ) ENGINE=InnoDB;

Suppose that there are two transactions running, each inserting rows
into a table with an `AUTO_INCREMENT' column. One transaction is using
an `INSERT ... SELECT' statement that inserts 1000 rows, and another is
using a simple `INSERT' statement that inserts one row:

     Tx1: INSERT INTO t1 (c2) SELECT 1000 rows from another table ...
     Tx2: INSERT INTO t1 (c2) VALUES ('xxx');

`InnoDB' cannot tell in advance how many rows will be retrieved from
the `SELECT' in the `INSERT' statement in Tx1, and it assigns the
auto-increment values one at a time as the statement proceeds.  With a
table-level lock, held to the end of the statement, only one `INSERT'
statement referring to table `t1' can execute at a time, and the
generation of auto-increment numbers by different statements is not
interleaved. The auto-increment value generated by the Tx1 `INSERT ...
SELECT' statement will be consecutive, and the (single) auto-increment
value used by the `INSERT' statement in Tx2 will either be smaller or
larger than all those used for Tx1, depending on which statement
executes first.

As long as the SQL statements execute in the same order when replayed
from the binary log (when using statement-based replication, or in
recovery scenarios), the results will be the same as they were when Tx1
and Tx2 first ran. Thus, table-level locks held until the end of a
statement make `INSERT' statements using auto-increment safe for use
with statement-based replication. However, those locks limit
concurrency and scalability when multiple transactions are executing
insert statements at the same time.

In the preceding example, if there were no table-level lock, the value
of the auto-increment column used for the `INSERT' in Tx2 depends on
precisely when the statement executes. If the `INSERT' of Tx2 executes
while the `INSERT' of Tx1 is running (rather than before it starts or
after it completes), the specific auto-increment values assigned by the
two `INSERT' statements are non-deterministic, and may vary from run to
run.

As of MySQL 5.1.22, `InnoDB' can avoid using the table-level `AUTO-INC'
lock for a class of `INSERT' statements where the number of rows is
known in advance, and still preserve deterministic execution and safety
for statement-based replication. Further, if you are not using the
binary log to replay SQL statements as part of recovery or replication,
you can entirely eliminate use of the table-level `AUTO-INC' lock for
even greater concurrency and performance--at the cost of permitting
gaps in auto-increment numbers assigned by a statement and potentially
having the numbers assigned by concurrently executing statements
interleaved.

For `INSERT' statements where the number of rows to be inserted is
known at the beginning of processing the statement, `InnoDB' quickly
allocates the required number of auto-increment values without taking
any lock, but only if there is no concurrent session already holding
the table-level `AUTO-INC' lock (because that other statement will be
allocating auto-increment values one-by-one as it proceeds). More
precisely, such an `INSERT' statement obtains auto-increment values
under the control of a mutex (a light-weight lock) that is _not_ held
until the statement completes, but only for the duration of the
allocation process.

This new locking scheme allows much greater scalability, but it does
introduce some subtle differences in how auto-increment values are
assigned compared to the original mechanism. To describe the way
auto-increment works in `InnoDB', the following discussion defines some
terms, and explains how `InnoDB' behaves using different settings of
the new `innodb_autoinc_lock_mode' configuration parameter. Additional
considerations are described following the explanation of
auto-increment locking behavior.

First, some definitions:

   * ``INSERT'-like' statements

     All statements that generate new rows in a table, including
     `INSERT', `INSERT ...  SELECT', `REPLACE', `REPLACE ... SELECT',
     and `LOAD DATA'.

   * `Simple inserts'

     Statements for which the number of rows to be inserted can be
     determined in advance (when the statement is initially processed).
     This includes single-row and multiple-row `INSERT' and `REPLACE'
     statements that do not have a nested subquery, but not `INSERT ...
     ON DUPLICATE KEY UPDATE'.

   * `Bulk inserts'

     Statements for which the number of rows to be inserted (and the
     number of required auto-increment values) is not known in advance.
     This includes `INSERT ...  SELECT', `REPLACE ... SELECT', and
     `LOAD DATA' statements.  `InnoDB' will assign new values for the
     `AUTO_INCREMENT' column one at a time as each row is processed.

   * `Mixed-mode inserts'

     These are `simple insert' statements that specify the
     auto-increment value for some (but not all) of the new rows. An
     example follows, where `c1' is an `AUTO_INCREMENT' column of table
     `t1':

          INSERT INTO t1 (c1,c2) VALUES (1,'a'), (NULL,'b'), (5,'c'), (NULL,'d');

     Another type of `mixed-mode insert' is `INSERT ... ON DUPLICATE
     KEY UPDATE', which in the worst case is in effect an `INSERT'
     followed by a `UPDATE', where the allocated value for the the
     `AUTO_INCREMENT' column may or may not be used during the update
     phase.

Beginning with MySQL 5.1.22, there is a new configuration parameter
that controls how `InnoDB' uses locking when generating values for
`AUTO_INCREMENT' columns. This parameter can be set using the
`--innodb-autoinc-lock-mode' option at `mysqld' startup.

In general, if you encounter problems with the way auto-increment works
(which will most likely involve replication), you can force use of the
original behavior by setting the lock mode to 0.

There are three possible settings for the `innodb_autoinc_lock_mode'
parameter:

   * `innodb_autoinc_lock_mode = 0' (`traditional' lock mode)

     This lock mode provides the same behavior as before
     `innodb_autoinc_lock_mode' existed. For all ``INSERT'-like'
     statements, a special table-level `AUTO-INC' lock is obtained and
     held to the end of the statement. This assures that the
     auto-increment values assigned by any given statement are
     consecutive (although `gaps' can exist within a table if a
     transaction that generated auto-increment values is rolled back,
     as discussed later).

     This lock mode is provided only for backward compatibility and
     performance testing. There is little reason to use this lock mode
     unless you use `mixed-mode inserts' and care about the important
     difference in semantics described later.

   * `innodb_autoinc_lock_mode = 1' (`consecutive' lock mode)

     This is the default lock mode. In this mode, `bulk inserts' use
     the special `AUTO-INC' table-level lock and hold it until the end
     of the statement. This applies to all `INSERT ... SELECT',
     `REPLACE ...  SELECT', and `LOAD DATA' statements. Only one
     statement holding the `AUTO-INC' lock can execute at a time.

     With this lock mode, `simple inserts' (only) use a new locking
     model where a light-weight mutex is used during the allocation of
     auto-increment values, and no table-level `AUTO-INC' lock is used,
     unless an `AUTO-INC' lock is held by another transaction. If
     another transaction does hold an `AUTO-INC' lock, a `simple
     insert' waits for the `AUTO-INC' lock, as if it too were a `bulk
     insert.'

     This lock mode ensures that, in the presence of `INSERT'
     statements where the number of rows is not known in advance (and
     where auto-increment numbers are assigned as the statement
     progresses), all auto-increment values assigned by any
     ``INSERT'-like' statement are consecutive, and operations are safe
     for statement-based replication.

     Simply put, the important impact of this lock mode is
     significantly better scalability. This mode is safe for use with
     statement-based replication. Further, as with `traditional' lock
     mode, auto-increment numbers assigned by any given statement are
     _consecutive_. In this mode, there is _no change_ in semantics
     compared to `traditional' mode for any statement that uses
     auto-increment, with one important exception.

     The exception is for `mixed-mode inserts', where the user provides
     explicit values for an `AUTO_INCREMENT' column for some, but not
     all, rows in a multiple-row `simple insert.' For such inserts,
     `InnoDB' will allocate more auto-increment values than the number
     of rows to be inserted. However, all values automatically assigned
     are consecutively generated (and thus higher than) the
     auto-increment value generated by the most recently executed
     previous statement. `Excess' numbers are lost.

     A similar situation exists if you use `INSERT ...  ON DUPLICATE
     KEY UPDATE'. This statement is also classified as a `mixed-mode
     insert' since an auto-increment value is not necessarily generated
     for each row. Because `InnoDB' allocates the auto-increment value
     before the insert is actually attempted, it cannot know whether an
     inserted value will be a duplicate of an existing value and thus
     cannot know whether the auto-increment value it generates will be
     used for a new row. Therefore, if you are using statement-based
     replication, you must either avoid `INSERT ... ON DUPLICATE KEY
     UPDATE' or use `innodb_autoinc_lock_mode = 0' (`traditional' lock
     mode).

   * `innodb_autoinc_lock_mode = 2' (`interleaved' lock mode)

     In this lock mode, no ``INSERT'-like' statements use the
     table-level `AUTO-INC' lock, and multiple statements can execute
     at the same time. This is the fastest and most scalable lock mode,
     but it is _not safe_ when using statement-based replication or
     recovery scenarios when SQL statements are replayed from the
     binary log.

     In this lock mode, auto-increment values are guaranteed to be
     unique and monotonically increasing across all concurrently
     executing ``INSERT'-like' statements.  However, because multiple
     statements can be generating numbers at the same time (that is,
     allocation of numbers is _interleaved_ across statements), the
     values generated for the rows inserted by any given statement may
     not be consecutive.

     If the only statements executing are `simple inserts' where the
     number of rows to be inserted is known ahead of time, there will
     be no gaps in the numbers generated for a single statement, except
     for `mixed-mode inserts.' However, when `bulk inserts' are
     executed, there may be gaps in the auto-increment values assigned
     by any given statement.

The auto-increment locking modes provided by `innodb_autoinc_lock_mode'
have several usage implications:

   * Using auto-increment with replication

     If you are using statement-based replication, you should set
     `innodb_autoinc_lock_mode' to 0 or 1 and use the same value on the
     master and its slaves.  Auto-increment values are not ensured to
     be the same on the slaves as on the master if you use
     `innodb_autoinc_lock_mode' = 2 (`interleaved') or configurations
     where the master and slaves do not use the same lock mode.

     If you are using row-based replication, all of the auto-increment
     lock modes are safe. Row-based replication is not sensitive to the
     order of execution of the SQL statements.

   * `Lost' auto-increment values and sequence gaps

     In all lock modes (0, 1, and 2), if a transaction that generated
     auto-increment values rolls back, those auto-increment values are
     `lost.' Once a value is generated for an auto-increment column, it
     cannot be rolled back, whether or not the ``INSERT'-like'
     statement is completed, and whether or not the containing
     transaction is rolled back. Such lost values are not reused. Thus,
     there may be gaps in the values stored in an `AUTO_INCREMENT'
     column of a table.

   * Auto-increment values assigned by `mixed-mode inserts'

     Consider a `mixed-mode insert,' where a `simple insert' specifies
     the auto-increment value for some (but not all) resulting rows.
     Such a statement will behave differently in lock modes 0, 1, and
     2. For example, assume `c1' is an `AUTO_INCREMENT' column of table
     `t1', and that the most recent automatically generated sequence
     number is 100. Consider the following `mixed-mode insert'
     statement:

          INSERT INTO t1 (c1,c2) VALUES (1,'a'), (NULL,'b'), (5,'c'), (NULL,'d');

     With `innodb_autoinc_lock_mode' set to 0 (`traditional'), the four
     new rows will be:

          +-----+------+
          | c1  | c2   |
          +-----+------+
          |   1 | a    |
          | 101 | b    |
          |   5 | c    |
          | 102 | d    |
          +-----+------+

     The next available auto-increment value will be 103 because the
     auto-increment values are allocated one at a time, not all at once
     at the beginning of statement execution. This result is true
     whether or not there are concurrently executing ``INSERT'-like'
     statements (of any type).

     With `innodb_autoinc_lock_mode' set to 1 (`consecutive'), the four
     new rows will also be:

          +-----+------+
          | c1  | c2   |
          +-----+------+
          |   1 | a    |
          | 101 | b    |
          |   5 | c    |
          | 102 | d    |
          +-----+------+

     However, in this case, the next available auto-increment value
     will be 105, not 103 because four auto-increment values are
     allocated at the time the statement is processed, but only two are
     used. This result is true whether or not there are concurrently
     executing ``INSERT'-like' statements (of any type).

     With `innodb_autoinc_lock_mode' set to mode 2 (`interleaved'), the
     four new rows will be:

          +-----+------+
          | c1  | c2   |
          +-----+------+
          |   1 | a    |
          |   X | b    |
          |   5 | c    |
          |   Y | d    |
          +-----+------+

     The values of X and Y will be unique and larger than any
     previously generated rows. However, the specific values of X and Y
     will depend on the number of auto-increment values generated by
     concurrently executing statements.

     Finally, consider the following statement, issued when the
     most-recently generated sequence number was the value 4:

          INSERT INTO t1 (c1,c2) VALUES (1,'a'), (NULL,'b'), (5,'c'), (NULL,'d');

     With any `innodb_autoinc_lock_mode' setting, this statement will
     generate a duplicate-key error 23000 (`Can't write; duplicate key
     in table') because 5 will be allocated for the row `(NULL, 'b')'
     and insertion of the row `(5, 'c')' will fail.

   * Gaps in auto-increment values for `bulk inserts'

     With `innodb_autoinc_lock_mode' set to 0 (`traditional') or 1
     (`consecutive'), the auto-increment values generated by any given
     statement will be consecutive, without gaps, because the
     table-level `AUTO-INC' lock is held until the end of the
     statement, and only one such statement can execute at a time.

     With `innodb_autoinc_lock_mode' set to 2 (`interleaved'), there
     may be gaps in the auto-increment values generated by `bulk
     inserts,' but only if there are concurrently executing
     ``INSERT'-like' statements.


File: manual.info,  Node: innodb-foreign-key-constraints,  Next: innodb-and-mysql-replication,  Prev: innodb-auto-increment-handling,  Up: using-innodb-tables

13.5.6.6 `FOREIGN KEY' Constraints
..................................

`InnoDB' supports foreign key constraints. The syntax for a foreign key
constraint definition in `InnoDB' looks like this:

     [CONSTRAINT [SYMBOL]] FOREIGN KEY
         [INDEX_NAME] (INDEX_COL_NAME, ...)
         REFERENCES TBL_NAME (INDEX_COL_NAME,...)
         [ON DELETE REFERENCE_OPTION]
         [ON UPDATE REFERENCE_OPTION]

     REFERENCE_OPTION:
         RESTRICT | CASCADE | SET NULL | NO ACTION

INDEX_NAME represents a foreign key ID. If given, this is ignored if an
index for the foreign key is defined explicitly. Otherwise, if `InnoDB'
creates an index for the foreign key, it uses INDEX_NAME for the index
name.

Foreign keys definitions are subject to the following conditions:

   * Both tables must be `InnoDB' tables and they must not be
     `TEMPORARY' tables.

   * Corresponding columns in the foreign key and the referenced key
     must have similar internal data types inside `InnoDB' so that they
     can be compared without a type conversion. _The size and sign of
     integer types must be the same_. The length of string types need
     not be the same. For non-binary (character) string columns, the
     character set and collation must be the same.

   * In the referencing table, there must be an index where the foreign
     key columns are listed as the _first_ columns in the same order.
     Such an index is created on the referencing table automatically if
     it does not exist. INDEX_NAME, if given, is used as described
     previously.

   * `InnoDB' allows a foreign key to reference any index column or
     group of columns. However, in the referenced table, there must be
     an index where the referenced columns are listed as the _first_
     columns in the same order.

   * Index prefixes on foreign key columns are not supported. One
     consequence of this is that `BLOB' and `TEXT' columns cannot be
     included in a foreign key, because indexes on those columns must
     always include a prefix length.

   * If the `CONSTRAINT SYMBOL' clause is given, the SYMBOL value must
     be unique in the database. If the clause is not given, `InnoDB'
     creates the name automatically.

`InnoDB' rejects any `INSERT' or `UPDATE' operation that attempts to
create a foreign key value in a child table if there is no a matching
candidate key value in the parent table. The action `InnoDB' takes for
any `UPDATE' or `DELETE' operation that attempts to update or delete a
candidate key value in the parent table that has some matching rows in
the child table is dependent on the _referential action_ specified
using `ON UPDATE' and `ON DELETE' subclauses of the `FOREIGN KEY'
clause. When the user attempts to delete or update a row from a parent
table, and there are one or more matching rows in the child table,
`InnoDB' supports five options regarding the action to be taken. If `ON
DELETE' or `ON UPDATE' are not specified, the default action is
`RESTRICT'.

   * `CASCADE': Delete or update the row from the parent table and
     automatically delete or update the matching rows in the child
     table. Both `ON DELETE CASCADE' and `ON UPDATE CASCADE' are
     supported. Between two tables, you should not define several `ON
     UPDATE CASCADE' clauses that act on the same column in the parent
     table or in the child table.

   * `SET NULL': Delete or update the row from the parent table and set
     the foreign key column or columns in the child table to `NULL'.
     This is valid only if the foreign key columns do not have the `NOT
     NULL' qualifier specified. Both `ON DELETE SET NULL' and `ON
     UPDATE SET NULL' clauses are supported.

     If you specify a `SET NULL' action, _make sure that you have not
     declared the columns in the child table as `NOT NULL'_.

   * `NO ACTION': In standard SQL, `NO ACTION' means _no action_ in the
     sense that an attempt to delete or update a primary key value is
     not allowed to proceed if there is a related foreign key value in
     the referenced table.  `InnoDB' rejects the delete or update
     operation for the parent table.

   * `RESTRICT': Rejects the delete or update operation for the parent
     table. Specifying `RESTRICT' (or `NO ACTION') is the same as
     omitting the `ON DELETE' or `ON UPDATE' clause.  (Some database
     systems have deferred checks, and `NO ACTION' is a deferred check.
     In MySQL, foreign key constraints are checked immediately, so `NO
     ACTION' is the same as `RESTRICT'.)

   * `SET DEFAULT': This action is recognized by the parser, but
     `InnoDB' rejects table definitions containing `ON DELETE SET
     DEFAULT' or `ON UPDATE SET DEFAULT' clauses.

Note that `InnoDB' supports foreign key references within a table. In
these cases, `child table records' really refers to dependent records
within the same table.

`InnoDB' requires indexes on foreign keys and referenced keys so that
foreign key checks can be fast and not require a table scan. The index
on the foreign key is created automatically if no index on the key
columns exists. This is in contrast to some older versions, in which
indexes had to be created explicitly or the creation of foreign key
constraints would fail.

If MySQL reports an error number 1005 from a `CREATE TABLE' statement,
and the error message refers to errno 150, table creation failed
because a foreign key constraint was not correctly formed. Similarly,
if an `ALTER TABLE' fails and it refers to errno 150, that means a
foreign key definition would be incorrectly formed for the altered
table. You can use `SHOW ENGINE INNODB STATUS' to display a detailed
explanation of the most recent `InnoDB' foreign key error in the server.

*Important*:

For users familiar with the ANSI/ISO SQL Standard, please note that no
storage engine, including `InnoDB', recognizes or enforces the `MATCH'
clause used in referential integrity constraint definitions. Use of an
explicit `MATCH' clause will not have the specified effect, and also
causes `ON DELETE' and `ON UPDATE' clauses to be ignored. For these
reasons, specifying `MATCH' should be avoided.

The `MATCH' clause in the SQL standard controls how `NULL' values in a
composite (multiple-column) foreign key are handled when comparing to a
primary key. `InnoDB' essentially implements the semantics defined by
`MATCH SIMPLE', which allow a foreign key to be all or partially
`NULL'. In that case, the (child table) row containing such a foreign
key is allowed to be inserted, and does not match any row in the
referenced (parent) table. It is possible to implement other semantics
using triggers.

Additionally, MySQL and `InnoDB' require that the referenced columns be
indexed for performance. However, the system does not enforce a
requirement that the referenced columns be `UNIQUE' or be declared `NOT
NULL'. The handling of foreign key references to non-unique keys or
keys that contain `NULL' values is not well defined for operations such
as `UPDATE' or `DELETE CASCADE'. You are advised to use foreign keys
that reference only `UNIQUE' and `NOT NULL' keys.

Furthermore, `InnoDB' does not recognize or support `inline `REFERENCES'
specifications' (as defined in the SQL standard) where the references
are defined as part of the column specification. `InnoDB' accepts
`REFERENCES' clauses only when specified as part of a separate `FOREIGN
KEY' specification. For other storage engines, MySQL Server parses and
ignores foreign key specifications.

*Note*:

Currently, triggers are not activated by cascaded foreign key actions.

You cannot create a table with a column name that matches the name of
an internal InnoDB column (including `DB_ROW_ID', `DB_TRX_ID',
`DB_ROLL_PTR' and `DB_MIX_ID'). In versions of MySQL before 5.1.10 this
would cause a crash, since 5.1.10 the server will report error 1005 and
refers to `errno' -1 in the error message.

*Deviation from SQL standards*: If there are several rows in the parent
table that have the same referenced key value, `InnoDB' acts in foreign
key checks as if the other parent rows with the same key value do not
exist. For example, if you have defined a `RESTRICT' type constraint,
and there is a child row with several parent rows, `InnoDB' does not
allow the deletion of any of those parent rows.

`InnoDB' performs cascading operations through a depth-first algorithm,
based on records in the indexes corresponding to the foreign key
constraints.

*Deviation from SQL standards*: A `FOREIGN KEY' constraint that
references a non-`UNIQUE' key is not standard SQL. It is an `InnoDB'
extension to standard SQL.

*Deviation from SQL standards*: If `ON UPDATE CASCADE' or `ON UPDATE
SET NULL' recurses to update the _same table_ it has previously updated
during the cascade, it acts like `RESTRICT'. This means that you cannot
use self-referential `ON UPDATE CASCADE' or `ON UPDATE SET NULL'
operations. This is to prevent infinite loops resulting from cascaded
updates. A self-referential `ON DELETE SET NULL', on the other hand, is
possible, as is a self-referential `ON DELETE CASCADE'. Cascading
operations may not be nested more than 15 levels deep.

*Deviation from SQL standards*: Like MySQL in general, in an SQL
statement that inserts, deletes, or updates many rows, `InnoDB' checks
`UNIQUE' and `FOREIGN KEY' constraints row-by-row. According to the SQL
standard, the default behavior should be deferred checking. That is,
constraints are only checked after the _entire SQL statement_ has been
processed. Until `InnoDB' implements deferred constraint checking, some
things will be impossible, such as deleting a record that refers to
itself via a foreign key.

Here is a simple example that relates `parent' and `child' tables
through a single-column foreign key:

     CREATE TABLE parent (id INT NOT NULL,
                          PRIMARY KEY (id)
     ) ENGINE=INNODB;
     CREATE TABLE child (id INT, parent_id INT,
                         INDEX par_ind (parent_id),
                         FOREIGN KEY (parent_id) REFERENCES parent(id)
                           ON DELETE CASCADE
     ) ENGINE=INNODB;

A more complex example in which a `product_order' table has foreign
keys for two other tables. One foreign key references a two-column
index in the `product' table. The other references a single-column
index in the `customer' table:

     CREATE TABLE product (category INT NOT NULL, id INT NOT NULL,
                           price DECIMAL,
                           PRIMARY KEY(category, id)) ENGINE=INNODB;
     CREATE TABLE customer (id INT NOT NULL,
                            PRIMARY KEY (id)) ENGINE=INNODB;
     CREATE TABLE product_order (no INT NOT NULL AUTO_INCREMENT,
                                 product_category INT NOT NULL,
                                 product_id INT NOT NULL,
                                 customer_id INT NOT NULL,
                                 PRIMARY KEY(no),
                                 INDEX (product_category, product_id),
                                 FOREIGN KEY (product_category, product_id)
                                   REFERENCES product(category, id)
                                   ON UPDATE CASCADE ON DELETE RESTRICT,
                                 INDEX (customer_id),
                                 FOREIGN KEY (customer_id)
                                   REFERENCES customer(id)) ENGINE=INNODB;

`InnoDB' allows you to add a new foreign key constraint to a table by
using `ALTER TABLE':

     ALTER TABLE TBL_NAME
         ADD [CONSTRAINT [SYMBOL]] FOREIGN KEY
         [INDEX_NAME] (INDEX_COL_NAME, ...)
         REFERENCES TBL_NAME (INDEX_COL_NAME,...)
         [ON DELETE REFERENCE_OPTION]
         [ON UPDATE REFERENCE_OPTION]

*Remember to create the required indexes first*. You can also add a
self-referential foreign key constraint to a table using `ALTER TABLE'.

`InnoDB' also supports the use of `ALTER TABLE' to drop foreign keys:

     ALTER TABLE TBL_NAME DROP FOREIGN KEY FK_SYMBOL;

If the `FOREIGN KEY' clause included a `CONSTRAINT' name when you
created the foreign key, you can refer to that name to drop the foreign
key.  Otherwise, the FK_SYMBOL value is internally generated by
`InnoDB' when the foreign key is created. To find out the symbol value
when you want to drop a foreign key, use the `SHOW CREATE TABLE'
statement. For example:

     mysql> SHOW CREATE TABLE ibtest11c\G
     *************************** 1. row ***************************
            Table: ibtest11c
     Create Table: CREATE TABLE `ibtest11c` (
       `A` int(11) NOT NULL auto_increment,
       `D` int(11) NOT NULL default '0',
       `B` varchar(200) NOT NULL default '',
       `C` varchar(175) default NULL,
       PRIMARY KEY  (`A`,`D`,`B`),
       KEY `B` (`B`,`C`),
       KEY `C` (`C`),
       CONSTRAINT `0_38775` FOREIGN KEY (`A`, `D`)
     REFERENCES `ibtest11a` (`A`, `D`)
     ON DELETE CASCADE ON UPDATE CASCADE,
       CONSTRAINT `0_38776` FOREIGN KEY (`B`, `C`)
     REFERENCES `ibtest11a` (`B`, `C`)
     ON DELETE CASCADE ON UPDATE CASCADE
     ) ENGINE=INNODB CHARSET=latin1
     1 row in set (0.01 sec)

     mysql> ALTER TABLE ibtest11c DROP FOREIGN KEY `0_38775`;

You cannot add a foreign key and drop a foreign key in separate clauses
of a single `ALTER TABLE' statement.  Separate statements are required.

If `ALTER TABLE' for an `InnoDB' table results in changes to column
values (for example, because a column is truncated), `InnoDB''s
`FOREIGN KEY' constraint checks do not notice possible violations
caused by changing the values.

The `InnoDB' parser allows table and column identifiers in a `FOREIGN
KEY ... REFERENCES ...' clause to be quoted within backticks.
(Alternatively, double quotes can be used if the `ANSI_QUOTES' SQL mode
is enabled.) The `InnoDB' parser also takes into account the setting of
the `lower_case_table_names' system variable.

`InnoDB' returns a table's foreign key definitions as part of the
output of the `SHOW CREATE TABLE' statement:

     SHOW CREATE TABLE TBL_NAME;

`mysqldump' also produces correct definitions of tables to the dump
file, and does not forget about the foreign keys.

You can also display the foreign key constraints for a table like this:

     SHOW TABLE STATUS FROM DB_NAME LIKE 'TBL_NAME';

The foreign key constraints are listed in the `Comment' column of the
output.

When performing foreign key checks, `InnoDB' sets shared row-level
locks on child or parent records it has to look at. `InnoDB' checks
foreign key constraints immediately; the check is not deferred to
transaction commit.

To make it easier to reload dump files for tables that have foreign key
relationships, `mysqldump' automatically includes a statement in the
dump output to set `FOREIGN_KEY_CHECKS' to 0. This avoids problems with
tables having to be reloaded in a particular order when the dump is
reloaded. It is also possible to set this variable manually:

     mysql> SET FOREIGN_KEY_CHECKS = 0;
     mysql> SOURCE DUMP_FILE_NAME;
     mysql> SET FOREIGN_KEY_CHECKS = 1;

This allows you to import the tables in any order if the dump file
contains tables that are not correctly ordered for foreign keys. It
also speeds up the import operation. Setting `FOREIGN_KEY_CHECKS' to 0
can also be useful for ignoring foreign key constraints during `LOAD
DATA' and `ALTER TABLE' operations.  However, even if
`FOREIGN_KEY_CHECKS=0', InnoDB does not allow the creation of a foreign
key constraint where a column references a non-matching column type.
Also, if an `InnoDB' table has foreign key constraints, `ALTER TABLE'
cannot be used to change the table to use another storage engine. To
alter the storage engine, you must drop any foreign key constraints
first.

`InnoDB' does not allow you to drop a table that is referenced by a
`FOREIGN KEY' constraint, unless you do `SET FOREIGN_KEY_CHECKS=0'.
When you drop a table, the constraints that were defined in its create
statement are also dropped.

If you re-create a table that was dropped, it must have a definition
that conforms to the foreign key constraints referencing it. It must
have the right column names and types, and it must have indexes on the
referenced keys, as stated earlier. If these are not satisfied, MySQL
returns error number 1005 and refers to errno 150 in the error message.


File: manual.info,  Node: innodb-and-mysql-replication,  Prev: innodb-foreign-key-constraints,  Up: using-innodb-tables

13.5.6.7 `InnoDB' and MySQL Replication
.......................................

MySQL replication works for `InnoDB' tables as it does for `MyISAM'
tables. It is also possible to use replication in a way where the
storage engine on the slave is not the same as the original storage
engine on the master. For example, you can replicate modifications to an
`InnoDB' table on the master to a `MyISAM' table on the slave.

To set up a new slave for a master, you have to make a copy of the
`InnoDB' tablespace and the log files, as well as the `.frm' files of
the `InnoDB' tables, and move the copies to the slave. If the
`innodb_file_per_table' variable is enabled, you must also copy the
`.ibd' files as well. For the proper procedure to do this, see *Note
innodb-backup::.

If you can shut down the master or an existing slave, you can take a
cold backup of the `InnoDB' tablespace and log files and use that to
set up a slave. To make a new slave without taking down any server you
can also use the commercial `InnoDB' Hot Backup tool
(http://www.innodb.com/hot-backup).

You cannot set up replication for `InnoDB' using the `LOAD TABLE FROM
MASTER' statement, which works only for `MyISAM' tables. There are two
possible workarounds:

   * Dump the table on the master and import the dump file into the
     slave.

   * Use `ALTER TABLE TBL_NAME ENGINE=MyISAM' on the master before
     setting up replication with `LOAD TABLE TBL_NAME FROM MASTER', and
     then use `ALTER TABLE' to convert the master table back to
     `InnoDB' afterward.  However, this should not be done for tables
     that have foreign key definitions because the definitions will be
     lost.

Transactions that fail on the master do not affect replication at all.
MySQL replication is based on the binary log where MySQL writes SQL
statements that modify data. A transaction that fails (for example,
because of a foreign key violation, or because it is rolled back) is
not written to the binary log, so it is not sent to slaves. See *Note
commit::.

Replication and `CASCADE'

Cascading actions for `InnoDB' tables on the master are replicated to
the slave _only_ if both the master's and slave' versions of the tables
sharing the foreign key relation use `InnoDB'. This is true whether you
are using statement-based or row-based replication. For example, suppose
you have started replication, and then create two tables on the master
using the following `CREATE TABLE' statements:

     CREATE TABLE fc1 (
         i INT PRIMARY KEY,
         j INT
     ) ENGINE = InnoDB;

     CREATE TABLE fc2 (
         m INT PRIMARY KEY,
         n INT,
         FOREIGN KEY ni (n) REFERENCES fc1 (i)
             ON DELETE CASCADE
     ) ENGINE = InnoDB;

Suppose that the slave does not have `InnoDB' support enabled. If this
is the case, then the tables on the slave are created, but they use the
`MyISAM' storage engine, and the `FOREIGN KEY' option is ignored. Now
we insert some rows into the tables on the master:

     master> INSERT INTO fc1 VALUES (1, 1), (2, 2);
     Query OK, 2 rows affected (0.09 sec)
     Records: 2  Duplicates: 0  Warnings: 0

     master> INSERT INTO fc2 VALUES (1, 1), (2, 2), (3, 1);
     Query OK, 3 rows affected (0.19 sec)
     Records: 3  Duplicates: 0  Warnings: 0

At this point, on both the master and the slave, table `fc1' contains 2
rows, and table `fc2' contains 3 rows, as shown here:

     master> SELECT * FROM fc1;
     +---+------+
     | i | j    |
     +---+------+
     | 1 |    1 |
     | 2 |    2 |
     +---+------+
     2 rows in set (0.00 sec)

     master> SELECT * FROM fc2;
     +---+------+
     | m | n    |
     +---+------+
     | 1 |    1 |
     | 2 |    2 |
     | 3 |    1 |
     +---+------+
     3 rows in set (0.00 sec)

     slave> SELECT * FROM fc1;
     +---+------+
     | i | j    |
     +---+------+
     | 1 |    1 |
     | 2 |    2 |
     +---+------+
     2 rows in set (0.00 sec)

     slave> SELECT * FROM fc2;
     +---+------+
     | m | n    |
     +---+------+
     | 1 |    1 |
     | 2 |    2 |
     | 3 |    1 |
     +---+------+
     3 rows in set (0.00 sec)

Now suppose that you perform the following `DELETE' statement on the
master:

     master> DELETE FROM fc1 WHERE i=1;
     Query OK, 1 row affected (0.09 sec)

Due to the cascade, table `fc2' on the master now contains only 1 row:

     master> SELECT * FROM fc2;
     +---+---+
     | m | n |
     +---+---+
     | 2 | 2 |
     +---+---+
     1 row in set (0.00 sec)

However, the cascade does not propagate to the slave. The slave's copy
of `fc2' still contains all of the rows that were originally inserted:

     slave> SELECT * FROM fc2;
     +---+---+
     | m | n |
     +---+---+
     | 1 | 1 |
     | 3 | 1 |
     | 2 | 2 |
     +---+---+
     3 rows in set (0.00 sec)

This difference is due to the fact that the cascading deletes are
handled internally by the `InnoDB' storage engine, which means that
none of the changes are logged.


File: manual.info,  Node: adding-and-removing,  Next: innodb-backup,  Prev: using-innodb-tables,  Up: innodb

13.5.7 Adding and Removing `InnoDB' Data and Log Files
------------------------------------------------------

This section describes what you can do when your `InnoDB' tablespace
runs out of room or when you want to change the size of the log files.

The easiest way to increase the size of the `InnoDB' tablespace is to
configure it from the beginning to be auto-extending. Specify the
`autoextend' attribute for the last data file in the tablespace
definition. Then `InnoDB' increases the size of that file automatically
in 8MB increments when it runs out of space. The increment size can be
changed by setting the value of the `innodb_autoextend_increment'
system variable, which is measured in MB.

Alternatively, you can increase the size of your tablespace by adding
another data file. To do this, you have to shut down the MySQL server,
change the tablespace configuration to add a new data file to the end
of `innodb_data_file_path', and start the server again.

If your last data file was defined with the keyword `autoextend', the
procedure for reconfiguring the tablespace must take into account the
size to which the last data file has grown. Obtain the size of the data
file, round it down to the closest multiple of 1024 x 1024 bytes (=
1MB), and specify the rounded size explicitly in
`innodb_data_file_path'. Then you can add another data file. Remember
that only the last data file in the `innodb_data_file_path' can be
specified as auto-extending.

As an example, assume that the tablespace has just one auto-extending
data file `ibdata1':

     innodb_data_home_dir =
     innodb_data_file_path = /ibdata/ibdata1:10M:autoextend

Suppose that this data file, over time, has grown to 988MB. Here is the
configuration line after modifying the original data file to not be
auto-extending and adding another auto-extending data file:

     innodb_data_home_dir =
     innodb_data_file_path = /ibdata/ibdata1:988M;/disk2/ibdata2:50M:autoextend

When you add a new file to the tablespace configuration, make sure that
it does not exist. `InnoDB' will create and initialize the file when
you restart the server.

Currently, you cannot remove a data file from the tablespace. To
decrease the size of your tablespace, use this procedure:

  1. Use `mysqldump' to dump all your `InnoDB' tables.

  2. Stop the server.

  3. Remove all the existing tablespace files, including the `ibdata'
     and `ib_log' files. If you want to keep a backup copy of the
     information, then copy all the `ib*' files to another location
     before the removing the files in your MySQL installation.

  4. Remove any `.frm' files for `InnoDB' tables.

  5. Configure a new tablespace.

  6. Restart the server.

  7. Import the dump files.

If you want to change the number or the size of your `InnoDB' log
files, use the following instructions. The procedure to use depends on
the value of `innodb_fast_shutdown':

   * If `innodb_fast_shutdown' is not set to 2: You must stop the MySQL
     server and make sure that it shuts down without errors (to ensure
     that there is no information for outstanding transactions in the
     logs). Then copy the old log files into a safe place just in case
     something went wrong in the shutdown and you need them to recover
     the tablespace.  Delete the old log files from the log file
     directory, edit `my.cnf' to change the log file configuration, and
     start the MySQL server again.  `mysqld' sees that no log files
     exist at startup and tells you that it is creating new ones.

   * If `innodb_fast_shutdown' is set to 2: You should shut down the
     server, set `innodb_fast_shutdown' to 1, and restart the server.
     The server should be allowed to recover. Then you should shut down
     the server again and follow the procedure described in the
     preceding item to change `InnoDB' log file size. Set
     `innodb_fast_shutdown' back to 2 and restart the server.


File: manual.info,  Node: innodb-backup,  Next: moving,  Prev: adding-and-removing,  Up: innodb

13.5.8 Backing Up and Recovering an `InnoDB' Database
-----------------------------------------------------

* Menu:

* forcing-recovery::             Forcing `InnoDB' Recovery
* innodb-checkpoints::           Checkpoints

The key to safe database management is making regular backups.

`InnoDB Hot Backup' is an online backup tool you can use to backup your
`InnoDB' database while it is running. `InnoDB Hot Backup' does not
require you to shut down your database and it does not set any locks or
disturb your normal database processing. `InnoDB Hot Backup' is a
non-free (commercial) add-on tool with an annual license fee of €390
per computer on which the MySQL server is run. See the `InnoDB Hot
Backup' home page (http://www.innodb.com/hot-backup) for detailed
information and screenshots.

If you are able to shut down your MySQL server, you can make a binary
backup that consists of all files used by `InnoDB' to manage its
tables. Use the following procedure:

  1. Shut down your MySQL server and make sure that it shuts down
     without errors.

  2. Copy all your data files (`ibdata' files and `.ibd' files) into a
     safe place.

  3. Copy all your `ib_logfile' files to a safe place.

  4. Copy your `my.cnf' configuration file or files to a safe place.

  5. Copy all the `.frm' files for your `InnoDB' tables to a safe place.

Replication works with `InnoDB' tables, so you can use MySQL
replication capabilities to keep a copy of your database at database
sites requiring high availability.

In addition to making binary backups as just described, you should also
regularly make dumps of your tables with `mysqldump'. The reason for
this is that a binary file might be corrupted without you noticing it.
Dumped tables are stored into text files that are human-readable, so
spotting table corruption becomes easier. Also, because the format is
simpler, the chance for serious data corruption is smaller.
`mysqldump' also has a `--single-transaction' option that you can use to
make a consistent snapshot without locking out other clients.

To be able to recover your `InnoDB' database to the present from the
binary backup just described, you have to run your MySQL server with
binary logging turned on. Then you can apply the binary log to the
backup database to achieve point-in-time recovery:

     mysqlbinlog YOURHOSTNAME-bin.123 | mysql

To recover from a crash of your MySQL server, the only requirement is
to restart it. `InnoDB' automatically checks the logs and performs a
roll-forward of the database to the present. `InnoDB' automatically
rolls back uncommitted transactions that were present at the time of the
crash. During recovery, `mysqld' displays output something like this:

     InnoDB: Database was not shut down normally.
     InnoDB: Starting recovery from log files...
     InnoDB: Starting log scan based on checkpoint at
     InnoDB: log sequence number 0 13674004
     InnoDB: Doing recovery: scanned up to log sequence number 0 13739520
     InnoDB: Doing recovery: scanned up to log sequence number 0 13805056
     InnoDB: Doing recovery: scanned up to log sequence number 0 13870592
     InnoDB: Doing recovery: scanned up to log sequence number 0 13936128
     ...
     InnoDB: Doing recovery: scanned up to log sequence number 0 20555264
     InnoDB: Doing recovery: scanned up to log sequence number 0 20620800
     InnoDB: Doing recovery: scanned up to log sequence number 0 20664692
     InnoDB: 1 uncommitted transaction(s) which must be rolled back
     InnoDB: Starting rollback of uncommitted transactions
     InnoDB: Rolling back trx no 16745
     InnoDB: Rolling back of trx no 16745 completed
     InnoDB: Rollback of uncommitted transactions completed
     InnoDB: Starting an apply batch of log records to the database...
     InnoDB: Apply batch completed
     InnoDB: Started
     mysqld: ready for connections

If your database gets corrupted or your disk fails, you have to do the
recovery from a backup. In the case of corruption, you should first
find a backup that is not corrupted. After restoring the base backup,
do the recovery from the binary log files using `mysqlbinlog' and
`mysql' to restore the changes performed after the backup was made.

In some cases of database corruption it is enough just to dump, drop,
and re-create one or a few corrupt tables. You can use the `CHECK
TABLE' SQL statement to check whether a table is corrupt, although
`CHECK TABLE' naturally cannot detect every possible kind of
corruption. You can use `innodb_tablespace_monitor' to check the
integrity of the file space management inside the tablespace files.

In some cases, apparent database page corruption is actually due to the
operating system corrupting its own file cache, and the data on disk
may be okay. It is best first to try restarting your computer. Doing so
may eliminate errors that appeared to be database page corruption.


File: manual.info,  Node: forcing-recovery,  Next: innodb-checkpoints,  Prev: innodb-backup,  Up: innodb-backup

13.5.8.1 Forcing `InnoDB' Recovery
..................................

If there is database page corruption, you may want to dump your tables
from the database with `SELECT INTO OUTFILE'. Usually, most of the data
obtained in this way is intact. Even so, the corruption may cause
`SELECT * FROM TBL_NAME' statements or `InnoDB' background operations
to crash or assert, or even to cause `InnoDB' roll-forward recovery to
crash. However, you can force the `InnoDB' storage engine to start up
while preventing background operations from running, so that you are
able to dump your tables. For example, you can add the following line
to the `[mysqld]' section of your option file before restarting the
server:

     [mysqld]
     innodb_force_recovery = 4

The allowable non-zero values for `innodb_force_recovery' follow. A
larger number includes all precautions of smaller numbers. If you are
able to dump your tables with an option value of at most 4, then you are
relatively safe that only some data on corrupt individual pages is
lost. A value of 6 is more drastic because database pages are left in
an obsolete state, which in turn may introduce more corruption into
B-trees and other database structures.

   * `1' (`SRV_FORCE_IGNORE_CORRUPT')

     Let the server run even if it detects a corrupt page. Try to make
     `SELECT * FROM TBL_NAME' jump over corrupt index records and
     pages, which helps in dumping tables.

   * `2' (`SRV_FORCE_NO_BACKGROUND')

     Prevent the main thread from running. If a crash would occur
     during the purge operation, this recovery value prevents it.

   * `3' (`SRV_FORCE_NO_TRX_UNDO')

     Do not run transaction rollbacks after recovery.

   * `4' (`SRV_FORCE_NO_IBUF_MERGE')

     Prevent also insert buffer merge operations. If they would cause a
     crash, do not do them. Do not calculate table statistics.

   * `5' (`SRV_FORCE_NO_UNDO_LOG_SCAN')

     Do not look at undo logs when starting the database: `InnoDB'
     treats even incomplete transactions as committed.

   * `6' (`SRV_FORCE_NO_LOG_REDO')

     Do not do the log roll-forward in connection with recovery.

You can `SELECT' from tables to dump them, or `DROP' or `CREATE' tables
even if forced recovery is used. If you know that a given table is
causing a crash on rollback, you can drop it. You can also use this to
stop a runaway rollback caused by a failing mass import or `ALTER
TABLE'. You can kill the `mysqld' process and set
`innodb_force_recovery' to `3' to bring the database up without the
rollback, then `DROP' the table that is causing the runaway rollback.

_The database must not otherwise be used with any non-zero value of
`innodb_force_recovery'_. As a safety measure, `InnoDB' prevents users
from performing `INSERT', `UPDATE', or `DELETE' operations when
`innodb_force_recovery' is greater than 0.


File: manual.info,  Node: innodb-checkpoints,  Prev: forcing-recovery,  Up: innodb-backup

13.5.8.2 Checkpoints
....................

`InnoDB' implements a checkpoint mechanism known as `fuzzy'
checkpointing.  `InnoDB' flushes modified database pages from the
buffer pool in small batches. There is no need to flush the buffer pool
in one single batch, which would in practice stop processing of user
SQL statements during the checkpointing process.

During crash recovery, `InnoDB' looks for a checkpoint label written to
the log files. It knows that all modifications to the database before
the label are present in the disk image of the database. Then `InnoDB'
scans the log files forward from the checkpoint, applying the logged
modifications to the database.

`InnoDB' writes to its log files on a rotating basis. All committed
modifications that make the database pages in the buffer pool different
from the images on disk must be available in the log files in case
`InnoDB' has to do a recovery. This means that when `InnoDB' starts to
reuse a log file, it has to make sure that the database page images on
disk contain the modifications logged in the log file that `InnoDB' is
going to reuse.  In other words, `InnoDB' must create a checkpoint and
this often involves flushing of modified database pages to disk.

The preceding description explains why making your log files very large
may save disk I/O in checkpointing. It often makes sense to set the
total size of the log files as big as the buffer pool or even bigger.
The drawback of using large log files is that crash recovery can take
longer because there is more logged information to apply to the
database.


File: manual.info,  Node: moving,  Next: innodb-transaction-model,  Prev: innodb-backup,  Up: innodb

13.5.9 Moving an `InnoDB' Database to Another Machine
-----------------------------------------------------

On Windows, `InnoDB' always stores database and table names internally
in lowercase. To move databases in a binary format from Unix to Windows
or from Windows to Unix, you should have all table and database names
in lowercase. A convenient way to accomplish this is to add the
following line to the `[mysqld]' section of your `my.cnf' or `my.ini'
file before creating any databases or tables:

     [mysqld]
     lower_case_table_names=1

Like `MyISAM' data files, `InnoDB' data and log files are
binary-compatible on all platforms having the same floating-point
number format. You can move an `InnoDB' database simply by copying all
the relevant files listed in *Note innodb-backup::.  If the
floating-point formats differ but you have not used `FLOAT' or `DOUBLE'
data types in your tables, then the procedure is the same: simply copy
the relevant files. If the formats differ and your tables contain
floating-point data, you must use `mysqldump' to dump your tables on
one machine and then import the dump files on the other machine.

One way to increase performance is to switch off autocommit mode when
importing data, assuming that the tablespace has enough space for the
big rollback segment that the import transactions generate. Do the
commit only after importing a whole table or a segment of a table.


File: manual.info,  Node: innodb-transaction-model,  Next: innodb-tuning,  Prev: moving,  Up: innodb

13.5.10 `InnoDB' Transaction Model and Locking
----------------------------------------------

* Menu:

* innodb-lock-modes::            `InnoDB' Lock Modes
* innodb-and-autocommit::        `InnoDB' and `AUTOCOMMIT'
* innodb-transaction-isolation::  `InnoDB' and `TRANSACTION ISOLATION LEVEL'
* innodb-consistent-read::       Consistent Non-Locking Read
* innodb-locking-reads::         `SELECT ... FOR UPDATE' and `SELECT ... LOCK IN SHARE MODE' Locking Reads
* innodb-next-key-locking::      Next-Key Locking: Avoiding the Phantom Problem
* innodb-consistent-read-example::  An Example of Consistent Read in `InnoDB'
* innodb-locks-set::             Locks Set by Different SQL Statements in `InnoDB'
* innodb-implicit-commit::       Implicit Transaction Commit and Rollback
* innodb-deadlock-detection::    Deadlock Detection and Rollback
* innodb-deadlocks::             How to Cope with Deadlocks

In the `InnoDB' transaction model, the goal is to combine the best
properties of a multi-versioning database with traditional two-phase
locking. `InnoDB' does locking on the row level and runs queries as
non-locking consistent reads by default, in the style of Oracle. The
lock table in `InnoDB' is stored so space-efficiently that lock
escalation is not needed: Typically several users are allowed to lock
every row in the database, or any random subset of the rows, without
`InnoDB' running out of memory.


File: manual.info,  Node: innodb-lock-modes,  Next: innodb-and-autocommit,  Prev: innodb-transaction-model,  Up: innodb-transaction-model

13.5.10.1 `InnoDB' Lock Modes
.............................

`InnoDB' implements standard row-level locking where there are two
types of locks:

   * A shared (S) lock allows a transaction to read a row (tuple).

   * An exclusive (X) lock allows a transaction to update or delete a
     row.

If transaction `T1' holds a shared (S) lock on tuple `t', then

   * A request from some distinct transaction `T2' for an S lock on `t'
     can be granted immediately. As a result, both `T1' and `T2' hold
     an S lock on `t'.

   * A request from some distinct transaction `T2' for an X lock on `t'
     cannot be granted immediately.

If a transaction `T1' holds an exclusive (X) lock on tuple `t', then a
request from some distinct transaction `T2' for a lock of either type on
`t' cannot be granted immediately. Instead, transaction `T2' has to
wait for transaction `T1' to release its lock on tuple `t'.

Additionally, `InnoDB' supports _multiple granularity locking_ which
allows coexistence of record locks and locks on entire tables. To make
locking at multiple granularity levels practical, additional types of
locks called _intention locks_ are used. Intention locks are table
locks in `InnoDB'. The idea behind intention locks is for a transaction
to indicate which type of lock (shared or exclusive) it will require
later for a row in that table. There are two types of intention locks
used in `InnoDB' (assume that transaction `T' has requested a lock of
the indicated type on table `R'):

   * Intention shared (IS): Transaction `T' intends to set S locks on
     individual rows in table `R'.

   * Intention exclusive (IX): Transaction `T' intends to set X locks
     on those rows.

The intention locking protocol is as follows:

   * Before a given transaction can acquire an S lock on a given row,
     it must first acquire an IS or stronger lock on the table
     containing that row.

   * Before a given transaction can acquire an X lock on a given row,
     it must first acquire an IX lock on the table containing that row.

These rules can be conveniently summarized by means of a _lock type
compatibility matrix_:

               X              IX             S              IS
X              Conflict       Conflict       Conflict       Conflict
IX             Conflict       Compatible     Conflict       Compatible
S              Conflict       Conflict       Compatible     Compatible
IS             Conflict       Compatible     Compatible     Compatible

A lock is granted to a requesting transaction if it is compatible with
existing locks. A lock is not granted to a requesting transaction if it
conflicts with existing locks. A transaction waits until the
conflicting existing lock is released. If a lock request conflicts with
an existing lock and cannot be granted because it would cause deadlock,
an error occurs.

Thus, intention locks do not block anything except full table requests
(for example, `LOCK TABLES ...  WRITE'). The main purpose of IX and IS
locks is to show that someone is locking a row, or going to lock a row
in the table.

The following example illustrates how an error can occur when a lock
request would cause a deadlock. The example involves two clients, A and
B.

First, client A creates a table containing one row, and then begins a
transaction. Within the transaction, A obtains an S lock on the row by
selecting it in share mode:

     mysql> CREATE TABLE t (i INT) ENGINE = InnoDB;
     Query OK, 0 rows affected (1.07 sec)

     mysql> INSERT INTO t (i) VALUES(1);
     Query OK, 1 row affected (0.09 sec)

     mysql> START TRANSACTION;
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT * FROM t WHERE i = 1 LOCK IN SHARE MODE;
     +------+
     | i    |
     +------+
     |    1 |
     +------+
     1 row in set (0.10 sec)

Next, client B begins a transaction and attempts to delete the row from
the table:

     mysql> START TRANSACTION;
     Query OK, 0 rows affected (0.00 sec)

     mysql> DELETE FROM t WHERE i = 1;

The delete operation requires an X lock. The lock cannot be granted
because it is incompatible with the S lock that client A holds, so the
request goes on the queue of lock requests for the row and client B
blocks.

Finally, client A also attempts to delete the row from the table:

     mysql> DELETE FROM t WHERE i = 1;
     ERROR 1213 (40001): Deadlock found when trying to get lock;
     try restarting transaction

Deadlock occurs here because client A needs an X lock to delete the
row. However, that lock request cannot be granted because client B
already has a request for an X lock and is waiting for client A to
release its S lock. Nor can the S lock held by A be upgraded to an X
lock because of the prior request by B for an X lock. As a result,
`InnoDB' generates an error for client A and releases its locks. At
that point, the lock request for client B can be granted and B deletes
the row from the table.


File: manual.info,  Node: innodb-and-autocommit,  Next: innodb-transaction-isolation,  Prev: innodb-lock-modes,  Up: innodb-transaction-model

13.5.10.2 `InnoDB' and `AUTOCOMMIT'
...................................

In `InnoDB', all user activity occurs inside a transaction. If the
autocommit mode is enabled, each SQL statement forms a single
transaction on its own. By default, MySQL starts new connections with
autocommit enabled.

If the autocommit mode is switched off with `SET AUTOCOMMIT = 0', then
we can consider that a user always has a transaction open. An SQL
`COMMIT' or `ROLLBACK' statement ends the current transaction and a new
one starts. A `COMMIT' means that the changes made in the current
transaction are made permanent and become visible to other users. A
`ROLLBACK' statement, on the other hand, cancels all modifications made
by the current transaction. Both statements release all `InnoDB' locks
that were set during the current transaction.

If the connection has autocommit enabled, the user can still perform a
multiple-statement transaction by starting it with an explicit `START
TRANSACTION' or `BEGIN' statement and ending it with `COMMIT' or
`ROLLBACK'.


File: manual.info,  Node: innodb-transaction-isolation,  Next: innodb-consistent-read,  Prev: innodb-and-autocommit,  Up: innodb-transaction-model

13.5.10.3 `InnoDB' and `TRANSACTION ISOLATION LEVEL'
....................................................

In terms of the SQL:1992 transaction isolation levels, the `InnoDB'
default is `REPEATABLE READ'. `InnoDB' offers all four transaction
isolation levels described by the SQL standard. You can set the default
isolation level for all connections by using the
`--transaction-isolation' option on the command line or in an option
file. For example, you can set the option in the `[mysqld]' section of
an option file like this:

     [mysqld]
     transaction-isolation = {READ-UNCOMMITTED | READ-COMMITTED
                              | REPEATABLE-READ | SERIALIZABLE}

A user can change the isolation level for a single session or for all
new incoming connections with the `SET TRANSACTION' statement. Its
syntax is as follows:

     SET [SESSION | GLOBAL] TRANSACTION ISOLATION LEVEL
                            {READ UNCOMMITTED | READ COMMITTED
                             | REPEATABLE READ | SERIALIZABLE}

Note that there are hyphens in the level names for the
`--transaction-isolation' option, but not for the `SET TRANSACTION'
statement.

The default behavior is to set the isolation level for the next (not
started) transaction. If you use the `GLOBAL' keyword, the statement
sets the default transaction level globally for all new connections
created from that point on (but not for existing connections).  You
need the `SUPER' privilege to do this.  Using the `SESSION' keyword
sets the default transaction level for all future transactions
performed on the current connection.

Any client is free to change the session isolation level (even in the
middle of a transaction), or the isolation level for the next
transaction.

You can determine the global and session transaction isolation levels
by checking the value of the `tx_isolation' system variable with these
statements:

     SELECT @@global.tx_isolation;
     SELECT @@tx_isolation;

In row-level locking, `InnoDB' uses next-key locking. That means that
besides index records, `InnoDB' can also lock the `gap' preceding an
index record to block insertions by other users immediately before the
index record. A next-key lock refers to a lock that locks an index
record and the gap before it. A gap lock refers to a lock that only
locks a gap before some index record. Next-key locking for searches or
index scans can be disabled by enabling the
`innodb_locks_unsafe_for_binlog' system variable.

For a detailed description of isolation levels, see *Note
set-transaction::.

In MySQL 5.1, if the `READ COMMITTED' isolation level is used or the
`innodb_locks_unsafe_for_binlog' system variable is enabled, there is
no `InnoDB' gap locking except in constraint checking. Also, record
locks for non-matching rows are released after MySQL has evaluated the
`WHERE' condition.


File: manual.info,  Node: innodb-consistent-read,  Next: innodb-locking-reads,  Prev: innodb-transaction-isolation,  Up: innodb-transaction-model

13.5.10.4 Consistent Non-Locking Read
.....................................

A consistent read means that `InnoDB' uses multi-versioning to present
to a query a snapshot of the database at a point in time. The query
sees the changes made by those transactions that committed before that
point of time, and no changes made by later or uncommitted
transactions. The exception to this rule is that the query sees the
changes made by earlier statements within the same transaction. Note
that the exception to the rule causes the following anomaly: if you
update some rows in a table, a `SELECT' will see the latest version of
the updated rows, but it might also see older versions of any rows. If
other users simultaneously update the same table, the anomaly means
that you may see the table in a state that never existed in the
database.

If you are running with the default `REPEATABLE READ' isolation level,
all consistent reads within the same transaction read the snapshot
established by the first such read in that transaction. You can get a
fresher snapshot for your queries by committing the current transaction
and after that issuing new queries.

Consistent read is the default mode in which `InnoDB' processes `SELECT'
statements in `READ COMMITTED' and `REPEATABLE READ' isolation levels. A
consistent read does not set any locks on the tables it accesses, and
therefore other users are free to modify those tables at the same time
a consistent read is being performed on the table.

Note that consistent read does not work over `DROP TABLE' and over
`ALTER TABLE'.  Consistent read does not work over `DROP TABLE' because
MySQL can't use a table that has been dropped and `InnoDB' destroys the
table. Consistent read does not work over `ALTER TABLE' because `ALTER
TABLE' works by making a temporary copy of the original table and
deleting the original table when the temporary copy is built. When you
reissue a consistent read within a transaction, rows in the new table
are not visible because those rows did not exist when the transaction's
snapshot was taken.

`InnoDB' uses a consistent read for select in clauses like `INSERT INTO
... SELECT' and `UPDATE ... (SELECT)' that do not specify `FOR UPDATE'
or `IN SHARE MODE' if the `innodb_locks_unsafe_for_binlog' option is set
and the isolation level of the transaction is not set to serializable.
Thus no locks are set to rows read from selected table. Otherwise,
`InnoDB' uses stronger locks and the `SELECT' part acts like `READ
COMMITTED', where each consistent read, even within the same
transaction, sets and reads its own fresh snapshot.


File: manual.info,  Node: innodb-locking-reads,  Next: innodb-next-key-locking,  Prev: innodb-consistent-read,  Up: innodb-transaction-model

13.5.10.5 `SELECT ... FOR UPDATE' and `SELECT ... LOCK IN SHARE MODE' Locking Reads
...................................................................................

In some circumstances, a consistent read is not convenient. For
example, you might want to add a new row into your table `child', and
make sure that the child has a parent in table `parent'. The following
example shows how to implement referential integrity in your application
code.

Suppose that you use a consistent read to read the table `parent' and
indeed see the parent of the child in the table. Can you safely add the
child row to table `child'? No, because it may happen that meanwhile
some other user deletes the parent row from the table `parent' without
you being aware of it.

The solution is to perform the `SELECT' in a locking mode using `LOCK
IN SHARE MODE':

     SELECT * FROM parent WHERE NAME = 'Jones' LOCK IN SHARE MODE;

Performing a read in share mode means that we read the latest available
data, and set a shared mode lock on the rows we read.  A shared mode
lock prevents others from updating or deleting the row we have read.
Also, if the latest data belongs to a yet uncommitted transaction of
another client connection, we wait until that transaction commits.
After we see that the preceding query returns the parent `'Jones'', we
can safely add the child record to the `child' table and commit our
transaction.

Let us look at another example: We have an integer counter field in a
table `child_codes' that we use to assign a unique identifier to each
child added to table `child'. Obviously, using a consistent read or a
shared mode read to read the present value of the counter is not a good
idea because two users of the database may then see the same value for
the counter, and a duplicate-key error occurs if two users attempt to
add children with the same identifier to the table.

Here, `LOCK IN SHARE MODE' is not a good solution because if two users
read the counter at the same time, at least one of them ends up in
deadlock when attempting to update the counter.

In this case, there are two good ways to implement the reading and
incrementing of the counter: (1) update the counter first by
incrementing it by 1 and only after that read it, or (2) read the
counter first with a lock mode `FOR UPDATE', and increment after that.
The latter approach can be implemented as follows:

     SELECT counter_field FROM child_codes FOR UPDATE;
     UPDATE child_codes SET counter_field = counter_field + 1;

A `SELECT ... FOR UPDATE' reads the latest available data, setting
exclusive locks on each row it reads.  Thus, it sets the same locks a
searched SQL `UPDATE' would set on the rows.

The preceding description is merely an example of how `SELECT ... FOR
UPDATE' works. In MySQL, the specific task of generating a unique
identifier actually can be accomplished using only a single access to
the table:

     UPDATE child_codes SET counter_field = LAST_INSERT_ID(counter_field + 1);
     SELECT LAST_INSERT_ID();

The `SELECT' statement merely retrieves the identifier information
(specific to the current connection). It does not access any table.

Locks set by `IN SHARE MODE' and `FOR UPDATE' reads are released when
the transaction is committed or rolled back.

*Note*:

Locking of rows for update using `SELECT FOR UPDATE' only applies when
autocommit is disabled (either by beginning transaction with `START
TRANSACTION' or by setting `AUTOCOMMIT' to 0. If autocommit is enabled,
the rows matching the specification are not locked.


File: manual.info,  Node: innodb-next-key-locking,  Next: innodb-consistent-read-example,  Prev: innodb-locking-reads,  Up: innodb-transaction-model

13.5.10.6 Next-Key Locking: Avoiding the Phantom Problem
........................................................

In row-level locking, `InnoDB' uses an algorithm called _next-key
locking_.  `InnoDB' performs the row-level locking in such a way that
when it searches or scans an index of a table, it sets shared or
exclusive locks on the index records it encounters. Thus, the row-level
locks are actually index record locks.

The next-key locks that `InnoDB' sets on index records also affect the
`gap' before that index record. If a user has a shared or exclusive
lock on record `R' in an index, another user cannot insert a new index
record immediately before `R' in the index order. (A gap lock refers to
a lock that only locks a gap before some index record.)

This next-key locking of gaps is done to prevent the so-called `phantom
problem.' Suppose that you want to read and lock all children from the
`child' table having an identifier value greater than 100, with the
intention of updating some column in the selected rows later:

     SELECT * FROM child WHERE id > 100 FOR UPDATE;

Suppose that there is an index on the `id' column. The query scans that
index starting from the first record where `id' is bigger than 100. If
the locks set on the index records would not lock out inserts made in
the gaps, a new row might meanwhile be inserted to the table.  If you
execute the same `SELECT' within the same transaction, you would see a
new row in the result set returned by the query. This is contrary to
the isolation principle of transactions: A transaction should be able
to run so that the data it has read does not change during the
transaction. If we regard a set of rows as a data item, the new
`phantom' child would violate this isolation principle.

When `InnoDB' scans an index, it can also lock the gap after the last
record in the index. Just that happens in the previous example: The
locks set by `InnoDB' prevent any insert to the table where `id' would
be bigger than 100.

You can use next-key locking to implement a uniqueness check in your
application: If you read your data in share mode and do not see a
duplicate for a row you are going to insert, then you can safely insert
your row and know that the next-key lock set on the successor of your
row during the read prevents anyone meanwhile inserting a duplicate for
your row. Thus, the next-key locking allows you to `lock' the
non-existence of something in your table.

In MySQL 5.1, if the `READ COMMITTED' isolation level is used or the
`innodb_locks_unsafe_for_binlog' system variable is enabled, there is
no `InnoDB' gap locking except in constraint checking. Also, record
locks for non-matching rows are released after MySQL has evaluated the
`WHERE' condition.


File: manual.info,  Node: innodb-consistent-read-example,  Next: innodb-locks-set,  Prev: innodb-next-key-locking,  Up: innodb-transaction-model

13.5.10.7 An Example of Consistent Read in `InnoDB'
...................................................

Suppose that you are running in the default `REPEATABLE READ' isolation
level. When you issue a consistent read (that is, an ordinary `SELECT'
statement), `InnoDB' gives your transaction a timepoint according to
which your query sees the database. If another transaction deletes a
row and commits after your timepoint was assigned, you do not see the
row as having been deleted. Inserts and updates are treated similarly.

You can advance your timepoint by committing your transaction and then
doing another `SELECT'.

This is called _multi-versioned concurrency control_.

                    User A                 User B

                SET AUTOCOMMIT=0;      SET AUTOCOMMIT=0;
     time
     |          SELECT * FROM t;
     |          empty set
     |                                 INSERT INTO t VALUES (1, 2);
     |
     v          SELECT * FROM t;
                empty set
                                       COMMIT;

                SELECT * FROM t;
                empty set

                COMMIT;

                SELECT * FROM t;
                ---------------------
                |    1    |    2    |
                ---------------------
                1 row in set

In this example, user A sees the row inserted by B only when B has
committed the insert and A has committed as well, so that the timepoint
is advanced past the commit of B.

If you want to see the `freshest' state of the database, you should use
either the `READ COMMITTED' isolation level or a locking read:

     SELECT * FROM t LOCK IN SHARE MODE;


File: manual.info,  Node: innodb-locks-set,  Next: innodb-implicit-commit,  Prev: innodb-consistent-read-example,  Up: innodb-transaction-model

13.5.10.8 Locks Set by Different SQL Statements in `InnoDB'
...........................................................

A locking read, an `UPDATE', or a `DELETE' generally set record locks
on every index record that is scanned in the processing of the SQL
statement. It does not matter if there are `WHERE' conditions in the
statement that would exclude the row. `InnoDB' does not remember the
exact `WHERE' condition, but only knows which index ranges were
scanned. The record locks are normally next-key locks that also block
inserts to the `gap' immediately before the record.

If the locks to be set are exclusive, `InnoDB' always retrieves also
the clustered index record and sets a lock on it.

If you do not have indexes suitable for your statement and MySQL has to
scan the whole table to process the statement, every row of the table
becomes locked, which in turn blocks all inserts by other users to the
table. It is important to create good indexes so that your queries do
not unnecessarily need to scan many rows.

For `SELECT ... FOR UPDATE' or `SELECT ... IN SHARE MODE', locks are
acquired for scanned rows, and expected to be released for rows that do
not qualify for inclusion in the result set (for example, if they do not
meet the criteria given in the `WHERE' clause).  However, in some
cases, rows might not be unlocked immediately because the relationship
between a result row and its original source is lost during query
execution. For example, in a `UNION', scanned (and locked) rows from a
table might be inserted into a temporary table before evaluation
whether they qualify for the result set. In this circumstance, the
relationship of the rows in the temporary table to the rows in the
original table is lost and the latter rows are not unlocked until the
end of query execution.

`InnoDB' sets specific types of locks as follows:

   * `SELECT ... FROM' is a consistent read, reading a snapshot of the
     database and setting no locks unless the transaction isolation
     level is set to `SERIALIZABLE'. For `SERIALIZABLE' level, this
     sets shared next-key locks on the index records it encounters.

   * `SELECT ... FROM ... LOCK IN SHARE MODE' sets shared next-key
     locks on all index records the read encounters.

   * `SELECT ... FROM ... FOR UPDATE' sets exclusive next-key locks on
     all index records the read encounters and also on the
     corresponding clustered index records if a secondary index is used
     in the search.

   * `UPDATE ... WHERE ...' sets an exclusive next-key lock on every
     record the search encounters.

   * `DELETE FROM ... WHERE ...' sets an exclusive next-key lock on
     every record the search encounters.

   * `INSERT INTO ... VALUES (...)' sets an exclusive lock on the
     inserted row. Note that this lock is not a next-key lock and does
     not prevent other users from inserting to the gap before the
     inserted row. If a duplicate-key error occurs, a shared lock on
     the duplicate index record is set.

   * `REPLACE' is done like an `INSERT' if there is no collision on a
     unique key. Otherwise, an exclusive next-key lock is placed on the
     row that has to be updated.

   * While initializing a previously specified `AUTO_INCREMENT' column
     on a table, `InnoDB' sets an exclusive lock on the end of the
     index associated with the `AUTO_INCREMENT' column. In accessing the
     auto-increment counter, `InnoDB' uses a specific table lock mode
     `AUTO-INC' where the lock lasts only to the end of the current SQL
     statement, not to the end of the entire transaction. Note that
     other clients cannot insert into the table while the `AUTO-INC'
     table lock is held; see *Note innodb-and-autocommit::.

     `InnoDB' fetches the value of a previously initialized
     `AUTO_INCREMENT' column without setting any locks.

   * `INSERT INTO T SELECT ... FROM S WHERE ...' sets an exclusive
     (non-next-key) lock on each row inserted into `T'. `InnoDB' sets
     shared next-key locks on `S', unless
     `innodb_locks_unsafe_for_binlog' is enabled, in which case it does
     the search on `S' as a consistent read.  `InnoDB' has to set locks
     in the former case: In roll-forward recovery from a backup, every
     SQL statement has to be executed in exactly the same way it was
     done originally.

   * `CREATE TABLE ... SELECT ...' performs the `SELECT' as a
     consistent read or with shared locks, as in the previous item.

   * If a `FOREIGN KEY' constraint is defined on a table, any insert,
     update, or delete that requires the constraint condition to be
     checked sets shared record-level locks on the records that it
     looks at to check the constraint. `InnoDB' also sets these locks
     in the case where the constraint fails.

   * `LOCK TABLES' sets table locks, but it is the higher MySQL layer
     above the `InnoDB' layer that sets these locks. `InnoDB' is aware
     of table locks if `innodb_table_locks=1' (the default) and
     `AUTOCOMMIT=0', and the MySQL layer above `InnoDB' knows about
     row-level locks.  Otherwise, `InnoDB''s automatic deadlock
     detection cannot detect deadlocks where such table locks are
     involved. Also, because the higher MySQL layer does not know about
     row-level locks, it is possible to get a table lock on a table
     where another user currently has row-level locks.  However, this
     does not endanger transaction integrity, as discussed in *Note
     innodb-deadlock-detection::.  See also *Note innodb-restrictions::.

   * In MySQL 5.1, if the `READ COMMITTED' isolation level is used or
     the `innodb_locks_unsafe_for_binlog' system variable is enabled,
     there is no `InnoDB' gap locking except in constraint checking.
     Also, record locks for non-matching rows are released after MySQL
     has evaluated the `WHERE' condition.


File: manual.info,  Node: innodb-implicit-commit,  Next: innodb-deadlock-detection,  Prev: innodb-locks-set,  Up: innodb-transaction-model

13.5.10.9 Implicit Transaction Commit and Rollback
..................................................

By default, MySQL begins each client connection with autocommit mode
enabled. When autocommit is enabled, MySQL does a commit after each SQL
statement if that statement did not return an error. If an SQL
statement returns an error, the commit or rollback behavior depends on
the error. See *Note innodb-error-handling::.

If you have the autocommit mode off and close a connection without
explicitly committing the final transaction, MySQL rolls back that
transaction.

For details about which statements implicitly end a transaction, as if
you had done a `COMMIT' before executing the statement, see *Note
implicit-commit::.


File: manual.info,  Node: innodb-deadlock-detection,  Next: innodb-deadlocks,  Prev: innodb-implicit-commit,  Up: innodb-transaction-model

13.5.10.10 Deadlock Detection and Rollback
..........................................

`InnoDB' automatically detects a deadlock of transactions and rolls
back a transaction or transactions to break the deadlock. `InnoDB'
tries to pick small transactions to roll back, where the size of a
transaction is determined by the number of rows inserted, updated, or
deleted.

`InnoDB' is aware of table locks if `innodb_table_locks=1' (the
default) and `AUTOCOMMIT=0', and the MySQL layer above it knows about
row-level locks. Otherwise, `InnoDB' cannot detect deadlocks where a
table lock set by a MySQL `LOCK TABLES' statement or a lock set by a
storage engine other than `InnoDB' is involved. You must resolve these
situations by setting the value of the `innodb_lock_wait_timeout'
system variable.

When `InnoDB' performs a complete rollback of a transaction, all locks
set by the transaction are released.  However, if just a single SQL
statement is rolled back as a result of an error, some of the locks set
by the statement may be preserved. This happens because `InnoDB' stores
row locks in a format such that it cannot know afterward which lock was
set by which statement.

As of MySQL 5.1.24, if a `SELECT' calls a stored function in a
transaction, and a statement within the function fails, that statement
rolls back. Furthermore, if `ROLLBACK' is executed after that, the
entire transaction rolls back. Before 5.1.24, the failed statement did
not roll back when it failed (even though it might ultimately get
rolled back by a `ROLLBACK' later that rolls back the entire
transaction).


File: manual.info,  Node: innodb-deadlocks,  Prev: innodb-deadlock-detection,  Up: innodb-transaction-model

13.5.10.11 How to Cope with Deadlocks
.....................................

Deadlocks are a classic problem in transactional databases, but they
are not dangerous unless they are so frequent that you cannot run
certain transactions at all. Normally, you must write your applications
so that they are always prepared to re-issue a transaction if it gets
rolled back because of a deadlock.

`InnoDB' uses automatic row-level locking. You can get deadlocks even
in the case of transactions that just insert or delete a single row.
That is because these operations are not really `atomic'; they
automatically set locks on the (possibly several) index records of the
row inserted or deleted.

You can cope with deadlocks and reduce the likelihood of their
occurrence with the following techniques:

   * Use `SHOW ENGINE INNODB STATUS' to determine the cause of the
     latest deadlock. That can help you to tune your application to
     avoid deadlocks.

   * Always be prepared to re-issue a transaction if it fails due to
     deadlock. Deadlocks are not dangerous. Just try again.

   * Commit your transactions often. Small transactions are less prone
     to collision.

   * If you are using locking reads (`SELECT ... FOR UPDATE' or `...
     LOCK IN SHARE MODE'), try using a lower isolation level such as
     `READ COMMITTED'.

   * Access your tables and rows in a fixed order. Then transactions
     form well-defined queues and do not deadlock.

   * Add well-chosen indexes to your tables. Then your queries need to
     scan fewer index records and consequently set fewer locks. Use
     `EXPLAIN SELECT' to determine which indexes the MySQL server
     regards as the most appropriate for your queries.

   * Use less locking. If you can afford to allow a `SELECT' to return
     data from an old snapshot, do not add the clause `FOR UPDATE' or
     `LOCK IN SHARE MODE' to it. Using the `READ COMMITTED' isolation
     level is good here, because each consistent read within the same
     transaction reads from its own fresh snapshot.

   * If nothing else helps, serialize your transactions with
     table-level locks. The correct way to use `LOCK TABLES' with
     transactional tables, such as `InnoDB' tables, is to set
     `AUTOCOMMIT = 0' and not to call `UNLOCK TABLES' until after you
     commit the transaction explicitly. For example, if you need to
     write to table `t1' and read from table `t2', you can do this:

          SET AUTOCOMMIT=0;
          LOCK TABLES t1 WRITE, t2 READ, ...;
          ... DO SOMETHING WITH TABLES T1 AND T2 HERE ...
          COMMIT;
          UNLOCK TABLES;

     Table-level locks make your transactions queue nicely, and
     deadlocks are avoided.

   * Another way to serialize transactions is to create an auxiliary
     `semaphore' table that contains just a single row. Have each
     transaction update that row before accessing other tables. In that
     way, all transactions happen in a serial fashion. Note that the
     `InnoDB' instant deadlock detection algorithm also works in this
     case, because the serializing lock is a row-level lock. With MySQL
     table-level locks, the timeout method must be used to resolve
     deadlocks.


File: manual.info,  Node: innodb-tuning,  Next: innodb-multi-versioning,  Prev: innodb-transaction-model,  Up: innodb

13.5.11 `InnoDB' Performance Tuning Tips
----------------------------------------

* Menu:

* innodb-monitor::               `SHOW ENGINE INNODB STATUS' and the `InnoDB' Monitors

   * In `InnoDB', having a long `PRIMARY KEY' wastes a lot of disk
     space because its value must be stored with every secondary index
     record. (See *Note innodb-table-and-index::.) Create an
     `AUTO_INCREMENT' column as the primary key if your primary key is
     long.

   * If the Unix `top' tool or the Windows Task Manager shows that the
     CPU usage percentage with your workload is less than 70%, your
     workload is probably disk-bound. Maybe you are making too many
     transaction commits, or the buffer pool is too small. Making the
     buffer pool bigger can help, but do not set it equal to more than
     80% of physical memory.

   * Wrap several modifications into one transaction.  `InnoDB' must
     flush the log to disk at each transaction commit if that
     transaction made modifications to the database. The rotation speed
     of a disk is typically at most 167 revolutions/second, which
     constrains the number of commits to the same 167^th of a second if
     the disk does not `fool' the operating system.

   * If you can afford the loss of some of the latest committed
     transactions if a crash occurs, you can set the
     `innodb_flush_log_at_trx_commit' parameter to 0. `InnoDB' tries to
     flush the log once per second anyway, although the flush is not
     guaranteed. You should also set the value of `innodb_support_xa'
     to 0 which will reduce the number of disk flushes due to
     synchronizing on disk data and the binary log.

   * Make your log files big, even as big as the buffer pool. When
     `InnoDB' has written the log files full, it has to write the
     modified contents of the buffer pool to disk in a checkpoint.
     Small log files cause many unnecessary disk writes. The drawback
     of big log files is that the recovery time is longer.

   * Make the log buffer quite large as well (on the order of 8MB).

   * Use the `VARCHAR' data type instead of `CHAR' if you are storing
     variable-length strings or if the column may contain many `NULL'
     values. A `CHAR(N)' column always takes N characters to store
     data, even if the string is shorter or its value is `NULL'.
     Smaller tables fit better in the buffer pool and reduce disk I/O.

     When using `row_format=compact' (the default `InnoDB' record
     format in MySQL 5.1) and variable-length character sets, such as
     `utf8' or `sjis', `CHAR(N)' will occupy a variable amount of
     space, at least N bytes.

   * In some versions of GNU/Linux and Unix, flushing files to disk
     with the Unix `fsync()' call (which `InnoDB' uses by default) and
     other similar methods is surprisingly slow. If you are
     dissatisfied with database write performance, you might try
     setting the `innodb_flush_method' parameter to `O_DSYNC'. Although
     `O_DSYNC' seems to be slower on most systems, yours might not be
     one of them.

   * When using the `InnoDB' storage engine on Solaris 10 for x86_64
     architecture (AMD Opteron), it is important to mount any
     filesystems used for storing `InnoDB'-related files using the
     `forcedirectio' option. (The default on Solaris 10/x86_64 is _not_
     to use this option.) Failure to use `forcedirectio' causes a
     serious degradation of `InnoDB''s speed and performance on this
     platform.

     When using the `InnoDB' storage engine with a large
     `innodb_buffer_pool_size' value on any release of Solaris 2.6 and
     up and any platform (sparc/x86/x64/amd64), a significant
     performance gain can be achieved by placing `InnoDB' data files and
     log files on raw devices or on a separate direct I/O UFS
     filesystem (using mount option `forcedirectio'; see
     `mount_ufs(1M)'). Users of the Veritas filesystem VxFS should use
     the mount option `convosync=direct'.

     Other MySQL data files, such as those for `MyISAM' tables, should
     not be placed on a direct I/O filesystem. Executables or libraries
     _must not_ be placed on a direct I/O filesystem.

   * When importing data into `InnoDB', make sure that MySQL does not
     have autocommit mode enabled because that requires a log flush to
     disk for every insert. To disable autocommit during your import
     operation, surround it with `SET AUTOCOMMIT' and `COMMIT'
     statements:

          SET AUTOCOMMIT=0;
          ... SQL IMPORT STATEMENTS ...
          COMMIT;

     If you use the `mysqldump' option `--opt', you get dump files that
     are fast to import into an `InnoDB' table, even without wrapping
     them with the `SET AUTOCOMMIT' and `COMMIT' statements.

   * Beware of big rollbacks of mass inserts: `InnoDB' uses the insert
     buffer to save disk I/O in inserts, but no such mechanism is used
     in a corresponding rollback. A disk-bound rollback can take 30
     times as long to perform as the corresponding insert. Killing the
     database process does not help because the rollback starts again
     on server startup. The only way to get rid of a runaway rollback
     is to increase the buffer pool so that the rollback becomes
     CPU-bound and runs fast, or to use a special procedure. See *Note
     forcing-recovery::.

   * Beware also of other big disk-bound operations. Use `DROP TABLE'
     and `CREATE TABLE' to empty a table, not `DELETE FROM TBL_NAME'.

   * Use the multiple-row `INSERT' syntax to reduce communication
     overhead between the client and the server if you need to insert
     many rows:

          INSERT INTO yourtable VALUES (1,2), (5,5), ...;

     This tip is valid for inserts into any table, not just `InnoDB'
     tables.

   * If you have `UNIQUE' constraints on secondary keys, you can speed
     up table imports by temporarily turning off the uniqueness checks
     during the import session:

          SET UNIQUE_CHECKS=0;
          ... IMPORT OPERATION ...
          SET UNIQUE_CHECKS=1;

     For big tables, this saves a lot of disk I/O because `InnoDB' can
     use its insert buffer to write secondary index records in a batch.
     Be certain that the data contains no duplicate keys.
     `UNIQUE_CHECKS' allows but does not require storage engines to
     ignore duplicate keys.

   * If you have `FOREIGN KEY' constraints in your tables, you can
     speed up table imports by turning the foreign key checks off for
     the duration of the import session:

          SET FOREIGN_KEY_CHECKS=0;
          ... IMPORT OPERATION ...
          SET FOREIGN_KEY_CHECKS=1;

     For big tables, this can save a lot of disk I/O.

   * If you often have recurring queries for tables that are not
     updated frequently, use the query cache:

          [mysqld]
          query_cache_type = ON
          query_cache_size = 10M

   * Unlike `MyISAM', `InnoDB' does not store an index cardinality
     value in its tables.  Instead, `InnoDB' computes a cardinality for
     a table the first time it accesses it after startup. With a large
     number of tables, this might take significant time. It is the
     initial table open operation that is important, so to `warm up' a
     table for later use, you might want to use it immediately after
     start up by issuing a statement such as `SELECT 1 FROM TBL_NAME
     LIMIT 1'.

MySQL Enterprise

For optimization recommendations geared to your specific circumstances
subscribe to the MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: innodb-monitor,  Prev: innodb-tuning,  Up: innodb-tuning

13.5.11.1 `SHOW ENGINE INNODB STATUS' and the `InnoDB' Monitors
...............................................................

`InnoDB' includes `InnoDB' Monitors that print information about the
`InnoDB' internal state. You can use the `SHOW ENGINE INNODB STATUS'
SQL statement at any time to fetch the output of the standard `InnoDB'
Monitor to your SQL client. This information is useful in performance
tuning. (If you are using the `mysql' interactive SQL client, the output
is more readable if you replace the usual semicolon statement
terminator with `\G'.) For a discussion of `InnoDB' lock modes, see
*Note innodb-lock-modes::.

     mysql> SHOW ENGINE INNODB STATUS\G

Another way to use `InnoDB' Monitors is to let them periodically write
data to the standard output of the `mysqld' server. In this case, no
output is sent to clients. When switched on, `InnoDB' Monitors print
data about every 15 seconds. Server output usually is directed to the
`.err' log in the MySQL data directory. This data is useful in
performance tuning.  On Windows, you must start the server from a
command prompt in a console window with the `--console' option if you
want to direct the output to the window rather than to the error log.

Monitor output includes the following types of information:

   * Table and record locks held by each active transaction

   * Lock waits of a transactions

   * Semaphore waits of threads

   * Pending file I/O requests

   * Buffer pool statistics

   * Purge and insert buffer merge activity of the main `InnoDB' thread

To cause the standard `InnoDB' Monitor to write to the standard output
of `mysqld', use the following SQL statement:

     CREATE TABLE innodb_monitor (a INT) ENGINE=INNODB;

The monitor can be stopped by issuing the following statement:

     DROP TABLE innodb_monitor;

The `CREATE TABLE' syntax is just a way to pass a command to the
`InnoDB' engine through MySQL's SQL parser: The only things that matter
are the table name `innodb_monitor' and that it be an `InnoDB' table.
The structure of the table is not relevant at all for the `InnoDB'
Monitor.  If you shut down the server, the monitor does not restart
automatically when you restart the server. You must drop the monitor
table and issue a new `CREATE TABLE' statement to start the monitor.
(This syntax may change in a future release.)

You can use `innodb_lock_monitor' in a similar fashion. This is the
same as `innodb_monitor', except that it also provides a great deal of
lock information. A separate `innodb_tablespace_monitor' prints a list
of created file segments existing in the tablespace and validates the
tablespace allocation data structures. In addition, there is
`innodb_table_monitor' with which you can print the contents of the
`InnoDB' internal data dictionary.

As of MySQL 5.1.24, the `PROCESS' privilege is required to start or
stop the `InnoDB' monitor tables.

A sample of `InnoDB' Monitor output:

     mysql> SHOW ENGINE INNODB STATUS\G
     *************************** 1. row ***************************
     Status:
     =====================================
     030709 13:00:59 INNODB MONITOR OUTPUT
     =====================================
     Per second averages calculated from the last 18 seconds
     ----------
     SEMAPHORES
     ----------
     OS WAIT ARRAY INFO: reservation count 413452, signal count 378357
     --Thread 32782 has waited at btr0sea.c line 1477 for 0.00 seconds the
     semaphore: X-lock on RW-latch at 41a28668 created in file btr0sea.c line 135
     a writer (thread id 32782) has reserved it in mode wait exclusive
     number of readers 1, waiters flag 1
     Last time read locked in file btr0sea.c line 731
     Last time write locked in file btr0sea.c line 1347
     Mutex spin waits 0, rounds 0, OS waits 0
     RW-shared spins 108462, OS waits 37964; RW-excl spins 681824, OS waits
     375485
     ------------------------
     LATEST FOREIGN KEY ERROR
     ------------------------
     030709 13:00:59 Transaction:
     TRANSACTION 0 290328284, ACTIVE 0 sec, process no 3195, OS thread id 34831
     inserting
     15 lock struct(s), heap size 2496, undo log entries 9
     MySQL thread id 25, query id 4668733 localhost heikki update
     insert into ibtest11a (D, B, C) values (5, 'khDk' ,'khDk')
     Foreign key constraint fails for table test/ibtest11a:
     ,
       CONSTRAINT `0_219242` FOREIGN KEY (`A`, `D`) REFERENCES `ibtest11b` (`A`,
       `D`) ON DELETE CASCADE ON UPDATE CASCADE
     Trying to add in child table, in index PRIMARY tuple:
      0: len 4; hex 80000101; asc ....;; 1: len 4; hex 80000005; asc ....;; 2:
      len 4; hex 6b68446b; asc khDk;; 3: len 6; hex 0000114e0edc; asc ...N..;; 4:
      len 7; hex 00000000c3e0a7; asc .......;; 5: len 4; hex 6b68446b; asc khDk;;
     But in parent table test/ibtest11b, in index PRIMARY,
     the closest match we can find is record:
     RECORD: info bits 0 0: len 4; hex 8000015b; asc ...[;; 1: len 4; hex
     80000005; asc ....;; 2: len 3; hex 6b6864; asc khd;; 3: len 6; hex
     0000111ef3eb; asc ......;; 4: len 7; hex 800001001e0084; asc .......;; 5:
     len 3; hex 6b6864; asc khd;;
     ------------------------
     LATEST DETECTED DEADLOCK
     ------------------------
     030709 12:59:58
     *** (1) TRANSACTION:
     TRANSACTION 0 290252780, ACTIVE 1 sec, process no 3185, OS thread id 30733
     inserting
     LOCK WAIT 3 lock struct(s), heap size 320, undo log entries 146
     MySQL thread id 21, query id 4553379 localhost heikki update
     INSERT INTO alex1 VALUES(86, 86, 794,'aA35818','bb','c79166','d4766t',
     'e187358f','g84586','h794',date_format('2001-04-03 12:54:22','%Y-%m-%d
     %H:%i'),7
     *** (1) WAITING FOR THIS LOCK TO BE GRANTED:
     RECORD LOCKS space id 0 page no 48310 n bits 568 table test/alex1 index
     symbole trx id 0 290252780 lock mode S waiting
     Record lock, heap no 324 RECORD: info bits 0 0: len 7; hex 61613335383138;
     asc aa35818;; 1:
     *** (2) TRANSACTION:
     TRANSACTION 0 290251546, ACTIVE 2 sec, process no 3190, OS thread id 32782
     inserting
     130 lock struct(s), heap size 11584, undo log entries 437
     MySQL thread id 23, query id 4554396 localhost heikki update
     REPLACE INTO alex1 VALUES(NULL, 32, NULL,'aa3572','','c3572','d6012t','',
     NULL,'h396', NULL, NULL, 7.31,7.31,7.31,200)
     *** (2) HOLDS THE LOCK(S):
     RECORD LOCKS space id 0 page no 48310 n bits 568 table test/alex1 index
     symbole trx id 0 290251546 lock_mode X locks rec but not gap
     Record lock, heap no 324 RECORD: info bits 0 0: len 7; hex 61613335383138;
     asc aa35818;; 1:
     *** (2) WAITING FOR THIS LOCK TO BE GRANTED:
     RECORD LOCKS space id 0 page no 48310 n bits 568 table test/alex1 index
     symbole trx id 0 290251546 lock_mode X locks gap before rec insert intention
     waiting
     Record lock, heap no 82 RECORD: info bits 0 0: len 7; hex 61613335373230;
     asc aa35720;; 1:
     *** WE ROLL BACK TRANSACTION (1)
     ------------
     TRANSACTIONS
     ------------
     Trx id counter 0 290328385
     Purge done for trx's n:o < 0 290315608 undo n:o < 0 17
     Total number of lock structs in row lock hash table 70
     LIST OF TRANSACTIONS FOR EACH SESSION:
     ---TRANSACTION 0 0, not started, process no 3491, OS thread id 42002
     MySQL thread id 32, query id 4668737 localhost heikki
     show innodb status
     ---TRANSACTION 0 290328384, ACTIVE 0 sec, process no 3205, OS thread id
     38929 inserting
     1 lock struct(s), heap size 320
     MySQL thread id 29, query id 4668736 localhost heikki update
     insert into speedc values (1519229,1, 'hgjhjgghggjgjgjgjgjggjgjgjgjgjgggjgjg
     jlhhgghggggghhjhghgggggghjhghghghghghhhhghghghjhhjghjghjkghjghjghjghjfhjfh
     ---TRANSACTION 0 290328383, ACTIVE 0 sec, process no 3180, OS thread id
     28684 committing
     1 lock struct(s), heap size 320, undo log entries 1
     MySQL thread id 19, query id 4668734 localhost heikki update
     insert into speedcm values (1603393,1, 'hgjhjgghggjgjgjgjgjggjgjgjgjgjgggjgj
     gjlhhgghggggghhjhghgggggghjhghghghghghhhhghghghjhhjghjghjkghjghjghjghjfhjf
     ---TRANSACTION 0 290328327, ACTIVE 0 sec, process no 3200, OS thread id
     36880 starting index read
     LOCK WAIT 2 lock struct(s), heap size 320
     MySQL thread id 27, query id 4668644 localhost heikki Searching rows for
     update
     update ibtest11a set B = 'kHdkkkk' where A = 89572
     ------- TRX HAS BEEN WAITING 0 SEC FOR THIS LOCK TO BE GRANTED:
     RECORD LOCKS space id 0 page no 65556 n bits 232 table test/ibtest11a index
     PRIMARY trx id 0 290328327 lock_mode X waiting
     Record lock, heap no 1 RECORD: info bits 0 0: len 9; hex 73757072656d756d00;
     asc supremum.;;
     ------------------
     ---TRANSACTION 0 290328284, ACTIVE 0 sec, process no 3195, OS thread id
     34831 rollback of SQL statement
     ROLLING BACK 14 lock struct(s), heap size 2496, undo log entries 9
     MySQL thread id 25, query id 4668733 localhost heikki update
     insert into ibtest11a (D, B, C) values (5, 'khDk' ,'khDk')
     ---TRANSACTION 0 290327208, ACTIVE 1 sec, process no 3190, OS thread id
     32782
     58 lock struct(s), heap size 5504, undo log entries 159
     MySQL thread id 23, query id 4668732 localhost heikki update
     REPLACE INTO alex1 VALUES(86, 46, 538,'aa95666','bb','c95666','d9486t',
     'e200498f','g86814','h538',date_format('2001-04-03 12:54:22','%Y-%m-%d
     %H:%i'),
     ---TRANSACTION 0 290323325, ACTIVE 3 sec, process no 3185, OS thread id
     30733 inserting
     4 lock struct(s), heap size 1024, undo log entries 165
     MySQL thread id 21, query id 4668735 localhost heikki update
     INSERT INTO alex1 VALUES(NULL, 49, NULL,'aa42837','','c56319','d1719t','',
     NULL,'h321', NULL, NULL, 7.31,7.31,7.31,200)
     --------
     FILE I/O
     --------
     I/O thread 0 state: waiting for i/o request (insert buffer thread)
     I/O thread 1 state: waiting for i/o request (log thread)
     I/O thread 2 state: waiting for i/o request (read thread)
     I/O thread 3 state: waiting for i/o request (write thread)
     Pending normal aio reads: 0, aio writes: 0,
      ibuf aio reads: 0, log i/o's: 0, sync i/o's: 0
     Pending flushes (fsync) log: 0; buffer pool: 0
     151671 OS file reads, 94747 OS file writes, 8750 OS fsyncs
     25.44 reads/s, 18494 avg bytes/read, 17.55 writes/s, 2.33 fsyncs/s
     -------------------------------------
     INSERT BUFFER AND ADAPTIVE HASH INDEX
     -------------------------------------
     Ibuf for space 0: size 1, free list len 19, seg size 21,
     85004 inserts, 85004 merged recs, 26669 merges
     Hash table size 207619, used cells 14461, node heap has 16 buffer(s)
     1877.67 hash searches/s, 5121.10 non-hash searches/s
     ---
     LOG
     ---
     Log sequence number 18 1212842764
     Log flushed up to   18 1212665295
     Last checkpoint at  18 1135877290
     0 pending log writes, 0 pending chkp writes
     4341 log i/o's done, 1.22 log i/o's/second
     ----------------------
     BUFFER POOL AND MEMORY
     ----------------------
     Total memory allocated 84966343; in additional pool allocated 1402624
     Buffer pool size   3200
     Free buffers       110
     Database pages     3074
     Modified db pages  2674
     Pending reads 0
     Pending writes: LRU 0, flush list 0, single page 0
     Pages read 171380, created 51968, written 194688
     28.72 reads/s, 20.72 creates/s, 47.55 writes/s
     Buffer pool hit rate 999 / 1000
     --------------
     ROW OPERATIONS
     --------------
     0 queries inside InnoDB, 0 queries in queue
     Main thread process no. 3004, id 7176, state: purging
     Number of rows inserted 3738558, updated 127415, deleted 33707, read 755779
     1586.13 inserts/s, 50.89 updates/s, 28.44 deletes/s, 107.88 reads/s
     ----------------------------
     END OF INNODB MONITOR OUTPUT
     ============================

Some notes on the output:

   * If the `TRANSACTIONS' section reports lock waits, your
     applications may have lock contention. The output can also help to
     trace the reasons for transaction deadlocks.

   * The `SEMAPHORES' section reports threads waiting for a semaphore
     and statistics on how many times threads have needed a spin or a
     wait on a mutex or a rw-lock semaphore. A large number of threads
     waiting for semaphores may be a result of disk I/O, or contention
     problems inside `InnoDB'. Contention can be due to heavy
     parallelism of queries or problems in operating system thread
     scheduling. Setting `innodb_thread_concurrency' smaller than the
     default value can help in such situations.

   * The `BUFFER POOL AND MEMORY' section gives you statistics on pages
     read and written. You can calculate from these numbers how many
     data file I/O operations your queries currently are doing.

   * The `ROW OPERATIONS' section shows what the main thread is doing.

`InnoDB' sends diagnostic output to `stderr' or to files rather than to
`stdout' or fixed-size memory buffers, to avoid potential buffer
overflows. As a side effect, the output of `SHOW ENGINE INNODB STATUS'
is written to a status file in the MySQL data directory every fifteen
seconds.  The name of the file is `innodb_status.PID', where PID is the
server process ID.  `InnoDB' removes the file for a normal shutdown. If
abnormal shutdowns have occurred, instances of these status files may
be present and must be removed manually.  Before removing them, you
might want to examine them to see whether they contain useful
information about the cause of abnormal shutdowns. The
`innodb_status.PID' file is created only if the configuration option
`innodb_status_file=1' is set.


File: manual.info,  Node: innodb-multi-versioning,  Next: innodb-table-and-index,  Prev: innodb-tuning,  Up: innodb

13.5.12 Implementation of Multi-Versioning
------------------------------------------

Because `InnoDB' is a multi-versioned storage engine, it must keep
information about old versions of rows in the tablespace. This
information is stored in a data structure called a _rollback segment_
(after an analogous data structure in Oracle).

Internally, `InnoDB' adds two fields to each row stored in the
database. A 6-byte field indicates the transaction identifier for the
last transaction that inserted or updated the row. Also, a deletion is
treated internally as an update where a special bit in the row is set
to mark it as deleted. Each row also contains a 7-byte field called the
roll pointer. The roll pointer points to an undo log record written to
the rollback segment. If the row was updated, the undo log record
contains the information necessary to rebuild the content of the row
before it was updated.

`InnoDB' uses the information in the rollback segment to perform the
undo operations needed in a transaction rollback. It also uses the
information to build earlier versions of a row for a consistent read.

Undo logs in the rollback segment are divided into insert and update
undo logs. Insert undo logs are needed only in transaction rollback and
can be discarded as soon as the transaction commits.  Update undo logs
are used also in consistent reads, but they can be discarded only after
there is no transaction present for which `InnoDB' has assigned a
snapshot that in a consistent read could need the information in the
update undo log to build an earlier version of a database row.

You must remember to commit your transactions regularly, including
those transactions that issue only consistent reads. Otherwise,
`InnoDB' cannot discard data from the update undo logs, and the
rollback segment may grow too big, filling up your tablespace.

The physical size of an undo log record in the rollback segment is
typically smaller than the corresponding inserted or updated row.  You
can use this information to calculate the space need for your rollback
segment.

In the `InnoDB' multi-versioning scheme, a row is not physically
removed from the database immediately when you delete it with an SQL
statement. Only when `InnoDB' can discard the update undo log record
written for the deletion can it also physically remove the
corresponding row and its index records from the database. This removal
operation is called a purge, and it is quite fast, usually taking the
same order of time as the SQL statement that did the deletion.

In a scenario where the user inserts and deletes rows in smallish
batches at about the same rate in the table, it is possible that the
purge thread starts to lag behind, and the table grows bigger and
bigger, making everything disk-bound and very slow. Even if the table
carries just 10MB of useful data, it may grow to occupy 10GB with all
the `dead' rows. In such a case, it would be good to throttle new row
operations, and allocate more resources to the purge thread. The
`innodb_max_purge_lag' system variable exists for exactly this purpose.
See *Note innodb-parameters::, for more information.


File: manual.info,  Node: innodb-table-and-index,  Next: file-space-management,  Prev: innodb-multi-versioning,  Up: innodb

13.5.13 `InnoDB' Table and Index Structures
-------------------------------------------

* Menu:

* innodb-physical-structure::    Physical Structure of an Index
* innodb-insert-buffering::      Insert Buffering
* innodb-adaptive-hash::         Adaptive Hash Indexes
* innodb-physical-record::       Physical Row Structure

MySQL stores its data dictionary information for tables in `.frm' files
in database directories. This is true for all MySQL storage engines.
But every `InnoDB' table also has its own entry in the `InnoDB'
internal data dictionary inside the tablespace. When MySQL drops a
table or a database, it has to delete both an `.frm' file or files, and
the corresponding entries inside the `InnoDB' data dictionary. This is
the reason why you cannot move `InnoDB' tables between databases simply
by moving the `.frm' files.

Every `InnoDB' table has a special index called the _clustered index_
where the data for the rows is stored. If you define a `PRIMARY KEY' on
your table, the index of the primary key is the clustered index.

If you do not define a `PRIMARY KEY' for your table, MySQL picks the
first `UNIQUE' index that has only `NOT NULL' columns as the primary key
and `InnoDB' uses it as the clustered index. If there is no such index
in the table, `InnoDB' internally generates a clustered index where the
rows are ordered by the row ID that `InnoDB' assigns to the rows in
such a table. The row ID is a 6-byte field that increases monotonically
as new rows are inserted. Thus, the rows ordered by the row ID are
physically in insertion order.

Accessing a row through the clustered index is fast because the row
data is on the same page where the index search leads. If a table is
large, the clustered index architecture often saves a disk I/O when
compared to the traditional solution. (In many database systems, data
storage uses a different page from the index record.)

In `InnoDB', the records in non-clustered indexes (also called
secondary indexes) contain the primary key value for the row. `InnoDB'
uses this primary key value to search for the row from the clustered
index. Note that if the primary key is long, the secondary indexes use
more space.

`InnoDB' compares `CHAR' and `VARCHAR' strings of different lengths
such that the remaining length in the shorter string is treated as if
padded with spaces.


File: manual.info,  Node: innodb-physical-structure,  Next: innodb-insert-buffering,  Prev: innodb-table-and-index,  Up: innodb-table-and-index

13.5.13.1 Physical Structure of an Index
........................................

All `InnoDB' indexes are B-trees where the index records are stored in
the leaf pages of the tree. The default size of an index page is 16KB.
When new records are inserted, `InnoDB' tries to leave 1/16 of the page
free for future insertions and updates of the index records.

If index records are inserted in a sequential order (ascending or
descending), the resulting index pages are about 15/16 full.  If
records are inserted in a random order, the pages are from 1/2 to 15/16
full. If the fill factor of an index page drops below 1/2, `InnoDB'
tries to contract the index tree to free the page.


File: manual.info,  Node: innodb-insert-buffering,  Next: innodb-adaptive-hash,  Prev: innodb-physical-structure,  Up: innodb-table-and-index

13.5.13.2 Insert Buffering
..........................

It is a common situation in database applications that the primary key
is a unique identifier and new rows are inserted in the ascending order
of the primary key. Thus, the insertions to the clustered index do not
require random reads from a disk.

On the other hand, secondary indexes are usually non-unique, and
insertions into secondary indexes happen in a relatively random order.
This would cause a lot of random disk I/O operations without a special
mechanism used in `InnoDB'.

If an index record should be inserted to a non-unique secondary index,
`InnoDB' checks whether the secondary index page is in the buffer pool.
If that is the case, `InnoDB' does the insertion directly to the index
page. If the index page is not found in the buffer pool, `InnoDB'
inserts the record to a special insert buffer structure. The insert
buffer is kept so small that it fits entirely in the buffer pool, and
insertions can be done very fast.

Periodically, the insert buffer is merged into the secondary index
trees in the database. Often it is possible to merge several insertions
to the same page of the index tree, saving disk I/O operations. It has
been measured that the insert buffer can speed up insertions into a
table up to 15 times.

The insert buffer merging may continue to happen _after_ the inserting
transaction has been committed. In fact, it may continue to happen
after a server shutdown and restart (see *Note forcing-recovery::).

The insert buffer merging may take many hours, when many secondary
indexes must be updated, and many rows have been inserted. During this
time, disk I/O will be increased, which can cause significant slowdown
on disk-bound queries. Another significant background I/O operation is
the purge thread (see *Note innodb-multi-versioning::).


File: manual.info,  Node: innodb-adaptive-hash,  Next: innodb-physical-record,  Prev: innodb-insert-buffering,  Up: innodb-table-and-index

13.5.13.3 Adaptive Hash Indexes
...............................

If a table fits almost entirely in main memory, the fastest way to
perform queries on it is to use hash indexes.  `InnoDB' has a mechanism
that monitors index searches made to the indexes defined for a table. If
`InnoDB' notices that queries could benefit from building a hash index,
it does so automatically.

Note that the hash index is always built based on an existing B-tree
index on the table. `InnoDB' can build a hash index on a prefix of any
length of the key defined for the B-tree, depending on the pattern of
searches that `InnoDB' observes for the B-tree index. A hash index can
be partial: It is not required that the whole B-tree index is cached in
the buffer pool. `InnoDB' builds hash indexes on demand for those pages
of the index that are often accessed.

In a sense, `InnoDB' tailors itself through the adaptive hash index
mechanism to ample main memory, coming closer to the architecture of
main-memory databases.


File: manual.info,  Node: innodb-physical-record,  Prev: innodb-adaptive-hash,  Up: innodb-table-and-index

13.5.13.4 Physical Row Structure
................................

The physical record structure for InnoDB tables is dependent on the row
format specified when the table was created. For MySQL 5.1, by default
InnoDB uses the `COMPACT' format, but the `REDUNDANT' format is
available to retain compatibility with older versions of MySQL.

Records in InnoDB `ROW_FORMAT=REDUNDANT' tables have the following
characteristics:

   * Each index record contains a six-byte header. The header is used
     to link together consecutive records, and also in row-level
     locking.

   * Records in the clustered index contain fields for all user-defined
     columns. In addition, there is a six-byte field for the
     transaction ID and a seven-byte field for the roll pointer.

   * If no primary key was defined for a table, each clustered index
     record also contains a six-byte row ID field.

   * Each secondary index record contains also all the fields defined
     for the clustered index key.

   * A record contains also a pointer to each field of the record. If
     the total length of the fields in a record is less than 128 bytes,
     the pointer is one byte; otherwise, two bytes. The array of these
     pointers is called the record directory. The area where these
     pointers point is called the data part of the record.

   * Internally, InnoDB stores fixed-length character columns such as
     `CHAR(10)' in a fixed-length format. InnoDB truncates trailing
     spaces from `VARCHAR' columns.

   * An SQL `NULL' value reserves 1 or 2 bytes in the record directory.
     Besides that, an SQL `NULL' value reserves zero bytes in the data
     part of the record if stored in a variable length column. In a
     fixed-length column, it reserves the fixed length of the column in
     the data part of the record. The motivation behind reserving the
     fixed space for `NULL' values is that it enables an update of the
     column from `NULL' to a non-`NULL' value to be done in place
     without causing fragmentation of the index page.

Records in InnoDB `ROW_FORMAT=COMPACT' tables have the following
characteristics:

   * Each index record contains a five-byte header that may be preceded
     by a variable-length header. The header is used to link together
     consecutive records, and also in row-level locking.

   * The record header contains a bit vector for indicating `NULL'
     columns. The bit vector occupies (`n_nullable'+7)/8 bytes. Columns
     that are `NULL' will not occupy other space than the bit in this
     vector.

   * For each non-`NULL' variable-length field, the record header
     contains the length of the column in one or two bytes. Two bytes
     will only be needed if part of the column is stored externally or
     the maximum length exceeds 255 bytes and the actual length exceeds
     127 bytes.

   * The record header is followed by the data contents of the columns.
     Columns that are `NULL' are omitted.

   * Records in the clustered index contain fields for all user-defined
     columns. In addition, there is a six-byte field for the
     transaction ID and a seven-byte field for the roll pointer.

   * If no primary key was defined for a table, each clustered index
     record also contains a six-byte row ID field.

   * Each secondary index record contains also all the fields defined
     for the clustered index key.

   * Internally, InnoDB stores fixed-length, fixed-width character
     columns such as `CHAR(10)' in a fixed-length format. InnoDB
     truncates trailing spaces from `VARCHAR' columns.

   * Internally, InnoDB attempts to store UTF-8 `CHAR(`n')' columns in
     `n' bytes by trimming trailing spaces. In `ROW_FORMAT=REDUNDANT',
     such columns occupy 3*`n' bytes. The motivation behind reserving
     the minimum space `n' is that it in many cases enables an update
     of the column to be done in place without causing fragmentation of
     the index page.

The presence of the compact row format decreases row storage space by
about 20% at the cost of increasing CPU use for some operations. If
your workload is a typical one that is limited by cache hit rates and
disk speed it is likely to be faster. If it is a rare case that is
limited by CPU speed, it might be slower.


File: manual.info,  Node: file-space-management,  Next: innodb-error-handling,  Prev: innodb-table-and-index,  Up: innodb

13.5.14 `InnoDB' File Space Management and Disk I/O
---------------------------------------------------

* Menu:

* innodb-disk-io::               `InnoDB' Disk I/O
* innodb-file-space::            File Space Management
* innodb-file-defragmenting::    Defragmenting a Table


File: manual.info,  Node: innodb-disk-io,  Next: innodb-file-space,  Prev: file-space-management,  Up: file-space-management

13.5.14.1 `InnoDB' Disk I/O
...........................

`InnoDB' uses simulated asynchronous disk I/O: `InnoDB' creates a
number of threads to take care of I/O operations, such as read-ahead.

There are two read-ahead heuristics in `InnoDB':

   * In sequential read-ahead, if `InnoDB' notices that the access
     pattern to a segment in the tablespace is sequential, it posts in
     advance a batch of reads of database pages to the I/O system.

   * In random read-ahead, if `InnoDB' notices that some area in a
     tablespace seems to be in the process of being fully read into the
     buffer pool, it posts the remaining reads to the I/O system.

`InnoDB' uses a novel file flush technique called _doublewrite_. It
adds safety to recovery following an operating system crash or a power
outage, and improves performance on most varieties of Unix by reducing
the need for `fsync()' operations.

Doublewrite means that before writing pages to a data file, `InnoDB'
first writes them to a contiguous tablespace area called the
doublewrite buffer. Only after the write and the flush to the
doublewrite buffer has completed does `InnoDB' write the pages to their
proper positions in the data file. If the operating system crashes in
the middle of a page write, `InnoDB' can later find a good copy of the
page from the doublewrite buffer during recovery.


File: manual.info,  Node: innodb-file-space,  Next: innodb-file-defragmenting,  Prev: innodb-disk-io,  Up: file-space-management

13.5.14.2 File Space Management
...............................

The data files that you define in the configuration file form the
tablespace of `InnoDB'. The files are simply concatenated to form the
tablespace. There is no striping in use. Currently, you cannot define
where within the tablespace your tables are allocated. However, in a
newly created tablespace, `InnoDB' allocates space starting from the
first data file.

The tablespace consists of database pages with a default size of 16KB.
The pages are grouped into extents of 64 consecutive pages. The `files'
inside a tablespace are called _segments_ in `InnoDB'.  The term
`rollback segment' is somewhat confusing because it actually contains
many tablespace segments.

Two segments are allocated for each index in `InnoDB'. One is for
non-leaf nodes of the B-tree, the other is for the leaf nodes. The idea
here is to achieve better sequentiality for the leaf nodes, which
contain the data.

When a segment grows inside the tablespace, `InnoDB' allocates the
first 32 pages to it individually. After that `InnoDB' starts to
allocate whole extents to the segment. `InnoDB' can add to a large
segment up to 4 extents at a time to ensure good sequentiality of data.

Some pages in the tablespace contain bitmaps of other pages, and
therefore a few extents in an `InnoDB' tablespace cannot be allocated
to segments as a whole, but only as individual pages.

When you ask for available free space in the tablespace by issuing a
`SHOW TABLE STATUS' statement, `InnoDB' reports the extents that are
definitely free in the tablespace. `InnoDB' always reserves some
extents for cleanup and other internal purposes; these reserved extents
are not included in the free space.

When you delete data from a table, `InnoDB' contracts the corresponding
B-tree indexes. Whether the freed space becomes available for other
users depends on whether the pattern of deletes frees individual pages
or extents to the tablespace. Dropping a table or deleting all rows
from it is guaranteed to release the space to other users, but remember
that deleted rows are physically removed only in an (automatic) purge
operation after they are no longer needed for transaction rollbacks or
consistent reads. (See *Note innodb-multi-versioning::.)


File: manual.info,  Node: innodb-file-defragmenting,  Prev: innodb-file-space,  Up: file-space-management

13.5.14.3 Defragmenting a Table
...............................

If there are random insertions into or deletions from the indexes of a
table, the indexes may become fragmented.  Fragmentation means that the
physical ordering of the index pages on the disk is not close to the
index ordering of the records on the pages, or that there are many
unused pages in the 64-page blocks that were allocated to the index.

A symptom of fragmentation is that a table takes more space than it
`should' take. How much that is exactly, is difficult to determine. All
`InnoDB' data and indexes are stored in B-trees, and their fill factor
may vary from 50% to 100%. Another symptom of fragmentation is that a
table scan such as this takes more time than it `should' take:

     SELECT COUNT(*) FROM t WHERE a_non_indexed_column <> 12345;

(In the preceding query, we are `fooling' the SQL optimizer into
scanning the clustered index, rather than a secondary index.) Most
disks can read 10 to 50MB/s, which can be used to estimate how fast a
table scan should run.

It can speed up index scans if you periodically perform a `null' `ALTER
TABLE' operation:

     ALTER TABLE TBL_NAME ENGINE=INNODB

That causes MySQL to rebuild the table. Another way to perform a
defragmentation operation is to use `mysqldump' to dump the table to a
text file, drop the table, and reload it from the dump file.

If the insertions to an index are always ascending and records are
deleted only from the end, the `InnoDB' filespace management algorithm
guarantees that fragmentation in the index does not occur.


File: manual.info,  Node: innodb-error-handling,  Next: innodb-restrictions,  Prev: file-space-management,  Up: innodb

13.5.15 `InnoDB' Error Handling
-------------------------------

* Menu:

* innodb-error-codes::           `InnoDB' Error Codes
* operating-system-error-codes::  Operating System Error Codes

Error handling in `InnoDB' is not always the same as specified in the
SQL standard. According to the standard, any error during an SQL
statement should cause the rollback of that statement. `InnoDB'
sometimes rolls back only part of the statement, or the whole
transaction. The following items describe how `InnoDB' performs error
handling:

   * If you run out of file space in the tablespace, a MySQL `Table is
     full' error occurs and `InnoDB' rolls back the SQL statement.

   * A transaction deadlock causes `InnoDB' to roll back the entire
     transaction. You should normally retry the whole transaction when
     this happens.

     A lock wait timeout causes `InnoDB' to roll back only the single
     statement that was waiting for the lock and encountered the
     timeout. (To have the entire transaction roll back, start the
     server with the `--innodb_rollback_on_timeout' option, available
     as of MySQL 5.1.15.) You should normally retry the statement if
     using the current behavior or the entire transaction if using
     `--innodb_rollback_on_timeout'.

     Both deadlocks and lock wait timeouts are normal on busy servers
     and it is necessary for applications to be aware that they may
     happen and handle them by retrying. You can make them less likely
     by doing as little work as possible between the first change to
     data during a transaction and the commit, so the locks are held
     for the shortest possible time and for the smallest possible
     number of rows. Sometimes splitting work between different
     transactions may be practical and helpful.

     When a transaction rollback occurs due to a deadlock or lock wait
     timeout, it cancels the effect of the statements within the
     transaction. But if the start-transaction statement was `START
     TRANSACTION' or `BEGIN' statement, rollback does not cancel that
     statement. Further SQL statements become part of the transaction
     until the occurrence of `COMMIT', `ROLLBACK', or some SQL
     statement that causes an implicit commit.

   * A duplicate-key error rolls back the SQL statement, if you have
     not specified the `IGNORE' option in your statement.

   * A `row too long error' rolls back the SQL statement.

   * Other errors are mostly detected by the MySQL layer of code (above
     the `InnoDB' storage engine level), and they roll back the
     corresponding SQL statement. Locks are not released in a rollback
     of a single SQL statement.

During implicit rollbacks, as well as during the execution of an
explicit `ROLLBACK' SQL statement, `SHOW PROCESSLIST' displays `Rolling
back' in the `State' column for the relevant connection.


File: manual.info,  Node: innodb-error-codes,  Next: operating-system-error-codes,  Prev: innodb-error-handling,  Up: innodb-error-handling

13.5.15.1 `InnoDB' Error Codes
..............................

The following is a non-exhaustive list of common `InnoDB'-specific
errors that you may encounter, with information about why each occurs
and how to resolve the problem.

   * `1005 (ER_CANT_CREATE_TABLE)'

     Cannot create table. If the error message refers to `errno' 150,
     table creation failed because a foreign key constraint was not
     correctly formed. If the error message refers to `errno' -1, table
     creation probably failed because the table includes a column name
     that matched the name of an internal InnoDB table.

   * `1016 (ER_CANT_OPEN_FILE)'

     Cannot find the `InnoDB' table from the `InnoDB' data files,
     although the `.frm' file for the table exists. See *Note
     innodb-troubleshooting-datadict::.

   * `1114 (ER_RECORD_FILE_FULL)'

     `InnoDB' has run out of free space in the tablespace. You should
     reconfigure the tablespace to add a new data file.

   * `1205 (ER_LOCK_WAIT_TIMEOUT)'

     Lock wait timeout expired. Transaction was rolled back.

   * `1213 (ER_LOCK_DEADLOCK)'

     Transaction deadlock. You should rerun the transaction.

   * `1216 (ER_NO_REFERENCED_ROW)'

     You are trying to add a row but there is no parent row, and a
     foreign key constraint fails. You should add the parent row first.

   * `1217 (ER_ROW_IS_REFERENCED)'

     You are trying to delete a parent row that has children, and a
     foreign key constraint fails. You should delete the children first.


File: manual.info,  Node: operating-system-error-codes,  Prev: innodb-error-codes,  Up: innodb-error-handling

13.5.15.2 Operating System Error Codes
......................................

To print the meaning of an operating system error number, use the
`perror' program that comes with the MySQL distribution.

The following table provides a list of some common Linux system error
codes. For a more complete list, see Linux source code
(http://www.iglu.org.il/lxr/source/include/asm-i386/errno.h).

   * `1 (EPERM)'

     Operation not permitted

   * `2 (ENOENT)'

     No such file or directory

   * `3 (ESRCH)'

     No such process

   * `4 (EINTR)'

     Interrupted system call

   * `5 (EIO)'

     I/O error

   * `6 (ENXIO)'

     No such device or address

   * `7 (E2BIG)'

     Arg list too long

   * `8 (ENOEXEC)'

     Exec format error

   * `9 (EBADF)'

     Bad file number

   * `10 (ECHILD)'

     No child processes

   * `11 (EAGAIN)'

     Try again

   * `12 (ENOMEM)'

     Out of memory

   * `13 (EACCES)'

     Permission denied

   * `14 (EFAULT)'

     Bad address

   * `15 (ENOTBLK)'

     Block device required

   * `16 (EBUSY)'

     Device or resource busy

   * `17 (EEXIST)'

     File exists

   * `18 (EXDEV)'

     Cross-device link

   * `19 (ENODEV)'

     No such device

   * `20 (ENOTDIR)'

     Not a directory

   * `21 (EISDIR)'

     Is a directory

   * `22 (EINVAL)'

     Invalid argument

   * `23 (ENFILE)'

     File table overflow

   * `24 (EMFILE)'

     Too many open files

   * `25 (ENOTTY)'

     Inappropriate ioctl for device

   * `26 (ETXTBSY)'

     Text file busy

   * `27 (EFBIG)'

     File too large

   * `28 (ENOSPC)'

     No space left on device

   * `29 (ESPIPE)'

     Illegal seek

   * `30 (EROFS)'

     Read-only file system

   * `31 (EMLINK)'

     Too many links

The following table provides a list of some common Windows system error
codes. For a complete list, see the Microsoft Web site
(http://msdn.microsoft.com/en-us/library/ms681381.aspx).

   * `1 (ERROR_INVALID_FUNCTION)'

     Incorrect function.

   * `2 (ERROR_FILE_NOT_FOUND)'

     The system cannot find the file specified.

   * `3 (ERROR_PATH_NOT_FOUND)'

     The system cannot find the path specified.

   * `4 (ERROR_TOO_MANY_OPEN_FILES)'

     The system cannot open the file.

   * `5 (ERROR_ACCESS_DENIED)'

     Access is denied.

   * `6 (ERROR_INVALID_HANDLE)'

     The handle is invalid.

   * `7 (ERROR_ARENA_TRASHED)'

     The storage control blocks were destroyed.

   * `8 (ERROR_NOT_ENOUGH_MEMORY)'

     Not enough storage is available to process this command.

   * `9 (ERROR_INVALID_BLOCK)'

     The storage control block address is invalid.

   * `10 (ERROR_BAD_ENVIRONMENT)'

     The environment is incorrect.

   * `11 (ERROR_BAD_FORMAT)'

     An attempt was made to load a program with an incorrect format.

   * `12 (ERROR_INVALID_ACCESS)'

     The access code is invalid.

   * `13 (ERROR_INVALID_DATA)'

     The data is invalid.

   * `14 (ERROR_OUTOFMEMORY)'

     Not enough storage is available to complete this operation.

   * `15 (ERROR_INVALID_DRIVE)'

     The system cannot find the drive specified.

   * `16 (ERROR_CURRENT_DIRECTORY)'

     The directory cannot be removed.

   * `17 (ERROR_NOT_SAME_DEVICE)'

     The system cannot move the file to a different disk drive.

   * `18 (ERROR_NO_MORE_FILES)'

     There are no more files.

   * `19 (ERROR_WRITE_PROTECT)'

     The media is write protected.

   * `20 (ERROR_BAD_UNIT)'

     The system cannot find the device specified.

   * `21 (ERROR_NOT_READY)'

     The device is not ready.

   * `22 (ERROR_BAD_COMMAND)'

     The device does not recognize the command.

   * `23 (ERROR_CRC)'

     Data error (cyclic redundancy check).

   * `24 (ERROR_BAD_LENGTH)'

     The program issued a command but the command length is incorrect.

   * `25 (ERROR_SEEK)'

     The drive cannot locate a specific area or track on the disk.

   * `26 (ERROR_NOT_DOS_DISK)'

     The specified disk or diskette cannot be accessed.

   * `27 (ERROR_SECTOR_NOT_FOUND)'

     The drive cannot find the sector requested.

   * `28 (ERROR_OUT_OF_PAPER)'

     The printer is out of paper.

   * `29 (ERROR_WRITE_FAULT)'

     The system cannot write to the specified device.

   * `30 (ERROR_READ_FAULT)'

     The system cannot read from the specified device.

   * `31 (ERROR_GEN_FAILURE)'

     A device attached to the system is not functioning.

   * `32 (ERROR_SHARING_VIOLATION)'

     The process cannot access the file because it is being used by
     another process.

   * `33 (ERROR_LOCK_VIOLATION)'

     The process cannot access the file because another process has
     locked a portion of the file.

   * `34 (ERROR_WRONG_DISK)'

     The wrong diskette is in the drive. Insert %2 (Volume Serial
     Number: %3) into drive %1.

   * `36 (ERROR_SHARING_BUFFER_EXCEEDED)'

     Too many files opened for sharing.

   * `38 (ERROR_HANDLE_EOF)'

     Reached the end of the file.

   * `39 (ERROR_HANDLE_DISK_FULL)'

     The disk is full.

   * `87 (ERROR_INVALID_PARAMETER)'

     The parameter is incorrect. (If this error occurs on Windows and
     you have enabled `innodb_file_per_table' in a server option file,
     add the line `innodb_flush_method=unbuffered' to the file as well.)

   * `112 (ERROR_DISK_FULL)'

     The disk is full.

   * `123 (ERROR_INVALID_NAME)'

     The filename, directory name, or volume label syntax is incorrect.

   * `1450 (ERROR_NO_SYSTEM_RESOURCES)'

     Insufficient system resources exist to complete the requested
     service.


File: manual.info,  Node: innodb-restrictions,  Next: innodb-troubleshooting,  Prev: innodb-error-handling,  Up: innodb

13.5.16 Restrictions on `InnoDB' Tables
---------------------------------------

   * *Warning*:

     Do _not_ convert MySQL system tables in the `mysql' database from
     `MyISAM' to `InnoDB' tables! This is an unsupported operation. If
     you do this, MySQL does not restart until you restore the old
     system tables from a backup or re-generate them with the
     `mysql_install_db' script.

   * *Warning*:

     It is not a good idea to configure `InnoDB' to use datafiles or
     logfiles on NFS volumes. Otherwise, the files might be locked by
     other processes and become unavailable for use by MySQL.

   * A table cannot contain more than 1000 columns.

   * The internal maximum key length is 3500 bytes, but MySQL itself
     restricts this to 3072 bytes.

   * Index key prefixes can be up to 767 bytes. See *Note
     create-index::.

   * The maximum row length, except for `VARBINARY', `VARCHAR', `BLOB'
     and `TEXT' columns, is slightly less than half of a database page.
     That is, the maximum row length is about 8000 bytes.  `LONGBLOB'
     and `LONGTEXT' columns must be less than 4GB, and the total row
     length, including also `BLOB' and `TEXT' columns, must be less
     than 4GB.  `InnoDB' stores the first 768 bytes of a `VARBINARY',
     `VARCHAR', `BLOB', or `TEXT' column in the row, and the rest into
     separate pages.

   * Although `InnoDB' supports row sizes larger than 65535 internally,
     you cannot define a row containing `VARBINARY' or `VARCHAR'
     columns with a combined size larger than 65535:

          mysql> CREATE TABLE t (a VARCHAR(8000), b VARCHAR(10000),
              -> c VARCHAR(10000), d VARCHAR(10000), e VARCHAR(10000),
              -> f VARCHAR(10000), g VARCHAR(10000)) ENGINE=InnoDB;
          ERROR 1118 (42000): Row size too large. The maximum row size for the
          used table type, not counting BLOBs, is 65535. You have to change some
          columns to TEXT or BLOBs

   * On some older operating systems, files must be less than 2GB.
     This is not a limitation of `InnoDB' itself, but if you require a
     large tablespace, you will need to configure it using several
     smaller data files rather than one or a file large data files.

   * The combined size of the `InnoDB' log files must be less than 4GB.

   * The minimum tablespace size is 10MB. The maximum tablespace size
     is four billion database pages (64TB). This is also the maximum
     size for a table.

   * `InnoDB' tables do not support `FULLTEXT' indexes.

   * `InnoDB' tables support spatial types, but not indexes on them.

   * `ANALYZE TABLE' determines index cardinality (as displayed in the
     `Cardinality' column of `SHOW INDEX' output) by doing ten random
     dives to each of the index trees and updating index cardinality
     estimates accordingly. Note that because these are only estimates,
     repeated runs of `ANALYZE TABLE' may produce different numbers.
     This makes `ANALYZE TABLE' fast on `InnoDB' tables but not 100%
     accurate as it doesn't take all rows into account.

     MySQL uses index cardinality estimates only in join optimization.
     If some join is not optimized in the right way, you can try using
     `ANALYZE TABLE'. In the few cases that `ANALYZE TABLE' doesn't
     produce values good enough for your particular tables, you can use
     `FORCE INDEX' with your queries to force the use of a particular
     index, or set the `max_seeks_for_key' system variable to ensure
     that MySQL prefers index lookups over table scans. See *Note
     server-system-variables::, and *Note optimizer-issues::.

   * `SHOW TABLE STATUS' does not give accurate statistics on `InnoDB'
     tables, except for the physical size reserved by the table. The
     row count is only a rough estimate used in SQL optimization.

   * `InnoDB' does not keep an internal count of rows in a table. (In
     practice, this would be somewhat complicated due to
     multi-versioning.) To process a `SELECT COUNT(*) FROM t' statement,
     `InnoDB' must scan an index of the table, which takes some time if
     the index is not entirely in the buffer pool. To get a fast count,
     you have to use a counter table you create yourself and let your
     application update it according to the inserts and deletes it
     does. If your table does not change often, using the MySQL query
     cache is a good solution. `SHOW TABLE STATUS' also can be used if
     an approximate row count is sufficient. See *Note innodb-tuning::.

   * On Windows, `InnoDB' always stores database and table names
     internally in lowercase. To move databases in binary format from
     Unix to Windows or from Windows to Unix, you should always use
     explicitly lowercase names when creating databases and tables.

   * For an `AUTO_INCREMENT' column, you must always define an index
     for the table, and that index must contain just the
     `AUTO_INCREMENT' column. In `MyISAM' tables, the `AUTO_INCREMENT'
     column may be part of a multi-column index.

   * While initializing a previously specified `AUTO_INCREMENT' column
     on a table, `InnoDB' sets an exclusive lock on the end of the
     index associated with the `AUTO_INCREMENT' column. In accessing the
     auto-increment counter, `InnoDB' uses a specific table lock mode
     `AUTO-INC' where the lock lasts only to the end of the current SQL
     statement, not to the end of the entire transaction. Note that
     other clients cannot insert into the table while the `AUTO-INC'
     table lock is held; see *Note innodb-and-autocommit::.

   * When you restart the MySQL server, `InnoDB' may reuse an old value
     that was generated for an `AUTO_INCREMENT' column but never stored
     (that is, a value that was generated during an old transaction
     that was rolled back).

   * When an `AUTO_INCREMENT' column runs out of values, `InnoDB' wraps
     a `BIGINT' to `-9223372036854775808' and `BIGINT UNSIGNED' to `1'.
     However, `BIGINT' values have 64 bits, so do note that if you were
     to insert one million rows per second, it would still take nearly
     three hundred thousand years before `BIGINT' reached its upper
     bound. With all other integer type columns, a duplicate-key error
     results.  This is similar to how `MyISAM' works, because it is
     mostly general MySQL behavior and not about any storage engine in
     particular.

   * `DELETE FROM TBL_NAME' does not regenerate the table but instead
     deletes all rows, one by one.

   * Under some conditions, `TRUNCATE TBL_NAME' for an `InnoDB' table
     is mapped to `DELETE FROM TBL_NAME' and doesn't reset the
     `AUTO_INCREMENT' counter. See *Note truncate::.

   * In MySQL 5.1, the MySQL `LOCK TABLES' operation acquires two locks
     on each table if `innodb_table_locks=1' (the default). In addition
     to a table lock on the MySQL layer, it also acquires an `InnoDB'
     table lock. Older versions of MySQL did not acquire `InnoDB' table
     locks; the old behavior can be selected by setting
     `innodb_table_locks=0'. If no `InnoDB' table lock is acquired,
     `LOCK TABLES' completes even if some records of the tables are
     being locked by other transactions.

   * All `InnoDB' locks held by a transaction are released when the
     transaction is committed or aborted. Thus, it does not make much
     sense to invoke `LOCK TABLES' on `InnoDB' tables in `AUTOCOMMIT=1'
     mode, because the acquired `InnoDB' table locks would be released
     immediately.

   * Sometimes it would be useful to lock further tables in the course
     of a transaction. Unfortunately, `LOCK TABLES' in MySQL performs
     an implicit `COMMIT' and `UNLOCK TABLES'. An `InnoDB' variant of
     `LOCK TABLES' has been planned that can be executed in the middle
     of a transaction.

   * The `LOAD TABLE FROM MASTER' statement for setting up replication
     slave servers does not work for `InnoDB' tables. A workaround is
     to alter the table to `MyISAM' on the master, then do the load,
     and after that alter the master table back to `InnoDB'. Do not do
     this if the tables use `InnoDB'-specific features such as foreign
     keys.

   * The default database page size in `InnoDB' is 16KB. By recompiling
     the code, you can set it to values ranging from 8KB to 64KB. You
     must update the values of `UNIV_PAGE_SIZE' and
     `UNIV_PAGE_SIZE_SHIFT' in the `univ.i' source file.

   * Currently, triggers are not activated by cascaded foreign key
     actions.

   * `InnoDB' has a limit of 1023 concurrent transactions that have
     created undo records by modifying data.  Workarounds include
     keeping transactions as small and fast as possible, delaying
     changes until near the end of the transaction, and using stored
     routines to reduce client-server latency delays. Applications
     should commit transactions before doing time-consuming client-side
     operations.


File: manual.info,  Node: innodb-troubleshooting,  Prev: innodb-restrictions,  Up: innodb

13.5.17 `InnoDB' Troubleshooting
--------------------------------

* Menu:

* innodb-troubleshooting-datadict::  Troubleshooting `InnoDB' Data Dictionary Operations

The following general guidelines apply to troubleshooting `InnoDB'
problems:

   * When an operation fails or you suspect a bug, you should look at
     the MySQL server error log, which is the file in the data
     directory that has a suffix of `.err'.

   * When troubleshooting, it is usually best to run the MySQL server
     from the command prompt, rather than through the `mysqld_safe'
     wrapper or as a Windows service. You can then see what `mysqld'
     prints to the console, and so have a better grasp of what is going
     on. On Windows, you must start the server with the `--console'
     option to direct the output to the console window.

   * Use the `InnoDB' Monitors to obtain information about a problem
     (see *Note innodb-monitor::). If the problem is
     performance-related, or your server appears to be hung, you should
     use `innodb_monitor' to print information about the internal state
     of `InnoDB'. If the problem is with locks, use
     `innodb_lock_monitor'. If the problem is in creation of tables or
     other data dictionary operations, use `innodb_table_monitor' to
     print the contents of the `InnoDB' internal data dictionary.

   * If you suspect that a table is corrupt, run `CHECK TABLE' on that
     table.

MySQL Enterprise

The MySQL Enterprise Monitor provides a number of advisors specifically
designed for monitoring InnoDB tables. In some cases, these advisors
can anticipate potential problems. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: innodb-troubleshooting-datadict,  Prev: innodb-troubleshooting,  Up: innodb-troubleshooting

13.5.17.1 Troubleshooting `InnoDB' Data Dictionary Operations
.............................................................

A specific issue with tables is that the MySQL server keeps data
dictionary information in `.frm' files it stores in the database
directories, whereas `InnoDB' also stores the information into its own
data dictionary inside the tablespace files. If you move `.frm' files
around, or if the server crashes in the middle of a data dictionary
operation, the locations of the `.frm' files may end up out of synchrony
with the locations recorded in the `InnoDB' internal data dictionary.

A symptom of an out-of-sync data dictionary is that a `CREATE TABLE'
statement fails. If this occurs, you should look in the server's error
log. If the log says that the table already exists inside the `InnoDB'
internal data dictionary, you have an orphaned table inside the
`InnoDB' tablespace files that has no corresponding `.frm' file. The
error message looks like this:

     InnoDB: Error: table test/parent already exists in InnoDB internal
     InnoDB: data dictionary. Have you deleted the .frm file
     InnoDB: and not used DROP TABLE? Have you used DROP DATABASE
     InnoDB: for InnoDB tables in MySQL version <= 3.23.43?
     InnoDB: See the Restrictions section of the InnoDB manual.
     InnoDB: You can drop the orphaned table inside InnoDB by
     InnoDB: creating an InnoDB table with the same name in another
     InnoDB: database and moving the .frm file to the current database.
     InnoDB: Then MySQL thinks the table exists, and DROP TABLE will
     InnoDB: succeed.

You can drop the orphaned table by following the instructions given in
the error message. If you are still unable to use `DROP TABLE'
successfully, the problem may be due to name completion in the `mysql'
client.  To work around this problem, start the `mysql' client with the
`--skip-auto-rehash' option and try `DROP TABLE' again. (With name
completion on, `mysql' tries to construct a list of table names, which
fails when a problem such as just described exists.)

Another symptom of an out-of-sync data dictionary is that MySQL prints
an error that it cannot open a `.InnoDB' file:

     ERROR 1016: Can't open file: 'child2.InnoDB'. (errno: 1)

In the error log you can find a message like this:

     InnoDB: Cannot find table test/child2 from the internal data dictionary
     InnoDB: of InnoDB though the .frm file for the table exists. Maybe you
     InnoDB: have deleted and recreated InnoDB data files but have forgotten
     InnoDB: to delete the corresponding .frm files of InnoDB tables?

This means that there is an orphaned `.frm' file without a
corresponding table inside `InnoDB'. You can drop the orphaned `.frm'
file by deleting it manually.

If MySQL crashes in the middle of an `ALTER TABLE' operation, you may
end up with an orphaned temporary table inside the `InnoDB' tablespace.
Using `innodb_table_monitor' you can see listed a table whose name is
`#sql-...'. You can perform SQL statements on tables whose name
contains the character ``#'' if you enclose the name within backticks.
Thus, you can drop such an orphaned table like any other orphaned table
using the method described earlier. Note that to copy or rename a file
in the Unix shell, you need to put the file name in double quotes if
the file name contains ``#''.


File: manual.info,  Node: merge-storage-engine,  Next: memory-storage-engine,  Prev: innodb,  Up: storage-engines

13.6 The `MERGE' Storage Engine
===============================

* Menu:

* merge-table-problems::         `MERGE' Table Problems

The `MERGE' storage engine, also known as the `MRG_MyISAM' engine, is a
collection of identical `MyISAM' tables that can be used as one.
`Identical' means that all tables have identical column and index
information. You cannot merge `MyISAM' tables in which the columns are
listed in a different order, do not have exactly the same columns, or
have the indexes in different order. However, any or all of the
`MyISAM' tables can be compressed with `myisampack'. See *Note
myisampack::. Differences in table options such as `AVG_ROW_LENGTH',
`MAX_ROWS', or `PACK_KEYS' do not matter.

When you create a `MERGE' table, MySQL creates two files on disk. The
files have names that begin with the table name and have an extension
to indicate the file type. An `.frm' file stores the table format, and
an `.MRG' file contains the names of the tables that should be used as
one. The tables do not have to be in the same database as the `MERGE'
table itself.

You can use `SELECT', `DELETE', `UPDATE', and `INSERT' on `MERGE'
tables. You must have `SELECT', `UPDATE', and `DELETE' privileges on the
`MyISAM' tables that you map to a `MERGE' table.

*Note*:

The use of `MERGE' tables entails the following security issue: If a
user has access to `MyISAM' table T, that user can create a `MERGE'
table M that accesses T. However, if the user's privileges on T are
subsequently revoked, the user can continue to access T by doing so
through M. If this behavior is undesirable, you can start the server
with the new `--skip-merge' option to disable the `MERGE' storage
engine.  This option is available as of MySQL 5.1.12.

If you `DROP' the `MERGE' table, you are dropping only the `MERGE'
specification.  The underlying tables are not affected.

To create a `MERGE' table, you must specify a `UNION=(LIST-OF-TABLES)'
clause that indicates which `MyISAM' tables you want to use as one. You
can optionally specify an `INSERT_METHOD' option if you want inserts
for the `MERGE' table to take place in the first or last table of the
`UNION' list. Use a value of `FIRST' or `LAST' to cause inserts to be
made in the first or last table, respectively. If you do not specify an
`INSERT_METHOD' option or if you specify it with a value of `NO',
attempts to insert rows into the `MERGE' table result in an error.

The following example shows how to create a `MERGE' table:

     mysql> CREATE TABLE t1 (
         ->    a INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
         ->    message CHAR(20)) ENGINE=MyISAM;
     mysql> CREATE TABLE t2 (
         ->    a INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
         ->    message CHAR(20)) ENGINE=MyISAM;
     mysql> INSERT INTO t1 (message) VALUES ('Testing'),('table'),('t1');
     mysql> INSERT INTO t2 (message) VALUES ('Testing'),('table'),('t2');
     mysql> CREATE TABLE total (
         ->    a INT NOT NULL AUTO_INCREMENT,
         ->    message CHAR(20), INDEX(a))
         ->    ENGINE=MERGE UNION=(t1,t2) INSERT_METHOD=LAST;

Note that the `a' column is indexed as a `PRIMARY KEY' in the underlying
`MyISAM' tables, but not in the `MERGE' table. There it is indexed but
not as a `PRIMARY KEY' because a `MERGE' table cannot enforce
uniqueness over the set of underlying tables.

In MySQL 5.1.15 and later, when a table that is part of a `MERGE' table
is opened, the following checks are applied before opening each table.
If any table fails the conformance checks, then the operation that
triggered the opening of the table will fail. The conformance checks
applied to each table are:

   * Table must have exactly the same amount of columns that `MERGE'
     table has.

   * Column order in the `MERGE' table must match the column order in
     the underlying tables.

   * Additionally, the specification for each column in the parent
     `MERGE' table and the underlying table are compared. For each
     column, MySQL checks:

        * Column type in the underlying table equals the column type of
          `MERGE' table.

        * Column length in the underlying table equals the column
          length of `MERGE' table.

        * Column of underlying table and column of `MERGE' table can be
          `NULL'.

   * Underlying table must have at least the same amount of keys that
     merge table has. The underlying table may have morekeys than the
     `MERGE' table, but cannot have less.

     *Note*:

     A known issue exists that keys on the some columns must be
     identical in order in both the `MERGE' table and the underlying
     `MyISAM' table. See Bug#33653 (http://bugs.mysql.com/33653).

     For each key:

        * Check if the key type of underlying table equals the key type
          of merge table.

        * Check if number of key parts (i.e. multiple columns within a
          compound key) in the underlying table key definition equals
          the number of key parts in merge table key definition.

        * For each key part:

             * Check if key part lengths are equal.

             * Check if key part types are equal.

             * Check if key part languages are equal.

             * Check if key part can be `NULL'.

After creating the `MERGE' table, you can issue queries that operate on
the group of tables as a whole:

     mysql> SELECT * FROM total;
     +---+---------+
     | a | message |
     +---+---------+
     | 1 | Testing |
     | 2 | table   |
     | 3 | t1      |
     | 1 | Testing |
     | 2 | table   |
     | 3 | t2      |
     +---+---------+

To remap a `MERGE' table to a different collection of `MyISAM' tables,
you can use one of the following methods:

   * `DROP' the `MERGE' table and re-create it.

   * Use `ALTER TABLE TBL_NAME UNION=(...)' to change the list of
     underlying tables.

     Beginning with MySQL 5.1.24, it is also possible to use `ALTER
     TABLE ... UNION=()' (that is, with an empty `UNION' clause) to
     remove all of the underlying tables. (Bug#28248
     (http://bugs.mysql.com/28248))

`MERGE' tables can help you solve the following problems:

   * Easily manage a set of log tables. For example, you can put data
     from different months into separate tables, compress some of them
     with `myisampack', and then create a `MERGE' table to use them as
     one.

   * Obtain more speed. You can split a big read-only table based on
     some criteria, and then put individual tables on different disks.
     A `MERGE' table on this could be much faster than using the big
     table.

   * Perform more efficient searches. If you know exactly what you are
     looking for, you can search in just one of the split tables for
     some queries and use a `MERGE' table for others. You can even have
     many different `MERGE' tables that use overlapping sets of tables.

   * Perform more efficient repairs. It is easier to repair individual
     tables that are mapped to a `MERGE' table than to repair a single
     large table.

   * Instantly map many tables as one. A `MERGE' table need not
     maintain an index of its own because it uses the indexes of the
     individual tables. As a result, `MERGE' table collections are
     _very_ fast to create or remap. (Note that you must still specify
     the index definitions when you create a `MERGE' table, even though
     no indexes are created.)

   * If you have a set of tables from which you create a large table on
     demand, you should instead create a `MERGE' table on them on
     demand. This is much faster and saves a lot of disk space.

   * Exceed the file size limit for the operating system. Each `MyISAM'
     table is bound by this limit, but a collection of `MyISAM' tables
     is not.

   * You can create an alias or synonym for a `MyISAM' table by
     defining a `MERGE' table that maps to that single table.  There
     should be no really notable performance impact from doing this
     (only a couple of indirect calls and `memcpy()' calls for each
     read).

The disadvantages of `MERGE' tables are:

   * You can use only identical `MyISAM' tables for a `MERGE' table.

   * You cannot use a number of `MyISAM' features in `MERGE' tables.
     For example, you cannot create `FULLTEXT' indexes on `MERGE'
     tables. (You can, of course, create `FULLTEXT' indexes on the
     underlying `MyISAM' tables, but you cannot search the `MERGE'
     table with a full-text search.)

   * If the `MERGE' table is non-temporary, all underlying `MyISAM'
     tables must be non-temporary, too. If the `MERGE' table is
     temporary, the `MyISAM' tables can be any mix of temporary and
     non-temporary.

   * `MERGE' tables use more file descriptors. If 10 clients are using
     a `MERGE' table that maps to 10 tables, the server uses (10 x 10)
     + 10 file descriptors. (10 data file descriptors for each of the 10
     clients, and 10 index file descriptors shared among the clients.)

   * Key reads are slower. When you read a key, the `MERGE' storage
     engine needs to issue a read on all underlying tables to check
     which one most closely matches the given key. To read the next
     key, the `MERGE' storage engine needs to search the read buffers
     to find the next key. Only when one key buffer is used up does the
     storage engine need to read the next key block. This makes `MERGE'
     keys much slower on `eq_ref' searches, but not much slower on
     `ref' searches. See *Note explain::, for more information about
     `eq_ref' and `ref'.

*Additional resources*

   * A forum dedicated to the `MERGE' storage engine is available at
     `http://forums.mysql.com/list.php?93'.


File: manual.info,  Node: merge-table-problems,  Prev: merge-storage-engine,  Up: merge-storage-engine

13.6.1 `MERGE' Table Problems
-----------------------------

The following are known problems with `MERGE' tables:

   * If you use `ALTER TABLE' to change a `MERGE' table to another
     storage engine, the mapping to the underlying tables is lost.
     Instead, the rows from the underlying `MyISAM' tables are copied
     into the altered table, which then uses the specified storage
     engine.

   * `REPLACE' does not work as expected because the `MERGE' engine
     cannot enforce uniqueness over the set of underlying tables. The
     two key facts are:

        * `REPLACE' can detect unique key violations only in the
          underlying table to which it is going to write (which is
          determined by `INSERT_METHOD'). This differs from violations
          in the `MERGE' table itself.

        * If `REPLACE' detects such a violation, it will only change
          the corresponding row in the first underlying table in which
          the row is present, whereas a row with the same unique key
          value may be present in all underlying tables.

     Similar considerations apply for `INSERT ... ON DUPLICATE KEY
     UPDATE'.

   * `MERGE' tables do not support partitioning.  That is, you cannot
     partition a `MERGE' table, nor can any of a `MERGE' table's
     underlying `MyISAM' tables be partitioned.

   * You cannot use `REPAIR TABLE', `OPTIMIZE TABLE', `DROP TABLE',
     `ALTER TABLE', `DELETE' without a `WHERE' clause, `TRUNCATE
     TABLE', or `ANALYZE TABLE' on any of the tables that are mapped
     into an open `MERGE' table. If you do so, the `MERGE' table may
     still refer to the original table, which yields unexpected
     results. The easiest way to work around this deficiency is to
     ensure that no `MERGE' tables remain open by issuing a `FLUSH
     TABLES' statement prior to performing any of those operations.

     The unexpected results include the possibility that the operation
     on the `MERGE' table will report table corruption. However, if
     this occurs after operations on the underlying `MyISAM' tables
     such as those listed in the previous paragraph (`REPAIR TABLE',
     `OPTIMIZE TABLE', and so forth), the corruption message is
     spurious. To deal with this, issue a `FLUSH TABLES' statement after
     modifying the `MyISAM' tables.

   * `DROP TABLE' on a table that is in use by a `MERGE' table does not
     work on Windows because the `MERGE' storage engine's table mapping
     is hidden from the upper layer of MySQL. Windows does not allow
     open files to be deleted, so you first must flush all `MERGE'
     tables (with `FLUSH TABLES') or drop the `MERGE' table before
     dropping the table.

   * A `MERGE' table cannot maintain uniqueness constraints over the
     entire table. When you perform an `INSERT', the data goes into the
     first or last `MyISAM' table (depending on the value of the
     `INSERT_METHOD' option). MySQL ensures that unique key values
     remain unique within that `MyISAM' table, but not across all the
     tables in the collection.

   * The `INSERT_METHOD' table option for a `MERGE' table indicates
     which underlying `MyISAM' table to use for inserts into the
     `MERGE' table. However, use of the `AUTO_INCREMENT' table option
     for that `MyISAM' table has no effect for inserts into the `MERGE'
     table until at least one row has been inserted directly into the
     `MyISAM' table.

   * In MySQL 5.1.15 and later, the definition of the `MyISAM' tables
     and the `MERGE' table are checked when the tables are accessed
     (for example, as part of a `SELECT' or `INSERT' statement). The
     checks ensure that the definitions of the tables and the parent
     `MERGE' table definition match by comparing column order, types,
     sizes and associated indexes. If there is a difference between the
     tables then an error will be returned and the statement will fail.

     Because these checks take place when the tables are opened, any
     changes to the definition of a single table, including column
     changes, column ordering and engine alterations will cause the
     statement to fail.

     In MySQL 5.1.14 and earlier:

        * When you create or alter `MERGE' table, there is no check to
          ensure that the underlying tables are existing `MyISAM'
          tables and have identical structures. When the `MERGE' table
          is used, MySQL checks that the row length for all mapped
          tables is equal, but this is not foolproof. If you create a
          `MERGE' table from dissimilar `MyISAM' tables, you are very
          likely to run into strange problems.

        * Similarly, if you create a `MERGE' table from non-`MyISAM'
          tables, or if you drop an underlying table or alter it to be a
          non-`MyISAM' table, no error for the `MERGE' table occurs
          until later when you attempt to use it.

        * Because the underlying `MyISAM' tables need not exist when
          the `MERGE' table is created, you can create the tables in
          any order, as long as you do not use the `MERGE' table until
          all of its underlying tables are in place. Also, if you can
          ensure that a `MERGE' table will not be used during a given
          period, you can perform maintenance operations on the
          underlying tables, such as backing up or restoring them,
          altering them, or dropping and recreating them. It is not
          necessary to redefine the `MERGE' table temporarily to
          exclude the underlying tables while you are operating on them.

   * The order of indexes in the `MERGE' table and its underlying
     tables should be the same. If you use `ALTER TABLE' to add a
     `UNIQUE' index to a table used in a `MERGE' table, and then use
     `ALTER TABLE' to add a non-unique index on the `MERGE' table, the
     index ordering is different for the tables if there was already a
     non-unique index in the underlying table. (This happens because
     `ALTER TABLE' puts `UNIQUE' indexes before non-unique indexes to
     facilitate rapid detection of duplicate keys.) Consequently,
     queries on tables with such indexes may return unexpected results.

   * If you encounter an error message similar to `ERROR 1017 (HY000):
     Can't find file: 'MM.MRG' (errno: 2)' it generally indicates that
     some of the base tables are not using the `MyISAM' storage engine.
     Confirm that all of these tables are `MyISAM'.

   * The maximum number of rows in a `MERGE' table is 2^64 (~1.844E+19;
     the same as for a `MyISAM' table), provided that the server was
     built using the `--with-big-tables' option.  (All standard MySQL
     5.1 standard binaries are built with this option; for more
     information, see *Note configure-options::.) It is not possible to
     merge multiple `MyISAM' tables into a single `MERGE' table that
     would have more than this number of rows.

   * The `MERGE' storage engine does not support `INSERT DELAYED'
     statements.

   * Using different underlying row formats in `MyISAM' tables with a
     parent `MERGE' table is currently known to fail. See Bug#32364
     (http://bugs.mysql.com/32364)

   * As of MySQL 5.1.20, if a `MERGE' table cannot be opened or used
     because of a problem with an underlying table, `CHECK TABLE'
     displays information about which table caused the problem.

   * Starting with MySQL 5.1.23, you cannot change the union list of a
     non-temporary `MERGE' table when LOCK TABLES is in effect. The
     following does _not_ work:

          CREATE TABLE m1 ... ENGINE=MRG_MYISAM ...;
          LOCK TABLES t1 WRITE, t2 WRITE, m1 WRITE;
          ALTER TABLE m1 ... UNION=(t1,t2) ...;

     However, you can do this with a temporary `MERGE' table.

   * Starting with MySQL 5.1.23, you cannot create a `MERGE' table with
     `CREATE ...  SELECT', neither as a temporary `MERGE' table, nor as
     a non-temporary `MERGE' table. For example:

          CREATE TABLE m1 ... ENGINE=MRG_MYISAM ... SELECT ...;

     Gives error message: table is not `BASE TABLE'.


File: manual.info,  Node: memory-storage-engine,  Next: example-storage-engine,  Prev: merge-storage-engine,  Up: storage-engines

13.7 The `MEMORY' (`HEAP') Storage Engine
=========================================

The `MEMORY' storage engine creates tables with contents that are
stored in memory. Formerly, these were known as `HEAP' tables. `MEMORY'
is the preferred term, although `HEAP' remains supported for backward
compatibility.

Each `MEMORY' table is associated with one disk file. The filename
begins with the table name and has an extension of `.frm' to indicate
that it stores the table definition.

To specify explicitly that you want to create a `MEMORY' table,
indicate that with an `ENGINE' table option:

     CREATE TABLE t (i INT) ENGINE = MEMORY;

As indicated by the name, `MEMORY' tables are stored in memory. They
use hash indexes by default, which makes them very fast, and very
useful for creating temporary tables. However, when the server shuts
down, all rows stored in `MEMORY' tables are lost. The tables themselves
continue to exist because their definitions are stored in `.frm' files
on disk, but they are empty when the server restarts.

This example shows how you might create, use, and remove a `MEMORY'
table:

     mysql> CREATE TABLE test ENGINE=MEMORY
         ->     SELECT ip,SUM(downloads) AS down
         ->     FROM log_table GROUP BY ip;
     mysql> SELECT COUNT(ip),AVG(down) FROM test;
     mysql> DROP TABLE test;

`MEMORY' tables have the following characteristics:

   * Space for `MEMORY' tables is allocated in small blocks. Tables use
     100% dynamic hashing for inserts. No overflow area or extra key
     space is needed. No extra space is needed for free lists. Deleted
     rows are put in a linked list and are reused when you insert new
     data into the table.  `MEMORY' tables also have none of the
     problems commonly associated with deletes plus inserts in hashed
     tables.

   * `MEMORY' tables can have up to 32 indexes per table, 16 columns
     per index and a maximum key length of 500 bytes.

   * The `MEMORY' storage engine implements both `HASH' and `BTREE'
     indexes.  You can specify one or the other for a given index by
     adding a `USING' clause as shown here:

          CREATE TABLE lookup
              (id INT, INDEX USING HASH (id))
              ENGINE = MEMORY;
          CREATE TABLE lookup
              (id INT, INDEX USING BTREE (id))
              ENGINE = MEMORY;

     General characteristics of B-tree and hash indexes are described
     in *Note mysql-indexes::.

   * You can have non-unique keys in a `MEMORY' table. (This is an
     uncommon feature for implementations of hash indexes.)

   * If you have a hash index on a `MEMORY' table that has a high
     degree of key duplication (many index entries containing the same
     value), updates to the table that affect key values and all
     deletes are significantly slower. The degree of this slowdown is
     proportional to the degree of duplication (or, inversely
     proportional to the index cardinality). You can use a `BTREE'
     index to avoid this problem.

   * Columns that are indexed can contain `NULL' values.

   * `MEMORY' tables use a fixed-length row storage format.

   * `MEMORY' tables cannot contain `BLOB' or `TEXT' columns.

   * `MEMORY' includes support for `AUTO_INCREMENT' columns.

   * You can use `INSERT DELAYED' with `MEMORY' tables. See *Note
     insert-delayed::.

   * `MEMORY' tables are shared among all clients (just like any other
     non-`TEMPORARY' table).

   * `MEMORY' table contents are stored in memory, which is a property
     that `MEMORY' tables share with internal tables that the server
     creates on the fly while processing queries. However, the two
     types of tables differ in that `MEMORY' tables are not subject to
     storage conversion, whereas internal tables are:

        * If an internal table becomes too large, the server
          automatically converts it to an on-disk table. The size limit
          is determined by the value of the `tmp_table_size' system
          variable.

        * `MEMORY' tables are never converted to disk tables.

        * The maximum size of `MEMORY' tables is limited by the
          `max_heap_table_size' system variable, which has a default
          value of 16MB. To have larger (or smaller) `MEMORY' tables,
          you must change the value of this variable. The value in
          effect at the time a `MEMORY' table is created is the value
          used for the life of the table. (If you use `ALTER TABLE' or
          `TRUNCATE TABLE', the value in effect at that time becomes
          the new maximum size for the table. A server restart also
          sets the maximum size of existing `MEMORY' tables to the
          global `max_heap_table_size' value.) You can set the size for
          individual tables as described later in this section.

   * The server needs sufficient memory to maintain all `MEMORY' tables
     that are in use at the same time.

   * Memory used by a `MEMORY' table is not reclaimed if you delete
     individual rows from the table. Memory is only reclaimed when the
     entire table is deleted. Memory that was previously used for rows
     that have been deleted will be re-used for new rows only within
     the same table. To free up the memory used by rows that have been
     deleted you should use `ALTER TABLE ENGINE=MEMORY' to force a table
     rebuild.

     To free all the memory used by a `MEMORY' table when you no longer
     require its contents, you should execute `DELETE' or `TRUNCATE
     TABLE', or remove the table altogether using `DROP TABLE'.

   * If you want to populate a `MEMORY' table when the MySQL server
     starts, you can use the `--init-file' option. For example, you can
     put statements such as `INSERT INTO ... SELECT' or `LOAD DATA
     INFILE' into this file to load the table from a persistent data
     source. See *Note server-options::, and *Note load-data::.

   * If you are using replication, the master server's `MEMORY' tables
     become empty when it is shut down and restarted. However, a slave
     is not aware that these tables have become empty, so it returns
     out-of-date content if you select data from them. When a `MEMORY'
     table is used on the master for the first time since the master
     was started, a `DELETE' statement is written to the master's
     binary log automatically, thus synchronizing the slave to the
     master again. Note that even with this strategy, the slave still
     has outdated data in the table during the interval between the
     master's restart and its first use of the table. However, if you
     use the `--init-file' option to populate the `MEMORY' table on the
     master at startup, it ensures that this time interval is zero.

   * The memory needed for one row in a `MEMORY' table is calculated
     using the following expression:

          SUM_OVER_ALL_BTREE_KEYS(MAX_LENGTH_OF_KEY + sizeof(char*) x 4)
          + SUM_OVER_ALL_HASH_KEYS(sizeof(char*) x 2)
          + ALIGN(LENGTH_OF_ROW+1, sizeof(char*))

     `ALIGN()' represents a round-up factor to cause the row length to
     be an exact multiple of the `char' pointer size.  `sizeof(char*)'
     is 4 on 32-bit machines and 8 on 64-bit machines.

As mentioned earlier, the `max_heap_table_size' system variable sets
the limit on the maximum size of `MEMORY' tables. To control the
maximum size for individual tables, set the session value of this
variable before creating each table. (Do not change the global
`max_heap_table_size' value unless you intend the value to be used for
`MEMORY' tables created by all clients.) The following example creates
two `MEMORY' tables, with a maximum size of 1MB and 2MB, respectively:

     mysql> SET max_heap_table_size = 1024*1024;
     Query OK, 0 rows affected (0.00 sec)

     mysql> CREATE TABLE t1 (id INT, UNIQUE(id)) ENGINE = MEMORY;
     Query OK, 0 rows affected (0.01 sec)

     mysql> SET max_heap_table_size = 1024*1024*2;
     Query OK, 0 rows affected (0.00 sec)

     mysql> CREATE TABLE t2 (id INT, UNIQUE(id)) ENGINE = MEMORY;
     Query OK, 0 rows affected (0.00 sec)

Both tables will revert to the server's global `max_heap_table_size'
value if the server restarts.

You can also specify a `MAX_ROWS' table option in `CREATE TABLE'
statements for `MEMORY' tables to provide a hint about the number of
rows you plan to store in them. This does not allow the table to grow
beyond the `max_heap_table_size' value, which still acts as a
constraint on maximum table size. For maximum flexibility in being able
to use `MAX_ROWS', set `max_heap_table_size' at least as high as the
value to which you want each `MEMORY' table to be able to grow.

*Additional resources*

   * A forum dedicated to the `MEMORY' storage engine is available at
     `http://forums.mysql.com/list.php?92'.


File: manual.info,  Node: example-storage-engine,  Next: federated-storage-engine,  Prev: memory-storage-engine,  Up: storage-engines

13.8 The `EXAMPLE' Storage Engine
=================================

The `EXAMPLE' storage engine is a stub engine that does nothing. Its
purpose is to serve as an example in the MySQL source code that
illustrates how to begin writing new storage engines. As such, it is
primarily of interest to developers.

To enable the `EXAMPLE' storage engine if you build MySQL from source,
invoke `configure' with the `--with-example-storage-engine' option.

To examine the source for the `EXAMPLE' engine, look in the
`storage/example' directory of a MySQL source distribution.

When you create an `EXAMPLE' table, the server creates a table format
file in the database directory. The file begins with the table name and
has an `.frm' extension. No other files are created. No data can be
stored into the table. Retrievals return an empty result.

     mysql> CREATE TABLE test (i INT) ENGINE = EXAMPLE;
     Query OK, 0 rows affected (0.78 sec)

     mysql> INSERT INTO test VALUES(1),(2),(3);
     ERROR 1031 (HY000): Table storage engine for 'test' doesn't »
                         have this option

     mysql> SELECT * FROM test;
     Empty set (0.31 sec)

The `EXAMPLE' storage engine does not support indexing.


File: manual.info,  Node: federated-storage-engine,  Next: archive-storage-engine,  Prev: example-storage-engine,  Up: storage-engines

13.9 The `FEDERATED' Storage Engine
===================================

* Menu:

* federated-description::        `FEDERATED' Storage Engine Overview
* federated-create::             How to Create `FEDERATED' Tables
* federated-usagenotes::         `FEDERATED' Storage Engine Notes and Tips
* federated-storage-engine-resources::  `FEDERATED' Storage Engine Resources

The `FEDERATED' storage engine enables data to be accessed from a
remote MySQL database on a local server without using replication or
cluster technology. When using a `FEDERATED' table, queries on the
local server are automatically executed on the remote (federated)
tables. No data is stored on the local tables.

To include the `FEDERATED' storage engine if you build MySQL from
source, invoke `configure' with the `--with-federated-storage-engine'
option.

Beginning with MySQL 5.1.26, the `FEDERATED' storage engine is not
enabled by default in the running server; to enable `FEDERATED', you
must start the MySQL server binary using the `--federated' option.

To examine the source for the `FEDERATED' engine, look in the
`storage/federated' directory of a MySQL source distribution.

MySQL Enterprise

MySQL Enterprise subscribers will find MySQL Knowledge Base articles
about the `FEDERATED' storage engine at FEDERATED Storage Engine
(https://kb.mysql.com/search.php?cat=search&category=272). Access to
the Knowledge Base collection of articles is one of the advantages of
subscribing to MySQL Enterprise. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: federated-description,  Next: federated-create,  Prev: federated-storage-engine,  Up: federated-storage-engine

13.9.1 `FEDERATED' Storage Engine Overview
------------------------------------------

When you create a table using one of the standard storage engines (such
as `MyISAM', `CSV' or `InnoDB'), the table consists of the table
definition and the associated data. When you create a `FEDERATED'
table, the table definition is the same, but the physical storage of
the data is handled on a remote server.

A `FEDERATED' table consists of two elements:

   * A _remote server_ with a database table, which in turn consists of
     the table definition (stored in the `.frm' file) and the
     associated table. The table type of the remote table may be any
     type supported by the remote `mysqld' server, including `MyISAM'
     or `InnoDB'.

   * A _local server_ with a database table, where the table definition
     matches that of the corresponding table on the remote server. The
     table definition is stored within the `.frm' file. However, there
     is no data file on the local server. Instead, the table definition
     includes a connection string that points to the remote table.

When executing queries and statements on a `FEDERATED' table on the
local server, the operations that would normally insert, update or
delete information from a local data file are instead sent to the remote
server for execution, where they update the data file on the remote
server or return matching rows from the remote server.

The basic structure of a `FEDERATED' table setup is shown in *Note
figure-se-federated-structure::.

FIGURE GOES HERE: `FEDERATED' table structure

When a client issues a SQL statement that refers to a `FEDERATED'
table, the flow of information between the local server (where the SQL
statement is executed) and the remote server (where the data is
physically stored) is as follows:

  1. The storage engine looks through each column that the `FEDERATED'
     table has and constructs an appropriate SQL statement that refers
     to the remote table.

  2. The statement is sent to the remote server using the MySQL client
     API.

  3. The remote server processes the statement and the the local server
     retrieves any result that the statement produces (an affected-rows
     count or a result set).

  4. If the statement produces a result set, each column is converted
     to internal storage engine format that the `FEDERATED' engine
     expects and can use to display the result to the client that
     issued the original statement.

The local server communicates with the remote server using MySQL client
C API functions. It invokes *Note `mysql_real_query()':
mysql-real-query. to send the statement. To read a result set, it uses
*Note `mysql_store_result()': mysql-store-result. and fetches rows one
at a time using *Note `mysql_fetch_row()': mysql-fetch-row.


File: manual.info,  Node: federated-create,  Next: federated-usagenotes,  Prev: federated-description,  Up: federated-storage-engine

13.9.2 How to Create `FEDERATED' Tables
---------------------------------------

* Menu:

* federated-create-connection::  Creating a `FEDERATED' Table Using `CONNECTION'
* federated-create-server::      Creating a `FEDERATED' Table Using `CREATE SERVER'

To create a `FEDERATED' table you should follow these steps:

  1. Create the table on the remote server. Alternatively, make a note
     of the table definition of an existing table, perhaps using the
     `SHOW CREATE TABLE' statement.

  2. Create the table on the local server with an identical table
     definition, but adding the connection information that links the
     local table to the remote table.

For example, you could create the following table on the remote server:

     CREATE TABLE test_table (
         id     INT(20) NOT NULL AUTO_INCREMENT,
         name   VARCHAR(32) NOT NULL DEFAULT '',
         other  INT(20) NOT NULL DEFAULT '0',
         PRIMARY KEY  (id),
         INDEX name (name),
         INDEX other_key (other)
     )
     ENGINE=MyISAM
     DEFAULT CHARSET=latin1;

To create the local table that will be federated to the remote table,
there are two options available. You can either create the local table
and specify the connection string (containing the server name, login,
password) to be used to connect to the remote table using the
`CONNECTION', or you can use an existing connection that you have
previously created using the `CREATE SERVER' statement.

*Note*:

When you create the local table it _must_ have an identical definition
to the remote table.


File: manual.info,  Node: federated-create-connection,  Next: federated-create-server,  Prev: federated-create,  Up: federated-create

13.9.2.1 Creating a `FEDERATED' Table Using `CONNECTION'
........................................................

To use the first method, you must specify the `CONNECTION' string after
the engine type in a `CREATE TABLE' statement. For example:

     CREATE TABLE federated_table (
         id     INT(20) NOT NULL AUTO_INCREMENT,
         name   VARCHAR(32) NOT NULL DEFAULT '',
         other  INT(20) NOT NULL DEFAULT '0',
         PRIMARY KEY  (id),
         INDEX name (name),
         INDEX other_key (other)
     )
     ENGINE=FEDERATED
     DEFAULT CHARSET=latin1
     CONNECTION='mysql://fed_user@remote_host:9306/federated/test_table';

*Note*:

`CONNECTION' replaces the `COMMENT' used in some previous versions of
MySQL.

The `CONNECTION' string contains the information required to connect to
the remote server containing the table that will be used to physically
store the data. The connection string specifies the server name, login
credentials, port number and database/table information. In the
example, the remote table is on the server `remote_host', using port
9306. The name and port number should match the hostname (or IP
address) and port number of the remote MySQL server instance you want
to use as your remote table.

The format the connection string is as follows:

     SCHEME://USER_NAME[:PASSWORD]@HOST_NAME[:PORT_NUM]/DB_NAME/TBL_NAME

Where:

   * SCHEME -- is a recognized connection protocol. Only `mysql' is
     supported as the SCHEME value at this point.

   * USER_NAME -- the username for the connection. This user must have
     been created on the remote server, and must have suitable
     privileges to perform the required actions (`SELECT', `INSERT',
     `UPDATE', and so forth) on the remote table.

   * PASSWORD -- (optional) the corresponding password for `username'.

   * HOST_NAME -- the hostname or IP address of the remote server.

   * PORT_NUM -- (optional) the port number for the remote server. The
     default is 3306.

   * DB_NAME -- the name of the database holding the remote table.

   * TBL_NAME -- the name of the remote table. The name of the local
     and the remote table do not have to match.

Sample connection strings:

     CONNECTION='mysql://username:password@hostname:port/database/tablename'
     CONNECTION='mysql://username@hostname/database/tablename'
     CONNECTION='mysql://username:password@hostname/database/tablename'


File: manual.info,  Node: federated-create-server,  Prev: federated-create-connection,  Up: federated-create

13.9.2.2 Creating a `FEDERATED' Table Using `CREATE SERVER'
...........................................................

If you are creating a number of `FEDERATED' tables on the same server,
or if you want to simplify the process of creating `FEDERATED' tables,
you can use the `CREATE SERVER' statement to define the server
connection parameters, just as you would with the `CONNECTION' string.

The format of the `CREATE SERVER' statement is:

     CREATE SERVER
     SERVER_NAME
     FOREIGN DATA WRAPPER WRAPPER_NAME
     OPTIONS (OPTION [, OPTION] ...)

The SERVER_NAME is used in the connection string when creating a new
`FEDERATED' table.

For example, to create a server connection identical to the
`CONNECTION' string:

     CONNECTION='mysql://fed_user@remote_host:9306/federated/test_table';

You would use the following statement:

     CREATE SERVER fedlink
     FOREIGN DATA WRAPPER mysql
     OPTIONS (USER 'fed_user', HOST 'remote_host', PORT 9306, DATABASE 'federated');

To create a `FEDERATED' table that uses this connection, you still use
the `CONNECTION' keyword, but specify the name you used in the `CREATE
SERVER' statement.

     CREATE TABLE test_table (
         id     INT(20) NOT NULL AUTO_INCREMENT,
         name   VARCHAR(32) NOT NULL DEFAULT '',
         other  INT(20) NOT NULL DEFAULT '0',
         PRIMARY KEY  (id),
         INDEX name (name),
         INDEX other_key (other)
     )
     ENGINE=FEDERATED
     DEFAULT CHARSET=latin1
     CONNECTION='fedlink/test_table';

The connection name in this example contains the name of the connection
(`fedlink') and the name of the table (`test_table') to link to,
separated by a slash. If you specify only the connection name without a
table name, the table name of the local table is used instead.

For more information on `CREATE SERVER', see *Note create-server::.

The `CREATE SERVER' statement accepts the same arguments as the
`CONNECTION' string. The `CREATE SERVER' statement updates the rows in
the `mysql.servers' table. See the following table for information on
the correspondence between parameters in a connection string, options
in the `CREATE SERVER' statement, and the columns in the
`mysql.servers' table. For reference, the format of the `CONNECTION'
string is as follows:

     SCHEME://USER_NAME[:PASSWORD]@HOST_NAME[:PORT_NUM]/DB_NAME/TBL_NAME

Description        `CONNECTION'       `CREATE SERVER'    `mysql.servers'
                   string             option             column
Connection scheme  SCHEME             `wrapper_name'     `Wrapper'
Remote user        USER_NAME          `USER'             `Username'
Remote password    PASSWORD           `PASSWORD'         `Password'
Remote host        HOST_NAME          `HOST'             `Host'
Remote port        PORT_NUM           `PORT'             `Port'
Remote database    DB_NAME            `DATABASE'         `Db'


File: manual.info,  Node: federated-usagenotes,  Next: federated-storage-engine-resources,  Prev: federated-create,  Up: federated-storage-engine

13.9.3 `FEDERATED' Storage Engine Notes and Tips
------------------------------------------------

You should be aware of the following points when using the `FEDERATED'
storage engine:

   * `FEDERATED' tables may be replicated to other slaves, but you must
     ensure that the slave servers are able to use the user/password
     combination that is defined in the `CONNECTION' string (or the row
     in the `mysql.servers' table) to connect to the remote server.

The following items indicate features that the `FEDERATED' storage
engine does and does not support:

   * The remote server must be a MySQL server. Support by `FEDERATED'
     for other database engines may be added in the future.

   * The remote table that a `FEDERATED' table points to _must_ exist
     before you try to access the table through the `FEDERATED' table.

   * It is possible for one `FEDERATED' table to point to another, but
     you must be careful not to create a loop.

   * A `FEDERATED' table does not support indexes per se. Because
     access to the table is handled remotely, it is the remote table
     that supports the indexes. Care should be taken when creating a
     `FEDERATED' table since the index definition from an equivalent
     `MyISAM' or other table may not be supported.  For example,
     creating a `FEDERATED' table with an index prefix on `VARCHAR',
     `TEXT' or `BLOB' columns will fail. The following definition in
     `MyISAM' is valid:

          CREATE TABLE `T1`(`A` VARCHAR(100),UNIQUE KEY(`A`(30))) ENGINE=MYISAM;

     The key prefix in this example is incompatible with the
     `FEDERATED' engine, and the equivalent statement will fail:

          CREATE TABLE `T1`(`A` VARCHAR(100),UNIQUE KEY(`A`(30))) ENGINE=FEDERATED
            CONNECTION='MYSQL://127.0.0.1:3306/TEST/T1';

     If possible, you should try to separate the column and index
     definition when creating tables on both the remote server and the
     local server to avoid these index issues.

   * Internally, the implementation uses `SELECT', `INSERT', `UPDATE',
     and `DELETE', but not `HANDLER'.

   * The `FEDERATED' storage engine supports `SELECT', `INSERT',
     `UPDATE', `DELETE', `TRUNCATE', and indexes. It does not support
     `ALTER TABLE', or any Data Definition Language statements that
     directly affect the structure of the table, other than `DROP
     TABLE'. The current implementation does not use prepared
     statements.

   * `FEDERATED' accepts `INSERT ... ON DUPLICATE KEY UPDATE'
     statements, but if a duplicate-key violation occurs, the statement
     fails with an error.

   * Performance on a `FEDERATED' table when performing bulk inserts
     (for example, on a `INSERT INTO ... SELECT ...' statement) is
     slower than with other table types because each selected row is
     treated as an individual `INSERT' statement on the `FEDERATED'
     table.

   * Transactions are not supported.

   * Before MySQL 5.1.21, for a multiple-row insert into a `FEDERATED'
     table that refers to a remote transactional table, if the insert
     failed for a row due to constraint failure, the remote table would
     contain a partial commit (the rows preceding the failed one)
     instead of rolling back the statement completely. This occurred
     because the rows were treated as individual inserts.

     As of MySQL 5.1.21, `FEDERATED' performs bulk-insert handling such
     that multiple rows are sent to the remote table in a batch. This
     provides a performance improvement and enables the the remote
     table to perform improvement. Also, if the remote table is
     transactional, it enables the remote storage engine to perform
     statement rollback properly should an error occur. This capability
     has the following limitations:

        * The size of the insert cannot exceed the maximum packet size
          between servers. If the insert exceeds this size, it is
          broken into multiple packets and the rollback problem can
          occur.

        * Bulk-insert handling does not occur for `INSERT ... ON
          DUPLICATE KEY UPDATE'.

   * There is no way for the `FEDERATED' engine to know if the remote
     table has changed. The reason for this is that this table must
     work like a data file that would never be written to by anything
     other than the database system. The integrity of the data in the
     local table could be breached if there was any change to the
     remote database.

   * When using a `CONNECTION' string, you cannot use an '@' character
     in the password. You can get round this limitation by using the
     `CREATE SERVER' statement to create a server connection.

   * The `INSERT_ID' and `TIMESTAMP' options are not propagated to the
     data provider.

   * Any `DROP TABLE' statement issued against a `FEDERATED' table
     drops only the local table, not the remote table.

   * `FEDERATED' tables do not work with the query cache.

   * User-defined partitioning is not supported for `FEDERATED' tables.
     Beginning with MySQL 5.1.15, it is no longer possible to create
     such tables at all.

Some of these limitations may be lifted in future versions of the
`FEDERATED' handler.


File: manual.info,  Node: federated-storage-engine-resources,  Prev: federated-usagenotes,  Up: federated-storage-engine

13.9.4 `FEDERATED' Storage Engine Resources
-------------------------------------------

The following additional resources are available for the `FEDERATED'
storage engine:

   * A forum dedicated to the `FEDERATED' storage engine is available at
     `http://forums.mysql.com/list.php?105'.


File: manual.info,  Node: archive-storage-engine,  Next: csv-storage-engine,  Prev: federated-storage-engine,  Up: storage-engines

13.10 The `ARCHIVE' Storage Engine
==================================

The `ARCHIVE' storage engine is used for storing large amounts of data
without indexes in a very small footprint.

The `ARCHIVE' storage engine is included in MySQL binary distributions.
To enable this storage engine if you build MySQL from source, invoke
`configure' with the `--with-archive-storage-engine' option.

To examine the source for the `ARCHIVE' engine, look in the
`storage/archive' directory of a MySQL source distribution.

You can check whether the `ARCHIVE' storage engine is available with
the `SHOW ENGINES' statement.

When you create an `ARCHIVE' table, the server creates a table format
file in the database directory. The file begins with the table name and
has an `.frm' extension. The storage engine creates other files, all
having names beginning with the table name. The data and metadata files
have extensions of `.ARZ' and `.ARM', respectively. An `.ARN' file may
appear during optimization operations.

The `ARCHIVE' engine supports `INSERT' and `SELECT', but not `DELETE',
`REPLACE', or `UPDATE'. It does support `ORDER BY' operations, `BLOB'
columns, and basically all but spatial data types (see *Note
mysql-spatial-datatypes::). The `ARCHIVE' engine uses row-level locking.

As of MySQL 5.1.6, the `ARCHIVE' engine supports the `AUTO_INCREMENT'
column attribute. The `AUTO_INCREMENT' column can have either a unique
or non-unique index. Attempting to create an index on any other column
results in an error. The `ARCHIVE' engine also supports the
`AUTO_INCREMENT' table option in `CREATE TABLE' and `ALTER TABLE'
statements to specify the initial sequence value for a new table or
reset the sequence value for an existing table, respectively.

As of MySQL 5.1.6, the `ARCHIVE' engine ignores `BLOB' columns if they
are not requested and scans past them while reading. Formerly, the
following two statements had the same cost, but as of 5.1.6, the second
is much more efficient than the first:

     SELECT a, b, blob_col FROM archive_table;
     SELECT a, b FROM archive_table;

*Storage:* Rows are compressed as they are inserted. The `ARCHIVE'
engine uses `zlib' lossless data compression (see
`http://www.zlib.net/'). You can use `OPTIMIZE TABLE' to analyze the
table and pack it into a smaller format (for a reason to use `OPTIMIZE
TABLE', see later in this section). The engine also supports `CHECK
TABLE'. There are several types of insertions that are used:

   * An `INSERT' statement just pushes rows into a compression buffer,
     and that buffer flushes as necessary. The insertion into the
     buffer is protected by a lock. A `SELECT' forces a flush to occur,
     unless the only insertions that have come in were `INSERT DELAYED'
     (those flush as necessary). See *Note insert-delayed::.

   * A bulk insert is visible only after it completes, unless other
     inserts occur at the same time, in which case it can be seen
     partially. A `SELECT' never causes a flush of a bulk insert unless
     a normal insert occurs while it is loading.

*Retrieval*: On retrieval, rows are uncompressed on demand; there is no
row cache. A `SELECT' operation performs a complete table scan: When a
`SELECT' occurs, it finds out how many rows are currently available and
reads that number of rows.  `SELECT' is performed as a consistent read.
Note that lots of `SELECT' statements during insertion can deteriorate
the compression, unless only bulk or delayed inserts are used. To
achieve better compression, you can use `OPTIMIZE TABLE' or `REPAIR
TABLE'. The number of rows in `ARCHIVE' tables reported by `SHOW TABLE
STATUS' is always accurate. See *Note optimize-table::, *Note
repair-table::, and *Note show-table-status::.

*Additional resources*

   * A forum dedicated to the `ARCHIVE' storage engine is available at
     `http://forums.mysql.com/list.php?112'.


File: manual.info,  Node: csv-storage-engine,  Next: blackhole-storage-engine,  Prev: archive-storage-engine,  Up: storage-engines

13.11 The `CSV' Storage Engine
==============================

* Menu:

* se-csv-repair::                Repairing and Checking CSV Tables
* se-csv-limitations::           CSV Limitations

The `CSV' storage engine stores data in text files using
comma-separated values format.

To enable the `CSV' storage engine if you build MySQL from source,
invoke `configure' with the `--with-csv-storage-engine' option.

To examine the source for the `CSV' engine, look in the `storage/csv'
directory of a MySQL source distribution.

When you create a `CSV' table, the server creates a table format file
in the database directory. The file begins with the table name and has
an `.frm' extension. The storage engine also creates a data file. Its
name begins with the table name and has a `.CSV' extension. The data
file is a plain text file. When you store data into the table, the
storage engine saves it into the data file in comma-separated values
format.

     mysql> CREATE TABLE test (i INT NOT NULL, c CHAR(10) NOT NULL)
         -> ENGINE = CSV;
     Query OK, 0 rows affected (0.12 sec)

     mysql> INSERT INTO test VALUES(1,'record one'),(2,'record two');
     Query OK, 2 rows affected (0.00 sec)
     Records: 2  Duplicates: 0  Warnings: 0

     mysql> SELECT * FROM test;
     +------+------------+
     | i    | c          |
     +------+------------+
     |    1 | record one |
     |    2 | record two |
     +------+------------+
     2 rows in set (0.00 sec)

Starting with MySQL 5.1.9, creating a CSV table also creates a
corresponding Meta-file that stores the state of the table and the
number of rows that exist in the table. The name of this file is the
same as the name of the table with the extension `CSM'.

If you examine the `test.CSV' file in the database directory created by
executing the preceding statements, its contents should look like this:

     "1","record one"
     "2","record two"

This format can be read, and even written, by spreadsheet applications
such as Microsoft Excel or StarOffice Calc.


File: manual.info,  Node: se-csv-repair,  Next: se-csv-limitations,  Prev: csv-storage-engine,  Up: csv-storage-engine

13.11.1 Repairing and Checking CSV Tables
-----------------------------------------

*Functionality introduced in version 5.1.9*

The CSV storage engines supports the `CHECK' and `REPAIR' commands to
verify and if possible repair a damaged CSV table.

When running the `CHECK' command, the CSV file will be checked for
validity by looking for the correct field separators, escaped fields
(matching quotes and/or missing quotes), the correct number of fields
compared to the table definition and the existence of a corresponding
CSV metafile. The first invalid row discovered will report an error.
Checking a valid table produces output like that shown below:

     mysql> check table csvtest;
     +--------------+-------+----------+----------+
     | Table        | Op    | Msg_type | Msg_text |
     +--------------+-------+----------+----------+
     | test.csvtest | check | status   | OK       |
     +--------------+-------+----------+----------+
     1 row in set (0.00 sec)

A check on a corrupted table returns a fault:

     mysql> check table csvtest;
     +--------------+-------+----------+----------+
     | Table        | Op    | Msg_type | Msg_text |
     +--------------+-------+----------+----------+
     | test.csvtest | check | error    | Corrupt  |
     +--------------+-------+----------+----------+
     1 row in set (0.01 sec)

If the check fails, the table is marked as crashed (corrupt). Once a
table has been marked as corrupt, it is automatically repaired when you
next run `CHECK' or execute a `SELECT' statement. The corresponding
corrupt status and new status will be displayed when running `CHECK':

     mysql> check table csvtest;
     +--------------+-------+----------+----------------------------+
     | Table        | Op    | Msg_type | Msg_text                   |
     +--------------+-------+----------+----------------------------+
     | test.csvtest | check | warning  | Table is marked as crashed |
     | test.csvtest | check | status   | OK                         |
     +--------------+-------+----------+----------------------------+
     2 rows in set (0.08 sec)

To repair a table you can use `REPAIR', this copies as many valid rows
from the existing CSV data as possible, and then replaces the existing
CSV file with the recovered rows.  Any rows beyond the corrupted data
are lost.

     mysql> repair table csvtest;
     +--------------+--------+----------+----------+
     | Table        | Op     | Msg_type | Msg_text |
     +--------------+--------+----------+----------+
     | test.csvtest | repair | status   | OK       |
     +--------------+--------+----------+----------+
     1 row in set (0.02 sec)

*Warning*:

Note that during repair, only the rows from the CSV file up to the
first damaged row are copied to the new table. All other rows from the
first damaged row to the end of the table are removed, even valid rows.


File: manual.info,  Node: se-csv-limitations,  Prev: se-csv-repair,  Up: csv-storage-engine

13.11.2 CSV Limitations
-----------------------

*Important*:

The `CSV' storage engine does not support indexing.

Partitioning is not supported for tables using the `CSV' storage
engine. Beginning with MySQL 5.1.12, it is no longer possible to create
partitioned `CSV' tables. (See Bug#19307 (http://bugs.mysql.com/19307))

Beginning with MySQL 5.1.23, tables using the `CSV' storage engine can
no longer be created with `NULL' columns. However, for backwards
compatibility, you can continue to use such tables that were created in
previous MySQL releases. (Bug#32050 (http://bugs.mysql.com/32050))


File: manual.info,  Node: blackhole-storage-engine,  Prev: csv-storage-engine,  Up: storage-engines

13.12 The `BLACKHOLE' Storage Engine
====================================

The `BLACKHOLE' storage engine acts as a `black hole' that accepts data
but throws it away and does not store it. Retrievals always return an
empty result:

     mysql> CREATE TABLE test(i INT, c CHAR(10)) ENGINE = BLACKHOLE;
     Query OK, 0 rows affected (0.03 sec)

     mysql> INSERT INTO test VALUES(1,'record one'),(2,'record two');
     Query OK, 2 rows affected (0.00 sec)
     Records: 2  Duplicates: 0  Warnings: 0

     mysql> SELECT * FROM test;
     Empty set (0.00 sec)

To enable the `BLACKHOLE' storage engine if you build MySQL from
source, invoke `configure' with the `--with-blackhole-storage-engine'
option.

To examine the source for the `BLACKHOLE' engine, look in the `sql'
directory of a MySQL source distribution.

When you create a `BLACKHOLE' table, the server creates a table format
file in the database directory. The file begins with the table name and
has an `.frm' extension. There are no other files associated with the
table.

The `BLACKHOLE' storage engine supports all kinds of indexes. That is,
you can include index declarations in the table definition.

You can check whether the `BLACKHOLE' storage engine is available with
the `SHOW ENGINES' statement.

Inserts into a `BLACKHOLE' table do not store any data, but if the
binary log is enabled, the SQL statements are logged (and replicated to
slave servers). This can be useful as a repeater or filter mechanism.
For example, suppose that your application requires slave-side
filtering rules, but transferring all binary log data to the slave
first results in too much traffic.  In such a case, it is possible to
set up on the master host a `dummy' slave process whose default storage
engine is `BLACKHOLE', depicted as follows:

Replication using `BLACKHOLE' for filtering

The master writes to its binary log. The `dummy' `mysqld' process acts
as a slave, applying the desired combination of `replicate-do-*' and
`replicate-ignore-*' rules, and writes a new, filtered binary log of
its own. (See *Note replication-options::.) This filtered log is
provided to the slave.

The dummy process does not actually store any data, so there is little
processing overhead incurred by running the additional `mysqld' process
on the replication master host.  This type of setup can be repeated
with additional replication slaves.

`INSERT' triggers for `BLACKHOLE' tables work as expected. However,
because the `BLACKHOLE' table does not actually store any data,
`UPDATE' and `DELETE' triggers are not activated: The `FOR EACH ROW'
clause in the trigger definition does not apply because there are no
rows.

Other possible uses for the `BLACKHOLE' storage engine include:

   * Verification of dump file syntax.

   * Measurement of the overhead from binary logging, by comparing
     performance using `BLACKHOLE' with and without binary logging
     enabled.

   * `BLACKHOLE' is essentially a `no-op' storage engine, so it could
     be used for finding performance bottlenecks not related to the
     storage engine itself.

The `BLACKHOLE' storage engine does not support `INSERT DELAYED', `LOCK
TABLES', or `UNLOCK TABLES' statements prior to MySQL 5.1.19.

As of MySQL 5.1.4, the `BLACKHOLE' engine is transaction-aware, in the
sense that committed transactions are written to the binary log and
rolled-back transactions are not.


File: manual.info,  Node: ha-overview,  Next: ha-vm,  Prev: storage-engines,  Up: Top

14 High Availability and Scalability
************************************

* Menu:

* ha-drbd::                      Using MySQL with DRBD for High Availability
* ha-heartbeat::                 Using Linux HA Heartbeat

When using MySQL you may need to ensure the availability or scalability
of your MySQL installation. Availability refers to the ability to cope
with, and if necessary recover from, failures on the host, including
failures of MySQL, the operating system, or the hardware. Scalability
refers to the ability to spread the load of your application queries
across multiple MySQL servers. As your application and usage increases,
you may need to spread the queries for the application across multiple
servers to improve response times.

There are a number of solutions available for solving issues of
availability and scalability. The two primary solutions supported by
MySQL are MySQL Replication and MySQL Cluster. Further options are
available using third-party solutions such as DRBD (Distributed
Replicated Block Device) and Heartbeat, and more complex scenarios can
be solved through a combination of these technologies. These tools work
in different ways:

   * _MySQL Replication_ enables statements and data from one MySQL
     server instance to be replicated to another MySQL server instance.
     Without using more complex setups, data can only be replicated
     from a single master server to any number of slaves. The
     replication is asynchronous, so the synchronization does not take
     place in real time, and there is no guarantee that data from the
     master will have been replicated to the slaves.

        * *Advantages*

             * MySQL Replication is available on all platforms
               supported by MySQL, and since it isn't operating
               system-specific it can operate across different
               platforms.

             * Replication is asynchronous and can be stopped and
               restarted at any time, making it suitable for
               replicating over slower links, partial links and even
               across geographical boundaries.

             * Data can be replicated from one master to any number of
               slaves, making replication suitable in environments with
               heavy reads, but light writes (for example, many web
               applications), by spreading the load across multiple
               slaves.

        * *Disadvantages*

             * Data can only be written to the master. In advanced
               configurations, though, you can set up a multiple-master
               configuration where the data is replicated around a ring
               configuration.

             * There is no guarantee that data on master and slaves
               will be consistent at a given point in time. Because
               replication is asynchronous there may be a small delay
               between data being written to the master and it being
               available on the slaves. This can cause problems in
               applications where a write to the master must be
               available for a read on the slaves (for example a web
               application).

        * *Recommended uses*

             * Scale-out solutions that require a large number of reads
               but fewer writes (for example, web serving).

             * Logging/data analysis of live data. By replicating live
               data to a slave you can perform queries on the slave
               without affecting the operation of the master.

             * Online backup (availability), where you need an active
               copy of the data available. You need to combine this
               with other tools, such as custom scripts or Heartbeat.
               However, because of the asynchronous architecture, the
               data may be incomplete.

             * Offline backup. You can use replication to keep a copy
               of the data. By replicating the data to a slave, you
               take the slave down and get a reliable snapshot of the
               data (without MySQL running), then restart MySQL and
               replication to catch up. The master (and any other
               slaves) can be kept running during this period.

     For information on setting up and configuring replication, see
     *Note replication::.

   * _MySQL Cluster_ is a synchronous solution that enables multiple
     MySQL instances to share database information. Unlike replication,
     data in a cluster can be read from or written to any node within
     the cluster, and information will be distributed to the other
     nodes.

        * *Advantages*

             * Offers multiple read and write nodes for data storage.

             * Provides automatic failover between nodes. Only
               transaction information for the active node being used
               is lost in the event of a failure.

             * Data on nodes is instantaneously distributed to the
               other data nodes.

        * *Disadvantages*

             * Available on a limited range of platforms.

             * Nodes within a cluster should be connected via a LAN;
               geographically separate nodes are not supported.
               However, you can replicate from one cluster to another
               using MySQL Replication, although the replication in
               this case is still asynchronous.

        * *Recommended uses*

             * Applications that need very high availability, such as
               telecoms and banking.

             * Applications that require an equal or higher number of
               writes compared to reads.

     For information on MySQL Cluster, see *Note mysql-cluster::.

   * _DRBD (Distributed Replicated Block Device)_ is a solution from
     Linbit supported only on Linux. DRBD creates a virtual block
     device (which is associated with an underlying physical block
     device) that can be replicated from the primary server to a
     secondary server. You create a filesystem on the virtual block
     device, and this information is then replicated, at the block
     level, to the secondary server.

     Because the block device, not the data you are storing on it, is
     being replicated the validity of the information is more reliable
     than with data-only replication solutions. DRBD can also ensure
     data integrity by only returning from a write operation on the
     primary server when the data has been written to the underlying
     physical block device on both the primary and secondary servers.

        * *Advantages*

             * Provides high availability and data integrity across two
               servers in the event of hardware or system failure.

             * Can ensure data integrity by enforcing write consistency
               on the primary and secondary nodes.

        * *Disadvantages*

             * Only provides a method for duplicating data across the
               nodes. Secondary nodes cannot use the DRBD device while
               data is being replicated, and so the MySQL on the
               secondary node cannot be simultaneously active.

             * Can not be used to scale performance, since you can not
               redirect reads to the secondary node.

        * *Recommended uses*

             * High availability situations where concurrent access to
               the data is not required, but instant access to the
               active data in the event of a system or hardware failure
               is required.

     For information on configuring DRBD and configuring MySQL for use
     with a DRBD device, see *Note ha-drbd::.

   * _`memcached'_ is a simple, yet highly-scalable key-based cache
     that stores data and objects wherever dedicated or spare RAM is
     available for very quick access by applications. You use
     `memcached' in combination with your application and MySQL to
     reduce the number of reads from the database.

     When writing your application, you first try to load the data from
     the `memcached' cache, if the data you are looking for cannot be
     found, you then load the data from the MySQL database as normal,
     and populate the cache with the information that you loaded.
     Because `memcached' can be used to store entire objects that might
     normally consist of multiple table lookups and aggregations, you
     can significantly increase the speed of your application because
     the requirement to load data directly from the database is reduced
     or even eliminated. Because the cache is entirely in RAM, the
     response time is very fast, and the information can be distributed
     among many servers to make the best use of any spare RAM capacity.

        * *Advantages*

             * Very fast, RAM based, cache.

             * Reduces load on the MySQL server, allowing MySQL to
               concentrate on persistent storage and data writes.

             * Highly distributable and scalable, allowing multiple
               servers to be part of the cache group.

             * Highly portable - the `memcached' interface is supported
               by many languages and systems, including Perl, Python,
               PHP, Ruby, Java and the MySQL server.

        * *Disadvantages*

             * Data is not persistent - you should only use the cache
               to store information that can otherwise be loaded from a
               MySQL database.

             * Fault tolerance is implied, rather than explicit. If a
               `memcached' node fails then your application must be
               capable of loading the data from MySQL and updating the
               cache.

        * *Recommended uses*

             * High scalability situations where you have a very high
               number of reads, particularly of complex data objects
               that can easily be cached in the final, usable, form
               directly within the cache.

     For information on installing, configuring and using `memcached',
     including using the many APIs available for communicating with
     `memcached', see *Note ha-memcached::.

   * _Heartbeat_ is a software solution for Linux.  It is not a data
     replication or synchronization solution, but a solution for
     monitoring servers and switching active MySQL servers
     automatically in the event of failure. Heartbeat needs to be
     combined with MySQL Replication or DRBD to provide automatic
     failover.

     For more information on configuring Heartbeat for use with MySQL
     and DRBD, see *Note ha-heartbeat::.

The information and suitability of the various technologies and
different scenarios is summarized in the table below.

Requirements   MySQL        MySQL        MySQL        MySQL        MySQL +
               Replication  Replication  Heartbeat +  Cluster      `memcached'
                            + Heartbeat  DRBD                      
*Availability*                                                     
Automated IP   No           Yes          Yes          No           No
failover                                                           
Automated      No           No           Yes          Yes          No
database                                                           
failover                                                           
Typical        User/script-dependentVaries       < 30 seconds < 3 seconds  App
failover time                                                      dependent
Automatic      No           No           Yes          Yes          No
resynchronization                                                    
of data                                                            
Geographic     Yes          Yes          Yes, when    Yes, when    No
redundancy                               combined     combined     
support                                  with MySQL   with MySQL   
                                         Replication  Replication  
*Scalability*                                                      
Built-in load  No           No           No           Yes          Yes
balancing                                                          
Supports       Yes          Yes          Yes, when    Yes          Yes
Read-intensive                           combined                  
applications                             with MySQL                
                                         Replication               
Supports       No           No           Yes          Yes          No
Write-intensive                                                    
applications                                                       
Maximum        One master,  One master,  One active   255          Unlimited
number of      multiple     multiple     (primary),                
nodes per      slaves       slaves       one passive               
group                                    (secondary)               
                                         node                      
Maximum        Unlimited    Unlimited    One          Unlimited    Unlimited
number of      (reads only) (reads only) (failover    (reads only) 
slaves                                   only)                     


File: manual.info,  Node: ha-drbd,  Next: ha-heartbeat,  Prev: ha-overview,  Up: ha-overview

14.1 Using MySQL with DRBD for High Availability
================================================

* Menu:

* ha-drbd-install::              Configuring the DRBD Environment
* ha-drbd-install-mysql::        Configuring MySQL for DRBD
* ha-drbd-performance::          Optimizing Performance and Reliability

The Distributed Replicated Block Device (DRBD) is a Linux Kernel module
that constitutes a distributed storage system. You can use DRBD to
share block devices between Linux servers and, in turn, share
filesystems and data.

DRBD implements a block device which can be used for storage and which
is replicated from a primary server to one or more secondary servers.
The distributed block device is handled by the DRBD service. Writes to
the DRBD block device are distributed among the servers. Each DRBD
service writes the information from the DRBD block device to a local
physical block device (hard disk).

On the primary, for example, the data writes are written both to the
underlying physical block device and distributed to the secondary DRBD
services. On the secondary, the writes received through DRBD and
written to the local physical block device. On both the primary and the
secondary, reads from the DRBD block device are handled by the
underlying physical block device. The information is shared between the
primary DRBD server and the secondary DRBD server synchronously and at
a block level, and this means that DRBD can be used in
high-availability solutions where you need failover support.

FIGURE GOES HERE: DRBD Architecture

When used with MySQL, DRBD can be used to ensure availability in the
event of a failure. MySQL is configured to store information on the
DRBD block device, with one server acting as the primary and a second
machine available to operate as an immediate replacement in the event
of a failure.

For automatic failover support you can combine DRBD with the Linux
Heartbeat project, which will manage the interfaces on the two servers
and automatically configure the secondary (passive) server to replace
the primary (active) server in the event of a failure.  You can also
combine DRBD with MySQL Replication to provide both failover and
scalability within your MySQL environment.

For information on how to configure DRBD and MySQL, including Heartbeat
support, see *Note ha-drbd-install::.

An FAQ for using DRBD and MySQL is available. See *Note
faqs-mysql-drbd-heartbeat::.

*Note*:

Because DRBD is a Linux Kernel module it is currently not supported on
platforms other than Linux.


File: manual.info,  Node: ha-drbd-install,  Next: ha-drbd-install-mysql,  Prev: ha-drbd,  Up: ha-drbd

14.1.1 Configuring the DRBD Environment
---------------------------------------

* Menu:

* ha-drbd-install-os::           Setting Up the OS for DRBD
* ha-drbd-install-drbd::         Installing and Configuring DRBD
* ha-drbd-install-drbd-primary::  Setting Up a DRBD Primary Node
* ha-drbd-install-drbd-secondary::  Setting Up a DRBD Secondary Node
* ha-drbd-install-drbd-using::   Monitoring and Managing Your DRBD Device
* ha-drbd-install-drbd-othercfg::  Additional DRBD Configuration Options

To set up DRBD, MySQL and Heartbeat you need to follow a number of
steps that affect the operating system, DRBD and your MySQL
installation.

Before starting the installation process, you should be aware of the
following information, terms and requirements on using DRBD:

   * DRBD is a solution for enabling high-availability, and therefore
     you need to ensure that the two machines within your DRBD setup
     are as identically configured as possible so that the secondary
     machine can act as a direct replacement for the primary machine in
     the event of system failure.

   * DRBD works through two (or more) servers, each called a _node_

   * The node that contains the primary data, has read/write access to
     the data, and in an HA environment is the currently active node is
     called the _primary_.

   * The server to which the data is replicated is referred as
     _secondary_.

   * A collection of nodes that are sharing information are referred to
     as a _DRBD cluster_.

   * For DRBD to operate you must have a block device on which the
     information can be stored on _each_ DRBD node. The _lower level_
     block device can be a physical disk partition, a partition from a
     volume group or RAID device or any other block device.

     Typically you use a spare partition on which the physical data
     will be stored . On the primary node, this disk will hold the raw
     data that you want replicated. On the secondary nodes, the disk
     will hold the data replicated to the secondary server by the DRBD
     service. Ideally, the size of the partition on the two DRBD
     servers should be identical, but this is not necessary as long as
     there is enough space to hold the data that you want distributed
     between the two servers.

   * For the distribution of data to work, DRBD is used to create a
     logical block device that uses the lower level block device for
     the actual storage of information. To store information on the
     distributed device, a filesystem is created on the DRBD logical
     block device.

   * When used with MySQL, once the filesystem has been created, you
     move the MySQL data directory (including InnoDB data files and
     binary logs) to the new filesystem.

   * When you set up the secondary DRBD server, you set up the physical
     block device and the DRBD logical block device that will store the
     data. The block device data is then copied from the primary to the
     secondary server.

The overview for the installation and configuration sequence is as
follows:

  1. First you need to set up your operating system and environment.
     This includes setting the correct hostname, updating the system
     and preparing the available packages and software required by
     DRBD, and configuring a physical block device to be used with the
     DRBD block device. See *Note ha-drbd-install-os::.

  2. Installing DRBD requires installing or compiling the DRBD source
     code and then configuring the DRBD service to set up the block
     devices that will be shared. See *Note ha-drbd-install-drbd::.

  3. Once DRBD has been configured, you must alter the configuration
     and storage location of the MySQL data. See *Note
     ha-drbd-install-mysql::.


File: manual.info,  Node: ha-drbd-install-os,  Next: ha-drbd-install-drbd,  Prev: ha-drbd-install,  Up: ha-drbd-install

14.1.1.1 Setting Up the OS for DRBD
...................................

To set your Linux environment for using DRBD there are a number of
system configuration steps that you must follow.

   * Make sure that the primary and secondary DRBD servers have the
     correct hostname, and that the hostnames are unique. You can
     verify this by using the `uname' command:

          $ uname -n
          drbd-one

     If the hostname is not set correctly then edit the appropriate
     file (usually `/etc/sysconfig/network', `/etc/hostname', or
     `/etc/conf.d/hostname') and set the name correctly.

   * Each DRBD node must have a unique IP address. Make sure that the
     IP address information is set correctly within the network
     configuration and that the hostname and IP address has been set
     correctly within the `/etc/hosts' file.

   * Although you can rely on the DNS or NIS system for host resolving,
     in the event of a major network failure these services may not be
     available. If possible, add the IP address and hostname of each
     DRBD node into the /etc/hosts file for each machine. This will
     ensure that the node information can always be determined even if
     the DNS/NIS servers are unavailable.

   * As a general rule, the faster your network connection the better.
     Because the block device data is exchanged over the network,
     everything that will be written to the local disk on the DRBD
     primary will also be written to the network for distribution to
     the DRBD secondary.

   * You must have a spare disk or disk partition that you can use as
     the physical storage location for the DRBD data that will be
     replicated. You do not have to have a complete disk available, a
     partition on an existing disk is acceptable.

     If the disk is unpartitioned, partition the disk using `fdisk',
     `cfdisk' or other partitioning solution.. Do not create a
     filesystem on the new partition.

     Remember that you must have a physical disk available for the
     storage of the replicated information on each DRBD node.  Ideally
     the partitions that will be used on each node should be of an
     identical size, although this is not strictly necessary. Do,
     however, ensure that the physical partition on the DRBD secondary
     is at least as big as the partitions on the DRBD primary node.

   * If possible, upgrade your system to the latest available Linux
     kernel for your distribution. Once the kernel has been installed,
     you must reboot to make the kernel active. To use DRBD you will
     also need to install the relevant kernel development and header
     files that are required for building kernel modules. Platform
     specification information for this is available later in this
     section.

Before you compile or install DRBD, you must make sure the following
tools and files are in place:

   * Kernel header files

   * Kernel source files

   * GCC Compiler

   * `glib 2'

   * `flex'

Here are some operating system specific tips for setting up your
installation:

   * *Tips for Red Hat (including CentOS and Fedora)*:

     Use `up2date' or `yum' to update and install the latest kernel and
     kernel header files:

          root-shell> up2date kernel-smp-devel kernel-smp

     Reboot. If you are going to build DRBD from source, then update
     your system with the required development packages

          root-shell> up2date glib-devel openssl-devel libgcrypt-devel glib2-devel \
          pkgconfig ncurses-devel rpm-build rpm-devel redhat-rpm-config gcc \
          gcc-c++ bison flex gnutls-devel lm_sensors-devel net-snmp-devel \
          python-devel bzip2-devel libselinux-devel perl-DBI

     If you are going to use the pre-built DRBD RPMs:

          root-shell> up2date gnutls lm_sensors net-snmp ncurses libgcrypt glib2 openssl glib

   * *Tips for Debian, Ubuntu, Kubuntu*:

     Use `apt-get' to install the kernel packages

          root-shell> apt-get install linux-headers linux-image-server

     If you are going to use the pre-built Debian packages for DRBD
     then you should not need any additional packages.

     If you want to build DRBD from source, you will need to use the
     following command to install the required components:

          root-shell> apt-get install devscripts flex bison build-essential \
          dpkg-dev kernel-package debconf-utils dpatch debhelper \
          libnet1-dev e2fslibs-dev libglib2.0-dev automake1.9 \
          libgnutls-dev libtool libltdl3 libltdl3-dev

   * *Tips for Gentoo*:

     Gentoo is a source based Linux distribution and therefore many of
     the source files and components that you will need are either
     already installed or will be installed automatically by `emerge'.

     To install DRBD 0.8.x, you must unmask the `sys-cluster/drbd'
     build by adding the following line to
     `/etc/portage/package.keywords':

          sys-cluster/drbd ~x86
          sys-cluster/drbd-kernel ~x86

     If your kernel does not already have the userspace to kernelspace
     linker enabled, then you will need to rebuild the kernel with this
     option. The best way to do this is to use `genkernel' with the
     `--menuconfig' option to select the option and then rebuild the
     kernel. For example, at the command line as `root':

          root-shell> genkernel --menuconfig all

     Then through the menu options, select `Device Drivers', `Connector
     - unified userspace <-> kernelspace linker' and finally press 'y'
     or 'space' to select the `Connector - unified userspace <->
     kernelspace linker' option.  Then exit the menu configuration. The
     kernel will be rebuilt and installed. If this is a new kernel,
     make sure you update your bootloader accordingly. Now reboot to
     enable the new kernel.

     You can now `emerge' DRBD 0.8.x into your Gentoo installation:

          root-shell> emerge drbd

     Once `drbd' has been downloaded and installed, you need to
     decompress and copy the default configuration file from
     `/usr/share/doc/drbd-8.0.7/drbd.conf.bz2' into `/etc/drbd.conf'.


File: manual.info,  Node: ha-drbd-install-drbd,  Next: ha-drbd-install-drbd-primary,  Prev: ha-drbd-install-os,  Up: ha-drbd-install

14.1.1.2 Installing and Configuring DRBD
........................................

To install DRBD you can choose either the pre-built binary installation
packages or you can use the source packages and build from source. If
you want to build from source you must have installed the source and
development packages.

If you are installing using a binary distribution then you must ensure
that the kernel version number of the binary package matches your
currently active kernel. You can use `uname' to find out this
information:

     $ uname -r
     2.6.20-gentoo-r6

To build from the sources, download the source `tar.gz' package,
extract the contents and then follow the instructions within the
`INSTALL' file.

Once DRBD has been built and installed, you need to edit the
`/etc/drbd.conf' file and then run a number of commands to build the
block device and set up the replication.

Although the steps below are split into those for the primary node and
the secondary node, it should be noted that the configuration files for
all nodes should be identical, and many of the same steps have to be
repeated on each node to enable the DRBD block device.


File: manual.info,  Node: ha-drbd-install-drbd-primary,  Next: ha-drbd-install-drbd-secondary,  Prev: ha-drbd-install-drbd,  Up: ha-drbd-install

14.1.1.3 Setting Up a DRBD Primary Node
.......................................

To set up a DRBD primary node you need to configure the DRBD service,
create the first DRBD block device and then create a filesystem on the
device so that you can store files and data.

The DRBD configuration file (`/etc/drbd.conf') defined a number of
parameters for your DRBD configuration, including the frequency of
updates and block sizes, security information and the definition of the
DRBD devices that you want to create.

The key elements to configure are the `on' sections which specify the
configuration of each node.

To follow the configuration, the sequence below shows only the changes
from the default `drbd.conf' file.  Configurations within the file can
be both global or tied to specific resource.

  1. Set the synchronization rate between the two nodes. This is the
     rate at which devices are synchronized in the background after a
     disk failure, device replacement or during the initial setup. You
     should keep this in check compared to the speed of your network
     connection. Gigabit Ethernet can support up to 125 MB/second,
     100Mbps Ethernet slightly less than a tenth of that (12MBps). If
     you are using a shared network connection, rather than a
     dedicated, then you should gauge accordingly.

     For more detailed information on synchronization, the effects of
     the synchronization rate and the effects on network performance,
     see *Note ha-drbd-performance-syncrate::.

     To set the synchronization rate, edit the `rate' setting within the
     `syncer' block:

          syncer {
              rate 10M;
          }

  2. Set up some basic authentication. DRBD supports a simple password
     hash exchange mechanism. This helps to ensure that only those
     hosts with the same shared secret are able to join the DRBD node
     group.

          cram-hmac-alg "sha1";
          shared-secret "SHARED-STRING";

  3. Now you must configure the host information. Remember that you
     must have the node information for the primary and secondary nodes
     in the `drbd.conf' file on each host. You need to configure the
     following information for each node:

        * `device' -- the path of the logical block device that will be
          created by DRBD.

        * `disk' -- the block device that will be used to store the
          data.

        * `address' -- the IP address and port number of the host that
          will hold this DRBD device.

        * `meta-disk' -- the location where the metadata about the DRBD
          device will be stored. You can set this to `internal' and DRBD
          will use the physical block device to store the information,
          by recording the metadata within the last sections of the
          disk. The exact size will depend on the size of the logical
          block device you have created, but it may involve up to 128MB.

     A sample configuration for our primary server might look like this:

          on drbd-one {
          device /dev/drbd0;
          disk /dev/hdd1;
          address 192.168.0.240:8888;
          meta-disk internal;
          }

     The `on' configuration block should be repeated for the secondary
     node (and any further) nodes:

          on drbd-two {
          device /dev/drbd0;
          disk /dev/hdd1;
          address 192.168.0.241:8888;
          meta-disk internal;
          }

     The IP address of each `on' block must match the IP address of the
     corresponding host. Do not set this value to the IP address of the
     corresponding primary or secondary in each case.

  4. Before starting the primary node, you should create the metadata
     for the devices:

          root-shell> drbdadm create-md all

  5. You are now ready to start DRBD:

          root-shell> /etc/init.d/drbd start

     DRBD should now start and initialize, creating the DRBD devices
     that you have configured.

  6. DRBD creates a standard block device - to make it usable, you must
     create a filesystem on the block device just as you would with any
     standard disk partition. Before you can create the filesystem, you
     must mark the new device as the primary device (i.e. where the
     data will be written and stored), and initialize the device.
     Because this is a destructive operation, you must specify the
     command line option to overwrite the raw data:

          root-shell> drbdadm -- --overwrite-data-of-peer primary all

     If you are using a version of DRBD 0.7.x or earlier, then you need
     to use a different command-line option:

          root-shell> drbdadm -- --do-what-I-say primary all

     Now create a filesystem using your chosen filesystem type:

          root-shell> mkfs.ext3 /dev/drbd0

  7. You can now mount the filesystem and if necessary copy files to
     the mount point:

          root-shell> mkdir /mnt/drbd
          root-shell> mount /dev/drbd0 /mnt/drbd
          root-shell> echo "DRBD Device" >/mnt/drbd/samplefile

Your primary node is now ready to use. You should now configure your
secondary node or nodes.


File: manual.info,  Node: ha-drbd-install-drbd-secondary,  Next: ha-drbd-install-drbd-using,  Prev: ha-drbd-install-drbd-primary,  Up: ha-drbd-install

14.1.1.4 Setting Up a DRBD Secondary Node
.........................................

The configuration process for setting up a secondary node is the same
as for the primary node, except that you do not have to create the
filesystem on the secondary node device, as this information will
automatically be transferred from the primary node.

To set up a secondary node:

  1. Copy the `/etc/drbd.conf' file from your primary node to your
     secondary node. It should already contain all the information and
     configuration that you need, since you had to specify the
     secondary node IP address and other information for the primary
     node configuration.

  2. Create the DRBD metadata on the underlying disk device:

          root-shell> drbdadm create-md all

  3. Start DRBD:

          root-shell> /etc/init.d/drbd start

Once DRBD has started, it will start the copy the data from the primary
node to the secondary node. Even with an empty filesystem this will
take some time, since DRBD is copying the block information from a
block device, not simply copying the filesystem data.

You can monitor the progress of the copy between the primary and
secondary nodes by viewing the output of `/proc/drbd':

     root-shell> cat /proc/drbd
     version: 8.0.4 (api:86/proto:86)
     SVN Revision: 2947 build by root@drbd-one, 2007-07-30 16:43:05
      0: cs:SyncSource st:Primary/Secondary ds:UpToDate/Inconsistent C r---
         ns:252284 nr:0 dw:0 dr:257280 al:0 bm:15 lo:0 pe:7 ua:157 ap:0
             [==>.................] sync'ed: 12.3% (1845088/2097152)K
             finish: 0:06:06 speed: 4,972 (4,580) K/sec
             resync: used:1/31 hits:15901 misses:16 starving:0 dirty:0 changed:16
             act_log: used:0/257 hits:0 misses:0 starving:0 dirty:0 changed:0


File: manual.info,  Node: ha-drbd-install-drbd-using,  Next: ha-drbd-install-drbd-othercfg,  Prev: ha-drbd-install-drbd-secondary,  Up: ha-drbd-install

14.1.1.5 Monitoring and Managing Your DRBD Device
.................................................

Once the primary and secondary machines are configured and
synchronized, you can get the status information about your DRBD device
by viewing the output from `/proc/drbd':

     root-shell> cat /proc/drbd
     version: 8.0.4 (api:86/proto:86)
     SVN Revision: 2947 build by root@drbd-one, 2007-07-30 16:43:05
      0: cs:Connected st:Primary/Secondary ds:UpToDate/UpToDate C r---
         ns:2175704 nr:0 dw:99192 dr:2076641 al:33 bm:128 lo:0 pe:0 ua:0 ap:0
             resync: used:0/31 hits:134841 misses:135 starving:0 dirty:0 changed:135
             act_log: used:0/257 hits:24765 misses:33 starving:0 dirty:0 changed:33

The first line provides the version/revision and build information.

The second line starts the detailed status information for an
individual resource. The individual field headings are as follows:

   * cs -- connection state

   * st -- node state (local/remote)

   * ld -- local data consistency

   * ds -- data consistency

   * ns -- network send

   * nr -- network receive

   * dw -- disk write

   * dr -- disk read

   * pe -- pending (waiting for ack)

   * ua -- unack'd (still need to send ack)

   * al -- access log write count

In the previous example, the information shown indicates that the nodes
are connected, the local node is the primary (because it is listed
first), and the local and remote data is up to date with each other.
The remainder of the information is statistical data about the device,
and the data exchanged that kept the information up to date.

For administration, the main command is `drbdadm'. There are a number
of commands supported by this tool the control the connectivity and
status of the DRBD devices.

The most common commands are those to set the primary/secondary status
of the local device. You can manually set this information for a number
of reasons, including when you want to check the physical status of the
secondary device (since you cannot mount a DRBD device in primary
mode), or when you are temporarily moving the responsibility of keeping
the data in check to a different machine (for example, during an
upgrade or physical move of the normal primary node). You can set state
of all local device to be the primary using this command:

     root-shell> drbdadm primary all

Or switch the local device to be the secondary using:

     root-shell> drbdadm secondary all

To change only a single DRBD resource, specify the resource name
instead of `all'.

You can temporarily disconnect the DRBD nodes:

     root-shell> drbdadm disconnect all

Reconnect them using `connect':

     root-shell> drbdadm connect all

For other commands and help with `drbdadm' see the DRBD documentation.


File: manual.info,  Node: ha-drbd-install-drbd-othercfg,  Prev: ha-drbd-install-drbd-using,  Up: ha-drbd-install

14.1.1.6 Additional DRBD Configuration Options
..............................................

Additional options you may want to configure:

   * `protocol' -- specifies the level of consistency to be used when
     information is written to the block device. The option is similar
     in principle to the `innodb_flush_log_at_trx_commit' option within
     MySQL. Three levels are supported:

        * `A' -- data is considered written when the information
          reaches the TCP send buffer and the local physical disk.
          There is no guarantee that the data has been written to the
          remote server or the remote physical disk.

        * `B' -- data is considered written when the data has reached
          the local disk and the remote node's network buffer. The data
          has reached the remote server, but there is no guarantee it
          has reached the remote server's physical disk.

        * `C' -- data is considered written when the data has reached
          the local disk and the remote node's physical disk.

     The preferred and recommended protocol is C, as it is the only
     protocol which ensures the consistency of the local and remote
     physical storage.

   * `size' -- if you do not want to use the entire partition space
     with your DRBD block device then you can specify the size of the
     DRBD device to be created.  The size specification can include a
     quantifier. For example, to set the maximum size of the DRBD
     partition to 1GB you would use:

          size 1G;

With the configuration file suitably configured and ready to use, you
now need to populate the lower-level device with the metadata
information, and then start the DRBD service.


File: manual.info,  Node: ha-drbd-install-mysql,  Next: ha-drbd-performance,  Prev: ha-drbd-install,  Up: ha-drbd

14.1.2 Configuring MySQL for DRBD
---------------------------------

Once you have configured DRBD and have an active DRBD device and
filesystem, you can configure MySQL to use the chosen device to store
the MySQL data.

When performing a new installation of MySQL, you can either select to
install MySQL entirely onto the DRBD device, or just configure the data
directory to be located on the new filesystem.

In either case, the files and installation must take place on the
primary node, because that is the only DRBD node on which you can mount
the DRBD device filesystem as read/write.

You should store the following files and information on your DRBD
device:

   * MySQL data files, including the binary log, and InnoDB data files.

   * MySQL configuration file (`my.cnf').

To set up MySQL to use your new DRBD device and filesystem:

  1. If you are migrating an existing MySQL installation, stop MySQL:

          $ mysqladmin shutdown

  2. Copy the `my.cnf' onto the DRBD device. If you are not already
     using a configuration file, copy one of the sample configuration
     files from the MySQL distribution.

          root-shell> mkdir /mnt/drbd/mysql
          root-shell> cp /etc/my.cnf /mnt/drbd/mysql

  3. Copy your MySQL data directory to the DRBD device and mounted
     filesystem.

          root-shell> cp -R /var/lib/mysql /drbd/mysql/data

  4. Edit the configuration file to reflect the change of directory by
     setting the value of the `datadir' option.  If you have not
     already enabled the binary log, also set the value of the
     `log-bin' option.

          datadir = /drbd/mysql/data
            log-bin = mysql-bin

  5. Create a symbolic link from `/etc/my.cnf' to the new configuration
     file on the DRBD device filesystem.

          root-shell> ln -s /drbd/mysql/my.cnf /etc/my.cnf

  6. Now start MySQL and check that the data that you copied to the
     DRBD device filesystem is present.

          root-shell> /etc/init.d/mysql start

Your MySQL data should now be located on the filesystem running on your
DRBD device. The data will be physically stored on the underlying
device that you configured for the DRBD device.  Meanwhile, the content
of your MySQL databases will be copied to the secondary DRBD node.

Note that you cannot access the information on your secondary node, as
a DRBD device working in secondary mode is not available for use.


File: manual.info,  Node: ha-drbd-performance,  Prev: ha-drbd-install-mysql,  Up: ha-drbd

14.1.3 Optimizing Performance and Reliability
---------------------------------------------

* Menu:

* ha-drbd-performance-bonded::   Using Bonded Ethernet Network Interfaces
* ha-drbd-performance-syncrate::  Optimizing the Synchronization Rate

Because of the nature of the DRBD system, the critical requirements are
for a very fast exchange of the information between the two hosts. To
ensure that your DRBD setup is available to switch over in the event of
a failure as quickly as possible, you must transfer the information
between the two hosts using the fastest method available.

Typically, a dedicated network circuit should be used for exchanging
DRBD data between the two hosts. You should then use a separate,
additional, network interface for your standard network connection. For
an example of this layout, see *Note ha-drbd-performance-sepinterface::.

FIGURE GOES HERE: DRBD Architecture

The dedicated DRBD network interfaces should be configured to use a
non-routed TCP/IP network configuration. For example, you might want to
set the primary to use 192.168.0.1 and the secondary 192.168.0.2. These
networks and IP addresses should not be part of normal network subnet.

*Note*:

The preferred setup, whenever possible, is to use a direct cable
connection (using a crossover cable with Ethernet, for example) between
the two machines. This eliminates the risk of loss of connectivity due
to switch failures.


File: manual.info,  Node: ha-drbd-performance-bonded,  Next: ha-drbd-performance-syncrate,  Prev: ha-drbd-performance,  Up: ha-drbd-performance

14.1.3.1 Using Bonded Ethernet Network Interfaces
.................................................

For a set-up where there is a high-throughput of information being
written, you may want to use bonded network interfaces.  This is where
you combine the connectivity of more than one network port, increasing
the throughput linearly according to the number of bonded connections.

Bonding also provides an additional benefit in that with multiple
network interfaces effectively supporting the same communications
channel, a fault within a single network interface in a bonded group
does not stop communication. For example, imagine you have a bonded
setup with four network interfaces providing a single interface channel
between two DRBD servers. If one network interface fails, communication
can continue on the other three without interruption, although it will
be at a lower speed

To enable bonded connections you must enable bonding within the kernel.
You then need to configure the module to specify the bonded devices and
then configure each new bonded device just as you would a standard
network device:

   * To configure the bonded devices, you need to edit the
     `/etc/modprobe.conf' file (RedHat) or add a file to the
     `/etc/modprobe.d' directory.. In each case you will define the
     parameters for the kernel module. First, you need to specify each
     bonding device:

          alias bond0 bonding

     You can then configure additional parameters for the kernel
     module. Typical parameters are the `mode' option and the `miimon'
     option.

     The `mode' option specifies how the network interfaces are used.
     The default setting is 0, which means that each network interface
     is used in a round-robin fashion (this supports aggregation and
     fault tolerance). Using setting 1 sets the bonding mode to
     active-backup. This means that only one network interface is used
     as a time, but that the link will automatically failover to a new
     interface if the primary interface fails. This settings only
     supports fault-tolerance.

     The `miimon' option enables the MII link monitoring. A positive
     value greater than zero indicates the monitoring frequency in
     milliseconds for checking each slave network interface that is
     configured as part of the bonded interface. A typical value is 100.

     You set th options within the module parameter file, and you must
     set the options for each bonded device individually:

          options bond0 miimon=100 mode=1

   * Reboot your server to enable the bonded devices.

   * Configure the network device parameters. There are two parts to
     this, you need to setup the bonded device configuration, and then
     configure the original network interfaces as 'slaves' of the new
     bonded interface.

        * For RedHat Linux:

          Edit the configuration file for the bonded device. For device
          `bond0' this would be
          `/etc/sysconfig/network-scripts/ifcfg-bond0':


               DEVICE=bond0
               BOOTPROTO=none
               ONBOOT=yes
               GATEWAY=192.168.0.254
               NETWORK=192.168.0.0
               NETMASK=255.255.255.0
               IPADDR=192.168.0.1
               USERCTL=no

          Then for each network interface that you want to be part of
          the bonded device, configure the interface as a slave to the
          'master' bond. For example, the configuration of `eth0' in
          `/etc/sysconfig/network-scripts/ifcfg-eth0' might look like
          this::

               DEVICE=eth0
               BOOTPROTO=none
               HWADDR=00:11:22:33:44:55
               ONBOOT=yes
               TYPE=Ethernet
               MASTER=bond0
               SLAVE=yes

        * For Debian Linux:

          Edit the `/etc/iftab' file and configure the logical name and
          MAC address for each devices. For example:

               eth0 mac 00:11:22:33:44:55

          Now you need to set the configuration of the devices in
          `/etc/network/interfaces':

               auto bond0
                   iface bond0 inet static
                   address 192.168.0.1
                   netmask 255.255.255.0
                   network 192.168.0.0
                   gateway 192.168.0.254
                   up /sbin/ifenslave bond0 eth0
                   up /sbin/ifenslave bond0 eth1

        * For Gentoo:

          Use `emerge' to add the `net-misc/ifenslave' package to your
          system.

          Edit the `/etc/conf.d/net' file and specify the network
          interface slaves in a bond, the dependencies and then the
          configuration for the bond itself. A sample configuration
          might look like this:

               slaves_bond0="eth0 eth1 eth2"

               config_bond0=( "192.168.0.1 netmask 255.255.255.0"  )

               depend_bond0() {
               need net.eth0 net.eth1 net.eth2
               }

          Then make sure that you add the new network interface to list
          of interfaces configured during boot:

               root-shell> rc-update add default net.bond0

Once the bonded devices are configured you should reboot your systems.

You can monitor the status of a bonded connection using the `/proc'
filesystem:

     root-shell> cat /proc/net/bonding/bond0
     Bonding Mode: fault-tolerance (active-backup)
     Primary Slave: None
     Currently Active Slave: eth1
     MII Status: up
     MII Polling Interval (ms): 100
     Up Delay (ms): 200
     Down Delay (ms): 200
     Slave Interface: eth1
     MII Status: up
     Link Failure Count: 0
     Permanent HW addr: 00:11:22:33:44:55
     Slave Interface: eth2
     MII Status: up
     Link Failure Count: 0
     Permanent HW addr: 00:11:22:33:44:56


File: manual.info,  Node: ha-drbd-performance-syncrate,  Prev: ha-drbd-performance-bonded,  Up: ha-drbd-performance

14.1.3.2 Optimizing the Synchronization Rate
............................................

The `syncer rate' configuration parameter should be configured with
care as the synchronization rate can have a significant effect on the
performance of the DRBD setup in the event of a node or disk failure
where the information is being synchronized from the Primary to the
Secondary node.

In DRBD, there are two distinct ways of data being transferred between
peer nodes:

   * _Replication_ refers to the transfer of modified blocks being
     transferred from the primary to the secondary node. This happens
     automatically when the block is modified on the primary node, and
     the replication process uses whatever bandwidth is available over
     the replication link. The replication process cannot be throttled,
     because you want to transfer of the block information to happen as
     quickly as possible during normal operation.

   * _Synchronization_ refers to the process of bringing peers back in
     sync after some sort of outage, due to manual intervention, node
     failure, disk swap, or the initial setup. Synchronization is
     limited to the `syncer rate' configured for the DRBD device.

Both replication and synchronization can take place at the same time.
For example, the block devices can be being synchronized while they are
actively being used by the primary node. Any I/O that updates on the
primary node will automatically trigger replication of the modified
block. In the event of a failure within an HA environment, it is highly
likely that synchronization and replication will take place at the same
time.

Unfortunately, if the synchronization rate is set too high, then the
synchronization process will use up all the available network bandwidth
between the primary and secondary nodes. In turn, the bandwidth
available for replication of changed blocks is zero, which means
replication will stall and I/O will block, and ultimately the
application will fail or degrade.

To avoid enabling the `syncer rate' to consume the available network
bandwidth and prevent the replication of changed blocks you should set
the `syncer rate' to less than the maximum network bandwidth.

Depending on the application, you may wish to limit the synchronization
rate. For example, on a busy server you may wish to configure a
significantly slower synchronization rate to ensure the replication
rate is not affected.


File: manual.info,  Node: ha-heartbeat,  Prev: ha-drbd,  Up: ha-overview

14.2 Using Linux HA Heartbeat
=============================

* Menu:

* ha-heartbeat-config::          Heartbeat Configuration
* ha-heartbeat-drbd::            Using Heartbeat with MySQL and DRBD
* ha-heartbeat-drbd-dopd::       Using Heartbeat with DRBD and `dopd'
* ha-heartbeat-errors::          Dealing with System Level Errors

The Heartbeat program provides a basis for verifying the availability
of resources on one or more systems within a cluster.  In this context
a resource includes MySQL, the filesystems on which the MySQL data is
being stored and, if you are using DRBD, the DRBD device being used for
the filesystem. Heartbeat also manages a virtual IP address, and the
virtual IP address should be used for all communication to the MySQL
instance.

A cluster within the context of Heartbeat is defined as two computers
notionally providing the same service. By definition, each computer in
the cluster is physically capable of providing the same services as all
the others in the cluster. However, because the cluster is designed for
high-availability, only one of the servers is actively providing the
service at any one time. Each additional server within the cluster is a
'hot-spare' that can be brought into service in the event of a failure
of the master, it's next connectivity or the connectivity of the
network in general.

The basics of Heartbeat are very simple. Within the Heartbeat cluster
(see *Note ha-heartbeat-overview::, each machine sends a 'heartbeat'
signal to the other hosts in the cluster. The other cluster nodes
monitor this heartbeat. The heartbeat can be transmitted over many
different systems, including shared network devices, dedicated network
interfaces and serial connections.  Failure to get a heartbeat from a
node is treated as failure of the node. Although we don't know the
reason for the failure (it could be an OS failure, a hardware failure
in the server, or a failure in the network switch), it is safe to
assume that if no heartbeat is produced there is a fault.

FIGURE GOES HERE: DRBD Architecture

In addition to checking the heartbeat from the server, the system can
also check the connectivity (using `ping') to another host on the
network, such as the network router. This allows Heartbeat to detect a
failure of communication between a server and the router (and therefore
failure of the server, since it is no longer capable of providing the
necessary service), even if the heartbeat between the servers in the
clusters is working fine.

In the event of a failure, the resources on the failed host are
disabled, and the resources on one of the replacement hosts is enabled
instead. In addition, the Virtual IP address for the cluster is
redirected to the new host in place of the failed device.

When used with MySQL and DRBD, the MySQL data is replicated from the
master to the slave using the DRBD device, but MySQL is only running on
the master. When the master fails, the slave switches the DRBD devices
to be primary, the filesystems on those devices are mounted, and MySQL
is started. The original master (if still available) has it's resources
disabled, which means shutting down MySQL and unmounting the
filesystems and switching the DRBD device to secondary.


File: manual.info,  Node: ha-heartbeat-config,  Next: ha-heartbeat-drbd,  Prev: ha-heartbeat,  Up: ha-heartbeat

14.2.1 Heartbeat Configuration
------------------------------

Heartbeat configuration requires three files located in `/etc/ha.d'.
The `ha.cf' contains the main heartbeat configuration, including the
list of the nodes and times for identifying failures.  `haresources'
contains the list of resources to be managed within the cluster. The
`authkeys' file contains the security information for the cluster.

The contents of these files should be identical on each host within the
Heartbeat cluster. It's important that you keep these files in sync
across all the hosts. Any changes in the information on one host should
be copied to the all the others.

For these examples n example of the `ha.cf' file is shown below:

     logfacility local0
     keepalive 500ms
     deadtime 10
     warntime 5
     initdead 30
     mcast bond0 225.0.0.1 694 2 0
     mcast bond1 225.0.0.2 694 1 0
     auto_failback off
     node drbd1
     node drbd2

The individual lines in the file can be identified as follows:

   * `logfacility' -- sets the logging, in this case setting the
     logging to use `syslog'.

   * `keepalive' -- defines how frequently the heartbeat signal is sent
     to the other hosts.

   * `deadtime'-- the delay in seconds before other hosts in the
     cluster are considered 'dead' (failed).

   * `warntime' -- the delay in seconds before a warning is written to
     the log that a node cannot be contacted.

   * `initdead' -- the period in seconds to wait during system startup
     before the other host is considered to be down.

   * `mcast' -- defines a method for sending a heartbeat signal. In the
     above example, a multicast network address is being used over a
     bonded network device. If you have multiple clusters then the
     multicast address for each cluster should be unique on your
     network. Other choices for the heartbeat exchange exist, including
     a serial connection.

     If you are using multiple network interfaces (for example, one
     interface for your server connectivity and a secondary and/or
     bonded interface for your DRBD data exchange) then you should use
     both interfaces for your heartbeat connection. This decreases the
     chance of a transient failure causing a invalid failure event.

   * `auto_failback' -- sets whether the original (preferred) server
     should be enabled again if it becomes available. Switching this to
     `on' may cause problems if the preferred went offline and then
     comes back on line again. If the DRBD device has not been synced
     properly, or if the problem with the original server happens again
     you may end up with two different datasets on the two servers, or
     with a continually changing environment where the two servers
     flip-flop as the preferred server reboots and then starts again.

   * `node' -- sets the nodes within the Heartbeat cluster group. There
     should be one `node' for each server.

An optional additional set of information provides the configuration
for a ping test that will check the connectivity to another host. You
should use this to ensure that you have connectivity on the public
interface for your servers, so the ping test should be to a reliable
host such as a router or switch. The additional lines specify the
destination machine for the `ping', which should be specified as an IP
address, rather than a hostname; the command to run when a failure
occurs, the authority for the failure and the timeout before an
non-response triggers a failure. A sample configure is shown below:

     ping 10.0.0.1
     respawn hacluster /usr/lib64/heartbeat/ipfail
     apiauth ipfail gid=haclient uid=hacluster
     deadping 5

In the above example, the `ipfail' command, which is part of the
Heartbeat solution, is called on a failure and 'fakes' a fault on the
currently active server. You need to configure the user and group ID
under which the command should be executed (using the `apiauth'). The
failure will be triggered after 5 seconds.

*Note*:

The `deadping' value must be less than the `deadtime' value.

The `auth_keys' file holds the authorization information for the
Heartbeat cluster. The authorization relies on a single unique 'key'
that is used to verify the two machines in the Heartbeat cluster. It is
used only to confirm that the two machines are in the same cluster and
is used to ensure that the


File: manual.info,  Node: ha-heartbeat-drbd,  Next: ha-heartbeat-drbd-dopd,  Prev: ha-heartbeat-config,  Up: ha-heartbeat

14.2.2 Using Heartbeat with MySQL and DRBD
------------------------------------------

To use Heartbeat in combination with MySQL you should be using DRBD
(see *Note ha-drbd::) or another solution that allows for sharing of
the MySQL database files in event of a system failure. In these
examples, DRBD is used as the data sharing solution.

Heartbeat manages the configuration of different resources to manage
the switching between two servers in the event of a failure. The
resource configuration defines the individual services that should be
brought up (or taken down) in the event of a failure.

The `haresources' file within `/etc/ha.d' defines the resources that
should be managed, and the individual resource mentioned in this file in
turn relates to scripts located within `/etc/ha.d/resource.d'. The
resource definition is defined all on one line:

     drbd1 drbddisk Filesystem::/dev/drbd0::/drbd::ext3 mysql 10.0.0.100

The line is notionally split by whitespace. The first entry (`drbd1')
is the name of the preferred host, i.e.  the server that is normally
responsible for handling the service.  The last field is virtual IP
address or name that should be used to share the service. This is the
IP address that should be used to connect to the MySQL server. It will
automatically be allocated to the server that is active when Heartbeat
starts.

The remaining fields between these two fields define the resources that
should be managed. Each Field should contain the name of the resource
(and each name should refer to a script within `/etc/ha.d/resource.d').
In the event of a failure, these resources are started on the backup
server by calling the corresponding script (with a single argument,
`start'), in order from left to right. If there are additional
arguments to the script, you can use a double colon to separate each
additional argument.

In the above example, we manage the following resources:

   * `drbddisk' -- the DRBD resource script, this will switch the DRBD
     disk on the secondary host into primary mode, making the device
     read/write.

   * `Filesystem' -- manages the Filesystem resource. In this case we
     have supplied additional arguments to specify the DRBD device,
     mount point and filesystem type.  When executed this should mount
     the specified filesystem.

   * `mysql' -- manages the MySQL instances and starts the MySQL
     server. You should copy the `mysql.resource' file from the
     `support-files' directory from any MySQL release into the
     `/etc/ha.d/resources.d' directory.

     If this file is not available in your distribution, you can use
     the following as the contents of the
     `/etc/ha.d/resource.d/mysql.resource' file:

          #!/bin/bash
          #
          # This script is inteded to be used as resource script by heartbeat
          #
          # Mar 2006 by Monty Taylor
          #
          ###

          . /etc/ha.d/shellfuncs

          case "$1" in
              start)
                  res=`/etc/init.d/mysql start`
                  ret=$?
                  ha_log $res
                  exit $ret
                  ;;
              stop)
                  res=`/etc/init.d/mysql stop`
                  ret=$?
                  ha_log $res
                  exit $ret
                  ;;
              status)
                  if [ `ps -ef | grep '[m]ysqld'` ] ; then
                     echo "running"
                  else
                     echo "stopped"
                  fi
                  ;;
              *)
                  echo "Usage: mysql {start|stop|status}"
                  exit 1
                  ;;
          esac

          exit 0

If you want to be notified of the failure by email, you can add another
line to the `haresources' file with the address for warnings and the
warning text:

     MailTo::youremail@address.com::DRBDFailure

With the Heartbeat configuration in place, copy the `haresources',
`authkeys' and `ha.cf' files from your primary and secondary servers to
make sure that the configuration is identical. Then start the Heartbeat
service, either by calling `/etc/init.d/heartbeat start' or by rebooting
both primary and secondary servers.

You can test the configuration by running a manual failover, connect to
the primary node and run:

     root-shell> /usr/lib64/heartbeat/hb_standby

This will cause the current node to relinquish its resources cleanly to
the other node.


File: manual.info,  Node: ha-heartbeat-drbd-dopd,  Next: ha-heartbeat-errors,  Prev: ha-heartbeat-drbd,  Up: ha-heartbeat

14.2.3 Using Heartbeat with DRBD and `dopd'
-------------------------------------------

As a further extension to using DRBD and Heartbeat together, you can
enable `dopd'. The `dopd' daemon handles the situation where a DRBD
node is out of date compared to the master and prevents the slave from
being promoted to master in the event of a failure. This stops a
situation where you have two machines that have been masters ending up
different data on the underlying device.

For example, imagine that you have a two server DRBD setup, master and
slave. If the DRBD connectivity between master and slave fails then the
slave would be out of the sync with the master. If Heartbeat identifies
a connectivity issue for master and then switches over to the slave,
the slave DRBD device will be promoted to the primary device, even
though the data on the slave and the master is not in synchronization.

In this situation, with `dopd' enabled, the connectivity failure
between the master and slave would be identified and the metadata on
the slave wold be set to `Outdated'. Heartbeat will then refuse to
switch over to the slave even if the master failed. In a dual-host
solution this would effectively render the cluster out of action, as
there is no additional fail over server. In an HA cluster with three or
more servers, control would be passed to the slave that has an up to
date version of the DRBD device data.

To enable `dopd', you need to modify the Heartbeat configuration and
specify `dopd' as part of the commands executed during the monitoring
process. Add the following lines to your `ha.cf' file:

     respawn hacluster /usr/lib/heartbeat/dopd
     apiauth dopd gid=haclient uid=hacluster

Make sure you make the same modification on both your primary and
secondary nodes.

You will need to reload the Heartbeat configuration:

     root-shell> /etc/init.d/heartbeat reload

You will also need to modify your DRBD configuration by configuration
the `outdate-peer' option. You will need to add the configuration line
into the `common' section of `/etc/drbd.conf' on both hosts. An example
of the full block is shown below:

     common {
       handlers {
         outdate-peer "/usr/lib/heartbeat/drbd-peer-outdater";
       }
     }

Finally, set the `fencing' option on your DRBD configured resources:

     resource my-resource {
       disk {
         fencing    resource-only;
       }
     }

Now reload your DRBD configuration:

     root-shell> drbdadmin adjust all

You can test the system by unplugging your DRBD link and monitoring the
output from `/proc/drbd'.


File: manual.info,  Node: ha-heartbeat-errors,  Prev: ha-heartbeat-drbd-dopd,  Up: ha-heartbeat

14.2.4 Dealing with System Level Errors
---------------------------------------

Because a kernel panic or oops may indicate potential problem with your
server, you should configure your server to remove itself from the
cluster in the event of a problem. Typically on a kernel panic your
system will automatically trigger a hard reboot. For a kernel oops a
reboot may not happen automatically, but the issue that caused that
oops may still lead to potential problems.

You can force a reboot by setting the `kernel.panic' and
`kernel.panic_on_oops' parameters of the kernel control file
`/etc/sysctl.conf'. For example:

      kernel.panic_on_oops = 1
      kernel.panic = 1

You can also set these parameters during runtime by using the `sysctl'
command. You can either specify the parameters on the command line:

     $ sysctl -w kernel.panic=1

Or you can edit your `sysctl.conf' file and then reload the
configuration information:

     $ sysctl -p

By setting both these parameters to a positive value (actually the
number of seconds to wait before triggering the reboot), the system
will reboot. Your second heartbeat node should then detect that the
server is down and then switch over to the failover host.


File: manual.info,  Node: ha-vm,  Next: ha-memcached,  Prev: ha-overview,  Up: Top

15 MySQL and Virtualization
***************************

* Menu:

* ha-vm-commonissues::           Common Issues with Virtualization
* ha-vm-aws::                    Using MySQL within an Amazon EC2 Instance
* ha-vm-resources::              Virtualization Resources

Using virtualization can be an effective way of better utilizing the
hardware of your machine when using MySQL, or to provide improved
security or isolation of different instances of MySQL on the same
machine. In some circumstances, virtualization may be a suitable
solution for scaling out your database environment by enabling you to
easily deploy additional instances of a pre-configured MySQL server and
application environment to new virtualization hosts.

With any virtualization solution there is often a tradeoff between the
flexibility and ease of deployment and performance, or between the
potential performance advantage and complexities of effectively
configuring multiple instances of MySQL to reside within a single
physical host.

Different issues are experienced according to the virtualization
environment you are using. Virtualization generally falls into one of
the following categories:

   * *Native virtualization*, including products like VMware
     Workstation, Parallels Desktop/Parallels Workstation, Microsoft
     Virtual PC and VirtualBox, all work by acting as an application
     that runs within an existing operating system environment. Recent
     versions can take advantage of the virtualization extensions in
     the Intel and AMD CPUs to help improve performance.

     The application-based solutions have a number of advantages,
     including the ability to prioritize CPU usage (including multiple
     CPUs) and easily run multiple virtualized environments
     simultaneously.

     With these solutions, you also have the ability to easily create a
     virtualized environment that can be packaged and shared among
     different virtualization hosts. For example, you can create a
     MySQL environment and configuration that can be deployed multiple
     times to help extend an existing scalability or HA environment.

     The major disadvantage of this type of virtualization environment
     is the effect of the host on the performance of the virtualization
     instances. Disk storage is typically provided by using one or more
     files on the host OS which are then emulated to provide physical
     disks within the virtual instance. Other resources on the host are
     similarly shared, including CPU, network interfaces and additional
     devices (USB). It is also difficult to directly share lower-level
     components, such as PCI devices and that the ability to take
     advantage of RAID storage solutions.

   * *Paravirtualization (Hypervisor)*, including Xen, Solaris xVM
     (based on Xen), VMware ESX Server, Windows Server 2008 Hyper-V, and
     Solaris Logical Domains (LDOM), work by running a specialized
     version of the host operating system. The host OS then allows
     slightly modified versions of different operating systems to run
     within the virtualized environment.

     With paravirtualization, the level of performance and the control
     over the underlying hardware used to support the virtualized
     environments is higher than native virtualization solutions. For
     example, using paravirtualization you can dedicate individual CPU
     cores, RAM, disk drives and even PCI devices to be accessible to
     individual and specific virtual instances.

     For example, within a paravirtualized environment you could
     dedicate a physical disk drive or subsystem to a particular
     virtual environment and gain a performance benefit over a typical
     file-based solution virtual disk.

   * *Operating system-level virtualization*, including BSD jails, and
     Solaris Containers/Zones, offer methods for isolating different
     instances of an operating system environment while sharing the
     same hardware environment. Unlike the other virtualization
     solutions, operating system level virtualization is not normally
     used to run other operating systems, but instead to provide a
     level of security isolation and resource control within the core
     operating environment.

     The isolation of these different instances is the key advantage of
     this type of virtualization. Each virtualized instance sees its
     environment as if it were completely different system. The
     solution can be an effective method to provide isolated computing
     resources for different departments or users, or to provide unique
     instances for testing and development.

The main reasons for using virtualization, particularly with a database
or an application stack that includes a database component, include:

   * *Security* -- separate instances of different operating systems
     running within a single host but with effective isolation from
     each other. When used with MySQL, you can provide an increased
     level of security between different instances of each server.

   * *Consolidation* -- merging a number of individual systems with a
     relatively small load onto a single, larger, server. This can help
     reduce footprint and energy costs, or make more efficient use of a
     larger machine.  Performance is the main issue with this solution
     as the load of many MySQL databases running in individual virtual
     instances on a single machine can be considerable.

   * *Development/QA/Testing* -- by creating different instances of
     different environments and operating systems you can test your
     MySQL-based application in different environments.

   * *Scalability* -- although using virtualization imposes a
     performance hit, many virtualization solutions allow you to create
     a packaged version of an environment, including MySQL and the
     other application components. By distributing the virtualization
     environment package to new hosts you can often very quickly scale
     out by adding new hosts and deploying the virtualized environment.

The remainder of this chapter looks at common issues with using MySQL
in a virtualized environment and tips for using MySQL within different
virtualization tools.

For advice on common issues and problems, including performance and
configuration issues, when using virtualized instances, see *Note
ha-vm-commonissues::.


File: manual.info,  Node: ha-vm-commonissues,  Next: ha-vm-aws,  Prev: ha-vm,  Up: ha-vm

15.1 Common Issues with Virtualization
======================================

* Menu:

* ha-vm-commonissues-performance::  Virtualization Performance Issues
* ha-vm-commonissues-storage::   Virtualization Storage Issues
* ha-vm-commonissues-networking::  Virtualization Networking Issues

There are many issues related to using MySQL within a virtualized
environment that are common across the different virtualization types.
Most are directly related to the performance or security of the
environment in which you are deploying the MySQL server compared to the
host on which you are running the virtualization solution.

Before deciding to use virtualization as a solution for your database,
you should ensure that the expected load for the server and the
expected performance when run in a virtualized environment meet your
needs and requirements.

To help you determine the issues and some of the potential solutions,
use the following sections:

   * For general performance issues and the problems and probably
     causes of performance issues, see *Note
     ha-vm-commonissues-performance::.

   * Disk and storage concerns directly affect database storage because
     most database access is limited by the I/O bandwidth.  For some
     examples and issues, see *Note ha-vm-commonissues-storage::.

   * Issues related to network configuration and performance may need
     more careful planning, especially if you are using
     network-specific technologies such as MySQL replication. For
     further examples and details, see *Note
     ha-vm-commonissues-networking::.


File: manual.info,  Node: ha-vm-commonissues-performance,  Next: ha-vm-commonissues-storage,  Prev: ha-vm-commonissues,  Up: ha-vm-commonissues

15.1.1 Virtualization Performance Issues
----------------------------------------

Often the biggest consideration is the performance of a virtualized
environment once hosted. In most cases, the virtualized environment
involves some level of emulation of one or more of the hardware
interfaces (CPU, network or disk) of the host environment. The effect
is to reduce the effective performance of the virtualized environment
compared to running an application natively on the host.

Some core resourcing issues to be aware of include:

   * Using virtualization does not reduce the amount of CPU required to
     support a particular application or environment.  If your
     application stack requires 2GB of RAM on an individual machine,
     the same RAM requirement will apply within your virtualized
     environment. The additional overhead of the virtualization layer
     and host operating system or environment often mean that you will
     need 2.5GB or 3GB of RAM to run the same application within the
     virtualized environment.

     You should configure your virtualization environment with the
     correct RAM allocation according to your applications needs, and
     not to maximize the number of virtualized environments that you
     can execute within the virtualization host.

   * Virtualization of the CPU resources is more complex. If your MySQL
     database and application stack do not have a high CPU load, then
     consolidating multiple environments onto a single host is often
     more efficient. You should keep in mind that at peak times your
     application and database CPU requirement may need to grow beyond
     your default allocation.

     With some virtualization environments (Xen, Solaris Containers,
     Solaris LDOMs) you can dedicate CPU or core to a virtual instance.
     You should use this functionality to improve performance for
     database or application loads that have a high constant CPU
     requirement as the performance benefit will outweigh the
     flexibility of dynamic allocation of the CPU resources.

   * Contention of resources within the host should be taken into
     account. In a system with high CPU loads, even when dedicating RAM
     and CPU resources, the I/O channels and interfaces to storage and
     networking resources may exceed the capacity of the host.
     Solutions such as Xen and Solaris LDOMs dedicate specific
     resources to individual virtual instances, but this will not
     eliminate the effects of the overall load on the host.

   * If your database application is time sensitive, including logging
     and real-time database applications, or you are using MySQL
     Cluster, then the effects of virtualization may severely reduce
     the performance of your application. Because of the way the
     virtualized instances are executed and shared between CPUs and the
     effects of load on other resources, the response times for your
     database or application may be much higher than normal. This is
     especially true if you are running a large number of virtualized
     instances on a single host.

   * Be aware of the limitation of using a single host to run multiple
     virtualized instances. In the event of a machine or component
     failure, the problem will affect more than just one database
     instance. For example, a failure in a storage device could bring
     down all your virtualized instances.  Using a RAID solution that
     supports fault tolerance (RAID levels 1,3,4,5 or 6) will help
     protect you from the effects of this.


File: manual.info,  Node: ha-vm-commonissues-storage,  Next: ha-vm-commonissues-networking,  Prev: ha-vm-commonissues-performance,  Up: ha-vm-commonissues

15.1.2 Virtualization Storage Issues
------------------------------------

Due to the random I/O nature of any database solution, running MySQL
within a virtualized environment places a heavy load on the storage
solution you are using. To help keep the performance of your
virtualized solution at the highest level, you should use the following
notes to help configure your systems.

   * Some virtualization solutions allow you to use a physical disk
     directly within your virtual host as if it were a local disk. You
     should use this whenever possible to ensure that disk contention
     issues do not affect the performance of your virtual environment.

     When running multiple virtual machines, you should use an
     individual disk for each virtual instance. Using a single disk and
     multiple partitions, with each partition dedicated to a virtual
     host, will lead to the same contention issues.

   * If you are using standard file-based storage for your virtualized
     disks:

        * File-based storage is subject to fragmentation on the host
          disk. To prevent fragmentation, create a fixed-size disk
          (that is, one where the entire space for the disk file is
          preallocated) instead of a dynamic disk that will grow with
          usage. Also be prepared to defragment the disk hosting the
          files at regular intervals to reduce the fragmentation.

        * Use separate disk files for the operating system and database
          disks, and try to avoid partitioning a disk file as this
          increases the contention within the file.

        * Use a high-performance disk solution, such as RAID or SAN, to
          store the disk files for your virtualized environments. This
          will improve the performance of what is essentially a large
          single file on a physical device.

        * When running a number of different virtualized environments
          within a single host, do not use the same physical host drive
          for multiple virtual disks. Instead, spread the virtual disks
          among multiple physical disks.  Even when using a RAID
          device, be aware that each virtual host is equivalent to
          increasing the load linearly on the host RAID device.


File: manual.info,  Node: ha-vm-commonissues-networking,  Prev: ha-vm-commonissues-storage,  Up: ha-vm-commonissues

15.1.3 Virtualization Networking Issues
---------------------------------------

When running multiple virtual machines on a host, you should be aware
of the networking implications of each virtualized instance. If your
host machine has only one network card, then you will be sharing the
networking throughput for all of your machines through only one card,
and this may severely limit the performance of your virtual
environments.

If possible, you should use multiple network cards to support your
virtualized instances. Depending on the expected load of each instance,
you should dedicate or spread the allocation of the virtual network
devices across these physical devices to ensure that you do not reach
saturation.

If you are using packaged virtual machines as the basis for deployment
of your MySQL database solution, you should make sure that the network
interfaces are correctly reconfigured. Some solutions duplicate the
hardware MAC address which will cause problems when you start up
additional instances of the same virtualized environment.


File: manual.info,  Node: ha-vm-aws,  Next: ha-vm-resources,  Prev: ha-vm-commonissues,  Up: ha-vm

15.2 Using MySQL within an Amazon EC2 Instance
==============================================

* Menu:

* ha-vm-aws-setup::              Setting Up MySQL on an EC2 AMI
* ha-vm-aws-instance::           EC2 Instance Limitations
* ha-vm-aws-deploy::             Deploying a MySQL Database Using EC2

The Amazon Elastic Compute Cloud (EC2) service provides virtual servers
that you can build and deploy to run a variety of different
applications and services, including MySQL. The EC2 service is based
around the Xen framework, supporting x86, Linux based, platforms with
individual instances of a virtual machine referred to as an Amazon
Machine Image (AMI). You have complete (root) access to the AMI
instance that you create, allowing you to configure and install your
AMI in any way you choose.

To use EC2, you create an AMI based on the configuration and
applications that you want to use and upload the AMI to the Amazon
Simple Storage Service (S3). From the S3 resource, you can deploy one
or more copies of the AMI to run as an instance within the EC2
environment. The EC2 environment provides management and control of the
instance and contextual information about the instance while it is
running.

Because you can create and control the AMI, the configuration, and the
applications, you can deploy and create any environment you choose.
This includes a basic MySQL server in addition to more extensive
replication, HA and scalability scenarios that enable you to take
advantage of the EC2 environment, and the ability to deploy additional
instances as the demand for your MySQL services and applications grow.

To aid the deployment and distribution of work, three different Amazon
EC2 instances are available, small (identified as `m1.small'), large
(`m1.large') and extra large (`m1.xlarge'). The different types provide
different levels of computing power measured in EC2 computer units
(ECU). A summary of the different instance configurations is shown here.

                   Small              Large              Extra Large
Platform           32-bit             64-bit             64-bit
CPU cores          1                  2                  4
ECUs               1                  4                  8
RAM                1.7GB              7.5GB              15GB
Storage            150GB              840GB              1680GB
I/O Performance    Medium             High               High

The typical model for deploying and using MySQL within the EC2
environment is to create a basic AMI that you can use to hold your
database data and application. Once the basic environment for your
database and application has been created you can then choose to deploy
the AMI to a suitable instance. Here the flexibility of having an AMI
that can be re-deployed from the small to the large or extra large EC2
instance makes it easy to upgrade the hardware environment without
rebuilding your application or database stack.

To get started with MySQL on EC2, including information on how to set
up and install MySQL within an EC2 installation and how to port and
migrate your data to the running instance, see *Note ha-vm-aws-setup::.

For tips and advice on how to create a scalable EC2 environment using
MySQL, including guides on setting up replication, see *Note
ha-vm-aws-deploy::.


File: manual.info,  Node: ha-vm-aws-setup,  Next: ha-vm-aws-instance,  Prev: ha-vm-aws,  Up: ha-vm-aws

15.2.1 Setting Up MySQL on an EC2 AMI
-------------------------------------

There are many different ways of setting up an EC2 AMI with MySQL,
including using any of the pre-configured AMIs supplied by Amazon.

The default _Getting Started_ AMI provided by Amazon uses Fedora Core
4, and you can install MySQL by using `yum':

     shell> yum install mysql

This will install both the MySQL server and the Perl DBD::mysql driver
for the Perl DBI API.

Alternatively, you can use one of the AMIs that include MySQL within
the standard installation.

Finally, you can also install a standard version of MySQL downloaded
from the MySQL website. The installation process and instructions are
identical to any other installation of MySQL on Linux. See *Note
installing::.

The standard configuration for MySQL places the data files in the
default location, `/var/lib/mysql'. The default data directory on an
EC2 instance is `/mnt' (although on the large and extra large instance
you can alter this configuration). You must edit `/etc/my.cnf' to set
the `datadir' option to point to the larger storage area.

*Important*:

The first time you use the main storage location within an EC2 instance
it needs to be initialized. The initialization process starts
automatically the first time you write to the device. You can start
using the device right away, but the write performance of the new
device is significantly lower on the initial writes until the
initialization process has finished.

To avoid this problem when setting up a new instance, you should start
the initialization process before populating your MySQL database. One
way to do this is to use `dd' to write to the filesystem:

     root-shell> dd if=/dev/zero of=initialize bs=1024M count=50

The preceding will create a 50GB on the filesystem and start the
initialization process. You should delete the file once the process has
finished.

The initialization process can be time-consuming. On the small
instance, initialization will take between two and three hours. For the
large and extra large drives, the initialization will be 10 or 20
hours, respectively.

In addition to configuring the correct storage location for your MySQL
data files, you should also consider setting the following other
settings in your instance before you save the instance configuration
for deployment:

   * Set the MySQL server ID so that when you use it for replication
     the ID information is set correctly.

   * Enabling binary logging so that replication can be initialized
     without starting and stopping the server.

   * Set the caching and memory parameters for your storage engines.
     There are no limitations or restrictions on what storage engines
     you use in your EC2 environment. Choose a configuration, possibly
     using one of the standard configurations provided with MySQL
     appropriate for the instance on which you expect to deploy. The
     large and extra large instances have RAM that can be dedicated to
     caching.  Be aware that if you choose to install `memcached' on
     the servers as part of your application stack you must ensure
     there is enough memory for both MySQL and `memcached'.

Once you have configured your AMI with MySQL and the rest of your
application stack, you should save the AMI so that you can deploy and
reuse the instance.

Once you have your application stack configured in an AMI, populating
your MySQL database with data should be performed by creating a dump of
your database using `mysqldump', transferring the dump to the EC2
instance, and then reloading the information into the EC2 instance
database.

Before using your instance with your application in a production
situation you should be aware of the limitations of the EC2 instance
environment. See *Note ha-vm-aws-instance::.  To begin using your MySQL
AMI, you should consult the notes on deployment. See *Note
ha-vm-aws-deploy::.


File: manual.info,  Node: ha-vm-aws-instance,  Next: ha-vm-aws-deploy,  Prev: ha-vm-aws-setup,  Up: ha-vm-aws

15.2.2 EC2 Instance Limitations
-------------------------------

There are some limitations of the EC2 instances that you should be
aware of before deploying your applications. Although these shouldn't
affect your ability to deploy within the Amazon EC2 environment, they
may alter the way you setup and configure your environment to support
your application.

   * Data stored within instances is not persistent. If you create an
     instance and populate the instance with data, then the data will
     only remain in place while the machine is running. The data will
     survive a reboot. If you shut down the instance, any data it
     contained will be lost.

     To ensure that you do not lose information, take regular backups
     using `mysqldump'. If the data being stored is critical, consider
     using replication to keep a `live' backup of your data in the
     event of a failure. When creating a backup, write the data to the
     Amazon S3 service to avoid the transfer charges applied when
     copying data offsite.

   * EC2 instances are not persistent. If the hardware on which an
     instance is running fails, then the instance will be shut down.
     This can lead to loss of data or service.

   * If you want to use replication with your EC2 instances to a
     non-EC2 environment, be aware of the transfer costs to and from
     the EC2 service. Data transfer between different EC2 instances is
     free, so using replication within the EC2 environment does not
     incur additional charges.

   * Certain HA features are either not directly supported, or have
     limiting factors or problems that may reduce their utility. For
     example, using DRBD or MySQL Cluster may not work. The default
     storage configuration is also not redundant. You can use
     software-based RAID to improve redundancy, but this implies a
     further performance hit.


File: manual.info,  Node: ha-vm-aws-deploy,  Prev: ha-vm-aws-instance,  Up: ha-vm-aws

15.2.3 Deploying a MySQL Database Using EC2
-------------------------------------------

Because you cannot guarantee the uptime and availability of your EC2
instances, when deploying MySQL within the EC2 environment you should
use an approach that enables you to easily distribute work among your
EC2 instances. There are a number of ways of doing this. Using sharding
techniques, where you split the application across multiple servers
dedicating specific blocks of your dataset and users to different
servers is an effective way of doing this. As a general rule, it is
easier to create more EC2 instances to support more users than to
upgrade the instance to a larger machine.

The EC2 architecture means that you should treat the EC2 instances as
temporary, cache-based solutions, rather than as a long-term, high
availability solution. In addition to using multiple machines, you
should also take advantage of other services, such as `memcached' to
provide additional caching for your application to help reduce the load
on the MySQL server so that it can concentrate on writes. On the large
and extra large instances within EC2, the RAM available can be used to
provide a large memory cache for data.

Most types of scale out topology that you would use with your own
hardware can be used and applied within the EC2 environment.  However,
you should be use the limitations and advice already given to ensure
that any potential failures do not lose you any data. Also, because the
relative power of each EC2 instance is so low, you should be prepared
to alter your application to use sharding and add further EC2 instances
to improve the performance of your application.

For example, take the typical scale-out environment shown following,
where a single master replicates to one or more slaves (three in this
example), with a web server running on each replication slave.

Typical standard scale out structure

You can reproduce this structure completely within the EC2 environment,
using an EC2 instance for the master, and one instance for each of the
web and MySQL slave servers.

*Note*:

Within the EC2 environment, internal (private) IP addresses used by the
EC2 instances are constant. You should always use these internal
addresses and names when communicating between instances. Only use
public IP addresses when communicating with the outside world - for
example, when publicizing your application.

To ensure reliability of your database, you should add at least one
replication slave dedicated to providing an active backup and storage
to the Amazon S3 facility. You can see an example of this in the
following topology.

Typical standard scale out structure with backup using EC2

*Using `memcached'* within your EC2 instances should provide better
performance. The large and extra large instances have a significant
amount of RAM. To use `memcached' in your application, when loading
information from the database, first check whether the item exists in
the cache. If the data you are looking for exists in the cache, use it.
If not, reload the data from the database and populate the cache.

*Sharding* divides up data in your entire database by allocating
individual machines or machine groups to provide a unique set of data
according to an appropriate group. For example, you might put all users
with a surname ending in the letters A-D onto a single server. When a
user connects to the application and their surname is known, queries
can be redirected to the appropriate MySQL server.

When using sharding with EC2 you should separate the web server and
MySQL server into separate EC2 instances, and then apply the sharding
decision logic into your application. Once you know which MySQL server
you should be using for accessing the data you then distribute queries
to the appropriate server. You can see a sample of this in the
following illustration.

Using sharding in EC2 to spread the load

*Warning*:

With sharding and EC2 you should be careful that the potential for
failure of an instance does not affect your application.  If the EC2
instance that provides the MySQL server for a particular shard fails,
then all of the data on that shard will be unavailable.


File: manual.info,  Node: ha-vm-resources,  Prev: ha-vm-aws,  Up: ha-vm

15.3 Virtualization Resources
=============================

For more information on virtualization, see the following links:

   * MySQL Virtualization Forum (http://forums.mysql.com/list.php?149)

   * Amazon Elastic Compute Cloud (Amazon EC2)
     (http://aws.amazon.com/ec2)

   * MySQL and Cloud Computing
     (http://www.mysql.com/products/enterprise/cloud.html)

   * MySQL Enterprise for Amazon EC2
     (http://www.mysql.com/products/enterprise/ec2.html)


File: manual.info,  Node: ha-memcached,  Next: mysql-proxy,  Prev: ha-vm,  Up: Top

16 Using MySQL with `memcached'
*******************************

* Menu:

* ha-memcached-install::         Installing `memcached'
* ha-memcached-using::           Using `memcached'
* ha-memcached-interfaces::      `memcached' Interfaces
* ha-memcached-stats::           Getting `memcached' Statistics
* ha-memcached-faq::             `memcached' FAQ

The largest problem with scalability within a typical environment is
the speed with which you can access information. For frequently
accessed information, using MySQL can be slow because each access of
information requires execution of the SQL query and recovery of the
information from the database. This also means that queries on tables
that are locked or blocking may delay your query and reduce the speed
of recovery of information.

`memcached' is a simple, yet highly-scalable key-based cache that
stores data and objects wherever dedicated or spare RAM is available
for very quick access by applications. To use, you run `memcached' on
one or more hosts and then use the shared cache to store
objects.Because each host's RAM is storing information, the access
speed will be much faster than having to load the information from
disk. This can provide a significant performance boost in retrieving
data versus loading the data natively from a database. Also, because
the cache is just a repository for information, you can use the cache
to store any data, including complex structures that would normally
require a significant amount of effort to create, but in a ready-to-use
format, helping to reduce the load on your MySQL servers.

The typical usage environment is to modify your application so that
information is read from the cache provided by `memcached'. If the
information isn't in `memcached', then the data is loaded from the MySQL
database and written into the cache so that future requests for the
same object benefit from the cached data.

For a typical deployment layout, see *Note ha-memcached-fig-overview::.

FIGURE GOES HERE: `memcached' overview

In the example structure, any of the clients can contact one of the
`memcached' servers to request a given key. Each client is configured
to talk to all of the servers shown in the illustration. Within the
client, when the request is made to store the information, the key used
to reference the data is hashed and this hash is then used to select
one of the `memcached' servers. The selection of the `memcached' server
takes place on the client before the server is contacted, keeping the
process lightweight.

The same algorithm is used again when a client requests the same key.
The same key will generate the same hash, and the same `memcached'
server will be selected as the source for the data. Using this method,
the cached data is spread among all of the `memcached' servers, and the
cached information is accessible from any client. The result is a
distributed, memory-based, cache that can return information,
particularly complex data and structures, much faster than natively
reading the information from the database.

The data held within a `memcached' server is never stored on disk (only
in RAM, which means there is no persistence of data), and the RAM cache
is always populated from the backing store (a MySQL database). If a
`memcached' server fails, the data can always be recovered from the
MySQL database, albeit at a slower speed than loading the information
from the cache.


File: manual.info,  Node: ha-memcached-install,  Next: ha-memcached-using,  Prev: ha-memcached,  Up: ha-memcached

16.1 Installing `memcached'
===========================

You can build and install `memcached' from the source code directly, or
you can use an existing operating system package or installation.

To install `memcached' on a RedHat, Fedora or CentOS host, use `yum':

     root-shell> yum install memcached

To install `memcached' on a Debian or Ubuntu host, use `apt-get':

     root-shell> apt-get install memcached

To install `memcached' on a Gentoo host, use `emerge':

     root-shell> emerge install memcached

To install on OpenSolaris, use the `pkg' command to install the
`SUNWmemcached' package:

     root-shell> pkg install SUNWmemcached

You may also find `memcached' in the Coolstack project. For more
details, see `http://cooltools.sunsource.net/coolstack/'.

On other Unix-based platforms, including Solaris, AIX, HP-UX and Mac OS
X, and Linux distributions not mentioned already, you will need to
install from source. For Linux, make sure you have a 2.6-based kernel,
which includes the improved `epoll' interface. For all platforms,
ensure that you have `libevent' 1.1 or higher installed. You can obtain
`libevent' from `libevent' web page
(http://www.monkey.org/~provos/libevent/).

You can obtain the source for `memcached' from `memcached' website
(http://www.danga.com/memcached).

To build `memcached', follow these steps:

  1. Extract the `memcached' source package:

          shell> gunzip -c memcached-1.2.5.tar.gz | tar xf -

  2. Change to the `memcached-1.2.5 directory:'

          shell> cd memcached-1.2.5

  3. Run `configure'

          shell> ./configure

     Some additional options you may want to specify to `configure':

        * If you want to specify a different installation directory,
          use the `--prefix' option:

               shell> ./configure --prefix=/opt

          The default is to use the `/usr/local' directory.

        * If you have installed `libevent' and `configure' cannot find
          the library, use the `--with-libevent' option to specify the
          location of the installed library.

        * To build a 64-bit version of `memcached' (which will allow
          you to use a single instance with a large RAM allocation), use
          `--enable-64bit'.

        * To enable multi-threading support in `memcached', which will
          improve the response times on servers with a heavy load, use
          `--enable-threads'.

  4. Run `make' to build `memcached':

          shell> make

  5. Run `make install' to install `memcached':

          shell> make install


File: manual.info,  Node: ha-memcached-using,  Next: ha-memcached-interfaces,  Prev: ha-memcached-install,  Up: ha-memcached

16.2 Using `memcached'
======================

* Menu:

* ha-memcached-using-deployment::  `memcached' Deployment
* ha-memcached-using-memory::    Memory allocation within `memcached'
* ha-memcached-using-namespaces::  Using namespaces
* ha-memcached-using-expiry::    Data Expiry
* ha-memcached-using-hashtypes::  `memcached' Hash Types

To start using `memcached', you must start the `memcached' service on
one or more servers.  Running `memcached' sets up the server, allocates
the memory and starts listening for connections from clients.

*Note*:

You do not need to be privileged user (`root') to run `memcached'
unless you want to listen on one of the privileged TCP/IP ports (below
1024). You must, however, use a user that has not had their memory
limits restricted using `setrlimit' or similar.

To start the server, run `memcached' as a non-privileged (i.e.
non-root) user:

     shell> memcached

If you start `memcached' as `root', use the `-u' option to specify the
user for executing `memcached':

     shell> memcached -u memcache

By default, `memcached' uses the following settings:

   * Memory allocation of 64MB

   * Listens for connections on all network interfaces, using port
     11211.

   * Supports a maximum of 1024 simultaneous connections.

To increase the amount of memory allocated for the cache, use the `-m'
option to specify the amount of RAM to be allocated (in megabytes). The
more RAM you allocate, the more data you can store and therefore the
more effective your cache will be.

*Warning*:

Do not specify a memory allocation larger than your available RAM. If
you specify too large a value, then some RAM allocated for `memcached'
will be using swap space, and not physical RAM. This may lead to delays
when storing and retrieving values, because data will be swapped to
disk, instead of storing the data directly in RAM.

You can use the output of the `vmstat' command to get the free memory,
as shown in `free' column:

     shell> vmstat
     kthr      memory            page            disk          faults      cpu
     r b w   swap  free  re  mf pi po fr de sr s1 s2 -- --   in   sy   cs us sy id
     0 0 0 5170504 3450392 2  7  2  0  0  0  4  0  0  0  0  296   54  199  0  0 100

For example, to allocate 3GB of RAM:

     shell> memcached -m 3072

On 32-bit x86 systems where you are using PAE to access memory above
the 4GB limit, you will be unable to allocate RAM beyond the maximum
process size. You can get around this by running multiple instances of
`memcached', each listening on a different port:

     shell> memcached -m 1024 -p11211
     shell> memcached -m 1024 -p11212
     shell> memcached -m 1024 -p11213

To specify a specific network interface, use the `-l' option to specify
the IP address of the desired interface:

     shell> memcached -l 192.168.0.110

To specify an alternate port to listen on, use the `-p' option:

     shell> memcached -p 18080

If you are running `memcached' on the same server as the clients, you
can disable the network interface and use a local UNIX socket using the
`-s' option:

     shell> memcached -s /tmp/memcached

Using a UNIX socket automatically disables network support, and saves
network ports (allowing more ports to be used by your web server or
other process).

To specify the maximum number of simultaneous connections to the
`memcached' service, use the `-c' option:

     shell> memcached -c 2048

You should use this option, either to reduce the number of connections
(to prevent overloading `memcached' service) or to increase the number
to make more effective use of the server running `memcached' server.

By default, `memcached' is configured to use 4 concurrent threads. The
threading improves the performance of storing and retrieving data in
the cache, using a locking system to prevent different threads
overwriting or updating the same values. You may want to increase or
decrease the number of threads, use the `-t' option:

     shell> memcached -t 8

To run `memcached' as a daemon (background) process, use the `-d'
option:

     shell> memcached -d

Typically, you would specify the full combination of options that you
want when starting `memcached', and normally provide a startup script
to handle the initialization of `memcached'. For example, the following
line starts `memcached' with a maximum of 1024MB RAM for the cache,
listening on port 11121 on the IP address 192.168.0.110, running has a
background daemon:

     shell> memcached -d -m 1024 -p 11121 -l 192.168.0.110

To ensure that `memcached' is started up on boot you should check the
init script and configuration parameters. On OpenSolaris, `memcached'
is controlled by SMF.  You can enable it by using:

     root-shell> svcadm enable memcached


File: manual.info,  Node: ha-memcached-using-deployment,  Next: ha-memcached-using-memory,  Prev: ha-memcached-using,  Up: ha-memcached-using

16.2.1 `memcached' Deployment
-----------------------------

When using `memcached' you can use a number of different potential
deployment strategies and topologies. The exact strategy you use will
depend on your application and environment. When developing a system
for deploying `memcached' within your system, you should keep in mind
the following points:

   * `memcached' is only a caching mechanism. It shouldn't be used to
     store information that you cannot otherwise afford to lose and
     then load from a different location.

   * There is no security built into the `memcached' protocol. At a
     minimum you should make sure that the servers running `memcached'
     are only accessible from inside your network, and that the network
     ports being used are blocked (using a firewall or similar). If the
     information on the `memcached' servers that is being stored is any
     sensitive, then encrypt the information before storing it in
     `memcached'.

   * `memcached' does not provide any sort of failover. Because there
     is no communication between different `memcached' instances. If an
     instance fails, your application must capable of removing it from
     the list, reloading the data and then writing data to another
     `memcached' instance.

   * Latency between the clients and the `memcached' can be a problem
     if you are using different physical machines for these tasks. If
     you find that the latency is a problem, move the `memcached'
     instances to be on the clients.

   * Key length is determined by the `memcached' server. The default
     maximum key size is 250 bytes.

   * Using a single `memcached' instance, especially for multiple
     clients, is generally a bad idea as it introduces a single point
     of failure. Instead provide at least two `memcached' instances so
     that a failure can be handled appropriately. If possible, you
     should create as many `memcached' nodes as possible. When adding
     and removing `memcached' instances from a pool, the hashing and
     distribution of key/value pairs may be affected.  For information
     on how to avoid problems, see *Note ha-memcached-using-hashtypes::.


File: manual.info,  Node: ha-memcached-using-memory,  Next: ha-memcached-using-namespaces,  Prev: ha-memcached-using-deployment,  Up: ha-memcached-using

16.2.2 Memory allocation within `memcached'
-------------------------------------------

When you first start `memcached', the memory that you have configured
is not automatically allocated.  Instead, `memcached' only starts
allocating and reserving physical memory once you start saving
information into the cache.

When you start to store data into the cache, `memcached' does not
allocate the memory for the data on an item by item basis. Instead, a
slab allocation is used to optimize memory usage and prevent memory
fragmentation when information expires from the cache.

With slab allocation, memory is reserved in blocks of 1MB. The slab is
divided up into a number of blocks of equal size. When you try to store
a value into the cache, `memcached' checks the size of the value that
you are adding to the cache and determines which slab contains the
right size allocation for the item. If a slab with the item size
already exists, the item is written to the block within the slab.

If the new item is bigger than the size of any existing blocks, then a
new slab is created, divided up into blocks of a suitable size. If an
existing slab with the right block size already exists, but there are
no free blocks, a new slab is created. If you update an existing item
with data that is larger than the existing block allocation for that
key, then the key is reallocated into a suitable slab.

For example, the default size for the smallest block is 88 bytes (40
bytes of value, and the default 48 bytes for the key and flag data). If
the size of the first item you store into the cache is less than 40
bytes, then a slab with a block size of 88 bytes is created and the
value stored.

If the size of the data that you want to store is larger than this
value, then the block size is increased by the chunk size factor until
a block size large enough to hold the value is determined. The block
size is always a function of the scale factor, rounded up to a block
size which is exactly divisible into the chunk size.

For a sample of the structure, see *Note ha-memcached-fig-slabs::.

FIGURE GOES HERE: `memcached' memory allocation

The result is that you have multiple pages allocated within the range
of memory allocated to `memcached'. Each page is 1MB in size (by
default), and will be split into different number of chunks, according
to the chunk size required to store the key/value pairs. Each instance
will have multiple pages allocated, and a page will always be created
when a new item needs to be created requiring a chunk of a particular
size.  A slab may consist of multiple pages, and each page within a
slab will contain an equal number of chunks.

The chunk size of a new slab is determined by the base chunk size
combined with the chunk size growth factor. For example, if the initial
chunks are 104 bytes in size, and the default chunk size growth factor
is used (1.25), then the next chunk size allocated would be the best
power of 2 fit for 104*1.25, or 136 bytes.

Allocating the pages in this way ensures that memory does not get
fragmented. However, depending on the distribution of the objects that
you want to store, it may lead to an inefficient distribution of the
slabs and chunks if you have significantly different sized items. For
example, having a relatively small number of items within each chunk
size may waste a lot of memory with just few chunks in each allocated
page.

You can tune the growth factor to reduce this effect by using the `-f'
command line option. This will adapt the growth factor applied to make
more effective use of the chunks and slabs allocated. For information
on how to determine the current slab allocation statistics, see *Note
ha-memcached-stats-slabs::.

If your operating system supports it, you can also start `memcached'
with the `-L' command line option. With this option enabled, it will
preallocate all the memory during startup using large memory pages.
This can improve performance by reducing the number of misses in the
CPU memory cache.


File: manual.info,  Node: ha-memcached-using-namespaces,  Next: ha-memcached-using-expiry,  Prev: ha-memcached-using-memory,  Up: ha-memcached-using

16.2.3 Using namespaces
-----------------------

The `memcached' cache is a very simple massive key/value storage
system, and as such there is no way of compartmentalizing data
automatically into different sections.  For example, if you are storing
information by the unique ID returned from a MySQL database, then
storing the data from two different tables will run into issues because
the same ID will probably be valid in both tables.

Some interfaces provide an automated mechanism for creating
_namespaces_ when storing information into the cache. In practice,
these namespaces are merely a prefix before a given ID that is applied
every time a value is stored or retrieve from the cache.

You can implement the same basic principle by using keys that describe
the object and the unique identifier within the key that you supply
when the object is stored. For example, when storing user data, prefix
the ID of the user with `user:' or `user-'.

*Note*:

Using namespaces or prefixes only controls the keys stored/retrieved.
There is no security within `memcached', and therefore no way to enforce
that a particular client only accesses keys with a particular
namespace. Namespaces are only useful as a method of identifying data
and preventing corruption of key/value pairs.


File: manual.info,  Node: ha-memcached-using-expiry,  Next: ha-memcached-using-hashtypes,  Prev: ha-memcached-using-namespaces,  Up: ha-memcached-using

16.2.4 Data Expiry
------------------

There are two types of data expiry within a `memcached' instance. The
first type is applied at the point when you store a new key/value pair
into the `memcached' instance. If there is not enough space within a
suitable slab to store the value, then an existing least recently used
(LRU) object is removed (evicted) from the cache to make room for the
new item.

The LRU algorithm ensures that the object that is removed is one that
is either no longer in active use or that was used so long ago that its
data is potentially out of date or of little value.  However, in a
system where the memory allocated to `memcached' is smaller than the
number of regularly used objects required in the cache you will see a
lot of expired items being removed from the cache even though they are
in active use. You use the statistics mechanism to get a better idea of
the level of evictions (expired objects). For more information, see
*Note ha-memcached-stats::.

You can change this eviction behavior by setting the `-M' command-line
option when starting `memcached'. This option forces an error to be
returned when the memory has been exhausted, instead of automatically
evicting older data.

The second type of expiry system is an explicit mechanism that you can
set when a key/value pair is inserted into the cache, or when deleting
an item from the cache. Using an expiration time can be a useful way of
ensuring that the data in the cache is up to date and in line with your
application needs and requirements.

A typical scenario for explicitly setting the expiry time might include
caching session data for a user when accessing a website. `memcached'
uses a lazy expiry mechanism where the explicit expiry time that has
been set is compared with the current time when the object is requested.
Only objects that have not expired are returned.

You can also set the expiry time when explicitly deleting an object
from the cache. In this case, the expiry time is really a timeout and
indicates the period when any attempts to set the value for a given key
are rejected.


File: manual.info,  Node: ha-memcached-using-hashtypes,  Prev: ha-memcached-using-expiry,  Up: ha-memcached-using

16.2.5 `memcached' Hash Types
-----------------------------

The `memcached' client interface supports a number of different hashing
types that are used in multi-server configurations to determine which
host should be used when setting or getting data from a given
`memcached' instance. When you get or set a value, a hash is
constructed from the supplied key and then used to select a host from
the list of configured servers. Because the hashing mechanism uses the
supplied key as the basis for the hash, the selected server will be the
same during both set and get operations.

For example, if you have three servers, A, B, and C, and you set the
value `myid', then the `memcached' client will create a hash based on
the ID and select server B. When the same key is requested, the same
hash is generated, and the same server, B, will be selected to request
the value.

Because the hashing mechanism is part of the client interface, not the
server interface, the hashing process and selection is very fast. By
performing the hashing on the client, it also means that if you want to
access the same data by the same ID from the same list of servers but
from different client interfaces, you must use the same or compatible
hashing mechanisms. If you do not use the same hashing mechanism then
the same data may be recorded on different servers by different
interfaces, both wasting space on your `memcached' and leading to
potential differences in the information.

*Note*:

One way to use a multi-interface compatible hashing mechanism is to use
the `libmemcached' library and the associated interfaces. Because the
interfaces for the different languages (including C, Ruby, Perl and
Python) are using the same client library interface, they will always
generate the same hash code from the ID.

One issue with the client-side hashing mechanism is that when using
multiple servers and extending or shrinking the list of servers that
you have configured for use with `memcached', the resulting hash may
change. For example, if you have servers A, B, and C; the computed hash
for key `myid' may equate to server B. If you add another server, D,
into this list, then computing the hash for the same ID again may
result in the selection of server D for that key.

This means that servers B and D both contain the information for key
`myid', but there may be differences between the data held by the two
instances. A more significant problem is that you will get a much
higher number of cache-misses when retrieving data as the addition of a
new server will change the distribution of keys, and this will in turn
require rebuilding the cached data on the `memcached' instances and
require an increase in database reads.

For this reason, there are two common types of hashing algorithm,
_consistent_ and _modula_.

With _consistent_ hashing algorithms, the same key when applied to a
list of servers will always use the same server to store or retrieve
the keys, even if the list of configured servers changes. This means
that you can add and remove servers from the configure list and always
use the same server for a given key. There are two types of consistent
hashing algorithms available, Ketama and Wheel. Both types are
supported by `libmemcached', and implementations are available for PHP
and Java.

There are some limitations with any consistent hashing algorithm. When
adding servers to an existing list of configured servers, then keys
will be distributed to the new servers as part of the normal
distribution. When removing servers from the list, the keys will be
re-allocated to another server within the list, which will mean that
the cache will need to be re-populated with the information. Also, a
consistent hashing algorithm does not resolve the issue where you want
consistent selection of a server across multiple clients, but where each
client contains a different list of servers. The consistency is
enforced only within a single client.

With a _modula_ hashing algorithm, the client will select a server by
first computing the hash and then choosing a server from the list of
configured servers. As the list of servers changes, so the server
selected when using a modula hashing algorithm will also change. The
result is the behavior described above; changes to the list of servers
will mean different servers are selected when retrieving data leading
to cache misses and increase in database load as the cache is re-seeded
with information.

If you use only a single `memcached' instance for each client, or your
list of `memcached' servers configured for a client never changes, then
the selection of a hashing algorithm is irrelevant, as you will not
notice the effect.

If you change your servers regularly, or you use a common set of
servers that are shared among a large number of clients, then using a
consistent hashing algorithm should help to ensure that your cache data
is not duplicated and the data is evenly distributed.


File: manual.info,  Node: ha-memcached-interfaces,  Next: ha-memcached-stats,  Prev: ha-memcached-using,  Up: ha-memcached

16.3 `memcached' Interfaces
===========================

* Menu:

* ha-memcached-interfaces-libmemcached::  Using `libmemcached'
* ha-memcached-interfaces-perl::  Using MySQL and `memcached' with Perl
* ha-memcached-interfaces-python::  Using MySQL and `memcached' with Python
* ha-memcached-interfaces-php::  Using MySQL and `memcached' with PHP
* ha-memcached-interfaces-ruby::  Using MySQL and `memcached' with Ruby
* ha-memcached-interfaces-java::  Using MySQL and `memcached' with Java
* ha-memcached-interfaces-mysqludf::  Using the MySQL `memcached' UDFs

A number of interfaces from different languages exist for interacting
with `memcached' servers and storing and retrieving information.
Interfaces for the most common language platforms including Perl, PHP,
Python, Ruby, C and Java.

Data stored into a `memcached' server is referred to by a single string
(the key), with storage into the cache and retrieval from the cache
using the key as the reference. The cache therefore operates like a
large associative array or hash. It is not possible to structure or
otherwise organize the information stored in the cache. If you want to
store information in a structured way, you must use 'formatted' keys.

The following tips may be useful to you when using `memcached':

The general sequence for using `memcached' in any language as a caching
solution is as follows:

  1. Request the item from the cache.

  2. If the item exists, use the item data.

  3. If the item does not exist, load the data from MySQL, and store
     the value into the cache. This means the value will be available
     to the next client that requests it from the cache.

For a flow diagram of this sequence, see *Note
ha-memcached-fig-basicflow::.

FIGURE GOES HERE: Typical `memcached' usage sequence

The interface to `memcached' supports the following methods for storing
and retrieving information in the cache, and these are consistent
across all the different APIs, even though the language specific
mechanics may be different:

   * `get(key)' -- retrieves information from the cache. Returns the
     value if it exists, or `NULL', `nil', or `undefined' or the
     closest equivalent in the corresponding language, if the specified
     key does not exist.

   * `set(key, value [, expiry])' -- sets the key in the cache to the
     specified value. Note that this will either update an existing key
     if it already exists, or add a new key/value pair if the key
     doesn't exist. If the expiry time is specified, then the key will
     expire (be deleted) when the expiry time is reached. The time
     should be specified in seconds, and is taken as a relative time if
     the value is less than 30 days (30*24*60*60), or an absolute time
     (epoch) if larger than this value.

   * `add(key, value [, expiry])' -- adds the key to the cache, if the
     specified key doesn't already exist.

   * `replace(key, value [, expiry])' -- replace the `value' of the
     specified `key', only if the key already exists.

   * `delete(key [, time])' -- Deletes the `key' from the cache. If you
     supply a `time', then adding a value with the specified `key' is
     blocked for the specified period.

   * `incr(key [, value])' -- Increment the specified `key' by one or
     the specified `value'.

   * `decr(key [, value])' -- Decrement the specified `key' by one or
     the specified `value'.

   * `flush_all' -- invalidates (or expires) all the current items in
     the cache. Technically they will still exist (they are not
     deleted), but they will be silently destroyed the next time you
     try to access them.

In all implementations, most or all of these functions are duplicated
through the corresponding native language interface.

For all languages and interfaces, you should use `memcached' to store
full items, rather than simply caching single rows of information from
the database. For example, when displaying a record about an object
(invoice, user history, or blog post), all the data for the associated
entry should be loaded from the database, and compiled into the internal
structure that would normally be required by the application. You then
save the complete object into the cache.

Data cannot be stored directly, it needs to be serialized, and most
interfaces will serialize the data for you. Perl uses `Storable', PHP
uses `serialize', Python uses `cPickle' (or `Pickle') and Java uses the
`Serializable' interface. In most cases, the serialization interface
used is customizable. If you want to share data stored in `memcached'
instances between different language interfaces, consider using a common
serialization solution such as JSON (Javascript Object Notation).

A summary table showing the list of available interfaces for different
languages, supported hash types and any additional notes is provided
below.


File: manual.info,  Node: ha-memcached-interfaces-libmemcached,  Next: ha-memcached-interfaces-perl,  Prev: ha-memcached-interfaces,  Up: ha-memcached-interfaces

16.3.1 Using `libmemcached'
---------------------------

* Menu:

* ha-memcached-interfaces-libmemcached-base::  `libmemcached' Base Functions
* ha-memcached-interfaces-libmemcached-servers::  `libmemcached' Server Functions
* ha-memcached-interfaces-libmemcached-set::  `libmemcached' Set Functions
* ha-memcached-interfaces-libmemcached-get::  `libmemcached' Get Functions
* ha-memcached-interfaces-libmemcached-behaviors::  `libmemcached' Behaviors
* ha-memcached-interfaces-libmemcached-utilities::  `libmemcached' Command-line Utilities

The `libmemcached' library provides both C and C++ interfaces to
`memcached' and is also the basis for a number of different additional
API implementations, including Perl, Python and Ruby. Understanding the
core `libmemcached' functions can help when using these other
interfaces.

The C library is the most comprehensive interface library for
`memcached' and provides a wealth of functions and operational systems
not always exposed in the other interfaces not based on the
`libmemcached' library.

The different functions can be divided up according to their basic
operation. In addition to functions that interface to the core API,
there are a number of utility functions that provide extended
functionality, such as appending and prepending data.

To build and install `libmemcached', download the `libmemcached'
package, run configure, and then build and install:

     shell> tar xjf libmemcached-0.21.tar.gz
     shell> cd libmemcached-0.21
     shell> ./configure
     shell> make
     shell> make install

On many Linux operating systems, you can install the corresponding
`libmemcached' package through the usual `yum', `apt-get' or similar
commands. On OpenSolaris, use `pkg' to install the `SUNWlibmemcached'
package.

To build an application that uses the library, you need to first set
the list of servers. You can do this either by directly manipulating
the servers configured within the main `memcached_st' structure, or by
separately populating a list of servers, and then adding this list to
the `memcached_st' structure. The latter method is used in the example
below. Once the server list has been set, you can call the functions to
store or retrieve data. A simple application for setting a preset value
to localhost is provided below:

     root-shell>include <stdio.h>
     #include <string.h>
     #include <unistd.h>
     #include <libmemcached/memcached.h>

     int main(int argc, char *argv[])
     {
       memcached_server_st *servers = NULL;
       memcached_st *memc;
       memcached_return rc;
       char *key= "keystring";
       char *value= "keyvalue";

       memcached_server_st *memcached_servers_parse (char *server_strings);
       memc= memcached_create(NULL);

       servers= memcached_server_list_append(servers, "localhost", 11211, &rc);
       rc= memcached_server_push(memc, servers);

       if (rc == MEMCACHED_SUCCESS)
         fprintf(stderr,"Added server successfully\n");
       else
         fprintf(stderr,"Couldn't add server: %s\n",memcached_strerror(memc, rc));

       rc= memcached_set(memc, key, strlen(key), value, strlen(value), (time_t)0, (uint32_t)0);

       if (rc == MEMCACHED_SUCCESS)
         fprintf(stderr,"Key stored successfully\n");
       else
         fprintf(stderr,"Couldn't store key: %s\n",memcached_strerror(memc, rc));

       return 0;
     }

You can test the success of an operation by using the return value, or
populated result code, for a given function. The value will always be
set to `MEMCACHED_SUCCESS' if the operation succeeded. In the event of
a failure, use the `memcached_strerror()' function to translate the
result code into a printable string.

To build the application, you must specify the `memcached' library:

     shell> gcc -o memc_basic memc_basic.c -lmemcached

Running the above sample application, after starting a `memcached'
server, should return a success message:

     shell> memc_basic
     Added server successfully
     Key stored successfully


File: manual.info,  Node: ha-memcached-interfaces-libmemcached-base,  Next: ha-memcached-interfaces-libmemcached-servers,  Prev: ha-memcached-interfaces-libmemcached,  Up: ha-memcached-interfaces-libmemcached

16.3.1.1 `libmemcached' Base Functions
......................................

The base `libmemcached' functions allow you to create, destroy and
clone the main `memcached_st' structure that is used to interface to
the `memcached' servers. The main functions are defined below:

     memcached_st *memcached_create (memcached_st *ptr);

Creates a new `memcached_st' structure for use with the other
`libmemcached' API functions. You can supply an existing, static,
`memcached_st' structure, or `NULL' to have a new structured allocated.
Returns a pointer to the created structure, or `NULL' on failure.

     void memcached_free (memcached_st *ptr);

Free the structure and memory allocated to a previously created
`memcached_st' structure.

     memcached_st *memcached_clone(memcached_st *clone, memcached_st *source);

Clone an existing `memcached' structure from the specified `source',
copying the defaults and list of servers defined in the structure.


File: manual.info,  Node: ha-memcached-interfaces-libmemcached-servers,  Next: ha-memcached-interfaces-libmemcached-set,  Prev: ha-memcached-interfaces-libmemcached-base,  Up: ha-memcached-interfaces-libmemcached

16.3.1.2 `libmemcached' Server Functions
........................................

The `libmemcached' API uses a list of servers, stored within the
`memcached_server_st' structure, to act as the list of servers used by
the rest of the functions. To use `memcached', you first create the
server list, and then apply the list of servers to a valid
`libmemcached' object.

Because the list of servers, and the list of servers within an active
`libmemcached' object can be manipulated separately, you can update and
manage server lists while an active `libmemcached' interface is running.

The functions for manipulating the list of servers within a
`memcached_st' structure are given below:

     memcached_return
                memcached_server_add (memcached_st *ptr,
                                      char *hostname,
                                      unsigned int port);

Add a server, using the given `hostname' and `port' into the
`memcached_st' structure given in `ptr'.

     memcached_return
                memcached_server_add_unix_socket (memcached_st *ptr,
                                                  char *socket);

Add a Unix socket to the list of servers configured in the
`memcached_st' structure.

     unsigned int memcached_server_count (memcached_st *ptr);

Return a count of the number of configured servers within the
`memcached_st' structure.

     memcached_server_st *
                memcached_server_list (memcached_st *ptr);

Returns an array of all the defined hosts within a `memcached_st'
structure.

     memcached_return
                memcached_server_push (memcached_st *ptr,
                                       memcached_server_st *list);

Pushes an existing list of servers onto list of servers configured for
a current `memcached_st' structure. This adds servers to the end of the
existing list, and duplicates are not checked.

The `memcached_server_st' structure can be used to create a list of
`memcached' servers which can then be applied individually to
`memcached_st' structures.

     memcached_server_st *
                memcached_server_list_append (memcached_server_st *ptr,
                                              char *hostname,
                                              unsigned int port,
                                              memcached_return *error);

Add a server, with `hostname' and `port', to the server list in `ptr'.
The result code is handled by the `error' argument, which should point
to an existing `memcached_return' variable. The function returns a
pointer to the returned list.

      unsigned int memcached_server_list_count (memcached_server_st *ptr);

Return the number of the servers in the server list.

     void memcached_server_list_free (memcached_server_st *ptr);

Free up the memory associated with a server list.

     memcached_server_st *memcached_servers_parse (char *server_strings);

Parses a string containing a list of servers, where individual servers
are separated by a comma and/or space, and where individual servers are
of the form `server[:port]'. The return value is a server list
structure.


File: manual.info,  Node: ha-memcached-interfaces-libmemcached-set,  Next: ha-memcached-interfaces-libmemcached-get,  Prev: ha-memcached-interfaces-libmemcached-servers,  Up: ha-memcached-interfaces-libmemcached

16.3.1.3 `libmemcached' Set Functions
.....................................

The set related functions within `libmemcached' provide the same
functionality as the core functions supported by the `memcached'
protocol. The full definition for the different functions is the same
for all the base functions (add, replace, prepend, append). For
example, the function definition for `memcached_set()' is:

     memcached_return
                memcached_set (memcached_st *ptr,
                               const char *key,
                               size_t key_length,
                               const char *value,
                               size_t value_length,
                               time_t expiration,
                               uint32_t flags);

The `ptr' is the `memcached_st' structure. The `key' and `key_length'
define the key name and length, and `value' and `value_length' the
corresponding value and length. You can also set the expiration and
optional flags. For more information, see *Note
ha-memcached-interfaces-libmemcached-behaviors::.

The table below outlines the remainder of the set-related functions.

`libmemcached' Function              Equivalent to
`memcached_set(memc, key,            Generic `set()' operation.
key_length, value, value_length,     
expiration, flags)'                  
`memcached_add(memc, key,            Generic `add()' function.
key_length, value, value_length,     
expiration, flags)'                  
`memcached_replace(memc, key,        Generic `replace()'.
key_length, value, value_length,     
expiration, flags)'                  
`memcached_prepend(memc, key,        Prepends the specified `value'
key_length, value, value_length,     before the current value of the
expiration, flags)'                  specified `key'.
`memcached_append(memc, key,         Appends the specified `value' after
key_length, value, value_length,     the current value of the specified
expiration, flags)'                  `key'.
`memcached_cas(memc, key,            Overwrites the data for a given key
key_length, value, value_length,     as long as the corresponding `cas'
expiration, flags, cas)'             value is still the same within the
                                     server.
`memcached_set_by_key(memc,          Similar to the generic `set()', but
master_key, master_key_length, key,  has the option of an additional
key_length, value, value_length,     master key that can be used to
expiration, flags)'                  identify an individual server.
`memcached_add_by_key(memc,          Similar to the generic `add()', but
master_key, master_key_length, key,  has the option of an additional
key_length, value, value_length,     master key that can be used to
expiration, flags)'                  identify an individual server.
`memcached_replace_by_key(memc,      Similar to the generic `replace()',
master_key, master_key_length, key,  but has the option of an additional
key_length, value, value_length,     master key that can be used to
expiration, flags)'                  identify an individual server.
`memcached_prepend_by_key(memc,      Similar to the
master_key, master_key_length, key,  `memcached_prepend()', but has the
key_length, value, value_length,     option of an additional master key
expiration, flags)'                  that can be used to identify an
                                     individual server.
`memcached_append_by_key(memc,       Similar to the
master_key, master_key_length, key,  `memcached_append()', but has the
key_length, value, value_length,     option of an additional master key
expiration, flags)'                  that can be used to identify an
                                     individual server.
`memcached_cas_by_key(memc,          Similar to the `memcached_cas()',
master_key, master_key_length, key,  but has the option of an additional
key_length, value, value_length,     master key that can be used to
expiration, flags)'                  identify an individual server.

The `by_key' methods add two further arguments, the master key, to be
used and applied during the hashing stage for selecting the servers.
You can see this in the definition below:

     memcached_return
                memcached_set_by_key(memcached_st *ptr,
                                     const char *master_key,
                                     size_t master_key_length,
                                     const char *key,
                                     size_t key_length,
                                     const char *value,
                                     size_t value_length,
                                     time_t expiration,
                                     uint32_t flags);

All the functions return a value of type `memcached_return', which you
can compare against the `MEMCACHED_SUCCESS' constant.


File: manual.info,  Node: ha-memcached-interfaces-libmemcached-get,  Next: ha-memcached-interfaces-libmemcached-behaviors,  Prev: ha-memcached-interfaces-libmemcached-set,  Up: ha-memcached-interfaces-libmemcached

16.3.1.4 `libmemcached' Get Functions
.....................................

The `libmemcached' functions provide both direct access to a single
item, and a multiple-key request mechanism that provides much faster
responses when fetching a large number of keys simultaneously.

The main get-style function, which is equivalent to the generic `get()'
is `memcached_get()'. The functions a string pointer to the returned
value for a corresponding key.

     char *memcached_get (memcached_st *ptr,
                          const char *key, size_t key_length,
                          size_t *value_length,
                          uint32_t *flags,
                          memcached_return *error);

A multi-key get, `memcached_mget()', is also available. Using a
multiple key get operation is much quicker to do in one block than
retrieving the key values with individual calls to `memcached_get()'. To
start the multi-key get, you need to call `memcached_mget()':

     memcached_return
              memcached_mget (memcached_st *ptr,
                              char **keys, size_t *key_length,
                              unsigned int number_of_keys);

The return value is the success of the operation. The `keys' parameter
should be an array of strings containing the keys, and `key_length' an
array containing the length of each corresponding key.
`number_of_keys' is the number of keys supplied in the array.

To fetch the individual values, you need to use `memcached_fetch()' to
get each corresponding value.

     char *memcached_fetch (memcached_st *ptr,
                              const char *key, size_t *key_length,
                              size_t *value_length,
                              uint32_t *flags,
                              memcached_return *error);

The function returns the key value, with the `key', `key_length' and
`value_length' parameters being populated with the corresponding key
and length information. The function returns `NULL' when there are no
more values to be returned. A full example, including the populating of
the key data and the return of the information is provided below.

     root-shell>include <stdio.h>
     #include <sstring.h>
     #include <unistd.h>
     #include <libmemcached/memcached.h>

     int main(int argc, char *argv[])
     {
       memcached_server_st *servers = NULL;
       memcached_st *memc;
       memcached_return rc;
       char *keys[]= {"huey", "dewey", "louie"};
       size_t key_length[3];
       char *values[]= {"red", "blue", "green"};
       size_t value_length[3];
       unsigned int x;
       uint32_t flags;

       char return_key[MEMCACHED_MAX_KEY];
       size_t return_key_length;
       char *return_value;
       size_t return_value_length;

       memc= memcached_create(NULL);

       servers= memcached_server_list_append(servers, "localhost", 11211, &rc);
       rc= memcached_server_push(memc, servers);

       if (rc == MEMCACHED_SUCCESS)
         fprintf(stderr,"Added server successfully\n");
       else
         fprintf(stderr,"Couldn't add server: %s\n",memcached_strerror(memc, rc));

       for(x= 0; x < 3; x++)
         {
           key_length[x] = strlen(keys[x]);
           value_length[x] = strlen(values[x]);

           rc= memcached_set(memc, keys[x], key_length[x], values[x],
                             value_length[x], (time_t)0, (uint32_t)0);
           if (rc == MEMCACHED_SUCCESS)
             fprintf(stderr,"Key %s stored successfully\n",keys[x]);
           else
             fprintf(stderr,"Couldn't store key: %s\n",memcached_strerror(memc, rc));
         }

       rc= memcached_mget(memc, keys, key_length, 3);

       if (rc == MEMCACHED_SUCCESS)
         {
           while ((return_value= memcached_fetch(memc, return_key, &return_key_length,
                                                 &return_value_length, &flags, &rc)) != NULL)
             {
               if (rc == MEMCACHED_SUCCESS)
                 {
                   fprintf(stderr,"Key %s returned %s\n",return_key, return_value);
                 }
             }
         }

       return 0;
     }

Running the above application:

     shell> memc_multi_fetch
     Added server successfully
     Key huey stored successfully
     Key dewey stored successfully
     Key louie stored successfully
     Key huey returned red
     Key dewey returned blue
     Key louie returned green


File: manual.info,  Node: ha-memcached-interfaces-libmemcached-behaviors,  Next: ha-memcached-interfaces-libmemcached-utilities,  Prev: ha-memcached-interfaces-libmemcached-get,  Up: ha-memcached-interfaces-libmemcached

16.3.1.5 `libmemcached' Behaviors
.................................

The behavior of `libmemcached' can be modified by setting one or more
behavior flags. These can either be set globally, or they can be
applied during the call to individual functions. Some behaviors also
accept an additional setting, such as the hashing mechanism used when
selecting servers.

To set global behaviors:

     memcached_return
                memcached_behavior_set (memcached_st *ptr,
                                        memcached_behavior flag,
                                        uint64_t data);

To get the current behavior setting:

     uint64_t
                memcached_behavior_get (memcached_st *ptr,
                                        memcached_behavior flag);

Behavior                      Description
`MEMCACHED_BEHAVIOR_NO_BLOCK' Caused `libmemcached' to use asynchronous
                              I/O.
`MEMCACHED_BEHAVIOR_TCP_NODELAY'Turns on no-delay for network sockets.
`MEMCACHED_BEHAVIOR_HASH'     Without a value, sets the default hashing
                              algorithm for keys to use MD5.  Other
                              valid values include
                              `MEMCACHED_HASH_DEFAULT',
                              `MEMCACHED_HASH_MD5', `MEMCACHED_HASH_CRC',
                              `MEMCACHED_HASH_FNV1_64',
                              `MEMCACHED_HASH_FNV1A_64',
                              `MEMCACHED_HASH_FNV1_32', and
                              `MEMCACHED_HASH_FNV1A_32'.
`MEMCACHED_BEHAVIOR_DISTRIBUTION'Changes the method of selecting the server
                              used to store a given value.  The default
                              method is `MEMCACHED_DISTRIBUTION_MODULA'.
                              You can enable consistent hashing by
                              setting
                              `MEMCACHED_DISTRIBUTION_CONSISTENT'.
                              `MEMCACHED_DISTRIBUTION_CONSISTENT' is an
                              alias for the value
                              `MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA'.
`MEMCACHED_BEHAVIOR_CACHE_LOOKUPS'Cache the lookups made to the DNS service.
                              This can improve the performance if you
                              are using names instead of IP addresses
                              for individual hosts.
`MEMCACHED_BEHAVIOR_SUPPORT_CAS'Support CAS operations. By default, this
                              is disabled because it imposes a
                              performance penalty.
`MEMCACHED_BEHAVIOR_KETAMA'   Sets the default distribution to
                              `MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA'
                              and the hash to `MEMCACHED_HASH_MD5'.
`MEMCACHED_BEHAVIOR_POLL_TIMEOUT'Modify the timeout value used by `poll()'.
                              You should supply a `signed int' pointer
                              for the timeout value.
`MEMCACHED_BEHAVIOR_BUFFER_REQUESTS'Buffers IO requests instead of them being
                              sent. A get operation, or closing the
                              connection will cause the data to be
                              flushed.
`MEMCACHED_BEHAVIOR_VERIFY_KEY'Forces `libmemcached' to verify that a
                              specified key is valid.
`MEMCACHED_BEHAVIOR_SORT_HOSTS'If set, hosts added to the list of
                              configured hosts for a `memcached_st'
                              structure will placed into the host list
                              in sorted order. This will break
                              consistent hashing if that behavior has
                              been enabled.
`MEMCACHED_BEHAVIOR_CONNECT_TIMEOUT'In non-blocking mode this changes the
                              value of the timeout during socket
                              connection.


File: manual.info,  Node: ha-memcached-interfaces-libmemcached-utilities,  Prev: ha-memcached-interfaces-libmemcached-behaviors,  Up: ha-memcached-interfaces-libmemcached

16.3.1.6 `libmemcached' Command-line Utilities
..............................................

In addition to the main C library interface, `libmemcached' also
includes a number of command line utilities that can be useful when
working with and debugging `memcached' applications.

All of the command line tools accept a number of arguments, the most
critical of which is `servers', which specifies the list of servers to
connect to when returning information.

The main tools are:

   * `memcat' -- display the value for each ID given on the command
     line:

          shell> memcat --servers=localhost hwkey
          Hello world

   * `memcp' -- copy the contents of a file into the cache, using the
     file names as the key:

          shell> echo "Hello World" > hwkey
          shell> memcp --servers=localhost hwkey
          shell> memcat --servers=localhost hwkey
          Hello world

   * `memrm' -- remove an item from the cache:

          shell> memcat --servers=localhost hwkey
          Hello world
          shell> memrm --servers=localhost hwkey
          shell> memcat --servers=localhost hwkey

   * `memslap' -- test the load on one or more `memcached' servers,
     simulating get/set and multiple client operations. For example, you
     can simulate the load of 100 clients performing get operations:

          shell> memslap --servers=localhost --concurrency=100 --flush --test=get
          memslap --servers=localhost --concurrency=100 --flush --test=get	Threads connecting to servers 100
          	Took 13.571 seconds to read data

   * `memflush' -- flush (empty) the contents of the `memcached' cache.

          shell> memflush --servers=localhost


File: manual.info,  Node: ha-memcached-interfaces-perl,  Next: ha-memcached-interfaces-python,  Prev: ha-memcached-interfaces-libmemcached,  Up: ha-memcached-interfaces

16.3.2 Using MySQL and `memcached' with Perl
--------------------------------------------

The `Cache::Memcached' module provides a native interface to the
Memcache protocol, and provides support for the core functions offered
by `memcached'. You should install the module using your hosts native
package management system. Alternatively, you can install the module
using `CPAN':

     root-shell> perl -MCPAN -e 'install Cache::Memcached'

To use `memcached' from Perl through `Cache::Memcached' module, you
first need to create a new `Cache::Memcached' object that defines the
list of servers and other parameters for the connection. The only
argument is a hash containing the options for the cache interface. For
example, to create a new instance that uses three `memcached' servers:

     use Cache::Memcached;

     my $cache = new Cache::Memcached {
         'servers' => [
             '192.168.0.100:11211',
             '192.168.0.101:11211',
             '192.168.0.102:11211',
     	],
     };

*Note*:

When using the `Cache::Memcached' interface with multiple servers, the
API automatically performs certain operations across all the servers in
the group. For example, getting statistical information through
`Cache::Memcached' returns a hash that contains data on a host by host
basis, as well as generalized statistics for all the servers in the
group.

You can set additional properties on the cache object instance when it
is created by specifying the option as part of the option hash.
Alternatively, you can use a corresponding method on the instance:

   * `servers' or method `set_servers()' -- specifies the list of the
     servers to be used. The servers list should be a reference to an
     array of servers, with each element as the address and port number
     combination (separated by a colon).  You can also specify a local
     connection through a UNIX socket (for example
     `/tmp/sock/memcached'). You can also specify the server with a
     weight (indicating how much more frequently the server should be
     used during hashing) by specifying an array reference with the
     `memcached' server instance and a weight number. Higher numbers
     give higher priority.

   * `compress_threshold' or method `set_compress_threshold()'--
     specifies the threshold when values are compressed. Values larger
     than the specified number are automatically compressed (using
     `zlib') during storage and retrieval.

   * `no_rehash' or method `set_norehash()' -- disables finding a new
     server if the original choice is unavailable.

   * `readonly' or method `set_readonly()'-- disables writes to the
     `memcached' servers.

Once the `Cache::Memcached' object instance has been configured you can
use the `set()' and `get()' methods to store and retrieve information
from the `memcached' servers.  Objects stored in the cache are
automatically serialized and deserialized using the `Storable' module.

The `Cache::Memcached' interface supports the following methods for
storing/retrieving data, and relate to the generic methods as shown in
the table.

`Cache::Memcached' Function          Equivalent to
`get()'                              Generic `get()'
`get_multi(keys)'                    Gets multiple `keys' from memcache
                                     using just one query. Returns a
                                     hash reference of key/value pairs.
`set()'                              Generic `set()'
`add()'                              Generic `add()'
`replace()'                          Generic `replace()'
`delete()'                           Generic `delete()'
`incr()'                             Generic `incr()'
`decr()'                             Generic `decr()'

Below is a complete example for using `memcached' with Perl and the
`Cache::Memcached' module:

     root-shell>!/usr/bin/perl

     use Cache::Memcached;
     use DBI;
     use Data::Dumper;

     # Configure the memcached server

     my $cache = new Cache::Memcached {
         'servers' => [
                        'localhost:11211',
                        ],
         };

     # Get the film name from the command line
     # memcached keys must not contain spaces, so create
     # a key name by replacing spaces with underscores

     my $filmname = shift or die "Must specify the film name\n";
     my $filmkey = $filmname;
     $filmkey =~ s/ /_/;

     # Load the data from the cache

     my $filmdata = $cache->get($filmkey);

     # If the data wasn't in the cache, then we load it from the database

     if (!defined($filmdata))
     {
         $filmdata = load_filmdata($filmname);

         if (defined($filmdata))
         {

     # Set the data into the cache, using the key

     	if ($cache->set($filmkey,$filmdata))
             {
                 print STDERR "Film data loaded from database and cached\n";
             }
             else
             {
                 print STDERR "Couldn't store to cache\n";
     	}
         }
         else
         {
          	die "Couldn't find $filmname\n";
         }
     }
     else
     {
         print STDERR "Film data loaded from Memcached\n";
     }

     sub load_filmdata
     {
         my ($filmname) = @_;

         my $dsn = "DBI:mysql:database=sakila;host=localhost;port=3306";

         $dbh = DBI->connect($dsn, 'sakila','password');

         my ($filmbase) = $dbh->selectrow_hashref(sprintf('select * from film where title = %s',
                                                          $dbh->quote($filmname)));

         if (!defined($filmname))
         {
          	return (undef);
         }

         $filmbase->{stars} =
     	$dbh->selectall_arrayref(sprintf('select concat(first_name," ",last_name) ' .
                                              'from film_actor left join (actor) ' .
                                              'on (film_actor.actor_id = actor.actor_id) ' .
                                              ' where film_id=%s',
                                              $dbh->quote($filmbase->{film_id})));

         return($filmbase);
     }

The example uses the Sakila database, obtaining film data from the
database and writing a composite record of the film and actors to
memcache. When calling it for a film does not exist, you should get
this result:

     shell> memcached-sakila.pl "ROCK INSTINCT"
     Film data loaded from database and cached

When accessing a film that has already been added to the cache:

     shell> memcached-sakila.pl "ROCK INSTINCT"
     Film data loaded from Memcached


File: manual.info,  Node: ha-memcached-interfaces-python,  Next: ha-memcached-interfaces-php,  Prev: ha-memcached-interfaces-perl,  Up: ha-memcached-interfaces

16.3.3 Using MySQL and `memcached' with Python
----------------------------------------------

The Python `memcache' module interfaces to `memcached' servers, and is
written in pure python (i.e. without using one of the C APIs). You can
download and install a copy from Python Memcached
(http://www.tummy.com/Community/software/python-memcached/).

To install, download the package and then run the Python installer:

     python setup.py install
     running install
     running bdist_egg
     running egg_info
     creating python_memcached.egg-info
     ...
     removing 'build/bdist.linux-x86_64/egg' (and everything under it)
     Processing python_memcached-1.43-py2.4.egg
     creating /usr/lib64/python2.4/site-packages/python_memcached-1.43-py2.4.egg
     Extracting python_memcached-1.43-py2.4.egg to /usr/lib64/python2.4/site-packages
     Adding python-memcached 1.43 to easy-install.pth file

     Installed /usr/lib64/python2.4/site-packages/python_memcached-1.43-py2.4.egg
     Processing dependencies for python-memcached==1.43
     Finished processing dependencies for python-memcached==1.43

Once installed, the `memcache' module provides a class-based interface
to your `memcached' servers. Serialization of Python structures is
handled by using the Python `cPickle' or `pickle' modules.

To create a new `memcache' interface, import the `memcache' module and
create a new instance of the `memcache.Client' class:

     import memcache
     memc = memcache.Client(['127.0.0.1:11211'])

The first argument should be an array of strings containing the server
and port number for each `memcached' instance you want to use. You can
enable debugging by setting the optional `debug' parameter to 1.

By default, the hashing mechanism used is `crc32'. This provides a
basic module hashing algorithm for selecting among multiple servers.
You can change the function used by setting the value of
`memcache.serverHashFunction' to the alternate function you want to
use. For example:

     from zlib import adler32
     memcache.serverHashFunction = adler32

Once you have defined the servers to use within the `memcache'
instance, the core functions provide the same functionality as in the
generic interface specification. A summary of the supported functions
is provided in the table below.

Python `memcache' Function           Equivalent to
`get()'                              Generic `get()'
`get_multi(keys)'                    Gets multiple values from the
                                     supplied array of `keys'.  Returns
                                     a hash reference of key/value pairs.
`set()'                              Generic `set()'
`set_multi(dict [, expiry [,         Sets multiple key/value pairs from
key_prefix]])'                       the supplied `dict'.
`add()'                              Generic `add()'
`replace()'                          Generic `replace()'
`prepend(key, value [, expiry])'     Prepends the supplied `value' to
                                     the value of the existing `key'.
`append(key, value [, expiry[)'      Appends the supplied `value' to the
                                     value of the existing `key'.
`delete()'                           Generic `delete()'
`delete_multi(keys [, expiry [,      Deletes all the keys from the hash
key_prefix]] )'                      matching each string in the array
                                     `keys'.
`incr()'                             Generic `incr()'
`decr()'                             Generic `decr()'

*Note*:

Within the Python `memcache' module, all the `*_multi()'functions
support an optional `key_prefix' parameter. If supplied, then the
string is used as a prefix to all key lookups. For example, if you call:

     memc.get_multi(['a','b'], key_prefix='users:')

The function will retrieve the keys `users:a' and `users:b' from the
servers.

An example showing the storage and retrieval of information to a
`memcache' instance, loading the raw data from MySQL, is shown below:

     import sys
     import MySQLdb
     import memcache

     memc = memcache.Client(['127.0.0.1:11211'], debug=1);

     try:
         conn = MySQLdb.connect (host = "localhost",
                                 user = "sakila",
                                 passwd = "password",
                                 db = "sakila")
     except MySQLdb.Error, e:
          print "Error %d: %s" % (e.args[0], e.args[1])
          sys.exit (1)

     popularfilms = memc.get('top5films')

     if not popularfilms:
         cursor = conn.cursor()
         cursor.execute('select film_id,title from film order by rental_rate desc limit 5')
         rows = cursor.fetchall()
         memc.set('top5films',rows,60)
         print "Updated memcached with MySQL data"
     else:
         print "Loaded data from memcached"
         for row in popularfilms:
             print "%s, %s" % (row[0], row[1])

When executed for the first time, the data is loaded from the MySQL
database and stored to the `memcached' server.

     shell> python memc_python.py
     Updated memcached with MySQL data

The data is automatically serialized using `cPickle'/`pickle'. This
means when you load the data back from `memcached', you can use the
object directly. In the example above, the information stored to
`memcached' is in the form of rows from a Python DB cursor. When
accessing the information (within the 60 second expiry time), the data
is loaded from `memcached' and dumped:

     shell> python memc_python.py
     Loaded data from memcached
     2, ACE GOLDFINGER
     7, AIRPLANE SIERRA
     8, AIRPORT POLLOCK
     10, ALADDIN CALENDAR
     13, ALI FOREVER

The serialization and deserialization happens automatically, but be
aware that serialization of Python data may be incompatible with other
interfaces and languages. You can change the serialization module used
during initialization, for example to use JSON, which will be more
easily exchanged.


File: manual.info,  Node: ha-memcached-interfaces-php,  Next: ha-memcached-interfaces-ruby,  Prev: ha-memcached-interfaces-python,  Up: ha-memcached-interfaces

16.3.4 Using MySQL and `memcached' with PHP
-------------------------------------------

PHP provides support for the Memcache functions through a PECL
extension. To enable the PHP `memcache' extensions, you must build PHP
using the `--enable-memcache' option to `configure' when building from
source.

If you are installing on a RedHat based server, you can install the
`php-pecl-memcache' RPM:

     root-shell> yum --install php-pecl-memcache

On Debian based distributions, use the `php-memcache' package.

You can set global runtime configuration options by specifying the
values in the following table within your `php.ini' file.

Configuration option      Default        Description
`memcache.allow_failover' 1              Specifies whether another
                                         server in the list should be
                                         queried if the first server
                                         selected fails.
`memcache.max_failover_attempts'20             Specifies the number of servers
                                         to try before returning a
                                         failure.
`memcache.chunk_size'     8192           Defines the size of network
                                         chunks used to exchange data
                                         with the `memcached' server.
`memcache.default_port'   11211          Defines the default port to use
                                         when communicating with the
                                         `memcached' servers.
`memcache.hash_strategy'  standard       Specifies which hash strategy
                                         to use. Set to `consistent' to
                                         allow servers to be added or
                                         removed from the pool without
                                         causing the keys to be remapped
                                         to other servers. When set to
                                         `standard', an older (modula)
                                         strategy is used that
                                         potentially uses different
                                         servers for storage.
`memcache.hash_function'  crc32          Specifies which function to use
                                         when mapping keys to servers.
                                         `crc32' uses the standard CRC32
                                         hash.  `fnv' uses the FNV-1a
                                         hashing algorithm.

To create a connection to a `memcached' server, you need to create a
new `Memcache' object and then specifying the connection options. For
example:

     <?php

     $cache = new Memcache;
     $cache->connect('localhost',11121);
     ?>

This opens an immediate connection to the specified server.

To use multiple `memcached' servers, you need to add servers to the
memcache object using `addServer()':

     bool Memcache::addServer ( string $host [, int $port [, bool $persistent
                      [, int $weight [, int $timeout [, int $retry_interval
                      [, bool $status [, callback $failure_callback
                      ]]]]]]] )

The server management mechanism within the `php-memcache' module is a
critical part of the interface as it controls the main interface to the
`memcached' instances and how the different instances are selected
through the hashing mechanism.

To create a simple connection to two `memcached' instances:

     <?php

     $cache = new Memcache;
     $cache->addServer('192.168.0.100',11211);
     $cache->addServer('192.168.0.101',11211);
     ?>

In this scenario the instance connection is not explicitly opened, but
only opened when you try to store or retrieve a value. You can enable
persistent connections to `memcached' instances by setting the
`$persistent' argument to true. This is the default setting, and will
cause the connections to remain open.

To help control the distribution of keys to different instances, you
should use the global `memcache.hash_strategy' setting. This sets the
hashing mechanism used to select. You can also add an additional weight
to each server, which effectively increases the number of times the
instance entry appears in the instance list, therefore increasing the
likelihood of the instance being chosen over other instances. To set
the weight, set the value of the `$weight' argument to more than one.

The functions for setting and retrieving information are identical to
the generic functional interface offered by `memcached', as shown in
this table.

PECL `memcache' Function             Equivalent to
`get()'                              Generic `get()'
`set()'                              Generic `set()'
`add()'                              Generic `add()'
`replace()'                          Generic `replace()'
`delete()'                           Generic `delete()'
`increment()'                        Generic `incr()'
`decrement()'                        Generic `decr()'

A full example of the PECL `memcache' interface is provided below. The
code loads film data from the Sakila database when the user provides a
film name. The data stored into the `memcached' instance is recorded as
a `mysqli' result row, and the API automatically serializes the
information for you.

     <?php

     $memc = new Memcache;
     $memc->addServer('localhost','11211');
     ?>

     <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
     <head>
      <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
      <title>Simple Memcache Lookup</title>
     </head>
     <body>
     <form method="post">
       <p><b>Film</b>: <input type="text" size="20" name="film"></p>
     <input type="submit">
     </form>
     <hr/>

     <?php

       echo "Loading data...\n";

     $value = $memc->get($_REQUEST['film']);

     if ($value)
       {
         printf("<p>Film data for %s loaded from memcache</p>",$value['title']);

         foreach (array_keys($value) as $key)
           {
     	printf("<p><b>%s</b>: %s</p>",$key, $value[$key]);
           }
       }
      else
        {
          $con = new mysqli('localhost','sakila','password','sakila') or
            die ("<h1>Database problem</h1>" . mysqli_connect_error());

          $result = $con->query(sprintf('select * from film where title ="%s"',$_REQUEST['film']));

          $row = $result->fetch_array(MYSQLI_ASSOC);

          $memc->set($row['title'],$row);

          printf("<p>Loaded %s from MySQL</p>",$row['title']);
        }

     ?>

With PHP, the connections to the `memcached' instances are kept open as
long as the PHP and associated Apache instance remain running. When
adding a removing servers from the list in a running instance (for
example, when starting another script that mentions additional
servers), the connections will be shared, but the script will only
select among the instances explicitly configured within the script.

To ensure that changes to the server list within a script do not cause
problems, make sure to use the consistent hashing mechanism.


File: manual.info,  Node: ha-memcached-interfaces-ruby,  Next: ha-memcached-interfaces-java,  Prev: ha-memcached-interfaces-php,  Up: ha-memcached-interfaces

16.3.5 Using MySQL and `memcached' with Ruby
--------------------------------------------

There are a number of different modules for interfacing to `memcached'
within Ruby. The `Ruby-MemCache' client library provides a native
interface to `memcached' that does not require any external libraries,
such as `libmemcached'. You can obtain the installer package from
`http://www.deveiate.org/projects/RMemCache'.

To install, extract the package and then run `install.rb':

     shell> install.rb

If you have RubyGems, you can install the `Ruby-MemCache' gem:

     shell> gem install Ruby-MemCache
     Bulk updating Gem source index for: http://gems.rubyforge.org
     Install required dependency io-reactor? [Yn]  y
     Successfully installed Ruby-MemCache-0.0.1
     Successfully installed io-reactor-0.05
     Installing ri documentation for io-reactor-0.05...
     Installing RDoc documentation for io-reactor-0.05...

To use a `memcached' instance from within Ruby, create a new instance
of the `MemCache' object.

     require 'memcache'
     memc = MemCache::new '192.168.0.100:11211'

You can add a weight to each server to increase the likelihood of the
server being selected during hashing by appending the weight count to
the server hostname/port string:

     require 'memcache'
     memc = MemCache::new '192.168.0.100:11211:3'

To add servers to an existing list, you can append them directly to the
`MemCache' object:

     memc += ["192.168.0.101:11211"]

To set data into the cache, you can just assign a value to a key within
the new cache object, which works just like a standard Ruby hash object:

     memc["key"] = "value"

Or to retrieve the value:

     print memc["key"]

For more explicit actions, you can use the method interface, which
mimics the main `memcached' API functions, as summarized in the table
below.

Ruby `MemCache' Method               Equivalent to
`get()'                              Generic `get()'
`get_hash(keys)'                     Get the values of multiple `keys',
                                     returning the information as a hash
                                     of the keys and their values.
`set()'                              Generic `set()'
`set_many(pairs)'                    Set the values of the keys and
                                     values in the hash `pairs'.
`add()'                              Generic `add()'
`replace()'                          Generic `replace()'
`delete()'                           Generic `delete()'
`incr()'                             Generic `incr()'
`decr()'                             Generic `decr()'


File: manual.info,  Node: ha-memcached-interfaces-java,  Next: ha-memcached-interfaces-mysqludf,  Prev: ha-memcached-interfaces-ruby,  Up: ha-memcached-interfaces

16.3.6 Using MySQL and `memcached' with Java
--------------------------------------------

The `com.danga.MemCached' class within Java provides a native interface
to `memcached' instances. You can obtain the client from
`http://whalin.com/memcached/'. The Java class uses hashes that are
compatible with `libmemcached', so you can mix and match Java and
`libmemcached' applications accessing the same `memcached' instances.
The serialization between Java and other interfaces will not be
compatible. If this is a problem, use JSON or a similar non-binary
serialization format.

On most systems you can download the package and use the `jar'
directly. On OpenSolaris, use `pkg' to install the `SUNWmemcached-java'
package.

To use the `com.danga.MemCached' interface, you create a
`MemCachedClient' instance and then configure the list of servers by
configuring the `SockIOPool'. Through the pool specification you set up
the server list, weighting, and the connection parameters to optimized
the connections between your client and the `memcached' instances that
you configure.

Generally you can configure the `memcached' interface once within a
single class and then use this interface throughout the rest of your
application.

For example, to create a basic interface, first configure the
`MemCachedClient' and base `SockIOPool' settings:

     public class MyClass {

         protected static MemCachedClient mcc = new MemCachedClient();

         static {

             String[] servers =
                 {
                     "localhost:11211",
                 };

             Integer[] weights = { 1 };

             SockIOPool pool = SockIOPool.getInstance();

             pool.setServers( servers );
             pool.setWeights( weights );

In the above sample, the list of servers is configured by creating an
array of the `memcached' instances that you want to use. You can then
configure individual weights for each server.

The remainder of the properties for the connection are optional, but
you can set the connection numbers (initial connections, minimum
connections, maximum connections, and the idle timeout) by setting the
pool parameters:

     pool.setInitConn( 5 );
     pool.setMinConn( 5 );
     pool.setMaxConn( 250 );
     pool.setMaxIdle( 1000 * 60 * 60 * 6

Once the parameters have been configured, initialize the connection
pool:

     pool.initialize();

The pool, and the connection to your `memcached' instances should now
be ready to use.

To set the hashing algorithm used to select the server used when
storing a given key you can use `pool.setHashingAlg()':

     pool.setHashingAlg( SockIOPool.NEW_COMPAT_HASH );

Valid values ares `NEW_COMPAT_HASH', `OLD_COMPAT_HASH' and
`NATIVE_HASH' are also basic modula hashing algorithms. For a
consistent hashing algorithm, use `CONSISTENT_HASH'. These constants are
equivalent to the corresponding hash settings within `libmemcached'.

Java `com.danga.MemCached' Method    Equivalent to
`get()'                              Generic `get()'
`getMulti(keys)'                     Get the values of multiple `keys',
                                     returning the information as Hash
                                     map using `java.lang.String' for
                                     the keys and `java.lang.Object' for
                                     the corresponding values.
`set()'                              Generic `set()'
`add()'                              Generic `add()'
`replace()'                          Generic `replace()'
`delete()'                           Generic `delete()'
`incr()'                             Generic `incr()'
`decr()'                             Generic `decr()'


File: manual.info,  Node: ha-memcached-interfaces-mysqludf,  Prev: ha-memcached-interfaces-java,  Up: ha-memcached-interfaces

16.3.7 Using the MySQL `memcached' UDFs
---------------------------------------

The `memcached' MySQL User Defined Functions (UDFs) enable you to set
and retrieve objects from within MySQL 5.0 or greater.

To install the MySQL `memcached' UDFs, download the UDF package from
`http://tangent.org/586/Memcached_Functions_for_MySQL.html'.  You will
need to unpack the package and run `configure' to configure the build
process.  When running `configure', use the `--with-mysql' option and
specify the location of the `mysql_config' command. Note that you must
be running :

     shell> tar zxf memcached_functions_mysql-0.5.tar.gz
     shell> cd memcached_functions_mysql-0.5
     shell> ./configure --with-mysql-config=/usr/local/mysql/bin/mysql_config

Now build and install the functions:

     shell> make
     shell> make install

You may want to copy the MySQL `memcached' UDFs into your MySQL plugins
directory:

     shell> cp /usr/local/lib/libmemcached_functions_mysql* /usr/local/mysql/lib/mysql/plugins/

Once installed, you must initialize the function within MySQL using
`CREATE' and specifying the return value and library. For example, to
add the `memc_get()' function:

     mysql> CREATE FUNCTION memc_get RETURNS STRING SONAME "libmemcached_functions_mysql.so";

You must repeat this process for each function that you want to provide
access to within MySQL. Once you have created the association, the
information will be retained, even over restarts of the MySQL server.
You can simplify the process by using the SQL script provided in the
`memcached' UDFs package:

     shell> mysql <sql/install_functions.sql

Alternatively, if you have Perl installed, then you can use the
supplied Perl script, which will check for the existence of each
function and create the function/library association if it has not
already been defined:

     shell> utils/install.pl --silent

The `--silent' option installs everything automatically. Without this
option, the script will ask whether you want to install each of the
available functions.

The interface remains consistent with the other APIs and interfaces. To
set up a list of servers, use the `memc_servers_set()' function, which
accepts a single string containing and comma-separated list of servers:

     mysql> SELECT memc_servers_set('192.168.0.1:11211,192.168.0.2:11211');

*Note*:

The list of servers used by the `memcached' UDFs is not persistent over
restarts of the MySQL server. If the MySQL server fails, then you must
re-set the list of `memcached' servers.

To set a value, use `memc_set':

     mysql> SELECT memc_set('myid', 'myvalue');

To retrieve a stored value:

     mysql> SELECT memc_get('myid');

The list of functions supported by the UDFs, in relation to the
standard protocol functions, is shown in the table below.

MySQL `memcached' UDF Function       Equivalent to
`memc_get()'                         Generic `get()'
`memc_get_by_key(master_key, key,    Like the generic `get()', but uses
value)'                              the supplied master key to select
                                     the server to use.
`memc_set()'                         Generic `set()'
`memc_set_by_key(master_key, key,    Like the generic `set()', but uses
value)'                              the supplied master key to select
                                     the server to use.
`memc_add()'                         Generic `add()'
`memc_add_by_key(master_key, key,    Like the generic `add()', but uses
value)'                              the supplied master key to select
                                     the server to use.
`memc_replace()'                     Generic `replace()'
`memc_replace_by_key(master_key,     Like the generic `replace()', but
key, value)'                         uses the supplied master key to
                                     select the server to use.
`memc_prepend(key, value)'           Prepend the specified `value' to
                                     the current value of the specified
                                     `key'.
`memc_append(key, value)'            Append the specified `value' to the
                                     current value of the specified
                                     `key'.
`memc_delete()'                      Generic `delete()'
`memc_delete_by_key(master_key,      Like the generic `delete()', but
key, value)'                         uses the supplied master key to
                                     select the server to use.
`memc_incr()'                        Generic `incr()'
`memc_decr()'                        Generic `decr()'

The `memcached' UDFs also support the different behaviors as provided
by the `libmemcached' library. You can set these by using the
`memc_servers_behavior_set()' function. For more information on
`libmemcached' behaviors, see *Note
ha-memcached-interfaces-libmemcached::.


File: manual.info,  Node: ha-memcached-stats,  Next: ha-memcached-faq,  Prev: ha-memcached-interfaces,  Up: ha-memcached

16.4 Getting `memcached' Statistics
===================================

* Menu:

* ha-memcached-stats-general::   `memcached' General Statistics
* ha-memcached-stats-slabs::     `memcached' Slabs Statistics
* ha-memcached-stats-items::     `memcached' Item Statistics
* ha-memcached-stats-sizes::     `memcached' Size Statistics

The `memcached' system has a built in statistics system that collects
information about the data being stored into the cache, cache hit
ratios, and detailed information on the memory usage and distribution
of information through the slab allocation used to store individual
items. Statistics are provided at both a basic level that provide the
core statistics, and more specific statistics for specific areas of the
`memcached' server.

This information can prove be very useful to ensure that you are
getting the correct level of cache and memory usage, and that your slab
allocation and configuration properties are set at an optimal level.

The stats interface is available through the standard `memcached'
protocol, so the reports can be accessed by using `telnet' to connect
to the `memcached'. Alternatively, most of the language API interfaces
provide a function for obtaining the statistics from the server.

For example, to get the basic stats using `telnet':

     shell> telnet localhost 11211
     Trying ::1...
     Connected to localhost.
     Escape character is '^]'.
     stats
     STAT pid 23599
     STAT uptime 675
     STAT time 1211439587
     STAT version 1.2.5
     STAT pointer_size 32
     STAT rusage_user 1.404992
     STAT rusage_system 4.694685
     STAT curr_items 32
     STAT total_items 56361
     STAT bytes 2642
     STAT curr_connections 53
     STAT total_connections 438
     STAT connection_structures 55
     STAT cmd_get 113482
     STAT cmd_set 80519
     STAT get_hits 78926
     STAT get_misses 34556
     STAT evictions 0
     STAT bytes_read 6379783
     STAT bytes_written 4860179
     STAT limit_maxbytes 67108864
     STAT threads 1
     END

When using Perl and the `Cache::Memcached' module, the `stats()'
function returns information about all the servers currently configured
in the connection object, and total statistics for all the `memcached'
servers as a whole.

For example, the Perl script below will obtain the stats and dump the
hash reference that is returned:

     use Cache::Memcached;
     use Data::Dumper;

     my $memc = new Cache::Memcached;
     $memc->set_servers(\@ARGV);

     print Dumper($memc->stats());

When executed on the same `memcached' as used in the `Telnet' example
above we get a hash reference with the host by host and total
statistics:

     $VAR1 = {
               'hosts' => {
                            'localhost:11211' => {
                                                   'misc' => {
                                                               'bytes' => '2421',
                                                               'curr_connections' => '3',
                                                               'connection_structures' => '56',
                                                               'pointer_size' => '32',
                                                               'time' => '1211440166',
                                                               'total_items' => '410956',
                                                               'cmd_set' => '588167',
                                                               'bytes_written' => '35715151',
                                                               'evictions' => '0',
                                                               'curr_items' => '31',
                                                               'pid' => '23599',
                                                               'limit_maxbytes' => '67108864',
                                                               'uptime' => '1254',
                                                               'rusage_user' => '9.857805',
                                                               'cmd_get' => '838451',
                                                               'rusage_system' => '34.096988',
                                                               'version' => '1.2.5',
                                                               'get_hits' => '581511',
                                                               'bytes_read' => '46665716',
                                                               'threads' => '1',
                                                               'total_connections' => '3104',
                                                               'get_misses' => '256940'
                                                             },
                                                   'sizes' => {
                                                                '128' => '16',
                                                                '64' => '15'
                                                              }
                                                 }
                          },
               'self' => {},
               'total' => {
                            'cmd_get' => 838451,
                            'bytes' => 2421,
                            'get_hits' => 581511,
                            'connection_structures' => 56,
                            'bytes_read' => 46665716,
                            'total_items' => 410956,
                            'total_connections' => 3104,
                            'cmd_set' => 588167,
                            'bytes_written' => 35715151,
                            'curr_items' => 31,
                            'get_misses' => 256940
                          }
             };

The statistics are divided up into a number of distinct sections, and
then can be requested by adding the type to the `stats' command. Each
statistics output is covered in more detail in the following sections.

   * General statistics, see *Note ha-memcached-stats-general::.

   * Slab statistics (`slabs'), see *Note ha-memcached-stats-slabs::.

   * Item statistics (`items'), see *Note ha-memcached-stats-items::.

   * Size statistics (`sizes'), see *Note ha-memcached-stats-sizes::.


File: manual.info,  Node: ha-memcached-stats-general,  Next: ha-memcached-stats-slabs,  Prev: ha-memcached-stats,  Up: ha-memcached-stats

16.4.1 `memcached' General Statistics
-------------------------------------

The output of the general statistics provides an overview of the
performance and use of the `memcached' instance. The statistics
returned by the command and their meaning is shown in the table below.

Statistic          Description
pid                Process id of the `memcached' instance.
uptime             Uptime (in seconds) for this `memcached' instance.
time               Current time (as epoch).
version            Version string of this instance.
pointer_size       Size of pointers for this host.
rusage_user        Total user time for this instance
                   (seconds:microseconds).
rusage_system      Total system time for this instance
                   (seconds:microseconds).
curr_items         Current number of items stored by this instance.
total_items        Total number of items stored during the life of this
                   instance.
bytes              Current number of bytes used by this server to store
                   items.
curr_connections   Current number of open connections.
total_connections  Total number of connections opened since the server
                   started running.
connection_structuresNumber of connection structures allocated by the
                   server.
cmd_get            Total number of retrieval requests (`get' operations).
cmd_set            Total number of storage requests (`set' operations).
get_hits           Number of keys that have been requested and found
                   present.
get_misses         Number of items that have been requested and not
                   found.
evictions          Number of valid items removed from cache to free
                   memory for new items.
bytes_read         Total number of bytes read by this server from
                   network.
bytes_written      Total number of bytes sent by this server to network.
limit_maxbytes     Number of bytes this server is allowed to use for
                   storage.
threads            Number of worker threads requested.

The most useful statistics from those given here are the number of
cache hits, misses, and evictions.

A large number of `get_misses' may just be an indication that the cache
is still being populated with information. The number should, over
time, decrease in comparison to the number of cache `get_hits'.  If,
however, you have a large number of cache misses compared to cache hits
after an extended period of execution, it may be an indication that the
size of the cache is too small and you either need to increase the
total memory size, or increase the number of the `memcached' instances
to improve the hit ratio.

A large number of `evictions' from the cache, particularly in
comparison to the number of items stored is a sign that your cache is
too small to hold the amount of information that you regularly want to
keep cached. Instead of items being retained in the cache, items are
being evicted to make way for new items keeping the turnover of items
in the cache high, reducing the efficiency of the cache.


File: manual.info,  Node: ha-memcached-stats-slabs,  Next: ha-memcached-stats-items,  Prev: ha-memcached-stats-general,  Up: ha-memcached-stats

16.4.2 `memcached' Slabs Statistics
-----------------------------------

To get the `slabs' statistics, use the `stats slabs' command, or the
API equivalent.

The slab statistics provide you with information about the slabs that
have created and allocated for storing information within the cache.
You get information both on each individual slab-class and total
statistics for the whole slab.

     STAT 1:chunk_size 104
     STAT 1:chunks_per_page 10082
     STAT 1:total_pages 1
     STAT 1:total_chunks 10082
     STAT 1:used_chunks 10081
     STAT 1:free_chunks 1
     STAT 1:free_chunks_end 10079
     STAT 9:chunk_size 696
     STAT 9:chunks_per_page 1506
     STAT 9:total_pages 63
     STAT 9:total_chunks 94878
     STAT 9:used_chunks 94878
     STAT 9:free_chunks 0
     STAT 9:free_chunks_end 0
     STAT active_slabs 2
     STAT total_malloced 67083616
     END

Individual stats for each slab class are prefixed with the slab ID. A
unique ID is given to each allocated slab from the smallest size up to
the largest. The prefix number indicates the slab class number in
relation to the calculated chunk from the specified growth factor.
Hence in the example, 1 is the first chunk size and 9 is the 9th chunk
allocated size.

The different parameters returned for each chunk size and the totals
are shown in the table below:

Statistic          Description
chunk_size         Space allocated to each chunk within this slab class.
chunks_per_page    Number of chunks within a single page for this slab
                   class.
total_pages        Number of pages allocated to this slab class.
total_chunks       Number of chunks allocated to the slab class.
used_chunks        Number of chunks allocated to an item..
free_chunks        Number of chunks not yet allocated to items.
free_chunks_end    Number of free chunks at the end of the last
                   allocated page.
active_slabs       Total number of slab classes allocated.
total_malloced     Total amount of memory allocated to slab pages.

The key values in the slab statistics are the `chunk_size', and the
corresponding `total_chunks' and `used_chunks' parameters. These given
an indication of the size usage of the chunks within the system.
Remember that one key/value pair will be placed into a chunk of a
suitable size.

From these stats you can get an idea of your size and chunk allocation
and distribution. If you are storing many items with a number of
largely different sizes, then you may want to adjust the chunk size
growth factor to increase in larger steps to prevent chunk and memory
wastage. A good indication of a bad growth factor is a high number of
different slab classes, but with relatively few chunks actually in use
within each slab.  Increasing the growth factor will create fewer slab
classes and therefore make better use of the allocated pages.


File: manual.info,  Node: ha-memcached-stats-items,  Next: ha-memcached-stats-sizes,  Prev: ha-memcached-stats-slabs,  Up: ha-memcached-stats

16.4.3 `memcached' Item Statistics
----------------------------------

To get the `items' statistics, use the `stats items' command, or the
API equivalent.

The `items' statistics give information about the individual items
allocated within a given slab class.

     STAT items:2:number 1
     STAT items:2:age 452
     STAT items:2:evicted 0
     STAT items:2:outofmemory 0
     STAT items:27:number 1
     STAT items:27:age 452
     STAT items:27:evicted 0
     STAT items:27:outofmemory 0

The prefix number against each statistics relates to the corresponding
chunk size, as returned by the `stats slabs' statistics. The result is
a display of the number of items stored within each chunk within each
slab size, and specific statistics about their age, eviction counts, and
out of memory counts. A summary of the statistics is given in the table
below.

Statistic          Description
number             The number of items currently stored in this slab
                   class.
age                The age of the oldest item within the slab class, in
                   seconds.
evicted            The number of items evicted to make way for new
                   entries.
outofmemory        The number of items for this slab class that have
                   triggered an out of memory error (only value when the
                   `-M' command line option is in effect).

Item level statistics can be used to determine how many items are
stored within a given slab and their freshness and recycle rate. You
can use this to help identify whether there are certain slab classes
that are triggering a much larger number of evictions that others.


File: manual.info,  Node: ha-memcached-stats-sizes,  Prev: ha-memcached-stats-items,  Up: ha-memcached-stats

16.4.4 `memcached' Size Statistics
----------------------------------

To get size statistics, use the `stats sizes' command, or the API
equivalent.

The size statistics provide information about the sizes and number of
items of each size within the cache. The information is returned as two
columns, the first column is the size of the item (rounded up to the
nearest 32 byte boundary), and the second column is the count of the
number of items of that size within the cache:

     96 35
     128 38
     160 807
     192 804
     224 410
     256 222
     288 83
     320 39
     352 53
     384 33
     416 64
     448 51
     480 30
     512 54
     544 39
     576 10065

*Caution*:

Running this statistic will lock up your cache as each item is read
from the cache and it's size calculated. On a large cache, this may
take some time and prevent any set or get operations until the process
completes.

The item size statistics are useful only to determine the sizes of the
objects you are storing. Since the actual memory allocation is relevant
only in terms of the chunk size and page size, the information will
only be useful during a careful debugging or diagnostic session.


File: manual.info,  Node: ha-memcached-faq,  Prev: ha-memcached-stats,  Up: ha-memcached

16.5 `memcached' FAQ
====================

*Questions*
   * 17.5.1: How does an event such as a crash of one of the
     `memcached' servers handled by the `memcached' client?

   * 17.5.2: Are there any, or are there any plans to introduce, a
     framework to hide the interaction of memcached from the
     application, i.e., within hibernate?

   * 17.5.3: What's a recommended hardware config for a memcached
     server?  Linux or Windows?

   * 17.5.4: How expensive is it to establish a memcache connection?
     Should those connections be pooled?

   * 17.5.5: How will the data will be handled when the `memcached'
     server is down?

   * 17.5.6: Can memcached be run on a Windows environment?

   * 17.5.7: What is the max size of an object you can store in
     memcache and is that configurable?

   * 17.5.8: What are best practices for testing an implementation, to
     ensure that it is an improvement over the MySQL query cache, and to
     measure the impact of `memcached' configuration changes? And would
     you recommend keeping the configuration very simple to start?

   * 17.5.9: Can MySQL actually trigger/store the changed data to
     memcached?

   * 17.5.10: So the responsibility lies with the application to
     populate and get records from the database as opposed to being a
     transparent cache layer for the db?

   * 17.5.11: `memcached' is fast - is there any overhead in not using
     persistent connections? If persistent is always recommended, what
     are the downsides (e.g. locking up?)

   * 17.5.12: Is compression available?

   * 17.5.13: File socket support for `memcached' from the localhost
     use to the local memcached server?

   * 17.5.14: What are the advantages of using UDFs when the get/sets
     are manageable from within the client code rather than the db?

   * 17.5.15: Is `memcached' typically a better solution for improving
     speed than MySQL Cluster and\or MySQL Proxy?

   * 17.5.16: What speed trade offs is there between `memcached' vs
     MySQL Query Cache? Where you check `memcached', and get data from
     MySQL and put it in `memcached' or just make a query and results
     are put into MySQL Query Cache.

   * 17.5.17: Does the `-L' flag automatically sense how much memory is
     being used by other memcached?

   * 17.5.18: Is the data inside of `memcached' secure?

   * 17.5.19: Can we implement different types of `memcached' as
     different nodes in the same server - so can there be deterministic
     and non deterministic in the same server?

   * 17.5.20: How easy is it to introduce `memcached' to an existing
     enterprise application instead of inclusion at project design?

   * 17.5.21: Can `memcached' work with `ASPX'?

   * 17.5.22: If I have an object larger then a MB, do I have to
     manually split it or can I configure `memcached' to handle larger
     objects?

   * 17.5.23: Is it true `memcached' will be much more effective with
     db-read-intensive applications than with db-write-intensive
     applications?

   * 17.5.24: How does `memcached' compare to nCache?

   * 17.5.25: Doing a direct telnet to the memcached port, is that just
     for that one machine, or does it magically apply across all nodes?

   * 17.5.26: Is memcached more effective for video and audio as
     opposed to textual read/writes

   * 17.5.27: We are caching XML by serialising using saveXML(),
     because PHP cannot serialise DOM objects; Some of the XML is
     variable and is modified per-request. Do you recommend caching
     then using XPath, or is it better to rebuild the DOM from separate
     node-groups?

   * 17.5.28: Do the memcache UDFs work under 5.1?

   * 17.5.29: How are auto-increment columns in the MySQL database
     coordinated across multiple instances of memcached?

   * 17.5.30: If you log a complex class (with methods that do
     calculation etc) will the get from Memcache re-create the class on
     the way out?

*Questions and Answers* *17.5.1: ** How does an event such as a crash
of one of the `memcached' servers handled by the `memcached' client?  *

There is no automatic handling of this. If your client fails to get a
response from a server then it should fall back to loading the data
from the MySQL database.

The client APIs all provide the ability to add and remove `memcached'
instances on the fly. If within your application you notice that
`memcached' server is no longer responding, your can remove the server
from the list of servers, and keys will automatically be redistributed
to another `memcached' server in the list. If retaining the cache
content on all your servers is important, make sure you use an API that
supports a consistent hashing algorithm. For more information, see
*Note ha-memcached-using-hashtypes::.

*17.5.2: ** Are there any, or are there any plans to introduce, a
framework to hide the interaction of memcached from the application,
i.e., within hibernate?  *

There are lots of projects working with `memcached'. There is a Google
Code implementation of Hibernate and `memcached' working together. See
`http://code.google.com/p/hibernate-memcached/'.

*17.5.3: ** What's a recommended hardware config for a memcached server?
Linux or Windows?  *

`memcached' is only available on Unix/Linux, so using a Windows machine
is not an option. Outside of this, `memcached' has a very low
processing overhead.  All that is required is spare physical RAM
capacity. The point is not that you should necessarily deploy a
dedicated `memcached' server. If you have web, application, or database
servers that have spare RAM capacity, then use them with `memcached'.

If you want to build and deploy a dedicated `memcached' servers, then
you use a relatively low-power CPU, lots of RAM and one or more Gigabit
Ethernet interfaces.

*17.5.4: ** How expensive is it to establish a memcache connection?
Should those connections be pooled?  *

Opening the connection is relatively inexpensive, because there is no
security, authentication or other handshake taking place before you can
start sending requests and getting results. Most APIs support a
persistent connection to a `memcached' instance to reduce the latency.
Connection pooling would depend on the API you are using, but if you
are communicating directly over TCP/IP, then connection pooling would
provide some small performance benefit.

*17.5.5: ** How will the data will be handled when the `memcached'
server is down?  *

The behavior is entirely application dependent. Most applications will
fall back to loading the data from the database (just as if they were
updating the `memcached') information. If you are using multiple
`memcached' servers, you may also want to remove a server from the list
to prevent the missing server affecting performance. This is because
the client will still attempt to communicate the `memcached' that
corresponds to the key you are trying to load.

*17.5.6: ** Can memcached be run on a Windows environment?  *

No. Currently `memcached' is available only on the Unix/Linux platform.
There is an unofficial port available, see
`http://www.codeplex.com/memcachedproviders'.

*17.5.7: ** What is the max size of an object you can store in memcache
and is that configurable?  *

The default maximum object size is 1MB. If you want to increase this
size, you have to re-compile `memcached'.  You can modify the value of
the `POWER_BLOCK' within the `slabs.c' file within the source.

*17.5.8: ** What are best practices for testing an implementation, to
ensure that it is an improvement over the MySQL query cache, and to
measure the impact of `memcached' configuration changes? And would you
recommend keeping the configuration very simple to start?  *

The best way to test the performance is to start up a `memcached'
instance. First, modify your application so that it stores the data
just before the data is about to be used or displayed into
`memcached'.Since the APIs handle the serialization of the data, it
should just be a one line modification to your code. Then, modify the
start of the process that would normally load that information from
MySQL with the code that requests the data from `memcached'.  If the
data cannot be loaded from `memcached', default to the MySQL process.

All of the changes required will probably amount to just a few lines of
code. To get the best benefit, make sure you cache entire objects (for
example, all the components of a web page, blog post, discussion
thread, etc.), rather than using `memcached' as a simple cache of
individuals rows of MySQL tables. You should see performance benefits
almost immediately.

Keeping the configuration very simple at the start, or even over the
long term, is very easy with `memcached'.  Once you have the basic
structure up and running, the only addition you may want to make is to
add more servers into the list of servers used by your clients. You
don't need to manage the `memcached' servers, and there is no complex
configuration, just add more servers to the list and let the client API
and the `memcached' servers make the decisions.

*17.5.9: ** Can MySQL actually trigger/store the changed data to
memcached?  *

Yes. You can use the MySQL UDFs for `memcached' and either write
statements that directly set the values in the `memcached' server, or
use triggers or stored procedures to do it for you. For more
information, see *Note ha-memcached-interfaces-mysqludf::

*17.5.10: ** So the responsibility lies with the application to
populate and get records from the database as opposed to being a
transparent cache layer for the db?  *

Yes. You load the data from the database and write it into the cache
provided by `memcached'. Using `memcached' as a simple database row
cache, however, is probably inefficient. The best way to use
`memcached' is to load all of the information from the database
relating to a particular object, and then cache the entire object. For
example, in a blogging environment, you might load the blog, associated
comments, categories and so on, and then cache all of the information
relating to that blog post. The reading of the data from the database
will require multiple SQL statements and probably multiple rows of data
to complete, which is time consuming. Loading the entire blog post and
the associated information from `memcached' is just one operation and
doesn't involve using the disk or parsing the SQL statement.

*17.5.11: ** `memcached' is fast - is there any overhead in not using
persistent connections? If persistent is always recommended, what are
the downsides (e.g. locking up?)  *

If you don't use persistent connections when communicating with
`memcached' then there will be a small increase in the latency of
opening the connection each time. The effect is comparable to use
non-persistent connections with MySQL.

In general, the chance of locking or other issues with persistent
connections is minimal, because there is very little locking within
`memcached'. If there is a problem then eventually your request will
timeout and return no result so your application will need to load from
MySQL again.

*17.5.12: ** Is compression available?  *

Yes. Most of the client APIs support some sort of compression, and some
even allow you to specify the threshold at which a value is deemed
appropriate for compression during storage.

*17.5.13: ** File socket support for `memcached' from the localhost use
to the local memcached server?  *

You can use the `-s' option to `memcached' to specify the location of a
file socket. This automatically disables network support.

*17.5.14: ** What are the advantages of using UDFs when the get/sets are
manageable from within the client code rather than the db?  *

Sometimes you want to be able to be able to update the information
within `memcached' based on a generic database activity, rather than
relying on your client code. For example, you may want to update status
or counter information in `memcached' through the use of a trigger or
stored procedure. For some situations and applications the existing use
of a stored procedure for some operations means that updating the value
in `memcached' from the database is easier than separately loading and
communicating that data to the client just so the client can talk to
`memcached.'

In other situations, when you are using a number of different clients
and different APIs, you don't want to have to write (and maintain) the
code required to update `memcached' in all the environments. Instead,
you do this from within the database and the client never gets involved.

*17.5.15: ** Is `memcached' typically a better solution for improving
speed than MySQL Cluster and\or MySQL Proxy?  *

Both MySQL Cluster and MySQL Proxy still require access to the
underlying database to retrieve the information. This implies both a
parsing overhead for the statement and, often, disk based access to
retrieve the data you have selected.

The advantage of `memcached' is that you can store entire objects or
groups of information that may require multiple SQL statements to
obtain. Restoring the result of 20 SQL statements formatted into a
structure that your application can use directly without requiring any
additional processing is always going to be faster than building that
structure by loading the rows from a database.

*17.5.16: ** What speed trade offs is there between `memcached' vs
MySQL Query Cache? Where you check `memcached', and get data from MySQL
and put it in `memcached' or just make a query and results are put into
MySQL Query Cache.  *

In general, the time difference between getting data from the MySQL
Query Cache and getting the exact same data from `memcached' is very
small.

However, the benefit of `memcached' is that you can store any
information, including the formatted and processed results of many
queries into a single `memcached' key. Even if all the queries that you
executed could be retrieved from the Query Cache without having to go
to disk, you would still be running multiple queries (with network and
other overhead) compared to just one for the `memcached' equivalent. If
your application uses objects, or does any kind of processing on the
information, with `memcached' you can store the post-processed version,
so the data you load is immediately available to be used. With data
loaded from the Query Cache, you would still have to do that processing.

In addition to these considerations, keep in mind that keeping data in
the MySQL Query Cache is difficult as you have no control over the
queries that are stored. This means that a slightly unusual query can
temporarily clear a frequently used (and normally cached) query,
reducing the effectiveness of your Query Cache. With `memcached' you
can specify which objects are stored, when they are stored, and when
they should be deleted giving you much more control over the
information stored in the cache.

*17.5.17: ** Does the `-L' flag automatically sense how much memory is
being used by other memcached?  *

No. There is no communication or sharing of information between
`memcached' instances.

*17.5.18: ** Is the data inside of `memcached' secure?  *

No, there is no security required to access or update the information
within a `memcached' instance, which means that anybody with access to
the machine has the ability to read, view and potentially update the
information. If you want to keep the data secure, you can encrypt and
decrypt the information before storing it. If you want to restrict the
users capable of connecting to the server, your only choice is to
either disable network access, or use IPTables or similar to restrict
access to the `memcached' ports to a select set of hosts.

*17.5.19: ** Can we implement different types of `memcached' as
different nodes in the same server - so can there be deterministic and
non deterministic in the same server?  *

Yes. You can run multiple instances of `memcached' on a single server,
and in your client configuration you choose the list of servers you
want to use.

*17.5.20: ** How easy is it to introduce `memcached' to an existing
enterprise application instead of inclusion at project design?  *

In general, it is very easy. In many languages and environments the
changes to the application will be just a few lines, first to attempt
to read from the cache when loading data and then fall back to the old
method, and to update the cache with information once the data has been
read.

`memcached' is designed to be deployed very easily, and you shouldn't
require significant architectural changes to your application to use
`memcached'.

*17.5.21: ** Can `memcached' work with `ASPX'?  *

There are ports and interfaces for many languages and environments.
ASPX relies on an underlying language such as C# or VisualBasic, and if
you are using ASP.NET then there is a C# `memcached' library. For more
information, see . (https://sourceforge.net/projects/memcacheddotnet/)

*17.5.22: ** If I have an object larger then a MB, do I have to manually
split it or can I configure `memcached' to handle larger objects?  *

You would have to manually split it.  `memcached' is very simple, you
give it a key and some data, it tries to cache it in RAM. If you try to
store more than the default maximum size, the value is just truncated
for speed reasons.

*17.5.23: ** Is it true `memcached' will be much more effective with
db-read-intensive applications than with db-write-intensive
applications?  *

Yes. `memcached' plays no role whatsoever in database writes, it is a
method of caching data already read from the database in RAM.

*17.5.24: ** How does `memcached' compare to nCache?  *

The main benefit of `memcached' is that is very easy to deploy and
works with a wide range of languages and environments, including .NET,
Java, Perl, Python, PHP, even MySQL. `memcached' is also very
lightweight in terms of systems and requirements, and you can easily
add as many or as few `memcached' servers as you need without changing
the individual configuration.  `memcached' does require additional
modifications to the application to take advantage of functionality
such as multiple `memcached' servers.

*17.5.25: ** Doing a direct telnet to the memcached port, is that just
for that one machine, or does it magically apply across all nodes?  *

Just one. There is no communication between different instances of
`memcached', even if each instance is running on the same machine.

*17.5.26: ** Is memcached more effective for video and audio as opposed
to textual read/writes *

`memcached' doesn't care what information you are storing. To
`memcached', any value you store is just a stream of data. Remember,
though, that the maximum size of an object you can store in `memcached'
without modifying the source code is 1MB, so it's usability with audio
and video content is probably significantly reduced. Also remember that
`memcached' is a solution for caching information for reading. It
shouldn't be used for writes, except when updating the information in
the cache.

*17.5.27: ** We are caching XML by serialising using saveXML(), because
PHP cannot serialise DOM objects; Some of the XML is variable and is
modified per-request. Do you recommend caching then using XPath, or is
it better to rebuild the DOM from separate node-groups?  *

You would need to test your application using the different methods to
determine this information. You may find that the default serialization
within PHP may allow you to store DOM objects directly into the cache.

*17.5.28: ** Do the memcache UDFs work under 5.1?  *

Yes.

*17.5.29: ** How are auto-increment columns in the MySQL database
coordinated across multiple instances of memcached?  *

They aren't. There is no relationship between MySQL and `memcached'
unless your application (or, if you are using the MySQL UDFs for
`memcached', your database definition) creates one.

If you are storing information based on an auto-increment key into
multiple instances of `memcached' then the information will only be
stored on one of the `memcached' instances anyway. The client uses the
key value to determine which `memcached' instance to store the
information, it doesn't store the same information across all the
instances, as that would be a waste of cache memory.

*17.5.30: ** If you log a complex class (with methods that do
calculation etc) will the get from Memcache re-create the class on the
way out?  *

In general, yes. If the serialization method within the API/language
that you are using supports it, then methods and other information will
be stored and retrieved.


File: manual.info,  Node: mysql-proxy,  Next: load-balancer,  Prev: ha-memcached,  Up: Top

17 MySQL Proxy
**************

* Menu:

* mysql-proxy-platforms::        MySQL Proxy Supported Platforms
* mysql-proxy-install::          Installing MySQL Proxy
* mysql-proxy-cmdline::          MySQL Proxy Command-Line Options
* mysql-proxy-scripting::        MySQL Proxy Scripting
* mysql-proxy-using::            Using MySQL Proxy
* mysql-proxy-faq::              MySQL Proxy FAQ

The MySQL Proxy is an application that communicates over the network
using the MySQL Network Protocol and provides communication between one
or more MySQL servers and one or more MySQL clients. In the most basic
configuration, MySQL Proxy simply passes on queries from the client to
the MySQL Server and returns the responses from the MySQL Server to the
client.

Because MySQL Proxy uses the MySQL network protocol, any MySQL
compatible client (include the command line client, any clients using
the MySQL client libraries, and any connector that supports the MySQL
network protocol) can connect to the proxy without modification.

In addition to the basic pass-through configuration, the MySQL Proxy is
also capable of monitoring and altering the communication between the
client and the server. This interception of the queries enables you to
add profiling, and the interception of the exchanges is scriptable
using the Lua scripting language.

By intercepting the queries from the client, the proxy can insert
additional queries into the list of queries sent to the server, and
remove the additional results when they are returned by the server.
Using this functionality you can add informational statements to each
query, for example to monitor their execution time or progress, and
separately log the results, while still returning the results from the
original query to the client.

The proxy allows you to perform additional monitoring, filtering or
manipulation on queries without you having to make any modifications to
the client and without the client even being aware that it is
communicating with anything but a genuine MySQL server.

*Warning*:

MySQL Proxy is currently an Alpha release and should not be used within
production environments.

*Important*:

MySQL Proxy is compatible with MySQL 5.0.x or later. Testing has not
been performed with Version 4.1. Please provide feedback on your
experiences via the MySQL Proxy Forum
(http://forums.mysql.com/list.php?146).


File: manual.info,  Node: mysql-proxy-platforms,  Next: mysql-proxy-install,  Prev: mysql-proxy,  Up: mysql-proxy

17.1 MySQL Proxy Supported Platforms
====================================

MySQL Proxy is currently available as a pre-compiled binary for the
following platforms:

   * Linux (including RedHat, Fedora, Debian, SuSE) and derivatives.

   * Mac OS X

   * FreeBSD

   * IBM AIX

   * Sun Solaris

Other Unix/Linux platforms not listed should be compatible by using the
source package and building MySQL Proxy locally.

System requirements for the MySQL Proxy application are the same as the
main MySQL server. Currently MySQL Proxy is compatible only with MySQL
5.0.1 and later. MySQL Proxy is provided as a standalone, statically
linked binary. You do not need to have MySQL or Lua installed.


File: manual.info,  Node: mysql-proxy-install,  Next: mysql-proxy-cmdline,  Prev: mysql-proxy-platforms,  Up: mysql-proxy

17.2 Installing MySQL Proxy
===========================

* Menu:

* mysql-proxy-install-binary::   Installing MySQL Proxy from a binary distribution
* mysql-proxy-install-source::   Installing MySQL Proxy from a source distribution
* mysql-proxy-install-svn::      Installing MySQL Proxy from the Subversion repository

You have three choices for installing MySQL Proxy:

   * Pre-compiled binaries are available for a number of different
     platforms. See *Note mysql-proxy-install-binary::.

   * You can install from the source code if you want to build on an
     environment not supported by the binary distributions. See *Note
     mysql-proxy-install-source::.

   * The latest version of the MySQL proxy source code is available
     through a development repository is the best way to stay up to
     date with the latest fixes and revisions. See *Note
     mysql-proxy-install-svn::.


File: manual.info,  Node: mysql-proxy-install-binary,  Next: mysql-proxy-install-source,  Prev: mysql-proxy-install,  Up: mysql-proxy-install

17.2.1 Installing MySQL Proxy from a binary distribution
--------------------------------------------------------

If you download the binary packages then you need only to extract the
package and then copy the `mysql-proxy' file to your desired location.
For example:

     $ tar zxf MYSQL-PROXY-0.5.0.TAR.GZ
     $ cp ./mysql-proxy-0.5.0/sbin/mysql-proxy /usr/local/sbin


File: manual.info,  Node: mysql-proxy-install-source,  Next: mysql-proxy-install-svn,  Prev: mysql-proxy-install-binary,  Up: mysql-proxy-install

17.2.2 Installing MySQL Proxy from a source distribution
--------------------------------------------------------

If you have downloaded the source package then you will need to compile
the MySQL Proxy before using it. To build you will need to have the
following installed:

   * libevent 1.x or higher (1.3b or later is preferred)

   * lua 5.1.x or higher

   * glib2 2.6.0 or higher

   * pkg-config

   * MySQL 5.0.x or higher developer files

*Note*:

On some operating systems you may need to manually build the required
components to get the latest version. If you are having trouble
compiling MySQL Proxy then consider using one of the binary
distributions.

Once these components are installed, you need to configure and then
build:

     $ tar zxf MYSQL-PROXY-0.5.0.TAR.GZ
     $ cd mysql-proxy-0.5.0
     $ ./configure
     $ make

If you want to test the build, then use the `check' target to `make':

     $ make check

The tests try to connect to `localhost' using the `root' user. If you
need to provide a password, set the `MYSQL_PASSWORD' environment
variable:

     $ MYSQL_PASSWORD=root_pwd make check

You can install using the `install' target:

     $ make install

By default `mysql-proxy' is installed into
`/usr/local/sbin/mysql-proxy'. The Lua example scripts are copied into
`/usr/local/share'.


File: manual.info,  Node: mysql-proxy-install-svn,  Prev: mysql-proxy-install-source,  Up: mysql-proxy-install

17.2.3 Installing MySQL Proxy from the Subversion repository
------------------------------------------------------------

The MySQL Proxy source is available through a public Subversion
repository and is the quickest way to get hold of the latest releases
and fixes.

To build from the Subversion repository, you need the following
components already installed:

   * Subversion 1.3.0 or higher

   * `libtool' 1.5 or higher

   * `autoconf' 2.56 or higher

   * `automake' 1.9 or higher

   * `libevent' 1.x or higher (1.3b or later is preferred)

   * `lua' 5.1.x or higher

   * `glib2' 2.4.0 or higher

   * `pkg-config'

   * `MySQL' 5.0.x or higher developer files

To checkout a local copy of the Subversion repository, use `svn':

     $ svn co http://svn.MySQL.com/svnpublic/mysql-proxy/ mysql-proxy

The above command will download a complete version of the Subversion
repository for `mysql-proxy'. The main source files are located within
the `trunk' subdirectory. The configuration scripts need to be
generated before you can configure and build `mysql-proxy'. The
`autogen.sh' script will generate the configuration scripts for you:

     $ sh ./autogen.sh

The script creates the standard `configure' script, which you can then
use to configure and build with `make':

     $ ./configure
     $ make
     $ make install

If you want to create a standalone source distribution, identical to
the source distribution available for download:

     $ make distcheck

The above will create the file `mysql-proxy-0.5.0.tar.gz' within the
current directory.


File: manual.info,  Node: mysql-proxy-cmdline,  Next: mysql-proxy-scripting,  Prev: mysql-proxy-install,  Up: mysql-proxy

17.3 MySQL Proxy Command-Line Options
=====================================

To start `mysql-proxy' you can just run the command directly. However,
for most situations you will want to specify at the very least the
address/hostname and port number of the backend MySQL server to which
the MySQL Proxy should pass on queries.

You can get a list of the supported command-line options using the
`--help-all' command-line option. The majority of these options set up
the environment, either in terms of the address/port number that
`mysql-proxy' should listen on for connections, or the onward
connection to a MySQL server. A full description of the options is
shown below:

   * `--help-all' -- show all help options.

   * `--help-admin ' -- show options for the admin-module.

   * `--help-proxy' -- Show options for the proxy-module.

   * `--admin-address=host:port' -- specify the hostname (or IP
     address) and port for the administration port. The default is
     `localhost:4041'.

   * `--proxy-address=host:port' -- the listening hostname (or IP
     address) and port of the proxy server. The default is
     `localhost:4040'.

   * `--proxy-read-only-backend-address=host:port' -- the listening
     hostname (or IP address) and port of the proxy server for
     read-only connections. The default is for this information not to
     be set.

   * `--proxy-backend-addresses=host:port' -- the hostname (or IP
     address) and port of the MySQL server to connect to. You can
     specify multiple backend servers by supplying multiple options.
     Clients are connected to each backend server in round-robin
     fashion. For example, if you specify two servers A and B, the
     first client connection will go to server A; the second client
     connection to server B and the third client connection to server A.

   * `--proxy-skip-profiling ' -- disables profiling of queries
     (tracking time statistics). The default is for tracking to be
     enabled.

   * `--proxy-fix-bug-25371 ' -- gets round an issue when connecting to
     a MySQL server later than 5.1.12 when using a MySQL client library
     of any earlier version.

   * `--proxy-lua-script=file ' -- specify the Lua script file to be
     loaded. Note that the script file is not physically loaded and
     parsed until a connection is made.  Also note that the specified
     Lua script is reloaded for each connection; if the content of the
     Lua script changes while `mysql-proxy' is running then the updated
     content will automatically be used when a new connection is made.

   * `--daemon' -- starts the proxy in daemon mode.

   * `--pid-file=file' -- sets the name of the file to be used to store
     the process ID.

   * `--version' -- show the version number.

The most common usage is as a simple proxy service (i.e. without
addition scripting). For basic proxy operation you must specify at
least one `proxy-backend-addresses' option to specify the MySQL server
to connect to by default:

     $ mysql-proxy
     --proxy-backend-addresses=MySQL.example.com:3306

The default proxy port is `4040', so you can connect to your MySQL
server through the proxy by specifying the hostname and port details:

     $ mysql --host=localhost --port=4040

If your server requires authentication information then this will be
passed through natively without alteration by `mysql-proxy', so you
must also specify the authentication information if required:

     $ mysql --host=localhost --port=4040 \
        --user=username --password=password

You can also connect to a read-only port (which filters out `UPDATE'
and `INSERT' queries) by connecting to the read-only port. By default
the hostname is the default, and the port is `4042', but you can alter
the host/port information by using the `--proxy-read-only-address'
command-line option.

For more detailed information on how to use these command line options,
and `mysql-proxy' in general in combination with Lua scripts, see *Note
mysql-proxy-using::.


File: manual.info,  Node: mysql-proxy-scripting,  Next: mysql-proxy-using,  Prev: mysql-proxy-cmdline,  Up: mysql-proxy

17.4 MySQL Proxy Scripting
==========================

* Menu:

* mysql-proxy-scripting-injection::  Proxy Scripting Sequence During Query Injection
* mysql-proxy-scripting-structures::  Internal Structures
* mysql-proxy-scripting-connect-server::  Capturing a connection with `connect_server()'
* mysql-proxy-scripting-read-handshake::  Examining the handshake with `read_handshake()'
* mysql-proxy-scripting-read-auth::  Examining the authentication credentials with `read_auth()'
* mysql-proxy-scripting-read-auth-result::  Accessing authentication information with `read_auth_result()'
* mysql-proxy-scripting-read-query::  Manipulating Queries with `read_query()'
* mysql-proxy-scripting-read-query-result::  Manipulating Results with `read_query_result()'

You can control how MySQL Proxy manipulates and works with the queries
and results that are passed on to the MySQL server through the use of
the embedded Lua scripting language. You can find out more about the
Lua programming language from the Lua Website (http://www.lua.org).

The primary interaction between MySQL Proxy and the server is provided
by defining one or more functions through an Lua script.  A number of
functions are supported, according to different events and operations
in the communication sequence between a client and one or more backend
MySQL servers:

   * `connect_server()' -- this function is called each time a
     connection is made to MySQL Proxy from a client. You can use this
     function during load-balancing to intercept the original
     connection and decide which server the client should ultimately be
     attached to. If you don't define a special solution, then a simple
     round-robin style distribution is used by default.

   * `read_handshake()' -- this function is called when the initial
     handshake information is returned by the server. You can capture
     the handshake information returned and provide additional checks
     before the authorization exchange takes place.

   * `read_auth()' -- this function is called when the authorization
     packet (username, password, default database) are submitted by the
     client to the server for authentication.

   * `read_auth_result()' -- this function is called when the server
     returns an authorization packet to the client indicating whether
     the authorization succeeded.

   * `read_query()' -- this function is called each time a query is
     sent by the client to the server.  You can use this to edit and
     manipulate the original query, including adding new queries before
     and after the original statement. You can also use this function
     to return information directly to the client, bypassing the server,
     which can be useful to filter unwanted queries or queries that
     exceed known limits.

   * `read_query_result()' -- this function is called each time a
     result is returned from the server, providing you have manually
     injected queries into the query queue. If you have not explicitly
     inject queries within the `read_query()' function then this
     function is not triggered. You can use this to edit the result
     set, or to remove or filter the result sets generated from
     additional queries you injected into the queue when using
     `read_query()'.

The table below describes the direction of flow of information at the
point when the function is triggered.

Function               Supplied Information   Direction
`connect_server()'     None                   Client to Server
`read_handshake()'     Handshake packet       Server to Client
`read_auth()'          Authorization packet   Client to Server
`read_auth_result()'   Authorization response Server to Client
`read_query()'         Query                  Client to Server
`read_query_result()'  Query result           Server to Client

By default, all functions return a result that indicates that the data
should be passed on to the client or server (depending on the direction
of the information being transferred). This return value can be
overridden by explicitly returning a constant indicating that a
particular response should be sent. For example, it is possible to
construct result set information by hand within `read_query()' and to
return the resultset directly to the client without ever sending the
original query to the server.

In addition to these functions, a number of built-in structures provide
control over how MySQL Proxy forwards on queries and returns the
results by providing a simplified interface to elements such as the
list of queries and the groups of result sets that are returned.


File: manual.info,  Node: mysql-proxy-scripting-injection,  Next: mysql-proxy-scripting-structures,  Prev: mysql-proxy-scripting,  Up: mysql-proxy-scripting

17.4.1 Proxy Scripting Sequence During Query Injection
------------------------------------------------------

The figure below gives an example of how the proxy might be used when
injecting queries into the query queue. Because the proxy sits between
the client and MySQL server, what the proxy sends to the server, and
the information that the proxy ultimately returns to the client do not
have to match or correlate. Once the client has connected to the proxy,
the following sequence occurs for each individual query sent by the
client.

MySQL Proxy architecture

  1. The client submits one query to the proxy, the `read_query()'
     function within the proxy is triggered. The function adds the
     query to the query queue.

  2. Once manipulation by `read_query()' has completed, the queries are
     submitted, sequentially, to the MySQL server.

  3. The MySQL server returns the results from each query, one result
     set for each query submitted. The `read_query_result()' function is
     triggered for each result set, and each invocation can decide
     which result set to return to the client

For example, you can queue additional queries into the global query
queue to be processed by the server. This can be used to add
statistical information by adding queries before and after the original
query, changing the original query:

     SELECT * FROM City;

Into a sequence of queries:

     SELECT NOW();
     SELECT * FROM City;
     SELECT NOW();

You can also modify the original statement, for example to add
`EXPLAIN' to each statement executed to get information on how the
statement was processed, again altering our original SQL statement into
a number of statements:

     SELECT * FROM City;
     EXPLAIN SELECT * FROM City;

In both of these examples, the client would have received more result
sets than expected. Regardless of how you manipulate the incoming query
and the returned result, the number of queries returned by the proxy
must match the number of original queries sent by the client.

You could adjust the client to handle the multiple result sets sent by
the proxy, but in most cases you will want the existence of the proxy
to remain transparent. To ensure that the number of queries and result
sets match, you can use the MySQL Proxy `read_query_result()' to
extract the additional result set information and return only the
result set the client originally requested back to the client. You can
achieve this by giving each query that you add to the query queue a
unique ID, and then filter out queries that do not match the original
query ID when processing them with `read_query_result()'.


File: manual.info,  Node: mysql-proxy-scripting-structures,  Next: mysql-proxy-scripting-connect-server,  Prev: mysql-proxy-scripting-injection,  Up: mysql-proxy-scripting

17.4.2 Internal Structures
--------------------------

There are a number of internal structures within the scripting element
of MySQL Proxy. The primary structure is `proxy' and this provides an
interface to the many common structures used throughout the script,
such as connection lists and configured backend servers. Other
structures, such as the incoming packet from the client and result sets
are only available within the context of one of the scriptable
functions.

Attribute              Description
`connection'           A structure containing the active client
                       connections. For a list of attributes, see
                       
                       `proxy.connection' .
`servers'              A structure containing the list of configured
                       backend servers. For a list of attributes, see
                       
                       `proxy.backends' .
`queries'              A structure containing the queue of queries that
                       will be sent to the server during a single client
                       query. For a list of attributes, see
                       
                       `proxy.queries' .
`PROXY_VERSION'        The version number of MySQL Proxy, encoded in
                       hex. You can use this to check that the version
                       number supports a particular option from within
                       the Lua script. Note that the value is encoded as
                       a hex value, so to check the version is at least
                       0.5.1 you compare against `0x00501'.

* `proxy.connection' *

The `proxy.connection' object is read only, and provides information
about the current connection.

Attribute              Description
`thread_id'            The thread ID of the connection.
`backend_ndx'          The ID of the server used for this connection.
                       This is an ID valid against the list of
                       configured servers available through the
                       `proxy.backends' object.

* `proxy.backends' *

The `proxy.backends' table is partially writable and contains an array
of all the configured backend servers and the server metadata (IP
address, status, etc.). You can determine the array index of the
current connection using `proxy.connection["backend_ndx"]' which is the
index into this table of the backend server being used by the active
connection.

The attributes for each entry within the `proxy.backends' table are
shown in this table.

Attribute              Description
`address'              The hostname/port combination used for this
                       connection
`connected_clients'    The number of clients currently connected.
`state'                The status of the backend server. See *Note
                       mysql-proxy-scripting-structures-backend-states::.

* `proxy.queries' *

The `proxy.queries' object is a queue representing the list of queries
to be sent to the server. The queue is not populated automatically, but
if you do not explicitly populate the queue then queries are passed on
to the backend server verbatim. Also, if you do not populate the query
queue by hand, then the `read_query_result()' function is not triggered.

The following methods are supported for populating the `proxy.queries'
object.

Function               Description
`append(id,packet)'    Appends a query to the end of the query queue.
                       The `id' is an integer identifier that you can
                       use to recognize the query results when they are
                       returned by the server.  The packet should be a
                       properly formatted query packet.
`prepend(id,packet)'   Prepends a query to the query queue. The `id' is
                       an identifier that you can use to recognize the
                       query results when they are returned by the
                       server. The packet should be a properly formatted
                       query packet.
`reset()'              Empties the query queue.
`len()'                Returns the number of query packets in the queue.

For example, you could append a query packet to the `proxy.queries'
queue by using the `append()':

     proxy.queries:append(1,packet)

*`proxy.response'*

The `proxy.response' structure is used when you want to return your own
MySQL response, instead of forwarding a packet that you have received a
backend server. The structure holds the response type information, an
optional error message, and the result set (rows/columns) that you want
to return.

Attribute              Description
`type'                 The type of the response. The type must be either
                       `MYSQLD_PACKET_OK' or `MYSQLD_PACKET_ERR'. If the
                       `MYSQLD_PACKET_ERR', then you should set the
                       value of the `mysql.response.errmsg' with a
                       suitable error message.
`errmsg'               A string containing the error message that will
                       be returned to the client.
`resultset'            A structure containing the result set information
                       (columns and rows), identical to what would be
                       returned when returning a results from a `SELECT'
                       query.

When using `proxy.response' you either set `proxy.response.type' to
`proxy.MYSQLD_PACKET_OK' and then build `resultset' to contain the
results that you want to return, or set `proxy.response.type' to
`proxy.MYSQLD_PACKET_ERR' and set the `proxy.response.errmsg' to a
string with the error message. To send the completed resultset or error
message, you should return the `proxy.PROXY_SEND_RESULT' to trigger the
return of the packet information.

An example of this can be seen in the `tutorial-resultset.lua' script
within the MySQL Proxy package:

     if string.lower(command) == "show" and string.lower(option) == "querycounter" then
             ---
             -- proxy.PROXY_SEND_RESULT requires
             --
             -- proxy.response.type to be either
             -- * proxy.MYSQLD_PACKET_OK or
             -- * proxy.MYSQLD_PACKET_ERR
             --
             -- for proxy.MYSQLD_PACKET_OK you need a resultset
             -- * fields
             -- * rows
             --
             -- for proxy.MYSQLD_PACKET_ERR
             -- * errmsg
             proxy.response.type = proxy.MYSQLD_PACKET_OK
             proxy.response.resultset = {
                     fields = {
                             { type = proxy.MYSQL_TYPE_LONG, name = "global_query_counter", },
                             { type = proxy.MYSQL_TYPE_LONG, name = "query_counter", },
                     },
                     rows = {
                             { proxy.global.query_counter, query_counter }
                     }
             }

             -- we have our result, send it back
             return proxy.PROXY_SEND_RESULT
     elseif string.lower(command) == "show" and string.lower(option) == "myerror" then
             proxy.response.type = proxy.MYSQLD_PACKET_ERR
             proxy.response.errmsg = "my first error"

             return proxy.PROXY_SEND_RESULT

*`proxy.response.resultset'*

The `proxy.response.resultset' structure should be populated with the
rows and columns of data that you want to return. The structure
contains the information about the entire result set, with the
individual elements of the data shown in the table below.

Attribute              Description
`fields'               The definition of the columns being returned.
                       This should be a dictionary structure with the
                       `type' specifying the MySQL data type, and the
                       `name' specifying the column name.  Columns
                       should be listed in the the order of the column
                       data that will be returned.
`flags'                A number of flags related to the resultset. Valid
                       flags include `auto_commit' (whether an automatic
                       commit was triggered), `no_good_index_used' (the
                       query executed without using an appropriate
                       index), and `no_index_used' (the query executed
                       without using any index).
`rows'                 The actual row data. The information should be
                       returned as an array of arrays. Each inner array
                       should contain the column data, with the outer
                       array making up the entire result set.
`warning_count'        The number of warnings for this result set.
`affected_rows'        The number of rows affected by the original
                       statement.
`insert_id'            The last insert ID for an auto-incremented column
                       in a table.
`query_status'         The status of the query operation. You can use the
                       `MYSQLD_PACKET_OK' or `MYSQLD_PACKET_ERR'
                       constants to populate this parameter.

For an example of the population of this table, see *Note
mysql-proxy-scripting-structures-response::.

*Proxy Return State Constants*

The following constants are used internally by the proxy to specify the
response to send to the client or server. All constants are exposed as
values within the main `proxy' table.

Constant               Description
`PROXY_SEND_QUERY'     Causes the proxy to send the current contents of
                       the queries queue to the server.
`PROXY_SEND_RESULT'    Causes the proxy to send a result set back to the
                       client.
`PROXY_IGNORE_RESULT'  Causes the proxy to drop the result set (nothing
                       is returned to the client).

As constants, these entities are available without qualification in the
Lua scripts. For example, at the end of the `read_query_result()' you
might return `PROXY_IGNORE_RESULT:'

     return proxy.PROXY_IGNORE_RESULT

*Packet State Constants*

The following states describe the status of a network packet.  These
items are entries within the main `proxy' table.

Constant               Description
`MYSQLD_PACKET_OK'     The packet is OK.
`MYSQLD_PACKET_ERR'    The packet contains error information.
`MYSQLD_PACKET_RAW'    The packet contains raw data.

*Backend State/Type Constants*

The following constants are used either to define the status of the
backend server (the MySQL server to which the proxy is connected) or
the type of backend server. These items are entries within the main
`proxy' table.

Constant               Description
`BACKEND_STATE_UNKNOWN'The current status is unknown.
`BACKEND_STATE_UP'     The backend is known to be up (available).
`BACKEND_STATE_DOWN'   The backend is known to be down (unavailable).
`BACKEND_TYPE_UNKNOWN' Backend type is unknown.
`BACKEND_TYPE_RW'      Backend is available for read/write.
`BACKEND_TYPE_RO'      Backend is available only for read-only use.

*Server Command Constants*

The following values are used in the packets exchanged between the
client and server to identify the information in the rest of the
packet. These items are entries within the main `proxy' table. The
packet type is defined as the first character in the sent packet. For
example, when intercepting packets from the client to edit or monitor a
query you would check that the first byte of the packet was of type
`proxy.COM_QUERY'.

Constant               Description
`COM_SLEEP'            Sleep
`COM_QUIT'             Quit
`COM_INIT_DB'          Initialize database
`COM_QUERY'            Query
`COM_FIELD_LIST'       Field List
`COM_CREATE_DB'        Create database
`COM_DROP_DB'          Drop database
`COM_REFRESH'          Refresh
`COM_SHUTDOWN'         Shutdown
`COM_STATISTICS'       Statistics
`COM_PROCESS_INFO'     Process List
`COM_CONNECT'          Connect
`COM_PROCESS_KILL'     Kill
`COM_DEBUG'            Debug
`COM_PING'             Ping
`COM_TIME'             Time
`COM_DELAYED_INSERT'   Delayed insert
`COM_CHANGE_USER'      Change user
`COM_BINLOG_DUMP'      Binlog dump
`COM_TABLE_DUMP'       Table dump
`COM_CONNECT_OUT'      Connect out
`COM_REGISTER_SLAVE'   Register slave
`COM_STMT_PREPARE'     Prepare server-side statement
`COM_STMT_EXECUTE'     Execute server-side statement
`COM_STMT_SEND_LONG_DATA'Long data
`COM_STMT_CLOSE'       Close server-side statement
`COM_STMT_RESET'       Reset statement
`COM_SET_OPTION'       Set option
`COM_STMT_FETCH'       Fetch statement
`COM_DAEMON'           Daemon (MySQL 5.1 only)
`COM_ERROR'            Error

*MySQL Type Constants*

These constants are used to identify the field types in the query
result data returned to clients from the result of a query. These items
are entries within the main `proxy' table.

Constant               Field Type
`MYSQL_TYPE_DECIMAL'   Decimal
`MYSQL_TYPE_NEWDECIMAL'Decimal (MySQL 5.0 or later)
`MYSQL_TYPE_TINY'      Tiny
`MYSQL_TYPE_SHORT'     Short
`MYSQL_TYPE_LONG'      Long
`MYSQL_TYPE_FLOAT'     Float
`MYSQL_TYPE_DOUBLE'    Double
`MYSQL_TYPE_NULL'      Null
`MYSQL_TYPE_TIMESTAMP' Timestamp
`MYSQL_TYPE_LONGLONG'  Long long
`MYSQL_TYPE_INT24'     Integer
`MYSQL_TYPE_DATE'      Date
`MYSQL_TYPE_TIME'      Time
`MYSQL_TYPE_DATETIME'  Datetime
`MYSQL_TYPE_YEAR'      Year
`MYSQL_TYPE_NEWDATE'   Date (MySQL 5.0 or later)
`MYSQL_TYPE_ENUM'      Enumeration
`MYSQL_TYPE_SET'       Set
`MYSQL_TYPE_TINY_BLOB' Tiny Blob
`MYSQL_TYPE_MEDIUM_BLOB'Medium Blob
`MYSQL_TYPE_LONG_BLOB' Long Blob
`MYSQL_TYPE_BLOB'      Blob
`MYSQL_TYPE_VAR_STRING'Varstring
`MYSQL_TYPE_STRING'    String
`MYSQL_TYPE_TINY'      Tiny (compatible with `MYSQL_TYPE_CHAR)'
`MYSQL_TYPE_ENUM'      Enumeration (compatible with
                       `MYSQL_TYPE_INTERVAL')
`MYSQL_TYPE_GEOMETRY'  Geometry
`MYSQL_TYPE_BIT'       Bit


File: manual.info,  Node: mysql-proxy-scripting-connect-server,  Next: mysql-proxy-scripting-read-handshake,  Prev: mysql-proxy-scripting-structures,  Up: mysql-proxy-scripting

17.4.3 Capturing a connection with `connect_server()'
-----------------------------------------------------

When the proxy accepts a connection from a MySQL client, the
`connect_server()' function is called.

There are no arguments to the function, but you can use and if
necessary manipulate the information in the `proxy.connection' table,
which is unique to each client session.

For example, if you have multiple backend servers then you can set the
server to be used by that connection by setting the value of
`proxy.connection.backend_ndx' to a valid server number. The code below
will choose between two servers based on whether the current time in
minutes is odd or even:

     function connect_server()
             print("--> a client really wants to talk to a server")
             if (tonumber(os.date("%M")) % 2 == 0) then
                     proxy.connection.backend_ndx = 2
                     print("Choosing backend 2")
             else
                     proxy.connection.backend_ndx = 1
                     print("Choosing backend 1")
             end
             print("Using " .. proxy.backends[proxy.connection.backend_ndx].address)
     end

In this example the IP address/port combination is also displayed by
accessing the information from the internal `proxy.backends' table.


File: manual.info,  Node: mysql-proxy-scripting-read-handshake,  Next: mysql-proxy-scripting-read-auth,  Prev: mysql-proxy-scripting-connect-server,  Up: mysql-proxy-scripting

17.4.4 Examining the handshake with `read_handshake()'
------------------------------------------------------

Handshake information is sent by the server to the client after the
initial connection (through `connect_server()') has been made. The
handshake information contains details about the MySQL version, the ID
of the thread that will handle the connection information, and the IP
address of the client and server. This information is exposed through a
Lua table as the only argument to the function.

   * `mysqld_version' -- the version of the MySQL server.

   * `thread_id' -- the thread ID.

   * `scramble' -- the password scramble buffer.

   * `server_addr' -- the IP address of the server.

   * `client_addr' -- the IP address of the client.

For example, you can print out the handshake data and refuse clients by
IP address with the following function:

     function read_handshake( auth )
             print("<-- let's send him some information about us")
             print("    mysqld-version: " .. auth.mysqld_version)
             print("    thread-id     : " .. auth.thread_id)
             print("    scramble-buf  : " .. string.format("%q", auth.scramble))
             print("    server-addr   : " .. auth.server_addr)
             print("    client-addr   : " .. auth.client_addr)

             if not auth.client_addr:match("^127.0.0.1:") then
                     proxy.response.type = proxy.MYSQLD_PACKET_ERR
                     proxy.response.errmsg = "only local connects are allowed"

                     print("we don't like this client");

                     return proxy.PROXY_SEND_RESULT
             end
     end

Note that you have to return an error packet to the client by using
`proxy.PROXY_SEND_RESULT'.


File: manual.info,  Node: mysql-proxy-scripting-read-auth,  Next: mysql-proxy-scripting-read-auth-result,  Prev: mysql-proxy-scripting-read-handshake,  Up: mysql-proxy-scripting

17.4.5 Examining the authentication credentials with `read_auth()'
------------------------------------------------------------------

The `read_auth()' function is triggered when an authentication
handshake is initiated by the client. In the execution sequence,
`read_auth()' occurs immediately after `read_handshake()', so the
server selection has already been made, but the connection and
authorization information has not yet been provided to the backend
server.

The function accepts a single argument, an Lua table containing the
authorization information for the handshake process. The entries in the
table are:

   * `username' -- the user login for connecting to the server.

   * `password' -- the password, encrypted, to be used when connecting.

   * `default_db' -- the default database to be used once the
     connection has been made.

For example, you can print the username and password supplied during
authorization using:

     function read_auth( auth )
             print("    username      : " .. auth.username)
             print("    password      : " .. string.format("%q", auth.password))
     end

You can interrupt the authentication process within this function and
return an error packet back to the client by constructing a new packet
and returning `proxy.PROXY_SEND_RESULT':

     proxy.response.type = proxy.MYSQLD_PACKET_ERR
     proxy.response.errmsg = "Logins are not allowed"
     return proxy.PROXY_SEND_RESULT


File: manual.info,  Node: mysql-proxy-scripting-read-auth-result,  Next: mysql-proxy-scripting-read-query,  Prev: mysql-proxy-scripting-read-auth,  Up: mysql-proxy-scripting

17.4.6 Accessing authentication information with `read_auth_result()'
---------------------------------------------------------------------

The return packet from the server during authentication is captured by
`read_auth_result()'. The only argument to this function is the
authentication packet returned by the server. As the packet is a raw
MySQL network protocol packet, you must access the first byte to
identify the packet type and contents. The `MYSQLD_PACKET_ERR' and
`MYSQLD_PACKET_OK' constants can be used to identify whether the
authentication was successful:

     function read_auth_result( auth )
             local state = auth.packet:byte()

             if state == proxy.MYSQLD_PACKET_OK then
                     print("<-- auth ok");
             elseif state == proxy.MYSQLD_PACKET_ERR then
                     print("<-- auth failed");
             else
                     print("<-- auth ... don't know: " .. string.format("%q", auth.packet));
             end
     end


File: manual.info,  Node: mysql-proxy-scripting-read-query,  Next: mysql-proxy-scripting-read-query-result,  Prev: mysql-proxy-scripting-read-auth-result,  Up: mysql-proxy-scripting

17.4.7 Manipulating Queries with `read_query()'
-----------------------------------------------

The `read_query()' function is called once for each query submitted by
the client and accepts a single argument, the query packet that was
provided. To access the content of the packet you must parse the packet
contents manually.

For example, you can intercept a query packet and print out the
contents using the following function definition:

     function read_query( packet )
             if packet:byte() == proxy.COM_QUERY then
                     print("we got a normal query: " .. packet:sub(2))
             end
     end

This example checks the first byte of the packet to determine the type.
If the type is `COM_QUERY' (see *Note
mysql-proxy-scripting-structures-command-constants::), then we extract
the query from the packet and print it out. The structure of the packet
type supplied is important. In the case of a `COM_QUERY' packet, the
remaining contents of the packet are the text of the query string. In
this example, no changes have been made to the query or the list of
queries that will ultimately be sent to the MySQL server.

To modify a query, or add new queries, you must populate the query
queue (`proxy.queries') and then execute the queries that you have
placed into the queue. If you do not modify the original query or the
queue, then the query received from the client is sent to the MySQL
server verbatim.

When adding queries to the queue, you should follow these guidelines:

   * The packets inserted into the queue must be valid query packets.
     For each packet, you must set the initial byte to the packet type.
     If you are appending a query, you can append the query statement
     to the rest of the packet.

   * Once you add a query to the queue, the queue is used as the source
     for queries sent to the server. If you add a query to the queue to
     add more information, you must also add the original query to the
     queue or it will not be executed.

   * Once the queue has been populated, you must set the return value
     from `read_query()' to indicate whether the query queue should be
     sent to the server.

   * When you add queries to the queue, you should add an ID. The ID
     you specify is returned with the result set so that you identify
     each query and corresponding result set. The ID has no other
     purpose than as an identifier for correlating the query and
     resultset. When operating in a passive mode, during profiling for
     example, you want to identify the original query and the
     corresponding resultset so that the results expect by the client
     can be returned correctly.

   * Unless your client is designed to cope with more result sets than
     queries, you should ensure that the number of queries from the
     client match the number of results sets returned to the client.
     Using the unique ID and removing result sets you inserted will
     help.

Normally, the `read_query()' and `read_query_result()' function are
used in conjunction with each other to inject additional queries and
remove the additional result sets. However, `read_query_result()' is
only called if you populate the query queue within `read_query()'.


File: manual.info,  Node: mysql-proxy-scripting-read-query-result,  Prev: mysql-proxy-scripting-read-query,  Up: mysql-proxy-scripting

17.4.8 Manipulating Results with `read_query_result()'
------------------------------------------------------

The `read_query_result()' is called for each result set returned by the
server only if you have manually injected queries into the query queue.
If you have not manipulated the query queue then this function is not
called.  The function supports a single argument, the result packet,
which provides a number of properties:

   * `id' -- the ID of the result set, which corresponds to the ID that
     was set when the query packet was submitted to the server when
     using `append(id)' on the query queue.

   * `query' -- the text of the original query.

   * `query_time' -- the number of microseconds required to receive the
     first row of a result set.

   * `response_time' -- the number of microseconds required to receive
     the last row of the result set.

   * `resultset' -- the content of the result set data.

By accessing the result information from the MySQL server you can
extract the results that match the queries that you injected, return
different result sets (for example, from a modified query), and even
create your own result sets.

The Lua script below, for example, will output the query, followed by
the query time and response time (i.e. the time to execute the query
and the time to return the data for the query) for each query sent to
the server:

     function read_query( packet )
             if packet:byte() == proxy.COM_QUERY then
                     print("we got a normal query: " .. packet:sub(2))

                     proxy.queries:append(1, packet )

                     return proxy.PROXY_SEND_QUERY
             end
     end

     function read_query_result(inj)
             print("query-time: " .. (inj.query_time / 1000) .. "ms")
             print("response-time: " .. (inj.response_time / 1000) .. "ms")
     end

You can access the rows of returned results from the resultset by
accessing the rows property of the resultset property of the result
that is exposed through `read_query_result()'. For example, you can
iterate over the results showing the first column from each row using
this Lua fragment:

     for row in inj.resultset.rows do
             print("injected query returned: " .. row[1])
     end

Just like `read_query()', `read_query_result()' can return different
values for each result according to the result returned. If you have
injected additional queries into the query queue, for example, then you
will want to remove the results returned from those additional queries
and only return the results from the query originally submitted by the
client.

The example below injects additional `SELECT NOW()' statements into the
query queue, giving them a different ID to the ID of the original
query. Within `read_query_result()', if the ID for the injected queries
is identified, we display the result row, and return the
`proxy.PROXY_IGNORE_RESULT' from the function so that the result is not
returned to the client. If the result is from any other query, we print
out the query time information for the query and return the default,
which passes on the result set unchanged. We could also have explicitly
returned `proxy.PROXY_IGNORE_RESULT' to the MySQL client.

     function read_query( packet )
             if packet:byte() == proxy.COM_QUERY then
                     proxy.queries:append(2, string.char(proxy.COM_QUERY) .. "SELECT NOW()" )
                     proxy.queries:append(1, packet )
                     proxy.queries:append(2, string.char(proxy.COM_QUERY) .. "SELECT NOW()" )

                     return proxy.PROXY_SEND_QUERY
             end
     end

     function read_query_result(inj)
             if inj.id == 2 then
                     for row in inj.resultset.rows do
                             print("injected query returned: " .. row[1])
                     end
                     return proxy.PROXY_IGNORE_RESULT
             else
                     print("query-time: " .. (inj.query_time / 1000) .. "ms")
                     print("response-time: " .. (inj.response_time / 1000) .. "ms")
             end
     end

For further examples, see *Note mysql-proxy-using::.


File: manual.info,  Node: mysql-proxy-using,  Next: mysql-proxy-faq,  Prev: mysql-proxy-scripting,  Up: mysql-proxy

17.5 Using MySQL Proxy
======================

* Menu:

* mysql-proxy-using-admin::      Using the Administration Interface

There are a number of different ways to use MySQL Proxy. At the most
basic level, you can allow MySQL Proxy to pass on queries from clients
to a single server. To use MySQL proxy in this mode, you just have to
specify the backend server that the proxy should connect to on the
command line:

     $ mysql-proxy --proxy-backend-addresses=sakila:3306

If you specify multiple backend MySQL servers then the proxy will
connect each client to each server in a round-robin fashion. For
example, imagine you have two MySQL servers, A and B. The first client
to connect will be connected to server A, the second to server B, the
third to server C. For example:

     $ mysql-proxy \
          --proxy-backend-addresses=narcissus:3306 \
          --proxy-backend-addresses=nostromo:3306

When you have specified multiple servers in this way, the proxy will
automatically identify when a MySQL server has become unavailable and
mark it accordingly. New connections will automatically be attached to
a server that is available, and a warning will be reported to the
standard output from `mysql-proxy':

     network-mysqld.c.367: connect(nostromo:3306) failed: Connection refused
     network-mysqld-proxy.c.2405: connecting to backend (nostromo:3306) failed, marking it as down for ...

Lua scripts enable a finer level of control, both over the connections
and their distribution and how queries and result sets are processed.
When using an Lua script, you must specify the name of the script on
the command line using the `--proxy-lua-script' option:

     $ mysql-proxy --proxy-lua-script=mc.lua --proxy-backend-addresses=sakila:3306

When you specify a script, the script is not executed until a
connection is made. This means that faults with the script will not be
raised until the script is executed. Script faults will not affect the
distribution of queries to backend MySQL servers.

*Note*:

Because the script is not read until the connection is made, you can
modify the contents of the Lua script file while the proxy is still
running and the script will automatically be used for the next
connection. This ensures that MySQL Proxy remains available because it
does not have to be restarted for the changes to take effect.


File: manual.info,  Node: mysql-proxy-using-admin,  Prev: mysql-proxy-using,  Up: mysql-proxy-using

17.5.1 Using the Administration Interface
-----------------------------------------

The `mysql-proxy' administration interface can be accessed using any
MySQL client using the standard protocols.  You can use the
administration interface to gain information about the proxy server as
a whole - standard connections to the proxy are isolated to operate as
if you were connected directly to the backend MySQL server. Currently,
the interface supports a limited set of functionality designed to
provide connection and configuration information.

Because connectivity is provided over the standard MySQL protocol, you
must access this information using SQL syntax. By default, the
administration port is configured as 4041. You can change this port
number using the `--admin-address' command-line option.

To get a list of the currently active connections to the proxy:

     mysql> select * from proxy_connections;
     +------+--------+-------+------+
     | id   | type   | state | db   |
     +------+--------+-------+------+
     |    0 | server | 0     |      |
     |    1 | proxy  | 0     |      |
     |    2 | server | 10    |      |
     +------+--------+-------+------+
     3 rows in set (0.00 sec)

To get the current configuration:

     mysql> select * from proxy_config;
     +----------------------------+----------------------+
     | option                     | value                |
     +----------------------------+----------------------+
     | admin.address              | :4041                |
     | proxy.address              | :4040                |
     | proxy.lua_script           | mc.lua               |
     | proxy.backend_addresses[0] | mysql:3306           |
     | proxy.fix_bug_25371        | 0                    |
     | proxy.profiling            | 1                    |
     +----------------------------+----------------------+
     6 rows in set (0.01 sec)


File: manual.info,  Node: mysql-proxy-faq,  Prev: mysql-proxy-using,  Up: mysql-proxy

17.6 MySQL Proxy FAQ
====================

*Questions*
   * 18.6.1: Is the system context switch expensive, how much overhead
     does the lua script add?

   * 18.6.2: How do I use a socket with MySQL Proxy? Proxy change logs
     mention that support for UNIX sockets has been added.

   * 18.6.3: If MySQL Proxy has to live on same machine as MySQL, are
     there any tuning considerations to ensure both perform optimally?

   * 18.6.4: Do proxy applications run on a separate server? If not,
     what is the overhead incurred by Proxy on the DB server side?

   * 18.6.5: Can MySQL Proxy handle SSL connections?

   * 18.6.6: What is the limit for `max-connections' on the server?

   * 18.6.7: With load balancing, what happen to transactions ? Are all
     queries sent to the same server ?

   * 18.6.8: Can I run MySQL Proxy as a daemon?

   * 18.6.9: What about caching the authorization info so clients
     connecting are given back-end connections that were established
     with identical authorization information, thus saving a few more
     round trips?

   * 18.6.10: Could MySQL Proxy be used to capture passwords?

   * 18.6.11: Can MySQL Proxy be used on slaves and intercept binlog
     messages?

   * 18.6.12: As the script is re-read by proxy, does it cache this or
     is it looking at the filesystem with each request?

   * 18.6.13: MySQL Proxy can handle about 5000 connections, what is
     the limit on a MySQL server?

   * 18.6.14: How does MySQL Proxy compare to DBSlayer ?

   * 18.6.15: I currently use SQL Relay for efficient connection
     pooling with a number of apache processes connecting to a MySQL
     server. Can MySQL proxy currently accomplish this. My goal is to
     minimize connection latency while keeping temporary tables
     available.

   * 18.6.16: The global namespace variable example with quotas does not
     persist after a reboot, is that correct?

   * 18.6.17: I tried using MySQL Proxy without any Lua script to try a
     round-robin type load balancing. In this case, if the first
     database in the list is down, MySQL Proxy would not connect the
     client to the second database in the list.

   * 18.6.18: Would the Java-only connection pooling solution work for
     multiple web servers? With this, I'd assume you can pool across
     many web servers at once?

   * 18.6.19: Is the MySQL Proxy an API ?

   * 18.6.20: If you have multiple databases on the same box, can you
     use proxy to connect to databases on default port 3306?

   * 18.6.21: Will Proxy be deprecated for use with connection pooling
     once MySQL 6.x comes out? Or will 6.x integrate proxy more deeply?

   * 18.6.22: We've looked at using MySQL Proxy but we're concerned
     about the alpha status - when do you think the proxy would be
     considered production ready?

   * 18.6.23: Will the proxy road map involve moving popular features
     from lua to C? For example Read/Write splitting

   * 18.6.24: In load balancing, how can I separate reads from writes?
     Is a backend-server a remote MySQL machine ? You would think so,
     but from another post in this forum, it looks like the separation
     of reads from writes has not been implemented yet, so I am not
     clear as to the distinction between backend-servers and read-only
     servers.

          $ mysql-proxy \
          --proxy-backend-addresses=10.0.1.2:3306 \
          --proxy-backend-addresses=10.0.1.3:3306 &

     I don't see how this works for writes, as they have to go to the
     master server.

   * 18.6.25: Are these reserved function names (e.g., error_result)
     that get automatically called?

   * 18.6.26: Can you explain the status of your work with `memcached'
     and MySQL Proxy?

   * 18.6.27: Is there any big web site using MySQL Proxy ? For what
     purpose and what transaction rate have they achieved.

   * 18.6.28: So the authentication when connection pooling has to be
     done at every connection? What's the authentication latency?

   * 18.6.29: Is it possible to use the MySQL proxy w/ updating a
     Lucene index (or Solr) by making TCP calls to that server to
     update?

   * 18.6.30: Isn't MySQL Proxy similar to what is provided by Java
     connection pools?

   * 18.6.31: Are there tools for isolating problems? How can someone
     figure out if a problem is in the client, in the db or in the
     proxy?

   * 18.6.32: Can you dynamically reconfigure the pool of MySQL servers
     that MySQL Proxy will load balance to?

   * 18.6.33: Given that there is a `connect_server' function, can a
     Lua script link up with multiple servers?

   * 18.6.34: Adding a proxy must add latency to the connection, how
     big is that latency?

   * 18.6.35: In the quick poll, I see "Load Balancer: read-write
     splitting" as an option, so would it be correct to say that there
     are no scripts written for Proxy yet to do this?

   * 18.6.36: Is it "safe" to use `LuaSocket' with proxy scripts?

   * 18.6.37: How different is MySQL Proxy from DBCP (Database
     connection pooling) for Apache in terms of connection pooling?

   * 18.6.38: Do you have make one large script and call at proxy
     startup, can I change scripts without stopping and restarting
     (interrupting) the proxy?

*Questions and Answers* *18.6.1: ** Is the system context switch
expensive, how much overhead does the lua script add?  *

Lua is fast and the overhead should be small enough for most
applications. The raw packet-overhead is around 400 microseconds.

*18.6.2: ** How do I use a socket with MySQL Proxy? Proxy change logs
mention that support for UNIX sockets has been added.  *

Just specify the path to the socket:

     --proxy-backend-addresses=/path/to/socket

However it appears that `--proxy-address=/path/to/socket' does not work
on the front end. It would be nice if someone added this feature.

*18.6.3: ** If MySQL Proxy has to live on same machine as MySQL, are
there any tuning considerations to ensure both perform optimally?  *

MySQL Proxy can live on any box: application, db or its own box.  MySQL
Proxy uses comparatively little CPU or RAM, so additional requirements
or overhead is negligible.

*18.6.4: ** Do proxy applications run on a separate server? If not,
what is the overhead incurred by Proxy on the DB server side?  *

You can run the proxy on the application server, on its own box or on
the DB-server depending on the use-case

*18.6.5: ** Can MySQL Proxy handle SSL connections?  *

No, being the man-in-the-middle, Proxy can't handle encrypted sessions
because it cannot share the SSL information.

*18.6.6: ** What is the limit for `max-connections' on the server?  *

Around 1024 connections the MySQL Server may run out of threads it can
spawn. Leaving it at around 100 is advised.

*18.6.7: ** With load balancing, what happen to transactions ? Are all
queries sent to the same server ?  *

Without any special customization the whole connection is sent to the
same server. That keeps the whole connection state intact.

*18.6.8: ** Can I run MySQL Proxy as a daemon?  *

Starting from version 0.6.0, the Proxy is launched as a daemon by
default. If you want to avoid this, use the `-D' or `--no-daemon'
option.  To keep track of the process ID, the daemon can be started with
the additional option `--pid-file=file', to save the PID to a known
file name. On version 0.5.x, the Proxy can't be started natively as a
daemon

*18.6.9: ** What about caching the authorization info so clients
connecting are given back-end connections that were established with
identical authorization information, thus saving a few more round trips?
*

There is an option that provides this functionality `
--proxy-pool-no-change-user'.

*18.6.10: ** Could MySQL Proxy be used to capture passwords?  *

The MySQL network protocol does not allow passwords to be sent in
clear-text, all you could capture is the encrypted version.

*18.6.11: ** Can MySQL Proxy be used on slaves and intercept binlog
messages?  *

We are working on that. See
`http://jan.kneschke.de/2008/5/30/mysql-proxy-rbr-to-sbr-decoding' for
an example.

*18.6.12: ** As the script is re-read by proxy, does it cache this or
is it looking at the filesystem with each request?  *

It looks for the script at client-connect and reads it if it has
changed, otherwise it uses the cached version.

*18.6.13: ** MySQL Proxy can handle about 5000 connections, what is the
limit on a MySQL server?  *

Se your `max-connections' settings. By default the setting is 150, the
proxy can handle a lot more.

*18.6.14: ** How does MySQL Proxy compare to DBSlayer ?  *

DBSlayer is a REST->MySQL tool, MySQL Proxy is transparent to your
application. No change to the application is needed.

*18.6.15: ** I currently use SQL Relay for efficient connection pooling
with a number of apache processes connecting to a MySQL server. Can
MySQL proxy currently accomplish this. My goal is to minimize
connection latency while keeping temporary tables available.  *

Yes.

*18.6.16: ** The global namespace variable example with quotas does not
persist after a reboot, is that correct?  *

Yes. if you restart the proxy, you lose the results, unless you save
them in a file.

*18.6.17: ** I tried using MySQL Proxy without any Lua script to try a
round-robin type load balancing. In this case, if the first database in
the list is down, MySQL Proxy would not connect the client to the
second database in the list.  *

This issue is fixed in version 0.7.0.

*18.6.18: ** Would the Java-only connection pooling solution work for
multiple web servers? With this, I'd assume you can pool across many
web servers at once?  *

Yes. But you can also start one proxy on each application server to get
a similar behaviour as you have it already.

*18.6.19: ** Is the MySQL Proxy an API ?  *

No, MySQL Proxy is an application that forwards packets from a client
to a server using the MySQL network protocol. The MySQL proxy provides
a API allowing you to change its behaviour.

*18.6.20: ** If you have multiple databases on the same box, can you use
proxy to connect to databases on default port 3306?  *

Yes, MySQL Proxy can listen on any port. Providing none of the MySQL
servers are listening on the same port.

*18.6.21: ** Will Proxy be deprecated for use with connection pooling
once MySQL 6.x comes out? Or will 6.x integrate proxy more deeply?  *

The logic about the pooling is controlled by the lua scripts, you can
enable and disable it if you like. There are no plans to embed the
current MySQL Proxy functionality into the MySQL Server.

*18.6.22: ** We've looked at using MySQL Proxy but we're concerned
about the alpha status - when do you think the proxy would be considered
production ready?  *

We are on the road to the next feature release: 0.7.0. It will improve
the performance quite a bit. After that we may be able to enter the
beta phase.

*18.6.23: ** Will the proxy road map involve moving popular features
from lua to C? For example Read/Write splitting *

We will keep the high-level parts in the Lua layer to be able to adjust
to special situations without a rebuild. Read/Write splitting sometimes
needs external knowledge that may only be available by the DBA.

*18.6.24: ** In load balancing, how can I separate reads from writes?
Is a backend-server a remote MySQL machine ? You would think so, but
from another post in this forum, it looks like the separation of reads
from writes has not been implemented yet, so I am not clear as to the
distinction between backend-servers and read-only servers.  *
     $ mysql-proxy \
     --proxy-backend-addresses=10.0.1.2:3306 \
     --proxy-backend-addresses=10.0.1.3:3306 &
* I don't see how this works for writes, as they have to go to the
master server.  *

In version 0.6.0 there is no separation between read and writes and it
is up the user to make sure that only reads are sent to the proxy. In
the next releases we will add connection pooling and read/write
splitting to make this more useful. See also *Note load-balancer::.

*18.6.25: ** Are these reserved function names (e.g., error_result)
that get automatically called?  *

Only functions and values starting with `proxy.*' are provided by the
proxy. All others are provided by you.

*18.6.26: ** Can you explain the status of your work with `memcached'
and MySQL Proxy?  *

There are some ideas to integrate proxy and `memcache' a bit, but no
code yet.

*18.6.27: ** Is there any big web site using MySQL Proxy ? For what
purpose and what transaction rate have they achieved.  *

Yes, gaiaonline (http://gaiaonline.com/).  They have tested MySQL Proxy
and seen it handle 2400 queries per second through the proxy.

*18.6.28: ** So the authentication when connection pooling has to be
done at every connection? What's the authentication latency?  *

You can skip the round-trip and use the connection as it was added to
the pool. As long as the application cleans up the temporary tables it
used. The overhead is (as always) around 400 microseconds.

*18.6.29: ** Is it possible to use the MySQL proxy w/ updating a Lucene
index (or Solr) by making TCP calls to that server to update?  *

Yes, but it isn't advised for now.

*18.6.30: ** Isn't MySQL Proxy similar to what is provided by Java
connection pools?  *

Yes and no. Java connection pools are specific to Java applications,
MySQL Proxy works with any client API that talks the MySQL network
protocol. Also, connection pools do not provide any functionality for
intelligently examining the network packets and modifying the contents.

*18.6.31: ** Are there tools for isolating problems? How can someone
figure out if a problem is in the client, in the db or in the proxy?  *

You can set a debug script in the proxy, which is an exceptionally good
tool for this purpose. You can see very clearly which component is
causing the problem, if you set the right breakpoints.

*18.6.32: ** Can you dynamically reconfigure the pool of MySQL servers
that MySQL Proxy will load balance to?  *

Not yet, it is on the list. We are working on a administration
interface for that purpose.

*18.6.33: ** Given that there is a `connect_server' function, can a Lua
script link up with multiple servers?  *

The proxy provides some tutorials in the source-package, one is
`examples/tutorial-keepalive.lua'.

*18.6.34: ** Adding a proxy must add latency to the connection, how big
is that latency?  *

In the range of 400microseconds

*18.6.35: ** In the quick poll, I see "Load Balancer: read-write
splitting" as an option, so would it be correct to say that there are no
scripts written for Proxy yet to do this?  *

There is a proof of concept script for that included. But its far from
perfect and may not work for you yet.

*18.6.36: ** Is it "safe" to use `LuaSocket' with proxy scripts?  *

You can, but it is not advised as it may block.

*18.6.37: ** How different is MySQL Proxy from DBCP (Database connection
pooling) for Apache in terms of connection pooling?  *

Connection Pooling is just one use-case of the MySQL Proxy. You can use
it for a lot more and it works in cases where you can't use DBCP (like
if you don't have Java).

*18.6.38: ** Do you have make one large script and call at proxy
startup, can I change scripts without stopping and restarting
(interrupting) the proxy?  *

You can just change the script and the proxy will reload it when a
client connects.


File: manual.info,  Node: load-balancer,  Next: replication,  Prev: mysql-proxy,  Up: Top

18 MySQL Load Balancer
**********************

* Menu:

* mysql-lb-installing::          Installing MySQL Load Balancer
* mysql-lb-getting-started::     Getting Started
* mysql-lb-using::               Using MySQL Load Balancer
* mysql-lb-known-issues::        Known Issues
* load-balancer-faq::            MySQL Load Balancer FAQ

*Important*:

For more information on MySQL Load Balancer, including how to be
included in the beta programme, contact <enterprise-beta@mysql.com>.

The MySQL Load Balancer is an application that communicates with one or
more MySQL servers and provides connectivity to those servers for
multiple clients. The MySQL Load Balancer is logically placed between
the clients and the MySQL server; instead of clients connecting
directly to each MySQL server, all clients connect to the MySQL Load
Balancer, and the MySQL Load Balancer forwards the connection on to one
of the MySQL servers.

The initial release of the MySQL Load Balancer provides read-only load
balancing over a number of MySQL servers. Initially, you populate the
MySQL Load Balancer configuration with the list of available MySQL
servers to use when distributing work. The MySQL Load Balancer
automatically and evenly distributes connections from clients to each
server. Distribution is handled by a simple count for the number
connections distributed to each server - new connections are
automatically sent to the server with the lowest count.

When used in combination with a replication setup, the MySQL Load
Balancer also monitors the replication status. The master and slaves
within the replication setup are monitored and additional decisions
about the routing of incoming connections to MySQL servers are made
based on the replication status:

   * If MySQL Load Balancer identifies that the slave is lagging behind
     the master for it's replication threads, then the slave is
     automatically taken out of the list of available servers.  Work
     will therefore be distributed to other MySQL servers within the
     slave replication group.

   * If the replication thread on a slave is identified as no longer
     running, the slave is also automatically removed from the list of
     available servers.

   * If either situation changes, such as the replication delay
     decreases to an acceptable level, or the replication thread on the
     failed slave is restarted and the replication process catches up,
     then the slave will be brought back in to the list of available
     MySQL servers.

The MySQL Load Balancer is based on the MySQL Proxy, and consists of
two modules which work together to achieve its goal:

   * The _proxy_, which uses Lua scripts to customize the handling of
     connections and query execution. The `proxy` connects to several
     backend MySQL instances to which it can send queries.

   * The _monitor_ plugin connects to each of the backends the proxy
     knows about and executes queries on each one in regular intervals.
     The results of those queries are used to determine the state of
     each backend.

For more information on MySQL Proxy, see *Note mysql-proxy::.


File: manual.info,  Node: mysql-lb-installing,  Next: mysql-lb-getting-started,  Prev: load-balancer,  Up: load-balancer

18.1 Installing MySQL Load Balancer
===================================

*Important*:

For more information on MySQL Load Balancer, including how to be
included in the beta programme, contact <enterprise-beta@mysql.com>.

MySQL Load Balancer is provided as a TAR/GZipped package. To install,
extract the package:

     $ gzip -cd load-balancer mysql-load-balancer-0.7.0-438-linux-fc4-x86-32bit.tar.gz | tar xf -

The standard package contents are organized into four directories:

     /bin
     /lib
     /sbin
     /share

The `bin' contains wrapper scripts around the dynamically linked
binaries in `sbin'. The `lib' directory contains the required
libraries, and the `share' directory contains the scripts and support
files used by the MySQL Load Balancer during execution.

You can run MySQL Load Balancer directly from this directory, or you
can copy the contents to a a global directory, such as `/usr/local':

     $ cp -R * /usr/local/


File: manual.info,  Node: mysql-lb-getting-started,  Next: mysql-lb-using,  Prev: mysql-lb-installing,  Up: load-balancer

18.2 Getting Started
====================

*Important*:

For more information on MySQL Load Balancer, including how to be
included in the beta programme, contact <enterprise-beta@mysql.com>.

The easiest way to understand MySQL Load Balancer is to look at a
typical example of how MySQL Load Balancer can be used to improve the
distribution of work to multiple MySQL servers.

Given an existing setup of several replicating MySQL servers, you can
set up the MySQL Load Balancer to provide you with replication-aware
load distribution.

Suppose you have three slaves replicating from one master, the slaves
running on the machines _slave-1_, _slave-2_, and _slave-3_, the master
being on _master-1_. Each MySQL server listens on the default port of
3306.

For client connectivity, typical configurations are in one of two
topologies. The first topology uses applications that are aware of
multiple clients and choose a MySQL server based either on a random
selection or by choosing a slave based on a known quantity, such as
user ID.

FIGURE GOES HERE: Replication architecture with clients using multiple
MySQL slaves

In this scenario, it is possible for a client application to choose a
slave that is unavailable, or in a replication situation, a slave that
is not up to date compared to the master, or lagging behind the master
in terms of processing replication data such that queries accessing the
information would fail to return data, or return data that was out of
date. In all these cases, the client would be unable to determine the
issue (without checking the situation itself). In the event of a failed
server, the connection would timeout and another server could be
chosen, but the delay could cause problems in the application.

In this scenario, it is also possible for a single MySQL server to
become overloaded with requests. For example, if the application was
using an ID-based decision model to choose a MySQL server, then a high
number of requests for a given ID could produce a very high load on the
chosen server. This could affect the replication thread and place the
server further behind compared to the master.

The second topology uses a model where each client has a dedicated
MySQL server.

FIGURE GOES HERE: Replication architecture with clients using dedicated
MySQL slaves

In this scenario, a problem with the MySQL server for an individual
client could render the client useless. If the MySQL server is
significantly behind the master, you would get out of date or incorrect
information. If the MySQL server has failed, the client will be unable
to access any information.

Using the MySQL Load Balancer, you can replace the individual
connections from the clients to the slaves and instead route the
connections through the MySQL Load Balancer. This will distribute the
requests over the individual slave servers, automatically taking
account of the load, and accounting for problems or delays in the
replication of the data from the master.

FIGURE GOES HERE: Replication architecture with clients using MySQL
Load Balancer

In the scenario using MySQL Load Balancer, any failure of a single
MySQL server automatically removes it from the pool of available
servers and distributes the incoming client connection to one of the
other, available, servers. Problems with replication are addressed in
the same way, redirecting the connection to a server that is up to date
with the master. The possibility of overloading a single MySQL server
should also be reduced, since the connections would be distributed
evenly among each server.

To start the MySQL Load Balancer in this scenario you would specify the
configuration of the master and slave servers on the command line when
starting `mysql-lb':

     $ bin/mysql-lb --proxy-backend-addresses=master-1 \
       --proxy-read-only-backend-addresses=slave-1:3306 \
       --proxy-read-only-backend-addresses=slave-2:3306 \
       --proxy-read-only-backend-addresses=slave-3:3306 \
       --proxy-lua-script=share/mysql-load-balancer/monitored-ro-balance.lua \
       --monitor-lua-script=share/mysql-load-balancer/monitor-backends.lua

This will start the load balancer, which listens for incoming client
connections on port 4040. The monitor component will connect to each
backend MySQL server with the MySQL user `monitor' and no password, to
be able to execute queries on them. If you do not have a MySQL user
with that name or have a password set for the user, you can specify
those using the options `-monitor-username` and `-monitor-password`.

The options in this example set the following options:

   * `--proxy-backend-addresses' - sets the address and port number of
     the MySQL master server in the replication structure. This is
     required so that MySQL Load Balancer can monitor the status of the
     server and replication and use this to compare against the status
     of the slave servers. In the event of a problem, the information
     gained will be used to prioritse connections to the slaves
     according to which slave is the most up to date.

   * `--proxy-read-only-backend-addresses' - each one of these options
     sets the address and port number (separated by a colon), of a
     backend MySQL server. You can specify as many servers as you like
     on the command line simply by adding further options.

   * `--proxy-lua-script' - specifies the Lua script that will be used
     to manage to the distribution of requests.

   * `--monitor-lua-script' - specifies the Lua script that will be
     used to monitor the backends.

To get a list of all the available options, run

      $ mysql-lb --help-all


File: manual.info,  Node: mysql-lb-using,  Next: mysql-lb-known-issues,  Prev: mysql-lb-getting-started,  Up: load-balancer

18.3 Using MySQL Load Balancer
==============================

*Important*:

For more information on MySQL Load Balancer, including how to be
included in the beta programme, contact <enterprise-beta@mysql.com>.

When using the MySQL Load Balancer, you must adapt your application to
work with the connections provided by the MySQL Load Balancer
interface, rather than directly to MySQL servers.  The MySQL Load
Balancer supports the same MySQL network protocol - you do not need to
change the method that you use to communicate with MySQL. You can
continue to use the standard MySQL interface appropriate for your
application environment.

On each client, you should configure your application to connect to
port 4040 on the machine on which you started the MySQL Load Balancer.
All MySQL connections for _read_ queries should be sent to the MySQL
Load Balancer connection. When a client connects, the connection is
routed by MySQL Load Balancer to an appropriate MySQL server. All
subsequent queries on that connection will run be executed on the same
backed MySQL server.  The backend will not be changed after the
connection has been established.

If MySQL Load Balancer identifies an issue with the backend MySQL
server, then connections to the backend server are closed. Your
application should be adapted so that it can re-open a connection if it
closes during execution, re-executing the query again if there is
failure. MySQL Load Balancer will then choose a different MySQL server
for the new connection.

The thresholds with which the monitor considers a slave to be too far
behind are specified in the `monitor-backends.lua' file. By default it
checks for information obtained by `SHOW SLAVE STATUS', namely
`Seconds_Behind_Master' and tries to calculate the amount of data (in
bytes) the slave has to read from the master. The default values for
those metrics are 10 seconds and 10 kilobytes, respectively.

*Note*:

You need to restart the MySQL Load Balancer if you change the
`monitor-backends.lua' script while it is running. This is different
from MySQL Proxy, which automatically reloads a script if you modify
the script during execution.

The load balancing algorithm is specified in the
`monitored-ro-balance.lua' script. For this release, it keeps a counter
of how many queries each backend has executed and always picks the
backend with the least number of queries. Look at `connect_server()' and
`pick_ro_backend_least_queries()' for the code.


File: manual.info,  Node: mysql-lb-known-issues,  Next: load-balancer-faq,  Prev: mysql-lb-using,  Up: load-balancer

18.4 Known Issues
=================

*Important*:

For more information on MySQL Load Balancer, including how to be
included in the beta programme, contact <enterprise-beta@mysql.com>.

For this alpha release, there are the following known issues:

   * Sometimes an assertion in `libevent' fails when shutting down
     `mysql-lb'. The assertion failure occurs after all client and
     server connections have been closed already, thus is does not
     affect the normal operation of the program.

   * When using UNIX domain sockets to specify backends, it logs errors
     like: `network-mysqld.c.1648: can't convert addr-type 1 into a
     string' This is recorded as a Bug#35216
     (http://bugs.mysql.com/35216) and will be fixed in the next
     release. The implication is that the backend address is not
     available in the Lua scripts, it does not impair normal operations
     of the program.


File: manual.info,  Node: load-balancer-faq,  Prev: mysql-lb-known-issues,  Up: load-balancer

18.5 MySQL Load Balancer FAQ
============================

*Important*:

For more information on MySQL Load Balancer, including how to be
included in the beta programme, contact <enterprise-beta@mysql.com>.

The following section includes some common questions and answers for
MySQL Load Balancer:

*Questions*
   * 19.5.1: The current description says that the load balancer is for
     read-only operation. Does that mean that MySQL Load Balancer will
     not accept update statements for the slaves?

   * 19.5.2: The MSQL Load Balancer is listed as being 'slave state
     aware'. Do you check the status of both threads in the replication
     process.

   * 19.5.3: Is it possible to set the amount of acceptable lag?

   * 19.5.4: Does MySQL Load Balancer handle load balancing based on CPU
     load, memory load or I/O load?

*Questions and Answers* *19.5.1: ** The current description says that
the load balancer is for read-only operation. Does that mean that MySQL
Load Balancer will not accept update statements for the slaves?  *

No. Currently, the MySQL Load Balancer doesn't prevent you from making
modifications on the slaves. The read-only description is being used to
indicate that you should only use this solution for sending quries to
existing slave hosts.

*19.5.2: ** The MSQL Load Balancer is listed as being 'slave state
aware'. Do you check the status of both threads in the replication
process.  *

Yes. the monitor module runs `SHOW SLAVE STATUS' and checkes the status
of the replication process. If there is a problem, either because the
slave has lagged too far behind the master, or because the query thread
has stopped, then the slave will be taken out of the list of available
slaves for distributing queries.

*19.5.3: ** Is it possible to set the amount of acceptable lag?  *

Yes, you can set the lag time by editing the time within the load
balancer Lua script. Edit the file
`share/mysql-load-balancer/ro-balance.lua' and change the line:

     max_seconds_lag = 10,      -- 10 seconds

Altering the 10 seconds to the lag time that you want to support.

*19.5.4: ** Does MySQL Load Balancer handle load balancing based on CPU
load, memory load or I/O load?  *

Currently we use indirect measurements and balance the distribution of
queries by looking at the replication status of the slave nodes. Since
the distribution of work is written using Lua, it is possible to use a
number of different criteria. Using more complex criteria will be
possible in the future.


File: manual.info,  Node: replication,  Next: mysql-cluster,  Prev: load-balancer,  Up: Top

19 Replication
**************

* Menu:

* replication-configuration::    Replication Configuration
* replication-solutions::        Replication Solutions
* replication-notes::            Replication Notes and Tips
* replication-implementation::   Replication Implementation

Replication enables data from one MySQL database server (called the
master) to be replicated to one or more MySQL database servers
(slaves). Replication is asynchronous - your replication slaves do not
need to be connected permanently to receive updates from the master,
which means that updates can occur over long-distance connections and
even temporary solutions such as a dial-up service.  Depending on the
configuration, you can replicate all databases, selected databases and
even selected tables within a database.

The target uses for replication in MySQL include:

   * Scale-out solutions - spreading the load among multiple slaves to
     improve performance. In this environment, all writes and updates
     must take place on the master server. Reads, however, may take
     place on one or more slaves. This model can improve the
     performance of writes (since the master is dedicated to updates),
     while dramatically increasing read speed across an increasing
     number of slaves.

   * Data security - because data is replicated to the slave, and the
     slave can pause the replication process, it is possible to run
     backup services on the slave without corrupting the corresponding
     master data.

   * Analytics - live data can be created on the master, while the
     analysis of the information can take place on the slave without
     affecting the performance of the master.

   * Long-distance data distribution - if a branch office would like to
     work with a copy of your main data, you can use replication to
     create a local copy of the data for their use without requiring
     permanent access to the master.

Replication in MySQL features support for one-way, asynchronous
replication, in which one server acts as the master, while one or more
other servers act as slaves. This is in contrast to the _synchronous_
replication which is a characteristic of MySQL Cluster (see *Note
mysql-cluster::).

There are a number of solutions available for setting up replication
between two servers, but the best method to use depends on the presence
of data and the engine types you are using. For more information on the
available options, see *Note replication-howto::.

There are two core types of replication format, Statement Based
Replication (SBR), which replicates entire SQL statements, and Row
Based Replication (RBR), which replicates only the changed rows. You
may also use a third variety, Mixed Based Replication (MBR), which is
the default mode within MySQL 5.1.12 and later. For more information on
the different replication formats, see *Note replication-formats::.

Replication is controlled through a number of different options and
variables. These control the core operation of the replication,
timeouts and the databases and filters that can be applied on databases
and tables. For more information on the available options, see *Note
replication-options::.

You can use replication to solve a number of different problems,
including problems with performance, supporting the backup of different
databases and for use as part of a larger solution to alleviate system
failures. For information on how to address these issues, see *Note
replication-solutions::.

For notes and tips on how different data types and statements are
treated during replication, including details of replication features,
version compatibility, upgrades, and problems and their resolution,
including an FAQ, see *Note replication-notes::.

Detailed information on the implementation of replication, how
replication works, the process and contents of the binary log,
background threads and the rules used to decide how statements are
recorded and replication, see *Note replication-implementation::.

MySQL Enterprise

The MySQL Enterprise Monitor provides numerous advisors that provide
immediate feedback about replication-related problems. For more
information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: replication-configuration,  Next: replication-solutions,  Prev: replication,  Up: replication

19.1 Replication Configuration
==============================

* Menu:

* replication-howto::            How to Set Up Replication
* replication-formats::          Replication Formats
* replication-options::          Replication Options and Variables
* replication-administration::   Common Replication Administration Tasks

Replication between servers in MySQL works through the use of the
binary logging mechanism. The MySQL instance operating as the master
(the source of the database changes) writes updates and changes to the
database to the binary log. The information in the binary log is stored
in different logging formats according to the database changes being
recorded. Slaves are configured to read the binary log from the master
and to execute the events in the binary log on the slave's local
database.

The Master is dumb in this scenario. Once binary logging has been
enabled, all statements are recorded in the binary log. Each slave will
receive a copy of the entire contents of the binary log. It is the
responsibility of the slave to decide which statements in the binary
log should be executed; you cannot configure the master to log only
certain events. If you do not specify otherwise, all events in the
master binary log are executed on the slave. If required, you can
configure the slave to only process events that apply to particular
databases or tables.

Slaves keep a record of the binary log file and position within the log
file that they have read and processed from the master. This means that
multiple slaves can be connected to the master and executing different
parts of the same binary log. Because the slaves control this process,
individual slaves can be connected and disconnected from the server
without affecting the master's operation. Also, because each slave
remembers the position within the binary log, it is possible for slaves
to be disconnected, reconnect and then 'catch up' by continuing from
the recorded position.

Both the master and each slave must be configured with a unique id
(using the `server-id' option). In addition, the slave must be
configured with information about the master host name, log file name
and position within that file. These details can be controlled from
within a MySQL session using the `CHANGE MASTER' statement. The details
are stored within the `master.info' file.

In this section the setup and configuration required for a replication
environment is described, including step-by-step instructions for
creating a new replication environment. The major components of this
section are:

   * For a guide to setting up two or more servers for replication see
     *Note replication-howto::. This section deals with the setup of
     the systems and provides methods for copying data between the
     master and slaves.

   * Events in the binary log are recorded using a number of formats.
     These are referred to as statement based replication (SBR) or row
     based replication (RBR). A third type, mixed-format replication
     (MIXED), uses SBR or RBR replication automatically to take
     advantage of the benefits of both SBR and RBR formats when
     appropriate. The different formats are discussed in *Note
     replication-formats::.

   * Detailed information on the different configuration options and
     variables that apply to replication is provided in *Note
     replication-options::.

   * Once started, the replication process should require little
     administration or monitoring. However, for advice on common tasks
     that you may want to executed, see *Note
     replication-administration::.


File: manual.info,  Node: replication-howto,  Next: replication-formats,  Prev: replication-configuration,  Up: replication-configuration

19.1.1 How to Set Up Replication
--------------------------------

* Menu:

* replication-howto-repuser::    Creating a User for Replication
* replication-howto-masterbaseconfig::  Setting the Replication Master Configuration
* replication-howto-slavebaseconfig::  Setting the Replication Slave Configuration
* replication-howto-masterstatus::  Obtaining the Master Replication Information
* replication-howto-mysqldump::  Creating a Data Snapshot Using `mysqldump'
* replication-howto-rawdata::    Creating a Data Snapshot Using Raw Data Files
* replication-howto-newservers::  Setting Up Replication with New Master and Slaves
* replication-howto-existingdata::  Setting Up Replication with Existing Data
* replication-howto-additionalslaves::  Introducing Additional Slaves to an Existing Replication Environment
* replication-howto-slaveinit::  Setting the Master Configuration on the Slave

This section describes how to set up complete replication of a MySQL
server. There are a number of different methods for setting up
replication, and the exact method that you use will depend on how you
are setting up replication, and whether you already have data within
your master database.

There are some generic tasks which may be required for all replication
setups:

   * You may want to create a separate user that will be used by your
     slaves to authenticate with the master to read the binary log for
     replication. The step is optional. See *Note
     replication-howto-repuser::.

   * You must configure the master to support the binary log and
     configure a unique ID. See *Note
     replication-howto-masterbaseconfig::.

   * You must configure a unique ID for each slave that you want to
     connect to the Master. See *Note
     replication-howto-slavebaseconfig::.

   * Before starting a data snapshot or the replication process, you
     should record the position of the binary log on the master. You
     will need this information when configuring the slave so that the
     slave knows where within the binary log to start executing events.
     See *Note replication-howto-masterstatus::.

   * If you already have data on your Master and you want to
     synchronize your slave with this base data, then you will need to
     create a data snapshot of your database. You can create a snapshot
     using `mysqldump' (see *Note replication-howto-mysqldump::) or by
     copying the data files directly (see *Note
     replication-howto-rawdata::).

   * You will need to configure the slave with the Master settings,
     such as the hostname, login credentials and binary log name and
     positions. See *Note replication-howto-slaveinit::.

Once you have configured the basic options, you will need to follow the
instructions for your replication setup. A number of alternatives are
provided:

   * If you are setting up a new MySQL master and one or more slaves,
     then you need only set up the configuration, as you have no data
     to exchange. For guidance on setting up replication in this
     situation, see *Note replication-howto-newservers::.

   * If you are already running a MySQL server, and therefore already
     have data that will need to be transferred to your slaves before
     replication starts, have not previously configured the binary log
     and are able to shut down your MySQL server for a short period
     during the process, see *Note replication-howto-existingdata::.

   * If you are setting up additional slaves to an existing replication
     environment then you can set up the slaves without affecting the
     master. See *Note replication-howto-additionalslaves::.

If you want to administer a MySQL replication setup, we suggest that
you read this entire chapter through and try all statements mentioned
in *Note replication-master-sql::, and *Note replication-slave-sql::.
You should also familiarize yourself with the replication startup
options described in *Note replication-options::.

*Note*:

Note that certain steps within the setup process require the `SUPER'
privilege. If you do not have this privilege then enabling replication
may not be possible.


File: manual.info,  Node: replication-howto-repuser,  Next: replication-howto-masterbaseconfig,  Prev: replication-howto,  Up: replication-howto

19.1.1.1 Creating a User for Replication
........................................

Each Slave must connect to the Master using a standard username and
password. The user that you use for this operation can be any user,
providing they have been granted the `REPLICATION SLAVE' privilege.

You do not need to create a specific user for replication.  However,
you should be aware that the username and password will be stored in
plain text within the `master.info' file. Therefore you may want to
create a user that only has privileges for the replication process.

To create a user or grant an existing user the privileges required for
replication use the `GRANT' statement. If you create a user solely for
the purposes of replication then that user only needs the `REPLICATION
SLAVE' privilege. For example, to create a user, `repl', that allows
all hosts within the domain `mydomain.com' to connect for replication:

     mysql> GRANT REPLICATION SLAVE ON *.*
         -> TO 'repl'@'%.mydomain.com' IDENTIFIED BY 'slavepass';

See *Note grant::, for more information on the `GRANT' statement.

You may wish to create a different user for each slave, or use the same
user for each slave that needs to connect. As long as each user that
you want to use for the replication process has the `REPLICATION SLAVE'
privilege you can create as many users as you require.


File: manual.info,  Node: replication-howto-masterbaseconfig,  Next: replication-howto-slavebaseconfig,  Prev: replication-howto-repuser,  Up: replication-howto

19.1.1.2 Setting the Replication Master Configuration
.....................................................

For replication to work you _must_ enable binary logging on the master.
If binary logging is not enabled, replication will not be possible as
it is the binary log that is used to exchange data between the master
and slaves.

Each server within a replication group must have a unique `server-id'.
The server-id is used to identify individual servers within the group,
and must be positive integer between 1 and (2^32)-1). How you organize
and select the numbers is entirely up to you.

To configure both these options you will need to shut down your MySQL
server and edit the configuration of the `my.cnf' or `my.ini' file.

You will need to add the following options to the configuration file
within the `[mysqld]' section. If these options already exist, but are
commented out, uncomment the options and alter them according to your
needs. For example, to enable binary logging, using a log filename
prefix of mysql-bin, and setting a server ID of 1:

     [mysqld]
     log-bin=mysql-bin
     server-id=1

*Note*:

For the greatest possible durability and consistency in a replication
setup using `InnoDB' with transactions, you should use
`innodb_flush_log_at_trx_commit=1' and `sync_binlog=1' in the master
`my.cnf' file.

*Note*:

Ensure that the `skip-networking' option has not been enabled on your
replication master. If networking has been disabled, then your slave
will not able to communicate with the master and replication will fail.


File: manual.info,  Node: replication-howto-slavebaseconfig,  Next: replication-howto-masterstatus,  Prev: replication-howto-masterbaseconfig,  Up: replication-howto

19.1.1.3 Setting the Replication Slave Configuration
....................................................

The only option you must configure on the slave is to set the unique
server ID. If this option is not already set, or the current value
conflicts with the value that you have chosen for the master server,
then you should shut down your slave server, and edit the configuration
to specify the server id. For example:

     [mysqld]
     server-id=2

If you are setting up multiple slaves, each one must have a unique
`server-id' value that differs from that of the master and from each of
the other slaves. Think of `server-id' values as something similar to IP
addresses: These IDs uniquely identify each server instance in the
community of replication partners.

If you do not specify a `server-id' value, it is set to 1 if you have
not defined `master-host'; if you have set `master-host', then
`server-id' is set to 2.

*Note*:

If you omit `server-id', a master refuses connections from all slaves,
and a slave refuses to connect to a master. Thus, omitting `server-id'
is good only for backup with a binary log.

You do not have to enable binary logging on the slave for replication
to be enabled. However, if you enable binary logging on the slave then
you can use the binary log for data backups and crash recovery on the
slave, and also use the slave as part of a more complex replication
topology.


File: manual.info,  Node: replication-howto-masterstatus,  Next: replication-howto-mysqldump,  Prev: replication-howto-slavebaseconfig,  Up: replication-howto

19.1.1.4 Obtaining the Master Replication Information
.....................................................

To configure replication on the slave you must determine the masters
current point within the master binary log. You will need this
information so that when the slave starts the replication process, it
is able to start processing events from the binary log at the correct
point.

If you have existing data on your master that you want to synchronize
on your slaves before starting the replication process, then you must
stop processing statements on the master, obtain the current position,
and then dump the data, before allowing the master to continue
executing statements. If you do not stop the execution of statements
then the data dump, the master status information that you use will not
match and you will end up with inconsistent or corrupted databases on
the slaves.

To get the master status information, follow these steps:

  1. Start the command line client and flush all tables and block write
     statements by executing the `FLUSH TABLES WITH READ LOCK'
     statement:

          mysql> FLUSH TABLES WITH READ LOCK;

     For `InnoDB' tables, note that `FLUSH TABLES WITH READ LOCK' also
     blocks `COMMIT' operations.

     *Warning*:

     Leave the client from which you issued the `FLUSH TABLES'
     statement running so that the read lock remains in effect. If you
     exit the client, the lock is released.

  2. Use the `SHOW MASTER STATUS' statement to determine the current
     binary log name and offset on the master:

          mysql > SHOW MASTER STATUS;
          +---------------+----------+--------------+------------------+
          | File          | Position | Binlog_Do_DB | Binlog_Ignore_DB |
          +---------------+----------+--------------+------------------+
          | mysql-bin.003 | 73       | test         | manual,mysql     |
          +---------------+----------+--------------+------------------+

     The `File' column shows the name of the log and `Position' shows
     the offset within the file. In this example, the binary log file is
     `mysql-bin.003' and the offset is 73.  Record these values. You
     need them later when you are setting up the slave. They represent
     the replication coordinates at which the slave should begin
     processing new updates from the master.

     If the master has been running previously without binary logging
     enabled, the log name and position values displayed by `SHOW
     MASTER STATUS' or `mysqldump --master-data' will be empty. In that
     case, the values that you need to use later when specifying the
     slave's log file and position are the empty string (`''') and `4'.

You now have the information you need to enable the slave to start
reading from the binary log in the correct place to start replication.

If you have existing data that needs be to synchronized with the slave
before you start replication, leave the client running so that the lock
remains in place and then proceed to *Note
replication-howto-mysqldump::, or *Note replication-howto-rawdata::.

If you are setting up a brand new master and slave replication group,
then you can exit the client and release the locks.


File: manual.info,  Node: replication-howto-mysqldump,  Next: replication-howto-rawdata,  Prev: replication-howto-masterstatus,  Up: replication-howto

19.1.1.5 Creating a Data Snapshot Using `mysqldump'
...................................................

One way to create a snapshot of the data in an existing master database
is to use the `mysqldump' tool. Once the data dump has been completed,
you then import this data into the slave before starting the
replication process.

To obtain a snapshot of the data using `mysqldump':

   * If you haven't already locked the tables on the server to prevent
     queries that update data from executing:

     Start the command line client and flush all tables and block write
     statements by executing the `FLUSH TABLES WITH READ LOCK'
     statement:

          mysql> FLUSH TABLES WITH READ LOCK;

     Remember to use `SHOW MASTER STATUS' and record the binary log
     details for use when starting up the slave. The point in time of
     your snapshot and the binary log position must match. See *Note
     replication-howto-masterstatus::.

   * In another session, use `mysqldump' to create a dump either of all
     the databases you want to replicate, or by selecting specific
     databases individually.  For example:

          shell> mysqldump --all-databases --lock-all-tables >dbdump.db

   * An alternative to using a bare dump, is to use the `--master-data'
     option, which will automatically append the `CHANGE MASTER'
     statement required on the slave to start the replication process.

          shell> mysqldump --all-databases --master-data >dbdump.db

When choosing databases to include in the dump, remember that you will
need to filter out databases on each slave that you do not want to
include in the replication process.

You will need either to copy the dump file to the slave, or to use the
file from the master when connecting remotely to the slave to import
the data.


File: manual.info,  Node: replication-howto-rawdata,  Next: replication-howto-newservers,  Prev: replication-howto-mysqldump,  Up: replication-howto

19.1.1.6 Creating a Data Snapshot Using Raw Data Files
......................................................

If your database is particularly large then copying the raw data files
may be more efficient than using `mysqldump' and importing the file on
each slave.

However, using this method with tables in storage engines with complex
caching or logging algorithms may not give you a perfect `in time'
snapshot as cache information and logging updates may not have been
applied, even if you have acquired a global read lock. How the storage
engine responds to this depends on its crash recovery abilities.

For example, if you are using `InnoDB' tables, you should use the
``InnoDB' Hot Backup' tool to obtain a consistent snapshot. This tool
records the log name and offset corresponding to the snapshot to be
later used on the slave. `Hot Backup' is a non-free (commercial) tool
that is not included in the standard MySQL distribution. See the
``InnoDB' Hot Backup' home page at `http://www.innodb.com/hot-backup'
for detailed information.

Otherwise, you can obtain a reliable binary snapshot of `InnoDB' tables
only after shutting down the MySQL Server.

To create a raw data snapshot of `MyISAM' tables you can use standard
copy tools such as `cp' or `copy', a remote copy tool such as `scp' or
`rsync' an archiving tool such as `zip' or `tar', or a file system
snapshot tool such as `dump', providing that your MySQL data files
exist on a single filesystem. If you are only replicating certain
databases then make sure you only copy those files that related to
those tables. (For `InnoDB', all tables in all databases are stored in
a single file unless you have the `innodb_file_per_table' option
enabled.)

You may want to specifically exclude the following files from your
archive:

   * Files relating to the `mysql' database.

   * The `master.info' file.

   * The master's binary log files.

   * Any relay log files.

To get the most consistent results with a raw data snapshot you should
shut down the server during the process, as below:

  1. Acquire a read lock and get the master's status. See *Note
     replication-howto-masterstatus::.

  2. In a separate session, shut down the MySQL server:

          shell> mysqladmin shutdown

  3. Make a copy of the MySQL data files. Examples are shown below for
     common ways to do this - you need to choose only one of them:

          shell> tar cf /TMP/DB.TAR ./DATA
          shell> zip -r /TMP/DB.ZIP ./DATA
          shell> rsync --recursive ./DATA /TMP/DBDATA

  4. Start up the MySQL instance on the master.

If you are not using `InnoDB' tables, you can get a snapshot of the
system from a master without shutting down the server as described in
the following steps:

  1. Acquire a read lock and get the master's status. See *Note
     replication-howto-masterstatus::.

  2. Take a copy of the MySQL data files. Examples are shown below for
     common solutions - you need to choose only one of these solutions:

          shell> tar cf /TMP/DB.TAR ./DATA
          shell> zip -r /TMP/DB.ZIP ./DATA
          shell> rsync --recursive ./DATA /TMP/DBDATA

  3. In the client where you acquired the read lock, free the lock:

          mysql> UNLOCK TABLES;

Once you have created the archive or copy of the database, you will
need to copy the files to each slave before starting the slave
replication process.


File: manual.info,  Node: replication-howto-newservers,  Next: replication-howto-existingdata,  Prev: replication-howto-rawdata,  Up: replication-howto

19.1.1.7 Setting Up Replication with New Master and Slaves
..........................................................

Setting up replication with a new Master and Slaves (i.e. with no
existing data) is the easiest and most straightforward method for
setting up replication.

You can also use this method if you are setting up new servers and have
an existing dump of the databases that you want to load into your
replication configuration. By loading the data onto a new master, the
data will be automatically replicated to the slaves.

To set up replication between a new master and slave:

  1. Configure the MySQL master with the necessary configuration
     properties. See *Note replication-howto-masterbaseconfig::.

  2. Start up the MySQL master.

  3. Setup a user, see *Note replication-howto-repuser::.

  4. Obtain the master status information. See *Note
     replication-howto-masterstatus::.

  5. Free the read lock:

          mysql> UNLOCK TABLES;

  6. On the slave, edit the MySQL configuration. See *Note
     replication-howto-slavebaseconfig::.

  7. Start up the MySQL slave.

  8. Execute the `CHANGE MASTER' command to set the master replication
     server configuration.

Because there is no data to load or exchange on a new server
configuration you do not need to copy or import any information.

If you are setting up a new replication environment using the data from
an existing database server, you will now need to run the dump file on
the master. The database updates will automatically be propagated to
the slaves:

     shell> mysql -h master < fulldb.dump


File: manual.info,  Node: replication-howto-existingdata,  Next: replication-howto-additionalslaves,  Prev: replication-howto-newservers,  Up: replication-howto

19.1.1.8 Setting Up Replication with Existing Data
..................................................

When setting up replication with existing data, you will need to decide
how best to get the data from the master to the slave before starting
the replication service.

The basic process for setting up replication with existing data is as
follows:

  1. If you have not already configured the `server-id' and binary
     logging, you will need to shut down your master to configure these
     options. See *Note replication-howto-masterbaseconfig::.

     If you have to shut down your master database, then this is a good
     opportunity to take a snapshot of the database. You should obtain
     the master status (see *Note replication-howto-masterstatus::)
     before taking the database down, updating the configuration and
     taking a snapshot. For information on how to create a snapshot
     using raw data files, see *Note replication-howto-rawdata::.

  2. If your server is already correctly configured, obtain the master
     status (see *Note replication-howto-masterstatus::) and then use
     `mysqldump' to take a snapshot (see *Note
     replication-howto-mysqldump::) or take a raw snapshot of the live
     database using the guide in *Note replication-howto-rawdata::.

  3. With the MySQL master running, create a user to be used by the
     slave when connecting to the master during replication.  See *Note
     replication-howto-repuser::.

  4. Update the configuration of the slave, see *Note
     replication-howto-slavebaseconfig::.

  5. The next step depends on how you created the snapshot of data on
     the master.

     If you used `mysqldump':

       1. Startup the slave, skipping replication by using the
          `--skip-slave' option.

       2. Import the dump file:

               shell> mysql < fulldb.dump

     If you created a snapshot using the raw data files:

       1. Extract the data files into your slave data directory.  For
          example:

               shell> tar xvf dbdump.tar

          You may need to set permissions and ownership on the files to
          match the configuration of your slave.

       2. Startup the slave, skipping replication by using the
          `--skip-slave' option.

  6. Configure the slave with the master status information. This will
     tell the slave the binary log file and position within the file
     where replication needs to start, and configure the login
     credentials and hostname of the master. For more information on
     the statement required, see *Note replication-howto-slaveinit::.

  7. Start the slave threads:

          mysql> START SLAVE;

After you have performed this procedure, the slave should connect to
the master and catch up on any updates that have occurred since the
snapshot was taken.

If you have forgotten to set the `server-id' option for the master,
slaves cannot connect to it.

If you have forgotten to set the `server-id' option for the slave, you
get the following error in the slave's error log:

     Warning: You should set server-id to a non-0 value if master_host
     is set; we will force server id to 2, but this MySQL server will
     not act as a slave.

You also find error messages in the slave's error log if it is not able
to replicate for any other reason.

Once a slave is replicating, you can find in its data directory one
file named `master.info' and another named `relay-log.info'. The slave
uses these two files to keep track of how much of the master's binary
log it has processed. Do _not_ remove or edit these files unless you
know exactly what you are doing and fully understand the implications.
Even in that case, it is preferred that you use the `CHANGE MASTER TO'
statement to change replication parameters. The slave will use the
values specified in the statement to update the status files
automatically.

*Note*:

The content of `master.info' overrides some of the server options
specified on the command line or in `my.cnf'. See *Note
replication-options::, for more details.

Once you have a snapshot of the master, you can use it to set up other
slaves by following the slave portion of the procedure just described.
You do not need to take another snapshot of the master; you can use the
same one for each slave.


File: manual.info,  Node: replication-howto-additionalslaves,  Next: replication-howto-slaveinit,  Prev: replication-howto-existingdata,  Up: replication-howto

19.1.1.9 Introducing Additional Slaves to an Existing Replication Environment
.............................................................................

If you want to add another slave to the existing replication
configuration then you can do so without stopping the master.  Instead,
you duplicate the settings on the slaves.

To duplicate the slave:

  1. Shut down the existing slave:

          shell> mysqladmin shutdown

  2. Copy the data directory from the existing slave to the new slave.
     You can do this by creating an archive using `tar' or `WinZip', or
     by performing a direct copy using a tool such as `cp' or `rsync'.
     Ensure you also copy the log files and relay log files.

     *Note*:

     A common problem that is encountered when adding new replication
     slaves is that the new slave fails with a series of warning and
     error messages like these:

          071118 16:44:10 [Warning] Neither --relay-log nor --relay-log-index were used; so
          replication may break when this MySQL server acts as a slave and has his hostname
          changed!! Please use '--relay-log=NEW_SLAVE_HOSTNAME-relay-bin' to avoid this problem.
          `071118 16:44:10 [ERROR] Failed to open the relay log './OLD_SLAVE_HOSTNAME-relay-bin.003525'
          (relay_log_pos 22940879)'
          071118 16:44:10 `[ERROR] Could not find target log during relay log initialization'
          071118 16:44:10 `[ERROR] Failed to initialize the master info structure'

     This is due to the fact that, if the `--relay-log' option is not
     specified, the relay log files contain the hostname as part of
     their filenames. (This is also true of the relay log index file if
     the `--relay-log-index' option is not used. See *Note
     replication-options::, for more information about these options.)

     To avoid this problem, use the same value for `--relay-log' on the
     new slave that was used on the existing slave. (If this option was
     not set explicitly on the existing slave, use
     `EXISTING_SLAVE_HOSTNAME-relay-bin'.)  If this is not feasible,
     then copy the existing slave's relay log index file to the new
     slave and set the `--relay-log-index' option on the new slave to
     match what was used on the existing slave. (If this option was not
     set explicitly on the existing slave, use
     `EXISTING_SLAVE_HOSTNAME-relay-bin.index'.)  Alternatively -- if
     you have already tried to start the new slave (after following the
     remaining steps in this section) and have encountered errors like
     those described previously -- then perform the following steps:

       1. If you have not already done so, issue a `STOP SLAVE' on the
          new slave.

          If you have already started the existing slave again, issue a
          `STOP SLAVE' on the existing slave as well.

       2. Copy the contents of the existing slave's relay log index
          file into the the new slave's relay log index file, making
          sure to overwrite any content already in the file.

       3. Proceed with the remaining steps in this section.

  3. Copy the `master.info' and `relay.info' files from the existing
     slave to the new slave. These files hold the current log positions.

  4. Start the existing slave.

  5. On the new slave, edit the configuration and the give the new
     slave a new unique `server-id'.

  6. Start the new slave; the `master.info' file options will be used
     to start the replication process.


File: manual.info,  Node: replication-howto-slaveinit,  Prev: replication-howto-additionalslaves,  Up: replication-howto

19.1.1.10 Setting the Master Configuration on the Slave
.......................................................

To set up the slave to communicate with the master for replication, you
must tell the slave the necessary connection information. To do this,
execute the following statement on the slave, replacing the option
values with the actual values relevant to your system:

     mysql> CHANGE MASTER TO
         ->     MASTER_HOST='MASTER_HOST_NAME',
         ->     MASTER_USER='REPLICATION_USER_NAME',
         ->     MASTER_PASSWORD='REPLICATION_PASSWORD',
         ->     MASTER_LOG_FILE='RECORDED_LOG_FILE_NAME',
         ->     MASTER_LOG_POS=RECORDED_LOG_POSITION;

*Note*:

Replication cannot use Unix socket files. You must be able to connect
to the master MySQL server using TCP/IP.

The following table shows the maximum allowable length for the
string-valued options:

`MASTER_HOST'  60
`MASTER_USER'  16
`MASTER_PASSWORD'32
`MASTER_LOG_FILE'255


File: manual.info,  Node: replication-formats,  Next: replication-options,  Prev: replication-howto,  Up: replication-configuration

19.1.2 Replication Formats
--------------------------

* Menu:

* replication-sbr-rbr::          Comparison of Statement-Based and Row-Based Replication
* replication-rbr-usage::        Usage of Row-based Logging and Row-Based Replication

Replication works because events written to the binary log are read
from the master and then processed on the slave. The events are
recorded within the binary log in different formats according the type
of event being recorded. The different replication formats used
correspond to the binary logging format used when the events were
recorded in the master's binary log. The correlation between binary
logging formats and the terms used during replication are:

   * Replication capabilities in MySQL originally were based on
     propagation of SQL statements from master to slave. This is called
     _statement-based replication_ (often abbreviated as _SBR_), which
     corresponds to the standard statement-based binary logging format.
     In MySQL 5.1.4 and earlier, binary logging and replication used
     this format exclusively.

   * Row-based binary logging logs changes in individual table rows.
     When used with MySQL replication, this is known as _row-based
     replication_ (often abbreviated as _RBR_). In row-based
     replication, the master writes messages known as _events_ to the
     binary log that indicate how individual table rows are changed.

   * As of MySQL 5.1.8, the binary logging format can be changed in
     real time according to the event being logged when using
     mixed-format logging. When the mixed format is in effect,
     statement-based logging is used by default, but automatically
     switches to row-based logging in particular cases as described
     below. This is sometimes referred to as _mixed-based replication_
     (abbreviated as _MBR_). For more information, see *Note
     binary-log-mixed::.

Starting with MySQL 5.1.12, the mixed format is the default for MySQL
replication.

Starting with MySQL 5.1.20, the binary logging format is determined in
part by the storage engine being used and the statement being executed.
For more information on mixed-format logging and the rules governing
the support of different logging formats, see *Note binary-log-mixed::.

The statement-based and row-based replication formats have different
issues and limitations. For a comparison of their relative advantages
and disadvantages, see *Note replication-sbr-rbr::.

*Note*:

MySQL Cluster Replication always uses row-based replication, and the
`NDBCLUSTER' storage engine is incompatible with statement-based
replication. Using `NDBCLUSTER' sets row-based logging format
automatically. For more information, see *Note
mysql-cluster-replication::.

With statement-based replication, you may encounter issues with
replicating stored routines or triggers. You can avoid these issues by
using row-based replication instead. For more information, see *Note
stored-procedure-logging::.

If you build MySQL from source, row-based replication is available by
default unless you invoke `configure' with the
`--without-row-based-replication' option.

For MySQL 5.1.20 and later (and MySQL 5.0.46 for backwards
compatibility), the following session variables are written to the
binary log and honoured by the replication slave when parsing the
binary log:

   * `SQL_MODE'

   * `FOREIGN_KEY_CHECKS'

   * `UNIQUE_CHECKS'

   * `CHARACTER_SET_CLIENT'

   * `COLLATION_CONNECTION'

   * `COLLATION_DATABASE'

   * `COLLATION_SERVER'

   * `SQL_AUTO_IS_NULL'

*Important*:

Even though session variables relating to character sets and collations
are written to the binary log, replication between different character
sets is not supported.


File: manual.info,  Node: replication-sbr-rbr,  Next: replication-rbr-usage,  Prev: replication-formats,  Up: replication-formats

19.1.2.1 Comparison of Statement-Based and Row-Based Replication
................................................................

Each binary logging format has advantages and disadvantages. For most
users, the mixed replication format should provide the best combination
of data integrity and performance. If, however, you want to take
advantage of the features specific to the statement-based or row-based
replication format when performing certain tasks, then you can use the
information in this section, which provides a summary of their relative
advantages and disadvantages, to determine which is best for your needs.

*Advantages of statement-based replication:*

   * Proven technology that has existed in MySQL since 3.23.

   * Smaller log files. When updates or deletes affect many rows,
     _much_ smaller log files. Smaller log files require less storage
     space and are faster to back up.

   * Log files contain all statements that made any changes, so they
     can be used to audit the database.

   * Log files can be used for point-in-time recovery, not just for
     replication purposes. See *Note point-in-time-recovery::.

   * You can use a slave with a higher version than that used on the
     master, even when there is a different row structure in the table.
     This can be useful if you are unable to upgrade the master but
     want to take advantage of features in a recent slave version,
     perhaps for testing and evaluation purposes.

*Disadvantages of statement-based replication:*

   * Not all `UPDATE' statements can be replicated: Any
     non-deterministic behavior (for example, when using random
     functions in an SQL statement) is hard to replicate when using
     statement-based replication. For statements that use a
     non-deterministic user-defined function (UDF), it is not possible
     to replicate the result using statement-based replication, whereas
     row-based replication will just replicate the value returned by the
     UDF.

   * Statements cannot be replicated properly if they use a UDF that is
     non-deterministic (its value depends on other factors than the
     given parameters).

   * Statements that use one of the following functions cannot be
     replicated properly:

        * `LOAD_FILE()'

        * `UUID()', `UUID_SHORT()'

        * `USER()'

        * `FOUND_ROWS()'

        * `SYSDATE()' (unless the server is started with the
          `--sysdate-is-now' option)

     All other functions are replicated correctly (including `RAND()',
     `NOW()', `LOAD DATA INFILE', and so forth).

   * `INSERT ... SELECT' requires a greater number of row-level locks
     than with row-based replication.

   * `UPDATE' statements that require a table scan (because no index is
     used in the `WHERE' clause) must lock a greater number of rows
     than with row-based replication.

   * For `InnoDB': An `INSERT' statement that uses `AUTO_INCREMENT'
     blocks other non-conflicting `INSERT' statements.

   * For complex queries, the statement must be evaluated and executed
     on the slave before the rows are updated or inserted. With
     row-based replication, the slave only has to run the statement to
     apply the differences, not the full query.

   * Stored functions (not stored procedures) will execute with the
     same `NOW()' value as the calling statement. (This may be regarded
     both as a bad thing and a good thing.)

   * Deterministic UDFs must be applied on the slaves.

   * If there is an error in evaluation on the slave, particularly when
     executing complex queries, then using statement based replication
     may slowly increase the margin of error across the affected rows
     over time.

   * Tables have to be (almost) identical on master and slave.

* Advantages of row-based replication:*

   * All changes can be replicated. This is the safest form of
     replication.

     For MySQL versions earlier than 5.1.14, DDL (data definition
     language) statements such as `CREATE TABLE' are replicated using
     statement-based replication, while DML (data manipulation
     language) statements, as well as `GRANT' and `REVOKE' statements,
     are replicated using row-based-replication.

     In MySQL 5.1.14 and later, the `mysql' database is not replicated.
     The `mysql' database is instead seen as a node-specific database.
     Row-based replication is not supported on tables in this database.
     Instead, statements that would normally update this information --
     such as `GRANT', `REVOKE' and the manipulation of triggers, stored
     routines (including stored procedures), and views -- are all
     replicated to slaves using statement-based replication.

     For statements like `CREATE ... SELECT', a `CREATE' statement is
     generated from the table definition and replicated using the
     statement-based format, while the row insertions are replicated
     using the row-based format.

   * The technology is the same as in most other database management
     systems; knowledge about other systems transfers to MySQL.

   * In many cases, it is faster to apply data on the slave for tables
     that have primary keys.

   * Fewer locks needed (and thus higher concurrency) on the master for
     the following types of statements:

        * `INSERT ... SELECT'

        * `INSERT' statements with `AUTO_INCREMENT'

        * `UPDATE' or `DELETE' statements with `WHERE' clauses that
          don't use keys or don't change most of the examined rows.

   * Fewer locks on the slave for any `INSERT', `UPDATE', or `DELETE'
     statement.

   * It's possible to add multiple threads to apply data on the slave
     in the future (works better on SMP machines).

*Disadvantages of row-based replication:*

   * Larger log files (much larger in some cases).

   * Binary log will contain data for large statements that were rolled
     back.

   * When using row-based replication to replicate a statement (for
     example, an `UPDATE' or `DELETE' statement), each changed row must
     be written to the binary log. In contrast, when using
     statement-based replication, only the statement is written to the
     binary log. If the statement changes many rows, row-based
     replication may write significantly more data to the binary log.
     In these cases the binary log will be locked for a longer time to
     write the data, which may cause concurrency problems.

   * Deterministic UDFs that generate large `BLOB' values will be
     notably slower to replicate.

   * You cannot examine the logs to see what statements were executed.

   * You cannot see on the slave what statements were received from the
     master and executed.

   * When making a bulk operation that includes non-transactional
     storage engines, changes are applied as the statement executes.
     With row-based replication logging, this means that the binary log
     is written while the statement is running. On the master, this
     doesn't provide any problems with concurrency, because tables are
     locked until the bulk operation terminates. On the slave server,
     however, tables aren't locked while the slave applies changes,
     because it doesn't know that those changes are part of a bulk
     operation.

     In that scenario, if you retrieve data from a table on the master
     (for example, `SELECT * FROM table_name'), the server will wait
     for the bulk operation to complete before executing the `SELECT'
     statement, because the table is read-locked. On the slave, the
     server won't wait (because there is no lock). This means that
     until the `bulk operation' on the slave has completed you will get
     different results for the same `SELECT' query on the master and on
     the slave.

     This behavior will eventually change, but until it does, you
     should probably use statement-based replication in a scenario like
     this.


File: manual.info,  Node: replication-rbr-usage,  Prev: replication-sbr-rbr,  Up: replication-formats

19.1.2.2 Usage of Row-based Logging and Row-Based Replication
.............................................................

Using row-based logging or replication, rather than statement-based
logging or replication, can result in major changes in the replication
environment and in the behavior of applications. This section describes
a number of issues and limitations known to exist when using row-based
logging or row-based replication. In addition, this section also
discusses some best practices for taking advantage of row-based logging
(RBL) and row-based replication (RBR).

For additional information, see *Note replication-sbr-rbr::, and *Note
replication-formats::.

   * RBL, RBR, and temporary tables

     As noted elsewhere in this chapter (see *Note
     replication-features-temptables::), temporary tables are not
     replicated when using the row-based format. However, you can use
     the mixed format; when mixed format is in effect, `safe'
     statements involving temporary tables are logged using the
     statement-based format. For more information, see *Note
     replication-sbr-rbr::.

   * RBL and the `BLACKHOLE' storage engine

     While it is possible to use the `BLACKHOLE' storage engine in
     combination with RBL or RBR, you should be aware of the following
     issues:

        * `DELETE' and `UPDATE' statements currently do not work with
          RBL. This is a known issue which we are working to correct in
          a future MySQL release (see Bug#38360
          (http://bugs.mysql.com/38360)).

        * DDL statements are not supported on `BLACKHOLE' tables when
          using RBL.  This is by design.

   * RBL and synchronization of non-transactional tables

     When executing a statement on the master that would update
     multiple rows, the table is locked on the master while all the
     affected rows are updated. When using non-transactional storage
     engines, including `MyISAM', the changes to each row are written
     to the binary log as each row is modified. On the slave, each RBL
     statement is executed individually, without the table lock that
     would have been in place on the master for the duration of the
     original statement, because it cannot determine that the
     individual row updates were part of a bulk statement. This can
     cause synchronization problems, since `SELECT' statements issued
     on the master and on a slave may return different data for
     individual rows during the execution of the original statement.

   * Latency and binary log size

     Because RBL writes changes for each row to the binary log, the
     size of the binary log can grow quite rapidly. When used in a
     replication environment, this can significantly increase the time
     required for making the changes on the slave that match those on
     the master. You should be aware of the potential for this delay in
     your applications.

   * Reading and recovering from the binary log

     The `mysqlbinlog' tool is currently not able to format the
     contents of the binary log in a manner that is easily
     human-readable. This can cause problems if you want to read or
     recover from a replication or database failure using the contents
     of the binary log. We are working to overcome this limitation of
     `mysqlbinlog' in a future MySQL release; for more information, see
     Bug#31455 (http://bugs.mysql.com/31455).

     In addition, there is no direct relationship between logged
     changes and the original SQL statement or statements that
     generated these changes. This makes it difficult to identify a
     problem statement or perform point-in-time recovery based on the
     statements that made the changes.

   * Binary log execution errors and `slave_exec_mode'

     If you use `slave_exec_mode=IDEMPOTENT', a failure to apply
     changes from RBL because the original row cannot be found does not
     trigger an error, and does not cause replication to fail. This
     means that it is possible that updates are not applied on the
     slave, so that the master and slave are no longer synchronized.
     Latency issues and use of non-transactional tables when using
     `slave_exec_mode=IDEMPOTENT' and RBR can cause the master and
     slave to diverge even further. For more information about
     `slave_exec_mode', see *Note server-system-variables::.

     *Note*:

     `slave_exec_mode=IDEMPOTENT' is generally useful only for circular
     replication or multi-master replication with MySQL Cluster. For
     other scenarios, the default value (`slave_exec_mode=STRICT') is
     normally sufficient.

   * Lack of binary log checksums

     No checksums are used for RBL. This means that network, disk, and
     other errors may not be identified when processing the binary log.
     To ensure that data is transmitted without network corruption, you
     may want to consider using SSL, which adds another layer of
     checksumming, for replication connections. See *Note
     secure-connections::, for more information about setting up MySQL
     with SSL.

   * Filtering based on server ID not supported

     A common practice is to filter out changes on some slaves by using
     a `WHERE' clause that includes the relation `@server_id <>
     SERVER-ID' clause with `UPDATE' and DELETE statements, a simple
     example of such a clause being `WHERE @server_id <> 1'. This does
     not work correctly with RBL. If you must use the `server_id'
     system variable for statement filtering, then you should use
     `--row-format=STATEMENT' or `--row-format=MIXED'. For more
     information about `server_id', see *Note server-system-variables::.

   * Database-level replication options

     The effects of the options `--replicate-do-db',
     `--replicate-ignore-db', and `--replicate-rewrite-db' differ
     considerably depending on whether row-based or statement-based
     logging is in use. Because of this, we recommend that you avoid
     the database-level options and use the table-level options such as
     `--replicate-do-table' and `--replicate-ignore-table' instead. For
     more information about these options and the impact that your
     choice of replication format has on how they operate, see *Note
     replication-options::.

   * `MyISAM' performance and RBL

     When using row-based logging, changes to rows are written to disk
     as soon as they are applied on the slave. When performing an
     update on `MyISAM' tables, the slave writes each row change
     separately to disk. This means that an `UPDATE' statement that
     affects many `MyISAM' tables may take longer to be applied on the
     slave when using row-based logging than when using statement-based
     logging.


File: manual.info,  Node: replication-options,  Next: replication-administration,  Prev: replication-formats,  Up: replication-configuration

19.1.3 Replication Options and Variables
----------------------------------------

This section describes the options that you can use on slave
replication servers. You can specify these options either on the
command line or in an option file.

On the master and each slave, you must use the `server-id' option to
establish a unique replication ID. For each server, you should pick a
unique positive integer in the range from 1 to 2^32 - 1, and each ID
must be different from every other ID.  Example: `server-id=3'

Options that you can use on the master server for controlling binary
logging are described in *Note binary-log::.

*Important*:

Certain options are handled in a special way in order to ensure that
the active replication configuration is not inadvertently altered or
affected:

   * In MySQL 5.1.16 and earlier, these options are ignored if the
     `master.info' file exists (i.e.  when the MySQL server has already
     previously been configured for replication). If the file exists
     and these options are present in the `my.cnf' or as options on the
     command line to `mysqld', they are silently ignored and the
     information in `master.info' used instead.

   * _Beginning with MySQL 5.1.17, these options are deprecated.
     Beginning with MySQL 5.2.5, they have been removed._ In MySQL
     5.1.17 and later versions of MySQL 5.1, these options have no
     effect when `mysqld' is started and an appropriate warning is
     written to the error log. To set the replication parameters
     associated with these you must use the `CHANGE MASTER TO ...'
     statement (see *Note change-master-to::).

The options affected are shown in this list:

   * `--master-host'

   * `--master-user'

   * `--master-password'

   * `--master-port'

   * `--master-connect-retry'

   * `--master-ssl'

   * `--master-ssl-ca'

   * `--master-ssl-capath'

   * `--master-ssl-cert'

   * `--master-ssl-cipher'

   * `--master-ssl-key'

The `master.info' file format in MySQL 5.1 includes values
corresponding to the SSL options.  In addition, the file format
includes as its first line the number of lines in the file. (See *Note
slave-logs::.) If you upgrade an older server (before MySQL 4.1.1) to a
newer version, the new server upgrades the `master.info' file to the
new format automatically when it starts. However, if you downgrade a
newer server to an older version, you should remove the first line
manually before starting the older server for the first time.

If no `master.info' file exists when the slave server starts, it uses
the values for those options that are specified in option files or on
the command line. This occurs when you start the server as a
replication slave for the very first time, or when you have run `RESET
SLAVE' and then have shut down and restarted the slave.

If the `master.info' file exists when the slave server starts, the
server uses its contents and ignores any options that correspond to the
values listed in the file. Thus, if you start the slave server with
different values of the startup options that correspond to values in the
`master.info' file, the different values have no effect, because the
server continues to use the `master.info' file. To use different values,
you must either restart after removing the `master.info' file or
(preferably) use the `CHANGE MASTER TO' statement to reset the values
while the slave is running.

Suppose that you specify this option in your `my.cnf' file:

     [mysqld]
     master-host=SOME_HOST

The first time you start the server as a replication slave, it reads
and uses that option from the `my.cnf' file. The server then records
the value in the `master.info' file. The next time you start the
server, it reads the master host value from the `master.info' file only
and ignores the value in the option file. If you modify the `my.cnf'
file to specify a different master host of SOME_OTHER_HOST, the change
still has no effect. You should use `CHANGE MASTER TO' instead.

This example shows a more extensive use of startup options to configure
a slave server:

     [mysqld]
     server-id=2
     master-host=db-master.mycompany.com
     master-port=3306
     master-user=pertinax
     master-password=freitag
     master-connect-retry=60
     report-host=db-slave.mycompany.com

*Note*:

Because the server gives an existing `master.info' file precedence over
the startup options just described, you might prefer not to use startup
options for these values at all, and instead to specify them by using
the `CHANGE MASTER TO' statement.  See *Note change-master-to::.

The following list describes the options and variables used for
controlling replication. Many of these options can be reset while the
server is running by using the `CHANGE MASTER TO' statement. Others,
such as the `--replicate-*' options, can be set only when the slave
server starts.

   *  `--log-slave-updates'

     Normally, a slave does not log to its own binary log any updates
     that are received from a master server. This option tells the
     slave to log the updates performed by its SQL thread to its own
     binary log. For this option to have any effect, the slave must
     also be started with the `--log-bin' option to enable binary
     logging.  `--log-slave-updates' is used when you want to chain
     replication servers. For example, you might want to set up
     replication servers using this arrangement:

          A -> B -> C

     Here, `A' serves as the master for the slave `B', and `B' serves
     as the master for the slave `C'. For this to work, `B' must be
     both a master _and_ a slave. You must start both `A' and `B' with
     `--log-bin' to enable binary logging, and `B' with the
     `--log-slave-updates' option so that updates received from `A' are
     logged by `B' to its binary log.

   *  `--log-warnings[=LEVEL]'

     This option causes a server to print more messages to the error
     log about what it is doing. With respect to replication, the
     server generates warnings that it succeeded in reconnecting after
     a network/connection failure, and informs you as to how each slave
     thread started. This option is enabled by default; to disable it,
     use `--skip-log-warnings'. Aborted connections are not logged to
     the error log unless the value is greater than 1.

   *  `--master-connect-retry=SECONDS'

     The number of seconds that the slave thread sleeps before trying
     to reconnect to the master in case the master goes down or the
     connection is lost. The value in the `master.info' file takes
     precedence if it can be read. If not set, the default is 60.
     Connection retries are not invoked until the slave times out
     reading data from the master according to the value of
     `--slave-net-timeout'. The number of reconnection attempts is
     limited by the `--master-retry-count' option.

     This option is deprecated as of MySQL 5.1.17, and removed in MySQL
     5.2.5 and later.

   *  `--master-host=HOST_NAME'

     The hostname or IP number of the master replication server.  The
     value in `master.info' takes precedence if it can be read. If no
     master host is specified, the slave thread does not start.

     This option is deprecated as of MySQL 5.1.17, and removed in MySQL
     5.2.5 and later.

   *  `--master-info-file=FILE_NAME'

     The name to use for the file in which the slave records
     information about the master. The default name is `master.info' in
     the data directory.

   *  `--master-password=PASSWORD'

     The password of the account that the slave thread uses for
     authentication when it connects to the master. The value in the
     `master.info' file takes precedence if it can be read. If not set,
     an empty password is assumed.

     This option is deprecated as of MySQL 5.1.17, and removed in MySQL
     5.2.5 and later.

   *  `--master-port=PORT_NUMBER'

     The TCP/IP port number that the master is listening on. The value
     in the `master.info' file takes precedence if it can be read. If
     not set, the compiled-in setting is assumed (normally 3306).

     This option is deprecated as of MySQL 5.1.17, and removed in MySQL
     5.2.5 and later.

   *  `--master-retry-count=COUNT'

     The number of times that the slave tries to connect to the master
     before giving up. Reconnects are attempted at intervals set by
     `--master-connect-retry' and reconnects are triggered when data
     reads by the slave time out according to the `--slave-net-timeout'
     option. The default value is 86400.

     *Note*:

     The `mysqld' option `--master-connect-retry' is deprecated as of
     MySQL 5.1.17, and removed in MySQL 5.2.5 and later. You should use
     the `MASTER_CONNECT_RETRY' option for the `CHANGE MASTER TO'
     statement instead.

   *  `--master-ssl', `--master-ssl-ca=FILE_NAME',
     `--master-ssl-capath=DIRECTORY_NAME',
     `--master-ssl-cert=FILE_NAME', `--master-ssl-cipher=CIPHER_LIST',
     `--master-ssl-key=FILE_NAME'

     These options are used for setting up a secure replication
     connection to the master server using SSL. Their meanings are the
     same as the corresponding `--ssl', `--ssl-ca', `--ssl-capath',
     `--ssl-cert', `--ssl-cipher', `--ssl-key' options that are
     described in *Note ssl-options::. The values in the `master.info'
     file take precedence if they can be read.

     These options are deprecated as of MySQL 5.1.17, and removed in
     MySQL 5.2.5 and later.

   *  `--master-user=USER_NAME'

     The username of the account that the slave thread uses for
     authentication when it connects to the master. This account must
     have the `REPLICATION SLAVE' privilege.  The value in the
     `master.info' file takes precedence if it can be read. If the
     master username is not set, the name `test' is assumed.

     This option is deprecated as of MySQL 5.1.17, and removed in MySQL
     5.2.5 and later.

   *  `--max-relay-log-size=SIZE'

     The size at which the server rotates relay log files
     automatically. For more information, see *Note slave-logs::. The
     default size is 1GB.

   *  `--read-only'

     Cause the slave to allow no updates except from slave threads or
     from users having the `SUPER' privilege.  This enables you to
     ensure that a slave server accepts no updates from clients. This
     option does not apply to `TEMPORARY' tables.

   *  `--relay-log=FILE_NAME'

     The basename for the relay log. The default basename is
     `HOST_NAME-relay-bin'.  The server creates relay log files in
     sequence by adding a numeric suffix to the basename. You can
     specify the option to create hostname-independent relay log names,
     or if your relay logs tend to be big (and you don't want to
     decrease `max_relay_log_size') and you need to put them in some
     area different from the data directory, or if you want to increase
     speed by balancing load between disks.

   *  `--relay-log-index=FILE_NAME'

     The name to use for the relay log index file. The default name is
     `HOST_NAME-relay-bin.index' in the data directory, where HOST_NAME
     is the name of the slave server.

   *  `--relay-log-info-file=FILE_NAME'

     The name to use for the file in which the slave records
     information about the relay logs. The default name is
     `relay-log.info' in the data directory.

   *  `--relay-log-purge={0|1}'

     Disable or enable automatic purging of relay logs as soon as they
     are no longer needed. The default value is 1 (enabled).  This is a
     global variable that can be changed dynamically with `SET GLOBAL
     relay_log_purge = N'.

   *  `--relay-log-space-limit=SIZE'

     This option places an upper limit on the total size in bytes of
     all relay logs on the slave. A value of 0 means `no limit.' This
     is useful for a slave server host that has limited disk space.
     When the limit is reached, the I/O thread stops reading binary log
     events from the master server until the SQL thread has caught up
     and deleted some unused relay logs. Note that this limit is not
     absolute: There are cases where the SQL thread needs more events
     before it can delete relay logs. In that case, the I/O thread
     exceeds the limit until it becomes possible for the SQL thread to
     delete some relay logs, because not doing so would cause a
     deadlock. You should not set `--relay-log-space-limit' to less
     than twice the value of `--max-relay-log-size' (or
     `--max-binlog-size' if `--max-relay-log-size' is 0). In that case,
     there is a chance that the I/O thread waits for free space because
     `--relay-log-space-limit' is exceeded, but the SQL thread has no
     relay log to purge and is unable to satisfy the I/O thread. This
     forces the I/O thread to temporarily ignore
     `--relay-log-space-limit'.

   *  `--replicate-do-db=DB_NAME'

     The effects of this option depend on whether statement-based or
     row-based replication is in use.

     Statement-based replication

     Tell the slave to restrict replication to statements where the
     default database (that is, the one selected by `USE') is DB_NAME.
     To specify more than one database, use this option multiple times,
     once for each database. Note that this does not replicate
     cross-database statements such as `UPDATE SOME_DB.SOME_TABLE SET
     foo='bar'' while having selected a different database or no
     database.

     *Warning*:

     To specify multiple databases you _must_ use multiple instances of
     this option. Because database names can contain commas, if you
     supply a comma separated list then the list will be treated as the
     name of a single database.

     An example of what does not work as you might expect when using
     statement-based replication: If the slave is started with
     `--replicate-do-db=sales' and you issue the following statements
     on the master, the `UPDATE' statement is _not_ replicated:

          USE prices;
          UPDATE sales.january SET amount=amount+1000;

     The main reason for this `just check the default database'
     behavior is that it is difficult from the statement alone to know
     whether it should be replicated (for example, if you are using
     multiple-table `DELETE' statements or multiple-table `UPDATE'
     statements that act across multiple databases). It is also faster
     to check only the default database rather than all databases if
     there is no need.

     Row-based replication

     Tell the slave to restrict replication to database DB_NAME. Only
     tables belonging to DB_NAME are changed; the current database has
     no effect on this. For example, suppose that the slave is started
     with `--replicate-do-db=sales' and row-based replication is in
     effect; then the following statements are run on the master:

          USE prices;
          UPDATE sales.february SET amount=amount+100;

     The `february' table in the `sales' database on the slave is
     changed in accordance with the `UPDATE' statement, and this takes
     place whether or not the `USE' statement was issued. However,
     issuing the following statements on the master has no effect on
     the slave when using row-based replication and
     `--replicate-do-db=sales':

          USE prices;
          UPDATE prices.march SET amount=amount-25;

     Even if the statement `USE prices' were changed to `USE sales', the
     `UPDATE' statement's effects would still not be replicated.

     Another importance difference in how `--replicate-do-db' is
     handled in statement-based replication as opposed to row-based
     replication occurs with regard to statements that refer to
     multiple databases. Suppose the slave is started with
     `--replicate-do-db=db1', and the following statements are executed
     on the master:

          USE db1;
          UPDATE db1.table1 SET col1 = 10, db2.table2 SET col2 = 20;

     If you are using statement-based replication, then both tables are
     updated on the slave. However, when using row-based replication,
     only `table1' is effected on the slave; since `table2' is in a
     different database, it is not changed by the `UPDATE'.  Now
     suppose that, instead of the `USE db1' statement, a `USE db4'
     statement was used:

          USE db4;
          UPDATE db1.table1 SET col1 = 10, db2.table2 SET col2 = 20;

     In this case, the `UPDATE' statement would have no effect on the
     slave when using statement-based replication. However, if using
     row-based replication, the `UPDATE' would change `table1' on the
     slave, but not `table2' -- in other words, only tables in the
     database named by `--replicate-do-db' are changed, and the choice
     of current database has no effect on this behavior.

     If you need cross-database updates to work, use
     `--replicate-wild-do-table=DB_NAME.%' instead. See *Note
     replication-rules::.

   *  `--replicate-do-table=DB_NAME.TBL_NAME'

     Tell the slave thread to restrict replication to the specified
     table. To specify more than one table, use this option multiple
     times, once for each table. This works for cross-database updates,
     in contrast to `--replicate-do-db'. See *Note replication-rules::.

   *  `--replicate-ignore-db=DB_NAME'

     As with `--replicate-do-db', the effects of this option depend on
     whether statement-based or row-based replication is in use.

     Statement-based replication

     Tells the slave to not replicate any statement where the default
     database (that is, the one selected by `USE') is DB_NAME.

     Row-based replication

     Tells the slave not to update any tables in the database DB_NAME.
     The current database has no effect.

     When using statement-based replication, the following example does
     not work as you might expect. Suppose that the slave is started
     with `--replicate-ignore-db=sales' and you issue the following
     statements on the master:

          USE prices;
          UPDATE sales.january SET amount=amount+1000;

     The `UPDATE' statement _is_ replicated in such a case because
     `--replicate-ignore-db' applies only to the default database
     (determined by the `USE' statement). Because the `sales' database
     was specified explicitly in the statement, the statement has not
     been filtered. However, when using row-based replication, the
     `UPDATE' statement's effects are _not_ propagated to the slave,
     and the slave's copy of the `sales.january' table is unchanged; in
     this instance, `--replicate-ignore-db=sales' causes _all_ changes
     made to tables in the master's copy of the `sales' database to be
     ignored by the slave.

     To specify more than one database to ignore, use this option
     multiple times, once for each database. Because database names can
     contain commas, if you supply a comma separated list then the list
     will be treated as the name of a single database.

     You should not use this option if you are using cross-database
     updates and you do not want these updates to be replicated.  See
     *Note replication-rules::.

     If you need cross-database updates to work, use
     `--replicate-wild-ignore-table=DB_NAME.%' instead. See *Note
     replication-rules::.

   *  `--replicate-ignore-table=DB_NAME.TBL_NAME'

     Tells the slave thread to not replicate any statement that updates
     the specified table, even if any other tables might be updated by
     the same statement. To specify more than one table to ignore, use
     this option multiple times, once for each table. This works for
     cross-database updates, in contrast to `--replicate-ignore-db'. See
     *Note replication-rules::.

   *  `--replicate-rewrite-db=FROM_NAME->TO_NAME'

     Tells the slave to translate the default database (that is, the
     one selected by `USE') to TO_NAME if it was FROM_NAME on the
     master. Only statements involving tables are affected (not
     statements such as `CREATE DATABASE', `DROP DATABASE', and `ALTER
     DATABASE'), and only if FROM_NAME is the default database on the
     master. This does not work for cross-database updates. To specify
     multiple rewrites, use this option multiple times. The server uses
     the first one with a FROM_NAME value that matches. The database
     name translation is done _before_ the `--replicate-*' rules are
     tested.

     If you use this option on the command line and the ``>'' character
     is special to your command interpreter, quote the option value.
     For example:

          shell> mysqld --replicate-rewrite-db="OLDDB->NEWDB"

   *  `--replicate-same-server-id'

     To be used on slave servers. Usually you should use the default
     setting of 0, to prevent infinite loops caused by circular
     replication. If set to 1, the slave does not skip events having
     its own server ID. Normally, this is useful only in rare
     configurations. Cannot be set to 1 if `--log-slave-updates' is
     used. Note that by default the slave I/O thread does not even
     write binary log events to the relay log if they have the slave's
     server id (this optimization helps save disk usage). So if you
     want to use `--replicate-same-server-id', be sure to start the
     slave with this option before you make the slave read its own
     events that you want the slave SQL thread to execute.

   *  `--replicate-wild-do-table=DB_NAME.TBL_NAME'

     Tells the slave thread to restrict replication to statements where
     any of the updated tables match the specified database and table
     name patterns. Patterns can contain the ``%'' and ``_'' wildcard
     characters, which have the same meaning as for the `LIKE'
     pattern-matching operator. To specify more than one table, use
     this option multiple times, once for each table. This works for
     cross-database updates. See *Note replication-rules::.

     Example: `--replicate-wild-do-table=foo%.bar%' replicates only
     updates that use a table where the database name starts with `foo'
     and the table name starts with `bar'.

     If the table name pattern is `%', it matches any table name and
     the option also applies to database-level statements (`CREATE
     DATABASE', `DROP DATABASE', and `ALTER DATABASE').  For example,
     if you use `--replicate-wild-do-table=foo%.%', database-level
     statements are replicated if the database name matches the pattern
     `foo%'.

     To include literal wildcard characters in the database or table
     name patterns, escape them with a backslash. For example, to
     replicate all tables of a database that is named `my_own%db', but
     not replicate tables from the `my1ownAABCdb' database, you should
     escape the ``_'' and ``%'' characters like this:
     `--replicate-wild-do-table=my\_own\%db'. If you're using the
     option on the command line, you might need to double the
     backslashes or quote the option value, depending on your command
     interpreter. For example, with the `bash' shell, you would need to
     type `--replicate-wild-do-table=my\\_own\\%db'.

   *  `--replicate-wild-ignore-table=DB_NAME.TBL_NAME'

     Tells the slave thread not to replicate a statement where any
     table matches the given wildcard pattern. To specify more than one
     table to ignore, use this option multiple times, once for each
     table. This works for cross-database updates. See *Note
     replication-rules::.

     Example: `--replicate-wild-ignore-table=foo%.bar%' does not
     replicate updates that use a table where the database name starts
     with `foo' and the table name starts with `bar'.

     For information about how matching works, see the description of
     the `--replicate-wild-do-table' option. The rules for including
     literal wildcard characters in the option value are the same as for
     `--replicate-wild-ignore-table' as well.

   *  `--report-host=SLAVE_NAME'

     The hostname or IP number of the slave to be reported to the
     master during slave registration. This value appears in the output
     of `SHOW SLAVE HOSTS' on the master server. Leave the value unset
     if you do not want the slave to register itself with the master.
     Note that it is not sufficient for the master to simply read the
     IP number of the slave from the TCP/IP socket after the slave
     connects. Due to NAT and other routing issues, that IP may not be
     valid for connecting to the slave from the master or other hosts.

   *  `--report-port=SLAVE_PORT_NUM'

     The TCP/IP port number for connecting to the slave, to be reported
     to the master during slave registration. Set this only if the
     slave is listening on a non-default port or if you have a special
     tunnel from the master or other clients to the slave. If you are
     not sure, do not use this option.

   *  `--report-password=PASSWORD'

     The account password of the slave to be reported to the master
     during slave registration. This value appears in the output of
     `SHOW SLAVE HOSTS' on the master server if the
     `--show-slave-auth-info' option is given.

   *  `--report-user=USER_NAME'

     The account username of the slave to be reported to the master
     during slave registration. This value appears in the output of
     `SHOW SLAVE HOSTS' on the master server if the
     `--show-slave-auth-info' option is given.

   *  `--show-slave-auth-info'

     Display slave usernames and passwords in the output of `SHOW SLAVE
     HOSTS' on the master server for slaves started with the
     `--report-user' and `--report-password' options.

   *  `--skip-slave-start'

     Tells the slave server not to start the slave threads when the
     server starts. To start the threads later, use a `START SLAVE'
     statement.

   *  `--slave_compressed_protocol={0|1}'

     If this option is set to 1, use compression for the slave/master
     protocol if both the slave and the master support it. The default
     is 0 (no compression).

   *  `--slave-load-tmpdir=FILE_NAME'

     The name of the directory where the slave creates temporary files.
     This option is by default equal to the value of the `tmpdir'
     system variable. When the slave SQL thread replicates a `LOAD DATA
     INFILE' statement, it extracts the file to be loaded from the relay
     log into temporary files, and then loads these into the table.  If
     the file loaded on the master is huge, the temporary files on the
     slave are huge, too. Therefore, it might be advisable to use this
     option to tell the slave to put temporary files in a directory
     located in some filesystem that has a lot of available space. In
     that case, the relay logs are huge as well, so you might also want
     to use the `--relay-log' option to place the relay logs in that
     filesystem.

     The directory specified by this option should be located in a
     disk-based filesystem (not a memory-based filesystem) because the
     temporary files used to replicate `LOAD DATA INFILE' must survive
     machine restarts. The directory also should not be one that is
     cleared by the operating system during the system startup process.

   *  `--slave-net-timeout=SECONDS'

     The number of seconds to wait for more data from the master before
     the slave considers the connection broken, aborts the read, and
     tries to reconnect. The first retry occurs immediately after the
     timeout. The interval between retries is controlled by the
     `MASTER_CONNECT_RETRY' option for the `CHANGE MASTER TO' statement
     or `--master-connect-retry' option, and the number of reconnection
     attempts is limited by the `--master-retry-count' option. The
     default is 3600 seconds (one hour).

   *  `--slave-skip-errors=[ERR_CODE1,ERR_CODE2,...|all]'

     Normally, replication stops when an error occurs on the slave.
     This gives you the opportunity to resolve the inconsistency in the
     data manually. This option tells the slave SQL thread to continue
     replication when a statement returns any of the errors listed in
     the option value.

     Do not use this option unless you fully understand why you are
     getting errors. If there are no bugs in your replication setup and
     client programs, and no bugs in MySQL itself, an error that stops
     replication should never occur. Indiscriminate use of this option
     results in slaves becoming hopelessly out of synchrony with the
     master, with you having no idea why this has occurred.

     For error codes, you should use the numbers provided by the error
     message in your slave error log and in the output of `SHOW SLAVE
     STATUS'.  *Note error-handling::, lists server error codes.

     You can also (but should not) use the very non-recommended value
     of `all' to cause the slave to ignore all error messages and keeps
     going regardless of what happens.  Needless to say, if you use
     `all', there are no guarantees regarding the integrity of your
     data. Please do not complain (or file bug reports) in this case if
     the slave's data is not anywhere close to what it is on the master.
     _You have been warned_.

     Examples:

          --slave-skip-errors=1062,1053
          --slave-skip-errors=all


File: manual.info,  Node: replication-administration,  Prev: replication-options,  Up: replication-configuration

19.1.4 Common Replication Administration Tasks
----------------------------------------------

* Menu:

* replication-administration-status::  Checking Replication Status
* replication-administration-pausing::  Pausing Replication on the Slave

Once replication has been started it should execute without requiring
much regular administration. Depending on your replication environment,
you will want to check the replication status of each slave either
periodically, daily, or even more frequently.

MySQL Enterprise

For regular reports regarding the status of your slaves, subscribe to
the MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: replication-administration-status,  Next: replication-administration-pausing,  Prev: replication-administration,  Up: replication-administration

19.1.4.1 Checking Replication Status
....................................

The most common task when managing a replication process is to ensure
that replication is taking place and that there have been no errors
between the slave and the master.

The primary command for this is `SHOW SLAVE STATUS' which you must
execute on each slave:

     mysql> SHOW SLAVE STATUS\G
     *************************** 1. row ***************************
                  Slave_IO_State: Waiting for master to send event
                     Master_Host: master1
                     Master_User: root
                     Master_Port: 3306
                   Connect_Retry: 60
                 Master_Log_File: mysql-bin.000004
             Read_Master_Log_Pos: 931
                  Relay_Log_File: slave1-relay-bin.000056
                   Relay_Log_Pos: 950
           Relay_Master_Log_File: mysql-bin.000004
                Slave_IO_Running: Yes
               Slave_SQL_Running: Yes
                 Replicate_Do_DB:
             Replicate_Ignore_DB:
              Replicate_Do_Table:
          Replicate_Ignore_Table:
         Replicate_Wild_Do_Table:
     Replicate_Wild_Ignore_Table:
                      Last_Errno: 0
                      Last_Error:
                    Skip_Counter: 0
             Exec_Master_Log_Pos: 931
                 Relay_Log_Space: 1365
                 Until_Condition: None
                  Until_Log_File:
                   Until_Log_Pos: 0
              Master_SSL_Allowed: No
              Master_SSL_CA_File:
              Master_SSL_CA_Path:
                 Master_SSL_Cert:
               Master_SSL_Cipher:
                  Master_SSL_Key:
           Seconds_Behind_Master: 0
     1 row in set (0.01 sec)

The key fields from the status report to examine are:

   * `Slave_IO_State' -- indicates the current status of the slave. See
     *Note slave-io-thread-states::, and *Note
     slave-sql-thread-states::, for more information.

   * `Slave_IO_Running' -- shows whether the IO thread for the reading
     the master's binary log is running.

   * `Slave_SQL_Running' -- shows whether the SQL thread for the
     executing events in the relay log is running.

   * `Last_Error' -- shows the last error registered when processing
     the relay log. Ideally this should be blank, indicating no errors.

   * `Seconds_Behind_Master' -- shows the number of seconds that the
     slave SQL thread is behind processing the master binary log. A
     high number (or an increasing one) can indicate that the slave is
     unable to cope with the large number of queries from the master.

     A value of 0 for `Seconds_Behind_Master' can usually be
     interpreted as meaning that the slave has caught up with the
     master, but there are some cases where this is not strictly true.
     For example, this can occur if the network connection between
     master and slave is broken but the slave I/O thread has not yet
     noticed this -- that is, `slave_net_timeout' has not yet elapsed.

     It is also possible that transient values for
     `Seconds_Behind_Master' may not reflect the situation accurately.
     When the slave SQL thread has caught up on I/O,
     `Seconds_Behind_Master' displays 0; but when the slave I/O thread
     is still queuing up a new event, `Seconds_Behind_Master' may show a
     large value until the SQL thread finishes executing the new event.
     This is especially likely when the events have old timestamps; in
     such cases, if you execute `SHOW SLAVE STATUS' several times in a
     relatively short peiod, you may see this value change back and
     forth repeatedly between 0 and a relatively large value.

On the master, you can check the status of slaves by examining the list
of running processes. Slaves execute the `Binlog Dump' command:

     mysql> SHOW PROCESSLIST \G;
     *************************** 4. row ***************************
          Id: 10
        User: root
        Host: slave1:58371
          db: NULL
     Command: Binlog Dump
        Time: 777
       State: Has sent all binlog to slave; waiting for binlog to be updated
        Info: NULL

Because it is the slave that drives the core of the replication
process, very little information is available in this report.

If you have used the `--report-host' option, then the `SHOW SLAVE
HOSTS' statement will show basic information about connected slaves:

     mysql> SHOW SLAVE HOSTS;
     +-----------+--------+------+-------------------+-----------+
     | Server_id | Host   | Port | Rpl_recovery_rank | Master_id |
     +-----------+--------+------+-------------------+-----------+
     |        10 | slave1 | 3306 |                 0 |         1 |
     +-----------+--------+------+-------------------+-----------+
     1 row in set (0.00 sec)

The output includes the ID of the slave server, the value of the
`--report-host' option, the connecting port, master ID and the priority
of the slave for receiving binary log updates.


File: manual.info,  Node: replication-administration-pausing,  Prev: replication-administration-status,  Up: replication-administration

19.1.4.2 Pausing Replication on the Slave
.........................................

You can stop and start the replication of statements on the slave using
the `STOP SLAVE' and `START SLAVE' commands.

To stop execution of the binary log from the master, use `STOP SLAVE':

     mysql> STOP SLAVE;

When execution is stopped, the slave does not read the binary log from
the master (the `IO_THREAD') and stops processing events from the relay
log that have not yet been executed (the `SQL_THREAD'). You can pause
either the IO or SQL threads individually by specifying the thread
type. For example:

     mysql> STOP SLAVE IO_THREAD;

Stopping the SQL thread can be useful if you want to perform a backup
or other task on a slave that only processes events from the master.
The IO thread will continue to be read from the master, but not
executed, which will make it easier for the slave to catch up when you
start slave operations again.

Stopping the IO thread will allow the statements in the relay log to be
executed up until the point where the relay log has ceased to receive
new events. Using this option can be useful when you want to pause
execution to allow the slave to catch up with events from the master,
when you want to perform administration on the slave but also ensure
you have the latest updates to a specific point. This method can also
be used to pause execution on the slave while you conduct
administration on the master while ensuring that there is not a massive
backlog of events to be executed when replication is started again.

To start execution again, use the `START SLAVE' statement:

     mysql> START SLAVE;

If necessary, you can start either the `IO_THREAD' or `SQL_THREAD'
threads individually.


File: manual.info,  Node: replication-solutions,  Next: replication-notes,  Prev: replication-configuration,  Up: replication

19.2 Replication Solutions
==========================

* Menu:

* replication-solutions-backups::  Using Replication for Backups
* replication-solutions-diffengines::  Using Replication with Different Master and Slave Storage Engines
* replication-solutions-scaleout::  Using Replication for Scale-Out
* replication-solutions-partitioning::  Replicating Different Databases to Different Slaves
* replication-solutions-performance::  Improving Replication Performance
* replication-solutions-switch::  Switching Masters During Failover
* replication-solutions-ssl::    Setting Up Replication Using SSL

Replication can be used in many different environments for a range of
purposes. In this section you will find general notes and advice on
using replication for specific solution types.

For information on using replication in a backup environment, including
notes on the setup, backup procedure, and files to back up, see *Note
replication-solutions-backups::.

For advice and tips on using different storage engines on the master
and slaves, see *Note replication-solutions-diffengines::.

Using replication as a scale-out solution requires some changes in the
logic and operation of applications that use the solution. See *Note
replication-solutions-scaleout::.

For performance or data distribution reasons you may want to replicate
different databases to different replication slaves. See *Note
replication-solutions-partitioning::

As the number of replication slaves increases, the load on the master
can increase (because of the need to replicate the binary log to each
slave) and lead to a reduction in performance of the master.  For tips
on improving your replication performance, including using a single
secondary server as an replication master, see *Note
replication-solutions-performance::.

For guidance on switching masters, or converting slaves into masters as
part of an emergency failover solution, see *Note
replication-solutions-switch::.

To secure your replication communication you can encrypt the
communication channel by using SSL to exchange data. Step-by-step
instructions can be found in *Note replication-solutions-ssl::.


File: manual.info,  Node: replication-solutions-backups,  Next: replication-solutions-diffengines,  Prev: replication-solutions,  Up: replication-solutions

19.2.1 Using Replication for Backups
------------------------------------

* Menu:

* replication-solutions-backups-mysqldump::  Backing Up a Slave Using `mysqldump'
* replication-solutions-backups-rawdata::  Backing Up Raw Data from a Slave
* replication-solutions-backups-read-only::  Backing Up a Master or Slave by Making It Read Only

You can use replication as a backup solution by replicating data from
the master to a slave, and then backing up the data slave.  Because the
slave can be paused and shut down without affecting the running
operation of the master you can produce an effective snapshot of 'live'
data that would otherwise require a shutdown of the master database.

How you back up the database will depend on the size of the database
and whether you are backing up only the data, or the data and the
replication slave state so that you can rebuild the slave in the event
of failure. There are therefore two choices:

If you are using replication as a solution to enable you to back up the
data on the master, and the size of your database is not too large,
then the `mysqldump' tool may be suitable. See *Note
replication-solutions-backups-mysqldump::.

For larger databases, where `mysqldump' would be impractical or
inefficient, you can back up the raw data files instead. Using the raw
data files option also means that you can back up the binary and relay
logs that will enable you to recreate the slave in the event of a slave
failure. For more information, see *Note
replication-solutions-backups-rawdata::.

Another backup strategy, which can be used for either master or slave
servers, is to put the server in a read-only state. The backup is
performed against the read-only server, which then is changed back to
its usual read/write operational status. See *Note
replication-solutions-backups-read-only::.


File: manual.info,  Node: replication-solutions-backups-mysqldump,  Next: replication-solutions-backups-rawdata,  Prev: replication-solutions-backups,  Up: replication-solutions-backups

19.2.1.1 Backing Up a Slave Using `mysqldump'
.............................................

Using `mysqldump' to create a copy of the database enables you to
capture all of the data in the database in a format that allows the
information to be imported into another instance of MySQL. Because the
format of the information is SQL statements the file can easily be
distributed and applied to running servers in the event that you need
access to the data in an emergency. However, if the size of your data
set is very large then `mysqldump' may be impractical.

When using `mysqldump' you should stop the slave before starting the
dump process to ensure that the dump contains a consistent set of data:

  1. Stop the slave from processing requests. You can either stop the
     slave completely using `mysqladmin':

          shell> mysqladmin stop-slave

     Alternatively, you can stop processing the relay log files by
     stopping the replication SQL thread. Using this method will allow
     the binary log data to be transferred. Within busy replication
     environments this may speed up the catch-up process when you start
     the slave processing again:

          shell> mysql -e 'STOP SLAVE SQL_THREAD;'

  2. Run `mysqldump' to dump your databases. You may either select
     databases to be dumped, or dump all databases. For more
     information, see *Note mysqldump::. For example, to dump all
     databases:

          shell> mysqldump --all-databases >fulldb.dump

  3. Once the dump has completed, start slave operations again:

          shell> mysqladmin start-slave

In the preceding example you may want to add login credentials
(username, password) to the commands, and bundle the process up into a
script that you can run automatically each day.

If you use this approach, make sure you monitor the slave replication
process to ensure that the time taken to run the backup in this way is
not affecting the slave's ability to keep up with events from the
master. See *Note replication-administration-status::. If the slave is
unable to keep up you may want to add another server and distribute the
backup process. For an example of how to configure this scenario, see
*Note replication-solutions-partitioning::.


File: manual.info,  Node: replication-solutions-backups-rawdata,  Next: replication-solutions-backups-read-only,  Prev: replication-solutions-backups-mysqldump,  Up: replication-solutions-backups

19.2.1.2 Backing Up Raw Data from a Slave
.........................................

To guarantee the integrity of the files that are copied, backing up the
raw data files on your MySQL replication slave should take place while
your slave server is shut down. If the MySQL server is still running
then background tasks, particularly with storage engines with
background processes such as InnoDB, may still be updating the database
files. With InnoDB, these problems should be resolved during crash
recovery, but since the slave server can be shut down during the backup
process without affecting the execution of the master it makes sense to
take advantage of this facility.

To shut down the server and back up the files:

  1. Shut down the slave MySQL server:

          shell> mysqladmin shutdown

  2. Copy the data files. You can use any suitable copying or archive
     utility, including `cp', `tar' or `WinZip':

          shell> tar cf /tmp/dbbackup.tar ./data

  3. Start up the `mysqld' process again:

          shell> mysqld_safe &

     Under Windows:

          C:\> "C:\Program Files\MySQL\MySQL Server 5.1\bin\mysqld"

Normally you should back up the entire data folder for the slave MySQL
server. If you want to be able to restore the data and operate as a
slave (for example, in the event of failure of the slave), then when
you back up the slave's data, you should back up the slave status
files, `master.info' and `relay.info', along with the relay log files.
These files are needed to resume replication after you restore the
slave's data.

If you lose the relay logs but still have the `relay-log.info' file,
you can check it to determine how far the SQL thread has executed in
the master binary logs. Then you can use `CHANGE MASTER TO' with the
`MASTER_LOG_FILE' and `MASTER_LOG_POS' options to tell the slave to
re-read the binary logs from that point. Of course, this requires that
the binary logs still exist on the master server.

If your slave is subject to replicating `LOAD DATA INFILE' statements,
you should also back up any `SQL_LOAD-*' files that exist in the
directory that the slave uses for this purpose. The slave needs these
files to resume replication of any interrupted `LOAD DATA INFILE'
operations. The directory location is specified using the
`--slave-load-tmpdir' option. If this option is not specified, the
directory location is the value of the `tmpdir' system variable.


File: manual.info,  Node: replication-solutions-backups-read-only,  Prev: replication-solutions-backups-rawdata,  Up: replication-solutions-backups

19.2.1.3 Backing Up a Master or Slave by Making It Read Only
............................................................

It is possible to back up either master or slave servers in a
replication setup by acquiring a global read lock and manipulating the
`read_only' system variable to change the read-only state of the server
to be backed up:

  1. Make the server read-only, so that it processes only retrievals
     and blocks updates

  2. Perform the backup

  3. Change the server back to its normal read/write state

The following instructions describe how to do this for a master server
and for a slave server.

These instructions require MySQL 5.1.15 or higher. For earlier
versions, setting `read_only' did not block while table locks or
outstanding transactions were pending, so that some data changes could
still occur during the backup.

*Note*:

The instructions in this section place the server to be backed up in a
state that is safe for backup methods that get the data from the
server, such as `mysqldump' (see *Note mysqldump::). You should not
attempt to use these instructions to make a binary backup by copying
files directly because the server may still have modified data cached
in memory and not flushed to disk.

For both scenarios discussed here, suppose that you have the following
replication setup:

   * A master server M1

   * A slave server S1 that has M1 as its master

   * A client C1 connected to M1

   * A client C2 connected to S1

*Scenario 1: Backup with a Read-Only Master*

Put the master M1 in a read-only state by executing these statements on
it:

     FLUSH TABLES WITH READ LOCK;
     SET GLOBAL read_only = ON;

While M1 is in a read-only state, the following properties are true:

   * Requests for updates sent by C1 to M1 will fail because the server
     is in read-only mode

   * Requests for retrievals sent by C1 to M1 will succeed

   * Making a backup on M1 is safe

   * Making a backup on S1 is not safe: this server is still running,
     and might be processing the binary log or update requests coming
     from client C2 (S1 might not be in a read-only state)

While M1 is read only, perform the backup. For example, you can use
`mysqldump'.

After the backup on M1 has been done, restore M1 to its normal
operational state by executing these statements:

     SET GLOBAL read_only = OFF;
     UNLOCK TABLES;

Although performing the backup on M1 is safe (as far as the backup is
concerned), it is not optimal because clients of M1 are blocked from
executing updates.

This strategy also applies to backing up a single server in a
non-replication setting.

*Scenario 2: Backup with a Read-Only Slave*

Put the slave S1 in a read-only state by executing these statements on
it:

     FLUSH TABLES WITH READ LOCK;
     SET GLOBAL read_only = ON;

While S1 is in a read-only state, the following properties are true:

   * The master M1 will continue to operate

   * Making a backup on the master is not safe

   * The slave S1 is stopped

   * Making a backup on the slave S1 is safe

These properties provide the basis for a popular backup scenario:
Having one slave busy performing a backup for a while is not a problem
because it does not affect the entire network, and the system is still
running during the backup. (For example, clients can still perform
updates on the master server.)

While S1 is read only, perform the backup.

After the backup on S1 has been done, restore S1 to its normal
operational state by executing these statements:

     SET GLOBAL read_only = OFF;
     UNLOCK TABLES;

After the slave is restored to normal operation, it again synchronizes
to the master by catching up with any outstanding updates in the binary
log from the master.

In either scenario, the statements to acquire the global read lock and
manipulate the `read_only' variable are performed on the server to be
backed up and do not propagate to any slaves of that server.


File: manual.info,  Node: replication-solutions-diffengines,  Next: replication-solutions-scaleout,  Prev: replication-solutions-backups,  Up: replication-solutions

19.2.2 Using Replication with Different Master and Slave Storage Engines
------------------------------------------------------------------------

The replication process does not care if the source table on the master
and the replicated table on the slave use different engine types. In
fact, the system variables `storage_engine' and `table_type' are not
replicated.

This provides a number of advantages in the replication process in that
you can take advantage of different engine types for different
replication scenarios. For example, in a typical scaleout scenario (see
*Note replication-solutions-scaleout::), you want to use `InnoDB'
tables on the master to take advantage of the transactional
functionality, but use `MyISAM' on the slaves where transaction support
is not required because the data is only read. When using replication
in a data logging environment you may want to use the `Archive' storage
engine on the slave.

Setting up different engines on the master and slave depends on how you
set up the initial replication process:

   * If you used `mysqldump' to create the database snapshot on your
     master then you could edit the dump text to change the engine type
     used on each table.

     Another alternative for `mysqldump' is to disable engine types
     that you do not want to use on the slave before using the dump to
     build the data on the slave. For example, you can add the
     `--skip-innodb' option on your slave to disable the `InnoDB'
     engine.  If a specific engine does not exist, MySQL will use the
     default engine type, usually `MyISAM'. If you want to disable
     further engines in this way, you may want to consider building a
     special binary to be used on the slave that only supports the
     engines you want.

   * If you are using raw data files for the population of the slave,
     you will be unable to change the initial table format.  Instead,
     use `ALTER TABLE' to change the table types after the slave has
     been started.

   * For new master/slave replication setups where there are currently
     no tables on the master, avoid specifying the engine type when
     creating new tables.

If you are already running a replication solution and want to convert
your existing tables to another engine type, follow these steps:

  1. Stop the slave from running replication updates:

          mysql> STOP SLAVE;

     This will enable you to change engine types without interruptions.

  2. Execute an `ALTER TABLE ...  Engine='ENGINETYPE'' for each table
     where you want to change the engine type.

  3. Start the slave replication process again:

          mysql> START SLAVE;

Although the `storage_engine' and `table_type' variables are not
replicated, be aware that `CREATE TABLE' and `ALTER TABLE' statements
that include the engine specification will be correctly replicated to
the slave. For example, if you have a CSV table and you execute:

     mysql> ALTER TABLE csvtable Engine='MyISAM';

The above statement will be replicated to the slave and the engine type
on the slave will be converted to `MyISAM', even if you have previously
changed the table type on the slave to an engine other than CSV. If you
want to retain engine differences on the master and slave, you should
be careful to use the `storage_engine' variable on the master when
creating a new table. For example, instead of:

     mysql> CREATE TABLE tablea (columna int) Engine=MyISAM;

Use this format:

     mysql> SET storage_engine=MyISAM;
     mysql> CREATE TABLE tablea (columna int);

When replicated, the `storage_engine' variable will be ignored, and the
`CREATE TABLE' statement will be executed with the slave's default
engine type.


File: manual.info,  Node: replication-solutions-scaleout,  Next: replication-solutions-partitioning,  Prev: replication-solutions-diffengines,  Up: replication-solutions

19.2.3 Using Replication for Scale-Out
--------------------------------------

You can use replication as a scale-out solution, i.e. where you want to
split up the load of database queries across multiple database servers,
within some reasonable limitations.

Because replication works from the distribution of one master to one or
more slaves, using replication for scaleout works best in an
environment where you have a high number of reads and low number of
writes/updates. Most websites fit into this category, where users are
browsing the website, reading articles, posts, or viewing products.
Updates only occur during session management, or when making a purchase
or adding a comment/message to a forum.

Replication in this situation enables you to distribute the reads over
the replication slaves, while still allowing your web servers to
communicate with the replication master when a write is required. You
can see a sample replication layout for this scenario in *Note
figure_replication-scaleout::.

FIGURE GOES HERE: Using replication to improve the performance during
scaleout

If the part of your code that is responsible for database access has
been properly abstracted/modularized, converting it to run with a
replicated setup should be very smooth and easy. Change the
implementation of your database access to send all writes to the
master, and to send reads to either the master or a slave. If your code
does not have this level of abstraction, setting up a replicated system
gives you the opportunity and motivation to clean it up. Start by
creating a wrapper library or module that implements the following
functions:

   * `safe_writer_connect()'

   * `safe_reader_connect()'

   * `safe_reader_statement()'

   * `safe_writer_statement()'

`safe_' in each function name means that the function takes care of
handling all error conditions. You can use different names for the
functions. The important thing is to have a unified interface for
connecting for reads, connecting for writes, doing a read, and doing a
write.

Then convert your client code to use the wrapper library. This may be a
painful and scary process at first, but it pays off in the long run.
All applications that use the approach just described are able to take
advantage of a master/slave configuration, even one involving multiple
slaves. The code is much easier to maintain, and adding troubleshooting
options is trivial. You need modify only one or two functions; for
example, to log how long each statement took, or which statement among
those issued gave you an error.

If you have written a lot of code, you may want to automate the
conversion task by using the `replace' utility that comes with standard
MySQL distributions, or write your own conversion script. Ideally, your
code uses consistent programming style conventions. If not, then you
are probably better off rewriting it anyway, or at least going through
and manually regularizing it to use a consistent style.


File: manual.info,  Node: replication-solutions-partitioning,  Next: replication-solutions-performance,  Prev: replication-solutions-scaleout,  Up: replication-solutions

19.2.4 Replicating Different Databases to Different Slaves
----------------------------------------------------------

There may be situations where you have a single master and want to
replicate different databases to different slaves. For example, you may
want to distribute different sales data to different departments to
help spread the load during data analysis. A sample of this layout is
shown in *Note figure_replication-multi-db::.

FIGURE GOES HERE: Using replication to replicate separate DBs to
multiple hosts

You can achieve this separation by configuring the master and slaves as
normal, and then limiting the binary log statements that each slave
processes by using the `replicate-wild-do-table' configuration option on
each slave.

For example, to support the separation as shown in *Note
figure_replication-multi-db::, you would configure each slave as
follows before enabling replication using `START SLAVE':

   * MySQL Slave 1 should have the following configuration options:

          replicate-wild-do-table=sales.%
          replicate-wild-do-table=finance.%

   * MySQL Slave 2 should have the following configuration option:

          replicate-wild-do-table=support.%

   * MySQL Slave 3 should have the following configuration option:

          replicate-wild-do-table=service.%

If you have data that needs to be synchronized to the slaves before
replication starts, you have a number of options:

   * Synchronize all the data to each slave, and delete the databases
     and/or tables that you do not want to keep.

   * Use `mysqldump' to create a separate dump file for each database
     and load the appropriate dump file on each slave.

   * Use a raw data file dump and include only the specific files and
     databases that you need for each slave. This option will not work
     with InnoDB databases unless you use the `innodb_file_per_table'
     option.

Each slave in this configuration will transfer to the entire binary log
from the master, but will only execute the events within the binary log
that apply to the configured databases and tables.


File: manual.info,  Node: replication-solutions-performance,  Next: replication-solutions-switch,  Prev: replication-solutions-partitioning,  Up: replication-solutions

19.2.5 Improving Replication Performance
----------------------------------------

As the number of slaves connecting to a master increases, the load,
although minimal, also increases, as each slave uses up a client
connection to the master. Also, as each slave must receive a full copy
of the master binary log, the network load on the master may also
increase and start to create a bottleneck.

If you are using a large number of slaves connected to one master, and
that master is also busy processing requests (for example, as part of a
scaleout solution), then you may want to improve the performance of the
replication process.

One way to improve the performance of the replication process is to
create a deeper replication structure that enables the master to
replicate to only one slave, and for the remaining slaves to connect to
this primary slave for their individual replication requirements. A
sample of this structure is shown in *Note
figure_replication-performance::.

FIGURE GOES HERE: Using an additional replication host to improve
performance

For this to work, you must configure the MySQL instances as follows:

   * Master 1 is the primary master where all changes and updates are
     written to the database. Binary logging should be enabled on this
     machine.

   * Master 2 is the slave to the Master 1 that provides the
     replication functionality to the remainder of the slaves in the
     replication structure. Master 2 is the only machine allowed to
     connect to Master 1. Master 2 also has binary logging enabled, and
     the `--log-slave-updates' option so that replication instructions
     from Master 1 are also written to Master 2's binary log so that
     they can then be replicated to the true slaves.

   * Slave 1, Slave 2, and Slave 3 act as slaves to Master 2, and
     replicate the information from Master 2, which is really the data
     logged on Master 1.

The above solution reduces the client load and the network interface
load on the primary master, which should improve the overall
performance of the primary master when used as a direct database
solution.

If your slaves are having trouble keeping up with the replication
process on the master then there are a number of options available:

   * If possible, you should put the relay logs and the data files on
     different physical drives. To do this, use the `--relay-log'
     option to specify the location of the relay log.

   * If the slaves are significantly slower than the master, then you
     may want to divide up the responsibility for replicating different
     databases to different slaves. See *Note
     replication-solutions-partitioning::.

   * If your master makes use of transactions and you are not concerned
     about transaction support on your slaves, then use `MyISAM' or
     another non-transactional engine.  See *Note
     replication-solutions-diffengines::.

   * If your slaves are not acting as masters, and you have a potential
     solution in place to ensure that you can bring up a master in the
     event of failure, then you can switch off `--log-slave-updates'.
     This prevents 'dumb' slaves from also logging events they have
     executed into their own binary log.


File: manual.info,  Node: replication-solutions-switch,  Next: replication-solutions-ssl,  Prev: replication-solutions-performance,  Up: replication-solutions

19.2.6 Switching Masters During Failover
----------------------------------------

There is currently no official solution for providing failover between
master and slaves in the event of a failure. With the currently
available features, you would have to set up a master and a slave (or
several slaves), and to write a script that monitors the master to
check whether it is up. Then instruct your applications and the slaves
to change master in case of failure.

Remember that you can tell a slave to change its master at any time,
using the `CHANGE MASTER TO' statement. The slave will not check
whether the databases on the master are compatible with the slave, it
will just start executing events from the specified log and postition
on the new master. In a failover situation all the servers in the group
are probably executing the same events from the same binary log, so
changing the source of the events should not affect the database
structure or integrity providing you are careful.

Run your slaves with the `--log-bin' option and without
`--log-slave-updates'. In this way, the slave is ready to become a
master as soon as you issue `STOP SLAVE'; `RESET MASTER', and `CHANGE
MASTER TO' statement on the other slaves. For example, assume that you
have the structure shown in *Note
figure_replication-redundancy-before::.

FIGURE GOES HERE: Redundancy using replication, initial structure

In this diagram, the `MySQL Master' holds the master database, the
`MySQL Slave' computers are replication slaves, and the `Web Client'
machines are issuing database reads and writes. Web clients that issue
only reads (and would normally be connected to the slaves) are not
shown, as they do not need to switch to a new server in the event of
failure. For a more detailed example of a read/write scaleout
replication structure, see *Note replication-solutions-scaleout::.

Each MySQL Slave (`Slave 1', `Slave 2', and `Slave 3') are slaves
running with `--log-bin' and without `--log-slave-updates'. Because
updates received by a slave from the master are not logged in the
binary log unless `--log-slave-updates' is specified, the binary log on
each slave is empty initially. If for some reason `MySQL Master'
becomes unavailable, you can pick one of the slaves to become the new
master. For example, if you pick `Slave 1', all `Web Clients' should be
redirected to `Slave 1', which will log updates to its binary log.
`Slave 2' and `Slave 3' should then replicate from `Slave 1'.

The reason for running the slave without `--log-slave-updates' is to
prevent slaves from receiving updates twice in case you cause one of
the slaves to become the new master. Suppose that `Slave 1' has
`--log-slave-updates' enabled. Then it will write updates that it
receives from `Master' to its own binary log. When `Slave 2' changes
from `Master' to `Slave 1' as its master, it may receive updates from
`Slave 1' that it has already received from `Master'

Make sure that all slaves have processed any statements in their relay
log. On each slave, issue `STOP SLAVE IO_THREAD', then check the output
of `SHOW PROCESSLIST' until you see `Has read all relay log'. When this
is true for all slaves, they can be reconfigured to the new setup. On
the slave `Slave 1' being promoted to become the master, issue `STOP
SLAVE' and `RESET MASTER'.

On the other slaves `Slave 2' and `Slave 3', use `STOP SLAVE' and
`CHANGE MASTER TO MASTER_HOST='Slave1'' (where `'Slave1'' represents
the real hostname of `Slave 1'). To `CHANGE MASTER', add all
information about how to connect to `Slave 1' from `Slave 2' or `Slave
3' (USER, PASSWORD, PORT). In `CHANGE MASTER', there is no need to
specify the name of `Slave 1''s binary log or binary log position to
read from: We know it is the first binary log and position 4, which are
the defaults for `CHANGE MASTER'.  Finally, use `START SLAVE' on `Slave
2' and `Slave 3'.

Once the new replication is in place, you will then need to instruct
each `Web Client' to direct their statements to `Slave 1'. From that
point on, all updates statements sent by `Web Client' to `Slave 1' are
written to the binary log of `Slave 1', which then contains every update
statement sent to `Slave 1' since `Master' died.

The resulting server structure is shown in *Note
figure_replication-redundancy-after::.

FIGURE GOES HERE: Redundancy using replication, after master failure

When `Master' is up again, you must issue on it the same `CHANGE
MASTER' as that issued on `Slave 2' and `Slave 3', so that `Master'
becomes a slave of `S1' and picks up each `Web Client' writes that it
missed while it was down.

To make `Master' a master again (because it is the most powerful
machine, for example), use the preceding procedure as if `Slave 1' was
unavailable and `Master' was to be the new master. During this
procedure, do not forget to run `RESET MASTER' on `Master' before
making `Slave 1', `Slave 2', and `Slave 3' slaves of `Master'.
Otherwise, they may pick up old `Web Client' writes from before the
point at which `Master' became unavailable.

Note that there is no synchronization between the different slaves to a
master. Some slaves might be ahead of others. This means that the
concept outlined in the previous example might not work. In practice,
however, the relay logs of different slaves will most likely not be far
behind the master, so it would work, anyway (but there is no guarantee).

A good way to keep your applications informed as to the location of the
master is by having a dynamic DNS entry for the master.  With `bind'
you can use `nsupdate' to dynamically update your DNS.


File: manual.info,  Node: replication-solutions-ssl,  Prev: replication-solutions-switch,  Up: replication-solutions

19.2.7 Setting Up Replication Using SSL
---------------------------------------

Setting up replication using an SSL connection is similar to setting up
a server and client using SSL. You will need to obtain (or create) a
suitable security certificate that you can use on the master, and a
similar certificate (from the same certificate authority) on each slave.

To use SSL for encrypting the transfer of the binary log required
during replication you must first set up the master to support SSL
network connections. If the master does not support SSL connections
(because it has not been compiled or configured for SSL), then
replication through an SSL connection will not be possible.

For more information on setting up a server and client for SSL
connectivity, see *Note secure-using-ssl::.

To enable SSL on the master you will need to create or obtain suitable
certficates and then add the following configuration options to the
master's configuration within the `mysqld' section:

     ssl-ca=CACERT.PEM
     ssl-cert=SERVER-CERT.PEM
     ssl-key=SERVER-KEY.PEM

*Note*:

You should use full path to specify the location of your certificate
files.

The options are as follows:

   * `ssl-ca' identifies the Certificate Authority (CA) certificate.

   * `ssl-cert' identifies the server public key.  This can be sent to
     the client and authenticated against the CA certificate that it
     has.

   * `ssl-key' identifies the server private key.

On the slave, you have two options available for setting the SSL
information. You can either add the slaves certificates to the `client'
section of the slave configuration file, or you can explicitly specify
the SSL information using the `CHANGE MASTER' statement.

Using the former option, add the following lines to the `client'
section of the slave configuration file:

     [client]
     ssl-ca=CACERT.PEM
     ssl-cert=SERVER-CERT.PEM
     ssl-key=SERVER-KEY.PEM

Restart the slave server, using the `--skip-slave' to prevent the slave
from connecting to the master. Use `CHANGE MASTER' to specify the
master configuration, using the `master_ssl' option to enable SSL
connectivity:

     mysql> CHANGE MASTER TO \
         MASTER_HOST='master_hostname', \
         MASTER_USER='replicate', \
         MASTER_PASSWORD='password', \
         MASTER_SSL=1;

To specify the SSL certificate options during the `CHANGE MASTER'
command, append the SSL options:

     CHANGE MASTER TO \
           MASTER_HOST='master_hostname', \
           MASTER_USER='replicate', \
           MASTER_PASSWORD='password', \
           MASTER_SSL=1, \
           MASTER_SSL_CA = 'ca_file_name', \
           MASTER_SSL_CAPATH = 'ca_directory_name', \
           MASTER_SSL_CERT = 'cert_file_name', \
           MASTER_SSL_KEY = 'key_file_name';

Once the master information has been updated, start the slave
replication process:

     mysql> START SLAVE;

You can use the `SHOW SLAVE STATUS' to confirm that SSL connection has
been completed.

For more information on the `CHANGE MASTER TO' syntax, see *Note
change-master-to::.

If you want to enforce SSL connections to be used during replication,
then create a user with the `REPLICATION SLAVE' privilege and use the
`REQUIRE_SSL' option for that user. For example:

     mysql> GRANT REPLICATION SLAVE ON *.*
         -> TO 'repl'@'%.mydomain.com' IDENTIFIED BY 'slavepass' REQUIRE SSL;


File: manual.info,  Node: replication-notes,  Next: replication-implementation,  Prev: replication-solutions,  Up: replication

19.3 Replication Notes and Tips
===============================

* Menu:

* replication-features::         Replication Features and Issues
* replication-compatibility::    Replication Compatibility Between MySQL Versions
* replication-upgrade::          Upgrading a Replication Setup
* replication-faq::              Replication FAQ
* replication-problems::         Troubleshooting Replication
* replication-bugs::             How to Report Replication Bugs or Problems


File: manual.info,  Node: replication-features,  Next: replication-compatibility,  Prev: replication-notes,  Up: replication-notes

19.3.1 Replication Features and Issues
--------------------------------------

* Menu:

* replication-features-auto-increment::  Replication and `AUTO_INCREMENT'
* replication-features-charset::  Replication and Character Sets
* replication-features-create-select::  Replication of `CREATE TABLE ... SELECT' Statements
* replication-features-directory::  Replication and `DIRECTORY' Statements
* replication-features-invoked::  Replication of Invoked Features
* replication-features-floatvalues::  Replication with Floating-Point Values
* replication-features-flush::   Replication and `FLUSH'
* replication-features-functions::  Replication and System Functions
* replication-features-limit::   Replication and `LIMIT'
* replication-features-load-data::  Replication and `LOAD DATA'
* replication-features-mastercrash::  Replication During a Master Crash
* replication-features-mastershutdown::  Replication During a Master Shutdown
* replication-features-memory::  Replication with `MEMORY' Tables
* replication-features-mysqldb::  Replication of the System `mysql' Database
* replication-features-reserved-words::  Replication and Reserved Words
* replication-features-slaveerrors::  Slave Errors during Replication
* replication-features-slaveshutdown::  Replication during a Slave Shutdown
* replication-features-temptables::  Replication and Temporary Tables
* replication-features-timeout::  Replication Retries and Timeouts
* replication-features-timezone::  Replication and Time Zones
* replication-features-transactions::  Replication and Transactions
* replication-features-differing-tables::  Replication with Differing Tables on Master and Slave
* replication-features-variables::  Replication and Variables
* replication-features-views::   Replication and Views

In general, replication compatibility at the SQL level requires that
any features used be supported by both the master and the slave
servers. If you use a feature on a master server that is available only
as of a given version of MySQL, you cannot replicate to a slave that is
older than that version. Such incompatibilities are likely to occur
between series, so that, for example, you cannot replicate from MySQL
5.1 to 5.0. However, these incompatibilities also can occur for
within-series replication. For example, the `SLEEP()' function is
available in MySQL 5.0.12 and up. If you use this function on the master
server, you cannot replicate to a slave server that is older than MySQL
5.0.12.

If you are planning to use replication between 5.1 and a previous
version of MySQL you should consult the edition of the MySQL Reference
Manual corresponding to the earlier release series for information
regarding the replication characteristics of that series.

The following sections provide details about what is supported and what
is not, and about specific issues and situations that may occur when
replicating certain statements. Additional information specific to
`InnoDB' and replication is given in *Note
innodb-and-mysql-replication::. For information relating to replication
with MySQL Cluster, see *Note mysql-cluster-replication::.

With MySQL's classic statement-based replication, there may be issues
with replicating stored routines or triggers. You can avoid these
issues by using MySQL's row-based replication instead. For a detailed
list of issues, see *Note stored-procedure-logging::. For a description
of row-based replication, see *Note replication-formats::.


File: manual.info,  Node: replication-features-auto-increment,  Next: replication-features-charset,  Prev: replication-features,  Up: replication-features

19.3.1.1 Replication and `AUTO_INCREMENT'
.........................................

Replication of `AUTO_INCREMENT', `LAST_INSERT_ID()', and `TIMESTAMP'
values is done correctly, subject to the following exceptions.

A stored procedure that uses `LAST_INSERT_ID()' does not replicate
properly using statement-based binary logging. This limitation is
lifted in MySQL 5.1.12.

Prior to MySQL 5.1.12, when a stored routine or trigger caused an
`INSERT' into an `AUTO_INCREMENT' column, the generated
`AUTO_INCREMENT' value was not written into the binary log, so a
different value could in some cases be inserted on the slave.

An insert into an `AUTO_INCREMENT' column caused by a stored routine or
trigger running on a master that uses MySQL 5.0.60 or earlier does not
replicate correctly to a slave running MySQL 5.1.12 through 5.1.23
(inclusive). (Bug#33029 (http://bugs.mysql.com/33029))

Adding an `AUTO_INCREMENT' column to a table with `ALTER TABLE' might
not produce the same ordering of the rows on the slave and the master.
This occurs because the order in which the rows are numbered depends on
the specific storage engine used for the table and the order in which
the rows were inserted. If it is important to have the same order on
the master and slave, the rows must be ordered before assigning an
`AUTO_INCREMENT' number.  Assuming that you want to add an
`AUTO_INCREMENT' column to the table `t1', the following statements
produce a new table `t2' identical to `t1' but with an `AUTO_INCREMENT'
column:

     CREATE TABLE t2 LIKE t1;
     ALTER TABLE t2 ADD id INT AUTO_INCREMENT PRIMARY KEY;
     INSERT INTO t2 SELECT * FROM t1 ORDER BY col1, col2;

This assumes that the table `t1' has columns `col1' and `col2'.

*Important*:

To guarantee the same ordering on both master and slave, _all_ columns
of `t1' must be referenced in the `ORDER BY' clause.

The instructions just given are subject to the limitations of `CREATE
TABLE ... LIKE': Foreign key definitions are ignored, as are the `DATA
DIRECTORY' and `INDEX DIRECTORY' table options. If a table definition
includes any of those characteristics, create `t2' using a `CREATE
TABLE' statement that is identical to the one used to create `t1', but
with the addition of the `AUTO_INCREMENT' column.

Regardless of the method used to create and populate the copy having
the `AUTO_INCREMENT' column, the final step is to drop the original
table and then rename the copy:

     DROP t1;
     ALTER TABLE t2 RENAME t1;

See also *Note alter-table-problems::.


File: manual.info,  Node: replication-features-charset,  Next: replication-features-create-select,  Prev: replication-features-auto-increment,  Up: replication-features

19.3.1.2 Replication and Character Sets
.......................................

The following applies to replication between MySQL servers that use
different character sets:

  1. If the master uses MySQL 4.1, you must _always_ use the same
     _global_ character set and collation on the master and the slave,
     regardless of the MySQL version running on the slave. (These are
     controlled by the `--character-set-server' and
     `--collation-server' options.) Otherwise, you may get
     duplicate-key errors on the slave, because a key that is unique in
     the master character set might not be unique in the slave
     character set. Note that this is not a cause for concern when
     master and slave are both MySQL 5.0 or later.

  2. If the master is older than MySQL 4.1.3, the character set of any
     client should never be made different from its global value
     because this character set change is not known to the slave. In
     other words, clients should not use `SET NAMES', `SET CHARACTER
     SET', and so forth. If both the master and the slave are 4.1.3 or
     newer, clients can freely set session values for character set
     variables because these settings are written to the binary log and
     so are known to the slave. That is, clients can use `SET NAMES' or
     `SET CHARACTER SET' or can set variables such as
     `collation_client' or `collation_server'. However, clients are
     prevented from changing the _global_ value of these variables; as
     stated previously, the master and slave must always have identical
     global character set values. This is true wther you are using
     statement-based or row-based replication.

  3. If you have databases on the master with character sets that
     differ from the global `character_set_server' value, you should
     design your `CREATE TABLE' statements so that tables in those
     databases do not implicitly rely on the database default character
     set. A good workaround is to state the character set and collation
     explicitly in `CREATE TABLE' statements.


File: manual.info,  Node: replication-features-create-select,  Next: replication-features-directory,  Prev: replication-features-charset,  Up: replication-features

19.3.1.3 Replication of `CREATE TABLE ... SELECT' Statements
............................................................

The following rules and decisions are applied when a `CREATE TABLE ...
SELECT' statement is replicated:

   * All `CREATE TABLE ... SELECT' statements do implicit commit.

   * If there are no failures, then all `CREATE TABLE ...  SELECT'
     statements are replicated as follows:

        * For `STATEMENT' and `MIXED' format, as the `CREATE TABLE ...
          SELECT' statement itself.

        * For `ROW' format, as a `CREATE TABLE' statement followed by
          binwrite events.

   * Requirements for `CREATE TABLE t2 SELECT ...' using both
     transactional and non-transactional tables:

        * For `STATEMENT', `MIXED', and `ROW' formats:

             * If the table already exists, then the statement does
               nothing on the master, and only the implicit commit is
               logged.

             * If other execution failure (and thus `t2' did not
               exist), then the table is never created on master and
               only the implicit commit is logged.

   * Requirements for `CREATE TABLE IF NOT EXISTS t2 SELECT ...'

        * For `STATEMENT' and `MIXED' format:

          If execution failure, then statement is logged with error
          code.

        * For `ROW' format when t2 is transactional:

             * If table already exists, then

                  * The `CREATE TABLE' part of the statement is not
                    logged.

                  * All applied rows are logged.

                  * The implicit commit is logged.

             * If other failure in creating table, then only the
               implicit commit is logged.

             * If failure in selecting or inserting (but create
               succeeded), then the table is dropped on master and only
               the implicit commit is logged.

        * For `ROW' format when t2 is non-transactional:

             * If table already exists, then:

                  * the `CREATE TABLE' part of the statement is not
                    logged.

                  * All applied rows are logged.

                  * The implicit commit is logged.

             * If other failure in creating table, then only the
               implicit commit is logged.

             * If failure in selecting or inserting (but create
               succeeded), then:

                  * The `CREATE TABLE' part of the statement is logged.

                  * All applied rows are logged.

                  * The implicit commit is logged.


File: manual.info,  Node: replication-features-directory,  Next: replication-features-invoked,  Prev: replication-features-create-select,  Up: replication-features

19.3.1.4 Replication and `DIRECTORY' Statements
...............................................

If a `DATA DIRECTORY' or `INDEX DIRECTORY' table option is used in a
`CREATE TABLE' statement on the master server, the table option is also
used on the slave. This can cause problems if no corresponding
directory exists in the slave host filesystem or if it exists but is
not accessible to the slave server. MySQL supports an `sql_mode' option
called `NO_DIR_IN_CREATE'. If the slave server is run with this SQL
mode enabled, it ignores the `DATA DIRECTORY' and `INDEX DIRECTORY'
table options when replicating `CREATE TABLE' statements. The result is
that `MyISAM' data and index files are created in the table's database
directory.


File: manual.info,  Node: replication-features-invoked,  Next: replication-features-floatvalues,  Prev: replication-features-directory,  Up: replication-features

19.3.1.5 Replication of Invoked Features
........................................

Replication of invoked features such as scheduled events, user-defined
functions (UDFs), stored routines (including both stored procedures and
stored functions), and triggers was re-implemented in MySQL 5.1.18 to
provide the following characteristics:

   * The effects of the feature are always replicated.

   * The following statements are replicated using statement-based
     replication:

        * `CREATE EVENT'

        * `ALTER EVENT'

        * `DROP EVENT'

        * `CREATE PROCEDURE'

        * `DROP PROCEDURE'

        * `CREATE FUNCTION'

        * `DROP FUNCTION'

        * `CREATE TRIGGER'

        * `DROP TRIGGER'

     However, the _effects_ of features created, modified, or dropped
     using these statements are replicated using row-based replication.

   * In the case of `CREATE EVENT' and `ALTER EVENT':

        * The status of the event is set to `SLAVESIDE_DISABLED' on the
          slave regardless of the state specified (this does not apply
          to `DROP EVENT').

        * The master on which the event was created is identified on
          the slave by its server ID. The `ORIGINATOR' column in
          `INFORMATION_SCHEMA.EVENTS' and the `originator' column in
          `mysql.event' were added to these tables in MySQL 5.1.18 to
          store this information.  (See *Note events-table::, and *Note
          show-events::.)

   * The feature implementation resides on the slave in a renewable
     state so that if the master fails, the slave can be used as the
     master without loss of event processing.

To determine whether there are any scheduled events on a MySQL server
that were created on a different server (that was acting as a
replication master), use `SHOW EVENTS', like this:

     SHOW EVENTS
         WHERE STATUS = 'SLAVESIDE_DISABLED';

Alternatively, you might wish to query the `INFORMATION_SCHEMA.EVENTS'
table as shown here:

     SELECT EVENT_SCHEMA, EVENT_NAME, ORIGINATOR
         FROM INFORMATION_SCHEMA.EVENTS
         WHERE STATUS = 'SLAVESIDE_DISABLED';

When promoting a replication slave having such events to a replication
master, use the following query to enable the events:

     UPDATE mysql.event
         SET STATUS = 'ENABLED'
         WHERE STATUS = 'SLAVESIDE_DISABLED';

If more than one master was involved in creating events on this slave,
and you wish to enable events that were created only on a given master
having the server ID MASTER_ID, use the following query instead:

     UPDATE mysql.event
         SET STATUS = 'ENABLED'
         WHERE ORIGINATOR = MASTER_ID
         AND STATUS = 'SLAVESIDE_DISABLED';

*Important*:

Before executing either of the previous two `UPDATE' statements, you
should disable the Event Scheduler on the slave (using `SET GLOBAL
EVENT_SCHEDULER = OFF;'), run the `UPDATE', restart the server, then
re-enable the Event Scheduler afterwards (using `SET GLOBAL
EVENT_SCHEDULER = ON;').

If you later demote the new master back to being a replication slave,
you must disable manually all events enabled by the `UPDATE' statement.
You can do this by storing in a separate table the event names from the
`SELECT' statement shown previously, or using an `UPDATE' statement to
rename the events with a common prefix to identify them, as shown in
this example:

     UPDATE mysql.event
         SET name = CONCAT('replicated_', name)
         WHERE status = 'SLAVESIDE_DISABLED';

When demoting this server back to being a replication slave, you can
then rename and disable the events like this:

     UPDATE mysql.event
         SET name = REPLACE(name, 'replicated_', ''),
             status = 'SLAVESIDE_DISABLED'
         WHERE INSTR(name, 'replicated_') = 1;


File: manual.info,  Node: replication-features-floatvalues,  Next: replication-features-flush,  Prev: replication-features-invoked,  Up: replication-features

19.3.1.6 Replication with Floating-Point Values
...............................................

Floating-point values are approximate, so comparisons involving them
are inexact. This is true for operations that use floating-point values
explicitly, or values that are converted to floating-point implicitly.
Comparisons of floating-point values might yield different results on
master and slave servers due to differences in computer architecture,
the compiler used to build MySQL, and so forth. See *Note
type-conversion::, and *Note problems-with-float::.


File: manual.info,  Node: replication-features-flush,  Next: replication-features-functions,  Prev: replication-features-floatvalues,  Up: replication-features

19.3.1.7 Replication and `FLUSH'
................................

Some forms of the `FLUSH' statement are not logged because they could
cause problems if replicated to a slave: `FLUSH LOGS', `FLUSH MASTER',
`FLUSH SLAVE', and `FLUSH TABLES WITH READ LOCK'. For a syntax example,
see *Note flush::. The `FLUSH TABLES', `ANALYZE TABLE', `OPTIMIZE
TABLE', and `REPAIR TABLE' statements are written to the binary log and
thus replicated to slaves. This is not normally a problem because these
statements do not modify table data. However, this can cause
difficulties under certain circumstances. If you replicate the
privilege tables in the `mysql' database and update those tables
directly without using `GRANT', you must issue a `FLUSH PRIVILEGES' on
the slaves to put the new privileges into effect. In addition, if you
use `FLUSH TABLES' when renaming a `MyISAM' table that is part of a
`MERGE' table, you must issue `FLUSH TABLES' manually on the slaves.
These statements are written to the binary log unless you specify
`NO_WRITE_TO_BINLOG' or its alias `LOCAL'.


File: manual.info,  Node: replication-features-functions,  Next: replication-features-limit,  Prev: replication-features-flush,  Up: replication-features

19.3.1.8 Replication and System Functions
.........................................

Certain functions do not replicate well under some conditions:

   * The `USER()', `CURRENT_USER()', `UUID()', `VERSION()', and
     `LOAD_FILE()' functions are replicated without change and thus do
     not work reliably on the slave unless row-based replication is
     enabled. This is also true for `CURRENT_USER'.  (See *Note
     replication-formats::.)

     For early implementations of mixed-format logging, stored
     functions, triggers, and views that use these functions in their
     body do not replicate reliably in mixed-format logging mode
     because the logging did not switch from statement-based to
     row-based format. For example, `INSERT INTO t SELECT FROM v',
     where `v' is a view that selects `UUID()' could cause problems.
     This limitation is lifted in MySQL 5.1.12.

     Beginning with MySQL 5.1.23, `USER()', `CURRENT_USER()', and
     `CURRENT_USER' are automatically replicated using row-based
     replication when using `MIXED' mode, and generate a warning in
     `STATEMENT' mode. (Bug#28086 (http://bugs.mysql.com/28086))

   * For `NOW()', the binary log includes the timestamp and replicates
     correctly.

     Unlike `NOW()', the `SYSDATE()' function is not replication-safe
     because it is not affected by `SET TIMESTAMP' statements in the
     binary log and is non-deterministic if statement-based logging is
     used. This is not a problem if row-based logging is used. Another
     option is to start the server with the `--sysdate-is-now' option
     to cause `SYSDATE()' to be an alias for `NOW()'.

   * _The following restriction applies to statement-based replication
     only, not to row-based replication._ The `GET_LOCK()',
     `RELEASE_LOCK()', `IS_FREE_LOCK()', and `IS_USED_LOCK()' functions
     that handle user-level locks are replicated without the slave
     knowing the concurrency context on master. Therefore, these
     functions should not be used to insert into a master's table
     because the content on the slave would differ. (For example, do
     not issue a statement such as `INSERT INTO mytable
     VALUES(GET_LOCK(...))'.)

As a workaround for the preceding limitations when statement-based
replication is in effect, you can use the strategy of saving the
problematic function result in a user variable and referring to the
variable in a later statement. For example, the following single-row
`INSERT' is problematic due to the reference to the `UUID()' function:

     INSERT INTO t VALUES(UUID());

To work around the problem, do this instead:

     SET @my_uuid = UUID();
     INSERT INTO t VALUES(@my_uuid);

That sequence of statements replicates because the value of `@my_uuid'
is stored in the binary log as a user-variable event prior to the
`INSERT' statement and is available for use in the `INSERT'.

The same idea applies to multiple-row inserts, but is more cumbersome
to use. For a two-row insert, you can do this:

     SET @my_uuid1 = UUID(); @my_uuid2 = UUID();
     INSERT INTO t VALUES(@my_uuid1),(@my_uuid2);

However, if the number of rows is large or unknown, the workaround is
difficult or impracticable. For example, you cannot convert the
following statement to one in which a given individual user variable is
associated with each row:

     INSERT INTO t2 SELECT UUID(), * FROM t1;

Within a stored function, `RAND()' replicates correctly as long as it
is invoked only once within the function. (You can consider the
function execution timestamp and random number seed as implicit inputs
that are identical on the master and slave.)

The `FOUND_ROWS()' and `ROW_COUNT()' functions are not replicated
reliably using statement-based replication. A workaround is to store
the result of the function call in a user variable, and then use that
in the `INSERT' statement. For example, if you wish to store the result
in a table named `mytable', you might normally do so like this:


     SELECT SQL_CALC_FOUND_ROWS FROM mytable LIMIT 1;
     INSERT INTO mytable VALUES( FOUND_ROWS() );

However, if you are replicating `mytable', then you should use `SELECT
INTO', and then store the variable in the table, like this:


     SELECT SQL_CALC_FOUND_ROWS INTO @found_rows FROM mytable LIMIT 1;
     INSERT INTO mytable VALUES(@found_rows);

In this way, the user variable is replicated as part of the context,
and applied on the slave correctly.

Beginning with MySQL 5.1.23, these functions are automatically
replicated using row-based replication when using `MIXED' mode, and
generate a warning in `STATEMENT' mode. (Bug#12092
(http://bugs.mysql.com/12092), Bug#30244 (http://bugs.mysql.com/30244))


File: manual.info,  Node: replication-features-limit,  Next: replication-features-load-data,  Prev: replication-features-functions,  Up: replication-features

19.3.1.9 Replication and `LIMIT'
................................

Statement-based replication of `LIMIT' clauses in `DELETE', `UPDATE',
and `INSERT ... SELECT' statements is unsafe since the order of the
rows affected is not defined. Beginning with MySQL 5.1.24, when such a
statement is encountered:

   * when using `STATEMENT' mode, a warning that the statement is not
     safe for statement-based replication is now issued

   * when using `MIXED' mode, the statement is now automatically
     replicated using row-based mode


File: manual.info,  Node: replication-features-load-data,  Next: replication-features-mastercrash,  Prev: replication-features-limit,  Up: replication-features

19.3.1.10 Replication and `LOAD DATA'
.....................................

The `LOAD DATA' statement is not replicated correctly to a slave
running MySQL 5.1 or later from a master running MySQL 4.0 or earlier.

When using statement-based replication, the `LOAD DATA INFILE'
statement's `CONCURRENT' option is not replicated; that is, `LOAD DATA
CONCURRENT INFILE' is replicated as `LOAD DATA INFILE', and `LOAD DATA
CONCURRENT LOCAL INFILE' is replicated as `LOAD DATA LOCAL INFILE'. The
`CONCURRENT' option _is_ replicated when using row-based replication.
(Bug#34628 (http://bugs.mysql.com/34628))


File: manual.info,  Node: replication-features-mastercrash,  Next: replication-features-mastershutdown,  Prev: replication-features-load-data,  Up: replication-features

19.3.1.11 Replication During a Master Crash
...........................................

A crash on the master side can result in the master's binary log having
a final position less than the most recent position read by the slave,
due to the master's binary log file not being flushed. This can cause
the slave not to be able to replicate when the master comes back up.
Setting `sync_binlog=1' in the master `my.cnf' file helps to minimize
this problem because it causes the master to flush its binary log more
frequently.


File: manual.info,  Node: replication-features-mastershutdown,  Next: replication-features-memory,  Prev: replication-features-mastercrash,  Up: replication-features

19.3.1.12 Replication During a Master Shutdown
..............................................

It is safe to shut down a master server and restart it later.  When a
slave loses its connection to the master, the slave tries to reconnect
immediately and retries periodically if that fails.  The default is to
retry every 60 seconds. This may be changed with the `CHANGE MASTER TO'
statement or `--master-connect-retry' option. A slave also is able to
deal with network connectivity outages. However, the slave notices the
network outage only after receiving no data from the master for
`slave_net_timeout' seconds. If your outages are short, you may want to
decrease `slave_net_timeout'. See *Note server-system-variables::.


File: manual.info,  Node: replication-features-memory,  Next: replication-features-mysqldb,  Prev: replication-features-mastershutdown,  Up: replication-features

19.3.1.13 Replication with `MEMORY' Tables
..........................................

When a server shuts down and restarts, its `MEMORY' tables become
empty. The master replicates this effect to slaves as follows: The
first time that the master uses each `MEMORY' table after startup, it
logs an event that notifies the slaves that the table needs to be
emptied by writing a `DELETE' statement for that table to the binary
log. See *Note memory-storage-engine::, for more information about
`MEMORY' tables.


File: manual.info,  Node: replication-features-mysqldb,  Next: replication-features-reserved-words,  Prev: replication-features-memory,  Up: replication-features

19.3.1.14 Replication of the System `mysql' Database
....................................................

MySQL 5.1.14 and later

Data modification statements made to tables in the `mysql' database are
replicated according to the value of `binlog_format'; if this value is
`MIXED', then these statement are replicated using the row-based
format. However, statements that would normally update this information
indirectly -- such `GRANT', `REVOKE', and statements manipulating
triggers, stored routines, and views -- are replicated to slaves using
statement-based replication.

MySQL 5.1.13 and earlier

User privileges are replicated only if the `mysql' database is
replicated. That is, the `GRANT', `REVOKE', `SET PASSWORD', `CREATE
USER', and `DROP USER' statements take effect on the slave only if the
replication setup includes the `mysql' database.


File: manual.info,  Node: replication-features-reserved-words,  Next: replication-features-slaveerrors,  Prev: replication-features-mysqldb,  Up: replication-features

19.3.1.15 Replication and Reserved Words
........................................

You can encounter problems when you are attempting to replicate from an
older master to a newer slave and you make use of identifiers on the
master that are reserved words in the newer MySQL version running on
the slave. An example of this is using a table column named
`current_user' on a 4.0 master that is replicating to a 4.1 or higher
slave, because `CURRENT_USER' is a reserved word beginning in MySQL
4.1. Replication can fail in such cases with Error 1064 `You have an
error in your SQL syntax...', _even if a database or table named using
the reserved word or a table having a column named using the reserved
word is excluded from replication_. This is due to the fact that each
SQL statement must be parsed by the slave prior to execution, so that
the slave knows which database object or objects would be effected by
the statement; only after the statement is parsed can the slave apply
any filtering rules defined by `--replicate-do-db',
`--replicate-do-table', `--replicate-ignore-db', and
`--replicate-ignore-ignore'.

To work around the problem of database, table, or column names on the
master which would be regarded as reserved words by the slave, do one
of the following:

   * Use one or more `ALTER TABLE' statements on the master to change
     the names of any database objects where these names would be
     considered reserved words on the slave, and change any SQL
     statements that use the old names to use the new names instead.

   * In any SQL statements using these database object names, set the
     names off using backtick characters (``').

For listings of reserved words by MySQL version, see Reserved Words
(http://dev.mysql.com/doc/mysqld-version-reference/en/mysqld-version-reference-optvar.html),.in
the `MySQL Server Version Reference'.


File: manual.info,  Node: replication-features-slaveerrors,  Next: replication-features-slaveshutdown,  Prev: replication-features-reserved-words,  Up: replication-features

19.3.1.16 Slave Errors during Replication
.........................................

If a statement on a slave produces an error, the slave SQL thread
terminates, and the slave writes a message to its error log. You should
then connect to the slave manually and determine the cause of the
problem. (`SHOW SLAVE STATUS' is useful for this.) Then fix the problem
(for example, you might need to create a non-existent table) and run
`START SLAVE'.

MySQL Enterprise

For instant notification when a slave thread terminates subscribe to
the MySQL Enterprise Monitor. For more information see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: replication-features-slaveshutdown,  Next: replication-features-temptables,  Prev: replication-features-slaveerrors,  Up: replication-features

19.3.1.17 Replication during a Slave Shutdown
.............................................

Shutting down the slave (cleanly) is also safe because it keeps track
of where it left off. Unclean shutdowns might produce problems,
especially if the disk cache was not flushed to disk before the system
went down. Your system fault tolerance is greatly increased if you have
a good uninterruptible power supply. Unclean shutdowns of the master
may cause inconsistencies between the content of tables and the binary
log in master; this can be avoided by using `InnoDB' tables and the
`--innodb-safe-binlog' option on the master. See *Note binary-log::.


File: manual.info,  Node: replication-features-temptables,  Next: replication-features-timeout,  Prev: replication-features-slaveshutdown,  Up: replication-features

19.3.1.18 Replication and Temporary Tables
..........................................

This item does not apply when row-based replication is in use because
in that case temporary tables are not replicated (see *Note
replication-formats::).

Safe shutdown of slaves when using temporary tables

Temporary tables are replicated except in the case where you shut down
the slave server (not just the slave threads) and you have replicated
temporary tables that are used in updates that have not yet been
executed on the slave. If you shut down the slave server, the temporary
tables needed by those updates are no longer available when the slave
is restarted. To avoid this problem, do not shut down the slave while
it has temporary tables open. Instead, use the following procedure:

  1. Issue a `STOP SLAVE' statement.

  2. Use `SHOW STATUS' to check the value of the
     `Slave_open_temp_tables' variable.

  3. If the value is 0, issue a `mysqladmin shutdown' command to stop
     the slave.

  4. If the value is not 0, restart the slave SQL thread with `START
     SLAVE SQL_THREAD'.

  5. Repeat the procedure later until the `Slave_open_temp_tables'
     variable is 0 and you can stop the slave.

Temporary tables and replication options

By default, all temporary tables are replicated; this happens whether
or not there are any matching `--replicate-do-db',
`--replicate-do-table', or `--replicate-wild-do-table' options in
effect.  However, the `--replicate-ignore-table' and
`--replicate-wild-ignore-table' options are honored for temporary
tables.

A recommended practice when using statement-based or mixed-format
replication is to designate a prefix for exclusive use in naming
temporary tables that you do not want replicated, then employ a matching
`--replicate-wild-ignore-table' option. For example, you might give all
such tables names beginning with `norep_' (such as `norep_tablea',
`norep_tableb', and so on), then use
`--replicate-wild-ignore-table=norep_' to prevent the replication of
these tables.


File: manual.info,  Node: replication-features-timeout,  Next: replication-features-timezone,  Prev: replication-features-temptables,  Up: replication-features

19.3.1.19 Replication Retries and Timeouts
..........................................

The global system variable `slave_transaction_retries' affects
replication as follows: If the replication slave SQL thread fails to
execute a transaction because of an `InnoDB' deadlock or because it
exceeded the `InnoDB' `innodb_lock_wait_timeout' value, or the
`NDBCLUSTER' `TransactionDeadlockDetectionTimeout' or
`TransactionInactiveTimeout' value, the transaction is automatically
retried `slave_transaction_retries' times before stopping with an
error. The default value is 10. The total retry count can be seen in
the output of `SHOW STATUS'; see *Note server-status-variables::.


File: manual.info,  Node: replication-features-timezone,  Next: replication-features-transactions,  Prev: replication-features-timeout,  Up: replication-features

19.3.1.20 Replication and Time Zones
....................................

If the master uses MySQL 4.1, the same system time zone should be set
for both master and slave. Otherwise some statements will not be
replicated properly, such as statements that use the `NOW()' or
`FROM_UNIXTIME()' functions. You can set the time zone in which MySQL
server runs by using the `--timezone=TIMEZONE_NAME' option of the
`mysqld_safe' script or by setting the `TZ' environment variable. Both
master and slave should also have the same default connection time zone
setting; that is, the `--default-time-zone' parameter should have the
same value for both master and slave. Note that this is not necessary
when the master is MySQL 5.0 or later.

`CONVERT_TZ(...,...,@@session.time_zone)' is properly replicated only
if both master and slave are running MySQL 5.0.4 or newer.


File: manual.info,  Node: replication-features-transactions,  Next: replication-features-differing-tables,  Prev: replication-features-timezone,  Up: replication-features

19.3.1.21 Replication and Transactions
......................................

It is possible to replicate transactional tables on the master using
non-transactional tables on the slave. For example, you can replicate
an `InnoDB' master table as a `MyISAM' slave table. However, if you do
this, there are problems if the slave is stopped in the middle of a
`BEGIN'/`COMMIT' block because the slave restarts at the beginning of
the `BEGIN' block.

In situations where transactions mix updates to transactional and
non-transactional tables, the order of statements in the binary log is
correct, and all needed statements are written to the binary log even
in case of a `ROLLBACK'.  However, when a second connection updates the
non-transactional table before the first connection's transaction is
complete, statements can be logged out of order, because the second
connection's update is written immediately after it is performed,
regardless of the state of the transaction being performed by the first
connection.

Due to the non-transactional nature of `MyISAM' tables, it is possible
to have a statement that only partially updates a table and returns an
error code. This can happen, for example, on a multiple-row insert that
has one row violating a key constraint, or if a long update statement
is killed after updating some of the rows. If that happens on the
master, the slave thread exits and waits for the database administrator
to decide what to do about it unless the error code is legitimate and
execution of the statement results in the same error code on the slave.
If this error code validation behavior is not desirable, some or all
errors can be masked out (ignored) with the `--slave-skip-errors'
option.

*Caution*:

You should not use transactions in a replication environment that
update both transactional and non-transactional tables.

When the storage engine type of the slave is non-transactional,
transactions on the master that mix updates of transactional and
non-transactional tables should be avoided because they can cause
inconsistency of the data between the master's transactional table and
the slave's non-transactional table.  That is, such transactions can
lead to master storage engine-specific behavior with the possible
effect of replication going out of synchrony. MySQL does not issue a
warning about this currently, so extra care should be taken when
replicating transactional tables from the master to non-transactional
ones on the slaves.


File: manual.info,  Node: replication-features-differing-tables,  Next: replication-features-variables,  Prev: replication-features-transactions,  Up: replication-features

19.3.1.22 Replication with Differing Tables on Master and Slave
...............................................................

* Menu:

* replication-features-more-columns::  Replication with More Columns on Master or Slave
* replication-features-different-data-types::  Replication of Columns Having Different Data Types

Starting with MySQL 5.1.21, source and target tables for replication do
not have to be identical. A table on the master can have more or fewer
columns than the slave's copy of the table. In addition -- subject to
certain conditions -- corresponding table columns on the master and the
slave can use different data types.

In all cases where the source and target tables do not have identical
definitions, the following must be true in order for replication to
work:

   * You must be using row-based replication. (Using `MIXED' for the
     binary logging format does not work.)

   * The database and table names must be the same on both the master
     and the slave.

Additional conditions are discussed (and examples provided) in the
following two sections.


File: manual.info,  Node: replication-features-more-columns,  Next: replication-features-different-data-types,  Prev: replication-features-differing-tables,  Up: replication-features-differing-tables

19.3.1.23 Replication with More Columns on Master or Slave
..........................................................

Starting with MySQL 5.1.21, you can replicate a table from the master
to the slave such that the master's copy of the table and the slave's
copy of the table do not have the same number of columns, subject to
the following conditions:

   * Each `extra' column in the version of the table having more
     columns must have a default value.

     *Note*:

     A column's default value is determined by a number of factors,
     including its type, whether it is defined with a `DEFAULT' option,
     whether it is declared as `NULL', and the server SQL mode in
     effect at the time of its creation; see *Note
     data-type-defaults::), for more information.

   * Matching columns must be defined in the same order on both the
     master and the slave.

   * Any additional columns must be defined following the matching
     columns.

In addition, when the slave's copy of the table has more columns than
the master's copy, then each matching column must use the same data
type.

Examples

The following examples illustrate some valid and invalid table
definitions:

   * More columns on the master

     The following table definitions are valid:

          master> CREATE TABLE t1 (c1 INT, c2 INT, c3 INT);
          slave>  CREATE TABLE t1 (c1 INT, c2 INT);

     The following table definitions would raise Error 1532
     (ER_BINLOG_ROW_RBR_TO_SBR) because the definitions of the columns
     common to both versions of the table are in a different order on
     the slave than they are on the master:

          master> CREATE TABLE t1 (c1 INT, c2 INT, c3 INT);
          slave>  CREATE TABLE t1 (c2 INT, c1 INT);

     The following table definitions would also raise Error 1532,
     because the definition of the extra column on the master appears
     before the definitions of the columns common to both versions of
     the table:

          master> CREATE TABLE t1 (c3 INT, c1 INT, c2 INT);
          slave>  CREATE TABLE t1 (c1 INT, c2 INT);

   * More columns on the slave

     The following definitions replicate correctly:

          master> CREATE TABLE t1 (c1 INT, c2 INT);
          slave>  CREATE TABLE t1 (c1 INT, c2 INT, c3 INT);

     The following definitions raise Error 1532 because the columns
     common to both versions of the table are not defined in the same
     order on both the master and the slave:

          master> CREATE TABLE t1 (c1 INT, c2 INT);
          slave>  CREATE TABLE t1 (c2 INT, c1 INT, c3 INT);

     The following table definitions also raise Error 1532 because the
     definition for the extra column in the slave's version of the
     table appears before the definitions for the columns which are
     common to both versions of the table:

          master> CREATE TABLE t1 (c1 INT, c2 INT);
          slave>  CREATE TABLE t1 (c3 INT, c1 INT, c2 INT);

     The following table definitions fail, because the slave's version
     of the table has additional columns compared to the master's
     version, and the two versions of the table define column `c2' as a
     different data type.

          master> CREATE TABLE t1 (c1 INT, c2 BIGINT);
          slave>  CREATE TABLE t1 (c1 INT, c2 INT, c3 INT);


File: manual.info,  Node: replication-features-different-data-types,  Prev: replication-features-more-columns,  Up: replication-features-differing-tables

19.3.1.24 Replication of Columns Having Different Data Types
............................................................

Corresponding columns on the master's and the slave's copies of the
same table ideally should have the same data type. However, beginning
with MySQL 5.1.21, this is not always strictly enforced, as long as
certain conditions are met. These conditions are listed here:

   * The slave's copy of the table cannot contain more columns than the
     master's copy.

   * For columns holding numeric data types, the sizes may differ, as
     long as the size of the the slave's version of the column is equal
     or greater to the size of the master's version of the column. This
     is sometimes referred to as _attribute promotion_, because the
     data type of the master's version of the column is promoted to a
     type that is the same size or larger on the slave.

     Data type conversions currently supported by attribute promotion
     are shown in the following table, in which X and N both represent
     positive integers:

     Original Data Type                 Promoted Data Type(s)
     `CHAR(X)'                          `CHAR(X+N)'
     `VARCHAR(X)'                       `VARCHAR(X+N)'
     `CHAR(X)'                          `VARCHAR(X+N)'
     `BINARY(X)'                        `BINARY(X+N)'
     `VARBINARY(X)'                     `VARBINARY(X+N)'
     `BINARY(X)'                        `VARBINARY(X+N)'
     `BIT(X) '                          `BIT(X+N)'
     `TINYINT'                          `SMALLINT', `MEDIUMINT', `INT', or
                                        `BIGINT'
     `SMALLINT'                         `MEDIUMINT', `INT', or `BIGINT'
     `MEDIUMINT'                        `INT' or `BIGINT'
     `INT'                              `BIGINT'

     Unsigned integer columns can be promoted to larger unisgned types;
     for example, a column declared as `TINYINT UNSIGNED' can be
     restored to a column declared as `SMALLINT UNSIGNED', `MEDIUMINT
     UNSIGNED', `INT UNSIGNED', or `BIGINT UNSIGNED'. You cannot
     promote a signed column to an unsigned type, or an unsigned column
     to a signed type.

     For example, the following table definitions are allowed:

          master> CREATE TABLE t1 (c1 TINYINT, c2 INT);
          slave>  CREATE TABLE t1 (c1 INT,     c2 INT);

     The slave's versions of both columns `c1' and `c2' are the same
     size as or larger than the master's versions of these columns.
     However, the following definitions would fail:

          master> CREATE TABLE t1 (c1 INT, c2 FLOAT(8,3));
          slave>  CREATE TABLE t1 (c1 INT, c2 FLOAT(7,3));

     In this case, Error 1532 would be raised because the master's copy
     of column `c2' is larger than its counterpart on the slave -- that
     is, the master's copy of `c2' on the master can hold more digits
     than the slave's copy of the column.

   * There is no conversion between integer (`TINYINT', `SMALLINT',
     `MEDIUMINT', and so on) and non-integer (`FLOAT', `DOUBLE',
     `DECIMAL', and so on) numeric data types, and so the following
     definitions would fail with Error 1532:

          master> CREATE TABLE t1 (c1 INT, c2 FLOAT(8,3));
          slave>  CREATE TABLE t1 (c1 INT, c2 BIGINT);

     A column using a non-integer numeric data type must always have
     the same definition on both the master and the slave.

   * For columns storing `CHAR' and `BINARY' data, the size of the
     slave's copy of the column must be equal to or greater than the
     size of the master's copy. For example, the following table
     definitions would replicate successfully:

          master> CREATE TABLE t1 (c1 INT, c2 CHAR(30));
          slave>  CREATE TABLE t1 (c1 INT, c2 CHAR(50));

     If the size of the master's version of the column is greater than
     that of the slave's version of the column, replication fails with
     Error 1532.

   * The replication process can convert freely between `BINARY',
     `VARBINARY', `CHAR' and `VARCHAR' columns, as long as the slave's
     version of the column is the same size as or larger than the
     master's version. For example, the following table definitions can
     be used successfully:

          master> CREATE TABLE t1 (c1 INT, c2 VARBINARY(30));
          slave>  CREATE TABLE t1 (c1 INT, c2 CHAR(30));

     *Note*:

     Since replication is currently not supported between different
     character sets, it is sufficient when comparing sizes of columns
     containing character data to count the number of characters rather
     than the number of bytes.

   * Attribute promotion can be used with both statement-based and
     row-based replication, and is not dependent on the storage engine
     used by either the master or the slave.


File: manual.info,  Node: replication-features-variables,  Next: replication-features-views,  Prev: replication-features-differing-tables,  Up: replication-features

19.3.1.25 Replication and Variables
...................................

The `FOREIGN_KEY_CHECKS', `UNIQUE_CHECKS', and `SQL_AUTO_IS_NULL'
variables are all replicated.

`SQL_MODE' is also replicated except for the `NO_DIR_IN_CREATE' mode.
However, when `mysqlbinlog' parses a `SET @@SQL_MODE = VALUE'
statement, the full VALUE, including `NO_DIR_IN_CREATE', is passed to
the receiving server.

The `storage_engine' system variable is not replicated, which is a good
thing for replication between different storage engines.

Session variables are not replicated properly when used in statements
that update tables. For example, `SET MAX_JOIN_SIZE=1000' followed by
`INSERT INTO mytable VALUES(@@MAX_JOIN_SIZE)' will not insert the same
data on the master and the slave. This does not apply to the common
sequence of `SET TIME_ZONE=...' followed by `INSERT INTO mytable
VALUES(CONVERT_TZ(...,...,@@time_zone))'.

Replication of session variables is not a problem when row-based
replication is being used. See *Note replication-formats::.


File: manual.info,  Node: replication-features-views,  Prev: replication-features-variables,  Up: replication-features

19.3.1.26 Replication and Views
...............................

Views are always replicated to slaves. Views are filtered by their own
name, not by the tables they refer to. This means that a view can be
replicated to the slave even if the view contains a table that would
normally be filtered out by `replication-ignore-table' rules. Care
should therefore be taken to ensure that views do not replicate table
data that would normally be filtered for security reasons.


File: manual.info,  Node: replication-compatibility,  Next: replication-upgrade,  Prev: replication-features,  Up: replication-notes

19.3.2 Replication Compatibility Between MySQL Versions
-------------------------------------------------------

The binary log format as implemented in MySQL 5.1 is considerably
different from that used in previous versions, especially with regard
to handling of character sets, `LOAD DATA INFILE', and time zones.

As a general rule, you should set up replication only between masters
and slaves running the same major versions (5.1, 5.0 or 4.1) of MySQL.
If you must execute replication between different major versions,
ensure that your client is at a version equal to or higher than that of
the master. For example, a master of 4.1.23 and a slave of 5.0.24
should work together.

We recommend using the most recent MySQL version available because
replication capabilities are continually being improved. We also
recommend using the same version for both the master and the slave. We
recommend upgrading masters and slaves running alpha or beta versions
to new (production) versions. In many cases, replication from a newer
master to an older slave will fail.

In general (but not always), slaves running MySQL 5.1.x can be used
with older masters, but not the reverse. However, there are known
issues with trying to replicate from a 4.0 or earlier master to a 5.1
or later slave (Bug#31240 (http://bugs.mysql.com/31240)).  For more
information on potential issues, see *Note replication-features::.

*Note*:

You _cannot_ replicate from a master that uses a newer binary log
format to a slave that uses an older format (for example, from MySQL
5.0 to MySQL 4.1.) This has significant implications for upgrading
replication servers, as described in *Note replication-upgrade::.

The preceding information pertains to replication compatibility at the
protocol level. However, there can be other constraints, such as
SQL-level compatibility issues. For example, a 5.1 master cannot
replicate to a 5.0 slave if the replicated statements use SQL features
available in 5.1 but not in 5.0. These and other issues are discussed
in *Note replication-features::.


File: manual.info,  Node: replication-upgrade,  Next: replication-faq,  Prev: replication-compatibility,  Up: replication-notes

19.3.3 Upgrading a Replication Setup
------------------------------------

When you upgrade servers that participate in a replication setup, the
procedure for upgrading depends on the current server versions and the
version to which you are upgrading.

This section applies to upgrading replication from MySQL 3.23, 4.0, or
4.1 to MySQL 5.1. A 4.0 server should be 4.0.3 or newer.

When you upgrade a master to 5.1 from an earlier MySQL release series,
you should first ensure that all the slaves of this master are using
the same 5.1.x release. If this is not the case, you should first
upgrade the slaves. To upgrade each slave, shut it down, upgrade it to
the appropriate 5.1.x version, restart it, and restart replication.
The 5.1 slave is able to read the old relay logs written prior to the
upgrade and to execute the statements they contain. Relay logs created
by the slave after the upgrade are in 5.1 format.

After the slaves have been upgraded, shut down the master, upgrade it
to the same 5.1.x release as the slaves, and restart it. The 5.1 master
is able to read the old binary logs written prior to the upgrade and to
send them to the 5.1 slaves. The slaves recognize the old format and
handle it properly. Binary logs created by the master following the
upgrade are in 5.1 format. These too are recognized by the 5.1 slaves.

In other words, there are no measures to take when upgrading to MySQL
5.1, except that the slaves must be MySQL 5.1 before you can upgrade
the master to 5.1. Note that downgrading from 5.1 to older versions
does not work so simply: You must ensure that any 5.1 binary logs or
relay logs have been fully processed, so that you can remove them
before proceeding with the downgrade.

Downgrading a replication setup to a previous version cannot be done
once you've switched from statement-based to row-based replication, and
after the first row-based statement has been written to the binlog. See
*Note replication-formats::.


File: manual.info,  Node: replication-faq,  Next: replication-problems,  Prev: replication-upgrade,  Up: replication-notes

19.3.4 Replication FAQ
----------------------

MySQL Enterprise

For expert advice on replication subscribe to the MySQL Enterprise
Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

*Questions*
   * 20.3.4.1: Does the slave need to be connected to the master all the
     time?

   * 20.3.4.2: Do I have to enable networking on my master to enable
     replication?

   * 20.3.4.3: How do I know how late a slave is compared to the
     master? In other words, how do I know the date of the last
     statement replicated by the slave?

   * 20.3.4.4: How do I force the master to block updates until the
     slave catches up?

   * 20.3.4.5: What issues should I be aware of when setting up two-way
     replication?

   * 20.3.4.6: 

     How can I use replication to improve performance of my system?

   * 20.3.4.7: What should I do to prepare client code in my own
     applications to use performance-enhancing replication?

   * 20.3.4.8: When and how much can MySQL replication improve the
     performance of my system?

   * 20.3.4.9: How can I use replication to provide redundancy or high
     availability?

   * 20.3.4.10: How do I tell whether a master server is using
     statement-based or row-based binary logging format?

   * 20.3.4.11: How do I tell a slave to use row-based replication?

   * 20.3.4.12: How do I prevent GRANT and REVOKE statements from
     replicating to slave machines?

   * 20.3.4.13: Does replication work on mixed operating systems (for
     example, the master runs on Linux while slaves run on Mac OS X and
     Windows)?

   * 20.3.4.14: Does replication work on mixed hardware architectures
     (for example, the master runs on a 64-bit machine while slaves run
     on 32-bit machines)?

*Questions and Answers* *20.3.4.1: ** Does the slave need to be
connected to the master all the time?  *

No, it does not. The slave can go down or stay disconnected for hours
or even days, and then reconnect and catch up on updates. For example,
you can set up a master/slave relationship over a dial-up link where
the link is up only sporadically and for short periods of time. The
implication of this is that, at any given time, the slave is not
guaranteed to be in sync with the master unless you take some special
measures.

To ensure that this is the case, you must not remove binary logs from
the master, where the information has not been replicated to the
slaves. Asynchronous replication can only work if the slave is able to
read the binary log from the last point in the binary logs where it had
read the replication statements.

*20.3.4.2: ** Do I have to enable networking on my master to enable
replication?  *

Networking must be enabled on the master. If networking is not enabled,
then the slave is unable to connect to the master and transfer the
binary log. Check that the `skip-networking' option has not been
enabled in your configuration file.

*20.3.4.3: ** How do I know how late a slave is compared to the master?
In other words, how do I know the date of the last statement replicated
by the slave?  *

You can read the `Seconds_Behind_Master' column in `SHOW SLAVE STATUS'.
See *Note replication-implementation-details::.

When the slave SQL thread executes an event read from the master, it
modifies its own time to the event timestamp.  (This is why `TIMESTAMP'
is well replicated.) In the `Time' column in the output of `SHOW
PROCESSLIST', the number of seconds displayed for the slave SQL thread
is the number of seconds between the timestamp of the last replicated
event and the real time of the slave machine. You can use this to
determine the date of the last replicated event. Note that if your
slave has been disconnected from the master for one hour, and then
reconnects, you may immediately see `Time' values like 3600 for the
slave SQL thread in `SHOW PROCESSLIST'. This is because the slave is
executing statements that are one hour old.

*20.3.4.4: ** How do I force the master to block updates until the slave
catches up?  *

Use the following procedure:

  1. On the master, execute these statements:

          mysql> FLUSH TABLES WITH READ LOCK;
          mysql> SHOW MASTER STATUS;

     Record the replication coordinates (the log filename and offset)
     from the output of the `SHOW' statement.

  2. On the slave, issue the following statement, where the arguments
     to the `MASTER_POS_WAIT()' function are the replication coordinate
     values obtained in the previous step:

          mysql> SELECT MASTER_POS_WAIT('LOG_NAME', LOG_OFFSET);

     The `SELECT' statement blocks until the slave reaches the
     specified log file and offset. At that point, the slave is in
     synchrony with the master and the statement returns.

  3. On the master, issue the following statement to allow the master
     to begin processing updates again:

          mysql> UNLOCK TABLES;

*20.3.4.5: ** What issues should I be aware of when setting up two-way
replication?  *

MySQL replication currently does not support any locking protocol
between master and slave to guarantee the atomicity of a distributed
(cross-server) update. In other words, it is possible for client A to
make an update to co-master 1, and in the meantime, before it
propagates to co-master 2, client B could make an update to co-master 2
that makes the update of client A work differently than it did on
co-master 1. Thus, when the update of client A makes it to co-master 2,
it produces tables that are different from what you have on co-master
1, even after all the updates from co-master 2 have also propagated.
This means that you should not chain two servers together in a two-way
replication relationship unless you are sure that your updates can
safely happen in any order, or unless you take care of mis-ordered
updates somehow in the client code.

You should also realize that two-way replication actually does not
improve performance very much (if at all) as far as updates are
concerned. Each server must do the same number of updates, just as you
would have a single server do. The only difference is that there is a
little less lock contention, because the updates originating on another
server are serialized in one slave thread. Even this benefit might be
offset by network delays.

*20.3.4.6: ** ** ** How can I use replication to improve performance of
my system?  *

You should set up one server as the master and direct all writes to it.
Then configure as many slaves as you have the budget and rackspace for,
and distribute the reads among the master and the slaves. You can also
start the slaves with the `--skip-innodb', `--low-priority-updates', and
`--delay-key-write=ALL' options to get speed improvements on the slave
end. In this case, the slave uses non-transactional `MyISAM' tables
instead of `InnoDB' tables to get more speed by eliminating
transactional overhead.

*20.3.4.7: ** What should I do to prepare client code in my own
applications to use performance-enhancing replication?  *

See the guide to using replication as a scale-out solution, *Note
replication-solutions-scaleout::.

*20.3.4.8: ** When and how much can MySQL replication improve the
performance of my system?  *

MySQL replication is most beneficial for a system that processes
frequent reads and infrequent writes. In theory, by using a
single-master/multiple-slave setup, you can scale the system by adding
more slaves until you either run out of network bandwidth, or your
update load grows to the point that the master cannot handle it.

To determine how many slaves you can use before the added benefits
begin to level out, and how much you can improve performance of your
site, you need to know your query patterns, and to determine
empirically by benchmarking the relationship between the throughput for
reads (reads per second, or `reads') and for writes (`writes') on a
typical master and a typical slave. The example here shows a rather
simplified calculation of what you can get with replication for a
hypothetical system.

Let's say that system load consists of 10% writes and 90% reads, and we
have determined by benchmarking that `reads' is 1200 - 2 x `writes'. In
other words, the system can do 1,200 reads per second with no writes,
the average write is twice as slow as the average read, and the
relationship is linear. Let us suppose that the master and each slave
have the same capacity, and that we have one master and N slaves. Then
we have for each server (master or slave):

`reads = 1200 - 2 x writes'

`reads = 9 x writes / (N + 1)' (reads are split, but writes go to all
servers)

`9 x writes / (N + 1) + 2 x writes = 1200'

`writes = 1200 / (2 + 9/(N+1))'

The last equation indicates the maximum number of writes for N slaves,
given a maximum possible read rate of 1,200 per minute and a ratio of
nine reads per write.

This analysis yields the following conclusions:

   * If N = 0 (which means we have no replication), our system can
     handle about 1200/11 = 109 writes per second.

   * If N = 1, we get up to 184 writes per second.

   * If N = 8, we get up to 400 writes per second.

   * If N = 17, we get up to 480 writes per second.

   * Eventually, as N approaches infinity (and our budget negative
     infinity), we can get very close to 600 writes per second,
     increasing system throughput about 5.5 times. However, with only
     eight servers, we increase it nearly four times.

Note that these computations assume infinite network bandwidth and
neglect several other factors that could be significant on your system.
In many cases, you may not be able to perform a computation similar to
the one just shown that accurately predicts what will happen on your
system if you add N replication slaves.  However, answering the
following questions should help you decide whether and by how much
replication will improve the performance of your system:

   * What is the read/write ratio on your system?

   * How much more write load can one server handle if you reduce the
     reads?

   * For how many slaves do you have bandwidth available on your
     network?

*20.3.4.9: ** How can I use replication to provide redundancy or high
availability?  *

How you implement redundancy is entirely dependent on your application
and circumstances. High-availability solutions (with automatic
failover) require active monitoring and either custom scripts or third
party tools to provide the failover support from the original MySQL
server to the slave.

To handle the process manually, you should be able to switch from a
failed master to a pre-configured slave by altering your application to
talk to the new server or by adjusting the DNS for the MySQL server
from the failed server to the new server.

For more information and some example solutions, see *Note
replication-solutions-switch::.

*20.3.4.10: ** How do I tell whether a master server is using
statement-based or row-based binary logging format?  *

Check the value of the `binlog_format' system variable:

     mysql> SHOW VARIABLES LIKE 'binlog_format';

The value will be either `STATEMENT' or `ROW'.

*20.3.4.11: ** How do I tell a slave to use row-based replication?  *

Slaves automatically know which format to use.

*20.3.4.12: ** How do I prevent GRANT and REVOKE statements from
replicating to slave machines?  *

Start the server with the `--replicate-wild-ignore-table=mysql.%'
option.

*20.3.4.13: ** Does replication work on mixed operating systems (for
example, the master runs on Linux while slaves run on Mac OS X and
Windows)?  *

Yes.

*20.3.4.14: ** Does replication work on mixed hardware architectures
(for example, the master runs on a 64-bit machine while slaves run on
32-bit machines)?  *

Yes.


File: manual.info,  Node: replication-problems,  Next: replication-bugs,  Prev: replication-faq,  Up: replication-notes

19.3.5 Troubleshooting Replication
----------------------------------

If you have followed the instructions, and your replication setup is
not working, the first thing to do is _check the error log for
messages_. Many users have lost time by not doing this soon enough
after encountering problems.

If you cannot tell from the error log what the problem was, try the
following techniques:

   * Verify that the master has binary logging enabled by issuing a
     `SHOW MASTER STATUS' statement. If logging is enabled, `Position'
     is non-zero. If binary logging is not enabled, verify that you are
     running the master with the `--log-bin' and `--server-id' options.

   * Verify that the slave is running. Use `SHOW SLAVE STATUS' to check
     whether the `Slave_IO_Running' and `Slave_SQL_Running' values are
     both `Yes'. If not, verify the options that were used when
     starting the slave server. For example, `--skip-slave-start'
     prevents the slave threads from starting until you issue a `START
     SLAVE' statement.

   * If the slave is running, check whether it established a connection
     to the master. Use `SHOW PROCESSLIST', find the I/O and SQL
     threads and check their `State' column to see what they display.
     See *Note replication-implementation-details::. If the I/O thread
     state says `Connecting to master', check the following:

        * Verify the privileges for the user being used for replication
          on the master.

        * Check that the hostname of the master is correct and that you
          are using the correct port to connect to the master.  The
          port used for replication is the same as used for client
          network communication (the default is `3306'). For the
          hostname, ensure that the name resolves to the correct IP
          address.

        * Check that networking on the master and slave have not been
          disabled. Look for the `skip-networking' option in the
          configuration file. It should either be commented out or
          deleted entirely.

        * If the master has a firewall or IP filtering configuration,
          ensure that the network port being used for MySQL is not
          being filtered.

        * Check that you can reach the master by using `ping' or
          `traceroute'/`tracert' to reach the host.

   * If the slave was running previously but has stopped, the reason
     usually is that some statement that succeeded on the master failed
     on the slave. This should never happen if you have taken a proper
     snapshot of the master, and never modified the data on the slave
     outside of the slave thread. If the slave stops unexpectedly, it
     is a bug or you have encountered one of the known replication
     limitations described in *Note replication-features::. If it is a
     bug, see *Note replication-bugs::, for instructions on how to
     report it.

   * If a statement that succeeded on the master refuses to run on the
     slave, try the following procedure if it is not feasible to do a
     full database resynchronization by deleting the slave's databases
     and copying a new snapshot from the master:

       1. Determine whether the affected table on the slave is
          different from the master table. Try to understand how this
          happened. Then make the slave's table identical to the
          master's and run `START SLAVE'.

       2. If the preceding step does not work or does not apply, try to
          understand whether it would be safe to make the update
          manually (if needed) and then ignore the next statement from
          the master.

       3. If you decide that you can skip the next statement from the
          master, issue the following statements:

               mysql> SET GLOBAL SQL_SLAVE_SKIP_COUNTER = N;
               mysql> START SLAVE;

          The value of N should be 1 if the next statement from the
          master does not use `AUTO_INCREMENT' or `LAST_INSERT_ID()'.
          Otherwise, the value should be 2. The reason for using a
          value of 2 for statements that use `AUTO_INCREMENT' or
          `LAST_INSERT_ID()' is that they take two events in the binary
          log of the master.

       4. If you are sure that the slave started out perfectly
          synchronized with the master, and that no one has updated the
          tables involved outside of the slave thread, then presumably
          the discrepancy is the result of a bug. If you are running
          the most recent version of MySQL, please report the problem.
          If you are running an older version, try upgrading to the
          latest production release to determine whether the problem
          persists.


File: manual.info,  Node: replication-bugs,  Prev: replication-problems,  Up: replication-notes

19.3.6 How to Report Replication Bugs or Problems
-------------------------------------------------

When you have determined that there is no user error involved, and
replication still either does not work at all or is unstable, it is
time to send us a bug report. We need to obtain as much information as
possible from you to be able to track down the bug.  Please spend some
time and effort in preparing a good bug report.

If you have a repeatable test case that demonstrates the bug, please
enter it into our bugs database using the instructions given in *Note
bug-reports::. If you have a `phantom' problem (one that you cannot
duplicate at will), use the following procedure:

  1. Verify that no user error is involved. For example, if you update
     the slave outside of the slave thread, the data goes out of
     synchrony, and you can have unique key violations on updates. In
     this case, the slave thread stops and waits for you to clean up
     the tables manually to bring them into synchrony. _This is not a
     replication problem. It is a problem of outside interference
     causing replication to fail._

  2. Run the slave with the `--log-slave-updates' and `--log-bin'
     options. These options cause the slave to log the updates that it
     receives from the master into its own binary logs.

  3. Save all evidence before resetting the replication state. If we
     have no information or only sketchy information, it becomes
     difficult or impossible for us to track down the problem. The
     evidence you should collect is:

        * All binary logs from the master

        * All binary logs from the slave

        * The output of `SHOW MASTER STATUS' from the master at the
          time you discovered the problem

        * The output of `SHOW SLAVE STATUS' from the slave at the time
          you discovered the problem

        * Error logs from the master and the slave

  4. Use `mysqlbinlog' to examine the binary logs.  The following
     should be helpful to find the problem statement.  LOG_POS and
     LOG_FILE are the `Master_Log_File' and `Read_Master_Log_Pos'
     values from `SHOW SLAVE STATUS'.

          shell> mysqlbinlog -j LOG_POS LOG_FILE | head

After you have collected the evidence for the problem, try to isolate
it as a separate test case first. Then enter the problem with as much
information as possible into our bugs database using the instructions
at *Note bug-reports::.


File: manual.info,  Node: replication-implementation,  Prev: replication-notes,  Up: replication

19.4 Replication Implementation
===============================

* Menu:

* replication-implementation-details::  Replication Implementation Details
* slave-logs::                   Replication Relay and Status Files
* replication-rules::            How Servers Evaluate Replication Rules

The basic mechanics of replication is based on the master server
keeping track of all changes to your databases (updates, deletes, and
so on) in its binary logs. The binary log serves as a written record of
each to the database from the moment the database was started. The
binary log contains records of all the statements which edit or modify
either the database structure or the data that the structure contains.
Typically `SELECT' statements are not recorded, as they do not modify
the database data or structure.

Each slave that connects to the master receives a copy of the binary
log, and executes the events within the binary log. This has the effect
of repeating the original statements and changes just as they were made
on the master. Tables are created or their structure modified, and data
is inserted, deleted and updated according to the statements that were
originally executed on the master.

Because each slave is independent, the replaying of the statements in
the masters binary log can occur on each slave that is connected to the
master. In addition, because each slave only receives a copy of the
binary log by requesting it from the master (it pulls the data from the
master, rather than the master pushing the data to the slave), the
slave is able to read and update the copy of the database at it's own
pace and rate and can start and stop the replication process at will
without affecting the master or the slaves ability to update to the
latest database status.

For more information on the specifics of the replication
implementation, see *Note replication-implementation-details::.

Slaves and masters report their status in respect of the replication
process regularly so that you can monitor the situation. For
information on slave states, see *Note slave-io-thread-states::, and
*Note slave-sql-thread-states::. For master states, see *Note
master-thread-states::.

The master binary log is written to a local relay log on the slave
before it is processed. The slave also records information about the
current position with the master's binary log and the local relayed
log. See *Note slave-logs::.

Databases and tables are updated on the slave according to a set of
rules that are applied according to the various configuration options
and variables that control statement evaluation. For details on how
these rules are applied, see *Note replication-rules::.


File: manual.info,  Node: replication-implementation-details,  Next: slave-logs,  Prev: replication-implementation,  Up: replication-implementation

19.4.1 Replication Implementation Details
-----------------------------------------

MySQL replication capabilities are implemented using three threads (one
on the master server and two on the slave). When a `START SLAVE'
statement is issued on a slave server, the slave creates an I/O thread,
which connects to the master and asks it to send the updates recorded
in its binary logs. The master creates a thread to send the binary log
contents to the slave. This thread can be identified as the `Binlog
Dump' thread in the output of `SHOW PROCESSLIST' on the master. The
slave I/O thread reads the updates that the master `Binlog Dump' thread
sends and copies them to local files, known as _relay logs_, in the
slave's data directory. The third thread is the SQL thread, which the
slave creates to read the relay logs and to execute the updates they
contain.

MySQL Enterprise

For constant monitoring of the status of slaves subscribe to the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

In the preceding description, there are three threads per master/slave
connection. A master that has multiple slaves creates one thread for
each currently-connected slave, and each slave has its own I/O and SQL
threads.

The slave uses two threads so that reading updates from the master and
executing them can be separated into two independent tasks.  Thus, the
task of reading statements is not slowed down if statement execution is
slow. For example, if the slave server has not been running for a
while, its I/O thread can quickly fetch all the binary log contents
from the master when the slave starts, even if the SQL thread lags far
behind. If the slave stops before the SQL thread has executed all the
fetched statements, the I/O thread has at least fetched everything so
that a safe copy of the statements is stored locally in the slave's
relay logs, ready for execution the next time that the slave starts.
This enables the master server to purge its binary logs sooner because
it no longer needs to wait for the slave to fetch their contents.

The `SHOW PROCESSLIST' statement provides information that tells you
what is happening on the master and on the slave regarding replication.
See *Note thread-information::, for descriptions of all
replicated-related states.

The following example illustrates how the three threads show up in the
output from `SHOW PROCESSLIST'.

On the master server, the output from `SHOW PROCESSLIST' looks like
this:

     mysql> SHOW PROCESSLIST\G
     *************************** 1. row ***************************
          Id: 2
        User: root
        Host: localhost:32931
          db: NULL
     Command: Binlog Dump
        Time: 94
       State: Has sent all binlog to slave; waiting for binlog to
              be updated
        Info: NULL

Here, thread 2 is a `Binlog Dump' replication thread for a connected
slave. The `State' information indicates that all outstanding updates
have been sent to the slave and that the master is waiting for more
updates to occur. If you see no `Binlog Dump' threads on a master
server, this means that replication is not running -- that is, that no
slaves are currently connected.

On the slave server, the output from `SHOW PROCESSLIST' looks like this:

     mysql> SHOW PROCESSLIST\G
     *************************** 1. row ***************************
          Id: 10
        User: system user
        Host:
          db: NULL
     Command: Connect
        Time: 11
       State: Waiting for master to send event
        Info: NULL
     *************************** 2. row ***************************
          Id: 11
        User: system user
        Host:
          db: NULL
     Command: Connect
        Time: 11
       State: Has read all relay log; waiting for the slave I/O
              thread to update it
        Info: NULL

This information indicates that thread 10 is the I/O thread that is
communicating with the master server, and thread 11 is the SQL thread
that is processing the updates stored in the relay logs. At the time
that the `SHOW PROCESSLIST' was run, both threads were idle, waiting
for further updates.

The value in the `Time' column can show how late the slave is compared
to the master. See *Note replication-faq::.


File: manual.info,  Node: slave-logs,  Next: replication-rules,  Prev: replication-implementation-details,  Up: replication-implementation

19.4.2 Replication Relay and Status Files
-----------------------------------------

* Menu:

* slave-logs-relaylog::          The Slave Relay Log
* slave-logs-status::            The Slave Status Files

During replication the MySQL server creates a number of files that are
used to hold the relayed binary log from the master, and record
information about the current status and location within the relayed
log. There are three file types used in the process:

   * The _relay log_ consists of the events read from the binary log of
     the master. Events in this binary log are executed on the slave as
     part of the replication thread.

   * The _master.info_ file contains the status and current
     configuration information for the slave's connectivity to the
     master. The file holds information on the master hostname, login
     credentials, and the current position within the master's binary
     log.

   * The _relay.info_ file holds the status information about the
     execution point within the slave's relay log files.

The relationship between the three files and the replication process is
as follows. The `master.info' file retains the point within the master
binary log that has been read from the master. These read events are
written to the relay log.  The `relay.info' file records the position
within the relay log of the statements that have been executed.


File: manual.info,  Node: slave-logs-relaylog,  Next: slave-logs-status,  Prev: slave-logs,  Up: slave-logs

19.4.2.1 The Slave Relay Log
............................

By default, relay logs filenames have the form
`HOST_NAME-relay-bin.NNNNNN', where HOST_NAME is the name of the slave
server host and NNNNNN is a sequence number. Successive relay log files
are created using successive sequence numbers, beginning with `000001'.
The slave uses an index file to track the relay log files currently in
use. The default relay log index filename is
`HOST_NAME-relay-bin.index'.  By default, the slave server creates
relay log files in its data directory.

The default filenames for relay logs and relay log index files can be
overridden with, respectively, the `--relay-log' and
`--relay-log-index' server options (see *Note replication-options::).
For this reason, changing a replication slave's hostname can cause
replication to fail with the errors `Failed to open the relay log' and
`Could not find target log during relay log initialization'. This is a
known issue which we intend to fix in a future MySQL release (see
Bug#2122 (http://bugs.mysql.com/2122)). If you anticipate that a
slave's hostname may change in the future (for example, if networking
is set up on the slave such that its hostname can be modified via
DHCP), then you can use these options to prevent this problem from
occurring. However, if you encounter this issue, one way to work around
it is to stop the slave server, prepend the contents of the old relay
log index file to the new one, then restart the slave. On a Unix
system, this can be done as shown here, where NEW_HOST_NAME is the new
hostname and OLD_HOST_NAME is the old one:

     shell< cat NEW_HOST_NAME-relay-bin.index >> OLD_HOST_NAME-relay-bin.index

     shell< mv OLD_HOST_NAME-relay-bin.index NEW_HOST_NAME-relay-bin.index

Relay logs have the same format as binary logs and can be read using
`mysqlbinlog'. The SQL thread automatically deletes each relay log file
as soon as it has executed all events in the file and no longer needs
it. There is no explicit mechanism for deleting relay logs because the
SQL thread takes care of doing so. However, `FLUSH LOGS' rotates relay
logs, which influences when the SQL thread deletes them.

A slave server creates a new relay log file under the following
conditions:

   * Each time the I/O thread starts.

   * When the logs are flushed; for example, with `FLUSH LOGS' or
     `mysqladmin flush-logs'.

   * When the size of the current relay log file becomes too large. The
     meaning of `too large' is determined as follows:

        * If the value of `max_relay_log_size' is greater than 0, that
          is the maximum relay log file size.

        * If the value of `max_relay_log_size' is 0, `max_binlog_size'
          determines the maximum relay log file size.


File: manual.info,  Node: slave-logs-status,  Prev: slave-logs-relaylog,  Up: slave-logs

19.4.2.2 The Slave Status Files
...............................

A slave replication server creates two small files in the data
directory. These _status files_ are named `master.info' and
`relay-log.info' by default. Their names can be changed by using the
`--master-info-file' and `--relay-log-info-file' options. See *Note
replication-options::.

The two status files contain information like that shown in the output
of the `SHOW SLAVE STATUS' statement, which is discussed in *Note
replication-slave-sql::.  Because the status files are stored on disk,
they survive a slave server's shutdown. The next time the slave starts
up, it reads the two files to determine how far it has proceeded in
reading binary logs from the master and in processing its own relay
logs.

The I/O thread updates the `master.info' file. The following table
shows the correspondence between the lines in the file and the columns
displayed by `SHOW SLAVE STATUS'.

*Line*      *Status Column*           *Description*
1                                     Number of lines in the file
2           `Master_Log_File'         The name of the master binary log
                                      currently being read from the
                                      master.
3           `Read_Master_Log_Pos'     The current position within the
                                      master binary log that have been
                                      read from the master.
4           `Master_Host'             The hostname of the master.
5           `Master_User'             The username used to connect to the
                                      master.
6           Password (not shown by    The password used to connect to the
            `SHOW SLAVE STATUS')      master.
7           `Master_Port'             The network port used to connect to
                                      the master.
8           `Connect_Retry'           The period (in seconds) that the
                                      slave will wait before trying to
                                      reconnect to the master.
9           `Master_SSL_Allowed'      Indicates whether the server
                                      supports SSL connections.
10          `Master_SSL_CA_File'      The file used for the Certificate
                                      Authority (CA) certificate.
11          `Master_SSL_CA_Path'      The path to the Certificate
                                      Authority (CA) certificates.
12          `Master_SSL_Cert'         The name of the SSL certificate
                                      file.
13          `Master_SSL_Cipher'       The name of the cipher in use for
                                      the SSL connection.
14          `Master_SSL_Key'          The name of the SSL key file.
15          `Master_SSL_Verify_Server_Cert'Whether to verify the server
                                      certificate.

`Master_SSL_Verify_Server_Cert' is present in `master.info' as of MySQL
5.1.18. It is used as described for the `--ssl-verify-server-cert'
option in *Note ssl-options::.

The SQL thread updates the `relay-log.info' file. The following table
shows the correspondence between the lines in the file and the columns
displayed by `SHOW SLAVE STATUS'.

*Line*      *Status Column*           *Description*
1           `Relay_Log_File'          The name of the current relay log
                                      file.
2           `Relay_Log_Pos'           The current position within the
                                      relay log file. Events up to this
                                      position have been executed on the
                                      slave database.
3           `Relay_Master_Log_File'   The name of the master binary log
                                      file from which the events in the
                                      relay log file were read.
4           `Exec_Master_Log_Pos'     The equivalent position within the
                                      master's binary log file of events
                                      that have already been executed.

The contents of the `relay-log.info' file and the states shown by the
`SHOW SLAVE STATES' command may not match if the `relay-log.info' file
has not been flushed to disk. Ideally, you should only view
`relay-log.info' on a slave that is offline (i.e. `mysqld' is not
running). For a running system, `SHOW SLAVE STATUS' should be used.


File: manual.info,  Node: replication-rules,  Prev: slave-logs,  Up: replication-implementation

19.4.3 How Servers Evaluate Replication Rules
---------------------------------------------

If a master server does not write a statement to its binary log, the
statement is not replicated. If the server does log the statement, the
statement is sent to all slaves and each slave determines whether to
execute it or ignore it.

On the master you can control which databases write events to the
binary log using the `--binlog-do-db' and `--binlog-ignore-db' options
to control binary logging. For a description of the rules that servers
use in evaluating these options, see *Note binary-log::. You should not
use these options to control the databases and tables that are
replicated, instead, use filtering on the slave to control the events
that are executed on the slave.

On the slave side, decisions about whether to execute or ignore
statements received from the master are made according to the
`--replicate-*' options that the slave was started with. (See *Note
replication-options::.) The slave evaluates these options using the
following procedure, which first checks the database-level options and
then the table-level options.

In the simplest case, when there are no `--replicate-*' options, the
procedure yields the result that the slave executes all statements that
it receives from the master. Otherwise, the result depends on the
particular options given. In general, to make it easier to determine
what effect an option set will have, it is recommended that you avoid
mixing `do' and `ignore' options, or wildcard and non-wildcard options.

*Stage 1. Check the database options.*

At this stage, the slave checks whether there are any
`--replicate-do-db' or `--replicate-ignore-db' options that specify
database-specific conditions:

   * _No_: Permit the statement and proceed to the table-checking stage.

   * _Yes_: Test the options using the same rules as for the
     `--binlog-do-db' and `--binlog-ignore-db' options to determine
     whether to permit or ignore the statement. What is the result of
     the test?

        * _Permit_: Do not execute the statement immediately. Defer the
          decision and proceed to the table-checking stage.

        * _Ignore_: Ignore the statement and exit.

This stage can permit a statement for further option-checking, or cause
it to be ignored. However, statements that are permitted at this stage
are not actually executed yet. Instead, they pass to the following
stage that checks the table options.

*Stage 2. Check the table options.*

First, as a preliminary condition, the slave checks whether
statement-based replication is enabled. If so and the statement occurs
within a stored function, execute the statement and exit.  (If
row-based replication is enabled, the slave does not know whether a
statement occurred within a stored function on the master, so this
condition does not apply.)

Next, the slave checks for table options and evaluates them. If the
server reaches this point, it executes all statements if there are no
table options. If there are `do' table options, the statement must
match one of them if it is to be executed; otherwise, it is ignored. If
there are any `ignore' options, all statements are executed except
those that match any `ignore' option. The following steps describe how
this evaluation occurs in more detail.

  1. Are there any `--replicate-*-table' options?

        * _No_: There are no table restrictions, so all statements
          match. Execute the statement and exit.

        * _Yes_: There are table restrictions.  Evaluate the tables to
          be updated against them. There might be multiple tables to
          update, so loop through the following steps for each table
          looking for a matching option. In this case, the behavior
          depends on whether statement-based replication or row-based
          replication is enabled:

             * _Statement-based replication_: Proceed to the next step
               and begin evaluating the table options in the order
               shown (first the non-wild options, and then the wild
               options). Only tables that are to be updated are
               compared to the options. For example, if the statement
               is `INSERT INTO sales SELECT * FROM prices', only
               `sales' is compared to the options).  If several tables
               are to be updated (multiple-table statement), the first
               table that matches `do' or `ignore' wins. That is, the
               server checks the first table against the options. If no
               decision could be made, it checks the second table
               against the options, and so on.

             * _Row-based replication_: All table row changes are
               filtered individually. For multiple-table updates, each
               table is filtered separately according to the options.
               Some updates may be executed and some not, depending on
               the options and the changes to be made. Row-based
               replication correctly handles cases that would not
               replicate correctly with statement-based replication, as
               in this example which assumes that tables in the `foo'
               database should be replicated:

                    mysql> USE bar;
                    mysql> INSERT INTO foo.sometable VALUES (1);

  2. Are there any `--replicate-do-table' options?

        * _No_: Proceed to the next step.

        * _Yes_: Does the table match any of them?

             * _No_: Proceed to the next step.

             * _Yes_: Execute the statement and exit.

  3. Are there any `--replicate-ignore-table' options?

        * _No_: Proceed to the next step.

        * _Yes_: Does the table match any of them?

             * _No_: Proceed to the next step.

             * _Yes_: Ignore the statement and exit.

  4. Are there any `--replicate-wild-do-table' options?

        * _No_: Proceed to the next step.

        * _Yes_: Does the table match any of them?

             * _No_: Proceed to the next step.

             * _Yes_: Execute the statement and exit.

  5. Are there any `--replicate-wild-ignore-table' options?

        * _No_: Proceed to the next step.

        * _Yes_: Does the table match any of them?

             * _No_: Proceed to the next step.

             * _Yes_: Ignore the statement and exit.

  6. No `--replicate-*-table' option was matched. Is there another
     table to test against these options?

        * _No_: We have now tested all tables to be updated and could
          not match any option. Are there `--replicate-do-table' or
          `--replicate-wild-do-table' options?

             * _No_: There were no `do' table options, so no explicit
               `do' match is required. Execute the statement and exit.

             * _Yes_: There were `do' table options, so the statement
               is executed only with an explicit match to one of them.
               Ignore the statement and exit.

        * _Yes_: Loop.

Examples:

   * No `--replicate-*' options at all

     The slave executes all statements that it receives from the master.

   * `--replicate-*-db' options, but no table options

     The slave permits or ignores statements using the database
     options. Then it executes all statements permitted by those
     options because there are no table restrictions.

   * `--replicate-*-table' options, but no database options

     All statements are permitted at the database-checking stage
     because there are no database conditions. The slave executes or
     ignores statements based on the table options.

   * A mix of database and table options

     The slave permits or ignores statements using the database
     options. Then it evaluates all statements permitted by those
     options according to the table options. In some cases, this
     process can yield what might seem a counterintuitive result.
     Consider the following set of options:

          [mysqld]
          replicate-do-db    = db1
          replicate-do-table = db2.mytbl2

     Suppose that `db1' is the default database and the slave receives
     this statement:

          INSERT INTO mytbl1 VALUES(1,2,3);

     The database is `db1', which matches the `--replicate-do-db'
     option at the database-checking stage. The algorithm then proceeds
     to the table-checking stage. If there were no table options, the
     statement would be executed. However, because the options include
     a `do' table option, the statement must match if it is to be
     executed. The statement does not match, so it is ignored. (The
     same would happen for any table in `db1'.)


File: manual.info,  Node: mysql-cluster,  Next: partitioning,  Prev: replication,  Up: Top

20 MySQL Cluster
****************

* Menu:

* mysql-cluster-overview::       MySQL Cluster Overview
* mysql-cluster-multi-computer::  Simple Multi-Computer How-To
* mysql-cluster-configuration::  MySQL Cluster Configuration
* mysql-cluster-options-variables::  MySQL Cluster Options and Variables
* mysql-cluster-upgrade-downgrade::  Upgrading and Downgrading MySQL Cluster
* mysql-cluster-process-management::  Process Management in MySQL Cluster
* mysql-cluster-management::     Management of MySQL Cluster
* mysql-cluster-security::       MySQL Cluster Security Issues
* mysql-cluster-backup::         On-line Backup of MySQL Cluster
* mysql-cluster-utilities::      Cluster Utility Programs
* mysql-cluster-replication::    MySQL Cluster Replication
* mysql-cluster-disk-data::      MySQL Cluster Disk Data Tables
* mysql-cluster-interconnects::  Using High-Speed Interconnects with MySQL Cluster
* mysql-cluster-limitations::    Known Limitations of MySQL Cluster
* mysql-cluster-roadmap::        MySQL Cluster Development Roadmap
* mysql-cluster-glossary::       MySQL Cluster Glossary
* mysql-cluster-news::           Changes in MySQL Cluster 6.x

This chapter contains information about _MySQL Cluster_, which is a
high-availability, high-redundancy version of MySQL adapted for the
distributed computing environment, using the `NDB' (also known as
`NDBCLUSTER') storage engine to enable running several MySQL servers in
a cluster.

This storage engine is available in MySQL 5.1 binary releases through
MySQL 5.1.23, including RPMs compatible with most modern Linux
distributions. Beginning with MySQL 5.1.24, standard MySQL server
binaries built by MySQL no longer provide support for the `NDBCLUSTER'
storage engine. Instead, users of MySQL Cluster binaries built by MySQL
should upgrade to MySQL Cluster NDB 6.2.15 (or a later MySQL Cluster
release) which includes binary releases for supported platforms,
including RPMs that should work with most Linux distributions. MySQL
Cluster users who build from source should be aware that, also
beginning with MySQL 5.1.24, `NDBCLUSTER' sources in the standard MySQL
5.1 tree are no longer maintained; these users should upgrade using the
MySQL Cluster NDB 6.2.15, 6.3.16, or a later MySQL Cluster NDB 6.2 or
6.3 source release.

*Note*:

MySQL Cluster NDB 6.1, 6.2, and 6.3 were formerly known as `MySQL
Cluster Carrier Grade Edition'. Beginning with MySQL Cluster NDB 6.2.15
and MySQL Cluster NDB 6.3.14, this term is no longer applied to the
MySQL Cluster software -- which is now known simply as `MySQL Cluster'
-- but rather to a commercial licensing and support package. You can
learn more about available options for commerical licensing of MySQL
Cluster from `MySQL Cluster Features
(http://mysql.com/products/database/cluster/features.html)', on the
MySQL web site.

This chapter contains information about MySQL Cluster in MySQL 5.1
mainline releases through MySQL 5.1.23, MySQL Cluster NDB 6.2 releases
through 5.1.24-ndb-6.2.16, and MySQL Cluster NDB 6.3 releases through
5.1.24-ndb-6.3.17. It also contains historical information about the
MySQL Cluster NDB 6.1 series, although this series is no longer in
active development.

Platforms supported

MySQL Cluster is currently available and supported on a number of
platforms, including Linux, Solaris, Mac OS X, HP-UX, and other
Unix-style operating systems on a variety of hardware. For exact levels
of support available for on specific combinations of operating system
versions, operating system distributions, and hardware platforms,
please refer to the `Cluster Supported Platforms list
(http://www.mysql.com/support/supportedplatforms/cluster.html)',
maintained by the MySQL Support Team on the MySQL web site.

*Important*:

MySQL Cluster is _not_ currently supported on Microsoft Windows. We are
working to make Cluster available on all operating systems supported by
MySQL, including Windows, and will update the information provided here
as this work continues.

Availability

MySQL Cluster NDB 6.2 binary and source packages are available for
supported platforms from `http://dev.mysql.com/downloads/cluster'.

*Note*:

Binary releases and RPMs are not available for MySQL Cluster NDB 6.2
prior to MySQL Cluster NDB 6.2.15.

MySQL Cluster NDB 6.3 is currently available only as source.  Source
tarballs for the latest MySQL Cluster NDB 6.3 release can be obtained
from `ftp://ftp.mysql.com/pub/mysql/download/cluster_telco/'.

MySQL Cluster versioning

Starting with MySQL Cluster NDB 6.1 and 6.2, MySQL Cluster follows a
somewhat different release pattern from the mainline MySQL 5.1 Cluster
series of releases. Each MySQL Cluster release is identified by a
two-part version string, which is displayed by `SELECT VERSION()' in the
`mysql' client, as shown here:

     shell> mysql
     Welcome to the MySQL monitor.  Commands end with ; or \g.
     Your MySQL connection id is 2
     Server version: 5.1.24-ndb-6.2.16-debug Source distribution

     Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

     mysql> SELECT VERSION();
     +-------------------------+
     | VERSION()               |
     +-------------------------+
     | 5.1.24-ndb-6.2.16-debug |
     +-------------------------+
     1 row in set (0.00 sec)

This version string is also displayed in the output from the `ndb_mgm'
client's `SHOW' command:

     ndb_mgm> SHOW
     Connected to Management Server at: localhost:1186
     Cluster Configuration
     ---------------------
     [ndbd(NDB)]     2 node(s)
     id=1    @10.0.10.6  (mysql-5.1.24 ndb-6.2.15, Nodegroup: 0, Master)
     id=2    @10.0.10.8  (mysql-5.1.24 ndb-6.2.15, Nodegroup: 0)

     [ndb_mgmd(MGM)] 1 node(s)
     id=3    @10.0.10.2  (mysql-5.1.24 ndb-6.2.15)

     [mysqld(API)]   2 node(s)
     id=4    @10.0.10.10  (mysql-5.1.24 ndb-6.2.15)
     id=5 (not connected, accepting connect from any host)

The version string identifies the mainline MySQL version from which the
MySQL Cluster release was branched and the version of the `NDB' storage
engine used. For example, the full version string for MySQL Cluster NDB
6.1.15 (the first MySQL Cluster NDB 6.2 binary release, as shown in the
preceding examples) is `mysql-5.1.24 ndb-6.2.15'. From this we can
determine the following information:

   * The portion of the version string preceding `ndb' is the MySQL
     Server base version.  This means that MySQL Cluster NDB 6.2.15
     derives from the MySQL 5.1.24, and contains all feature
     enhancement and bugfixes from MySQL 5.1 up to and including MySQL
     5.1.24.

   * The portion of the version string following `ndb-' represents the
     version number of the `NDB' (or `NDBCLUSTER') storage engine.
     MySQL Cluster NDB 6.2.15 uses version 6.2.15 of the `NDB' storage
     engine.

MySQL Cluster development source trees

MySQL Cluster development trees can also be accessed via
`https://code.launchpad.net/~mysql/':

   * `MySQL Cluster NDB 6.1
     (https://code.launchpad.net/~mysql/mysql-server/mysql-5.1-telco-6.1)'

   * `MySQL Cluster NDB 6.2
     (https://code.launchpad.net/~mysql/mysql-server/mysql-5.1-telco-6.2)'

   * `MySQL Cluster NDB 6.3
     (https://code.launchpad.net/~mysql/mysql-server/mysql-5.1-telco-6.2)'

The MySQL Cluster development sources maintained at
`https://code.launchpad.net/~mysql/' are GPL-licensed. For information
about obtaining MySQL sources using Bazaar and building them yourself,
see *Note installing-source-tree::.

Currently, MySQL Cluster NDB 6.2 and MySQL Cluster NDB 6.3 are both
under active development, with the 6.2 series now available in source
and binary format and 6.3 as source only. MySQL Cluster NDB 6.4 is
beginning to be developed internally and is intended for testing
purposes. MySQL Cluster NDB 6.1 is no longer in active development. For
an overview of major features added in MySQL Cluster, see *Note
mysql-cluster-roadmap::.

This chapter represents a work in progress, and its contents are
subject to revision as MySQL Cluster continues to evolve. Additional
information regarding MySQL Cluster can be found on the MySQL AB Web
site at `http://www.mysql.com/products/cluster/'.

Additional resources

More information may be found in the following places:

   * Answers to some commonly asked questions about Cluster may be
     found in the *Note faqs-mysql-cluster::.

   * The MySQL Cluster mailing list: `http://lists.mysql.com/cluster'.

   * The MySQL Cluster Forum: `http://forums.mysql.com/list.php?25'.

   * Many MySQL Cluster users and some of the MySQL Cluster developers
     blog about their experiences with Cluster, and make feeds of these
     available through PlanetMySQL (http://www.planetmysql.org/).

   * If you are new to MySQL Cluster, you may find our Developer Zone
     article `How to set up a MySQL Cluster for two servers
     (http://dev.mysql.com/tech-resources/articles/mysql-cluster-for-two-servers.html)'
     to be helpful.


File: manual.info,  Node: mysql-cluster-overview,  Next: mysql-cluster-multi-computer,  Prev: mysql-cluster,  Up: mysql-cluster

20.1 MySQL Cluster Overview
===========================

* Menu:

* mysql-cluster-basics::         MySQL Cluster Core Concepts
* mysql-cluster-nodes-groups::   MySQL Cluster Nodes, Node Groups, Replicas, and Partitions

_MySQL Cluster_ is a technology that enables clustering of in-memory
databases in a shared-nothing system. The shared-nothing architecture
allows the system to work with very inexpensive hardware, and with a
minimum of specific requirements for hardware or software.

MySQL Cluster is designed not to have any single point of failure.  For
this reason, each component is expected to have its own memory and
disk, and the use of shared storage mechanisms such as network shares,
network filesystems, and SANs is not recommended or supported.

MySQL Cluster integrates the standard MySQL server with an in-memory
clustered storage engine called `NDB'. In our documentation, the term
`NDB' refers to the part of the setup that is specific to the storage
engine, whereas `MySQL Cluster' refers to the combination of MySQL and
the `NDB' storage engine.

A MySQL Cluster consists of a set of computers, each running one or
more processes which may include a MySQL server, a data node, a
management server, and (possibly) specialized data access programs.
The relationship of these components in a cluster is shown here:

MySQL Cluster Components

All these programs work together to form a MySQL Cluster. When data is
stored in the `NDBCLUSTER' storage engine, the tables are stored in the
data nodes. Such tables are directly accessible from all other MySQL
servers in the cluster. Thus, in a payroll application storing data in
a cluster, if one application updates the salary of an employee, all
other MySQL servers that query this data can see this change
immediately.

The data stored in the data nodes for MySQL Cluster can be mirrored;
the cluster can handle failures of individual data nodes with no other
impact than that a small number of transactions are aborted due to
losing the transaction state. Because transactional applications are
expected to handle transaction failure, this should not be a source of
problems.


File: manual.info,  Node: mysql-cluster-basics,  Next: mysql-cluster-nodes-groups,  Prev: mysql-cluster-overview,  Up: mysql-cluster-overview

20.1.1 MySQL Cluster Core Concepts
----------------------------------

_`NDB'_ is an in-memory storage engine offering high-availability and
data-persistence features.

The `NDB' storage engine can be configured with a range of failover and
load-balancing options, but it is easiest to start with the storage
engine at the cluster level. MySQL Cluster's `NDB' storage engine
contains a complete set of data, dependent only on other data within the
cluster itself.

The cluster portion of MySQL Cluster is currently configured
independently of the MySQL servers. In a MySQL Cluster, each part of
the cluster is considered to be a _node_.

*Note*:

In many contexts, the term `node' is used to indicate a computer, but
when discussing MySQL Cluster it means a _process_. It is possible to
run any number of nodes on a single computer, for which we use the term
_cluster host_.

(However, it should be noted MySQL does not currently support the use
of multiple data nodes on a single computer in a production setting. See
*Note mysql-cluster-limitations-multiple-nodes::.)

There are three types of cluster nodes, and in a minimal MySQL Cluster
configuration, there will be at least three nodes, one of each of these
types:

   * _Management node_ (MGM node): The role of this type of node is to
     manage the other nodes within the MySQL Cluster, performing such
     functions as providing configuration data, starting and stopping
     nodes, running backup, and so forth. Because this node type
     manages the configuration of the other nodes, a node of this type
     should be started first, before any other node. An MGM node is
     started with the command `ndb_mgmd'.

   * _Data node_: This type of node stores cluster data. There are as
     many data nodes as there are replicas, times the number of
     fragments. For example, with two replicas, each having two
     fragments, you will need four data nodes. It is not necessary to
     have more than one replica. A data node is started with the
     command `ndbd'.

   * _SQL node_: This is a node that accesses the cluster data. In the
     case of MySQL Cluster, an SQL node is a traditional MySQL server
     that uses the `NDB Cluster' storage engine. An SQL node is
     typically started with the command `mysqld --ndbcluster' or by
     using `mysqld' with the `ndbcluster' option added to `my.cnf'.

     An SQL node is actually just a specialised type of _API node_,
     which designates any application which accesses Cluster data. One
     example of an API node is the `ndb_restore' utility that is used
     to restore a cluster backup. It is possible to write such
     applications using the NDB API
     (http://dev.mysql.com/doc/ndbapi/en/index.html).

*Important*:

It is not realistic to expect to employ a three-node setup in a
production environment. Such a configuration provides no redundancy; in
order to benefit from MySQL Cluster's high-availability features, you
must use multiple data and SQL nodes. The use of multiple management
nodes is also highly recommended.

For a brief introduction to the relationships between nodes, node
groups, replicas, and partitions in MySQL Cluster, see *Note
mysql-cluster-nodes-groups::.

Configuration of a cluster involves configuring each individual node in
the cluster and setting up individual communication links between
nodes. MySQL Cluster is currently designed with the intention that data
nodes are homogeneous in terms of processor power, memory space, and
bandwidth. In addition, to provide a single point of configuration, all
configuration data for the cluster as a whole is located in one
configuration file.

The management server (MGM node) manages the cluster configuration file
and the cluster log. Each node in the cluster retrieves the
configuration data from the management server, and so requires a way to
determine where the management server resides. When interesting events
occur in the data nodes, the nodes transfer information about these
events to the management server, which then writes the information to
the cluster log.

In addition, there can be any number of cluster client processes or
applications. These are of two types:

   * Standard MySQL clients

     These are no different for MySQL Cluster than they are for
     standard (non-Cluster) MySQL. In other words, MySQL Cluster can be
     accessed from existing MySQL applications written in PHP, Perl, C,
     C++, Java, Python, Ruby, and so on.

   * Management clients

     These clients connect to the management server and provide
     commands for starting and stopping nodes gracefully, starting and
     stopping message tracing (debug versions only), showing node
     versions and status, starting and stopping backups, and so on.


File: manual.info,  Node: mysql-cluster-nodes-groups,  Prev: mysql-cluster-basics,  Up: mysql-cluster-overview

20.1.2 MySQL Cluster Nodes, Node Groups, Replicas, and Partitions
-----------------------------------------------------------------

This section discusses the manner in which MySQL Cluster divides and
duplicates data for storage.

Central to an understanding of this topic are the following concepts,
listed here with brief definitions:

   * (Data) Node

     An `ndbd' process, which stores a _replica_ --that is, a copy of
     the _partition_ (see below) assigned to the node group of which
     the node is a member.

     Each data node should be located on a separate computer. While it
     is also possible to host multiple `ndbd' processes on a single
     computer, such a configuration is not supported.

     It is common for the terms `node' and `data node' to be used
     interchangeably when referring to an `ndbd' process; where
     mentioned, management (MGM) nodes (`ndb_mgmd' processes) and SQL
     nodes (`mysqld' processes) are specified as such in this
     discussion.

   * Node Group

     A node group consists of one or more nodes, and stores partitions,
     or sets of _replicas_ (see next item).

     *Note*:

     All node groups in a cluster must have the same number of nodes.

   * Partition

     This is a portion of the data stored by the cluster. There are as
     many cluster partitions as nodes participating in the cluster.
     Each node is responsible for keeping at least one copy of any
     partitions assigned to it (that is, at least one replica)
     available to the cluster.

     A replica belongs entirely to a single node; a node can (and
     usually does) store several replicas.

   * Replica

     This is a copy of a cluster partition. Each node in a node group
     stores a replica. Also sometimes known as a _partition replica_.
     The number of replicas is equal to the number of nodes per node
     group.

The following diagram illustrates a MySQL Cluster with four data nodes,
arranged in two node groups of two nodes each; nodes 1 and 2 belong to
node group 0, and nodes 3 and 4 belong to node group 1. Note that only
data (`ndbd') nodes are shown here; although a working cluster requires
an `ndb_mgm' process for cluster management and at least one SQL node
to access the data stored by the cluster, these have been omitted in
the figure for clarity.

A MySQL Cluster, with 2 node groups having 2 nodes each

The data stored by the cluster is divided into four partitions,
numbered 0, 1, 2, and 3. Each partition is stored -- in multiple copies
-- on the same node group. Partitions are stored on alternate node
groups:

   * Partition 0 is stored on node group 0; a _primary replica_
     (primary copy) is stored on node 1, and a _backup replica_ (backup
     copy of the partition) is stored on node 2.

   * Partition 1 is stored on the other node group (node group 1); this
     partition's primary replica is on node 3, and its backup replica
     is on node 4.

   * Partition 2 is stored on node group 0. However, the placing of its
     two replicas is reversed from that of Partition 0; for Partition
     2, the primary replica is stored on node 2, and the backup on node
     1.

   * Partition 3 is stored on node group 1, and the placement of its
     two replicas are reversed from those of partition 1. That is, its
     primary replica is located on node 4, with the backup on node 3.

What this means regarding the continued operation of a MySQL Cluster is
this: so long as each node group participating in the cluster has at
least one node operating, the cluster has a complete copy of all data
and remains viable. This is illustrated in the next diagram.

Nodes required to keep a 2x2 cluster viable

In this example, where the cluster consists of two node groups of two
nodes each, any combination of at least one node in node group 0 and at
least one node in node group 1 is sufficient to keep the cluster
`alive' (indicated by arrows in the diagram).  However, if _both_ nodes
from _either_ node group fail, the remaining two nodes are not
sufficient (shown by the arrows marked out with an *X*); in either
case, the cluster has lost an entire partition and so can no longer
provide access to a complete set of all cluster data.


File: manual.info,  Node: mysql-cluster-multi-computer,  Next: mysql-cluster-configuration,  Prev: mysql-cluster-overview,  Up: mysql-cluster

20.2 Simple Multi-Computer How-To
=================================

* Menu:

* mysql-cluster-multi-hardware-software-network::  Hardware, Software, and Networking
* mysql-cluster-multi-install::  Multi-Computer Installation
* mysql-cluster-multi-config::   Multi-Computer Configuration
* mysql-cluster-multi-initial::  Initial Startup
* mysql-cluster-multi-load-data-queries::  Loading Sample Data and Performing Queries
* mysql-cluster-multi-shutdown-restart::  Safe Shutdown and Restart

This section is a `How-To' that describes the basics for how to plan,
install, configure, and run a MySQL Cluster.  Whereas the examples in
*Note mysql-cluster-configuration:: provide more in-depth information
on a variety of clustering options and configuration, the result of
following the guidelines and procedures outlined here should be a
usable MySQL Cluster which meets the _minimum_ requirements for
availability and safeguarding of data.

This section covers hardware and software requirements; networking
issues; installation of MySQL Cluster; configuration issues; starting,
stopping, and restarting the cluster; loading of a sample database; and
performing queries.

Basic assumptions

This `How-To' makes the following assumptions:

  1. The cluster is to be set up with four nodes, each on a separate
     host, and each with a fixed network address on a typical Ethernet
     network as shown here:

     *Node*                             *IP Address*
     Management (MGM) node              192.168.0.10
     MySQL server (SQL) node            192.168.0.20
     Data (NDBD) node "A"               192.168.0.30
     Data (NDBD) node "B"               192.168.0.40

     This may be made clearer in the following diagram:

     MySQL Cluster Multi-Computer Setup

     In the interest of simplicity (and reliability), this `How-To'
     uses only numeric IP addresses.  However, if DNS resolution is
     available on your network, it is possible to use hostnames in lieu
     of IP addresses in configuring Cluster. Alternatively, you can use
     the `/etc/hosts' file or your operating system's equivalent for
     providing a means to do host lookup if such is available.

     *Note*:

     A common problem when trying to use hostnames for Cluster nodes
     arises because of the way in which some operating systems
     (including some Linux distributions) set up the system's own
     hostname in the `/etc/hosts' during installation. Consider two
     machines with the hostnames `ndb1' and `ndb2', both in the
     `cluster' network domain. Red Hat Linux (including some
     derivatives such as CentOS and Fedora) places the following
     entries in these machines' `/etc/hosts' files:

          #  ndb1 `/etc/hosts':
          127.0.0.1   ndb1.cluster ndb1 localhost.localdomain localhost

          #  ndb2 `/etc/hosts':
          127.0.0.1   ndb2.cluster ndb2 localhost.localdomain localhost

     SUSE Linux (including OpenSUSE) places these entries in the
     machines' `/etc/hosts' files:

          #  ndb1 `/etc/hosts':
          127.0.0.1       localhost
          127.0.0.2       ndb1.cluster ndb1

          #  ndb2 `/etc/hosts':
          127.0.0.1       localhost
          127.0.0.2       ndb2.cluster ndb2

     In both instances, `ndb1' routes `ndb1.cluster' to a loopback IP
     address, but gets a public IP address from DNS for `ndb2.cluster',
     while `ndb2' routes `ndb2.cluster' to a loopback address and
     obtains a public address for `ndb1.cluster'. The result is that
     each data node connects to the management server, but cannot tell
     when any other data nodes have connected, and so the data nodes
     appear to hang while starting.

     You should also be aware that you cannot mix `localhost' and other
     hostnames or IP addresses in `config.ini'. For these reasons, the
     solution in such cases (other than to use IP addresses for _all_
     `config.ini' `HostName' entries) is to remove the fully qualified
     hostnames from `/etc/hosts' and use these in `config.ini' for all
     cluster hosts.

  2. Each host in our scenario is an Intel-based desktop PC running a
     common, generic Linux distribution installed to disk in a standard
     configuration, and running no unnecessary services. The core OS
     with standard TCP/IP networking capabilities should be sufficient.
     Also for the sake of simplicity, we also assume that the
     filesystems on all hosts are set up identically. In the event that
     they are not, you will need to adapt these instructions
     accordingly.

  3. Standard 100 Mbps or 1 gigabit Ethernet cards are installed on
     each machine, along with the proper drivers for the cards, and
     that all four hosts are connected via a standard-issue Ethernet
     networking appliance such as a switch. (All machines should use
     network cards with the same throughout. That is, all four machines
     in the cluster should have 100 Mbps cards _or_ all four machines
     should have 1 Gbps cards.) MySQL Cluster will work in a 100 Mbps
     network; however, gigabit Ethernet will provide better performance.

     Note that MySQL Cluster is _not_ intended for use in a network for
     which throughput is less than 100 Mbps. For this reason (among
     others), attempting to run a MySQL Cluster over a public network
     such as the Internet is not likely to be successful, and is not
     recommended.

  4. For our sample data, we will use the `world' database which is
     available for download from the MySQL AB Web site. As this
     database takes up a relatively small amount of space, we assume
     that each machine has 256MB RAM, which should be sufficient for
     running the operating system, host NDB process, and (for the data
     nodes) for storing the database.

Although we refer to a Linux operating system in this How-To, the
instructions and procedures that we provide here should be easily
adaptable to other supported operating systems. We also assume that you
already know how to perform a minimal installation and configuration of
the operating system with networking capability, or that you are able
to obtain assistance in this elsewhere if needed.

We discuss MySQL Cluster hardware, software, and networking
requirements in somewhat greater detail in the next section. (See *Note
mysql-cluster-multi-hardware-software-network::.)


File: manual.info,  Node: mysql-cluster-multi-hardware-software-network,  Next: mysql-cluster-multi-install,  Prev: mysql-cluster-multi-computer,  Up: mysql-cluster-multi-computer

20.2.1 Hardware, Software, and Networking
-----------------------------------------

One of the strengths of MySQL Cluster is that it can be run on
commodity hardware and has no unusual requirements in this regard,
other than for large amounts of RAM, due to the fact that all live data
storage is done in memory. (It is possible to reduce this requirement
using Disk Data tables -- see *Note mysql-cluster-disk-data::, for more
information about these.) Naturally, multiple and faster CPUs can
enhance performance. Memory requirements for other Cluster processes are
relatively small.

The software requirements for Cluster are also modest. Host operating
systems do not require any unusual modules, services, applications, or
configuration to support MySQL Cluster. For supported operating
systems, a standard installation should be sufficient. The MySQL
software requirements are simple: all that is needed is a production
release of MySQL 5.1.24-ndb-6.2.16 or 5.1.24-ndb-6.3.17 to have Cluster
support. It is not necessary to compile MySQL yourself merely to be
able to use Cluster. In this `How-To', we assume that you are using the
server binary appropriate to your platform, available via the MySQL
Cluster software downloads page at
`http://dev.mysql.com/downloads/cluster'.

For communication between nodes, Cluster supports TCP/IP networking in
any standard topology, and the minimum expected for each host is a
standard 100 Mbps Ethernet card, plus a switch, hub, or router to
provide network connectivity for the cluster as a whole. We strongly
recommend that a MySQL Cluster be run on its own subnet which is not
shared with non-Cluster machines for the following reasons:

   * Security

     Communications between Cluster nodes are not encrypted or shielded
     in any way. The only means of protecting transmissions within a
     MySQL Cluster is to run your Cluster on a protected network. If
     you intend to use MySQL Cluster for Web applications, the cluster
     should definitely reside behind your firewall and not in your
     network's De-Militarized Zone (DMZ
     (http://compnetworking.about.com/cs/networksecurity/g/bldef_dmz.htm))
     or elsewhere.

     See *Note mysql-cluster-security-networking-issues::, for more
     information.

   * Efficiency

     Setting up a MySQL Cluster on a private or protected network
     allows the cluster to make exclusive use of bandwidth between
     cluster hosts. Using a separate switch for your MySQL Cluster not
     only helps protect against unauthorized access to Cluster data, it
     also ensures that Cluster nodes are shielded from interference
     caused by transmissions between other computers on the network.
     For enhanced reliability, you can use dual switches and dual cards
     to remove the network as a single point of failure; many device
     drivers support failover for such communication links.

It is also possible to use the high-speed Scalable Coherent Interface
(SCI) with MySQL Cluster, but this is not a requirement.  See *Note
mysql-cluster-interconnects::, for more about this protocol and its use
with MySQL Cluster.


File: manual.info,  Node: mysql-cluster-multi-install,  Next: mysql-cluster-multi-config,  Prev: mysql-cluster-multi-hardware-software-network,  Up: mysql-cluster-multi-computer

20.2.2 Multi-Computer Installation
----------------------------------

Each MySQL Cluster host computer running an SQL node must have
installed on it a MySQL binary. For management nodes and data nodes, it
is not necessary to install the MySQL server binary, but management
nodes require the management server daemon (`ndb_mgmd') and data nodes
require the data node daemon (`ndbd'). It is also a good idea to
install the management client (`ndb_mgm') on the management server
host. This section covers the steps necessary to install the correct
binaries for each type of Cluster node.

MySQL AB provides precompiled binaries that support Cluster, and there
is generally no need to compile these yourself. However, we also
include information relating to installing a MySQL Cluster after
building MySQL from source. For setting up a cluster using MySQL's
binaries, the first step in the installation process for each cluster
host is to download the file
`mysql-5.1.24-ndb-6.2.16-linux-i686-glibc23.tar.gz' from the MySQL
downloads area (http://dev.mysql.com/downloads/cluster). We assume that
you have placed it in each machine's `/var/tmp' directory. (If you do
require a custom binary, see *Note installing-source-tree::.)

*Note*:

After completing the installation, do not yet start any of the
binaries. We show you how to do so following the configuration of all
nodes.

Data and SQL Node Installation -- `.tar.gz' Binary

On each of the machines designated to host data or SQL nodes, perform
the following steps as the system `root' user:

  1. Check your `/etc/passwd' and `/etc/group' files (or use whatever
     tools are provided by your operating system for managing users and
     groups) to see whether there is already a `mysql' group and
     `mysql' user on the system. Some OS distributions create these as
     part of the operating system installation process. If they are not
     already present, create a new `mysql' user group, and then add a
     `mysql' user to this group:

          shell> groupadd mysql
          shell> useradd -g mysql mysql

     The syntax for `useradd' and `groupadd' may differ slightly on
     different versions of Unix, or they may have different names such
     as `adduser' and `addgroup'.

  2. Change location to the directory containing the downloaded file,
     unpack the archive, and create a symlink to the `mysql' directory
     named `mysql'. Note that the actual file and directory names will
     vary according to the MySQL version number.

          shell> cd /var/tmp
          shell> tar -C /usr/local -xzvf mysql-5.1.24-ndb-6.2.16-linux-i686-glibc23.tar.gz
          shell> ln -s /usr/local/mysql-5.1.24-ndb-6.2.16-linux-i686-glibc23.tar.gz /usr/local/mysql

  3. Change location to the `mysql' directory and run the supplied
     script for creating the system databases:

          shell> cd mysql
          shell> scripts/mysql_install_db --user=mysql

  4. Set the necessary permissions for the MySQL server and data
     directories:

          shell> chown -R root .
          shell> chown -R mysql data
          shell> chgrp -R mysql .

     Note that the data directory on each machine hosting a data node
     is `/usr/local/mysql/data'.  This piece of information is
     essential when configuring the management node. (See *Note
     mysql-cluster-multi-config::.)

  5. Copy the MySQL startup script to the appropriate directory, make
     it executable, and set it to start when the operating system is
     booted up:

          shell> cp support-files/mysql.server /etc/rc.d/init.d/
          shell> chmod +x /etc/rc.d/init.d/mysql.server
          shell> chkconfig --add mysql.server

     (The startup scripts directory may vary depending on your
     operating system and version -- for example, in some Linux
     distributions, it is `/etc/init.d'.)

     Here we use Red Hat's `chkconfig' for creating links to the
     startup scripts; use whatever means is appropriate for this
     purpose on your operating system and distribution, such as
     `update-rc.d' on Debian.

Remember that the preceding steps must be performed separately on each
machine where an SQL node is to reside.

SQL node installation -- building from source

If you compile MySQL with clustering support (for example, by using the
`BUILD/compile-PLATFORM_NAME-max' script appropriate to your platform),
and perform the default installation (using `make install' as the root
user), `mysqld' is placed in `/usr/local/mysql/bin'. Follow the steps
given in *Note installing-source:: to make `mysqld' ready for use. If
you want to run multiple SQL nodes, you can use a copy of the same
`mysqld' executable and its associated support files on several
machines. The easiest way to do this is to copy the entire
`/usr/local/mysql' directory and all directories and files contained
within it to the other SQL node host or hosts, then repeat the steps
from *Note installing-source:: on each machine. If you configure the
build with a non-default `--prefix', you need to adjust the directory
accordingly.

Data node installation -- building from source

The only executable required on a data node host is `ndbd' (`mysqld',
for example, does not have to be present on the host machine). By
default when doing a source build, this file is placed in the directory
`/usr/local/mysql/libexec'. For installing on multiple data node hosts,
only `ndbd' need be copied to the other host machine or machines. (This
assumes that all data node hosts use the same architecture and operating
system; otherwise you may need to compile separately for each different
platform.) `ndbd' need not be in any particular location on the host's
filesystem, as long as the location is known.

Management node installation -- `.tar.gz' binary

Installation of the management node does not require the `mysqld'
binary. Only the binary for the management server is required, which
can be found in the downloaded archive. You most likely want to install
the management client as well; this can also be found in the `.tar.gz'
archive. Again, we assume that you have placed this archive in
`/var/tmp'.

As system `root' (that is, after using `sudo', `su root', or your
system's equivalent for temporarily assuming the system administrator
account's privileges), perform the following steps to install
`ndb_mgmd' and `ndb_mgm' on the Cluster management node host:

  1. Change location to the `/var/tmp' directory, and extract the
     `ndb_mgm' and `ndb_mgmd' from the archive into a suitable
     directory such as `/usr/local/bin':

          shell> cd /var/tmp
          shell> tar -zxvf mysql-5.1.24-ndb-6.2.16-linux-i686-glibc23.tar.gz
          shell> cd mysql-5.1.24-ndb-6.2.16-linux-i686-glibc23
          shell> cp /bin/ndb_mgm* /usr/local/bin

     (You can safely delete the directory created by unpacking the
     downloaded archive, and the files it contains, from `/var/tmp' once
     `ndb_mgm' and `ndb_mgmd' have been copied to the executables
     directory.)

  2. Change location to the directory into which you copied the files,
     and then make both of them executable:

          shell> cd /usr/local/bin
          shell> chmod +x ndb_mgm*

Management node installation -- building from source

When building from source and running the default `make install', the
management server binary (`ndb_mgmd') is placed in
`/usr/local/mysql/libexec', while the management client binary
(`ndb_mgm') can be found in `/usr/local/mysql/bin'. Only `ndb_mgmd' is
required to be present on a management node host; however, it is also a
good idea to have `ndb_mgm' present on the same host machine.  Neither
of these executables requires a specific location on the host machine's
filesystem.

In *Note mysql-cluster-multi-config::, we create configuration files
for all of the nodes in our example Cluster.


File: manual.info,  Node: mysql-cluster-multi-config,  Next: mysql-cluster-multi-initial,  Prev: mysql-cluster-multi-install,  Up: mysql-cluster-multi-computer

20.2.3 Multi-Computer Configuration
-----------------------------------

For our four-node, four-host MySQL Cluster, it is necessary to write
four configuration files, one per node host.

   * Each data node or SQL node requires a `my.cnf' file that provides
     two pieces of information: a _connectstring_ that tells the node
     where to find the MGM node, and a line telling the MySQL server on
     this host (the machine hosting the data node) to run in NDB mode.

     For more information on connectstrings, see *Note
     mysql-cluster-connectstring::.

   * The management node needs a `config.ini' file telling it how many
     replicas to maintain, how much memory to allocate for data and
     indexes on each data node, where to find the data nodes, where to
     save data to disk on each data node, and where to find any SQL
     nodes.

*Configuring the Storage and SQL Nodes*

The `my.cnf' file needed for the data nodes is fairly simple. The
configuration file should be located in the `/etc' directory and can be
edited using any text editor. (Create the file if it does not exist.)
For example:

     shell> vi /etc/my.cnf

We show `vi' being used here to create the file, but any text editor
should work just as well.

For each data node and SQL node in our example setup, `my.cnf' should
look like this:

     # Options for mysqld process:
     [mysqld]
     ndbcluster                      # run NDB storage engine
     ndb-connectstring=192.168.0.10  # location of management server

     # Options for ndbd process:
     [mysql_cluster]
     ndb-connectstring=192.168.0.10  # location of management server

After entering the preceding information, save this file and exit the
text editor. Do this for the machines hosting data node `A', data node
`B', and the SQL node.

*Important*:

Once you have started a `mysqld' process with the `ndbcluster' and
`ndb-connectstring' parameters in the `[mysqld]' in the `my.cnf' file
as shown previously, you cannot execute any `CREATE TABLE' or `ALTER
TABLE' statements without having actually started the cluster.
Otherwise, these statements will fail with an error. _This is by
design_.

Configuring the management node

The first step in configuring the MGM node is to create the directory
in which the configuration file can be found and then to create the
file itself. For example (running as `root'):

     shell> mkdir /var/lib/mysql-cluster
     shell> cd /var/lib/mysql-cluster
     shell> vi config.ini

For our representative setup, the `config.ini' file should read as
follows:

     # Options affecting ndbd processes on all data nodes:
     [ndbd default]
     NoOfReplicas=2    # Number of replicas
     DataMemory=80M    # How much memory to allocate for data storage
     IndexMemory=18M   # How much memory to allocate for index storage
                       # For DataMemory and IndexMemory, we have used the
                       # default values. Since the "world" database takes up
                       # only about 500KB, this should be more than enough for
                       # this example Cluster setup.

     # TCP/IP options:
     [tcp default]
     portnumber=2202   # This the default; however, you can use any port that is free
                       # for all the hosts in the cluster
                       # Note: It is recommended that you do not specify the port
                       # number at all and allow the default value to be used instead

     # Management process options:
     [ndb_mgmd]
     hostname=192.168.0.10           # Hostname or IP address of MGM node
     datadir=/var/lib/mysql-cluster  # Directory for MGM node log files

     # Options for data node "A":
     [ndbd]
                                     # (one [ndbd] section per data node)
     hostname=192.168.0.30           # Hostname or IP address
     datadir=/usr/local/mysql/data   # Directory for this data node's data files

     # Options for data node "B":
     [ndbd]
     hostname=192.168.0.40           # Hostname or IP address
     datadir=/usr/local/mysql/data   # Directory for this data node's data files

     # SQL node options:
     [mysqld]
     hostname=192.168.0.20           # Hostname or IP address
                                     # (additional mysqld connections can be
                                     # specified for this node for various
                                     # purposes such as running ndb_restore)

*Note*:

The `world' database can be downloaded from
`http://dev.mysql.com/doc/', where it can be found listed under
`Examples'.

After all the configuration files have been created and these minimal
options have been specified, you are ready to proceed with starting the
cluster and verifying that all processes are running.  We discuss how
this is done in *Note mysql-cluster-multi-initial::.

For more detailed information about the available MySQL Cluster
configuration parameters and their uses, see *Note
mysql-cluster-config-file::, and *Note mysql-cluster-configuration::.
For configuration of MySQL Cluster as relates to making backups, see
*Note mysql-cluster-backup-configuration::.

*Note*:

The default port for Cluster management nodes is 1186; the default port
for data nodes is 2202. However, the cluster can automatically allocate
ports for data nodes from those that are already free.


File: manual.info,  Node: mysql-cluster-multi-initial,  Next: mysql-cluster-multi-load-data-queries,  Prev: mysql-cluster-multi-config,  Up: mysql-cluster-multi-computer

20.2.4 Initial Startup
----------------------

Starting the cluster is not very difficult after it has been
configured. Each cluster node process must be started separately, and
on the host where it resides. The management node should be started
first, followed by the data nodes, and then finally by any SQL nodes:

  1. On the management host, issue the following command from the
     system shell to start the management node process:

          shell> ndb_mgmd -f /var/lib/mysql-cluster/config.ini

     *Note*:

     `ndb_mgmd' must be told where to find its configuration file,
     using the `-f' or `--config-file' option. (See *Note
     mysql-cluster-ndb-mgmd-process::, for details.)

     For additional options which can be used with `ndb_mgmd', see
     *Note mysql-cluster-command-options::.

  2. On each of the data node hosts, run this command to start the
     `ndbd' process:

          shell> ndbd

  3. If you used RPM files to install MySQL on the cluster host where
     the SQL node is to reside, you can (and should) use the supplied
     startup script to start the MySQL server process on the SQL node.

If all has gone well, and the cluster has been set up correctly, the
cluster should now be operational. You can test this by invoking the
`ndb_mgm' management node client.  The output should look like that
shown here, although you might see some slight differences in the
output depending upon the exact version of MySQL that you are using:

     shell> ndb_mgm
     -- NDB Cluster -- Management Client --
     ndb_mgm> SHOW
     Connected to Management Server at: localhost:1186
     Cluster Configuration
     ---------------------
     [ndbd(NDB)]     2 node(s)
     id=2    @192.168.0.30  (Version: 5.1.24-ndb-6.2.16, Nodegroup: 0, Master)
     id=3    @192.168.0.40  (Version: 5.1.24-ndb-6.2.16, Nodegroup: 0)

     [ndb_mgmd(MGM)] 1 node(s)
     id=1    @192.168.0.10  (Version: 5.1.24-ndb-6.2.16)

     [mysqld(SQL)]   1 node(s)
     id=4   (Version: 5.1.24-ndb-6.2.16)

*Note*:

The SQL node is referenced here as `[mysqld(API)]'. This is perfectly
normal, and reflects the fact that the `mysqld' process is acting as a
cluster API node.

You should now be ready to work with databases, tables, and data in
MySQL Cluster. See *Note mysql-cluster-multi-load-data-queries::, for a
brief discussion.


File: manual.info,  Node: mysql-cluster-multi-load-data-queries,  Next: mysql-cluster-multi-shutdown-restart,  Prev: mysql-cluster-multi-initial,  Up: mysql-cluster-multi-computer

20.2.5 Loading Sample Data and Performing Queries
-------------------------------------------------

Working with data in MySQL Cluster is not much different from doing so
in MySQL without Cluster. There are two points to keep in mind:

   * For a table to be replicated in the cluster, it must use the
     `NDBCLUSTER' storage engine. To specify this, use the `ENGINE=NDB'
     or `ENGINE=NDBCLUSTER' table option. You can add this option when
     creating the table:

          CREATE TABLE TBL_NAME (COL_NAME COLUMN_DEFINITIONS) ENGINE=NDBCLUSTER;

     Alternatively, for an existing table that uses a different storage
     engine, use `ALTER TABLE' to change the table to use `NDBCLUSTER':

          ALTER TABLE TBL_NAME ENGINE=NDBCLUSTER;

   * Each `NDB' table _must_ have a primary key. If no primary key is
     defined by the user when a table is created, the `NDBCLUSTER'
     storage engine automatically generates a hidden one.

     *Note*:

     This hidden key takes up space just as does any other table index.
     It is not uncommon to encounter problems due to insufficient
     memory for accommodating these automatically created indexes.)

If you are importing tables from an existing database using the output
of `mysqldump', you can open the SQL script in a text editor and add
the `ENGINE' option to any table creation statements, or replace any
existing `ENGINE' (or `TYPE') options.  Suppose that you have the
`world' sample database on another MySQL server that does not support
MySQL Cluster, and you want to export the `City' table:

     shell> mysqldump --add-drop-table world City > city_table.sql

The resulting `city_table.sql' file will contain this table creation
statement (and the `INSERT' statements necessary to import the table
data):

     DROP TABLE IF EXISTS `City`;
     CREATE TABLE `City` (
       `ID` int(11) NOT NULL auto_increment,
       `Name` char(35) NOT NULL default '',
       `CountryCode` char(3) NOT NULL default '',
       `District` char(20) NOT NULL default '',
       `Population` int(11) NOT NULL default '0',
       PRIMARY KEY  (`ID`)
     ) ENGINE=MyISAM DEFAULT CHARSET=latin1;

     INSERT INTO `City` VALUES (1,'Kabul','AFG','Kabol',1780000);
     INSERT INTO `City` VALUES (2,'Qandahar','AFG','Qandahar',237500);
     INSERT INTO `City` VALUES (3,'Herat','AFG','Herat',186800);
     (REMAINING INSERT STATEMENTS OMITTED)

You need to make sure that MySQL uses the `NDB' storage engine for this
table. There are two ways that this can be accomplished. One of these
is to modify the table definition _before_ importing it into the Cluster
database. Using the `City' table as an example, modify the `ENGINE'
option of the definition as follows:

     DROP TABLE IF EXISTS `City`;
     CREATE TABLE `City` (
       `ID` int(11) NOT NULL auto_increment,
       `Name` char(35) NOT NULL default '',
       `CountryCode` char(3) NOT NULL default '',
       `District` char(20) NOT NULL default '',
       `Population` int(11) NOT NULL default '0',
       PRIMARY KEY  (`ID`)
     ) *ENGINE=NDBCLUSTER* DEFAULT CHARSET=latin1;

     INSERT INTO `City` VALUES (1,'Kabul','AFG','Kabol',1780000);
     INSERT INTO `City` VALUES (2,'Qandahar','AFG','Qandahar',237500);
     INSERT INTO `City` VALUES (3,'Herat','AFG','Herat',186800);
     (REMAINING INSERT STATEMENTS OMITTED)

This must be done for the definition of each table that is to be part
of the clustered database. The easiest way to accomplish this is to do
a search-and-replace on the file that contains the definitions and
replace all instances of `TYPE=ENGINE_NAME' or `ENGINE=ENGINE_NAME'
with `ENGINE=NDBCLUSTER'. If you do not want to modify the file, you
can use the unmodified file to create the tables, and then use `ALTER
TABLE' to change their storage engine. The particulars are given later
in this section.

Assuming that you have already created a database named `world' on the
SQL node of the cluster, you can then use the `mysql' command-line
client to read `city_table.sql', and create and populate the
corresponding table in the usual manner:

     shell> mysql world < city_table.sql

It is very important to keep in mind that the preceding command must be
executed on the host where the SQL node is running (in this case, on
the machine with the IP address `192.168.0.20').

To create a copy of the entire `world' database on the SQL node, use
`mysqldump' on the non-cluster server to export the database to a file
named `world.sql'; for example, in the `/tmp' directory. Then modify
the table definitions as just described and import the file into the SQL
node of the cluster like this:

     shell> mysql world < /tmp/world.sql

If you save the file to a different location, adjust the preceding
instructions accordingly.

Running `SELECT' queries on the SQL node is no different from running
them on any other instance of a MySQL server. To run queries from the
command line, you first need to log in to the MySQL Monitor in the
usual way (specify the `root' password at the `Enter password:' prompt):

     shell> mysql -u root -p
     Enter password:
     Welcome to the MySQL monitor.  Commands end with ; or \g.
     Your MySQL connection id is 1 to server version: 5.1.24-ndb-6.2.16

     Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

     mysql>

We simply use the MySQL server's `root' account and assume that you
have followed the standard security precautions for installing a MySQL
server, including setting a strong `root' password. For more
information, see *Note default-privileges::.

It is worth taking into account that Cluster nodes do _not_ make use of
the MySQL privilege system when accessing one another. Setting or
changing MySQL user accounts (including the `root' account) effects
only applications that access the SQL node, not interaction between
nodes. See *Note mysql-cluster-security-mysql-privileges::, for more
information.

If you did not modify the `ENGINE' clauses in the table definitions
prior to importing the SQL script, you should run the following
statements at this point:

     mysql> USE world;
     mysql> ALTER TABLE City ENGINE=NDBCLUSTER;
     mysql> ALTER TABLE Country ENGINE=NDBCLUSTER;
     mysql> ALTER TABLE CountryLanguage ENGINE=NDBCLUSTER;

Selecting a database and running a `SELECT' query against a table in
that database is also accomplished in the usual manner, as is exiting
the MySQL Monitor:

     mysql> USE world;
     mysql> SELECT Name, Population FROM City ORDER BY Population DESC LIMIT 5;
     +-----------+------------+
     | Name      | Population |
     +-----------+------------+
     | Bombay    |   10500000 |
     | Seoul     |    9981619 |
     | Sa~o Paulo |    9968485 |
     | Shanghai  |    9696300 |
     | Jakarta   |    9604900 |
     +-----------+------------+
     5 rows in set (0.34 sec)

     mysql> \q
     Bye

     shell>

Applications that use MySQL can employ standard APIs to access `NDB'
tables. It is important to remember that your application must access
the SQL node, and not the management or data nodes. This brief example
shows how we might execute the `SELECT' statement just shown by using
the PHP 5.X `mysqli' extension running on a Web server elsewhere on the
network:

     <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
       "http://www.w3.org/TR/html4/loose.dtd">
     <html>
     <head>
       <meta http-equiv="Content-Type"
             content="text/html; charset=iso-8859-1">
       <title>SIMPLE mysqli SELECT</title>
     </head>
     <body>
     <?php
       # connect to SQL node:
       $link = new mysqli('192.168.0.20', 'root', 'ROOT_PASSWORD', 'world');
       # parameters for mysqli constructor are:
       #   host, user, password, database

       if( mysqli_connect_errno() )
         die("Connect failed: " . mysqli_connect_error());

       $query = "SELECT Name, Population
                 FROM City
                 ORDER BY Population DESC
                 LIMIT 5";

       # if no errors...
       if( $result = $link->query($query) )
       {
     ?>
     <table border="1" width="40%" cellpadding="4" cellspacing ="1">
       <tbody>
       <tr>
         <th width="10%">City</th>
         <th>Population</th>
       </tr>
     <?
         # then display the results...
         while($row = $result->fetch_object())
           printf(<tr>\n  <td align=\"center\">%s</td><td>%d</td>\n</tr>\n",
                   $row->Name, $row->Population);
     ?>
       </tbody
     </table>
     <?
       # ...and verify the number of rows that were retrieved
         printf("<p>Affected rows: %d</p>\n", $link->affected_rows);
       }
       else
         # otherwise, tell us what went wrong
         echo mysqli_error();

       # free the result set and the mysqli connection object
       $result->close();
       $link->close();
     ?>
     </body>
     </html>

We assume that the process running on the Web server can reach the IP
address of the SQL node.

In a similar fashion, you can use the MySQL C API, Perl-DBI,
Python-mysql, or MySQL AB's own Connectors to perform the tasks of data
definition and manipulation just as you would normally with MySQL.


File: manual.info,  Node: mysql-cluster-multi-shutdown-restart,  Prev: mysql-cluster-multi-load-data-queries,  Up: mysql-cluster-multi-computer

20.2.6 Safe Shutdown and Restart
--------------------------------

To shut down the cluster, enter the following command in a shell on the
machine hosting the management node:

     shell> ndb_mgm -e shutdown

The `-e' option here is used to pass a command to the `ndb_mgm' client
from the shell. (See *Note mysql-cluster-command-options::, for more
information about this option.) The command causes the `ndb_mgm',
`ndb_mgmd', and any `ndbd' processes to terminate gracefully. Any SQL
nodes can be terminated using `mysqladmin shutdown' and other means.

To restart the cluster, run these commands:

   * On the management host (`192.168.0.10' in our example setup):

          shell> ndb_mgmd -f /var/lib/mysql-cluster/config.ini

   * On each of the data node hosts (`192.168.0.30' and `192.168.0.40'):

          shell> ndbd

   * On the SQL host (`192.168.0.20'):

          shell> mysqld_safe &

In a production setting, it is usually not desirable to shut down the
cluster completely. In many cases, even when making configuration
changes, or performing upgrades to the cluster hardware or software (or
both), which require shutting down individual host machines, it is
possible to do so without shutting down the cluster as a whole by
performing a _rolling restart_ of the cluster. For more information
about doing this, see *Note mysql-cluster-rolling-restart::.


File: manual.info,  Node: mysql-cluster-configuration,  Next: mysql-cluster-options-variables,  Prev: mysql-cluster-multi-computer,  Up: mysql-cluster

20.3 MySQL Cluster Configuration
================================

* Menu:

* mysql-cluster-building::       Building MySQL Cluster from Source Code
* mysql-cluster-installing::     Installing the Cluster Software
* mysql-cluster-quick::          Quick Test Setup of MySQL Cluster
* mysql-cluster-config-file::    Configuration File
* mysql-cluster-config-params-overview::  Overview of Cluster Configuration Parameters
* mysql-cluster-config-lcp-params::  Configuring Parameters for Local Checkpoints

A MySQL server that is part of a MySQL Cluster differs in only one
respect from a normal (non-clustered) MySQL server, in that it employs
the `NDBCLUSTER' storage engine. This engine is also referred to simply
as `NDB', and the two forms of the name are synonymous.

To avoid unnecessary allocation of resources, the server is configured
by default with the `NDB' storage engine disabled. To enable `NDB', you
must modify the server's `my.cnf' configuration file, or start the
server with the `--ndbcluster' option.

For more information about `--ndbcluster' and other MySQL server
options specific to MySQL Cluster, see *Note
mysql-cluster-mysqld-command-options::.

The MySQL server is a part of the cluster, so it also must know how to
access an MGM node to obtain the cluster configuration data. The
default behavior is to look for the MGM node on `localhost'. However,
should you need to specify that its location is elsewhere, this can be
done in `my.cnf' or on the MySQL server command line.  Before the `NDB'
storage engine can be used, at least one MGM node must be operational,
as well as any desired data nodes.


File: manual.info,  Node: mysql-cluster-building,  Next: mysql-cluster-installing,  Prev: mysql-cluster-configuration,  Up: mysql-cluster-configuration

20.3.1 Building MySQL Cluster from Source Code
----------------------------------------------

`NDB', the Cluster storage engine, is available in binary distributions
for Linux, Mac OS X, and Solaris. We are working to make Cluster run on
all operating systems supported by MySQL, including Windows.

If you choose to build from a source tarball or one of the MySQL
Cluster public development trees, be sure to use the
`--with-ndbcluster' option when running `configure'. You can also use
the `BUILD/compile-pentium-max' build script. Note that this script
includes OpenSSL, so you must either have or obtain OpenSSL to build
successfully, or else modify `compile-pentium-max' to exclude this
requirement. Of course, you can also just follow the standard
instructions for compiling your own binaries, and then perform the
usual tests and installation procedure. See *Note
installing-source-tree::.

`BUILD/compile-pentium-max' also includes OpenSSL, so you must either
have or obtain OpenSSL to build successfully, or else modify
`compile-pentium-max' to exclude this requirement. Of course, you can
also just follow the standard instructions for compiling your own
binaries, and then perform the usual tests and installation procedure.
See *Note installing-source-tree::.

You should also note that `compile-pentium-max' installs MySQL to the
directory `/usr/local/mysql', placing all MySQL Cluster executables,
scripts, databases, and support files in subdirectories under this
directory. If this is not what you desire, be sure to modify the script
accordingly.


File: manual.info,  Node: mysql-cluster-installing,  Next: mysql-cluster-quick,  Prev: mysql-cluster-building,  Up: mysql-cluster-configuration

20.3.2 Installing the Cluster Software
--------------------------------------

In the next few sections, we assume that you are already familiar with
installing MySQL, and here we cover only the differences between
configuring MySQL Cluster and configuring MySQL without clustering.
(See *Note installing::, if you require more information about the
latter.)

You will find Cluster configuration easiest if you have already have
all management and data nodes running first; this is likely to be the
most time-consuming part of the configuration. Editing the `my.cnf'
file is fairly straightforward, and this section will cover only any
differences from configuring MySQL without clustering.


File: manual.info,  Node: mysql-cluster-quick,  Next: mysql-cluster-config-file,  Prev: mysql-cluster-installing,  Up: mysql-cluster-configuration

20.3.3 Quick Test Setup of MySQL Cluster
----------------------------------------

To familiarize you with the basics, we will describe the simplest
possible configuration for a functional MySQL Cluster. After this, you
should be able to design your desired setup from the information
provided in the other relevant sections of this chapter.

First, you need to create a configuration directory such as
`/var/lib/mysql-cluster', by executing the following command as the
system `root' user:

     shell> mkdir /var/lib/mysql-cluster

In this directory, create a file named `config.ini' that contains the
following information. Substitute appropriate values for `HostName' and
`DataDir' as necessary for your system.

     # file "config.ini" - showing minimal setup consisting of 1 data node,
     # 1 management server, and 3 MySQL servers.
     # The empty default sections are not required, and are shown only for
     # the sake of completeness.
     # Data nodes must provide a hostname but MySQL Servers are not required
     # to do so.
     # If you don't know the hostname for your machine, use localhost.
     # The DataDir parameter also has a default value, but it is recommended to
     # set it explicitly.
     # Note: [db], [api], and [mgm] are aliases for [ndbd], [mysqld], and [ndb_mgmd],
     # respectively. [db] is deprecated and should not be used in new installations.

     [ndbd default]
     NoOfReplicas= 1

     [mysqld  default]
     [ndb_mgmd default]
     [tcp default]

     [ndb_mgmd]
     HostName= myhost.example.com

     [ndbd]
     HostName= myhost.example.com
     DataDir= /var/lib/mysql-cluster

     [mysqld]
     [mysqld]
     [mysqld]

You can now start the `ndb_mgmd' management server. By default, it
attempts to read the `config.ini' file in its current working
directory, so change location into the directory where the file is
located and then invoke `ndb_mgmd':

     shell> cd /var/lib/mysql-cluster
     shell> ndb_mgmd

Then start a single data node by running `ndbd':

     shell> ndbd

For command-line options which can be used when starting `ndbd', see
*Note mysql-cluster-command-options::.

By default, `ndbd' looks for the management server at `localhost' on
port 1186.

*Note*:

If you have installed MySQL from a binary tarball, you will need to
specify the path of the `ndb_mgmd' and `ndbd' servers explicitly.
(Normally, these will be found in `/usr/local/mysql/bin'.)

Finally, change location to the MySQL data directory (usually
`/var/lib/mysql' or `/usr/local/mysql/data'), and make sure that the
`my.cnf' file contains the option necessary to enable the NDB storage
engine:

     [mysqld]
     ndbcluster

You can now start the MySQL server as usual:

     shell> mysqld_safe --user=mysql &

Wait a moment to make sure the MySQL server is running properly.  If
you see the notice `mysql ended', check the server's `.err' file to
find out what went wrong.

If all has gone well so far, you now can start using the cluster.
Connect to the server and verify that the `NDBCLUSTER' storage engine
is enabled:

     shell> mysql
     Welcome to the MySQL monitor.  Commands end with ; or \g.
     Your MySQL connection id is 1 to server version: 5.1.28

     Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

     mysql> SHOW ENGINES\G
     ...
     *************************** 12. row ***************************
     Engine: NDBCLUSTER
     Support: YES
     Comment: Clustered, fault-tolerant, memory-based tables
     *************************** 13. row ***************************
     Engine: NDB
     Support: YES
     Comment: Alias for NDBCLUSTER
     ...

The row numbers shown in the preceding example output may be different
from those shown on your system, depending upon how your server is
configured.

Try to create an `NDBCLUSTER' table:

     shell> mysql
     mysql> USE test;
     Database changed

     mysql> CREATE TABLE ctest (i INT) ENGINE=NDBCLUSTER;
     Query OK, 0 rows affected (0.09 sec)

     mysql> SHOW CREATE TABLE ctest \G
     *************************** 1. row ***************************
            Table: ctest
     Create Table: CREATE TABLE `ctest` (
       `i` int(11) default NULL
     ) ENGINE=ndbcluster DEFAULT CHARSET=latin1
     1 row in set (0.00 sec)

To check that your nodes were set up properly, start the management
client:

     shell> ndb_mgm

Use the `SHOW' command from within the management client to obtain a
report on the cluster's status:

     ndb_mgm> SHOW
     Cluster Configuration
     ---------------------
     [ndbd(NDB)]     1 node(s)
     id=2    @127.0.0.1  (Version: 3.5.3, Nodegroup: 0, Master)

     [ndb_mgmd(MGM)] 1 node(s)
     id=1    @127.0.0.1  (Version: 3.5.3)

     [mysqld(API)]   3 node(s)
     id=3    @127.0.0.1  (Version: 3.5.3)
     id=4 (not connected, accepting connect from any host)
     id=5 (not connected, accepting connect from any host)

At this point, you have successfully set up a working MySQL Cluster.
You can now store data in the cluster by using any table created with
`ENGINE=NDBCLUSTER' or its alias `ENGINE=NDB'.


File: manual.info,  Node: mysql-cluster-config-file,  Next: mysql-cluster-config-params-overview,  Prev: mysql-cluster-quick,  Up: mysql-cluster-configuration

20.3.4 Configuration File
-------------------------

* Menu:

* mysql-cluster-config-example::  Basic Example Configuration
* mysql-cluster-connectstring::  The Cluster Connectstring
* mysql-cluster-computer-definition::  Defining Cluster Computers
* mysql-cluster-mgm-definition::  Defining the Management Server
* mysql-cluster-ndbd-definition::  Defining Data Nodes
* mysql-cluster-api-definition::  Defining SQL and Other API Nodes
* mysql-cluster-tcp-definition::  Cluster TCP/IP Connections
* mysql-cluster-tcp-definition-direct::  TCP/IP Connections Using Direct Connections
* mysql-cluster-shm-definition::  Shared-Memory Connections
* mysql-cluster-sci-definition::  SCI Transport Connections

Configuring MySQL Cluster requires working with two files:

   * `my.cnf': Specifies options for all MySQL Cluster executables.
     This file, with which you should be familiar with from previous
     work with MySQL, must be accessible by each executable running in
     the cluster.

   * `config.ini': This file is read only by the MySQL Cluster
     management server, which then distributes the information
     contained therein to all processes participating in the cluster.
     `config.ini' contains a description of each node involved in the
     cluster. This includes configuration parameters for data nodes and
     configuration parameters for connections between all nodes in the
     cluster. For a quick reference to the sections that can appear in
     this file, and what sorts of configuration parameters may be
     placed in each section, see Sections of the `config.ini' File.

We are continuously making improvements in Cluster configuration and
attempting to simplify this process. Although we strive to maintain
backward compatibility, there may be times when introduce an
incompatible change. In such cases we will try to let Cluster users
know in advance if a change is not backward compatible. If you find
such a change and we have not documented it, please report it in the
MySQL bugs database using the instructions given in *Note bug-reports::.


File: manual.info,  Node: mysql-cluster-config-example,  Next: mysql-cluster-connectstring,  Prev: mysql-cluster-config-file,  Up: mysql-cluster-config-file

20.3.4.1 Basic Example Configuration
....................................

To support MySQL Cluster, you will need to update `my.cnf' as shown in
the following example.  Note that the options shown here should not be
confused with those that are used in `config.ini' files.  You may also
specify these parameters on the command line when invoking the
executables.

     # my.cnf
     # example additions to my.cnf for MySQL Cluster
     # (valid in MySQL 5.1)

     # enable ndbcluster storage engine, and provide connectstring for
     # management server host (default port is 1186)
     [mysqld]
     ndbcluster
     ndb-connectstring=ndb_mgmd.mysql.com

     # provide connectstring for management server host (default port: 1186)
     [ndbd]
     connect-string=ndb_mgmd.mysql.com

     # provide connectstring for management server host (default port: 1186)
     [ndb_mgm]
     connect-string=ndb_mgmd.mysql.com

     # provide location of cluster configuration file
     [ndb_mgmd]
     config-file=/etc/config.ini

(For more information on connectstrings, see *Note
mysql-cluster-connectstring::.)

     # my.cnf
     # example additions to my.cnf for MySQL Cluster
     # (will work on all versions)

     # enable ndbcluster storage engine, and provide connectstring for management
     # server host to the default port 1186
     [mysqld]
     ndbcluster
     ndb-connectstring=ndb_mgmd.mysql.com:1186

*Important*:

Once you have started a `mysqld' process with the `ndbcluster' and
`ndb-connectstring' parameters in the `[mysqld]' in the `my.cnf' file
as shown previously, you cannot execute any `CREATE TABLE' or `ALTER
TABLE' statements without having actually started the cluster.
Otherwise, these statements will fail with an error.  _This is by
design_.

You may also use a separate `[mysql_cluster]' section in the cluster
`my.cnf' file for settings to be read and used by all executables:

     # cluster-specific settings
     [mysql_cluster]
     ndb-connectstring=ndb_mgmd.mysql.com:1186

For additional `NDB' variables that can be set in the `my.cnf' file, see
*Note server-system-variables::.

The configuration file is named `config.ini' by default. It is read by
`ndb_mgmd' at startup and can be placed anywhere. Its location and name
are specified by using `--config-file=PATH_NAME' on the `ndb_mgmd'
command line. If the configuration file is not specified, `ndb_mgmd' by
default tries to read a file named `config.ini' located in the current
working directory.

Currently, the configuration file is in INI format, which consists of
sections preceded by section headings (surrounded by square brackets),
followed by the appropriate parameter names and values. One deviation
from the standard INI format is that the parameter name and value can
be separated by a colon (``:'') as well as the equals sign (``='');
however, the equals sign is preferred. Another deviation is that
sections are not uniquely identified by section name. Instead, unique
sections (such as two different nodes of the same type) are identified
by a unique ID specified as a parameter within the section.

Default values are defined for most parameters, and can also be
specified in `config.ini'. To create a default value section, simply
add the word `default' to the section name. For example, an `[ndbd]'
section contains parameters that apply to a particular data node,
whereas an `[ndbd default]' section contains parameters that apply to
all data nodes. Suppose that all data nodes should use the same data
memory size. To configure them all, create an `[ndbd default]' section
that contains a `DataMemory' line to specify the data memory size.

At a minimum, the configuration file must define the computers and
nodes involved in the cluster and on which computers these nodes are
located. An example of a simple configuration file for a cluster
consisting of one management server, two data nodes and two MySQL
servers is shown here:

     # file "config.ini" - 2 data nodes and 2 SQL nodes
     # This file is placed in the startup directory of ndb_mgmd (the
     # management server)
     # The first MySQL Server can be started from any host. The second
     # can be started only on the host mysqld_5.mysql.com

     [ndbd default]
     NoOfReplicas= 2
     DataDir= /var/lib/mysql-cluster

     [ndb_mgmd]
     Hostname= ndb_mgmd.mysql.com
     DataDir= /var/lib/mysql-cluster

     [ndbd]
     HostName= ndbd_2.mysql.com

     [ndbd]
     HostName= ndbd_3.mysql.com

     [mysqld]
     [mysqld]
     HostName= mysqld_5.mysql.com

Each node has its own section in the `config.ini' file. For example,
this cluster has two data nodes, so the preceding configuration file
contains two `[ndbd]' sections defining these nodes.

*Note*:

Do not place comments on the same line as a section heading in the
`config.ini' file; this causes the management server not to start
because it cannot parse the configuration file in such cases.

*Sections of the `config.ini' File*

There are six different sections that you can use in the `config.ini'
configuration file, as described in the following list:

   * `[computer]': Defines cluster hosts. This is not required to
     configure a viable MySQL Cluster, but be may used as a convenience
     when setting up a large cluster.  See *Note
     mysql-cluster-computer-definition::, for more information.

   * `[ndbd]': Defines a cluster data node (`ndbd' process). See *Note
     mysql-cluster-ndbd-definition::, for details.

   * `[mysqld]': Defines the cluster's MySQL server nodes (also called
     SQL or API nodes). For a discussion of SQL node configuration, see
     *Note mysql-cluster-api-definition::.

   * `[mgm]' or `[ndb_mgmd]': Defines a cluster management server (MGM)
     node. For information concerning the configuration of MGM nodes,
     see *Note mysql-cluster-mgm-definition::.

   * `[tcp]': Defines a TCP/IP connection between cluster nodes, with
     TCP/IP being the default connection protocol. Normally, `[tcp]' or
     `[tcp default]' sections are not required to set up a MySQL
     Cluster, as the cluster handles this automatically; however, it
     may be necessary in some situations to override the defaults
     provided by the cluster.  See *Note
     mysql-cluster-tcp-definition::, for information about available
     TCP/IP configuration parameters and how to use them. (You may also
     find *Note mysql-cluster-tcp-definition-direct:: to be of interest
     in some cases.)

   * `[shm]': Defines shared-memory connections between nodes. In MySQL
     5.1, it is enabled by default, but should still be considered
     experimental. For a discussion of SHM interconnects, see *Note
     mysql-cluster-shm-definition::.

   * `[sci]':Defines _Scalable Coherent Interface_ connections between
     cluster data nodes. Such connections require software which, while
     freely available, is not part of the MySQL Cluster distribution,
     as well as specialised hardware. See *Note
     mysql-cluster-sci-definition:: for detailed information about SCI
     interconnects.

You can define `default' values for each section. All Cluster parameter
names are case-insensitive, which differs from parameters specified in
`my.cnf' or `my.ini' files.


File: manual.info,  Node: mysql-cluster-connectstring,  Next: mysql-cluster-computer-definition,  Prev: mysql-cluster-config-example,  Up: mysql-cluster-config-file

20.3.4.2 The Cluster Connectstring
..................................

With the exception of the MySQL Cluster management server (`ndb_mgmd'),
each node that is part of a MySQL Cluster requires a _connectstring_
that points to the management server's location. This connectstring is
used in establishing a connection to the management server as well as
in performing other tasks depending on the node's role in the cluster.
The syntax for a connectstring is as follows:

     <connectstring> :=
         [<nodeid-specification>,]<host-specification>[,<host-specification>]

     <nodeid-specification> := NODE_ID

     <host-specification> := HOST_NAME[:PORT_NUM]

`node_id' is an integer larger than 1 which identifies a node in
`config.ini'.  HOST_NAME is a string representing a valid Internet host
name or IP address.  PORT_NUM is an integer referring to a TCP/IP port
number.

     example 1 (long):    "nodeid=2,myhost1:1100,myhost2:1100,192.168.0.3:1200"
     example 2 (short):   "myhost1"

All nodes will use `localhost:1186' as the default connectstring value
if none is provided. If PORT_NUM is omitted from the connectstring, the
default port is 1186. This port should always be available on the
network because it has been assigned by IANA for this purpose (see
`http://www.iana.org/assignments/port-numbers' for details).

By listing multiple `<host-specification>' values, it is possible to
designate several redundant management servers. A cluster node will
attempt to contact successive management servers on each host in the
order specified, until a successful connection has been established.

There are a number of different ways to specify the connectstring:

   * Each executable has its own command-line option which enables
     specifying the management server at startup. (See the
     documentation for the respective executable.)

   * It is also possible to set the connectstring for all nodes in the
     cluster at once by placing it in a `[mysql_cluster]' section in
     the management server's `my.cnf' file.

   * For backward compatibility, two other options are available, using
     the same syntax:

       1. Set the `NDB_CONNECTSTRING' environment variable to contain
          the connectstring.

       2. Write the connectstring for each executable into a text file
          named `Ndb.cfg' and place this file in the executable's
          startup directory.

     However, these are now deprecated and should not be used for new
     installations.

The recommended method for specifying the connectstring is to set it on
the command line or in the `my.cnf' file for each executable.

The maximum length of a connectstring is 1024 characters.


File: manual.info,  Node: mysql-cluster-computer-definition,  Next: mysql-cluster-mgm-definition,  Prev: mysql-cluster-connectstring,  Up: mysql-cluster-config-file

20.3.4.3 Defining Cluster Computers
...................................

The `[computer]' section has no real significance other than serving as
a way to avoid the need of defining host names for each node in the
system. All parameters mentioned here are required.

   *  `Id'

     This is an integer value, used to refer to the host computer
     elsewhere in the configuration file. This is not the same as the
     node ID.

   *  `HostName'

     This is the computer's hostname or IP address.


File: manual.info,  Node: mysql-cluster-mgm-definition,  Next: mysql-cluster-ndbd-definition,  Prev: mysql-cluster-computer-definition,  Up: mysql-cluster-config-file

20.3.4.4 Defining the Management Server
.......................................

The `[ndb_mgmd]' section is used to configure the behavior of the
management server. `[mgm]' can be used as an alias; the two section
names are equivalent.  All parameters in the following list are
optional and assume their default values if omitted.

*Note*:

If neither the `ExecuteOnComputer' nor the `HostName' parameter is
present, the default value `localhost' will be assumed for both.

   * `Id'

     Each node in the cluster has a unique identity, which is
     represented by an integer value in the range 1 to 63 inclusive.
     This ID is used by all internal cluster messages for addressing
     the node.

   * `ExecuteOnComputer'

     This refers to the `Id' set for one of the computers defined in a
     `[computer]' section of the `config.ini' file.

   * `PortNumber'

     This is the port number on which the management server listens for
     configuration requests and management commands.

   * `HostName'

     Specifying this parameter defines the hostname of the computer on
     which the management node is to reside. To specify a hostname
     other than `localhost', either this parameter or
     `ExecuteOnComputer' is required.

   * `LogDestination'

     This parameter specifies where to send cluster logging
     information. There are three options in this regard -- `CONSOLE',
     `SYSLOG', and `FILE' -- with `FILE' being the default:

        * `CONSOLE' outputs the log to `stdout':

               CONSOLE

        * `SYSLOG' sends the log to a `syslog' facility, possible values
          being one of `auth', `authpriv', `cron', `daemon', `ftp',
          `kern', `lpr', `mail', `news', `syslog', `user', `uucp',
          `local0', `local1', `local2', `local3', `local4', `local5',
          `local6', or `local7'.

          *Note*:

          Not every facility is necessarily supported by every
          operating system.

               SYSLOG:facility=syslog

        * `FILE' pipes the cluster log output to a regular file on the
          same machine. The following values can be specified:

             * `filename': The name of the log file.

             * `maxsize': The maximum size (in bytes) to which the file
               can grow before logging rolls over to a new file. When
               this occurs, the old log file is renamed by appending .N
               to the filename, where N is the next number not yet used
               with this name.

             * `maxfiles': The maximum number of log files.

               FILE:filename=cluster.log,maxsize=1000000,maxfiles=6

          The default value for the `FILE' parameter is
          `FILE:filename=ndb_NODE_ID_cluster.log,maxsize=1000000,maxfiles=6',
          where NODE_ID is the ID of the node.

     It is possible to specify multiple log destinations separated by
     semicolons as shown here:

          CONSOLE;SYSLOG:facility=local0;FILE:filename=/var/log/mgmd

   * `ArbitrationRank'

     This parameter is used to define which nodes can act as
     arbitrators. Only management nodes and SQL nodes can be
     arbitrators. `ArbitrationRank' can take one of the following
     values:

        * `0': The node will never be used as an arbitrator.

        * `1': The node has high priority; that is, it will be
          preferred as an arbitrator over low-priority nodes.

        * `2': Indicates a low-priority node which be used as an
          arbitrator only if a node with a higher priority is not
          available for that purpose.

     Normally, the management server should be configured as an
     arbitrator by setting its `ArbitrationRank' to 1 (the default
     value) and that of all SQL nodes to 0.

     Beginning with MySQL 5.1.16 and MySQL Cluster NDB 6.1.3, it is
     possible to disable arbitration completely by setting
     `ArbitrationRank' to 0 on all management and SQL nodes.

   * `ArbitrationDelay'

     An integer value which causes the management server's responses to
     arbitration requests to be delayed by that number of milliseconds.
     By default, this value is 0; it is normally not necessary to
     change it.

   * `DataDir'

     This specifies the directory where output files from the
     management server will be placed. These files include cluster log
     files, process output files, and the daemon's process ID (PID)
     file. (For log files, this location can be overridden by setting
     the `FILE' parameter for `LogDestination' as discussed previously
     in this section.)

     The default value for this parameter is the directory in which
     `ndb_mgmd' is located.


File: manual.info,  Node: mysql-cluster-ndbd-definition,  Next: mysql-cluster-api-definition,  Prev: mysql-cluster-mgm-definition,  Up: mysql-cluster-config-file

20.3.4.5 Defining Data Nodes
............................

The `[ndbd]' and`[ndbd default]'sections are used to configure the
behavior of the cluster's data nodes. There are many parameters which
control buffer sizes, pool sizes, timeouts, and so forth. The only
mandatory parameters are:

   * Either `ExecuteOnComputer' or `HostName', which must be defined in
     the local `[ndbd]' section.

   * The parameter `NoOfReplicas', which must be defined in the`[ndbd
     default]'section, as it is common to all Cluster data nodes.

Most data node parameters are set in the `[ndbd default]' section. Only
those parameters explicitly stated as being able to set local values
are allowed to be changed in the `[ndbd]' section. Where present,
`HostName', `Id' and `ExecuteOnComputer' _must_ be defined in the local
`[ndbd]' section, and not in any other section of `config.ini'. In
other words, settings for these parameters are specific to one data
node.

For those parameters affecting memory usage or buffer sizes, it is
possible to use `K', `M', or `G' as a suffix to indicate units of 1024,
1024x1024, or 1024x1024x1024. (For example, `100K' means 100 x 1024 =
102400.)  Parameter names and values are currently case-sensitive.

Identifying data nodes

The `Id' value (that is, the data node identifier) can be allocated on
the command line when the node is started or in the configuration file.

   * `Id'

     This is the node ID used as the address of the node for all
     cluster internal messages. For data nodes, this is an integer in
     the range 1 to 49 inclusive. Each node in the cluster must have a
     unique identity.

   * `ExecuteOnComputer'

     This refers to the `Id' set for one of the computers defined in a
     `[computer]' section.

   * `HostName'

     Specifying this parameter defines the hostname of the computer on
     which the data node is to reside. To specify a hostname other than
     `localhost', either this parameter or `ExecuteOnComputer' is
     required.

   * `ServerPort' (_OBSOLETE_)

     Each node in the cluster uses a port to connect to other nodes.
     This port is used also for non-TCP transporters in the connection
     setup phase. The default port is allocated dynamically in such a
     way as to ensure that no two nodes on the same computer receive
     the same port number, so it should not normally be necessary to
     specify a value for this parameter.

   *  `TcpBind_INADDR_ANY'

     Setting this parameter to `TRUE' or `1' binds `IP_ADDR_ANY' so
     that connections can be made from anywhere (for autogenerated
     connections). The default is `FALSE' (`0').

     This parameter was added in MySQL Cluster NDB 6.2.0.

   * `NoOfReplicas'

     This global parameter can be set only in the `[ndbd default]'
     section, and defines the number of replicas for each table stored
     in the cluster. This parameter also specifies the size of node
     groups. A node group is a set of nodes all storing the same
     information.

     Node groups are formed implicitly. The first node group is formed
     by the set of data nodes with the lowest node IDs, the next node
     group by the set of the next lowest node identities, and so on. By
     way of example, assume that we have 4 data nodes and that
     `NoOfReplicas' is set to 2. The four data nodes have node IDs 2,
     3, 4 and 5. Then the first node group is formed from nodes 2 and 3,
     and the second node group by nodes 4 and 5. It is important to
     configure the cluster in such a manner that nodes in the same node
     groups are not placed on the same computer because a single
     hardware failure would cause the entire cluster to fail.

     If no node IDs are provided, the order of the data nodes will be
     the determining factor for the node group. Whether or not explicit
     assignments are made, they can be viewed in the output of the
     management client's `SHOW' statement.

     There is no default value for `NoOfReplicas'; the maximum possible
     value is 4. Currently, only the values 1 and 2 are actually
     supported (see Bug#18621 (http://bugs.mysql.com/18621)).

     *Important*:

     Setting `NoOfReplicas' to 1 means that there is only a single copy
     of all Cluster data; in this case, the loss of a single data node
     causes the cluster to fail because there are no additional copies
     of the data stored by that node.

     The value for this parameter must divide evenly into the number of
     data nodes in the cluster. For example, if there are two data
     nodes, then `NoOfReplicas' must be equal to either 1 or 2, since
     2/3 and 2/4 both yield fractional values; if there are four data
     nodes, then `NoOfReplicas' must be equal to 1, 2, or 4.

   * `DataDir'

     This parameter specifies the directory where trace files, log
     files, pid files and error logs are placed.

   * `FileSystemPath'

     This parameter specifies the directory where all files created for
     metadata, REDO logs, UNDO logs (for Disk Data tables) and data
     files are placed. The default is the directory specified by
     `DataDir'.

     *Note*:

     This directory must exist before the `ndbd' process is initiated.

     The recommended directory hierarchy for MySQL Cluster includes
     `/var/lib/mysql-cluster', under which a directory for the node's
     filesystem is created. The name of this subdirectory contains the
     node ID. For example, if the node ID is 2, this subdirectory is
     named `ndb_2_fs'.

   * `BackupDataDir'

     This parameter specifies the directory in which backups are
     placed. If omitted, the default backup location is the directory
     named `BACKUP' under the location specified by the `FileSystemPath'
     parameter. (See above.)

*Data Memory, Index Memory, and String Memory*

`DataMemory' and `IndexMemory' are `[ndbd]' parameters specifying the
size of memory segments used to store the actual records and their
indexes. In setting values for these, it is important to understand how
`DataMemory' and `IndexMemory' are used, as they usually need to be
updated to reflect actual usage by the cluster:

   * `DataMemory'

     This parameter defines the amount of space (in bytes) available
     for storing database records. The entire amount specified by this
     value is allocated in memory, so it is extremely important that
     the machine has sufficient physical memory to accommodate it.

     The memory allocated by `DataMemory' is used to store both the
     actual records and indexes. There is a 16-byte overhead on each
     record; an additional amount for each record is incurred because
     it is stored in a 32KB page with 128 byte page overhead (see
     below). There is also a small amount wasted per page due to the
     fact that each record is stored in only one page.

     For variable-size table attributes in MySQL 5.1, the data is
     stored on separate datapages, allocated from `DataMemory'.
     Variable-length records use a fixed-size part with an extra
     overhead of 4 bytes to reference the variable-size part. The
     variable-size part has 2 bytes overhead plus 2 bytes per attribute.

     The maximum record size is currently 8052 bytes.

     The memory space defined by `DataMemory' is also used to store
     ordered indexes, which use about 10 bytes per record. Each table
     row is represented in the ordered index. A common error among
     users is to assume that all indexes are stored in the memory
     allocated by `IndexMemory', but this is not the case: Only primary
     key and unique hash indexes use this memory; ordered indexes use
     the memory allocated by `DataMemory'. However, creating a primary
     key or unique hash index also creates an ordered index on the same
     keys, unless you specify `USING HASH' in the index creation
     statement. This can be verified by running `ndb_desc -d DB_NAME
     TABLE_NAME' in the management client.

     The memory space allocated by `DataMemory' consists of 32KB pages,
     which are allocated to table fragments. Each table is normally
     partitioned into the same number of fragments as there are data
     nodes in the cluster.  Thus, for each node, there are the same
     number of fragments as are set in `NoOfReplicas'.

     In addition, due to the way in which new pages are allocated when
     the capacity of the current page is exhausted, there is an
     additional overhead of approximately 18.75%. When more
     `DataMemory' is required, more than one new page is allocated,
     according to the following formula:

          number of new pages = FLOOR(number of current pages x 0.1875) + 1

     For example, if 15 pages are currently allocated to a given table
     and an insert to this table requires additional storage space, the
     number of new pages allocated to the table is `FLOOR(15 x 0.1875)
     + 1 = FLOOR(2.8125) + 1 = 2 + 1 = 3'. Now 15 + 3 = 18 memory pages
     are allocated to the table. When the last of these 18 pages
     becomes full, `FLOOR(18 x 0.1875) + 1 = FLOOR(3.3750) + 1 = 3 + 1 =
     4' new pages are allocated, so the total number of pages allocated
     to the table is now 22.

     *Note*:

     The `18.75% + 1' overhead is no longer required beginning with
     MySQL Cluster NDB 6.2.3 and MySQL Cluster NDB 6.3.0.

     Once a page has been allocated, it is currently not possible to
     return it to the pool of free pages, except by deleting the table.
     (This also means that `DataMemory' pages, once allocated to a
     given table, cannot be used by other tables.) Performing a node
     recovery also compresses the partition because all records are
     inserted into empty partitions from other live nodes.

     The `DataMemory' memory space also contains UNDO information: For
     each update, a copy of the unaltered record is allocated in the
     `DataMemory'.  There is also a reference to each copy in the
     ordered table indexes. Unique hash indexes are updated only when
     the unique index columns are updated, in which case a new entry in
     the index table is inserted and the old entry is deleted upon
     commit. For this reason, it is also necessary to allocate enough
     memory to handle the largest transactions performed by
     applications using the cluster. In any case, performing a few
     large transactions holds no advantage over using many smaller
     ones, for the following reasons:

        * Large transactions are not any faster than smaller ones

        * Large transactions increase the number of operations that are
          lost and must be repeated in event of transaction failure

        * Large transactions use more memory

     The default value for `DataMemory' is 80MB; the minimum is 1MB.
     There is no maximum size, but in reality the maximum size has to
     be adapted so that the process does not start swapping when the
     limit is reached. This limit is determined by the amount of
     physical RAM available on the machine and by the amount of memory
     that the operating system may commit to any one process. 32-bit
     operating systems are generally limited to 2-4GB per process;
     64-bit operating systems can use more. For large databases, it may
     be preferable to use a 64-bit operating system for this reason.

   * `IndexMemory'

     This parameter controls the amount of storage used for hash
     indexes in MySQL Cluster. Hash indexes are always used for primary
     key indexes, unique indexes, and unique constraints.  Note that
     when defining a primary key and a unique index, two indexes will
     be created, one of which is a hash index used for all tuple
     accesses as well as lock handling. It is also used to enforce
     unique constraints.

     The size of the hash index is 25 bytes per record, plus the size
     of the primary key. For primary keys larger than 32 bytes another
     8 bytes is added.

     The default value for `IndexMemory' is 18MB. The minimum is 1MB.

   * `StringMemory'

     This parameter determines how much memory is allocated for strings
     such as table names, and is specified in an `[ndbd]' or `[ndbd
     default]' section of the `config.ini' file. A value between `0'
     and `100' inclusive is interpreted as a percent of the maximum
     default value, which is calculated based on a number of factors
     including the number of tables, maximum table name size, maximum
     size of `.FRM' files, `MaxNoOfTriggers', maximum column name size,
     and maximum default column value. In general it is safe to assume
     that the maximum default value is approximately 5 MB for a MySQL
     Cluster having 1000 tables.

     A value greater than `100' is interpreted as a number of bytes.

     The default value is `5' -- that is, 5 percent of the default
     maximum, or roughly 5 KB. (Note that this is a change from
     previous versions of MySQL Cluster.)

     Under most circumstances, the default value should be sufficient,
     but when you have a great many Cluster tables (1000 or more), it
     is possible to get Error 773 `Out of string memory, please modify
     StringMemory config parameter: Permanent error: Schema error', in
     which case you should increase this value.  `25' (25 percent) is
     not excessive, and should prevent this error from recurring in all
     but the most extreme conditions.

The following example illustrates how memory is used for a table.
Consider this table definition:

     CREATE TABLE example (
       a INT NOT NULL,
       b INT NOT NULL,
       c INT NOT NULL,
       PRIMARY KEY(a),
       UNIQUE(b)
     ) ENGINE=NDBCLUSTER;

For each record, there are 12 bytes of data plus 12 bytes overhead.
Having no nullable columns saves 4 bytes of overhead.  In addition, we
have two ordered indexes on columns `a' and `b' consuming roughly 10
bytes each per record. There is a primary key hash index on the base
table using roughly 29 bytes per record. The unique constraint is
implemented by a separate table with `b' as primary key and `a' as a
column. This other table consumes an additional 29 bytes of index
memory per record in the `example' table as well 8 bytes of record data
plus 12 bytes of overhead.

Thus, for one million records, we need 58MB for index memory to handle
the hash indexes for the primary key and the unique constraint. We also
need 64MB for the records of the base table and the unique index table,
plus the two ordered index tables.

You can see that hash indexes takes up a fair amount of memory space;
however, they provide very fast access to the data in return. They are
also used in MySQL Cluster to handle uniqueness constraints.

Currently, the only partitioning algorithm is hashing and ordered
indexes are local to each node. Thus, ordered indexes cannot be used to
handle uniqueness constraints in the general case.

An important point for both `IndexMemory' and `DataMemory' is that the
total database size is the sum of all data memory and all index memory
for each node group. Each node group is used to store replicated
information, so if there are four nodes with two replicas, there will
be two node groups. Thus, the total data memory available is 2 x
`DataMemory' for each data node.

It is highly recommended that `DataMemory' and `IndexMemory' be set to
the same values for all nodes. Data distribution is even over all nodes
in the cluster, so the maximum amount of space available for any node
can be no greater than that of the smallest node in the cluster.

`DataMemory' and `IndexMemory' can be changed, but decreasing either of
these can be risky; doing so can easily lead to a node or even an
entire MySQL Cluster that is unable to restart due to there being
insufficient memory space. Increasing these values should be
acceptable, but it is recommended that such upgrades are performed in
the same manner as a software upgrade, beginning with an update of the
configuration file, and then restarting the management server followed
by restarting each data node in turn.

Updates do not increase the amount of index memory used. Inserts take
effect immediately; however, rows are not actually deleted until the
transaction is committed.

Transaction parameters

The next three `[ndbd]' parameters that we discuss are important
because they affect the number of parallel transactions and the sizes
of transactions that can be handled by the system.
`MaxNoOfConcurrentTransactions' sets the number of parallel
transactions possible in a node.  `MaxNoOfConcurrentOperations' sets
the number of records that can be in update phase or locked
simultaneously.

Both of these parameters (especially `MaxNoOfConcurrentOperations') are
likely targets for users setting specific values and not using the
default value. The default value is set for systems using small
transactions, to ensure that these do not use excessive memory.

   * `MaxNoOfConcurrentTransactions'

     Each cluster data node requires a transaction record for each
     active transaction in the cluster. The task of coordinating
     transactions is distributed among all of the data nodes. The total
     number of transaction records in the cluster is the number of
     transactions in any given node times the number of nodes in the
     cluster.

     Transaction records are allocated to individual MySQL servers.
     Each connection to a MySQL server requires at least one
     transaction record, plus an additional transaction object per
     table accessed by that connection. This means that a reasonable
     minimum for this parameter is

          MaxNoOfConcurrentTransactions =
              (maximum number of tables accessed in any single transaction + 1)
              * number of cluster SQL nodes

     For example, suppose that there are 4 SQL nodes using the cluster.
     A single join involving 5 tables requires 6 transaction records;
     if there are 5 such joins in a transaction, then 5 * 6 = 30
     transaction records are required for this transaction, per MySQL
     server, or 30 * 4 = 120 transaction records total.

     This parameter must be set to the same value for all cluster data
     nodes. This is due to the fact that, when a data node fails, the
     oldest surviving node re-creates the transaction state of all
     transactions that were ongoing in the failed node.

     Changing the value of `MaxNoOfConcurrentTransactions' requires a
     complete shutdown and restart of the cluster.

     The default value is 4096.

   * `MaxNoOfConcurrentOperations'

     It is a good idea to adjust the value of this parameter according
     to the size and number of transactions. When performing
     transactions of only a few operations each and not involving a
     great many records, there is no need to set this parameter very
     high. When performing large transactions involving many records
     need to set this parameter higher.

     Records are kept for each transaction updating cluster data, both
     in the transaction coordinator and in the nodes where the actual
     updates are performed. These records contain state information
     needed to find UNDO records for rollback, lock queues, and other
     purposes.

     This parameter should be set to the number of records to be
     updated simultaneously in transactions, divided by the number of
     cluster data nodes. For example, in a cluster which has four data
     nodes and which is expected to handle 1,000,000 concurrent updates
     using transactions, you should set this value to 1000000 / 4 =
     250000.

     Read queries which set locks also cause operation records to be
     created. Some extra space is allocated within individual nodes to
     accommodate cases where the distribution is not perfect over the
     nodes.

     When queries make use of the unique hash index, there are actually
     two operation records used per record in the transaction. The
     first record represents the read in the index table and the second
     handles the operation on the base table.

     The default value is 32768.

     This parameter actually handles two values that can be configured
     separately. The first of these specifies how many operation
     records are to be placed with the transaction coordinator. The
     second part specifies how many operation records are to be local
     to the database.

     A very large transaction performed on an eight-node cluster
     requires as many operation records in the transaction coordinator
     as there are reads, updates, and deletes involved in the
     transaction. However, the operation records of the are spread over
     all eight nodes. Thus, if it is necessary to configure the system
     for one very large transaction, it is a good idea to configure the
     two parts separately. `MaxNoOfConcurrentOperations' will always be
     used to calculate the number of operation records in the
     transaction coordinator portion of the node.

     It is also important to have an idea of the memory requirements
     for operation records. These consume about 1KB per record.

   * `MaxNoOfLocalOperations'

     By default, this parameter is calculated as 1.1 x
     `MaxNoOfConcurrentOperations'. This fits systems with many
     simultaneous transactions, none of them being very large. If there
     is a need to handle one very large transaction at a time and there
     are many nodes, it is a good idea to override the default value by
     explicitly specifying this parameter.

Transaction temporary storage

The next set of `[ndbd]' parameters is used to determine temporary
storage when executing a statement that is part of a Cluster
transaction. All records are released when the statement is completed
and the cluster is waiting for the commit or rollback.

The default values for these parameters are adequate for most
situations. However, users with a need to support transactions
involving large numbers of rows or operations may need to increase
these values to enable better parallelism in the system, whereas users
whose applications require relatively small transactions can decrease
the values to save memory.

   * `MaxNoOfConcurrentIndexOperations'

     For queries using a unique hash index, another temporary set of
     operation records is used during a query's execution phase. This
     parameter sets the size of that pool of records.  Thus, this
     record is allocated only while executing a part of a query. As
     soon as this part has been executed, the record is released. The
     state needed to handle aborts and commits is handled by the normal
     operation records, where the pool size is set by the parameter
     `MaxNoOfConcurrentOperations'.

     The default value of this parameter is 8192. Only in rare cases of
     extremely high parallelism using unique hash indexes should it be
     necessary to increase this value. Using a smaller value is
     possible and can save memory if the DBA is certain that a high
     degree of parallelism is not required for the cluster.

   * `MaxNoOfFiredTriggers'

     The default value of `MaxNoOfFiredTriggers' is 4000, which is
     sufficient for most situations. In some cases it can even be
     decreased if the DBA feels certain the need for parallelism in the
     cluster is not high.

     A record is created when an operation is performed that affects a
     unique hash index. Inserting or deleting a record in a table with
     unique hash indexes or updating a column that is part of a unique
     hash index fires an insert or a delete in the index table. The
     resulting record is used to represent this index table operation
     while waiting for the original operation that fired it to
     complete. This operation is short-lived but can still require a
     large number of records in its pool for situations with many
     parallel write operations on a base table containing a set of
     unique hash indexes.

   * `TransactionBufferMemory'

     The memory affected by this parameter is used for tracking
     operations fired when updating index tables and reading unique
     indexes. This memory is used to store the key and column
     information for these operations. It is only very rarely that the
     value for this parameter needs to be altered from the default.

     The default value for `TransactionBufferMemory' is 1MB.

     Normal read and write operations use a similar buffer, whose usage
     is even more short-lived. The compile-time parameter
     `ZATTRBUF_FILESIZE' (found in
     `ndb/src/kernel/blocks/Dbtc/Dbtc.hpp') set to 4000 x 128 bytes
     (500KB). A similar buffer for key information, `ZDATABUF_FILESIZE'
     (also in `Dbtc.hpp') contains 4000 x 16 = 62.5KB of buffer space.
     `Dbtc' is the module that handles transaction coordination.

Scans and buffering

There are additional `[ndbd]' parameters in the `Dblqh' module (in
`ndb/src/kernel/blocks/Dblqh/Dblqh.hpp') that affect reads and updates.
These include `ZATTRINBUF_FILESIZE', set by default to 10000 x 128
bytes (1250KB) and `ZDATABUF_FILE_SIZE', set by default to 10000*16
bytes (roughly 156KB) of buffer space. To date, there have been neither
any reports from users nor any results from our own extensive tests
suggesting that either of these compile-time limits should be increased.

   * `MaxNoOfConcurrentScans'

     This parameter is used to control the number of parallel scans
     that can be performed in the cluster. Each transaction coordinator
     can handle the number of parallel scans defined for this
     parameter. Each scan query is performed by scanning all partitions
     in parallel. Each partition scan uses a scan record in the node
     where the partition is located, the number of records being the
     value of this parameter times the number of nodes. The cluster
     should be able to sustain `MaxNoOfConcurrentScans' scans
     concurrently from all nodes in the cluster.

     Scans are actually performed in two cases. The first of these
     cases occurs when no hash or ordered indexes exists to handle the
     query, in which case the query is executed by performing a full
     table scan. The second case is encountered when there is no hash
     index to support the query but there is an ordered index. Using
     the ordered index means executing a parallel range scan. The order
     is kept on the local partitions only, so it is necessary to
     perform the index scan on all partitions.

     The default value of `MaxNoOfConcurrentScans' is 256. The maximum
     value is 500.

   * `MaxNoOfLocalScans'

     Specifies the number of local scan records if many scans are not
     fully parallelized. If the number of local scan records is not
     provided, it is calculated as the product of
     `MaxNoOfConcurrentScans' and the number of data nodes in the
     system. The minimum value is 32.

   * `BatchSizePerLocalScan'

     This parameter is used to calculate the number of lock records
     used to handle concurrent scan operations.

     The default value is 64; this value has a strong connection to the
     `ScanBatchSize' defined in the SQL nodes.

   * `LongMessageBuffer'

     This is an internal buffer used for passing messages within
     individual nodes and between nodes. Although it is highly unlikely
     that this would need to be changed, it is configurable. By
     default, it is set to 1MB.

*Memory Allocation*

`MaxAllocate'

This is the maximum size of the memory unit to use when allocating
memory for tables. In cases where `NDB' gives `Out of memory' errors,
but it is evident by examining the cluster logs or the output of `DUMP
1000' (see `DUMP 1000'
(http://dev.mysql.com/doc/ndbapi/en/ndb-internals-dump-command-1000.html))
that all available memory has not yet been used, you can increase the
value of this parameter (or `MaxNoOfTables', or both) in order to cause
`NDB' to make sufficient memory available.

This parameter was introduced in MySQL 5.1.20, MySQL Cluster NDB 6.1.12
and MySQL MySQL Cluster NDB 6.2.3.

Logging and checkpointing

These `[ndbd]' parameters control log and checkpoint behavior.

   * `NoOfFragmentLogFiles'

     This parameter sets the number of REDO log files for the node, and
     thus the amount of space allocated to REDO logging. Because the
     REDO log files are organized in a ring, it is extremely important
     that the first and last log files in the set (sometimes referred
     to as the `head' and `tail' log files, respectively) do not meet.
     When these approach one another too closely, the node begins
     aborting all transactions encompassing updates due to a lack of
     room for new log records.

     A `REDO' log record is not removed until three local checkpoints
     have been completed since that log record was inserted.
     Checkpointing frequency is determined by its own set of
     configuration parameters discussed elsewhere in this chapter.

     How these parameters interact and proposals for how to configure
     them are discussed in *Note mysql-cluster-config-lcp-params::.

     The default parameter value is 16, which by default means 16 sets
     of 4 16MB files for a total of 1024MB. Beginning with MySQL
     Cluster NDB 6.1.1, the size of the individual log files is
     configurable using the `FragmentLogFileSize' parameter; more
     information about this parameter can be found here.  In scenarios
     requiring a great many updates, the value for
     `NoOfFragmentLogFiles' may need to be set as high as 300 or even
     higher to provide sufficient space for REDO logs.

     If the checkpointing is slow and there are so many writes to the
     database that the log files are full and the log tail cannot be
     cut without jeopardizing recovery, all updating transactions are
     aborted with internal error code 410 (`Out of log file space
     temporarily'). This condition prevails until a checkpoint has
     completed and the log tail can be moved forward.

     *Important*:

     This parameter cannot be changed `on the fly'; you must restart
     the node using `--initial'. If you wish to change this value for
     all data nodes in a running cluster, you can do so via a rolling
     node restart (using `--initial' when starting each data node).

   * `FragmentLogFileSize'

     Setting this parameter allows you to control directly the size of
     redo log files. This can be useful in situations when MySQL
     Cluster is operating under a high load and it is unable to close
     fragment log files quickly enough before attemtping to open new
     ones (only 2 fragment log files can be open at one time);
     increasing the size of the fragment log files gives the cluster
     more time before having to open each new fragment log file. The
     default value for this parameter is 16M. `FragmentLogFileSize' was
     added in MySQL MySQL Cluster NDB 6.1.11.

     For more information about fragment log files, see the description
     of the NoOfFragmentLogFiles parameter.

   * `MaxNoOfOpenFiles'

     This parameter sets a ceiling on how many internal threads to
     allocate for open files. _Any situation requiring a change in this
     parameter should be reported as a bug_.

     The default value is 40.

   * `InitialNoOfOpenFiles'

     This parameter sets the initial number of internal threads to
     allocate for open files.

     The default value is 27.

   * `MaxNoOfSavedMessages'

     This parameter sets the maximum number of trace files that are
     kept before overwriting old ones. Trace files are generated when,
     for whatever reason, the node crashes.

     The default is 25 trace files.

Metadata objects

The next set of `[ndbd]' parameters defines pool sizes for metadata
objects, used to define the maximum number of attributes, tables,
indexes, and trigger objects used by indexes, events, and replication
between clusters.  Note that these act merely as `suggestions' to the
cluster, and any that are not specified revert to the default values
shown.

   * `MaxNoOfAttributes'

     Defines the number of attributes that can be defined in the
     cluster.

     The default value is 1000, with the minimum possible value being
     32. The maximum is 4294967039. Each attribute consumes around 200
     bytes of storage per node due to the fact that all metadata is
     fully replicated on the servers.

     When setting `MaxNoOfAttributes', it is important to prepare in
     advance for any `ALTER TABLE' statements that you might want to
     perform in the future. This is due to the fact, during the
     execution of `ALTER TABLE' on a Cluster table, 3 times the number
     of attributes as in the original table are used.  For example, if
     a table requires 100 attributes, and you want to be able to alter
     it later, you need to set the value of `MaxNoOfAttributes' to 300.
     Assuming that you can create all desired tables without any
     problems, a good rule of thumb is to add two times the number of
     attributes in the largest table to `MaxNoOfAttributes' to be sure.
     You should also verify that this number is sufficient by trying an
     actual `ALTER TABLE' after configuring the parameter. If this is
     not successful, increase `MaxNoOfAttributes' by another multiple of
     the original value and test it again.

   * `MaxNoOfTables'

     A table object is allocated for each table, unique hash index, and
     ordered index. This parameter sets the maximum number of table
     objects for the cluster as a whole.

     For each attribute that has a `BLOB' data type an extra table is
     used to store most of the `BLOB' data. These tables also must be
     taken into account when defining the total number of tables.

     The default value of this parameter is 128. The minimum is 8 and
     the maximum is 1600. Each table object consumes approximately 20KB
     per node.

   * `MaxNoOfOrderedIndexes'

     For each ordered index in the cluster, an object is allocated
     describing what is being indexed and its storage segments. By
     default, each index so defined also defines an ordered index. Each
     unique index and primary key has both an ordered index and a hash
     index.

     The default value of this parameter is 128. Each object consumes
     approximately 10KB of data per node.

   * `MaxNoOfUniqueHashIndexes'

     For each unique index that is not a primary key, a special table
     is allocated that maps the unique key to the primary key of the
     indexed table. By default, an ordered index is also defined for
     each unique index. To prevent this, you must specify the `USING
     HASH' option when defining the unique index.

     The default value is 64. Each index consumes approximately 15KB
     per node.

   * `MaxNoOfTriggers'

     Internal update, insert, and delete triggers are allocated for
     each unique hash index. (This means that three triggers are
     created for each unique hash index.) However, an _ordered_ index
     requires only a single trigger object. Backups also use three
     trigger objects for each normal table in the cluster.

     Replication between clusters also makes use of internal triggers.

     This parameter sets the maximum number of trigger objects in the
     cluster.

     The default value is 768.

   * `MaxNoOfIndexes'

     This parameter is deprecated in MySQL 5.1; you should use
     `MaxNoOfOrderedIndexes' and `MaxNoOfUniqueHashIndexes' instead.

     This parameter is used only by unique hash indexes. There needs to
     be one record in this pool for each unique hash index defined in
     the cluster.

     The default value of this parameter is 128.

Boolean parameters

The behavior of data nodes is also affected by a set of `[ndbd]'
parameters taking on boolean values.  These parameters can each be
specified as `TRUE' by setting them equal to `1' or `Y', and as `FALSE'
by setting them equal to `0' or `N'.

   * `LockPagesInMainMemory'

     For a number of operating systems, including Solaris and Linux, it
     is possible to lock a process into memory and so avoid any
     swapping to disk. This can be used to help guarantee the cluster's
     real-time characteristics.

     Beginning with MySQL 5.1.15 and MySQL Cluster NDB 6.1.1, this
     parameter takes one of the integer values `0', `1', or `2', which
     act as follows:

        * `0': Disables locking. This is the default value.

        * `1': Performs the lock after allocating memory for the
          process.

        * `2': Performs the lock before memory for the process is
          allocated.

     Previously, this parameter was a Boolean.  `0' or `false' was the
     default setting, and disabled locking. `1' or `true' enabled
     locking of the process after its memory was allocated.

     *Important*:

     Beginning with MySQL 5.1.15 and MySQL Cluster NDB 6.1.1, it is no
     longer possible to use `true' or `false' for the value of this
     parameter; when upgrading from a previous version, you must change
     the value to `0', `1', or `2'.

   * `StopOnError'

     This parameter specifies whether an `ndbd' process should exit or
     perform an automatic restart when an error condition is
     encountered.

     This feature is enabled by default.

   * `Diskless'

     It is possible to specify MySQL Cluster tables as _diskless_,
     meaning that tables are not checkpointed to disk and that no
     logging occurs. Such tables exist only in main memory. A
     consequence of using diskless tables is that neither the tables
     nor the records in those tables survive a crash. However, when
     operating in diskless mode, it is possible to run `ndbd' on a
     diskless computer.

     *Important*:

     This feature causes the _entire_ cluster to operate in diskless
     mode.

     When this feature is enabled, Cluster online backup is disabled.
     In addition, a partial start of the cluster is not possible.

     `Diskless' is disabled by default.

   * `ODirect'

     Enabling this parameter causes `NDB' to attempt using `O_DIRECT'
     writes for LCP, backups, and redo logs, often lowering `kswapd'
     and CPU usage.

     *Warning*:

     When using MySQL Cluster Linux, `ODirect' should be enabled for
     2.6 or newer kernels.

     This parameter was added in the following releases:

        * MySQL 5.1.20

        * MySQL Cluster NDB 6.1.11

        * MySQL Cluster NDB 6.2.3

        * MySQL Cluster NDB 6.3.0

     `ODirect' is disabled by default.

   * `RestartOnErrorInsert'

     This feature is accessible only when building the debug version
     where it is possible to insert errors in the execution of
     individual blocks of code as part of testing.

     This feature is disabled by default.

   * `CompressedBackup'

     Setting this parameter to `1' causes backup files to be
     compressed. The compression used is equivalent to `gzip --fast',
     and can save 50% or more of the space required on the data node to
     store uncompressed backup files. Compressed backups can be enabled
     for individual data nodes, or for all data nodes (by setting this
     parameter in the `[ndbd default]' section of the `config.ini'
     file).

     *Important*:

     You cannot restore a compressed backup to a cluster running a
     MySQL version that does not support this feature.

     The default value is `0' (disabled).

     This parameter was introduced in MySQL Cluster NDB 6.3.7.

   * `CompressedLCP'

     Setting this parameter to `1' causes local checkpoint files to be
     compressed. The compression used is equivalent to `gzip --fast',
     and can save 50% or more of the space required on the data node to
     store uncompressed checkpoint files. Compressed LCPs can be
     enabled for individual data nodes, or for all data nodes (by
     setting this parameter in the `[ndbd default]' section of the
     `config.ini' file).

     *Important*:

     You cannot restore a compressed local checkpoint to a cluster
     running a MySQL version that does not support this feature.

     The default value is `0' (disabled).

     This parameter was introduced in MySQL Cluster NDB 6.3.7.

*Controlling Timeouts, Intervals, and Disk Paging*

There are a number of `[ndbd]' parameters specifying timeouts and
intervals between various actions in Cluster data nodes. Most of the
timeout values are specified in milliseconds. Any exceptions to this
are mentioned where applicable.

   * `TimeBetweenWatchDogCheck'

     To prevent the main thread from getting stuck in an endless loop
     at some point, a `watchdog' thread checks the main thread. This
     parameter specifies the number of milliseconds between checks. If
     the process remains in the same state after three checks, the
     watchdog thread terminates it.

     This parameter can easily be changed for purposes of
     experimentation or to adapt to local conditions. It can be
     specified on a per-node basis although there seems to be little
     reason for doing so.

     The default timeout is 6000 milliseconds (6 seconds).

   * `TimeBetweenWatchDogCheckInitial'

     This is similar to the `TimeBetweenWatchDogCheck' parameter,
     except that `TimeBetweenWatchDogCheckInitial' controls the amount
     of time that passes between execution checks inside a database
     node in the early start phases during which memory is allocated.

     The default timeout is 6000 milliseconds (6 seconds).

     This parameter was added in MySQL 5.1.20.

   * `StartPartialTimeout'

     This parameter specifies how long the Cluster waits for all data
     nodes to come up before the cluster initialization routine is
     invoked. This timeout is used to avoid a partial Cluster startup
     whenever possible.

     The default value is 30000 milliseconds (30 seconds). 0 disables
     the timeout, in which case the cluster may start only if all nodes
     are available.

   * `StartPartitionedTimeout'

     If the cluster is ready to start after waiting for
     `StartPartialTimeout' milliseconds but is still possibly in a
     partitioned state, the cluster waits until this timeout has also
     passed.

     The default timeout is 60000 milliseconds (60 seconds).

   * `StartFailureTimeout'

     If a data node has not completed its startup sequence within the
     time specified by this parameter, the node startup fails. Setting
     this parameter to 0 (the default value) means that no data node
     timeout is applied.

     For nonzero values, this parameter is measured in milliseconds.
     For data nodes containing extremely large amounts of data, this
     parameter should be increased. For example, in the case of a data
     node containing several gigabytes of data, a period as long as
     10-15 minutes (that is, 600000 to 1000000 milliseconds) might be
     required to perform a node restart.

   * `HeartbeatIntervalDbDb'

     One of the primary methods of discovering failed nodes is by the
     use of heartbeats. This parameter states how often heartbeat
     signals are sent and how often to expect to receive them. After
     missing three heartbeat intervals in a row, the node is declared
     dead. Thus, the maximum time for discovering a failure through the
     heartbeat mechanism is four times the heartbeat interval.

     The default heartbeat interval is 1500 milliseconds (1.5 seconds).
     This parameter must not be changed drastically and should not vary
     widely between nodes. If one node uses 5000 milliseconds and the
     node watching it uses 1000 milliseconds, obviously the node will
     be declared dead very quickly. This parameter can be changed
     during an online software upgrade, but only in small increments.

   * `HeartbeatIntervalDbApi'

     Each data node sends heartbeat signals to each MySQL server (SQL
     node) to ensure that it remains in contact. If a MySQL server
     fails to send a heartbeat in time it is declared `dead,' in which
     case all ongoing transactions are completed and all resources
     released. The SQL node cannot reconnect until all activities
     initiated by the previous MySQL instance have been completed. The
     three-heartbeat criteria for this determination are the same as
     described for `HeartbeatIntervalDbDb'.

     The default interval is 1500 milliseconds (1.5 seconds).  This
     interval can vary between individual data nodes because each data
     node watches the MySQL servers connected to it, independently of
     all other data nodes.

   * `TimeBetweenLocalCheckpoints'

     This parameter is an exception in that it does not specify a time
     to wait before starting a new local checkpoint; rather, it is used
     to ensure that local checkpoints are not performed in a cluster
     where relatively few updates are taking place. In most clusters
     with high update rates, it is likely that a new local checkpoint
     is started immediately after the previous one has been completed.

     The size of all write operations executed since the start of the
     previous local checkpoints is added. This parameter is also
     exceptional in that it is specified as the base-2 logarithm of the
     number of 4-byte words, so that the default value 20 means 4MB (4 x
     2^20) of write operations, 21 would mean 8MB, and so on up to a
     maximum value of 31, which equates to 8GB of write operations.

     All the write operations in the cluster are added together.
     Setting `TimeBetweenLocalCheckpoints' to 6 or less means that
     local checkpoints will be executed continuously without pause,
     independent of the cluster's workload.

   * `TimeBetweenGlobalCheckpoints'

     When a transaction is committed, it is committed in main memory in
     all nodes on which the data is mirrored. However, transaction log
     records are not flushed to disk as part of the commit. The
     reasoning behind this behavior is that having the transaction
     safely committed on at least two autonomous host machines should
     meet reasonable standards for durability.

     It is also important to ensure that even the worst of cases -- a
     complete crash of the cluster -- is handled properly. To guarantee
     that this happens, all transactions taking place within a given
     interval are put into a global checkpoint, which can be thought of
     as a set of committed transactions that has been flushed to disk.
     In other words, as part of the commit process, a transaction is
     placed in a global checkpoint group. Later, this group's log
     records are flushed to disk, and then the entire group of
     transactions is safely committed to disk on all computers in the
     cluster.

     This parameter defines the interval between global checkpoints.
     The default is 2000 milliseconds.

   * `TimeBetweenEpochs'

     This parameter defines the interval between synchronisation epochs
     for MySQL Cluster Replication. The default value is 100
     milliseconds.

     `TimeBetweenEpochs' is part of the implementation of `micro-GCPs',
     which can be used to improve the performance of MySQL Cluster
     Replication. This parameter was introduced in MySQL Cluster NDB
     6.2.5 and MySQL Cluster NDB 6.3.2.

   * `TimeBetweenEpochsTimeout'

     This parameter defines a timeout for synchronisation epochs for
     MySQL Cluster Replication. If a node fails to participate in a
     global checkpoint within the time determined by this parameter,
     the node is shut down. The default value is 4000 milliseconds.

     `TimeBetweenEpochsTimeout' is part of the implementation of
     `micro-GCPs', which can be used to improve the performance of
     MySQL Cluster Replication. This parameter was introduced in
     MySQL-MySQL Cluster NDB 6.2.7 and MySQL Cluster NDB 6.3.4.

   * `MaxBufferedEpochs'

     The number of unprocessed epochs by which a subscribing node can
     lag behind. Exceeding this number causes a lagging subscriber to
     be disconnected.

     The default value of 100 is sufficient for most normal operations.
     If a subscribing node does lag enough to cause disconnections, it
     is usually due to network or scheduling issues with regard to
     processes or threads. (In rare circumstances, the problem may be
     due to a bug in the `NDB' client.) It may be desirable to set the
     value lower than the default when epochs are longer.

     Disconnection prevents client issues from affecting the data node
     service, running out of memory to buffer data, and eventually
     shutting down. Instead, only the client is affected as a result of
     the disconnect (by, for example gap events in the binlog), forcing
     the client to reconnect or restart the process.

   * `TimeBetweenInactiveTransactionAbortCheck'

     Timeout handling is performed by checking a timer on each
     transaction once for every interval specified by this parameter.
     Thus, if this parameter is set to 1000 milliseconds, every
     transaction will be checked for timing out once per second.

     The default value is 1000 milliseconds (1 second).

   * `TransactionInactiveTimeout'

     This parameter states the maximum time that is permitted to lapse
     between operations in the same transaction before the transaction
     is aborted.

     The default for this parameter is zero (no timeout). For a
     real-time database that needs to ensure that no transaction keeps
     locks for too long, this parameter should be set to a relatively
     small value. The unit is milliseconds.

   * `TransactionDeadlockDetectionTimeout'

     When a node executes a query involving a transaction, the node
     waits for the other nodes in the cluster to respond before
     continuing. A failure to respond can occur for any of the
     following reasons:

        * The node is `dead'

        * The operation has entered a lock queue

        * The node requested to perform the action could be heavily
          overloaded.

     This timeout parameter states how long the transaction coordinator
     waits for query execution by another node before aborting the
     transaction, and is important for both node failure handling and
     deadlock detection. In MySQL 5.1.10 and earlier versions, setting
     it too high could cause undesirable behavior in situations
     involving deadlocks and node failure. Beginning with MySQL 5.1.11,
     active transactions occurring during node failures are actively
     aborted by the Cluster Transaction Coordinator, and so high
     settings are no longer an issue with this parameter.

     The default timeout value is 1200 milliseconds (1.2 seconds).

   * `DiskSyncSize'

     This is the maximum number of bytes to store before flushing data
     to a local checkpoint file. This is done in order to prevent write
     buffering, which can impede performance significantly. This
     parameter is _not_ intended to take the place of
     `TimeBetweenLocalCheckpoints'.

     *Note*:

     When `ODirect' is enabled, it is not necessary to set
     `DiskSyncSize'; in fact, in such cases its value is simply ignored.

     The default value is 4M (4 megabytes).

     This parameter was added in MySQL 5.1.12.

   * `DiskCheckpointSpeed'

     The amount of data,in bytes per second, that is sent to disk
     during a local checkpoint.

     The default value is 10M (10 megabytes per second).

     This parameter was added in MySQL 5.1.12.

   * `DiskCheckpointSpeedInRestart'

     The amount of data,in bytes per second, that is sent to disk
     during a local checkpoint as part of a restart operation.

     The default value is 100M (100 megabytes per second).

     This parameter was added in MySQL 5.1.12.

   * `NoOfDiskPagesToDiskAfterRestartTUP'

     When executing a local checkpoint, the algorithm flushes all data
     pages to disk. Merely doing so as quickly as possible without any
     moderation is likely to impose excessive loads on processors,
     networks, and disks. To control the write speed, this parameter
     specifies how many pages per 100 milliseconds are to be written.
     In this context, a `page' is defined as 8KB. This parameter is
     specified in units of 80KB per second, so setting
     `NoOfDiskPagesToDiskAfterRestartTUP' to a value of `20' entails
     writing 1.6MB in data pages to disk each second during a local
     checkpoint. This value includes the writing of UNDO log records
     for data pages. That is, this parameter handles the limitation of
     writes from data memory. (See the entry for `IndexMemory' for
     information about index pages.)

     In short, this parameter specifies how quickly to execute local
     checkpoints. It operates in conjunction with
     `NoOfFragmentLogFiles', `DataMemory', and `IndexMemory'.

     For more information about the interaction between these
     parameters and possible strategies for choosing appropriate values
     for them, see *Note mysql-cluster-config-lcp-params::.

     The default value is 40 (3.2MB of data pages per second).

     *Note*:

     This parameter is deprecated as of MySQL 5.1.6. For MySQL 5.1.12
     and later versions, use DiskCheckpointSpeed and DiskSyncSize
     instead.

   * `NoOfDiskPagesToDiskAfterRestartACC'

     This parameter uses the same units as
     `NoOfDiskPagesToDiskAfterRestartTUP' and acts in a similar
     fashion, but limits the speed of writing index pages from index
     memory.

     The default value of this parameter is 20 (1.6MB of index memory
     pages per second).

     *Note*:

     This parameter is deprecated as of MySQL 5.1.6. For MySQL 5.1.12
     and later versions, use DiskCheckpointSpeed and DiskSyncSize.

   * `NoOfDiskPagesToDiskDuringRestartTUP'

     This parameter is used in a fashion similar to
     `NoOfDiskPagesToDiskAfterRestartTUP' and
     `NoOfDiskPagesToDiskAfterRestartACC', only it does so with regard
     to local checkpoints executed in the node when a node is
     restarting. A local checkpoint is always performed as part of all
     node restarts. During a node restart it is possible to write to
     disk at a higher speed than at other times, because fewer
     activities are being performed in the node.

     This parameter covers pages written from data memory.

     The default value is 40 (3.2MB per second).

     *Note*:

     This parameter is deprecated as of MySQL 5.1.6. For MySQL 5.1.12
     and later versions, use DiskCheckpointSpeedInRestart and
     DiskSyncSize.

   * `NoOfDiskPagesToDiskDuringRestartACC'

     Controls the number of index memory pages that can be written to
     disk during the local checkpoint phase of a node restart.

     As with `NoOfDiskPagesToDiskAfterRestartTUP' and
     `NoOfDiskPagesToDiskAfterRestartACC', values for this parameter
     are expressed in terms of 8KB pages written per 100 milliseconds
     (80KB/second).

     The default value is 20 (1.6MB per second).

     *Note*:

     This parameter is deprecated as of MySQL 5.1.6. For MySQL 5.1.12
     and later versions, use DiskCheckpointSpeedInRestart and
     DiskSyncSize.

   * `ArbitrationTimeout'

     This parameter specifies how long data nodes wait for a response
     from the arbitrator to an arbitration message. If this is
     exceeded, the network is assumed to have split.

     The default value is 1000 milliseconds (1 second).

Buffering and logging

Several `[ndbd]' configuration parameters enable the advanced user to
have more control over the resources used by node processes and to
adjust various buffer sizes at need.

These buffers are used as front ends to the file system when writing
log records to disk. If the node is running in diskless mode, these
parameters can be set to their minimum values without penalty due to
the fact that disk writes are `faked' by the `NDB' storage engine's
filesystem abstraction layer.

   * `UndoIndexBuffer'

     The UNDO index buffer, whose size is set by this parameter, is
     used during local checkpoints. The `NDB' storage engine uses a
     recovery scheme based on checkpoint consistency in conjunction
     with an operational REDO log. To produce a consistent checkpoint
     without blocking the entire system for writes, UNDO logging is
     done while performing the local checkpoint. UNDO logging is
     activated on a single table fragment at a time. This optimization
     is possible because tables are stored entirely in main memory.

     The UNDO index buffer is used for the updates on the primary key
     hash index. Inserts and deletes rearrange the hash index; the NDB
     storage engine writes UNDO log records that map all physical
     changes to an index page so that they can be undone at system
     restart. It also logs all active insert operations for each
     fragment at the start of a local checkpoint.

     Reads and updates set lock bits and update a header in the hash
     index entry. These changes are handled by the page-writing
     algorithm to ensure that these operations need no UNDO logging.

     This buffer is 2MB by default. The minimum value is 1MB, which is
     sufficient for most applications. For applications doing extremely
     large or numerous inserts and deletes together with large
     transactions and large primary keys, it may be necessary to
     increase the size of this buffer. If this buffer is too small, the
     NDB storage engine issues internal error code 677 (`Index UNDO
     buffers overloaded').

     *Important*:

     It is not safe to decrease the value of this parameter during a
     rolling restart.

   * `UndoDataBuffer'

     This parameter sets the size of the UNDO data buffer, which
     performs a function similar to that of the UNDO index buffer,
     except the UNDO data buffer is used with regard to data memory
     rather than index memory. This buffer is used during the local
     checkpoint phase of a fragment for inserts, deletes, and updates.

     Because UNDO log entries tend to grow larger as more operations
     are logged, this buffer is also larger than its index memory
     counterpart, with a default value of 16MB.

     This amount of memory may be unnecessarily large for some
     applications. In such cases, it is possible to decrease this size
     to a minimum of 1MB.

     It is rarely necessary to increase the size of this buffer.  If
     there is such a need, it is a good idea to check whether the disks
     can actually handle the load caused by database update activity. A
     lack of sufficient disk space cannot be overcome by increasing the
     size of this buffer.

     If this buffer is too small and gets congested, the NDB storage
     engine issues internal error code 891 (`Data UNDO buffers
     overloaded').

     *Important*:

     It is not safe to decrease the value of this parameter during a
     rolling restart.

   * `RedoBuffer'

     All update activities also need to be logged. The REDO log makes
     it possible to replay these updates whenever the system is
     restarted. The NDB recovery algorithm uses a `fuzzy' checkpoint of
     the data together with the UNDO log, and then applies the REDO log
     to play back all changes up to the restoration point.

     `RedoBuffer' sets the size of the buffer in which the REDO log is
     written, and is 8MB by default. The minimum value is 1MB.

     If this buffer is too small, the NDB storage engine issues error
     code 1221 (`REDO log buffers overloaded').

     *Important*:

     It is not safe to decrease the value of this parameter during a
     rolling restart.

Controlling log messages

In managing the cluster, it is very important to be able to control the
number of log messages sent for various event types to `stdout'. For
each event category, there are 16 possible event levels (numbered 0
through 15).  Setting event reporting for a given event category to
level 15 means all event reports in that category are sent to `stdout';
setting it to 0 means that there will be no event reports made in that
category.

By default, only the startup message is sent to `stdout', with the
remaining event reporting level defaults being set to 0. The reason for
this is that these messages are also sent to the management server's
cluster log.

An analogous set of levels can be set for the management client to
determine which event levels to record in the cluster log.

   * `LogLevelStartup'

     The reporting level for events generated during startup of the
     process.

     The default level is 1.

   * `LogLevelShutdown'

     The reporting level for events generated as part of graceful
     shutdown of a node.

     The default level is 0.

   * `LogLevelStatistic'

     The reporting level for statistical events such as number of
     primary key reads, number of updates, number of inserts,
     information relating to buffer usage, and so on.

     The default level is 0.

   * `LogLevelCheckpoint'

     The reporting level for events generated by local and global
     checkpoints.

     The default level is 0.

   * `LogLevelNodeRestart'

     The reporting level for events generated during node restart.

     The default level is 0.

   * `LogLevelConnection'

     The reporting level for events generated by connections between
     cluster nodes.

     The default level is 0.

   * `LogLevelError'

     The reporting level for events generated by errors and warnings by
     the cluster as a whole. These errors do not cause any node failure
     but are still considered worth reporting.

     The default level is 0.

   * `LogLevelCongestion'

     The reporting level for events generated by congestion.  These
     errors do not cause node failure but are still considered worth
     reporting.

     The default level is 0.

   * `LogLevelInfo'

     The reporting level for events generated for information about the
     general state of the cluster.

     The default level is 0.

   * `MemReportFrequency'

     This parameter controls how often data node memory usage reports
     are recorded in the cluster log; it is an integer value
     representing the number of seconds between reports.

     Each data node's data memory and index memory usage is logged as
     both a percentage and a number of 32 KB pages of the `DataMemory'
     and `IndexMemory', respectively, set in the `config.ini' file. For
     example, if `DataMemory' is equal to 100 MB, and a given data node
     is using 50 MB for data memory storage, the corresponding line in
     the cluster log might look like this:

          2006-12-24 01:18:16 [MgmSrvr] INFO -- Node 2: Data usage is 50%(1280 32K pages of total 2560)

     `MemReportFrequency' is not a required parameter. If used, it can
     be set for all cluster data nodes in the `[ndbd default]' section
     of `config.ini', and can also be set or overridden for individual
     data nodes in the corresponding `[ndbd]' sections of the
     configuration file. The minimum value -- which is also the default
     value -- is 0, in which case memory reports are logged only when
     memory usage reaches certain percentages (80%, 90%, and 100%), as
     mentioned in the discussion of statistics events in *Note
     mysql-cluster-log-events::.

     This parameter was added in MySQL Cluster 5.1.16 and MySQL Cluster
     NDB 6.1.0.

Backup parameters

The `[ndbd]' parameters discussed in this section define memory buffers
set aside for execution of online backups.

   * `BackupDataBufferSize'

     In creating a backup, there are two buffers used for sending data
     to the disk. The backup data buffer is used to fill in data
     recorded by scanning a node's tables. Once this buffer has been
     filled to the level specified as `BackupWriteSize' (see below),
     the pages are sent to disk. While flushing data to disk, the backup
     process can continue filling this buffer until it runs out of
     space. When this happens, the backup process pauses the scan and
     waits until some disk writes have completed freed up memory so
     that scanning may continue.

     The default value is 2MB.

   * `BackupLogBufferSize'

     The backup log buffer fulfills a role similar to that played by
     the backup data buffer, except that it is used for generating a
     log of all table writes made during execution of the backup. The
     same principles apply for writing these pages as with the backup
     data buffer, except that when there is no more space in the backup
     log buffer, the backup fails.  For that reason, the size of the
     backup log buffer must be large enough to handle the load caused
     by write activities while the backup is being made. See *Note
     mysql-cluster-backup-configuration::.

     The default value for this parameter should be sufficient for most
     applications. In fact, it is more likely for a backup failure to
     be caused by insufficient disk write speed than it is for the
     backup log buffer to become full. If the disk subsystem is not
     configured for the write load caused by applications, the cluster
     is unlikely to be able to perform the desired operations.

     It is preferable to configure cluster nodes in such a manner that
     the processor becomes the bottleneck rather than the disks or the
     network connections.

     The default value is 2MB.

   * `BackupMemory'

     This parameter is simply the sum of `BackupDataBufferSize' and
     `BackupLogBufferSize'.

     The default value is 2MB + 2MB = 4MB.

     *Important*:

     If `BackupDataBufferSize' and `BackupLogBufferSize' taken together
     exceed 4MB, then this parameter must be set explicitly in the
     `config.ini' file to their sum.

   * This parameter controls how often backup status reports are issued
     in the management client during a backup, as well as how often
     such reports are written to the cluster log (provided cluster
     event logging is configured to allow it -- see *Note
     mysql-cluster-logging-and-checkpointing::).
     `BackupReportFrequency' represents the time in seconds between
     backup status reports.

     The default value is 0.

     This parameter was added in MySQL Cluster NDB 6.2.3.

   * `BackupWriteSize'

     This parameter specifies the default size of messages written to
     disk by the backup log and backup data buffers.

     The default value is 32KB.

   * `BackupMaxWriteSize'

     This parameter specifies the maximum size of messages written to
     disk by the backup log and backup data buffers.

     The default value is 256KB.

*Important*:

When specifying these parameters, the following relationships must hold
true. Otherwise, the data node will be unable to start:

   * `BackupDataBufferSize >= BackupWriteSize + 188KB'

   * `BackupLogBufferSize >= BackupWriteSize + 16KB'

   * `BackupMaxWriteSize >= BackupWriteSize'

*Realtime Performance Parameters*

The `[ndbd]' parameters discussed in this section are used in
scheduling and locking of threads to specific CPUs on multiprocessor
data node hosts. They were introduced in MySQL Cluster NDB 6.3.4.

   * `LockExecuteThreadToCPU'

     This parameter specifies the ID of the CPU assigned to handle the
     `NDBCLUSTER' execution thread.

     The value of this parameter is an integer in the range 0 to 65535
     (inclusive). The default is 65535.

   * `LockMaintThreadsToCPU'

     This parameter specifies the ID of the CPU assigned to handle
     `NDBCLUSTER' maintenance threads.

     The value of this parameter is an integer in the range 0 to 65535
     (inclusive). The default is 65535.

   * `RealtimeScheduler'

     Setting this parameter to 1 enables real-time scheduling of
     `NDBCLUSTER' threads.

     The default is 0 (scheduling disabled).

   * `SchedulerExecutionTimer'

     This parameter specifies the time in microseconds for threads to
     be executed in the scheduler before being sent.

     The default is 50 μsec.

   * `SchedulerSpinTimer'

     This parameter specifies the time in microseconds for threads to
     be executed in the scheduler before sleeping.

     The default value is 0.


File: manual.info,  Node: mysql-cluster-api-definition,  Next: mysql-cluster-tcp-definition,  Prev: mysql-cluster-ndbd-definition,  Up: mysql-cluster-config-file

20.3.4.6 Defining SQL and Other API Nodes
.........................................

The `[mysqld]' and `[api]' sections in the `config.ini' file define the
behavior of the MySQL servers (SQL nodes) and other applications (API
nodes) used to access cluster data. None of the parameters shown is
required. If no computer or host name is provided, any host can use
this SQL or API node.

Generally speaking, a `[mysqld]' section is used to indicate a MySQL
server providing an SQL interface to the cluster, and an `[api]'
section is used for applications other than `mysqld' processes
accessing cluster data, but the two designations are actually
synonomous; you can, for instance, list parameters for a MySQL server
acting as an SQL node in an `[api]' section.

*Note*:

For a discussion of MySQL server options for MySQL Cluster, see *Note
mysql-cluster-mysqld-command-options::; for information about MySQL
server system variables relating to MySQL Cluster, see *Note
mysql-cluster-system-variables::.

   * `Id'

     The `Id' value is used to identify the node in all cluster
     internal messages. It must be an integer in the range 1 to 63
     inclusive, and must be unique among all node IDs within the
     cluster.

   * `ExecuteOnComputer'

     This refers to the `Id' set for one of the computers (hosts)
     defined in a `[computer]' section of the configuration file.

   * `HostName'

     Specifying this parameter defines the hostname of the computer on
     which the SQL node (API node) is to reside. To specify a hostname,
     either this parameter or `ExecuteOnComputer' is required.

     If no `HostName' or `ExecuteOnComputer' is specified in a given
     `[mysql]' or `[api]' section of the `config.ini' file, then an SQL
     or API node may connect using the corresponding `slot' from any
     host which can establish a network connection to the management
     server host machine.  _This differs from the default behavior for
     data nodes, where `localhost' is assumed for `HostName' unless
     otherwise specified_.

   * `ArbitrationRank'

     This parameter defines which nodes can act as arbitrators.  Both
     MGM nodes and SQL nodes can be arbitrators. A value of 0 means
     that the given node is never used as an arbitrator, a value of 1
     gives the node high priority as an arbitrator, and a value of 2
     gives it low priority. A normal configuration uses the management
     server as arbitrator, setting its `ArbitrationRank' to 1 (the
     default) and those for all SQL nodes to 0.

     Beginning with MySQL 5.1.16 and MySQL Cluster NDB 6.1.3, it is
     possible to disable arbitration completely by setting
     `ArbitrationRank' to 0 on all management and SQL nodes.

   * `ArbitrationDelay'

     Setting this parameter to any other value than 0 (the default)
     means that responses by the arbitrator to arbitration requests
     will be delayed by the stated number of milliseconds. It is
     usually not necessary to change this value.

   * `BatchByteSize'

     For queries that are translated into full table scans or range
     scans on indexes, it is important for best performance to fetch
     records in properly sized batches. It is possible to set the
     proper size both in terms of number of records (`BatchSize') and
     in terms of bytes (`BatchByteSize'). The actual batch size is
     limited by both parameters.

     The speed at which queries are performed can vary by more than 40%
     depending upon how this parameter is set. In future releases,
     MySQL Server will make educated guesses on how to set parameters
     relating to batch size, based on the query type.

     This parameter is measured in bytes and by default is equal to
     32KB.

   * `BatchSize'

     This parameter is measured in number of records and is by default
     set to 64. The maximum size is 992.

   * `MaxScanBatchSize'

     The batch size is the size of each batch sent from each data node.
     Most scans are performed in parallel to protect the MySQL Server
     from receiving too much data from many nodes in parallel; this
     parameter sets a limit to the total batch size over all nodes.

     The default value of this parameter is set to 256KB. Its maximum
     size is 16MB.

You can obtain some information from a MySQL server running as a
Cluster SQL node using `SHOW STATUS' in the `mysql' client, as shown
here:

     mysql> SHOW STATUS LIKE 'ndb%';
     +-----------------------------+---------------+
     | Variable_name               | Value         |
     +-----------------------------+---------------+
     | Ndb_cluster_node_id         | 5             |
     | Ndb_config_from_host        | 192.168.0.112 |
     | Ndb_config_from_port        | 1186          |
     | Ndb_number_of_storage_nodes | 4             |
     +-----------------------------+---------------+
     4 rows in set (0.02 sec)

For information about these Cluster system status variables, see *Note
server-status-variables::.


File: manual.info,  Node: mysql-cluster-tcp-definition,  Next: mysql-cluster-tcp-definition-direct,  Prev: mysql-cluster-api-definition,  Up: mysql-cluster-config-file

20.3.4.7 Cluster TCP/IP Connections
...................................

TCP/IP is the default transport mechanism for establishing connections
in MySQL Cluster. It is normally not necessary to define connections
because Cluster automatically set ups a connection between each of the
data nodes, between each data node and all MySQL server nodes, and
between each data node and the management server. (For one exception to
this rule, see *Note mysql-cluster-tcp-definition-direct::.)  `[tcp]'
sections in the `config.ini' file explicitly define TCP/IP connections
between nodes in the cluster.

It is necessary to define a connection only to override the default
connection parameters. In that case, it is necessary to define at least
`NodeId1', `NodeId2', and the parameters to change.

*Important*:

Any `[tcp]' sections in the `config.ini' file should be listed last,
following any other sections in the file. This is not required for a
`[tcp default]' section. This is a known issue with the way in which the
`config.ini' file is read by the cluster management server.

It is also possible to change the default values for these parameters
by setting them in the `[tcp default]' section.

   *  `NodeId1', `NodeId2'

     To identify a connection between two nodes it is necessary to
     provide their node IDs in the `[tcp]' section of the configuration
     file. These are the same unique `Id' values for each of these
     nodes as described in *Note mysql-cluster-api-definition::.

   * `SendBufferMemory'

     TCP transporters use a buffer to store all messages before
     performing the send call to the operating system. When this buffer
     reaches 64KB its contents are sent; these are also sent when a
     round of messages have been executed. To handle temporary overload
     situations it is also possible to define a bigger send buffer.

     The default size of the send buffer is 256 KB; 2MB is recommended
     in most situations in which it is necessary to set this parameter.
     The minimum size is 64 KB; the theoretical maximum is 4 GB.

   * `SendSignalId'

     To be able to retrace a distributed message datagram, it is
     necessary to identify each message. When this parameter is set to
     `Y', message IDs are transported over the network. This feature is
     disabled by default in production builds, and enabled in `-debug'
     builds.

   * `Checksum'

     This parameter is a boolean parameter (enabled by setting it to
     `Y' or `1', disabled by setting it to `N' or `0').  It is disabled
     by default. When it is enabled, checksums for all messages are
     calculated before they placed in the send buffer. This feature
     ensures that messages are not corrupted while waiting in the send
     buffer, or by the transport mechanism.

   * `PortNumber' (_OBSOLETE_)

     This formerly specified the port number to be used for listening
     for connections from other nodes. This parameter should no longer
     be used.

   * `ReceiveBufferMemory'

     Specifies the size of the buffer used when receiving data from the
     TCP/IP socket.

     The default value of this parameter from its of 64 KB; 1M is
     recommended in most situations where the size of the receive
     buffer needs to be set. The minimum possible value is 16K; the
     theoretical maximum is 4G.


File: manual.info,  Node: mysql-cluster-tcp-definition-direct,  Next: mysql-cluster-shm-definition,  Prev: mysql-cluster-tcp-definition,  Up: mysql-cluster-config-file

20.3.4.8 TCP/IP Connections Using Direct Connections
....................................................

Setting up a cluster using direct connections between data nodes
requires specifying explicitly the crossover IP addresses of the data
nodes so connected in the `[tcp]' section of the cluster `config.ini'
file.

In the following example, we envision a cluster with at least four
hosts, one each for a management server, an SQL node, and two data
nodes. The cluster as a whole resides on the `172.23.72.*' subnet of a
LAN. In addition to the usual network connections, the two data nodes
are connected directly using a standard crossover cable, and
communicate with one another directly using IP addresses in the
`1.1.0.*' address range as shown:

     # Management Server
     [ndb_mgmd]
     Id=1
     HostName=172.23.72.20

     # SQL Node
     [mysqld]
     Id=2
     HostName=172.23.72.21

     # Data Nodes
     [ndbd]
     Id=3
     HostName=172.23.72.22

     [ndbd]
     Id=4
     HostName=172.23.72.23

     # TCP/IP Connections
     [tcp]
     NodeId1=3
     NodeId2=4
     HostName1=1.1.0.1
     HostName2=1.1.0.2

The `HostNameN' parameter, where N is an integer, is used only when
specifying direct TCP/IP connections.

The use of direct connections between data nodes can improve the
cluster's overall efficiency by allowing the data nodes to bypass an
Ethernet device such as a switch, hub, or router, thus cutting down on
the cluster's latency. It is important to note that to take the best
advantage of direct connections in this fashion with more than two data
nodes, you must have a direct connection between each data node and
every other data node in the same node group.


File: manual.info,  Node: mysql-cluster-shm-definition,  Next: mysql-cluster-sci-definition,  Prev: mysql-cluster-tcp-definition-direct,  Up: mysql-cluster-config-file

20.3.4.9 Shared-Memory Connections
..................................

MySQL Cluster attempts to use the shared memory transporter and
configure it automatically where possible.  `[shm]' sections in the
`config.ini' file explicitly define shared-memory connections between
nodes in the cluster. When explicitly defining shared memory as the
connection method, it is necessary to define at least `NodeId1',
`NodeId2' and `ShmKey'. All other parameters have default values that
should work well in most cases.

*Important*:

_SHM functionality is considered experimental only_. It is not
officially supported in any MySQL release series up to and including
5.1. This means that you must determine for yourself or by using our
free resources (forums, mailing lists) whether it can be made to work
correctly in your specific case.

   * `NodeId1', `NodeId2'

     To identify a connection between two nodes it is necessary to
     provide node identifiers for each of them, as `NodeId1' and
     `NodeId2'.

   * `ShmKey'

     When setting up shared memory segments, a node ID, expressed as an
     integer, is used to identify uniquely the shared memory segment to
     use for the communication. There is no default value.

   * `ShmSize'

     Each SHM connection has a shared memory segment where messages
     between nodes are placed by the sender and read by the reader. The
     size of this segment is defined by `ShmSize'. The default value is
     1MB.

   * `SendSignalId'

     To retrace the path of a distributed message, it is necessary to
     provide each message with a unique identifier.  Setting this
     parameter to `Y' causes these message IDs to be transported over
     the network as well. This feature is disabled by default in
     production builds, and enabled in `-debug' builds.

   * `Checksum'

     This parameter is a boolean (`Y'/`N') parameter which is disabled
     by default. When it is enabled, checksums for all messages are
     calculated before being placed in the send buffer.

     This feature prevents messages from being corrupted while waiting
     in the send buffer. It also serves as a check against data being
     corrupted during transport.


File: manual.info,  Node: mysql-cluster-sci-definition,  Prev: mysql-cluster-shm-definition,  Up: mysql-cluster-config-file

20.3.4.10 SCI Transport Connections
...................................

`[sci]' sections in the `config.ini' file explicitly define SCI
(Scalable Coherent Interface) connections between cluster nodes.  Using
SCI transporters in MySQL Cluster is supported only when the MySQL
binaries are built using `--with-ndb-sci=/YOUR/PATH/TO/SCI'.  The PATH
should point to a directory that contains at a minimum `lib' and
`include' directories containing SISCI libraries and header files. (See
*Note mysql-cluster-interconnects:: for more information about SCI.)

In addition, SCI requires specialized hardware.

It is strongly recommended to use SCI Transporters only for
communication between `ndbd' processes. Note also that using SCI
Transporters means that the `ndbd' processes never sleep. For this
reason, SCI Transporters should be used only on machines having at least
two CPUs dedicated for use by `ndbd' processes.  There should be at
least one CPU per `ndbd' process, with at least one CPU left in reserve
to handle operating system activities.

   * `NodeId1', `NodeId2'

     To identify a connection between two nodes it is necessary to
     provide node identifiers for each of them, as `NodeId1' and
     `NodeId2'.

   * `Host1SciId0'

     This identifies the SCI node ID on the first Cluster node
     (identified by `NodeId1').

   *  `Host1SciId1'

     It is possible to set up SCI Transporters for failover between two
     SCI cards which then should use separate networks between the
     nodes. This identifies the node ID and the second SCI card to be
     used on the first node.

   *  `Host2SciId0'

     This identifies the SCI node ID on the second Cluster node
     (identified by `NodeId2').

   *  `Host2SciId1'

     When using two SCI cards to provide failover, this parameter
     identifies the second SCI card to be used on the second node.

   * `SharedBufferSize'

     Each SCI transporter has a shared memory segment used for
     communication between the two nodes. Setting the size of this
     segment to the default value of 1MB should be sufficient for most
     applications. Using a smaller value can lead to problems when
     performing many parallel inserts; if the shared buffer is too
     small, this can also result in a crash of the `ndbd' process.

   * `SendLimit'

     A small buffer in front of the SCI media stores messages before
     transmitting them over the SCI network. By default, this is set to
     8KB. Our benchmarks show that performance is best at 64KB but 16KB
     reaches within a few percent of this, and there was little if any
     advantage to increasing it beyond 8KB.

   * `SendSignalId'

     To trace a distributed message it is necessary to identify each
     message uniquely. When this parameter is set to `Y', message IDs
     are transported over the network. This feature is disabled by
     default in production builds, and enabled in `-debug' builds.

   * `Checksum'

     This parameter is a boolean value, and is disabled by default.
     When `Checksum' is enabled, checksums are calculated for all
     messages before they are placed in the send buffer. This feature
     prevents messages from being corrupted while waiting in the send
     buffer. It also serves as a check against data being corrupted
     during transport.


File: manual.info,  Node: mysql-cluster-config-params-overview,  Next: mysql-cluster-config-lcp-params,  Prev: mysql-cluster-config-file,  Up: mysql-cluster-configuration

20.3.5 Overview of Cluster Configuration Parameters
---------------------------------------------------

* Menu:

* mysql-cluster-config-params-ndbd::  Data Node Configuration Parameters
* mysql-cluster-config-params-mgm::  Management Node Configuration Parameters
* mysql-cluster-config-params-api::  SQL Node and API Node Configuration Parameters

The next three sections provide summary tables of MySQL Cluster
configuration parameters used in the `config.ini' file to govern the
cluster's functioning. Each table lists the parameters for one of the
Cluster node process types (`ndbd', `ndb_mgmd', and `mysqld'), and
includes the parameter's type as well as its default, minimum, and
maximum values as applicable.

It is also stated what type of restart is required (node restart or
system restart) -- and whether the restart must be done with
`--initial' -- to change the value of a given configuration parameter.
This information is provided in each table's *Restart Type* column,
which contains one of the values shown in this list:

   * `N': Node Restart

   * `IN': Initial Node Restart

   * `S': System Restart

   * `IS': Initial System Restart

When performing a node restart or an initial node restart, all of the
cluster's data nodes must be restarted in turn (also referred to as a
_rolling restart_). It is possible to update cluster configuration
parameters marked `N' or `IN' online -- that is, without shutting down
the cluster -- in this fashion. An initial node restart requires
restarting each `ndbd' process with the `--initial' option.

A system restart requires a complete shutdown and restart of the entire
cluster. An initial system restart requires taking a backup of the
cluster, wiping the cluster filesystem after shutdown, and then
restoring from the backup following the restart.

In any cluster restart, all of the cluster's management servers must be
restarted in order for them to read the updated configuration parameter
values.

*Important*:

Values for numeric cluster parameters can generally be increased
without any problems, although it is advisable to do so progressively,
making such adjustments in relatively small increments. However,
decreasing the values of such parameters -- particularly those relating
to memory usage and disk space -- is not to be undertaken lightly, and
it is recommended that you do so only following careful planning and
testing. In addition, it is the generally the case that parameters
relating to memory and disk usage which can be raised using a simple
node restart require an initial node restart to be lowered.

Because some of these parameters can be used for configuring more than
one type of cluster node, they may appear in more than one of the
tables.

(Note that `4294967039' -- which often appears as a maximum value in
these tables -- is equal to `2^32 - 2^8 - 1'.)


File: manual.info,  Node: mysql-cluster-config-params-ndbd,  Next: mysql-cluster-config-params-mgm,  Prev: mysql-cluster-config-params-overview,  Up: mysql-cluster-config-params-overview

20.3.5.1 Data Node Configuration Parameters
...........................................

The following table provides information about parameters used in the
`[ndbd]' or `[ndbd default]' sections of a `config.ini' file for
configuring MySQL Cluster data nodes. For detailed descriptions and
other additional information about each of these parameters, see *Note
mysql-cluster-ndbd-definition::.

_*Restart Type* Column Values_

   * `N': Node Restart

   * `IN': Initial Node Restart

   * `S': System Restart

   * `IS': Initial System Restart

See *Note mysql-cluster-config-params-overview::, for additional
explanations of these abbreviations.

*Parameter Name*       *Type/Units*                         *Default       *Minimum       *Maximum       *Restart Type*
                                                            Value*         Value*         Value*         
`ArbitrationTimeout'   milliseconds                         3000           10             4294967039     N
`BackupDataBufferSize' bytes                                2M             0              4294967039     N
`BackupDataDir'        string                               ``FileSystemPath'/BACKUP'N/A            N/A            IN
`BackupLogBufferSize'  bytes                                2M             0              4294967039     N
`BackupMemory'         bytes                                4M             0              4294967039     N
`BackupReportFrequency'seconds                              0              0              4294967039     N
(Added in MySQL                                                                                          
Cluster NDB 6.2.3)                                                                                       
`BackupWriteSize'      bytes                                32K            2K             4294967039     N
`BackupMaxWriteSize'   bytes                                256K           2K             4294967039     N
`BatchSizePerLocalScan'integer                              64             1              992            N
`CompressedBackup'     boolean                              0              0              1              N
(Added in MySQL                                                                                          
Cluster NDB 6.3.7)                                                                                       
`CompressedLCP'        boolean                              0              0              1              N
(Added in MySQL                                                                                          
Cluster NDB 6.3.7)                                                                                       
`DataDir'              string                               `/var/lib/mysql-cluster'N/A            N/A            IN
`DataMemory'           bytes                                80M            1M             1024G          N
                                                                                          (subject to    
                                                                                          available      
                                                                                          system RAM     
                                                                                          and size of    
                                                                                          `IndexMemory') 
`DiskCheckpointSpeed'  integer (number of bytes per second) 10M            1M             4294967039     N
(added in MySQL                                                                                          
5.1.12)                                                                                                  
`DiskCheckpointSpeedInRestart'integer (number of bytes per second) 100M           1M             4294967039     N
(added in MySQL                                                                                          
5.1.12)                                                                                                  
`Diskless'             true|false (`1'|`0')                 0              0              1              IS
`DiskPageBufferMemory' bytes                                64M            4M             1024G          N
(added in MySQL 5.1.6)                                                                                   
`DiskSyncSize' (added  integer (number of bytes)            4M             32K            4294967039     N
in MySQL 5.1.12)                                                                                         
`ExecuteOnComputer'    integer                                                                           
`FileSystemPath'       string                               value          N/A            N/A            IN
(Added in MySQL-MySQL                                       specified for                                
Cluster NDB 6.1.11)                                         `DataDir'                                    
`FragmentLogFileSize'  integer                              16M            4M             1G             IN
`HeartbeatIntervalDbApi'milliseconds                         1500           100            4294967039     N
`HeartbeatIntervalDbDb'milliseconds                         1500           10             4294967039     N
`HostName'             string                               `localhost'    N/A            N/A            S
`Id'                   integer                              _None_         1              49             N
`IndexMemory'          bytes                                18M            1M             1024G          N
                                                                                          (subject to    
                                                                                          available      
                                                                                          system RAM     
                                                                                          and size of    
                                                                                          `DataMemory')  
`InitialNoOfOpenFiles' integer                              27             20             4294967039     N
`LockExecuteThreadToCPU'integer                              65535          0              65535          N
(Added in MySQL-MySQL                                                                                    
Cluster NDB 6.3.4)                                                                                       
`LockMaintThreadsToCPU'integer                              65535          0              65535          N
(Added in MySQL-MySQL                                                                                    
Cluster NDB 6.3.4)                                                                                       
`LockPagesInMainMemory'_As of MySQL 5.1.15 and MySQL        0              0              1              N
                       Cluster NDB 6.1.1_: integer;                                                      
                       _previously_: true|false (`1'|`0')                                                
`LogLevelCheckpoint'   integer                              0              0              15             IN
`LogLevelCongestion'   integer                              0              0              15             N
`LogLevelConnection'   integer                              0              0              15             N
`LogLevelError'        integer                              0              0              15             N
`LogLevelInfo'         integer                              0              0              15             N
`LogLevelNodeRestart'  integer                              0              0              15             N
`LogLevelShutdown'     integer                              0              0              15             N
`LogLevelStartup'      integer                              1              0              15             N
`LogLevelStatistic'    integer                              0              0              15             N
`LongMessageBuffer'    bytes                                1M             512K           4294967039     N
`MaxAllocate' (Added   integer                              32M            1M             1G             N
in MySQL Cluster NDB                                                                                     
6.1.12 and MySQL MySQL                                                                                   
Cluster NDB 6.2.3)                                                                                       
`MaxBufferedEpochs'    integer                              100            0              100000         N
(Added in MySQL                                                                                          
Cluster NDB 6.2.14)                                                                                      
`MaxNoOfAttributes'    integer                              1000           32             4294967039     N
`MaxNoOfConcurrentIndexOperations'integer                              8K             0              4294967039     N
`MaxNoOfConcurrentOperations'integer                              32768          32             4294967039     N
`MaxNoOfConcurrentScans'integer                              256            2              500            N
`MaxNoOfConcurrentTransactions'integer                              4096           32             4294967039     N
`MaxNoOfFiredTriggers' integer                              4000           0              4294967039     N
`MaxNoOfIndexes'       integer                              128            0              4294967039     N
(_DEPRECATED_ -- use                                                                                     
`MaxNoOfOrderedIndexes'                                                                                  
or                                                                                                       
`MaxNoOfUniqueHashIndexes'                                                                                  
instead)                                                                                                 
`MaxNoOfLocalOperations'integer                              `UNDEFINED'    32             4294967039     N
`MaxNoOfLocalScans'    integer                              `UNDEFINED'    32             4294967039     N
                                                            (see                                         
                                                            description)                                 
`MaxNoOfOpenFiles'     integer                              40             20             4294967039     N
`MaxNoOfOrderedIndexes'integer                              128            0              4294967039     N
`MaxNoOfSavedMessages' integer                              25             0              4294967039     N
`MaxNoOfTables'        integer                              128            8              4294967039     N
`MaxNoOfTriggers'      integer                              768            0              4294967039     N
`MaxNoOfUniqueHashIndexes'integer                              64             0              4294967039     N
`MemReportFrequency'   integer (seconds)                    0              0              4294967039     N
(Added in MySQL                                                                                          
5.1.16 and MySQL                                                                                         
Cluster NDB 6.1.0)                                                                                       
`NoOfDiskPagesToDiskAfterRestartACC'integer (number of 8KB pages per     20 (= 20 *     1              4294967039     N
(_DEPRECATED_ as of    100 milliseconds)                    80KB =                                       
MySQL 5.1.6)                                                1.6MB/second)                                
`NoOfDiskPagesToDiskAfterRestartTUP'integer (number of 8KB pages per     40 (= 40 *     1              4294967039     N
(_DEPRECATED_ as of    100 milliseconds)                    80KB =                                       
MySQL 5.1.6)                                                3.2MB/second)                                
`NoOfDiskPagesToDiskDuringRestartACC'integer (number of 8KB pages per     20 (= 20 *     1              4294967039     N
(_DEPRECATED_ as of    100 milliseconds)                    80KB =                                       
MySQL 5.1.6)                                                1.6MB/second)                                
`NoOfDiskPagesToDiskDuringRestartTUP'integer (number of 8KB pages per     40 (= 40 *     1              4294967039     N
(_DEPRECATED_ as of    100 milliseconds)                    80KB =                                       
MySQL 5.1.6)                                                3.2MB/second)                                
`NoOfFragmentLogFiles' integer                              16             3              4294967039     IN
`NoOfReplicas'         integer                              _None_         1              4              IS
                                                                                          (theoretical); 
                                                                                          2 (supported)  
`ODirect'              boolean                              0              0              1              N
`RealTimeScheduler'    boolean                              0              0              1              N
(Added in MySQL                                                                                          
Cluster NDB 6.3.4)                                                                                       
`RedoBuffer'           bytes                                8M             1M             4294967039     N
`RestartOnErrorInsert' true|false (`1'|`0')                 0              0              1              N
(_DEBUG BUILDS ONLY_)                                                                                    
`SchedulerExecutionTimer'μseconds (integer)                  50             0              11000          N
(added in MySQL                                                                                          
Cluster NDB 6.3.4)                                                                                       
`SchedulerSpinTimer'   μseconds (integer)                  0              0              500            N
(added in MySQL                                                                                          
Cluster NDB 6.3.4)                                                                                       
`ServerPort'           integer                              1186           0              4294967039     N
(_OBSOLETE_)                                                                                             
`SharedGlobalmemory'   bytes                                20M            0              65536G         N
(added in MySQL 5.1.6)                                                                                   
`StartFailureTimeout'  milliseconds                         0              0              4294967039     N
`StartPartialTimeout'  milliseconds                         30000          0              4294967039     N
`StartPartitionedTimeout'milliseconds                         60000          0              4294967039     N
`StopOnError'          true|false (`1'|`0')                 1              0              1              N
`StringMemory'         integer or percentage (see           0              0              4294967039     S
                       description for details)                                                          
`TcpBind_INADDR_ANY'   true|false (`1'|`0')                 1              0              0              N
(Added in MySQL                                                                                          
Cluster NDB 6.2.0)                                                                                       
`TimeBetweenEpochs'    milliseconds                         100            0              32000          N
(Added in MySQL                                                                                          
Cluster NDB 6.2.5 and                                                                                    
MySQL Cluster NDB                                                                                        
6.3.2)                                                                                                   
`TimeBetweenEpochsTimeout'milliseconds                         4000           0              32000          N
(Added in MySQL                                                                                          
Cluster NDB 6.2.7 and                                                                                    
MySQL Cluster NDB                                                                                        
6.3.4)                                                                                                   
`TimeBetweenGlobalCheckpoints'milliseconds                         2000           10             32000          N
`TimeBetweenInactiveTransactionAbortCheck'milliseconds                         1000           1000           4294967039     N
`TimeBetweenLocalCheckpoints'integer (number of 4-byte words as   20 (= `4 *     0              31             N
                       a base-2 logarithm)                  2^20' = 4MB                                  
                                                            write                                        
                                                            operations)                                  
`TimeBetweenWatchDogCheck'milliseconds                         6000           70             4294967039     N
`TimeBetweenWatchDogCheckInitial'milliseconds                         6000           70             4294967039     N
(added in MySQL                                                                                          
5.1.20)                                                                                                  
`TransactionBufferMemory'bytes                                1M             1K             4294967039     N
`TransactionDeadlockDetectionTimeout'milliseconds                         1200           50             4294967039     N
`TransactionInactiveTimeout'milliseconds                         0              0              4294967039     N
`UndoDataBuffer'       bytes                                16M            1M             4294967039     N
(_OBSOLETE_)                                                                                             
`UndoIndexBuffer'      bytes                                2M             1M             4294967039     N
(_OBSOLETE_)                                                                                             


File: manual.info,  Node: mysql-cluster-config-params-mgm,  Next: mysql-cluster-config-params-api,  Prev: mysql-cluster-config-params-ndbd,  Up: mysql-cluster-config-params-overview

20.3.5.2 Management Node Configuration Parameters
.................................................

The following table provides information about parameters used in the
`[ndb_mgmd]' or `[mgm]' sections of a `config.ini' file for configuring
MySQL Cluster management nodes. For detailed descriptions and other
additional information about each of these parameters, see *Note
mysql-cluster-mgm-definition::.

_*Restart Type* Column Values_

   * `N': Node Restart

   * `IN': Initial Node Restart

   * `S': System Restart

   * `IS': Initial System Restart

See *Note mysql-cluster-config-params-overview::, for additional
explanations of these abbreviations.

*Parameter Name*       *Type/Units*                         *Default       *Minimum       *Maximum       *Restart Type*
                                                            Value*         Value*         Value*         
`ArbitrationDelay'     milliseconds                         0              0              4294967039     N
`ArbitrationRank'      integer                              1              0              2              N
`DataDir'              string                               `./'           N/A            N/A            IN
                                                            (`ndb_mgmd'                                  
                                                            directory)                                   
`ExecuteOnComputer'    integer                                                                           
`HostName'             string                               `localhost'    N/A            N/A            IN
`Id'                   integer                              _None_         1              63             IN
`LogDestination'       `CONSOLE', `SYSLOG', or `FILE'       `FILE' (see    N/A            N/A            N
                                                            *Note                                        
                                                            mysql-cluster-mgm-definition::)                              
`PortNumber'           integer                              1186           1              65535          S


File: manual.info,  Node: mysql-cluster-config-params-api,  Prev: mysql-cluster-config-params-mgm,  Up: mysql-cluster-config-params-overview

20.3.5.3 SQL Node and API Node Configuration Parameters
.......................................................

The following table provides information about parameters used in the
`[SQL]' and `[api]' sections of a `config.ini' file for configuring
MySQL Cluster SQL nodes and API nodes. For detailed descriptions and
other additional information about each of these parameters, see *Note
mysql-cluster-api-definition::.

*Note*:

For a discussion of MySQL server options for MySQL Cluster, see *Note
mysql-cluster-mysqld-command-options::; for information about MySQL
server system variables relating to MySQL Cluster, see *Note
mysql-cluster-system-variables::.

_*Restart Type* Column Values_

   * `N': Node Restart

   * `IN': Initial Node Restart

   * `S': System Restart

   * `IS': Initial System Restart

See *Note mysql-cluster-config-params-overview::, for additional
explanations of these abbreviations.

*Parameter Name*       *Type/Units*                         *Default       *Minimum       *Maximum       *Restart Type*
                                                            Value*         Value*         Value*         
`ArbitrationDelay'     milliseconds                         0              0              4294967039     N
`ArbitrationRank'      integer                              0              0              2              N
`BatchByteSize'        bytes                                32K            1K             1M             N
`BatchSize'            integer                              64             1              992            N
`ExecuteOnComputer'    integer                                                                           
`HostName'             string                               _none_         N/A            N/A            IN
`Id'                   integer                              _None_         1              63             IN
`MaxScanBatchSize'     bytes                                256K           32K            16M            N


File: manual.info,  Node: mysql-cluster-config-lcp-params,  Prev: mysql-cluster-config-params-overview,  Up: mysql-cluster-configuration

20.3.6 Configuring Parameters for Local Checkpoints
---------------------------------------------------

The parameters discussed in Logging and Checkpointing and in Data
Memory, Index Memory, and String Memory that are used to configure
local checkpoints for a MySQL Cluster do not exist in isolation, but
rather are very much interdepedent on each other.  In this section, we
illustrate how these parameters -- including `DataMemory',
`IndexMemory', `NoOfDiskPagesToDiskAfterRestartTUP',
`NoOfDiskPagesToDiskAfterRestartACC', and `NoOfFragmentLogFiles' --
relate to one another in a working Cluster.

*Important*:

The parameters `NoOfDiskPagesToDiskAfterRestartTUP' and
`NoOfDiskPagesToDiskAfterRestartACC' were deprecated in MySQL 5.1.6.
From MySQL 5.1.6 through 5.1.11, disk writes during LCPs took place at
the maximum speed possible.  Beginning with MySQL 5.1.12, the speed and
throughput for LCPs are controlled using the parameters `DiskSyncSize',
`DiskCheckpointSpeed', and `DiskCheckpointSpeedInRestart'. See *Note
mysql-cluster-ndbd-definition::.

In this example, we assume that our application performs the following
numbers of types of operations per hour:

   * 50000 selects

   * 15000 inserts

   * 15000 updates

   * 15000 deletes

We also make the following assumptions about the data used in the
application:

   * We are working with a single table having 40 columns.

   * Each column can hold up to 32 bytes of data.

   * A typical `UPDATE' run by the application affects the values of 5
     columns.

   * No `NULL' values are inserted by the application.

A good starting point is to determine the amount of time that should
elapse between local checkpoints (LCPs). It worth noting that, in the
event of a system restart, it takes 40-60 percent of this interval to
execute the REDO log -- for example, if the time between LCPs is 5
minutes (300 seconds), then it should take 2 to 3 minutes (120 to 180
seconds) for the REDO log to be read.

The maximum amount of data per node can be assumed to be the size of
the `DataMemory' parameter. In this example, we assume that this is 2
GB. The `NoOfDiskPagesToDiskAfterRestartTUP' parameter represents the
amount of data to be checkpointed per unit time -- however, this
parameter is actually expressed as the number of 8K memory pages to be
checkpointed per 100 milliseconds.  2 GB per 300 seconds is
approximately 6.8 MB per second, or 700 KB per 100 milliseconds, which
works out to roughly 85 pages per 100 milliseconds.

Similarly, we can calculate `NoOfDiskPagesToDiskAfterRestartACC' in
terms of the time for local checkpoints and the amount of memory
required for indexes -- that is, the `IndexMemory'.  Assuming that we
allow 512 MB for indexes, this works out to approximately 20 8-KB pages
per 100 milliseconds for this parameter.

Next, we need to determine the number of REDO log files required --
that is, fragment log files -- the corresponding parameter being
`NoOfFragmentLogFiles'. We need to make sure that there are sufficient
REDO log files for keeping records for at least 3 local checkpoints. In
a production setting, there are always uncertainties -- for instance,
we cannot be sure that disks always operate at top speed or with maximum
throughput. For this reason, it is best to err on the side of caution,
so we double our requirement and calculate a number of fragment log
files which should be enough to keep records covering 6 local
checkpoints.

It is also important to remember that the disk also handles writes to
the REDO log, so if you find that the amount of data being written to
disk as detemined by the values of `NoOfDiskPagesToDiskAfterRestartACC'
and `NoOfDiskPagesToDiskAfterRestartTUP' is approaching the amount of
disk bandwidth available, you may wish to increase the time between
local checkpoints.

Given 5 minutes (300 seconds) per local checkpoint, this means that we
need to support writing log records at maximum speed for 6 * 300 = 1800
seconds. The size of a REDO log record is 72 bytes plus 4 bytes per
updated column value plus the maximum size of the updated column, and
there is one REDO log record for each table record updated in a
transaction, on each node where the data reside. Using the numbers of
operations set out previously in this section, we derive the following:

   * 50000 select operations per hour yields 0 log records (and thus 0
     bytes), since `SELECT' statements are not recorded in the REDO log.

   * 15000 `DELETE' statements per hour is approximately 5 delete
     operations per second. (Since we wish to be conservative in our
     estimate, we round up here and in the following calculations.) No
     columns are updated by deletes, so these statements consume only 5
     operations * 72 bytes per operation = 360 bytes per second.

   * 15000 `UPDATE' statements per hour is roughly the same as 5
     updates per second. Each update uses 72 bytes, plus 4 bytes per
     column * 5 columns updated, plus 32 bytes per column * 5 columns
     -- this works out to 72 + 20 + 160 = 252 bytes per operation, and
     multiplying this by 5 operation per second yields 1260 bytes per
     second.

   * 15000 `INSERT' statements per hour is equivalent to 5 insert
     operations per second. Each insert requires REDO log space of 72
     bytes, plus 4 bytes per record * 40 columns, plus 32 bytes per
     column * 40 columns, which is 72 + 160 + 1280 = 1512 bytes per
     operation. This times 5 operations per second yields 7560 bytes
     per second.

So the total number of REDO log bytes being written per second is
approximately 0 + 360 + 1260 + 7560 = 9180 bytes. Multiplied by 1800
seconds, this yields 16524000 bytes required for REDO logging, or
approximately 15.75 MB. The unit used for `NoOfFragmentLogFiles'
represents a set of 4 16-MB log files -- that is, 64 MB. Thus, the
minimum value (3) for this parameter is sufficient for the scenario
envisioned in this example, since 3 times 64 = 192 MB, or about 12
times what is required; the default value of 8 (or 512 MB) is more than
ample in this case.


File: manual.info,  Node: mysql-cluster-options-variables,  Next: mysql-cluster-upgrade-downgrade,  Prev: mysql-cluster-configuration,  Up: mysql-cluster

20.4 MySQL Cluster Options and Variables
========================================

* Menu:

* mysql-cluster-option-tables::  MySQL Cluster Server Option and Variable Reference
* mysql-cluster-mysqld-command-options::  MySQL Cluster-Related Command Options for `mysqld'
* mysql-cluster-system-variables::  MySQL Cluster System Variables
* mysql-cluster-status-variables::  MySQL Cluster Status Variables

This section provides information about MySQL server options, server
and status variables that are specific to MySQL Cluster. For general
information on using these, and for other options and variables not
specific to MySQL Cluster, see *Note mysqld-server::.

For MySQL Cluster configuration parameters used in the cluster
configuration file (usually named `config.ini'), see *Note
mysql-cluster-configuration::.


File: manual.info,  Node: mysql-cluster-option-tables,  Next: mysql-cluster-mysqld-command-options,  Prev: mysql-cluster-options-variables,  Up: mysql-cluster-options-variables

20.4.1 MySQL Cluster Server Option and Variable Reference
---------------------------------------------------------

The following table provides a list of the command-line options, server
and status variables applicable within `mysqld' when it is running as
an SQL node in a MySQL Cluster. For a table showing _all_ command-line
options, server and status variables available for use with `mysqld',
see *Note mysqld-option-tables::.

*Name*                        *Cmd-Line*                                                 *Option file*                                              *System Var*                                               *Status Var*                                               *Var Scope*                                                *Dynamic*
Handler_discover                                                                                                                                                                                               Yes                                                        Both                                                       No
have_ndbcluster                                                                                                                                     Yes                                                                                                                   Global                                                     No
ndb_autoincrement_prefetch_sz Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
ndb_cache_check_time          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
ndbcluster                    Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
ndb-cluster-connection-pool   Yes                                                        Yes                                                                                                                   Yes                                                        Global                                                     No
Ndb_cluster_node_id                                                                                                                                                                                            Yes                                                        Both                                                       No
Ndb_config_from_host                                                                                                                                                                                           Yes                                                        Both                                                       No
Ndb_config_from_port                                                                                                                                                                                           Yes                                                        Both                                                       No
Ndb_conflict_fn_max                                                                                                                                                                                            Yes                                                        Both                                                       No
Ndb_conflict_fn_old                                                                                                                                                                                            Yes                                                        Both                                                       No
ndb-connectstring             Yes                                                        Yes                                                                                                                                                                                                                                         
ndb_execute_count                                                                                                                                                                                              Yes                                                        Global                                                     No
ndb_extra_logging             Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
ndb_force_send                Yes                                                        Yes                                                        Yes                                                                                                                   Both                                                       Yes
ndb_index_stat_cache_entries  Yes                                                        Yes                                                                                                                                                                                                                                         
ndb_index_stat_enable         Yes                                                        Yes                                                                                                                                                                                                                                         
ndb_index_stat_update_freq    Yes                                                        Yes                                                                                                                                                                                                                                         
*Note ndb_log_orig:                                                                                                                                 Yes                                                                                                                   Global                                                     No
mysql-cluster-replication-schema.                                                                                                                                                                                                                                                                                                       
ndb_log_update_as_write       Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
ndb_log_updated_only          Yes                                                        Yes                                                        Yes                                                                                                                   Global                                                     Yes
Ndb_number_of_data_nodes                                                                                                                                                                                       Yes                                                        Both                                                       No
ndb_optimized_node_selection  Yes                                                        Yes                                                                                                                                                                                                                                         
ndb_report_thresh_binlog_epoch_slipYes                                                        Yes                                                                                                                                                                                                                                         
ndb_report_thresh_binlog_mem_usageYes                                                        Yes                                                                                                                                                                                                                                         
ndb_use_copying_alter_table                                                                                                                         Yes                                                                                                                   Both                                                       No
ndb_use_exact_count                                                                                                                                 Yes                                                                                                                   Both                                                       Yes
ndb_use_transactions          Yes                                                        Yes                                                                                                                                                                                                                                         
ndb_wait_connected            Yes                                                        Yes                                                        Yes                                                                                                                                                                              No
skip-ndbcluster               Yes                                                        Yes                                                                                                                                                                                                                                         
*Note slave-allow-batching:   Yes                                                                                                                                                                                                                                         Global                                                     Yes
mysql-cluster-replication-starting.                                                                                                                                                                                                                                                                                                       
- _Variable_:                                                                                                                                       Yes                                                                                                                   Global                                                     Yes
slave_allow_batching                                                                                                                                                                                                                                                                                                                 


File: manual.info,  Node: mysql-cluster-mysqld-command-options,  Next: mysql-cluster-system-variables,  Prev: mysql-cluster-option-tables,  Up: mysql-cluster-options-variables

20.4.2 MySQL Cluster-Related Command Options for `mysqld'
---------------------------------------------------------

This section provides descriptions of `mysqld' server options relating
to MySQL Cluster. For information about `mysqld' options not specific
to MySQL Cluster, and for general information about the use of options
with `mysqld', see *Note server-options::.

For information about command-line options used with other MySQL
Cluster processes (`ndbd', `ndb_mgmd', and `ndb_mgm'), see *Note
mysql-cluster-command-options::. For information about command-line
options used with `NDB' utility programs (such as `ndb_desc',
`ndb_size.pl', and `ndb_show_tables'), see *Note
mysql-cluster-utilities::.

   *  `--ndb-cluster-connection-pool=#'

     By setting this option to a value greater than 1 (the default), a
     `mysqld' process can use multiple connections to the cluster,
     effectively mimicking several SQL nodes. Each connection requires
     its own `[api]' or `[mysqld]' section in the cluster configuration
     (`config.ini') file, and counts against the maximum number of API
     connections supported by the cluster.  For example, suppose that
     you have 2 cluster host computers, each running an SQL node whose
     `mysqld' process was started with
     `--ndb-cluster-connection-pool=4'; this means that the cluster
     must have 8 API slots available for these connections (instead of
     2). All of these connections are set up when the SQL node connects
     to the cluster, and are allocated to threads in a round-robin
     fashion.

     *Important*:

     This option is useful only when running `mysqld' on host machines
     having multiple CPUs, multiple cores, or both. For best results,
     the value should be smaller than the total number of cores
     available on the host machine. Setting it to a value greater than
     this is likely to degrade performance severely.

     Beginning with MySQL Cluster NDB 6.2.16 and MySQL Cluster NDB
     6.3.13, the value used for this option is available as a global
     status variable. (Bug#35573 (http://bugs.mysql.com/35573))

   *  `--ndb-connectstring=CONNECT_STRING'

     When using the `NDBCLUSTER' storage engine, this option specifies
     the management server that distributes cluster configuration data.

   *  `--ndbcluster'

     The `NDB' (or `NDBCLUSTER') storage engine is necessary for using
     MySQL Cluster. If a `mysqld' binary includes support for the `NDB'
     storage engine, the engine is disabled by default. Use the
     `--ndbcluster' option to enable it. Use `--skip-ndbcluster' to
     explicitly disable the engine.

   *  `--skip-ndbcluster'

     Disable the `NDB' storage engine. This is the default for binaries
     that were built with `NDB' storage engine support; the server
     allocates memory and other resources for this storage engine only
     if the `--ndbcluster' option is given explicitly. See *Note
     mysql-cluster-quick::, for an example of usage.


File: manual.info,  Node: mysql-cluster-system-variables,  Next: mysql-cluster-status-variables,  Prev: mysql-cluster-mysqld-command-options,  Up: mysql-cluster-options-variables

20.4.3 MySQL Cluster System Variables
-------------------------------------

This section provides detailed information about MySQL server system
variables that are specific to MySQL Cluster and the `NDB' storage
engine. For system variables not specific to MySQL Cluster, see *Note
server-system-variables::. For general information on using system
variables, see *Note using-system-variables::.

   *  `have_ndbcluster'

     *Variable Name*      `have_ndbcluster'
     *Variable Scope*     Global
     *Dynamic Variable*   No
     *Value Set *         
     Typeboolean          

     `YES' if `mysqld' supports `NDB' tables. `DISABLED' if
     `--skip-ndbcluster' is used.

   *  `multi_range_count'

     *Option Sets         Yes, `multi_range_count'
     Variable*            
     *Variable Name*      `multi_range_count'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric          
     Default256           
     Range1-4294967295    

     The maximum number of ranges to send to a table handler at once
     during range selects. The default value is 256. Sending multiple
     ranges to a handler at once can improve the performance of certain
     selects dramatically. This is especially true for the `NDB' table
     handler, which needs to send the range requests to all nodes.
     Sending a batch of those requests at once reduces communication
     costs significantly.

     This variable is deprecated in MySQL 5.1, and is no longer
     supported in MySQL 6.0, in which arbitrarily long lists of ranges
     can be processed.

   *  `ndb_autoincrement_prefetch_sz'

     *Option Sets         Yes, `ndb_autoincrement_prefetch_sz'
     Variable*            
     *Variable Name*      `ndb_autoincrement_prefetch_sz'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set (<=       
     5.1.22)*             
     Typenumeric          
     Default32 Range1-256 
     *Value Set (>=       
     5.1.23)*             
     Typenumeric          
     Default1 Range1-256  

     Determines the probability of gaps in an autoincremented column.
     Set it to `1' to minimize this.  Setting it to a high value for
     optimization -- makes inserts faster, but decreases the likelihood
     that consecutive autoincrement numbers will be used in a batch of
     inserts.  Default value: `32'. Minimum value: `1'.

     Beginning with MySQL Cluster NDB 6.2.10, MySQL Cluster NDB 6.3.7,
     and MySQL 5.1.23, this variable affects the number of
     `AUTO_INCREMENT' IDs that are fetched between statements only.
     Within a statement, at least 32 IDs are now obtained at a time.
     The default value for `ndb_autoincrement_prefetch_sz' is now `1',
     to increase the speed of statements inserting single rows.
     (Bug#31956 (http://bugs.mysql.com/31956))

   *  `ndb_cache_check_time'

     *Option Sets         Yes, `ndb_cache_check_time'
     Variable*            
     *Variable Name*      `ndb_cache_check_time'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric Default0 

     The number of milliseconds that elapse between checks of MySQL
     Cluster SQL nodes by the MySQL query cache. Setting this to 0 (the
     default and minimum value) means that the query cache checks for
     validation on every query.

     The recommended maximum value for this variable is 1000, which
     means that the check is performed once per second. A larger value
     means that the check is performed and possibly invalidated due to
     updates on different SQL nodes less often.  It is generally not
     desirable to set this to a value greater than 2000.

   *  `ndb_extra_logging'

     *Version Introduced* 5.1.6
     *Variable Name*      `ndb_extra_logging'
     *Variable Scope*     Global
     *Dynamic Variable*   Yes
     *Value Set *         
     Typenumeric Default0 

     This variable can be used to enable recording in the MySQL error
     log of information specific to the `NDB' storage engine. It is
     normally of interest only when debugging `NDB' storage engine code.

     The default value is 0, which means that the only `NDB'-specific
     information written to the MySQL error log relates to transaction
     handling. If the value is greater than 0 but less than 10, `NDB'
     table schema and connection events are also logged, as well as
     whether or not conflict resolution is in use, and other `NDB'
     errors and information. If the value is set to 10 or more,
     information about `NDB' internals, such as the progress of data
     distribution among cluster nodes, is also written to the MySQL
     error log.

     This variable was added in MySQL 5.1.6.

   *  `ndb_force_send'

     *Option Sets         Yes, `ndb_force_send'
     Variable*            
     *Variable Name*      `ndb_force_send'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultTRUE          

     Forces sending of buffers to `NDB' immediately, without waiting
     for other threads. Defaults to `ON'.

   *  `ndb_index_stat_cache_entries'

     *Value Set *         
     Typenumeric          
     Default32            
     Range0-4294967295    

     Sets the granularity of the statistics by determining the number
     of starting and ending keys to store in the statistics memory
     cache. Zero means no caching takes place; in this case, the data
     nodes are always queried directly. Default value: `32'.

   *  `ndb_index_stat_enable'

     *Value Set *         
     Typeboolean          
     DefaultON            

     Use `NDB' index statistics in query optimization. Defaults to `ON'.

   *  `ndb_index_stat_update_freq'

     *Value Set *         
     Typenumeric          
     Default20            
     Range0-4294967295    

     How often to query data nodes instead of the statistics cache.
     For example, a value of `20' (the default) means to direct every
     20^th query to the data nodes.

   *  `ndb_optimized_node_selection'

     *Value Set *         
     Typeboolean          
     DefaultON            

     Causes an SQL node to use a data node on the same host machine as
     transaction coordinator. Enabled by default. Set to `0' or `OFF'
     to disable, in which case the SQL node uses each data node in the
     cluster in succession. When this option is disabled, or if there
     is no data node process running on the same host as the SQL node,
     the SQL node attempts to use a given data node 8 times before
     proceeding to the next one.

     Begiunning with MySQL Cluster NDB 6.3.4, this option takes one of
     the integer values `0', `1', `2', or `3', with `1' being the
     default. These values affect node selection as follows:

        * `0': Each data node is employed as the transaction
          coordinator 8 times before the SQL node proceeds to the next
          data node. (This is the same behavior as caused by setting
          this option to `0' or `OFF' in previous MySQL versions.)

        * `1': If a data node process is running on the the same host
          as the SQL node, this data node is used as the transaction
          coordinator. (This is the same behavior as caused by setting
          this option to `1' or `ON' in previous MySQL versions.)

        * `2': The SQL node follows the same behavior as if this option
          had been set to `1'; however, the setting is global.

        * `3': The data node housing the cluster partition accessed by
          the first statement of a given transaction is used as the
          transaction coordinator for the entire transaction. This is
          effective only if the first statement of the transaction
          accesses no more than one cluster partition; otherwise, the
          SQL node reverts to the round-robin behavior seen when this
          option is set to `0'.

     *Important*:

     Beginning with MySQL Cluster NDB 6.3.4, it is no longer possible
     to set `--ndb_optimized_node_selection' to `ON' or `OFF';
     attempting to do so causes `mysqld' to abort with an error.

   *  `ndb_report_thresh_binlog_epoch_slip'

     *Value Set *         
     Typenumeric          
     Default3 Range0-256  

     This is a threshold on the number of epochs to be behind before
     reporting binlog status. For example, a value of `3' (the default)
     means that if the difference between which epoch has been received
     from the storage nodes and which epoch has been applied to the
     binlog is 3 or more, a status message will be sent to the cluster
     log.

   *  `ndb_report_thresh_binlog_mem_usage'

     *Value Set *         
     Typenumeric          
     Default10 Range0-10  

     This is a threshold on the percentage of free memory remaining
     before reporting binlog status. For example, a value of `10' (the
     default) means that if the amount of available memory for
     receiving binlog data from the data nodes falls below 10%, a
     status message will be sent to the cluster log.

   *  `ndb_use_copying_alter_table'

     *Version Introduced* 5.1.12
     *Variable Name*      `ndb_use_copying_alter_table'
     *Variable Scope*     Both
     *Dynamic Variable*   No

     Forces `NDB' to use copying of tables in the event of problems
     with online `ALTER TABLE' operations. The default value is `OFF'.

     This variable was added in MySQL 5.1.12.

   *  `ndb_use_exact_count'

     *Variable Name*      `ndb_use_exact_count'
     *Variable Scope*     Both
     *Dynamic Variable*   Yes
     *Value Set *         
     Typeboolean          
     DefaultON            

     Forces `NDB' to use a count of records during `SELECT COUNT(*)'
     query planning to speed up this type of query. The default value is
     `ON'. For faster queries overall, disable this feature by setting
     the value of `ndb_use_exact_count' to `OFF'.

   *  `ndb_use_transactions'

     *Value Set *         
     Typeboolean          
     DefaultON            

     You can disable `NDB' transaction support by setting this
     variable's values to `OFF' (not recommended). The default is `ON'.

   *  `ndb_wait_connected'

     *Version Introduced* 5.1.16-ndb-6.2.0
     *Option Sets         Yes, `ndb_wait_connected'
     Variable*            
     *Variable Name*      `ndb_wait_connected'
     *Variable Scope*     
     *Dynamic Variable*   No
     *Value Set *         
     Typenumeric Default0 

     This variable can be used to cause the MySQL server to wait a
     given period of time for connections to MySQL Cluster management
     and data nodes to be established before accepting MySQL client
     connections. The time is specified in seconds.  The default value
     is `0'.


File: manual.info,  Node: mysql-cluster-status-variables,  Prev: mysql-cluster-system-variables,  Up: mysql-cluster-options-variables

20.4.4 MySQL Cluster Status Variables
-------------------------------------

This section provides detailed information about MySQL server status
variables that relate to MySQL Cluster and the `NDB' storage engine.
For status variables not specific to MySQL Cluster, and for general
information on using status variables, see *Note
server-status-variables::.

   *  `Handler_discover'

     The MySQL server can ask the `NDBCLUSTER' storage engine if it
     knows about a table with a given name.  This is called discovery.
     `Handler_discover' indicates the number of times that tables have
     been discovered via this mechanism.

   *  `Ndb_cluster_node_id'

     If the server is acting as a MySQL Cluster node, then the value of
     this variable its node ID in the cluster.

     If the server is not part of a MySQL Cluster, then the value of
     this variable is 0.

   *  `Ndb_config_from_host'

     If the server is part of a MySQL Cluster, the value of this
     variable is the hostname or IP address of the Cluster management
     server from which it gets its configuration data.

     If the server is not part of a MySQL Cluster, then the value of
     this variable is an empty string.

     Prior to MySQL 5.1.12, this variable was named
     `Ndb_connected_host'.

   *  `Ndb_config_from_port'

     If the server is part of a MySQL Cluster, the value of this
     variable is the number of the port through which it is connected
     to the Cluster management server from which it gets its
     configuration data.

     If the server is not part of a MySQL Cluster, then the value of
     this variable is 0.

     Prior to MySQL 5.1.12, this variable was named
     `Ndb_connected_port'.

   *  `Ndb_execute_count'

     Provides the number of round trips to the `NDB' kernel made by
     operations. Added in MySQL Cluster NDB 6.3.6.

   *  `Ndb_number_of_data_nodes'

     If the server is part of a MySQL Cluster, the value of this
     variable is the number of data nodes in the cluster.

     If the server is not part of a MySQL Cluster, then the value of
     this variable is 0.

     Prior to MySQL 5.1.12, this variable was named
     `Ndb_number_of_storage_nodes'.

   *  `Slave_heartbeat_period'

     Shows the replication heartbeat interval (in seconds) on a
     replication slave.

     This variable was added in MySQL Cluster NDB 6.3.4.

   *  `Slave_received_heartbeats'

     This counter increments with each replication heartbeat received
     by a replication slave since the last time that the slave was
     restarted or reset, or a `CHANGE MASTER' statement was issued.

     This variable was added in MySQL Cluster NDB 6.3.4.


File: manual.info,  Node: mysql-cluster-upgrade-downgrade,  Next: mysql-cluster-process-management,  Prev: mysql-cluster-options-variables,  Up: mysql-cluster

20.5 Upgrading and Downgrading MySQL Cluster
============================================

* Menu:

* mysql-cluster-rolling-restart::  Performing a Rolling Restart of the Cluster
* mysql-cluster-upgrade-downgrade-compatibility::  MySQL Cluster 5.1 and MySQL Cluster NDB 6.x Upgrade and Downgrade Compatibility

This portion of the MySQL Cluster chapter covers upgrading and
downgrading a MySQL Cluster from one MySQL release to another. It
discusses different types of Cluster upgrades and downgrades, and
provides a Cluster upgrade/downgrade compatibility matrix (see *Note
mysql-cluster-upgrade-downgrade-compatibility::).  You are expected
already to be familiar with installing and configuring a MySQL Cluster
prior to attempting an upgrade or downgrade. See *Note
mysql-cluster-configuration::.

For information about upgrading or downgrading between MySQL Cluster
NDB releases, or between MySQL Cluster NDB releases and mainline MySQL
releases, see the changelogs relating to MySQL Cluster NDB.

This section remains in development, and continues to be updated and
expanded.


File: manual.info,  Node: mysql-cluster-rolling-restart,  Next: mysql-cluster-upgrade-downgrade-compatibility,  Prev: mysql-cluster-upgrade-downgrade,  Up: mysql-cluster-upgrade-downgrade

20.5.1 Performing a Rolling Restart of the Cluster
--------------------------------------------------

This section discusses how to perform a _rolling restart_ of a MySQL
Cluster installation, so called because it involves stopping and
starting (or restarting) each node in turn, so that the cluster itself
remains operational. This is often done as part of a _rolling upgrade_
or _rolling downgrade_, where high availability of the cluster is
mandatory and no downtime of the cluster as a whole is permissible.
Where we refer to upgrades, the information provided here also
generally applies to downgrades as well.

There are a number of reasons why a rolling restart might be desirable:

   * Cluster configuration change

     To make a change in the cluster's configuration, such as adding an
     SQL node to the cluster, or setting a configuration parameter to a
     new value.

   * Cluster software upgrade/downgrade

     To upgrade the cluster to a newer version of the MySQL Cluster
     software (or to downgrade it to an older version).  This is
     usually referred to as a `rolling upgrade' (or `rolling
     downgrade', when reverting to an older version of MySQL Cluster).

   * Change on node host

     To make changes in the hardware or operating system on which one
     or more cluster nodes are running

   * Cluster reset

     To reset the cluster because it has reached an undesirable state

   * Freeing of resources

     To allow memory allocated to a table by successive `INSERT' and
     `DELETE' operations to be freed for re-use by other Cluster tables

The process for performing a rolling restart may be generalised as
follows:

  1. Stop all cluster management nodes (`ndb_mgmd' processes),
     reconfigure them, then restart them

  2. Stop, reconfigure, then restart each cluster data node (`ndbd'
     process) in turn

  3. Stop, reconfigure, then restart each cluster SQL node (`mysqld'
     process) in turn

The specifics for implementing a particular rolling upgrade depend upon
the actual changes being made. A more detailed view of the process is
presented here:

MySQL Cluster Rolling Restarts (By Type)

In the previous diagram, *Stop* and *Start* steps indicate that the
process must be stopped completely using a shell command (such as
`kill' on most Unix systems) or the management client `STOP' command,
then started again from a system shell by invoking the `ndbd' or
`ndb_mgmd' executable as appropriate.  *Restart* indicates the process
may be restarted using the `ndb_mgm' management client `RESTART'
command.

*Important*:

When performing an upgrade or downgrade of the cluster software, you
_must_ upgrade or downgrade the management nodes _first_, then the data
nodes, and finally the SQL nodes. Doing so in any other order may leave
the cluster in an unusable state.


File: manual.info,  Node: mysql-cluster-upgrade-downgrade-compatibility,  Prev: mysql-cluster-rolling-restart,  Up: mysql-cluster-upgrade-downgrade

20.5.2 MySQL Cluster 5.1 and MySQL Cluster NDB 6.x Upgrade and Downgrade Compatibility
--------------------------------------------------------------------------------------

This section provides information about MySQL Cluster software and
table file compatibility between MySQL 5.1 and MySQL Cluster NDB 6.x
releases with regard to performing upgrades and downgrades.

*Important*:

Only compatibility between MySQL versions with regard to `NDBCLUSTER'
is taken into account in this section, and there are likely other
issues to be considered.  _As with any other MySQL software upgrade or
downgrade, you are strongly encouraged to review the relevant portions
of the MySQL Manual for the MySQL versions from which and to which you
intend to migrate, before attempting an upgrade or downgrade of the
MySQL Cluster software_. See *Note upgrade::.

The following table shows Cluster upgrade and downgrade compatibility
between different releases of MySQL 5.1:

MySQL Cluster upgrade/downgrade compatibility, MySQL 5.1

Notes -- MySQL 5.1

   * MySQL 5.1.3 was the first public release in this series.

   * Direct upgrades or downgrades between MySQL Cluster 5.0 and 5.1
     are not supported; you must dump all `NDBCLUSTER' tables using
     `mysqldump', install the new version of the software, and then
     reload the tables from the dump.

   * You cannot downgrade a MySQL 5.1.6 or later Cluster using Disk
     Data tables to MySQL 5.1.5 or earlier unless you convert all such
     tables to in-memory Cluster tables first.

   * MySQL 5.1.8, MySQL 5.1.10, and MySQL 5.1.13 were not released.

   * Online cluster upgrades and downgrades between MySQL 5.1.11 (or an
     earlier version) and 5.1.12 (or a later version) are not possible
     due to major changes in the cluster filesystem. In such cases, you
     must perform a backup or dump, upgrade (or downgrade) the
     software, start each data node with `--initial', and then restore
     from the backup or dump. You can use `NDB' backup/restore or
     `mysqldump' for this purpose.

   * Online downgrades from MySQL 5.1.14 or later to versions previous
     to 5.1.14 are not supported due to incompatible changes in the
     cluster system tables.

   * Online upgrades from MySQL 5.1.17 and earlier to 5.1.18 and later
     are not supported for clusters using replication due to
     incompatible changes in the `mysql.ndb_apply_status' table.
     However, it should not be necessary to shut down the cluster
     entirely, if you follow this modified rolling restart procedure:

       1. Stop the management server, update the `ndb_mgmd' binary,
          then start it again. For multiple management servers, repeat
          this step for each management server in turn.

       2. For each data node in turn: Stop the data node, replace the
          `ndbd' binary with the new version, then restart the data
          node. It is not necessary to use `--initial' when restarting
          any of the data nodes.

       3. Stop _all_ SQL nodes. Replace the `mysqld' binary with the new
          version for all SQL nodes, then restart them. It is not
          necessary to start them one at a time, but they must all be
          shut down at the same time before starting any of them again
          using the 5.1.18 (or later) `mysqld'. Otherwise -- due to the
          fact that `mysql.ndb_apply_status' uses the `NDB' storage
          engine and is thus shared between all SQL nodes -- there may
          be conflicts between MySQL servers using the old and new
          versions of the table.

     You can find more information about the changes to
     `ndb_apply_status' in *Note mysql-cluster-replication-schema::.

   *  The internal specifications for columns in `NDB' tables changed
     in MySQL 5.1.18 to allow compatibility with future MySQL Cluster
     releases that are expected to implement online adding and dropping
     of columns. This change is not backwards compatible with earlier
     MySQL versions.

     In order to make tables created in MySQL 5.1.17 and earlier
     compatible with online adding and dropping of columns when this
     features becomes available, it is necessary force MySQL 5.1.18 and
     later to convert the tables to the new format by following this
     procedure:

       1. Upgrade the MySQL Cluster software on all data, management,
          and SQL nodes

       2. Back up all `NDB' tables

       3. Shut down the cluster (all data, management, and SQL nodes)

       4. Restart the cluster, starting all data nodes with the
          `--initial' option (to clear and rebuild the data node
          filesystems)

       5. Restore the tables from backup

     This is not necessary for `NDB' tables created in MySQL 5.1.18 and
     later; such tables will automatically be compatible with online
     adding and dropping of columns (as implemented beginning with MySQL
     Cluster NDB 6.2.5 and MySQL Cluster NDB 6.3.2).

     In order to minimise possible later difficulties, it is strongly
     advised that the procedure outlined above be followed as soon as
     possible after to upgrading from MySQL 5.1.17 or earlier to MySQL
     5.1.18 or later.

     Information about how this change effects users of MySQL Cluster
     NDB 6.x is provided later in this section.

   * MySQL Cluster is not supported in standard MySQL 5.1 releases,
     beginning with MySQL 5.1.25. If you are using MySQL Cluster in a
     standard MySQL 5.1 release, you should upgrade to the most recent
     MySQL Cluster NDB 6.2 or 6.3 release.

The following table shows Cluster upgrade and downgrade compatibility
between different releases of MySQL Cluster NDB 6.x:

MySQL Cluster upgrade/downgrade compatibility, MySQL Cluster NDB 6.x

Notes -- MySQL Cluster NDB 6.x

   * MySQL Cluster NDB 6.1 is no longer in production; if you are still
     using a MySQL Cluster NDB 6.1 release, you should upgrade to the
     most recent MySQL Cluster NDB 6.2 or 6.3 as soon as possible.

   * It is not possible to upgrade from MySQL Cluster NDB 6.1.2 (or an
     older 6.1 release) directly to 6.1.4 or a newer NDB 6.1 release,
     or to downgrade from 6.1.4 (or a newer 6.1 release) directly to
     6.1.2 or an older NDB 6.1 release; in either case, you must
     upgrade or downgrade to MySQL Cluster NDB 6.1.3 first.

   * It is not possible to perform an online downgrade from MySQL
     Cluster NDB 6.1.8 (or a newer 6.1 release) to MySQL Cluster NDB
     6.1.7 (or an older 6.1 release).

   * MySQL Cluster NDB 6.1.6 and 6.1.18 were not released.

   * It is not possible to perform an online upgrade or downgrade
     between MySQL Cluster NDB 6.2 and any previous release series
     (including mainline MySQL 5.1 and MySQL Cluster NDB 6.1); it is
     necessary to perform a dump and reload. However, it should be
     possible to perform online upgrades or downgrades between any
     MySQL Cluster NDB 6.2 release and any MySQL Cluster NDB 6.3
     release up to and including 6.3.7.

   *  The internal specifications for columns in `NDB' tables changed
     in MySQL Cluster NDB 6.1.17 and 6.2.1 to allow compatibility with
     future MySQL Cluster releases that are expected to implement online
     adding and dropping of columns. This change is not backwards
     compatible with earlier MySQL or MySQL Cluster NDB 6.x versions.

     In order to make tables created in earlier versions compatible
     with online adding and dropping of columns in later versions, it
     is necessary to force MySQL Cluster to convert the tables to the
     new format by following this procedure following an upgrade:

       1. Upgrade the MySQL Cluster software on all data, management,
          and SQL nodes

       2. Back up all `NDB' tables

       3. Shut down the cluster (all data, management, and SQL nodes)

       4. Restart the cluster, starting all data nodes with the
          `--initial' option (to clear and rebuild the data node
          filesystems)

       5. Restore the tables from backup

     In order to minimise possible later difficulties, it is strongly
     advised that the procedure outlined above be followed as soon as
     possible after to upgrading between the versions indicated. The
     procedure is _not_ necessary for `NDBCLUSTER' tables created in
     any of the following versions:

        * MySQL Cluster NDB 6.1.8 or a later MySQL Cluster NDB 6.1
          release

        * MySQL Cluster 6.2.1 or a later MySQL Cluster NDB 6.2 release

        * Any MySQL Cluster NDB 6.3 release

     Tables created in the listed versions (or later ones, as
     indicated) are already compatible with online adding and dropping
     of columns (as implemented beginning with MySQL Cluster NDB 6.2.5
     and MySQL Cluster NDB 6.3.2).

   * Online downgrades between MySQL Cluster NDB 6.3.8 and earlier
     releases are not supported.


File: manual.info,  Node: mysql-cluster-process-management,  Next: mysql-cluster-management,  Prev: mysql-cluster-upgrade-downgrade,  Up: mysql-cluster

20.6 Process Management in MySQL Cluster
========================================

* Menu:

* mysql-cluster-mysqld-process::  MySQL Server Process Usage for MySQL Cluster
* mysql-cluster-ndbd-process::   `ndbd' --- The Storage Engine Node Process
* mysql-cluster-ndb-mgmd-process::  `ndb_mgmd' --- The Management Server Process
* mysql-cluster-ndb-mgm-process::  `ndb_mgm' --- The Management Client Process
* mysql-cluster-command-options::  Command Options for MySQL Cluster Processes

Understanding how to manage MySQL Cluster requires a knowledge of four
essential processes. In the next few sections of this chapter, we cover
the roles played by these processes in a cluster, how to use them, and
what startup options are available for each of them:

   * *Note mysql-cluster-mysqld-process::

   * *Note mysql-cluster-ndbd-process::

   * *Note mysql-cluster-ndb-mgmd-process::

   * *Note mysql-cluster-ndb-mgm-process::


File: manual.info,  Node: mysql-cluster-mysqld-process,  Next: mysql-cluster-ndbd-process,  Prev: mysql-cluster-process-management,  Up: mysql-cluster-process-management

20.6.1 MySQL Server Process Usage for MySQL Cluster
---------------------------------------------------

`mysqld' is the traditional MySQL server process.  To be used with
MySQL Cluster, `mysqld' needs to be built with support for the
`NDBCLUSTER' storage engine, as it is in the precompiled binaries
available from `http://dev.mysql.com/downloads/'. If you build MySQL
from source, you must invoke `configure' with the `--with-ndbcluster'
option to enable `NDB Cluster' storage engine support.

If the `mysqld' binary has been built with Cluster support, the
`NDBCLUSTER' storage engine is still disabled by default. You can use
either of two possible options to enable this engine:

   * Use `--ndbcluster' as a startup option on the command line when
     starting `mysqld'.

   * Insert a line containing `ndbcluster' in the `[mysqld]' section of
     your `my.cnf' file.

An easy way to verify that your server is running with the `NDBCLUSTER'
storage engine enabled is to issue the `SHOW ENGINES' statement in the
MySQL Monitor (`mysql'). You should see the value `YES' as the
`Support' value in the row for `NDBCLUSTER'. If you see `NO' in this
row or if there is no such row displayed in the output, you are not
running an `NDB'-enabled version of MySQL. If you see `DISABLED' in
this row, you need to enable it in either one of the two ways just
described.

To read cluster configuration data, the MySQL server requires at a
minimum three pieces of information:

   * The MySQL server's own cluster node ID

   * The hostname or IP address for the management server (MGM node)

   * The number of the TCP/IP port on which it can connect to the
     management server

Node IDs can be allocated dynamically, so it is not strictly necessary
to specify them explicitly.

The `mysqld' parameter `ndb-connectstring' is used to specify the
connectstring either on the command line when starting `mysqld' or in
`my.cnf'. The connectstring contains the hostname or IP address where
the management server can be found, as well as the TCP/IP port it uses.

In the following example, `ndb_mgmd.mysql.com' is the host where the
management server resides, and the management server listens for
cluster messages on port 1186:

     shell> mysqld --ndbcluster --ndb-connectstring=ndb_mgmd.mysql.com:1186

See *Note mysql-cluster-connectstring::, for more information on
connectstrings.

Given this information, the MySQL server will be a full participant in
the cluster. (We often refer to a `mysqld' process running in this
manner as an SQL node.) It will be fully aware of all cluster data
nodes as well as their status, and will establish connections to all
data nodes. In this case, it is able to use any data node as a
transaction coordinator and to read and update node data.

You can see in the `mysql' client whether a MySQL server is connected
to the cluster using `SHOW PROCESSLIST'. If the MySQL server is
connected to the cluster, and you have the `PROCESS' privilege, then
the first row of the output is as shown here:

     mysql> SHOW PROCESSLIST \G
     *************************** 1. row ***************************
          Id: 1
        User: system user
        Host:
          db:
     Command: Daemon
        Time: 1
       State: Waiting for event from ndbcluster
        Info: NULL

*Important*:

To participate in a MySQL Cluster, the `mysqld' process must be started
with _both_ the options `--ndbcluster' and `--ndb-connectstring' (or
their equivalents in `my.cnf'). If `mysqld' is started with only the
`--ndbcluster' option, or if it is unable to contact the cluster, it is
not possible to work with `NDB' tables, _nor is it possible to create
any new tables regardless of storage engine_. The latter restriction is
a safety measure intended to prevent the creation of tables having the
same names as `NDB' tables while the SQL node is not connected to the
cluster. If you wish to create tables using a different storage engine
while the `mysqld' process is not participating in a MySQL Cluster, you
must restart the server _without_ the `--ndbcluster' option.


File: manual.info,  Node: mysql-cluster-ndbd-process,  Next: mysql-cluster-ndb-mgmd-process,  Prev: mysql-cluster-mysqld-process,  Up: mysql-cluster-process-management

20.6.2 `ndbd' -- The Storage Engine Node Process
------------------------------------------------

`ndbd' is the process that is used to handle all the data in tables
using the NDB Cluster storage engine.  This is the process that
empowers a data node to accomplish distributed transaction handling,
node recovery, checkpointing to disk, online backup, and related tasks.

In a MySQL Cluster, a set of `ndbd' processes cooperate in handling
data. These processes can execute on the same computer (host) or on
different computers. The correspondences between data nodes and Cluster
hosts is completely configurable.

`ndbd' generates a set of log files which are placed in the directory
specified by `DataDir' in the `config.ini' configuration file.

These log files are listed below.  NODE_ID is the node's unique
identifier. Note that NODE_ID represents the node's unique identifier.
For example, `ndb_2_error.log' is the error log generated by the data
node whose node ID is `2'.

   * `ndb_NODE_ID_error.log' is a file containing records of all
     crashes which the referenced `ndbd' process has encountered. Each
     record in this file contains a brief error string and a reference
     to a trace file for this crash. A typical entry in this file might
     appear as shown here:

          Date/Time: Saturday 30 July 2004 - 00:20:01
          Type of error: error
          Message: Internal program error (failed ndbrequire)
          Fault ID: 2341
          Problem data: DbtupFixAlloc.cpp
          Object of reference: DBTUP (Line: 173)
          ProgramName: NDB Kernel
          ProcessID: 14909
          TraceFile: ndb_2_trace.log.2
          ***EOM***

     Listings of possible `ndbd' exit codes and messages generated when
     a data node process shuts down prematurely can be found in `ndbd'
     Error Messages
     (http://dev.mysql.com/doc/ndbapi/en/ndbd-error-messages.html).

     *Important*:

     _The last entry in the error log file is not necessarily the
     newest one_ (nor is it likely to be). Entries in the error log are
     _not_ listed in chronological order; rather, they correspond to
     the order of the trace files as determined in the
     `ndb_NODE_ID_trace.log.next' file (see below). Error log entries
     are thus overwritten in a cyclical and not sequential fashion.

   * `ndb_NODE_ID_trace.log.TRACE_ID' is a trace file describing
     exactly what happened just before the error occurred. This
     information is useful for analysis by the MySQL Cluster
     development team.

     It is possible to configure the number of these trace files that
     will be created before old files are overwritten. TRACE_ID is a
     number which is incremented for each successive trace file.

   * `ndb_NODE_ID_trace.log.next' is the file that keeps track of the
     next trace file number to be assigned.

   * `ndb_NODE_ID_out.log' is a file containing any data output by the
     `ndbd' process. This file is created only if `ndbd' is started as
     a daemon, which is the default behavior.

   * `ndb_NODE_ID.pid' is a file containing the process ID of the
     `ndbd' process when started as a daemon.  It also functions as a
     lock file to avoid the starting of nodes with the same identifier.

   * `ndb_NODE_ID_signal.log' is a file used only in debug versions of
     `ndbd', where it is possible to trace all incoming, outgoing, and
     internal messages with their data in the `ndbd' process.

It is recommended not to use a directory mounted through NFS because in
some environments this can cause problems whereby the lock on the
`.pid' file remains in effect even after the process has terminated.

To start `ndbd', it may also be necessary to specify the hostname of
the management server and the port on which it is listening.
Optionally, one may also specify the node ID that the process is to use.

     shell> ndbd --connect-string="nodeid=2;host=ndb_mgmd.mysql.com:1186"

See *Note mysql-cluster-connectstring::, for additional information
about this issue.  *Note mysql-cluster-command-options::, describes
other options for `ndbd'.

When `ndbd' starts, it actually initiates two processes. The first of
these is called the `angel process'; its only job is to discover when
the execution process has been completed, and then to restart the
`ndbd' process if it is configured to do so.  Thus, if you attempt to
kill `ndbd' via the Unix `kill' command, it is necessary to kill both
processes, beginning with the angel process. The preferred method of
terminating an `ndbd' process is to use the management client and stop
the process from there.

The execution process uses one thread for reading, writing, and
scanning data, as well as all other activities. This thread is
implemented asynchronously so that it can easily handle thousands of
concurrent activites. In addition, a watch-dog thread supervises the
execution thread to make sure that it does not hang in an endless loop.
A pool of threads handles file I/O, with each thread able to handle one
open file. Threads can also be used for transporter connections by the
transporters in the `ndbd' process. In a multi-processor system
performing a large number of operations (including updates), the `ndbd'
process can consume up to 2 CPUs if permitted to do so.

For a machine with many CPUs it is possible to use several `ndbd'
processes which belong to different node groups; however, such a
configuration is still considered experimental and is not supported for
MySQL 5.1 in a production setting. See *Note
mysql-cluster-limitations::.


File: manual.info,  Node: mysql-cluster-ndb-mgmd-process,  Next: mysql-cluster-ndb-mgm-process,  Prev: mysql-cluster-ndbd-process,  Up: mysql-cluster-process-management

20.6.3 `ndb_mgmd' -- The Management Server Process
--------------------------------------------------

The management server is the process that reads the cluster
configuration file and distributes this information to all nodes in the
cluster that request it. It also maintains a log of cluster activities.
Management clients can connect to the management server and check the
cluster's status.

It is not strictly necessary to specify a connectstring when starting
the management server. However, if you are using more than one
management server, a connectstring should be provided and each node in
the cluster should specify its node ID explicitly.

See *Note mysql-cluster-connectstring::, for information about using
connectstrings.  *Note mysql-cluster-command-options::, describes other
options for `ndb_mgmd'.

The following files are created or used by `ndb_mgmd' in its starting
directory, and are placed in the `DataDir' as specified in the
`config.ini' configuration file. In the list that follows, NODE_ID is
the unique node identifier.

   * `config.ini' is the configuration file for the cluster as a whole.
     This file is created by the user and read by the management server.
     *Note mysql-cluster-configuration::, discusses how to set up this
     file.

   * `ndb_NODE_ID_cluster.log' is the cluster events log file. Examples
     of such events include checkpoint startup and completion, node
     startup events, node failures, and levels of memory usage. A
     complete listing of cluster events with descriptions may be found
     in *Note mysql-cluster-management::.

     When the size of the cluster log reaches one million bytes, the
     file is renamed to `ndb_NODE_ID_cluster.log.SEQ_ID', where SEQ_ID
     is the sequence number of the cluster log file. (For example: If
     files with the sequence numbers 1, 2, and 3 already exist, the
     next log file is named using the number `4'.)

   * `ndb_NODE_ID_out.log' is the file used for `stdout' and `stderr'
     when running the management server as a daemon.

   * `ndb_NODE_ID.pid' is the process ID file used when running the
     management server as a daemon.


File: manual.info,  Node: mysql-cluster-ndb-mgm-process,  Next: mysql-cluster-command-options,  Prev: mysql-cluster-ndb-mgmd-process,  Up: mysql-cluster-process-management

20.6.4 `ndb_mgm' -- The Management Client Process
-------------------------------------------------

The `ndb_mgm' management client process is actually not needed to run
the cluster. Its value lies in providing a set of commands for checking
the cluster's status, starting backups, and performing other
administrative functions. The management client accesses the management
server using a C API. Advanced users can also employ this API for
programming dedicated management processes to perform tasks similar to
those performed by `ndb_mgm'.

To start the management client, it is necessary to supply the hostname
and port number of the management server:

     shell> ndb_mgm [HOST_NAME [PORT_NUM]]

For example:

     shell> ndb_mgm ndb_mgmd.mysql.com 1186

The default hostname and port number are `localhost' and 1186,
respectively.

Additional information about using `ndb_mgm' can be found in *Note
mysql-cluster-ndb-mgm-command-options::, and *Note
mysql-cluster-mgm-client-commands::.


File: manual.info,  Node: mysql-cluster-command-options,  Prev: mysql-cluster-ndb-mgm-process,  Up: mysql-cluster-process-management

20.6.5 Command Options for MySQL Cluster Processes
--------------------------------------------------

* Menu:

* mysql-cluster-ndbd-command-options::  Command Options for `ndbd'
* mysql-cluster-ndb-mgmd-command-options::  Command Options for `ndb_mgmd'
* mysql-cluster-ndb-mgm-command-options::  Command Options for `ndb_mgm'

All MySQL Cluster executables (except for `mysqld') take the options
described in this section. Users of earlier MySQL Cluster versions
should note that some of these options have been changed to make them
consistent with one another as well as with `mysqld'. You can use the
`--help' option with any MySQL Cluster executable to view a list of the
options which it supports.

The following options are common to all MySQL Cluster executables:

   * `--help' `--usage', `-?'

     Prints a short list with descriptions of the available command
     options.

   * `--connect-string=CONNECT_STRING', `-c CONNECT_STRING'

     CONNECT_STRING sets the connectstring to the management server as
     a command option.

          shell> ndbd --connect-string="nodeid=2;host=ndb_mgmd.mysql.com:1186"

     For more information, see *Note mysql-cluster-connectstring::.

   * `--debug[=OPTIONS]'

     This option can be used only for versions compiled with debugging
     enabled. It is used to enable output from debug calls in the same
     manner as for the `mysqld' process.

   * `--execute=`command'', `-e `command''

     Can be used to send a command to a Cluster executable from the
     system shell. For example, either of the following:

          shell> ndb_mgm -e "SHOW"

     or

          shell> ndb_mgm --execute="SHOW"

     is equivalent to

          ndb_mgm> SHOW

     This is analogous to how the `--execute' or `-e' option works with
     the `mysql' command-line client. See *Note command-line-options::.

   * `--version', `-V'

     Prints the MySQL Cluster version number of the executable. The
     version number is relevant because not all versions can be used
     together, and the MySQL Cluster startup process verifies that the
     versions of the binaries being used can co-exist in the same
     cluster. This is also important when performing an online
     (rolling) software upgrade or downgrade of MySQL Cluster. (See
     *Note mysql-cluster-rolling-restart::).

The next few sections describe options specific to individual `NDB'
programs.

See *Note mysql-cluster-mysqld-command-options::, for `mysqld' options
relating to MySQL Cluster.


File: manual.info,  Node: mysql-cluster-ndbd-command-options,  Next: mysql-cluster-ndb-mgmd-command-options,  Prev: mysql-cluster-command-options,  Up: mysql-cluster-command-options

20.6.5.1 Command Options for `ndbd'
...................................

For options common to all `NDB' programs, see *Note
mysql-cluster-command-options::.

   * `--bind-address'

     Causes `ndbd' to bind to a specific network interface (hostname or
     IP address). This option has no default value.

     This option was added in MySQL 5.1.12.

   * `--daemon', `-d'

     Instructs `ndbd' to execute as a daemon process. This is the
     default behavior.  `--nodaemon' can be used to prevent the process
     from running as a daemon.

   * `--initial'

     Instructs `ndbd' to perform an initial start. An initial start
     erases any files created for recovery purposes by earlier
     instances of `ndbd'. It also re-creates recovery log files. Note
     that on some operating systems this process can take a substantial
     amount of time.

     An `--initial' start is to be used _only_ when starting the `ndbd'
     process under very special circumstances; this is because this
     option causes all files to be removed from the Cluster filesystem
     and all redo log files to be re-created. These circumstances are
     listed here:

        * When performing a software upgrade which has changed the
          contents of any files.

        * When restarting the node with a new version of `ndbd'.

        * As a measure of last resort when for some reason the node
          restart or system restart repeatedly fails. In this case, be
          aware that this node can no longer be used to restore data
          due to the destruction of the data files.

     *Important*:

     This option does _not_ affect either of the following:

        * Backup files that have already been created by the affected
          node

        * Cluster Disk Data files (see *Note mysql-cluster-disk-data::).

     It is permissible to use this option when starting the cluster for
     the very first time (that is, before any data node files have been
     created); however, it is _not_ necessary to do so.

   * `--initial-start'

     This option is used when performing a partial initial start of the
     cluster. Each node should be started with this option, as well as
     `--nowait-nodes'.

     For example, suppose you have a 4-node cluster whose data nodes
     have the IDs 2, 3, 4, and 5, and you wish to perform a partial
     initial start using only nodes 2, 4, and 5 -- that is, omitting
     node 3:

          ndbd --ndbd-nodeid=2 --nowait-nodes=3 --initial-start
          ndbd --ndbd-nodeid=4 --nowait-nodes=3 --initial-start
          ndbd --ndbd-nodeid=5 --nowait-nodes=3 --initial-start

     This option was added in MySQL 5.1.11.

     *Important*:

     Prior to MySQL 5.1.19, it was not possible to perform DDL
     operations involving Disk Data tables on a partially started
     cluster. (See Bug#24631 (http://bugs.mysql.com/24631).)

   * `--nowait-nodes=NODE_ID_1[, NODE_ID_2[, ...]]'

     This option takes a list of data nodes which for which the cluster
     will not wait for before starting.

     This can be used to start the cluster in a partitioned state. For
     example, to start the cluster with only half of the data nodes
     (nodes 2, 3, 4, and 5) running in a 4-node cluster, you can start
     each `ndbd' process with `--nowait-nodes=3,5'. In this case, the
     cluster starts as soon as nodes 2 and 4 connect, and does _not_
     wait `StartPartitionedTimeout' milliseconds for nodes 3 and 5 to
     connect as it would otherwise.

     If you wanted to start up the same cluster as in the previous
     example without one `ndbd' -- say, for example, that the host
     machine for node 3 has suffered a hardware failure -- then start
     nodes 2, 4, and 5 with `--nowait-nodes=3'. Then the cluster will
     start as soon as nodes 2, 4, and 5 connect and will not wait for
     node 3 to start.

     This option was added in MySQL 5.1.9.

   * `--nodaemon'

     Instructs `ndbd' not to start as a daemon process. This is useful
     when `ndbd' is being debugged and you want output to be redirected
     to the screen.

   * `--nostart', `-n'

     Instructs `ndbd' not to start automatically. When this option is
     used, `ndbd' connects to the management server, obtains
     configuration data from it, and initializes communication objects.
     However, it does not actually start the execution engine until
     specifically requested to do so by the management server. This can
     be accomplished by issuing the proper `START' command in the
     management client (see *Note mysql-cluster-mgm-client-commands::).


File: manual.info,  Node: mysql-cluster-ndb-mgmd-command-options,  Next: mysql-cluster-ndb-mgm-command-options,  Prev: mysql-cluster-ndbd-command-options,  Up: mysql-cluster-command-options

20.6.5.2 Command Options for `ndb_mgmd'
.......................................

For options common to NDB programs, see *Note
mysql-cluster-command-options::.

   * `--bind-address=HOST[:PORT]'

     When specified, this option limits management server connections
     by management clients to clients at the specified hostname or IP
     address (and possibly port, if this is also specified). In such
     cases, a management client attempting to connect to the management
     server from any other address fails with the error `Unable to
     setup port: HOST:PORT!'

     If the PORT is not specified, the management client attempts to
     use port 1186.

     This option was added in MySQL Cluster NDB 6.2.5 and MySQL Cluster
     NDB 6.3.2.

   * `--config-file=FILENAME', `-f FILENAME'

     Instructs the management server as to which file it should use for
     its configuration file. By default, the management server looks
     for a file named `config.ini' in the same directory as the
     `ndb_mgmd' executable; otherwise the filename and location must be
     specified explicitly.

   * `--daemon', `-d'

     Instructs `ndb_mgmd' to start as a daemon process. This is the
     default behavior.

   * `--nodaemon'

     Instructs `ndb_mgmd' not to start as a daemon process.

   * `--print-full-config', `-P'

     Shows extended information regarding the configuration of the
     cluster. With this option on the command line the `ndb_mgmd'
     process prints information about the cluster setup including an
     extensive list of the cluster configuration sections as well as
     parameters and their values. Normally used together with the
     `--config-file' (`-f') option.


File: manual.info,  Node: mysql-cluster-ndb-mgm-command-options,  Prev: mysql-cluster-ndb-mgmd-command-options,  Up: mysql-cluster-command-options

20.6.5.3 Command Options for `ndb_mgm'
......................................

For options common to NDB programs, see *Note
mysql-cluster-command-options::.

   * `--try-reconnect=NUMBER'

     If the connection to the management server is broken, the node
     tries to reconnect to it every 5 seconds until it succeeds. By
     using this option, it is possible to limit the number of attempts
     to NUMBER before giving up and reporting an error instead.


File: manual.info,  Node: mysql-cluster-management,  Next: mysql-cluster-security,  Prev: mysql-cluster-process-management,  Up: mysql-cluster

20.7 Management of MySQL Cluster
================================

* Menu:

* mysql-cluster-start-phases::   Summary of MySQL Cluster Start Phases
* mysql-cluster-mgm-client-commands::  Commands in the MySQL Cluster Management Client
* mysql-cluster-event-reports::  Event Reports Generated in MySQL Cluster
* mysql-cluster-logs-ndb-messages::  `NDB' Log Messages
* mysql-cluster-single-user-mode::  Single User Mode
* mysql-cluster-sql-statements::  Quick Reference: MySQL Cluster SQL Statements

Managing a MySQL Cluster involves a number of tasks, the first of which
is to configure and start MySQL Cluster. This is covered in *Note
mysql-cluster-configuration::, and *Note
mysql-cluster-process-management::.

The following sections cover the management of a running MySQL Cluster.

For information about security issues relating to management and
deployment of a MySQL Cluster, see *Note mysql-cluster-security::.

There are essentially two methods of actively managing a running MySQL
Cluster. The first of these is through the use of commands entered into
the management client whereby cluster status can be checked, log levels
changed, backups started and stopped, and nodes stopped and started.
The second method involves studying the contents of the cluster log
`ndb_NODE_ID_cluster.log'; this is usually found in the management
server's `DataDir' directory, but this location can be overridden using
the `LogDestination' option -- see *Note
mysql-cluster-mgm-definition::, for details. (Recall that NODE_ID
represents the unique identifier of the node whose activity is being
logged.)  The cluster log contains event reports generated by `ndbd'.
It is also possible to send cluster log entries to a Unix system log.

In addition, some aspects of the cluster's operation can be monitored
from an SQL node using the `SHOW ENGINE NDB STATUS' statement. See
*Note show-engine::, for more information.


File: manual.info,  Node: mysql-cluster-start-phases,  Next: mysql-cluster-mgm-client-commands,  Prev: mysql-cluster-management,  Up: mysql-cluster-management

20.7.1 Summary of MySQL Cluster Start Phases
--------------------------------------------

This section provides a simplified outline of the steps involved when
MySQL Cluster data nodes are started. More complete information can be
found in MySQL Cluster Start Phases
(http://dev.mysql.com/doc/ndbapi/en/ndb-internals-start-phases.html).

These phases are the same as those reported in the output from the
`NODE_ID STATUS' command in the management client. (See *Note
mysql-cluster-mgm-client-commands::, for more information about this
command.)

Start types

There are several different startup types and modes, as shown here:

   * Initial Start

     The cluster starts with a clean filesystem on all data nodes. This
     occurs either when the cluster started for the very first time, or
     when all data nodes are restarted using the `--initial' option.

     *Note*:

     Disk Data files are not removed when restarting a node using
     `--initial'.

   * System Restart

     The cluster starts and reads data stored in the data nodes. This
     occurs when the cluster has been shut down after having been in
     use, when it is desired for the cluster to resume operations from
     the point where it left off.

   * Node Restart

     This is the online restart of a cluster node while the cluster
     itself is running.

   * Initial Node Restart

     This is the same as a node restart, except that the node is
     reinitialized and started with a clean filesystem.

Setup and initialization (Phase -1)

Prior to startup, each data node (`ndbd' process) must be initialized.
Initialization consists of the following steps:

  1. Obtain a node ID

  2. Fetch configuration data

  3. Allocate ports to be used for inter-node communications

  4. Allocate memory according to settings obtained from the
     configuration file

When a data node or SQL node first connects to the management node, it
reserves a cluster node ID. To make sure that no other node allocates
the same node ID, this ID is retained until the node has managed to
connect to the cluster and at least one `ndbd' reports that this node
is connected. This retention of the node ID is guarded by the
connection between the node in question and `ndb_mgmd'.

Normally, in the event of a problem with the node, the node disconnects
from the management server, the socket used for the connection is
closed, and the reserved node ID is freed. However, if a node is
disconnected abruptly -- for example, due to a hardware failure in one
of the cluster hosts, or because of network issues -- the normal
closing of the socket by the operating system may not take place. In
this case, the node ID continues to be reserved and not released until
a TCP timeout occurs 10 or so minutes later.

To take care of this problem, you can use `PURGE STALE SESSIONS'.
Running this statement forces all reserved node IDs to be checked; any
that are not being used by nodes actually connected to the cluster are
then freed.

Beginning with MySQL 5.1.11, timeout handling of node ID assignments is
implemented. This performs the ID usage checks automatically after
approximately 20 seconds, so that `PURGE STALE SESSIONS' should no
longer be necessary in a normal Cluster start.

After each data node has been initialized, the cluster startup process
can proceed. The stages which the cluster goes through during this
process are listed here:

   * Phase 0

     The `NDBFS' and `NDBCNTR' blocks start (see `NDB' Kernel Blocks
     (http://dev.mysql.com/doc/ndbapi/en/ndb-internals-kernel-blocks.html)).
     The cluster filesystem is cleared, if the cluster was started with
     the `--initial' option.

   * Phase 1

     In this stage, all remaining `NDB' kernel blocks are started.
     Cluster connections are set up, inter-block communications are
     established, and Cluster heartbeats are started. In the case of a
     node restart, API node connections are also checked.

     *Note*:

     When one or more nodes hang in Phase 1 while the remaining node or
     nodes hang in Phase 2, this often indicates network problems. One
     possible cause of such issues is one or more cluster hosts having
     multiple network interfaces. Another common source of problems
     causing this condition is the blocking of TCP/IP ports needed for
     communications between cluster nodes. In the latter case, this is
     often due to a misconfigured firewall.

   * Phase 2

     The `NDBCNTR' kernel block checks the states of all existing
     nodes. The master node is chosen, and the cluster schema file is
     initialized.

   * Phase 3

     The `DBLQH' and `DBTC' kernel blocks set up communications between
     them. The startup type is determined; if this is a restart, the
     `DBDIH' block obtains permission to perform the restart.

   * Phase 4

     For an initial start or initial node restart, the redo log files
     are created. The number of these files is equal to
     `NoOfFragmentLogFiles'.

     For a system restart:

        * Read schema or schemas.

        * Read data from the local checkpoint.

        * Apply all redo information until the latest restorable global
          checkpoint has been reached.

     For a node restart, find the tail of the redo log.

   * Phase 5

     Most of the database-related portion of a data node start is
     performed during this phase. For an initial start or system
     restart, a local checkpoint is executed, followed by a global
     checkpoint. Periodic checks of memory usage begin during this
     phase, and any required node takeovers are performed.

   * Phase 6

     In this phase, node groups are defined and set up.

   * Phase 7

     The arbitrator node is selected and begins to function.  The next
     backup ID is set, as is the backup disk write speed. Nodes
     reaching this start phase are marked as `Started'. It is now
     possible for API nodes (including SQL nodes) to connect to the
     cluster.  connect.

   * Phase 8

     If this is a system restart, all indexes are rebuilt (by `DBDIH').

   * Phase 9

     The node internal startup variables are reset.

   * Phase 100 (_OBSOLETE_)

     Formerly, it was at this point during a node restart or initial
     node restart that API nodes could connect to the node and begin to
     receive events. Currently, this phase is empty.

   * Phase 101

     At this point in a node restart or initial node restart, event
     delivery is handed over to the node joining the cluster. The
     newly-joined node takes over responsibility for delivering its
     primary data to subscribers. This phase is also referred to as
     _`SUMA' handover phase_.

After this process is completed for an initial start or system restart,
transaction handling is enabled. For a node restart or initial node
restart, completion of the startup process means that the node may now
act as a transaction coordinator.


File: manual.info,  Node: mysql-cluster-mgm-client-commands,  Next: mysql-cluster-event-reports,  Prev: mysql-cluster-start-phases,  Up: mysql-cluster-management

20.7.2 Commands in the MySQL Cluster Management Client
------------------------------------------------------

In addition to the central configuration file, a cluster may also be
controlled through a command-line interface available through the
management client `ndb_mgm'. This is the primary administrative
interface to a running cluster.

Commands for the event logs are given in *Note
mysql-cluster-event-reports::; commands for creating backups and
restoring from backup are provided in *Note mysql-cluster-backup::.

The management client has the following basic commands. In the listing
that follows, NODE_ID denotes either a database node ID or the keyword
`ALL', which indicates that the command should be applied to all of the
cluster's data nodes.

   * `HELP'

     Displays information on all available commands.

   * `SHOW'

     Displays information on the cluster's status.

     *Note*:

     In a cluster where multiple management nodes are in use, this
     command displays information only for data nodes that are actually
     connected to the current management server.

   * `NODE_ID START'

     Brings online the data node identified by NODE_ID (or all data
     nodes).

     `ALL START' works on all data nodes only, and does not affect
     management nodes.

     *Important*:

     To use this command to bring a data node online, the data node
     must have been started using `ndbd --nostart' or `ndbd -n'.

   * `NODE_ID STOP'

     Stops the data or management node identified by NODE_ID. Note that
     `ALL STOP' works to stop all data nodes only, and does not affect
     management nodes.

     A node affected by this command disconnects from the cluster, and
     its associated `ndbd' or `ndb_mgmd' process terminates.

   * `NODE_ID RESTART [-n] [-i] [-a]'

     Restarts the data node identified by NODE_ID (or all data nodes).

     Using the `-i' option with `RESTART' causes the data node to
     perform an initial restart; that is, the node's filesystem is
     deleted and recreated. The effect is the same as that obtained from
     stopping the data node process and then starting it again using
     `ndbd --initial' from the system shell.  Note that backup files
     and Disk Data files are not removed when this option is used.

     Using the `-n' option causes the data node process to be
     restarted, but the data node is not actually brought online until
     the appropriate `START' command is issued. The effect of this
     option is the same as that obtained from stopping the data node
     and then starting it again using `ndbd --nostart' or `ndbd -n'
     from the system shell.

     Using the `-a' causes all current transactions relying on this
     node to be aborted. No GCP check is done when the node rejoins the
     cluster.

   * `NODE_ID STATUS'

     Displays status information for the data node identified by
     NODE_ID (or for all data nodes).

   * `NODE_ID REPORT REPORT-TYPE'

     Displays a report of type REPORT-TYPE for the data node identified
     by NODE_ID, or for all data nodes using `ALL'.

     Currently, there are two accepted values for REPORT-TYPE:

        * `BackupStatus' provides a status report on a cluster backup
          in progress

        * `MemoryUsage' displays how much data memory and index memory
          is being used by each data node.

     The `REPORT' command was introduced in MySQL Cluster NDB 6.2.3 and
     MySQL Cluster NDB 6.3.0.

   * `ENTER SINGLE USER MODE NODE_ID'

     Enters single user mode, whereby only the MySQL server identified
     by the node ID NODE_ID is allowed to access the database.

     *Important*:

     It is not possible in MySQL 5.1 for data nodes to join the cluster
     while it is running in single user mode.  (See Bug#20395
     (http://bugs.mysql.com/20395) for more information.)

   * `EXIT SINGLE USER MODE'

     Exits single user mode, allowing all SQL nodes (that is, all
     running `mysqld' processes) to access the database.

   * `QUIT', `EXIT'

     Terminates the management client.

     This command does not affect any nodes connected to the cluster.

   * `SHUTDOWN'

     Shuts down all cluster data nodes and management nodes. To exit
     the management client after this has been done, use `EXIT' or
     `QUIT'.

     This command does _not_ shut down any SQL nodes or API nodes that
     are connected to the cluster.


File: manual.info,  Node: mysql-cluster-event-reports,  Next: mysql-cluster-logs-ndb-messages,  Prev: mysql-cluster-mgm-client-commands,  Up: mysql-cluster-management

20.7.3 Event Reports Generated in MySQL Cluster
-----------------------------------------------

* Menu:

* mysql-cluster-logging-management-commands::  Logging Management Commands
* mysql-cluster-log-events::     Log Events
* mysql-cluster-log-statistics::  Using `CLUSTERLOG STATISTICS'

In this section, we discuss the types of event logs provided by MySQL
Cluster, and the types of events that are logged.

MySQL Cluster provides two types of event log:

   * The _cluster log_, which includes events generated by all cluster
     nodes. The cluster log is the log recommended for most uses
     because it provides logging information for an entire cluster in a
     single location.

     By default, the cluster log is saved to a file named
     `ndb_NODE_ID_cluster.log', (where NODE_ID is the node ID of the
     management server) in the same directory where the `ndb_mgm'
     binary resides.

     Cluster logging information can also be sent to `stdout' or a
     `syslog' facility in addition to or instead of being saved to a
     file, as determined by the values set for the `DataDir' and
     `LogDestination' configuration parameters.  See *Note
     mysql-cluster-mgm-definition::, for more information about these
     parameters.

   * _Node logs_ are local to each node.

     Output generated by node event logging is written to the file
     `ndb_NODE_ID_out.log' (where NODE_ID is the node's node ID) in the
     node's `DataDir'. Node event logs are generated for both
     management nodes and data nodes.

     Node logs are intended to be used only during application
     development, or for debugging application code.

Both types of event logs can be set to log different subsets of events.

Each reportable event can be distinguished according to three different
criteria:

   * _Category_: This can be any one of the following values: `STARTUP',
     `SHUTDOWN', `STATISTICS', `CHECKPOINT', `NODERESTART',
     `CONNECTION', `ERROR', or `INFO'.

   * _Priority_: This is represented by one of the numbers from 1 to 15
     inclusive, where 1 indicates `most important' and 15 `least
     important.'

   * _Severity Level_: This can be any one of the following values:
     `ALERT', `CRITICAL', `ERROR', `WARNING', `INFO', or `DEBUG'.

Both the cluster log and the node log can be filtered on these
properties.

The format used in the cluster log is as shown here:

     2007-01-26 19:35:55 [MgmSrvr] INFO     -- Node 1: Data usage is 2%(60 32K pages of total 2560)
     2007-01-26 19:35:55 [MgmSrvr] INFO     -- Node 1: Index usage is 1%(24 8K pages of total 2336)
     2007-01-26 19:35:55 [MgmSrvr] INFO     -- Node 1: Resource 0 min: 0 max: 639 curr: 0
     2007-01-26 19:35:55 [MgmSrvr] INFO     -- Node 2: Data usage is 2%(76 32K pages of total 2560)
     2007-01-26 19:35:55 [MgmSrvr] INFO     -- Node 2: Index usage is 1%(24 8K pages of total 2336)
     2007-01-26 19:35:55 [MgmSrvr] INFO     -- Node 2: Resource 0 min: 0 max: 639 curr: 0
     2007-01-26 19:35:55 [MgmSrvr] INFO     -- Node 3: Data usage is 2%(58 32K pages of total 2560)
     2007-01-26 19:35:55 [MgmSrvr] INFO     -- Node 3: Index usage is 1%(25 8K pages of total 2336)
     2007-01-26 19:35:55 [MgmSrvr] INFO     -- Node 3: Resource 0 min: 0 max: 639 curr: 0
     2007-01-26 19:35:55 [MgmSrvr] INFO     -- Node 4: Data usage is 2%(74 32K pages of total 2560)
     2007-01-26 19:35:55 [MgmSrvr] INFO     -- Node 4: Index usage is 1%(25 8K pages of total 2336)
     2007-01-26 19:35:55 [MgmSrvr] INFO     -- Node 4: Resource 0 min: 0 max: 639 curr: 0
     2007-01-26 19:39:42 [MgmSrvr] INFO     -- Node 4: Node 9 Connected
     2007-01-26 19:39:42 [MgmSrvr] INFO     -- Node 1: Node 9 Connected
     2007-01-26 19:39:42 [MgmSrvr] INFO     -- Node 1: Node 9: API version 5.1.15
     2007-01-26 19:39:42 [MgmSrvr] INFO     -- Node 2: Node 9 Connected
     2007-01-26 19:39:42 [MgmSrvr] INFO     -- Node 2: Node 9: API version 5.1.15
     2007-01-26 19:39:42 [MgmSrvr] INFO     -- Node 3: Node 9 Connected
     2007-01-26 19:39:42 [MgmSrvr] INFO     -- Node 3: Node 9: API version 5.1.15
     2007-01-26 19:39:42 [MgmSrvr] INFO     -- Node 4: Node 9: API version 5.1.15
     2007-01-26 19:59:22 [MgmSrvr] ALERT    -- Node 2: Node 7 Disconnected
     2007-01-26 19:59:22 [MgmSrvr] ALERT    -- Node 2: Node 7 Disconnected

Each line in the cluster log contains the following information:

   * A timestamp in `YYYY-MM-DD HH:MM:SS' format.

   * The type of node which is performing the logging. In the cluster
     log, this is always `[MgmSrvr]'.

   * The severity of the event.

   * The ID of the node reporting the event.

   * A description of the event. The most common types of events to
     appear in the log are connections and disconnections between
     different nodes in the cluster, and when checkpoints occur. In
     some cases, the description may contain status information.


File: manual.info,  Node: mysql-cluster-logging-management-commands,  Next: mysql-cluster-log-events,  Prev: mysql-cluster-event-reports,  Up: mysql-cluster-event-reports

20.7.3.1 Logging Management Commands
....................................

The following management commands are related to the cluster log:

   * `CLUSTERLOG ON'

     Turns the cluster log on.

   * `CLUSTERLOG OFF'

     Turns the cluster log off.

   * `CLUSTERLOG INFO'

     Provides information about cluster log settings.

   * `NODE_ID CLUSTERLOG CATEGORY=THRESHOLD'

     Logs CATEGORY events with priority less than or equal to THRESHOLD
     in the cluster log.

   * `CLUSTERLOG FILTER SEVERITY_LEVEL'

     Toggles cluster logging of events of the specified SEVERITY_LEVEL.

The following table describes the default setting (for all data nodes)
of the cluster log category threshold. If an event has a priority with
a value lower than or equal to the priority threshold, it is reported
in the cluster log.

Note that events are reported per data node, and that the threshold can
be set to different values on different nodes.

*Category*             *Default threshold (All data nodes)*
`STARTUP'              *7*
`SHUTDOWN'             *7*
`STATISTICS'           *7*
`CHECKPOINT'           *7*
`NODERESTART'          *7*
`CONNECTION'           *7*
`ERROR'                *15*
`INFO'                 *7*

The `STATISTICS' category can provide a great deal of useful data. See
*Note mysql-cluster-log-statistics::, for more information.

Thresholds are used to filter events within each category. For example,
a `STARTUP' event with a priority of 3 is not logged unless the
threshold for `STARTUP' is set to 3 or higher. Only events with
priority 3 or lower are sent if the threshold is 3.

The following table shows the event severity levels.

*Note*:

These correspond to Unix `syslog' levels, except for `LOG_EMERG' and
`LOG_NOTICE', which are not used or mapped.

*1*     `ALERT'        A condition that should be corrected immediately,
                       such as a corrupted system database
*2*     `CRITICAL'     Critical conditions, such as device errors or
                       insufficient resources
*3*     `ERROR'        Conditions that should be corrected, such as
                       configuration errors
*4*     `WARNING'      Conditions that are not errors, but that might
                       require special handling
*5*     `INFO'         Informational messages
*6*     `DEBUG'        Debugging messages used for `NDBCLUSTER'
                       development

Event severity levels can be turned on or off (using `CLUSTERLOG
FILTER' -- see above). If a severity level is turned on, then all
events with a priority less than or equal to the category thresholds
are logged. If the severity level is turned off then no events
belonging to that severity level are logged.

*Important*:

Cluster log levels are set on a per `ndb_mgmd', per subscriber basis.
This means that, in a MySQL Cluster with multiple management servers,
using a `CLUSTERLOG' command in an instance of `ndb_mgm' connected to
one management server affects only logs generated by that management
server but not by any of the others. This also means that, should one
of the management servers be restarted, only logs generated by that
management server are affected by the resetting of log levels caused by
the restart.


File: manual.info,  Node: mysql-cluster-log-events,  Next: mysql-cluster-log-statistics,  Prev: mysql-cluster-logging-management-commands,  Up: mysql-cluster-event-reports

20.7.3.2 Log Events
...................

An event report reported in the event logs has the following format:

     DATETIME [STRING] SEVERITY -- MESSAGE

For example:

     09:19:30 2005-07-24 [NDB] INFO -- Node 4 Start phase 4 completed

This section discusses all reportable events, ordered by category and
severity level within each category.

In the event descriptions, GCP and LCP mean `Global Checkpoint' and
`Local Checkpoint', respectively.

*`CONNECTION' Events*

These events are associated with connections between Cluster nodes.

*Event*                   *Priority**Severity*Description*
                                  Level*  
data nodes connected      8       `INFO'  Data nodes connected
data nodes disconnected   8       `INFO'  Data nodes disconnected
Communication closed      8       `INFO'  SQL node or data node
                                          connection closed
Communication opened      8       `INFO'  SQL node or data node
                                          connection opened

*`CHECKPOINT' Events*

The logging messages shown here are associated with checkpoints.

*Event*                   *Priority**Severity*Description*
                                  Level*  
LCP stopped in calc keep  0       `ALERT' LCP stopped
GCI                                       
Local checkpoint          11      `INFO'  LCP on a fragment has been
fragment completed                        completed
Global checkpoint         10      `INFO'  GCP finished
completed                                 
Global checkpoint started 9       `INFO'  Start of GCP: REDO log is
                                          written to disk
Local checkpoint          8       `INFO'  LCP completed normally
completed                                 
Local checkpoint started  7       `INFO'  Start of LCP: data written to
                                          disk

*`STARTUP' Events*

The following events are generated in response to the startup of a node
or of the cluster and of its success or failure. They also provide
information relating to the progress of the startup process, including
information concerning logging activities.

*Event*                   *Priority**Severity*Description*
                                  Level*  
Internal start signal     15      `INFO'  Blocks received after
received STTORRY                          completion of restart
New REDO log started      10      `INFO'  GCI keep X, newest restorable
                                          GCI Y
New log started           10      `INFO'  Log part X, start MB Y, stop MB
                                          Z
Node has been refused     8       `INFO'  Node cannot be included in
for inclusion in the                      cluster due to
cluster                                   misconfiguration, inability to
                                          establish communication, or
                                          other problem
data node neighbors       8       `INFO'  Shows neighboring data nodes
data node start phase X   4       `INFO'  A data node start phase has
completed                                 been completed
Node has been             3       `INFO'  Displays the node, managing
successfully included                     node, and dynamic ID
into the cluster                          
data node start phases    1       `INFO'  NDB Cluster nodes starting
initiated                                 
data node all start       1       `INFO'  NDB Cluster nodes started
phases completed                          
data node shutdown        1       `INFO'  Shutdown of data node has
initiated                                 commenced
data node shutdown        1       `INFO'  Unable to shut down data node
aborted                                   normally

*`NODERESTART' Events*

The following events are generated when restarting a node and relate to
the success or failure of the node restart process.

*Event*                   *Priority**Severity*Description*
                                  Level*  
Node failure phase        8       `ALERT' Reports completion of node
completed                                 failure phases
Node has failed, node     8       `ALERT' Reports that a node has failed
state was X                               
Report arbitrator results 2       `ALERT' There are eight different
                                          possible results for
                                          arbitration attempts:
                                          
                                             * Arbitration check failed
                                               -- less than 1/2 nodes left
                                          
                                             * Arbitration check
                                               succeeded -- node group
                                               majority
                                          
                                             * Arbitration check failed
                                               -- missing node group
                                          
                                             * Network partitioning --
                                               arbitration required
                                          
                                             * Arbitration succeeded --
                                               affirmative response from
                                               node X
                                          
                                             * Arbitration failed -
                                               negative response from node
                                               X
                                          
                                             * Network partitioning - no
                                               arbitrator available
                                          
                                             * Network partitioning - no
                                               arbitrator configured
Completed copying a       10      `INFO'  
fragment                                  
Completed copying of      8       `INFO'  
dictionary information                    
Completed copying         8       `INFO'  
distribution information                  
Starting to copy          8       `INFO'  
fragments                                 
Completed copying all     8       `INFO'  
fragments                                 
GCP takeover started      7       `INFO'  
GCP takeover completed    7       `INFO'  
LCP takeover started      7       `INFO'  
LCP takeover completed    7       `INFO'  
(state = X)                               
Report whether an         6       `INFO'  There are seven different
arbitrator is found or                    possible outcomes when seeking
not                                       an arbitrator:
                                          
                                             * Management server restarts
                                               arbitration thread
                                               [state=X]
                                          
                                             * Prepare arbitrator node X
                                               [ticket=Y]
                                          
                                             * Receive arbitrator node X
                                               [ticket=Y]
                                          
                                             * Started arbitrator node X
                                               [ticket=Y]
                                          
                                             * Lost arbitrator node X -
                                               process failure [state=Y]
                                          
                                             * Lost arbitrator node X -
                                               process exit [state=Y]
                                          
                                             * Lost arbitrator node X
                                               <error msg> [state=Y]
*`STATISTICS' Events*

The following events are of a statistical nature. They provide
information such as numbers of transactions and other operations,
amount of data sent or received by individual nodes, and memory usage.

*Event*                   *Priority**Severity*Description*
                                  Level*  
Report job scheduling     9       `INFO'  Mean internal job scheduling
statistics                                statistics
Sent number of bytes      9       `INFO'  Mean number of bytes sent to
                                          node X
Received # of bytes       9       `INFO'  Mean number of bytes received
                                          from node X
Report transaction        8       `INFO'  Numbers of: transactions,
statistics                                commits, reads, simple reads,
                                          writes, concurrent operations,
                                          attribute information, and
                                          aborts
Report operations         8       `INFO'  Number of operations
Report table create       7       `INFO'  
Memory usage              5       `INFO'  Data and index memory usage
                                          (80%, 90%, and 100%)

*`ERROR' Events*

These events relate to Cluster errors and warnings. The presence of one
or more of these generally indicates that a major malfunction or
failure has occurred.

*Event*                   *Priority**Severity**Description*
Dead due to missed        8       `ALERT' Node X declared `dead' due to
heartbeat                                 missed heartbeat
Transporter errors        2       ERROR   
Transporter warnings      8       `WARNING'
Missed heartbeats         8       `WARNING'Node X missed heartbeat #Y
General warning events    2       `WARNING'

*`INFO' Events*

These events provide general information about the state of the cluster
and activities associated with Cluster maintenance, such as logging and
heartbeat transmission.

*Event*                   *Priority**Severity**Description*
Sent heartbeat            12      `INFO'  Heartbeat sent to node X
Create log bytes          11      `INFO'  Log part, log file, MB
General information       2       `INFO'  
events                                    


File: manual.info,  Node: mysql-cluster-log-statistics,  Prev: mysql-cluster-log-events,  Up: mysql-cluster-event-reports

20.7.3.3 Using `CLUSTERLOG STATISTICS'
......................................

The `NDB' management client's `CLUSTERLOG STATISTICS' command can
provide a number of useful statistics in its output. The following
statistics are reported by the transaction coordinator:

*Statistic*            *Description (_Number of..._)*
`Trans. Count'         Transactions attempted with this node as
                       coordinator
`Commit Count'         Transactions committed with this node as
                       coordinator
`Read Count'           Primary key reads (all)
`Simple Read Count'    Primary key reads reading the latest committed
                       value
`Write Count'          Primary key writes (includes all `INSERT',
                       `UPDATE', and `DELETE' operations)
`AttrInfoCount'        Data words used to describe all reads and writes
                       received
`Concurrent            All concurrent operations ongoing at the moment
Operations'            the report is taken
`Abort Count'          Transactions with this node as coordinator that
                       were aborted
`Scans'                Scans (all)
`Range Scans'          Index scans

The `ndbd' process has a scheduler that runs in an infinite loop.
During each loop scheduler performs the following tasks:

  1. Read any incoming messages from sockets into a job buffer.

  2. Check whether there are any timed messages to be executed; if so,
     put these into the job buffer as well.

  3. Execute (in a loop) any messages in the job buffer.

  4. Send any distributed messages that were generated by executing the
     messages in the job buffer.

  5. Wait for any new incoming messages.

The number of loops executed in the third step is reported as the `Mean
Loop Counter'. This statistic increases in size as the utilisation of
the TCP/IP buffer improves. You can use this to monitor performance as
you add new processes to the cluster.

The `Mean send size' and `Mean receive size' statistics allow you to
gauge the efficiency of writes and reads (respectively) between nodes.
These values are given in bytes. Higher values mean a lower cost per
byte sent or received; the maximum is 64k.

To cause all cluster log statistics to be logged, you can use the
following command in the `NDB' management client:

     ndb_mgm> ALL CLUSTERLOG STATISTICS=15

*Note*:

Setting the threshold for `STATISTICS' to 15 causes the cluster log to
become very verbose, and to gow quite rapidly in size, in direct
proportion to the number of cluster nodes and the amount of activity on
the cluster.


File: manual.info,  Node: mysql-cluster-logs-ndb-messages,  Next: mysql-cluster-single-user-mode,  Prev: mysql-cluster-event-reports,  Up: mysql-cluster-management

20.7.4 `NDB' Log Messages
-------------------------

* Menu:

* mysql-cluster-logs-cluster-log::  Messages in the Cluster Log
* mysql-cluster-ndb-transporter-errors::  `NDB' Transporter Errors

This section contains information about the messages written to the
cluster log in response to different cluster log events. It provides
additional, more specific information on `NDB' transporter errors.


File: manual.info,  Node: mysql-cluster-logs-cluster-log,  Next: mysql-cluster-ndb-transporter-errors,  Prev: mysql-cluster-logs-ndb-messages,  Up: mysql-cluster-logs-ndb-messages

20.7.4.1 Messages in the Cluster Log
....................................

The following table lists the most common `NDB' cluster log messages.
For information about the cluster log, log events, and event types, see
*Note mysql-cluster-event-reports::. These log messages also correspond
to log event types in the MGM API; see The `Ndb_logevent_type' Type
(http://dev.mysql.com/doc/ndbapi/en/ndb-logevent-type.html), for
related information of interest to Cluster API developers.

Log Message                                 Event Name
                                            
`Node MGM_NODE_ID: Node DATA_NODE_ID        `Connected'
Connected'                                  
                                            Event Type
Description                                 
                                            `Connection'
The data node having node ID NODE_ID has    
connected to the management server (node    Priority
MGM_NODE_ID).                               
                                            8
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node MGM_NODE_ID: Node DATA_NODE_ID        `Disconnected'
Disconnected'                               
                                            Event Type
Description                                 
                                            `Connection'
The data node having node ID DATA_NODE_ID   
has disconnected from the management        Priority
server (node MGM_NODE_ID).                  
                                            8
                                            
                                            Severity
                                            
                                            `ALERT'
Log Message                                 Event Name
                                            
`Node DATA_NODE_ID: Communication to Node   `CommunicationClosed'
API_NODE_ID closed'                         
                                            Event Type
Description                                 
                                            `Connection'
The API node or SQL node having node ID     
API_NODE_ID is no longer communicating      Priority
with data node DATA_NODE_ID.                
                                            8
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node DATA_NODE_ID: Communication to Node   `CommunicationOpened'
API_NODE_ID opened'                         
                                            Event Type
Description                                 
                                            `Connection'
The API node or SQL node having node ID     
API_NODE_ID is now communicating with data  Priority
node DATA_NODE_ID.                          
                                            8
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node MGM_NODE_ID: Node API_NODE_ID: API    `ConnectedApiVersion'
VERSION'                                    
                                            Event Type
Description                                 
                                            `Connection'
The API node having node ID API_NODE_ID     
has connected to management node            Priority
MGM_NODE_ID using `NDB' API version         
VERSION (generally the same as the MySQL    8
version number).                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: Global checkpoint GCI        `GlobalCheckpointStarted'
started'                                    
                                            Event Type
Description                                 
                                            `Checkpoint'
A global checkpoint with the ID GCI has     
been started; node NODE_ID is the master    Priority
responsible for this global checkpoint.     
                                            9
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: Global checkpoint GCI        `GlobalCheckpointCompleted'
completed'                                  
                                            Event Type
Description                                 
                                            `Checkpoint'
The global checkpoint having the ID GCI     
has been completed; node NODE_ID was the    Priority
master responsible for this global          
checkpoint.                                 10
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: Local checkpoint LCP         `LocalCheckpointStarted'
started. Keep GCI = CURRENT_GCI oldest      
restorable GCI = OLD_GCI'                   Event Type
                                            
Description                                 `Checkpoint'
                                            
The local checkpoint having sequence ID     Priority
LCP has been started on node NODE_ID. The   
most recent GCI that can be used has the    7
index CURRENT_GCI, and the oldest GCI from  
which the cluster can be restored has the   Severity
index OLD_GCI.                              
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: Local checkpoint LCP         `LocalCheckpointCompleted'
completed'                                  
                                            Event Type
Description                                 
                                            `Checkpoint'
The local checkpoint having sequence ID     
LCP on node NODE_ID has been completed.     Priority
                                            
                                            8
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: Local Checkpoint stopped in  `LCPStoppedInCalcKeepGci'
CALCULATED_KEEP_GCI'                        
                                            Event Type
Description                                 
                                            `Checkpoint'
The node was unable to determine the most   
recent usable GCI.                          Priority
                                            
                                            0
                                            
                                            Severity
                                            
                                            `ALERT'
Log Message                                 Event Name
                                            
`Node NODE_ID: Table ID = TABLE_ID,         `LCPFragmentCompleted'
fragment ID = FRAGMENT_ID has completed     
LCP on Node NODE_ID maxGciStarted:          Event Type
STARTED_GCI maxGciCompleted: COMPLETED_GCI' 
                                            `Checkpoint'
Description                                 
                                            Priority
A table fragment has been checkpointed to   
disk on node NODE_ID. The GCI in progress   11
has the index STARTED_GCI, and the most     
recent GCI to have been completed has the   Severity
index COMPLETED_GCI.                        
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: ACC Blocked NUM_1 and TUP    `UndoLogBlocked'
Blocked NUM_2 times last second'            
                                            Event Type
Description                                 
                                            `Checkpoint'
Undo logging is blocked because the log     
buffer is close to overflowing.             Priority
                                            
                                            7
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: Start initiated VERSION'     `NDBStartStarted'
                                            
Description                                 Event Type
                                            
Data node NODE_ID, running `NDB' version    `StartUp'
VERSION, is beginning its startup process.  
                                            Priority
                                            
                                            1
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: Started VERSION'             `NDBStartCompleted'
                                            
Description                                 Event Type
                                            
Data node NODE_ID, running `NDB' version    `StartUp'
VERSION, has started successfully.          
                                            Priority
                                            
                                            1
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: STTORRY received after       `STTORRYRecieved'
restart finished'                           
                                            Event Type
Description                                 
                                            `StartUp'
The node has received a signal indicating   
that a cluster restart has completed.       Priority
                                            
                                            15
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: Start phase PHASE completed  `StartPhaseCompleted'
(TYPE)'                                     
                                            Event Type
Description                                 
                                            `StartUp'
The node has completed start phase PHASE    
of a TYPE start. For a listing of start     Priority
phases, see *Note                           
mysql-cluster-start-phases::.  (TYPE is     4
one of `initial', `system', `node',         
`initial node', or `<Unknown>'.)            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: CM_REGCONF president =       `CM_REGCONF'
PRESIDENT_ID, own Node = OWN_ID, our        
dynamic id = DYNAMIC_ID'                    Event Type
                                            
Description                                 `StartUp'
                                            
Node PRESIDENT_ID has been selected as      Priority
`president'.  OWN_ID and DYNAMIC_ID should  
always be the same as the ID (NODE_ID) of   3
the reporting node.                         
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: CM_REGREF from Node          `CM_REGREF'
PRESIDENT_ID to our Node NODE_ID. Cause =   
CAUSE'                                      Event Type
                                            
Description                                 `StartUp'
                                            
The reporting node (ID NODE_ID) was unable  Priority
to accept node PRESIDENT_ID as president.   
The CAUSE of the problem is given as one of 8
`Busy', `Election with wait = false', `Not  
president', `Election without selecting new Severity
candidate', or `No such cause'.             
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: We are Node OWN_ID with      `FIND_NEIGHBOURS'
dynamic ID DYNAMIC_ID, our left neighbour   
is Node ID_1, our right is Node ID_2'       Event Type
                                            
Description                                 `StartUp'
                                            
The node has discovered its neighboring     Priority
nodes in the cluster (node ID_1 and node    
ID_2).  NODE_ID, OWN_ID, and DYNAMIC_ID     8
should always be the same; if they are      
not, this indicates a serious               Severity
misconfiguration of the cluster nodes.      
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: TYPE shutdown initiated'     `NDBStopStarted'
                                            
Description                                 Event Type
                                            
The node has received a shutdown signal.    `StartUp'
The TYPE of shutdown is either `Cluster' or 
`Node'.                                     Priority
                                            
                                            1
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: Node shutdown completed '[`, `NDBStopCompleted'
ACTION'] [`Initiated by signal SIGNAL.']    
                                            Event Type
Description                                 
                                            `StartUp'
The node has been shut down. This report    
may include an ACTION, which if present is  Priority
one of `restarting', `no start', or         
`initial'. The report may also include a    1
reference to an `NDB' Protocol SIGNAL; for  
possible signals, refer to Operations and   Severity
Signals                                     
(http://dev.mysql.com/doc/ndbapi/en/ndb-internals-ndb-protocol-operations-signals.html).`INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: Forced node shutdown         `NDBStopForced'
completed '[`, action']`.' [`Occured        
during startphase START_PHASE.'] [`         Event Type
Initiated by SIGNAL.'] [`Caused by error    
ERROR_CODE:                                 `StartUp'
'ERROR_MESSAGE(ERROR_CLASSIFICATION).       
ERROR_STATUS'.' [`(extra info               Priority
EXTRA_CODE)']]                              
                                            1
Description                                 
                                            Severity
The node has been forcibly shut down. The   
ACTION (one of `restarting', `no start',    `ALERT'
or `initial') subsequently being taken, if  
any, is also reported.  If the shutdown     
occurred while the node was starting, the   
report includes the START_PHASE during      
which the node failed. If this was a        
result of a SIGNAL sent to the node, this   
information is also provided (see           
Operations and Signals                      
(http://dev.mysql.com/doc/ndbapi/en/ndb-internals-ndb-protocol-operations-signals.html),
for more information). If the error         
causing the failure is known, this is also  
included; for more information about `NDB'  
error messages and classifications, see     
`NDB' Errors                                
(http://dev.mysql.com/doc/ndbapi/en/ndb-errors.html).
Log Message                                 Event Name
                                            
`Node NODE_ID: Node shutdown aborted'       `NDBStopAborted'
                                            
Description                                 Event Type
                                            
The node shutdown process was aborted by    `StartUp'
the user.                                   
                                            Priority
                                            
                                            1
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: StartLog: [GCI Keep:         `StartREDOLog'
KEEP_POS LastCompleted: LAST_POS            
NewestRestorable: RESTORE_POS]'             Event Type
                                            
Description                                 `StartUp'
                                            
This reports global checkpoints referenced  Priority
during a node start. The redo log prior to  
KEEP_POS is dropped.  LAST_POS is the last  4
global checkpoint in which data node the    
participated; RESTORE_POS is the global     Severity
checkpoint which is actually used to        
restore all data nodes.                     `INFO'
Log Message                                 Event Name
                                            
STARTUP_MESSAGE [_Listed separately; see    `StartReport'
below._]                                    
                                            Event Type
Description                                 
                                            `StartUp'
There are a number of possible startup      
messages that can be logged under           Priority
different circumstances.                    
                                            4
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: Node restart completed copy  `NR_CopyDict'
of dictionary information'                  
                                            Event Type
Description                                 
                                            `NodeRestart'
Copying of data dictionary information to   
the restarted node has been completed.      Priority
                                            
                                            8
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: Node restart completed copy  `NR_CopyDistr'
of distribution information'                
                                            Event Type
Description                                 
                                            `NodeRestart'
Copying of data distribution information    
to the restarted node has been completed.   Priority
                                            
                                            8
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: Node restart starting to     `NR_CopyFragsStarted'
copy the fragments to Node NODE_ID'         
                                            Event Type
Description                                 
                                            `NodeRestart'
Copy of fragments to starting data node     
NODE_ID has begun                           Priority
                                            
                                            8
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: Table ID = TABLE_ID,         `NR_CopyFragDone'
fragment ID = FRAGMENT_ID have been copied  
to Node NODE_ID'                            Event Type
                                            
Description                                 `NodeRestart'
                                            
Fragment FRAGMENT_ID from table TABLE_ID    Priority
has been copied to data node NODE_ID        
                                            10
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: Node restart completed       `NR_CopyFragsCompleted'
copying the fragments to Node NODE_ID'      
                                            Event Type
Description                                 
                                            `NodeRestart'
Copying of all table fragments to           
restarting data node NODE_ID has been       Priority
completed                                   
                                            8
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
Any of the following:                       `NodeFailCompleted'
                                            
  1. `Node NODE_ID: Node NODE1_ID completed Event Type
     failure of Node NODE2_ID'              
                                            `NodeRestart'
  2. `All nodes completed failure of Node   
     NODE_ID'                               Priority
                                            
  3. `Node failure of NODE_IDBLOCK          8
     completed'                             
Description                                 Severity
                                            
One of the following (each corresponding    `ALERT'
to the same-numbered message listed above): 
                                            
  1. Data node NODE1_ID has detected the    
     failure of data node NODE2_ID          
                                            
  2. All (remaining) data nodes have        
     detected the failure of data node      
     NODE_ID                                
                                            
  3. The failure of data node NODE_ID has   
     been detected in the BLOCK`NDB'        
     kernel block, where block is 1 of      
     `DBTC', `DBDICT', `DBDIH', or          
     `DBLQH'; for more information, see     
     `NDB' Kernel Blocks                    
     (http://dev.mysql.com/doc/ndbapi/en/ndb-internals-kernel-blocks.html)
Log Message                                 Event Name
                                            
`Node MGM_NODE_ID: Node DATA_NODE_ID has    `NODE_FAILREP'
failed.  The Node state at failure was      
STATE_CODE'                                 Event Type
                                            
Description                                 `NodeRestart'
                                            
A data node has failed. Its state at the    Priority
time of failure is described by an          
arbitration state code STATE_CODE: possible 8
state code values can be found in the file  
`include/kernel/signaldata/ArbitSignalData.hpp'.Severity
                                            
                                            `ALERT'
Log Message                                 Event Name
                                            
`President restarts arbitration thread      `ArbitState'
[state=STATE_CODE]' or `Prepare arbitrator  
node NODE_ID [ticket=TICKET_ID]' or         Event Type
`Receive arbitrator node NODE_ID            
[ticket=TICKET_ID]' or `Started arbitrator  `NodeRestart'
node NODE_ID [ticket=TICKET_ID]' or `Lost   
arbitrator node NODE_ID - process failure   Priority
[state=STATE_CODE]' or `Lost arbitrator     
node NODE_ID - process exit                 6
[state=STATE_CODE]' or `Lost arbitrator     
node NODE_ID - ERROR_MESSAGE                Severity
[state=STATE_CODE]'                         
                                            `INFO'
Description                                 
                                            
This is a report on the current state and   
progress of arbitration in the cluster.     
NODE_ID is the node ID of the management    
node or SQL node selected as the            
arbitrator. STATE_CODE is an arbitration    
state code, as found in                     
`include/kernel/signaldata/ArbitSignalData.hpp'.
When an error has occurred, an              
ERROR_MESSAGE, also defined in              
`ArbitSignalData.hpp', is provided.         
TICKET_ID is a unique identifier handed     
out by the arbitrator when it is selected   
to all the nodes that participated in its   
selection; this is used to insure that      
each node requesting arbitration was one    
of the nodes that took part in the          
selection process.                          
Log Message                                 Event Name
                                            
`Arbitration check lost - less than 1/2     `ArbitResult'
nodes left' or `Arbitration check won -     
all node groups and more than 1/2 nodes     Event Type
left' or `Arbitration check won - node      
group majority' or `Arbitration check lost  `NodeRestart'
- missing node group' or `Network           
partitioning - arbitration required' or     Priority
`Arbitration won - positive reply from node 
NODE_ID' or `Arbitration lost - negative    2
reply from node NODE_ID' or `Network        
partitioning - no arbitrator available' or  Severity
`Network partitioning - no arbitrator       
configured' or `Arbitration failure -       `ALERT'
ERROR_MESSAGE [state=STATE_CODE]'           
                                            
Description                                 
                                            
This message reports on the result of       
arbitration.  In the event of arbitration   
failure, an ERROR_MESSAGE and an            
arbitration STATE_CODE are provided;        
definitions for both of these are found in  
`include/kernel/signaldata/ArbitSignalData.hpp'.
Log Message                                 Event Name
                                            
`Node NODE_ID: GCP Take over started'       `GCP_TakeoverStarted'
                                            
Description                                 Event Type
                                            
This node is attempting to assume           `NodeRestart'
responsibility for the next global          
checkpoint (that is, it is becoming the     Priority
master node)                                
                                            7
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: GCP Take over completed'     `GCP_TakeoverCompleted'
                                            
Description                                 Event Type
                                            
This node has become the master, and has    `NodeRestart'
assumed responsibility for the next global  
checkpoint                                  Priority
                                            
                                            7
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: LCP Take over started'       `LCP_TakeoverStarted'
                                            
Description                                 Event Type
                                            
This node is attempting to assume           `NodeRestart'
responsibility for the next set of local    
checkpoints (that is, it is becoming the    Priority
master node)                                
                                            7
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: LCP Take over completed'     `LCP_TakeoverCompleted'
                                            
Description                                 Event Type
                                            
This node has become the master, and has    `NodeRestart'
assumed responsibility for the next set of  
local checkpoints                           Priority
                                            
                                            7
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: Trans. Count =               `TransReportCounters'
TRANSACTIONS, Commit Count = COMMITS, Read  
Count = READS, Simple Read Count =          Event Type
SIMPLE_READS, Write Count = WRITES,         
AttrInfo Count = ATTRINFO_OBJECTS,          `Statistic'
Concurrent Operations =                     
CONCURRENT_OPERATIONS, Abort Count =        Priority
ABORTS, Scans = SCANS, Range scans =        
RANGE_SCANS'                                8
                                            
Description                                 Severity
                                            
This report of transaction activity is      `INFO'
given approximately once every 10 seconds   
Log Message                                 Event Name
                                            
`Node NODE_ID: Operations=OPERATIONS'       `OperationReportCounters'
                                            
Description                                 Event Type
                                            
Number of operations performed by this      `Statistic'
node, provided approximately once every 10  
seconds                                     Priority
                                            
                                            8
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: Table with ID = TABLE_ID     `TableCreated'
created'                                    
                                            Event Type
Description                                 
                                            `Statistic'
A table having the table ID shown has been  
created                                     Priority
                                            
                                            7
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: Mean loop Counter in doJob   `JobStatistic'
last 8192 times = COUNT'                    
                                            Event Type
Description                                 
                                            `Statistic'
                                            
                                            Priority
                                            
                                            9
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Mean send size to Node = NODE_ID last      `SendBytesStatistic'
4096 sends = BYTES bytes'                   
                                            Event Type
Description                                 
                                            `Statistic'
This node is sending an average of BYTES    
bytes per send to node NODE_ID              Priority
                                            
                                            9
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Mean receive size to Node = NODE_ID last   `ReceiveBytesStatistic'
4096 sends = BYTES bytes'                   
                                            Event Type
Description                                 
                                            `Statistic'
This node is receiving an average of BYTES  
of data each time it receives data from     Priority
node NODE_ID                                
                                            9
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: Data usage is                `MemoryUsage'
DATA_MEMORY_PERCENTAGE% (DATA_PAGES_USED    
32K pages of total DATA_PAGES_TOTAL)' /     Event Type
`Node NODE_ID: Index usage is               
INDEX_MEMORY_PERCENTAGE% (INDEX_PAGES_USED  `Statistic'
8K pages of total INDEX_PAGES_TOTAL) '      
                                            Priority
Description                                 
                                            5
This report is generated when a `DUMP       
1000' command is issued in the cluster      Severity
management client; for more information,    
see `DUMP 1000'                             `INFO'
(http://dev.mysql.com/doc/ndbapi/en/ndb-internals-dump-command-1000.html),
in MySQL Cluster Internals                  
(http://dev.mysql.com/doc/ndbapi/en/ndb-internals.html)
Log Message                                 Event Name
                                            
`Node NODE1_ID: Transporter to node         `TransporterError'
NODE2_ID reported error ERROR_CODE:         
ERROR_MESSAGE'                              Event Type
                                            
Description                                 `Error'
                                            
A transporter error occurred while          Priority
communicating with node NODE2_ID; for a     
listing of transporter error codes and      2
messages, see `NDB' Transporter Errors      
(http://dev.mysql.com/doc/ndbapi/en/ndb-transporter-errors.html),Severity
in MySQL Cluster Internals                  
(http://dev.mysql.com/doc/ndbapi/en/ndb-internals.html)`ERROR'
Log Message                                 Event Name
                                            
`Node NODE1_ID: Transporter to node         `TransporterWarning'
NODE2_ID reported error ERROR_CODE:         
ERROR_MESSAGE'                              Event Type
                                            
Description                                 `Error'
                                            
A warning of a potential transporter        Priority
problem while communicating with node       
NODE2_ID; for a listing of transporter      8
error codes and messages, see `NDB'         
Transporter Errors                          Severity
(http://dev.mysql.com/doc/ndbapi/en/ndb-transporter-errors.html),
for more information                        `WARNING'
Log Message                                 Event Name
                                            
`Node NODE1_ID: Node NODE2_ID missed        `MissedHeartbeat'
heartbeat HEARTBEAT_ID'                     
                                            Event Type
Description                                 
                                            `Error'
This node missed a heartbeat from node      
NODE2_ID                                    Priority
                                            
                                            8
                                            
                                            Severity
                                            
                                            `WARNING'
Log Message                                 Event Name
                                            
`Node NODE1_ID: Node NODE2_ID declared      `DeadDueToHeartbeat'
dead due to missed heartbeat'               
                                            Event Type
Description                                 
                                            `Error'
This node has missed at least 3 heartbeats  
from node NODE2_ID, and so has declared     Priority
that node `dead'                            
                                            8
                                            
                                            Severity
                                            
                                            `ALERT'
Log Message                                 Event Name
                                            
`Node NODE1_ID: Node Sent Heartbeat to      `SentHeartbeat'
node = NODE2_ID'                            
                                            Event Type
Description                                 
                                            `Info'
This node has sent a heartbeat to node      
NODE2_ID                                    Priority
                                            
                                            12
                                            
                                            Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: Event buffer status:         `EventBufferStatus'
used=BYTES_USED (PERCENT_USED%)             
alloc=BYTES_ALLOCATED (PERCENT_AVAILABLE%)  Event Type
max=BYTES_AVAILABLE                         
apply_gci=LATEST_RESTORABLE_GCI             `Info'
latest_gci=LATEST_GCI'                      
                                            Priority
Description                                 
                                            7
This report is seen during heavy event      
buffer usage, for example, when many        Severity
updates are being applied in a relatively   
short period of time; the report shows the  `INFO'
number of bytes and the percentage of event 
buffer memory used, the bytes allocated and 
percentage still available, and the latest  
and latest restorable global checkpoints    
Log Message                                 Event Name
                                            
`Node NODE_ID: Entering single user mode',  `SingleUser'
`Node NODE_ID: Entered single user mode     
Node API_NODE_ID has exclusive access',     Event Type
`Node NODE_ID: Entering single user mode'   
                                            `Info'
Description                                 
                                            Priority
These reports are written to the cluster    
log when entering and exiting single user   7
mode; API_NODE_ID is the node ID of the     
API or SQL having exclusive access to the   Severity
cluster (fro mroe information, see *Note    
mysql-cluster-single-user-mode::); the      `INFO'
message `Unknown single user report         
API_NODE_ID' indicates an error has taken   
place and should never be seen in normal    
operation                                   
Log Message                                 Event Name
                                            
`Node NODE_ID: Backup BACKUP_ID started     `BackupStarted'
from node MGM_NODE_ID'                      
                                            Event Type
Description                                 
                                            `Backup'
A backup has been started using the         
management node having MGM_NODE_ID; this    Priority
message is also displayed in the cluster    
management client when the `START BACKUP'   7
command is issued; for more information,    
see *Note                                   Severity
mysql-cluster-backup-using-management-client::
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: Backup BACKUP_ID started     `BackupCompleted'
from node MGM_NODE_ID completed. StartGCP:  
START_GCP StopGCP: STOP_GCP #Records:       Event Type
RECORDS #LogRecords: LOG_RECORDS Data:      
DATA_BYTES bytes Log: LOG_BYTES bytes'      `Backup'
                                            
Description                                 Priority
                                            
The backup having the ID BACKUP_ID has been 7
completed; for more information, see *Note  
mysql-cluster-backup-using-management-client::Severity
                                            
                                            `INFO'
Log Message                                 Event Name
                                            
`Node NODE_ID: Backup request from          `BackupFailedToStart'
MGM_NODE_ID failed to start. Error:         
ERROR_CODE'                                 Event Type
                                            
Description                                 `Backup'
                                            
The backup failed to start; for error       Priority
codes, see MGM`' API Errors                 
(http://dev.mysql.com/doc/ndbapi/en/mgm-errors.html)7
                                            
                                            Severity
                                            
                                            `ALERT'
Log Message                                 Event Name
                                            
`Node NODE_ID: Backup BACKUP_ID started     `BackupAborted'
from MGM_NODE_ID has been aborted. Error:   
ERROR_CODE'                                 Event Type
                                            
Description                                 `Backup'
                                            
The backup was terminated after starting,   Priority
possibly due to user intervention           
                                            7
                                            
                                            Severity
                                            
                                            `ALERT'


File: manual.info,  Node: mysql-cluster-ndb-transporter-errors,  Prev: mysql-cluster-logs-cluster-log,  Up: mysql-cluster-logs-ndb-messages

20.7.4.2 `NDB' Transporter Errors
.................................

This section lists error codes, names, and messages that are written to
the cluster log in the event of transporter errors.

Error   Error Name                                  Error Text
Code                                                
0x00    TE_NO_ERROR                                 `No error'
0x01    TE_ERROR_CLOSING_SOCKET                     `Error found during
                                                    closing of socket'
0x02    TE_ERROR_IN_SELECT_BEFORE_ACCEPT            `Error found before
                                                    accept. The
                                                    transporter will
                                                    retry'
0x03    TE_INVALID_MESSAGE_LENGTH                   `Error found in
                                                    message (invalid
                                                    message length)'
0x04    TE_INVALID_CHECKSUM                         `Error found in
                                                    message (checksum)'
0x05    TE_COULD_NOT_CREATE_SOCKET                  `Error found while
                                                    creating socket(can't
                                                    create socket)'
0x06    TE_COULD_NOT_BIND_SOCKET                    `Error found while
                                                    binding server socket'
0x07    TE_LISTEN_FAILED                            `Error found while
                                                    listening to server
                                                    socket'
0x08    TE_ACCEPT_RETURN_ERROR                      `Error found during
                                                    accept(accept return
                                                    error)'
0x0b    TE_SHM_DISCONNECT                           `The remote node has
                                                    disconnected'
0x0c    TE_SHM_IPC_STAT                             `Unable to check shm
                                                    segment'
0x0d    TE_SHM_UNABLE_TO_CREATE_SEGMENT             `Unable to create shm
                                                    segment'
0x0e    TE_SHM_UNABLE_TO_ATTACH_SEGMENT             `Unable to attach shm
                                                    segment'
0x0f    TE_SHM_UNABLE_TO_REMOVE_SEGMENT             `Unable to remove shm
                                                    segment'
0x10    TE_TOO_SMALL_SIGID                          `Sig ID too small'
0x11    TE_TOO_LARGE_SIGID                          `Sig ID too large'
0x12    TE_WAIT_STACK_FULL                          `Wait stack was full'
0x13    TE_RECEIVE_BUFFER_FULL                      `Receive buffer was
                                                    full'
0x14    TE_SIGNAL_LOST_SEND_BUFFER_FULL             `Send buffer was
                                                    full,and trying to
                                                    force send fails'
0x15    TE_SIGNAL_LOST                              `Send failed for
                                                    unknown reason(signal
                                                    lost)'
0x16    TE_SEND_BUFFER_FULL                         `The send buffer was
                                                    full, but sleeping
                                                    for a while solved'
0x0017  TE_SCI_LINK_ERROR                           `There is no link
                                                    from this node to the
                                                    switch'
0x18    TE_SCI_UNABLE_TO_START_SEQUENCE             `Could not start a
                                                    sequence, because
                                                    system resources are
                                                    exumed or no sequence
                                                    has been created'
0x19    TE_SCI_UNABLE_TO_REMOVE_SEQUENCE            `Could not remove a
                                                    sequence'
0x1a    TE_SCI_UNABLE_TO_CREATE_SEQUENCE            `Could not create a
                                                    sequence, because
                                                    system resources are
                                                    exempted. Must reboot'
0x1b    TE_SCI_UNRECOVERABLE_DATA_TFX_ERROR         `Tried to send data
                                                    on redundant link but
                                                    failed'
0x1c    TE_SCI_CANNOT_INIT_LOCALSEGMENT             `Cannot initialize
                                                    local segment'
0x1d    TE_SCI_CANNOT_MAP_REMOTESEGMENT             `Cannot map remote
                                                    segment'
0x1e    TE_SCI_UNABLE_TO_UNMAP_SEGMENT              `Cannot free the
                                                    resources used by
                                                    this segment (step 1)'
0x1f    TE_SCI_UNABLE_TO_REMOVE_SEGMENT             `Cannot free the
                                                    resources used by
                                                    this segment (step 2)'
0x20    TE_SCI_UNABLE_TO_DISCONNECT_SEGMENT         `Cannot disconnect
                                                    from a remote segment'
0x21    TE_SHM_IPC_PERMANENT                        `Shm ipc Permanent
                                                    error'
0x22    TE_SCI_UNABLE_TO_CLOSE_CHANNEL              `Unable to close the
                                                    sci channel and the
                                                    resources allocated'


File: manual.info,  Node: mysql-cluster-single-user-mode,  Next: mysql-cluster-sql-statements,  Prev: mysql-cluster-logs-ndb-messages,  Up: mysql-cluster-management

20.7.5 Single User Mode
-----------------------

_Single user mode_ allows the database administrator to restrict access
to the database system to a single API node, such as a MySQL server
(SQL node) or an instance of `ndb_restore'. When entering single user
mode, connections to all other API nodes are closed gracefully and all
running transactions are aborted. No new transactions are permitted to
start.

Once the cluster has entered single user mode, only the designated API
node is granted access to the database.

You can use the `ALL STATUS' command to see when the cluster has
entered single user mode.

Example:

     ndb_mgm> ENTER SINGLE USER MODE 5

After this command has executed and the cluster has entered single user
mode, the API node whose node ID is `5' becomes the cluster's only
permitted user.

The node specified in the preceding command must be an API node;
attempting to specify any other type of node will be rejected.

*Note*:

When the preceding command is invoked, all transactions running on the
designated node are aborted, the connection is closed, and the server
must be restarted.

The command `EXIT SINGLE USER MODE' changes the state of the cluster's
data nodes from single user mode to normal mode. API nodes -- such as
MySQL Servers -- waiting for a connection (that is, waiting for the
cluster to become ready and available), are again permitted to connect.
The API node denoted as the single-user node continues to run (if still
connected) during and after the state change.

Example:

     ndb_mgm> EXIT SINGLE USER MODE

There are two recommended ways to handle a node failure when running in
single user mode:

   * Method 1:

       1. Finish all single user mode transactions

       2. Issue the `EXIT SINGLE USER MODE' command

       3. Restart the cluster's data nodes

   * Method 2:

     Restart database nodes prior to entering single user mode.


File: manual.info,  Node: mysql-cluster-sql-statements,  Prev: mysql-cluster-single-user-mode,  Up: mysql-cluster-management

20.7.6 Quick Reference: MySQL Cluster SQL Statements
----------------------------------------------------

This section discusses several SQL statements that can prove useful in
managing and monitoring a MySQL server that is connected to a MySQL
Cluster, and in some cases provide information about the cluster itself.

   * `SHOW ENGINE NDB STATUS', `SHOW ENGINE NDBCLUSTER STATUS'

     The output of this statement contains information about the
     server's connection to the cluster, creation and usage of MySQL
     Cluster objects, and binary logging for MySQL Cluster replication.

     See *Note show-engine::, for a usage example and more detailed
     information.

   * `SHOW ENGINES'

     This statement can be used to determine whether or not clustering
     support is enabled in the MySQL server, and if so, whether it is
     active.

     See *Note show-engines::, for more detailed information.

     *Note*:

     In MySQL 5.1, this statement no longer supports a `LIKE' clause.
     However, you can use `LIKE' to filter queries against the
     `INFORMATION_SCHEMA.ENGINES', as discussed in the next item.

   * `SELECT * FROM INFORMATION_SCHEMA.ENGINES [WHERE ENGINE LIKE
     'NDB%']'

     This is the equivalent of `SHOW ENGINES', but uses the `ENGINES'
     table of the `INFORMATION_SCHEMA' database (available beginning
     with MySQL 5.1.5). Unlike the case with the `SHOW ENGINES'
     statement, it is possible to filter the results using a `LIKE'
     clause, and to select specific columns to obtain information that
     may be of use in scripts. For example, the following query shows
     whether the server was built with `NDB' support and, if so,
     whether it is enabled:

          mysql> SELECT SUPPORT FROM INFORMATION_SCHEMA.ENGINES
              ->   WHERE ENGINE LIKE 'NDB%';
          +---------+
          | support |
          +---------+
          | ENABLED |
          +---------+

     See *Note engines-table::, for more information.

   * `SHOW VARIABLES LIKE 'NDB%''

     This statement provides a list of most server system variables
     relating to the `NDB' storage engine, and their values, as shown
     here:

          mysql> SHOW VARIABLES LIKE 'NDB%';
          +-------------------------------------+-------+
          | Variable_name                       | Value |
          +-------------------------------------+-------+
          | ndb_autoincrement_prefetch_sz       | 32    |
          | ndb_cache_check_time                | 0     |
          | ndb_extra_logging                   | 0     |
          | ndb_force_send                      | ON    |
          | ndb_index_stat_cache_entries        | 32    |
          | ndb_index_stat_enable               | OFF   |
          | ndb_index_stat_update_freq          | 20    |
          | ndb_report_thresh_binlog_epoch_slip | 3     |
          | ndb_report_thresh_binlog_mem_usage  | 10    |
          | ndb_use_copying_alter_table         | OFF   |
          | ndb_use_exact_count                 | ON    |
          | ndb_use_transactions                | ON    |
          +-------------------------------------+-------+

     See *Note server-system-variables::, for more information.

   * `SELECT * FROM INFORMATION_SCHEMA.GLOBAL_VARIABLES WHERE
     VARIABLE_NAME LIKE 'NDB%';'

     This statement is the equivalent of the `SHOW' described in the
     previous item, and provides almost identical output, as shown here:

          mysql> SELECT * FROM INFORMATION_SCHEMA.GLOBAL_VARIABLES
              ->   WHERE VARIABLE_NAME LIKE 'NDB%';
          +-------------------------------------+----------------+
          | VARIABLE_NAME                       | VARIABLE_VALUE |
          +-------------------------------------+----------------+
          | NDB_AUTOINCREMENT_PREFETCH_SZ       | 32             |
          | NDB_CACHE_CHECK_TIME                | 0              |
          | NDB_EXTRA_LOGGING                   | 0              |
          | NDB_FORCE_SEND                      | ON             |
          | NDB_INDEX_STAT_CACHE_ENTRIES        | 32             |
          | NDB_INDEX_STAT_ENABLE               | OFF            |
          | NDB_INDEX_STAT_UPDATE_FREQ          | 20             |
          | NDB_REPORT_THRESH_BINLOG_EPOCH_SLIP | 3              |
          | NDB_REPORT_THRESH_BINLOG_MEM_USAGE  | 10             |
          | NDB_USE_COPYING_ALTER_TABLE         | OFF            |
          | NDB_USE_EXACT_COUNT                 | ON             |
          | NDB_USE_TRANSACTIONS                | ON             |
          +-------------------------------------+----------------+

     Unlike the case with the `SHOW' statement, it is possible to
     select individual columns. For example:

          mysql> SELECT VARIABLE_VALUE
              ->   FROM INFORMATION_SCHEMA.GLOBAL_VARIABLES
              ->   WHERE VARIABLE_NAME = 'ndb_force_send';
          +----------------+
          | VARIABLE_VALUE |
          +----------------+
          | ON             |
          +----------------+

     See *Note variables-table::, and *Note server-system-variables::,
     for more information.

   * `SHOW STATUS LIKE 'NDB%''

     This statement shows at a glance whether or not the MySQL server
     is acting as a cluster SQL node, and if so, it provides the MySQL
     server's cluster node ID, the hostname and port for the cluster
     management server to which it is connected, and the number of data
     nodes in the cluster, as shown here:

          mysql> SHOW STATUS LIKE 'NDB%';
          +--------------------------+---------------+
          | Variable_name            | Value         |
          +--------------------------+---------------+
          | Ndb_cluster_node_id      | 10            |
          | Ndb_config_from_host     | 192.168.0.103 |
          | Ndb_config_from_port     | 1186          |
          | Ndb_number_of_data_nodes | 4             |
          +--------------------------+---------------+

     If the MySQL server was built with clustering support, but it is
     not connected to a cluster, all rows in the output of this
     statement contain a zero or an empty string:

          mysql> SHOW STATUS LIKE 'NDB%';
          +--------------------------+-------+
          | Variable_name            | Value |
          +--------------------------+-------+
          | Ndb_cluster_node_id      | 0     |
          | Ndb_config_from_host     |       |
          | Ndb_config_from_port     | 0     |
          | Ndb_number_of_data_nodes | 0     |
          +--------------------------+-------+

     See also *Note show-status::.

   * `SELECT * FROM INFORMATION_SCHEMA.GLOBAL_STATUS WHERE
     VARIABLE_NAME LIKE 'NDB%';'

     Beginning with MySQL 5.1.12, this statement provides similar
     output to the `SHOW' statement discussed in the previous item.
     However, unlike the case with `SHOW STATUS', it is possible using
     the `SELECT' to extract values in SQL for use in scripts for
     monitoring and automation purposes.

     See *Note status-table::, for more information.


File: manual.info,  Node: mysql-cluster-security,  Next: mysql-cluster-backup,  Prev: mysql-cluster-management,  Up: mysql-cluster

20.8 MySQL Cluster Security Issues
==================================

* Menu:

* mysql-cluster-security-networking-issues::  MySQL Cluster Security and Networking Issues
* mysql-cluster-security-mysql-privileges::  MySQL Cluster and MySQL Privileges
* mysql-cluster-security-mysql-security-procedures::  MySQL Cluster and MySQL Security Procedures

This section discusses security considerations to take into account
when setting up and running MySQL Cluster.

Topics to be covered in this chapter include the following:

   * MySQL Cluster and network security issues

   * Configuration issues relating to running MySQL Cluster securely

   * MySQL Cluster and the MySQL privilege system

   * MySQL standard security procedures as applicable to MySQL Cluster


File: manual.info,  Node: mysql-cluster-security-networking-issues,  Next: mysql-cluster-security-mysql-privileges,  Prev: mysql-cluster-security,  Up: mysql-cluster-security

20.8.1 MySQL Cluster Security and Networking Issues
---------------------------------------------------

In this section, we discuss basic network security issues as they
relate to MySQL Cluster. It is extremely important to remember that
MySQL Cluster `out of the box' is not secure; you or your network
administrator must take the proper steps to insure that your cluster
cannot be compromised over the network.

Cluster communication protocols are inherently insecure, and no
encryption or similar security measures are used in communications
between nodes in the cluster. Because network speed and latency have a
direct impact on the cluster's efficiency, it is also not advisable to
employ SSL or other encryption to network connections between nodes, as
such schemes will effectively slow communications.

It is also true that no authentication is used for controlling API node
access to a MySQL Cluster. As with encryption, the overhead of imposing
authentication requirements would have an adverse impact on Cluster
performance.

In addition, there is no checking of the source IP address for either
of the following when accessing the cluster:

   * SQL or API nodes using `free slots' created by empty `[mysqld]' or
     `[api]' sections in the `config.ini' file

     This means that, if there are any empty `[mysqld]' or `[api]'
     sections in the `config.ini' file, then any API nodes (including
     SQL nodes) that know the management server's hostname (or IP
     address) and port can connect to the cluster and access its data
     without restriction. (See *Note
     mysql-cluster-security-mysql-privileges::, for more information
     about this and related issues.)

     *Note*:

     You can exercise some control over SQL and API node access to the
     cluster by specifying a `HostName' parameter for all `[mysqld]' and
     `[api]' sections in the `config.ini' file. However, this also
     means that, should you wish to connect an API node to the cluster
     from a previously unused host, you need to add an `[api]' section
     containing its hostname to the `config.ini' file.

     More information is available elsewhere in this chapter about the
     `HostName' parameter. Also see *Note mysql-cluster-quick::, for
     configuration examples using `HostName' with API nodes.

   * Any `ndb_mgm' client

     This means that any cluster management client that is given the
     management server's hostname (or IP address) and port (if not the
     standard port) can connect to the cluster and execute any
     management client command. This includes commands such as `ALL
     STOP' and `SHUTDOWN'.

For these reasons, it is necessary to protect the cluster on the
network level. The safest network configuration for Cluster is one
which isolates connections between Cluster nodes from any other network
communications. This can be accomplished by any of the following
methods:

  1. Keeping Cluster nodes on a network that is physically separate
     from any public networks. This option is the most dependable;
     however, it is the most expensive to implement.

     We show an example of a MySQL Cluster setup using such a
     physically segregated network here:

     MySQL Cluster on a private network protected with a hardware
     firewall

     This setup has two networks, one private (solid box) for the
     Cluster management servers and data nodes, and one public (dotted
     box) where the SQL nodes reside. (We show the management and data
     nodes connected using a gigabit switch since this provides the
     best performance.) Both networks are protected from the outside by
     a hardware firewall, sometimes also known as a _network-based
     firewall_.

     This network setup is safest because no packets can reach the
     cluster's management or data nodes from outside the network -- and
     none of the cluster's internal communications can reach the
     outside -- without going through the SQL nodes, as long as the SQL
     nodes do not allow any packets to be forwarded. This means, of
     course, that all SQL nodes must be secured against hacking
     attempts.

     *Important*:

     With regard to potential security vulnerabilities, an SQL node is
     no different from any other MySQL server. See *Note
     security-against-attack::, for a description of techniques you can
     use to secure MySQL servers.

  2. Using one or more software firewalls (also known as _host-based
     firewalls_) to control which packets pass through to the cluster
     from portions of the network that do not require access to it. In
     this type of setup, a software firewall must be installed on every
     host in the cluster which might otherwise be accessible from
     outside the local network.

     The host-based option is the least expensive to implement, but
     relies purely on software to provide protection and so is the most
     difficult to keep secure.

     This type of network setup for MySQL Cluster is illustrated here:

     MySQL Cluster deployed on a network using software firewalls to
     create public and private zones

     Using this type of network setup means that there are two zones of
     MySQL Cluster hosts. Each cluster host must be able to communicate
     with all of the other machines in the cluster, but only those
     hosting SQL nodes (dotted box) can be permitted to have any
     contact with the outside, while those in the zone containing the
     data nodes and management nodes (solid box) must be isolated from
     any machines that are not part of the cluster. Applications using
     the cluster and user of those applications must _not_ be permitted
     to have direct access to the management and data node hosts.

     To accomplish this, you must set up software firewalls that limit
     the traffic to the type or types shown in the following table,
     according to the type of node that is running on each cluster host
     computer:

     Type of Node to   Traffic to Allow
     be Accessed       
     SQL or API node      * It originates from the IP address of a
                            management or data node (using any TCP or
                            UDP port).
                       
                          * It originates from within the network in
                            which the cluster resides and is on the port
                            that your application is using.
     Data node or         * It originates from the IP address of a
     Management node        management or data node (using any TCP or
                            UDP port).
                       
                          * It originates from the IP address of an SQL
                            or API node.
     Any traffic other than that shown in the table for a given node
     type should be denied.

     The specifics of configuring a firewall vary from firewall
     application to firewall application, and are beyond the scope of
     this Manual. `iptables' is a very common and reliable firewall
     application, which is often used with `APF' as a front end to make
     configuration easier. You can (and should) consult the
     documentation for the software firewall that you employ, should
     you choose to implement a MySQL Cluster network setup of this
     type, or of a `mixed' type as discussed under the next item.

  3. It is also possible to employ a combination of the first two
     methods, using both hardware and software to secure the cluster --
     that is, using both network-based and host-based firewalls. This
     is between the first two schemes in terms of both security level
     and cost. This type of network setup keeps the cluster behind the
     hardware firewall, but allows incoming packets to travel beyond the
     router connecting all cluster hosts in order to reach the SQL
     nodes.

     One possible network deployment of a MySQL Cluster using hardware
     and software firewalls in combination is shown here:

     Network setup for MySQL Cluster using a combination of hardware
     and software firewalls to provide protection

     In this case, you can set the rules in the hardware firewall to
     deny any external traffic except to SQL nodes and API nodes, and
     then allow traffic to them only on the ports required by your
     application.

Whatever network configuration you use, remember that your objective
from the viewpoint of keeping the cluster secure remains the same -- to
prevent any unessential traffic from reaching the cluster while
ensuring the most efficient communication between the nodes in the
cluster.

Because MySQL Cluster requires large numbers of ports to be open for
communications between nodes, the recommended option is to use a
segregated network. This represents the simplest way to prevent
unwanted traffic from reaching the cluster.

*Note*:

If you wish to administer a MySQL Cluster remotely (that is, from
outside the local network), the recommended way to do this is to use
`ssh' or another secure login shell to access an SQL node host. From
this host, you can then run the management client to access the
management server safely, from within the Cluster's own local network.

Even though it is possible to do so in theory, it is _not_ recommended
to use `ndb_mgm' to manage a Cluster directly from outside the local
network on which the Cluster is running. Since neither authentication
nor encryption takes place between the management client and the
management server, this represents an extremely insecure means of
managing the cluster, and is almost certain to be compromised sooner or
later.


File: manual.info,  Node: mysql-cluster-security-mysql-privileges,  Next: mysql-cluster-security-mysql-security-procedures,  Prev: mysql-cluster-security-networking-issues,  Up: mysql-cluster-security

20.8.2 MySQL Cluster and MySQL Privileges
-----------------------------------------

In this section, we discuss how the MySQL privilege system works in
relation to MySQL Cluster and the implications of this for keeping a
MySQL Cluster secure.

Standard MySQL privileges apply to MySQL Cluster tables. This includes
all MySQL privilege types (`SELECT' privilege, `UPDATE' privilege,
`DELETE' privilege, and so on) granted on the database, table, and
column level. As with any other MySQL Server, user and privilege
information is stored in the `mysql' system database. The SQL
statements used to grant and revoke privileges on `NDB' tables,
databases containing such tables, and columns within such tables are
identical in all respects with the `GRANT' and `REVOKE' statements used
in connection with database objects involving any (other) MySQL storage
engine. The same thing is true with respect to the `CREATE USER' and
`DROP USER' statements.

It is important to keep in mind that the MySQL grant tables use the
`MyISAM' storage engine. Because of this, those tables are not
duplicated or shared among MySQL servers acting as SQL nodes in a MySQL
Cluster. By way of example, suppose that two SQL nodes *A* and *B* are
connected to the same MySQL Cluster, which has an `NDB' table named
`mytable' in a database named `mydb', and that you execute an SQL
statement on server *A* that creates a new user `jon@localhost' and
grants this user the `SELECT' privilege on that table:

     mysql> GRANT SELECT ON mydb.mytable
         ->   TO jon@localhost IDENTIFIED BY 'mypass';

This user is _not_ created on server *B*. In order for this to take
place, the statement must also be run on server *B*. Similarly,
statements run on server *A* and affecting the privileges of existing
users on server *A* do not affect users on server *B* unless those
statements are actually run on server *B* as well.

In other words, _changes in users and their privileges do not
automatically propagate between SQL nodes_.  Synchronization of
privileges between SQL nodes must be done either manually or by
scripting an application that periodically synchronizes the privilege
tables on all SQL nodes in the cluster.

Conversely, because there is no way in MySQL to deny privileges
(privileges can either be revoked or not granted in the first place,
but not denied as such), there is no special protection for `NDB'
tables on one SQL node from users that have privileges on another SQL
node. The most far-reaching example of this is the MySQL `root'
account, which can perform any action on any database object. In
combination with empty `[mysqld]' or `[api]' sections of the
`config.ini' file, this account can be especially dangerous. To
understand why, consider the following scenario:

   * The `config.ini' file contains at least one empty `[mysqld]' or
     `[api]' section. This means that the Cluster management server
     performs no checking of the host from which a MySQL Server (or
     other API node) accesses the MySQL Cluster.

   * There is no firewall, or the firewall fails to protect against
     access to the Cluster from hosts external to the network.

   * The hostname or IP address of the Cluster's management server is
     known or can be determined from outside the network.

If these conditions are true, then anyone, anywhere can start a MySQL
Server with `--ndbcluster --ndb-connectstring=MANAGEMENT_HOST' and
access the Cluster. Using the MySQL `root' account, this person can
then perform the following actions:

   * Execute a `SHOW DATABASES' statement to obtain a list of all
     databases that exist in the cluster

   * Execute a `SHOW TABLES FROM SOME_DATABASE' statement to obtain a
     list of all `NDB' tables in a given database

   * Run any legal MySQL statements on any of those tables, such as:

        * `SELECT * FROM SOME_TABLE' to read all the data from any table

        * `DELETE FROM SOME_TABLE' to delete all the data from a table

        * `DESCRIBE SOME_TABLE' or `SHOW CREATE TABLE SOME_TABLE' to
          determine the table schema

        * `UPDATE SOME_TABLE SET COLUMN1 = ANY_VALUE1' to fill a table
          column with `garbage' data; this could actually cause much
          greater damage than simply deleting all the data

          Even more insidious variations might include statements like
          these:

               UPDATE SOME_TABLE SET AN_INT_COLUMN = AN_INT_COLUMN + 1

          or


               UPDATE SOME_TABLE SET A_VARCHAR_COLUMN = REVERSE(A_VARCHAR_COLUMN)

          Such malicious statements are limited only by the imagination
          of the attacker.

     The only tables that would be safe from this sort of mayhem would
     be those tables that were created using storage engines other than
     `NDB', and so not visible to a `rogue' SQL node.

     *Note*:

     A user who can log in as `root' can also access the
     `INFORMATION_SCHEMA' database and its tables, and so obtain
     information about databases, tables, stored routines, scheduled
     events, and any other database objects for which metadata is
     stored in `INFORMATION_SCHEMA'.

     It is also a very good idea to use different passwords for the
     `root' accounts on different cluster SQL nodes.

In sum, you cannot have a safe MySQL Cluster if it is directly
accessible from outside your local network.

*Important*:

_Never leave the MySQL root account password empty_. This is just as
true when running MySQL as a MySQL Cluster SQL node as it is when
running it as a standalone (non-Cluster) MySQL Server, and should be
done as part of the MySQL installation process before configuring the
MySQL Server as an SQL node in a MySQL Cluster.

You should never convert the system tables in the `mysql' database to
use the `NDB' storage engine. There are a number of reasons why you
should not do this, but the most important reason is this: _Many of the
SQL statements that affect `mysql' tables storing information about user
privileges, stored routines, scheduled events, and other database
objects cease to function if these tables are changed to use any
storage engine other than `MyISAM'_.  This is a consequence of various
MySQL Server internals which are not expected to change in the
foreseeable future.

If you need to synchronize `mysql' system tables between SQL nodes, you
can use standard MySQL replication to do so, or employ a script to copy
table entries between the MySQL servers.

Summary

The two most important points to remember regarding the MySQL privilege
system with regard to MySQL Cluster are:

  1. Users and privileges established on one SQL node do not
     automatically exist or take effect on other SQL nodes in the
     cluster.

     Conversely, removing a user or privilege on one SQL node in the
     cluster does not remove the user or privilege from any other SQL
     nodes.

  2. Once a MySQL user is granted privileges on an `NDB' table from one
     SQL node in a MySQL Cluster, that user can `see' any data in that
     table regardless of the SQL node from which the data originated.


File: manual.info,  Node: mysql-cluster-security-mysql-security-procedures,  Prev: mysql-cluster-security-mysql-privileges,  Up: mysql-cluster-security

20.8.3 MySQL Cluster and MySQL Security Procedures
--------------------------------------------------

In this section, we discuss MySQL standard security procedures as they
apply to running MySQL Cluster.

In general, any standard procedure for running MySQL securely also
applies to running a MySQL Server as part of a MySQL Cluster.  First
and foremost, you should always run a MySQL Server as the `mysql'
system user; this is no different from running MySQL in a standard
(non-Cluster) environment. The `mysql' system account should be
uniquely and clearly defined. Fortunately, this is the default behavior
for a new MySQL installation. You can verify that the `mysqld' process
is running as the system user `mysql' by using the system command such
as the one shown here:

     shell> ps aux | grep mysql
     root     10467  0.0  0.1   3616  1380 pts/3    S    11:53   0:00 \
       /bin/sh ./mysqld_safe --ndbcluster --ndb-connectstring=localhost:1186
     mysql    10512  0.2  2.5  58528 26636 pts/3    Sl   11:53   0:00 \
       /usr/local/mysql/libexec/mysqld --basedir=/usr/local/mysql \
       --datadir=/usr/local/mysql/var --user=mysql --ndbcluster \
       --ndb-connectstring=localhost:1186 --pid-file=/usr/local/mysql/var/mothra.pid \
       --log-error=/usr/local/mysql/var/mothra.err
     jon      10579  0.0  0.0   2736   688 pts/0    S+   11:54   0:00 grep mysql

If the `mysqld' process is running as any other user than `mysql', you
should immediately shut it down and restart it as the `mysql' user. If
this user does not exist on the system, the `mysql' user account should
be created, and this user should be part of the `mysql' user group; in
this case, you should also make sure that the MySQL `DataDir' on this
system is owned by the `mysql' user, and that the SQL node's `my.cnf'
file includes `user=mysql' in the `[mysqld]' section. Alternatively,
you can start the server with `--user=mysql' on the command line, but
it is preferable to use the `my.cnf' option, since you might forget to
use the command-line option and so have `mysqld' running as another
user unintentionally.  The `mysqld_safe' startup script forces MySQL to
run as the `mysql' user.

*Important*:

Never run `mysqld' as the system root user.  Doing so means that
potentially any file on the system can be read by MySQL, and thus --
should MySQL be compromised -- by an attacker.

As mentioned in the previous section (see *Note
mysql-cluster-security-mysql-privileges::), you should always set a
root password for the MySQL Server as soon as you have it running. You
should also delete the anonymous user account that is installed by
default. You can accomplish these tasks via the following statements:

     shell< mysql -u root

     mysql> UPDATE mysql.user
         ->     SET Password=PASSWORD('SECURE_PASSWORD')
         ->     WHERE User='root';

     mysql> DELETE FROM mysql.user
         ->     WHERE User='';

     mysql> FLUSH PRIVILEGES;

Be very careful when executing the `DELETE' statement not to omit the
`WHERE' clause, or you risk deleting _all_ MySQL users. Be sure to run
the `FLUSH PRIVILEGES' statement as soon as you have modified the
`mysql.user' table, so that the changes take immediate effect. Without
`FLUSH PRIVILEGES', the changes do not take effect until the next time
that the server is restarted.

*Note*:

Many of the MySQL Cluster utilities such as `ndb_show_tables',
`ndb_desc', and `ndb_select_all' also work without authentication and
can reveal table names, schemas, and data. By default these are
installed on Unix-style systems with the permissions `wxr-xr-x' (755),
which means they can be executed by any user that can access the
`mysql/bin' directory.

See *Note mysql-cluster-utilities::, for more information about these
utilities.


File: manual.info,  Node: mysql-cluster-backup,  Next: mysql-cluster-utilities,  Prev: mysql-cluster-security,  Up: mysql-cluster

20.9 On-line Backup of MySQL Cluster
====================================

* Menu:

* mysql-cluster-backup-concepts::  Cluster Backup Concepts
* mysql-cluster-backup-using-management-client::  Using The Management Client to Create a Backup
* mysql-cluster-restore::        `ndb_restore' --- Restore a Cluster Backup
* mysql-cluster-backup-configuration::  Configuration for Cluster Backup
* mysql-cluster-backup-troubleshooting::  Backup Troubleshooting

This section describes how to create a backup and how to restore the
database from a backup at a later time.


File: manual.info,  Node: mysql-cluster-backup-concepts,  Next: mysql-cluster-backup-using-management-client,  Prev: mysql-cluster-backup,  Up: mysql-cluster-backup

20.9.1 Cluster Backup Concepts
------------------------------

A backup is a snapshot of the database at a given time. The backup
consists of three main parts:

   * Metadata

     The names and definitions of all database tables

   * Table records

     The data actually stored in the database tables at the time that
     the backup was made

   * Transaction log

     A sequential record telling how and when data was stored in the
     database

Each of these parts is saved on all nodes participating in the backup.
During backup, each node saves these three parts into three files on
disk:

   * `BACKUP-BACKUP_ID.NODE_ID.ctl'

     A control file containing control information and metadata.  Each
     node saves the same table definitions (for all tables in the
     cluster) to its own version of this file.

   * `BACKUP-BACKUP_ID-0.NODE_ID.data'

     A data file containing the table records, which are saved on a
     per-fragment basis. That is, different nodes save different
     fragments during the backup. The file saved by each node starts
     with a header that states the tables to which the records belong.
     Following the list of records there is a footer containing a
     checksum for all records.

   * `BACKUP-BACKUP_ID.NODE_ID.log'

     A log file containing records of committed transactions. Only
     transactions on tables stored in the backup are stored in the log.
     Nodes involved in the backup save different records because
     different nodes host different database fragments.

In the listing above, BACKUP_ID stands for the backup identifier and
NODE_ID is the unique identifier for the node creating the file.


File: manual.info,  Node: mysql-cluster-backup-using-management-client,  Next: mysql-cluster-restore,  Prev: mysql-cluster-backup-concepts,  Up: mysql-cluster-backup

20.9.2 Using The Management Client to Create a Backup
-----------------------------------------------------

Before starting a backup, make sure that the cluster is properly
configured for performing one. (See *Note
mysql-cluster-backup-configuration::.)

Creating a backup using the management client involves the following
steps:

  1. Start the management client (`ndb_mgm'), if it not running already.

  2. Execute the START BACKUP command.  This produces several lines of
     output indicating the progress of the backup, as shown here:

          ndb_mgm> START BACKUP
          Waiting for completed, this may take several minutes
          Node 2: Backup 1 started from node 1
          Node 2: Backup 1 started from node 1 completed
           StartGCP: 177 StopGCP: 180
           #Records: 7362 #LogRecords: 0
           Data: 453648 bytes Log: 0 bytes
          ndb_mgm>

     The first line printed indicates that the management client is
     waiting for the backup to be completed before returning control to
     the client. This behavior is the default for the `START BACKUP'
     command, but can be changed.  To specify when `START BACKUP'
     command should return control to the client, append `NOWAIT',
     `WAIT STARTED', or `WAIT COMPLETED' to the command. The effects
     that each of these has differs as follows:

        * If `NOWAIT' is specified, the management client displays a
          prompt immediately, as seen here:

               ndb_mgm> START BACKUP NOWAIT
               ndb_mgm>

          In this case, the management client can be used even while it
          prints progress information from the backup process.

        * With `WAIT STARTED' the management client waits until the
          backup has started before returning control to the user, as
          shown here:

               ndb_mgm> START BACKUP WAIT STARTED
               Waiting for started, this may take several minutes
               Node 2: Backup 3 started from node 1
               ndb_mgm>

        * WAIT COMPLETED explicitly specifies the default behavior --
          that is, it causes the management client to wait until the
          backup process is complete before returning control to the
          user.

  3. When the backup has started the management client displays this
     message:

          Backup BACKUP_ID started from node NODE_ID

     BACKUP_ID is the unique identifier for this particular backup.
     This identifier is saved in the cluster log, if it has not been
     configured otherwise. NODE_ID is the identifier of the management
     server that is coordinating the backup with the data nodes. At
     this point in the backup process the cluster has received and
     processed the backup request. It does not mean that the backup has
     finished. An example of this statement is shown here:


          Node 2: Backup 1 started from node 1

  4. The management client indicates that the backup has completed with
     a message in the following format:

          Backup BACKUP_ID started from node NODE_ID completed

     As is the case for the notification that the backup has started,
     BACKUP_ID is the unique identifier for this particular backup, and
     NODE_ID is the node ID of the management server that is
     coordinating the backup with the data nodes. This output is
     accompanied by additional information including relevant global
     checkpoints, the number of records backed up, and the size of the
     data, as shown here:


          Node 2: Backup 1 started from node 1 completed
           StartGCP: 177 StopGCP: 180
           #Records: 7362 #LogRecords: 0
           Data: 453648 bytes Log: 0 bytes

Cluster backups are created by default in the `BACKUP' subdirectory of
the `DataDir' on each data node. This can be overridden for one or more
data nodes individually, or for all cluster data nodes in the
`config.ini' file using the `BackupDataDir' configuration parameter as
discussed in Identifying Data Nodes. The backup files created for a
backup with a given BACKUP_ID are stored in a subdirectory named
`BACKUP-BACKUP_ID' in the backup directory.

To abort a backup that is already in progress:

  1. Start the management client.

  2. Execute this command:

          ndb_mgm> ABORT BACKUP BACKUP_ID

     The number BACKUP_ID is the identifier of the backup that was
     included in the response of the management client when the backup
     was started (in the message `Backup BACKUP_ID started from node
     MANAGEMENT_NODE_ID').

  3. The management client will acknowledge the abort request with
     `Abort of backup BACKUP_ID ordered'.

     *Note*:

     At this point, the management client has not yet received a
     response from the cluster data nodes to this request, and the
     backup has not yet actually been aborted.

  4. After the backup has been aborted, the management client will
     report this fact in a manner similar to what is shown here:

          Node 1: Backup 3 started from 5 has been aborted. Error: 1321 - Backup aborted by user request: Permanent error: User defined error
          Node 3: Backup 3 started from 5 has been aborted. Error: 1323 - 1323: Permanent error: Internal error
          Node 2: Backup 3 started from 5 has been aborted. Error: 1323 - 1323: Permanent error: Internal error
          Node 4: Backup 3 started from 5 has been aborted. Error: 1323 - 1323: Permanent error: Internal error

     In this example, we have shown sample output for a cluster with 4
     data nodes, where the sequence number of the backup to be aborted
     is `3', and the management node to which the cluster management
     client is connected has the node ID `5'. The first node to
     complete its part in aborting the backup reports that the reason
     for the abort was due to a request by the user. (The remaining
     nodes report that the backup was aborted due to an unspecified
     internal error.)

     *Note*:

     There is no guarantee that the cluster nodes respond to an `ABORT
     BACKUP' command in any particular order.

     The `Backup BACKUP_ID started from node MANAGEMENT_NODE_ID has been
     aborted' messages mean that the backup has been terminated and
     that all files relating to this backup have been removed from the
     cluster filesystem.

It is also possible to abort a backup in progress from a system shell
using this command:

     shell> ndb_mgm -e "ABORT BACKUP BACKUP_ID"

*Note*:

If there is no backup with ID BACKUP_ID running when an `ABORT BACKUP'
is issued, the management client makes no response, nor is it indicated
in the cluster log that an invalid abort command was sent.


File: manual.info,  Node: mysql-cluster-restore,  Next: mysql-cluster-backup-configuration,  Prev: mysql-cluster-backup-using-management-client,  Up: mysql-cluster-backup

20.9.3 `ndb_restore' -- Restore a Cluster Backup
------------------------------------------------

The cluster restoration program is implemented as a separate
command-line utility `ndb_restore', which can normally be found in the
MySQL `bin' directory. This program reads the files created as a result
of the backup and inserts the stored information into the database.

`ndb_restore' must be executed once for each of the backup files that
were created by the `START BACKUP' command used to create the backup
(see *Note mysql-cluster-backup-using-management-client::).  This is
equal to the number of data nodes in the cluster at the time that the
backup was created.

*Note*:

Before using `ndb_restore', it is recommended that the cluster be
running in single user mode, unless you are restoring multiple data
nodes in parallel.  See *Note mysql-cluster-single-user-mode::, for
more information about single user mode.

Typical options for this utility are shown here:

     ndb_restore [-c CONNECTSTRING] -n NODE_ID [-s] [-m] -b BACKUP_ID -r [backup_path=]/PATH/TO/BACKUP/FILES [-e]

The `-c' option is used to specify a connectstring which tells
`ndb_restore' where to locate the cluster management server. (See *Note
mysql-cluster-connectstring::, for information on connectstrings.) If
this option is not used, then `ndb_restore' attempts to connect to a
management server on `localhost:1186'. This utility acts as a cluster
API node, and so requires a free connection `slot' to connect to the
cluster management server. This means that there must be at least one
`[api]' or `[mysqld]' section that can be used by it in the cluster
`config.ini' file. It is a good idea to keep at least one empty `[api]'
or `[mysqld]' section in `config.ini' that is not being used for a
MySQL server or other application for this reason (see *Note
mysql-cluster-api-definition::).

You can verify that `ndb_restore' is connected to the cluster by using
the `SHOW' command in the `ndb_mgm' management client.  You can also
accomplish this from a system shell, as shown here:

     shell> ndb_mgm -e "SHOW"

`-n' is used to specify the node ID of the data node on which the
backups were taken.

The first time you run the `ndb_restore' restoration program, you also
need to restore the metadata. In other words, you must re-create the
database tables -- this can be done by running it with the `-m' option.
Note that the cluster should have an empty database when starting to
restore a backup. (In other words, you should start `ndbd' with
`--initial' prior to performing the restore. You should also remove
manually any Disk Data files present in the data node's `DataDir'.)

It is possible to restore data without restoring table metadata. Prior
to MySQL 5.1.17, `ndb_restore' did not perform any checks of table
schemas; if a table was altered between the time the backup was taken
and when `ndb_restore' was run, `ndb_restore' would still attempt to
restore the data to the altered table.

Beginning with MySQL 5.1.17, the default behavior is for `ndb_restore'
is to fail with an error if table data do not match the table schema;
this can be overridden using the `--skip-table-check' or `-s' option.
Prior to MySQL 5.1.21, if this option is used, then `ndb_restore'
attempts to fit data into the existing table schema, but the result of
restoring a backup to a table schema that does not match the original
is unspecified.

Beginning with MySQL Cluster NDB 6.3.8, `ndb_restore' supports limited
_attribute promotion_ in much the same way that it is supported by
MySQL replication; that is, data backed up from a column of a given
type can generally be restored to a column using a `larger, similar'
type. For example, data from a `CHAR(20)' column can be restored to a
column declared as `VARCHAR(20)', `VARCHAR(30)', or `CHAR(30)'; data
from a `MEDIUMINT' column can be restored to a column of type `INT' or
`BIGINT'. See *Note replication-features-different-data-types::, for a
table of type conversions currently supported by attribute promotion.

Attribute promotion by `ndb_restore' must be enabled explicitly, as
follows:

  1. Prepare the table to which the backup is to be restored.
     `ndb_restore' cannot be used to re-create the table with a
     different definition from the original; this means that you must
     either create the table manually, or alter the columns which you
     wish to promote using `ALTER TABLE' after restoring the table
     metadata but before restoring the data.

  2. Invoke `ndb_restore' with the `--promote-attributes' option (short
     form `-A') when restoring the table data.  Attribute promotion
     does not occur if this option is not used; instead, the restore
     operation fails with an error.

In addition to `--promote-attributes', a `--preserve-trailing-spaces'
option is also available for use with `ndb_restore' beginning with
MySQL 5.1.23-ndb-6.3.8. This option (short form `-R') causes trailing
spaces to be preserved when promoting a `CHAR' column to `VARCHAR' or a
`BINARY' column to `VARBINARY'. Otherwise, any trailing spaces are
dropped from column values when they are inserted into the new columns.

*Note*:

Although you can promote `CHAR' columns to `VARCHAR' and `BINARY'
columns to `VARBINARY', you cannot promote `VARCHAR' columns to `CHAR'
or `VARBINARY' columns to `BINARY'.

The `-b' option is used to specify the ID or sequence number of the
backup, and is the same number shown by the management client in the
`Backup BACKUP_ID completed' message displayed upon completion of a
backup. (See *Note mysql-cluster-backup-using-management-client::.)

`-e' adds (or restores) epoch information to the cluster replication
status table. This is useful for starting replication on a MySQL
Cluster replication slave.  When this option is used, the row in the
`mysql.ndb_apply_status' having `0' in the `id' column is updated if it
already exists; such a row is inserted if it does not already exist.
(See *Note mysql-cluster-replication-backups::.)

The path to the backup directory is required, and must include the
subdirectory corresponding to the ID backup of the backup to be
restored. For example, if the data node's `DataDir' is
`/var/lib/mysql-cluster', then the backup directory is
`/var/lib/mysql-cluster/BACKUP', and the backup files for the backup
with the ID 3 can be found in `/var/lib/mysql-cluster/BACKUP/BACKUP-3'.
The path may be absolute or relative to the directory in which the
`ndb_restore' executable is located, and may be optionally prefixed
with `backup_path='.

*Important*:

When restoring cluster backups, you must be sure to restore all data
nodes from backups having the same backup ID. Using files from
different backups will at best result in restoring the cluster to an
inconsistent state, and may fail altogether.

*Important*:

It is not possible to restore a backup made from a newer version of
MySQL Cluster using an older version of `ndb_restore'. You can restore
a backup made from a newer version of MySQL to an older cluster, but
you must use a copy of `ndb_restore' from the newer MySQL Cluster
version to do so.

For example, to restore a cluster backup taken from a cluster running
MySQL 5.1.23 to a cluster running MySQL Cluster 5.1.20, you must use a
copy of `ndb_restore' from the 5.1.23 distribution.

It is possible to restore a backup to a database with a different
configuration than it was created from. For example, suppose that a
backup with backup ID `12', created in a cluster with two database
nodes having the node IDs `2' and `3', is to be restored to a cluster
with four nodes. Then `ndb_restore' must be run twice -- once for each
database node in the cluster where the backup was taken. However,
`ndb_restore' cannot always restore backups made from a cluster running
one version of MySQL to a cluster running a different MySQL version. See
*Note mysql-cluster-upgrade-downgrade-compatibility::, for more
information.

*Note*:

For more rapid restoration, the data may be restored in parallel,
provided that there is a sufficient number of cluster connections
available. That is, when restoring to multiple nodes in parallel, you
must have an `[api]' or `[mysqld]' section in the cluster `config.ini'
file available for each concurrent `ndb_restore' process. However, the
data files must always be applied before the logs.

Formerly, when using `ndb_restore' to restore a backup made from a
MySQL 5.0 cluster to a 5.1 cluster, `VARCHAR' columns were not resized
and were recreated using the 5.0 fixed format. Beginning with MySQL
5.1.19, `ndb_restore' recreates such `VARCHAR' columns using MySQL
Cluster 5.1's variable-width format. Also beginning with MySQL 5.1.19,
this behavior can be overridden using the `--no-upgrade' option (short
form: `-u') when running `ndb_restore'.

Most of the options available for this program are shown in the
following table:

*Long Form*        *Short      *Description*                 *Default
                   Form*                                     Value*
`--backup-id'      `-b'        Backup sequence ID            `0'
`--backup_path'    _None_      Path to backup files          `./'
`--character-sets-dir'_None_      Specify the directory where   _None_
                               character set information     
                               can be found                  
`--connect',       `-c' or     Set the connectstring in      `localhost:1186'
`--connectstring', `-C'        `[nodeid=NODE_ID;][HOST=]HOST[:PORT]'
or                             format                        
`--ndb-connectstring'                                          
`--core-file'      _None_      Write a core file in the      `TRUE'
                               event of an error             
`--debug'          `-#'        Output debug log              `d:t:O,`/tmp/ndb_restore.trace''
`--dont_ignore_systab_0'`-f'        Do not ignore system table    `FALSE'
                               during restore --             
                               _EXPERIMENTAL; not for        
                               production use_               
`--help' or        `-?'        Display help message with     [N/A]
`--usage'                      available options and         
                               current values, then exit     
`--ndb-mgmd-host'  _None_      Set the host and port in      _None_
                               `HOST[:PORT]' format for the  
                               management server to connect  
                               to; this is the same as       
                               `--connect',                  
                               `--connectstring', or         
                               `--ndb-connectstring', but    
                               without a way to specify the  
                               `nodeid'                      
`--ndb-nodegroup-map'`-z'        Specifies a nodegroup map --  _None_
                               _Syntax_: list of             
                               (SOURCE_NODEGROUP,            
                               DESTINATION_NODEGROUP)        
`--ndb-nodeid'     _None_      Specify a node ID for the     `0'
                               `ndb_restore' process         
`--ndb-optimized-node-selection'_None_      Optimize selection of nodes   `TRUE'
                               for transactions              
`--ndb-shm'        _None_      Use shared memory             `FALSE'
                               connections when available    
`--no-binlog'      _None_      Do not write anything to      `FALSE' (in
                               `mysqld' binary logs (added   other words,
                               in MySQL Cluster NDB 6.2.16   write to
                               and 6.3.16)                   binary logs
                                                             unless this
                                                             option is
                                                             used)
`--no-restore-disk-objects'`-d'        Do not restore Disk Data      `FALSE' (in
                               objects such as tablespaces   other words,
                               and log file groups           restore Disk
                                                             Data objects
                                                             unless this
                                                             option is
                                                             used)
`--no-upgrade'     `-u'        Do not re-create `VARSIZE'    `FALSE' (in
                               columns from a MySQL 5.0      other words,
                               Cluster backup as             re-create
                               variable-width columns        `VARSIZE'
                               (added in MySQL 5.1.19)       columns from
                                                             a MySQL 5.0
                                                             Cluster
                                                             backup as
                                                             variable-width
                                                             columns
                                                             unless this
                                                             option is
                                                             used)
`--nodeid'         `-n'        Use backup files from node    `0'
                               with the specified ID         
`--parallelism'    `-p'        Set from 1 to 1024 parallel   `128'
                               transactions to be used       
                               during the restoration        
                               process                       
`--print'          _None_      Print metadata, data, and     `FALSE'
                               log to `stdout'               
`--print_data'     _None_      Print data to `stdout'        `FALSE'
`--print_log'      _None_      Print log to `stdout'         `FALSE'
`--print_meta'     _None_      Print metadata to `stdout'    `FALSE'
`--restore_data'   `-r'        Restore data and logs         `FALSE'
`--restore_epoch'  `-e'        Restore epoch data into the   `FALSE'
                               status table; the row in the  
                               `cluster.apply_status'        
                               having the id `0' is          
                               inserted or updated as        
                               appropriate -- this is        
                               convenient when starting up   
                               replication on a MySQL        
                               Cluster replication slave     
`--restore_meta'   `-m'        Restore table metadata        `FALSE'
`--skip-table-check'`-s'        Do not check table schemas    `FALSE'
                               (Added in MySQL 5.1.17)       
`--version'        `-V'        Output version information    [N/A]
                               and exit                      

Beginning with MySQL 5.1.18, several additional options are available
for use with the `--print_data' option in generating data dumps, either
to `stdout', or to a file. These are similar to some of the options
used with `mysqldump', and are shown in the following table:

*Long Form*        *Short      *Description*                 *Default
                   Form*                                     Value*
`--tab'            `-T'        Creates dumpfiles, one per    _None_
                               table, each named             
                               `TBL_NAME.txt'.  Takes as     
                               its argument the path to the  
                               directory where the files     
                               should be saved (required;    
                               use `.' for the current       
                               directory).                   
`--fields-enclosed-by'_None_      String used to enclose all    _None_
                               column values                 
`--fields-optionally-enclosed-by'_None_      String used to enclose        _None_
                               column values containing      
                               character data (such as       
                               `CHAR', `VARCHAR', `BINARY',  
                               `TEXT', or `ENUM')            
`--fields-terminated-by'_None_      String used to separate       `\t' (tab
                               column values                 character)
`--hex'            _None_      Use hex format for binary     [N/A]
                               values                        
`--lines-terminated-by'_None_      String used to terminate      `\n'
                               each line                     (linefeed
                                                             character)
`--append'         _None_      When used with `--tab',       [N/A]
                               causes the data to be         
                               appended to existing files    
                               of the same name              

*Note*:

If a table has no explicit primary key, then the output generated when
using the `--print' includes the table's hidden primary key.

Beginning with MySQL 5.1.18, it is possible to restore selected
databases, or to restore selected tables from a given database using
the syntax shown here:

     ndb_restore OTHER_OPTIONS DB_NAME_1 [DB_NAME_2[, DB_NAME_3][, ...] | TBL_NAME_1[, TBL_NAME_2][, ...]]

In other words, you can specify either of the following to be restored:

   * All tables from one or more databases

   * One or more tables from a single database

*Note*:

`ndb_restore' reports both temporary and permanent errors. In the case
of temporary errors, it may able to recover from them. Beginning with
MySQL 5.1.12, it reports `Restore successful, but encountered temporary
error, please look at configuration' in such cases.


File: manual.info,  Node: mysql-cluster-backup-configuration,  Next: mysql-cluster-backup-troubleshooting,  Prev: mysql-cluster-restore,  Up: mysql-cluster-backup

20.9.4 Configuration for Cluster Backup
---------------------------------------

Five configuration parameters are essential for backup:

   * `BackupDataBufferSize'

     The amount of memory used to buffer data before it is written to
     disk.

   * `BackupLogBufferSize'

     The amount of memory used to buffer log records before these are
     written to disk.

   * `BackupMemory'

     The total memory allocated in a database node for backups.  This
     should be the sum of the memory allocated for the backup data
     buffer and the backup log buffer.

   * `BackupWriteSize'

     The default size of blocks written to disk. This applies for both
     the backup data buffer and the backup log buffer.

   * `BackupMaxWriteSize'

     The maximum size of blocks written to disk. This applies for both
     the backup data buffer and the backup log buffer.

More detailed information about these parameters can be found in Backup
Parameters.


File: manual.info,  Node: mysql-cluster-backup-troubleshooting,  Prev: mysql-cluster-backup-configuration,  Up: mysql-cluster-backup

20.9.5 Backup Troubleshooting
-----------------------------

If an error code is returned when issuing a backup request, the most
likely cause is insufficient memory or disk space. You should check
that there is enough memory allocated for the backup.

*Important*:

If you have set `BackupDataBufferSize' and `BackupLogBufferSize' and
their sum is greater than 4MB, then you must also set `BackupMemory' as
well. See `BackupMemory'.

You should also make sure that there is sufficient space on the hard
drive partition of the backup target.

`NDB' does not support repeatable reads, which can cause problems with
the restoration process. Although the backup process is `hot',
restoring a MySQL Cluster from backup is not a 100% `hot' process. This
is due to the fact that, for the duration of the restore process,
running transactions get non-repeatable reads from the restored data.
This means that the state of the data is inconsistent while the restore
is in progress.

MySQL Enterprise

MySQL Enterprise subscribers will find more information about Cluster
backup in the Knowledge Base article, How Do I Backup my Cluster
Database (https://kb.mysql.com/view.php?id=5803). Access to the MySQL
Knowledge Base collection of articles is one of the advantages of
subscribing to MySQL Enterprise. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: mysql-cluster-utilities,  Next: mysql-cluster-replication,  Prev: mysql-cluster-backup,  Up: mysql-cluster

20.10 Cluster Utility Programs
==============================

* Menu:

* mysql-cluster-utilities-ndb-config::  `ndb_config' --- Extract NDB Configuration Information
* mysql-cluster-utilities-ndb-cpcd::  `ndb_cpcd' --- Automate Testing for NDB Development
* mysql-cluster-utilities-ndb-delete-all::  `ndb_delete_all' --- Delete All Rows from NDB Table
* mysql-cluster-utilities-ndb-desc::  `ndb_desc' --- Describe NDB Tables
* mysql-cluster-utilities-ndb-drop-index::  `ndb_drop_index' --- Drop Index from NDB Table
* mysql-cluster-utilities-ndb-drop-table::  `ndb_drop_table' --- Drop NDB Table
* mysql-cluster-utilities-ndb-error-reporter::  `ndb_error_reporter' --- NDB Error-Reporting Utility
* mysql-cluster-utilities-ndb-print-backup-file::  `ndb_print_backup_file' --- Print NDB Backup File Contents
* mysql-cluster-utilities-ndb-print-schema-file::  `ndb_print_schema_file' --- Print NDB Schema File Contents
* mysql-cluster-utilities-ndb-print-sys-file::  `ndb_print_sys_file' --- Print NDB System File Contents
* mysql-cluster-utilities-ndbd-redo-log-reader::  `ndbd_redo_log_reader' --- Check and Print Content of Cluster Redo Log
* mysql-cluster-utilities-ndb-select-all::  `ndb_select_all' --- Print Rows from NDB Table
* mysql-cluster-utilities-ndb-select-count::  `ndb_select_count' --- Print Row Counts for NDB Tables
* mysql-cluster-utilities-ndb-show-tables::  `ndb_show_tables' --- Display List of NDB Tables
* mysql-cluster-utilities-ndb-size::  `ndb_size.pl' --- NDBCLUSTER Size Requirement Estimator
* mysql-cluster-utilities-ndb-waiter::  `ndb_waiter' --- Wait for Cluster to Reach a Given Status

This section discusses the MySQL Cluster utility programs that can be
found in the `mysql/bin' directory. Each of these -- except for
`ndb_size.pl' and `ndb_error_reporter' -- is a standalone binary that
can be used from a system shell, and that does not need to connect to a
MySQL server (nor even requires that a MySQL server be connected to the
cluster).

These utilities can also serve as examples for writing your own
applications using the `NDB' API. The source code for most of these
programs may be found in the `storage/ndb/tools' directory of the MySQL
5.1 tree (see *Note installing-source::). The `NDB' API is not covered
in this manual; please refer to the `NDB' API Guide
(http://dev.mysql.com/doc/ndbapi/en/index.html) for information about
this API.

All of the `NDB' utilities are listed here with brief descriptions:

   * `ndb_config': Retrieves Cluster configuration option values.

   * `ndb_cpcd': Used in testing and debugging MySQL Cluster.

   * `ndb_delete_all': Deletes all rows from a given table.

   * `ndb_desc': Lists all properties of an `NDB' table.

   * `ndb_drop_index': Drops the specified index from an `NDB' table.

   * `ndb_drop_table': Drops an `NDB' table.

   * `ndb_error_reporter': Can be used to gather information useful for
     diagnosing problems with the cluster.

   * `ndb_mgm': This is the MySQL Cluster management client, which is
     discussed in *Note mysql-cluster-mgm-client-commands::.

   * `ndb_print_backup_file': Prints diagnostic information obtained
     from cluster backup files.

   * `ndb_print_schema_file': Prints diagnostic information obtained
     from cluster schema files.

   * `ndb_print_sys_file': Prints diagnostic information obtained from
     cluster system files.

   * `ndb_restore': This utility is used to restore a cluster from
     backup. See *Note mysql-cluster-restore::, for more information.

   * `ndb_select_all': Prints all rows from an `NDB' table.

   * `ndb_select_count': Gets the number of rows in one or more `NDB'
     tables.

   * `ndb_show_tables': Shows all `NDB' tables anywhere in the cluster.

   * `ndb_size.pl': Examines all the tables in a given non-Cluster
     database and calculates the amount of storage each would require
     if it were converted to use the `NDB' storage engine.

   * `ndb_waiter': Reports on the status of cluster data nodes in a
     manner similar to that of the management client command `ALL
     STATUS'.

   * `ndbd_redo_log_reader': Reads a redo log file, checking it for
     errors, printing it in a human-readable format, or both.

     *Note*:

     An alpha version of this utility was made available in MySQL
     Cluster NDB 6.1.3. Currently, it should be considered experimental.

Most of these utilities need to connect to a Cluster management server
in order to function. The exceptions are `ndb_size.pl' (see below), and
the following utilities which access a cluster data node filesystem and
so need to be run on a data node host:

   * `ndb_print_backup_file'

   * `ndb_print_schema_file'

   * `ndb_print_sys_file'

   * `ndbd_redo_log_reader'

`ndb_size.pl' is a Perl script which is also intended to be used from
the shell; however it is a MySQL application and must be able to
connect to a MySQL server. See *Note
mysql-cluster-utilities-ndb-size::, for additional requirements for
using this script.

`ndb_error_reporter' is also a Perl script. It is used to gather
cluster data node and management node logs together into a tarball to
submit along with a bug report. It can use `ssh' or `scp' to access the
node filesystems remotely.

Additional information about each of these utilities (except for
`ndb_mgm' and `ndb_restore') can be found in the sections that follow.

*Note*:

All of these utilities (except for `ndb_size.pl' and `ndb_config') can
use the options discussed in *Note mysql-cluster-command-options::.
Additional options specific to each utility program are discussed in the
individual program listings.

The order in which these options are used is generally not important.
For example, all of these commands produce exactly the same output:

   * `ndb_desc -c localhost fish -d test'

   * `ndb_desc fish -c localhost -d test'

   * `ndb_desc -d test fish -c localhost'


File: manual.info,  Node: mysql-cluster-utilities-ndb-config,  Next: mysql-cluster-utilities-ndb-cpcd,  Prev: mysql-cluster-utilities,  Up: mysql-cluster-utilities

20.10.1 `ndb_config' -- Extract NDB Configuration Information
-------------------------------------------------------------

This tool extracts configuration information for data nodes, SQL nodes,
and API nodes from a cluster management node (and possibly its
`config.ini' file).

*Usage*:

     ndb_config OPTIONS

The OPTIONS available for this utility differ somewhat from those used
with the other utilities, and so are listed in their entirety in the
next section, followed by some examples.

*Options*:

   * `--usage', `--help', or `-?'

     Causes `ndb_config' to print a list of available options, and then
     exit.

   * `--version', `-V'

     Causes `ndb_config' to print a version information string, and
     then exit.

   * `--ndb-connectstring=CONNECT_STRING'

     Specifies the connectstring to use in connecting to the management
     server. The format for the connectstring is the same as described
     in *Note mysql-cluster-connectstring::, and defaults to
     `localhost:1186'.

     The use of `-c' as a short version for this option is supported
     for `ndb_config' beginning with MySQL 5.1.12.

   * `--config-file=PATH-TO-FILE'

     Gives the path to the management server's configuration file
     (`config.ini'). This may be a relative or absolute path. If the
     management node resides on a different host from the one on which
     `ndb_config' is invoked, then an absolute path must be used.

   * `--query=QUERY-OPTIONS', `-q' QUERY-OPTIONS

     This is a comma-delimited list of _query options_ -- that is, a
     list of one or more node attributes to be returned. These include
     `id' (node ID), type (node type -- that is, `ndbd', `mysqld', or
     `ndb_mgmd'), and any configuration parameters whose values are to
     be obtained.

     For example,

     `--query=id,type,indexmemory,datamemory' would return the node ID,
     node type, `DataMemory', and `IndexMemory' for each node.

     *Note*:

     If a given parameter is not applicable to a certain type of node,
     than an empty string is returned for the corresponding value. See
     the examples later in this section for more information.

   * `--host=HOSTNAME'

     Specifies the hostname of the node for which configuration
     information is to be obtained.

   * `--id=NODE_ID',

     `--nodeid=NODE_ID'

     Used to specify the node ID of the node for which configuration
     information is to be obtained.

   * `--nodes'

     (Tells `ndb_config' to print information from parameters defined
     in `[ndbd]' sections only. Currently, using this option has no
     affect, since these are the only values checked, but it may become
     possible in future to query parameters set in `[tcp]' and other
     sections of cluster configuration files.)

   * `--type=NODE_TYPE'

     Filters results so that only configuration values applying to
     nodes of the specified NODE_TYPE (`ndbd', `mysqld', or `ndb_mgmd')
     are returned.

   * `--fields=DELIMITER', `-f' DELIMITER

     Specifies a DELIMITER string used to separate the fields in the
     result. The default is ``,'' (the comma character).

     *Note*:

     If the DELIMITER contains spaces or escapes (such as `\n' for the
     linefeed character), then it must be quoted.

   * `--rows=SEPARATOR', `-r' SEPARATOR

     Specifies a SEPARATOR string used to separate the rows in the
     result. The default is a space character.

     *Note*:

     If the SEPARATOR contains spaces or escapes (such as `\n' for the
     linefeed character), then it must be quoted.

*Examples*:

  1. To obtain the node ID and type of each node in the cluster:

          shell> ./ndb_config --query=id,type --fields=':' --rows='\n'
          1:ndbd
          2:ndbd
          3:ndbd
          4:ndbd
          5:ndb_mgmd
          6:mysqld
          7:mysqld
          8:mysqld
          9:mysqld

     In this example, we used the `--fields' options to separate the ID
     and type of each node with a colon character (`:'), and the
     `--rows' options to place the values for each node on a new line
     in the output.

  2. To produce a connectstring that can be used by data, SQL, and API
     nodes to connect to the management server:

          shell> ./ndb_config --config-file=usr/local/mysql/cluster-data/config.ini --query=hostname,portnumber --fields=: --rows=, --type=ndb_mgmd
          192.168.0.179:1186

  3. This invocation of `ndb_config' checks only data nodes (using the
     `--type' option), and shows the values for each node's ID and
     hostname, and its `DataMemory', `IndexMemory', and `DataDir'
     parameters:

          shell> ./ndb_config --type=ndbd --query=id,host,datamemory,indexmemory,datadir -f ' : ' -r '\n'
          1 : 192.168.0.193 : 83886080 : 18874368 : /usr/local/mysql/cluster-data
          2 : 192.168.0.112 : 83886080 : 18874368 : /usr/local/mysql/cluster-data
          3 : 192.168.0.176 : 83886080 : 18874368 : /usr/local/mysql/cluster-data
          4 : 192.168.0.119 : 83886080 : 18874368 : /usr/local/mysql/cluster-data

     In this example, we used the short options `-f' and `-r' for
     setting the field delimiter and row separator, respectively.

  4. To exclude results from any host except one in particular, use the
     `--host' option:

          shell> ./ndb_config --host=192.168.0.176 -f : -r '\n' -q id,type
          3:ndbd
          5:ndb_mgmd

     In this example, we also used the short form `-q' to determine the
     attributes to be queried.

     Similarly, you can limit results to a node with a specific ID
     using the `--id' or `--nodeid' option.


File: manual.info,  Node: mysql-cluster-utilities-ndb-cpcd,  Next: mysql-cluster-utilities-ndb-delete-all,  Prev: mysql-cluster-utilities-ndb-config,  Up: mysql-cluster-utilities

20.10.2 `ndb_cpcd' -- Automate Testing for NDB Development
----------------------------------------------------------

This utility is found in the `libexec' directory. It is part of an
internal automated test framework used in testing and bedugging MySQL
Cluster. Because it can control processes on remote systems, it is not
advisable to use `ndb_cpcd' in a production cluster.

The source files for `ndb_cpcd' may be found in the directory
`storage/ndb/src/cw/cpcd', in the MySQL 5.1 source tree.


File: manual.info,  Node: mysql-cluster-utilities-ndb-delete-all,  Next: mysql-cluster-utilities-ndb-desc,  Prev: mysql-cluster-utilities-ndb-cpcd,  Up: mysql-cluster-utilities

20.10.3 `ndb_delete_all' -- Delete All Rows from NDB Table
----------------------------------------------------------

`ndb_delete_all' deletes all rows from the given `NDB' table. In some
cases, this can be much faster than `DELETE' or even `TRUNCATE'.

*Usage*:

     ndb_delete_all -c CONNECT_STRING TBL_NAME -d DB_NAME

This deletes all rows from the table named TBL_NAME in the database
named DB_NAME. It is exactly equivalent to executing `TRUNCATE
DB_NAME.TBL_NAME' in MySQL.

*Additional Options*:

   * `--transactional', `-t'

     Use of this option causes the delete operation to be performed as
     a single transaction.

     *Warning*:

     With very large tables, using this option may cause the number of
     operations available to the cluster to be exceeded.


File: manual.info,  Node: mysql-cluster-utilities-ndb-desc,  Next: mysql-cluster-utilities-ndb-drop-index,  Prev: mysql-cluster-utilities-ndb-delete-all,  Up: mysql-cluster-utilities

20.10.4 `ndb_desc' -- Describe NDB Tables
-----------------------------------------

`ndb_desc' provides a detailed description of one or more `NDB' tables.

*Usage*:

     ndb_desc -c CONNECT_STRING TBL_NAME -d DB_NAME [-p]

*Sample Output*:

MySQL table creation and population statements:

     USE test;

     CREATE TABLE fish (
         id INT(11) NOT NULL AUTO_INCREMENT,
         name VARCHAR(20),

         PRIMARY KEY pk (id),
         UNIQUE KEY uk (name)
     ) ENGINE=NDBCLUSTER;

     INSERT INTO fish VALUES
         ('','guppy'), ('','tuna'), ('','shark'),
         ('','manta ray'), ('','grouper'), ('','puffer');

Output from `ndb_desc':

     shell> ./ndb_desc -c localhost fish -d test -p
     -- fish --
     Version: 16777221
     Fragment type: 5
     K Value: 6
     Min load factor: 78
     Max load factor: 80
     Temporary table: no
     Number of attributes: 2
     Number of primary keys: 1
     Length of frm data: 268
     Row Checksum: 1
     Row GCI: 1
     TableStatus: Retrieved
     -- Attributes --
     id Int PRIMARY KEY DISTRIBUTION KEY AT=FIXED ST=MEMORY
     name Varchar(20;latin1_swedish_ci) NULL AT=SHORT_VAR ST=MEMORY

     -- Indexes --
     PRIMARY KEY(id) - UniqueHashIndex
     uk(name) - OrderedIndex
     PRIMARY(id) - OrderedIndex
     uk$unique(name) - UniqueHashIndex

     -- Per partition info --
     Partition  Row count  Commit count  Frag fixed memory  Frag varsized memory
     2          2          2             65536              327680
     1          2          2             65536              327680
     3          2          2             65536              327680

     NDBT_ProgramExit: 0 - OK

*Additional Options*:

   * `--extra-partition-info', `-p'

     Prints additional information about the table's partitions.

   * Information about multiple tables can be obtained in a single
     invocation of `ndb_desc' by using their names, separated by
     spaces. All of the tables must be in the same database.


File: manual.info,  Node: mysql-cluster-utilities-ndb-drop-index,  Next: mysql-cluster-utilities-ndb-drop-table,  Prev: mysql-cluster-utilities-ndb-desc,  Up: mysql-cluster-utilities

20.10.5 `ndb_drop_index' -- Drop Index from NDB Table
-----------------------------------------------------

`ndb_drop_index' drops the specified index from an `NDB' table. _It is
recommended that you use this utility only as an example for writing
NDB API applications_ -- see the Warning later in this section for
details.

*Usage*:

     ndb_drop_index -c CONNECT_STRING TABLE_NAME INDEX -d DB_NAME

The statement shown above drops the index named INDEX from the TABLE in
the DATABASE.

*Additional Options*: None that are specific to this application.

*Warning*:

_Operations performed on Cluster table indexes using the NDB API are
not visible to MySQL and make the table unusable by a MySQL server_. If
you use this program to drop an index, then try to access the table from
an SQL node, an error results, as shown here:

     shell> ./ndb_drop_index -c localhost dogs ix -d ctest1
     Dropping index dogs/idx...OK

     NDBT_ProgramExit: 0 - OK

     shell> ./mysql -u jon -p ctest1
     Enter password: *******
     Reading table information for completion of table and column names
     You can turn off this feature to get a quicker startup with -A

     Welcome to the MySQL monitor.  Commands end with ; or \g.
     Your MySQL connection id is 7 to server version: 5.1.12-beta-20060817

     Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

     mysql> SHOW TABLES;
     +------------------+
     | Tables_in_ctest1 |
     +------------------+
     | a                |
     | bt1              |
     | bt2              |
     | dogs             |
     | employees        |
     | fish             |
     +------------------+
     6 rows in set (0.00 sec)

     mysql> SELECT * FROM dogs;
     `ERROR 1296 (HY000): Got error 4243 'Index not found' from NDBCLUSTER'

In such a case, your _only_ option for making the table available to
MySQL again is to drop the table and re-create it. You can use either
the SQL statement`DROP TABLE' or the `ndb_drop_table' utility (see
*Note mysql-cluster-utilities-ndb-drop-table::) to drop the table.


File: manual.info,  Node: mysql-cluster-utilities-ndb-drop-table,  Next: mysql-cluster-utilities-ndb-error-reporter,  Prev: mysql-cluster-utilities-ndb-drop-index,  Up: mysql-cluster-utilities

20.10.6 `ndb_drop_table' -- Drop NDB Table
------------------------------------------

`ndb_drop_table' drops the specified `NDB' table. (If you try to use
this on a table created with a storage engine other than NDB, it fails
with the error `723: No such table exists'.) This operation is
extremely fast -- in some cases, it can be an order of magnitude faster
than using `DROP TABLE' on an `NDB' table from MySQL.

*Usage*:

     ndb_drop_table -c CONNECT_STRING TBL_NAME -d DB_NAME

*Additional Options*: None.


File: manual.info,  Node: mysql-cluster-utilities-ndb-error-reporter,  Next: mysql-cluster-utilities-ndb-print-backup-file,  Prev: mysql-cluster-utilities-ndb-drop-table,  Up: mysql-cluster-utilities

20.10.7 `ndb_error_reporter' -- NDB Error-Reporting Utility
-----------------------------------------------------------

`ndb_error_reporter' creates an archive from data node and management
node log files that can be used to help diagnose bugs or other problems
with a cluster.  _It is highly recommended that you make use of this
utility when filing reports of bugs in MySQL Cluster_.

*Usage*:

     ndb_error_reporter PATH/TO/CONFIG-FILE [USERNAME] [--fs]

This utility is intended for use on a management node host, and
requires the path to the management host configuration file
(`config.ini'). Optionally, you can supply the name of a user that is
able to access the cluster's data nodes via SSH, in order to copy the
data node log files.  ndb_error_reporter then includes all of these
files in archive that is created in the same directory in which it is
run. The archive is named `ndb_error_report_YYYYMMDDHHMMSS.tar.bz2',
where YYYYMMDDHHMMSS is a datetime string.

If the `--fs' is used, then the data node filesystems are also copied
to the management host and included in the archive that is produced by
this script. As data node filesystems can be extremely large even after
being compressed, we ask that you please do _not_ send archives created
using this option to MySQL AB unless you are specifically requested to
do so.


File: manual.info,  Node: mysql-cluster-utilities-ndb-print-backup-file,  Next: mysql-cluster-utilities-ndb-print-schema-file,  Prev: mysql-cluster-utilities-ndb-error-reporter,  Up: mysql-cluster-utilities

20.10.8 `ndb_print_backup_file' -- Print NDB Backup File Contents
-----------------------------------------------------------------

`ndb_print_backup_file' obtains diagnostic information from a cluster
backup file.

*Usage*:

     ndb_print_backup_file FILE_NAME

FILE_NAME is the name of a cluster backup file. This can be any of the
files (`.Data', `.ctl', or `.log' file) found in a cluster backup
directory. These files are found in the data node's backup directory
under the subdirectory `BACKUP-#', where # is the sequence number for
the backup. For more information about cluster backup files and their
contents, see *Note mysql-cluster-backup-concepts::.

Like `ndb_print_schema_file' and `ndb_print_sys_file' (and unlike most
of the other `NDB' utilities that are intended to be run on a
management server host or to connect to a management server)
`ndb_print_backup_file' must be run on a cluster data node, since it
accesses the data node filesystem directly. Because it does not make
use of the management server, this utility can be used when the
management server is not running, and even when the cluster has been
completely shut down.

*Additional Options*: None.


File: manual.info,  Node: mysql-cluster-utilities-ndb-print-schema-file,  Next: mysql-cluster-utilities-ndb-print-sys-file,  Prev: mysql-cluster-utilities-ndb-print-backup-file,  Up: mysql-cluster-utilities

20.10.9 `ndb_print_schema_file' -- Print NDB Schema File Contents
-----------------------------------------------------------------

`ndb_print_schema_file' obtains diagnostic information from a cluster
schema file.

*Usage*:

     ndb_print_schema_file FILE_NAME

FILE_NAME is the name of a cluster schema file. For more information
about cluster schema files, see Cluster Data Node `FileSystemDir' Files
(http://dev.mysql.com/doc/ndbapi/en/ndb-internals-ndbd-filesystemdir-files.html).

Like `ndb_print_backup_file' and `ndb_print_sys_file' (and unlike most
of the other `NDB' utilities that are intended to be run on a
management server host or to connect to a management server)
`ndb_schema_backup_file' must be run on a cluster data node, since it
accesses the data node filesystem directly. Because it does not make
use of the management server, this utility can be used when the
management server is not running, and even when the cluster has been
completely shut down.

*Additional Options*: None.


File: manual.info,  Node: mysql-cluster-utilities-ndb-print-sys-file,  Next: mysql-cluster-utilities-ndbd-redo-log-reader,  Prev: mysql-cluster-utilities-ndb-print-schema-file,  Up: mysql-cluster-utilities

20.10.10 `ndb_print_sys_file' -- Print NDB System File Contents
---------------------------------------------------------------

`ndb_print_sys_file' obtains diagnostic information from a cluster
system file.

*Usage*:

     ndb_print_sys_file FILE_NAME

FILE_NAME is the name of a cluster system file (sysfile). Cluster
system files are located in a data node's data directory (`DataDir');
the path under this directory to system files matches the pattern
`ndb_#_fs/D#/DBDIH/P#.sysfile'.  In each case, the # represents a
number (not necessarily the same number). For more information, see
Cluster Data Node `FileSystemDir' Files
(http://dev.mysql.com/doc/ndbapi/en/ndb-internals-ndbd-filesystemdir-files.html).

Like `ndb_print_backup_file' and `ndb_print_schema_file' (and unlike
most of the other `NDB' utilities that are intended to be run on a
management server host or to connect to a management server)
`ndb_print_backup_file' must be run on a cluster data node, since it
accesses the data node filesystem directly. Because it does not make
use of the management server, this utility can be used when the
management server is not running, and even when the cluster has been
completely shut down.

*Additional Options*: None.


File: manual.info,  Node: mysql-cluster-utilities-ndbd-redo-log-reader,  Next: mysql-cluster-utilities-ndb-select-all,  Prev: mysql-cluster-utilities-ndb-print-sys-file,  Up: mysql-cluster-utilities

20.10.11 `ndbd_redo_log_reader' -- Check and Print Content of Cluster Redo Log
------------------------------------------------------------------------------

Reads a redo log file, checking it for errors, printing its contents in
a human-readable format, or both.  `ndbd_redo_log_reader' is intended
for use primarily by MySQL developers and support personnel in
debugging and diagnosing problems.

This utility was made available as part of default builds beginning
with MySQL Cluster NDB 6.1.3. It remains under development, and its
syntax and behavior are subject to change in future releases. For this
reason, it should be considered experimental at this time.

The C++ source files for `ndbd_redo_log_reader' can be found in the
directory `/storage/ndb/src/kernel/blocks/dblqh/redoLogReader'.

*Usage*:

     ndbd_redo_log_reader FILE_NAME [OPTIONS]

FILE_NAME is the name of a cluster REDO log file. REDO log files are
located in the numbered directories under the data node's data directory
(`DataDir'); the path under this directory to the REDO log files
matches the pattern `ndb_#_fs/D#/LCP/#/T#F#.Data'.  In each case, the #
represents a number (not necessarily the same number). For more
information, see Cluster Data Node `FileSystemDir' Files
(http://dev.mysql.com/doc/ndbapi/en/ndb-internals-ndbd-filesystemdir-files.html).

*Additional Options*:

The name of the file to be read may be followed by one or more of the
options listed here:

   * `-noprint': Do not print the contents of the log file.

   * `-nocheck': Do not check the log filre for errors.

Like `ndb_print_backup_file' and `ndb_print_schema_file' (and unlike
most of the `NDB' utilities that are intended to be run on a management
server host or to connect to a management server)
`ndbd_redo_log_reader' must be run on a cluster data node, since it
accesses the data node filesystem directly. Because it does not make
use of the management server, this utility can be used when the
management server is not running, and even when the cluster has been
completely shut down.


File: manual.info,  Node: mysql-cluster-utilities-ndb-select-all,  Next: mysql-cluster-utilities-ndb-select-count,  Prev: mysql-cluster-utilities-ndbd-redo-log-reader,  Up: mysql-cluster-utilities

20.10.12 `ndb_select_all' -- Print Rows from NDB Table
------------------------------------------------------

`ndb_select_all' prints all rows from an `NDB' table to `stdout'.

*Usage*:

     ndb_select_all -c CONNECT_STRING TBL_NAME -d DB_NAME [> FILE_NAME]

*Additional Options*:

   * `--lock=LOCK_TYPE', `-l LOCK_TYPE'

     Employs a lock when reading the table. Possible values for
     LOCK_TYPE are:

        * `0': Read lock

        * `1': Read lock with hold

        * `2': Exclusive read lock

     There is no default value for this option.

   * `--order=INDEX_NAME', `-o INDEX_NAME'

     Orders the output according to the index named INDEX_NAME. Note
     that this is the name of an index, not of a column, and that the
     index must have been explicitly named when created.

   * `--descending', `-z'

     Sorts the output in descending order. This option can be used only
     in conjunction with the `-o' (`--order') option.

   * `--header=FALSE'

     Excludes column headers from the output.

   * `--useHexFormat' `-x'

     Causes all numeric values to be displayed in hexadecimal format.
     This does not affect the output of numerals contained in strings
     or datetime values.

   * `--delimiter=CHARACTER', `-D CHARACTER'

     Causes the CHARACTER to be used as a column delimiter. Only table
     data columns are separated by this delimiter.

     The default delimiter is the tab character.

   * `--disk'

     Adds a disk reference column to the output. The column is
     non-empty only for Disk Data tables having non-indexed columns.

   * `--rowid'

     Adds a `ROWID' column providing information about the fragments in
     which rows are stored.

   * `--gci'

     Adds a column to the output showing the global checkpoint at which
     each row was last updated. See *Note mysql-cluster-glossary::, and
     *Note mysql-cluster-log-events::, for more information about
     checkpoints.

   * `--tupscan', `-t'

     Scan the table in the order of the tuples.

   * `--nodata'

     Causes any table data to be omitted.

*Sample Output*:

Output from a MySQL `SELECT' statement:

     mysql> SELECT * FROM ctest1.fish;
     +----+-----------+
     | id | name      |
     +----+-----------+
     |  3 | shark     |
     |  6 | puffer    |
     |  2 | tuna      |
     |  4 | manta ray |
     |  5 | grouper   |
     |  1 | guppy     |
     +----+-----------+
     6 rows in set (0.04 sec)

Output from the equivalent invocation of `ndb_select_all':

     shell> ./ndb_select_all -c localhost fish -d ctest1
     id      name
     3       [shark]
     6       [puffer]
     2       [tuna]
     4       [manta ray]
     5       [grouper]
     1       [guppy]
     6 rows returned

     NDBT_ProgramExit: 0 - OK

Note that all string values are enclosed by square brackets
(``['...`]'') in the output of `ndb_select_all'. For a further example,
consider the table created and populated as shown here:

     CREATE TABLE dogs (
         id INT(11) NOT NULL AUTO_INCREMENT,
         name VARCHAR(25) NOT NULL,
         breed VARCHAR(50) NOT NULL,
         PRIMARY KEY pk (id),
         KEY ix (name)
     )
     TABLESPACE ts STORAGE DISK
     ENGINE=NDB;

     INSERT INTO dogs VALUES
         ('', 'Lassie', 'collie'),
         ('', 'Scooby-Doo', 'Great Dane'),
         ('', 'Rin-Tin-Tin', 'Alsatian'),
         ('', 'Rosscoe', 'Mutt');

This demonstrates the use of several additional `ndb_select_all'
options:

     shell> ./ndb_select_all -d ctest1 dogs -o ix -z --gci --disk
     GCI     id name          breed        DISK_REF
     834461  2  [Scooby-Doo]  [Great Dane] [ m_file_no: 0 m_page: 98 m_page_idx: 0 ]
     834878  4  [Rosscoe]     [Mutt]       [ m_file_no: 0 m_page: 98 m_page_idx: 16 ]
     834463  3  [Rin-Tin-Tin] [Alsatian]   [ m_file_no: 0 m_page: 34 m_page_idx: 0 ]
     835657  1  [Lassie]      [Collie]     [ m_file_no: 0 m_page: 66 m_page_idx: 0 ]
     4 rows returned

     NDBT_ProgramExit: 0 - OK


File: manual.info,  Node: mysql-cluster-utilities-ndb-select-count,  Next: mysql-cluster-utilities-ndb-show-tables,  Prev: mysql-cluster-utilities-ndb-select-all,  Up: mysql-cluster-utilities

20.10.13 `ndb_select_count' -- Print Row Counts for NDB Tables
--------------------------------------------------------------

`ndb_select_count' prints the number of rows in one or more `NDB'
tables. With a single table, the result is equivalent to that obtained
by using the MySQL statement `SELECT COUNT(*) FROM TBL_NAME'.

*Usage*:

     ndb_select_count [-c CONNECT_STRING] -dDB_NAME TBL_NAME[, TBL_NAME2[, ...]]

*Additional Options*: None that are specific to this application.
However, you can obtain row counts from multiple tables in the same
database by listing the table names separated by spaces when invoking
this command, as shown under *Sample Output*.

*Sample Output*:

     shell> ./ndb_select_count -c localhost -d ctest1 fish dogs
     6 records in table fish
     4 records in table dogs

     NDBT_ProgramExit: 0 - OK


File: manual.info,  Node: mysql-cluster-utilities-ndb-show-tables,  Next: mysql-cluster-utilities-ndb-size,  Prev: mysql-cluster-utilities-ndb-select-count,  Up: mysql-cluster-utilities

20.10.14 `ndb_show_tables' -- Display List of NDB Tables
--------------------------------------------------------

`ndb_show_tables' displays a list of all `NDB' database objects in the
cluster. By default, this includes not only both user-created tables and
`NDB' system tables, but `NDB'-specific indexes, internal triggers, and
Cluster Disk Data objects as well.

*Usage*:

     ndb_show_tables [-c CONNECT_STRING]

*Additional Options*:

   * `--loops', `-l'

     Specifies the number of times the utility should execute.  This is
     1 when this option is not specified, but if you do use the option,
     you must supply an integer argument for it.

   * `--parsable', `-p'

     Using this option causes the output to be in a format suitable for
     use with `LOAD DATA INFILE'.

   * `--type', `-t'

     Can be used to restrict the output to one type of object,
     specified by an integer type code as shown here:

        * *1*: System table

        * *2*: User-created table

        * *3*: Unique hash index

     Any other value causes all `NDB' database objects to be listed
     (the default).

   * `--unqualified', `-u'

     If specified, this causes unqualified object names to be displayed.

*Note*:

Only user-created Cluster tables may be accessed from MySQL; system
tables such as `SYSTAB_0' are not visible to `mysqld'. However, you can
examine the contents of system tables using `NDB' API applications such
as `ndb_select_all' (see *Note
mysql-cluster-utilities-ndb-select-all::).


File: manual.info,  Node: mysql-cluster-utilities-ndb-size,  Next: mysql-cluster-utilities-ndb-waiter,  Prev: mysql-cluster-utilities-ndb-show-tables,  Up: mysql-cluster-utilities

20.10.15 `ndb_size.pl' -- NDBCLUSTER Size Requirement Estimator
---------------------------------------------------------------

This is a Perl script that can be used to estimate the amount of space
that would be required by a MySQL database if it were converted to use
the `NDBCLUSTER' storage engine. Unlike the other utilities discussed
in this section, it does not require access to a MySQL Cluster (in
fact, there is no reason for it to do so). However, it does need to
access the MySQL server on which the database to be tested resides.

*Requirements*:

   * A running MySQL server. The server instance does not have to
     provide support for MySQL Cluster.

   * A working installation of Perl.

   * The `DBI' module, which can be obtained from CPAN if it is not
     already part of your Perl installation. (Many Linux and other
     operating system distributions provide their own packages for this
     library.)

     *Note*:

     Previous to MySQL 5.1.18, `ndb_size.pl' also required the
     `HTML::Template' module and an associated template file
     `share/mysql/ndb_size.tmpl'.  Beginning with MySQL 5.1.18,
     `ndb_size.tmpl' is no longer needed (or included).

   * A MySQL user account having the necessary privileges. If you do
     not wish to use an existing account, then creating one using
     `GRANT USAGE ON DB_NAME.*' -- where DB_NAME is the name of the
     database to be examined -- is sufficient for this purpose.

`ndb_size.pl' can also be found in the MySQL sources in
`storage/ndb/tools'. If this file is not present in your MySQL
installation, you can obtain it from the MySQL Forge project page
(http://forge.mysql.com/projects/project.php?id=88).

*Usage*:

     ndb_size.pl [--database=DB_NAME|ALL] [--hostname=HOST[:PORT]] [--socket=SOCKET] [--user=USER] \
         [--password=PASSWORD] [--help|-h] [--format=(html|text)] [--loadqueries=FILE_NAME] [--savequeries=FILE_NAME]

By default, this utility attempts to analyze all databases on the
server. You can specify a single database using the `--database'
option; the default behavior can be made explicit by using `ALL' for
the name of the database. You can also exclude one or more databases by
using the `--excludedbs' with a comma-separated list of the names of
the databases to be skipped. Similarly, you can cause specific tables
to be skipped by listing their names, separated by commas, following
the optional `--excludetables' option. A hostname (and possibly a port
as well) can be specified using `--hostname'; the default is
`localhost:3306'. If necessary, you can specify a socket; the default is
`/var/lib/mysql.sock'. A MySQL username and password can be specified
the corresponding options shown. It also possible to control the format
of the output using the `--format' option; this can take either of the
values `html' or `text', with `text' being the default. An example of
the text output is shown here:

     shell> ndb_size.pl --database=test --socket=/tmp/mysql.sock
     ndb_size.pl report for database: 'test' (1 tables)
     --------------------------------------------------
     Connected to: DBI:mysql:host=localhost;mysql_socket=/tmp/mysql.sock

     Including information for versions: 4.1, 5.0, 5.1

     test.t1
     -------

     DataMemory for Columns (* means varsized DataMemory):
                   Column Name                 Type  Varsized   Key       4.1        5.0        5.1
               HIDDEN_NDB_PKEY               bigint             PRI         8          8          8
                            c2          varchar(50)         Y              52         52         4*
                            c1              int(11)                         4          4          4
                                                                           --         --         --
     Fixed Size Columns DM/Row                                             64         64         12
        Varsize Columns DM/Row                                              0          0          4

     DataMemory for Indexes:
                    Index Name                 Type        4.1        5.0        5.1
                       PRIMARY                BTREE         16         16         16
                                                            --         --         --
            Total Index DM/Row                              16         16         16

     IndexMemory for Indexes:
                    Index Name        4.1        5.0        5.1
                       PRIMARY         33         16         16
                                       --         --         --
                Indexes IM/Row         33         16         16

     Summary (for THIS table):
                                      4.1        5.0        5.1
         Fixed Overhead DM/Row         12         12         16
                NULL Bytes/Row          4          4          4
                DataMemory/Row         96         96         48  (Includes overhead, bitmap and indexes)

       Varsize Overhead DM/Row          0          0          8
        Varsize NULL Bytes/Row          0          0          4
            Avg Varside DM/Row          0          0         16

                      No. Rows          0          0          0

             Rows/32kb DM Page        340        340        680
     Fixedsize DataMemory (KB)          0          0          0

     Rows/32kb Varsize DM Page          0          0       2040
       Varsize DataMemory (KB)          0          0          0

              Rows/8kb IM Page        248        512        512
              IndexMemory (KB)          0          0          0

     Parameter Minimum Requirements
     ------------------------------
     * indicates greater than default

                     Parameter          Default             4.1              5.0              5.1
               DataMemory (KB)            81920               0                0                0
            NoOfOrderedIndexes              128               1                1                1
                    NoOfTables              128               1                1                1
              IndexMemory (KB)            18432               0                0                0
         NoOfUniqueHashIndexes               64               0                0                0
                NoOfAttributes             1000               3                3                3
                  NoOfTriggers              768               5                5                5

For debugging purposes, the Perl arrays containing the queries run by
this script can be read from the file specified using can be saved to a
file using `--savequeries'; a file containing such arrays to be read in
during script execution can be specified using `--loadqueries'. Neither
of these options has a default value.

To produce output in HTML format, use the `--format' option and
redirect the output to a file, as shown in this example:

     shell> ndb_size.pl --database=test --socket=/tmp/mysql.sock --format=html > ndb_size.html

(Without the redirection, the output is sent to `stdout'.) This figure
shows a portion of the generated `ndb_size.html' output file, as viewed
in a Web browser:

Partial sample output from `ndb_size.pl' as viewed in a Web browser.

The output from this script includes:

   * Minimum values for the `DataMemory', `IndexMemory',
     `MaxNoOfTables', `MaxNoOfAttributes', `MaxNoOfOrderedIndexes',
     `MaxNoOfUniqueHashIndexes', and `MaxNoOfTriggers' configuration
     parameters required to accommodate the tables analyzed.

   * Memory requirements for all of the tables, attributes, ordered
     indexes, and unique hash indexes defined in the database.

   * The `IndexMemory' and `DataMemory' required per table and table
     row.

*Note*:

Prior to MySQL 5.1.23, MySQL Cluster NDB 6.2.5, and MySQL Cluster NDB
6.3.7, `ndb_size.pl' was invoked as shown here:

     perl ndb_size.pl DB_NAME HOSTNAME USERNAME PASSWORD > FILE_NAME.html

For more information about this change, see Bug#28683
(http://bugs.mysql.com/28683) and Bug#28253
(http://bugs.mysql.com/28253).


File: manual.info,  Node: mysql-cluster-utilities-ndb-waiter,  Prev: mysql-cluster-utilities-ndb-size,  Up: mysql-cluster-utilities

20.10.16 `ndb_waiter' -- Wait for Cluster to Reach a Given Status
-----------------------------------------------------------------

`ndb_waiter' repeatedly (each 100 milliseconds) prints out the status
of all cluster data nodes until either the cluster reaches a given
status or the `--timeout' limit is exceeded, then exits. By default, it
waits for the cluster to achieve `STARTED' status, in which all nodes
have started and connected to the cluster. This can be overridden using
the `--no-contact' and `--not-started' options (see Additional Options).

The node states reported by this utility are as follows:

   * `NO_CONTACT': The node cannot be contacted.

   * `UNKNOWN': The node can be contacted, but its status is not yet
     known. Usually, this means that the node has received a `START' or
     `RESTART' command from the management server, but has not yet
     acted on it.

   * `NOT_STARTED': The node has stopped, but remains in contact with
     the cluster. This is seen when restarting the node using the
     management client's `RESTART' command.

   * `STARTING': The node's `ndbd' process has started, but the node
     has not yet joined the cluster.

   * `STARTED': The node is operational, and has joined the cluster.

   * `SHUTTING_DOWN': The node is shutting down.

   * `SINGLE USER MODE': This is shown for all cluster data nodes when
     the cluster is in single user mode.

*Usage*:

     ndb_waiter [-c CONNECT_STRING]

*Additional Options*:

   * `--no-contact', `-n'

     Instead of waiting for the `STARTED' state, `ndb_waiter' continues
     running until the cluster reaches `NO_CONTACT' status before
     exiting.

   * `--not-started'

     Instead of waiting for the `STARTED' state, `ndb_waiter' continues
     running until the cluster reaches `NOT_STARTED' status before
     exiting.

   * `--timeout=SECONDS', `-t SECONDS'

     Time to wait. The program exits if the desired state is not
     achieved within this number of seconds. The default is 120 seconds
     (1200 reporting cycles).

Sample Output

Shown here is the output from `ndb_waiter' when run against a 4-node
cluster in which two nodes have been shut down and then started again
manually. Duplicate reports (indicated by ``...'') are omitted.

     shell> ./ndb_waiter -c localhost

     Connecting to mgmsrv at (localhost)
     State node 1 STARTED
     State node 2 NO_CONTACT
     State node 3 STARTED
     State node 4 NO_CONTACT
     Waiting for cluster enter state STARTED

     ...

     State node 1 STARTED
     State node 2 UNKNOWN
     State node 3 STARTED
     State node 4 NO_CONTACT
     Waiting for cluster enter state STARTED

     ...

     State node 1 STARTED
     State node 2 STARTING
     State node 3 STARTED
     State node 4 NO_CONTACT
     Waiting for cluster enter state STARTED

     ...

     State node 1 STARTED
     State node 2 STARTING
     State node 3 STARTED
     State node 4 UNKNOWN
     Waiting for cluster enter state STARTED

     ...

     State node 1 STARTED
     State node 2 STARTING
     State node 3 STARTED
     State node 4 STARTING
     Waiting for cluster enter state STARTED

     ...

     State node 1 STARTED
     State node 2 STARTED
     State node 3 STARTED
     State node 4 STARTING
     Waiting for cluster enter state STARTED

     ...

     State node 1 STARTED
     State node 2 STARTED
     State node 3 STARTED
     State node 4 STARTED
     Waiting for cluster enter state STARTED

     NDBT_ProgramExit: 0 - OK

*Note*:

If no connectstring is specified, then `ndb_waiter' tries to connect to
a management on `localhost', and reports `Connecting to mgmsrv at
(null)'.


File: manual.info,  Node: mysql-cluster-replication,  Next: mysql-cluster-disk-data,  Prev: mysql-cluster-utilities,  Up: mysql-cluster

20.11 MySQL Cluster Replication
===============================

* Menu:

* mysql-cluster-replication-abbreviations::  Abbreviations and Symbols
* mysql-cluster-replication-general::  Assumptions and General Requirements
* mysql-cluster-replication-issues::  Known Issues in MySQL Cluster Replication
* mysql-cluster-replication-schema::  Cluster Replication Schema and Tables
* mysql-cluster-replication-preparation::  Preparing the Cluster for Replication
* mysql-cluster-replication-starting::  Starting Replication (Single Replication Channel)
* mysql-cluster-replication-two-channels::  Using Two Replication Channels
* mysql-cluster-replication-failover::  Implementing Failover with MySQL Cluster
* mysql-cluster-replication-backups::  MySQL Cluster Backups With Replication
* mysql-cluster-replication-conflict-resolution::  MySQL Cluster Replication Conflict Resolution

Previous to MySQL 5.1.6, _asynchronous replication_, more usually
referred to simply as `replication', was not available when using MySQL
Cluster. MySQL 5.1.6 introduces master-slave replication of this type
for MySQL Cluster databases. This section explains how to set up and
manage a configuration wherein one group of computers operating as a
MySQL Cluster replicates to a second computer or group of computers. We
assume some familiarity on the part of the reader with standard MySQL
replication as discussed elsewhere in this Manual. (See *Note
replication::).

Normal (non-clustered) replication involves a `master' server and a
`slave' server, the master being the source of the operations and data
to be replicated and the slave being the recipient of these. In MySQL
Cluster, replication is conceptually very similar but can be more
complex in practice, as it may be extended to cover a number of
different configurations including replicating between two complete
clusters. Although a MySQL Cluster itself depends on the `NDBCLUSTER'
storage engine for clustering functionality, it is not necessary to use
the Cluster storage engine on the slave. However, for maximum
availability, it is possible to replicate from one MySQL Cluster to
another, and it is this type of configuration that we discuss, as shown
in the following figure:

MySQL Cluster-to-Cluster Replication Layout

In this scenario, the replication process is one in which successive
states of a master cluster are logged and saved to a slave cluster.
This process is accomplished by a special thread known as the NDB
binlog injector thread, which runs on each MySQL server and produces a
binary log (`binlog'). This thread ensures that all changes in the
cluster producing the binary log -- and not just those changes that are
effected via the MySQL Server -- are inserted into the binary log with
the correct serialization order. We refer to the MySQL replication
master and replication slave servers as replication servers or
replication nodes, and the data flow or line of communication between
them as a _replication channel_.


File: manual.info,  Node: mysql-cluster-replication-abbreviations,  Next: mysql-cluster-replication-general,  Prev: mysql-cluster-replication,  Up: mysql-cluster-replication

20.11.1 Abbreviations and Symbols
---------------------------------

Throughout this section, we use the following abbreviations or symbols
for referring to the master and slave clusters, and to processes and
commands run on the clusters or cluster nodes:

*Symbol or         *Description (Refers to...)*
Abbreviation*      
M                  The cluster serving as the (primary) replication
                   master
S                  The cluster acting as the (primary) replication slave
`shellM>'          Shell command to be issued on the master cluster
`mysqlM>'          MySQL client command issued on a single MySQL server
                   running as an SQL node on the master cluster
`mysqlM*>'         MySQL client command to be issued on all SQL nodes
                   participating in the replication master cluster
`shellS>'          Shell command to be issued on the slave cluster
`mysqlS>'          MySQL client command issued on a single MySQL server
                   running as an SQL node on the slave cluster
`mysqlS*>'         MySQL client command to be issued on all SQL nodes
                   participating in the replication slave cluster
C                  Primary replication channel
C'                 Secondary replication channel
M'                 Secondary replication master
S'                 Secondary replication slave


File: manual.info,  Node: mysql-cluster-replication-general,  Next: mysql-cluster-replication-issues,  Prev: mysql-cluster-replication-abbreviations,  Up: mysql-cluster-replication

20.11.2 Assumptions and General Requirements
--------------------------------------------

A replication channel requires two MySQL servers acting as replication
servers (one each for the master and slave). For example, this means
that in the case of a replication setup with two replication channels
(to provide an extra channel for redundancy), there will be a total of
four replication nodes, two per cluster.

Replication of a MySQL Cluster as described in this section and those
following is dependent on row-based replication. This means that the
replication master MySQL server must be started with
`--binlog-format=ROW' or `--binlog-format=MIXED', as described in *Note
mysql-cluster-replication-starting::. For general information about
row-based replication, see *Note replication-formats::.

(It is possible to replicate a MySQL Cluster using statement-based
replication. However, in this case, the following restrictions apply:
All updates to data rows on the cluster acting as the master must be
directed to a single MySQL server; It is not possible to replicate a
cluster using several MySQL replication processes at the same time;
Only changes made at the SQL level are replicated.)

Each MySQL server used for replication in either cluster must be
uniquely identified among all the MySQL replication servers
participating in either cluster (you cannot have replication servers on
both the master and slave clusters sharing the same ID). This can be
done by starting each SQL node using the `--server-id=ID' option, where
ID is a unique integer.  Although it is not strictly necessary, we will
assume for purposes of this discussion that all MySQL installations are
the same version.

In any event, both MySQL servers involved in replication must be
compatible with one another with respect to both the version of the
replication protocol used and the SQL feature sets which they support;
the simplest and easiest way to assure that this is the case is to use
the same MySQL version for all servers involved.  Note that in many
cases it is not possible to replicate to a slave running a version of
MySQL with a lower version number than that of the master -- see *Note
replication-compatibility::, for details.

We assume that the slave server or cluster is dedicated to replication
of the master, and that no other data is being stored on it.


File: manual.info,  Node: mysql-cluster-replication-issues,  Next: mysql-cluster-replication-schema,  Prev: mysql-cluster-replication-general,  Up: mysql-cluster-replication

20.11.3 Known Issues in MySQL Cluster Replication
-------------------------------------------------

The following are known problems or issues when using replication with
MySQL Cluster in MySQL 5.1:

   * Loss of master-slave connection

     Prior to MySQL 5.1.18, a MySQL Cluster replication slave `mysqld'
     had no way of detecting that the connection from the master had
     been interrupted (due to, for instance, the master going down or a
     network failure). For this reason, it was possible for the slave
     to become inconsistent with the master.

     Beginning with MySQL 5.1.18, the master issues a `gap' event when
     connecting to the cluster. When the slave encounters a gap in the
     replication log, it stops with an error message. This message is
     available in the output of `SHOW SLAVE STATUS', and indicates that
     the SQL thread has stopped due to an incident registered in the
     replication stream, and that manual intervention is required. In
     order to restart the slave, it is necessary to issue the following
     commands:

          SET GLOBAL SQL_SLAVE_SKIP_COUNTER = 1;
          START SLAVE;

     The slave then resumes reading the master binlog from the point
     where the gap was recorded.

     *Important*:

     If high availability is a requirement for the slave server or
     cluster, then it is still advisable to set up multiple replication
     lines, to monitor the master `mysqld' on the primary replication
     line, and to fail over to a secondary line if and as necessary.
     For information about implementing this type of setup, see *Note
     mysql-cluster-replication-two-channels::, and *Note
     mysql-cluster-replication-failover::.

     However, if you are replicating from a standalone MySQL server to
     a MySQL Cluster, one channel is usually sufficient.

   * Multi-byte character sets

     There are several known issues with regard to the use of
     multi-byte characters sets with MySQL Cluster Replication.  See
     Bug#27404 (http://bugs.mysql.com/27404) (fixed in MySQL 5.1.21),
     Bug#29562 (http://bugs.mysql.com/29562), Bug#29563
     (http://bugs.mysql.com/29563), and Bug#29564
     (http://bugs.mysql.com/29564) for more information.

   * Circular replication

     Prior to MySQL 5.1.18, circular replication was not supported with
     MySQL Cluster replication, due to the fact that all log events
     created in a particular MySQL Cluster were wrongly tagged with the
     server ID of the MySQL server used as master and not with the
     server ID of the originating server.

     Beginning with MySQL 5.1.18, this limitation is lifted, as
     discussed in the next few paragraphs, in which we consider the
     example of a replication setup involving three MySQL Clusters
     numbered 1, 2, and 3, in which Cluster 1 acts as the replication
     master for Cluster 2, Cluster 2 acts as the master for Cluster 3,
     and Cluster 3 acts as the master for Cluster 1.  Each cluster has
     two SQL nodes, with SQL nodes A and B belonging to Cluster 1, SQL
     nodes C and D belonging to Cluster 2, and SQL nodes E and F
     belonging to Cluster 3.

     Circular replication using these clusters is supported as long as:

        * the SQL nodes on all masters and slaves are the same

        * All SQL nodes acting as replication masters and slaves are
          started using the `--log-slave-updates' option

     This type of circular replication setup is shown in the following
     diagram:

     Cluster circular replication scheme in which all master SQL nodes
     are also slaves.

     In this scenario, SQL node A in Cluster 1 replicates to SQL node C
     in Cluster 2; SQL node C replicates to SQL node E in Cluster 3;
     SQL node E replicates to SQL node A. In other words, the
     replication line (indicated by the red arrows in the diagram)
     directly connects all SQL nodes used as replication masters and
     slaves.

     It should also be possible to set up circular replication in which
     not all master SQL nodes are also slaves, as shown here:

     Cluster circular replication scheme in which all master SQL nodes
     are not also necessarily slaves.

     In this case, different SQL nodes in each cluster are used as
     replication masters and slaves. However, you must _not_ start any
     of the SQL nodes using `--log-slave-updates' (see the description
     of this option for more information). This type of circular
     replication scheme for MySQL Cluster, in which the line of
     replication (again indicated by the red arrows in the diagram) is
     discontinuous, should be possible, but it should be noted that it
     has not yet been thoroughly tested and must therefore still be
     considered experimental.

     *Important*:

     Beginning with MySQL 5.1.24, you should execute the following
     statement before starting circular replication:

          mysql> SET GLOBAL SLAVE_EXEC_MODE = 'IDEMPOTENT';

     This is necessary to suppress duplicate-key and other errors that
     otherwise break circular replication of MySQL Cluster.
     `IDEMPOTENT' mode is also required for multi-master replication
     when using MySQL Cluster. (Bug#31609 (http://bugs.mysql.com/31609))

     See `Slave_exec_mode', for more information.

   * DDL statements

     The use of data definition statements, such as `CREATE TABLE',
     `DROP TABLE', and `ALTER TABLE', are recorded in the binary log
     for only the MySQL server on which they are issued.

   * Cluster replication and primary keys

     In MySQL 5.1.6, only those `NDB' tables having explicit primary
     keys could be replicated. This limitation was lifted in MySQL
     5.1.7. However, in the event of a node failure, errors in
     replication of `NDB' tables without primary keys can still occur,
     due to the possibility of duplicate rows being inserted in such
     cases. For this reason, it is highly recommended that all `NDB'
     tables being replicated have primary keys.

   * Restarting with `--initial'

     Restarting the cluster with the `--initial' option causes the
     sequence of GCI and epoch numbers to start over from `0'. (This is
     generally true of MySQL Cluster and not limited to replication
     scenarios involving Cluster.) The MySQL servers involved in
     replication should in this case be restarted. After this, you
     should use the `RESET MASTER' and `RESET SLAVE' statements to
     clear the invalid `ndb_binlog_index' and `ndb_apply_status'
     tables. respectively.

   * `auto_increment_offset' and `auto_increment_increment' variables

     The use of the `auto_increment_offset' and
     `auto_increment_increment' server system variables is supported
     beginning with MySQL 5.1.20.  Previously, these produced
     unpredictable results when used with `NDB' tables or MySQL Cluster
     replication.

   * Replication from `NDBCLUSTER' to other storage engines

     If you attempt to replicate from a MySQL Cluster to a slave that
     uses a storage engine that does not handle its own binary logging,
     the replication process aborts with the error `Binary logging not
     possible ... Statement cannot be written atomically since more
     than one engine involved and at least one engine is self-logging'
     (Error 1595). It is possible to work around this issue in one of
     the following ways:

        * Turn off binary logging on the slave

          This can be accomplished by setting `SQL_LOG_BIN = 0'.

        * Change the storage engine used for the
          `mysql.ndb_apply_status' table

          Causing this table to use an engine that does not handle its
          own binary logging can also eliminate the conflict. This can
          be done by issuing a statement such as `ALTER TABLE
          mysql.ndb_apply_status ENGINE=MyISAM' on the slave. It is
          safe to do this when using a non-`NDB' storage engine on the
          slave, since you do not then need to worry about keeping
          multiple slave SQL nodes synchronized.

        * Filter out changes to the `mysql.ndb_apply_status' table on
          the slave

          This can be done by starting the slave SQL node with the
          option `--replicate-ignore-table=mysql.ndb_apply_status'.  If
          you need for other tables to be ignored by replication, you
          might wish to use an appropriate
          `--replicate-wild-ignore-table' option instead.

     *Important*:

     You should _not_ disable replication or binary logging of
     `mysql.ndb_apply_status' or change the storage engine used for
     this table when replicating from one MySQL Cluster to another. See
     `Replication and binary log filtering rules with replication
     between MySQL Clusters' elsewhere in this section for details.

   * Replication and binary log filtering rules with replication between
     MySQL Clusters

     If you are using any of the options `--replicate-do-*',
     `--replicate-ignore-*', `--binlog-do-db', or `--binlog-ignore-db'
     to filter databases or tables being replicated, care must be taken
     not to block replication or binary logging of the
     `mysql.ndb_apply_status', which is required for replication
     between MySQL Clusters to operate properly.  In particular, you
     must keep in mind the following:

       1. Using `--replicate-do-db=DB_NAME' (and no other
          `--replicate-do-*' or `--replicate-ignore-*' options) means
          that _only_ tables in database DB_NAME are replicated. In
          this case, you should also use `--replicate-do-db=mysql',
          `--binlog-do-db=mysql', or
          `--replicate-do-table=mysql.ndb_apply_status' to insure that
          `mysql.ndb_apply_status' is populated on slaves.

          Using `--binlog-do-db=DB_NAME' (and no other `--binlog-do-db'
          options) means that changes _only_ to tables in database
          DB_NAME are written to the binary log. In this case, you
          should also use `--replicate-do-db=mysql',
          `--binlog-do-db=mysql', or
          `--replicate-do-table=mysql.ndb_apply_status' to insure that
          `mysql.ndb_apply_status' is populated on slaves.

       2. Using `--replicate-ignore-db=mysql' means that no tables in
          the `mysql' database are replicated. In this case, you should
          also use `--replicate-do-table=mysql.ndb_apply_status' to
          insure that `mysql.ndb_apply_status' is replicated.

          Using `--binlog-ignore-db=mysql' means that no changes to
          tables in the `mysql' database are written to the binary log.
          In this case, you should also use
          `--replicate-do-table=mysql.ndb_apply_status' to insure that
          `mysql.ndb_apply_status' is replicated.

     You should also remember that:

       1. Each replication filtering rule requires its own
          `--replicate-do-*' or `--replicate-ignore-*' option, and that
          multiple rules cannot be expressed in a single replication
          filtering option. For information about these rules, see
          *Note replication-options::.

       2. Each binary log filtering rule requires its own
          `--binlog-do-db' or `--binlog-ignore-db' option, and that
          multiple rules cannot be expressed in a single binary log
          filtering option. For information about these rules, see
          *Note binary-log::.

     *Note*:

     If you are replicating a MySQL Cluster to a slave that uses a
     storage engine other than `NDBCLUSTER', the considerations just
     given previously may not apply. See `Replication from `NDBCLUSTER'
     to other storage engines' elsewhere in this this section for
     details.


File: manual.info,  Node: mysql-cluster-replication-schema,  Next: mysql-cluster-replication-preparation,  Prev: mysql-cluster-replication-issues,  Up: mysql-cluster-replication

20.11.4 Cluster Replication Schema and Tables
---------------------------------------------

Replication in MySQL Cluster makes use of a number of dedicated tables
in the `mysql' database on each MySQL Server instance acting as an SQL
node in both the cluster being replicated and the replication slave
(whether the slave is a single server or a cluster). These tables are
created during the MySQL installation process by the `mysql_install_db'
script, and include a table for storing the binary log's indexing data.
Since the `ndb_binlog_index' table is local to each MySQL server and
does not participate in clustering, it uses the `MyISAM' storage
engine. This means that it must be created separately on each `mysqld'
participating in the master cluster. (However, the binlog itself
contains updates from all MySQL servers in the cluster to be
replicated.) This table is defined as follows:


     CREATE TABLE `ndb_binlog_index` (
         `Position`  BIGINT(20) UNSIGNED NOT NULL,
         `File`      VARCHAR(255) NOT NULL,
         `epoch`     BIGINT(20) UNSIGNED NOT NULL,
         `inserts`   BIGINT(20) UNSIGNED NOT NULL,
         `updates`   BIGINT(20) UNSIGNED NOT NULL,
         `deletes`   BIGINT(20) UNSIGNED NOT NULL,
         `schemaops` BIGNINT(20) UNSIGNED NOT NULL,
         PRIMARY KEY (`epoch`)
     ) ENGINE=MYISAM  DEFAULT CHARSET=latin1;

*Important*:

Prior to MySQL 5.1.14, the `ndb_binlog_index' table was known as
`binlog_index', and was kept in a separate `cluster' database, which in
MySQL 5.1.7 and earlier was known as the `cluster_replication'
database. Similarly, the `ndb_apply_status' and `ndb_schema' tables
were known as `apply_status' and `schema', and were also found in the
`cluster' (earlier `cluster_replication') database. However, beginning
with MySQL 5.1.14, all MySQL Cluster replication tables reside in the
`mysql' system database.

Information about how this change affects upgrades from MySQL Cluster
5.1.13 and earlier to 5.1.14 and later versions can be found in *Note
news-5-1-14::.

Beginning with MySQL Cluster NDB 6.3.2, this table has been changed to
facilitate 3-way replication recovery. Two columns `orig_server_id' and
`orig_epoch' have been added to this table; when `mysqld' is started
with the `--ndb-log-orig' option, these columns store, respectively,
the ID of the server on which the event originated and the epoch in
which the event took place on the originating server. In addition, the
table's primary key now includes these two columns. The modified table
definition is shown here:

     CREATE TABLE `ndb_binlog_index` (
         `Position` BIGINT(20) UNSIGNED NOT NULL,
         `File` VARCHAR(255) NOT NULL,
         `epoch` BIGINT(20) UNSIGNED NOT NULL,
         `inserts` INT(10) UNSIGNED NOT NULL,
         `updates` INT(10) UNSIGNED NOT NULL,
         `deletes` INT(10) UNSIGNED NOT NULL,
         `schemaops` INT(10) UNSIGNED NOT NULL,
         `orig_server_id` INT(10) UNSIGNED NOT NULL,
         `orig_epoch` BIGINT(20) UNSIGNED NOT NULL,
         `gci` INT(10) UNSIGNED NOT NULL
         PRIMARY KEY (`epoch`,`orig_server_id`,`orig_epoch`)
     ) ENGINE=MyISAM DEFAULT CHARSET=latin1;

The `gci' column was added in MySQL Cluster NDB 6.2.6 and MySQL Cluster
NDB 6.3.2.

The following figure shows the relationship of the MySQL Cluster
replication master server, its binlog injector thread, and the
`mysql.ndb_binlog_index' table.

The replication master cluster, the binlog-injector thread, and the
`ndb_binlog_index' table

An additional table, named `ndb_apply_status', is used to keep a record
of the operations that have been replicated from the master to the
slave. Unlike the case with `ndb_binlog_index', the data in this table
is not specific to any one SQL node in the (slave) cluster, and so
`ndb_apply_status' can use the `NDB Cluster' storage engine, as shown
here:

     CREATE TABLE `ndb_apply_status` (
         `server_id`   INT(10) UNSIGNED NOT NULL,
         `epoch`       BIGINT(20) UNSIGNED NOT NULL,
         `log_name`    VARCHAR(255) CHARACTER SET latin1 COLLATE latin1_bin NOT NULL,
         `start_pos`   BIGINT(20) UNSIGNED NOT NULL,
         `end_pos`     BIGINT(20) UNSIGNED NOT NULL,
         PRIMARY KEY (`server_id`) USING HASH
     ) ENGINE=NDBCLUSTER   DEFAULT CHARSET=latin1;

This table is populated only on slaves; on the master, no `DataMemory'
is allocated to it. However, the table is populated _from_ the master.
For this reason, this table must be replicated and any replication
filtering or binary log filtering rules that prevent this prevent
replication between clusters from operating properly. For more
information about potential problems arising from such filtering rules,
see *Note mysql-cluster-replication-issues::.

The `log_name', `start_pos', and `end_pos' columns were added in MySQL
5.1.18.

*Important*:

If you are using MySQL Cluster replication, see *Note
mysql-cluster-upgrade-downgrade-compatibility:: before upgrading to
MySQL 5.1.18 or later from an earlier version.

The `ndb_binlog_index' and `ndb_apply_status' tables are created in the
`mysql' database because they should not be replicated. No user
intervention is normally required to create or maintain either of them.
Both the `ndb_binlog_index' and the `ndb_apply_status' tables are
maintained by the `NDB' injector thread. This keeps the master `mysqld'
process updated to changes performed by the `NDB' storage engine. The
`NDB' _binlog injector thread_ receives events directly from the `NDB'
storage engine. The `NDB' injector is responsible for capturing all the
data events within the cluster, and ensures that all events which
change, insert, or delete data are recorded in the `ndb_binlog_index'
table. The slave I/O thread transfers the events from the master's
binary log to the slave's relay log.

However, it is advisable to check for the existence and integrity of
these tables as an initial step in preparing a MySQL Cluster for
replication. It is possible to view event data recorded in the binary
log by querying the `mysql.ndb_binlog_index' table directly on the
master. This can be also be accomplished using the `SHOW BINLOG EVENTS'
statement on either the replication master or slave MySQL servers. (See
*Note show-binlog-events::.)

You can also obtain useful information from the output of `SHOW ENGINE
NDB STATUS'.

The `ndb_schema' table is used to track schema changes made to `NDB'
tables. It is defined as shown here:

     CREATE TABLE ndb_schema (
         `db` VARBINARY(63) NOT NULL,
         `name` VARBINARY(63) NOT NULL,
         `slock` BINARY(32) NOT NULL,
         `query` BLOB NOT NULL,
         `node_id` INT UNSIGNED NOT NULL,
         `epoch` BIGINT UNSIGNED NOT NULL,
         `id` INT UNSIGNED NOT NULL,
         `version` INT UNSIGNED NOT NULL,
         `type` INT UNSIGNED NOT NULL,
         PRIMARY KEY USING HASH (db,name)
     ) ENGINE=NDB   DEFAULT CHARSET=latin1;

Unlike the two tables previously mentioned in this section, the
`ndb_schema' table is not visible either to MySQL `SHOW' statements, or
in any `INFORMATION_SCHEMA' tables; however, it can be seen in the
output of `ndb_show_tables', as shown here:

     shell> ndb_show_tables -t 2
     id    type                 state    logging database     schema   name
     4     UserTable            Online   Yes     mysql        def      ndb_apply_status
     5     UserTable            Online   Yes     ndbworld     def      City
     6     UserTable            Online   Yes     ndbworld     def      Country
     3     UserTable            Online   Yes     mysql        def      NDB$BLOB_2_3
     7     UserTable            Online   Yes     ndbworld     def      CountryLanguage
     _2     UserTable            Online   Yes     mysql        def      ndb_schema_

     NDBT_ProgramExit: 0 - OK

It is also possible to `SELECT' from this table in `mysql' and other
MySQL client applications, as shown here:

     mysql> SELECT * FROM mysql.ndb_schema WHERE name='City' \G
     *************************** 1. row ***************************
          db: ndbworld
        name: City
       slock:
       query: alter table City engine=ndb
     node_id: 4
       epoch: 0
          id: 0
     version: 0
        type: 7
     1 row in set (0.00 sec)

This can sometimes be useful when debugging applications.

*Note*:

When performing schema changes on `NDB' tables, applications should
wait until the `ALTER TABLE' statement has returned in the MySQL client
connection that issued the statement before attempting to use the
updated definition of the table.

The `ndb_schema' table was added in MySQL 5.1.8.

Beginning with MySQL 5.1.14, if either of the `ndb_apply_status' or
`ndb_schema' tables does not exist on the slave, it is created by
`ndb_restore'. (Bug#14612 (http://bugs.mysql.com/14612))

Conflict resolution for MySQL Cluster Replication requires the presence
of an additional `mysql.ndb_replication' table. Currently, this table
must be created manually. For details, see *Note
mysql-cluster-replication-conflict-resolution::.


File: manual.info,  Node: mysql-cluster-replication-preparation,  Next: mysql-cluster-replication-starting,  Prev: mysql-cluster-replication-schema,  Up: mysql-cluster-replication

20.11.5 Preparing the Cluster for Replication
---------------------------------------------

Preparing the MySQL Cluster for replication consists of the following
steps:

  1. Check all MySQL servers for version compatibility (see *Note
     mysql-cluster-replication-general::).

  2. Create a slave account on the master Cluster with the appropriate
     privileges:

          mysqlM> GRANT REPLICATION SLAVE
               -> ON *.* TO 'SLAVE_USER'@'SLAVE_HOST'
               -> IDENTIFIED BY 'SLAVE_PASSWORD';

     In the previous statement, SLAVE_USER is the slave account
     username, SLAVE_HOST is the hostname or IP address of the
     replication slave, and SLAVE_PASSWORD is the password to assign to
     this account.

     For example, to create a slave user account with the name
     ``myslave',' logging in from the host named ``rep-slave',' and
     using the password ``53cr37',' use the following `GRANT' statement:

          mysqlM> GRANT REPLICATION SLAVE
               -> ON *.* TO 'myslave'@'rep-slave'
               -> IDENTIFIED BY '53cr37';

     For security reasons, it is preferable to use a unique user
     account -- not employed for any other purpose -- for the
     replication slave account.

  3. Configure the slave to use the master. Using the MySQL Monitor,
     this can be accomplished with the `CHANGE MASTER TO' statement:

          mysqlS> CHANGE MASTER TO
               -> MASTER_HOST='MASTER_HOST',
               -> MASTER_PORT=MASTER_PORT,
               -> MASTER_USER='SLAVE_USER',
               -> MASTER_PASSWORD='SLAVE_PASSWORD';

     In the previous statement, MASTER_HOST is the hostname or IP
     address of the replication master, MASTER_PORT is the port for the
     slave to use for connecting to the master, SLAVE_USER is the
     username set up for the slave on the master, and SLAVE_PASSWORD is
     the password set for that user account in the previous step.

     For example, to tell the slave to replicate from the MySQL server
     whose hostname is ``rep-master',' using the replication slave
     account created in the previous step, use the following statement:

          mysqlS> CHANGE MASTER TO
               -> MASTER_HOST='rep-master'
               -> MASTER_PORT=3306,
               -> MASTER_USER='myslave'
               -> MASTER_PASSWORD='53cr37';

     For a complete list of clauses that can be used with this
     statement, see *Note change-master-to::.

     You can also configure the slave to use the master by setting the
     corresponding startup options in the slave server's `my.cnf' file.
     To configure the slave in the same way as the preceding example
     `CHANGE MASTER TO' statement, the following information would need
     to be included in the slave's `my.cnf' file:

          [mysqld]
          master-host=rep-master
          master-port=3306
          master-user=myslave
          master-password=53cr37

     For additional options that can be set in `my.cnf' for replication
     slaves, see *Note replication-options::.

     *Note*:

     To provide replication backup capability, you will also need to
     add an `ndb-connectstring' option to the slave's `my.cnf' file
     prior to starting the replication process. See *Note
     mysql-cluster-replication-backups::, for details.

  4. If the master cluster is already in use, you can create a backup
     of the master and load this onto the slave to cut down on the
     amount of time required for the slave to synchronize itself with
     the master. If the slave is also running MySQL Cluster, this can
     be accomplished using the backup and restore procedure described in
     *Note mysql-cluster-replication-backups::.

          ndb-connectstring=MANAGEMENT_HOST[:PORT]

     In the event that you are _not_ using MySQL Cluster on the
     replication slave, you can create a backup with this command on
     the replication master:

          shellM> mysqldump --master-data=1

     Then import the resulting data dump onto the slave by copying the
     dump file over to the slave. After this, you can use the `mysql'
     client to import the data from the dumpfile into the slave
     database as shown here, where DUMP_FILE is the name of the file
     that was generated using `mysqldump' on the master, and DB_NAME is
     the name of the database to be replicated:

          shellS> mysql -u root -p DB_NAME < DUMP_FILE

     For a complete list of options to use with `mysqldump', see *Note
     mysqldump::.

     *Note*:

     If you copy the data to the slave in this fashion, you should make
     sure that the slave is started with the `--skip-slave-start'
     option on the command line, or else include `skip-slave-start' in
     the slave's `my.cnf' file to keep it from trying to connect to the
     master to begin replicating before all the data has been loaded.
     Once the data loading has completed, follow the additional steps
     outlined in the next two sections.

  5. Ensure that each MySQL server acting as a replication master is
     configured with a unique server ID, and with binary logging
     enabled, using the row format. (See *Note replication-formats::.)
     These options can be set either in the master server's `my.cnf'
     file, or on the command line when starting the master `mysqld'
     process. See *Note mysql-cluster-replication-starting::, for
     information regarding the latter option.


File: manual.info,  Node: mysql-cluster-replication-starting,  Next: mysql-cluster-replication-two-channels,  Prev: mysql-cluster-replication-preparation,  Up: mysql-cluster-replication

20.11.6 Starting Replication (Single Replication Channel)
---------------------------------------------------------

This section outlines the procedure for starting MySQL CLuster
replication using a single replication channel.

  1. Start the MySQL replication master server by issuing this command:

          shellM> mysqld --ndbcluster --server-id=ID \
                  --log-bin --binlog-format=ROW &

     In the previous statement, ID is this server's unique ID (see
     *Note mysql-cluster-replication-general::). This starts the
     server's `mysqld' process with binary logging enabled using the
     proper logging format.

     *Note*:

     You can also start the master with `--binlog-format=MIXED', in
     which case row-based replication is used automatically when
     replicating between clusters.

  2. Start the MySQL replication slave server as shown here:

          shellS> mysqld --ndbcluster --server-id=ID &

     In the previous statement, ID is the slave server's unique ID. It
     is not necessary to enable logging on the replication slave.

     *Note*:

     You should use the `--skip-slave-start' option with this command
     or else you should include `skip-slave-start' in the slave server's
     `my.cnf' file, unless you want replication to begin immediately.
     With the use of this option, the start of replication is delayed
     until the appropriate `START SLAVE' statement has been issued, as
     explained in Step 4 below.

  3. It is necessary to synchronize the slave server with the master
     server's replication binlog. If binary logging has not previously
     been running on the master, run the following statement on the
     slave:

          mysqlS> CHANGE MASTER TO
               -> MASTER_LOG_FILE='',
               -> MASTER_LOG_POS=4;

     This instructs the slave to begin reading the master's binary log
     from the log's starting point. Otherwise -- that is, if you are
     loading data from the master using a backup -- see *Note
     mysql-cluster-replication-failover::, for information on how to
     obtain the correct values to use for `MASTER_LOG_FILE' and
     `MASTER_LOG_POS' in such cases.

  4. Finally, you must instruct the slave to begin applying replication
     by issuing this command from the `mysql' client on the replication
     slave:

          mysqlS> START SLAVE;

     This also initiates the transmission of replication data from the
     master to the slave.

It is also possible to use two replication channels, in a manner simlar
to the procedure described in the next section; the differences between
this and using a single replication channel are covered in *Note
mysql-cluster-replication-two-channels::.

Beginning with MySQL Cluster NDB 6.2.3, it is possible to improve
cluster replication performance by enabling _batched updates_. This can
be accomplished by starting slave `mysqld' processes with the
`--slave-allow-batching' option. Normally, updates are applied as soon
as they are received. However, the use of batching causes updates to be
applied in 32 KB batches, which can result in higher throughput and
less CPU usage, particularly where individual updates are relatively
small.

*Note*:

Slave batching works on a per-epoch basis; updates belonging to more
than one transaction can be sent as part of the same batch.

All outstanding updates are applied when the end of an epoch is
reached, even if the updates total less than 32 KB.

Batching can be turned on and off at runtime. To activate it at
runtime, you can use either of these two statements:

     SET GLOBAL slave_allow_batching = 1;
     SET GLOBAL slave_allow_batching = ON;

If a particular batch causes problems (such as a statement whose
effects do not appear to be replicated correctly), slave batching can
be deactivated using either of the following statements:

     SET GLOBAL slave_allow_batching = 0;
     SET GLOBAL slave_allow_batching = OFF;

You can check whether slave batching is currently being used by means
of an appropriate `SHOW VARIABLES' statement, like this one:

     mysql> SHOW VARIABLES LIKE 'slave%';
     +---------------------------+-------+
     | Variable_name             | Value |
     +---------------------------+-------+
     | slave_allow_batching      | ON    |
     | slave_compressed_protocol | OFF   |
     | slave_load_tmpdir         | /tmp  |
     | slave_net_timeout         | 3600  |
     | slave_skip_errors         | OFF   |
     | slave_transaction_retries | 10    |
     +---------------------------+-------+
     6 rows in set (0.00 sec)


File: manual.info,  Node: mysql-cluster-replication-two-channels,  Next: mysql-cluster-replication-failover,  Prev: mysql-cluster-replication-starting,  Up: mysql-cluster-replication

20.11.7 Using Two Replication Channels
--------------------------------------

In a more complete example scenario, we envision two replication
channels to provide redundancy and thereby guard against possible
failure of a single replication channel. This requires a total of four
replication servers, two masters for the master cluster and two slave
servers for the slave cluster. For purposes of the discussion that
follows, we assume that unique identifiers are assigned as shown here:

*Server ID*            *Description*
1                      Master - primary replication channel (_M_)
2                      Master - secondary replication channel (_M'_)
3                      Slave - primary replication channel (_S_)
4                      Slave - secondary replication channel (_S'_)

Setting up replication with two channels is not radically different
from setting up a single replication channel. First, the `mysqld'
processes for the primary and secondary replication masters must be
started, followed by those for the primary and secondary slaves. Then
the replication processes may be initiated by issuing the `START SLAVE'
statement on each of the slaves. The commands and the order in which
they need to be issued are shown here:

  1. Start the primary replication master:

          shellM> mysqld --ndbcluster --server-id=1 \
                         --log-bin --binlog-format=row &

  2. Start the secondary replication master:

          shellM'> mysqld --ndbcluster --server-id=2 \
                         --log-bin --binlog-format=row &

  3. Start the primary replication slave server:

          shellS> mysqld --ndbcluster --server-id=3 \
                         --skip-slave-start &

  4. Start the secondary replication slave:

          shellS'> mysqld --ndbcluster --server-id=4 \
                          --skip-slave-start &

  5. Finally, initiate replication on the primary channel by executing
     the `START SLAVE' statement on the primary slave as shown here:

          mysqlS> START SLAVE;

     *Warning*:

     Only the primary channel is to be started at this point.  The
     secondary replication channel is to be started only in the event
     that the primary replication channel fails, as described in *Note
     mysql-cluster-replication-failover::.  Running multiple
     replication channels simultaneously can result in unwanted
     duplicate records being created on the replication slaves.

As mentioned previously, it is not necessary to enable binary logging
on replication slaves.


File: manual.info,  Node: mysql-cluster-replication-failover,  Next: mysql-cluster-replication-backups,  Prev: mysql-cluster-replication-two-channels,  Up: mysql-cluster-replication

20.11.8 Implementing Failover with MySQL Cluster
------------------------------------------------

In the event that the primary Cluster replication process fails, it is
possible to switch over to the secondary replication channel. The
following procedure describes the steps required to accomplish this.

  1. Obtain the time of the most recent global checkpoint (GCP).  That
     is, you need to determine the most recent epoch from the
     `ndb_apply_status' table on the slave cluster, which can be found
     using the following query:

          mysqlS'> SELECT @latest:=MAX(epoch)
                ->        FROM mysql.ndb_apply_status;

  2. Using the information obtained from the query shown in Step 1,
     obtain the corresponding records from the `ndb_binlog_index' table
     on the master cluster as shown here:

          mysqlM'> SELECT
                ->     @file:=SUBSTRING_INDEX(File, '/', -1),
                ->     @pos:=Position
                -> FROM mysql.ndb_binlog_index
                -> WHERE epoch >= @latest
                -> ORDER BY epoch ASC LIMIT 1;

     These are the records saved on the master since the failure of the
     primary replication channel. We have employed a user variable
     `@latest' here to represent the value obtained in Step 1. Of
     course, it is not possible for one `mysqld' instance to access user
     variables set on another server instance directly. These values
     must be `plugged in' to the second query manually or in
     application code.

  3. Now it is possible to synchronize the secondary channel by running
     the following query on the secondary slave server:

          mysqlS'> CHANGE MASTER TO
                ->     MASTER_LOG_FILE='@file',
                ->     MASTER_LOG_POS=@pos;

     Again we have employed user variables (in this case `@file' and
     `@pos') to represent the values obtained in Step 2 and applied in
     Step 3; in practice these values must be inserted manually or using
     application code that can access both of the servers involved.

     *Note*:

     `@file' is a string value such as
     `'/var/log/mysql/replication-master-bin.00001'', and so must be
     quoted when used in SQL or application code.  However, the value
     represented by `@pos' must _not_ be quoted. Although MySQL
     normally attempts to convert strings to numbers, this case is an
     exception.

  4. You can now initiate replication on the secondary channel by
     issuing the appropriate command on the secondary slave `mysqld':

          mysqlS'> START SLAVE;

Once the secondary replication channel is active, you can investigate
the failure of the primary and effect repairs. The precise actions
required to do this will depend upon the reasons for which the primary
channel failed.

*Warning*:

The secondary replication channel is to be started only if and when the
primary replication channel has failed. Running multiple replication
channels simultaneously can result in unwanted duplicate records being
created on the replication slaves.

If the failure is limited to a single server, it should (in theory) be
possible to replicate from M to S', or from M' to S; however, this has
not yet been tested.


File: manual.info,  Node: mysql-cluster-replication-backups,  Next: mysql-cluster-replication-conflict-resolution,  Prev: mysql-cluster-replication-failover,  Up: mysql-cluster-replication

20.11.9 MySQL Cluster Backups With Replication
----------------------------------------------

* Menu:

* mysql-cluster-replication-auto-sync::  Automating Synchronization of the Slave to the Master binlog

This section discusses making backups and restoring from them using
MySQL Cluster replication. We assume that the replication servers have
already been configured as covered previously (see *Note
mysql-cluster-replication-preparation::, and the sections immediately
following). This having been done, the procedure for making a backup
and then restoring from it is as follows:

  1. There are two different methods by which the backup may be started.

        * Method A

          This method requires that the cluster backup process was
          previously enabled on the master server, prior to starting
          the replication process. This can be done by including the
          following line in a `[mysql_cluster]' section in the `my.cnf
          file', where MANAGEMENT_HOST is the IP address or hostname of
          the `NDB' management server for the master cluster, and PORT
          is the management server's port number:

               ndb-connectstring=MANAGEMENT_HOST[:PORT]

          *Note*:

          The port number needs to be specified only if the default
          port (1186) is not being used. See *Note
          mysql-cluster-multi-config::, for more information about
          ports and port allocation in MySQL Cluster.

          In this case, the backup can be started by executing this
          statement on the replication master:

               shellM> ndb_mgm -e "START BACKUP"

        * Method B

          If the `my.cnf' file does not specify where to find the
          management host, you can start the backup process by passing
          this information to the `NDB' management client as part of the
          `START BACKUP' command. This can be done as shown here, where
          MANAGEMENT_HOST and PORT are the hostname and port number of
          the management server:

               shellM> ndb_mgm MANAGEMENT_HOST:PORT -e "START BACKUP"

          In our scenario as outlined earlier (see *Note
          mysql-cluster-replication-preparation::), this would be
          executed as follows:

               shellM> ndb_mgm rep-master:1186 -e "START BACKUP"

  2. Copy the cluster backup files to the slave that is being brought
     on line. Each system running an `ndbd' process for the master
     cluster will have cluster backup files located on it, and _all_ of
     these files must be copied to the slave to ensure a successful
     restore. The backup files can be copied into any directory on the
     computer where the slave management host resides, so long as the
     MySQL and NDB binaries have read permissions in that directory. In
     this case, we will assume that these files have been copied into
     the directory `/var/BACKUPS/BACKUP-1'.

     It is not necessary that the slave cluster have the same number of
     `ndbd' processes (data nodes) as the master; however, it is highly
     recommended this number be the same. It _is_ necessary that the
     slave be started with the `--skip-slave-start' option, to prevent
     premature startup of the replication process.

  3. Create any databases on the slave cluster that are present on the
     master cluster that are to be replicated to the slave.

     *Important*:

     A `CREATE DATABASE' (or `CREATE SCHEMA') statement corresponding
     to each database to be replicated must be executed on each SQL
     node in the slave cluster.

  4. Reset the slave cluster using this statement in the MySQL Monitor:

          mysqlS> RESET SLAVE;

     It is important to make sure that the slave's `apply_status' table
     does not contain any records prior to running the restore process.
     You can accomplish this by running this SQL statement on the slave:

          mysqlS> DELETE FROM mysql.ndb_apply_status;

  5. You can now start the cluster restoration process on the
     replication slave using the `ndb_restore' command for each backup
     file in turn. For the first of these, it is necessary to include
     the `-m' option to restore the cluster metadata:

          shellS> ndb_restore -c SLAVE_HOST:PORT -n NODE-ID \
                  -b BACKUP-ID -m -r DIR

     DIR is the path to the directory where the backup files have been
     placed on the replication slave. For the `ndb_restore' commands
     corresponding to the remaining backup files, the `-m' option
     should _not_ be used.

     For restoring from a master cluster with four data nodes (as shown
     in the figure in *Note mysql-cluster-replication::) where the
     backup files have been copied to the directory
     `/var/BACKUPS/BACKUP-1', the proper sequence of commands to be
     executed on the slave might look like this:

          shellS> ndb_restore -c rep-slave:1186 -n 2 -b 1 -m \
                  -r ./var/BACKUPS/BACKUP-1
          shellS> ndb_restore -c rep-slave:1186 -n 3 -b 1 \
                  -r ./var/BACKUPS/BACKUP-1
          shellS> ndb_restore -c rep-slave:1186 -n 4 -b 1 \
                  -r ./var/BACKUPS/BACKUP-1
          shellS> ndb_restore -c rep-slave:1186 -n 5 -b 1 -e \
                  -r ./var/BACKUPS/BACKUP-1

     *Important*:

     The `-e' (or `--restore-epoch') option in the final invocation of
     `ndb_restore' in this example is required in order that the epoch
     is written to the slave `mysql.ndb_apply_status'. Without this
     information, the slave will not be able to synchronize properly
     with the master. (See *Note mysql-cluster-restore::.)

  6. Now you need to obtain the most recent epoch from the
     `ndb_apply_status' table on the slave (as discussed in *Note
     mysql-cluster-replication-failover::):

          mysqlS> SELECT @latest:=MAX(epoch)
                  FROM mysql.ndb_apply_status;

  7. Using `@latest' as the epoch value obtained in the previous step,
     you can obtain the correct starting position `@pos' in the correct
     binary log file `@file' from the master's `mysql.ndb_binlog_index'
     table using the query shown here:

          mysqlM> SELECT
               ->     @file:=SUBSTRING_INDEX(File, '/', -1),
               ->     @pos:=Position
               -> FROM mysql.ndb_binlog_index
               -> WHERE epoch > @latest
               -> ORDER BY epoch ASC LIMIT 1;

     In the event that there is currently no replication traffic, you
     can get this information by running `SHOW MASTER STATUS' on the
     master and using the value in the `Position' column for the file
     whose name has the suffix with the greatest value for all files
     shown in the `File' column. However, in this case, you must
     determine this and supply it in the next step manually or by
     parsing the output with a script.

  8. Using the values obtained in the previous step, you can now issue
     the appropriate `CHANGE MASTER TO' statement in the slave's
     `mysql' client:

          mysqlS> CHANGE MASTER TO
               ->     MASTER_LOG_FILE='@file',
               ->     MASTER_LOG_POS=@pos;

  9. Now that the slave `knows' from what point in which `binlog' file
     to start reading data from the master, you can cause the slave to
     begin replicating with this standard MySQL statement:

          mysqlS> START SLAVE;

To perform a backup and restore on a second replication channel, it is
necessary only to repeat these steps, substituting the hostnames and
IDs of the secondary master and slave for those of the primary master
and slave replication servers where appropriate, and running the
preceding statements on them.

For additional information on performing Cluster backups and restoring
Cluster from backups, see *Note mysql-cluster-backup::.


File: manual.info,  Node: mysql-cluster-replication-auto-sync,  Prev: mysql-cluster-replication-backups,  Up: mysql-cluster-replication-backups

20.11.9.1 Automating Synchronization of the Slave to the Master binlog
......................................................................

It is possible to automate much of the process described in the
previous section (see *Note mysql-cluster-replication-backups::). The
following Perl script `reset-slave.pl' serves as an example of how you
can do this.

     #!/user/bin/perl -w

     #  file: reset-slave.pl

     #  Copyright (C)2005 MySQL AB

     #  This program is free software; you can redistribute it and/or modify
     #  it under the terms of the GNU General Public License as published by
     #  the Free Software Foundation; either version 2 of the License, or
     #  (at your option) any later version.

     #  This program is distributed in the hope that it will be useful,
     #  but WITHOUT ANY WARRANTY; without even the implied warranty of
     #  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     #  GNU General Public License for more details.

     #  You should have received a copy of the GNU General Public License
     #  along with this program; if not, write to:
     #  Free Software Foundation, Inc.
     #  59 Temple Place, Suite 330
     #  Boston, MA 02111-1307 USA
     #
     #  Version 1.1

     ######################## Includes ###############################

     use DBI;

     ######################## Globals ################################

     my  $m_host='';
     my  $m_port='';
     my  $m_user='';
     my  $m_pass='';
     my  $s_host='';
     my  $s_port='';
     my  $s_user='';
     my  $s_pass='';
     my  $dbhM='';
     my  $dbhS='';

     ####################### Sub Prototypes ##########################

     sub CollectCommandPromptInfo;
     sub ConnectToDatabases;
     sub DisconnectFromDatabases;
     sub GetSlaveEpoch;
     sub GetMasterInfo;
     sub UpdateSlave;

     ######################## Program Main ###########################

     CollectCommandPromptInfo;
     ConnectToDatabases;
     GetSlaveEpoch;
     GetMasterInfo;
     UpdateSlave;
     DisconnectFromDatabases;

     ################## Collect Command Prompt Info ##################

     sub CollectCommandPromptInfo
     {
       ### Check that user has supplied correct number of command line args
       die "Usage:\n
            reset-slave >master MySQL host< >master MySQL port< \n
                        >master user< >master pass< >slave MySQL host< \n
                        >slave MySQL port< >slave user< >slave pass< \n
            All 8 arguments must be passed. Use BLANK for NULL passwords\n"
            unless @ARGV == 8;

       $m_host  =  $ARGV[0];
       $m_port  =  $ARGV[1];
       $m_user  =  $ARGV[2];
       $m_pass  =  $ARGV[3];
       $s_host  =  $ARGV[4];
       $s_port  =  $ARGV[5];
       $s_user  =  $ARGV[6];
       $s_pass  =  $ARGV[7];

       if ($m_pass eq "BLANK") { $m_pass = '';}
       if ($s_pass eq "BLANK") { $s_pass = '';}
     }

     ###############  Make connections to both databases #############

     sub ConnectToDatabases
     {
       ### Connect to both master and slave cluster databases

       ### Connect to master
       $dbhM
         = DBI->connect(
         "dbi:mysql:database=mysql;host=$m_host;port=$m_port",
         "$m_user", "$m_pass")
           or die "Can't connect to Master Cluster MySQL process!
                   Error: $DBI::errstr\n";

       ### Connect to slave
       $dbhS
         = DBI->connect(
               "dbi:mysql:database=mysql;host=$s_host",
               "$s_user", "$s_pass")
         or die "Can't connect to Slave Cluster MySQL process!
                 Error: $DBI::errstr\n";
     }

     ################  Disconnect from both databases ################

     sub DisconnectFromDatabases
     {
       ### Disconnect from master

       $dbhM->disconnect
       or warn " Disconnection failed: $DBI::errstr\n";

       ### Disconnect from slave

       $dbhS->disconnect
       or warn " Disconnection failed: $DBI::errstr\n";
     }

     ######################  Find the last good GCI ##################

     sub GetSlaveEpoch
     {
       $sth = $dbhS->prepare("SELECT MAX(epoch)
                              FROM mysql.ndb_apply_status;")
           or die "Error while preparing to select epoch from slave: ",
                  $dbhS->errstr;

       $sth->execute
           or die "Selecting epoch from slave error: ", $sth->errstr;

       $sth->bind_col (1, \$epoch);
       $sth->fetch;
       print "\tSlave Epoch =  $epoch\n";
       $sth->finish;
     }

     #######  Find the position of the last GCI in the binlog ########

     sub GetMasterInfo
     {
       $sth = $dbhM->prepare("SELECT
                                SUBSTRING_INDEX(File, '/', -1), Position
                              FROM mysql.ndb_binlog_index
                              WHERE epoch > $epoch
                              ORDER BY epoch ASC LIMIT 1;")
           or die "Prepare to select from master error: ", $dbhM->errstr;

       $sth->execute
           or die "Selecting from master error: ", $sth->errstr;

       $sth->bind_col (1, \$binlog);
       $sth->bind_col (2, \$binpos);
       $sth->fetch;
       print "\tMaster bin log =  $binlog\n";
       print "\tMaster Bin Log position =  $binpos\n";
       $sth->finish;
     }

     ##########  Set the slave to process from that location #########

     sub UpdateSlave
     {
       $sth = $dbhS->prepare("CHANGE MASTER TO
                              MASTER_LOG_FILE='$binlog',
                              MASTER_LOG_POS=$binpos;")
           or die "Prepare to CHANGE MASTER error: ", $dbhS->errstr;

       $sth->execute
            or die "CHANGE MASTER on slave error: ", $sth->errstr;
       $sth->finish;
       print "\tSlave has been updated. You may now start the slave.\n";
     }

     # end reset-slave.pl


File: manual.info,  Node: mysql-cluster-replication-conflict-resolution,  Prev: mysql-cluster-replication-backups,  Up: mysql-cluster-replication

20.11.10 MySQL Cluster Replication Conflict Resolution
------------------------------------------------------

When using a replication setup involving multiple masters (including
circular replication), it is possible that different masters may try to
update the same row on the slave with different data. Conflict
resolution in MySQL Cluster Replication provides a means of resolving
such conflicts by allowing a user defined resolution column to be used
to determine whether or not an update to the row on a given master
should be applied on the slave. (This column is sometimes referred to
as a `timestamp' column, even though this column' type cannot be
`TIMESTAMP', as explained later in this section.)  Different methods
can be used to compare resolution column values on the slave when
conflicts occur, as explained later in this section; the method used
can be set on a per-table basis.

*Important*:

Conflict resolution as described in this section is always applied on a
row-by-row basis rather than a transactional basis.  In addition, it is
the application's responsibility to ensure that the resolution column
is correctly populated with relevant values, so that the resolution
function can make the appropriate choice when determining whether to
apply an update.

Requirements

Preparations for conflict resolution must be made on both the master
and the slave:

   * On the master writing the binlogs, you must determine which
     columns are sent (all columns or only those that have been
     updated). This is done for the MySQL Server as a whole by applying
     the `mysqld' startup option `--ndb-log-updated-only' (described
     later in this section) or on a per-table basis by entries in the
     `mysql.ndb_replication' table.

   * On the slave, you must determine which type of conflict resolution
     to apply (`latest timestamp wins', `same timestamp wins', or
     none). This is done using the `mysql.ndb_replication' system
     table, on a per-table basis.

If only some but not all columns are sent, then the master and slave
can diverge.

*Note*:

We refer to the column used for determining updates as a `timestamp'
column, but the data type of this column is never `TIMESTAMP'; rather,
its data type should be `INT' (`INTEGER') or `BIGINT'. This column
should be `UNSIGNED' and `NOT NULL'.

Master column control

We can see update operations in terms of `before' and `after' images --
that is, the states of the table before and after the update is
applied. Normally, when updating a table with a primary key, the
`before' image is not of great interest; however, when we need to
determine on a per-update basis whether or not to use the updated
values on a replication slave, we need to make sure that both images
are written to the master's binary log. This is done with the
`--ndb-log-update-as-write' startup option for `mysqld', as described
later in this section.

*Important*:

Whether logging of complete rows or of updated columns only is done is
decided when the MySQL server is started, and cannot be changed online;
you must either restart `mysqld', or start a new `mysqld' instance with
different logging options.

Logging full or partial rows (`--ndb-log-updated-only' option)

For purposes of conflict resolution, there are two basic methods of
logging rows, as determined by the setting of the
`--ndb-log-updated-only' option for `mysqld':

   * Log complete rows

   * Log only column data that has been updated -- that is, column data
     whose value has been set, regardless of whether or not this value
     was actually changed.

It is more efficient to log updated columns only; however, if you need
to log full rows, you can do so by setting `--ndb-log-updated-only' to
`0' or `OFF'.

Logging changed data as updates (`--ndb-log-update-as-write' option)

Either of these logging methods can be configured to be done with or
without the `before' image as determined by the setting of another
MySQL Server option `--ndb-log-update-as-write'. Because conflict
resolution is done in the MySQL Server's update handler, it is
necessary to control logging on the master such that updates are
updates and not writes; that is, such that updates are treated as
changes in existing rows rather than the writing of new rows (even
though these replace existing rows). This option is turned on by
default; to turn it off, start the server with
`--ndb-log-update-as-write=0' or `--ndb-log-update-as-write=OFF'.

Conflict resolution control

Conflict resolution is usually enabled on the server where conflicts
can occur. Like logging method selection, it is enabled by entries in
the `mysql.ndb_replication' table.

The `ndb_replication' system table

To enable conflict resolution, it is necessary to create an
`ndb_replication' table in the `mysql' system database on the master,
the slave, or both, depending on the conflict resolution type and
method to be employed. This table is used to control logging and
conflict resolution functions on a per-table basis, and has one row per
table invoved in replication.  `ndb_replication' is created and filled
with control information on the server where the conflict is to be
resolved. In a simple master-slave setup where data can also be changed
locally on the slave this will typically be the slave.  In a more
complex master-master (2-way) replication schema this will usually be
all of the masters involved. Each row in `mysql.ndb_replication'
corresponds to a table being replicated, and specifies how to log and
resolve conflicts (that is, which conflict resolution function, if any,
to use) for that table. The definition of the `mysql.ndb_replication'
table is shown here:

     CREATE TABLE mysql.ndb_replication  (
         db VARBINARY(63),
         table_name VARBINARY(63),
         server_id INT UNSIGNED,
         binlog_type INT UNSIGNED,
         conflict_fn VARBINARY(128),
         PRIMARY KEY USING HASH (db, table_name, server_id)
     )   ENGINE=NDB
     PARTITION BY KEY(db,table_name);

The columns in this table are described in the following list:

   * `db'

     The name of the database containing the table to be replicated.

   * `table_name'

     The name of the table to be replicated.

   * `server_id'

     The unique server ID of the MySQL instance (SQL node) where the
     table resides.

   * `binlog_type'

     The type of binary logging to be employed. This is determined as
     shown in the following table:

     Value      Internal Value       Description
     0          `NBT_DEFAULT'        Use server default
     1          `NBT_NO_LOGGING'     Do not log this table in the binary
                                     log
     2          `NBT_UPDATED_ONLY'   Only updated attributes are logged
     3          `NBT_FULL'           Log full row, even if not updated
                                     (MySQL server default behavior)
     4          `NBT_USE_UPDATE'     (For generating
                                     `NBT_UPDATED_ONLY_USE_UPDATE' and
                                     `NBT_FULL_USE_UPDATE' values only --
                                     not intended for separate use)
     5          [_Not used_]         --
     6          `NBT_UPDATED_ONLY_USE_UPDATE'Use updated attributes, even if
                (equal to            values are unchanged
                `NBT_UPDATED_ONLY |  
                NBT_USE_UPDATE')     
     7          `NBT_FULL_USE_UPDATE'Use full row, even if values are
                (equal to `NBT_FULL  unchanged
                | NBT_USE_UPDATE')   

   * `conflict_fn'

     The conflict resolution function to be applied. This function must
     be specified as one of the following:

        * `NDB$MAX(COLUMN_NAME')

          Indicates that `greatest timestamp wins' conflict resolution
          is to be used -- that is, if the `timestamp' for a given row
          coming from the master is higher than that on the slave, it
          is applied; otherwise it is not applied on the slave. This
          ensures that, in the event of a conflict, the version of the
          row that was most recently updated is the version that
          persists.

          This conflict resolution function is available beginning with
          MySQL Cluster NDB 6.3.0.

        * `NDB$OLD(COLUMN_NAME')

          Indicates that an update is applied only if the value of
          COLUMN_NAME is the same on both the master and the slave.
          This ensures that updates are not applied from the wrong
          master.

          This conflict resolution function is available beginning with
          MySQL Cluster NDB 6.3.4.

        * `NULL': Indicates that conflict resolution is not to be used
          for the corresponding table

     .

Status information

Beginning with MySQL Cluster NDB 6.3.3, a server status variable
`Ndb_conflict_fn_max' provides a count of the number of times that a
row was not applied on the current SQL node due to `greatest timestamp
wins' conflict resolution since the last time that `mysqld' was started.

Beginning with MySQL Cluster NDB 6.3.4, the number of times that a row
was not applied as the result of `same timestamp wins' conflict
resolution on a given `mysqld' since the last time it was restarted is
given by the global status variable `Ndb_conflict_fn_old'. In addition
to incrementing `Ndb_conflict_fn_old', the primary key of the row that
was not used is inserted into an _exceptions table_, as explained later
in this section.

Additional requirements for `Same timestamp wins' conflict resolution

To use the `NDB$OLD()' conflict resolution function, it is also
necessary to create an exceptions table corresponding to each `NDB'
table for which this type of conflict resolution is to be employed. The
name of this table is that of the table for which `same timestamp wins'
conflict resolution is to be applied, with the string `$EX' appended.
(For example, if the name of the original table is `mytable', the name
of the corresponding exception table name should be `mytable$EX'.) This
table is created as follows:

     CREATE TABLE ORIGINAL_TABLE$EX  (
         server_id INT UNSIGNED,
         master_server_id INT UNSIGNED,
         master_epoch BIGINT UNSIGNED,
         count INT UNSIGNED,
         ORIGINAL_TABLE_PK_COLUMNS,
         [ADDITIONAL_COLUMNS,]
         PRIMARY KEY(server_id, master_server_id, master_epoch, count)
     ) ENGINE=NDB;

The first four columns are required. Following these columns, the
columns making up the original table's primary key should be copied in
the order in which they are used to define the primary key of the
original table.

*Note*:

The names of the first four columns and the columns matching the
original table's primary key columns are not critical; however, we
suggest for reasons of clarity and consistency, that you use the names
shown here for the `server_id', `master_server_id', `master_epoch', and
`count' columns, and that you use the same names as in the original
table for the columns matching those in the original table's primary
key.

The data types for the columns duplicating the primary key columns of
the original table should be the same as for (or larger than) the
original columns.

Additional columns may optionally be defined following these columns,
but not before any of them; any such extra columns cannot be `NOT
NULL'. The exception table's primary key must be defined as shown. The
exception table must use the `NDB' storage engine. An example of use
for `NDB$OLD()' and an exception table is given later in this section.

*Important*:

The `mysql.ndb_replication' table is read when a data table is set up
for replication, so the row corresponding to a table to be replicated
must be inserted into `mysql.ndb_replication' _before_ the table to be
replicated is created.

Examples

The following examples assume that you have already a working MySQL
Cluster replication setup, as described in *Note
mysql-cluster-replication-preparation::, and *Note
mysql-cluster-replication-starting::.

   * `NDB$MAX()' example

     Suppose you wish to enable `greatest timestamp wins' conflict
     resolution on table `test.t1', using column `mycol' as the
     `timestamp'. This can be done using the following steps:

       1. Make sure that you have started the master `mysqld' with
          `--ndb-log-update-as-write=OFF'.

       2. On the master, perform this `INSERT' statement:

               INSERT INTO mysql.ndb_replication
                   VALUES ('test', 't1', 0, NULL, 'NDB$MAX(mycol)');

          Inserting a 0 into the `server_id' indicates that all SQL
          nodes accessing this table should use conflict resolution. If
          you want to use conflict resolution on a specific `mysqld'
          only, use the actual server ID.

          Inserting `NULL' into the `binlog_type' column has the same
          effect as inserting 0 (`NBT_DEFAULT'); the server default is
          used.

       3. Create the `test.t1' table:

               CREATE TABLE test.t1 (
                   COLUMNS
                   mycol INT UNSIGNED,
                   COLUMNS
               ) ENGINE=NDB;

          Now, when updates are done on this table, conflict resolution
          will be applied, and the version of the row having the
          greatest value for `mycol' will be written to the slave.

     *Note*:

     Other `binlog_type' options -- such as
     `NBT_UPDATED_ONLY_USE_UPDATE' should be used in order to control
     logging on the master via the `ndb_replication' table rather than
     by using command-line options.

   * `NDB$OLD()' example

     Suppose an `NDB' table such as the one defined here is being
     replicated, and you wish to enable `same timestamp wins' conflict
     resolution for updates to this table:

          CREATE TABLE test.t2  (
              a INT UNSIGNED NOT NULL,
              b CHAR(25) NOT NULL,
              COLUMNS,
              mycol INT UNSIGNED NOT NULL,
              COLUMNS,
              PRIMARY KEY pk (a, b)
          )   ENGINE=NDB;

     The following steps are required, in the order shown:

       1. First -- and _prior_ to creating `test.t2' -- you must insert
          a row into the `mysql.ndb_replication' table, as shown here:

               INSERT INTO mysql.ndb_replication
                   VALUES ('test', 't2', 0, NULL, 'NDB$OLD(mycol)');

          Possible values for the `binlog_type' column are shown
          earlier in this section. The value `'NDB$OLD(mycol)'' should
          be inserted into the `conflict_fn' column.

       2. Create an appropriate exceptions table for `test.t2'. The
          table creation statement shown here includes all required
          columns; any additional columns must be declared following
          these columns, and before the definition of the table's
          primary key.

               CREATE TABLE test.t2$EX  (
                   server_id SMALLINT UNSIGNED,
                   master_server_id SMALLINT UNSIGNED,
                   master_epoch BIGINT UNSIGNED,
                   count BIGINT UNSIGNED,
                   a INT UNSIGNED NOT NULL,
                   b CHAR(25) NOT NULL,
                   [ADDITIONAL_COLUMNS,]
                   PRIMARY KEY(server_id, master_server_id, master_epoch, count)
               )   ENGINE=NDB;

       3. Create the table `test.t2' as shown previously.

     These steps must be followed for every table for which you wish to
     perform conflict resolution using `NDB$OLD()'. For each such
     table, there must be a corresponding row in
     `mysql.ndb_replication', and there must be an exceptions table in
     the same database as the table being replicated.


File: manual.info,  Node: mysql-cluster-disk-data,  Next: mysql-cluster-interconnects,  Prev: mysql-cluster-replication,  Up: mysql-cluster

20.12 MySQL Cluster Disk Data Tables
====================================

* Menu:

* mysql-cluster-disk-data-objects::  Disk Data Objects
* mysql-cluster-disk-data-storage-requirements::  Disk Data Storage Requirements
* mysql-cluster-disk-data-parameters::  Disk Data Configuration Parameters

Beginning with MySQL 5.1.6, it is possible to store the non-indexed
columns of `NDB' tables on disk, rather than in RAM as with previous
versions of MySQL Cluster.

As part of implementing Cluster Disk Data work, a number of
improvements were made in MySQL Cluster for the efficient handling of
very large amounts (terabytes) of data during node recovery and
restart. These include a `no-steal' algorithm for synchronising a
starting node with very large data sets. For more information, see the
paper Recovery Principles of MySQL Cluster 5.1
(http://www.vldb2005.org/program/paper/wed/p1108-ronstrom.pdf), by
MySQL Cluster developers Mikael Ronstro"m and Jonas Oreland.


File: manual.info,  Node: mysql-cluster-disk-data-objects,  Next: mysql-cluster-disk-data-storage-requirements,  Prev: mysql-cluster-disk-data,  Up: mysql-cluster-disk-data

20.12.1 Disk Data Objects
-------------------------

This section discusses Disk Data objects -- which include tables, log
file groups, and tablespaces -- as well as how to create and drop them.

Assuming that you have already set up a MySQL Cluster with all nodes
(including management and SQL nodes) running MySQL 5.1.6 or newer, the
basic steps for creating a Cluster table on disk are as follows:

  1. Create a _log file group_, and assign one or more undo log files
     to it (an undo log file is also referred as an _undofile_).

     *Note*:

     In MySQL 5.1, undo log files are necessary only for Disk Data
     tables. They are no longer used for tables that are stored in
     memory.

  2. Create a _tablespace_, and assign the log file group to it, as
     well as one or more data files.

  3. Create a Disk Data table that uses this tablespace for data
     storage.

Each of these tasks can be accomplished using SQL statements, as shown
in the following example.

  1. We create a log file group named `lg_1' using `CREATE LOGFILE
     GROUP'. This log file group is to be made up of two undo log
     files, which we name `undo_1.dat' and `undo_2.dat', whose initial
     sizes are 16 MB and 12 MB, respectively. (The default initial size
     for an undo log file is 128 MB.) Optionally, you can also specify
     a size for the log file group's `UNDO' buffer, or allow it to
     assume the default value of 8 MB. In this example, we set the UNDO
     buffer's size at 2 MB. A log file group must be created with an
     undo log file; so we add `undo_1.dat' to `lg_1' in this `CREATE
     LOGFILE GROUP' statement:

          CREATE LOGFILE GROUP lg_1
              ADD UNDOFILE 'undo_1.dat'
              INITIAL_SIZE 16M
              UNDO_BUFFER_SIZE 2M
              ENGINE NDB;

     To add `undo_2.dat' to the log file group, use the following
     `ALTER LOGFILE GROUP' statement:

          ALTER LOGFILE GROUP lg_1
              ADD UNDOFILE 'undo_2.dat'
              INITIAL_SIZE 12M
              ENGINE NDB;

     Some items of note:

        * The `.dat' file extension used here is not required. We use
          it merely to make the log and data files easily recognisable.

        * Every `CREATE LOGFILE GROUP' and `ALTER LOGFILE GROUP'
          statement must include an `ENGINE' clause. In MySQL 5.1, the
          permitted values for this clause are `NDB' and `NDBCLUSTER'.

          *Important*:

          In MySQL 5.1.8 and later, there can exist only one log file
          group at any given time.

        * When you add an undo log file to a log file group using `ADD
          UNDOFILE 'FILENAME'', a file with the name FILENAME is
          created in the `ndb_NODEID_fs' directory within the
          `DataDirectory' of each data node in the cluster, where
          NODEID is the node ID of the data node.

        * `UNDO_BUFFER_SIZE' is limited by the amount of system memory
          available.

        * For more information about the `CREATE LOGFILE GROUP'
          statement, see *Note create-logfile-group::. For more
          information about `ALTER LOGFILE GROUP', see *Note
          alter-logfile-group::.

  2. Now we can create a tablespace, which contains files to be used by
     MySQL Cluster Disk Data tables for storing their data.  A
     tablespace is also associated with a particular log file group.
     When creating a new tablespace, you must specify the log file
     group which it is to use for undo logging; you must also specify a
     data file. You can add more data files to the tablespace after the
     tablespace is created; it is also possible to drop data files from
     a tablespace (an example of dropping data files is provided later
     in this section).

     Assume that we wish to create a tablespace named `ts_1' which uses
     `lg_1' as its log file group. This tablespace is to contain two
     data files named `data_1.dat' and `data_2.dat', whose initial
     sizes are 32 MB and 48 MB, respectively. (The default value for
     `INITIAL_SIZE' is 128 MB.) We can do this using two SQL
     statements, as shown here:

          CREATE TABLESPACE ts_1
              ADD DATAFILE 'data_1.dat'
              USE LOGFILE GROUP lg_1
              INITIAL_SIZE 32M
              ENGINE NDB;

          ALTER TABLESPACE ts_1
              ADD DATAFILE 'data_2.dat'
              INITIAL_SIZE 48M
              ENGINE NDB;

     The `CREATE TABLESPACE' statement creates a tablespace `ts_1' with
     the data file `data_1.dat', and associates `ts_1' with log file
     group `lg_1'. The `ALTER TABLESPACE' adds the second data file
     (`data_2.dat').

     Some items of note:

        * As is the case with the filenames used here for undo log
          files, there is no special significance for the `.dat' file
          extension; it is used merely for easy recognition.

        * All `CREATE TABLESPACE' and `ALTER TABLESPACE' statements must
          contain an `ENGINE' clause; only tables using the same
          storage engine as the tablespace can be created in the
          tablespace. In MySQL 5.1, the only permitted values for this
          clause are `NDB' and `NDBCLUSTER'.

          For more information about the `CREATE TABLESPACE' and `ALTER
          TABLESPACE' statements, see *Note create-tablespace::, and
          *Note alter-tablespace::.

  3. Now it is possible to create a table whose non-indexed columns are
     stored on disk in the tablespace `ts_1':

          CREATE TABLE dt_1 (
              member_id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
              last_name VARCHAR(50) NOT NULL,
              first_name VARCHAR(50) NOT NULL,
              dob DATE NOT NULL,
              joined DATE NOT NULL,
              INDEX(last_name, first_name)
              )
              TABLESPACE ts_1 STORAGE DISK
              ENGINE NDB;

     The `TABLESPACE ... STORAGE DISK' clause tells the `NDBCLUSTER'
     storage engine to use tablespace `ts_1' for disk data storage.

     *Note*:

     Beginning with MySQL Cluster NDB 6.2.5 and MySQL Cluster NDB
     6.3.2, it is also possible to specify whether an individual column
     is stored on disk or in memory by using a `STORAGE' clause as part
     of the column's definition in a `CREATE TABLE' or `ALTER TABLE'
     statement. `STORAGE DISK' causes the column to be stored on disk,
     and `STORAGE MEMORY' causes in-memory storage to be used. See
     *Note create-table::, for more information.

     Once table `ts_1' has been created as shown, you can perform
     `INSERT', `SELECT', `UPDATE', and `DELETE' statements on it just
     as you would with any other MySQL table.

     For table `dt_1' as it has been defined here, only the `dob' and
     `joined' columns are stored on disk. This is because there are
     indexes on the `id', `last_name', and `first_name' columns, and so
     data belonging to these columns is stored in RAM. In MySQL 5.1,
     only non-indexed columns can be held on disk; indexes and indexed
     column data continue to be stored in memory. This tradeoff between
     the use of indexes and conservation of RAM is something you must
     keep in mind as you design Disk Data tables.

Performance note

The performance of a cluster using Disk Data storage is greatly
improved if Disk Data files are kept on a separate physical disk from
the data node filesystem. This must be done for each data node in the
cluster to derive any noticeable benefit.

You may use absolute and relative filesystem paths with `ADD UNDOFILE'
and `ADD DATAFILE'. Relative paths are calculated relative to the data
node's data directory.

A log file group, a tablespace, and any Disk Data tables using these
must be created in a particular order. The same is true for dropping
any of these objects:

   * A log file group cannot be dropped, so long as any tablespaces are
     using it.

   * A tablespace cannot be dropped as long as it contains any data
     files.

   * You cannot drop any data files from a tablespace as long as there
     remain any tables which are using the tablespace.

   * Beginning with MySQL 5.1.12, it is no longer possible to drop
     files created in association with a different tablespace than the
     one with which the files were created. (Bug#20053
     (http://bugs.mysql.com/20053))

For example, to drop all the objects created so far in this section,
you would use the following statements:

     mysql> DROP TABLE dt_1;

     mysql> ALTER TABLESPACE ts_1
         -> DROP DATAFILE 'data_2.dat'
         -> ENGINE NDB;

     mysql> ALTER TABLESPACE ts_1
         -> DROP DATAFILE 'data_1.dat'
         -> ENGINE NDB;

     mysql> DROP TABLESPACE ts_1
         -> ENGINE NDB;

     mysql> DROP LOGFILE GROUP lg_1
         -> ENGINE NDB;

These statements must be performed in the order shown, except that the
two `ALTER TABLESPACE ... DROP DATAFILE' statements may be executed in
either order.

You can obtain information about data files used by Disk Data tables by
querying the `FILES' table in the `INFORMATION_SCHEMA' database. An
extra ``NULL' row' was added to this table in MySQL 5.1.14 for
providing additional information about undo log files. For more
information and examples of use, see *Note files-table::.


File: manual.info,  Node: mysql-cluster-disk-data-storage-requirements,  Next: mysql-cluster-disk-data-parameters,  Prev: mysql-cluster-disk-data-objects,  Up: mysql-cluster-disk-data

20.12.2 Disk Data Storage Requirements
--------------------------------------

The following items apply to Disk Data storage requirements:

   * Variable-length columns of Disk Data tables take up a fixed amount
     of space. For each row, this is equal to the space required to
     store the largest possible value for that column.

     For general information about calculating these values, see *Note
     storage-requirements::.

   * In a Disk Data table, the first 256 bytes of a `TEXT' or `BLOB'
     column are stored in memory; only the remainder is stored on disk.

*Important*:

Starting the cluster with the `--initial' option does _not_ remove Disk
Data files. You must remove these manually prior to performing an
initial restart of the cluster.


File: manual.info,  Node: mysql-cluster-disk-data-parameters,  Prev: mysql-cluster-disk-data-storage-requirements,  Up: mysql-cluster-disk-data

20.12.3 Disk Data Configuration Parameters
------------------------------------------

Configuration parameters affecting Disk Data behaviour include the
following:

   * `DiskPageBufferMemory'

     This determines the amount of space used for caching pages on
     disk, and is set in the `[ndbd]' or `[ndbd default]' section of the
     `config.ini' file. It is measured in bytes. Each page takes up 32
     KB. This means that Cluster Disk Data storage always uses N * 32
     KB memory where N is some non-negative integer.

   * `SharedGlobalMemory'

     This determines the amount of memory that is used for log buffers,
     disk operations (such as page requests and wait queues), and
     metadata for tablespaces, log file groups, `UNDO' files, and data
     files. It can be set in the `[ndbd]' or `[ndbd default]' section
     of the `config.ini' configuration file, and is measured in bytes.

     The default value is `20M'.

These parameters were added in MySQL 5.1.6

*Note*:

The `OPTIMIZE TABLE' statement does not have any effect on Disk Data
tables.


File: manual.info,  Node: mysql-cluster-interconnects,  Next: mysql-cluster-limitations,  Prev: mysql-cluster-disk-data,  Up: mysql-cluster

20.13 Using High-Speed Interconnects with MySQL Cluster
=======================================================

* Menu:

* mysql-cluster-sci-sockets::    Configuring MySQL Cluster to use SCI Sockets
* mysql-cluster-interconnects-performance::  MySQL Cluster Interconnects and Performance

Even before design of `NDBCLUSTER' began in 1996, it was evident that
one of the major problems to be encountered in building parallel
databases would be communication between the nodes in the network. For
this reason, `NDBCLUSTER' was designed from the very beginning to allow
for the use of a number of different data transport mechanisms. In this
Manual, we use the term _transporter_ for these.

The MySQL Cluster codebase includes support for four different
transporters:

   * _TCP/IP using 100 Mbps or gigabit Ethernet_, as discussed in *Note
     mysql-cluster-tcp-definition::.

   * _Direct (machine-to-machine) TCP/IP_; although this transporter
     uses the same TCP/IP protocol as mentioned in the previous item,
     it requires setting up the hardware differently and is configured
     differently as well. For this reason, it is considered a separate
     transport mechanism for MySQL Cluster. See *Note
     mysql-cluster-tcp-definition-direct::, for details.

   * _Shared memory (SHM)_. For more information about SHM, see *Note
     mysql-cluster-shm-definition::.

   * _Scalable Coherent Interface (SCI)_, as described in the next
     section of this chapter, *Note mysql-cluster-sci-definition::.

Most users today employ TCP/IP over Ethernet because it is ubiquitous.
TCP/IP is also by far the best-tested transporter for use with MySQL
Cluster.

We are working to make sure that communication with the `ndbd' process
is made in `chunks' that are as large as possible because this benefits
all types of data transmission.

For users who desire it, it is also possible to use cluster
interconnects to enhance performance even further. There are two ways
to achieve this: Either a custom transporter can be designed to handle
this case, or you can use socket implementations that bypass the TCP/IP
stack to one extent or another. We have experimented with both of these
techniques using the SCI (Scalable Coherent Interface) technology
developed by Dolphin (http://www.dolphinics.com/).


File: manual.info,  Node: mysql-cluster-sci-sockets,  Next: mysql-cluster-interconnects-performance,  Prev: mysql-cluster-interconnects,  Up: mysql-cluster-interconnects

20.13.1 Configuring MySQL Cluster to use SCI Sockets
----------------------------------------------------

In this section, we show how to adapt a cluster configured for normal
TCP/IP communication to use SCI Sockets instead. This documentation is
based on SCI Sockets version 2.3.0 as of 01 October 2004.

Prerequisites

Any machines with which you wish to use SCI Sockets must be equipped
with SCI cards.

No special builds (other than the `-max' builds) are needed for SCI
Sockets because it uses normal TCP/IP socket calls which are already
available in MySQL Cluster. However, SCI Sockets are currently
supported only on the Linux 2.4 and 2.6 kernels. For other operating
systems, you can use SCI Transporters, but this requires that the
server be built using `--with-ndb-sci=/opt/DIS'.

Prior to MySQL 5.1.20, there were issues with building MySQL Cluster
with SCI support (see Bug#25470 (http://bugs.mysql.com/25470)), but
these have been resolved due to work contributed by Dolphin
International. SCI Sockets are now correctly supported for MySQL
Cluster using the `-max' builds, and versions of MySQL Cluster with SCI
Transporter support can be built using either of
`compile-amd64-max-sci' or `compile-pentium64-max-sci'. Both of these
build scripts can be found in the `BUILD' directory of the MySQL 5.1
source; it should not be difficult to adapt them for other platforms.

There are essentially four requirements for SCI Sockets:

   * Building the SCI Socket libraries.

   * Installation of the SCI Socket kernel libraries.

   * Installation of one or two configuration files.

   * The SCI Socket kernel library must be enabled either for the
     entire machine or for the shell where the MySQL Cluster processes
     are started.

This process needs to be repeated for each machine in the cluster where
you plan to use SCI Sockets for inter-node communication.

Two packages need to be retrieved to get SCI Sockets working:

   * The source code package containing the DIS support libraries for
     the SCI Sockets libraries.

   * The source code package for the SCI Socket libraries themselves.

Currently, these are available only in source code format. The latest
versions of these packages at the time of this writing were available
as (respectively) `DIS_GPL_2_5_0_SEP_10_2004.tar.gz' and
`SCI_SOCKET_2_3_0_OKT_01_2004.tar.gz'. You should be able to find these
(or possibly newer versions) at
`http://www.dolphinics.com/support/downloads.html'.

Package Installation

Once you have obtained the library packages, the next step is to unpack
them into appropriate directories, with the SCI Sockets library
unpacked into a directory below the DIS code. Next, you need to build
the libraries. This example shows the commands used on Linux/x86 to
perform this task:

     shell> tar xzf DIS_GPL_2_5_0_SEP_10_2004.tar.gz
     shell> cd DIS_GPL_2_5_0_SEP_10_2004/src/
     shell> tar xzf ../../SCI_SOCKET_2_3_0_OKT_01_2004.tar.gz
     shell> cd ../adm/bin/Linux_pkgs
     shell> ./make_PSB_66_release

It is possible to build these libraries for some 64-bit processors. To
build the libraries for Opteron CPUs using the 64-bit extensions, run
`make_PSB_66_X86_64_release' rather than `make_PSB_66_release'. If the
build is made on an Itanium machine, you should use
`make_PSB_66_IA64_release'. The X86-64 variant should work for Intel
EM64T architectures but this has not yet (to our knowledge) been tested.

Once the build process is complete, the compiled libraries will be
found in a zipped tar file with a name along the lines of
`DIS-<OPERATING-SYSTEM>-TIME-DATE'.  It is now time to install the
package in the proper place. In this example we will place the
installation in `/opt/DIS'. You most likely need to run the following
as the system `root' user.

     shell> cp DIS_Linux_2.4.20-8_181004.tar.gz /opt/
     shell> cd /opt
     shell> tar xzf DIS_Linux_2.4.20-8_181004.tar.gz
     shell> mv DIS_Linux_2.4.20-8_181004 DIS

Network configuration

Now that all the libraries and binaries are in their proper place, we
need to ensure that the SCI cards have proper node IDs within the SCI
address space.

It is also necessary to decide on the network structure before
proceeding. There are three types of network structures which can be
used in this context:

   * A simple one-dimensional ring

   * One or more SCI switches with one ring per switch port

   * A two- or three-dimensional torus.

Each of these topologies has its own method for providing node IDs. We
discuss each of them in brief.

A simple ring uses node IDs which are non-zero multiples of 4: 4, 8,
12,...

The next possibility uses SCI switches. An SCI switch has 8 ports, each
of which can support a ring. It is necessary to make sure that
different rings use different node ID spaces. In a typical
configuration, the first port uses node IDs below 64 (4 - 60), the next
64 node IDs (68 - 124) are assigned to the next port, and so on, with
node IDs 452 - 508 being assigned to the eighth port.

Two- and three-dimensional torus network structures take into account
where each node is located in each dimension, incrementing by 4 for
each node in the first dimension, by 64 in the second dimension, and
(where applicable) by 1024 in the third dimension.  See Dolphin's Web
site (http://www.dolphinics.com/support/index.html) for more thorough
documentation.

In our testing we have used switches, although most large cluster
installations use 2- or 3-dimensional torus structures. The advantage
provided by switches is that, with dual SCI cards and dual switches, it
is possible to build with relative ease a redundant network where the
average failover time on the SCI network is on the order of 100
microseconds. This is supported by the SCI transporter in MySQL Cluster
and is also under development for the SCI Socket implementation.

Failover for the 2D/3D torus is also possible but requires sending out
new routing indexes to all nodes. However, this requires only 100
milliseconds or so to complete and should be acceptable for most
high-availability cases.

By placing cluster data nodes properly within the switched
architecture, it is possible to use 2 switches to build a structure
whereby 16 computers can be interconnected and no single failure can
hinder more than one of them. With 32 computers and 2 switches it is
possible to configure the cluster in such a manner that no single
failure can cause the loss of more than two nodes; in this case, it is
also possible to know which pair of nodes is affected. Thus, by placing
the two nodes in separate node groups, it is possible to build a `safe'
MySQL Cluster installation.

To set the node ID for an SCI card use the following command in the
`/opt/DIS/sbin' directory. In this example, `-c 1' refers to the number
of the SCI card (this is always 1 if there is only 1 card in the
machine); `-a 0' refers to adapter 0; and `68' is the node ID:

     shell> ./sciconfig -c 1 -a 0 -n 68

If you have multiple SCI cards in the same machine, you can determine
which card has which slot by issuing the following command (again we
assume that the current working directory is `/opt/DIS/sbin'):

     shell> ./sciconfig -c 1 -gsn

This will give you the SCI card's serial number. Then repeat this
procedure with `-c 2', and so on, for each card in the machine. Once
you have matched each card with a slot, you can set node IDs for all
cards.

After the necessary libraries and binaries are installed, and the SCI
node IDs are set, the next step is to set up the mapping from hostnames
(or IP addresses) to SCI node IDs. This is done in the SCI sockets
configuration file, which should be saved as `/etc/sci/scisock.conf'.
In this file, each SCI node ID is mapped through the proper SCI card to
the hostname or IP address that it is to communicate with. Here is a
very simple example of such a configuration file:

     #host           #nodeId
     alpha           8
     beta            12
     192.168.10.20   16

It is also possible to limit the configuration so that it applies only
to a subset of the available ports for these hosts. An additional
configuration file `/etc/sci/scisock_opt.conf' can be used to
accomplish this, as shown here:

     #-key                        -type        -values
     EnablePortsByDefault                yes
     EnablePort                  tcp           2200
     DisablePort                 tcp           2201
     EnablePortRange             tcp           2202 2219
     DisablePortRange            tcp           2220 2231

Driver installation

With the configuration files in place, the drivers can be installed.

First, the low-level drivers and then the SCI socket driver need to be
installed:

     shell> cd DIS/sbin/
     shell> ./drv-install add PSB66
     shell> ./scisocket-install add

If desired, the installation can be checked by invoking a script which
verifies that all nodes in the SCI socket configuration files are
accessible:

     shell> cd /opt/DIS/sbin/
     shell> ./status.sh

If you discover an error and need to change the SCI socket
configuration, it is necessary to use `ksocketconfig' to accomplish
this task:

     shell> cd /opt/DIS/util
     shell> ./ksocketconfig -f

For more information about `ksocketconfig', consult the documentation
available from `http://www.dolphinics.com/support/documentation.html'.

Testing the setup

To ensure that SCI sockets are actually being used, you can employ the
`latency_bench' test program. Using this utility's server component,
clients can connect to the server to test the latency of the
connection. Determining whether SCI is enabled should be fairly simple
from observing the latency.

*Note*:

Before using `latency_bench', it is necessary to set the `LD_PRELOAD'
environment variable as shown later in this section.

To set up a server, use the following:

     shell> cd /opt/DIS/bin/socket
     shell> ./latency_bench -server

To run a client, use `latency_bench' again, except this time with the
`-client' option:

     shell> cd /opt/DIS/bin/socket
     shell> ./latency_bench -client SERVER_HOSTNAME

SCI socket configuration should now be complete and MySQL Cluster ready
to use both SCI Sockets and the SCI transporter (see *Note
mysql-cluster-sci-definition::).

Starting the cluster

The next step in the process is to start MySQL Cluster. To enable usage
of SCI Sockets it is necessary to set the environment variable
`LD_PRELOAD' before starting `ndbd', `mysqld', and `ndb_mgmd'. This
variable should point to the kernel library for SCI Sockets.

To start `ndbd' in a bash shell, do the following:

     bash-shell> export LD_PRELOAD=/opt/DIS/lib/libkscisock.so
     bash-shell> ndbd

In a tcsh environment the same thing can be accomplished with:

     tcsh-shell> setenv LD_PRELOAD=/opt/DIS/lib/libkscisock.so
     tcsh-shell> ndbd

*Note*:

MySQL Cluster can use only the kernel variant of SCI Sockets.


File: manual.info,  Node: mysql-cluster-interconnects-performance,  Prev: mysql-cluster-sci-sockets,  Up: mysql-cluster-interconnects

20.13.2 MySQL Cluster Interconnects and Performance
---------------------------------------------------

The `ndbd' process has a number of simple constructs which are used to
access the data in a MySQL Cluster.  We have created a very simple
benchmark to check the performance of each of these and the effects
which various interconnects have on their performance.

There are four access methods:

   * Primary key access

     This is access of a record through its primary key. In the
     simplest case, only one record is accessed at a time, which means
     that the full cost of setting up a number of TCP/IP messages and a
     number of costs for context switching are borne by this single
     request. In the case where multiple primary key accesses are sent
     in one batch, those accesses share the cost of setting up the
     necessary TCP/IP messages and context switches. If the TCP/IP
     messages are for different destinations, additional TCP/IP
     messages need to be set up.

   * Unique key access

     Unique key accesses are similar to primary key accesses, except
     that a unique key access is executed as a read on an index table
     followed by a primary key access on the table.  However, only one
     request is sent from the MySQL Server, and the read of the index
     table is handled by `ndbd'. Such requests also benefit from
     batching.

   * Full table scan

     When no indexes exist for a lookup on a table, a full table scan
     is performed. This is sent as a single request to the `ndbd'
     process, which then divides the table scan into a set of parallel
     scans on all cluster `ndbd' processes. In future versions of MySQL
     Cluster, an SQL node will be able to filter some of these scans.

   * *Range scan using ordered index*

     When an ordered index is used, it performs a scan in the same
     manner as the full table scan, except that it scans only those
     records which are in the range used by the query transmitted by
     the MySQL server (SQL node). All partitions are scanned in
     parallel when all bound index attributes include all attributes in
     the partitioning key.

With benchmarks developed internally by MySQL for testing simple and
batched primary and unique key accesses, we have found that using SCI
sockets improves performance by approximately 100% over TCP/IP, except
in rare instances when communication performance is not an issue. This
can occur when scan filters make up most of processing time or when
very large batches of primary key accesses are achieved. In that case,
the CPU processing in the `ndbd' processes becomes a fairly large part
of the overhead.

Using the SCI transporter instead of SCI Sockets is only of interest in
communicating between `ndbd' processes. Using the SCI transporter is
also only of interest if a CPU can be dedicated to the `ndbd' process
because the SCI transporter ensures that this process will never go to
sleep. It is also important to ensure that the `ndbd' process priority
is set in such a way that the process does not lose priority due to
running for an extended period of time, as can be done by locking
processes to CPUs in Linux 2.6. If such a configuration is possible, the
`ndbd' process will benefit by 10-70% as compared with using SCI
sockets. (The larger figures will be seen when performing updates and
probably on parallel scan operations as well.)

There are several other optimized socket implementations for computer
clusters, including Myrinet, Gigabit Ethernet, Infiniband and the VIA
interface. However, we have tested MySQL Cluster so far only with SCI
sockets. See *Note mysql-cluster-sci-sockets::, for information on how
to set up SCI sockets using ordinary TCP/IP for MySQL Cluster.


File: manual.info,  Node: mysql-cluster-limitations,  Next: mysql-cluster-roadmap,  Prev: mysql-cluster-interconnects,  Up: mysql-cluster

20.14 Known Limitations of MySQL Cluster
========================================

* Menu:

* mysql-cluster-limitations-syntax::  Non-Compliance In SQL Syntax
* mysql-cluster-limitations-limits::  Limits and Differences from Standard MySQL Limits
* mysql-cluster-limitations-transactions::  Limits Relating to Transaction Handling
* mysql-cluster-limitations-error-handling::  Error Handling
* mysql-cluster-limitations-database-objects::  Limits Associated with Database Objects
* mysql-cluster-limitations-unsupported-missing::  Unsupported Or Missing Features
* mysql-cluster-limitations-performance::  Limitations Relating to Performance
* mysql-cluster-limitations-exclusive-to-cluster::  Issues Exclusive to MySQL Cluster
* mysql-cluster-limitations-disk-data::  Limitations Relating to Disk Data Storage
* mysql-cluster-limitations-multiple-nodes::  Limitations Relating to Multiple Cluster Nodes
* mysql-cluster-limitations-resolved::  Previous MySQL Cluster Issues Resolved in MySQL 5.1

In the sections that follow, we discuss known limitations in current
releases pf MySQL Cluster as compared with the features available when
using the `MyISAM' and `InnoDB' storage engines. If you check the
`Cluster' category in the MySQL bugs database at
`http://bugs.mysql.com', you can find known bugs in the following
categories under `MySQL Server:' in the MySQL bugs database at
`http://bugs.mysql.com', which we intend to correct in upcoming
releases of MySQL Cluster:

   * Cluster

   * Cluster Direct API (NDBAPI)

   * Cluster Disk Data

   * Cluster Replication

This information is intended to be complete with respect to the
conditions just set forth. You can report any discrepancies that you
encounter to the MySQL bugs database using the instructions given in
*Note bug-reports::. If we do not plan to fix the problem in MySQL 5.1,
we will add it to the list.

See *Note mysql-cluster-limitations-resolved:: for a list of issues in
MySQL Cluster in MySQL 5.0 that have been resolved in the current
version.

*Note*:

Limitations and other issues specific to MySQL Cluster Replication are
described in *Note mysql-cluster-replication-issues::.


File: manual.info,  Node: mysql-cluster-limitations-syntax,  Next: mysql-cluster-limitations-limits,  Prev: mysql-cluster-limitations,  Up: mysql-cluster-limitations

20.14.1 Non-Compliance In SQL Syntax
------------------------------------

Some SQL statements relating to certain MySQL features produce errors
when used with `NDB' tables, as described in the following list:

   * Temporary tables

     Temporary tables are not supported. Trying either to create a
     temporary table that uses the `NDB' storage engine or to alter an
     existing temporary table to use `NDB' fails with the error `Table
     storage engine 'ndbcluster' does not support the create option
     'TEMPORARY''.

   * Indexes and keys in `NDB' tables

     Keys and indexes on MySQL Cluster tables are subject to the
     following limitations:

        * `TEXT' and `BLOB' columns

          You cannot create indexes on `NDB' table columns that use any
          of the `TEXT' or `BLOB' data types.

        * `FULLTEXT' indexes

          The `NDB' storage engine does not support `FULLTEXT' indexes,
          which are possible for `MyISAM' tables only.

          However, you can create indexes on `VARCHAR' columns of `NDB'
          tables.

        * `BIT' columns

          A `BIT' column cannot be a primary key, unique key, or index,
          nor can it be part of a composite primary key, unique key, or
          index.

        * `AUTO_INCREMENT' columns

          Like other MySQL storage engines, the `NDB' storage engine
          can handle a maximum of one `AUTO_INCREMENT' column per
          table. However, in the case of a Cluster table with no
          explicit primary key, an `AUTO_INCREMENT' column is
          automatically defined and used as a `hidden' primary key. For
          this reason, you cannot define a table that has an explicit
          `AUTO_INCREMENT' column unless that column is also declared
          using the `PRIMARY KEY' option. Attempting to create a table
          with an `AUTO_INCREMENT' column that is not the table's
          primary key, and using the `NDB' storage engine, fails with
          an error.

   * MySQL Cluster and geometry data types

     Geometry datatypes (`WKT' and `WKB') are supported in `NDB' tables
     in MySQL 5.1.  However, spatial indexes are not supported.

   * Creating `NDB' tables with user-defined partitioning

     Support for user-defined partitioning for MySQL Cluster in MySQL
     5.1 is restricted to [`LINEAR'] `KEY' partitioning. Beginning with
     MySQL 5.1.12, using any other partitioning type with `ENGINE=NDB'
     or `ENGINE=NDBCLUSTER' in a `CREATE TABLE' statement results in an
     error.

     Default partitioning scheme

     As of MySQL 5.1.6, all Cluster tables are by default partitioned
     by `KEY' using the table's primary key as the partitioning key. If
     no primary key is explicitly set for the table, the `hidden'
     primary key automatically created by the `NDB' storage engine is
     used instead. For additional discussion of these and related
     issues, see *Note partitioning-key::.

     `DROP PARTITION' not supported

     It is not possible to drop partitions from `NDB' tables using
     `ALTER TABLE ... DROP PARTITION'. The other partitioning
     extensions to `ALTER TABLE' -- `ADD PARTITION', `REORGANIZE
     PARTITION', and `COALESCE PARTITION' -- are supported for Cluster
     tables, but use copying and so are not optimised. See *Note
     partitioning-management-range-list:: and *Note alter-table::.

   * Row-based replication

     When using row-based replication with MySQL Cluster, binary
     logging cannot be disabled. That is, the `NDB' storage engine
     ignores the value of `SQL_LOG_BIN'. (Bug#16680
     (http://bugs.mysql.com/16680))


File: manual.info,  Node: mysql-cluster-limitations-limits,  Next: mysql-cluster-limitations-transactions,  Prev: mysql-cluster-limitations-syntax,  Up: mysql-cluster-limitations

20.14.2 Limits and Differences from Standard MySQL Limits
---------------------------------------------------------

In this section, we list limits found in MySQL Cluster that either
differ from limits found in, or that are not found in, standard MySQL.

   * Memory usage and recovery

     Memory consumed when data is inserted into an `NDB' table is not
     automatically recovered when deleted, as it is with other storage
     engines. Instead, the following rules hold true:

        * A `DELETE' statement on an `NDB' table makes the memory
          formerly used by the deleted rows available for re-use by
          inserts on the same table only. This memory cannot be used by
          other `NDB' tables.

        * A `DROP TABLE' or `TRUNCATE' operation on an `NDB' table
          frees the memory that was used by this table for re-use by any
          `NDB' table, either by the same table or by another `NDB'
          table.

          *Note*:

          Recall that `TRUNCATE' drops and re-creates the table. See
          *Note truncate::.

          Memory freed by `DELETE' operations but still allocated to a
          specific table can also be made available for general re-use
          by performing a rolling restart of the cluster. See *Note
          mysql-cluster-rolling-restart::.

          Beginning with MySQL Cluster NDB 6.3.7, this limitation can
          be overcome using `OPTIMIZE TABLE'. See *Note
          mysql-cluster-limitations-resolved::, for more information.

        * Limits imposed by the cluster's configuration

          A number of hard limits exist which are configurable, but
          available main memory in the cluster sets limits. See the
          complete list of configuration parameters in *Note
          mysql-cluster-config-file::. Most configuration parameters
          can be upgraded online.  These hard limits include:

             * Database memory size and index memory size (`DataMemory'
               and `IndexMemory', respectively).

               `DataMemory' is allocated as 32KB pages. As each
               `DataMemory' page is used, it is assigned to a specific
               table; once allocated, this memory cannot be freed
               except by dropping the table.

               See *Note mysql-cluster-ndbd-definition::, for further
               information about `DataMemory' and `IndexMemory'.

             * The maximum number of operations that can be performed
               per transaction is set using the configuration parameters
               `MaxNoOfConcurrentOperations' and
               `MaxNoOfLocalOperations'.

               *Note*:

               Bulk loading, `TRUNCATE TABLE', and `ALTER TABLE' are
               handled as special cases by running multiple
               transactions, and so are not subject to this limitation.

             * Different limits related to tables and indexes. For
               example, the maximum number of ordered indexes per table
               is determined by `MaxNoOfOrderedIndexes'.

        * Node and data object maximums

          The following limits apply to numbers of cluster nodes and
          metadata objects:

             * The maximum number of data nodes is 48.

               A data node must have a node ID in the range of 1‐49,
               inclusive. (Management and API nodes may use any integer
               in the range of 1‐63 inclusive as a node ID.)

             * The total maximum number of nodes in a MySQL Cluster is
               63. This number includes all SQL nodes (MySQL Servers),
               API nodes (applications accessing the cluster other than
               MySQL servers), data nodes, and management servers.

             * The maximum number of metadata objects in current
               versions of MySQL Cluster. This limit is hard-coded.

          See *Note mysql-cluster-limitations-resolved::, for more
          information.


File: manual.info,  Node: mysql-cluster-limitations-transactions,  Next: mysql-cluster-limitations-error-handling,  Prev: mysql-cluster-limitations-limits,  Up: mysql-cluster-limitations

20.14.3 Limits Relating to Transaction Handling
-----------------------------------------------

A number of limitations exist in MySQL Cluster with regard to the
handling of transactions. These include the following:

   * Transaction isolation level

     The `NDBCLUSTER' storage engine supports only the `READ COMMITTED'
     transaction isolation level. (`InnoDB', for example, supports
     `READ COMMITTED', `READ UNCOMMITTED', `REPEATABLE READ', and
     `SERIALIZABLE'.) See *Note mysql-cluster-backup-troubleshooting::,
     for information on how this can affect backing up and restoring
     Cluster databases.)

     *Important*:

     If a `SELECT' from a Cluster table includes a `BLOB' or `TEXT'
     column, the `READ COMMITTED' transaction isolation level is
     converted to a read with read lock. This is done to guarantee
     consistency, due to the fact that parts of the values stored in
     columns of these types are actually read from a separate table.

   * Rollbacks

     There are no partial transactions, and no partial rollbacks of
     transactions. A duplicate key or similar error aborts the entire
     transaction, and subsequent statements raise `ERROR 1296 (HY000):
     Got error 4350 'Transaction already aborted' from NDBCLUSTER'. In
     such cases, you must issue an explicit `ROLLBACK' and retry the
     entire transaction.

     This behavior differs from that of other transactional storage
     engines such as `InnoDB' that may roll back individual statements.

   * Transactions and memory usage

     As noted elsewhere in this chapter, MySQL Cluster does not handle
     large transactions well; it is better to perform a number of small
     transactions with a few operations each than to attempt a single
     large transaction containing a great many operations. Among other
     considerations, large transactions require very large amounts of
     memory. Because of this, the transactional behaviour of a number
     of MySQL statements is effected as described in the following list:

        * `TRUNCATE' is not transactional when used on `NDB' tables. If
          a `TRUNCATE' fails to empty the table, then it must be re-run
          until it is successful.

        * `DELETE FROM' (even with no `WHERE' clause) _is_
          transactional. For tables containing a great many rows, you
          may find that performance is improved by using several
          `DELETE FROM ... LIMIT ...' statements to `chunk' the delete
          operation. If your objective is to empty the table, then you
          may wish to use `TRUNCATE' instead.

        * `LOAD DATA' statements

          `LOAD DATA INFILE' is not transactional when used on `NDB'
          tables.

          *Important*:

          When executing a `LOAD DATA INFILE' statement, the `NDB'
          engine performs commits at irregular intervals that enable
          better utilization of the communication network. It is not
          possible to know ahead of time when such commits take place.

          `LOAD DATA FROM MASTER' is not supported in MySQL Cluster.

        * `ALTER TABLE' and transactions

          When copying an `NDB' table as part of an `ALTER TABLE', the
          creation of the copy is non-transactional. (In any case, this
          operation is rolled back when the copy is deleted.)

   * Transactions and the `COUNT()' function

     When using MySQL Cluster Replication, it is not possible to
     guarantee the transactional consistency of the `COUNT()' function
     on the slave. In other words, when performing on the master a
     series of statements (`INSERT', `DELETE', or both) that changes the
     number of rows in a table within a single transaction, executing
     `SELECT COUNT(*) FROM TABLE' queries on the slave may yield
     intermediate results. This is due to the fact that `SELECT
     COUNT(...)' may perform dirty reads, and is not a bug in the `NDB'
     storage engine. (See Bug#31321 (http://bugs.mysql.com/31321) for
     more information.)


File: manual.info,  Node: mysql-cluster-limitations-error-handling,  Next: mysql-cluster-limitations-database-objects,  Prev: mysql-cluster-limitations-transactions,  Up: mysql-cluster-limitations

20.14.4 Error Handling
----------------------

Starting, stopping, or restarting a node may give rise to temporary
errors causing some transactions to fail. These include the following
cases:

   * Temporary errors

     When first starting a node, it is possible that you may see Error
     1204 `Temporary failure, distribution changed' and similar
     temporary errors.

   * Errors due to node failure

     The stopping or failure of any data node can result in a number of
     different node failure errors. (However, there should be no
     aborted transactions when performing a planned shutdown of the
     cluster.)

In either of these cases, any errors that are generated must be handled
within the application. This should be done by retrying the transaction.

See also *Note mysql-cluster-limitations-limits::.


File: manual.info,  Node: mysql-cluster-limitations-database-objects,  Next: mysql-cluster-limitations-unsupported-missing,  Prev: mysql-cluster-limitations-error-handling,  Up: mysql-cluster-limitations

20.14.5 Limits Associated with Database Objects
-----------------------------------------------

Some database objects such as tables and indexes have different
limitations when using the `NDBCLUSTER' storage engine:

   * Identifiers

     Database names, table names and attribute names cannot be as long
     in `NDB' tables as when using other table handlers. Attribute
     names are truncated to 31 characters, and if not unique after
     truncation give rise to errors. Database names and table names can
     total a maximum of 122 characters. In other words, the maximum
     length for an `NDB' table name is 122 characters, less the number
     of characters in the name of the database of which that table is a
     part.

   * Table names containing special characters

     `NDB' tables whose names contain characters other than letters,
     numbers, dashes, and underscores and which are created on one SQL
     node were not always discovered correctly by other SQL nodes.
     (Bug#31470 (http://bugs.mysql.com/31470))

     *Note*:

     This issue was fixed in MySQL 5.1.23, MySQL Cluster NDB 6.2.7, and
     MySQL Cluster NDB 6.3.4.

   * Number of tables

     The maximum number of `NDB' tables is limited to 20320.

   * Attributes per table

     The maximum number of attributes (that is, columns and indexes)
     per table is limited to 128.

   * Attributes per key

     The maximum number of attributes per key is 32.

   * Row size

     The maximum permitted size of any one row is 8KB. Note that each
     `BLOB' or `TEXT' column contributes 256 + 8 = 264 bytes towards
     this total.


File: manual.info,  Node: mysql-cluster-limitations-unsupported-missing,  Next: mysql-cluster-limitations-performance,  Prev: mysql-cluster-limitations-database-objects,  Up: mysql-cluster-limitations

20.14.6 Unsupported Or Missing Features
---------------------------------------

A number of features supported by other storage engines are not
supported for `NDB' tables. Trying to use any of these features in
MySQL Cluster does not cause errors in or of itself; however, errors
may occur in applications that expects the features to be supported or
enforced:

   * Foreign key constraints

     The foreign key construct is ignored, just as it is in `MyISAM'
     tables.

   * `OPTIMIZE' operations

     `OPTIMIZE' operations are not supported.

     Beginning with MySQL Cluster NDB 6.3.7, this limitation has been
     lifted. See *Note mysql-cluster-limitations-resolved::, for more
     information.

   * `LOAD TABLE ... FROM MASTER'

     `LOAD TABLE ... FROM MASTER' is not supported.

   * Savepoints and rollbacks

     Savepoints and rollbacks to savepoints are ignored as in `MyISAM'.

   * Durability of commits

     There are no durable commits on disk. Commits are replicated, but
     there is no guarantee that logs are flushed to disk on commit.

   * Replication

     Statement-based replication is not supported. Use
     -binlog-format=ROW (or -binlog-format=MIXED) when setting up
     cluster replication. See *Note mysql-cluster-replication::, for
     more information.

*Note*:

See *Note mysql-cluster-limitations-transactions::, for more
information relating to limitations on transaction handling in `NDB'.


File: manual.info,  Node: mysql-cluster-limitations-performance,  Next: mysql-cluster-limitations-exclusive-to-cluster,  Prev: mysql-cluster-limitations-unsupported-missing,  Up: mysql-cluster-limitations

20.14.7 Limitations Relating to Performance
-------------------------------------------

The following performance issues are specific to or especially
pronounced in MySQL Cluster:

   * Range scans

     There are query performance issues due to sequential access to the
     `NDB' storage engine; it is also relatively more expensive to do
     many range scans than it is with either `MyISAM' or `InnoDB'.

   * Reliability of `Records in range'

     The `Records in range' statistic is available but is not
     completely tested or officially supported. This may result in
     non-optimal query plans in some cases. If necessary, you can
     employ `USE INDEX' or `FORCE INDEX' to alter the execution plan.
     See *Note index-hints::, for more information on how to do this.

   * Unique hash indexes

     Unique hash indexes created with `USING HASH' cannot be used for
     accessing a table if `NULL' is given as part of the key.


File: manual.info,  Node: mysql-cluster-limitations-exclusive-to-cluster,  Next: mysql-cluster-limitations-disk-data,  Prev: mysql-cluster-limitations-performance,  Up: mysql-cluster-limitations

20.14.8 Issues Exclusive to MySQL Cluster
-----------------------------------------

The following are limitations specific to the `NDBCLUSTER' storage
engine:

   * Machine architecture

     All machines used in the cluster must have the same architecture.
     That is, all machines hosting nodes must be either big-endian or
     little-endian, and you cannot use a mixture of both. For example,
     you cannot have a management node running on a PowerPC which
     directs a data node that is running on an x86 machine. This
     restriction does not apply to machines simply running `mysql' or
     other clients that may be accessing the cluster's SQL nodes.

   * Adding and dropping of data nodes

     Online adding or dropping of data nodes is not currently possible.
     In such cases, the entire cluster must be restarted.

   * Binary logging

     MySQL Cluster has the following limitations or restrictions with
     regard to binary logging:

        * `SQL_LOG_BIN' has no effect on data operations; however, it
          is supported for schema operations.

        * MySQL Cluster cannot produce a binlog for tables having
          `BLOB' columns but no primary key.

        * Only the following schema operations are logged in a cluster
          binlog which is _not_ on the `mysqld' executing the statement:

             * `CREATE TABLE'

             * `ALTER TABLE'

             * `DROP TABLE'

             * `CREATE DATABASE' / `CREATE SCHEMA'

             * `DROP DATABASE' / `DROP SCHEMA'

             * `CREATE TABLESPACE'

             * `ALTER TABLESPACE'

             * `DROP TABLESPACE'

             * `CREATE LOGFILE GROUP'

             * `ALTER LOGFILE GROUP'

             * `DROP LOGFILE GROUP'

See also *Note mysql-cluster-limitations-multiple-nodes::.


File: manual.info,  Node: mysql-cluster-limitations-disk-data,  Next: mysql-cluster-limitations-multiple-nodes,  Prev: mysql-cluster-limitations-exclusive-to-cluster,  Up: mysql-cluster-limitations

20.14.9 Limitations Relating to Disk Data Storage
-------------------------------------------------

   * Disk data objects are subject to the following maximums:

        * Maximum number of tablespaces: 2^32 (4294967296)

        * Maximum number of data files per tablespace: 2^16 (65535)

        * The theoretical maximum number of extents per tablespace data
          file is 2^16 (65525); however, for practical purposes, the
          recommended maximum number of extents per data file is 2^8
          (32768).

        * Maximum data file size: The theoretical limit is 64G;
          however, in MySQL 5.1, the practical upper limit is 32G. This
          is equivalent to 32768 extents of 1M each.

          The minimum and maximum possible sizes of extents for
          tablespace data files are 32K and 2G, respectively. See *Note
          create-tablespace::, for more information.

   * Use of Disk Data tables is not supported when running the cluster
     in diskless mode. Beginning with MySQL 5.1.12, it is disallowed
     altogether. (Bug#20008 (http://bugs.mysql.com/20008))


File: manual.info,  Node: mysql-cluster-limitations-multiple-nodes,  Next: mysql-cluster-limitations-resolved,  Prev: mysql-cluster-limitations-disk-data,  Up: mysql-cluster-limitations

20.14.10 Limitations Relating to Multiple Cluster Nodes
-------------------------------------------------------

Multiple SQL nodes

The following are issues relating to the use of multiple MySQL servers
as MySQL Cluster SQL nodes, and are specific to the `NDBCLUSTER'
storage engine:

   * No distributed table locks

     A `LOCK TABLES' works only for the SQL node on which the lock is
     issued; no other SQL node in the cluster `sees' this lock. This is
     also true for a lock issued by any statement that locks tables as
     part of its operations. (See next item for an example.)

   * `ALTER TABLE' operations

     `ALTER TABLE' is not fully locking when running multiple MySQL
     servers (SQL nodes). (As discussed in the previous item, MySQL
     Cluster does not support distributed table locks.)

   * DDL operations

     DDL operations (such as `CREATE TABLE' or `ALTER TABLE') are not
     safe from data node failures. If a data node fails while trying to
     peform one of these, the data dictionary is locked and no further
     DDL statements can be executed without restarting the cluster.

Multiple management nodes

When using multiple management servers:

   * You must give nodes explicit IDs in connectstrings because
     automatic allocation of node IDs does not work across multiple
     management servers.

   * You must take extreme care to have the same configurations for all
     management servers. No special checks for this are performed by
     the cluster.

Multiple data node processes

While it is possible to run multiple cluster processes concurrently on
a single host, it is not always advisable to do so for reasons of
performance and high availability, as well as other considerations. In
particular, in MySQL 5.1 and MySQL Cluster NDB 6.x, we do not support
for production use any MySQL Cluster deployment in which more than one
`ndbd' process is run on a single physical machine.

*Note*:

We may support multiple data nodes per host in a future MySQL release,
following additional testing. However, in current versions of MySQL
Cluster, such configurations can be considered experimental only.

Multiple network addresses

Multiple network addresses per data node are not supported. Use of
these is liable to cause problems: In the event of a data node failure,
an SQL node waits for confirmation that the data node went down but
never receives it because another route to that data node remains open.
This can effectively make the cluster inoperable.

*Note*:

It is possible to use multiple network hardware _interfaces_ (such as
Ethernet cards) for a single data node, but these must be bound to the
same address. This also means that it not possible to use more than one
`[tcp]' section per connection in the `config.ini' file. See *Note
mysql-cluster-tcp-definition::, for more information.


File: manual.info,  Node: mysql-cluster-limitations-resolved,  Prev: mysql-cluster-limitations-multiple-nodes,  Up: mysql-cluster-limitations

20.14.11 Previous MySQL Cluster Issues Resolved in MySQL 5.1
------------------------------------------------------------

A number of limitations and related issues existing in earlier versions
of MySQL Cluster have been resolved:

   * Variable-length column support

     The `NDBCLUSTER' storage engine now supports variable-length
     column types for in-memory tables.

     Previously, for example, any Cluster table having one or more
     `VARCHAR' fields which contained only relatively small values,
     much more memory and disk space were required when using the
     `NDBCLUSTER' storage engine than would have been the case for the
     same table and data using the `MyISAM' engine.  In other words, in
     the case of a `VARCHAR' column, such a column required the same
     amount of storage as a `CHAR' column of the same size. In MySQL
     5.1, this is no longer the case for in-memory tables, where
     storage requirements for variable-length column types such as
     `VARCHAR' and `BINARY' are comparable to those for these column
     types when used in `MyISAM' tables (see *Note
     storage-requirements::).

     *Important*:

     For MySQL Cluster Disk Data tables, the fixed-width limitation
     continues to apply. See *Note mysql-cluster-disk-data::.

   * Replication with MySQL Cluster

     It is now possible to use MySQL replication with Cluster
     databases. For details, see *Note mysql-cluster-replication::.

     Circular Replication

     Circular replication is supported for MySQL Cluster beginning with
     MySQL 5.1.18. See *Note mysql-cluster-replication-issues::.

   * `auto_increment_increment' and `auto_increment_offset'

     The `auto_increment_increment' and `auto_increment_offset' server
     system variables are supported for Cluster replication beginning
     with MySQL 5.1.20.

   * Database autodiscovery and online schema changes

     Autodiscovery of databases is now supported for multiple MySQL
     servers accessing the same MySQL Cluster, provided that a given
     `mysqld' is already running and is connected to the cluster at the
     time that the database is created on a different `mysqld'.

     What this means is that if a `mysqld' process first connects to
     the cluster after a database named DB_NAME has been created, you
     should issue a `CREATE SCHEMA DB_NAME' statement on the `new'
     MySQL server when it first accesses that MySQL Cluster. Once this
     has been done, the `new' `mysqld' should be able to detect any
     tables in that database tables without errors.

     This also means that online schema changes in `NDB' tables are now
     possible. That is, the result of operations such as `ALTER TABLE'
     and `CREATE INDEX' performed on one SQL node in the cluster are
     now visible to the cluster's other SQL nodes without any
     additional action being taken.

   * Backup and restore between architectures

     Beginning with MySQL 5.1.10, it is possible to perform a Cluster
     backup and restore between different architectures. Previously --
     for example -- you could not back up a cluster running on a
     big-endian platform and then restore from that backup to a cluster
     running on a little-endian system. (Bug#19255
     (http://bugs.mysql.com/19255))

   * Character set directory

     Beginning with MySQL 5.1.10, it is possible to install MySQL with
     Cluster support to a non-default location and change the search
     path for font description files using either the `--basedir' or
     `--character-sets-dir' options.  (Previously, `ndbd' in MySQL 5.1
     searched only the default path -- typically
     `/usr/local/mysql/share/mysql/charsets' -- for character sets.)

   * In MySQL 5.1, it is no longer necessary, when running multiple
     management servers, to restart all the cluster's data nodes to
     enable the management nodes to see one another.

   * Length of `CREATE TABLE' statements

     `CREATE TABLE' statements may be no more than 4096 characters in
     length. _This limitation affects MySQL 5.1.6, 5.1.7, and 5.1.8
     only_.  (See Bug#17813 (http://bugs.mysql.com/17813))

   * `IGNORE' and `REPLACE' functionality

     In MySQL 5.1.7 and earlier, `INSERT IGNORE', `UPDATE IGNORE', and
     `REPLACE' were supported only for primary keys, but not for unique
     keys. It was possible to work around this issue by removing the
     constraint, then dropping the unique index, performing any
     inserts, and then adding the unique index again.

     This limitation was removed for `INSERT IGNORE' and `REPLACE' in
     MySQL 5.1.8. (See Bug#17431 (http://bugs.mysql.com/17431).)

   * `AUTO_INCREMENT' columns

     In MySQL 5.1.10 and earlier versions, the maximum number of tables
     having `AUTO_INCREMENT' columns -- including those belonging to
     hidden primary keys -- was 2048.

     This limitation was lifted in MySQL 5.1.11.

   * Maximum number of cluster nodes

     Prior to MySQL Cluster NDB 6.1.1, the total maximum number of
     nodes in a MySQL Cluster was 63, including all SQL nodes (MySQL
     Servers), API nodes (applications accessing the cluster other than
     MySQL servers), data nodes, and management servers.

     Starting with MySQL Cluster NDB 6.1.1, up to 255 API nodes
     (including MySQL servers acting as cluster SQL nodes) are
     supported by a single cluster. The total number of data nodes and
     management nodes beginning with this version is 63, of which up to
     48 can be data nodes.

     *Note*:

     The limitation that a data node cannot have a node ID greater than
     49 continues to apply.

   * Recovery of memory from deleted rows

     Beginning with MySQL Cluster NDB 6.3.7, memory can be reclaimed
     from an `NDB' table for reuse with any `NDB' table by employing
     `OPTIMIZE TABLE', subject to the following limitations:

        * Only in-memory tables are supported; the `OPTIMIZE TABLE'
          statement still has no effect on MySQL Cluster Disk Data
          tables.

        * Only variable-length columns (such as those declared as
          `VARCHAR', `TEXT', or `BLOB') are supported.

          However, you can force columns defined using fixed-length
          data types (such as `CHAR') to be dynamic using the
          `ROW_FORMAT' or `COLUMN_FORMAT' option with a `CREATE TABLE'
          or `ALTER TABLE' statement.

          See *Note create-table::, and *Note alter-table::, for
          information on these options.

     You can regulate the effects of `OPTIMIZE' on performance by
     adjusting the value of the global system variable
     `ndb_optimization_delay', which sets the number of milliseconds to
     wait between batches of rows being processed by `OPTIMIZE'. The
     default value is 10 milliseconds. It is possible to set a lower
     value (to a minimum of `0'), but not recommended. The maximum is
     100000 milliseconds (that is, 100 seconds).


File: manual.info,  Node: mysql-cluster-roadmap,  Next: mysql-cluster-glossary,  Prev: mysql-cluster-limitations,  Up: mysql-cluster

20.15 MySQL Cluster Development Roadmap
=======================================

* Menu:

* mysql-cluster-changes-5-1::    Features Added in MySQL 5.1 Cluster
* mysql-cluster-changes-5-1-ndb-6-1::  Features Added in MySQL Cluster NDB 6.1
* mysql-cluster-changes-5-1-ndb-6-2::  Features Added in MySQL Cluster NDB 6.2
* mysql-cluster-changes-5-1-ndb-6-3::  Features Added in MySQL Cluster NDB 6.3

In this section, we discuss changes in the implementation of MySQL
Cluster in MySQL 5.1 and MySQL Cluster NDB as compared to MySQL 5.0.

There are a number of significant changes in the implementation of the
`NDBCLUSTER' storage engine in mainline MySQL 5.1 releases up to and
including MySQL 5.1.23 as compared to that in MySQL 5.0; MySQL Cluster
NDB makes further changes and improvements in MySQL Cluster in addition
to these. The changes and features most likely to be of interest are
shown in the following table:

*Note MySQL 5.1 (through 5.1.23):                                                                              
mysql-cluster-changes-5-1.                                                                                     
MySQL Cluster Replication                                                                                      
Disk Data storage                                                                                              
Variable-size columns                                                                                          
User-defined partitioning                                                                                      
Autodiscovery of table schema                                                                                  
changes                                                                                                        
Online adding and dropping of                                                                                  
indexes                                                                                                        
*Note MySQL Cluster NDB 6.1:                                                                                   
mysql-cluster-changes-5-1-ndb-6-1.                                                                             
Greater number of cluster nodes                                                                                
Disabling of arbitration                                                                                       
Additional `DUMP' commands                                                                                     
Faster Disk Data backups                                                                                       
Batched slave updates                                                                                          
*Note MySQL Cluster NDB 6.2:                                                                                   
mysql-cluster-changes-5-1-ndb-6-2.                                                                             
Improved backup status reporting                                                                               
(`BackupReportFrequency', `REPORT                                                                              
BackupStatus')                                                                                                 
Multiple connections per SQL node                                                                              
Data access with `NdbRecord' (NDB                                                                              
API)                                                                                                           
`REPORT MemoryUsage' command                                                                                   
Memory allocation improvements                                                                                 
Management client connection control                                                                           
Micro-GCPs                                                                                                     
Online `ADD COLUMN'; improved                                                                                  
online index creation                                                                                          
*Note MySQL Cluster NDB 6.3:                                                                                   
mysql-cluster-changes-5-1-ndb-6-3.                                                                             
Conflict detection and resolution                                                                              
for multi-master replication                                                                                   
Compressed backups and local                                                                                   
checkpoints                                                                                                    
Support for `OPTIMIZE TABLE'                                                                                   
Parallel data node recovery                                                                                    
Enhanced transaction coordinator                                                                               
selection                                                                                                      
Improved SQL statement performance                                                                             
metrics                                                                                                        
Transaction batching                                                                                           
`ndb_restore' attribute promotion                                                                              
Support for `epoll' (Linux only)                                                                               
Distribution awareness                                                                                         
`NDB' thread locks; realtime                                                                                   
extensions for multiple CPUs                                                                                   


File: manual.info,  Node: mysql-cluster-changes-5-1,  Next: mysql-cluster-changes-5-1-ndb-6-1,  Prev: mysql-cluster-roadmap,  Up: mysql-cluster-roadmap

20.15.1 Features Added in MySQL 5.1 Cluster
-------------------------------------------

A number of new features for MySQL Cluster have been implemented in
MySQL 5.1 through MySQL 5.1.23, when support for MySQL Cluster was
moved to MySQL Cluster NDB. All of the features in the following list
are also available in all MySQL Cluster NDB (6.1 and later) releases.

   * Integration of MySQL Cluster into MySQL Replication

     MySQL Cluster Replication makes it possible to replicate from one
     MySQL Cluster to another. Updates on any SQL node (MySQL server)
     in the cluster acting as the master are replicated to the slave
     cluster; the state of the slave side remains consistent with the
     cluster acting as the master.  This is sometimes referred to as
     _asynchronous replication_ between clusters, providing _geographic
     redundancy_. It is also possible to replicate from a MySQL Cluster
     acting as the master to a standalone MySQL server acting as the
     slave, or from a standalone MySQL master server to to a slave
     cluster; in either of these cases, the standalone MySQL server
     uses a storage engine other than `NDBCLUSTER'.  Multi-master
     replication setups such as circular replication are also supported.

     See *Note mysql-cluster-replication::.

   * Support for storage of rows on disk

     Storage of `NDBCLUSTER' table data on disk is now supported.
     Indexed columns, including the primary key hash index, must still
     be stored in RAM; however, all other columns can be stored on disk.

     See *Note mysql-cluster-disk-data::.

   * Variable-size columns

     In MySQL 5.0, an `NDBCLUSTER' table column defined as
     `VARCHAR(255)' used 260 bytes of storage independent of what was
     stored in any particular record. In MySQL 5.1 Cluster tables, only
     the portion of the column actually taken up by the record is
     stored. This makes possible a significant reduction in space
     requirements for such columns as compared to previous release
     series -- by a factor of up to 5 in many cases.

   * User-defined partitioning

     Users can define partitions based on columns that are part of the
     primary key. It is possible to partition `NDB' tables based on
     `KEY' and `LINEAR KEY' schemes. This feature is also available for
     many other MySQL storage engines, which support additional
     partitioning types that are not available with `NDBCLUSTER' tables.

     For additional general information about user-defined partitioning
     in MySQL 5.1, see *Note partitioning::. Specifics of partitioning
     types are discussed in *Note partitioning-types::.

     The MySQL Server can also determine whether it is possible to
     `prune away' some of the partitions from the `WHERE' clause, which
     can greatly speed up some queries. See *Note
     partitioning-pruning::, for information about designing tables and
     queries to take advantage of partition pruning.

   * Autodiscovery of table schema changes

     In MySQL 5.0, it was necessary to issue a `FLUSH TABLES' statement
     or a `dummy' `SELECT' in order for new `NDBCLUSTER' tables or
     changes made to schemas of existing `NDBCLUSTER' tables on one SQL
     node to be visible on the cluster's other SQL nodes. In MySQL 5.1,
     this is no longer necessary; new Cluster tables and changes in the
     definitions of existing `NDBCLUSTER' tables made on one SQL node
     are immediately visible to all SQL nodes connected to the cluster.

     *Note*:

     When creating a new database, it is still necessary in MySQL 5.1
     to issue a `CREATE DATABASE' or `CREATE SCHEMA' statement on each
     SQL node in the cluster.

   * Distribution awareness (NDB API)

     _Distribution awareness_ is a mechanism by which the best data
     node is automatically selected to be queried for information.
     (Conceptually, it is similar in some ways to partition pruning (see
     *Note partitioning-pruning::). To take advantage of distribution
     awareness, you should do the following:

       1. Determine which table column is most likely to be used for
          finding matching records.

       2. Make this column part of the table's primary key.

       3. Explicitly partition the table by `KEY', using this column as
          the table' partitioning key.

     Following these steps causes records with the same value for the
     partitioning column to be stored on the same partition (that is,
     in the same node group). When reading data, transactions are begun
     on the data node actually having the desired rows instead of this
     node being determined by the usual round-robin mechanism.

     *Important*:

     In order to see a measureable impact on performance, the cluster
     must have at least four data nodes, since, with only two data
     nodes, both data nodes have exactly the same data.

     Using distribution awareness can yield performance increase of as
     great as 45% when using four data nodes, and possibly more when
     using a greater number of data nodes.

     *Note*:

     In mainline MySQL 5.1 releases, distribution awareness was
     supported only when using the NDB API; support was added for SQL
     and API nodes in MySQL Cluster NDB 6.3 (see *Note
     mysql-cluster-changes-5-1-ndb-6-3::, which includes an example
     showing how to create a table in order to take advantage of
     distribution awareness).

See *Note mysql-cluster-limitations-resolved::, for more information.


File: manual.info,  Node: mysql-cluster-changes-5-1-ndb-6-1,  Next: mysql-cluster-changes-5-1-ndb-6-2,  Prev: mysql-cluster-changes-5-1,  Up: mysql-cluster-roadmap

20.15.2 Features Added in MySQL Cluster NDB 6.1
-----------------------------------------------

The following list provides an overview of significant feature
additions and changes made in MySQL Cluster NDB 6.1. All of the changes
in this list are also available in MySQL Cluster NDB 6.2 and 6.3
releases. For detailed information about all changes made in MySQL
Cluster NDB 6.1, see *Note mysql-cluster-news-6-1::.

   * Increased number of cluster nodes

     The maximum number of all nodes in a MySQL Cluster has been
     increased to 255. For more information, see *Note
     mysql-cluster-limitations-multiple-nodes::.

   * Disabling arbitration

     It is now possible to disable arbitration by setting
     `ArbitrationRank=0' on all cluster management and SQL nodes. For
     more information, see `Defining the Management Server:
     `ArbitrationRank'' and `Defining SQL and Other API Nodes:
     `ArbitrationRank''.

   * Additional `DUMP' commands

     New management client `DUMP' commands provide help with tracking
     transactions, scan operations, and locks. See *Note
     mysql-cluster-mgm-client-commands::, and `DUMP' Commands
     (http://dev.mysql.com/doc/ndbapi/en/ndb-internals-dump-commands.html),
     for more information.

   * Faster Disk Data backups

     Improvements in backups of Disk Data tables can yield a 10 to 15%
     increase in backup speed of Disk Data tables.

   * Batched slave updates

     Batching of updates on cluster replication slaves, enabled using
     the `--slave-allow-batching' option for `mysqld', increases
     replication efficiency. For more information, see *Note
     mysql-cluster-replication-starting::.


File: manual.info,  Node: mysql-cluster-changes-5-1-ndb-6-2,  Next: mysql-cluster-changes-5-1-ndb-6-3,  Prev: mysql-cluster-changes-5-1-ndb-6-1,  Up: mysql-cluster-roadmap

20.15.3 Features Added in MySQL Cluster NDB 6.2
-----------------------------------------------

The following list provides an overview of significant feature
additions and changes made in MySQL Cluster NDB 6.2. All of the changes
in this list are also available in MySQL Cluster NDB 6.3 .  For more
detailed information about all feature changes and bugfixes made in
MySQL Cluster NDB 6.2, see *Note mysql-cluster-news-6-2::.

   * Enhanced backup status reporting

     Backup status reporting has been improved, aided in part by the
     introduction of a `BackupReportFrequency' configuration parameter;
     see `Defining Data Nodes: `BackupReportFrequency'', for more
     information.

   * Multiple cluster connections per SQL node

     A single MySQL server acting as a MySQL Cluster SQL node can
     employ multiple connections to the cluster using the
     `--ndb-cluster-connection-pool' startup option for `mysqld'. This
     option is described in `MySQL Cluster-Related Command Options for
     `mysqld': `--ndb-cluster-connection-pool' option'.

   * New data access interface

     The `NdbRecord' interface provides a new and simplified data
     handler for use in NDB API applications. See The `NdbRecord'
     Interface
     (http://dev.mysql.com/doc/ndbapi/en/interface-ndbrecord.html), for
     more information.

   * New reporting commands

     The new management client `REPORT BackupStatus' and `REPORT
     MemoryUsage' commands provide better access to information about
     the status of MySQL Cluster backups and how much memory is being
     used by MySQL Cluster for data and index storage. See *Note
     mysql-cluster-mgm-client-commands::, for more information about
     the `REPORT' commands. In addition, in-progress status reporting is
     provided by the `ndb_restore' utility; see *Note
     mysql-cluster-restore::.

   * Improved memory allocation and configuration

     Memory is now allocated by the `NDB' kernel to tables on a
     page-by-page basis, which significantly reduces the memory
     overhead required for maintaining `NDBCLUSTER' tables. In
     addition, the `MaxAllocate' configuration parameter now makes it
     possible to set the maximum size of the allocation unit used for
     table memory; for more information about this configuration
     parameter, see `Defining Data Nodes: `MaxAllocate''.

   * Choice of fixed-width or variable-width columns

     You can control whether fixed-width or variable-width storage is
     used for a given column of an `NDB' table by employing of the
     `COLUMN_FORMAT' specifier as part of the column's definition in a
     `CREATE TABLE' or `ALTER TABLE' statement. In addition, the
     ability to control whether a given column of an `NDB' table is
     stored in memory or on disk, using the `STORAGE' specifier as part
     of the column's definition in a `CREATE TABLE' or `ALTER TABLE'
     statement. For more information, see *Note create-table::, and
     *Note alter-table::.

   * Controlling management client connections

     The `--bind-address' cluster management server startup option
     makes it possible to restrict management client connections to
     `ndb_mgmd' to a single host (IP address or hostname) and port,
     which can make MySQL Cluster management operations more secure.
     For more information about this option, see *Note
     mysql-cluster-ndb-mgmd-command-options::.

   * Micro-GCPs

     Due to a change in the protocol for handling of global checkpoints
     (GCPs handled in this manner sometimes being referred to as
     `micro-GCPs'), it is now possible to control how often the GCI
     number is updated, and how often global checkpoints are written to
     disk, using the `TimeBetweenEpochs' configuration parameter. This
     improves the reliability and performance of MySQL Cluster
     Replication. For more information, see `Defining Data Nodes:
     `TimeBetweenEpochs'' and `Defining Data Nodes:
     `TimeBetweenEpochsTimeout''.

   * Core online schema change support

     Support for the online `ALTER TABLE' operations `ADD COLUMN', `ADD
     INDEX', and `DROP INDEX' is available. When the `ONLINE' keyword is
     used, the `ALTER TABLE' is non-copying, which means that indexes
     do not have to be re-created, which provides these benefits:

        * Single user mode is no longer required for `ALTER TABLE'
          operations that can be performed online.

        * Transactions can continue during `ALTER TABLE' operations
          that can be performed online.

        * Tables being altered online are not locked.

     Online `CREATE INDEX' and `DROP INDEX' statements are also
     supported. Online changes can be suppressed using the `OFFLINE'
     key word. See *Note alter-table::, *Note create-index::, and *Note
     drop-index::, for more detailed information.

   * `mysql.ndb_binlog_index' improvements

     More information has been added to the `mysql.ndb_binlog_index'
     table so that it is possible to determine which originating epochs
     have been applied inside an epoch. This is particularly useful for
     3-way replication. See *Note mysql-cluster-replication-schema::,
     for more information.

   * Epoch lag control

     The `MaxBufferedEpochs' data node configuration parameter provides
     a means to control the maximum number of unprocessed epochs by
     which a subscribing node can lag. Subscribers which exceed this
     number are disconnected and forced to reconnect. For a discussion
     of this configuration parameter, see `Defining Data Nodes:
     `MaxBufferedEpochs''.


File: manual.info,  Node: mysql-cluster-changes-5-1-ndb-6-3,  Prev: mysql-cluster-changes-5-1-ndb-6-2,  Up: mysql-cluster-roadmap

20.15.4 Features Added in MySQL Cluster NDB 6.3
-----------------------------------------------

The following list provides an overview of significant feature
additions and changes first made in MySQL Cluster NDB 6.3. For more
detailed information about all feature changes and bugfixes made in
MySQL Cluster NDB 6.3, see *Note mysql-cluster-news-6-3::.

   * Conflict detection and resolution

     It is now possible to detect and resolve conflicts that arise in
     multi-master replication scenarios, such as circular replication,
     when different masters may try to update the same row on the slave
     with different data. Both `greatest timestamp wins' and `same
     timestamp wins' scenarios are supported. For more information, see
     *Note mysql-cluster-replication-conflict-resolution::.

   * Recovery of `one master, many slaves' replication setups

     Recovery of multi-way replication setups (`one master, many
     slaves') is now supported via the `--ndb-log-orig' server option
     and changes in the `mysql.ndb_binlog_index' table.  See *Note
     mysql-cluster-replication-schema::, for more information.

   * Enhanced selection options for transaction coordinator

     New values and behaviors are introduced for
     `--ndb_optimized_node_selection' allowing for greater flexibility
     when an SQL node chooses a transaction coordinator. See `MySQL
     Cluster System Variables: `ndb_optimized_node_selection'', for
     more information.

   * Replication heartbeats

     Replication heartbeats facilitate the task of monitoring and
     detecting failures in master-slave connections in real time. This
     feature is implemented via a new `MASTER_HEARTBEAT_PERIOD = VALUE'
     clause for the `CHANGE MASTER TO' statement and the addition of
     two status variables `Slave_heartbeat_period' and
     `Slave_received_heartbeats'. For more information, see *Note
     change-master-to::.

   * `NDB' thread locks

     It is possible to lock `NDB' execution threads and maintenance
     threads (such as filesystem and other operating system threads) to
     specific CPUs on multiprocessor data node hosts, and to leverage
     real-time scheduling.

   * Improved performance of updates using primary keys or unique keys

     The number of unnecessary reads when performing a primary key or
     unique key update has been greatly reduced. Since it is seldom
     necessary to read a record prior to an update, this can yield a
     considerable improvement in performance. In addition, primary key
     columns are no longer written to when not needed during update
     operations.

   * Batching improvements

     Support of batched `DELETE' and `UPDATE' operations has been
     significantly improved. Batching of `UPDATE WHERE...' and multiple
     `DELETE' operations is also now implemented.

   * Improved SQL statement performance metrics

     The `Ndb_execute_count' system status variable measures the number
     of round trips made by SQL statements to the `NDB' kernel,
     providing an improved metric for determining efficiency with which
     statements are excuted. For more information, see `MySQL Cluster
     Status Variables: `Ndb_execute_count''.

   * Compressed LCPs and backups

     Compressed local checkpoints and backups can save 50% or more of
     the disk space used by uncompressed LCPs and backups. These can be
     enabled using the two new data node configuration parameters
     `CompressedLCP' and `CompressedBackup', respectively. See `MySQL
     Cluster Status Variables: `CompressedBackup'', and `MySQL Cluster
     Status Variables: `CompressedLCP'', for more information about
     these parameters.

   * `OPTIMIZE TABLE' support with `NDBCLUSTER' tables

     `OPTIMIZE TABLE' is supported for dynamic columns of in-memory
     `NDB' tables. In such cases, it is no longer necessary to drop (and
     possibly to re-create) a table, or to perform a rolling restart,
     in order to recover memory from deleted rows for general re-use by
     Cluster. The performance of `OPTIMIZE' on Cluster tables can be
     tuned by adjusting the value of the `ndb_optimization_delay'
     system variable, which controls the number of milliseconds to wait
     between processing batches of rows by `OPTIMIZE TABLE'. In
     addition, `OPTIMIZE TABLE' on an `NDBCLUSTER' table can be
     interrupted by, for example, killing the SQL thread performing the
     `OPTIMIZE' operation.

   * Batching of transactions

     It is possible to cause statements occurring within the same
     transaction to be run as a batch by setting the session variable
     `transaction_allow_batching' to `1' or `ON'. To use this feature,
     `AUTOCOMMIT' must be set to `0' or `OFF'. Batch sizes can be
     controlled using the `--ndb-batch-size' option for `mysqld'. For
     more information, see *Note mysql-cluster-mysqld-command-options::,
     and *Note mysql-cluster-system-variables::.

   * Attribute promotion with `ndb_restore'

     It is possible using `ndb_restore' to restore data reliably from a
     column of a given type to a column that uses a `larger' type. This
     is sometimes referred to as _attribute promotion_. For example,
     MySQL Cluster backup data that originated in a `SMALLINT' column
     can be restored to a `MEDIUMINT', `INT', or `BIGINT' column. See
     *Note mysql-cluster-restore::, for more information.

   * Parallel data node recovery

     Recovery of multiple data nodes can now be done in parallel,
     rather than sequentially. In other words, several data nodes can
     be restored concurrently, which can often result in much faster
     recovery times than when they are restored one at a time.

   * Increased local checkpoint efficiency

     Only 2 local checkpoints are stored, rather than 3, lowering disk
     space requirements and the size and number of redo log files.

   * `NDBCLUSTER' table persistence control

     Persistence of `NDB' tables can be controlled using the session
     variables `ndb_table_temporary' and `ndb_table_no_logging'.
     `ndb_table_no_logging' causes `NDB' tables not to be checkpointed
     to disk; `ndb_table_temporary' does the same, and in addition, no
     schema files are created. See *Note mysql-cluster-option-tables::.

   * Epoll support (_Linux only_)

     _Epoll_ is an improved method for handling file descriptors, which
     is more efficient than scanning to determine whether a file
     descriptor has data to be read. (The term _epoll_ is specific to
     Linux and equivalent functionality is known by other names on
     other platforms such as Solaris and FreeBSD.) Currently, MySQL
     Cluster supports this functionality on Linux only.

   * Distribution awareness (SQL nodes)

     In MySQL Cluster NDB 6.3, SQL nodes can take advantage of
     distribution awareness. Here we provide a brief example showing
     how to design a table to make a given class of queries
     distrubtion-aware. Suppose an `NDBCLUSTER' table `t1' has the
     following schema:

          CREATE TABLE t1 (
              userid INT NOT NULL,
              serviceid INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
              data VARCHAR(255)
          )   ENGINE=NDBCLUSTER;

     Suppose further that most of the queries to be used in our
     application test values of the `userid' column of this table. The
     form of such a query looks something like this:

          SELECT COLUMNS FROM t1
              WHERE userid RELATION VALUE;

     In this query, RELATION represents some relational operator, such
     as `=', `<', `>', and so on. Queries using `IN' and a list of
     values can also be used:

          SELECT COLUMNS FROM t1
              WHERE userid IN VALUE_LIST;

     In order to make use of distribution awareness, we need to make
     the `userid' column part of the table's primary key, then
     explicitly partition the table with this column being used as the
     partitioning key.  (Recall that for a partitioned table having one
     or more unique keys, all columns of the table's partitioning key
     must also be part of all of the unique keys -- for more
     information and examples, see *Note
     partitioning-limitations-partitioning-keys-unique-keys::.)  In
     other words, the table schema should be equivalent to the
     following `CREATE TABLE' statement:

          CREATE TABLE t1 (
              userid INT NOT NULL,
              serviceid INT NOT NULL AUTO_INCREMENT,
              data VARCHAR(255),
              PRIMARY KEY p (userid,serviceid)
          )   ENGINE=NDBCLUSTER
              PARTITION BY KEY(userid);

     When the table is partitioned in this way, all rows having the
     same `userid' value are found on the same node group, and the
     MySQL Server can immediately select the optimal node to use as the
     transaction coordinator.

   * Realtime extensions for multiple CPUs

     When running MySQL Cluster data nodes on hosts with multiple
     processors, the realtime extensions make it possible to give
     priority to the data node process and control on which CPU cores
     it should operate. This can be done using the data node
     configuration parameters `RealtimeScheduler',
     `SchedulerExecutionTimer' and `SchedulerSpinTimer'. Doing so
     properly can significantly lower response times and make them much
     more predictable response. For more information about using these
     parameters, see Defining Data Nodes: Realtime Performance
     Parameters


File: manual.info,  Node: mysql-cluster-glossary,  Next: mysql-cluster-news,  Prev: mysql-cluster-roadmap,  Up: mysql-cluster

20.16 MySQL Cluster Glossary
============================

The following terms are useful to an understanding of MySQL Cluster or
have specialized meanings when used in relation to it.

   * Cluster

     In its generic sense, a cluster is a set of computers functioning
     as a unit and working together to accomplish a single task.

     `NDBCLUSTER'

     This is the storage engine used in MySQL to implement data
     storage, retrieval, and management distributed among several
     computers.

     MySQL Cluster

     This refers to a group of computers working together using the
     `NDB' storage engine to support a distributed MySQL database in a
     _shared-nothing architecture_ using _in-memory storage_.

   * Configuration files

     Text files containing directives and information regarding the
     cluster, its hosts, and its nodes. These are read by the cluster's
     management nodes when the cluster is started. See *Note
     mysql-cluster-config-file::, for details.

   * Backup

     A complete copy of all cluster data, transactions and logs, saved
     to disk or other long-term storage.

   * Restore

     Returning the cluster to a previous state, as stored in a backup.

   * Checkpoint

     Generally speaking, when data is saved to disk, it is said that a
     checkpoint has been reached. More specific to Cluster, it is a
     point in time where all committed transactions are stored on disk.
     With regard to the `NDB' storage engine, there are two types of
     checkpoints which work together to ensure that a consistent view
     of the cluster's data is maintained:

        * Local Checkpoint (LCP)

          This is a checkpoint that is specific to a single node;
          however, LCP's take place for all nodes in the cluster more
          or less concurrently. An LCP involves saving all of a node's
          data to disk, and so usually occurs every few minutes. The
          precise interval varies, and depends upon the amount of data
          stored by the node, the level of cluster activity, and other
          factors.

        * Global Checkpoint (GCP)

          A GCP occurs every few seconds, when transactions for all
          nodes are synchronized and the redo-log is flushed to disk.

   * Cluster host

     A computer making up part of a MySQL Cluster. A cluster has both a
     _physical_ structure and a _logical_ structure. Physically, the
     cluster consists of a number of computers, known as _cluster
     hosts_ (or more simply as _hosts_. See also *Node* and *Node
     group* below.

   * Node

     This refers to a logical or functional unit of MySQL Cluster, and
     is sometimes also referred to as a _cluster node_. In the context
     of MySQL Cluster, we use the term `node' to indicate a _process_
     rather than a physical component of the cluster. There are three
     node types required to implement a working MySQL Cluster:

        * Management nodes

          Manages the other nodes within the MySQL Cluster. It provides
          configuration data to the other nodes; starts and stops
          nodes; handles network partitioning; creates backups and
          restores from them, and so forth.

        * SQL nodes

          Instances of MySQL Server which serve as front ends to data
          kept in the cluster's *data nodes*. Clients desiring to
          store, retrieve, or update data can access an SQL node just
          as they would any other MySQL Server, employing the usual
          MySQL authentication methods and APIs; the underlying
          distribution of data between node groups is transparent to
          users and applications. SQL nodes access the cluster's
          databases as a whole without regard to the data's
          distribution across different data nodes or cluster hosts.

        * Data nodes

          These nodes store the actual data. Table data fragments are
          stored in a set of node groups; each node group stores a
          different subset of the table data. Each of the nodes making
          up a node group stores a replica of the fragment for which
          that node group is responsible. Currently, a single cluster
          can support up to 48 data nodes total.

     It is possible for more than one node to co-exist on a single
     machine. (In fact, it is even possible to set up a complete
     cluster on one machine, although one would almost certainly _not_
     want to do this in a production environment.) It may be helpful to
     remember that, when working with MySQL Cluster, the term _host_
     refers to a physical component of the cluster whereas a _node_ is
     a logical or functional component (that is, a process).

     Note Regarding Terms

     In older versions of the MySQL Cluster documentation, data nodes
     were sometimes referred to as `database nodes'. The term `storage
     nodes' has also been used. In addition, SQL nodes were sometimes
     known as `client nodes'. This older terminology has been
     deprecated to minimize confusion, and for this reason should be
     avoided. They are also often referred to as `API nodes' -- an SQL
     node is actually an API node that provides an SQL interface to the
     cluster.

   * Node group

     A set of data nodes. All data nodes in a node group contain the
     same data (fragments), and all nodes in a single group should
     reside on different hosts. It is possible to control which nodes
     belong to which node groups.

     For more information, see *Note mysql-cluster-nodes-groups::.

   * Node failure

     MySQL Cluster is not solely dependent upon the functioning of any
     single node making up the cluster; the cluster can continue to run
     if one or more nodes fail. The precise number of node failures
     that a given cluster can tolerate depends upon the number of nodes
     and the cluster's configuration.

   * Node restart

     The process of restarting a failed cluster node.

   * Initial node restart

     The process of starting a cluster node with its filesystem
     removed. This is sometimes used in the course of software upgrades
     and in other special circumstances.

   * System crash (or system failure)

     This can occur when so many cluster nodes have failed that the
     cluster's state can no longer be guaranteed.

   * System restart

     The process of restarting the cluster and reinitializing its state
     from disk logs and checkpoints. This is required after either a
     planned or an unplanned shutdown of the cluster.

   * Fragment

     A portion of a database table; in the `NDB' storage engine, a
     table is broken up into and stored as a number of fragments. A
     fragment is sometimes also called a `partition'; however,
     `fragment' is the preferred term. Tables are fragmented in MySQL
     Cluster in order to facilitate load balancing between machines and
     nodes.

   * Replica

     Under the `NDB' storage engine, each table fragment has number of
     replicas stored on other data nodes in order to provide
     redundancy. Currently, there may be up four replicas per fragment.

   * Transporter

     A protocol providing data transfer between nodes. MySQL Cluster
     currently supports four different types of transporter connections:

        * TCP/IP

          This is, of course, the familiar network protocol that
          underlies HTTP, FTP (and so on) on the Internet. TCP/IP can
          be used for both local and remote connections.

        * SCI

          *S*calable *C*oherent *I*nterface is a high-speed protocol
          used in building multiprocessor systems and
          parallel-processing applications. Use of SCI with MySQL
          Cluster requires specialized hardware, as discussed in *Note
          mysql-cluster-sci-sockets::. For a basic introduction to SCI,
          see this essay at dolphinics.com
          (http://www.dolphinics.com/corporate/scitech.html).

        * SHM

          Unix-style *sh*ared *m*emory segments. Where supported, SHM
          is used automatically to connect nodes running on the same
          host. The Unix man page for `shmop(2)'
          (http://www.scit.wlv.ac.uk/cgi-bin/mansec?2+shmop) is a good
          place to begin obtaining additional information about this
          topic.

     *Note*:

     The cluster transporter is internal to the cluster.  Applications
     using MySQL Cluster communicate with SQL nodes just as they do
     with any other version of MySQL Server (via TCP/IP, or through the
     use of Unix socket files or Windows named pipes). Queries can be
     sent and results retrieved using the standard MySQL client APIs.

   * `NDB'

     This stands for *N*etwork *D*ata*b*ase, and refers to the storage
     engine used to enable MySQL Cluster.  The `NDB' storage engine
     supports all the usual MySQL data types and SQL statements, and is
     ACID-compliant. This engine also provides full support for
     transactions (commits and rollbacks).

   * Shared-nothing architecture

     The ideal architecture for a MySQL Cluster. In a true
     shared-nothing setup, each node runs on a separate host. The
     advantage such an arrangement is that there no single host or node
     can act as single point of failure or as a performance bottle neck
     for the system as a whole.

   * In-memory storage

     All data stored in each data node is kept in memory on the node's
     host computer. For each data node in the cluster, you must have
     available an amount of RAM equal to the size of the database times
     the number of replicas, divided by the number of data nodes. Thus,
     if the database takes up 1GB of memory, and you want to set up the
     cluster with four replicas and eight data nodes, a minimum of
     500MB memory will be required per node. Note that this is in
     addition to any requirements for the operating system and any
     other applications that might be running on the host.

     In MySQL 5.1, it is also possible to create _Disk Data_ tables
     where non-indexed columns are stored on disk, thus reducing the
     memory footprint required by the cluster. Note that indexes and
     indexed column data are still stored in RAM. See *Note
     mysql-cluster-disk-data::.

   * Table

     As is usual in the context of a relational database, the term
     `table' denotes a set of identically structured records. In MySQL
     Cluster, a database table is stored in a data node as a set of
     fragments, each of which is replicated on additional data nodes.
     The set of data nodes replicating the same fragment or set of
     fragments is referred to as a _node group_.

   * Cluster programs

     These are command-line programs used in running, configuring, and
     administering MySQL Cluster. They include both server daemons:

        * `ndbd':

          The data node daemon (runs a data node process)

        * `ndb_mgmd':

          The management server daemon (runs a management server
          process)

     and client programs:

        * `ndb_mgm':

          The management client (provides an interface for executing
          management commands)

        * `ndb_waiter':

          Used to verify status of all nodes in a cluster

        * `ndb_restore':

          Restores cluster data from backup

     For more about these programs and their uses, see *Note
     mysql-cluster-process-management::.

   * Event log

     MySQL Cluster logs events by category (startup, shutdown, errors,
     checkpoints, and so on), priority, and severity. A complete
     listing of all reportable events may be found in *Note
     mysql-cluster-event-reports::. Event logs are of two types:

        * Cluster log

          Keeps a record of all desired reportable events for the
          cluster as a whole.

        * Node log

          A separate log which is also kept for each individual node.

     Under normal circumstances, it is necessary and sufficient to keep
     and examine only the cluster log. The node logs need be consulted
     only for application development and debugging purposes.

   * Angel process

     When a data node is started, `ndbd' actually starts two processes.
     One of these is known as the `angel' process; its purpose is to
     check to make sure that the main `ndbd' process continues to run,
     and to restart the main process if it should stop for any reason.

   * Watchdog thread

     Each `ndbd' process has an internal _watchdog thread_ which
     monitors the main worker thread, ensuring forward progress and a
     timely response to cluster protocols such as the cluster
     heartbeat. If the `ndbd' process is not being woken up promptly by
     the operating system when its sleep time expires, `INFO' and
     `WARNING' events, which are identifiable because they contain
     `Watchdog:...', are written to the cluster log.  Such messages are
     usually a symptom of an overloaded system; you should see what
     else is running on the system, and whether the ndbd `process' is
     being swapped out to disk. If `ndbd' cannot wake up regularly then
     it cannot respond to heartbeat messages on time, and other nodes
     eventually consider it `dead' due to the missed heartbeats,
     causing it to be excluded from the cluster.


File: manual.info,  Node: mysql-cluster-news,  Prev: mysql-cluster-glossary,  Up: mysql-cluster

20.17 Changes in MySQL Cluster 6.x
==================================

* Menu:

* mysql-cluster-news-6-3::       Changes in MySQL Cluster NDB 6.3
* mysql-cluster-news-6-2::       Changes in MySQL Cluster NDB 6.2
* mysql-cluster-news-6-1::       Changes in MySQL Cluster NDB 6.1

This section contains changelog information for MySQL Cluster that use
version 6.1, 6.2, and 6.3 of the `NDBCLUSTER' storage engine.

Each MySQL Cluster release is based on a mainline MySQL 5.1 release and
a particular version of the `NDBCLUSTER' storage engine, as shown in
the version string returned by executing `SELECT VERSION()' in the
`mysql' client, or by executing the `ndb_mgm' client `SHOW' or `STATUS'
command; for more information, see *Note mysql-cluster::.

For general information about features added in MySQL Cluster, see
*Note mysql-cluster-roadmap::. For a complete list of all bugfixes and
feature changes in MySQL Cluster, please refer to the changelog section
for each individual MySQL Cluster release.

An overview of features added in MySQL 5.1 not specific to MySQL
Cluster can be found here: *Note mysql-nutshell::. For a complete list
of all bugfixes and features changes made in MySQL 5.1 that are not
specific to MySQL Cluster, see *Note news-5-1-x::.


File: manual.info,  Node: mysql-cluster-news-6-3,  Next: mysql-cluster-news-6-2,  Prev: mysql-cluster-news,  Up: mysql-cluster-news

20.17.1 Changes in MySQL Cluster NDB 6.3
----------------------------------------

* Menu:

* mysql-cluster-news-5-1-24-ndb-6-3-16::  Changes in MySQL Cluster NDB 6.3.16 (5.1.24-ndb-6.3.16) (27 June 2008)
* mysql-cluster-news-5-1-24-ndb-6-3-15::  Changes in MySQL Cluster NDB 6.3.15 (5.1.24-ndb-6.3.15) (30 May 2008)
* mysql-cluster-news-5-1-24-ndb-6-3-14::  Changes in MySQL Cluster NDB 6.3.14 (5.1.24-ndb-6.3.14) (11 May 2008)
* mysql-cluster-news-5-1-24-ndb-6-3-13::  Changes in MySQL Cluster NDB 6.3.13 (5.1.24-ndb-6.3.13) (10 April 2008)
* mysql-cluster-news-5-1-23-ndb-6-3-12::  Changes in MySQL Cluster NDB 6.3.12 (5.1.23-ndb-6.3.12) (05 April 2008)
* mysql-cluster-news-5-1-23-ndb-6-3-11::  Changes in MySQL Cluster NDB 6.3.11 (5.1.23-ndb-6.3.11) (28 March 2008)
* mysql-cluster-news-5-1-23-ndb-6-3-10::  Changes in MySQL Cluster NDB 6.3.10 (5.1.23-ndb-6.3.10) (17 February 2008)
* mysql-cluster-news-5-1-23-ndb-6-3-9::  Changes in MySQL Cluster NDB 6.3.9 (5.1.23-ndb-6.3.9) (12 February 2008)
* mysql-cluster-news-5-1-23-ndb-6-3-8::  Changes in MySQL Cluster NDB 6.3.8 (5.1.23-ndb-6.3.8) (29 January 2008)
* mysql-cluster-news-5-1-23-ndb-6-3-7::  Changes in MySQL Cluster NDB 6.3.7 (5.1.23-ndb-6.3.7) (19 December 2007)
* mysql-cluster-news-5-1-22-ndb-6-3-6::  Changes in MySQL Cluster NDB 6.3.6 (5.1.22-ndb-6.3.6) (08 November 2007)
* mysql-cluster-news-5-1-22-ndb-6-3-5::  Changes in MySQL Cluster NDB 6.3.5 (5.1.22-ndb-6.3.5) (17 October 2007)
* mysql-cluster-news-5-1-22-ndb-6-3-4::  Changes in MySQL Cluster NDB 6.3.4 (5.1.22-ndb-6.3.4) (15 October 2007)
* mysql-cluster-news-5-1-22-ndb-6-3-3::  Changes in MySQL Cluster NDB 6.3.3 (5.1.22-ndb-6.3.3) (20 September 2007)
* mysql-cluster-news-5-1-22-ndb-6-3-2::  Changes in MySQL Cluster NDB 6.3.2 (5.1.22-ndb-6.3.2) (07 September 2007)
* mysql-cluster-news-5-1-19-ndb-6-3-1::  Changes in MySQL Cluster NDB 6.3.1 (5.1.19-ndb-6.3.1) (04 July 2007)
* mysql-cluster-news-5-1-19-ndb-6-3-0::  Changes in MySQL Cluster NDB 6.3.0 (5.1.19-ndb-6.3.0) (02 July 2007)

This section contains change history information for MySQL Cluster
releases based on version 6.3 of the `NDBCLUSTER' storage engine.

For an overview of new features added in MySQL Cluster NDB 6.3, see
*Note mysql-cluster-changes-5-1-ndb-6-3::.


File: manual.info,  Node: mysql-cluster-news-5-1-24-ndb-6-3-16,  Next: mysql-cluster-news-5-1-24-ndb-6-3-15,  Prev: mysql-cluster-news-6-3,  Up: mysql-cluster-news-6-3

20.17.1.1 Changes in MySQL Cluster NDB 6.3.16 (5.1.24-ndb-6.3.16) (27 June 2008)
................................................................................

This is a new source release, fixing recently discovered bugs in
previous MySQL Cluster NDB 6.3 releases.

Obtaining MySQL Cluster NDB 6.3

MySQL Cluster NDB 6.3 releases are source-only releases which you must
compile and install using the instructions found in *Note
installing-source::, and in *Note mysql-cluster-building::. You can
download the GPL source tarball from the MySQL FTP site at
`ftp://ftp.mysql.com/pub/mysql/download/cluster_telco/'.

This release incorporates all bugfixes and changes made in the previous
MySQL Cluster NDB 6.3 release, as well as all bugfixes and feature
changes which were added in mainline MySQL 5.1 through MySQL 5.1.24
(see *Note news-5-1-24::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *MySQL Cluster*: Event buffer lag reports are now written to the
     cluster log.  (Bug#37427 (http://bugs.mysql.com/37427))

   * *MySQL Cluster*: Added the `--no-binlog' option for `ndb_restore'.
     When used, this option prevents information being written to SQL
     node binary logs from the restoration of a cluster backup.
     (Bug#30452 (http://bugs.mysql.com/30452))

Bugs fixed:

   * *Cluster API*: *MySQL Cluster*: Changing the system time on data
     nodes could cause MGM API applications to hang and the data nodes
     to crash.  (Bug#35607 (http://bugs.mysql.com/35607))

   * *MySQL Cluster*: Failure of a data node could sometimes cause
     mysqld to crash.  (Bug#37628 (http://bugs.mysql.com/37628))

   * *MySQL Cluster*: `DELETE ... WHERE UNIQUE_INDEX_COLUMN=VALUE'
     deleted the wrong row from the table.  (Bug#37516
     (http://bugs.mysql.com/37516))

   * *MySQL Cluster*: If subscription was terminated while a node was
     down, the epoch was not properly acknowledged by that node.
     (Bug#37442 (http://bugs.mysql.com/37442))

   * *MySQL Cluster*: `libmysqld' failed to wait for the cluster binlog
     thread to terminate before exiting.  (Bug#37429
     (http://bugs.mysql.com/37429))

   * *MySQL Cluster*: In rare circumstances, a connection followed by a
     disconnection could give rise to a `stale' connection where the
     connection still existed but was not seen by the transporter.
     (Bug#37338 (http://bugs.mysql.com/37338))

   * *MySQL Cluster*: Queries against `NDBCLUSTER' tables were cached
     only if `AUTOCOMMIT' was in use.  (Bug#36692
     (http://bugs.mysql.com/36692))

   * *Cluster Replication*: Data was written to the binlog with
     `--log-slave-updates' disabled.  (Bug#37472
     (http://bugs.mysql.com/37472))

   * *Cluster API*: Creating a table on an SQL node, then starting an
     NDB API application that listened for events from this table, then
     dropping the table from an SQL node, prevented data node restarts.
     (Bug#37279 (http://bugs.mysql.com/37279))

   * *Cluster API*: When some operations succeeded and some failed
     following a call to `NdbTransaction::execute(Commit,
     AO_IgnoreOnError)', a race condition could cause spurious
     occurrences of NDB API Error 4011 (`Internal error').  (Bug#37158
     (http://bugs.mysql.com/37158))

   * *Cluster API*: A buffer overrun in `NdbBlob::setValue()' caused
     erroneous results on Mac OS X.  (Bug#31284
     (http://bugs.mysql.com/31284))


File: manual.info,  Node: mysql-cluster-news-5-1-24-ndb-6-3-15,  Next: mysql-cluster-news-5-1-24-ndb-6-3-14,  Prev: mysql-cluster-news-5-1-24-ndb-6-3-16,  Up: mysql-cluster-news-6-3

20.17.1.2 Changes in MySQL Cluster NDB 6.3.15 (5.1.24-ndb-6.3.15) (30 May 2008)
...............................................................................

This is a new source release, fixing recently discovered bugs in
previous MySQL Cluster NDB 6.3 releases.

Obtaining MySQL Cluster NDB 6.3

MySQL Cluster NDB 6.3 releases are source-only releases which you must
compile and install using the instructions found in *Note
installing-source::, and in *Note mysql-cluster-building::. You can
download the GPL source tarball from the MySQL FTP site at
`ftp://ftp.mysql.com/pub/mysql/download/cluster_telco/'.

This release incorporates all bugfixes and changes made in the previous
MySQL Cluster NDB 6.3 release, as well as all bugfixes and feature
changes which were added in mainline MySQL 5.1 through MySQL 5.1.24
(see *Note news-5-1-24::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Bugs fixed:

   * *MySQL Cluster*: In certain rare situations, `ndb_size.pl' could
     fail with the error `Can't use string ("VALUE") as a HASH ref
     while "strict refs" in use'.  (Bug#43022
     (http://bugs.mysql.com/43022))

   * *MySQL Cluster*: Under some circumstances, a failed `CREATE TABLE'
     could mean that subsequent `CREATE TABLE' statements caused node
     failures.  (Bug#37092 (http://bugs.mysql.com/37092))

   * *MySQL Cluster*: A fail attempt to create an `NDB' table could in
     some cases lead to resource leaks or cluster failures.  (Bug#37072
     (http://bugs.mysql.com/37072))

   * *MySQL Cluster*: Attempting to create a native backup of `NDB'
     tables having a large number of `NULL' columns and data could lead
     to node failures.  (Bug#37039 (http://bugs.mysql.com/37039))

   * *MySQL Cluster*: Checking of API node connections was not
     efficiently handled.  (Bug#36843 (http://bugs.mysql.com/36843))

   * *MySQL Cluster*: Attempting to delete a non-existent row from a
     table containing a `TEXT' or `BLOB' column within a transaction
     caused the transaction to fail.  (Bug#36756
     (http://bugs.mysql.com/36756)) See also Bug#36851
     (http://bugs.mysql.com/36851)

   * *MySQL Cluster*: If the combined total of tables and indexes in
     the cluster was greater than 4096, issuing `START BACKUP' caused
     data nodes to fail.  (Bug#36044 (http://bugs.mysql.com/36044))

   * *MySQL Cluster*: Where column values to be compared in a query
     were of the `VARCHAR' or `VARBINARY' types, `NDBCLUSTER' passed a
     value padded to the full size of the column, which caused
     unnecessary data to be sent to the data nodes. This also had the
     effect of wasting CPU and network bandwidth, and causing condition
     pushdown to be disabled where it could (and should) otherwise have
     been applied.  (Bug#35393 (http://bugs.mysql.com/35393))

   * *MySQL Cluster*: When dropping a table failed for any reason (such
     as when in single user mode) then the corresponding `.ndb' file
     was still removed.

   * *Replication*: When flushing tables, there was a slight chance
     that the flush occurred between the processing of one table map
     event and the next. Since the tables were opened one by one,
     subsequent locking of tables would cause the slave to crash. This
     problem was observed when replicating `NDBCLUSTER' or `InnoDB'
     tables, when executing multi-table updates, and when a trigger or
     a stored routine performed an (additional) insert on a table so
     that two tables were effectively being inserted into in the same
     statement.  (Bug#36197 (http://bugs.mysql.com/36197))

   * *Cluster API*: Ordered index scans were not pruned correctly where
     a partitioning key was specified with an EQ-bound.  (Bug#36950
     (http://bugs.mysql.com/36950))

   * *Cluster API*: When an insert operation involving `BLOB' data was
     attempted on a row which already existed, no duplicate key error
     was correctly reported and the transaction is incorrectly aborted.
     In some cases, the existing row could also become corrupted.
     (Bug#36851 (http://bugs.mysql.com/36851)) See also Bug#26756
     (http://bugs.mysql.com/26756)

   * *Cluster API*: `NdbApi.hpp' depended on `ndb_global.h', which was
     not actually installed, causing the compilation of programs that
     used `NdbApi.hpp' to fail.  (Bug#35853
     (http://bugs.mysql.com/35853))


File: manual.info,  Node: mysql-cluster-news-5-1-24-ndb-6-3-14,  Next: mysql-cluster-news-5-1-24-ndb-6-3-13,  Prev: mysql-cluster-news-5-1-24-ndb-6-3-15,  Up: mysql-cluster-news-6-3

20.17.1.3 Changes in MySQL Cluster NDB 6.3.14 (5.1.24-ndb-6.3.14) (11 May 2008)
...............................................................................

This is a new source release, fixing recently discovered bugs in
previous MySQL Cluster NDB 6.3 releases.

Obtaining MySQL Cluster NDB 6.3

MySQL Cluster NDB 6.3 releases are source-only releases which you must
compile and install using the instructions found in *Note
installing-source::, and in *Note mysql-cluster-building::. You can
download the GPL source tarball from the MySQL FTP site at
`ftp://ftp.mysql.com/pub/mysql/download/cluster_telco/'.

This release incorporates all bugfixes and changes made in the previous
MySQL Cluster NDB 6.3 release, as well as all bugfixes and feature
changes which were added in mainline MySQL 5.1 through MySQL 5.1.24
(see *Note news-5-1-24::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Bugs fixed:

   * *MySQL Cluster*: `SET GLOBAL ndb_extra_logging' caused `mysqld' to
     crash.  (Bug#36547 (http://bugs.mysql.com/36547))

   * *MySQL Cluster*: A race condition caused by a failure in epoll
     handling could cause data nodes to fail.  (Bug#36537
     (http://bugs.mysql.com/36537))

   * *MySQL Cluster*: Under certain rare circumstances, the failure of
     the new master node while attempting a node takeover would cause
     takeover errors to repeat without being resolved.  (Bug#36199
     (http://bugs.mysql.com/36199), Bug#36246
     (http://bugs.mysql.com/36246), Bug#36247
     (http://bugs.mysql.com/36247), Bug#36276
     (http://bugs.mysql.com/36276))

   * *MySQL Cluster*: When more than one SQL node connected to the
     cluster at the same time, creation of the `mysql.ndb_schema' table
     failed on one of them with an explicit `Table exists' error, which
     was not necessary.  (Bug#35943 (http://bugs.mysql.com/35943))

   * *MySQL Cluster*: `mysqld' failed to start after running
     `mysql_upgrade'.  (Bug#35708 (http://bugs.mysql.com/35708))

   * *MySQL Cluster*: Notification of a cascading master node failures
     could sometimes not be transmitted correctly (that is,
     transmission of the `NF_COMPLETEREP' signal could fail), leading to
     transactions hanging and timing out (`NDB' error 4012), scans
     hanging, and failure of the management server process.  (Bug#32645
     (http://bugs.mysql.com/32645))

   * *MySQL Cluster*: If an API node disconnected and then reconnected
     during Start Phase 8, then the connection could be `blocked' --
     that is, the `QMGR' kernel block failed to detect that the API
     node was in fact connected to the cluster, causing issues with the
     `NDB' Subscription Manager (`SUMA').

   * *MySQL Cluster*: `NDB' error 1427 (`Api node died, when
     SUB_START_REQ reached node') was incorrectly classified as a
     schema error rather than a temporary error.

   * *Cluster Replication*: Performing `SELECT ... FROM
     mysql.ndb_apply_status' before the `mysqld' process had connected
     to the cluster failed, and caused this table never to be created.
     (Bug#36123 (http://bugs.mysql.com/36123))

   * *Cluster API*: Accesing the debug version of `libndbclient' via
     `dlopen()' resulted in a segmentation fault.  (Bug#35927
     (http://bugs.mysql.com/35927))

   * *Cluster API*: Attempting to pass a nonexistent column name to the
     `equal()' and `setValue()' methods of `NdbOperation' caused NDB API
     applications to crash. Now the column name is checked, and an
     error is returned in the event that the column is not found.
     (Bug#33747 (http://bugs.mysql.com/33747))

   * *Cluster API*: Relocation errors were encountered when trying to
     compile NDB API applications on a number of platforms, including
     64-bit Linux. As a result, `libmysys', `libmystrings', and
     `libdbug' have been changed from normal libraries to `noinst'
     `libtool' helper libraries. They are no longer installed as
     separate libraries; instead, all necessary symbols from these are
     added directly to `libndbclient'. This means that NDB API programs
     now need to be linked only using `-lndbclient'.  (Bug#29791
     (http://bugs.mysql.com/29791))


File: manual.info,  Node: mysql-cluster-news-5-1-24-ndb-6-3-13,  Next: mysql-cluster-news-5-1-23-ndb-6-3-12,  Prev: mysql-cluster-news-5-1-24-ndb-6-3-14,  Up: mysql-cluster-news-6-3

20.17.1.4 Changes in MySQL Cluster NDB 6.3.13 (5.1.24-ndb-6.3.13) (10 April 2008)
.................................................................................

This is a new source release, fixing recently discovered bugs in
previous MySQL Cluster NDB 6.3 releases.

Obtaining MySQL Cluster NDB 6.3

MySQL Cluster NDB 6.3 releases are source-only releases which you must
compile and install using the instructions found in *Note
installing-source::, and in *Note mysql-cluster-building::. You can
download the GPL source tarball from the MySQL FTP site at
`ftp://ftp.mysql.com/pub/mysql/download/cluster_telco/'.

This release incorporates all bugfixes and changes made in the previous
MySQL Cluster NDB 6.3 release, as well as all bugfixes and feature
changes which were added in mainline MySQL 5.1 through MySQL 5.1.24
(see *Note news-5-1-24::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * The `ndbd' and `ndb_mgmd' manpages have been reclassified from
     volume 1 to volume 8.  (Bug#34642 (http://bugs.mysql.com/34642))

Bugs fixed:

   * *Important Change*: *MySQL Cluster*: `mysqld_safe' now traps
     Signal 13 (`SIGPIPE') so that this signal no longer kills the
     MySQL server process.  (Bug#33984 (http://bugs.mysql.com/33984))

   * *MySQL Cluster*: Node or system restarts could fail due an
     unitialized variable in the `DTUP' kernel block. This issue was
     found in MySQL Cluster NDB 6.3.11.  (Bug#35797
     (http://bugs.mysql.com/35797))

   * *MySQL Cluster*: If an error occured while executing a statement
     involving a `BLOB' or `TEXT' column of an `NDB' table, a memory
     leak could result.  (Bug#35593 (http://bugs.mysql.com/35593))

   * *MySQL Cluster*: It was not possible to determine the value used
     for the `--ndb-cluster-connection-pool' option in the `mysql'
     client. Now this value is reported as a system status variable.
     (Bug#35573 (http://bugs.mysql.com/35573))

   * *MySQL Cluster*: The `ndb_waiter' utility wrongly calculated
     timeouts.  (Bug#35435 (http://bugs.mysql.com/35435))

   * *MySQL Cluster*: A `SELECT' on a table with a non-indexed, large
     `VARCHAR' column which resulted in condition pushdown on this
     column could cause `mysqld' to crash.  (Bug#35413
     (http://bugs.mysql.com/35413))

   * *MySQL Cluster*: `ndb_restore' incorrectly handled some datatypes
     when applying log files from backups.  (Bug#35343
     (http://bugs.mysql.com/35343))

   * *MySQL Cluster*: In some circumstances, a stopped data node was
     handled incorrectly, leading to redo log space being exhausted
     following an initial restart of the node, or an initial or partial
     restart of the cluster (the wrong CGI might be used in such
     cases). This could happen, for example, when a node was stopped
     following the creation of a new table, but before a new LCP could
     be executed.  (Bug#35241 (http://bugs.mysql.com/35241))

   * *MySQL Cluster*: `SELECT ... LIKE ...' queries yielded incorrect
     results when used on `NDB' tables. As part of this fix, condition
     pushdown of such queries has been disabled; re-enabling it is
     expected to be done as part of a later, permanent fix for this
     issue.  (Bug#35185 (http://bugs.mysql.com/35185))

   * *MySQL Cluster*: `ndb_mgmd' reported errors to `STDOUT' rather
     than to `STDERR'.  (Bug#35169 (http://bugs.mysql.com/35169))

   * *MySQL Cluster*: Nested multi-range reads failed when the second
     multi-range read released the first read's unprocessed operations,
     sometimes leading to a SQL node crash.  (Bug#35137
     (http://bugs.mysql.com/35137))

   * *MySQL Cluster*: In some situations, a problem with synchronizing
     checkpoints between nodes could cause a system restart or a node
     restart to fail with `Error 630 during restore of TX'.  (Bug#34756
     (http://bugs.mysql.com/34756))

   * *MySQL Cluster*: A node failure during an initial node restart
     followed by another node start could cause the master data node to
     fail, because it incorrectly gave the node permission to start
     even if the invalidated node's LCP was still running.  (Bug#34702
     (http://bugs.mysql.com/34702))

   * *MySQL Cluster*: When a secondary index on a `DECIMAL' column was
     used to retrieve data from an `NDB' table, no results were
     returned even if the target table had a matched value in the
     column that was defined with the secondary index.  (Bug#34515
     (http://bugs.mysql.com/34515))

   * *MySQL Cluster*: An `UPDATE' on an `NDB' table that set a new
     value for a unique key column could cause subsequent queries to
     fail.  (Bug#34208 (http://bugs.mysql.com/34208))

   * *MySQL Cluster*: If a data node in one node group was placed in
     the `not started' state (using `NODE_ID RESTART -n'), it was not
     possible to stop a data node in a different node group.
     (Bug#34201 (http://bugs.mysql.com/34201))

   * *MySQL Cluster*: Numerous `NDBCLUSTER' test failures occurred in
     builds compiled using `icc' on IA64 platforms.  (Bug#31239
     (http://bugs.mysql.com/31239))

   * *MySQL Cluster*: If a `START BACKUP' command was issued while
     `ndb_restore' was running, the backup being restored could be
     overwritten.  (Bug#26498 (http://bugs.mysql.com/26498))

   * *MySQL Cluster*: `REPLACE' statements did not work correctly with
     `NDBCLUSTER' tables when all columns were not explicitly listed.
     (Bug#22045 (http://bugs.mysql.com/22045))

   * *MySQL Cluster*: `CREATE TABLE' and `ALTER TABLE' statements using
     `ENGINE=NDB' or `ENGINE=NDBCLUSTER' caused `mysqld' to fail on
     Solaris 10 for x86 platforms.  (Bug#19911
     (http://bugs.mysql.com/19911))

   * *Replication*: A `CHANGE MASTER' statement with no
     `MASTER_HEARTBEAT_PERIOD' option failed to reset the heartbeat
     period to its default value.  (Bug#34686
     (http://bugs.mysql.com/34686))

   * *Cluster Replication*: In some cases, when updating only one or
     some columns in a table, the complete row was written to the
     binary log instead of only the updated column or columns, even when
     `ndb_log_updated_only' was set to 1.  (Bug#35208
     (http://bugs.mysql.com/35208))

   * *Cluster Replication*: The `--ndb-wait-connected' option caused the
     server to wait for a partial connection plus an additional 3
     seconds for a complete connection to the cluster. This could lead
     to issues with setting up the binary log.  (Bug#34757
     (http://bugs.mysql.com/34757))

   * *Cluster API*: Closing a scan before it was executed caused the
     application to segfault.  (Bug#36375 (http://bugs.mysql.com/36375))

   * *Cluster API*: Using NDB API applications from older MySQL Cluster
     versions with `libndbclient' from newer ones caused the cluster to
     fail.  (Bug#36124 (http://bugs.mysql.com/36124))

   * *Cluster API*: Some ordered index scans could return tuples out of
     order.  (Bug#35908 (http://bugs.mysql.com/35908))

   * *Cluster API*: Scans having no bounds set were handled incorrectly.
     (Bug#35876 (http://bugs.mysql.com/35876))

   * *Cluster API*: `NdbScanFilter::getNdbOperation()', which was
     inadvertently removed in MySQL Cluster NDB 6.3.11, has been
     restored.  (Bug#35854 (http://bugs.mysql.com/35854))

   * Enabling the `read_only' system variable while autocommit mode was
     enabled caused `SELECT' statements for transactional storage
     engines to fail.  (Bug#35732 (http://bugs.mysql.com/35732))

   * Executing a `FLUSH PRIVILEGES' statement after creating a
     temporary table in the `mysql' database with the same name as one
     of the MySQL system tables caused the server to crash.

     *Note*:

     While it is possible to shadow a system table in this way, the
     temporary table exists only for the current user and connection,
     and does not effect any user privileges.

     (Bug#33275 (http://bugs.mysql.com/33275))


File: manual.info,  Node: mysql-cluster-news-5-1-23-ndb-6-3-12,  Next: mysql-cluster-news-5-1-23-ndb-6-3-11,  Prev: mysql-cluster-news-5-1-24-ndb-6-3-13,  Up: mysql-cluster-news-6-3

20.17.1.5 Changes in MySQL Cluster NDB 6.3.12 (5.1.23-ndb-6.3.12) (05 April 2008)
.................................................................................

MySQL Cluster NDB 6.3.12 was pulled due to issues discovered shortly
after its release, and is no longer available. Users of MySQL Cluster
NDB 6.3.10 and earlier MySQL Cluster NDB 6.3 releases should upgrade to
MySQL Cluster NDB 6.3.13 or later.

For information about bugfixes and feature enhancements that were
originally scheduled to appear for the first time in this release, see
*Note mysql-cluster-news-5-1-24-ndb-6-3-13::.


File: manual.info,  Node: mysql-cluster-news-5-1-23-ndb-6-3-11,  Next: mysql-cluster-news-5-1-23-ndb-6-3-10,  Prev: mysql-cluster-news-5-1-23-ndb-6-3-12,  Up: mysql-cluster-news-6-3

20.17.1.6 Changes in MySQL Cluster NDB 6.3.11 (5.1.23-ndb-6.3.11) (28 March 2008)
.................................................................................

This release was pulled due to issues discovered shortly after its
release, and is no longer available. Users of MySQL Cluster NDB 6.3.10
and earlier MySQL Cluster NDB 6.3 releases should upgrade to MySQL
Cluster NDB 6.3.13 or later.

For information about bugfixes and feature enhancements that were
originally scheduled to appear for the first time in this release, see
*Note mysql-cluster-news-5-1-24-ndb-6-3-13::.


File: manual.info,  Node: mysql-cluster-news-5-1-23-ndb-6-3-10,  Next: mysql-cluster-news-5-1-23-ndb-6-3-9,  Prev: mysql-cluster-news-5-1-23-ndb-6-3-11,  Up: mysql-cluster-news-6-3

20.17.1.7 Changes in MySQL Cluster NDB 6.3.10 (5.1.23-ndb-6.3.10) (17 February 2008)
....................................................................................

This is a new Beta development release, fixing recently discovered bugs
in previous MySQL Cluster NDB 6.3 releases.

Obtaining MySQL Cluster NDB 6.3

MySQL Cluster NDB 6.3 releases are source-only releases which you must
compile and install using the instructions found in *Note
installing-source::, and in *Note mysql-cluster-building::. You can
download the GPL source tarball from the MySQL FTP site at
`ftp://ftp.mysql.com/pub/mysql/download/cluster_telco/'.

This Beta release incorporates all bugfixes and changes made in the
previous MySQL Cluster NDB 6.3 release, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.23 (see *Note news-5-1-23::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Bugs fixed:

   * *MySQL Cluster*: Due to the reduction of the number of local
     checkpoints from 3 to 2 in MySQL Cluster NDB 6.3.8, a data node
     using ndbd from MySQL Cluster NDB 6.3.8 or later started using a
     filesystem from an earlier version could incorrectly invalidate
     local checkpoints too early during the startup process, causing the
     node to fail.  (Bug#34596 (http://bugs.mysql.com/34596))


File: manual.info,  Node: mysql-cluster-news-5-1-23-ndb-6-3-9,  Next: mysql-cluster-news-5-1-23-ndb-6-3-8,  Prev: mysql-cluster-news-5-1-23-ndb-6-3-10,  Up: mysql-cluster-news-6-3

20.17.1.8 Changes in MySQL Cluster NDB 6.3.9 (5.1.23-ndb-6.3.9) (12 February 2008)
..................................................................................

This is a new Beta development release, fixing recently discovered bugs
in previous MySQL Cluster NDB 6.3 releases.

Obtaining MySQL Cluster NDB 6.3

MySQL Cluster NDB 6.3 releases are source-only releases which you must
compile and install using the instructions found in *Note
installing-source::, and in *Note mysql-cluster-building::. You can
download the GPL source tarball from the MySQL FTP site at
`ftp://ftp.mysql.com/pub/mysql/download/cluster_telco/'.

This Beta release incorporates all bugfixes and changes made in the
previous MySQL Cluster NDB 6.3 release, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.23 (see *Note news-5-1-23::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * Beginning with this version, MySQL Cluster NDB 6.3.X releases once
     again include the `InnoDB' storage engine. In order to enable
     `InnoDB', you must configure the build using `--with-innodb'.

Bugs fixed:

   * *MySQL Cluster*: Cluster failures could sometimes occur when
     performing more than three parallel takeovers during node restarts
     or system restarts. This affected MySQL Cluster NDB 6.3.X releases
     only.  (Bug#34445 (http://bugs.mysql.com/34445))

   * *MySQL Cluster*: Upgrades of a cluster using while a `DataMemory'
     setting in excess of 16 GB caused data nodes to fail.  (Bug#34378
     (http://bugs.mysql.com/34378))

   * *MySQL Cluster*: Performing many SQL statements on `NDB' tables
     while in `AUTOCOMMIT' mode caused a memory leak in `mysqld'.
     (Bug#34275 (http://bugs.mysql.com/34275))

   * *MySQL Cluster*: In certain rare circumstances, a race condition
     could occur between an aborted insert and a delete leading a data
     node crash.  (Bug#34260 (http://bugs.mysql.com/34260))

   * *MySQL Cluster*: Multi-table updates using ordered indexes during
     handling of node failures could cause other data nodes to fail.
     (Bug#34216 (http://bugs.mysql.com/34216))

   * *MySQL Cluster*: When configured with `NDB' support, MySQL failed
     to compile using `gcc' 4.3 on 64bit FreeBSD systems.  (Bug#34169
     (http://bugs.mysql.com/34169))

   * *MySQL Cluster*: The failure of a DDL statement could sometimes
     lead to node failures when attempting to execute subsequent DDL
     statements.  (Bug#34160 (http://bugs.mysql.com/34160))

   * *MySQL Cluster*: Extremely long `SELECT' statements (where the
     text of the statement was in excess of 50000 characters) against
     `NDB' tables returned empty results.  (Bug#34107
     (http://bugs.mysql.com/34107))

   * *MySQL Cluster*: When configured with `NDB' support, MySQL failed
     to compile on 64bit FreeBSD systems.  (Bug#34046
     (http://bugs.mysql.com/34046))

   * *MySQL Cluster*: Statements executing multiple inserts performed
     poorly on `NDB' tables having `AUTO_INCREMENT' columns.
     (Bug#33534 (http://bugs.mysql.com/33534))

   * *MySQL Cluster*: The `ndb_waiter' utility polled `ndb_mgmd'
     excessively when obtaining the status of cluster data nodes.
     (Bug#32025 (http://bugs.mysql.com/32025)) See also Bug#32023
     (http://bugs.mysql.com/32023)

   * *MySQL Cluster*: Transaction atomicity was sometimes not preserved
     between reads and inserts under high loads.  (Bug#31477
     (http://bugs.mysql.com/31477))

   * *MySQL Cluster*: Having tables with a great many columns could
     cause Cluster backups to fail.  (Bug#30172
     (http://bugs.mysql.com/30172))

   * *Cluster Replication*: *Disk Data*: Statements violating unique
     keys on Disk Data tables (such as attempting to insert `NULL' into
     a `NOT NULL' column) could cause data nodes to fail. When the
     statement was executed from the binlog, this could also result in
     failure of the slave cluster.  (Bug#34118
     (http://bugs.mysql.com/34118))

   * *Disk Data*: Updating in-memory columns of one or more rows of
     Disk Data table, followed by deletion of these rows and
     re-insertion of them, caused data node failures.  (Bug#33619
     (http://bugs.mysql.com/33619))

   * *Cluster Replication*: Setting `--replicate-ignore-db=mysql'
     caused the `mysql.ndb_apply_status' table not to be replicated,
     breaking Cluster Replication.  (Bug#28170
     (http://bugs.mysql.com/28170))


File: manual.info,  Node: mysql-cluster-news-5-1-23-ndb-6-3-8,  Next: mysql-cluster-news-5-1-23-ndb-6-3-7,  Prev: mysql-cluster-news-5-1-23-ndb-6-3-9,  Up: mysql-cluster-news-6-3

20.17.1.9 Changes in MySQL Cluster NDB 6.3.8 (5.1.23-ndb-6.3.8) (29 January 2008)
.................................................................................

This is a new Beta development release, fixing recently discovered bugs
in previous MySQL Cluster NDB 6.3 releases.

Obtaining MySQL Cluster NDB 6.3

MySQL Cluster NDB 6.3 releases are source-only releases which you must
compile and install using the instructions found in *Note
installing-source::, and in *Note mysql-cluster-building::. You can
download the GPL source tarball from the MySQL FTP site at
`ftp://ftp.mysql.com/pub/mysql/download/cluster_telco/'.

This Beta release incorporates all bugfixes and changes made in the
previous MySQL Cluster NDB 6.3 release, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.23 (see *Note news-5-1-23::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *Cluster API*: *Important Change*: Because
     `NDB_LE_MemoryUsage.page_size_kb' shows memory page sizes in bytes
     rather than kilobytes, it has been renamed to `page_size_bytes'.
     The name `page_size_kb' is now deprecated and thus subject to
     removal in a future release, although it currently remains
     supported for reasons of backward compatibility. See The
     `Ndb_logevent_type' Type
     (http://dev.mysql.com/doc/ndbapi/en/ndb-logevent-type.html), for
     more information about `NDB_LE_MemoryUsage'.  (Bug#30271
     (http://bugs.mysql.com/30271))

   * *MySQL Cluster*: `ndb_restore' now supports basic _attribute
     promotion_; that is, data from a column of a given type can be
     restored to a column using a `larger' type. For example, Cluster
     backup data taken from a `SMALLINT' column can be restored to a
     `MEDIUMINT', `INT', or `BIGINT' column.

     For more information, see *Note mysql-cluster-restore::.

   * *MySQL Cluster*: Now only 2 local checkpoints are stored, rather
     than 3 as in previous MySQL Cluster versions. This lowers disk
     space requirements and reduces the size and number of redo log
     files needed.

   * *MySQL Cluster*: The `mysqld' option `--ndb-batch-size' has been
     added. This allows for controlling the size of batches used for
     running transactions.

   * *MySQL Cluster*: Node recovery can now be done in parallel, rather
     than sequentially, which can result in much faster recovery times.

   * *MySQL Cluster*: Persistence of `NDB' tables can now be controlled
     using the session variables `ndb_table_temporary' and
     `ndb_table_no_logging'.  `ndb_table_no_logging' causes `NDB'
     tables not to be checkpointed to disk; `ndb_table_temporary' does
     the same, and in addition, no schema files are created.

   * *MySQL Cluster*: `OPTIMIZE TABLE' can now be interrupted. This can
     be done, for example, by killing the SQL thread performing the
     `OPTIMIZE' operation.

Bugs fixed:

   * *Disk Data*: *Important Change*: It is no longer possible on
     32-bit systems to issue statements appearing to create Disk Data
     log files or data files greater than 4 GB in size. (Trying to
     create log files or data files larger than 4 GB on 32-bit systems
     led to unrecoverable data node failures; such statements now fail
     with `NDB' error 1515.)  (Bug#29186 (http://bugs.mysql.com/29186))

   * *Replication*: *MySQL Cluster*: The code implementing heartbeats
     did not check for possible errors in some circumstances; this kept
     the dump thread hanging while waiting for heartbeats loop even
     though the slave was no longer connected.  (Bug#33332
     (http://bugs.mysql.com/33332))

   * *MySQL Cluster*: High numbers of insert operations, delete
     operations, or both could cause `NDB' error 899 (`Rowid already
     allocated') to occur unnecessarily.  (Bug#34033
     (http://bugs.mysql.com/34033))

   * *MySQL Cluster*: A periodic failure to flush the send buffer by the
     `NDB' TCP transporter could cause a unnecessary delay of 10 ms
     between operations.  (Bug#34005 (http://bugs.mysql.com/34005))

   * *MySQL Cluster*: `DROP TABLE' did not free all data memory. This
     bug was observed in MySQL Cluster NDB 6.3.7 only.  (Bug#33802
     (http://bugs.mysql.com/33802))

   * *MySQL Cluster*: A race condition could occur (very rarely) when
     the release of a GCI was followed by a data node failure.
     (Bug#33793 (http://bugs.mysql.com/33793))

   * *MySQL Cluster*: Some tuple scans caused the wrong memory page to
     be accessed, leading to invalid results. This issue could affect
     both in-memory and Disk Data tables.  (Bug#33739
     (http://bugs.mysql.com/33739))

   * *MySQL Cluster*: A failure to initialize an internal variable led
     to sporadic crashes during cluster testing.  (Bug#33715
     (http://bugs.mysql.com/33715))

   * *MySQL Cluster*: The server failed to reject properly the creation
     of an `NDB' table having an unindexed `AUTO_INCREMENT' column.
     (Bug#30417 (http://bugs.mysql.com/30417))

   * *MySQL Cluster*: Issuing an `INSERT ... ON DUPLICATE KEY UPDATE'
     concurrently with or following a `TRUNCATE' statement on an `NDB'
     table failed with `NDB' error 4350 `Transaction already aborted'.
     (Bug#29851 (http://bugs.mysql.com/29851))

   * *MySQL Cluster*: The Cluster backup process could not detect when
     there was no more disk space and instead continued to run until
     killed manually. Now the backup fails with an appropriate error
     when disk space is exhausted.  (Bug#28647
     (http://bugs.mysql.com/28647))

   * *MySQL Cluster*: It was possible in `config.ini' to define cluster
     nodes having node IDs greater than the maximum allowed value.
     (Bug#28298 (http://bugs.mysql.com/28298))

   * *MySQL Cluster*: Under some circumstances, a recovering data node
     did not use its own data, instead copying data from another node
     even when this was not required. This in effect bypassed the
     optimized node recovery protocol and caused recovery times to be
     unnecessarily long.  (Bug#26913 (http://bugs.mysql.com/26913))

   * *Cluster Replication*: Consecutive DDL statements involving tables
     (`CREATE TABLE', `ALTER TABLE', and `DROP TABLE') could be
     executed so quickly that previous DDL statements upon which they
     depended were not yet written in the binary log.

     For example, if `DROP TABLE foo' was issued immediately following
     `CREATE TABLE foo', the `DROP' statement could fail because the
     `CREATE' had not yet been recorded.  (Bug#34006
     (http://bugs.mysql.com/34006))

   * *Cluster Replication*: `ndb_restore -e' restored excessively large
     values to the `ndb_apply_status' table's `epoch' column when
     restoring to a MySQL Cluster version supporting Micro-GCPs from an
     older version that did not support these.

     A workaround when restoring to MySQL Cluster releases supporting
     micro-GCPs previous to MySQL Cluster NDB 6.3.8 is to perform a
     32-bit shift on the `epoch' column values to reduce them to their
     proper size.  (Bug#33406 (http://bugs.mysql.com/33406))

   * *Cluster API*: Transactions containing inserts or reads would hang
     during `NdbTransaction::execute()' calls made from NDB API
     applications built against a MySQL Cluster version that did not
     support micro-GCPs accessing a later version that supported
     micro-GCPs. This issue was observed while upgrading from MySQL
     Cluster NDB 6.1.23 to MySQL Cluster NDB 6.2.10 when the API
     application built against the earlier version attempted to access
     a data node already running the later version, even after
     disabling micro-GCPs by setting `TimeBetweenEpochs' equal to 0.
     (Bug#33895 (http://bugs.mysql.com/33895))

   * *Cluster API*: When reading a `BIT(64)' value using
     `NdbOperation:getValue()', 12 bytes were written to the buffer
     rather than the expected 8 bytes.  (Bug#33750
     (http://bugs.mysql.com/33750))


File: manual.info,  Node: mysql-cluster-news-5-1-23-ndb-6-3-7,  Next: mysql-cluster-news-5-1-22-ndb-6-3-6,  Prev: mysql-cluster-news-5-1-23-ndb-6-3-8,  Up: mysql-cluster-news-6-3

20.17.1.10 Changes in MySQL Cluster NDB 6.3.7 (5.1.23-ndb-6.3.7) (19 December 2007)
...................................................................................

This is a new Beta development release, fixing recently discovered bugs
in previous MySQL Cluster NDB 6.3 releases.

Obtaining MySQL Cluster NDB 6.3

MySQL Cluster NDB 6.3 releases are source-only releases which you must
compile and install using the instructions found in *Note
installing-source::, and in *Note mysql-cluster-building::. You can
download the GPL source tarball from the MySQL FTP site at
`ftp://ftp.mysql.com/pub/mysql/download/cluster_telco/'.

This Beta release incorporates all bugfixes and changes made in the
previous MySQL Cluster NDB 6.3 release, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.23 (see *Note news-5-1-23::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *MySQL Cluster*: Compressed local checkpoints and backups are now
     supported, resulting in a space savings of 50% or more over
     uncompressed LCPs and backups. Cmpression of these can be enabled
     in the `config.ini' file using the two new data node configuration
     parameters `CompressedLCP' and `CompressedBackup', respectively.

   * *MySQL Cluster*: `OPTIMIZE TABLE' is now supported for `NDB'
     tables, subject to the following limitations:

        * Only in-memory tables are supported.  `OPTIMIZE' still has no
          effect on Disk Data tables.

        * Only variable-length columns are supported. However, you can
          force columns defined using fixed-length data types to be
          dynamic using the `ROW_FORMAT' or `COLUMN_FORMAT' option with
          a `CREATE TABLE' or `ALTER TABLE' statement.

     Memory reclaimed from an `NDB' table using `OPTIMIZE' is generally
     available to the cluster, and not confined to the table from which
     it was recovered, unlike the case with memory freed using `DELETE'.

     The performance of `OPTIMIZE' on `NDB' tables can be regulated by
     adjusting the value of the `ndb_optimization_delay' system
     variable.

   * *MySQL Cluster*: It is now possible to cause statements occurring
     within the same transaction to be run as a batch by setting the
     session variable `transaction_allow_batching' to `1' or `ON'.

     *Note*:

     To use this feature, autocommit must be disabled.

Bugs fixed:

   * *Partitioning*: *MySQL Cluster*: When partition pruning on an
     `NDB' table resulted in an ordered index scan spanning only one
     partition, any descending flag for the scan was wrongly discarded,
     causing `ORDER BY DESC' to be treated as `ORDER BY ASC', `MAX()'
     to be handled incorrectly, and similar problems.  (Bug#33061
     (http://bugs.mysql.com/33061))

   * *MySQL Cluster*: When all data and SQL nodes in the cluster were
     shut down abnormally (that is, other than by using `STOP' in the
     cluster management client), `ndb_mgm' used excessive amounts of
     CPU.  (Bug#33237 (http://bugs.mysql.com/33237))

   * *MySQL Cluster*: When using micro-GCPs, if a node failed while
     preparing for a global checkpoint, the master node would use the
     wrong GCI.  (Bug#32922 (http://bugs.mysql.com/32922))

   * *MySQL Cluster*: Under some conditions, performing an `ALTER
     TABLE' on an `NDBCLUSTER' table failed with a `Table is full'
     error, even when only 25% of `DataMemory' was in use and the
     result should have been a table using less memory (for example,
     changing a `VARCHAR(100)' column to `VARCHAR(80)').  (Bug#32670
     (http://bugs.mysql.com/32670))

   * *Cluster Replication*: Creating the `mysql.ndb_replication' table
     with the wrong number of columns for the primary key caused
     `mysqld' to crash. Now a `CREATE TABLE [mysql.]ndb_replication'
     statement that is invalid for this reason fails with the error
     `Bad schema for mysql.ndb_replication table. Message: Wrong number
     of primary keys, expected NUMBER'.  (Bug#33159
     (http://bugs.mysql.com/33159))

   * *Cluster Replication*: Where a table being replicated had a `TEXT'
     or `BLOB' column, an `UPDATE' on the master that did not refer
     explicitly to this column in the `WHERE' clause stopped the SQL
     thread on the slave with `Error in Write_rows event: row
     application failed. Got error 4288 'Blob handle for column not
     available' from NDBCLUSTER'.  (Bug#30674
     (http://bugs.mysql.com/30674))


File: manual.info,  Node: mysql-cluster-news-5-1-22-ndb-6-3-6,  Next: mysql-cluster-news-5-1-22-ndb-6-3-5,  Prev: mysql-cluster-news-5-1-23-ndb-6-3-7,  Up: mysql-cluster-news-6-3

20.17.1.11 Changes in MySQL Cluster NDB 6.3.6 (5.1.22-ndb-6.3.6) (08 November 2007)
...................................................................................

This is a new Beta development release, fixing recently discovered bugs
in previous MySQL Cluster NDB 6.3 releases.

Obtaining MySQL Cluster NDB 6.3

MySQL Cluster NDB 6.3 releases are source-only releases which you must
compile and install using the instructions found in *Note
installing-source::, and in *Note mysql-cluster-building::. You can
download the GPL source tarball from the MySQL FTP site at
`ftp://ftp.mysql.com/pub/mysql/download/cluster_telco/'.

This Beta release incorporates all bugfixes and changes made in the
previous MySQL Cluster NDB 6.3 release, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.22 (see *Note news-5-1-22::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *Important Note*: MySQL Cluster NDB 6.2 and 6.3 source archives
     are now available in separate commercial and GPL versions. Due to
     licensing concerns, previous MySQL Cluster NDB 6.2 and 6.3 source
     archives were removed from the FTP site.

   * *MySQL Cluster*: Unnecessary reads when performing a primary key
     or unique key update have been reduced, and in some cases,
     eliminated. (It is almost never necessary to read a record prior
     to an update, the lone exception to this being when a primary key
     is updated, since this requires a delete followed by an insert,
     which must be prepared by reading the record.) Depending on the
     number of primary key and unique key lookups that are performed per
     transaction, this can yield a considerable improvement in
     performance.

   * *MySQL Cluster*: Batched operations are now better supported for
     `DELETE' and `UPDATE'.  (`UPDATE WHERE...' and muliple `DELETE'.)

   * *MySQL Cluster*: Introduced the `Ndb_execute_count' status
     variable, which measures the number of round trips made by queries
     to the `NDB' kernel.

Bugs fixed:

   * *MySQL Cluster*: An insert or update with combined range and
     equality constraints failed when run against an `NDB' table with
     the error `Got unknown error from NDB'. An example of such a
     statement would be `UPDATE t1 SET b = 5 WHERE a IN (7,8) OR a >=
     10;'.  (Bug#31874 (http://bugs.mysql.com/31874))

   * *MySQL Cluster*: An error with an `if' statement in
     `sql/ha_ndbcluster.cc' could potentially lead to an infinite loop
     in case of failure when working with `AUTO_INCREMENT' columns in
     `NDB' tables.  (Bug#31810 (http://bugs.mysql.com/31810))

   * *MySQL Cluster*: The `NDB' storage engine code was not safe for
     strict-alias optimization in `gcc' 4.2.1.  (Bug#31761
     (http://bugs.mysql.com/31761))

   * *MySQL Cluster*: `ndb_restore' displayed incorrect backup file
     version information. This meant (for example) that, when
     attempting to restore a backup made from a MySQL 5.1.22 cluster to
     a MySQL Cluster NDB 6.3.3 cluster, the restore process failed with
     the error `Restore program older than backup version. Not
     supported. Use new restore program.' (Bug#31723
     (http://bugs.mysql.com/31723))

   * *MySQL Cluster*: Following an upgrade, `ndb_mgmd' would fail with
     an ArbitrationError.  (Bug#31690 (http://bugs.mysql.com/31690))

   * *MySQL Cluster*: The `NDB' management client command `NODE_ID
     REPORT MEMORY' provided no output when NODE_ID was the node ID of a
     management or API node. Now, when this occurs, the management
     client responds with `Node NODE_ID: is not a data node'.
     (Bug#29485 (http://bugs.mysql.com/29485))

   * *MySQL Cluster*: Performing `DELETE' operations after a data node
     had been shut down could lead to inconsistent data following a
     restart of the node.  (Bug#26450 (http://bugs.mysql.com/26450))

   * *MySQL Cluster*: `UPDATE IGNORE' could sometimes fail on `NDB'
     tables due to the use of unitialized data when checking for
     duplicate keys to be ignored.  (Bug#25817
     (http://bugs.mysql.com/25817))

   * *Cluster Replication*: Updates performed unnecessary writes to the
     primary keys of the rows being updated.  (Bug#31841
     (http://bugs.mysql.com/31841))

   * *Cluster Replication*: Slave batching did not work correctly with
     `UPDATE' statements.  (Bug#31787 (http://bugs.mysql.com/31787))

   * *Cluster Replication*: A node failure during replication could
     lead to buckets out of order; now active subscribers are checked
     for, rather than empty buckets.  (Bug#31701
     (http://bugs.mysql.com/31701))

   * *Cluster Replication*: When the master `mysqld' crashed or was
     restarted, no `LOST_EVENTS' entry was made in the binlog.
     (Bug#31484 (http://bugs.mysql.com/31484)) See also Bug#21494
     (http://bugs.mysql.com/21494)


File: manual.info,  Node: mysql-cluster-news-5-1-22-ndb-6-3-5,  Next: mysql-cluster-news-5-1-22-ndb-6-3-4,  Prev: mysql-cluster-news-5-1-22-ndb-6-3-6,  Up: mysql-cluster-news-6-3

20.17.1.12 Changes in MySQL Cluster NDB 6.3.5 (5.1.22-ndb-6.3.5) (17 October 2007)
..................................................................................

This is a new Beta development release, fixing recently discovered bugs
in previous MySQL Cluster NDB 6.3 releases.

Obtaining MySQL Cluster NDB 6.3

MySQL Cluster NDB 6.3 releases are source-only releases which you must
compile and install using the instructions found in *Note
installing-source::, and in *Note mysql-cluster-building::. You can
download the GPL source tarball from the MySQL FTP site at
`ftp://ftp.mysql.com/pub/mysql/download/cluster_telco/'.

This Beta release incorporates all bugfixes and changes made in the
previous MySQL Cluster NDB 6.3 release, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.22 (see *Note news-5-1-22::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Bugs fixed:

   * *MySQL Cluster*: A query against a table with `TEXT' or `BLOB'
     columns that would return more than a certain amount of data
     failed with `Got error 4350 'Transaction already aborted' from
     NDBCLUSTER'.  (Bug#31482 (http://bugs.mysql.com/31482)) This
     regression was introduced by Bug#29102
     (http://bugs.mysql.com/29102)

   * *Cluster Replication*: In some cases, not all tables were properly
     initialized before the binlog thread was started.  (Bug#31618
     (http://bugs.mysql.com/31618))


File: manual.info,  Node: mysql-cluster-news-5-1-22-ndb-6-3-4,  Next: mysql-cluster-news-5-1-22-ndb-6-3-3,  Prev: mysql-cluster-news-5-1-22-ndb-6-3-5,  Up: mysql-cluster-news-6-3

20.17.1.13 Changes in MySQL Cluster NDB 6.3.4 (5.1.22-ndb-6.3.4) (15 October 2007)
..................................................................................

This is a new Beta development release, fixing recently discovered bugs
in previous MySQL Cluster NDB 6.3 releases.

Obtaining MySQL Cluster NDB 6.3

MySQL Cluster NDB 6.3 releases are source-only releases which you must
compile and install using the instructions found in *Note
installing-source::, and in *Note mysql-cluster-building::. You can
download the GPL source tarball from the MySQL FTP site at
`ftp://ftp.mysql.com/pub/mysql/download/cluster_telco/'.

This Beta release incorporates all bugfixes and changes made in the
previous MySQL Cluster NDB 6.3 release, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.22 (see *Note news-5-1-22::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *MySQL Cluster*: The `--ndb_optimized_node_selection' startup
     option for `mysqld' now allows a wider range of values and
     corresponding behaviors for SQL nodes when selecting a transaction
     coordinator. See *Note server-system-variables::, for more
     information.

   * *Cluster Replication*: *Replication*: A replication heartbeat
     mechanism has been added to facilitate monitoring. This provides
     an alternative to checking log files, making it possible to detect
     in real time when a slave has failed.

     Configuration of heartbeats is done via a new
     `MASTER_HEARTBEAT_PERIOD = INTERVAL' clause for the `CHANGE MASTER
     TO' statement (see *Note change-master-to::); monitoring can be
     done by checking the values of the status variables
     `Slave_heartbeat_period' and `Slave_received_heartbeats' (see
     *Note server-status-variables::).

     The addition of replication heartbeats addresses a number of
     issues:

        * Relay logs were rotated every `slave_net_timeout' seconds
          even if no statements were being replicated.

        * `SHOW SLAVE STATUS' displayed an incorrect value for
          `seconds_behind_master' following a `FLUSH LOGS' statement.

        * Replication master-slave connections used `slave_net_timeout'
          for connection timeouts.

     (Bug#20435 (http://bugs.mysql.com/20435), Bug#29309
     (http://bugs.mysql.com/29309), Bug#30932
     (http://bugs.mysql.com/30932))

   * *Cluster Replication*: A new configuration parameter
     `TimeBetweenEpochsTimeout' allows a timeout to be set for time
     between epochs. For more information, see *Note
     mysql-cluster-ndbd-definition::.  (Bug#31276
     (http://bugs.mysql.com/31276))

   * *Cluster Replication*: Support for a new conflict resolution
     function `NDB$OLD()' has been added for handling simultaneous
     updates in multi-master and circular replication setups. A new
     status variable `Ndb_conflict_fn_old' tracks the number of times
     that updates are prevented from being applied due to this type of
     conflict resolution. See *Note
     mysql-cluster-replication-conflict-resolution::, for more
     information.

   * On MySQL replication slaves having multiple network interfaces, it
     is now possible to set which interface to use for connecting to
     the master. This can be done by using either the `mysqld' startup
     option `--master-bind' or the `MASTER_BIND='INTERFACE'' clause in
     a `CHANGE MASTER' statement.  (Bug#25939
     (http://bugs.mysql.com/25939))

   * Additional checks were implemented to catch unsupported online
     `ALTER TABLE' operations. Currently it is not possible to reorder
     columns or to change the storage engine used for a table via
     online `ALTER TABLE'.

     Some redundant checks made during online creation of indexes were
     removed.

   * A `--bind-address' option has been added to a number of MySQL
     client programs: `mysql', `mysqldump', `mysqladmin',
     `mysqlbinlog', `mysqlcheck', `mysqlimport', and `mysqlshow'. This
     is for use on a computer having multiple network interfaces, and
     allows you to choose which interface is used to connect to the
     MySQL server.

Bugs fixed:

   * *MySQL Cluster*: It was possible in some cases for a node group to
     be `lost' due to missed local checkpoints following a system
     restart.  (Bug#31525 (http://bugs.mysql.com/31525))

   * *MySQL Cluster*: `NDB' tables having names containing
     non-alphanumeric characters (such as ` `$' ') were not discovered
     correctly.  (Bug#31470 (http://bugs.mysql.com/31470))

   * *MySQL Cluster*: A node failure during a local checkpoint could
     lead to a subsequent failure of the cluster during a system
     restart.  (Bug#31257 (http://bugs.mysql.com/31257))

   * *MySQL Cluster*: A cluster restart could sometimes fail due to an
     issue with table IDs.  (Bug#30975 (http://bugs.mysql.com/30975))

   * *MySQL Cluster*: Transaction timeouts were not handled well in some
     circumstances, leading to excessive number of transactions being
     aborted unnecessarily.  (Bug#30379 (http://bugs.mysql.com/30379))

   * *MySQL Cluster*: In some cases, the cluster managment server
     logged entries multiple times following a restart of `mgmd'.
     (Bug#29565 (http://bugs.mysql.com/29565))

   * *MySQL Cluster*: `ndb_mgm `--help' ' did not display any
     information about the `-a' option.  (Bug#29509
     (http://bugs.mysql.com/29509))

   * *MySQL Cluster*: An interpreted program of sufficient size and
     complexity could cause all cluster data nodes to shut down due to
     buffer overruns.  (Bug#29390 (http://bugs.mysql.com/29390))

   * *MySQL Cluster*: The cluster log was formatted inconsistently and
     contained extraneous newline characters.  (Bug#25064
     (http://bugs.mysql.com/25064))

   * A transaction was not aborted following the failure of statement.
     (Bug#31320 (http://bugs.mysql.com/31320))

   * Online `ALTER' operations involving a column whose data type has
     an implicit default value left behind temporary `.FRM' files,
     causing subsequent `DROP DATABASE' statements to fail.  (Bug#31097
     (http://bugs.mysql.com/31097))

   * Errors could sometimes occur during an online `ADD COLUMN' under
     load.  (Bug#31082 (http://bugs.mysql.com/31082))

   * Transactions were committed prematurely when `LOCK TABLE' and `SET
     AUTOCOMMIT=OFF' were used together.  (Bug#30996
     (http://bugs.mysql.com/30996))

   * The `mysqld_safe' script contained a syntax error.  (Bug#30624
     (http://bugs.mysql.com/30624))


File: manual.info,  Node: mysql-cluster-news-5-1-22-ndb-6-3-3,  Next: mysql-cluster-news-5-1-22-ndb-6-3-2,  Prev: mysql-cluster-news-5-1-22-ndb-6-3-4,  Up: mysql-cluster-news-6-3

20.17.1.14 Changes in MySQL Cluster NDB 6.3.3 (5.1.22-ndb-6.3.3) (20 September 2007)
....................................................................................

This is a new Beta development release, fixing recently discovered bugs
in previous MySQL Cluster NDB 6.3 releases.

Obtaining MySQL Cluster NDB 6.3

MySQL Cluster NDB 6.3 releases are source-only releases which you must
compile and install using the instructions found in *Note
installing-source::, and in *Note mysql-cluster-building::. You can
download the GPL source tarball from the MySQL FTP site at
`ftp://ftp.mysql.com/pub/mysql/download/cluster_telco/'.

This Beta release incorporates all bugfixes and changes made in the
previous MySQL Cluster NDB 6.3 release, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.22 (see *Note news-5-1-22::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *MySQL Cluster*: Mapping of `NDB' error codes to MySQL storage
     engine error codes has been improved.  (Bug#28423
     (http://bugs.mysql.com/28423))

   * *Cluster Replication*: A server status variable
     `ndb_conflict_fn_max' now provides a count of the number of times
     that conflict resolution for MySQL Cluster Replication has been
     applied.

     See *Note mysql-cluster-replication-conflict-resolution::, for
     more information.

Bugs fixed:

   * *Partitioning*: *MySQL Cluster*: `EXPLAIN PARTITIONS' reported
     partition usage by queries on `NDB' tables according to the
     standard MySQL hash function than the hash function used in the
     `NDB' storage engine.  (Bug#29550 (http://bugs.mysql.com/29550))

   * *MySQL Cluster*: Attempting to restore a backup made on a cluster
     host using one endian to a machine using the other endian could
     cause the cluster to fail.  (Bug#29674
     (http://bugs.mysql.com/29674))

   * *MySQL Cluster*: The description of the `--print' option provided
     in the output from `ndb_restore `--help' ' was incorrect.
     (Bug#27683 (http://bugs.mysql.com/27683))

   * *MySQL Cluster*: Restoring a backup made on a cluster host using
     one endian to a machine using the other endian failed for `BLOB'
     and `DATETIME' columns.  (Bug#27543 (http://bugs.mysql.com/27543),
     Bug#30024 (http://bugs.mysql.com/30024))

   * Errors could sometimes occur during an online `ADD COLUMN' under
     load.  (Bug#31082 (http://bugs.mysql.com/31082))


File: manual.info,  Node: mysql-cluster-news-5-1-22-ndb-6-3-2,  Next: mysql-cluster-news-5-1-19-ndb-6-3-1,  Prev: mysql-cluster-news-5-1-22-ndb-6-3-3,  Up: mysql-cluster-news-6-3

20.17.1.15 Changes in MySQL Cluster NDB 6.3.2 (5.1.22-ndb-6.3.2) (07 September 2007)
....................................................................................

This is a new Beta development release, fixing recently discovered bugs
in previous MySQL Cluster NDB 6.3 releases.

Obtaining MySQL Cluster NDB 6.3

MySQL Cluster NDB 6.3 releases are source-only releases which you must
compile and install using the instructions found in *Note
installing-source::, and in *Note mysql-cluster-building::. You can
download the GPL source tarball from the MySQL FTP site at
`ftp://ftp.mysql.com/pub/mysql/download/cluster_telco/'.

This Beta release incorporates all bugfixes and changes made in the
previous MySQL Cluster NDB 6.3 release, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.22 (see *Note news-5-1-22::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *MySQL Cluster*: Online `ADD COLUMN', `ADD INDEX', and `DROP
     INDEX' operations can now be performed explicitly for `NDB'
     tables, as well as online renaming of tables and columns for `NDB'
     and `MyISAM' tables -- that is, without copying or locking of the
     affected tables -- using `ALTER ONLINE TABLE'.

     Indexes can also be created and dropped online using `CREATE
     INDEX' and `DROP INDEX', respectively, using the `ONLINE' keyword.

     You can force operations that would otherwise be performed online
     to be done offline using the `OFFLINE' keyword.

     See *Note alter-table::, *Note create-index::, and *Note
     drop-index::, for more information.

   * *MySQL Cluster*: It is now possible to control whether fixed-width
     or variable-width storage is used for a given column of an `NDB'
     table by means of the `COLUMN_FORMAT' specifier as part of the
     column's definition in a `CREATE TABLE' or `ALTER TABLE' statement.

     It is also possible to control whether a given column of an `NDB'
     table is stored in memory or on disk, using the `STORAGE'
     specifier as part of the column's definition in a `CREATE TABLE' or
     `ALTER TABLE' statement.

     For permitted values and other information about `COLUMN_FORMAT'
     and `STORAGE', see *Note create-table::.

   * *MySQL Cluster*: A new cluster management server startup option
     `--bind-address' makes it possible to restrict management client
     connections to `ndb_mgmd' to a single host and port. For more
     information, see *Note mysql-cluster-ndb-mgmd-command-options::.

   * *Cluster Replication*: Multi-way replication failover and recovery
     for `NDB' is facilitated with the introduction of the
     `--ndb-log-orig' option. When `mysqld' is started with this
     option, the originating server ID and epoch of each binlog event
     is recorded in the `mysql.ndb_binlog_index' table, which now
     contains two additional columns `orig_server_id' and `orig_epoch'
     for storing this information. In such cases, a single epoch on a
     slave may be represented by multiple rows in the slave's
     `ndb_binlog_index' table, one for each epoch as it originated from
     a master.

   * *Cluster Replication*: The protocol for handling global
     checkpoints has been changed.  It is now possible to control how
     often the GCI number is updated, and how often global checkpoints
     are written to disk, using the `TimeBetweenEpochs' configuration
     parameter. This improves the reliability and performance of MySQL
     Cluster Replication.

     GCPs handled using the new protocol are sometimes referred to as
     `micro-GCPs'.

     For more information, see ` TimeBetweenEpochs '.

Bugs fixed:

   * *MySQL Cluster*: When an `NDB' event was left behind but the
     corresponding table was later recreated and received a new table
     ID, the event could not be dropped.  (Bug#30877
     (http://bugs.mysql.com/30877))

   * *MySQL Cluster*: An insufficiently descriptive and potentially
     misleading Error 4006 (`Connect failure - out of connection
     objects...') was produced when either of the following two
     conditions occurred:

       1. There were no more transaction records in the transaction
          coordinator

       2. an `Ndb' object in the NDB API was initialized with
          insufficient parallellism

     Separate error messages are now generated for each of these two
     cases.  (Bug#11313 (http://bugs.mysql.com/11313))

   * *Cluster API*: An `Ndb' object in the NDB API was initialized with
     insufficient parallellism.

   * For micro-GCPs, the assignment of `fake' CGI events no longer
     cause buckets to be sent out of order. Now, when assigning a GCI
     to a non-GCI event (that is, creating a pseudo-GCI or `fake' CGI),
     the GCI that is to arrive is always initiated, even if no known
     GCI exists, which could occur in the event of a node failure.
     (Bug#30884 (http://bugs.mysql.com/30884))

   * There were no more transaction records in the transaction
     coordinator


File: manual.info,  Node: mysql-cluster-news-5-1-19-ndb-6-3-1,  Next: mysql-cluster-news-5-1-19-ndb-6-3-0,  Prev: mysql-cluster-news-5-1-22-ndb-6-3-2,  Up: mysql-cluster-news-6-3

20.17.1.16 Changes in MySQL Cluster NDB 6.3.1 (5.1.19-ndb-6.3.1) (04 July 2007)
...............................................................................

This is a new Beta development release, fixing recently discovered bugs
in the previous MySQL Cluster NDB 6.3 release.

Obtaining MySQL Cluster NDB 6.3

MySQL Cluster NDB 6.3 releases are source-only releases which you must
compile and install using the instructions found in *Note
installing-source::, and in *Note mysql-cluster-building::. You can
download the GPL source tarball from the MySQL FTP site at
`ftp://ftp.mysql.com/pub/mysql/download/cluster_telco/'.

This Beta release incorporates all bugfixes and changes made in the
previous MySQL Cluster NDB 6.3 release, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.19 (see *Note news-5-1-19::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Bugs fixed:

   * Batching of transactions was not handled correctly in some cases.
     (Bug#29525 (http://bugs.mysql.com/29525))


File: manual.info,  Node: mysql-cluster-news-5-1-19-ndb-6-3-0,  Prev: mysql-cluster-news-5-1-19-ndb-6-3-1,  Up: mysql-cluster-news-6-3

20.17.1.17 Changes in MySQL Cluster NDB 6.3.0 (5.1.19-ndb-6.3.0) (02 July 2007)
...............................................................................

This is the first development release for MySQL Cluster NDB 6.3, based
on version 6.3 of the `NDBCLUSTER' storage engine.

Obtaining MySQL Cluster NDB 6.3

MySQL Cluster NDB 6.3 releases are source-only releases which you must
compile and install using the instructions found in *Note
installing-source::, and in *Note mysql-cluster-building::. You can
download the GPL source tarball from the MySQL FTP site at
`ftp://ftp.mysql.com/pub/mysql/download/cluster_telco/'.

This Beta release incorporates all bugfixes and feature changes made in
previous MySQL Cluster releases, as well as all bugfixes and feature
changes which were added in mainline MySQL 5.1 through MySQL 5.1.19
(see *Note news-5-1-19::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *MySQL Cluster*: Reporting functionality has been significantly
     enhanced in this release:

        * A new configuration parameter `BackupReportFrequency' now
          makes it possible to cause the management client to provide
          status reports at regular intervals as well as for such
          reports to be written to the cluster log (depending on cluster
          event logging levels). See *Note
          mysql-cluster-ndbd-definition::, for more information about
          this parameter.

        * A new `REPORT' command has been added in the cluster
          management client. `REPORT BackupStatus' allows you to obtain
          a backup status report at any time during a backup. `REPORT
          MemoryUsage' reports the current data memory and index memory
          used by each data node. For more about the `REPORT' command,
          see *Note mysql-cluster-mgm-client-commands::.

        * `ndb_restore' now provides running reports of its progress
          when restoring a backup. In addition, a complete report
          status report on the backup is written to the cluster log.

   * *MySQL Cluster*: A new configuration parameter `ODirect' causes
     `NDB' to attempt using `O_DIRECT' writes for LCP, backups, and redo
     logs, often lowering CPU usage.

   * *Cluster Replication*: This release implements conflict
     resolution, which makes it possible to determine on a per-table
     basis whether or not an update to a given row on the master should
     be applied on the slave. For more information, see *Note
     mysql-cluster-replication-conflict-resolution::.


File: manual.info,  Node: mysql-cluster-news-6-2,  Next: mysql-cluster-news-6-1,  Prev: mysql-cluster-news-6-3,  Up: mysql-cluster-news

20.17.2 Changes in MySQL Cluster NDB 6.2
----------------------------------------

* Menu:

* mysql-cluster-news-5-1-24-ndb-6-2-16::  Changes in MySQL Cluster NDB 6.2.16 (5.1.24-ndb-6.2.16) (Not yet released)
* mysql-cluster-news-5-1-23-ndb-6-2-15::  Changes in MySQL Cluster NDB 6.2.15 (5.1.23-ndb-6.2.15) (22 May 2008)
* mysql-cluster-news-5-1-23-ndb-6-2-14::  Changes in MySQL Cluster NDB 6.2.14 (5.1.23-ndb-6.2.14) (05 March 2008)
* mysql-cluster-news-5-1-23-ndb-6-2-13::  Changes in MySQL Cluster NDB 6.2.13 (5.1.23-ndb-6.2.13) (22 February 2008)
* mysql-cluster-news-5-1-23-ndb-6-2-12::  Changes in MySQL Cluster NDB 6.2.12 (5.1.23-ndb-6.2.12) (12 February 2008)
* mysql-cluster-news-5-1-23-ndb-6-2-11::  Changes in MySQL Cluster NDB 6.2.11 (5.1.23-ndb-6.2.11) (28 January 2008)
* mysql-cluster-news-5-1-23-ndb-6-2-10::  Changes in MySQL Cluster NDB 6.2.10 (5.1.23-ndb-6.2.10) (19 December 2007)
* mysql-cluster-news-5-1-22-ndb-6-2-9::  Changes in MySQL Cluster NDB 6.2.9 (5.1.22-ndb-6.2.9) (22 November 2007)
* mysql-cluster-news-5-1-22-ndb-6-2-8::  Changes in MySQL Cluster NDB 6.2.8 (5.1.22-ndb-6.2.8) (08 November 2007)
* mysql-cluster-news-5-1-22-ndb-6-2-7::  Changes in MySQL Cluster NDB 6.2.7 (5.1.22-ndb-6.2.7) (10 October 2008)
* mysql-cluster-news-5-1-22-ndb-6-2-6::  Changes in MySQL Cluster NDB 6.2.6 (5.1.22-ndb-6.2.6) (20 September 2007)
* mysql-cluster-news-5-1-22-ndb-6-2-5::  Changes in MySQL Cluster NDB 6.2.5 (5.1.22-ndb-6.2.5) (06 September 2007)
* mysql-cluster-news-5-1-19-ndb-6-2-4::  Changes in MySQL Cluster NDB 6.2.4 (5.1.19-ndb-6.2.4) (04 July 2007)
* mysql-cluster-news-5-1-19-ndb-6-2-3::  Changes in MySQL Cluster NDB 6.2.3 (5.1.19-ndb-6.2.3) (02 July 2007)
* mysql-cluster-news-5-1-18-ndb-6-2-2::  Changes in MySQL Cluster NDB 6.2.2 (5.1.18-ndb-6.2.2) (07 May 2007)
* mysql-cluster-news-5-1-18-ndb-6-2-1::  Changes in MySQL Cluster NDB 6.2.1 (5.1.18-ndb-6.2.1) (30 April 2007)
* mysql-cluster-news-5-1-16-ndb-6-2-0::  Changes in MySQL Cluster NDB 6.2.0 (5.1.16-ndb-6.2.0) (03 March 2007)

This section contains change history information for MySQL Cluster
releases based on version 6.2 of the `NDBCLUSTER' storage engine.

For an overview of new features added in MySQL Cluster NDB 6.2, see
*Note mysql-cluster-changes-5-1-ndb-6-2::.


File: manual.info,  Node: mysql-cluster-news-5-1-24-ndb-6-2-16,  Next: mysql-cluster-news-5-1-23-ndb-6-2-15,  Prev: mysql-cluster-news-6-2,  Up: mysql-cluster-news-6-2

20.17.2.1 Changes in MySQL Cluster NDB 6.2.16 (5.1.24-ndb-6.2.16) (Not yet released)
....................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.2 release.

Obtaining MySQL Cluster NDB 6.2

You can download the latest MySQL Cluster NDB 6.2 source code and
binaries for supported platforms from
http://dev.mysql.com/downloads/cluster.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.2 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.24 (see *Note news-5-1-24::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *MySQL Cluster*: Event buffer lag reports are now written to the
     cluster log.  (Bug#37427 (http://bugs.mysql.com/37427))

   * *MySQL Cluster*: Added the `--no-binlog' option for `ndb_restore'.
     When used, this option prevents information being written to SQL
     node binary logs from the restoration of a cluster backup.
     (Bug#30452 (http://bugs.mysql.com/30452))

   * The `ndbd' and `ndb_mgmd' manpages have been reclassified from
     volume 1 to volume 8.  (Bug#34642 (http://bugs.mysql.com/34642))

Bugs fixed:

   * *Disk Data*: *Important Change*: It is no longer possible on
     32-bit systems to issue statements appearing to create Disk Data
     log files or data files greater than 4 GB in size. (Trying to
     create log files or data files larger than 4 GB on 32-bit systems
     led to unrecoverable data node failures; such statements now fail
     with `NDB' error 1515.)  (Bug#29186 (http://bugs.mysql.com/29186))

   * *Cluster API*: *MySQL Cluster*: Changing the system time on data
     nodes could cause MGM API applications to hang and the data nodes
     to crash.  (Bug#35607 (http://bugs.mysql.com/35607))

   * *MySQL Cluster*: In certain rare situations, `ndb_size.pl' could
     fail with the error `Can't use string ("VALUE") as a HASH ref
     while "strict refs" in use'.  (Bug#43022
     (http://bugs.mysql.com/43022))

   * *MySQL Cluster*: Failure of a data node could sometimes cause
     mysqld to crash.  (Bug#37628 (http://bugs.mysql.com/37628))

   * *MySQL Cluster*: If subscription was terminated while a node was
     down, the epoch was not properly acknowledged by that node.
     (Bug#37442 (http://bugs.mysql.com/37442))

   * *MySQL Cluster*: In rare circumstances, a connection followed by a
     disconnection could give rise to a `stale' connection where the
     connection still existed but was not seen by the transporter.
     (Bug#37338 (http://bugs.mysql.com/37338))

   * *MySQL Cluster*: Under some circumstances, a failed `CREATE TABLE'
     could mean that subsequent `CREATE TABLE' statements caused node
     failures.  (Bug#37092 (http://bugs.mysql.com/37092))

   * *MySQL Cluster*: A fail attempt to create an `NDB' table could in
     some cases lead to resource leaks or cluster failures.  (Bug#37072
     (http://bugs.mysql.com/37072))

   * *MySQL Cluster*: Checking of API node connections was not
     efficiently handled.  (Bug#36843 (http://bugs.mysql.com/36843))

   * *MySQL Cluster*: Attempting to delete a non-existent row from a
     table containing a `TEXT' or `BLOB' column within a transaction
     caused the transaction to fail.  (Bug#36756
     (http://bugs.mysql.com/36756)) See also Bug#36851
     (http://bugs.mysql.com/36851)

   * *MySQL Cluster*: Queries against `NDBCLUSTER' tables were cached
     only if `AUTOCOMMIT' was in use.  (Bug#36692
     (http://bugs.mysql.com/36692))

   * *MySQL Cluster*: `SET GLOBAL ndb_extra_logging' caused `mysqld' to
     crash.  (Bug#36547 (http://bugs.mysql.com/36547))

   * *MySQL Cluster*: If the combined total of tables and indexes in
     the cluster was greater than 4096, issuing `START BACKUP' caused
     data nodes to fail.  (Bug#36044 (http://bugs.mysql.com/36044))

   * *MySQL Cluster*: When more than one SQL node connected to the
     cluster at the same time, creation of the `mysql.ndb_schema' table
     failed on one of them with an explicit `Table exists' error, which
     was not necessary.  (Bug#35943 (http://bugs.mysql.com/35943))

   * *MySQL Cluster*: `mysqld' failed to start after running
     `mysql_upgrade'.  (Bug#35708 (http://bugs.mysql.com/35708))

   * *MySQL Cluster*: If an error occured while executing a statement
     involving a `BLOB' or `TEXT' column of an `NDB' table, a memory
     leak could result.  (Bug#35593 (http://bugs.mysql.com/35593))

   * *MySQL Cluster*: It was not possible to determine the value used
     for the `--ndb-cluster-connection-pool' option in the `mysql'
     client. Now this value is reported as a system status variable.
     (Bug#35573 (http://bugs.mysql.com/35573))

   * *MySQL Cluster*: The `ndb_waiter' utility wrongly calculated
     timeouts.  (Bug#35435 (http://bugs.mysql.com/35435))

   * *MySQL Cluster*: Where column values to be compared in a query
     were of the `VARCHAR' or `VARBINARY' types, `NDBCLUSTER' passed a
     value padded to the full size of the column, which caused
     unnecessary data to be sent to the data nodes. This also had the
     effect of wasting CPU and network bandwidth, and causing condition
     pushdown to be disabled where it could (and should) otherwise have
     been applied.  (Bug#35393 (http://bugs.mysql.com/35393))

   * *MySQL Cluster*: `ndb_restore' incorrectly handled some datatypes
     when applying log files from backups.  (Bug#35343
     (http://bugs.mysql.com/35343))

   * *MySQL Cluster*: In some circumstances, a stopped data node was
     handled incorrectly, leading to redo log space being exhausted
     following an initial restart of the node, or an initial or partial
     restart of the cluster (the wrong CGI might be used in such
     cases). This could happen, for example, when a node was stopped
     following the creation of a new table, but before a new LCP could
     be executed.  (Bug#35241 (http://bugs.mysql.com/35241))

   * *MySQL Cluster*: `SELECT ... LIKE ...' queries yielded incorrect
     results when used on `NDB' tables. As part of this fix, condition
     pushdown of such queries has been disabled; re-enabling it is
     expected to be done as part of a later, permanent fix for this
     issue.  (Bug#35185 (http://bugs.mysql.com/35185))

   * *MySQL Cluster*: `ndb_mgmd' reported errors to `STDOUT' rather
     than to `STDERR'.  (Bug#35169 (http://bugs.mysql.com/35169))

   * *MySQL Cluster*: Nested multi-range reads failed when the second
     multi-range read released the first read's unprocessed operations,
     sometimes leading to a SQL node crash.  (Bug#35137
     (http://bugs.mysql.com/35137))

   * *MySQL Cluster*: In some situations, a problem with synchronizing
     checkpoints between nodes could cause a system restart or a node
     restart to fail with `Error 630 during restore of TX'.  (Bug#34756
     (http://bugs.mysql.com/34756))

   * *MySQL Cluster*: When a secondary index on a `DECIMAL' column was
     used to retrieve data from an `NDB' table, no results were
     returned even if the target table had a matched value in the
     column that was defined with the secondary index.  (Bug#34515
     (http://bugs.mysql.com/34515))

   * *MySQL Cluster*: An `UPDATE' on an `NDB' table that set a new
     value for a unique key column could cause subsequent queries to
     fail.  (Bug#34208 (http://bugs.mysql.com/34208))

   * *MySQL Cluster*: If a data node in one node group was placed in
     the `not started' state (using `NODE_ID RESTART -n'), it was not
     possible to stop a data node in a different node group.
     (Bug#34201 (http://bugs.mysql.com/34201))

   * *MySQL Cluster*: When configured with `NDB' support, MySQL failed
     to compile on 64bit FreeBSD systems.  (Bug#34046
     (http://bugs.mysql.com/34046))

   * *MySQL Cluster*: Numerous `NDBCLUSTER' test failures occurred in
     builds compiled using `icc' on IA64 platforms.  (Bug#31239
     (http://bugs.mysql.com/31239))

   * *MySQL Cluster*: `CREATE TABLE' and `ALTER TABLE' statements using
     `ENGINE=NDB' or `ENGINE=NDBCLUSTER' caused `mysqld' to fail on
     Solaris 10 for x86 platforms.  (Bug#19911
     (http://bugs.mysql.com/19911))

   * *MySQL Cluster*: If an API node disconnected and then reconnected
     during Start Phase 8, then the connection could be `blocked' --
     that is, the `QMGR' kernel block failed to detect that the API
     node was in fact connected to the cluster, causing issues with the
     `NDB' Subscription Manager (`SUMA').

   * *MySQL Cluster*: `NDB' error 1427 (`Api node died, when
     SUB_START_REQ reached node') was incorrectly classified as a
     schema error rather than a temporary error.

   * *MySQL Cluster*: When dropping a table failed for any reason (such
     as when in single user mode) then the corresponding `.ndb' file
     was still removed.

   * *Replication*: When flushing tables, there was a slight chance
     that the flush occurred between the processing of one table map
     event and the next. Since the tables were opened one by one,
     subsequent locking of tables would cause the slave to crash. This
     problem was observed when replicating `NDBCLUSTER' or `InnoDB'
     tables, when executing multi-table updates, and when a trigger or
     a stored routine performed an (additional) insert on a table so
     that two tables were effectively being inserted into in the same
     statement.  (Bug#36197 (http://bugs.mysql.com/36197))

   * *Cluster Replication*: Performing `SELECT ... FROM
     mysql.ndb_apply_status' before the `mysqld' process had connected
     to the cluster failed, and caused this table never to be created.
     (Bug#36123 (http://bugs.mysql.com/36123))

   * *Cluster Replication*: In some cases, when updating only one or
     some columns in a table, the complete row was written to the
     binary log instead of only the updated column or columns, even when
     `ndb_log_updated_only' was set to 1.  (Bug#35208
     (http://bugs.mysql.com/35208))

   * *Cluster API*: Creating a table on an SQL node, then starting an
     NDB API application that listened for events from this table, then
     dropping the table from an SQL node, prevented data node restarts.
     (Bug#37279 (http://bugs.mysql.com/37279))

   * *Cluster API*: When some operations succeeded and some failed
     following a call to `NdbTransaction::execute(Commit,
     AO_IgnoreOnError)', a race condition could cause spurious
     occurrences of NDB API Error 4011 (`Internal error').  (Bug#37158
     (http://bugs.mysql.com/37158))

   * *Cluster API*: Ordered index scans were not pruned correctly where
     a partitioning key was specified with an EQ-bound.  (Bug#36950
     (http://bugs.mysql.com/36950))

   * *Cluster API*: When an insert operation involving `BLOB' data was
     attempted on a row which already existed, no duplicate key error
     was correctly reported and the transaction is incorrectly aborted.
     In some cases, the existing row could also become corrupted.
     (Bug#36851 (http://bugs.mysql.com/36851)) See also Bug#26756
     (http://bugs.mysql.com/26756)

   * *Cluster API*: `NdbApi.hpp' depended on `ndb_global.h', which was
     not actually installed, causing the compilation of programs that
     used `NdbApi.hpp' to fail.  (Bug#35853
     (http://bugs.mysql.com/35853))

   * *Cluster API*: Attempting to pass a nonexistent column name to the
     `equal()' and `setValue()' methods of `NdbOperation' caused NDB API
     applications to crash. Now the column name is checked, and an
     error is returned in the event that the column is not found.
     (Bug#33747 (http://bugs.mysql.com/33747))

   * *Cluster API*: A buffer overrun in `NdbBlob::setValue()' caused
     erroneous results on Mac OS X.  (Bug#31284
     (http://bugs.mysql.com/31284))

   * *Cluster API*: Relocation errors were encountered when trying to
     compile NDB API applications on a number of platforms, including
     64-bit Linux. As a result, `libmysys', `libmystrings', and
     `libdbug' have been changed from normal libraries to `noinst'
     `libtool' helper libraries. They are no longer installed as
     separate libraries; instead, all necessary symbols from these are
     added directly to `libndbclient'. This means that NDB API programs
     now need to be linked only using `-lndbclient'.  (Bug#29791
     (http://bugs.mysql.com/29791))


File: manual.info,  Node: mysql-cluster-news-5-1-23-ndb-6-2-15,  Next: mysql-cluster-news-5-1-23-ndb-6-2-14,  Prev: mysql-cluster-news-5-1-24-ndb-6-2-16,  Up: mysql-cluster-news-6-2

20.17.2.2 Changes in MySQL Cluster NDB 6.2.15 (5.1.23-ndb-6.2.15) (22 May 2008)
...............................................................................

This is re-release of MySQL Cluster NDB 6.2.14 providing binaries for
supported platforms. For more information, see *Note
mysql-cluster-news-5-1-23-ndb-6-2-14::.

Obtaining MySQL Cluster NDB 6.2

You can download the latest MySQL Cluster NDB 6.2 source code and
binaries for supported platforms from
http://dev.mysql.com/downloads/cluster.


File: manual.info,  Node: mysql-cluster-news-5-1-23-ndb-6-2-14,  Next: mysql-cluster-news-5-1-23-ndb-6-2-13,  Prev: mysql-cluster-news-5-1-23-ndb-6-2-15,  Up: mysql-cluster-news-6-2

20.17.2.3 Changes in MySQL Cluster NDB 6.2.14 (5.1.23-ndb-6.2.14) (05 March 2008)
.................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.2 release.

Obtaining MySQL Cluster NDB 6.2

You can download the latest MySQL Cluster NDB 6.2 source code and
binaries for supported platforms from
http://dev.mysql.com/downloads/cluster.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.2 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.23 (see *Note news-5-1-23::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *MySQL Cluster*: Added the `MaxBufferedEpochs' data node
     configuration parameter, which controls the maximum number of
     unprocessed epochs by which a subscribing node can lag.
     Subscribers which exceed this number are disconnected and forced
     to reconnect.

     See *Note mysql-cluster-ndbd-definition::, for more information.

   * *Replication*: Introduced the `slave_exec_mode' system variable to
     control whether idempotent or strict mode is used for replication
     conflict resolution. Idempotent mode suppresses duplicate-key,
     no-key-found, and some other errors, and is needed for circular
     replication, multi-master replication, and some other complex
     replication setups when using MySQL Cluster.  Strict mode is the
     default.  (Bug#31609 (http://bugs.mysql.com/31609))

   * *Cluster Replication*: `RESET MASTER' now uses `TRUNCATE' rather
     than `DELETE' to clear the `mysql.ndb_binlog_index' table. This
     improves the performance of the statement and is less likely to
     leave the table in a fragmented state.  (Bug#34356
     (http://bugs.mysql.com/34356))

   * Formerly, when the MySQL server crashed, the generated stack dump
     was numeric and required external tools to properly resolve the
     names of functions. This is not very helpful to users having a
     limited knowledge of debugging techniques. In addition, the
     generated stack trace contained only the names of functions and
     was formatted differently for each platform due to different stack
     layouts.

     Now it is possible to take advantage of newer versions of the GNU
     C Library provide a set of functions to obtain and manipulate
     stack traces from within the program. On systems that use the ELF
     binary format, the stack trace contains important information such
     as the shared object where the call was generated, an offset into
     the function, and the actual return address. Having the function
     name also makes possible the name demangling of C++ functions.

     The library generates meaningful stack traces on the following
     platforms: i386, x86_64, PowerPC, IA64, Alpha, and S390. On other
     platforms, a numeric stack trace is still produced, and the use of
     the `resolve_stack_dump' utility is still required.  (Bug#31891
     (http://bugs.mysql.com/31891))

   * `mysqltest' now has `mkdir' and `rmdir' commands for creating and
     removing directories.  (Bug#31004 (http://bugs.mysql.com/31004))

   * Added the `Uptime_since_flush_status' status variable, which
     indicates the number of seconds since the most recent `FLUSH
     STATUS' statement. (From Jeremy Cole) (Bug#24822
     (http://bugs.mysql.com/24822))

Bugs fixed:

   * *Important Change*: *Replication*: When the master crashed during
     an update on a transactional table while in `AUTOCOMMIT' mode, the
     slave failed. This fix causes every transaction (including
     `AUTOCOMMIT' transactions) to be recorded in the binlog as
     starting with a `BEGIN' and ending with a `COMMIT' or `ROLLBACK'.
     (Bug#26395 (http://bugs.mysql.com/26395))

   * *Replication*: *Important Note*: Network timeouts between the
     master and the slave could result in corruption of the relay log.
     This fix rectifies a long-standing replication issue when using
     unreliable networks, including replication over wide area networks
     such as the Internet. If you experience reliability issues and see
     many `You have an error in your SQL syntax' errors on replication
     slaves, we strongly recommend that you upgrade to a MySQL version
     which includes this fix.  (Bug#26489 (http://bugs.mysql.com/26489))

   * *Replication*: When the Windows version of `mysqlbinlog' read 4.1
     binlogs containing `LOAD DATA INFILE' statements, it output
     backslashes as path separators, causing problems for client
     programs expecting forward slashes. In such cases, it now converts
     `\\' to `/' in directory paths.  (Bug#34355
     (http://bugs.mysql.com/34355))

   * *Replication*: `SHOW SLAVE STATUS' failed when slave I/O was about
     to terminate.  (Bug#34305 (http://bugs.mysql.com/34305))

   * *Replication*: `mysqlbinlog' from a 5.1 or later MySQL
     distribution could not read binary logs generated by a 4.1 server
     when the logs contained `LOAD DATA INFILE' statements.  (Bug#34141
     (http://bugs.mysql.com/34141)) This regression was introduced by
     Bug#32407 (http://bugs.mysql.com/32407)

   * *Replication*: A `CREATE USER', `DROP USER', or `RENAME USER'
     statement that fails on the master, or that is a duplicate of any
     of these statements, is no longer written to the binlog;
     previously, either of these occurrences could cause the slave to
     fail.

     (Bug#33862 (http://bugs.mysql.com/33862)) See also Bug#29749
     (http://bugs.mysql.com/29749)

   * *Replication*: `mysqlbinlog' failed to release all of its memory
     after terminating abnormally.  (Bug#33247
     (http://bugs.mysql.com/33247))

   * *Replication*: The error message generated due to lack of a
     default value for an extra column was not sufficiently informative.
     (Bug#32971 (http://bugs.mysql.com/32971))

   * *Replication*: When a user variable was used inside an `INSERT'
     statement, the corresponding binlog event was not written to the
     binlog correctly.  (Bug#32580 (http://bugs.mysql.com/32580))

   * *Replication*: When using row-based replication, deletes from a
     table with a foreign key constraint failed on the slave.
     (Bug#32468 (http://bugs.mysql.com/32468))

   * *Replication*: SQL statements containing comments using `--'
     syntax were not replayable by `mysqlbinlog', even though such
     statements replicated correctly.  (Bug#32205
     (http://bugs.mysql.com/32205))

   * *Replication*: When using row-based replication from a master
     running MySQL 5.1.21 or earlier to a slave running 5.1.22 or
     later, updates of integer columns failed on the slave with `Error
     in Unknown event: row application failed'.  (Bug#31583
     (http://bugs.mysql.com/31583)) This regression was introduced by
     Bug#21842 (http://bugs.mysql.com/21842)

   * *Replication*: Replicating write, update, or delete events from a
     master running MySQL 5.1.15 or earlier to a slave running 5.1.16 or
     later caused the slave to crash.  (Bug#31581
     (http://bugs.mysql.com/31581))

   * *Replication*: When using row-based replication, the slave stopped
     when attempting to delete non-existent rows from a slave table
     without a primary key. In addition, no error was reported when
     this occurred.  (Bug#31552 (http://bugs.mysql.com/31552))

   * *Replication*: Issuing a `DROP VIEW' statement caused replication
     to fail if the view did not actually exist.  (Bug#30998
     (http://bugs.mysql.com/30998))

   * *Replication*: Setting `server_id' did not update its value for
     the current session.  (Bug#28908 (http://bugs.mysql.com/28908))

   * *Replication*: Some older servers wrote events to the binary log
     using different numbering from what is currently used, even though
     the file format number in the file is the same. Slaves running
     MySQL 5.1.18 and later could not read these binary logs properly.
     Binary logs from these older versions now are recognized and event
     numbers are mapped to the current numbering so that they can be
     interpreted properly.  (Bug#27779 (http://bugs.mysql.com/27779),
     Bug#32434 (http://bugs.mysql.com/32434)) This regression was
     introduced by Bug#22583 (http://bugs.mysql.com/22583)

   * *Cluster Replication*: The `--ndb-wait-connected' option caused the
     server to wait for a partial connection plus an additional 3
     seconds for a complete connection to the cluster. This could lead
     to issues with setting up the binary log.  (Bug#34757
     (http://bugs.mysql.com/34757))

   * *Cluster API*: Closing a scan before it was executed caused the
     application to segfault.  (Bug#36375 (http://bugs.mysql.com/36375))

   * *Cluster API*: Using NDB API applications from older MySQL Cluster
     versions with `libndbclient' from newer ones caused the cluster to
     fail.  (Bug#36124 (http://bugs.mysql.com/36124))

   * *Cluster API*: Scans having no bounds set were handled incorrectly.
     (Bug#35876 (http://bugs.mysql.com/35876))

   * Use of stored functions in the `WHERE' clause for `SHOW OPEN
     TABLES' caused a server crash.  (Bug#34166
     (http://bugs.mysql.com/34166))

   * Large unsigned integers were improperly handled for prepared
     statements, resulting in truncation or conversion to negative
     numbers.  (Bug#33798 (http://bugs.mysql.com/33798))

   * The server crashed when executing a query that had a subquery
     containing an equality X=Y where Y referred to a named select list
     expression from the parent select. The server crashed when trying
     to use the X=Y equality for `ref'-based access.  (Bug#33794
     (http://bugs.mysql.com/33794))

   * The UPDATE statement allowed `NULL' to be assigned to `NOT NULL'
     columns (the default data type value was assigned). An error
     occurs now.  (Bug#33699 (http://bugs.mysql.com/33699))

   * `ORDER BY ... DESC' sorts could produce misordered results.
     (Bug#33697 (http://bugs.mysql.com/33697))

   * The server could crash when `REPEAT' or another control
     instruction was used in conjunction with labels and a `LEAVE'
     instruction.  (Bug#33618 (http://bugs.mysql.com/33618))

   * `SET GLOBAL myisam_max_sort_file_size=DEFAULT' set
     `myisam_max_sort_file_size' to an incorrect value.  (Bug#33382
     (http://bugs.mysql.com/33382)) See also Bug#31177
     (http://bugs.mysql.com/31177)

   * Granting the `UPDATE' privilege on one column of a view caused the
     server to crash.  (Bug#33201 (http://bugs.mysql.com/33201))

   * For `DECIMAL' columns used with the `ROUND(X,D)' or `TRUNCATE(X,D)'
     function with a non-constant value of D, adding an `ORDER BY' for
     the function result produced misordered output.  (Bug#33143
     (http://bugs.mysql.com/33143)) See also Bug#33402
     (http://bugs.mysql.com/33402), Bug#30617
     (http://bugs.mysql.com/30617)

   * The `SHOW ENGINE INNODB STATUS' and `SHOW ENGINE INNODB MUTEX'
     statements incorrectly required the `SUPER' privilege rather than
     the `PROCESS' privilege.  (Bug#32710 (http://bugs.mysql.com/32710))

   * Tables in the `mysql' database that stored the current `sql_mode'
     value as part of stored program definitions were not updated with
     newer mode values (`NO_ENGINE_SUBSTITUTION',
     `PAD_CHAR_TO_FULL_LENGTH'). This causes various problems defining
     stored programs if those modes were included in the current
     `sql_mode' value.  (Bug#32633 (http://bugs.mysql.com/32633))

   * `ROUND(X,D)' or `TRUNCATE(X,D)' for non-constant values of D could
     crash the server if these functions were used in an `ORDER BY'
     that was resolved using `filesort'.  (Bug#30889
     (http://bugs.mysql.com/30889))

   * Resetting the query cache by issuing a `SET GLOBAL
     query_cache_size=0' statement caused the server to crash if it
     concurrently was saving a new result set to the query cache.
     (Bug#30887 (http://bugs.mysql.com/30887))

   * Replication of `LOAD DATA INFILE' could fail when
     `read_buffer_size' was larger than `max_allowed_packet'.
     (Bug#30435 (http://bugs.mysql.com/30435))

   * The `Table_locks_waited' waited variable was not incremented in
     the cases that a lock had to be waited for but the waiting thread
     was killed or the request was aborted.  (Bug#30331
     (http://bugs.mysql.com/30331))

   * The `Com_create_function' status variable was not incremented
     properly.  (Bug#30252 (http://bugs.mysql.com/30252))

   * `mysqld' displayed the `--enable-pstack' option in its help
     message even if MySQL was configured without `--with-pstack'.
     (Bug#29836 (http://bugs.mysql.com/29836))

   * Replication crashed with the `NDB' storage engine when `mysqld'
     was started with `--character-set-server=ucs2'.  (Bug#29562
     (http://bugs.mysql.com/29562))

   * Views were treated as insertable even if some base table columns
     with no default value were omitted from the view definition.
     (This is contrary to the condition for insertability that a view
     must contain all columns in the base table that do not have a
     default value.)  (Bug#29477 (http://bugs.mysql.com/29477))

   * Previously, the parser accepted the ODBC `{ OJ ... LEFT OUTER JOIN
     ...}' syntax for writing left outer joins.  The parser now allows
     `{ OJ ... }' to be used to write other types of joins, such as
     `INNER JOIN' or `RIGHT OUTER JOIN'. This helps with compatibility
     with some third-party applications, but is not official ODBC
     syntax.  (Bug#28317 (http://bugs.mysql.com/28317))

   * The parser rules for the `SHOW PROFILE' statement were revised to
     work with older versions of `bison'.  (Bug#27433
     (http://bugs.mysql.com/27433))

   * `resolveip' failed to produce correct results for hostnames that
     begin with a digit.  (Bug#27427 (http://bugs.mysql.com/27427))

   * `mysqlcheck -A -r' did not correctly identify all tables that
     needed repairing.  (Bug#25347 (http://bugs.mysql.com/25347))

   * `InnoDB' exhibited thread thrashing with more than 50 concurrent
     connections under an update-intensive workload.  (Bug#22868
     (http://bugs.mysql.com/22868))

   * Warnings for deprecated syntax constructs used in stored routines
     make sense to report only when the routine is being created, but
     they were also being reported when the routine was parsed for
     loading into the execution cache. Now they are reported only at
     routine creation time.  (Bug#21801 (http://bugs.mysql.com/21801))

   * `CREATE ... SELECT' did not always set `DEFAULT' column values in
     the new table.  (Bug#21380 (http://bugs.mysql.com/21380))

   * If a `SELECT' calls a stored function in a transaction, and a
     statement within the function fails, that statement should roll
     back. Furthermore, if `ROLLBACK' is executed after that, the entire
     transaction should be rolled back. Before this fix, the failed
     statement did not roll back when it failed (even though it might
     ultimately get rolled back by a `ROLLBACK' later that rolls back
     the entire transaction).  (Bug#12713 (http://bugs.mysql.com/12713))
     See also Bug#34655 (http://bugs.mysql.com/34655)


File: manual.info,  Node: mysql-cluster-news-5-1-23-ndb-6-2-13,  Next: mysql-cluster-news-5-1-23-ndb-6-2-12,  Prev: mysql-cluster-news-5-1-23-ndb-6-2-14,  Up: mysql-cluster-news-6-2

20.17.2.4 Changes in MySQL Cluster NDB 6.2.13 (5.1.23-ndb-6.2.13) (22 February 2008)
....................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.2 release.

Obtaining MySQL Cluster NDB 6.2

You can download the latest MySQL Cluster NDB 6.2 source code and
binaries for supported platforms from
http://dev.mysql.com/downloads/cluster.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.2 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.23 (see *Note news-5-1-23::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Bugs fixed:

   * *MySQL Cluster*: A node failure during an initial node restart
     followed by another node start could cause the master data node to
     fail, because it incorrectly gave the node permission to start
     even if the invalidated node's LCP was still running.  (Bug#34702
     (http://bugs.mysql.com/34702))


File: manual.info,  Node: mysql-cluster-news-5-1-23-ndb-6-2-12,  Next: mysql-cluster-news-5-1-23-ndb-6-2-11,  Prev: mysql-cluster-news-5-1-23-ndb-6-2-13,  Up: mysql-cluster-news-6-2

20.17.2.5 Changes in MySQL Cluster NDB 6.2.12 (5.1.23-ndb-6.2.12) (12 February 2008)
....................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.2 release.

Obtaining MySQL Cluster NDB 6.2

You can download the latest MySQL Cluster NDB 6.2 source code and
binaries for supported platforms from
http://dev.mysql.com/downloads/cluster.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.2 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.23 (see *Note news-5-1-23::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * Beginning with this version, MySQL Cluster NDB 6.3.X releases once
     again include the `InnoDB' storage engine. In order to enable
     `InnoDB', you must configure the build using `--with-innodb'.

Bugs fixed:

   * *MySQL Cluster*: Upgrades of a cluster using while a `DataMemory'
     setting in excess of 16 GB caused data nodes to fail.  (Bug#34378
     (http://bugs.mysql.com/34378))

   * *MySQL Cluster*: Performing many SQL statements on `NDB' tables
     while in `AUTOCOMMIT' mode caused a memory leak in `mysqld'.
     (Bug#34275 (http://bugs.mysql.com/34275))

   * *MySQL Cluster*: In certain rare circumstances, a race condition
     could occur between an aborted insert and a delete leading a data
     node crash.  (Bug#34260 (http://bugs.mysql.com/34260))

   * *MySQL Cluster*: Multi-table updates using ordered indexes during
     handling of node failures could cause other data nodes to fail.
     (Bug#34216 (http://bugs.mysql.com/34216))

   * *MySQL Cluster*: When configured with `NDB' support, MySQL failed
     to compile using `gcc' 4.3 on 64bit FreeBSD systems.  (Bug#34169
     (http://bugs.mysql.com/34169))

   * *MySQL Cluster*: The failure of a DDL statement could sometimes
     lead to node failures when attempting to execute subsequent DDL
     statements.  (Bug#34160 (http://bugs.mysql.com/34160))

   * *MySQL Cluster*: Extremely long `SELECT' statements (where the
     text of the statement was in excess of 50000 characters) against
     `NDB' tables returned empty results.  (Bug#34107
     (http://bugs.mysql.com/34107))

   * *MySQL Cluster*: Statements executing multiple inserts performed
     poorly on `NDB' tables having `AUTO_INCREMENT' columns.
     (Bug#33534 (http://bugs.mysql.com/33534))

   * *MySQL Cluster*: The `ndb_waiter' utility polled `ndb_mgmd'
     excessively when obtaining the status of cluster data nodes.
     (Bug#32025 (http://bugs.mysql.com/32025)) See also Bug#32023
     (http://bugs.mysql.com/32023)

   * *MySQL Cluster*: Transaction atomicity was sometimes not preserved
     between reads and inserts under high loads.  (Bug#31477
     (http://bugs.mysql.com/31477))

   * *MySQL Cluster*: Having tables with a great many columns could
     cause Cluster backups to fail.  (Bug#30172
     (http://bugs.mysql.com/30172))

   * *Cluster Replication*: *Disk Data*: Statements violating unique
     keys on Disk Data tables (such as attempting to insert `NULL' into
     a `NOT NULL' column) could cause data nodes to fail. When the
     statement was executed from the binlog, this could also result in
     failure of the slave cluster.  (Bug#34118
     (http://bugs.mysql.com/34118))

   * *Disk Data*: Updating in-memory columns of one or more rows of
     Disk Data table, followed by deletion of these rows and
     re-insertion of them, caused data node failures.  (Bug#33619
     (http://bugs.mysql.com/33619))

   * *Cluster Replication*: Setting `--replicate-ignore-db=mysql'
     caused the `mysql.ndb_apply_status' table not to be replicated,
     breaking Cluster Replication.  (Bug#28170
     (http://bugs.mysql.com/28170))


File: manual.info,  Node: mysql-cluster-news-5-1-23-ndb-6-2-11,  Next: mysql-cluster-news-5-1-23-ndb-6-2-10,  Prev: mysql-cluster-news-5-1-23-ndb-6-2-12,  Up: mysql-cluster-news-6-2

20.17.2.6 Changes in MySQL Cluster NDB 6.2.11 (5.1.23-ndb-6.2.11) (28 January 2008)
...................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.2 release.

Obtaining MySQL Cluster NDB 6.2

You can download the latest MySQL Cluster NDB 6.2 source code and
binaries for supported platforms from
http://dev.mysql.com/downloads/cluster.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.2 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.23 (see *Note news-5-1-23::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *Cluster API*: *Important Change*: Because
     `NDB_LE_MemoryUsage.page_size_kb' shows memory page sizes in bytes
     rather than kilobytes, it has been renamed to `page_size_bytes'.
     The name `page_size_kb' is now deprecated and thus subject to
     removal in a future release, although it currently remains
     supported for reasons of backward compatibility. See The
     `Ndb_logevent_type' Type
     (http://dev.mysql.com/doc/ndbapi/en/ndb-logevent-type.html), for
     more information about `NDB_LE_MemoryUsage'.  (Bug#30271
     (http://bugs.mysql.com/30271))

Bugs fixed:

   * *MySQL Cluster*: High numbers of insert operations, delete
     operations, or both could cause `NDB' error 899 (`Rowid already
     allocated') to occur unnecessarily.  (Bug#34033
     (http://bugs.mysql.com/34033))

   * *MySQL Cluster*: A periodic failure to flush the send buffer by the
     `NDB' TCP transporter could cause a unnecessary delay of 10 ms
     between operations.  (Bug#34005 (http://bugs.mysql.com/34005))

   * *MySQL Cluster*: A race condition could occur (very rarely) when
     the release of a GCI was followed by a data node failure.
     (Bug#33793 (http://bugs.mysql.com/33793))

   * *MySQL Cluster*: Some tuple scans caused the wrong memory page to
     be accessed, leading to invalid results. This issue could affect
     both in-memory and Disk Data tables.  (Bug#33739
     (http://bugs.mysql.com/33739))

   * *MySQL Cluster*: The server failed to reject properly the creation
     of an `NDB' table having an unindexed `AUTO_INCREMENT' column.
     (Bug#30417 (http://bugs.mysql.com/30417))

   * *MySQL Cluster*: Issuing an `INSERT ... ON DUPLICATE KEY UPDATE'
     concurrently with or following a `TRUNCATE' statement on an `NDB'
     table failed with `NDB' error 4350 `Transaction already aborted'.
     (Bug#29851 (http://bugs.mysql.com/29851))

   * *MySQL Cluster*: The Cluster backup process could not detect when
     there was no more disk space and instead continued to run until
     killed manually. Now the backup fails with an appropriate error
     when disk space is exhausted.  (Bug#28647
     (http://bugs.mysql.com/28647))

   * *MySQL Cluster*: It was possible in `config.ini' to define cluster
     nodes having node IDs greater than the maximum allowed value.
     (Bug#28298 (http://bugs.mysql.com/28298))

   * *Cluster Replication*: `ndb_restore -e' restored excessively large
     values to the `ndb_apply_status' table's `epoch' column when
     restoring to a MySQL Cluster version supporting Micro-GCPs from an
     older version that did not support these.

     A workaround when restoring to MySQL Cluster releases supporting
     micro-GCPs previous to MySQL Cluster NDB 6.3.8 is to perform a
     32-bit shift on the `epoch' column values to reduce them to their
     proper size.  (Bug#33406 (http://bugs.mysql.com/33406))

   * *Cluster API*: Transactions containing inserts or reads would hang
     during `NdbTransaction::execute()' calls made from NDB API
     applications built against a MySQL Cluster version that did not
     support micro-GCPs accessing a later version that supported
     micro-GCPs. This issue was observed while upgrading from MySQL
     Cluster NDB 6.1.23 to MySQL Cluster NDB 6.2.10 when the API
     application built against the earlier version attempted to access
     a data node already running the later version, even after
     disabling micro-GCPs by setting `TimeBetweenEpochs' equal to 0.
     (Bug#33895 (http://bugs.mysql.com/33895))

   * *Cluster API*: When reading a `BIT(64)' value using
     `NdbOperation:getValue()', 12 bytes were written to the buffer
     rather than the expected 8 bytes.  (Bug#33750
     (http://bugs.mysql.com/33750))


File: manual.info,  Node: mysql-cluster-news-5-1-23-ndb-6-2-10,  Next: mysql-cluster-news-5-1-22-ndb-6-2-9,  Prev: mysql-cluster-news-5-1-23-ndb-6-2-11,  Up: mysql-cluster-news-6-2

20.17.2.7 Changes in MySQL Cluster NDB 6.2.10 (5.1.23-ndb-6.2.10) (19 December 2007)
....................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.2 release.

Obtaining MySQL Cluster NDB 6.2

You can download the latest MySQL Cluster NDB 6.2 source code and
binaries for supported platforms from
http://dev.mysql.com/downloads/cluster.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.2 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.23 (see *Note news-5-1-23::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Bugs fixed:

   * *Partitioning*: *MySQL Cluster*: When partition pruning on an
     `NDB' table resulted in an ordered index scan spanning only one
     partition, any descending flag for the scan was wrongly discarded,
     causing `ORDER BY DESC' to be treated as `ORDER BY ASC', `MAX()'
     to be handled incorrectly, and similar problems.  (Bug#33061
     (http://bugs.mysql.com/33061))

   * *MySQL Cluster*: When all data and SQL nodes in the cluster were
     shut down abnormally (that is, other than by using `STOP' in the
     cluster management client), `ndb_mgm' used excessive amounts of
     CPU.  (Bug#33237 (http://bugs.mysql.com/33237))

   * *MySQL Cluster*: When using micro-GCPs, if a node failed while
     preparing for a global checkpoint, the master node would use the
     wrong GCI.  (Bug#32922 (http://bugs.mysql.com/32922))

   * *MySQL Cluster*: Under some conditions, performing an `ALTER
     TABLE' on an `NDBCLUSTER' table failed with a `Table is full'
     error, even when only 25% of `DataMemory' was in use and the
     result should have been a table using less memory (for example,
     changing a `VARCHAR(100)' column to `VARCHAR(80)').  (Bug#32670
     (http://bugs.mysql.com/32670))


File: manual.info,  Node: mysql-cluster-news-5-1-22-ndb-6-2-9,  Next: mysql-cluster-news-5-1-22-ndb-6-2-8,  Prev: mysql-cluster-news-5-1-23-ndb-6-2-10,  Up: mysql-cluster-news-6-2

20.17.2.8 Changes in MySQL Cluster NDB 6.2.9 (5.1.22-ndb-6.2.9) (22 November 2007)
..................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.2 release.

Obtaining MySQL Cluster NDB 6.2

You can download the latest MySQL Cluster NDB 6.2 source code and
binaries for supported platforms from
http://dev.mysql.com/downloads/cluster.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.2 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.22 (see *Note news-5-1-22::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *MySQL Cluster*: Added the `ndb_mgm' client command `DUMP 8011',
     which dumps all subscribers to the cluster log. See `DUMP 8011'
     (http://dev.mysql.com/doc/ndbapi/en/ndb-internals-dump-command-8011.html),
     for more information.

Bugs fixed:

   * *MySQL Cluster*: A local checkpoint could sometimes be started
     before the previous LCP was restorable from a global checkpoint.
     (Bug#32519 (http://bugs.mysql.com/32519))

   * *MySQL Cluster*: High numbers of API nodes on a slow or congested
     network could cause connection negotiation to time out
     prematurely, leading to the following issues:

        * Excessive retries

        * Excessive CPU usage

        * Partially connected API nodes

     (Bug#32359 (http://bugs.mysql.com/32359))

   * *MySQL Cluster*: The failure of a master node could lead to
     subsequent failures in local checkpointing.  (Bug#32160
     (http://bugs.mysql.com/32160))

   * *MySQL Cluster*: Adding a new `TINYTEXT' column to an `NDB' table
     which used `COLUMN_FORMAT = DYNAMIC', and when binary logging was
     enabled, caused all cluster `mysqld' processes to crash.
     (Bug#30213 (http://bugs.mysql.com/30213))

   * *MySQL Cluster*: After adding a new column of one of the `TEXT' or
     `BLOB' types to an `NDB' table which used `COLUMN_FORMAT =
     DYNAMIC', it was no longer possible to access or drop the table
     using SQL.  (Bug#30205 (http://bugs.mysql.com/30205))

   * *MySQL Cluster*: A restart of the cluster failed when more than 1
     REDO phase was in use.  (Bug#22696 (http://bugs.mysql.com/22696))

   * *Cluster Replication*: Under certain conditions, the slave stopped
     processing relay logs. This resulted in the logs never being
     cleared and the slave eventually running out of disk space.
     (Bug#31958 (http://bugs.mysql.com/31958))

   * *Cluster Replication*: Where a table being replicated had a `TEXT'
     or `BLOB' column, an `UPDATE' on the master that did not refer
     explicitly to this column in the `WHERE' clause stopped the SQL
     thread on the slave with `Error in Write_rows event: row
     application failed. Got error 4288 'Blob handle for column not
     available' from NDBCLUSTER'.  (Bug#30674
     (http://bugs.mysql.com/30674))


File: manual.info,  Node: mysql-cluster-news-5-1-22-ndb-6-2-8,  Next: mysql-cluster-news-5-1-22-ndb-6-2-7,  Prev: mysql-cluster-news-5-1-22-ndb-6-2-9,  Up: mysql-cluster-news-6-2

20.17.2.9 Changes in MySQL Cluster NDB 6.2.8 (5.1.22-ndb-6.2.8) (08 November 2007)
..................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.2 release.

Obtaining MySQL Cluster NDB 6.2

You can download the latest MySQL Cluster NDB 6.2 source code and
binaries for supported platforms from
http://dev.mysql.com/downloads/cluster.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.2 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.22 (see *Note news-5-1-22::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *Important Note*: MySQL Cluster NDB 6.2 and 6.3 source archives
     are now available in separate commercial and GPL versions. Due to
     licensing concerns, previous MySQL Cluster NDB 6.2 and 6.3 source
     archives were removed from the FTP site.

Bugs fixed:

   * *MySQL Cluster*: In a cluster running in diskless mode and with
     arbitration disabled, the failure of a data node during an insert
     operation caused other data node to fail.  (Bug#31980
     (http://bugs.mysql.com/31980))

   * *MySQL Cluster*: An insert or update with combined range and
     equality constraints failed when run against an `NDB' table with
     the error `Got unknown error from NDB'. An example of such a
     statement would be `UPDATE t1 SET b = 5 WHERE a IN (7,8) OR a >=
     10;'.  (Bug#31874 (http://bugs.mysql.com/31874))

   * *MySQL Cluster*: An error with an `if' statement in
     `sql/ha_ndbcluster.cc' could potentially lead to an infinite loop
     in case of failure when working with `AUTO_INCREMENT' columns in
     `NDB' tables.  (Bug#31810 (http://bugs.mysql.com/31810))

   * *MySQL Cluster*: The `NDB' storage engine code was not safe for
     strict-alias optimization in `gcc' 4.2.1.  (Bug#31761
     (http://bugs.mysql.com/31761))

   * *MySQL Cluster*: Following an upgrade, `ndb_mgmd' would fail with
     an ArbitrationError.  (Bug#31690 (http://bugs.mysql.com/31690))

   * *MySQL Cluster*: The `NDB' management client command `NODE_ID
     REPORT MEMORY' provided no output when NODE_ID was the node ID of a
     management or API node. Now, when this occurs, the management
     client responds with `Node NODE_ID: is not a data node'.
     (Bug#29485 (http://bugs.mysql.com/29485))

   * *MySQL Cluster*: Performing `DELETE' operations after a data node
     had been shut down could lead to inconsistent data following a
     restart of the node.  (Bug#26450 (http://bugs.mysql.com/26450))

   * *MySQL Cluster*: `UPDATE IGNORE' could sometimes fail on `NDB'
     tables due to the use of unitialized data when checking for
     duplicate keys to be ignored.  (Bug#25817
     (http://bugs.mysql.com/25817))

   * *Cluster Replication*: A node failure during replication could
     lead to buckets out of order; now active subscribers are checked
     for, rather than empty buckets.  (Bug#31701
     (http://bugs.mysql.com/31701))

   * *Cluster Replication*: When the master `mysqld' crashed or was
     restarted, no `LOST_EVENTS' entry was made in the binlog.
     (Bug#31484 (http://bugs.mysql.com/31484)) See also Bug#21494
     (http://bugs.mysql.com/21494)


File: manual.info,  Node: mysql-cluster-news-5-1-22-ndb-6-2-7,  Next: mysql-cluster-news-5-1-22-ndb-6-2-6,  Prev: mysql-cluster-news-5-1-22-ndb-6-2-8,  Up: mysql-cluster-news-6-2

20.17.2.10 Changes in MySQL Cluster NDB 6.2.7 (5.1.22-ndb-6.2.7) (10 October 2008)
..................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.2 release.

Obtaining MySQL Cluster NDB 6.2

You can download the latest MySQL Cluster NDB 6.2 source code and
binaries for supported platforms from
http://dev.mysql.com/downloads/cluster.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.2 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.22 (see *Note news-5-1-22::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *Cluster Replication*: A new configuration parameter
     `TimeBetweenEpochsTimeout' allows a timeout to be set for time
     between epochs. For more information, see *Note
     mysql-cluster-ndbd-definition::.  (Bug#31276
     (http://bugs.mysql.com/31276))

   * Additional checks were implemented to catch unsupported online
     `ALTER TABLE' operations. Currently it is not possible to reorder
     columns or to change the storage engine used for a table via
     online `ALTER TABLE'.

     Some redundant checks made during online creation of indexes were
     removed.

Bugs fixed:

   * *MySQL Cluster*: It was possible in some cases for a node group to
     be `lost' due to missed local checkpoints following a system
     restart.  (Bug#31525 (http://bugs.mysql.com/31525))

   * *MySQL Cluster*: `NDB' tables having names containing
     non-alphanumeric characters (such as ` `$' ') were not discovered
     correctly.  (Bug#31470 (http://bugs.mysql.com/31470))

   * *MySQL Cluster*: A node failure during a local checkpoint could
     lead to a subsequent failure of the cluster during a system
     restart.  (Bug#31257 (http://bugs.mysql.com/31257))

   * *MySQL Cluster*: A cluster restart could sometimes fail due to an
     issue with table IDs.  (Bug#30975 (http://bugs.mysql.com/30975))

   * *MySQL Cluster*: Transaction timeouts were not handled well in some
     circumstances, leading to excessive number of transactions being
     aborted unnecessarily.  (Bug#30379 (http://bugs.mysql.com/30379))

   * *MySQL Cluster*: In some cases, the cluster managment server
     logged entries multiple times following a restart of `mgmd'.
     (Bug#29565 (http://bugs.mysql.com/29565))

   * *MySQL Cluster*: `ndb_mgm `--help' ' did not display any
     information about the `-a' option.  (Bug#29509
     (http://bugs.mysql.com/29509))

   * *MySQL Cluster*: The cluster log was formatted inconsistently and
     contained extraneous newline characters.  (Bug#25064
     (http://bugs.mysql.com/25064))

   * Online `ALTER' operations involving a column whose data type has
     an implicit default value left behind temporary `.FRM' files,
     causing subsequent `DROP DATABASE' statements to fail.  (Bug#31097
     (http://bugs.mysql.com/31097))

   * Transactions were committed prematurely when `LOCK TABLE' and `SET
     AUTOCOMMIT=OFF' were used together.  (Bug#30996
     (http://bugs.mysql.com/30996))

   * The `mysqld_safe' script contained a syntax error.  (Bug#30624
     (http://bugs.mysql.com/30624))


File: manual.info,  Node: mysql-cluster-news-5-1-22-ndb-6-2-6,  Next: mysql-cluster-news-5-1-22-ndb-6-2-5,  Prev: mysql-cluster-news-5-1-22-ndb-6-2-7,  Up: mysql-cluster-news-6-2

20.17.2.11 Changes in MySQL Cluster NDB 6.2.6 (5.1.22-ndb-6.2.6) (20 September 2007)
....................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.2 release.

Obtaining MySQL Cluster NDB 6.2

You can download the latest MySQL Cluster NDB 6.2 source code and
binaries for supported platforms from
http://dev.mysql.com/downloads/cluster.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.2 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.22 (see *Note news-5-1-22::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *MySQL Cluster*: Mapping of `NDB' error codes to MySQL storage
     engine error codes has been improved.  (Bug#28423
     (http://bugs.mysql.com/28423))

Bugs fixed:

   * *Partitioning*: *MySQL Cluster*: `EXPLAIN PARTITIONS' reported
     partition usage by queries on `NDB' tables according to the
     standard MySQL hash function than the hash function used in the
     `NDB' storage engine.  (Bug#29550 (http://bugs.mysql.com/29550))

   * *MySQL Cluster*: When an `NDB' event was left behind but the
     corresponding table was later recreated and received a new table
     ID, the event could not be dropped.  (Bug#30877
     (http://bugs.mysql.com/30877))

   * *MySQL Cluster*: Attempting to restore a backup made on a cluster
     host using one endian to a machine using the other endian could
     cause the cluster to fail.  (Bug#29674
     (http://bugs.mysql.com/29674))

   * *MySQL Cluster*: The description of the `--print' option provided
     in the output from `ndb_restore `--help' ' was incorrect.
     (Bug#27683 (http://bugs.mysql.com/27683))

   * *MySQL Cluster*: Restoring a backup made on a cluster host using
     one endian to a machine using the other endian failed for `BLOB'
     and `DATETIME' columns.  (Bug#27543 (http://bugs.mysql.com/27543),
     Bug#30024 (http://bugs.mysql.com/30024))

   * *MySQL Cluster*: An insufficiently descriptive and potentially
     misleading Error 4006 (`Connect failure - out of connection
     objects...') was produced when either of the following two
     conditions occurred:

       1. There were no more transaction records in the transaction
          coordinator

       2. an `Ndb' object in the NDB API was initialized with
          insufficient parallellism

     Separate error messages are now generated for each of these two
     cases.  (Bug#11313 (http://bugs.mysql.com/11313))

   * *Cluster API*: An `Ndb' object in the NDB API was initialized with
     insufficient parallellism.

   * For micro-GCPs, the assignment of `fake' CGI events no longer
     cause buckets to be sent out of order. Now, when assigning a GCI
     to a non-GCI event (that is, creating a pseudo-GCI or `fake' CGI),
     the GCI that is to arrive is always initiated, even if no known
     GCI exists, which could occur in the event of a node failure.
     (Bug#30884 (http://bugs.mysql.com/30884))

   * There were no more transaction records in the transaction
     coordinator


File: manual.info,  Node: mysql-cluster-news-5-1-22-ndb-6-2-5,  Next: mysql-cluster-news-5-1-19-ndb-6-2-4,  Prev: mysql-cluster-news-5-1-22-ndb-6-2-6,  Up: mysql-cluster-news-6-2

20.17.2.12 Changes in MySQL Cluster NDB 6.2.5 (5.1.22-ndb-6.2.5) (06 September 2007)
....................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.2 release.

Obtaining MySQL Cluster NDB 6.2

You can download the latest MySQL Cluster NDB 6.2 source code and
binaries for supported platforms from
http://dev.mysql.com/downloads/cluster.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.2 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.22 (see *Note news-5-1-22::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *MySQL Cluster*: The following improvements have been made in the
     `ndb_size.pl' utility:

        * The script can now be used with multiple databases; lists of
          databases and tables can also be excluded from analysis.

        * Schema name information has been added to index table
          calculations.

        * The database name is now an optional parameter, the exclusion
          of which causes all databases to be examined.

        * If selecting from `INFORMATION_SCHEMA' fails, the script now
          attempts to fall back to `SHOW TABLES'.

        * A `--real_table_name' option has been added; this designates
          a table to handle unique index size calculations.

        * The report title has been amended to cover cases where more
          than one database is being analyzed.

     Support for a `--socket' option was also added.

     For more information, see *Note mysql-cluster-utilities-ndb-size::.
     (Bug#28683 (http://bugs.mysql.com/28683), Bug#28253
     (http://bugs.mysql.com/28253))

   * *MySQL Cluster*: Online `ADD COLUMN', `ADD INDEX', and `DROP
     INDEX' operations can now be performed explicitly for `NDB'
     tables, as well as online renaming of tables and columns for `NDB'
     and `MyISAM' tables -- that is, without copying or locking of the
     affected tables -- using `ALTER ONLINE TABLE'.

     Indexes can also be created and dropped online using `CREATE
     INDEX' and `DROP INDEX', respectively, using the `ONLINE' keyword.

     You can force operations that would otherwise be performed online
     to be done offline using the `OFFLINE' keyword.

     See *Note alter-table::, *Note create-index::, and *Note
     drop-index::, for more information.

   * *MySQL Cluster*: It is now possible to control whether fixed-width
     or variable-width storage is used for a given column of an `NDB'
     table by means of the `COLUMN_FORMAT' specifier as part of the
     column's definition in a `CREATE TABLE' or `ALTER TABLE' statement.

     It is also possible to control whether a given column of an `NDB'
     table is stored in memory or on disk, using the `STORAGE'
     specifier as part of the column's definition in a `CREATE TABLE' or
     `ALTER TABLE' statement.

     For permitted values and other information about `COLUMN_FORMAT'
     and `STORAGE', see *Note create-table::.

   * *MySQL Cluster*: A new cluster management server startup option
     `--bind-address' makes it possible to restrict management client
     connections to `ndb_mgmd' to a single host and port. For more
     information, see *Note mysql-cluster-ndb-mgmd-command-options::.

   * *Cluster Replication*: The protocol for handling global
     checkpoints has been changed.  It is now possible to control how
     often the GCI number is updated, and how often global checkpoints
     are written to disk, using the `TimeBetweenEpochs' configuration
     parameter. This improves the reliability and performance of MySQL
     Cluster Replication.

     GCPs handled using the new protocol are sometimes referred to as
     `micro-GCPs'.

     For more information, see ` TimeBetweenEpochs '.

Bugs fixed:

   * *MySQL Cluster*: When handling `BLOB' columns, the addition of
     read locks to the lock queue was not handled correctly.
     (Bug#30764 (http://bugs.mysql.com/30764))

   * *MySQL Cluster*: Discovery of `NDB' tables did not work correctly
     with `INFORMATION_SCHEMA'.  (Bug#30667
     (http://bugs.mysql.com/30667))

   * *MySQL Cluster*: A filesystem close operation could fail during a
     node or system restart.  (Bug#30646 (http://bugs.mysql.com/30646))

   * *MySQL Cluster*: Using the `--ndb-cluster-connection-pool' option
     for `mysqld' caused DDL statements to be executed twice.
     (Bug#30598 (http://bugs.mysql.com/30598))

   * *MySQL Cluster*: `ndb_size.pl' failed on tables with `FLOAT'
     columns whose definitions included commas (for example,
     `FLOAT(6,2)').  (Bug#29228 (http://bugs.mysql.com/29228))

   * *MySQL Cluster*: Reads on `BLOB' columns were not locked when they
     needed to be to guarantee consistency.  (Bug#29102
     (http://bugs.mysql.com/29102)) See also Bug#31482
     (http://bugs.mysql.com/31482)

   * *MySQL Cluster*: A query using joins between several large tables
     and requiring unique index lookups failed to complete, eventually
     returning `Uknown Error' after a very long period of time. This
     occurred due to inadequate handling of instances where the
     Transaction Coordinator ran out of `TransactionBufferMemory', when
     the cluster should have returned NDB error code 4012 (`Request
     ndbd time-out').  (Bug#28804 (http://bugs.mysql.com/28804))

   * *MySQL Cluster*: An attempt to perform a `SELECT ... FROM
     INFORMATION_SCHEMA.TABLES' whose result included information about
     `NDB' tables for which the user had no privileges crashed the
     MySQL Server on which the query was performed.  (Bug#26793
     (http://bugs.mysql.com/26793))

   * *Cluster Replication*: Cluster replication did not handle large
     `VARCHAR' columns correctly.  (Bug#29904
     (http://bugs.mysql.com/29904))

   * *Cluster Replication*: An issue with the `mysql.ndb_apply_status'
     table could cause `NDB' schema autodiscovery to fail in certain
     rare circumstances.  (Bug#20872 (http://bugs.mysql.com/20872))

   * *Cluster API*: A call to `CHECK_TIMEDOUT_RET()' in `mgmapi.cpp'
     should have been a call to `DBUG_CHECK_TIMEDOUT_RET()'.
     (Bug#30681 (http://bugs.mysql.com/30681))


File: manual.info,  Node: mysql-cluster-news-5-1-19-ndb-6-2-4,  Next: mysql-cluster-news-5-1-19-ndb-6-2-3,  Prev: mysql-cluster-news-5-1-22-ndb-6-2-5,  Up: mysql-cluster-news-6-2

20.17.2.13 Changes in MySQL Cluster NDB 6.2.4 (5.1.19-ndb-6.2.4) (04 July 2007)
...............................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.2 release.

Obtaining MySQL Cluster NDB 6.2

You can download the latest MySQL Cluster NDB 6.2 source code and
binaries for supported platforms from
http://dev.mysql.com/downloads/cluster.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.2 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.19 (see *Note news-5-1-19::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Bugs fixed:

   * *MySQL Cluster*: When restarting a data node, queries could hang
     during that node's start phase 5, and continue only after the node
     had entered phase 6.  (Bug#29364 (http://bugs.mysql.com/29364))

   * *MySQL Cluster*: Replica redo logs were inconsistently handled
     during a system restart.  (Bug#29354 (http://bugs.mysql.com/29354))

   * *Disk Data*: Performing Disk Data schema operations during a node
     restart could cause forced shutdowns of other data nodes.
     (Bug#29501 (http://bugs.mysql.com/29501))

   * *Disk Data*: Disk data meta-information that existed in `ndbd'
     might not be visible to `mysqld'.  (Bug#28720
     (http://bugs.mysql.com/28720))

   * *Disk Data*: The number of free extents was incorrectly reported
     for some tablespaces.  (Bug#28642 (http://bugs.mysql.com/28642))

   * Batching of transactions was not handled correctly in some cases.
     (Bug#29525 (http://bugs.mysql.com/29525))


File: manual.info,  Node: mysql-cluster-news-5-1-19-ndb-6-2-3,  Next: mysql-cluster-news-5-1-18-ndb-6-2-2,  Prev: mysql-cluster-news-5-1-19-ndb-6-2-4,  Up: mysql-cluster-news-6-2

20.17.2.14 Changes in MySQL Cluster NDB 6.2.3 (5.1.19-ndb-6.2.3) (02 July 2007)
...............................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.2 release.

Obtaining MySQL Cluster NDB 6.2

You can download the latest MySQL Cluster NDB 6.2 source code and
binaries for supported platforms from
http://dev.mysql.com/downloads/cluster.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.2 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.18 (see *Note news-5-1-18::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Bugs fixed:

   * *MySQL Cluster*: When restarting a data node, queries could hang
     during that node's start phase 5, and continue only after the node
     had entered phase 6.  (Bug#29364 (http://bugs.mysql.com/29364))

   * *MySQL Cluster*: Replica redo logs were inconsistently handled
     during a system restart.  (Bug#29354 (http://bugs.mysql.com/29354))

   * *Disk Data*: Performing Disk Data schema operations during a node
     restart could cause forced shutdowns of other data nodes.
     (Bug#29501 (http://bugs.mysql.com/29501))

   * *Disk Data*: Disk data meta-information that existed in `ndbd'
     might not be visible to `mysqld'.  (Bug#28720
     (http://bugs.mysql.com/28720))

   * *Disk Data*: The number of free extents was incorrectly reported
     for some tablespaces.  (Bug#28642 (http://bugs.mysql.com/28642))

   * Batching of transactions was not handled correctly in some cases.
     (Bug#29525 (http://bugs.mysql.com/29525))


File: manual.info,  Node: mysql-cluster-news-5-1-18-ndb-6-2-2,  Next: mysql-cluster-news-5-1-18-ndb-6-2-1,  Prev: mysql-cluster-news-5-1-19-ndb-6-2-3,  Up: mysql-cluster-news-6-2

20.17.2.15 Changes in MySQL Cluster NDB 6.2.2 (5.1.18-ndb-6.2.2) (07 May 2007)
..............................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.2 release.

Obtaining MySQL Cluster NDB 6.2

You can download the latest MySQL Cluster NDB 6.2 source code and
binaries for supported platforms from
http://dev.mysql.com/downloads/cluster.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.2 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.18 (see *Note news-5-1-18::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *MySQL Cluster*: New cluster management client `DUMP' commands
     were added to aid in tracking transactions, scan operations, and
     locks. See `DUMP 2350'
     (http://dev.mysql.com/doc/ndbapi/en/ndb-internals-dump-command-2350.html),
     `DUMP 2352'
     (http://dev.mysql.com/doc/ndbapi/en/ndb-internals-dump-command-2352.html),
     and `DUMP 2550'
     (http://dev.mysql.com/doc/ndbapi/en/ndb-internals-dump-command-2550.html),
     for more information.

   * *MySQL Cluster*: Added the `mysqld' option
     `--ndb-cluster-connection-pool' that allows a single MySQL server
     to use multiple connections to the cluster.  This allows for
     scaling out using multiple MySQL clients per SQL node instead of
     or in addition to using multiple SQL nodes with the cluster.

     For more information about this option, see *Note
     mysql-cluster-options-variables::.


File: manual.info,  Node: mysql-cluster-news-5-1-18-ndb-6-2-1,  Next: mysql-cluster-news-5-1-16-ndb-6-2-0,  Prev: mysql-cluster-news-5-1-18-ndb-6-2-2,  Up: mysql-cluster-news-6-2

20.17.2.16 Changes in MySQL Cluster NDB 6.2.1 (5.1.18-ndb-6.2.1) (30 April 2007)
................................................................................

This is a Beta development release, fixing recently discovered bugs in
the previous MySQL Cluster NDB 6.2 release.

Obtaining MySQL Cluster NDB 6.2

You can download the latest MySQL Cluster NDB 6.2 source code and
binaries for supported platforms from
http://dev.mysql.com/downloads/cluster.

This Beta release incorporates all bugfixes and changes made in the
previous MySQL Cluster NDB 6.2 release, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.18 (see *Note news-5-1-18::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Bugs fixed:

   * *MySQL Cluster*: Multiple operations involving deletes followed by
     reads were not handled correctly.

     *Note*:

     This issue could also affect MySQL Cluster Replication.

     (Bug#28276 (http://bugs.mysql.com/28276))

   * *Cluster API*: Using `NdbBlob::writeData()' to write data in the
     middle of an existing blob value (that is, updating the value)
     could overwrite some data past the end of the data to be changed.
     (Bug#27018 (http://bugs.mysql.com/27018))

   * Incorrect handling of fragmentation in a node takeover during a
     restart could cause stale data to be copied to the starting node,
     leading eventually to failure of the node.  (Bug#27434
     (http://bugs.mysql.com/27434))

   * An incorrect assertion was made when sending a `TCKEYFAILREF' or
     `TCKEYCONF' message to a failed data node.  (Bug#26814
     (http://bugs.mysql.com/26814))


File: manual.info,  Node: mysql-cluster-news-5-1-16-ndb-6-2-0,  Prev: mysql-cluster-news-5-1-18-ndb-6-2-1,  Up: mysql-cluster-news-6-2

20.17.2.17 Changes in MySQL Cluster NDB 6.2.0 (5.1.16-ndb-6.2.0) (03 March 2007)
................................................................................

This is the first MySQL Cluster NDB 6.2 development release, based on
version 6.2 of the `NDBCLUSTER' storage engine.

Obtaining MySQL Cluster NDB 6.2

You can download the latest MySQL Cluster NDB 6.2 source code and
binaries for supported platforms from
http://dev.mysql.com/downloads/cluster.

This Beta release incorporates bugfixes and changes made in previous
MySQL Cluster releases, as well as all bugfixes and feature changes
which were added in mainline MySQL 5.1 through MySQL 5.1.16 (see *Note
news-5-1-16::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *MySQL Cluster*: An `--ndb-wait-connected' option has been added
     for `mysqld', which causes `mysqld' to wait for the specified
     amount of time to connect to the cluster before starting to accept
     MySQL client connections.

   * *Cluster API*: The `Ndb::startTransaction()' method now provides
     an alternative interface for starting a transaction.  See
     `Ndb::startTransaction()'
     (http://dev.mysql.com/doc/ndbapi/en/class-ndb-starttransaction.html),
     for more information.

   * *Cluster API*: Methods were added to the `Ndb_cluster_connection'
     class to faciliate iterating over existing `Ndb' objects. See
     `ndb_cluster_connection::get_next_ndb_object()'
     (http://dev.mysql.com/doc/ndbapi/en/class-ndb-cluster-connection-get-next-ndb-object.html),
     for more information.

   * It is now possible to disable arbitration by setting
     `ArbitrationRank' equal to `0' on all nodes.

   * A new `TcpBind_INADDR_ANY' configuration parameter allows data
     nodes node to bind `INADDR_ANY' instead of a hostname or IP
     address in the `config.ini' file.

   * Memory allocation has been improved on 32-bit architectures that
     enables using close to 3GB for `DataMemory' and `IndexMemory'
     combined.


File: manual.info,  Node: mysql-cluster-news-6-1,  Prev: mysql-cluster-news-6-2,  Up: mysql-cluster-news

20.17.3 Changes in MySQL Cluster NDB 6.1
----------------------------------------

* Menu:

* mysql-cluster-news-5-1-15-ndb-6-1-23::  Changes in MySQL Cluster NDB 6.1.23 (5.1.15-ndb-6.1.23) (20 November 2007)
* mysql-cluster-news-5-1-15-ndb-6-1-22::  Changes in MySQL Cluster NDB 6.1.22 (5.1.15-ndb-6.1.22) (19 October 2007)
* mysql-cluster-news-5-1-15-ndb-6-1-21::  Changes in MySQL Cluster NDB 6.1.21 (5.1.15-ndb-6.1.21) (01 October 2007)
* mysql-cluster-news-5-1-15-ndb-6-1-20::  Changes in MySQL Cluster NDB 6.1.20 (5.1.15-ndb-6.1.20) (14 September 2007)
* mysql-cluster-news-5-1-15-ndb-6-1-19::  Changes in MySQL Cluster NDB 6.1.19 (5.1.15-ndb-6.1.19) (01 August 2007)
* mysql-cluster-news-5-1-15-ndb-6-1-18::  Changes in MySQL Cluster NDB 6.1.18 (5.1.15-ndb-6.1.18) (Not released)
* mysql-cluster-news-5-1-15-ndb-6-1-17::  Changes in MySQL Cluster NDB 6.1.17 (5.1.15-ndb-6.1.17) (03 July 2007)
* mysql-cluster-news-5-1-15-ndb-6-1-16::  Changes in MySQL Cluster NDB 6.1.16 (5.1.15-ndb-6.1.16) (29 June 2007)
* mysql-cluster-news-5-1-15-ndb-6-1-15::  Changes in MySQL Cluster NDB 6.1.15 (5.1.15-ndb-6.1.15) (20 June 2007)
* mysql-cluster-news-5-1-15-ndb-6-1-14::  Changes in MySQL Cluster NDB 6.1.14 (5.1.15-ndb-6.1.14) (19 June 2007)
* mysql-cluster-news-5-1-15-ndb-6-1-13::  Changes in MySQL Cluster NDB 6.1.13 (5.1.15-ndb-6.1.13) (15 June 2007)
* mysql-cluster-news-5-1-15-ndb-6-1-12::  Changes in MySQL Cluster NDB 6.1.12 (5.1.15-ndb-6.1.12) (13 June 2007)
* mysql-cluster-news-5-1-15-ndb-6-1-11::  Changes in MySQL Cluster NDB 6.1.11 (5.1.15-ndb-6.1.11) (06 June 2007)
* mysql-cluster-news-5-1-15-ndb-6-1-10::  Changes in MySQL Cluster NDB 6.1.10 (5.1.15-ndb-6.1.10) (30 May 2007)
* mysql-cluster-news-5-1-15-ndb-6-1-9::  Changes in MySQL Cluster NDB 6.1.9 (5.1.15-ndb-6.1.9) (24 May 2007)
* mysql-cluster-news-5-1-15-ndb-6-1-8::  Changes in MySQL Cluster NDB 6.1.8 (5.1.15-ndb-6.1.8) (05 May 2007)
* mysql-cluster-news-5-1-15-ndb-6-1-7::  Changes in MySQL Cluster NDB 6.1.7 (5.1.15-ndb-6.1.7) (05 May 2007)
* mysql-cluster-news-5-1-15-ndb-6-1-6::  Changes in MySQL Cluster NDB 6.1.6 (5.1.15-ndb-6.1.6) (Not released)
* mysql-cluster-news-5-1-15-ndb-6-1-5::  Changes in MySQL Cluster NDB 6.1.5 (5.1.15-ndb-6.1.5) (15 March 2007)
* mysql-cluster-news-5-1-15-ndb-6-1-4::  Changes in MySQL Cluster NDB 6.1.4 (5.1.15-ndb-6.1.4) (09 March 2007))
* mysql-cluster-news-5-1-15-ndb-6-1-3::  Changes in MySQL Cluster NDB 6.1.3 (5.1.15-ndb-6.1.3) (25 February 2007)
* mysql-cluster-news-5-1-15-ndb-6-1-2::  Changes in MySQL Cluster NDB 6.1.2 (5.1.15-ndb-6.1.2) (07 February 2007)
* mysql-cluster-news-5-1-15-ndb-6-1-1::  Changes in MySQL Cluster NDB 6.1.1 (5.1.15-ndb-6.1.1) (01 February 2007)
* mysql-cluster-news-5-1-14-ndb-6-1-0::  Changes in MySQL Cluster NDB 6.1.0 (5.1.14-ndb-6.1.0) (20 December 2006)

This section contains change history information for MySQL Cluster
releases based on version 6.1 of the `NDBCLUSTER' storage engine.

For an overview of new features added in MySQL Cluster NDB 6.1, see
*Note mysql-cluster-changes-5-1-ndb-6-1::.


File: manual.info,  Node: mysql-cluster-news-5-1-15-ndb-6-1-23,  Next: mysql-cluster-news-5-1-15-ndb-6-1-22,  Prev: mysql-cluster-news-6-1,  Up: mysql-cluster-news-6-1

20.17.3.1 Changes in MySQL Cluster NDB 6.1.23 (5.1.15-ndb-6.1.23) (20 November 2007)
....................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.1 release.

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.1 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.15 (see *Note news-5-1-15::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Bugs fixed:

   * *MySQL Cluster*: The `NDB' storage engine code was not safe for
     strict-alias optimization in `gcc' 4.2.1.  (Bug#31761
     (http://bugs.mysql.com/31761))

   * *Cluster Replication*: Under certain conditions, the slave stopped
     processing relay logs. This resulted in the logs never being
     cleared and the slave eventually running out of disk space.
     (Bug#31958 (http://bugs.mysql.com/31958))


File: manual.info,  Node: mysql-cluster-news-5-1-15-ndb-6-1-22,  Next: mysql-cluster-news-5-1-15-ndb-6-1-21,  Prev: mysql-cluster-news-5-1-15-ndb-6-1-23,  Up: mysql-cluster-news-6-1

20.17.3.2 Changes in MySQL Cluster NDB 6.1.22 (5.1.15-ndb-6.1.22) (19 October 2007)
...................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.1 release.

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.1 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.15 (see *Note news-5-1-15::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Bugs fixed:

   * *MySQL Cluster*: It was possible in some cases for a node group to
     be `lost' due to missed local checkpoints following a system
     restart.  (Bug#31525 (http://bugs.mysql.com/31525))

   * *Cluster Replication*: A node failure during replication could
     lead to buckets out of order; now active subscribers are checked
     for, rather than empty buckets.  (Bug#31701
     (http://bugs.mysql.com/31701))


File: manual.info,  Node: mysql-cluster-news-5-1-15-ndb-6-1-21,  Next: mysql-cluster-news-5-1-15-ndb-6-1-20,  Prev: mysql-cluster-news-5-1-15-ndb-6-1-22,  Up: mysql-cluster-news-6-1

20.17.3.3 Changes in MySQL Cluster NDB 6.1.21 (5.1.15-ndb-6.1.21) (01 October 2007)
...................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.1 release.

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.1 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.15 (see *Note news-5-1-15::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Bugs fixed:

   * *MySQL Cluster*: A node failure during a local checkpoint could
     lead to a subsequent failure of the cluster during a system
     restart.  (Bug#31257 (http://bugs.mysql.com/31257))

   * *MySQL Cluster*: A cluster restart could sometimes fail due to an
     issue with table IDs.  (Bug#30975 (http://bugs.mysql.com/30975))


File: manual.info,  Node: mysql-cluster-news-5-1-15-ndb-6-1-20,  Next: mysql-cluster-news-5-1-15-ndb-6-1-19,  Prev: mysql-cluster-news-5-1-15-ndb-6-1-21,  Up: mysql-cluster-news-6-1

20.17.3.4 Changes in MySQL Cluster NDB 6.1.20 (5.1.15-ndb-6.1.20) (14 September 2007)
.....................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.1 release.

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.1 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.15 (see *Note news-5-1-15::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Bugs fixed:

   * *Cluster Replication*: Incorrect handling of `INSERT' plus
     `DELETE' operations with regard to local checkpoints caused data
     node failures in multi-master replication setups.  (Bug#30914
     (http://bugs.mysql.com/30914))


File: manual.info,  Node: mysql-cluster-news-5-1-15-ndb-6-1-19,  Next: mysql-cluster-news-5-1-15-ndb-6-1-18,  Prev: mysql-cluster-news-5-1-15-ndb-6-1-20,  Up: mysql-cluster-news-6-1

20.17.3.5 Changes in MySQL Cluster NDB 6.1.19 (5.1.15-ndb-6.1.19) (01 August 2007)
..................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.1 release.

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.1 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.15 (see *Note news-5-1-15::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *MySQL Cluster*: Whenever a TCP send buffer is over 80% full,
     temporary error 1218 (`Send Buffers overloaded in NDB kernel') is
     now returned. See SendBufferMemory for more information.

   * An `INFO' event is now sent if the time between global checkpoints
     is excessive, or if `DUMP 7901' is issued in the management client.


File: manual.info,  Node: mysql-cluster-news-5-1-15-ndb-6-1-18,  Next: mysql-cluster-news-5-1-15-ndb-6-1-17,  Prev: mysql-cluster-news-5-1-15-ndb-6-1-19,  Up: mysql-cluster-news-6-1

20.17.3.6 Changes in MySQL Cluster NDB 6.1.18 (5.1.15-ndb-6.1.18) (Not released)
................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.1 release.

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.1 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.15 (see *Note news-5-1-15::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Bugs fixed:

   * *MySQL Cluster*: When restarting a data node, queries could hang
     during that node's start phase 5, and continue only after the node
     had entered phase 6.  (Bug#29364 (http://bugs.mysql.com/29364))

   * *Disk Data*: Disk data meta-information that existed in `ndbd'
     might not be visible to `mysqld'.  (Bug#28720
     (http://bugs.mysql.com/28720))

   * *Disk Data*: The number of free extents was incorrectly reported
     for some tablespaces.  (Bug#28642 (http://bugs.mysql.com/28642))

   * Storage engine error conditions in row-based replication were not
     correctly reported to the user.  (Bug#29570
     (http://bugs.mysql.com/29570))


File: manual.info,  Node: mysql-cluster-news-5-1-15-ndb-6-1-17,  Next: mysql-cluster-news-5-1-15-ndb-6-1-16,  Prev: mysql-cluster-news-5-1-15-ndb-6-1-18,  Up: mysql-cluster-news-6-1

20.17.3.7 Changes in MySQL Cluster NDB 6.1.17 (5.1.15-ndb-6.1.17) (03 July 2007)
................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.1 release.

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.1 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.15 (see *Note news-5-1-15::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *Cluster Replication*: Batching of updates on cluster replication
     slaves, enabled using the `--slave-allow-batching' option for
     `mysqld'.

Bugs fixed:

   * *MySQL Cluster*: Replica redo logs were inconsistently handled
     during a system restart.  (Bug#29354 (http://bugs.mysql.com/29354))


File: manual.info,  Node: mysql-cluster-news-5-1-15-ndb-6-1-16,  Next: mysql-cluster-news-5-1-15-ndb-6-1-15,  Prev: mysql-cluster-news-5-1-15-ndb-6-1-17,  Up: mysql-cluster-news-6-1

20.17.3.8 Changes in MySQL Cluster NDB 6.1.16 (5.1.15-ndb-6.1.16) (29 June 2007)
................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.1 release.

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.1 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.15 (see *Note news-5-1-15::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Bugs fixed:

   * *MySQL Cluster*: When a node failed to respond to a `COPY_GCI'
     signal as part of a global checkpoint, the master node was killed
     instead of the node that actually failed.  (Bug#29331
     (http://bugs.mysql.com/29331))

   * *MySQL Cluster*: An invalid comparison made during `REDO'
     validation that could lead to an `Error while reading REDO log'
     condition.  (Bug#29118 (http://bugs.mysql.com/29118))

   * *MySQL Cluster*: The wrong data pages were sometimes invalidated
     following a global checkpoint.  (Bug#29067
     (http://bugs.mysql.com/29067))

   * *MySQL Cluster*: If at least 2 files were involved in `REDO'
     invalidation, then file 0 of page 0 was not updated and so pointed
     to an invalid part of the redo log.  (Bug#29057
     (http://bugs.mysql.com/29057))

   * *Disk Data*: When dropping a page, the stack's bottom entry could
     sometime be left `cold' rather than `hot', violating the rules for
     stack pruning.  (Bug#29176 (http://bugs.mysql.com/29176))


File: manual.info,  Node: mysql-cluster-news-5-1-15-ndb-6-1-15,  Next: mysql-cluster-news-5-1-15-ndb-6-1-14,  Prev: mysql-cluster-news-5-1-15-ndb-6-1-16,  Up: mysql-cluster-news-6-1

20.17.3.9 Changes in MySQL Cluster NDB 6.1.15 (5.1.15-ndb-6.1.15) (20 June 2007)
................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.1 release.

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.1 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.15 (see *Note news-5-1-15::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Bugs fixed:

   * *MySQL Cluster*: Memory corruption could occur due to a problem in
     the `DBTUP' kernel block.  (Bug#29229
     (http://bugs.mysql.com/29229))


File: manual.info,  Node: mysql-cluster-news-5-1-15-ndb-6-1-14,  Next: mysql-cluster-news-5-1-15-ndb-6-1-13,  Prev: mysql-cluster-news-5-1-15-ndb-6-1-15,  Up: mysql-cluster-news-6-1

20.17.3.10 Changes in MySQL Cluster NDB 6.1.14 (5.1.15-ndb-6.1.14) (19 June 2007)
.................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.1 release.

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.1 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.15 (see *Note news-5-1-15::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Bugs fixed:

   * *MySQL Cluster*: In the event that two data nodes in the same node
     group and participating in a GCP crashed before they had written
     their respective `P0.sysfile' files, `QMGR' could refuse to start,
     issuing an invalid `Insufficient nodes for restart' error instead.
     (Bug#29167 (http://bugs.mysql.com/29167))


File: manual.info,  Node: mysql-cluster-news-5-1-15-ndb-6-1-13,  Next: mysql-cluster-news-5-1-15-ndb-6-1-12,  Prev: mysql-cluster-news-5-1-15-ndb-6-1-14,  Up: mysql-cluster-news-6-1

20.17.3.11 Changes in MySQL Cluster NDB 6.1.13 (5.1.15-ndb-6.1.13) (15 June 2007)
.................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.1 release.

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.1 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.15 (see *Note news-5-1-15::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * Read ahead was implemented for backups of Disk Data tables,
     resulting in a 10 to 15% increase in backup speed of Disk Data
     tables.  (Bug#29099 (http://bugs.mysql.com/29099))

Bugs fixed:

   * *Cluster API*: `NdbApi.hpp' depended on `ndb_global.h', which was
     not actually installed, causing the compilation of programs that
     used `NdbApi.hpp' to fail.  (Bug#35853
     (http://bugs.mysql.com/35853))


File: manual.info,  Node: mysql-cluster-news-5-1-15-ndb-6-1-12,  Next: mysql-cluster-news-5-1-15-ndb-6-1-11,  Prev: mysql-cluster-news-5-1-15-ndb-6-1-13,  Up: mysql-cluster-news-6-1

20.17.3.12 Changes in MySQL Cluster NDB 6.1.12 (5.1.15-ndb-6.1.12) (13 June 2007)
.................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.1 release.

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.1 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.15 (see *Note news-5-1-15::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *MySQL Cluster*: New cluster management client `DUMP' commands
     were added to aid in tracking transactions, scan operations, and
     locks. See `DUMP 2350'
     (http://dev.mysql.com/doc/ndbapi/en/ndb-internals-dump-command-2350.html),
     `DUMP 2352'
     (http://dev.mysql.com/doc/ndbapi/en/ndb-internals-dump-command-2352.html),
     and `DUMP 2550'
     (http://dev.mysql.com/doc/ndbapi/en/ndb-internals-dump-command-2550.html).

   * Backup dump output was extended to provide more information.

Bugs fixed:

   * *MySQL Cluster*: It is now possible to set the maximum size of the
     allocation unit for table memory using the `MaxAllocate'
     configuration parameter.  (Bug#29044 (http://bugs.mysql.com/29044))


File: manual.info,  Node: mysql-cluster-news-5-1-15-ndb-6-1-11,  Next: mysql-cluster-news-5-1-15-ndb-6-1-10,  Prev: mysql-cluster-news-5-1-15-ndb-6-1-12,  Up: mysql-cluster-news-6-1

20.17.3.13 Changes in MySQL Cluster NDB 6.1.11 (5.1.15-ndb-6.1.11) (06 June 2007)
.................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.1 release.

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.1 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.15 (see *Note news-5-1-15::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *Important Change*: *MySQL Cluster*: The
     `TimeBetweenWatchdogCheckInitial' configuration parameter was
     added to allow setting of a separate watchdog timeout for memory
     allocation during startup of the data nodes. See *Note
     mysql-cluster-ndbd-definition::, for more information.  (Bug#28899
     (http://bugs.mysql.com/28899))

   * *MySQL Cluster*: A new configuration parameter `ODirect' causes
     `NDB' to attempt using `O_DIRECT' writes for LCP, backups, and redo
     logs, often lowering CPU usage.

   * It is now possible to set the size of redo log files (fragment log
     files) using the `FragmentLogFileSize' configuration parameter.

Bugs fixed:

   * *MySQL Cluster*: Having large amounts of memory locked caused
     swapping to disk.  (Bug#28751 (http://bugs.mysql.com/28751))

   * *MySQL Cluster*: LCP files were not removed following an initial
     system restart.  (Bug#28726 (http://bugs.mysql.com/28726))

   * *Disk Data*: Repeated `INSERT' and `DELETE' operations on a Disk
     Data table having one or more large `VARCHAR' columns could cause
     data nodes to fail.  (Bug#20612 (http://bugs.mysql.com/20612))


File: manual.info,  Node: mysql-cluster-news-5-1-15-ndb-6-1-10,  Next: mysql-cluster-news-5-1-15-ndb-6-1-9,  Prev: mysql-cluster-news-5-1-15-ndb-6-1-11,  Up: mysql-cluster-news-6-1

20.17.3.14 Changes in MySQL Cluster NDB 6.1.10 (5.1.15-ndb-6.1.10) (30 May 2007)
................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.1 release.

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.1 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.15 (see *Note news-5-1-15::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *MySQL Cluster*: A new `times' printout was added in the `ndbd'
     watchdog thread.

   * *MySQL Cluster*: Some unneeded printouts in the `ndbd' out file
     were removed.

   * The names of some log and other files were changed to avoid issues
     with the `tar' command's 99-character filename limit.

Bugs fixed:

   * *MySQL Cluster*: A regression in the heartbeat monitoring code
     could lead to node failure under high load. This issue affected
     MySQL 5.1.19 and MySQL Cluster NDB 6.1.10 only.  (Bug#28783
     (http://bugs.mysql.com/28783))

   * *MySQL Cluster*: A corrupt schema file could cause a `File already
     open' error.  (Bug#28770 (http://bugs.mysql.com/28770))

   * *MySQL Cluster*: Setting `InitialNoOpenFiles' equal to
     `MaxNoOfOpenFiles' caused an error. This was due to the fact that
     the actual value of `MaxNoOfOpenFiles' as used by the cluster was
     offset by 1 from the value set in `config.ini'.  (Bug#28749
     (http://bugs.mysql.com/28749))

   * *MySQL Cluster*: A race condition could result when non-master
     nodes (in addition to the master node) tried to update active
     status due to a local checkpoint (that is, between `NODE_FAILREP'
     and `COPY_GCIREQ' events). Now only the master updates the active
     status.  (Bug#28717 (http://bugs.mysql.com/28717))

   * *MySQL Cluster*: A fast global checkpoint under high load with
     high usage of the redo buffer caused data nodes to fail.
     (Bug#28653 (http://bugs.mysql.com/28653))

   * *Disk Data*: When loading data into a cluster following a version
     upgrade, the data nodes could forcibly shut down due to page and
     buffer management failures (that is, `ndbrequire' failures in
     `PGMAN').  (Bug#28525 (http://bugs.mysql.com/28525))


File: manual.info,  Node: mysql-cluster-news-5-1-15-ndb-6-1-9,  Next: mysql-cluster-news-5-1-15-ndb-6-1-8,  Prev: mysql-cluster-news-5-1-15-ndb-6-1-10,  Up: mysql-cluster-news-6-1

20.17.3.15 Changes in MySQL Cluster NDB 6.1.9 (5.1.15-ndb-6.1.9) (24 May 2007)
..............................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.1 release.

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.1 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.15 (see *Note news-5-1-15::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Bugs fixed:

   * *MySQL Cluster*: When an API node sent more than 1024 signals in a
     single batch, `NDB' would process only the first 1024 of these,
     and then hang.  (Bug#28443 (http://bugs.mysql.com/28443))

   * *Disk Data*: The cluster backup process scanned in `ACC' index
     order, which had bad effects for disk data.  (Bug#28593
     (http://bugs.mysql.com/28593))


File: manual.info,  Node: mysql-cluster-news-5-1-15-ndb-6-1-8,  Next: mysql-cluster-news-5-1-15-ndb-6-1-7,  Prev: mysql-cluster-news-5-1-15-ndb-6-1-9,  Up: mysql-cluster-news-6-1

20.17.3.16 Changes in MySQL Cluster NDB 6.1.8 (5.1.15-ndb-6.1.8) (05 May 2007)
..............................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.1 release.

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.1 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.15 (see *Note news-5-1-15::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Bugs fixed:

   * *MySQL Cluster*: Local checkpoint files relating to dropped `NDB'
     tables were not removed.  (Bug#28348 (http://bugs.mysql.com/28348))

   * *MySQL Cluster*: Repeated insertion of data generated by
     `mysqldump' into `NDB' tables could eventually lead to failure of
     the cluster.  (Bug#27437 (http://bugs.mysql.com/27437))

   * *Disk Data*: Extremely large inserts into Disk Data tables could
     lead to data node failure in some circumstances.  (Bug#27942
     (http://bugs.mysql.com/27942))

   * *Cluster API*: In a multi-operation transaction, a delete
     operation followed by the insertion of an implicit `NULL' failed to
     overwrite an existing value.  (Bug#20535
     (http://bugs.mysql.com/20535))

   * Setting `MaxNoOfTables' very low and relative to `DataMemory'
     caused `Out of memory in Ndb Kernel' errors when inserting
     relatively small amounts of data into NDB tables.  (Bug#24173
     (http://bugs.mysql.com/24173))


File: manual.info,  Node: mysql-cluster-news-5-1-15-ndb-6-1-7,  Next: mysql-cluster-news-5-1-15-ndb-6-1-6,  Prev: mysql-cluster-news-5-1-15-ndb-6-1-8,  Up: mysql-cluster-news-6-1

20.17.3.17 Changes in MySQL Cluster NDB 6.1.7 (5.1.15-ndb-6.1.7) (05 May 2007)
..............................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.1 release.

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.1 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.15 (see *Note news-5-1-15::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *Cluster Replication*: *Incompatible Change*: The schema for the
     `ndb_apply_status' table in the `mysql' system database has
     changed. When upgrading to this release from a previous MySQL
     Cluster NDB 6.x or mainline MySQL 5.1 release, you must drop the
     `mysql.ndb_apply_status' table, then restart the server in order
     for the table to be re-created with the new schema.

     See *Note mysql-cluster-replication-schema::, for additional
     information.

Bugs fixed:

   * *MySQL Cluster*: The cluster waited 30 seconds instead of 30
     milliseconds before reading table statistics.  (Bug#28093
     (http://bugs.mysql.com/28093))

   * *MySQL Cluster*: Under certain rare circumstances, `ndbd' could
     get caught in an infinite loop when one transaction took a read
     lock and then a second transaction attempted to obtain a write
     lock on the same tuple in the lock queue.  (Bug#28073
     (http://bugs.mysql.com/28073))

   * *MySQL Cluster*: Under some circumstances, a node restart could
     fail to update the Global Checkpoint Index (GCI).  (Bug#28023
     (http://bugs.mysql.com/28023))

   * *MySQL Cluster*: An `INSERT' followed by a delete `DELETE' on the
     same `NDB' table caused a memory leak.  (Bug#27756
     (http://bugs.mysql.com/27756)) This regression was introduced by
     Bug#20612 (http://bugs.mysql.com/20612)

   * *MySQL Cluster*: Under certain rare circumstances performing a
     `DROP TABLE' or `TRUNCATE' on an `NDB' table could cause a node
     failure or forced cluster shutdown.  (Bug#27581
     (http://bugs.mysql.com/27581))

   * *MySQL Cluster*: Memory usage of a `mysqld' process grew even
     while idle.  (Bug#27560 (http://bugs.mysql.com/27560))

   * *MySQL Cluster*: Performing a delete followed by an insert during
     a local checkpoint could cause a `Rowid already allocated' error.
     (Bug#27205 (http://bugs.mysql.com/27205))

   * *Cluster Replication*: *Disk Data*: An issue with replication of
     Disk Data tables could in some cases lead to node failure.
     (Bug#28161 (http://bugs.mysql.com/28161))

   * *Disk Data*: Changes to a Disk Data table made as part of a
     transaction could not be seen by the client performing the changes
     until the transaction had been committed.  (Bug#27757
     (http://bugs.mysql.com/27757))

   * *Disk Data*: When restarting a data node following the creation of
     a large number of Disk Data objects (approximately 200 such
     objects), the cluster could not assign a node ID to the restarting
     node.  (Bug#25741 (http://bugs.mysql.com/25741))

   * *Disk Data*: Changing a column specification or issuing a
     `TRUNCATE' statement on a Disk Data table caused the table to
     become an in-memory table.

     This fix supersedes an incomplete fix that was made for this issue
     in MySQL 5.1.15.  (Bug#24667 (http://bugs.mysql.com/24667),
     Bug#25296 (http://bugs.mysql.com/25296))

   * *Cluster Replication*: Some queries that updated multiple tables
     were not backed up correctly.  (Bug#27748
     (http://bugs.mysql.com/27748))

   * *Cluster Replication*: It was possible for API nodes to begin
     interacting with the cluster subscription manager before they were
     fully connected to the cluster.  (Bug#27728
     (http://bugs.mysql.com/27728))

   * *Cluster Replication*: Under very high loads, checkpoints could be
     read or written with checkpoint indexes out of order.  (Bug#27651
     (http://bugs.mysql.com/27651))

   * *Cluster API*: An issue with the way in which the
     `NdbDictionary::Dictionary::listEvents()' method freed resources
     could sometimes lead to memory corruption.  (Bug#27663
     (http://bugs.mysql.com/27663))

   * `mysqldump' could not dump log tables.  (Bug#26121
     (http://bugs.mysql.com/26121))

   * The `--with-readline' option for `configure' did not work for
     commercial source packages, but no error message was printed to
     that effect. Now a message is printed.  (Bug#25530
     (http://bugs.mysql.com/25530))


File: manual.info,  Node: mysql-cluster-news-5-1-15-ndb-6-1-6,  Next: mysql-cluster-news-5-1-15-ndb-6-1-5,  Prev: mysql-cluster-news-5-1-15-ndb-6-1-7,  Up: mysql-cluster-news-6-1

20.17.3.18 Changes in MySQL Cluster NDB 6.1.6 (5.1.15-ndb-6.1.6) (Not released)
...............................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.1 release.

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.1 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.15 (see *Note news-5-1-15::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *Cluster Replication*: *Incompatible Change*: The schema for the
     `ndb_apply_status' table in the `mysql' system database has
     changed. When upgrading to this release from a previous MySQL
     Cluster NDB 6.x or mainline MySQL 5.1 release, you must drop the
     `mysql.ndb_apply_status' table, then restart the server in order
     for the table to be re-created with the new schema.

     See *Note mysql-cluster-replication-schema::, for additional
     information.

Bugs fixed:

   * *MySQL Cluster*: A data node failing while another data node was
     restarting could leave the cluster in an inconsistent state. In
     certain rare cases, this could lead to a race condition and the
     eventual forced shutdown of the cluster.  (Bug#27466
     (http://bugs.mysql.com/27466))

   * *MySQL Cluster*: It was not possible to set
     `LockPagesInMainMemory' equal to `0'.  (Bug#27291
     (http://bugs.mysql.com/27291))

   * *MySQL Cluster*: A race condition could sometimes occur if the
     node acting as master failed while node IDs were still being
     allocated during startup.  (Bug#27286
     (http://bugs.mysql.com/27286))

   * *MySQL Cluster*: When a data node was taking over as the master
     node, a race condition could sometimes occur as the node was
     assuming responsibility for handling of global checkpoints.
     (Bug#27283 (http://bugs.mysql.com/27283))

   * *MySQL Cluster*: `mysqld' could crash shortly after a data node
     failure following certain DML operations.  (Bug#27169
     (http://bugs.mysql.com/27169))

   * *MySQL Cluster*: The same failed request from an API node could be
     handled by the cluster multiple times, resulting in reduced
     performance.  (Bug#27087 (http://bugs.mysql.com/27087))

   * *MySQL Cluster*: The failure of a data node while restarting could
     cause other data nodes to hang or crash.  (Bug#27003
     (http://bugs.mysql.com/27003))

   * *MySQL Cluster*: `mysqld' processes would sometimes crash under
     high load.

     *Note*:

     This fix improves on and replaces a fix for this bug that was made
     in MySQL Cluster NDB 6.1.5.

     (Bug#26825 (http://bugs.mysql.com/26825))

   * *Disk Data*: `DROP INDEX' on a Disk Data table did not always move
     data from memory into the tablespace.  (Bug#25877
     (http://bugs.mysql.com/25877))

   * *Cluster Replication*: Trying to replicate a large number of
     frequent updates with a relatively small relay log
     (`max-relay-log-size' set to 1M or less) could cause the slave to
     crash.  (Bug#27529 (http://bugs.mysql.com/27529))

   * *Cluster API*: An issue with the way in which the
     `NdbDictionary::Dictionary::listEvents()' method freed resources
     could sometimes lead to memory corruption.  (Bug#27663
     (http://bugs.mysql.com/27663))

   * *Cluster API*: A delete operation using a scan followed by an
     insert using a scan could cause a data node to fail.  (Bug#27203
     (http://bugs.mysql.com/27203))


File: manual.info,  Node: mysql-cluster-news-5-1-15-ndb-6-1-5,  Next: mysql-cluster-news-5-1-15-ndb-6-1-4,  Prev: mysql-cluster-news-5-1-15-ndb-6-1-6,  Up: mysql-cluster-news-6-1

20.17.3.19 Changes in MySQL Cluster NDB 6.1.5 (5.1.15-ndb-6.1.5) (15 March 2007)
................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.1 release.

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.1 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.15 (see *Note news-5-1-15::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *Cluster Replication*: *Incompatible Change*: The schema for the
     `ndb_apply_status' table in the `mysql' system database has
     changed. When upgrading to this release from a previous MySQL
     Cluster NDB 6.x or mainline MySQL 5.1 release, you must drop the
     `mysql.ndb_apply_status' table, then restart the server in order
     for the table to be re-created with the new schema.

     See *Note mysql-cluster-replication-schema::, for additional
     information.

Bugs fixed:

   * *MySQL Cluster*: Creating a table on one SQL node while in single
     user mode caused other SQL nodes to crash.  (Bug#26997
     (http://bugs.mysql.com/26997))

   * *MySQL Cluster*: `mysqld' processes would sometimes crash under
     high load.

     *Note*:

     This fix was reverted in MySQL Cluster NDB 6.1.6.

     (Bug#26825 (http://bugs.mysql.com/26825))

   * *MySQL Cluster*: An infinite loop in an internal logging function
     could cause trace logs to fill up with `Unknown Signal type' error
     messages and thus grow to unreasonable sizes.  (Bug#26720
     (http://bugs.mysql.com/26720))

   * *Disk Data*: When creating a log file group, setting
     `INITIAL_SIZE' to less than `UNDO_BUFFER_SIZE' caused data nodes
     to crash.  (Bug#25743 (http://bugs.mysql.com/25743))


File: manual.info,  Node: mysql-cluster-news-5-1-15-ndb-6-1-4,  Next: mysql-cluster-news-5-1-15-ndb-6-1-3,  Prev: mysql-cluster-news-5-1-15-ndb-6-1-5,  Up: mysql-cluster-news-6-1

20.17.3.20 Changes in MySQL Cluster NDB 6.1.4 (5.1.15-ndb-6.1.4) (09 March 2007))
.................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.1 release.

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.1 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.15 (see *Note news-5-1-15::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *MySQL Cluster*: An `--ndb-wait-connected' option has been added
     for `mysqld'. It causes `mysqld' wait a specified amount of time
     to be connected to the cluster before accepting client connections.
     See here, for more information.

   * *Cluster API*: It is now possible to specify the transaction
     coordinator when starting a transaction. See
     `Ndb::startTransaction()'
     (http://dev.mysql.com/doc/ndbapi/en/class-ndb-starttransaction.html),
     for more information.

   * *Cluster API*: It is now possible to iterate over all existing
     `Ndb' objects using three new methods of the
     `Ndb_cluster_connection' class:

        * `lock_ndb_objects()'

        * `get_next_ndb_object()'

        * `unlock_ndb_objects()'

     For more information about these methods and their use, see
     `ndb_cluster_connection::get_next_ndb_object()'
     (http://dev.mysql.com/doc/ndbapi/en/class-ndb-cluster-connection-get-next-ndb-object.html),
     in the MySQL Cluster API Guide.

   * Data node memory allocation has been improved. On 32-bit
     platforms, it should now be possible to use close to 3GB RAM for
     `IndexMemory' and `DataMemory' combined.

Bugs fixed:

   * *MySQL Cluster*: Using only the `--print_data' option (and no
     other options) with `ndb_restore' caused `ndb_restore' to fail.
     (Bug#26741 (http://bugs.mysql.com/26741)) This regression was
     introduced by Bug#14612 (http://bugs.mysql.com/14612)

   * *MySQL Cluster*: An inadvertent use of unaligned data caused
     `ndb_restore' to fail on some 64-bit platforms, including Sparc
     and Itanium-2.  (Bug#26739 (http://bugs.mysql.com/26739))

   * Assigning a node ID greater than 63 to an SQL node caused an out
     of bounds error in `mysqld'. It should now be possible to assign
     to SQL nodes node IDs up to 255.  (Bug#26663
     (http://bugs.mysql.com/26663))


File: manual.info,  Node: mysql-cluster-news-5-1-15-ndb-6-1-3,  Next: mysql-cluster-news-5-1-15-ndb-6-1-2,  Prev: mysql-cluster-news-5-1-15-ndb-6-1-4,  Up: mysql-cluster-news-6-1

20.17.3.21 Changes in MySQL Cluster NDB 6.1.3 (5.1.15-ndb-6.1.3) (25 February 2007)
...................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.1 release.

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.1 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.15 (see *Note news-5-1-15::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *MySQL Cluster*: The `ndbd_redo_log_reader' utility is now part of
     the default build. For more information, see *Note
     mysql-cluster-utilities-ndbd-redo-log-reader::.

   * *MySQL Cluster*: The `ndb_show_tables' utility now displays
     information about table events. See *Note
     mysql-cluster-utilities-ndb-show-tables::, for more information.

   * *Cluster API*: A new `listEvents()' method has been added to the
     `Dictionary' class. See `Dictionary::listEvents()'
     (http://dev.mysql.com/doc/ndbapi/en/class-dictionary-listevents.html),
     for more information.

   * It is now possible to disable arbitration by setting
     `ArbitrationRank=0' on all management and SQL nodes.

Bugs fixed:

   * *MySQL Cluster*: An invalid pointer was returned following a
     `FSCLOSECONF' signal when accessing the REDO logs during a node
     restart or system restart.  (Bug#26515
     (http://bugs.mysql.com/26515))

   * *MySQL Cluster*: The InvalidUndoBufferSize error used the same
     error code (763) as the IncompatibleVersions error.
     InvalidUndoBufferSize now uses its own error code (779).
     (Bug#26490 (http://bugs.mysql.com/26490))

   * *MySQL Cluster*: The failure of a data node when restarting it with
     `--initial' could lead to failures of subsequent data node
     restarts.  (Bug#26481 (http://bugs.mysql.com/26481))

   * *MySQL Cluster*: Takeover for local checkpointing due to multiple
     failures of master nodes was sometimes incorrectly handled.
     (Bug#26457 (http://bugs.mysql.com/26457))

   * *MySQL Cluster*: The `LockPagesInMainMemory' parameter was not
     read until after distributed communication had already started
     between cluster nodes. When the value of this parameter was `1',
     this could sometimes result in data node failure due to missed
     heartbeats.  (Bug#26454 (http://bugs.mysql.com/26454))

   * *MySQL Cluster*: Under some circumstances, following the restart
     of a management node, all data nodes would connect to it normally,
     but some of them subsequently failed to log any events to the
     management node.  (Bug#26293 (http://bugs.mysql.com/26293))

   * *MySQL Cluster*: No appropriate error message was provided when
     there was insufficient REDO log file space for the cluster to
     start.  (Bug#25801 (http://bugs.mysql.com/25801))

   * *MySQL Cluster*: A memory allocation failure in `SUMA' (the
     cluster Subscription Manager) could cause the cluster to crash.
     (Bug#25239 (http://bugs.mysql.com/25239))

   * *MySQL Cluster*: The message `Error 0 in readAutoIncrementValue():
     no Error' was written to the error log whenever `SHOW TABLE
     STATUS' was performed on a Cluster table that did not have an
     `AUTO_INCREMENT' column.

     *Note*:

     This improves on and supersedes an earlier fix that was made for
     this issue in MySQL 5.1.12.

     (Bug#21033 (http://bugs.mysql.com/21033))

   * *Disk Data*: A memory overflow could occur with tables having a
     large amount of data stored on disk, or with queries using a very
     high degree of parallelism on Disk Data tables.  (Bug#26514
     (http://bugs.mysql.com/26514))

   * *Disk Data*: Use of a tablespace whose `INITIAL_SIZE' was greater
     than 1 GB could cause the cluster to crash.  (Bug#26487
     (http://bugs.mysql.com/26487))


File: manual.info,  Node: mysql-cluster-news-5-1-15-ndb-6-1-2,  Next: mysql-cluster-news-5-1-15-ndb-6-1-1,  Prev: mysql-cluster-news-5-1-15-ndb-6-1-3,  Up: mysql-cluster-news-6-1

20.17.3.22 Changes in MySQL Cluster NDB 6.1.2 (5.1.15-ndb-6.1.2) (07 February 2007)
...................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.1 release.

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

This Beta release incorporates all bugfixes and changes made in
previous MySQL Cluster NDB 6.1 releases, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.15 (see *Note news-5-1-15::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Bugs fixed:

   * *MySQL Cluster*: Using node IDs greater than 48 could sometimes
     lead to incorrect memory access and a subsequent forced shutdown
     of the cluster.  (Bug#26267 (http://bugs.mysql.com/26267))


File: manual.info,  Node: mysql-cluster-news-5-1-15-ndb-6-1-1,  Next: mysql-cluster-news-5-1-14-ndb-6-1-0,  Prev: mysql-cluster-news-5-1-15-ndb-6-1-2,  Up: mysql-cluster-news-6-1

20.17.3.23 Changes in MySQL Cluster NDB 6.1.1 (5.1.15-ndb-6.1.1) (01 February 2007)
...................................................................................

This is a bugfix release, fixing recently discovered bugs in the
previous MySQL Cluster NDB 6.1 release.

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

This Beta release incorporates all bugfixes and changes made in the
previous MySQL Cluster NDB 6.1 release, as well as all bugfixes and
feature changes which were added in mainline MySQL 5.1 through MySQL
5.1.15 (see *Note news-5-1-15::).

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *MySQL Cluster*: A single cluster can now support up to 255 API
     nodes, including MySQL servers acting as SQL nodes. See *Note
     mysql-cluster-limitations-exclusive-to-cluster::, for more
     information.

Bugs fixed:

   * *MySQL Cluster*: A memory leak could cause problems during a node
     or cluster shutdown or failure.  (Bug#25997
     (http://bugs.mysql.com/25997))

   * *Cluster API*: *Disk Data*: A delete and a read performed in the
     same operation could cause one or more data nodes to crash. This
     could occur when the operation affected more than 5 columns
     concurrently, or when one or more of the columns was of the
     `VARCHAR' type and was stored on disk.  (Bug#25794
     (http://bugs.mysql.com/25794))

   * An element could sometimes be inserted twice into the hash table,
     causing a data node to crash.  (Bug#25286
     (http://bugs.mysql.com/25286))


File: manual.info,  Node: mysql-cluster-news-5-1-14-ndb-6-1-0,  Prev: mysql-cluster-news-5-1-15-ndb-6-1-1,  Up: mysql-cluster-news-6-1

20.17.3.24 Changes in MySQL Cluster NDB 6.1.0 (5.1.14-ndb-6.1.0) (20 December 2006)
...................................................................................

This is the first MySQL Cluster NDB 6.1 release, incorporating new
features and bugfixes made for the `NDBCLUSTER' storage engine made
since branching from MySQL 5.1.14 standard (see *Note news-5-1-14::).

MySQL Cluster NDB 6.1 no longer in development

MySQL Cluster NDB 6.1 (formerly known as `MySQL Cluster Carrier Grade
Edition 6.1.x') is no longer being developed or maintained; if you are
using a MySQL Cluster NDB 6.1 release, you should consider upgrading to
MySQL Cluster NDB 6.2 or 6.3.

*Note*:

Please refer to our bug database at `http://bugs.mysql.com/' for more
details about the individual bugs fixed in this version.

Functionality added or changed:

   * *MySQL Cluster*: A new configuration parameter
     `MemReportFrequency' allows for additional control of data node
     memory usage. Previously, only warnings at predetermined
     percentages of memory allocation were given; setting this
     parameter allows for that behavior to be overridden. For more
     information, see *Note mysql-cluster-ndbd-definition::.

Bugs fixed:

   * *MySQL Cluster*: When a data node was shut down using the
     management client `STOP' command, a connection event
     (`NDB_LE_Connected') was logged instead of a disconnection event
     (`NDB_LE_Disconnected').  (Bug#22773 (http://bugs.mysql.com/22773))

   * *MySQL Cluster*: `SELECT' statements with a `BLOB' or `TEXT'
     column in the selected column list and a `WHERE' condition
     including a primary key lookup on a `VARCHAR' primary key produced
     empty result sets.  (Bug#19956 (http://bugs.mysql.com/19956))

   * *Disk Data*: `MEDIUMTEXT' columns of Disk Data tables were stored
     in memory rather than on disk, even if the columns were not
     indexed.  (Bug#25001 (http://bugs.mysql.com/25001))

   * *Disk Data*: Performing a node restart with a newly dropped Disk
     Data table could lead to failure of the node during the restart.
     (Bug#24917 (http://bugs.mysql.com/24917))

   * *Disk Data*: When restoring from backup a cluster containing any
     Disk Data tables with hidden primary keys, a node failure resulted
     which could lead to a crash of the cluster.  (Bug#24166
     (http://bugs.mysql.com/24166))

   * *Disk Data*: Repeated `CREATE', `DROP', or `TRUNCATE' in various
     combinations with system restarts between these operations could
     lead to the eventual failure of a system restart.  (Bug#21948
     (http://bugs.mysql.com/21948))

   * *Disk Data*: Extents that should have been available for re-use
     following a `DROP TABLE' operation were not actually made
     available again until after the cluster had performed a local
     checkpoint.  (Bug#17605 (http://bugs.mysql.com/17605))

   * *Cluster API*: Invoking the `NdbTransaction::execute()' method
     using execution type `Commit' and abort option `AO_IgnoreError'
     could lead to a crash of the transaction coordinator (`DBTC').
     (Bug#25090 (http://bugs.mysql.com/25090))

   * *Cluster API*: A unique index lookup on a non-existent tuple could
     lead to a data node timeout (error 4012).  (Bug#25059
     (http://bugs.mysql.com/25059))

   * *Cluster API*: When using the `NdbTransaction::execute()' method,
     a very long timeout (greater than 5 minutes) could result if the
     last data node being polled was disconnected from the cluster.
     (Bug#24949 (http://bugs.mysql.com/24949))

   * *Cluster API*: Due to an error in the computation of table
     fragment arrays, some transactions were not executed from the
     correct starting point.  (Bug#24914 (http://bugs.mysql.com/24914))

   * Under certain rare circumstances, local checkpoints were not
     performed properly, leading to an inability to restart one or more
     data nodes.  (Bug#24664 (http://bugs.mysql.com/24664))


File: manual.info,  Node: partitioning,  Next: spatial-extensions,  Prev: mysql-cluster,  Up: Top

21 Partitioning
***************

* Menu:

* partitioning-overview::        Overview of Partitioning in MySQL
* partitioning-types::           Partition Types
* partitioning-management::      Partition Management
* partitioning-pruning::         Partition Pruning
* partitioning-limitations::     Restrictions and Limitations on Partitioning

This chapter discusses _user-defined partitioning_, as implemented in
MySQL 5.1.

An introduction to partitioning and partitioning concepts may be found
in *Note partitioning-overview::.

MySQL supports several types of partitioning, which are discussed in
*Note partitioning-types::, as well as subpartitioning, which is
described in *Note partitioning-subpartitions::.

Methods of adding, removing, and altering partitions in existing
partitioned tables are covered in *Note partitioning-management::.

Table maintenance commands for use with partitioned tables are
discussed in *Note partitioning-maintenance::.

Beginning with MySQL 5.1.6, the `PARTITIONS' table in the
`INFORMATION_SCHEMA' database provides information about partitions and
partitioned tables. See *Note partitions-table::, for more information;
for some examples of queries against this table, see *Note
partitioning-handling-nulls::.

*Important*:

Partitioned tables created with MySQL versions prior to 5.1.6 cannot be
read by a 5.1.6 or later MySQL Server. In addition, the
`INFORMATION_SCHEMA.TABLES' table cannot be used if such tables are
present on a 5.1.6 server. Beginning with MySQL 5.1.7, a suitable
warning message is generated instead, to alert the user that
incompatible partitioned tables have been found by the server.

If you are using partitioned tables which were created in MySQL 5.1.5
or earlier, be sure to see *Note news-5-1-6:: for more information and
suggested workarounds _before_ upgrading to MySQL 5.1.6 or later.

The partitioning implementation in MySQL 5.1 is still undergoing
development. For known issues with MySQL partitioning, see *Note
partitioning-limitations::, where we have noted these.

You may also find the following resources to be useful when working
with partitioned tables.

Additional Resources

Other sources of information about user-defined partitioning in MySQL
include the following:

   * MySQL Partitioning Forum (http://forums.mysql.com/list.php?106)

     This is the official discussion forum for those interested in or
     experimenting with MySQL Partitioning technology. It features
     announcements and updates from MySQL developers and others. It is
     monitored by members of the Partitioning Development and
     Documentation Teams.

   * Mikael Ronstro"m's Blog (http://mikaelronstrom.blogspot.com/)

     MySQL Partitioning Architect and Lead Developer Mikael Ronstro"m
     frequently posts articles here concerning his work with MySQL
     Partitioning and MySQL Cluster.

   * PlanetMySQL (http://www.planetmysql.org/)

     A MySQL news site featuring MySQL-related blogs, which should be
     of interest to anyone using my MySQL. We encourage you to check
     here for links to blogs kept by those working with MySQL
     Partitioning, or to have your own blog added to those covered.

MySQL 5.1 binaries are available from
`http://dev.mysql.com/downloads/mysql/5.1.html'.  However, for the
latest partitioning bugfixes and feature additions, you can obtain the
source from our Bazaar repository. To enable partitioning, you need to
compile the server using the `--with-partition' option. For more
information about building MySQL, see *Note installing-source::. If you
have problems compiling a partitioning-enabled MySQL 5.1 build, check
the MySQL Partitioning Forum (http://forums.mysql.com/list.php?106) and
ask for assistance there if you do not find a solution to your problem
already posted.


File: manual.info,  Node: partitioning-overview,  Next: partitioning-types,  Prev: partitioning,  Up: partitioning

21.1 Overview of Partitioning in MySQL
======================================

This section provides a conceptual overview of partitioning in MySQL
5.1.

For information on partitioning restrictions and feature limitations,
see *Note partitioning-limitations::.

The SQL standard does not provide much in the way of guidance regarding
the physical aspects of data storage. The SQL language itself is
intended to work independently of any data structures or media
underlying the schemas, tables, rows, or columns with which it works.
Nonetheless, most advanced database management systems have evolved
some means of determining the physical location to be used for storing
specific pieces of data in terms of the filesystem, hardware or even
both. In MySQL, the `InnoDB' storage engine has long supported the
notion of a tablespace, and the MySQL Server, even prior to the
introduction of partitioning, could be configured to employ different
physical directories for storing different databases (see *Note
symbolic-links::, for an explanation of how this is done).

_Partitioning_ takes this notion a step further, by allowing you to
distribute portions of individual tables across a filesystem according
to rules which you can set largely as needed. In effect, different
portions of a table are stored as separate tables in different
locations. The user-selected rule by which the division of data is
accomplished is known as a _partitioning function_, which in MySQL can
be the modulus, simple matching against a set of ranges or value lists,
an internal hashing function, or a linear hashing function. The
function is selected according to the partitioning type specified by
the user, and takes as its parameter the value of a user-supplied
expression. This expression can be either an integer column value, or a
function acting on one or more column values and returning an integer.
The value of this expression is passed to the partitioning function,
which returns an integer value representing the number of the partition
in which that particular record should be stored. This function must be
non-constant and non-random. It may not contain any queries, but may
use an SQL expression that is valid in MySQL, as long as that
expression returns either `NULL' or an integer INTVAL such that

     -MAXVALUE <= INTVAL <= MAXVALUE

(`MAXVALUE' is used to represent the least upper bound for the type of
integer in question.  `-MAXVALUE' represents the greatest lower bound.)
There are some additional restrictions on partitioning functions; see
*Note partitioning-limitations::, for more information about these.

Examples of partitioning functions can be found in the discussions of
partitioning types later in this chapter (see *Note
partitioning-types::), as well as in the partitioning syntax
descriptions given in *Note create-table::.

This is known as _horizontal partitioning_ -- that is, different rows
of a table may be assigned to different physical partitions. MySQL 5.1
does not support _vertical partitioning_, in which different columns of
a table are assigned to different physical partitions. There are not at
this time any plans to introduce vertical partitioning into MySQL 5.1.

Partitioning support is included in all binary releases of MySQL 5.1.
If you are compiling MySQL 5.1 from source, the build must be
configured using `--with-partition' to enable partitioning.

If the MySQL binary is built with partitioning support, nothing further
needs to be done in order to enable it (for example, no special entries
are required in your `my.cnf' file). You can determine whether your
MySQL server supports partitioning by means of a `SHOW VARIABLES'
command such as this one:

     mysql> SHOW VARIABLES LIKE '%partition%';

     +-------------------+-------+
     | Variable_name     | Value |
     +-------------------+-------+
     | have_partitioning | YES   |
     +-------------------+-------+
     1 row in set (0.00 sec)

If you do not see the `have_partitioning' variable with the value `YES'
listed as shown above in the output of an appropriate `SHOW VARIABLES',
then your version of MySQL does not support partitioning.

*Note*:

Prior to MySQL 5.1.6, this variable was named `have_partition_engine'.
(Bug#16718 (http://bugs.mysql.com/16718))

For creating partitioned tables, you can use most storage engines that
are supported by your MySQL server; the MySQL partitioning engine runs
in a separate layer and can interact with any of these. In MySQL 5.1,
all partitions of the same partitioned table must use the same storage
engine; for example, you cannot use `MyISAM' for one partition and
`InnoDB' for another. However, there is nothing preventing you from
using different storage engines for different partitioned tables on the
same MySQL server or even in the same database.

*Note*:

MySQL partitioning cannot be used with the `MERGE' or `CSV' storage
engines. Beginning with MySQL 5.1.15, `FEDERATED' tables also cannot be
partitioned (Bug#22451 (http://bugs.mysql.com/22451)). Prior to MySQL
5.1.6, it was also not feasible to create a partitioned table using the
`BLACKHOLE' storage engine (Bug#14524 (http://bugs.mysql.com/14524)).
Partitioning by `KEY' is possible with `NDBCLUSTER', but other types of
user-defined partitioning are not supported for tables using this
storage engine.

To employ a particular storage engine for a partitioned table, it is
necessary only to use the `[STORAGE] ENGINE' option just as you would
for a non-partitioned table. However, you should keep in mind that
`[STORAGE] ENGINE' (and other table options) need to be listed _before_
any partitioning options are used in a `CREATE TABLE' statement. This
example shows how to create a table that is partitioned by hash into 6
partitions and which uses the `InnoDB' storage engine:

     CREATE TABLE ti (id INT, amount DECIMAL(7,2), tr_date DATE)
         ENGINE=INNODB
         PARTITION BY HASH( MONTH(tr_date) )
         PARTITIONS 6;

*Note*:

Each `PARTITION' clause can include a `[STORAGE] ENGINE' option, but in
MySQL 5.1 this has no effect.

*Important*:

Partitioning applies to all data and indexes of a table; you cannot
partition only the data and not the indexes, or _vice versa_, nor can
you partition only a portion of the table.

Data and indexes for each partition can be assigned to a specific
directory using the `DATA DIRECTORY' and `INDEX DIRECTORY' options for
the `PARTITION' clause of the `CREATE TABLE' statement used to create
the partitioned table.

*Note*:

Prior to MySQL 5.1.18, these options were permitted even when the
`NO_DIR_IN_CREATE' server SQL mode was in effect. (Bug#24633
(http://bugs.mysql.com/24633))

The `DATA DIRECTORY' and `INDEX DIRECTORY' options have no effect when
defining partitions for tables using the `InnoDB' storage engine.

`DATA DIRECTORY' and `INDEX DIRECTORY' are not supported for individual
partitions or subpartitions on Windows. Beginning with MySQL 5.1.24,
these options are ignored on Windows, except that a warning is
generated. (Bug#30459 (http://bugs.mysql.com/30459))

In addition, `MAX_ROWS' and `MIN_ROWS' can be used to determine the
maximum and minimum numbers of rows, respectively, that can be stored in
each partition. See *Note partitioning-management::, for more
information on these options.

Some of the advantages of partitioning include:

   * Being able to store more data in one table than can be held on a
     single disk or filesystem partition.

   * Data that loses its usefulness can often be easily be removed from
     the table by dropping the partition containing only that data.
     Conversely, the process of adding new data can in some cases be
     greatly facilitated by adding a new partition specifically for
     that data.

   * Some queries can be greatly optimized in virtue of the fact that
     data satisfying a given `WHERE' clause can be stored only on one
     or more partitions, thereby excluding any remaining partitions
     from the search. Because partitions can be altered after a
     partitioned table has been created, you can reorganize your data
     to enhance frequent queries that may not have been so when the
     partitioning scheme was first set up. This capability, sometimes
     referred to as _partition pruning_, was implemented in MySQL
     5.1.6. For more information, see *Note partitioning-pruning::.

Other benefits usually associated with partitioning include those in
the following list. These features are not currently implemented in
MySQL Partitioning, but are high on our list of priorities.

   * Queries involving aggregate functions such as `SUM()' and
     `COUNT()' can easily be parallelized. A simple example of such a
     query might be `SELECT salesperson_id, COUNT(orders) as order_total
     FROM sales GROUP BY salesperson_id;'. By `parallelized,' we mean
     that the query can be run simultaneously on each partition, and
     the final result obtained merely by summing the results obtained
     for all partitions.

   * Achieving greater query throughput in virtue of spreading data
     seeks over multiple disks.

Be sure to check this section and chapter frequently for updates as
Partitioning development continues.


File: manual.info,  Node: partitioning-types,  Next: partitioning-management,  Prev: partitioning-overview,  Up: partitioning

21.2 Partition Types
====================

* Menu:

* partitioning-range::           `RANGE' Partitioning
* partitioning-list::            `LIST' Partitioning
* partitioning-hash::            `HASH' Partitioning
* partitioning-key::             `KEY' Partitioning
* partitioning-subpartitions::   Subpartitioning
* partitioning-handling-nulls::  How MySQL Partitioning Handles `NULL' Values

This section discusses the types of partitioning which are available in
MySQL 5.1. These include:

   * *`RANGE' partitioning*: Assigns rows to partitions based on column
     values falling within a given range. See *Note
     partitioning-range::.

   * *`LIST' partitioning*: Similar to partitioning by range, except
     that the partition is selected based on columns matching one of a
     set of discrete values. See *Note partitioning-list::.

   * *`HASH' partitioning*: A partition is selected based on the value
     returned by a user-defined expression that operates on column
     values in rows to be inserted into the table. The function may
     consist of any expression valid in MySQL that yields a
     non-negative integer value. See *Note partitioning-hash::.

   * *`KEY' partitioning*: Similar to partitioning by hash, except that
     only one or more columns to be evaluated are supplied, and the
     MySQL server provides its own hashing function. These columns can
     contain other than integer values, since the hashing function
     supplied by MySQL guarantees an integer result regardless of the
     column data type. See *Note partitioning-key::.

A very common use of database partitioning is to segregate data by
date. Some database systems support explicit date partitioning, which
MySQL does not implement in 5.1. However, it is not difficult in MySQL
to create partitioning schemes based on `DATE', `TIME', or `DATETIME'
columns, or based on expressions making use of such columns.

When partitioning by `KEY' or `LINEAR KEY', you can use a `DATE',
`TIME', or `DATETIME' column as the partitioning column without
performing any modification of the column value. For example, this
table creation statement is perfectly valid in MySQL:

     CREATE TABLE members (
         firstname VARCHAR(25) NOT NULL,
         lastname VARCHAR(25) NOT NULL,
         username VARCHAR(16) NOT NULL,
         email VARCHAR(35),
         joined DATE NOT NULL
     )
     PARTITION BY KEY(joined)
     PARTITIONS 6;

MySQL's other partitioning types, however, require a partitioning
expression that yields an integer value or `NULL'. If you wish to use
date-based partitioning by `RANGE', `LIST', `HASH', or `LINEAR HASH',
you can simply employ a function that operates on a `DATE', `TIME', or
`DATETIME' column and returns such a value, as shown here:

     CREATE TABLE members (
         firstname VARCHAR(25) NOT NULL,
         lastname VARCHAR(25) NOT NULL,
         username VARCHAR(16) NOT NULL,
         email VARCHAR(35),
         joined DATE NOT NULL
     )
     PARTITION BY RANGE( YEAR(joined) ) (
         PARTITION p0 VALUES LESS THAN (1960),
         PARTITION p1 VALUES LESS THAN (1970),
         PARTITION p2 VALUES LESS THAN (1980),
         PARTITION p3 VALUES LESS THAN (1990),
         PARTITION p4 VALUES LESS THAN MAXVALUE
     );

Additional examples of partitioning using dates may be found here:

   * *Note partitioning-range::

   * *Note partitioning-hash::

   * *Note partitioning-linear-hash::

For more complex examples of date-based partitioning, see:

   * *Note partitioning-pruning::

   * *Note partitioning-subpartitions::

MySQL partitioning is optimized for use with the `TO_DAYS()' and
`YEAR()' functions. However, you can use other date and time functions
that return an integer or `NULL', such as `WEEKDAY()', `DAYOFYEAR()', or
`MONTH()'. See *Note date-and-time-functions::, for more information
about such functions.

It is important to remember -- regardless of the type of partitioning
that you use -- that partitions are always numbered automatically and
in sequence when created, starting with `0'. When a new row is inserted
into a partitioned table, it is these partition numbers that are used in
identifying the correct partition. For example, if your table uses 4
partitions, these partitions are numbered `0', `1', `2', and `3'. For
the `RANGE' and `LIST' partitioning types, it is necessary to ensure
that there is a partition defined for each partition number. For `HASH'
partitioning, the user function employed must return an integer value
greater than `0'. For `KEY' partitioning, this issue is taken care of
automatically by the hashing function which the MySQL server employs
internally.

Names of partitions generally follow the rules governing other MySQL
identifiers, such as those for tables and databases.  However, you
should note that partition names are not case-sensitive. For example,
the following `CREATE TABLE' statement fails as shown:

     mysql> CREATE TABLE t2 (val INT)
         -> PARTITION BY LIST(val)(
         ->     PARTITION mypart VALUES IN (1,3,5),
         ->     PARTITION MyPart VALUES IN (2,4,6)
         -> );
     ERROR 1488 (HY000): Duplicate partition name mypart

Failure occurs because MySQL sees no difference between the partition
names `mypart' and `MyPart'.

When you specify the number of partitions for the table, this must be
expressed as a positive, non-zero integer literal with no leading
zeroes, and may not be an expression such as `0.8E+01' or `6-2', even
if it evaluates to an integer value. (Beginning with MySQL 5.1.12,
decimal fractions are no longer truncated, but instead are disallowed
entirely.)

In the sections that follow, we do not necessarily provide all possible
forms for the syntax that can be used for creating each partition type;
this information may be found in *Note create-table::.


File: manual.info,  Node: partitioning-range,  Next: partitioning-list,  Prev: partitioning-types,  Up: partitioning-types

21.2.1 `RANGE' Partitioning
---------------------------

A table that is partitioned by range is partitioned in such a way that
each partition contains rows for which the partitioning expression
value lies within a given range. Ranges should be contiguous but not
overlapping, and are defined using the `VALUES LESS THAN' operator. For
the next few examples, suppose that you are creating a table such as the
following to hold personnel records for a chain of 20 video stores,
numbered 1 through 20:

     CREATE TABLE employees (
         id INT NOT NULL,
         fname VARCHAR(30),
         lname VARCHAR(30),
         hired DATE NOT NULL DEFAULT '1970-01-01',
         separated DATE NOT NULL DEFAULT '9999-12-31',
         job_code INT NOT NULL,
         store_id INT NOT NULL
     );

This table can be partitioned by range in a number of ways, depending
on your needs. One way would be to use the `store_id' column. For
instance, you might decide to partition the table 4 ways by adding a
`PARTITION BY RANGE' clause as shown here:

     CREATE TABLE employees (
         id INT NOT NULL,
         fname VARCHAR(30),
         lname VARCHAR(30),
         hired DATE NOT NULL DEFAULT '1970-01-01',
         separated DATE NOT NULL DEFAULT '9999-12-31',
         job_code INT NOT NULL,
         store_id INT NOT NULL
     )
     PARTITION BY RANGE (store_id) (
         PARTITION p0 VALUES LESS THAN (6),
         PARTITION p1 VALUES LESS THAN (11),
         PARTITION p2 VALUES LESS THAN (16),
         PARTITION p3 VALUES LESS THAN (21)
     );

In this partitioning scheme, all rows corresponding to employees
working at stores 1 through 5 are stored in partition `p0', to those
employed at stores 6 through 10 are stored in partition `p1', and so
on. Note that each partition is defined in order, from lowest to
highest.  This is a requirement of the `PARTITION BY RANGE' syntax; you
can think of it as being analogous to a `switch ... case' in C or Java
in this regard.

It is easy to determine that a new row containing the data `(72,
'Michael', 'Widenius', '1998-06-25', NULL, 13)' is inserted into
partition `p2', but what happens when your chain adds a 21^st store?
Under this scheme, there is no rule that covers a row whose `store_id'
is greater than 20, so an error results because the server does not
know where to place it. You can keep this from occurring by using a
`catchall' `VALUES LESS THAN' clause in the `CREATE TABLE' statement
that provides for all values greater than highest value explicitly
named:

     CREATE TABLE employees (
         id INT NOT NULL,
         fname VARCHAR(30),
         lname VARCHAR(30),
         hired DATE NOT NULL DEFAULT '1970-01-01',
         separated DATE NOT NULL DEFAULT '9999-12-31',
         job_code INT NOT NULL,
         store_id INT NOT NULL
     )
     PARTITION BY RANGE (store_id) (
         PARTITION p0 VALUES LESS THAN (6),
         PARTITION p1 VALUES LESS THAN (11),
         PARTITION p2 VALUES LESS THAN (16),
         _PARTITION p3 VALUES LESS THAN MAXVALUE_
     );

*Note*:

Another way to avoid an error when no matching value is found is to use
the `IGNORE' keyword as part of the `INSERT' statement. For an example,
see *Note partitioning-list::. Also see *Note insert::, for general
information about `IGNORE'.

`MAXVALUE' represents an integer value that is always greater than the
largest possible integer value (in mathematical language, it serves as
a _least upper bound_). Now, any rows whose `store_id' column value is
greater than or equal to 16 (the highest value defined) are stored in
partition `p3'. At some point in the future -- when the number of
stores has increased to 25, 30, or more -- you can use an `ALTER TABLE'
statement to add new partitions for stores 21-25, 26-30, and so on (see
*Note partitioning-management::, for details of how to do this).

In much the same fashion, you could partition the table based on
employee job codes -- that is, based on ranges of `job_code' column
values. For example -- assuming that two-digit job codes are used for
regular (in-store) workers, three-digit codes are used for office and
support personnel, and four-digit codes are used for management
positions -- you could create the partitioned table using the following:

     CREATE TABLE employees (
         id INT NOT NULL,
         fname VARCHAR(30),
         lname VARCHAR(30),
         hired DATE NOT NULL DEFAULT '1970-01-01',
         separated DATE NOT NULL DEFAULT '9999-12-31',
         job_code INT NOT NULL,
         store_id INT NOT NULL
     )
     PARTITION BY RANGE (job_code) (
         PARTITION p0 VALUES LESS THAN (100),
         PARTITION p1 VALUES LESS THAN (1000),
         PARTITION p2 VALUES LESS THAN (10000)
     );

In this instance, all rows relating to in-store workers would be stored
in partition `p0', those relating to office and support staff in `p1',
and those relating to managers in partition `p2'.

It is also possible to use an expression in `VALUES LESS THAN' clauses.
However, MySQL must be able to evaluate the expression's return value
as part of a `LESS THAN' (`<') comparison.

Rather than splitting up the table data according to store number, you
can use an expression based on one of the two `DATE' columns instead.
For example, let us suppose that you wish to partition based on the
year that each employee left the company; that is, the value of
`YEAR(separated)'. An example of a `CREATE TABLE' statement that
implements such a partitioning scheme is shown here:

     CREATE TABLE employees (
         id INT NOT NULL,
         fname VARCHAR(30),
         lname VARCHAR(30),
         hired DATE NOT NULL DEFAULT '1970-01-01',
         separated DATE NOT NULL DEFAULT '9999-12-31',
         job_code INT,
         store_id INT
     )
     PARTITION BY RANGE ( YEAR(separated) ) (
         PARTITION p0 VALUES LESS THAN (1991),
         PARTITION p1 VALUES LESS THAN (1996),
         PARTITION p2 VALUES LESS THAN (2001),
         PARTITION p3 VALUES LESS THAN MAXVALUE
     );

In this scheme, for all employees who left before 1991, the rows are
stored in partition `p0'; for those who left in the years 1991 through
1995, in `p1'; for those who left in the years 1996 through 2000, in
`p2'; and for any workers who left after the year 2000, in `p3'.

Range partitioning is particularly useful when:

   * You want or need to delete `old' data. If you are using the
     partitioning scheme shown immediately above, you can simply use
     `ALTER TABLE employees DROP PARTITION p0;' to delete all rows
     relating to employees who stopped working for the firm prior to
     1991.  (See *Note alter-table::, and *Note
     partitioning-management::, for more information.) For a table with
     a great many rows, this can be much more efficient than running a
     `DELETE' query such as `DELETE FROM employees WHERE
     YEAR(separated) <= 1990;'.

   * You want to use a column containing date or time values, or
     containing values arising from some other series.

   * You frequently run queries that depend directly on the column used
     for partitioning the table. For example, when executing a query
     such as `EXPLAIN PARTITIONS SELECT COUNT(*) FROM employees WHERE
     separated BETWEEN '2000-01-01' AND '2000-12-31' GROUP BY
     store_id;', MySQL can quickly determine that only partition `p2'
     needs to be scanned because the remaining partitions cannot
     contain any records satisfying the `WHERE' clause. See *Note
     partitioning-pruning::, for more information about how this is
     accomplished.


File: manual.info,  Node: partitioning-list,  Next: partitioning-hash,  Prev: partitioning-range,  Up: partitioning-types

21.2.2 `LIST' Partitioning
--------------------------

List partitioning in MySQL is similar to range partitioning in many
ways. As in partitioning by `RANGE', each partition must be explicitly
defined. The chief difference is that, in list partitioning, each
partition is defined and selected based on the membership of a column
value in one of a set of value lists, rather than in one of a set of
contiguous ranges of values. This is done by using `PARTITION BY
LIST(EXPR)' where EXPR is a column value or an expression based on a
column value and returning an integer value, and then defining each
partition by means of a `VALUES IN (VALUE_LIST)', where VALUE_LIST is a
comma-separated list of integers.

*Note*:

In MySQL 5.1, it is possible to match against only a list of integers
(and possibly `NULL' -- see *Note partitioning-handling-nulls::) when
partitioning by `LIST'.

Unlike the case with partitions defined by range, list partitions do
not need to be declared in any particular order.  For more detailed
syntactical information, see *Note create-table::.

For the examples that follow, we assume that the basic definition of
the table to be partitioned is provided by the `CREATE TABLE' statement
shown here:

     CREATE TABLE employees (
         id INT NOT NULL,
         fname VARCHAR(30),
         lname VARCHAR(30),
         hired DATE NOT NULL DEFAULT '1970-01-01',
         separated DATE NOT NULL DEFAULT '9999-12-31',
         job_code INT,
         store_id INT
     );

(This is the same table used as a basis for the examples in *Note
partitioning-range::.)

Suppose that there are 20 video stores distributed among 4 franchises
as shown in the following table:

*Region*               *Store ID Numbers*
North                  3, 5, 6, 9, 17
East                   1, 2, 10, 11, 19, 20
West                   4, 12, 13, 14, 18
Central                7, 8, 15, 16

To partition this table in such a way that rows for stores belonging to
the same region are stored in the same partition, you could use the
`CREATE TABLE' statement shown here:

     CREATE TABLE employees (
         id INT NOT NULL,
         fname VARCHAR(30),
         lname VARCHAR(30),
         hired DATE NOT NULL DEFAULT '1970-01-01',
         separated DATE NOT NULL DEFAULT '9999-12-31',
         job_code INT,
         store_id INT
     )
     PARTITION BY LIST(store_id) (
         PARTITION pNorth VALUES IN (3,5,6,9,17),
         PARTITION pEast VALUES IN (1,2,10,11,19,20),
         PARTITION pWest VALUES IN (4,12,13,14,18),
         PARTITION pCentral VALUES IN (7,8,15,16)
     );

This makes it easy to add or drop employee records relating to specific
regions to or from the table. For instance, suppose that all stores in
the West region are sold to another company.  All rows relating to
employees working at stores in that region can be deleted with the
query `ALTER TABLE employees DROP PARTITION pWest;', which can be
executed much more efficiently than the equivalent `DELETE' statement
`DELETE FROM employees WHERE store_id IN (4,12,13,14,18);'.

As with `RANGE' partitioning, it is possible to combine `LIST'
partitioning with partitioning by hash or key to produce a composite
partitioning (subpartitioning). See *Note partitioning-subpartitions::.

Unlike the case with `RANGE' partitioning, there is no `catch-all' such
as `MAXVALUE'; all expected values for the partitioning expression
should be covered in `PARTITION ... VALUES IN (...)' clauses. An
`INSERT' statement containing an unmatched partitioning column value
fails with an error, as shown in this example:

     mysql> CREATE TABLE h2 (
         ->   c1 INT,
         ->   c2 INT
         -> )
         -> PARTITION BY LIST(c1) (
         ->   PARTITION p0 VALUES IN (1, 4, 7),
         ->   PARTITION p1 VALUES IN (2, 5, 8)
         -> );
     Query OK, 0 rows affected (0.11 sec)

     mysql> INSERT INTO h2 VALUES (3, 5);
     `ERROR 1525 (HY000): Table has no partition for value 3'

When inserting multiple rows using a single `INSERT' statement, any
rows coming before the row containing the unmatched value are inserted,
but any coming after it are not:

     mysql> SELECT * FROM h2;
     Empty set (0.00 sec)

     mysql> INSERT INTO h2 VALUES (4, 7), (3, 5), (6, 0);
     `ERROR 1525 (HY000): Table has no partition for value 3'
     mysql> SELECT * FROM h2;
     +------+------+
     | c1   | c2   |
     +------+------+
     |    4 |    7 |
     +------+------+
     1 row in set (0.00 sec)

You can cause this type of error to be ignored by using the `IGNORE'
key word. If you do so, rows containing unmatched partitioning column
values are not inserted, but any rows with matching values _are_
inserted, and no errors are reported:

     mysql> TRUNCATE h2;
     Query OK, 1 row affected (0.00 sec)

     mysql> SELECT * FROM h2;
     Empty set (0.00 sec)

     mysql> INSERT IGNORE INTO h2 VALUES (2, 5), (6, 10), (7, 5), (3, 1), (1, 9);
     Query OK, 3 rows affected (0.00 sec)
     Records: 5  Duplicates: 2  Warnings: 0

     mysql> SELECT * FROM h2;
     +------+------+
     | c1   | c2   |
     +------+------+
     |    7 |    5 |
     |    1 |    9 |
     |    2 |    5 |
     +------+------+
     3 rows in set (0.00 sec)


File: manual.info,  Node: partitioning-hash,  Next: partitioning-key,  Prev: partitioning-list,  Up: partitioning-types

21.2.3 `HASH' Partitioning
--------------------------

* Menu:

* partitioning-linear-hash::     `LINEAR HASH' Partitioning

Partitioning by `HASH' is used primarily to ensure an even distribution
of data among a predetermined number of partitions. With range or list
partitioning, you must specify explicitly into which partition a given
column value or set of column values is to be stored; with hash
partitioning, MySQL takes care of this for you, and you need only
specify a column value or expression based on a column value to be
hashed and the number of partitions into which the partitioned table is
to be divided.

To partition a table using `HASH' partitioning, it is necessary to
append to the `CREATE TABLE' statement a `PARTITION BY HASH (EXPR)'
clause, where EXPR is an expression that returns an integer. This can
simply be the name of a column whose type is one of MySQL's integer
types. In addition, you will most likely want to follow this with a
`PARTITIONS NUM' clause, where NUM is a non-negative integer
representing the number of partitions into which the table is to be
divided.

For example, the following statement creates a table that uses hashing
on the `store_id' column and is divided into 4 partitions:

     CREATE TABLE employees (
         id INT NOT NULL,
         fname VARCHAR(30),
         lname VARCHAR(30),
         hired DATE NOT NULL DEFAULT '1970-01-01',
         separated DATE NOT NULL DEFAULT '9999-12-31',
         job_code INT,
         store_id INT
     )
     PARTITION BY HASH(store_id)
     PARTITIONS 4;

If you do not include a `PARTITIONS' clause, the number of partitions
defaults to `1'.

Using the `PARTITIONS' keyword without a number following it results in
a syntax error.

You can also use an SQL expression that returns an integer for EXPR.
For instance, you might want to partition based on the year in which an
employee was hired. This can be done as shown here:

     CREATE TABLE employees (
         id INT NOT NULL,
         fname VARCHAR(30),
         lname VARCHAR(30),
         hired DATE NOT NULL DEFAULT '1970-01-01',
         separated DATE NOT NULL DEFAULT '9999-12-31',
         job_code INT,
         store_id INT
     )
     PARTITION BY HASH( YEAR(hired) )
     PARTITIONS 4;

You may use any function or other expression for EXPR that is valid in
MySQL, so long as it returns a non-constant, non-random integer value.
(In other words, it should be varying but deterministic.) However, you
should keep in mind that this expression is evaluated each time a row
is inserted or updated (or possibly deleted); this means that very
complex expressions may give rise to performance issues, particularly
when performing operations (such as batch inserts) that affect a great
many rows at one time.

The most efficient hashing function is one which operates upon a single
table column and whose value increases or decreases consistently with
the column value, as this allows for `pruning' on ranges of partitions.
That is, the more closely that the expression varies with the value of
the column on which it is based, the more efficiently MySQL can use the
expression for hash partitioning.

For example, where `date_col' is a column of type `DATE', then the
expression `TO_DAYS(date_col)' is said to vary directly with the value
of `date_col', because for every change in the value of `date_col', the
value of the expression changes in a consistent manner. The variance of
the expression `YEAR(date_col)' with respect to `date_col' is not quite
as direct as that of `TO_DAYS(date_col)', because not every possible
change in `date_col' produces an equivalent change in `YEAR(date_col)'.
Even so, `YEAR(date_col)' is a good candidate for a hashing function,
because it varies directly with a portion of `date_col' and there is no
possible change in `date_col' that produces a disproportionate change in
`YEAR(date_col)'.

By way of contrast, suppose that you have a column named `int_col'
whose type is `INT'.  Now consider the expression `POW(5-int_col,3) +
6'. This would be a poor choice for a hashing function because a change
in the value of `int_col' is not guaranteed to produce a proportional
change in the value of the expression. Changing the value of `int_col'
by a given amount can produce by widely different changes in the value
of the expression. For example, changing `int_col' from `5' to `6'
produces a change of `-1' in the value of the expression, but changing
the value of `int_col' from `6' to `7' produces a change of `-7' in the
expression value.

In other words, the more closely the graph of the column value _versus_
the value of the expression follows a straight line as traced by the
equation `y=Nx' where N is some nonzero constant, the better the
expression is suited to hashing. This has to do with the fact that the
more nonlinear an expression is, the more uneven the distribution of
data among the partitions it tends to produce.

In theory, pruning is also possible for expressions involving more than
one column value, but determining which of such expressions are
suitable can be quite difficult and time-consuming. For this reason,
the use of hashing expressions involving multiple columns is not
particularly recommended.

When `PARTITION BY HASH' is used, MySQL determines which partition of
NUM partitions to use based on the modulus of the result of the user
function. In other words, for an expression EXPR, the partition in
which the record is stored is partition number N, where `N = MOD(EXPR,
NUM)'. For example, suppose table `t1' is defined as follows, so that it
has 4 partitions:

     CREATE TABLE t1 (col1 INT, col2 CHAR(5), col3 DATE)
         PARTITION BY HASH( YEAR(col3) )
         PARTITIONS 4;

If you insert a record into `t1' whose `col3' value is `'2005-09-15'',
then the partition in which it is stored is determined as follows:

     MOD(YEAR('2005-09-01'),4)
     =  MOD(2005,4)
     =  1

MySQL 5.1 also supports a variant of `HASH' partitioning known as
_linear hashing_ which employs a more complex algorithm for determining
the placement of new rows inserted into the partitioned table. See
*Note partitioning-linear-hash::, for a description of this algorithm.

The user function is evaluated each time a record is inserted or
updated. It may also -- depending on the circumstances -- be evaluated
when records are deleted.

*Note*:

If a table to be partitioned has a `UNIQUE' key, then any columns
supplied as arguments to the `HASH' user function or to the `KEY''s
COLUMN_LIST must be part of that key.


File: manual.info,  Node: partitioning-linear-hash,  Prev: partitioning-hash,  Up: partitioning-hash

21.2.3.1 `LINEAR HASH' Partitioning
...................................

MySQL also supports linear hashing, which differs from regular hashing
in that linear hashing utilizes a linear powers-of-two algorithm
whereas regular hashing employs the modulus of the hashing function's
value.

Syntactically, the only difference between linear-hash partitioning and
regular hashing is the addition of the `LINEAR' keyword in the
`PARTITION BY' clause, as shown here:

     CREATE TABLE employees (
         id INT NOT NULL,
         fname VARCHAR(30),
         lname VARCHAR(30),
         hired DATE NOT NULL DEFAULT '1970-01-01',
         separated DATE NOT NULL DEFAULT '9999-12-31',
         job_code INT,
         store_id INT
     )
     PARTITION BY LINEAR HASH( YEAR(hired) )
     PARTITIONS 4;

Given an expression EXPR, the partition in which the record is stored
when linear hashing is used is partition number N from among NUM
partitions, where N is derived according to the following algorithm:

  1. Find the next power of 2 greater than NUM. We call this value V;
     it can be calculated as:

          V = POWER(2, CEILING(LOG(2, NUM)))

     (For example, suppose that NUM is 13. Then `LOG(2,13)' is
     3.7004397181411.  `CEILING(3.7004397181411)' is 4, and V =
     `POWER(2,4)', which is 16.)

  2. Set N = F(COLUMN_LIST) & (V - 1).

  3. While N >= NUM:

        * Set V = CEIL(V / 2)

        * Set N = N & (V - 1)

For example, suppose that the table `t1', using linear hash
partitioning and having 6 partitions, is created using this statement:

     CREATE TABLE t1 (col1 INT, col2 CHAR(5), col3 DATE)
         PARTITION BY LINEAR HASH( YEAR(col3) )
         PARTITIONS 6;

Now assume that you want to insert two records into `t1' having the
`col3' column values `'2003-04-14'' and `'1998-10-19''. The partition
number for the first of these is determined as follows:

     V = POWER(2, CEILING( LOG(2,6) )) = 8
     N = YEAR('2003-04-14') & (8 - 1)
        = 2003 & 7
        = 3

     (_3 >= 6 is FALSE: record stored in partition #3_)

The number of the partition where the second record is stored is
calculated as shown here:

     V = 8
     N = YEAR('1998-10-19') & (8-1)
       = 1998 & 7
       = 6

     (_6 >= 6 is TRUE: additional step required_)

     N = 6 & CEILING(8 / 2)
       = 6 & 3
       = 2

     (_2 >= 6 is FALSE: record stored in partition #2_)

The advantage in partitioning by linear hash is that the adding,
dropping, merging, and splitting of partitions is made much faster,
which can be beneficial when dealing with tables containing extremely
large amounts (terabytes) of data. The disadvantage is that data is
less likely to be evenly distributed between partitions as compared
with the distribution obtained using regular hash partitioning.


File: manual.info,  Node: partitioning-key,  Next: partitioning-subpartitions,  Prev: partitioning-hash,  Up: partitioning-types

21.2.4 `KEY' Partitioning
-------------------------

Partitioning by key is similar to partitioning by hash, except that
where hash partitioning employs a user-defined expression, the hashing
function for key partitioning is supplied by the MySQL server. MySQL
Cluster uses `MD5()' for this purpose; for tables using other storage
engines, the server employs its own internal hashing function which is
based on the same algorithm as `PASSWORD()'.

The syntax rules for `CREATE TABLE ... PARTITION BY KEY' are similar to
those for creating a table that is partitioned by hash. The major
differences are that:

   * `KEY' is used rather than `HASH'.

   * `KEY' takes only a list of one or more column names. Beginning
     with MySQL 5.1.5, the column or columns used as the partitioning
     key must comprise part or all of the table's primary key, if the
     table has one.

     Beginning with MySQL 5.1.6, `KEY' takes a list of zero or more
     column names. Where no column name is specified as the
     partitioning key, the table's primary key is used, if there is
     one. For example, the following `CREATE TABLE' statement is valid
     in MySQL 5.1.6 or later:

          CREATE TABLE k1 (
              id INT NOT NULL PRIMARY KEY,
              name VARCHAR(20)
          )
          PARTITION BY KEY()
          PARTITIONS 2;

     If there is no primary key but there is a unique key, then the
     unique key is used for the partitioning key:

          CREATE TABLE k1 (
              id INT NOT NULL,
              name VARCHAR(20),
              UNIQUE KEY (id)
          )
          PARTITION BY KEY()
          PARTITIONS 2;

     However, if the unique key column were not defined as `NOT NULL',
     then the previous statement would fail.

     In both of these cases, the partitioning key is the `id' column,
     even though it is not shown in the output of `SHOW CREATE TABLE'
     or in the `PARTITION_EXPRESSION' column of the
     `INFORMATION_SCHEMA.PARTITIONS' table.

     Unlike the case with other partitioning types, columns used for
     partitioning by `KEY' are not restricted to integer or `NULL'
     values. For example, the following `CREATE TABLE' statement is
     valid:

          CREATE TABLE tm1 (
              s1 CHAR(32) PRIMARY KEY
          )
          PARTITION BY KEY(s1)
          PARTITIONS 10;

     The preceding statement would _not_ be valid, were a different
     partitioning type to be specified.

     *Note*:

     In this case, simply using `PARTITION BY KEY()' would also be
     valid and have the same effect as `PARTITION BY KEY(s1)', since
     `s1' is the table's primary key.

     For additional information about this issue, see *Note
     partitioning-limitations::.

     *Note*:

     Also beginning with MySQL 5.1.6, tables using the `NDBCLUSTER'
     storage engine are implicitly partitioned by `KEY', again using
     the table's primary key as the partitioning key. In the event that
     the Cluster table has no explicit primary key, the `hidden'
     primary key generated by the `NDBCLUSTER' storage engine for each
     MySQL Cluster table is used as the partitioning key.

     *Important*:

     For a key-partitioned table using any MySQL storage engine other
     than `NDBCLUSTER', you cannot execute an `ALTER TABLE DROP PRIMARY
     KEY', as doing so generates the error `ERROR 1466 (HY000): Field
     in list of fields for partition function not found in table'. This
     is not an issue for MySQL Cluster tables which are partitioned by
     `KEY'; in such cases, the table is reorganized using the `hidden'
     primary key as the table's new partitioning key. See *Note
     mysql-cluster::.

It is also possible to partition a table by linear key. Here is a
simple example:

     CREATE TABLE tk (
         col1 INT NOT NULL,
         col2 CHAR(5),
         col3 DATE
     )
     PARTITION BY LINEAR KEY (col1)
     PARTITIONS 3;

Using `LINEAR' has the same effect on `KEY' partitioning as it does on
`HASH' partitioning, with the partition number being derived using a
powers-of-two algorithm rather than modulo arithmetic. See *Note
partitioning-linear-hash::, for a description of this algorithm and its
implications.


File: manual.info,  Node: partitioning-subpartitions,  Next: partitioning-handling-nulls,  Prev: partitioning-key,  Up: partitioning-types

21.2.5 Subpartitioning
----------------------

Subpartitioning -- also known as _composite partitioning_ -- is the
further division of each partition in a partitioned table. For example,
consider the following `CREATE TABLE' statement:

     CREATE TABLE ts (id INT, purchased DATE)
         PARTITION BY RANGE( YEAR(purchased) )
         SUBPARTITION BY HASH( TO_DAYS(purchased) )
         SUBPARTITIONS 2 (
             PARTITION p0 VALUES LESS THAN (1990),
             PARTITION p1 VALUES LESS THAN (2000),
             PARTITION p2 VALUES LESS THAN MAXVALUE
         );

Table `ts' has 3 `RANGE' partitions. Each of these partitions -- `p0',
`p1', and `p2' -- is further divided into 2 subpartitions. In effect,
the entire table is divided into `3 * 2 = 6' partitions. However, due
to the action of the `PARTITION BY RANGE' clause, the first 2 of these
store only those records with a value less than 1990 in the `purchased'
column.

In MySQL 5.1, it is possible to subpartition tables that are
partitioned by `RANGE' or `LIST'. Subpartitions may use either `HASH'
or `KEY' partitioning.  This is also known as _composite partitioning_.

It is also possible to define subpartitions explicitly using
`SUBPARTITION' clauses to specify options for individual subpartitions.
For example, a more verbose fashion of creating the same table `ts' as
shown in the previous example would be:

     CREATE TABLE ts (id INT, purchased DATE)
         PARTITION BY RANGE( YEAR(purchased) )
         SUBPARTITION BY HASH( TO_DAYS(purchased) ) (
             PARTITION p0 VALUES LESS THAN (1990) (
                 SUBPARTITION s0,
                 SUBPARTITION s1
             ),
             PARTITION p1 VALUES LESS THAN (2000) (
                 SUBPARTITION s2,
                 SUBPARTITION s3
             ),
             PARTITION p2 VALUES LESS THAN MAXVALUE (
                 SUBPARTITION s4,
                 SUBPARTITION s5
             )
         );

Some syntactical items of note:

   * Each partition must have the same number of subpartitions.

   * If you explicitly define any subpartitions using `SUBPARTITION' on
     any partition of a partitioned table, you must define them all. In
     other words, the following statement will fail:

          CREATE TABLE ts (id INT, purchased DATE)
              PARTITION BY RANGE( YEAR(purchased) )
              SUBPARTITION BY HASH( TO_DAYS(purchased) ) (
                  PARTITION p0 VALUES LESS THAN (1990) (
                      SUBPARTITION s0,
                      SUBPARTITION s1
                  ),
                  PARTITION p1 VALUES LESS THAN (2000),
                  PARTITION p2 VALUES LESS THAN MAXVALUE (
                      SUBPARTITION s2,
                      SUBPARTITION s3
                  )
              );

     This statement would still fail even if it included a
     `SUBPARTITIONS 2' clause.

   * Each `SUBPARTITION' clause must include (at a minimum) a name for
     the subpartition. Otherwise, you may set any desired option for
     the subpartition or allow it to assume its default setting for
     that option.

   * In MySQL 5.1.7 and earlier, names of subpartitions were required
     to be unique within each partition, but did not have to be unique
     within the table as a whole. Beginning with MySQL 5.1.8,
     subpartition names must be unique across the entire table. For
     example, the following `CREATE TABLE' statement is valid in MySQL
     5.1.8 and later:

          CREATE TABLE ts (id INT, purchased DATE)
              PARTITION BY RANGE( YEAR(purchased) )
              SUBPARTITION BY HASH( TO_DAYS(purchased) ) (
                  PARTITION p0 VALUES LESS THAN (1990) (
                      SUBPARTITION s0,
                      SUBPARTITION s1
                  ),
                  PARTITION p1 VALUES LESS THAN (2000) (
                      SUBPARTITION s2,
                      SUBPARTITION s3
                  ),
                  PARTITION p2 VALUES LESS THAN MAXVALUE (
                      SUBPARTITION s4,
                      SUBPARTITION s5
                  )
              );

     (The previous statement is also valid for versions of MySQL prior
     to 5.1.8.)

Subpartitions can be used with especially large tables to distribute
data and indexes across many disks. Suppose that you have 6 disks
mounted as `/disk0', `/disk1', `/disk2', and so on. Now consider the
following example:

     CREATE TABLE ts (id INT, purchased DATE)
         PARTITION BY RANGE( YEAR(purchased) )
         SUBPARTITION BY HASH( TO_DAYS(purchased) ) (
             PARTITION p0 VALUES LESS THAN (1990) (
                 SUBPARTITION s0
                     DATA DIRECTORY = '/disk0/data'
                     INDEX DIRECTORY = '/disk0/idx',
                 SUBPARTITION s1
                     DATA DIRECTORY = '/disk1/data'
                     INDEX DIRECTORY = '/disk1/idx'
             ),
             PARTITION p1 VALUES LESS THAN (2000) (
                 SUBPARTITION s2
                     DATA DIRECTORY = '/disk2/data'
                     INDEX DIRECTORY = '/disk2/idx',
                 SUBPARTITION s3
                     DATA DIRECTORY = '/disk3/data'
                     INDEX DIRECTORY = '/disk3/idx'
             ),
             PARTITION p2 VALUES LESS THAN MAXVALUE (
                 SUBPARTITION s4
                     DATA DIRECTORY = '/disk4/data'
                     INDEX DIRECTORY = '/disk4/idx',
                 SUBPARTITION s5
                     DATA DIRECTORY = '/disk5/data'
                     INDEX DIRECTORY = '/disk5/idx'
             )
         );

In this case, a separate disk is used for the data and for the indexes
of each `RANGE'. Many other variations are possible; another example
might be:

     CREATE TABLE ts (id INT, purchased DATE)
         PARTITION BY RANGE(YEAR(purchased))
         SUBPARTITION BY HASH( TO_DAYS(purchased) ) (
             PARTITION p0 VALUES LESS THAN (1990) (
                 SUBPARTITION s0a
                     DATA DIRECTORY = '/disk0'
                     INDEX DIRECTORY = '/disk1',
                 SUBPARTITION s0b
                     DATA DIRECTORY = '/disk2'
                     INDEX DIRECTORY = '/disk3'
             ),
             PARTITION p1 VALUES LESS THAN (2000) (
                 SUBPARTITION s1a
                     DATA DIRECTORY = '/disk4/data'
                     INDEX DIRECTORY = '/disk4/idx',
                 SUBPARTITION s1b
                     DATA DIRECTORY = '/disk5/data'
                     INDEX DIRECTORY = '/disk5/idx'
             ),
             PARTITION p2 VALUES LESS THAN MAXVALUE (
                 SUBPARTITION s2a,
                 SUBPARTITION s2b
             )
         );

Here, the storage is as follows:

   * Rows with `purchased' dates from before 1990 take up a vast amount
     of space, so are split up 4 ways, with a separate disk dedicated
     to the data and to the indexes for each of the two subpartitions
     (`s0a' and `s0b') making up partition `p0'. In other words:

        * The data for subpartition `s0a' is stored on `/disk0'.

        * The indexes for subpartition `s0a' are stored on `/disk1'.

        * The data for subpartition `s0b' is stored on `/disk2'.

        * The indexes for subpartition `s0b' are stored on `/disk3'.

   * Rows containing dates ranging from 1990 to 1999 (partition `p1')
     do not require as much room as those from before 1990. These are
     split between 2 disks (`/disk4' and `/disk5') rather than 4 disks
     as with the legacy records stored in `p0':

        * Data and indexes belonging to `p1''s first subpartition
          (`s1a') are stored on `/disk4' -- the data in `/disk4/data',
          and the indexes in `/disk4/idx'.

        * Data and indexes belonging to `p1''s second subpartition
          (`s1b') are stored on `/disk5' -- the data in `/disk5/data',
          and the indexes in `/disk5/idx'.

   * Rows reflecting dates from the year 2000 to the present (partition
     `p2') do not take up as much space as required by either of the
     two previous ranges.  Currently, it is sufficient to store all of
     these in the default location.

     In future, when the number of purchases for the decade beginning
     with the year 2000 grows to a point where the default location no
     longer provides sufficient space, the corresponding rows can be
     moved using an `ALTER TABLE ... REORGANIZE PARTITION' statement.
     See *Note partitioning-management::, for an explanation of how
     this can be done.

Beginning with MySQL 5.1.18, the `DATA DIRECTORY' and `INDEX DIRECTORY'
options are disallowed when the `NO_DIR_IN_CREATE' server SQL mode is in
effect. This is true for partitions and subpartitions.


File: manual.info,  Node: partitioning-handling-nulls,  Prev: partitioning-subpartitions,  Up: partitioning-types

21.2.6 How MySQL Partitioning Handles `NULL' Values
---------------------------------------------------

Partitioning in MySQL does nothing to disallow `NULL' as the value of a
partitioning expression, whether it is a column value or the value of a
user-supplied expression. Even though it is permitted to use `NULL' as
the value of an expression that must otherwise yield an integer, it is
important to keep in mind that `NULL' is not a number. Beginning with
MySQL 5.1.8, the partitioning implementation treats `NULL' as being
less than any non-`NULL' value, just as `ORDER BY' does.

This means that treatment of `NULL' varies between partitioning of
different types, and may produce behavior which you do not expect if
you are not prepared for it.  This being the case, we discuss in this
section how each MySQL partitioning type handles `NULL' values when
determining the partition in which a row should be stored, and provide
examples for each.

Handling of `NULL' with `RANGE' partitioning

If you insert a row into a table partitioned by `RANGE' such that the
column value used to determine the partition is `NULL', the row is
inserted into the lowest partition. For example, consider these two
tables in a database named `p', created as follows:

     mysql> CREATE TABLE t1 (
         ->     c1 INT,
         ->     c2 VARCHAR(20)
         -> )
         -> PARTITION BY RANGE(c1) (
         ->     PARTITION p0 VALUES LESS THAN (0),
         ->     PARTITION p1 VALUES LESS THAN (10),
         ->     PARTITION p2 VALUES LESS THAN MAXVALUE
         -> );
     Query OK, 0 rows affected (0.09 sec)

     mysql> CREATE TABLE t2 (
         ->     c1 INT,
         ->     c2 VARCHAR(20)
         -> )
         -> PARTITION BY RANGE(c1) (
         ->     PARTITION p0 VALUES LESS THAN (-5),
         ->     PARTITION p1 VALUES LESS THAN (0),
         ->     PARTITION p2 VALUES LESS THAN (10),
         ->     PARTITION p3 VALUES LESS THAN MAXVALUE
         -> );
     Query OK, 0 rows affected (0.09 sec)

You can see the partitions created by these two `CREATE TABLE'
statements using the following query against the `PARTITIONS' table in
the `INFORMATION_SCHEMA' database:

     mysql> SELECT TABLE_NAME, PARTITION_NAME, TABLE_ROWS, AVG_ROW_LENGTH, DATA_LENGTH
          >   FROM INFORMATION_SCHEMA.PARTITIONS
          >   WHERE TABLE_SCHEMA = 'p' AND TABLE_NAME LIKE 't_';
     +------------+----------------+------------+----------------+-------------+
     | TABLE_NAME | PARTITION_NAME | TABLE_ROWS | AVG_ROW_LENGTH | DATA_LENGTH |
     +------------+----------------+------------+----------------+-------------+
     | t1         | p0             |          0 |              0 |           0 |
     | t1         | p1             |          0 |              0 |           0 |
     | t1         | p2             |          0 |              0 |           0 |
     | t2         | p0             |          0 |              0 |           0 |
     | t2         | p1             |          0 |              0 |           0 |
     | t2         | p2             |          0 |              0 |           0 |
     | t2         | p3             |          0 |              0 |           0 |
     +------------+----------------+------------+----------------+-------------+
     7 rows in set (0.00 sec)

(For more information about this table, see *Note partitions-table::.)
Now let us populate each of these tables with a single row containing a
`NULL' in the column used as the partitioning key, and verify that the
rows were inserted using a pair of `SELECT' statements:

     mysql> INSERT INTO t1 VALUES (NULL, 'mothra');
     Query OK, 1 row affected (0.00 sec)

     mysql> INSERT INTO t2 VALUES (NULL, 'mothra');
     Query OK, 1 row affected (0.00 sec)

     mysql> SELECT * FROM t1;
     +------+--------+
     | id   | name   |
     +------+--------+
     | NULL | mothra |
     +------+--------+
     1 row in set (0.00 sec)

     mysql> SELECT * FROM t2;
     +------+--------+
     | id   | name   |
     +------+--------+
     | NULL | mothra |
     +------+--------+
     1 row in set (0.00 sec)

You can see which partitions are used to store the inserted rows by
rerunning the previous query against `INFORMATION_SCHEMA.PARTITIONS' and
inspecting the output:

     mysql> SELECT TABLE_NAME, PARTITION_NAME, TABLE_ROWS, AVG_ROW_LENGTH, DATA_LENGTH
          >   FROM INFORMATION_SCHEMA.PARTITIONS
          >   WHERE TABLE_SCHEMA = 'p' AND TABLE_NAME LIKE 't_';
     +------------+----------------+------------+----------------+-------------+
     | TABLE_NAME | PARTITION_NAME | TABLE_ROWS | AVG_ROW_LENGTH | DATA_LENGTH |
     +------------+----------------+------------+----------------+-------------+
     _| t1         | p0             |          1 |             20 |          20 |_
     | t1         | p1             |          0 |              0 |           0 |
     | t1         | p2             |          0 |              0 |           0 |
     _| t2         | p0             |          1 |             20 |          20 |_
     | t2         | p1             |          0 |              0 |           0 |
     | t2         | p2             |          0 |              0 |           0 |
     | t2         | p3             |          0 |              0 |           0 |
     +------------+----------------+------------+----------------+-------------+
     7 rows in set (0.01 sec)

You can also demonstrate that these rows were stored in the lowest
partition of each table by dropping these partitions, and then
re-running the `SELECT' statements:

     mysql> ALTER TABLE t1 DROP PARTITION p0;
     Query OK, 0 rows affected (0.16 sec)

     mysql> ALTER TABLE t2 DROP PARTITION p0;
     Query OK, 0 rows affected (0.16 sec)

     mysql> SELECT * FROM t1;
     Empty set (0.00 sec)

     mysql> SELECT * FROM t2;
     Empty set (0.00 sec)

(For more information on `ALTER TABLE ... DROP PARTITION', see *Note
alter-table::.)

*Important*:

Prior to MySQL 5.1.8, `RANGE' partitioning treated a partitioning
expression value of `NULL' as 0 with respect to determining placement.
(The only way to circumvent this behavior was to design tables so as
not to allow nulls, usually by declaring columns `NOT NULL'.) If you
have a `RANGE' partitioning scheme that depends on this earlier
behavior, you must re-implement it when upgrading to MySQL 5.1.8 or
later. (Bug#15447 (http://bugs.mysql.com/15447))

`NULL' is also treated in this way for partitioning expressions that
use SQL functions. Suppose that we define a table using a `CREATE
TABLE' statement such as this one:

     CREATE TABLE tndate (
         id INT,
         dt DATE
     )
     PARTITION BY RANGE( YEAR(dt) ) (
         PARTITION p0 VALUES LESS THAN (1990),
         PARTITION p1 VALUES LESS THAN (2000),
         PARTITION p2 VALUES LESS THAN MAXVALUE
     );

As with other MySQL functions, `YEAR(NULL)' returns `NULL'. A row with
a `dt' column value of `NULL' is treated as though the partitioning
expression evaluated to a value less than any other value, and so is
inserted into partition `p0'.

Handling of `NULL' with `LIST' partitioning

A table that is partitioned by `LIST' admits `NULL' values if and only
if one of its partitions is defined using that value-list that contains
`NULL'. The converse of this is that a table partitioned by `LIST'
which does not explicitly use `NULL' in a value list rejects rows
resulting in a `NULL' value for the partitioning expression, as shown
in this example:

     mysql> CREATE TABLE ts1 (
         ->     c1 INT,
         ->     c2 VARCHAR(20)
         -> )
         -> PARTITION BY LIST(c1) (
         ->     PARTITION p0 VALUES IN (0, 3, 6),
         ->     PARTITION p1 VALUES IN (1, 4, 7),
         ->     PARTITION p2 VALUES IN (2, 5, 8)
         -> );
     Query OK, 0 rows affected (0.01 sec)

     mysql> INSERT INTO ts1 VALUES (9, 'mothra');
     `ERROR 1504 (HY000): Table has no partition for value 9'

     mysql> INSERT INTO ts1 VALUES (NULL, 'mothra');
     `ERROR 1504 (HY000): Table has no partition for value NULL'

Only rows having a `c1' value between `0' and `8' inclusive can be
inserted into `ts1'. `NULL' falls outside this range, just like the
number `9'. We can create tables `ts2' and `ts3' having value lists
containing `NULL', as shown here:

     mysql> CREATE TABLE ts2 (
         ->     c1 INT,
         ->     c2 VARCHAR(20)
         -> )
         -> PARTITION BY LIST(c1) (
         ->     PARTITION p0 VALUES IN (0, 3, 6),
         ->     PARTITION p1 VALUES IN (1, 4, 7),
         ->     PARTITION p2 VALUES IN (2, 5, 8),
         ->     PARTITION p3 VALUES IN (NULL)
         -> );
     Query OK, 0 rows affected (0.01 sec)

     mysql> CREATE TABLE ts3 (
         ->     c1 INT,
         ->     c2 VARCHAR(20)
         -> )
         -> PARTITION BY LIST(c1) (
         ->     PARTITION p0 VALUES IN (0, 3, 6),
         ->     PARTITION p1 VALUES IN (1, 4, 7, NULL),
         ->     PARTITION p2 VALUES IN (2, 5, 8)
         -> );
     Query OK, 0 rows affected (0.01 sec)

When defining value lists for partitioning, you can (and should) treat
`NULL' just as you would any other value. For example, both `VALUES IN
(NULL)' and `VALUES IN (1, 4, 7, NULL)' are valid, as are `VALUES IN
(1, NULL, 4, 7)', `VALUES IN (NULL, 1, 4, 7)', and so on. You can
insert a row having `NULL' for column `c1' into each of the tables
`ts2' and `ts3':

     mysql> INSERT INTO ts2 VALUES (NULL, 'mothra');
     Query OK, 1 row affected (0.00 sec)

     mysql> INSERT INTO ts3 VALUES (NULL, 'mothra');
     Query OK, 1 row affected (0.00 sec)

By issuing the appropriate query against
`INFORMATION_SCHEMA.PARTITIONS', you can determine which partitions
were used to store the rows just inserted (we assume, as in the
previous examples, that the partitioned tables were created in the `p'
database):

     mysql> SELECT TABLE_NAME, PARTITION_NAME, TABLE_ROWS, AVG_ROW_LENGTH, DATA_LENGTH
          >   FROM INFORMATION_SCHEMA.PARTITIONS
          >   WHERE TABLE_SCHEMA = 'p' AND TABLE_NAME LIKE 'ts_';
     +------------+----------------+------------+----------------+-------------+
     | TABLE_NAME | PARTITION_NAME | TABLE_ROWS | AVG_ROW_LENGTH | DATA_LENGTH |
     +------------+----------------+------------+----------------+-------------+
     | ts2        | p0             |          0 |              0 |           0 |
     | ts2        | p1             |          0 |              0 |           0 |
     | ts2        | p2             |          0 |              0 |           0 |
     _| ts2        | p3             |          1 |             20 |          20 |_
     | ts3        | p0             |          0 |              0 |           0 |
     _| ts3        | p1             |          1 |             20 |          20 |_
     | ts3        | p2             |          0 |              0 |           0 |
     +------------+----------------+------------+----------------+-------------+
     7 rows in set (0.01 sec)

As shown earlier in this section, you can also verify which partitions
were used for storing the rows by deleting these partitions and then
performing a `SELECT'.

Handling of `NULL' with `HASH' and `KEY' partitioning

`NULL' is handled somewhat differently for tables partitioned by `HASH'
or `KEY'. In these cases, any partition expression that yields a `NULL'
value is treated as though its return value were zero. We can verify
this behavior by examining the effects on the filesystem of creating a
table partitioned by `HASH' and populating it with a record containing
appropriate values.  Suppose that you have a table `th' (also in the
`p' database) created using the following statement:

     mysql> CREATE TABLE th (
         ->     c1 INT,
         ->     c2 VARCHAR(20)
         -> )
         -> PARTITION BY HASH(c1)
         -> PARTITIONS 2;
     Query OK, 0 rows affected (0.00 sec)

The partitions belonging to this table can be viewed like this:

     mysql> SELECT TABLE_NAME,PARTITION_NAME,TABLE_ROWS,AVG_ROW_LENGTH,DATA_LENGTH
          >   FROM INFORMATION_SCHEMA.PARTITIONS
          >   WHERE TABLE_SCHEMA = 'p' AND TABLE_NAME ='th';
     +------------+----------------+------------+----------------+-------------+
     | TABLE_NAME | PARTITION_NAME | TABLE_ROWS | AVG_ROW_LENGTH | DATA_LENGTH |
     +------------+----------------+------------+----------------+-------------+
     | th         | p0             |          0 |              0 |           0 |
     | th         | p1             |          0 |              0 |           0 |
     +------------+----------------+------------+----------------+-------------+
     2 rows in set (0.00 sec)

Note that TABLE_ROWS for each partition is 0. Now insert two rows into
`th' whose `c1' column values are `NULL' and 0, and verify that these
rows were inserted:

     mysql> INSERT INTO th VALUES (NULL, 'mothra'), (0, 'gigan');
     Query OK, 1 row affected (0.00 sec)

     mysql> SELECT * FROM th;
     +------+---------+
     | c1   | c2      |
     +------+---------+
     | NULL | mothra  |
     +------+---------+
     |    0 | gigan   |
     +------+---------+
     2 rows in set (0.01 sec)

Recall that for any integer N, the value of `NULL MOD N' is always
`NULL'. For tables that are partitioned by `HASH' or `KEY', this result
is treated for determining the correct partition as `0'. Checking the
`INFORMATION_SCHEMA.PARTITIONS' table once again, we can see that both
rows were inserted into partition `p0':

     mysql> SELECT TABLE_NAME, PARTITION_NAME, TABLE_ROWS, AVG_ROW_LENGTH, DATA_LENGTH
          >   FROM INFORMATION_SCHEMA.PARTITIONS
          >   WHERE TABLE_SCHEMA = 'p' AND TABLE_NAME ='th';
     +------------+----------------+------------+----------------+-------------+
     | TABLE_NAME | PARTITION_NAME | TABLE_ROWS | AVG_ROW_LENGTH | DATA_LENGTH |
     +------------+----------------+------------+----------------+-------------+
     _| th         | p0             |          2 |             20 |          20 |_
     | th         | p1             |          0 |              0 |           0 |
     +------------+----------------+------------+----------------+-------------+
     2 rows in set (0.00 sec)

If you repeat this example using `PARTITION BY KEY' in place of
`PARTITION BY HASH' in the definition of the table, you can verify
easily that `NULL' is also treated like 0 for this type of partitioning
as well.


File: manual.info,  Node: partitioning-management,  Next: partitioning-pruning,  Prev: partitioning-types,  Up: partitioning

21.3 Partition Management
=========================

* Menu:

* partitioning-management-range-list::  Management of `RANGE' and `LIST' Partitions
* partitioning-management-hash-key::  Management of `HASH' and `KEY' Partitions
* partitioning-maintenance::     Maintenance of Partitions
* partitioning-info::            Obtaining Information About Partitions

MySQL 5.1 provides a number of ways to modify partitioned tables. It is
possible to add, drop, redefine, merge, or split existing partitions.
All of these actions can be carried out using the partitioning
extensions to the `ALTER TABLE' command (see *Note alter-table::, for
syntax definitions). There are also ways to obtain information about
partitioned tables and partitions. We discuss these topics in the
sections that follow.

   * For information about partition management in tables partitioned
     by `RANGE' or `LIST', see *Note
     partitioning-management-range-list::.

   * For a discussion of managing `HASH' and `KEY' partitions, see
     *Note partitioning-management-hash-key::.

   * See *Note partitioning-info::, for a discussion of mechanisms
     provided in MySQL 5.1 for obtaining information about partitioned
     tables and partitions.

   * For a discussion of performing maintenance operations on
     partitions, see *Note partitioning-maintenance::.

*Note*:

In MySQL 5.1, all partitions of a partitioned table must have the same
number of subpartitions, and it is not possible to change the
subpartitioning once the table has been created.

The statement `ALTER TABLE ... PARTITION BY ...' is available and is
functional beginning with MySQL 5.1.6; previously in MySQL 5.1, this
was accepted as valid syntax, but the statement did nothing.

To change a table's partitioning scheme, it is necessary only to use
the `ALTER TABLE' command with a PARTITION_OPTIONS clause. This clause
has the same syntax as that as used with `CREATE TABLE' for creating a
partitioned table, and always begins with the keywords `PARTITION BY'.
For example, suppose that you have a table partitioned by range using
the following `CREATE TABLE' statement:

     CREATE TABLE trb3 (id INT, name VARCHAR(50), purchased DATE)
         PARTITION BY RANGE( YEAR(purchased) ) (
             PARTITION p0 VALUES LESS THAN (1990),
             PARTITION p1 VALUES LESS THAN (1995),
             PARTITION p2 VALUES LESS THAN (2000),
             PARTITION p3 VALUES LESS THAN (2005)
         );

To repartition this table so that it is partitioned by key into two
partitions using the `id' column value as the basis for the key, you
can use this statement:

     ALTER TABLE trb3 PARTITION BY KEY(id) PARTITIONS 2;

This has the same effect on the structure of the table as dropping the
table and re-creating it using `CREATE TABLE trb3 PARTITION BY KEY(id)
PARTITIONS 2;'.

In MySQL 5.1.7 and earlier MySQL 5.1 releases, `ALTER TABLE ... ENGINE
= ...' removed all partitioning from the affected table. Beginning with
MySQL 5.1.8, this statement changes only the storage engine used by the
table, and leaves the table's partitioning scheme intact. As of MySQL
5.1.8, use `ALTER TABLE ... REMOVE PARTITIONING' to remove a table's
partitioning. See *Note alter-table::.

*Important*:

Only a single `PARTITION BY', `ADD PARTITION', `DROP PARTITION',
`REORGANIZE PARTITION', or `COALESCE PARTITION' clause can be used in a
given `ALTER TABLE' statement. If you (for example) wish to drop a
partition and reorganize a table's remaining partitions, you must do so
in two separate `ALTER TABLE' statements (one using `DROP PARTITION'
and then a second one using `REORGANIZE PARITITIONS').


File: manual.info,  Node: partitioning-management-range-list,  Next: partitioning-management-hash-key,  Prev: partitioning-management,  Up: partitioning-management

21.3.1 Management of `RANGE' and `LIST' Partitions
--------------------------------------------------

Range and list partitions are very similar with regard to how the
adding and dropping of partitions are handled. For this reason we
discuss the management of both sorts of partitioning in this section.
For information about working with tables that are partitioned by hash
or key, see *Note partitioning-management-hash-key::. Dropping a
`RANGE' or `LIST' partition is more straightforward than adding one, so
we discuss this first.

Dropping a partition from a table that is partitioned by either `RANGE'
or by `LIST' can be accomplished using the `ALTER TABLE' statement with
a `DROP PARTITION' clause. Here is a very basic example, which supposes
that you have already created a table which is partitioned by range and
then populated with 10 records using the following `CREATE TABLE' and
`INSERT' statements:

     mysql> CREATE TABLE tr (id INT, name VARCHAR(50), purchased DATE)
         ->     PARTITION BY RANGE( YEAR(purchased) ) (
         ->         PARTITION p0 VALUES LESS THAN (1990),
         ->         PARTITION p1 VALUES LESS THAN (1995),
         ->         PARTITION p2 VALUES LESS THAN (2000),
         ->         PARTITION p3 VALUES LESS THAN (2005)
         ->     );
     Query OK, 0 rows affected (0.01 sec)

     mysql> INSERT INTO tr VALUES
         ->     (1, 'desk organiser', '2003-10-15'),
         ->     (2, 'CD player', '1993-11-05'),
         ->     (3, 'TV set', '1996-03-10'),
         ->     (4, 'bookcase', '1982-01-10'),
         ->     (5, 'exercise bike', '2004-05-09'),
         ->     (6, 'sofa', '1987-06-05'),
         ->     (7, 'popcorn maker', '2001-11-22'),
         ->     (8, 'aquarium', '1992-08-04'),
         ->     (9, 'study desk', '1984-09-16'),
         ->     (10, 'lava lamp', '1998-12-25');
     Query OK, 10 rows affected (0.01 sec)

You can see which items should have been inserted into partition `p2'
as shown here:

     mysql> SELECT * FROM tr
         -> WHERE purchased BETWEEN '1995-01-01' AND '1999-12-31';
     +------+-----------+------------+
     | id   | name      | purchased  |
     +------+-----------+------------+
     |    3 | TV set    | 1996-03-10 |
     |   10 | lava lamp | 1998-12-25 |
     +------+-----------+------------+
     2 rows in set (0.00 sec)

To drop the partition named `p2', execute the following command:

     mysql> ALTER TABLE tr DROP PARTITION p2;
     Query OK, 0 rows affected (0.03 sec)

*Note*:

The `NDBCLUSTER' storage engine does not support `ALTER TABLE ... DROP
PARTITION'. It does, however, support the other partitioning-related
extensions to `ALTER TABLE' that are described in this chapter.

It is very important to remember that, _when you drop a partition, you
also delete all the data that was stored in that partition_. You can
see that this is the case by re-running the previous `SELECT' query:

     mysql> SELECT * FROM tr WHERE purchased
         -> BETWEEN '1995-01-01' AND '1999-12-31';
     Empty set (0.00 sec)

Because of this, the requirement was added in MySQL 5.1.10 that you
have the `DROP' privilege for a table before you can execute `ALTER
TABLE ... DROP PARTITION' on that table.

If you wish to drop all data from all partitions while preserving the
table definition and its partitioning scheme, use the `TRUNCATE TABLE'
command. (See *Note truncate::.)

If you intend to change the partitioning of a table _without_ losing
data, use `ALTER TABLE ... REORGANIZE PARTITION' instead. See below or
in *Note alter-table::, for information about `REORGANIZE PARTITION'.

If you now execute a `SHOW CREATE TABLE' command, you can see how the
partitioning makeup of the table has been changed:

     mysql> SHOW CREATE TABLE tr\G
     *************************** 1. row ***************************
            Table: tr
     Create Table: CREATE TABLE `tr` (
       `id` int(11) default NULL,
       `name` varchar(50) default NULL,
       `purchased` date default NULL
     ) ENGINE=MyISAM DEFAULT CHARSET=latin1
     PARTITION BY RANGE ( YEAR(purchased) ) (
       PARTITION p0 VALUES LESS THAN (1990) ENGINE = MyISAM,
       PARTITION p1 VALUES LESS THAN (1995) ENGINE = MyISAM,
       PARTITION p3 VALUES LESS THAN (2005) ENGINE = MyISAM
     )
     1 row in set (0.01 sec)

When you insert new rows into the changed table with `purchased' column
values between `'1995-01-01'' and `'2004-12-31'' inclusive, those rows
will be stored in partition `p3'. You can verify this as follows:

     mysql> INSERT INTO tr VALUES (11, 'pencil holder', '1995-07-12');
     Query OK, 1 row affected (0.00 sec)

     mysql> SELECT * FROM tr WHERE purchased
         -> BETWEEN '1995-01-01' AND '2004-12-31';
     +------+----------------+------------+
     | id   | name           | purchased  |
     +------+----------------+------------+
     |   11 | pencil holder  | 1995-07-12 |
     |    1 | desk organiser | 2003-10-15 |
     |    5 | exercise bike  | 2004-05-09 |
     |    7 | popcorn maker  | 2001-11-22 |
     +------+----------------+------------+
     4 rows in set (0.00 sec)

     mysql> ALTER TABLE tr DROP PARTITION p3;
     Query OK, 0 rows affected (0.03 sec)

     mysql> SELECT * FROM tr WHERE purchased
         -> BETWEEN '1995-01-01' AND '2004-12-31';
     Empty set (0.00 sec)

Note that the number of rows dropped from the table as a result of
`ALTER TABLE ... DROP PARTITION' is not reported by the server as it
would be by the equivalent `DELETE' query.

Dropping `LIST' partitions uses exactly the same `ALTER TABLE ... DROP
PARTITION' syntax as used for dropping `RANGE' partitions. However,
there is one important difference in the effect this has on your use of
the table afterward: You can no longer insert into the table any rows
having any of the values that were included in the value list defining
the deleted partition. (See *Note partitioning-list::, for an example.)

To add a new range or list partition to a previously partitioned table,
use the `ALTER TABLE ... ADD PARTITION' statement. For tables which are
partitioned by `RANGE', this can be used to add a new range to the end
of the list of existing partitions. For example, suppose that you have
a partitioned table containing membership data for your organisation,
which is defined as follows:

     CREATE TABLE members (
         id INT,
         fname VARCHAR(25),
         lname VARCHAR(25),
         dob DATE
     )
     PARTITION BY RANGE( YEAR(dob) ) (
         PARTITION p0 VALUES LESS THAN (1970),
         PARTITION p1 VALUES LESS THAN (1980),
         PARTITION p2 VALUES LESS THAN (1990)
     );

Suppose further that the minimum age for members is 16. As the calendar
approaches the end of 2005, you realize that you will soon be admitting
members who were born in 1990 (and later in years to come). You can
modify the `members' table to accommodate new members born in the years
1990-1999 as shown here:

     ALTER TABLE ADD PARTITION (PARTITION p3 VALUES LESS THAN (2000));

*Important*:

With tables that are partitioned by range, you can use `ADD PARTITION'
to add new partitions to the high end of the partitions list only.
Trying to add a new partition in this manner between or before existing
partitions will result in an error as shown here:

     mysql> ALTER TABLE members
          >     ADD PARTITION (
          >     PARTITION p3 VALUES LESS THAN (1960));
     ERROR 1463 (HY000): VALUES LESS THAN value must be strictly »
        increasing for each partition

In a similar fashion, you can add new partitions to a table that is
partitioned by `LIST'. For example, given a table defined like so:

     CREATE TABLE tt (
         id INT,
         data INT
     )
     PARTITION BY LIST(data) (
         PARTITION p0 VALUES IN (5, 10, 15),
         PARTITION p1 VALUES IN (6, 12, 18)
     );

You can add a new partition in which to store rows having the `data'
column values `7', `14', and `21' as shown:

     ALTER TABLE tt ADD PARTITION (PARTITION p2 VALUES IN (7, 14, 21));

Note that you _cannot_ add a new `LIST' partition encompassing any
values that are already included in the value list of an existing
partition.  If you attempt to do so, an error will result:

     mysql> ALTER TABLE tt ADD PARTITION
          >     (PARTITION np VALUES IN (4, 8, 12));
     ERROR 1465 (HY000): Multiple definition of same constant »
                         in list partitioning

Because any rows with the `data' column value `12' have already been
assigned to partition `p1', you cannot create a new partition on table
`tt' that includes `12' in its value list. To accomplish this, you
could drop `p1', and add `np' and then a new `p1' with a modified
definition. However, as discussed earlier, this would result in the
loss of all data stored in `p1' -- and it is often the case that this
is not what you really want to do. Another solution might appear to be
to make a copy of the table with the new partitioning and to copy the
data into it using `CREATE TABLE ... SELECT ...', then drop the old
table and rename the new one, but this could be very time-consuming when
dealing with a large amounts of data. This also might not be feasible
in situations where high availability is a requirement.

Beginning with MySQL 5.1.6, you can add multiple partitions in a single
`ALTER TABLE ... ADD PARTITION' statement as shown here:

     CREATE TABLE employees (
       id INT NOT NULL,
       fname VARCHAR(50) NOT NULL,
       lname VARCHAR(50) NOT NULL,
       hired DATE NOT NULL
     )
     PARTITION BY RANGE( YEAR(hired) ) (
       PARTITION p1 VALUES LESS THAN (1991),
       PARTITION p2 VALUES LESS THAN (1996),
       PARTITION p3 VALUES LESS THAN (2001),
       PARTITION p4 VALUES LESS THAN (2005)
     );

     ALTER TABLE employees ADD PARTITION (
         PARTITION p5 VALUES LESS THAN (2010),
         PARTITION p6 VALUES LESS THAN MAXVALUE
     );

Fortunately, MySQL's partitioning implementation provides ways to
redefine partitions without losing data. Let us look first at a couple
of simple examples involving `RANGE' partitioning. Recall the `members'
table which is now defined as shown here:

     mysql> SHOW CREATE TABLE members\G
     *************************** 1. row ***************************
            Table: members
     Create Table: CREATE TABLE `members` (
       `id` int(11) default NULL,
       `fname` varchar(25) default NULL,
       `lname` varchar(25) default NULL,
       `dob` date default NULL
     ) ENGINE=MyISAM DEFAULT CHARSET=latin1
     PARTITION BY RANGE ( YEAR(dob) ) (
       PARTITION p0 VALUES LESS THAN (1970) ENGINE = MyISAM,
       PARTITION p1 VALUES LESS THAN (1980) ENGINE = MyISAM,
       PARTITION p2 VALUES LESS THAN (1990) ENGINE = MyISAM.
       PARTITION p3 VALUES LESS THAN (2000) ENGINE = MyISAM
     )

Suppose that you would like to move all rows representing members born
before 1960 into a separate partition. As we have already seen, this
cannot be done using `ALTER TABLE ...  ADD PARTITION'. However, you can
use another partition-related extension to `ALTER TABLE' in order to
accomplish this:

     ALTER TABLE members REORGANIZE PARTITION p0 INTO (
         PARTITION s0 VALUES LESS THAN (1960),
         PARTITION s1 VALUES LESS THAN (1970)
     );

In effect, this command splits partition `p0' into two new partitions
`s0' and `s1'. It also moves the data that was stored in `p0' into the
new partitions according to the rules embodied in the two `PARTITION
... VALUES ...' clauses, so that `s0' contains only those records for
which `YEAR(dob)' is less than 1960 and `s1' contains those rows in
which `YEAR(dob)' is greater than or equal to 1960 but less than 1970.

A `REORGANIZE PARTITION' clause may also be used for merging adjacent
partitions. You can return the `members' table to its previous
partitioning as shown here:

     ALTER TABLE members REORGANIZE PARTITION s0,s1 INTO (
         PARTITION p0 VALUES LESS THAN (1970)
     );

No data is lost in splitting or merging partitions using `REORGANIZE
PARTITION'. In executing the above statement, MySQL moves all of the
records that were stored in partitions `s0' and `s1' into partition
`p0'.

The general syntax for `REORGANIZE PARTITION' is:

     ALTER TABLE TBL_NAME
         REORGANIZE PARTITION PARTITION_LIST
         INTO (PARTITION_DEFINITIONS);

Here, TBL_NAME is the name of the partitioned table, and PARTITION_LIST
is a comma-separated list of names of one or more existing partitions
to be changed.  PARTITION_DEFINITIONS is a comma-separated list of new
partition definitions, which follow the same rules as for the
PARTITION_DEFINITIONS list used in `CREATE TABLE' (see *Note
create-table::). It should be noted that you are not limited to merging
several partitions into one, or to splitting one partition into many,
when using `REORGANIZE PARTITION'. For example, you can reorganize all
four partitions of the `members' table into two, as follows:

     ALTER TABLE members REORGANIZE PARTITION p0,p1,p2,p3 INTO (
         PARTITION m0 VALUES LESS THAN (1980),
         PARTITION m1 VALUES LESS THAN (2000)
     );

You can also use `REORGANIZE PARTITION' with tables that are
partitioned by `LIST'. Let us return to the problem of adding a new
partition to the list-partitioned `tt' table and failing because the
new partition had a value that was already present in the value-list of
one of the existing partitions. We can handle this by adding a
partition that contains only non-conflicting values, and then
reorganizing the new partition and the existing one so that the value
which was stored in the existing one is now moved to the new one:

     ALTER TABLE tt ADD PARTITION (PARTITION np VALUES IN (4, 8));
     ALTER TABLE tt REORGANIZE PARTITION p1,np INTO (
         PARTITION p1 VALUES IN (6, 18),
         PARTITION np VALUES in (4, 8, 12)
     );

Here are some key points to keep in mind when using `ALTER TABLE ...
REORGANIZE PARTITION' to repartition tables that are partitioned by
`RANGE' or `LIST':

   * The `PARTITION' clauses used to determine the new partitioning
     scheme are subject to the same rules as those used with a `CREATE
     TABLE' statement.

     Most importantly, you should remember that the new partitioning
     scheme cannot have any overlapping ranges (applies to tables
     partitioned by `RANGE') or sets of values (when reorganizing
     tables partitioned by `LIST').

     *Note*:

     Prior to MySQL 5.1.4, you could not reuse the names of existing
     partitions in the `INTO' clause, even when those partitions were
     being dropped or redefined. See *Note news-5-1-4::, for more
     information.

   * The combination of partitions in the PARTITION_DEFINITIONS list
     should account for the same range or set of values overall as the
     combined partitions named in the PARTITION_LIST.

     For instance, in the `members' table used as an example in this
     section, partitions `p1' and `p2' together cover the years 1980
     through 1999. Therefore, any reorganization of these two
     partitions should cover the same range of years overall.

   * For tables partitioned by `RANGE', you can reorganize only
     adjacent partitions; you cannot skip over range partitions.

     For instance, you could not reorganize the `members' table used as
     an example in this section using a statement beginning with `ALTER
     TABLE members REORGANIZE PARTITION p0,p2 INTO ...' because `p0'
     covers the years prior to 1970 and `p2' the years from 1990
     through 1999 inclusive, and thus the two are not adjacent
     partitions.

   * You cannot use `REORGANIZE PARTITION' to change the table's
     partitioning type; that is, you cannot (for example) change
     `RANGE' partitions to `HASH' partitions or _vice versa_. You also
     cannot use this command to change the partitioning expression or
     column. To accomplish either of these tasks without dropping and
     re-creating the table, you can use `ALTER TABLE ... PARTITION BY
     ...'. For example:

          ALTER TABLE members
              PARTITION BY HASH( YEAR(dob) )
              PARTITIONS 8;


File: manual.info,  Node: partitioning-management-hash-key,  Next: partitioning-maintenance,  Prev: partitioning-management-range-list,  Up: partitioning-management

21.3.2 Management of `HASH' and `KEY' Partitions
------------------------------------------------

Tables which are partitioned by hash or by key are very similar to one
another with regard to making changes in a partitioning setup, and both
differ in a number of ways from tables which have been partitioned by
range or list. For that reason, this section addresses the modification
of tables partitioned by hash or by key only. For a discussion of
adding and dropping of partitions of tables that are partitioned by
range or list, see *Note partitioning-management-range-list::.

You cannot drop partitions from tables that are partitioned by `HASH'
or `KEY' in the same way that you can from tables that are partitioned
by `RANGE' or `LIST'. However, you can merge `HASH' or `KEY' partitions
using the `ALTER TABLE ... COALESCE PARTITION' command. For example,
suppose that you have a table containing data about clients, which is
divided into twelve partitions. The `clients' table is defined as shown
here:

     CREATE TABLE clients (
         id INT,
         fname VARCHAR(30),
         lname VARCHAR(30),
         signed DATE
     )
     PARTITION BY HASH( MONTH(signed) )
     PARTITIONS 12;

To reduce the number of partitions from twelve to eight, execute the
following `ALTER TABLE' command:

     mysql> ALTER TABLE clients COALESCE PARTITION 4;
     Query OK, 0 rows affected (0.02 sec)

`COALESCE' works equally well with tables that are partitioned by
`HASH', `KEY', `LINEAR HASH', or `LINEAR KEY'. Here is an example
similar to the previous one, differing only in that the table is
partitioned by `LINEAR KEY':

     mysql> CREATE TABLE clients_lk (
         ->     id INT,
         ->     fname VARCHAR(30),
         ->     lname VARCHAR(30),
         ->     signed DATE
         -> )
         -> PARTITION BY LINEAR KEY(signed)
         -> PARTITIONS 12;
     Query OK, 0 rows affected (0.03 sec)

     mysql> ALTER TABLE clients_lk COALESCE PARTITION 4;
     Query OK, 0 rows affected (0.06 sec)
     Records: 0  Duplicates: 0  Warnings: 0

Note that the number following `COALESCE PARTITION' is the number of
partitions to merge into the remainder -- in other words, it is the
number of partitions to remove from the table.

If you attempt to remove more partitions than the table has, the result
is an error like the one shown:

     mysql> ALTER TABLE clients COALESCE PARTITION 18;
     ERROR 1478 (HY000): Cannot remove all partitions, use DROP TABLE instead

To increase the number of partitions for the `clients' table from 12 to
18. use `ALTER TABLE ... ADD PARTITION' as shown here:

     ALTER TABLE clients ADD PARTITION PARTITIONS 6;


File: manual.info,  Node: partitioning-maintenance,  Next: partitioning-info,  Prev: partitioning-management-hash-key,  Up: partitioning-management

21.3.3 Maintenance of Partitions
--------------------------------

MySQL 5.1 does not support the statements `CHECK TABLE', `OPTIMIZE
TABLE', `ANALYZE TABLE', or `REPAIR TABLE' for partitioned tables.
However, there are alternatives available for performing partitioning
maintenance tasks.

Beginning with MySQL 5.1.5, you can rebuild partitions using `ALTER
TABLE ... REBUILD PARTITION', which has the same effect as dropping all
records stored in the partition, then reinserting them. This can be
useful for purposes of defragmentation. You can rebuild a one or more
partitions belonging to the same table at one time using this
statement, as shown in these examples:

     ALTER TABLE t1 REBUILD PARTITION p1;
     ALTER TABLE t1 REBUILD PARTITION p0, p2;

Executing the first statement rebuilds the partition named `p1' from
the table `t1'.  Performing the second statement rebuilds partitions
`p0' and `p2' from table `t1'.

`ALTER TABLE ... REORGANIZE PARTITION' also causes partition files to
be rebuilt.

*Note*:

The statements `ANALYZE PARTITION', `CHECK PARTITION', `OPTIMIZE
PARTITION', and `REPAIR PARTITION' -- intended to, respectively,
analyze, check, optimize, and repair individual or multiple partitions
-- were supported beginning with MySQL 5.1.5 and then removed in MySQL
5.1.24. (Bug#20129 (http://bugs.mysql.com/20129))

The use of `mysqlcheck' or `myisamchk' is also not supported with
partitioned tables.


File: manual.info,  Node: partitioning-info,  Prev: partitioning-maintenance,  Up: partitioning-management

21.3.4 Obtaining Information About Partitions
---------------------------------------------

This section discusses obtaining information about existing partitions,
which can be done in a number of ways. These include:

   * Using the `SHOW CREATE TABLE' statement to view the partitioning
     clauses used in creating a partitioned table.

   * Using the `SHOW TABLE STATUS' statement to determine whether a
     table is partitioned.

   * Querying the `INFORMATION_SCHEMA.PARTITIONS' table.

   * Using the statement `EXPLAIN PARTITIONS SELECT' to see which
     partitions are used by a given `SELECT'.

As discussed elsewhere in this chapter, `SHOW CREATE TABLE' includes in
its output the `PARTITION BY' clause used to create a partitioned
table. For example:

     mysql> SHOW CREATE TABLE trb3\G
     *************************** 1. row ***************************
            Table: trb3
     Create Table: CREATE TABLE `trb3` (
       `id` int(11) default NULL,
       `name` varchar(50) default NULL,
       `purchased` date default NULL
     ) ENGINE=MyISAM DEFAULT CHARSET=latin1
     PARTITION BY RANGE (YEAR(purchased)) (
       PARTITION p0 VALUES LESS THAN (1990) ENGINE = MyISAM,
       PARTITION p1 VALUES LESS THAN (1995) ENGINE = MyISAM,
       PARTITION p2 VALUES LESS THAN (2000) ENGINE = MyISAM,
       PARTITION p3 VALUES LESS THAN (2005) ENGINE = MyISAM
     )
     1 row in set (0.00 sec)

*Note*:

In early MySQL 5.1 releases, the `PARTITIONS' clause was not shown for
tables partitioned by `HASH' or `KEY'. This issue was fixed in MySQL
5.1.6.

`SHOW TABLE STATUS' works with partitioned tables. Beginning with MySQL
5.1.9, its output is the same as that for non-partitioned tables,
except that the `Create_options' column contains the string
`partitioned'. In MySQL 5.1.8 and earlier, the `Engine' column always
contained the value `PARTITION'; beginning with MySQL 5.1.9, this
column contains the name of the storage engine used by all partitions
of the table. (See *Note show-table-status::, for more information about
this statement.)

You can also obtain information about partitions from
`INFORMATION_SCHEMA', which contains a `PARTITIONS' table. See *Note
partitions-table::.

Beginning with MySQL 5.1.5, it is possible to determine which
partitions of a partitioned table are involved in a given `SELECT'
query using `EXPLAIN PARTITIONS'. The `PARTITIONS' keyword adds a
`partitions' column to the output of `EXPLAIN' listing the partitions
from which records would be matched by the query.

Suppose that you have a table `trb1' defined and populated as follows:

     CREATE TABLE trb1 (id INT, name VARCHAR(50), purchased DATE)
         PARTITION BY RANGE(id)
         (
             PARTITION p0 VALUES LESS THAN (3),
             PARTITION p1 VALUES LESS THAN (7),
             PARTITION p2 VALUES LESS THAN (9),
             PARTITION p3 VALUES LESS THAN (11)
         );

     INSERT INTO trb1 VALUES
         (1, 'desk organiser', '2003-10-15'),
         (2, 'CD player', '1993-11-05'),
         (3, 'TV set', '1996-03-10'),
         (4, 'bookcase', '1982-01-10'),
         (5, 'exercise bike', '2004-05-09'),
         (6, 'sofa', '1987-06-05'),
         (7, 'popcorn maker', '2001-11-22'),
         (8, 'aquarium', '1992-08-04'),
         (9, 'study desk', '1984-09-16'),
         (10, 'lava lamp', '1998-12-25');

You can see which partitions are used in a query such as `SELECT * FROM
trb1;', as shown here:

     mysql> EXPLAIN PARTITIONS SELECT * FROM trb1\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: trb1
        partitions: p0,p1,p2,p3
              type: ALL
     possible_keys: NULL
               key: NULL
           key_len: NULL
               ref: NULL
              rows: 10
             Extra: Using filesort

In this case, all four partitions are searched. However, when a
limiting condition making use of the partitioning key is added to the
query, you can see that only those partitions containing matching
values are scanned, as shown here:

     mysql> EXPLAIN PARTITIONS SELECT * FROM trb1 WHERE id < 5\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: trb1
        partitions: p0,p1
              type: ALL
     possible_keys: NULL
               key: NULL
           key_len: NULL
               ref: NULL
              rows: 10
             Extra: Using where

`EXPLAIN PARTITIONS' provides information about keys used and possible
keys, just as with the standard `EXPLAIN SELECT' statement:

     mysql> ALTER TABLE trb1 ADD PRIMARY KEY (id);
     Query OK, 10 rows affected (0.03 sec)
     Records: 10  Duplicates: 0  Warnings: 0

     mysql> EXPLAIN PARTITIONS SELECT * FROM trb1 WHERE id < 5\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: trb1
        partitions: p0,p1
              type: range
     possible_keys: PRIMARY
               key: PRIMARY
           key_len: 4
               ref: NULL
              rows: 7
             Extra: Using where

You should take note of the following restrictions and limitations on
`EXPLAIN PARTITIONS':

   * You cannot use the `PARTITIONS' and `EXTENDED' keywords together
     in the same `EXPLAIN ... SELECT' statement. Attempting to do so
     produces a syntax error.

   * If `EXPLAIN PARTITIONS' is used to examine a query against a
     non-partitioned table, no error is produced, but the value of the
     `partitions' column is always `NULL'.

As of MySQL 5.1.28, the `rows' column of `EXPLAIN PARTITIONS' output
always displays the total number of records in the table. Previously,
this was the number of matching rows. (Bug#35745
(http://bugs.mysql.com/35745))

See also *Note explain::.


File: manual.info,  Node: partitioning-pruning,  Next: partitioning-limitations,  Prev: partitioning-management,  Up: partitioning

21.4 Partition Pruning
======================

This section discusses an optimization known as _partition pruning_,
which was implemented for partitioned tables in MySQL 5.1.6. The core
concept behind partition pruning is relatively simple, and can be
described as `Do not scan partitions where there can be no matching
values'. For example, suppose you have a partitioned table `t1' defined
by this statement:

     CREATE TABLE t1 (
         fname VARCHAR(50) NOT NULL,
         lname VARCHAR(50) NOT NULL,
         region_code TINYINT UNSIGNED NOT NULL,
         dob DATE NOT NULL
     )
     PARTITION BY RANGE( region_code ) (
         PARTITION p0 VALUES LESS THAN (64),
         PARTITION p1 VALUES LESS THAN (128),
         PARTITION p2 VALUES LESS THAN (192)
         PARTITION p3 VALUES LESS THAN MAXVALUE
     );

Consider the case where you wish to obtain results from a query such as
this one:

     SELECT fname, lname, postcode, dob
         FROM t1
         WHERE region_code > 125 AND region_code < 130;

It is easy to see that none of the rows which ought to be returned will
be in either of the partitions `p0' or `p3'; that is, we need to search
only in partitions `p1' and `p2' to find matching rows. By doing so, it
is possible to expend much more time and effort in finding matching
rows than it is to scan all partitions in the table. This `cutting
away' of unneeded partitions is known as _pruning_.  When the optimizer
can make use of partition pruning in performing a query, execution of
the query can be an order of magnitude faster than the same query
against a non-partitioned table containing the same column definitions
and data.

The query optimizer can perform pruning whenever a `WHERE' condition
can be reduced to either one of the following:

   * `PARTITION_COLUMN = CONSTANT'

   * `PARTITION_COLUMN IN (CONSTANT1, CONSTANT2, ..., CONSTANTN)'

In the first case, the optimizer simply evaluates the partitioning
expression for the value given, determines which partition contains
that value, and scans only this partition. In many cases, the equals
sign can be replaced with another arithmetic comparison, including `<',
`>', `<=', `>=', and `<>'. Some queries using `BETWEEN' in the `WHERE'
clause can also take advantage of partition pruning. See the examples
later in this section.

In the second case, the optimizer evaluates the partitioning expression
for each value in the list, creates a list of matching partitions, and
then scans only the partitions in this partition list.

Pruning can also be applied to short ranges, which the optimizer can
convert into equivalent lists of values. For instance, in the previous
example, the `WHERE' clause can be converted to `WHERE region_code IN
(125, 126, 127, 128, 129, 130)'. Then the optimizer can determine that
the first three values in the list are found in partition `p1', the
remaining three values in partition `p2', and that the other partitions
contain no relevant values and so do not need to be searched for
matching rows.

This type of optimization can be applied whenever the partitioning
expression consists of an equality or a range which can be reduced to a
set of equalities, or when the partitioning expression represents an
increasing or decreasing relationship. Pruning can also be applied for
tables partitioned on a `DATE' or `DATETIME' column when the
partitioning expression uses the `YEAR()' or `TO_DAYS()' function.

*Note*:

We plan to add pruning support in a future MySQL release for additional
functions that act on a `DATE' or `DATETIME' value, return an integer,
and are increasing or decreasing.

For example, suppose that table `t2', defined as shown here, is
partitioned on a `DATE' column:

     CREATE TABLE t2 (
         fname VARCHAR(50) NOT NULL,
         lname VARCHAR(50) NOT NULL,
         region_code TINYINT UNSIGNED NOT NULL,
         dob DATE NOT NULL
     )
     PARTITION BY RANGE( YEAR(dob) ) (
         PARTITION d0 VALUES LESS THAN (1970),
         PARTITION d1 VALUES LESS THAN (1975),
         PARTITION d2 VALUES LESS THAN (1980),
         PARTITION d3 VALUES LESS THAN (1985),
         PARTITION d4 VALUES LESS THAN (1990),
         PARTITION d5 VALUES LESS THAN (2000),
         PARTITION d6 VALUES LESS THAN (2005),
         PARTITION d7 VALUES LESS THAN MAXVALUE
     );

The following queries on `t2' can make of use partition pruning:

     SELECT * FROM t2 WHERE dob = '1982-06-23';

     SELECT * FROM t2 WHERE dob BETWEEN '1991-02-15' AND '1997-04-25';

     SELECT * FROM t2 WHERE YEAR(dob)
              IN (1979, 1980, 1983, 1985, 1986, 1988);

     SELECT * FROM t2 WHERE dob >= '1984-06-21' AND dob <= '1999-06-21'

In the case of the last query, the optimizer can also act as follows:

  1. _Find the partition containing the low end of the range_.

     `YEAR('1984-06-21')' yields the value `1984', which is found in
     partition `d3'.

  2. _Find the partition containing the high end of the range_.

     `YEAR('1999-06-21')' evaluates to `1999', which is found in
     partition `d5'.

  3. _Scan only these two partitions and any partitions that may lie
     between them_.

     In this case, this means that only partitions `d3', `d4', and `d5'
     are scanned. The remaining partitions may be safely ignored (and
     are ignored).

So far, we have looked only at examples using `RANGE' partitioning, but
pruning can be applied with other partitioning types as well.

Consider a table that is partitioned by `LIST', where the partitioning
expression is increasing or decreasing, such as the table `t3' shown
here. (In this example, we assume for the sake of brevity that the
`region_code' column is limited to values between 1 and 10 inclusive.)

     CREATE TABLE t3 (
         fname VARCHAR(50) NOT NULL,
         lname VARCHAR(50) NOT NULL,
         region_code TINYINT UNSIGNED NOT NULL,
         dob DATE NOT NULL
     )
     PARTITION BY LIST(region_code) (
         PARTITION r0 VALUES IN (1, 3),
         PARTITION r1 VALUES IN (2, 5, 8),
         PARTITION r2 VALUES IN (4, 9),
         PARTITION r3 VALUES IN (6, 7, 10)
     );

For a query such as `SELECT * FROM t3 WHERE region_code BETWEEN 1 AND
3', the optimizer determines in which partitions the values 1, 2, and 3
are found (`r0' and `r1') and skips the remaining ones (`r2' and `r3').

For tables that are partitioned by `HASH' or `KEY', partition pruning
is also possible in cases in which the `WHERE' clause uses a simple `='
relation against a column used in the partitioning expression. Consider
a table created like this:

     CREATE TABLE t4 (
         fname VARCHAR(50) NOT NULL,
         lname VARCHAR(50) NOT NULL,
         region_code TINYINT UNSIGNED NOT NULL,
         dob DATE NOT NULL
     )
     PARTITION BY KEY(region_code)
     PARTITIONS 8;

Any query such as this one can be pruned:

     SELECT * FROM t4 WHERE region_code = 7;

Pruning can also be employed for short ranges, because the optimizer
can turn such conditions into `IN' relations. For example, using the
same table `t4' as defined previously, queries such as these can be
pruned:

     SELECT * FROM t4 WHERE region_code > 2 AND region_code < 6;

     SELECT * FROM t4 WHERE region_code BETWEEN 3 AND 5;

In both these cases, the `WHERE' clause is transformed by the optimizer
into `WHERE region_code IN (3, 4, 5)'.

*Important*:

This optimization is used only if the range size is smaller than the
number of partitions. Consider this query:

     SELECT * FROM t4 WHERE region_code BETWEEN 4 AND 8;

The range in the `WHERE' clause covers 5 values (4, 5, 6, 7, 8), but
`t4' has only 4 partitions. This means that the previous query cannot
be pruned.

Pruning can be used only on integer columns of tables partitioned by
`HASH' or `KEY'. For example, this query on table `t4' cannot use
pruning because `dob' is a `DATE' column:

     SELECT * FROM t4 WHERE dob >=- '2001-04-14' AND dob <= '2005-10-15';

However, if the table stores year values in an `INT' column, then a
query having `WHERE year_col >= 2001 AND year_col <= 2005' can be
pruned.


File: manual.info,  Node: partitioning-limitations,  Prev: partitioning-pruning,  Up: partitioning

21.5 Restrictions and Limitations on Partitioning
=================================================

* Menu:

* partitioning-limitations-partitioning-keys-unique-keys::  Partitioning Keys, Primary Keys, and Unique Keys
* partitioning-limitations-storage-engines::  Partitioning Limitations Relating to Storage Engines
* partitioning-limitations-functions::  Partitioning Limitations Relating to Functions

This section discusses current restrictions and limitations on MySQL
partitioning support, as listed here:

   * Prohibited constructs

     Beginning with MySQL 5.1.12, the following constructs are not
     permitted in partitioning expressions:

        * Stored functions, stored procedures, UDFs, or plugins.

        * Nested function calls. For example, while `MOD()' and
          `TO_DAYS()' are both permitted in partitioning expressions,
          an expression such as `MOD(TO_DAYS(DATETIME_COLUMN), 7)' is
          not allowed.

        * Declared variables or user variables.

     For a list of SQL functions which are permitted in partitioning
     expressions, see *Note partitioning-limitations-functions::.

   * Arithmetic and logical operators

     Use of the arithmetic operators `+', `-', and `*' is permitted in
     partitioning expressions. However, the result must be an integer
     value or `NULL' (except in the case of `[LINEAR] KEY' partitioning,
     as discussed elswhere in this chapter -- see *Note
     partitioning-types::, for more information).

     Beginning with MySQL 5.1.23, the `DIV' operator is also supported,
     and the `/' operator is disallowed. (Bug#30188
     (http://bugs.mysql.com/30188), Bug#33182
     (http://bugs.mysql.com/33182))

     Beginning with MySQL 5.1.12, the bit operators `|', `&', `^', `<<',
     `>>', and `~' are not permitted in partitioning expressions.

   * Server SQL mode

     Tables employing user-defined partitioning do not preserve the SQL
     mode in effect at the time that they were created.  As discussed
     in *Note server-sql-mode::, the results of many MySQL functions
     and operators may change according to the server SQL mode.
     Therefore, a change in the SQL mode at any time after the creation
     of partitioned tables may lead to major changes in the behavior of
     such tables, and could easily lead to corruption or loss of data.
     For these reasons, _it is strongly recommended that you never
     change the server SQL mode after creating partitioned tables_.

     Examples

     The following examples illustrate some changes in behavior of
     partitioned tables due to a change in the server SQL mode:

       1. Error handling

          Suppose you create a partitioned table whose partitioning
          expression is one such as `COLUMN DIV 0' or `COLUMN MOD 0',
          as shown here:

               mysql> CREATE TABLE tn (c1 INT)
                   ->     PARTITION BY LIST(1 DIV c1) (
                   ->       PARTITION p0 VALUES IN (NULL),
                   ->       PARTITION p1 VALUES IN (1)
                   -> );
               Query OK, 0 rows affected (0.05 sec)

          The default behavior for MySQL is to return `NULL' for the
          result of a division by zero, without producing any errors:

               mysql> SELECT @@SQL_MODE;
               +------------+
               | @@SQL_MODE |
               +------------+
               |            |
               +------------+
               1 row in set (0.00 sec)

               mysql> INSERT INTO tn VALUES (NULL), (0), (1);
               Query OK, 3 rows affected (0.00 sec)
               Records: 3  Duplicates: 0  Warnings: 0

          However, changing the server SQL mode to treat division by
          zero as an error and to enforce strict error handling causes
          the same `INSERT' statement to fail, as shown here:

               mysql> SET SQL_MODE='STRICT_ALL_TABLES,ERROR_FOR_DIVISION_BY_ZERO';
               Query OK, 0 rows affected (0.00 sec)

               mysql> INSERT INTO tn VALUES (NULL), (0), (1);
               `ERROR 1365 (22012): Division by 0'

       2. Table accessibility

          Sometimes a change in the server SQL mode can make
          partitioned tables unusable. The following `CREATE TABLE'
          statement can be executed successfully only if the
          `NO_UNSIGNED_SUBTRACTION' mode is in effect:

               mysql> SELECT @@SQL_MODE;
               +------------+
               | @@SQL_MODE |
               +------------+
               |            |
               +------------+
               1 row in set (0.00 sec)

               mysql> CREATE TABLE tu (c1 BIGINT UNSIGNED)
                   ->   PARTITION BY RANGE(c1 - 10) (
                   ->     PARTITION p0 VALUES LESS THAN (-5),
                   ->     PARTITION p1 VALUES LESS THAN (0),
                   ->     PARTITION p2 VALUES LESS THAN (5),
                   ->     PARTITION p3 VALUES LESS THAN (10),
                   ->     PARTITION p4 VALUES LESS THAN (MAXVALUE)
                   -> );
               `ERROR 1563 (HY000): Partition constant is out of partition function domain'

               mysql> SET SQL_MODE='NO_UNSIGNED_SUBTRACTION';
               Query OK, 0 rows affected (0.00 sec)

               mysql> SELECT @@SQL_MODE;
               +-------------------------+
               | @@SQL_MODE              |
               +-------------------------+
               | NO_UNSIGNED_SUBTRACTION |
               +-------------------------+
               1 row in set (0.00 sec)

               mysql> CREATE TABLE tu (c1 BIGINT UNSIGNED)
                   ->   PARTITION BY RANGE(c1 - 10) (
                   ->     PARTITION p0 VALUES LESS THAN (-5),
                   ->     PARTITION p1 VALUES LESS THAN (0),
                   ->     PARTITION p2 VALUES LESS THAN (5),
                   ->     PARTITION p3 VALUES LESS THAN (10),
                   ->     PARTITION p4 VALUES LESS THAN (MAXVALUE)
                   -> );
               Query OK, 0 rows affected (0.05 sec)

          If you remove the `NO_UNSIGNED_SUBTRACTION' server SQL mode
          after creating `tu', you may no longer be able to access this
          table:

               mysql> SET SQL_MODE='';
               Query OK, 0 rows affected (0.00 sec)

               mysql> SELECT * FROM tu;
               `ERROR 1563 (HY000): Partition constant is out of partition function domain'
               mysql> INSERT INTO tu VALUES (20);
               `ERROR 1563 (HY000): Partition constant is out of partition function domain'

   * Performance considerations

        * Filesystem operations

          Partitioning and repartitioning operations (such as `ALTER
          TABLE' with `PARTITION BY ...', `REORGANIZE PARTITIONS', or
          `REMOVE PARTITIONING') depend on filesystem operations for
          their implementation. This means that the speed of these
          operations is affected by such factors as filesystem type and
          characteristics, disk speed, swap space, file handling
          efficiency of the operating system, and MySQL server options
          and variables that relate to file handling. In particular,
          you should make sure that `large_files_support' is enabled
          and that `open_files_limit' is set properly. For partitioned
          tables using the `MyISAM' storage engine, increasing
          `myisam_max_sort_file_size' may improve performance;
          partitioning and repartitioning operations involving `InnoDB'
          tables may be made more efficient by enabling
          `innodb_file_per_table'.

        * Table locks

          The process executing a partitioning operation on a table
          takes a write lock on the table. Reads from such tables are
          relatively unaffected; pending `INSERT' and `UPDATE'
          operations are performed as soon as the partitioning
          operation has completed.

        * Storage engine

          Partitioning operations, queries, and update operations
          generally tend to be faster with `MyISAM' tables than with
          `InnoDB' or `NDB' tables.

        * Use of indexes and partition pruning

          As with non-partitioned tables, proper use of indexes can
          speed up queries on partitioned tables significantly. In
          addition, designing partitioned tables and queries on these
          tables to take advantage of _partition pruning_ can improve
          performance dramatically. See *Note partitioning-pruning::,
          for more information.

        * Performance with `LOAD DATA'

          Prior to MySQL 5.1.23, `LOAD DATA' performed very poorly when
          importing into partitioned tables. The statement now uses
          buffering to improve performance; however, the buffer uses 130
          KB memory per partition to achieve this. (Bug#26527
          (http://bugs.mysql.com/26527))

   * Maximum number of partitions

     The maximum number of partitions possible for a given table is
     1024. This includes subpartitions.

     If, when creating tables with a very large number of partitions
     (but which is less than the maximum stated previously), you
     encounter an error message such as `Got error 24 from storage
     engine', this means that you may need to increase the value of the
     `open_files_limit' system variable. See *Note
     not-enough-file-handles::.

   * Foreign keys not supported

     Partitioned tables do not support foreign keys. This means that:

       1. Definitions of tables employing user-defined partitioning may
          not contain foreign key references to other tables.

       2. No table definition may contain a foreign key reference to a
          partitioned table.

     The scope of these restrictions includes tables that use the
     `InnoDB' storage engine.

   * `ALTER TABLE ... ORDER BY'

     An `ALTER TABLE ... ORDER BY COLUMN' statement run against a
     partitioned table causes ordering of rows only within each
     partition.

   * FULLTEXT indexes

     Partitioned tables do not support `FULLTEXT' indexes. This includes
     partitioned tables employing the `MyISAM' storage engine.

   * Spatial columns

     Columns with spatial data types such as `POINT' or `GEOMETRY'
     cannot be used in partitioned tables.

   * Temporary tables

     As of MySQL 5.1.8, temporary tables cannot be partitioned.
     (Bug#17497 (http://bugs.mysql.com/17497))

   * Log tables

     Beginning with MySQL 5.1.20, it is no longer possible to partition
     the log tables; beginning with that version, an `ALTER TABLE ...
     PARTITION BY ...' statement on such a table fails with an error.
     (Bug#27816 (http://bugs.mysql.com/27816))

   * Data type of partitioning key

     A partitioning key must be either an integer column or an
     expression that resolves to an integer. The column or expression
     value may also be `NULL'. (See *Note
     partitioning-handling-nulls::.)

     The lone exception to this restriction occurs when partitioning by
     [`LINEAR'] `KEY', where it is possible to use columns of other
     types as partitioning keys, because MySQL's internal key-hashing
     functions produce the correct data type from these types. For
     example, the following `CREATE TABLE' statement is valid:

          CREATE TABLE tkc (c1 CHAR)
          PARTITION BY KEY(c1)
          PARTITIONS 4;

     This exception does _not_ apply to `BLOB' or `TEXT' column types.

   * Subqueries

     A partitioning key may not be a subquery, even if that subquery
     resolves to an integer value or `NULL'.

   * Subpartitions

     Subpartitions are limited to `HASH' or `KEY' partitioning. `HASH'
     and `KEY' partitions cannot be subpartitioned.

   * Key caches not supported

     Key caches are not supported for partitioned tables. The `LOAD
     CACHE' and `LOAD INDEX INTO CACHE' statements, when you attempt to
     use them on tables having user-defined partitioning, fail with the
     errors `The storage engine for the table doesn't support
     assign_to_keycache' and `The storage engine for the table doesn't
     support preload_keys', respectively.

   * `DELAYED' option not supported

     Use of `INSERT DELAYED' to insert rows into a partitioned table is
     not supported. Beginning with MySQL 5.1.23, attempting to do so
     fails with an error. (Bug#31210 (http://bugs.mysql.com/31210))

   * `DATA DIRECTORY' and `INDEX DIRECTORY' options

     `DATA DIRECTORY' and `INDEX DIRECTORY' are subject to the following
     restrictions when used with partitioned tables:

        * Beginning with MySQL 5.1.23, table-level `DATA DIRECTORY' and
          `INDEX DIRECTORY' are ignored. (Bug#32091
          (http://bugs.mysql.com/32091))

        * On Windows, the `DATA DIRECTORY' and `INDEX DIRECTORY'
          options are not supported for individual partitions or
          subpartitions (Bug#30459 (http://bugs.mysql.com/30459)).

   * Repairing and rebuilding partitioned tables

     The statements `CHECK TABLE', `OPTIMIZE TABLE', `ANALYZE TABLE',
     and `REPAIR TABLE' are not supported for partitioned tables.
     `mysqlcheck' and `myisamchk' are also not supported for
     partitioned tables. However, you can use `ALTER TABLE ... REBUILD
     PARTITION' to rebuild one or more partitions of a partitioned
     table; `ALTER TABLE ...  REORGANIZE PARTITION' also causes
     partitions to be rebuilt. See *Note alter-table::, for more
     information about these two statements.


File: manual.info,  Node: partitioning-limitations-partitioning-keys-unique-keys,  Next: partitioning-limitations-storage-engines,  Prev: partitioning-limitations,  Up: partitioning-limitations

21.5.1 Partitioning Keys, Primary Keys, and Unique Keys
-------------------------------------------------------

This section discusses the relationship of partitioning keys with
primary keys and unique keys. The rule governing this relationship can
be expressed as follows: All columns used in the partitioning
expression for a partitioned table must be part of every unique key
that the table may have.

In other words, _every unique key on the table must use every column in
the table's partitioning expression_.  (This also includes the table's
primary key, since it is by definition a unique key. This particular
case is discussed later in this section.) For example, each of the
following table creation statements is invalid:

     CREATE TABLE t1 (
         col1 INT NOT NULL,
         col2 DATE NOT NULL,
         col3 INT NOT NULL,
         col4 INT NOT NULL,
         UNIQUE KEY (col1, col2)
     )
     PARTITION BY HASH(col3)
     PARTITIONS 4;

     CREATE TABLE t2 (
         col1 INT NOT NULL,
         col2 DATE NOT NULL,
         col3 INT NOT NULL,
         col4 INT NOT NULL,
         UNIQUE KEY (col1),
         UNIQUE KEY (col3)
     )
     PARTITION BY HASH(col1 + col3)
     PARTITIONS 4;

In each case, the proposed table would have at least one unique key
that does not include all columns used in the partitioning expression.

Each of the following statements is valid, and represents one way in
which the corresponding invalid table creation statement could be made
to work:

     CREATE TABLE t1 (
         col1 INT NOT NULL,
         col2 DATE NOT NULL,
         col3 INT NOT NULL,
         col4 INT NOT NULL,
         UNIQUE KEY (col1, col2, col3)
     )
     PARTITION BY HASH(col3)
     PARTITIONS 4;

     CREATE TABLE t2 (
         col1 INT NOT NULL,
         col2 DATE NOT NULL,
         col3 INT NOT NULL,
         col4 INT NOT NULL,
         UNIQUE KEY (col1, col3)
     )
     PARTITION BY HASH(col1 + col3)
     PARTITIONS 4;

This example shows the error produced in such cases:

     mysql> CREATE TABLE t3 (
         ->     col1 INT NOT NULL,
         ->     col2 DATE NOT NULL,
         ->     col3 INT NOT NULL,
         ->     col4 INT NOT NULL,
         ->     UNIQUE KEY (col1, col2),
         ->     UNIQUE KEY (col3)
         -> )
         -> PARTITION BY HASH(col1 + col3)
         -> PARTITIONS 4;
     `ERROR 1491 (HY000): A PRIMARY KEY must include all columns in the table's partitioning function'

The `CREATE' statement fails because both `col1' and `col3' are included
in the proposed partitioning key, but neither of these columns is part
of both of unique keys on the table. This shows one possible fix for
the invalid table definition;

     mysql> CREATE TABLE t3 (
         ->     col1 INT NOT NULL,
         ->     col2 DATE NOT NULL,
         ->     col3 INT NOT NULL,
         ->     col4 INT NOT NULL,
         ->     UNIQUE KEY (col1, col2, col3),
         ->     UNIQUE KEY (col3)
         -> )
         -> PARTITION BY HASH(col3)
         -> PARTITIONS 4;
     Query OK, 0 rows affected (0.05 sec)

In this case, the proposed partitioning key `col3' is part of both
unique keys, and the table creation statement succeeds.

Since every primary key is by definition a unique key, this restriction
also includes the table's primary key, if it has one. For example, the
next two statements are invalid:

     CREATE TABLE t4 (
         col1 INT NOT NULL,
         col2 DATE NOT NULL,
         col3 INT NOT NULL,
         col4 INT NOT NULL,
         PRIMARY KEY(col1, col2)
     )
     PARTITION BY HASH(col3)
     PARTITIONS 4;

     CREATE TABLE t5 (
         col1 INT NOT NULL,
         col2 DATE NOT NULL,
         col3 INT NOT NULL,
         col4 INT NOT NULL,
         PRIMARY KEY(col1, col3),
         UNIQUE KEY(col2)
     )
     PARTITION BY HASH( YEAR(col2) )
     PARTITIONS 4;

In both cases, the primary key does not include all columns referenced
in the partitioning expression. However, both of the next two
statements are valid:

     CREATE TABLE t6 (
         col1 INT NOT NULL,
         col2 DATE NOT NULL,
         col3 INT NOT NULL,
         col4 INT NOT NULL,
         PRIMARY KEY(col1, col2)
     )
     PARTITION BY HASH(col1 + YEAR(col2))
     PARTITIONS 4;

     CREATE TABLE t7 (
         col1 INT NOT NULL,
         col2 DATE NOT NULL,
         col3 INT NOT NULL,
         col4 INT NOT NULL,
         PRIMARY KEY(col1, col2, col4),
         UNIQUE KEY(col2, col1)
     )
     PARTITION BY HASH(col1 + YEAR(col2))
     PARTITIONS 4;

If a table has no unique keys -- this includes having no primary key --
then this restriction does not apply, and you may use any column or
columns in the partitioning expression as long as the column type is
compatible with the partitioning type.

For the same reason, you cannot later add a unique key to a partitioned
table unless the key includes all columns used by the table's
partitioning expression. Consider given the partitioned table defined
as shown here:

     mysql> CREATE TABLE t_no_pk (c1 INT, c2 INT)
         ->     PARTITION BY RANGE(c1) (
         ->         PARTITION p0 VALUES LESS THAN (10),
         ->         PARTITION p1 VALUES LESS THAN (20),
         ->         PARTITION p2 VALUES LESS THAN (30),
         ->         PARTITION p3 VALUES LESS THAN (40)
         ->     );
     Query OK, 0 rows affected (0.12 sec)

It is possible to add a primary key to `t_no_pk' using either of these
`ALTER TABLE' statements:

     #  possible PK
     mysql> ALTER TABLE t_no_pk ADD PRIMARY KEY(c1);
     Query OK, 0 rows affected (0.13 sec)
     Records: 0  Duplicates: 0  Warnings: 0

     # drop this PK
     mysql> ALTER TABLE t_no_pk DROP PRIMARY KEY;
     Query OK, 0 rows affected (0.10 sec)
     Records: 0  Duplicates: 0  Warnings: 0

     #  use another possible PK
     mysql> ALTER TABLE t_no_pk ADD PRIMARY KEY(c1, c2);
     Query OK, 0 rows affected (0.12 sec)
     Records: 0  Duplicates: 0  Warnings: 0

     # drop this PK
     mysql> ALTER TABLE t_no_pk DROP PRIMARY KEY;
     Query OK, 0 rows affected (0.09 sec)
     Records: 0  Duplicates: 0  Warnings: 0

However, the next statement fails, because `c1' is part of the
partitioning key, but is not part of the proposed primary key:

     #  fails with error 1503
     mysql> ALTER TABLE t_no_pk ADD PRIMARY KEY(c2);
     `ERROR 1503 (HY000): A PRIMARY KEY must include all columns in the table's partitioning function'

Since `t_no_pk' has only `c1' in its partitioning expression,
attempting to adding a unique key on `c2' alone fails. However, you can
add a unique key that uses both `c1' and `c2'.

These rules also apply to existing non-partitioned tables that you wish
to partition using `ALTER TABLE ... PARTITION BY'. Consider a table
`np_pk' defined as shown here:

     mysql> CREATE TABLE np_pk (
         ->     id INT NOT NULL AUTO_INCREMENT,
         ->     name VARCHAR(50),
         ->     added DATE,
         ->     PRIMARY KEY (id)
         -> );
     Query OK, 0 rows affected (0.08 sec)

The following `ALTER TABLE' statements fails with an error, because the
`added' column is not part of any unique key in the table:

     mysql> ALTER TABLE np_pk
         ->     PARTITION BY HASH( TO_DAYS(added) )
         ->     PARTITIONS 4;
     `ERROR 1503 (HY000): A PRIMARY KEY must include all columns in the table's partitioning function'

However, this statement using the `id' column for the partitioning
column is valid, as shown here:

     mysql> ALTER TABLE np_pk
         ->     PARTITION BY HASH(id)
         ->     PARTITIONS 4;
     Query OK, 0 rows affected (0.11 sec)
     Records: 0  Duplicates: 0  Warnings: 0

In the case of `np_pk', the only column that may be used as part of a
partitioning expression is `id'; if you wish to partition this table
using any other column or columns in the partitioning expression, you
must first modify the table, either by adding the desired column or
columns to the primary key, or by dropping the primary key altogether.

We are working to remove this limitation in a future MySQL release
series.


File: manual.info,  Node: partitioning-limitations-storage-engines,  Next: partitioning-limitations-functions,  Prev: partitioning-limitations-partitioning-keys-unique-keys,  Up: partitioning-limitations

21.5.2 Partitioning Limitations Relating to Storage Engines
-----------------------------------------------------------

The following limitations apply to the use of storage engines with
user-defined partitioning of tables.

`MERGE' storage engine

User-defined partitioning and the `MERGE' storage engine are not
compatible. Tables using the `MERGE' storage engine cannot be
partitioned.  Partitioned tables cannot be merged.

`FEDERATED' storage engine

Partitioning of `FEDERATED' tables is not supported. Beginning with
MySQL 5.1.15, it is not possible to create partitioned `FEDERATED'
tables at all.  We are working to remove this limitation in a future
MySQL release.

`CSV' storage engine

Partitioned tables using the `CSV' storage engine are not supported.
Starting with MySQL 5.1.12, it is not possible to create partitioned
`CSV' tables at all.

`BLACKHOLE' storage engine

Prior to MySQL 5.1.6, tables using the `BLACKHOLE' storage engine also
could not be partitioned.

`NDB' storage engine (MySQL Cluster)

Partitioning by `KEY' (or `LINEAR KEY') is the only type of
partitioning supported for the `NDBCLUSTER' storage engine. Beginning
with MySQL 5.1.12, it is not possible to create a MySQL Cluster table
using any partitioning type other than [`LINEAR'] `KEY', and attempting
to do so fails with an error.

Upgrading partitioned tables

When performing an upgrade, tables which are partitioned by `KEY' and
which use any storage engine other than `NDBCLUSTER' must be dumped and
reloaded.

Same storage engine for all partitions

All partitions of a partitioned table must use the same storage engine
and it must be the same storage engine used by the table as a whole. In
addition, if one does not specify an engine on the table level, then
one must do either of the following when creating or altering a
partitioned table:

   * Do _not_ specify any engine for _any_ partition or subpartition

   * Specify the engine for _all_ partitions or subpartitions

We are working to remove this limitation in a future MySQL release.


File: manual.info,  Node: partitioning-limitations-functions,  Prev: partitioning-limitations-storage-engines,  Up: partitioning-limitations

21.5.3 Partitioning Limitations Relating to Functions
-----------------------------------------------------

This section discusses limitations in MySQL Partitioning relating
specifically to functions used in partitioning expressions.

Beginning with MySQL 5.1.12, only the following MySQL functions are
supported in partitioning expressions:

   * `ABS()'

   * `CEILING()' (see ``CEILING()' and `FLOOR()'', immediately
     following this list)

   * `DAY()'

   * `DAYOFMONTH()'

   * `DAYOFWEEK()'

   * `DAYOFYEAR()'

   * `DATEDIFF()'

   * `EXTRACT()'

   * `FLOOR()' (see ``CEILING()' and `FLOOR()'', immediately following
     this list)

   * `HOUR()'

   * `MICROSECOND()'

   * `MINUTE()'

   * `MOD()'

   * `MONTH()'

   * `QUARTER()'

   * `SECOND()'

   * `TIME_TO_SEC()'

   * `TO_DAYS()'

   * `WEEKDAY()'

   * `YEAR()'

   * `YEARWEEK()'

*Note*:

`CEILING()' and `FLOOR()'

Each of these functions returns an integer only if it is passed an
integer argument. This means, for example, that the following `CREATE
TABLE' statement fails with an error, as shown here:

     mysql> CREATE TABLE t (c FLOAT) PARTITION BY LIST( FLOOR(c) )(
         ->     PARTITION p0 VALUES IN (1,3,5),
         ->     PARTITION p1 VALUES IN (2,4,6)
         -> );
     `ERROR 1490 (HY000): The PARTITION function returns the wrong type'

See *Note mathematical-functions::, for more information about the
return types of these functions.


File: manual.info,  Node: spatial-extensions,  Next: stored-procedures,  Prev: partitioning,  Up: Top

22 Spatial Extensions
*********************

* Menu:

* gis-introduction::             Introduction to MySQL Spatial Support
* opengis-geometry-model::       The OpenGIS Geometry Model
* supported-spatial-data-formats::  Supported Spatial Data Formats
* creating-a-spatially-enabled-mysql-database::  Creating a Spatially Enabled MySQL Database
* analysing-spatial-information::  Analyzing Spatial Information
* optimizing-spatial-analysis::  Optimizing Spatial Analysis
* mysql-gis-conformance-and-compatibility::  MySQL Conformance and Compatibility

MySQL supports spatial extensions to allow the generation, storage, and
analysis of geographic features. These features are available for
`MyISAM', `InnoDB', `NDB', and `ARCHIVE' tables.

For spatial columns, `MyISAM' supports both `SPATIAL' and non-`SPATIAL'
indexes. Other storage engines support non-`SPATIAL' indexes, as
described in *Note create-index::.

This chapter covers the following topics:

   * The basis of these spatial extensions in the OpenGIS geometry model

   * Data formats for representing spatial data

   * How to use spatial data in MySQL

   * Use of indexing for spatial data

   * MySQL differences from the OpenGIS specification

*Additional resources*

   * The Open Geospatial Consortium publishes the `OpenGIS(R) Simple
     Features Specifications For SQL', a document that proposes several
     conceptual ways for extending an SQL RDBMS to support spatial
     data. This specification is available from the OGC Web site at
     `http://www.opengis.org/docs/99-049.pdf'.

   * If you have questions or concerns about the use of the spatial
     extensions to MySQL, you can discuss them in the GIS forum:
     `http://forums.mysql.com/list.php?23'.


File: manual.info,  Node: gis-introduction,  Next: opengis-geometry-model,  Prev: spatial-extensions,  Up: spatial-extensions

22.1 Introduction to MySQL Spatial Support
==========================================

MySQL implements spatial extensions following the specification of the
Open Geospatial Consortium (OGC). This is an international consortium
of more than 250 companies, agencies, and universities participating in
the development of publicly available conceptual solutions that can be
useful with all kinds of applications that manage spatial data. The OGC
maintains a Web site at `http://www.opengis.org/'.

In 1997, the Open Geospatial Consortium published the `OpenGIS(R)
Simple Features Specifications For SQL', a document that proposes
several conceptual ways for extending an SQL RDBMS to support spatial
data. This specification is available from the OGC Web site at
`http://www.opengis.org/docs/99-049.pdf'. It contains additional
information relevant to this chapter.

MySQL implements a subset of the *SQL with Geometry Types* environment
proposed by OGC. This term refers to an SQL environment that has been
extended with a set of geometry types. A geometry-valued SQL column is
implemented as a column that has a geometry type. The specification
describe a set of SQL geometry types, as well as functions on those
types to create and analyze geometry values.

A *geographic feature* is anything in the world that has a location. A
feature can be:

   * An entity. For example, a mountain, a pond, a city.

   * A space. For example, town district, the tropics.

   * A definable location. For example, a crossroad, as a particular
     place where two streets intersect.

Some documents use the term *geospatial feature* to refer to geographic
features.

*Geometry* is another word that denotes a geographic feature.
Originally the word *geometry* meant measurement of the earth. Another
meaning comes from cartography, referring to the geometric features
that cartographers use to map the world.

This chapter uses all of these terms synonymously: *geographic feature*,
*geospatial feature*, *feature*, or *geometry*. Here, the term most
commonly used is *geometry*, defined as _a point or an aggregate of
points representing anything in the world that has a location_.


File: manual.info,  Node: opengis-geometry-model,  Next: supported-spatial-data-formats,  Prev: gis-introduction,  Up: spatial-extensions

22.2 The OpenGIS Geometry Model
===============================

* Menu:

* gis-geometry-class-hierarchy::  The Geometry Class Hierarchy
* gis-class-geometry::           Class `Geometry'
* gis-class-point::              Class `Point'
* gis-class-curve::              Class `Curve'
* gis-class-linestring::         Class `LineString'
* gis-class-surface::            Class `Surface'
* gis-class-polygon::            Class `Polygon'
* gis-class-geometrycollection::  Class `GeometryCollection'
* gis-class-multipoint::         Class `MultiPoint'
* gis-class-multicurve::         Class `MultiCurve'
* gis-class-multilinestring::    Class `MultiLineString'
* gis-class-multisurface::       Class `MultiSurface'
* gis-class-multipolygon::       Class `MultiPolygon'

The set of geometry types proposed by OGC's *SQL with Geometry Types*
environment is based on the *OpenGIS Geometry Model*. In this model,
each geometric object has the following general properties:

   * It is associated with a Spatial Reference System, which describes
     the coordinate space in which the object is defined.

   * It belongs to some geometry class.


File: manual.info,  Node: gis-geometry-class-hierarchy,  Next: gis-class-geometry,  Prev: opengis-geometry-model,  Up: opengis-geometry-model

22.2.1 The Geometry Class Hierarchy
-----------------------------------

The geometry classes define a hierarchy as follows:

   * `Geometry' (non-instantiable)

        * `Point' (instantiable)

        * `Curve' (non-instantiable)

             * `LineString' (instantiable)

                  * `Line'

                  * `LinearRing'

        * `Surface' (non-instantiable)

             * `Polygon' (instantiable)

        * `GeometryCollection' (instantiable)

             * `MultiPoint' (instantiable)

             * `MultiCurve' (non-instantiable)

                  * `MultiLineString' (instantiable)

             * `MultiSurface' (non-instantiable)

                  * `MultiPolygon' (instantiable)

It is not possible to create objects in non-instantiable classes. It is
possible to create objects in instantiable classes. All classes have
properties, and instantiable classes may also have assertions (rules
that define valid class instances).

`Geometry' is the base class. It is an abstract class. The instantiable
subclasses of `Geometry' are restricted to zero-, one-, and
two-dimensional geometric objects that exist in two-dimensional
coordinate space. All instantiable geometry classes are defined so that
valid instances of a geometry class are topologically closed (that is,
all defined geometries include their boundary).

The base `Geometry' class has subclasses for `Point', `Curve',
`Surface', and `GeometryCollection':

   * `Point' represents zero-dimensional objects.

   * `Curve' represents one-dimensional objects, and has subclass
     `LineString', with sub-subclasses `Line' and `LinearRing'.

   * `Surface' is designed for two-dimensional objects and has subclass
     `Polygon'.

   * `GeometryCollection' has specialized zero-, one-, and
     two-dimensional collection classes named `MultiPoint',
     `MultiLineString', and `MultiPolygon' for modeling geometries
     corresponding to collections of `Points', `LineStrings', and
     `Polygons', respectively.  `MultiCurve' and `MultiSurface' are
     introduced as abstract superclasses that generalize the collection
     interfaces to handle `Curves' and `Surfaces'.

`Geometry', `Curve', `Surface', `MultiCurve', and `MultiSurface' are
defined as non-instantiable classes. They define a common set of
methods for their subclasses and are included for extensibility.

`Point', `LineString', `Polygon', `GeometryCollection', `MultiPoint',
`MultiLineString', and `MultiPolygon' are instantiable classes.


File: manual.info,  Node: gis-class-geometry,  Next: gis-class-point,  Prev: gis-geometry-class-hierarchy,  Up: opengis-geometry-model

22.2.2 Class `Geometry'
-----------------------

`Geometry' is the root class of the hierarchy.  It is a
non-instantiable class but has a number of properties that are common
to all geometry values created from any of the `Geometry' subclasses.
These properties are described in the following list. Particular
subclasses have their own specific properties, described later.

*Geometry Properties*

A geometry value has the following properties:

   * Its *type*. Each geometry belongs to one of the instantiable
     classes in the hierarchy.

   * Its *SRID*, or Spatial Reference Identifier. This value identifies
     the geometry's associated Spatial Reference System that describes
     the coordinate space in which the geometry object is defined.

     In MySQL, the SRID value is just an integer associated with the
     geometry value. All calculations are done assuming Euclidean
     (planar) geometry.

   * Its *coordinates* in its Spatial Reference System, represented as
     double-precision (eight-byte) numbers. All non-empty geometries
     include at least one pair of (X,Y) coordinates. Empty geometries
     contain no coordinates.

     Coordinates are related to the SRID. For example, in different
     coordinate systems, the distance between two objects may differ
     even when objects have the same coordinates, because the distance
     on the *planar* coordinate system and the distance on the
     *geocentric* system (coordinates on the Earth's surface) are
     different things.

   * Its *interior*, *boundary*, and *exterior*.

     Every geometry occupies some position in space. The exterior of a
     geometry is all space not occupied by the geometry. The interior
     is the space occupied by the geometry. The boundary is the
     interface between the geometry's interior and exterior.

   * Its *MBR* (Minimum Bounding Rectangle), or Envelope. This is the
     bounding geometry, formed by the minimum and maximum (X,Y)
     coordinates:

          ((MINX MINY, MAXX MINY, MAXX MAXY, MINX MAXY, MINX MINY))

   * Whether the value is *simple* or *non-simple*. Geometry values of
     types (`LineString', `MultiPoint', `MultiLineString') are either
     simple or non-simple. Each type determines its own assertions for
     being simple or non-simple.

   * Whether the value is *closed* or *not closed*. Geometry values of
     types (`LineString', `MultiString') are either closed or not
     closed. Each type determines its own assertions for being closed
     or not closed.

   * Whether the value is *empty* or *non-empty* A geometry is empty if
     it does not have any points. Exterior, interior, and boundary of
     an empty geometry are not defined (that is, they are represented
     by a `NULL' value). An empty geometry is defined to be always
     simple and has an area of 0.

   * Its *dimension*. A geometry can have a dimension of -1, 0, 1, or 2:

        * -1 for an empty geometry.

        * 0 for a geometry with no length and no area.

        * 1 for a geometry with non-zero length and zero area.

        * 2 for a geometry with non-zero area.

     `Point' objects have a dimension of zero.  `LineString' objects
     have a dimension of 1.  `Polygon' objects have a dimension of 2.
     The dimensions of `MultiPoint', `MultiLineString', and
     `MultiPolygon' objects are the same as the dimensions of the
     elements they consist of.


File: manual.info,  Node: gis-class-point,  Next: gis-class-curve,  Prev: gis-class-geometry,  Up: opengis-geometry-model

22.2.3 Class `Point'
--------------------

A `Point' is a geometry that represents a single location in coordinate
space.

*`Point' Examples*

   * Imagine a large-scale map of the world with many cities. A `Point'
     object could represent each city.

   * On a city map, a `Point' object could represent a bus stop.

*`Point' Properties*

   * X-coordinate value.

   * Y-coordinate value.

   * `Point' is defined as a zero-dimensional geometry.

   * The boundary of a `Point' is the empty set.


File: manual.info,  Node: gis-class-curve,  Next: gis-class-linestring,  Prev: gis-class-point,  Up: opengis-geometry-model

22.2.4 Class `Curve'
--------------------

A `Curve' is a one-dimensional geometry, usually represented by a
sequence of points. Particular subclasses of `Curve' define the type of
interpolation between points. `Curve' is a non-instantiable class.

*`Curve' Properties*

   * A `Curve' has the coordinates of its points.

   * A `Curve' is defined as a one-dimensional geometry.

   * A `Curve' is simple if it does not pass through the same point
     twice.

   * A `Curve' is closed if its start point is equal to its endpoint.

   * The boundary of a closed `Curve' is empty.

   * The boundary of a non-closed `Curve' consists of its two endpoints.

   * A `Curve' that is simple and closed is a `LinearRing'.


File: manual.info,  Node: gis-class-linestring,  Next: gis-class-surface,  Prev: gis-class-curve,  Up: opengis-geometry-model

22.2.5 Class `LineString'
-------------------------

A `LineString' is a `Curve' with linear interpolation between points.

*`LineString' Examples*

   * On a world map, `LineString' objects could represent rivers.

   * In a city map, `LineString' objects could represent streets.

*`LineString' Properties*

   * A `LineString' has coordinates of segments, defined by each
     consecutive pair of points.

   * A `LineString' is a `Line' if it consists of exactly two points.

   * A `LineString' is a `LinearRing' if it is both closed and simple.


File: manual.info,  Node: gis-class-surface,  Next: gis-class-polygon,  Prev: gis-class-linestring,  Up: opengis-geometry-model

22.2.6 Class `Surface'
----------------------

A `Surface' is a two-dimensional geometry. It is a non-instantiable
class. Its only instantiable subclass is `Polygon'.

*`Surface' Properties*

   * A `Surface' is defined as a two-dimensional geometry.

   * The OpenGIS specification defines a simple `Surface' as a geometry
     that consists of a single `patch' that is associated with a single
     exterior boundary and zero or more interior boundaries.

   * The boundary of a simple `Surface' is the set of closed curves
     corresponding to its exterior and interior boundaries.


File: manual.info,  Node: gis-class-polygon,  Next: gis-class-geometrycollection,  Prev: gis-class-surface,  Up: opengis-geometry-model

22.2.7 Class `Polygon'
----------------------

A `Polygon' is a planar `Surface' representing a multisided geometry.
It is defined by a single exterior boundary and zero or more interior
boundaries, where each interior boundary defines a hole in the
`Polygon'.

*`Polygon' Examples*

   * On a region map, `Polygon' objects could represent forests,
     districts, and so on.

*`Polygon' Assertions*

   * The boundary of a `Polygon' consists of a set of `LinearRing'
     objects (that is, `LineString' objects that are both simple and
     closed) that make up its exterior and interior boundaries.

   * A `Polygon' has no rings that cross. The rings in the boundary of
     a `Polygon' may intersect at a `Point', but only as a tangent.

   * A `Polygon' has no lines, spikes, or punctures.

   * A `Polygon' has an interior that is a connected point set.

   * A `Polygon' may have holes. The exterior of a `Polygon' with holes
     is not connected.  Each hole defines a connected component of the
     exterior.

The preceding assertions make a `Polygon' a simple geometry.


File: manual.info,  Node: gis-class-geometrycollection,  Next: gis-class-multipoint,  Prev: gis-class-polygon,  Up: opengis-geometry-model

22.2.8 Class `GeometryCollection'
---------------------------------

A `GeometryCollection' is a geometry that is a collection of one or
more geometries of any class.

All the elements in a `GeometryCollection' must be in the same Spatial
Reference System (that is, in the same coordinate system). There are no
other constraints on the elements of a `GeometryCollection', although
the subclasses of `GeometryCollection' described in the following
sections may restrict membership.  Restrictions may be based on:

   * Element type (for example, a `MultiPoint' may contain only `Point'
     elements)

   * Dimension

   * Constraints on the degree of spatial overlap between elements


File: manual.info,  Node: gis-class-multipoint,  Next: gis-class-multicurve,  Prev: gis-class-geometrycollection,  Up: opengis-geometry-model

22.2.9 Class `MultiPoint'
-------------------------

A `MultiPoint' is a geometry collection composed of `Point' elements.
The points are not connected or ordered in any way.

*`MultiPoint' Examples*

   * On a world map, a `MultiPoint' could represent a chain of small
     islands.

   * On a city map, a `MultiPoint' could represent the outlets for a
     ticket office.

*`MultiPoint' Properties*

   * A `MultiPoint' is a zero-dimensional geometry.

   * A `MultiPoint' is simple if no two of its `Point' values are equal
     (have identical coordinate values).

   * The boundary of a `MultiPoint' is the empty set.


File: manual.info,  Node: gis-class-multicurve,  Next: gis-class-multilinestring,  Prev: gis-class-multipoint,  Up: opengis-geometry-model

22.2.10 Class `MultiCurve'
--------------------------

A `MultiCurve' is a geometry collection composed of `Curve' elements.
`MultiCurve' is a non-instantiable class.

*`MultiCurve' Properties*

   * A `MultiCurve' is a one-dimensional geometry.

   * A `MultiCurve' is simple if and only if all of its elements are
     simple; the only intersections between any two elements occur at
     points that are on the boundaries of both elements.

   * A `MultiCurve' boundary is obtained by applying the `mod 2 union
     rule' (also known as the `odd-even rule'): A point is in the
     boundary of a `MultiCurve' if it is in the boundaries of an odd
     number of `MultiCurve' elements.

   * A `MultiCurve' is closed if all of its elements are closed.

   * The boundary of a closed `MultiCurve' is always empty.


File: manual.info,  Node: gis-class-multilinestring,  Next: gis-class-multisurface,  Prev: gis-class-multicurve,  Up: opengis-geometry-model

22.2.11 Class `MultiLineString'
-------------------------------

A `MultiLineString' is a `MultiCurve' geometry collection composed of
`LineString' elements.

*`MultiLineString' Examples*

   * On a region map, a `MultiLineString' could represent a river
     system or a highway system.


File: manual.info,  Node: gis-class-multisurface,  Next: gis-class-multipolygon,  Prev: gis-class-multilinestring,  Up: opengis-geometry-model

22.2.12 Class `MultiSurface'
----------------------------

A `MultiSurface' is a geometry collection composed of surface elements.
`MultiSurface' is a non-instantiable class. Its only instantiable
subclass is `MultiPolygon'.

*`MultiSurface' Assertions*

   * Two `MultiSurface' surfaces have no interiors that intersect.

   * Two `MultiSurface' elements have boundaries that intersect at most
     at a finite number of points.


File: manual.info,  Node: gis-class-multipolygon,  Prev: gis-class-multisurface,  Up: opengis-geometry-model

22.2.13 Class `MultiPolygon'
----------------------------

A `MultiPolygon' is a `MultiSurface' object composed of `Polygon'
elements.

*`MultiPolygon' Examples*

   * On a region map, a `MultiPolygon' could represent a system of
     lakes.

*`MultiPolygon' Assertions*

   * A `MultiPolygon' has no two `Polygon' elements with interiors that
     intersect.

   * A `MultiPolygon' has no two `Polygon' elements that cross
     (crossing is also forbidden by the previous assertion), or that
     touch at an infinite number of points.

   * A `MultiPolygon' may not have cut lines, spikes, or punctures. A
     `MultiPolygon' is a regular, closed point set.

   * A `MultiPolygon' that has more than one `Polygon' has an interior
     that is not connected. The number of connected components of the
     interior of a `MultiPolygon' is equal to the number of `Polygon'
     values in the `MultiPolygon'.

*`MultiPolygon' Properties*

   * A `MultiPolygon' is a two-dimensional geometry.

   * A `MultiPolygon' boundary is a set of closed curves (`LineString'
     values) corresponding to the boundaries of its `Polygon' elements.

   * Each `Curve' in the boundary of the `MultiPolygon' is in the
     boundary of exactly one `Polygon' element.

   * Every `Curve' in the boundary of an `Polygon' element is in the
     boundary of the `MultiPolygon'.


File: manual.info,  Node: supported-spatial-data-formats,  Next: creating-a-spatially-enabled-mysql-database,  Prev: opengis-geometry-model,  Up: spatial-extensions

22.3 Supported Spatial Data Formats
===================================

* Menu:

* gis-wkt-format::               Well-Known Text (WKT) Format
* gis-wkb-format::               Well-Known Binary (WKB) Format

This section describes the standard spatial data formats that are used
to represent geometry objects in queries. They are:

   * Well-Known Text (WKT) format

   * Well-Known Binary (WKB) format

Internally, MySQL stores geometry values in a format that is not
identical to either WKT or WKB format.


File: manual.info,  Node: gis-wkt-format,  Next: gis-wkb-format,  Prev: supported-spatial-data-formats,  Up: supported-spatial-data-formats

22.3.1 Well-Known Text (WKT) Format
-----------------------------------

The Well-Known Text (WKT) representation of Geometry is designed to
exchange geometry data in ASCII form.

Examples of WKT representations of geometry objects:

   * A `Point':

          POINT(15 20)

     Note that point coordinates are specified with no separating comma.

   * A `LineString' with four points:

          LINESTRING(0 0, 10 10, 20 25, 50 60)

     Note that point coordinate pairs are separated by commas.

   * A `Polygon' with one exterior ring and one interior ring:

          POLYGON((0 0,10 0,10 10,0 10,0 0),(5 5,7 5,7 7,5 7, 5 5))

   * A `MultiPoint' with three `Point' values:

          MULTIPOINT(0 0, 20 20, 60 60)

   * A `MultiLineString' with two `LineString' values:

          MULTILINESTRING((10 10, 20 20), (15 15, 30 15))

   * A `MultiPolygon' with two `Polygon' values:

          MULTIPOLYGON(((0 0,10 0,10 10,0 10,0 0)),((5 5,7 5,7 7,5 7, 5 5)))

   * A `GeometryCollection' consisting of two `Point' values and one
     `LineString':

          GEOMETRYCOLLECTION(POINT(10 10), POINT(30 30), LINESTRING(15 15, 20 20))

A Backus-Naur grammar that specifies the formal production rules for
writing WKT values can be found in the OpenGIS specification document
referenced near the beginning of this chapter.


File: manual.info,  Node: gis-wkb-format,  Prev: gis-wkt-format,  Up: supported-spatial-data-formats

22.3.2 Well-Known Binary (WKB) Format
-------------------------------------

The Well-Known Binary (WKB) representation for geometric values is
defined by the OpenGIS specification. It is also defined in the ISO
`SQL/MM Part 3: Spatial' standard.

WKB is used to exchange geometry data as binary streams represented by
`BLOB' values containing geometric WKB information.

WKB uses one-byte unsigned integers, four-byte unsigned integers, and
eight-byte double-precision numbers (IEEE 754 format). A byte is eight
bits.

For example, a WKB value that corresponds to `POINT(1 1)' consists of
this sequence of 21 bytes (each represented here by two hex digits):

     0101000000000000000000F03F000000000000F03F

The sequence may be broken down into these components:

     Byte order : 01
     WKB type   : 01000000
     X          : 000000000000F03F
     Y          : 000000000000F03F

Component representation is as follows:

   * The byte order may be either 1 or 0 to indicate little-endian or
     big-endian storage. The little-endian and big-endian byte orders
     are also known as Network Data Representation (NDR) and External
     Data Representation (XDR), respectively.

   * The WKB type is a code that indicates the geometry type.  Values
     from 1 through 7 indicate `Point', `LineString', `Polygon',
     `MultiPoint', `MultiLineString', `MultiPolygon', and
     `GeometryCollection'.

   * A `Point' value has X and Y coordinates, each represented as a
     double-precision value.

WKB values for more complex geometry values are represented by more
complex data structures, as detailed in the OpenGIS specification.


File: manual.info,  Node: creating-a-spatially-enabled-mysql-database,  Next: analysing-spatial-information,  Prev: supported-spatial-data-formats,  Up: spatial-extensions

22.4 Creating a Spatially Enabled MySQL Database
================================================

* Menu:

* mysql-spatial-datatypes::      MySQL Spatial Data Types
* creating-spatial-values::      Creating Spatial Values
* creating-spatial-columns::     Creating Spatial Columns
* populating-spatial-columns::   Populating Spatial Columns
* fetching-spatial-data::        Fetching Spatial Data

This section describes the data types you can use for representing
spatial data in MySQL, and the functions available for creating and
retrieving spatial values.


File: manual.info,  Node: mysql-spatial-datatypes,  Next: creating-spatial-values,  Prev: creating-a-spatially-enabled-mysql-database,  Up: creating-a-spatially-enabled-mysql-database

22.4.1 MySQL Spatial Data Types
-------------------------------

MySQL has data types that correspond to OpenGIS classes. Some of these
types hold single geometry values:

   * `GEOMETRY'

   * `POINT'

   * `LINESTRING'

   * `POLYGON'

`GEOMETRY' can store geometry values of any type. The other
single-value types (`POINT', `LINESTRING', and `POLYGON') restrict
their values to a particular geometry type.

The other data types hold collections of values:

   * `MULTIPOINT'

   * `MULTILINESTRING'

   * `MULTIPOLYGON'

   * `GEOMETRYCOLLECTION'

`GEOMETRYCOLLECTION' can store a collection of objects of any type. The
other collection types (`MULTIPOINT', `MULTILINESTRING',
`MULTIPOLYGON', and `GEOMETRYCOLLECTION') restrict collection members
to those having a particular geometry type.


File: manual.info,  Node: creating-spatial-values,  Next: creating-spatial-columns,  Prev: mysql-spatial-datatypes,  Up: creating-a-spatially-enabled-mysql-database

22.4.2 Creating Spatial Values
------------------------------

* Menu:

* gis-wkt-functions::            Creating Geometry Values Using WKT Functions
* gis-wkb-functions::            Creating Geometry Values Using WKB Functions
* gis-mysql-specific-functions::  Creating Geometry Values Using MySQL-Specific Functions

This section describes how to create spatial values using Well-Known
Text and Well-Known Binary functions that are defined in the OpenGIS
standard, and using MySQL-specific functions.


File: manual.info,  Node: gis-wkt-functions,  Next: gis-wkb-functions,  Prev: creating-spatial-values,  Up: creating-spatial-values

22.4.2.1 Creating Geometry Values Using WKT Functions
.....................................................

MySQL provides a number of functions that take as input parameters a
Well-Known Text representation and, optionally, a spatial reference
system identifier (SRID). They return the corresponding geometry.

`GeomFromText()' accepts a WKT of any geometry type as its first
argument. An implementation also provides type-specific construction
functions for construction of geometry values of each geometry type.

   *  `GeomCollFromText(WKT[,SRID])',
     `GeometryCollectionFromText(WKT[,SRID])'

     Constructs a `GEOMETRYCOLLECTION' value using its WKT
     representation and SRID.

   *  `GeomFromText(WKT[,SRID])', `GeometryFromText(WKT[,SRID])'

     Constructs a geometry value of any type using its WKT
     representation and SRID.

   *  `LineFromText(WKT[,SRID])', `LineStringFromText(WKT[,SRID])'

     Constructs a `LINESTRING' value using its WKT representation and
     SRID.

   *  `MLineFromText(WKT[,SRID])', `MultiLineStringFromText(WKT[,SRID])'

     Constructs a `MULTILINESTRING' value using its WKT representation
     and SRID.

   *  `MPointFromText(WKT[,SRID])', `MultiPointFromText(WKT[,SRID])'

     Constructs a `MULTIPOINT' value using its WKT representation and
     SRID.

   *  `MPolyFromText(WKT[,SRID])', `MultiPolygonFromText(WKT[,SRID])'

     Constructs a `MULTIPOLYGON' value using its WKT representation and
     SRID.

   *  `PointFromText(WKT[,SRID])'

     Constructs a `POINT' value using its WKT representation and SRID.

   *  `PolyFromText(WKT[,SRID])', `PolygonFromText(WKT[,SRID])'

     Constructs a `POLYGON' value using its WKT representation and SRID.

The OpenGIS specification also defines the following optional
functions, which MySQL does not implement. These functions construct
`Polygon' or `MultiPolygon' values based on the WKT representation of a
collection of rings or closed `LineString' values. These values may
intersect.

   *  `BdMPolyFromText(WKT,SRID)'

     Constructs a `MultiPolygon' value from a `MultiLineString' value
     in WKT format containing an arbitrary collection of closed
     `LineString' values.

   *  `BdPolyFromText(WKT,SRID)'

     Constructs a `Polygon' value from a `MultiLineString' value in WKT
     format containing an arbitrary collection of closed `LineString'
     values.


File: manual.info,  Node: gis-wkb-functions,  Next: gis-mysql-specific-functions,  Prev: gis-wkt-functions,  Up: creating-spatial-values

22.4.2.2 Creating Geometry Values Using WKB Functions
.....................................................

MySQL provides a number of functions that take as input parameters a
`BLOB' containing a Well-Known Binary representation and, optionally, a
spatial reference system identifier (SRID). They return the
corresponding geometry.

`GeomFromWKB()' accepts a WKB of any geometry type as its first
argument. An implementation also provides type-specific construction
functions for construction of geometry values of each geometry type.

   *  `GeomCollFromWKB(WKB[,SRID])',
     `GeometryCollectionFromWKB(WKB[,SRID])'

     Constructs a `GEOMETRYCOLLECTION' value using its WKB
     representation and SRID.

   *  `GeomFromWKB(WKB[,SRID])', `GeometryFromWKB(WKB[,SRID])'

     Constructs a geometry value of any type using its WKB
     representation and SRID.

   *  `LineFromWKB(WKB[,SRID])', `LineStringFromWKB(WKB[,SRID])'

     Constructs a `LINESTRING' value using its WKB representation and
     SRID.

   *  `MLineFromWKB(WKB[,SRID])', `MultiLineStringFromWKB(WKB[,SRID])'

     Constructs a `MULTILINESTRING' value using its WKB representation
     and SRID.

   *  `MPointFromWKB(WKB[,SRID])', `MultiPointFromWKB(WKB[,SRID])'

     Constructs a `MULTIPOINT' value using its WKB representation and
     SRID.

   *  `MPolyFromWKB(WKB[,SRID])', `MultiPolygonFromWKB(WKB[,SRID])'

     Constructs a `MULTIPOLYGON' value using its WKB representation and
     SRID.

   *  `PointFromWKB(WKB[,SRID])'

     Constructs a `POINT' value using its WKB representation and SRID.

   *  `PolyFromWKB(WKB[,SRID])', `PolygonFromWKB(WKB[,SRID])'

     Constructs a `POLYGON' value using its WKB representation and SRID.

The OpenGIS specification also describes optional functions for
constructing `Polygon' or `MultiPolygon' values based on the WKB
representation of a collection of rings or closed `LineString' values.
These values may intersect. MySQL does not implement these functions:

   *  `BdMPolyFromWKB(WKB,SRID)'

     Constructs a `MultiPolygon' value from a `MultiLineString' value
     in WKB format containing an arbitrary collection of closed
     `LineString' values.

   *  `BdPolyFromWKB(WKB,SRID)'

     Constructs a `Polygon' value from a `MultiLineString' value in WKB
     format containing an arbitrary collection of closed `LineString'
     values.


File: manual.info,  Node: gis-mysql-specific-functions,  Prev: gis-wkb-functions,  Up: creating-spatial-values

22.4.2.3 Creating Geometry Values Using MySQL-Specific Functions
................................................................

MySQL provides a set of useful non-standard functions for creating
geometry WKB representations. The functions described in this section
are MySQL extensions to the OpenGIS specification. The results of these
functions are `BLOB' values containing WKB representations of geometry
values with no SRID. The results of these functions can be substituted
as the first argument for any function in the `GeomFromWKB()' function
family.

   *  `GeometryCollection(G1,G2,...)'

     Constructs a WKB `GeometryCollection'. If any argument is not a
     well-formed WKB representation of a geometry, the return value is
     `NULL'.

   *  `LineString(PT1,PT2,...)'

     Constructs a WKB `LineString' value from a number of WKB `Point'
     arguments. If any argument is not a WKB `Point', the return value
     is `NULL'. If the number of `Point' arguments is less than two, the
     return value is `NULL'.

   *  `MultiLineString(LS1,LS2,...)'

     Constructs a WKB `MultiLineString' value using WKB `LineString'
     arguments. If any argument is not a WKB `LineString', the return
     value is `NULL'.

   *  `MultiPoint(PT1,PT2,...)'

     Constructs a WKB `MultiPoint' value using WKB `Point' arguments.
     If any argument is not a WKB `Point', the return value is `NULL'.

   *  `MultiPolygon(POLY1,POLY2,...)'

     Constructs a WKB `MultiPolygon' value from a set of WKB `Polygon'
     arguments. If any argument is not a WKB `Polygon', the return
     value is `NULL'.

   *  `Point(X,Y)'

     Constructs a WKB `Point' using its coordinates.

   *  `Polygon(LS1,LS2,...)'

     Constructs a WKB `Polygon' value from a number of WKB `LineString'
     arguments. If any argument does not represent the WKB of a
     `LinearRing' (that is, not a closed and simple `LineString') the
     return value is `NULL'.


File: manual.info,  Node: creating-spatial-columns,  Next: populating-spatial-columns,  Prev: creating-spatial-values,  Up: creating-a-spatially-enabled-mysql-database

22.4.3 Creating Spatial Columns
-------------------------------

MySQL provides a standard way of creating spatial columns for geometry
types, for example, with `CREATE TABLE' or `ALTER TABLE'. Currently,
spatial columns are supported for `MyISAM', `InnoDB', `NDB', and
`ARCHIVE' tables. See also the annotations about spatial indexes under
*Note creating-spatial-indexes::.

   * Use the `CREATE TABLE' statement to create a table with a spatial
     column:

          CREATE TABLE geom (g GEOMETRY);

   * Use the `ALTER TABLE' statement to add or drop a spatial column to
     or from an existing table:

          ALTER TABLE geom ADD pt POINT;
          ALTER TABLE geom DROP pt;


File: manual.info,  Node: populating-spatial-columns,  Next: fetching-spatial-data,  Prev: creating-spatial-columns,  Up: creating-a-spatially-enabled-mysql-database

22.4.4 Populating Spatial Columns
---------------------------------

After you have created spatial columns, you can populate them with
spatial data.

Values should be stored in internal geometry format, but you can
convert them to that format from either Well-Known Text (WKT) or
Well-Known Binary (WKB) format. The following examples demonstrate how
to insert geometry values into a table by converting WKT values into
internal geometry format:

   * Perform the conversion directly in the `INSERT' statement:

          INSERT INTO geom VALUES (GeomFromText('POINT(1 1)'));

          SET @g = 'POINT(1 1)';
          INSERT INTO geom VALUES (GeomFromText(@g));

   * Perform the conversion prior to the `INSERT':

          SET @g = GeomFromText('POINT(1 1)');
          INSERT INTO geom VALUES (@g);

The following examples insert more complex geometries into the table:

     SET @g = 'LINESTRING(0 0,1 1,2 2)';
     INSERT INTO geom VALUES (GeomFromText(@g));

     SET @g = 'POLYGON((0 0,10 0,10 10,0 10,0 0),(5 5,7 5,7 7,5 7, 5 5))';
     INSERT INTO geom VALUES (GeomFromText(@g));

     SET @g =
     'GEOMETRYCOLLECTION(POINT(1 1),LINESTRING(0 0,1 1,2 2,3 3,4 4))';
     INSERT INTO geom VALUES (GeomFromText(@g));

The preceding examples all use `GeomFromText()' to create geometry
values. You can also use type-specific functions:

     SET @g = 'POINT(1 1)';
     INSERT INTO geom VALUES (PointFromText(@g));

     SET @g = 'LINESTRING(0 0,1 1,2 2)';
     INSERT INTO geom VALUES (LineStringFromText(@g));

     SET @g = 'POLYGON((0 0,10 0,10 10,0 10,0 0),(5 5,7 5,7 7,5 7, 5 5))';
     INSERT INTO geom VALUES (PolygonFromText(@g));

     SET @g =
     'GEOMETRYCOLLECTION(POINT(1 1),LINESTRING(0 0,1 1,2 2,3 3,4 4))';
     INSERT INTO geom VALUES (GeomCollFromText(@g));

Note that if a client application program wants to use WKB
representations of geometry values, it is responsible for sending
correctly formed WKB in queries to the server. However, there are
several ways of satisfying this requirement. For example:

   * Inserting a `POINT(1 1)' value with hex literal syntax:

          mysql> INSERT INTO geom VALUES
              -> (GeomFromWKB(0x0101000000000000000000F03F000000000000F03F));

   * An ODBC application can send a WKB representation, binding it to a
     placeholder using an argument of `BLOB' type:

          INSERT INTO geom VALUES (GeomFromWKB(?))

     Other programming interfaces may support a similar placeholder
     mechanism.

   * In a C program, you can escape a binary value using *Note
     `mysql_real_escape_string()': mysql-real-escape-string.  and
     include the result in a query string that is sent to the server.
     See *Note mysql-real-escape-string::.


File: manual.info,  Node: fetching-spatial-data,  Prev: populating-spatial-columns,  Up: creating-a-spatially-enabled-mysql-database

22.4.5 Fetching Spatial Data
----------------------------

Geometry values stored in a table can be fetched in internal format.
You can also convert them into WKT or WKB format.

   * Fetching spatial data in internal format:

     Fetching geometry values using internal format can be useful in
     table-to-table transfers:

          CREATE TABLE geom2 (g GEOMETRY) SELECT g FROM geom;

   * Fetching spatial data in WKT format:

     The `AsText()' function converts a geometry from internal format
     into a WKT string.

          SELECT AsText(g) FROM geom;

   * Fetching spatial data in WKB format:

     The `AsBinary()' function converts a geometry from internal format
     into a `BLOB' containing the WKB value.

          SELECT AsBinary(g) FROM geom;


File: manual.info,  Node: analysing-spatial-information,  Next: optimizing-spatial-analysis,  Prev: creating-a-spatially-enabled-mysql-database,  Up: spatial-extensions

22.5 Analyzing Spatial Information
==================================

* Menu:

* functions-to-convert-geometries-between-formats::  Geometry Format Conversion Functions
* geometry-property-functions::  `Geometry' Functions
* functions-that-create-new-geometries-from-existing-ones::  Functions That Create New Geometries from Existing Ones
* functions-for-testing-spatial-relations-between-geometric-objects::  Functions for Testing Spatial Relations Between Geometric Objects
* relations-on-geometry-mbr::    Relations on Geometry Minimal Bounding Rectangles (MBRs)
* functions-that-test-spatial-relationships-between-geometries::  Functions That Test Spatial Relationships Between Geometries

After populating spatial columns with values, you are ready to query
and analyze them. MySQL provides a set of functions to perform various
operations on spatial data. These functions can be grouped into four
major categories according to the type of operation they perform:

   * Functions that convert geometries between various formats

   * Functions that provide access to qualitative or quantitative
     properties of a geometry

   * Functions that describe relations between two geometries

   * Functions that create new geometries from existing ones

Spatial analysis functions can be used in many contexts, such as:

   * Any interactive SQL program, such as `mysql' or MySQL Query Browser

   * Application programs written in any language that supports a MySQL
     client API


File: manual.info,  Node: functions-to-convert-geometries-between-formats,  Next: geometry-property-functions,  Prev: analysing-spatial-information,  Up: analysing-spatial-information

22.5.1 Geometry Format Conversion Functions
-------------------------------------------

MySQL supports the following functions for converting geometry values
between internal format and either WKT or WKB format:

   *  `AsBinary(G)', `AsWKB(G)'

     Converts a value in internal geometry format to its WKB
     representation and returns the binary result.

          SELECT AsBinary(g) FROM geom;

   *  `AsText(G)', `AsWKT(G)'

     Converts a value in internal geometry format to its WKT
     representation and returns the string result.

          mysql> SET @g = 'LineString(1 1,2 2,3 3)';
          mysql> SELECT AsText(GeomFromText(@g));
          +--------------------------+
          | AsText(GeomFromText(@g)) |
          +--------------------------+
          | LINESTRING(1 1,2 2,3 3)  |
          +--------------------------+

   * `GeomFromText(WKT[,SRID])'

     Converts a string value from its WKT representation into internal
     geometry format and returns the result. A number of type-specific
     functions are also supported, such as `PointFromText()' and
     `LineFromText()'. See *Note gis-wkt-functions::.

   * `GeomFromWKB(WKB[,SRID])'

     Converts a binary value from its WKB representation into internal
     geometry format and returns the result. A number of type-specific
     functions are also supported, such as `PointFromWKB()' and
     `LineFromWKB()'. See *Note gis-wkb-functions::.


File: manual.info,  Node: geometry-property-functions,  Next: functions-that-create-new-geometries-from-existing-ones,  Prev: functions-to-convert-geometries-between-formats,  Up: analysing-spatial-information

22.5.2 `Geometry' Functions
---------------------------

* Menu:

* general-geometry-property-functions::  General Geometry Functions
* point-property-functions::     `Point' Functions
* linestring-property-functions::  `LineString' Functions
* multilinestring-property-functions::  `MultiLineString' Functions
* polygon-property-functions::   `Polygon' Functions
* multipolygon-property-functions::  `MultiPolygon' Functions
* geometrycollection-property-functions::  `GeometryCollection' Functions

Each function that belongs to this group takes a geometry value as its
argument and returns some quantitative or qualitative property of the
geometry. Some functions restrict their argument type. Such functions
return `NULL' if the argument is of an incorrect geometry type. For
example, `Area()' returns `NULL' if the object type is neither
`Polygon' nor `MultiPolygon'.


File: manual.info,  Node: general-geometry-property-functions,  Next: point-property-functions,  Prev: geometry-property-functions,  Up: geometry-property-functions

22.5.2.1 General Geometry Functions
...................................

The functions listed in this section do not restrict their argument and
accept a geometry value of any type.

   *  `Dimension(G)'

     Returns the inherent dimension of the geometry value G. The result
     can be -1, 0, 1, or 2. The meaning of these values is given in
     *Note gis-class-geometry::.

          mysql> SELECT Dimension(GeomFromText('LineString(1 1,2 2)'));
          +------------------------------------------------+
          | Dimension(GeomFromText('LineString(1 1,2 2)')) |
          +------------------------------------------------+
          |                                              1 |
          +------------------------------------------------+

   *  `Envelope(G)'

     Returns the Minimum Bounding Rectangle (MBR) for the geometry
     value G. The result is returned as a `Polygon' value.

     The polygon is defined by the corner points of the bounding box:

          POLYGON((MINX MINY, MAXX MINY, MAXX MAXY, MINX MAXY, MINX MINY))

          mysql> SELECT AsText(Envelope(GeomFromText('LineString(1 1,2 2)')));
          +-------------------------------------------------------+
          | AsText(Envelope(GeomFromText('LineString(1 1,2 2)'))) |
          +-------------------------------------------------------+
          | POLYGON((1 1,2 1,2 2,1 2,1 1))                        |
          +-------------------------------------------------------+

   *  `GeometryType(G)'

     Returns as a string the name of the geometry type of which the
     geometry instance G is a member. The name corresponds to one of
     the instantiable `Geometry' subclasses.

          mysql> SELECT GeometryType(GeomFromText('POINT(1 1)'));
          +------------------------------------------+
          | GeometryType(GeomFromText('POINT(1 1)')) |
          +------------------------------------------+
          | POINT                                    |
          +------------------------------------------+

   *  `SRID(G)'

     Returns an integer indicating the Spatial Reference System ID for
     the geometry value G.

     In MySQL, the SRID value is just an integer associated with the
     geometry value. All calculations are done assuming Euclidean
     (planar) geometry.

          mysql> SELECT SRID(GeomFromText('LineString(1 1,2 2)',101));
          +-----------------------------------------------+
          | SRID(GeomFromText('LineString(1 1,2 2)',101)) |
          +-----------------------------------------------+
          |                                           101 |
          +-----------------------------------------------+

The OpenGIS specification also defines the following functions, which
MySQL does not implement:

   *  `Boundary(G)'

     Returns a geometry that is the closure of the combinatorial
     boundary of the geometry value G.

   *  `IsEmpty(G)'

     Returns 1 if the geometry value G is the empty geometry, 0 if it
     is not empty, and -1 if the argument is `NULL'. If the geometry is
     empty, it represents the empty point set.

   *  `IsSimple(G)'

     Currently, this function is a placeholder and should not be used.
     If implemented, its behavior will be as described in the next
     paragraph.

     Returns 1 if the geometry value G has no anomalous geometric
     points, such as self-intersection or self-tangency.  `IsSimple()'
     returns 0 if the argument is not simple, and -1 if it is `NULL'.

     The description of each instantiable geometric class given earlier
     in the chapter includes the specific conditions that cause an
     instance of that class to be classified as not simple. (See *Note
     gis-geometry-class-hierarchy::.)


File: manual.info,  Node: point-property-functions,  Next: linestring-property-functions,  Prev: general-geometry-property-functions,  Up: geometry-property-functions

22.5.2.2 `Point' Functions
..........................

A `Point' consists of X and Y coordinates, which may be obtained using
the following functions:

   *  `X(P)'

     Returns the X-coordinate value for the point P as a
     double-precision number.

          mysql> SET @pt = 'Point(56.7 53.34)';
          mysql> SELECT X(GeomFromText(@pt));
          +----------------------+
          | X(GeomFromText(@pt)) |
          +----------------------+
          |                 56.7 |
          +----------------------+

   *  `Y(P)'

     Returns the Y-coordinate value for the point P as a
     double-precision number.

          mysql> SET @pt = 'Point(56.7 53.34)';
          mysql> SELECT Y(GeomFromText(@pt));
          +----------------------+
          | Y(GeomFromText(@pt)) |
          +----------------------+
          |                53.34 |
          +----------------------+


File: manual.info,  Node: linestring-property-functions,  Next: multilinestring-property-functions,  Prev: point-property-functions,  Up: geometry-property-functions

22.5.2.3 `LineString' Functions
...............................

A `LineString' consists of `Point' values. You can extract particular
points of a `LineString', count the number of points that it contains,
or obtain its length.

   *  `EndPoint(LS)'

     Returns the `Point' that is the endpoint of the `LineString' value
     LS.

          mysql> SET @ls = 'LineString(1 1,2 2,3 3)';
          mysql> SELECT AsText(EndPoint(GeomFromText(@ls)));
          +-------------------------------------+
          | AsText(EndPoint(GeomFromText(@ls))) |
          +-------------------------------------+
          | POINT(3 3)                          |
          +-------------------------------------+

   *  `GLength(LS)'

     Returns as a double-precision number the length of the
     `LineString' value LS in its associated spatial reference.

          mysql> SET @ls = 'LineString(1 1,2 2,3 3)';
          mysql> SELECT GLength(GeomFromText(@ls));
          +----------------------------+
          | GLength(GeomFromText(@ls)) |
          +----------------------------+
          |            2.8284271247462 |
          +----------------------------+

     `GLength()' is a non-standard name. It corresponds to the OpenGIS
     `Length()' function.

   *  `NumPoints(LS)'

     Returns the number of `Point' objects in the `LineString' value LS.

          mysql> SET @ls = 'LineString(1 1,2 2,3 3)';
          mysql> SELECT NumPoints(GeomFromText(@ls));
          +------------------------------+
          | NumPoints(GeomFromText(@ls)) |
          +------------------------------+
          |                            3 |
          +------------------------------+

   *  `PointN(LS,N)'

     Returns the N-th `Point' in the `Linestring' value LS. Points are
     numbered beginning with 1.

          mysql> SET @ls = 'LineString(1 1,2 2,3 3)';
          mysql> SELECT AsText(PointN(GeomFromText(@ls),2));
          +-------------------------------------+
          | AsText(PointN(GeomFromText(@ls),2)) |
          +-------------------------------------+
          | POINT(2 2)                          |
          +-------------------------------------+

   *  `StartPoint(LS)'

     Returns the `Point' that is the start point of the `LineString'
     value LS.

          mysql> SET @ls = 'LineString(1 1,2 2,3 3)';
          mysql> SELECT AsText(StartPoint(GeomFromText(@ls)));
          +---------------------------------------+
          | AsText(StartPoint(GeomFromText(@ls))) |
          +---------------------------------------+
          | POINT(1 1)                            |
          +---------------------------------------+

The OpenGIS specification also defines the following function, which
MySQL does not implement:

   *  `IsRing(LS)'

     Returns 1 if the `LineString' value LS is closed (that is, its
     `StartPoint()' and `EndPoint()' values are the same) and is simple
     (does not pass through the same point more than once). Returns 0 if
     LS is not a ring, and -1 if it is `NULL'.


File: manual.info,  Node: multilinestring-property-functions,  Next: polygon-property-functions,  Prev: linestring-property-functions,  Up: geometry-property-functions

22.5.2.4 `MultiLineString' Functions
....................................

These functions return properties of `MultiLineString' values.

   * `GLength(MLS)'

     Returns as a double-precision number the length of the
     `MultiLineString' value MLS. The length of MLS is equal to the sum
     of the lengths of its elements.

          mysql> SET @mls = 'MultiLineString((1 1,2 2,3 3),(4 4,5 5))';
          mysql> SELECT GLength(GeomFromText(@mls));
          +-----------------------------+
          | GLength(GeomFromText(@mls)) |
          +-----------------------------+
          |             4.2426406871193 |
          +-----------------------------+

     `GLength()' is a non-standard name. It corresponds to the OpenGIS
     `Length()' function.

   *  `IsClosed(MLS)'

     Returns 1 if the `MultiLineString' value MLS is closed (that is,
     the `StartPoint()' and `EndPoint()' values are the same for each
     `LineString' in MLS). Returns 0 if MLS is not closed, and -1 if it
     is `NULL'.

          mysql> SET @mls = 'MultiLineString((1 1,2 2,3 3),(4 4,5 5))';
          mysql> SELECT IsClosed(GeomFromText(@mls));
          +------------------------------+
          | IsClosed(GeomFromText(@mls)) |
          +------------------------------+
          |                            0 |
          +------------------------------+


File: manual.info,  Node: polygon-property-functions,  Next: multipolygon-property-functions,  Prev: multilinestring-property-functions,  Up: geometry-property-functions

22.5.2.5 `Polygon' Functions
............................

These functions return properties of `Polygon' values.

   *  `Area(POLY)'

     Returns as a double-precision number the area of the `Polygon'
     value POLY, as measured in its spatial reference system.

          mysql> SET @poly = 'Polygon((0 0,0 3,3 0,0 0),(1 1,1 2,2 1,1 1))';
          mysql> SELECT Area(GeomFromText(@poly));
          +---------------------------+
          | Area(GeomFromText(@poly)) |
          +---------------------------+
          |                         4 |
          +---------------------------+

   *  `ExteriorRing(POLY)'

     Returns the exterior ring of the `Polygon' value POLY as a
     `LineString'.

          mysql> SET @poly =
              -> 'Polygon((0 0,0 3,3 3,3 0,0 0),(1 1,1 2,2 2,2 1,1 1))';
          mysql> SELECT AsText(ExteriorRing(GeomFromText(@poly)));
          +-------------------------------------------+
          | AsText(ExteriorRing(GeomFromText(@poly))) |
          +-------------------------------------------+
          | LINESTRING(0 0,0 3,3 3,3 0,0 0)           |
          +-------------------------------------------+

   *  `InteriorRingN(POLY,N)'

     Returns the N-th interior ring for the `Polygon' value POLY as a
     `LineString'. Rings are numbered beginning with 1.

          mysql> SET @poly =
              -> 'Polygon((0 0,0 3,3 3,3 0,0 0),(1 1,1 2,2 2,2 1,1 1))';
          mysql> SELECT AsText(InteriorRingN(GeomFromText(@poly),1));
          +----------------------------------------------+
          | AsText(InteriorRingN(GeomFromText(@poly),1)) |
          +----------------------------------------------+
          | LINESTRING(1 1,1 2,2 2,2 1,1 1)              |
          +----------------------------------------------+

   *  `NumInteriorRings(POLY)'

     Returns the number of interior rings in the `Polygon' value POLY.

          mysql> SET @poly =
              -> 'Polygon((0 0,0 3,3 3,3 0,0 0),(1 1,1 2,2 2,2 1,1 1))';
          mysql> SELECT NumInteriorRings(GeomFromText(@poly));
          +---------------------------------------+
          | NumInteriorRings(GeomFromText(@poly)) |
          +---------------------------------------+
          |                                     1 |
          +---------------------------------------+


File: manual.info,  Node: multipolygon-property-functions,  Next: geometrycollection-property-functions,  Prev: polygon-property-functions,  Up: geometry-property-functions

22.5.2.6 `MultiPolygon' Functions
.................................

These functions return properties of `MultiPolygon' values.

   * `Area(MPOLY)'

     Returns as a double-precision number the area of the
     `MultiPolygon' value MPOLY, as measured in its spatial reference
     system.

          mysql> SET @mpoly =
              -> 'MultiPolygon(((0 0,0 3,3 3,3 0,0 0),(1 1,1 2,2 2,2 1,1 1)))';
          mysql> SELECT Area(GeomFromText(@mpoly));
          +----------------------------+
          | Area(GeomFromText(@mpoly)) |
          +----------------------------+
          |                          8 |
          +----------------------------+

The OpenGIS specification also defines the following functions, which
MySQL does not implement:

   *  `Centroid(MPOLY)'

     Returns the mathematical centroid for the `MultiPolygon' value
     MPOLY as a `Point'. The result is not guaranteed to be on the
     `MultiPolygon'.

   * `PointOnSurface(MPOLY)'

     Returns a `Point' value that is guaranteed to be on the
     `MultiPolygon' value MPOLY.


File: manual.info,  Node: geometrycollection-property-functions,  Prev: multipolygon-property-functions,  Up: geometry-property-functions

22.5.2.7 `GeometryCollection' Functions
.......................................

These functions return properties of `GeometryCollation' values.

   *  `GeometryN(GC,N)'

     Returns the N-th geometry in the `GeometryCollection' value GC.
     Geometries are numbered beginning with 1.

          mysql> SET @gc = 'GeometryCollection(Point(1 1),LineString(2 2, 3 3))';
          mysql> SELECT AsText(GeometryN(GeomFromText(@gc),1));
          +----------------------------------------+
          | AsText(GeometryN(GeomFromText(@gc),1)) |
          +----------------------------------------+
          | POINT(1 1)                             |
          +----------------------------------------+

   *  `NumGeometries(GC)'

     Returns the number of geometries in the `GeometryCollection' value
     GC.

          mysql> SET @gc = 'GeometryCollection(Point(1 1),LineString(2 2, 3 3))';
          mysql> SELECT NumGeometries(GeomFromText(@gc));
          +----------------------------------+
          | NumGeometries(GeomFromText(@gc)) |
          +----------------------------------+
          |                                2 |
          +----------------------------------+


File: manual.info,  Node: functions-that-create-new-geometries-from-existing-ones,  Next: functions-for-testing-spatial-relations-between-geometric-objects,  Prev: geometry-property-functions,  Up: analysing-spatial-information

22.5.3 Functions That Create New Geometries from Existing Ones
--------------------------------------------------------------

* Menu:

* functions-that-produce-new-geometries::  Geometry Functions That Produce New Geometries
* spatial-operators::            Spatial Operators

The following sections describe functions that take geometry values as
arguments and return new geometry values.


File: manual.info,  Node: functions-that-produce-new-geometries,  Next: spatial-operators,  Prev: functions-that-create-new-geometries-from-existing-ones,  Up: functions-that-create-new-geometries-from-existing-ones

22.5.3.1 Geometry Functions That Produce New Geometries
.......................................................

*Note geometry-property-functions::, discusses several functions that
construct new geometries from existing ones. See that section for
descriptions of these functions:

   * `Envelope(G)'

   * `StartPoint(LS)'

   * `EndPoint(LS)'

   * `PointN(LS,N)'

   * `ExteriorRing(POLY)'

   * `InteriorRingN(POLY,N)'

   * `GeometryN(GC,N)'


File: manual.info,  Node: spatial-operators,  Prev: functions-that-produce-new-geometries,  Up: functions-that-create-new-geometries-from-existing-ones

22.5.3.2 Spatial Operators
..........................

OpenGIS proposes a number of other functions that can produce
geometries. They are designed to implement spatial operators.

These functions are not implemented in MySQL. They may appear in future
releases.

   *  `Buffer(G,D)'

     Returns a geometry that represents all points whose distance from
     the geometry value G is less than or equal to a distance of D.

   *  `ConvexHull(G)'

     Returns a geometry that represents the convex hull of the geometry
     value G.

   *  `Difference(G1,G2)'

     Returns a geometry that represents the point set difference of the
     geometry value G1 with G2.

   *  `Intersection(G1,G2)'

     Returns a geometry that represents the point set intersection of
     the geometry values G1 with G2.

   *  `SymDifference(G1,G2)'

     Returns a geometry that represents the point set symmetric
     difference of the geometry value G1 with G2.

   *  `Union(G1,G2)'

     Returns a geometry that represents the point set union of the
     geometry values G1 and G2.


File: manual.info,  Node: functions-for-testing-spatial-relations-between-geometric-objects,  Next: relations-on-geometry-mbr,  Prev: functions-that-create-new-geometries-from-existing-ones,  Up: analysing-spatial-information

22.5.4 Functions for Testing Spatial Relations Between Geometric Objects
------------------------------------------------------------------------

The functions described in these sections take two geometries as input
parameters and return a qualitative or quantitative relation between
them.


File: manual.info,  Node: relations-on-geometry-mbr,  Next: functions-that-test-spatial-relationships-between-geometries,  Prev: functions-for-testing-spatial-relations-between-geometric-objects,  Up: analysing-spatial-information

22.5.5 Relations on Geometry Minimal Bounding Rectangles (MBRs)
---------------------------------------------------------------

MySQL provides several functions that test relations between minimal
bounding rectangles of two geometries `g1' and `g2'. The return values
1 and 0 indicate true and false, respectively.

   *  `MBRContains(G1,G2)'

     Returns 1 or 0 to indicate whether the Minimum Bounding Rectangle
     of G1 contains the Minimum Bounding Rectangle of G2.  This tests
     the opposite relationship as `MBRWithin()'.

          mysql> SET @g1 = GeomFromText('Polygon((0 0,0 3,3 3,3 0,0 0))');
          mysql> SET @g2 = GeomFromText('Point(1 1)');
          mysql> SELECT MBRContains(@g1,@g2), MBRContains(@g2,@g1);
          ----------------------+----------------------+
          | MBRContains(@g1,@g2) | MBRContains(@g2,@g1) |
          +----------------------+----------------------+
          |                    1 |                    0 |
          +----------------------+----------------------+

   *  `MBRDisjoint(G1,G2)'

     Returns 1 or 0 to indicate whether the Minimum Bounding Rectangles
     of the two geometries G1 and G2 are disjoint (do not intersect).

   *  `MBREqual(G1,G2)'

     Returns 1 or 0 to indicate whether the Minimum Bounding Rectangles
     of the two geometries G1 and G2 are the same.

   *  `MBRIntersects(G1,G2)'

     Returns 1 or 0 to indicate whether the Minimum Bounding Rectangles
     of the two geometries G1 and G2 intersect.

   *  `MBROverlaps(G1,G2)'

     Returns 1 or 0 to indicate whether the Minimum Bounding Rectangles
     of the two geometries G1 and G2 overlap. The term _spatially
     overlaps_ is used if two geometries intersect and their
     intersection results in a geometry of the same dimension but not
     equal to either of the given geometries.

   *  `MBRTouches(G1,G2)'

     Returns 1 or 0 to indicate whether the Minimum Bounding Rectangles
     of the two geometries G1 and G2 touch. Two geometries _spatially
     touch_ if the interiors of the geometries do not intersect, but
     the boundary of one of the geometries intersects either the
     boundary or the interior of the other.

   *  `MBRWithin(G1,G2)'

     Returns 1 or 0 to indicate whether the Minimum Bounding Rectangle
     of G1 is within the Minimum Bounding Rectangle of G2.  This tests
     the opposite relationship as `MBRContains()'.

          mysql> SET @g1 = GeomFromText('Polygon((0 0,0 3,3 3,3 0,0 0))');
          mysql> SET @g2 = GeomFromText('Polygon((0 0,0 5,5 5,5 0,0 0))');
          mysql> SELECT MBRWithin(@g1,@g2), MBRWithin(@g2,@g1);
          +--------------------+--------------------+
          | MBRWithin(@g1,@g2) | MBRWithin(@g2,@g1) |
          +--------------------+--------------------+
          |                  1 |                  0 |
          +--------------------+--------------------+


File: manual.info,  Node: functions-that-test-spatial-relationships-between-geometries,  Prev: relations-on-geometry-mbr,  Up: analysing-spatial-information

22.5.6 Functions That Test Spatial Relationships Between Geometries
-------------------------------------------------------------------

The OpenGIS specification defines the following functions. They test
the relationship between two geometry values `g1' and `g2'.

The return values 1 and 0 indicate true and false, respectively.

*Note*:

Currently, MySQL does not implement these functions according to the
specification. Those that are implemented return the same result as the
corresponding MBR-based functions. This includes functions in the
following list other than `Distance()' and `Related()'.

These functions may be implemented in future releases with full support
for spatial analysis, not just MBR-based support.

   *  `Contains(G1,G2)'

     Returns 1 or 0 to indicate whether G1 completely contains G2. This
     tests the opposite relationship as `Within()'.

   *  `Crosses(G1,G2)'

     Returns 1 if G1 spatially crosses G2. Returns `NULL' if `g1' is a
     `Polygon' or a `MultiPolygon', or if G2 is a `Point' or a
     `MultiPoint'. Otherwise, returns 0.

     The term _spatially crosses_ denotes a spatial relation between
     two given geometries that has the following properties:

        * The two geometries intersect

        * Their intersection results in a geometry that has a dimension
          that is one less than the maximum dimension of the two given
          geometries

        * Their intersection is not equal to either of the two given
          geometries

   *  `Disjoint(G1,G2)'

     Returns 1 or 0 to indicate whether G1 is spatially disjoint from
     (does not intersect) G2.

   *  `Distance(G1,G2)'

     Returns as a double-precision number the shortest distance between
     any two points in the two geometries.

   *  `Equals(G1,G2)'

     Returns 1 or 0 to indicate whether G1 is spatially equal to G2.

   *  `Intersects(G1,G2)'

     Returns 1 or 0 to indicate whether G1 spatially intersects G2.

   *  `Overlaps(G1,G2)'

     Returns 1 or 0 to indicate whether G1 spatially overlaps G2. The
     term _spatially overlaps_ is used if two geometries intersect and
     their intersection results in a geometry of the same dimension but
     not equal to either of the given geometries.

   *  `Related(G1,G2,PATTERN_MATRIX)'

     Returns 1 or 0 to indicate whether the spatial relationship
     specified by PATTERN_MATRIX exists between G1 and G2. Returns -1
     if the arguments are `NULL'. The pattern matrix is a string. Its
     specification will be noted here if this function is implemented.

   *  `Touches(G1,G2)'

     Returns 1 or 0 to indicate whether G1 spatially touches G2. Two
     geometries _spatially touch_ if the interiors of the geometries do
     not intersect, but the boundary of one of the geometries
     intersects either the boundary or the interior of the other.

   *  `Within(G1,G2)'

     Returns 1 or 0 to indicate whether G1 is spatially within G2. This
     tests the opposite relationship as `Contains()'.


File: manual.info,  Node: optimizing-spatial-analysis,  Next: mysql-gis-conformance-and-compatibility,  Prev: analysing-spatial-information,  Up: spatial-extensions

22.6 Optimizing Spatial Analysis
================================

* Menu:

* creating-spatial-indexes::     Creating Spatial Indexes
* using-a-spatial-index::        Using a Spatial Index

Search operations in non-spatial databases can be optimized using
`SPATIAL' indexes. This is true for spatial databases as well. With the
help of a great variety of multi-dimensional indexing methods that have
previously been designed, it is possible to optimize spatial searches.
The most typical of these are:

   * Point queries that search for all objects that contain a given
     point

   * Region queries that search for all objects that overlap a given
     region

MySQL uses *R-Trees with quadratic splitting* for `SPATIAL' indexes on
spatial columns. A `SPATIAL' index is built using the MBR of a
geometry. For most geometries, the MBR is a minimum rectangle that
surrounds the geometries. For a horizontal or a vertical linestring,
the MBR is a rectangle degenerated into the linestring. For a point,
the MBR is a rectangle degenerated into the point.

It is also possible to create normal indexes on spatial columns.  In a
non-`SPATIAL' index, you must declare a prefix for any spatial column
except for `POINT' columns.

`MyISAM' supports both `SPATIAL' and non-`SPATIAL' indexes. Other
storage engines support non-`SPATIAL' indexes, as described in *Note
create-index::.


File: manual.info,  Node: creating-spatial-indexes,  Next: using-a-spatial-index,  Prev: optimizing-spatial-analysis,  Up: optimizing-spatial-analysis

22.6.1 Creating Spatial Indexes
-------------------------------

MySQL can create spatial indexes using syntax similar to that for
creating regular indexes, but extended with the `SPATIAL' keyword.
Currently, columns in spatial indexes must be declared `NOT NULL'.  The
following examples demonstrate how to create spatial indexes:

   * With `CREATE TABLE':

          CREATE TABLE geom (g GEOMETRY NOT NULL, SPATIAL INDEX(g));

   * With `ALTER TABLE':

          ALTER TABLE geom ADD SPATIAL INDEX(g);

   * With `CREATE INDEX':

          CREATE SPATIAL INDEX sp_index ON geom (g);

For `MyISAM' tables, `SPATIAL INDEX' creates an R-tree index. For
storage engines that support non-spatial indexing of spatial columns,
the engine creates a B-tree index. A B-tree index on spatial values
will be useful for exact-value lookups, but not for range scans.

For more information on indexing spatial columns, see *Note
create-index::.

To drop spatial indexes, use `ALTER TABLE' or `DROP INDEX':

   * With `ALTER TABLE':

          ALTER TABLE geom DROP INDEX g;

   * With `DROP INDEX':

          DROP INDEX sp_index ON geom;

Example: Suppose that a table `geom' contains more than 32,000
geometries, which are stored in the column `g' of type `GEOMETRY'. The
table also has an `AUTO_INCREMENT' column `fid' for storing object ID
values.

     mysql> DESCRIBE geom;
     +-------+----------+------+-----+---------+----------------+
     | Field | Type     | Null | Key | Default | Extra          |
     +-------+----------+------+-----+---------+----------------+
     | fid   | int(11)  |      | PRI | NULL    | auto_increment |
     | g     | geometry |      |     |         |                |
     +-------+----------+------+-----+---------+----------------+
     2 rows in set (0.00 sec)

     mysql> SELECT COUNT(*) FROM geom;
     +----------+
     | count(*) |
     +----------+
     |    32376 |
     +----------+
     1 row in set (0.00 sec)

To add a spatial index on the column `g', use this statement:

     mysql> ALTER TABLE geom ADD SPATIAL INDEX(g);
     Query OK, 32376 rows affected (4.05 sec)
     Records: 32376  Duplicates: 0  Warnings: 0


File: manual.info,  Node: using-a-spatial-index,  Prev: creating-spatial-indexes,  Up: optimizing-spatial-analysis

22.6.2 Using a Spatial Index
----------------------------

The optimizer investigates whether available spatial indexes can be
involved in the search for queries that use a function such as
`MBRContains()' or `MBRWithin()' in the `WHERE' clause. The following
query finds all objects that are in the given rectangle:

     mysql> SET @poly =
         -> 'Polygon((30000 15000,
                                    31000 15000,
                                    31000 16000,
                                    30000 16000,
                                    30000 15000))';
     mysql> SELECT fid,AsText(g) FROM geom WHERE
         -> MBRContains(GeomFromText(@poly),g);
     +-----+---------------------------------------------------------------+
     | fid | AsText(g)                                                     |
     +-----+---------------------------------------------------------------+
     |  21 | LINESTRING(30350.4 15828.8,30350.6 15845,30333.8 15845,30 ... |
     |  22 | LINESTRING(30350.6 15871.4,30350.6 15887.8,30334 15887.8, ... |
     |  23 | LINESTRING(30350.6 15914.2,30350.6 15930.4,30334 15930.4, ... |
     |  24 | LINESTRING(30290.2 15823,30290.2 15839.4,30273.4 15839.4, ... |
     |  25 | LINESTRING(30291.4 15866.2,30291.6 15882.4,30274.8 15882. ... |
     |  26 | LINESTRING(30291.6 15918.2,30291.6 15934.4,30275 15934.4, ... |
     | 249 | LINESTRING(30337.8 15938.6,30337.8 15946.8,30320.4 15946. ... |
     |   1 | LINESTRING(30250.4 15129.2,30248.8 15138.4,30238.2 15136. ... |
     |   2 | LINESTRING(30220.2 15122.8,30217.2 15137.8,30207.6 15136, ... |
     |   3 | LINESTRING(30179 15114.4,30176.6 15129.4,30167 15128,3016 ... |
     |   4 | LINESTRING(30155.2 15121.4,30140.4 15118.6,30142 15109,30 ... |
     |   5 | LINESTRING(30192.4 15085,30177.6 15082.2,30179.2 15072.4, ... |
     |   6 | LINESTRING(30244 15087,30229 15086.2,30229.4 15076.4,3024 ... |
     |   7 | LINESTRING(30200.6 15059.4,30185.6 15058.6,30186 15048.8, ... |
     |  10 | LINESTRING(30179.6 15017.8,30181 15002.8,30190.8 15003.6, ... |
     |  11 | LINESTRING(30154.2 15000.4,30168.6 15004.8,30166 15014.2, ... |
     |  13 | LINESTRING(30105 15065.8,30108.4 15050.8,30118 15053,3011 ... |
     | 154 | LINESTRING(30276.2 15143.8,30261.4 15141,30263 15131.4,30 ... |
     | 155 | LINESTRING(30269.8 15084,30269.4 15093.4,30258.6 15093,30 ... |
     | 157 | LINESTRING(30128.2 15011,30113.2 15010.2,30113.6 15000.4, ... |
     +-----+---------------------------------------------------------------+
     20 rows in set (0.00 sec)

Use `EXPLAIN' to check the way this query is executed:

     mysql> SET @poly =
         -> 'Polygon((30000 15000,
                                    31000 15000,
                                    31000 16000,
                                    30000 16000,
                                    30000 15000))';
     mysql> EXPLAIN SELECT fid,AsText(g) FROM geom WHERE
         -> MBRContains(GeomFromText(@poly),g)\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: geom
              type: range
     possible_keys: g
               key: g
           key_len: 32
               ref: NULL
              rows: 50
             Extra: Using where
     1 row in set (0.00 sec)

Check what would happen without a spatial index:

     mysql> SET @poly =
         -> 'Polygon((30000 15000,
                                    31000 15000,
                                    31000 16000,
                                    30000 16000,
                                    30000 15000))';
     mysql> EXPLAIN SELECT fid,AsText(g) FROM g IGNORE INDEX (g) WHERE
         -> MBRContains(GeomFromText(@poly),g)\G
     *************************** 1. row ***************************
                id: 1
       select_type: SIMPLE
             table: geom
              type: ALL
     possible_keys: NULL
               key: NULL
           key_len: NULL
               ref: NULL
              rows: 32376
             Extra: Using where
     1 row in set (0.00 sec)

Executing the `SELECT' statement without the spatial index yields the
same result but causes the execution time to rise from 0.00 seconds to
0.46 seconds:

     mysql> SET @poly =
         -> 'Polygon((30000 15000,
                                    31000 15000,
                                    31000 16000,
                                    30000 16000,
                                    30000 15000))';
     mysql> SELECT fid,AsText(g) FROM geom IGNORE INDEX (g) WHERE
         -> MBRContains(GeomFromText(@poly),g);
     +-----+---------------------------------------------------------------+
     | fid | AsText(g)                                                     |
     +-----+---------------------------------------------------------------+
     |   1 | LINESTRING(30250.4 15129.2,30248.8 15138.4,30238.2 15136. ... |
     |   2 | LINESTRING(30220.2 15122.8,30217.2 15137.8,30207.6 15136, ... |
     |   3 | LINESTRING(30179 15114.4,30176.6 15129.4,30167 15128,3016 ... |
     |   4 | LINESTRING(30155.2 15121.4,30140.4 15118.6,30142 15109,30 ... |
     |   5 | LINESTRING(30192.4 15085,30177.6 15082.2,30179.2 15072.4, ... |
     |   6 | LINESTRING(30244 15087,30229 15086.2,30229.4 15076.4,3024 ... |
     |   7 | LINESTRING(30200.6 15059.4,30185.6 15058.6,30186 15048.8, ... |
     |  10 | LINESTRING(30179.6 15017.8,30181 15002.8,30190.8 15003.6, ... |
     |  11 | LINESTRING(30154.2 15000.4,30168.6 15004.8,30166 15014.2, ... |
     |  13 | LINESTRING(30105 15065.8,30108.4 15050.8,30118 15053,3011 ... |
     |  21 | LINESTRING(30350.4 15828.8,30350.6 15845,30333.8 15845,30 ... |
     |  22 | LINESTRING(30350.6 15871.4,30350.6 15887.8,30334 15887.8, ... |
     |  23 | LINESTRING(30350.6 15914.2,30350.6 15930.4,30334 15930.4, ... |
     |  24 | LINESTRING(30290.2 15823,30290.2 15839.4,30273.4 15839.4, ... |
     |  25 | LINESTRING(30291.4 15866.2,30291.6 15882.4,30274.8 15882. ... |
     |  26 | LINESTRING(30291.6 15918.2,30291.6 15934.4,30275 15934.4, ... |
     | 154 | LINESTRING(30276.2 15143.8,30261.4 15141,30263 15131.4,30 ... |
     | 155 | LINESTRING(30269.8 15084,30269.4 15093.4,30258.6 15093,30 ... |
     | 157 | LINESTRING(30128.2 15011,30113.2 15010.2,30113.6 15000.4, ... |
     | 249 | LINESTRING(30337.8 15938.6,30337.8 15946.8,30320.4 15946. ... |
     +-----+---------------------------------------------------------------+
     20 rows in set (0.46 sec)

In future releases, spatial indexes may also be used for optimizing
other functions. See *Note
functions-for-testing-spatial-relations-between-geometric-objects::.


File: manual.info,  Node: mysql-gis-conformance-and-compatibility,  Prev: optimizing-spatial-analysis,  Up: spatial-extensions

22.7 MySQL Conformance and Compatibility
========================================

MySQL does not yet implement the following GIS features:

   * Additional Metadata Views

     OpenGIS specifications propose several additional metadata views.
     For example, a system view named `GEOMETRY_COLUMNS' contains a
     description of geometry columns, one row for each geometry column
     in the database.

   * The OpenGIS function `Length()' on `LineString' and
     `MultiLineString' currently should be called in MySQL as
     `GLength()'

     The problem is that there is an existing SQL function `Length()'
     that calculates the length of string values, and sometimes it is
     not possible to distinguish whether the function is called in a
     textual or spatial context. We need either to solve this somehow,
     or decide on another function name.


File: manual.info,  Node: stored-procedures,  Next: triggers,  Prev: spatial-extensions,  Up: Top

23 Stored Procedures and Functions
**********************************

* Menu:

* stored-procedure-privileges::  Stored Routines and the Grant Tables
* stored-procedure-syntax::      Stored Routine Syntax
* stored-procedure-last-insert-id::  Stored Procedures, Functions, Triggers, and `LAST_INSERT_ID()'
* stored-procedure-logging::     Binary Logging of Stored Routines and Triggers

Stored routines (procedures and functions) are supported in MySQL 5.1.
A stored procedure is a set of SQL statements that can be stored in the
server. Once this has been done, clients don't need to keep reissuing
the individual statements but can refer to the stored procedure instead.

Answers to some questions that are commonly asked regarding stored
routines in MySQL can be found in *Note faqs-stored-procs::.

MySQL Enterprise

For expert advice on using stored procedures and functions subscribe to
the MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

Some situations where stored routines can be particularly useful:

   * When multiple client applications are written in different
     languages or work on different platforms, but need to perform the
     same database operations.

   * When security is paramount. Banks, for example, use stored
     procedures and functions for all common operations. This provides
     a consistent and secure environment, and routines can ensure that
     each operation is properly logged. In such a setup, applications
     and users would have no access to the database tables directly,
     but can only execute specific stored routines.

Stored routines can provide improved performance because less
information needs to be sent between the server and the client. The
tradeoff is that this does increase the load on the database server
because more of the work is done on the server side and less is done on
the client (application) side. Consider this if many client machines
(such as Web servers) are serviced by only one or a few database
servers.

Stored routines also allow you to have libraries of functions in the
database server. This is a feature shared by modern application
languages that allow such design internally (for example, by using
classes). Using these client application language features is
beneficial for the programmer even outside the scope of database use.

MySQL follows the SQL:2003 syntax for stored routines, which is also
used by IBM's DB2.

The MySQL implementation of stored routines is still in progress.  All
syntax described in this chapter is supported and any limitations and
extensions are documented where appropriate. Further discussion of
restrictions on use of stored routines is given in *Note
routine-restrictions::.

Binary logging for stored routines takes place as described in *Note
stored-procedure-logging::.

Recursive stored procedures are disabled by default, but can be enabled
on the server by setting the `max_sp_recursion_depth' server system
variable to a nonzero value. Stored procedure recursion increases the
demand on thread stack space. If you increase the value of
`max_sp_recursion_depth', it may be necessary to increase thread stack
size by increasing the value of `thread_stack' at server startup. See
*Note server-system-variables::, for more information.

Stored functions cannot be recursive. See *Note routine-restrictions::.


File: manual.info,  Node: stored-procedure-privileges,  Next: stored-procedure-syntax,  Prev: stored-procedures,  Up: stored-procedures

23.1 Stored Routines and the Grant Tables
=========================================

Stored routines require the `proc' table in the `mysql' database. This
table is created during the MySQL 5.1 installation procedure. If you are
upgrading to MySQL 5.1 from an earlier version, be sure to update your
grant tables to make sure that the `proc' table exists. See *Note
mysql-upgrade::.

The server manipulates the `mysql.proc' table in response to statements
that create, alter, or drop stored routines. It is not supported that
the server will notice manual manipulation of this table.

The MySQL grant system takes stored routines into account as follows:

   * The `CREATE ROUTINE' privilege is needed to create stored routines.

   * The `ALTER ROUTINE' privilege is needed to alter or drop stored
     routines. This privilege is granted automatically to the creator
     of a routine if necessary, and dropped when the routine creator
     drops the routine.

   * The `EXECUTE' privilege is required to execute stored routines.
     However, this privilege is granted automatically to the creator of
     a routine if necessary (and dropped when the creator drops the
     routine). Also, the default `SQL SECURITY' characteristic for a
     routine is `DEFINER', which enables users who have access to the
     database with which the routine is associated to execute the
     routine.

   * If the `automatic_sp_privileges' system variable is 0, the
     `EXECUTE' and `ALTER ROUTINE' privileges are not automatically
     granted and dropped.


File: manual.info,  Node: stored-procedure-syntax,  Next: stored-procedure-last-insert-id,  Prev: stored-procedure-privileges,  Up: stored-procedures

23.2 Stored Routine Syntax
==========================

* Menu:

* create-function::              `CREATE FUNCTION' Syntax
* create-procedure::             `CREATE PROCEDURE' and `CREATE FUNCTION' Syntax
* alter-procedure::              `ALTER PROCEDURE' and `ALTER FUNCTION' Syntax
* drop-function::                `DROP FUNCTION' Syntax
* drop-procedure::               `DROP PROCEDURE' and `DROP FUNCTION' Syntax
* call::                         `CALL' Statement Syntax
* begin-end::                    `BEGIN ... END' Compound Statement Syntax
* declare::                      `DECLARE' Statement Syntax
* variables-in-stored-procedures::  Variables in Stored Routines
* conditions-and-handlers::      Conditions and Handlers
* cursors::                      Cursors
* flow-control-constructs::      Flow Control Constructs
* return::                       `RETURN' Statement Syntax

A stored routine is either a procedure or a function. Stored routines
are created with `CREATE PROCEDURE' and `CREATE FUNCTION' statements. A
procedure is invoked using a `CALL' statement, and can only pass back
values using output variables. A function can be called from inside a
statement just like any other function (that is, by invoking the
function's name), and can return a scalar value.  Stored routines may
call other stored routines.

A stored procedure or function is associated with a particular
database. This has several implications:

   * When the routine is invoked, an implicit `USE DB_NAME' is
     performed (and undone when the routine terminates). `USE'
     statements within stored routines are disallowed.

   * You can qualify routine names with the database name. This can be
     used to refer to a routine that is not in the current database.
     For example, to invoke a stored procedure `p' or function `f' that
     is associated with the `test' database, you can say `CALL
     test.p()' or `test.f()'.

   * When a database is dropped, all stored routines associated with it
     are dropped as well.

MySQL supports the very useful extension that allows the use of regular
`SELECT' statements (that is, without using cursors or local variables)
inside a stored procedure. The result set of such a query is simply
sent directly to the client.  Multiple `SELECT' statements generate
multiple result sets, so the client must use a MySQL client library that
supports multiple result sets. This means the client must use a client
library from a version of MySQL at least as recent as 4.1.  The client
should also specify the `CLIENT_MULTI_RESULTS' option when it connects.
For C programs, this can be done with the *Note `mysql_real_connect()':
mysql-real-connect. C API function. See *Note mysql-real-connect::, and
*Note c-api-multiple-queries::.

MySQL Enterprise

MySQL Enterprise subscribers will find numerous articles about stored
routines in the MySQL Enterprise Knowledge Base. Access to this
collection of articles is one of the advantages of subscribing to MySQL
Enterprise. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

The following sections describe the syntax used to create, alter, drop,
and invoke stored procedures and functions.


File: manual.info,  Node: create-function,  Next: create-procedure,  Prev: stored-procedure-syntax,  Up: stored-procedure-syntax

23.2.1 `CREATE FUNCTION' Syntax
-------------------------------

The `CREATE FUNCTION' statement is used to create stored functions and
user-defined functions (UDFs):

   * For information about creating stored functions, see *Note
     create-procedure::.

   * For information about creating user-defined functions, see *Note
     create-function-udf::.


File: manual.info,  Node: create-procedure,  Next: alter-procedure,  Prev: create-function,  Up: stored-procedure-syntax

23.2.2 `CREATE PROCEDURE' and `CREATE FUNCTION' Syntax
------------------------------------------------------

     CREATE
         [DEFINER = { USER | CURRENT_USER }]
         PROCEDURE SP_NAME ([PROC_PARAMETER[,...]])
         [CHARACTERISTIC ...] ROUTINE_BODY

     CREATE
         [DEFINER = { USER | CURRENT_USER }]
         FUNCTION SP_NAME ([FUNC_PARAMETER[,...]])
         RETURNS TYPE
         [CHARACTERISTIC ...] ROUTINE_BODY

     PROC_PARAMETER:
         [ IN | OUT | INOUT ] PARAM_NAME TYPE

     FUNC_PARAMETER:
         PARAM_NAME TYPE

     TYPE:
         ANY VALID MYSQL DATA TYPE

     CHARACTERISTIC:
         LANGUAGE SQL
       | [NOT] DETERMINISTIC
       | { CONTAINS SQL | NO SQL | READS SQL DATA | MODIFIES SQL DATA }
       | SQL SECURITY { DEFINER | INVOKER }
       | COMMENT 'STRING'

     ROUTINE_BODY:
         VALID SQL PROCEDURE STATEMENT

These statements create stored routines. By default, a routine is
associated with the default database. To associate the routine
explicitly with a given database, specify the name as DB_NAME.SP_NAME
when you create it.

To execute these statements, it is necessary to have the `CREATE
ROUTINE' privilege. If binary logging is enabled, the `CREATE FUNCTION'
statement might also require the `SUPER' privilege, as described in
*Note stored-procedure-logging::. MySQL automatically grants the `ALTER
ROUTINE' and `EXECUTE' privileges to the routine creator.

The `DEFINER' and `SQL SECURITY' clauses specify the security context
to be used when checking access privileges at routine execution time,
as described later.

If the routine name is the same as the name of a built-in SQL function,
you must use a space between the name and the following parenthesis
when defining the routine, or a syntax error occurs. This is also true
when you invoke the routine later. For this reason, we suggest that it
is better to avoid re-using the names of existing SQL functions for
your own stored routines.

The `IGNORE_SPACE' SQL mode applies to built-in functions, not to
stored routines. It is always allowable to have spaces after a routine
name, regardless of whether `IGNORE_SPACE' is enabled.

The parameter list enclosed within parentheses must always be present.
If there are no parameters, an empty parameter list of `()' should be
used.

Each parameter can be declared to use any valid data type, except that
the `COLLATE' attribute cannot be used.

Each parameter is an `IN' parameter by default.  To specify otherwise
for a parameter, use the keyword `OUT' or `INOUT' before the parameter
name.

*Note*:

Specifying a parameter as `IN', `OUT', or `INOUT' is valid only for a
`PROCEDURE'.  (`FUNCTION' parameters are always regarded as `IN'
parameters.)

An `IN' parameter passes a value into a procedure. The procedure might
modify the value, but the modification is not visible to the caller
when the procedure returns. An `OUT' parameter passes a value from the
procedure back to the caller. Its initial value is `NULL' within the
procedure, and its value is visible to the caller when the procedure
returns. An `INOUT' parameter is initialized by the caller, can be
modified by the procedure, and any change made by the procedure is
visible to the caller when the procedure returns.

For each `OUT' or `INOUT' parameter, pass a user-defined variable so
that you can obtain its value when the procedure returns. (For an
example, see *Note call::.) If you are calling the procedure from
within another stored procedure or function, you can also pass a
routine parameter or local routine variable as an `IN' or `INOUT'
parameter.

The `RETURNS' clause may be specified only for a `FUNCTION', for which
it is mandatory. It indicates the return type of the function, and the
function body must contain a `RETURN VALUE' statement. If the `RETURN'
statement returns a value of a different type, the value is coerced to
the proper type. For example, if a function specifies an `ENUM' or
`SET' value in the `RETURNS' clause, but the `RETURN' statement returns
an integer, the value returned from the function is the string for the
corresponding `ENUM' member of set of `SET' members.

The ROUTINE_BODY consists of a valid SQL procedure statement. This can
be a simple statement such as `SELECT' or `INSERT', or it can be a
compound statement written using `BEGIN' and `END'. Compound statement
syntax is described in *Note begin-end::.  Compound statements can
contain declarations, loops, and other control structure statements.
The syntax for these statements is described later in this chapter.
See, for example, *Note declare::, and *Note flow-control-constructs::.

Some statements are not allowed in stored routines; see *Note
routine-restrictions::.

MySQL stores the `sql_mode' system variable setting that is in effect
at the time a routine is created, and always executes the routine with
this setting in force, _regardless of the current server SQL mode_.

The `CREATE FUNCTION' statement was used in earlier versions of MySQL
to support UDFs (user-defined functions). See *Note adding-functions::.
UDFs continue to be supported, even with the existence of stored
functions. A UDF can be regarded as an external stored function.
However, do note that stored functions share their namespace with UDFs.
See *Note function-resolution::, for the rules describing how the
server interprets references to different kinds of functions.

A procedure or function is considered `deterministic' if it always
produces the same result for the same input parameters, and `not
deterministic' otherwise. If neither `DETERMINISTIC' nor `NOT
DETERMINISTIC' is given in the routine definition, the default is `NOT
DETERMINISTIC'.

A routine that contains the `NOW()' function (or its synonyms) or
`RAND()' is non-deterministic, but it might still be replication-safe.
For `NOW()', the binary log includes the timestamp and replicates
correctly.  `RAND()' also replicates correctly as long as it is invoked
only once within a routine. (You can consider the routine execution
timestamp and random number seed as implicit inputs that are identical
on the master and slave.)

In versions prior to 5.1.21-beta, the `DETERMINISTIC' characteristic is
accepted, but not used by the optimizer. However, if binary logging is
enabled, this characteristic always affects which routine definitions
MySQL accepts. See *Note stored-procedure-logging::.

Several characteristics provide information about the nature of data
use by the routine. In MySQL, these characteristics are advisory only.
The server does not use them to constrain what kinds of statements a
routine will be allowed to execute.

   * `CONTAINS SQL' indicates that the routine does not contain
     statements that read or write data. This is the default if none of
     these characteristics is given explicitly. Examples of such
     statements are `SET @x = 1' or `DO RELEASE_LOCK('abc')', which
     execute but neither read nor write data.

   * `NO SQL' indicates that the routine contains no SQL statements.

   * `READS SQL DATA' indicates that the routine contains statements
     that read data (for example, `SELECT'), but not statements that
     write data.

   * `MODIFIES SQL DATA' indicates that the routine contains statements
     that may write data (for example, `INSERT' or `DELETE').

The `SQL SECURITY' characteristic can be used to specify whether the
routine should be executed using the permissions of the user who
creates the routine or the user who invokes it. The default value is
`DEFINER'.  This feature is new in SQL:2003. The creator or invoker must
have permission to access the database with which the routine is
associated. It is necessary to have the `EXECUTE' privilege to be able
to execute the routine. The user that must have this privilege is
either the definer or invoker, depending on how the `SQL SECURITY'
characteristic is set.

The optional `DEFINER' clause specifies the MySQL account to be used
when checking access privileges at routine execution time for routines
that have the `SQL SECURITY DEFINER' characteristic. The `DEFINER'
clause was added in MySQL 5.1.8.

If a USER value is given for the `DEFINER' clause, it should be a MySQL
account in `'USER_NAME'@'HOST_NAME'' format (the same format used in
the `GRANT' statement). The USER_NAME and HOST_NAME values both are
required.  The definer can also be given as `CURRENT_USER' or
`CURRENT_USER()'. The default `DEFINER' value is the user who executes
the `CREATE PROCEDURE' or `CREATE FUNCTION' or statement. (This is the
same as `DEFINER = CURRENT_USER'.)

If you specify the `DEFINER' clause, these rules determine the legal
`DEFINER' user values:

   * If you do not have the `SUPER' privilege, the only legal USER
     value is your own account, either specified literally or by using
     `CURRENT_USER'. You cannot set the definer to some other account.

   * If you have the `SUPER' privilege, you can specify any
     syntactically legal account name. If the account does not actually
     exist, a warning is generated.

     Although it is possible to create routines with a non-existent
     `DEFINER' value, an error occurs if the routine executes with
     definer privileges but the definer does not exist at execution
     time.

When the routine is invoked, an implicit `USE DB_NAME' is performed (and
undone when the routine terminates). `USE' statements within stored
routines are disallowed.

The server uses the data type of a routine parameter or function return
value as follows. These rules also apply to local routine variables
created with the `DECLARE' statement (*Note declare-local-variables::).

   * Assignments are checked for data type mismatches and overflow.
     Conversion and overflow problems result in warnings, or errors in
     strict mode.

   * Only scalar values can be assigned to parameters or variables. For
     example, a statement such as `SET x = (SELECT 1, 2)' is invalid.

   * For character data types, if there is a `CHARACTER SET' clause in
     the declaration, the specified character set and its default
     collation are used. If there is no such clause, the database
     character set and collation that are in effect at the time the
     routine is created are used. (These are given by the values of the
     `character_set_database' and `collation_database' system
     variables.) The `COLLATE' attribute is not supported. (This
     includes use of `BINARY', because in this context `BINARY'
     specifies the binary collation of the character set.)

The `COMMENT' clause is a MySQL extension, and may be used to describe
the stored routine. This information is displayed by the `SHOW CREATE
PROCEDURE' and `SHOW CREATE FUNCTION' statements.

MySQL allows routines to contain DDL statements, such as `CREATE' and
`DROP'. MySQL also allows stored procedures (but not stored functions)
to contain SQL transaction statements such as `COMMIT'. Stored
functions may not contain statements that do explicit or implicit
commit or rollback.  Support for these statements is not required by
the SQL standard, which states that each DBMS vendor may decide whether
to allow them.

Statements that return a result set cannot be used within a stored
function. This includes `SELECT' statements that do not use `INTO' to
fetch column values into variables, `SHOW' statements, and other
statements such as `EXPLAIN'. For statements that can be determined at
function definition time to return a result set, a `Not allowed to
return a result set from a function' error occurs (`ER_SP_NO_RETSET').
For statements that can be determined only at runtime to return a
result set, a `PROCEDURE %s can't return a result set in the given
context' error occurs (`ER_SP_BADSELECT').

The following is an example of a simple stored procedure that uses an
`OUT' parameter. The example uses the `mysql' client `delimiter'
command to change the statement delimiter from `;' to `//' while the
procedure is being defined. This allows the `;' delimiter used in the
procedure body to be passed through to the server rather than being
interpreted by `mysql' itself.

     mysql> delimiter //

     mysql> CREATE PROCEDURE simpleproc (OUT param1 INT)
         -> BEGIN
         ->   SELECT COUNT(*) INTO param1 FROM t;
         -> END;
         -> //
     Query OK, 0 rows affected (0.00 sec)

     mysql> delimiter ;

     mysql> CALL simpleproc(@a);
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT @a;
     +------+
     | @a   |
     +------+
     | 3    |
     +------+
     1 row in set (0.00 sec)

When using the `delimiter' command, you should avoid the use of the
backslash (``\'') character because that is the escape character for
MySQL.

The following is an example of a function that takes a parameter,
performs an operation using an SQL function, and returns the result. In
this case, it is unnecessary to use `delimiter' because the function
definition contains no internal `;' statement delimiters:

     mysql> CREATE FUNCTION hello (s CHAR(20))
     mysql> RETURNS CHAR(50) DETERMINISTIC
         -> RETURN CONCAT('Hello, ',s,'!');
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT hello('world');
     +----------------+
     | hello('world') |
     +----------------+
     | Hello, world!  |
     +----------------+
     1 row in set (0.00 sec)

For information about invoking stored procedures from within programs
written in a language that has a MySQL interface, see *Note call::.


File: manual.info,  Node: alter-procedure,  Next: drop-function,  Prev: create-procedure,  Up: stored-procedure-syntax

23.2.3 `ALTER PROCEDURE' and `ALTER FUNCTION' Syntax
----------------------------------------------------

     ALTER {PROCEDURE | FUNCTION} SP_NAME [CHARACTERISTIC ...]

     CHARACTERISTIC:
         { CONTAINS SQL | NO SQL | READS SQL DATA | MODIFIES SQL DATA }
       | SQL SECURITY { DEFINER | INVOKER }
       | COMMENT 'STRING'

This statement can be used to change the characteristics of a stored
procedure or function. You must have the `ALTER ROUTINE' privilege for
the routine. (That privilege is granted automatically to the routine
creator.) If binary logging is enabled, the `ALTER FUNCTION' statement
might also require the `SUPER' privilege, as described in *Note
stored-procedure-logging::.

More than one change may be specified in an `ALTER PROCEDURE' or `ALTER
FUNCTION' statement.


File: manual.info,  Node: drop-function,  Next: drop-procedure,  Prev: alter-procedure,  Up: stored-procedure-syntax

23.2.4 `DROP FUNCTION' Syntax
-----------------------------

The `DROP FUNCTION' statement is used to drop stored functions and
user-defined functions (UDFs):

   * For information about dropping stored functions, see *Note
     drop-procedure::.

   * For information about dropping user-defined functions, see *Note
     drop-function-udf::.


File: manual.info,  Node: drop-procedure,  Next: call,  Prev: drop-function,  Up: stored-procedure-syntax

23.2.5 `DROP PROCEDURE' and `DROP FUNCTION' Syntax
--------------------------------------------------

     DROP {PROCEDURE | FUNCTION} [IF EXISTS] SP_NAME

This statement is used to drop a stored procedure or function.  That
is, the specified routine is removed from the server. You must have the
`ALTER ROUTINE' privilege for the routine. (That privilege is granted
automatically to the routine creator.)

The `IF EXISTS' clause is a MySQL extension. It prevents an error from
occurring if the procedure or function does not exist. A warning is
produced that can be viewed with `SHOW WARNINGS'.

`DROP FUNCTION' is also used to drop user-defined functions (see *Note
drop-function-udf::).


File: manual.info,  Node: call,  Next: begin-end,  Prev: drop-procedure,  Up: stored-procedure-syntax

23.2.6 `CALL' Statement Syntax
------------------------------

     CALL SP_NAME([PARAMETER[,...]])
     CALL SP_NAME[()]

The `CALL' statement invokes a procedure that was defined previously
with `CREATE PROCEDURE'.

`CALL' can pass back values to its caller using parameters that are
declared as `OUT' or `INOUT' parameters. It also `returns' the number
of rows affected, which a client program can obtain at the SQL level by
calling the `ROW_COUNT()' function and from C by calling the *Note
`mysql_affected_rows()': mysql-affected-rows. C API function.

As of MySQL 5.1.13, stored procedures that take no arguments can be
invoked without parentheses. That is, `CALL p()' and `CALL p' are
equivalent.

To get back a value from a procedure using an `OUT' or `INOUT'
parameter, pass the parameter by means of a user variable, and then
check the value of the variable after the procedure returns. (If you
are calling the procedure from within another stored procedure or
function, you can also pass a routine parameter or local routine
variable as an `IN' or `INOUT' parameter.) For an `INOUT' parameter,
initialize its value before passing it to the procedure. The following
procedure has an `OUT' parameter that the procedure sets to the current
server version, and an `INOUT' value that the procedure increments by
one from its current value:

     CREATE PROCEDURE p (OUT ver_param VARCHAR(25), INOUT incr_param INT)
     BEGIN
       # Set value of OUT parameter
       SELECT VERSION() INTO ver_param;
       # Increment value of INOUT parameter
       SET incr_param = incr_param + 1;
     END;

Before calling the procedure, initialize the variable to be passed as
the `INOUT' parameter. After calling the procedure, the values of the
two variables will have been set or modified:

     mysql> SET @increment = 10;
     mysql> CALL p(@version, @increment);
     mysql> SELECT @version, @increment;
     +-----------------+------------+
     | @version        | @increment |
     +-----------------+------------+
     | 5.1.12-beta-log | 11         |
     +-----------------+------------+

If you write C programs that use the `CALL' SQL statement to execute
stored procedures that produce result sets, you _must_ set the
`CLIENT_MULTI_RESULTS' flag, either explicitly, or implicitly by setting
`CLIENT_MULTI_STATEMENTS' when you call *Note `mysql_real_connect()':
mysql-real-connect. This is because each such stored procedure produces
multiple results: the result sets returned by statements executed
within the procedure, as well as a result to indicate the call status.
To process the result of a `CALL' statement, use a loop that calls
*Note `mysql_next_result()': mysql-next-result. to determine whether
there are more results. For an example, see *Note
c-api-multiple-queries::.

For programs written in a language that provides a MySQL interface,
there is no native method for directly retrieving the results of `OUT'
or `INOUT' parameters from `CALL' statements. To get the parameter
values, pass user-defined variables to the procedure in the `CALL'
statement and then execute a `SELECT' statement to produce a result set
containing the variable values. The following example illustrates the
technique (without error checking) for a stored procedure `p1' that has
two `OUT' parameters.

     mysql_query(mysql, "CALL p1(@param1, @param2)");
     mysql_query(mysql, "SELECT @param1, @param2");
     result = mysql_store_result(mysql);
     row = mysql_fetch_row(result);
     mysql_free_result(result);

After the preceding code executes, `row[0]' and `row[1]' contain the
values of `@param1' and `@param2', respectively.

To handle `INOUT' parameters, execute a statement prior to the `CALL'
that sets the user variables to the values to be passed to the
procedure.


File: manual.info,  Node: begin-end,  Next: declare,  Prev: call,  Up: stored-procedure-syntax

23.2.7 `BEGIN ... END' Compound Statement Syntax
------------------------------------------------

     [BEGIN_LABEL:] BEGIN
         [STATEMENT_LIST]
     END [END_LABEL]

`BEGIN ... END' syntax is used for writing compound statements, which
can appear within stored routines and triggers. A compound statement
can contain multiple statements, enclosed by the `BEGIN' and `END'
keywords.  STATEMENT_LIST represents a list of one or more statements.
Each statement within STATEMENT_LIST must be terminated by a semicolon
(`;') statement delimiter. Note that STATEMENT_LIST is optional, which
means that the empty compound statement (`BEGIN END') is legal.

Use of multiple statements requires that a client is able to send
statement strings containing the `;' statement delimiter. This is
handled in the `mysql' command-line client with the `delimiter'
command. Changing the `;' end-of-statement delimiter (for example, to
`//') allows `;' to be used in a routine body. For an example, see
*Note create-procedure::.

A compound statement can be labeled.  END_LABEL cannot be given unless
BEGIN_LABEL also is present. If both are present, they must be the same.

The optional `[NOT] ATOMIC' clause is not yet supported. This means
that no transactional savepoint is set at the start of the instruction
block and the `BEGIN' clause used in this context has no effect on the
current transaction.


File: manual.info,  Node: declare,  Next: variables-in-stored-procedures,  Prev: begin-end,  Up: stored-procedure-syntax

23.2.8 `DECLARE' Statement Syntax
---------------------------------

The `DECLARE' statement is used to define various items local to a
routine:

   * Local variables. See *Note variables-in-stored-procedures::.

   * Conditions and handlers. See *Note conditions-and-handlers::.

   * Cursors. See *Note cursors::.

The `SIGNAL' and `RESIGNAL' statements are not currently supported.

`DECLARE' is allowed only inside a `BEGIN ... END' compound statement
and must be at its start, before any other statements.

Declarations must follow a certain order. Cursors must be declared
before declaring handlers, and variables and conditions must be
declared before declaring either cursors or handlers.


File: manual.info,  Node: variables-in-stored-procedures,  Next: conditions-and-handlers,  Prev: declare,  Up: stored-procedure-syntax

23.2.9 Variables in Stored Routines
-----------------------------------

* Menu:

* declare-local-variables::      `DECLARE' Local Variables
* set-statement::                Variable `SET' Statement
* select-into-statement::        `SELECT ... INTO' Statement

You may declare and use variables within a routine.


File: manual.info,  Node: declare-local-variables,  Next: set-statement,  Prev: variables-in-stored-procedures,  Up: variables-in-stored-procedures

23.2.9.1 `DECLARE' Local Variables
..................................

     DECLARE VAR_NAME[,...] TYPE [DEFAULT VALUE]

This statement is used to declare local variables. To provide a default
value for the variable, include a `DEFAULT' clause. The value can be
specified as an expression; it need not be a constant. If the `DEFAULT'
clause is missing, the initial value is `NULL'.

Local variables are treated like routine parameters with respect to
data type and overflow checking. See *Note create-procedure::.

The scope of a local variable is within the `BEGIN ...  END' block
where it is declared. The variable can be referred to in blocks nested
within the declaring block, except those blocks that declare a variable
with the same name.


File: manual.info,  Node: set-statement,  Next: select-into-statement,  Prev: declare-local-variables,  Up: variables-in-stored-procedures

23.2.9.2 Variable `SET' Statement
.................................

     SET VAR_NAME = EXPR [, VAR_NAME = EXPR] ...

The `SET' statement in stored routines is an extended version of the
general `SET' statement. Referenced variables may be ones declared
inside a routine, or global system variables.

The `SET' statement in stored routines is implemented as part of the
pre-existing `SET' syntax. This allows an extended syntax of `SET a=x,
b=y, ...' where different variable types (locally declared variables
and global and session server variables) can be mixed. This also allows
combinations of local variables and some options that make sense only
for system variables; in that case, the options are recognized but
ignored.


File: manual.info,  Node: select-into-statement,  Prev: set-statement,  Up: variables-in-stored-procedures

23.2.9.3 `SELECT ... INTO' Statement
....................................

     SELECT COL_NAME[,...] INTO VAR_NAME[,...] TABLE_EXPR

This `SELECT' syntax stores selected columns directly into variables.
Therefore, only a single row may be retrieved.

     SELECT id,data INTO x,y FROM test.t1 LIMIT 1;

User variable names are not case sensitive. See *Note user-variables::.

*Important*:

SQL variable names should not be the same as column names.  If an SQL
statement, such as a `SELECT ...  INTO' statement, contains a reference
to a column and a declared local variable with the same name, MySQL
currently interprets the reference as the name of a variable. For
example, in the following statement, `xname' is interpreted as a
reference to the `xname' _variable_ rather than the `xname' _column_:

     CREATE PROCEDURE sp1 (x VARCHAR(5))
       BEGIN
         DECLARE xname VARCHAR(5) DEFAULT 'bob';
         DECLARE newname VARCHAR(5);
         DECLARE xid INT;

         SELECT xname,id INTO newname,xid
           FROM table1 WHERE xname = xname;
         SELECT newname;
       END;

When this procedure is called, the `newname' variable returns the value
`'bob'' regardless of the value of the `table1.xname' column.

See also *Note routine-restrictions::.


File: manual.info,  Node: conditions-and-handlers,  Next: cursors,  Prev: variables-in-stored-procedures,  Up: stored-procedure-syntax

23.2.10 Conditions and Handlers
-------------------------------

* Menu:

* declare-conditions::           `DECLARE' Conditions
* declare-handlers::             `DECLARE' Handlers

Certain conditions may require specific handling. These conditions can
relate to errors, as well as to general flow control inside a routine.


File: manual.info,  Node: declare-conditions,  Next: declare-handlers,  Prev: conditions-and-handlers,  Up: conditions-and-handlers

23.2.10.1 `DECLARE' Conditions
..............................

     DECLARE CONDITION_NAME CONDITION FOR CONDITION_VALUE

     CONDITION_VALUE:
         SQLSTATE [VALUE] SQLSTATE_VALUE
       | MYSQL_ERROR_CODE

This statement specifies conditions that need specific handling. It
associates a name with a specified error condition. The name can
subsequently be used in a `DECLARE HANDLER' statement. See *Note
declare-handlers::.

A CONDITION_VALUE can be an SQLSTATE value or a MySQL error code. For a
list of SQLSTATE and error values, see *Note error-messages-server::.


File: manual.info,  Node: declare-handlers,  Prev: declare-conditions,  Up: conditions-and-handlers

23.2.10.2 `DECLARE' Handlers
............................

     DECLARE HANDLER_TYPE HANDLER FOR CONDITION_VALUE[,...] STATEMENT

     HANDLER_TYPE:
         CONTINUE
       | EXIT
       | UNDO

     CONDITION_VALUE:
         SQLSTATE [VALUE] SQLSTATE_VALUE
       | CONDITION_NAME
       | SQLWARNING
       | NOT FOUND
       | SQLEXCEPTION
       | MYSQL_ERROR_CODE

The `DECLARE ... HANDLER' statement specifies handlers that each may
deal with one or more conditions. If one of these conditions occurs,
the specified STATEMENT is executed.  STATEMENT can be a simple
statement (for example, `SET VAR_NAME = VALUE'), or it can be a
compound statement written using `BEGIN' and `END' (see *Note
begin-end::).

For a `CONTINUE' handler, execution of the current routine continues
after execution of the handler statement. For an `EXIT' handler,
execution terminates for the `BEGIN ... END' compound statement in
which the handler is declared. (This is true even if the condition
occurs in an inner block.) The `UNDO' handler type statement is not yet
supported.

If a condition occurs for which no handler has been declared, the
default action is `EXIT'.

A CONDITION_VALUE can be any of the following values:

   * An SQLSTATE value or a MySQL error code. You should not use
     SQLSTATE value `'00000'' or error code 0, because those indicate
     sucess rather than an error condition. For a list of SQLSTATE and
     error values, see *Note error-messages-server::.

   * A condition name previously specified with `DECLARE ...
     CONDITION'. See *Note declare-conditions::.

   * `SQLWARNING' is shorthand for all SQLSTATE codes that begin with
     `01'.

   * `NOT FOUND' is shorthand for all SQLSTATE codes that begin with
     `02'. This is relevant only within the context of cursors and is
     used to control what happens when a cursor reaches the end of a
     data set.

   * `SQLEXCEPTION' is shorthand for all SQLSTATE codes not caught by
     `SQLWARNING' or `NOT FOUND'.

Example:

     mysql> CREATE TABLE test.t (s1 int,primary key (s1));
     Query OK, 0 rows affected (0.00 sec)

     mysql> delimiter //

     mysql> CREATE PROCEDURE handlerdemo ()
         -> BEGIN
         ->   DECLARE CONTINUE HANDLER FOR SQLSTATE '23000' SET @x2 = 1;
         ->   SET @x = 1;
         ->   INSERT INTO test.t VALUES (1);
         ->   SET @x = 2;
         ->   INSERT INTO test.t VALUES (1);
         ->   SET @x = 3;
         -> END;
         -> //
     Query OK, 0 rows affected (0.00 sec)

     mysql> CALL handlerdemo()//
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT @x//
         +------+
         | @x   |
         +------+
         | 3    |
         +------+
         1 row in set (0.00 sec)

The example associates a handler with SQLSTATE 23000, which occurs for
a duplicate-key error. Notice that `@x' is `3', which shows that MySQL
executed to the end of the procedure. If the line `DECLARE CONTINUE
HANDLER FOR SQLSTATE '23000' SET @x2 = 1;' had not been present, MySQL
would have taken the default path (`EXIT') after the second `INSERT'
failed due to the `PRIMARY KEY' constraint, and `SELECT @x' would have
returned `2'.

If you want to ignore a condition, you can declare a `CONTINUE' handler
for it and associate it with an empty block. For example:

     DECLARE CONTINUE HANDLER FOR SQLWARNING BEGIN END;

The statement associated with a handler cannot use `ITERATE' or `LEAVE'
to refer to labels for blocks that enclose the handler declaration.
That is, the scope of a block label does not include the code for
handlers declared within the block.  Consider the following example,
where the `REPEAT' block has a label of `retry':

     CREATE PROCEDURE p ()
     BEGIN
       DECLARE i INT DEFAULT 3;
       retry:
         REPEAT
           BEGIN
             DECLARE CONTINUE HANDLER FOR SQLWARNING
               BEGIN
                 ITERATE retry;  # illegal
               END;
           END;
           IF i < 0 THEN
             LEAVE retry;        # legal
           END IF;
           SET i = i - 1;
         UNTIL FALSE END REPEAT;
     END;

The label is in scope for the `IF' statement within the block. It is
not in scope for the `CONTINUE' handler, so the reference there is
invalid and results in an error:

     ERROR 1308 (42000): LEAVE with no matching label: retry

To avoid using references to outer labels in handlers, you can use
different strategies:

   * If you want to leave the block, you can use an `EXIT' handler:

          DECLARE EXIT HANDLER FOR SQLWARNING BEGIN END;

   * If you want to iterate, you can set a status variable in the
     handler that can be checked in the enclosing block to determine
     whether the handler was invoked. The following example uses the
     variable `done' for this purpose:

          CREATE PROCEDURE p ()
          BEGIN
            DECLARE i INT DEFAULT 3;
            DECLARE done INT DEFAULT FALSE;
            retry:
              REPEAT
                BEGIN
                  DECLARE CONTINUE HANDLER FOR SQLWARNING
                    BEGIN
                      SET done = TRUE;
                    END;
                END;
                IF NOT done AND i < 0 THEN
                  LEAVE retry;
                END IF;
                SET i = i - 1;
              UNTIL FALSE END REPEAT;
          END;


File: manual.info,  Node: cursors,  Next: flow-control-constructs,  Prev: conditions-and-handlers,  Up: stored-procedure-syntax

23.2.11 Cursors
---------------

* Menu:

* declare-cursors::              Declaring Cursors
* open::                         Cursor `OPEN' Statement
* fetch::                        Cursor `FETCH' Statement
* close::                        Cursor `CLOSE' Statement

Cursors are supported inside stored procedures and functions and
triggers. The syntax is as in embedded SQL. Cursors currently have
these properties:

   * Asensitive: The server may or may not make a copy of its result
     table

   * Read only: Not updatable

   * Non-scrollable: Can be traversed only in one direction and cannot
     skip rows

Cursors must be declared before declaring handlers. Variables and
conditions must be declared before declaring either cursors or handlers.

Example:

     CREATE PROCEDURE curdemo()
     BEGIN
       DECLARE done INT DEFAULT 0;
       DECLARE a CHAR(16);
       DECLARE b,c INT;
       DECLARE cur1 CURSOR FOR SELECT id,data FROM test.t1;
       DECLARE cur2 CURSOR FOR SELECT i FROM test.t2;
       DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;

       OPEN cur1;
       OPEN cur2;

       REPEAT
         FETCH cur1 INTO a, b;
         FETCH cur2 INTO c;
         IF NOT done THEN
            IF b < c THEN
               INSERT INTO test.t3 VALUES (a,b);
            ELSE
               INSERT INTO test.t3 VALUES (a,c);
            END IF;
         END IF;
       UNTIL done END REPEAT;

       CLOSE cur1;
       CLOSE cur2;
     END


File: manual.info,  Node: declare-cursors,  Next: open,  Prev: cursors,  Up: cursors

23.2.11.1 Declaring Cursors
...........................

     DECLARE CURSOR_NAME CURSOR FOR SELECT_STATEMENT

This statement declares a cursor. Multiple cursors may be declared in a
routine, but each cursor in a given block must have a unique name.

The `SELECT' statement cannot have an `INTO' clause.


File: manual.info,  Node: open,  Next: fetch,  Prev: declare-cursors,  Up: cursors

23.2.11.2 Cursor `OPEN' Statement
.................................

     OPEN CURSOR_NAME

This statement opens a previously declared cursor.


File: manual.info,  Node: fetch,  Next: close,  Prev: open,  Up: cursors

23.2.11.3 Cursor `FETCH' Statement
..................................

     FETCH CURSOR_NAME INTO VAR_NAME [, VAR_NAME] ...

This statement fetches the next row (if a row exists) using the
specified open cursor, and advances the cursor pointer.

If no more rows are available, a No Data condition occurs with SQLSTATE
value 02000. To detect this condition, you can set up a handler for it
(or for a `NOT FOUND' condition). An example is shown in *Note
cursors::.


File: manual.info,  Node: close,  Prev: fetch,  Up: cursors

23.2.11.4 Cursor `CLOSE' Statement
..................................

     CLOSE CURSOR_NAME

This statement closes a previously opened cursor.

If not closed explicitly, a cursor is closed at the end of the compound
statement in which it was declared.


File: manual.info,  Node: flow-control-constructs,  Next: return,  Prev: cursors,  Up: stored-procedure-syntax

23.2.12 Flow Control Constructs
-------------------------------

* Menu:

* if-statement::                 `IF' Statement
* case-statement::               `CASE' Statement
* loop-statement::               `LOOP' Statement
* leave-statement::              `LEAVE' Statement
* iterate-statement::            `ITERATE' Statement
* repeat-statement::             `REPEAT' Statement
* while-statement::              `WHILE' Statement

The `IF', `CASE', `ITERATE', `LEAVE' `LOOP', `WHILE', and `REPEAT'
constructs are fully implemented.

Many of these constructs contain other statements, as indicated by the
grammar specifications in the following sections. Such constructs may
be nested. For example, an `IF' statement might contain a `WHILE' loop,
which itself contains a `CASE' statement.

`FOR' loops are not currently supported.


File: manual.info,  Node: if-statement,  Next: case-statement,  Prev: flow-control-constructs,  Up: flow-control-constructs

23.2.12.1 `IF' Statement
........................

     IF SEARCH_CONDITION THEN STATEMENT_LIST
         [ELSEIF SEARCH_CONDITION THEN STATEMENT_LIST] ...
         [ELSE STATEMENT_LIST]
     END IF

`IF' implements a basic conditional construct. If the SEARCH_CONDITION
evaluates to true, the corresponding SQL statement list is executed. If
no SEARCH_CONDITION matches, the statement list in the `ELSE' clause is
executed. Each STATEMENT_LIST consists of one or more statements.

*Note*:

There is also an `IF()' _function_, which differs from the `IF'
_statement_ described here. See *Note control-flow-functions::.

An `IF ... END IF' block -- like all other flow-control blocks used
within stored routines -- must be terminated with a semicolon, as shown
in this example:

     DELIMITER //

     CREATE FUNCTION SimpleCompare(n INT, m INT)
       RETURNS VARCHAR(20)

       BEGIN
         DECLARE s VARCHAR(20);

         IF n > m THEN SET s = '>';
         ELSEIF n = m THEN SET s = '=';
         ELSE SET s = '<';
         END IF;

         SET s = CONCAT(n, ' ', s, ' ', m);

         RETURN s;
       END //

     DELIMITER ;

As with other flow-control constructs, `IF ... END IF' blocks may be
nested within other flow-control constructs, including other `IF'
statements.  Each `IF' must be terminated by its own `END IF' followed
by a semicolon. You can use indentation to make nested flow-control
blocks more easily readable by humans (although this is not required by
MySQL), as shown here:

     DELIMITER //

     CREATE FUNCTION VerboseCompare (n INT, m INT)
       RETURNS VARCHAR(50)

       BEGIN
         DECLARE s VARCHAR(50);

         IF n = m THEN SET s = 'equals';
         ELSE
           IF n > m THEN SET s = 'greater';
           ELSE SET s = 'less';
           END IF;

           SET s = CONCAT('is ', s, ' than');
         END IF;

         SET s = CONCAT(n, ' ', s, ' ', m, '.');

         RETURN s;
       END //

     DELIMITER ;

In this example, the inner `IF' is evaluated only if `n' is not equal to
`m'.


File: manual.info,  Node: case-statement,  Next: loop-statement,  Prev: if-statement,  Up: flow-control-constructs

23.2.12.2 `CASE' Statement
..........................

     CASE CASE_VALUE
         WHEN WHEN_VALUE THEN STATEMENT_LIST
         [WHEN WHEN_VALUE THEN STATEMENT_LIST] ...
         [ELSE STATEMENT_LIST]
     END CASE

Or:

     CASE
         WHEN SEARCH_CONDITION THEN STATEMENT_LIST
         [WHEN SEARCH_CONDITION THEN STATEMENT_LIST] ...
         [ELSE STATEMENT_LIST]
     END CASE

The `CASE' statement for stored routines implements a complex
conditional construct. If a SEARCH_CONDITION evaluates to true, the
corresponding SQL statement list is executed. If no search condition
matches, the statement list in the `ELSE' clause is executed. Each
STATEMENT_LIST consists of one or more statements.

*Note*:

If no search condition matches the value tested, and the `CASE'
statement contains no `ELSE' clause, a `Case not found for CASE
statement' error results.

Each STATEMENT_LIST consists of one or more statements; an empty
STATEMENT_LIST is not allowed. To handle situations where no value is
matched by any `WHEN' clause, use an `ELSE' containing an empty `BEGIN
... END' block, as shown in this example:

     DELIMITER |

     CREATE PROCEDURE p()
       BEGIN
         DECLARE v INT DEFAULT 1;

         CASE v
           WHEN 2 THEN SELECT v;
           WHEN 3 THEN SELECT 0;
           ELSE
             BEGIN
             END;
         END CASE;
       END;
       |

(The indentation used here in the `ELSE' clause is for purposes of
clarity only, and is not otherwise significant.)

The syntax of the `CASE' _statement_ used inside stored routines
differs slightly from that of the SQL `CASE' _expression_ described in
*Note control-flow-functions::. The `CASE' statement cannot have an
`ELSE NULL' clause, and it is terminated with `END CASE' instead of
`END'.


File: manual.info,  Node: loop-statement,  Next: leave-statement,  Prev: case-statement,  Up: flow-control-constructs

23.2.12.3 `LOOP' Statement
..........................

     [BEGIN_LABEL:] LOOP
         STATEMENT_LIST
     END LOOP [END_LABEL]

`LOOP' implements a simple loop construct, enabling repeated execution
of the statement list, which consists of one or more statements. The
statements within the loop are repeated until the loop is exited;
usually this is accomplished with a `LEAVE' statement.

A `LOOP' statement can be labeled.  END_LABEL cannot be given unless
BEGIN_LABEL also is present. If both are present, they must be the same.


File: manual.info,  Node: leave-statement,  Next: iterate-statement,  Prev: loop-statement,  Up: flow-control-constructs

23.2.12.4 `LEAVE' Statement
...........................

     LEAVE LABEL

This statement is used to exit any labeled flow control construct. It
can be used within `BEGIN ...  END' or loop constructs (`LOOP',
`REPEAT', `WHILE').


File: manual.info,  Node: iterate-statement,  Next: repeat-statement,  Prev: leave-statement,  Up: flow-control-constructs

23.2.12.5 `ITERATE' Statement
.............................

     ITERATE LABEL

`ITERATE' can appear only within `LOOP', `REPEAT', and `WHILE'
statements.  `ITERATE' means `do the loop again.'

Example:

     CREATE PROCEDURE doiterate(p1 INT)
     BEGIN
       label1: LOOP
         SET p1 = p1 + 1;
         IF p1 < 10 THEN ITERATE label1; END IF;
         LEAVE label1;
       END LOOP label1;
       SET @x = p1;
     END


File: manual.info,  Node: repeat-statement,  Next: while-statement,  Prev: iterate-statement,  Up: flow-control-constructs

23.2.12.6 `REPEAT' Statement
............................

     [BEGIN_LABEL:] REPEAT
         STATEMENT_LIST
     UNTIL SEARCH_CONDITION
     END REPEAT [END_LABEL]

The statement list within a `REPEAT' statement is repeated until the
SEARCH_CONDITION is true. Thus, a `REPEAT' always enters the loop at
least once. STATEMENT_LIST consists of one or more statements.

A `REPEAT' statement can be labeled.  END_LABEL cannot be given unless
BEGIN_LABEL also is present. If both are present, they must be the same.

Example:

     mysql> delimiter //

     mysql> CREATE PROCEDURE dorepeat(p1 INT)
         -> BEGIN
         ->   SET @x = 0;
         ->   REPEAT SET @x = @x + 1; UNTIL @x > p1 END REPEAT;
         -> END
         -> //
     Query OK, 0 rows affected (0.00 sec)

     mysql> CALL dorepeat(1000)//
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT @x//
     +------+
     | @x   |
     +------+
     | 1001 |
     +------+
     1 row in set (0.00 sec)


File: manual.info,  Node: while-statement,  Prev: repeat-statement,  Up: flow-control-constructs

23.2.12.7 `WHILE' Statement
...........................

     [BEGIN_LABEL:] WHILE SEARCH_CONDITION DO
         STATEMENT_LIST
     END WHILE [END_LABEL]

The statement list within a `WHILE' statement is repeated as long as the
SEARCH_CONDITION is true.  STATEMENT_LIST consists of one or more
statements.

A `WHILE' statement can be labeled.  END_LABEL cannot be given unless
BEGIN_LABEL also is present. If both are present, they must be the same.

Example:

     CREATE PROCEDURE dowhile()
     BEGIN
       DECLARE v1 INT DEFAULT 5;

       WHILE v1 > 0 DO
         ...
         SET v1 = v1 - 1;
       END WHILE;
     END


File: manual.info,  Node: return,  Prev: flow-control-constructs,  Up: stored-procedure-syntax

23.2.13 `RETURN' Statement Syntax
---------------------------------

     RETURN EXPR

The `RETURN' statement terminates execution of a stored function and
returns the value EXPR to the function caller. There must be at least
one `RETURN' statement in a stored function. There may be more than one
if the function has multiple exit points.

This statement is not used in stored procedures, triggers, or events.


File: manual.info,  Node: stored-procedure-last-insert-id,  Next: stored-procedure-logging,  Prev: stored-procedure-syntax,  Up: stored-procedures

23.3 Stored Procedures, Functions, Triggers, and `LAST_INSERT_ID()'
===================================================================

Within the body of a stored routine (procedure or function) or a
trigger, the value of `LAST_INSERT_ID()' changes the same way as for
statements executed outside the body of these kinds of objects (see
*Note information-functions::). The effect of a stored routine or
trigger upon the value of `LAST_INSERT_ID()' that is seen by following
statements depends on the kind of routine:

   * If a stored procedure executes statements that change the value of
     `LAST_INSERT_ID()', the changed value will be seen by statements
     that follow the procedure call.

   * For stored functions and triggers that change the value, the value
     is restored when the function or trigger ends, so following
     statements will not see a changed value.


File: manual.info,  Node: stored-procedure-logging,  Prev: stored-procedure-last-insert-id,  Up: stored-procedures

23.4 Binary Logging of Stored Routines and Triggers
===================================================

The binary log contains information about SQL statements that modify
database contents. This information is stored in the form of `events'
that describe the modifications. The binary log has two important
purposes:

   * For replication, the binary log is used on master replication
     servers as a record of the statements to be sent to slave servers.
     The master server sends the events contained in its binary log to
     its slaves, which execute those events to make the same data
     changes that were made on the master. See *Note
     replication-implementation::.

   * Certain data recovery operations require use of the binary log.
     After a backup file has been restored, the events in the binary
     log that were recorded after the backup was made are re-executed.
     These events bring databases up to date from the point of the
     backup. See *Note recovery-from-backups::.

However, there are certain binary logging issues that apply with
respect to stored routines (procedures and functions) and triggers, if
logging occurs at the statement level:

   * In some cases, it is possible that a statement will affect
     different sets of rows on a master and a slave.

   * Replicated statements executed on a slave are processed by the
     slave SQL thread, which has full privileges. It is possible for a
     procedure to follow different execution paths on master and slave
     servers, so a user can write a routine containing a dangerous
     statement that will execute only on the slave where it is
     processed by a thread that has full privileges.

   * If a routine that modifies data is non-deterministic, it is not
     repeatable. This can result in different data on a master and
     slave, or cause restored data to differ from the original data.

This section describes how MySQL 5.1 handles binary logging for stored
routines and triggers. It states the current conditions that the
implementation places on the use of stored routines, and what you can
do to avoid problems. It also provides additional information about the
reasons for these conditions.

In general, the issues described here result when binary logging occurs
at the SQL statement level. If you use row-based binary logging, the
log contains changes made to individual rows as a result of executing
SQL statements. When routines or triggers execute, row changes are
logged, not the statements that make the changes. For stored
procedures, this means that the `CALL' statement is not logged. For
stored functions, row changes made within the function are logged, not
the function invocation. For triggers, row changes made by the trigger
are logged. On the slave side, only the row changes are seen, not the
routine or trigger invocation. For general information about row-based
logging, see *Note replication-formats::.

Unless noted otherwise, the remarks here assume that you have enabled
binary logging by starting the server with the `--log-bin' option. (See
*Note binary-log::.) If the binary log is not enabled, replication is
not possible, nor is the binary log available for data recovery.

The current conditions on the use of stored functions in MySQL 5.1 can
be summarized as follows. These conditions do not apply to stored
procedures and they do not apply unless binary logging is enabled.

   * To create or alter a stored function, you must have the `SUPER'
     privilege, in addition to the `CREATE ROUTINE' or `ALTER ROUTINE'
     privilege that is normally required.

   * When you create a stored function, you must declare either that it
     is deterministic or that it does not modify data.  Otherwise, it
     may be unsafe for data recovery or replication.

     By default, for a `CREATE FUNCTION' statement to be accepted, at
     least one of `DETERMINISTIC', `NO SQL', or `READS SQL DATA' must
     be specified explicitly. Otherwise an error occurs:

          ERROR 1418 (HY000): This function has none of DETERMINISTIC, NO SQL,
          or READS SQL DATA in its declaration and binary logging is enabled
          (you *might* want to use the less safe log_bin_trust_function_creators
          variable)

     This function is deterministic (and does not modify data), so it
     is safe:

          CREATE FUNCTION f1(i INT)
          RETURNS INT
          DETERMINISTIC
          READS SQL DATA
          BEGIN
            RETURN i;
          END;

     This function uses `UUID()', which is not deterministic, so the
     function also is not deterministic and is not safe:

          CREATE FUNCTION f2()
          RETURNS CHAR(36) CHARACTER SET utf8
          BEGIN
            RETURN UUID();
          END;

     This function modifies data, so it may not be safe:

          CREATE FUNCTION f3(p_id INT)
          RETURNS INT
          BEGIN
            UPDATE t SET modtime = NOW() WHERE id = p_id;
            RETURN ROW_COUNT();
          END;

     Assessment of the nature of a function is based on the `honesty'
     of the creator: MySQL does not check that a function declared
     `DETERMINISTIC' is free of statements that produce
     non-deterministic results.

   * To relax the preceding conditions on function creation (that you
     must have the `SUPER' privilege and that a function must be
     declared deterministic or to not modify data), set the global
     `log_bin_trust_function_creators' system variable to 1. By
     default, this variable has a value of 0, but you can change it
     like this:

          mysql> SET GLOBAL log_bin_trust_function_creators = 1;

     You can also set this variable by using the
     `--log-bin-trust-function-creators=1' option when starting the
     server.

     If binary logging is not enabled,
     `log_bin_trust_function_creators' does not apply and `SUPER' is
     not required for function creation.

For information about built-in functions that may be unsafe for
replication (and thus cause stored functions that use them to be unsafe
as well), see *Note replication-features::.

Triggers are similar to stored functions, so the preceding remarks
regarding functions also apply to triggers with the following
exception: `CREATE TRIGGER' does not have an optional `DETERMINISTIC'
characteristic, so triggers are assumed to be always deterministic.
However, this assumption might in some cases be invalid. For example,
the `UUID()' function is non-deterministic (and does not replicate).
You should be careful about using such functions in triggers.

Triggers can update tables, so error messages similar to those for
stored functions occur with `CREATE TRIGGER' if you do not have the
required privileges. On the slave side, the slave uses the trigger
`DEFINER' attribute to determine which user is considered to be the
creator of the trigger.

The rest of this section provides additional detail about the logging
implementation and its implications. You need not read it unless you
are interested in the background on the rationale for the current
logging-related conditions on stored routine use. This discussion
applies only for statement-based logging, and not for row-based
logging, with the exception of the first item: `CREATE' and `DROP'
statements are logged as statements regardless of the logging mode.

   * The server writes `CREATE PROCEDURE', `CREATE FUNCTION', `ALTER
     PROCEDURE', `ALTER FUNCTION', `DROP PROCEDURE', and `DROP
     FUNCTION' statements to the binary log.

   * A stored function invocation is logged as a `SELECT' statement if
     the function changes data and occurs within a statement that would
     not otherwise be logged. This prevents non-replication of data
     changes that result from use of stored functions in non-logged
     statements.  For example, `SELECT' statements are not written to
     the binary log, but a `SELECT' might invoke a stored function that
     makes changes. To handle this, a `SELECT FUNC_NAME()' statement is
     written to the binary log when the given function makes a change.
     Suppose that the following statements are executed on the master:

          CREATE FUNCTION f1(a INT) RETURNS INT
          BEGIN
            IF (a < 3) THEN
              INSERT INTO t2 VALUES (a);
            END IF;
            RETURN 0;
          END;

          CREATE TABLE t1 (a INT);
          INSERT INTO t1 VALUES (1),(2),(3);

          SELECT f1(a) FROM t1;

     When the `SELECT' statement executes, the function `f1()' is
     invoked three times. Two of those invocations insert a row, and
     MySQL logs a `SELECT' statement for each of them. That is, MySQL
     writes the following statements to the binary log:

          SELECT f1(1);
          SELECT f1(2);

     The server also logs a `SELECT' statement for a stored function
     invocation when the function invokes a stored procedure that
     causes an error. In this case, the server writes the `SELECT'
     statement to the log along with the expected error code. On the
     slave, if the same error occurs, that is the expected result and
     replication continues. Otherwise, replication stops.

     Note: Before MySQL 5.1.7, you will see these `SELECT FUNC_NAME()'
     statements logged as `DO FUNC_NAME()'. The change to `SELECT' was
     made because use of `DO' was found to yield insufficient control
     over error code checking.

   * Logging stored function invocations rather than the statements
     executed by a function has a security implication for replication,
     which arises from two factors:

        * It is possible for a function to follow different execution
          paths on master and slave servers.

        * Statements executed on a slave are processed by the slave SQL
          thread which has full privileges.

     The implication is that although a user must have the `CREATE
     ROUTINE' privilege to create a function, the user can write a
     function containing a dangerous statement that will execute only
     on the slave where it is processed by a thread that has full
     privileges. For example, if the master and slave servers have
     server ID values of 1 and 2, respectively, a user on the master
     server could create and invoke an unsafe function `unsafe_func()'
     as follows:

          mysql> delimiter //
          mysql> CREATE FUNCTION unsafe_func () RETURNS INT
              -> BEGIN
              ->   IF @@server_id=2 THEN DANGEROUS_STATEMENT; END IF;
              ->   RETURN 1;
              -> END;
              -> //
          mysql> delimiter ;
          mysql> INSERT INTO t VALUES(unsafe_func());

     The `CREATE FUNCTION' and `INSERT' statements are written to the
     binary log, so the slave will execute them. Because the slave SQL
     thread has full privileges, it will execute the dangerous
     statment. Thus, the function invocation has different effects on
     the master and slave and is not replication-safe.

     To guard against this danger for servers that have binary logging
     enabled, stored function creators must have the `SUPER' privilege,
     in addition to the usual `CREATE ROUTINE' privilege that is
     required.  Similarly, to use `ALTER FUNCTION', you must have the
     `SUPER' privilege in addition to the `ALTER ROUTINE' privilege.
     Without the `SUPER' privilege, an error will occur:

          ERROR 1419 (HY000): You do not have the SUPER privilege and
          binary logging is enabled (you *might* want to use the less safe
          log_bin_trust_function_creators variable)

     If you do not want to require function creators to have the
     `SUPER' privilege (for example, if all users with the `CREATE
     ROUTINE' privilege on your system are experienced application
     developers), set the global `log_bin_trust_function_creators'
     system variable to 1. You can also set this variable by using the
     `--log-bin-trust-function-creators=1' option when starting the
     server. If binary logging is not enabled,
     `log_bin_trust_function_creators' does not apply and `SUPER' is
     not required for function creation.

   * If a function that performs updates is non-deterministic, it is
     not repeatable. This can have two undesirable effects:

        * It will make a slave different from the master.

        * Restored data will be different from the original data.

     To deal with these problems, MySQL enforces the following
     requirement: On a master server, creation and alteration of a
     function is refused unless you declare the function to be
     deterministic or to not modify data. Two sets of function
     characteristics apply here:

        * The `DETERMINISTIC' and `NOT DETERMINISTIC' characteristics
          indicate whether a function always produces the same result
          for given inputs.  The default is `NOT DETERMINISTIC' if
          neither characteristic is given. To declare that a function
          is deterministic, you must specify `DETERMINISTIC' explicitly.

        * The `CONTAINS SQL', `NO SQL', `READS SQL DATA', and `MODIFIES
          SQL DATA' characteristics provide information about whether
          the function reads or writes data. Either `NO SQL' or `READS
          SQL DATA' indicates that a function does not change data, but
          you must specify one of these explicitly because the default
          is `CONTAINS SQL' if no characteristic is given.

     By default, for a `CREATE FUNCTION' statement to be accepted, at
     least one of `DETERMINISTIC', `NO SQL', or `READS SQL DATA' must
     be specified explicitly. Otherwise an error occurs:

          ERROR 1418 (HY000): This function has none of DETERMINISTIC, NO SQL,
          or READS SQL DATA in its declaration and binary logging is enabled
          (you *might* want to use the less safe log_bin_trust_function_creators
          variable)

     If you set `log_bin_trust_function_creators' to 1, the requirement
     that functions be deterministic or not modify data is dropped.

   * Stored procedure calls are logged at the statement level rather
     than at the `CALL' level. That is, the server does not log the
     `CALL' statement, it logs those statements within the procedure
     that actually execute. As a result, the same changes that occur on
     the master will be observed on slave servers. This prevents
     problems that could result from a procedure having different
     execution paths on different machines.

     In general, statements executed within a stored procedure are
     written to the binary log using the same rules that would apply
     were the statements to be executed in standalone fashion. Some
     special care is taken when logging procedure statements because
     statement execution within procedures is not quite the same as in
     non-procedure context:

        * A statement to be logged might contain references to local
          procedure variables. These variables do not exist outside of
          stored procedure context, so a statement that refers to such
          a variable cannot be logged literally. Instead, each
          reference to a local variable is replaced by this construct
          for logging purposes:

               NAME_CONST(VAR_NAME, VAR_VALUE)

          VAR_NAME is the local variable name, and VAR_VALUE is a
          constant indicating the value that the variable has at the
          time the statement is logged.  `NAME_CONST()' has a value of
          VAR_VALUE, and a `name' of VAR_NAME. Thus, if you invoke this
          function directly, you get a result like this:

               mysql> SELECT NAME_CONST('myname', 14);
               +--------+
               | myname |
               +--------+
               |     14 |
               +--------+

          `NAME_CONST()' allows a logged standalone statement to be
          executed on a slave with the same effect as the original
          statement that was executed on the master within a stored
          procedure.

        * A statement to be logged might contain references to
          user-defined variables. To handle this, MySQL writes a `SET'
          statement to the binary log to make sure that the variable
          exists on the slave with the same value as on the master. For
          example, if a statement refers to a variable `@my_var', that
          statement will be preceded in the binary log by the following
          statement, where VALUE is the value of `@my_var' on the
          master:

               SET @my_var = VALUE;

        * Procedure calls can occur within a committed or rolled-back
          transaction. Transactional context is accounted for so that
          the transactional aspects of procedure execution are
          replicated correctly. That is, the server logs those
          statements within the procedure that actually execute and
          modify data, and also logs `BEGIN', `COMMIT', and `ROLLBACK'
          statements as necessary. For example, if a procedure updates
          only transactional tables and is executed within a
          transaction that is rolled back, those updates are not
          logged. If the procedure occurs within a committed
          transaction, `BEGIN' and `COMMIT' statements are logged with
          the updates. For a procedure that executes within a
          rolled-back transaction, its statements are logged using the
          same rules that would apply if the statements were executed
          in standalone fashion:

             * Updates to transactional tables are not logged.

             * Updates to non-transactional tables are logged because
               rollback does not cancel them.

             * Updates to a mix of transactional and non-transactional
               tables are logged surrounded by `BEGIN' and `ROLLBACK'
               so that slaves will make the same changes and rollbacks
               as on the master.

   * A stored procedure call is _not_ written to the binary log at the
     statement level if the procedure is invoked from within a stored
     function. In that case, the only thing logged is the statement
     that invokes the function (if it occurs within a statement that is
     logged) or a `DO' statement (if it occurs within a statement that
     is not logged). For this reason, care should be exercised in the
     use of stored functions that invoke a procedure, even if the
     procedure is otherwise safe in itself.


File: manual.info,  Node: triggers,  Next: events,  Prev: stored-procedures,  Up: Top

24 Triggers
***********

* Menu:

* create-trigger::               `CREATE TRIGGER' Syntax
* drop-trigger::                 `DROP TRIGGER' Syntax
* using-triggers::               Using Triggers

A trigger is a named database object that is associated with a table
and that is activated when a particular event occurs for the table.
For example, the following statements create a table and an `INSERT'
trigger. The trigger sums the values inserted into one of the table's
columns:

     mysql> CREATE TABLE account (acct_num INT, amount DECIMAL(10,2));
     Query OK, 0 rows affected (0.03 sec)

     mysql> CREATE TRIGGER ins_sum BEFORE INSERT ON account
         -> FOR EACH ROW SET @sum = @sum + NEW.amount;
     Query OK, 0 rows affected (0.06 sec)

*Important*:

MySQL triggers are activated by SQL statements _only_. They are not
activated by changes in tables made by APIs that do not transmit SQL
statements to the MySQL Server; in particular, they are not activated
by updates made using the `NDB' API.

This chapter describes the syntax for creating and dropping triggers,
and shows some examples of how to use them. Discussion of restrictions
on use of triggers is given in *Note routine-restrictions::. Remarks
regarding binary logging as it applies to triggers are given in *Note
stored-procedure-logging::.

For answers to some common questions about triggers in MySQL 5.1, see
*Note faqs-triggers::.


File: manual.info,  Node: create-trigger,  Next: drop-trigger,  Prev: triggers,  Up: triggers

24.1 `CREATE TRIGGER' Syntax
============================

     CREATE
         [DEFINER = { USER | CURRENT_USER }]
         TRIGGER TRIGGER_NAME TRIGGER_TIME TRIGGER_EVENT
         ON TBL_NAME FOR EACH ROW TRIGGER_STMT

This statement creates a new trigger. A trigger is a named database
object that is associated with a table, and that activates when a
particular event occurs for the table. The trigger becomes associated
with the table named TBL_NAME, which must refer to a permanent table.
You cannot associate a trigger with a `TEMPORARY' table or a view.

MySQL Enterprise

For expert advice on creating triggers subscribe to the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

`CREATE TRIGGER' requires the `TRIGGER' privilege for the table
associated with the trigger. (Before MySQL 5.1.6, this statement
requires the `SUPER' privilege.)

The `DEFINER' clause determines the security context to be used when
checking access privileges at trigger activation time.

TRIGGER_TIME is the trigger action time. It can be `BEFORE' or `AFTER'
to indicate that the trigger activates before or after each row to be
modified.

TRIGGER_EVENT indicates the kind of statement that activates the
trigger. The TRIGGER_EVENT can be one of the following:

   * `INSERT': The trigger is activated whenever a new row is inserted
     into the table; for example, through `INSERT', `LOAD DATA', and
     `REPLACE' statements.

   * `UPDATE': The trigger is activated whenever a row is modified; for
     example, through `UPDATE' statements.

   * `DELETE': The trigger is activated whenever a row is deleted from
     the table; for example, through `DELETE' and `REPLACE' statements.
     However, `DROP TABLE' and `TRUNCATE' statements on the table do
     _not_ activate this trigger, because they do not use `DELETE'.
     Dropping a partition does not activate `DELETE' triggers, either.
     See *Note truncate::.

It is important to understand that the TRIGGER_EVENT does not represent
a literal type of SQL statement that activates the trigger so much as
it represents a type of table operation. For example, an `INSERT'
trigger is activated by not only `INSERT' statements but also `LOAD
DATA' statements because both statements insert rows into a table.

A potentially confusing example of this is the `INSERT INTO ... ON
DUPLICATE KEY UPDATE ...' syntax: a `BEFORE INSERT' trigger will
activate for every row, followed by either an `AFTER INSERT' trigger or
both the `BEFORE UPDATE' and `AFTER UPDATE' triggers, depending on
whether there was a duplicate key for the row.

There cannot be two triggers for a given table that have the same
trigger action time and event. For example, you cannot have two `BEFORE
UPDATE' triggers for a table. But you can have a `BEFORE UPDATE' and a
`BEFORE INSERT' trigger, or a `BEFORE UPDATE' and an `AFTER UPDATE'
trigger.

TRIGGER_STMT is the statement to execute when the trigger activates. If
you want to execute multiple statements, use the `BEGIN ... END'
compound statement construct. This also enables you to use the same
statements that are allowable within stored routines. See *Note
begin-end::. Some statements are not allowed in triggers; see *Note
routine-restrictions::.

MySQL stores the `sql_mode' system variable setting that is in effect
at the time a trigger is created, and always executes the trigger with
this setting in force, _regardless of the current server SQL mode_.

*Note*:

Currently, triggers are not activated by cascaded foreign key actions.
This limitation will be lifted as soon as possible.

In MySQL 5.1, you can write triggers containing direct references to
tables by name, such as the trigger named `testref' shown in this
example:

     CREATE TABLE test1(a1 INT);
     CREATE TABLE test2(a2 INT);
     CREATE TABLE test3(a3 INT NOT NULL AUTO_INCREMENT PRIMARY KEY);
     CREATE TABLE test4(
       a4 INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
       b4 INT DEFAULT 0
     );

     DELIMITER |

     CREATE TRIGGER testref BEFORE INSERT ON test1
       FOR EACH ROW BEGIN
         INSERT INTO test2 SET a2 = NEW.a1;
         DELETE FROM test3 WHERE a3 = NEW.a1;
         UPDATE test4 SET b4 = b4 + 1 WHERE a4 = NEW.a1;
       END;
     |

     DELIMITER ;

     INSERT INTO test3 (a3) VALUES
       (NULL), (NULL), (NULL), (NULL), (NULL),
       (NULL), (NULL), (NULL), (NULL), (NULL);

     INSERT INTO test4 (a4) VALUES
       (0), (0), (0), (0), (0), (0), (0), (0), (0), (0);

Suppose that you insert the following values into table `test1' as
shown here:

     mysql> INSERT INTO test1 VALUES
         -> (1), (3), (1), (7), (1), (8), (4), (4);
     Query OK, 8 rows affected (0.01 sec)
     Records: 8  Duplicates: 0  Warnings: 0

As a result, the data in the four tables will be as follows:

     mysql> SELECT * FROM test1;
     +------+
     | a1   |
     +------+
     |    1 |
     |    3 |
     |    1 |
     |    7 |
     |    1 |
     |    8 |
     |    4 |
     |    4 |
     +------+
     8 rows in set (0.00 sec)

     mysql> SELECT * FROM test2;
     +------+
     | a2   |
     +------+
     |    1 |
     |    3 |
     |    1 |
     |    7 |
     |    1 |
     |    8 |
     |    4 |
     |    4 |
     +------+
     8 rows in set (0.00 sec)

     mysql> SELECT * FROM test3;
     +----+
     | a3 |
     +----+
     |  2 |
     |  5 |
     |  6 |
     |  9 |
     | 10 |
     +----+
     5 rows in set (0.00 sec)

     mysql> SELECT * FROM test4;
     +----+------+
     | a4 | b4   |
     +----+------+
     |  1 |    3 |
     |  2 |    0 |
     |  3 |    1 |
     |  4 |    2 |
     |  5 |    0 |
     |  6 |    0 |
     |  7 |    1 |
     |  8 |    1 |
     |  9 |    0 |
     | 10 |    0 |
     +----+------+
     10 rows in set (0.00 sec)

You can refer to columns in the subject table (the table associated
with the trigger) by using the aliases `OLD' and `NEW'.  `OLD.COL_NAME'
refers to a column of an existing row before it is updated or deleted.
`NEW.COL_NAME' refers to the column of a new row to be inserted or an
existing row after it is updated.

The `DEFINER' clause specifies the MySQL account to be used when
checking access privileges at trigger activation time. If a USER value
is given, it should be a MySQL account in `'USER_NAME'@'HOST_NAME''
format (the same format used in the `GRANT' statement). The USER_NAME
and HOST_NAME values both are required. The definer can also be given as
`CURRENT_USER' or `CURRENT_USER()'. The default `DEFINER' value is the
user who executes the `CREATE TRIGGER' statement. (This is the same as
`DEFINER = CURRENT_USER'.)

If you specify the `DEFINER' clause, these rules determine the legal
`DEFINER' user values:

   * If you do not have the `SUPER' privilege, the only legal USER
     value is your own account, either specified literally or by using
     `CURRENT_USER'. You cannot set the definer to some other account.

   * If you have the `SUPER' privilege, you can specify any
     syntactically legal account name. If the account does not actually
     exist, a warning is generated.

     Although it is possible to create triggers with a non-existent
     `DEFINER' value, it is not a good idea for such triggers to be
     activated until the definer actually does exist. Otherwise, the
     behavior with respect to privilege checking is undefined.

Note: Prior to MySQL 5.1.6, MySQL requires the `SUPER' privilege for
the use of `CREATE TRIGGER', so only the second of the preceding rules
applies. As of 5.1.6, `CREATE TRIGGER' requires the `TRIGGER' privilege
and `SUPER' is required only to be able to set `DEFINER' to a value
other than your own account.

MySQL checks trigger privileges like this:

   * At `CREATE TRIGGER' time, the user that issues the statement must
     have the `TRIGGER' privilege. (`SUPER' prior to MySQL 5.1.6.)

   * At trigger activation time, privileges are checked against the
     `DEFINER' user. This user must have these privileges:

        * The `TRIGGER' privilege.  (`SUPER' prior to MySQL 5.1.6.)

        * The `SELECT' privilege for the subject table if references to
          table columns occur via `OLD.COL_NAME' or `NEW.COL_NAME' in
          the trigger definition.

        * The `UPDATE' privilege for the subject table if table columns
          are targets of `SET NEW.COL_NAME = VALUE' assignments in the
          trigger definition.

        * Whatever other privileges normally are required for the
          statements executed by the trigger.


File: manual.info,  Node: drop-trigger,  Next: using-triggers,  Prev: create-trigger,  Up: triggers

24.2 `DROP TRIGGER' Syntax
==========================

     DROP TRIGGER [IF EXISTS] [SCHEMA_NAME.]TRIGGER_NAME

This statement drops a trigger. The schema (database) name is optional.
If the schema is omitted, the trigger is dropped from the default
schema. `DROP TRIGGER' was added in MySQL 5.0.2. Its use requires the
`TRIGGER' privilege for the table associated with the trigger. (This
statement requires the `SUPER' privilege prior to MySQL 5.1.6.)

Use `IF EXISTS' to prevent an error from occurring for a trigger that
does not exist. A `NOTE' is generated for a non-existent trigger when
using `IF EXISTS'. See *Note show-warnings::. The `IF EXISTS' clause
was added in MySQL 5.1.14.

Triggers for a table are also dropped if you drop the table.

*Note*:

When upgrading from a version of MySQL older than MySQL 5.0.10 to
5.0.10 or newer -- including all MySQL 5.1 releases -- you must drop
all triggers _before upgrading_ and re-create them afterward, or else
`DROP TRIGGER' does not work after the upgrade.  See *Note
upgrading-from-5-0::, for a suggested upgrade procedure.


File: manual.info,  Node: using-triggers,  Prev: drop-trigger,  Up: triggers

24.3 Using Triggers
===================

This section discusses how to use triggers in MySQL 5.1 and some
limitations regarding their use.  Additional information about trigger
limitations is given in *Note routine-restrictions::.

A trigger is a named database object that is associated with a table,
and that activates when a particular event occurs for the table. Some
uses for triggers are to perform checks of values to be inserted into a
table or to perform calculations on values involved in an update.

A trigger is associated with a table and is defined to activate when an
`INSERT', `DELETE', or `UPDATE' statement for the table executes. A
trigger can be set to activate either before or after the triggering
statement. For example, you can have a trigger activate before each row
that is deleted from a table or after each row that is updated.

*Important*:

MySQL triggers are activated by SQL statements _only_. They are not
activated by changes in tables made by APIs that do not transmit SQL
statements to the MySQL Server; in particular, they are not activated
by updates made using the `NDB' API.

To create a trigger or drop a trigger, use the `CREATE TRIGGER' or
`DROP TRIGGER' statement.  The syntax for these statements is described
in *Note create-trigger::, and *Note drop-trigger::.

Here is a simple example that associates a trigger with a table for
`INSERT' statements. It acts as an accumulator to sum the values
inserted into one of the columns of the table.

The following statements create a table and a trigger for it:

     mysql> CREATE TABLE account (acct_num INT, amount DECIMAL(10,2));
     mysql> CREATE TRIGGER ins_sum BEFORE INSERT ON account
         -> FOR EACH ROW SET @sum = @sum + NEW.amount;

The `CREATE TRIGGER' statement creates a trigger named `ins_sum' that
is associated with the `account' table. It also includes clauses that
specify the trigger activation time, the triggering event, and what to
do with the trigger activates:

   * The keyword `BEFORE' indicates the trigger action time. In this
     case, the trigger should activate before each row inserted into
     the table. The other allowable keyword here is `AFTER'.

   * The keyword `INSERT' indicates the event that activates the
     trigger. In the example, `INSERT' statements cause trigger
     activation.  You can also create triggers for `DELETE' and
     `UPDATE' statements.

   * The statement following `FOR EACH ROW' defines the statement to
     execute each time the trigger activates, which occurs once for
     each row affected by the triggering statement In the example, the
     triggered statement is a simple `SET' that accumulates the values
     inserted into the `amount' column. The statement refers to the
     column as `NEW.amount' which means `the value of the `amount'
     column to be inserted into the new row.'

To use the trigger, set the accumulator variable to zero, execute an
`INSERT' statement, and then see what value the variable has afterward:

     mysql> SET @sum = 0;
     mysql> INSERT INTO account VALUES(137,14.98),(141,1937.50),(97,-100.00);
     mysql> SELECT @sum AS 'Total amount inserted';
     +-----------------------+
     | Total amount inserted |
     +-----------------------+
     | 1852.48               |
     +-----------------------+

In this case, the value of `@sum' after the `INSERT' statement has
executed is `14.98 + 1937.50 - 100', or `1852.48'.

To destroy the trigger, use a `DROP TRIGGER' statement. You must
specify the schema name if the trigger is not in the default schema:

     mysql> DROP TRIGGER test.ins_sum;

Triggers for a table are also dropped if you drop the table.

Trigger names exist in the schema namespace, meaning that all triggers
must have unique names within a schema. Triggers in different schemas
can have the same name.

In addition to the requirement that trigger names be unique for a
schema, there are other limitations on the types of triggers you can
create. In particular, you cannot have two triggers for a table that
have the same activation time and activation event. For example, you
cannot define two `BEFORE INSERT' triggers or two `AFTER UPDATE'
triggers for a table. This should rarely be a significant limitation,
because it is possible to define a trigger that executes multiple
statements by using the `BEGIN ... END' compound statement construct
after `FOR EACH ROW'. (An example appears later in this section.)

The `OLD' and `NEW' keywords enable you to access columns in the rows
affected by a trigger.  (`OLD' and `NEW' are not case sensitive.) In an
`INSERT' trigger, only `NEW.COL_NAME' can be used; there is no old row.
In a `DELETE' trigger, only `OLD.COL_NAME' can be used; there is no new
row. In an `UPDATE' trigger, you can use `OLD.COL_NAME' to refer to the
columns of a row before it is updated and `NEW.COL_NAME' to refer to
the columns of the row after it is updated.

A column named with `OLD' is read only. You can refer to it (if you
have the `SELECT' privilege), but not modify it. A column named with
`NEW' can be referred to if you have the `SELECT' privilege for it. In
a `BEFORE' trigger, you can also change its value with `SET
NEW.COL_NAME = VALUE' if you have the `UPDATE' privilege for it. This
means you can use a trigger to modify the values to be inserted into a
new row or that are used to update a row.

In a `BEFORE' trigger, the `NEW' value for an `AUTO_INCREMENT' column
is 0, not the automatically generated sequence number that will be
generated when the new record actually is inserted.

`OLD' and `NEW' are MySQL extensions to triggers.

By using the `BEGIN ... END' construct, you can define a trigger that
executes multiple statements. Within the `BEGIN' block, you also can
use other syntax that is allowed within stored routines such as
conditionals and loops.  However, just as for stored routines, if you
use the `mysql' program to define a trigger that executes multiple
statements, it is necessary to redefine the `mysql' statement delimiter
so that you can use the `;' statement delimiter within the trigger
definition. The following example illustrates these points. It defines
an `UPDATE' trigger that checks the new value to be used for updating
each row, and modifies the value to be within the range from 0 to 100.
This must be a `BEFORE' trigger because the value needs to be checked
before it is used to update the row:

     mysql> delimiter //
     mysql> CREATE TRIGGER upd_check BEFORE UPDATE ON account
         -> FOR EACH ROW
         -> BEGIN
         ->     IF NEW.amount < 0 THEN
         ->         SET NEW.amount = 0;
         ->     ELSEIF NEW.amount > 100 THEN
         ->         SET NEW.amount = 100;
         ->     END IF;
         -> END;//
     mysql> delimiter ;

It can be easier to define a stored procedure separately and then
invoke it from the trigger using a simple `CALL' statement. This is
also advantageous if you want to invoke the same routine from within
several triggers.

There are some limitations on what can appear in statements that a
trigger executes when activated:

   * The trigger cannot use the `CALL' statement to invoke stored
     procedures that return data to the client or that use dynamic SQL.
     (Stored procedures are allowed to return data to the trigger
     through `OUT' or `INOUT' parameters.)

   * The trigger cannot use statements that explicitly or implicitly
     begin or end a transaction such as `START TRANSACTION', `COMMIT',
     or `ROLLBACK'.

MySQL handles errors during trigger execution as follows:

   * If a `BEFORE' trigger fails, the operation on the corresponding
     row is not performed.

   * A `BEFORE' trigger is activated by the _attempt_ to insert or
     modify the row, regardless of whether the attempt subsequently
     succeeds.

   * An `AFTER' trigger is executed only if the `BEFORE' trigger (if
     any) and the row operation both execute successfully.

   * An error during either a `BEFORE' or `AFTER' trigger results in
     failure of the entire statement that caused trigger invocation.

   * For transactional tables, failure of a statement should cause
     rollback of all changes performed by the statement. Failure of a
     trigger causes the statement to fail, so trigger failure also
     causes rollback. For non-transactional tables, such rollback
     cannot be done, so although the statement fails, any changes
     performed prior to the point of the error remain in effect.


File: manual.info,  Node: events,  Next: views,  Prev: triggers,  Up: Top

25 Event Scheduler
******************

* Menu:

* events-overview::              Event Scheduler Overview
* events-syntax::                Event Scheduler Syntax
* events-metadata::              Event Metadata
* events-status-info::           Event Scheduler Status
* events-privileges::            The Event Scheduler and MySQL Privileges
* events-limitations-restrictions::  Event Scheduler Limitations and Restrictions

This chapter describes the _MySQL Event Scheduler_, for which support
was added in MySQL 5.1.6, and is divided into the following sections:

   * *Note events-overview::, provides an introduction to and
     conceptual overview of MySQL Events.

   * *Note events-syntax::, discusses the SQL statements introduced in
     MySQL 5.1.6 for creating, altering, and dropping MySQL Events.

   * *Note events-metadata::, shows how to obtain information about
     events and how this information is stored by the MySQL Server.

   * *Note events-privileges::, discusses the privileges required to
     work with events and the ramifications that events have with
     regard to privileges when executing.

   * *Note events-limitations-restrictions::, describes the
     restrictions and limitations on the use of events.

Additional Resources

You may find the MySQL Event Scheduler User Forum
(http://forums.mysql.com/list.php?119) of use when working with
scheduled events. Here you can discuss the MySQL Event Scheduler with
other MySQL users and the MySQL developers.


File: manual.info,  Node: events-overview,  Next: events-syntax,  Prev: events,  Up: events

25.1 Event Scheduler Overview
=============================

MySQL Events are tasks that run according to a schedule.  Therefore, we
sometimes refer to them as _scheduled_ events. When you create an event,
you are creating a named database object containing one or more SQL
statements to be executed at one or more regular intervals, beginning
and ending at a specific date and time. Conceptually, this is similar
to the idea of the Unix `crontab' (also known as a `cron job') or the
Windows Task Scheduler.

Scheduled tasks of this type are also sometimes known as `temporal
triggers', implying that these are objects that are triggered by the
passage of time. While this is essentially correct, we prefer to use
the term _events_ in order to avoid confusion with triggers of the type
discussed in *Note triggers::.  Events should more specifically not be
confused with `temporary triggers'. Whereas a trigger is a database
object whose statements are executed in response to a specific type of
event that occurs on a given table, a (scheduled) event is an object
whose statements are executed in response to the passage of a specified
time interval.

While there is no provision in the SQL Standard for event scheduling,
there are precedents in other database systems, and you may notice some
similarities between these implementations and that found in the MySQL
Server.

MySQL Events have the following major features and properties:

   * In MySQL 5.1.12 and later, an event is uniquely identified by its
     name and the schema to which it is assigned. (Previously, an event
     was also unique to its definer.)

   * An event performs a specific action according to a schedule.  This
     action consists of an SQL statement, which can be a compound
     statement in a `BEGIN ... END' block if desired (see *Note
     begin-end::). An event's timing can be either _one-time_ or
     _recurrent_. A one-time event executes one time only. A recurrent
     event repeats its action at a regular interval, and the schedule
     for a recurring event can be assigned a specific start day and
     time, end day and time, both, or neither. (By default, a recurring
     event's schedule begins as soon as it is created, and continues
     indefinitely, until it is disabled or dropped.)

   * Users can create, modify, and drop scheduled events using SQL
     statements intended for these purposes. Syntactically invalid
     event creation and modification statements fail with an
     appropriate error message. _A user may include statements in an
     event's action which require privileges that the user does not
     actually have_. The event creation or modification statement
     succeeds but the event's action fails. See *Note
     events-privileges:: for details.

   * Many of the properties of an event can be set or modified using
     SQL statements. These properties include the event's name, timing,
     persistence (that is, whether it is preserved following the
     expiration of its schedule), status (enabled or disabled), action
     to be performed, and the schema to which it is assigned. See *Note
     alter-event::.

     The default definer of an event is the user who created the event,
     unless the event has been altered, in which case the definer is
     the user who issued the last `ALTER EVENT' statement affecting
     that event. An event can be modified by any user having the `EVENT'
     privilege on the database for which the event is defined.  (Prior
     to MySQL 5.1.12, only an event's definer, or a user having
     privileges on the `mysql.event' table, could modify a given
     event.) See *Note events-privileges::.

   * An event's action statement may include most SQL statements
     permitted within stored routines.

Events are executed by a special _event scheduler thread_; when we
refer to the Event Scheduler, we actually refer to this thread. When
running, the event scheduler thread and its current state can be seen
by users having the `PROCESS' privilege in the output of `SHOW
PROCESSLIST', as shown in the discussion that follows.

The global `event_scheduler' system variable determines whether the
Event Scheduler is enabled and running on the server. Beginning with
MySQL 5.1.12, it has one of these 3 values, which affect event
scheduling as described here:

   * `OFF': The Event Scheduler is stopped. The event scheduler thread
     does not run, is not shown in the output of `SHOW PROCESSLIST',
     and no scheduled events are executed. `OFF' is the default value
     for `event_scheduler'.

     When the Event Scheduler is stopped (`event_scheduler' is `OFF'),
     it can be started by setting the value of `event_scheduler' to
     `ON'. (See next item.)

   * `ON': The Event Scheduler is started; the event scheduler thread
     runs and executes all scheduled events.

     When the Event Scheduler is `ON', the event scheduler thread is
     listed in the output of `SHOW PROCESSLIST' as a daemon process,
     and its state is represented as shown here:

          mysql> SHOW PROCESSLIST\G
          *************************** 1. row ***************************
               Id: 1
             User: root
             Host: localhost
               db: NULL
          Command: Query
             Time: 0
            State: NULL
             Info: show processlist
          *************************** 2. row ***************************
               Id: 2
             User: event_scheduler
             Host: localhost
               db: NULL
          Command: Daemon
             Time: 3
            State: Waiting for next activation
             Info: NULL
          2 rows in set (0.00 sec)

     Event scheduling can be stopped by setting the value of
     `event_scheduler' to `OFF'.

   * `DISABLED': This value renders the Event Scheduler
     non-operational. When the Event Scheduler is `DISABLED', the event
     scheduler thread does not run (and so does not appear in the
     output of `SHOW PROCESSLIST'). In addition, the Event Scheduler
     state cannot be changed at runtime.

If the Event Scheduler status has not been set to `DISABLED',
`event_scheduler' can be toggled between `ON' and `OFF' (using `SET').
It is also possible to use `0' for `OFF', and `1' for `ON' when setting
this variable. Thus, any of the following 4 statements can be used in
the `mysql' client to turn on the Event Scheduler:

     SET GLOBAL event_scheduler = ON;
     SET @@global.event_scheduler = ON;
     SET GLOBAL event_scheduler = 1;
     SET @@global.event_scheduler = 1;

Similarly, any of these 4 statements can be used to turn off the Event
Scheduler:

     SET GLOBAL event_scheduler = OFF;
     SET @@global.event_scheduler = OFF;
     SET GLOBAL event_scheduler = 0;
     SET @@global.event_scheduler = 0;

Although `ON' and `OFF' have numeric equivalents, the value displayed
for `event_scheduler' by `SELECT' or `SHOW VARIABLES' is always one of
`OFF', `ON', or `DISABLED'. _`DISABLED' has no numeric equivalent_. For
this reason, `ON' and `OFF' are usually preferred over `1' and `0' when
setting this variable.

Note that attempting to set `event_scheduler' without specifying it as
a global variable causes an error:

     mysql< SET @@event_scheduler = OFF;
     `ERROR 1229 (HY000): Variable 'event_scheduler' is a GLOBAL
     variable and should be set with SET GLOBAL'

*Important*:

It is possible to set the Event Scheduler to `DISABLED' only at server
startup. If `event_scheduler' is `ON' or `OFF', you cannot set it to
`DISABLED' at runtime. Also, if the Event Scheduler is set to
`DISABLED' at startup, you cannot change the value of `event_scheduler'
at runtime.

To disable the event scheduler, use one of the following two methods:

   * As a command-line option when starting the server:

          --event-scheduler=DISABLED

   * In the server configuration file (`my.cnf', or `my.ini' on Windows
     systems), include the line where it will be read by the server
     (for example, in a `[mysqld]' section):

          event_scheduler=DISABLED

To enable the Event Scheduler, restart the server without the
`--event-scheduler=DISABLED' command-line option, or after removing or
commenting out the line containing `event_scheduler=DISABLED' in the
server configuration file, as appropriate. Alternatively, you can use
`ON' (or `1') or `OFF' (or `0') in place of the `DISABLED' value when
starting the server.

*Note*:

You can issue event-manipulation statements when `event_scheduler' is
set to `DISABLED'. No warnings or errors are generated in such cases
(provided that the statements are themselves valid). However, scheduled
events cannot execute until this variable is set to `ON' (or `1'). Once
this has been done, the event scheduler thread executes all events
whose scheduling conditions are satisfied.

In MySQL 5.1.11, `event_scheduler' behaved as follows: this variable
could take one of the values `0' (or `OFF'), `1' (or `ON'), or `2'.
Setting it to `0' turned event scheduling off, so that the event
scheduler thread did not run; the `event_scheduler' variable could not
be set to this value while the server was running. Setting it to `1' so
that the event scheduler thread ran and executed scheduled events. In
this state, the event scheduler thread appeared to be sleeping when
viewed with `SHOW PROCESSLIST'. When `event_scheduler' was set to `2'
(which was the default value), the Event Scheduler was considered to be
`suspended'; the event scheduler thread ran and could be seen in the
output of `SHOW PROCESSLIST' (where `Suspended' was displayed in the
`State' column), but did not execute any scheduled events. The value of
`event_scheduler' could be changed only between `1' (or `ON') and `2'
while the server was running. Setting it to `0' (or `OFF') required a
server restart, as did changing its value from `0' (or `OFF') to `1'
(or `ON') or `2'.

Prior to MySQL 5.1.11, `event_scheduler' could take one of only the 2
values `0'|`OFF' or `1'|`ON', and the default value was `0'|`OFF'. It
was also possible to start and stop the event scheduler thread while the
MySQL server was running.

For more information concerning the reasons for these changes in
behaviour, see Bug#17619 (http://bugs.mysql.com/17619).

Beginning with MySQL 5.1.17, starting the MySQL server with the
`--skip-grant-tables' option causes `event_scheduler' to be set to
`DISABLED', overriding any other value set either on the command line
or in the `my.cnf' or `my.ini' file (Bug#26807
(http://bugs.mysql.com/26807)).

For SQL statements used to create, alter, and drop events, see *Note
events-syntax::.

MySQL 5.1.6 and later provides an `EVENTS' table in the
`INFORMATION_SCHEMA' database. This table can be queried to obtain
information about scheduled events which have been defined on the
server. See *Note events-metadata::, and *Note events-table::, for more
information.

For information regarding event scheduling and the MySQL privilege
system, see *Note events-privileges::.


File: manual.info,  Node: events-syntax,  Next: events-metadata,  Prev: events-overview,  Up: events

25.2 Event Scheduler Syntax
===========================

* Menu:

* alter-event::                  `ALTER EVENT' Syntax
* create-event::                 `CREATE EVENT' Syntax
* drop-event::                   `DROP EVENT' Syntax

MySQL 5.1.6 and later provides several SQL statements for working with
scheduled events:

   * New events are defined using the `CREATE EVENT' statement. See
     *Note create-event::.

   * The definition of an existing event can be changed by means of the
     `ALTER EVENT' statement. See *Note alter-event::.

   * When a scheduled event is no longer wanted or needed, it can be
     deleted from the server by its definer using the `DROP EVENT'
     statement. See *Note drop-event::. (Whether an event persists past
     the end of its schedule also depends on its `ON COMPLETION'
     clause, if it has one. See *Note create-event::.)

     An event can be deleted by any user having the `EVENT' privilege
     for the database on which the event is defined. Prior to MySQL
     5.1.12, a user other than the definer required privileges on the
     `mysql.event' table. See *Note events-privileges::.


File: manual.info,  Node: alter-event,  Next: create-event,  Prev: events-syntax,  Up: events-syntax

25.2.1 `ALTER EVENT' Syntax
---------------------------

     ALTER
         [DEFINER = { USER | CURRENT_USER }]
         EVENT EVENT_NAME
         [ON SCHEDULE SCHEDULE]
         [ON COMPLETION [NOT] PRESERVE]
         [RENAME TO NEW_EVENT_NAME]
         [ENABLE | DISABLE | DISABLE ON SLAVE]
         [COMMENT 'COMMENT']
         [DO SQL_STATEMENT]

The `ALTER EVENT' statement is used to change one or more of the
characteristics of an existing event without the need to drop and
recreate it. The syntax for each of the `DEFINER', `ON SCHEDULE', `ON
COMPLETION', `COMMENT', `ENABLE' / `DISABLE', and `DO' clauses is
exactly the same as when used with `CREATE EVENT'. (See *Note
create-event::.)

Support for the `DEFINER' clause was added in MySQL 5.1.17.

Beginning with MySQL 5.1.12, any user can alter an event defined on a
database for which that user has the `EVENT' privilege. When a user
executes a successful `ALTER EVENT' statement, that user becomes the
definer for the affected event.

(In MySQL 5.1.11 and earlier, an event could be altered only by its
definer, or by a user having the `SUPER' privilege.)

`ALTER EVENT' works only with an existing event:

     mysql> ALTER EVENT no_such_event
          >     ON SCHEDULE
          >       EVERY '2:3' DAY_HOUR;
     `ERROR 1517 (HY000): Unknown event 'no_such_event''

In each of the following examples, assume that the event named
`myevent' is defined as shown here:

     CREATE EVENT myevent
         ON SCHEDULE
           EVERY 6 HOUR
         COMMENT 'A sample comment.'
         DO
           UPDATE myschema.mytable SET mycol = mycol + 1;

The following statement changes the schedule for `myevent' from once
every six hours starting immediately to once every twelve hours,
starting four hours from the time the statement is run:

     ALTER EVENT myevent
         ON SCHEDULE
           EVERY 12 HOUR
         STARTS CURRENT_TIMESTAMP + 4 HOUR;

It is possible to change multiple characteristics of an event in a
single statement. This example changes the SQL statement executed by
`myevent' to one that deletes all records from `mytable'; it also
changes the schedule for the event such that it executes once, one day
after this `ALTER EVENT' statement is run.

     ALTER TABLE myevent
         ON SCHEDULE
           AT CURRENT_TIMESTAMP + INTERVAL 1 DAY
         DO
           TRUNCATE TABLE myschema.mytable;

It is necessary to include only those options in an `ALTER EVENT'
statement which correspond to characteristics that you actually wish to
change; options which are omitted retain their existing values. This
includes any default values for `CREATE EVENT' such as `ENABLE'.

To disable `myevent', use this `ALTER EVENT' statement:

     ALTER EVENT myevent
         DISABLE;

The `ON SCHEDULE' clause may use expressions involving built-in MySQL
functions and user variables to obtain any of the TIMESTAMP or INTERVAL
values which it contains.  You may not use stored routines or
user-defined functions in such expressions, nor may you use any table
references; however, you may use `SELECT FROM DUAL'. This is true for
both `ALTER EVENT' and `CREATE EVENT' statements. Beginning with MySQL
5.1.13, references to stored routines, user-defined functions, and
tables in such cases are specifically disallowed, and fail with an
error (see Bug#22830 (http://bugs.mysql.com/22830)).

An `ALTER EVENT' statement that contains another `ALTER EVENT'
statement in its `DO' clause appears to succeed; however, when the
server attempts to execute the resulting scheduled event, the execution
fails with an error.

To rename an event, use the `ALTER EVENT' statement's `RENAME TO'
clause. This statement renames the event `myevent' to `yourevent':

     ALTER EVENT myevent
         RENAME TO yourevent;

You can also move an event to a different database using `ALTER EVENT
... RENAME TO ...' and `DB_NAME.EVENT_NAME' notation, as shown here:

     ALTER EVENT olddb.myevent
         RENAME TO newdb.myevent;

To execute the previous statement, the user executing it must have the
`EVENT' privilege on both the `olddb' and `newdb' databases.

*Note*:

There is no `RENAME EVENT' statement.

Beginning with MySQL 5.1.18, a third value may also appear in place of
`ENABLED' or `DISABLED'; `DISABLE ON SLAVE' is used on a replication
slave to indicate an event which was created on the master and
replicated to the slave, but which is not executed on the slave.
Normally, `DISABLE ON SLAVE' is set automatically as required; however,
there are some circumstances under which you may want or need to change
it manually. See *Note replication-features-invoked::, for more
information.


File: manual.info,  Node: create-event,  Next: drop-event,  Prev: alter-event,  Up: events-syntax

25.2.2 `CREATE EVENT' Syntax
----------------------------

     CREATE
         [DEFINER = { USER | CURRENT_USER }]
         EVENT
         [IF NOT EXISTS]
         EVENT_NAME
         ON SCHEDULE SCHEDULE
         [ON COMPLETION [NOT] PRESERVE]
         [ENABLE | DISABLE | DISABLE ON SLAVE]
         [COMMENT 'COMMENT']
         DO SQL_STATEMENT;

     SCHEDULE:
         AT TIMESTAMP [+ INTERVAL INTERVAL] ...
       | EVERY INTERVAL
         [STARTS TIMESTAMP [+ INTERVAL interval] ...]
         [ENDS TIMESTAMP [+ INTERVAL interval] ...]

     INTERVAL:
         QUANTITY {YEAR | QUARTER | MONTH | DAY | HOUR | MINUTE |
                   WEEK | SECOND | YEAR_MONTH | DAY_HOUR | DAY_MINUTE |
                   DAY_SECOND | HOUR_MINUTE | HOUR_SECOND | MINUTE_SECOND}

This statement creates and schedules a new event. The minimum
requirements for a valid `CREATE EVENT' statement are as follows:

   * The keywords `CREATE EVENT' plus an event name, which uniquely
     identifies the event in the current schema. (Prior to MySQL
     5.1.12, the event name needed to be unique only among events
     created by the same user on a given database.)

   * An `ON SCHEDULE' clause, which determines when and how often the
     event executes.

   * A `DO' clause, which contains the SQL statement to be executed by
     an event.

This is an example of a minimal `CREATE EVENT' statement:

     CREATE EVENT myevent
         ON SCHEDULE AT CURRENT_TIMESTAMP + INTERVAL 1 HOUR
         DO
           UPDATE myschema.mytable SET mycol = mycol + 1;

The previous statement creates an event named `myevent'. This event
executes once -- one hour following its creation -- by running an SQL
statement that increments the value of the `myschema.mytable' table's
`mycol' column by 1.

The EVENT_NAME must be a valid MySQL identifier with a maximum length
of 64 characters. It may be delimited using back ticks, and may be
qualified with the name of a database schema. An event is associated
with both a MySQL user (the definer) and a schema, and its name must be
unique among names of events within that schema. In general, the rules
governing event names are the same as those for names of stored
routines. See *Note identifiers::.

If no schema is indicated as part of EVENT_NAME, the default (current)
schema is assumed.

*Note*:

MySQL uses case-insensitive comparisons when checking for the
uniqueness of event names. This means that, for example, you cannot
have two events named `myevent' and `MyEvent' in the same database
schema.

The `DEFINER' clause specifies the MySQL account to be used when
checking access privileges at event execution time. If a USER value is
given, it should be a MySQL account in `'USER_NAME'@'HOST_NAME'' format
(the same format used in the `GRANT' statement). The USER_NAME and
HOST_NAME values both are required.  The definer can also be given as
`CURRENT_USER' or `CURRENT_USER()'. The default `DEFINER' value is the
user who executes the `CREATE EVENT' statement. (This is the same as
`DEFINER = CURRENT_USER'.)

The `DEFINER' clause was added in MySQL 5.1.17.  (Prior to MySQL
5.1.12, it was possible for two different users to create different
events having the same name on the same database schema.)

`IF NOT EXISTS' has the same meaning for `CREATE EVENT' as for `CREATE
TABLE': If an event named EVENT_NAME already exists in the same schema,
no action is taken, and no error results. (However, a warning is
generated in such cases.)

The `ON SCHEDULE' clause determines when, how often, and for how long
the SQL_STATEMENT defined for the event repeats. This clause takes one
of two forms:

   * `AT TIMESTAMP' is used for a one-time event. It specifies that the
     event executes one time only at the date and time given by
     TIMESTAMP, which must include both the date and time, or must be
     an expression that resolves to a datetime value. You may use a
     value of either the `DATETIME' or `TIMESTAMP' type for this
     purpose. If the date is in the past, a warning occurs, as shown
     here:

          mysql> SELECT NOW();
          +---------------------+
          | NOW()               |
          +---------------------+
          | 2006-02-10 23:59:01 |
          +---------------------+
          1 row in set (0.04 sec)

          mysql> CREATE EVENT e_totals
              ->     ON SCHEDULE AT '2006-02-10 23:59:00'
              ->     DO INSERT INTO test.totals VALUES (NOW());
          Query OK, 0 rows affected, 1 warning (0.00 sec)

          mysql> SHOW WARNINGS\G
          *************************** 1. row ***************************
            Level: Note
             Code: 1588
          Message: Event execution time is in the past and ON COMPLETION NOT
                   PRESERVE is set. The event was dropped immediately after
                   creation.

     `CREATE EVENT' statements which are themselves invalid -- for
     whatever reason -- fail with an error.

     You may use `CURRENT_TIMESTAMP' to specify the current date and
     time. In such a case, the event acts as soon as it is created.

     To create an event which occurs at some point in the future
     relative to the current date and time -- such as that expressed by
     the phrase `three weeks from now' -- you can use the optional
     clause `+ INTERVAL INTERVAL'. The INTERVAL portion consists of two
     parts, a quantity and a unit of time, and follows the same syntax
     rules that govern intervals used in the `DATE_ADD()' function (see
     *Note date-and-time-functions::. The units keywords are also the
     same, except that you cannot use any units involving microseconds
     when defining an event. With some interval types, complex time
     units may be used. For example, `two minutes and ten seconds' can
     be expressed as `+ INTERVAL '2:10' MINUTE_SECOND'.

     You can also combine intervals. For example, `AT CURRENT_TIMESTAMP
     + INTERVAL 3 WEEK + INTERVAL 2 DAY' is equivalent to `three weeks
     and two days from now'. Each portion of such a clause must begin
     with `+ INTERVAL'.

   * To repeat actions at a regular interval, use an `EVERY' clause. The
     `EVERY' keyword is followed by an INTERVAL as described in the
     previous dicussion of the `AT' keyword.  (`+ INTERVAL' is _not_
     used with `EVERY'.) For example, `EVERY 6 WEEK' means `every six
     weeks'.

     Although `+ INTERVAL' clauses are not allowed in an `EVERY'
     clause, you can use the same complex time units allowed in a `+
     INTERVAL'.

     An `EVERY' clause may also contain an optional `STARTS' clause.
     `STARTS' is followed by a TIMESTAMP value which indicates when the
     action should begin repeating, and may also use `+ INTERVAL
     INTERVAL' in order to specify an amount of time `from now'. For
     example, `EVERY 3 MONTH STARTS CURRENT_TIMESTAMP + 1 WEEK' means
     `every three months, beginning one week from now'. Similarly, you
     can express `every two weeks, beginning six hours and fifteen
     minutes from now' as `EVERY 2 WEEK STARTS CURRENT_TIMESTAMP +
     INTERVAL '6:15' HOUR_MINUTE'.  Not specifying `STARTS' is the same
     as using `STARTS CURRENT_TIMESTAMP' -- that is, the action
     specified for the event begins repeating immediately upon creation
     of the event.

     An `EVERY' clause may also contain an optional `ENDS' clause. The
     `ENDS' keyword is followed by a TIMESTAMP value which tells MySQL
     when the event should stop repeating. You may also use `+ INTERVAL
     INTERVAL' with `ENDS'; for instance, `EVERY 12 HOUR STARTS
     CURRENT_TIMESTAMP + INTERVAL 30 MINUTE ENDS CURRENT_TIMESTAMP +
     INTERVAL 4 WEEK' is equivalent to `every twelve hours, beginning
     thirty minutes from now, and ending four weeks from now'. Not using
     `ENDS' means that the event continues executing indefinitely.

     `ENDS' supports the same syntax for complex time units as `STARTS'
     does.

     You may use `STARTS', `ENDS', both, or neither in an `EVERY'
     clause.

     *Note*:

     Beginning with MySQL 5.1.17, `STARTS' or `ENDS' uses the MySQL
     server's local time zone, as shown in the
     `INFORMATION_SCHEMA.EVENTS' and `mysql.event' tables, as well as
     in the output of `SHOW EVENTS'. Previously, this information was
     stored using UTC (Bug#16420 (http://bugs.mysql.com/16420)).

     Due to this change, the `mysql.event' table must be updated before
     events created in earlier releases can be created, altered,
     viewed, or used in MySQL 5.1.17 or later. You can use
     `mysql_upgrade' for this (see *Note mysql-upgrade::).

     See *Note events-table::, and *Note show-events:: for information
     about columns added in MySQL 5.1.17 to accomodate these changes.

Beginning with MySQL 5.1.18, a third value may also appear in place of
`ENABLED' or `DISABLED'; `DISABLE ON SLAVE' is set for the status of an
event on a replication slave to indicate that the event was created on
the master and replicated to the slave, but is not executed on the
slave. See *Note replication-features-invoked::.

The `ON SCHEDULE' clause may use expressions involving built-in MySQL
functions and user variables to obtain any of the TIMESTAMP or INTERVAL
values which it contains.  You may not use stored functions or
user-defined functions in such expressions, nor may you use any table
references; however, you may use `SELECT FROM DUAL'. This is true for
both `CREATE EVENT' and `ALTER EVENT' statements. Beginning with MySQL
5.1.13, references to stored functions, user-defined functions, and
tables in such cases are specifically disallowed, and fail with an
error (see Bug#22830 (http://bugs.mysql.com/22830)).

Normally, once an event has expired, it is immediately dropped.  You
can override this behavior by specifying `ON COMPLETION PRESERVE'.
Using `ON COMPLETION NOT PRESERVE' merely makes the default
non-persistent behavior explicit.

You can create an event but keep it from being active using the
`DISABLE' keyword. Alternatively, you may use `ENABLE' to make explicit
the default status, which is active. This is most useful in conjunction
with `ALTER EVENT' (see *Note alter-event::).

You may supply a comment for an event using a `COMMENT' clause.
COMMENT may be any string of up to 64 characters that you wish to use
for describing the event. The comment text, being a string literal,
must be surrounded by quotation marks.

The `DO' clause specifies an action carried by the event, and consists
of an SQL statement. Nearly any valid MySQL statement which can be used
in a stored routine can also be used as the action statement for a
scheduled event. (See *Note routine-restrictions::.) For example, the
following event `e_hourly' deletes all rows from the `sessions' table
once per hour, where this table is part of the `site_activity' schema:

     CREATE EVENT e_hourly
         ON SCHEDULE
           EVERY 1 HOUR
         COMMENT 'Clears out sessions table each hour.'
         DO
           DELETE FROM site_activity.sessions;

MySQL stores the `sql_mode' system variable setting that is in effect
at the time an event is created, and always executes the event with
this setting in force, _regardless of the current server SQL mode_.

A `CREATE EVENT' statement that contains an `ALTER EVENT' statement in
its `DO' clause appears to succeed; however, when the server attempts
to execute the resulting scheduled event, the execution fails with an
error.

*Note*:

Statements such as `SELECT' or `SHOW' that merely return a result set
have no effect when used in an event; the output from these is not sent
to the MySQL Monitor, nor is it stored anywhere. However, you can use
statements such as `SELECT ...  INTO' and `INSERT INTO ... SELECT' that
store a result. (See the next example in this section for an instance
of the latter.)

The schema to which an event belongs is the default schema for table
references in the `DO' clause. Any references to tables in other
schemas must be qualified with the proper schema name. (In MySQL 5.1.6,
all tables referenced in event `DO' clauses had to include a reference
to the schema.)

As with stored routines, you can use compound-statement syntax in the
`DO' clause by using the `BEGIN' and `END' keywords, as shown here:

     DELIMITER |

     CREATE EVENT e_daily
         ON SCHEDULE
           EVERY 1 DAY
         COMMENT 'Saves total number of sessions then clears the table each day.'
         DO
           BEGIN
             INSERT INTO site_activity.totals (when, total)
               SELECT CURRENT_TIMESTAMP, COUNT(*)
                 FROM site_activity.sessions;
             DELETE FROM site_activity.sessions;
           END |

     DELIMITER ;

Note the use of the `DELIMITER' command to change the statement
delimiter, as with stored routines. See *Note create-procedure::.

More complex compound statements, such as those used in stored
routines, are possible in an event. This example uses local variables,
an error handler, and a flow control construct:

     DELIMITER |

     CREATE EVENT e
         ON SCHEDULE
           EVERY 5 SECOND
         DO
           BEGIN
             DECLARE v INTEGER;
             DECLARE CONTINUE HANDLER FOR SQLEXCEPTION BEGIN END;

             SET v = 0;

             WHILE v < 5 DO
               INSERT INTO t1 VALUES (0);
               UPDATE t2 SET s1 = s1 + 1;
               SET v = v + 1;
             END WHILE;
         END |

     DELIMITER ;

There is no way to pass parameters directly to or from events; however,
it is possible to invoke a stored routine with parameters:

     CREATE EVENT e_call_myproc
         ON SCHEDULE
           AT CURRENT_TIMESTAMP + INTERVAL 1 DAY
         DO CALL myproc(5, 27);

In addition, if the event's definer has the `SUPER' privilege, that
event may read and write global variables. As granting this privilege
entails a potential for abuse, extreme care must be taken in doing so.

Generally, any statements which are valid in stored routines may be
used for action statements executed by events. For more information
about statements allowable within stored routines, see *Note
stored-procedure-syntax::. You can create an event as part of a stored
routine, but an event cannot be created by another event.


File: manual.info,  Node: drop-event,  Prev: create-event,  Up: events-syntax

25.2.3 `DROP EVENT' Syntax
--------------------------

     DROP EVENT [IF EXISTS] EVENT_NAME

This statement drops the event named EVENT_NAME. The event immediately
ceases being active, and is deleted completely from the server.

If the event does not exist, the error `ERROR 1517 (HY000): Unknown
event 'EVENT_NAME'' results. You can override this and cause the
statement to generate a warning for non-existent events instead using
`IF EXISTS'.

Beginning with MySQL 5.1.12, an event can be dropped by any user having
the `EVENT' privilege on the database schema to which the event to be
dropped belongs. (In MySQL 5.1.11 and earlier, an event could be
dropped only by its definer, or by a user having the `SUPER' privilege.)


File: manual.info,  Node: events-metadata,  Next: events-status-info,  Prev: events-syntax,  Up: events

25.3 Event Metadata
===================

Information about events can be obtained as follows:

   * Query the `EVENTS' table of the `INFORMATION_SCHEMA' database. See
     *Note events-table::.

   * Use the `SHOW EVENTS' statement. See *Note show-events::.

   * Use the `SHOW CREATE EVENT' statement. See *Note
     show-create-event::.

   * A record of events executed on the server can be read from the
     MySQL Server's error log. See *Note events-privileges:: for an
     example.


File: manual.info,  Node: events-status-info,  Next: events-privileges,  Prev: events-metadata,  Up: events

25.4 Event Scheduler Status
===========================

Information about the state of the Event Scheduler for debugging and
troubleshooting purposes can be obtained as follows:

   * In MySQL 5.1.11 `-debug' builds, you can use the `SHOW SCHEDULER
     STATUS' statement; see *Note show-scheduler-status::.

     *Important*:

     This statement was removed in MySQL 5.1.12. We intend to implement
     an SQL statement providing similar functionality in a future MySQL
     release.

   * Beginning with MySQL 5.1.12, event scheduler status information
     can be obtained by running `mysqladmin debug' (see *Note
     mysqladmin::); after running this command, the error log contains
     output relating to the Event Scheduler, similar to what is shown
     here:

          Events status:
          LLA = Last Locked At  LUA = Last Unlocked At
          WOC = Waiting On Condition  DL = Data Locked

          Event scheduler status:
          State      : INITIALIZED
          Thread id  : 0
          LLA        : init_scheduler:313
          LUA        : init_scheduler:318
          WOC        : NO
          Workers    : 0
          Executed   : 0
          Data locked: NO

          Event queue status:
          Element count   : 1
          Data locked     : NO
          Attempting lock : NO
          LLA             : init_queue:148
          LUA             : init_queue:168
          WOC             : NO
          Next activation : 0000-00-00 00:00:00


File: manual.info,  Node: events-privileges,  Next: events-limitations-restrictions,  Prev: events-status-info,  Up: events

25.5 The Event Scheduler and MySQL Privileges
=============================================

To enable or disable the execution of scheduled events, it is necessary
to set the value of the global `event_scheduler' system variable. This
requires the `SUPER' privilege.

MySQL 5.1.6 introduces a privilege governing the creation,
modification, and deletion of events, the `EVENT' privilege. This
privilege can be bestowed using `GRANT'. For example, this `GRANT'
statement confers the `EVENT' privilege for the schema named `myschema'
on the user `jon@ghidora':

     GRANT EVENT ON myschema.* TO jon@ghidora;

(We assume that this user account already exists, and that we wish for
it to remain unchanged otherwise.)

To grant this same user the `EVENT' privilege on all schemas, use the
following statement:

     GRANT EVENT ON *.* TO jon@ghidora;

The `EVENT' privilege has global or schema-level scope. Therefore,
trying to grant it on a single table results in an error as shown:

     mysql> GRANT EVENT ON myschema.mytable TO jon@ghidora;
     `ERROR 1144 (42000): Illegal GRANT/REVOKE command; please
     consult the manual to see which privileges can be used'

It is important to understand that an event is executed with the
privileges of its definer, and that it cannot perform any actions for
which its definer does not have the requisite privileges. For example,
suppose that `jon@ghidora' has the `EVENT' privilege for `myschema'.
Suppose also that this user has the `SELECT' privilege for `myschema',
but no other privileges for this schema. It is possible for
`jon@ghidora' to create a new event such as this one:

     CREATE EVENT e_store_ts
         ON SCHEDULE
           EVERY 10 SECOND
         DO
           INSERT INTO myschema.mytable VALUES (UNIX_TIMESTAMP());

The user waits for a minute or so, and then performs a `SELECT * FROM
mytable;' query, expecting to see several new rows in the table.
Instead, he finds that the table is empty. Since he does not have the
`INSERT' privilege for the table in question, the event has no effect.

If you inspect the MySQL error log (`HOSTNAME.err'), you can see that
the event is executing, but the action it is attempting to perform
fails, as indicated by `RetCode=0':

     060209 22:39:44 [Note]     EVEX EXECUTING event newdb.e [EXPR:10]
     060209 22:39:44 [Note]     EVEX EXECUTED event newdb.e  [EXPR:10]. RetCode=0
     060209 22:39:54 [Note]     EVEX EXECUTING event newdb.e [EXPR:10]
     060209 22:39:54 [Note]     EVEX EXECUTED event newdb.e  [EXPR:10]. RetCode=0
     060209 22:40:04 [Note]     EVEX EXECUTING event newdb.e [EXPR:10]
     060209 22:40:04 [Note]     EVEX EXECUTED event newdb.e  [EXPR:10]. RetCode=0

Since this user very likely does not have access to the error log, he
can verify whether the event's action statement is valid by running it
himself:

     mysql> INSERT INTO myschema.mytable VALUES (UNIX_TIMESTAMP());
     `ERROR 1142 (42000): INSERT command denied to user
     'jon'@'ghidora' for table 'mytable''

Inspection of the `INFORMATION_SCHEMA.EVENTS' table shows that
`e_store_ts' exists and is enabled, but its `LAST_EXECUTED' column is
`NULL':

     mysql> SELECT * FROM INFORMATION_SCHEMA.EVENTS
          >     WHERE EVENT_NAME='e_store_ts'
          >     AND EVENT_SCHEMA='myschema'\G
     *************************** 1. row ***************************
        EVENT_CATALOG: NULL
         EVENT_SCHEMA: myschema
           EVENT_NAME: e_store_ts
              DEFINER: jon@ghidora
           EVENT_BODY: SQL
     EVENT_DEFINITION: INSERT INTO myschema.mytable VALUES (UNIX_TIMESTAMP())
           EVENT_TYPE: RECURRING
           EXECUTE_AT: NULL
       INTERVAL_VALUE: 5
       INTERVAL_FIELD: INTERVAL_SECOND
             SQL_MODE: NULL
               STARTS: 0000-00-00 00:00:00
                 ENDS: 0000-00-00 00:00:00
               STATUS: ENABLED
        ON_COMPLETION: NOT PRESERVE
              CREATED: 2006-02-09 22:36:06
         LAST_ALTERED: 2006-02-09 22:36:06
        LAST_EXECUTED: NULL
        EVENT_COMMENT:
     1 row in set (0.00 sec)

*Note*:

Prior to MySQL 5.1.12, there was no `EVENT_DEFINITION' column, and
`EVENT_BODY' contained the SQL statement or statements to be executed.
See *Note events-table::, for more information.

To rescind the `EVENT' privilege, use the `REVOKE' statement. In this
example, the `EVENT' privilege on the schema `myschema' is removed from
the `jon@ghidora' user account:

     REVOKE EVENT ON myschema.* FROM jon@ghidora;

*Important*:

Revoking the `EVENT' privilege from a user does not delete or disable
any events that may have been created by that user.

An event is not migrated or dropped as a result of renaming or dropping
the user who created it.

For example, suppose that the user `jon@ghidora' has been granted the
`EVENT' and `INSERT' privileges on the `myschema' schema. This user
then creates the following event:

     CREATE EVENT e_insert
         ON SCHEDULE
           EVERY 7 SECOND
         DO
           INSERT INTO myschema.mytable;

After this event has been created, `root' revokes the `EVENT' privilege
for `jon@ghidora'. However, `e_insert' continues to execute, inserting
a new row into `mytable' each seven seconds. The same would be true if
`root' had issued either of these statements:

   * `DROP USER jon@ghidora;'

   * `RENAME USER jon@ghidora TO someotherguy@ghidora;'

You can verify that this is true by examining the `mysql.event' table
(discussed later in this section) or the `INFORMATION_SCHEMA.EVENTS'
table (see *Note events-table::) before and after issuing a `DROP USER'
or `RENAME USER' statement.

Event definitions are stored in the `mysql.event' table, which was
added in MySQL 5.1.6. To drop an event created by another user account,
the MySQL `root' user (or another user with the necessary privileges)
can delete rows from this table. For example, to remove the event
`e_insert' shown previously, `root' can use the following statement:

     DELETE FROM mysql.event
         WHERE db = 'myschema'
           AND definer = 'jon@ghidora'
           AND name = 'e_insert';

It is very important to match the event name, database schema name, and
user account when deleting rows from the `mysql.event' table. This is
because the same user can create different events of the same name in
different schemas.

*Note*:

The namespace for scheduled events changed in MySQL 5.1.12.  Prior to
that MySQL version, different users could create different events
having the same name in the same database; in MySQL 5.1.12 and later,
that is no longer the case. When upgrading to MySQL 5.1.12 or later
from MySQL 5.1.11 or earlier, it is extremely important to make sure
that no events in the same database share the same name, _prior to
performing the upgrade_.

Users' `EVENT' privileges are stored in the `Event_priv' columns of the
`mysql.user' and `mysql.db' tables. In both cases, this column holds
one of the values '`Y'' or '`N''.  '`N'' is the default.
`mysql.user.Event_priv' is set to '`Y'' for a given user only if that
user has the global `EVENT' privilege (that is, if the privilege was
bestowed using `GRANT EVENT ON *.*'). For a schema-level `EVENT'
privilege, `GRANT' creates a row in `mysql.db' and sets that row's `Db'
column to the name of the schema, the `User' column to the name of the
user, and the `Event_priv' column to '`Y''.  There should never be any
need to manipulate these tables directly, since the `GRANT EVENT' and
`REVOKE EVENT' statement perform the required operations on them.

MySQL 5.1.6 introduces five status variables providing counts of
event-related operations (but _not_ of statements executed by events --
see *Note events-limitations-restrictions::). These are:

   * `Com_create_event': The number of `CREATE EVENT' statements
     executed since the last server restart.

   * `Com_alter_event': The number of `ALTER EVENT' statements executed
     since the last server restart.

   * `Com_drop_event': The number of `DROP EVENT' statements executed
     since the last server restart.

   * `Com_show_create_event': The number of `SHOW CREATE EVENT'
     statements executed since the last server restart.

   * `Com_show_events': The number of `SHOW EVENTS' statements executed
     since the last server restart.

You can view current values for all of these at one time by running the
statement `SHOW STATUS LIKE '%event%';'.


File: manual.info,  Node: events-limitations-restrictions,  Prev: events-privileges,  Up: events

25.6 Event Scheduler Limitations and Restrictions
=================================================

This section lists restrictions and limitations applying to event
scheduling in MySQL 5.1.

Qualification of identifiers

In MySQL 5.1.6 only, any table referenced in an event's action
statement must be fully qualified with the name of the schema in which
it occurs (that is, as `SCHEMA_NAME.TABLE_NAME').

Case sensitivity of event identifiers

Beginning with MySQL 5.1.8, event names are handled in case-insensitive
fashion. For example, this means that you cannot have two events in the
same database (and -- prior to MySQL 5.1.12 -- with the same definer)
with the names `anEvent' and `AnEvent'.

*Important*:

If you have events created in MySQL 5.1.7 or earlier which are assigned
to the same database and have the same definer, and whose names differ
only with respect to lettercase, then you must rename these events to
respect case-sensitive handling before upgrading to MySQL 5.1.8 or
later.

Modification of events by stored routines and triggers

An event may not be created, altered, or dropped by a trigger, stored
routine, or another event. An event also may not create, alter, or drop
triggers or stored routines. (Bug#16409 (http://bugs.mysql.com/16409),
Bug#18896 (http://bugs.mysql.com/18896))

Resolution of event timings

Event timings using the intervals `YEAR', `QUARTER', `MONTH', and
`YEAR_MONTH' are resolved in months; those using any other interval are
resolved in seconds. There is no way to cause events scheduled to occur
at the same second to execute in a given order. In addition -- due to
rounding, the nature of threaded applications, and the fact that a
non-zero length of time is required to create events and to signal
their execution -- events may be delayed by as much as 1 or 2 seconds.
However, the time shown in the `INFORMATION_SCHEMA.EVENTS' table's
`LAST_EXECUTED' column or the `mysql.event' table's `last_executed'
column is always accurate to within one second of the time the event
was actually executed.  (See also Bug#16522
(http://bugs.mysql.com/16522).)

Effects on statement counts

Each execution of the statements contained in the body of an event
takes place in a new connection; thus, these statements has no effect
in a given user session on the server's statement counts such as
`Com_select' and `Com_insert' that are displayed by `SHOW STATUS'.
However, such counts _are_ updated in the global scope. (Bug#16422
(http://bugs.mysql.com/16422))

Visibility of events belonging to other users

Prior to MySQL 5.1.12, you could not view another user's events in the
`INFORMATION_SCHEMA.EVENTS' table. In other words, any query made
against this table was treated as though it contained the condition
`DEFINER = CURRENT_USER()' in the `WHERE' clause.

Start times

Events cannot be created with a start time that is in the past.

Latest time supported

Events do not support times later than the end of the Unix Epoch; this
is approximately the beginning of the year 2038.  Prior to MySQL 5.1.8,
handling in scheduled events of dates later than this was buggy;
starting with MySQL 5.1.8, such dates are specifically disallowed by
the Event Scheduler. (Bug#16396 (http://bugs.mysql.com/16396))

Server SQL mode

In MySQL 5.1.6, `INFORMATION_SCHEMA.EVENTS' shows `NULL' in the
`SQL_MODE' column. Beginning with MySQL 5.1.7, the `SQL_MODE' displayed
is that in effect when the event was created.

Dropping or altering events

In MySQL 5.1.6, the only way to drop or alter an event created by a
user who was not the definer of that event was by manipulation of the
`mysql.event' system table by the MySQL `root' user or by another user
with privileges on this table. Beginning with MySQL 5.1.7, `DROP USER'
drops all events for which that user was the definer; also beginning
with MySQL 5.1.7 `DROP SCHEMA' drops all events associated with the
dropped schema.

Database object references in `ON SCHEDULE' clauses

References to stored functions, user-defined functions, and tables in
the `ON SCHEDULE' clauses of `CREATE EVENT' and `ALTER EVENT'
statements are not supported. Beginning with MySQL 5.1.13, these sorts
of references are disallowed. (See Bug#22830
(http://bugs.mysql.com/22830) for more information.)

Disallowed statements

Generally speaking, statements which are not permitted in stored
routines or in SQL prepared statements are also not allowed in the body
of an event. See *Note routine-restrictions::, and *Note
sql-syntax-prepared-statements::, for more information.

Upgrading to MySQL 5.1.18 or later

When upgrading to MySQL 5.1.18 or later from a previous MySQL version
where scheduled events were in use, the upgrade utilities
`mysql_upgrade' and `mysql_fix_privilege_tables' do not accomodate
changes in system tables relating to the Event Scheduler. As a
workaround, you can dump events before the upgrade, then restore them
from the dump afterwards. This issue was fixed in MySQL 5.1.20 (see
Bug#28521 (http://bugs.mysql.com/28521)).


File: manual.info,  Node: views,  Next: information-schema,  Prev: events,  Up: Top

26 Views
********

* Menu:

* alter-view::                   `ALTER VIEW' Syntax
* create-view::                  `CREATE VIEW' Syntax
* drop-view::                    `DROP VIEW' Syntax

Views (including updatable views) are available in MySQL Server 5.1.

Answers to some frequently asked questions concerning views in MySQL
5.1 can be found in *Note faqs-views::.

This chapter discusses the following topics:

   * Creating or altering views with `CREATE VIEW' or `ALTER VIEW'

   * Destroying views with `DROP VIEW'

Discussion of restrictions on use of views is given in *Note
view-restrictions::.

To use views if you have upgraded to MySQL 5.1 from an older release
that did not support views, you should upgrade your grant tables so
that they contain the view-related privileges. See *Note
mysql-upgrade::.

Metadata about views can be obtained from the
`INFORMATION_SCHEMA.VIEWS' table and by using the `SHOW CREATE VIEW'
statement. See *Note views-table::, and *Note show-create-view::.


File: manual.info,  Node: alter-view,  Next: create-view,  Prev: views,  Up: views

26.1 `ALTER VIEW' Syntax
========================

     ALTER
         [ALGORITHM = {UNDEFINED | MERGE | TEMPTABLE}]
         [DEFINER = { USER | CURRENT_USER }]
         [SQL SECURITY { DEFINER | INVOKER }]
         VIEW VIEW_NAME [(COLUMN_LIST)]
         AS SELECT_STATEMENT
         [WITH [CASCADED | LOCAL] CHECK OPTION]

This statement changes the definition of a view, which must exist.  The
syntax is similar to that for `CREATE VIEW' and the effect is the same
as for `CREATE OR REPLACE VIEW'. See *Note create-view::. This statement
requires the `CREATE VIEW' and `DROP' privileges for the view, and some
privilege for each column referred to in the `SELECT' statement. As of
MySQL 5.1.23, `ALTER VIEW' is allowed only to the definer or users with
the `SUPER' privilege.


File: manual.info,  Node: create-view,  Next: drop-view,  Prev: alter-view,  Up: views

26.2 `CREATE VIEW' Syntax
=========================

     CREATE
         [OR REPLACE]
         [ALGORITHM = {UNDEFINED | MERGE | TEMPTABLE}]
         [DEFINER = { USER | CURRENT_USER }]
         [SQL SECURITY { DEFINER | INVOKER }]
         VIEW VIEW_NAME [(COLUMN_LIST)]
         AS SELECT_STATEMENT
         [WITH [CASCADED | LOCAL] CHECK OPTION]

The `CREATE VIEW' statement creates a new view, or replaces an existing
one if the `OR REPLACE' clause is given. If the view does not exist,
`CREATE OR REPLACE VIEW' is the same as `CREATE VIEW'. If the view does
exist, `CREATE OR REPLACE VIEW' is the same as `ALTER VIEW'.

The SELECT_STATEMENT is a `SELECT' statement that provides the
definition of the view. (When you select from the view, you select in
effect using the `SELECT' statement.)  SELECT_STATEMENT can select from
base tables or other views.

The view definition is `frozen' at creation time, so changes to the
underlying tables afterward do not affect the view definition. For
example, if a view is defined as `SELECT *' on a table, new columns
added to the table later do not become part of the view.

The `ALGORITHM' clause affects how MySQL processes the view. The
`DEFINER' and `SQL SECURITY' clauses specify the security context to be
used when checking access privileges at view invocation time. The `WITH
CHECK OPTION' clause can be given to constrain inserts or updates to
rows in tables referenced by the view. These clauses are described
later in this section.

The `CREATE VIEW' statement requires the `CREATE VIEW' privilege for
the view, and some privilege for each column selected by the `SELECT'
statement. For columns used elsewhere in the `SELECT' statement you
must have the `SELECT' privilege. If the `OR REPLACE' clause is
present, you must also have the `DROP' privilege for the view.

A view belongs to a database. By default, a new view is created in the
default database. To create the view explicitly in a given database,
specify the name as DB_NAME.VIEW_NAME when you create it.

     mysql> CREATE VIEW test.v AS SELECT * FROM t;

Base tables and views share the same namespace within a database, so a
database cannot contain a base table and a view that have the same name.

Views must have unique column names with no duplicates, just like base
tables. By default, the names of the columns retrieved by the `SELECT'
statement are used for the view column names. To define explicit names
for the view columns, the optional COLUMN_LIST clause can be given as a
list of comma-separated identifiers. The number of names in COLUMN_LIST
must be the same as the number of columns retrieved by the `SELECT'
statement.

When you modify an existing view, the current view definition is backed
up and saved. It is stored in that table's database directory, in a
sub-folder named `arc'. The backup file will be named
`view_name.frm-00001'. If you alter the view again, the next backup
will be named `view_name.frm-00002'. The three latest view backup
definitions will be stored.

*Note*:

Backed up view definitions will not be preserved by `mysqldump', or any
other such programs, but you could retain it from a file copy. However,
they are not needed for anything, but to provide you with a backup of
your previous view definition.

Also note that while it is safe to remove these, it is not safe to do
so while mysqld is running. If you delete this folder (or sub-files)
while mysqld is running, you will receive an error the next time you
try to alter that view:

     mysql> ALTER VIEW v AS SELECT * FROM t;
     ERROR 6 (HY000): Error on delete of '.\test\arc/v.frm-0004' (Errcode:
     2)

Columns retrieved by the `SELECT' statement can be simple references to
table columns. They can also be expressions that use functions,
constant values, operators, and so forth.

Unqualified table or view names in the `SELECT' statement are
interpreted with respect to the default database. A view can refer to
tables or views in other databases by qualifying the table or view name
with the proper database name.

A view can be created from many kinds of `SELECT' statements. It can
refer to base tables or other views. It can use joins, `UNION', and
subqueries. The `SELECT' need not even refer to any tables. The
following example defines a view that selects two columns from another
table, as well as an expression calculated from those columns:

     mysql> CREATE TABLE t (qty INT, price INT);
     mysql> INSERT INTO t VALUES(3, 50);
     mysql> CREATE VIEW v AS SELECT qty, price, qty*price AS value FROM t;
     mysql> SELECT * FROM v;
     +------+-------+-------+
     | qty  | price | value |
     +------+-------+-------+
     |    3 |    50 |   150 |
     +------+-------+-------+

A view definition is subject to the following restrictions:

   * The `SELECT' statement cannot contain a subquery in the `FROM'
     clause.

   * The `SELECT' statement cannot refer to system or user variables.

   * The `SELECT' statement cannot refer to prepared statement
     parameters.

   * Within a stored routine, the definition cannot refer to routine
     parameters or local variables.

   * Any table or view referred to in the definition must exist.
     However, after a view has been created, it is possible to drop a
     table or view that the definition refers to. In this case, use of
     the view results in an error. To check a view definition for
     problems of this kind, use the `CHECK TABLE' statement.

   * The definition cannot refer to a `TEMPORARY' table, and you cannot
     create a `TEMPORARY' view.

   * The tables named in the view definition must already exist.

   * You cannot associate a trigger with a view.

`ORDER BY' is allowed in a view definition, but it is ignored if you
select from a view using a statement that has its own `ORDER BY'.

For other options or clauses in the definition, they are added to the
options or clauses of the statement that references the view, but the
effect is undefined. For example, if a view definition includes a
`LIMIT' clause, and you select from the view using a statement that has
its own `LIMIT' clause, it is undefined which limit applies. This same
principle applies to options such as `ALL', `DISTINCT', or
`SQL_SMALL_RESULT' that follow the `SELECT' keyword, and to clauses
such as `INTO', `FOR UPDATE', `LOCK IN SHARE MODE', and `PROCEDURE'.

If you create a view and then change the query processing environment
by changing system variables, that may affect the results that you get
from the view:

     mysql> CREATE VIEW v (mycol) AS SELECT 'abc';
     Query OK, 0 rows affected (0.01 sec)

     mysql> SET sql_mode = '';
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT "mycol" FROM v;
     +-------+
     | mycol |
     +-------+
     | mycol |
     +-------+
     1 row in set (0.01 sec)

     mysql> SET sql_mode = 'ANSI_QUOTES';
     Query OK, 0 rows affected (0.00 sec)

     mysql> SELECT "mycol" FROM v;
     +-------+
     | mycol |
     +-------+
     | abc   |
     +-------+
     1 row in set (0.00 sec)

The `DEFINER' and `SQL SECURITY' clauses determine which MySQL account
to use when checking access privileges for the view when a statement is
executed that references the view. They were addded in MySQL 5.1.2. The
legal `SQL SECURITY' characteristic values are `DEFINER' and `INVOKER'.
These indicate that the required privileges must be held by the user who
defined or invoked the view, respectively. The default `SQL SECURITY'
value is `DEFINER'.

If a USER value is given for the `DEFINER' clause, it should be a MySQL
account in `'USER_NAME'@'HOST_NAME'' format (the same format used in
the `GRANT' statement). The USER_NAME and HOST_NAME values both are
required. The definer can also be given as `CURRENT_USER' or
`CURRENT_USER()'. The default `DEFINER' value is the user who executes
the `CREATE VIEW' statement. This is the same as specifying `DEFINER =
CURRENT_USER' explicitly.

If you specify the `DEFINER' clause, these rules determine the legal
`DEFINER' user values:

   * If you do not have the `SUPER' privilege, the only legal USER
     value is your own account, either specified literally or by using
     `CURRENT_USER'. You cannot set the definer to some other account.

   * If you have the `SUPER' privilege, you can specify any
     syntactically legal account name. If the account does not actually
     exist, a warning is generated.

     If the `SQL SECURITY' value is `DEFINER' but the definer account
     does not exist when the view is referenced, an error occurs.

Within a stored routine that is defined with the `SQL SECURITY DEFINER'
characteristic, `CURRENT_USER' returns the routine creator. This also
affects a view defined within such a routine, if the view definition
contains a `DEFINER' value of `CURRENT_USER'.

As of MySQL 5.1.2 (when the `DEFINER' and `SQL SECURITY' clauses were
implemented), view privileges are checked like this:

   * At view definition time, the view creator must have the privileges
     needed to use the top-level objects accessed by the view. For
     example, if the view definition refers to table columns, the
     creator must have privileges for the columns, as described
     previously. If the definition refers to a stored function, only
     the privileges needed to invoke the function can be checked. The
     privileges required when the function runs can be checked only as
     it executes: For different invocations of the function, different
     execution paths within the function might be taken.

   * When a view is referenced, privileges for objects accessed by the
     view are checked against the privileges held by the view creator
     or invoker, depending on whether the `SQL SECURITY' characteristic
     is `DEFINER' or `INVOKER', respectively.

   * If reference to a view causes execution of a stored function,
     privilege checking for statements executed within the function
     depend on whether the function is defined with a `SQL SECURITY'
     characteristic of `DEFINER' or `INVOKER'. If the security
     characteristic is `DEFINER', the function runs with the privileges
     of its creator. If the characteristic is `INVOKER', the function
     runs with the privileges determined by the view's `SQL SECURITY'
     characteristic.

Prior to MySQL 5.1.2 (before the `DEFINER' and `SQL SECURITY' clauses
were implemented), privileges required for objects used in a view are
checked at view creation time.

Example: A view might depend on a stored function, and that function
might invoke other stored routines. For example, the following view
invokes a stored function `f()':

     CREATE VIEW v AS SELECT * FROM t WHERE t.id = f(t.name);

Suppose that `f()' contains a statement such as this:

     IF name IS NULL then
       CALL p1();
     ELSE
       CALL p2();
     END IF;

The privileges required for executing statements within `f()' need to
be checked when `f()' executes. This might mean that privileges are
needed for `p1()' or `p2()', depending on the execution path within
`f()'.  Those privileges must be checked at runtime, and the user who
must possess the privileges is determined by the `SQL SECURITY' values
of the view `v' and the function `f()'.

The `DEFINER' and `SQL SECURITY' clauses for views are extensions to
standard SQL. In standard SQL, views are handled using the rules for
`SQL SECURITY INVOKER'.

If you invoke a view that was created before MySQL 5.1.2, it is treated
as though it was created with a `SQL SECURITY DEFINER' clause and with
a `DEFINER' value that is the same as your account. However, because the
actual definer is unknown, MySQL issues a warning. To make the warning
go away, it is sufficient to re-create the view so that the view
definition includes a `DEFINER' clause.

The optional `ALGORITHM' clause is a MySQL extension to standard SQL.
It affects how MySQL processes the view. `ALGORITHM' takes three values:
`MERGE', `TEMPTABLE', or `UNDEFINED'. The default algorithm is
`UNDEFINED' if no `ALGORITHM' clause is present.

For `MERGE', the text of a statement that refers to the view and the
view definition are merged such that parts of the view definition
replace corresponding parts of the statement.

For `TEMPTABLE', the results from the view are retrieved into a
temporary table, which then is used to execute the statement.

For `UNDEFINED', MySQL chooses which algorithm to use. It prefers
`MERGE' over `TEMPTABLE' if possible, because `MERGE' is usually more
efficient and because a view cannot be updatable if a temporary table
is used.

A reason to choose `TEMPTABLE' explicitly is that locks can be released
on underlying tables after the temporary table has been created and
before it is used to finish processing the statement. This might result
in quicker lock release than the `MERGE' algorithm so that other
clients that use the view are not blocked as long.

A view algorithm can be `UNDEFINED' for three reasons:

   * No `ALGORITHM' clause is present in the `CREATE VIEW' statement.

   * The `CREATE VIEW' statement has an explicit `ALGORITHM =
     UNDEFINED' clause.

   * `ALGORITHM = MERGE' is specified for a view that can be processed
     only with a temporary table. In this case, MySQL generates a
     warning and sets the algorithm to `UNDEFINED'.

As mentioned earlier, `MERGE' is handled by merging corresponding parts
of a view definition into the statement that refers to the view. The
following examples briefly illustrate how the `MERGE' algorithm works.
The examples assume that there is a view `v_merge' that has this
definition:

     CREATE ALGORITHM = MERGE VIEW v_merge (vc1, vc2) AS
     SELECT c1, c2 FROM t WHERE c3 > 100;

Example 1: Suppose that we issue this statement:

     SELECT * FROM v_merge;

MySQL handles the statement as follows:

   * `v_merge' becomes `t'

   * `*' becomes `vc1, vc2', which corresponds to `c1, c2'

   * The view `WHERE' clause is added

The resulting statement to be executed becomes:

     SELECT c1, c2 FROM t WHERE c3 > 100;

Example 2: Suppose that we issue this statement:

     SELECT * FROM v_merge WHERE vc1 < 100;

This statement is handled similarly to the previous one, except that
`vc1 < 100' becomes `c1 < 100' and the view `WHERE' clause is added to
the statement `WHERE' clause using an `AND' connective (and parentheses
are added to make sure the parts of the clause are executed with
correct precedence). The resulting statement to be executed becomes:

     SELECT c1, c2 FROM t WHERE (c3 > 100) AND (c1 < 100);

Effectively, the statement to be executed has a `WHERE' clause of this
form:

     WHERE (select WHERE) AND (view WHERE)

The `MERGE' algorithm requires a one-to-one relationship between the
rows in the view and the rows in the underlying table. If this
relationship does not hold, a temporary table must be used instead.
Lack of a one-to-one relationship occurs if the view contains any of a
number of constructs:

   * Aggregate functions (`SUM()', `MIN()', `MAX()', `COUNT()', and so
     forth)

   * `DISTINCT'

   * `GROUP BY'

   * `HAVING'

   * `UNION' or `UNION ALL'

   * Subquery in the select list

   * Refers only to literal values (in this case, there is no
     underlying table)

Some views are updatable. That is, you can use them in statements such
as `UPDATE', `DELETE', or `INSERT' to update the contents of the
underlying table. For a view to be updatable, there must be a one-to-one
relationship between the rows in the view and the rows in the
underlying table. There are also certain other constructs that make a
view non-updatable. To be more specific, a view is not updatable if it
contains any of the following:

   * Aggregate functions (`SUM()', `MIN()', `MAX()', `COUNT()', and so
     forth)

   * `DISTINCT'

   * `GROUP BY'

   * `HAVING'

   * `UNION' or `UNION ALL'

   * Subquery in the select list

   * Certain joins (see additional join discussion later in this
     section)

   * Non-updatable view in the `FROM' clause

   * A subquery in the `WHERE' clause that refers to a table in the
     `FROM' clause

   * Refers only to literal values (in this case, there is no
     underlying table to update)

   * `ALGORITHM = TEMPTABLE' (use of a temporary table always makes a
     view non-updatable)

With respect to insertability (being updatable with `INSERT'
statements), an updatable view is insertable if it also satisfies these
additional requirements for the view columns:

   * There must be no duplicate view column names.

   * The view must contain all columns in the base table that do not
     have a default value.

   * The view columns must be simple column references and not derived
     columns. A derived column is one that is not a simple column
     reference but is derived from an expression. These are examples of
     derived columns:

          3.14159
          col1 + 3
          UPPER(col2)
          col3 / col4
          (SUBQUERY)

A view that has a mix of simple column references and derived columns
is not insertable, but it can be updatable if you update only those
columns that are not derived. Consider this view:

     CREATE VIEW v AS SELECT col1, 1 AS col2 FROM t;

This view is not insertable because `col2' is derived from an
expression. But it is updatable if the update does not try to update
`col2'. This update is allowable:

     UPDATE v SET col1 = 0;

This update is not allowable because it attempts to update a derived
column:

     UPDATE v SET col2 = 0;

It is sometimes possible for a multiple-table view to be updatable,
assuming that it can be processed with the `MERGE' algorithm. For this
to work, the view must use an inner join (not an outer join or a
`UNION'). Also, only a single table in the view definition can be
updated, so the `SET' clause must name only columns from one of the
tables in the view. Views that use `UNION ALL' are disallowed even
though they might be theoretically updatable, because the implementation
uses temporary tables to process them.

For a multiple-table updatable view, `INSERT' can work if it inserts
into a single table. `DELETE' is not supported.

`INSERT DELAYED' is not supported for views.

If a table contains an `AUTO_INCREMENT' column, inserting into an
insertable view on the table that does not include the `AUTO_INCREMENT'
column does not change the value of `LAST_INSERT_ID()', because the side
effects of inserting default values into columns not part of the view
should not be visible.

The `WITH CHECK OPTION' clause can be given for an updatable view to
prevent inserts or updates to rows except those for which the `WHERE'
clause in the SELECT_STATEMENT is true.

In a `WITH CHECK OPTION' clause for an updatable view, the `LOCAL' and
`CASCADED' keywords determine the scope of check testing when the view
is defined in terms of another view. The `LOCAL' keyword restricts the
`CHECK OPTION' only to the view being defined. `CASCADED' causes the
checks for underlying views to be evaluated as well. When neither
keyword is given, the default is `CASCADED'. Consider the definitions
for the following table and set of views:

     mysql> CREATE TABLE t1 (a INT);
     mysql> CREATE VIEW v1 AS SELECT * FROM t1 WHERE a < 2
         -> WITH CHECK OPTION;
     mysql> CREATE VIEW v2 AS SELECT * FROM v1 WHERE a > 0
         -> WITH LOCAL CHECK OPTION;
     mysql> CREATE VIEW v3 AS SELECT * FROM v1 WHERE a > 0
         -> WITH CASCADED CHECK OPTION;

Here the `v2' and `v3' views are defined in terms of another view, `v1'.
`v2' has a `LOCAL' check option, so inserts are tested only against the
`v2' check. `v3' has a `CASCADED' check option, so inserts are tested
not only against its own check, but against those of underlying views.
The following statements illustrate these differences:

     mysql> INSERT INTO v2 VALUES (2);
     Query OK, 1 row affected (0.00 sec)
     mysql> INSERT INTO v3 VALUES (2);
     ERROR 1369 (HY000): CHECK OPTION failed 'test.v3'

MySQL sets a flag, called the view updatability flag, at `CREATE VIEW'
time. The flag is set to `YES' (true) if `UPDATE' and `DELETE' (and
similar operations) are legal for the view. Otherwise, the flag is set
to `NO' (false). The `IS_UPDATABLE' column in the
`INFORMATION_SCHEMA.VIEWS' table displays the status of this flag. It
means that the server always knows whether a view is updatable. If the
view is not updatable, statements such `UPDATE', `DELETE', and `INSERT'
are illegal and will be rejected. (Note that even if a view is
updatable, it might not be possible to insert into it, as described
elsewhere in this section.)

The updatability of views may be affected by the value of the
`updatable_views_with_limit' system variable. See *Note
server-system-variables::.


File: manual.info,  Node: drop-view,  Prev: create-view,  Up: views

26.3 `DROP VIEW' Syntax
=======================

     DROP VIEW [IF EXISTS]
         VIEW_NAME [, VIEW_NAME] ...
         [RESTRICT | CASCADE]

`DROP VIEW' removes one or more views. You must have the `DROP'
privilege for each view. If any of the views named in the argument list
do not exist, MySQL returns an error indicating by name which
non-existing views it was unable to drop, but it also drops all of the
views in the list that do exist.

The `IF EXISTS' clause prevents an error from occurring for views that
don't exist. When this clause is given, a `NOTE' is generated for each
non-existent view.  See *Note show-warnings::.

`RESTRICT' and `CASCADE', if given, are parsed and ignored.


File: manual.info,  Node: information-schema,  Next: precision-math,  Prev: views,  Up: Top

27 `INFORMATION_SCHEMA' Tables
******************************

* Menu:

* schemata-table::               The `INFORMATION_SCHEMA SCHEMATA' Table
* tables-table::                 The `INFORMATION_SCHEMA TABLES' Table
* columns-table::                The `INFORMATION_SCHEMA COLUMNS' Table
* statistics-table::             The `INFORMATION_SCHEMA STATISTICS' Table
* user-privileges-table::        The `INFORMATION_SCHEMA USER_PRIVILEGES' Table
* schema-privileges-table::      The `INFORMATION_SCHEMA SCHEMA_PRIVILEGES' Table
* table-privileges-table::       The `INFORMATION_SCHEMA TABLE_PRIVILEGES' Table
* column-privileges-table::      The `INFORMATION_SCHEMA COLUMN_PRIVILEGES' Table
* character-sets-table::         The `INFORMATION_SCHEMA CHARACTER_SETS' Table
* collations-table::             The `INFORMATION_SCHEMA COLLATIONS' Table
* collation-character-set-applicability-table::  The `INFORMATION_SCHEMA COLLATION_CHARACTER_SET_APPLICABILITY' Table
* table-constraints-table::      The `INFORMATION_SCHEMA TABLE_CONSTRAINTS' Table
* key-column-usage-table::       The `INFORMATION_SCHEMA KEY_COLUMN_USAGE' Table
* routines-table::               The `INFORMATION_SCHEMA ROUTINES' Table
* views-table::                  The `INFORMATION_SCHEMA VIEWS' Table
* triggers-table::               The `INFORMATION_SCHEMA TRIGGERS' Table
* plugins-table::                The `INFORMATION_SCHEMA PLUGINS' Table
* engines-table::                The `INFORMATION_SCHEMA ENGINES' Table
* partitions-table::             The `INFORMATION_SCHEMA PARTITIONS' Table
* events-table::                 The `INFORMATION_SCHEMA EVENTS' Table
* files-table::                  The `INFORMATION_SCHEMA FILES' Table
* processlist-table::            The `INFORMATION_SCHEMA PROCESSLIST' Table
* referential-constraints-table::  The `INFORMATION_SCHEMA REFERENTIAL_CONSTRAINTS' Table
* status-table::                 The `INFORMATION_SCHEMA GLOBAL_STATUS' and `SESSION_STATUS' Tables
* variables-table::              The `INFORMATION_SCHEMA GLOBAL_VARIABLES' and `SESSION_VARIABLES' Tables
* other-information-schema-tables::  Other `INFORMATION_SCHEMA' Tables
* extended-show::                Extensions to `SHOW' Statements

`INFORMATION_SCHEMA' provides access to database metadata.

_Metadata_ is data about the data, such as the name of a database or
table, the data type of a column, or access privileges. Other terms
that sometimes are used for this information are _data dictionary_ and
_system catalog_.

`INFORMATION_SCHEMA' is the information database, the place that stores
information about all the other databases that the MySQL server
maintains. Inside `INFORMATION_SCHEMA' there are several read-only
tables. They are actually views, not base tables, so there are no files
associated with them.

In effect, we have a database named `INFORMATION_SCHEMA', although the
server does not create a database directory with that name. It is
possible to select `INFORMATION_SCHEMA' as the default database with a
`USE' statement, but it is possible only to read the contents of
tables. You cannot insert into them, update them, or delete from them.

Here is an example of a statement that retrieves information from
`INFORMATION_SCHEMA':

     mysql> SELECT table_name, table_type, engine
         -> FROM information_schema.tables
         -> WHERE table_schema = 'db5'
         -> ORDER BY table_name DESC;
     +------------+------------+--------+
     | table_name | table_type | engine |
     +------------+------------+--------+
     | v56        | VIEW       | NULL   |
     | v3         | VIEW       | NULL   |
     | v2         | VIEW       | NULL   |
     | v          | VIEW       | NULL   |
     | tables     | BASE TABLE | MyISAM |
     | t7         | BASE TABLE | MyISAM |
     | t3         | BASE TABLE | MyISAM |
     | t2         | BASE TABLE | MyISAM |
     | t          | BASE TABLE | MyISAM |
     | pk         | BASE TABLE | InnoDB |
     | loop       | BASE TABLE | MyISAM |
     | kurs       | BASE TABLE | MyISAM |
     | k          | BASE TABLE | MyISAM |
     | into       | BASE TABLE | MyISAM |
     | goto       | BASE TABLE | MyISAM |
     | fk2        | BASE TABLE | InnoDB |
     | fk         | BASE TABLE | InnoDB |
     +------------+------------+--------+
     17 rows in set (0.01 sec)

Explanation: The statement requests a list of all the tables in
database `db5', in reverse alphabetical order, showing just three
pieces of information: the name of the table, its type, and its storage
engine.

Each MySQL user has the right to access these tables, but can see only
the rows in the tables that correspond to objects for which the user
has the proper access privileges. In some cases (for example, the
`ROUTINE_DEFINITION' column in the `INFORMATION_SCHEMA.ROUTINES'
table), users who have insufficient privileges will see `NULL'.

The `SELECT ... FROM INFORMATION_SCHEMA' statement is intended as a
more consistent way to provide access to the information provided by
the various `SHOW' statements that MySQL supports (`SHOW DATABASES',
`SHOW TABLES', and so forth). Using `SELECT' has these advantages,
compared to `SHOW':

   * It conforms to Codd's rules. That is, all access is done on tables.

   * Nobody needs to learn a new statement syntax. Because they already
     know how `SELECT' works, they only need to learn the object names.

   * The implementor need not worry about adding keywords.

   * There are millions of possible output variations, instead of just
     one. This provides more flexibility for applications that have
     varying requirements about what metadata they need.

   * Migration is easier because every other DBMS does it this way.

However, because `SHOW' is popular with MySQL employees and users, and
because it might be confusing were it to disappear, the advantages of
conventional syntax are not a sufficient reason to eliminate `SHOW'. In
fact, along with the implementation of `INFORMATION_SCHEMA', there are
enhancements to `SHOW' as well. These are described in *Note
extended-show::.

There is no difference between the privileges required for `SHOW'
statements and those required to select information from
`INFORMATION_SCHEMA'. In either case, you have to have some privilege
on an object in order to see information about it.

The implementation for the `INFORMATION_SCHEMA' table structures in
MySQL follows the ANSI/ISO SQL:2003 standard Part 11 `Schemata'. Our
intent is approximate compliance with SQL:2003 core feature F021 `Basic
information schema'.

Users of SQL Server 2000 (which also follows the standard) may notice a
strong similarity. However, MySQL has omitted many columns that are not
relevant for our implementation, and added columns that are
MySQL-specific. One such column is the `ENGINE' column in the
`INFORMATION_SCHEMA.TABLES' table.

Although other DBMSs use a variety of names, like `syscat' or `system',
the standard name is `INFORMATION_SCHEMA'.

The following sections describe each of the tables and columns that are
in `INFORMATION_SCHEMA'. For each column, there are three pieces of
information:

   * ``INFORMATION_SCHEMA' Name' indicates the name for the column in
     the `INFORMATION_SCHEMA' table. This corresponds to the standard
     SQL name unless the `Remarks' field says `MySQL extension.'

   * ``SHOW' Name' indicates the equivalent field name in the closest
     `SHOW' statement, if there is one.

   * `Remarks' provides additional information where applicable. If
     this field is `NULL', it means that the value of the column is
     always `NULL'.  If this field says `MySQL extension,' the column is
     a MySQL extension to standard SQL.

To avoid using any name that is reserved in the standard or in DB2, SQL
Server, or Oracle, we changed the names of some columns marked `MySQL
extension'. (For example, we changed `COLLATION' to `TABLE_COLLATION'
in the `TABLES' table.) See the list of reserved words near the end of
this article:
`http://web.archive.org/web/20030201202307/www.dbazine.com/gulutzan5.html'.

The definition for character columns (for example, `TABLES.TABLE_NAME')
is generally `VARCHAR(N) CHARACTER SET utf8' where N is at least 64.
MySQL uses the default collation for this character set
(`utf8_general_ci') for all searches, sorts, comparisons, and other
string operations on such columns. If the default collation is not
correct for your needs, you can force a suitable collation with a
`COLLATE' clause (*Note charset-collate::).

Each section indicates what `SHOW' statement is equivalent to a
`SELECT' that retrieves information from `INFORMATION_SCHEMA', if there
is such a statement. For `SHOW' statements that display information for
the current database if you omit a `FROM DB_NAME' clause, you can often
select information for the current database by adding an `AND
TABLE_SCHEMA = CURRENT_SCHEMA()' condition to the `WHERE' clause of a
query that retrieves information from an `INFORMATION_SCHEMA' table.

*Note*:

At present, there are some missing columns and some columns out of
order. We are working on this and updating the documentation as changes
are made.

For answers to questions that are often asked concerning the
`INFORMATION_SCHEMA' database, see *Note faqs-information-schema::.


File: manual.info,  Node: schemata-table,  Next: tables-table,  Prev: information-schema,  Up: information-schema

27.1 The `INFORMATION_SCHEMA SCHEMATA' Table
============================================

A schema is a database, so the `SCHEMATA' table provides information
about databases.

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
`CATALOG_NAME'                                       `NULL'
`SCHEMA_NAME'                                        Database
`DEFAULT_CHARACTER_SET_NAME'                         
`DEFAULT_COLLATION_NAME'                             
`SQL_PATH'                                           `NULL'

The following statements are equivalent:

     SELECT SCHEMA_NAME AS `Database`
       FROM INFORMATION_SCHEMA.SCHEMATA
       [WHERE SCHEMA_NAME LIKE 'WILD']

     SHOW DATABASES
       [LIKE 'WILD']


File: manual.info,  Node: tables-table,  Next: columns-table,  Prev: schemata-table,  Up: information-schema

27.2 The `INFORMATION_SCHEMA TABLES' Table
==========================================

The `TABLES' table provides information about tables in databases.

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
`TABLE_CATALOG'                                      `NULL'
`TABLE_SCHEMA'                `Table_'...            
`TABLE_NAME'                  `Table_'...            
`TABLE_TYPE'                                         
`ENGINE'                      `Engine'               MySQL extension
`VERSION'                     `Version'              The version number of
                                                     the table's `.frm'
                                                     file, MySQL extension
`ROW_FORMAT'                  `Row_format'           MySQL extension
`TABLE_ROWS'                  `Rows'                 MySQL extension
`AVG_ROW_LENGTH'              `Avg_row_length'       MySQL extension
`DATA_LENGTH'                 `Data_length'          MySQL extension
`MAX_DATA_LENGTH'             `Max_data_length'      MySQL extension
`INDEX_LENGTH'                `Index_length'         MySQL extension
`DATA_FREE'                   `Data_free'            MySQL extension
`AUTO_INCREMENT'              `Auto_increment'       MySQL extension
`CREATE_TIME'                 `Create_time'          MySQL extension
`UPDATE_TIME'                 `Update_time'          MySQL extension
`CHECK_TIME'                  `Check_time'           MySQL extension
`TABLE_COLLATION'             `Collation'            MySQL extension
`CHECKSUM'                    `Checksum'             MySQL extension
`CREATE_OPTIONS'              `Create_options'       MySQL extension
`TABLE_COMMENT'               `Comment'              MySQL extension

*Notes*:

   * `TABLE_SCHEMA' and `TABLE_NAME' are a single field in a `SHOW'
     display, for example `Table_in_db1'.

   * `TABLE_TYPE' should be `BASE TABLE' or `VIEW'. Currently, the
     `TABLES' table does not list `TEMPORARY' tables.

   * For partitioned tables, beginning with MySQL 5.1.9, the `ENGINE'
     column shows the name of the storage engine used by all
     partitions. (Previously, this column showed `PARTITION' for such
     tables.)

   * The `TABLE_ROWS' column is `NULL' if the table is in the
     `INFORMATION_SCHEMA' database. For `InnoDB' tables, the row count
     is only a rough estimate used in SQL optimization.

   * For tables using the `NDBCLUSTER' storage engine, beginning with
     MySQL 5.1.12, the `DATA_LENGTH' column reflects the true amount of
     storage for variable-width columns. (See Bug#18413
     (http://bugs.mysql.com/18413).)

     *Note*:

     Because MySQL Cluster allocates storage for variable-width columns
     in 10-page extents of 32 kilobytes each, space usage for such
     columns is reported in increments of 320 KB.

   * Beginning with MySQL 5.1.24, the `DATA_FREE' column shows the free
     space in bytes for `InnoDB' tables. (Bug#32440
     (http://bugs.mysql.com/32440))

   * We have nothing for the table's default character set.
     `TABLE_COLLATION' is close, because collation names begin with a
     character set name.

   * Beginning with MySQL 5.1.9, the `CREATE_OPTIONS' column shows
     `partitioned' if the table is partitioned.

The following statements are equivalent:

     SELECT table_name FROM INFORMATION_SCHEMA.TABLES
       WHERE table_schema = 'DB_NAME'
       [AND table_name LIKE 'WILD']

     SHOW TABLES
       FROM DB_NAME
       [LIKE 'WILD']


File: manual.info,  Node: columns-table,  Next: statistics-table,  Prev: tables-table,  Up: information-schema

27.3 The `INFORMATION_SCHEMA COLUMNS' Table
===========================================

The `COLUMNS' table provides information about columns in tables.

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
`TABLE_CATALOG'                                      `NULL'
`TABLE_SCHEMA'                                       
`TABLE_NAME'                                         
`COLUMN_NAME'                 `Field'                
`ORDINAL_POSITION'                                   see notes
`COLUMN_DEFAULT'              `Default'              
`IS_NULLABLE'                 `Null'                 
`DATA_TYPE'                   `Type'                 
`CHARACTER_MAXIMUM_LENGTH'    `Type'                 
`CHARACTER_OCTET_LENGTH'                             
`NUMERIC_PRECISION'           `Type'                 
`NUMERIC_SCALE'               `Type'                 
`CHARACTER_SET_NAME'                                 
`COLLATION_NAME'              `Collation'            
`COLUMN_TYPE'                 `Type'                 MySQL extension
`COLUMN_KEY'                  `Key'                  MySQL extension
`EXTRA'                       `Extra'                MySQL extension
`COLUMN_COMMENT'              `Comment'              MySQL extension

*Notes*:

   * In `SHOW', the `Type' display includes values from several
     different `COLUMNS' columns.

   * `ORDINAL_POSITION' is necessary because you might want to say
     `ORDER BY ORDINAL_POSITION'. Unlike `SHOW', `SELECT' does not have
     automatic ordering.

   * `CHARACTER_OCTET_LENGTH' should be the same as
     `CHARACTER_MAXIMUM_LENGTH', except for multi-byte character sets.

   * `CHARACTER_SET_NAME' can be derived from `Collation'. For example,
     if you say `SHOW FULL COLUMNS FROM t', and you see in the
     `Collation' column a value of `latin1_swedish_ci', the character
     set is what's before the first underscore: `latin1'.

The following statements are nearly equivalent:

     SELECT COLUMN_NAME, DATA_TYPE, IS_NULLABLE, COLUMN_DEFAULT
       FROM INFORMATION_SCHEMA.COLUMNS
       WHERE table_name = 'TBL_NAME'
       [AND table_schema = 'DB_NAME']
       [AND column_name LIKE 'WILD']

     SHOW COLUMNS
       FROM TBL_NAME
       [FROM DB_NAME]
       [LIKE 'WILD']


File: manual.info,  Node: statistics-table,  Next: user-privileges-table,  Prev: columns-table,  Up: information-schema

27.4 The `INFORMATION_SCHEMA STATISTICS' Table
==============================================

The `STATISTICS' table provides information about table indexes.

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
`TABLE_CATALOG'                                      `NULL'
`TABLE_SCHEMA'                                       = Database
`TABLE_NAME'                  `Table'                
`NON_UNIQUE'                  `Non_unique'           
`INDEX_SCHEMA'                                       = Database
`INDEX_NAME'                  `Key_name'             
`SEQ_IN_INDEX'                `Seq_in_index'         
`COLUMN_NAME'                 `Column_name'          
`COLLATION'                   `Collation'            
`CARDINALITY'                 `Cardinality'          
`SUB_PART'                    `Sub_part'             MySQL extension
`PACKED'                      `Packed'               MySQL extension
`NULLABLE'                    `Null'                 MySQL extension
`INDEX_TYPE'                  `Index_type'           MySQL extension
`COMMENT'                     `Comment'              MySQL extension

*Notes*:

   * There is no standard table for indexes. The preceding list is
     similar to what SQL Server 2000 returns for `sp_statistics',
     except that we replaced the name `QUALIFIER' with `CATALOG' and we
     replaced the name `OWNER' with `SCHEMA'.

     Clearly, the preceding table and the output from `SHOW INDEX' are
     derived from the same parent. So the correlation is already close.

The following statements are equivalent:

     SELECT * FROM INFORMATION_SCHEMA.STATISTICS
       WHERE table_name = 'TBL_NAME'
       AND table_schema = 'DB_NAME'

     SHOW INDEX
       FROM TBL_NAME
       FROM DB_NAME


File: manual.info,  Node: user-privileges-table,  Next: schema-privileges-table,  Prev: statistics-table,  Up: information-schema

27.5 The `INFORMATION_SCHEMA USER_PRIVILEGES' Table
===================================================

The `USER_PRIVILEGES' table provides information about global
privileges. This information comes from the `mysql.user' grant table.

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
`GRANTEE'                                            `'USER_NAME'@'HOST_NAME''
                                                     value, MySQL extension
`TABLE_CATALOG'                                      `NULL', MySQL
                                                     extension
`PRIVILEGE_TYPE'                                     MySQL extension
`IS_GRANTABLE'                                       MySQL extension

*Notes*:

   * This is a non-standard table. It takes its values from the
     `mysql.user' table.


File: manual.info,  Node: schema-privileges-table,  Next: table-privileges-table,  Prev: user-privileges-table,  Up: information-schema

27.6 The `INFORMATION_SCHEMA SCHEMA_PRIVILEGES' Table
=====================================================

The `SCHEMA_PRIVILEGES' table provides information about schema
(database) privileges. This information comes from the `mysql.db' grant
table.

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
`GRANTEE'                                            `'USER_NAME'@'HOST_NAME''
                                                     value, MySQL extension
`TABLE_CATALOG'                                      `NULL', MySQL
                                                     extension
`TABLE_SCHEMA'                                       MySQL extension
`PRIVILEGE_TYPE'                                     MySQL extension
`IS_GRANTABLE'                                       MySQL extension

*Notes*:

   * This is a non-standard table. It takes its values from the
     `mysql.db' table.


File: manual.info,  Node: table-privileges-table,  Next: column-privileges-table,  Prev: schema-privileges-table,  Up: information-schema

27.7 The `INFORMATION_SCHEMA TABLE_PRIVILEGES' Table
====================================================

The `TABLE_PRIVILEGES' table provides information about table
privileges. This information comes from the `mysql.tables_priv' grant
table.

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
`GRANTEE'                                            `'USER_NAME'@'HOST_NAME''
                                                     value
`TABLE_CATALOG'                                      `NULL'
`TABLE_SCHEMA'                                       
`TABLE_NAME'                                         
`PRIVILEGE_TYPE'                                     
`IS_GRANTABLE'                                       

*Notes*:

   * `PRIVILEGE_TYPE' can contain one (and only one) of these values:
     `SELECT', `INSERT', `UPDATE', `REFERENCES', `ALTER', `INDEX',
     `DROP', `CREATE VIEW'.

The following statements are _not_ equivalent:

     SELECT ... FROM INFORMATION_SCHEMA.TABLE_PRIVILEGES

     SHOW GRANTS ...


File: manual.info,  Node: column-privileges-table,  Next: character-sets-table,  Prev: table-privileges-table,  Up: information-schema

27.8 The `INFORMATION_SCHEMA COLUMN_PRIVILEGES' Table
=====================================================

The `COLUMN_PRIVILEGES' table provides information about column
privileges. This information comes from the `mysql.columns_priv' grant
table.

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
`GRANTEE'                                            `'USER_NAME'@'HOST_NAME''
                                                     value
`TABLE_CATALOG'                                      `NULL'
`TABLE_SCHEMA'                                       
`TABLE_NAME'                                         
`COLUMN_NAME'                                        
`PRIVILEGE_TYPE'                                     
`IS_GRANTABLE'                                       

*Notes*:

   * In the output from `SHOW FULL COLUMNS', the privileges are all in
     one field and in lowercase, for example,
     `select,insert,update,references'. In `COLUMN_PRIVILEGES', there
     is one privilege per row, in uppercase.

   * `PRIVILEGE_TYPE' can contain one (and only one) of these values:
     `SELECT', `INSERT', `UPDATE', `REFERENCES'.

   * If the user has `GRANT OPTION' privilege, `IS_GRANTABLE' should be
     `YES'. Otherwise, `IS_GRANTABLE' should be `NO'. The output does
     not list `GRANT OPTION' as a separate privilege.

The following statements are _not_ equivalent:

     SELECT ... FROM INFORMATION_SCHEMA.COLUMN_PRIVILEGES

     SHOW GRANTS ...


File: manual.info,  Node: character-sets-table,  Next: collations-table,  Prev: column-privileges-table,  Up: information-schema

27.9 The `INFORMATION_SCHEMA CHARACTER_SETS' Table
==================================================

The `CHARACTER_SETS' table provides information about available
character sets.

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
`CHARACTER_SET_NAME'          `Charset'              
`DEFAULT_COLLATE_NAME'        `Default collation'    
`DESCRIPION'                  `Description'          MySQL extension
`MAXLEN'                      `Maxlen'               MySQL extension

The following statements are equivalent:

     SELECT * FROM INFORMATION_SCHEMA.CHARACTER_SETS
       [WHERE name LIKE 'WILD']

     SHOW CHARACTER SET
       [LIKE 'WILD']


File: manual.info,  Node: collations-table,  Next: collation-character-set-applicability-table,  Prev: character-sets-table,  Up: information-schema

27.10 The `INFORMATION_SCHEMA COLLATIONS' Table
===============================================

The `COLLATIONS' table provides information about collations for each
character set.

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
`COLLATION_NAME'              `Collation'            
`CHARACTER_SET_NAME'          `Charset'              MySQL extension
`ID'                          `Id'                   MySQL extension
`IS_DEFAULT'                  `Default'              MySQL extension
`IS_COMPILED'                 `Compiled'             MySQL extension
`SORTLEN'                     `Sortlen'              MySQL extension

The following statements are equivalent:

     SELECT COLLATION_NAME FROM INFORMATION_SCHEMA.COLLATIONS
       [WHERE collation_name LIKE 'WILD']

     SHOW COLLATION
       [LIKE 'WILD']


File: manual.info,  Node: collation-character-set-applicability-table,  Next: table-constraints-table,  Prev: collations-table,  Up: information-schema

27.11 The `INFORMATION_SCHEMA COLLATION_CHARACTER_SET_APPLICABILITY' Table
==========================================================================

The `COLLATION_CHARACTER_SET_APPLICABILITY' table indicates what
character set is applicable for what collation. The columns are
equivalent to the first two display fields that we get from `SHOW
COLLATION'.

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
`COLLATION_NAME'              `Collation'            
`CHARACTER_SET_NAME'          `Charset'              


File: manual.info,  Node: table-constraints-table,  Next: key-column-usage-table,  Prev: collation-character-set-applicability-table,  Up: information-schema

27.12 The `INFORMATION_SCHEMA TABLE_CONSTRAINTS' Table
======================================================

The `TABLE_CONSTRAINTS' table describes which tables have constraints.

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
`CONSTRAINT_CATALOG'                                 `NULL'
`CONSTRAINT_SCHEMA'                                  
`CONSTRAINT_NAME'                                    
`TABLE_SCHEMA'                                       
`TABLE_NAME'                                         
`CONSTRAINT_TYPE'                                    

*Notes*:

   * The `CONSTRAINT_TYPE' value can be `UNIQUE', `PRIMARY KEY', or
     `FOREIGN KEY'.

   * The `UNIQUE' and `PRIMARY KEY' information is about the same as
     what you get from the `Key_name' field in the output from `SHOW
     INDEX' when the `Non_unique' field is `0'.

   * The `CONSTRAINT_TYPE' column can contain one of these values:
     `UNIQUE', `PRIMARY KEY', `FOREIGN KEY', `CHECK'. This is a `CHAR'
     (not `ENUM') column. The `CHECK' value is not available until we
     support `CHECK'.


File: manual.info,  Node: key-column-usage-table,  Next: routines-table,  Prev: table-constraints-table,  Up: information-schema

27.13 The `INFORMATION_SCHEMA KEY_COLUMN_USAGE' Table
=====================================================

The `KEY_COLUMN_USAGE' table describes which key columns have
constraints.

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
`CONSTRAINT_CATALOG'                                 `NULL'
`CONSTRAINT_SCHEMA'                                  
`CONSTRAINT_NAME'                                    
`TABLE_CATALOG'                                      
`TABLE_SCHEMA'                                       
`TABLE_NAME'                                         
`COLUMN_NAME'                                        
`ORDINAL_POSITION'                                   
`POSITION_IN_UNIQUE_CONSTRAINT'                       
`REFERENCED_TABLE_SCHEMA'                            
`REFERENCED_TABLE_NAME'                              
`REFERENCED_COLUMN_NAME'                             

*Notes*:

   * If the constraint is a foreign key, then this is the column of the
     foreign key, not the column that the foreign key references.

   * The value of `ORDINAL_POSITION' is the column's position within
     the constraint, not the column's position within the table. Column
     positions are numbered beginning with 1.

   * The value of `POSITION_IN_UNIQUE_CONSTRAINT' is `NULL' for unique
     and primary-key constraints. For foreign-key constraints, it is
     the ordinal position in key of the table that is being referenced.

     For example, suppose that there are two tables name `t1' and `t3'
     that have the following definitions:

          CREATE TABLE t1
          (
              s1 INT,
              s2 INT,
              s3 INT,
              PRIMARY KEY(s3)
          ) ENGINE=InnoDB;

          CREATE TABLE t3
          (
              s1 INT,
              s2 INT,
              s3 INT,
              KEY(s1),
              CONSTRAINT CO FOREIGN KEY (s2) REFERENCES t1(s3)
          ) ENGINE=InnoDB;

     For those two tables, the `KEY_COLUMN_USAGE' table has two rows:

        * One row with `CONSTRAINT_NAME' = `'PRIMARY'', `TABLE_NAME' =
          `'t1'', `COLUMN_NAME' = `'s3'', `ORDINAL_POSITION' = `1',
          `POSITION_IN_UNIQUE_CONSTRAINT' = `NULL'.

        * One row with `CONSTRAINT_NAME' = `'CO'', `TABLE_NAME' =
          `'t3'', `COLUMN_NAME' = `'s2'', `ORDINAL_POSITION' = `1',
          `POSITION_IN_UNIQUE_CONSTRAINT' = `1'.


File: manual.info,  Node: routines-table,  Next: views-table,  Prev: key-column-usage-table,  Up: information-schema

27.14 The `INFORMATION_SCHEMA ROUTINES' Table
=============================================

The `ROUTINES' table provides information about stored routines (both
procedures and functions). The `ROUTINES' table does not include
user-defined functions (UDFs) at this time.

The column named ``mysql.proc' name' indicates the `mysql.proc' table
column that corresponds to the `INFORMATION_SCHEMA.ROUTINES' table
column, if any.

*`INFORMATION_SCHEMA' Name*   *`mysql.proc' Name*    *Remarks*
`SPECIFIC_NAME'               `specific_name'        
`ROUTINE_CATALOG'                                    `NULL'
`ROUTINE_SCHEMA'              `db'                   
`ROUTINE_NAME'                `name'                 
`ROUTINE_TYPE'                `type'                 `{PROCEDURE|FUNCTION}'
`DTD_IDENTIFIER'                                     data type descriptor
`ROUTINE_BODY'                                       `SQL'
`ROUTINE_DEFINITION'          `body'                 
`EXTERNAL_NAME'                                      `NULL'
`EXTERNAL_LANGUAGE'           `language'             `NULL'
`PARAMETER_STYLE'                                    `SQL'
`IS_DETERMINISTIC'            `is_deterministic'     
`SQL_DATA_ACCESS'             `sql_data_access'      
`SQL_PATH'                                           `NULL'
`SECURITY_TYPE'               `security_type'        
`CREATED'                     `created'              
`LAST_ALTERED'                `modified'             
`SQL_MODE'                    `sql_mode'             MySQL extension
`ROUTINE_COMMENT'             `comment'              MySQL extension
`DEFINER'                     `definer'              MySQL extension
`CHARACTER_SET_CLIENT'                               MySQL extension
`COLLATION_CONNECTION'                               MySQL extension
`DATABASE_COLLATION'                                 MySQL extension

*Notes*:

   * MySQL calculates `EXTERNAL_LANGUAGE' thus:

        * If `mysql.proc.language='SQL'', `EXTERNAL_LANGUAGE' is `NULL'

        * Otherwise, `EXTERNAL_LANGUAGE' is what is in
          `mysql.proc.language'. However, we do not have external
          languages yet, so it is always `NULL'.

   * `CHARACTER_SET_CLIENT' is the session value of the
     `character_set_client' system variable when the routine was
     created.  `COLLATION_CONNECTION' is the session value of the
     `collation_connection' system variable when the routine was
     created.  `DATABASE_COLLATION' is the collation of the database
     with which the routine is associated. These columns were added in
     MySQL 5.1.21.


File: manual.info,  Node: views-table,  Next: triggers-table,  Prev: routines-table,  Up: information-schema

27.15 The `INFORMATION_SCHEMA VIEWS' Table
==========================================

The `VIEWS' table provides information about views in databases. You
must have the `SHOW VIEW' privilege to access this table.

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
`TABLE_CATALOG'                                      `NULL'
`TABLE_SCHEMA'                                       
`TABLE_NAME'                                         
`VIEW_DEFINITION'                                    
`CHECK_OPTION'                                       
`IS_UPDATABLE'                                       
`DEFINER'                                            
`SECURITY_TYPE'                                      
`CHARACTER_SET_CLIENT'                               MySQL extension
`COLLATION_CONNECTION'                               MySQL extension

*Notes*:

   * The `VIEW_DEFINITION' column has most of what you see in the
     `Create Table' field that `SHOW CREATE VIEW' produces. Skip the
     words before `SELECT' and skip the words `WITH CHECK OPTION'.
     Suppose that the original statement was:

          CREATE VIEW v AS
            SELECT s2,s1 FROM t
            WHERE s1 > 5
            ORDER BY s1
            WITH CHECK OPTION;

     Then the view definition looks like this:

          SELECT s2,s1 FROM t WHERE s1 > 5 ORDER BY s1

   * The `CHECK_OPTION' column has a value of `NONE', `CASCADE', or
     `LOCAL'.

   * MySQL sets a flag, called the view updatability flag, at `CREATE
     VIEW' time. The flag is set to `YES' (true) if `UPDATE' and
     `DELETE' (and similar operations) are legal for the view.
     Otherwise, the flag is set to `NO' (false). The `IS_UPDATABLE'
     column in the `VIEWS' table displays the status of this flag. It
     means that the server always knows whether a view is updatable. If
     the view is not updatable, statements such `UPDATE', `DELETE', and
     `INSERT' are illegal and will be rejected.  (Note that even if a
     view is updatable, it might not be possible to insert into it; for
     details, refer to *Note create-view::.)

   * The `DEFINER' column indicates who defined the view.
     `SECURITY_TYPE' has a value of `DEFINER' or `INVOKER'.

   * `CHARACTER_SET_CLIENT' is the session value of the
     `character_set_client' system variable when the view was created.
     `COLLATION_CONNECTION' is the session value of the
     `collation_connection' system variable when the view was created.
     These columns were added in MySQL 5.1.21.


File: manual.info,  Node: triggers-table,  Next: plugins-table,  Prev: views-table,  Up: information-schema

27.16 The `INFORMATION_SCHEMA TRIGGERS' Table
=============================================

The `TRIGGERS' table provides information about triggers. You must have
the `TRIGGER' privilege to access this table (prior to MySQL 5.1.22,
you must have the `SUPER' privilege).

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
`TRIGGER_CATALOG'                                    `NULL'
`TRIGGER_SCHEMA'                                     
`TRIGGER_NAME'                `Trigger'              
`EVENT_MANIPULATION'          `Event'                
`EVENT_OBJECT_CATALOG'                               `NULL'
`EVENT_OBJECT_SCHEMA'                                
`EVENT_OBJECT_TABLE'          `Table'                
`ACTION_ORDER'                                       `0'
`ACTION_CONDITION'                                   `NULL'
`ACTION_STATEMENT'            `Statement'            
`ACTION_ORIENTATION'                                 `ROW'
`ACTION_TIMING'               `Timing'               
`ACTION_REFERENCE_OLD_TABLE'                         `NULL'
`ACTION_REFERENCE_NEW_TABLE'                         `NULL'
`ACTION_REFERENCE_OLD_ROW'                           `OLD'
`ACTION_REFERENCE_NEW_ROW'                           `NEW'
`CREATED'                                            `NULL' (`0')
`SQL_MODE'                                           MySQL extension
`DEFINER'                                            MySQL extension
`CHARACTER_SET_CLIENT'                               MySQL extension
`COLLATION_CONNECTION'                               MySQL extension
`DATABASE_COLLATION'                                 MySQL extension

*Notes*:

   * The `TRIGGER_SCHEMA' and `TRIGGER_NAME' columns contain the name of
     the database in which the trigger occurs and the trigger name,
     respectively.

   * The `EVENT_MANIPULATION' column contains one of the values
     `'INSERT'', `'DELETE'', or `'UPDATE''.

   * As noted in *Note triggers::, every trigger is associated with
     exactly one table. The `EVENT_OBJECT_SCHEMA' and
     `EVENT_OBJECT_TABLE' columns contain the database in which this
     table occurs, and the table's name.

   * The `ACTION_ORDER' statement contains the ordinal position of the
     trigger's action within the list of all similar triggers on the
     same table. Currently, this value is always `0', because it is not
     possible to have more than one trigger with the same
     `EVENT_MANIPULATION' and `ACTION_TIMING' on the same table.

   * The `ACTION_STATEMENT' column contains the statement to be
     executed when the trigger is invoked. This is the same as the text
     displayed in the `Statement' column of the output from `SHOW
     TRIGGERS'. Note that this text uses UTF-8 encoding.

   * The `ACTION_ORIENTATION' column always contains the value `'ROW''.

   * The `ACTION_TIMING' column contains one of the two values
     `'BEFORE'' or `'AFTER''.

   * The columns `ACTION_REFERENCE_OLD_ROW' and
     `ACTION_REFERENCE_NEW_ROW' contain the old and new column
     identifiers, respectively. This means that
     `ACTION_REFERENCE_OLD_ROW' always contains the value `'OLD'' and
     `ACTION_REFERENCE_NEW_ROW' always contains the value `'NEW''.

   * The `SQL_MODE' column shows the server SQL mode that was in effect
     at the time when the trigger was created (and thus which remains
     in effect for this trigger whenever it is invoked, _regardless of
     the current server SQL mode_). The possible range of values for
     this column is the same as that of the `sql_mode' system variable.
     See *Note server-sql-mode::.

   * The `DEFINER' column was added in MySQL 5.1.2. `DEFINER' indicates
     who defined the trigger.

   * `CHARACTER_SET_CLIENT' is the session value of the
     `character_set_client' system variable when the trigger was
     created.  `COLLATION_CONNECTION' is the session value of the
     `collation_connection' system variable when the trigger was
     created.  `DATABASE_COLLATION' is the collation of the database
     with which the trigger is associated. These columns were added in
     MySQL 5.1.21.

   * The following columns currently always contain `NULL':
     `TRIGGER_CATALOG', `EVENT_OBJECT_CATALOG', `ACTION_CONDITION',
     `ACTION_REFERENCE_OLD_TABLE', `ACTION_REFERENCE_NEW_TABLE', and
     `CREATED'.

Example, using the `ins_sum' trigger defined in *Note using-triggers:::

     mysql> SELECT * FROM INFORMATION_SCHEMA.TRIGGERS\G
     *************************** 1. row ***************************
                TRIGGER_CATALOG: NULL
                 TRIGGER_SCHEMA: test
                   TRIGGER_NAME: ins_sum
             EVENT_MANIPULATION: INSERT
           EVENT_OBJECT_CATALOG: NULL
            EVENT_OBJECT_SCHEMA: test
             EVENT_OBJECT_TABLE: account
                   ACTION_ORDER: 0
               ACTION_CONDITION: NULL
               ACTION_STATEMENT: SET @sum = @sum + NEW.amount
             ACTION_ORIENTATION: ROW
                  ACTION_TIMING: BEFORE
     ACTION_REFERENCE_OLD_TABLE: NULL
     ACTION_REFERENCE_NEW_TABLE: NULL
       ACTION_REFERENCE_OLD_ROW: OLD
       ACTION_REFERENCE_NEW_ROW: NEW
                        CREATED: NULL
                       SQL_MODE:
                        DEFINER: me@localhost

See also *Note show-triggers::.


File: manual.info,  Node: plugins-table,  Next: engines-table,  Prev: triggers-table,  Up: information-schema

27.17 The `INFORMATION_SCHEMA PLUGINS' Table
============================================

The `PLUGINS' table provides information about server plugins.

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
`PLUGIN_NAME'                 `Name'                 MySQL extension
`PLUGIN_VERSION'                                     MySQL extension
`PLUGIN_STATUS'               `Status'               MySQL extension
`PLUGIN_TYPE'                 `Type'                 MySQL extension
`PLUGIN_TYPE_VERSION'                                MySQL extension
`PLUGIN_LIBRARY'              `Library'              MySQL extension
`PLUGIN_LIBRARY_VERSION'                             MySQL extension
`PLUGIN_AUTHOR'                                      MySQL extension
`PLUGIN_DESCRIPTION'                                 MySQL extension
`PLUGIN_LICENSE'                                     MySQL extension

*Notes*:

   * The `PLUGINS' table is a non-standard table.  It was added in
     MySQL 5.1.5.

   * The `PLUGIN_LICENSE' column was added in MySQL 5.1.12.

See also *Note show-plugins::.


File: manual.info,  Node: engines-table,  Next: partitions-table,  Prev: plugins-table,  Up: information-schema

27.18 The `INFORMATION_SCHEMA ENGINES' Table
============================================

The `PLUGINS' table provides information about storage engines.

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
`ENGINE'                      `Engine'               MySQL extension
`SUPPORT'                     `Support'              MySQL extension
`COMMENT'                     `Comment'              MySQL extension
`TRANSACTIONS'                `Transactions'         MySQL extension
`XA'                          `XA'                   MySQL extension
`SAVEPOINTS'                  `Savepoints'           MySQL extension

*Notes*:

   * The `ENGINES' table is a non-standard table.  It was added in
     MySQL 5.1.5.

See also *Note show-engines::.


File: manual.info,  Node: partitions-table,  Next: events-table,  Prev: engines-table,  Up: information-schema

27.19 The `INFORMATION_SCHEMA PARTITIONS' Table
===============================================

The `PARTITIONS' table provides information about table partitions. See
*Note partitioning::, for more information about partitioning tables.

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
`TABLE_CATALOG'                                      MySQL extension
`TABLE_SCHEMA'                                       MySQL extension
`TABLE_NAME'                                         MySQL extension
`PARTITION_NAME'                                     MySQL extension
`SUBPARTITION_NAME'                                  MySQL extension
`PARTITION_ORDINAL_POSITION'                         MySQL extension
`SUBPARTITION_ORDINAL_POSITION'                       MySQL extension
`PARTITION_METHOD'                                   MySQL extension
`SUBPARTITION_METHOD'                                MySQL extension
`PARTITION_EXPRESSION'                               MySQL extension
`SUBPARTITION_EXPRESSION'                            MySQL extension
`PARTITION_DESCRIPTION'                              MySQL extension
`TABLE_ROWS'                                         MySQL extension
`AVG_ROW_LENGTH'                                     MySQL extension
`DATA_LENGTH'                                        MySQL extension
`MAX_DATA_LENGTH'                                    MySQL extension
`INDEX_LENGTH'                                       MySQL extension
`DATA_FREE'                                          MySQL extension
`CREATE_TIME'                                        MySQL extension
`UPDATE_TIME'                                        MySQL extension
`CHECK_TIME'                                         MySQL extension
`CHECKSUM'                                           MySQL extension
`PARTITION_COMMENT'                                  MySQL extension
`NODEGROUP'                                          MySQL extension
`TABLESPACE_NAME'                                    MySQL extension

*Notes*:

   * The `PARTITIONS' table is a non-standard table. It was added in
     MySQL 5.1.6.

     Each record in this table corresponds to an individual partition
     or subpartition of a partitioned table.

   * `TABLE_CATALOG': This column is always `NULL'.

   * `TABLE_SCHEMA': This column contains the name of the database to
     which the table belongs.

   * `TABLE_NAME': This column contains the name of the table
     containing the partition.

   * `PARTITION_NAME': The name of the partition.

   * `SUBPARTITION_NAME': If the `PARTITIONS' table record represents a
     subpartition, then this column contains the name of subpartition;
     otherwise it is `NULL'.

   * `PARTITION_ORDINAL_POSITION': All partitions are indexed in the
     same order as they are defined, with `1' being the number assigned
     to the first partition. The indexing can change as partitions are
     added, dropped, and reorganized; the number shown is this column
     reflects the current order, taking into account any indexing
     changes.

   * `SUBPARTITION_ORDINAL_POSITION': Subpartitions within a given
     partition are also indexed and reindexed in the same manner as
     partitions are indexed within a table.

   * `PARTITION_METHOD': One of the values `RANGE', `LIST', `HASH',
     `LINEAR HASH', `KEY', or `LINEAR KEY'; that is, one of the
     available partitioning types as discussed in *Note
     partitioning-types::.

   * `SUBPARTITION_METHOD': One of the values `HASH', `LINEAR HASH',
     `KEY', or `LINEAR KEY'; that is, one of the available
     subpartitioning types as discussed in *Note
     partitioning-subpartitions::.

   * `PARTITION_EXPRESSION': This is the expression for the
     partitioning function used in the `CREATE TABLE' or `ALTER TABLE'
     statement that created the table's current partitioning scheme.

     For example, consider a partitioned table created in the `test'
     database using this statement:

          CREATE TABLE tp (
              c1 INT,
              c2 INT,
              c3 VARCHAR(25)
          )
          PARTITION BY HASH(c1 + c2)
          PARTITIONS 4;

     The `PARTITION_EXPRESSION' column in a PARTITIONS table record for
     a partition from this table displays `c1 + c2', as shown here:

          mysql> SELECT DISTINCT PARTITION_EXPRESSION
               >     FROM INFORMATION_SCHEMA.PARTITIONS
               >     WHERE TABLE_NAME='tp' AND TABLE_SCHEMA='test';
          +----------------------+
          | PARTITION_EXPRESSION |
          +----------------------+
          | c1 + c2              |
          +----------------------+
          1 row in set (0.09 sec)

   * `SUBPARTITION_EXPRESSION': This works in the same fashion for the
     subpartitioning expression that defines the subpartitioning for a
     table as `PARTITION_EXPRESSION' does for the partitioning
     expression used to define a table's partitioning.

     If the table has no subpartitions, then this column is `NULL'.

   * `PARTITION_DESCRIPTION': This column is used for RANGE and LIST
     partitions. For a `RANGE' partition, it contains the value set in
     the partition's `VALUES LESS THAN' clause, which can be either an
     integer or `MAXVALUE'. For a `LIST' partition, this column
     contains the values defined in the partition's `VALUES IN' clause,
     which is a comma-separated list of integer values.

     For partitions whose `PARTITION_METHOD' is other than `RANGE' or
     `LIST', this column is always `NULL'.

   * `TABLE_ROWS': The number of table rows in the partition.

   * `AVG_ROW_LENGTH': The average length of the rows stored in this
     partition or subpartition, in bytes.

     This is the same as `DATA_LENGTH' divided by `TABLE_ROWS'.

   * `DATA_LENGTH': The total length of all rows stored in this
     partition or subpartition, in bytes -- that is, the total number
     of bytes stored in the partition or subpartition.

   * `MAX_DATA_LENGTH': The maximum number of bytes that can be stored
     in this partition or subpartition.

   * `INDEX_LENGTH': The length of the index file for this partition or
     subpartition, in bytes.

   * `DATA_FREE': The number of bytes allocated to the partition or
     subpartition but not used.

   * `CREATE_TIME': The time of the partition's or subpartition's
     creation.

   * `UPDATE_TIME': The time that the partition or subpartition was
     last modified.

   * `CHECK_TIME': The last time that the table to which this partition
     or subpartition belongs was checked.

     *Note*:

     Some storage engines do not update this time; for tables using
     these storage engines, this value is always `NULL'.

   * `CHECKSUM': The checksum value, if any; otherwise, this column is
     `NULL'.

   * `PARTITION_COMMENT': This column contains the text of any comment
     made for the partition.

     The default value for this column is an empty string.

   * `NODEGROUP': This is the nodegroup to which the partition belongs.
     This is relevant only to MySQL Cluster tables; otherwise the value
     of this column is always `0'.

   * `TABLESPACE_NAME': This column contains the name of tablespace to
     which the partition belongs. In MySQL 5.1, the value of this
     column is always `DEFAULT'.

   * *Important*:

     If any partitioned tables created in a MySQL version prior to
     MySQL 5.1.6 are present following an upgrade to MySQL 5.1.6 or
     later, it is not possible to `SELECT' from, `SHOW', or `DESCRIBE'
     the `PARTITIONS' table. See *Note news-5-1-6:: _before_ upgrading
     from MySQL 5.1.5 or earlier to MySQL 5.1.6 or later.

   * A non-partitioned table has one record in
     `INFORMATION_SCHEMA.PARTITIONS'; however, the values of the
     `PARTITION_NAME', `SUBPARTITION_NAME',
     `PARTITION_ORDINAL_POSITION', `SUBPARTITION_ORDINAL_POSITION',
     `PARTITION_METHOD', `SUBPARTITION_METHOD', `PARTITION_EXPRESSION',
     `SUBPARTITION_EXPRESSION', and `PARTITION_DESCRIPTION' columns are
     all `NULL'. (The `PARTITION_COMMENT' column in this case is blank.)

     In MySQL 5.1, there is also only one record in the `PARTITIONS'
     table for a table using the `NDBCLUSTER' storage engine. The same
     columns are also `NULL' (or empty) as for a non-partitioned table.


File: manual.info,  Node: events-table,  Next: files-table,  Prev: partitions-table,  Up: information-schema

27.20 The `INFORMATION_SCHEMA EVENTS' Table
===========================================

The `EVENTS' table provides information about scheduled events, which
are discussed in *Note events::.

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
`EVENT_CATALOG'                                      `NULL', MySQL
                                                     extension
`EVENT_SCHEMA'                `Db'                   MySQL extension
`EVENT_NAME'                  `Name'                 MySQL extension
`DEFINER'                     `Definer'              MySQL extension
`TIME_ZONE'                   `Time zone'            MySQL extension
`EVENT_BODY'                                         MySQL extension
`EVENT_DEFINITION'                                   MySQL extension
`EVENT_TYPE'                  `Type'                 MySQL extension
`EXECUTE_AT'                  `Execute at'           MySQL extension
`INTERVAL_VALUE'              `Interval value'       MySQL extension
`INTERVAL_FIELD'              `Interval field'       MySQL extension
`SQL_MODE'                                           MySQL extension
`STARTS'                      `Starts'               MySQL extension
`ENDS'                        `Ends'                 MySQL extension
`STATUS'                      `Status'               MySQL extension
`ON_COMPLETION'                                      MySQL extension
`CREATED'                                            MySQL extension
`LAST_ALTERED'                                       MySQL extension
`LAST_EXECUTED'                                      MySQL extension
`EVENT_COMMENT'                                      MySQL extension
`ORIGINATOR'                  Originator             MySQL extension
`CHARACTER_SET_CLIENT'                               MySQL extension
`COLLATION_CONNECTION'                               MySQL extension
`DATABASE_COLLATION'                                 MySQL extension

*Notes*:

   * The `EVENTS' table is a non-standard table.  It was added in MySQL
     5.1.6.

   * `EVENT_CATALOG': The value of this column is always `NULL'.

   * `EVENT_SCHEMA': The name of the schema (database) to which this
     event belongs.

   * `EVENT_NAME': The name of the event.

   * `DEFINER': The user who created the event.  Always displayed in
     `'USER_NAME'@'HOST_NAME'' format.

   * `TIME_ZONE': The time zone in effect when schedule for the event
     was last modified. If the event's schedule has not been modified
     since the event was created, then this is the time zone that was
     in effect at the event's creation. The default value is `SYSTEM'.

     This column was added in MySQL 5.1.17. See *Note news-5-1-17::,
     for important information if you are using the Event Scheduler and
     are upgrading from MySQL 5.1.16 (or earlier) to MySQL 5.1.17 (or
     later).

   * `EVENT_BODY': The language used for the statements in the event's
     `DO' clause; in MySQL 5.1, this is always `SQL'.

     This column was added in MySQL 5.1.12. It is not to be confused
     with the column of the same name (now named `EVENT_DEFINITION')
     that existed in earlier MySQL versions.

   * `EVENT_DEFINITION': The text of the SQL statement making up the
     event's `DO' clause; in other words, the statement executed by
     this event.

     *Note*:

     Prior to MySQL 5.1.12, this column was named `EVENT_BODY'.

   * `EVENT_TYPE': One of the two values `ONE TIME' or `RECURRING'.

   * `EXECUTE_AT': For a one-time event, this is the `DATETIME' value
     specified in the `AT' clause of the `CREATE EVENT' statement used
     to create the event, or of the last `ALTER EVENT' statement that
     modified the event. The value shown in this column reflects the
     addition or subtraction of any `INTERVAL' value included in the
     event's `AT' clause.  For example, if an event is created using
     `ON SCHEDULE AT CURRENT_TIMESTAMP + '1:6' DAY_HOUR', and the event
     was created at 2006-02-09 14:05:30, the value shown in this column
     would be `'2006-02-10 20:05:30''.

     If the event's timing is determined by an `EVERY' clause instead
     of an `AT' clause (that is, if the event is recurring), the value
     of this column is `NULL'.

   * `INTERVAL_VALUE': For recurring events, this column contains the
     numeric portion of the event's `EVERY' clause.

     For a one-time event (that is, an event whose timing is determined
     by an `AT' clause), this column's value is `NULL'.

   * `INTERVAL_FIELD': For recurring events, this column contains the
     units portion of the `EVERY' clause governing the timing of the
     event, prefixed with '`INTERVAL_''. Thus, this column contains a
     value such as '`INTERVAL_YEAR'', '`INTERVAL_QUARTER'',
     '`INTERVAL_DAY'', and so on.

     For a one-time event (that is, an event whose timing is determined
     by an `AT' clause), this column's value is `NULL'.

   * `SQL_MODE': The SQL mode in effect at the time the event was
     created or altered.

   * `STARTS': For a recurring event whose definition includes a
     `STARTS' clause, this column contains the corresponding `DATETIME'
     value. As with the `EXECUTE_AT' column, this value resolves any
     expressions used.

     If there is no `STARTS' clause affecting the timing of the event,
     this column is empty. (Prior to MySQL 5.1.8, it contained `NULL'
     in such cases.)

   * `ENDS': For a recurring event whose definition includes a `ENDS'
     clause, this column contains the corresponding `DATETIME' value.
     As with the `EXECUTE_AT' column (see previous example), this value
     resolves any expressions used.

     If there is no `ENDS' clause affecting the timing of the event,
     this column contains `NULL'.

   * `STATUS': One of the three values `ENABLED', `DISABLED', or
     `SLAVESIDE_DISABLED'.

     `SLAVESIDE_DISABLED' was added to the list of possible values for
     this column in MySQL 5.1.18. This value indicates that the
     creation of the event occurred on another MySQL server acting as a
     replication master and was replicated to the current MySQL server
     which is acting as a slave, but the event is not presently being
     executed on the slave. See *Note replication-features-invoked::,
     for more information.

   * `ON_COMPLETION': One of the two values `PRESERVE' or `NOT
     PRESERVE'.

   * `CREATED': The date and time when the event was created. This is a
     `DATETIME' value.

   * `LAST_ALTERED': The date and time when the event was last
     modified. This is a `DATETIME' value. If the event has not been
     modified since its creation, this column holds the same value as
     the `CREATED' column.

   * `LAST_EXECUTED': The date and time when the event last executed. A
     `DATETIME' value. If the event has never executed, this column's
     value is `NULL'.

     Before MySQL 5.1.23, `LAST_EXECUTED' indicates when event finished
     executing. As of 5.1.23, `LAST_EXECUTED' instead indicates when the
     event started. As a result, the `ENDS' column is never less than
     `LAST_EXECUTED'.

   * `EVENT_COMMENT': The text of a comment, if the event has one. If
     there is no comment, the value of this column is an empty string.

   * `ORIGINATOR': The server ID of the MySQL server on which the event
     was created; used in replication.  The default value is 0. This
     column was added in MySQL 5.1.18.

   * `CHARACTER_SET_CLIENT' is the session value of the
     `character_set_client' system variable when the event was created.
     `COLLATION_CONNECTION' is the session value of the
     `collation_connection' system variable when the event was created.
     `DATABASE_COLLATION' is the collation of the database with which
     the event is associated. These columns were added in MySQL 5.1.21.

*Example*: Suppose the user `jon@ghidora' creates an event named
`e_daily', and then modifies it a few minutes later using an `ALTER
EVENT' statement, as shown here:

     DELIMITER |

     CREATE EVENT e_daily
         ON SCHEDULE EVERY 1 DAY
         STARTS CURRENT_TIMESTAMP + INTERVAL 6 HOUR
         DISABLE
         COMMENT 'Saves total number of sessions and
                  clears the table once per day.'
         DO
           BEGIN
             INSERT INTO site_activity.totals (when, total)
               SELECT CURRENT_TIMESTAMP, COUNT(*)
               FROM site_activity.sessions;
             DELETE FROM site_activity.sessions;
           END |

     DELIMITER ;

     ALTER EVENT e_daily
         ENABLED;

(Note that comments can span multiple lines.)

This user can then run the following `SELECT' statement, and obtain the
output shown:

     mysql> SELECT * FROM INFORMATION_SCHEMA.EVENTS
          > WHERE EVENT_NAME = 'e_daily'
          > AND EVENT_SCHEMA = 'myschema'\G

     *************************** 1. row ***************************
       EVENT_CATALOG: NULL
        EVENT_SCHEMA: myschema
          EVENT_NAME: e_daily
             DEFINER: jon@ghidora
          EVENT_BODY: BEGIN
                        INSERT INTO site_activity.totals (when, total)
                          SELECT CURRENT_TIMESTAMP, COUNT(*)
                            FROM site_activity.sessions;
                        DELETE FROM site_activity.sessions;
                      END
          EVENT_TYPE: RECURRING
          EXECUTE_AT: NULL
      INTERVAL_VALUE: 1
      INTERVAL_FIELD: INTERVAL_DAY
            SQL_MODE: NULL
              STARTS: 2006-02-09 10:41:23
                ENDS: NULL
              STATUS: ENABLED
       ON_COMPLETION: DROP
             CREATED: 2006-02-09 14:35:35
        LAST_ALTERED: 2006-02-09 14:41:23
       LAST_EXECUTED: NULL
       EVENT_COMMENT: Saves total number of sessions and
                      clears the table once per day.
          ORIGINATOR: 0

     1 row in set (0.50 sec)

Prior to MySQL 5.1.17, the times displayed in the `STARTS', `ENDS', and
`LAST_EXECUTED' columns were given in terms of Universal Time (GMT or
UTC), regardless of the server's time zone setting (Bug#16420
(http://bugs.mysql.com/16420)). Beginning with MySQL 5.1.17, these
times are all given in terms of local time as determined by the MySQL
server's `time_zone' setting. (The same was true of the `starts',
`ends', and `last_executed' columns of the `mysql.event' table as well
as the `Starts' and `Ends' columns in the output of `SHOW [FULL]
EVENTS'.)

The `CREATED' and `LAST_ALTERED' columns use the server time zone (as
do the `created' and `last_altered' columns of the `mysql.event' table).

See also *Note show-events::.


File: manual.info,  Node: files-table,  Next: processlist-table,  Prev: events-table,  Up: information-schema

27.21 The `INFORMATION_SCHEMA FILES' Table
==========================================

The `FILES' table provides information about the files in which MySQL
`NDB' Disk Data tables are stored.

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
`FILE_ID'                                            MySQL extension
`FILE_NAME'                                          MySQL extension
`FILE_TYPE'                                          MySQL extension
`TABLESPACE_NAME'                                    MySQL extension
`TABLE_CATALOG'                                      MySQL extension
`TABLE_SCHEMA'                                       MySQL extension
`TABLE_NAME'                                         MySQL extension
`LOGFILE_GROUP_NAME'                                 MySQL extension
`LOGFILE_GROUP_NUMBER'                               MySQL extension
`ENGINE'                                             MySQL extension
`FULLTEXT_KEYS'                                      MySQL extension
`DELETED_ROWS'                                       MySQL extension
`UPDATE_COUNT'                                       MySQL extension
`FREE_EXTENTS'                                       MySQL extension
`TOTAL_EXTENTS'                                      MySQL extension
`EXTENT_SIZE'                                        MySQL extension
`INITIAL_SIZE'                                       MySQL extension
`MAXIMUM_SIZE'                                       MySQL extension
`AUTOEXTEND_SIZE'                                    MySQL extension
`CREATION_TIME'                                      MySQL extension
`LAST_UPDATE_TIME'                                   MySQL extension
`LAST_ACCESS_TIME'                                   MySQL extension
`RECOVER_TIME'                                       MySQL extension
`TRANSACTION_COUNTER'                                MySQL extension
`VERSION'                                            MySQL extension
`ROW_FORMAT'                                         MySQL extension
`TABLE_ROWS'                                         MySQL extension
`AVG_ROW_LENGTH'                                     MySQL extension
`DATA_LENGTH'                                        MySQL extension
`MAX_DATA_LENGTH'                                    MySQL extension
`INDEX_LENGTH'                                       MySQL extension
`DATA_FREE'                                          MySQL extension
`CREATE_TIME'                                        MySQL extension
`UPDATE_TIME'                                        MySQL extension
`CHECK_TIME'                                         MySQL extension
`CHECKSUM'                                           MySQL extension
`STATUS'                                             MySQL extension
`EXTRA'                                              MySQL extension

*Notes*:

   * `FILE_ID' column values are auto-generated.

   * `FILE_NAME' is the name of an `UNDO' log file created by `CREATE
     LOGFILE GROUP' or `ALTER LOGFILE GROUP', or of a data file created
     by `CREATE TABLESPACE' or `ALTER TABLESPACE'.

   * `FILE_TYPE' is one of the values `UNDOFILE' or `DATAFILE'.

   * `TABLESPACE_NAME' is the name of the tablespace with which the
     file is associated.

   * In MySQL 5.1, the value of the `TABLESPACE_CATALOG' column is
     always `NULL'.

   * `TABLE_NAME' is the name of the Disk Data table with which the
     file is associated, if any.

   * The `LOGFILE_GROUP_NAME' column gives the name of the log file
     group to which the log file or data file belongs.

   * For an `UNDO' log file, the `LOGFILE_GROUP_NUMBER' contains the
     auto-generated ID number of the log file group to which the log
     file belongs.

   * For a MySQL Cluster Disk Data log file or data file, the value of
     the `ENGINE' column is always `NDB' or `NDBCLUSTER'.

   * For a MySQL Cluster Disk Data log file or data file, the value of
     the `FULLTEXT_KEYS' column is always empty.

   * The `FREE EXTENTS' column displays the number of extents which
     have not yet been used by the file. The `TOTAL EXTENTS' column
     show the total number of extents allocated to the file.

     The difference between these two columns is the number of extents
     currently in use by the file:

          SELECT TOTAL_EXTENTS - FREE_EXTENTS AS extents_used
              FROM INFORMATION_SCHEMA.FILES
              WHERE FILE_NAME = 'myfile.dat';

     You can approximate the amount of disk space in use by the file by
     multiplying this difference by the value of the `EXTENT_SIZE'
     column, which gives the size of an extent for the file in bytes:

          SELECT (TOTAL_EXTENTS - FREE_EXTENTS) * EXTENT_SIZE AS bytes_used
              FROM INFORMATION_SCHEMA.FILES
              WHERE FILE_NAME = 'myfile.dat';

     Similarly, you can estimate the amount of space that remains
     available in a given file by multiplying `FREE_EXTENTS' by
     `EXTENT_SIZE':

          SELECT FREE_EXTENTS * EXTENT_SIZE AS bytes_free
              FROM INFORMATION_SCHEMA.FILES
              WHERE FILE_NAME = 'myfile.dat';

     *Important*:

     The byte values produced by the preceding queries are
     approximations only, and their precision is inversely proportional
     to the value of `EXTENT_SIZE'.  That is, the larger `EXTENT_SIZE'
     becomes, the less accurate the approximations are.

     It is also important to remember that once an extent is used, it
     cannot be freed again without dropping the data file of which it
     is a part. This means that deletes from a Disk Data table do _not_
     release disk space.

     The extent size can be set in a `CREATE TABLESPACE' statement. See
     *Note create-tablespace::, for more information.

   * The `INITIAL_SIZE' column shows the size in bytes of the file.
     This is the same value that was used in the `INITIAL_SIZE' clause
     of the `CREATE LOGFILE GROUP', `ALTER LOGFILE GROUP', `CREATE
     TABLESPACE', or `ALTER TABLESPACE' statement used to create the
     file.

     For MySQL 5.1 Cluster Disk Data files, the value of the
     `MAXIMUM_SIZE' column is always the same as `INITIAL_SIZE', and the
     `AUTOEXTEND_SIZE' column is always empty.

   * The `CREATION_TIME' column shows the date and time when the file
     was created. The `LAST_UPDATE_TIME' column displays the date and
     time when the file was last modified. The `LAST_ACCESSED' column
     provides the date and time when the file was last accessed by the
     server.

     Currently, the values of these columns are as reported by the
     operating system, and are not supplied by the `NDB' storage
     engine. Where no value is provided by the operating system, these
     columns display `0000-00-00 00:00:00'.

   * For MySQL Cluster Disk Data files, the value of the `RECOVER_TIME'
     and `TRANSACTION_COUNTER' columns is always `0'.

   * For MySQL 5.1 Cluster Disk Data files, the following columns are
     always `NULL':

        * `VERSION'

        * `ROW_FORMAT'

        * `TABLE_ROWS'

        * `AVG_ROW_LENGTH'

        * `DATA_LENGTH'

        * `MAX_DATA_LENGTH'

        * `INDEX_LENGTH'

        * `DATA_FREE'

        * `CREATE_TIME'

        * `UPDATE_TIME'

        * `CHECK_TIME'

        * `CHECKSUM'

   * For MySQL Cluster Disk Data files, the value of the `STATUS'
     column is always `NORMAL'.

   * For MySQL Cluster Disk Data files, the `EXTRA' column shows which
     data node the file belongs to, as each data node has its own copy
     of the file.  For example, suppose you use this statement on a
     MySQL Cluster with four data nodes:

          CREATE LOGFILE GROUP mygroup
              ADD UNDOFILE 'new_undo.dat'
              INITIAL_SIZE 2G
              ENGINE NDB;

     After running the `CREATE LOGFILE GROUP' statement successfully,
     you should see a result similar to the one shown here for this
     query against the `FILES' table:

          mysql> SELECT LOGFILE_GROUP_NAME, FILE_TYPE, EXTRA
              ->     FROM INFORMATION_SCHEMA.FILES
              ->     WHERE FILE_NAME = 'new_undo.dat';
          +--------------------+-------------+----------------+
          | LOGFILE_GROUP_NAME | FILE_TYPE   | EXTRA          |
          +--------------------+-------------+----------------+
          | mygroup            | UNDO FILE   | CLUSTER_NODE=3 |
          | mygroup            | UNDO FILE   | CLUSTER_NODE=4 |
          | mygroup            | UNDO FILE   | CLUSTER_NODE=5 |
          | mygroup            | UNDO FILE   | CLUSTER_NODE=6 |
          +--------------------+-------------+----------------+
          4 rows in set (0.01 sec)

   * The `FILES' table is a non-standard table. It was added in MySQL
     5.1.6.

   * Beginning with MySQL 5.1.14, an additional row is present in the
     `FILES' table following the creation of a logfile group. This row
     has `NULL' for the value of the `FILE_NAME' column. For this row,
     the value of the `FILE_ID' column is always `0', that of the
     `FILE_TYPE' column is always `UNDO FILE', and that of the `STATUS'
     column is always `NORMAL'. In MySQL 5.1 the value of the `ENGINE'
     column is always `ndbcluster'.

     This row shows in the `FREE_EXTENTS' column the total number of
     free extents available to all undo files belonging to a given log
     file group whose name and number are shown in the
     `LOGFILE_GROUP_NAME' and `LOGFILE_GROUP_NUMBER' columns,
     respectively.

     Suppose there are no existing log file groups on your MySQL
     Cluster, and you create one using the following statement:

          mysql> CREATE LOGFILE GROUP lg1
              ->   ADD UNDOFILE 'undofile.dat'
              ->   INITIAL_SIZE = 16M
              ->   UNDO_BUFFER_SIZE = 1M
              ->   ENGINE = NDB;
          Query OK, 0 rows affected (3.81 sec)

     You can now see this `NULL' row when you query the `FILES' table:

          mysql> SELECT DISTINCT
              ->   FILE_NAME AS File,
              ->   FREE_EXTENTS AS Free,
              ->   TOTAL_EXTENTS AS Total,
              ->   EXTENT_SIZE AS Size,
              ->   INITIAL_SIZE AS Initial
              ->   FROM INFORMATION_SCHEMA.FILES;
          +--------------+---------+---------+------+----------+
          | File         | Free    | Total   | Size | Initial  |
          +--------------+---------+---------+------+----------+
          | undofile.dat |    NULL | 4194304 |    4 | 16777216 |
          | NULL         | 4184068 |    NULL |    4 |     NULL |
          +--------------+---------+---------+------+----------+
          2 rows in set (0.01 sec)

     The total number of free extents available for undo logging is
     always somewhat less than the sum of the `TOTAL_EXTENTS' column
     values for all undo files in the log file group due to overhead
     required for maintaining the undo files. This can be seen by
     adding a second undo file to the log file group, then repeating the
     previous query against the `FILES' table:

          mysql> ALTER LOGFILE GROUP lg1
              ->   ADD UNDOFILE 'undofile02.dat'
              ->   INITIAL_SIZE = 4M
              ->   ENGINE = NDB;
          Query OK, 0 rows affected (1.02 sec)

          mysql> SELECT DISTINCT
              ->   FILE_NAME AS File,
              ->   FREE_EXTENTS AS Free,
              ->   TOTAL_EXTENTS AS Total,
              ->   EXTENT_SIZE AS Size,
              ->   INITIAL_SIZE AS Initial
              ->   FROM INFORMATION_SCHEMA.FILES;
          +----------------+---------+---------+------+----------+
          | File           | Free    | Total   | Size | Initial  |
          +----------------+---------+---------+------+----------+
          | undofile.dat   |    NULL | 4194304 |    4 | 16777216 |
          | undofile02.dat |    NULL | 1048576 |    4 |  4194304 |
          | NULL           | 5223944 |    NULL |    4 |     NULL |
          +----------------+---------+---------+------+----------+
          3 rows in set (0.01 sec)

     The amount of free space in bytes which is available for undo
     logging by Disk Data tables using this log file group can be
     approximated by multiplying the number of free extents by the
     initial size:

          mysql> SELECT
              ->   FREE_EXTENTS AS 'Free Extents',
              ->   FREE_EXTENTS * EXTENT_SIZE AS 'Free Bytes'
              ->   FROM INFORMATION_SCHEMA.FILES
              ->   WHERE LOGFILE_GROUP_NAME = 'lg1'
              ->   AND FILE_NAME IS NULL;
          +--------------+------------+
          | Free Extents | Free Bytes |
          +--------------+------------+
          |      5223944 |   20895776 |
          +--------------+------------+
          1 row in set (0.02 sec)

     If you create a Disk Data table and then insert some rows into it,
     you can see approximately how much space remains for undo logging
     afterwards, for example:

          mysql> CREATE TABLESPACE ts1
              ->   ADD DATAFILE 'data1.dat'
              ->   USE LOGFILE GROUP lg1
              ->   INITIAL_SIZE 512M
              ->   ENGINE = NDB;
          Query OK, 0 rows affected (8.71 sec)

          mysql> CREATE TABLE dd (
              ->   c1 INT NOT NULL PRIMARY KEY,
              ->   c2 INT,
              ->   c3 DATE
              ->   )
              ->   TABLESPACE ts1 STORAGE DISK
              ->   ENGINE = NDB;
          Query OK, 0 rows affected (2.11 sec)

          mysql> INSERT INTO dd VALUES
              ->   (NULL, 1234567890, '2007-02-02'),
              ->   (NULL, 1126789005, '2007-02-03'),
              ->   (NULL, 1357924680, '2007-02-04'),
              ->   (NULL, 1642097531, '2007-02-05');
          Query OK, 4 rows affected (0.01 sec)

          mysql> SELECT
              ->   FREE_EXTENTS AS 'Free Extents',
              ->   FREE_EXTENTS * EXTENT_SIZE AS 'Free Bytes'
              ->   FROM INFORMATION_SCHEMA.FILES
              ->   WHERE LOGFILE_GROUP_NAME = 'lg1'
              ->   AND FILE_NAME IS NULL;
          +--------------+------------+
          | Free Extents | Free Bytes |
          +--------------+------------+
          |      5207565 |   20830260 |
          +--------------+------------+
          1 row in set (0.01 sec)

   * There are no `SHOW' commands associated with the `FILES' table.

   * For additional examples using the `FILES' table to obtain
     information about Cluster Disk Data tables, see *Note
     mysql-cluster-disk-data::.


File: manual.info,  Node: processlist-table,  Next: referential-constraints-table,  Prev: files-table,  Up: information-schema

27.22 The `INFORMATION_SCHEMA PROCESSLIST' Table
================================================

The `PROCESSLIST' table provides information about which threads are
running.

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
`ID'                          `Id'                   MySQL extension
`USER'                        `User'                 MySQL extension
`HOST'                        `Host'                 MySQL extension
`DB'                          `db'                   MySQL extension
`COMMAND'                     `Command'              MySQL extension
`TIME'                        `Time'                 MySQL extension
`STATE'                       `State'                MySQL extension
`INFO'                        `Info'                 MySQL extension

For an extensive description of the table columns, see *Note
show-processlist::.

*Notes*:

   * The `PROCESSLIST' table is a non-standard table. It was added in
     MySQL 5.1.7.

   * Like the output from the corresponding `SHOW' statement, the
     `PROCESSLIST' table will only show information about your own
     threads, unless you have the `PROCESS' privilege, in which case
     you will see information about other threads, too. As an anonymous
     user, you cannot see any rows at all.

   * If an SQL statement refers to `INFORMATION_SCHEMA.PROCESSLIST',
     then MySQL will populate the entire table once, when statement
     execution begins, so there is read consistency during the
     statement.  There is no read consistency for a multi-statement
     transaction, though.

The following statements are equivalent:

     SELECT * FROM INFORMATION_SCHEMA.PROCESSLIST

     SHOW FULL PROCESSLIST


File: manual.info,  Node: referential-constraints-table,  Next: status-table,  Prev: processlist-table,  Up: information-schema

27.23 The `INFORMATION_SCHEMA REFERENTIAL_CONSTRAINTS' Table
============================================================

The `REFERENTIAL_CONSTRAINTS' table provides information about foreign
keys.

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
CONSTRAINT_CATALOG                                   NULL
CONSTRAINT_SCHEMA                                    
CONSTRAINT_NAME                                      
UNIQUE_CONSTRAINT_CATALOG                            NULL
UNIQUE_CONSTRAINT_SCHEMA                             
UNIQUE_CONSTRAINT_NAME                               
MATCH_OPTION                                         
UPDATE_RULE                                          
DELETE_RULE                                          
TABLE_NAME                                           
REFERENCED_TABLE_NAME                                

*Notes*:

   * The `REFERENTIAL_CONSTRAINTS' table was added in MySQL 5.1.10. The
     `REFERENCED_TABLE_NAME' column was added in MySQL 5.1.16.

   * `TABLE_NAME' has the same value as `TABLE_NAME' in
     `INFORMATION_SCHEMA.TABLE_CONSTRAINTS'.

   * `CONSTRAINT_SCHEMA' and `CONSTRAINT_NAME' identify the foreign key.

   * `UNIQUE_CONSTRAINT_SCHEMA', `UNIQUE_CONSTRAINT_NAME', and
     `REFERENCED_TABLE_NAME' identify the referenced key. (Note: Before
     MySQL 5.1.16, `UNIQUE_CONSTRAINT_NAME' incorrectly named the
     referenced table, not the constraint.)

   * The only valid value at this time for `MATCH_OPTION' is `NONE'.

   * The possible values for `UPDATE_RULE' or `DELETE_RULE' are
     `CASCADE', `SET NULL', `SET DEFAULT', `RESTRICT', `NO ACTION'.


File: manual.info,  Node: status-table,  Next: variables-table,  Prev: referential-constraints-table,  Up: information-schema

27.24 The `INFORMATION_SCHEMA GLOBAL_STATUS' and `SESSION_STATUS' Tables
========================================================================

The `GLOBAL_STATUS' and `SESSION_STATUS' tables provide information
about server status variables. Their contents correspond to the
information produced by the `SHOW GLOBAL STATUS' and `SHOW SESSION
STATUS' statements (see *Note show-status::).

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
VARIABLE_NAME                 Variable_name          
VARIABLE_VALUE                Value                  

*Notes*:

   * The `GLOBAL_STATUS' and `SESSION_STATUS' tables were added in MySQL
     5.1.12.

   * Beginning with MySQL 5.1.19, the `VARIABLE_VALUE' column for each
     of these tables is defined as `VARCHAR(20480)'.  Previously, this
     column had the data type `DECIMAL(22,7)', but was changed to avoid
     loss of data when working with status variables whose values were
     strings (Bug#26994 (http://bugs.mysql.com/26994)).


File: manual.info,  Node: variables-table,  Next: other-information-schema-tables,  Prev: status-table,  Up: information-schema

27.25 The `INFORMATION_SCHEMA GLOBAL_VARIABLES' and `SESSION_VARIABLES' Tables
==============================================================================

The `GLOBAL_VARIABLES' and `SESSION_VARIABLES' tables provide
information about server status variables. Their contents correspond to
the information produced by the `SHOW GLOBAL VARIABLES' and `SHOW
SESSION VARIABLES' statements (see *Note show-variables::).

*`INFORMATION_SCHEMA' Name*   *`SHOW' Name*          *Remarks*
VARIABLE_NAME                 Variable_name          
VARIABLE_VALUE                Value                  

*Notes*:

   * The `GLOBAL_VARIABLES' and `SESSION_VARIABLES' tables were added in
     MySQL 5.1.12.

   * Beginning with MySQL 5.1.19, the `VARIABLE_VALUE' column for each
     of these tables is defined as `VARCHAR(20480)'.  Previously, this
     column had the data type `LONGTEXT'; this was changed in order to
     make these tables consistent with the `GLOBAL_STATUS' and
     `SESSION_STATUS' tables, whose definitions had been changed in
     that version (see *Note status-table::).


File: manual.info,  Node: other-information-schema-tables,  Next: extended-show,  Prev: variables-table,  Up: information-schema

27.26 Other `INFORMATION_SCHEMA' Tables
=======================================

We intend to implement additional `INFORMATION_SCHEMA' tables. In
particular, we acknowledge the need for the `PARAMETERS' table.
(`PARAMETERS' is implemented in MySQL 6.0.)


File: manual.info,  Node: extended-show,  Prev: other-information-schema-tables,  Up: information-schema

27.27 Extensions to `SHOW' Statements
=====================================

Some extensions to `SHOW' statements accompany the implementation of
`INFORMATION_SCHEMA':

   * `SHOW' can be used to get information about the structure of
     `INFORMATION_SCHEMA' itself.

   * Several `SHOW' statements accept a `WHERE' clause that provides
     more flexibility in specifying which rows to display.

`INFORMATION_SCHEMA' is an information database, so its name is
included in the output from `SHOW DATABASES'. Similarly, `SHOW TABLES'
can be used with `INFORMATION_SCHEMA' to obtain a list of its tables:

     mysql> SHOW TABLES FROM INFORMATION_SCHEMA;
     +---------------------------------------+
     | Tables_in_INFORMATION_SCHEMA          |
     +---------------------------------------+
     | CHARACTER_SETS                        |
     | COLLATIONS                            |
     | COLLATION_CHARACTER_SET_APPLICABILITY |
     | COLUMNS                               |
     | COLUMN_PRIVILEGES                     |
     | ENGINES                               |
     | EVENTS                                |
     | FILES                                 |
     | GLOBAL_STATUS                         |
     | GLOBAL_VARIABLES                      |
     | KEY_COLUMN_USAGE                      |
     | PARTITIONS                            |
     | PLUGINS                               |
     | PROCESSLIST                           |
     | REFERENTIAL_CONSTRAINTS               |
     | ROUTINES                              |
     | SCHEMATA                              |
     | SCHEMA_PRIVILEGES                     |
     | SESSION_STATUS                        |
     | SESSION_VARIABLES                     |
     | STATISTICS                            |
     | TABLES                                |
     | TABLE_CONSTRAINTS                     |
     | TABLE_PRIVILEGES                      |
     | TRIGGERS                              |
     | USER_PRIVILEGES                       |
     | VIEWS                                 |
     +---------------------------------------+
     27 rows in set (0.00 sec)

`SHOW COLUMNS' and `DESCRIBE' can display information about the columns
in individual `INFORMATION_SCHEMA' tables.

`SHOW' statements that accept a `LIKE' clause to limit the rows
displayed also allow a `WHERE' clause that enables specification of
more general conditions that selected rows must satisfy:

     SHOW CHARACTER SET
     SHOW COLLATION
     SHOW COLUMNS
     SHOW DATABASES
     SHOW FUNCTION STATUS
     SHOW INDEX
     SHOW OPEN TABLES
     SHOW PROCEDURE STATUS
     SHOW STATUS
     SHOW TABLE STATUS
     SHOW TABLES
     SHOW TRIGGERS
     SHOW VARIABLES

The `WHERE' clause, if present, is evaluated against the column names
displayed by the `SHOW' statement. For example, the `SHOW CHARACTER SET'
statement produces these output columns:

     mysql> SHOW CHARACTER SET;
     +----------+-----------------------------+---------------------+--------+
     | Charset  | Description                 | Default collation   | Maxlen |
     +----------+-----------------------------+---------------------+--------+
     | big5     | Big5 Traditional Chinese    | big5_chinese_ci     |      2 |
     | dec8     | DEC West European           | dec8_swedish_ci     |      1 |
     | cp850    | DOS West European           | cp850_general_ci    |      1 |
     | hp8      | HP West European            | hp8_english_ci      |      1 |
     | koi8r    | KOI8-R Relcom Russian       | koi8r_general_ci    |      1 |
     | latin1   | cp1252 West European        | latin1_swedish_ci   |      1 |
     | latin2   | ISO 8859-2 Central European | latin2_general_ci   |      1 |
     ...

To use a `WHERE' clause with `SHOW CHARACTER SET', you would refer to
those column names. As an example, the following statement displays
information about character sets for which the default collation
contains the string `'japanese'':

     mysql> SHOW CHARACTER SET WHERE `Default collation` LIKE '%japanese%';
     +---------+---------------------------+---------------------+--------+
     | Charset | Description               | Default collation   | Maxlen |
     +---------+---------------------------+---------------------+--------+
     | ujis    | EUC-JP Japanese           | ujis_japanese_ci    |      3 |
     | sjis    | Shift-JIS Japanese        | sjis_japanese_ci    |      2 |
     | cp932   | SJIS for Windows Japanese | cp932_japanese_ci   |      2 |
     | eucjpms | UJIS for Windows Japanese | eucjpms_japanese_ci |      3 |
     +---------+---------------------------+---------------------+--------+

This statement displays the multi-byte character sets:

     mysql> SHOW CHARACTER SET WHERE Maxlen > 1;
     +---------+---------------------------+---------------------+--------+
     | Charset | Description               | Default collation   | Maxlen |
     +---------+---------------------------+---------------------+--------+
     | big5    | Big5 Traditional Chinese  | big5_chinese_ci     |      2 |
     | ujis    | EUC-JP Japanese           | ujis_japanese_ci    |      3 |
     | sjis    | Shift-JIS Japanese        | sjis_japanese_ci    |      2 |
     | euckr   | EUC-KR Korean             | euckr_korean_ci     |      2 |
     | gb2312  | GB2312 Simplified Chinese | gb2312_chinese_ci   |      2 |
     | gbk     | GBK Simplified Chinese    | gbk_chinese_ci      |      2 |
     | utf8    | UTF-8 Unicode             | utf8_general_ci     |      3 |
     | ucs2    | UCS-2 Unicode             | ucs2_general_ci     |      2 |
     | cp932   | SJIS for Windows Japanese | cp932_japanese_ci   |      2 |
     | eucjpms | UJIS for Windows Japanese | eucjpms_japanese_ci |      3 |
     +---------+---------------------------+---------------------+--------+


File: manual.info,  Node: precision-math,  Next: apis,  Prev: information-schema,  Up: Top

28 Precision Math
*****************

* Menu:

* precision-math-numbers::       Types of Numeric Values
* precision-math-decimal-changes::  `DECIMAL' Data Type Changes
* precision-math-expressions::   Expression Handling
* precision-math-rounding::      Rounding Behavior
* precision-math-examples::      Precision Math Examples

MySQL 5.1 provides support for precision math: numeric value handling
that results in extremely accurate results and a high degree control
over invalid values. Precision math is based on these two features:

   * SQL modes that control how strict the server is about accepting or
     rejecting invalid data.

   * The MySQL library for fixed-point arithmetic.

These features have several implications for numeric operations:

   * *Precise calculations*: For exact-value numbers, calculations do
     not introduce floating-point errors. Instead, exact precision is
     used. For example, a number such as `.0001' is treated as an exact
     value rather than as an approximation, and summing it 10,000 times
     produces a result of exactly `1', not a value that merely `close'
     to 1.

   * *Well-defined rounding behavior*: For exact-value numbers, the
     result of `ROUND()' depends on its argument, not on environmental
     factors such as how the underlying C library works.

   * *Platform independence*: Operations on exact numeric values are
     the same across different platforms such as Windows and Unix.

   * *Control over handling of invalid values*: Overflow and division
     by zero are detectable and can be treated as errors. For example,
     you can treat a value that is too large for a column as an error
     rather than having the value truncated to lie within the range of
     the column's data type. Similarly, you can treat division by zero
     as an error rather than as an operation that produces a result of
     `NULL'. The choice of which approach to take is determined by the
     setting of the `sql_mode' system variable.

An important result of these features is that MySQL 5.1 provides a high
degree of compliance with standard SQL.

The following discussion covers several aspects of how precision math
works (including possible incompatibilities with older applications).
At the end, some examples are given that demonstrate how MySQL 5.1
handles numeric operations precisely. For information about using the
`sql_mode' system variable to control the SQL mode, see *Note
server-sql-mode::.


File: manual.info,  Node: precision-math-numbers,  Next: precision-math-decimal-changes,  Prev: precision-math,  Up: precision-math

28.1 Types of Numeric Values
============================

The scope of precision math for exact-value operations includes the
exact-value data types (`DECIMAL' and integer types) and exact-value
numeric literals. Approximate-value data types and numeric literals
still are handled as floating-point numbers.

Exact-value numeric literals have an integer part or fractional part,
or both. They may be signed. Examples: `1', `.2', `3.4', `-5', `-6.78',
`+9.10'.

Approximate-value numeric literals are represented in scientific
notation with a mantissa and exponent. Either or both parts may be
signed. Examples: `1.2E3', `1.2E-3', `-1.2E3', `-1.2E-3'.

Two numbers that look similar need not be both exact-value or both
approximate-value. For example, `2.34' is an exact-value (fixed-point)
number, whereas `2.34E0' is an approximate-value (floating-point)
number.

The `DECIMAL' data type is a fixed-point type and calculations are
exact. In MySQL, the `DECIMAL' type has several synonyms: `NUMERIC',
`DEC', `FIXED'. The integer types also are exact-value types.

The `FLOAT' and `DOUBLE' data types are floating-point types and
calculations are approximate.  In MySQL, types that are synonymous with
`FLOAT' or `DOUBLE' are `DOUBLE PRECISION' and `REAL'.


File: manual.info,  Node: precision-math-decimal-changes,  Next: precision-math-expressions,  Prev: precision-math-numbers,  Up: precision-math

28.2 `DECIMAL' Data Type Changes
================================

This section discusses the characteristics of the `DECIMAL' data type
(and its synonyms) in MySQL 5.1, with particular regard to the
following topics:

   * Maximum number of digits

   * Storage format

   * Storage requirements

   * The non-standard MySQL extension to the upper range of `DECIMAL'
     columns

Possible incompatibilities with applications that are written for older
versions of MySQL are noted throughout this section.

The declaration syntax for a `DECIMAL' column is `DECIMAL(M,D)'.  The
ranges of values for the arguments in MySQL 5.1 are as follows:

   * M is the maximum number of digits (the precision). It has a range
     of 1 to 65. (Older versions of MySQL allowed a range of 1 to 254.)

   * D is the number of digits to the right of the decimal point (the
     scale). It has a range of 0 to 30 and must be no larger than M.

The maximum value of 65 for M means that calculations on `DECIMAL'
values are accurate up to 65 digits. This limit of 65 digits of
precision also applies to exact-value numeric literals, so the maximum
range of such literals is different from before. (In older versions of
MySQL, decimal values could have up to 254 digits. However,
calculations were done using floating-point and thus were approximate,
not exact.)

Values for `DECIMAL' columns in MySQL 5.1 are stored using a binary
format that packs nine decimal digits into four bytes. The storage
requirements for the integer and fractional parts of each value are
determined separately. Each multiple of nine digits requires four
bytes, and any digits left over require some fraction of four bytes. For
example, a `DECIMAL(18,9)' column has nine digits on either side of the
decimal point, so the integer part and the fractional part each require
four bytes. A `DECIMAL(20,10)' column has ten digits on either side of
the decimal point. Each part requires four bytes for nine of the
digits, and one byte for the remaining digit.

The storage required for leftover digits is given by the following
table:

*Leftover Digits*  *Number of Bytes*
0                  0
1                  1
2                  1
3                  2
4                  2
5                  3
6                  3
7                  4
8                  4
9                  4

Unlike some older versions of MySQL (prior to 5.0.3), `DECIMAL' columns
in MySQL 5.1 do not store a leading `+' character or `-' character or
leading `0' digits. If you insert `+0003.1' into a `DECIMAL(5,1)'
column, it is stored as `3.1'. For negative numbers, a literal `-'
character is not stored. Applications that rely on the older behavior
must be modified to account for this change.

`DECIMAL' columns in MySQL 5.1 do not allow values larger than the
range implied by the column definition. For example, a `DECIMAL(3,0)'
column supports a range of `-999' to `999'. A `DECIMAL(M,D)' column
allows at most M - D digits to the left of the decimal point. This is
not compatible with applications relying on older versions of MySQL
that allowed storing an extra digit in lieu of a `+' sign.

The SQL standard requires that the precision of `NUMERIC(M,D)' be
_exactly_ M digits. For `DECIMAL(M,D)', the standard requires a
precision of at least M digits but allows more. In MySQL, `DECIMAL(M,D)'
and `NUMERIC(M,D)' are the same, and both have a precision of exactly M
digits.

For more detailed information about porting applications that rely on
the old treatment of the `DECIMAL' data type, see the `MySQL 5.0
Reference Manual'.


File: manual.info,  Node: precision-math-expressions,  Next: precision-math-rounding,  Prev: precision-math-decimal-changes,  Up: precision-math

28.3 Expression Handling
========================

With precision math, exact-value numbers are used as given whenever
possible. For example, numbers in comparisons are used exactly as given
without a change in value. In strict SQL mode, for `INSERT' into a
column with an exact data type (`DECIMAL' or integer), a number is
inserted with its exact value if it is within the column range. When
retrieved, the value should be the same as what was inserted.  (Without
strict mode, truncation for `INSERT' is allowable.)

Handling of a numeric expression depends on what kind of values the
expression contains:

   * If any approximate values are present, the expression is
     approximate and is evaluated using floating-point arithmetic.

   * If no approximate values are present, the expression contains only
     exact values. If any exact value contains a fractional part (a
     value following the decimal point), the expression is evaluated
     using `DECIMAL' exact arithmetic and has a precision of 65 digits.
     (The term `exact' is subject to the limits of what can be
     represented in binary. For example, `1.0/3.0' can be approximated
     in decimal notation as `.333...', but not written as an exact
     number, so `(1.0/3.0)*3.0' does not evaluate to exactly `1.0'.)

   * Otherwise, the expression contains only integer values. The
     expression is exact and is evaluated using integer arithmetic and
     has a precision the same as `BIGINT' (64 bits).

If a numeric expression contains any strings, they are converted to
double-precision floating-point values and the expression is
approximate.

Inserts into numeric columns are affected by the SQL mode, which is
controlled by the `sql_mode' system variable.  (See *Note
server-sql-mode::.) The following discussion mentions strict mode
(selected by the `STRICT_ALL_TABLES' or `STRICT_TRANS_TABLES' mode
values) and `ERROR_FOR_DIVISION_BY_ZERO'. To turn on all restrictions,
you can simply use `TRADITIONAL' mode, which includes both strict mode
values and `ERROR_FOR_DIVISION_BY_ZERO':

     mysql> SET sql_mode='TRADITIONAL';

If a number is inserted into an exact type column (`DECIMAL' or
integer), it is inserted with its exact value if it is within the
column range.

If the value has too many digits in the fractional part, rounding
occurs and a warning is generated. Rounding is done as described in
*Note precision-math-rounding::.

If the value has too many digits in the integer part, it is too large
and is handled as follows:

   * If strict mode is not enabled, the value is truncated to the
     nearest legal value and a warning is generated.

   * If strict mode is enabled, an overflow error occurs.

Underflow is not detected, so underflow handing is undefined.

By default, division by zero produces a result of `NULL' and no
warning. With the `ERROR_FOR_DIVISION_BY_ZERO' SQL mode enabled, MySQL
handles division by zero differently:

   * If strict mode is not enabled, a warning occurs.

   * If strict mode is enabled, inserts and updates involving division
     by zero are prohibited, and an error occurs.

In other words, inserts and updates involving expressions that perform
division by zero can be treated as errors, but this requires
`ERROR_FOR_DIVISION_BY_ZERO' in addition to strict mode.

Suppose that we have this statement:

     INSERT INTO t SET i = 1/0;

This is what happens for combinations of strict and
`ERROR_FOR_DIVISION_BY_ZERO' modes:

*`sql_mode' Value*                   *Result*
`''' (Default)                       No warning, no error; `i' is set to
                                     `NULL'.
strict                               No warning, no error; `i' is set to
                                     `NULL'.
`ERROR_FOR_DIVISION_BY_ZERO'         Warning, no error; `i' is set to
                                     `NULL'.
strict,`ERROR_FOR_DIVISION_BY_ZERO'  Error condition; no row is inserted.

For inserts of strings into numeric columns, conversion from string to
number is handled as follows if the string has non-numeric contents:

   * A string that does not begin with a number cannot be used as a
     number and produces an error in strict mode, or a warning
     otherwise. _This includes the empty string_.

   * A string that begins with a number can be converted, but the
     trailing non-numeric portion is truncated. If the truncated
     portion contains anything other than spaces, this produces an
     error in strict mode, or a warning otherwise.


File: manual.info,  Node: precision-math-rounding,  Next: precision-math-examples,  Prev: precision-math-expressions,  Up: precision-math

28.4 Rounding Behavior
======================

This section discusses precision math rounding for the `ROUND()'
function and for inserts into columns with exact-value types (`DECIMAL'
and integer).

The `ROUND()' function rounds differently depending on whether its
argument is exact or approximate:

   * For exact-value numbers, `ROUND()' uses the `round half up' rule:
     A value with a fractional part of .5 or greater is rounded up to
     the next integer if positive or down to the next integer if
     negative. (In other words, it is rounded away from zero.) A value
     with a fractional part less than .5 is rounded down to the next
     integer if positive or up to the next integer if negative.

   * For approximate-value numbers, the result depends on the C
     library. On many systems, this means that `ROUND()' uses the `round
     to nearest even' rule: A value with any fractional part is rounded
     to the nearest even integer.

The following example shows how rounding differs for exact and
approximate values:

     mysql> SELECT ROUND(2.5), ROUND(25E-1);
     +------------+--------------+
     | ROUND(2.5) | ROUND(25E-1) |
     +------------+--------------+
     | 3          |            2 |
     +------------+--------------+

For inserts into a `DECIMAL' or integer column, the target is an exact
data type, so rounding uses `round half up,' regardless of whether the
value to be inserted is exact or approximate:

     mysql> CREATE TABLE t (d DECIMAL(10,0));
     Query OK, 0 rows affected (0.00 sec)

     mysql> INSERT INTO t VALUES(2.5),(2.5E0);
     Query OK, 2 rows affected, 2 warnings (0.00 sec)
     Records: 2  Duplicates: 0  Warnings: 2

     mysql> SELECT d FROM t;
     +------+
     | d    |
     +------+
     | 3    |
     | 3    |
     +------+


File: manual.info,  Node: precision-math-examples,  Prev: precision-math-rounding,  Up: precision-math

28.5 Precision Math Examples
============================

This section provides some examples that show precision math query
results in MySQL 5.1.

*Example 1*. Numbers are used with their exact value as given when
possible:

     mysql> SELECT .1 + .2 = .3;
     +--------------+
     | .1 + .2 = .3 |
     +--------------+
     |            1 |
     +--------------+

For floating-point values, results are inexact:

     mysql> SELECT .1E0 + .2E0 = .3E0;
     +--------------------+
     | .1E0 + .2E0 = .3E0 |
     +--------------------+
     |                  0 |
     +--------------------+

Another way to see the difference in exact and approximate value
handling is to add a small number to a sum many times. Consider the
following stored procedure, which adds `.0001' to a variable 1,000
times.

     CREATE PROCEDURE p ()
     BEGIN
       DECLARE i INT DEFAULT 0;
       DECLARE d DECIMAL(10,4) DEFAULT 0;
       DECLARE f FLOAT DEFAULT 0;
       WHILE i < 10000 DO
         SET d = d + .0001;
         SET f = f + .0001E0;
         SET i = i + 1;
       END WHILE;
       SELECT d, f;
     END;

The sum for both `d' and `f' logically should be 1, but that is true
only for the decimal calculation. The floating-point calculation
introduces small errors:

     +--------+------------------+
     | d      | f                |
     +--------+------------------+
     | 1.0000 | 0.99999999999991 |
     +--------+------------------+

*Example 2*. Multiplication is performed with the scale required by
standard SQL. That is, for two numbers X1 and X2 that have scale S1 and
S2, the scale of the result is `S1 + S2':

     mysql> SELECT .01 * .01;
     +-----------+
     | .01 * .01 |
     +-----------+
     | 0.0001    |
     +-----------+

*Example 3*. Rounding behavior is well-defined:

Rounding behavior (for example, with the `ROUND()' function) is
independent of the implementation of the underlying C library, which
means that results are consistent from platform to platform.

Rounding for exact-value columns (`DECIMAL' and integer) and
exact-valued numbers uses the `round half up' rule. Values with a
fractional part of .5 or greater are rounded away from zero to the
nearest integer, as shown here:

     mysql> SELECT ROUND(2.5), ROUND(-2.5);
     +------------+-------------+
     | ROUND(2.5) | ROUND(-2.5) |
     +------------+-------------+
     | 3          | -3          |
     +------------+-------------+

However, rounding for floating-point values uses the C library, which
on many systems uses the `round to nearest even' rule. Values with any
fractional part on such systems are rounded to the nearest even integer:

     mysql> SELECT ROUND(2.5E0), ROUND(-2.5E0);
     +--------------+---------------+
     | ROUND(2.5E0) | ROUND(-2.5E0) |
     +--------------+---------------+
     |            2 |            -2 |
     +--------------+---------------+

*Example 4*. In strict mode, inserting a value that is too large
results in overflow and causes an error, rather than truncation to a
legal value.

When MySQL is not running in strict mode, truncation to a legal value
occurs:

     mysql> SET sql_mode='';
     Query OK, 0 rows affected (0.00 sec)

     mysql> CREATE TABLE t (i TINYINT);
     Query OK, 0 rows affected (0.01 sec)

     mysql> INSERT INTO t SET i = 128;
     Query OK, 1 row affected, 1 warning (0.00 sec)

     mysql> SELECT i FROM t;
     +------+
     | i    |
     +------+
     |  127 |
     +------+
     1 row in set (0.00 sec)

Howver, an overflow condition occurs if strict mode is in effect:

     mysql> SET sql_mode='STRICT_ALL_TABLES';
     Query OK, 0 rows affected (0.00 sec)

     mysql> CREATE TABLE t (i TINYINT);
     Query OK, 0 rows affected (0.00 sec)

     mysql> INSERT INTO t SET i = 128;
     ERROR 1264 (22003): Out of range value adjusted for column 'i' at row 1

     mysql> SELECT i FROM t;
     Empty set (0.00 sec)

*Example 5*: In strict mode and with `ERROR_FOR_DIVISION_BY_ZERO' set,
division by zero causes an error, and not a result of `NULL'.

In non-strict mode, division by zero has a result of `NULL':

     mysql> SET sql_mode='';
     Query OK, 0 rows affected (0.01 sec)

     mysql> CREATE TABLE t (i TINYINT);
     Query OK, 0 rows affected (0.00 sec)

     mysql> INSERT INTO t SET i = 1 / 0;
     Query OK, 1 row affected (0.00 sec)

     mysql> SELECT i FROM t;
     +------+
     | i    |
     +------+
     | NULL |
     +------+
     1 row in set (0.03 sec)

However, division by zero is an error if the proper SQL modes are in
effect:

     mysql> SET sql_mode='STRICT_ALL_TABLES,ERROR_FOR_DIVISION_BY_ZERO';
     Query OK, 0 rows affected (0.00 sec)

     mysql> CREATE TABLE t (i TINYINT);
     Query OK, 0 rows affected (0.00 sec)

     mysql> INSERT INTO t SET i = 1 / 0;
     ERROR 1365 (22012): Division by 0

     mysql> SELECT i FROM t;
     Empty set (0.01 sec)

*Example 6*. Prior to MySQL 5.0.3 (before precision math was
introduced), exact-value and approximate-value literals both are
converted to double-precision floating-point values:

     mysql> SELECT VERSION();
     +------------+
     | VERSION()  |
     +------------+
     | 4.1.18-log |
     +------------+
     1 row in set (0.01 sec)

     mysql> CREATE TABLE t SELECT 2.5 AS a, 25E-1 AS b;
     Query OK, 1 row affected (0.07 sec)
     Records: 1  Duplicates: 0  Warnings: 0

     mysql> DESCRIBE t;
     +-------+-------------+------+-----+---------+-------+
     | Field | Type        | Null | Key | Default | Extra |
     +-------+-------------+------+-----+---------+-------+
     | a     | double(3,1) |      |     | 0.0     |       |
     | b     | double      |      |     | 0       |       |
     +-------+-------------+------+-----+---------+-------+
     2 rows in set (0.04 sec)

As of MySQL 5.0.3, the approximate-value literal still is converted to
floating-point, but the exact-value literal is handled as `DECIMAL':

     mysql> SELECT VERSION();
     +-----------------+
     | VERSION()       |
     +-----------------+
     | 5.1.6-alpha-log |
     +-----------------+
     1 row in set (0.11 sec)

     mysql> CREATE TABLE t SELECT 2.5 AS a, 25E-1 AS b;
     Query OK, 1 row affected (0.01 sec)
     Records: 1  Duplicates: 0  Warnings: 0

     mysql> DESCRIBE t;
     +-------+-----------------------+------+-----+---------+-------+
     | Field | Type                  | Null | Key | Default | Extra |
     +-------+-----------------------+------+-----+---------+-------+
     | a     | decimal(2,1) unsigned | NO   |     | 0.0     |       |
     | b     | double                | NO   |     | 0       |       |
     +-------+-----------------------+------+-----+---------+-------+
     2 rows in set (0.01 sec)

*Example 7*. If the argument to an aggregate function is an exact
numeric type, the result is also an exact numeric type, with a scale at
least that of the argument.

Consider these statements:

     mysql> CREATE TABLE t (i INT, d DECIMAL, f FLOAT);
     mysql> INSERT INTO t VALUES(1,1,1);
     mysql> CREATE TABLE y SELECT AVG(i), AVG(d), AVG(f) FROM t;

Result before MySQL 5.0.3 (prior to the introduction of precision math
in MySQL):

     mysql> DESCRIBE y;
     +--------+--------------+------+-----+---------+-------+
     | Field  | Type         | Null | Key | Default | Extra |
     +--------+--------------+------+-----+---------+-------+
     | AVG(i) | double(17,4) | YES  |     | NULL    |       |
     | AVG(d) | double(17,4) | YES  |     | NULL    |       |
     | AVG(f) | double       | YES  |     | NULL    |       |
     +--------+--------------+------+-----+---------+-------+

The result is a double no matter the argument type.

Result as of MySQL 5.0.3:

     mysql> DESCRIBE y;
     +--------+---------------+------+-----+---------+-------+
     | Field  | Type          | Null | Key | Default | Extra |
     +--------+---------------+------+-----+---------+-------+
     | AVG(i) | decimal(14,4) | YES  |     | NULL    |       |
     | AVG(d) | decimal(14,4) | YES  |     | NULL    |       |
     | AVG(f) | double        | YES  |     | NULL    |       |
     +--------+---------------+------+-----+---------+-------+

The result is a double only for the floating-point argument. For exact
type arguments, the result is also an exact type.


File: manual.info,  Node: apis,  Next: connectors,  Prev: precision-math,  Up: Top

29 APIs and Libraries
*********************

* Menu:

* libmysqld::                    libmysqld, the Embedded MySQL Server Library
* c::                            MySQL C API
* php::                          MySQL PHP API
* perl::                         MySQL Perl API
* cplusplus::                    MySQL C++ API
* python::                       MySQL Python API
* tcl::                          MySQL Tcl API
* eiffel::                       MySQL Eiffel Wrapper

This chapter describes the APIs available for MySQL, where to get them,
and how to use them. The C API is the most extensively covered, because
it was developed by the MySQL team, and is the basis for most of the
other APIs. This chapter also covers the `libmysqld' library (the
embedded server).


File: manual.info,  Node: libmysqld,  Next: c,  Prev: apis,  Up: apis

29.1 libmysqld, the Embedded MySQL Server Library
=================================================

* Menu:

* libmysqld-compiling::          Compiling Programs with `libmysqld'
* libmysqld-restrictions::       Restrictions When Using the Embedded MySQL Server
* libmysqld-options::            Options with the Embedded Server
* libmysqld-example::            Embedded Server Examples
* libmysqld-licensing::          Licensing the Embedded Server

The embedded MySQL server library makes it possible to run a
full-featured MySQL server inside a client application. The main
benefits are increased speed and more simple management for embedded
applications.

The embedded server library is based on the client/server version of
MySQL, which is written in C/C++. Consequently, the embedded server
also is written in C/C++. There is no embedded server available in
other languages.

The API is identical for the embedded MySQL version and the
client/server version. To change an old threaded application to use the
embedded library, you normally only have to add calls to the following
functions:

*Function*         *When to Call*
*Note              Should be called before any other MySQL function
`mysql_library_init()':is called, preferably early in the `main()'
mysql-library-init.function.
*Note              Should be called before your program exits.
`mysql_library_end()':
mysql-library-end. 
*Note              Should be called in each thread you create that
`mysql_thread_init()':accesses MySQL.
mysql-thread-init. 
*Note              Should be called before calling `pthread_exit()'
`mysql_thread_end()':
mysql-thread-end.  

Then you must link your code with `libmysqld.a' instead of
`libmysqlclient.a'. To ensure binary compatibility between your
application and the server library, be sure to compile your application
against headers for the same series of MySQL that was used to compile
the server library. For example, if `libmysqld' was compiled against
MySQL 4.1 headers, do not compile your application against MySQL 5.1
headers, or vice versa.

The `mysql_library_XXX()' functions are also included in
`libmysqlclient.a' to allow you to change between the embedded and the
client/server version by just linking your application with the right
library. See *Note mysql-library-init::.

One difference between the embedded server and the standalone server is
that for the embedded server, authentication for connections is
disabled by default. To use authentication for the embedded server,
specify the `--with-embedded-privilege-control' option when you invoke
`configure' to configure your MySQL distribution.


File: manual.info,  Node: libmysqld-compiling,  Next: libmysqld-restrictions,  Prev: libmysqld,  Up: libmysqld

29.1.1 Compiling Programs with `libmysqld'
------------------------------------------

In precompiled binary MySQL distributions that include `libmysqld', the
embedded server library, MySQL builds the library using the appropriate
vendor compiler if there is one.

To get a `libmysqld' library if you build MySQL from source yourself,
you should configure MySQL with the `--with-embedded-server' option. See
*Note configure-options::.

When you link your program with `libmysqld', you must also include the
system-specific `pthread' libraries and some libraries that the MySQL
server uses. You can get the full list of libraries by executing
`mysql_config --libmysqld-libs'.

The correct flags for compiling and linking a threaded program must be
used, even if you do not directly call any thread functions in your
code.

To compile a C program to include the necessary files to embed the
MySQL server library into an executable version of a program, the
compiler will need to know where to find various files and need
instructions on how to compile the program. The following example shows
how a program could be compiled from the command line, assuming that
you are using `gcc', use the GNU C compiler:

     gcc mysql_test.c -o mysql_test -lz \
     `/usr/local/mysql/bin/mysql_config --include --libmysqld-libs`

Immediately following the `gcc' command is the name of the C program
source file. After it, the `-o' option is given to indicate that the
file name that follows is the name that the compiler is to give to the
output file, the compiled program. The next line of code tells the
compiler to obtain the location of the include files and libraries and
other settings for the system on which it's compiled. Because of a
problem with `mysql_config', the option `-lz' (for compression) is
added here. The `mysql_config' command is contained in backticks, not
single quotes.

On some non-`gcc' platforms, the embedded library depends on C++
runtime libraries and linking against the embedded library might result
in missing-symbol errors. To solve this, link using a C++ compiler or
explicitly list the required libraries on the link command line.


File: manual.info,  Node: libmysqld-restrictions,  Next: libmysqld-options,  Prev: libmysqld-compiling,  Up: libmysqld

29.1.2 Restrictions When Using the Embedded MySQL Server
--------------------------------------------------------

The embedded server has the following limitations:

   * No user-defined functions (UDFs).

   * No stack trace on core dump.

   * You cannot set this up as a master or a slave (no replication).

   * Very large result sets may be unusable on low memory systems.

   * You cannot connect to an embedded server from an outside process
     with sockets or TCP/IP. However, you can connect to an
     intermediate application, which in turn can connect to an embedded
     server on the behalf of a remote client or outside process.

   * `InnoDB' is not reentrant in the embedded server and cannot be
     used for multiple connections, either successively or
     simultaneously.

   * The Event Scheduler is not available. Because of this, the
     `event_scheduler' system variable is disabled.

Some of these limitations can be changed by editing the `mysql_embed.h'
include file and recompiling MySQL.


File: manual.info,  Node: libmysqld-options,  Next: libmysqld-example,  Prev: libmysqld-restrictions,  Up: libmysqld

29.1.3 Options with the Embedded Server
---------------------------------------

Any options that may be given with the `mysqld' server daemon, may be
used with an embedded server library. Server options may be given in an
array as an argument to the *Note `mysql_library_init()':
mysql-library-init, which initializes the server. They also may be
given in an option file like `my.cnf'. To specify an option file for a
C program, use the `--defaults-file' option as one of the elements of
the second argument of the *Note `mysql_library_init()':
mysql-library-init. function.  See *Note mysql-library-init::, for more
information on the *Note `mysql_library_init()': mysql-library-init.
function.

Using option files can make it easier to switch between a client/server
application and one where MySQL is embedded. Put common options under
the `[server]' group. These are read by both MySQL versions.
Client/server-specific options should go under the `[mysqld]' section.
Put options specific to the embedded MySQL server library in the
`[embedded]' section. Options specific to applications go under section
labeled `[ApplicationName_SERVER]'. See *Note option-files::.


File: manual.info,  Node: libmysqld-example,  Next: libmysqld-licensing,  Prev: libmysqld-options,  Up: libmysqld

29.1.4 Embedded Server Examples
-------------------------------

These two example programs should work without any changes on a Linux
or FreeBSD system. For other operating systems, minor changes are
needed, mostly with file paths. These examples are designed to give
enough details for you to understand the problem, without the clutter
that is a necessary part of a real application. The first example is
very straightforward. The second example is a little more advanced with
some error checking. The first is followed by a command-line entry for
compiling the program. The second is followed by a GNUmake file that
may be used for compiling instead.

*Example 1*

`test1_libmysqld.c'

     #include <stdio.h>
     #include <stdlib.h>
     #include <stdarg.h>
     #include "mysql.h"

     MYSQL *mysql;
     MYSQL_RES *results;
     MYSQL_ROW record;

     static char *server_options[] = \
            { "mysql_test", "--defaults-file=my.cnf", NULL };
     int num_elements = (sizeof(server_options) / sizeof(char *)) - 1;

     static char *server_groups[] = { "libmysqld_server",
                                      "libmysqld_client", NULL };

     int main(void)
     {
        mysql_library_init(num_elements, server_options, server_groups);
        mysql = mysql_init(NULL);
        mysql_options(mysql, MYSQL_READ_DEFAULT_GROUP, "libmysqld_client");
        mysql_options(mysql, MYSQL_OPT_USE_EMBEDDED_CONNECTION, NULL);

        mysql_real_connect(mysql, NULL,NULL,NULL, "database1", 0,NULL,0);

        mysql_query(mysql, "SELECT column1, column2 FROM table1");

        results = mysql_store_result(mysql);

        while((record = mysql_fetch_row(results))) {
           printf("%s - %s \n", record[0], record[1]);
        }

        mysql_free_result(results);
        mysql_close(mysql);
        mysql_library_end();

        return 0;
     }

Here is the command line for compiling the above program:

     gcc test1_libmysqld.c -o test1_libmysqld -lz \
      `/usr/local/mysql/bin/mysql_config --include --libmysqld-libs`

*Example 2*

To try out the example, create an `test2_libmysqld' directory at the
same level as the MySQL source directory. Save the `test2_libmysqld.c'
source and the `GNUmakefile' in the directory, and run GNU `make' from
inside the `test2_libmysqld' directory.

`test2_libmysqld.c'

     /*
      * A simple example client, using the embedded MySQL server library
     */

     #include <mysql.h>
     #include <stdarg.h>
     #include <stdio.h>
     #include <stdlib.h>

     MYSQL *db_connect(const char *dbname);
     void db_disconnect(MYSQL *db);
     void db_do_query(MYSQL *db, const char *query);

     const char *server_groups[] = {
       "test2_libmysqld_SERVER", "embedded", "server", NULL
     };

     int
     main(int argc, char **argv)
     {
       MYSQL *one, *two;

       /* mysql_library_init() must be called before any other mysql
        * functions.
        *
        * You can use mysql_library_init(0, NULL, NULL), and it
        * initializes the server using groups = {
        *   "server", "embedded", NULL
        *  }.
        *
        * In your $HOME/.my.cnf file, you probably want to put:

     [test2_libmysqld_SERVER]
     language = /path/to/source/of/mysql/sql/share/english

        * You could, of course, modify argc and argv before passing
        * them to this function.  Or you could create new ones in any
        * way you like.  But all of the arguments in argv (except for
        * argv[0], which is the program name) should be valid options
        * for the MySQL server.
        *
        * If you link this client against the normal mysqlclient
        * library, this function is just a stub that does nothing.
        */
       mysql_library_init(argc, argv, (char **)server_groups);

       one = db_connect("test");
       two = db_connect(NULL);

       db_do_query(one, "SHOW TABLE STATUS");
       db_do_query(two, "SHOW DATABASES");

       mysql_close(two);
       mysql_close(one);

       /* This must be called after all other mysql functions */
       mysql_library_end();

       exit(EXIT_SUCCESS);
     }

     static void
     die(MYSQL *db, char *fmt, ...)
     {
       va_list ap;
       va_start(ap, fmt);
       vfprintf(stderr, fmt, ap);
       va_end(ap);
       (void)putc('\n', stderr);
       if (db)
         db_disconnect(db);
       exit(EXIT_FAILURE);
     }

     MYSQL *
     db_connect(const char *dbname)
     {
       MYSQL *db = mysql_init(NULL);
       if (!db)
         die(db, "mysql_init failed: no memory");
       /*
        * Notice that the client and server use separate group names.
        * This is critical, because the server does not accept the
        * client's options, and vice versa.
        */
       mysql_options(db, MYSQL_READ_DEFAULT_GROUP, "test2_libmysqld_CLIENT");
       if (!mysql_real_connect(db, NULL, NULL, NULL, dbname, 0, NULL, 0))
         die(db, "mysql_real_connect failed: %s", mysql_error(db));

       return db;
     }

     void
     db_disconnect(MYSQL *db)
     {
       mysql_close(db);
     }

     void
     db_do_query(MYSQL *db, const char *query)
     {
       if (mysql_query(db, query) != 0)
         goto err;

       if (mysql_field_count(db) > 0)
       {
         MYSQL_RES   *res;
         MYSQL_ROW    row, end_row;
         int num_fields;

         if (!(res = mysql_store_result(db)))
           goto err;
         num_fields = mysql_num_fields(res);
         while ((row = mysql_fetch_row(res)))
         {
           (void)fputs(">> ", stdout);
           for (end_row = row + num_fields; row < end_row; ++row)
             (void)printf("%s\t", row ? (char*)*row : "NULL");
           (void)fputc('\n', stdout);
         }
         (void)fputc('\n', stdout);
         mysql_free_result(res);
       }
       else
         (void)printf("Affected rows: %lld\n", mysql_affected_rows(db));

       return;

     err:
       die(db, "db_do_query failed: %s [%s]", mysql_error(db), query);
     }

`GNUmakefile'

     # This assumes the MySQL software is installed in /usr/local/mysql
     inc      := /usr/local/mysql/include/mysql
     lib      := /usr/local/mysql/lib

     # If you have not installed the MySQL software yet, try this instead
     #inc      := $(HOME)/mysql-5.1/include
     #lib      := $(HOME)/mysql-5.1/libmysqld

     CC       := gcc
     CPPFLAGS := -I$(inc) -D_THREAD_SAFE -D_REENTRANT
     CFLAGS   := -g -W -Wall
     LDFLAGS  := -static
     # You can change -lmysqld to -lmysqlclient to use the
     # client/server library
     LDLIBS    = -L$(lib) -lmysqld -lz -lm -ldl -lcrypt

     ifneq (,$(shell grep FreeBSD /COPYRIGHT 2>/dev/null))
     # FreeBSD
     LDFLAGS += -pthread
     else
     # Assume Linux
     LDLIBS += -lpthread
     endif

     # This works for simple one-file test programs
     sources := $(wildcard *.c)
     objects := $(patsubst %c,%o,$(sources))
     targets := $(basename $(sources))

     all: $(targets)

     clean:
             rm -f $(targets) $(objects) *.core


File: manual.info,  Node: libmysqld-licensing,  Prev: libmysqld-example,  Up: libmysqld

29.1.5 Licensing the Embedded Server
------------------------------------

We encourage everyone to promote free software by releasing code under
the GPL or a compatible license. For those who are not able to do this,
another option is to purchase a commercial license for the MySQL code
from MySQL AB. For details, please see
`http://www.mysql.com/company/legal/licensing/'.


File: manual.info,  Node: c,  Next: php,  Prev: libmysqld,  Up: apis

29.2 MySQL C API
================

* Menu:

* c-api-datatypes::              C API Data Types
* c-api-function-overview::      C API Function Overview
* c-api-functions::              C API Function Descriptions
* c-api-prepared-statements::    C API Prepared Statements
* c-api-prepared-statement-datatypes::  C API Prepared Statement Data types
* c-api-prepared-statement-function-overview::  C API Prepared Statement Function Overview
* c-api-prepared-statement-functions::  C API Prepared Statement Function Descriptions
* c-api-prepared-statement-problems::  C API Prepared Statement Problems
* c-api-multiple-queries::       C API Handling of Multiple Statement Execution
* c-api-date-handling::          C API Handling of Date and Time Values
* c-thread-functions::           C API Threaded Function Descriptions
* c-embedded-server-func::       C API Embedded Server Function Descriptions
* auto-reconnect::               Controlling Automatic Reconnect Behavior
* c-api-problems::               Common Questions and Problems When Using the C API
* building-clients::             Building Client Programs
* threaded-clients::             How to Make a Threaded Client

The C API code is distributed with MySQL. It is included in the
`mysqlclient' library and allows C programs to access a database.

Many of the clients in the MySQL source distribution are written in C.
If you are looking for examples that demonstrate how to use the C API,
take a look at these clients. You can find these in the `clients'
directory in the MySQL source distribution.

Most of the other client APIs (all except Connector/J and
Connector/NET) use the `mysqlclient' library to communicate with the
MySQL server. This means that, for example, you can take advantage of
many of the same environment variables that are used by other client
programs, because they are referenced from the library. See *Note
programs::, for a list of these variables.

The client has a maximum communication buffer size. The size of the
buffer that is allocated initially (16KB) is automatically increased up
to the maximum size (the maximum is 16MB). Because buffer sizes are
increased only as demand warrants, simply increasing the default
maximum limit does not in itself cause more resources to be used.  This
size check is mostly a check for erroneous statements and communication
packets.

The communication buffer must be large enough to contain a single SQL
statement (for client-to-server traffic) and one row of returned data
(for server-to-client traffic). Each thread's communication buffer is
dynamically enlarged to handle any query or row up to the maximum
limit. For example, if you have `BLOB' values that contain up to 16MB
of data, you must have a communication buffer limit of at least 16MB
(in both server and client). The client's default maximum is 16MB, but
the default maximum in the server is 1MB. You can increase this by
changing the value of the `max_allowed_packet' parameter when the
server is started. See *Note server-parameters::.

The MySQL server shrinks each communication buffer to
`net_buffer_length' bytes after each query. For clients, the size of
the buffer associated with a connection is not decreased until the
connection is closed, at which time client memory is reclaimed.

For programming with threads, see *Note threaded-clients::. For
creating a standalone application which includes the "server" and
"client" in the same program (and does not communicate with an external
MySQL server), see *Note libmysqld::.

MySQL Enterprise

MySQL Enterprise subscribers will find more information about using the
C API in the Knowledge Base articles, The C API
(https://kb.mysql.com/search.php?cat=search&pagerRow=0&Category=17).
Access to the MySQL Knowledge Base collection of articles is one of the
advantages of subscribing to MySQL Enterprise. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: c-api-datatypes,  Next: c-api-function-overview,  Prev: c,  Up: c

29.2.1 C API Data Types
-----------------------

This section describes C API data types other than those used for
prepared statements. For information about the latter, see *Note
c-api-prepared-statement-datatypes::.

   * `MYSQL'

     This structure represents a handle to one database connection.  It
     is used for almost all MySQL functions. You should not try to make
     a copy of a `MYSQL' structure. There is no guarantee that such a
     copy will be usable.

   * `MYSQL_RES'

     This structure represents the result of a query that returns rows
     (`SELECT', `SHOW', `DESCRIBE', `EXPLAIN'). The information
     returned from a query is called the _result set_ in the remainder
     of this section.

   * `MYSQL_ROW'

     This is a type-safe representation of one row of data. It is
     currently implemented as an array of counted byte strings.  (You
     cannot treat these as null-terminated strings if field values may
     contain binary data, because such values may contain null bytes
     internally.) Rows are obtained by calling *Note
     `mysql_fetch_row()': mysql-fetch-row.

   * `MYSQL_FIELD'

     This structure contains information about a field, such as the
     field's name, type, and size. Its members are described in more
     detail here. You may obtain the `MYSQL_FIELD' structures for each
     field by calling *Note `mysql_fetch_field()': mysql-fetch-field.
     repeatedly. Field values are not part of this structure; they are
     contained in a `MYSQL_ROW' structure.

   * `MYSQL_FIELD_OFFSET'

     This is a type-safe representation of an offset into a MySQL field
     list. (Used by *Note `mysql_field_seek()': mysql-field-seek.)
     Offsets are field numbers within a row, beginning at zero.

   * `my_ulonglong'

     The type used for the number of rows and for *Note
     `mysql_affected_rows()': mysql-affected-rows, *Note
     `mysql_num_rows()': mysql-num-rows, and *Note `mysql_insert_id()':
     mysql-insert-id. This type provides a range of `0' to `1.84e19'.

     On some systems, attempting to print a value of type
     `my_ulonglong' does not work. To print such a value, convert it to
     `unsigned long' and use a `%lu' print format. Example:

          printf ("Number of rows: %lu\n",
                  (unsigned long) mysql_num_rows(result));

   * `my_bool'

     A boolean type, for values that are true (non-zero) or false
     (zero).

The `MYSQL_FIELD' structure contains the members listed here:

   * `char * name'

     The name of the field, as a null-terminated string. If the field
     was given an alias with an `AS' clause, the value of `name' is the
     alias.

   * `char * org_name'

     The name of the field, as a null-terminated string. Aliases are
     ignored.

   * `char * table'

     The name of the table containing this field, if it isn't a
     calculated field. For calculated fields, the `table' value is an
     empty string. If the column is selected from a view, `table' names
     the view. If the table or view was given an alias with an `AS'
     clause, the value of `table' is the alias. For a `UNION', the
     value is the empty string.

   * `char * org_table'

     The name of the table, as a null-terminated string. Aliases are
     ignored. If the column is selected from a view, `org_table' names
     the underlying table. For a `UNION', the value is the empty string.

   * `char * db'

     The name of the database that the field comes from, as a
     null-terminated string. If the field is a calculated field, `db'
     is an empty string. For a `UNION', the value is the empty string.

   * `char * catalog'

     The catalog name. This value is always `"def"'.

   * `char * def'

     The default value of this field, as a null-terminated string.
     This is set only if you use *Note `mysql_list_fields()':
     mysql-list-fields.

   * `unsigned long length'

     The width of the field. This corresponds to the display length, in
     bytes.

   * `unsigned long max_length'

     The maximum width of the field for the result set (the length in
     bytes of the longest field value for the rows actually in the
     result set). If you use *Note `mysql_store_result()':
     mysql-store-result. or *Note `mysql_list_fields()':
     mysql-list-fields, this contains the maximum length for the field.
     If you use *Note `mysql_use_result()': mysql-use-result, the value
     of this variable is zero.

     The value of `max_length' is the length of the string
     representation of the values in the result set. For example, if
     you retrieve a `FLOAT' column and the `widest' value is `-12.345',
     `max_length' is 7 (the length of `'-12.345'').

     If you are using prepared statements, `max_length' is not set by
     default because for the binary protocol the lengths of the values
     depend on the types of the values in the result set. (See *Note
     c-api-prepared-statement-datatypes::.) If you want the
     `max_length' values anyway, enable the
     `STMT_ATTR_UPDATE_MAX_LENGTH' option with *Note
     `mysql_stmt_attr_set()': mysql-stmt-attr-set. and the lengths will
     be set when you call *Note `mysql_stmt_store_result()':
     mysql-stmt-store-result.  (See *Note mysql-stmt-attr-set::, and
     *Note mysql-stmt-store-result::.)

   * `unsigned int name_length'

     The length of `name'.

   * `unsigned int org_name_length'

     The length of `org_name'.

   * `unsigned int table_length'

     The length of `table'.

   * `unsigned int org_table_length'

     The length of `org_table'.

   * `unsigned int db_length'

     The length of `db'.

   * `unsigned int catalog_length'

     The length of `catalog'.

   * `unsigned int def_length'

     The length of `def'.

   * `unsigned int flags'

     Different bit-flags for the field. The `flags' value may have zero
     or more of the following bits set:

     *Flag Value*                *Flag Description*
     `NOT_NULL_FLAG'             Field can't be `NULL'
     `PRI_KEY_FLAG'              Field is part of a primary key
     `UNIQUE_KEY_FLAG'           Field is part of a unique key
     `MULTIPLE_KEY_FLAG'         Field is part of a non-unique key
     `UNSIGNED_FLAG'             Field has the `UNSIGNED' attribute
     `ZEROFILL_FLAG'             Field has the `ZEROFILL' attribute
     `BINARY_FLAG'               Field has the `BINARY' attribute
     `AUTO_INCREMENT_FLAG'       Field has the `AUTO_INCREMENT' attribute
     `ENUM_FLAG'                 Field is an `ENUM' (deprecated)
     `SET_FLAG'                  Field is a `SET' (deprecated)
     `BLOB_FLAG'                 Field is a `BLOB' or `TEXT' (deprecated)
     `TIMESTAMP_FLAG'            Field is a `TIMESTAMP' (deprecated)
     `NO_DEFAULT_VALUE_FLAG'     Field has no default value; see
                                 additional notes following table

     Use of the `BLOB_FLAG', `ENUM_FLAG', `SET_FLAG', and
     `TIMESTAMP_FLAG' flags is deprecated because they indicate the
     type of a field rather than an attribute of its type. It is
     preferable to test `field->type' against `MYSQL_TYPE_BLOB',
     `MYSQL_TYPE_ENUM', `MYSQL_TYPE_SET', or `MYSQL_TYPE_TIMESTAMP'
     instead.

     `NUM_FLAG' indicates that a column is numeric. This includes
     columns with a type of `MYSQL_TYPE_DECIMAL', `MYSQL_TYPE_TINY',
     `MYSQL_TYPE_SHORT', `MYSQL_TYPE_LONG', `MYSQL_TYPE_FLOAT',
     `MYSQL_TYPE_DOUBLE', `MYSQL_TYPE_NULL', `MYSQL_TYPE_TIMESTAMP',
     `MYSQL_TYPE_LONGLONG', `MYSQL_TYPE_INT24', and `MYSQL_TYPE_YEAR'.

     `NO_DEFAULT_VALUE_FLAG' indicates that a column has no `DEFAULT'
     clause in its definition. This does not apply to `NULL' columns
     (because such columns have a default of `NULL'), or to
     `AUTO_INCREMENT' columns (which have an implied default value).

     The following example illustrates a typical use of the `flags'
     value:

          if (field->flags & NOT_NULL_FLAG)
              printf("Field can't be null\n");

     You may use the following convenience macros to determine the
     boolean status of the `flags' value:

     *Flag Status*               *Description*
     `IS_NOT_NULL(flags)'        True if this field is defined as `NOT
                                 NULL'
     `IS_PRI_KEY(flags)'         True if this field is a primary key
     `IS_BLOB(flags)'            True if this field is a `BLOB' or
                                 `TEXT' (deprecated; test `field->type'
                                 instead)

   * `unsigned int decimals'

     The number of decimals for numeric fields.

   * `unsigned int charsetnr'

     An ID number that indicates the character set/collation pair for
     the field.

     To distinguish between binary and non-binary data for string data
     types, check whether the `charsetnr' value is 63. If so, the
     character set is `binary', which indicates binary rather than
     non-binary data. This enables you to distinguish `BINARY' from
     `CHAR', `VARBINARY' from `VARCHAR', and the `BLOB' types from the
     `TEXT' types.

     `charsetnr' values are the same as those displayed in the `Id'
     column of the `SHOW COLLATION' statement or the `ID' column of the
     `INFORMATION_SCHEMA' `COLLATIONS' table. You can use those
     information sources to see which character set and collation
     specific `charsetnr' values indicate:

          mysql> SHOW COLLATION WHERE Id = 63;
          +-----------+---------+----+---------+----------+---------+
          | Collation | Charset | Id | Default | Compiled | Sortlen |
          +-----------+---------+----+---------+----------+---------+
          | binary    | binary  | 63 | Yes     | Yes      |       1 |
          +-----------+---------+----+---------+----------+---------+

          mysql> SELECT COLLATION_NAME, CHARACTER_SET_NAME
              -> FROM INFORMATION_SCHEMA.COLLATIONS WHERE ID = 33;
          +-----------------+--------------------+
          | COLLATION_NAME  | CHARACTER_SET_NAME |
          +-----------------+--------------------+
          | utf8_general_ci | utf8               |
          +-----------------+--------------------+

   * `enum enum_field_types type'

     The type of the field. The `type' value may be one of the
     `MYSQL_TYPE_' symbols shown in the following table.

     *Type Value*            *Type Description*
     `MYSQL_TYPE_TINY'       `TINYINT' field
     `MYSQL_TYPE_SHORT'      `SMALLINT' field
     `MYSQL_TYPE_LONG'       `INTEGER' field
     `MYSQL_TYPE_INT24'      `MEDIUMINT' field
     `MYSQL_TYPE_LONGLONG'   `BIGINT' field
     `MYSQL_TYPE_DECIMAL'    `DECIMAL' or `NUMERIC' field
     `MYSQL_TYPE_NEWDECIMAL' Precision math `DECIMAL' or `NUMERIC'
     `MYSQL_TYPE_FLOAT'      `FLOAT' field
     `MYSQL_TYPE_DOUBLE'     `DOUBLE' or `REAL' field
     `MYSQL_TYPE_BIT'        `BIT' field
     `MYSQL_TYPE_TIMESTAMP'  `TIMESTAMP' field
     `MYSQL_TYPE_DATE'       `DATE' field
     `MYSQL_TYPE_TIME'       `TIME' field
     `MYSQL_TYPE_DATETIME'   `DATETIME' field
     `MYSQL_TYPE_YEAR'       `YEAR' field
     `MYSQL_TYPE_STRING'     `CHAR' or `BINARY' field
     `MYSQL_TYPE_VAR_STRING' `VARCHAR' or `VARBINARY' field
     `MYSQL_TYPE_BLOB'       `BLOB' or `TEXT' field (use `max_length' to
                             determine the maximum length)
     `MYSQL_TYPE_SET'        `SET' field
     `MYSQL_TYPE_ENUM'       `ENUM' field
     `MYSQL_TYPE_GEOMETRY'   Spatial field
     `MYSQL_TYPE_NULL'       `NULL'-type field

     You can use the `IS_NUM()' macro to test whether a field has a
     numeric type. Pass the `type' value to `IS_NUM()' and it evaluates
     to TRUE if the field is numeric:

          if (IS_NUM(field->type))
              printf("Field is numeric\n");


File: manual.info,  Node: c-api-function-overview,  Next: c-api-functions,  Prev: c-api-datatypes,  Up: c

29.2.2 C API Function Overview
------------------------------

The functions available in the C API are summarized here and described
in greater detail in a later section. See *Note c-api-functions::.

*Function*              *Description*
*Note `my_init()':      Initialize global variables, and thread handler
my-init.                in thread-safe programs
*Note                   Returns the number of rows
`mysql_affected_rows()':changed/deleted/inserted by the last `UPDATE',
mysql-affected-rows.    `DELETE', or `INSERT' query
*Note                   Toggles autocommit mode on/off
`mysql_autocommit()':   
mysql-autocommit.       
*Note                   Changes user and database on an open connection
`mysql_change_user()':  
mysql-change-user.      
*Note                   Return default character set name for current
`mysql_character_set_name()':connection
mysql-character-set-name.
*Note `mysql_close()':  Closes a server connection
mysql-close.            
*Note                   Commits the transaction
`mysql_commit()':       
mysql-commit.           
*Note                   Connects to a MySQL server (this function is
`mysql_connect()':      deprecated; use *Note `mysql_real_connect()':
mysql-connect.          mysql-real-connect.  instead)
*Note                   Creates a database (this function is deprecated;
`mysql_create_db()':    use the SQL statement `CREATE DATABASE' instead)
mysql-create-db.        
*Note                   Seeks to an arbitrary row number in a query
`mysql_data_seek()':    result set
mysql-data-seek.        
*Note `mysql_debug()':  Does a `DBUG_PUSH' with the given string
mysql-debug.            
*Note                   Drops a database (this function is deprecated;
`mysql_drop_db()':      use the SQL statement `DROP DATABASE' instead)
mysql-drop-db.          
*Note                   Makes the server write debug information to the
`mysql_dump_debug_info()':log
mysql-dump-debug-info.  
*Note `mysql_eof()':    Determines whether the last row of a result set
mysql-eof.              has been read (this function is deprecated;
                        *Note `mysql_errno()': mysql-errno. or *Note
                        `mysql_error()': mysql-error. may be used
                        instead)
*Note `mysql_errno()':  Returns the error number for the most recently
mysql-errno.            invoked MySQL function
*Note `mysql_error()':  Returns the error message for the most recently
mysql-error.            invoked MySQL function
*Note                   Escapes special characters in a string for use
`mysql_escape_string()':in an SQL statement
mysql-escape-string.    
*Note                   Returns the type of the next table field
`mysql_fetch_field()':  
mysql-fetch-field.      
*Note                   Returns the type of a table field, given a field
`mysql_fetch_field_direct()':number
mysql-fetch-field-direct.
*Note                   Returns an array of all field structures
`mysql_fetch_fields()': 
mysql-fetch-fields.     
*Note                   Returns the lengths of all columns in the
`mysql_fetch_lengths()':current row
mysql-fetch-lengths.    
*Note                   Fetches the next row from the result set
`mysql_fetch_row()':    
mysql-fetch-row.        
*Note                   Returns the number of result columns for the
`mysql_field_count()':  most recent statement
mysql-field-count.      
*Note                   Puts the column cursor on a specified column
`mysql_field_seek()':   
mysql-field-seek.       
*Note                   Returns the position of the field cursor used
`mysql_field_tell()':   for the last *Note `mysql_fetch_field()':
mysql-field-tell.       mysql-fetch-field.
*Note                   Frees memory used by a result set
`mysql_free_result()':  
mysql-free-result.      
*Note                   Return information about default character set
`mysql_get_character_set_info()':
mysql-get-character-set-info.
*Note                   Returns client version information as a string
`mysql_get_client_info()':
mysql-get-client-info.  
*Note                   Returns client version information as an integer
`mysql_get_client_version()':
mysql-get-client-version.
*Note                   Returns a string describing the connection
`mysql_get_host_info()':
mysql-get-host-info.    
*Note                   Returns the protocol version used by the
`mysql_get_proto_info()':connection
mysql-get-proto-info.   
*Note                   Returns the server version number
`mysql_get_server_info()':
mysql-get-server-info.  
*Note                   Returns version number of server as an integer
`mysql_get_server_version()':
mysql-get-server-version.
*Note                   Return current SSL cipher
`mysql_get_ssl_cipher()':
mysql-get-ssl-cipher.   
*Note                   Encode string in hexadecimal format
`mysql_hex_string()':   
mysql-hex-string.       
*Note `mysql_info()':   Returns information about the most recently
mysql-info.             executed query
*Note `mysql_init()':   Gets or initializes a `MYSQL' structure
mysql-init.             
*Note                   Returns the ID generated for an `AUTO_INCREMENT'
`mysql_insert_id()':    column by the previous query
mysql-insert-id.        
*Note `mysql_kill()':   Kills a given thread
mysql-kill.             
*Note                   Finalize the MySQL C API library
`mysql_library_end()':  
mysql-library-end.      
*Note                   Initialize the MySQL C API library
`mysql_library_init()': 
mysql-library-init.     
*Note                   Returns database names matching a simple regular
`mysql_list_dbs()':     expression
mysql-list-dbs.         
*Note                   Returns field names matching a simple regular
`mysql_list_fields()':  expression
mysql-list-fields.      
*Note                   Returns a list of the current server threads
`mysql_list_processes()':
mysql-list-processes.   
*Note                   Returns table names matching a simple regular
`mysql_list_tables()':  expression
mysql-list-tables.      
*Note                   Checks whether any more results exist
`mysql_more_results()': 
mysql-more-results.     
*Note                   Returns/initiates the next result in
`mysql_next_result()':  multiple-statement executions
mysql-next-result.      
*Note                   Returns the number of columns in a result set
`mysql_num_fields()':   
mysql-num-fields.       
*Note                   Returns the number of rows in a result set
`mysql_num_rows()':     
mysql-num-rows.         
*Note                   Sets connect options for *Note
`mysql_options()':      `mysql_real_connect()': mysql-real-connect.
mysql-options.          
*Note `mysql_ping()':   Checks whether the connection to the server is
mysql-ping.             working, reconnecting as necessary
*Note `mysql_query()':  Executes an SQL query specified as a
mysql-query.            null-terminated string
*Note                   Connects to a MySQL server
`mysql_real_connect()': 
mysql-real-connect.     
*Note                   Escapes special characters in a string for use
`mysql_real_escape_string()':in an SQL statement, taking into account the
mysql-real-escape-string.current character set of the connection
*Note                   Executes an SQL query specified as a counted
`mysql_real_query()':   string
mysql-real-query.       
*Note                   Flush or reset tables and caches
`mysql_refresh()':      
mysql-refresh.          
*Note                   Tells the server to reload the grant tables
`mysql_reload()':       
mysql-reload.           
*Note                   Rolls back the transaction
`mysql_rollback()':     
mysql-rollback.         
*Note                   Seeks to a row offset in a result set, using
`mysql_row_seek()':     value returned from *Note `mysql_row_tell()':
mysql-row-seek.         mysql-row-tell.
*Note                   Returns the row cursor position
`mysql_row_tell()':     
mysql-row-tell.         
*Note                   Selects a database
`mysql_select_db()':    
mysql-select-db.        
*Note                   Finalize the MySQL C API library
`mysql_server_end()':   
mysql-server-end.       
*Note                   Initialize the MySQL C API library
`mysql_server_init()':  
mysql-server-init.      
*Note                   Set default character set for current connection
`mysql_set_character_set()':
mysql-set-character-set.
*Note                   Set the `LOAD DATA LOCAL INFILE' handler
`mysql_set_local_infile_default()':callbacks to their default values
mysql-set-local-infile-default.
*Note                   Install application-specific `LOAD DATA LOCAL
`mysql_set_local_infile_handler()':INFILE' handler callbacks
mysql-set-local-infile-handler.
*Note                   Sets an option for the connection (like
`mysql_set_server_option()':`multi-statements')
mysql-set-server-option.
*Note                   Returns the SQLSTATE error code for the last
`mysql_sqlstate()':     error
mysql-sqlstate.         
*Note                   Shuts down the database server
`mysql_shutdown()':     
mysql-shutdown.         
*Note                   Prepare to establish SSL connection to server
`mysql_ssl_set()':      
mysql-ssl-set.          
*Note `mysql_stat()':   Returns the server status as a string
mysql-stat.             
*Note                   Retrieves a complete result set to the client
`mysql_store_result()': 
mysql-store-result.     
*Note                   Finalize thread handler
`mysql_thread_end()':   
mysql-thread-end.       
*Note                   Returns the current thread ID
`mysql_thread_id()':    
mysql-thread-id.        
*Note                   Initialize thread handler
`mysql_thread_init()':  
mysql-thread-init.      
*Note                   Returns 1 if the clients are compiled as
`mysql_thread_safe()':  thread-safe
mysql-thread-safe.      
*Note                   Initiates a row-by-row result set retrieval
`mysql_use_result()':   
mysql-use-result.       
*Note                   Returns the warning count for the previous SQL
`mysql_warning_count()':statement
mysql-warning-count.    

Application programs should use this general outline for interacting
with MySQL:

  1. Initialize the MySQL library by calling *Note
     `mysql_library_init()': mysql-library-init. This function exists
     in both the `mysqlclient' C client library and the `mysqld'
     embedded server library, so it is used whether you build a regular
     client program by linking with the `-libmysqlclient' flag, or an
     embedded server application by linking with the `-libmysqld' flag.

  2. Initialize a connection handler by calling *Note `mysql_init()':
     mysql-init. and connect to the server by calling *Note
     `mysql_real_connect()': mysql-real-connect.

  3. Issue SQL statements and process their results. (The following
     discussion provides more information about how to do this.)

  4. Close the connection to the MySQL server by calling *Note
     `mysql_close()': mysql-close.

  5. End use of the MySQL library by calling *Note
     `mysql_library_end()': mysql-library-end.

The purpose of calling *Note `mysql_library_init()':
mysql-library-init. and *Note `mysql_library_end()': mysql-library-end.
is to provide proper initialization and finalization of the MySQL
library. For applications that are linked with the client library, they
provide improved memory management. If you don't call *Note
`mysql_library_end()': mysql-library-end, a block of memory remains
allocated. (This does not increase the amount of memory used by the
application, but some memory leak detectors will complain about it.)
For applications that are linked with the embedded server, these calls
start and stop the server.

In a non-multi-threaded environment, the call to *Note
`mysql_library_init()': mysql-library-init. may be omitted, because
*Note `mysql_init()': mysql-init.  will invoke it automatically as
necessary. However, *Note `mysql_library_init()': mysql-library-init.
is not thread-safe in a multi-threaded environment, and thus neither is
*Note `mysql_init()': mysql-init, which calls *Note
`mysql_library_init()': mysql-library-init. You must either call *Note
`mysql_library_init()': mysql-library-init.  prior to spawning any
threads, or else use a mutex to protect the call, whether you invoke
*Note `mysql_library_init()': mysql-library-init. or indirectly via
*Note `mysql_init()': mysql-init. This should be done prior to any
other client library call.

To connect to the server, call *Note `mysql_init()': mysql-init. to
initialize a connection handler, then call *Note
`mysql_real_connect()': mysql-real-connect. with that handler (along
with other information such as the hostname, username, and password).
Upon connection, *Note `mysql_real_connect()': mysql-real-connect. sets
the `reconnect' flag (part of the `MYSQL' structure) to a value of `1'
in versions of the API older than 5.0.3, or `0' in newer versions. A
value of `1' for this flag indicates that if a statement cannot be
performed because of a lost connection, to try reconnecting to the
server before giving up. You can use the `MYSQL_OPT_RECONNECT' option to
*Note `mysql_options()': mysql-options. to control reconnection
behavior. When you are done with the connection, call *Note
`mysql_close()': mysql-close. to terminate it.

While a connection is active, the client may send SQL statements to the
server using *Note `mysql_query()': mysql-query.  or *Note
`mysql_real_query()': mysql-real-query. The difference between the two
is that *Note `mysql_query()': mysql-query. expects the query to be
specified as a null-terminated string whereas *Note
`mysql_real_query()': mysql-real-query. expects a counted string. If
the string contains binary data (which may include null bytes), you
must use *Note `mysql_real_query()': mysql-real-query.

For each non-`SELECT' query (for example, `INSERT', `UPDATE',
`DELETE'), you can find out how many rows were changed (affected) by
calling *Note `mysql_affected_rows()': mysql-affected-rows.

For `SELECT' queries, you retrieve the selected rows as a result set.
(Note that some statements are `SELECT'-like in that they return rows.
These include `SHOW', `DESCRIBE', and `EXPLAIN'. They should be treated
the same way as `SELECT' statements.)

There are two ways for a client to process result sets. One way is to
retrieve the entire result set all at once by calling *Note
`mysql_store_result()': mysql-store-result. This function acquires from
the server all the rows returned by the query and stores them in the
client. The second way is for the client to initiate a row-by-row
result set retrieval by calling *Note `mysql_use_result()':
mysql-use-result. This function initializes the retrieval, but does not
actually get any rows from the server.

In both cases, you access rows by calling *Note `mysql_fetch_row()':
mysql-fetch-row. With *Note `mysql_store_result()': mysql-store-result,
*Note `mysql_fetch_row()': mysql-fetch-row. accesses rows that have
previously been fetched from the server. With *Note
`mysql_use_result()': mysql-use-result, *Note `mysql_fetch_row()':
mysql-fetch-row. actually retrieves the row from the server.
Information about the size of the data in each row is available by
calling *Note `mysql_fetch_lengths()': mysql-fetch-lengths.

After you are done with a result set, call *Note `mysql_free_result()':
mysql-free-result. to free the memory used for it.

The two retrieval mechanisms are complementary. Client programs should
choose the approach that is most appropriate for their requirements. In
practice, clients tend to use *Note `mysql_store_result()':
mysql-store-result. more commonly.

An advantage of *Note `mysql_store_result()': mysql-store-result. is
that because the rows have all been fetched to the client, you not only
can access rows sequentially, you can move back and forth in the result
set using *Note `mysql_data_seek()': mysql-data-seek. or *Note
`mysql_row_seek()': mysql-row-seek. to change the current row position
within the result set. You can also find out how many rows there are by
calling *Note `mysql_num_rows()': mysql-num-rows. On the other hand,
the memory requirements for *Note `mysql_store_result()':
mysql-store-result. may be very high for large result sets and you are
more likely to encounter out-of-memory conditions.

An advantage of *Note `mysql_use_result()': mysql-use-result. is that
the client requires less memory for the result set because it maintains
only one row at a time (and because there is less allocation overhead,
*Note `mysql_use_result()': mysql-use-result. can be faster).
Disadvantages are that you must process each row quickly to avoid tying
up the server, you don't have random access to rows within the result
set (you can only access rows sequentially), and you don't know how
many rows are in the result set until you have retrieved them all.
Furthermore, you *must* retrieve all the rows even if you determine in
mid-retrieval that you've found the information you were looking for.

The API makes it possible for clients to respond appropriately to
statements (retrieving rows only as necessary) without knowing whether
the statement is a `SELECT'. You can do this by calling *Note
`mysql_store_result()': mysql-store-result. after each *Note
`mysql_query()': mysql-query. (or *Note `mysql_real_query()':
mysql-real-query.). If the result set call succeeds, the statement was a
`SELECT' and you can read the rows. If the result set call fails, call
*Note `mysql_field_count()': mysql-field-count. to determine whether a
result was actually to be expected. If *Note `mysql_field_count()':
mysql-field-count. returns zero, the statement returned no data
(indicating that it was an `INSERT', `UPDATE', `DELETE', and so forth),
and was not expected to return rows. If *Note `mysql_field_count()':
mysql-field-count. is non-zero, the statement should have returned
rows, but didn't. This indicates that the statement was a `SELECT' that
failed. See the description for *Note `mysql_field_count()':
mysql-field-count. for an example of how this can be done.

Both *Note `mysql_store_result()': mysql-store-result. and *Note
`mysql_use_result()': mysql-use-result. allow you to obtain information
about the fields that make up the result set (the number of fields,
their names and types, and so forth). You can access field information
sequentially within the row by calling *Note `mysql_fetch_field()':
mysql-fetch-field.  repeatedly, or by field number within the row by
calling *Note `mysql_fetch_field_direct()': mysql-fetch-field-direct.
The current field cursor position may be changed by calling *Note
`mysql_field_seek()': mysql-field-seek. Setting the field cursor
affects subsequent calls to *Note `mysql_fetch_field()':
mysql-fetch-field. You can also get information for fields all at once
by calling *Note `mysql_fetch_fields()': mysql-fetch-fields.

For detecting and reporting errors, MySQL provides access to error
information by means of the *Note `mysql_errno()': mysql-errno. and
*Note `mysql_error()': mysql-error. functions. These return the error
code or error message for the most recently invoked function that can
succeed or fail, allowing you to determine when an error occurred and
what it was.


File: manual.info,  Node: c-api-functions,  Next: c-api-prepared-statements,  Prev: c-api-function-overview,  Up: c

29.2.3 C API Function Descriptions
----------------------------------

* Menu:

* mysql-affected-rows::          *Note `mysql_affected_rows()': mysql-affected-rows.
* mysql-autocommit::             *Note `mysql_autocommit()': mysql-autocommit.
* mysql-change-user::            *Note `mysql_change_user()': mysql-change-user.
* mysql-character-set-name::     *Note `mysql_character_set_name()': mysql-character-set-name.
* mysql-close::                  *Note `mysql_close()': mysql-close.
* mysql-commit::                 *Note `mysql_commit()': mysql-commit.
* mysql-connect::                *Note `mysql_connect()': mysql-connect.
* mysql-create-db::              *Note `mysql_create_db()': mysql-create-db.
* mysql-data-seek::              *Note `mysql_data_seek()': mysql-data-seek.
* mysql-debug::                  *Note `mysql_debug()': mysql-debug.
* mysql-drop-db::                *Note `mysql_drop_db()': mysql-drop-db.
* mysql-dump-debug-info::        *Note `mysql_dump_debug_info()': mysql-dump-debug-info.
* mysql-eof::                    *Note `mysql_eof()': mysql-eof.
* mysql-errno::                  *Note `mysql_errno()': mysql-errno.
* mysql-error::                  *Note `mysql_error()': mysql-error.
* mysql-escape-string::          *Note `mysql_escape_string()': mysql-escape-string.
* mysql-fetch-field::            *Note `mysql_fetch_field()': mysql-fetch-field.
* mysql-fetch-field-direct::     *Note `mysql_fetch_field_direct()': mysql-fetch-field-direct.
* mysql-fetch-fields::           *Note `mysql_fetch_fields()': mysql-fetch-fields.
* mysql-fetch-lengths::          *Note `mysql_fetch_lengths()': mysql-fetch-lengths.
* mysql-fetch-row::              *Note `mysql_fetch_row()': mysql-fetch-row.
* mysql-field-count::            *Note `mysql_field_count()': mysql-field-count.
* mysql-field-seek::             *Note `mysql_field_seek()': mysql-field-seek.
* mysql-field-tell::             *Note `mysql_field_tell()': mysql-field-tell.
* mysql-free-result::            *Note `mysql_free_result()': mysql-free-result.
* mysql-get-character-set-info::  *Note `mysql_get_character_set_info()': mysql-get-character-set-info.
* mysql-get-client-info::        *Note `mysql_get_client_info()': mysql-get-client-info.
* mysql-get-client-version::     *Note `mysql_get_client_version()': mysql-get-client-version.
* mysql-get-host-info::          *Note `mysql_get_host_info()': mysql-get-host-info.
* mysql-get-proto-info::         *Note `mysql_get_proto_info()': mysql-get-proto-info.
* mysql-get-server-info::        *Note `mysql_get_server_info()': mysql-get-server-info.
* mysql-get-server-version::     *Note `mysql_get_server_version()': mysql-get-server-version.
* mysql-get-ssl-cipher::         *Note `mysql_get_ssl_cipher()': mysql-get-ssl-cipher.
* mysql-hex-string::             *Note `mysql_hex_string()': mysql-hex-string.
* mysql-info::                   *Note `mysql_info()': mysql-info.
* mysql-init::                   *Note `mysql_init()': mysql-init.
* mysql-insert-id::              *Note `mysql_insert_id()': mysql-insert-id.
* mysql-kill::                   *Note `mysql_kill()': mysql-kill.
* mysql-library-end::            *Note `mysql_library_end()': mysql-library-end.
* mysql-library-init::           *Note `mysql_library_init()': mysql-library-init.
* mysql-list-dbs::               *Note `mysql_list_dbs()': mysql-list-dbs.
* mysql-list-fields::            *Note `mysql_list_fields()': mysql-list-fields.
* mysql-list-processes::         *Note `mysql_list_processes()': mysql-list-processes.
* mysql-list-tables::            *Note `mysql_list_tables()': mysql-list-tables.
* mysql-more-results::           *Note `mysql_more_results()': mysql-more-results.
* mysql-next-result::            *Note `mysql_next_result()': mysql-next-result.
* mysql-num-fields::             *Note `mysql_num_fields()': mysql-num-fields.
* mysql-num-rows::               *Note `mysql_num_rows()': mysql-num-rows.
* mysql-options::                *Note `mysql_options()': mysql-options.
* mysql-ping::                   *Note `mysql_ping()': mysql-ping.
* mysql-query::                  *Note `mysql_query()': mysql-query.
* mysql-real-connect::           *Note `mysql_real_connect()': mysql-real-connect.
* mysql-real-escape-string::     *Note `mysql_real_escape_string()': mysql-real-escape-string.
* mysql-real-query::             *Note `mysql_real_query()': mysql-real-query.
* mysql-refresh::                *Note `mysql_refresh()': mysql-refresh.
* mysql-reload::                 *Note `mysql_reload()': mysql-reload.
* mysql-rollback::               *Note `mysql_rollback()': mysql-rollback.
* mysql-row-seek::               *Note `mysql_row_seek()': mysql-row-seek.
* mysql-row-tell::               *Note `mysql_row_tell()': mysql-row-tell.
* mysql-select-db::              *Note `mysql_select_db()': mysql-select-db.
* mysql-set-character-set::      *Note `mysql_set_character_set()': mysql-set-character-set.
* mysql-set-local-infile-default::  *Note `mysql_set_local_infile_default()': mysql-set-local-infile-default.
* mysql-set-local-infile-handler::  *Note `mysql_set_local_infile_handler()': mysql-set-local-infile-handler.
* mysql-set-server-option::      *Note `mysql_set_server_option()': mysql-set-server-option.
* mysql-shutdown::               *Note `mysql_shutdown()': mysql-shutdown.
* mysql-sqlstate::               *Note `mysql_sqlstate()': mysql-sqlstate.
* mysql-ssl-set::                *Note `mysql_ssl_set()': mysql-ssl-set.
* mysql-stat::                   *Note `mysql_stat()': mysql-stat.
* mysql-store-result::           *Note `mysql_store_result()': mysql-store-result.
* mysql-thread-id::              *Note `mysql_thread_id()': mysql-thread-id.
* mysql-use-result::             *Note `mysql_use_result()': mysql-use-result.
* mysql-warning-count::          *Note `mysql_warning_count()': mysql-warning-count.

In the descriptions here, a parameter or return value of `NULL' means
`NULL' in the sense of the C programming language, not a MySQL `NULL'
value.

Functions that return a value generally return a pointer or an integer.
Unless specified otherwise, functions returning a pointer return a
non-`NULL' value to indicate success or a `NULL' value to indicate an
error, and functions returning an integer return zero to indicate
success or non-zero to indicate an error. Note that `non-zero' means
just that. Unless the function description says otherwise, do not test
against a value other than zero:

     if (result)                   /* correct */
         ... error ...

     if (result < 0)               /* incorrect */
         ... error ...

     if (result == -1)             /* incorrect */
         ... error ...

When a function returns an error, the *Errors* subsection of the
function description lists the possible types of errors. You can find
out which of these occurred by calling *Note `mysql_errno()':
mysql-errno. A string representation of the error may be obtained by
calling *Note `mysql_error()': mysql-error.

MySQL Enterprise

MySQL Enterprise subscribers will find more information about the C API
functions in the Knowledge Base articles, The C API
(https://kb.mysql.com/search.php?cat=search&pagerRow=0&category=17).
Access to the MySQL Knowledge Base collection of articles is one of the
advantages of subscribing to MySQL Enterprise. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: mysql-affected-rows,  Next: mysql-autocommit,  Prev: c-api-functions,  Up: c-api-functions

29.2.3.1 *Note `mysql_affected_rows()': mysql-affected-rows.
............................................................

`my_ulonglong mysql_affected_rows(MYSQL *mysql)'

*Description*

After executing a statement with *Note `mysql_query()': mysql-query. or
*Note `mysql_real_query()': mysql-real-query, returns the number of
rows changed (for `UPDATE'), deleted (for `DELETE'), or inserted (for
`INSERT'). For `SELECT' statements, *Note `mysql_affected_rows()':
mysql-affected-rows. works like *Note `mysql_num_rows()':
mysql-num-rows.

*Return Values*

An integer greater than zero indicates the number of rows affected or
retrieved. Zero indicates that no records were updated for an `UPDATE'
statement, no rows matched the `WHERE' clause in the query or that no
query has yet been executed. -1 indicates that the query returned an
error or that, for a `SELECT' query, *Note `mysql_affected_rows()':
mysql-affected-rows.  was called prior to calling *Note
`mysql_store_result()': mysql-store-result. Because *Note
`mysql_affected_rows()': mysql-affected-rows. returns an unsigned
value, you can check for -1 by comparing the return value to
`(my_ulonglong)-1' (or to `(my_ulonglong)~0', which is equivalent).

*Errors*

None.

*Example*

     char *stmt = "UPDATE products SET cost=cost*1.25 WHERE group=10";
     mysql_query(&mysql,stmt);
     printf("%ld products updated",
            (long) mysql_affected_rows(&mysql));

For `UPDATE' statements, if you specify the `CLIENT_FOUND_ROWS' flag
when connecting to `mysqld', *Note `mysql_affected_rows()':
mysql-affected-rows. returns the number of rows matched by the `WHERE'
clause. Otherwise, the default behavior is to return the number of rows
actually changed.

Note that when you use a `REPLACE' command, *Note
`mysql_affected_rows()': mysql-affected-rows. returns 2 if the new row
replaced an old row, because in this case, one row was inserted after
the duplicate was deleted.

If you use `INSERT ... ON DUPLICATE KEY UPDATE' to insert a row, *Note
`mysql_affected_rows()': mysql-affected-rows. returns 1 if the row is
inserted as a new row and 2 if an existing row is updated.

*Note `mysql_affected_rows()': mysql-affected-rows. returns `0'
following a `CALL' statement for a stored procedure that contains a
statement that modifies rows because in this case *Note
`mysql_insert_id()': mysql-insert-id. applies to `CALL' and not the
statement within the procedure. Within the procedure, you can use
`ROW_COUNT()' at the SQL level to obtain the `AUTO_INCREMENT' value.


File: manual.info,  Node: mysql-autocommit,  Next: mysql-change-user,  Prev: mysql-affected-rows,  Up: c-api-functions

29.2.3.2 *Note `mysql_autocommit()': mysql-autocommit.
......................................................

`my_bool mysql_autocommit(MYSQL *mysql, my_bool mode)'

*Description*

Sets autocommit mode on if `mode' is 1, off if `mode' is 0.

*Return Values*

Zero if successful. Non-zero if an error occurred.

*Errors*

None.


File: manual.info,  Node: mysql-change-user,  Next: mysql-character-set-name,  Prev: mysql-autocommit,  Up: c-api-functions

29.2.3.3 *Note `mysql_change_user()': mysql-change-user.
........................................................

`my_bool mysql_change_user(MYSQL *mysql, const char *user, const char
*password, const char *db)'

*Description*

Changes the user and causes the database specified by `db' to become
the default (current) database on the connection specified by `mysql'.
In subsequent queries, this database is the default for table
references that do not include an explicit database specifier.

*Note `mysql_change_user()': mysql-change-user. fails if the connected
user cannot be authenticated or doesn't have permission to use the
database. In this case, the user and database are not changed.

The `db' parameter may be set to `NULL' if you don't want to have a
default database.

This command resets the state as if one had done a new connect.  (See
*Note auto-reconnect::.) It always performs a `ROLLBACK' of any active
transactions, closes and drops all temporary tables, and unlocks all
locked tables.  Session system variables are reset to the values of the
corresponding global system variables. Prepared statements are released
and `HANDLER' variables are closed.  Locks acquired with `GET_LOCK()'
are released. These effects occur even if the user didn't change.

*Return Values*

Zero for success. Non-zero if an error occurred.

*Errors*

The same that you can get from *Note `mysql_real_connect()':
mysql-real-connect.

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

   * `ER_UNKNOWN_COM_ERROR'

     The MySQL server doesn't implement this command (probably an old
     server).

   * `ER_ACCESS_DENIED_ERROR'

     The user or password was wrong.

   * `ER_BAD_DB_ERROR'

     The database didn't exist.

   * `ER_DBACCESS_DENIED_ERROR'

     The user did not have access rights to the database.

   * `ER_WRONG_DB_NAME'

     The database name was too long.

*Example*

     if (mysql_change_user(&mysql, "user", "password", "new_database"))
     {
        fprintf(stderr, "Failed to change user.  Error: %s\n",
                mysql_error(&mysql));
     }


File: manual.info,  Node: mysql-character-set-name,  Next: mysql-close,  Prev: mysql-change-user,  Up: c-api-functions

29.2.3.4 *Note `mysql_character_set_name()': mysql-character-set-name.
......................................................................

`const char *mysql_character_set_name(MYSQL *mysql)'

*Description*

Returns the default character set name for the current connection.

*Return Values*

The default character set name

*Errors*

None.


File: manual.info,  Node: mysql-close,  Next: mysql-commit,  Prev: mysql-character-set-name,  Up: c-api-functions

29.2.3.5 *Note `mysql_close()': mysql-close.
............................................

`void mysql_close(MYSQL *mysql)'

*Description*

Closes a previously opened connection.  *Note `mysql_close()':
mysql-close. also deallocates the connection handle pointed to by
`mysql' if the handle was allocated automatically by *Note
`mysql_init()': mysql-init. or *Note `mysql_connect()': mysql-connect.

*Return Values*

None.

*Errors*

None.


File: manual.info,  Node: mysql-commit,  Next: mysql-connect,  Prev: mysql-close,  Up: c-api-functions

29.2.3.6 *Note `mysql_commit()': mysql-commit.
..............................................

`my_bool mysql_commit(MYSQL *mysql)'

*Description*

Commits the current transaction.

The action of this function is subject to the value of the
`completion_type' system variable. In particular, if the value of
`completion_type' is 2, the server performs a release after terminating
a transaction and closes the client connection. The client program
should call *Note `mysql_close()': mysql-close. to close the connection
from the client side.

*Return Values*

Zero if successful. Non-zero if an error occurred.

*Errors*

None.


File: manual.info,  Node: mysql-connect,  Next: mysql-create-db,  Prev: mysql-commit,  Up: c-api-functions

29.2.3.7 *Note `mysql_connect()': mysql-connect.
................................................

`MYSQL *mysql_connect(MYSQL *mysql, const char *host, const char *user,
const char *passwd)'

*Description*

This function is deprecated. Use *Note `mysql_real_connect()':
mysql-real-connect. instead.

*Note `mysql_connect()': mysql-connect. attempts to establish a
connection to a MySQL database engine running on `host'.  *Note
`mysql_connect()': mysql-connect. must complete successfully before you
can execute any of the other API functions, with the exception of *Note
`mysql_get_client_info()': mysql-get-client-info.

The meanings of the parameters are the same as for the corresponding
parameters for *Note `mysql_real_connect()': mysql-real-connect. with
the difference that the connection parameter may be `NULL'. In this
case, the C API allocates memory for the connection structure
automatically and frees it when you call *Note `mysql_close()':
mysql-close.  The disadvantage of this approach is that you can't
retrieve an error message if the connection fails. (To get error
information from *Note `mysql_errno()': mysql-errno. or *Note
`mysql_error()': mysql-error, you must provide a valid `MYSQL' pointer.)

*Return Values*

Same as for *Note `mysql_real_connect()': mysql-real-connect.

*Errors*

Same as for *Note `mysql_real_connect()': mysql-real-connect.


File: manual.info,  Node: mysql-create-db,  Next: mysql-data-seek,  Prev: mysql-connect,  Up: c-api-functions

29.2.3.8 *Note `mysql_create_db()': mysql-create-db.
....................................................

`int mysql_create_db(MYSQL *mysql, const char *db)'

*Description*

Creates the database named by the `db' parameter.

This function is deprecated. It is preferable to use *Note
`mysql_query()': mysql-query. to issue an SQL `CREATE DATABASE'
statement instead.

*Return Values*

Zero if the database was created successfully. Non-zero if an error
occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

*Example*

     if(mysql_create_db(&mysql, "my_database"))
     {
        fprintf(stderr, "Failed to create new database.  Error: %s\n",
                mysql_error(&mysql));
     }


File: manual.info,  Node: mysql-data-seek,  Next: mysql-debug,  Prev: mysql-create-db,  Up: c-api-functions

29.2.3.9 *Note `mysql_data_seek()': mysql-data-seek.
....................................................

`void mysql_data_seek(MYSQL_RES *result, my_ulonglong offset)'

*Description*

Seeks to an arbitrary row in a query result set. The `offset' value is
a row number and should be in the range from `0' to *Note
`mysql_num_rows(result)-1': mysql-num-rows.

This function requires that the result set structure contains the
entire result of the query, so *Note `mysql_data_seek()':
mysql-data-seek. may be used only in conjunction with *Note
`mysql_store_result()': mysql-store-result, not with *Note
`mysql_use_result()': mysql-use-result.

*Return Values*

None.

*Errors*

None.


File: manual.info,  Node: mysql-debug,  Next: mysql-drop-db,  Prev: mysql-data-seek,  Up: c-api-functions

29.2.3.10 *Note `mysql_debug()': mysql-debug.
.............................................

`void mysql_debug(const char *debug)'

*Description*

Does a `DBUG_PUSH' with the given string.  *Note `mysql_debug()':
mysql-debug. uses the Fred Fish debug library. To use this function,
you must compile the client library to support debugging. See MySQL
Internals: Porting
(http://forge.mysql.com/wiki/MySQL_Internals_Porting).

*Return Values*

None.

*Errors*

None.

*Example*

The call shown here causes the client library to generate a trace file
in `/tmp/client.trace' on the client machine:

     mysql_debug("d:t:O,/tmp/client.trace");


File: manual.info,  Node: mysql-drop-db,  Next: mysql-dump-debug-info,  Prev: mysql-debug,  Up: c-api-functions

29.2.3.11 *Note `mysql_drop_db()': mysql-drop-db.
.................................................

`int mysql_drop_db(MYSQL *mysql, const char *db)'

*Description*

Drops the database named by the `db' parameter.

This function is deprecated. It is preferable to use *Note
`mysql_query()': mysql-query. to issue an SQL `DROP DATABASE' statement
instead.

*Return Values*

Zero if the database was dropped successfully. Non-zero if an error
occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

*Example*

     if(mysql_drop_db(&mysql, "my_database"))
       fprintf(stderr, "Failed to drop the database: Error: %s\n",
               mysql_error(&mysql));


File: manual.info,  Node: mysql-dump-debug-info,  Next: mysql-eof,  Prev: mysql-drop-db,  Up: c-api-functions

29.2.3.12 *Note `mysql_dump_debug_info()': mysql-dump-debug-info.
.................................................................

`int mysql_dump_debug_info(MYSQL *mysql)'

*Description*

Instructs the server to write some debug information to the log.  For
this to work, the connected user must have the `SUPER' privilege.

*Return Values*

Zero if the command was successful. Non-zero if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-eof,  Next: mysql-errno,  Prev: mysql-dump-debug-info,  Up: c-api-functions

29.2.3.13 *Note `mysql_eof()': mysql-eof.
.........................................

`my_bool mysql_eof(MYSQL_RES *result)'

*Description*

This function is deprecated.  *Note `mysql_errno()': mysql-errno. or
*Note `mysql_error()': mysql-error. may be used instead.

*Note `mysql_eof()': mysql-eof. determines whether the last row of a
result set has been read.

If you acquire a result set from a successful call to *Note
`mysql_store_result()': mysql-store-result, the client receives the
entire set in one operation. In this case, a `NULL' return from *Note
`mysql_fetch_row()': mysql-fetch-row. always means the end of the
result set has been reached and it is unnecessary to call *Note
`mysql_eof()': mysql-eof. When used with *Note `mysql_store_result()':
mysql-store-result, *Note `mysql_eof()': mysql-eof. always returns true.

On the other hand, if you use *Note `mysql_use_result()':
mysql-use-result. to initiate a result set retrieval, the rows of the
set are obtained from the server one by one as you call *Note
`mysql_fetch_row()': mysql-fetch-row. repeatedly.  Because an error may
occur on the connection during this process, a `NULL' return value from
*Note `mysql_fetch_row()': mysql-fetch-row. does not necessarily mean
the end of the result set was reached normally.  In this case, you can
use *Note `mysql_eof()': mysql-eof. to determine what happened. *Note
`mysql_eof()': mysql-eof. returns a non-zero value if the end of the
result set was reached and zero if an error occurred.

Historically, *Note `mysql_eof()': mysql-eof.  predates the standard
MySQL error functions *Note `mysql_errno()': mysql-errno. and *Note
`mysql_error()': mysql-error. Because those error functions provide the
same information, their use is preferred over *Note `mysql_eof()':
mysql-eof, which is deprecated. (In fact, they provide more information,
because *Note `mysql_eof()': mysql-eof. returns only a boolean value
whereas the error functions indicate a reason for the error when one
occurs.)

*Return Values*

Zero if no error occurred. Non-zero if the end of the result set has
been reached.

*Errors*

None.

*Example*

The following example shows how you might use *Note `mysql_eof()':
mysql-eof.:

     mysql_query(&mysql,"SELECT * FROM some_table");
     result = mysql_use_result(&mysql);
     while((row = mysql_fetch_row(result)))
     {
         // do something with data
     }
     if(!mysql_eof(result))  // mysql_fetch_row() failed due to an error
     {
         fprintf(stderr, "Error: %s\n", mysql_error(&mysql));
     }

However, you can achieve the same effect with the standard MySQL error
functions:

     mysql_query(&mysql,"SELECT * FROM some_table");
     result = mysql_use_result(&mysql);
     while((row = mysql_fetch_row(result)))
     {
         // do something with data
     }
     if(mysql_errno(&mysql))  // mysql_fetch_row() failed due to an error
     {
         fprintf(stderr, "Error: %s\n", mysql_error(&mysql));
     }


File: manual.info,  Node: mysql-errno,  Next: mysql-error,  Prev: mysql-eof,  Up: c-api-functions

29.2.3.14 *Note `mysql_errno()': mysql-errno.
.............................................

`unsigned int mysql_errno(MYSQL *mysql)'

*Description*

For the connection specified by `mysql', *Note `mysql_errno()':
mysql-errno. returns the error code for the most recently invoked API
function that can succeed or fail. A return value of zero means that no
error occurred.  Client error message numbers are listed in the MySQL
`errmsg.h' header file. Server error message numbers are listed in
`mysqld_error.h'.  Errors also are listed at *Note error-handling::.

Note that some functions like *Note `mysql_fetch_row()':
mysql-fetch-row. don't set *Note `mysql_errno()': mysql-errno. if they
succeed.

A rule of thumb is that all functions that have to ask the server for
information reset *Note `mysql_errno()': mysql-errno. if they succeed.

MySQL-specific error numbers returned by *Note `mysql_errno()':
mysql-errno. differ from SQLSTATE values returned by *Note
`mysql_sqlstate()': mysql-sqlstate. For example, the `mysql' client
program displays errors using the following format, where `1146' is the
*Note `mysql_errno()': mysql-errno. value and `'42S02'' is the
corresponding *Note `mysql_sqlstate()': mysql-sqlstate. value:

     shell> SELECT * FROM no_such_table;
     ERROR 1146 (42S02): Table 'test.no_such_table' doesn't exist

*Return Values*

An error code value for the last `mysql_XXX()' call, if it failed. zero
means no error occurred.

*Errors*

None.


File: manual.info,  Node: mysql-error,  Next: mysql-escape-string,  Prev: mysql-errno,  Up: c-api-functions

29.2.3.15 *Note `mysql_error()': mysql-error.
.............................................

`const char *mysql_error(MYSQL *mysql)'

*Description*

For the connection specified by `mysql', *Note `mysql_error()':
mysql-error. returns a null-terminated string containing the error
message for the most recently invoked API function that failed. If a
function didn't fail, the return value of *Note `mysql_error()':
mysql-error. may be the previous error or an empty string to indicate
no error.

A rule of thumb is that all functions that have to ask the server for
information reset *Note `mysql_error()': mysql-error. if they succeed.

For functions that reset *Note `mysql_error()': mysql-error, the
following two tests are equivalent:

     if(*mysql_error(&mysql))
     {
       // an error occurred
     }

     if(mysql_error(&mysql)[0])
     {
       // an error occurred
     }

The language of the client error messages may be changed by recompiling
the MySQL client library. Currently, you can choose error messages in
several different languages. See *Note error-message-language::.

*Return Values*

A null-terminated character string that describes the error. An empty
string if no error occurred.

*Errors*

None.


File: manual.info,  Node: mysql-escape-string,  Next: mysql-fetch-field,  Prev: mysql-error,  Up: c-api-functions

29.2.3.16 *Note `mysql_escape_string()': mysql-escape-string.
.............................................................

You should use *Note `mysql_real_escape_string()':
mysql-real-escape-string.  instead!

This function is identical to *Note `mysql_real_escape_string()':
mysql-real-escape-string.  except that *Note
`mysql_real_escape_string()': mysql-real-escape-string.  takes a
connection handler as its first argument and escapes the string
according to the current character set.  *Note `mysql_escape_string()':
mysql-escape-string. does not take a connection argument and does not
respect the current character set.


File: manual.info,  Node: mysql-fetch-field,  Next: mysql-fetch-field-direct,  Prev: mysql-escape-string,  Up: c-api-functions

29.2.3.17 *Note `mysql_fetch_field()': mysql-fetch-field.
.........................................................

`MYSQL_FIELD *mysql_fetch_field(MYSQL_RES *result)'

*Description*

Returns the definition of one column of a result set as a `MYSQL_FIELD'
structure. Call this function repeatedly to retrieve information about
all columns in the result set. *Note `mysql_fetch_field()':
mysql-fetch-field.  returns `NULL' when no more fields are left.

*Note `mysql_fetch_field()': mysql-fetch-field. is reset to return
information about the first field each time you execute a new `SELECT'
query. The field returned by *Note `mysql_fetch_field()':
mysql-fetch-field. is also affected by calls to *Note
`mysql_field_seek()': mysql-field-seek.

If you've called *Note `mysql_query()': mysql-query.  to perform a
`SELECT' on a table but have not called *Note `mysql_store_result()':
mysql-store-result, MySQL returns the default blob length (8KB) if you
call *Note `mysql_fetch_field()': mysql-fetch-field. to ask for the
length of a `BLOB' field. (The 8KB size is chosen because MySQL doesn't
know the maximum length for the `BLOB'. This should be made configurable
sometime.) Once you've retrieved the result set, `field->max_length'
contains the length of the largest value for this column in the
specific query.

*Return Values*

The `MYSQL_FIELD' structure for the current column. `NULL' if no
columns are left.

*Errors*

None.

*Example*

     MYSQL_FIELD *field;

     while((field = mysql_fetch_field(result)))
     {
         printf("field name %s\n", field->name);
     }


File: manual.info,  Node: mysql-fetch-field-direct,  Next: mysql-fetch-fields,  Prev: mysql-fetch-field,  Up: c-api-functions

29.2.3.18 *Note `mysql_fetch_field_direct()': mysql-fetch-field-direct.
.......................................................................

`MYSQL_FIELD *mysql_fetch_field_direct(MYSQL_RES *result, unsigned int
fieldnr)'

*Description*

Given a field number `fieldnr' for a column within a result set,
returns that column's field definition as a `MYSQL_FIELD' structure.
You may use this function to retrieve the definition for an arbitrary
column. The value of `fieldnr' should be in the range from 0 to *Note
`mysql_num_fields(result)-1': mysql-num-fields.

*Return Values*

The `MYSQL_FIELD' structure for the specified column.

*Errors*

None.

*Example*

     unsigned int num_fields;
     unsigned int i;
     MYSQL_FIELD *field;

     num_fields = mysql_num_fields(result);
     for(i = 0; i < num_fields; i++)
     {
         field = mysql_fetch_field_direct(result, i);
         printf("Field %u is %s\n", i, field->name);
     }


File: manual.info,  Node: mysql-fetch-fields,  Next: mysql-fetch-lengths,  Prev: mysql-fetch-field-direct,  Up: c-api-functions

29.2.3.19 *Note `mysql_fetch_fields()': mysql-fetch-fields.
...........................................................

`MYSQL_FIELD *mysql_fetch_fields(MYSQL_RES *result)'

*Description*

Returns an array of all `MYSQL_FIELD' structures for a result set. Each
structure provides the field definition for one column of the result
set.

*Return Values*

An array of `MYSQL_FIELD' structures for all columns of a result set.

*Errors*

None.

*Example*

     unsigned int num_fields;
     unsigned int i;
     MYSQL_FIELD *fields;

     num_fields = mysql_num_fields(result);
     fields = mysql_fetch_fields(result);
     for(i = 0; i < num_fields; i++)
     {
        printf("Field %u is %s\n", i, fields[i].name);
     }


File: manual.info,  Node: mysql-fetch-lengths,  Next: mysql-fetch-row,  Prev: mysql-fetch-fields,  Up: c-api-functions

29.2.3.20 *Note `mysql_fetch_lengths()': mysql-fetch-lengths.
.............................................................

`unsigned long *mysql_fetch_lengths(MYSQL_RES *result)'

*Description*

Returns the lengths of the columns of the current row within a result
set. If you plan to copy field values, this length information is also
useful for optimization, because you can avoid calling `strlen()'. In
addition, if the result set contains binary data, you *must* use this
function to determine the size of the data, because `strlen()' returns
incorrect results for any field containing null characters.

The length for empty columns and for columns containing `NULL' values
is zero. To see how to distinguish these two cases, see the description
for *Note `mysql_fetch_row()': mysql-fetch-row.

*Return Values*

An array of unsigned long integers representing the size of each column
(not including any terminating null characters).  `NULL' if an error
occurred.

*Errors*

*Note `mysql_fetch_lengths()': mysql-fetch-lengths. is valid only for
the current row of the result set. It returns `NULL' if you call it
before calling *Note `mysql_fetch_row()': mysql-fetch-row. or after
retrieving all rows in the result.

*Example*

     MYSQL_ROW row;
     unsigned long *lengths;
     unsigned int num_fields;
     unsigned int i;

     row = mysql_fetch_row(result);
     if (row)
     {
         num_fields = mysql_num_fields(result);
         lengths = mysql_fetch_lengths(result);
         for(i = 0; i < num_fields; i++)
         {
              printf("Column %u is %lu bytes in length.\n",
                     i, lengths[i]);
         }
     }


File: manual.info,  Node: mysql-fetch-row,  Next: mysql-field-count,  Prev: mysql-fetch-lengths,  Up: c-api-functions

29.2.3.21 *Note `mysql_fetch_row()': mysql-fetch-row.
.....................................................

`MYSQL_ROW mysql_fetch_row(MYSQL_RES *result)'

*Description*

Retrieves the next row of a result set. When used after *Note
`mysql_store_result()': mysql-store-result, *Note `mysql_fetch_row()':
mysql-fetch-row. returns `NULL' when there are no more rows to retrieve.
When used after *Note `mysql_use_result()': mysql-use-result, *Note
`mysql_fetch_row()': mysql-fetch-row. returns `NULL' when there are no
more rows to retrieve or if an error occurred.

The number of values in the row is given by *Note
`mysql_num_fields(result)': mysql-num-fields. If `row' holds the return
value from a call to *Note `mysql_fetch_row()': mysql-fetch-row,
pointers to the values are accessed as `row[0]' to
`row[mysql_num_fields(result)-1]'.  `NULL' values in the row are
indicated by `NULL' pointers.

The lengths of the field values in the row may be obtained by calling
*Note `mysql_fetch_lengths()': mysql-fetch-lengths.  Empty fields and
fields containing `NULL' both have length 0; you can distinguish these
by checking the pointer for the field value. If the pointer is `NULL',
the field is `NULL'; otherwise, the field is empty.

*Return Values*

A `MYSQL_ROW' structure for the next row.  `NULL' if there are no more
rows to retrieve or if an error occurred.

*Errors*

Note that error is not reset between calls to *Note
`mysql_fetch_row()': mysql-fetch-row.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

*Example*

     MYSQL_ROW row;
     unsigned int num_fields;
     unsigned int i;

     num_fields = mysql_num_fields(result);
     while ((row = mysql_fetch_row(result)))
     {
        unsigned long *lengths;
        lengths = mysql_fetch_lengths(result);
        for(i = 0; i < num_fields; i++)
        {
            printf("[%.*s] ", (int) lengths[i],
                   row[i] ? row[i] : "NULL");
        }
        printf("\n");
     }


File: manual.info,  Node: mysql-field-count,  Next: mysql-field-seek,  Prev: mysql-fetch-row,  Up: c-api-functions

29.2.3.22 *Note `mysql_field_count()': mysql-field-count.
.........................................................

`unsigned int mysql_field_count(MYSQL *mysql)'

*Description*

Returns the number of columns for the most recent query on the
connection.

The normal use of this function is when *Note `mysql_store_result()':
mysql-store-result. returned `NULL' (and thus you have no result set
pointer). In this case, you can call *Note `mysql_field_count()':
mysql-field-count. to determine whether *Note `mysql_store_result()':
mysql-store-result. should have produced a non-empty result. This
allows the client program to take proper action without knowing whether
the query was a `SELECT' (or `SELECT'-like) statement. The example
shown here illustrates how this may be done.

See *Note null-mysql-store-result::.

*Return Values*

An unsigned integer representing the number of columns in a result set.

*Errors*

None.

*Example*

     MYSQL_RES *result;
     unsigned int num_fields;
     unsigned int num_rows;

     if (mysql_query(&mysql,query_string))
     {
         // error
     }
     else // query succeeded, process any data returned by it
     {
         result = mysql_store_result(&mysql);
         if (result)  // there are rows
         {
             num_fields = mysql_num_fields(result);
             // retrieve rows, then call mysql_free_result(result)
         }
         else  // mysql_store_result() returned nothing; should it have?
         {
             if(mysql_field_count(&mysql) == 0)
             {
                 // query does not return data
                 // (it was not a SELECT)
                 num_rows = mysql_affected_rows(&mysql);
             }
             else // mysql_store_result() should have returned data
             {
                 fprintf(stderr, "Error: %s\n", mysql_error(&mysql));
             }
         }
     }

An alternative is to replace the *Note `mysql_field_count(&mysql)':
mysql-field-count.  call with *Note `mysql_errno(&mysql)': mysql-errno.
In this case, you are checking directly for an error from *Note
`mysql_store_result()': mysql-store-result. rather than inferring from
the value of *Note `mysql_field_count()': mysql-field-count. whether the
statement was a `SELECT'.


File: manual.info,  Node: mysql-field-seek,  Next: mysql-field-tell,  Prev: mysql-field-count,  Up: c-api-functions

29.2.3.23 *Note `mysql_field_seek()': mysql-field-seek.
.......................................................

`MYSQL_FIELD_OFFSET mysql_field_seek(MYSQL_RES *result,
MYSQL_FIELD_OFFSET offset)'

*Description*

Sets the field cursor to the given offset. The next call to *Note
`mysql_fetch_field()': mysql-fetch-field. retrieves the field
definition of the column associated with that offset.

To seek to the beginning of a row, pass an `offset' value of zero.

*Return Values*

The previous value of the field cursor.

*Errors*

None.


File: manual.info,  Node: mysql-field-tell,  Next: mysql-free-result,  Prev: mysql-field-seek,  Up: c-api-functions

29.2.3.24 *Note `mysql_field_tell()': mysql-field-tell.
.......................................................

`MYSQL_FIELD_OFFSET mysql_field_tell(MYSQL_RES *result)'

*Description*

Returns the position of the field cursor used for the last *Note
`mysql_fetch_field()': mysql-fetch-field. This value can be used as an
argument to *Note `mysql_field_seek()': mysql-field-seek.

*Return Values*

The current offset of the field cursor.

*Errors*

None.


File: manual.info,  Node: mysql-free-result,  Next: mysql-get-character-set-info,  Prev: mysql-field-tell,  Up: c-api-functions

29.2.3.25 *Note `mysql_free_result()': mysql-free-result.
.........................................................

`void mysql_free_result(MYSQL_RES *result)'

*Description*

Frees the memory allocated for a result set by *Note
`mysql_store_result()': mysql-store-result, *Note `mysql_use_result()':
mysql-use-result, *Note `mysql_list_dbs()': mysql-list-dbs, and so
forth.  When you are done with a result set, you must free the memory it
uses by calling *Note `mysql_free_result()': mysql-free-result.

Do not attempt to access a result set after freeing it.

*Return Values*

None.

*Errors*

None.


File: manual.info,  Node: mysql-get-character-set-info,  Next: mysql-get-client-info,  Prev: mysql-free-result,  Up: c-api-functions

29.2.3.26 *Note `mysql_get_character_set_info()': mysql-get-character-set-info.
...............................................................................

`void mysql_get_character_set_info(MYSQL *mysql, MY_CHARSET_INFO *cs)'

*Description*

This function provides information about the default client character
set. The default character set may be changed with the *Note
`mysql_set_character_set()': mysql-set-character-set.  function.

*Example*

This example shows the fields that are available in the
`MY_CHARSET_INFO' structure:

     if (!mysql_set_character_set(&mysql, "utf8"))
     {
         MY_CHARSET_INFO cs;
         mysql_get_character_set_info(&mysql, &cs);
         printf("character set information:\n");
         printf("character set+collation number: %d\n", cs.number);
         printf("character set name: %s\n", cs.name);
         printf("collation name: %s\n", cs.csname);
         printf("comment: %s\n", cs.comment);
         printf("directory: %s\n", cs.dir);
         printf("multi byte character min. length: %d\n", cs.mbminlen);
         printf("multi byte character max. length: %d\n", cs.mbmaxlen);
     }


File: manual.info,  Node: mysql-get-client-info,  Next: mysql-get-client-version,  Prev: mysql-get-character-set-info,  Up: c-api-functions

29.2.3.27 *Note `mysql_get_client_info()': mysql-get-client-info.
.................................................................

`const char *mysql_get_client_info(void)'

*Description*

Returns a string that represents the client library version.

*Return Values*

A character string that represents the MySQL client library version.

*Errors*

None.


File: manual.info,  Node: mysql-get-client-version,  Next: mysql-get-host-info,  Prev: mysql-get-client-info,  Up: c-api-functions

29.2.3.28 *Note `mysql_get_client_version()': mysql-get-client-version.
.......................................................................

`unsigned long mysql_get_client_version(void)'

*Description*

Returns an integer that represents the client library version.  The
value has the format `XYYZZ' where `X' is the major version, `YY' is
the release level, and `ZZ' is the version number within the release
level. For example, a value of `40102' represents a client library
version of `4.1.2'.

*Return Values*

An integer that represents the MySQL client library version.

*Errors*

None.


File: manual.info,  Node: mysql-get-host-info,  Next: mysql-get-proto-info,  Prev: mysql-get-client-version,  Up: c-api-functions

29.2.3.29 *Note `mysql_get_host_info()': mysql-get-host-info.
.............................................................

`const char *mysql_get_host_info(MYSQL *mysql)'

*Description*

Returns a string describing the type of connection in use, including
the server hostname.

*Return Values*

A character string representing the server hostname and the connection
type.

*Errors*

None.


File: manual.info,  Node: mysql-get-proto-info,  Next: mysql-get-server-info,  Prev: mysql-get-host-info,  Up: c-api-functions

29.2.3.30 *Note `mysql_get_proto_info()': mysql-get-proto-info.
...............................................................

`unsigned int mysql_get_proto_info(MYSQL *mysql)'

*Description*

Returns the protocol version used by current connection.

*Return Values*

An unsigned integer representing the protocol version used by the
current connection.

*Errors*

None.


File: manual.info,  Node: mysql-get-server-info,  Next: mysql-get-server-version,  Prev: mysql-get-proto-info,  Up: c-api-functions

29.2.3.31 *Note `mysql_get_server_info()': mysql-get-server-info.
.................................................................

`const char *mysql_get_server_info(MYSQL *mysql)'

*Description*

Returns a string that represents the server version number.

*Return Values*

A character string that represents the server version number.

*Errors*

None.


File: manual.info,  Node: mysql-get-server-version,  Next: mysql-get-ssl-cipher,  Prev: mysql-get-server-info,  Up: c-api-functions

29.2.3.32 *Note `mysql_get_server_version()': mysql-get-server-version.
.......................................................................

`unsigned long mysql_get_server_version(MYSQL *mysql)'

*Description*

Returns the version number of the server as an integer.

*Return Values*

A number that represents the MySQL server version in this format:

     major_version*10000 + minor_version *100 + sub_version

For example, 5.1.5 is returned as 50105.

This function is useful in client programs for quickly determining
whether some version-specific server capability exists.

*Errors*

None.


File: manual.info,  Node: mysql-get-ssl-cipher,  Next: mysql-hex-string,  Prev: mysql-get-server-version,  Up: c-api-functions

29.2.3.33 *Note `mysql_get_ssl_cipher()': mysql-get-ssl-cipher.
...............................................................

`const char *mysql_get_ssl_cipher(MYSQL *mysql)'

*Description*

*Note `mysql_get_ssl_cipher()': mysql-get-ssl-cipher. returns the SSL
cipher used for the given connection to the server.  `mysql' is the
connection handler returned from *Note `mysql_init()': mysql-init.

This function was added in MySQL 5.1.11.

*Return Values*

A string naming the SSL cipher used for the connection, or `NULL' if no
cipher is being used.


File: manual.info,  Node: mysql-hex-string,  Next: mysql-info,  Prev: mysql-get-ssl-cipher,  Up: c-api-functions

29.2.3.34 *Note `mysql_hex_string()': mysql-hex-string.
.......................................................

`unsigned long mysql_hex_string(char *to, const char *from, unsigned
long length)'

*Description*

This function is used to create a legal SQL string that you can use in
an SQL statement. See *Note string-syntax::.

The string in `from' is encoded to hexadecimal format, with each
character encoded as two hexadecimal digits.  The result is placed in
`to' and a terminating null byte is appended.

The string pointed to by `from' must be `length' bytes long. You must
allocate the `to' buffer to be at least `length*2+1' bytes long. When
*Note `mysql_hex_string()': mysql-hex-string. returns, the contents of
`to' is a null-terminated string.  The return value is the length of
the encoded string, not including the terminating null character.

The return value can be placed into an SQL statement using either
`0xVALUE' or `X'VALUE'' format.  However, the return value does not
include the `0x' or `X'...''. The caller must supply whichever of those
is desired.

*Example*

     char query[1000],*end;

     end = strmov(query,"INSERT INTO test_table values(");
     end = strmov(end,"0x");
     end += mysql_hex_string(end,"What's this",11);
     end = strmov(end,",0x");
     end += mysql_hex_string(end,"binary data: \0\r\n",16);
     *end++ = ')';

     if (mysql_real_query(&mysql,query,(unsigned int) (end - query)))
     {
        fprintf(stderr, "Failed to insert row, Error: %s\n",
                mysql_error(&mysql));
     }

The `strmov()' function used in the example is included in the
`mysqlclient' library and works like `strcpy()' but returns a pointer
to the terminating null of the first parameter.

*Return Values*

The length of the value placed into `to', not including the terminating
null character.

*Errors*

None.


File: manual.info,  Node: mysql-info,  Next: mysql-init,  Prev: mysql-hex-string,  Up: c-api-functions

29.2.3.35 *Note `mysql_info()': mysql-info.
...........................................

`const char *mysql_info(MYSQL *mysql)'

*Description*

Retrieves a string providing information about the most recently
executed statement, but only for the statements listed here. For other
statements, *Note `mysql_info()': mysql-info.  returns `NULL'. The
format of the string varies depending on the type of statement, as
described here. The numbers are illustrative only; the string contains
values appropriate for the statement.

   * `INSERT INTO ... SELECT ...'

     String format: `Records: 100 Duplicates: 0 Warnings: 0'

   * `INSERT INTO ... VALUES (...),(...),(...)...'

     String format: `Records: 3 Duplicates: 0 Warnings: 0'

   * `LOAD DATA INFILE ...'

     String format: `Records: 1 Deleted: 0 Skipped: 0 Warnings: 0'

   * `ALTER TABLE'

     String format: `Records: 3 Duplicates: 0 Warnings: 0'

   * `UPDATE'

     String format: `Rows matched: 40 Changed: 40 Warnings: 0'

Note that *Note `mysql_info()': mysql-info. returns a non-`NULL' value
for `INSERT ...  VALUES' only for the multiple-row form of the statement
(that is, only if multiple value lists are specified).

*Return Values*

A character string representing additional information about the most
recently executed statement. `NULL' if no information is available for
the statement.

*Errors*

None.


File: manual.info,  Node: mysql-init,  Next: mysql-insert-id,  Prev: mysql-info,  Up: c-api-functions

29.2.3.36 *Note `mysql_init()': mysql-init.
...........................................

`MYSQL *mysql_init(MYSQL *mysql)'

*Description*

Allocates or initializes a `MYSQL' object suitable for *Note
`mysql_real_connect()': mysql-real-connect. If `mysql' is a `NULL'
pointer, the function allocates, initializes, and returns a new object.
Otherwise, the object is initialized and the address of the object is
returned. If *Note `mysql_init()': mysql-init. allocates a new object,
it is freed when *Note `mysql_close()': mysql-close. is called to close
the connection.

*Return Values*

An initialized `MYSQL*' handle.  `NULL' if there was insufficient
memory to allocate a new object.

*Errors*

In case of insufficient memory, `NULL' is returned.


File: manual.info,  Node: mysql-insert-id,  Next: mysql-kill,  Prev: mysql-init,  Up: c-api-functions

29.2.3.37 *Note `mysql_insert_id()': mysql-insert-id.
.....................................................

`my_ulonglong mysql_insert_id(MYSQL *mysql)'

*Description*

Returns the value generated for an `AUTO_INCREMENT' column by the
previous `INSERT' or `UPDATE' statement. Use this function after you
have performed an `INSERT' statement into a table that contains an
`AUTO_INCREMENT' field, or have used `INSERT' or `UPDATE' to set a
column value with `LAST_INSERT_ID(EXPR)'.

The return value of *Note `mysql_insert_id()': mysql-insert-id. is
always zero unless explicitly updated under one of the following
conditions:

   * `INSERT' statements that store a value into an `AUTO_INCREMENT'
     column. This is true whether the value is automatically generated
     by storing the special values `NULL' or `0' into the column, or is
     an explicit non-special value.

   * In the case of a multiple-row `INSERT' statement, the return value
     of *Note `mysql_insert_id()': mysql-insert-id. depends on the
     MySQL server version.

     In MySQL 5.1.12 and later, *Note `mysql_insert_id()':
     mysql-insert-id. returns the _first_ automatically generated
     `AUTO_INCREMENT' value that was _successfully_ inserted. In MySQL
     5.1.11 and earlier, *Note `mysql_insert_id()': mysql-insert-id.
     returns the _first_ automatically generated `AUTO_INCREMENT'
     value, regardless of whether insertion of that value was
     successful.

     If no rows are successfully inserted, *Note `mysql_insert_id()':
     mysql-insert-id. returns 0.

   * Starting in MySQL 5.1.12, if an `INSERT ...  SELECT' statement is
     executed, and no automatically generated value is successfully
     inserted, *Note `mysql_insert_id()': mysql-insert-id. returns the
     ID of the last inserted row.

   * Starting in MySQL 5.1.12, if an `INSERT ...  SELECT' statement uses
     `LAST_INSERT_ID(EXPR)', *Note `mysql_insert_id()':
     mysql-insert-id. returns EXPR.

   * `INSERT' statements that generate an `AUTO_INCREMENT' value by
     inserting `LAST_INSERT_ID(EXPR)' into any column or by updating
     any column to `LAST_INSERT_ID(EXPR)'.

   * If the previous statement returned an error, the value of *Note
     `mysql_insert_id()': mysql-insert-id. is undefined.

For 5.1.12 and later, the return value of *Note `mysql_insert_id()':
mysql-insert-id. can be simplified to the following sequence:

  1. If there is an `AUTO_INCREMENT' column, and an automatically
     generated value was successfully inserted, return the first such
     value.

  2. If `LAST_INSERT_ID(EXPR)' occurred in the statement, return EXPR,
     even if there was an `AUTO_INCREMENT' column in the affected table.

  3. The return value varies depending on the statement used.  When
     called after an `INSERT' statement:

        * If there is an `AUTO_INCREMENT' column in the table, and
          there were some explicit values for this column that were
          successfully inserted into the table, return the last of the
          explicit values.

     When called after an `INSERT ... ON DUPLICATE KEY' statement:

        * If there is an `AUTO_INCREMENT' column in the table and there
          were some explicit succesfully inserted values, or some
          updated rows, return the last of the inserted or updated
          values.

*Note `mysql_insert_id()': mysql-insert-id. returns `0' if the previous
statement does not use an `AUTO_INCREMENT' value. If you need to save
the value for later, be sure to call *Note `mysql_insert_id()':
mysql-insert-id. immediately after the statement that generates the
value.

The value of *Note `mysql_insert_id()': mysql-insert-id.  is affected
only by statements issued within the current client connection. It is
not affected by statements issued by other clients.

The `LAST_INSERT_ID()' SQL function returns the value of the first
automatically generated value that was successfully inserted (starting
from 5.1.12) or the first automatically generated value if any rows were
successfully inserted (before 5.1.12).  `LAST_INSERT_ID()' is not reset
between statements because the value of that function is maintained in
the server. Another difference from *Note `mysql_insert_id()':
mysql-insert-id. is that `LAST_INSERT_ID()' is not updated if you set
an `AUTO_INCREMENT' column to a specific non-special value. See *Note
information-functions::.

*Note `mysql_insert_id()': mysql-insert-id. returns `0' following a
`CALL' statement for a stored procedure that generates an
`AUTO_INCREMENT' value because in this case *Note `mysql_insert_id()':
mysql-insert-id. applies to `CALL' and not the statement within the
procedure. Within the procedure, you can use `LAST_INSERT_ID()' at the
SQL level to obtain the `AUTO_INCREMENT' value.

The reason for the differences between `LAST_INSERT_ID()' and *Note
`mysql_insert_id()': mysql-insert-id. is that `LAST_INSERT_ID()' is
made easy to use in scripts while *Note `mysql_insert_id()':
mysql-insert-id. tries to provide more exact information about what
happens to the `AUTO_INCREMENT' column.

*Return Values*

Described in the preceding discussion.

*Errors*

None.


File: manual.info,  Node: mysql-kill,  Next: mysql-library-end,  Prev: mysql-insert-id,  Up: c-api-functions

29.2.3.38 *Note `mysql_kill()': mysql-kill.
...........................................

`int mysql_kill(MYSQL *mysql, unsigned long pid)'

*Description*

Asks the server to kill the thread specified by `pid'.

This function is deprecated. It is preferable to use *Note
`mysql_query()': mysql-query. to issue an SQL `KILL' statement instead.

*Return Values*

Zero for success. Non-zero if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-library-end,  Next: mysql-library-init,  Prev: mysql-kill,  Up: c-api-functions

29.2.3.39 *Note `mysql_library_end()': mysql-library-end.
.........................................................

`void mysql_library_end(void)'

*Description*

This function finalizes the MySQL library. You should call it when you
are done using the library (for example, after disconnecting from the
server). The action taken by the call depends on whether your
application is linked to the MySQL client library or the MySQL embedded
server library. For a client program linked against the
`libmysqlclient' library by using the `-lmysqlclient' flag, *Note
`mysql_library_end()': mysql-library-end. performs some memory
management to clean up. For an embedded server application linked
against the `libmysqld' library by using the `-lmysqld' flag, *Note
`mysql_library_end()': mysql-library-end. shuts down the embedded
server and then cleans up.

See *Note c-api-function-overview::, and *Note mysql-library-init::,
for usage information.


File: manual.info,  Node: mysql-library-init,  Next: mysql-list-dbs,  Prev: mysql-library-end,  Up: c-api-functions

29.2.3.40 *Note `mysql_library_init()': mysql-library-init.
...........................................................

`int mysql_library_init(int argc, char **argv, char **groups)'

*Description*

This function should be called to initialize the MySQL library before
you call any other MySQL function. If your application uses the
embedded server, this call starts the server and initializes any
subsystems (`mysys', `InnoDB', and so forth) that the server uses.

In a non-multi-threaded environment, the call to *Note
`mysql_library_init()': mysql-library-init. may be omitted, because
*Note `mysql_init()': mysql-init.  will invoke it automatically as
necessary. However, *Note `mysql_library_init()': mysql-library-init.
is not thread-safe in a multi-threaded environment, and thus neither is
*Note `mysql_init()': mysql-init, which calls *Note
`mysql_library_init()': mysql-library-init. You must either call *Note
`mysql_library_init()': mysql-library-init. prior to spawning any
threads, or else use a mutex to protect the call, whether you invoke
*Note `mysql_library_init()': mysql-library-init. or indirectly via
*Note `mysql_init()': mysql-init.  This should be done prior to any
other client library call.

After your application is done using the MySQL library, call *Note
`mysql_library_end()': mysql-library-end. to clean up. See *Note
mysql-library-end::.

The `argc' and `argv' arguments are analogous to the arguments to
`main()'. The first element of `argv' is ignored (it typically contains
the program name). For convenience, `argc' may be `0' (zero) if there
are no command-line arguments for the server.  *Note
`mysql_library_init()': mysql-library-init. makes a copy of the
arguments so it is safe to destroy `argv' or `groups' after the call.

If you want to connect to an external server without starting the
embedded server, you have to specify a negative value for `argc'.

The `groups' argument should be an array of strings that indicate the
groups in option files from which options should be read. See *Note
option-files::. The final entry in the array should be `NULL'. For
convenience, if the `groups' argument itself is `NULL', the `[server]'
and `[embedded]' groups are used by default.

See *Note c-api-function-overview::, for additional usage information.

*Example*

     #include <mysql.h>
     #include <stdlib.h>

     static char *server_args[] = {
       "this_program",       /* this string is not used */
       "--datadir=.",
       "--key_buffer_size=32M"
     };
     static char *server_groups[] = {
       "embedded",
       "server",
       "this_program_SERVER",
       (char *)NULL
     };

     int main(void) {
       if (mysql_library_init(sizeof(server_args) / sizeof(char *),
                             server_args, server_groups)) {
         fprintf(stderr, "could not initialize MySQL library\n");
         exit(1);
       }

       /* Use any MySQL API functions here */

       mysql_library_end();

       return EXIT_SUCCESS;
     }

*Return Values*

Zero if successful. Non-zero if an error occurred.


File: manual.info,  Node: mysql-list-dbs,  Next: mysql-list-fields,  Prev: mysql-library-init,  Up: c-api-functions

29.2.3.41 *Note `mysql_list_dbs()': mysql-list-dbs.
...................................................

`MYSQL_RES *mysql_list_dbs(MYSQL *mysql, const char *wild)'

*Description*

Returns a result set consisting of database names on the server that
match the simple regular expression specified by the `wild' parameter.
`wild' may contain the wildcard characters ``%'' or ``_'', or may be a
`NULL' pointer to match all databases. Calling *Note
`mysql_list_dbs()': mysql-list-dbs. is similar to executing the query
`SHOW databases [LIKE WILD]'.

You must free the result set with *Note `mysql_free_result()':
mysql-free-result.

*Return Values*

A `MYSQL_RES' result set for success.  `NULL' if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-list-fields,  Next: mysql-list-processes,  Prev: mysql-list-dbs,  Up: c-api-functions

29.2.3.42 *Note `mysql_list_fields()': mysql-list-fields.
.........................................................

`MYSQL_RES *mysql_list_fields(MYSQL *mysql, const char *table, const
char *wild)'

*Description*

Returns a result set consisting of field names in the given table that
match the simple regular expression specified by the `wild' parameter.
`wild' may contain the wildcard characters ``%'' or ``_'', or may be a
`NULL' pointer to match all fields. Calling *Note
`mysql_list_fields()': mysql-list-fields. is similar to executing the
query `SHOW COLUMNS FROM TBL_NAME [LIKE WILD]'.

Note that it's recommended that you use `SHOW COLUMNS FROM TBL_NAME'
instead of *Note `mysql_list_fields()': mysql-list-fields.

You must free the result set with *Note `mysql_free_result()':
mysql-free-result.

*Return Values*

A `MYSQL_RES' result set for success.  `NULL' if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-list-processes,  Next: mysql-list-tables,  Prev: mysql-list-fields,  Up: c-api-functions

29.2.3.43 *Note `mysql_list_processes()': mysql-list-processes.
...............................................................

`MYSQL_RES *mysql_list_processes(MYSQL *mysql)'

*Description*

Returns a result set describing the current server threads. This is the
same kind of information as that reported by `mysqladmin processlist'
or a `SHOW PROCESSLIST' query.

You must free the result set with *Note `mysql_free_result()':
mysql-free-result.

*Return Values*

A `MYSQL_RES' result set for success.  `NULL' if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-list-tables,  Next: mysql-more-results,  Prev: mysql-list-processes,  Up: c-api-functions

29.2.3.44 *Note `mysql_list_tables()': mysql-list-tables.
.........................................................

`MYSQL_RES *mysql_list_tables(MYSQL *mysql, const char *wild)'

*Description*

Returns a result set consisting of table names in the current database
that match the simple regular expression specified by the `wild'
parameter. `wild' may contain the wildcard characters ``%'' or ``_'',
or may be a `NULL' pointer to match all tables. Calling *Note
`mysql_list_tables()': mysql-list-tables. is similar to executing the
query `SHOW tables [LIKE WILD]'.

You must free the result set with *Note `mysql_free_result()':
mysql-free-result.

*Return Values*

A `MYSQL_RES' result set for success.  `NULL' if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-more-results,  Next: mysql-next-result,  Prev: mysql-list-tables,  Up: c-api-functions

29.2.3.45 *Note `mysql_more_results()': mysql-more-results.
...........................................................

`my_bool mysql_more_results(MYSQL *mysql)'

*Description*

This function is used when you execute multiple statements specified as
a single statement string, or when you execute `CALL' statements, which
can return multiple result sets.

*Note `mysql_more_results()': mysql-more-results. true if more results
exist from the currently executed statement, in which case the
application must call *Note `mysql_next_result()': mysql-next-result.
to fetch the results.

*Return Values*

`TRUE' (1) if more results exist.  `FALSE' (0) if no more results exist.

In most cases, you can call *Note `mysql_next_result()':
mysql-next-result. instead to test whether more results exist and
initiate retrieval if so.

See *Note c-api-multiple-queries::, and *Note mysql-next-result::.

*Errors*

None.


File: manual.info,  Node: mysql-next-result,  Next: mysql-num-fields,  Prev: mysql-more-results,  Up: c-api-functions

29.2.3.46 *Note `mysql_next_result()': mysql-next-result.
.........................................................

`int mysql_next_result(MYSQL *mysql)'

*Description*

This function is used when you execute multiple statements specified as
a single statement string, or when you execute `CALL' statements, which
can return multiple result sets.

If more statement results exist, *Note `mysql_next_result()':
mysql-next-result. reads the next statement result and returns the
status back to the application.

Before calling *Note `mysql_next_result()': mysql-next-result, you must
call *Note `mysql_free_result()': mysql-free-result. for the preceding
statement if it is a query that returned a result set.

After calling *Note `mysql_next_result()': mysql-next-result. the state
of the connection is as if you had called *Note `mysql_real_query()':
mysql-real-query. or *Note `mysql_query()': mysql-query. for the next
statement. This means that you can call *Note `mysql_store_result()':
mysql-store-result, *Note `mysql_warning_count()': mysql-warning-count,
*Note `mysql_affected_rows()': mysql-affected-rows, and so forth.

If *Note `mysql_next_result()': mysql-next-result. returns an error, no
other statements are executed and there are no more results to fetch.

If your program executes stored procedures with the `CALL' SQL
statement, you _must_ set the `CLIENT_MULTI_RESULTS' flag explicitly, or
implicitly by setting `CLIENT_MULTI_STATEMENTS' when you call *Note
`mysql_real_connect()': mysql-real-connect. This is because each `CALL'
returns a result to indicate the call status, in addition to any
results sets that might be returned by statements executed within the
procedure.  In addition, because `CALL' can return multiple results,
you should process those results using a loop that calls *Note
`mysql_next_result()': mysql-next-result. to determine whether there
are more results.

For an example that shows how to use *Note `mysql_next_result()':
mysql-next-result, see *Note c-api-multiple-queries::.

*Return Values*

*Return Value*            *Description*
0                         Successful and there are more results
-1                        Successful and there are no more results
>0                        An error occurred

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order. For example if you
     didn't call *Note `mysql_use_result()': mysql-use-result. for a
     previous result set.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-num-fields,  Next: mysql-num-rows,  Prev: mysql-next-result,  Up: c-api-functions

29.2.3.47 *Note `mysql_num_fields()': mysql-num-fields.
.......................................................

`unsigned int mysql_num_fields(MYSQL_RES *result)'

To pass a `MYSQL*' argument instead, use `unsigned int
mysql_field_count(MYSQL *mysql)'.

*Description*

Returns the number of columns in a result set.

Note that you can get the number of columns either from a pointer to a
result set or to a connection handle. You would use the connection
handle if *Note `mysql_store_result()': mysql-store-result. or *Note
`mysql_use_result()': mysql-use-result. returned `NULL' (and thus you
have no result set pointer). In this case, you can call *Note
`mysql_field_count()': mysql-field-count. to determine whether *Note
`mysql_store_result()': mysql-store-result. should have produced a
non-empty result. This allows the client program to take proper action
without knowing whether the query was a `SELECT' (or `SELECT'-like)
statement. The example shown here illustrates how this may be done.

See *Note null-mysql-store-result::.

*Return Values*

An unsigned integer representing the number of columns in a result set.

*Errors*

None.

*Example*

     MYSQL_RES *result;
     unsigned int num_fields;
     unsigned int num_rows;

     if (mysql_query(&mysql,query_string))
     {
         // error
     }
     else // query succeeded, process any data returned by it
     {
         result = mysql_store_result(&mysql);
         if (result)  // there are rows
         {
             num_fields = mysql_num_fields(result);
             // retrieve rows, then call mysql_free_result(result)
         }
         else  // mysql_store_result() returned nothing; should it have?
         {
             if (mysql_errno(&mysql))
             {
                fprintf(stderr, "Error: %s\n", mysql_error(&mysql));
             }
             else if (mysql_field_count(&mysql) == 0)
             {
                 // query does not return data
                 // (it was not a SELECT)
                 num_rows = mysql_affected_rows(&mysql);
             }
         }
     }

An alternative (if you know that your query should have returned a
result set) is to replace the *Note `mysql_errno(&mysql)': mysql-errno.
call with a check whether *Note `mysql_field_count(&mysql)':
mysql-field-count.  returns 0. This happens only if something went
wrong.


File: manual.info,  Node: mysql-num-rows,  Next: mysql-options,  Prev: mysql-num-fields,  Up: c-api-functions

29.2.3.48 *Note `mysql_num_rows()': mysql-num-rows.
...................................................

`my_ulonglong mysql_num_rows(MYSQL_RES *result)'

*Description*

Returns the number of rows in the result set.

The use of *Note `mysql_num_rows()': mysql-num-rows.  depends on
whether you use *Note `mysql_store_result()': mysql-store-result. or
*Note `mysql_use_result()': mysql-use-result. to return the result set.
If you use *Note `mysql_store_result()': mysql-store-result, *Note
`mysql_num_rows()': mysql-num-rows. may be called immediately. If you
use *Note `mysql_use_result()': mysql-use-result, *Note
`mysql_num_rows()': mysql-num-rows. does not return the correct value
until all the rows in the result set have been retrieved.

*Note `mysql_num_rows()': mysql-num-rows. is intended for use with
statements that return a result set, such as `SELECT'. For statements
such as `INSERT', `UPDATE', or `DELETE', the number of affected rows
can be obtained with *Note `mysql_affected_rows()': mysql-affected-rows.

*Return Values*

The number of rows in the result set.

*Errors*

None.


File: manual.info,  Node: mysql-options,  Next: mysql-ping,  Prev: mysql-num-rows,  Up: c-api-functions

29.2.3.49 *Note `mysql_options()': mysql-options.
.................................................

`int mysql_options(MYSQL *mysql, enum mysql_option option, const void
*arg)'

*Description*

Can be used to set extra connect options and affect behavior for a
connection. This function may be called multiple times to set several
options.

*Note `mysql_options()': mysql-options. should be called after *Note
`mysql_init()': mysql-init. and before *Note `mysql_connect()':
mysql-connect. or *Note `mysql_real_connect()': mysql-real-connect.

The `option' argument is the option that you want to set; the `arg'
argument is the value for the option. If the option is an integer,
`arg' should point to the value of the integer.

The following list describes the possible options, their effect, and
how `arg' is used for each option. Several of the options apply only
when the application is linked against the `libmysqld' embedded server
library and are unused for applications linked against the `libmysql'
client library. For option descriptions that indicate `arg' is unused,
its value is irrelevant; it is conventional to pass 0.

   * `MYSQL_INIT_COMMAND' (argument type: `char *')

     Statement to execute when connecting to the MySQL server.
     Automatically re-executed if reconnection occurs.

   * `MYSQL_OPT_COMPRESS' (argument: not used)

     Use the compressed client/server protocol.

   * `MYSQL_OPT_CONNECT_TIMEOUT' (argument type: `unsigned int *')

     Connect timeout in seconds.

   * `MYSQL_OPT_GUESS_CONNECTION' (argument: not used)

     For an application linked against the `libmysqld' embedded server
     library, this allows the library to guess whether to use the
     embedded server or a remote server. `Guess' means that if the
     hostname is set and is not `localhost', it uses a remote server.
     This behavior is the default.  `MYSQL_OPT_USE_EMBEDDED_CONNECTION'
     and `MYSQL_OPT_USE_REMOTE_CONNECTION' can be used to override it.
     This option is ignored for applications linked against the
     `libmysqlclient' client library.

   * `MYSQL_OPT_LOCAL_INFILE' (argument type: optional pointer to
     `unsigned int')

     If no pointer is given or if pointer points to an `unsigned int'
     that has a non-zero value, the `LOAD LOCAL INFILE' statement is
     enabled.

   * `MYSQL_OPT_NAMED_PIPE' (argument: not used)

     Use named pipes to connect to a MySQL server on Windows, if the
     server allows named-pipe connections.

   * `MYSQL_OPT_PROTOCOL' (argument type: `unsigned int *')

     Type of protocol to use. Should be one of the enum values of
     `mysql_protocol_type' defined in `mysql.h'.

   * `MYSQL_OPT_READ_TIMEOUT' (argument type: `unsigned int *')

     The timeout in seconds for attempts to read from the server.  Each
     attempt uses this timeout value and there are retries if
     necessary, so the total effective timeout value is three times the
     option value. You can set the value so that a lost connection can
     be detected earlier than the TCP/IP `Close_Wait_Timeout' value of
     10 minutes.  This option works only for TCP/IP connections, and
     only for Windows prior to MySQL 5.1.12.

   * `MYSQL_OPT_RECONNECT' (argument type: `my_bool *')

     Enable or disable automatic reconnection to the server if the
     connection is found to have been lost. Reconnect is off by
     default; this option provides a way to set reconnection behavior
     explicitly.

     Note: *Note `mysql_real_connect()': mysql-real-connect.
     incorrectly reset the `MYSQL_OPT_RECONNECT' option to its default
     value before MySQL 5.1.6. Therefore, prior to that version, if you
     want reconnect to be enabled for each connection, you must call
     *Note `mysql_options()': mysql-options. with the
     `MYSQL_OPT_RECONNECT' option after each call to *Note
     `mysql_real_connect()': mysql-real-connect. This is not necessary
     as of 5.1.6: Call *Note `mysql_options()': mysql-options. only
     before *Note `mysql_real_connect()': mysql-real-connect. as usual.

   * `MYSQL_OPT_SET_CLIENT_IP' (argument type: `char *')

     For an application linked against the `libmysqld' embedded server
     library (when `libmysqld' is compiled with authentication
     support), this means that the user is considered to have connected
     from the specified IP address (specified as a string) for
     authentication purposes. This option is ignored for applications
     linked against the `libmysqlclient' client library.

   * `MYSQL_OPT_SSL_VERIFY_SERVER_CERT' (argument type: `my_bool *')

     Enable or disable verification of the server's Common Name value
     in its certificate against the hostname used when connecting to
     the server. The connection is rejected if there is a mismatch.
     This feature can be used to prevent man-in-the-middle attacks.
     Verification is disabled by default. Added in MySQL 5.1.11.

   * `MYSQL_OPT_USE_EMBEDDED_CONNECTION' (argument: not used)

     For an application linked against the `libmysqld' embedded server
     library, this forces the use of the embedded server for the
     connection.  This option is ignored for applications linked
     against the `libmysqlclient' client library.

   * `MYSQL_OPT_USE_REMOTE_CONNECTION' (argument: not used)

     For an application linked against the `libmysqld' embedded server
     library, this forces the use of a remote server for the
     connection. This option is ignored for applications linked against
     the `libmysqlclient' client library.

   * `MYSQL_OPT_USE_RESULT' (argument: not used)

     This option is unused.

   * `MYSQL_OPT_WRITE_TIMEOUT' (argument type: `unsigned int *')

     The timeout in seconds for attempts to write to the server.  Each
     attempt uses this timeout value and there are `net_retry_count'
     retries if necessary, so the total effective timeout value is
     `net_retry_count' times the option value.  This option works only
     for TCP/IP connections, and only for Windows prior to MySQL 5.1.12.

   * `MYSQL_READ_DEFAULT_FILE' (argument type: `char *')

     Read options from the named option file instead of from `my.cnf'.

   * `MYSQL_READ_DEFAULT_GROUP' (argument type: `char *')

     Read options from the named group from `my.cnf' or the file
     specified with `MYSQL_READ_DEFAULT_FILE'.

   * `MYSQL_REPORT_DATA_TRUNCATION' (argument type: `my_bool *')

     Enable or disable reporting of data truncation errors for prepared
     statements via the `error' member of `MYSQL_BIND' structures.
     (Default: enabled.)

   * `MYSQL_SECURE_AUTH' (argument type: `my_bool *')

     Whether to connect to a server that does not support the password
     hashing used in MySQL 4.1.1 and later.

   * `MYSQL_SET_CHARSET_DIR' (argument type: `char *')

     The pathname to the directory that contains character set
     definition files.

   * `MYSQL_SET_CHARSET_NAME' (argument type: `char *')

     The name of the character set to use as the default character set.

   * `MYSQL_SHARED_MEMORY_BASE_NAME' (argument type: `char *')

     The name of the shared-memory object for communication to the
     server on Windows, if the server supports shared-memory
     connections. Should have the same value as the
     `--shared-memory-base-name' option used for the `mysqld' server
     you want to connect to.

The `client' group is always read if you use `MYSQL_READ_DEFAULT_FILE'
or `MYSQL_READ_DEFAULT_GROUP'.

The specified group in the option file may contain the following
options:

*Option*                  *Description*
`character-sets-dir=PATH' The directory where character sets are
                          installed.
`compress'                Use the compressed client/server protocol.
`connect-timeout=SECONDS' Connect timeout in seconds. On Linux this
                          timeout is also used for waiting for the first
                          answer from the server.
`database=DB_NAME'        Connect to this database if no database was
                          specified in the connect command.
`debug'                   Debug options.
`default-character-set=CHARSET_NAME'The default character set to use.
`disable-local-infile'    Disable use of `LOAD DATA LOCAL'.
`host=HOST_NAME'          Default hostname.
`init-command=STMT'       Statement to execute when connecting to MySQL
                          server. Automatically re-executed if
                          reconnection occurs.
`interactive-timeout=SECONDS'Same as specifying `CLIENT_INTERACTIVE' to
                          *Note `mysql_real_connect()':
                          mysql-real-connect.  See *Note
                          mysql-real-connect::.
`local-infile[={0|1}]'    If no argument or non-zero argument, enable
                          use of `LOAD DATA LOCAL'; otherwise disable.
`max_allowed_packet=BYTES'Maximum size of packet that client can read
                          from server.
`multi-queries',          Allow multiple result sets from
`multi-results'           multiple-statement executions or stored
                          procedures.
`multi-statements'        Allow the client to send multiple statements
                          in a single string (separated by ``;'').
`password=PASSWORD'       Default password.
`pipe'                    Use named pipes to connect to a MySQL server
                          on Windows.
`port=PORT_NUM'           Default port number.
`protocol={TCP|SOCKET|PIPE|MEMORY}'The protocol to use when connecting to the
                          server.
`return-found-rows'       Tell *Note `mysql_info()': mysql-info. to
                          return found rows instead of updated rows when
                          using `UPDATE'.
`shared-memory-base-name=NAME'Shared-memory name to use to connect to server.
`socket=PATH'             Default socket file.
`ssl-ca=FILE_NAME'        Certificate Authority file.
`ssl-capath=PATH'         Certificate Authority directory.
`ssl-cert=FILE_NAME'      Certificate file.
`ssl-cipher=CIPHER_LIST'  Allowable SSL ciphers.
`ssl-key=FILE_NAME'       Key file.
`timeout=SECONDS'         Like `connect-timeout'.
`user'                    Default user.

`timeout' has been replaced by `connect-timeout', but `timeout' is
still supported in MySQL 5.1 for backward compatibility.

For more information about option files, see *Note option-files::.

Before MySQL 5.1.18, the `arg' argument was declared as `char *'.

*Return Values*

Zero for success. Non-zero if you specify an unknown option.

*Example*

     MYSQL mysql;

     mysql_init(&mysql);
     mysql_options(&mysql,MYSQL_OPT_COMPRESS,0);
     mysql_options(&mysql,MYSQL_READ_DEFAULT_GROUP,"odbc");
     if (!mysql_real_connect(&mysql,"host","user","passwd","database",0,NULL,0))
     {
         fprintf(stderr, "Failed to connect to database: Error: %s\n",
               mysql_error(&mysql));
     }

This code requests that the client use the compressed client/server
protocol and read the additional options from the `odbc' section in the
`my.cnf' file.


File: manual.info,  Node: mysql-ping,  Next: mysql-query,  Prev: mysql-options,  Up: c-api-functions

29.2.3.50 *Note `mysql_ping()': mysql-ping.
...........................................

`int mysql_ping(MYSQL *mysql)'

*Description*

Checks whether the connection to the server is working. If the
connection has gone down, an attempt to reconnect is made unless
auto-reconnect is disabled.

This function can be used by clients that remain idle for a long while,
to check whether the server has closed the connection and reconnect if
necessary.

*Return Values*

Zero if the connection to the server is alive. Non-zero if an error
occurred. A non-zero return does not indicate whether the MySQL server
itself is down; the connection might be broken for other reasons such
as network problems.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-query,  Next: mysql-real-connect,  Prev: mysql-ping,  Up: c-api-functions

29.2.3.51 *Note `mysql_query()': mysql-query.
.............................................

`int mysql_query(MYSQL *mysql, const char *stmt_str)'

*Description*

Executes the SQL statement pointed to by the null-terminated string
`stmt_str'. Normally, the string must consist of a single SQL statement
and you should not add a terminating semicolon (``;'') or `\g' to the
statement. If multiple-statement execution has been enabled, the string
can contain several statements separated by semicolons. See *Note
c-api-multiple-queries::.

*Note `mysql_query()': mysql-query. cannot be used for statements that
contain binary data; you must use *Note `mysql_real_query()':
mysql-real-query. instead.  (Binary data may contain the ``\0''
character, which *Note `mysql_query()': mysql-query. interprets as the
end of the statement string.)

If you want to know whether the statement should return a result set,
you can use *Note `mysql_field_count()': mysql-field-count. to check
for this. See *Note mysql-field-count::.

*Return Values*

Zero if the statement was successful. Non-zero if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-real-connect,  Next: mysql-real-escape-string,  Prev: mysql-query,  Up: c-api-functions

29.2.3.52 *Note `mysql_real_connect()': mysql-real-connect.
...........................................................

`MYSQL *mysql_real_connect(MYSQL *mysql, const char *host, const char
*user, const char *passwd, const char *db, unsigned int port, const
char *unix_socket, unsigned long client_flag)'

*Description*

*Note `mysql_real_connect()': mysql-real-connect. attempts to establish
a connection to a MySQL database engine running on `host'.  *Note
`mysql_real_connect()': mysql-real-connect. must complete successfully
before you can execute any other API functions that require a valid
`MYSQL' connection handle structure.

The parameters are specified as follows:

   * The first parameter should be the address of an existing `MYSQL'
     structure. Before calling *Note `mysql_real_connect()':
     mysql-real-connect. you must call *Note `mysql_init()':
     mysql-init. to initialize the `MYSQL' structure. You can change a
     lot of connect options with the *Note `mysql_options()':
     mysql-options. call. See *Note mysql-options::.

   * The value of `host' may be either a hostname or an IP address. If
     `host' is `NULL' or the string `"localhost"', a connection to the
     local host is assumed: For Windows, the client connects using a
     shared-memory connection, if the server has shared-memory
     connections enabled. Otherwise, TCP/IP is used. For Unix, the
     client connects using a Unix socket file. For local connections,
     you can also influence the type of connection to use with the
     `MYSQL_OPT_PROTOCOL' or `MYSQL_OPT_NAMED_PIPE' options to *Note
     `mysql_options()': mysql-options. The type of connection must be
     supported by the server. For a `host' value of `"."' on Windows,
     the client connects using a named pipe, if the server has
     named-pipe connections enabled. If named-pipe connections are not
     enabled, an error occurs.

   * The `user' parameter contains the user's MySQL login ID. If `user'
     is `NULL' or the empty string `""', the current user is assumed.
     Under Unix, this is the current login name. Under Windows ODBC,
     the current username must be specified explicitly. See the MyODBC
     section of *Note connectors::.

   * The `passwd' parameter contains the password for `user'. If
     `passwd' is `NULL', only entries in the `user' table for the user
     that have a blank (empty) password field are checked for a match.
     This allows the database administrator to set up the MySQL
     privilege system in such a way that users get different privileges
     depending on whether they have specified a password.

     *Note*:

     Do not attempt to encrypt the password before calling *Note
     `mysql_real_connect()': mysql-real-connect.; password encryption
     is handled automatically by the client API.

   * The `user' and `passwd' parameters use whatever character set has
     been configured for the `MYSQL' object. By default, this is
     `latin1', but can be changed by calling *Note
     `mysql_options(mysql, MYSQL_SET_CHARSET_NAME, "CHARSET_NAME")':
     mysql-options. prior to connecting.

   * `db' is the database name. If `db' is not `NULL', the connection
     sets the default database to this value.

   * If `port' is not 0, the value is used as the port number for the
     TCP/IP connection. Note that the `host' parameter determines the
     type of the connection.

   * If `unix_socket' is not `NULL', the string specifies the socket or
     named pipe that should be used. Note that the `host' parameter
     determines the type of the connection.

   * The value of `client_flag' is usually 0, but can be set to a
     combination of the following flags to enable certain features:

     *Flag Name*             *Flag Description*
     `CLIENT_COMPRESS'       Use compression protocol.
     `CLIENT_FOUND_ROWS'     Return the number of found (matched) rows,
                             not the number of changed rows.
     `CLIENT_IGNORE_SIGPIPE' Prevents the client library from installing
                             a `SIGPIPE' signal handler. This can be
                             used to avoid conflicts with a handler that
                             the application has already installed.
     `CLIENT_IGNORE_SPACE'   Allow spaces after function names. Makes
                             all functions names reserved words.
     `CLIENT_INTERACTIVE'    Allow `interactive_timeout' seconds
                             (instead of `wait_timeout' seconds) of
                             inactivity before closing the connection.
                             The client's session `wait_timeout'
                             variable is set to the value of the session
                             `interactive_timeout' variable.
     `CLIENT_LOCAL_FILES'    Enable `LOAD DATA LOCAL' handling.
     `CLIENT_MULTI_RESULTS'  Tell the server that the client can handle
                             multiple result sets from
                             multiple-statement executions or stored
                             procedures.  This is automatically set if
                             `CLIENT_MULTI_STATEMENTS' is set.  See the
                             note following this table for more
                             information about this flag.
     `CLIENT_MULTI_STATEMENTS'Tell the server that the client may send
                             multiple statements in a single string
                             (separated by ``;''). If this flag is not
                             set, multiple-statement execution is
                             disabled. See the note following this table
                             for more information about this flag.
     `CLIENT_NO_SCHEMA'      Don't allow the DB_NAME.TBL_NAME.COL_NAME
                             syntax. This is for ODBC. It causes the
                             parser to generate an error if you use that
                             syntax, which is useful for trapping bugs
                             in some ODBC programs.
     `CLIENT_ODBC'           Unused.
     `CLIENT_SSL'            Use SSL (encrypted protocol). This option
                             should not be set by application programs;
                             it is set internally in the client library.
                             Instead, use *Note `mysql_ssl_set()':
                             mysql-ssl-set.  before calling *Note
                             `mysql_real_connect()': mysql-real-connect.

If your program uses the `CALL' SQL statement to execute stored
procedures that produce result sets, you _must_ set the
`CLIENT_MULTI_RESULTS' flag, either explicitly, or implicitly by setting
`CLIENT_MULTI_STATEMENTS' when you call *Note `mysql_real_connect()':
mysql-real-connect. This is because each such stored procedure produces
multiple results: the result sets returned by statements executed
within the procedure, as well as a result to indicate the call status.

If you enable `CLIENT_MULTI_STATEMENTS' or `CLIENT_MULTI_RESULTS', you
should process the result for every call to *Note `mysql_query()':
mysql-query. or *Note `mysql_real_query()': mysql-real-query. by using a
loop that calls *Note `mysql_next_result()': mysql-next-result. to
determine whether there are more results. For an example, see *Note
c-api-multiple-queries::.

For some parameters, it is possible to have the value taken from an
option file rather than from an explicit value in the *Note
`mysql_real_connect()': mysql-real-connect. call. To do this, call
*Note `mysql_options()': mysql-options.  with the
`MYSQL_READ_DEFAULT_FILE' or `MYSQL_READ_DEFAULT_GROUP' option before
calling *Note `mysql_real_connect()': mysql-real-connect.  Then, in the
*Note `mysql_real_connect()': mysql-real-connect. call, specify the
`no-value' value for each parameter to be read from an option file:

   * For `host', specify a value of `NULL' or the empty string (`""').

   * For `user', specify a value of `NULL' or the empty string.

   * For `passwd', specify a value of `NULL'. (For the password, a
     value of the empty string in the *Note `mysql_real_connect()':
     mysql-real-connect. call cannot be overridden in an option file,
     because the empty string indicates explicitly that the MySQL
     account must have an empty password.)

   * For `db', specify a value of `NULL' or the empty string.

   * For `port', specify a value of 0.

   * For `unix_socket', specify a value of `NULL'.

If no value is found in an option file for a parameter, its default
value is used as indicated in the descriptions given earlier in this
section.

*Return Values*

A `MYSQL*' connection handle if the connection was successful, `NULL'
if the connection was unsuccessful. For a successful connection, the
return value is the same as the value of the first parameter.

*Errors*

   * `CR_CONN_HOST_ERROR'

     Failed to connect to the MySQL server.

   * `CR_CONNECTION_ERROR'

     Failed to connect to the local MySQL server.

   * `CR_IPSOCK_ERROR'

     Failed to create an IP socket.

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_SOCKET_CREATE_ERROR'

     Failed to create a Unix socket.

   * `CR_UNKNOWN_HOST'

     Failed to find the IP address for the hostname.

   * `CR_VERSION_ERROR'

     A protocol mismatch resulted from attempting to connect to a
     server with a client library that uses a different protocol
     version.

   * `CR_NAMEDPIPEOPEN_ERROR'

     Failed to create a named pipe on Windows.

   * `CR_NAMEDPIPEWAIT_ERROR'

     Failed to wait for a named pipe on Windows.

   * `CR_NAMEDPIPESETSTATE_ERROR'

     Failed to get a pipe handler on Windows.

   * `CR_SERVER_LOST'

     If `connect_timeout' > 0 and it took longer than `connect_timeout'
     seconds to connect to the server or if the server died while
     executing the `init-command'.

*Example*

     MYSQL mysql;

     mysql_init(&mysql);
     mysql_options(&mysql,MYSQL_READ_DEFAULT_GROUP,"your_prog_name");
     if (!mysql_real_connect(&mysql,"host","user","passwd","database",0,NULL,0))
     {
         fprintf(stderr, "Failed to connect to database: Error: %s\n",
               mysql_error(&mysql));
     }

By using *Note `mysql_options()': mysql-options. the MySQL library
reads the `[client]' and `[your_prog_name]' sections in the `my.cnf'
file which ensures that your program works, even if someone has set up
MySQL in some non-standard way.

Note that upon connection, *Note `mysql_real_connect()':
mysql-real-connect. sets the `reconnect' flag (part of the `MYSQL'
structure) to a value of `1' in versions of the API older than 5.0.3, or
`0' in newer versions. A value of `1' for this flag indicates that if a
statement cannot be performed because of a lost connection, to try
reconnecting to the server before giving up. You can use the
`MYSQL_OPT_RECONNECT' option to *Note `mysql_options()': mysql-options.
to control reconnection behavior.


File: manual.info,  Node: mysql-real-escape-string,  Next: mysql-real-query,  Prev: mysql-real-connect,  Up: c-api-functions

29.2.3.53 *Note `mysql_real_escape_string()': mysql-real-escape-string.
.......................................................................

`unsigned long mysql_real_escape_string(MYSQL *mysql, char *to, const
char *from, unsigned long length)'

Note that `mysql' must be a valid, open connection. This is needed
because the escaping depends on the character set in use by the server.

*Description*

This function is used to create a legal SQL string that you can use in
an SQL statement. See *Note string-syntax::.

The string in `from' is encoded to an escaped SQL string, taking into
account the current character set of the connection. The result is
placed in `to' and a terminating null byte is appended. Characters
encoded are `NUL' (ASCII 0), ``\n'', ``\r'', ``\'', ``''', ``"'', and
Control-Z (see *Note literals::). (Strictly speaking, MySQL requires
only that backslash and the quote character used to quote the string in
the query be escaped. This function quotes the other characters to make
them easier to read in log files.)

The string pointed to by `from' must be `length' bytes long. You must
allocate the `to' buffer to be at least `length*2+1' bytes long. (In
the worst case, each character may need to be encoded as using two
bytes, and you need room for the terminating null byte.) When *Note
`mysql_real_escape_string()': mysql-real-escape-string.  returns, the
contents of `to' is a null-terminated string. The return value is the
length of the encoded string, not including the terminating null
character.

If you need to change the character set of the connection, you should
use the *Note `mysql_set_character_set()': mysql-set-character-set.
function rather than executing a `SET NAMES' (or `SET CHARACTER SET')
statement.  *Note `mysql_set_character_set()': mysql-set-character-set.
works like `SET NAMES' but also affects the character set used by *Note
`mysql_real_escape_string()': mysql-real-escape-string, which `SET
NAMES' does not.

*Example*

     char query[1000],*end;

     end = strmov(query,"INSERT INTO test_table values(");
     *end++ = '\'';
     end += mysql_real_escape_string(&mysql, end,"What's this",11);
     *end++ = '\'';
     *end++ = ',';
     *end++ = '\'';
     end += mysql_real_escape_string(&mysql, end,"binary data: \0\r\n",16);
     *end++ = '\'';
     *end++ = ')';

     if (mysql_real_query(&mysql,query,(unsigned int) (end - query)))
     {
        fprintf(stderr, "Failed to insert row, Error: %s\n",
                mysql_error(&mysql));
     }

The `strmov()' function used in the example is included in the
`mysqlclient' library and works like `strcpy()' but returns a pointer
to the terminating null of the first parameter.

*Return Values*

The length of the value placed into `to', not including the terminating
null character.

*Errors*

None.


File: manual.info,  Node: mysql-real-query,  Next: mysql-refresh,  Prev: mysql-real-escape-string,  Up: c-api-functions

29.2.3.54 *Note `mysql_real_query()': mysql-real-query.
.......................................................

`int mysql_real_query(MYSQL *mysql, const char *stmt_str, unsigned long
length)'

*Description*

Executes the SQL statement pointed to by `stmt_str', which should be a
string `length' bytes long. Normally, the string must consist of a
single SQL statement and you should not add a terminating semicolon
(``;'') or `\g' to the statement. If multiple-statement execution has
been enabled, the string can contain several statements separated by
semicolons. See *Note c-api-multiple-queries::.

*Note `mysql_query()': mysql-query. cannot be used for statements that
contain binary data; you must use *Note `mysql_real_query()':
mysql-real-query. instead.  (Binary data may contain the ``\0''
character, which *Note `mysql_query()': mysql-query. interprets as the
end of the statement string.) In addition, *Note `mysql_real_query()':
mysql-real-query. is faster than *Note `mysql_query()': mysql-query.
because it does not call `strlen()' on the statement string.

If you want to know whether the statement should return a result set,
you can use *Note `mysql_field_count()': mysql-field-count. to check
for this. See *Note mysql-field-count::.

*Return Values*

Zero if the statement was successful. Non-zero if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-refresh,  Next: mysql-reload,  Prev: mysql-real-query,  Up: c-api-functions

29.2.3.55 *Note `mysql_refresh()': mysql-refresh.
.................................................

`int mysql_refresh(MYSQL *mysql, unsigned int options)'

*Description*

This function flushes tables or caches, or resets replication server
information. The connected user must have the `RELOAD' privilege.

The `options' argument is a bit mask composed from any combination of
the following values. Multiple values can be OR'ed together to perform
multiple operations with a single call.

   * `REFRESH_GRANT'

     Refresh the grant tables, like `FLUSH PRIVILEGES'.

   * `REFRESH_LOG'

     Flush the logs, like `FLUSH LOGS'.

   * `REFRESH_TABLES'

     Flush the table cache, like `FLUSH TABLES'.

   * `REFRESH_HOSTS'

     Flush the host cache, like `FLUSH HOSTS'.

   * `REFRESH_STATUS'

     Reset status variables, like `FLUSH STATUS'.

   * `REFRESH_THREADS'

     Flush the thread cache.

   * `REFRESH_SLAVE'

     On a slave replication server, reset the master server information
     and restart the slave, like `RESET SLAVE'.

   * `REFRESH_MASTER'

     On a master replication server, remove the binary log files listed
     in the binary log index and truncate the index file, like `RESET
     MASTER'.

*Return Values*

Zero for success. Non-zero if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-reload,  Next: mysql-rollback,  Prev: mysql-refresh,  Up: c-api-functions

29.2.3.56 *Note `mysql_reload()': mysql-reload.
...............................................

`int mysql_reload(MYSQL *mysql)'

*Description*

Asks the MySQL server to reload the grant tables. The connected user
must have the `RELOAD' privilege.

This function is deprecated. It is preferable to use *Note
`mysql_query()': mysql-query. to issue an SQL `FLUSH PRIVILEGES'
statement instead.

*Return Values*

Zero for success. Non-zero if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-rollback,  Next: mysql-row-seek,  Prev: mysql-reload,  Up: c-api-functions

29.2.3.57 *Note `mysql_rollback()': mysql-rollback.
...................................................

`my_bool mysql_rollback(MYSQL *mysql)'

*Description*

Rolls back the current transaction.

The action of this function is subject to the value of the
`completion_type' system variable. In particular, if the value of
`completion_type' is 2, the server performs a release after terminating
a transaction and closes the client connection. The client program
should call *Note `mysql_close()': mysql-close. to close the connection
from the client side.

*Return Values*

Zero if successful. Non-zero if an error occurred.

*Errors*

None.


File: manual.info,  Node: mysql-row-seek,  Next: mysql-row-tell,  Prev: mysql-rollback,  Up: c-api-functions

29.2.3.58 *Note `mysql_row_seek()': mysql-row-seek.
...................................................

`MYSQL_ROW_OFFSET mysql_row_seek(MYSQL_RES *result, MYSQL_ROW_OFFSET
offset)'

*Description*

Sets the row cursor to an arbitrary row in a query result set.  The
`offset' value is a row offset that should be a value returned from
*Note `mysql_row_tell()': mysql-row-tell. or from *Note
`mysql_row_seek()': mysql-row-seek. This value is not a row number; if
you want to seek to a row within a result set by number, use *Note
`mysql_data_seek()': mysql-data-seek. instead.

This function requires that the result set structure contains the
entire result of the query, so *Note `mysql_row_seek()':
mysql-row-seek. may be used only in conjunction with *Note
`mysql_store_result()': mysql-store-result, not with *Note
`mysql_use_result()': mysql-use-result.

*Return Values*

The previous value of the row cursor. This value may be passed to a
subsequent call to *Note `mysql_row_seek()': mysql-row-seek.

*Errors*

None.


File: manual.info,  Node: mysql-row-tell,  Next: mysql-select-db,  Prev: mysql-row-seek,  Up: c-api-functions

29.2.3.59 *Note `mysql_row_tell()': mysql-row-tell.
...................................................

`MYSQL_ROW_OFFSET mysql_row_tell(MYSQL_RES *result)'

*Description*

Returns the current position of the row cursor for the last *Note
`mysql_fetch_row()': mysql-fetch-row. This value can be used as an
argument to *Note `mysql_row_seek()': mysql-row-seek.

You should use *Note `mysql_row_tell()': mysql-row-tell.  only after
*Note `mysql_store_result()': mysql-store-result, not after *Note
`mysql_use_result()': mysql-use-result.

*Return Values*

The current offset of the row cursor.

*Errors*

None.


File: manual.info,  Node: mysql-select-db,  Next: mysql-set-character-set,  Prev: mysql-row-tell,  Up: c-api-functions

29.2.3.60 *Note `mysql_select_db()': mysql-select-db.
.....................................................

`int mysql_select_db(MYSQL *mysql, const char *db)'

*Description*

Causes the database specified by `db' to become the default (current)
database on the connection specified by `mysql'. In subsequent queries,
this database is the default for table references that do not include an
explicit database specifier.

*Note `mysql_select_db()': mysql-select-db. fails unless the connected
user can be authenticated as having permission to use the database.

*Return Values*

Zero for success. Non-zero if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-set-character-set,  Next: mysql-set-local-infile-default,  Prev: mysql-select-db,  Up: c-api-functions

29.2.3.61 *Note `mysql_set_character_set()': mysql-set-character-set.
.....................................................................

`int mysql_set_character_set(MYSQL *mysql, const char *csname)'

*Description*

This function is used to set the default character set for the current
connection. The string `csname' specifies a valid character set name.
The connection collation becomes the default collation of the character
set. This function works like the `SET NAMES' statement, but also sets
the value of `mysql->charset', and thus affects the character set used
by *Note `mysql_real_escape_string()': mysql-real-escape-string.

*Return Values*

Zero for success. Non-zero if an error occurred.

*Example*

     MYSQL mysql;

     mysql_init(&mysql);
     if (!mysql_real_connect(&mysql,"host","user","passwd","database",0,NULL,0))
     {
         fprintf(stderr, "Failed to connect to database: Error: %s\n",
               mysql_error(&mysql));
     }

     if (!mysql_set_character_set(&mysql, "utf8"))
     {
         printf("New client character set: %s\n",
                mysql_character_set_name(&mysql));
     }


File: manual.info,  Node: mysql-set-local-infile-default,  Next: mysql-set-local-infile-handler,  Prev: mysql-set-character-set,  Up: c-api-functions

29.2.3.62 *Note `mysql_set_local_infile_default()': mysql-set-local-infile-default.
...................................................................................

`void mysql_set_local_infile_default(MYSQL *mysql);'

*Description*

Sets the `LOAD LOCAL DATA INFILE' handler callback functions to the
defaults used internally by the C client library. The library calls
this function automatically if *Note
`mysql_set_local_infile_handler()': mysql-set-local-infile-handler.
has not been called or does not supply valid functions for each of its
callbacks.

The *Note `mysql_set_local_infile_default()':
mysql-set-local-infile-default.  function was added in MySQL 4.1.2.

*Return Values*

None.

*Errors*

None.


File: manual.info,  Node: mysql-set-local-infile-handler,  Next: mysql-set-server-option,  Prev: mysql-set-local-infile-default,  Up: c-api-functions

29.2.3.63 *Note `mysql_set_local_infile_handler()': mysql-set-local-infile-handler.
...................................................................................

`void mysql_set_local_infile_handler(MYSQL *mysql, int
(*local_infile_init)(void **, const char *, void *), int
(*local_infile_read)(void *, char *, unsigned int), void
(*local_infile_end)(void *), int (*local_infile_error)(void *, char*,
unsigned int), void *userdata);'

*Description*

This function installs callbacks to be used during the execution of
`LOAD DATA LOCAL INFILE' statements. It enables application programs to
exert control over local (client-side) data file reading. The arguments
are the connection handler, a set of pointers to callback functions, and
a pointer to a data area that the callbacks can use to share
information.

To use *Note `mysql_set_local_infile_handler()':
mysql-set-local-infile-handler, you must write the following callback
functions:

     int
     local_infile_init(void **ptr, const char *filename, void *userdata);

The initialization function. This is called once to do any setup
necessary, open the data file, allocate data structures, and so forth.
The first `void**' argument is a pointer to a pointer. You can set the
pointer (that is, `*ptr') to a value that will be passed to each of the
other callbacks (as a `void*'). The callbacks can use this pointed-to
value to maintain state information. The `userdata' argument is the
same value that is passed to *Note `mysql_set_local_infile_handler()':
mysql-set-local-infile-handler.

The initialization function should return zero for success, non-zero
for an error.

     int
     local_infile_read(void *ptr, char *buf, unsigned int buf_len);

The data-reading function. This is called repeatedly to read the data
file. `buf' points to the buffer where the read data should be stored,
and `buf_len' is the maximum number of bytes that the callback can read
and store in the buffer. (It can read fewer bytes, but should not read
more.)

The return value is the number of bytes read, or zero when no more data
could be read (this indicates EOF). Return a value less than zero if an
error occurs.

     void
     local_infile_end(void *ptr)

The termination function. This is called once after
`local_infile_read()' has returned zero (EOF) or an error. This
function should deallocate any memory allocated by
`local_infile_init()' and perform any other cleanup necessary. It is
invoked even if the initalization function returns an error.

     int
     local_infile_error(void *ptr,
                        char *error_msg,
                        unsigned int error_msg_len);

The error-handling function. This is called to get a textual error
message to return to the user in case any of your other functions
returns an error. `error_msg' points to the buffer into which the
message should be written, and `error_msg_len' is the length of the
buffer.  The message should be written as a null-terminated string, so
the message can be at most `error_msg_len'-1 bytes long.

The return value is the error number.

Typically, the other callbacks store the error message in the data
structure pointed to by `ptr', so that `local_infile_error()' can copy
the message from there into `error_msg'.

After calling *Note `mysql_set_local_infile_handler()':
mysql-set-local-infile-handler.  in your C code and passing pointers to
your callback functions, you can then issue a `LOAD DATA LOCAL INFILE'
statement (for example, by using *Note `mysql_query()': mysql-query.).
The client library automatically invokes your callbacks. The filename
specified in `LOAD DATA LOCAL INFILE' will be passed as the second
parameter to the `local_infile_init()' callback.

The *Note `mysql_set_local_infile_handler()':
mysql-set-local-infile-handler.  function was added in MySQL 4.1.2.

*Return Values*

None.

*Errors*

None.


File: manual.info,  Node: mysql-set-server-option,  Next: mysql-shutdown,  Prev: mysql-set-local-infile-handler,  Up: c-api-functions

29.2.3.64 *Note `mysql_set_server_option()': mysql-set-server-option.
.....................................................................

`int mysql_set_server_option(MYSQL *mysql, enum enum_mysql_set_option
option)'

*Description*

Enables or disables an option for the connection.  `option' can have
one of the following values:

`MYSQL_OPTION_MULTI_STATEMENTS_ON'   Enable multiple-statement support
`MYSQL_OPTION_MULTI_STATEMENTS_OFF'  Disable multiple-statement support

If you enable multiple-statement support, you should retrieve results
from calls to *Note `mysql_query()': mysql-query. or *Note
`mysql_real_query()': mysql-real-query. by using a loop that calls
*Note `mysql_next_result()': mysql-next-result. to determine whether
there are more results. For an example, see *Note
c-api-multiple-queries::.

Enabling multiple-statement support with
`MYSQL_OPTION_MULTI_STATEMENTS_ON' does not have quite the same effect
as enabling it by passing the `CLIENT_MULTI_STATEMENTS' flag to *Note
`mysql_real_connect()': mysql-real-connect.: `CLIENT_MULTI_STATEMENTS'
also enables `CLIENT_MULTI_RESULTS'. If you are using the `CALL' SQL
statement in your programs, multiple-result support must be enabled;
this means that `MYSQL_OPTION_MULTI_STATEMENTS_ON' by itself is
insufficient to allow the use of `CALL'.

*Return Values*

Zero for success. Non-zero if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `ER_UNKNOWN_COM_ERROR'

     The server didn't support *Note `mysql_set_server_option()':
     mysql-set-server-option.  (which is the case that the server is
     older than 4.1.1) or the server didn't support the option one
     tried to set.


File: manual.info,  Node: mysql-shutdown,  Next: mysql-sqlstate,  Prev: mysql-set-server-option,  Up: c-api-functions

29.2.3.65 *Note `mysql_shutdown()': mysql-shutdown.
...................................................

`int mysql_shutdown(MYSQL *mysql, enum mysql_enum_shutdown_level
shutdown_level)'

*Description*

Asks the database server to shut down. The connected user must have
`SHUTDOWN' privileges. MySQL 5.1 servers support only one type of
shutdown; `shutdown_level' must be equal to `SHUTDOWN_DEFAULT'.
Additional shutdown levels are planned to make it possible to choose
the desired level.  Dynamically linked executables which have been
compiled with older versions of the `libmysqlclient' headers and call
*Note `mysql_shutdown()': mysql-shutdown. need to be used with the old
`libmysqlclient' dynamic library.

The shutdown process is described in *Note server-shutdown::.

*Return Values*

Zero for success. Non-zero if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-sqlstate,  Next: mysql-ssl-set,  Prev: mysql-shutdown,  Up: c-api-functions

29.2.3.66 *Note `mysql_sqlstate()': mysql-sqlstate.
...................................................

`const char *mysql_sqlstate(MYSQL *mysql)'

*Description*

Returns a null-terminated string containing the SQLSTATE error code for
the most recently executed SQL statement. The error code consists of
five characters. `'00000'' means `no error'. The values are specified
by ANSI SQL and ODBC. For a list of possible values, see *Note
error-handling::.

SQLSTATE values returned by *Note `mysql_sqlstate()': mysql-sqlstate.
differ from MySQL-specific error numbers returned by *Note
`mysql_errno()': mysql-errno. For example, the `mysql' client program
displays errors using the following format, where `1146' is the *Note
`mysql_errno()': mysql-errno. value and `'42S02'' is the corresponding
*Note `mysql_sqlstate()': mysql-sqlstate. value:

     shell> SELECT * FROM no_such_table;
     ERROR 1146 (42S02): Table 'test.no_such_table' doesn't exist

Not all MySQL error numbers are mapped to SQLSTATE error codes.  The
value `'HY000'' (general error) is used for unmapped error numbers.

If you call *Note `mysql_sqlstate()': mysql-sqlstate.  after *Note
`mysql_real_connect()': mysql-real-connect.  fails, *Note
`mysql_sqlstate()': mysql-sqlstate. might not return a useful value.
For example, this happens if a host is blocked by the server and the
connection is closed without any SQLSTATE value being sent to the
client.

*Return Values*

A null-terminated character string containing the SQLSTATE error code.

*See Also*

See *Note mysql-errno::, *Note mysql-error::, and *Note
mysql-stmt-sqlstate::.


File: manual.info,  Node: mysql-ssl-set,  Next: mysql-stat,  Prev: mysql-sqlstate,  Up: c-api-functions

29.2.3.67 *Note `mysql_ssl_set()': mysql-ssl-set.
.................................................

`my_bool mysql_ssl_set(MYSQL *mysql, const char *key, const char *cert,
const char *ca, const char *capath, const char *cipher)'

*Description*

*Note `mysql_ssl_set()': mysql-ssl-set. is used for establishing secure
connections using SSL. It must be called before *Note
`mysql_real_connect()': mysql-real-connect.

*Note `mysql_ssl_set()': mysql-ssl-set. does nothing unless OpenSSL
support is enabled in the client library.

`mysql' is the connection handler returned from *Note `mysql_init()':
mysql-init. The other parameters are specified as follows:

   * `key' is the pathname to the key file.

   * `cert' is the pathname to the certificate file.

   * `ca' is the pathname to the certificate authority file.

   * `capath' is the pathname to a directory that contains trusted SSL
     CA certificates in pem format.

   * `cipher' is a list of allowable ciphers to use for SSL encryption.

Any unused SSL parameters may be given as `NULL'.

*Return Values*

This function always returns `0'. If SSL setup is incorrect, *Note
`mysql_real_connect()': mysql-real-connect. returns an error when you
attempt to connect.


File: manual.info,  Node: mysql-stat,  Next: mysql-store-result,  Prev: mysql-ssl-set,  Up: c-api-functions

29.2.3.68 *Note `mysql_stat()': mysql-stat.
...........................................

`const char *mysql_stat(MYSQL *mysql)'

*Description*

Returns a character string containing information similar to that
provided by the `mysqladmin status' command. This includes uptime in
seconds and the number of running threads, questions, reloads, and open
tables.

*Return Values*

A character string describing the server status.  `NULL' if an error
occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-store-result,  Next: mysql-thread-id,  Prev: mysql-stat,  Up: c-api-functions

29.2.3.69 *Note `mysql_store_result()': mysql-store-result.
...........................................................

`MYSQL_RES *mysql_store_result(MYSQL *mysql)'

*Description*

After invoking *Note `mysql_query()': mysql-query. or *Note
`mysql_real_query()': mysql-real-query, you must call *Note
`mysql_store_result()': mysql-store-result. or *Note
`mysql_use_result()': mysql-use-result. for every statement that
successfully produces a result set (`SELECT', `SHOW', `DESCRIBE',
`EXPLAIN', `CHECK TABLE', and so forth). You must also call *Note
`mysql_free_result()': mysql-free-result. after you are done with the
result set.

You don't have to call *Note `mysql_store_result()':
mysql-store-result. or *Note `mysql_use_result()': mysql-use-result.
for other statements, but it does not do any harm or cause any notable
performance degradation if you call *Note `mysql_store_result()':
mysql-store-result. in all cases. You can detect whether the statement
has a result set by checking whether *Note `mysql_store_result()':
mysql-store-result. returns a non-zero value (more about this later on).

If you enable multiple-statement support, you should retrieve results
from calls to *Note `mysql_query()': mysql-query. or *Note
`mysql_real_query()': mysql-real-query. by using a loop that calls
*Note `mysql_next_result()': mysql-next-result. to determine whether
there are more results. For an example, see *Note
c-api-multiple-queries::.

If you want to know whether a statement should return a result set, you
can use *Note `mysql_field_count()': mysql-field-count. to check for
this. See *Note mysql-field-count::.

*Note `mysql_store_result()': mysql-store-result. reads the entire
result of a query to the client, allocates a `MYSQL_RES' structure, and
places the result into this structure.

*Note `mysql_store_result()': mysql-store-result. returns a null
pointer if the statement didn't return a result set (for example, if it
was an `INSERT' statement).

*Note `mysql_store_result()': mysql-store-result. also returns a null
pointer if reading of the result set failed. You can check whether an
error occurred by checking whether *Note `mysql_error()': mysql-error.
returns a non-empty string, *Note `mysql_errno()': mysql-errno.
returns non-zero, or *Note `mysql_field_count()': mysql-field-count.
returns zero.

An empty result set is returned if there are no rows returned.  (An
empty result set differs from a null pointer as a return value.)

After you have called *Note `mysql_store_result()': mysql-store-result.
and gotten back a result that isn't a null pointer, you can call *Note
`mysql_num_rows()': mysql-num-rows. to find out how many rows are in
the result set.

You can call *Note `mysql_fetch_row()': mysql-fetch-row.  to fetch rows
from the result set, or *Note `mysql_row_seek()': mysql-row-seek. and
*Note `mysql_row_tell()': mysql-row-tell. to obtain or set the current
row position within the result set.

See *Note null-mysql-store-result::.

*Return Values*

A `MYSQL_RES' result structure with the results. `NULL' (0) if an error
occurred.

*Errors*

*Note `mysql_store_result()': mysql-store-result. resets *Note
`mysql_error()': mysql-error. and *Note `mysql_errno()': mysql-errno.
if it succeeds.

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-thread-id,  Next: mysql-use-result,  Prev: mysql-store-result,  Up: c-api-functions

29.2.3.70 *Note `mysql_thread_id()': mysql-thread-id.
.....................................................

`unsigned long mysql_thread_id(MYSQL *mysql)'

*Description*

Returns the thread ID of the current connection. This value can be used
as an argument to *Note `mysql_kill()': mysql-kill. to kill the thread.

If the connection is lost and you reconnect with *Note `mysql_ping()':
mysql-ping, the thread ID changes. This means you should not get the
thread ID and store it for later. You should get it when you need it.

*Return Values*

The thread ID of the current connection.

*Errors*

None.


File: manual.info,  Node: mysql-use-result,  Next: mysql-warning-count,  Prev: mysql-thread-id,  Up: c-api-functions

29.2.3.71 *Note `mysql_use_result()': mysql-use-result.
.......................................................

`MYSQL_RES *mysql_use_result(MYSQL *mysql)'

*Description*

After invoking *Note `mysql_query()': mysql-query. or *Note
`mysql_real_query()': mysql-real-query, you must call *Note
`mysql_store_result()': mysql-store-result. or *Note
`mysql_use_result()': mysql-use-result. for every statement that
successfully produces a result set (`SELECT', `SHOW', `DESCRIBE',
`EXPLAIN', `CHECK TABLE', and so forth). You must also call *Note
`mysql_free_result()': mysql-free-result. after you are done with the
result set.

*Note `mysql_use_result()': mysql-use-result. initiates a result set
retrieval but does not actually read the result set into the client like
*Note `mysql_store_result()': mysql-store-result. does.  Instead, each
row must be retrieved individually by making calls to *Note
`mysql_fetch_row()': mysql-fetch-row. This reads the result of a query
directly from the server without storing it in a temporary table or
local buffer, which is somewhat faster and uses much less memory than
*Note `mysql_store_result()': mysql-store-result. The client allocates
memory only for the current row and a communication buffer that may
grow up to `max_allowed_packet' bytes.

On the other hand, you shouldn't use *Note `mysql_use_result()':
mysql-use-result. if you are doing a lot of processing for each row on
the client side, or if the output is sent to a screen on which the user
may type a `^S' (stop scroll). This ties up the server and prevent
other threads from updating any tables from which the data is being
fetched.

When using *Note `mysql_use_result()': mysql-use-result, you must
execute *Note `mysql_fetch_row()': mysql-fetch-row. until a `NULL'
value is returned, otherwise, the unfetched rows are returned as part
of the result set for your next query. The C API gives the error
`Commands out of sync; you can't run this command now' if you forget to
do this!

You may not use *Note `mysql_data_seek()': mysql-data-seek, *Note
`mysql_row_seek()': mysql-row-seek, *Note `mysql_row_tell()':
mysql-row-tell, *Note `mysql_num_rows()': mysql-num-rows, or *Note
`mysql_affected_rows()': mysql-affected-rows. with a result returned
from *Note `mysql_use_result()': mysql-use-result, nor may you issue
other queries until *Note `mysql_use_result()': mysql-use-result. has
finished. (However, after you have fetched all the rows, *Note
`mysql_num_rows()': mysql-num-rows. accurately returns the number of
rows fetched.)

You must call *Note `mysql_free_result()': mysql-free-result. once you
are done with the result set.

When using the `libmysqld' embedded server, the memory benefits are
essentially lost because memory usage incrementally increases with each
row retrieved until *Note `mysql_free_result()': mysql-free-result. is
called.

*Return Values*

A `MYSQL_RES' result structure.  `NULL' if an error occurred.

*Errors*

*Note `mysql_use_result()': mysql-use-result. resets *Note
`mysql_error()': mysql-error. and *Note `mysql_errno()': mysql-errno.
if it succeeds.

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-warning-count,  Prev: mysql-use-result,  Up: c-api-functions

29.2.3.72 *Note `mysql_warning_count()': mysql-warning-count.
.............................................................

`unsigned int mysql_warning_count(MYSQL *mysql)'

*Description*

Returns the number of warnings generated during execution of the
previous SQL statement.

*Return Values*

The warning count.

*Errors*

None.


File: manual.info,  Node: c-api-prepared-statements,  Next: c-api-prepared-statement-datatypes,  Prev: c-api-functions,  Up: c

29.2.4 C API Prepared Statements
--------------------------------

The MySQL client/server protocol provides for the use of prepared
statements. This capability uses the `MYSQL_STMT' statement handler
data structure returned by the *Note `mysql_stmt_init()':
mysql-stmt-init. initialization function. Prepared execution is an
efficient way to execute a statement more than once. The statement is
first parsed to prepare it for execution. Then it is executed one or
more times at a later time, using the statement handle returned by the
initialization function.

Prepared execution is faster than direct execution for statements
executed more than once, primarily because the query is parsed only
once. In the case of direct execution, the query is parsed every time
it is executed. Prepared execution also can provide a reduction of
network traffic because for each execution of the prepared statement,
it is necessary only to send the data for the parameters.

Prepared statements might not provide a performance increase in some
situations. For best results, test your application both with prepared
and non-prepared statements and choose whichever yields best
performance.

Another advantage of prepared statements is that it uses a binary
protocol that makes data transfer between client and server more
efficient.

The following statements can be used as prepared statements: `CREATE
TABLE', `DELETE', `DO', `INSERT', `REPLACE', `SELECT', `SET', `UPDATE',
and most `SHOW' statements.

As of MySQL 5.1.10, the following additional statements are supported:

     ANALYZE TABLE
     OPTIMIZE TABLE
     REPAIR TABLE

As of MySQL 5.1.12, the following additional statements are supported:

     CACHE INDEX
     CHANGE MASTER
     CHECKSUM {TABLE | TABLES}
     {CREATE | RENAME | DROP} DATABASE
     {CREATE | RENAME | DROP} USER
     FLUSH {TABLE | TABLES | TABLES WITH READ LOCK | HOSTS | PRIVILEGES
       | LOGS | STATUS | MASTER | SLAVE | DES_KEY_FILE | USER_RESOURCES}
     GRANT
     REVOKE
     KILL
     LOAD INDEX INTO CACHE
     RESET {MASTER | SLAVE | QUERY CACHE}
     SHOW BINLOG EVENTS
     SHOW CREATE {PROCEDURE | FUNCTION | EVENT | TABLE | VIEW}
     SHOW {AUTHORS | CONTRIBUTORS | WARNINGS | ERRORS}
     SHOW {MASTER | BINARY} LOGS
     SHOW {MASTER | SLAVE} STATUS
     SLAVE {START | STOP}
     INSTALL PLUGIN
     UNINSTALL PLUGIN

Other statements are not yet supported in MySQL 5.1.

MySQL Enterprise

MySQL Enterprise subscribers will find more information about using
prepared statements in the Knowledge Base article, How can I create
server-side prepared statements?
(https://kb.mysql.com/view.php?id=5931). Access to the MySQL Knowledge
Base collection of articles is one of the advantages of subscribing to
MySQL Enterprise. For more information see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: c-api-prepared-statement-datatypes,  Next: c-api-prepared-statement-function-overview,  Prev: c-api-prepared-statements,  Up: c

29.2.5 C API Prepared Statement Data types
------------------------------------------

Prepared statements use several data structures:

   * To prepare a statement, pass the statement string to *Note
     `mysql_stmt_init()': mysql-stmt-init, which returns a pointer to a
     `MYSQL_STMT' data structure.

   * To provide input parameters for a prepared statement, set up
     `MYSQL_BIND' structures and pass them to *Note
     `mysql_stmt_bind_param()': mysql-stmt-bind-param. To receive
     output column values, set up `MYSQL_BIND' structures and pass them
     to *Note `mysql_stmt_bind_result()': mysql-stmt-bind-result.

   * The `MYSQL_TIME' structure is used to transfer temporal data in
     both directions.

The following discussion describes the prepared statement data types in
detail.

   * `MYSQL_STMT'

     This structure represents a prepared statement. A statement is
     created by calling *Note `mysql_stmt_init()': mysql-stmt-init,
     which returns a statement handle (that is, a pointer to a
     `MYSQL_STMT'). The handle is used for all subsequent operations
     with the statement until you close it with *Note
     `mysql_stmt_close()': mysql-stmt-close, at which point the handle
     becomes invalid.

     The `MYSQL_STMT' structure has no members that are intended for
     application use. Also, you should not try to make a copy of a
     `MYSQL_STMT' structure. There is no guarantee that such a copy
     will be usable.

     Multiple statement handles can be associated with a single
     connection. The limit on the number of handles depends on the
     available system resources.

   * `MYSQL_BIND'

     This structure is used both for statement input (data values sent
     to the server) and output (result values returned from the server):

        * For input, `MYSQL_BIND' is used with *Note
          `mysql_stmt_bind_param()': mysql-stmt-bind-param.  to bind
          parameter data values to buffers for use by *Note
          `mysql_stmt_execute()': mysql-stmt-execute.

        * For output, `MYSQL_BIND' is used with *Note
          `mysql_stmt_bind_result()': mysql-stmt-bind-result.  to bind
          result set buffers for use in fetching rows with *Note
          `mysql_stmt_fetch()': mysql-stmt-fetch.

     To use a `MYSQL_BIND' structure, you should zero its contents to
     initialize it, and then set its members appropriately. For
     example, to declare and initialize an array of three `MYSQL_BIND'
     structures, use this code:

          MYSQL_BIND bind[3];
          memset(bind, 0, sizeof(bind));

     The `MYSQL_BIND' structure contains the following members for use
     by application programs. For several of the members, the manner of
     use depends on whether the structure is used for input or output.

        * `enum enum_field_types buffer_type'

          The type of the buffer. This member indicates the data type
          of the C language variable that you are binding to the
          statement parameter. The allowable `buffer_type' values are
          listed later in this section. For input, `buffer_type'
          indicates the type of the variable containing the value that
          you will send to the server. For output, it indicates the
          type of the variable into which you want a value received
          from the server to be stored.

        * `void *buffer'

          A pointer to the buffer to be used for data transfer. This is
          the address of a variable.

          For input, `buffer' is a pointer to the variable in which a
          statement parameter's data value is stored. When you call
          *Note `mysql_stmt_execute()': mysql-stmt-execute, MySQL takes
          the value that you have stored in the variable and uses it in
          place of the corresponding parameter marker in the statement.

          For output, `buffer' is a pointer to the variable in which to
          return a result set column value.  When you call *Note
          `mysql_stmt_fetch()': mysql-stmt-fetch, MySQL returns a
          column value and stores it in this variable. You can access
          the value when the call returns.

          To minimize the need for MySQL to perform type conversions
          between C language values on the client side and SQL values
          on the server side, use variables that have types similar to
          those of the corresponding SQL values. For numeric data
          types, `buffer' should point to a variable of the proper
          numeric C type. (For `char' or integer variables, you should
          also indicate whether the variable has the `unsigned'
          attribute by setting the `is_unsigned' member, described
          later in this list.) For character (non-binary) and binary
          string data types, `buffer' should point to a character
          buffer. For date and time data types, `buffer' should point
          to a `MYSQL_TIME' structure.

          See the notes about type conversions later in the section.

        * `unsigned long buffer_length'

          The actual size of `*buffer' in bytes.  This indicates the
          maximum amount of data that can be stored in the buffer. For
          character and binary C data, the `buffer_length' value
          specifies the length of `*buffer' when used with *Note
          `mysql_stmt_bind_param()': mysql-stmt-bind-param.  to specify
          input values, or the maximum number of output data bytes that
          can be fetched into the buffer when used with *Note
          `mysql_stmt_bind_result()': mysql-stmt-bind-result.

        * `unsigned long *length'

          A pointer to an `unsigned long' variable that indicates the
          actual number of bytes of data stored in `*buffer'. `length'
          is used for character or binary C data.

          For input parameter data binding, `length' points to an
          `unsigned long' variable that indicates the actual length of
          the parameter value stored in `*buffer'; this is used by
          *Note `mysql_stmt_execute()': mysql-stmt-execute.

          For output value binding, the return value of *Note
          `mysql_stmt_fetch()': mysql-stmt-fetch.  determines the
          interpretation of the length:

             * If *Note `mysql_stmt_fetch()': mysql-stmt-fetch.
               returns 0, `*length' indicates the actual length of the
               parameter value.

             * If *Note `mysql_stmt_fetch()': mysql-stmt-fetch.
               returns `MYSQL_DATA_TRUNCATED', `*length' indicates the
               non-truncated length of the parameter value. In this
               case, the minimum of `*length' and `buffer_length'
               indicates the actual length of the value.

          `length' is ignored for numeric and temporal data types
          because the length of the data value is determined by the
          `buffer_type' value.

          If you need to be able to determine the length of a returned
          value before fetching it with *Note `mysql_stmt_fetch()':
          mysql-stmt-fetch, see *Note mysql-stmt-fetch::, for some
          strategies.

        * `my_bool *is_null'

          This member points to a `my_bool' variable that is true if a
          value is `NULL', false if it is not `NULL'. For input, set
          `*is_null' to true to indicate that you are passing a `NULL'
          value as a statement parameter.

          The reason that `is_null' is not a boolean scalar but is
          instead a _pointer_ to a boolean scalar is to provide
          flexibility in how you specify `NULL' values:

             * If your data values are always `NULL', use
               `MYSQL_TYPE_NULL' as the `buffer_type' value when you
               bind the column. The other members do not matter.

             * If your data values are always `NOT NULL', set the other
               members appropriately for the variable you are binding,
               and set `is_null = (my_bool*) 0'.

             * In all other cases, set the other members
               appriopriately, and set `is_null' to the address of a
               `my_bool' variable.  Set that variable's value to true
               or false appropriately between executions to indicate
               whether data values are `NULL' or `NOT NULL',
               respectively.

          For output, the value pointed to by `is_null' is set to true
          after you fetch a row if the result set column value returned
          from the statement is `NULL'.

        * `my_bool is_unsigned'

          This member is used for C variables with data types that can
          be `unsigned' (`char', `short int', `int', `long long int').
          Set `is_unsigned' to true if the variable pointed to by
          `buffer' is `unsigned' and false otherwise. For example, if
          you bind a `signed char' variable to `buffer', specify a type
          code of `MYSQL_TYPE_TINY' and set `is_unsigned' to false. If
          you bind an `unsigned char' instead, the type code is the
          same but `is_unsigned' should be true. (For `char', it is not
          defined whether it is signed or unsigned, so it is best to be
          explicit about signedness by using `signed char' or `unsigned
          char'.)

          `is_unsigned' applies only to the C language variable on the
          client side. It indicates nothing about the signedness of the
          corresponding SQL value on the server side. For example, if
          you use an `int' variable to supply a value for a `BIGINT
          UNSIGNED' column, `is_unsigned' should be false because `int'
          is a signed type. If you use an `unsigned int' variable to
          supply a value for a `BIGINT' column, `is_unsigned' should be
          true because `unsigned int' is an unsigned type. MySQL
          performs the proper conversion between signed and unsigned
          values in both directions, although a warning occurs if
          truncation results.

        * `my_bool *error'

          For output, set this member to point to a `my_bool' variable
          to have truncation information for the parameter stored there
          after a row fetching operation. (Truncation reporting is
          enabled by default, but can be controlled by calling *Note
          `mysql_options()': mysql-options. with the
          `MYSQL_REPORT_DATA_TRUNCATION' option.)  When truncation
          reporting is enabled, *Note `mysql_stmt_fetch()':
          mysql-stmt-fetch.  returns `MYSQL_DATA_TRUNCATED' and
          `*error' is true in the `MYSQL_BIND' structures for
          parameters in which truncation occurred. Truncation indicates
          loss of sign or significant digits, or that a string was too
          long to fit in a column.

   * `MYSQL_TIME'

     This structure is used to send and receive `DATE', `TIME',
     `DATETIME', and `TIMESTAMP' data directly to and from the server.
     Set the `buffer_type' member of a `MYSQL_BIND' structure to one of
     the temporal types (`MYSQL_TYPE_TIME', `MYSQL_TYPE_DATE',
     `MYSQL_TYPE_DATETIME', `MYSQL_TYPE_TIMESTAMP'), and set the
     `buffer' member to point to a `MYSQL_TIME' structure.

     The `MYSQL_TIME' structure contains the members listed in the
     following table.

     *Member*                    *Description*
     `unsigned int year'         The year
     `unsigned int month'        The month of the year
     `unsigned int day'          The day of the month
     `unsigned int hour'         The hour of the day
     `unsigned int minute'       The minute of the hour
     `unsigned int second'       The second of the minute
     `my_bool neg'               A boolean flag to indicate whether the
                                 time is negative
     `unsigned long second_part' The fractional part of the second in
                                 microseconds; currently unused

     Only those parts of a `MYSQL_TIME' structure that apply to a given
     type of temporal value are used. The `year', `month', and `day'
     elements are used for `DATE', `DATETIME', and `TIMESTAMP' values.
     The `hour', `minute', and `second' elements are used for `TIME',
     `DATETIME', and `TIMESTAMP' values. See *Note
     c-api-date-handling::.

The following table shows the allowable values that may be specified in
the `buffer_type' member of `MYSQL_BIND' structures for input values.
The value should be chosen according to the data type of the C language
variable that you are binding. If the variable is `unsigned', you
should also set the `is_unsigned' member to true. The table shows the C
variable types that you can use, the corresponding type codes, and the
SQL data types for which the supplied value can be used without
conversion.

*Input Variable C      `buffer_type' *Value*     *SQL Type of Destination
Type*                                            Value*
`signed char'          `MYSQL_TYPE_TINY'         `TINYINT'
`short int'            `MYSQL_TYPE_SHORT'        `SMALLINT'
`int'                  `MYSQL_TYPE_LONG'         `INT'
`long long int'        `MYSQL_TYPE_LONGLONG'     `BIGINT'
`float'                `MYSQL_TYPE_FLOAT'        `FLOAT'
`double'               `MYSQL_TYPE_DOUBLE'       `DOUBLE'
`MYSQL_TIME'           `MYSQL_TYPE_TIME'         `TIME'
`MYSQL_TIME'           `MYSQL_TYPE_DATE'         `DATE'
`MYSQL_TIME'           `MYSQL_TYPE_DATETIME'     `DATETIME'
`MYSQL_TIME'           `MYSQL_TYPE_TIMESTAMP'    `TIMESTAMP'
`char[]'               `MYSQL_TYPE_STRING' (for  `TEXT, CHAR, VARCHAR'
                       non-binary data)          
`char[]'               `MYSQL_TYPE_BLOB' (for    `BLOB, BINARY, VARBINARY'
                       binary data)              
                       `MYSQL_TYPE_NULL'         `NULL'

The use of `MYSQL_TYPE_NULL' is described earlier in connection with
the `is_null' member.

The following table shows the allowable values that may be specified in
the `buffer_type' member of `MYSQL_BIND' structures for output values.
The value should be chosen according to the data type of the C language
variable that you are binding. If the variable is `unsigned', you
should also set the `is_unsigned' member to true. The table shows the
SQL types of received values, the corresponding type code that such
values have in result set metadata, and the recommended C language data
types to bind to the `MYSQL_BIND' structure to receive the SQL values
without conversion.

If there is a mismatch between the C variable type on the client side
and the corresponding SQL value on the server side, MySQL performs
implicit type conversions in both directions.

*SQL Type of Received  `buffer_type' *Value*     *Output Variable C Type*
Value*                                           
`TINYINT'              `MYSQL_TYPE_TINY'         `signed char'
`SMALLINT'             `MYSQL_TYPE_SHORT'        `short int'
`MEDIUMINT'            `MYSQL_TYPE_INT24'        `int'
`INT'                  `MYSQL_TYPE_LONG'         `int'
`BIGINT'               `MYSQL_TYPE_LONGLONG'     `long long int'
`FLOAT'                `MYSQL_TYPE_FLOAT'        `float'
`DOUBLE'               `MYSQL_TYPE_DOUBLE'       `double'
`DECIMAL'              `MYSQL_TYPE_NEWDECIMAL'   `char[]'
`YEAR'                 `MYSQL_TYPE_SHORT'        `short int'
`TIME'                 `MYSQL_TYPE_TIME'         `MYSQL_TIME'
`DATE'                 `MYSQL_TYPE_DATE'         `MYSQL_TIME'
`DATETIME'             `MYSQL_TYPE_DATETIME'     `MYSQL_TIME'
`TIMESTAMP'            `MYSQL_TYPE_TIMESTAMP'    `MYSQL_TIME'
`CHAR, BINARY'         `MYSQL_TYPE_STRING'       `char[]'
`VARCHAR, VARBINARY'   `MYSQL_TYPE_VAR_STRING'   `char[]'
`TINYBLOB, TINYTEXT'   `MYSQL_TYPE_TINY_BLOB'    `char[]'
`BLOB, TEXT'           `MYSQL_TYPE_BLOB'         `char[]'
`MEDIUMBLOB,           `MYSQL_TYPE_MEDIUM_BLOB'  `char[]'
MEDIUMTEXT'                                      
`LONGBLOB, LONGTEXT'   `MYSQL_TYPE_LONG_BLOB'    `char[]'
`BIT'                  `MYSQL_TYPE_BIT'          `char[]'

MySQL knows the type code for the SQL value on the server side.  The
`buffer_type' value indicates the MySQL the type code of the C variable
that holds the value on the client side. The two codes together tell
MySQL what conversion must be performed, if any. Here are some examples:

   * If you use `MYSQL_TYPE_LONG' with an `int' variable to pass an
     integer value to the server that is to be stored into a `FLOAT'
     column, MySQL converts the value to floating-point format before
     storing it.

   * If you fetch a SQL `MEDIUMINT' column value, but specify a
     `buffer_type' value of `MYSQL_TYPE_LONGLONG' and use a C variable
     of type `long long int' as the destination buffer, MySQL will
     convert the `MEDIUMINT' value (which requires less than 8 bytes)
     for storage into the `long long int' (an 8-byte variable).

   * If you fetch a numeric column with a value of 255 into a `char[4]'
     character array and specify a `buffer_type' value of
     `MYSQL_TYPE_STRING', the resulting value in the array will be a
     4-byte string containing `'255\0''.

   * `DECIMAL' values are returned as strings, which is why the
     corresponding C type is `char[]'. `DECIMAL' values returned by the
     server correspond to the string representation of the original
     server-side value. For example, `12.345' is returned to the client
     as `'12.345''. If you specify `MYSQL_TYPE_NEWDECIMAL' and bind a
     string buffer to the `MYSQL_BIND' structure, *Note
     `mysql_stmt_fetch()': mysql-stmt-fetch. stores the value in the
     buffer without conversion. If instead you specify a numeric
     variable and type code, *Note `mysql_stmt_fetch()':
     mysql-stmt-fetch. converts the string-format `DECIMAL' value to
     numeric form.

   * For the `MYSQL_TYPE_BIT' type code, `BIT' values are returned into
     a string buffer (thus, the corresponding C type is `char[]' here,
     too). The value represents a bit string that requires
     interpretation on the client side. To return the value as a type
     that is easier to deal with, you can cause the value to be cast to
     integer using either of the following types of expressions:

          SELECT bit_col + 0 FROM t
          SELECT CAST(bit_col AS UNSIGNED) FROM t

     To retrieve the value, bind an integer variable large enough to
     hold the value and specify the appropriate corresponding integer
     type code.

Before binding variables to the `MYSQL_BIND' structures that are to be
used for fetching column values, you can check the type codes for each
column of the result set. This might be desirable if you want to
determine which variable types would be best to use to avoid type
conversions. To get the type codes, call *Note
`mysql_stmt_result_metadata()': mysql-stmt-result-metadata.  after
executing the prepared statement with *Note `mysql_stmt_execute()':
mysql-stmt-execute. The metadata provides access to the type codes for
the result set as described in *Note mysql-stmt-result-metadata::, and
*Note c-api-datatypes::.

If you cause the `max_length' member of the `MYSQL_FIELD' column
metadata structures to be set (by calling *Note
`mysql_stmt_attr_set()': mysql-stmt-attr-set.), be aware that the
`max_length' values for the result set indicate the lengths of the
longest string representation of the result values, not the lengths of
the binary representation. That is, `max_length' does not necessarily
correspond to the size of the buffers needed to fetch the values with
the binary protocol used for prepared statements. The size of the
buffers should be chosen according to the types of the variables into
which you fetch the values.

For input character (non-binary) string data (indicated by
`MYSQL_TYPE_STRING'), the value is assumed to be in the character set
indicated by the `character_set_client' system variable. If the value
is stored into a column with a different character set, the appropriate
conversion to that character set occurs. For input binary string data
(indicated by `MYSQL_TYPE_BLOB'), the value is treated as having the
`binary' character set; that is, it is treated as a byte string and no
conversion occurs.

To determine whether output string values in a result set returned from
the server contain binary or non-binary data, check whether the
`charsetnr' value of the result set metadata is 63 (see *Note
c-api-datatypes::). If so, the character set is `binary', which
indicates binary rather than non-binary data. This enables you to
distinguish `BINARY' from `CHAR', `VARBINARY' from `VARCHAR', and the
`BLOB' types from the `TEXT' types.

As of MySQL 5.1.25, metadata changes to tables or views referred to by
prepared statements are detected and cause automatic repreparation of
the statement when it is next executed. For more information, see *Note
statement-repreparation::.


File: manual.info,  Node: c-api-prepared-statement-function-overview,  Next: c-api-prepared-statement-functions,  Prev: c-api-prepared-statement-datatypes,  Up: c

29.2.6 C API Prepared Statement Function Overview
-------------------------------------------------

The functions available for prepared statement processing are
summarized here and described in greater detail in a later section. See
*Note c-api-prepared-statement-functions::.

*Function*              *Description*
*Note                   Returns the number of rows changed, deleted, or
`mysql_stmt_affected_rows()':inserted by prepared `UPDATE', `DELETE', or
mysql-stmt-affected-rows.`INSERT' statement
*Note                   Get value of an attribute for a prepared
`mysql_stmt_attr_get()':statement
mysql-stmt-attr-get.    
*Note                   Sets an attribute for a prepared statement
`mysql_stmt_attr_set()':
mysql-stmt-attr-set.    
*Note                   Associates application data buffers with the
`mysql_stmt_bind_param()':parameter markers in a prepared SQL statement
mysql-stmt-bind-param.  
*Note                   Associates application data buffers with columns
`mysql_stmt_bind_result()':in the result set
mysql-stmt-bind-result. 
*Note                   Frees memory used by prepared statement
`mysql_stmt_close()':   
mysql-stmt-close.       
*Note                   Seeks to an arbitrary row number in a statement
`mysql_stmt_data_seek()':result set
mysql-stmt-data-seek.   
*Note                   Returns the error number for the last statement
`mysql_stmt_errno()':   execution
mysql-stmt-errno.       
*Note                   Returns the error message for the last statement
`mysql_stmt_error()':   execution
mysql-stmt-error.       
*Note                   Executes the prepared statement
`mysql_stmt_execute()': 
mysql-stmt-execute.     
*Note                   Fetches the next row of data from the result set
`mysql_stmt_fetch()':   and returns data for all bound columns
mysql-stmt-fetch.       
*Note                   Fetch data for one column of the current row of
`mysql_stmt_fetch_column()':the result set
mysql-stmt-fetch-column.
*Note                   Returns the number of result columns for the
`mysql_stmt_field_count()':most recent statement
mysql-stmt-field-count. 
*Note                   Free the resources allocated to the statement
`mysql_stmt_free_result()':handle
mysql-stmt-free-result. 
*Note                   Allocates memory for `MYSQL_STMT' structure and
`mysql_stmt_init()':    initializes it
mysql-stmt-init.        
*Note                   Returns the ID generated for an `AUTO_INCREMENT'
`mysql_stmt_insert_id()':column by prepared statement
mysql-stmt-insert-id.   
*Note                   Returns total row count from the buffered
`mysql_stmt_num_rows()':statement result set
mysql-stmt-num-rows.    
*Note                   Returns the number of parameters in a prepared
`mysql_stmt_param_count()':SQL statement
mysql-stmt-param-count. 
*Note                   (Return parameter metadata in the form of a
`mysql_stmt_param_metadata()':result set.) Currently, this function does
mysql-stmt-param-metadata.nothing
*Note                   Prepares an SQL string for execution
`mysql_stmt_prepare()': 
mysql-stmt-prepare.     
*Note                   Reset the statement buffers in the server
`mysql_stmt_reset()':   
mysql-stmt-reset.       
*Note                   Returns prepared statement metadata in the form
`mysql_stmt_result_metadata()':of a result set
mysql-stmt-result-metadata.
*Note                   Seeks to a row offset in a statement result set,
`mysql_stmt_row_seek()':using value returned from *Note
mysql-stmt-row-seek.    `mysql_stmt_row_tell()': mysql-stmt-row-tell.
*Note                   Returns the statement row cursor position
`mysql_stmt_row_tell()':
mysql-stmt-row-tell.    
*Note                   Sends long data in chunks to server
`mysql_stmt_send_long_data()':
mysql-stmt-send-long-data.
*Note                   Returns the SQLSTATE error code for the last
`mysql_stmt_sqlstate()':statement execution
mysql-stmt-sqlstate.    
*Note                   Retrieves the complete result set to the client
`mysql_stmt_store_result()':
mysql-stmt-store-result.

Call *Note `mysql_stmt_init()': mysql-stmt-init. to create a statement
handle, then *Note `mysql_stmt_prepare()': mysql-stmt-prepare. to
prepare it, *Note `mysql_stmt_bind_param()': mysql-stmt-bind-param. to
supply the parameter data, and *Note `mysql_stmt_execute()':
mysql-stmt-execute. to execute the statement. You can repeat the *Note
`mysql_stmt_execute()': mysql-stmt-execute. by changing parameter
values in the respective buffers supplied through *Note
`mysql_stmt_bind_param()': mysql-stmt-bind-param.

If the statement is a `SELECT' or any other statement that produces a
result set, *Note `mysql_stmt_prepare()': mysql-stmt-prepare. also
returns the result set metadata information in the form of a
`MYSQL_RES' result set through *Note `mysql_stmt_result_metadata()':
mysql-stmt-result-metadata.

You can supply the result buffers using *Note
`mysql_stmt_bind_result()': mysql-stmt-bind-result, so that the *Note
`mysql_stmt_fetch()': mysql-stmt-fetch.  automatically returns data to
these buffers. This is row-by-row fetching.

You can also send the text or binary data in chunks to server using
*Note `mysql_stmt_send_long_data()': mysql-stmt-send-long-data. See
*Note mysql-stmt-send-long-data::.

When statement execution has been completed, the statement handle must
be closed using *Note `mysql_stmt_close()': mysql-stmt-close. so that
all resources associated with it can be freed.

If you obtained a `SELECT' statement's result set metadata by calling
*Note `mysql_stmt_result_metadata()': mysql-stmt-result-metadata, you
should also free the metadata using *Note `mysql_free_result()':
mysql-free-result.

*Execution Steps*

To prepare and execute a statement, an application follows these steps:

  1. Create a prepared statement handle with *Note `mysql_stmt_init()':
     mysql-stmt-init. To prepare the statement on the server, call
     *Note `mysql_stmt_prepare()': mysql-stmt-prepare. and pass it a
     string containing the SQL statement.

  2. If the statement produces a result set, call *Note
     `mysql_stmt_result_metadata()': mysql-stmt-result-metadata.  to
     obtain the result set metadata. This metadata is itself in the
     form of result set, albeit a separate one from the one that
     contains the rows returned by the query. The metadata result set
     indicates how many columns are in the result and contains
     information about each column.

  3. Set the values of any parameters using *Note
     `mysql_stmt_bind_param()': mysql-stmt-bind-param. All parameters
     must be set. Otherwise, statement execution returns an error or
     produces unexpected results.

  4. Call *Note `mysql_stmt_execute()': mysql-stmt-execute. to execute
     the statement.

  5. If the statement produces a result set, bind the data buffers to
     use for retrieving the row values by calling *Note
     `mysql_stmt_bind_result()': mysql-stmt-bind-result.

  6. Fetch the data into the buffers row by row by calling *Note
     `mysql_stmt_fetch()': mysql-stmt-fetch. repeatedly until no more
     rows are found.

  7. Repeat steps 3 through 6 as necessary, by changing the parameter
     values and re-executing the statement.

When *Note `mysql_stmt_prepare()': mysql-stmt-prepare. is called, the
MySQL client/server protocol performs these actions:

   * The server parses the statement and sends the okay status back to
     the client by assigning a statement ID. It also sends total number
     of parameters, a column count, and its metadata if it is a result
     set oriented statement. All syntax and semantics of the statement
     are checked by the server during this call.

   * The client uses this statement ID for the further operations, so
     that the server can identify the statement from among its pool of
     statements.

When *Note `mysql_stmt_execute()': mysql-stmt-execute. is called, the
MySQL client/server protocol performs these actions:

   * The client uses the statement handle and sends the parameter data
     to the server.

   * The server identifies the statement using the ID provided by the
     client, replaces the parameter markers with the newly supplied
     data, and executes the statement. If the statement produces a
     result set, the server sends the data back to the client.
     Otherwise, it sends an okay status and total number of rows
     changed, deleted, or inserted.

When *Note `mysql_stmt_fetch()': mysql-stmt-fetch. is called, the MySQL
client/server protocol performs these actions:

   * The client reads the data from the packet row by row and places it
     into the application data buffers by doing the necessary
     conversions. If the application buffer type is same as that of the
     field type returned from the server, the conversions are
     straightforward.

If an error occurs, you can get the statement error code, error
message, and SQLSTATE value using *Note `mysql_stmt_errno()':
mysql-stmt-errno, *Note `mysql_stmt_error()': mysql-stmt-error, and
*Note `mysql_stmt_sqlstate()': mysql-stmt-sqlstate, respectively.

*Prepared Statement Logging*

For prepared statements that are executed with the *Note
`mysql_stmt_prepare()': mysql-stmt-prepare. and *Note
`mysql_stmt_execute()': mysql-stmt-execute. C API functions, the server
writes `Prepare' and `Execute' lines to the general query log so that
you can tell when statements are prepared and executed.

Suppose that you prepare and execute a statement as follows:

  1. Call *Note `mysql_stmt_prepare()': mysql-stmt-prepare. to prepare
     the statement string `"SELECT ?"'.

  2. Call *Note `mysql_stmt_bind_param()': mysql-stmt-bind-param.  to
     bind the value `3' to the parameter in the prepared statement.

  3. Call *Note `mysql_stmt_execute()': mysql-stmt-execute. to execute
     the prepared statement.

As a result of the preceding calls, the server writes the following
lines to the general query log:

     Prepare  [1] SELECT ?
     Execute  [1] SELECT 3

Each `Prepare' and `Execute' line in the log is tagged with a `[N]'
statement identifier so that you can keep track of which prepared
statement is being logged. N is a positive integer. If there are
multiple prepared statements active simultaneously for the client, N
may be greater than 1. Each `Execute' lines shows a prepared statement
after substitution of data values for `?' parameters.

Version notes: `Prepare' lines are displayed without `[N]' before MySQL
4.1.10. `Execute' lines are not displayed at all before MySQL 4.1.10.


File: manual.info,  Node: c-api-prepared-statement-functions,  Next: c-api-prepared-statement-problems,  Prev: c-api-prepared-statement-function-overview,  Up: c

29.2.7 C API Prepared Statement Function Descriptions
-----------------------------------------------------

* Menu:

* mysql-stmt-affected-rows::     *Note `mysql_stmt_affected_rows()': mysql-stmt-affected-rows.
* mysql-stmt-attr-get::          *Note `mysql_stmt_attr_get()': mysql-stmt-attr-get.
* mysql-stmt-attr-set::          *Note `mysql_stmt_attr_set()': mysql-stmt-attr-set.
* mysql-stmt-bind-param::        *Note `mysql_stmt_bind_param()': mysql-stmt-bind-param.
* mysql-stmt-bind-result::       *Note `mysql_stmt_bind_result()': mysql-stmt-bind-result.
* mysql-stmt-close::             *Note `mysql_stmt_close()': mysql-stmt-close.
* mysql-stmt-data-seek::         *Note `mysql_stmt_data_seek()': mysql-stmt-data-seek.
* mysql-stmt-errno::             *Note `mysql_stmt_errno()': mysql-stmt-errno.
* mysql-stmt-error::             *Note `mysql_stmt_error()': mysql-stmt-error.
* mysql-stmt-execute::           *Note `mysql_stmt_execute()': mysql-stmt-execute.
* mysql-stmt-fetch::             *Note `mysql_stmt_fetch()': mysql-stmt-fetch.
* mysql-stmt-fetch-column::      *Note `mysql_stmt_fetch_column()': mysql-stmt-fetch-column.
* mysql-stmt-field-count::       *Note `mysql_stmt_field_count()': mysql-stmt-field-count.
* mysql-stmt-free-result::       *Note `mysql_stmt_free_result()': mysql-stmt-free-result.
* mysql-stmt-init::              *Note `mysql_stmt_init()': mysql-stmt-init.
* mysql-stmt-insert-id::         *Note `mysql_stmt_insert_id()': mysql-stmt-insert-id.
* mysql-stmt-num-rows::          *Note `mysql_stmt_num_rows()': mysql-stmt-num-rows.
* mysql-stmt-param-count::       *Note `mysql_stmt_param_count()': mysql-stmt-param-count.
* mysql-stmt-param-metadata::    *Note `mysql_stmt_param_metadata()': mysql-stmt-param-metadata.
* mysql-stmt-prepare::           *Note `mysql_stmt_prepare()': mysql-stmt-prepare.
* mysql-stmt-reset::             *Note `mysql_stmt_reset()': mysql-stmt-reset.
* mysql-stmt-result-metadata::   *Note `mysql_stmt_result_metadata()': mysql-stmt-result-metadata.
* mysql-stmt-row-seek::          *Note `mysql_stmt_row_seek()': mysql-stmt-row-seek.
* mysql-stmt-row-tell::          *Note `mysql_stmt_row_tell()': mysql-stmt-row-tell.
* mysql-stmt-send-long-data::    *Note `mysql_stmt_send_long_data()': mysql-stmt-send-long-data.
* mysql-stmt-sqlstate::          *Note `mysql_stmt_sqlstate()': mysql-stmt-sqlstate.
* mysql-stmt-store-result::      *Note `mysql_stmt_store_result()': mysql-stmt-store-result.

To prepare and execute queries, use the functions described in detail
in the following sections.

All functions that operate with a `MYSQL_STMT' structure begin with the
prefix `mysql_stmt_'.

To create a `MYSQL_STMT' handle, use the *Note `mysql_stmt_init()':
mysql-stmt-init. function.


File: manual.info,  Node: mysql-stmt-affected-rows,  Next: mysql-stmt-attr-get,  Prev: c-api-prepared-statement-functions,  Up: c-api-prepared-statement-functions

29.2.7.1 *Note `mysql_stmt_affected_rows()': mysql-stmt-affected-rows.
......................................................................

`my_ulonglong mysql_stmt_affected_rows(MYSQL_STMT *stmt)'

*Description*

Returns the total number of rows changed, deleted, or inserted by the
last executed statement. May be called immediately after *Note
`mysql_stmt_execute()': mysql-stmt-execute. for `UPDATE', `DELETE', or
`INSERT' statements. For `SELECT' statements, *Note
`mysql_stmt_affected_rows()': mysql-stmt-affected-rows.  works like
*Note `mysql_num_rows()': mysql-num-rows.

*Return Values*

An integer greater than zero indicates the number of rows affected or
retrieved. Zero indicates that no records were updated for an `UPDATE'
statement, no rows matched the `WHERE' clause in the query, or that no
query has yet been executed. -1 indicates that the query returned an
error or that, for a `SELECT' query, *Note
`mysql_stmt_affected_rows()': mysql-stmt-affected-rows. was called
prior to calling *Note `mysql_stmt_store_result()':
mysql-stmt-store-result.  Because *Note `mysql_stmt_affected_rows()':
mysql-stmt-affected-rows.  returns an unsigned value, you can check for
-1 by comparing the return value to `(my_ulonglong)-1' (or to
`(my_ulonglong)~0', which is equivalent).

See *Note mysql-affected-rows::, for additional information on the
return value.

*Errors*

None.

*Example*

For the usage of *Note `mysql_stmt_affected_rows()':
mysql-stmt-affected-rows, refer to the Example from *Note
mysql-stmt-execute::.


File: manual.info,  Node: mysql-stmt-attr-get,  Next: mysql-stmt-attr-set,  Prev: mysql-stmt-affected-rows,  Up: c-api-prepared-statement-functions

29.2.7.2 *Note `mysql_stmt_attr_get()': mysql-stmt-attr-get.
............................................................

`my_bool mysql_stmt_attr_get(MYSQL_STMT *stmt, enum enum_stmt_attr_type
option, void *arg)'

*Description*

Can be used to get the current value for a statement attribute.

The `option' argument is the option that you want to get; the `arg'
should point to a variable that should contain the option value. If the
option is an integer, then `arg' should point to the value of the
integer.

See *Note mysql-stmt-attr-set::, for a list of options and option types.

*Note*:

In MySQL 5.1, *Note `mysql_stmt_attr_get()': mysql-stmt-attr-get.
originally used `unsigned int *', not `my_bool *', for
`STMT_ATTR_UPDATE_MAX_LENGTH'. This was corrected in MySQL 5.1.7.

*Return Values*

Zero if successful. Non-zero if `option' is unknown.

*Errors*

None.


File: manual.info,  Node: mysql-stmt-attr-set,  Next: mysql-stmt-bind-param,  Prev: mysql-stmt-attr-get,  Up: c-api-prepared-statement-functions

29.2.7.3 *Note `mysql_stmt_attr_set()': mysql-stmt-attr-set.
............................................................

`my_bool mysql_stmt_attr_set(MYSQL_STMT *stmt, enum enum_stmt_attr_type
option, const void *arg)'

*Description*

Can be used to affect behavior for a prepared statement. This function
may be called multiple times to set several options.

The `option' argument is the option that you want to set. The `arg'
argument is the value for the option. `arg' should point to a variable
that is set to the desired attribute value. The variable type is as
indicated in the following table.

Possible `option' values:

*Option*                       *Argument      *Function*
                               Type*          
`STMT_ATTR_UPDATE_MAX_LENGTH'  `my_bool *'    If set to 1: Update
                                              metadata
                                              `MYSQL_FIELD->max_length'
                                              in *Note
                                              `mysql_stmt_store_result()':
                                              mysql-stmt-store-result.
`STMT_ATTR_CURSOR_TYPE'        `unsigned      Type of cursor to open for
                               long *'        statement when *Note
                                              `mysql_stmt_execute()':
                                              mysql-stmt-execute. is
                                              invoked. `*arg' can be
                                              `CURSOR_TYPE_NO_CURSOR'
                                              (the default) or
                                              `CURSOR_TYPE_READ_ONLY'.
`STMT_ATTR_PREFETCH_ROWS'      `unsigned      Number of rows to fetch
                               long *'        from server at a time when
                                              using a cursor.  `*arg'
                                              can be in the range from 1
                                              to the maximum value of
                                              `unsigned long'.  The
                                              default is 1.

If you use the `STMT_ATTR_CURSOR_TYPE' option with
`CURSOR_TYPE_READ_ONLY', a cursor is opened for the statement when you
invoke *Note `mysql_stmt_execute()': mysql-stmt-execute. If there is
already an open cursor from a previous *Note `mysql_stmt_execute()':
mysql-stmt-execute. call, it closes the cursor before opening a new one.
*Note `mysql_stmt_reset()': mysql-stmt-reset. also closes any open
cursor before preparing the statement for re-execution.  *Note
`mysql_stmt_free_result()': mysql-stmt-free-result. closes any open
cursor.

If you open a cursor for a prepared statement, *Note
`mysql_stmt_store_result()': mysql-stmt-store-result. is unnecessary,
because that function causes the result set to be buffered on the
client side.

*Return Values*

Zero if successful. Non-zero if `option' is unknown.

*Errors*

None.

*Example*

The following example opens a cursor for a prepared statement and sets
the number of rows to fetch at a time to 5:

     MYSQL_STMT *stmt;
     int rc;
     unsigned long type;
     unsigned long prefetch_rows = 5;

     stmt = mysql_stmt_init(mysql);
     type = (unsigned long) CURSOR_TYPE_READ_ONLY;
     rc = mysql_stmt_attr_set(stmt, STMT_ATTR_CURSOR_TYPE, (void*) &type);
     /* ... check return value ... */
     rc = mysql_stmt_attr_set(stmt, STMT_ATTR_PREFETCH_ROWS,
                              (void*) &prefetch_rows);
     /* ... check return value ... */


File: manual.info,  Node: mysql-stmt-bind-param,  Next: mysql-stmt-bind-result,  Prev: mysql-stmt-attr-set,  Up: c-api-prepared-statement-functions

29.2.7.4 *Note `mysql_stmt_bind_param()': mysql-stmt-bind-param.
................................................................

`my_bool mysql_stmt_bind_param(MYSQL_STMT *stmt, MYSQL_BIND *bind)'

*Description*

*Note `mysql_stmt_bind_param()': mysql-stmt-bind-param. is used to bind
input data for the parameter markers in the SQL statement that was
passed to *Note `mysql_stmt_prepare()': mysql-stmt-prepare. It uses
`MYSQL_BIND' structures to supply the data.  `bind' is the address of
an array of `MYSQL_BIND' structures. The client library expects the
array to contain one element for each ``?'' parameter marker that is
present in the query.

Suppose that you prepare the following statement:

     INSERT INTO mytbl VALUES(?,?,?)

When you bind the parameters, the array of `MYSQL_BIND' structures must
contain three elements, and can be declared like this:

     MYSQL_BIND bind[3];

*Note c-api-prepared-statement-datatypes::, describes the members of
each `MYSQL_BIND' element and how they should be set to provide input
values.

*Return Values*

Zero if the bind operation was successful. Non-zero if an error
occurred.

*Errors*

   * `CR_UNSUPPORTED_PARAM_TYPE'

     The conversion is not supported. Possibly the `buffer_type' value
     is illegal or is not one of the supported types.

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

*Example*

For the usage of *Note `mysql_stmt_bind_param()':
mysql-stmt-bind-param, refer to the Example from *Note
mysql-stmt-execute::.


File: manual.info,  Node: mysql-stmt-bind-result,  Next: mysql-stmt-close,  Prev: mysql-stmt-bind-param,  Up: c-api-prepared-statement-functions

29.2.7.5 *Note `mysql_stmt_bind_result()': mysql-stmt-bind-result.
..................................................................

`my_bool mysql_stmt_bind_result(MYSQL_STMT *stmt, MYSQL_BIND *bind)'

*Description*

*Note `mysql_stmt_bind_result()': mysql-stmt-bind-result. is used to
associate (that is, bind) output columns in the result set to data
buffers and length buffers. When *Note `mysql_stmt_fetch()':
mysql-stmt-fetch. is called to fetch data, the MySQL client/server
protocol places the data for the bound columns into the specified
buffers.

All columns must be bound to buffers prior to calling *Note
`mysql_stmt_fetch()': mysql-stmt-fetch.  `bind' is the address of an
array of `MYSQL_BIND' structures. The client library expects the array
to contain one element for each column of the result set. If you do not
bind columns to `MYSQL_BIND' structures, *Note `mysql_stmt_fetch()':
mysql-stmt-fetch. simply ignores the data fetch. The buffers should be
large enough to hold the data values, because the protocol doesn't
return data values in chunks.

A column can be bound or rebound at any time, even after a result set
has been partially retrieved. The new binding takes effect the next time
*Note `mysql_stmt_fetch()': mysql-stmt-fetch. is called.  Suppose that
an application binds the columns in a result set and calls *Note
`mysql_stmt_fetch()': mysql-stmt-fetch.  The client/server protocol
returns data in the bound buffers.  Then suppose that the application
binds the columns to a different set of buffers. The protocol places
data into the newly bound buffers when the next call to *Note
`mysql_stmt_fetch()': mysql-stmt-fetch. occurs.

To bind a column, an application calls *Note
`mysql_stmt_bind_result()': mysql-stmt-bind-result. and passes the
type, address, and length of the output buffer into which the value
should be stored.  *Note c-api-prepared-statement-datatypes::, describes
the members of each `MYSQL_BIND' element and how they should be set to
receive output values.

*Return Values*

Zero if the bind operation was successful. Non-zero if an error
occurred.

*Errors*

   * `CR_UNSUPPORTED_PARAM_TYPE'

     The conversion is not supported. Possibly the `buffer_type' value
     is illegal or is not one of the supported types.

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

*Example*

For the usage of *Note `mysql_stmt_bind_result()':
mysql-stmt-bind-result, refer to the Example from *Note
mysql-stmt-fetch::.


File: manual.info,  Node: mysql-stmt-close,  Next: mysql-stmt-data-seek,  Prev: mysql-stmt-bind-result,  Up: c-api-prepared-statement-functions

29.2.7.6 *Note `mysql_stmt_close()': mysql-stmt-close.
......................................................

`my_bool mysql_stmt_close(MYSQL_STMT *)'

*Description*

Closes the prepared statement.  *Note `mysql_stmt_close()':
mysql-stmt-close. also deallocates the statement handle pointed to by
`stmt'.

If the current statement has pending or unread results, this function
cancels them so that the next query can be executed.

*Return Values*

Zero if the statement was freed successfully. Non-zero if an error
occurred.

*Errors*

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

*Example*

For the usage of *Note `mysql_stmt_close()': mysql-stmt-close, refer to
the Example from *Note mysql-stmt-execute::.


File: manual.info,  Node: mysql-stmt-data-seek,  Next: mysql-stmt-errno,  Prev: mysql-stmt-close,  Up: c-api-prepared-statement-functions

29.2.7.7 *Note `mysql_stmt_data_seek()': mysql-stmt-data-seek.
..............................................................

`void mysql_stmt_data_seek(MYSQL_STMT *stmt, my_ulonglong offset)'

*Description*

Seeks to an arbitrary row in a statement result set. The `offset' value
is a row number and should be in the range from `0' to *Note
`mysql_stmt_num_rows(stmt)-1': mysql-stmt-num-rows.

This function requires that the statement result set structure contains
the entire result of the last executed query, so *Note
`mysql_stmt_data_seek()': mysql-stmt-data-seek. may be used only in
conjunction with *Note `mysql_stmt_store_result()':
mysql-stmt-store-result.

*Return Values*

None.

*Errors*

None.


File: manual.info,  Node: mysql-stmt-errno,  Next: mysql-stmt-error,  Prev: mysql-stmt-data-seek,  Up: c-api-prepared-statement-functions

29.2.7.8 *Note `mysql_stmt_errno()': mysql-stmt-errno.
......................................................

`unsigned int mysql_stmt_errno(MYSQL_STMT *stmt)'

*Description*

For the statement specified by `stmt', *Note `mysql_stmt_errno()':
mysql-stmt-errno. returns the error code for the most recently invoked
statement API function that can succeed or fail. A return value of zero
means that no error occurred. Client error message numbers are listed
in the MySQL `errmsg.h' header file. Server error message numbers are
listed in `mysqld_error.h'. Errors also are listed at *Note
error-handling::.

*Return Values*

An error code value. Zero if no error occurred.

*Errors*

None.


File: manual.info,  Node: mysql-stmt-error,  Next: mysql-stmt-execute,  Prev: mysql-stmt-errno,  Up: c-api-prepared-statement-functions

29.2.7.9 *Note `mysql_stmt_error()': mysql-stmt-error.
......................................................

`const char *mysql_stmt_error(MYSQL_STMT *stmt)'

*Description*

For the statement specified by `stmt', *Note `mysql_stmt_error()':
mysql-stmt-error. returns a null-terminated string containing the error
message for the most recently invoked statement API function that can
succeed or fail. An empty string (`""') is returned if no error
occurred. This means the following two tests are equivalent:

     if(*mysql_stmt_errno(stmt))
     {
       // an error occurred
     }

     if (mysql_stmt_error(stmt)[0])
     {
       // an error occurred
     }

The language of the client error messages may be changed by recompiling
the MySQL client library. Currently, you can choose error messages in
several different languages.

*Return Values*

A character string that describes the error. An empty string if no
error occurred.

*Errors*

None.


File: manual.info,  Node: mysql-stmt-execute,  Next: mysql-stmt-fetch,  Prev: mysql-stmt-error,  Up: c-api-prepared-statement-functions

29.2.7.10 *Note `mysql_stmt_execute()': mysql-stmt-execute.
...........................................................

`int mysql_stmt_execute(MYSQL_STMT *stmt)'

*Description*

*Note `mysql_stmt_execute()': mysql-stmt-execute. executes the prepared
query associated with the statement handle. The currently bound
parameter marker values are sent to server during this call, and the
server replaces the markers with this newly supplied data.

If the statement is an `UPDATE', `DELETE', or `INSERT', the total
number of changed, deleted, or inserted rows can be found by calling
*Note `mysql_stmt_affected_rows()': mysql-stmt-affected-rows. If this
is a statement such as `SELECT' that generates a result set, you must
call *Note `mysql_stmt_fetch()': mysql-stmt-fetch. to fetch the data
prior to calling any other functions that result in query processing.
For more information on how to fetch the results, refer to *Note
mysql-stmt-fetch::.

For statements that generate a result set, you can request that *Note
`mysql_stmt_execute()': mysql-stmt-execute. open a cursor for the
statement by calling *Note `mysql_stmt_attr_set()':
mysql-stmt-attr-set. before executing the statement. If you execute a
statement multiple times, *Note `mysql_stmt_execute()':
mysql-stmt-execute.  closes any open cursor before opening a new one.

As of MySQL 5.1.25, metadata changes to tables or views referred to by
prepared statements are detected and cause automatic repreparation of
the statement when it is next executed. For more information, see *Note
statement-repreparation::.

*Return Values*

Zero if execution was successful. Non-zero if an error occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

*Example*

The following example demonstrates how to create and populate a table
using *Note `mysql_stmt_init()': mysql-stmt-init, *Note
`mysql_stmt_prepare()': mysql-stmt-prepare, *Note
`mysql_stmt_param_count()': mysql-stmt-param-count, *Note
`mysql_stmt_bind_param()': mysql-stmt-bind-param, *Note
`mysql_stmt_execute()': mysql-stmt-execute, and *Note
`mysql_stmt_affected_rows()': mysql-stmt-affected-rows. The `mysql'
variable is assumed to be a valid connection handle.

     #define STRING_SIZE 50

     #define DROP_SAMPLE_TABLE "DROP TABLE IF EXISTS test_table"
     #define CREATE_SAMPLE_TABLE "CREATE TABLE test_table(col1 INT,\
                                                      col2 VARCHAR(40),\
                                                      col3 SMALLINT,\
                                                      col4 TIMESTAMP)"
     #define INSERT_SAMPLE "INSERT INTO \
                            test_table(col1,col2,col3) \
                            VALUES(?,?,?)"

     MYSQL_STMT    *stmt;
     MYSQL_BIND    bind[3];
     my_ulonglong  affected_rows;
     int           param_count;
     short         small_data;
     int           int_data;
     char          str_data[STRING_SIZE];
     unsigned long str_length;
     my_bool       is_null;

     if (mysql_query(mysql, DROP_SAMPLE_TABLE))
     {
       fprintf(stderr, " DROP TABLE failed\n");
       fprintf(stderr, " %s\n", mysql_error(mysql));
       exit(0);
     }

     if (mysql_query(mysql, CREATE_SAMPLE_TABLE))
     {
       fprintf(stderr, " CREATE TABLE failed\n");
       fprintf(stderr, " %s\n", mysql_error(mysql));
       exit(0);
     }

     /* Prepare an INSERT query with 3 parameters */
     /* (the TIMESTAMP column is not named; the server */
     /*  sets it to the current date and time) */
     stmt = mysql_stmt_init(mysql);
     if (!stmt)
     {
       fprintf(stderr, " mysql_stmt_init(), out of memory\n");
       exit(0);
     }
     if (mysql_stmt_prepare(stmt, INSERT_SAMPLE, strlen(INSERT_SAMPLE)))
     {
       fprintf(stderr, " mysql_stmt_prepare(), INSERT failed\n");
       fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
       exit(0);
     }
     fprintf(stdout, " prepare, INSERT successful\n");

     /* Get the parameter count from the statement */
     param_count= mysql_stmt_param_count(stmt);
     fprintf(stdout, " total parameters in INSERT: %d\n", param_count);

     if (param_count != 3) /* validate parameter count */
     {
       fprintf(stderr, " invalid parameter count returned by MySQL\n");
       exit(0);
     }

     /* Bind the data for all 3 parameters */

     memset(bind, 0, sizeof(bind));

     /* INTEGER PARAM */
     /* This is a number type, so there is no need
        to specify buffer_length */
     bind[0].buffer_type= MYSQL_TYPE_LONG;
     bind[0].buffer= (char *)&int_data;
     bind[0].is_null= 0;
     bind[0].length= 0;

     /* STRING PARAM */
     bind[1].buffer_type= MYSQL_TYPE_STRING;
     bind[1].buffer= (char *)str_data;
     bind[1].buffer_length= STRING_SIZE;
     bind[1].is_null= 0;
     bind[1].length= &str_length;

     /* SMALLINT PARAM */
     bind[2].buffer_type= MYSQL_TYPE_SHORT;
     bind[2].buffer= (char *)&small_data;
     bind[2].is_null= &is_null;
     bind[2].length= 0;

     /* Bind the buffers */
     if (mysql_stmt_bind_param(stmt, bind))
     {
       fprintf(stderr, " mysql_stmt_bind_param() failed\n");
       fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
       exit(0);
     }

     /* Specify the data values for the first row */
     int_data= 10;             /* integer */
     strncpy(str_data, "MySQL", STRING_SIZE); /* string  */
     str_length= strlen(str_data);

     /* INSERT SMALLINT data as NULL */
     is_null= 1;

     /* Execute the INSERT statement - 1*/
     if (mysql_stmt_execute(stmt))
     {
       fprintf(stderr, " mysql_stmt_execute(), 1 failed\n");
       fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
       exit(0);
     }

     /* Get the total number of affected rows */
     affected_rows= mysql_stmt_affected_rows(stmt);
     fprintf(stdout, " total affected rows(insert 1): %lu\n",
                     (unsigned long) affected_rows);

     if (affected_rows != 1) /* validate affected rows */
     {
       fprintf(stderr, " invalid affected rows by MySQL\n");
       exit(0);
     }

     /* Specify data values for second row,
        then re-execute the statement */
     int_data= 1000;
     strncpy(str_data, "
             The most popular Open Source database",
             STRING_SIZE);
     str_length= strlen(str_data);
     small_data= 1000;         /* smallint */
     is_null= 0;               /* reset */

     /* Execute the INSERT statement - 2*/
     if (mysql_stmt_execute(stmt))
     {
       fprintf(stderr, " mysql_stmt_execute, 2 failed\n");
       fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
       exit(0);
     }

     /* Get the total rows affected */
     affected_rows= mysql_stmt_affected_rows(stmt);
     fprintf(stdout, " total affected rows(insert 2): %lu\n",
                     (unsigned long) affected_rows);

     if (affected_rows != 1) /* validate affected rows */
     {
       fprintf(stderr, " invalid affected rows by MySQL\n");
       exit(0);
     }

     /* Close the statement */
     if (mysql_stmt_close(stmt))
     {
       fprintf(stderr, " failed while closing the statement\n");
       fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
       exit(0);
     }

*Note*:

For complete examples on the use of prepared statement functions, refer
to the file `tests/mysql_client_test.c'. This file can be obtained from
a MySQL source distribution or from the Bazaar source repository.


File: manual.info,  Node: mysql-stmt-fetch,  Next: mysql-stmt-fetch-column,  Prev: mysql-stmt-execute,  Up: c-api-prepared-statement-functions

29.2.7.11 *Note `mysql_stmt_fetch()': mysql-stmt-fetch.
.......................................................

`int mysql_stmt_fetch(MYSQL_STMT *stmt)'

*Description*

*Note `mysql_stmt_fetch()': mysql-stmt-fetch. returns the next row in
the result set. It can be called only while the result set exists; that
is, after a call to *Note `mysql_stmt_execute()': mysql-stmt-execute.
for a statement such as `SELECT' that creates a result set.

*Note `mysql_stmt_fetch()': mysql-stmt-fetch. returns row data using
the buffers bound by *Note `mysql_stmt_bind_result()':
mysql-stmt-bind-result. It returns the data in those buffers for all
the columns in the current row set and the lengths are returned to the
`length' pointer. All columns must be bound by the application before
it calls *Note `mysql_stmt_fetch()': mysql-stmt-fetch.

By default, result sets are fetched unbuffered a row at a time from the
server. To buffer the entire result set on the client, call *Note
`mysql_stmt_store_result()': mysql-stmt-store-result.  after binding
the data buffers and before caling *Note `mysql_stmt_fetch()':
mysql-stmt-fetch.

If a fetched data value is a `NULL' value, the `*is_null' value of the
corresponding `MYSQL_BIND' structure contains TRUE (1).  Otherwise, the
data and its length are returned in the `*buffer' and `*length'
elements based on the buffer type specified by the application.  Each
numeric and temporal type has a fixed length, as listed in the
following table. The length of the string types depends on the length
of the actual data value, as indicated by `data_length'.

*Type*                               *Length*
`MYSQL_TYPE_TINY'                    1
`MYSQL_TYPE_SHORT'                   2
`MYSQL_TYPE_LONG'                    4
`MYSQL_TYPE_LONGLONG'                8
`MYSQL_TYPE_FLOAT'                   4
`MYSQL_TYPE_DOUBLE'                  8
`MYSQL_TYPE_TIME'                    `sizeof(MYSQL_TIME)'
`MYSQL_TYPE_DATE'                    `sizeof(MYSQL_TIME)'
`MYSQL_TYPE_DATETIME'                `sizeof(MYSQL_TIME)'
`MYSQL_TYPE_STRING'                  `data length'
`MYSQL_TYPE_BLOB'                    `data_length'

*Return Values*

*Return Value*            *Description*
0                         Successful, the data has been fetched to
                          application data buffers.
1                         Error occurred. Error code and message can be
                          obtained by calling *Note
                          `mysql_stmt_errno()': mysql-stmt-errno. and
                          *Note `mysql_stmt_error()': mysql-stmt-error.
`MYSQL_NO_DATA'           No more rows/data exists
`MYSQL_DATA_TRUNCATED'    Data truncation occurred

`MYSQL_DATA_TRUNCATED' is returned when truncation reporting is
enabled. (Reporting is enabled by default, but can be controlled with
*Note `mysql_options()': mysql-options.) To determine which parameters
were truncated when this value is returned, check the `error' members
of the `MYSQL_BIND' parameter structures.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

   * `CR_UNSUPPORTED_PARAM_TYPE'

     The buffer type is `MYSQL_TYPE_DATE', `MYSQL_TYPE_TIME',
     `MYSQL_TYPE_DATETIME', or `MYSQL_TYPE_TIMESTAMP', but the data type
     is not `DATE', `TIME', `DATETIME', or `TIMESTAMP'.

   * All other unsupported conversion errors are returned from *Note
     `mysql_stmt_bind_result()': mysql-stmt-bind-result.

*Example*

The following example demonstrates how to fetch data from a table using
*Note `mysql_stmt_result_metadata()': mysql-stmt-result-metadata, *Note
`mysql_stmt_bind_result()': mysql-stmt-bind-result, and *Note
`mysql_stmt_fetch()': mysql-stmt-fetch. (This example expects to
retrieve the two rows inserted by the example shown in *Note
mysql-stmt-execute::.) The `mysql' variable is assumed to be a valid
connection handle.

     #define STRING_SIZE 50

     #define SELECT_SAMPLE "SELECT col1, col2, col3, col4 \
                            FROM test_table"

     MYSQL_STMT    *stmt;
     MYSQL_BIND    bind[4];
     MYSQL_RES     *prepare_meta_result;
     MYSQL_TIME    ts;
     unsigned long length[4];
     int           param_count, column_count, row_count;
     short         small_data;
     int           int_data;
     char          str_data[STRING_SIZE];
     my_bool       is_null[4];
     my_bool       error[4];

     /* Prepare a SELECT query to fetch data from test_table */
     stmt = mysql_stmt_init(mysql);
     if (!stmt)
     {
       fprintf(stderr, " mysql_stmt_init(), out of memory\n");
       exit(0);
     }
     if (mysql_stmt_prepare(stmt, SELECT_SAMPLE, strlen(SELECT_SAMPLE)))
     {
       fprintf(stderr, " mysql_stmt_prepare(), SELECT failed\n");
       fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
       exit(0);
     }
     fprintf(stdout, " prepare, SELECT successful\n");

     /* Get the parameter count from the statement */
     param_count= mysql_stmt_param_count(stmt);
     fprintf(stdout, " total parameters in SELECT: %d\n", param_count);

     if (param_count != 0) /* validate parameter count */
     {
       fprintf(stderr, " invalid parameter count returned by MySQL\n");
       exit(0);
     }

     /* Fetch result set meta information */
     prepare_meta_result = mysql_stmt_result_metadata(stmt);
     if (!prepare_meta_result)
     {
       fprintf(stderr,
              " mysql_stmt_result_metadata(), \
                returned no meta information\n");
       fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
       exit(0);
     }

     /* Get total columns in the query */
     column_count= mysql_num_fields(prepare_meta_result);
     fprintf(stdout,
             " total columns in SELECT statement: %d\n",
             column_count);

     if (column_count != 4) /* validate column count */
     {
       fprintf(stderr, " invalid column count returned by MySQL\n");
       exit(0);
     }

     /* Execute the SELECT query */
     if (mysql_stmt_execute(stmt))
     {
       fprintf(stderr, " mysql_stmt_execute(), failed\n");
       fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
       exit(0);
     }

     /* Bind the result buffers for all 4 columns before fetching them */

     memset(bind, 0, sizeof(bind));

     /* INTEGER COLUMN */
     bind[0].buffer_type= MYSQL_TYPE_LONG;
     bind[0].buffer= (char *)&int_data;
     bind[0].is_null= &is_null[0];
     bind[0].length= &length[0];
     bind[0].error= &error[0];

     /* STRING COLUMN */
     bind[1].buffer_type= MYSQL_TYPE_STRING;
     bind[1].buffer= (char *)str_data;
     bind[1].buffer_length= STRING_SIZE;
     bind[1].is_null= &is_null[1];
     bind[1].length= &length[1];
     bind[1].error= &error[1];

     /* SMALLINT COLUMN */
     bind[2].buffer_type= MYSQL_TYPE_SHORT;
     bind[2].buffer= (char *)&small_data;
     bind[2].is_null= &is_null[2];
     bind[2].length= &length[2];
     bind[2].error= &error[2];

     /* TIMESTAMP COLUMN */
     bind[3].buffer_type= MYSQL_TYPE_TIMESTAMP;
     bind[3].buffer= (char *)&ts;
     bind[3].is_null= &is_null[3];
     bind[3].length= &length[3];
     bind[3].error= &error[3];

     /* Bind the result buffers */
     if (mysql_stmt_bind_result(stmt, bind))
     {
       fprintf(stderr, " mysql_stmt_bind_result() failed\n");
       fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
       exit(0);
     }

     /* Now buffer all results to client (optional step) */
     if (mysql_stmt_store_result(stmt))
     {
       fprintf(stderr, " mysql_stmt_store_result() failed\n");
       fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
       exit(0);
     }

     /* Fetch all rows */
     row_count= 0;
     fprintf(stdout, "Fetching results ...\n");
     while (!mysql_stmt_fetch(stmt))
     {
       row_count++;
       fprintf(stdout, "  row %d\n", row_count);

       /* column 1 */
       fprintf(stdout, "   column1 (integer)  : ");
       if (is_null[0])
         fprintf(stdout, " NULL\n");
       else
         fprintf(stdout, " %d(%ld)\n", int_data, length[0]);

       /* column 2 */
       fprintf(stdout, "   column2 (string)   : ");
       if (is_null[1])
         fprintf(stdout, " NULL\n");
       else
         fprintf(stdout, " %s(%ld)\n", str_data, length[1]);

       /* column 3 */
       fprintf(stdout, "   column3 (smallint) : ");
       if (is_null[2])
         fprintf(stdout, " NULL\n");
       else
         fprintf(stdout, " %d(%ld)\n", small_data, length[2]);

       /* column 4 */
       fprintf(stdout, "   column4 (timestamp): ");
       if (is_null[3])
         fprintf(stdout, " NULL\n");
       else
         fprintf(stdout, " %04d-%02d-%02d %02d:%02d:%02d (%ld)\n",
                          ts.year, ts.month, ts.day,
                          ts.hour, ts.minute, ts.second,
                          length[3]);
       fprintf(stdout, "\n");
     }

     /* Validate rows fetched */
     fprintf(stdout, " total rows fetched: %d\n", row_count);
     if (row_count != 2)
     {
       fprintf(stderr, " MySQL failed to return all rows\n");
       exit(0);
     }

     /* Free the prepared result metadata */
     mysql_free_result(prepare_meta_result);

     /* Close the statement */
     if (mysql_stmt_close(stmt))
     {
       fprintf(stderr, " failed while closing the statement\n");
       fprintf(stderr, " %s\n", mysql_stmt_error(stmt));
       exit(0);
     }

In some cases you might want to determine the length of a column value
before fetching it with *Note `mysql_stmt_fetch()': mysql-stmt-fetch.
For example, the value might be a long string or `BLOB' value for which
you want to know how much space must be allocated. To accomplish this,
you can use these strategies:

   * Before invoking *Note `mysql_stmt_fetch()': mysql-stmt-fetch. to
     retrieve individual rows, invoke *Note
     `mysql_stmt_store_result()': mysql-stmt-store-result.  to buffer
     the entire result on the client side. Then the maximal length of
     column values will be indicated by the `max_length' member of the
     result set metadata returned by *Note
     `mysql_stmt_result_metadata()': mysql-stmt-result-metadata.  This
     strategy requires that you pass `STMT_ATTR_UPDATE_MAX_LENGTH' to
     *Note `mysql_stmt_attr_set()': mysql-stmt-attr-set. or the
     `max_length' values will not be calculated.

   * Invoke *Note `mysql_stmt_fetch()': mysql-stmt-fetch.  with a
     zero-length buffer for the column in question and a pointer in
     which the real length can be stored. Then use the real length with
     *Note `mysql_stmt_fetch_column()': mysql-stmt-fetch-column.

          real_length= 0;

          bind[0].buffer= 0;
          bind[0].buffer_length= 0;
          bind[0].length= &real_length
          mysql_stmt_bind_result(stmt, bind);

          mysql_stmt_fetch(stmt);
          if (real_length > 0)
          {
            data= malloc(real_length);
            bind[0].buffer= data;
            bind[0].buffer_length= real_length;
            mysql_stmt_fetch_column(stmt, 0, bind, 0);
          }


File: manual.info,  Node: mysql-stmt-fetch-column,  Next: mysql-stmt-field-count,  Prev: mysql-stmt-fetch,  Up: c-api-prepared-statement-functions

29.2.7.12 *Note `mysql_stmt_fetch_column()': mysql-stmt-fetch-column.
.....................................................................

`int mysql_stmt_fetch_column(MYSQL_STMT *stmt, MYSQL_BIND *bind,
unsigned int column, unsigned long offset)'

*Description*

Fetch one column from the current result set row.  `bind' provides the
buffer where data should be placed. It should be set up the same way as
for *Note `mysql_stmt_bind_result()': mysql-stmt-bind-result.  `column'
indicates which column to fetch. The first column is numbered 0.
`offset' is the offset within the data value at which to begin
retrieving data.  This can be used for fetching the data value in
pieces. The beginning of the value is offset 0.

As of MySQL 5.1.25, metadata changes to tables or views referred to by
prepared statements are detected and cause automatic repreparation of
the statement when it is next executed. For more information, see *Note
statement-repreparation::.

*Return Values*

Zero if the value was fetched successfully. Non-zero if an error
occurred.

*Errors*

   * `CR_INVALID_PARAMETER_NO'

     Invalid column number.

   * `CR_NO_DATA'

     The end of the result set has already been reached.


File: manual.info,  Node: mysql-stmt-field-count,  Next: mysql-stmt-free-result,  Prev: mysql-stmt-fetch-column,  Up: c-api-prepared-statement-functions

29.2.7.13 *Note `mysql_stmt_field_count()': mysql-stmt-field-count.
...................................................................

`unsigned int mysql_stmt_field_count(MYSQL_STMT *stmt)'

*Description*

Returns the number of columns for the most recent statement for the
statement handler. This value is zero for statements such as `INSERT'
or `DELETE' that do not produce result sets.

*Note `mysql_stmt_field_count()': mysql-stmt-field-count. can be called
after you have prepared a statement by invoking *Note
`mysql_stmt_prepare()': mysql-stmt-prepare.

*Return Values*

An unsigned integer representing the number of columns in a result set.

*Errors*

None.


File: manual.info,  Node: mysql-stmt-free-result,  Next: mysql-stmt-init,  Prev: mysql-stmt-field-count,  Up: c-api-prepared-statement-functions

29.2.7.14 *Note `mysql_stmt_free_result()': mysql-stmt-free-result.
...................................................................

`my_bool mysql_stmt_free_result(MYSQL_STMT *stmt)'

*Description*

Releases memory associated with the result set produced by execution of
the prepared statement. If there is a cursor open for the statement,
*Note `mysql_stmt_free_result()': mysql-stmt-free-result. closes it.

*Return Values*

Zero if the result set was freed successfully. Non-zero if an error
occurred.

*Errors*


File: manual.info,  Node: mysql-stmt-init,  Next: mysql-stmt-insert-id,  Prev: mysql-stmt-free-result,  Up: c-api-prepared-statement-functions

29.2.7.15 *Note `mysql_stmt_init()': mysql-stmt-init.
.....................................................

`MYSQL_STMT *mysql_stmt_init(MYSQL *mysql)'

*Description*

Create a `MYSQL_STMT' handle. The handle should be freed with *Note
`mysql_stmt_close(MYSQL_STMT *)': mysql-stmt-close.

*Return values*

A pointer to a `MYSQL_STMT' structure in case of success. `NULL' if out
of memory.

*Errors*

   * `CR_OUT_OF_MEMORY'

     Out of memory.


File: manual.info,  Node: mysql-stmt-insert-id,  Next: mysql-stmt-num-rows,  Prev: mysql-stmt-init,  Up: c-api-prepared-statement-functions

29.2.7.16 *Note `mysql_stmt_insert_id()': mysql-stmt-insert-id.
...............................................................

`my_ulonglong mysql_stmt_insert_id(MYSQL_STMT *stmt)'

*Description*

Returns the value generated for an `AUTO_INCREMENT' column by the
prepared `INSERT' or `UPDATE' statement. Use this function after you
have executed a prepared `INSERT' statement on a table which contains an
`AUTO_INCREMENT' field.

See *Note mysql-insert-id::, for more information.

*Return Values*

Value for `AUTO_INCREMENT' column which was automatically generated or
explicitly set during execution of prepared statement, or value
generated by `LAST_INSERT_ID(EXPR)' function. Return value is undefined
if statement does not set `AUTO_INCREMENT' value.

*Errors*

None.


File: manual.info,  Node: mysql-stmt-num-rows,  Next: mysql-stmt-param-count,  Prev: mysql-stmt-insert-id,  Up: c-api-prepared-statement-functions

29.2.7.17 *Note `mysql_stmt_num_rows()': mysql-stmt-num-rows.
.............................................................

`my_ulonglong mysql_stmt_num_rows(MYSQL_STMT *stmt)'

*Description*

Returns the number of rows in the result set.

The use of *Note `mysql_stmt_num_rows()': mysql-stmt-num-rows. depends
on whether you used *Note `mysql_stmt_store_result()':
mysql-stmt-store-result. to buffer the entire result set in the
statement handle.

If you use *Note `mysql_stmt_store_result()': mysql-stmt-store-result,
*Note `mysql_stmt_num_rows()': mysql-stmt-num-rows. may be called
immediately. Otherwise, the row count is unavailable unless you count
the rows as you fetch them.

*Note `mysql_stmt_num_rows()': mysql-stmt-num-rows. is intended for use
with statements that return a result set, such as `SELECT'. For
statements such as `INSERT', `UPDATE', or `DELETE', the number of
affected rows can be obtained with *Note `mysql_stmt_affected_rows()':
mysql-stmt-affected-rows.

*Return Values*

The number of rows in the result set.

*Errors*

None.


File: manual.info,  Node: mysql-stmt-param-count,  Next: mysql-stmt-param-metadata,  Prev: mysql-stmt-num-rows,  Up: c-api-prepared-statement-functions

29.2.7.18 *Note `mysql_stmt_param_count()': mysql-stmt-param-count.
...................................................................

`unsigned long mysql_stmt_param_count(MYSQL_STMT *stmt)'

*Description*

Returns the number of parameter markers present in the prepared
statement.

*Return Values*

An unsigned long integer representing the number of parameters in a
statement.

*Errors*

None.

*Example*

For the usage of *Note `mysql_stmt_param_count()':
mysql-stmt-param-count, refer to the Example from *Note
mysql-stmt-execute::.


File: manual.info,  Node: mysql-stmt-param-metadata,  Next: mysql-stmt-prepare,  Prev: mysql-stmt-param-count,  Up: c-api-prepared-statement-functions

29.2.7.19 *Note `mysql_stmt_param_metadata()': mysql-stmt-param-metadata.
.........................................................................

`MYSQL_RES *mysql_stmt_param_metadata(MYSQL_STMT *stmt)'

This function currently does nothing.

*Description*

*Return Values*

*Errors*


File: manual.info,  Node: mysql-stmt-prepare,  Next: mysql-stmt-reset,  Prev: mysql-stmt-param-metadata,  Up: c-api-prepared-statement-functions

29.2.7.20 *Note `mysql_stmt_prepare()': mysql-stmt-prepare.
...........................................................

`int mysql_stmt_prepare(MYSQL_STMT *stmt, const char *stmt_str,
unsigned long length)'

*Description*

Given the statement handle returned by *Note `mysql_stmt_init()':
mysql-stmt-init, prepares the SQL statement pointed to by the string
`stmt_str' and returns a status value. The string length should be
given by the `length' argument. The string must consist of a single SQL
statement. You should not add a terminating semicolon (``;'') or `\g'
to the statement.

The application can include one or more parameter markers in the SQL
statement by embedding question mark (``?'') characters into the SQL
string at the appropriate positions.

The markers are legal only in certain places in SQL statements.  For
example, they are allowed in the `VALUES()' list of an `INSERT'
statement (to specify column values for a row), or in a comparison with
a column in a `WHERE' clause to specify a comparison value.  However,
they are not allowed for identifiers (such as table or column names),
or to specify both operands of a binary operator such as the `=' equal
sign. The latter restriction is necessary because it would be
impossible to determine the parameter type. In general, parameters are
legal only in Data Manipulation Language (DML) statements, and not in
Data Definition Language (DDL) statements.

The parameter markers must be bound to application variables using
*Note `mysql_stmt_bind_param()': mysql-stmt-bind-param.  before
executing the statement.

*Return Values*

Zero if the statement was prepared successfully. Non-zero if an error
occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

If the prepare operation was unsuccessful (that is, *Note
`mysql_stmt_prepare()': mysql-stmt-prepare. returns non-zero), the
error message can be obtained by calling *Note `mysql_stmt_error()':
mysql-stmt-error.

*Example*

For the usage of *Note `mysql_stmt_prepare()': mysql-stmt-prepare,
refer to the Example from *Note mysql-stmt-execute::.


File: manual.info,  Node: mysql-stmt-reset,  Next: mysql-stmt-result-metadata,  Prev: mysql-stmt-prepare,  Up: c-api-prepared-statement-functions

29.2.7.21 *Note `mysql_stmt_reset()': mysql-stmt-reset.
.......................................................

`my_bool mysql_stmt_reset(MYSQL_STMT *stmt)'

*Description*

Reset the prepared statement on the client and server to state after
prepare. This is mainly used to reset data sent with *Note
`mysql_stmt_send_long_data()': mysql-stmt-send-long-data.  Any open
cursor for the statement is closed.

To re-prepare the statement with another query, use *Note
`mysql_stmt_prepare()': mysql-stmt-prepare.

*Return Values*

Zero if the statement was reset successfully. Non-zero if an error
occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: mysql-stmt-result-metadata,  Next: mysql-stmt-row-seek,  Prev: mysql-stmt-reset,  Up: c-api-prepared-statement-functions

29.2.7.22 *Note `mysql_stmt_result_metadata()': mysql-stmt-result-metadata.
...........................................................................

`MYSQL_RES *mysql_stmt_result_metadata(MYSQL_STMT *stmt)'

*Description*

If a statement passed to *Note `mysql_stmt_prepare()':
mysql-stmt-prepare. is one that produces a result set, *Note
`mysql_stmt_result_metadata()': mysql-stmt-result-metadata.  returns
the result set metadata in the form of a pointer to a `MYSQL_RES'
structure that can be used to process the meta information such as
total number of fields and individual field information. This result
set pointer can be passed as an argument to any of the field-based API
functions that process result set metadata, such as:

   * *Note `mysql_num_fields()': mysql-num-fields.

   * *Note `mysql_fetch_field()': mysql-fetch-field.

   * *Note `mysql_fetch_field_direct()': mysql-fetch-field-direct.

   * *Note `mysql_fetch_fields()': mysql-fetch-fields.

   * *Note `mysql_field_count()': mysql-field-count.

   * *Note `mysql_field_seek()': mysql-field-seek.

   * *Note `mysql_field_tell()': mysql-field-tell.

   * *Note `mysql_free_result()': mysql-free-result.

The result set structure should be freed when you are done with it,
which you can do by passing it to *Note `mysql_free_result()':
mysql-free-result. This is similar to the way you free a result set
obtained from a call to *Note `mysql_store_result()':
mysql-store-result.

The result set returned by *Note `mysql_stmt_result_metadata()':
mysql-stmt-result-metadata.  contains only metadata. It does not
contain any row results. The rows are obtained by using the statement
handle with *Note `mysql_stmt_fetch()': mysql-stmt-fetch.

*Return Values*

A `MYSQL_RES' result structure.  `NULL' if no meta information exists
for the prepared query.

*Errors*

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

*Example*

For the usage of *Note `mysql_stmt_result_metadata()':
mysql-stmt-result-metadata, refer to the Example from *Note
mysql-stmt-fetch::.


File: manual.info,  Node: mysql-stmt-row-seek,  Next: mysql-stmt-row-tell,  Prev: mysql-stmt-result-metadata,  Up: c-api-prepared-statement-functions

29.2.7.23 *Note `mysql_stmt_row_seek()': mysql-stmt-row-seek.
.............................................................

`MYSQL_ROW_OFFSET mysql_stmt_row_seek(MYSQL_STMT *stmt,
MYSQL_ROW_OFFSET offset)'

*Description*

Sets the row cursor to an arbitrary row in a statement result set. The
`offset' value is a row offset that should be a value returned from
*Note `mysql_stmt_row_tell()': mysql-stmt-row-tell. or from *Note
`mysql_stmt_row_seek()': mysql-stmt-row-seek. This value is not a row
number; if you want to seek to a row within a result set by number, use
*Note `mysql_stmt_data_seek()': mysql-stmt-data-seek. instead.

This function requires that the result set structure contains the
entire result of the query, so *Note `mysql_stmt_row_seek()':
mysql-stmt-row-seek. may be used only in conjunction with *Note
`mysql_stmt_store_result()': mysql-stmt-store-result.

*Return Values*

The previous value of the row cursor. This value may be passed to a
subsequent call to *Note `mysql_stmt_row_seek()': mysql-stmt-row-seek.

*Errors*

None.


File: manual.info,  Node: mysql-stmt-row-tell,  Next: mysql-stmt-send-long-data,  Prev: mysql-stmt-row-seek,  Up: c-api-prepared-statement-functions

29.2.7.24 *Note `mysql_stmt_row_tell()': mysql-stmt-row-tell.
.............................................................

`MYSQL_ROW_OFFSET mysql_stmt_row_tell(MYSQL_STMT *stmt)'

*Description*

Returns the current position of the row cursor for the last *Note
`mysql_stmt_fetch()': mysql-stmt-fetch. This value can be used as an
argument to *Note `mysql_stmt_row_seek()': mysql-stmt-row-seek.

You should use *Note `mysql_stmt_row_tell()': mysql-stmt-row-tell. only
after *Note `mysql_stmt_store_result()': mysql-stmt-store-result.

*Return Values*

The current offset of the row cursor.

*Errors*

None.


File: manual.info,  Node: mysql-stmt-send-long-data,  Next: mysql-stmt-sqlstate,  Prev: mysql-stmt-row-tell,  Up: c-api-prepared-statement-functions

29.2.7.25 *Note `mysql_stmt_send_long_data()': mysql-stmt-send-long-data.
.........................................................................

`my_bool mysql_stmt_send_long_data(MYSQL_STMT *stmt, unsigned int
parameter_number, const char *data, unsigned long length)'

*Description*

Allows an application to send parameter data to the server in pieces
(or `chunks'). Call this function after *Note
`mysql_stmt_bind_param()': mysql-stmt-bind-param. and before *Note
`mysql_stmt_execute()': mysql-stmt-execute. It can be called multiple
times to send the parts of a character or binary data value for a
column, which must be one of the `TEXT' or `BLOB' data types.

`parameter_number' indicates which parameter to associate the data
with. Parameters are numbered beginning with 0. `data' is a pointer to
a buffer containing data to be sent, and `length' indicates the number
of bytes in the buffer.

*Note*:

The next *Note `mysql_stmt_execute()': mysql-stmt-execute.  call
ignores the bind buffer for all parameters that have been used with
*Note `mysql_stmt_send_long_data()': mysql-stmt-send-long-data.  since
last *Note `mysql_stmt_execute()': mysql-stmt-execute. or *Note
`mysql_stmt_reset()': mysql-stmt-reset.

If you want to reset/forget the sent data, you can do it with *Note
`mysql_stmt_reset()': mysql-stmt-reset. See *Note mysql-stmt-reset::.

*Return Values*

Zero if the data is sent successfully to server. Non-zero if an error
occurred.

*Errors*

   * `CR_INVALID_BUFFER_USE'

     The parameter does not have a string or binary type.

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.

*Example*

The following example demonstrates how to send the data for a `TEXT'
column in chunks. It inserts the data value `'MySQL - The most popular
Open Source database'' into the `text_column' column. The `mysql'
variable is assumed to be a valid connection handle.

     #define INSERT_QUERY "INSERT INTO \
                           test_long_data(text_column) VALUES(?)"

     MYSQL_BIND bind[1];
     long       length;

     stmt = mysql_stmt_init(mysql);
     if (!stmt)
     {
       fprintf(stderr, " mysql_stmt_init(), out of memory\n");
       exit(0);
     }
     if (mysql_stmt_prepare(stmt, INSERT_QUERY, strlen(INSERT_QUERY)))
     {
       fprintf(stderr, "\n mysql_stmt_prepare(), INSERT failed");
       fprintf(stderr, "\n %s", mysql_stmt_error(stmt));
       exit(0);
     }
      memset(bind, 0, sizeof(bind));
      bind[0].buffer_type= MYSQL_TYPE_STRING;
      bind[0].length= &length;
      bind[0].is_null= 0;

     /* Bind the buffers */
     if (mysql_stmt_bind_param(stmt, bind))
     {
       fprintf(stderr, "\n param bind failed");
       fprintf(stderr, "\n %s", mysql_stmt_error(stmt));
       exit(0);
     }

      /* Supply data in chunks to server */
      if (mysql_stmt_send_long_data(stmt,0,"MySQL",5))
     {
       fprintf(stderr, "\n send_long_data failed");
       fprintf(stderr, "\n %s", mysql_stmt_error(stmt));
       exit(0);
     }

      /* Supply the next piece of data */
      if (mysql_stmt_send_long_data(stmt,0,
                " - The most popular Open Source database",40))
     {
       fprintf(stderr, "\n send_long_data failed");
       fprintf(stderr, "\n %s", mysql_stmt_error(stmt));
       exit(0);
     }

      /* Now, execute the query */
      if (mysql_stmt_execute(stmt))
     {
       fprintf(stderr, "\n mysql_stmt_execute failed");
       fprintf(stderr, "\n %s", mysql_stmt_error(stmt));
       exit(0);
     }


File: manual.info,  Node: mysql-stmt-sqlstate,  Next: mysql-stmt-store-result,  Prev: mysql-stmt-send-long-data,  Up: c-api-prepared-statement-functions

29.2.7.26 *Note `mysql_stmt_sqlstate()': mysql-stmt-sqlstate.
.............................................................

`const char *mysql_stmt_sqlstate(MYSQL_STMT *stmt)'

*Description*

For the statement specified by `stmt', *Note `mysql_stmt_sqlstate()':
mysql-stmt-sqlstate. returns a null-terminated string containing the
SQLSTATE error code for the most recently invoked prepared statement
API function that can succeed or fail. The error code consists of five
characters.  `"00000"' means `no error.' The values are specified by
ANSI SQL and ODBC. For a list of possible values, see *Note
error-handling::.

Note that not all MySQL errors are yet mapped to SQLSTATE codes.  The
value `"HY000"' (general error) is used for unmapped errors.

*Return Values*

A null-terminated character string containing the SQLSTATE error code.


File: manual.info,  Node: mysql-stmt-store-result,  Prev: mysql-stmt-sqlstate,  Up: c-api-prepared-statement-functions

29.2.7.27 *Note `mysql_stmt_store_result()': mysql-stmt-store-result.
.....................................................................

`int mysql_stmt_store_result(MYSQL_STMT *stmt)'

*Description*

Result sets are produced by executing prepared statements for SQL
statements such as `SELECT', `SHOW', `DESCRIBE', and `EXPLAIN'. By
default, result sets for successfully executed prepared statements are
not buffered on the client and *Note `mysql_stmt_fetch()':
mysql-stmt-fetch. fetches them one at a time from the server. To cause
the complete result set to be buffered on the client, call *Note
`mysql_stmt_store_result()': mysql-stmt-store-result. after binding
data buffers with *Note `mysql_stmt_bind_result()':
mysql-stmt-bind-result. and before calling *Note `mysql_stmt_fetch()':
mysql-stmt-fetch. to fetch rows. (For an example, see *Note
mysql-stmt-fetch::.)

*Note `mysql_stmt_store_result()': mysql-stmt-store-result. is optional
for result set processing, unless you will call *Note
`mysql_stmt_data_seek()': mysql-stmt-data-seek, *Note
`mysql_stmt_row_seek()': mysql-stmt-row-seek, or *Note
`mysql_stmt_row_tell()': mysql-stmt-row-tell. Those functions require a
seekable result set.

It is unnecessary to call *Note `mysql_stmt_store_result()':
mysql-stmt-store-result. after executing a SQL statement that does not
produce a result set, but if you do, it does not harm or cause any
notable performance problem. You can detect whether the statement
produced a result set by checking if *Note
`mysql_stmt_result_metadata()': mysql-stmt-result-metadata.  returns
`NULL'. For more information, refer to *Note
mysql-stmt-result-metadata::.

*Note*:

MySQL doesn't by default calculate `MYSQL_FIELD->max_length' for all
columns in *Note `mysql_stmt_store_result()': mysql-stmt-store-result.
because calculating this would slow down *Note
`mysql_stmt_store_result()': mysql-stmt-store-result.  considerably and
most applications doesn't need `max_length'. If you want `max_length'
to be updated, you can call *Note `mysql_stmt_attr_set(MYSQL_STMT,
STMT_ATTR_UPDATE_MAX_LENGTH, &flag)': mysql-stmt-attr-set. to enable
this. See *Note mysql-stmt-attr-set::.

*Return Values*

Zero if the results are buffered successfully. Non-zero if an error
occurred.

*Errors*

   * `CR_COMMANDS_OUT_OF_SYNC'

     Commands were executed in an improper order.

   * `CR_OUT_OF_MEMORY'

     Out of memory.

   * `CR_SERVER_GONE_ERROR'

     The MySQL server has gone away.

   * `CR_SERVER_LOST'

     The connection to the server was lost during the query.

   * `CR_UNKNOWN_ERROR'

     An unknown error occurred.


File: manual.info,  Node: c-api-prepared-statement-problems,  Next: c-api-multiple-queries,  Prev: c-api-prepared-statement-functions,  Up: c

29.2.8 C API Prepared Statement Problems
----------------------------------------

Here follows a list of the currently known problems with prepared
statements:

   * `TIME', `TIMESTAMP', and `DATETIME' do not support parts of seconds
     (for example, from `DATE_FORMAT()').

   * When converting an integer to string, `ZEROFILL' is honored with
     prepared statements in some cases where the MySQL server doesn't
     print the leading zeros. (For example, with
     `MIN(NUMBER-WITH-ZEROFILL)').

   * When converting a floating-point number to a string in the client,
     the rightmost digits of the converted value may differ slightly
     from those of the original value.

   * Before MySQL 5.1.17, prepared statements do not use the query
     cache. As of 5.1.17, prepared statements use the query cache under
     the conditions described in *Note query-cache-how::.

   * Prepared statements do not support multi-statements (that is,
     multiple statements within a single string separated by ``;''
     characters). This also means that prepared statements cannot
     invoke stored procedures that return result sets, because prepared
     statements do not support multiple result sets.


File: manual.info,  Node: c-api-multiple-queries,  Next: c-api-date-handling,  Prev: c-api-prepared-statement-problems,  Up: c

29.2.9 C API Handling of Multiple Statement Execution
-----------------------------------------------------

By default, *Note `mysql_query()': mysql-query. and *Note
`mysql_real_query()': mysql-real-query. interpret their statement
string argument as a single statement to be executed, and you process
the result according to whether the statement produces a result set (a
set of rows, as for `SELECT') or an affected-rows count (as for
`INSERT', `UPDATE', and so forth).

MySQL 5.1 also supports the execution of a string containing multiple
statements separated by semicolon (``;'') characters. This capability
is enabled by special options that are specified either when you
connect to the server with *Note `mysql_real_connect()':
mysql-real-connect. or after connecting by calling` *Note
`mysql_set_server_option()': mysql-set-server-option.

Executing a multiple-statement string can produce multiple result sets
or row-count indicators. Processing these results involves a different
approach than for the single-statement case: After handling the result
from the first statement, it is necessary to check whether more results
exist and process them in turn if so.  To support multiple-result
processing, the C API includes the *Note `mysql_more_results()':
mysql-more-results. and *Note `mysql_next_result()': mysql-next-result.
functions.  These functions are used at the end of a loop that iterates
as long as more results are available. _Failure to process the result
this way may result in a dropped connection to the server._

Multiple-result processing also is required if you execute `CALL'
statements for stored procedures. Results from a stored procedure have
these characteristics:

   * Statements within the procedure may produce result sets (for
     example, if it executes `SELECT' statements).  These result sets
     are returned in the order that they are produced as the procedure
     executes.

     In general, the caller cannot know how many result sets a
     procedure will return. Procedure execution may depend on loops or
     conditional statements that cause the execution path to differ
     from one call to the next. Therefore, you must be prepared to
     retrieve multiple results.

   * The final result from the procedure is a status result that
     includes no result set. The status indicates whether the procedure
     succeeded or an error occurred.

The multiple statement and result capabilities can be used only with
*Note `mysql_query()': mysql-query. or *Note `mysql_real_query()':
mysql-real-query. They cannot be used with the prepared statement
interface. Prepared statement handles are defined to work only with
strings that contain a single statement. See *Note
c-api-prepared-statements::.

To enable multiple-statement execution and result processing, the
following options may be used:

   * The *Note `mysql_real_connect()': mysql-real-connect.  function
     has a `flags' argument for which two option values are relevent:

        * `CLIENT_MULTI_RESULTS' enables the client program to process
          multiple results. This option _must_ be enabled if you execute
          `CALL' statements for stored procedures that produce result
          sets. Otherwise, such procedures result in an error `Error
          1312 (0A000): PROCEDURE PROC_NAME can't return a result set
          in the given context'.

        * `CLIENT_MULTI_STATEMENTS' enables *Note `mysql_query()':
          mysql-query. and *Note `mysql_real_query()':
          mysql-real-query. to execute statement strings containing
          multiple statements separated by semicolons. This option also
          enables `CLIENT_MULTI_RESULTS' implicitly, so a `flags'
          argument of `CLIENT_MULTI_STATEMENTS' to *Note
          `mysql_real_connect()': mysql-real-connect. is equivalent to
          an argument of `CLIENT_MULTI_STATEMENTS |
          CLIENT_MULTI_RESULTS'. That is, `CLIENT_MULTI_STATEMENTS' is
          sufficient to enable multiple-statement execution and all
          multiple-result processing.

   * After the connection to the server has been established, you can
     use the *Note `mysql_set_server_option()': mysql-set-server-option.
     function to enable or disable multiple-statement execution by
     passing it an argument of `MYSQL_OPTION_MULTI_STATEMENTS_ON' or
     `MYSQL_OPTION_MULTI_STATEMENTS_OFF'. Enabling multiple-statement
     execution with this function also enables processing of `simple'
     results for a multiple-statement string where each statement
     produces a single result, but is _not_ sufficient to allow
     processing of stored procedures that produce result sets.

The following procedure outlines a suggested strategy for handling
multiple statements:

  1. Pass `CLIENT_MULTI_STATEMENTS' to *Note `mysql_real_connect()':
     mysql-real-connect, to fully enable multiple-statement execution
     and multiple-result processing.

  2. After calling *Note `mysql_query()': mysql-query.  or *Note
     `mysql_real_query()': mysql-real-query. and verifying that it
     succeeds, enter a loop within which you process statement results.

  3. For each iteration of the loop, handle the current statement
     result, retrieving either a result set or an affected-rows count.
     If an error occurs, exit the loop.

  4. At the end of the loop, call *Note `mysql_next_result()':
     mysql-next-result. to check whether another result exists and
     initiate retrieval for it if so. If no more results are available,
     exit the loop.

One possible implementation of the preceding strategy is shown
following. The final part of the loop can be reduced to a simple test
of whether *Note `mysql_next_result()': mysql-next-result. returns
non-zero. The code as written distinguishes between no more results and
an error, which allows a message to be printed for the latter
occurrence.

     /* connect to server with the CLIENT_MULTI_STATEMENTS option */
     if (mysql_real_connect (mysql, host_name, user_name, password,
         db_name, port_num, socket_name, CLIENT_MULTI_STATEMENTS) == NULL)
     {
       printf("mysql_real_connect() failed\n");
       mysql_close(mysql);
       exit(1);
     }

     /* execute multiple statements */
     status = mysql_query(mysql,
                          "DROP TABLE IF EXISTS test_table;\
                           CREATE TABLE test_table(id INT);\
                           INSERT INTO test_table VALUES(10);\
                           UPDATE test_table SET id=20 WHERE id=10;\
                           SELECT * FROM test_table;\
                           DROP TABLE test_table");
     if (status)
     {
       printf("Could not execute statement(s)");
       mysql_close(mysql);
       exit(0);
     }

     /* process each statement result */
     do {
       /* did current statement return data? */
       result = mysql_store_result(mysql);
       if (result)
       {
         /* yes; process rows and free the result set */
         process_result_set(mysql, result);
         mysql_free_result(result);
       }
       else          /* no result set or error */
       {
         if (mysql_field_count(mysql) == 0)
         {
           printf("%lld rows affected\n",
                 mysql_affected_rows(mysql));
         }
         else  /* some error occurred */
         {
           printf("Could not retrieve result set\n");
           break;
         }
       }
       /* more results? -1 = no, >0 = error, 0 = yes (keep looping) */
       if ((status = mysql_next_result(mysql)) > 0)
         printf("Could not execute statement\n");
     } while (status == 0);

     mysql_close(mysql);


File: manual.info,  Node: c-api-date-handling,  Next: c-thread-functions,  Prev: c-api-multiple-queries,  Up: c

29.2.10 C API Handling of Date and Time Values
----------------------------------------------

The binary (prepared statement) protocol allows you to send and receive
date and time values (`DATE', `TIME', `DATETIME', and `TIMESTAMP'),
using the `MYSQL_TIME' structure. The members of this structure are
described in *Note c-api-prepared-statement-datatypes::.

To send temporal data values, create a prepared statement using *Note
`mysql_stmt_prepare()': mysql-stmt-prepare. Then, before calling *Note
`mysql_stmt_execute()': mysql-stmt-execute. to execute the statement,
use the following procedure to set up each temporal parameter:

  1. In the `MYSQL_BIND' structure associated with the data value, set
     the `buffer_type' member to the type that indicates what kind of
     temporal value you're sending. For `DATE', `TIME', `DATETIME', or
     `TIMESTAMP' values, set `buffer_type' to `MYSQL_TYPE_DATE',
     `MYSQL_TYPE_TIME', `MYSQL_TYPE_DATETIME', or
     `MYSQL_TYPE_TIMESTAMP', respectively.

  2. Set the `buffer' member of the `MYSQL_BIND' structure to the
     address of the `MYSQL_TIME' structure in which you pass the
     temporal value.

  3. Fill in the members of the `MYSQL_TIME' structure that are
     appropriate for the type of temporal value to be passed.

Use *Note `mysql_stmt_bind_param()': mysql-stmt-bind-param. to bind the
parameter data to the statement. Then you can call *Note
`mysql_stmt_execute()': mysql-stmt-execute.

To retrieve temporal values, the procedure is similar, except that you
set the `buffer_type' member to the type of value you expect to
receive, and the `buffer' member to the address of a `MYSQL_TIME'
structure into which the returned value should be placed. Use *Note
`mysql_stmt_bind_result()': mysql-stmt-bind-result. to bind the buffers
to the statement after calling *Note `mysql_stmt_execute()':
mysql-stmt-execute. and before fetching the results.

Here is a simple example that inserts `DATE', `TIME', and `TIMESTAMP'
data.  The `mysql' variable is assumed to be a valid connection handle.


       MYSQL_TIME  ts;
       MYSQL_BIND  bind[3];
       MYSQL_STMT  *stmt;

       strmov(query, "INSERT INTO test_table(date_field, time_field, \
                                    timestamp_field) VALUES(?,?,?");

       stmt = mysql_stmt_init(mysql);
       if (!stmt)
       {
         fprintf(stderr, " mysql_stmt_init(), out of memory\n");
         exit(0);
       }
       if (mysql_stmt_prepare(mysql, query, strlen(query)))
       {
         fprintf(stderr, "\n mysql_stmt_prepare(), INSERT failed");
         fprintf(stderr, "\n %s", mysql_stmt_error(stmt));
         exit(0);
       }

       /* set up input buffers for all 3 parameters */
       bind[0].buffer_type= MYSQL_TYPE_DATE;
       bind[0].buffer= (char *)&ts;
       bind[0].is_null= 0;
       bind[0].length= 0;
       ...
       bind[1]= bind[2]= bind[0];
       ...

       mysql_stmt_bind_param(stmt, bind);

       /* supply the data to be sent in the ts structure */
       ts.year= 2002;
       ts.month= 02;
       ts.day= 03;

       ts.hour= 10;
       ts.minute= 45;
       ts.second= 20;

       mysql_stmt_execute(stmt);
       ..


File: manual.info,  Node: c-thread-functions,  Next: c-embedded-server-func,  Prev: c-api-date-handling,  Up: c

29.2.11 C API Threaded Function Descriptions
--------------------------------------------

* Menu:

* my-init::                      *Note `my_init()': my-init.
* mysql-thread-end::             *Note `mysql_thread_end()': mysql-thread-end.
* mysql-thread-init::            *Note `mysql_thread_init()': mysql-thread-init.
* mysql-thread-safe::            *Note `mysql_thread_safe()': mysql-thread-safe.

You need to use the following functions when you want to create a
threaded client. See *Note threaded-clients::.


File: manual.info,  Node: my-init,  Next: mysql-thread-end,  Prev: c-thread-functions,  Up: c-thread-functions

29.2.11.1 *Note `my_init()': my-init.
.....................................

`void my_init(void)'

*Description*

*Note `my_init()': my-init. initializes some global variables that
MySQL needs. If you are using a thread-safe client library, it also
calls *Note `mysql_thread_init()': mysql-thread-init. for this thread.

It is necessary for *Note `my_init()': my-init.  to be called early in
the initialization phase of a program's use of the MySQL library.
However, *Note `my_init()': my-init. is automatically called by *Note
`mysql_init()': mysql-init, *Note `mysql_library_init()':
mysql-library-init, *Note `mysql_server_init()': mysql-server-init, and
*Note `mysql_connect()': mysql-connect. If you ensure that your program
invokes one of those functions before any other MySQL calls, there is
no need to invoke *Note `my_init()': my-init. explicitly.

To access *Note `my_init()': my-init, your program must include the
`my_sys.h' header file:

     #include <my_sys.h>

*Return Values*

None.


File: manual.info,  Node: mysql-thread-end,  Next: mysql-thread-init,  Prev: my-init,  Up: c-thread-functions

29.2.11.2 *Note `mysql_thread_end()': mysql-thread-end.
.......................................................

`void mysql_thread_end(void)'

*Description*

This function needs to be called before calling `pthread_exit()' to
free memory allocated by *Note `mysql_thread_init()': mysql-thread-init.

*Note `mysql_thread_end()': mysql-thread-end. _is not invoked
automatically by the client library_. It must be called explicitly to
avoid a memory leak.

*Return Values*

None.


File: manual.info,  Node: mysql-thread-init,  Next: mysql-thread-safe,  Prev: mysql-thread-end,  Up: c-thread-functions

29.2.11.3 *Note `mysql_thread_init()': mysql-thread-init.
.........................................................

`my_bool mysql_thread_init(void)'

*Description*

This function must be called early within each created thread to
initialize thread-specific variables. However, you may not necessarily
need to invoke it explicitly: *Note `mysql_thread_init()':
mysql-thread-init. is automatically called by *Note `my_init()':
my-init, which itself is automatically called by *Note `mysql_init()':
mysql-init, *Note `mysql_library_init()': mysql-library-init, *Note
`mysql_server_init()': mysql-server-init, and *Note `mysql_connect()':
mysql-connect. If you invoke any of those functions, *Note
`mysql_thread_init()': mysql-thread-init. will be called for you.

*Return Values*

Zero if successful. Non-zero if an error occurred.


File: manual.info,  Node: mysql-thread-safe,  Prev: mysql-thread-init,  Up: c-thread-functions

29.2.11.4 *Note `mysql_thread_safe()': mysql-thread-safe.
.........................................................

`unsigned int mysql_thread_safe(void)'

*Description*

This function indicates whether the client library is compiled as
thread-safe.

*Return Values*

1 if the client library is thread-safe, 0 otherwise.


File: manual.info,  Node: c-embedded-server-func,  Next: auto-reconnect,  Prev: c-thread-functions,  Up: c

29.2.12 C API Embedded Server Function Descriptions
---------------------------------------------------

* Menu:

* mysql-server-init::            *Note `mysql_server_init()': mysql-server-init.
* mysql-server-end::             *Note `mysql_server_end()': mysql-server-end.

MySQL applications can be written to use an embedded server. See *Note
libmysqld::. To write such an application, you must link it against the
`libmysqld' library by using the `-lmysqld' flag rather than linking it
against the `libmysqlclient' client library by using the
`-lmysqlclient' flag. However, the calls to initialize and finalize the
library are the same whether you write a client application or one that
uses the embedded server: Call *Note `mysql_library_init()':
mysql-library-init. to initialize the library and *Note
`mysql_library_end()': mysql-library-end. when you are done with it.
See *Note c-api-function-overview::.


File: manual.info,  Node: mysql-server-init,  Next: mysql-server-end,  Prev: c-embedded-server-func,  Up: c-embedded-server-func

29.2.12.1 *Note `mysql_server_init()': mysql-server-init.
.........................................................

`int mysql_server_init(int argc, char **argv, char **groups)'

*Description*

This function initializes the MySQL library, which must be done before
you call any other MySQL function. However, *Note
`mysql_server_init()': mysql-server-init. is deprecated and you should
call *Note `mysql_library_init()': mysql-library-init. instead.  See
*Note mysql-library-init::.

*Return Values*

Zero if successful. Non-zero if an error occurred.


File: manual.info,  Node: mysql-server-end,  Prev: mysql-server-init,  Up: c-embedded-server-func

29.2.12.2 *Note `mysql_server_end()': mysql-server-end.
.......................................................

`void mysql_server_end(void)'

*Description*

This function finalizes the MySQL library, which should be done when
you are done using the library. However, *Note `mysql_server_end()':
mysql-server-end. is deprecated and *Note `mysql_library_end()':
mysql-library-end. should be used instead. See *Note
mysql-library-end::.

*Return Values*

None.


File: manual.info,  Node: auto-reconnect,  Next: c-api-problems,  Prev: c-embedded-server-func,  Up: c

29.2.13 Controlling Automatic Reconnect Behavior
------------------------------------------------

The MySQL client library can perform an automatic reconnect to the
server if it finds that the connection is down when you attempt to send
a statement to the server to be executed. In this case, the library
tries once to reconnect to the server and send the statement again.

If it is important for your application to know that the connection has
been dropped (so that is can exit or take action to adjust for the loss
of state information), be sure to disable auto-reconnect. This can be
done explicitly by calling *Note `mysql_options()': mysql-options. with
the `MYSQL_OPT_RECONNECT' option:

     my_bool reconnect = 0;
     mysql_options(&mysql, MYSQL_OPT_RECONNECT, &reconnect);

In MySQL 5.1, auto-reconnect is disabled by default.

Some client programs might provide the capability of controlling
automatic reconnection. For example, `mysql' reconnects by default, but
the `--skip-reconnect' option can be used to suppress this behavior.

Automatic reconnection can be convenient because you need not implement
your own reconnect code, but if a reconnection does occur, several
aspects of the connection state are reset and your application will not
know about it. The connection-related state is affected as follows:

   * Any active transactions are rolled back and autocommit mode is
     reset.

   * All table locks are released.

   * All `TEMPORARY' tables are closed (and dropped).

   * Session variables are reinitialized to the values of the
     corresponding variables. This also affects variables that are set
     implicitly by statements such as `SET NAMES'.

   * User variable settings are lost.

   * Prepared statements are released.

   * `HANDLER' variables are closed.

   * The value of `LAST_INSERT_ID()' is reset to 0.

   * Locks acquired with `GET_LOCK()' are released.

   * *Note `mysql_ping()': mysql-ping. does not attempt a reconnection
     if the connection is down. It returns an error instead.


File: manual.info,  Node: c-api-problems,  Next: building-clients,  Prev: auto-reconnect,  Up: c

29.2.14 Common Questions and Problems When Using the C API
----------------------------------------------------------

* Menu:

* null-mysql-store-result::      Why *Note `mysql_store_result()': mysql-store-result. Sometimes Returns `NULL' After *Note `mysql_query()': mysql-query. Returns Success
* query-results::                What Results You Can Get from a Query
* getting-unique-id::            How to Get the Unique ID for the Last Inserted Row
* c-api-linking-problems::       Problems Linking with the C API

MySQL Enterprise

Subscribers to MySQL Enterprise will find articles about the C API in
the MySQL Knowledge Base. Access to the Knowledge Base collection of
articles is one of the advantages of subscribing to MySQL Enterprise.
For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: null-mysql-store-result,  Next: query-results,  Prev: c-api-problems,  Up: c-api-problems

29.2.14.1 Why *Note `mysql_store_result()': mysql-store-result. Sometimes Returns `NULL' After *Note `mysql_query()': mysql-query. Returns Success
..................................................................................................................................................

It is possible for *Note `mysql_store_result()': mysql-store-result. to
return `NULL' following a successful call to *Note `mysql_query()':
mysql-query. When this happens, it means one of the following
conditions occurred:

   * There was a `malloc()' failure (for example, if the result set was
     too large).

   * The data couldn't be read (an error occurred on the connection).

   * The query returned no data (for example, it was an `INSERT',
     `UPDATE', or `DELETE').

You can always check whether the statement should have produced a
non-empty result by calling *Note `mysql_field_count()':
mysql-field-count. If *Note `mysql_field_count()': mysql-field-count.
returns zero, the result is empty and the last query was a statement
that does not return values (for example, an `INSERT' or a `DELETE'). If
*Note `mysql_field_count()': mysql-field-count. returns a non-zero
value, the statement should have produced a non-empty result. See the
description of the *Note `mysql_field_count()': mysql-field-count.
function for an example.

You can test for an error by calling *Note `mysql_error()':
mysql-error. or *Note `mysql_errno()': mysql-errno.


File: manual.info,  Node: query-results,  Next: getting-unique-id,  Prev: null-mysql-store-result,  Up: c-api-problems

29.2.14.2 What Results You Can Get from a Query
...............................................

In addition to the result set returned by a query, you can also get the
following information:

   * *Note `mysql_affected_rows()': mysql-affected-rows.  returns the
     number of rows affected by the last query when doing an `INSERT',
     `UPDATE', or `DELETE'.

     For a fast re-create, use `TRUNCATE TABLE'.

   * *Note `mysql_num_rows()': mysql-num-rows. returns the number of
     rows in a result set. With *Note `mysql_store_result()':
     mysql-store-result, *Note `mysql_num_rows()': mysql-num-rows. may
     be called as soon as *Note `mysql_store_result()':
     mysql-store-result.  returns. With *Note `mysql_use_result()':
     mysql-use-result, *Note `mysql_num_rows()': mysql-num-rows. may be
     called only after you have fetched all the rows with *Note
     `mysql_fetch_row()': mysql-fetch-row.

   * *Note `mysql_insert_id()': mysql-insert-id. returns the ID
     generated by the last query that inserted a row into a table with
     an `AUTO_INCREMENT' index. See *Note mysql-insert-id::.

   * Some queries (`LOAD DATA INFILE ...', `INSERT INTO ... SELECT ...',
     `UPDATE') return additional information.  The result is returned by
     *Note `mysql_info()': mysql-info. See the description for *Note
     `mysql_info()': mysql-info. for the format of the string that it
     returns.  *Note `mysql_info()': mysql-info. returns a `NULL'
     pointer if there is no additional information.


File: manual.info,  Node: getting-unique-id,  Next: c-api-linking-problems,  Prev: query-results,  Up: c-api-problems

29.2.14.3 How to Get the Unique ID for the Last Inserted Row
............................................................

If you insert a record into a table that contains an `AUTO_INCREMENT'
column, you can obtain the value stored into that column by calling the
*Note `mysql_insert_id()': mysql-insert-id. function.

You can check from your C applications whether a value was stored in an
`AUTO_INCREMENT' column by executing the following code (which assumes
that you've checked that the statement succeeded). It determines
whether the query was an `INSERT' with an `AUTO_INCREMENT' index:

     if ((result = mysql_store_result(&mysql)) == 0 &&
         mysql_field_count(&mysql) == 0 &&
         mysql_insert_id(&mysql) != 0)
     {
         used_id = mysql_insert_id(&mysql);
     }

When a new `AUTO_INCREMENT' value has been generated, you can also
obtain it by executing a `SELECT LAST_INSERT_ID()' statement with *Note
`mysql_query()': mysql-query. and retrieving the value from the result
set returned by the statement.

When inserting multiple values, the last automatically incremented
value is returned.

For `LAST_INSERT_ID()', the most recently generated ID is maintained in
the server on a per-connection basis. It is not changed by another
client. It is not even changed if you update another `AUTO_INCREMENT'
column with a non-magic value (that is, a value that is not `NULL' and
not `0'). Using `LAST_INSERT_ID()' and `AUTO_INCREMENT' columns
simultaneously from multiple clients is perfectly valid. Each client
will receive the last inserted ID for the last statement _that_ client
executed.

If you want to use the ID that was generated for one table and insert
it into a second table, you can use SQL statements like this:

     INSERT INTO foo (auto,text)
         VALUES(NULL,'text');         # generate ID by inserting NULL
     INSERT INTO foo2 (id,text)
         VALUES(LAST_INSERT_ID(),'text');  # use ID in second table

Note that *Note `mysql_insert_id()': mysql-insert-id.  returns the
value stored into an `AUTO_INCREMENT' column, whether that value is
automatically generated by storing `NULL' or `0' or was specified as an
explicit value.  `LAST_INSERT_ID()' returns only automatically
generated `AUTO_INCREMENT' values. If you store an explicit value other
than `NULL' or `0', it does not affect the value returned by
`LAST_INSERT_ID()'.

For more information on obtaining the last ID in an `AUTO_INCREMENT'
column:

   * For information on `LAST_INSERT_ID()', which can be used within an
     SQL statement, see *Note information-functions::.

   * For information on *Note `mysql_insert_id()': mysql-insert-id, the
     function you use from within the C API, see *Note
     mysql-insert-id::.

   * For information on obtaining the auto-incremented value when using
     Connector/J, see *Note connector-j-usagenotes::.

   * For information on obtaining the auto-incremented value when using
     Connector/ODBC, see *Note
     myodbc-usagenotes-functionality-last-insert-id::.


File: manual.info,  Node: c-api-linking-problems,  Prev: getting-unique-id,  Up: c-api-problems

29.2.14.4 Problems Linking with the C API
.........................................

When linking with the C API, the following errors may occur on some
systems:

     gcc -g -o client test.o -L/usr/local/lib/mysql \
                             -lmysqlclient -lsocket -lnsl

     Undefined        first referenced
      symbol          in file
     floor            /usr/local/lib/mysql/libmysqlclient.a(password.o)
     ld: fatal: Symbol referencing errors. No output written to client

If this happens on your system, you must include the math library by
adding `-lm' to the end of the compile/link line.


File: manual.info,  Node: building-clients,  Next: threaded-clients,  Prev: c-api-problems,  Up: c

29.2.15 Building Client Programs
--------------------------------

If you compile MySQL clients that you've written yourself or that you
obtain from a third-party, they must be linked using the `-lmysqlclient
-lz' options in the link command.  You may also need to specify a `-L'
option to tell the linker where to find the library. For example, if
the library is installed in `/usr/local/mysql/lib', use
`-L/usr/local/mysql/lib -lmysqlclient -lz' in the link command.

For clients that use MySQL header files, you may need to specify an
`-I' option when you compile them (for example,
`-I/usr/local/mysql/include'), so that the compiler can find the header
files.

To make it simpler to compile MySQL programs on Unix, we have provided
the `mysql_config' script for you. See *Note mysql-config::.

You can use it to compile a MySQL client as follows:

     CFG=/usr/local/mysql/bin/mysql_config
     sh -c "gcc -o progname `$CFG --cflags` progname.c `$CFG --libs`"

The `sh -c' is needed to get the shell not to treat the output from
`mysql_config' as one word.

MySQL Enterprise

Subscribers to MySQL Enterprise will find an example client program in
the Knowledge Base article, Sample C program using the embedded MySQL
server library (https://kb.mysql.com/view.php?id=5264). Access to the
MySQL Knowledge Base collection of articles is one of the advantages of
subscribing to MySQL Enterprise. For more information see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: threaded-clients,  Prev: building-clients,  Up: c

29.2.16 How to Make a Threaded Client
-------------------------------------

The client library is almost thread-safe. The biggest problem is that
the subroutines in `net.c' that read from sockets are not interrupt
safe. This was done with the thought that you might want to have your
own alarm that can break a long read to a server. If you install
interrupt handlers for the `SIGPIPE' interrupt, the socket handling
should be thread-safe.

To avoid aborting the program when a connection terminates, MySQL
blocks `SIGPIPE' on the first call to *Note `mysql_library_init()':
mysql-library-init, *Note `mysql_init()': mysql-init, or *Note
`mysql_connect()': mysql-connect. If you want to use your own `SIGPIPE'
handler, you should first call *Note `mysql_library_init()':
mysql-library-init. and then install your handler.

Before MySQL 4.0, binary client libraries that we provided other than
those for Windows were not normally compiled with the thread-safe
option. Current binary distributions should have both a normal and a
thread-safe client library.

To create a threaded client where you can interrupt the client from
other threads and set timeouts when talking with the MySQL server, you
should use the `net_serv.o' code that the server uses and the `-lmysys',
`-lmystrings', and `-ldbug' libraries.

If you don't need interrupts or timeouts, you can just compile a
thread-safe client library `(mysqlclient_r)' and use it. In this case,
you don't have to worry about the `net_serv.o' object file or the other
MySQL libraries.

When using a threaded client and you want to use timeouts and
interrupts, you can make great use of the routines in the `thr_alarm.c'
file. If you are using routines from the `mysys' library, the only
thing you must remember is to call *Note `my_init()': my-init.  first!
See *Note c-thread-functions::.

In all cases, be sure to initialize the client library by calling *Note
`mysql_library_init()': mysql-library-init. before calling any other
MySQL functions. When you are done with the library, call *Note
`mysql_library_end()': mysql-library-end.

*Note `mysql_real_connect()': mysql-real-connect. is not thread-safe by
default. The following notes describe how to compile a thread-safe
client library and use it in a thread-safe manner. (The notes below for
*Note `mysql_real_connect()': mysql-real-connect. also apply to the
older *Note `mysql_connect()': mysql-connect.  routine as well, although
*Note `mysql_connect()': mysql-connect. is deprecated and should no
longer be used.)

To make *Note `mysql_real_connect()': mysql-real-connect.  thread-safe,
you must configure your MySQL distribution with this command:

     shell> ./configure --enable-thread-safe-client

Then recompile the distribution to create a thread-safe client library,
`libmysqlclient_r'. (Assuming that your operating system has a
thread-safe `gethostbyname_r()' function.) This library is thread-safe
per connection. You can let two threads share the same connection with
the following caveats:

   * Two threads can't send a query to the MySQL server at the same
     time on the same connection. In particular, you have to ensure
     that between calls to *Note `mysql_query()': mysql-query. and
     *Note `mysql_store_result()': mysql-store-result. no other thread
     is using the same connection.

   * Many threads can access different result sets that are retrieved
     with *Note `mysql_store_result()': mysql-store-result.

   * If you use *Note `mysql_use_result()': mysql-use-result, you must
     ensure that no other thread is using the same connection until the
     result set is closed. However, it really is best for threaded
     clients that share the same connection to use *Note
     `mysql_store_result()': mysql-store-result.

   * If you want to use multiple threads on the same connection, you
     must have a mutex lock around your pair of *Note `mysql_query()':
     mysql-query. and *Note `mysql_store_result()': mysql-store-result.
     calls.  Once *Note `mysql_store_result()': mysql-store-result. is
     ready, the lock can be released and other threads may query the
     same connection.

   * If you use POSIX threads, you can use `pthread_mutex_lock()' and
     `pthread_mutex_unlock()' to establish and release a mutex lock.

You need to know the following if you have a thread that is calling
MySQL functions which did not create the connection to the MySQL
database:

When you call *Note `mysql_init()': mysql-init, MySQL creates a
thread-specific variable for the thread that is used by the debug
library (among other things). If you call a MySQL function before the
thread has called *Note `mysql_init()': mysql-init, the thread does not
have the necessary thread-specific variables in place and you are
likely to end up with a core dump sooner or later. To get things to
work smoothly you must do the following:

  1. Call *Note `mysql_library_init()': mysql-library-init.  before any
     other MySQL functions. It is not thread-safe, so call it before
     threads are created, or protect the call with a mutex.

  2. Arrange for *Note `mysql_thread_init()': mysql-thread-init. to be
     called early in the thread handler before calling any MySQL
     function. If you call *Note `mysql_init()': mysql-init, they will
     call *Note `mysql_thread_init()': mysql-thread-init. for you.

  3. In the thread, call *Note `mysql_thread_end()': mysql-thread-end.
     before calling `pthread_exit()'. This frees the memory used by
     MySQL thread-specific variables.

The preceding notes regarding *Note `mysql_init()': mysql-init. also
apply to *Note `mysql_connect()': mysql-connect, which calls *Note
`mysql_init()': mysql-init.

If `undefined symbol' errors occur when linking your client with
`libmysqlclient_r', in most cases this is because you haven't included
the thread libraries on the link/compile command.


File: manual.info,  Node: php,  Next: perl,  Prev: c,  Up: apis

29.3 MySQL PHP API
==================

* Menu:

* php-problems::                 Common Problems with MySQL and PHP
* php-mysql-mysqli::             Enabling Both `mysql' and `mysqli' in PHP

PHP is a server-side, HTML-embedded scripting language that may be used
to create dynamic Web pages. It is available for most operating systems
and Web servers, and can access most common databases, including MySQL.
PHP may be run as a separate program or compiled as a module for use
with the Apache Web server.

PHP actually provides two different MySQL API extensions:

   * `mysql': Available for PHP versions 4 and 5, this extension is
     intended for use with MySQL versions prior to MySQL 4.1. This
     extension does not support the improved authentication protocol
     used in MySQL 4.1, nor does it support prepared statements or
     multiple statements. If you wish to use this extension with MySQL
     4.1, you will likely want to configure the MySQL server to use the
     `--old-passwords' option (see *Note old-client::). This extension
     is documented on the PHP Web site at `http://php.net/mysql'.

   * `mysqli' - Stands for `MySQL, Improved'; this extension is
     available only in PHP 5. It is intended for use with MySQL 4.1.1
     and later. This extension fully supports the authentication
     protocol used in MySQL 5.0, as well as the Prepared Statements and
     Multiple Statements APIs. In addition, this extension provides an
     advanced, object-oriented programming interface. You can read the
     documentation for the `mysqli' extension at
     `http://php.net/mysqli'. Helpful article can be found at
     `http://devzone.zend.com/node/view/id/686' and
     `http://devzone.zend.com/node/view/id/687'.

If you're experiencing problems with enabling both the `mysql' and the
`mysqli' extension when building PHP on Linux yourself, see *Note
php-mysql-mysqli::.

The PHP distribution and documentation are available from the PHP Web
site (http://www.php.net/).

MySQL Enterprise

MySQL Enterprise subscribers will find more information about MySQL and
PHP in the Knowledge Base articles found at PHP
(https://kb.mysql.com/search.php?cat=search&category=23). Access to the
MySQL Knowledge Base collection of articles is one of the advantages of
subscribing to MySQL Enterprise. For more information see
`http://www.mysql.com/products/enterprise/knowledgebase.html'.


File: manual.info,  Node: php-problems,  Next: php-mysql-mysqli,  Prev: php,  Up: php

29.3.1 Common Problems with MySQL and PHP
-----------------------------------------

   * `Error: Maximum Execution Time Exceeded': This is a PHP limit; go
     into the `php.ini' file and set the maximum execution time up from
     30 seconds to something higher, as needed. It is also not a bad
     idea to double the RAM allowed per script to 16MB instead of 8MB.

   * `Fatal error: Call to unsupported or undefined function
     mysql_connect() in ...': This means that your PHP version isn't
     compiled with MySQL support. You can either compile a dynamic
     MySQL module and load it into PHP or recompile PHP with built-in
     MySQL support. This process is described in detail in the PHP
     manual.

   * `Error: Undefined reference to 'uncompress'': This means that the
     client library is compiled with support for a compressed
     client/server protocol. The fix is to add `-lz' last when linking
     with `-lmysqlclient'.

   * `Error: Client does not support authentication protocol': This is
     most often encountered when trying to use the older `mysql'
     extension with MySQL 4.1.1 and later. Possible solutions are:
     downgrade to MySQL 4.0; switch to PHP 5 and the newer `mysqli'
     extension; or configure the MySQL server with `--old-passwords'.
     (See *Note old-client::, for more information.)

Those with PHP4 legacy code can make use of a compatibility layer for
the old and new MySQL libraries, such as this one:
`http://www.coggeshall.org/oss/mysql2i'.


File: manual.info,  Node: php-mysql-mysqli,  Prev: php-problems,  Up: php

29.3.2 Enabling Both `mysql' and `mysqli' in PHP
------------------------------------------------

If you're experiencing problems with enabling both the `mysql' and the
`mysqli' extension when building PHP on Linux yourself, you should try
the following procedure.

  1. Configure PHP like this:

          ./configure --with-mysqli=/usr/bin/mysql_config --with-mysql=/usr

  2. Edit the `Makefile' and search for a line that starts with
     `EXTRA_LIBS'. It might look like this (all on one line):

          EXTRA_LIBS = -lcrypt -lcrypt -lmysqlclient -lz -lresolv -lm -ldl -lnsl
          -lxml2 -lz -lm -lxml2 -lz -lm -lmysqlclient -lz -lcrypt -lnsl -lm
          -lxml2 -lz -lm -lcrypt -lxml2 -lz -lm -lcrypt

     Remove all duplicates, so that the line looks like this (all on
     one line):

          EXTRA_LIBS = -lcrypt -lcrypt -lmysqlclient -lz -lresolv -lm -ldl -lnsl
          -lxml2

  3. Build and install PHP:

          make
          make install

MySQL Enterprise

MySQL Enterprise subscribers will find more information about the
mysqli extension in the Knowledge Base articles found at mysqli
(https://kb.mysql.com/search.php?cat=search&cat=search&keywords=mysqli&go=Go).
Access to the MySQL Knowledge Base collection of articles is one of the
advantages of subscribing to MySQL Enterprise. For more information see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: perl,  Next: cplusplus,  Prev: php,  Up: apis

29.4 MySQL Perl API
===================

The Perl `DBI' module provides a generic interface for database access.
You can write a DBI script that works with many different database
engines without change. To use DBI, you must install the `DBI' module,
as well as a DataBase Driver (DBD) module for each type of server you
want to access. For MySQL, this driver is the `DBD::mysql' module.

Perl DBI is the recommended Perl interface. It replaces an older
interface called `mysqlperl', which should be considered obsolete.

Installation instructions for Perl DBI support are given in *Note
perl-support::.

DBI information is available at the command line, online, or in printed
form:

   * Once you have the `DBI' and `DBD::mysql' modules installed, you
     can get information about them at the command line with the
     `perldoc' command:

          shell> perldoc DBI
          shell> perldoc DBI::FAQ
          shell> perldoc DBD::mysql

     You can also use `pod2man', `pod2html', and so forth to translate
     this information into other formats.

   * For online information about Perl DBI, visit the DBI Web site,
     `http://dbi.perl.org/'. That site hosts a general DBI mailing
     list. MySQL AB hosts a list specifically about `DBD::mysql'; see
     *Note mailing-lists::.

   * For printed information, the official DBI book is `Programming the
     Perl DBI' (Alligator Descartes and Tim Bunce, O'Reilly &
     Associates, 2000).  Information about the book is available at the
     DBI Web site, `http://dbi.perl.org/'.

     For information that focuses specifically on using DBI with MySQL,
     see `MySQL and Perl for the Web' (Paul DuBois, New Riders, 2001).
     This book's Web site is `http://www.kitebird.com/mysql-perl/'.


File: manual.info,  Node: cplusplus,  Next: python,  Prev: perl,  Up: apis

29.5 MySQL C++ API
==================

`MySQL++' is a MySQL API for C++. Warren Young has taken over this
project. More information can be found at
`http://tangentsoft.net/mysql++/doc'.

MySQL Enterprise

MySQL Enterprise subscribers will find more information about using C++
with the MySQL API in the MySQL Knowledge Base. articles found at C++
(https://kb.mysql.com/search.php?cat=search&pagerRow=0&category=18).
Access to the MySQL Knowledge Base collection of articles is one of the
advantages of subscribing to MySQL Enterprise. For more information see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: python,  Next: tcl,  Prev: cplusplus,  Up: apis

29.6 MySQL Python API
=====================

`MySQLdb' provides MySQL support for Python, compliant with the Python
DB API version 2.0. It can be found at
`http://sourceforge.net/projects/mysql-python/'.

MySQL Enterprise

MySQL Enterprise subscribers will find more information about using
Python with the MySQL API in the MySQL Knowledge Base articles found at
Python (https://kb.mysql.com/search.php?cat=search&category=24). Access
to the MySQL Knowledge Base collection of articles is one of the
advantages of subscribing to MySQL Enterprise. For more information see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: tcl,  Next: eiffel,  Prev: python,  Up: apis

29.7 MySQL Tcl API
==================

`MySQLtcl' is a simple API for accessing a MySQL database server from
the Tcl programming language. It can be found at
`http://www.xdobry.de/mysqltcl/'.


File: manual.info,  Node: eiffel,  Prev: tcl,  Up: apis

29.8 MySQL Eiffel Wrapper
=========================

Eiffel MySQL is an interface to the MySQL database server using the
Eiffel programming language, written by Michael Ravits. It can be found
at `http://efsa.sourceforge.net/archive/ravits/mysql.htm'.


File: manual.info,  Node: connectors,  Next: extending-mysql,  Prev: apis,  Up: Top

30 Connectors
*************

* Menu:

* myodbc-connector::             MySQL Connector/ODBC
* connector-net::                MySQL Connector/NET
* connector-vstudio::            MySQL Visual Studio Plugin
* connector-j::                  MySQL Connector/J
* connector-mxj::                MySQL Connector/MXJ
* connector-php::                Connector/PHP

This chapter describes MySQL Connectors, drivers that provide
connectivity to the MySQL server for client programs. There are
currently five MySQL Connectors:

   * Connector/ODBC provides driver support for connecting to a MySQL
     server using the Open Database Connectivity (ODBC) API. Support is
     available for ODBC connectivity from Windows, Unix and Mac OS X
     platforms.

   * Connector/NET enables developers to create .NET applications that
     use data stored in a MySQL database. Connector/NET implements a
     fully-functional ADO.NET interface and provides support for use
     with ADO.NET aware tools. Applications that want to use
     Connector/NET can be written in any of the supported .NET
     languages.

   * The MySQL Visual Studio Plugin works with Connector/NET and Visual
     Studio 2005. The plugin is a MySQL DDEX Provider, which means that
     you can use the schema and data manipulation tools within Visual
     Studio to create and edit objects within a MySQL database.

   * Connector/J provides driver support for connecting to MySQL from a
     Java application using the standard Java Database Connectivity
     (JDBC) API.

   * Connector/MXJ is a tool that enables easy deployment and
     management of MySQL server and database through your Java
     application.

   * Connector/PHP is a Windows-only connector for PHP that provides
     the `mysql' and `mysqli' extensions for use with MySQL 5.0.18 and
     later.

For information on connecting to a MySQL server using other languages
and interfaces than those detailed above, including Perl, Python and
PHP for other platforms and environments, please refer to the *Note
apis:: chapter.


File: manual.info,  Node: myodbc-connector,  Next: connector-net,  Prev: connectors,  Up: connectors

30.1 MySQL Connector/ODBC
=========================

* Menu:

* myodbc-versions::              Connector/ODBC Versions
* myodbc-introduction::          Connector/ODBC Introduction
* myodbc-installation::          Connector/ODBC Installation
* myodbc-configuration::         Connector/ODBC Configuration
* myodbc-examples::              Connector/ODBC Examples
* myodbc-reference::             Connector/ODBC Reference
* myodbc-usagenotes::            Connector/ODBC Notes and Tips
* myodbc-support::               Connector/ODBC Support

The MySQL Connector/ODBC is the name for the family of MySQL ODBC
drivers (previously called MyODBC drivers) that provide access to a
MySQL database using the industry standard Open Database Connectivity
(ODBC) API. This reference covers Connector/ODBC 3.51 and
Connector/ODBC 5.1. Both releases provide an ODBC compliant interface
to MySQL Server.

MySQL Connector/ODBC provides both driver-manager based and native
interfaces to the MySQL database, which full support for MySQL
functionality, including stored procedures, transactions and, with
Connector/ODBC 5.1, full Unicode compliance.

For more information on the ODBC API standard and how to use it, refer
to `http://support.microsoft.com/kb/110093'.

The application development part of this reference assumes a good
working knowledge of C, general DBMS knowledge, and finally, but not
least, familiarity with MySQL. For more information about MySQL
functionality and its syntax, refer to `http://dev.mysql.com/doc/'.

Typically, you need to install Connector/ODBC only on Windows machines.
For Unix and Mac OS X you can use the native MySQL network or named
pipe to communicate with your MySQL database. You may need
Connector/ODBC for Unix or Mac OS X if you have an application that
requires an ODBC interface to communicate with the database.
Applications that require ODBC to communicate with MySQL include
ColdFusion, Microsoft Office, and Filemaker Pro.

*Key topics:*

   * For help installing Connector/ODBC see *Note myodbc-installation::.

   * For information on the configuration options, see *Note
     myodbc-configuration-connection-parameters::.

   * For more information on connecting to a MySQL database from a
     Windows host using Connector/ODBC see *Note
     myodbc-examples-walkthrough::.

   * If you want to use Microsoft Access as an interface to a MySQL
     database using Connector/ODBC see *Note
     myodbc-examples-tools-with-access::.

   * General tips on using Connector/ODBC, including obtaining the last
     auto-increment ID see *Note myodbc-usagenotes-functionality::.

   * For tips and common questions on using Connector/ODBC with
     specific application see *Note myodbc-usagenotes-apptips::.

   * For a general list of Frequently Asked Questions see *Note
     myodbc-errors::.

   * Additional support when using Connector/ODBC is available, see
     *Note myodbc-support::.

MySQL Enterprise

MySQL Enterprise subscribers will find more information about MySQL and
ODBC in the Knowledge Base articles about ODBC
(https://kb.mysql.com/search.php?cat=search&category=9). Access to the
MySQL Knowledge Base collection of articles is one of the advantages of
subscribing to MySQL Enterprise. For more information see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: myodbc-versions,  Next: myodbc-introduction,  Prev: myodbc-connector,  Up: myodbc-connector

30.1.1 Connector/ODBC Versions
------------------------------

There are currently two version of Connector/ODBC available:

   * Connector/ODBC 5.1, currently in GA status, is a partial rewrite
     of the of the 3.51 code base and is designed to work all versions
     of MySQL from 4.1. Connector/ODBC 5.1 will be a complete
     implementation of the ODBC Core interface,plus more Level 1 and
     Level 2 functionality of the ODBC specification than that
     currently supported by Connector/ODBC 3.51. See *Note
     connector-odbc-roadmap::.

     Connector/ODBC 5.1 also includes the following changes and
     improvements over the 3.51 release:

        * Improved support on Windows 64-bit platforms.

        * Full Unicode support at the driver level. This includes
          support for the `SQL_WCHAR' datatype, and support for Unicode
          login, password and DSN configurations. For more
          information,. see Microsoft Knowledgebase Article #716246
          (http://msdn2.microsoft.com/en-us/library/ms716246.aspx).

        * Support for the `SQL_NUMERIC_STRUCT' datatype, which provides
          easier access to the precise definition of numeric values.
          For more information, see Microsoft Knowledgebase Article
          #714556
          (http://msdn2.microsoft.com/en-us/library/ms714556.aspx)

        * Native Windows setup library. This replaces the Qt library
          based interface for configuring DSN information within the
          ODBC Data Sources application.

        * Support for the ODBC descriptor, which improves the handling
          and metadata of columns and parameter data. For more
          information, see Microsoft Knowledgebase Article #716339
          (http://msdn2.microsoft.com/en-us/library/ms716339.aspx).

   * Connector/ODBC 3.51 is the current release of the 32-bit ODBC
     driver, also known as the MySQL ODBC 3.51 driver.  Connector/ODBC
     3.51 has support for ODBC 3.5x specification level 1 (complete
     core API + level 2 features) in order to continue to provide all
     functionality of ODBC for accessing MySQL.

The manual for versions of Connector/ODBC older than 3.51 can be
located in the corresponding binary or source distribution. Please note
that versions of Connector/ODBC earlier than the 3.51 revision were not
fully compliant with the ODBC specification.

*Note*:

Development on Connector/ODBC 5.0 was stopped due to development
issues. Connector/ODBC 5.1 is now the current development release.

*Note*:

From this section onward, the primary focus of this guide is the
Connector/ODBC 3.51 and Connector/ODBC 5.1 drivers.

*Note*:

Version numbers for MySQL products are formatted as X.X.X.  However,
Windows tools (Control Panel, properties display) may show the version
numbers as XX.XX.XX. For example, the official MySQL formatted version
number 5.0.9 may be displayed by Windows tools as 5.00.09. The two
versions are the same; only the number display format is different.


File: manual.info,  Node: myodbc-introduction,  Next: myodbc-installation,  Prev: myodbc-versions,  Up: myodbc-connector

30.1.2 Connector/ODBC Introduction
----------------------------------

* Menu:

* connector-odbc-roadmap::       Connector/ODBC Roadmap
* myodbc-general-information::   General Information About ODBC and Connector/ODBC

ODBC (Open Database Connectivity) provides a way for client programs to
access a wide range of databases or data sources. ODBC is a
standardized API that allows connections to SQL database servers. It
was developed according to the specifications of the SQL Access Group
and defines a set of function calls, error codes, and data types that
can be used to develop database-independent applications. ODBC usually
is used when database independence or simultaneous access to different
data sources is required.

For more information about ODBC, refer to
`http://support.microsoft.com/kb/110093'.


File: manual.info,  Node: connector-odbc-roadmap,  Next: myodbc-general-information,  Prev: myodbc-introduction,  Up: myodbc-introduction

30.1.2.1 Connector/ODBC Roadmap
...............................

Connector/ODBC 5.1 is currently in development and will be a complete
implementation of the ODBC Core interface,plus more Level 1 and Level 2
functionality of the ODBC specification than that currently supported
by Connector/ODBC 3.51.

The following functionality was added or changed as part of 5.1:

   * Add support for SQL_NUMERIC_STRUCT: MSDN Article 714556
     (http://msdn2.microsoft.com/en-us/library/ms714556.aspx).

   * Replace installer library with new implementation (from v5 tree).

   * Implement native Windows setup library.

   * Implement SQLCancel() (Bug#15601 (http://bugs.mysql.com/15601)):
     MSDN Article 714112
     (http://msdn2.microsoft.com/en-us/library/ms714112.aspx).

The following functionality will be added in a version after 5.1:

   * Implement native Mac OS X setup library.

   * Replace OPTIONS flags with individual DSN settings (but support
     OPTIONS for backwards-compatibility).

   * Fix support for SQLBIGINT (Bug#28887
     (http://bugs.mysql.com/28887)): MSDN Article 714121
     (http://msdn2.microsoft.com/en-us/library/ms714121.aspx).

   * Make diagnostics support standards-compliant: MSDN Article 711021
     (http://msdn2.microsoft.com/en-us/library/ms711021.aspx).

   * Add support for SQL_ATTR_METADATA_ID: MSDN Article 716447
     (http://msdn2.microsoft.com/en-us/library/ms716447.aspx).

   * Implement SQLBrowseConnect(): MSDN Article 714565
     (http://msdn2.microsoft.com/en-us/library/ms714565.aspx), MSDN
     Article 712446
     (http://msdn2.microsoft.com/en-us/library/ms712446.aspx).

   * Implement arrays of parameters: MSDN Article 711818
     (http://msdn2.microsoft.com/en-us/library/ms711818.aspx).


File: manual.info,  Node: myodbc-general-information,  Prev: connector-odbc-roadmap,  Up: myodbc-introduction

30.1.2.2 General Information About ODBC and Connector/ODBC
..........................................................

* Menu:

* myodbc-architecture::          Connector/ODBC Architecture
* myodbc-driver-manager::        ODBC Driver Managers

Open Database Connectivity (ODBC) is a widely accepted
application-programming interface (API) for database access. It is
based on the Call-Level Interface (CLI) specifications from X/Open and
ISO/IEC for database APIs and uses Structured Query Language (SQL) as
its database access language.

A survey of ODBC functions supported by Connector/ODBC is given at
*Note myodbc-reference-api::. For general information about ODBC, see
`http://support.microsoft.com/kb/110093'.


File: manual.info,  Node: myodbc-architecture,  Next: myodbc-driver-manager,  Prev: myodbc-general-information,  Up: myodbc-general-information

30.1.2.3 Connector/ODBC Architecture
....................................

The Connector/ODBC architecture is based on five components, as shown
in the following diagram:

Connector/ODBC Architecture

   * *Application:*

     The Application uses the ODBC API to access the data from the
     MySQL server. The ODBC API in turn uses the communicates with the
     Driver Manager. The Application communicates with the Driver
     Manager using the standard ODBC calls. The Application does not
     care where the data is stored, how it is stored, or even how the
     system is configured to access the data. It needs to know only the
     Data Source Name (DSN).

     A number of tasks are common to all applications, no matter how
     they use ODBC. These tasks are:

        * Selecting the MySQL server and connecting to it

        * Submitting SQL statements for execution

        * Retrieving results (if any)

        * Processing errors

        * Committing or rolling back the transaction enclosing the SQL
          statement

        * Disconnecting from the MySQL server

     Because most data access work is done with SQL, the primary tasks
     for applications that use ODBC are submitting SQL statements and
     retrieving any results generated by those statements.

   * *Driver manager:*

     The Driver Manager is a library that manages communication between
     application and driver or drivers. It performs the following tasks:

        * Resolves Data Source Names (DSN). The DSN is a configuration
          string that identifies a given database driver, database,
          database host and optionally authentication information that
          enables an ODBC application to connect to a database using a
          standardized reference.

          Because the database connectivity information is identified
          by the DSN, any ODBC compliant application can connect to the
          data source using the same DSN reference. This eliminates the
          need to separately configure each application that needs
          access to a given database; instead you instruct the
          application to use a pre-configured DSN.

        * Loading and unloading of the driver required to access a
          specific database as defined within the DSN. For example, if
          you have configured a DSN that connects to a MySQL database
          then the driver manager will load the Connector/ODBC driver
          to enable the ODBC API to communicate with the MySQL host.

        * Processes ODBC function calls or passes them to the driver
          for processing.

   * *Connector/ODBC Driver:*

     The Connector/ODBC driver is a library that implements the
     functions supported by the ODBC API. It processes ODBC function
     calls, submits SQL requests to MySQL server, and returns results
     back to the application. If necessary, the driver modifies an
     application's request so that the request conforms to syntax
     supported by MySQL.

   * *DSN Configuration:*

     The ODBC configuration file stores the driver and database
     information required to connect to the server. It is used by the
     Driver Manager to determine which driver to be loaded according to
     the definition in the DSN. The driver uses this to read connection
     parameters based on the DSN specified. For more information, *Note
     myodbc-configuration::.

   * *MySQL Server:*

     The MySQL database where the information is stored. The database
     is used as the source of the data (during queries) and the
     destination for data (during inserts and updates).


File: manual.info,  Node: myodbc-driver-manager,  Prev: myodbc-architecture,  Up: myodbc-general-information

30.1.2.4 ODBC Driver Managers
.............................

An ODBC Driver Manager is a library that manages communication between
the ODBC-aware application and any drivers. Its main functionality
includes:

   * Resolving Data Source Names (DSN).

   * Driver loading and unloading.

   * Processing ODBC function calls or passing them to the driver.

Both Windows and Mac OS X include ODBC driver managers with the
operating system. Most ODBC Driver Manager implementations also include
an administration application that makes the configuration of DSN and
drivers easier. Examples and information on these managers, including
Unix ODBC driver managers are listed below:

   * Microsoft Windows ODBC Driver Manager (`odbc32.dll'),
     `http://support.microsoft.com/kb/110093'.

   * Mac OS X includes `ODBC Administrator', a GUI application that
     provides a simpler configuration mechanism for the Unix iODBC
     Driver Manager. You can configure DSN and driver information
     either through ODBC Administrator or through the iODBC
     configuration files.  This also means that you can test ODBC
     Administrator configurations using the `iodbctest' command.
     `http://www.apple.com'.

   * `unixODBC' Driver Manager for Unix (`libodbc.so'). See
     `http://www.unixodbc.org', for more information. The `unixODBC'
     Driver Manager includes the Connector/ODBC driver 3.51 in the
     installation package, starting with version `unixODBC' 2.1.2.

   * `iODBC' ODBC Driver Manager for Unix (`libiodbc.so'), see
     `http://www.iodbc.org', for more information.


File: manual.info,  Node: myodbc-installation,  Next: myodbc-configuration,  Prev: myodbc-introduction,  Up: myodbc-connector

30.1.3 Connector/ODBC Installation
----------------------------------

* Menu:

* myodbc-installation-binary-windows::  Installing Connector/ODBC from a Binary Distribution on Windows
* myodbc-installation-binary-unix::  Installing Connector/ODBC from a Binary Distribution on Unix
* myodbc-installation-binary-macosx::  Installing Connector/ODBC from a Binary Distribution on Mac OS X
* myodbc-installation-source-windows::  Installing Connector/ODBC from a Source Distribution on Windows
* myodbc-installation-source-unix::  Installing Connector/ODBC from a Source Distribution on Unix
* myodbc-installation-source-development::  Installing Connector/ODBC from the Development Source Tree

You can install the Connector/ODBC drivers using two different methods,
a binary installation and a source installation. The binary
installation is the easiest and most straightforward method of
installation. Using the source installation methods should only be
necessary on platforms where a binary installation package is not
available, or in situations where you want to customize or modify the
installation process or Connector/ODBC drivers before installation.

*Where to Get Connector/ODBC*

MySQL AB distributes all its products under the General Public License
(GPL). You can get a copy of the latest version of Connector/ODBC
binaries and sources from the MySQL AB Web site
`http://dev.mysql.com/downloads/'.

For more information about Connector/ODBC, visit
`http://www.mysql.com/products/myodbc/'.

For more information about licensing, visit
`http://www.mysql.com/company/legal/licensing/'.

*Supported Platforms*

Connector/ODBC can be used on all major platforms supported by MySQL.
You can install it on:

   * Windows 95, 98, Me, NT, 2000, XP, and 2003

   * All Unix-like Operating Systems, including: AIX, Amiga, BSDI, DEC,
     FreeBSD, HP-UX 10/11, Linux, NetBSD, OpenBSD, OS/2, SGI Irix,
     Solaris, SunOS, SCO OpenServer, SCO UnixWare, Tru64 Unix

   * Mac OS X and Mac OS X Server

Using a binary distribution offers the most straightforward method for
installing Connector/ODBC. If you want more control over the driver,
the installation location and or to customize elements of the driver
you will need to build and install from the source.

If a binary distribution is not available for a particular platform
build the driver from the original source code. You can contribute the
binaries you create to MySQL by sending a mail message to
<myodbc@lists.mysql.com>, so that it becomes available for other users.

For further instructions:

Platform               Binary                 Source
Windows                *Note Installation     *Note Build
                       Instructions:          Instructions:
                       myodbc-installation-binary-windows.myodbc-installation-source-windows.
Unix/Linux             *Note Installation     *Note Build
                       Instructions:          Instructions:
                       myodbc-installation-binary-unix.myodbc-installation-source-unix.
Mac OS X               *Note Installation     
                       Instructions:          
                       myodbc-installation-binary-macosx.


File: manual.info,  Node: myodbc-installation-binary-windows,  Next: myodbc-installation-binary-unix,  Prev: myodbc-installation,  Up: myodbc-installation

30.1.3.1 Installing Connector/ODBC from a Binary Distribution on Windows
........................................................................

* Menu:

* myodbc-installation-binary-windows-installer::  Installing the Windows Connector/ODBC Driver using an installer
* myodbc-installation-binary-windows-dll::  Installing the Windows Connector/ODBC Driver using the Zipped DLL package

Before installing the Connector/ODBC drivers on Windows you should
ensure that your Microsoft Data Access Components (MDAC) are up to
date. You can obtain the latest version from the Microsoft Data Access
and Storage (http://support.microsoft.com/kb/110093) Web site.

There are three available distribution types to use when installing for
Windows. The contents in each case are identical, it is only the
installation method which is different.

   * Zipped installer consists of a Zipped package containing a
     standalone installation application. To install from this package,
     you must unzip the installer, and then run the installation
     application. See *Note
     myodbc-installation-binary-windows-installer:: to complete the
     installation.

   * MSI installer, an installation file that can be used with the
     installer included in Windows 2000, Windows XP and Windows Server
     2003. See *Note myodbc-installation-binary-windows-installer:: to
     complete the installation.

   * Zipped DLL package, containing the DLL files that need must be
     manually installed. See *Note
     myodbc-installation-binary-windows-dll:: to complete the
     installation.

*Note*:

An OLEDB/ODBC driver for Windows 64-bit is available from Microsoft
Downloads
(http://www.microsoft.com/downloads/details.aspx?FamilyID=000364db-5e8b-44a8-b9be-ca44d18b059b&displaylang=en).


File: manual.info,  Node: myodbc-installation-binary-windows-installer,  Next: myodbc-installation-binary-windows-dll,  Prev: myodbc-installation-binary-windows,  Up: myodbc-installation-binary-windows

30.1.3.2 Installing the Windows Connector/ODBC Driver using an installer
........................................................................

The installer packages offer a very simple method for installing the
Connector/ODBC drivers. If you have downloaded the zipped installer
then you must extract the installer application. The basic installation
process is identical for both installers.

You should follow these steps to complete the installation:

  1. Double click on the standalone installer that you extracted, or
     the MSI file you downloaded.

  2. The MySQL Connector/ODBC 3.51 - Setup Wizard will start.  Click
     the `Next' button to begin the installation process.

     Connector/ODBC Windows Installer - Welcome

  3. You will need to choose the installation type. The Typical
     installation provides the standard files you will need to connect
     to a MySQL database using ODBC. The Complete option installs all
     the available files, including debug and utility components. It is
     recommended you choose one of these two options to complete the
     installation. If choose one of these methods, click `Next' and
     then proceed to step 5.

     You may also choose a Custom installation, which enables you to
     select the individual components that you want to install. You
     have chosen this method, click `Next' and then proceed to step 4.

     Connector/ODBC Windows Installer - Choosing a Setup type welcome

  4. If you have chosen a custom installation, use the pop-ups to
     select which components to install and then click `Next' to
     install the necessary files.

     Connector/ODBC Windows Installer - Custom Installation welcome

  5. Once the files have copied to your machine, the installation is
     complete. Click `Finish' to exit the installer.

     Connector/ODBC Windows Installer - Completion welcome

Now the installation is complete, you can continue to configure your
ODBC connections using *Note myodbc-configuration::.


File: manual.info,  Node: myodbc-installation-binary-windows-dll,  Prev: myodbc-installation-binary-windows-installer,  Up: myodbc-installation-binary-windows

30.1.3.3 Installing the Windows Connector/ODBC Driver using the Zipped DLL package
..................................................................................

If you have downloaded the Zipped DLL package then you must install the
individual files required for Connector/ODBC operation manually. Once
you have unzipped the installation files, you can either perform this
operation by hand, executing each statement individually, or you can
use the included Batch file to perform an installation to the default
locations.

To install using the Batch file:

  1. Unzip the Connector/ODBC Zipped DLL package.

  2. Open a Command Prompt.

  3. Change to the directory created when you unzipped the
     Connector/ODBC Zipped DLL package.

  4. Run `Install.bat:'

          C:\> Install.bat

     This will copy the necessary files into the default location, and
     then register the Connector/ODBC driver with the Windows ODBC
     manager.

If you want to copy the files to an alternative location - for example,
to run or test different versions of the Connector/ODBC driver on the
same machine, then you must copy the files by hand. It is however not
recommended to install these files in a non-standard location. To copy
the files by hand to the default installation location use the following
steps:

  1. Unzip the Connector/ODBC Zipped DLL package.

  2. Open a Command Prompt.

  3. Change to the directory created when you unzipped the
     Connector/ODBC Zipped DLL package.

  4. Copy the library files to a suitable directory. The default is to
     copy them into the default Windows system directory
     `\Windows\System32':

          C:\> copy lib\myodbc3S.dll \Windows\System32
          C:\> copy lib\myodbc3S.lib \Windows\System32
          C:\> copy lib\myodbc3.dll \Windows\System32
          C:\> copy lib\myodbc3.lib \Windows\System32

  5. Copy the Connector/ODBC tools. These must be placed into a
     directory that is in the system `PATH'.  The default is to install
     these into the Windows system directory `\Windows\System32':

          C:\> copy bin\myodbc3i.exe \Windows\System32
          C:\> copy bin\myodbc3m.exe \Windows\System32
          C:\> copy bin\myodbc3c.exe \Windows\System32

  6. Optionally copy the help files. For these files to be accessible
     through the help system, they must be installed in the Windows
     system directory:

          C:\> copy doc\*.hlp \Windows\System32

  7. Finally, you must register the Connector/ODBC driver with the ODBC
     manager:

          C:\> myodbc3i -a -d -t"MySQL ODBC 3.51 Driver;\
            DRIVER=myodbc3.dll;SETUP=myodbc3S.dll"

     You must change the references to the DLL files and command
     location in the above statement if you have not installed these
     files into the default location.


File: manual.info,  Node: myodbc-installation-binary-unix,  Next: myodbc-installation-binary-macosx,  Prev: myodbc-installation-binary-windows,  Up: myodbc-installation

30.1.3.4 Installing Connector/ODBC from a Binary Distribution on Unix
.....................................................................

* Menu:

* myodbc-installation-binary-unix-tarball::  Installing Connector/ODBC from a Binary Tarball Distribution
* myodbc-installation-binary-unix-rpm::  Installing Connector/ODBC from an RPM Distribution

There are two methods available for installing Connector/ODBC on Unix
from a binary distribution. For most Unix environments you will need to
use the tarball distribution. For Linux systems, there is also an RPM
distribution available.


File: manual.info,  Node: myodbc-installation-binary-unix-tarball,  Next: myodbc-installation-binary-unix-rpm,  Prev: myodbc-installation-binary-unix,  Up: myodbc-installation-binary-unix

30.1.3.5 Installing Connector/ODBC from a Binary Tarball Distribution
.....................................................................

To install the driver from a tarball distribution (`.tar.gz' file),
download the latest version of the driver for your operating system and
follow these steps that demonstrate the process using the Linux version
of the tarball:

     shell> su root
     shell> gunzip mysql-connector-odbc-3.51.11-i686-pc-linux.tar.gz
     shell> tar xvf mysql-connector-odbc-3.51.11-i686-pc-linux.tar
     shell> cd mysql-connector-odbc-3.51.11-i686-pc-linux

Read the installation instructions in the `INSTALL-BINARY' file and
execute these commands.

     shell> cp libmyodbc* /usr/local/lib
     shell> cp odbc.ini /usr/local/etc
     shell> export ODBCINI=/usr/local/etc/odbc.ini

Then proceed on to *Note myodbc-configuration-dsn-unix::, to configure
the DSN for Connector/ODBC. For more information, refer to the
`INSTALL-BINARY' file that comes with your distribution.


File: manual.info,  Node: myodbc-installation-binary-unix-rpm,  Prev: myodbc-installation-binary-unix-tarball,  Up: myodbc-installation-binary-unix

30.1.3.6 Installing Connector/ODBC from an RPM Distribution
...........................................................

To install or upgrade Connector/ODBC from an RPM distribution on Linux,
simply download the RPM distribution of the latest version of
Connector/ODBC and follow the instructions below.  Use `su root' to
become `root', then install the RPM file.

If you are installing for the first time:

     shell> su root
      shell> rpm -ivh mysql-connector-odbc-3.51.12.i386.rpm

If the driver exists, upgrade it like this:

     shell> su root
     shell> rpm -Uvh mysql-connector-odbc-3.51.12.i386.rpm

If there is any dependency error for MySQL client library,
`libmysqlclient', simply ignore it by supplying the `--nodeps' option,
and then make sure the MySQL client shared library is in the path or set
through `LD_LIBRARY_PATH'.

This installs the driver libraries and related documents to
`/usr/local/lib' and `/usr/share/doc/MyODBC', respectively.  Proceed
onto *Note myodbc-configuration-dsn-unix::.

To *uninstall* the driver, become `root' and execute an `rpm' command:

     shell> su root
     shell> rpm -e mysql-connector-odbc


File: manual.info,  Node: myodbc-installation-binary-macosx,  Next: myodbc-installation-source-windows,  Prev: myodbc-installation-binary-unix,  Up: myodbc-installation

30.1.3.7 Installing Connector/ODBC from a Binary Distribution on Mac OS X
.........................................................................

Mac OS X is based on the FreeBSD operating system, and you can normally
use the MySQL network port for connecting to MySQL servers on other
hosts. Installing the Connector/ODBC driver enables you to connect to
MySQL databases on any platform through the ODBC interface. You should
only need to install the Connector/ODBC driver when your application
requires an ODBC interface. Applications that require or can use ODBC
(and therefore the Connector/ODBC driver) include ColdFusion, Filemaker
Pro, 4th Dimension and many other applications.

Mac OS X includes its own ODBC manager, based on the `iODBC' manager.
Mac OS X includes an administration tool that provides easier
administration of ODBC drivers and configuration, updating the
underlying `iODBC' configuration files.

The method for installing Connector/ODBC on Mac OS X depends on the
version on Connector/ODBC you are using. For Connector/ODBC 3.51.14 and
later, the package is provided as a compress tar archive that you must
manually install. For Connector/ODBC 3.51.13 and earlier the software
was provided on a compressed disk image (`.dmg') file and included an
installer.

In either case, the driver is designed to work with the iODBC driver
manager included with Mac OS X.

To install Connector/ODBC 3.51.14 and later:

  1. Download the installation file. Note that versions are available
     for both PowerPC and Intel platforms.

  2. Extract the archive:

          $ tar zxf mysql-connector-odbc-3.51.16-osx10.4-x86-32bit.tar.gz

  3. The directory created will contain two subdirectories, `lib' and
     `bin'. You need to copy these to a suitable location such as
     `/usr/local':

          $ cp bin/* /usr/local/bin
          $ cp lib/* /usr/local/lib

  4. Finally, you must register the driver with iODBC using the
     `myodbc3i' tool you just installed:

          $ myodbc3i -a -d -t"MySQL ODBC 3.51 Driver;Driver=/usr/local/lib/libmyodbc3.so;Setup=/usr/local/lib/libmyodbc3S.so"

You can verify the installed drivers either by using the ODBC
Administrator application or the `myodbc3i' utility:

     $ myodbc3i -q -d

To install Connector/ODBC 3.51.13 and earlier, follow these steps:

  1. Download the file to your computer and double-click on the
     downloaded image file.

  2. Within the disk image you will find an installer package (with the
     `.pkg' extension). Double click on this file to start the Mac OS X
     installer.

  3. You will be presented with the installer welcome message.  Click
     the `Continue' button to begin the installation process.

     Connector/ODBC Mac OS X Installer - Installer welcome

  4. Please take the time to read the Important Information as it
     contains guidance on how to complete the installation process.
     Once you have read the notice and collected the necessary
     information, click `Continue'.

     Connector/ODBC Mac OS X Installer - Important Information

  5. Connector/ODBC drivers are made available under the GNU General
     Public License. Please read the license if you are not familiar
     with it before continuing installation. Click `Continue' to
     approve the license (you will be asked to confirm that decision)
     and continue the installation.

     Connector/ODBC Mac OS X Installer - License

  6. Choose a location to install the Connector/ODBC drivers and the
     ODBC Administrator application. You must install the files onto a
     drive with an operating system and you may be limited in the
     choices available. Select the drive you want to use, and then
     click `Continue'.

     Connector/ODBC Mac OS X Installer - Choosing a destination

  7. The installer will automatically select the files that need to be
     installed on your machine. Click `Install' to continue. The
     installer will copy the necessary files to your machine. A progress
     bar will be shown indicating the installation progress.

     Connector/ODBC Mac OS X Installer - Installation type

  8. When installation has been completed you will get a window like
     the one shown below. Click `Close' to close and quit the installer.

     Connector/ODBC Mac OS X Installer - Installation complete


File: manual.info,  Node: myodbc-installation-source-windows,  Next: myodbc-installation-source-unix,  Prev: myodbc-installation-binary-macosx,  Up: myodbc-installation

30.1.3.8 Installing Connector/ODBC from a Source Distribution on Windows
........................................................................

* Menu:

* myodbc-installation-source-windows-3-51-building::  Building Connector/ODBC 3.51
* myodbc-installation-source-windows-3-51-testing::  Testing

You should only need to install Connector/ODBC from source on Windows
if you want to change or modify the source or installation. If you are
unsure whether to install from source, please use the binary
installation detailed in *Note myodbc-installation-binary-windows::.

Installing Connector/ODBC from source on Windows requires a number of
different tools and packages:

   * MDAC, Microsoft Data Access SDK from
     `http://support.microsoft.com/kb/110093'.

   * Suitable C compiler, such as Microsoft Visual C++ or the C
     compiler included with Microsoft Visual Studio.

   * Compatible `make' tool. Microsoft's `nmake' is used in the
     examples in this section.

   * MySQL client libraries and include files from MySQL 4.0.0 or
     higher. (Preferably MySQL 4.0.16 or higher). This is required
     because Connector/ODBC uses new calls and structures that exist
     only starting from this version of the library. To get the client
     libraries and include files, visit
     `http://dev.mysql.com/downloads/'.


File: manual.info,  Node: myodbc-installation-source-windows-3-51-building,  Next: myodbc-installation-source-windows-3-51-testing,  Prev: myodbc-installation-source-windows,  Up: myodbc-installation-source-windows

30.1.3.9 Building Connector/ODBC 3.51
.....................................

Connector/ODBC source distributions include `Makefiles' that require the
`nmake' or other `make' utility. In the distribution, you can find
`Makefile' for building the release version and `Makefile_debug' for
building debugging versions of the driver libraries and DLLs.

To build the driver, use this procedure:

  1. Download and extract the sources to a folder, then change
     directory into that folder. The following command assumes the
     folder is named `myodbc3-src':

          C:\> cd myodbc3-src

  2. Edit `Makefile' to specify the correct path for the MySQL client
     libraries and header files. Then use the following commands to
     build and install the release version:

          C:\> nmake -f Makefile
          C:\> nmake -f Makefile install

     `nmake -f Makefile' builds the release version of the driver and
     places the binaries in subdirectory called `Release'.

     `nmake -f Makefile install' installs (copies) the driver DLLs and
     libraries (`myodbc3.dll', `myodbc3.lib') to your system directory.

  3. To build the debug version, use `Makefile_Debug' rather than
     `Makefile', as shown below:

          C:\> nmake -f Makefile_debug
          C:\> nmake -f Makefile_debug install

  4. You can clean and rebuild the driver by using:

          C:\> nmake -f Makefile clean
          C:\> nmake -f Makefile install

*Note*:

   * Make sure to specify the correct MySQL client libraries and header
     files path in the Makefiles (set the `MYSQL_LIB_PATH' and
     `MYSQL_INCLUDE_PATH' variables). The default header file path is
     assumed to be `C:\mysql\include'. The default library path is
     assumed to be `C:\mysql\lib\opt' for release DLLs and
     `C:\mysql\lib\debug' for debug versions.

   * For the complete usage of `nmake', visit
     `http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dv_vcce4/html/evgrfRunningNMAKE.asp'.

   * If you are using the Subversion tree for compiling, all
     Windows-specific `Makefiles' are named as `Win_Makefile*'.


File: manual.info,  Node: myodbc-installation-source-windows-3-51-testing,  Prev: myodbc-installation-source-windows-3-51-building,  Up: myodbc-installation-source-windows

30.1.3.10 Testing
.................

After the driver libraries are copied/installed to the system
directory, you can test whether the libraries are properly built by
using the samples provided in the `samples' subdirectory:

     C:\> cd samples
     C:\> nmake -f Makefile all


File: manual.info,  Node: myodbc-installation-source-unix,  Next: myodbc-installation-source-development,  Prev: myodbc-installation-source-windows,  Up: myodbc-installation

30.1.3.11 Installing Connector/ODBC from a Source Distribution on Unix
......................................................................

* Menu:

* myodbc-installation-source-unix-configure-options::  Typical `configure' Options
* myodbc-installation-source-unix-otheroptions::  Additional configure Options
* myodbc-installation-source-unix-building::  Building and Compilation
* myodbc-installation-source-unix-shared-libraries::  Building Shared Libraries
* myodbc-installation-source-unix-installing::  Installing Driver Libraries
* myodbc-installation-source-unix-testing::  Testing Connector/ODBC on Unix
* myodbc-installation-source-unix-macosx::  Building Connector/ODBC from Source on Mac OS X
* myodbc-installation-source-unix-hpux::  Building Connector/ODBC from Source on HP-UX
* myodbc-installation-source-unix-aix::  Building Connector/ODBC from Source on AIX

You need the following tools to build MySQL from source on Unix:

   * A working ANSI C++ compiler. `gcc' 2.95.2 or later, SGI C++, and
     SunPro C++ are some of the compilers that are known to work.

   * A good `make' program. GNU `make' is always recommended and is
     sometimes required.

   * MySQL client libraries and include files from MySQL 4.0.0 or
     higher. (Preferably MySQL 4.0.16 or higher). This is required
     because Connector/ODBC uses new calls and structures that exist
     only starting from this version of the library. To get the client
     libraries and include files, visit
     `http://dev.mysql.com/downloads/'.

     If you have built your own MySQL server and/or client libraries
     from source then you must have used the
     `--enable-thread-safe-client' option to `configure' when the
     libraries were built.

     You should also ensure that the `libmysqlclient' library were
     built and installed as a shared library.

   * A compatible ODBC manager must be installed. Connector/ODBC is
     known to work with the `iODBC' and `unixODBC' managers. See *Note
     myodbc-driver-manager::, for more information.

   * If you are using a character set that isn't compiled into the
     MySQL client library then you need to install the MySQL character
     definitions from the `charsets' directory into SHAREDIR (by
     default, `/usr/local/mysql/share/mysql/charsets').  These should
     be in place if you have installed the MySQL server on the same
     machine. See *Note charset::, for more information on character
     set support.

Once you have all the required files, unpack the source files to a
separate directory, you then have to run `configure' and build the
library using `make'.


File: manual.info,  Node: myodbc-installation-source-unix-configure-options,  Next: myodbc-installation-source-unix-otheroptions,  Prev: myodbc-installation-source-unix,  Up: myodbc-installation-source-unix

30.1.3.12 Typical `configure' Options
.....................................

The `configure' script gives you a great deal of control over how you
configure your Connector/ODBC build.  Typically you do this using
options on the `configure' command line. You can also affect
`configure' using certain environment variables. For a list of options
and environment variables supported by `configure', run this command:

     shell> ./configure --help

Some of the more commonly used `configure' options are described here:

  1. To compile Connector/ODBC, you need to supply the MySQL client
     include and library files path using the `--with-mysql-path=DIR'
     option, where DIR is the directory where MySQL is installed.

     MySQL compile options can be determined by running
     `DIR/bin/mysql_config'.

  2. Supply the standard header and library files path for your ODBC
     Driver Manager (`iODBC' or `unixODBC').

        * If you are using `iODBC' and `iODBC' is not installed in its
          default location (`/usr/local'), you might have to use the
          `--with-iodbc=DIR' option, where DIR is the directory where
          `iODBC' is installed.

          If the `iODBC' headers do not reside in `DIR/include', you
          can use the `--with-iodbc-includes=INCDIR' option to specify
          their location.

          The applies to libraries. If they are not in `DIR/lib', you
          can use the `--with-iodbc-libs=LIBDIR' option.

        * If you are using `unixODBC', use the `--with-unixODBC=DIR'
          option (case sensitive) to make `configure' look for
          `unixODBC' instead of `iODBC' by default, DIR is the
          directory where `unixODBC' is installed.

          If the `unixODBC' headers and libraries aren't located in
          `DIR/include' and `DIR/lib', use the
          `--with-unixODBC-includes=INCDIR' and
          `--with-unixODBC-libs=LIBDIR' options.

  3. You might want to specify an installation prefix other than
     `/usr/local'. For example, to install the Connector/ODBC drivers in
     `/usr/local/odbc/lib', use the `--prefix=/usr/local/odbc' option.

The final configuration command looks something like this:

     shell> ./configure --prefix=/usr/local \
              --with-iodbc=/usr/local \
              --with-mysql-path=/usr/local/mysql


File: manual.info,  Node: myodbc-installation-source-unix-otheroptions,  Next: myodbc-installation-source-unix-building,  Prev: myodbc-installation-source-unix-configure-options,  Up: myodbc-installation-source-unix

30.1.3.13 Additional configure Options
......................................

There are a number of other options that you need, or want, to set when
configuring the Connector/ODBC driver before it is built.

   * To link the driver with MySQL thread safe client libraries
     `libmysqlclient_r.so' or `libmysqlclient_r.a', you must specify
     the following `configure' option:

          --enable-thread-safe

     and can be disabled (default) using

          --disable-thread-safe

     This option enables the building of the driver thread-safe library
     `libmyodbc3_r.so' from by linking with MySQL thread-safe client
     library `libmysqlclient_r.so' (The extensions are OS dependent).

     If the compilation with the thread-safe option fails, it may be
     because the correct thread-libraries on the system could not be
     located. You should set the value of `LIBS' to point to the
     correct thread library for your system.

          LIBS="-lpthread" ./configure ..

   * You can enable or disable the shared and static versions of
     Connector/ODBC using these options:

          --enable-shared[=yes/no]
          --disable-shared
          --enable-static[=yes/no]
          --disable-static

   * By default, all the binary distributions are built as
     non-debugging versions (configured with `--without-debug').

     To enable debugging information, build the driver from source
     distribution and use the `--with-debug' option when you run
     `configure'.

   * This option is available only for source trees that have been
     obtained from the Subversion repository. This option does not
     apply to the packaged source distributions.

     By default, the driver is built with the `--without-docs' option.
     If you would like the documentation to be built, then execute
     `configure' with:

          --with-docs


File: manual.info,  Node: myodbc-installation-source-unix-building,  Next: myodbc-installation-source-unix-shared-libraries,  Prev: myodbc-installation-source-unix-otheroptions,  Up: myodbc-installation-source-unix

30.1.3.14 Building and Compilation
..................................

To build the driver libraries, you have to just execute `make'.

     shell> make

If any errors occur, correct them and continue the build process. If
you aren't able to build, then send a detailed email to
<myodbc@lists.mysql.com> for further assistance.


File: manual.info,  Node: myodbc-installation-source-unix-shared-libraries,  Next: myodbc-installation-source-unix-installing,  Prev: myodbc-installation-source-unix-building,  Up: myodbc-installation-source-unix

30.1.3.15 Building Shared Libraries
...................................

On most platforms, MySQL does not build or support `.so' (shared)
client libraries by default.  This is based on our experience of
problems when building shared libraries.

In cases like this, you have to download the MySQL distribution and
configure it with these options:

     --without-server --enable-shared

To build shared driver libraries, you must specify the
`--enable-shared' option for `configure'. By default, `configure' does
not enable this option.

If you have configured with the `--disable-shared' option, you can
build the `.so' file from the static libraries using the following
commands:

     shell> cd mysql-connector-odbc-3.51.01
     shell> make
     shell> cd driver
     shell> CC=/usr/bin/gcc \
               $CC -bundle -flat_namespace -undefined error \
               -o .libs/libmyodbc3-3.51.01.so \
               catalog.o connect.o cursor.o dll.o error.o execute.o \
               handle.o info.o misc.o myodbc3.o options.o prepare.o \
               results.o transact.o utility.o \
               -L/usr/local/mysql/lib/mysql/ \
               -L/usr/local/iodbc/lib/ \
               -lz -lc -lmysqlclient -liodbcinst

Make sure to change `-liodbcinst' to `-lodbcinst' if you are using
`unixODBC' instead of `iODBC', and configure the library paths
accordingly.

This builds and places the `libmyodbc3-3.51.01.so' file in the `.libs'
directory. Copy this file to the Connector/ODBC library installation
directory (`/usr/local/lib' (or the `lib' directory under the
installation directory that you supplied with the `--prefix').

     shell> cd .libs
     shell> cp libmyodbc3-3.51.01.so /usr/local/lib
     shell> cd /usr/local/lib
     shell> ln -s libmyodbc3-3.51.01.so libmyodbc3.so

To build the thread-safe driver library:

     shell> CC=/usr/bin/gcc \
               $CC -bundle -flat_namespace -undefined error
               -o .libs/libmyodbc3_r-3.51.01.so
               catalog.o connect.o cursor.o dll.o error.o execute.o
               handle.o info.o misc.o myodbc3.o options.o prepare.o
               results.o transact.o utility.o
               -L/usr/local/mysql/lib/mysql/
               -L/usr/local/iodbc/lib/
               -lz -lc -lmysqlclient_r -liodbcinst


File: manual.info,  Node: myodbc-installation-source-unix-installing,  Next: myodbc-installation-source-unix-testing,  Prev: myodbc-installation-source-unix-shared-libraries,  Up: myodbc-installation-source-unix

30.1.3.16 Installing Driver Libraries
.....................................

To install the driver libraries, execute the following command:

     shell> make install

That command installs one of the following sets of libraries:

For Connector/ODBC 3.51:

   * `libmyodbc3.so'

   * `libmyodbc3-3.51.01.so', where 3.51.01 is the version of the driver

   * `libmyodbc3.a'

For thread-safe Connector/ODBC 3.51:

   * `libmyodbc3_r.so'

   * `libmyodbc3-3_r.51.01.so'

   * `libmyodbc3_r.a'

For more information on build process, refer to the `INSTALL' file that
comes with the source distribution. Note that if you are trying to use
the `make' from Sun, you may end up with errors.  On the other hand,
GNU `gmake' should work fine on all platforms.


File: manual.info,  Node: myodbc-installation-source-unix-testing,  Next: myodbc-installation-source-unix-macosx,  Prev: myodbc-installation-source-unix-installing,  Up: myodbc-installation-source-unix

30.1.3.17 Testing Connector/ODBC on Unix
........................................

To run the basic samples provided in the distribution with the
libraries that you built, use the following command:

     shell> make test

Before running the tests, create the DSN 'myodbc3' in `odbc.ini' and
set the environment variable `ODBCINI' to the correct `odbc.ini' file;
and MySQL server is running. You can find a sample `odbc.ini' with the
driver distribution.

You can even modify the `samples/run-samples' script to pass the
desired DSN, UID, and PASSWORD values as the command-line arguments to
each sample.


File: manual.info,  Node: myodbc-installation-source-unix-macosx,  Next: myodbc-installation-source-unix-hpux,  Prev: myodbc-installation-source-unix-testing,  Up: myodbc-installation-source-unix

30.1.3.18 Building Connector/ODBC from Source on Mac OS X
.........................................................

To build the driver on Mac OS X (Darwin), make use of the following
`configure' example:

     shell> ./configure --prefix=/usr/local
               --with-unixODBC=/usr/local
               --with-mysql-path=/usr/local/mysql
               --disable-shared
               --enable-gui=no
               --host=powerpc-apple

The command assumes that the `unixODBC' and MySQL are installed in the
default locations. If not, configure accordingly.

On Mac OS X, `--enable-shared' builds `.dylib' files by default. You
can build `.so' files like this:

     shell> make
     shell> cd driver
     shell> CC=/usr/bin/gcc \
               $CC -bundle -flat_namespace -undefined error
               -o .libs/libmyodbc3-3.51.01.so *.o
               -L/usr/local/mysql/lib/
               -L/usr/local/iodbc/lib
               -liodbcinst -lmysqlclient -lz -lc

To build the thread-safe driver library:

     shell> CC=/usr/bin/gcc \
               $CC -bundle -flat_namespace -undefined error
               -o .libs/libmyodbc3-3.51.01.so *.o
               -L/usr/local/mysql/lib/
               -L/usr/local/iodbc/lib
               -liodbcinst -lmysqlclienti_r -lz -lc -lpthread

Make sure to change the `-liodbcinst' to `-lodbcinst' in case of using
`unixODBC' instead of `iODBC' and configure the libraries path
accordingly.

In Apple's version of GCC, both `cc' and `gcc' are actually symbolic
links to `gcc3'.

Copy this library to the `$prefix/lib' directory and symlink to
`libmyodbc3.so'.

You can cross-check the output shared-library properties using this
command:

     shell> otool -LD .libs/libmyodbc3-3.51.01.so


File: manual.info,  Node: myodbc-installation-source-unix-hpux,  Next: myodbc-installation-source-unix-aix,  Prev: myodbc-installation-source-unix-macosx,  Up: myodbc-installation-source-unix

30.1.3.19 Building Connector/ODBC from Source on HP-UX
......................................................

To build the driver on HP-UX 10.x or 11.x, make use of the following
`configure' example:

If using `cc':

     shell> CC="cc" \
               CFLAGS="+z" \
               LDFLAGS="-Wl,+b:-Wl,+s" \
               ./configure --prefix=/usr/local
               --with-unixodbc=/usr/local
               --with-mysql-path=/usr/local/mysql/lib/mysql
               --enable-shared
               --enable-thread-safe

If using `gcc':

     shell> CC="gcc" \
               LDFLAGS="-Wl,+b:-Wl,+s" \
               ./configure --prefix=/usr/local
               --with-unixodbc=/usr/local
               --with-mysql-path=/usr/local/mysql
               --enable-shared
               --enable-thread-safe

Once the driver is built, cross-check its attributes using `chatr
.libs/libmyodbc3.sl' to determine whether you need to have set the
MySQL client library path using the `SHLIB_PATH' environment variable.
For static versions, ignore all shared-library options and run
`configure' with the `--disable-shared' option.


File: manual.info,  Node: myodbc-installation-source-unix-aix,  Prev: myodbc-installation-source-unix-hpux,  Up: myodbc-installation-source-unix

30.1.3.20 Building Connector/ODBC from Source on AIX
....................................................

To build the driver on AIX, make use of the following `configure'
example:

     shell> ./configure --prefix=/usr/local
               --with-unixodbc=/usr/local
               --with-mysql-path=/usr/local/mysql
               --disable-shared
               --enable-thread-safe

*Note*:

For more information about how to build and set up the static and
shared libraries across the different platforms refer to ' Using static
and shared libraries across platforms
(http://www.fortran-2000.com/ArnaudRecipes/sharedlib.html)'.


File: manual.info,  Node: myodbc-installation-source-development,  Prev: myodbc-installation-source-unix,  Up: myodbc-installation

30.1.3.21 Installing Connector/ODBC from the Development Source Tree
....................................................................

*Caution*:

You should read this section only if you are interested in helping us
test our new code. If you just want to get MySQL Connector/ODBC up and
running on your system, you should use a standard release distribution.

To be able to access the Connector/ODBC source tree, you must have
Subversion installed. Subversion is freely available from
`http://subversion.tigris.org/'.

To build from the source trees, you need the following tools:

   * autoconf 2.52 (or newer)

   * automake 1.4 (or newer)

   * libtool 1.4 (or newer)

   * m4

The most recent development source tree is available from our public
Subversion trees at `http://dev.mysql.com/tech-resources/sources.html'.

To checkout out the Connector/ODBC sources, change to the directory
where you want the copy of the Connector/ODBC tree to be stored, then
use the following command:

     shell> svn co http://svn.mysql.com/svnpublic/connector-odbc3

You should now have a copy of the entire Connector/ODBC source tree in
the directory `connector-odbc3'. To build from this source tree on Unix
or Linux follow these steps:

     shell> cd connector-odbc3
     shell> aclocal
     shell> autoheader
     shell> autoconf
     shell> automake;
     shell> ./configure  # Add your favorite options here
     shell> make

For more information on how to build, refer to the `INSTALL' file
located in the same directory.  For more information on options to
`configure', see *Note
myodbc-installation-source-unix-configure-options::

When the build is done, run `make install' to install the
Connector/ODBC 3.51 driver on your system.

If you have gotten to the `make' stage and the distribution does not
compile, please report it to <myodbc@lists.mysql.com>.

On Windows, make use of Windows Makefiles `WIN-Makefile' and
`WIN-Makefile_debug' in building the driver.  For more information, see
*Note myodbc-installation-source-windows::.

After the initial checkout operation to get the source tree, you should
run `svn update' periodically update your source according to the
latest version.


File: manual.info,  Node: myodbc-configuration,  Next: myodbc-examples,  Prev: myodbc-installation,  Up: myodbc-connector

30.1.4 Connector/ODBC Configuration
-----------------------------------

* Menu:

* myodbc-configuration-dsn::     Data Source Names
* myodbc-configuration-connection-parameters::  Connector/ODBC Connection Parameters
* myodbc-configuration-dsn-windows::  Configuring a Connector/ODBC DSN on Windows
* myodbc-configuration-dsn-macosx::  Configuring a Connector/ODBC DSN on Mac OS X
* myodbc-configuration-dsn-unix::  Configuring a Connector/ODBC DSN on Unix
* myodbc-configuration-connection-without-dsn::  Connecting Without a Predefined DSN
* myodbc-configuration-connection-pooling::  ODBC Connection Pooling
* myodbc-configuration-trace::   Getting an ODBC Trace File

Before you connect to a MySQL database using the Connector/ODBC driver
you must configure an ODBC _Data Source Name_. The DSN associates the
various configuration parameters required to communicate with a
database to a specific name. You use the DSN in an application to
communicate with the database, rather than specifying individual
parameters within the application itself. DSN information can be user
specific, system specific, or provided in a special file. ODBC data
source names are configured in different ways, depending on your
platform and ODBC driver.


File: manual.info,  Node: myodbc-configuration-dsn,  Next: myodbc-configuration-connection-parameters,  Prev: myodbc-configuration,  Up: myodbc-configuration

30.1.4.1 Data Source Names
..........................

A Data Source Name associates the configuration parameters for
communicating with a specific database. Generally a DSN consists of the
following parameters:

   * Name

   * Hostname

   * Database Name

   * Login

   * Password

In addition, different ODBC drivers, including Connector/ODBC, may
accept additional driver-specific options and parameters.

There are three types of DSN:

   * A _System DSN_ is a global DSN definition that is available to any
     user and application on a particular system. A System DSN can
     normally only be configured by a systems administrator, or by a
     user who has specific permissions that let them create System DSNs.

   * A _User DSN_ is specific to an individual user, and can be used to
     store database connectivity information that the user regularly
     uses.

   * A _File DSN_ uses a simple file to define the DSN configuration.
     File DSNs can be shared between users and machines and are
     therefore more practical when installing or deploying DSN
     information as part of an application across many machines.

DSN information is stored in different locations depending on your
platform and environment.


File: manual.info,  Node: myodbc-configuration-connection-parameters,  Next: myodbc-configuration-dsn-windows,  Prev: myodbc-configuration-dsn,  Up: myodbc-configuration

30.1.4.2 Connector/ODBC Connection Parameters
.............................................

You can specify the parameters in the following tables for
Connector/ODBC when configuring a DSN. Users on Windows can use the
Options and Advanced panels when configuring a DSN to set these
parameters; see the table for information on which options relate to
which fields and checkboxes. On Unix and Mac OS X, use the parameter
name and value as the keyword/value pair in the DSN configuration.
Alternatively, you can set these parameters within the
`InConnectionString' argument in the `SQLDriverConnect()' call.

Parameter   Default Value  Comment
`user'      ODBC           The username used to connect to MySQL.
`uid'       ODBC           Synonymous with `user'. Added in 3.51.16.
`server'    `localhost'    The hostname of the MySQL server.
`database'                 The default database.
`option'    0              Options that specify how Connector/ODBC should
                           work. See below.
`port'      3306           The TCP/IP port to use if `server' is not
                           `localhost'.
`stmt'                     A statement to execute when connecting to
                           MySQL.
`password'                 The password for the `user' account on
                           `server'.
`pwd'                      Synonymous with `password'. Added in 3.51.16.
`socket'                   The Unix socket file or Windows named pipe to
                           connect to if `server' is `localhost'.
`sslca'                    The path to a file with a list of trust SSL
                           CAs. Added in 3.51.16.
`sslcapath'                The path to a directory that contains trusted
                           SSL CA certificates in PEM format. Added in
                           3.51.16.
`sslcert'                  The name of the SSL certificate file to use
                           for establishing a secure connection. Added in
                           3.51.16.
`sslcipher'                A list of allowable ciphers to use for SSL
                           encryption. The cipher list has the same
                           format as the `openssl ciphers' command Added
                           in 3.51.16.
`sslkey'                   The name of the SSL key file to use for
                           establishing a secure connection. Added in
                           3.51.16.
`charset'                  The character set to use for the connection.
                           Added in 3.51.17.
`sslverify'                If set to 1, the SSL certificate will be
                           verified when used with the MySQL connection.
                           If not set, then the default behaviour is to
                           ignore SSL certificate verification.

*Note*:

The SSL configuration parameters can also be automatically loaded from
a `my.ini' or `my.cnf' file.

The `option' argument is used to tell Connector/ODBC that the client
isn't 100% ODBC compliant. On Windows, you normally select options by
toggling the checkboxes in the connection screen, but you can also
select them in the `option' argument. The following options are listed
in the order in which they appear in the Connector/ODBC connect screen:

*Value* *Flagname*     *GUI Option*   *Description*
1       `FLAG_FIELD_LENGTH'Don't          The client can't handle that
                       Optimize       Connector/ODBC returns the real
                       Column Width   width of a column. This option was
                                      removed in 3.51.18.
2       `FLAG_FOUND_ROWS'Return         The client can't handle that MySQL
                       Matching Rows  returns the true value of affected
                                      rows. If this flag is set, MySQL
                                      returns `found rows' instead. You
                                      must have MySQL 3.21.14 or newer to
                                      get this to work.
4       `FLAG_DEBUG'   Trace Driver   Make a debug log in `C:\myodbc.log'
                       Calls To       on Windows, or `/tmp/myodbc.log' on
                       myodbc.log     Unix variants.  This option was
                                      removed in Connector/ODBC 3.51.18.
8       `FLAG_BIG_PACKETS'Allow Big      Don't set any packet limit for
                       Results        results and bind parameters.
                                      Without this option, parameter
                                      binding will be truncated to 255
                                      characters.
16      `FLAG_NO_PROMPT'Don't Prompt   Don't prompt for questions even if
                       Upon Connect   driver would like to prompt.
32      `FLAG_DYNAMIC_CURSOR'Enable         Enable or disable the dynamic
                       Dynamic Cursor cursor support.
64      `FLAG_NO_SCHEMA'Ignore # in    Ignore use of database name in
                       Table Name     DB_NAME.TBL_NAME.COL_NAME.
128     `FLAG_NO_DEFAULT_CURSOR'User Manager   Force use of ODBC manager cursors
                       Cursors        (experimental).
256     `FLAG_NO_LOCALE'Don't Use Set  Disable the use of extended fetch
                       Locale         (experimental).
512     `FLAG_PAD_SPACE'Pad Char To    Pad `CHAR' columns to full column
                       Full Length    length.
1024    `FLAG_FULL_COLUMN_NAMES'Return Table   `SQLDescribeCol()' returns fully
                       Names for      qualified column names.
                       SQLDescribeCol 
2048    `FLAG_COMPRESSED_PROTO'Use            Use the compressed client/server
                       Compressed     protocol.
                       Protocol       
4096    `FLAG_IGNORE_SPACE'Ignore Space   Tell server to ignore space after
                       After          function name and before ``(''
                       Function Names (needed by PowerBuilder). This
                                      makes all function names keywords.
8192    `FLAG_NAMED_PIPE'Force Use of   Connect with named pipes to a
                       Named Pipes    `mysqld' server running on NT.
16384   `FLAG_NO_BIGINT'Change BIGINT  Change `BIGINT' columns to `INT'
                       Columns to Int columns (some applications can't
                                      handle `BIGINT').
32768   `FLAG_NO_CATALOG'No Catalog     Forces results from the catalog
                                      functions, such as `SQLTables', to
                                      always return `NULL' and the driver
                                      to report that catalogs are not
                                      supported.
65536   `FLAG_USE_MYCNF'Read Options   Read parameters from the `[client]'
                       From `my.cnf'  and `[odbc]' groups from `my.cnf'.
131072  `FLAG_SAFE'    Safe           Add some extra safety checks.
262144  `FLAG_NO_TRANSACTIONS'Disable        Disable transactions.
                       transactions   
524288  `FLAG_LOG_QUERY'Save queries   Enable query logging to
                       to             `c:\myodbc.sql'(`/tmp/myodbc.sql')
                       `myodbc.sql'   file. (Enabled only in debug mode.)
1048576 `FLAG_NO_CACHE'Don't Cache    Do not cache the results locally in
                       Result         the driver, instead read from server
                       (forward only  (*Note `mysql_use_result()':
                       cursors)       mysql-use-result.).  This works
                                      only for forward-only cursors. This
                                      option is very important in dealing
                                      with large tables when you don't
                                      want the driver to cache the entire
                                      result set.
2097152 `FLAG_FORWARD_CURSOR'Force Use Of   Force the use of `Forward-only'
                       Forward Only   cursor type. In case of
                       Cursors        applications setting the default
                                      static/dynamic cursor type, and one
                                      wants the driver to use non-cache
                                      result sets, then this option
                                      ensures the forward-only cursor
                                      behavior.
4194304 `FLAG_AUTO_RECONNECT'Enable         Enables auto-reconnection
                       auto-reconnect.functionality. You should not use
                                      this option with transactions,
                                      since a auto reconnection during a
                                      incomplete transaction may cause
                                      corruption. Note that an
                                      auto-reconnected connection will
                                      not inherit the same settings and
                                      environment as the original. This
                                      option was added in Connector/ODBC
                                      3.51.13.
8388608 `FLAG_AUTO_IS_NULL'Flag Auto Is   When set, this option causes the
                       Null           connection to set the
                                      `SQL_AUTO_IS_NULL' option to 1. This
                                      disables the standard behavior, but
                                      may enable older applications to
                                      correctly identify `AUTO_INCREMENT'
                                      values. For more information. See
                                      `IS NULL'. This option was added in
                                      Connector/ODBC 3.51.13.
16777216`FLAG_ZERO_DATE_TO_MIN'Flag Zero      Translates zero dates
                       Date to Min    (`XXXX-00-00') into the minimum
                                      date values supported by ODBC,
                                      `XXXX-01-01'. This resolves an issue
                                      where some statements will not work
                                      because the date returned and the
                                      minimum ODBC date value are
                                      incompatible. This option was added
                                      in Connector/ODBC 3.51.17.
33554432`FLAG_MIN_DATE_TO_ZERO'Flag Min Date  Translates the minimum ODBC date
                       to Zero        value (`XXXX-01-01') to the zero
                                      date format supported by MySQL
                                      (`XXXX-00-00'). This resolves an
                                      issue where some statements will
                                      not work because the date returned
                                      and the minimum ODBC date value are
                                      incompatible. This option was added
                                      in Connector/ODBC 3.51.17.
67108864`FLAG_MULTI_STATEMENTS'Allow          Enables support for batched
                       multiple       statements. This option was added in
                       statements     Connector/ODBC 3.51.18.
134217728`FLAG_COLUMN_SIZE_S32'Limit column   Limits the column size to a signed
                       size to        32-bit value to prevent problems
                       32-bit value   with larger column sizes in
                                      applications that do not support
                                      them. This option is automatically
                                      enabled when working with ADO
                                      applications. This option was added
                                      in Connector/ODBC 3.51.22.
268435456`FLAG_NO_BINARY_RESULT'Always handle  When set this option disables
                       binary         charset 63 for columns with an empty
                       function       `org_table'. This option was added
                       results as     in Connector/ODBC 3.51.26.
                       character data 

To select multiple options, add together their values. For example,
setting `option' to 12 (4+8) gives you debugging without packet limits.

The following table shows some recommended `option' values for various
configurations:

*Configuration*                                               *Option
                                                              Value*
Microsoft Access, Visual Basic                                3
Driver trace generation (Debug mode)                          4
Microsoft Access (with improved DELETE queries)               35
Large tables with too many rows                               2049
Sybase PowerBuilder                                           135168
Query log generation (Debug mode)                             524288
Generate driver trace as well as query log (Debug mode)       524292
Large tables with no-cache results                            3145731


File: manual.info,  Node: myodbc-configuration-dsn-windows,  Next: myodbc-configuration-dsn-macosx,  Prev: myodbc-configuration-connection-parameters,  Up: myodbc-configuration

30.1.4.3 Configuring a Connector/ODBC DSN on Windows
....................................................

* Menu:

* myodbc-configuration-dsn-windows-3-51::  Configuring a Connector/ODBC 3.51 DSN on Windows
* myodbc-configuration-dsn-windows-5-1::  Configuring a Connector/ODBC 5.1 DSN on Windows
* myodbc-configuration-dsn-windows-problems::  Errors and Debugging

The `ODBC Data Source Administrator' within Windows enables you to
create DSNs, check driver installation and configure ODBC systems such
as tracing (used for debugging) and connection pooling.

Different editions and versions of Windows store the `ODBC Data Source
Administrator' in different locations depending on the version of
Windows that you are using.

To open the `ODBC Data Source Administrator' in Windows Server 2003:

*Tip*:

Because it is possible to create DSN using either the 32-bit or 64-bit
driver, but using the same DNS identifier, it is advisable to include
the driver being used within the DSN identifier. This will help you to
identify the DSN when using it from applications such as Excel that are
only compatible with the 32-bit driver. For example, you might add
`Using32bitCODBC' to the DSN identifier for the 32-bit interface and
`Using64bitCODBC' for those using the 64-bit Connector/ODBC driver.

  1. On the `Start' menu, choose `Administrative Tools', and then click
     `Data Sources (ODBC)'.

To open the `ODBC Data Source Administrator' in Windows 2000 Server or
Windows 2000 Professional:

  1. On the `Start' menu, choose `Settings', and then click `Control
     Panel'.

  2. In `Control Panel', click `Administrative Tools'.

  3. In `Administrative Tools', click `Data Sources (ODBC)'.

To open the `ODBC Data Source Administrator' on Windows XP:

  1. On the `Start' menu, click `Control Panel'.

  2. In the `Control Panel' when in `Category View' click `Performance
     and Maintenance' and then click `Administrative Tools.'. If you
     are viewing the `Control Panel' in `Classic View', click
     `Administrative Tools'.

  3. In `Administrative Tools', click `Data Sources (ODBC)'.

Irrespective of your Windows version, you should be presented the `ODBC
Data Source Administrator' window:

`ODBC Data Source Administrator' Dialog

Within Windows XP, you can add the `Administrative Tools' folder to
your `Start' menu to make it easier to locate the ODBC Data Source
Administrator.  To do this:

  1. Right click on the `Start' menu.

  2. Select `Properties'.

  3. Click `Customize...'.

  4. Select the `Advanced' tab.

  5. Within `Start menu items', within the `System Administrative
     Tools' section, select `Display on the All Programs menu'.

Within both Windows Server 2003 and Windows XP you may want to
permanently add the `ODBC Data Source Administrator' to your `Start'
menu. To do this, locate the `Data Sources (ODBC)' icon using the
methods shown, then right-click on the icon and then choose `Pin to
Start Menu'.

The interfaces for the 3.51 and 5.1 versions of the Connector/ODBC
driver are different, although the fields and information that you need
to enter remain the same.

To configure a DSN using Connector/ODBC 3.51.x or Connector/ODBC 5.1.0,
see *Note myodbc-configuration-dsn-windows-3-51::.

To configure a DSN using Connector/ODBC 5.1.1 or later, see *Note
myodbc-configuration-dsn-windows-5-1::.


File: manual.info,  Node: myodbc-configuration-dsn-windows-3-51,  Next: myodbc-configuration-dsn-windows-5-1,  Prev: myodbc-configuration-dsn-windows,  Up: myodbc-configuration-dsn-windows

30.1.4.4 Configuring a Connector/ODBC 3.51 DSN on Windows
.........................................................

To add and configure a new Connector/ODBC data source on Windows, use
the `ODBC Data Source Administrator':

  1. Open the `ODBC Data Source Administrator'.

  2. To create a System DSN (which will be available to all users) ,
     select the `System DSN' tab. To create a User DSN, which will be
     unique only to the current user, click the `Add...' button.

  3. You will need to select the ODBC driver for this DSN.

     `MySQL ODBC Driver Selection' Dialog

     Select `MySQL ODBC 3.51 Driver', then click `Finish'.

  4. You now need to configure the specific fields for the DSN you are
     creating through the `Add Data Source Name' dialog.

     `Add Data Source Name' Dialog for Connector/ODBC 3.51.x

     In the `Data Source Name' box, enter the name of the data source
     you want to access. It can be any valid name that you choose.

  5. In the `Description' box, enter some text to help identify the
     connection.

  6. In the `Server' field, enter the name of the MySQL server host
     that you want to access. By default, it is `localhost'.

  7. In the `User' field, enter the user name to use for this
     connection.

  8. In the `Password' field, enter the corresponding password for this
     connection.

  9. The `Database' pop-up should automatically populate with the list
     of databases that the user has permissions to access.

 10. Click `OK' to save the DSN.

A completed DSN configuration may look like this:

Sample`MySQL ODBC DSN Configuration' Dialog

You can verify the connection using the parameters you have entered by
clicking the `Test' button. If the connection could be made
successfully, you will be notified with a `Success; connection was
made!' dialog.

If the connection failed, you can obtain more information on the test
and why it may have failed by clicking the `Diagnostics...' button to
show additional error messages.

You can configure a number of options for a specific DSN by using
either the `Connect Options' or `Advanced' tabs in the DSN configuration
dialog.

Connector/ODBC Connect Options Dialog

The three options you can configure are:

   * `Port' sets the TCP/IP port number to use when communicating with
     MySQL. Communication with MySQL uses port 3306 by default. If your
     server is configured to use a different TCP/IP port, you must
     specify that port number here.

   * `Socket' sets the name or location of a specific socket or Windows
     pipe to use when communicating with MySQL.

   * `Initial Statement' defines an SQL statement that will be executed
     when the connection to MySQL is opened. You can use this to set
     MySQL options for your connection, such as disabling autocommit.

   * `Character Set' is a pop-up list from which you can select the
     default character set to be used with this connection. The
     Character Set option was added in 3.5.17.

The `Advanced' tab enables you to configure Connector/ODBC connection
parameters. Refer to *Note myodbc-configuration-connection-parameters::,
for information about the meaning of these options.

Connector/ODBC Connection Advanced Dialog


File: manual.info,  Node: myodbc-configuration-dsn-windows-5-1,  Next: myodbc-configuration-dsn-windows-problems,  Prev: myodbc-configuration-dsn-windows-3-51,  Up: myodbc-configuration-dsn-windows

30.1.4.5 Configuring a Connector/ODBC 5.1 DSN on Windows
........................................................

The DSN configuration when using Connector/ODBC 5.1.1 and later has a
slightly different layout. Also, due to the native Unicode support
within Connector/ODBC 5.1, you no longer need to specify the initial
character set to be used with your connection.

To configure a DSN using the Connector/ODBC 5.1.1 or later driver:

  1. Open the `ODBC Data Source Administrator'.

  2. To create a System DSN (which will be available to all users) ,
     select the `System DSN' tab.  To create a User DSN, which will be
     unique only to the current user, click the `Add...' button.

  3. You will need to select the ODBC driver for this DSN.

     `MySQL ODBC Driver Selection' Dialog

     Select `MySQL ODBC 5.1 Driver', then click `Finish'.

  4. You now need to configure the specific fields for the DSN you are
     creating through the `Connection Parameters' dialog.

     `Add Data Source Name' Dialog for Connector/ODBC 5.1

     In the `Data Source Name' box, enter the name of the data source
     you want to access. It can be any valid name that you choose.

  5. In the `Description' box, enter some text to help identify the
     connection.

  6. In the `Server' field, enter the name of the MySQL server host
     that you want to access. By default, it is `localhost'.

  7. In the `User' field, enter the user name to use for this
     connection.

  8. In the `Password' field, enter the corresponding password for this
     connection.

  9. The `Database' pop-up should automatically populate with the list
     of databases that the user has permissions to access.

 10. To communicate over a different TCP/IP port than the default
     (3306), change the value of the `Port'.

 11. Click `OK' to save the DSN.

You can verify the connection using the parameters you have entered by
clicking the `Test' button. If the connection could be made
successfully, you will be notified with a `Success; connection was
made!' dialog.

You can configure a number of options for a specific DSN by using the
`Details' button.

Connector/ODBC Connect Options Dialog

The `Details' button opens a tabbed display which allows you to set
additional options:

   * `Flags 1', `Flags 2', and `Flags 3' enable you to select the
     additional flags for the DSN connection. For more information on
     these flags, see *Note
     myodbc-configuration-connection-parameters::.

   * `Debug' allows you to enable ODBC debugging to record the queries
     you execute through the DSN to the `myodbc.sql' file. For more
     information, see *Note myodbc-configuration-trace::.

   * `SSL Settings' configures the additional options required for
     using the Secure Sockets Layer (SSL) when communicating with MySQL
     server. Note that you must have enabled SSL and configured the
     MySQL server with suitable certificates to communicate over SSL.

     Connector/ODBC 5.1 SSL Configuration

The `Advanced' tab enables you to configure Connector/ODBC connection
parameters. Refer to *Note myodbc-configuration-connection-parameters::,
for information about the meaning of these options.


File: manual.info,  Node: myodbc-configuration-dsn-windows-problems,  Prev: myodbc-configuration-dsn-windows-5-1,  Up: myodbc-configuration-dsn-windows

30.1.4.6 Errors and Debugging
.............................

This section answers Connector/ODBC connection-related questions.

   * *While configuring a Connector/ODBC DSN, a `Could Not Load
     Translator or Setup Library' error occurs*

     For more information, refer to MS KnowledgeBase Article(Q260558)
     (http://support.microsoft.com/default.aspx?scid=kb;EN-US;q260558).
     Also, make sure you have the latest valid `ctl3d32.dll' in your
     system directory.

   * On Windows, the default `myodbc3.dll' is compiled for optimal
     performance. If you want to debug Connector/ODBC 3.51 (for
     example, to enable tracing), you should instead use
     `myodbc3d.dll'. To install this file, copy `myodbc3d.dll' over the
     installed `myodbc3.dll' file.  Make sure to revert back to the
     release version of the driver DLL once you are done with the
     debugging because the debug version may cause performance issues.
     Note that the `myodbc3d.dll' isn't included in Connector/ODBC
     3.51.07 through 3.51.11. If you are using one of these versions,
     you should copy that DLL from a previous version (for example,
     3.51.06).


File: manual.info,  Node: myodbc-configuration-dsn-macosx,  Next: myodbc-configuration-dsn-unix,  Prev: myodbc-configuration-dsn-windows,  Up: myodbc-configuration

30.1.4.7 Configuring a Connector/ODBC DSN on Mac OS X
.....................................................

To configure a DSN on Mac OS X you can either use the `myodbc3i'
utility, edit the `odbc.ini' file within the `Library/ODBC' directory
of the user or the should use the ODBC Administrator. If you have Mac
OS X 10.2 or earlier, refer to *Note myodbc-configuration-dsn-unix::.
Select whether you want to create a User DSN or a System DSN. If you
want to add a System DSN, you may need to authenticate with the system.
You must click the padlock and enter a user and password with
administrator privileges.

For correct operation of ODBC Administrator, you should ensure that the
`/Library/ODBC/odbc.ini' file used to set up ODBC connectivity and DSNs
are writable by the `admin' group. If this file is not writable by this
group then the ODBC Administrator may fail, or may appear to have
worked but not generated the correct entry.

*Warning*:

There are known issues with the OS X ODBC Administrator and
Connector/ODBC that may prevent you from creating a DSN using this
method. In this case you should use the command-line or edit the
`odbc.ini' file directly. Note that existing DSNs or those that you
create via the `myodbc3i' or `myodbc-installer'tool can still be checked
and edited using ODBC Administrator.

To create a DSN using the `myodbc3i' utility, you need only specify the
DSN type and the DSN connection string. For example:

     $ myodbc3i -a -s -t"DSN=mydb;DRIVER=MySQL ODBC 3.51 Driver;SERVER=mysql;USER=username;PASSWORD=pass"

To use ODBC Administrator:

  1. Open the ODBC Administrator from the `Utilities' folder in the
     `Applications' folder.

     `ODBC Administrator Main Panel' Dialog

  2. On the User DSN or System DSN panel, click `Add.'

  3. Select the Connector/ODBC driver and click `OK'.

  4. You will be presented with the `Data Source Name' dialog. Enter
     The `Data Source Name' and an optional `Description' for the DSN.

     `ODBC Administrator Add DSN' Dialog

  5. Click `Add' to add a new keyword/value pair to the panel. You
     should configure at least four pairs to specify the `server',
     `username', `password' and `database' connection parameters. See
     *Note myodbc-configuration-connection-parameters::.

  6. Click `OK' to add the DSN to the list of configured data source
     names.

A completed DSN configuration may look like this:

`ODBC Administrator Sample DSN' Dialog

You can configure additional ODBC options to your DSN by adding further
keyword/value pairs and setting the corresponding values. See *Note
myodbc-configuration-connection-parameters::.


File: manual.info,  Node: myodbc-configuration-dsn-unix,  Next: myodbc-configuration-connection-without-dsn,  Prev: myodbc-configuration-dsn-macosx,  Up: myodbc-configuration

30.1.4.8 Configuring a Connector/ODBC DSN on Unix
.................................................

On `Unix', you configure DSN entries directly in the `odbc.ini' file.
Here is a typical `odbc.ini' file that configures `myodbc3' as the DSN
name for Connector/ODBC 3.51:

     ;
     ;  odbc.ini configuration for Connector/ODBC and Connector/ODBC 3.51 drivers
     ;

     [ODBC Data Sources]
     myodbc3     = MyODBC 3.51 Driver DSN

     [myodbc3]
     Driver       = /usr/local/lib/libmyodbc3.so
     Description  = Connector/ODBC 3.51 Driver DSN
     SERVER       = localhost
     PORT         =
     USER         = root
     Password     =
     Database     = test
     OPTION       = 3
     SOCKET       =

     [Default]
     Driver       = /usr/local/lib/libmyodbc3.so
     Description  = Connector/ODBC 3.51 Driver DSN
     SERVER       = localhost
     PORT         =
     USER         = root
     Password     =
     Database     = test
     OPTION       = 3
     SOCKET       =

Refer to the *Note myodbc-configuration-connection-parameters::, for
the list of connection parameters that can be supplied.

*Note*:

If you are using `unixODBC', you can use the following tools to set up
the DSN:

   * ODBCConfig GUI tool(HOWTO: ODBCConfig
     (http://www.unixodbc.org/config.html))

   * odbcinst

In some cases when using `unixODBC', you might get this error:

     Data source name not found and no default driver specified

If this happens, make sure the `ODBCINI' and `ODBCSYSINI' environment
variables are pointing to the right `odbc.ini' file. For example, if
your `odbc.ini' file is located in `/usr/local/etc', set the environment
variables like this:

     export ODBCINI=/usr/local/etc/odbc.ini
     export ODBCSYSINI=/usr/local/etc


File: manual.info,  Node: myodbc-configuration-connection-without-dsn,  Next: myodbc-configuration-connection-pooling,  Prev: myodbc-configuration-dsn-unix,  Up: myodbc-configuration

30.1.4.9 Connecting Without a Predefined DSN
............................................

You can connect to the MySQL server using SQLDriverConnect, by
specifying the `DRIVER' name field. Here are the connection strings for
Connector/ODBC using DSN-Less connections:

*For Connector/ODBC 3.51:*

     ConnectionString = "DRIVER={MySQL ODBC 3.51 Driver};\
                        SERVER=localhost;\
                        DATABASE=test;\
                        USER=venu;\
                        PASSWORD=venu;\
                        OPTION=3;"

If your programming language converts backslash followed by whitespace
to a space, it is preferable to specify the connection string as a
single long string, or to use a concatenation of multiple strings that
does not add spaces in between. For example:

     ConnectionString = "DRIVER={MySQL ODBC 3.51 Driver};"
                        "SERVER=localhost;"
                        "DATABASE=test;"
                        "USER=venu;"
                        "PASSWORD=venu;"
                        "OPTION=3;"

Note

Note that on Mac OS X you may need to specify the full path to the
Connector/ODBC driver library.

Refer to the *Note myodbc-configuration-connection-parameters::, for
the list of connection parameters that can be supplied.


File: manual.info,  Node: myodbc-configuration-connection-pooling,  Next: myodbc-configuration-trace,  Prev: myodbc-configuration-connection-without-dsn,  Up: myodbc-configuration

30.1.4.10 ODBC Connection Pooling
.................................

Connection pooling enables the ODBC driver to re-use existing
connections to a given database from a pool of connections, instead of
opening a new connection each time the database is accessed. By
enabling connection pooling you can improve the overall performance of
your application by lowering the time taken to open a connection to a
database in the connection pool.

For more information about connection pooling:
`http://support.microsoft.com/default.aspx?scid=kb;EN-US;q169470'.


File: manual.info,  Node: myodbc-configuration-trace,  Prev: myodbc-configuration-connection-pooling,  Up: myodbc-configuration

30.1.4.11 Getting an ODBC Trace File
....................................

* Menu:

* myodbc-configuration-trace-windows::  Enabling ODBC Tracing on Windows
* myodbc-configuration-trace-macosx::  Enabling ODBC Tracing on Mac OS X
* myodbc-configuration-trace-unix::  Enabling ODBC Tracing on Unix
* myodbc-configuration-trace-log::  Enabling a Connector/ODBC Log

If you encounter difficulties or problems with Connector/ODBC, you
should start by making a log file from the `ODBC Manager' and
Connector/ODBC. This is called _tracing_, and is enabled through the
ODBC Manager. The procedure for this differs for Windows, Mac OS X and
Unix.


File: manual.info,  Node: myodbc-configuration-trace-windows,  Next: myodbc-configuration-trace-macosx,  Prev: myodbc-configuration-trace,  Up: myodbc-configuration-trace

30.1.4.12 Enabling ODBC Tracing on Windows
..........................................

To enable the trace option on Windows:

  1. The `Tracing' tab of the ODBC Data Source Administrator dialog box
     enables you to configure the way ODBC function calls are traced.

     ODBC Data Source Administrator Tracing Dialog

  2. When you activate tracing from the `Tracing' tab, the `Driver
     Manager' logs all ODBC function calls for all subsequently run
     applications.

  3. ODBC function calls from applications running before tracing is
     activated are not logged. ODBC function calls are recorded in a
     log file you specify.

  4. Tracing ceases only after you click `Stop Tracing Now'. Remember
     that while tracing is on, the log file continues to increase in
     size and that tracing affects the performance of all your ODBC
     applications.


File: manual.info,  Node: myodbc-configuration-trace-macosx,  Next: myodbc-configuration-trace-unix,  Prev: myodbc-configuration-trace-windows,  Up: myodbc-configuration-trace

30.1.4.13 Enabling ODBC Tracing on Mac OS X
...........................................

To enable the trace option on Mac OS X 10.3 or later you should use the
`Tracing' tab within ODBC Administrator .

  1. Open the ODBC Administrator.

  2. Select the `Tracing' tab.

     ODBC Administrator Tracing Dialog

  3. Select the `Enable Tracing' checkbox.

  4. Enter the location where you want to save the Tracing log.  If you
     want to append information to an existing log file, click the
     `Choose...' button.


File: manual.info,  Node: myodbc-configuration-trace-unix,  Next: myodbc-configuration-trace-log,  Prev: myodbc-configuration-trace-macosx,  Up: myodbc-configuration-trace

30.1.4.14 Enabling ODBC Tracing on Unix
.......................................

To enable the trace option on Mac OS X 10.2 (or earlier) or Unix you
must add the `trace' option to the ODBC configuration:

  1. On Unix, you need to explicitly set the `Trace' option in the
     `ODBC.INI' file.

     Set the tracing `ON' or `OFF' by using `TraceFile' and `Trace'
     parameters in `odbc.ini' as shown below:

          TraceFile  = /tmp/odbc.trace
          Trace      = 1

     `TraceFile' specifies the name and full path of the trace file and
     `Trace' is set to `ON' or `OFF'. You can also use `1' or `YES' for
     `ON' and `0' or `NO' for `OFF'. If you are using `ODBCConfig' from
     `unixODBC', then follow the instructions for tracing `unixODBC'
     calls at HOWTO-ODBCConfig (http://www.unixodbc.org/config.html).


File: manual.info,  Node: myodbc-configuration-trace-log,  Prev: myodbc-configuration-trace-unix,  Up: myodbc-configuration-trace

30.1.4.15 Enabling a Connector/ODBC Log
.......................................

To generate a Connector/ODBC log, do the following:

  1. Within Windows, enable the `Trace Connector/ODBC' option flag in
     the Connector/ODBC connect/configure screen. The log is written to
     file `C:\myodbc.log'. If the trace option is not remembered when
     you are going back to the above screen, it means that you are not
     using the `myodbcd.dll' driver, see *Note
     myodbc-configuration-dsn-windows-problems::.

     On Mac OS X, Unix, or if you are using DSN-Less connection, then
     you need to supply `OPTION=4' in the connection string or set the
     corresponding keyword/value pair in the DSN.

  2. Start your application and try to get it to fail. Then check the
     Connector/ODBC trace file to find out what could be wrong.

If you need help determining what is wrong, see *Note
myodbc-support-community::.


File: manual.info,  Node: myodbc-examples,  Next: myodbc-reference,  Prev: myodbc-configuration,  Up: myodbc-connector

30.1.5 Connector/ODBC Examples
------------------------------

* Menu:

* myodbc-examples-overview::     Basic Connector/ODBC Application Steps
* myodbc-examples-walkthrough::  Step-by-step Guide to Connecting to a MySQL Database through Connector/ODBC
* myodbc-examples-tools::        Connector/ODBC and Third-Party ODBC Tools
* myodbc-examples-tools-with-access::  Using Connector/ODBC with Microsoft Access
* myodbc-examples-tools-with-wordexcel::  Using Connector/ODBC with Microsoft Word or Excel
* myodbc-examples-tools-with-crystalreports::  Using Connector/ODBC with Crystal Reports
* myodbc-examples-programming::  Connector/ODBC Programming

Once you have configured a DSN to provide access to a database, how you
access and use that connection is dependent on the application or
programming language. As ODBC is a standardized interface, any
application or language that supports ODBC can use the DSN and connect
to the configured database.


File: manual.info,  Node: myodbc-examples-overview,  Next: myodbc-examples-walkthrough,  Prev: myodbc-examples,  Up: myodbc-examples

30.1.5.1 Basic Connector/ODBC Application Steps
...............................................

Interacting with a MySQL server from an applications using the
Connector/ODBC typically involves the following operations:

   * Configure the Connector/ODBC DSN

   * Connect to MySQL server

   * Initialization operations

   * Execute SQL statements

   * Retrieve results

   * Perform Transactions

   * Disconnect from the server

Most applications use some variation of these steps. The basic
application steps are shown in the following diagram:

Connector/ODBC Programming Flowchart


File: manual.info,  Node: myodbc-examples-walkthrough,  Next: myodbc-examples-tools,  Prev: myodbc-examples-overview,  Up: myodbc-examples

30.1.5.2 Step-by-step Guide to Connecting to a MySQL Database through Connector/ODBC
....................................................................................

A typical installation situation where you would install Connector/ODBC
is when you want to access a database on a Linux or Unix host from a
Windows machine.

As an example of the process required to set up access between two
machines, the steps below take you through the basic steps.  These
instructions assume that you want to connect to system ALPHA from
system BETA with a username and password of `myuser' and `mypassword'.

On system ALPHA (the MySQL server) follow these steps:

  1. Start the MySQL server.

  2. Use `GRANT' to set up an account with a username of `myuser' that
     can connect from system BETA using a password of `myuser' to the
     database `test':

          GRANT ALL ON test.* to 'myuser'@'BETA' IDENTIFIED BY 'mypassword';

     For more information about MySQL privileges, refer to *Note
     user-account-management::.

On system BETA (the Connector/ODBC client), follow these steps:

  1. Configure a Connector/ODBC DSN using parameters that match the
     server, database and authentication information that you have just
     configured on system ALPHA.

     *Parameter**Value*       *Comment*
     DSN        remote_test   A name to identify the connection.
     SERVER     ALPHA         The address of the remote server.
     DATABASE   test          The name of the default database.
     USER       myuser        The username configured for access to this
                              database.
     PASSWORD   mypassword    The password for `myuser'.

  2. Using an ODBC-capable application, such as Microsoft Office,
     connect to the MySQL server using the DSN you have just created.
     If the connection fails, use tracing to examine the connection
     process. See *Note myodbc-configuration-trace::, for more
     information.


File: manual.info,  Node: myodbc-examples-tools,  Next: myodbc-examples-tools-with-access,  Prev: myodbc-examples-walkthrough,  Up: myodbc-examples

30.1.5.3 Connector/ODBC and Third-Party ODBC Tools
..................................................

Once you have configured your Connector/ODBC DSN, you can access your
MySQL database through any application that supports the ODBC
interface, including programming languages and third-party
applications. This section contains guides and help on using
Connector/ODBC with various ODBC-compatible tools and applications,
including Microsoft Word, Microsoft Excel and Adobe/Macromedia
ColdFusion.

Connector/ODBC has been tested with the following applications:

*Publisher*        *Application*      *Notes*
Adobe              ColdFusion         Formerly Macromedia ColdFusion
Borland            C++ Builder        
                   Builder 4          
                   Delphi             
Business Objects   Crystal Reports    
Claris             Filemaker Pro      
Corel              Paradox            
Computer           Visual Objects     Also known as CAVO
Associates                            
                   AllFusion ERwin    
                   Data Modeler       
Gupta              Team Developer     Previously known as Centura Team
                                      Developer; Gupta SQL/Windows
Gensym             G2-ODBC Bridge     
Inline             iHTML              
Lotus              Notes              Versions 4.5 and 4.6
Microsoft          Access             
                   Excel              
                   Visio Enterprise   
                   Visual C++         
                   Visual Basic       
                   ODBC.NET           Using C#, Visual Basic, C++
                   FoxPro             
                   Visual Interdev    
OpenOffice.org     OpenOffice.org     
Perl               DBD::ODBC          
Pervasive Software DataJunction       
Sambar             Sambar Server      
Technologies                          
SPSS               SPSS               
SoftVelocity       Clarion            
SQLExpress         SQLExpress for     
                   Xbase++            
Sun                StarOffice         
SunSystems         Vision             
Sybase             PowerBuilder       
                   PowerDesigner      
theKompany.com     Data Architect     

If you know of any other applications that work with Connector/ODBC,
please send mail to <myodbc@lists.mysql.com> about them.


File: manual.info,  Node: myodbc-examples-tools-with-access,  Next: myodbc-examples-tools-with-wordexcel,  Prev: myodbc-examples-tools,  Up: myodbc-examples

30.1.5.4 Using Connector/ODBC with Microsoft Access
...................................................

* Menu:

* myodbc-examples-tools-with-access-export::  Exporting Access Data to MySQL
* myodbc-examples-tools-with-access-import::  Importing MySQL Data to Access
* myodbc-examples-tools-with-access-linked-tables::  Using Microsoft Access as a Front-end to MySQL

You can use MySQL database with Microsoft Access using Connector/ODBC.
The MySQL database can be used as an import source, an export source,
or as a linked table for direct use within an Access application, so
you can use Access as the front-end interface to a MySQL database.


File: manual.info,  Node: myodbc-examples-tools-with-access-export,  Next: myodbc-examples-tools-with-access-import,  Prev: myodbc-examples-tools-with-access,  Up: myodbc-examples-tools-with-access

30.1.5.5 Exporting Access Data to MySQL
.......................................

To export a table of data from an Access database to MySQL, follow
these instructions:

  1. When you open an Access database or an Access project, a Database
     window appears. It displays shortcuts for creating new database
     objects and opening existing objects.

     Access Database

  2. Click the name of the `table' or `query' you want to export, and
     then in the `File' menu, select `Export'.

  3. In the `Export Object Type OBJECT NAME To' dialog box, in the
     `Save As Type' box, select `ODBC Databases ()' as shown here:

     Selecting an ODBC Database

  4. In the `Export' dialog box, enter a name for the file (or use the
     suggested name), and then select `OK'.

  5. The Select Data Source dialog box is displayed; it lists the
     defined data sources for any ODBC drivers installed on your
     computer. Click either the File Data Source or Machine Data Source
     tab, and then double-click the Connector/ODBC or Connector/ODBC
     3.51 data source that you want to export to. To define a new data
     source for Connector/ODBC, please *Note
     myodbc-configuration-dsn-windows::.

*Note*:

Ensure that the information that you are exporting to the MySQL table
is valid for the corresponding MySQL data types.  Values that are
outside of the supported range of the MySQL data type but valid within
Access may trigger an `overflow' error during the export.

Microsoft Access connects to the MySQL Server through this data source
and exports new tables and or data.


File: manual.info,  Node: myodbc-examples-tools-with-access-import,  Next: myodbc-examples-tools-with-access-linked-tables,  Prev: myodbc-examples-tools-with-access-export,  Up: myodbc-examples-tools-with-access

30.1.5.6 Importing MySQL Data to Access
.......................................

To import a table or tables from MySQL to Access, follow these
instructions:

  1. Open a database, or switch to the Database window for the open
     database.

  2. To import tables, on the `File' menu, point to `Get External
     Data', and then click `Import'.

  3. In the `Import' dialog box, in the Files Of Type box, select `ODBC
     Databases ()'. The Select Data Source dialog box lists the defined
     data sources `The Select Data Source' dialog box is displayed; it
     lists the defined data source names.

  4. If the ODBC data source that you selected requires you to log on,
     enter your login ID and password (additional information might
     also be required), and then click `OK'.

  5. Microsoft Access connects to the MySQL server through `ODBC data
     source ' and displays the list of tables that you can `import'.

  6. Click each table that you want to `import', and then click `OK'.


File: manual.info,  Node: myodbc-examples-tools-with-access-linked-tables,  Prev: myodbc-examples-tools-with-access-import,  Up: myodbc-examples-tools-with-access

30.1.5.7 Using Microsoft Access as a Front-end to MySQL
.......................................................

You can use Microsoft Access as a front end to a MySQL database by
linking tables within your Microsoft Access database to tables that
exist within your MySQL database. When a query is requested on a table
within Access, ODBC is used to execute the queries on the MySQL
database instead.

*To create a linked table*:

  1. Open the Access database that you want to link to MySQL.

  2. From the `File', choose `Get External Data->Link Tables'.

     Linking Microsoft Access tables to MySQL tables

  3. From the browser, choose `ODBC Databases ()' from the `Files of
     type' pop-up.

  4. In the `Select Data Source' window, choose an existing DSN, either
     from a `File Data Source' or `Machine Data Source'.You can also
     create a new DSN using the `New...' button. For more information
     on creating a DSN see *Note myodbc-configuration-dsn-windows::.

     Linking Microsoft Access tables to MySQL tables, choosing a DSN

  5. In the `Link Tables' dialog, select one or more tables from the
     MySQL database. A link will be created to each table that you
     select from this list.

     Linking Microsoft Access tables to MySQL tables, table selection

  6. If Microsoft Access is unable to determine the unique record
     identifier for a table automatically then it may ask you to
     confirm the column, or combination of columns, to be used to
     uniquely identify each row from the source table. Select the
     columns you want to use and click `OK'.

     Linking Microsoft Access tables to MySQL tables, choosing unique
     record identifier

Once the process has been completed, you can now build interfaces and
queries to the linked tables just as you would for any Access database.

Use the following procedure to view or to refresh links when the
structure or location of a linked table has changed. The Linked Table
Manager lists the paths to all currently linked tables.

*To view or refresh links*:

  1. Open the database that contains links to MySQL tables.

  2. On the `Tools' menu, point to `Add-ins' (`Database Utilities' in
     Access 2000 or newer), and then click `Linked Table Manager'.

  3. Select the check box for the tables whose links you want to
     refresh.

  4. Click OK to refresh the links.

Microsoft Access confirms a successful refresh or, if the table wasn't
found, displays the `Select New Location of' <table name> dialog box in
which you can specify its the table's new location. If several selected
tables have moved to the new location that you specify, the Linked
Table Manager searches that location for all selected tables, and
updates all links in one step.

*To change the path for a set of linked tables*:

  1. Open the database that contains links to tables.

  2. On the `Tools' menu, point to `Add-ins' (`Database Utilities' in
     Access 2000 or newer), and then click `Linked Table Manager'.

  3. Select the `Always Prompt For A New Location' check box.

  4. Select the check box for the tables whose links you want to
     change, and then click `OK'.

  5. In the `Select New Location of' <table name> dialog box, specify
     the new location, click `Open', and then click `OK'.


File: manual.info,  Node: myodbc-examples-tools-with-wordexcel,  Next: myodbc-examples-tools-with-crystalreports,  Prev: myodbc-examples-tools-with-access,  Up: myodbc-examples

30.1.5.8 Using Connector/ODBC with Microsoft Word or Excel
..........................................................

You can use Microsoft Word and Microsoft Excel to access information
from a MySQL database using Connector/ODBC. Within Microsoft Word, this
facility is most useful when importing data for mailmerge, or for
tables and data to be included in reports.  Within Microsoft Excel, you
can execute queries on your MySQL server and import the data directly
into an Excel Worksheet, presenting the data as a series of rows and
columns.

With both applications, data is accessed and imported into the
application using Microsoft Query , which enables you to execute a
query though an ODBC source. You use Microsoft Query to build the SQL
statement to be executed, selecting the tables, fields, selection
criteria and sort order.  For example, to insert information from a
table in the World test database into an Excel spreadsheet, using the
DSN samples shown in *Note myodbc-configuration:::

  1. Create a new Worksheet.

  2. From the `Data' menu, choose `Import External Data', and then
     select `New Database Query'.

  3. Microsoft Query will start.  First, you need to choose the data
     source, by selecting an existing Data Source Name.

     Microsoft Query, Choose Data Source

  4. Within the `Query Wizard', you must choose the columns that you
     want to import. The list of tables available to the user
     configured through the DSN is shown on the left, the columns that
     will be added to your query are shown on the right. The columns
     you choose are equivalent to those in the first section of a
     `SELECT' query. Click `Next' to continue.

     Microsoft Query, Choose Columns

  5. You can filter rows from the query (the equivalent of a `WHERE'
     clause) using the `Filter Data' dialog. Click `Next' to continue.

     Microsoft Query, Filter Data

  6. Select an (optional) sort order for the data. This is equivalent
     to using a `ORDER BY' clause in your SQL query. You can select up
     to three fields for sorting the information returned by the query.
     Click `Next' to continue.

     Microsoft Query, Sort Order

  7. Select the destination for your query. You can select to return
     the data Microsoft Excel, where you can choose a worksheet and
     cell where the data will be inserted; you can continue to view the
     query and results within Microsoft Query, where you can edit the
     SQL query and further filter and sort the information returned; or
     you can create an OLAP Cube from the query, which can then be used
     directly within Microsoft Excel. Click `Finish'.

     Microsoft Query, Selecting a destination

The same process can be used to import data into a Word document, where
the data will be inserted as a table. This can be used for mail merge
purposes (where the field data is read from a Word table), or where you
want to include data and reports within a report or other document.


File: manual.info,  Node: myodbc-examples-tools-with-crystalreports,  Next: myodbc-examples-programming,  Prev: myodbc-examples-tools-with-wordexcel,  Up: myodbc-examples

30.1.5.9 Using Connector/ODBC with Crystal Reports
..................................................

Crystal Reports can use an ODBC DSN to connect to a database from which
you to extract data and information for reporting purposes.

*Note*:

There is a known issue with certain versions of Crystal Reports where
the application is unable to open and browse tables and fields through
an ODBC connection. Before using Crystal Reports with MySQL, please
ensure that you have update to the latest version, including any
outstanding service packs and hotfixes. For more information on this
issue, see the Business) Objects Knowledgebase
(http://support.crystaldecisions.com/library/kbase/new_articles/c2013269.asp)
for more information.

For example, to create a simple crosstab report within Crystal Reports
XI, you should follow these steps:

  1. Create a DSN using the `Data Sources (ODBC)' tool. You can either
     specify a complete database, including username and password, or
     you can build a basic DSN and use Crystal Reports to set the
     username and password.

     For the purposes of this example, a DSN that provides a connection
     to an instance of the MySQL Sakila sample database has been
     created.

  2. Open Crystal Reports and create a new project, or an open an
     existing reporting project into which you want to insert data from
     your MySQL data source.

  3. Start the Cross-Tab Report Wizard, either by clicking on the
     option on the Start Page. Expand the `Create New Connection'
     folder, then expand the `ODBC (RDO)' folder to obtain a list of
     ODBC data sources.

     You will be asked to select a data source.

     Selecting an Data Source in Crystal Reports

  4. When you first expand the `ODBC (RDO)' folder you will be
     presented the Data Source Selection screen. From here you can
     select either a pre-configured DSN, open a file-based DSN or enter
     and manual connection string. For this example, the `Sakila' DSN
     will be used.

     If the DSN contains a username/password combination, or you want
     to use different authentication credentials, click `Next' to enter
     the username and password that you want to use. Otherwise, click
     `Finish' to continue the data source selection wizard.

     Selecting an ODBC Data Source in Crystal Reports

  5. You will be returned the Cross-Tab Report Creation Wizard.  You
     now need to select the database and tables that you want to
     include in your report. For our example, we will expand the
     selected Sakila database. Click the `city' table and use the `>'
     button to add the table to the report. Then repeat the action with
     the `country' table. Alternatively you can select multiple tables
     and add them to the report.

     Finally, you can select the parent `Sakila' resource and add of
     the tables to the report.

     Once you have selected the tables you want to include, click
     `Next' to continue.

     Selecting an tables in Crystal Reports

  6. Crystal Reports will now read the table definitions and
     automatically identify the links between the tables. The
     identification of links between tables enables Crystal Reports to
     automatically lookup and summarize information based on all the
     tables in the database according to your query. If Crystal Reports
     is unable to perform the linking itself, you can manually create
     the links between fields in the tables you have selected.

     Click `Next' to continue the process.

     Table links/structure in Crystal Reports

  7. You can now select the columns and rows that you wish to include
     within the Cross-Tab report. Drag and drop or use the `>' buttons
     to add fields to each area of the report. In the example shown, we
     will report on cities, organized by country, incorporating a count
     of the number of cities within each country. If you want to browse
     the data, select a field and click the `Browse Data...' button.

     Click `Next' to create a graph of the results. Since we are not
     creating a graph from this data, click `Finish' to generate the
     report.

     Cross-tab definition in Crystal Reports

  8. The finished report will be shown, a sample of the output from the
     Sakila sample database is shown below.

     Cross-tab final report in Crystal Reports

Once the ODBC connection has been opened within Crystal Reports, you
can browse and add any fields within the available tables into your
reports.


File: manual.info,  Node: myodbc-examples-programming,  Prev: myodbc-examples-tools-with-crystalreports,  Up: myodbc-examples

30.1.5.10 Connector/ODBC Programming
....................................

* Menu:

* myodbc-examples-programming-vb::  Using Connector/ODBC with Visual Basic Using ADO, DAO and RDO
* myodbc-examples-programming-net::  Using Connector/ODBC with .NET

With a suitable ODBC Manager and the Connector/ODBC driver installed,
any programming language or environment that can support ODBC should be
able to connect to a MySQL database through Connector/ODBC.

This includes, but is certainly not limited to, Microsoft support
languages (including Visual Basic, C# and interfaces such as ODBC.NET),
Perl (through the DBI module, and the DBD::ODBC driver).


File: manual.info,  Node: myodbc-examples-programming-vb,  Next: myodbc-examples-programming-net,  Prev: myodbc-examples-programming,  Up: myodbc-examples-programming

30.1.5.11 Using Connector/ODBC with Visual Basic Using ADO, DAO and RDO
.......................................................................

* Menu:

* myodbc-examples-programming-vb-ado::  ADO: `rs.addNew', `rs.delete', and `rs.update'
* myodbc-examples-programming-vb-dao::  DAO: `rs.addNew', `rs.update', and Scrolling
* myodbc-examples-programming-vb-rdo::  RDO: `rs.addNew' and `rs.update'

This section contains simple examples of the use of MySQL ODBC 3.51
Driver with ADO, DAO and RDO.


File: manual.info,  Node: myodbc-examples-programming-vb-ado,  Next: myodbc-examples-programming-vb-dao,  Prev: myodbc-examples-programming-vb,  Up: myodbc-examples-programming-vb

30.1.5.12 ADO: `rs.addNew', `rs.delete', and `rs.update'
........................................................

The following ADO (ActiveX Data Objects) example creates a table
`my_ado' and demonstrates the use of `rs.addNew', `rs.delete', and
`rs.update'.

     Private Sub myodbc_ado_Click()

     Dim conn As ADODB.Connection
     Dim rs As ADODB.Recordset
     Dim fld As ADODB.Field
     Dim sql As String

     'connect to MySQL server using MySQL ODBC 3.51 Driver
     Set conn = New ADODB.Connection
     conn.ConnectionString = "DRIVER={MySQL ODBC 3.51 Driver};"_
     & "SERVER=localhost;"_
     & " DATABASE=test;"_
     & "UID=venu;PWD=venu; OPTION=3"

     conn.Open

     'create table
     conn.Execute "DROP TABLE IF EXISTS my_ado"
     conn.Execute "CREATE TABLE my_ado(id int not null primary key, name varchar(20)," _
     & "txt text, dt date, tm time, ts timestamp)"

     'direct insert
     conn.Execute "INSERT INTO my_ado(id,name,txt) values(1,100,'venu')"
     conn.Execute "INSERT INTO my_ado(id,name,txt) values(2,200,'MySQL')"
     conn.Execute "INSERT INTO my_ado(id,name,txt) values(3,300,'Delete')"

     Set rs = New ADODB.Recordset
     rs.CursorLocation = adUseServer

     'fetch the initial table ..
     rs.Open "SELECT * FROM my_ado", conn
     Debug.Print rs.RecordCount
     rs.MoveFirst
     Debug.Print String(50, "-") & "Initial my_ado Result Set " & String(50, "-")
     For Each fld In rs.Fields
     Debug.Print fld.Name,
     Next
     Debug.Print

     Do Until rs.EOF
     For Each fld In rs.Fields
     Debug.Print fld.Value,
     Next
     rs.MoveNext
     Debug.Print
     Loop
     rs.Close

     'rs insert
     rs.Open "select * from my_ado", conn, adOpenDynamic, adLockOptimistic
     rs.AddNew
     rs!Name = "Monty"
     rs!txt = "Insert row"
     rs.Update
     rs.Close

     'rs update
     rs.Open "SELECT * FROM my_ado"
     rs!Name = "update"
     rs!txt = "updated-row"
     rs.Update
     rs.Close

     'rs update second time..
     rs.Open "SELECT * FROM my_ado"
     rs!Name = "update"
     rs!txt = "updated-second-time"
     rs.Update
     rs.Close

     'rs delete
     rs.Open "SELECT * FROM my_ado"
     rs.MoveNext
     rs.MoveNext
     rs.Delete
     rs.Close

     'fetch the updated table ..
     rs.Open "SELECT * FROM my_ado", conn
     Debug.Print rs.RecordCount
     rs.MoveFirst
     Debug.Print String(50, "-") & "Updated my_ado Result Set " & String(50, "-")
     For Each fld In rs.Fields
     Debug.Print fld.Name,
     Next
     Debug.Print

     Do Until rs.EOF
     For Each fld In rs.Fields
     Debug.Print fld.Value,
     Next
     rs.MoveNext
     Debug.Print
     Loop
     rs.Close
     conn.Close
     End Sub


File: manual.info,  Node: myodbc-examples-programming-vb-dao,  Next: myodbc-examples-programming-vb-rdo,  Prev: myodbc-examples-programming-vb-ado,  Up: myodbc-examples-programming-vb

30.1.5.13 DAO: `rs.addNew', `rs.update', and Scrolling
......................................................

The following DAO (Data Access Objects) example creates a table
`my_dao' and demonstrates the use of `rs.addNew', `rs.update', and
result set scrolling.

     Private Sub myodbc_dao_Click()

     Dim ws As Workspace
     Dim conn As Connection
     Dim queryDef As queryDef
     Dim str As String

     'connect to MySQL using MySQL ODBC 3.51 Driver
     Set ws = DBEngine.CreateWorkspace("", "venu", "venu", dbUseODBC)
     str = "odbc;DRIVER={MySQL ODBC 3.51 Driver};"_
     & "SERVER=localhost;"_
     & " DATABASE=test;"_
     & "UID=venu;PWD=venu; OPTION=3"
     Set conn = ws.OpenConnection("test", dbDriverNoPrompt, False, str)

     'Create table my_dao
     Set queryDef = conn.CreateQueryDef("", "drop table if exists my_dao")
     queryDef.Execute

     Set queryDef = conn.CreateQueryDef("", "create table my_dao(Id INT AUTO_INCREMENT PRIMARY KEY, " _
     & "Ts TIMESTAMP(14) NOT NULL, Name varchar(20), Id2 INT)")
     queryDef.Execute

     'Insert new records using rs.addNew
     Set rs = conn.OpenRecordset("my_dao")
     Dim i As Integer

     For i = 10 To 15
     rs.AddNew
     rs!Name = "insert record" & i
     rs!Id2 = i
     rs.Update
     Next i
     rs.Close

     'rs update..
     Set rs = conn.OpenRecordset("my_dao")
     rs.Edit
     rs!Name = "updated-string"
     rs.Update
     rs.Close

     'fetch the table back...
     Set rs = conn.OpenRecordset("my_dao", dbOpenDynamic)
     str = "Results:"
     rs.MoveFirst
     While Not rs.EOF
     str = " " & rs!Id & " , " & rs!Name & ", " & rs!Ts & ", " & rs!Id2
     Debug.Print "DATA:" & str
     rs.MoveNext
     Wend

     'rs Scrolling
     rs.MoveFirst
     str = " FIRST ROW: " & rs!Id & " , " & rs!Name & ", " & rs!Ts & ", " & rs!Id2
     Debug.Print str

     rs.MoveLast
     str = " LAST ROW: " & rs!Id & " , " & rs!Name & ", " & rs!Ts & ", " & rs!Id2
     Debug.Print str

     rs.MovePrevious
     str = " LAST-1 ROW: " & rs!Id & " , " & rs!Name & ", " & rs!Ts & ", " & rs!Id2
     Debug.Print str

     'free all resources
     rs.Close
     queryDef.Close
     conn.Close
     ws.Close

     End Sub


File: manual.info,  Node: myodbc-examples-programming-vb-rdo,  Prev: myodbc-examples-programming-vb-dao,  Up: myodbc-examples-programming-vb

30.1.5.14 RDO: `rs.addNew' and `rs.update'
..........................................

The following RDO (Remote Data Objects) example creates a table
`my_rdo' and demonstrates the use of `rs.addNew' and `rs.update'.

     Dim rs As rdoResultset
     Dim cn As New rdoConnection
     Dim cl As rdoColumn
     Dim SQL As String

     'cn.Connect = "DSN=test;"
     cn.Connect = "DRIVER={MySQL ODBC 3.51 Driver};"_
     & "SERVER=localhost;"_
     & " DATABASE=test;"_
     & "UID=venu;PWD=venu; OPTION=3"

     cn.CursorDriver = rdUseOdbc
     cn.EstablishConnection rdDriverPrompt

     'drop table my_rdo
     SQL = "drop table if exists my_rdo"
     cn.Execute SQL, rdExecDirect

     'create table my_rdo
     SQL = "create table my_rdo(id int, name varchar(20))"
     cn.Execute SQL, rdExecDirect

     'insert - direct
     SQL = "insert into my_rdo values (100,'venu')"
     cn.Execute SQL, rdExecDirect

     SQL = "insert into my_rdo values (200,'MySQL')"
     cn.Execute SQL, rdExecDirect

     'rs insert
     SQL = "select * from my_rdo"
     Set rs = cn.OpenResultset(SQL, rdOpenStatic, rdConcurRowVer, rdExecDirect)
     rs.AddNew
     rs!id = 300
     rs!Name = "Insert1"
     rs.Update
     rs.Close

     'rs insert
     SQL = "select * from my_rdo"
     Set rs = cn.OpenResultset(SQL, rdOpenStatic, rdConcurRowVer, rdExecDirect)
     rs.AddNew
     rs!id = 400
     rs!Name = "Insert 2"
     rs.Update
     rs.Close

     'rs update
     SQL = "select * from my_rdo"
     Set rs = cn.OpenResultset(SQL, rdOpenStatic, rdConcurRowVer, rdExecDirect)
     rs.Edit
     rs!id = 999
     rs!Name = "updated"
     rs.Update
     rs.Close

     'fetch back...
     SQL = "select * from my_rdo"
     Set rs = cn.OpenResultset(SQL, rdOpenStatic, rdConcurRowVer, rdExecDirect)
     Do Until rs.EOF
     For Each cl In rs.rdoColumns
     Debug.Print cl.Value,
     Next
     rs.MoveNext
     Debug.Print
     Loop
     Debug.Print "Row count="; rs.RowCount

     'close
     rs.Close
     cn.Close

     End Sub


File: manual.info,  Node: myodbc-examples-programming-net,  Prev: myodbc-examples-programming-vb,  Up: myodbc-examples-programming

30.1.5.15 Using Connector/ODBC with .NET
........................................

* Menu:

* myodbc-examples-programming-net-csharp::  Using Connector/ODBC with ODBC.NET and C# (C sharp)
* myodbc-examples-programming-net-vb::  Using Connector/ODBC with ODBC.NET and Visual Basic

This section contains simple examples that demonstrate the use of
Connector/ODBC drivers with ODBC.NET.


File: manual.info,  Node: myodbc-examples-programming-net-csharp,  Next: myodbc-examples-programming-net-vb,  Prev: myodbc-examples-programming-net,  Up: myodbc-examples-programming-net

30.1.5.16 Using Connector/ODBC with ODBC.NET and C# (C sharp)
.............................................................

The following sample creates a table `my_odbc_net' and demonstrates its
use in C#.

     /**
      * @sample    : mycon.cs
      * @purpose   : Demo sample for ODBC.NET using Connector/ODBC
      * @author    : Venu, <myodbc@lists.mysql.com>
      *
      * (C) Copyright MySQL AB, 1995-2006
      *
      **/

     /* build command
      *
      *  csc /t:exe
      *      /out:mycon.exe mycon.cs
      *      /r:Microsoft.Data.Odbc.dll
      */

     using Console = System.Console;
     using Microsoft.Data.Odbc;

     namespace myodbc3
     {
       class mycon
       {
         static void Main(string[] args)
         {
           try
             {
               //Connection string for Connector/ODBC 3.51
               string MyConString = "DRIVER={MySQL ODBC 3.51 Driver};" +
                 "SERVER=localhost;" +
                 "DATABASE=test;" +
                 "UID=venu;" +
                 "PASSWORD=venu;" +
                 "OPTION=3";

               //Connect to MySQL using Connector/ODBC
               OdbcConnection MyConnection = new OdbcConnection(MyConString);
               MyConnection.Open();

               Console.WriteLine("\n !!! success, connected successfully !!!\n");

               //Display connection information
               Console.WriteLine("Connection Information:");
               Console.WriteLine("\tConnection String:" +
                                 MyConnection.ConnectionString);
               Console.WriteLine("\tConnection Timeout:" +
                                 MyConnection.ConnectionTimeout);
               Console.WriteLine("\tDatabase:" +
                                 MyConnection.Database);
               Console.WriteLine("\tDataSource:" +
                                 MyConnection.DataSource);
               Console.WriteLine("\tDriver:" +
                                 MyConnection.Driver);
               Console.WriteLine("\tServerVersion:" +
                                 MyConnection.ServerVersion);

               //Create a sample table
               OdbcCommand MyCommand =
                 new OdbcCommand("DROP TABLE IF EXISTS my_odbc_net",
                                 MyConnection);
               MyCommand.ExecuteNonQuery();
               MyCommand.CommandText =
                 "CREATE TABLE my_odbc_net(id int, name varchar(20), idb bigint)";
               MyCommand.ExecuteNonQuery();

               //Insert
               MyCommand.CommandText =
                 "INSERT INTO my_odbc_net VALUES(10,'venu', 300)";
               Console.WriteLine("INSERT, Total rows affected:" +
                                 MyCommand.ExecuteNonQuery());;

               //Insert
               MyCommand.CommandText =
                 "INSERT INTO my_odbc_net VALUES(20,'mysql',400)";
               Console.WriteLine("INSERT, Total rows affected:" +
                                 MyCommand.ExecuteNonQuery());

               //Insert
               MyCommand.CommandText =
                 "INSERT INTO my_odbc_net VALUES(20,'mysql',500)";
               Console.WriteLine("INSERT, Total rows affected:" +
                                 MyCommand.ExecuteNonQuery());

               //Update
               MyCommand.CommandText =
                 "UPDATE my_odbc_net SET id=999 WHERE id=20";
               Console.WriteLine("Update, Total rows affected:" +
                                 MyCommand.ExecuteNonQuery());

               //COUNT(*)
               MyCommand.CommandText =
                 "SELECT COUNT(*) as TRows FROM my_odbc_net";
               Console.WriteLine("Total Rows:" +
                                 MyCommand.ExecuteScalar());

               //Fetch
               MyCommand.CommandText = "SELECT * FROM my_odbc_net";
               OdbcDataReader MyDataReader;
               MyDataReader =  MyCommand.ExecuteReader();
               while (MyDataReader.Read())
                 {
                   if(string.Compare(MyConnection.Driver,"myodbc3.dll") == 0) {
                     //Supported only by Connector/ODBC 3.51
                     Console.WriteLine("Data:" + MyDataReader.GetInt32(0) + " " +
                                       MyDataReader.GetString(1) + " " +
                                       MyDataReader.GetInt64(2));
                   }
                   else {
                     //BIGINTs not supported by Connector/ODBC
                     Console.WriteLine("Data:" + MyDataReader.GetInt32(0) + " " +
                                       MyDataReader.GetString(1) + " " +
                                       MyDataReader.GetInt32(2));
                   }
                 }

               //Close all resources
               MyDataReader.Close();
               MyConnection.Close();
             }
           catch (OdbcException MyOdbcException) //Catch any ODBC exception ..
             {
               for (int i=0; i < MyOdbcException.Errors.Count; i++)
                 {
                   Console.Write("ERROR #" + i + "\n" +
                                 "Message: " +
                                 MyOdbcException.Errors[i].Message + "\n" +
                                 "Native: " +
                                 MyOdbcException.Errors[i].NativeError.ToString() + "\n" +
                                 "Source: " +
                                 MyOdbcException.Errors[i].Source + "\n" +
                                 "SQL: " +
                                 MyOdbcException.Errors[i].SQLState + "\n");
                 }
             }
         }
       }
     }


File: manual.info,  Node: myodbc-examples-programming-net-vb,  Prev: myodbc-examples-programming-net-csharp,  Up: myodbc-examples-programming-net

30.1.5.17 Using Connector/ODBC with ODBC.NET and Visual Basic
.............................................................

The following sample creates a table `my_vb_net' and demonstrates the
use in VB.

     ' @sample    : myvb.vb
     ' @purpose   : Demo sample for ODBC.NET using Connector/ODBC
     ' @author    : Venu, <myodbc@lists.mysql.com>
     '
     ' (C) Copyright MySQL AB, 1995-2006
     '
     '

     '
     ' build command
     '
     ' vbc /target:exe
     '     /out:myvb.exe
     '     /r:Microsoft.Data.Odbc.dll
     '     /r:System.dll
     '     /r:System.Data.dll
     '

     Imports Microsoft.Data.Odbc
     Imports System

     Module myvb
       Sub Main()
         Try

           'Connector/ODBC 3.51 connection string
           Dim MyConString As String = "DRIVER={MySQL ODBC 3.51 Driver};" & _
           "SERVER=localhost;" & _
           "DATABASE=test;" & _
           "UID=venu;" & _
           "PASSWORD=venu;" & _
           "OPTION=3;"

           'Connection
           Dim MyConnection As New OdbcConnection(MyConString)
           MyConnection.Open()

           Console.WriteLine("Connection State::" & MyConnection.State.ToString)

           'Drop
           Console.WriteLine("Dropping table")
           Dim MyCommand As New OdbcCommand()
           MyCommand.Connection = MyConnection
           MyCommand.CommandText = "DROP TABLE IF EXISTS my_vb_net"
           MyCommand.ExecuteNonQuery()

           'Create
           Console.WriteLine("Creating....")
           MyCommand.CommandText = "CREATE TABLE my_vb_net(id int, name varchar(30))"
           MyCommand.ExecuteNonQuery()

           'Insert
           MyCommand.CommandText = "INSERT INTO my_vb_net VALUES(10,'venu')"
           Console.WriteLine("INSERT, Total rows affected:" & _
           MyCommand.ExecuteNonQuery())

           'Insert
           MyCommand.CommandText = "INSERT INTO my_vb_net VALUES(20,'mysql')"
           Console.WriteLine("INSERT, Total rows affected:" & _
           MyCommand.ExecuteNonQuery())

           'Insert
           MyCommand.CommandText = "INSERT INTO my_vb_net VALUES(20,'mysql')"
           Console.WriteLine("INSERT, Total rows affected:" & _
           MyCommand.ExecuteNonQuery())

           'Insert
           MyCommand.CommandText = "INSERT INTO my_vb_net(id) VALUES(30)"
           Console.WriteLine("INSERT, Total rows affected:" & _
                             MyCommand.ExecuteNonQuery())

           'Update
           MyCommand.CommandText = "UPDATE my_vb_net SET id=999 WHERE id=20"
           Console.WriteLine("Update, Total rows affected:" & _
           MyCommand.ExecuteNonQuery())

           'COUNT(*)
           MyCommand.CommandText = "SELECT COUNT(*) as TRows FROM my_vb_net"
           Console.WriteLine("Total Rows:" & MyCommand.ExecuteScalar())

           'Select
           Console.WriteLine("Select * FROM my_vb_net")
           MyCommand.CommandText = "SELECT * FROM my_vb_net"
           Dim MyDataReader As OdbcDataReader
           MyDataReader = MyCommand.ExecuteReader
           While MyDataReader.Read
             If MyDataReader("name") Is DBNull.Value Then
               Console.WriteLine("id = " & _
               CStr(MyDataReader("id")) & "  name = " & _
               "NULL")
             Else
               Console.WriteLine("id = " & _
               CStr(MyDataReader("id")) & "  name = " & _
               CStr(MyDataReader("name")))
             End If
           End While

           'Catch ODBC Exception
         Catch MyOdbcException As OdbcException
           Dim i As Integer
           Console.WriteLine(MyOdbcException.ToString)

           'Catch program exception
         Catch MyException As Exception
           Console.WriteLine(MyException.ToString)
         End Try
       End Sub


File: manual.info,  Node: myodbc-reference,  Next: myodbc-usagenotes,  Prev: myodbc-examples,  Up: myodbc-connector

30.1.6 Connector/ODBC Reference
-------------------------------

* Menu:

* myodbc-reference-api::         Connector/ODBC API Reference
* myodbc-reference-datatypes::   Connector/ODBC Data Types
* myodbc-reference-errorcodes::  Connector/ODBC Error Codes

This section provides reference material for the Connector/ODBC API,
showing supported functions and methods, supported MySQL column types
and the corresponding native type in Connector/ODBC, and the error
codes returned by Connector/ODBC when a fault occurs.


File: manual.info,  Node: myodbc-reference-api,  Next: myodbc-reference-datatypes,  Prev: myodbc-reference,  Up: myodbc-reference

30.1.6.1 Connector/ODBC API Reference
.....................................

This section summarizes ODBC routines, categorized by functionality.

For the complete ODBC API reference, please refer to the ODBC
Programmer's Reference at
`http://msdn.microsoft.com/en-us/library/ms714177.aspx'.

An application can call `SQLGetInfo' function to obtain conformance
information about Connector/ODBC. To obtain information about support
for a specific function in the driver, an application can call
`SQLGetFunctions'.

*Note*:

For backward compatibility, the Connector/ODBC 3.51 driver supports all
deprecated functions.

The following tables list Connector/ODBC API calls grouped by task:

*Connecting to a data source:*

*Function name*     *C/ODBC   *Standard**Purpose*
                    3.51*               
`SQLAllocHandle'    Yes       ISO 92    Obtains an environment, connection,
                                        statement, or descriptor handle.
`SQLConnect'        Yes       ISO 92    Connects to a specific driver by
                                        data source name, user ID, and
                                        password.
`SQLDriverConnect'  Yes       ODBC      Connects to a specific driver by
                                        connection string or requests that
                                        the Driver Manager and driver
                                        display connection dialog boxes for
                                        the user.
`SQLAllocEnv'       Yes       DeprecatedObtains an environment handle
                                        allocated from driver.
`SQLAllocConnect'   Yes       DeprecatedObtains a connection handle

*Obtaining information about a driver and data source:*

*Function name*     *C/ODBC   *Standard**Purpose*
                    3.51*               
`SQLDataSources'    No        ISO 92    Returns the list of available data
                                        sources, handled by the Driver
                                        Manager
`SQLDrivers'        No        ODBC      Returns the list of installed
                                        drivers and their attributes,
                                        handles by Driver Manager
`SQLGetInfo'        Yes       ISO 92    Returns information about a
                                        specific driver and data source.
`SQLGetFunctions'   Yes       ISO 92    Returns supported driver functions.
`SQLGetTypeInfo'    Yes       ISO 92    Returns information about supported
                                        data types.

*Setting and retrieving driver attributes:*

*Function name*     *C/ODBC   *Standard**Purpose*
                    3.51*               
`SQLSetConnectAttr' Yes       ISO 92    Sets a connection attribute.
`SQLGetConnectAttr' Yes       ISO 92    Returns the value of a connection
                                        attribute.
`SQLSetConnectOption'Yes       DeprecatedSets a connection option
`SQLGetConnectOption'Yes       DeprecatedReturns the value of a connection
                                        option
`SQLSetEnvAttr'     Yes       ISO 92    Sets an environment attribute.
`SQLGetEnvAttr'     Yes       ISO 92    Returns the value of an environment
                                        attribute.
`SQLSetStmtAttr'    Yes       ISO 92    Sets a statement attribute.
`SQLGetStmtAttr'    Yes       ISO 92    Returns the value of a statement
                                        attribute.
`SQLSetStmtOption'  Yes       DeprecatedSets a statement option
`SQLGetStmtOption'  Yes       DeprecatedReturns the value of a statement
                                        option

*Preparing SQL requests:*

*Function name*     *C/ODBC   *Standard**Purpose*
                    3.51*               
`SQLAllocStmt'      Yes       DeprecatedAllocates a statement handle
`SQLPrepare'        Yes       ISO 92    Prepares an SQL statement for later
                                        execution.
`SQLBindParameter'  Yes       ODBC      Assigns storage for a parameter in
                                        an SQL statement.
`SQLGetCursorName'  Yes       ISO 92    Returns the cursor name associated
                                        with a statement handle.
`SQLSetCursorName'  Yes       ISO 92    Specifies a cursor name.
`SQLSetScrollOptions'Yes       ODBC      Sets options that control cursor
                                        behavior.

*Submitting requests:*

*Function name*     *C/ODBC   *Standard**Purpose*
                    3.51*               
`SQLExecute'        Yes       ISO 92    Executes a prepared statement.
`SQLExecDirect'     Yes       ISO 92    Executes a statement
`SQLNativeSql'      Yes       ODBC      Returns the text of an SQL
                                        statement as translated by the
                                        driver.
`SQLDescribeParam'  Yes       ODBC      Returns the description for a
                                        specific parameter in a statement.
`SQLNumParams'      Yes       ISO 92    Returns the number of parameters in
                                        a statement.
`SQLParamData'      Yes       ISO 92    Used in conjunction with
                                        `SQLPutData' to supply parameter
                                        data at execution time. (Useful for
                                        long data values.)
`SQLPutData'        Yes       ISO 92    Sends part or all of a data value
                                        for a parameter. (Useful for long
                                        data values.)

*Retrieving results and information about results:*

*Function name*     *C/ODBC   *Standard**Purpose*
                    3.51*               
`SQLRowCount'       Yes       ISO 92    Returns the number of rows affected
                                        by an insert, update, or delete
                                        request.
`SQLNumResultCols'  Yes       ISO 92    Returns the number of columns in
                                        the result set.
`SQLDescribeCol'    Yes       ISO 92    Describes a column in the result
                                        set.
`SQLColAttribute'   Yes       ISO 92    Describes attributes of a column in
                                        the result set.
`SQLColAttributes'  Yes       DeprecatedDescribes attributes of a column in
                                        the result set.
`SQLFetch'          Yes       ISO 92    Returns multiple result rows.
`SQLFetchScroll'    Yes       ISO 92    Returns scrollable result rows.
`SQLExtendedFetch'  Yes       DeprecatedReturns scrollable result rows.
`SQLSetPos'         Yes       ODBC      Positions a cursor within a fetched
                                        block of data and allows an
                                        application to refresh data in the
                                        rowset or to update or delete data
                                        in the result set.
`SQLBulkOperations' Yes       ODBC      Performs bulk insertions and bulk
                                        bookmark operations, including
                                        update, delete, and fetch by
                                        bookmark.

*Retrieving error or diagnostic information:*

*Function name*     *C/ODBC   *Standard**Purpose*
                    3.51*               
`SQLError'          Yes       DeprecatedReturns additional error or status
                                        information
`SQLGetDiagField'   Yes       ISO 92    Returns additional diagnostic
                                        information (a single field of the
                                        diagnostic data structure).
`SQLGetDiagRec'     Yes       ISO 92    Returns additional diagnostic
                                        information (multiple fields of the
                                        diagnostic data structure).

*Obtaining information about the data source's system tables (catalog
functions) item:*

*Function name*     *C/ODBC   *Standard**Purpose*
                    3.51*               
`SQLColumnPrivileges'Yes       ODBC      Returns a list of columns and
                                        associated privileges for one or
                                        more tables.
`SQLColumns'        Yes       X/Open    Returns the list of column names in
                                        specified tables.
`SQLForeignKeys'    Yes       ODBC      Returns a list of column names that
                                        make up foreign keys, if they exist
                                        for a specified table.
`SQLPrimaryKeys'    Yes       ODBC      Returns the list of column names
                                        that make up the primary key for a
                                        table.
`SQLSpecialColumns' Yes       X/Open    Returns information about the
                                        optimal set of columns that uniquely
                                        identifies a row in a specified
                                        table, or the columns that are
                                        automatically updated when any
                                        value in the row is updated by a
                                        transaction.
`SQLStatistics'     Yes       ISO 92    Returns statistics about a single
                                        table and the list of indexes
                                        associated with the table.
`SQLTablePrivileges'Yes       ODBC      Returns a list of tables and the
                                        privileges associated with each
                                        table.
`SQLTables'         Yes       X/Open    Returns the list of table names
                                        stored in a specific data source.

*Performing transactions:*

*Function name*     *C/ODBC   *Standard**Purpose*
                    3.51*               
`SQLTransact'       Yes       DeprecatedCommits or rolls back a transaction
`SQLEndTran'        Yes       ISO 92    Commits or rolls back a transaction.

*Terminating a statement:*

*Function name*     *C/ODBC   *Standard**Purpose*
                    3.51*               
`SQLFreeStmt'       Yes       ISO 92    Ends statement processing, discards
                                        pending results, and, optionally,
                                        frees all resources associated with
                                        the statement handle.
`SQLCloseCursor'    Yes       ISO 92    Closes a cursor that has been
                                        opened on a statement handle.
`SQLCancel'         Yes       ISO 92    Cancels an SQL statement.

*Terminating a connection:*

*Function name*     *C/ODBC   *Standard**Purpose*
                    3.51*               
`SQLDisconnect'     Yes       ISO 92    Closes the connection.
`SQLFreeHandle'     Yes       ISO 92    Releases an environment,
                                        connection, statement, or
                                        descriptor handle.
`SQLFreeConnect'    Yes       DeprecatedReleases connection handle
`SQLFreeEnv'        Yes       DeprecatedReleases an environment handle


File: manual.info,  Node: myodbc-reference-datatypes,  Next: myodbc-reference-errorcodes,  Prev: myodbc-reference-api,  Up: myodbc-reference

30.1.6.2 Connector/ODBC Data Types
..................................

The following table illustrates how driver maps the server data types
to default SQL and C data types:

*Native Value*           *SQL Type*               *C Type*
`bigint unsigned'        `SQL_BIGINT'             `SQL_C_UBIGINT'
`bigint'                 `SQL_BIGINT'             `SQL_C_SBIGINT'
`bit'                    `SQL_BIT'                `SQL_C_BIT'
`bit'                    `SQL_CHAR'               `SQL_C_CHAR'
`blob'                   `SQL_LONGVARBINARY'      `SQL_C_BINARY'
`bool'                   `SQL_CHAR'               `SQL_C_CHAR'
`char'                   `SQL_CHAR'               `SQL_C_CHAR'
`date'                   `SQL_DATE'               `SQL_C_DATE'
`datetime'               `SQL_TIMESTAMP'          `SQL_C_TIMESTAMP'
`decimal'                `SQL_DECIMAL'            `SQL_C_CHAR'
`double precision'       `SQL_DOUBLE'             `SQL_C_DOUBLE'
`double'                 `SQL_FLOAT'              `SQL_C_DOUBLE'
`enum'                   `SQL_VARCHAR'            `SQL_C_CHAR'
`float'                  `SQL_REAL'               `SQL_C_FLOAT'
`int unsigned'           `SQL_INTEGER'            `SQL_C_ULONG'
`int'                    `SQL_INTEGER'            `SQL_C_SLONG'
`integer unsigned'       `SQL_INTEGER'            `SQL_C_ULONG'
`integer'                `SQL_INTEGER'            `SQL_C_SLONG'
`long varbinary'         `SQL_LONGVARBINARY'      `SQL_C_BINARY'
`long varchar'           `SQL_LONGVARCHAR'        `SQL_C_CHAR'
`longblob'               `SQL_LONGVARBINARY'      `SQL_C_BINARY'
`longtext'               `SQL_LONGVARCHAR'        `SQL_C_CHAR'
`mediumblob'             `SQL_LONGVARBINARY'      `SQL_C_BINARY'
`mediumint unsigned'     `SQL_INTEGER'            `SQL_C_ULONG'
`mediumint'              `SQL_INTEGER'            `SQL_C_SLONG'
`mediumtext'             `SQL_LONGVARCHAR'        `SQL_C_CHAR'
`numeric'                `SQL_NUMERIC'            `SQL_C_CHAR'
`real'                   `SQL_FLOAT'              `SQL_C_DOUBLE'
`set'                    `SQL_VARCHAR'            `SQL_C_CHAR'
`smallint unsigned'      `SQL_SMALLINT'           `SQL_C_USHORT'
`smallint'               `SQL_SMALLINT'           `SQL_C_SSHORT'
`text'                   `SQL_LONGVARCHAR'        `SQL_C_CHAR'
`time'                   `SQL_TIME'               `SQL_C_TIME'
`timestamp'              `SQL_TIMESTAMP'          `SQL_C_TIMESTAMP'
`tinyblob'               `SQL_LONGVARBINARY'      `SQL_C_BINARY'
`tinyint unsigned'       `SQL_TINYINT'            `SQL_C_UTINYINT'
`tinyint'                `SQL_TINYINT'            `SQL_C_STINYINT'
`tinytext'               `SQL_LONGVARCHAR'        `SQL_C_CHAR'
`varchar'                `SQL_VARCHAR'            `SQL_C_CHAR'
`year'                   `SQL_SMALLINT'           `SQL_C_SHORT'


File: manual.info,  Node: myodbc-reference-errorcodes,  Prev: myodbc-reference-datatypes,  Up: myodbc-reference

30.1.6.3 Connector/ODBC Error Codes
...................................

The following tables lists the error codes returned by the driver apart
from the server errors.

*Native *SQLSTATE 2* *SQLSTATE 3* *Error Message*
Code*                             
500     01000        01000        General warning
501     01004        01004        String data, right truncated
502     01S02        01S02        Option value changed
503     01S03        01S03        No rows updated/deleted
504     01S04        01S04        More than one row updated/deleted
505     01S06        01S06        Attempt to fetch before the result set
                                  returned the first row set
506     07001        07002        `SQLBindParameter' not used for all
                                  parameters
507     07005        07005        Prepared statement not a
                                  cursor-specification
508     07009        07009        Invalid descriptor index
509     08002        08002        Connection name in use
510     08003        08003        Connection does not exist
511     24000        24000        Invalid cursor state
512     25000        25000        Invalid transaction state
513     25S01        25S01        Transaction state unknown
514     34000        34000        Invalid cursor name
515     S1000        HY000        General driver defined error
516     S1001        HY001        Memory allocation error
517     S1002        HY002        Invalid column number
518     S1003        HY003        Invalid application buffer type
519     S1004        HY004        Invalid SQL data type
520     S1009        HY009        Invalid use of null pointer
521     S1010        HY010        Function sequence error
522     S1011        HY011        Attribute can not be set now
523     S1012        HY012        Invalid transaction operation code
524     S1013        HY013        Memory management error
525     S1015        HY015        No cursor name available
526     S1024        HY024        Invalid attribute value
527     S1090        HY090        Invalid string or buffer length
528     S1091        HY091        Invalid descriptor field identifier
529     S1092        HY092        Invalid attribute/option identifier
530     S1093        HY093        Invalid parameter number
531     S1095        HY095        Function type out of range
532     S1106        HY106        Fetch type out of range
533     S1117        HY117        Row value out of range
534     S1109        HY109        Invalid cursor position
535     S1C00        HYC00        Optional feature not implemented
0       21S01        21S01        Column count does not match value count
0       23000        23000        Integrity constraint violation
0       42000        42000        Syntax error or access violation
0       42S02        42S02        Base table or view not found
0       42S12        42S12        Index not found
0       42S21        42S21        Column already exists
0       42S22        42S22        Column not found
0       08S01        08S01        Communication link failure


File: manual.info,  Node: myodbc-usagenotes,  Next: myodbc-support,  Prev: myodbc-reference,  Up: myodbc-connector

30.1.7 Connector/ODBC Notes and Tips
------------------------------------

* Menu:

* myodbc-usagenotes-functionality::  Connector/ODBC General Functionality
* myodbc-usagenotes-apptips::    Connector/ODBC Application Specific Tips
* myodbc-errors::                Connector/ODBC Errors and Resolutions (FAQ)

Here are some common notes and tips for using Connector/ODBC within
different environments, applications and tools. The notes provided here
are based on the experiences of Connector/ODBC developers and users.


File: manual.info,  Node: myodbc-usagenotes-functionality,  Next: myodbc-usagenotes-apptips,  Prev: myodbc-usagenotes,  Up: myodbc-usagenotes

30.1.7.1 Connector/ODBC General Functionality
.............................................

* Menu:

* myodbc-usagenotes-functionality-last-insert-id::  Obtaining Auto-Increment Values
* myodbc-usagenotes-functionality-dynamic-cursor::  Dynamic Cursor Support
* myodbc-usagenotes-functionality-performance::  Connector/ODBC Performance
* myodbc-usagenotes-functionality-query-timeout::  Setting ODBC Query Timeout in Windows

This section provides help with common queries and areas of
functionality in MySQL and how to use them with Connector/ODBC.


File: manual.info,  Node: myodbc-usagenotes-functionality-last-insert-id,  Next: myodbc-usagenotes-functionality-dynamic-cursor,  Prev: myodbc-usagenotes-functionality,  Up: myodbc-usagenotes-functionality

30.1.7.2 Obtaining Auto-Increment Values
........................................

Obtaining the value of column that uses `AUTO_INCREMENT' after an
`INSERT' statement can be achieved in a number of different ways. To
obtain the value immediately after an `INSERT', use a `SELECT' query
with the `LAST_INSERT_ID()' function.

For example, using Connector/ODBC you would execute two separate
statements, the `INSERT' statement and the `SELECT' query to obtain the
auto-increment value.

     INSERT INTO tbl (auto,text) VALUES(NULL,'text');
     SELECT LAST_INSERT_ID();

If you do not require the value within your application, but do require
the value as part of another `INSERT', the entire process can be handled
by executing the following statements:

     INSERT INTO tbl (auto,text) VALUES(NULL,'text');
     INSERT INTO tbl2 (id,text) VALUES(LAST_INSERT_ID(),'text');

Certain ODBC applications (including Delphi and Access) may have
trouble obtaining the auto-increment value using the previous examples.
In this case, try the following statement as an alternative:

     SELECT * FROM tbl WHERE auto IS NULL;

See *Note getting-unique-id::.


File: manual.info,  Node: myodbc-usagenotes-functionality-dynamic-cursor,  Next: myodbc-usagenotes-functionality-performance,  Prev: myodbc-usagenotes-functionality-last-insert-id,  Up: myodbc-usagenotes-functionality

30.1.7.3 Dynamic Cursor Support
...............................

Support for the `dynamic cursor' is provided in Connector/ODBC 3.51,
but dynamic cursors are not enabled by default. You can enable this
function within Windows by selecting the `Enable Dynamic Cursor'
checkbox within the ODBC Data Source Administrator.

On other platforms, you can enable the dynamic cursor by adding `32' to
the `OPTION' value when creating the DSN.


File: manual.info,  Node: myodbc-usagenotes-functionality-performance,  Next: myodbc-usagenotes-functionality-query-timeout,  Prev: myodbc-usagenotes-functionality-dynamic-cursor,  Up: myodbc-usagenotes-functionality

30.1.7.4 Connector/ODBC Performance
...................................

The Connector/ODBC driver has been optimized to provide very fast
performance. If you experience problems with the performance of
Connector/ODBC, or notice a large amount of disk activity for simple
queries, there are a number of aspects you should check:

   * Ensure that `ODBC Tracing' is not enabled. With tracing enabled, a
     lot of information is recorded in the tracing file by the ODBC
     Manager. You can check, and disable, tracing within Windows using
     the `Tracing' panel of the ODBC Data Source Administrator. Within
     Mac OS X, check the `Tracing' panel of ODBC Administrator. See
     *Note myodbc-configuration-trace::.

   * Make sure you are using the standard version of the driver, and
     not the debug version. The debug version includes additional
     checks and reporting measures.

   * Disable the Connector/ODBC driver trace and query logs.  These
     options are enabled for each DSN, so make sure to examine only the
     DSN that you are using in your application. Within Windows, you
     can disable the Connector/ODBC and query logs by modifying the DSN
     configuration. Within Mac OS X and Unix, ensure that the driver
     trace (option value 4) and query logging (option value 524288) are
     not enabled.


File: manual.info,  Node: myodbc-usagenotes-functionality-query-timeout,  Prev: myodbc-usagenotes-functionality-performance,  Up: myodbc-usagenotes-functionality

30.1.7.5 Setting ODBC Query Timeout in Windows
..............................................

For more information on how to set the query timeout on Microsoft
Windows when executing queries through an ODBC connection, read the
Microsoft knowledgebase document at
`http://support.microsoft.com/default.aspx?scid=kb%3Ben-us%3B153756'.


File: manual.info,  Node: myodbc-usagenotes-apptips,  Next: myodbc-errors,  Prev: myodbc-usagenotes-functionality,  Up: myodbc-usagenotes

30.1.7.6 Connector/ODBC Application Specific Tips
.................................................

* Menu:

* myodbc-usagenotes-apptips-microsoft::  Using Connector/ODBC with Microsoft Applications
* myodbc-usagenotes-apptips-borland::  Using Connector/ODBC with Borland Applications
* myodbc-usagenotes-apptips-coldfusion::  Using Connector/ODBC with ColdFusion
* myodbc-usagenotes-apptips-openoffice::  Using Connector/ODBC with OpenOffice.org
* myodbc-usagenotes-apptips-sambarserver::  Using Connector/ODBC with Sambar Server
* myodbc-usagenotes-apptips-datajunction::  Using Connector/ODBC with Pervasive Software DataJunction
* myodbc-usagenotes-apptips-vision::  Using Connector/ODBC with SunSystems Vision

Most programs should work with Connector/ODBC, but for each of those
listed here, there are specific notes and tips to improve or enhance
the way you work with Connector/ODBC and these applications.

With all applications you should ensure that you are using the latest
Connector/ODBC drivers, ODBC Manager and any supporting libraries and
interfaces used by your application. For example, on Windows, using the
latest version of Microsoft Data Access Components (MDAC) will improve
the compatibility with ODBC in general, and with the Connector/ODBC
driver.


File: manual.info,  Node: myodbc-usagenotes-apptips-microsoft,  Next: myodbc-usagenotes-apptips-borland,  Prev: myodbc-usagenotes-apptips,  Up: myodbc-usagenotes-apptips

30.1.7.7 Using Connector/ODBC with Microsoft Applications
.........................................................

* Menu:

* myodbc-usagenotes-apptips-microsoft-access::  Microsoft Access
* myodbc-usagenotes-apptips-microsoft-excel::  Microsoft Excel and Column Types
* myodbc-usagenotes-apptips-microsoft-visualbasic::  Microsoft Visual Basic
* myodbc-usagenotes-apptips-microsoft-visualinterdev::  Microsoft Visual InterDev
* myodbc-usagenotes-apptips-microsoft-visualobjects::  Visual Objects
* myodbc-usagenotes-apptips-microsoft-ado::  Microsoft ADO
* myodbc-usagenotes-apptips-microsoft-asp::  Using Connector/ODBC with Active Server Pages (ASP)
* myodbc-usagenotes-apptips-microsoft-vb-asp::  Using Connector/ODBC with Visual Basic (ADO, DAO and RDO) and ASP

The majority of Microsoft applications have been tested with
Connector/ODBC, including Microsoft Office, Microsoft Access and the
various programming languages supported within ASP and Microsoft Visual
Studio.


File: manual.info,  Node: myodbc-usagenotes-apptips-microsoft-access,  Next: myodbc-usagenotes-apptips-microsoft-excel,  Prev: myodbc-usagenotes-apptips-microsoft,  Up: myodbc-usagenotes-apptips-microsoft

30.1.7.8 Microsoft Access
.........................

To improve the integration between Microsoft Access and MySQL through
Connector/ODBC:

   * For all versions of Access, you should enable the Connector/ODBC
     `Return matching rows' option. For Access 2.0, you should
     additionally enable the `Simulate ODBC 1.0' option.

   * You should have a `TIMESTAMP' column in all tables that you want
     to be able to update. For maximum portability, don't use a length
     specification in the column declaration (which is unsupported
     within MySQL in versions earlier than 4.1).

   * You should have a primary key in each MySQL table you want to use
     with Access. If not, new or updated rows may show up as
     `#DELETED#'.

   * Use only `DOUBLE' float fields. Access fails when comparing with
     single-precision floats. The symptom usually is that new or
     updated rows may show up as `#DELETED#' or that you can't find or
     update rows.

   * If you are using Connector/ODBC to link to a table that has a
     `BIGINT' column, the results are displayed as `#DELETED#'. The work
     around solution is:

        * Have one more dummy column with `TIMESTAMP' as the data type.

        * Select the `Change BIGINT columns to INT' option in the
          connection dialog in ODBC DSN Administrator.

        * Delete the table link from Access and re-create it.

     Old records may still display as `#DELETED#', but newly
     added/updated records are displayed properly.

   * If you still get the error `Another user has changed your data'
     after adding a `TIMESTAMP' column, the following trick may help
     you:

     Don't use a `table' data sheet view.  Instead, create a form with
     the fields you want, and use that `form' data sheet view. You
     should set the `DefaultValue' property for the `TIMESTAMP' column
     to `NOW()'. It may be a good idea to hide the `TIMESTAMP' column
     from view so your users are not confused.

   * In some cases, Access may generate SQL statements that MySQL can't
     understand. You can fix this by selecting
     `"Query|SQLSpecific|Pass-Through"' from the Access menu.

   * On Windows NT, Access reports `BLOB' columns as `OLE OBJECTS'. If
     you want to have `MEMO' columns instead, you should change `BLOB'
     columns to `TEXT' with `ALTER TABLE'.

   * Access can't always handle the MySQL `DATE' column properly. If
     you have a problem with these, change the columns to `DATETIME'.

   * If you have in Access a column defined as `BYTE', Access tries to
     export this as `TINYINT' instead of `TINYINT UNSIGNED'. This gives
     you problems if you have values larger than 127 in the column.

   * If you have very large (long) tables in Access, it might take a
     very long time to open them. Or you might run low on virtual
     memory and eventually get an `ODBC Query Failed' error and the
     table cannot open.  To deal with this, select the following
     options:

        * Return Matching Rows (2)

        * Allow BIG Results (8).

     These add up to a value of 10 (`OPTION=10').

Some external articles and tips that may be useful when using Access,
ODBC and Connector/ODBC:

   * Read How to Trap ODBC Login Error Messages in Access
     (http://support.microsoft.com/support/kb/articles/Q124/9/01.asp?LN=EN-US&SD=gn&FR=0%3CP%3E)

   * Optimizing Access ODBC Applications

        * Optimizing for Client/Server Performance
          (http://support.microsoft.com/default.aspx?scid=kb;en-us;128808)

        * Tips for Converting Applications to Using ODBCDirect
          (http://support.microsoft.com/default.aspx?scid=kb;en-us;164481)

        * Tips for Optimizing Queries on Attached SQL Tables
          (http://support.microsoft.com/default.aspx?scid=kb;EN-US;q99321)

   * For a list of tools that can be used with Access and ODBC data
     sources, refer to converters
     (http://www.mysql.com/portal/software/convertors/) section for
     list of available tools.

MySQL Enterprise

MySQL Enterprise subscribers will find more information about using
ODBC with Access in Knowledge Base articles such as Use MySQL-Specific
Syntax with Microsoft Access (https://kb.mysql.com/view.php?id=5309). To
subscribe to MySQL Enterprise see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: myodbc-usagenotes-apptips-microsoft-excel,  Next: myodbc-usagenotes-apptips-microsoft-visualbasic,  Prev: myodbc-usagenotes-apptips-microsoft-access,  Up: myodbc-usagenotes-apptips-microsoft

30.1.7.9 Microsoft Excel and Column Types
.........................................

If you have problems importing data into Microsoft Excel, particularly
numerical, date, and time values, this is probably because of a bug in
Excel, where the column type of the source data is used to determine
the data type when that data is inserted into a cell within the
worksheet. The result is that Excel incorrectly identifies the content
and this affects both the display format and the data when it is used
within calculations.

To address this issue, use the `CONCAT()' function in your queries. The
use of `CONCAT()' forces Excel to treat the value as a string, which
Excel will then parse and usually correctly identify the embedded
information.

However, even with this option, some data may be incorrectly formatted,
even though the source data remains unchanged.  Use the `Format Cells'
option within Excel to change the format of the displayed information.


File: manual.info,  Node: myodbc-usagenotes-apptips-microsoft-visualbasic,  Next: myodbc-usagenotes-apptips-microsoft-visualinterdev,  Prev: myodbc-usagenotes-apptips-microsoft-excel,  Up: myodbc-usagenotes-apptips-microsoft

30.1.7.10 Microsoft Visual Basic
................................

To be able to update a table, you must define a primary key for the
table.

Visual Basic with ADO can't handle big integers. This means that some
queries like `SHOW PROCESSLIST' do not work properly. The fix is to use
`OPTION=16384' in the ODBC connect string or to select the `Change
BIGINT columns to INT' option in the Connector/ODBC connect screen.
You may also want to select the `Return matching rows' option.

MySQL Enterprise

MySQL Enterprise subscribers can find a discussion about using VBA in
the Knowledge Base article, MySQL-Specific Syntax with VBA
(https://kb.mysql.com/view.php?id=5308). To subscribe to MySQL
Enterprise see `http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: myodbc-usagenotes-apptips-microsoft-visualinterdev,  Next: myodbc-usagenotes-apptips-microsoft-visualobjects,  Prev: myodbc-usagenotes-apptips-microsoft-visualbasic,  Up: myodbc-usagenotes-apptips-microsoft

30.1.7.11 Microsoft Visual InterDev
...................................

If you have a `BIGINT' in your result, you may get the error
`[Microsoft][ODBC Driver Manager] Driver does not support this
parameter'. Try selecting the `Change BIGINT columns to INT' option in
the Connector/ODBC connect screen.


File: manual.info,  Node: myodbc-usagenotes-apptips-microsoft-visualobjects,  Next: myodbc-usagenotes-apptips-microsoft-ado,  Prev: myodbc-usagenotes-apptips-microsoft-visualinterdev,  Up: myodbc-usagenotes-apptips-microsoft

30.1.7.12 Visual Objects
........................

You should select the `Don't optimize column widths' option.


File: manual.info,  Node: myodbc-usagenotes-apptips-microsoft-ado,  Next: myodbc-usagenotes-apptips-microsoft-asp,  Prev: myodbc-usagenotes-apptips-microsoft-visualobjects,  Up: myodbc-usagenotes-apptips-microsoft

30.1.7.13 Microsoft ADO
.......................

When you are coding with the ADO API and Connector/ODBC, you need to
pay attention to some default properties that aren't supported by the
MySQL server. For example, using the `CursorLocation Property' as
`adUseServer' returns a result of -1 for the `RecordCount Property'. To
have the right value, you need to set this property to `adUseClient',
as shown in the VB code here:

     Dim myconn As New ADODB.Connection
     Dim myrs As New Recordset
     Dim mySQL As String
     Dim myrows As Long

     myconn.Open "DSN=MyODBCsample"
     mySQL = "SELECT * from user"
     myrs.Source = mySQL
     Set myrs.ActiveConnection = myconn
     myrs.CursorLocation = adUseClient
     myrs.Open
     myrows = myrs.RecordCount

     myrs.Close
     myconn.Close

Another workaround is to use a `SELECT COUNT(*)' statement for a
similar query to get the correct row count.

To find the number of rows affected by a specific SQL statement in ADO,
use the `RecordsAffected' property in the ADO execute method. For more
information on the usage of execute method, refer to
`http://msdn.microsoft.com/library/default.asp?url=/library/en-us/ado270/htm/mdmthcnnexecute.asp'.

For information, see ActiveX Data Objects(ADO) Frequently Asked
Questions
(http://support.microsoft.com/default.aspx?scid=kb;EN-US;q183606).


File: manual.info,  Node: myodbc-usagenotes-apptips-microsoft-asp,  Next: myodbc-usagenotes-apptips-microsoft-vb-asp,  Prev: myodbc-usagenotes-apptips-microsoft-ado,  Up: myodbc-usagenotes-apptips-microsoft

30.1.7.14 Using Connector/ODBC with Active Server Pages (ASP)
.............................................................

You should select the `Return matching rows' option in the DSN.

For more information about how to access MySQL via ASP using
Connector/ODBC, refer to the following articles:

   * Using MyODBC To Access Your MySQL Database Via ASP
     (http://www.devarticles.com/c/a/ASP/Using-MyODBC-To-Access-Your-MySQL-Database-Via-ASP/)

   * ASP and MySQL at DWAM.NT (http://www.dwam.net/mysql/asp_myodbc.asp)

A Frequently Asked Questions list for ASP can be found at
`http://support.microsoft.com/default.aspx?scid=/Support/ActiveServer/faq/data/adofaq.asp'.


File: manual.info,  Node: myodbc-usagenotes-apptips-microsoft-vb-asp,  Prev: myodbc-usagenotes-apptips-microsoft-asp,  Up: myodbc-usagenotes-apptips-microsoft

30.1.7.15 Using Connector/ODBC with Visual Basic (ADO, DAO and RDO) and ASP
...........................................................................

Some articles that may help with Visual Basic and ASP:

   * MySQL BLOB columns and Visual Basic 6
     (http://dev.mysql.com/tech-resources/articles/vb-blob-handling.html)
     by Mike Hillyer (<mike@openwin.org>).

   * How to map Visual basic data type to MySQL types
     (http://dev.mysql.com/tech-resources/articles/visual-basic-datatypes.html)
     by Mike Hillyer (<mike@openwin.org>).


File: manual.info,  Node: myodbc-usagenotes-apptips-borland,  Next: myodbc-usagenotes-apptips-coldfusion,  Prev: myodbc-usagenotes-apptips-microsoft,  Up: myodbc-usagenotes-apptips

30.1.7.16 Using Connector/ODBC with Borland Applications
........................................................

* Menu:

* myodbc-usagenotes-apptips-borland-builder::  Using Connector/ODBC with Borland Builder 4
* myodbc-usagenotes-apptips-borland-delphi::  Using Connector/ODBC with Delphi
* myodbc-usagenotes-apptips-borland-cppbuilder::  Using Connector/ODBC with C++ Builder

With all Borland applications where the Borland Database Engine (BDE)
is used, follow these steps to improve compatibility:

   * Update to BDE 3.2 or newer.

   * Enable the `Don't optimize column widths' option in the DSN.

   * Enabled the `Return matching rows' option in the DSN.


File: manual.info,  Node: myodbc-usagenotes-apptips-borland-builder,  Next: myodbc-usagenotes-apptips-borland-delphi,  Prev: myodbc-usagenotes-apptips-borland,  Up: myodbc-usagenotes-apptips-borland

30.1.7.17 Using Connector/ODBC with Borland Builder 4
.....................................................

When you start a query, you can use the `Active' property or the `Open'
method. Note that `Active' starts by automatically issuing a `SELECT *
FROM ...' query. That may not be a good thing if your tables are large.


File: manual.info,  Node: myodbc-usagenotes-apptips-borland-delphi,  Next: myodbc-usagenotes-apptips-borland-cppbuilder,  Prev: myodbc-usagenotes-apptips-borland-builder,  Up: myodbc-usagenotes-apptips-borland

30.1.7.18 Using Connector/ODBC with Delphi
..........................................

Also, here is some potentially useful Delphi code that sets up both an
ODBC entry and a BDE entry for Connector/ODBC.  The BDE entry requires
a BDE Alias Editor that is free at a Delphi Super Page near you.
(Thanks to Bryan Brunton <bryan@flesherfab.com> for this):

     fReg:= TRegistry.Create;
     fReg.OpenKey('\Software\ODBC\ODBC.INI\DocumentsFab', True);
     fReg.WriteString('Database', 'Documents');
     fReg.WriteString('Description', ' ');
     fReg.WriteString('Driver', 'C:\WINNT\System32\myodbc.dll');
     fReg.WriteString('Flag', '1');
     fReg.WriteString('Password', '');
     fReg.WriteString('Port', ' ');
     fReg.WriteString('Server', 'xmark');
     fReg.WriteString('User', 'winuser');
     fReg.OpenKey('\Software\ODBC\ODBC.INI\ODBC Data Sources', True);
     fReg.WriteString('DocumentsFab', 'MySQL');
     fReg.CloseKey;
     fReg.Free;

     Memo1.Lines.Add('DATABASE NAME=');
     Memo1.Lines.Add('USER NAME=');
     Memo1.Lines.Add('ODBC DSN=DocumentsFab');
     Memo1.Lines.Add('OPEN MODE=READ/WRITE');
     Memo1.Lines.Add('BATCH COUNT=200');
     Memo1.Lines.Add('LANGDRIVER=');
     Memo1.Lines.Add('MAX ROWS=-1');
     Memo1.Lines.Add('SCHEMA CACHE DIR=');
     Memo1.Lines.Add('SCHEMA CACHE SIZE=8');
     Memo1.Lines.Add('SCHEMA CACHE TIME=-1');
     Memo1.Lines.Add('SQLPASSTHRU MODE=SHARED AUTOCOMMIT');
     Memo1.Lines.Add('SQLQRYMODE=');
     Memo1.Lines.Add('ENABLE SCHEMA CACHE=FALSE');
     Memo1.Lines.Add('ENABLE BCD=FALSE');
     Memo1.Lines.Add('ROWSET SIZE=20');
     Memo1.Lines.Add('BLOBS TO CACHE=64');
     Memo1.Lines.Add('BLOB SIZE=32');

     AliasEditor.Add('DocumentsFab','MySQL',Memo1.Lines);


File: manual.info,  Node: myodbc-usagenotes-apptips-borland-cppbuilder,  Prev: myodbc-usagenotes-apptips-borland-delphi,  Up: myodbc-usagenotes-apptips-borland

30.1.7.19 Using Connector/ODBC with C++ Builder
...............................................

Tested with BDE 3.0. The only known problem is that when the table
schema changes, query fields are not updated. BDE, however, does not
seem to recognize primary keys, only the index named `PRIMARY',
although this has not been a problem.


File: manual.info,  Node: myodbc-usagenotes-apptips-coldfusion,  Next: myodbc-usagenotes-apptips-openoffice,  Prev: myodbc-usagenotes-apptips-borland,  Up: myodbc-usagenotes-apptips

30.1.7.20 Using Connector/ODBC with ColdFusion
..............................................

The following information is taken from the ColdFusion documentation:

Use the following information to configure ColdFusion Server for Linux
to use the `unixODBC' driver with Connector/ODBC for MySQL data
sources. You can download Connector/ODBC at
`http://dev.mysql.com/downloads/connector/odbc/'.

ColdFusion version 4.5.1 allows you to us the ColdFusion Administrator
to add the MySQL data source. However, the driver is not included with
ColdFusion version 4.5.1. Before the MySQL driver appears in the ODBC
data sources drop-down list, you must build and copy the Connector/ODBC
driver to `/opt/coldfusion/lib/libmyodbc.so'.

The Contrib directory contains the program `mydsn-XXX.zip' which allows
you to build and remove the DSN registry file for the Connector/ODBC
driver on ColdFusion applications.

For more information and guides on using ColdFusion and Connector/ODBC,
see the following external sites:

   * Troubleshooting Data Sources and Database Connectivity for Unix
     Platforms
     (http://www.macromedia.com/v1/handlers/index.cfm?ID=11328&Method=Full&PageCall=/support/index.cfm).


File: manual.info,  Node: myodbc-usagenotes-apptips-openoffice,  Next: myodbc-usagenotes-apptips-sambarserver,  Prev: myodbc-usagenotes-apptips-coldfusion,  Up: myodbc-usagenotes-apptips

30.1.7.21 Using Connector/ODBC with OpenOffice.org
..................................................

Open Office (`http://www.openoffice.org') How-to: MySQL + OpenOffice
(http://wiki.services.openoffice.org/wiki/Connect_MySQL_and_Base).
How-to: OpenOffice + MyODBC + unixODBC
(http://www.unixodbc.org/doc/OOoMySQL.pdf).


File: manual.info,  Node: myodbc-usagenotes-apptips-sambarserver,  Next: myodbc-usagenotes-apptips-datajunction,  Prev: myodbc-usagenotes-apptips-openoffice,  Up: myodbc-usagenotes-apptips

30.1.7.22 Using Connector/ODBC with Sambar Server
.................................................

Sambar Server (`http://www.sambarserver.info') How-to: MyODBC +
SambarServer + MySQL (http://www.sambarserver.info/article.php?sid=66).


File: manual.info,  Node: myodbc-usagenotes-apptips-datajunction,  Next: myodbc-usagenotes-apptips-vision,  Prev: myodbc-usagenotes-apptips-sambarserver,  Up: myodbc-usagenotes-apptips

30.1.7.23 Using Connector/ODBC with Pervasive Software DataJunction
...................................................................

You have to change it to output `VARCHAR' rather than `ENUM', as it
exports the latter in a manner that causes MySQL problems.


File: manual.info,  Node: myodbc-usagenotes-apptips-vision,  Prev: myodbc-usagenotes-apptips-datajunction,  Up: myodbc-usagenotes-apptips

30.1.7.24 Using Connector/ODBC with SunSystems Vision
.....................................................

You should select the `Return matching rows' option.


File: manual.info,  Node: myodbc-errors,  Prev: myodbc-usagenotes-apptips,  Up: myodbc-usagenotes

30.1.7.25 Connector/ODBC Errors and Resolutions (FAQ)
.....................................................

The following section details some common errors and their suggested
fix or alternative solution. If you are still experiencing problems,
use the Connector/ODBC mailing list; see *Note
myodbc-support-community::.

Many problems can be resolved by upgrading your Connector/ODBC drivers
to the latest available release. On Windows, you should also make sure
that you have the latest versions of the Microsoft Data Access
Components (MDAC) installed.

*Questions*
   * 31.1.7.3.1: I have installed Connector/ODBC on Windows XP x64
     Edition or Windows Server 2003 R2 x64. The installation completed
     successfully, but the Connector/ODBC driver does not appear in
     `ODBC Data Source Administrator'.

   * 31.1.7.3.2: When connecting or using the `Test' button in `ODBC
     Data Source Administrator' I get error 10061 (Cannot connect to
     server)

   * 31.1.7.3.3: The following error is reported when using
     transactions: `Transactions are not enabled'

   * 31.1.7.3.4: Access reports records as `#DELETED#' when inserting
     or updating records in linked tables.

   * 31.1.7.3.5: How do I handle Write Conflicts or Row Location errors?

   * 31.1.7.3.6: Exporting data from Access 97 to MySQL reports a
     `Syntax Error'.

   * 31.1.7.3.7: Exporting data from Microsoft DTS to MySQL reports a
     `Syntax Error'.

   * 31.1.7.3.8: Using ODBC.NET with Connector/ODBC, while fetching
     empty string (0 length), it starts giving the SQL_NO_DATA
     exception.

   * 31.1.7.3.9: Using `SELECT COUNT(*) FROM TBL_NAME' within Visual
     Basic and ASP returns an error.

   * 31.1.7.3.10: Using the `AppendChunk()' or `GetChunk()' ADO
     methods, the `Multiple-step operation generated errors. Check each
     status value' error is returned.

   * 31.1.7.3.11: Access Returns `Another user had modified the record
     that you have modified' while editing records on a Linked Table.

   * 31.1.7.3.12: When linking an application directly to the
     Connector/ODBC library under Unix/Linux, the application crashes.

   * 31.1.7.3.13: Applications in the Microsoft Office suite are unable
     to update tables that have `DATE' or `TIMESTAMP' columns.

   * 31.1.7.3.14: When connecting Connector/ODBC 5.x (Beta) to a MySQL
     4.x server, the error `1044 Access denied for user 'xxx'@'%' to
     database 'information_schema'' is returned.

   * 31.1.7.3.15: When calling `SQLTables', the error `S1T00' is
     returned, but I cannot find this in the list of error numbers for
     Connector/ODBC.

   * 31.1.7.3.16: When linking to tables in Access 2000 and generating
     links to tables programmatically, rather than through the table
     designer interface, you may get errors about tables not existing.

   * 31.1.7.3.17: When I try to use batched statements, the excution of
     the batched statements fails.

   * 31.1.7.3.18: When connecting to a MySQL server using ADODB and
     Excel, occasionally the application fails to communicate with the
     server and the error `Got an error reading communication packets'
     appears in the error log.

   * 31.1.7.3.19: When using some applications to access a MySQL server
     using C/ODBC and outer joins, an error is reported regarding the
     Outer Join Escape Sequence.

   * 31.1.7.3.20: I can correctly store extended characters in the
     database (Hebrew/CJK) using C/ODBC 5.1, but when I retrieve the
     data, the text is not formatted correctly and I get garbled
     characters.

   * 31.1.7.3.21: I have a duplicate MySQL Connector/ODBC entry within
     my `Installed Programs' list, but I cannot delete one of them.

   * 31.1.7.3.22: When submitting queries with parameter binding using
     `UPDATE', my field values are being truncated to 255 characters.

*Questions and Answers* *31.1.7.3.1: ** I have installed Connector/ODBC
on Windows XP x64 Edition or Windows Server 2003 R2 x64. The
installation completed successfully, but the Connector/ODBC driver does
not appear in `ODBC Data Source Administrator'.  *

This is not a bug, but is related to the way Windows x64 editions
operate with the ODBC driver. On Windows x64 editions, the
Connector/ODBC driver is installed in the `%SystemRoot%\SysWOW64'
folder.  However, the default `ODBC Data Source Administrator' that is
available through the `Administrative Tools' or `Control Panel' in
Windows x64 Editions is located in the `%SystemRoot%\system32' folder,
and only searches this folder for ODBC drivers.

On Windows x64 editions, you should use the ODBC administration tool
located at `%SystemRoot%\SysWOW64\odbcad32.exe', this will correctly
locate the installed Connector/ODBC drivers and enable you to create a
Connector/ODBC DSN.

This issue was originally reported as Bug#20301
(http://bugs.mysql.com/20301).

*31.1.7.3.2: ** When connecting or using the `Test' button in `ODBC
Data Source Administrator' I get error 10061 (Cannot connect to server)
*

This error can be raised by a number of different issues, including
server problems, network problems, and firewall and port blocking
problems. For more information, see *Note can-not-connect-to-server::.

*31.1.7.3.3: ** The following error is reported when using transactions:
`Transactions are not enabled' *

This error indicates that you are trying to use transactions with a
MySQL table that does not support transactions. Transactions are
supported within MySQL when using the `InnoDB' database engine. In
versions of MySQL before Mysql 5.1 you may also use the `BDB' engine.

You should check the following before continuing:

   * Verify that your MySQL server supports a transactional database
     engine. Use `SHOW ENGINES' to obtain a list of the available
     engine types.

   * Verify that the tables you are updating use a transaction database
     engine.

   * Ensure that you have not enabled the `disable transactions' option
     in your DSN.

*31.1.7.3.4: ** Access reports records as `#DELETED#' when inserting or
updating records in linked tables.  *

If the inserted or updated records are shown as `#DELETED#' in the
access, then:

   * If you are using Access 2000, you should get and install the
     newest (version 2.6 or higher) Microsoft MDAC (`Microsoft Data
     Access Components') from `http://support.microsoft.com/kb/110093'.
     This fixes a bug in Access that when you export data to MySQL, the
     table and column names aren't specified.

     You should also get and apply the Microsoft Jet 4.0 Service Pack 5
     (SP5) which can be found at
     `http://support.microsoft.com/default.aspx?scid=kb;EN-US;q239114'.
     This fixes some cases where columns are marked as `#DELETED#' in
     Access.

   * For all versions of Access, you should enable the Connector/ODBC
     `Return matching rows' option. For Access 2.0, you should
     additionally enable the `Simulate ODBC 1.0' option.

   * You should have a timestamp in all tables that you want to be able
     to update.

   * You should have a primary key in the table. If not, new or updated
     rows may show up as `#DELETED#'.

   * Use only `DOUBLE' float fields.  Access fails when comparing with
     single-precision floats. The symptom usually is that new or updated
     rows may show up as `#DELETED#' or that you can't find or update
     rows.

   * If you are using Connector/ODBC to link to a table that has a
     `BIGINT' column, the results are displayed as `#DELETED'.  The
     work around solution is:

        * Have one more dummy column with `TIMESTAMP' as the data type.

        * Select the `Change BIGINT columns to INT' option in the
          connection dialog in ODBC DSN Administrator.

        * Delete the table link from Access and re-create it.

     Old records still display as `#DELETED#', but newly added/updated
     records are displayed properly.

*31.1.7.3.5: ** How do I handle Write Conflicts or Row Location errors?
*

If you see the following errors, select the `Return Matching Rows'
option in the DSN configuration dialog, or specify `OPTION=2', as the
connection parameter:

     Write Conflict. Another user has changed your data.

     Row cannot be located for updating. Some values may have been changed
     since it was last read.

*31.1.7.3.6: ** Exporting data from Access 97 to MySQL reports a
`Syntax Error'.  *

This error is specific to Access 97 and versions of Connector/ODBC
earlier than 3.51.02. Update to the latest version of the
Connector/ODBC driver to resolve this problem.

*31.1.7.3.7: ** Exporting data from Microsoft DTS to MySQL reports a
`Syntax Error'.  *

This error occurs only with MySQL tables using the `TEXT' or `VARCHAR'
data types. You can fix this error by upgrading your Connector/ODBC
driver to version 3.51.02 or higher.

*31.1.7.3.8: ** Using ODBC.NET with Connector/ODBC, while fetching empty
string (0 length), it starts giving the SQL_NO_DATA exception.  *

You can get the patch that addresses this problem from
`http://support.microsoft.com/default.aspx?scid=kb;EN-US;q319243'.

*31.1.7.3.9: ** Using `SELECT COUNT(*) FROM TBL_NAME' within Visual
Basic and ASP returns an error.  *

This error occurs because the `COUNT(*)' expression is returning a
`BIGINT', and ADO can't make sense of a number this big. Select the
`Change BIGINT columns to INT' option (option value 16384).

*31.1.7.3.10: ** Using the `AppendChunk()' or `GetChunk()' ADO methods,
the `Multiple-step operation generated errors. Check each status value'
error is returned.  *

The `GetChunk()' and `AppendChunk()' methods from ADO doesn't work as
expected when the cursor location is specified as `adUseServer'. On the
other hand, you can overcome this error by using `adUseClient'.

A simple example can be found from
`http://www.dwam.net/iishelp/ado/docs/adomth02_4.htm'

*31.1.7.3.11: ** Access Returns `Another user had modified the record
that you have modified' while editing records on a Linked Table.  *

In most cases, this can be solved by doing one of the following things:

   * Add a primary key for the table if one doesn't exist.

   * Add a timestamp column if one doesn't exist.

   * Only use double-precision float fields. Some programs may fail
     when they compare single-precision floats.

If these strategies don't help, you should start by making a log file
from the ODBC manager (the log you get when requesting logs from
ODBCADMIN) and a Connector/ODBC log to help you figure out why things
go wrong. For instructions, see *Note myodbc-configuration-trace::.

*31.1.7.3.12: ** When linking an application directly to the
Connector/ODBC library under Unix/Linux, the application crashes.  *

Connector/ODBC 3.51 under Unix/Linux is not compatible with direct
application linking. You must use a driver manager, such as iODBC or
unixODBC to connect to an ODBC source.

*31.1.7.3.13: ** Applications in the Microsoft Office suite are unable
to update tables that have `DATE' or `TIMESTAMP' columns.  *

This is a known issue with Connector/ODBC. You must ensure that the
field has a default value (rather than `NULL' and that the default
value is non-zeo (i.e. the default value is not `0000-00-00 00:00:00').

*31.1.7.3.14: ** When connecting Connector/ODBC 5.x (Beta) to a MySQL
4.x server, the error `1044 Access denied for user 'xxx'@'%' to
database 'information_schema'' is returned.  *

Connector/ODBC 5.x is designed to work with MySQL 5.0 or later, taking
advantage of the `INFORMATION_SCHEMA' database to determine data
definition information. Support for MySQL 4.1 is planned for the final
release.

*31.1.7.3.15: ** When calling `SQLTables', the error `S1T00' is
returned, but I cannot find this in the list of error numbers for
Connector/ODBC.  *

The `S1T00' error indicates that a general timeout has occurred within
the ODBC system and is not a MySQL error. Typically it indicates that
the connection you are using is stale, the server is too busy to accept
your request or that the server has gone away.

*31.1.7.3.16: ** When linking to tables in Access 2000 and generating
links to tables programmatically, rather than through the table
designer interface, you may get errors about tables not existing.  *

There is a known issue with a specific version of the `msjet40.dll'
that exhibits this issue.  The version affected is 4.0.9025.0.
Reverting to an older version will enable you to create the links. If
you have recently updated your version, check your `WINDOWS' directory
for the older version of the file and copy it to the drivers directory.

*31.1.7.3.17: ** When I try to use batched statements, the excution of
the batched statements fails.  *

Batched statement support was added in 3.51.18. Support for batched
statements is not enabled by default. You must enable option
`FLAG_MULTI_STATEMENTS', value 67108864, or select the `Allow multiple
statements' flag within a GUI configuration.

*31.1.7.3.18: ** When connecting to a MySQL server using ADODB and
Excel, occasionally the application fails to communicate with the
server and the error `Got an error reading communication packets'
appears in the error log.  *

This error may be related to Keyboard Logger 1.1 from PanteraSoft.com,
which is known to interfere with the network communication between
MySQL Connector/ODBC and MySQL.

*31.1.7.3.19: ** When using some applications to access a MySQL server
using C/ODBC and outer joins, an error is reported regarding the Outer
Join Escape Sequence.  *

This is a known issue with MySQL Connector/ODBC which is not correctly
parsing the "Outer Join Escape Sequence", as per the specs at Microsoft
ODBC Specs (http://msdn2.microsoft.com/en-us/library/ms710299.aspx).
Currently, Connector/ODBC will return value > 0 when asked for
`SQL_OJ_CAPABILITIES' even though no parsing takes place in the driver
to handle the outer join escape sequence.

*31.1.7.3.20: ** I can correctly store extended characters in the
database (Hebrew/CJK) using C/ODBC 5.1, but when I retrieve the data,
the text is not formatted correctly and I get garbled characters.  *

When using ASP and UTF8 characters you should add the following to your
ASP files to ensure that the data returned is correctly encoded:

     Response.CodePage = 65001
     Response.CharSet = "utf-8"

*31.1.7.3.21: ** I have a duplicate MySQL Connector/ODBC entry within my
`Installed Programs' list, but I cannot delete one of them.  *

This problem can occur when you upgrade an existing Connector/ODBC
installation, rather than removing and then installing the updated
version.

*Warning*:

To fix the problem you should use any working uninstallers to remove
existing installations and then may have to edit the contents of the
registry. Make sure you have a backup of your registry information
before attempting any editing of the registry contents.

*31.1.7.3.22: ** When submitting queries with parameter binding using
`UPDATE', my field values are being truncated to 255 characters.  *

You should ensure that the `FLAG_BIG_PACKETS' option is set for your
connection. This removes the 255 character limitation on bound
parameters.


File: manual.info,  Node: myodbc-support,  Prev: myodbc-usagenotes,  Up: myodbc-connector

30.1.8 Connector/ODBC Support
-----------------------------

* Menu:

* myodbc-support-community::     Connector/ODBC Community Support
* myodbc-support-bug-report::    How to Report Connector/ODBC Problems or Bugs
* myodbc-support-patch-submission::  How to Submit a Connector/ODBC Patch
* myodbc-support-changehistory::  Connector/ODBC Change History
* myodbc-support-credits::       Credits

There are many different places where you can get support for using
Connector/ODBC. You should always try the Connector/ODBC Mailing List
or Connector/ODBC Forum. See *Note myodbc-support-community::, for help
before reporting a specific bug or issue to MySQL.


File: manual.info,  Node: myodbc-support-community,  Next: myodbc-support-bug-report,  Prev: myodbc-support,  Up: myodbc-support

30.1.8.1 Connector/ODBC Community Support
.........................................

MySQL AB provides assistance to the user community by means of its
mailing lists. For Connector/ODBC-related issues, you can get help from
experienced users by using the <myodbc@lists.mysql.com> mailing list.
Archives are available online at `http://lists.mysql.com/myodbc'.

For information about subscribing to MySQL mailing lists or to browse
list archives, visit `http://lists.mysql.com/'. See *Note
mailing-lists::.

Community support from experienced users is also available through the
ODBC Forum (http://forums.mysql.com/list.php?37). You may also find
help from other users in the other MySQL Forums, located at
`http://forums.mysql.com'. See *Note forums::.


File: manual.info,  Node: myodbc-support-bug-report,  Next: myodbc-support-patch-submission,  Prev: myodbc-support-community,  Up: myodbc-support

30.1.8.2 How to Report Connector/ODBC Problems or Bugs
......................................................

If you encounter difficulties or problems with Connector/ODBC, you
should start by making a log file from the `ODBC Manager' (the log you
get when requesting logs from `ODBC ADMIN') and Connector/ODBC. The
procedure for doing this is described in *Note
myodbc-configuration-trace::.

Check the Connector/ODBC trace file to find out what could be wrong.
You should be able to determine what statements were issued by
searching for the string `>mysql_real_query' in the `myodbc.log' file.

You should also try issuing the statements from the `mysql' client
program or from `admndemo'. This helps you determine whether the error
is in Connector/ODBC or MySQL.

If you find out something is wrong, please only send the relevant rows
(maximum 40 rows) to the `myodbc' mailing list. See *Note
mailing-lists::. Please never send the whole Connector/ODBC or ODBC log
file!

You should ideally include the following information with the email:

   * Operating system and version

   * Connector/ODBC version

   * ODBC Driver Manager type and version

   * MySQL server version

   * ODBC trace from Driver Manager

   * Connector/ODBC log file from Connector/ODBC driver

   * Simple reproducible sample

Remember that the more information you can supply to us, the more
likely it is that we can fix the problem!

Also, before posting the bug, check the MyODBC mailing list archive at
`http://lists.mysql.com/myodbc'.

If you are unable to find out what's wrong, the last option is to
create an archive in `tar' or Zip format that contains a Connector/ODBC
trace file, the ODBC log file, and a `README' file that explains the
problem. You can send this to `ftp://ftp.mysql.com/pub/mysql/upload/'.
Only MySQL engineers have access to the files you upload, and we are
very discreet with the data.

If you can create a program that also demonstrates the problem, please
include it in the archive as well.

If the program works with another SQL server, you should include an
ODBC log file where you perform exactly the same SQL statements so that
we can compare the results between the two systems.

Remember that the more information you can supply to us, the more
likely it is that we can fix the problem.


File: manual.info,  Node: myodbc-support-patch-submission,  Next: myodbc-support-changehistory,  Prev: myodbc-support-bug-report,  Up: myodbc-support

30.1.8.3 How to Submit a Connector/ODBC Patch
.............................................

You can send a patch or suggest a better solution for any existing code
or problems by sending a mail message to <myodbc@lists.mysql.com>.


File: manual.info,  Node: myodbc-support-changehistory,  Next: myodbc-support-credits,  Prev: myodbc-support-patch-submission,  Up: myodbc-support

30.1.8.4 Connector/ODBC Change History
......................................

The Connector/ODBC Change History (Changelog) is located with the main
Changelog for MySQL. See *Note myodbc-news::.


File: manual.info,  Node: myodbc-support-credits,  Prev: myodbc-support-changehistory,  Up: myodbc-support

30.1.8.5 Credits
................

These are the developers that have worked on the Connector/ODBC and
Connector/ODBC 3.51 Drivers from MySQL AB.

   * Michael (Monty) Widenius

   * Venu Anuganti

   * Peter Harvey


File: manual.info,  Node: connector-net,  Next: connector-vstudio,  Prev: myodbc-connector,  Up: connectors

30.2 MySQL Connector/NET
========================

* Menu:

* connector-net-versions::       Connector/NET Versions
* connector-net-installation::   Connector/NET Installation
* connector-net-examples::       Connector/NET Examples and Usage Guide
* connector-net-ref::            Connector/NET Reference
* connector-net-using::          Connector/NET Notes and Tips
* connect-net-support::          Connector/NET Support

Connector/NET enables developers to easily create .NET applications
that require secure, high-performance data connectivity with MySQL.  It
implements the required ADO.NET interfaces and integrates into ADO.NET
aware tools. Developers can build applications using their choice of
.NET languages. Connector/NET is a fully managed ADO.NET driver written
in 100% pure C#.

Connector/NET includes full support for:

   * MySQL 5.0 features (such as stored procedures)

   * MySQL 4.1 features (server-side prepared statements, Unicode, and
     shared memory access, and so forth)

   * Large-packet support for sending and receiving rows and BLOBs up
     to 2 gigabytes in size.

   * Protocol compression which allows for compressing the data stream
     between the client and server.

   * Support for connecting using TCP/IP sockets, named pipes, or
     shared memory on Windows.

   * Support for connecting using TCP/IP sockets or Unix sockets on
     Unix.

   * Support for the Open Source Mono framework developed by Novell.

   * Fully managed, does not utilize the MySQL client library.

This document is intended as a user's guide to Connector/NET and
includes a full syntax reference. Syntax information is also included
within the `Documentation.chm' file included with the Connector/NET
distribution.

If you are using MySQL 5.0 or later, and Visual Studio as your
development environment, you may want also want to use the MySQL Visual
Studio Plugin. The plugin acts as a DDEX (Data Designer Extensibility)
provider, enabling you to use the data design tools within Visual
Studio to manipulate the schema and objects within a MySQL database.
For more information, see *Note connector-vstudio::.

*Note*:

Connector/NET 5.1.2 and later include the Visual Studio Plugin by
default.

*Key topics:*

   * For connection string properties when using the MySqlConnection
     class, see *Note
     connector-net-examples-mysqlconnection-connectionstring::.


File: manual.info,  Node: connector-net-versions,  Next: connector-net-installation,  Prev: connector-net,  Up: connector-net

30.2.1 Connector/NET Versions
-----------------------------

There are currently three versions of Connector/NET available:

   * Connector/NET 1.0 includes support for MySQL 4.0, and MySQL 5.0
     features, and full compatibility with the ADO.NET driver interface.

     Connector/NET 5.0 includes support for MySQL 4.0, MySQL 4.1, MySQL
     5.0 and MySQL 5.1 features. Connector/NET 5.0 also includes full
     support for the ADO.Net 2.0 interfaces and subclasses, includes
     support for the usage advisor and performance monitor (PerfMon)
     hooks.

     Connector/NET 5.1 includes support for MySQL 4.0, MySQL 5.0, MySQL
     5.1 and MySQL 6.0 (Falcon Preview) features.  Connector/NET 5.1
     also includes support for a new membership/role provider, Compact
     Framework 2.0, a new stored procedure parser and improvements to
     `GetSchema'. Connector/NET 5.1 also includes the Visual Studio
     Plugin as a standard installable component.

*Note*:

Version numbers for MySQL products are formatted as X.X.X.  However,
Windows tools (Control Panel, properties display) may show the version
numbers as XX.XX.XX. For example, the official MySQL formatted version
number 5.0.9 may be displayed by Windows tools as 5.00.09. The two
versions are the same; only the number display format is different.


File: manual.info,  Node: connector-net-installation,  Next: connector-net-examples,  Prev: connector-net-versions,  Up: connector-net

30.2.2 Connector/NET Installation
---------------------------------

* Menu:

* connector-net-installation-windows::  Installing Connector/NET on Windows
* connector-net-installation-unix::  Installing Connector/NET on Unix with Mono
* connector-net-installation-source::  Installing Connector/NET using the Source

Connector/NET runs on any platform that supports the .NET framework.
The .NET framework is primarily supported on recent versions of
Microsoft Windows, and is supported on Linux through the Open Source
Mono framework (see `http://www.mono-project.com').

Connector/NET is available for download from
`http://dev.mysql.com/downloads/connector/net/1.0.html'.


File: manual.info,  Node: connector-net-installation-windows,  Next: connector-net-installation-unix,  Prev: connector-net-installation,  Up: connector-net-installation

30.2.2.1 Installing Connector/NET on Windows
............................................

* Menu:

* connector-net-installation-binary-windows-installer::  Installing Connector/NET using the Installer
* connector-net-installation-binary-windows-zip::  Installing Connector/NET using the Zip package

On Windows, installation is supported either through a binary
installation process or by downloading a Zip file with the
Connector/NET components.

Before installing, you should ensure that your system is up to date,
including installing the latest version of the .NET Framework.


File: manual.info,  Node: connector-net-installation-binary-windows-installer,  Next: connector-net-installation-binary-windows-zip,  Prev: connector-net-installation-windows,  Up: connector-net-installation-windows

30.2.2.2 Installing Connector/NET using the Installer
.....................................................

Using the installer is the most straightforward method of installing
Connector/NET on Windows and the installed components include the
source code, test code and full reference documentation.

Connector/NET is installed through the use of a Windows Installer
(`.msi') installation package, which can be used to install
Connector/NET on all Windows operating systems. The MSI package in
contained within a ZIP archive named `mysql-connector-net-VERSION.zip',
where VERSION indicates the Connector/NET version.

To install Connector/NET:

  1. Double click on the MSI installer file extracted from the Zip you
     downloaded. Click `Next' to start the installation.

     Connector/NET Windows Installer - Welcome

  2. You must choose the type of installation that you want to perform.

     Connector/NET Windows Installer - Installation type

     For most situations, the Typical installation will be suitable.
     Click the `Typical' button and proceed to Step 5. A Complete
     installation installs all the available files. To conduct a
     Complete installation, click the `Complete' button and proceed to
     step 5. If you want to customize your installation, including
     choosing the components to install and some installation options,
     click the `Custom' button and proceed to Step 3.

     The Connector/NET installer will register the connector within the
     Global Assembly Cache (GAC) - this will make the Connector/NET
     component available to all applications, not just those where you
     explicitly reference the Connector/NET component. The installer
     will also create the necessary links in the Start menu to the
     documentation and release notes.

  3. If you have chosen a custom installation, you can select the
     individual components that you want to install, including the core
     interface component, supporting documentation (a CHM file) samples
     and examples and the source code. Select the items, and their
     installation level, and then click `Next' to continue the
     installation.

     *Note*:

     For Connector/NET 1.0.8 or lower and Connector 5.0.4 and lower the
     installer will attempt to install binaries for both 1.x and 2.x of
     the .NET Framework. If you only have one version of the framework
     installed, the connector installation may fail. If this happens,
     you can choose the framework version to be installed through the
     custom installation step.

     Connector/NET Windows Installer - Custom setup

  4. You will be given a final opportunity to confirm the installation.
     Click `Install' to copy and install the files onto your machine.

     Connector/NET Windows Installer - Confirming installation

  5. Once the installation has been completed, click `Finish' to exit
     the installer.

Unless you choose otherwise, Connector/NET is installed in `C:\Program
Files\MySQL\MySQL Connector Net X.X.X', where X.X.X is replaced with
the version of Connector/NET you are installing. New installations do
not overwrite existing versions of Connector/NET.

Depending on your installation type, the installed components will
include some or all of the following components:

   * `bin' - Connector/NET MySQL libraries for different versions of
     the .NET environment.

   * `docs' - contains a CHM of the Connector/NET documentation.

   * `samples' - sample code and applications that use the
     Connector/NET component.

   * `src' - the source code for the Connector/NET component.

You may also use the `/quiet' or `/q' command-line option with the
`msiexec' tool to install the Connector/NET package automatically
(using the default options) with no notification to the user. Using
this option you cannot select options and no prompts, messages or
dialog boxes will be displayed.

     C:\> msiexec /package conector-net.msi /quiet

To provide a progress bar to the user during automatic installation,
but still without presenting the user with a dialog box of the ability
to select options, use the `/passive' option.


File: manual.info,  Node: connector-net-installation-binary-windows-zip,  Prev: connector-net-installation-binary-windows-installer,  Up: connector-net-installation-windows

30.2.2.3 Installing Connector/NET using the Zip package
.......................................................

If you are having problems running the installer, you can download a
.zip file without an installer as an alternative.  That file is called
`mysql-connector-net-VERSION-noinstall.zip'.  Once downloaded, you can
extract the files to a location of your choice.

The .zip file contains the following directories:

   * `bin' - Connector/NET MySQL libraries for different versions of
     the .NET environment.

   * `doc' - contains a CHM of the Connector/NET documentation.

   * `Samples' - sample code and applications that use the
     Connector/NET component.

   * `mysqlclient' - the source code for the Connector/NET component.

   * `testsuite' - the test suite used to verify the operation of the
     Connector/NET component.


File: manual.info,  Node: connector-net-installation-unix,  Next: connector-net-installation-source,  Prev: connector-net-installation-windows,  Up: connector-net-installation

30.2.2.4 Installing Connector/NET on Unix with Mono
...................................................

There is no installer available for installing the Connector/NET
component on your Unix installation. However, the installation is very
simple. Before installing, please ensure that you have a working Mono
project installation.

Note that you should only install the Connector/NET component on Unix
environments where you want to connect to a MySQL server through the
Mono project. If you are deploying or developing on a different
environment such as Java or Perl then you should use a more appropriate
connectivity component. See *Note connectors::, or *Note apis::, for
more information.

To install Connector/NET on Unix/Mono:

  1. Download the `mysql-connector-net-VERSION-noinstall.zip' and
     extract the contents.

  2. Copy the `MySql.Data.dll' file to your Mono project installation
     folder.

  3. You must register the Connector/NET component in the Global
     Assembly Cache using the `gacutil' command:

          shell> gacutil /i MySql.Data.dll

Once installed, applications that are compiled with the Connector/NET
component need no further changes. However, you must ensure that when
you compile your applications you include the Connector/NET component
using the `-r:MySqlData.dll' command-line option.


File: manual.info,  Node: connector-net-installation-source,  Prev: connector-net-installation-unix,  Up: connector-net-installation

30.2.2.5 Installing Connector/NET using the Source
..................................................

*Caution*:

You should read this section only if you are interested in helping us
test our new code. If you just want to get Connector/NET up and running
on your system, you should use a standard release distribution.

To be able to access the Connector/NET source tree, you must have
Subversion installed. Subversion is freely available from
`http://subversion.tigris.org/'.

The most recent development source tree is available from our public
Subversion trees at `http://dev.mysql.com/tech-resources/sources.html'.

To checkout out the Connector/NET sources, change to the directory
where you want the copy of the Connector/NET tree to be stored, then
use the following command:

     shell> svn co
     http://svn.mysql.com/svnpublic/connector-net

A Visual Studio project is included in the source which you can use to
build Connector/NET.


File: manual.info,  Node: connector-net-examples,  Next: connector-net-ref,  Prev: connector-net-installation,  Up: connector-net

30.2.3 Connector/NET Examples and Usage Guide
---------------------------------------------

* Menu:

* connector-net-examples-mysqlcommand::  Using `MySqlCommand'
* connector-net-examples-mysqlcommandbuilder::  Using `MySqlCommandBuilder'
* connector-net-examples-mysqlconnection::  Using `MySqlConnection'
* connector-net-examples-mysqldataadapter::  Using `MySqlDataAdapter'
* connector-net-examples-mysqldatareader::  Using `MySqlDataReader'
* connector-net-examples-mysqlexception::  Using `MySqlException'
* connector-net-examples-mysqlparameter::  Using `MySqlParameter'
* connector-net-examples-mysqlparametercollection::  Using `MySqlParameterCollection'
* connector-net-examples-mysqltransaction::  Using `MySqlTransaction'

Connector/NET comprises several classes that are used to connect to the
database, execute queries and statements, and manage query results.

The following are the major classes of Connector/NET:

   * `MySqlCommand': Represents an SQL statement to execute against a
     MySQL database.

   * `MySqlCommandBuilder': Automatically generates single-table
     commands used to reconcile changes made to a DataSet with the
     associated MySQL database.

   * `MySqlConnection': Represents an open connection to a MySQL Server
     database.

   * `MySqlDataAdapter': Represents a set of data commands and a
     database connection that are used to fill a data set and update a
     MySQL database.

   * `MySqlDataReader': Provides a means of reading a forward-only
     stream of rows from a MySQL database.

   * `MySqlException': The exception that is thrown when MySQL returns
     an error.

   * `MySqlHelper': Helper class that makes it easier to work with the
     provider.

   * `MySqlTransaction': Represents an SQL transaction to be made in a
     MySQL database.

This section contains basic information and examples for each of the
above classes. For a more detailed reference guide please see *Note
connector-net-ref::.


File: manual.info,  Node: connector-net-examples-mysqlcommand,  Next: connector-net-examples-mysqlcommandbuilder,  Prev: connector-net-examples,  Up: connector-net-examples

30.2.3.1 Using `MySqlCommand'
.............................

* Menu:

* connector-net-examples-mysqlcommand-ctor1::  Class MySqlCommand Constructor Form 1
* connector-net-examples-mysqlcommand-ctor2::  Class MySqlCommand Constructor Form 2
* connector-net-examples-mysqlcommand-ctor3::  Class MySqlCommand Constructor Form 3
* connector-net-examples-mysqlcommand-ctor4::  Class MySqlCommand Constructor Form 4
* connector-net-examples-mysqlcommand-executenonquery::  ExecuteNonQuery
* connector-net-examples-mysqlcommand-executereader1::  ExecuteReader1
* connector-net-examples-mysqlcommand-executereader::  Using `ExecuteReader'
* connector-net-examples-mysqlcommand-prepare::  Using `Prepare'
* connector-net-examples-mysqlcommand-executescalar::  ExecuteScalar
* connector-net-examples-mysqlcommand-commandtext::  CommandText
* connector-net-examples-mysqlcommand-commandtimeout::  CommandTimeout
* connector-net-examples-mysqlcommand-commandtype::  CommandType
* connector-net-examples-mysqlcommand-connection::  Connection
* connector-net-examples-mysqlcommand-isprepared::  IsPrepared
* connector-net-examples-mysqlcommand-parameters::  Parameters
* connector-net-examples-mysqlcommand-transaction::  Transaction
* connector-net-examples-mysqlcommand-updatedrowsource::  UpdatedRowSource

Represents a SQL statement to execute against a MySQL database.  This
class cannot be inherited.

`MySqlCommand' features the following methods for executing commands at
a MySQL database:

* Item*                              * Description*
* *Note ExecuteReader:               Executes commands that return rows.
connector-net-examples-mysqlcommand-executereader.
*                                    
* *Note ExecuteNonQuery:             Executes commands such as SQL
connector-net-examples-mysqlcommand-executenonquery.INSERT, DELETE, and UPDATE
*                                    statements.
* *Note ExecuteScalar:               Retrieves a single value (for
connector-net-examples-mysqlcommand-executescalar.example, an aggregate value) from a
*                                    database.

You can reset the `CommandText' property and reuse the `MySqlCommand'
object. However, you must close the *Note MySqlDataReader:
connector-net-examples-mysqldatareader.  before you can execute a new
or previous command.

If a *Note MySqlException: connector-net-examples-mysqlexception.  is
generated by the method executing a `MySqlCommand', the *Note
MySqlConnection: connector-net-examples-mysqlconnection.  remains open.
It is the responsibility of the programmer to close the connection.

*Note*:

Using the '@' symbol for parameters is now the preferred approach
although the old pattern of using '?' is still supported.

Please be aware however that using '@' can cause conflicts when user
variables are also used. To help with this situation please see the
documentation on the `Allow User Variables' connection string option,
which can be found here: *Note
connector-net-examples-mysqlconnection-connectionstring::.  The `Old
Syntax' connection string option has now been deprecated.

*Examples*

The following example creates a *Note MySqlCommand:
connector-net-examples-mysqlcommand.  and a `MySqlConnection'. The
`MySqlConnection' is opened and set as the *Note Connection:
connector-net-examples-mysqlconnection.  for the `MySqlCommand'. The
example then calls *Note ExecuteNonQuery:
connector-net-examples-mysqlcommand-executenonquery, and closes the
connection. To accomplish this, the `ExecuteNonQuery' is passed a
connection string and a query string that is a SQL INSERT statement.

Visual Basic example:

       Public Sub InsertRow(myConnectionString As String)
       " If the connection string is null, use a default.
       If myConnectionString = "" Then
         myConnectionString = "Database=Test;Data Source=localhost;User Id=username;Password=pass"
       End If
       Dim myConnection As New MySqlConnection(myConnectionString)
       Dim myInsertQuery As String = "INSERT INTO Orders (id, customerId, amount) Values(1001, 23, 30.66)"
       Dim myCommand As New MySqlCommand(myInsertQuery)
       myCommand.Connection = myConnection
       myConnection.Open()
       myCommand.ExecuteNonQuery()
       myCommand.Connection.Close()
     End Sub

C# example:

       public void InsertRow(string myConnectionString)
     {
       // If the connection string is null, use a default.
       if(myConnectionString == "")
       {
         myConnectionString = "Database=Test;Data Source=localhost;User Id=username;Password=pass";
       }
       MySqlConnection myConnection = new MySqlConnection(myConnectionString);
       string myInsertQuery = "INSERT INTO Orders (id, customerId, amount) Values(1001, 23, 30.66)";
       MySqlCommand myCommand = new MySqlCommand(myInsertQuery);
       myCommand.Connection = myConnection;
       myConnection.Open();
       myCommand.ExecuteNonQuery();
       myCommand.Connection.Close();
     }


File: manual.info,  Node: connector-net-examples-mysqlcommand-ctor1,  Next: connector-net-examples-mysqlcommand-ctor2,  Prev: connector-net-examples-mysqlcommand,  Up: connector-net-examples-mysqlcommand

30.2.3.2 Class MySqlCommand Constructor Form 1
..............................................

*Overload methods for MySqlCommand*

Initializes a new instance of the MySqlCommand class.

*Examples*

The following example creates a MySqlCommand and sets some of its
properties.

*Note*:

This example shows how to use one of the overloaded versions of the
`MySqlCommand' constructor. For other examples that might be available,
see the individual overload topics.

Visual Basic example:

       Public Sub CreateMySqlCommand()
         Dim myConnection As New MySqlConnection _
             ("Persist Security Info=False;database=test;server=myServer")
         myConnection.Open()
         Dim myTrans As MySqlTransaction = myConnection.BeginTransaction()
         Dim mySelectQuery As String = "SELECT * FROM MyTable"
         Dim myCommand As New MySqlCommand(mySelectQuery, myConnection, myTrans)
         myCommand.CommandTimeout = 20
       End Sub

C# example:

       public void CreateMySqlCommand()
       {
         MySqlConnection myConnection = new MySqlConnection("Persist Security Info=False;
           database=test;server=myServer");
         myConnection.Open();
         MySqlTransaction myTrans = myConnection.BeginTransaction();
         string mySelectQuery = "SELECT * FROM myTable";
         MySqlCommand myCommand = new MySqlCommand(mySelectQuery, myConnection,myTrans);
         myCommand.CommandTimeout = 20;
       }

C++ example:

       public:
       void CreateMySqlCommand()
       {
         MySqlConnection* myConnection = new MySqlConnection(S"Persist Security Info=False;
           database=test;server=myServer");
         myConnection->Open();
         MySqlTransaction* myTrans = myConnection->BeginTransaction();
         String* mySelectQuery = S"SELECT * FROM myTable";
         MySqlCommand* myCommand = new MySqlCommand(mySelectQuery, myConnection, myTrans);
         myCommand->CommandTimeout = 20;
       };

Initializes a new instance of the MySqlCommand class.

The base constructor initializes all fields to their default values.
The following table shows initial property values for an instance of
`MySqlCommand'.

* Properties*                        * Initial Value*
* `CommandText' *                    * empty string ("")*
* `CommandTimeout' *                 * 0*
* `CommandType' *                    * CommandType.Text*
* `Connection' *                     * Null*

You can change the value for any of these properties through a separate
call to the property.

*Examples*

The following example creates a `MySqlCommand' and sets some of its
properties.

Visual Basic example:

     Public Sub CreateMySqlCommand()
         Dim myCommand As New MySqlCommand()
         myCommand.CommandType = CommandType.Text
     End Sub

C# example:

     public void CreateMySqlCommand()
     {
        MySqlCommand myCommand = new MySqlCommand();
        myCommand.CommandType = CommandType.Text;
     }


File: manual.info,  Node: connector-net-examples-mysqlcommand-ctor2,  Next: connector-net-examples-mysqlcommand-ctor3,  Prev: connector-net-examples-mysqlcommand-ctor1,  Up: connector-net-examples-mysqlcommand

30.2.3.3 Class MySqlCommand Constructor Form 2
..............................................

Initializes a new instance of the `MySqlCommand' class with the text of
the query.

*Parameters:* The text of the query.

When an instance of `MySqlCommand' is created, the following read/write
properties are set to initial values.

* Properties*                        * Initial Value*
* `CommandText' *                    * `cmdText' *
* `CommandTimeout' *                 * 0*
* `CommandType' *                    * CommandType.Text*
* `Connection' *                     * Null*

You can change the value for any of these properties through a separate
call to the property.

*Examples*

The following example creates a `MySqlCommand' and sets some of its
properties.

Visual Basic example:

     Public Sub CreateMySqlCommand()
       Dim sql as String = "SELECT * FROM mytable"
         Dim myCommand As New MySqlCommand(sql)
         myCommand.CommandType = CommandType.Text
     End Sub

C# example:

     public void CreateMySqlCommand()
     {
       string sql = "SELECT * FROM mytable";
       MySqlCommand myCommand = new MySqlCommand(sql);
       myCommand.CommandType = CommandType.Text;
     }


File: manual.info,  Node: connector-net-examples-mysqlcommand-ctor3,  Next: connector-net-examples-mysqlcommand-ctor4,  Prev: connector-net-examples-mysqlcommand-ctor2,  Up: connector-net-examples-mysqlcommand

30.2.3.4 Class MySqlCommand Constructor Form 3
..............................................

Initializes a new instance of the `MySqlCommand' class with the text of
the query and a `MySqlConnection'.

*Parameters:* The text of the query.

*Parameters:* A `MySqlConnection' that represents the connection to an
instance of SQL Server.

When an instance of `MySqlCommand' is created, the following read/write
properties are set to initial values.

* Properties*                        * Initial Value*
* `CommandText' *                    * `cmdText' *
* `CommandTimeout' *                 * 0*
* `CommandType' *                    * CommandType.Text*
* `Connection' *                     * `connection' *

You can change the value for any of these properties through a separate
call to the property.

*Examples*

The following example creates a `MySqlCommand' and sets some of its
properties.

Visual Basic example:

     Public Sub CreateMySqlCommand()
       Dim conn as new MySqlConnection("server=myServer")
       Dim sql as String = "SELECT * FROM mytable"
         Dim myCommand As New MySqlCommand(sql, conn)
         myCommand.CommandType = CommandType.Text
     End Sub

C# example:

     public void CreateMySqlCommand()
     {
       MySqlConnection conn = new MySqlConnection("server=myserver")
       string sql = "SELECT * FROM mytable";
       MySqlCommand myCommand = new MySqlCommand(sql, conn);
       myCommand.CommandType = CommandType.Text;
     }


File: manual.info,  Node: connector-net-examples-mysqlcommand-ctor4,  Next: connector-net-examples-mysqlcommand-executenonquery,  Prev: connector-net-examples-mysqlcommand-ctor3,  Up: connector-net-examples-mysqlcommand

30.2.3.5 Class MySqlCommand Constructor Form 4
..............................................

Initializes a new instance of the `MySqlCommand' class with the text of
the query, a `MySqlConnection', and the `MySqlTransaction'.

*Parameters:* The text of the query.

*Parameters:* A `MySqlConnection' that represents the connection to an
instance of SQL Server.

*Parameters:* The `MySqlTransaction' in which the `MySqlCommand'
executes.

When an instance of `MySqlCommand' is created, the following read/write
properties are set to initial values.

* Properties*                        * Initial Value*
* `CommandText' *                    * `cmdText' *
* `CommandTimeout' *                 * 0*
* `CommandType' *                    * CommandType.Text*
* `Connection' *                     * `connection' *

You can change the value for any of these properties through a separate
call to the property.

*Examples*

The following example creates a `MySqlCommand' and sets some of its
properties.

Visual Basic example:

     Public Sub CreateMySqlCommand()
       Dim conn as new MySqlConnection("server=myServer")
       conn.Open();
       Dim txn as MySqlTransaction = conn.BeginTransaction()
       Dim sql as String = "SELECT * FROM mytable"
         Dim myCommand As New MySqlCommand(sql, conn, txn)
         myCommand.CommandType = CommandType.Text
     End Sub

C# example:

     public void CreateMySqlCommand()
     {
       MySqlConnection conn = new MySqlConnection("server=myserver")
       conn.Open();
       MySqlTransaction txn = conn.BeginTransaction();
       string sql = "SELECT * FROM mytable";
       MySqlCommand myCommand = new MySqlCommand(sql, conn, txn);
       myCommand.CommandType = CommandType.Text;
     }


File: manual.info,  Node: connector-net-examples-mysqlcommand-executenonquery,  Next: connector-net-examples-mysqlcommand-executereader1,  Prev: connector-net-examples-mysqlcommand-ctor4,  Up: connector-net-examples-mysqlcommand

30.2.3.6 ExecuteNonQuery
........................

Executes a SQL statement against the connection and returns the number
of rows affected.

*Returns:* Number of rows affected

You can use ExecuteNonQuery to perform any type of database operation,
however any resultsets returned will not be available. Any output
parameters used in calling a stored procedure will be populated with
data and can be retrieved after execution is complete. For UPDATE,
INSERT, and DELETE statements, the return value is the number of rows
affected by the command. For all other types of statements, the return
value is -1.

*Examples*

The following example creates a MySqlCommand and then executes it using
ExecuteNonQuery. The example is passed a string that is a SQL statement
(such as UPDATE, INSERT, or DELETE) and a string to use to connect to
the data source.

Visual Basic example:

         Public Sub CreateMySqlCommand(myExecuteQuery As String, myConnection As MySqlConnection)
           Dim myCommand As New MySqlCommand(myExecuteQuery, myConnection)
           myCommand.Connection.Open()
           myCommand.ExecuteNonQuery()
           myConnection.Close()
         End Sub

C# example:

         public void CreateMySqlCommand(string myExecuteQuery, MySqlConnection myConnection)
         {
           MySqlCommand myCommand = new MySqlCommand(myExecuteQuery, myConnection);
           myCommand.Connection.Open();
           myCommand.ExecuteNonQuery();
           myConnection.Close();
         }


File: manual.info,  Node: connector-net-examples-mysqlcommand-executereader1,  Next: connector-net-examples-mysqlcommand-executereader,  Prev: connector-net-examples-mysqlcommand-executenonquery,  Up: connector-net-examples-mysqlcommand

30.2.3.7 ExecuteReader1
.......................

Sends the `CommandText' to the `MySqlConnection'Connection, and builds a
`MySqlDataReader' using one of the `CommandBehavior' values.

*Parameters:* One of the `CommandBehavior' values.

When the `CommandType' property is set to `StoredProcedure', the
`CommandText' property should be set to the name of the stored
procedure. The command executes this stored procedure when you call
`ExecuteReader'.

The `MySqlDataReader' supports a special mode that enables large binary
values to be read efficiently. For more information, see the
`SequentialAccess' setting for `CommandBehavior'.

While the `MySqlDataReader' is in use, the associated `MySqlConnection'
is busy serving the `MySqlDataReader'. While in this state, no other
operations can be performed on the `MySqlConnection' other than closing
it. This is the case until the `MySqlDataReader.Close' method of the
`MySqlDataReader' is called. If the `MySqlDataReader' is created with
`CommandBehavior' set to `CloseConnection', closing the
`MySqlDataReader' closes the connection automatically.

*Note*:

When calling `ExecuteReader' with the `SingleRow' behavior, you should
be aware that using a `limit' clause in your SQL will cause all rows
(up to the limit given) to be retrieved by the client. The
`MySqlDataReader.Read' method will still return false after the first
row but pulling all rows of data into the client will have a
performance impact. If the `limit' clause is not necessary, it should
be avoided.

*Returns:* A `MySqlDataReader' object.


File: manual.info,  Node: connector-net-examples-mysqlcommand-executereader,  Next: connector-net-examples-mysqlcommand-prepare,  Prev: connector-net-examples-mysqlcommand-executereader1,  Up: connector-net-examples-mysqlcommand

30.2.3.8 Using `ExecuteReader'
..............................

Sends the `CommandText' to the `MySqlConnection'Connection and builds a
`MySqlDataReader'.

*Returns:* A `MySqlDataReader' object.

When the `CommandType' property is set to `StoredProcedure', the
`CommandText' property should be set to the name of the stored
procedure. The command executes this stored procedure when you call
`ExecuteReader'.

While the `MySqlDataReader' is in use, the associated `MySqlConnection'
is busy serving the `MySqlDataReader'. While in this state, no other
operations can be performed on the `MySqlConnection' other than closing
it. This is the case until the `MySqlDataReader.Close' method of the
`MySqlDataReader' is called.

*Examples*

The following example creates a `MySqlCommand', then executes it by
passing a string that is a SQL `SELECT' statement, and a string to use
to connect to the data source.

Visual Basic example:

     Public Sub CreateMySqlDataReader(mySelectQuery As String, myConnection As MySqlConnection)
         Dim myCommand As New MySqlCommand(mySelectQuery, myConnection)
         myConnection.Open()
         Dim myReader As MySqlDataReader
         myReader = myCommand.ExecuteReader()
         Try
         While myReader.Read()
             Console.WriteLine(myReader.GetString(0))
         End While
     Finally
         myReader.Close
         myConnection.Close
         End Try
     End Sub

C# example:

     public void CreateMySqlDataReader(string mySelectQuery, MySqlConnection myConnection)
      {
         MySqlCommand myCommand = new MySqlCommand(mySelectQuery, myConnection);
         myConnection.Open();
         MySqlDataReader myReader;
         myReader = myCommand.ExecuteReader();
         try
         {
           while(myReader.Read())
           {
             Console.WriteLine(myReader.GetString(0));
           }
         }
         finally
         {
           myReader.Close();
           myConnection.Close();
         }
      }


File: manual.info,  Node: connector-net-examples-mysqlcommand-prepare,  Next: connector-net-examples-mysqlcommand-executescalar,  Prev: connector-net-examples-mysqlcommand-executereader,  Up: connector-net-examples-mysqlcommand

30.2.3.9 Using `Prepare'
........................

Creates a prepared version of the command on an instance of MySQL
Server.

Prepared statements are only supported on MySQL version 4.1 and higher.
Calling prepare while connected to earlier versions of MySQL will
succeed but will execute the statement in the same way as unprepared.

*Examples*

The following example demonstrates the use of the `Prepare' method.

Visual Basic example:

       public sub PrepareExample()
         Dim cmd as New MySqlCommand("INSERT INTO mytable VALUES (?val)", myConnection)
         cmd.Parameters.Add( "?val", 10 )
         cmd.Prepare()
         cmd.ExecuteNonQuery()

         cmd.Parameters(0).Value = 20
         cmd.ExecuteNonQuery()
       end sub

C# example:

       private void PrepareExample()
       {
         MySqlCommand cmd = new MySqlCommand("INSERT INTO mytable VALUES (@val)", myConnection);
         cmd.Parameters.Add( "@val", 10 );
         cmd.Prepare();
         cmd.ExecuteNonQuery();

         cmd.Parameters[0].Value = 20;
         cmd.ExecuteNonQuery();
       }


File: manual.info,  Node: connector-net-examples-mysqlcommand-executescalar,  Next: connector-net-examples-mysqlcommand-commandtext,  Prev: connector-net-examples-mysqlcommand-prepare,  Up: connector-net-examples-mysqlcommand

30.2.3.10 ExecuteScalar
.......................

Executes the query, and returns the first column of the first row in
the result set returned by the query. Extra columns or rows are ignored.

*Returns:* The first column of the first row in the result set, or a
null reference if the result set is empty

Use the `ExecuteScalar' method to retrieve a single value (for example,
an aggregate value) from a database. This requires less code than using
the `ExecuteReader' method, and then performing the operations
necessary to generate the single value using the data returned by a
`MySqlDataReader'

A typical `ExecuteScalar' query can be formatted as in the following C#
example:

C# example:

     cmd.CommandText = "select count(*) from region";
     Int32 count = (int32) cmd.ExecuteScalar();

*Examples*

The following example creates a `MySqlCommand' and then executes it
using `ExecuteScalar'. The example is passed a string that is a SQL
statement that returns an aggregate result, and a string to use to
connect to the data source.

Visual Basic example:

     Public Sub CreateMySqlCommand(myScalarQuery As String, myConnection As MySqlConnection)
         Dim myCommand As New MySqlCommand(myScalarQuery, myConnection)
         myCommand.Connection.Open()
         myCommand.ExecuteScalar()
         myConnection.Close()
     End Sub

C# example:

     public void CreateMySqlCommand(string myScalarQuery, MySqlConnection myConnection)
      {
         MySqlCommand myCommand = new MySqlCommand(myScalarQuery, myConnection);
         myCommand.Connection.Open();
         myCommand.ExecuteScalar();
         myConnection.Close();
      }

C++ example:

     public:
         void CreateMySqlCommand(String* myScalarQuery, MySqlConnection* myConnection)
         {
             MySqlCommand* myCommand = new MySqlCommand(myScalarQuery, myConnection);
             myCommand->Connection->Open();
             myCommand->ExecuteScalar();
             myConnection->Close();
         }


File: manual.info,  Node: connector-net-examples-mysqlcommand-commandtext,  Next: connector-net-examples-mysqlcommand-commandtimeout,  Prev: connector-net-examples-mysqlcommand-executescalar,  Up: connector-net-examples-mysqlcommand

30.2.3.11 CommandText
.....................

Gets or sets the SQL statement to execute at the data source.

*Value:* The SQL statement or stored procedure to execute. The default
is an empty string.

When the `CommandType' property is set to `StoredProcedure', the
`CommandText' property should be set to the name of the stored
procedure. The user may be required to use escape character syntax if
the stored procedure name contains any special characters. The command
executes this stored procedure when you call one of the Execute methods.

*Examples*

The following example creates a `MySqlCommand' and sets some of its
properties.

Visual Basic example:

     Public Sub CreateMySqlCommand()
         Dim myCommand As New MySqlCommand()
         myCommand.CommandText = "SELECT * FROM Mytable ORDER BY id"
         myCommand.CommandType = CommandType.Text
     End Sub

C# example:

     public void CreateMySqlCommand()
      {
         MySqlCommand myCommand = new MySqlCommand();
         myCommand.CommandText = "SELECT * FROM mytable ORDER BY id";
         myCommand.CommandType = CommandType.Text;
      }


File: manual.info,  Node: connector-net-examples-mysqlcommand-commandtimeout,  Next: connector-net-examples-mysqlcommand-commandtype,  Prev: connector-net-examples-mysqlcommand-commandtext,  Up: connector-net-examples-mysqlcommand

30.2.3.12 CommandTimeout
........................

Gets or sets the wait time before terminating the attempt to execute a
command and generating an error.

*Value:* The time (in seconds) to wait for the command to execute. The
default is 0 seconds.

MySQL currently does not support any method of canceling a pending or
executing operation. All commands issued against a MySQL server will
execute until completion or until an exception occurs.

MySQL Enterprise

MySQL Enterprise subscribers will find more information about
CommandTimeout in the Knowledge Base article, Why CommandTimeout is not
Supported (https://kb.mysql.com/view.php?id=4920). Access to the MySQL
Knowledge Base collection of articles is one of the advantages of
subscribing to MySQL Enterprise. For more information see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: connector-net-examples-mysqlcommand-commandtype,  Next: connector-net-examples-mysqlcommand-connection,  Prev: connector-net-examples-mysqlcommand-commandtimeout,  Up: connector-net-examples-mysqlcommand

30.2.3.13 CommandType
.....................

Gets or sets a value indicating how the `CommandText' property is to be
interpreted.

*Value:* One of the `System.Data.CommandType' values. The default is
`Text'.

When you set the `CommandType' property to `StoredProcedure', you
should set the `CommandText' property to the name of the stored
procedure. The command executes this stored procedure when you call one
of the Execute methods.

*Examples*

The following example creates a `MySqlCommand' and sets some of its
properties.

Visual Basic example:

     Public Sub CreateMySqlCommand()
         Dim myCommand As New MySqlCommand()
         myCommand.CommandType = CommandType.Text
     End Sub

C# example:

     public void CreateMySqlCommand()
     {
        MySqlCommand myCommand = new MySqlCommand();
        myCommand.CommandType = CommandType.Text;
     }


File: manual.info,  Node: connector-net-examples-mysqlcommand-connection,  Next: connector-net-examples-mysqlcommand-isprepared,  Prev: connector-net-examples-mysqlcommand-commandtype,  Up: connector-net-examples-mysqlcommand

30.2.3.14 Connection
....................

Gets or sets the `MySqlConnection' used by this instance of the
`MySqlCommand'.

*Value:* The connection to a data source. The default value is a null
reference (`Nothing' in Visual Basic).

If you set `Connection' while a transaction is in progress and the
`Transaction' property is not null, an `InvalidOperationException' is
generated. If the `Transaction' property is not null and the
transaction has already been committed or rolled back, `Transaction' is
set to null.

*Examples*

The following example creates a `MySqlCommand' and sets some of its
properties.

Visual Basic example:

     Public Sub CreateMySqlCommand()
         Dim mySelectQuery As String = "SELECT * FROM mytable ORDER BY id"
         Dim myConnectString As String = "Persist Security Info=False;database=test;server=myServer"
         Dim myCommand As New MySqlCommand(mySelectQuery)
         myCommand.Connection = New MySqlConnection(myConnectString)
         myCommand.CommandType = CommandType.Text
     End Sub

C# example:

     public void CreateMySqlCommand()
      {
         string mySelectQuery = "SELECT * FROM mytable ORDER BY id";
         string myConnectString = "Persist Security Info=False;database=test;server=myServer";
         MySqlCommand myCommand = new MySqlCommand(mySelectQuery);
         myCommand.Connection = new MySqlConnection(myConnectString);
         myCommand.CommandType = CommandType.Text;
      }


File: manual.info,  Node: connector-net-examples-mysqlcommand-isprepared,  Next: connector-net-examples-mysqlcommand-parameters,  Prev: connector-net-examples-mysqlcommand-connection,  Up: connector-net-examples-mysqlcommand

30.2.3.15 IsPrepared
....................

Returns true if the statement is prepared.


File: manual.info,  Node: connector-net-examples-mysqlcommand-parameters,  Next: connector-net-examples-mysqlcommand-transaction,  Prev: connector-net-examples-mysqlcommand-isprepared,  Up: connector-net-examples-mysqlcommand

30.2.3.16 Parameters
....................

Get the `MySqlParameterCollection'

*Value:* The parameters of the SQL statement or stored procedure. The
default is an empty collection.

Connector/Net does not support unnamed parameters. Every parameter
added to the collection must have an associated name.

*Examples*

The following example creates a `MySqlCommand' and displays its
parameters.  To accomplish this, the method is passed a
`MySqlConnection', a query string that is a SQL `SELECT' statement, and
an array of `MySqlParameter' objects.

Visual Basic example:

     Public Sub CreateMySqlCommand(myConnection As MySqlConnection, _
     mySelectQuery As String, myParamArray() As MySqlParameter)
         Dim myCommand As New MySqlCommand(mySelectQuery, myConnection)
         myCommand.CommandText = "SELECT id, name FROM mytable WHERE age=@age"
         myCommand.UpdatedRowSource = UpdateRowSource.Both
         myCommand.Parameters.Add(myParamArray)
         Dim j As Integer
         For j = 0 To myCommand.Parameters.Count - 1
            myCommand.Parameters.Add(myParamArray(j))
         Next j
         Dim myMessage As String = ""
         Dim i As Integer
         For i = 0 To myCommand.Parameters.Count - 1
             myMessage += myCommand.Parameters(i).ToString() & ControlChars.Cr
         Next i
         Console.WriteLine(myMessage)
     End Sub

C# example:

     public void CreateMySqlCommand(MySqlConnection myConnection, string mySelectQuery,
       MySqlParameter[] myParamArray)
     {
        MySqlCommand myCommand = new MySqlCommand(mySelectQuery, myConnection);
        myCommand.CommandText = "SELECT id, name FROM mytable WHERE age=@age";
        myCommand.Parameters.Add(myParamArray);
        for (int j=0; j<myParamArray.Length; j++)
        {
           myCommand.Parameters.Add(myParamArray[j]) ;
        }
        string myMessage = "";
        for (int i = 0; i < myCommand.Parameters.Count; i++)
        {
           myMessage += myCommand.Parameters[i].ToString() + "\n";
        }
        MessageBox.Show(myMessage);
     }


File: manual.info,  Node: connector-net-examples-mysqlcommand-transaction,  Next: connector-net-examples-mysqlcommand-updatedrowsource,  Prev: connector-net-examples-mysqlcommand-parameters,  Up: connector-net-examples-mysqlcommand

30.2.3.17 Transaction
.....................

Gets or sets the `MySqlTransaction' within which the `MySqlCommand'
executes.

*Value:* The `MySqlTransaction'. The default value is a null reference
(`Nothing' in Visual Basic).

You cannot set the `Transaction' property if it is already set to a
specific value, and the command is in the process of executing. If you
set the transaction property to a `MySqlTransaction' object that is not
connected to the same `MySqlConnection' as the `MySqlCommand' object,
an exception will be thrown the next time you attempt to execute a
statement.


File: manual.info,  Node: connector-net-examples-mysqlcommand-updatedrowsource,  Prev: connector-net-examples-mysqlcommand-transaction,  Up: connector-net-examples-mysqlcommand

30.2.3.18 UpdatedRowSource
..........................

Gets or sets how command results are applied to the `DataRow' when used
by the `System.Data.Common.DbDataAdapter.Update' method of the
`System.Data.Common.DbDataAdapter'.

*Value:* One of the `UpdateRowSource' values.

The default `System.Data.UpdateRowSource' value is `Both' unless the
command is automatically generated (as in the case of the
`MySqlCommandBuilder'), in which case the default is `None'.


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder,  Next: connector-net-examples-mysqlconnection,  Prev: connector-net-examples-mysqlcommand,  Up: connector-net-examples

30.2.3.19 Using `MySqlCommandBuilder'
.....................................

* Menu:

* connector-net-examples-mysqlcommandbuilder-ctor::  Class MySqlCommandBuilder Constructor
* connector-net-examples-mysqlcommandbuilder-ctor1::  Class MySqlCommandBuilder Constructor Form 1
* connector-net-examples-mysqlcommandbuilder-ctor2::  Class MySqlCommandBuilder Constructor Form 2
* connector-net-examples-mysqlcommandbuilder-ctor3::  Class MySqlCommandBuilder Constructor Form 3
* connector-net-examples-mysqlcommandbuilder-dataadapter::  DataAdapter
* connector-net-examples-mysqlcommandbuilder-quoteprefix::  QuotePrefix
* connector-net-examples-mysqlcommandbuilder-quotesuffix::  QuoteSuffix
* connector-net-examples-mysqlcommandbuilder-deriveparameters::  DeriveParameters
* connector-net-examples-mysqlcommandbuilder-getdeletecommand::  GetDeleteCommand
* connector-net-examples-mysqlcommandbuilder-getinsertcommand::  GetInsertCommand
* connector-net-examples-mysqlcommandbuilder-getupdatecommand::  GetUpdateCommand
* connector-net-examples-mysqlcommandbuilder-refreshschema::  RefreshSchema

Automatically generates single-table commands used to reconcile changes
made to a DataSet with the associated MySQL database.  This class
cannot be inherited.

The `MySqlDataAdapter' does not automatically generate the SQL
statements required to reconcile changes made to a
`System.Data.DataSet'DataSet with the associated instance of MySQL.
However, you can create a `MySqlCommandBuilder' object to automatically
generate SQL statements for single-table updates if you set the
`MySqlDataAdapter.SelectCommand'SelectCommand property of the
`MySqlDataAdapter'. Then, any additional SQL statements that you do not
set are generated by the `MySqlCommandBuilder'.

The `MySqlCommandBuilder' registers itself as a listener for
`MySqlDataAdapter.OnRowUpdating'RowUpdating events whenever you set the
`DataAdapter' property. You can only associate one `MySqlDataAdapter' or
`MySqlCommandBuilder' object with each other at one time.

To generate INSERT, UPDATE, or DELETE statements, the
`MySqlCommandBuilder' uses the `SelectCommand' property to retrieve a
required set of metadata automatically. If you change the
`SelectCommand' after the metadata has is retrieved (for example, after
the first update), you should call the `RefreshSchema' method to update
the metadata.

The `SelectCommand' must also return at least one primary key or unique
column. If none are present, an `InvalidOperation' exception is
generated, and the commands are not generated.

When using `MySqlCommandbuilder' and `INSERT' you should set the
`ReturnGeneratedIdentifiers' property to `true' to ensure that
`AUTO_INCREMENT' fields in MySQL tables return the automatically
generated value.

The `MySqlCommandBuilder' also uses the
`MySqlCommand.Connection'Connection,
`MySqlCommand.CommandTimeout'CommandTimeout, and
`MySqlCommand.Transaction'Transaction properties referenced by the
`SelectCommand'.  The user should call `RefreshSchema' if any of these
properties are modified, or if the `SelectCommand' itself is replaced.
Otherwise the `MySqlDataAdapter.InsertCommand'InsertCommand,
`MySqlDataAdapter.UpdateCommand'UpdateCommand, and
`MySqlDataAdapter.DeleteCommand'DeleteCommand properties retain their
previous values.

If you call `Dispose', the `MySqlCommandBuilder' is disassociated from
the `MySqlDataAdapter', and the generated commands are no longer used.

*Note*:

Caution must be used when using `MySqlCommandBuilder' on MySql 4.0
systems.  With MySQL 4.0, database/schema information is not provided to
the connector for a query. This means that a query that pulls columns
from two identically named tables in two or more different databases
will not cause an exception to be thrown but will not work correctly.
Even more dangerous is the situation where your select statement
references database X but is executed in database Y and both databases
have tables with similar layouts. This situation can cause unwanted
changes or deletes. This note does not apply to MySQL versions 4.1 and
later.

*Examples*

The following example uses the `MySqlCommand', along `MySqlDataAdapter'
and `MySqlConnection', to select rows from a data source. The example
is passed an initialized `System.Data.DataSet', a connection string, a
query string that is a SQL `SELECT' statement, and a string that is the
name of the database table. The example then creates a
`MySqlCommandBuilder'.

Visual Basic example:

       Public Shared Function SelectRows(myConnection As String, mySelectQuery As String, myTableName As String) As DataSet
         Dim myConn As New MySqlConnection(myConnection)
         Dim myDataAdapter As New MySqlDataAdapter()
         myDataAdapter.SelectCommand = New MySqlCommand(mySelectQuery, myConn)
         Dim cb As SqlCommandBuilder = New MySqlCommandBuilder(myDataAdapter)
         myConn.Open()
         Dim ds As DataSet = New DataSet
         myDataAdapter.Fill(ds, myTableName)
         ' Code to modify data in DataSet here
         ' Without the MySqlCommandBuilder this line would fail.
         myDataAdapter.Update(ds, myTableName)
         myConn.Close()
       End Function 'SelectRows

C# example:

       public static DataSet SelectRows(string myConnection, string mySelectQuery, string myTableName)
       {
       MySqlConnection myConn = new MySqlConnection(myConnection);
       MySqlDataAdapter myDataAdapter = new MySqlDataAdapter();
       myDataAdapter.SelectCommand = new MySqlCommand(mySelectQuery, myConn);
       MySqlCommandBuilder cb = new MySqlCommandBuilder(myDataAdapter);
       myConn.Open();
       DataSet ds = new DataSet();
       myDataAdapter.Fill(ds, myTableName);
       //code to modify data in DataSet here
       //Without the MySqlCommandBuilder this line would fail
       myDataAdapter.Update(ds, myTableName);
       myConn.Close();
       return ds;
       }


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder-ctor,  Next: connector-net-examples-mysqlcommandbuilder-ctor1,  Prev: connector-net-examples-mysqlcommandbuilder,  Up: connector-net-examples-mysqlcommandbuilder

30.2.3.20 Class MySqlCommandBuilder Constructor
...............................................

Initializes a new instance of the `MySqlCommandBuilder' class.


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder-ctor1,  Next: connector-net-examples-mysqlcommandbuilder-ctor2,  Prev: connector-net-examples-mysqlcommandbuilder-ctor,  Up: connector-net-examples-mysqlcommandbuilder

30.2.3.21 Class MySqlCommandBuilder Constructor Form 1
......................................................

Initializes a new instance of the `MySqlCommandBuilder' class and sets
the last one wins property.

*Parameters:* False to generate change protection code. True otherwise.

The `lastOneWins' parameter indicates whether SQL code should be
included with the generated DELETE and UPDATE commands that checks the
underlying data for changes.  If `lastOneWins' is true then this code is
not included and data records could be overwritten in a multi-user or
multi-threaded environments. Setting `lastOneWins' to false will
include this check which will cause a concurrency exception to be
thrown if the underlying data record has changed without our knowledge.


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder-ctor2,  Next: connector-net-examples-mysqlcommandbuilder-ctor3,  Prev: connector-net-examples-mysqlcommandbuilder-ctor1,  Up: connector-net-examples-mysqlcommandbuilder

30.2.3.22 Class MySqlCommandBuilder Constructor Form 2
......................................................

Initializes a new instance of the `MySqlCommandBuilder' class with the
associated `MySqlDataAdapter' object.

*Parameters:* The `MySqlDataAdapter' to use.

The `MySqlCommandBuilder' registers itself as a listener for
`MySqlDataAdapter.RowUpdating' events that are generated by the
`MySqlDataAdapter' specified in this property.

When you create a new instance `MySqlCommandBuilder', any existing
`MySqlCommandBuilder' associated with this `MySqlDataAdapter' is
released.


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder-ctor3,  Next: connector-net-examples-mysqlcommandbuilder-dataadapter,  Prev: connector-net-examples-mysqlcommandbuilder-ctor2,  Up: connector-net-examples-mysqlcommandbuilder

30.2.3.23 Class MySqlCommandBuilder Constructor Form 3
......................................................

Initializes a new instance of the `MySqlCommandBuilder' class with the
associated `MySqlDataAdapter' object.

*Parameters:* The `MySqlDataAdapter' to use.

*Parameters:* False to generate change protection code. True otherwise.

The `MySqlCommandBuilder' registers itself as a listener for
`MySqlDataAdapter.RowUpdating' events that are generated by the
`MySqlDataAdapter' specified in this property.

When you create a new instance `MySqlCommandBuilder', any existing
`MySqlCommandBuilder' associated with this `MySqlDataAdapter' is
released.

The `lastOneWins' parameter indicates whether SQL code should be
included with the generated DELETE and UPDATE commands that checks the
underlying data for changes.  If `lastOneWins' is true then this code is
not included and data records could be overwritten in a multi-user or
multi-threaded environments. Setting `lastOneWins' to false will
include this check which will cause a concurrency exception to be
thrown if the underlying data record has changed without our knowledge.


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder-dataadapter,  Next: connector-net-examples-mysqlcommandbuilder-quoteprefix,  Prev: connector-net-examples-mysqlcommandbuilder-ctor3,  Up: connector-net-examples-mysqlcommandbuilder

30.2.3.24 DataAdapter
.....................

Gets or sets a `MySqlDataAdapter' object for which SQL statements are
automatically generated.

*Value:* A `MySqlDataAdapter' object.

The `MySqlCommandBuilder' registers itself as a listener for
`MySqlDataAdapter.RowUpdating' events that are generated by the
`MySqlDataAdapter' specified in this property.

When you create a new instance `MySqlCommandBuilder', any existing
`MySqlCommandBuilder' associated with this `MySqlDataAdapter' is
released.


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder-quoteprefix,  Next: connector-net-examples-mysqlcommandbuilder-quotesuffix,  Prev: connector-net-examples-mysqlcommandbuilder-dataadapter,  Up: connector-net-examples-mysqlcommandbuilder

30.2.3.25 QuotePrefix
.....................

Gets or sets the beginning character or characters to use when
specifying MySQL database objects (for example, tables or columns)
whose names contain characters such as spaces or reserved tokens.

*Value:* The beginning character or characters to use. The default
value is `.

Database objects in MySQL can contain special characters such as spaces
that would make normal SQL strings impossible to correctly parse. Use
of the `QuotePrefix' and the `QuoteSuffix' properties allows the
`MySqlCommandBuilder' to build SQL statements that handle this
situation.


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder-quotesuffix,  Next: connector-net-examples-mysqlcommandbuilder-deriveparameters,  Prev: connector-net-examples-mysqlcommandbuilder-quoteprefix,  Up: connector-net-examples-mysqlcommandbuilder

30.2.3.26 QuoteSuffix
.....................

Gets or sets the beginning character or characters to use when
specifying MySQL database objects (for example, tables or columns)
whose names contain characters such as spaces or reserved tokens.

*Value:* The beginning character or characters to use. The default
value is `.

Database objects in MySQL can contain special characters such as spaces
that would make normal SQL strings impossible to correctly parse. Use
of the `QuotePrefix' and the `QuoteSuffix' properties allows the
`MySqlCommandBuilder' to build SQL statements that handle this
situation.


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder-deriveparameters,  Next: connector-net-examples-mysqlcommandbuilder-getdeletecommand,  Prev: connector-net-examples-mysqlcommandbuilder-quotesuffix,  Up: connector-net-examples-mysqlcommandbuilder

30.2.3.27 DeriveParameters
..........................


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder-getdeletecommand,  Next: connector-net-examples-mysqlcommandbuilder-getinsertcommand,  Prev: connector-net-examples-mysqlcommandbuilder-deriveparameters,  Up: connector-net-examples-mysqlcommandbuilder

30.2.3.28 GetDeleteCommand
..........................

Gets the automatically generated `MySqlCommand' object required to
perform deletions on the database.

*Returns:* The `MySqlCommand' object generated to handle delete
operations.

An application can use the `GetDeleteCommand' method for informational
or troubleshooting purposes because it returns the `MySqlCommand'
object to be executed.

You can also use `GetDeleteCommand' as the basis of a modified command.
For example, you might call `GetDeleteCommand' and modify the
`MySqlCommand.CommandTimeout' value, and then explicitly set that on the
`MySqlDataAdapter'.

After the SQL statement is first generated, the application must
explicitly call `RefreshSchema' if it changes the statement in any way.
Otherwise, the `GetDeleteCommand' will be still be using information
from the previous statement, which might not be correct. The SQL
statements are first generated either when the application calls
`System.Data.Common.DataAdapter.Update' or `GetDeleteCommand'.


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder-getinsertcommand,  Next: connector-net-examples-mysqlcommandbuilder-getupdatecommand,  Prev: connector-net-examples-mysqlcommandbuilder-getdeletecommand,  Up: connector-net-examples-mysqlcommandbuilder

30.2.3.29 GetInsertCommand
..........................

Gets the automatically generated `MySqlCommand' object required to
perform insertions on the database.

*Returns:* The `MySqlCommand' object generated to handle insert
operations.

An application can use the `GetInsertCommand' method for informational
or troubleshooting purposes because it returns the `MySqlCommand'
object to be executed.

You can also use the `GetInsertCommand' as the basis of a modified
command. For example, you might call `GetInsertCommand' and modify the
`MySqlCommand.CommandTimeout' value, and then explicitly set that on the
`MySqlDataAdapter'.

After the SQL statement is first generated, the application must
explicitly call `RefreshSchema' if it changes the statement in any way.
Otherwise, the `GetInsertCommand' will be still be using information
from the previous statement, which might not be correct. The SQL
statements are first generated either when the application calls
`System.Data.Common.DataAdapter.Update' or `GetInsertCommand'.


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder-getupdatecommand,  Next: connector-net-examples-mysqlcommandbuilder-refreshschema,  Prev: connector-net-examples-mysqlcommandbuilder-getinsertcommand,  Up: connector-net-examples-mysqlcommandbuilder

30.2.3.30 GetUpdateCommand
..........................

Gets the automatically generated `MySqlCommand' object required to
perform updates on the database.

*Returns:* The `MySqlCommand' object generated to handle update
operations.

An application can use the `GetUpdateCommand' method for informational
or troubleshooting purposes because it returns the `MySqlCommand'
object to be executed.

You can also use `GetUpdateCommand' as the basis of a modified command.
For example, you might call `GetUpdateCommand' and modify the
`MySqlCommand.CommandTimeout' value, and then explicitly set that on the
`MySqlDataAdapter'.

After the SQL statement is first generated, the application must
explicitly call `RefreshSchema' if it changes the statement in any way.
Otherwise, the `GetUpdateCommand' will be still be using information
from the previous statement, which might not be correct. The SQL
statements are first generated either when the application calls
`System.Data.Common.DataAdapter.Update' or `GetUpdateCommand'.


File: manual.info,  Node: connector-net-examples-mysqlcommandbuilder-refreshschema,  Prev: connector-net-examples-mysqlcommandbuilder-getupdatecommand,  Up: connector-net-examples-mysqlcommandbuilder

30.2.3.31 RefreshSchema
.......................

Refreshes the database schema information used to generate INSERT,
UPDATE, or DELETE statements.

An application should call `RefreshSchema' whenever the `SELECT'
statement associated with the `MySqlCommandBuilder' changes.

An application should call `RefreshSchema' whenever the
`MySqlDataAdapter.SelectCommand' value of the `MySqlDataAdapter'
changes.

MySQL Enterprise

MySQL Enterprise subscribers will find more information on this topic
in the Knowledge Base article, Understanding MySqlCommandBuilder and
the LastOneWins Setting (https://kb.mysql.com/view.php?id=4922). For
information about subscribing to MySQL Enterprise see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: connector-net-examples-mysqlconnection,  Next: connector-net-examples-mysqldataadapter,  Prev: connector-net-examples-mysqlcommandbuilder,  Up: connector-net-examples

30.2.3.32 Using `MySqlConnection'
.................................

* Menu:

* connector-net-examples-mysqlconnection-defctor::  Class MySqlConnection Constructor (Default)
* connector-net-examples-mysqlconnection-ctor1::  Class MySqlConnection Constructor Form 1
* connector-net-examples-mysqlconnection-connectionstring::  ConnectionString
* connector-net-examples-mysqlconnection-open::  Open
* connector-net-examples-mysqlconnection-database::  Database
* connector-net-examples-mysqlconnection-state::  State
* connector-net-examples-mysqlconnection-serverversion::  ServerVersion
* connector-net-examples-mysqlconnection-close::  Close
* connector-net-examples-mysqlconnection-createcommand::  CreateCommand
* connector-net-examples-mysqlconnection-begintransaction::  BeginTransaction
* connector-net-examples-mysqlconnection-begintransaction1::  BeginTransaction1
* connector-net-examples-mysqlconnection-changedatabase::  ChangeDatabase
* connector-net-examples-mysqlconnection-statechange::  StateChange
* connector-net-examples-mysqlconnection-infomessage::  InfoMessage
* connector-net-examples-mysqlconnection-connectiontimeout::  ConnectionTimeout

Represents an open connection to a MySQL Server database. This class
cannot be inherited.

A `MySqlConnection' object represents a session to a MySQL Server data
source. When you create an instance of `MySqlConnection', all
properties are set to their initial values. For a list of these values,
see the `MySqlConnection' constructor.

If the `MySqlConnection' goes out of scope, it is not closed.
Therefore, you must explicitly close the connection by calling
`MySqlConnection.Close' or `MySqlConnection.Dispose'.

*Examples*

The following example creates a `MySqlCommand' and a `MySqlConnection'.
The `MySqlConnection' is opened and set as the
`MySqlCommand.Connection' for the `MySqlCommand'. The example then calls
`MySqlCommand.ExecuteNonQuery', and closes the connection. To
accomplish this, the `ExecuteNonQuery' is passed a connection string
and a query string that is a SQL INSERT statement.

Visual Basic example:

       Public Sub InsertRow(myConnectionString As String)
         ' If the connection string is null, use a default.
         If myConnectionString = "" Then
           myConnectionString = "Database=Test;Data Source=localhost;User Id=username;Password=pass"
         End If
         Dim myConnection As New MySqlConnection(myConnectionString)
         Dim myInsertQuery As String = "INSERT INTO Orders (id, customerId, amount) Values(1001, 23, 30.66)"
         Dim myCommand As New MySqlCommand(myInsertQuery)
         myCommand.Connection = myConnection
         myConnection.Open()
         myCommand.ExecuteNonQuery()
         myCommand.Connection.Close()
       End Sub

C# example:

       public void InsertRow(string myConnectionString)
       {
         // If the connection string is null, use a default.
         if(myConnectionString == "")
         {
           myConnectionString = "Database=Test;Data Source=localhost;User Id=username;Password=pass";
         }
         MySqlConnection myConnection = new MySqlConnection(myConnectionString);
         string myInsertQuery = "INSERT INTO Orders (id, customerId, amount) Values(1001, 23, 30.66)";
         MySqlCommand myCommand = new MySqlCommand(myInsertQuery);
         myCommand.Connection = myConnection;
         myConnection.Open();
         myCommand.ExecuteNonQuery();
         myCommand.Connection.Close();
       }


File: manual.info,  Node: connector-net-examples-mysqlconnection-defctor,  Next: connector-net-examples-mysqlconnection-ctor1,  Prev: connector-net-examples-mysqlconnection,  Up: connector-net-examples-mysqlconnection

30.2.3.33 Class MySqlConnection Constructor (Default)
.....................................................

Initializes a new instance of the `MySqlConnection' class.

When a new instance of `MySqlConnection' is created, the read/write
properties are set to the following initial values unless they are
specifically set using their associated keywords in the
`ConnectionString' property.

* Properties*                        * Initial Value*
* `ConnectionString' *               * empty string ("")*
* `ConnectionTimeout' *              * 15*
* `Database' *                       * empty string ("")*
* `DataSource' *                     * empty string ("")*
* `ServerVersion' *                  * empty string ("")*

You can change the value for these properties only by using the
`ConnectionString' property.

*Examples*

*Overload methods for MySqlConnection*

Initializes a new instance of the `MySqlConnection' class.


File: manual.info,  Node: connector-net-examples-mysqlconnection-ctor1,  Next: connector-net-examples-mysqlconnection-connectionstring,  Prev: connector-net-examples-mysqlconnection-defctor,  Up: connector-net-examples-mysqlconnection

30.2.3.34 Class MySqlConnection Constructor Form 1
..................................................

Initializes a new instance of the `MySqlConnection' class when given a
string containing the connection string.

When a new instance of `MySqlConnection' is created, the read/write
properties are set to the following initial values unless they are
specifically set using their associated keywords in the
`ConnectionString' property.

* Properties*                        * Initial Value*
* `ConnectionString' *               * empty string ("")*
* `ConnectionTimeout' *              * 15*
* `Database' *                       * empty string ("")*
* `DataSource' *                     * empty string ("")*
* `ServerVersion' *                  * empty string ("")*

You can change the value for these properties only by using the
`ConnectionString' property.

*Examples*

*Parameters:* The connection properties used to open the MySQL database.


File: manual.info,  Node: connector-net-examples-mysqlconnection-connectionstring,  Next: connector-net-examples-mysqlconnection-open,  Prev: connector-net-examples-mysqlconnection-ctor1,  Up: connector-net-examples-mysqlconnection

30.2.3.35 ConnectionString
..........................

Gets or sets the string used to connect to a MySQL Server database.

The `ConnectionString' returned may not be exactly like what was
originally set but will be indentical in terms of keyword/value pairs.
Security information will not be included unless the Persist Security
Info value is set to true.

You can use the `ConnectionString' property to connect to a database.
The following example illustrates a typical connection string.

     "Persist Security Info=False;database=MyDB;»
         server=MySqlServer;user id=myUser;Password=myPass"

The `ConnectionString' property can be set only when the connection is
closed. Many of the connection string values have corresponding
read-only properties. When the connection string is set, all of these
properties are updated, except when an error is detected. In this case,
none of the properties are updated.  `MySqlConnection' properties
return only those settings contained in the `ConnectionString'.

To connect to a local machine, specify "localhost" for the server. If
you do not specify a server, localhost is assumed.

Resetting the `ConnectionString' on a closed connection resets all
connection string values (and related properties) including the
password. For example, if you set a connection string that includes
"Database= MyDb", and then reset the connection string to "Data
Source=myserver;User Id=myUser;Password=myPass", the
`MySqlConnection.Database' property is no longer set to MyDb.

The connection string is parsed immediately after being set.  If errors
in syntax are found when parsing, a runtime exception, such as
`ArgumentException', is generated. Other errors can be found only when
an attempt is made to open the connection.

The basic format of a connection string consists of a series of
keyword/value pairs separated by semicolons. The equal sign (`=')
connects each keyword and its value.  Additional notes on setting
values for options:

   * To include values that contain a semicolon, single-quote
     character, or double-quote character, the value must be enclosed
     in double quotes. If the value contains both a semicolon and a
     double-quote character, the value can be enclosed in single
     quotes. The single quote is also useful if the value begins with a
     double-quote character.  Conversely, the double quote can be used
     if the value begins with a single quote. If the value contains both
     single-quote and double-quote characters, the quote character used
     to enclose the value must be doubled each time it occurs within
     the value.

   * To include preceding or trailing spaces in the string value, the
     value must be enclosed in either single quotes or double quotes.
     Any leading or trailing spaces around integer, Boolean, or
     enumerated values are ignored, even if enclosed in quotes.
     However, spaces within a string literal keyword or value are
     preserved. Using .NET Framework version 1.1, single or double
     quotes may be used within a connection string without using
     delimiters (for example, Data Source= my'Server or Data Source=
     my"Server), unless a quote character is the first or last
     character in the value.

   * To include an equal sign (=) in a keyword or value, it must be
     preceded by another equal sign. For example, in the hypothetical
     connection string

          "key==word=value"

     the keyword is "key=word" and the value is "value".

   * If a specific keyword in a keyword= value pair occurs multiple
     times in a connection string, the last occurrence listed is used
     in the value set.

   * Keywords are not case sensitive.

The following table lists the valid names for keyword values within the
`ConnectionString'.

Name                      Default Description
`Connect Timeout',        15      The length of time (in seconds) to wait
`Connection Timeout'              for a connection to the server before
                                  terminating the attempt and generating
                                  an error.
`Host', `Server', `Data   localhostThe name or network address of the
Source', `DataSource',            instance of MySQL to which to connect.
`Address', `Addr',                Multiple hosts can be specified
`Network Address'                 separated by &. This can be useful
                                  where multiple MySQL servers are
                                  configured for replication and you are
                                  not concerned about the precise server
                                  you are connecting to. No attempt is
                                  made by the provider to synchronize
                                  writes to the database so care should
                                  be taken when using this option. In
                                  Unix environment with Mono, this can be
                                  a fully qualified path to MySQL socket
                                  filename. With this configuration, the
                                  Unix socket will be used instead of
                                  TCP/IP socket. Currently only a single
                                  socket name can be given so accessing
                                  MySQL in a replicated environment using
                                  Unix sockets is not currently supported.
`Ignore Prepare'          true    When true, instructs the provider to
                                  ignore any calls to
                                  `MySqlCommand.Prepare()'. This option
                                  is provided to prevent issues with
                                  corruption of the statements when use
                                  with server side prepared statements.
                                  If you want to use server-side prepare
                                  statements, set this option to false.
                                  This option was added in Connector/NET
                                  5.0.3 and Connector/NET 1.0.9.
`Port'                    3306    The port MySQL is using to listen for
                                  connections. Specify -1 for this value
                                  to use a named pipe connection (Windows
                                  only).  This value is ignored if Unix
                                  socket is used.
`Protocol'                socket  Specifies the type of connection to
                                  make to the server.Values can be:
                                  socket or tcp for a socket connection
                                  pipe for a named pipe connection unix
                                  for a Unix socket connection memory to
                                  use MySQL shared memory
`CharSet', `Character             Specifies the character set that should
Set'                              be used to encode all queries sent to
                                  the server. Resultsets are still
                                  returned in the character set of the
                                  data returned.
`Logging'                 false   When true, various pieces of
                                  information is output to any configured
                                  TraceListeners.
`Allow Batch'             true    When true, multiple SQL statements can
                                  be sent with one command execution.
                                  -Note- Starting with MySQL 4.1.1, batch
                                  statements should be separated by the
                                  server-defined separator character.
                                  Commands sent to earlier versions of
                                  MySQL should be separated with ';'.
`Encrypt'                 false   For Connector/NET 5.0.3 and later, when
                                  `true', SSL encryption is used for all
                                  data sent between the client and server
                                  if the server has a certificate
                                  installed. Recognized values are
                                  `true', `false', `yes', and `no'. In
                                  versions before 5.0.3, this option had
                                  no effect.
`Initial Catalog',        mysql   The name of the database to use intially
`Database'                        
`Password', `pwd'                 The password for the MySQL account
                                  being used.
`Persist Security Info'   false   When set to `false' or `no' (strongly
                                  recommended), security-sensitive
                                  information, such as the password, is
                                  not returned as part of the connection
                                  if the connection is open or has ever
                                  been in an open state. Resetting the
                                  connection string resets all connection
                                  string values including the password.
                                  Recognized values are `true', `false',
                                  `yes', and `no'.
`User Id', `Username',            The MySQL login account being used.
`Uid', `User name'                
`Shared Memory Name'      MYSQL   The name of the shared memory object to
                                  use for communication if the connection
                                  protocol is set to memory.
`Allow Zero Datetime'     false   True to have MySqlDataReader.GetValue()
                                  return a MySqlDateTime for date or
                                  datetime columns that have illegal
                                  values. False will cause a
                                  `System.DateTime' object to be returned
                                  for legal values and an exception will
                                  be thrown for illegal values.
`Convert Zero Datetime'   false   True to have
                                  `MySqlDataReader.GetValue()' and
                                  `MySqlDataReader.GetDateTime()' return
                                  DateTime.MinValue for date or datetime
                                  columns that have illegal values.
`Old Syntax', `OldSyntax' false   Allows use of '@' symbol as a parameter
                                  marker. See `MySqlCommand' for more
                                  info. This option was deprecated in
                                  Connector/NET 5.2.2. All future code
                                  should be written using the '@' symbol.
`Pipe Name', `Pipe'       mysql   When set to the name of a named pipe,
                                  the `MySqlConnection' will attempt to
                                  connect to MySQL on that named
                                  pipe.This settings only applies to the
                                  Windows platform.
`Procedure Cache'         25      Sets the size of the stored procedure
                                  cache. By default, Connector/NET will
                                  store the metadata (input/output
                                  datatypes) about the last 25 stored
                                  procedures used. To disable the stored
                                  procedure cache, set the value to zero
                                  (0).  This option was added in
                                  Connector/NET 5.0.2 and Connector/NET
                                  1.0.9.
`Use Procedure Bodies'    true    Setting this option to `false'
                                  indicates that the user connecting to
                                  the database does not have the `SELECT'
                                  privileges for the `mysql.proc' (stored
                                  procedures) table. When to set to
                                  `false', Connector/NET will not rely on
                                  this information being available when
                                  the procedure is called. Because
                                  Connector/NET will be unable to
                                  determine this information, you should
                                  explicitly set the types of the all the
                                  parameters before the call and the
                                  parameters should be added to the
                                  command in the exact same order as they
                                  appear in the procedure definition.
                                  This option was added in Connector/NET
                                  5.0.4 and Connector/NET 1.0.10.
`default command timeout'         Sets the default value of the command
                                  timeout to be used. This does not
                                  supercede the individual command
                                  timeout property on an individual
                                  command object. If you set the command
                                  timeout property, that will be used.
                                  This option was added in Connector/NET
                                  5.1.4
`Treat Tiny As Boolean'   true    Setting this value to `false' indicates
                                  that `TINYINT(1)' will be treated as an
                                  `INT'. See also *Note
                                  numeric-type-overview:: for a further
                                  explanation of the `TINYINT' and `BOOL'
                                  data types.
`Allow User Variables'    false   Setting this to `true' indicates that
                                  the provider expects user variables in
                                  the SQL. This option was added in
                                  Connector/NET version 5.2.2.

The following table lists the valid names for connection pooling values
within the `ConnectionString'.  For more information about connection
pooling, see Connection Pooling for the MySQL Data Provider.

Name                      Default Description
`Connection Lifetime'     0       When a connection is returned to the
                                  pool, its creation time is compared
                                  with the current time, and the
                                  connection is destroyed if that time
                                  span (in seconds) exceeds the value
                                  specified by `Connection Lifetime'.
                                  This is useful in clustered
                                  configurations to force load balancing
                                  between a running server and a server
                                  just brought online. A value of zero
                                  (0) causes pooled connections to have
                                  the maximum connection timeout.
`Max Pool Size'           100     The maximum number of connections
                                  allowed in the pool.
`Min Pool Size'           0       The minimum number of connections
                                  allowed in the pool.
`Pooling'                 true    When `true', the `MySqlConnection'
                                  object is drawn from the appropriate
                                  pool, or if necessary, is created and
                                  added to the appropriate pool.
                                  Recognized values are `true', `false',
                                  `yes', and `no'.
`Reset Pooled             true    Specifies whether a ping and a reset
Connections',                     should be sent to the server before a
`ResetConnections',               pooled connection is returned. Not
`ResetPooledConnections'          resetting will yield faster connection
                                  opens but also will not clear out
                                  session items such as temp tables.
`Cache Server             false   Specifies whether server variables
Configuration',                   should be updated when a pooled
`CacheServerConfiguration',        connection is returned. Turning this
`CacheServerConfig'               one will yeild faster opens but will
                                  also not catch any server changes made
                                  by other connections.

When setting keyword or connection pooling values that require a
Boolean value, you can use 'yes' instead of 'true', and 'no' instead of
'false'.

*Note*:

The MySQL Data Provider uses the native socket protocol to communicate
with MySQL. Therefore, it does not support the use of an ODBC data
source name (DSN) when connecting to MySQL because it does not add an
ODBC layer.

*Caution*:

In this release, the application should use caution when constructing a
connection string based on user input (for example when retrieving user
ID and password information from a dialog box, and appending it to the
connection string). The application should ensure that a user cannot
embed extra connection string parameters in these values (for example,
entering a password as "validpassword;database=somedb" in an attempt to
attach to a different database).

*Examples*

The following example creates a `MySqlConnection' and sets some of its
properties

Visual Basic example:

       Public Sub CreateConnection()
         Dim myConnection As New MySqlConnection()
         myConnection.ConnectionString = "Persist Security Info=False;database=myDB;server=myHost;Connect Timeout=30;user id=myUser; pwd=myPass"
         myConnection.Open()
       End Sub 'CreateConnection

C# example:

       public void CreateConnection()
       {
         MySqlConnection myConnection = new MySqlConnection();
         myConnection.ConnectionString = "Persist Security Info=False;database=myDB;server=myHost;Connect Timeout=30;user id=myUser; pwd=myPass";
         myConnection.Open();
       }

*Examples*

The following example creates a `MySqlConnection' in Unix environment
with Mono installed. MySQL socket filename used in this example is
"/var/lib/mysql/mysql.sock". The actual filename depends on your MySQL
configuration.

Visual Basic example:

       Public Sub CreateConnection()
         Dim myConnection As New MySqlConnection()
         myConnection.ConnectionString = "database=myDB;server=/var/lib/mysql/mysql.sock;user id=myUser; pwd=myPass"
         myConnection.Open()
       End Sub 'CreateConnection

C# example:

       public void CreateConnection()
       {
         MySqlConnection myConnection = new MySqlConnection();
         myConnection.ConnectionString = "database=myDB;server=/var/lib/mysql/mysql.sock;user id=myUser; pwd=myPass";
         myConnection.Open();
       }


File: manual.info,  Node: connector-net-examples-mysqlconnection-open,  Next: connector-net-examples-mysqlconnection-database,  Prev: connector-net-examples-mysqlconnection-connectionstring,  Up: connector-net-examples-mysqlconnection

30.2.3.36 Open
..............

Opens a database connection with the property settings specified by the
ConnectionString.

*Exception:* Cannot open a connection without specifying a data source
or server.

*Exception:* A connection-level error occurred while opening the
connection.

The `MySqlConnection' draws an open connection from the connection pool
if one is available.  Otherwise, it establishes a new connection to an
instance of MySQL.

*Examples*

The following example creates a `MySqlConnection', opens it, displays
some of its properties, then closes the connection.

Visual Basic example:

     Public Sub CreateMySqlConnection(myConnString As String)
         Dim myConnection As New MySqlConnection(myConnString)
         myConnection.Open()
         MessageBox.Show("ServerVersion: " + myConnection.ServerVersion _
         + ControlChars.Cr + "State: " + myConnection.State.ToString())
         myConnection.Close()
     End Sub

C# example:

     public void CreateMySqlConnection(string myConnString)
     {
       MySqlConnection myConnection = new MySqlConnection(myConnString);
       myConnection.Open();
       MessageBox.Show("ServerVersion: " + myConnection.ServerVersion +
               "\nState: " + myConnection.State.ToString());
       myConnection.Close();
     }


File: manual.info,  Node: connector-net-examples-mysqlconnection-database,  Next: connector-net-examples-mysqlconnection-state,  Prev: connector-net-examples-mysqlconnection-open,  Up: connector-net-examples-mysqlconnection

30.2.3.37 Database
..................

Gets the name of the current database or the database to be used after
a connection is opened.

*Returns:* The name of the current database or the name of the database
to be used after a connection is opened. The default value is an empty
string.

The `Database' property does not update dynamically. If you change the
current database using a SQL statement, then this property may reflect
the wrong value. If you change the current database using the
`ChangeDatabase' method, this property is updated to reflect the new
database.

*Examples*

The following example creates a `MySqlConnection' and displays some of
its read-only properties.

Visual Basic example:

     Public Sub CreateMySqlConnection()
       Dim myConnString As String = _
         "Persist Security Info=False;database=test;server=localhost;user id=joeuser;pwd=pass"
       Dim myConnection As New MySqlConnection( myConnString )
       myConnection.Open()
       MessageBox.Show( "Server Version: " + myConnection.ServerVersion _
         + ControlChars.NewLine + "Database: " + myConnection.Database )
       myConnection.ChangeDatabase( "test2" )
       MessageBox.Show( "ServerVersion: " + myConnection.ServerVersion _
         + ControlChars.NewLine + "Database: " + myConnection.Database )
       myConnection.Close()
     End Sub

C# example:

     public void CreateMySqlConnection()
     {
       string myConnString =
         "Persist Security Info=False;database=test;server=localhost;user id=joeuser;pwd=pass";
       MySqlConnection myConnection = new MySqlConnection( myConnString );
       myConnection.Open();
       MessageBox.Show( "Server Version: " + myConnection.ServerVersion
         + "\nDatabase: " + myConnection.Database );
       myConnection.ChangeDatabase( "test2" );
       MessageBox.Show( "ServerVersion: " + myConnection.ServerVersion
         + "\nDatabase: " + myConnection.Database );
       myConnection.Close();
     }


File: manual.info,  Node: connector-net-examples-mysqlconnection-state,  Next: connector-net-examples-mysqlconnection-serverversion,  Prev: connector-net-examples-mysqlconnection-database,  Up: connector-net-examples-mysqlconnection

30.2.3.38 State
...............

Gets the current state of the connection.

*Returns:* A bitwise combination of the `System.Data.ConnectionState'
values. The default is `Closed'.

The allowed state changes are:

   * From `Closed' to `Open', using the `Open' method of the connection
     object.

   * From `Open' to `Closed', using either the `Close' method or the
     `Dispose' method of the connection object.

*Examples*

The following example creates a `MySqlConnection', opens it, displays
some of its properties, then closes the connection.

Visual Basic example:

     Public Sub CreateMySqlConnection(myConnString As String)
         Dim myConnection As New MySqlConnection(myConnString)
         myConnection.Open()
         MessageBox.Show("ServerVersion: " + myConnection.ServerVersion _
         + ControlChars.Cr + "State: " + myConnection.State.ToString())
         myConnection.Close()
     End Sub

C# example:

     public void CreateMySqlConnection(string myConnString)
     {
       MySqlConnection myConnection = new MySqlConnection(myConnString);
       myConnection.Open();
       MessageBox.Show("ServerVersion: " + myConnection.ServerVersion +
               "\nState: " + myConnection.State.ToString());
       myConnection.Close();
     }


File: manual.info,  Node: connector-net-examples-mysqlconnection-serverversion,  Next: connector-net-examples-mysqlconnection-close,  Prev: connector-net-examples-mysqlconnection-state,  Up: connector-net-examples-mysqlconnection

30.2.3.39 ServerVersion
.......................

Gets a string containing the version of the MySQL server to which the
client is connected.

*Returns:* The version of the instance of MySQL.

*Exception:* The connection is closed.

*Examples*

The following example creates a `MySqlConnection', opens it, displays
some of its properties, then closes the connection.

Visual Basic example:

     Public Sub CreateMySqlConnection(myConnString As String)
         Dim myConnection As New MySqlConnection(myConnString)
         myConnection.Open()
         MessageBox.Show("ServerVersion: " + myConnection.ServerVersion _
         + ControlChars.Cr + "State: " + myConnection.State.ToString())
         myConnection.Close()
     End Sub

C# example:

     public void CreateMySqlConnection(string myConnString)
     {
       MySqlConnection myConnection = new MySqlConnection(myConnString);
       myConnection.Open();
       MessageBox.Show("ServerVersion: " + myConnection.ServerVersion +
               "\nState: " + myConnection.State.ToString());
       myConnection.Close();
     }


File: manual.info,  Node: connector-net-examples-mysqlconnection-close,  Next: connector-net-examples-mysqlconnection-createcommand,  Prev: connector-net-examples-mysqlconnection-serverversion,  Up: connector-net-examples-mysqlconnection

30.2.3.40 Close
...............

Closes the connection to the database. This is the preferred method of
closing any open connection.

The `Close' method rolls back any pending transactions. It then
releases the connection to the connection pool, or closes the
connection if connection pooling is disabled.

An application can call `Close' more than one time. No exception is
generated.

*Examples*

The following example creates a `MySqlConnection', opens it, displays
some of its properties, then closes the connection.

Visual Basic example:

     Public Sub CreateMySqlConnection(myConnString As String)
         Dim myConnection As New MySqlConnection(myConnString)
         myConnection.Open()
         MessageBox.Show("ServerVersion: " + myConnection.ServerVersion _
         + ControlChars.Cr + "State: " + myConnection.State.ToString())
         myConnection.Close()
     End Sub

C# example:

     public void CreateMySqlConnection(string myConnString)
     {
       MySqlConnection myConnection = new MySqlConnection(myConnString);
       myConnection.Open();
       MessageBox.Show("ServerVersion: " + myConnection.ServerVersion +
               "\nState: " + myConnection.State.ToString());
       myConnection.Close();
     }


File: manual.info,  Node: connector-net-examples-mysqlconnection-createcommand,  Next: connector-net-examples-mysqlconnection-begintransaction,  Prev: connector-net-examples-mysqlconnection-close,  Up: connector-net-examples-mysqlconnection

30.2.3.41 CreateCommand
.......................

Creates and returns a `MySqlCommand' object associated with the
`MySqlConnection'.

*Returns:* A `MySqlCommand' object.


File: manual.info,  Node: connector-net-examples-mysqlconnection-begintransaction,  Next: connector-net-examples-mysqlconnection-begintransaction1,  Prev: connector-net-examples-mysqlconnection-createcommand,  Up: connector-net-examples-mysqlconnection

30.2.3.42 BeginTransaction
..........................

Begins a database transaction.

*Returns:* An object representing the new transaction.

*Exception:* Parallel transactions are not supported.

This command is equivalent to the MySQL BEGIN TRANSACTION command.

You must explicitly commit or roll back the transaction using the
`MySqlTransaction.Commit' or `MySqlTransaction.Rollback' method.

*Note*:

If you do not specify an isolation level, the default isolation level
is used. To specify an isolation level with the `BeginTransaction'
method, use the overload that takes the `iso' parameter.

*Examples*

The following example creates a `MySqlConnection' and a
`MySqlTransaction'. It also demonstrates how to use the
`BeginTransaction', a `MySqlTransaction.Commit', and
`MySqlTransaction.Rollback' methods.

Visual Basic example:

     Public Sub RunTransaction(myConnString As String)
         Dim myConnection As New MySqlConnection(myConnString)
         myConnection.Open()

         Dim myCommand As MySqlCommand = myConnection.CreateCommand()
         Dim myTrans As MySqlTransaction

         ' Start a local transaction
         myTrans = myConnection.BeginTransaction()
         ' Must assign both transaction object and connection
         ' to Command object for a pending local transaction
         myCommand.Connection = myConnection
         myCommand.Transaction = myTrans

         Try
           myCommand.CommandText = "Insert into Test (id, desc) VALUES (100, 'Description')"
           myCommand.ExecuteNonQuery()
           myCommand.CommandText = "Insert into Test (id, desc) VALUES (101, 'Description')"
           myCommand.ExecuteNonQuery()
           myTrans.Commit()
           Console.WriteLine("Both records are written to database.")
         Catch e As Exception
           Try
             myTrans.Rollback()
           Catch ex As MySqlException
             If Not myTrans.Connection Is Nothing Then
               Console.WriteLine("An exception of type " + ex.GetType().ToString() + _
                                 " was encountered while attempting to roll back the transaction.")
             End If
           End Try

           Console.WriteLine("An exception of type " + e.GetType().ToString() + _
                           "was encountered while inserting the data.")
           Console.WriteLine("Neither record was written to database.")
         Finally
           myConnection.Close()
         End Try
     End Sub

C# example:

     public void RunTransaction(string myConnString)
     {
       MySqlConnection myConnection = new MySqlConnection(myConnString);
       myConnection.Open();
       MySqlCommand myCommand = myConnection.CreateCommand();
       MySqlTransaction myTrans;
       // Start a local transaction
       myTrans = myConnection.BeginTransaction();
       // Must assign both transaction object and connection
       // to Command object for a pending local transaction
       myCommand.Connection = myConnection;
       myCommand.Transaction = myTrans;
         try
         {
           myCommand.CommandText = "insert into Test (id, desc) VALUES (100, 'Description')";
           myCommand.ExecuteNonQuery();
           myCommand.CommandText = "insert into Test (id, desc) VALUES (101, 'Description')";
           myCommand.ExecuteNonQuery();
           myTrans.Commit();
           Console.WriteLine("Both records are written to database.");
         }
         catch(Exception e)
         {
           try
           {
             myTrans.Rollback();
           }
           catch (SqlException ex)
           {
             if (myTrans.Connection != null)
             {
               Console.WriteLine("An exception of type " + ex.GetType() +
                                 " was encountered while attempting to roll back the transaction.");
             }
           }

           Console.WriteLine("An exception of type " + e.GetType() +
                             " was encountered while inserting the data.");
           Console.WriteLine("Neither record was written to database.");
         }
         finally
         {
           myConnection.Close();
         }
     }


File: manual.info,  Node: connector-net-examples-mysqlconnection-begintransaction1,  Next: connector-net-examples-mysqlconnection-changedatabase,  Prev: connector-net-examples-mysqlconnection-begintransaction,  Up: connector-net-examples-mysqlconnection

30.2.3.43 BeginTransaction1
...........................

Begins a database transaction with the specified isolation level.

*Parameters:* The isolation level under which the transaction should
run.

*Returns:* An object representing the new transaction.

*Exception:* Parallel exceptions are not supported.

This command is equivalent to the MySQL BEGIN TRANSACTION command.

You must explicitly commit or roll back the transaction using the
`MySqlTransaction.Commit' or `MySqlTransaction.Rollback' method.

*Note*:

If you do not specify an isolation level, the default isolation level
is used. To specify an isolation level with the `BeginTransaction'
method, use the overload that takes the `iso' parameter.

*Examples*

The following example creates a `MySqlConnection' and a
`MySqlTransaction'. It also demonstrates how to use the
`BeginTransaction', a `MySqlTransaction.Commit', and
`MySqlTransaction.Rollback' methods.

Visual Basic example:

     Public Sub RunTransaction(myConnString As String)
         Dim myConnection As New MySqlConnection(myConnString)
         myConnection.Open()

         Dim myCommand As MySqlCommand = myConnection.CreateCommand()
         Dim myTrans As MySqlTransaction

         ' Start a local transaction
         myTrans = myConnection.BeginTransaction()
         ' Must assign both transaction object and connection
         ' to Command object for a pending local transaction
         myCommand.Connection = myConnection
         myCommand.Transaction = myTrans

         Try
           myCommand.CommandText = "Insert into Test (id, desc) VALUES (100, 'Description')"
           myCommand.ExecuteNonQuery()
           myCommand.CommandText = "Insert into Test (id, desc) VALUES (101, 'Description')"
           myCommand.ExecuteNonQuery()
           myTrans.Commit()
           Console.WriteLine("Both records are written to database.")
         Catch e As Exception
           Try
             myTrans.Rollback()
           Catch ex As MySqlException
             If Not myTrans.Connection Is Nothing Then
               Console.WriteLine("An exception of type " + ex.GetType().ToString() + _
                                 " was encountered while attempting to roll back the transaction.")
             End If
           End Try

           Console.WriteLine("An exception of type " + e.GetType().ToString() + _
                           "was encountered while inserting the data.")
           Console.WriteLine("Neither record was written to database.")
         Finally
           myConnection.Close()
         End Try
     End Sub

C# example:

     public void RunTransaction(string myConnString)
     {
       MySqlConnection myConnection = new MySqlConnection(myConnString);
       myConnection.Open();
       MySqlCommand myCommand = myConnection.CreateCommand();
       MySqlTransaction myTrans;
       // Start a local transaction
       myTrans = myConnection.BeginTransaction();
       // Must assign both transaction object and connection
       // to Command object for a pending local transaction
       myCommand.Connection = myConnection;
       myCommand.Transaction = myTrans;
         try
         {
           myCommand.CommandText = "insert into Test (id, desc) VALUES (100, 'Description')";
           myCommand.ExecuteNonQuery();
           myCommand.CommandText = "insert into Test (id, desc) VALUES (101, 'Description')";
           myCommand.ExecuteNonQuery();
           myTrans.Commit();
           Console.WriteLine("Both records are written to database.");
         }
         catch(Exception e)
         {
           try
           {
             myTrans.Rollback();
           }
           catch (SqlException ex)
           {
             if (myTrans.Connection != null)
             {
               Console.WriteLine("An exception of type " + ex.GetType() +
                                 " was encountered while attempting to roll back the transaction.");
             }
           }

           Console.WriteLine("An exception of type " + e.GetType() +
                             " was encountered while inserting the data.");
           Console.WriteLine("Neither record was written to database.");
         }
         finally
         {
           myConnection.Close();
         }
     }


File: manual.info,  Node: connector-net-examples-mysqlconnection-changedatabase,  Next: connector-net-examples-mysqlconnection-statechange,  Prev: connector-net-examples-mysqlconnection-begintransaction1,  Up: connector-net-examples-mysqlconnection

30.2.3.44 ChangeDatabase
........................

Changes the current database for an open MySqlConnection.

*Parameters:* The name of the database to use.

The value supplied in the `database' parameter must be a valid database
name. The `database' parameter cannot contain a null value, an empty
string, or a string with only blank characters.

When you are using connection pooling against MySQL, and you close the
connection, it is returned to the connection pool.  The next time the
connection is retrieved from the pool, the reset connection request
executes before the user performs any operations.

MySQL Enterprise

MySQL Enterprise subscribers will find more information on this subject
in the Knowledge Base article, Understanding and Using Connection
Pooling (https://kb.mysql.com/view.php?id=4918). Access to the MySQL
Knowledge Base collection of articles is one of the advantages of
subscribing to MySQL Enterprise. To subscribe see
`http://www.mysql.com/products/enterprise/advisors.html'.

*Exception:* The database name is not valid.

*Exception:* The connection is not open.

*Exception:* Cannot change the database.

*Examples*

The following example creates a `MySqlConnection' and displays some of
its read-only properties.

Visual Basic example:

     Public Sub CreateMySqlConnection()
       Dim myConnString As String = _
         "Persist Security Info=False;database=test;server=localhost;user id=joeuser;pwd=pass"
       Dim myConnection As New MySqlConnection( myConnString )
       myConnection.Open()
       MessageBox.Show( "Server Version: " + myConnection.ServerVersion _
         + ControlChars.NewLine + "Database: " + myConnection.Database )
       myConnection.ChangeDatabase( "test2" )
       MessageBox.Show( "ServerVersion: " + myConnection.ServerVersion _
         + ControlChars.NewLine + "Database: " + myConnection.Database )
       myConnection.Close()
     End Sub

C# example:

     public void CreateMySqlConnection()
     {
       string myConnString =
         "Persist Security Info=False;database=test;server=localhost;user id=joeuser;pwd=pass";
       MySqlConnection myConnection = new MySqlConnection( myConnString );
       myConnection.Open();
       MessageBox.Show( "Server Version: " + myConnection.ServerVersion
         + "\nDatabase: " + myConnection.Database );
       myConnection.ChangeDatabase( "test2" );
       MessageBox.Show( "ServerVersion: " + myConnection.ServerVersion
         + "\nDatabase: " + myConnection.Database );
       myConnection.Close();
     }


File: manual.info,  Node: connector-net-examples-mysqlconnection-statechange,  Next: connector-net-examples-mysqlconnection-infomessage,  Prev: connector-net-examples-mysqlconnection-changedatabase,  Up: connector-net-examples-mysqlconnection

30.2.3.45 StateChange
.....................

Occurs when the state of the connection changes.

The `StateChange' event fires whenever the `State' changes from closed
to opened, or from opened to closed. `StateChange' fires immediately
after the `MySqlConnection' transitions.

If an event handler throws an exception from within the `StateChange'
event, the exception propagates to the caller of the `Open' or `Close'
method.

The `StateChange' event is not raised unless you explicitly call
`Close' or `Dispose'.

The event handler receives an argument of type
`System.Data.StateChangeEventArgs' containing data related to this
event. The following `StateChangeEventArgs' properties provide
information specific to this event.

* Property*                          Description
*                                    Gets the new state of the
`System.Data.StateChangeEventArgs.CurrentState'connection. The connection object
*                                    will be in the new state already
                                     when the event is fired.
*                                    Gets the original state of the
`System.Data.StateChangeEventArgs.OriginalState'connection.
*                                    


File: manual.info,  Node: connector-net-examples-mysqlconnection-infomessage,  Next: connector-net-examples-mysqlconnection-connectiontimeout,  Prev: connector-net-examples-mysqlconnection-statechange,  Up: connector-net-examples-mysqlconnection

30.2.3.46 InfoMessage
.....................

Occurs when MySQL returns warnings as a result of executing a command
or query.


File: manual.info,  Node: connector-net-examples-mysqlconnection-connectiontimeout,  Prev: connector-net-examples-mysqlconnection-infomessage,  Up: connector-net-examples-mysqlconnection

30.2.3.47 ConnectionTimeout
...........................

Gets the time to wait while trying to establish a connection before
terminating the attempt and generating an error.

*Exception:* The value set is less than 0.

A value of 0 indicates no limit, and should be avoided in a
`MySqlConnection.ConnectionString' because an attempt to connect will
wait indefinitely.

*Examples*

The following example creates a MySqlConnection and sets some of its
properties in the connection string.

Visual Basic example:

     Public Sub CreateSqlConnection()
       Dim myConnection As New MySqlConnection()
       myConnection.ConnectionString = "Persist Security Info=False;Username=user;Password=pass;database=test1;server=localhost;Connect Timeout=30"
       myConnection.Open()
     End Sub

C# example:

     public void CreateSqlConnection()
     {
       MySqlConnection myConnection = new MySqlConnection();
       myConnection.ConnectionString = "Persist Security Info=False;Username=user;»
           Password=pass;database=test1;server=localhost;Connect Timeout=30";
       myConnection.Open();
     }


File: manual.info,  Node: connector-net-examples-mysqldataadapter,  Next: connector-net-examples-mysqldatareader,  Prev: connector-net-examples-mysqlconnection,  Up: connector-net-examples

30.2.3.48 Using `MySqlDataAdapter'
..................................

* Menu:

* connector-net-examples-mysqldataadapter-ctor::  Class MySqlDataAdapter Constructor
* connector-net-examples-mysqldataadapter-ctor1::  Class MySqlDataAdapter Constructor Form 1
* connector-net-examples-mysqldataadapter-ctor2::  Class MySqlDataAdapter Constructor Form 2
* connector-net-examples-mysqldataadapter-ctor3::  Class MySqlDataAdapter Constructor Form 3
* connector-net-examples-mysqldataadapter-deletecommand::  DeleteCommand
* connector-net-examples-mysqldataadapter-insertcommand::  InsertCommand
* connector-net-examples-mysqldataadapter-updatecommand::  UpdateCommand
* connector-net-examples-mysqldataadapter-selectcommand::  SelectCommand

Represents a set of data commands and a database connection that are
used to fill a data set and update a MySQL database. This class cannot
be inherited.

The `MySQLDataAdapter', serves as a bridge between a
`System.Data.DataSet' and MySQL for retrieving and saving data. The
`MySQLDataAdapter' provides this bridge by mapping
`DbDataAdapter.Fill', which changes the data in the `DataSet' to match
the data in the data source, and `DbDataAdapter.Update', which changes
the data in the data source to match the data in the `DataSet', using
the appropriate SQL statements against the data source.

When the `MySQLDataAdapter' fills a `DataSet', it will create the
necessary tables and columns for the returned data if they do not
already exist.  However, primary key information will not be included
in the implicitly created schema unless the
`System.Data.MissingSchemaAction' property is set to
`System.Data.MissingSchemaAction.AddWithKey'.  You may also have the
`MySQLDataAdapter' create the schema of the `DataSet', including primary
key information, before filling it with data using
`System.Data.Common.DbDataAdapter.FillSchema'.

`MySQLDataAdapter' is used in conjunction with `MySqlConnection' and
`MySqlCommand' to increase performance when connecting to a MySQL
database.

The `MySQLDataAdapter' also includes the
`MySqlDataAdapter.SelectCommand', `MySqlDataAdapter.InsertCommand',
`MySqlDataAdapter.DeleteCommand', `MySqlDataAdapter.UpdateCommand', and
`DataAdapter.TableMappings' properties to facilitate the loading and
updating of data.

When an instance of `MySQLDataAdapter' is created, the read/write
properties are set to initial values.  For a list of these values, see
the `MySQLDataAdapter' constructor.

*Note*:

Please be aware that the `DataColumn' class in .NET only allows columns
with type of Int16, Int32, or Int64 to be autoincrement columns. If you
plan to use autoincremement columns with MySQL, you should consider
using signed integer columns.

*Examples*

The following example creates a `MySqlCommand' and a `MySqlConnection'.
The `MySqlConnection' is opened and set as the
`MySqlCommand.Connection' for the `MySqlCommand'. The example then calls
`MySqlCommand.ExecuteNonQuery', and closes the connection. To
accomplish this, the `ExecuteNonQuery' is passed a connection string
and a query string that is a SQL INSERT statement.

Visual Basic example:

     Public Function SelectRows(dataSet As DataSet, connection As String, query As String) As DataSet
         Dim conn As New MySqlConnection(connection)
         Dim adapter As New MySqlDataAdapter()
         adapter.SelectCommand = new MySqlCommand(query, conn)
         adapter.Fill(dataset)
         Return dataset
     End Function

C# example:

     public DataSet SelectRows(DataSet dataset,string connection,string query)
     {
         MySqlConnection conn = new MySqlConnection(connection);
         MySqlDataAdapter adapter = new MySqlDataAdapter();
         adapter.SelectCommand = new MySqlCommand(query, conn);
         adapter.Fill(dataset);
         return dataset;
     }


File: manual.info,  Node: connector-net-examples-mysqldataadapter-ctor,  Next: connector-net-examples-mysqldataadapter-ctor1,  Prev: connector-net-examples-mysqldataadapter,  Up: connector-net-examples-mysqldataadapter

30.2.3.49 Class MySqlDataAdapter Constructor
............................................

*Overload methods for MySqlDataAdapter*

Initializes a new instance of the MySqlDataAdapter class.

When an instance of `MySqlDataAdapter' is created, the following
read/write properties are set to the following initial values.

* Properties*                        * Initial Value*
* `MissingMappingAction' *           * `MissingMappingAction.Passthrough'
                                     *
* `MissingSchemaAction' *            * `MissingSchemaAction.Add' *

You can change the value of any of these properties through a separate
call to the property.

*Examples*

The following example creates a `MySqlDataAdapter' and sets some of its
properties.

Visual Basic example:


     Public Sub CreateSqlDataAdapter()
         Dim conn As MySqlConnection = New MySqlConnection("Data Source=localhost;" & _
         "database=test")
         Dim da As MySqlDataAdapter = New MySqlDataAdapter
         da.MissingSchemaAction = MissingSchemaAction.AddWithKey

         da.SelectCommand = New MySqlCommand("SELECT id, name FROM mytable", conn)
         da.InsertCommand = New MySqlCommand("INSERT INTO mytable (id, name) " & _
                                                 "VALUES (@id, @name)", conn)
         da.UpdateCommand = New MySqlCommand("UPDATE mytable SET id=@id, name=@name " & _
                                                 "WHERE id=@oldId", conn)
         da.DeleteCommand = New MySqlCommand("DELETE FROM mytable WHERE id=@id", conn)
         da.InsertCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id")
         da.InsertCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name")

         da.UpdateCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id")
         da.UpdateCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name")
         da.UpdateCommand.Parameters.Add("@oldId", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original
         da.DeleteCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original
     End Sub

C# example:

     public static void CreateSqlDataAdapter()
     {
         MySqlConnection conn = new MySqlConnection("Data Source=localhost;database=test");
         MySqlDataAdapter da = new MySqlDataAdapter();
         da.MissingSchemaAction = MissingSchemaAction.AddWithKey;

         da.SelectCommand = new MySqlCommand("SELECT id, name FROM mytable", conn);
         da.InsertCommand = new MySqlCommand("INSERT INTO mytable (id, name) " +
                                                 "VALUES (@id, @name)", conn);
         da.UpdateCommand = new MySqlCommand("UPDATE mytable SET id=@id, name=@name " +
                                                 "WHERE id=@oldId", conn);
         da.DeleteCommand = new MySqlCommand("DELETE FROM mytable WHERE id=@id", conn);
         da.InsertCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id");
         da.InsertCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name");

         da.UpdateCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id");
         da.UpdateCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name");
         da.UpdateCommand.Parameters.Add("@oldId", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original;
         da.DeleteCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original;
     }


File: manual.info,  Node: connector-net-examples-mysqldataadapter-ctor1,  Next: connector-net-examples-mysqldataadapter-ctor2,  Prev: connector-net-examples-mysqldataadapter-ctor,  Up: connector-net-examples-mysqldataadapter

30.2.3.50 Class MySqlDataAdapter Constructor Form 1
...................................................

Initializes a new instance of the `MySqlDataAdapter' class with the
specified `MySqlCommand' as the `SelectCommand' property.

*Parameters:* `MySqlCommand' that is a SQL `SELECT' statement or stored
procedure and is set as the `SelectCommand' property of the
`MySqlDataAdapter'.

When an instance of `MySqlDataAdapter' is created, the following
read/write properties are set to the following initial values.

* Properties*                        * Initial Value*
* `MissingMappingAction' *           * `MissingMappingAction.Passthrough'
                                     *
* `MissingSchemaAction' *            * `MissingSchemaAction.Add' *

You can change the value of any of these properties through a separate
call to the property.

When `SelectCommand' (or any of the other command properties) is
assigned to a previously created `MySqlCommand', the `MySqlCommand' is
not cloned. The `SelectCommand' maintains a reference to the previously
created `MySqlCommand' object.

*Examples*

The following example creates a `MySqlDataAdapter' and sets some of its
properties.

Visual Basic example:


     Public Sub CreateSqlDataAdapter()
         Dim conn As MySqlConnection = New MySqlConnection("Data Source=localhost;" & _
         "database=test")
       Dim cmd as new MySqlCommand("SELECT id, name FROM mytable", conn)
         Dim da As MySqlDataAdapter = New MySqlDataAdapter(cmd)
         da.MissingSchemaAction = MissingSchemaAction.AddWithKey

         da.InsertCommand = New MySqlCommand("INSERT INTO mytable (id, name) " & _
                                                 "VALUES (@id, @name)", conn)
         da.UpdateCommand = New MySqlCommand("UPDATE mytable SET id=@id, name=@name " & _
                                                 "WHERE id=@oldId", conn)
         da.DeleteCommand = New MySqlCommand("DELETE FROM mytable WHERE id=@id", conn)
         da.InsertCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id")
         da.InsertCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name")

         da.UpdateCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id")
         da.UpdateCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name")
         da.UpdateCommand.Parameters.Add("@oldId", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original
         da.DeleteCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original
     End Sub

C# example:

     public static void CreateSqlDataAdapter()
     {
         MySqlConnection conn = new MySqlConnection("Data Source=localhost;database=test");
         MySqlCommand cmd = new MySqlCommand("SELECT id, name FROM mytable", conn);
         MySqlDataAdapter da = new MySqlDataAdapter(cmd);
         da.MissingSchemaAction = MissingSchemaAction.AddWithKey;

         da.InsertCommand = new MySqlCommand("INSERT INTO mytable (id, name) " +
                                                 "VALUES (@id, @name)", conn);
         da.UpdateCommand = new MySqlCommand("UPDATE mytable SET id=@id, name=@name " +
                                                 "WHERE id=@oldId", conn);
         da.DeleteCommand = new MySqlCommand("DELETE FROM mytable WHERE id=@id", conn);
         da.InsertCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id");
         da.InsertCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name");

         da.UpdateCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id");
         da.UpdateCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name");
         da.UpdateCommand.Parameters.Add("@oldId", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original;
         da.DeleteCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original;
     }


File: manual.info,  Node: connector-net-examples-mysqldataadapter-ctor2,  Next: connector-net-examples-mysqldataadapter-ctor3,  Prev: connector-net-examples-mysqldataadapter-ctor1,  Up: connector-net-examples-mysqldataadapter

30.2.3.51 Class MySqlDataAdapter Constructor Form 2
...................................................

Initializes a new instance of the `MySqlDataAdapter' class with a
`SelectCommand' and a `MySqlConnection' object.

*Parameters:* A `String' that is a SQL `SELECT' statement or stored
procedure to be used by the `SelectCommand' property of the
`MySqlDataAdapter'.

*Parameters:* A `MySqlConnection' that represents the connection.

This implementation of the `MySqlDataAdapter' opens and closes a
`MySqlConnection' if it is not already open. This can be useful in a an
application that must call the `DbDataAdapter.Fill' method for two or
more `MySqlDataAdapter' objects. If the `MySqlConnection' is already
open, you must explicitly call `MySqlConnection.Close' or
`MySqlConnection.Dispose' to close it.

When an instance of `MySqlDataAdapter' is created, the following
read/write properties are set to the following initial values.

* Properties*                        * Initial Value*
* `MissingMappingAction' *           * `MissingMappingAction.Passthrough'
                                     *
* `MissingSchemaAction' *            * `MissingSchemaAction.Add' *

You can change the value of any of these properties through a separate
call to the property.

*Examples*

The following example creates a `MySqlDataAdapter' and sets some of its
properties.

Visual Basic example:


     Public Sub CreateSqlDataAdapter()
         Dim conn As MySqlConnection = New MySqlConnection("Data Source=localhost;" & _
         "database=test")
         Dim da As MySqlDataAdapter = New MySqlDataAdapter("SELECT id, name FROM mytable", conn)
         da.MissingSchemaAction = MissingSchemaAction.AddWithKey

         da.InsertCommand = New MySqlCommand("INSERT INTO mytable (id, name) " & _
                                                 "VALUES (@id, @name)", conn)
         da.UpdateCommand = New MySqlCommand("UPDATE mytable SET id=@id, name=@name " & _
                                                 "WHERE id=@oldId", conn)
         da.DeleteCommand = New MySqlCommand("DELETE FROM mytable WHERE id=@id", conn)
         da.InsertCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id")
         da.InsertCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name")

         da.UpdateCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id")
         da.UpdateCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name")
         da.UpdateCommand.Parameters.Add("@oldId", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original
         da.DeleteCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original
     End Sub

C# example:

     public static void CreateSqlDataAdapter()
     {
         MySqlConnection conn = new MySqlConnection("Data Source=localhost;database=test");
         MySqlDataAdapter da = new MySqlDataAdapter("SELECT id, name FROM mytable", conn);
         da.MissingSchemaAction = MissingSchemaAction.AddWithKey;

         da.InsertCommand = new MySqlCommand("INSERT INTO mytable (id, name) " +
                                                 "VALUES (@id, @name)", conn);
         da.UpdateCommand = new MySqlCommand("UPDATE mytable SET id=@id, name=@name " +
                                                 "WHERE id=@oldId", conn);
         da.DeleteCommand = new MySqlCommand("DELETE FROM mytable WHERE id=@id", conn);
         da.InsertCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id");
         da.InsertCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name");

         da.UpdateCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id");
         da.UpdateCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name");
         da.UpdateCommand.Parameters.Add("@oldId", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original;
         da.DeleteCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original;
     }


File: manual.info,  Node: connector-net-examples-mysqldataadapter-ctor3,  Next: connector-net-examples-mysqldataadapter-deletecommand,  Prev: connector-net-examples-mysqldataadapter-ctor2,  Up: connector-net-examples-mysqldataadapter

30.2.3.52 Class MySqlDataAdapter Constructor Form 3
...................................................

Initializes a new instance of the `MySqlDataAdapter' class with a
`SelectCommand' and a connection string.

*Parameters:* A `string' that is a SQL `SELECT' statement or stored
procedure to be used by the `SelectCommand' property of the
`MySqlDataAdapter'.

*Parameters:* The connection string

When an instance of `MySqlDataAdapter' is created, the following
read/write properties are set to the following initial values.

* Properties*                        * Initial Value*
* `MissingMappingAction' *           * `MissingMappingAction.Passthrough'
                                     *
* `MissingSchemaAction' *            * `MissingSchemaAction.Add' *

You can change the value of any of these properties through a separate
call to the property.

*Examples*

The following example creates a `MySqlDataAdapter' and sets some of its
properties.

Visual Basic example:


     Public Sub CreateSqlDataAdapter()
         Dim da As MySqlDataAdapter = New MySqlDataAdapter("SELECT id, name FROM mytable", "Data Source=localhost;database=test")
         Dim conn As MySqlConnection = da.SelectCommand.Connection
         da.MissingSchemaAction = MissingSchemaAction.AddWithKey

         da.InsertCommand = New MySqlCommand("INSERT INTO mytable (id, name) " & _
                                                 "VALUES (@id, @name)", conn)
         da.UpdateCommand = New MySqlCommand("UPDATE mytable SET id=@id, name=@name " & _
                                                 "WHERE id=@oldId", conn)
         da.DeleteCommand = New MySqlCommand("DELETE FROM mytable WHERE id=@id", conn)
         da.InsertCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id")
         da.InsertCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name")

         da.UpdateCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id")
         da.UpdateCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name")
         da.UpdateCommand.Parameters.Add("@oldId", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original
         da.DeleteCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original
     End Sub

C# example:

     public static void CreateSqlDataAdapter()
     {
         MySqlDataAdapter da = new MySqlDataAdapter("SELECT id, name FROM mytable", "Data Source=localhost;database=test");
         MySqlConnection conn = da.SelectCommand.Connection;
         da.MissingSchemaAction = MissingSchemaAction.AddWithKey;

         da.InsertCommand = new MySqlCommand("INSERT INTO mytable (id, name) " +
                                                 "VALUES (@id, @name)", conn);
         da.UpdateCommand = new MySqlCommand("UPDATE mytable SET id=@id, name=@name " +
                                                 "WHERE id=@oldId", conn);
         da.DeleteCommand = new MySqlCommand("DELETE FROM mytable WHERE id=@id", conn);
         da.InsertCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id");
         da.InsertCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name");

         da.UpdateCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id");
         da.UpdateCommand.Parameters.Add("@name", MySqlDbType.VarChar, 40, "name");
         da.UpdateCommand.Parameters.Add("@oldId", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original;
         da.DeleteCommand.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id").SourceVersion = DataRowVersion.Original;
     }


File: manual.info,  Node: connector-net-examples-mysqldataadapter-deletecommand,  Next: connector-net-examples-mysqldataadapter-insertcommand,  Prev: connector-net-examples-mysqldataadapter-ctor3,  Up: connector-net-examples-mysqldataadapter

30.2.3.53 DeleteCommand
.......................

Gets or sets a SQL statement or stored procedure used to delete records
from the data set.

*Value:* A `MySqlCommand' used during
`System.Data.Common.DataAdapter.Update' to delete records in the
database that correspond to deleted rows in the `DataSet'.

During `System.Data.Common.DataAdapter.Update', if this property is not
set and primary key information is present in the `DataSet', the
`DeleteCommand' can be generated automatically if you set the
`SelectCommand' property and use the `MySqlCommandBuilder'.  Then, any
additional commands that you do not set are generated by the
`MySqlCommandBuilder'. This generation logic requires key column
information to be present in the `DataSet'.

When `DeleteCommand' is assigned to a previously created
`MySqlCommand', the `MySqlCommand' is not cloned. The `DeleteCommand'
maintains a reference to the previously created `MySqlCommand' object.

*Examples*

The following example creates a `MySqlDataAdapter' and sets the
`SelectCommand' and `DeleteCommand' properties. It assumes you have
already created a `MySqlConnection' object.

Visual Basic example:

     Public Shared Function CreateCustomerAdapter(conn As MySqlConnection) As MySqlDataAdapter

       Dim da As MySqlDataAdapter = New MySqlDataAdapter()
       Dim cmd As MySqlCommand
       Dim parm As MySqlParameter
       ' Create the SelectCommand.
       cmd = New MySqlCommand("SELECT * FROM mytable WHERE id=@id AND name=@name", conn)
       cmd.Parameters.Add("@id", MySqlDbType.VarChar, 15)
       cmd.Parameters.Add("@name", MySqlDbType.VarChar, 15)
       da.SelectCommand = cmd
       ' Create the DeleteCommand.
       cmd = New MySqlCommand("DELETE FROM mytable WHERE id=@id", conn)
       parm = cmd.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id")
       parm.SourceVersion = DataRowVersion.Original
       da.DeleteCommand = cmd
       Return da
     End Function

C# example:

     public static MySqlDataAdapter CreateCustomerAdapter(MySqlConnection conn)
     {
       MySqlDataAdapter da = new MySqlDataAdapter();
       MySqlCommand cmd;
       MySqlParameter parm;
       // Create the SelectCommand.
       cmd = new MySqlCommand("SELECT * FROM mytable WHERE id=@id AND name=@name", conn);
       cmd.Parameters.Add("@id", MySqlDbType.VarChar, 15);
       cmd.Parameters.Add("@name", MySqlDbType.VarChar, 15);
       da.SelectCommand = cmd;
       // Create the DeleteCommand.
       cmd = new MySqlCommand("DELETE FROM mytable WHERE id=@id", conn);
       parm = cmd.Parameters.Add("@id", MySqlDbType.VarChar, 5, "id");
       parm.SourceVersion = DataRowVersion.Original;
       da.DeleteCommand = cmd;
       return da;
     }


File: manual.info,  Node: connector-net-examples-mysqldataadapter-insertcommand,  Next: connector-net-examples-mysqldataadapter-updatecommand,  Prev: connector-net-examples-mysqldataadapter-deletecommand,  Up: connector-net-examples-mysqldataadapter

30.2.3.54 InsertCommand
.......................

Gets or sets a SQL statement or stored procedure used to insert records
into the data set.

*Value:* A `MySqlCommand' used during
`System.Data.Common.DataAdapter.Update' to insert records into the
database that correspond to new rows in the `DataSet'.

During `System.Data.Common.DataAdapter.Update', if this property is not
set and primary key information is present in the `DataSet', the
`InsertCommand' can be generated automatically if you set the
`SelectCommand' property and use the `MySqlCommandBuilder'.  Then, any
additional commands that you do not set are generated by the
`MySqlCommandBuilder'. This generation logic requires key column
information to be present in the `DataSet'.

When `InsertCommand' is assigned to a previously created
`MySqlCommand', the `MySqlCommand' is not cloned. The `InsertCommand'
maintains a reference to the previously created `MySqlCommand' object.

*Note*:

If execution of this command returns rows, these rows may be added to
the `DataSet' depending on how you set the
`MySqlCommand.UpdatedRowSource' property of the `MySqlCommand' object.

*Examples*

The following example creates a `MySqlDataAdapter' and sets the
`SelectCommand' and `InsertCommand' properties. It assumes you have
already created a `MySqlConnection' object.

Visual Basic example:

     Public Shared Function CreateCustomerAdapter(conn As MySqlConnection) As MySqlDataAdapter

       Dim da As MySqlDataAdapter = New MySqlDataAdapter()
       Dim cmd As MySqlCommand
       Dim parm As MySqlParameter
       ' Create the SelectCommand.
       cmd = New MySqlCommand("SELECT * FROM mytable WHERE id=@id AND name=@name", conn)
       cmd.Parameters.Add("@id", MySqlDbType.VarChar, 15)
       cmd.Parameters.Add("@name", MySqlDbType.VarChar, 15)
       da.SelectCommand = cmd
       ' Create the InsertCommand.
       cmd = New MySqlCommand("INSERT INTO mytable (id,name) VALUES (@id, @name)", conn)
       cmd.Parameters.Add( "@id", MySqlDbType.VarChar, 15, "id" )
       cmd.Parameters.Add( "@name", MySqlDbType.VarChar, 15, "name" )
       da.InsertCommand = cmd

       Return da
     End Function

C# example:

     public static MySqlDataAdapter CreateCustomerAdapter(MySqlConnection conn)
     {
       MySqlDataAdapter da = new MySqlDataAdapter();
       MySqlCommand cmd;
       MySqlParameter parm;
       // Create the SelectCommand.
       cmd = new MySqlCommand("SELECT * FROM mytable WHERE id=@id AND name=@name", conn);
       cmd.Parameters.Add("@id", MySqlDbType.VarChar, 15);
       cmd.Parameters.Add("@name", MySqlDbType.VarChar, 15);
       da.SelectCommand = cmd;
       // Create the InsertCommand.
       cmd = new MySqlCommand("INSERT INTO mytable (id,name) VALUES (@id,@name)", conn);
       cmd.Parameters.Add("@id", MySqlDbType.VarChar, 15, "id" );
       cmd.Parameters.Add("@name", MySqlDbType.VarChar, 15, "name" );

       da.InsertCommand = cmd;
       return da;
     }


File: manual.info,  Node: connector-net-examples-mysqldataadapter-updatecommand,  Next: connector-net-examples-mysqldataadapter-selectcommand,  Prev: connector-net-examples-mysqldataadapter-insertcommand,  Up: connector-net-examples-mysqldataadapter

30.2.3.55 UpdateCommand
.......................

Gets or sets a SQL statement or stored procedure used to updated
records in the data source.

*Value:* A `MySqlCommand' used during
`System.Data.Common.DataAdapter.Update' to update records in the
database with data from the `DataSet'.

During `System.Data.Common.DataAdapter.Update', if this property is not
set and primary key information is present in the `DataSet', the
`UpdateCommand' can be generated automatically if you set the
`SelectCommand' property and use the `MySqlCommandBuilder'.  Then, any
additional commands that you do not set are generated by the
`MySqlCommandBuilder'. This generation logic requires key column
information to be present in the `DataSet'.

When `UpdateCommand' is assigned to a previously created
`MySqlCommand', the `MySqlCommand' is not cloned. The `UpdateCommand'
maintains a reference to the previously created `MySqlCommand' object.

*Note*:

If execution of this command returns rows, these rows may be merged
with the DataSet depending on how you set the
`MySqlCommand.UpdatedRowSource' property of the `MySqlCommand' object.

*Examples*

The following example creates a `MySqlDataAdapter' and sets the
`SelectCommand' and `UpdateCommand' properties. It assumes you have
already created a `MySqlConnection' object.

Visual Basic example:

     Public Shared Function CreateCustomerAdapter(conn As MySqlConnection) As MySqlDataAdapter

       Dim da As MySqlDataAdapter = New MySqlDataAdapter()
       Dim cmd As MySqlCommand
       Dim parm As MySqlParameter
       ' Create the SelectCommand.
       cmd = New MySqlCommand("SELECT * FROM mytable WHERE id=@id AND name=@name", conn)
       cmd.Parameters.Add("@id", MySqlDbType.VarChar, 15)
       cmd.Parameters.Add("@name", MySqlDbType.VarChar, 15)
       da.SelectCommand = cmd
       ' Create the UpdateCommand.
       cmd = New MySqlCommand("UPDATE mytable SET id=@id, name=@name WHERE id=@oldId", conn)
       cmd.Parameters.Add( "@id", MySqlDbType.VarChar, 15, "id" )
       cmd.Parameters.Add( "@name", MySqlDbType.VarChar, 15, "name" )

       parm = cmd.Parameters.Add("@oldId", MySqlDbType.VarChar, 15, "id")
       parm.SourceVersion = DataRowVersion.Original

       da.UpdateCommand = cmd

       Return da
     End Function

C# example:

     public static MySqlDataAdapter CreateCustomerAdapter(MySqlConnection conn)
     {
       MySqlDataAdapter da = new MySqlDataAdapter();
       MySqlCommand cmd;
       MySqlParameter parm;
       // Create the SelectCommand.
       cmd = new MySqlCommand("SELECT * FROM mytable WHERE id=@id AND name=@name", conn);
       cmd.Parameters.Add("@id", MySqlDbType.VarChar, 15);
       cmd.Parameters.Add("@name", MySqlDbType.VarChar, 15);
       da.SelectCommand = cmd;
       // Create the UpdateCommand.
       cmd = new MySqlCommand("UPDATE mytable SET id=@id, name=@name WHERE id=@oldId", conn);
       cmd.Parameters.Add("@id", MySqlDbType.VarChar, 15, "id" );
       cmd.Parameters.Add("@name", MySqlDbType.VarChar, 15, "name" );

       parm = cmd.Parameters.Add( "@oldId", MySqlDbType.VarChar, 15, "id" );
       parm.SourceVersion = DataRowVersion.Original;

       da.UpdateCommand = cmd;
       return da;
     }


File: manual.info,  Node: connector-net-examples-mysqldataadapter-selectcommand,  Prev: connector-net-examples-mysqldataadapter-updatecommand,  Up: connector-net-examples-mysqldataadapter

30.2.3.56 SelectCommand
.......................

Gets or sets a SQL statement or stored procedure used to select records
in the data source.

*Value:* A `MySqlCommand' used during
`System.Data.Common.DbDataAdapter.Fill' to select records from the
database for placement in the `DataSet'.

When `SelectCommand' is assigned to a previously created
`MySqlCommand', the `MySqlCommand' is not cloned. The `SelectCommand'
maintains a reference to the previously created `MySqlCommand' object.

If the `SelectCommand' does not return any rows, no tables are added to
the `DataSet', and no exception is raised.

*Examples*

The following example creates a `MySqlDataAdapter' and sets the
`SelectCommand' and `InsertCommand' properties. It assumes you have
already created a `MySqlConnection' object.

Visual Basic example:

     Public Shared Function CreateCustomerAdapter(conn As MySqlConnection) As MySqlDataAdapter

       Dim da As MySqlDataAdapter = New MySqlDataAdapter()
       Dim cmd As MySqlCommand
       Dim parm As MySqlParameter
       ' Create the SelectCommand.
       cmd = New MySqlCommand("SELECT * FROM mytable WHERE id=@id AND name=@name", conn)
       cmd.Parameters.Add("@id", MySqlDbType.VarChar, 15)
       cmd.Parameters.Add("@name", MySqlDbType.VarChar, 15)
       da.SelectCommand = cmd
       ' Create the InsertCommand.
       cmd = New MySqlCommand("INSERT INTO mytable (id,name) VALUES (@id, @name)", conn)
       cmd.Parameters.Add( "@id", MySqlDbType.VarChar, 15, "id" )
       cmd.Parameters.Add( "@name", MySqlDbType.VarChar, 15, "name" )
       da.InsertCommand = cmd

       Return da
     End Function

C# example:

     public static MySqlDataAdapter CreateCustomerAdapter(MySqlConnection conn)
     {
       MySqlDataAdapter da = new MySqlDataAdapter();
       MySqlCommand cmd;
       MySqlParameter parm;
       // Create the SelectCommand.
       cmd = new MySqlCommand("SELECT * FROM mytable WHERE id=@id AND name=@name", conn);
       cmd.Parameters.Add("@id", MySqlDbType.VarChar, 15);
       cmd.Parameters.Add("@name", MySqlDbType.VarChar, 15);
       da.SelectCommand = cmd;
       // Create the InsertCommand.
       cmd = new MySqlCommand("INSERT INTO mytable (id,name) VALUES (@id,@name)", conn);
       cmd.Parameters.Add("@id", MySqlDbType.VarChar, 15, "id" );
       cmd.Parameters.Add("@name", MySqlDbType.VarChar, 15, "name" );

       da.InsertCommand = cmd;
       return da;
     }


File: manual.info,  Node: connector-net-examples-mysqldatareader,  Next: connector-net-examples-mysqlexception,  Prev: connector-net-examples-mysqldataadapter,  Up: connector-net-examples

30.2.3.57 Using `MySqlDataReader'
.................................

* Menu:

* connector-net-examples-mysqldatareader-getbytes::  GetBytes
* connector-net-examples-mysqldatareader-gettimespan::  GetTimeSpan
* connector-net-examples-mysqldatareader-getdatetime::  GetDateTime
* connector-net-examples-mysqldatareader-getmysqldatetime::  GetMySqlDateTime
* connector-net-examples-mysqldatareader-getstring::  GetString
* connector-net-examples-mysqldatareader-getdecimal::  GetDecimal
* connector-net-examples-mysqldatareader-getdouble::  GetDouble
* connector-net-examples-mysqldatareader-getfloat::  GetFloat
* connector-net-examples-mysqldatareader-getgiud::  GetGiud
* connector-net-examples-mysqldatareader-getint16::  GetInt16
* connector-net-examples-mysqldatareader-getint32::  GetInt32
* connector-net-examples-mysqldatareader-getint64::  GetInt64
* connector-net-examples-mysqldatareader-getuint16::  GetUInt16
* connector-net-examples-mysqldatareader-getuint32::  GetUInt32
* connector-net-examples-mysqldatareader-getuint64::  GetUInt64

To create a `MySQLDataReader', you must call the
`MySqlCommand.ExecuteReader' method of the `MySqlCommand' object,
rather than directly using a constructor.

While the `MySqlDataReader' is in use, the associated `MySqlConnection'
is busy serving the `MySqlDataReader', and no other operations can be
performed on the `MySqlConnection' other than closing it. This is the
case until the `MySqlDataReader.Close' method of the `MySqlDataReader'
is called.

`MySqlDataReader.IsClosed' and `MySqlDataReader.RecordsAffected' are
the only properties that you can call after the `MySqlDataReader' is
closed. Though the `RecordsAffected' property may be accessed at any
time while the `MySqlDataReader' exists, always call `Close' before
returning the value of `RecordsAffected' to ensure an accurate return
value.

For optimal performance, `MySqlDataReader' avoids creating unnecessary
objects or making unnecessary copies of data. As a result, multiple
calls to methods such as `MySqlDataReader.GetValue' return a reference
to the same object. Use caution if you are modifying the underlying
value of the objects returned by methods such as `GetValue'.

*Examples*

The following example creates a `MySqlConnection', a `MySqlCommand',
and a `MySqlDataReader'. The example reads through the data, writing it
out to the console. Finally, the example closes the `MySqlDataReader',
then the `MySqlConnection'.

Visual Basic example:

     Public Sub ReadMyData(myConnString As String)
         Dim mySelectQuery As String = "SELECT OrderID, CustomerID FROM Orders"
         Dim myConnection As New MySqlConnection(myConnString)
         Dim myCommand As New MySqlCommand(mySelectQuery, myConnection)
         myConnection.Open()
         Dim myReader As MySqlDataReader
         myReader = myCommand.ExecuteReader()
         ' Always call Read before accessing data.
         While myReader.Read()
             Console.WriteLine((myReader.GetInt32(0) & ", " & myReader.GetString(1)))
         End While
         ' always call Close when done reading.
         myReader.Close()
         ' Close the connection when done with it.
         myConnection.Close()
     End Sub 'ReadMyData

C# example:

     public void ReadMyData(string myConnString) {
         string mySelectQuery = "SELECT OrderID, CustomerID FROM Orders";
         MySqlConnection myConnection = new MySqlConnection(myConnString);
         MySqlCommand myCommand = new MySqlCommand(mySelectQuery,myConnection);
         myConnection.Open();
         MySqlDataReader myReader;
         myReader = myCommand.ExecuteReader();
         // Always call Read before accessing data.
         while (myReader.Read()) {
            Console.WriteLine(myReader.GetInt32(0) + ", " + myReader.GetString(1));
         }
         // always call Close when done reading.
         myReader.Close();
         // Close the connection when done with it.
         myConnection.Close();
      }


File: manual.info,  Node: connector-net-examples-mysqldatareader-getbytes,  Next: connector-net-examples-mysqldatareader-gettimespan,  Prev: connector-net-examples-mysqldatareader,  Up: connector-net-examples-mysqldatareader

30.2.3.58 GetBytes
..................

`GetBytes' returns the number of available bytes in the field. In most
cases this is the exact length of the field. However, the number
returned may be less than the true length of the field if `GetBytes' has
already been used to obtain bytes from the field. This may be the case,
for example, if the `MySqlDataReader' is reading a large data structure
into a buffer. For more information, see the `SequentialAccess' setting
for `MySqlCommand.CommandBehavior'.

If you pass a buffer that is a null reference (`Nothing' in Visual
Basic), `GetBytes' returns the length of the field in bytes.

No conversions are performed; therefore the data retrieved must already
be a byte array.


File: manual.info,  Node: connector-net-examples-mysqldatareader-gettimespan,  Next: connector-net-examples-mysqldatareader-getdatetime,  Prev: connector-net-examples-mysqldatareader-getbytes,  Up: connector-net-examples-mysqldatareader

30.2.3.59 GetTimeSpan
.....................

Gets the value of the specified column as a `TimeSpan' object.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getdatetime,  Next: connector-net-examples-mysqldatareader-getmysqldatetime,  Prev: connector-net-examples-mysqldatareader-gettimespan,  Up: connector-net-examples-mysqldatareader

30.2.3.60 GetDateTime
.....................

Gets the value of the specified column as a `System.DateTime' object.

*Note*:

MySQL allows date columns to contain the value '0000-00-00' and
datetime columns to contain the value '0000-00-00 00:00:00'. The
DateTime structure cannot contain or represent these values. To read a
datetime value from a column that might contain zero values, use
`GetMySqlDateTime'. The behavior of reading a zero datetime column
using this method is defined by the `ZeroDateTimeBehavior' connection
string option. For more information on this option, please refer to
`MySqlConnection.ConnectionString'.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getmysqldatetime,  Next: connector-net-examples-mysqldatareader-getstring,  Prev: connector-net-examples-mysqldatareader-getdatetime,  Up: connector-net-examples-mysqldatareader

30.2.3.61 GetMySqlDateTime
..........................

Gets the value of the specified column as a
`MySql.Data.Types.MySqlDateTime' object.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getstring,  Next: connector-net-examples-mysqldatareader-getdecimal,  Prev: connector-net-examples-mysqldatareader-getmysqldatetime,  Up: connector-net-examples-mysqldatareader

30.2.3.62 GetString
...................

Gets the value of the specified column as a `String' object.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getdecimal,  Next: connector-net-examples-mysqldatareader-getdouble,  Prev: connector-net-examples-mysqldatareader-getstring,  Up: connector-net-examples-mysqldatareader

30.2.3.63 GetDecimal
....................

Gets the value of the specified column as a `Decimal' object.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getdouble,  Next: connector-net-examples-mysqldatareader-getfloat,  Prev: connector-net-examples-mysqldatareader-getdecimal,  Up: connector-net-examples-mysqldatareader

30.2.3.64 GetDouble
...................

Gets the value of the specified column as a double-precision floating
point number.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getfloat,  Next: connector-net-examples-mysqldatareader-getgiud,  Prev: connector-net-examples-mysqldatareader-getdouble,  Up: connector-net-examples-mysqldatareader

30.2.3.65 GetFloat
..................

Gets the value of the specified column as a single-precision floating
point number.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getgiud,  Next: connector-net-examples-mysqldatareader-getint16,  Prev: connector-net-examples-mysqldatareader-getfloat,  Up: connector-net-examples-mysqldatareader

30.2.3.66 GetGiud
.................

Gets the value of the specified column as a globally-unique identifier
(GUID).

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getint16,  Next: connector-net-examples-mysqldatareader-getint32,  Prev: connector-net-examples-mysqldatareader-getgiud,  Up: connector-net-examples-mysqldatareader

30.2.3.67 GetInt16
..................

Gets the value of the specified column as a 16-bit signed integer.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getint32,  Next: connector-net-examples-mysqldatareader-getint64,  Prev: connector-net-examples-mysqldatareader-getint16,  Up: connector-net-examples-mysqldatareader

30.2.3.68 GetInt32
..................

Gets the value of the specified column as a 32-bit signed integer.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getint64,  Next: connector-net-examples-mysqldatareader-getuint16,  Prev: connector-net-examples-mysqldatareader-getint32,  Up: connector-net-examples-mysqldatareader

30.2.3.69 GetInt64
..................

Gets the value of the specified column as a 64-bit signed integer.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getuint16,  Next: connector-net-examples-mysqldatareader-getuint32,  Prev: connector-net-examples-mysqldatareader-getint64,  Up: connector-net-examples-mysqldatareader

30.2.3.70 GetUInt16
...................

Gets the value of the specified column as a 16-bit unsigned integer.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getuint32,  Next: connector-net-examples-mysqldatareader-getuint64,  Prev: connector-net-examples-mysqldatareader-getuint16,  Up: connector-net-examples-mysqldatareader

30.2.3.71 GetUInt32
...................

Gets the value of the specified column as a 32-bit unsigned integer.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqldatareader-getuint64,  Prev: connector-net-examples-mysqldatareader-getuint32,  Up: connector-net-examples-mysqldatareader

30.2.3.72 GetUInt64
...................

Gets the value of the specified column as a 64-bit unsigned integer.

*Parameters:* The zero-based column ordinal.

*Returns:* The value of the specified column.


File: manual.info,  Node: connector-net-examples-mysqlexception,  Next: connector-net-examples-mysqlparameter,  Prev: connector-net-examples-mysqldatareader,  Up: connector-net-examples

30.2.3.73 Using `MySqlException'
................................

This class is created whenever the MySQL Data Provider encounters an
error generated from the server.

Any open connections are not automatically closed when an exception is
thrown. If the client application determines that the exception is
fatal, it should close any open `MySqlDataReader' objects or
`MySqlConnection' objects.

*Examples*

The following example generates a `MySqlException' due to a missing
server, and then displays the exception.

Visual Basic example:

     Public Sub ShowException()
          Dim mySelectQuery As String = "SELECT column1 FROM table1"
          Dim myConnection As New MySqlConnection ("Data Source=localhost;Database=Sample;")
          Dim myCommand As New MySqlCommand(mySelectQuery, myConnection)
          Try
              myCommand.Connection.Open()
          Catch e As MySqlException
         MessageBox.Show( e.Message )
          End Try
      End Sub

C# example:

     public void ShowException()
     {
        string mySelectQuery = "SELECT column1 FROM table1";
        MySqlConnection myConnection =
           new MySqlConnection("Data Source=localhost;Database=Sample;");
        MySqlCommand myCommand = new MySqlCommand(mySelectQuery,myConnection);
        try
        {
           myCommand.Connection.Open();
        }
        catch (MySqlException e)
        {
         MessageBox.Show( e.Message );
        }
     }


File: manual.info,  Node: connector-net-examples-mysqlparameter,  Next: connector-net-examples-mysqlparametercollection,  Prev: connector-net-examples-mysqlexception,  Up: connector-net-examples

30.2.3.74 Using `MySqlParameter'
................................

Parameter names are not case sensitive.

*Examples*

The following example creates multiple instances of `MySqlParameter'
through the `MySqlParameterCollection' collection within the
`MySqlDataAdapter'. These parameters are used to select data from the
data source and place the data in the `DataSet'. This example assumes
that a `DataSet' and a `MySqlDataAdapter' have already been created
with the appropriate schema, commands, and connection.

Visual Basic example:

     Public Sub AddSqlParameters()
         ' ...
         ' create myDataSet and myDataAdapter
         ' ...
         myDataAdapter.SelectCommand.Parameters.Add("@CategoryName", MySqlDbType.VarChar, 80).Value = "toasters"
         myDataAdapter.SelectCommand.Parameters.Add("@SerialNum", MySqlDbType.Long).Value = 239

         myDataAdapter.Fill(myDataSet)
     End Sub 'AddSqlParameters

C# example:

     public void AddSqlParameters()
     {
     // ...
     // create myDataSet and myDataAdapter
     // ...
       myDataAdapter.SelectCommand.Parameters.Add("@CategoryName", MySqlDbType.VarChar, 80).Value = "toasters";
       myDataAdapter.SelectCommand.Parameters.Add("@SerialNum", MySqlDbType.Long).Value = 239;
       myDataAdapter.Fill(myDataSet);
     }


File: manual.info,  Node: connector-net-examples-mysqlparametercollection,  Next: connector-net-examples-mysqltransaction,  Prev: connector-net-examples-mysqlparameter,  Up: connector-net-examples

30.2.3.75 Using `MySqlParameterCollection'
..........................................

The number of the parameters in the collection must be equal to the
number of parameter placeholders within the command text, or an
exception will be generated.

*Examples*

The following example creates multiple instances of `MySqlParameter'
through the `MySqlParameterCollection' collection within the
`MySqlDataAdapter'. These parameters are used to select data within the
data source and place the data in the `DataSet'. This code assumes that
a `DataSet' and a `MySqlDataAdapter' have already been created with the
appropriate schema, commands, and connection.

Visual Basic example:

     Public Sub AddParameters()
         ' ...
         ' create myDataSet and myDataAdapter
         ' ...
         myDataAdapter.SelectCommand.Parameters.Add("@CategoryName", MySqlDbType.VarChar, 80).Value = "toasters"
         myDataAdapter.SelectCommand.Parameters.Add("@SerialNum", MySqlDbType.Long).Value = 239

         myDataAdapter.Fill(myDataSet)
     End Sub 'AddSqlParameters

C# example:

     public void AddSqlParameters()
     {
     // ...
     // create myDataSet and myDataAdapter
     // ...
       myDataAdapter.SelectCommand.Parameters.Add("@CategoryName", MySqlDbType.VarChar, 80).Value = "toasters";
       myDataAdapter.SelectCommand.Parameters.Add("@SerialNum", MySqlDbType.Long).Value = 239;
       myDataAdapter.Fill(myDataSet);
     }


File: manual.info,  Node: connector-net-examples-mysqltransaction,  Prev: connector-net-examples-mysqlparametercollection,  Up: connector-net-examples

30.2.3.76 Using `MySqlTransaction'
..................................

* Menu:

* connector-net-examples-mysqltransaction-rollback::  Rollback
* connector-net-examples-mysqltransaction-commit::  Commit

Represents a SQL transaction to be made in a MySQL database.  This
class cannot be inherited.

The application creates a `MySqlTransaction' object by calling
`MySqlConnection.BeginTransaction' on the `MySqlConnection' object. All
subsequent operations associated with the transaction (for example,
committing or aborting the transaction), are performed on the
`MySqlTransaction' object.

*Note*:

Once you have started a transaction on a connection all subsequent
commands on that connection are applied within the scope of the
transaction. You cannot execute an SQL statement on the same connection
outside of the transaction scope. If you need to do this while
executing statements that are part of a transaction, open a second a
connection to be used for execution the non-transaction statements.

*Examples*

The following example creates a `MySqlConnection' and a
`MySqlTransaction'. It also demonstrates how to use the
`MySqlConnection.BeginTransaction', `MySqlTransaction.Commit', and
`MySqlTransaction.Rollback' methods.

Visual Basic example:

     Public Sub RunTransaction(myConnString As String)
         Dim myConnection As New MySqlConnection(myConnString)
         myConnection.Open()

         Dim myCommand As MySqlCommand = myConnection.CreateCommand()
         Dim myTrans As MySqlTransaction

         ' Start a local transaction
         myTrans = myConnection.BeginTransaction()
         ' Must assign both transaction object and connection
         ' to Command object for a pending local transaction
         myCommand.Connection = myConnection
         myCommand.Transaction = myTrans

         Try
           myCommand.CommandText = "Insert into Region (RegionID, RegionDescription) VALUES (100, 'Description')"
           myCommand.ExecuteNonQuery()
           myCommand.CommandText = "Insert into Region (RegionID, RegionDescription) VALUES (101, 'Description')"
           myCommand.ExecuteNonQuery()
           myTrans.Commit()
           Console.WriteLine("Both records are written to database.")
         Catch e As Exception
           Try
             myTrans.Rollback()
           Catch ex As MySqlException
             If Not myTrans.Connection Is Nothing Then
               Console.WriteLine("An exception of type " & ex.GetType().ToString() & _
                                 " was encountered while attempting to roll back the transaction.")
             End If
           End Try

           Console.WriteLine("An exception of type " & e.GetType().ToString() & _
                           "was encountered while inserting the data.")
           Console.WriteLine("Neither record was written to database.")
         Finally
           myConnection.Close()
         End Try
     End Sub 'RunTransaction

C# example:

     public void RunTransaction(string myConnString)
      {
         MySqlConnection myConnection = new MySqlConnection(myConnString);
         myConnection.Open();
         MySqlCommand myCommand = myConnection.CreateCommand();
         MySqlTransaction myTrans;
         // Start a local transaction
         myTrans = myConnection.BeginTransaction();
         // Must assign both transaction object and connection
         // to Command object for a pending local transaction
         myCommand.Connection = myConnection;
         myCommand.Transaction = myTrans;
         try
         {
           myCommand.CommandText = "Insert into Region (RegionID, RegionDescription) VALUES (100, 'Description')";
           myCommand.ExecuteNonQuery();
           myCommand.CommandText = "Insert into Region (RegionID, RegionDescription) VALUES (101, 'Description')";
           myCommand.ExecuteNonQuery();
           myTrans.Commit();
           Console.WriteLine("Both records are written to database.");
         }
         catch(Exception e)
         {
           try
           {
             myTrans.Rollback();
           }
           catch (MySqlException ex)
           {
             if (myTrans.Connection != null)
             {
               Console.WriteLine("An exception of type " + ex.GetType() +
                                 " was encountered while attempting to roll back the transaction.");
             }
           }

           Console.WriteLine("An exception of type " + e.GetType() +
                             " was encountered while inserting the data.");
           Console.WriteLine("Neither record was written to database.");
         }
         finally
         {
           myConnection.Close();
         }
     }


File: manual.info,  Node: connector-net-examples-mysqltransaction-rollback,  Next: connector-net-examples-mysqltransaction-commit,  Prev: connector-net-examples-mysqltransaction,  Up: connector-net-examples-mysqltransaction

30.2.3.77 Rollback
..................

Rolls back a transaction from a pending state.

The Rollback method is equivalent to the MySQL statement ROLLBACK. The
transaction can only be rolled back from a pending state (after
BeginTransaction has been called, but before Commit is called).

*Examples*

The following example creates `MySqlConnection' and a
`MySqlTransaction'. It also demonstrates how to use the
`MySqlConnection.BeginTransaction', `Commit', and `Rollback' methods.

Visual Basic example:

     Public Sub RunSqlTransaction(myConnString As String)
         Dim myConnection As New MySqlConnection(myConnString)
         myConnection.Open()

         Dim myCommand As MySqlCommand = myConnection.CreateCommand()
         Dim myTrans As MySqlTransaction

         ' Start a local transaction
         myTrans = myConnection.BeginTransaction()

         ' Must assign both transaction object and connection
         ' to Command object for a pending local transaction
         myCommand.Connection = myConnection
         myCommand.Transaction = myTrans

         Try
           myCommand.CommandText = "Insert into mytable (id, desc) VALUES (100, 'Description')"
           myCommand.ExecuteNonQuery()
           myCommand.CommandText = "Insert into mytable (id, desc) VALUES (101, 'Description')"
           myCommand.ExecuteNonQuery()
           myTrans.Commit()
           Console.WriteLine("Success.")
         Catch e As Exception
           Try
             myTrans.Rollback()
           Catch ex As MySqlException
             If Not myTrans.Connection Is Nothing Then
               Console.WriteLine("An exception of type " & ex.GetType().ToString() & _
                                 " was encountered while attempting to roll back the transaction.")
             End If
           End Try

           Console.WriteLine("An exception of type " & e.GetType().ToString() & _
                           "was encountered while inserting the data.")
           Console.WriteLine("Neither record was written to database.")
         Finally
           myConnection.Close()
         End Try
     End Sub

C# example:

     public void RunSqlTransaction(string myConnString)
      {
         MySqlConnection myConnection = new MySqlConnection(myConnString);
         myConnection.Open();
         MySqlCommand myCommand = myConnection.CreateCommand();
         MySqlTransaction myTrans;
         // Start a local transaction
         myTrans = myConnection.BeginTransaction();
         // Must assign both transaction object and connection
         // to Command object for a pending local transaction
         myCommand.Connection = myConnection;
         myCommand.Transaction = myTrans;
         try
         {
           myCommand.CommandText = "Insert into mytable (id, desc) VALUES (100, 'Description')";
           myCommand.ExecuteNonQuery();
           myCommand.CommandText = "Insert into mytable (id, desc) VALUES (101, 'Description')";
           myCommand.ExecuteNonQuery();
           myTrans.Commit();
           Console.WriteLine("Both records are written to database.");
         }
         catch(Exception e)
         {
           try
           {
             myTrans.Rollback();
           }
           catch (MySqlException ex)
           {
             if (myTrans.Connection != null)
             {
               Console.WriteLine("An exception of type " + ex.GetType() +
                                 " was encountered while attempting to roll back the transaction.");
             }
           }

           Console.WriteLine("An exception of type " + e.GetType() +
                             " was encountered while inserting the data.");
           Console.WriteLine("Neither record was written to database.");
         }
         finally
         {
           myConnection.Close();
         }
     }


File: manual.info,  Node: connector-net-examples-mysqltransaction-commit,  Prev: connector-net-examples-mysqltransaction-rollback,  Up: connector-net-examples-mysqltransaction

30.2.3.78 Commit
................

Commits the database transaction.

The `Commit' method is equivalent to the MySQL SQL statement COMMIT.

*Examples*

The following example creates `MySqlConnection' and a
`MySqlTransaction'. It also demonstrates how to use the
`MySqlConnection.BeginTransaction', `Commit', and `Rollback' methods.

Visual Basic example:

     Public Sub RunSqlTransaction(myConnString As String)
         Dim myConnection As New MySqlConnection(myConnString)
         myConnection.Open()

         Dim myCommand As MySqlCommand = myConnection.CreateCommand()
         Dim myTrans As MySqlTransaction

         ' Start a local transaction
         myTrans = myConnection.BeginTransaction()

         ' Must assign both transaction object and connection
         ' to Command object for a pending local transaction
         myCommand.Connection = myConnection
         myCommand.Transaction = myTrans

         Try
           myCommand.CommandText = "Insert into mytable (id, desc) VALUES (100, 'Description')"
           myCommand.ExecuteNonQuery()
           myCommand.CommandText = "Insert into mytable (id, desc) VALUES (101, 'Description')"
           myCommand.ExecuteNonQuery()
           myTrans.Commit()
           Console.WriteLine("Success.")
         Catch e As Exception
           Try
             myTrans.Rollback()
           Catch ex As MySqlException
             If Not myTrans.Connection Is Nothing Then
               Console.WriteLine("An exception of type " & ex.GetType().ToString() & _
                                 " was encountered while attempting to roll back the transaction.")
             End If
           End Try

           Console.WriteLine("An exception of type " & e.GetType().ToString() & _
                           "was encountered while inserting the data.")
           Console.WriteLine("Neither record was written to database.")
         Finally
           myConnection.Close()
         End Try
     End Sub

C# example:

     public void RunSqlTransaction(string myConnString)
      {
         MySqlConnection myConnection = new MySqlConnection(myConnString);
         myConnection.Open();
         MySqlCommand myCommand = myConnection.CreateCommand();
         MySqlTransaction myTrans;
         // Start a local transaction
         myTrans = myConnection.BeginTransaction();
         // Must assign both transaction object and connection
         // to Command object for a pending local transaction
         myCommand.Connection = myConnection;
         myCommand.Transaction = myTrans;
         try
         {
           myCommand.CommandText = "Insert into mytable (id, desc) VALUES (100, 'Description')";
           myCommand.ExecuteNonQuery();
           myCommand.CommandText = "Insert into mytable (id, desc) VALUES (101, 'Description')";
           myCommand.ExecuteNonQuery();
           myTrans.Commit();
           Console.WriteLine("Both records are written to database.");
         }
         catch(Exception e)
         {
           try
           {
             myTrans.Rollback();
           }
           catch (MySqlException ex)
           {
             if (myTrans.Connection != null)
             {
               Console.WriteLine("An exception of type " + ex.GetType() +
                                 " was encountered while attempting to roll back the transaction.");
             }
           }

           Console.WriteLine("An exception of type " + e.GetType() +
                             " was encountered while inserting the data.");
           Console.WriteLine("Neither record was written to database.");
         }
         finally
         {
           myConnection.Close();
         }
     }


File: manual.info,  Node: connector-net-ref,  Next: connector-net-using,  Prev: connector-net-examples,  Up: connector-net

30.2.4 Connector/NET Reference
------------------------------

* Menu:

* connector-net-ref-mysqlclient::  `MySql.Data.MySqlClient'
* connector-net-ref-types::      `MySql.Data.Types'

This section of the manual contains a complete reference to the
Connector/NET ADO.NET component, automatically generated from the
embedded documentation.


File: manual.info,  Node: connector-net-ref-mysqlclient,  Next: connector-net-ref-types,  Prev: connector-net-ref,  Up: connector-net-ref

30.2.4.1 `MySql.Data.MySqlClient'
.................................

* Menu:

* connector-net-ref-mysqlclienthierarchy::  `MySql.Data.MySqlClientHierarchy'
* connector-net-ref-mysqlclient-mysqlcommand::  `MySqlCommand' Class
* connector-net-ref-mysqlclient-mysqlcommandbuilder::  `MySqlCommandBuilder' Class
* connector-net-ref-mysqlclient-mysqlexception::  `MySqlException' Class
* connector-net-ref-mysqlclient-mysqlhelper::  `MySqlHelper' Class
* connector-net-ref-mysqlclient-mysqlerrorcode::  `MySqlErrorCode' Enumeration

*Note Namespace hierarchy: connector-net-ref-mysqlclienthierarchy.

*Classes*

*Class*                              *Description*
*Note MySqlCommand:                  
connector-net-ref-mysqlclient-mysqlcommand.
*Note MySqlCommandBuilder:           
connector-net-ref-mysqlclient-mysqlcommandbuilder.
*Note MySqlConnection:               
connector-net-ref-mysqlclient-mysqlconnection.
*Note MySqlDataAdapter:              
connector-net-ref-mysqlclient-mysqldataadapter.
*Note MySqlDataReader:               Provides a means of reading a
connector-net-ref-mysqlclient-mysqldatareader.forward-only stream of rows from a
                                     MySQL database. This class cannot
                                     be inherited.
*Note MySqlError:                    Collection of error codes that can
connector-net-ref-mysqlclient-mysqlerror.be returned by the server
*Note MySqlException:                The exception that is thrown when
connector-net-ref-mysqlclient-mysqlexception.MySQL returns an error. This class
                                     cannot be inherited.
*Note MySqlHelper:                   Helper class that makes it easier
connector-net-ref-mysqlclient-mysqlhelper.to work with the provider.
*Note MySqlInfoMessageEventArgs:     Provides data for the InfoMessage
connector-net-ref-mysqlclient-mysqlinfomessageeventargs.event. This class cannot be
                                     inherited.
*Note MySqlParameter:                Represents a parameter to a *Note
connector-net-ref-mysqlclient-mysqlparameter.MySqlCommand:
                                     connector-net-ref-mysqlclient-mysqlcommand
                                     , and optionally, its mapping to
                                     DataSetcolumns. This class cannot
                                     be inherited.
*Note MySqlParameterCollection:      Represents a collection of
connector-net-ref-mysqlclient-mysqlparametercollection.parameters relevant to a *Note
                                     MySqlCommand:
                                     connector-net-ref-mysqlclient-mysqlcommand.
                                     as well as their respective
                                     mappings to columns in a DataSet.
                                     This class cannot be inherited.
*Note MySqlRowUpdatedEventArgs:      Provides data for the RowUpdated
connector-net-ref-mysqlclient-mysqlrowupdatedeventargs.event. This class cannot be
                                     inherited.
*Note MySqlRowUpdatingEventArgs:     Provides data for the RowUpdating
connector-net-ref-mysqlclient-mysqlrowupdatingeventargs.event. This class cannot be
                                     inherited.
*Note MySqlTransaction:              
connector-net-ref-mysqlclient-mysqltransaction.

*Delegates*

*Delegate*                           *Description*
*Note MySqlInfoMessageEventHandler:  Represents the method that will
connector-net-ref-mysqlclient-mysqlinfomessageeventhandler.handle the *Note InfoMessage:
                                     connector-net-ref-mysqlclient-mysqlconnection-infomessage.
                                     event of a *Note MySqlConnection:
                                     connector-net-ref-mysqlclient-mysqlconnection.
*Note MySqlRowUpdatedEventHandler:   Represents the method that will
connector-net-ref-mysqlclient-mysqlrowupdatedeventhandler.handle the RowUpdatedevent of a
                                     *Note MySqlDataAdapter:
                                     connector-net-ref-mysqlclient-mysqldataadapter
                                     .
*Note MySqlRowUpdatingEventHandler:  Represents the method that will
connector-net-ref-mysqlclient-mysqlrowupdatingeventhandler.handle the RowUpdatingevent of a
                                     *Note MySqlDataAdapter:
                                     connector-net-ref-mysqlclient-mysqldataadapter
                                     .

*Enumerations*

*Enumeration*                        *Description*
*Note MySqlDbType:                   Specifies MySQL specific data type
connector-net-ref-mysqlclient-mysqldbtype.of a field, property, for use in a
                                     *Note MySqlParameter:
                                     connector-net-ref-mysqlclient-mysqlparameter
                                     .
*Note MySqlErrorCode:                
connector-net-ref-mysqlclient-mysqlerrorcode.


File: manual.info,  Node: connector-net-ref-mysqlclienthierarchy,  Next: connector-net-ref-mysqlclient-mysqlcommand,  Prev: connector-net-ref-mysqlclient,  Up: connector-net-ref-mysqlclient

30.2.4.2 `MySql.Data.MySqlClientHierarchy'
..........................................

*See Also*

*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilder,  Prev: connector-net-ref-mysqlclienthierarchy,  Up: connector-net-ref-mysqlclient

30.2.4.3 `MySqlCommand' Class
.............................

* Menu:

* connector-net-ref-mysqlclient-mysqlcommandmembers::  `MySqlCommand' Members

For a list of all members of this type, see *Note MySqlCommand Members:
connector-net-ref-mysqlclient-mysqlcommandmembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlCommand_
       Inherits Component_
       Implements IDbCommand, ICloneable

*Syntax: C#*

     public sealed class MySqlCommand : Component, IDbCommand, ICloneable

*Thread Safety*

Public static (Shared in Visual Basic) members of this type are safe
for multithreaded operations. Instance members are not guaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlCommand Members:
connector-net-ref-mysqlclient-mysqlcommandmembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandmembers,  Prev: connector-net-ref-mysqlclient-mysqlcommand,  Up: connector-net-ref-mysqlclient-mysqlcommand

30.2.4.4 `MySqlCommand' Members
...............................

* Menu:

* connector-net-ref-mysqlclient-mysqlcommandconstructor::  `MySqlCommand' Constructor
* connector-net-ref-mysqlclient-mysqlcommand-commandtext::  CommandText Property
* connector-net-ref-mysqlclient-mysqlcommand-commandtimeout::  CommandTimeout Property
* connector-net-ref-mysqlclient-mysqlcommand-commandtype::  CommandType Property
* connector-net-ref-mysqlclient-mysqlcommand-connection::  Connection Property
* connector-net-ref-mysqlclient-mysqlcommand-isprepared::  IsPrepared Property
* connector-net-ref-mysqlclient-mysqlcommand-parameters::  Parameters Property
* connector-net-ref-mysqlclient-mysqlcommand-transaction::  Transaction Property
* connector-net-ref-mysqlclient-mysqlcommand-updatedrowsource::  UpdatedRowSource Property
* connector-net-ref-mysqlclient-mysqlcommand-cancel::  `MySqlCommand.Cancel' Method
* connector-net-ref-mysqlclient-mysqlcommand-createparameter::  `MySqlCommand.CreateParameter' Method
* connector-net-ref-mysqlclient-mysqlcommand-executenonquery::  `MySqlCommand.ExecuteNonQuery' Method
* connector-net-ref-mysqlclient-mysqlcommand-executereader-overloads::  ExecuteReader Method
* connector-net-ref-mysqlclient-mysqlcommand-executescalar::  `MySqlCommand.ExecuteScalar' Method
* connector-net-ref-mysqlclient-mysqlcommand-prepare::  `MySqlCommand.Prepare' Method

*Note MySqlCommand overview: connector-net-ref-mysqlclient-mysqlcommand.

*Public Instance Constructors*

*Note MySqlCommand:                  Overloaded. Initializes a new
connector-net-ref-mysqlclient-mysqlcommandconstructor.instance of the MySqlCommand class.

*Public Instance Properties*

*Note CommandText:                   
connector-net-ref-mysqlclient-mysqlcommand-commandtext.
*Note CommandTimeout:                
connector-net-ref-mysqlclient-mysqlcommand-commandtimeout.
*Note CommandType:                   
connector-net-ref-mysqlclient-mysqlcommand-commandtype.
*Note Connection:                    
connector-net-ref-mysqlclient-mysqlcommand-connection.
Container(inherited from Component)  Gets the IContainerthat contains
                                     the Component.
*Note IsPrepared:                    
connector-net-ref-mysqlclient-mysqlcommand-isprepared.
*Note Parameters:                    
connector-net-ref-mysqlclient-mysqlcommand-parameters.
Site(inherited from Component)       Gets or sets the ISiteof the
                                     Component.
*Note Transaction:                   
connector-net-ref-mysqlclient-mysqlcommand-transaction.
*Note UpdatedRowSource:              
connector-net-ref-mysqlclient-mysqlcommand-updatedrowsource.

*Public Instance Methods*

*Note Cancel:                        Attempts to cancel the execution of
connector-net-ref-mysqlclient-mysqlcommand-cancel.a MySqlCommand. This operation is
                                     not supported.
CreateObjRef(inherited from          Creates an object that contains all
MarshalByRefObject)                  the relevant information required to
                                     generate a proxy used to
                                     communicate with a remote object.
*Note CreateParameter:               Creates a new instance of a *Note
connector-net-ref-mysqlclient-mysqlcommand-createparameter.MySqlParameter:
                                     connector-net-ref-mysqlclient-mysqlparameter.
                                     object.
Dispose(inherited from Component)    Releases all resources used by the
                                     Component.
Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
*Note ExecuteNonQuery:               
connector-net-ref-mysqlclient-mysqlcommand-executenonquery.
*Note ExecuteReader:                 Overloaded.
connector-net-ref-mysqlclient-mysqlcommand-executereader-overloads.
*Note ExecuteScalar:                 
connector-net-ref-mysqlclient-mysqlcommand-executescalar.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetLifetimeService(inherited from    Retrieves the current lifetime
MarshalByRefObject)                  service object that controls the
                                     lifetime policy for this instance.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
InitializeLifetimeService(inherited  Obtains a lifetime service object
from MarshalByRefObject)             to control the lifetime policy for
                                     this instance.
*Note Prepare:                       
connector-net-ref-mysqlclient-mysqlcommand-prepare.
ToString(inherited from Component)   Returns a Stringcontaining the name
                                     of the Component, if any. This
                                     method should not be overridden.

*Public Instance Events*

Disposed(inherited from Component)   Adds an event handler to listen to
                                     the Disposedevent on the component.

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandconstructor,  Next: connector-net-ref-mysqlclient-mysqlcommand-commandtext,  Prev: connector-net-ref-mysqlclient-mysqlcommandmembers,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

30.2.4.5 `MySqlCommand' Constructor
...................................

* Menu:

* connector-net-ref-mysqlclient-mysqlcommandconstructor1::  `MySqlCommand' Constructor ()
* connector-net-ref-mysqlclient-mysqlcommandconstructor2::  `MySqlCommand' Constructor (String)
* connector-net-ref-mysqlclient-mysqlcommandconstructor3::  `MySqlCommand' Constructor
* connector-net-ref-mysqlclient-mysqlcommandconstructor4::  `MySqlCommand' Constructor

Initializes a new instance of the *Note MySqlCommand:
connector-net-ref-mysqlclient-mysqlcommand.  class.

*Overload List*

Initializes a new instance of the *Note MySqlCommand:
connector-net-ref-mysqlclient-mysqlcommand.  class.

   * *Note public MySqlCommand();:
     connector-net-ref-mysqlclient-mysqlcommandconstructor1.

   * *Note public MySqlCommand(string);:
     connector-net-ref-mysqlclient-mysqlcommandconstructor2.

   * *Note public MySqlCommand(string:
     (MySqlConnection);)connector-net-ref-mysqlclient-mysqlcommandconstructor3.

   * *Note public MySqlCommand(string:
     (MySqlConnection)connector-net-ref-mysqlclient-mysqlcommandconstructor4.

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandconstructor1,  Next: connector-net-ref-mysqlclient-mysqlcommandconstructor2,  Prev: connector-net-ref-mysqlclient-mysqlcommandconstructor,  Up: connector-net-ref-mysqlclient-mysqlcommandconstructor

30.2.4.6 `MySqlCommand' Constructor ()
......................................

Initializes a new instance of the *Note MySqlCommand:
connector-net-ref-mysqlclient-mysqlcommand.  class.

*Syntax: Visual Basic*

     Overloads Public Sub New()

*Syntax: C#*

     public MySqlCommand();

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlCommand Constructor Overload List:
connector-net-ref-mysqlclient-mysqlcommandconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandconstructor2,  Next: connector-net-ref-mysqlclient-mysqlcommandconstructor3,  Prev: connector-net-ref-mysqlclient-mysqlcommandconstructor1,  Up: connector-net-ref-mysqlclient-mysqlcommandconstructor

30.2.4.7 `MySqlCommand' Constructor (String)
............................................

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal cmdText As String _
     )

*Syntax: C#*

     public MySqlCommand(
     stringcmdText
     );

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlCommand Constructor Overload List:
connector-net-ref-mysqlclient-mysqlcommandconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandconstructor3,  Next: connector-net-ref-mysqlclient-mysqlcommandconstructor4,  Prev: connector-net-ref-mysqlclient-mysqlcommandconstructor2,  Up: connector-net-ref-mysqlclient-mysqlcommandconstructor

30.2.4.8 `MySqlCommand' Constructor
...................................

* Menu:

* connector-net-ref-mysqlclient-mysqlconnection::  `MySqlConnection' Class

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal cmdText As String, _
        ByVal connection As MySqlConnection _
     )

*Syntax: C#*

     public MySqlCommand(
     stringcmdText,
     MySqlConnectionconnection
     );

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlCommand Constructor Overload List:
connector-net-ref-mysqlclient-mysqlcommandconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection,  Prev: connector-net-ref-mysqlclient-mysqlcommandconstructor3,  Up: connector-net-ref-mysqlclient-mysqlcommandconstructor3

30.2.4.9 `MySqlConnection' Class
................................

* Menu:

* connector-net-ref-mysqlclient-mysqlconnectionmembers::  `MySqlConnection' Members

For a list of all members of this type, see *Note MySqlConnection
Members: connector-net-ref-mysqlclient-mysqlconnectionmembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlConnection_
       Inherits Component_
       Implements IDbConnection, ICloneable

*Syntax: C#*

     public sealed class MySqlConnection : Component, IDbConnection, ICloneable

*Thread Safety*

Public static (Shared in Visual Basic) members of this type are safe
for multithreaded operations. Instance members are not guaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlConnection Members:
connector-net-ref-mysqlclient-mysqlconnectionmembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnectionmembers,  Prev: connector-net-ref-mysqlclient-mysqlconnection,  Up: connector-net-ref-mysqlclient-mysqlconnection

30.2.4.10 `MySqlConnection' Members
...................................

* Menu:

* connector-net-ref-mysqlclient-mysqlconnectionconstructor::  `MySqlConnection' Constructor
* connector-net-ref-mysqlclient-mysqlconnection-connectionstring::  ConnectionString Property
* connector-net-ref-mysqlclient-mysqlconnection-connectiontimeout::  ConnectionTimeout Property
* connector-net-ref-mysqlclient-mysqlconnection-database::  Database Property
* connector-net-ref-mysqlclient-mysqlconnection-datasource::  DataSource Property
* connector-net-ref-mysqlclient-mysqlconnection-serverthread::  ServerThread Property
* connector-net-ref-mysqlclient-mysqlconnection-serverversion::  ServerVersion Property
* connector-net-ref-mysqlclient-mysqlconnection-state::  State Property
* connector-net-ref-mysqlclient-mysqlconnection-usecompression::  UseCompression Property
* connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overloads::  BeginTransaction Method
* connector-net-ref-mysqlclient-mysqlconnection-changedatabase::  `MySqlConnection.ChangeDatabase' Method
* connector-net-ref-mysqlclient-mysqlconnection-close::  `MySqlConnection.Close' Method
* connector-net-ref-mysqlclient-mysqlconnection-createcommand::  `MySqlConnection.CreateCommand' Method
* connector-net-ref-mysqlclient-mysqlconnection-open::  `MySqlConnection.Open' Method
* connector-net-ref-mysqlclient-mysqlconnection-ping::  `MySqlConnection.Ping' Method
* connector-net-ref-mysqlclient-mysqlconnection-infomessage::  `MySqlConnection.InfoMessage' Event
* connector-net-ref-mysqlclient-mysqlconnection-statechange::  `MySqlConnection.StateChange' Event

*Note MySqlConnection overview:
connector-net-ref-mysqlclient-mysqlconnection.

*Public Instance Constructors*

*Note MySqlConnection:               Overloaded. Initializes a new
connector-net-ref-mysqlclient-mysqlconnectionconstructor.instance of the MySqlConnection
                                     class.

*Public Instance Properties*

*Note ConnectionString:              
connector-net-ref-mysqlclient-mysqlconnection-connectionstring.
*Note ConnectionTimeout:             
connector-net-ref-mysqlclient-mysqlconnection-connectiontimeout.
Container(inherited from Component)  Gets the IContainerthat contains
                                     the Component.
*Note Database:                      
connector-net-ref-mysqlclient-mysqlconnection-database.
*Note DataSource:                    Gets the name of the MySQL server
connector-net-ref-mysqlclient-mysqlconnection-datasource.to which to connect.
*Note ServerThread:                  Returns the id of the server thread
connector-net-ref-mysqlclient-mysqlconnection-serverthread.this connection is executing on
*Note ServerVersion:                 
connector-net-ref-mysqlclient-mysqlconnection-serverversion.
Site(inherited from Component)       Gets or sets the ISiteof the
                                     Component.
*Note State:                         
connector-net-ref-mysqlclient-mysqlconnection-state.
*Note UseCompression:                Indicates if this connection should
connector-net-ref-mysqlclient-mysqlconnection-usecompression.use compression when communicating
                                     with the server.

*Public Instance Methods*

*Note BeginTransaction:              Overloaded.
connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overloads.
*Note ChangeDatabase:                
connector-net-ref-mysqlclient-mysqlconnection-changedatabase.
*Note Close:                         
connector-net-ref-mysqlclient-mysqlconnection-close.
*Note CreateCommand:                 
connector-net-ref-mysqlclient-mysqlconnection-createcommand.
CreateObjRef(inherited from          Creates an object that contains all
MarshalByRefObject)                  the relevant information required to
                                     generate a proxy used to
                                     communicate with a remote object.
Dispose(inherited from Component)    Releases all resources used by the
                                     Component.
Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetLifetimeService(inherited from    Retrieves the current lifetime
MarshalByRefObject)                  service object that controls the
                                     lifetime policy for this instance.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
InitializeLifetimeService(inherited  Obtains a lifetime service object
from MarshalByRefObject)             to control the lifetime policy for
                                     this instance.
*Note Open:                          
connector-net-ref-mysqlclient-mysqlconnection-open.
*Note Ping:                          Ping
connector-net-ref-mysqlclient-mysqlconnection-ping.
ToString(inherited from Component)   Returns a Stringcontaining the name
                                     of the Component, if any. This
                                     method should not be overridden.

*Public Instance Events*

Disposed(inherited from Component)   Adds an event handler to listen to
                                     the Disposedevent on the component.
*Note InfoMessage:                   
connector-net-ref-mysqlclient-mysqlconnection-infomessage.
*Note StateChange:                   
connector-net-ref-mysqlclient-mysqlconnection-statechange.

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnectionconstructor,  Next: connector-net-ref-mysqlclient-mysqlconnection-connectionstring,  Prev: connector-net-ref-mysqlclient-mysqlconnectionmembers,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

30.2.4.11 `MySqlConnection' Constructor
.......................................

* Menu:

* connector-net-ref-mysqlclient-mysqlconnectionconstructor1::  `MySqlConnection' Constructor
* connector-net-ref-mysqlclient-mysqlconnectionconstructor2::  `MySqlConnection' Constructor

Initializes a new instance of the *Note MySqlConnection:
connector-net-ref-mysqlclient-mysqlconnection.  class.

*Overload List*

Initializes a new instance of the *Note MySqlConnection:
connector-net-ref-mysqlclient-mysqlconnection.  class.

   * *Note public MySqlConnection();:
     connector-net-ref-mysqlclient-mysqlconnectionconstructor1.

   * *Note public MySqlConnection(string);:
     connector-net-ref-mysqlclient-mysqlconnectionconstructor2.

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnectionconstructor1,  Next: connector-net-ref-mysqlclient-mysqlconnectionconstructor2,  Prev: connector-net-ref-mysqlclient-mysqlconnectionconstructor,  Up: connector-net-ref-mysqlclient-mysqlconnectionconstructor

30.2.4.12 `MySqlConnection' Constructor
.......................................

Initializes a new instance of the *Note MySqlConnection:
connector-net-ref-mysqlclient-mysqlconnection.  class.

*Syntax: Visual Basic*

     Overloads Public Sub New()

*Syntax: C#*

     public MySqlConnection();

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlConnection Constructor Overload List:
connector-net-ref-mysqlclient-mysqlconnectionconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnectionconstructor2,  Prev: connector-net-ref-mysqlclient-mysqlconnectionconstructor1,  Up: connector-net-ref-mysqlclient-mysqlconnectionconstructor

30.2.4.13 `MySqlConnection' Constructor
.......................................

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal connectionString As String _
     )

*Syntax: C#*

     public MySqlConnection(
     stringconnectionString
     );

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlConnection Constructor Overload List:
connector-net-ref-mysqlclient-mysqlconnectionconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-connectionstring,  Next: connector-net-ref-mysqlclient-mysqlconnection-connectiontimeout,  Prev: connector-net-ref-mysqlclient-mysqlconnectionconstructor,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

30.2.4.14 ConnectionString Property
...................................

*Syntax: Visual Basic*

     NotOverridable Public Property ConnectionString As String _
     _
       Implements IDbConnection.ConnectionString

*Syntax: C#*

     public string ConnectionString {get; set;}

*Implements*

IDbConnection.ConnectionString

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-connectiontimeout,  Next: connector-net-ref-mysqlclient-mysqlconnection-database,  Prev: connector-net-ref-mysqlclient-mysqlconnection-connectionstring,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

30.2.4.15 ConnectionTimeout Property
....................................

*Syntax: Visual Basic*

     NotOverridable Public ReadOnly Property ConnectionTimeout As Integer _
     _
       Implements IDbConnection.ConnectionTimeout

*Syntax: C#*

     public int ConnectionTimeout {get;}

*Implements*

IDbConnection.ConnectionTimeout

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-database,  Next: connector-net-ref-mysqlclient-mysqlconnection-datasource,  Prev: connector-net-ref-mysqlclient-mysqlconnection-connectiontimeout,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

30.2.4.16 Database Property
...........................

*Syntax: Visual Basic*

     NotOverridable Public ReadOnly Property Database As String _
     _
       Implements IDbConnection.Database

*Syntax: C#*

     public string Database {get;}

*Implements*

IDbConnection.Database

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-datasource,  Next: connector-net-ref-mysqlclient-mysqlconnection-serverthread,  Prev: connector-net-ref-mysqlclient-mysqlconnection-database,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

30.2.4.17 DataSource Property
.............................

Gets the name of the MySQL server to which to connect.

*Syntax: Visual Basic*

     Public ReadOnly Property DataSource As String

*Syntax: C#*

     public string DataSource {get;}

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-serverthread,  Next: connector-net-ref-mysqlclient-mysqlconnection-serverversion,  Prev: connector-net-ref-mysqlclient-mysqlconnection-datasource,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

30.2.4.18 ServerThread Property
...............................

Returns the id of the server thread this connection is executing on

*Syntax: Visual Basic*

     Public ReadOnly Property ServerThread As Integer

*Syntax: C#*

     public int ServerThread {get;}

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-serverversion,  Next: connector-net-ref-mysqlclient-mysqlconnection-state,  Prev: connector-net-ref-mysqlclient-mysqlconnection-serverthread,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

30.2.4.19 ServerVersion Property
................................

*Syntax: Visual Basic*

     Public ReadOnly Property ServerVersion As String

*Syntax: C#*

     public string ServerVersion {get;}

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-state,  Next: connector-net-ref-mysqlclient-mysqlconnection-usecompression,  Prev: connector-net-ref-mysqlclient-mysqlconnection-serverversion,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

30.2.4.20 State Property
........................

*Syntax: Visual Basic*

     NotOverridable Public ReadOnly Property State As ConnectionState _
     _
       Implements IDbConnection.State

*Syntax: C#*

     public System.Data.ConnectionState State {get;}

*Implements*

IDbConnection.State

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-usecompression,  Next: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overloads,  Prev: connector-net-ref-mysqlclient-mysqlconnection-state,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

30.2.4.21 UseCompression Property
.................................

Indicates if this connection should use compression when communicating
with the server.

*Syntax: Visual Basic*

     Public ReadOnly Property UseCompression As Boolean

*Syntax: C#*

     public bool UseCompression {get;}

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overloads,  Next: connector-net-ref-mysqlclient-mysqlconnection-changedatabase,  Prev: connector-net-ref-mysqlclient-mysqlconnection-usecompression,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

30.2.4.22 BeginTransaction Method
.................................

* Menu:

* connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-1::  `MySqlConnection.BeginTransaction' Method
* connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-2::  `MySqlConnection.BeginTransaction' Method

*Overload List*

   * *Note public MySqlTransaction BeginTransaction();:
     connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-1.

   * *Note public MySqlTransaction BeginTransaction(IsolationLevel);:
     connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-2.

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-1,  Next: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overloads,  Up: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overloads

30.2.4.23 `MySqlConnection.BeginTransaction' Method
...................................................

* Menu:

* connector-net-ref-mysqlclient-mysqltransaction::  `MySqlTransaction' Class

*Syntax: Visual Basic*

     Overloads Public Function BeginTransaction() As MySqlTransaction

*Syntax: C#*

     public MySqlTransaction BeginTransaction();

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlConnection.BeginTransaction Overload List:
connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqltransaction,  Prev: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-1,  Up: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-1

30.2.4.24 `MySqlTransaction' Class
..................................

* Menu:

* connector-net-ref-mysqlclient-mysqltransactionmembers::  `MySqlTransaction' Members

For a list of all members of this type, see *Note MySqlTransaction
Members: connector-net-ref-mysqlclient-mysqltransactionmembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlTransaction_
       Implements IDbTransaction, IDisposable

*Syntax: C#*

     public sealed class MySqlTransaction : IDbTransaction, IDisposable

*Thread Safety*

Public static (Sharedin Visual Basic) members of this type are safe for
multithreaded operations. Instance members are notguaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlTransaction Members:
connector-net-ref-mysqlclient-mysqltransactionmembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqltransactionmembers,  Prev: connector-net-ref-mysqlclient-mysqltransaction,  Up: connector-net-ref-mysqlclient-mysqltransaction

30.2.4.25 `MySqlTransaction' Members
....................................

* Menu:

* connector-net-ref-mysqlclient-mysqltransaction-connection::  Connection Property
* connector-net-ref-mysqlclient-mysqltransaction-isolationlevel::  IsolationLevel Property
* connector-net-ref-mysqlclient-mysqltransaction-commit::  `MySqlTransaction.Commit' Method
* connector-net-ref-mysqlclient-mysqltransaction-rollback::  `MySqlTransaction.Rollback' Method

*Note MySqlTransaction overview:
connector-net-ref-mysqlclient-mysqltransaction.

*Public Instance Properties*

*Note Connection:                    Gets the *Note MySqlConnection:
connector-net-ref-mysqlclient-mysqltransaction-connection.connector-net-ref-mysqlclient-mysqlconnection.
                                     object associated with the
                                     transaction, or a null reference
                                     (Nothing in Visual Basic) if the
                                     transaction is no longer valid.
*Note IsolationLevel:                Specifies the IsolationLevelfor
connector-net-ref-mysqlclient-mysqltransaction-isolationlevel.this transaction.

*Public Instance Methods*

*Note Commit:                        
connector-net-ref-mysqlclient-mysqltransaction-commit.
Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
*Note Rollback:                      
connector-net-ref-mysqlclient-mysqltransaction-rollback.
ToString(inherited from Object)      Returns a Stringthat represents the
                                     current Object.

*See Also*

*Note MySqlTransaction Class:
connector-net-ref-mysqlclient-mysqltransaction , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqltransaction-connection,  Next: connector-net-ref-mysqlclient-mysqltransaction-isolationlevel,  Prev: connector-net-ref-mysqlclient-mysqltransactionmembers,  Up: connector-net-ref-mysqlclient-mysqltransactionmembers

30.2.4.26 Connection Property
.............................

Gets the *Note MySqlConnection:
connector-net-ref-mysqlclient-mysqlconnection.  object associated with
the transaction, or a null reference (Nothing in Visual Basic) if the
transaction is no longer valid.

*Syntax: Visual Basic*

     Public ReadOnly Property Connection As MySqlConnection

*Syntax: C#*

     public MySqlConnection Connection {get;}

*Property Value*

The *Note MySqlConnection:
connector-net-ref-mysqlclient-mysqlconnection.  object associated with
this transaction.

*Remarks*

A single application may have multiple database connections, each with
zero or more transactions. This property enables you to determine the
connection object associated with a particular transaction created by
*Note BeginTransaction:
connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-1
.

*See Also*

*Note MySqlTransaction Class:
connector-net-ref-mysqlclient-mysqltransaction , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqltransaction-isolationlevel,  Next: connector-net-ref-mysqlclient-mysqltransaction-commit,  Prev: connector-net-ref-mysqlclient-mysqltransaction-connection,  Up: connector-net-ref-mysqlclient-mysqltransactionmembers

30.2.4.27 IsolationLevel Property
.................................

Specifies the IsolationLevelfor this transaction.

*Syntax: Visual Basic*

     NotOverridable Public ReadOnly Property IsolationLevel As IsolationLevel _
     _
       Implements IDbTransaction.IsolationLevel

*Syntax: C#*

     public System.Data.IsolationLevel IsolationLevel {get;}

*Property Value*

The IsolationLevel for this transaction.  The default is ReadCommitted.

*Implements*

IDbTransaction.IsolationLevel

*Remarks*

Parallel transactions are not supported.  Therefore, the IsolationLevel
applies to the entire transaction.

*See Also*

*Note MySqlTransaction Class:
connector-net-ref-mysqlclient-mysqltransaction , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqltransaction-commit,  Next: connector-net-ref-mysqlclient-mysqltransaction-rollback,  Prev: connector-net-ref-mysqlclient-mysqltransaction-isolationlevel,  Up: connector-net-ref-mysqlclient-mysqltransactionmembers

30.2.4.28 `MySqlTransaction.Commit' Method
..........................................

*Syntax: Visual Basic*

     NotOverridable Public Sub Commit() _
     _
       Implements IDbTransaction.Commit

*Syntax: C#*

     public void Commit();

*Implements*

IDbTransaction.Commit

*See Also*

*Note MySqlTransaction Class:
connector-net-ref-mysqlclient-mysqltransaction , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqltransaction-rollback,  Prev: connector-net-ref-mysqlclient-mysqltransaction-commit,  Up: connector-net-ref-mysqlclient-mysqltransactionmembers

30.2.4.29 `MySqlTransaction.Rollback' Method
............................................

*Syntax: Visual Basic*

     NotOverridable Public Sub Rollback() _
     _
       Implements IDbTransaction.Rollback

*Syntax: C#*

     public void Rollback();

*Implements*

IDbTransaction.Rollback

*See Also*

*Note MySqlTransaction Class:
connector-net-ref-mysqlclient-mysqltransaction , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-1,  Up: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overloads

30.2.4.30 `MySqlConnection.BeginTransaction' Method
...................................................

*Syntax: Visual Basic*

     Overloads Public Function BeginTransaction( _
        ByVal iso As IsolationLevel _
     ) As MySqlTransaction

*Syntax: C#*

     public MySqlTransaction BeginTransaction(
     IsolationLeveliso
     );

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlConnection.BeginTransaction Overload List:
connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-changedatabase,  Next: connector-net-ref-mysqlclient-mysqlconnection-close,  Prev: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overloads,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

30.2.4.31 `MySqlConnection.ChangeDatabase' Method
.................................................

*Syntax: Visual Basic*

     NotOverridable Public Sub ChangeDatabase( _
        ByVal databaseName As String _
     ) _
     _
       Implements IDbConnection.ChangeDatabase

*Syntax: C#*

     public void ChangeDatabase(
     stringdatabaseName
     );

*Implements*

IDbConnection.ChangeDatabase

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-close,  Next: connector-net-ref-mysqlclient-mysqlconnection-createcommand,  Prev: connector-net-ref-mysqlclient-mysqlconnection-changedatabase,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

30.2.4.32 `MySqlConnection.Close' Method
........................................

*Syntax: Visual Basic*

     NotOverridable Public Sub Close() _
     _
       Implements IDbConnection.Close

*Syntax: C#*

     public void Close();

*Implements*

IDbConnection.Close

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-createcommand,  Next: connector-net-ref-mysqlclient-mysqlconnection-open,  Prev: connector-net-ref-mysqlclient-mysqlconnection-close,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

30.2.4.33 `MySqlConnection.CreateCommand' Method
................................................

*Syntax: Visual Basic*

     Public Function CreateCommand() As MySqlCommand

*Syntax: C#*

     public MySqlCommand CreateCommand();

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-open,  Next: connector-net-ref-mysqlclient-mysqlconnection-ping,  Prev: connector-net-ref-mysqlclient-mysqlconnection-createcommand,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

30.2.4.34 `MySqlConnection.Open' Method
.......................................

*Syntax: Visual Basic*

     NotOverridable Public Sub Open() _
     _
       Implements IDbConnection.Open

*Syntax: C#*

     public void Open();

*Implements*

IDbConnection.Open

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-ping,  Next: connector-net-ref-mysqlclient-mysqlconnection-infomessage,  Prev: connector-net-ref-mysqlclient-mysqlconnection-open,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

30.2.4.35 `MySqlConnection.Ping' Method
.......................................

Ping

*Syntax: Visual Basic*

     Public Function Ping() As Boolean

*Syntax: C#*

     public bool Ping();

*Return Value*

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-infomessage,  Next: connector-net-ref-mysqlclient-mysqlconnection-statechange,  Prev: connector-net-ref-mysqlclient-mysqlconnection-ping,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

30.2.4.36 `MySqlConnection.InfoMessage' Event
.............................................

* Menu:

* connector-net-ref-mysqlclient-mysqlinfomessageeventhandler::  `MySqlInfoMessageEventHandler' Delegate

*Syntax: Visual Basic*

     Public Event InfoMessage As MySqlInfoMessageEventHandler

*Syntax: C#*

     public event MySqlInfoMessageEventHandler InfoMessage;

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlinfomessageeventhandler,  Prev: connector-net-ref-mysqlclient-mysqlconnection-infomessage,  Up: connector-net-ref-mysqlclient-mysqlconnection-infomessage

30.2.4.37 `MySqlInfoMessageEventHandler' Delegate
.................................................

* Menu:

* connector-net-ref-mysqlclient-mysqlinfomessageeventargs::  `MySqlInfoMessageEventArgs' Class

Represents the method that will handle the *Note InfoMessage:
connector-net-ref-mysqlclient-mysqlconnection-infomessage.  event of a
*Note MySqlConnection: connector-net-ref-mysqlclient-mysqlconnection .

*Syntax: Visual Basic*

     Public Delegate Sub MySqlInfoMessageEventHandler( _
        ByVal sender As Object, _
        ByVal args As MySqlInfoMessageEventArgs _
     )

*Syntax: C#*

     public delegate void MySqlInfoMessageEventHandler(
     objectsender,
     MySqlInfoMessageEventArgsargs
     );

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlinfomessageeventargs,  Prev: connector-net-ref-mysqlclient-mysqlinfomessageeventhandler,  Up: connector-net-ref-mysqlclient-mysqlinfomessageeventhandler

30.2.4.38 `MySqlInfoMessageEventArgs' Class
...........................................

* Menu:

* connector-net-ref-mysqlclient-mysqlinfomessageeventargsmembers::  `MySqlInfoMessageEventArgs' Members

Provides data for the InfoMessage event. This class cannot be inherited.

For a list of all members of this type, see *Note
MySqlInfoMessageEventArgs Members:
connector-net-ref-mysqlclient-mysqlinfomessageeventargsmembers .

*Syntax: Visual Basic*

     Public Class MySqlInfoMessageEventArgs_
       Inherits EventArgs

*Syntax: C#*

     public class MySqlInfoMessageEventArgs : EventArgs

*Thread Safety*

Public static (Sharedin Visual Basic) members of this type are safe for
multithreaded operations. Instance members are notguaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlInfoMessageEventArgs Members:
connector-net-ref-mysqlclient-mysqlinfomessageeventargsmembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlinfomessageeventargsmembers,  Prev: connector-net-ref-mysqlclient-mysqlinfomessageeventargs,  Up: connector-net-ref-mysqlclient-mysqlinfomessageeventargs

30.2.4.39 `MySqlInfoMessageEventArgs' Members
.............................................

* Menu:

* connector-net-ref-mysqlclient-mysqlinfomessageeventargsconstructor::  `MySqlInfoMessageEventArgs' Constructor
* connector-net-ref-mysqlclient-mysqlinfomessageeventargs-errors::  `MySqlInfoMessageEventArgs.errors' Field

*Note MySqlInfoMessageEventArgs overview:
connector-net-ref-mysqlclient-mysqlinfomessageeventargs.

*Public Instance Constructors*

*Note MySqlInfoMessageEventArgs      Initializes a new instance of the
Constructor:                         *Note MySqlInfoMessageEventArgs:
connector-net-ref-mysqlclient-mysqlinfomessageeventargsconstructor.connector-net-ref-mysqlclient-mysqlinfomessageeventargs.
                                     class.

*Public Instance Fields*

*Note errors:                        
connector-net-ref-mysqlclient-mysqlinfomessageeventargs-errors.

*Public Instance Methods*

Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
ToString(inherited from Object)      Returns a Stringthat represents the
                                     current Object.

*Protected Instance Methods*

Finalize(inherited from Object)      Allows an Objectto attempt to free
                                     resources and perform other cleanup
                                     operations before the Objectis
                                     reclaimed by garbage collection.
MemberwiseClone(inherited from       Creates a shallow copy of the
Object)                              current Object.

*See Also*

*Note MySqlInfoMessageEventArgs Class:
connector-net-ref-mysqlclient-mysqlinfomessageeventargs , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlinfomessageeventargsconstructor,  Next: connector-net-ref-mysqlclient-mysqlinfomessageeventargs-errors,  Prev: connector-net-ref-mysqlclient-mysqlinfomessageeventargsmembers,  Up: connector-net-ref-mysqlclient-mysqlinfomessageeventargsmembers

30.2.4.40 `MySqlInfoMessageEventArgs' Constructor
.................................................

Initializes a new instance of the *Note MySqlInfoMessageEventArgs:
connector-net-ref-mysqlclient-mysqlinfomessageeventargs.  class.

*Syntax: Visual Basic*

     Public Sub New()

*Syntax: C#*

     public MySqlInfoMessageEventArgs();

*See Also*

*Note MySqlInfoMessageEventArgs Class:
connector-net-ref-mysqlclient-mysqlinfomessageeventargs , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlinfomessageeventargs-errors,  Prev: connector-net-ref-mysqlclient-mysqlinfomessageeventargsconstructor,  Up: connector-net-ref-mysqlclient-mysqlinfomessageeventargsmembers

30.2.4.41 `MySqlInfoMessageEventArgs.errors' Field
..................................................

* Menu:

* connector-net-ref-mysqlclient-mysqlerror::  `MySqlError' Class

*Syntax: Visual Basic*

     Public errors As MySqlError()

*Syntax: C#*

     public MySqlError[] errors;

*See Also*

*Note MySqlInfoMessageEventArgs Class:
connector-net-ref-mysqlclient-mysqlinfomessageeventargs , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlerror,  Prev: connector-net-ref-mysqlclient-mysqlinfomessageeventargs-errors,  Up: connector-net-ref-mysqlclient-mysqlinfomessageeventargs-errors

30.2.4.42 `MySqlError' Class
............................

* Menu:

* connector-net-ref-mysqlclient-mysqlerrormembers::  `MySqlError' Members

Collection of error codes that can be returned by the server

For a list of all members of this type, see *Note MySqlError Members:
connector-net-ref-mysqlclient-mysqlerrormembers .

*Syntax: Visual Basic*

     Public Class MySqlError

*Syntax: C#*

     public class MySqlError

*Thread Safety*

Public static (Shared in Visual Basic) members of this type are safe for
multithreaded operations. Instance members are not guaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlError Members:
connector-net-ref-mysqlclient-mysqlerrormembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlerrormembers,  Prev: connector-net-ref-mysqlclient-mysqlerror,  Up: connector-net-ref-mysqlclient-mysqlerror

30.2.4.43 `MySqlError' Members
..............................

* Menu:

* connector-net-ref-mysqlclient-mysqlerrorconstructor::  `MySqlError' Constructor
* connector-net-ref-mysqlclient-mysqlerror-code::  Code Property
* connector-net-ref-mysqlclient-mysqlerror-level::  Level Property
* connector-net-ref-mysqlclient-mysqlerror-message::  Message Property

*Note MySqlError overview: connector-net-ref-mysqlclient-mysqlerror.

*Public Instance Constructors*

*Note MySqlError Constructor:        
connector-net-ref-mysqlclient-mysqlerrorconstructor.

*Public Instance Properties*

*Note Code:                          Error code
connector-net-ref-mysqlclient-mysqlerror-code.
*Note Level:                         Error level
connector-net-ref-mysqlclient-mysqlerror-level.
*Note Message:                       Error message
connector-net-ref-mysqlclient-mysqlerror-message.

*Public Instance Methods*

Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
ToString(inherited from Object)      Returns a Stringthat represents the
                                     current Object.

*Protected Instance Methods*

Finalize(inherited from Object)      Allows an Objectto attempt to free
                                     resources and perform other cleanup
                                     operations before the Objectis
                                     reclaimed by garbage collection.
MemberwiseClone(inherited from       Creates a shallow copy of the
Object)                              current Object.

*See Also*

*Note MySqlError Class: connector-net-ref-mysqlclient-mysqlerror ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlerrorconstructor,  Next: connector-net-ref-mysqlclient-mysqlerror-code,  Prev: connector-net-ref-mysqlclient-mysqlerrormembers,  Up: connector-net-ref-mysqlclient-mysqlerrormembers

30.2.4.44 `MySqlError' Constructor
..................................

*Syntax: Visual Basic*

     Public Sub New( _
        ByVal level As String, _
        ByVal code As Integer, _
        ByVal message As String _
     )

*Syntax: C#*

     public MySqlError(
     stringlevel,
     intcode,
     stringmessage
     );

*Parameters*

   * `level':

   * `code':

   * `message':

*See Also*

*Note MySqlError Class: connector-net-ref-mysqlclient-mysqlerror ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlerror-code,  Next: connector-net-ref-mysqlclient-mysqlerror-level,  Prev: connector-net-ref-mysqlclient-mysqlerrorconstructor,  Up: connector-net-ref-mysqlclient-mysqlerrormembers

30.2.4.45 Code Property
.......................

Error code

*Syntax: Visual Basic*

     Public ReadOnly Property Code As Integer

*Syntax: C#*

     public int Code {get;}

*See Also*

*Note MySqlError Class: connector-net-ref-mysqlclient-mysqlerror ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlerror-level,  Next: connector-net-ref-mysqlclient-mysqlerror-message,  Prev: connector-net-ref-mysqlclient-mysqlerror-code,  Up: connector-net-ref-mysqlclient-mysqlerrormembers

30.2.4.46 Level Property
........................

Error level

*Syntax: Visual Basic*

     Public ReadOnly Property Level As String

*Syntax: C#*

     public string Level {get;}

*See Also*

*Note MySqlError Class: connector-net-ref-mysqlclient-mysqlerror ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlerror-message,  Prev: connector-net-ref-mysqlclient-mysqlerror-level,  Up: connector-net-ref-mysqlclient-mysqlerrormembers

30.2.4.47 Message Property
..........................

Error message

*Syntax: Visual Basic*

     Public ReadOnly Property Message As String

*Syntax: C#*

     public string Message {get;}

*See Also*

*Note MySqlError Class: connector-net-ref-mysqlclient-mysqlerror ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlconnection-statechange,  Prev: connector-net-ref-mysqlclient-mysqlconnection-infomessage,  Up: connector-net-ref-mysqlclient-mysqlconnectionmembers

30.2.4.48 `MySqlConnection.StateChange' Event
.............................................

*Syntax: Visual Basic*

     Public Event StateChange As StateChangeEventHandler

*Syntax: C#*

     public event StateChangeEventHandler StateChange;

*See Also*

*Note MySqlConnection Class:
connector-net-ref-mysqlclient-mysqlconnection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandconstructor4,  Prev: connector-net-ref-mysqlclient-mysqlcommandconstructor3,  Up: connector-net-ref-mysqlclient-mysqlcommandconstructor

30.2.4.49 `MySqlCommand' Constructor
....................................

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal cmdText As String, _
        ByVal connection As MySqlConnection, _
        ByVal transaction As MySqlTransaction _
     )

*Syntax: C#*

     public MySqlCommand(
     stringcmdText,
     MySqlConnectionconnection,
     MySqlTransactiontransaction
     );

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlCommand Constructor Overload List:
connector-net-ref-mysqlclient-mysqlcommandconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-commandtext,  Next: connector-net-ref-mysqlclient-mysqlcommand-commandtimeout,  Prev: connector-net-ref-mysqlclient-mysqlcommandconstructor,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

30.2.4.50 CommandText Property
..............................

*Syntax: Visual Basic*

     NotOverridable Public Property CommandText As String _
     _
       Implements IDbCommand.CommandText

*Syntax: C#*

     public string CommandText {get; set;}

*Implements*

IDbCommand.CommandText

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-commandtimeout,  Next: connector-net-ref-mysqlclient-mysqlcommand-commandtype,  Prev: connector-net-ref-mysqlclient-mysqlcommand-commandtext,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

30.2.4.51 CommandTimeout Property
.................................

*Syntax: Visual Basic*

     NotOverridable Public Property CommandTimeout As Integer _
     _
       Implements IDbCommand.CommandTimeout

*Syntax: C#*

     public int CommandTimeout {get; set;}

*Implements*

IDbCommand.CommandTimeout

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-commandtype,  Next: connector-net-ref-mysqlclient-mysqlcommand-connection,  Prev: connector-net-ref-mysqlclient-mysqlcommand-commandtimeout,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

30.2.4.52 CommandType Property
..............................

*Syntax: Visual Basic*

     NotOverridable Public Property CommandType As CommandType _
     _
       Implements IDbCommand.CommandType

*Syntax: C#*

     public System.Data.CommandType CommandType {get; set;}

*Implements*

IDbCommand.CommandType

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-connection,  Next: connector-net-ref-mysqlclient-mysqlcommand-isprepared,  Prev: connector-net-ref-mysqlclient-mysqlcommand-commandtype,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

30.2.4.53 Connection Property
.............................

*Syntax: Visual Basic*

     Public Property Connection As MySqlConnection

*Syntax: C#*

     public MySqlConnection Connection {get; set;}

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-isprepared,  Next: connector-net-ref-mysqlclient-mysqlcommand-parameters,  Prev: connector-net-ref-mysqlclient-mysqlcommand-connection,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

30.2.4.54 IsPrepared Property
.............................

*Syntax: Visual Basic*

     Public ReadOnly Property IsPrepared As Boolean

*Syntax: C#*

     public bool IsPrepared {get;}

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-parameters,  Next: connector-net-ref-mysqlclient-mysqlcommand-transaction,  Prev: connector-net-ref-mysqlclient-mysqlcommand-isprepared,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

30.2.4.55 Parameters Property
.............................

* Menu:

* connector-net-ref-mysqlclient-mysqlparametercollection::  `MySqlParameterCollection' Class

*Syntax: Visual Basic*

     Public ReadOnly Property Parameters As MySqlParameterCollection

*Syntax: C#*

     public MySqlParameterCollection Parameters {get;}

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection,  Prev: connector-net-ref-mysqlclient-mysqlcommand-parameters,  Up: connector-net-ref-mysqlclient-mysqlcommand-parameters

30.2.4.56 `MySqlParameterCollection' Class
..........................................

* Menu:

* connector-net-ref-mysqlclient-mysqlparametercollectionmembers::  `MySqlParameterCollection' Members

Represents a collection of parameters relevant to a *Note MySqlCommand:
connector-net-ref-mysqlclient-mysqlcommand.  as well as their
respective mappings to columns in a DataSet. This class cannot be
inherited.

For a list of all members of this type, see *Note
MySqlParameterCollection Members:
connector-net-ref-mysqlclient-mysqlparametercollectionmembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlParameterCollection_
       Inherits MarshalByRefObject_
       Implements IDataParameterCollection, IList, ICollection, IEnumerable

*Syntax: C#*

     public sealed class MySqlParameterCollection : MarshalByRefObject, IDataParameterCollection, IList, ICollection, IEnumerable

*Thread Safety*

Public static (Shared in Visual Basic) members of this type are safe
for multithreaded operations. Instance members are not guaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlParameterCollection Members:
connector-net-ref-mysqlclient-mysqlparametercollectionmembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollectionmembers,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection,  Up: connector-net-ref-mysqlclient-mysqlparametercollection

30.2.4.57 `MySqlParameterCollection' Members
............................................

* Menu:

* connector-net-ref-mysqlclient-mysqlparametercollectionconstructor::  `MySqlParameterCollection' Constructor
* connector-net-ref-mysqlclient-mysqlparametercollection-count::  Count Property
* connector-net-ref-mysqlclient-mysqlparametercollectionitem::  Item Property
* connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads::  Add Method
* connector-net-ref-mysqlclient-mysqlparametercollection-clear::  `MySqlParameterCollection.Clear' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-contains-overloads::  Contains Method
* connector-net-ref-mysqlclient-mysqlparametercollection-copyto::  `MySqlParameterCollection.CopyTo' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overloads::  IndexOf Method
* connector-net-ref-mysqlclient-mysqlparametercollection-insert::  `MySqlParameterCollection.Insert' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-remove::  `MySqlParameterCollection.Remove' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overloads::  RemoveAt Method

*Note MySqlParameterCollection overview:
connector-net-ref-mysqlclient-mysqlparametercollection.

*Public Instance Constructors*

*Note MySqlParameterCollection       Initializes a new instance of the
Constructor:                         *Note MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollectionconstructor.connector-net-ref-mysqlclient-mysqlparametercollection.
                                     class.

*Public Instance Properties*

*Note Count:                         Gets the number of MySqlParameter
connector-net-ref-mysqlclient-mysqlparametercollection-count.objects in the collection.
*Note Item:                          Overloaded. Gets the *Note
connector-net-ref-mysqlclient-mysqlparametercollectionitem.MySqlParameter:
                                     connector-net-ref-mysqlclient-mysqlparameter.
                                     with a specified attribute. In C#,
                                     this property is the indexer for the
                                     *Note MySqlParameterCollection:
                                     connector-net-ref-mysqlclient-mysqlparametercollection.
                                     class.

*Public Instance Methods*

*Note Add:                           Overloaded. Adds the specified
connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads.*Note MySqlParameter:
                                     connector-net-ref-mysqlclient-mysqlparameter.
                                     object to the *Note
                                     MySqlParameterCollection:
                                     connector-net-ref-mysqlclient-mysqlparametercollection
                                     .
*Note Clear:                         Removes all items from the
connector-net-ref-mysqlclient-mysqlparametercollection-clear.collection.
*Note Contains:                      Overloaded. Gets a value indicating
connector-net-ref-mysqlclient-mysqlparametercollection-contains-overloads.whether a *Note MySqlParameter:
                                     connector-net-ref-mysqlclient-mysqlparameter.
                                     exists in the collection.
*Note CopyTo:                        Copies MySqlParameter objects from
connector-net-ref-mysqlclient-mysqlparametercollection-copyto.the MySqlParameterCollection to the
                                     specified array.
CreateObjRef(inherited from          Creates an object that contains all
MarshalByRefObject)                  the relevant information required to
                                     generate a proxy used to
                                     communicate with a remote object.
Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetLifetimeService(inherited from    Retrieves the current lifetime
MarshalByRefObject)                  service object that controls the
                                     lifetime policy for this instance.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
*Note IndexOf:                       Overloaded. Gets the location of a
connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overloads.*Note MySqlParameter:
                                     connector-net-ref-mysqlclient-mysqlparameter.
                                     in the collection.
InitializeLifetimeService(inherited  Obtains a lifetime service object
from MarshalByRefObject)             to control the lifetime policy for
                                     this instance.
*Note Insert:                        Inserts a MySqlParameter into the
connector-net-ref-mysqlclient-mysqlparametercollection-insert.collection at the specified index.
*Note Remove:                        Removes the specified
connector-net-ref-mysqlclient-mysqlparametercollection-remove.MySqlParameter from the collection.
*Note RemoveAt:                      Overloaded. Removes the specified
connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overloads.*Note MySqlParameter:
                                     connector-net-ref-mysqlclient-mysqlparameter.
                                     from the collection.
ToString(inherited from Object)      Returns a Stringthat represents the
                                     current Object.

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollectionconstructor,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-count,  Prev: connector-net-ref-mysqlclient-mysqlparametercollectionmembers,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionmembers

30.2.4.58 `MySqlParameterCollection' Constructor
................................................

Initializes a new instance of the *Note MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection.  class.

*Syntax: Visual Basic*

     Public Sub New()

*Syntax: C#*

     public MySqlParameterCollection();

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-count,  Next: connector-net-ref-mysqlclient-mysqlparametercollectionitem,  Prev: connector-net-ref-mysqlclient-mysqlparametercollectionconstructor,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionmembers

30.2.4.59 Count Property
........................

Gets the number of MySqlParameter objects in the collection.

*Syntax: Visual Basic*

     NotOverridable Public ReadOnly Property Count As Integer _
     _
       Implements ICollection.Count

*Syntax: C#*

     public int Count {get;}

*Implements*

ICollection.Count

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollectionitem,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-count,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionmembers

30.2.4.60 Item Property
.......................

* Menu:

* connector-net-ref-mysqlclient-mysqlparameter::  `MySqlParameter' Class
* connector-net-ref-mysqlclient-mysqlparametercollection-item1::  Item Property (Int32)
* connector-net-ref-mysqlclient-mysqlparametercollection-item2::  Item Property (String)

Gets the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  with a specified
attribute. In C#, this property is the indexer for the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection.  class.

*Overload List*

Gets the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  at the specified index.

   * *Note public MySqlParameter this[int] {get; set;}:
     connector-net-ref-mysqlclient-mysqlparametercollection-item1.

Gets the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  with the specified name.

   * *Note public MySqlParameter this[string] {get; set;}:
     connector-net-ref-mysqlclient-mysqlparametercollection-item2.

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-item1,  Prev: connector-net-ref-mysqlclient-mysqlparametercollectionitem,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionitem

30.2.4.61 `MySqlParameter' Class
................................

* Menu:

* connector-net-ref-mysqlclient-mysqlparametermembers::  `MySqlParameter' Members

Represents a parameter to a *Note MySqlCommand:
connector-net-ref-mysqlclient-mysqlcommand , and optionally, its
mapping to DataSetcolumns.  This class cannot be inherited.

For a list of all members of this type, see *Note MySqlParameter
Members: connector-net-ref-mysqlclient-mysqlparametermembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlParameter_
       Inherits MarshalByRefObject_
       Implements IDataParameter, IDbDataParameter, ICloneable

*Syntax: C#*

     public sealed class MySqlParameter : MarshalByRefObject, IDataParameter, IDbDataParameter, ICloneable

*Thread Safety*

Public static (Shared in Visual Basic) members of this type are safe
for multithreaded operations.  Instance members are not guaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlParameter Members:
connector-net-ref-mysqlclient-mysqlparametermembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametermembers,  Prev: connector-net-ref-mysqlclient-mysqlparameter,  Up: connector-net-ref-mysqlclient-mysqlparameter

30.2.4.62 `MySqlParameter' Members
..................................

* Menu:

* connector-net-ref-mysqlclient-mysqlparameterconstructor::  `MySqlParameter' Constructor
* connector-net-ref-mysqlclient-mysqlparameter-dbtype::  DbType Property
* connector-net-ref-mysqlclient-mysqlparameter-direction::  Direction Property
* connector-net-ref-mysqlclient-mysqlparameter-isnullable::  IsNullable Property
* connector-net-ref-mysqlclient-mysqlparameter-isunsigned::  IsUnsigned Property
* connector-net-ref-mysqlclient-mysqlparameter-mysqldbtype::  `MySqlDbType' Property
* connector-net-ref-mysqlclient-mysqlparameter-parametername::  ParameterName Property
* connector-net-ref-mysqlclient-mysqlparameter-precision::  Precision Property
* connector-net-ref-mysqlclient-mysqlparameter-scale::  Scale Property
* connector-net-ref-mysqlclient-mysqlparameter-size::  Size Property
* connector-net-ref-mysqlclient-mysqlparameter-sourcecolumn::  SourceColumn Property
* connector-net-ref-mysqlclient-mysqlparameter-sourceversion::  SourceVersion Property
* connector-net-ref-mysqlclient-mysqlparameter-tostring::  `MySqlParameter.ToString' Method

*Note MySqlParameter overview:
connector-net-ref-mysqlclient-mysqlparameter.

*Public Instance Constructors*

*Note MySqlParameter:                Overloaded. Initializes a new
connector-net-ref-mysqlclient-mysqlparameterconstructor.instance of the MySqlParameter
                                     class.

*Public Instance Properties*

*Note DbType:                        Gets or sets the DbTypeof the
connector-net-ref-mysqlclient-mysqlparameter-dbtype.parameter.
*Note Direction:                     Gets or sets a value indicating
connector-net-ref-mysqlclient-mysqlparameter-direction.whether the parameter is input-only,
                                     output-only, bidirectional, or a
                                     stored procedure return value
                                     parameter. As of MySQL version 4.1
                                     and earlier, input-only is the only
                                     valid choice.
*Note IsNullable:                    Gets or sets a value indicating
connector-net-ref-mysqlclient-mysqlparameter-isnullable.whether the parameter accepts null
                                     values.
*Note IsUnsigned:                    
connector-net-ref-mysqlclient-mysqlparameter-isunsigned.
*Note MySqlDbType:                   Gets or sets the MySqlDbType of the
connector-net-ref-mysqlclient-mysqlparameter-mysqldbtype.parameter.
*Note ParameterName:                 Gets or sets the name of the
connector-net-ref-mysqlclient-mysqlparameter-parametername.MySqlParameter.
*Note Precision:                     Gets or sets the maximum number of
connector-net-ref-mysqlclient-mysqlparameter-precision.digits used to represent the *Note
                                     Value:
                                     connector-net-ref-mysqlclient-mysqlparameter-value.
                                     property.
*Note Scale:                         Gets or sets the number of decimal
connector-net-ref-mysqlclient-mysqlparameter-scale.places to which *Note Value:
                                     connector-net-ref-mysqlclient-mysqlparameter-value.
                                     is resolved.
*Note Size:                          Gets or sets the maximum size, in
connector-net-ref-mysqlclient-mysqlparameter-size.bytes, of the data within the
                                     column.
*Note SourceColumn:                  Gets or sets the name of the source
connector-net-ref-mysqlclient-mysqlparameter-sourcecolumn.column that is mapped to the
                                     DataSetand used for loading or
                                     returning the *Note Value:
                                     connector-net-ref-mysqlclient-mysqlparameter-value
                                     .
*Note SourceVersion:                 Gets or sets the DataRowVersionto
connector-net-ref-mysqlclient-mysqlparameter-sourceversion.use when loading *Note Value:
                                     connector-net-ref-mysqlclient-mysqlparameter-value
                                     .
*Note Value:                         Gets or sets the value of the
connector-net-ref-mysqlclient-mysqlparameter-value.parameter.

*Public Instance Methods*

CreateObjRef(inherited from          Creates an object that contains all
MarshalByRefObject)                  the relevant information required to
                                     generate a proxy used to communicate
                                     with a remote object.
Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetLifetimeService(inherited from    Retrieves the current lifetime
MarshalByRefObject)                  service object that controls the
                                     lifetime policy for this instance.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
InitializeLifetimeService(inherited  Obtains a lifetime service object
from MarshalByRefObject)             to control the lifetime policy for
                                     this instance.
*Note ToString:                      Overridden. Gets a string
connector-net-ref-mysqlclient-mysqlparameter-tostring.containing the *Note ParameterName:
                                     connector-net-ref-mysqlclient-mysqlparameter-parametername
                                     .

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameterconstructor,  Next: connector-net-ref-mysqlclient-mysqlparameter-dbtype,  Prev: connector-net-ref-mysqlclient-mysqlparametermembers,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

30.2.4.63 `MySqlParameter' Constructor
......................................

* Menu:

* connector-net-ref-mysqlclient-mysqlparameterconstructor1::  `MySqlParameter' Constructor ()
* connector-net-ref-mysqlclient-mysqlparameterconstructor3::  `MySqlParameter' Constructor
* connector-net-ref-mysqlclient-mysqlparameterconstructor4::  `MySqlParameter' Constructor (String, MySqlDbType, Int32)
* connector-net-ref-mysqlclient-mysqlparameterconstructor6::  `MySqlParameter' Constructor
* connector-net-ref-mysqlclient-mysqlparameterconstructor5::  `MySqlParameter' Constructor
* connector-net-ref-mysqlclient-mysqlparameterconstructor2::  `MySqlParameter' Constructor

Initializes a new instance of the MySqlParameter class.

*Overload List*

Initializes a new instance of the MySqlParameter class.

   * *Note public MySqlParameter();:
     connector-net-ref-mysqlclient-mysqlparameterconstructor1.

Initializes a new instance of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  class with the parameter
name and the data type.

   * *Note public MySqlParameter(string:
     (MySqlDbType);)connector-net-ref-mysqlclient-mysqlparameterconstructor3.

Initializes a new instance of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  class with the parameter
name, the *Note MySqlDbType: connector-net-ref-mysqlclient-mysqldbtype
, and the size.

   * *Note public MySqlParameter(string:
     (MySqlDbType)connector-net-ref-mysqlclient-mysqlparameterconstructor4.

Initializes a new instance of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  class with the parameter
name, the type of the parameter, the size of the parameter, a
ParameterDirection, the precision of the parameter, the scale of the
parameter, the source column, a DataRowVersionto use, and the value of
the parameter.

   * *Note public MySqlParameter(string:
     (MySqlDbType)connector-net-ref-mysqlclient-mysqlparameterconstructor6.ParameterDirection,bool,byte,byte,string,DataRowVersion,object);

Initializes a new instance of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  class with the parameter
name, the *Note MySqlDbType: connector-net-ref-mysqlclient-mysqldbtype
, the size, and the source column name.

   * *Note public MySqlParameter(string:
     (MySqlDbType)connector-net-ref-mysqlclient-mysqlparameterconstructor5.string);

Initializes a new instance of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  class with the parameter
name and a value of the new MySqlParameter.

   * *Note public MySqlParameter(string:
     (object);)connector-net-ref-mysqlclient-mysqlparameterconstructor2.

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameterconstructor1,  Next: connector-net-ref-mysqlclient-mysqlparameterconstructor3,  Prev: connector-net-ref-mysqlclient-mysqlparameterconstructor,  Up: connector-net-ref-mysqlclient-mysqlparameterconstructor

30.2.4.64 `MySqlParameter' Constructor ()
.........................................

Initializes a new instance of the MySqlParameter class.

*Syntax: Visual Basic*

     Overloads Public Sub New()

*Syntax: C#*

     public MySqlParameter();

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameter Constructor Overload List:
connector-net-ref-mysqlclient-mysqlparameterconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameterconstructor3,  Next: connector-net-ref-mysqlclient-mysqlparameterconstructor4,  Prev: connector-net-ref-mysqlclient-mysqlparameterconstructor1,  Up: connector-net-ref-mysqlclient-mysqlparameterconstructor

30.2.4.65 `MySqlParameter' Constructor
......................................

* Menu:

* connector-net-ref-mysqlclient-mysqldbtype::  `MySqlDbType' Enumeration

Initializes a new instance of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  class with the parameter
name and the data type.

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal parameterName As String, _
        ByVal dbType As MySqlDbType _
     )

*Syntax: C#*

     public MySqlParameter(
     stringparameterName,
     MySqlDbTypedbType
     );

*Parameters*

   * `parameterName': The name of the parameter to map.

   * `dbType': One of the *Note MySqlDbType:
     connector-net-ref-mysqlclient-mysqldbtype.  values.

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameter Constructor Overload List:
connector-net-ref-mysqlclient-mysqlparameterconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldbtype,  Prev: connector-net-ref-mysqlclient-mysqlparameterconstructor3,  Up: connector-net-ref-mysqlclient-mysqlparameterconstructor3

30.2.4.66 `MySqlDbType' Enumeration
...................................

Specifies MySQL specific data type of a field, property, for use in a
*Note MySqlParameter: connector-net-ref-mysqlclient-mysqlparameter .

*Syntax: Visual Basic*

     Public Enum MySqlDbType

*Syntax: C#*

     public enum MySqlDbType

*Members*

*Member Name*                        *Description*
Newdate                              Obsolete. Use Datetime or Date type.
Timestamp                            A timestamp. The range is
                                     '1970-01-01 00:00:01' to sometime
                                     in the year 2038.
Time                                 The range is '-838:59:59' to
                                     '838:59:59'
Date                                 Date The supported range is
                                     '1000-01-01' to '9999-12-31'
Datetime                             The supported range is '1000-01-01
                                     00:00:00' to '9999-12-31 23:59:59'
Year                                 A year in 2- or 4-digit format
                                     (default is 4-digit). The allowable
                                     values are 1901 to 2155, 0000 in
                                     the 4-digit year format, and
                                     1970-2069 if you use the 2-digit
                                     format (70-69).
TinyBlob                             A BLOB column with a maximum length
                                     of 255 (2^8 - 1) characters
Blob                                 A BLOB column with a maximum length
                                     of 65535 (2^16 - 1) characters
MediumBlob                           A BLOB column with a maximum length
                                     of 16777215 (2^24 - 1) characters
LongBlob                             A BLOB column with a maximum length
                                     of 4294967295 or 4G (2^32 - 1)
                                     characters
Int16                                A 16-bit signed integer. The signed
                                     range is -32768 to 32767.  The
                                     unsigned range is 0 to 65535
Int24                                Specifies a 24 (3 byte) signed or
                                     unsigned value
Int32                                A 32-bit signed integer
Int64                                A 64-bit signed integer
Byte                                 The signed range is -128 to 127.
                                     The unsigned range is 0 to 255.
Float                                A small (single-precision)
                                     floating-point number. Allowable
                                     values are -3.402823466E+38 to
                                     -1.175494351E-38, 0, and
                                     1.175494351E-38 to 3.402823466E+38.
Double                               A normal-size (double-precision)
                                     floating-point number. Allowable
                                     values are -1.7976931348623157E+308
                                     to -2.2250738585072014E-308, 0, and
                                     2.2250738585072014E-308 to
                                     1.7976931348623157E+308.
UByte                                An 8-bit unsigned value
UInt16                               A 16-bit unsigned value
UInt24                               A 24-bit unsigned value
UInt32                               A 32-bit unsigned value
UInt64                               A 64-bit unsigned value
Decimal                              A fixed precision and scale numeric
                                     value between -1038 -1 and 10 38 -1
NewDecimal                           New Decimal
Set                                  A set. A string object that can
                                     have zero or more values, each of
                                     which must be chosen from the list
                                     of values 'value1', 'value2', ... A
                                     SET can have a maximum of 64
                                     members.
String                               Obsolete Use VarChar type
VarChar                              A variable-length string containing
                                     0 to 255 characters
VarString                            A variable-length string containing
                                     0 to 65535 characters
Enum                                 An enumeration. A string object
                                     that can have only one value, chosen
                                     from the list of values 'value1',
                                     'value2', ..., NULL or the special
                                     "" error value. An ENUM can have a
                                     maximum of 65535 distinct values.
Geometry                             
Bit                                  Bit-field data type
TinyText                             A nonbinary string column
                                     supporting a maximum length of 255
                                     (2^8 - 1) characters
Text                                 A nonbinary string column
                                     supporting a maximum length of
                                     65535 (2^16 - 1) characters
MediumText                           A nonbinary string column
                                     supporting a maximum length of
                                     16777215 (2^24 - 1) characters
LongText                             A nonbinary string column
                                     supporting a maximum length of
                                     4294967295 (2^32 - 1) characters

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameterconstructor4,  Next: connector-net-ref-mysqlclient-mysqlparameterconstructor6,  Prev: connector-net-ref-mysqlclient-mysqlparameterconstructor3,  Up: connector-net-ref-mysqlclient-mysqlparameterconstructor

30.2.4.67 `MySqlParameter' Constructor (String, MySqlDbType, Int32)
...................................................................

Initializes a new instance of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  class with the parameter
name, the *Note MySqlDbType: connector-net-ref-mysqlclient-mysqldbtype
, and the size.

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal parameterName As String, _
        ByVal dbType As MySqlDbType, _
        ByVal size As Integer _
     )

*Syntax: C#*

     public MySqlParameter(
     stringparameterName,
     MySqlDbTypedbType,
     intsize
     );

*Parameters*

   * `parameterName': The name of the parameter to map.

   * `dbType': One of the *Note MySqlDbType:
     connector-net-ref-mysqlclient-mysqldbtype.  values.

   * `size': The length of the parameter.

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameter Constructor Overload List:
connector-net-ref-mysqlclient-mysqlparameterconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameterconstructor6,  Next: connector-net-ref-mysqlclient-mysqlparameterconstructor5,  Prev: connector-net-ref-mysqlclient-mysqlparameterconstructor4,  Up: connector-net-ref-mysqlclient-mysqlparameterconstructor

30.2.4.68 `MySqlParameter' Constructor
......................................

* Menu:

* connector-net-ref-mysqlclient-mysqlparameter-value::  Value Property

Initializes a new instance of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  class with the parameter
name, the type of the parameter, the size of the parameter, a
ParameterDirection, the precision of the parameter, the scale of the
parameter, the source column, a DataRowVersionto use, and the value of
the parameter.

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal parameterName As String, _
        ByVal dbType As MySqlDbType, _
        ByVal size As Integer, _
        ByVal direction As ParameterDirection, _
        ByVal isNullable As Boolean, _
        ByVal precision As Byte, _
        ByVal scale As Byte, _
        ByVal sourceColumn As String, _
        ByVal sourceVersion As DataRowVersion, _
        ByVal value As Object _
     )

*Syntax: C#*

     public MySqlParameter(
     stringparameterName,
     MySqlDbTypedbType,
     intsize,
     ParameterDirectiondirection,
     boolisNullable,
     byteprecision,
     bytescale,
     stringsourceColumn,
     DataRowVersionsourceVersion,
     objectvalue
     );

*Parameters*

   * `parameterName': The name of the parameter to map.

   * `dbType': One of the *Note MySqlDbType:
     connector-net-ref-mysqlclient-mysqldbtype.  values.

   * `size': The length of the parameter.

   * `direction': One of the ParameterDirectionvalues.

   * `isNullable': true if the value of the field can be null,
     otherwise false.

   * `precision': The total number of digits to the left and right of
     the decimal point to which *Note Value:
     connector-net-ref-mysqlclient-mysqlparameter-value.  is resolved.

   * `scale': The total number of decimal places to which *Note Value:
     connector-net-ref-mysqlclient-mysqlparameter-value.  is resolved.

   * `sourceColumn': The name of the source column.

   * `sourceVersion': One of the DataRowVersionvalues.

   * `value': An Objectthat is the value of the *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter .

*Exceptions*

*Exception Type*                     *Condition*
ArgumentException                    

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameter Constructor Overload List:
connector-net-ref-mysqlclient-mysqlparameterconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-value,  Prev: connector-net-ref-mysqlclient-mysqlparameterconstructor6,  Up: connector-net-ref-mysqlclient-mysqlparameterconstructor6

30.2.4.69 Value Property
........................

Gets or sets the value of the parameter.

*Syntax: Visual Basic*

     NotOverridable Public Property Value As Object _
     _
       Implements IDataParameter.Value

*Syntax: C#*

     public object Value {get; set;}

*Implements*

IDataParameter.Value

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameterconstructor5,  Next: connector-net-ref-mysqlclient-mysqlparameterconstructor2,  Prev: connector-net-ref-mysqlclient-mysqlparameterconstructor6,  Up: connector-net-ref-mysqlclient-mysqlparameterconstructor

30.2.4.70 `MySqlParameter' Constructor
......................................

Initializes a new instance of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  class with the parameter
name, the *Note MySqlDbType: connector-net-ref-mysqlclient-mysqldbtype
, the size, and the source column name.

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal parameterName As String, _
        ByVal dbType As MySqlDbType, _
        ByVal size As Integer, _
        ByVal sourceColumn As String _
     )

*Syntax: C#*

     public MySqlParameter(
     stringparameterName,
     MySqlDbTypedbType,
     intsize,
     stringsourceColumn
     );

*Parameters*

   * `parameterName': The name of the parameter to map.

   * `dbType': One of the *Note MySqlDbType:
     connector-net-ref-mysqlclient-mysqldbtype.  values.

   * `size': The length of the parameter.

   * `sourceColumn': The name of the source column.

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameter Constructor Overload List:
connector-net-ref-mysqlclient-mysqlparameterconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameterconstructor2,  Prev: connector-net-ref-mysqlclient-mysqlparameterconstructor5,  Up: connector-net-ref-mysqlclient-mysqlparameterconstructor

30.2.4.71 `MySqlParameter' Constructor
......................................

Initializes a new instance of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  class with the parameter
name and a value of the new MySqlParameter.

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal parameterName As String, _
        ByVal value As Object _
     )

*Syntax: C#*

     public MySqlParameter(
     stringparameterName,
     objectvalue
     );

*Parameters*

   * `parameterName': The name of the parameter to map.

   * `value': An Objectthat is the value of the *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter .

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameter Constructor Overload List:
connector-net-ref-mysqlclient-mysqlparameterconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-dbtype,  Next: connector-net-ref-mysqlclient-mysqlparameter-direction,  Prev: connector-net-ref-mysqlclient-mysqlparameterconstructor,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

30.2.4.72 DbType Property
.........................

Gets or sets the DbTypeof the parameter.

*Syntax: Visual Basic*

     NotOverridable Public Property DbType As DbType _
     _
       Implements IDataParameter.DbType

*Syntax: C#*

     public System.Data.DbType DbType {get; set;}

*Implements*

IDataParameter.DbType

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-direction,  Next: connector-net-ref-mysqlclient-mysqlparameter-isnullable,  Prev: connector-net-ref-mysqlclient-mysqlparameter-dbtype,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

30.2.4.73 Direction Property
............................

Gets or sets a value indicating whether the parameter is input-only,
output-only, bidirectional, or a stored procedure return value
parameter. As of MySQL version 4.1 and earlier, input-only is the only
valid choice.

*Syntax: Visual Basic*

     NotOverridable Public Property Direction As ParameterDirection _
     _
       Implements IDataParameter.Direction

*Syntax: C#*

     public System.Data.ParameterDirection Direction {get; set;}

*Implements*

IDataParameter.Direction

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-isnullable,  Next: connector-net-ref-mysqlclient-mysqlparameter-isunsigned,  Prev: connector-net-ref-mysqlclient-mysqlparameter-direction,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

30.2.4.74 IsNullable Property
.............................

Gets or sets a value indicating whether the parameter accepts null
values.

*Syntax: Visual Basic*

     NotOverridable Public Property IsNullable As Boolean _
     _
       Implements IDataParameter.IsNullable

*Syntax: C#*

     public bool IsNullable {get; set;}

*Implements*

IDataParameter.IsNullable

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-isunsigned,  Next: connector-net-ref-mysqlclient-mysqlparameter-mysqldbtype,  Prev: connector-net-ref-mysqlclient-mysqlparameter-isnullable,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

30.2.4.75 IsUnsigned Property
.............................

*Syntax: Visual Basic*

     Public Property IsUnsigned As Boolean

*Syntax: C#*

     public bool IsUnsigned {get; set;}

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-mysqldbtype,  Next: connector-net-ref-mysqlclient-mysqlparameter-parametername,  Prev: connector-net-ref-mysqlclient-mysqlparameter-isunsigned,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

30.2.4.76 `MySqlDbType' Property
................................

Gets or sets the MySqlDbType of the parameter.

*Syntax: Visual Basic*

     Public Property MySqlDbType As MySqlDbType

*Syntax: C#*

     public MySqlDbType MySqlDbType {get; set;}

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-parametername,  Next: connector-net-ref-mysqlclient-mysqlparameter-precision,  Prev: connector-net-ref-mysqlclient-mysqlparameter-mysqldbtype,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

30.2.4.77 ParameterName Property
................................

Gets or sets the name of the MySqlParameter.

*Syntax: Visual Basic*

     NotOverridable Public Property ParameterName As String _
     _
       Implements IDataParameter.ParameterName

*Syntax: C#*

     public string ParameterName {get; set;}

*Implements*

IDataParameter.ParameterName

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-precision,  Next: connector-net-ref-mysqlclient-mysqlparameter-scale,  Prev: connector-net-ref-mysqlclient-mysqlparameter-parametername,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

30.2.4.78 Precision Property
............................

Gets or sets the maximum number of digits used to represent the *Note
Value: connector-net-ref-mysqlclient-mysqlparameter-value.  property.

*Syntax: Visual Basic*

     NotOverridable Public Property Precision As Byte _
     _
       Implements IDbDataParameter.Precision

*Syntax: C#*

     public byte Precision {get; set;}

*Implements*

IDbDataParameter.Precision

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-scale,  Next: connector-net-ref-mysqlclient-mysqlparameter-size,  Prev: connector-net-ref-mysqlclient-mysqlparameter-precision,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

30.2.4.79 Scale Property
........................

Gets or sets the number of decimal places to which *Note Value:
connector-net-ref-mysqlclient-mysqlparameter-value.  is resolved.

*Syntax: Visual Basic*

     NotOverridable Public Property Scale As Byte _
     _
       Implements IDbDataParameter.Scale

*Syntax: C#*

     public byte Scale {get; set;}

*Implements*

IDbDataParameter.Scale

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-size,  Next: connector-net-ref-mysqlclient-mysqlparameter-sourcecolumn,  Prev: connector-net-ref-mysqlclient-mysqlparameter-scale,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

30.2.4.80 Size Property
.......................

Gets or sets the maximum size, in bytes, of the data within the column.

*Syntax: Visual Basic*

     NotOverridable Public Property Size As Integer _
     _
       Implements IDbDataParameter.Size

*Syntax: C#*

     public int Size {get; set;}

*Implements*

IDbDataParameter.Size

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-sourcecolumn,  Next: connector-net-ref-mysqlclient-mysqlparameter-sourceversion,  Prev: connector-net-ref-mysqlclient-mysqlparameter-size,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

30.2.4.81 SourceColumn Property
...............................

Gets or sets the name of the source column that is mapped to the
DataSetand used for loading or returning the *Note Value:
connector-net-ref-mysqlclient-mysqlparameter-value .

*Syntax: Visual Basic*

     NotOverridable Public Property SourceColumn As String _
     _
       Implements IDataParameter.SourceColumn

*Syntax: C#*

     public string SourceColumn {get; set;}

*Implements*

IDataParameter.SourceColumn

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-sourceversion,  Next: connector-net-ref-mysqlclient-mysqlparameter-tostring,  Prev: connector-net-ref-mysqlclient-mysqlparameter-sourcecolumn,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

30.2.4.82 SourceVersion Property
................................

Gets or sets the DataRowVersionto use when loading *Note Value:
connector-net-ref-mysqlclient-mysqlparameter-value .

*Syntax: Visual Basic*

     NotOverridable Public Property SourceVersion As DataRowVersion _
     _
       Implements IDataParameter.SourceVersion

*Syntax: C#*

     public System.Data.DataRowVersion SourceVersion {get; set;}

*Implements*

IDataParameter.SourceVersion

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparameter-tostring,  Prev: connector-net-ref-mysqlclient-mysqlparameter-sourceversion,  Up: connector-net-ref-mysqlclient-mysqlparametermembers

30.2.4.83 `MySqlParameter.ToString' Method
..........................................

Overridden. Gets a string containing the *Note ParameterName:
connector-net-ref-mysqlclient-mysqlparameter-parametername .

*Syntax: Visual Basic*

     Overrides Public Function ToString() As String

*Syntax: C#*

     public override string ToString();

*Return Value*

*See Also*

*Note MySqlParameter Class:
connector-net-ref-mysqlclient-mysqlparameter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-item1,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-item2,  Prev: connector-net-ref-mysqlclient-mysqlparameter,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionitem

30.2.4.84 Item Property (Int32)
...............................

Gets the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  at the specified index.

*Syntax: Visual Basic*

     Overloads Public Default Property Item( _
        ByVal index As Integer _
     ) As MySqlParameter

*Syntax: C#*

     public MySqlParameter this[
     intindex
     ] {get; set;}

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.Item Overload List:
connector-net-ref-mysqlclient-mysqlparametercollectionitem.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-item2,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-item1,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionitem

30.2.4.85 Item Property (String)
................................

Gets the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  with the specified name.

*Syntax: Visual Basic*

     Overloads Public Default Property Item( _
        ByVal name As String _
     ) As MySqlParameter

*Syntax: C#*

     public MySqlParameter this[
     stringname
     ] {get; set;}

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.Item Overload List:
connector-net-ref-mysqlclient-mysqlparametercollectionitem.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-clear,  Prev: connector-net-ref-mysqlclient-mysqlparametercollectionitem,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionmembers

30.2.4.86 Add Method
....................

* Menu:

* connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-2::  `MySqlParameterCollection.Add' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-1::  `MySqlParameterCollection.Add' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-4::  `MySqlParameterCollection.Add' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-5::  `MySqlParameterCollection.Add' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-6::  `MySqlParameterCollection.Add' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-3::  `MySqlParameterCollection.Add' Method

Adds the specified *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection .

*Overload List*

Adds the specified *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection .

   * *Note public MySqlParameter Add(MySqlParameter);:
     connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-2.

Adds the specified *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection .

   * *Note public int Add(object);:
     connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-1.

Adds a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection.  given the
parameter name and the data type.

   * *Note public MySqlParameter Add(string:
     (MySqlDbType);)connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-4.

Adds a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection.  with the
parameter name, the data type, and the column length.

   * *Note public MySqlParameter Add(string:
     (MySqlDbType)connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-5.

Adds a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection.  with the
parameter name, the data type, the column length, and the source column
name.

   * *Note public MySqlParameter Add(string:
     (MySqlDbType)connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-6.string);

Adds a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection.  given the
specified parameter name and value.

   * *Note public MySqlParameter Add(string:
     (object);)connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-3.

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-2,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-1,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads

30.2.4.87 `MySqlParameterCollection.Add' Method
...............................................

Adds the specified *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection .

*Syntax: Visual Basic*

     Overloads Public Function Add( _
        ByVal value As MySqlParameter _
     ) As MySqlParameter

*Syntax: C#*

     public MySqlParameter Add(
     MySqlParametervalue
     );

*Parameters*

   * `value': The *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter.  to add to the
     collection.

*Return Value*

The newly added *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object.

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.Add Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-1,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-4,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-2,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads

30.2.4.88 `MySqlParameterCollection.Add' Method
...............................................

Adds the specified *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection .

*Syntax: Visual Basic*

     NotOverridable Overloads Public Function Add( _
        ByVal value As Object _
     ) As Integer _
     _
       Implements IList.Add

*Syntax: C#*

     public int Add(
     objectvalue
     );

*Parameters*

   * `value': The *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter.  to add to the
     collection.

*Return Value*

The index of the new *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object.

*Implements*

IList.Add

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.Add Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-4,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-5,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-1,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads

30.2.4.89 `MySqlParameterCollection.Add' Method
...............................................

Adds a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection.  given the
parameter name and the data type.

*Syntax: Visual Basic*

     Overloads Public Function Add( _
        ByVal parameterName As String, _
        ByVal dbType As MySqlDbType _
     ) As MySqlParameter

*Syntax: C#*

     public MySqlParameter Add(
     stringparameterName,
     MySqlDbTypedbType
     );

*Parameters*

   * `parameterName': The name of the parameter.

   * `dbType': One of the *Note MySqlDbType:
     connector-net-ref-mysqlclient-mysqldbtype.  values.

*Return Value*

The newly added *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object.

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.Add Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-5,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-6,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-4,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads

30.2.4.90 `MySqlParameterCollection.Add' Method
...............................................

Adds a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection.  with the
parameter name, the data type, and the column length.

*Syntax: Visual Basic*

     Overloads Public Function Add( _
        ByVal parameterName As String, _
        ByVal dbType As MySqlDbType, _
        ByVal size As Integer _
     ) As MySqlParameter

*Syntax: C#*

     public MySqlParameter Add(
     stringparameterName,
     MySqlDbTypedbType,
     intsize
     );

*Parameters*

   * `parameterName': The name of the parameter.

   * `dbType': One of the *Note MySqlDbType:
     connector-net-ref-mysqlclient-mysqldbtype.  values.

   * `size': The length of the column.

*Return Value*

The newly added *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object.

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.Add Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-6,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-3,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-5,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads

30.2.4.91 `MySqlParameterCollection.Add' Method
...............................................

Adds a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection.  with the
parameter name, the data type, the column length, and the source column
name.

*Syntax: Visual Basic*

     Overloads Public Function Add( _
        ByVal parameterName As String, _
        ByVal dbType As MySqlDbType, _
        ByVal size As Integer, _
        ByVal sourceColumn As String _
     ) As MySqlParameter

*Syntax: C#*

     public MySqlParameter Add(
     stringparameterName,
     MySqlDbTypedbType,
     intsize,
     stringsourceColumn
     );

*Parameters*

   * `parameterName': The name of the parameter.

   * `dbType': One of the *Note MySqlDbType:
     connector-net-ref-mysqlclient-mysqldbtype.  values.

   * `size': The length of the column.

   * `sourceColumn': The name of the source column.

*Return Value*

The newly added *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object.

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.Add Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-3,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-6,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads

30.2.4.92 `MySqlParameterCollection.Add' Method
...............................................

Adds a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  to the *Note
MySqlParameterCollection:
connector-net-ref-mysqlclient-mysqlparametercollection.  given the
specified parameter name and value.

*Syntax: Visual Basic*

     Overloads Public Function Add( _
        ByVal parameterName As String, _
        ByVal value As Object _
     ) As MySqlParameter

*Syntax: C#*

     public MySqlParameter Add(
     stringparameterName,
     objectvalue
     );

*Parameters*

   * `parameterName': The name of the parameter.

   * `value': The *Note Value:
     connector-net-ref-mysqlclient-mysqlparameter-value.  of the *Note
     MySqlParameter: connector-net-ref-mysqlclient-mysqlparameter.  to
     add to the collection.

*Return Value*

The newly added *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object.

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.Add Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-clear,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-contains-overloads,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionmembers

30.2.4.93 `MySqlParameterCollection.Clear' Method
.................................................

Removes all items from the collection.

*Syntax: Visual Basic*

     NotOverridable Public Sub Clear() _
     _
       Implements IList.Clear

*Syntax: C#*

     public void Clear();

*Implements*

IList.Clear

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-contains-overloads,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-copyto,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-clear,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionmembers

30.2.4.94 Contains Method
.........................

* Menu:

* connector-net-ref-mysqlclient-mysqlparametercollection-contains-overload-1::  `MySqlParameterCollection.Contains' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-contains-overload-2::  `MySqlParameterCollection.Contains' Method

Gets a value indicating whether a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  exists in the collection.

*Overload List*

Gets a value indicating whether a MySqlParameter exists in the
collection.

   * *Note public bool Contains(object);:
     connector-net-ref-mysqlclient-mysqlparametercollection-contains-overload-1.

Gets a value indicating whether a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  with the specified
parameter name exists in the collection.

   * *Note public bool Contains(string);:
     connector-net-ref-mysqlclient-mysqlparametercollection-contains-overload-2.

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-contains-overload-1,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-contains-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-contains-overloads,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-contains-overloads

30.2.4.95 `MySqlParameterCollection.Contains' Method
....................................................

Gets a value indicating whether a MySqlParameter exists in the
collection.

*Syntax: Visual Basic*

     NotOverridable Overloads Public Function Contains( _
        ByVal value As Object _
     ) As Boolean _
     _
       Implements IList.Contains

*Syntax: C#*

     public bool Contains(
     objectvalue
     );

*Parameters*

   * `value': The value of the *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter.  object to find.

*Return Value*

true if the collection contains the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object; otherwise, false.

*Implements*

IList.Contains

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.Contains Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-contains-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-contains-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-contains-overload-1,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-contains-overloads

30.2.4.96 `MySqlParameterCollection.Contains' Method
....................................................

Gets a value indicating whether a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  with the specified
parameter name exists in the collection.

*Syntax: Visual Basic*

     NotOverridable Overloads Public Function Contains( _
        ByVal name As String _
     ) As Boolean _
     _
       Implements IDataParameterCollection.Contains

*Syntax: C#*

     public bool Contains(
     stringname
     );

*Parameters*

   * `name': The name of the *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter.  object to find.

*Return Value*

true if the collection contains the parameter; otherwise, false.

*Implements*

IDataParameterCollection.Contains

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.Contains Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-contains-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-copyto,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overloads,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-contains-overloads,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionmembers

30.2.4.97 `MySqlParameterCollection.CopyTo' Method
..................................................

Copies MySqlParameter objects from the MySqlParameterCollection to the
specified array.

*Syntax: Visual Basic*

     NotOverridable Public Sub CopyTo( _
        ByVal array As Array, _
        ByVal index As Integer _
     ) _
     _
       Implements ICollection.CopyTo

*Syntax: C#*

     public void CopyTo(
     Arrayarray,
     intindex
     );

*Parameters*

   * `array':

   * `index':

*Implements*

ICollection.CopyTo

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overloads,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-insert,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-copyto,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionmembers

30.2.4.98 IndexOf Method
........................

* Menu:

* connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overload-1::  `MySqlParameterCollection.IndexOf' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overload-2::  `MySqlParameterCollection.IndexOf' Method

Gets the location of a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  in the collection.

*Overload List*

Gets the location of a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  in the collection.

   * *Note public int IndexOf(object);:
     connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overload-1.

Gets the location of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  in the collection with a
specific parameter name.

   * *Note public int IndexOf(string);:
     connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overload-2.

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overload-1,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overloads,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overloads

30.2.4.99 `MySqlParameterCollection.IndexOf' Method
...................................................

Gets the location of a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  in the collection.

*Syntax: Visual Basic*

     NotOverridable Overloads Public Function IndexOf( _
        ByVal value As Object _
     ) As Integer _
     _
       Implements IList.IndexOf

*Syntax: C#*

     public int IndexOf(
     objectvalue
     );

*Parameters*

   * `value': The *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter.  object to locate.

*Return Value*

The zero-based location of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  in the collection.

*Implements*

IList.IndexOf

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.IndexOf Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overload-1,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overloads

30.2.4.100 `MySqlParameterCollection.IndexOf' Method
....................................................

Gets the location of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  in the collection with a
specific parameter name.

*Syntax: Visual Basic*

     NotOverridable Overloads Public Function IndexOf( _
        ByVal parameterName As String _
     ) As Integer _
     _
       Implements IDataParameterCollection.IndexOf

*Syntax: C#*

     public int IndexOf(
     stringparameterName
     );

*Parameters*

   * `parameterName': The name of the *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter.  object to retrieve.

*Return Value*

The zero-based location of the *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  in the collection.

*Implements*

IDataParameterCollection.IndexOf

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.IndexOf Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-insert,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-remove,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overloads,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionmembers

30.2.4.101 `MySqlParameterCollection.Insert' Method
...................................................

Inserts a MySqlParameter into the collection at the specified index.

*Syntax: Visual Basic*

     NotOverridable Public Sub Insert( _
        ByVal index As Integer, _
        ByVal value As Object _
     ) _
     _
       Implements IList.Insert

*Syntax: C#*

     public void Insert(
     intindex,
     objectvalue
     );

*Parameters*

   * `index':

   * `value':

*Implements*

IList.Insert

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-remove,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overloads,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-insert,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionmembers

30.2.4.102 `MySqlParameterCollection.Remove' Method
...................................................

Removes the specified MySqlParameter from the collection.

*Syntax: Visual Basic*

     NotOverridable Public Sub Remove( _
        ByVal value As Object _
     ) _
     _
       Implements IList.Remove

*Syntax: C#*

     public void Remove(
     objectvalue
     );

*Parameters*

   * `value':

*Implements*

IList.Remove

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overloads,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-remove,  Up: connector-net-ref-mysqlclient-mysqlparametercollectionmembers

30.2.4.103 RemoveAt Method
..........................

* Menu:

* connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overload-1::  `MySqlParameterCollection.RemoveAt' Method
* connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overload-2::  `MySqlParameterCollection.RemoveAt' Method

Removes the specified *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  from the collection.

*Overload List*

Removes the specified *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  from the collection
using a specific index.

   * *Note public void RemoveAt(int);:
     connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overload-1.

Removes the specified *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  from the collection
using the parameter name.

   * *Note public void RemoveAt(string);:
     connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overload-2.

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overload-1,  Next: connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overloads,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overloads

30.2.4.104 `MySqlParameterCollection.RemoveAt' Method
.....................................................

Removes the specified *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  from the collection
using a specific index.

*Syntax: Visual Basic*

     NotOverridable Overloads Public Sub RemoveAt( _
        ByVal index As Integer _
     ) _
     _
       Implements IList.RemoveAt

*Syntax: C#*

     public void RemoveAt(
     intindex
     );

*Parameters*

   * `index': The zero-based index of the parameter.

*Implements*

IList.RemoveAt

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.RemoveAt Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overload-1,  Up: connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overloads

30.2.4.105 `MySqlParameterCollection.RemoveAt' Method
.....................................................

Removes the specified *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  from the collection
using the parameter name.

*Syntax: Visual Basic*

     NotOverridable Overloads Public Sub RemoveAt( _
        ByVal name As String _
     ) _
     _
       Implements IDataParameterCollection.RemoveAt

*Syntax: C#*

     public void RemoveAt(
     stringname
     );

*Parameters*

   * `name': The name of the *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter.  object to retrieve.

*Implements*

IDataParameterCollection.RemoveAt

*See Also*

*Note MySqlParameterCollection Class:
connector-net-ref-mysqlclient-mysqlparametercollection , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlParameterCollection.RemoveAt Overload List:
connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-transaction,  Next: connector-net-ref-mysqlclient-mysqlcommand-updatedrowsource,  Prev: connector-net-ref-mysqlclient-mysqlcommand-parameters,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

30.2.4.106 Transaction Property
...............................

*Syntax: Visual Basic*

     Public Property Transaction As MySqlTransaction

*Syntax: C#*

     public MySqlTransaction Transaction {get; set;}

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-updatedrowsource,  Next: connector-net-ref-mysqlclient-mysqlcommand-cancel,  Prev: connector-net-ref-mysqlclient-mysqlcommand-transaction,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

30.2.4.107 UpdatedRowSource Property
....................................

*Syntax: Visual Basic*

     NotOverridable Public Property UpdatedRowSource As UpdateRowSource _
     _
       Implements IDbCommand.UpdatedRowSource

*Syntax: C#*

     public System.Data.UpdateRowSource UpdatedRowSource {get; set;}

*Implements*

IDbCommand.UpdatedRowSource

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-cancel,  Next: connector-net-ref-mysqlclient-mysqlcommand-createparameter,  Prev: connector-net-ref-mysqlclient-mysqlcommand-updatedrowsource,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

30.2.4.108 `MySqlCommand.Cancel' Method
.......................................

Attempts to cancel the execution of a MySqlCommand. This operation is
not supported.

*Syntax: Visual Basic*

     NotOverridable Public Sub Cancel() _
     _
       Implements IDbCommand.Cancel

*Syntax: C#*

     public void Cancel();

*Implements*

IDbCommand.Cancel

*Remarks*

Cancelling an executing command is currently not supported on any
version of MySQL.

*Exceptions*

*Exception Type*                     *Condition*
NotSupportedException                This operation is not supported.

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-createparameter,  Next: connector-net-ref-mysqlclient-mysqlcommand-executenonquery,  Prev: connector-net-ref-mysqlclient-mysqlcommand-cancel,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

30.2.4.109 `MySqlCommand.CreateParameter' Method
................................................

Creates a new instance of a *Note MySqlParameter:
connector-net-ref-mysqlclient-mysqlparameter.  object.

*Syntax: Visual Basic*

     Public Function CreateParameter() As MySqlParameter

*Syntax: C#*

     public MySqlParameter CreateParameter();

*Return Value*

A *Note MySqlParameter: connector-net-ref-mysqlclient-mysqlparameter.
object.

*Remarks*

This method is a strongly-typed version of CreateParameter.

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-executenonquery,  Next: connector-net-ref-mysqlclient-mysqlcommand-executereader-overloads,  Prev: connector-net-ref-mysqlclient-mysqlcommand-createparameter,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

30.2.4.110 `MySqlCommand.ExecuteNonQuery' Method
................................................

*Syntax: Visual Basic*

     NotOverridable Public Function ExecuteNonQuery() As Integer _
     _
       Implements IDbCommand.ExecuteNonQuery

*Syntax: C#*

     public int ExecuteNonQuery();

*Implements*

IDbCommand.ExecuteNonQuery

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-executereader-overloads,  Next: connector-net-ref-mysqlclient-mysqlcommand-executescalar,  Prev: connector-net-ref-mysqlclient-mysqlcommand-executenonquery,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

30.2.4.111 ExecuteReader Method
...............................

* Menu:

* connector-net-ref-mysqlclient-mysqlcommand-executereader-overload-1::  `MySqlCommand.ExecuteReader' Method
* connector-net-ref-mysqlclient-mysqlcommand-executereader-overload-2::  `MySqlCommand.ExecuteReader' Method

*Overload List*

   * *Note public MySqlDataReader ExecuteReader();:
     connector-net-ref-mysqlclient-mysqlcommand-executereader-overload-1.

   * *Note public MySqlDataReader ExecuteReader(CommandBehavior);:
     connector-net-ref-mysqlclient-mysqlcommand-executereader-overload-2.

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-executereader-overload-1,  Next: connector-net-ref-mysqlclient-mysqlcommand-executereader-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlcommand-executereader-overloads,  Up: connector-net-ref-mysqlclient-mysqlcommand-executereader-overloads

30.2.4.112 `MySqlCommand.ExecuteReader' Method
..............................................

* Menu:

* connector-net-ref-mysqlclient-mysqldatareader::  `MySqlDataReader' Class

*Syntax: Visual Basic*

     Overloads Public Function ExecuteReader() As MySqlDataReader

*Syntax: C#*

     public MySqlDataReader ExecuteReader();

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlCommand.ExecuteReader Overload List:
connector-net-ref-mysqlclient-mysqlcommand-executereader-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader,  Prev: connector-net-ref-mysqlclient-mysqlcommand-executereader-overload-1,  Up: connector-net-ref-mysqlclient-mysqlcommand-executereader-overload-1

30.2.4.113 `MySqlDataReader' Class
..................................

* Menu:

* connector-net-ref-mysqlclient-mysqldatareadermembers::  `MySqlDataReader' Members

Provides a means of reading a forward-only stream of rows from a MySQL
database. This class cannot be inherited.

For a list of all members of this type, see *Note MySqlDataReader
Members: connector-net-ref-mysqlclient-mysqldatareadermembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlDataReader_
       Inherits MarshalByRefObject_
       Implements IEnumerable, IDataReader, IDisposable, IDataRecord

*Syntax: C#*

     public sealed class MySqlDataReader : MarshalByRefObject, IEnumerable, IDataReader, IDisposable, IDataRecord

*Thread Safety*

Public static (Shared in Visual Basic) members of this type are safe
for multithreaded operations. Instance members are not guaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlDataReader Members:
connector-net-ref-mysqlclient-mysqldatareadermembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareadermembers,  Prev: connector-net-ref-mysqlclient-mysqldatareader,  Up: connector-net-ref-mysqlclient-mysqldatareader

30.2.4.114 `MySqlDataReader' Members
....................................

* Menu:

* connector-net-ref-mysqlclient-mysqldatareader-depth::  Depth Property
* connector-net-ref-mysqlclient-mysqldatareader-fieldcount::  FieldCount Property
* connector-net-ref-mysqlclient-mysqldatareader-hasrows::  HasRows Property
* connector-net-ref-mysqlclient-mysqldatareader-isclosed::  IsClosed Property
* connector-net-ref-mysqlclient-mysqldatareaderitem::  Item Property
* connector-net-ref-mysqlclient-mysqldatareader-recordsaffected::  RecordsAffected Property
* connector-net-ref-mysqlclient-mysqldatareader-close::  `MySqlDataReader.Close' Method
* connector-net-ref-mysqlclient-mysqldatareader-getboolean::  `MySqlDataReader.GetBoolean' Method
* connector-net-ref-mysqlclient-mysqldatareader-getbyte::  `MySqlDataReader.GetByte' Method
* connector-net-ref-mysqlclient-mysqldatareader-getbytes::  `MySqlDataReader.GetBytes' Method
* connector-net-ref-mysqlclient-mysqldatareader-getchar::  `MySqlDataReader.GetChar' Method
* connector-net-ref-mysqlclient-mysqldatareader-getchars::  `MySqlDataReader.GetChars' Method
* connector-net-ref-mysqlclient-mysqldatareader-getdatatypename::  `MySqlDataReader.GetDataTypeName' Method
* connector-net-ref-mysqlclient-mysqldatareader-getdatetime::  `MySqlDataReader.GetDateTime' Method
* connector-net-ref-mysqlclient-mysqldatareader-getdecimal::  `MySqlDataReader.GetDecimal' Method
* connector-net-ref-mysqlclient-mysqldatareader-getdouble::  `MySqlDataReader.GetDouble' Method
* connector-net-ref-mysqlclient-mysqldatareader-getfieldtype::  `MySqlDataReader.GetFieldType' Method
* connector-net-ref-mysqlclient-mysqldatareader-getfloat::  `MySqlDataReader.GetFloat' Method
* connector-net-ref-mysqlclient-mysqldatareader-getguid::  `MySqlDataReader.GetGuid' Method
* connector-net-ref-mysqlclient-mysqldatareader-getint16::  `MySqlDataReader.GetInt16' Method
* connector-net-ref-mysqlclient-mysqldatareader-getint32::  `MySqlDataReader.GetInt32' Method
* connector-net-ref-mysqlclient-mysqldatareader-getint64::  `MySqlDataReader.GetInt64' Method
* connector-net-ref-mysqlclient-mysqldatareader-getmysqldatetime::  `MySqlDataReader.GetMySqlDateTime' Method
* connector-net-ref-mysqlclient-mysqldatareader-getname::  `MySqlDataReader.GetName' Method
* connector-net-ref-mysqlclient-mysqldatareader-getordinal::  `MySqlDataReader.GetOrdinal' Method
* connector-net-ref-mysqlclient-mysqldatareader-getschematable::  `MySqlDataReader.GetSchemaTable' Method
* connector-net-ref-mysqlclient-mysqldatareader-getstring::  `MySqlDataReader.GetString' Method
* connector-net-ref-mysqlclient-mysqldatareader-gettimespan::  `MySqlDataReader.GetTimeSpan' Method
* connector-net-ref-mysqlclient-mysqldatareader-getuint16::  `MySqlDataReader.GetUInt16' Method
* connector-net-ref-mysqlclient-mysqldatareader-getuint32::  `MySqlDataReader.GetUInt32' Method
* connector-net-ref-mysqlclient-mysqldatareader-getuint64::  `MySqlDataReader.GetUInt64' Method
* connector-net-ref-mysqlclient-mysqldatareader-getvalue::  `MySqlDataReader.GetValue' Method
* connector-net-ref-mysqlclient-mysqldatareader-getvalues::  `MySqlDataReader.GetValues' Method
* connector-net-ref-mysqlclient-mysqldatareader-isdbnull::  `MySqlDataReader.IsDBNull' Method
* connector-net-ref-mysqlclient-mysqldatareader-nextresult::  `MySqlDataReader.NextResult' Method
* connector-net-ref-mysqlclient-mysqldatareader-read::  `MySqlDataReader.Read' Method

*Note MySqlDataReader overview:
connector-net-ref-mysqlclient-mysqldatareader.

*Public Instance Properties*

*Note Depth:                         Gets a value indicating the depth
connector-net-ref-mysqlclient-mysqldatareader-depth.of nesting for the current row. This
                                     method is not supported currently
                                     and always returns 0.
*Note FieldCount:                    Gets the number of columns in the
connector-net-ref-mysqlclient-mysqldatareader-fieldcount.current row.
*Note HasRows:                       Gets a value indicating whether the
connector-net-ref-mysqlclient-mysqldatareader-hasrows.MySqlDataReader contains one or more
                                     rows.
*Note IsClosed:                      Gets a value indicating whether the
connector-net-ref-mysqlclient-mysqldatareader-isclosed.data reader is closed.
*Note Item:                          Overloaded. Overloaded. Gets the
connector-net-ref-mysqlclient-mysqldatareaderitem.value of a column in its native
                                     format.  In C#, this property is
                                     the indexer for the MySqlDataReader
                                     class.
*Note RecordsAffected:               Gets the number of rows changed,
connector-net-ref-mysqlclient-mysqldatareader-recordsaffected.inserted, or deleted by execution of
                                     the SQL statement.

*Public Instance Methods*

*Note Close:                         Closes the MySqlDataReader object.
connector-net-ref-mysqlclient-mysqldatareader-close.
CreateObjRef(inherited from          Creates an object that contains all
MarshalByRefObject)                  the relevant information required to
                                     generate a proxy used to
                                     communicate with a remote object.
Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
*Note GetBoolean:                    Gets the value of the specified
connector-net-ref-mysqlclient-mysqldatareader-getboolean.column as a Boolean.
*Note GetByte:                       Gets the value of the specified
connector-net-ref-mysqlclient-mysqldatareader-getbyte.column as a byte.
*Note GetBytes:                      Reads a stream of bytes from the
connector-net-ref-mysqlclient-mysqldatareader-getbytes.specified column offset into the
                                     buffer an array starting at the
                                     given buffer offset.
*Note GetChar:                       Gets the value of the specified
connector-net-ref-mysqlclient-mysqldatareader-getchar.column as a single character.
*Note GetChars:                      Reads a stream of characters from
connector-net-ref-mysqlclient-mysqldatareader-getchars.the specified column offset into the
                                     buffer as an array starting at the
                                     given buffer offset.
*Note GetDataTypeName:               Gets the name of the source data
connector-net-ref-mysqlclient-mysqldatareader-getdatatypename.type.
*Note GetDateTime:                   
connector-net-ref-mysqlclient-mysqldatareader-getdatetime.
*Note GetDecimal:                    
connector-net-ref-mysqlclient-mysqldatareader-getdecimal.
*Note GetDouble:                     
connector-net-ref-mysqlclient-mysqldatareader-getdouble.
*Note GetFieldType:                  Gets the Type that is the data type
connector-net-ref-mysqlclient-mysqldatareader-getfieldtype.of the object.
*Note GetFloat:                      
connector-net-ref-mysqlclient-mysqldatareader-getfloat.
*Note GetGuid:                       
connector-net-ref-mysqlclient-mysqldatareader-getguid.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
*Note GetInt16:                      
connector-net-ref-mysqlclient-mysqldatareader-getint16.
*Note GetInt32:                      
connector-net-ref-mysqlclient-mysqldatareader-getint32.
*Note GetInt64:                      
connector-net-ref-mysqlclient-mysqldatareader-getint64.
GetLifetimeService(inherited from    Retrieves the current lifetime
MarshalByRefObject)                  service object that controls the
                                     lifetime policy for this instance.
*Note GetMySqlDateTime:              
connector-net-ref-mysqlclient-mysqldatareader-getmysqldatetime.
*Note GetName:                       Gets the name of the specified
connector-net-ref-mysqlclient-mysqldatareader-getname.column.
*Note GetOrdinal:                    Gets the column ordinal, given the
connector-net-ref-mysqlclient-mysqldatareader-getordinal.name of the column.
*Note GetSchemaTable:                Returns a DataTable that describes
connector-net-ref-mysqlclient-mysqldatareader-getschematable.the column metadata of the
                                     MySqlDataReader.
*Note GetString:                     
connector-net-ref-mysqlclient-mysqldatareader-getstring.
*Note GetTimeSpan:                   
connector-net-ref-mysqlclient-mysqldatareader-gettimespan.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
*Note GetUInt16:                     
connector-net-ref-mysqlclient-mysqldatareader-getuint16.
*Note GetUInt32:                     
connector-net-ref-mysqlclient-mysqldatareader-getuint32.
*Note GetUInt64:                     
connector-net-ref-mysqlclient-mysqldatareader-getuint64.
*Note GetValue:                      Gets the value of the specified
connector-net-ref-mysqlclient-mysqldatareader-getvalue.column in its native format.
*Note GetValues:                     Gets all attribute columns in the
connector-net-ref-mysqlclient-mysqldatareader-getvalues.collection for the current row.
InitializeLifetimeService(inherited  Obtains a lifetime service object
from MarshalByRefObject)             to control the lifetime policy for
                                     this instance.
*Note IsDBNull:                      Gets a value indicating whether the
connector-net-ref-mysqlclient-mysqldatareader-isdbnull.column contains non-existent or
                                     missing values.
*Note NextResult:                    Advances the data reader to the
connector-net-ref-mysqlclient-mysqldatareader-nextresult.next result, when reading the
                                     results of batch SQL statements.
*Note Read:                          Advances the MySqlDataReader to the
connector-net-ref-mysqlclient-mysqldatareader-read.next record.
ToString(inherited from Object)      Returns a Stringthat represents the
                                     current Object.

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-depth,  Next: connector-net-ref-mysqlclient-mysqldatareader-fieldcount,  Prev: connector-net-ref-mysqlclient-mysqldatareadermembers,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.115 Depth Property
.........................

Gets a value indicating the depth of nesting for the current row. This
method is not supported currently and always returns 0.

*Syntax: Visual Basic*

     NotOverridable Public ReadOnly Property Depth As Integer _
     _
       Implements IDataReader.Depth

*Syntax: C#*

     public int Depth {get;}

*Implements*

IDataReader.Depth

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-fieldcount,  Next: connector-net-ref-mysqlclient-mysqldatareader-hasrows,  Prev: connector-net-ref-mysqlclient-mysqldatareader-depth,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.116 FieldCount Property
..............................

Gets the number of columns in the current row.

*Syntax: Visual Basic*

     NotOverridable Public ReadOnly Property FieldCount As Integer _
     _
       Implements IDataRecord.FieldCount

*Syntax: C#*

     public int FieldCount {get;}

*Implements*

IDataRecord.FieldCount

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-hasrows,  Next: connector-net-ref-mysqlclient-mysqldatareader-isclosed,  Prev: connector-net-ref-mysqlclient-mysqldatareader-fieldcount,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.117 HasRows Property
...........................

Gets a value indicating whether the MySqlDataReader contains one or
more rows.

*Syntax: Visual Basic*

     Public ReadOnly Property HasRows As Boolean

*Syntax: C#*

     public bool HasRows {get;}

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-isclosed,  Next: connector-net-ref-mysqlclient-mysqldatareaderitem,  Prev: connector-net-ref-mysqlclient-mysqldatareader-hasrows,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.118 IsClosed Property
............................

Gets a value indicating whether the data reader is closed.

*Syntax: Visual Basic*

     NotOverridable Public ReadOnly Property IsClosed As Boolean _
     _
       Implements IDataReader.IsClosed

*Syntax: C#*

     public bool IsClosed {get;}

*Implements*

IDataReader.IsClosed

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareaderitem,  Next: connector-net-ref-mysqlclient-mysqldatareader-recordsaffected,  Prev: connector-net-ref-mysqlclient-mysqldatareader-isclosed,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.119 Item Property
........................

* Menu:

* connector-net-ref-mysqlclient-mysqldatareader-item1::  Item Property (Int32)
* connector-net-ref-mysqlclient-mysqldatareader-item2::  Item Property (String)

Overloaded. Gets the value of a column in its native format. In C#,
this property is the indexer for the MySqlDataReader class.

*Overload List*

Overloaded. Gets the value of a column in its native format. In C#,
this property is the indexer for the MySqlDataReader class.

   * *Note public object this[int] {get;}:
     connector-net-ref-mysqlclient-mysqldatareader-item1.

Gets the value of a column in its native format.  In C#, this property
is the indexer for the MySqlDataReader class.

   * *Note public object this[string] {get;}:
     connector-net-ref-mysqlclient-mysqldatareader-item2.

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-item1,  Next: connector-net-ref-mysqlclient-mysqldatareader-item2,  Prev: connector-net-ref-mysqlclient-mysqldatareaderitem,  Up: connector-net-ref-mysqlclient-mysqldatareaderitem

30.2.4.120 Item Property (Int32)
................................

Overloaded. Gets the value of a column in its native format. In C#,
this property is the indexer for the MySqlDataReader class.

*Syntax: Visual Basic*

     NotOverridable Overloads Public Default ReadOnly Property Item( _
        ByVal i As Integer _
     ) _
     _
       Implements IDataRecord.Item As Object _
     _
       Implements IDataRecord.Item

*Syntax: C#*

     public object this[
     inti
     ] {get;}

*Implements*

IDataRecord.Item

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlDataReader.Item Overload List:
connector-net-ref-mysqlclient-mysqldatareaderitem.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-item2,  Prev: connector-net-ref-mysqlclient-mysqldatareader-item1,  Up: connector-net-ref-mysqlclient-mysqldatareaderitem

30.2.4.121 Item Property (String)
.................................

Gets the value of a column in its native format.  In C#, this property
is the indexer for the MySqlDataReader class.

*Syntax: Visual Basic*

     NotOverridable Overloads Public Default ReadOnly Property Item( _
        ByVal name As String _
     ) _
     _
       Implements IDataRecord.Item As Object _
     _
       Implements IDataRecord.Item

*Syntax: C#*

     public object this[
     stringname
     ] {get;}

*Implements*

IDataRecord.Item

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlDataReader.Item Overload List:
connector-net-ref-mysqlclient-mysqldatareaderitem.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-recordsaffected,  Next: connector-net-ref-mysqlclient-mysqldatareader-close,  Prev: connector-net-ref-mysqlclient-mysqldatareaderitem,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.122 RecordsAffected Property
...................................

Gets the number of rows changed, inserted, or deleted by execution of
the SQL statement.

*Syntax: Visual Basic*

     NotOverridable Public ReadOnly Property RecordsAffected As Integer _
     _
       Implements IDataReader.RecordsAffected

*Syntax: C#*

     public int RecordsAffected {get;}

*Implements*

IDataReader.RecordsAffected

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-close,  Next: connector-net-ref-mysqlclient-mysqldatareader-getboolean,  Prev: connector-net-ref-mysqlclient-mysqldatareader-recordsaffected,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.123 `MySqlDataReader.Close' Method
.........................................

Closes the MySqlDataReader object.

*Syntax: Visual Basic*

     NotOverridable Public Sub Close() _
     _
       Implements IDataReader.Close

*Syntax: C#*

     public void Close();

*Implements*

IDataReader.Close

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getboolean,  Next: connector-net-ref-mysqlclient-mysqldatareader-getbyte,  Prev: connector-net-ref-mysqlclient-mysqldatareader-close,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.124 `MySqlDataReader.GetBoolean' Method
..............................................

Gets the value of the specified column as a Boolean.

*Syntax: Visual Basic*

     NotOverridable Public Function GetBoolean( _
        ByVal i As Integer _
     ) As Boolean _
     _
       Implements IDataRecord.GetBoolean

*Syntax: C#*

     public bool GetBoolean(
     inti
     );

*Parameters*

   * `i':

*Return Value*

*Implements*

IDataRecord.GetBoolean

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getbyte,  Next: connector-net-ref-mysqlclient-mysqldatareader-getbytes,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getboolean,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.125 `MySqlDataReader.GetByte' Method
...........................................

Gets the value of the specified column as a byte.

*Syntax: Visual Basic*

     NotOverridable Public Function GetByte( _
        ByVal i As Integer _
     ) As Byte _
     _
       Implements IDataRecord.GetByte

*Syntax: C#*

     public byte GetByte(
     inti
     );

*Parameters*

   * `i':

*Return Value*

*Implements*

IDataRecord.GetByte

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getbytes,  Next: connector-net-ref-mysqlclient-mysqldatareader-getchar,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getbyte,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.126 `MySqlDataReader.GetBytes' Method
............................................

Reads a stream of bytes from the specified column offset into the
buffer an array starting at the given buffer offset.

*Syntax: Visual Basic*

     NotOverridable Public Function GetBytes( _
        ByVal i As Integer, _
        ByVal dataIndex As Long, _
        ByVal buffer As Byte(), _
        ByVal bufferIndex As Integer, _
        ByVal length As Integer _
     ) As Long _
     _
       Implements IDataRecord.GetBytes

*Syntax: C#*

     public long GetBytes(
     inti,
     longdataIndex,
     byte[]buffer,
     intbufferIndex,
     intlength
     );

*Parameters*

   * `i': The zero-based column ordinal.

   * `dataIndex': The index within the field from which to begin the
     read operation.

   * `buffer': The buffer into which to read the stream of bytes.

   * `bufferIndex': The index for buffer to begin the read operation.

   * `length': The maximum length to copy into the buffer.

*Return Value*

The actual number of bytes read.

*Implements*

IDataRecord.GetBytes

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getchar,  Next: connector-net-ref-mysqlclient-mysqldatareader-getchars,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getbytes,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.127 `MySqlDataReader.GetChar' Method
...........................................

Gets the value of the specified column as a single character.

*Syntax: Visual Basic*

     NotOverridable Public Function GetChar( _
        ByVal i As Integer _
     ) As Char _
     _
       Implements IDataRecord.GetChar

*Syntax: C#*

     public char GetChar(
     inti
     );

*Parameters*

   * `i':

*Return Value*

*Implements*

IDataRecord.GetChar

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getchars,  Next: connector-net-ref-mysqlclient-mysqldatareader-getdatatypename,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getchar,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.128 `MySqlDataReader.GetChars' Method
............................................

Reads a stream of characters from the specified column offset into the
buffer as an array starting at the given buffer offset.

*Syntax: Visual Basic*

     NotOverridable Public Function GetChars( _
        ByVal i As Integer, _
        ByVal fieldOffset As Long, _
        ByVal buffer As Char(), _
        ByVal bufferoffset As Integer, _
        ByVal length As Integer _
     ) As Long _
     _
       Implements IDataRecord.GetChars

*Syntax: C#*

     public long GetChars(
     inti,
     longfieldOffset,
     char[]buffer,
     intbufferoffset,
     intlength
     );

*Parameters*

   * `i':

   * `fieldOffset':

   * `buffer':

   * `bufferoffset':

   * `length':

*Return Value*

*Implements*

IDataRecord.GetChars

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getdatatypename,  Next: connector-net-ref-mysqlclient-mysqldatareader-getdatetime,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getchars,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.129 `MySqlDataReader.GetDataTypeName' Method
...................................................

Gets the name of the source data type.

*Syntax: Visual Basic*

     NotOverridable Public Function GetDataTypeName( _
        ByVal i As Integer _
     ) As String _
     _
       Implements IDataRecord.GetDataTypeName

*Syntax: C#*

     public string GetDataTypeName(
     inti
     );

*Parameters*

   * `i':

*Return Value*

*Implements*

IDataRecord.GetDataTypeName

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getdatetime,  Next: connector-net-ref-mysqlclient-mysqldatareader-getdecimal,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getdatatypename,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.130 `MySqlDataReader.GetDateTime' Method
...............................................

*Syntax: Visual Basic*

     NotOverridable Public Function GetDateTime( _
        ByVal index As Integer _
     ) As Date _
     _
       Implements IDataRecord.GetDateTime

*Syntax: C#*

     public DateTime GetDateTime(
     intindex
     );

*Implements*

IDataRecord.GetDateTime

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getdecimal,  Next: connector-net-ref-mysqlclient-mysqldatareader-getdouble,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getdatetime,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.131 `MySqlDataReader.GetDecimal' Method
..............................................

*Syntax: Visual Basic*

     NotOverridable Public Function GetDecimal( _
        ByVal index As Integer _
     ) As Decimal _
     _
       Implements IDataRecord.GetDecimal

*Syntax: C#*

     public decimal GetDecimal(
     intindex
     );

*Implements*

IDataRecord.GetDecimal

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getdouble,  Next: connector-net-ref-mysqlclient-mysqldatareader-getfieldtype,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getdecimal,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.132 `MySqlDataReader.GetDouble' Method
.............................................

*Syntax: Visual Basic*

     NotOverridable Public Function GetDouble( _
        ByVal index As Integer _
     ) As Double _
     _
       Implements IDataRecord.GetDouble

*Syntax: C#*

     public double GetDouble(
     intindex
     );

*Implements*

IDataRecord.GetDouble

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getfieldtype,  Next: connector-net-ref-mysqlclient-mysqldatareader-getfloat,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getdouble,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.133 `MySqlDataReader.GetFieldType' Method
................................................

Gets the Type that is the data type of the object.

*Syntax: Visual Basic*

     NotOverridable Public Function GetFieldType( _
        ByVal i As Integer _
     ) As Type _
     _
       Implements IDataRecord.GetFieldType

*Syntax: C#*

     public Type GetFieldType(
     inti
     );

*Parameters*

   * `i':

*Return Value*

*Implements*

IDataRecord.GetFieldType

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getfloat,  Next: connector-net-ref-mysqlclient-mysqldatareader-getguid,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getfieldtype,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.134 `MySqlDataReader.GetFloat' Method
............................................

*Syntax: Visual Basic*

     NotOverridable Public Function GetFloat( _
        ByVal index As Integer _
     ) As Single _
     _
       Implements IDataRecord.GetFloat

*Syntax: C#*

     public float GetFloat(
     intindex
     );

*Implements*

IDataRecord.GetFloat

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getguid,  Next: connector-net-ref-mysqlclient-mysqldatareader-getint16,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getfloat,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.135 `MySqlDataReader.GetGuid' Method
...........................................

*Syntax: Visual Basic*

     NotOverridable Public Function GetGuid( _
        ByVal index As Integer _
     ) As Guid _
     _
       Implements IDataRecord.GetGuid

*Syntax: C#*

     public Guid GetGuid(
     intindex
     );

*Implements*

IDataRecord.GetGuid

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getint16,  Next: connector-net-ref-mysqlclient-mysqldatareader-getint32,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getguid,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.136 `MySqlDataReader.GetInt16' Method
............................................

*Syntax: Visual Basic*

     NotOverridable Public Function GetInt16( _
        ByVal index As Integer _
     ) As Short _
     _
       Implements IDataRecord.GetInt16

*Syntax: C#*

     public short GetInt16(
     intindex
     );

*Implements*

IDataRecord.GetInt16

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getint32,  Next: connector-net-ref-mysqlclient-mysqldatareader-getint64,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getint16,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.137 `MySqlDataReader.GetInt32' Method
............................................

*Syntax: Visual Basic*

     NotOverridable Public Function GetInt32( _
        ByVal index As Integer _
     ) As Integer _
     _
       Implements IDataRecord.GetInt32

*Syntax: C#*

     public int GetInt32(
     intindex
     );

*Implements*

IDataRecord.GetInt32

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getint64,  Next: connector-net-ref-mysqlclient-mysqldatareader-getmysqldatetime,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getint32,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.138 `MySqlDataReader.GetInt64' Method
............................................

*Syntax: Visual Basic*

     NotOverridable Public Function GetInt64( _
        ByVal index As Integer _
     ) As Long _
     _
       Implements IDataRecord.GetInt64

*Syntax: C#*

     public long GetInt64(
     intindex
     );

*Implements*

IDataRecord.GetInt64

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getmysqldatetime,  Next: connector-net-ref-mysqlclient-mysqldatareader-getname,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getint64,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.139 `MySqlDataReader.GetMySqlDateTime' Method
....................................................

*Syntax: Visual Basic*

     Public Function GetMySqlDateTime( _
        ByVal index As Integer _
     ) As MySqlDateTime

*Syntax: C#*

     public MySqlDateTime GetMySqlDateTime(
     intindex
     );

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getname,  Next: connector-net-ref-mysqlclient-mysqldatareader-getordinal,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getmysqldatetime,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.140 `MySqlDataReader.GetName' Method
...........................................

Gets the name of the specified column.

*Syntax: Visual Basic*

     NotOverridable Public Function GetName( _
        ByVal i As Integer _
     ) As String _
     _
       Implements IDataRecord.GetName

*Syntax: C#*

     public string GetName(
     inti
     );

*Parameters*

   * `i':

*Return Value*

*Implements*

IDataRecord.GetName

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getordinal,  Next: connector-net-ref-mysqlclient-mysqldatareader-getschematable,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getname,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.141 `MySqlDataReader.GetOrdinal' Method
..............................................

Gets the column ordinal, given the name of the column.

*Syntax: Visual Basic*

     NotOverridable Public Function GetOrdinal( _
        ByVal name As String _
     ) As Integer _
     _
       Implements IDataRecord.GetOrdinal

*Syntax: C#*

     public int GetOrdinal(
     stringname
     );

*Parameters*

   * `name':

*Return Value*

*Implements*

IDataRecord.GetOrdinal

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getschematable,  Next: connector-net-ref-mysqlclient-mysqldatareader-getstring,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getordinal,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.142 `MySqlDataReader.GetSchemaTable' Method
..................................................

Returns a DataTable that describes the column metadata of the
MySqlDataReader.

*Syntax: Visual Basic*

     NotOverridable Public Function GetSchemaTable() As DataTable _
     _
       Implements IDataReader.GetSchemaTable

*Syntax: C#*

     public DataTable GetSchemaTable();

*Return Value*

*Implements*

IDataReader.GetSchemaTable

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getstring,  Next: connector-net-ref-mysqlclient-mysqldatareader-gettimespan,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getschematable,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.143 `MySqlDataReader.GetString' Method
.............................................

*Syntax: Visual Basic*

     NotOverridable Public Function GetString( _
        ByVal index As Integer _
     ) As String _
     _
       Implements IDataRecord.GetString

*Syntax: C#*

     public string GetString(
     intindex
     );

*Implements*

IDataRecord.GetString

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-gettimespan,  Next: connector-net-ref-mysqlclient-mysqldatareader-getuint16,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getstring,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.144 `MySqlDataReader.GetTimeSpan' Method
...............................................

*Syntax: Visual Basic*

     Public Function GetTimeSpan( _
        ByVal index As Integer _
     ) As TimeSpan

*Syntax: C#*

     public TimeSpan GetTimeSpan(
     intindex
     );

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getuint16,  Next: connector-net-ref-mysqlclient-mysqldatareader-getuint32,  Prev: connector-net-ref-mysqlclient-mysqldatareader-gettimespan,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.145 `MySqlDataReader.GetUInt16' Method
.............................................

*Syntax: Visual Basic*

     Public Function GetUInt16( _
        ByVal index As Integer _
     ) As UInt16

*Syntax: C#*

     public ushort GetUInt16(
     intindex
     );

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getuint32,  Next: connector-net-ref-mysqlclient-mysqldatareader-getuint64,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getuint16,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.146 `MySqlDataReader.GetUInt32' Method
.............................................

*Syntax: Visual Basic*

     Public Function GetUInt32( _
        ByVal index As Integer _
     ) As UInt32

*Syntax: C#*

     public uint GetUInt32(
     intindex
     );

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getuint64,  Next: connector-net-ref-mysqlclient-mysqldatareader-getvalue,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getuint32,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.147 `MySqlDataReader.GetUInt64' Method
.............................................

*Syntax: Visual Basic*

     Public Function GetUInt64( _
        ByVal index As Integer _
     ) As UInt64

*Syntax: C#*

     public ulong GetUInt64(
     intindex
     );

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getvalue,  Next: connector-net-ref-mysqlclient-mysqldatareader-getvalues,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getuint64,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.148 `MySqlDataReader.GetValue' Method
............................................

Gets the value of the specified column in its native format.

*Syntax: Visual Basic*

     NotOverridable Public Function GetValue( _
        ByVal i As Integer _
     ) As Object _
     _
       Implements IDataRecord.GetValue

*Syntax: C#*

     public object GetValue(
     inti
     );

*Parameters*

   * `i':

*Return Value*

*Implements*

IDataRecord.GetValue

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-getvalues,  Next: connector-net-ref-mysqlclient-mysqldatareader-isdbnull,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getvalue,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.149 `MySqlDataReader.GetValues' Method
.............................................

Gets all attribute columns in the collection for the current row.

*Syntax: Visual Basic*

     NotOverridable Public Function GetValues( _
        ByVal values As Object() _
     ) As Integer _
     _
       Implements IDataRecord.GetValues

*Syntax: C#*

     public int GetValues(
     object[]values
     );

*Parameters*

   * `values':

*Return Value*

*Implements*

IDataRecord.GetValues

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-isdbnull,  Next: connector-net-ref-mysqlclient-mysqldatareader-nextresult,  Prev: connector-net-ref-mysqlclient-mysqldatareader-getvalues,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.150 `MySqlDataReader.IsDBNull' Method
............................................

Gets a value indicating whether the column contains non-existent or
missing values.

*Syntax: Visual Basic*

     NotOverridable Public Function IsDBNull( _
        ByVal i As Integer _
     ) As Boolean _
     _
       Implements IDataRecord.IsDBNull

*Syntax: C#*

     public bool IsDBNull(
     inti
     );

*Parameters*

   * `i':

*Return Value*

*Implements*

IDataRecord.IsDBNull

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-nextresult,  Next: connector-net-ref-mysqlclient-mysqldatareader-read,  Prev: connector-net-ref-mysqlclient-mysqldatareader-isdbnull,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.151 `MySqlDataReader.NextResult' Method
..............................................

Advances the data reader to the next result, when reading the results
of batch SQL statements.

*Syntax: Visual Basic*

     NotOverridable Public Function NextResult() As Boolean _
     _
       Implements IDataReader.NextResult

*Syntax: C#*

     public bool NextResult();

*Return Value*

*Implements*

IDataReader.NextResult

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldatareader-read,  Prev: connector-net-ref-mysqlclient-mysqldatareader-nextresult,  Up: connector-net-ref-mysqlclient-mysqldatareadermembers

30.2.4.152 `MySqlDataReader.Read' Method
........................................

Advances the MySqlDataReader to the next record.

*Syntax: Visual Basic*

     NotOverridable Public Function Read() As Boolean _
     _
       Implements IDataReader.Read

*Syntax: C#*

     public bool Read();

*Return Value*

*Implements*

IDataReader.Read

*See Also*

*Note MySqlDataReader Class:
connector-net-ref-mysqlclient-mysqldatareader , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-executereader-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlcommand-executereader-overload-1,  Up: connector-net-ref-mysqlclient-mysqlcommand-executereader-overloads

30.2.4.153 `MySqlCommand.ExecuteReader' Method
..............................................

*Syntax: Visual Basic*

     Overloads Public Function ExecuteReader( _
        ByVal behavior As CommandBehavior _
     ) As MySqlDataReader

*Syntax: C#*

     public MySqlDataReader ExecuteReader(
     CommandBehaviorbehavior
     );

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlCommand.ExecuteReader Overload List:
connector-net-ref-mysqlclient-mysqlcommand-executereader-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-executescalar,  Next: connector-net-ref-mysqlclient-mysqlcommand-prepare,  Prev: connector-net-ref-mysqlclient-mysqlcommand-executereader-overloads,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

30.2.4.154 `MySqlCommand.ExecuteScalar' Method
..............................................

*Syntax: Visual Basic*

     NotOverridable Public Function ExecuteScalar() As Object _
     _
       Implements IDbCommand.ExecuteScalar

*Syntax: C#*

     public object ExecuteScalar();

*Implements*

IDbCommand.ExecuteScalar

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommand-prepare,  Prev: connector-net-ref-mysqlclient-mysqlcommand-executescalar,  Up: connector-net-ref-mysqlclient-mysqlcommandmembers

30.2.4.155 `MySqlCommand.Prepare' Method
........................................

*Syntax: Visual Basic*

     NotOverridable Public Sub Prepare() _
     _
       Implements IDbCommand.Prepare

*Syntax: C#*

     public void Prepare();

*Implements*

IDbCommand.Prepare

*See Also*

*Note MySqlCommand Class: connector-net-ref-mysqlclient-mysqlcommand ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilder,  Next: connector-net-ref-mysqlclient-mysqlexception,  Prev: connector-net-ref-mysqlclient-mysqlcommand,  Up: connector-net-ref-mysqlclient

30.2.4.156 `MySqlCommandBuilder' Class
......................................

* Menu:

* connector-net-ref-mysqlclient-mysqlcommandbuildermembers::  `MySqlCommandBuilder' Members

For a list of all members of this type, see *Note MySqlCommandBuilder
Members: connector-net-ref-mysqlclient-mysqlcommandbuildermembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlCommandBuilder_
       Inherits Component

*Syntax: C#*

     public sealed class MySqlCommandBuilder : Component

*Thread Safety*

Public static (Sharedin Visual Basic) members of this type are safe for
multithreaded operations. Instance members are notguaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlCommandBuilder Members:
connector-net-ref-mysqlclient-mysqlcommandbuildermembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuildermembers,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilder,  Up: connector-net-ref-mysqlclient-mysqlcommandbuilder

30.2.4.157 `MySqlCommandBuilder' Members
........................................

* Menu:

* connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overloads::  DeriveParameters Method
* connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor::  `MySqlCommandBuilder' Constructor
* connector-net-ref-mysqlclient-mysqlcommandbuilder-dataadapter::  DataAdapter Property
* connector-net-ref-mysqlclient-mysqlcommandbuilder-quoteprefix::  QuotePrefix Property
* connector-net-ref-mysqlclient-mysqlcommandbuilder-quotesuffix::  QuoteSuffix Property
* connector-net-ref-mysqlclient-mysqlcommandbuilder-getdeletecommand::  `MySqlCommandBuilder.GetDeleteCommand' Method
* connector-net-ref-mysqlclient-mysqlcommandbuilder-getinsertcommand::  `MySqlCommandBuilder.GetInsertCommand' Method
* connector-net-ref-mysqlclient-mysqlcommandbuilder-getupdatecommand::  `MySqlCommandBuilder.GetUpdateCommand' Method
* connector-net-ref-mysqlclient-mysqlcommandbuilder-refreshschema::  `MySqlCommandBuilder.RefreshSchema' Method

*Note MySqlCommandBuilder overview:
connector-net-ref-mysqlclient-mysqlcommandbuilder.

*Public Static (Shared) Methods*

*Note DeriveParameters:              Overloaded. Retrieves parameter
connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overloads.information from the stored
                                     procedure specified in the
                                     MySqlCommand and populates the
                                     Parameters collection of the
                                     specified MySqlCommand object. This
                                     method is not currently supported
                                     since stored procedures are not
                                     available in MySql.

*Public Instance Constructors*

*Note MySqlCommandBuilder:           Overloaded. Initializes a new
connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor.instance of the MySqlCommandBuilder
                                     class.

*Public Instance Properties*

Container(inherited from Component)  Gets the IContainerthat contains
                                     the Component.
*Note DataAdapter:                   
connector-net-ref-mysqlclient-mysqlcommandbuilder-dataadapter.
*Note QuotePrefix:                   
connector-net-ref-mysqlclient-mysqlcommandbuilder-quoteprefix.
*Note QuoteSuffix:                   
connector-net-ref-mysqlclient-mysqlcommandbuilder-quotesuffix.
Site(inherited from Component)       Gets or sets the ISiteof the
                                     Component.

*Public Instance Methods*

CreateObjRef(inherited from          Creates an object that contains all
MarshalByRefObject)                  the relevant information required to
                                     generate a proxy used to
                                     communicate with a remote object.
Dispose(inherited from Component)    Releases all resources used by the
                                     Component.
Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
*Note GetDeleteCommand:              
connector-net-ref-mysqlclient-mysqlcommandbuilder-getdeletecommand.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
*Note GetInsertCommand:              
connector-net-ref-mysqlclient-mysqlcommandbuilder-getinsertcommand.
GetLifetimeService(inherited from    Retrieves the current lifetime
MarshalByRefObject)                  service object that controls the
                                     lifetime policy for this instance.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
*Note GetUpdateCommand:              
connector-net-ref-mysqlclient-mysqlcommandbuilder-getupdatecommand.
InitializeLifetimeService(inherited  Obtains a lifetime service object
from MarshalByRefObject)             to control the lifetime policy for
                                     this instance.
*Note RefreshSchema:                 
connector-net-ref-mysqlclient-mysqlcommandbuilder-refreshschema.
ToString(inherited from Component)   Returns a Stringcontaining the name
                                     of the Component, if any. This
                                     method should not be overridden.

*Public Instance Events*

Disposed(inherited from Component)   Adds an event handler to listen to
                                     the Disposedevent on the component.

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overloads,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuildermembers,  Up: connector-net-ref-mysqlclient-mysqlcommandbuildermembers

30.2.4.158 DeriveParameters Method
..................................

* Menu:

* connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overload-1::  `MySqlCommandBuilder.DeriveParameters' Method
* connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overload-2::  `MySqlCommandBuilder.DeriveParameters' Method

Retrieves parameter information from the stored procedure specified in
the MySqlCommand and populates the Parameters collection of the
specified MySqlCommand object. This method is not currently supported
since stored procedures are not available in MySql.

*Overload List*

Retrieves parameter information from the stored procedure specified in
the MySqlCommand and populates the Parameters collection of the
specified MySqlCommand object. This method is not currently supported
since stored procedures are not available in MySql.

   * *Note public static void DeriveParameters(MySqlCommand);:
     connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overload-1.

   * *Note public static void DeriveParameters(MySqlCommand:
     (bool);)connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overload-2.

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overload-1,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overloads,  Up: connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overloads

30.2.4.159 `MySqlCommandBuilder.DeriveParameters' Method
........................................................

Retrieves parameter information from the stored procedure specified in
the MySqlCommand and populates the Parameters collection of the
specified MySqlCommand object. This method is not currently supported
since stored procedures are not available in MySql.

*Syntax: Visual Basic*

     Overloads Public Shared Sub DeriveParameters( _
        ByVal command As MySqlCommand _
     )

*Syntax: C#*

     public static void DeriveParameters(
     MySqlCommandcommand
     );

*Parameters*

   * `command': The MySqlCommand referencing the stored procedure from
     which the parameter information is to be derived. The derived
     parameters are added to the Parameters collection of the
     MySqlCommand.

*Exceptions*

*Exception Type*                     *Condition*
InvalidOperationException            The command text is not a valid
                                     stored procedure name.

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlCommandBuilder.DeriveParameters Overload List:
connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overload-1,  Up: connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overloads

30.2.4.160 `MySqlCommandBuilder.DeriveParameters' Method
........................................................

*Syntax: Visual Basic*

     Overloads Public Shared Sub DeriveParameters( _
        ByVal command As MySqlCommand, _
        ByVal useProc As Boolean _
     )

*Syntax: C#*

     public static void DeriveParameters(
     MySqlCommandcommand,
     booluseProc
     );

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlCommandBuilder.DeriveParameters Overload List:
connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilder-dataadapter,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overloads,  Up: connector-net-ref-mysqlclient-mysqlcommandbuildermembers

30.2.4.161 `MySqlCommandBuilder' Constructor
............................................

* Menu:

* connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor1::  `MySqlCommandBuilder' Constructor
* connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor3::  `MySqlCommandBuilder' Constructor
* connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor4::  `MySqlCommandBuilder' Constructor
* connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor2::  `MySqlCommandBuilder' Constructor

Initializes a new instance of the *Note MySqlCommandBuilder:
connector-net-ref-mysqlclient-mysqlcommandbuilder.  class.

*Overload List*

Initializes a new instance of the *Note MySqlCommandBuilder:
connector-net-ref-mysqlclient-mysqlcommandbuilder.  class.

   * *Note public MySqlCommandBuilder();:
     connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor1.

   * *Note public MySqlCommandBuilder(MySqlDataAdapter);:
     connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor3.

   * *Note public MySqlCommandBuilder(MySqlDataAdapter:
     (bool);)connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor4.

   * *Note public MySqlCommandBuilder(bool);:
     connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor2.

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor1,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor3,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor,  Up: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor

30.2.4.162 `MySqlCommandBuilder' Constructor
............................................

Initializes a new instance of the *Note MySqlCommandBuilder:
connector-net-ref-mysqlclient-mysqlcommandbuilder.  class.

*Syntax: Visual Basic*

     Overloads Public Sub New()

*Syntax: C#*

     public MySqlCommandBuilder();

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlCommandBuilder Constructor Overload List:
connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor3,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor4,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor1,  Up: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor

30.2.4.163 `MySqlCommandBuilder' Constructor
............................................

* Menu:

* connector-net-ref-mysqlclient-mysqldataadapter::  `MySqlDataAdapter' Class

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal adapter As MySqlDataAdapter _
     )

*Syntax: C#*

     public MySqlCommandBuilder(
     MySqlDataAdapteradapter
     );

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlCommandBuilder Constructor Overload List:
connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapter,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor3,  Up: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor3

30.2.4.164 `MySqlDataAdapter' Class
...................................

* Menu:

* connector-net-ref-mysqlclient-mysqldataadaptermembers::  `MySqlDataAdapter' Members

For a list of all members of this type, see *Note MySqlDataAdapter
Members: connector-net-ref-mysqlclient-mysqldataadaptermembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlDataAdapter_
       Inherits DbDataAdapter

*Syntax: C#*

     public sealed class MySqlDataAdapter : DbDataAdapter

*Thread Safety*

Public static (Sharedin Visual Basic) members of this type are safe for
multithreaded operations. Instance members are notguaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlDataAdapter Members:
connector-net-ref-mysqlclient-mysqldataadaptermembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadaptermembers,  Prev: connector-net-ref-mysqlclient-mysqldataadapter,  Up: connector-net-ref-mysqlclient-mysqldataadapter

30.2.4.165 `MySqlDataAdapter' Members
.....................................

* Menu:

* connector-net-ref-mysqlclient-mysqldataadapterconstructor::  `MySqlDataAdapter' Constructor
* connector-net-ref-mysqlclient-mysqldataadapter-deletecommand1::  DeleteCommand Property
* connector-net-ref-mysqlclient-mysqldataadapter-insertcommand1::  InsertCommand Property
* connector-net-ref-mysqlclient-mysqldataadapter-selectcommand1::  SelectCommand Property
* connector-net-ref-mysqlclient-mysqldataadapter-updatecommand1::  UpdateCommand Property
* connector-net-ref-mysqlclient-mysqldataadapter-rowupdated::  `MySqlDataAdapter.RowUpdated' Event
* connector-net-ref-mysqlclient-mysqldataadapter-rowupdating::  `MySqlDataAdapter.RowUpdating' Event

*Note MySqlDataAdapter overview:
connector-net-ref-mysqlclient-mysqldataadapter.

*Public Instance Constructors*

*Note MySqlDataAdapter:              Overloaded. Initializes a new
connector-net-ref-mysqlclient-mysqldataadapterconstructor.instance of the MySqlDataAdapter
                                     class.

*Public Instance Properties*

AcceptChangesDuringFill(inherited    Gets or sets a value indicating
from DataAdapter)                    whether AcceptChangesis called on a
                                     DataRowafter it is added to the
                                     DataTableduring any of the Fill
                                     operations.
AcceptChangesDuringUpdate(inherited  Gets or sets whether
from DataAdapter)                    AcceptChangesis called during a
                                     Update.
Container(inherited from Component)  Gets the IContainerthat contains
                                     the Component.
ContinueUpdateOnError(inherited      Gets or sets a value that specifies
from DataAdapter)                    whether to generate an exception
                                     when an error is encountered during
                                     a row update.
*Note DeleteCommand:                 Overloaded.
connector-net-ref-mysqlclient-mysqldataadapter-deletecommand1.
FillLoadOption(inherited from        Gets or sets the LoadOptionthat
DataAdapter)                         determines how the adapter fills the
                                     DataTablefrom the DbDataReader.
*Note InsertCommand:                 Overloaded.
connector-net-ref-mysqlclient-mysqldataadapter-insertcommand1.
MissingMappingAction(inherited from  Determines the action to take when
DataAdapter)                         incoming data does not have a
                                     matching table or column.
MissingSchemaAction(inherited from   Determines the action to take when
DataAdapter)                         existing DataSetschema does not
                                     match incoming data.
ReturnProviderSpecificTypes(inheritedGets or sets whether the Fillmethod
from DataAdapter)                    should return provider-specific
                                     values or common CLS-compliant
                                     values.
*Note SelectCommand:                 Overloaded.
connector-net-ref-mysqlclient-mysqldataadapter-selectcommand1.
Site(inherited from Component)       Gets or sets the ISiteof the
                                     Component.
TableMappings(inherited from         Gets a collection that provides the
DataAdapter)                         master mapping between a source
                                     table and a DataTable.
UpdateBatchSize(inherited from       Gets or sets a value that enables
DbDataAdapter)                       or disables batch processing
                                     support, and specifies the number
                                     of commands that can be executed in
                                     a batch.
*Note UpdateCommand:                 Overloaded.
connector-net-ref-mysqlclient-mysqldataadapter-updatecommand1.

*Public Instance Methods*

CreateObjRef(inherited from          Creates an object that contains all
MarshalByRefObject)                  the relevant information required to
                                     generate a proxy used to
                                     communicate with a remote object.
Dispose(inherited from Component)    Releases all resources used by the
                                     Component.
Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
Fill(inherited from DbDataAdapter)   Overloaded. Adds or refreshes rows
                                     in the DataSetto match those in the
                                     data source using the DataSetname,
                                     and creates a DataTablenamed
                                     "Table."
FillSchema(inherited from            Overloaded. Configures the schema
DbDataAdapter)                       of the specified DataTablebased on
                                     the specified SchemaType.
GetFillParameters(inherited from     Gets the parameters set by the user
DbDataAdapter)                       when executing an SQL `SELECT'
                                     statement.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetLifetimeService(inherited from    Retrieves the current lifetime
MarshalByRefObject)                  service object that controls the
                                     lifetime policy for this instance.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
InitializeLifetimeService(inherited  Obtains a lifetime service object
from MarshalByRefObject)             to control the lifetime policy for
                                     this instance.
ResetFillLoadOption(inherited from   Resets FillLoadOptionto its default
DataAdapter)                         state and causes Fillto honor
                                     AcceptChangesDuringFill.
ShouldSerializeAcceptChangesDuringFill(inheritedDetermines whether the
from DataAdapter)                    AcceptChangesDuringFillproperty
                                     should be persisted.
ShouldSerializeFillLoadOption(inheritedDetermines whether the
from DataAdapter)                    FillLoadOptionproperty should be
                                     persisted.
ToString(inherited from Component)   Returns a Stringcontaining the name
                                     of the Component, if any. This
                                     method should not be overridden.
Update(inherited from DbDataAdapter) Overloaded. Calls the respective
                                     INSERT, UPDATE, or DELETE statements
                                     for each inserted, updated, or
                                     deleted row in the specified
                                     DataSet.

*Public Instance Events*

Disposed(inherited from Component)   Adds an event handler to listen to
                                     the Disposedevent on the component.
FillError(inherited from             Returned when an error occurs
DataAdapter)                         during a fill operation.
*Note RowUpdated:                    Occurs during Update after a
connector-net-ref-mysqlclient-mysqldataadapter-rowupdated.command is executed against the data
                                     source. The attempt to update is
                                     made, so the event fires.
*Note RowUpdating:                   Occurs during Update before a
connector-net-ref-mysqlclient-mysqldataadapter-rowupdating.command is executed against the data
                                     source. The attempt to update is
                                     made, so the event fires.

*Protected Internal Instance Properties*

FillCommandBehavior(inherited from   Gets or sets the behavior of the
DbDataAdapter)                       command used to fill the data
                                     adapter.

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapterconstructor,  Next: connector-net-ref-mysqlclient-mysqldataadapter-deletecommand1,  Prev: connector-net-ref-mysqlclient-mysqldataadaptermembers,  Up: connector-net-ref-mysqlclient-mysqldataadaptermembers

30.2.4.166 `MySqlDataAdapter' Constructor
.........................................

* Menu:

* connector-net-ref-mysqlclient-mysqldataadapterconstructor1::  `MySqlDataAdapter' Constructor
* connector-net-ref-mysqlclient-mysqldataadapterconstructor2::  `MySqlDataAdapter' Constructor
* connector-net-ref-mysqlclient-mysqldataadapterconstructor3::  `MySqlDataAdapter' Constructor
* connector-net-ref-mysqlclient-mysqldataadapterconstructor4::  `MySqlDataAdapter' Constructor

Initializes a new instance of the *Note MySqlDataAdapter:
connector-net-ref-mysqlclient-mysqldataadapter.  class.

*Overload List*

Initializes a new instance of the *Note MySqlDataAdapter:
connector-net-ref-mysqlclient-mysqldataadapter.  class.

   * *Note public MySqlDataAdapter();:
     connector-net-ref-mysqlclient-mysqldataadapterconstructor1.

   * *Note public MySqlDataAdapter(MySqlCommand);:
     connector-net-ref-mysqlclient-mysqldataadapterconstructor2.

   * *Note public MySqlDataAdapter(string:
     (MySqlConnection);)connector-net-ref-mysqlclient-mysqldataadapterconstructor3.

   * *Note public MySqlDataAdapter(string:
     (string);)connector-net-ref-mysqlclient-mysqldataadapterconstructor4.

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapterconstructor1,  Next: connector-net-ref-mysqlclient-mysqldataadapterconstructor2,  Prev: connector-net-ref-mysqlclient-mysqldataadapterconstructor,  Up: connector-net-ref-mysqlclient-mysqldataadapterconstructor

30.2.4.167 `MySqlDataAdapter' Constructor
.........................................

Initializes a new instance of the *Note MySqlDataAdapter:
connector-net-ref-mysqlclient-mysqldataadapter.  class.

*Syntax: Visual Basic*

     Overloads Public Sub New()

*Syntax: C#*

     public MySqlDataAdapter();

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlDataAdapter Constructor Overload List:
connector-net-ref-mysqlclient-mysqldataadapterconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapterconstructor2,  Next: connector-net-ref-mysqlclient-mysqldataadapterconstructor3,  Prev: connector-net-ref-mysqlclient-mysqldataadapterconstructor1,  Up: connector-net-ref-mysqlclient-mysqldataadapterconstructor

30.2.4.168 `MySqlDataAdapter' Constructor
.........................................

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal selectCommand As MySqlCommand _
     )

*Syntax: C#*

     public MySqlDataAdapter(
     MySqlCommandselectCommand
     );

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlDataAdapter Constructor Overload List:
connector-net-ref-mysqlclient-mysqldataadapterconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapterconstructor3,  Next: connector-net-ref-mysqlclient-mysqldataadapterconstructor4,  Prev: connector-net-ref-mysqlclient-mysqldataadapterconstructor2,  Up: connector-net-ref-mysqlclient-mysqldataadapterconstructor

30.2.4.169 `MySqlDataAdapter' Constructor
.........................................

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal selectCommandText As String, _
        ByVal connection As MySqlConnection _
     )

*Syntax: C#*

     public MySqlDataAdapter(
     stringselectCommandText,
     MySqlConnectionconnection
     );

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlDataAdapter Constructor Overload List:
connector-net-ref-mysqlclient-mysqldataadapterconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapterconstructor4,  Prev: connector-net-ref-mysqlclient-mysqldataadapterconstructor3,  Up: connector-net-ref-mysqlclient-mysqldataadapterconstructor

30.2.4.170 `MySqlDataAdapter' Constructor
.........................................

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal selectCommandText As String, _
        ByVal selectConnString As String _
     )

*Syntax: C#*

     public MySqlDataAdapter(
     stringselectCommandText,
     stringselectConnString
     );

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlDataAdapter Constructor Overload List:
connector-net-ref-mysqlclient-mysqldataadapterconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapter-deletecommand1,  Next: connector-net-ref-mysqlclient-mysqldataadapter-insertcommand1,  Prev: connector-net-ref-mysqlclient-mysqldataadapterconstructor,  Up: connector-net-ref-mysqlclient-mysqldataadaptermembers

30.2.4.171 DeleteCommand Property
.................................

*Syntax: Visual Basic*

     Overloads Public Property DeleteCommand As MySqlCommand

*Syntax: C#*

     new public MySqlCommand DeleteCommand {get; set;}

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapter-insertcommand1,  Next: connector-net-ref-mysqlclient-mysqldataadapter-selectcommand1,  Prev: connector-net-ref-mysqlclient-mysqldataadapter-deletecommand1,  Up: connector-net-ref-mysqlclient-mysqldataadaptermembers

30.2.4.172 InsertCommand Property
.................................

*Syntax: Visual Basic*

     Overloads Public Property InsertCommand As MySqlCommand

*Syntax: C#*

     new public MySqlCommand InsertCommand {get; set;}

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapter-selectcommand1,  Next: connector-net-ref-mysqlclient-mysqldataadapter-updatecommand1,  Prev: connector-net-ref-mysqlclient-mysqldataadapter-insertcommand1,  Up: connector-net-ref-mysqlclient-mysqldataadaptermembers

30.2.4.173 SelectCommand Property
.................................

*Syntax: Visual Basic*

     Overloads Public Property SelectCommand As MySqlCommand

*Syntax: C#*

     new public MySqlCommand SelectCommand {get; set;}

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapter-updatecommand1,  Next: connector-net-ref-mysqlclient-mysqldataadapter-rowupdated,  Prev: connector-net-ref-mysqlclient-mysqldataadapter-selectcommand1,  Up: connector-net-ref-mysqlclient-mysqldataadaptermembers

30.2.4.174 UpdateCommand Property
.................................

*Syntax: Visual Basic*

     Overloads Public Property UpdateCommand As MySqlCommand

*Syntax: C#*

     new public MySqlCommand UpdateCommand {get; set;}

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapter-rowupdated,  Next: connector-net-ref-mysqlclient-mysqldataadapter-rowupdating,  Prev: connector-net-ref-mysqlclient-mysqldataadapter-updatecommand1,  Up: connector-net-ref-mysqlclient-mysqldataadaptermembers

30.2.4.175 `MySqlDataAdapter.RowUpdated' Event
..............................................

* Menu:

* connector-net-ref-mysqlclient-mysqlrowupdatedeventhandler::  `MySqlRowUpdatedEventHandler' Delegate

Occurs during Update after a command is executed against the data
source. The attempt to update is made, so the event fires.

*Syntax: Visual Basic*

     Public Event RowUpdated As MySqlRowUpdatedEventHandler

*Syntax: C#*

     public event MySqlRowUpdatedEventHandler RowUpdated;

*Event Data*

The event handler receives an argument of type *Note
MySqlRowUpdatedEventArgs:
connector-net-ref-mysqlclient-mysqlrowupdatedeventargs.  containing
data related to this event. The following
MySqlRowUpdatedEventArgsproperties provide information specific to this
event.

*Property*                           *Description*
*Note Command:                       Gets or sets the MySqlCommand
connector-net-ref-mysqlclient-mysqlrowupdatedeventargs-command1.executed when Update is called.
Errors                               Gets any errors generated by the
                                     .NET Framework data provider when
                                     the Commandwas executed.
RecordsAffected                      Gets the number of rows changed,
                                     inserted, or deleted by execution of
                                     the SQL statement.
Row                                  Gets the DataRowsent through an
                                     Update.
RowCount                             Gets the number of rows processed
                                     in a batch of updated records.
StatementType                        Gets the type of SQL statement
                                     executed.
Status                               Gets the UpdateStatusof the
                                     Commandproperty.
TableMapping                         Gets the DataTableMappingsent
                                     through an Update.

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlrowupdatedeventhandler,  Prev: connector-net-ref-mysqlclient-mysqldataadapter-rowupdated,  Up: connector-net-ref-mysqlclient-mysqldataadapter-rowupdated

30.2.4.176 `MySqlRowUpdatedEventHandler' Delegate
.................................................

* Menu:

* connector-net-ref-mysqlclient-mysqlrowupdatedeventargs::  `MySqlRowUpdatedEventArgs' Class

Represents the method that will handle the RowUpdatedevent of a *Note
MySqlDataAdapter: connector-net-ref-mysqlclient-mysqldataadapter .

*Syntax: Visual Basic*

     Public Delegate Sub MySqlRowUpdatedEventHandler( _
        ByVal sender As Object, _
        ByVal e As MySqlRowUpdatedEventArgs _
     )

*Syntax: C#*

     public delegate void MySqlRowUpdatedEventHandler(
     objectsender,
     MySqlRowUpdatedEventArgse
     );

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlrowupdatedeventargs,  Prev: connector-net-ref-mysqlclient-mysqlrowupdatedeventhandler,  Up: connector-net-ref-mysqlclient-mysqlrowupdatedeventhandler

30.2.4.177 `MySqlRowUpdatedEventArgs' Class
...........................................

* Menu:

* connector-net-ref-mysqlclient-mysqlrowupdatedeventargsmembers::  `MySqlRowUpdatedEventArgs' Members

Provides data for the RowUpdated event. This class cannot be inherited.

For a list of all members of this type, see *Note
MySqlRowUpdatedEventArgs Members:
connector-net-ref-mysqlclient-mysqlrowupdatedeventargsmembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlRowUpdatedEventArgs_
       Inherits RowUpdatedEventArgs

*Syntax: C#*

     public sealed class MySqlRowUpdatedEventArgs : RowUpdatedEventArgs

*Thread Safety*

Public static (Sharedin Visual Basic) members of this type are safe for
multithreaded operations. Instance members are notguaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlRowUpdatedEventArgs Members:
connector-net-ref-mysqlclient-mysqlrowupdatedeventargsmembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlrowupdatedeventargsmembers,  Prev: connector-net-ref-mysqlclient-mysqlrowupdatedeventargs,  Up: connector-net-ref-mysqlclient-mysqlrowupdatedeventargs

30.2.4.178 `MySqlRowUpdatedEventArgs' Members
.............................................

* Menu:

* connector-net-ref-mysqlclient-mysqlrowupdatedeventargsconstructor::  `MySqlRowUpdatedEventArgs' Constructor
* connector-net-ref-mysqlclient-mysqlrowupdatedeventargs-command1::  Command Property

*Note MySqlRowUpdatedEventArgs overview:
connector-net-ref-mysqlclient-mysqlrowupdatedeventargs.

*Public Instance Constructors*

*Note MySqlRowUpdatedEventArgs       Initializes a new instance of the
Constructor:                         MySqlRowUpdatedEventArgs class.
connector-net-ref-mysqlclient-mysqlrowupdatedeventargsconstructor.

*Public Instance Properties*

*Note Command:                       Overloaded. Gets or sets the
connector-net-ref-mysqlclient-mysqlrowupdatedeventargs-command1.MySqlCommand executed when Update is
                                     called.
Errors(inherited from                Gets any errors generated by the
RowUpdatedEventArgs)                 .NET Framework data provider when
                                     the Commandwas executed.
RecordsAffected(inherited from       Gets the number of rows changed,
RowUpdatedEventArgs)                 inserted, or deleted by execution of
                                     the SQL statement.
Row(inherited from                   Gets the DataRowsent through an
RowUpdatedEventArgs)                 Update.
RowCount(inherited from              Gets the number of rows processed
RowUpdatedEventArgs)                 in a batch of updated records.
StatementType(inherited from         Gets the type of SQL statement
RowUpdatedEventArgs)                 executed.
Status(inherited from                Gets the UpdateStatusof the
RowUpdatedEventArgs)                 Commandproperty.
TableMapping(inherited from          Gets the DataTableMappingsent
RowUpdatedEventArgs)                 through an Update.

*Public Instance Methods*

CopyToRows(inherited from            Overloaded. Copies references to
RowUpdatedEventArgs)                 the modified rows into the provided
                                     array.
Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
ToString(inherited from Object)      Returns a Stringthat represents the
                                     current Object.

*See Also*

*Note MySqlRowUpdatedEventArgs Class:
connector-net-ref-mysqlclient-mysqlrowupdatedeventargs , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlrowupdatedeventargsconstructor,  Next: connector-net-ref-mysqlclient-mysqlrowupdatedeventargs-command1,  Prev: connector-net-ref-mysqlclient-mysqlrowupdatedeventargsmembers,  Up: connector-net-ref-mysqlclient-mysqlrowupdatedeventargsmembers

30.2.4.179 `MySqlRowUpdatedEventArgs' Constructor
.................................................

Initializes a new instance of the MySqlRowUpdatedEventArgs class.

*Syntax: Visual Basic*

     Public Sub New( _
        ByVal row As DataRow, _
        ByVal command As IDbCommand, _
        ByVal statementType As StatementType, _
        ByVal tableMapping As DataTableMapping _
     )

*Syntax: C#*

     public MySqlRowUpdatedEventArgs(
     DataRowrow,
     IDbCommandcommand,
     StatementTypestatementType,
     DataTableMappingtableMapping
     );

*Parameters*

   * `row': The DataRowsent through an Update.

   * `command': The IDbCommandexecuted when Updateis called.

   * `statementType': One of the StatementTypevalues that specifies the
     type of query executed.

   * `tableMapping': The DataTableMappingsent through an Update.

*See Also*

*Note MySqlRowUpdatedEventArgs Class:
connector-net-ref-mysqlclient-mysqlrowupdatedeventargs , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlrowupdatedeventargs-command1,  Prev: connector-net-ref-mysqlclient-mysqlrowupdatedeventargsconstructor,  Up: connector-net-ref-mysqlclient-mysqlrowupdatedeventargsmembers

30.2.4.180 Command Property
...........................

Gets or sets the MySqlCommand executed when Update is called.

*Syntax: Visual Basic*

     Overloads Public ReadOnly Property Command As MySqlCommand

*Syntax: C#*

     new public MySqlCommand Command {get;}

*See Also*

*Note MySqlRowUpdatedEventArgs Class:
connector-net-ref-mysqlclient-mysqlrowupdatedeventargs , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqldataadapter-rowupdating,  Prev: connector-net-ref-mysqlclient-mysqldataadapter-rowupdated,  Up: connector-net-ref-mysqlclient-mysqldataadaptermembers

30.2.4.181 `MySqlDataAdapter.RowUpdating' Event
...............................................

* Menu:

* connector-net-ref-mysqlclient-mysqlrowupdatingeventhandler::  `MySqlRowUpdatingEventHandler' Delegate

Occurs during Update before a command is executed against the data
source. The attempt to update is made, so the event fires.

*Syntax: Visual Basic*

     Public Event RowUpdating As MySqlRowUpdatingEventHandler

*Syntax: C#*

     public event MySqlRowUpdatingEventHandler RowUpdating;

*Event Data*

The event handler receives an argument of type *Note
MySqlRowUpdatingEventArgs:
connector-net-ref-mysqlclient-mysqlrowupdatingeventargs.  containing
data related to this event. The following
MySqlRowUpdatingEventArgsproperties provide information specific to
this event.

*Property*                           *Description*
*Note Command:                       Gets or sets the MySqlCommand to
connector-net-ref-mysqlclient-mysqlrowupdatingeventargs-command1.execute when performing the Update.
Errors                               Gets any errors generated by the
                                     .NET Framework data provider when
                                     the Commandexecutes.
Row                                  Gets the DataRowthat will be sent
                                     to the server as part of an insert,
                                     update, or delete operation.
StatementType                        Gets the type of SQL statement to
                                     execute.
Status                               Gets or sets the UpdateStatusof the
                                     Commandproperty.
TableMapping                         Gets the DataTableMappingto send
                                     through the Update.

*See Also*

*Note MySqlDataAdapter Class:
connector-net-ref-mysqlclient-mysqldataadapter , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlrowupdatingeventhandler,  Prev: connector-net-ref-mysqlclient-mysqldataadapter-rowupdating,  Up: connector-net-ref-mysqlclient-mysqldataadapter-rowupdating

30.2.4.182 `MySqlRowUpdatingEventHandler' Delegate
..................................................

* Menu:

* connector-net-ref-mysqlclient-mysqlrowupdatingeventargs::  `MySqlRowUpdatingEventArgs' Class

Represents the method that will handle the RowUpdatingevent of a *Note
MySqlDataAdapter: connector-net-ref-mysqlclient-mysqldataadapter .

*Syntax: Visual Basic*

     Public Delegate Sub MySqlRowUpdatingEventHandler( _
        ByVal sender As Object, _
        ByVal e As MySqlRowUpdatingEventArgs _
     )

*Syntax: C#*

     public delegate void MySqlRowUpdatingEventHandler(
     objectsender,
     MySqlRowUpdatingEventArgse
     );

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlrowupdatingeventargs,  Prev: connector-net-ref-mysqlclient-mysqlrowupdatingeventhandler,  Up: connector-net-ref-mysqlclient-mysqlrowupdatingeventhandler

30.2.4.183 `MySqlRowUpdatingEventArgs' Class
............................................

* Menu:

* connector-net-ref-mysqlclient-mysqlrowupdatingeventargsmembers::  `MySqlRowUpdatingEventArgs' Members

Provides data for the RowUpdating event. This class cannot be inherited.

For a list of all members of this type, see *Note
MySqlRowUpdatingEventArgs Members:
connector-net-ref-mysqlclient-mysqlrowupdatingeventargsmembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlRowUpdatingEventArgs_
       Inherits RowUpdatingEventArgs

*Syntax: C#*

     public sealed class MySqlRowUpdatingEventArgs : RowUpdatingEventArgs

*Thread Safety*

Public static (Sharedin Visual Basic) members of this type are safe for
multithreaded operations. Instance members are notguaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlRowUpdatingEventArgs Members:
connector-net-ref-mysqlclient-mysqlrowupdatingeventargsmembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlrowupdatingeventargsmembers,  Prev: connector-net-ref-mysqlclient-mysqlrowupdatingeventargs,  Up: connector-net-ref-mysqlclient-mysqlrowupdatingeventargs

30.2.4.184 `MySqlRowUpdatingEventArgs' Members
..............................................

* Menu:

* connector-net-ref-mysqlclient-mysqlrowupdatingeventargsconstructor::  `MySqlRowUpdatingEventArgs' Constructor
* connector-net-ref-mysqlclient-mysqlrowupdatingeventargs-command1::  Command Property

*Note MySqlRowUpdatingEventArgs overview:
connector-net-ref-mysqlclient-mysqlrowupdatingeventargs.

*Public Instance Constructors*

*Note MySqlRowUpdatingEventArgs      Initializes a new instance of the
Constructor:                         MySqlRowUpdatingEventArgs class.
connector-net-ref-mysqlclient-mysqlrowupdatingeventargsconstructor.

*Public Instance Properties*

*Note Command:                       Overloaded. Gets or sets the
connector-net-ref-mysqlclient-mysqlrowupdatingeventargs-command1.MySqlCommand to execute when
                                     performing the Update.
Errors(inherited from                Gets any errors generated by the
RowUpdatingEventArgs)                .NET Framework data provider when
                                     the Commandexecutes.
Row(inherited from                   Gets the DataRowthat will be sent
RowUpdatingEventArgs)                to the server as part of an insert,
                                     update, or delete operation.
StatementType(inherited from         Gets the type of SQL statement to
RowUpdatingEventArgs)                execute.
Status(inherited from                Gets or sets the UpdateStatusof the
RowUpdatingEventArgs)                Commandproperty.
TableMapping(inherited from          Gets the DataTableMappingto send
RowUpdatingEventArgs)                through the Update.

*Public Instance Methods*

Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
ToString(inherited from Object)      Returns a Stringthat represents the
                                     current Object.

*See Also*

*Note MySqlRowUpdatingEventArgs Class:
connector-net-ref-mysqlclient-mysqlrowupdatingeventargs , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlrowupdatingeventargsconstructor,  Next: connector-net-ref-mysqlclient-mysqlrowupdatingeventargs-command1,  Prev: connector-net-ref-mysqlclient-mysqlrowupdatingeventargsmembers,  Up: connector-net-ref-mysqlclient-mysqlrowupdatingeventargsmembers

30.2.4.185 `MySqlRowUpdatingEventArgs' Constructor
..................................................

Initializes a new instance of the MySqlRowUpdatingEventArgs class.

*Syntax: Visual Basic*

     Public Sub New( _
        ByVal row As DataRow, _
        ByVal command As IDbCommand, _
        ByVal statementType As StatementType, _
        ByVal tableMapping As DataTableMapping _
     )

*Syntax: C#*

     public MySqlRowUpdatingEventArgs(
     DataRowrow,
     IDbCommandcommand,
     StatementTypestatementType,
     DataTableMappingtableMapping
     );

*Parameters*

   * `row': The DataRowto Update.

   * `command': The IDbCommandto execute during Update.

   * `statementType': One of the StatementTypevalues that specifies the
     type of query executed.

   * `tableMapping': The DataTableMappingsent through an Update.

*See Also*

*Note MySqlRowUpdatingEventArgs Class:
connector-net-ref-mysqlclient-mysqlrowupdatingeventargs , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlrowupdatingeventargs-command1,  Prev: connector-net-ref-mysqlclient-mysqlrowupdatingeventargsconstructor,  Up: connector-net-ref-mysqlclient-mysqlrowupdatingeventargsmembers

30.2.4.186 Command Property
...........................

Gets or sets the MySqlCommand to execute when performing the Update.

*Syntax: Visual Basic*

     Overloads Public Property Command As MySqlCommand

*Syntax: C#*

     new public MySqlCommand Command {get; set;}

*See Also*

*Note MySqlRowUpdatingEventArgs Class:
connector-net-ref-mysqlclient-mysqlrowupdatingeventargs , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor4,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor2,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor3,  Up: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor

30.2.4.187 `MySqlCommandBuilder' Constructor
............................................

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal adapter As MySqlDataAdapter, _
        ByVal lastOneWins As Boolean _
     )

*Syntax: C#*

     public MySqlCommandBuilder(
     MySqlDataAdapteradapter,
     boollastOneWins
     );

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlCommandBuilder Constructor Overload List:
connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor2,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor4,  Up: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor

30.2.4.188 `MySqlCommandBuilder' Constructor
............................................

*Syntax: Visual Basic*

     Overloads Public Sub New( _
        ByVal lastOneWins As Boolean _
     )

*Syntax: C#*

     public MySqlCommandBuilder(
     boollastOneWins
     );

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient , *Note
MySqlCommandBuilder Constructor Overload List:
connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-dataadapter,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilder-quoteprefix,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor,  Up: connector-net-ref-mysqlclient-mysqlcommandbuildermembers

30.2.4.189 DataAdapter Property
...............................

*Syntax: Visual Basic*

     Public Property DataAdapter As MySqlDataAdapter

*Syntax: C#*

     public MySqlDataAdapter DataAdapter {get; set;}

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-quoteprefix,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilder-quotesuffix,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilder-dataadapter,  Up: connector-net-ref-mysqlclient-mysqlcommandbuildermembers

30.2.4.190 QuotePrefix Property
...............................

*Syntax: Visual Basic*

     Public Property QuotePrefix As String

*Syntax: C#*

     public string QuotePrefix {get; set;}

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-quotesuffix,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilder-getdeletecommand,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilder-quoteprefix,  Up: connector-net-ref-mysqlclient-mysqlcommandbuildermembers

30.2.4.191 QuoteSuffix Property
...............................

*Syntax: Visual Basic*

     Public Property QuoteSuffix As String

*Syntax: C#*

     public string QuoteSuffix {get; set;}

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-getdeletecommand,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilder-getinsertcommand,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilder-quotesuffix,  Up: connector-net-ref-mysqlclient-mysqlcommandbuildermembers

30.2.4.192 `MySqlCommandBuilder.GetDeleteCommand' Method
........................................................

*Syntax: Visual Basic*

     Public Function GetDeleteCommand() As MySqlCommand

*Syntax: C#*

     public MySqlCommand GetDeleteCommand();

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-getinsertcommand,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilder-getupdatecommand,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilder-getdeletecommand,  Up: connector-net-ref-mysqlclient-mysqlcommandbuildermembers

30.2.4.193 `MySqlCommandBuilder.GetInsertCommand' Method
........................................................

*Syntax: Visual Basic*

     Public Function GetInsertCommand() As MySqlCommand

*Syntax: C#*

     public MySqlCommand GetInsertCommand();

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-getupdatecommand,  Next: connector-net-ref-mysqlclient-mysqlcommandbuilder-refreshschema,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilder-getinsertcommand,  Up: connector-net-ref-mysqlclient-mysqlcommandbuildermembers

30.2.4.194 `MySqlCommandBuilder.GetUpdateCommand' Method
........................................................

*Syntax: Visual Basic*

     Public Function GetUpdateCommand() As MySqlCommand

*Syntax: C#*

     public MySqlCommand GetUpdateCommand();

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-refreshschema,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilder-getupdatecommand,  Up: connector-net-ref-mysqlclient-mysqlcommandbuildermembers

30.2.4.195 `MySqlCommandBuilder.RefreshSchema' Method
.....................................................

*Syntax: Visual Basic*

     Public Sub RefreshSchema()

*Syntax: C#*

     public void RefreshSchema();

*See Also*

*Note MySqlCommandBuilder Class:
connector-net-ref-mysqlclient-mysqlcommandbuilder , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlexception,  Next: connector-net-ref-mysqlclient-mysqlhelper,  Prev: connector-net-ref-mysqlclient-mysqlcommandbuilder,  Up: connector-net-ref-mysqlclient

30.2.4.196 `MySqlException' Class
.................................

* Menu:

* connector-net-ref-mysqlclient-mysqlexceptionmembers::  `MySqlException' Members

The exception that is thrown when MySQL returns an error. This class
cannot be inherited.

For a list of all members of this type, see *Note MySqlException
Members: connector-net-ref-mysqlclient-mysqlexceptionmembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlException_
       Inherits SystemException

*Syntax: C#*

     public sealed class MySqlException : SystemException

*Thread Safety*

Public static (Sharedin Visual Basic) members of this type are safe for
multithreaded operations. Instance members are notguaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlException Members:
connector-net-ref-mysqlclient-mysqlexceptionmembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlexceptionmembers,  Prev: connector-net-ref-mysqlclient-mysqlexception,  Up: connector-net-ref-mysqlclient-mysqlexception

30.2.4.197 `MySqlException' Members
...................................

* Menu:

* connector-net-ref-mysqlclient-mysqlexception-number::  Number Property

*Note MySqlException overview:
connector-net-ref-mysqlclient-mysqlexception.

*Public Instance Properties*

Data(inherited from Exception)       Gets a collection of key/value
                                     pairs that provide additional,
                                     user-defined information about the
                                     exception.
HelpLink(inherited from Exception)   Gets or sets a link to the help
                                     file associated with this exception.
InnerException(inherited from        Gets the Exceptioninstance that
Exception)                           caused the current exception.
Message(inherited from Exception)    Gets a message that describes the
                                     current exception.
*Note Number:                        Gets a number that identifies the
connector-net-ref-mysqlclient-mysqlexception-number.type of error.
Source(inherited from Exception)     Gets or sets the name of the
                                     application or the object that
                                     causes the error.
StackTrace(inherited from Exception) Gets a string representation of the
                                     frames on the call stack at the time
                                     the current exception was thrown.
TargetSite(inherited from Exception) Gets the method that throws the
                                     current exception.

*Public Instance Methods*

Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetBaseException(inherited from      When overridden in a derived class,
Exception)                           returns the Exceptionthat is the
                                     root cause of one or more
                                     subsequent exceptions.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetObjectData(inherited from         When overridden in a derived class,
Exception)                           sets the SerializationInfowith
                                     information about the exception.
GetType(inherited from Exception)    Gets the runtime type of the
                                     current instance.
ToString(inherited from Exception)   Creates and returns a string
                                     representation of the current
                                     exception.

*See Also*

*Note MySqlException Class:
connector-net-ref-mysqlclient-mysqlexception , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlexception-number,  Prev: connector-net-ref-mysqlclient-mysqlexceptionmembers,  Up: connector-net-ref-mysqlclient-mysqlexceptionmembers

30.2.4.198 Number Property
..........................

Gets a number that identifies the type of error.

*Syntax: Visual Basic*

     Public ReadOnly Property Number As Integer

*Syntax: C#*

     public int Number {get;}

*See Also*

*Note MySqlException Class:
connector-net-ref-mysqlclient-mysqlexception , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper,  Next: connector-net-ref-mysqlclient-mysqlerrorcode,  Prev: connector-net-ref-mysqlclient-mysqlexception,  Up: connector-net-ref-mysqlclient

30.2.4.199 `MySqlHelper' Class
..............................

* Menu:

* connector-net-ref-mysqlclient-mysqlhelpermembers::  `MySqlHelper' Members

Helper class that makes it easier to work with the provider.

For a list of all members of this type, see *Note MySqlHelper Members:
connector-net-ref-mysqlclient-mysqlhelpermembers .

*Syntax: Visual Basic*

     NotInheritable Public Class MySqlHelper

*Syntax: C#*

     public sealed class MySqlHelper

*Thread Safety*

Public static (Shared in Visual Basic) members of this type are safe
for multithreaded operations. Instance members are not guaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlHelper Members:
connector-net-ref-mysqlclient-mysqlhelpermembers , *Note
MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelpermembers,  Prev: connector-net-ref-mysqlclient-mysqlhelper,  Up: connector-net-ref-mysqlclient-mysqlhelper

30.2.4.200 `MySqlHelper' Members
................................

* Menu:

* connector-net-ref-mysqlclient-mysqlhelper-executedatarow::  `MySqlHelper.ExecuteDataRow' Method
* connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads::  ExecuteDataset Method
* connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overloads::  ExecuteNonQuery Method
* connector-net-ref-mysqlclient-mysqlhelper-executereader-overloads::  ExecuteReader Method
* connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads::  ExecuteScalar Method
* connector-net-ref-mysqlclient-mysqlhelper-updatedataset::  `MySqlHelper.UpdateDataSet' Method

*Note MySqlHelper overview: connector-net-ref-mysqlclient-mysqlhelper.

*Public Static (Shared) Methods*

*Note ExecuteDataRow:                Executes a single SQL statement and
connector-net-ref-mysqlclient-mysqlhelper-executedatarow.returns the first row of the
                                     resultset. A new MySqlConnection
                                     object is created, opened, and
                                     closed during this method.
*Note ExecuteDataset:                Overloaded. Executes a single SQL
connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads.statement and returns the resultset
                                     in a DataSet. A new MySqlConnection
                                     object is created, opened, and
                                     closed during this method.
*Note ExecuteNonQuery:               Overloaded. Executes a single
connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overloads.command against a MySQL database.
                                     The *Note MySqlConnection:
                                     connector-net-ref-mysqlclient-mysqlconnection.
                                     is assumed to be open when the
                                     method is called and remains open
                                     after the method completes.
*Note ExecuteReader:                 Overloaded. Executes a single
connector-net-ref-mysqlclient-mysqlhelper-executereader-overloads.command against a MySQL database.
*Note ExecuteScalar:                 Overloaded. Execute a single
connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads.command against a MySQL database.
*Note UpdateDataSet:                 Updates the given table with data
connector-net-ref-mysqlclient-mysqlhelper-updatedataset.from the given DataSet

*Public Instance Methods*

Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
ToString(inherited from Object)      Returns a Stringthat represents the
                                     current Object.

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executedatarow,  Next: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads,  Prev: connector-net-ref-mysqlclient-mysqlhelpermembers,  Up: connector-net-ref-mysqlclient-mysqlhelpermembers

30.2.4.201 `MySqlHelper.ExecuteDataRow' Method
..............................................

Executes a single SQL statement and returns the first row of the
resultset. A new MySqlConnection object is created, opened, and closed
during this method.

*Syntax: Visual Basic*

     Public Shared Function ExecuteDataRow( _
        ByVal connectionString As String, _
        ByVal commandText As String, _
        ParamArray parms As MySqlParameter() _
     ) As DataRow

*Syntax: C#*

     public static DataRow ExecuteDataRow(
     stringconnectionString,
     stringcommandText,
        params MySqlParameter[]parms
     );

*Parameters*

   * `connectionString': Settings to be used for the connection

   * `commandText': Command to execute

   * `parms': Parameters to use for the command

*Return Value*

DataRow containing the first row of the resultset

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads,  Next: connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overloads,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executedatarow,  Up: connector-net-ref-mysqlclient-mysqlhelpermembers

30.2.4.202 ExecuteDataset Method
................................

* Menu:

* connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-3::  `MySqlHelper.ExecuteDataset' Method
* connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-4::  `MySqlHelper.ExecuteDataset' Method
* connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-1::  `MySqlHelper.ExecuteDataset' Method
* connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-2::  `MySqlHelper.ExecuteDataset' Method

Executes a single SQL statement and returns the resultset in a DataSet.
The state of the *Note MySqlConnection:
connector-net-ref-mysqlclient-mysqlconnection.  object remains
unchanged after execution of this method.

*Overload List*

Executes a single SQL statement and returns the resultset in a DataSet.
The state of the *Note MySqlConnection:
connector-net-ref-mysqlclient-mysqlconnection.  object remains
unchanged after execution of this method.

   * *Note public static DataSet ExecuteDataset(MySqlConnection:
     (string);)connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-3.

Executes a single SQL statement and returns the resultset in a DataSet.
The state of the *Note MySqlConnection:
connector-net-ref-mysqlclient-mysqlconnection.  object remains
unchanged after execution of this method.

   * *Note public static DataSet ExecuteDataset(MySqlConnection:
     (string)connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-4.

Executes a single SQL statement and returns the resultset in a DataSet.
A new MySqlConnection object is created, opened, and closed during this
method.

   * *Note public static DataSet ExecuteDataset(string:
     (string);)connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-1.

Executes a single SQL statement and returns the resultset in a DataSet.
A new MySqlConnection object is created, opened, and closed during this
method.

   * *Note public static DataSet ExecuteDataset(string:
     (string)connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-2.

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-3,  Next: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-4,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads,  Up: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads

30.2.4.203 `MySqlHelper.ExecuteDataset' Method
..............................................

Executes a single SQL statement and returns the resultset in a DataSet.
The state of the *Note MySqlConnection:
connector-net-ref-mysqlclient-mysqlconnection.  object remains
unchanged after execution of this method.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteDataset( _
        ByVal connection As MySqlConnection, _
        ByVal commandText As String _
     ) As DataSet

*Syntax: C#*

     public static DataSet ExecuteDataset(
     MySqlConnectionconnection,
     stringcommandText
     );

*Parameters*

   * `connection': *Note MySqlConnection:
     connector-net-ref-mysqlclient-mysqlconnection.  object to use

   * `commandText': Command to execute

*Return Value*

DataSetcontaining the resultset

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteDataset Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-4,  Next: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-1,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-3,  Up: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads

30.2.4.204 `MySqlHelper.ExecuteDataset' Method
..............................................

Executes a single SQL statement and returns the resultset in a DataSet.
The state of the *Note MySqlConnection:
connector-net-ref-mysqlclient-mysqlconnection.  object remains
unchanged after execution of this method.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteDataset( _
        ByVal connection As MySqlConnection, _
        ByVal commandText As String, _
        ParamArray commandParameters As MySqlParameter() _
     ) As DataSet

*Syntax: C#*

     public static DataSet ExecuteDataset(
     MySqlConnectionconnection,
     stringcommandText,
        params MySqlParameter[]commandParameters
     );

*Parameters*

   * `connection': *Note MySqlConnection:
     connector-net-ref-mysqlclient-mysqlconnection.  object to use

   * `commandText': Command to execute

   * `commandParameters': Parameters to use for the command

*Return Value*

DataSetcontaining the resultset

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteDataset Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-1,  Next: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-4,  Up: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads

30.2.4.205 `MySqlHelper.ExecuteDataset' Method
..............................................

Executes a single SQL statement and returns the resultset in a DataSet.
A new MySqlConnection object is created, opened, and closed during this
method.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteDataset( _
        ByVal connectionString As String, _
        ByVal commandText As String _
     ) As DataSet

*Syntax: C#*

     public static DataSet ExecuteDataset(
     stringconnectionString,
     stringcommandText
     );

*Parameters*

   * `connectionString': Settings to be used for the connection

   * `commandText': Command to execute

*Return Value*

DataSetcontaining the resultset

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteDataset Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-1,  Up: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads

30.2.4.206 `MySqlHelper.ExecuteDataset' Method
..............................................

Executes a single SQL statement and returns the resultset in a DataSet.
A new MySqlConnection object is created, opened, and closed during this
method.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteDataset( _
        ByVal connectionString As String, _
        ByVal commandText As String, _
        ParamArray commandParameters As MySqlParameter() _
     ) As DataSet

*Syntax: C#*

     public static DataSet ExecuteDataset(
     stringconnectionString,
     stringcommandText,
        params MySqlParameter[]commandParameters
     );

*Parameters*

   * `connectionString': Settings to be used for the connection

   * `commandText': Command to execute

   * `commandParameters': Parameters to use for the command

*Return Value*

DataSetcontaining the resultset

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteDataset Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overloads,  Next: connector-net-ref-mysqlclient-mysqlhelper-executereader-overloads,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads,  Up: connector-net-ref-mysqlclient-mysqlhelpermembers

30.2.4.207 ExecuteNonQuery Method
.................................

* Menu:

* connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overload-1::  `MySqlHelper.ExecuteNonQuery' Method
* connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overload-2::  `MySqlHelper.ExecuteNonQuery' Method

Executes a single command against a MySQL database. The *Note
MySqlConnection: connector-net-ref-mysqlclient-mysqlconnection.  is
assumed to be open when the method is called and remains open after the
method completes.

*Overload List*

Executes a single command against a MySQL database. The *Note
MySqlConnection: connector-net-ref-mysqlclient-mysqlconnection.  is
assumed to be open when the method is called and remains open after the
method completes.

   * *Note public static int ExecuteNonQuery(MySqlConnection:
     (string)connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overload-1.

Executes a single command against a MySQL database. A new *Note
MySqlConnection: connector-net-ref-mysqlclient-mysqlconnection.  is
created using the *Note ConnectionString:
connector-net-ref-mysqlclient-mysqlconnection-connectionstring.  given.

   * *Note public static int ExecuteNonQuery(string:
     (string)connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overload-2.

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overload-1,  Next: connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overloads,  Up: connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overloads

30.2.4.208 `MySqlHelper.ExecuteNonQuery' Method
...............................................

Executes a single command against a MySQL database. The *Note
MySqlConnection: connector-net-ref-mysqlclient-mysqlconnection.  is
assumed to be open when the method is called and remains open after the
method completes.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteNonQuery( _
        ByVal connection As MySqlConnection, _
        ByVal commandText As String, _
        ParamArray commandParameters As MySqlParameter() _
     ) As Integer

*Syntax: C#*

     public static int ExecuteNonQuery(
     MySqlConnectionconnection,
     stringcommandText,
        params MySqlParameter[]commandParameters
     );

*Parameters*

   * `connection': *Note MySqlConnection:
     connector-net-ref-mysqlclient-mysqlconnection.  object to use

   * `commandText': SQL statement to be executed

   * `commandParameters': Array of *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter.  objects to use with
     the command.

*Return Value*

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteNonQuery Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overload-1,  Up: connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overloads

30.2.4.209 `MySqlHelper.ExecuteNonQuery' Method
...............................................

Executes a single command against a MySQL database. A new *Note
MySqlConnection: connector-net-ref-mysqlclient-mysqlconnection.  is
created using the *Note ConnectionString:
connector-net-ref-mysqlclient-mysqlconnection-connectionstring.  given.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteNonQuery( _
        ByVal connectionString As String, _
        ByVal commandText As String, _
        ParamArray parms As MySqlParameter() _
     ) As Integer

*Syntax: C#*

     public static int ExecuteNonQuery(
     stringconnectionString,
     stringcommandText,
        params MySqlParameter[]parms
     );

*Parameters*

   * `connectionString': *Note ConnectionString:
     connector-net-ref-mysqlclient-mysqlconnection-connectionstring.
     to use

   * `commandText': SQL statement to be executed

   * `parms': Array of *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter.  objects to use with
     the command.

*Return Value*

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteNonQuery Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executereader-overloads,  Next: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overloads,  Up: connector-net-ref-mysqlclient-mysqlhelpermembers

30.2.4.210 ExecuteReader Method
...............................

* Menu:

* connector-net-ref-mysqlclient-mysqlhelper-executereader-overload-1::  `MySqlHelper.ExecuteReader' Method
* connector-net-ref-mysqlclient-mysqlhelper-executereader-overload-2::  `MySqlHelper.ExecuteReader' Method

Executes a single command against a MySQL database.

*Overload List*

Executes a single command against a MySQL database.

   * *Note public static MySqlDataReader ExecuteReader(string:
     (string);)connector-net-ref-mysqlclient-mysqlhelper-executereader-overload-1.

Executes a single command against a MySQL database.

   * *Note public static MySqlDataReader ExecuteReader(string:
     (string)connector-net-ref-mysqlclient-mysqlhelper-executereader-overload-2.

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executereader-overload-1,  Next: connector-net-ref-mysqlclient-mysqlhelper-executereader-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executereader-overloads,  Up: connector-net-ref-mysqlclient-mysqlhelper-executereader-overloads

30.2.4.211 `MySqlHelper.ExecuteReader' Method
.............................................

Executes a single command against a MySQL database.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteReader( _
        ByVal connectionString As String, _
        ByVal commandText As String _
     ) As MySqlDataReader

*Syntax: C#*

     public static MySqlDataReader ExecuteReader(
     stringconnectionString,
     stringcommandText
     );

*Parameters*

   * `connectionString': Settings to use for this command

   * `commandText': Command text to use

*Return Value*

*Note MySqlDataReader: connector-net-ref-mysqlclient-mysqldatareader.
object ready to read the results of the command

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteReader Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executereader-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executereader-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executereader-overload-1,  Up: connector-net-ref-mysqlclient-mysqlhelper-executereader-overloads

30.2.4.212 `MySqlHelper.ExecuteReader' Method
.............................................

Executes a single command against a MySQL database.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteReader( _
        ByVal connectionString As String, _
        ByVal commandText As String, _
        ParamArray commandParameters As MySqlParameter() _
     ) As MySqlDataReader

*Syntax: C#*

     public static MySqlDataReader ExecuteReader(
     stringconnectionString,
     stringcommandText,
        params MySqlParameter[]commandParameters
     );

*Parameters*

   * `connectionString': Settings to use for this command

   * `commandText': Command text to use

   * `commandParameters': Array of *Note MySqlParameter:
     connector-net-ref-mysqlclient-mysqlparameter.  objects to use with
     the command

*Return Value*

*Note MySqlDataReader: connector-net-ref-mysqlclient-mysqldatareader.
object ready to read the results of the command

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteReader Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executereader-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads,  Next: connector-net-ref-mysqlclient-mysqlhelper-updatedataset,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executereader-overloads,  Up: connector-net-ref-mysqlclient-mysqlhelpermembers

30.2.4.213 ExecuteScalar Method
...............................

* Menu:

* connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-3::  `MySqlHelper.ExecuteScalar' Method
* connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-4::  `MySqlHelper.ExecuteScalar' Method
* connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-1::  `MySqlHelper.ExecuteScalar' Method
* connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-2::  `MySqlHelper.ExecuteScalar' Method

Execute a single command against a MySQL database.

*Overload List*

Execute a single command against a MySQL database.

   * *Note public static object ExecuteScalar(MySqlConnection:
     (string);)connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-3.

Execute a single command against a MySQL database.

   * *Note public static object ExecuteScalar(MySqlConnection:
     (string)connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-4.

Execute a single command against a MySQL database.

   * *Note public static object ExecuteScalar(string:
     (string);)connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-1.

Execute a single command against a MySQL database.

   * *Note public static object ExecuteScalar(string:
     (string)connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-2.

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-3,  Next: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-4,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads,  Up: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads

30.2.4.214 `MySqlHelper.ExecuteScalar' Method
.............................................

Execute a single command against a MySQL database.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteScalar( _
        ByVal connection As MySqlConnection, _
        ByVal commandText As String _
     ) As Object

*Syntax: C#*

     public static object ExecuteScalar(
     MySqlConnectionconnection,
     stringcommandText
     );

*Parameters*

   * `connection': *Note MySqlConnection:
     connector-net-ref-mysqlclient-mysqlconnection.  object to use

   * `commandText': Command text to use for the command

*Return Value*

The first column of the first row in the result set, or a null
reference if the result set is empty.

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteScalar Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-4,  Next: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-1,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-3,  Up: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads

30.2.4.215 `MySqlHelper.ExecuteScalar' Method
.............................................

Execute a single command against a MySQL database.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteScalar( _
        ByVal connection As MySqlConnection, _
        ByVal commandText As String, _
        ParamArray commandParameters As MySqlParameter() _
     ) As Object

*Syntax: C#*

     public static object ExecuteScalar(
     MySqlConnectionconnection,
     stringcommandText,
        params MySqlParameter[]commandParameters
     );

*Parameters*

   * `connection': *Note MySqlConnection:
     connector-net-ref-mysqlclient-mysqlconnection.  object to use

   * `commandText': Command text to use for the command

   * `commandParameters': Parameters to use for the command

*Return Value*

The first column of the first row in the result set, or a null
reference if the result set is empty.

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteScalar Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-1,  Next: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-4,  Up: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads

30.2.4.216 `MySqlHelper.ExecuteScalar' Method
.............................................

Execute a single command against a MySQL database.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteScalar( _
        ByVal connectionString As String, _
        ByVal commandText As String _
     ) As Object

*Syntax: C#*

     public static object ExecuteScalar(
     stringconnectionString,
     stringcommandText
     );

*Parameters*

   * `connectionString': Settings to use for the update

   * `commandText': Command text to use for the update

*Return Value*

The first column of the first row in the result set, or a null
reference if the result set is empty.

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteScalar Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-2,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-1,  Up: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads

30.2.4.217 `MySqlHelper.ExecuteScalar' Method
.............................................

Execute a single command against a MySQL database.

*Syntax: Visual Basic*

     Overloads Public Shared Function ExecuteScalar( _
        ByVal connectionString As String, _
        ByVal commandText As String, _
        ParamArray commandParameters As MySqlParameter() _
     ) As Object

*Syntax: C#*

     public static object ExecuteScalar(
     stringconnectionString,
     stringcommandText,
        params MySqlParameter[]commandParameters
     );

*Parameters*

   * `connectionString': Settings to use for the command

   * `commandText': Command text to use for the command

   * `commandParameters': Parameters to use for the command

*Return Value*

The first column of the first row in the result set, or a null
reference if the result set is empty.

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient ,
*Note MySqlHelper.ExecuteScalar Overload List:
connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlhelper-updatedataset,  Prev: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads,  Up: connector-net-ref-mysqlclient-mysqlhelpermembers

30.2.4.218 `MySqlHelper.UpdateDataSet' Method
.............................................

Updates the given table with data from the given DataSet

*Syntax: Visual Basic*

     Public Shared Sub UpdateDataSet( _
        ByVal connectionString As String, _
        ByVal commandText As String, _
        ByVal ds As DataSet, _
        ByVal tablename As String _
     )

*Syntax: C#*

     public static void UpdateDataSet(
     stringconnectionString,
     stringcommandText,
     DataSetds,
     stringtablename
     );

*Parameters*

   * `connectionString': Settings to use for the update

   * `commandText': Command text to use for the update

   * `ds': DataSetcontaining the new data to use in the update

   * `tablename': Tablename in the data set to update

*See Also*

*Note MySqlHelper Class: connector-net-ref-mysqlclient-mysqlhelper ,
*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-mysqlclient-mysqlerrorcode,  Prev: connector-net-ref-mysqlclient-mysqlhelper,  Up: connector-net-ref-mysqlclient

30.2.4.219 `MySqlErrorCode' Enumeration
.......................................

*Syntax: Visual Basic*

     Public Enum MySqlErrorCode

*Syntax: C#*

     public enum MySqlErrorCode

*Members*

*Member Name*                        *Description*
PacketTooLarge                       
PasswordNotAllowed                   
DuplicateKeyEntry                    
HostNotPrivileged                    
PasswordNoMatch                      
AnonymousUser                        
DuplicateKey                         
KeyNotFound                          
DuplicateKeyName                     

*Requirements*

Namespace: *Note MySql.Data.MySqlClient: connector-net-ref-mysqlclient.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySql.Data.MySqlClient Namespace: connector-net-ref-mysqlclient.


File: manual.info,  Node: connector-net-ref-types,  Prev: connector-net-ref-mysqlclient,  Up: connector-net-ref

30.2.4.220 `MySql.Data.Types'
.............................

* Menu:

* connector-net-ref-typeshierarchy::  `MySql.Data.TypesHierarchy'
* connector-net-ref-types-mysqlconversionexception::  `MySqlConversionException' Class
* connector-net-ref-types-mysqldatetime::  `MySqlDateTime' Class

*Note Namespace hierarchy: connector-net-ref-typeshierarchy.

*Classes*

*Class*                              *Description*
*Note MySqlConversionException:      Summary description for
connector-net-ref-types-mysqlconversionexception.MySqlConversionException.
*Note MySqlDateTime:                 Summary description for
connector-net-ref-types-mysqldatetime.MySqlDateTime.
*Note MySqlValue:                    
connector-net-ref-types-mysqlvalue.  


File: manual.info,  Node: connector-net-ref-typeshierarchy,  Next: connector-net-ref-types-mysqlconversionexception,  Prev: connector-net-ref-types,  Up: connector-net-ref-types

30.2.4.221 `MySql.Data.TypesHierarchy'
......................................

*See Also*

*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlconversionexception,  Next: connector-net-ref-types-mysqldatetime,  Prev: connector-net-ref-typeshierarchy,  Up: connector-net-ref-types

30.2.4.222 `MySqlConversionException' Class
...........................................

* Menu:

* connector-net-ref-types-mysqlconversionexceptionmembers::  `MySqlConversionException' Members

Summary description for MySqlConversionException.

For a list of all members of this type, see *Note
MySqlConversionException Members:
connector-net-ref-types-mysqlconversionexceptionmembers .

*Syntax: Visual Basic*

     Public Class MySqlConversionException_
       Inherits ApplicationException

*Syntax: C#*

     public class MySqlConversionException : ApplicationException

*Thread Safety*

Public static (Sharedin Visual Basic) members of this type are safe for
multithreaded operations. Instance members are notguaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.Types: connector-net-ref-types.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlConversionException Members:
connector-net-ref-types-mysqlconversionexceptionmembers , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlconversionexceptionmembers,  Prev: connector-net-ref-types-mysqlconversionexception,  Up: connector-net-ref-types-mysqlconversionexception

30.2.4.223 `MySqlConversionException' Members
.............................................

* Menu:

* connector-net-ref-types-mysqlconversionexceptionconstructor::  `MySqlConversionException' Constructor

*Note MySqlConversionException overview:
connector-net-ref-types-mysqlconversionexception.

*Public Instance Constructors*

*Note MySqlConversionException       Ctor
Constructor:                         
connector-net-ref-types-mysqlconversionexceptionconstructor.

*Public Instance Properties*

Data(inherited from Exception)       Gets a collection of key/value
                                     pairs that provide additional,
                                     user-defined information about the
                                     exception.
HelpLink(inherited from Exception)   Gets or sets a link to the help
                                     file associated with this exception.
InnerException(inherited from        Gets the Exceptioninstance that
Exception)                           caused the current exception.
Message(inherited from Exception)    Gets a message that describes the
                                     current exception.
Source(inherited from Exception)     Gets or sets the name of the
                                     application or the object that
                                     causes the error.
StackTrace(inherited from Exception) Gets a string representation of the
                                     frames on the call stack at the time
                                     the current exception was thrown.
TargetSite(inherited from Exception) Gets the method that throws the
                                     current exception.

*Public Instance Methods*

Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetBaseException(inherited from      When overridden in a derived class,
Exception)                           returns the Exceptionthat is the
                                     root cause of one or more
                                     subsequent exceptions.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetObjectData(inherited from         When overridden in a derived class,
Exception)                           sets the SerializationInfowith
                                     information about the exception.
GetType(inherited from Exception)    Gets the runtime type of the
                                     current instance.
ToString(inherited from Exception)   Creates and returns a string
                                     representation of the current
                                     exception.

*Protected Instance Properties*

HResult(inherited from Exception)    Gets or sets HRESULT, a coded
                                     numerical value that is assigned to
                                     a specific exception.

*Protected Instance Methods*

Finalize(inherited from Object)      Allows an Objectto attempt to free
                                     resources and perform other cleanup
                                     operations before the Objectis
                                     reclaimed by garbage collection.
MemberwiseClone(inherited from       Creates a shallow copy of the
Object)                              current Object.

*See Also*

*Note MySqlConversionException Class:
connector-net-ref-types-mysqlconversionexception , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlconversionexceptionconstructor,  Prev: connector-net-ref-types-mysqlconversionexceptionmembers,  Up: connector-net-ref-types-mysqlconversionexceptionmembers

30.2.4.224 `MySqlConversionException' Constructor
.................................................

*Syntax: Visual Basic*

     Public Sub New( _
        ByVal msg As String _
     )

*Syntax: C#*

     public MySqlConversionException(
     stringmsg
     );

*See Also*

*Note MySqlConversionException Class:
connector-net-ref-types-mysqlconversionexception , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetime,  Prev: connector-net-ref-types-mysqlconversionexception,  Up: connector-net-ref-types

30.2.4.225 `MySqlDateTime' Class
................................

* Menu:

* connector-net-ref-types-mysqldatetimemembers::  `MySqlDateTime' Members

Summary description for MySqlDateTime.

For a list of all members of this type, see *Note MySqlDateTime
Members: connector-net-ref-types-mysqldatetimemembers .

*Syntax: Visual Basic*

     Public Class MySqlDateTime_
       Inherits MySqlValue_
       Implements IConvertible, IComparable

*Syntax: C#*

     public class MySqlDateTime : MySqlValue, IConvertible, IComparable

*Thread Safety*

Public static (Shared in Visual Basic) members of this type are safe
for multithreaded operations. Instance members are not guaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.Types: connector-net-ref-types.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlDateTime Members:
connector-net-ref-types-mysqldatetimemembers , *Note MySql.Data.Types
Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetimemembers,  Prev: connector-net-ref-types-mysqldatetime,  Up: connector-net-ref-types-mysqldatetime

30.2.4.226 `MySqlDateTime' Members
..................................

* Menu:

* connector-net-ref-types-mysqldatetime-op-explicit::  `MySqlDateTime' Explicit `MySqlDateTime' to `DateTime' Conversion
* connector-net-ref-types-mysqldatetime-day::  Day Property
* connector-net-ref-types-mysqldatetime-hour::  Hour Property
* connector-net-ref-types-mysqlvalue-isnull::  IsNull Property
* connector-net-ref-types-mysqldatetime-isvaliddatetime::  IsValidDateTime Property
* connector-net-ref-types-mysqldatetime-minute::  Minute Property
* connector-net-ref-types-mysqldatetime-month::  Month Property
* connector-net-ref-types-mysqldatetime-second::  Second Property
* connector-net-ref-types-mysqldatetime-year::  Year Property
* connector-net-ref-types-mysqldatetime-getdatetime::  `MySqlDateTime.GetDateTime' Method
* connector-net-ref-types-mysqldatetime-tostring::  `MySqlDateTime.ToString' Method

*Note MySqlDateTime overview: connector-net-ref-types-mysqldatetime.

*Public Static (Shared) Type Conversions*

*Note Explicit MySqlDateTime to      
DateTime Conversion:                 
connector-net-ref-types-mysqldatetime-op-explicit.

*Public Instance Properties*

*Note Day:                           Returns the day portion of this
connector-net-ref-types-mysqldatetime-day.datetime
*Note Hour:                          Returns the hour portion of this
connector-net-ref-types-mysqldatetime-hour.datetime
*Note IsNull:                        
connector-net-ref-types-mysqlvalue-isnull.
(inherited from MySqlValue)          
*Note IsValidDateTime:               Indicates if this object contains a
connector-net-ref-types-mysqldatetime-isvaliddatetime.value that can be represented as a
                                     DateTime
*Note Minute:                        Returns the minute portion of this
connector-net-ref-types-mysqldatetime-minute.datetime
*Note Month:                         Returns the month portion of this
connector-net-ref-types-mysqldatetime-month.datetime
*Note Second:                        Returns the second portion of this
connector-net-ref-types-mysqldatetime-second.datetime
*Note ValueAsObject:                 Returns the value of this field as
connector-net-ref-types-mysqlvalue-valueasobject.an object
(inherited from MySqlValue)          
*Note Year:                          Returns the year portion of this
connector-net-ref-types-mysqldatetime-year.datetime

*Public Instance Methods*

Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
*Note GetDateTime:                   Returns this value as a DateTime
connector-net-ref-types-mysqldatetime-getdatetime.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
*Note ToString:                      Returns a MySQL specific string
connector-net-ref-types-mysqldatetime-tostring.representation of this value

*Protected Instance Fields*

*Note classType:                     The system type represented by this
connector-net-ref-types-mysqlvalue-classtype.value
(inherited from MySqlValue)          
*Note dbType:                        The generic dbtype of this value
connector-net-ref-types-mysqlvalue-dbtype.
(inherited from MySqlValue)          
*Note isNull:                        Is this value null
connector-net-ref-types-mysqlvalue-isnull.
(inherited from MySqlValue)          
*Note mySqlDbType:                   The specific MySQL db type
connector-net-ref-types-mysqlvalue-mysqldbtype.
(inherited from MySqlValue)          
*Note mySqlTypeName:                 The MySQL specific typename of this
connector-net-ref-types-mysqlvalue-mysqltypename.value
(inherited from MySqlValue)          
*Note objectValue:                   
connector-net-ref-types-mysqlvalue-objectvalue.
(inherited from MySqlValue)          

*Protected Instance Methods*

Finalize(inherited from Object)      Allows an Objectto attempt to free
                                     resources and perform other cleanup
                                     operations before the Objectis
                                     reclaimed by garbage collection.
MemberwiseClone(inherited from       Creates a shallow copy of the
Object)                              current Object.

*See Also*

*Note MySqlDateTime Class: connector-net-ref-types-mysqldatetime ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetime-op-explicit,  Next: connector-net-ref-types-mysqldatetime-day,  Prev: connector-net-ref-types-mysqldatetimemembers,  Up: connector-net-ref-types-mysqldatetimemembers

30.2.4.227 `MySqlDateTime' Explicit `MySqlDateTime' to `DateTime' Conversion
............................................................................

*Syntax: Visual Basic*

     MySqlDateTime.op_Explicit(val)

*Syntax: C#*

     public static explicit operator DateTime(
     MySqlDateTimeval
     );

*Parameters*

   * `val':

*Return Value*

*See Also*

*Note MySqlDateTime Class: connector-net-ref-types-mysqldatetime ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetime-day,  Next: connector-net-ref-types-mysqldatetime-hour,  Prev: connector-net-ref-types-mysqldatetime-op-explicit,  Up: connector-net-ref-types-mysqldatetimemembers

30.2.4.228 Day Property
.......................

Returns the day portion of this datetime

*Syntax: Visual Basic*

     Public Property Day As Integer

*Syntax: C#*

     public int Day {get; set;}

*See Also*

*Note MySqlDateTime Class: connector-net-ref-types-mysqldatetime ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetime-hour,  Next: connector-net-ref-types-mysqlvalue-isnull,  Prev: connector-net-ref-types-mysqldatetime-day,  Up: connector-net-ref-types-mysqldatetimemembers

30.2.4.229 Hour Property
........................

Returns the hour portion of this datetime

*Syntax: Visual Basic*

     Public Property Hour As Integer

*Syntax: C#*

     public int Hour {get; set;}

*See Also*

*Note MySqlDateTime Class: connector-net-ref-types-mysqldatetime ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvalue-isnull,  Next: connector-net-ref-types-mysqldatetime-isvaliddatetime,  Prev: connector-net-ref-types-mysqldatetime-hour,  Up: connector-net-ref-types-mysqldatetimemembers

30.2.4.230 IsNull Property
..........................

* Menu:

* connector-net-ref-types-mysqlvalue::  `MySqlValue' Class

*Syntax: Visual Basic*

     Public Property IsNull As Boolean

*Syntax: C#*

     public bool IsNull {get; set;}

*See Also*

*Note MySqlValue Class: connector-net-ref-types-mysqlvalue , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvalue,  Prev: connector-net-ref-types-mysqlvalue-isnull,  Up: connector-net-ref-types-mysqlvalue-isnull

30.2.4.231 `MySqlValue' Class
.............................

* Menu:

* connector-net-ref-types-mysqlvaluemembers::  `MySqlValue' Members

For a list of all members of this type, see *Note MySqlValue Members:
connector-net-ref-types-mysqlvaluemembers .

*Syntax: Visual Basic*

     MustInherit Public Class MySqlValue

*Syntax: C#*

     public abstract class MySqlValue

*Thread Safety*

Public static (Shared in Visual Basic) members of this type are safe
for multithreaded operations. Instance members are not guaranteed to be
thread-safe.

*Requirements*

Namespace: *Note MySql.Data.Types: connector-net-ref-types.

Assembly: MySql.Data (in MySql.Data.dll)

*See Also*

*Note MySqlValue Members: connector-net-ref-types-mysqlvaluemembers ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvaluemembers,  Prev: connector-net-ref-types-mysqlvalue,  Up: connector-net-ref-types-mysqlvalue

30.2.4.232 `MySqlValue' Members
...............................

* Menu:

* connector-net-ref-types-mysqlvalue-numberformat::  `MySqlValue.numberFormat' Field
* connector-net-ref-types-mysqlvalueconstructor::  `MySqlValue' Constructor
* connector-net-ref-types-mysqlvalue-valueasobject::  ValueAsObject Property
* connector-net-ref-types-mysqlvalue-tostring::  `MySqlValue.ToString' Method
* connector-net-ref-types-mysqlvalue-classtype::  `MySqlValue.classType' Field
* connector-net-ref-types-mysqlvalue-dbtype::  `MySqlValue.dbType' Field
* connector-net-ref-types-mysqlvalue-mysqldbtype::  `MySqlValue.mySqlDbType' Field
* connector-net-ref-types-mysqlvalue-mysqltypename::  `MySqlValue.mySqlTypeName' Field
* connector-net-ref-types-mysqlvalue-objectvalue::  `MySqlValue.objectValue' Field

*Note MySqlValue overview: connector-net-ref-types-mysqlvalue.

*Protected Static (Shared) Fields*

*Note numberFormat:                  
connector-net-ref-types-mysqlvalue-numberformat.

*Public Instance Constructors*

*Note MySqlValue Constructor:        Initializes a new instance of the
connector-net-ref-types-mysqlvalueconstructor.*Note MySqlValue:
                                     connector-net-ref-types-mysqlvalue.
                                     class.

*Public Instance Properties*

*Note IsNull:                        
connector-net-ref-types-mysqlvalue-isnull.
*Note ValueAsObject:                 Returns the value of this field as
connector-net-ref-types-mysqlvalue-valueasobject.an object

*Public Instance Methods*

Equals(inherited from Object)        Determines whether the specified
                                     Objectis equal to the current
                                     Object.
GetHashCode(inherited from Object)   Serves as a hash function for a
                                     particular type. GetHashCodeis
                                     suitable for use in hashing
                                     algorithms and data structures like
                                     a hash table.
GetType(inherited from Object)       Gets the Typeof the current
                                     instance.
*Note ToString:                      Returns a string representation of
connector-net-ref-types-mysqlvalue-tostring.this value

*Protected Instance Fields*

*Note classType:                     The system type represented by this
connector-net-ref-types-mysqlvalue-classtype.value
*Note dbType:                        The generic dbtype of this value
connector-net-ref-types-mysqlvalue-dbtype.
*Note isNull:                        Is this value null
connector-net-ref-types-mysqlvalue-isnull.
*Note mySqlDbType:                   The specific MySQL db type
connector-net-ref-types-mysqlvalue-mysqldbtype.
*Note mySqlTypeName:                 The MySQL specific typename of this
connector-net-ref-types-mysqlvalue-mysqltypename.value
*Note objectValue:                   
connector-net-ref-types-mysqlvalue-objectvalue.

*Protected Instance Methods*

Finalize(inherited from Object)      Allows an Objectto attempt to free
                                     resources and perform other cleanup
                                     operations before the Objectis
                                     reclaimed by garbage collection.
MemberwiseClone(inherited from       Creates a shallow copy of the
Object)                              current Object.

*See Also*

*Note MySqlValue Class: connector-net-ref-types-mysqlvalue , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvalue-numberformat,  Next: connector-net-ref-types-mysqlvalueconstructor,  Prev: connector-net-ref-types-mysqlvaluemembers,  Up: connector-net-ref-types-mysqlvaluemembers

30.2.4.233 `MySqlValue.numberFormat' Field
..........................................

*Syntax: Visual Basic*

     Protected Shared numberFormat As NumberFormatInfo

*Syntax: C#*

     protected static NumberFormatInfo numberFormat;

*See Also*

*Note MySqlValue Class: connector-net-ref-types-mysqlvalue , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvalueconstructor,  Next: connector-net-ref-types-mysqlvalue-valueasobject,  Prev: connector-net-ref-types-mysqlvalue-numberformat,  Up: connector-net-ref-types-mysqlvaluemembers

30.2.4.234 `MySqlValue' Constructor
...................................

Initializes a new instance of the *Note MySqlValue:
connector-net-ref-types-mysqlvalue.  class.

*Syntax: Visual Basic*

     Public Sub New()

*Syntax: C#*

     public MySqlValue();

*See Also*

*Note MySqlValue Class: connector-net-ref-types-mysqlvalue , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvalue-valueasobject,  Next: connector-net-ref-types-mysqlvalue-tostring,  Prev: connector-net-ref-types-mysqlvalueconstructor,  Up: connector-net-ref-types-mysqlvaluemembers

30.2.4.235 ValueAsObject Property
.................................

Returns the value of this field as an object

*Syntax: Visual Basic*

     Public ReadOnly Property ValueAsObject As Object

*Syntax: C#*

     public object ValueAsObject {get;}

*See Also*

*Note MySqlValue Class: connector-net-ref-types-mysqlvalue , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvalue-tostring,  Next: connector-net-ref-types-mysqlvalue-classtype,  Prev: connector-net-ref-types-mysqlvalue-valueasobject,  Up: connector-net-ref-types-mysqlvaluemembers

30.2.4.236 `MySqlValue.ToString' Method
.......................................

Returns a string representation of this value

*Syntax: Visual Basic*

     Overrides Public Function ToString() As String

*Syntax: C#*

     public override string ToString();

*See Also*

*Note MySqlValue Class: connector-net-ref-types-mysqlvalue , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvalue-classtype,  Next: connector-net-ref-types-mysqlvalue-dbtype,  Prev: connector-net-ref-types-mysqlvalue-tostring,  Up: connector-net-ref-types-mysqlvaluemembers

30.2.4.237 `MySqlValue.classType' Field
.......................................

The system type represented by this value

*Syntax: Visual Basic*

     Protected classType As Type

*Syntax: C#*

     protected Type classType;

*See Also*

*Note MySqlValue Class: connector-net-ref-types-mysqlvalue , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvalue-dbtype,  Next: connector-net-ref-types-mysqlvalue-mysqldbtype,  Prev: connector-net-ref-types-mysqlvalue-classtype,  Up: connector-net-ref-types-mysqlvaluemembers

30.2.4.238 `MySqlValue.dbType' Field
....................................

The generic dbtype of this value

*Syntax: Visual Basic*

     Protected dbType As DbType

*Syntax: C#*

     protected DbType dbType;

*See Also*

*Note MySqlValue Class: connector-net-ref-types-mysqlvalue , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvalue-mysqldbtype,  Next: connector-net-ref-types-mysqlvalue-mysqltypename,  Prev: connector-net-ref-types-mysqlvalue-dbtype,  Up: connector-net-ref-types-mysqlvaluemembers

30.2.4.239 `MySqlValue.mySqlDbType' Field
.........................................

The specific MySQL db type

*Syntax: Visual Basic*

     Protected mySqlDbType As MySqlDbType

*Syntax: C#*

     protected MySqlDbType mySqlDbType;

*See Also*

*Note MySqlValue Class: connector-net-ref-types-mysqlvalue , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvalue-mysqltypename,  Next: connector-net-ref-types-mysqlvalue-objectvalue,  Prev: connector-net-ref-types-mysqlvalue-mysqldbtype,  Up: connector-net-ref-types-mysqlvaluemembers

30.2.4.240 `MySqlValue.mySqlTypeName' Field
...........................................

The MySQL specific typename of this value

*Syntax: Visual Basic*

     Protected mySqlTypeName As String

*Syntax: C#*

     protected string mySqlTypeName;

*See Also*

*Note MySqlValue Class: connector-net-ref-types-mysqlvalue , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqlvalue-objectvalue,  Prev: connector-net-ref-types-mysqlvalue-mysqltypename,  Up: connector-net-ref-types-mysqlvaluemembers

30.2.4.241 `MySqlValue.objectValue' Field
.........................................

*Syntax: Visual Basic*

     Protected objectValue As Object

*Syntax: C#*

     protected object objectValue;

*See Also*

*Note MySqlValue Class: connector-net-ref-types-mysqlvalue , *Note
MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetime-isvaliddatetime,  Next: connector-net-ref-types-mysqldatetime-minute,  Prev: connector-net-ref-types-mysqlvalue-isnull,  Up: connector-net-ref-types-mysqldatetimemembers

30.2.4.242 IsValidDateTime Property
...................................

Indicates if this object contains a value that can be represented as a
DateTime

*Syntax: Visual Basic*

     Public ReadOnly Property IsValidDateTime As Boolean

*Syntax: C#*

     public bool IsValidDateTime {get;}

*See Also*

*Note MySqlDateTime Class: connector-net-ref-types-mysqldatetime ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetime-minute,  Next: connector-net-ref-types-mysqldatetime-month,  Prev: connector-net-ref-types-mysqldatetime-isvaliddatetime,  Up: connector-net-ref-types-mysqldatetimemembers

30.2.4.243 Minute Property
..........................

Returns the minute portion of this datetime

*Syntax: Visual Basic*

     Public Property Minute As Integer

*Syntax: C#*

     public int Minute {get; set;}

*See Also*

*Note MySqlDateTime Class: connector-net-ref-types-mysqldatetime ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetime-month,  Next: connector-net-ref-types-mysqldatetime-second,  Prev: connector-net-ref-types-mysqldatetime-minute,  Up: connector-net-ref-types-mysqldatetimemembers

30.2.4.244 Month Property
.........................

Returns the month portion of this datetime

*Syntax: Visual Basic*

     Public Property Month As Integer

*Syntax: C#*

     public int Month {get; set;}

*See Also*

*Note MySqlDateTime Class: connector-net-ref-types-mysqldatetime ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetime-second,  Next: connector-net-ref-types-mysqldatetime-year,  Prev: connector-net-ref-types-mysqldatetime-month,  Up: connector-net-ref-types-mysqldatetimemembers

30.2.4.245 Second Property
..........................

Returns the second portion of this datetime

*Syntax: Visual Basic*

     Public Property Second As Integer

*Syntax: C#*

     public int Second {get; set;}

*See Also*

*Note MySqlDateTime Class: connector-net-ref-types-mysqldatetime ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetime-year,  Next: connector-net-ref-types-mysqldatetime-getdatetime,  Prev: connector-net-ref-types-mysqldatetime-second,  Up: connector-net-ref-types-mysqldatetimemembers

30.2.4.246 Year Property
........................

Returns the year portion of this datetime

*Syntax: Visual Basic*

     Public Property Year As Integer

*Syntax: C#*

     public int Year {get; set;}

*See Also*

*Note MySqlDateTime Class: connector-net-ref-types-mysqldatetime ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetime-getdatetime,  Next: connector-net-ref-types-mysqldatetime-tostring,  Prev: connector-net-ref-types-mysqldatetime-year,  Up: connector-net-ref-types-mysqldatetimemembers

30.2.4.247 `MySqlDateTime.GetDateTime' Method
.............................................

Returns this value as a DateTime

*Syntax: Visual Basic*

     Public Function GetDateTime() As Date

*Syntax: C#*

     public DateTime GetDateTime();

*See Also*

*Note MySqlDateTime Class: connector-net-ref-types-mysqldatetime ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-ref-types-mysqldatetime-tostring,  Prev: connector-net-ref-types-mysqldatetime-getdatetime,  Up: connector-net-ref-types-mysqldatetimemembers

30.2.4.248 `MySqlDateTime.ToString' Method
..........................................

Returns a MySQL specific string representation of this value

*Syntax: Visual Basic*

     Overrides Public Function ToString() As String

*Syntax: C#*

     public override string ToString();

*See Also*

*Note MySqlDateTime Class: connector-net-ref-types-mysqldatetime ,
*Note MySql.Data.Types Namespace: connector-net-ref-types.


File: manual.info,  Node: connector-net-using,  Next: connect-net-support,  Prev: connector-net-ref,  Up: connector-net

30.2.5 Connector/NET Notes and Tips
-----------------------------------

* Menu:

* connector-net-using-connecting::  Connecting to MySQL Using Connector/NET
* connector-net-using-prepared::  Using the Connector/NET with Prepared Statements
* connector-net-using-stored::   Accessing Stored Procedures with Connector/NET
* connector-net-using-blob::     Handling BLOB Data With Connector/NET
* connector-net-using-crystal::  Using Connector/NET with Crystal Reports
* connector-net-using-datetime::  Handling Date and Time Information in Connector/NET
* connector-net-using-faq::      Frequently Asked Questions

In this section we will cover some of the more common use cases for
Connector/NET, including BLOB handling, date handling, and using
Connector/NET with common tools such as Crystal Reports.


File: manual.info,  Node: connector-net-using-connecting,  Next: connector-net-using-prepared,  Prev: connector-net-using,  Up: connector-net-using

30.2.5.1 Connecting to MySQL Using Connector/NET
................................................

* Menu:

* connector-net-using-connecting-introduction::  Introduction
* connector-net-using-connecting-connection-string::  Creating a Connection String
* connector-net-using-connecting-open::  Opening a Connection
* connector-net-using-connecting-errors::  Handling Connection Errors


File: manual.info,  Node: connector-net-using-connecting-introduction,  Next: connector-net-using-connecting-connection-string,  Prev: connector-net-using-connecting,  Up: connector-net-using-connecting

30.2.5.2 Introduction
.....................

All interaction between a .NET application and the MySQL server is
routed through a `MySqlConnection' object. Before your application can
interact with the server, a `MySqlConnection' object must be instanced,
configured, and opened.

Even when using the `MySqlHelper' class, a `MySqlConnection' object is
created by the helper class.

In this section, we will describe how to connect to MySQL using the
`MySqlConnection' object.


File: manual.info,  Node: connector-net-using-connecting-connection-string,  Next: connector-net-using-connecting-open,  Prev: connector-net-using-connecting-introduction,  Up: connector-net-using-connecting

30.2.5.3 Creating a Connection String
.....................................

The `MySqlConnection' object is configured using a connection string. A
connection string contains sever key/value pairs, separated by
semicolons. Each key/value pair is joined with an equals sign.

The following is a sample connection string:

         Server=127.0.0.1;Uid=root;Pwd=12345;Database=test;

In this example, the `MySqlConnection' object is configured to connect
to a MySQL server at `127.0.0.1', with a username of `root' and a
password of `12345'. The default database for all statements will be
the `test' database.

The following options are typically used (a full list of options is
available in the API documentation for *Note
connector-net-examples-mysqlconnection-connectionstring::):

   * `Server': The name or network address of the instance of MySQL to
     which to connect. The default is `localhost'. Aliases include
     `host', `Data Source', `DataSource', `Address', `Addr' and `Network
     Address'.

   * `Uid': The MySQL user account to use when connecting. Aliases
     include `User Id', `Username' and `User name'.

   * `Pwd': The password for the MySQL account being used. Alias
     `Password' can also be used.

   * `Database': The default database that all statements are applied
     to. Default is `mysql'. Alias `Initial Catalog' can also be used.

   * `Port': The port MySQL is using to listen for connections. Default
     is `3306'.  Specify `-1' for this value to use a named-pipe
     connection.


File: manual.info,  Node: connector-net-using-connecting-open,  Next: connector-net-using-connecting-errors,  Prev: connector-net-using-connecting-connection-string,  Up: connector-net-using-connecting

30.2.5.4 Opening a Connection
.............................

Once you have created a connection string it can be used to open a
connection to the MySQL server.

The following code is used to create a `MySqlConnection' object, assign
the connection string, and open the connection.

Visual Basic Example

     Dim conn As New MySql.Data.MySqlClient.MySqlConnection
     Dim myConnectionString as String

     myConnectionString = "server=127.0.0.1;" _
                 & "uid=root;" _
                 & "pwd=12345;" _
                 & "database=test;"

     Try
       conn.ConnectionString = myConnectionString
       conn.Open()

     Catch ex As MySql.Data.MySqlClient.MySqlException
       MessageBox.Show(ex.Message)
     End Try

C# Example

     MySql.Data.MySqlClient.MySqlConnection conn;
     string myConnectionString;

     myConnectionString = "server=127.0.0.1;uid=root;" +
         "pwd=12345;database=test;";

     try
     {
         conn = new MySql.Data.MySqlClient.MySqlConnection();
         conn.ConnectionString = myConnectionString;
         conn.Open();
     }
     catch (MySql.Data.MySqlClient.MySqlException ex)
     {
         MessageBox.Show(ex.Message);
     }

You can also pass the connection string to the constructor of the
`MySqlConnection' class:

Visual Basic Example

     Dim myConnectionString as String

     myConnectionString = "server=127.0.0.1;" _
                   & "uid=root;" _
                   & "pwd=12345;" _
                   & "database=test;"

     Try
         Dim conn As New MySql.Data.MySqlClient.MySqlConnection(myConnectionString)
         conn.Open()
     Catch ex As MySql.Data.MySqlClient.MySqlException
        MessageBox.Show(ex.Message)
     End Try

C# Example

     MySql.Data.MySqlClient.MySqlConnection conn;
     string myConnectionString;

     myConnectionString = "server=127.0.0.1;uid=root;" +
         "pwd=12345;database=test;";

     try
     {
         conn = new MySql.Data.MySqlClient.MySqlConnection(myConnectionString);
         conn.Open();
     }
     catch (MySql.Data.MySqlClient.MySqlException ex)
     {
         MessageBox.Show(ex.Message);
     }

Once the connection is open it can be used by the other Connector/NET
classes to communicate with the MySQL server.


File: manual.info,  Node: connector-net-using-connecting-errors,  Prev: connector-net-using-connecting-open,  Up: connector-net-using-connecting

30.2.5.5 Handling Connection Errors
...................................

Because connecting to an external server is unpredictable, it is
important to add error handling to your .NET application.  When there
is an error connecting, the `MySqlConnection' class will return a
`MySqlException' object. This object has two properties that are of
interest when handling errors:

   * `Message': A message that describes the current exception.

   * `Number': The MySQL error number.

When handling errors, you can your application's response based on the
error number. The two most common error numbers when connecting are as
follows:

   * `0': Cannot connect to server.

   * `1045': Invalid username and/or password.

The following code shows how to adapt the application's response based
on the actual error:

Visual Basic Example

     Dim myConnectionString as String

     myConnectionString = "server=127.0.0.1;" _
               & "uid=root;" _
               & "pwd=12345;" _
               & "database=test;"

     Try
         Dim conn As New MySql.Data.MySqlClient.MySqlConnection(myConnectionString)
         conn.Open()
     Catch ex As MySql.Data.MySqlClient.MySqlException
         Select Case ex.Number
             Case 0
                 MessageBox.Show("Cannot connect to server. Contact administrator")
             Case 1045
                 MessageBox.Show("Invalid username/password, please try again")
         End Select
     End Try

C# Example

     MySql.Data.MySqlClient.MySqlConnection conn;
     string myConnectionString;

     myConnectionString = "server=127.0.0.1;uid=root;" +
         "pwd=12345;database=test;";

     try
     {
         conn = new MySql.Data.MySqlClient.MySqlConnection(myConnectionString);
         conn.Open();
     }
         catch (MySql.Data.MySqlClient.MySqlException ex)
     {
         switch (ex.Number)
         {
             case 0:
                 MessageBox.Show("Cannot connect to server.  Contact administrator");
             case 1045:
                 MessageBox.Show("Invalid username/password, please try again");
         }
     }

*Important*:

Note that if you are using multilanguage databases you must specify the
character set in the connection string. If you do not specify the
character set, the connection defaults to the `latin1' charset. You can
specify the character set as part of the connection string, for example:

     MySqlConnection myConnection = new MySqlConnection("server=127.0.0.1;uid=root;" +
         "pwd=12345;database=test;Charset=latin1;");


File: manual.info,  Node: connector-net-using-prepared,  Next: connector-net-using-stored,  Prev: connector-net-using-connecting,  Up: connector-net-using

30.2.5.6 Using the Connector/NET with Prepared Statements
.........................................................

* Menu:

* connector-net-using-prepared-introduction::  Introduction
* connector-net-using-prepared-preparing::  Preparing Statements in Connector/NET


File: manual.info,  Node: connector-net-using-prepared-introduction,  Next: connector-net-using-prepared-preparing,  Prev: connector-net-using-prepared,  Up: connector-net-using-prepared

30.2.5.7 Introduction
.....................

As of MySQL 4.1, it is possible to use prepared statements with
Connector/NET. Use of prepared statements can provide significant
performance improvements on queries that are executed more than once.

Prepared execution is faster than direct execution for statements
executed more than once, primarily because the query is parsed only
once. In the case of direct execution, the query is parsed every time
it is executed. Prepared execution also can provide a reduction of
network traffic because for each execution of the prepared statement,
it is necessary only to send the data for the parameters.

Another advantage of prepared statements is that it uses a binary
protocol that makes data transfer between client and server more
efficient.


File: manual.info,  Node: connector-net-using-prepared-preparing,  Prev: connector-net-using-prepared-introduction,  Up: connector-net-using-prepared

30.2.5.8 Preparing Statements in Connector/NET
..............................................

To prepare a statement, create a command object and set the
`.CommandText' property to your query.

After entering your statement, call the `.Prepare' method of the
`MySqlCommand' object. After the statement is prepared, add parameters
for each of the dynamic elements in the query.

After you enter your query and enter parameters, execute the statement
using the `.ExecuteNonQuery()', `.ExecuteScalar()', or `.ExecuteReader'
methods.

For subsequent executions, you need only modify the values of the
parameters and call the execute method again, there is no need to set
the `.CommandText' property or redefine the parameters.

Visual Basic Example

     Dim conn As New MySqlConnection
     Dim cmd As New MySqlCommand

     conn.ConnectionString = strConnection

     Try
        conn.Open()
        cmd.Connection = conn

        cmd.CommandText = "INSERT INTO myTable VALUES(NULL, @number, @text)"
        cmd.Prepare()

        cmd.Parameters.Add("@number", 1)
        cmd.Parameters.Add("@text", "One")

        For i = 1 To 1000
            cmd.Parameters["@number"].Value = i
            cmd.Parameters["@text"].Value = "A string value"

            cmd.ExecuteNonQuery()
          Next
     Catch ex As MySqlException
         MessageBox.Show("Error " & ex.Number & " has occurred: " & ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
     End Try

C# Example

     MySql.Data.MySqlClient.MySqlConnection conn;
     MySql.Data.MySqlClient.MySqlCommand cmd;

     conn = new MySql.Data.MySqlClient.MySqlConnection();
     cmd = new MySql.Data.MySqlClient.MySqlCommand();

     conn.ConnectionString = strConnection;

     try
     {
         conn.Open();
         cmd.Connection = conn;

         cmd.CommandText = "INSERT INTO myTable VALUES(NULL, @number, @text)";
         cmd.Prepare();

         cmd.Parameters.Add("@number", 1);
         cmd.Parameters.Add("@text", "One");

         for (int i=1; i <= 1000; i++)
         {
             cmd.Parameters["@number"].Value = i;
             cmd.Parameters["@text"].Value = "A string value";

             cmd.ExecuteNonQuery();
         }
     }
     catch (MySql.Data.MySqlClient.MySqlException ex)
     {
         MessageBox.Show("Error " + ex.Number + " has occurred: " + ex.Message,
             "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
     }


File: manual.info,  Node: connector-net-using-stored,  Next: connector-net-using-blob,  Prev: connector-net-using-prepared,  Up: connector-net-using

30.2.5.9 Accessing Stored Procedures with Connector/NET
.......................................................

* Menu:

* connector-net-using-stored-introduction::  Introduction
* connector-net-using-stored-creating::  Creating Stored Procedures from Connector/NET
* connector-net-using-stored-calling::  Calling a Stored Procedure from Connector/NET


File: manual.info,  Node: connector-net-using-stored-introduction,  Next: connector-net-using-stored-creating,  Prev: connector-net-using-stored,  Up: connector-net-using-stored

30.2.5.10 Introduction
......................

With the release of MySQL version 5 the MySQL server now supports
stored procedures with the SQL 2003 stored procedure syntax.

A stored procedure is a set of SQL statements that can be stored in the
server. Once this has been done, clients don't need to keep reissuing
the individual statements but can refer to the stored procedure instead.

Stored procedures can be particularly useful in situations such as the
following:

   * When multiple client applications are written in different
     languages or work on different platforms, but need to perform the
     same database operations.

   * When security is paramount. Banks, for example, use stored
     procedures for all common operations. This provides a consistent
     and secure environment, and procedures can ensure that each
     operation is properly logged. In such a setup, applications and
     users would not get any access to the database tables directly,
     but can only execute specific stored procedures.

Connector/NET supports the calling of stored procedures through the
`MySqlCommand' object. Data can be passed in and our of a MySQL stored
procedure through use of the `MySqlCommand.Parameters' collection.

*Note*:

When you call a stored procedure, the command object makes an
additional `SELECT' call to determine the parameters of the stored
procedure. You must ensure that the user calling the procedure has the
`SELECT' privilege on the `mysql.proc' table to enable them to verify
the parameters. Failure to do this will result in an error when calling
the procedure.

This section will not provide in-depth information on creating Stored
Procedures. For such information, please refer to
`http://dev.mysql.com/doc/mysql/en/stored-procedures.html'.

A sample application demonstrating how to use stored procedures with
Connector/NET can be found in the `Samples' directory of your
Connector/NET installation.


File: manual.info,  Node: connector-net-using-stored-creating,  Next: connector-net-using-stored-calling,  Prev: connector-net-using-stored-introduction,  Up: connector-net-using-stored

30.2.5.11 Creating Stored Procedures from Connector/NET
.......................................................

Stored procedures in MySQL can be created using a variety of tools.
First, stored procedures can be created using the `mysql' command-line
client. Second, stored procedures can be created using the `MySQL Query
Browser' GUI client. Finally, stored procedures can be created using
the `.ExecuteNonQuery' method of the `MySqlCommand' object:

Visual Basic Example

     Dim conn As New MySqlConnection
     Dim cmd As New MySqlCommand

     conn.ConnectionString = "server=127.0.0.1;" _
         & "uid=root;" _
         & "pwd=12345;" _
         & "database=test"

     Try
         conn.Open()
         cmd.Connection = conn

         cmd.CommandText = "CREATE PROCEDURE add_emp(" _
             & "IN fname VARCHAR(20), IN lname VARCHAR(20), IN bday DATETIME, OUT empno INT) " _
             & "BEGIN INSERT INTO emp(first_name, last_name, birthdate) " _
             & "VALUES(fname, lname, DATE(bday)); SET empno = LAST_INSERT_ID(); END"

         cmd.ExecuteNonQuery()
     Catch ex As MySqlException
         MessageBox.Show("Error " & ex.Number & " has occurred: " & ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
     End Try

C# Example

     MySql.Data.MySqlClient.MySqlConnection conn;
     MySql.Data.MySqlClient.MySqlCommand cmd;

     conn = new MySql.Data.MySqlClient.MySqlConnection();
     cmd = new MySql.Data.MySqlClient.MySqlCommand();

     conn.ConnectionString = "server=127.0.0.1;uid=root;" +
         "pwd=12345;database=test;";

     try
     {
         conn.Open();
         cmd.Connection = conn;

         cmd.CommandText = "CREATE PROCEDURE add_emp(" +
             "IN fname VARCHAR(20), IN lname VARCHAR(20), IN bday DATETIME, OUT empno INT) " +
             "BEGIN INSERT INTO emp(first_name, last_name, birthdate) " +
             "VALUES(fname, lname, DATE(bday)); SET empno = LAST_INSERT_ID(); END";

         cmd.ExecuteNonQuery();
     }
     catch (MySql.Data.MySqlClient.MySqlException ex)
     {
     MessageBox.Show("Error " + ex.Number + " has occurred: " + ex.Message,
         "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
     }

It should be noted that, unlike the command-line and GUI clients, you
are not required to specify a special delimiter when creating stored
procedures in Connector/NET.


File: manual.info,  Node: connector-net-using-stored-calling,  Prev: connector-net-using-stored-creating,  Up: connector-net-using-stored

30.2.5.12 Calling a Stored Procedure from Connector/NET
.......................................................

To call a stored procedure using Connector/NET, create a `MySqlCommand'
object and pass the stored procedure name as the `.CommandText'
property. Set the `.CommandType' property to
`CommandType.StoredProcedure'.

After the stored procedure is named, create one `MySqlCommand'
parameter for every parameter in the stored procedure. `IN' parameters
are defined with the parameter name and the object containing the
value, `OUT' parameters are defined with the parameter name and the
datatype that is expected to be returned. All parameters need the
parameter direction defined.

After defining parameters, call the stored procedure by using the
`MySqlCommand.ExecuteNonQuery()' method:

Visual Basic Example

     Dim conn As New MySqlConnection
     Dim cmd As New MySqlCommand

     conn.ConnectionString = "server=127.0.0.1;" _
         & "uid=root;" _
         & "pwd=12345;" _
         & "database=test"

     Try
         conn.Open()
         cmd.Connection = conn

         cmd.CommandText = "add_emp"
         cmd.CommandType = CommandType.StoredProcedure

         cmd.Parameters.Add("@lname", 'Jones')
         cmd.Parameters["@lname"].Direction = ParameterDirection.Input

         cmd.Parameters.Add("@fname", 'Tom')
         cmd.Parameters["@fname"].Direction = ParameterDirection.Input

         cmd.Parameters.Add("@bday", #12/13/1977 2:17:36 PM#)
         cmd.Parameters["@bday"].Direction = ParameterDirection.Input

         cmd.Parameters.Add("@empno", MySqlDbType.Int32)
         cmd.Parameters["@empno"].Direction = ParameterDirection.Output

         cmd.ExecuteNonQuery()

         MessageBox.Show(cmd.Parameters["@empno"].Value)
     Catch ex As MySqlException
         MessageBox.Show("Error " & ex.Number & " has occurred: " & ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
     End Try

C# Example

     MySql.Data.MySqlClient.MySqlConnection conn;
     MySql.Data.MySqlClient.MySqlCommand cmd;

     conn = new MySql.Data.MySqlClient.MySqlConnection();
     cmd = new MySql.Data.MySqlClient.MySqlCommand();

     conn.ConnectionString = "server=127.0.0.1;uid=root;" +
         "pwd=12345;database=test;";

     try
     {
         conn.Open();
         cmd.Connection = conn;

         cmd.CommandText = "add_emp";
         cmd.CommandType = CommandType.StoredProcedure;

         cmd.Parameters.Add("@lname", "Jones");
         cmd.Parameters["@lname"].Direction = ParameterDirection.Input;

         cmd.Parameters.Add("@fname", "Tom");
         cmd.Parameters["@fname"].Direction = ParameterDirection.Input;

         cmd.Parameters.Add("@bday", DateTime.Parse("12/13/1977 2:17:36 PM"));
         cmd.Parameters["@bday"].Direction = ParameterDirection.Input;

         cmd.Parameters.Add("@empno", MySqlDbType.Int32);
         cmd.Parameters["@empno"].Direction = ParameterDirection.Output;

         cmd.ExecuteNonQuery();

         MessageBox.Show(cmd.Parameters["@empno"].Value);
     }
     catch (MySql.Data.MySqlClient.MySqlException ex)
     {
         MessageBox.Show("Error " + ex.Number + " has occurred: " + ex.Message,
           "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
     }

Once the stored procedure is called, the values of output parameters
can be retrieved by using the `.Value' property of the
`MySqlConnector.Parameters' collection.


File: manual.info,  Node: connector-net-using-blob,  Next: connector-net-using-crystal,  Prev: connector-net-using-stored,  Up: connector-net-using

30.2.5.13 Handling BLOB Data With Connector/NET
...............................................

* Menu:

* connector-net-using-blob-introduction::  Introduction
* connector-net-using-blob-serverprep::  Preparing the MySQL Server
* connector-net-using-blob-writing::  Writing a File to the Database
* connector-net-using-blob-reading::  Reading a BLOB from the Database to a File on Disk


File: manual.info,  Node: connector-net-using-blob-introduction,  Next: connector-net-using-blob-serverprep,  Prev: connector-net-using-blob,  Up: connector-net-using-blob

30.2.5.14 Introduction
......................

One common use for MySQL is the storage of binary data in `BLOB'
columns. MySQL supports four different BLOB datatypes: `TINYBLOB',
`BLOB', `MEDIUMBLOB', and `LONGBLOB'.

Data stored in a BLOB column can be accessed using Connector/NET and
manipulated using client-side code. There are no special requirements
for using Connector/NET with BLOB data.

Simple code examples will be presented within this section, and a full
sample application can be found in the `Samples' directory of the
Connector/NET installation.


File: manual.info,  Node: connector-net-using-blob-serverprep,  Next: connector-net-using-blob-writing,  Prev: connector-net-using-blob-introduction,  Up: connector-net-using-blob

30.2.5.15 Preparing the MySQL Server
....................................

The first step is using MySQL with BLOB data is to configure the
server. Let's start by creating a table to be accessed. In my file
tables, I usually have four columns: an AUTO_INCREMENT column of
appropriate size (UNSIGNED SMALLINT) to serve as a primary key to
identify the file, a VARCHAR column that stores the filename, an
UNSIGNED MEDIUMINT column that stores the size of the file, and a
MEDIUMBLOB column that stores the file itself. For this example, I will
use the following table definition:

     CREATE TABLE file(
     file_id SMALLINT UNSIGNED AUTO_INCREMENT NOT NULL PRIMARY KEY,
     file_name VARCHAR(64) NOT NULL,
     file_size MEDIUMINT UNSIGNED NOT NULL,
     file MEDIUMBLOB NOT NULL);

After creating a table, you may need to modify the max_allowed_packet
system variable. This variable determines how large of a packet (i.e. a
single row) can be sent to the MySQL server. By default, the server
will only accept a maximum size of 1 meg from our client application.
If you do not intend to exceed 1 meg, this should be fine. If you do
intend to exceed 1 meg in your file transfers, this number has to be
increased.

The max_allowed_packet option can be modified using MySQL
Administrator's Startup Variables screen. Adjust the Maximum allowed
option in the Memory section of the Networking tab to an appropriate
setting. After adjusting the value, click the `Apply Changes' button
and restart the server using the `Service Control' screen of MySQL
Administrator. You can also adjust this value directly in the my.cnf
file (add a line that reads max_allowed_packet=xxM), or use the SET
max_allowed_packet=xxM; syntax from within MySQL.

Try to be conservative when setting max_allowed_packet, as transfers of
BLOB data can take some time to complete. Try to set a value that will
be adequate for your intended use and increase the value if necessary.


File: manual.info,  Node: connector-net-using-blob-writing,  Next: connector-net-using-blob-reading,  Prev: connector-net-using-blob-serverprep,  Up: connector-net-using-blob

30.2.5.16 Writing a File to the Database
........................................

To write a file to a database we need to convert the file to a byte
array, then use the byte array as a parameter to an `INSERT' query.

The following code opens a file using a FileStream object, reads it
into a byte array, and inserts it into the `file' table:

Visual Basic Example

     Dim conn As New MySqlConnection
     Dim cmd As New MySqlCommand

     Dim SQL As String

     Dim FileSize As UInt32
     Dim rawData() As Byte
     Dim fs As FileStream

     conn.ConnectionString = "server=127.0.0.1;" _
         & "uid=root;" _
         & "pwd=12345;" _
         & "database=test"

     Try
         fs = New FileStream("c:\image.png", FileMode.Open, FileAccess.Read)
         FileSize = fs.Length

         rawData = New Byte(FileSize) {}
         fs.Read(rawData, 0, FileSize)
         fs.Close()

         conn.Open()

         SQL = "INSERT INTO file VALUES(NULL, @FileName, @FileSize, @File)"

         cmd.Connection = conn
         cmd.CommandText = SQL
         cmd.Parameters.Add("@FileName", strFileName)
         cmd.Parameters.Add("@FileSize", FileSize)
         cmd.Parameters.Add("@File", rawData)

         cmd.ExecuteNonQuery()

         MessageBox.Show("File Inserted into database successfully!", _
         "Success!", MessageBoxButtons.OK, MessageBoxIcon.Asterisk)

         conn.Close()
     Catch ex As Exception
         MessageBox.Show("There was an error: " & ex.Message, "Error", _
             MessageBoxButtons.OK, MessageBoxIcon.Error)
     End Try

C# Example

     MySql.Data.MySqlClient.MySqlConnection conn;
     MySql.Data.MySqlClient.MySqlCommand cmd;

     conn = new MySql.Data.MySqlClient.MySqlConnection();
     cmd = new MySql.Data.MySqlClient.MySqlCommand();

     string SQL;
     UInt32 FileSize;
     byte[] rawData;
     FileStream fs;

     conn.ConnectionString = "server=127.0.0.1;uid=root;" +
         "pwd=12345;database=test;";

     try
     {
         fs = new FileStream(@"c:\image.png", FileMode.Open, FileAccess.Read);
         FileSize = fs.Length;

         rawData = new byte[FileSize];
         fs.Read(rawData, 0, FileSize);
         fs.Close();

         conn.Open();

         SQL = "INSERT INTO file VALUES(NULL, @FileName, @FileSize, @File)";

         cmd.Connection = conn;
         cmd.CommandText = SQL;
         cmd.Parameters.Add("@FileName", strFileName);
         cmd.Parameters.Add("@FileSize", FileSize);
         cmd.Parameters.Add("@File", rawData);

         cmd.ExecuteNonQuery();

         MessageBox.Show("File Inserted into database successfully!",
             "Success!", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);

         conn.Close();
     }
     catch (MySql.Data.MySqlClient.MySqlException ex)
     {
         MessageBox.Show("Error " + ex.Number + " has occurred: " + ex.Message,
             "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
     }

The `Read' method of the `FileStream' object is used to load the file
into a byte array which is sized according to the `Length' property of
the FileStream object.

After assigning the byte array as a parameter of the `MySqlCommand'
object, the `ExecuteNonQuery' method is called and the BLOB is inserted
into the `file' table.


File: manual.info,  Node: connector-net-using-blob-reading,  Prev: connector-net-using-blob-writing,  Up: connector-net-using-blob

30.2.5.17 Reading a BLOB from the Database to a File on Disk
............................................................

Once a file is loaded into the `file' table, we can use the
`MySqlDataReader' class to retrieve it.

The following code retrieves a row from the `file' table, then loads
the data into a `FileStream' object to be written to disk:

Visual Basic Example

     Dim conn As New MySqlConnection
     Dim cmd As New MySqlCommand
     Dim myData As MySqlDataReader
     Dim SQL As String
     Dim rawData() As Byte
     Dim FileSize As UInt32
     Dim fs As FileStream

     conn.ConnectionString = "server=127.0.0.1;" _
         & "uid=root;" _
         & "pwd=12345;" _
         & "database=test"

     SQL = "SELECT file_name, file_size, file FROM file"

     Try
         conn.Open()

         cmd.Connection = conn
         cmd.CommandText = SQL

         myData = cmd.ExecuteReader

         If Not myData.HasRows Then Throw New Exception("There are no BLOBs to save")

         myData.Read()

         FileSize = myData.GetUInt32(myData.GetOrdinal("file_size"))
         rawData = New Byte(FileSize) {}

         myData.GetBytes(myData.GetOrdinal("file"), 0, rawData, 0, FileSize)

         fs = New FileStream("C:\newfile.png", FileMode.OpenOrCreate, FileAccess.Write)
         fs.Write(rawData, 0, FileSize)
         fs.Close()

         MessageBox.Show("File successfully written to disk!", "Success!", MessageBoxButtons.OK, MessageBoxIcon.Asterisk)

         myData.Close()
         conn.Close()
     Catch ex As Exception
         MessageBox.Show("There was an error: " & ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
     End Try

C# Example

     MySql.Data.MySqlClient.MySqlConnection conn;
     MySql.Data.MySqlClient.MySqlCommand cmd;
     MySql.Data.MySqlClient.MySqlDataReader myData;

     conn = new MySql.Data.MySqlClient.MySqlConnection();
     cmd = new MySql.Data.MySqlClient.MySqlCommand();

     string SQL;
     UInt32 FileSize;
     byte[] rawData;
     FileStream fs;

     conn.ConnectionString = "server=127.0.0.1;uid=root;" +
         "pwd=12345;database=test;";

     SQL = "SELECT file_name, file_size, file FROM file";

     try
     {
         conn.Open();

         cmd.Connection = conn;
         cmd.CommandText = SQL;

         myData = cmd.ExecuteReader();

         if (! myData.HasRows)
             throw new Exception("There are no BLOBs to save");

         myData.Read();

         FileSize = myData.GetUInt32(myData.GetOrdinal("file_size"));
         rawData = new byte[FileSize];

         myData.GetBytes(myData.GetOrdinal("file"), 0, rawData, 0, FileSize);

         fs = new FileStream(@"C:\newfile.png", FileMode.OpenOrCreate, FileAccess.Write);
         fs.Write(rawData, 0, FileSize);
         fs.Close();

         MessageBox.Show("File successfully written to disk!",
             "Success!", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);

         myData.Close();
         conn.Close();
     }
     catch (MySql.Data.MySqlClient.MySqlException ex)
     {
         MessageBox.Show("Error " + ex.Number + " has occurred: " + ex.Message,
             "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
     }

After connecting, the contents of the `file' table are loaded into a
`MySqlDataReader' object. The `GetBytes' method of the MySqlDataReader
is used to load the BLOB into a byte array, which is then written to
disk using a FileStream object.

The `GetOrdinal' method of the MySqlDataReader can be used to determine
the integer index of a named column. Use of the GetOrdinal method
prevents errors if the column order of the `SELECT' query is changed.


File: manual.info,  Node: connector-net-using-crystal,  Next: connector-net-using-datetime,  Prev: connector-net-using-blob,  Up: connector-net-using

30.2.5.18 Using Connector/NET with Crystal Reports
..................................................

* Menu:

* connector-net-using-crystal-introduction::  Introduction
* connector-net-using-crystal-source::  Creating a Data Source
* connector-net-using-crystal-creating::  Creating the Report
* connector-net-using-crystal-displaying::  Displaying the Report


File: manual.info,  Node: connector-net-using-crystal-introduction,  Next: connector-net-using-crystal-source,  Prev: connector-net-using-crystal,  Up: connector-net-using-crystal

30.2.5.19 Introduction
......................

Crystal Reports is a common tool used by Windows application developers
to perform reporting and document generation. In this section we will
show how to use Crystal Reports XI with MySQL and Connector/NET.


File: manual.info,  Node: connector-net-using-crystal-source,  Next: connector-net-using-crystal-creating,  Prev: connector-net-using-crystal-introduction,  Up: connector-net-using-crystal

30.2.5.20 Creating a Data Source
................................

When creating a report in Crystal Reports there are two options for
accessing the MySQL data while designing your report.

The first option is to use Connector/ODBC as an ADO data source when
designing your report. You will be able to browse your database and
choose tables and fields using drag and drop to build your report. The
disadvantage of this approach is that additional work must be performed
within your application to produce a data set that matches the one
expected by your report.

The second option is to create a data set in VB.NET and save it as XML.
This XML file can then be used to design a report.  This works quite
well when displaying the report in your application, but is less
versatile at design time because you must choose all relevant columns
when creating the data set.  If you forget a column you must re-create
the data set before the column can be added to the report.

The following code can be used to create a data set from a query and
write it to disk:

Visual Basic Example

     Dim myData As New DataSet
     Dim conn As New MySqlConnection
     Dim cmd As New MySqlCommand
     Dim myAdapter As New MySqlDataAdapter

     conn.ConnectionString = "server=127.0.0.1;" _
         & "uid=root;" _
         & "pwd=12345;" _
         & "database=world"

     Try
         conn.Open()
         cmd.CommandText = "SELECT city.name AS cityName, city.population AS CityPopulation, " _
             & "country.name, country.population, country.continent " _
             & "FROM country, city ORDER BY country.continent, country.name"
         cmd.Connection = conn

         myAdapter.SelectCommand = cmd
         myAdapter.Fill(myData)

         myData.WriteXml("C:\dataset.xml", XmlWriteMode.WriteSchema)
     Catch ex As Exception
         MessageBox.Show(ex.Message, "Report could not be created", MessageBoxButtons.OK, MessageBoxIcon.Error)
     End Try

C# Example

     DataSet myData = new DataSet();
     MySql.Data.MySqlClient.MySqlConnection conn;
     MySql.Data.MySqlClient.MySqlCommand cmd;
     MySql.Data.MySqlClient.MySqlDataAdapter myAdapter;

     conn = new MySql.Data.MySqlClient.MySqlConnection();
     cmd = new MySql.Data.MySqlClient.MySqlCommand();
     myAdapter = new MySql.Data.MySqlClient.MySqlDataAdapter();

     conn.ConnectionString = "server=127.0.0.1;uid=root;" +
       "pwd=12345;database=test;";

     try
     {
       cmd.CommandText = "SELECT city.name AS cityName, city.population AS CityPopulation, " +
       "country.name, country.population, country.continent " +
       "FROM country, city ORDER BY country.continent, country.name";
       cmd.Connection = conn;

       myAdapter.SelectCommand = cmd;
       myAdapter.Fill(myData);

       myData.WriteXml(@"C:\dataset.xml", XmlWriteMode.WriteSchema);
     }
     catch (MySql.Data.MySqlClient.MySqlException ex)
     {
       MessageBox.Show(ex.Message, "Report could not be created",
       MessageBoxButtons.OK, MessageBoxIcon.Error);
     }

The resulting XML file can be used as an ADO.NET XML datasource when
designing your report.

If you choose to design your reports using Connector/ODBC, it can be
downloaded from dev.mysql.com
(http://dev.mysql.com/downloads/connector/odbc/3.51.html).


File: manual.info,  Node: connector-net-using-crystal-creating,  Next: connector-net-using-crystal-displaying,  Prev: connector-net-using-crystal-source,  Up: connector-net-using-crystal

30.2.5.21 Creating the Report
.............................

For most purposes the Standard Report wizard should help with the
initial creation of a report. To start the wizard, open Crystal Reports
and choose the New > Standard Report option from the File menu.

The wizard will first prompt you for a data source. If you are using
Connector/ODBC as your data source, use the OLEDB provider for ODBC
option from the OLE DB (ADO) tree instead of the ODBC (RDO) tree when
choosing a data source. If using a saved data set, choose the ADO.NET
(XML) option and browse to your saved data set.

The remainder of the report creation process is done automatically by
the wizard.

After the report is created, choose the Report Options...  entry of the
File menu. Un-check the Save Data With Report option. This prevents
saved data from interfering with the loading of data within our
application.


File: manual.info,  Node: connector-net-using-crystal-displaying,  Prev: connector-net-using-crystal-creating,  Up: connector-net-using-crystal

30.2.5.22 Displaying the Report
...............................

To display a report we first populate a data set with the data needed
for the report, then load the report and bind it to the data set.
Finally we pass the report to the crViewer control for display to the
user.

The following references are needed in a project that displays a report:

   * CrytalDecisions.CrystalReports.Engine

   * CrystalDecisions.ReportSource

   * CrystalDecisions.Shared

   * CrystalDecisions.Windows.Forms

The following code assumes that you created your report using a data
set saved using the code shown in *Note
connector-net-using-crystal-source::, and have a crViewer control on
your form named `myViewer'.

Visual Basic Example

     Imports CrystalDecisions.CrystalReports.Engine
     Imports System.Data
     Imports MySql.Data.MySqlClient

     Dim myReport As New ReportDocument
     Dim myData As New DataSet
     Dim conn As New MySqlConnection
     Dim cmd As New MySqlCommand
     Dim myAdapter As New MySqlDataAdapter

     conn.ConnectionString = _
         "server=127.0.0.1;" _
         & "uid=root;" _
         & "pwd=12345;" _
         & "database=test"

     Try
         conn.Open()

         cmd.CommandText = "SELECT city.name AS cityName, city.population AS CityPopulation, " _
             & "country.name, country.population, country.continent " _
             & "FROM country, city ORDER BY country.continent, country.name"
         cmd.Connection = conn

         myAdapter.SelectCommand = cmd
         myAdapter.Fill(myData)

         myReport.Load(".\world_report.rpt")
         myReport.SetDataSource(myData)
         myViewer.ReportSource = myReport
     Catch ex As Exception
         MessageBox.Show(ex.Message, "Report could not be created", MessageBoxButtons.OK, MessageBoxIcon.Error)
     End Try

C# Example

     using CrystalDecisions.CrystalReports.Engine;
     using System.Data;
     using MySql.Data.MySqlClient;

     ReportDocument myReport = new ReportDocument();
     DataSet myData = new DataSet();
     MySql.Data.MySqlClient.MySqlConnection conn;
     MySql.Data.MySqlClient.MySqlCommand cmd;
     MySql.Data.MySqlClient.MySqlDataAdapter myAdapter;

     conn = new MySql.Data.MySqlClient.MySqlConnection();
     cmd = new MySql.Data.MySqlClient.MySqlCommand();
     myAdapter = new MySql.Data.MySqlClient.MySqlDataAdapter();

     conn.ConnectionString = "server=127.0.0.1;uid=root;" +
         "pwd=12345;database=test;";

     try
     {
         cmd.CommandText = "SELECT city.name AS cityName, city.population AS CityPopulation, " +
             "country.name, country.population, country.continent " +
             "FROM country, city ORDER BY country.continent, country.name";
         cmd.Connection = conn;

         myAdapter.SelectCommand = cmd;
         myAdapter.Fill(myData);

         myReport.Load(@".\world_report.rpt");
         myReport.SetDataSource(myData);
         myViewer.ReportSource = myReport;
     }
     catch (MySql.Data.MySqlClient.MySqlException ex)
     {
         MessageBox.Show(ex.Message, "Report could not be created",
             MessageBoxButtons.OK, MessageBoxIcon.Error);
     }

A new data set it generated using the same query used to generate the
previously saved data set. Once the data set is filled, a
ReportDocument is used to load the report file and bind it to the data
set. The ReportDocument is the passed as the ReportSource of the
crViewer.

This same approach is taken when a report is created from a single
table using Connector/ODBC. The data set replaces the table used in the
report and the report is displayed properly.

When a report is created from multiple tables using Connector/ODBC, a
data set with multiple tables must be created in our application. This
allows each table in the report data source to be replaced with a
report in the data set.

We populate a data set with multiple tables by providing multiple
`SELECT' statements in our MySqlCommand object. These `SELECT'
statements are based on the SQL query shown in Crystal Reports in the
Database menu's Show SQL Query option. Assume the following query:

     SELECT `country`.`Name`, `country`.`Continent`, `country`.`Population`, `city`.`Name`, `city`.`Population`
     FROM `world`.`country` `country` LEFT OUTER JOIN `world`.`city` `city` ON `country`.`Code`=`city`.`CountryCode`
     ORDER BY `country`.`Continent`, `country`.`Name`, `city`.`Name`

This query is converted to two `SELECT' queries and displayed with the
following code:

Visual Basic Example

     Imports CrystalDecisions.CrystalReports.Engine
     Imports System.Data
     Imports MySql.Data.MySqlClient

     Dim myReport As New ReportDocument
     Dim myData As New DataSet
     Dim conn As New MySqlConnection
     Dim cmd As New MySqlCommand
     Dim myAdapter As New MySqlDataAdapter

     conn.ConnectionString = "server=127.0.0.1;" _
         & "uid=root;" _
         & "pwd=12345;" _
         & "database=world"

     Try
         conn.Open()
         cmd.CommandText = "SELECT name, population, countrycode FROM city ORDER BY countrycode, name; " _
             & "SELECT name, population, code, continent FROM country ORDER BY continent, name"
         cmd.Connection = conn

         myAdapter.SelectCommand = cmd
         myAdapter.Fill(myData)

         myReport.Load(".\world_report.rpt")
         myReport.Database.Tables(0).SetDataSource(myData.Tables(0))
         myReport.Database.Tables(1).SetDataSource(myData.Tables(1))
         myViewer.ReportSource = myReport
     Catch ex As Exception
         MessageBox.Show(ex.Message, "Report could not be created", MessageBoxButtons.OK, MessageBoxIcon.Error)
     End Try

C# Example

     using CrystalDecisions.CrystalReports.Engine;
     using System.Data;
     using MySql.Data.MySqlClient;

     ReportDocument myReport = new ReportDocument();
     DataSet myData = new DataSet();
     MySql.Data.MySqlClient.MySqlConnection conn;
     MySql.Data.MySqlClient.MySqlCommand cmd;
     MySql.Data.MySqlClient.MySqlDataAdapter myAdapter;

     conn = new MySql.Data.MySqlClient.MySqlConnection();
     cmd = new MySql.Data.MySqlClient.MySqlCommand();
     myAdapter = new MySql.Data.MySqlClient.MySqlDataAdapter();

     conn.ConnectionString = "server=127.0.0.1;uid=root;" +
         "pwd=12345;database=test;";

     try
     {
         cmd.CommandText = "SELECT name, population, countrycode FROM city ORDER " +
             "BY countrycode, name; `SELECT' name, population, code, continent FROM " +
             "country ORDER BY continent, name";
         cmd.Connection = conn;

         myAdapter.SelectCommand = cmd;
         myAdapter.Fill(myData);

         myReport.Load(@".\world_report.rpt");
         myReport.Database.Tables(0).SetDataSource(myData.Tables(0));
         myReport.Database.Tables(1).SetDataSource(myData.Tables(1));
         myViewer.ReportSource = myReport;
     }
     catch (MySql.Data.MySqlClient.MySqlException ex)
     {
         MessageBox.Show(ex.Message, "Report could not be created",
             MessageBoxButtons.OK, MessageBoxIcon.Error);
     }

It is important to order the `SELECT' queries in alphabetical order, as
this is the order the report will expect its source tables to be in.
One SetDataSource statement is needed for each table in the report.

This approach can cause performance problems because Crystal Reports
must bind the tables together on the client-side, which will be slower
than using a pre-saved data set.


File: manual.info,  Node: connector-net-using-datetime,  Next: connector-net-using-faq,  Prev: connector-net-using-crystal,  Up: connector-net-using

30.2.5.23 Handling Date and Time Information in Connector/NET
.............................................................

* Menu:

* connector-net-using-datetime-introduction::  Introduction
* connector-net-using-datetime-problems::  Problems when Using Invalid Dates
* connector-net-using-datetime-restricting::  Restricting Invalid Dates
* connector-net-using-datetime-invalid::  Handling Invalid Dates
* connector-net-using-datetime-null::  Handling NULL Dates


File: manual.info,  Node: connector-net-using-datetime-introduction,  Next: connector-net-using-datetime-problems,  Prev: connector-net-using-datetime,  Up: connector-net-using-datetime

30.2.5.24 Introduction
......................

MySQL and the .NET languages handle date and time information
differently, with MySQL allowing dates that cannot be represented by a
.NET data type, such as '`0000-00-00 00:00:00''. These differences can
cause problems if not properly handled.

In this section we will demonstrate how to properly handle date and
time information when using Connector/NET.


File: manual.info,  Node: connector-net-using-datetime-problems,  Next: connector-net-using-datetime-restricting,  Prev: connector-net-using-datetime-introduction,  Up: connector-net-using-datetime

30.2.5.25 Problems when Using Invalid Dates
...........................................

The differences in date handling can cause problems for developers who
use invalid dates. Invalid MySQL dates cannot be loaded into native
.NET `DateTime' objects, including `NULL' dates.

Because of this issue, .NET `DataSet' objects cannot be populated by
the `Fill' method of the `MySqlDataAdapter' class as invalid dates will
cause a `System.ArgumentOutOfRangeException' exception to occur.


File: manual.info,  Node: connector-net-using-datetime-restricting,  Next: connector-net-using-datetime-invalid,  Prev: connector-net-using-datetime-problems,  Up: connector-net-using-datetime

30.2.5.26 Restricting Invalid Dates
...................................

The best solution to the date problem is to restrict users from
entering invalid dates. This can be done on either the client or the
server side.

Restricting invalid dates on the client side is as simple as always
using the .NET `DateTime' class to handle dates. The `DateTime' class
will only allow valid dates, ensuring that the values in your database
are also valid. The disadvantage of this is that it is not useful in a
mixed environment where .NET and non .NET code are used to manipulate
the database, as each application must perform its own date validation.

Users of MySQL 5.0.2 and higher can use the new `traditional' SQL mode
to restrict invalid date values. For information on using the
`traditional' SQL mode, see *Note server-sql-mode::.


File: manual.info,  Node: connector-net-using-datetime-invalid,  Next: connector-net-using-datetime-null,  Prev: connector-net-using-datetime-restricting,  Up: connector-net-using-datetime

30.2.5.27 Handling Invalid Dates
................................

Although it is strongly recommended that you avoid the use of invalid
dates within your .NET application, it is possible to use invalid dates
by means of the `MySqlDateTime' datatype.

The `MySqlDateTime' datatype supports the same date values that are
supported by the MySQL server. The default behavior of Connector/NET is
to return a .NET DateTime object for valid date values, and return an
error for invalid dates. This default can be modified to cause
Connector/NET to return `MySqlDateTime' objects for invalid dates.

To instruct Connector/NET to return a `MySqlDateTime' object for
invalid dates, add the following line to your connection string:

       Allow Zero Datetime=True

Please note that the use of the `MySqlDateTime' class can still be
problematic. The following are some known issues:

  1. Data binding for invalid dates can still cause errors (zero dates
     like 0000-00-00 do not seem to have this problem).

  2. The `ToString' method return a date formatted in the standard
     MySQL format (for example, `2005-02-23 08:50:25'). This differs
     from the `ToString' behavior of the .NET DateTime class.

  3. The `MySqlDateTime' class supports NULL dates, while the .NET
     DateTime class does not. This can cause errors when trying to
     convert a MySQLDateTime to a DateTime if you do not check for NULL
     first.

Because of the known issues, the best recommendation is still to use
only valid dates in your application.


File: manual.info,  Node: connector-net-using-datetime-null,  Prev: connector-net-using-datetime-invalid,  Up: connector-net-using-datetime

30.2.5.28 Handling NULL Dates
.............................

The .NET `DateTime' datatype cannot handle `NULL' values. As such, when
assigning values from a query to a `DateTime' variable, you must first
check whether the value is in fact `NULL'.

When using a `MySqlDataReader', use the `.IsDBNull' method to check
whether a value is `NULL' before making the assignment:

Visual Basic Example

     If Not myReader.IsDBNull(myReader.GetOrdinal("mytime")) Then
         myTime = myReader.GetDateTime(myReader.GetOrdinal("mytime"))
     Else
         myTime = DateTime.MinValue
     End If

C# Example

     if (! myReader.IsDBNull(myReader.GetOrdinal("mytime")))
         myTime = myReader.GetDateTime(myReader.GetOrdinal("mytime"));
     else
         myTime = DateTime.MinValue;

`NULL' values will work in a data set and can be bound to form controls
without special handling.


File: manual.info,  Node: connector-net-using-faq,  Prev: connector-net-using-datetime,  Up: connector-net-using

30.2.5.29 Frequently Asked Questions
....................................

The following details a number of frequently asked questions about
Connector/NET.

*Questions*
   * 31.2.5.7.1: How do I obtain the value of an auto-incremented
     column?

*Questions and Answers* *31.2.5.7.1: ** How do I obtain the value of an
auto-incremented column?  *

When using the commandBuilder you should make sure that you set the
`ReturnGeneratedIdentifiers' property to `true'.

Then, you can use an active view on a table to access the updated ID.
For example:

     				conn = new MySql.Data.MySqlClient.MySqlConnection();
     				cmd = new MySql.Data.MySqlClient.MySqlCommand();
     				da = new MySql.Data.MySqlClient.MySqlDataAdapter();
     				cmdBuilder = new MySql.Data.MySqlClient.MySqlCommandBuilder();
     				SystemDataDataSet = new System.Data.DataSet();
     				SystemDataDataView = new System.Data.DataView();
     ...
             cmd.Connection = conn;
             cmd.CommandText = "SELECT * FROM contacts";
     			  da.SelectCommand = cmd;
             da.Fill(SystemDataDataSet, "contacts");
     				cmdBuilder.DataAdapter = da;
             cmdBuilder.ReturnGeneratedIdentifiers = true;
             cmdBuilder.DataAdapter.SelectCommand.CommandText = "SELECT * FROM contacts";
     				cmdBuilder.RefreshSchema();

             SystemDataDataView = SystemDataDataSet.Tables["contacts"].DefaultView;

     				SystemDataDataRow = SystemDataDataView.Table.NewRow();
             SystemDataDataRow["status"] = 1;

             SystemDataDataView.Table.Rows.Add(SystemDataDataRow);
             da.Update(SystemDataDataSet, "contacts");
             System.Console.WriteLine("ID after update: "  + SystemDataDataRow["id"]);

The `SystemDataDataRow' object in this instance provides the interface
to the updated auto-increment value in the `id' column.


File: manual.info,  Node: connect-net-support,  Prev: connector-net-using,  Up: connector-net

30.2.6 Connector/NET Support
----------------------------

* Menu:

* connector-net-support-community::  Connector/NET Community Support
* connector-net-support-bug-report::  How to report Connector/NET Problems or Bugs
* connector-net-support-changehistory::  Connector/NET Change History

The developers of Connector/NET greatly value the input of our users in
the software development process. If you find Connector/NET lacking
some feature important to you, or if you discover a bug and need to
file a bug report, please use the instructions in *Note bug-reports::.


File: manual.info,  Node: connector-net-support-community,  Next: connector-net-support-bug-report,  Prev: connect-net-support,  Up: connect-net-support

30.2.6.1 Connector/NET Community Support
........................................

   * Community support for Connector/NET can be found through the
     forums at `http://forums.mysql.com'.

   * Community support for Connector/NET can also be found through the
     mailing lists at `http://lists.mysql.com'.

   * Paid support is available from MySQL AB. Additional information is
     available at `http://www.mysql.com/support/'.


File: manual.info,  Node: connector-net-support-bug-report,  Next: connector-net-support-changehistory,  Prev: connector-net-support-community,  Up: connect-net-support

30.2.6.2 How to report Connector/NET Problems or Bugs
.....................................................

If you encounter difficulties or problems with Connector/NET, contact
the Connector/NET community *Note connector-net-support-community::.

You should first try to execute the same SQL statements and commands
from the `mysql' client program or from `admndemo'. This helps you
determine whether the error is in Connector/NET or MySQL.

If reporting a problem, you should ideally include the following
information with the email:

   * Operating system and version

   * Connector/NET version

   * MySQL server version

   * Copies of error messages or other unexpected output

   * Simple reproducible sample

Remember that the more information you can supply to us, the more
likely it is that we can fix the problem.

If you believe the problem to be a bug, then you must report the bug
through `http://bugs.mysql.com/'.


File: manual.info,  Node: connector-net-support-changehistory,  Prev: connector-net-support-bug-report,  Up: connect-net-support

30.2.6.3 Connector/NET Change History
.....................................

The Connector/NET Change History (Changelog) is located with the main
Changelog for MySQL. See *Note connector-net-news::.


File: manual.info,  Node: connector-vstudio,  Next: connector-j,  Prev: connector-net,  Up: connectors

30.3 MySQL Visual Studio Plugin
===============================

* Menu:

* connector-vstudio-install::    Installing the MySQL Visual Studio Plugin
* connector-vstudio-creating::   Creating a connection to the MySQL server
* connector-vstudio-using::      Using the MySQL Visual Studio Plugin
* connector-vstudio-support::    Visual Studio Plugin Support

The MySQL Visual Studio Plugin is a DDEX provider; a plug-in for Visual
Studio 2005 that allows developers to maintain database structures, and
supports built-in data-driven application development tools.

The current version of the MySQL Visual Studio Plugin includes only
database maintenance tools. Data-driven application development tools
are not supported.

The MySQL DDEX Provider operates as a standard extension to the Visual
Studio Data Designer functionality available through the Server
Explorer menu of Visual Studio 2005, and enables developers to create
database objects and data within a MySQL database.

The MySQL Visual Studio Plugin is designed to work with MySQL version
5.0, but is also compatible with MySQL 4.1.1 and provides limited
compatibility with MySQL 5.1.


File: manual.info,  Node: connector-vstudio-install,  Next: connector-vstudio-creating,  Prev: connector-vstudio,  Up: connector-vstudio

30.3.1 Installing the MySQL Visual Studio Plugin
------------------------------------------------

The MySQL Visual Studio Plugin requires one of Visual Studio 2005
Standard, Professional or Team Developer Edition to be installed.
Other editions of Visual Studio 2005 are not supported.

*Note*:

Starting with Connector/NET 5.1.2, the Visual Studio Plugin is included
in the installation. If you have installed Connector/NET 5.1.2, then
you do not need to separately install the Visual Studio Plugin.

Here is the list of components that should already be installed before
starting the installation of the MySQL Visual Studio Plugin:

   * Visual Studio 2005 Standard, Professional or Team Developer
     Edition.

   * MySQL Server 4.1.1 or later (either installed on the same machine,
     or a separate server).

   * MySQL Connector/NET 5.0.

*Note*:

When installing Connector/NET you must ensure that the connector is
installed into the Global Assembly Cache (GAC). The Connector/NET
installer handles this for you automatically, but in a custom
installation the option may have been disabled.

The user used to connect to the MySQL server must have the following
privileges to use the functionality provided by the MySQL Visual Studio
Plugin:

   * The `SELECT' privilege for the `INFORMATION_SCHEMA' database.

   * The `EXECUTE' privilege for the `SHOW CREATE TABLE' statement.

   * The `SELECT' privilege for the `mysql.proc' table (required for
     operations with stored procedures and functions).

   * The `SELECT' privilege for the `mysql.func' table (required for
     operations with User Defined Functions (UDF)).

   * The `EXECUTE' privilege for the `SHOW ENGINE STATUS' statement
     (required for retrieving extended error information).

   * Appropriate privileges for performed operations (e.g. the `SELECT'
     privilege is required to browse data from a table etc.).

The MySQL Visual Studio Plugin is delivered as a MSI package that can
be used to install, uninstall or reinstall the Provider. If you are not
using Windows XP or Windows Server 2003 you upgrade the Windows
Installer system to the latest version (see
http://support.microsoft.com/default.aspx?scid=kb;EN-US;292539
(http://support.microsoft.com/default.aspx?scid=kb;EN-US;292539) for
details).

The MSI-package is named `MySQL.VisualStudio.msi'. To install the MySQL
Visual Studio Plugin, right click on the MSI file and select `Install'.
The installation process is as follow:

  1. The standard Welcome dialog is opened. Click Next to continue
     installation.

  2. The License agreement (GNU GPL) window is opened. Accept the
     agreement and click `Next' to continue.

  3. The destination folder choice dialog is opened. Here you can point
     out the folder where the MySQL Visual Studio Plugin will be
     installed. The default destination folder is
     `%ProgramFilesDir%\MySQL\MySQL DDEX Data Provider', where
     `%ProgramFilesDir%' is the Program Files folder of the
     installation machine. After choosing the destination folder, click
     `Next' to continue.

  4. The installer will ask to confirm that installation. Click Install
     to start installation process.

  5. The installation will now take place. At the end of this step the
     Visual Studio command table is rebuilt (this process may take
     several minutes).

  6. Once installation is complete, click `Finish' to end the
     installation process.

To uninstall the MySQL Visual Studio Plugin, you can use either
Add/Remove Programs component of the Control Panel or the same
MSI-package. Choose the `Remove' option, and the Provider will be
uninstalled automatically.

To repair the Provider, right click the MSI-package and choose the
`Repair' option. The MySQL Visual Studio Plugin will be repaired
automatically.

The installation package includes the following files:

   * `MySQL.VisualStudio.dll' -- the MySQL DDEX Provider assembly.

   * `MySQL.Data.dll' -- the assembly containing the MySQL Connector
     .NET which is used by the Provider.

   * `MySql.VisualStudio.dll.config' -- the configuration file for the
     MySQL Visual Studio Plugin. This file contains default values for
     the provider GUI layout.

     *Note*:

     Do not remove this file before the first use of the Provider.

   * `Register.reg' -- the file with registry entries that can be used
     to register the MySQL DDEX Provider in the case of the manual
     installation.

   * `Install.js' -- the script used to register the Connector .NET as
     an ADO.NET data provider in the machine.config file.

   * `Release notes.doc' -- the document with release notes.

To install the Provider manually, copy all files of the installation
package in a desired folder, then set the full path to the Provider
assembly as a value of the CodeBase entry. For example:

     [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\VisualStudio\8.0\Packages\{79A115C9-B133-4891-9E7B-242509DAD272}]@="MySql.Data.VisualStudio.MySqlDataProviderPackage"
     "InprocServer32"="C:\\WINNT\\system32\\mscoree.dll"
     "Class"="MySql.Data.VisualStudio.MySqlDataProviderPackage"
     "CodeBase"="C:\\MySqlDdexProvider\\MySql.VisualStudio.dll"

Then import information from the Register.reg file to the registry by
clicking of the file. At the confirmation dialog choose Yes.  Next you
must run the command devenv.exe /setup within a Command Prompt to
rebuild the Visual Studio command table.


File: manual.info,  Node: connector-vstudio-creating,  Next: connector-vstudio-using,  Prev: connector-vstudio-install,  Up: connector-vstudio

30.3.2 Creating a connection to the MySQL server
------------------------------------------------

Once the MySQL Visual Studio Plugin is installed, you can use it to
create, modify and delete connections to MySQL databases. To create a
connection with a MySQL database, perform the following steps:

  1. Start Visual Studio 2005 and open Server Explorer window by
     choosing the `Server Explorer' option from the `View' menu.

  2. Right click on the `Data Connections' node and choose the `Add
     Connection' button.

  3. The Add Connection dialog is opened. Press the `Change' button to
     choose MySQL Database as a data source.

  4. Change Data Source dialog is opened. Choose MySQL Database in the
     list of data sources (or the `other' option, if MySQL Database is
     absent), and then choose `.NET Framework Data Provider for MySQL'
     in the combo box of data providers.

     Choosing a data source

     Press `OK' to confirm your choice.

  5. Enter the connection settings: the server host name (for example,
     localhost if the MySQL server is installed on the local machine),
     the user name, the password, and the default database schema. Note
     that you must specify the default schema name to open the
     connection.

     Setting connection properties

  6. You can also set the port to connect with the MySQL server by
     pressing the `Advanced' button. To test a connection with the
     MySQL server, ser the server host name, the user name, and the
     password, and press the `Test Connection' button. If the test
     fails, check the connection values that you have supplied are
     correct and that the corresponding user and privileges have been
     configured on the MySQL server.

  7. After you set all settings and test the connection, press `OK'.
     The newly created connection is displayed in Server Explorer. Now
     you can work with the MySQL server through standard Server
     Explorer interface.

After a connection is successfully established, all the connection
settings are saved. When you next open Visual Studio, the connection to
the MySQL server will appear within Server Explorer so that you can
re-establish a connection to the MySQL server.

To modify and delete a connection, use the `Server Explorer' context
menu for the corresponding node. You can modify any of the settings
just by overwriting the existing values with new ones. Note that a
connection should be modified or deleted only if no active editor for
it's objects is opened.  Otherwise your data could be lost.


File: manual.info,  Node: connector-vstudio-using,  Next: connector-vstudio-support,  Prev: connector-vstudio-creating,  Up: connector-vstudio

30.3.3 Using the MySQL Visual Studio Plugin
-------------------------------------------

* Menu:

* connector-vstudio-using-tables::  Editing Tables
* connector-vstudio-using-tabledata::  Editing Table Data
* connector-vstudio-using-views::  Editing Views
* connector-vstudio-using-storedroutines::  Editing Stored Procedures and Functions
* connector-vstudio-using-triggers::  Editing Triggers
* connector-vstudio-using-udf::  Editing User Defined Functions (UDF)
* connector-vstudio-using-dropping::  Dropping database objects
* connector-vstudio-using-cloning::  Cloning database objects

To work with a MySQL server using the MySQL Visual Studio Plugin, open
the Visual Studio 2005, open the `Server Explorer', and select the
required connection. The working area of the MySQL Visual Studio Plugin
consists of three parts.

DDEX enviroment

   * Database objects (tables, views, stored routines, triggers, and
     user defined functions) are displayed in the Server Explorer tree.
     Here you can choose an object and edit its properties and
     definition.

   * Properties of a selected database object are displayed in the
     `Properties' panel. Certain properties can be edited directly
     within this window.

   * The editor panel provides direct access to the SQL statement and
     definition of specific objects. Fore example, the SQL statements
     within a stored procedure definition are shown and edited within
     this panel.


File: manual.info,  Node: connector-vstudio-using-tables,  Next: connector-vstudio-using-tabledata,  Prev: connector-vstudio-using,  Up: connector-vstudio-using

30.3.3.1 Editing Tables
.......................

* Menu:

* connector-vstudio-using-tables-columns::  Column Editor
* connector-vstudio-using-tables-indexes::  Indexes tab
* connector-vstudio-using-tables-foreignkeys::  Foreign Keys tab
* connector-vstudio-using-tables-column::  Column Details tab
* connector-vstudio-using-tables-properties::  Table Properties window

The Table Editor can be accessed through a mouse action on table-type
node of Server Explorer. To create a new table, right click on the
`Tables' node (under the connection node) and choose the `Create Table'
command from a context menu. To modify an existing table, double click
on a node of the table you wish to modify, or right click on this node
and choose the `Alter Table' command from a context menu. Either of the
commands opens the Table Editor.

Editing a table

The MySQL Visual Studio Plugin Table Editor is implemented in a similar
fashion to the standard Query Browser Table Editor, but with minor
differences.

The Table Editor consists of the following parts:

   * Columns Editor -- for column creation, modification and deletion.

   * Indexes tab -- for table/column index management.

   * Foreign Keys tab -- for configuration of foreign keys.

   * Column Details tab -- used to set advanced column options.

   * Properties window -- used to set table properties.

To save changes you have made in the Table Editor, use either Save or
Save All buttons of the Visual Studio main toolbar, or just press
`Ctrl+S'. Before changes are saved, a confirmation dialog will be
displayed to confirm that you want to update the corresponding object
within the MySQL database.


File: manual.info,  Node: connector-vstudio-using-tables-columns,  Next: connector-vstudio-using-tables-indexes,  Prev: connector-vstudio-using-tables,  Up: connector-vstudio-using-tables

30.3.3.2 Column Editor
......................

You can use the Column Editor to set or change the name, data type,
default value and other properties of a table column. To set the
properties of an individual column, select the column using the mouse.
Alternatively, you can move through the grid using `Tab' and `Shift+Tab'
keys.

   * To set or change the name, data type, default value and comment of
     a column, select the appropriate cell and edit the desired value.

   * To set or unset flag-type column properties (i.e., primary key,
     `NOT NULL', auto-incremented, flags), check or uncheck the
     corresponding checkboxes.  Note that the available column flags
     will depend on the columns data type.

   * To reorder columns, index columns or foreign key columns in the
     Column Editor, select the whole column you wish to reorder by
     clicking on the selector column at the left of the column grid.
     Then move the column by using `Ctrl+Up' (to move the column up) and
     `Ctrl+Down' (to move the column down) keys.

   * To delete a column, select it by clicking on the selector column
     at the left of the column grid, then press the `Delete' button on
     a keyboard.


File: manual.info,  Node: connector-vstudio-using-tables-indexes,  Next: connector-vstudio-using-tables-foreignkeys,  Prev: connector-vstudio-using-tables-columns,  Up: connector-vstudio-using-tables

30.3.3.3 Indexes tab
....................

Index management is performed via the Indexes tab.

   * To add an index, press the `+' button and set the properties in
     the `Index Settings' groupbox at the right. You can set the index
     name, index kind, index type and a set of index columns.

   * To remove an index, select the index from the list and press the
     `-' button.

   * To change index settings, select the index from the list; detailed
     information about the index is displayed in the `Index Settings'
     panel.

You cannot change a table column to an index column using drag and
drop. Instead, you can add new index columns to a table and set their
table columns by using the embedded editor within the Indexes tab


File: manual.info,  Node: connector-vstudio-using-tables-foreignkeys,  Next: connector-vstudio-using-tables-column,  Prev: connector-vstudio-using-tables-indexes,  Up: connector-vstudio-using-tables

30.3.3.4 Foreign Keys tab
.........................

Foreign Key management is performed via the Foreign Keys tab.

   * To add a foreign key, press the `+' button and set properties in
     the `Foreign Keys Settings' panel. You can set the foreign key
     name, referenced table name, foreign key columns and actions on
     update and delete.

   * To remove a foreign key, select the foreign key and press the `-'
     button.

   * To change foreign key settings, select the foreign key and use the
     `Foreign Keys Settings' panel to edit the properties.

   * When a foreign key is changed, the MySQL Visual Studio Plugin
     generates two queries: the first query drops the changed keys and
     the second one recreates the new values.  The reason for such a
     behavior is to avoid the Bug#8377 (http://bugs.mysql.com/8377) and
     Bug#8919 (http://bugs.mysql.com/8919).

*Note*:

If changed values are for some reason inconsistent and cause the second
query to fail, all affected foreign keys will be dropped. If this is
the case, the MySQL Visual Studio Plugin will mark them as new in the
Table Editor, and you will have to recreate them later. But if you
close the Table Editor without saving, these foreign keys will be lost.


File: manual.info,  Node: connector-vstudio-using-tables-column,  Next: connector-vstudio-using-tables-properties,  Prev: connector-vstudio-using-tables-foreignkeys,  Up: connector-vstudio-using-tables

30.3.3.5 Column Details tab
...........................

The Column Details tab can be used to set column options.  Besides the
main column properties that are presented in the Column Editor, in the
Column Details tab you can set two additional properties options: the
character set and the collation sequence.


File: manual.info,  Node: connector-vstudio-using-tables-properties,  Prev: connector-vstudio-using-tables-column,  Up: connector-vstudio-using-tables

30.3.3.6 Table Properties window
................................

There is no separate tab for table options and advanced options. All
table options can be browsed and changed using the `Properties' window
of Visual Studio 2005.

The following table properties can be set:

   * ` Auto Increment'

   * ` Average Row Length'

   * ` Character Set'

   * ` Checksum for Rows'

   * ` Collation'

   * ` Comment'

   * ` Connection'

   * ` Data Directory'

   * ` Delay Key Updates'

   * ` Engine'

   * ` Index Directory'

   * ` Insert Method'

   * ` Maximum Rows'

   * ` Minimum Rows'

   * ` Name'

   * ` Pack Keys'

   * ` Password'

   * `Row Format'

   * `Union'

Some of these properties can have arbitrary text values, others accept
values from a predefined set.

The properties `Schema' and `Server' are read only.


File: manual.info,  Node: connector-vstudio-using-tabledata,  Next: connector-vstudio-using-views,  Prev: connector-vstudio-using-tables,  Up: connector-vstudio-using

30.3.3.7 Editing Table Data
...........................

The Table Data Editor, allows a user to browse, create and edit data of
tables. The Table Data Editor is implemented as a simple data grid with
auto generated columns.

To access the Table Data Editor, right click on a node representing the
table or view in Server Explorer. From the nodes context menu, choose
the `Browse' or `Edit Data' command. For tables and updatable views,
this command opens the Table Data Editor in edit mode.  For
non-updatable views, this command opens the Table Data Editor in
read-only mode.

When in the edit mode, you can modify table data by modifying the
displayed table contents directly. To add a row, set desired values in
the last row of the grid. To modify values, set new values in
appropriate cells. To delete a row, select it by clicking on the
selector column at the left of the grid, then press the `Delete' button.

To save changes you have made in the Table Data Editor, use either
`Save' or `Save All' buttons of the Visual Studio main toolbar, or just
press `Ctrl+S'. A confirmation dialog will confirm whether you want the
changes saved to the database.


File: manual.info,  Node: connector-vstudio-using-views,  Next: connector-vstudio-using-storedroutines,  Prev: connector-vstudio-using-tabledata,  Up: connector-vstudio-using

30.3.3.8 Editing Views
......................

To create a new view, right click the Views node under the connection
node in Server Explorer. From the nodes context menu, choose the
`Create View' command. This command opens the SQL Editor.

To modify an existing view, double click on a node of the view you wish
to modify, or right click on this node and choose the `Alter View'
command from a context menu.  Either of the commands opens the SQL
Editor.

To create or alter the view definition using SQL Editor, type the
appropriate SQL statement in the SQL Editor.

*Note*:

You should enter only the defining statement itself, without the `
CREATE VIEW AS' preface.

All other view properties can be set in the `Properties' window. These
properties are:

   * `Algorithm'

   * ` Check Option'

   * `Definer'

   * `Name'

   * `Security Type'

Some of these properties can have arbitrary text values, others accept
values from a predefined set.

The properties `Is Updatable', `Schema' and `Server' are readonly.

To save changes you have made, use either `Save' or `Save All' buttons
of the Visual Studio main toolbar, or just press `Ctrl+S'. A
confirmation dialog will confirm whether you want the changes saved to
the database.


File: manual.info,  Node: connector-vstudio-using-storedroutines,  Next: connector-vstudio-using-triggers,  Prev: connector-vstudio-using-views,  Up: connector-vstudio-using

30.3.3.9 Editing Stored Procedures and Functions
................................................

To create a new stored procedure, right click the Stored Procedures
node under the connection node in Server Explorer.  From the nodes
context menu, choose the `Create Routine' command. This command opens
the SQL Editor.

To create a new stored function, right click the `Functions' node under
the connection node in Server Explorer. From the node's context menu,
choose the `Create Routine' command.

To modify an existing stored routine (procedure or function), double
click on a node of the routine you wish to modify, or right click on
this node and choose the `Alter Routine 'command from a context menu.
Either of the commands opens the SQL Editor.

To create or alter the routine definition using SQL Editor, type this
definition in the SQL Editor using standard SQL.

All other routine properties can be set in the `Properties' window.
These properties are:

   * Comment

   * Data Access

   * Definer

   * Is Deterministic

   * Security Type

Some of these properties can have arbitrary text values, others accept
values only from a predefined set.

Also you can set all the options directly in the SQL Editor, using the
standard `CREATE PROCEDURE' or `CREATE FUNCTION' statement. However, it
is recommended to use the `Properties' window instead.

*Note*:

You should never add the `CREATE' preface to the routine definition.

The properties `Name', `Schema' and `Server' in the `Properties' window
are read-only. Set or change the procedure name in the SQL editor.

To save changes you have made, use either `Save' or `Save All' buttons
of the Visual Studio main toolbar, or just press `Ctrl+S'. A
confirmation dialog will confirm whether you want the changes saved to
the database..


File: manual.info,  Node: connector-vstudio-using-triggers,  Next: connector-vstudio-using-udf,  Prev: connector-vstudio-using-storedroutines,  Up: connector-vstudio-using

30.3.3.10 Editing Triggers
..........................

To create a new trigger, right click on a node of a table for which you
wish to add a trigger. From the node's context menu, choose the `Create
Trigger' command. This command opens the SQL Editor.

To modify an existing trigger, double click on a node of the trigger
you wish to modify, or right click on this node and choose the `Alter
Trigger' command from a context menu. Either of the commands opens the
SQL Editor.

To create or alter the trigger definition using SQL Editor, type the
trigger statement in the SQL Editor using standard SQL.

*Note*:

You should enter only the trigger statement, that is the part of the
`CREATE TRIGGER' query that is placed after the `FOR EACH ROW' clause.

All other trigger properties are set in the `Properties' window. These
properties are:

   * `Definer'

   * `Event Manipulation'

   * `Name'

   * `Timing'

Some of these properties can have arbitrary text values, others accept
values only from a predefined set.

The properties `Event Table', `Schema' and `Server' in the `Properties'
window are read-only.

To save changes you have made, use either `Save' or `Save All' buttons
of the Visual Studio main toolbar, or just press `Ctrl+S'. A
confirmation dialog will confirm whether you want the changes saved to
the database.


File: manual.info,  Node: connector-vstudio-using-udf,  Next: connector-vstudio-using-dropping,  Prev: connector-vstudio-using-triggers,  Up: connector-vstudio-using

30.3.3.11 Editing User Defined Functions (UDF)
..............................................

To create a new User Defined Function (UDF), right click the UDFs node
under the connection node in Server Explorer. From the node's context
menu, choose the `Create UDF' command. This command opens the UDF
Editor.

To modify an existing UDF, double click on a node of the UDF you wish
to modify, or right click on this node and choose the Alter UDF command
from a context menu. Either of the commands opens the UDF Editor.

The UDF editor allows you to set the following properties through the
properties panel:

   * `Name'

   * `So-name (DLL name)'

   * `Return type'

   * `Is Aggregate'

The property Server in the `Properties' window is read-only.

To save changes you have made, use either `Save' or `Save All' buttons
of the Visual Studio main toolbar, or just press `Ctrl+S'. A
confirmation dialog will confirm whether you want the changes saved to
the database.


File: manual.info,  Node: connector-vstudio-using-dropping,  Next: connector-vstudio-using-cloning,  Prev: connector-vstudio-using-udf,  Up: connector-vstudio-using

30.3.3.12 Dropping database objects
...................................

Tables, views, stored routines, triggers, an UDFs can be dropped with
the appropriate `Drop' command from its context menu: `Drop Table',
`Drop View', `Drop Routine', `Drop Trigger', `Drop UDF'.

You will be asked to confirm the execution of the corresponding drop
query in a confirmation dialog.

Dropping of multiple objects is not supported.


File: manual.info,  Node: connector-vstudio-using-cloning,  Prev: connector-vstudio-using-dropping,  Up: connector-vstudio-using

30.3.3.13 Cloning database objects
..................................

Tables, views, stored procedures and functions can be cloned with the
appropriate `Clone' command from its context menu: `Clone Table', `Clone
View', `Clone Routine'. The clone commands open the corresponding
editor for a new object: the `Table Editor 'for cloning a table and the
SQL Editor for cloning a view or a routine.

To save the cloned object, use either `Save' or `Save All' buttons of
the Visual Studio main toolbar, or just press `Ctrl+S'. A confirmation
dialog will confirm whether you want the changes saved to the database.


File: manual.info,  Node: connector-vstudio-support,  Prev: connector-vstudio-using,  Up: connector-vstudio

30.3.4 Visual Studio Plugin Support
-----------------------------------

* Menu:

* connector-vstudio-faq::        Visual Studio Plugin FAQ

If you have a comment, or if you discover a bug, please, use our MySQL
bug tracking system (http://bugs.mysql.com (http://bugs.mysql.com)) to
report problem or add your suggestion.


File: manual.info,  Node: connector-vstudio-faq,  Prev: connector-vstudio-support,  Up: connector-vstudio-support

30.3.4.1 Visual Studio Plugin FAQ
.................................

*Questions*
   * 31.3.4.1.1: When creating a connection, typing the connection
     details causes the connection window to immediately close.

*Questions and Answers* *31.3.4.1.1: ** When creating a connection,
typing the connection details causes the connection window to
immediately close.  *

There are known issues with versions of Connector/NET earlier than
5.0.2. Connector/NET 1.0.x is known not to work. If you have any of
these versions installed, or have previously upgraded from an earlier
version, uninstall Connector/NET completely and then install
Connector/NET 5.0.2.


File: manual.info,  Node: connector-j,  Next: connector-mxj,  Prev: connector-vstudio,  Up: connectors

30.4 MySQL Connector/J
======================

* Menu:

* connector-j-versions::         Connector/J Versions
* connector-j-installing::       Connector/J Installation
* connector-j-examples::         Connector/J Examples
* connector-j-reference::        Connector/J (JDBC) Reference
* connector-j-usagenotes::       Connector/J Notes and Tips
* connector-j-support::          Connector/J Support

MySQL provides connectivity for client applications developed in the
Java programming language via a JDBC driver, which is called MySQL
Connector/J.

MySQL Connector/J is a JDBC Type 4 driver. Different versions are
available that are compatible with the JDBC 3.0 and JDBC 4.0
specifications. The Type 4 designation means that the driver is
pure-Java implementation of the MySQL protocol and does not rely on the
MySQL client libraries.

Although JDBC is useful by itself, we would hope that if you are not
familiar with JDBC that after reading the first few sections of this
manual, that you would avoid using naked JDBC for all but the most
trivial problems and consider using one of the popular persistence
frameworks such as Hibernate (http://www.hibernate.org/), Spring's JDBC
templates (http://www.springframework.org/) or Ibatis SQL Maps
(http://ibatis.apache.org/) to do the majority of repetitive work and
heavier lifting that is sometimes required with JDBC.

This section is not designed to be a complete JDBC tutorial. If you
need more information about using JDBC you might be interested in the
following online tutorials that are more in-depth than the information
presented here:

   * JDBC Basics
     (http://java.sun.com/docs/books/tutorial/jdbc/basics/index.html)
     -- A tutorial from Sun covering beginner topics in JDBC

   * JDBC Short Course
     (http://java.sun.com/developer/onlineTraining/Database/JDBCShortCourse/index.html)
     -- A more in-depth tutorial from Sun and JGuru

*Key topics:*

   * For help with connection strings, connection options setting up
     your connection through JDBC, see *Note
     connector-j-reference-configuration-properties::.

   * For tips on using Connector/J and JDBC with generic J2EE toolkits,
     see *Note connector-j-usagenotes-j2ee::.

   * Developers using the Tomcat server platform, see *Note
     connector-j-usagenotes-tomcat::.

   * Developers using JBoss, see *Note connector-j-usagenotes-jboss::.

   * Developers using Spring, see *Note
     connector-j-usagenotes-spring-config::.

MySQL Enterprise

MySQL Enterprise subscribers will find more information about using
JDBC with MySQL in the Knowledge Base articles about JDBC
(https://kb.mysql.com/search.php?cat=search&category=10). Access to the
MySQL Knowledge Base collection of articles is one of the advantages of
subscribing to MySQL Enterprise. For more information see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: connector-j-versions,  Next: connector-j-installing,  Prev: connector-j,  Up: connector-j

30.4.1 Connector/J Versions
---------------------------

* Menu:

* connector-j-versions-java::    Java Versions Supported

There are currently four versions of MySQL Connector/J available:

   * Connector/J 5.1 is the Type 4 pure Java JDBC driver, which
     conforms to the JDBC 3.0 and JDBC 4.0 specifications. It provides
     compatibility with all the functionality of MySQL, including 4.1,
     5.0, 5.1 and the 6.0 alpha release featuring the new Falcon
     storage engine. Connector/J 5.1 provides ease of development
     features, including auto-registration with the Driver Manager,
     standardized validity checks, categorized SQLExceptions, support
     for the JDBC-4.0 XML processing, per connection client
     information, `NCHAR', `NVARCHAR' and `NCLOB' types. This release
     also includes all bug fixes up to and including Connector/J 5.0.6.

   * Connector/J 5.0 provides support for all the functionality offered
     by Connector/J 3.1 and includes distributed transaction (XA)
     support.

   * Connector/J 3.1 was designed for connectivity to MySQL 4.1 and
     MySQL 5.0 servers and provides support for all the functionality
     in MySQL 5.0 except distributed transaction (XA) support.

   * Connector/J 3.0 provides core functionality and was designed with
     connectivity to MySQL 3.x or MySQL 4.1 servers, although it will
     provide basic compatibility with later versions of MySQL.
     Connector/J 3.0 does not support server-side prepared statements,
     and does not support any of the features in versions of MySQL
     later than 4.1.

The following table summarizes the Connector/J versions available:

*Connector/J   *Driver Type*  *JDBC version* *MySQL Server  *Status*
version*                                     version*       
5.1            4              3.0, 4.0       4.1, 5.0,      Recommended
                                             5.1, 6.0       version
5.0            4              3.0            4.1, 5.0       Released
                                                            version
3.1            4              3.0            4.1, 5.0       Obsolete
3.0            4              3.0            3.x, 4.1       Obsolete

The current recommended version for Connector/J is 5.1. This guide
covers all four connector versions, with specific notes given where a
setting applies to a specific option.


File: manual.info,  Node: connector-j-versions-java,  Prev: connector-j-versions,  Up: connector-j-versions

30.4.1.1 Java Versions Supported
................................

The following table summarizes Connector/J Java dependencies:

*Connector/J version*  *Java RTE required*    *JDK required (to
                                              build source code)*
5.1                    1.3.x, 1.4.x, 1.5.x,   1.6.x and 1.5.x (or
                       1.6.x                  older)
5.0                    1.3.x, 1.4.x, 1.5.x,   1.4.2, 1.5.x, 1.6.x
                       1.6.x                  
3.1                    1.2.x, 1.3.x, 1.4.x,   1.4.2, 1.5.x, 1.6.x
                       1.5.x, 1.6.x           
3.0                    1.2.x, 1.3.x, 1.4.x,   1.4.2, 1.5.x, 1.6.x
                       1.5.x, 1.6.x           

MySQL Connector/J does not support JDK-1.1.x or JDK-1.0.x.

Because of the implementation of java.sql.Savepoint, Connector/J 3.1.0
and newer will not run on a Java runtime older than 1.4 unless the
class verifier is turned off (by setting the `-Xverify:none' option to
the Java runtime). This is because the class verifier will try to load
the class definition for java.sql.Savepoint even though it is not
accessed by the driver unless you actually use savepoint functionality.

Caching functionality provided by Connector/J 3.1.0 or newer is also
not available on JVMs older than 1.4.x, as it relies on
java.util.LinkedHashMap which was first available in JDK-1.4.0.

If you are building Connector/J from source code using the source
distribution (see *Note connector-j-installing-source::) then you must
use JDK 1.4.2 or newer to compile the Connector package. For
Connector/J 5.1 you must have both JDK-1.6.x. and JDK-1.5.x installed
in order to be able to build the source code.


File: manual.info,  Node: connector-j-installing,  Next: connector-j-examples,  Prev: connector-j-versions,  Up: connector-j

30.4.2 Connector/J Installation
-------------------------------

* Menu:

* connector-j-installing-binary::  Installing Connector/J from a Binary Distribution
* connector-j-installing-classpath::  Installing the Driver and Configuring the `CLASSPATH'
* connector-j-installing-upgrading::  Upgrading from an Older Version
* connector-j-installing-source::  Installing from the Development Source Tree

You can install the Connector/J package using either the binary or
source distribution. The binary distribution provides the easiest
method for installation; the source distribution enables you to
customize your installation further. With either solution, you must
manually add the Connector/J location to your Java `CLASSPATH'.

If you are upgrading from a previous version, read the upgrade
information before continuing. See *Note
connector-j-installing-upgrading::.


File: manual.info,  Node: connector-j-installing-binary,  Next: connector-j-installing-classpath,  Prev: connector-j-installing,  Up: connector-j-installing

30.4.2.1 Installing Connector/J from a Binary Distribution
..........................................................

The easiest method of installation is to use the binary distribution of
the Connector/J package. The binary distribution is available either as
a Tar/Gzip or Zip file which you must extract to a suitable location
and then optionally make the information about the package available by
changing your `CLASSPATH' (see *Note
connector-j-installing-classpath::).

MySQL Connector/J is distributed as a .zip or .tar.gz archive
containing the sources, the class files, and the JAR archive named
`mysql-connector-java-[VERSION]-bin.jar', and starting with Connector/J
3.1.8 a debug build of the driver in a file named
`mysql-connector-java-[VERSION]-bin-g.jar'.

Starting with Connector/J 3.1.9, the `.class' files that constitute the
JAR files are only included as part of the driver JAR file.

You should not use the debug build of the driver unless instructed to
do so when reporting a problem or a bug to MySQL AB, as it is not
designed to be run in production environments, and will have adverse
performance impact when used. The debug binary also depends on the
Aspect/J runtime library, which is located in the
`src/lib/aspectjrt.jar' file that comes with the Connector/J
distribution.

You will need to use the appropriate graphical or command-line utility
to extract the distribution (for example, WinZip for the .zip archive,
and `tar' for the .tar.gz archive). Because there are potentially long
filenames in the distribution, we use the GNU tar archive format. You
will need to use GNU tar (or an application that understands the GNU tar
archive format) to unpack the .tar.gz variant of the distribution.


File: manual.info,  Node: connector-j-installing-classpath,  Next: connector-j-installing-upgrading,  Prev: connector-j-installing-binary,  Up: connector-j-installing

30.4.2.2 Installing the Driver and Configuring the `CLASSPATH'
..............................................................

Once you have extracted the distribution archive, you can install the
driver by placing `mysql-connector-java-[version]-bin.jar 'in your
classpath, either by adding the full path to it to your `CLASSPATH'
environment variable, or by directly specifying it with the command
line switch -cp when starting your JVM.

If you are going to use the driver with the JDBC DriverManager, you
would use `com.mysql.jdbc.Driver' as the class that implements
java.sql.Driver.

You can set the `CLASSPATH' environment variable under UNIX, Linux or
Mac OS X either locally for a user within their `.profile', `.login' or
other login file. You can also set it globally by editing the global
`/etc/profile' file.

For example, under a C shell (csh, tcsh) you would add the Connector/J
driver to your `CLASSPATH' using the following:

     shell> setenv CLASSPATH /path/mysql-connector-java-[ver]-bin.jar:$CLASSPATH

Or with a Bourne-compatible shell (sh, ksh, bash):

     shell> export set CLASSPATH=/path/mysql-connector-java-[ver]-bin.jar:$CLASSPATH

Within Windows 2000, Windows XP, Windows Server 2003 and Windows Vista,
you must set the environment variable through the System Control Panel.

If you want to use MySQL Connector/J with an application server such as
GlassFish, Tomcat or JBoss, you will have to read your vendor's
documentation for more information on how to configure third-party
class libraries, as most application servers ignore the `CLASSPATH'
environment variable. For configuration examples for some J2EE
application servers, see *Note connector-j-usagenotes-j2ee::. However,
the authoritative source for JDBC connection pool configuration
information for your particular application server is the documentation
for that application server.

If you are developing servlets or JSPs, and your application server is
J2EE-compliant, you can put the driver's .jar file in the WEB-INF/lib
subdirectory of your webapp, as this is a standard location for third
party class libraries in J2EE web applications.

You can also use the MysqlDataSource or MysqlConnectionPoolDataSource
classes in the `com.mysql.jdbc.jdbc2.optional' package, if your J2EE
application server supports or requires them. Starting with Connector/J
5.0.0, the `javax.sql.XADataSource' interface is implemented via the
`com.mysql.jdbc.jdbc2.optional.MysqlXADataSource' class, which supports
XA distributed transactions when used in combination with MySQL server
version 5.0.

The various MysqlDataSource classes support the following parameters
(through standard set mutators):

   * user

   * password

   * serverName (see the previous section about fail-over hosts)

   * databaseName

   * port


File: manual.info,  Node: connector-j-installing-upgrading,  Next: connector-j-installing-source,  Prev: connector-j-installing-classpath,  Up: connector-j-installing

30.4.2.3 Upgrading from an Older Version
........................................

* Menu:

* connector-j-installing-upgrading-3-0-to-3-1::  Upgrading from MySQL Connector/J 3.0 to 3.1
* connector-j-installing-upgrading-5-1::  Upgrading to MySQL Connector/J 5.1.x
* connector-j-installing-upgrading-issues::  JDBC-Specific Issues When Upgrading to MySQL Server 4.1 or Newer

MySQL AB tries to keep the upgrade process as easy as possible, however
as is the case with any software, sometimes changes need to be made in
new versions to support new features, improve existing functionality,
or comply with new standards.

This section has information about what users who are upgrading from
one version of Connector/J to another (or to a new version of the MySQL
server, with respect to JDBC functionality) should be aware of.


File: manual.info,  Node: connector-j-installing-upgrading-3-0-to-3-1,  Next: connector-j-installing-upgrading-5-1,  Prev: connector-j-installing-upgrading,  Up: connector-j-installing-upgrading

30.4.2.4 Upgrading from MySQL Connector/J 3.0 to 3.1
....................................................

Connector/J 3.1 is designed to be backward-compatible with Connector/J
3.0 as much as possible. Major changes are isolated to new
functionality exposed in MySQL-4.1 and newer, which includes Unicode
character sets, server-side prepared statements, SQLState codes
returned in error messages by the server and various performance
enhancements that can be enabled or disabled via configuration
properties.

   * *Unicode Character Sets* -- See the next section, as well as *Note
     charset::, for information on this new feature of MySQL. If you
     have something misconfigured, it will usually show up as an error
     with a message similar to `Illegal mix of collations'.

   * *Server-side Prepared Statements* -- Connector/J 3.1 will
     automatically detect and use server-side prepared statements when
     they are available (MySQL server version 4.1.0 and newer).

     Starting with version 3.1.7, the driver scans SQL you are
     preparing via all variants of `Connection.prepareStatement()' to
     determine if it is a supported type of statement to prepare on the
     server side, and if it is not supported by the server, it instead
     prepares it as a client-side emulated prepared statement. You can
     disable this feature by passing emulateUnsupportedPstmts=false in
     your JDBC URL.

     If your application encounters issues with server-side prepared
     statements, you can revert to the older client-side emulated
     prepared statement code that is still presently used for MySQL
     servers older than 4.1.0 with the connection property
     useServerPrepStmts=false

   * *Datetimes* with all-zero components (`0000-00-00 ...') -- These
     values can not be represented reliably in Java.  Connector/J 3.0.x
     always converted them to NULL when being read from a ResultSet.

     Connector/J 3.1 throws an exception by default when these values
     are encountered as this is the most correct behavior according to
     the JDBC and SQL standards. This behavior can be modified using the
     zeroDateTimeBehavior configuration property. The allowable values
     are:

        * `exception' (the default), which throws an SQLException with
          an SQLState of `S1009'.

        * `convertToNull', which returns `NULL' instead of the date.

        * `round', which rounds the date to the nearest closest value
          which is `0001-01-01'.

     Starting with Connector/J 3.1.7, `ResultSet.getString()' can be
     decoupled from this behavior via noDatetimeStringSync=true (the
     default value is `false') so that you can retrieve the unaltered
     all-zero value as a String. It should be noted that this also
     precludes using any time zone conversions, therefore the driver
     will not allow you to enable noDatetimeStringSync and useTimezone
     at the same time.

   * *New SQLState Codes* -- Connector/J 3.1 uses SQL:1999 SQLState
     codes returned by the MySQL server (if supported), which are
     different from the legacy X/Open state codes that Connector/J 3.0
     uses. If connected to a MySQL server older than MySQL-4.1.0 (the
     oldest version to return SQLStates as part of the error code), the
     driver will use a built-in mapping. You can revert to the old
     mapping by using the configuration property useSqlStateCodes=false.

   * *`ResultSet.getString()'* -- Calling `ResultSet.getString()' on a
     BLOB column will now return the address of the byte[] array that
     represents it, instead of a String representation of the BLOB.
     BLOBs have no character set, so they can't be converted to
     java.lang.Strings without data loss or corruption.

     To store strings in MySQL with LOB behavior, use one of the TEXT
     types, which the driver will treat as a java.sql.Clob.

   * *Debug builds* -- Starting with Connector/J 3.1.8 a debug build of
     the driver in a file named
     `mysql-connector-java-[VERSION]-bin-g.jar' is shipped alongside
     the normal binary jar file that is named
     `mysql-connector-java-[VERSION]-bin.jar'.

     Starting with Connector/J 3.1.9, we don't ship the .class files
     unbundled, they are only available in the JAR archives that ship
     with the driver.

     You should not use the debug build of the driver unless instructed
     to do so when reporting a problem or bug to MySQL AB, as it is not
     designed to be run in production environments, and will have
     adverse performance impact when used. The debug binary also
     depends on the Aspect/J runtime library, which is located in the
     `src/lib/aspectjrt.jar' file that comes with the Connector/J
     distribution.


File: manual.info,  Node: connector-j-installing-upgrading-5-1,  Next: connector-j-installing-upgrading-issues,  Prev: connector-j-installing-upgrading-3-0-to-3-1,  Up: connector-j-installing-upgrading

30.4.2.5 Upgrading to MySQL Connector/J 5.1.x
.............................................

   * In Connector/J 5.0.x and earlier, the alias for a table in a
     `SELECT' statement is returned when accessing the result set
     metadata using `ResultSetMetaData.getColumnName()'.  This behavior
     however is not JDBC compliant, and in Connector/J 5.1 this
     behavior was changed so that the original table name, rather than
     the alias, is returned.

     The JDBC-compliant behavior is designed to let API users
     reconstruct the DML statement based on the metadata within
     `ResultSet' and `ResultSetMetaData'.

     You can get the alias for a column in a result set by calling
     `ResultSetMetaData.getColumnLabel()'.  If you want to use the old
     non-compliant behavior with `ResultSetMetaData.getColumnName()',
     use the `useOldAliasMetadataBehavior' option and set the value to
     `true'.

     In Connector/J 5.0.x the default value of
     `useOldAliasMetadataBehavior' was true, but in Connector/J 5.1
     this was changed to a default value of false.


File: manual.info,  Node: connector-j-installing-upgrading-issues,  Prev: connector-j-installing-upgrading-5-1,  Up: connector-j-installing-upgrading

30.4.2.6 JDBC-Specific Issues When Upgrading to MySQL Server 4.1 or Newer
.........................................................................

   * _Using the UTF-8 Character Encoding_ - Prior to MySQL server
     version 4.1, the UTF-8 character encoding was not supported by the
     server, however the JDBC driver could use it, allowing storage of
     multiple character sets in latin1 tables on the server.

     Starting with MySQL-4.1, this functionality is deprecated.  If you
     have applications that rely on this functionality, and can not
     upgrade them to use the official Unicode character support in
     MySQL server version 4.1 or newer, you should add the following
     property to your connection URL:

     useOldUTF8Behavior=true

   * _Server-side Prepared Statements_ - Connector/J 3.1 will
     automatically detect and use server-side prepared statements when
     they are available (MySQL server version 4.1.0 and newer). If your
     application encounters issues with server-side prepared
     statements, you can revert to the older client-side emulated
     prepared statement code that is still presently used for MySQL
     servers older than 4.1.0 with the following connection property:

     useServerPrepStmts=false


File: manual.info,  Node: connector-j-installing-source,  Prev: connector-j-installing-upgrading,  Up: connector-j-installing

30.4.2.7 Installing from the Development Source Tree
....................................................

*Caution*:

You should read this section only if you are interested in helping us
test our new code. If you just want to get MySQL Connector/J up and
running on your system, you should use a standard binary release
distribution.

To install MySQL Connector/J from the development source tree, make
sure that you have the following prerequisites:

   * Subversion, to check out the sources from our repository
     (available from `http://subversion.tigris.org/').

   * Apache Ant version 1.7 or newer (available from
     `http://ant.apache.org/').

   * JDK 1.4.2 or later. Although MySQL Connector/J can be be used with
     older JDKs, to compile it from source you must have at least JDK
     1.4.2. If you are building Connector/J 5.1 you will need JDK 1.6.x
     and an older JDK such as JDK 1.5.x.  You will then need to point
     your JAVA_HOME environment variable at the older installation.

The Subversion source code repository for MySQL Connector/J is located
at `http://svn.mysql.com/svnpublic/connector-j'. In general, you should
not check out the entire repository because it contains every branch
and tag for MySQL Connector/J and is quite large.

To check out and compile a specific branch of MySQL Connector/J, follow
these steps:

  1. Check out the latest code from the branch that you want with the
     following command (replacing [MAJOR] and [MINOR] with appropriate
     version numbers):

          shell> svn co »
          http://svn.mysql.com/svnpublic/connector-j/branches/branch_[MAJOR]_[MINOR] connector-j

     This creates a `connector-j' subdirectory in the current directory
     that contains the latest sources for the requested branch.

  2. If you are building Connector/J 5.1 make sure that you have both
     JDK 1.6.x installed and an older JDK such as JDK 1.5.x.  This is
     because Connector/J supports both JDBC 3.0 (which was prior to JDK
     1.6.x) and JDBC 4.0. Set your JAVA_HOME environment variable to
     the path of the older JDK installation.

  3. Change location to the `connector-j' directory to make it your
     current working directory:

          shell> cd connector-j

  4. If you are building Connector/J 5.1 you need to edit the
     `build.xml' to reflect the location of your JDK 1.6.x
     installation. The lines that you need to change are:

                      <property name="com.mysql.jdbc.java6.javac" value="C:\jvms\jdk1.6.0\bin\javac.exe" />
                      <property name="com.mysql.jdbc.java6.rtjar" value="C:\jvms\jdk1.6.0\jre\lib\rt.jar" />

     Alternatively, you can set the value of these property names
     through the Ant `-D' option.

  5. Issue the following command to compile the driver and create a
     `.jar' file suitable for installation:

          shell> ant dist

     This creates a `build' directory in the current directory, where
     all build output will go. A directory is created in the `build'
     directory that includes the version number of the sources you are
     building from. This directory contains the sources, compiled
     `.class' files, and a `.jar' file suitable for deployment. For
     other possible targets, including ones that will create a fully
     packaged distribution, issue the following command:

          shell> ant -projecthelp

  6. A newly created `.jar' file containing the JDBC driver will be
     placed in the directory `build/mysql-connector-java-[VERSION]'.

     Install the newly created JDBC driver as you would a binary `.jar'
     file that you download from MySQL by following the instructions in
     *Note connector-j-installing-classpath::.

A package containing both the binary and source code for Connector/J
5.1 can also be found at the following location: Connector/J 5.1
Download (http://dev.mysql.com/downloads/connector/j/5.1.html)


File: manual.info,  Node: connector-j-examples,  Next: connector-j-reference,  Prev: connector-j-installing,  Up: connector-j

30.4.3 Connector/J Examples
---------------------------

Examples of using Connector/J are located throughout this document,
this section provides a summary and links to these examples.

   * *Note connector-j-examples-connection-drivermanager::

   * *Note connector-j-examples-execute-select::

   * *Note connector-j-examples-stored-procedure::

   * *Note connector-j-examples-preparecall::

   * *Note connector-j-examples-output-param::

   * *Note connector-j-examples-callablestatement::

   * *Note connector-j-examples-retrieving-results-params::

   * *Note connector-j-examples-autoincrement-getgeneratedkeys::

   * *Note connector-j-examples-autoincrement-select::

   * *Note connector-j-examples-autoincrement-updateable-resultsets::

   * *Note connector-j-examples-connectionpool-j2ee::

   * *Note connector-j-examples-transaction-retry::


File: manual.info,  Node: connector-j-reference,  Next: connector-j-usagenotes,  Prev: connector-j-examples,  Up: connector-j

30.4.4 Connector/J (JDBC) Reference
-----------------------------------

* Menu:

* connector-j-reference-configuration-properties::  Driver/Datasource Class Names, URL Syntax and Configuration Properties for Connector/J
* connector-j-reference-implementation-notes::  JDBC API Implementation Notes
* connector-j-reference-type-conversions::  Java, JDBC and MySQL Types
* connector-j-reference-charsets::  Using Character Sets and Unicode
* connector-j-reference-using-ssl::  Connecting Securely Using SSL
* connector-j-reference-replication-connection::  Using Master/Slave Replication with ReplicationConnection
* connector-j-reference-error-sqlstates::  Mapping MySQL Error Numbers to SQLStates

This section of the manual contains reference material for MySQL
Connector/J, some of which is automatically generated during the
Connector/J build process.


File: manual.info,  Node: connector-j-reference-configuration-properties,  Next: connector-j-reference-implementation-notes,  Prev: connector-j-reference,  Up: connector-j-reference

30.4.4.1 Driver/Datasource Class Names, URL Syntax and Configuration Properties for Connector/J
...............................................................................................

The name of the class that implements java.sql.Driver in MySQL
Connector/J is `com.mysql.jdbc.Driver'. The `org.gjt.mm.mysql.Driver'
class name is also usable to remain backward-compatible with MM.MySQL.
You should use this class name when registering the driver, or when
otherwise configuring software to use MySQL Connector/J.

The JDBC URL format for MySQL Connector/J is as follows, with items in
square brackets ([, ]) being optional:

     jdbc:mysql://[host][,failoverhost...][:port]/[database] »
     [?propertyName1][=propertyValue1][&propertyName2][=propertyValue2]...

If the hostname is not specified, it defaults to 127.0.0.1. If the port
is not specified, it defaults to 3306, the default port number for
MySQL servers.

     jdbc:mysql://[host:port],[host:port].../[database] »
     [?propertyName1][=propertyValue1][&propertyName2][=propertyValue2]...

If the database is not specified, the connection will be made with no
default database. In this case, you will need to either call the
`setCatalog()' method on the Connection instance or fully-specify table
names using the database name (i.e. `SELECT dbname.tablename.colname
FROM dbname.tablename...') in your SQL. Not specifying the database to
use upon connection is generally only useful when building tools that
work with multiple databases, such as GUI database managers.

MySQL Connector/J has fail-over support. This allows the driver to
fail-over to any number of slave hosts and still perform read-only
queries. Fail-over only happens when the connection is in an
`autoCommit(true)' state, because fail-over can not happen reliably
when a transaction is in progress. Most application servers and
connection pools set `autoCommit' to `true' at the end of every
transaction/connection use.

The fail-over functionality has the following behavior:

   * If the URL property autoReconnect is false: Failover only happens
     at connection initialization, and failback occurs when the driver
     determines that the first host has become available again.

   * If the URL property autoReconnect is true: Failover happens when
     the driver determines that the connection has failed (before
     _every_ query), and falls back to the first host when it determines
     that the host has become available again (after
     `queriesBeforeRetryMaster' queries have been issued).

In either case, whenever you are connected to a "failed-over" server,
the connection will be set to read-only state, so queries that would
modify data will have exceptions thrown (the query will *never* be
processed by the MySQL server).

Configuration properties define how Connector/J will make a connection
to a MySQL server. Unless otherwise noted, properties can be set for a
DataSource object or for a Connection object.

Configuration Properties can be set in one of the following ways:

   * Using the set*() methods on MySQL implementations of
     java.sql.DataSource (which is the preferred method when using
     implementations of java.sql.DataSource):

        * com.mysql.jdbc.jdbc2.optional.MysqlDataSource

        * com.mysql.jdbc.jdbc2.optional.MysqlConnectionPoolDataSource

   * As a key/value pair in the java.util.Properties instance passed to
     `DriverManager.getConnection()' or `Driver.connect()'

   * As a JDBC URL parameter in the URL given to
     `java.sql.DriverManager.getConnection()',
     `java.sql.Driver.connect()' or the MySQL implementations of the
     `javax.sql.DataSource' `setURL()' method.

     *Note*:

     If the mechanism you use to configure a JDBC URL is XML-based, you
     will need to use the XML character literal &amp; to separate
     configuration parameters, as the ampersand is a reserved character
     for XML.

The properties are listed in the following tables.

Connection/Authentication

* Property Name *      * Definition *                       *       *
                                                            Default Since
                                                            Value * Version
                                                                    *
user                   The user to connect as                       all
                                                                    versions
password               The password to use when connecting          all
                                                                    versions
socketFactory          The name of the class that the       com.mysql.jdbc.StandardSocketFactory3.0.3
                       driver should use for creating               
                       socket connections to the server.            
                       This class must implement the                
                       interface                                    
                       'com.mysql.jdbc.SocketFactory' and           
                       have public no-args constructor.             
connectTimeout         Timeout for socket connect (in       0       3.0.1
                       milliseconds), with 0 being no               
                       timeout.  Only works on JDK-1.4 or           
                       newer. Defaults to '0'.                      
socketTimeout          Timeout on network socket            0       3.0.1
                       operations (0, the default means no          
                       timeout).                                    
connectionLifecycleInterceptorsA comma-delimited list of classes            5.1.4
                       that implement                               
                       "com.mysql.jdbc.ConnectionLifecycleInterceptor"        
                       that should notified of connection           
                       lifecycle events (creation,                  
                       destruction, commit, rollback,               
                       setCatalog and setAutoCommit) and            
                       potentially alter the execution of           
                       these commands.                              
                       ConnectionLifecycleInterceptors are          
                       "stackable", more than one                   
                       interceptor may be specified via             
                       the configuration property as a              
                       comma-delimited list, with the               
                       interceptors executed in order from          
                       left to right.                               
useConfigs             Load the comma-delimited list of             3.1.5
                       configuration properties before              
                       parsing the URL or applying                  
                       user-specified properties. These             
                       configurations are explained in the          
                       'Configurations' of the                      
                       documentation.                               
interactiveClient      Set the CLIENT_INTERACTIVE flag,     false   3.1.0
                       which tells MySQL to timeout                 
                       connections based on                         
                       INTERACTIVE_TIMEOUT instead of               
                       WAIT_TIMEOUT                                 
localSocketAddress     Hostname or IP address given to              5.0.5
                       explicitly configure the interface           
                       that the driver will bind the                
                       client side of the TCP/IP                    
                       connection to when connecting.               
mysqlIOFactory         The name of the class which          com.mysql.jdbc.MysqlIOprotocol6.0.0
                       implements "com.mysql.jdbc.MysqlIO"          
                       for communicating with mysqld.               
                       (default is                                  
                       "com.mysql.jdbc.MysqlIOprotocol")            
propertiesTransform    An implementation of                         3.1.4
                       com.mysql.jdbc.ConnectionPropertiesTransform        
                       that the driver will use to modify           
                       URL properties passed to the driver          
                       before attempting a connection               
useCompression         Use zlib compression when            false   3.0.17
                       communicating with the server                
                       (true/false)?  Defaults to 'false'.          

Networking

* Property Name *      * Definition *                       *       *
                                                            Default Since
                                                            Value * Version
                                                                    *
tcpKeepAlive           If connecting using TCP/IP, should   true    5.0.7
                       the driver set SO_KEEPALIVE?                 
tcpNoDelay             If connecting using TCP/IP, should   true    5.0.7
                       the driver set SO_TCP_NODELAY                
                       (disabling the Nagle Algorithm)?             
tcpRcvBuf              If connecting using TCP/IP, should   0       5.0.7
                       the driver set SO_RCV_BUF to the             
                       given value? The default value of            
                       '0', means use the platform default          
                       value for this property)                     
tcpSndBuf              If connecting using TCP/IP, shuold   0       5.0.7
                       the driver set SO_SND_BUF to the             
                       given value? The default value of            
                       '0', means use the platform default          
                       value for this property)                     
tcpTrafficClass        If connecting using TCP/IP, should   0       5.0.7
                       the driver set traffic class or              
                       type-of-service fields ?See the              
                       documentation for                            
                       java.net.Socket.setTrafficClass()            
                       for more information.                        

High Availability and Clustering

* Property Name *      * Definition *                       *       *
                                                            Default Since
                                                            Value * Version
                                                                    *
autoReconnect          Should the driver try to             false   1.1
                       re-establish stale and/or dead               
                       connections? If enabled the driver           
                       will throw an exception for a                
                       queries issued on a stale or dead            
                       connection, which belong to the              
                       current transaction, but will                
                       attempt reconnect before the next            
                       query issued on the connection in a          
                       new transaction. The use of this             
                       feature is not recommended, because          
                       it has side effects related to               
                       session state and data consistency           
                       when applications don't handle               
                       SQLExceptions properly, and is only          
                       designed to be used when you are             
                       unable to configure your                     
                       application to handle SQLExceptions          
                       resulting from dead and stale                
                       connections properly.                        
                       Alternatively, investigate setting           
                       the MySQL server variable                    
                       "wait_timeout" to some high value            
                       rather than the default of 8 hours.          
autoReconnectForPools  Use a reconnection strategy          false   3.1.3
                       appropriate for connection pools             
                       (defaults to 'false')                        
failOverReadOnly       When failing over in autoReconnect   true    3.0.12
                       mode, should the connection be set           
                       to 'read-only'?                              
maxReconnects          Maximum number of reconnects to      3       1.1
                       attempt if autoReconnect is true,            
                       default is '3'.                              
reconnectAtTxEnd       If autoReconnect is set to true,     false   3.0.10
                       should the driver attempt                    
                       reconnections at the end of every            
                       transaction?                                 
initialTimeout         If autoReconnect is enabled, the     2       1.1
                       initial time to wait between                 
                       re-connect attempts (in seconds,             
                       defaults to '2').                            
roundRobinLoadBalance  When autoReconnect is enabled, and   false   3.1.2
                       failoverReadonly is false, should we         
                       pick hosts to connect to on a                
                       round-robin basis?                           
queriesBeforeRetryMasterNumber of queries to issue before    50      3.0.2
                       falling back to master when failed           
                       over (when using multi-host                  
                       failover). Whichever condition is            
                       met first,                                   
                       'queriesBeforeRetryMaster' or                
                       'secondsBeforeRetryMaster' will              
                       cause an attempt to be made to               
                       reconnect to the master. Defaults            
                       to 50.                                       
secondsBeforeRetryMasterHow long should the driver wait,     30      3.0.2
                       when failed over, before attempting          
selfDestructOnPingMaxOperations=If set to a non-zero value, the     0       5.1.6
                       driver will report close the                 
                       connection and report failure when           
                       Connection.ping() or                         
                       Connection.isValid(int) is called            
                       if the connnection's count of                
                       commands sent to the server exceeds          
                       this value.                                  
selfDestructOnPingSecondsLifetimeIf set to a non-zero value, the      0       5.1.6
                       driver will report close the                 
                       connection and report failure when           
                       Connection.ping() or                         
                       Connection.isValid(int) is called            
                       if the connnection's lifetime                
                       exceeds this value.                          
resourceId             A globally unique name that                  5.0.1
                       identifies the resource that this            
                       datasource or connection is                  
                       connected to, used for                       
                       XAResource.isSameRM() when the               
                       driver can't determine this value            
                       based on hostnames used in the URL           

Security

* Property Name *      * Definition *                       *       *
                                                            Default Since
                                                            Value * Version
                                                                    *
allowMultiQueries      Allow the use of ';' to delimit      false   3.1.1
                       multiple queries during one                  
                       statement (true/false), defaults to          
                       'false'                                      
useSSL                 Use SSL when communicating with the  false   3.0.2
                       server (true/false), defaults to             
                       'false'                                      
requireSSL             Require SSL connection if            false   3.1.0
                       useSSL=true? (defaults to 'false').          
verifyServerCertificateIf "useSSL" is set to "true",        true    5.1.6
                       should the driver verify the                 
                       server's certificate? When using             
                       this feature, the keystore                   
                       parameters should be specified by            
                       the "clientCertificateKeyStore*"             
                       properties, rather than system               
                       properties.                                  
clientCertificateKeyStoreUrlURL to the client certificate                5.1.0
                       KeyStore (if not specified, use              
                       defaults)                                    
clientCertificateKeyStoreTypeKeyStore type for client                     5.1.0
                       certificates (NULL or empty means            
                       use default, standard keystore               
                       types supported by the JVM are "JKS"         
                       and "PKCS12", your environment may           
                       have more available depending on             
                       what security products are                   
                       installed and available to the JVM.          
clientCertificateKeyStorePasswordPassword for the client                      5.1.0
                       certificates KeyStore                        
trustCertificateKeyStoreUrlURL to the trusted root certificate          5.1.0
                       KeyStore (if not specified, use              
                       defaults)                                    
trustCertificateKeyStoreTypeKeyStore type for trusted root               5.1.0
                       certificates (NULL or empty means            
                       use default, standard keystore               
                       types supported by the JVM are               
                       "JKS" and "PKCS12", your                     
                       environment may have more available          
                       depending on what security products          
                       are installed and available to the           
                       JVM.                                         
trustCertificateKeyStorePasswordPassword for the trusted root                5.1.0
                       certificates KeyStore                        
allowLoadLocalInfile   Should the driver allow use of       true    3.0.3
                       'LOAD DATA LOCAL INFILE...'                  
                       (defaults to 'true').                        
allowUrlInLocalInfile  Should the driver allow URLs in      false   3.1.4
                       'LOAD DATA LOCAL INFILE' statements?         
paranoid               Take measures to prevent exposure    false   3.0.1
                       sensitive information in error               
                       messages and clear data structures           
                       holding sensitive data when                  
                       possible? (defaults to 'false')              

Performance Extensions

* Property Name *      * Definition *                       *       *
                                                            Default Since
                                                            Value * Version
                                                                    *
callableStmtCacheSize  If 'cacheCallableStmts' is enabled,  100     3.1.2
                       how many callable statements should          
                       be cached?                                   
metadataCacheSize      The number of queries to cache       50      3.1.1
                       ResultSetMetadata for if                     
                       cacheResultSetMetaData is set to             
                       'true' (default 50)                          
prepStmtCacheSize      If prepared statement caching is     25      3.0.10
                       enabled, how many prepared                   
                       statements should be cached?                 
prepStmtCacheSqlLimit  If prepared statement caching is     256     3.0.10
                       enabled, what's the largest SQL the          
                       driver will cache the parsing for?           
alwaysSendSetIsolation Should the driver always             true    3.1.7
                       communicate with the database when           
                       Connection.setTransactionIsolation()         
                       is called? If set to false, the              
                       driver will only communicate with            
                       the database when the requested              
                       transaction isolation is different           
                       than the whichever is newer, the             
                       last value that was set via                  
                       Connection.setTransactionIsolation(),        
                       or the value that was read from the          
                       server when the connection was               
                       established.                                 
maintainTimeStats      Should the driver maintain various   true    3.1.9
                       internal timers to enable idle time          
                       calculations as well as more                 
                       verbose error messages when the              
                       connection to the server fails?              
                       Setting this property to false               
                       removes at least two calls to                
                       System.getCurrentTimeMillis() per            
                       query.                                       
useCursorFetch         If connected to MySQL > 5.0.2, and   false   5.0.0
                       setFetchSize() > 0 on a statement,           
                       should that statement use                    
                       cursor-based fetching to retrieve            
                       rows?                                        
blobSendChunkSize      Chunk to use when sending            1048576 3.1.9
                       BLOB/CLOBs via                               
                       ServerPreparedStatements                     
cacheCallableStmts     Should the driver cache the parsing  false   3.1.2
                       stage of CallableStatements                  
cachePrepStmts         Should the driver cache the parsing  false   3.0.10
                       stage of PreparedStatements of               
                       client-side prepared statements,             
                       the "check" for suitability of               
                       server-side prepared and server-side         
                       prepared statements themselves?              
cacheResultSetMetadata Should the driver cache              false   3.1.1
                       ResultSetMetaData for Statements and         
                       PreparedStatements? (Req. JDK-1.4+,          
                       true/false, default 'false')                 
cacheServerConfigurationShould the driver cache the results  false   3.1.5
                       of 'SHOW VARIABLES' and 'SHOW                
                       COLLATION' on a per-URL basis?               
defaultFetchSize       The driver will call                 0       3.1.9
                       setFetchSize(n) with this value on           
                       all newly-created Statements                 
dontTrackOpenResources The JDBC specification requires the  false   3.1.7
                       driver to automatically track and            
                       close resources, however if your             
                       application doesn't do a good job            
                       of explicitly calling close() on             
                       statements or result sets, this can          
                       cause memory leakage. Setting this           
                       property to true relaxes this                
                       constraint, and can be more memory           
                       efficient for some applications.             
dynamicCalendars       Should the driver retrieve the       false   3.1.5
                       default calendar when required, or           
                       cache it per connection/session?             
elideSetAutoCommits    If using MySQL-4.1 or newer, should  false   3.1.3
                       the driver only issue 'set                   
                       autocommit=n' queries when the               
                       server's state doesn't match the             
                       requested state by                           
                       Connection.setAutoCommit(boolean)?           
enableQueryTimeouts    When enabled, query timeouts set     true    5.0.6
                       via Statement.setQueryTimeout() use          
                       a shared java.util.Timer instance            
                       for scheduling. Even if the timeout          
                       doesn't expire before the query is           
                       processed, there will be memory              
                       used by the TimerTask for the given          
                       timeout which won't be reclaimed             
                       until the time the timeout would             
                       have expired if it hadn't been               
                       cancelled by the driver. High-load           
                       environments might want to consider          
                       disabling this functionality.                
holdResultsOpenOverStatementCloseShould the driver close result sets  false   3.1.7
                       on Statement.close() as required by          
                       the JDBC specification?                      
largeRowSizeThreshold  What size result set row should the  2048    5.1.1
                       JDBC driver consider "large", and            
                       thus use a more memory-efficient             
                       way of representing the row                  
                       internally?                                  
loadBalanceStrategy    If using a load-balanced connection  random  5.0.6
                       to connect to SQL nodes in a MySQL           
                       Cluster/NDB configuration (by using          
                       the URL prefix                               
                       "jdbc:mysql:loadbalance://"), which          
                       load balancing algorithm should the          
                       driver use: (1) "random" - the               
                       driver will pick a random host for           
                       each request. This tends to work             
                       better than round-robin, as the              
                       randomness will somewhat account             
                       for spreading loads where requests           
                       vary in response time, while                 
                       round-robin can sometimes lead to            
                       overloaded nodes if there are                
                       variations in response times across          
                       the workload. (2)                            
                       "bestResponseTime" - the driver              
                       will route the request to the host           
                       that had the best response time for          
                       the previous transaction.                    
locatorFetchBufferSize If 'emulateLocators' is configured   1048576 3.2.1
                       to 'true', what size buffer should           
                       be used when fetching BLOB data for          
                       getBinaryInputStream?                        
rewriteBatchedStatementsShould the driver use multiqueries   false   3.1.13
                       (irregardless of the setting of              
                       "allowMultiQueries") as well as              
                       rewriting of prepared statements             
                       for INSERT into multi-value inserts          
                       when executeBatch() is called?               
                       Notice that this has the potential           
                       for SQL injection if using plain             
                       java.sql.Statements and your code            
                       doesn't sanitize input correctly.            
                       Notice that for prepared statements,         
                       server-side prepared statements can          
                       not currently take advantage of              
                       this rewrite option, and that if             
                       you don't specify stream lengths             
                       when using                                   
                       PreparedStatement.set*Stream(), the          
                       driver won't be able to determine            
                       the optimum number of parameters             
                       per batch and you might receive an           
                       error from the driver that the               
                       resultant packet is too large.               
                       Statement.getGeneratedKeys() for             
                       these rewritten statements only              
                       works when the entire batch includes         
                       INSERT statements.                           
useDirectRowUnpack     Use newer result set row unpacking   true    5.1.1
                       code that skips a copy from network          
                       buffers to a MySQL packet instance           
                       and instead reads directly into the          
                       result set row data buffers.                 
useDynamicCharsetInfo  Should the driver use a              true    5.0.6
                       per-connection cache of character            
                       set information queried from the             
                       server when necessary, or use a              
                       built-in static mapping that is              
                       more efficient, but isn't aware of           
                       custom character sets or character           
                       sets implemented after the release           
                       of the JDBC driver?                          
useFastDateParsing     Use internal                         true    5.0.5
                       String->Date/Time/Timestamp                  
                       conversion routines to avoid                 
                       excessive object creation?                   
useFastIntParsing      Use internal String->Integer         true    3.1.4
                       conversion routines to avoid                 
                       excessive object creation?                   
useJvmCharsetConvertersAlways use the character encoding    false   5.0.1
                       routines built into the JVM, rather          
                       than using lookup tables for                 
                       single-byte character sets?                  
useLocalSessionState   Should the driver refer to the       false   3.1.7
                       internal values of autocommit and            
                       transaction isolation that are set           
                       by Connection.setAutoCommit() and            
                       Connection.setTransactionIsolation()         
                       and transaction state as maintained          
                       by the protocol, rather than                 
                       querying the database or blindly             
                       sending commands to the database             
                       for commit() or rollback() method            
                       calls?                                       
useReadAheadInput      Use newer, optimized non-blocking,   true    3.1.5
                       buffered input stream when reading           
                       from the server?                             

Debugging/Profiling

* Property Name *      * Definition *                       *       *
                                                            Default Since
                                                            Value * Version
                                                                    *
logger                 The name of a class that implements  com.mysql.jdbc.log.StandardLogger3.1.1
                       "com.mysql.jdbc.log.Log" that will           
                       be used to log messages to.                  
                       (default is                                  
                       "com.mysql.jdbc.log.StandardLogger",         
                       which logs to STDERR)                        
gatherPerfMetrics      Should the driver gather             false   3.1.2
                       performance metrics, and report              
                       them via the configured logger               
                       every 'reportMetricsIntervalMillis'          
                       milliseconds?                                
profileSQL             Trace queries and their              false   3.1.0
                       execution/fetch times to the                 
                       configured logger (true/false)               
                       defaults to 'false'                          
profileSql             Deprecated, use 'profileSQL'                 2.0.14
                       instead. Trace queries and their             
                       execution/fetch times on STDERR              
                       (true/false) defaults to 'false'             
reportMetricsIntervalMillisIf 'gatherPerfMetrics' is enabled,   30000   3.1.2
                       how often should they be logged (in          
                       ms)?                                         
maxQuerySizeToLog      Controls the maximum length/size of  2048    3.1.3
                       a query that will get logged when            
                       profiling or tracing                         
packetDebugBufferSize  The maximum number of packets to     20      3.1.3
                       retain when 'enablePacketDebug' is           
                       true                                         
slowQueryThresholdMillisIf 'logSlowQueries' is enabled, how  2000    3.1.2
                       long should a query (in ms) before           
                       it is logged as 'slow'?                      
slowQueryThresholdNanosIf 'useNanosForElapsedTime' is set   0       5.0.7
                       to true, and this property is set to         
                       a non-zero value, the driver will            
                       use this threshold (in nanosecond            
                       units) to determine if a query was           
                       slow.                                        
useUsageAdvisor        Should the driver issue 'usage'      false   3.1.1
                       warnings advising proper and                 
                       efficient usage of JDBC and MySQL            
                       Connector/J to the log (true/false,          
                       defaults to 'false')?                        
autoGenerateTestcaseScriptShould the driver dump the SQL it    false   3.1.9
                       is executing, including server-side          
                       prepared statements to STDERR?               
autoSlowLog            Instead of using                     true    5.1.4
                       slowQueryThreshold* to determine if          
                       a query is slow enough to be                 
                       logged, maintain statistics that             
                       allow the driver to determine                
                       queries that are outside the 99th            
                       percentile?                                  
clientInfoProvider     The name of a class that implements  com.mysql.jdbc.JDBC4CommentClientInfoProvider5.1.0
                       the                                          
                       com.mysql.jdbc.JDBC4ClientInfoProvider        
                       interface in order to support                
                       JDBC-4.0's                                   
                       Connection.get/setClientInfo()               
                       methods                                      
dumpMetadataOnColumnNotFoundShould the driver dump the           false   3.1.13
                       field-level metadata of a result             
                       set into the exception message when          
                       ResultSet.findColumn() fails?                
dumpQueriesOnException Should the driver dump the contents  false   3.1.3
                       of the query sent to the server in           
                       the message for SQLExceptions?               
enablePacketDebug      When enabled, a ring-buffer of       false   3.1.3
                       'packetDebugBufferSize' packets              
                       will be kept, and dumped when                
                       exceptions are thrown in key areas           
                       in the driver's code                         
explainSlowQueries     If 'logSlowQueries' is enabled,      false   3.1.2
                       should the driver automatically              
                       issue an 'EXPLAIN' on the server             
                       and send the results to the                  
                       configured log at a WARN level?              
includeInnodbStatusInDeadlockExceptionsInclude the output of "SHOW ENGINE   false   5.0.7
                       INNODB STATUS" in exception messages         
                       when deadlock exceptions are                 
                       detected?                                    
logSlowQueries         Should queries that take longer      false   3.1.2
                       than 'slowQueryThresholdMillis' be           
                       logged?                                      
logXaCommands          Should the driver log XA commands    false   5.0.5
                       sent by MysqlXaConnection to the             
                       server, at the DEBUG level of                
                       logging?                                     
profilerEventHandler   Name of a class that implements the  com.mysql.jdbc.profiler.LoggingProfilerEventHandler5.1.6
                       interface                                    
                       com.mysql.jdbc.profiler.ProfilerEventHandler        
                       that will be used to handle                  
                       profiling/tracing events.                    
resultSetSizeThreshold If the usage advisor is enabled,     100     5.0.5
                       how many rows should a result set            
                       contain before the driver warns              
                       that it is suspiciously large?               
traceProtocol          Should trace-level network protocol  false   3.1.2
                       be logged?                                   
useNanosForElapsedTime For profiling/debugging              false   5.0.7
                       functionality that measures elapsed          
                       time, should the driver try to use           
                       nanoseconds resolution if available          
                       (JDK >= 1.5)?                                

Miscellaneous

* Property Name *      * Definition *                       *       *
                                                            Default Since
                                                            Value * Version
                                                                    *
useUnicode             Should the driver use Unicode        true    1.1g
                       character encodings when handling            
                       strings?  Should only be used when           
                       the driver can't determine the               
                       character set mapping, or you are            
                       trying to 'force' the driver to use          
                       a character set that MySQL either            
                       doesn't natively support (such as            
                       UTF-8), true/false, defaults to              
                       'true'                                       
characterEncoding      If 'useUnicode' is set to true,              1.1g
                       what character encoding should the           
                       driver use when dealing with                 
                       strings? (defaults is to                     
                       'autodetect')                                
characterSetResults    Character set to tell the server to          3.0.13
                       return results as.                           
connectionCollation    If set, tells the server to use              3.0.13
                       this collation via 'set                      
                       collation_connection'                        
useBlobToStoreUTF8OutsideBMPTells the driver to treat            false   5.1.3
                       [MEDIUM/LONG]BLOB columns as                 
                       [LONG]VARCHAR columns holding text           
                       encoded in UTF-8 that has                    
                       characters outside the BMP (4-byte           
                       encodings), which MySQL server               
                       can't handle natively.                       
utf8OutsideBmpExcludedColumnNamePatternWhen "useBlobToStoreUTF8OutsideBMP"          5.1.3
                       is set to "true", column names               
                       matching the given regex will still          
                       be treated as BLOBs unless they              
                       match the regex specified for                
                       "utf8OutsideBmpIncludedColumnNamePattern".        
                       The regex must follow the patterns           
                       used for the java.util.regex                 
                       package.                                     
utf8OutsideBmpIncludedColumnNamePatternUsed to specify exclusion rules to           5.1.3
                       "utf8OutsideBmpExcludedColumnNamePattern".        
                       The regex must follow the patterns           
                       used for the java.util.regex                 
                       package.                                     
sessionVariables       A comma-separated list of                    3.1.8
                       name/value pairs to be sent as SET           
                       SESSION ...  to the server when the          
                       driver connects.                             
allowNanAndInf         Should the driver allow NaN or +/-   false   3.1.5
                       INF values in                                
                       PreparedStatement.setDouble()?               
autoClosePStmtStreams  Should the driver automatically      false   3.1.12
                       call .close() on streams/readers             
                       passed as arguments via set*()               
                       methods?                                     
autoDeserialize        Should the driver automatically      false   3.1.5
                       detect and de-serialize objects              
                       stored in BLOB fields?                       
blobsAreStrings        Should the driver always treat       false   5.0.8
                       BLOBs as Strings - specifically to           
                       work around dubious metadata                 
                       returned by the server for GROUP BY          
                       clauses?                                     
capitalizeTypeNames    Capitalize type names in             true    2.0.7
                       DatabaseMetaData? (usually only              
                       useful when using WebObjects,                
                       true/false, defaults to 'false')             
clobCharacterEncoding  The character encoding to use for            5.0.0
                       sending and retrieving TEXT,                 
                       MEDIUMTEXT and LONGTEXT values               
                       instead of the configured                    
                       connection characterEncoding                 
clobberStreamingResultsThis will cause a 'streaming'        false   3.0.9
                       ResultSet to be automatically                
                       closed, and any outstanding data             
                       still streaming from the server to           
                       be discarded if another query is             
                       executed before all the data has             
                       been read from the server.                   
continueBatchOnError   Should the driver continue           true    3.0.3
                       processing batch commands if one             
                       statement fails. The JDBC spec               
                       allows either way (defaults to               
                       'true').                                     
createDatabaseIfNotExistCreates the database given in the    false   3.1.9
                       URL if it doesn't yet exist. Assumes         
                       the configured user has permissions          
                       to create databases.                         
emptyStringsConvertToZeroShould the driver allow conversions  true    3.1.8
                       from empty string fields to numeric          
                       values of '0'?                               
emulateLocators        Should the driver emulate            false   3.1.0
                       java.sql.Blobs with locators? With           
                       this feature enabled, the driver             
                       will delay loading the actual Blob           
                       data until the one of the retrieval          
                       methods (getInputStream(),                   
                       getBytes(), and so forth) on the             
                       blob data stream has been accessed.          
                       For this to work, you must use a             
                       column alias with the value of the           
                       column to the actual name of the             
                       Blob. The feature also has the               
                       following restrictions: The SELECT           
                       that created the result set must             
                       reference only one table, the table          
                       must have a primary key; the SELECT          
                       must alias the original blob column          
                       name, specified as a string, to an           
                       alternate name; the SELECT must              
                       cover all columns that make up the           
                       primary key.                                 
emulateUnsupportedPstmtsShould the driver detect prepared    true    3.1.7
                       statements that are not supported by         
                       the server, and replace them with            
                       client-side emulated versions?               
functionsNeverReturnBlobsShould the driver always treat data  false   5.0.8
                       from functions returning BLOBs as            
                       Strings - specifically to work               
                       around dubious metadata returned by          
                       the server for GROUP BY clauses?             
generateSimpleParameterMetadataShould the driver generate           false   5.0.5
                       simplified parameter metadata for            
                       PreparedStatements when no metadata          
                       is available either because the              
                       server couldn't support preparing            
                       the statement, or server-side                
                       prepared statements are disabled?            
ignoreNonTxTables      Ignore non-transactional table       false   3.0.9
                       warning for rollback? (defaults to           
                       'false').                                    
jdbcCompliantTruncationShould the driver throw              true    3.1.2
                       java.sql.DataTruncation exceptions           
                       when data is truncated as is                 
                       required by the JDBC specification           
                       when connected to a server that              
                       supports warnings (MySQL 4.1.0 and           
                       newer)? This property has no effect          
                       if the server sql-mode includes              
                       STRICT_TRANS_TABLES.                         
maxRows                The maximum number of rows to        -1      all
                       return (0, the default means return          versions
                       all rows).                                   
netTimeoutForStreamingResultsWhat value should the driver         600     5.1.0
                       automatically set the server setting         
                       'net_write_timeout' to when the              
                       streaming result sets feature is in          
                       use? (value has unit of seconds,             
                       the value '0' means the driver will          
                       not try and adjust this value)               
noAccessToProcedureBodiesWhen determining procedure           false   5.0.3
                       parameter types for                          
                       CallableStatements, and the                  
                       connected user can't access                  
                       procedure bodies through "SHOW               
                       CREATE PROCEDURE" or select on               
                       mysql.proc should the driver                 
                       instead create basic metadata (all           
                       parameters reported as IN VARCHARs,          
                       but allowing registerOutParameter()          
                       to be called on them anyway)                 
                       instead of throwing an exception?            
noDatetimeStringSync   Don't ensure that                    false   3.1.7
                       ResultSet.getDatetimeType().toString().equals(ResultSet.getString())        
noTimezoneConversionForTimeTypeDon't convert TIME values using the  false   5.0.0
                       server timezone if                           
                       'useTimezone'='true'                         
nullCatalogMeansCurrentWhen DatabaseMetadataMethods ask     true    3.1.8
                       for a 'catalog' parameter, does the          
                       value null mean use the current              
                       catalog? (this is not                        
                       JDBC-compliant, but follows legacy           
                       behavior from earlier versions of            
                       the driver)                                  
nullNamePatternMatchesAllShould DatabaseMetaData methods      true    3.1.8
                       that accept *pattern parameters              
                       treat null the same as '%' (this is          
                       not JDBC-compliant, however older            
                       versions of the driver accepted this         
                       departure from the specification)            
overrideSupportsIntegrityEnhancementFacilityShould the driver return "true" for  false   3.1.12
                       DatabaseMetaData.supportsIntegrityEnhancementFacility()        
                       even if the database doesn't                 
                       support it to workaround                     
                       applications that require this               
                       method to return "true" to signal            
                       support of foreign keys, even                
                       though the SQL specification states          
                       that this facility contains much             
                       more than just foreign key support           
                       (one such application being                  
                       OpenOffice)?                                 
padCharsWithSpace      If a result set column has the CHAR  false   5.0.6
                       type and the value does not fill the         
                       amount of characters specified in            
                       the DDL for the column, should the           
                       driver pad the remaining characters          
                       with space (for ANSI compliance)?            
pedantic               Follow the JDBC spec to the letter.  false   3.0.0
pinGlobalTxToPhysicalConnectionWhen using XAConnections, should     false   5.0.1
                       the driver ensure that operations            
                       on a given XID are always routed to          
                       the same physical connection? This           
                       allows the XAConnection to support           
                       "XA START ... JOIN" after "XA END"           
                       has been called                              
populateInsertRowWithDefaultValuesWhen using ResultSets that are       false   5.0.5
                       CONCUR_UPDATABLE, should the driver          
                       pre-populate the "insert" row with           
                       default values from the DDL for the          
                       table used in the query so those             
                       values are immediately available             
                       for ResultSet accessors? This                
                       functionality requires a call to             
                       the database for metadata each time          
                       a result set of this type is                 
                       created.  If disabled (the                   
                       default), the default values will be         
                       populated by the an internal call            
                       to refreshRow() which pulls back             
                       default values and/or values                 
                       changed by triggers.                         
processEscapeCodesForPrepStmtsShould the driver process escape     true    3.1.12
                       codes in queries that are prepared?          
relaxAutoCommit        If the version of MySQL the driver   false   2.0.13
                       connects to does not support                 
                       transactions, still allow calls to           
                       commit(), rollback() and                     
                       setAutoCommit() (true/false,                 
                       defaults to 'false')?                        
retainStatementAfterResultSetCloseShould the driver retain the         false   3.1.11
                       Statement reference in a ResultSet           
                       after ResultSet.close() has been             
                       called. This is not JDBC-compliant           
                       after JDBC-4.0.                              
rollbackOnPooledClose  Should the driver issue a            true    3.0.15
                       rollback() when the logical                  
                       connection in a pool is closed?              
runningCTS13           Enables workarounds for bugs in      false   3.1.7
                       Sun's JDBC compliance testsuite              
                       version 1.3                                  
serverTimezone         Override detection/mapping of                3.0.2
                       timezone. Used when timezone from            
                       server doesn't map to Java timezone          
statementInterceptors  A comma-delimited list of classes            5.1.1
                       that implement                               
                       "com.mysql.jdbc.StatementInterceptor"        
                       that should be placed "in between"           
                       query execution to influence the             
                       results. StatementInterceptors are           
                       "chainable", the results returned            
                       by the "current" interceptor will be         
                       passed on to the next in in the              
                       chain, from left-to-right order, as          
                       specified in this property.                  
strictFloatingPoint    Used only in older versions of       false   3.0.0
                       compliance test                              
strictUpdates          Should the driver do strict          true    3.0.4
                       checking (all primary keys                   
                       selected) of updatable result sets           
                       (true, false, defaults to 'true')?           
tinyInt1isBit          Should the driver treat the          true    3.0.16
                       datatype TINYINT(1) as the BIT type          
                       (because the server silently                 
                       converts BIT -> TINYINT(1) when              
                       creating tables)?                            
transformedBitIsBooleanIf the driver converts TINYINT(1)    false   3.1.9
                       to a different type, should it use           
                       BOOLEAN instead of BIT for future            
                       compatibility with MySQL-5.0, as             
                       MySQL-5.0 has a BIT type?                    
treatUtilDateAsTimestampShould the driver treat              true    5.0.5
                       java.util.Date as a TIMESTAMP for            
                       the purposes of                              
                       PreparedStatement.setObject()?               
ultraDevHack           Create PreparedStatements for        false   2.0.3
                       prepareCall() when required, because         
                       UltraDev is broken and issues a              
                       prepareCall() for _all_ statements?          
                       (true/false, defaults to 'false')            
useGmtMillisForDatetimesConvert between session timezone     false   3.1.12
                       and GMT before creating Date and             
                       Timestamp instances (value of                
                       "false" is legacy behavior, "true"           
                       leads to more JDBC-compliant                 
                       behavior.                                    
useHostsInPrivileges   Add '@hostname' to users in          true    3.0.2
                       DatabaseMetaData.getColumn/TablePrivileges()        
                       (true/false), defaults to 'true'.            
useInformationSchema   When connected to MySQL-5.0.7 or     false   5.0.0
                       newer, should the driver use the             
                       INFORMATION_SCHEMA to derive                 
                       information used by                          
                       DatabaseMetaData?                            
useJDBCCompliantTimezoneShiftShould the driver use                false   5.0.0
                       JDBC-compliant rules when converting         
                       TIME/TIMESTAMP/DATETIME values'              
                       timezone information for those JDBC          
                       arguments which take a                       
                       java.util.Calendar argument?                 
                       (Notice that this option is                  
                       exclusive of the "useTimezone=true"          
                       configuration option.)                       
useLegacyDatetimeCode  Use code for                         true    5.1.6
                       DATE/TIME/DATETIME/TIMESTAMP                 
                       handling in result sets and                  
                       statements that consistently                 
                       handles timezone conversions from            
                       client to server and back again, or          
                       use the legacy code for these                
                       datatypes that has been in the               
                       driver for backwards-compatibility?          
useOldAliasMetadataBehaviorShould the driver use the legacy     false   5.0.4
                       behavior for "AS" clauses on columns         
                       and tables, and only return aliases          
                       (if any) for                                 
                       ResultSetMetaData.getColumnName() or         
                       ResultSetMetaData.getTableName()             
                       rather than the original                     
                       column/table name? In 5.0.x, the             
                       default value was true.                      
useOldUTF8Behavior     Use the UTF-8 behavior the driver    false   3.1.6
                       did when communicating with 4.0 and          
                       older servers                                
useOnlyServerErrorMessagesDon't prepend 'standard' SQLState    true    3.0.15
                       error messages to error messages             
                       returned by the server.                      
useSSPSCompatibleTimezoneShiftIf migrating from an environment     false   5.0.5
                       that was using server-side prepared          
                       statements, and the configuration            
                       property                                     
                       "useJDBCCompliantTimeZoneShift" set          
                       to "true", use compatible behavior           
                       when not using server-side prepared          
                       statements when sending TIMESTAMP            
                       values to the MySQL server.                  
useServerPrepStmts     Use server-side prepared statements  false   3.1.0
                       if the server supports them?                 
useSqlStateCodes       Use SQL Standard state codes         true    3.1.3
                       instead of 'legacy' X/Open/SQL               
                       state codes (true/false), default            
                       is 'true'                                    
useStreamLengthsInPrepStmtsHonor stream length parameter in     true    3.0.2
                       PreparedStatement/ResultSet.setXXXStream()        
                       method calls (true/false, defaults           
                       to 'true')?                                  
useTimezone            Convert time/date types between      false   3.0.2
                       client and server timezones                  
                       (true/false, defaults to 'false')?           
useUnbufferedInput     Don't use BufferedInputStream for    true    3.0.11
                       reading data from the server                 
yearIsDateType         Should the JDBC driver treat the     true    3.1.9
                       MySQL type "YEAR" as a                       
                       java.sql.Date, or as a SHORT?                
zeroDateTimeBehavior   What should happen when the driver   exception3.1.4
                       encounters DATETIME values that are          
                       composed entirely of zeroes (used            
                       by MySQL to represent invalid                
                       dates)? Valid values are                     
                       "exception", "round" and                     
                       "convertToNull".                             

Connector/J also supports access to MySQL via named pipes on Windows
NT/2000/XP using the NamedPipeSocketFactory as a plugin-socket factory
via the socketFactory property. If you don't use a namedPipePath
property, the default of '\\.\pipe\MySQL' will be used. If you use the
`NamedPipeSocketFactory', the hostname and port number values in the
JDBC url will be ignored. You can enable this feature using:

     socketFactory=com.mysql.jdbc.NamedPipeSocketFactory

Named pipes only work when connecting to a MySQL server on the same
physical machine as the one the JDBC driver is being used on. In simple
performance tests, it appears that named pipe access is between 30%-50%
faster than the standard TCP/IP access. However, this varies per
system, and named pipes are slower than TCP/IP in many Windows
configurations.

You can create your own socket factories by following the example code
in com.mysql.jdbc.NamedPipeSocketFactory, or
com.mysql.jdbc.StandardSocketFactory.


File: manual.info,  Node: connector-j-reference-implementation-notes,  Next: connector-j-reference-type-conversions,  Prev: connector-j-reference-configuration-properties,  Up: connector-j-reference

30.4.4.2 JDBC API Implementation Notes
......................................

MySQL Connector/J passes all of the tests in the publicly-available
version of Sun's JDBC compliance test suite.  However, in many places
the JDBC specification is vague about how certain functionality should
be implemented, or the specification allows leeway in implementation.

This section gives details on a interface-by-interface level about how
certain implementation decisions may affect how you use MySQL
Connector/J.

   * *Blob*

     Starting with Connector/J version 3.1.0, you can emulate Blobs
     with locators by adding the property 'emulateLocators=true' to
     your JDBC URL. Using this method, the driver will delay loading
     the actual Blob data until you retrieve the other data and then
     use retrieval methods (`getInputStream()', `getBytes()', and so
     forth) on the blob data stream.

     For this to work, you must use a column alias with the value of
     the column to the actual name of the Blob, for example:

          SELECT id, 'data' as blob_data from blobtable

     For this to work, you must also follow these rules:

        * The `SELECT' must also reference only one table, the table
          must have a primary key.

        * The `SELECT' must alias the original blob column name,
          specified as a string, to an alternate name.

        * The `SELECT' must cover all columns that make up the primary
          key.

     The Blob implementation does not allow in-place modification (they
     are copies, as reported by the
     `DatabaseMetaData.locatorsUpdateCopies()' method). Because of
     this, you should use the corresponding
     `PreparedStatement.setBlob()' or `ResultSet.updateBlob()' (in the
     case of updatable result sets) methods to save changes back to the
     database.

     MySQL Enterprise

     MySQL Enterprise subscribers will find more information about type
     conversion in the Knowledge Base article, Type Conversions
     Supported by MySQL Connector/J
     (https://kb.mysql.com/view.php?id=4929). To subscribe to MySQL
     Enterprise see
     `http://www.mysql.com/products/enterprise/advisors.html'.

   * *CallableStatement*

     Starting with Connector/J 3.1.1, stored procedures are supported
     when connecting to MySQL version 5.0 or newer via the
     CallableStatement interface.  Currently, the
     `getParameterMetaData()' method of CallableStatement is not
     supported.

   * *Clob*

     The Clob implementation does not allow in-place modification (they
     are copies, as reported by the
     `DatabaseMetaData.locatorsUpdateCopies()' method). Because of
     this, you should use the `PreparedStatement.setClob()' method to
     save changes back to the database. The JDBC API does not have a
     `ResultSet.updateClob()' method.

   * *Connection*

     Unlike older versions of MM.MySQL the `isClosed()' method does not
     ping the server to determine if it is alive. In accordance with the
     JDBC specification, it only returns true if `closed()' has been
     called on the connection. If you need to determine if the
     connection is still valid, you should issue a simple query, such as
     `SELECT 1'. The driver will throw an exception if the connection
     is no longer valid.

   * *DatabaseMetaData*

     Foreign Key information (`getImportedKeys()'/`getExportedKeys()'
     and `getCrossReference()') is only available from InnoDB tables.
     However, the driver uses `SHOW CREATE TABLE' to retrieve this
     information, so when other storage engines support foreign keys,
     the driver will transparently support them as well.

   * *PreparedStatement*

     PreparedStatements are implemented by the driver, as MySQL does
     not have a prepared statement feature. Because of this, the driver
     does not implement `getParameterMetaData()' or `getMetaData()' as
     it would require the driver to have a complete SQL parser in the
     client.

     Starting with version 3.1.0 MySQL Connector/J, server-side
     prepared statements and binary-encoded result sets are used when
     the server supports them.

     Take care when using a server-side prepared statement with *large*
     parameters that are set via `setBinaryStream()',
     `setAsciiStream()', `setUnicodeStream()', `setBlob()', or
     `setClob()'. If you want to re-execute the statement with any
     large parameter changed to a non-large parameter, it is necessary
     to call `clearParameters()' and set all parameters again. The
     reason for this is as follows:

        * During both server-side prepared statements and client-side
          emulation, large data is exchanged only when
          `PreparedStatement.execute()' is called.

        * Once that has been done, the stream used to read the data on
          the client side is closed (as per the JDBC spec), and can't
          be read from again.

        * If a parameter changes from large to non-large, the driver
          must reset the server-side state of the prepared statement to
          allow the parameter that is being changed to take the place
          of the prior large value. This removes all of the large data
          that has already been sent to the server, thus requiring the
          data to be re-sent, via the `setBinaryStream()',
          `setAsciiStream()', `setUnicodeStream()', `setBlob()' or
          `setClob()' methods.

     Consequently, if you want to change the type of a parameter to a
     non-large one, you must call `clearParameters()' and set all
     parameters of the prepared statement again before it can be
     re-executed.

   * *ResultSet*

     By default, ResultSets are completely retrieved and stored in
     memory. In most cases this is the most efficient way to operate,
     and due to the design of the MySQL network protocol is easier to
     implement. If you are working with ResultSets that have a large
     number of rows or large values, and can not allocate heap space in
     your JVM for the memory required, you can tell the driver to
     stream the results back one row at a time.

     To enable this functionality, you need to create a Statement
     instance in the following manner:

          stmt = conn.createStatement(java.sql.ResultSet.TYPE_FORWARD_ONLY,
                        java.sql.ResultSet.CONCUR_READ_ONLY);
          stmt.setFetchSize(Integer.MIN_VALUE);

     The combination of a forward-only, read-only result set, with a
     fetch size of `Integer.MIN_VALUE' serves as a signal to the driver
     to stream result sets row-by-row. After this any result sets
     created with the statement will be retrieved row-by-row.

     There are some caveats with this approach. You will have to read
     all of the rows in the result set (or close it) before you can
     issue any other queries on the connection, or an exception will be
     thrown.

     The earliest the locks these statements hold can be released
     (whether they be `MyISAM' table-level locks or row-level locks in
     some other storage engine such as `InnoDB') is when the statement
     completes.

     If the statement is within scope of a transaction, then locks are
     released when the transaction completes (which implies that the
     statement needs to complete first). As with most other databases,
     statements are not complete until all the results pending on the
     statement are read or the active result set for the statement is
     closed.

     Therefore, if using streaming results, you should process them as
     quickly as possible if you want to maintain concurrent access to
     the tables referenced by the statement producing the result set.

   * *ResultSetMetaData*

     The `isAutoIncrement()' method only works when using MySQL servers
     4.0 and newer.

   * *Statement*

     When using versions of the JDBC driver earlier than 3.2.1, and
     connected to server versions earlier than 5.0.3, the
     `setFetchSize()' method has no effect, other than to toggle result
     set streaming as described above.

     Connector/J 5.0.0 and later include support for both
     `Statement.cancel()' and `Statement.setQueryTimeout()'. Both
     require MySQL 5.0.0 or newer server, and require a separate
     connection to issue the `KILL QUERY' statement. In the case of
     `setQueryTimeout()', the implementation creates an additional
     thread to handle the timeout functionality.

     *Note*:

     Failures to cancel the statement for `setQueryTimeout()' may
     manifest themselves as `RuntimeException' rather than failing
     silently, as there is currently no way to unblock the thread that
     is executing the query being cancelled due to timeout expiration
     and have it throw the exception instead.

     MySQL does not support SQL cursors, and the JDBC driver doesn't
     emulate them, so "setCursorName()" has no effect.

     Connector/J 5.1.3 and later include two additional methods:

        * `setLocalInfileInputStream()' sets an `InputStream' instance
          that will be used to send data to the MySQL server for a
          `LOAD DATA LOCAL INFILE' statement rather than a
          `FileInputStream' or `URLInputStream' that represents the
          path given as an argument to the statement.

          This stream will be read to completion upon execution of a
          `LOAD DATA LOCAL INFILE' statement, and will automatically be
          closed by the driver, so it needs to be reset before each
          call to `execute*()' that would cause the MySQL server to
          request data to fulfill the request for `LOAD DATA LOCAL
          INFILE'.

          If this value is set to `NULL', the driver will revert to
          using a `FileInputStream' or `URLInputStream' as required.

        * `getLocalInfileInputStream()' returns the `InputStream'
          instance that will be used to send data in response to a
          `LOAD DATA LOCAL INFILE' statement.

          This method returns `NULL' if no such stream has been set via
          `setLocalInfileInputStream()'.


File: manual.info,  Node: connector-j-reference-type-conversions,  Next: connector-j-reference-charsets,  Prev: connector-j-reference-implementation-notes,  Up: connector-j-reference

30.4.4.3 Java, JDBC and MySQL Types
...................................

MySQL Connector/J is flexible in the way it handles conversions between
MySQL data types and Java data types.

In general, any MySQL data type can be converted to a java.lang.String,
and any numerical type can be converted to any of the Java numerical
types, although round-off, overflow, or loss of precision may occur.

Starting with Connector/J 3.1.0, the JDBC driver will issue warnings or
throw DataTruncation exceptions as is required by the JDBC
specification unless the connection was configured not to do so by
using the property jdbcCompliantTruncation and setting it to `false'.

The conversions that are always guaranteed to work are listed in the
following table:

Connection Properties - Miscellaneous

*These MySQL Data Types*             *Can always be converted to these
                                     Java types*
`CHAR, VARCHAR, BLOB, TEXT, ENUM,    `java.lang.String,
and SET'                             java.io.InputStream, java.io.Reader,
                                     java.sql.Blob, java.sql.Clob'
`FLOAT, REAL, DOUBLE PRECISION,      `java.lang.String, java.lang.Short,
NUMERIC, DECIMAL, TINYINT,           java.lang.Integer, java.lang.Long,
SMALLINT, MEDIUMINT, INTEGER,        java.lang.Double,
BIGINT'                              java.math.BigDecimal'
`DATE, TIME, DATETIME, TIMESTAMP'    `java.lang.String, java.sql.Date,
                                     java.sql.Timestamp'

*Note*:

Round-off, overflow or loss of precision may occur if you choose a Java
numeric data type that has less precision or capacity than the MySQL
data type you are converting to/from.

The ResultSet.getObject() method uses the type conversions between
MySQL and Java types, following the JDBC specification where
appropriate. The value returned by
ResultSetMetaData.GetColumnClassName() is also shown below. For more
information on the `java.sql.Types' classes see Java 2 Platform Types
(http://java.sun.com/j2se/1.4.2/docs/api/java/sql/Types.html).

MySQL Types to Java Types for ResultSet.getObject()

*MySQL Type Name*  *Return value of   *Returned as Java Class*
                   `GetColumnClassName'*
BIT(1) (new in     BIT                java.lang.Boolean
MySQL-5.0)                            
BIT( > 1) (new in  BIT                byte[]
MySQL-5.0)                            
TINYINT            TINYINT            java.lang.Boolean if the
                                      configuration property
                                      `tinyInt1isBit' is set to `true'
                                      (the default) and the storage size
                                      is 1, or java.lang.Integer if not.
BOOL, BOOLEAN      TINYINT            See TINYINT, above as these are
                                      aliases for TINYINT(1), currently.
SMALLINT[(M)]      SMALLINT           java.lang.Integer (regardless if
[UNSIGNED]         [UNSIGNED]         UNSIGNED or not)
MEDIUMINT[(M)]     MEDIUMINT          java.lang.Integer, if UNSIGNED
[UNSIGNED]         [UNSIGNED]         java.lang.Long (C/J 3.1 and
                                      earlier), or java.lang.Integer for
                                      C/J 5.0 and later
INT,INTEGER[(M)]   INTEGER [UNSIGNED] java.lang.Integer, if UNSIGNED
[UNSIGNED]                            java.lang.Long
BIGINT[(M)]        BIGINT [UNSIGNED]  java.lang.Long, if UNSIGNED
[UNSIGNED]                            java.math.BigInteger
FLOAT[(M,D)]       FLOAT              java.lang.Float
DOUBLE[(M,B)]      DOUBLE             java.lang.Double
DECIMAL[(M[,D])]   DECIMAL            java.math.BigDecimal
DATE               DATE               java.sql.Date
DATETIME           DATETIME           java.sql.Timestamp
TIMESTAMP[(M)]     TIMESTAMP          java.sql.Timestamp
TIME               TIME               java.sql.Time
YEAR[(2|4)]        YEAR               If `yearIsDateType' configuration
                                      property is set to false, then the
                                      returned object type is
                                      java.sql.Short. If set to true (the
                                      default) then an object of type
                                      java.sql.Date (with the date set to
                                      January 1st, at midnight).
CHAR(M)            CHAR               java.lang.String (unless the
                                      character set for the column is
                                      BINARY, then byte[] is returned.
VARCHAR(M)         VARCHAR            java.lang.String (unless the
[BINARY]                              character set for the column is
                                      BINARY, then byte[] is returned.
BINARY(M)          BINARY             byte[]
VARBINARY(M)       VARBINARY          byte[]
TINYBLOB           TINYBLOB           byte[]
TINYTEXT           VARCHAR            java.lang.String
BLOB               BLOB               byte[]
TEXT               VARCHAR            java.lang.String
MEDIUMBLOB         MEDIUMBLOB         byte[]
MEDIUMTEXT         VARCHAR            java.lang.String
LONGBLOB           LONGBLOB           byte[]
LONGTEXT           VARCHAR            java.lang.String
ENUM('value1','value2',...)CHAR               java.lang.String
SET('value1','value2',...)CHAR               java.lang.String


File: manual.info,  Node: connector-j-reference-charsets,  Next: connector-j-reference-using-ssl,  Prev: connector-j-reference-type-conversions,  Up: connector-j-reference

30.4.4.4 Using Character Sets and Unicode
.........................................

All strings sent from the JDBC driver to the server are converted
automatically from native Java Unicode form to the client character
encoding, including all queries sent via `Statement.execute()',
`Statement.executeUpdate()', `Statement.executeQuery()' as well as all

PreparedStatement

and

CallableStatement

parameters with the exclusion of parameters set using `setBytes()',
`setBinaryStream()', `setAsciiStream()', `setUnicodeStream()' and
`setBlob()'.

Prior to MySQL Server 4.1, Connector/J supported a single character
encoding per connection, which could either be automatically detected
from the server configuration, or could be configured by the user
through the useUnicode and characterEncoding properties.

Starting with MySQL Server 4.1, Connector/J supports a single character
encoding between client and server, and any number of character
encodings for data returned by the server to the client in ResultSets.

The character encoding between client and server is automatically
detected upon connection. The encoding used by the driver is specified
on the server via the `character_set' system variable for server
versions older than 4.1.0 and `character_set_server' for server versions
4.1.0 and newer. For more information, see *Note charset-server::.

To override the automatically-detected encoding on the client side, use
the characterEncoding property in the URL used to connect to the server.

When specifying character encodings on the client side, Java-style
names should be used. The following table lists Java-style names for
MySQL character sets:

MySQL to Java Encoding Name Translations

*MySQL Character Set Name*           *Java-Style Character Encoding Name*
ascii                                US-ASCII
big5                                 Big5
gbk                                  GBK
sjis                                 SJIS (or Cp932 or MS932 for MySQL
                                     Server < 4.1.11)
cp932                                Cp932 or MS932 (MySQL Server >
                                     4.1.11)
gb2312                               EUC_CN
ujis                                 EUC_JP
euckr                                EUC_KR
latin1                               ISO8859_1
latin2                               ISO8859_2
greek                                ISO8859_7
hebrew                               ISO8859_8
cp866                                Cp866
tis620                               TIS620
cp1250                               Cp1250
cp1251                               Cp1251
cp1257                               Cp1257
macroman                             MacRoman
macce                                MacCentralEurope
utf8                                 UTF-8
ucs2                                 UnicodeBig

*Warning*:

Do not issue the query 'set names' with Connector/J, as the driver will
not detect that the character set has changed, and will continue to use
the character set detected during the initial connection setup.

To allow multiple character sets to be sent from the client, the UTF-8
encoding should be used, either by configuring `utf8' as the default
server character set, or by configuring the JDBC driver to use UTF-8
through the characterEncoding property.


File: manual.info,  Node: connector-j-reference-using-ssl,  Next: connector-j-reference-replication-connection,  Prev: connector-j-reference-charsets,  Up: connector-j-reference

30.4.4.5 Connecting Securely Using SSL
......................................

SSL in MySQL Connector/J encrypts all data (other than the initial
handshake) between the JDBC driver and the server. The performance
penalty for enabling SSL is an increase in query processing time
between 35% and 50%, depending on the size of the query, and the amount
of data it returns.

For SSL Support to work, you must have the following:

   * A JDK that includes JSSE (Java Secure Sockets Extension), like
     JDK-1.4.1 or newer. SSL does not currently work with a JDK that
     you can add JSSE to, like JDK-1.2.x or JDK-1.3.x due to the
     following JSSE bug:
     `http://developer.java.sun.com/developer/bugParade/bugs/4273544.html'

   * A MySQL server that supports SSL and has been compiled and
     configured to do so, which is MySQL-4.0.4 or later, see *Note
     secure-connections::, for more information.

   * A client certificate (covered later in this section)

The system works through two Java truststore files, one file contains
the certificate information for the server (`truststore' in the
examples below). The other file contains the certificate for the client
(`keystore' in the examples below). All Java truststore files are
password protected by supplying a suitable password to the `keytool'
when you create the files. You need the file names and associated
passwords to create an SSL connection.

You will first need to import the MySQL server CA Certificate into a
Java truststore. A sample MySQL server CA Certificate is located in the
`SSL' subdirectory of the MySQL source distribution. This is what SSL
will use to determine if you are communicating with a secure MySQL
server.  Alternatively, use the CA Certificate that you have generated
or been provided with by your SSL provider.

To use Java's `keytool' to create a truststore in the current directory
, and import the server's CA certificate (`cacert.pem'), you can do the
following (assuming that `keytool' is in your path. The `keytool'
should be located in the `bin' subdirectory of your JDK or JRE):

     shell> keytool -import -alias mysqlServerCACert \
                                       -file cacert.pem -keystore truststore

You will need to enter the password when prompted for the keystore
file. Interaction with `keytool' will look like this:

     Enter keystore password:  *********
     Owner: EMAILADDRESS=walrus@example.com, CN=Walrus,
            O=MySQL AB, L=Orenburg, ST=Some-State, C=RU
     Issuer: EMAILADDRESS=walrus@example.com, CN=Walrus,
            O=MySQL AB, L=Orenburg, ST=Some-State, C=RU
     Serial number: 0
     Valid from:
        Fri Aug 02 16:55:53 CDT 2002 until: Sat Aug 02 16:55:53 CDT 2003
     Certificate fingerprints:
         MD5:  61:91:A0:F2:03:07:61:7A:81:38:66:DA:19:C4:8D:AB
         SHA1: 25:77:41:05:D5:AD:99:8C:14:8C:CA:68:9C:2F:B8:89:C3:34:4D:6C
     Trust this certificate? [no]:  yes
     Certificate was added to keystore

You then have two options, you can either import the client certificate
that matches the CA certificate you just imported, or you can create a
new client certificate.

To import an existing certificate, the certificate should be in DER
format. You can use `openssl' to convert an existing certificate into
the new format. For example:

     shell> openssl x509 -outform DER -in client-cert.pem -out client.cert

You now need to import the converted certificate into your keystore
using `keytool':

     shell> keytool -import -file client.cert -keystore keystore -alias mysqlClientCertificate

To generate your own client certificate, use `keytool' to create a
suitable certificate and add it to the `keystore' file:

      shell> keytool -genkey -keyalg rsa \
          -alias mysqlClientCertificate -keystore keystore

Keytool will prompt you for the following information, and create a
keystore named `keystore' in the current directory.

You should respond with information that is appropriate for your
situation:

     Enter keystore password:  *********
     What is your first and last name?
       [Unknown]:  Matthews
     What is the name of your organizational unit?
       [Unknown]:  Software Development
     What is the name of your organization?
       [Unknown]:  MySQL AB
     What is the name of your City or Locality?
       [Unknown]:  Flossmoor
     What is the name of your State or Province?
       [Unknown]:  IL
     What is the two-letter country code for this unit?
       [Unknown]:  US
     Is <CN=Matthews, OU=Software Development, O=MySQL AB,
      L=Flossmoor, ST=IL, C=US> correct?
       [no]:  y

     Enter key password for <mysqlClientCertificate>
             (RETURN if same as keystore password):

Finally, to get JSSE to use the keystore and truststore that you have
generated, you need to set the following system properties when you
start your JVM, replacing path_to_keystore_file with the full path to
the keystore file you created, path_to_truststore_file with the path to
the truststore file you created, and using the appropriate password
values for each property. You can do this either on the command line:

     -Djavax.net.ssl.keyStore=path_to_keystore_file
     -Djavax.net.ssl.keyStorePassword=password
     -Djavax.net.ssl.trustStore=path_to_truststore_file
     -Djavax.net.ssl.trustStorePassword=password

Or you can set the values directly within the application:

      System.setProperty("javax.net.ssl.keyStore","path_to_keystore_file");
     System.setProperty("javax.net.ssl.keyStorePassword","password");
     System.setProperty("javax.net.ssl.trustStore","path_to_truststore_file");
     System.setProperty("javax.net.ssl.trustStorePassword","password");

You will also need to set useSSL to `true' in your connection
parameters for MySQL Connector/J, either by adding `useSSL=true' to
your URL, or by setting the property useSSL to `true' in the
java.util.Properties instance you pass to
`DriverManager.getConnection()'.

You can test that SSL is working by turning on JSSE debugging (as
detailed below), and look for the following key events:

     ...
     *** ClientHello, v3.1
     RandomCookie:  GMT: 1018531834 bytes = { 199, 148, 180, 215, 74, 12, »
       54, 244, 0, 168, 55, 103, 215, 64, 16, 138, 225, 190, 132, 153, 2, »
       217, 219, 239, 202, 19, 121, 78 }
     Session ID:  {}
     Cipher Suites:  { 0, 5, 0, 4, 0, 9, 0, 10, 0, 18, 0, 19, 0, 3, 0, 17 }
     Compression Methods:  { 0 }
     ***
     [write] MD5 and SHA1 hashes:  len = 59
     0000: 01 00 00 37 03 01 3D B6 90 FA C7 94 B4 D7 4A 0C  ...7..=.......J.
     0010: 36 F4 00 A8 37 67 D7 40 10 8A E1 BE 84 99 02 D9  6...7g.@........
     0020: DB EF CA 13 79 4E 00 00 10 00 05 00 04 00 09 00  ....yN..........
     0030: 0A 00 12 00 13 00 03 00 11 01 00                 ...........
     main, WRITE:  SSL v3.1 Handshake, length = 59
     main, READ:  SSL v3.1 Handshake, length = 74
     *** ServerHello, v3.1
     RandomCookie:  GMT: 1018577560 bytes = { 116, 50, 4, 103, 25, 100, 58, »
        202, 79, 185, 178, 100, 215, 66, 254, 21, 83, 187, 190, 42, 170, 3, »
        132, 110, 82, 148, 160, 92 }
     Session ID:  {163, 227, 84, 53, 81, 127, 252, 254, 178, 179, 68, 63, »
        182, 158, 30, 11, 150, 79, 170, 76, 255, 92, 15, 226, 24, 17, 177, »
        219, 158, 177, 187, 143}
     Cipher Suite:  { 0, 5 }
     Compression Method: 0
     ***
     %% Created:  [Session-1, SSL_RSA_WITH_RC4_128_SHA]
     ** SSL_RSA_WITH_RC4_128_SHA
     [read] MD5 and SHA1 hashes:  len = 74
     0000: 02 00 00 46 03 01 3D B6 43 98 74 32 04 67 19 64  ...F..=.C.t2.g.d
     0010: 3A CA 4F B9 B2 64 D7 42 FE 15 53 BB BE 2A AA 03  :.O..d.B..S..*..
     0020: 84 6E 52 94 A0 5C 20 A3 E3 54 35 51 7F FC FE B2  .nR..\ ..T5Q....
     0030: B3 44 3F B6 9E 1E 0B 96 4F AA 4C FF 5C 0F E2 18  .D?.....O.L.\...
     0040: 11 B1 DB 9E B1 BB 8F 00 05 00                    ..........
     main, READ:  SSL v3.1 Handshake, length = 1712
     ...

JSSE provides debugging (to STDOUT) when you set the following system
property: `-Djavax.net.debug=all' This will tell you what keystores and
truststores are being used, as well as what is going on during the SSL
handshake and certificate exchange. It will be helpful when trying to
determine what is not working when trying to get an SSL connection to
happen.


File: manual.info,  Node: connector-j-reference-replication-connection,  Next: connector-j-reference-error-sqlstates,  Prev: connector-j-reference-using-ssl,  Up: connector-j-reference

30.4.4.6 Using Master/Slave Replication with ReplicationConnection
..................................................................

Starting with Connector/J 3.1.7, we've made available a variant of the
driver that will automatically send queries to a read/write master, or
a failover or round-robin loadbalanced set of slaves based on the state
of `Connection.getReadOnly()' .

An application signals that it wants a transaction to be read-only by
calling `Connection.setReadOnly(true)', this replication-aware
connection will use one of the slave connections, which are
load-balanced per-vm using a round-robin scheme (a given connection is
sticky to a slave unless that slave is removed from service). If you
have a write transaction, or if you have a read that is time-sensitive
(remember, replication in MySQL is asynchronous), set the connection to
be not read-only, by calling `Connection.setReadOnly(false)' and the
driver will ensure that further calls are sent to the master MySQL
server. The driver takes care of propagating the current state of
autocommit, isolation level, and catalog between all of the connections
that it uses to accomplish this load balancing functionality.

To enable this functionality, use the "
`com.mysql.jdbc.ReplicationDriver' " class when configuring your
application server's connection pool or when creating an instance of a
JDBC driver for your standalone application. Because it accepts the
same URL format as the standard MySQL JDBC driver, `ReplicationDriver'
does not currently work with `java.sql.DriverManager' -based connection
creation unless it is the only MySQL JDBC driver registered with the
`DriverManager' .

Here is a short, simple example of how ReplicationDriver might be used
in a standalone application.

     import java.sql.Connection;
     import java.sql.ResultSet;
     import java.util.Properties;

     import com.mysql.jdbc.ReplicationDriver;

     public class ReplicationDriverDemo {

       public static void main(String[] args) throws Exception {
         ReplicationDriver driver = new ReplicationDriver();

         Properties props = new Properties();

         // We want this for failover on the slaves
         props.put("autoReconnect", "true");

         // We want to load balance between the slaves
         props.put("roundRobinLoadBalance", "true");

         props.put("user", "foo");
         props.put("password", "bar");

         //
         // Looks like a normal MySQL JDBC url, with a
         // comma-separated list of hosts, the first
         // being the 'master', the rest being any number
         // of slaves that the driver will load balance against
         //

         Connection conn =
             driver.connect("jdbc:mysql://master,slave1,slave2,slave3/test",
                 props);

         //
         // Perform read/write work on the master
         // by setting the read-only flag to "false"
         //

         conn.setReadOnly(false);
         conn.setAutoCommit(false);
         conn.createStatement().executeUpdate("UPDATE some_table ....");
         conn.commit();

         //
         // Now, do a query from a slave, the driver automatically picks one
         // from the list
         //

         conn.setReadOnly(true);

         ResultSet rs =
           conn.createStatement().executeQuery("SELECT a,b FROM alt_table");

          .......
       }
     }

You may also want to investigate the Load Balancing JDBC Pool (lbpol)
tool, which provides a wrapper around the standard JDBC driver and
allows you to use DB connection pools that includes checks for system
failures and uneven load distribution. For more information, see Load
Balancing JDBC Pool (lbpool) (http://code.tailrank.com/lbpool).


File: manual.info,  Node: connector-j-reference-error-sqlstates,  Prev: connector-j-reference-replication-connection,  Up: connector-j-reference

30.4.4.7 Mapping MySQL Error Numbers to SQLStates
.................................................

The table below provides a mapping of the MySQL Error Numbers to `SQL
States'

*Mapping of MySQL Error Numbers to SQLStates*

MySQL Error    MySQL Error Name              Legacy         SQL Standard
Number                                       (X/Open)       SQLState
                                             SQLState       
1022           ER_DUP_KEY                    S1000          23000
1037           ER_OUTOFMEMORY                S1001          HY001
1038           ER_OUT_OF_SORTMEMORY          S1001          HY001
1040           ER_CON_COUNT_ERROR            08004          08004
1042           ER_BAD_HOST_ERROR             08004          08S01
1043           ER_HANDSHAKE_ERROR            08004          08S01
1044           ER_DBACCESS_DENIED_ERROR      S1000          42000
1045           ER_ACCESS_DENIED_ERROR        28000          28000
1047           ER_UNKNOWN_COM_ERROR          08S01          HY000
1050           ER_TABLE_EXISTS_ERROR         S1000          42S01
1051           ER_BAD_TABLE_ERROR            42S02          42S02
1052           ER_NON_UNIQ_ERROR             S1000          23000
1053           ER_SERVER_SHUTDOWN            S1000          08S01
1054           ER_BAD_FIELD_ERROR            S0022          42S22
1055           ER_WRONG_FIELD_WITH_GROUP     S1009          42000
1056           ER_WRONG_GROUP_FIELD          S1009          42000
1057           ER_WRONG_SUM_SELECT           S1009          42000
1058           ER_WRONG_VALUE_COUNT          21S01          21S01
1059           ER_TOO_LONG_IDENT             S1009          42000
1060           ER_DUP_FIELDNAME              S1009          42S21
1061           ER_DUP_KEYNAME                S1009          42000
1062           ER_DUP_ENTRY                  S1009          23000
1063           ER_WRONG_FIELD_SPEC           S1009          42000
1064           ER_PARSE_ERROR                42000          42000
1065           ER_EMPTY_QUERY                42000          42000
1066           ER_NONUNIQ_TABLE              S1009          42000
1067           ER_INVALID_DEFAULT            S1009          42000
1068           ER_MULTIPLE_PRI_KEY           S1009          42000
1069           ER_TOO_MANY_KEYS              S1009          42000
1070           ER_TOO_MANY_KEY_PARTS         S1009          42000
1071           ER_TOO_LONG_KEY               S1009          42000
1072           ER_KEY_COLUMN_DOES_NOT_EXITS  S1009          42000
1073           ER_BLOB_USED_AS_KEY           S1009          42000
1074           ER_TOO_BIG_FIELDLENGTH        S1009          42000
1075           ER_WRONG_AUTO_KEY             S1009          42000
1080           ER_FORCING_CLOSE              S1000          08S01
1081           ER_IPSOCK_ERROR               08S01          08S01
1082           ER_NO_SUCH_INDEX              S1009          42S12
1083           ER_WRONG_FIELD_TERMINATORS    S1009          42000
1084           ER_BLOBS_AND_NO_TERMINATED    S1009          42000
1090           ER_CANT_REMOVE_ALL_FIELDS     S1000          42000
1091           ER_CANT_DROP_FIELD_OR_KEY     S1000          42000
1101           ER_BLOB_CANT_HAVE_DEFAULT     S1000          42000
1102           ER_WRONG_DB_NAME              S1000          42000
1103           ER_WRONG_TABLE_NAME           S1000          42000
1104           ER_TOO_BIG_SELECT             S1000          42000
1106           ER_UNKNOWN_PROCEDURE          S1000          42000
1107           ER_WRONG_PARAMCOUNT_TO_PROCEDURES1000          42000
1109           ER_UNKNOWN_TABLE              S1000          42S02
1110           ER_FIELD_SPECIFIED_TWICE      S1000          42000
1112           ER_UNSUPPORTED_EXTENSION      S1000          42000
1113           ER_TABLE_MUST_HAVE_COLUMNS    S1000          42000
1115           ER_UNKNOWN_CHARACTER_SET      S1000          42000
1118           ER_TOO_BIG_ROWSIZE            S1000          42000
1120           ER_WRONG_OUTER_JOIN           S1000          42000
1121           ER_NULL_COLUMN_IN_INDEX       S1000          42000
1129           ER_HOST_IS_BLOCKED            08004          HY000
1130           ER_HOST_NOT_PRIVILEGED        08004          HY000
1131           ER_PASSWORD_ANONYMOUS_USER    S1000          42000
1132           ER_PASSWORD_NOT_ALLOWED       S1000          42000
1133           ER_PASSWORD_NO_MATCH          S1000          42000
1136           ER_WRONG_VALUE_COUNT_ON_ROW   S1000          21S01
1138           ER_INVALID_USE_OF_NULL        S1000          42000
1139           ER_REGEXP_ERROR               S1000          42000
1140           ER_MIX_OF_GROUP_FUNC_AND_FIELDSS1000          42000
1141           ER_NONEXISTING_GRANT          S1000          42000
1142           ER_TABLEACCESS_DENIED_ERROR   S1000          42000
1143           ER_COLUMNACCESS_DENIED_ERROR  S1000          42000
1144           ER_ILLEGAL_GRANT_FOR_TABLE    S1000          42000
1145           ER_GRANT_WRONG_HOST_OR_USER   S1000          42000
1146           ER_NO_SUCH_TABLE              S1000          42S02
1147           ER_NONEXISTING_TABLE_GRANT    S1000          42000
1148           ER_NOT_ALLOWED_COMMAND        S1000          42000
1149           ER_SYNTAX_ERROR               S1000          42000
1152           ER_ABORTING_CONNECTION        S1000          08S01
1153           ER_NET_PACKET_TOO_LARGE       S1000          08S01
1154           ER_NET_READ_ERROR_FROM_PIPE   S1000          08S01
1155           ER_NET_FCNTL_ERROR            S1000          08S01
1156           ER_NET_PACKETS_OUT_OF_ORDER   S1000          08S01
1157           ER_NET_UNCOMPRESS_ERROR       S1000          08S01
1158           ER_NET_READ_ERROR             S1000          08S01
1159           ER_NET_READ_INTERRUPTED       S1000          08S01
1160           ER_NET_ERROR_ON_WRITE         S1000          08S01
1161           ER_NET_WRITE_INTERRUPTED      S1000          08S01
1162           ER_TOO_LONG_STRING            S1000          42000
1163           ER_TABLE_CANT_HANDLE_BLOB     S1000          42000
1164           ER_TABLE_CANT_HANDLE_AUTO_INCREMENTS1000          42000
1166           ER_WRONG_COLUMN_NAME          S1000          42000
1167           ER_WRONG_KEY_COLUMN           S1000          42000
1169           ER_DUP_UNIQUE                 S1000          23000
1170           ER_BLOB_KEY_WITHOUT_LENGTH    S1000          42000
1171           ER_PRIMARY_CANT_HAVE_NULL     S1000          42000
1172           ER_TOO_MANY_ROWS              S1000          42000
1173           ER_REQUIRES_PRIMARY_KEY       S1000          42000
1177           ER_CHECK_NO_SUCH_TABLE        S1000          42000
1178           ER_CHECK_NOT_IMPLEMENTED      S1000          42000
1179           ER_CANT_DO_THIS_DURING_AN_TRANSACTIONS1000          25000
1184           ER_NEW_ABORTING_CONNECTION    S1000          08S01
1189           ER_MASTER_NET_READ            S1000          08S01
1190           ER_MASTER_NET_WRITE           S1000          08S01
1203           ER_TOO_MANY_USER_CONNECTIONS  S1000          42000
1205           ER_LOCK_WAIT_TIMEOUT          41000          41000
1207           ER_READ_ONLY_TRANSACTION      S1000          25000
1211           ER_NO_PERMISSION_TO_CREATE_USERS1000          42000
1213           ER_LOCK_DEADLOCK              41000          40001
1216           ER_NO_REFERENCED_ROW          S1000          23000
1217           ER_ROW_IS_REFERENCED          S1000          23000
1218           ER_CONNECT_TO_MASTER          S1000          08S01
1222           ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECTS1000          21000
1226           ER_USER_LIMIT_REACHED         S1000          42000
1230           ER_NO_DEFAULT                 S1000          42000
1231           ER_WRONG_VALUE_FOR_VAR        S1000          42000
1232           ER_WRONG_TYPE_FOR_VAR         S1000          42000
1234           ER_CANT_USE_OPTION_HERE       S1000          42000
1235           ER_NOT_SUPPORTED_YET          S1000          42000
1239           ER_WRONG_FK_DEF               S1000          42000
1241           ER_OPERAND_COLUMNS            S1000          21000
1242           ER_SUBQUERY_NO_1_ROW          S1000          21000
1247           ER_ILLEGAL_REFERENCE          S1000          42S22
1248           ER_DERIVED_MUST_HAVE_ALIAS    S1000          42000
1249           ER_SELECT_REDUCED             S1000          01000
1250           ER_TABLENAME_NOT_ALLOWED_HERE S1000          42000
1251           ER_NOT_SUPPORTED_AUTH_MODE    S1000          08004
1252           ER_SPATIAL_CANT_HAVE_NULL     S1000          42000
1253           ER_COLLATION_CHARSET_MISMATCH S1000          42000
1261           ER_WARN_TOO_FEW_RECORDS       S1000          01000
1262           ER_WARN_TOO_MANY_RECORDS      S1000          01000
1263           ER_WARN_NULL_TO_NOTNULL       S1000          01000
1264           ER_WARN_DATA_OUT_OF_RANGE     S1000          01000
1265           ER_WARN_DATA_TRUNCATED        S1000          01000
1280           ER_WRONG_NAME_FOR_INDEX       S1000          42000
1281           ER_WRONG_NAME_FOR_CATALOG     S1000          42000
1286           ER_UNKNOWN_STORAGE_ENGINE     S1000          42000


File: manual.info,  Node: connector-j-usagenotes,  Next: connector-j-support,  Prev: connector-j-reference,  Up: connector-j

30.4.5 Connector/J Notes and Tips
---------------------------------

* Menu:

* connector-j-usagenotes-basic::  Basic JDBC Concepts
* connector-j-usagenotes-j2ee::  Using Connector/J with J2EE and Other Java Frameworks
* connector-j-usagenotes-troubleshooting::  Common Problems and Solutions


File: manual.info,  Node: connector-j-usagenotes-basic,  Next: connector-j-usagenotes-j2ee,  Prev: connector-j-usagenotes,  Up: connector-j-usagenotes

30.4.5.1 Basic JDBC Concepts
............................

* Menu:

* connector-j-usagenotes-connect-drivermanager::  Connecting to MySQL Using the `DriverManager' Interface
* connector-j-usagenotes-statements::  Using Statements to Execute SQL
* connector-j-usagenotes-statements-callable::  Using `CallableStatements' to Execute Stored Procedures
* connector-j-usagenotes-last-insert-id::  Retrieving `AUTO_INCREMENT' Column Values

This section provides some general JDBC background.


File: manual.info,  Node: connector-j-usagenotes-connect-drivermanager,  Next: connector-j-usagenotes-statements,  Prev: connector-j-usagenotes-basic,  Up: connector-j-usagenotes-basic

30.4.5.2 Connecting to MySQL Using the `DriverManager' Interface
................................................................

When you are using JDBC outside of an application server, the
`DriverManager' class manages the establishment of Connections.

The `DriverManager' needs to be told which JDBC drivers it should try
to make Connections with. The easiest way to do this is to use
`Class.forName()' on the class that implements the `java.sql.Driver'
interface.  With MySQL Connector/J, the name of this class is
`com.mysql.jdbc.Driver'. With this method, you could use an external
configuration file to supply the driver class name and driver
parameters to use when connecting to a database.

The following section of Java code shows how you might register MySQL
Connector/J from the `main()' method of your application:

     import java.sql.Connection;
     import java.sql.DriverManager;
     import java.sql.SQLException;

     // Notice, do not import com.mysql.jdbc.*
     // or you will have problems!

     public class LoadDriver {
         public static void main(String[] args) {
             try {
                 // The newInstance() call is a work around for some
                 // broken Java implementations

                 Class.forName("com.mysql.jdbc.Driver").newInstance();
             } catch (Exception ex) {
                 // handle the error
             }
     }

After the driver has been registered with the `DriverManager', you can
obtain a `Connection' instance that is connected to a particular
database by calling `DriverManager.getConnection()':

This example shows how you can obtain a `Connection' instance from the
`DriverManager'. There are a few different signatures for the
`getConnection()' method. You should see the API documentation that
comes with your JDK for more specific information on how to use them.

     import java.sql.Connection;
     import java.sql.DriverManager;
     import java.sql.SQLException;

     ...
     try {
         Connection conn =
            DriverManager.getConnection("jdbc:mysql://localhost/test?" +
                                        "user=monty&password=greatsqldb");

         // Do something with the Connection

        ...
     } catch (SQLException ex) {
         // handle any errors
         System.out.println("SQLException: " + ex.getMessage());
         System.out.println("SQLState: " + ex.getSQLState());
         System.out.println("VendorError: " + ex.getErrorCode());
     }

Once a Connection is established, it can be used to create Statement and
PreparedStatement objects, as well as retrieve metadata about the
database. This is explained in the following sections.


File: manual.info,  Node: connector-j-usagenotes-statements,  Next: connector-j-usagenotes-statements-callable,  Prev: connector-j-usagenotes-connect-drivermanager,  Up: connector-j-usagenotes-basic

30.4.5.3 Using Statements to Execute SQL
........................................

Statement objects allow you to execute basic SQL queries and retrieve
the results through the `ResultSet' class which is described later.

To create a Statement instance, you call the `createStatement()' method
on the `Connection' object you have retrieved via one of the
`DriverManager.getConnection()' or `DataSource.getConnection()' methods
described earlier.

Once you have a Statement instance, you can execute a `SELECT' query by
calling the `executeQuery(String)' method with the SQL you want to use.

To update data in the database, use the `executeUpdate(String SQL)'
method. This method returns the number of rows affected by the update
statement.

If you don't know ahead of time whether the SQL statement will be a
`SELECT' or an `UPDATE'/`INSERT', then you can use the `execute(String
SQL)' method.  This method will return true if the SQL query was a
`SELECT', or false if it was an `UPDATE', `INSERT', or `DELETE'
statement. If the statement was a `SELECT' query, you can retrieve the
results by calling the `getResultSet()' method. If the statement was an
`UPDATE', `INSERT', or `DELETE' statement, you can retrieve the
affected rows count by calling `getUpdateCount()' on the Statement
instance.

     // assume that conn is an already created JDBC connection
     Statement stmt = null;
     ResultSet rs = null;

     try {
         stmt = conn.createStatement();
         rs = stmt.executeQuery("SELECT foo FROM bar");

         // or alternatively, if you don't know ahead of time that
         // the query will be a SELECT...

         if (stmt.execute("SELECT foo FROM bar")) {
             rs = stmt.getResultSet();
         }

         // Now do something with the ResultSet ....
     } finally {
         // it is a good idea to release
         // resources in a finally{} block
         // in reverse-order of their creation
         // if they are no-longer needed

         if (rs != null) {
             try {
                 rs.close();
             } catch (SQLException sqlEx) { // ignore }

             rs = null;
         }

         if (stmt != null) {
             try {
                 stmt.close();
             } catch (SQLException sqlEx) { // ignore }

             stmt = null;
         }
     }


File: manual.info,  Node: connector-j-usagenotes-statements-callable,  Next: connector-j-usagenotes-last-insert-id,  Prev: connector-j-usagenotes-statements,  Up: connector-j-usagenotes-basic

30.4.5.4 Using `CallableStatements' to Execute Stored Procedures
................................................................

Starting with MySQL server version 5.0 when used with Connector/J 3.1.1
or newer, the java.sql.CallableStatement interface is fully implemented
with the exception of the `getParameterMetaData()' method.

For more information on MySQL stored procedures, please refer to
`http://dev.mysql.com/doc/mysql/en/stored-procedures.html'.

Connector/J exposes stored procedure functionality through JDBC's
CallableStatement interface.

*Note*:

Current versions of MySQL server do not return enough information for
the JDBC driver to provide result set metadata for callable statements.
This means that when using `CallableStatement', `ResultSetMetaData' may
return `NULL'.

The following example shows a stored procedure that returns the value
of inOutParam incremented by 1, and the string passed in via inputParam
as a ResultSet:

     CREATE PROCEDURE demoSp(IN inputParam VARCHAR(255), \
                                             INOUT inOutParam INT)
     BEGIN
         DECLARE z INT;
         SET z = inOutParam + 1;
         SET inOutParam = z;

         SELECT inputParam;

         SELECT CONCAT('zyxw', inputParam);
     END

To use the `demoSp' procedure with Connector/J, follow these steps:

  1. Prepare the callable statement by using `Connection.prepareCall()'
     .

     Notice that you have to use JDBC escape syntax, and that the
     parentheses surrounding the parameter placeholders are not
     optional:

          import java.sql.CallableStatement;

          ...

              //
              // Prepare a call to the stored procedure 'demoSp'
              // with two parameters
              //
              // Notice the use of JDBC-escape syntax ({call ...})
              //

              CallableStatement cStmt = conn.prepareCall("{call demoSp(?, ?)}");

              cStmt.setString(1, "abcdefg");

     *Note*:

     `Connection.prepareCall()' is an expensive method, due to the
     metadata retrieval that the driver performs to support output
     parameters. For performance reasons, you should try to minimize
     unnecessary calls to `Connection.prepareCall()' by reusing
     CallableStatement instances in your code.

  2. Register the output parameters (if any exist)

     To retrieve the values of output parameters (parameters specified
     as `OUT' or `INOUT' when you created the stored procedure), JDBC
     requires that they be specified before statement execution using
     the various `registerOutputParameter()' methods in the
     CallableStatement interface:

          import java.sql.Types;
          ...
          //
          // Connector/J supports both named and indexed
          // output parameters. You can register output
          // parameters using either method, as well
          // as retrieve output parameters using either
          // method, regardless of what method was
          // used to register them.
          //
          // The following examples show how to use
          // the various methods of registering
          // output parameters (you should of course
          // use only one registration per parameter).
          //

          //
          // Registers the second parameter as output, and
          // uses the type 'INTEGER' for values returned from
          // getObject()
          //

          cStmt.registerOutParameter(2, Types.INTEGER);

          //
          // Registers the named parameter 'inOutParam', and
          // uses the type 'INTEGER' for values returned from
          // getObject()
          //

          cStmt.registerOutParameter("inOutParam", Types.INTEGER);
          ...

  3. Set the input parameters (if any exist)

     Input and in/out parameters are set as for PreparedStatement
     objects. However, CallableStatement also supports setting
     parameters by name:

          ...

              //
              // Set a parameter by index
              //

              cStmt.setString(1, "abcdefg");

              //
              // Alternatively, set a parameter using
              // the parameter name
              //

              cStmt.setString("inputParameter", "abcdefg");

              //
              // Set the 'in/out' parameter using an index
              //

              cStmt.setInt(2, 1);

              //
              // Alternatively, set the 'in/out' parameter
              // by name
              //

              cStmt.setInt("inOutParam", 1);

          ...

  4. Execute the CallableStatement, and retrieve any result sets or
     output parameters.

     Although CallableStatement supports calling any of the Statement
     execute methods (`executeUpdate()', `executeQuery()' or
     `execute()'), the most flexible method to call is `execute()', as
     you do not need to know ahead of time if the stored procedure
     returns result sets:

          ...

              boolean hadResults = cStmt.execute();

              //
              // Process all returned result sets
              //

              while (hadResults) {
                  ResultSet rs = cStmt.getResultSet();

                  // process result set
                  ...

                  hadResults = cStmt.getMoreResults();
              }

              //
              // Retrieve output parameters
              //
              // Connector/J supports both index-based and
              // name-based retrieval
              //

              int outputValue = cStmt.getInt(2); // index-based

              outputValue = cStmt.getInt("inOutParam"); // name-based

          ...


File: manual.info,  Node: connector-j-usagenotes-last-insert-id,  Prev: connector-j-usagenotes-statements-callable,  Up: connector-j-usagenotes-basic

30.4.5.5 Retrieving `AUTO_INCREMENT' Column Values
..................................................

Before version 3.0 of the JDBC API, there was no standard way of
retrieving key values from databases that supported auto increment or
identity columns. With older JDBC drivers for MySQL, you could always
use a MySQL-specific method on the Statement interface, or issue the
query `SELECT LAST_INSERT_ID()' after issuing an `INSERT' to a table
that had an `AUTO_INCREMENT' key. Using the MySQL-specific method call
isn't portable, and issuing a `SELECT' to get the `AUTO_INCREMENT'
key's value requires another round-trip to the database, which isn't as
efficient as possible. The following code snippets demonstrate the three
different ways to retrieve `AUTO_INCREMENT' values. First, we
demonstrate the use of the new JDBC-3.0 method `getGeneratedKeys()'
which is now the preferred method to use if you need to retrieve
`AUTO_INCREMENT' keys and have access to JDBC-3.0. The second example
shows how you can retrieve the same value using a standard `SELECT
LAST_INSERT_ID()' query. The final example shows how updatable result
sets can retrieve the `AUTO_INCREMENT' value when using the
`insertRow()' method.

        Statement stmt = null;
        ResultSet rs = null;

        try {

         //
         // Create a Statement instance that we can use for
         // 'normal' result sets assuming you have a
         // Connection 'conn' to a MySQL database already
         // available

         stmt = conn.createStatement(java.sql.ResultSet.TYPE_FORWARD_ONLY,
                                     java.sql.ResultSet.CONCUR_UPDATABLE);

         //
         // Issue the DDL queries for the table for this example
         //

         stmt.executeUpdate("DROP TABLE IF EXISTS autoIncTutorial");
         stmt.executeUpdate(
                 "CREATE TABLE autoIncTutorial ("
                 + "priKey INT NOT NULL AUTO_INCREMENT, "
                 + "dataField VARCHAR(64), PRIMARY KEY (priKey))");

         //
         // Insert one row that will generate an AUTO INCREMENT
         // key in the 'priKey' field
         //

         stmt.executeUpdate(
                 "INSERT INTO autoIncTutorial (dataField) "
                 + "values ('Can I Get the Auto Increment Field?')",
                 Statement.RETURN_GENERATED_KEYS);

         //
         // Example of using Statement.getGeneratedKeys()
         // to retrieve the value of an auto-increment
         // value
         //

         int autoIncKeyFromApi = -1;

         rs = stmt.getGeneratedKeys();

         if (rs.next()) {
             autoIncKeyFromApi = rs.getInt(1);
         } else {

             // throw an exception from here
         }

         rs.close();

         rs = null;

         System.out.println("Key returned from getGeneratedKeys():"
             + autoIncKeyFromApi);
     } finally {

         if (rs != null) {
             try {
                 rs.close();
             } catch (SQLException ex) {
                 // ignore
             }
         }

         if (stmt != null) {
             try {
                 stmt.close();
             } catch (SQLException ex) {
                 // ignore
             }
         }
     }

        Statement stmt = null;
        ResultSet rs = null;

        try {

         //
         // Create a Statement instance that we can use for
         // 'normal' result sets.

         stmt = conn.createStatement();

         //
         // Issue the DDL queries for the table for this example
         //

         stmt.executeUpdate("DROP TABLE IF EXISTS autoIncTutorial");
         stmt.executeUpdate(
                 "CREATE TABLE autoIncTutorial ("
                 + "priKey INT NOT NULL AUTO_INCREMENT, "
                 + "dataField VARCHAR(64), PRIMARY KEY (priKey))");

         //
         // Insert one row that will generate an AUTO INCREMENT
         // key in the 'priKey' field
         //

         stmt.executeUpdate(
                 "INSERT INTO autoIncTutorial (dataField) "
                 + "values ('Can I Get the Auto Increment Field?')");

         //
         // Use the MySQL LAST_INSERT_ID()
         // function to do the same thing as getGeneratedKeys()
         //

         int autoIncKeyFromFunc = -1;
         rs = stmt.executeQuery("SELECT LAST_INSERT_ID()");

         if (rs.next()) {
             autoIncKeyFromFunc = rs.getInt(1);
         } else {
             // throw an exception from here
         }

         rs.close();

         System.out.println("Key returned from " +
                            "'SELECT LAST_INSERT_ID()': " +
                            autoIncKeyFromFunc);

     } finally {

         if (rs != null) {
             try {
                 rs.close();
             } catch (SQLException ex) {
                 // ignore
             }
         }

         if (stmt != null) {
             try {
                 stmt.close();
             } catch (SQLException ex) {
                 // ignore
             }
         }
     }

        Statement stmt = null;
        ResultSet rs = null;

        try {

         //
         // Create a Statement instance that we can use for
         // 'normal' result sets as well as an 'updatable'
         // one, assuming you have a Connection 'conn' to
         // a MySQL database already available
         //

         stmt = conn.createStatement(java.sql.ResultSet.TYPE_FORWARD_ONLY,
                                     java.sql.ResultSet.CONCUR_UPDATABLE);

         //
         // Issue the DDL queries for the table for this example
         //

         stmt.executeUpdate("DROP TABLE IF EXISTS autoIncTutorial");
         stmt.executeUpdate(
                 "CREATE TABLE autoIncTutorial ("
                 + "priKey INT NOT NULL AUTO_INCREMENT, "
                 + "dataField VARCHAR(64), PRIMARY KEY (priKey))");

         //
         // Example of retrieving an AUTO INCREMENT key
         // from an updatable result set
         //

         rs = stmt.executeQuery("SELECT priKey, dataField "
            + "FROM autoIncTutorial");

         rs.moveToInsertRow();

         rs.updateString("dataField", "AUTO INCREMENT here?");
         rs.insertRow();

         //
         // the driver adds rows at the end
         //

         rs.last();

         //
         // We should now be on the row we just inserted
         //

         int autoIncKeyFromRS = rs.getInt("priKey");

         rs.close();

         rs = null;

         System.out.println("Key returned for inserted row: "
             + autoIncKeyFromRS);

     } finally {

         if (rs != null) {
             try {
                 rs.close();
             } catch (SQLException ex) {
                 // ignore
             }
         }

         if (stmt != null) {
             try {
                 stmt.close();
             } catch (SQLException ex) {
                 // ignore
             }
         }
     }

When you run the preceding example code, you should get the following
output: Key returned from `getGeneratedKeys()': 1 Key returned from
`SELECT LAST_INSERT_ID()': 1 Key returned for inserted row: 2 You
should be aware, that at times, it can be tricky to use the `SELECT
LAST_INSERT_ID()' query, as that function's value is scoped to a
connection. So, if some other query happens on the same connection, the
value will be overwritten. On the other hand, the `getGeneratedKeys()'
method is scoped by the Statement instance, so it can be used even if
other queries happen on the same connection, but not on the same
Statement instance.


File: manual.info,  Node: connector-j-usagenotes-j2ee,  Next: connector-j-usagenotes-troubleshooting,  Prev: connector-j-usagenotes-basic,  Up: connector-j-usagenotes

30.4.5.6 Using Connector/J with J2EE and Other Java Frameworks
..............................................................

* Menu:

* connector-j-usagenotes-j2ee-concepts::  General J2EE Concepts
* connector-j-usagenotes-tomcat::  Using Connector/J with Tomcat
* connector-j-usagenotes-jboss::  Using Connector/J with JBoss
* connector-j-usagenotes-spring-config::  Using Connector/J with Spring
* connector-j-usagenotes-glassfish-config::  Using Connector/J with GlassFish

This section describes how to use Connector/J in several contexts.


File: manual.info,  Node: connector-j-usagenotes-j2ee-concepts,  Next: connector-j-usagenotes-tomcat,  Prev: connector-j-usagenotes-j2ee,  Up: connector-j-usagenotes-j2ee

30.4.5.7 General J2EE Concepts
..............................

* Menu:

* connector-j-usagenotes-j2ee-concepts-connection-pooling::  Understanding Connection Pooling

This section provides general background on J2EE concepts that pertain
to use of Connector/J.


File: manual.info,  Node: connector-j-usagenotes-j2ee-concepts-connection-pooling,  Prev: connector-j-usagenotes-j2ee-concepts,  Up: connector-j-usagenotes-j2ee-concepts

30.4.5.8 Understanding Connection Pooling
.........................................

Connection pooling is a technique of creating and managing a pool of
connections that are ready for use by any thread that needs them.

This technique of pooling connections is based on the fact that most
applications only need a thread to have access to a JDBC connection
when they are actively processing a transaction, which usually take
only milliseconds to complete. When not processing a transaction, the
connection would otherwise sit idle. Instead, connection pooling allows
the idle connection to be used by some other thread to do useful work.

In practice, when a thread needs to do work against a MySQL or other
database with JDBC, it requests a connection from the pool. When the
thread is finished using the connection, it returns it to the pool, so
that it may be used by any other threads that want to use it.

When the connection is loaned out from the pool, it is used exclusively
by the thread that requested it. From a programming point of view, it
is the same as if your thread called `DriverManager.getConnection()'
every time it needed a JDBC connection, however with connection
pooling, your thread may end up using either a new, or already-existing
connection.

Connection pooling can greatly increase the performance of your Java
application, while reducing overall resource usage. The main benefits
to connection pooling are:

   * Reduced connection creation time

     Although this is not usually an issue with the quick connection
     setup that MySQL offers compared to other databases, creating new
     JDBC connections still incurs networking and JDBC driver overhead
     that will be avoided if connections are recycled.

   * Simplified programming model

     When using connection pooling, each individual thread can act as
     though it has created its own JDBC connection, allowing you to use
     straight-forward JDBC programming techniques.

   * Controlled resource usage

     If you don't use connection pooling, and instead create a new
     connection every time a thread needs one, your application's
     resource usage can be quite wasteful and lead to unpredictable
     behavior under load.

Remember that each connection to MySQL has overhead (memory, CPU,
context switches, and so forth) on both the client and server side.
Every connection limits how many resources there are available to your
application as well as the MySQL server. Many of these resources will
be used whether or not the connection is actually doing any useful work!

Connection pools can be tuned to maximize performance, while keeping
resource utilization below the point where your application will start
to fail rather than just run slower.

Luckily, Sun has standardized the concept of connection pooling in JDBC
through the JDBC-2.0 Optional interfaces, and all major application
servers have implementations of these APIs that work fine with MySQL
Connector/J.

Generally, you configure a connection pool in your application server
configuration files, and access it via the Java Naming and Directory
Interface (JNDI). The following code shows how you might use a
connection pool from an application deployed in a J2EE application
server:

     import java.sql.Connection;
     import java.sql.SQLException;
     import java.sql.Statement;

     import javax.naming.InitialContext;
     import javax.sql.DataSource;

     public class MyServletJspOrEjb {

         public void doSomething() throws Exception {
             /*
              * Create a JNDI Initial context to be able to
              *  lookup  the DataSource
              *
              * In production-level code, this should be cached as
              * an instance or static variable, as it can
              * be quite expensive to create a JNDI context.
              *
              * Note: This code only works when you are using servlets
              * or EJBs in a J2EE application server. If you are
              * using connection pooling in standalone Java code, you
              * will have to create/configure datasources using whatever
              * mechanisms your particular connection pooling library
              * provides.
              */

             InitialContext ctx = new InitialContext();

              /*
               * Lookup the DataSource, which will be backed by a pool
               * that the application server provides. DataSource instances
               * are also a good candidate for caching as an instance
               * variable, as JNDI lookups can be expensive as well.
               */

             DataSource ds =
               (DataSource)ctx.lookup("java:comp/env/jdbc/MySQLDB");

             /*
              * The following code is what would actually be in your
              * Servlet, JSP or EJB 'service' method...where you need
              * to work with a JDBC connection.
              */

             Connection conn = null;
             Statement stmt = null;

             try {
                 conn = ds.getConnection();

                 /*
                  * Now, use normal JDBC programming to work with
                  * MySQL, making sure to close each resource when you're
                  * finished with it, which allows the connection pool
                  * resources to be recovered as quickly as possible
                  */

                 stmt = conn.createStatement();
                 stmt.execute("SOME SQL QUERY");

                 stmt.close();
                 stmt = null;

                 conn.close();
                 conn = null;
             } finally {
                 /*
                  * close any jdbc instances here that weren't
                  * explicitly closed during normal code path, so
                  * that we don't 'leak' resources...
                  */

                 if (stmt != null) {
                     try {
                         stmt.close();
                     } catch (sqlexception sqlex) {
                         // ignore -- as we can't do anything about it here
                     }

                     stmt = null;
                 }

                 if (conn != null) {
                     try {
                         conn.close();
                     } catch (sqlexception sqlex) {
                         // ignore -- as we can't do anything about it here
                     }

                     conn = null;
                 }
             }
         }
     }

As shown in the example above, after obtaining the JNDI InitialContext,
and looking up the DataSource, the rest of the code should look
familiar to anyone who has done JDBC programming in the past.

The most important thing to remember when using connection pooling is
to make sure that no matter what happens in your code (exceptions,
flow-of-control, and so forth), connections, and anything created by
them (such as statements or result sets) are closed, so that they may be
re-used, otherwise they will be stranded, which in the best case means
that the MySQL server resources they represent (such as buffers, locks,
or sockets) may be tied up for some time, or worst case, may be tied up
forever.

What's the Best Size for my Connection Pool?

As with all other configuration rules-of-thumb, the answer is: it
depends. Although the optimal size depends on anticipated load and
average database transaction time, the optimum connection pool size is
smaller than you might expect. If you take Sun's Java Petstore blueprint
application for example, a connection pool of 15-20 connections can
serve a relatively moderate load (600 concurrent users) using MySQL and
Tomcat with response times that are acceptable.

To correctly size a connection pool for your application, you should
create load test scripts with tools such as Apache JMeter or The
Grinder, and load test your application.

An easy way to determine a starting point is to configure your
connection pool's maximum number of connections to be unbounded, run a
load test, and measure the largest amount of concurrently used
connections. You can then work backward from there to determine what
values of minimum and maximum pooled connections give the best
performance for your particular application.


File: manual.info,  Node: connector-j-usagenotes-tomcat,  Next: connector-j-usagenotes-jboss,  Prev: connector-j-usagenotes-j2ee-concepts,  Up: connector-j-usagenotes-j2ee

30.4.5.9 Using Connector/J with Tomcat
......................................

The following instructions are based on the instructions for
Tomcat-5.x, available at
`http://tomcat.apache.org/tomcat-5.5-doc/jndi-datasource-examples-howto.html'
which is current at the time this document was written.

First, install the .jar file that comes with Connector/J in
`$CATALINA_HOME/common/lib' so that it is available to all applications
installed in the container.

Next, Configure the JNDI DataSource by adding a declaration resource to
`$CATALINA_HOME/conf/server.xml' in the context that defines your web
application:

     <Context ....>

       ...

       <Resource name="jdbc/MySQLDB"
                    auth="Container"
                    type="javax.sql.DataSource"/>

       <!-- The name you used above, must match _exactly_ here!

            The connection pool will be bound into JNDI with the name
            "java:/comp/env/jdbc/MySQLDB"
       -->

       <ResourceParams name="jdbc/MySQLDB">
         <parameter>
           <name>factory</name>
           <value>org.apache.commons.dbcp.BasicDataSourceFactory</value>
         </parameter>

         <!-- Don't set this any higher than max_connections on your
              MySQL server, usually this should be a 10 or a few 10's
              of connections, not hundreds or thousands -->

         <parameter>
           <name>maxActive</name>
           <value>10</value>
         </parameter>

         <!-- You don't want to many idle connections hanging around
              if you can avoid it, only enough to soak up a spike in
              the load -->

         <parameter>
           <name>maxIdle</name>
           <value>5</value>
         </parameter>

         <!-- Don't use autoReconnect=true, it's going away eventually
              and it's a crutch for older connection pools that couldn't
              test connections. You need to decide whether your application
              is supposed to deal with SQLExceptions (hint, it should), and
              how much of a performance penalty you're willing to pay
              to ensure 'freshness' of the connection -->

         <parameter>
           <name>validationQuery</name>
           <value>SELECT 1</value>
         </parameter>

        <!-- The most conservative approach is to test connections
             before they're given to your application. For most applications
             this is okay, the query used above is very small and takes
             no real server resources to process, other than the time used
             to traverse the network.

             If you have a high-load application you'll need to rely on
             something else. -->

         <parameter>
           <name>testOnBorrow</name>
           <value>true</value>
         </parameter>

        <!-- Otherwise, or in addition to testOnBorrow, you can test
             while connections are sitting idle -->

         <parameter>
           <name>testWhileIdle</name>
           <value>true</value>
         </parameter>

         <!-- You have to set this value, otherwise even though
              you've asked connections to be tested while idle,
              the idle evicter thread will never run -->

         <parameter>
           <name>timeBetweenEvictionRunsMillis</name>
           <value>10000</value>
         </parameter>

         <!-- Don't allow connections to hang out idle too long,
              never longer than what wait_timeout is set to on the
              server...A few minutes or even fraction of a minute
              is sometimes okay here, it depends on your application
              and how much spikey load it will see -->

         <parameter>
           <name>minEvictableIdleTimeMillis</name>
           <value>60000</value>
         </parameter>

         <!-- Username and password used when connecting to MySQL -->

         <parameter>
          <name>username</name>
          <value>someuser</value>
         </parameter>

         <parameter>
          <name>password</name>
          <value>somepass</value>
         </parameter>

         <!-- Class name for the Connector/J driver -->

         <parameter>
            <name>driverClassName</name>
            <value>com.mysql.jdbc.Driver</value>
         </parameter>

         <!-- The JDBC connection url for connecting to MySQL, notice
              that if you want to pass any other MySQL-specific parameters
              you should pass them here in the URL, setting them using the
              parameter tags above will have no effect, you will also
              need to use &amp; to separate parameter values as the
              ampersand is a reserved character in XML -->

         <parameter>
           <name>url</name>
           <value>jdbc:mysql://localhost:3306/test</value>
         </parameter>

       </ResourceParams>
     </Context>

In general, you should follow the installation instructions that come
with your version of Tomcat, as the way you configure datasources in
Tomcat changes from time-to-time, and unfortunately if you use the
wrong syntax in your XML file, you will most likely end up with an
exception similar to the following:

     Error: java.sql.SQLException: Cannot load JDBC driver class 'null ' SQL
     state: null


File: manual.info,  Node: connector-j-usagenotes-jboss,  Next: connector-j-usagenotes-spring-config,  Prev: connector-j-usagenotes-tomcat,  Up: connector-j-usagenotes-j2ee

30.4.5.10 Using Connector/J with JBoss
......................................

These instructions cover JBoss-4.x. To make the JDBC driver classes
available to the application server, copy the .jar file that comes with
Connector/J to the `lib' directory for your server configuration (which
is usually called `default'). Then, in the same configuration
directory, in the subdirectory named deploy, create a datasource
configuration file that ends with "-ds.xml", which tells JBoss to
deploy this file as a JDBC Datasource. The file should have the
following contents:

     <datasources>
         <local-tx-datasource>
             <!-- This connection pool will be bound into JNDI with the name
                  "java:/MySQLDB" -->

             <jndi-name>MySQLDB</jndi-name>
             <connection-url>jdbc:mysql://localhost:3306/dbname</connection-url>
             <driver-class>com.mysql.jdbc.Driver</driver-class>
             <user-name>user</user-name>
             <password>pass</password>

             <min-pool-size>5</min-pool-size>

             <!-- Don't set this any higher than max_connections on your
              MySQL server, usually this should be a 10 or a few 10's
              of connections, not hundreds or thousands -->

             <max-pool-size>20</max-pool-size>

             <!-- Don't allow connections to hang out idle too long,
              never longer than what wait_timeout is set to on the
              server...A few minutes is usually okay here,
              it depends on your application
              and how much spikey load it will see -->

             <idle-timeout-minutes>5</idle-timeout-minutes>

             <!-- If you're using Connector/J 3.1.8 or newer, you can use
                  our implementation of these to increase the robustness
                  of the connection pool. -->

             <exception-sorter-class-name>
       com.mysql.jdbc.integration.jboss.ExtendedMysqlExceptionSorter
             </exception-sorter-class-name>
             <valid-connection-checker-class-name>
       com.mysql.jdbc.integration.jboss.MysqlValidConnectionChecker
             </valid-connection-checker-class-name>

         </local-tx-datasource>
     </datasources>


File: manual.info,  Node: connector-j-usagenotes-spring-config,  Next: connector-j-usagenotes-glassfish-config,  Prev: connector-j-usagenotes-jboss,  Up: connector-j-usagenotes-j2ee

30.4.5.11 Using Connector/J with Spring
.......................................

* Menu:

* connector-j-usagenotes-spring-config-jdbctemplate::  Using JdbcTemplate
* connector-j-usagenotes-spring-config-transactional::  Transactional JDBC Access
* connector-j-usagenotes-spring-config-connpooling::  Connection Pooling

The Spring Framework is a Java-based application framework designed for
assisting in application design by providing a way to configure
components. The technique used by Spring is a well known design pattern
called Dependency Injection (see Inversion of Control Containers and
the Dependency Injection pattern
(http://www.martinfowler.com/articles/injection.html)). This article
will focus on Java-oriented access to MySQL databases with Spring 2.0.
For those wondering, there is a .NET port of Spring appropriately named
Spring.NET.

Spring is not only a system for configuring components, but also
includes support for aspect oriented programming (AOP).  This is one of
the main benefits and the foundation for Spring's resource and
transaction management. Spring also provides utilities for integrating
resource management with JDBC and Hibernate.

For the examples in this section the MySQL world sample database will
be used. The first task is to set up a MySQL data source through
Spring. Components within Spring use the "bean" terminology. For
example, to configure a connection to a MySQL server supporting the
world sample database you might use:

     <util:map id="dbProps">
         <entry key="db.driver" value="com.mysql.jdbc.Driver"/>
         <entry key="db.jdbcurl" value="jdbc:mysql://localhost/world"/>
         <entry key="db.username" value="myuser"/>
         <entry key="db.password" value="mypass"/>
     </util:map>

In the above example we are assigning values to properties that will be
used in the configuration. For the datasource configuration:

     <bean id="dataSource"
            class="org.springframework.jdbc.datasource.DriverManagerDataSource">
         <property name="driverClassName" value="${db.driver}"/>
         <property name="url" value="${db.jdbcurl}"/>
         <property name="username" value="${db.username}"/>
         <property name="password" value="${db.password}"/>
     </bean>

The placeholders are used to provide values for properties of this
bean. This means that you can specify all the properties of the
configuration in one place instead of entering the values for each
property on each bean. We do, however, need one more bean to pull this
all together. The last bean is responsible for actually replacing the
placeholders with the property values.

     <bean
      class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
         <property name="properties" ref="dbProps"/>
     </bean>

Now that we have our MySQL data source configured and ready to go, we
write some Java code to access it. The example below will retrieve
three random cities and their corresponding country using the data
source we configured with Spring.

     // Create a new application context. this processes the Spring config
     ApplicationContext ctx =
         new ClassPathXmlApplicationContext("ex1appContext.xml");
     // Retrieve the data source from the application context
         DataSource ds = (DataSource) ctx.getBean("dataSource");
     // Open a database connection using Spring's DataSourceUtils
     Connection c = DataSourceUtils.getConnection(ds);
     try {
         // retrieve a list of three random cities
         PreparedStatement ps = c.prepareStatement(
             "select City.Name as 'City', Country.Name as 'Country' " +
             "from City inner join Country on City.CountryCode = Country.Code " +
             "order by rand() limit 3");
         ResultSet rs = ps.executeQuery();
         while(rs.next()) {
             String city = rs.getString("City");
             String country = rs.getString("Country");
             System.out.printf("The city %s is in %s%n", city, country);
         }
     } catch (SQLException ex) {
         // something has failed and we print a stack trace to analyse the error
         ex.printStackTrace();
         // ignore failure closing connection
         try { c.close(); } catch (SQLException e) { }
     } finally {
         // properly release our connection
         DataSourceUtils.releaseConnection(c, ds);
     }

This is very similar to normal JDBC access to MySQL with the main
difference being that we are using DataSourceUtils instead of the
DriverManager to create the connection.

While it may seem like a small difference, the implications are
somewhat far reaching. Spring manages this resource in a way similar to
a container managed data source in a J2EE application server. When a
connection is opened, it can be subsequently accessed in other parts of
the code if it is synchronized with a transaction. This makes it
possible to treat different parts of your application as transactional
instead of passing around a database connection.


File: manual.info,  Node: connector-j-usagenotes-spring-config-jdbctemplate,  Next: connector-j-usagenotes-spring-config-transactional,  Prev: connector-j-usagenotes-spring-config,  Up: connector-j-usagenotes-spring-config

30.4.5.12 Using JdbcTemplate
............................

Spring makes extensive use of the Template method design pattern (see
Template Method Pattern
(http://en.wikipedia.org/wiki/Template_method_pattern)). Our immediate
focus will be on the `JdbcTemplate' and related classes, specifically
`NamedParameterJdbcTemplate'.  The template classes handle obtaining
and releasing a connection for data access when one is needed.

The next example shows how to use `NamedParameterJdbcTemplate' inside
of a DAO (Data Access Object) class to retrieve a random city given a
country code.

     public class Ex2JdbcDao {
          /**
          * Data source reference which will be provided by Spring.
          */
          private DataSource dataSource;

          /**
          * Our query to find a random city given a country code. Notice
          * the ":country" parameter towards the end. This is called a
          * named parameter.
          */
          private String queryString = "select Name from City " +
             "where CountryCode = :country order by rand() limit 1";

          /**
          * Retrieve a random city using Spring JDBC access classes.
          */
          public String getRandomCityByCountryCode(String cntryCode) {
              // A template that allows using queries with named parameters
              NamedParameterJdbcTemplate template =
              new NamedParameterJdbcTemplate(dataSource);
              // A java.util.Map is used to provide values for the parameters
              Map params = new HashMap();
              params.put("country", cntryCode);
              // We query for an Object and specify what class we are expecting
              return (String)template.queryForObject(queryString, params, String.class);
          }

         /**
         * A JavaBean setter-style method to allow Spring to inject the data source.
         * @param dataSource
         */
         public void setDataSource(DataSource dataSource) {
             this.dataSource = dataSource;
         }
     }

The focus in the above code is on the `getRandomCityByCountryCode()'
method. We pass a country code and use the `NamedParameterJdbcTemplate'
to query for a city. The country code is placed in a Map with the key
"country", which is the parameter is named in the SQL query.

To access this code, you need to configure it with Spring by providing
a reference to the data source.

     <bean id="dao" class="code.Ex2JdbcDao">
         <property name="dataSource" ref="dataSource"/>
     </bean>

At this point, we can just grab a reference to the DAO from Spring and
call `getRandomCityByCountryCode()'.

     // Create the application context
         ApplicationContext ctx =
         new ClassPathXmlApplicationContext("ex2appContext.xml");
         // Obtain a reference to our DAO
         Ex2JdbcDao dao = (Ex2JdbcDao) ctx.getBean("dao");

         String countryCode = "USA";

         // Find a few random cities in the US
         for(int i = 0; i < 4; ++i)
             System.out.printf("A random city in %s is %s%n", countryCode,
                 dao.getRandomCityByCountryCode(countryCode));

This example shows how to use Spring's JDBC classes to completely
abstract away the use of traditional JDBC classes including
`Connection' and `PreparedStatement'.


File: manual.info,  Node: connector-j-usagenotes-spring-config-transactional,  Next: connector-j-usagenotes-spring-config-connpooling,  Prev: connector-j-usagenotes-spring-config-jdbctemplate,  Up: connector-j-usagenotes-spring-config

30.4.5.13 Transactional JDBC Access
...................................

You might be wondering how we can add transactions into our code if we
don't deal directly with the JDBC classes. Spring provides a
transaction management package that not only replaces JDBC transaction
management, but also allows declarative transaction management
(configuration instead of code).

In order to use transactional database access, we will need to change
the storage engine of the tables in the world database. The downloaded
script explicitly creates MyISAM tables which do not support
transactional semantics. The InnoDB storage engine does support
transactions and this is what we will be using. We can change the
storage engine with the following statements.

     ALTER TABLE City ENGINE=InnoDB;
     ALTER TABLE Country ENGINE=InnoDB;
     ALTER TABLE CountryLanguage ENGINE=InnoDB;

A good programming practice emphasized by Spring is separating
interfaces and implementations. What this means is that we can create a
Java interface and only use the operations on this interface without
any internal knowledge of what the actual implementation is. We will
let Spring manage the implementation and with this it will manage the
transactions for our implementation.

First you create a simple interface:

     public interface Ex3Dao {
         Integer createCity(String name, String countryCode,
         String district, Integer population);
     }

This interface contains one method that will create a new city record
in the database and return the id of the new record. Next you need to
create an implementation of this interface.

     public class Ex3DaoImpl implements Ex3Dao {
         protected DataSource dataSource;
         protected SqlUpdate updateQuery;
         protected SqlFunction idQuery;

         public Integer createCity(String name, String countryCode,
             String district, Integer population) {
                 updateQuery.update(new Object[] { name, countryCode,
                        district, population });
                 return getLastId();
             }

         protected Integer getLastId() {
             return idQuery.run();
         }
     }

You can see that we only operate on abstract query objects here and
don't deal directly with the JDBC API. Also, this is the complete
implementation. All of our transaction management will be dealt with in
the configuration. To get the configuration started, we need to create
the DAO.

     <bean id="dao" class="code.Ex3DaoImpl">
         <property name="dataSource" ref="dataSource"/>
         <property name="updateQuery">...</property>
         <property name="idQuery">...</property>
     </bean>

Now you need to set up the transaction configuration. The first thing
you must do is create transaction manager to manage the data source and
a specification of what transaction properties are required for for the
`dao' methods.

     <bean id="transactionManager"
       class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
         <property name="dataSource" ref="dataSource"/>
     </bean>

     <tx:advice id="txAdvice" transaction-manager="transactionManager">
         <tx:attributes>
             <tx:method name="*"/>
         </tx:attributes>
     </tx:advice>

The preceding code creates a transaction manager that handles
transactions for the data source provided to it. The `txAdvice' uses
this transaction manager and the attributes specify to create a
transaction for all methods. Finally you need to apply this advice with
an AOP pointcut.

     <aop:config>
         <aop:pointcut id="daoMethods"
             expression="execution(* code.Ex3Dao.*(..))"/>
          <aop:advisor advice-ref="txAdvice" pointcut-ref="daoMethods"/>
     </aop:config>

This basically says that all methods called on the `Ex3Dao' interface
will be wrapped in a transaction. To make use of this, you only have to
retrieve the `dao' from the application context and call a method on
the `dao' instance.

     Ex3Dao dao = (Ex3Dao) ctx.getBean("dao");
     Integer id = dao.createCity(name,  countryCode, district, pop);

We can verify from this that there is no transaction management
happening in our Java code and it's all configured with Spring. This is
a very powerful notion and regarded as one of the most beneficial
features of Spring.


File: manual.info,  Node: connector-j-usagenotes-spring-config-connpooling,  Prev: connector-j-usagenotes-spring-config-transactional,  Up: connector-j-usagenotes-spring-config

30.4.5.14 Connection Pooling
............................

In many sitations, such as web applications, there will be a large
number of small database transactions. When this is the case, it
usually makes sense to create a pool of database connections available
for web requests as needed.  Although MySQL does not spawn an extra
process when a connection is made, there is still a small amount of
overhead to create and set up the connection. Pooling of connections
also alleviates problems such as collecting large amounts of sockets in
the `TIME_WAIT' state.

Setting up pooling of MySQL connections with Spring is as simple as
changing the data source configuration in the application context.
There are a number of configurations that we can use. The first example
is based on the Jakarta Commons DBCP library
(http://jakarta.apache.org/commons/dbcp/). The example below replaces
the source configuration that was based on `DriverManagerDataSource'
with DBCP's BasicDataSource.

     <bean id="dataSource" destroy-method="close"
       class="org.apache.commons.dbcp.BasicDataSource">
         <property name="driverClassName" value="${db.driver}"/>
         <property name="url" value="${db.jdbcurl}"/>
         <property name="username" value="${db.username}"/>
         <property name="password" value="${db.password}"/>
         <property name="initialSize" value="3"/>
     </bean>

The configuration of the two solutions is very similar. The difference
is that DBCP will pool connections to the database instead of creating
a new connection every time one is requested. We have also set a
parameter here called `initialSize'. This tells DBCP that we want three
connections in the pool when it is created.

Another way to configure connection pooling is to configure a data
source in our J2EE application server. Using JBoss as an example, you
can set up the MySQL connection pool by creating a file called
`mysql-local-ds.xml' and placing it in the server/default/deploy
directory in JBoss. Once we have this setup, we can use JNDI to look it
up. With Spring, this lookup is very simple. The data source
configuration looks like this.

     <jee:jndi-lookup id="dataSource" jndi-name="java:MySQL_DS"/>


File: manual.info,  Node: connector-j-usagenotes-glassfish-config,  Prev: connector-j-usagenotes-spring-config,  Up: connector-j-usagenotes-j2ee

30.4.5.15 Using Connector/J with GlassFish
..........................................


File: manual.info,  Node: connector-j-usagenotes-troubleshooting,  Prev: connector-j-usagenotes-j2ee,  Up: connector-j-usagenotes

30.4.5.16 Common Problems and Solutions
.......................................

There are a few issues that seem to be commonly encountered often by
users of MySQL Connector/J. This section deals with their symptoms, and
their resolutions.

*Questions*
   * 31.4.5.3.1: When I try to connect to the database with MySQL
     Connector/J, I get the following exception:

          SQLException: Server configuration denies access to data source
          SQLState: 08001
          VendorError: 0

     What's going on? I can connect just fine with the MySQL
     command-line client.

   * 31.4.5.3.2: My application throws an SQLException 'No Suitable
     Driver'. Why is this happening?

   * 31.4.5.3.3: I'm trying to use MySQL Connector/J in an applet or
     application and I get an exception similar to:

          SQLException: Cannot connect to MySQL server on host:3306.
          Is there a MySQL server running on the machine/port you
          are trying to connect to?

          (java.security.AccessControlException)
          SQLState: 08S01
          VendorError: 0

   * 31.4.5.3.4: I have a servlet/application that works fine for a day,
     and then stops working overnight

   * 31.4.5.3.5: I'm trying to use JDBC-2.0 updatable result sets, and I
     get an exception saying my result set is not updatable.

   * 31.4.5.3.6: I cannot connect to the MySQL server using Connector/J,
     and I'm sure the connection paramters are correct.

   * 31.4.5.3.7: I am trying to connect to my MySQL server within my
     application, but I get the following error and stack trace:

          java.net.SocketException
          MESSAGE: Software caused connection abort: recv failed

          STACKTRACE:

          java.net.SocketException: Software caused connection abort: recv failed
          at java.net.SocketInputStream.socketRead0(Native Method)
          at java.net.SocketInputStream.read(Unknown Source)
          at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1392)
          at com.mysql.jdbc.MysqlIO.readPacket(MysqlIO.java:1414)
          at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:625)
          at com.mysql.jdbc.Connection.createNewIO(Connection.java:1926)
          at com.mysql.jdbc.Connection.<init>(Connection.java:452)
          at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:411)

   * 31.4.5.3.8: My application is deployed through JBoss and I am using
     transactions to handle the statements on the MySQL database. Under
     heavy loads I am getting a error and stack trace, but these only
     occur after a fixed period of heavy activity.

   * 31.4.5.3.9: When using `gcj' an `java.io.CharConversionException'
     is raised when working with certain character sequences.

   * 31.4.5.3.10: Updating a table that contains a primary key that is
     either `FLOAT' or compound primary key that uses `FLOAT' fails to
     update the table and raises an exception.

*Questions and Answers* *31.4.5.3.1: ** When I try to connect to the
database with MySQL Connector/J, I get the following exception: *
     SQLException: Server configuration denies access to data source
     SQLState: 08001
     VendorError: 0
* What's going on? I can connect just fine with the MySQL command-line
client.  *

MySQL Connector/J must use TCP/IP sockets to connect to MySQL, as Java
does not support Unix Domain Sockets.  Therefore, when MySQL
Connector/J connects to MySQL, the security manager in MySQL server
will use its grant tables to determine whether the connection should be
allowed.

You must add the necessary security credentials to the MySQL server for
this to happen, using the `GRANT' statement to your MySQL Server.  See
*Note grant::, for more information.

*Note*:

Testing your connectivity with the `mysql' command-line client will not
work unless you add the `--host' flag, and use something other than
`localhost' for the host. The `mysql' command-line client will use Unix
domain sockets if you use the special hostname `localhost'. If you are
testing connectivity to `localhost', use `127.0.0.1' as the hostname
instead.

*Warning*:

Changing privileges and permissions improperly in MySQL can potentially
cause your server installation to not have optimal security properties.

*31.4.5.3.2: ** My application throws an SQLException 'No Suitable
Driver'. Why is this happening?  *

There are three possible causes for this error:

   * The Connector/J driver is not in your `CLASSPATH', see *Note
     connector-j-installing::.

   * The format of your connection URL is incorrect, or you are
     referencing the wrong JDBC driver.

   * When using DriverManager, the `jdbc.drivers' system property has
     not been populated with the location of the Connector/J driver.

*31.4.5.3.3: ** I'm trying to use MySQL Connector/J in an applet or
application and I get an exception similar to: *
     SQLException: Cannot connect to MySQL server on host:3306.
     Is there a MySQL server running on the machine/port you
     are trying to connect to?

     (java.security.AccessControlException)
     SQLState: 08S01
     VendorError: 0

Either you're running an Applet, your MySQL server has been installed
with the "-skip-networking" option set, or your MySQL server has a
firewall sitting in front of it.

Applets can only make network connections back to the machine that runs
the web server that served the .class files for the applet. This means
that MySQL must run on the same machine (or you must have some sort of
port re-direction) for this to work. This also means that you will not
be able to test applets from your local file system, you must always
deploy them to a web server.

MySQL Connector/J can only communicate with MySQL using TCP/IP, as Java
does not support Unix domain sockets.  TCP/IP communication with MySQL
might be affected if MySQL was started with the "-skip-networking"
flag, or if it is firewalled.

If MySQL has been started with the "-skip-networking" option set (the
Debian Linux package of MySQL server does this for example), you need
to comment it out in the file /etc/mysql/my.cnf or /etc/my.cnf. Of
course your my.cnf file might also exist in the `data' directory of
your MySQL server, or anywhere else (depending on how MySQL was
compiled for your system).  Binaries created by MySQL AB always look in
/etc/my.cnf and [datadir]/my.cnf. If your MySQL server has been
firewalled, you will need to have the firewall configured to allow
TCP/IP connections from the host where your Java code is running to the
MySQL server on the port that MySQL is listening to (by default, 3306).

*31.4.5.3.4: ** I have a servlet/application that works fine for a day,
and then stops working overnight *

MySQL closes connections after 8 hours of inactivity. You either need
to use a connection pool that handles stale connections or use the
"autoReconnect" parameter (see *Note
connector-j-reference-configuration-properties::).

Also, you should be catching SQLExceptions in your application and
dealing with them, rather than propagating them all the way until your
application exits, this is just good programming practice. MySQL
Connector/J will set the SQLState (see
`java.sql.SQLException.getSQLState()' in your APIDOCS) to "08S01" when
it encounters network-connectivity issues during the processing of a
query. Your application code should then attempt to re-connect to MySQL
at this point.

The following (simplistic) example shows what code that can handle
these exceptions might look like:

     public void doBusinessOp() throws SQLException {
         Connection conn = null;
         Statement stmt = null;
         ResultSet rs = null;

         //
         // How many times do you want to retry the transaction
         // (or at least _getting_ a connection)?
         //
         int retryCount = 5;

         boolean transactionCompleted = false;

         do {
             try {
                 conn = getConnection(); // assume getting this from a
                                         // javax.sql.DataSource, or the
                                         // java.sql.DriverManager

                 conn.setAutoCommit(false);

                 //
                 // Okay, at this point, the 'retry-ability' of the
                 // transaction really depends on your application logic,
                 // whether or not you're using autocommit (in this case
                 // not), and whether you're using transacational storage
                 // engines
                 //
                 // For this example, we'll assume that it's _not_ safe
                 // to retry the entire transaction, so we set retry
                 // count to 0 at this point
                 //
                 // If you were using exclusively transaction-safe tables,
                 // or your application could recover from a connection going
                 // bad in the middle of an operation, then you would not
                 // touch 'retryCount' here, and just let the loop repeat
                 // until retryCount == 0.
                 //
                 retryCount = 0;

                 stmt = conn.createStatement();

                 String query = "SELECT foo FROM bar ORDER BY baz";

                 rs = stmt.executeQuery(query);

                 while (rs.next()) {
                 }

                 rs.close();
                 rs = null;

                 stmt.close();
                 stmt = null;

                 conn.commit();
                 conn.close();
                 conn = null;

                 transactionCompleted = true;
             } catch (SQLException sqlEx) {

                 //
                 // The two SQL states that are 'retry-able' are 08S01
                 // for a communications error, and 40001 for deadlock.
                 //
                 // Only retry if the error was due to a stale connection,
                 // communications problem or deadlock
                 //

                 String sqlState = sqlEx.getSQLState();

                 if ("08S01".equals(sqlState) || "40001".equals(sqlState)) {
                     retryCount--;
                 } else {
                     retryCount = 0;
                 }
             } finally {
                 if (rs != null) {
                     try {
                         rs.close();
                     } catch (SQLException sqlEx) {
                         // You'd probably want to log this . . .
                     }
                 }

                 if (stmt != null) {
                     try {
                         stmt.close();
                     } catch (SQLException sqlEx) {
                         // You'd probably want to log this as well . . .
                     }
                 }

                 if (conn != null) {
                     try {
                         //
                         // If we got here, and conn is not null, the
                         // transaction should be rolled back, as not
                         // all work has been done

                         try {
                             conn.rollback();
                         } finally {
                             conn.close();
                         }
                     } catch (SQLException sqlEx) {
                         //
                         // If we got an exception here, something
                         // pretty serious is going on, so we better
                         // pass it up the stack, rather than just
                         // logging it. . .

                         throw sqlEx;
                     }
                 }
             }
         } while (!transactionCompleted && (retryCount > 0));
     }

*Note*:

Use of the `autoReconnect' option is not recommended because there is
no safe method of reconnecting to the MySQL server without risking some
corruption of the connection state or database state information.
Instead, you should use a connection pool which will enable your
application to connect to the MySQL server using an available
connection from the pool. The `autoReconnect' facility is deprecated,
and may be removed in a future release.

*31.4.5.3.5: ** I'm trying to use JDBC-2.0 updatable result sets, and I
get an exception saying my result set is not updatable.  *

Because MySQL does not have row identifiers, MySQL Connector/J can only
update result sets that have come from queries on tables that have at
least one primary key, the query must select every primary key and the
query can only span one table (that is, no joins). This is outlined in
the JDBC specification.

Note that this issue only occurs when using updatable result sets, and
is caused because Connector/J is unable to guarantee that it can
identify the correct rows within the result set to be updated without
having a unique reference to each row. There is no requirement to have a
unique field on a table if you are using `UPDATE' or `DELETE'
statements on a table where you can individually specify the criteria
to be matched using a `WHERE' clause.

*31.4.5.3.6: ** I cannot connect to the MySQL server using Connector/J,
and I'm sure the connection paramters are correct.  *

Make sure that the `skip-networking' option has not been enabled on
your server. Connector/J must be able to communicate with your server
over TCP/IP, named sockets are not supported. Also ensure that you are
not filtering connections through a Firewall or other network security
system. For more informaiton, see *Note can-not-connect-to-server::.

*31.4.5.3.7: ** I am trying to connect to my MySQL server within my
application, but I get the following error and stack trace: *
     java.net.SocketException
     MESSAGE: Software caused connection abort: recv failed

     STACKTRACE:

     java.net.SocketException: Software caused connection abort: recv failed
     at java.net.SocketInputStream.socketRead0(Native Method)
     at java.net.SocketInputStream.read(Unknown Source)
     at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1392)
     at com.mysql.jdbc.MysqlIO.readPacket(MysqlIO.java:1414)
     at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:625)
     at com.mysql.jdbc.Connection.createNewIO(Connection.java:1926)
     at com.mysql.jdbc.Connection.<init>(Connection.java:452)
     at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:411)

The error probably indicates that you are using a older version of the
Connector/J JDBC driver (2.0.14 or 3.0.x) and you are trying to connect
to a MySQL server with version 4.1x or newer. The older drivers are not
compatible with 4.1 or newer of MySQL as they do not support the newer
authentication mechanisms.

It is likely that the older version of the Connector/J driver exists
within your application directory or your `CLASSPATH' includes the older
Connector/J package.

*31.4.5.3.8: ** My application is deployed through JBoss and I am using
transactions to handle the statements on the MySQL database. Under
heavy loads I am getting a error and stack trace, but these only occur
after a fixed period of heavy activity.  *

This is a JBoss, not Connector/J, issue and is connected to the use of
transactions. Under heavy loads the time taken for transactions to
complete can increase, and the error is caused because you have
exceeded the predefined timeout.

You can increase the timeout value by setting the `TransactionTimeout'
attribute to the `TransactionManagerService' within the
`/conf/jboss-service.xml' file (pre-4.0.3) or `/deploy/jta-service.xml'
for JBoss 4.0.3 or later. See TransactionTimeoute
(http://wiki.jboss.org/wiki/Wiki.jsp?page=TransactionTimeout) within
the JBoss wiki for more information.

*31.4.5.3.9: ** When using `gcj' an `java.io.CharConversionException' is
raised when working with certain character sequences.  *

This is a known issue with `gcj' which raises an exception when it
reaches an unknown character or one it cannot convert. You should add
`useJvmCharsetConverters=true' to your connection string to force
character conversion outside of the `gcj' libraries, or try a different
JDK.

*31.4.5.3.10: ** Updating a table that contains a primary key that is
either `FLOAT' or compound primary key that uses `FLOAT' fails to
update the table and raises an exception.  *

Connector/J adds conditions to the `WHERE' clause during an `UPDATE' to
check the old values of the primary key. If there is no match then
Connector/J considers this a failure condition and raises an exception.

The problem is that rounding differences between supplied values and
the values stored in the database may mean that the values never match,
and hence the update fails. The issue will affect all queries, not just
those from Connector/J.

To prevent this issue, use a primary key that does not use `FLOAT'. If
you have to use a floating point column in your primary key use
`DOUBLE' or `DECIMAL' types in place of `FLOAT'.


File: manual.info,  Node: connector-j-support,  Prev: connector-j-usagenotes,  Up: connector-j

30.4.6 Connector/J Support
--------------------------

* Menu:

* connector-j-support-community::  Connector/J Community Support
* connector-j-support-bug-report::  How to Report Connector/J Bugs or Problems
* connector-j-support-changelog::  Connector/J Change History


File: manual.info,  Node: connector-j-support-community,  Next: connector-j-support-bug-report,  Prev: connector-j-support,  Up: connector-j-support

30.4.6.1 Connector/J Community Support
......................................

MySQL AB provides assistance to the user community by means of its
mailing lists. For Connector/J related issues, you can get help from
experienced users by using the MySQL and Java mailing list. Archives
and subscription information is available online at
`http://lists.mysql.com/java'.

For information about subscribing to MySQL mailing lists or to browse
list archives, visit `http://lists.mysql.com/'. See *Note
mailing-lists::.

Community support from experienced users is also available through the
JDBC Forum (http://forums.mysql.com/list.php?39). You may also find
help from other users in the other MySQL Forums, located at
`http://forums.mysql.com'. See *Note forums::.


File: manual.info,  Node: connector-j-support-bug-report,  Next: connector-j-support-changelog,  Prev: connector-j-support-community,  Up: connector-j-support

30.4.6.2 How to Report Connector/J Bugs or Problems
...................................................

The normal place to report bugs is `http://bugs.mysql.com/', which is
the address for our bugs database. This database is public, and can be
browsed and searched by anyone. If you log in to the system, you will
also be able to enter new reports.

If you have found a sensitive security bug in MySQL, you can send email
to <security@mysql.com>.

Writing a good bug report takes patience, but doing it right the first
time saves time both for us and for yourself. A good bug report,
containing a full test case for the bug, makes it very likely that we
will fix the bug in the next release.

This section will help you write your report correctly so that you
don't waste your time doing things that may not help us much or at all.

If you have a repeatable bug report, please report it to the bugs
database at `http://bugs.mysql.com/'. Any bug that we are able to
repeat has a high chance of being fixed in the next MySQL release.

To report other problems, you can use one of the MySQL mailing lists.

Remember that it is possible for us to respond to a message containing
too much information, but not to one containing too little. People
often omit facts because they think they know the cause of a problem
and assume that some details don't matter.

A good principle is this: If you are in doubt about stating something,
state it. It is faster and less troublesome to write a couple more
lines in your report than to wait longer for the answer if we must ask
you to provide information that was missing from the initial report.

The most common errors made in bug reports are (a) not including the
version number of Connector/J or MySQL used, and (b) not fully
describing the platform on which Connector/J is installed (including
the JVM version, and the platform type and version number that MySQL
itself is installed on).

This is highly relevant information, and in 99 cases out of 100, the
bug report is useless without it. Very often we get questions like,
`Why doesn't this work for me?' Then we find that the feature requested
wasn't implemented in that MySQL version, or that a bug described in a
report has already been fixed in newer MySQL versions.

Sometimes the error is platform-dependent; in such cases, it is next to
impossible for us to fix anything without knowing the operating system
and the version number of the platform.

If at all possible, you should create a repeatable, stanalone testcase
that doesn't involve any third-party classes.

To streamline this process, we ship a base class for testcases with
Connector/J, named 'com.mysql.jdbc.util.BaseBugReport'. To create a
testcase for Connector/J using this class, create your own class that
inherits from com.mysql.jdbc.util.BaseBugReport and override the
methods `setUp()', `tearDown()' and `runTest()'.

In the `setUp()' method, create code that creates your tables, and
populates them with any data needed to demonstrate the bug.

In the `runTest()' method, create code that demonstrates the bug using
the tables and data you created in the `setUp' method.

In the `tearDown()' method, drop any tables you created in the
`setUp()' method.

In any of the above three methods, you should use one of the variants
of the `getConnection()' method to create a JDBC connection to MySQL:

   * `getConnection()' - Provides a connection to the JDBC URL
     specified in `getUrl()'.  If a connection already exists, that
     connection is returned, otherwise a new connection is created.

   * `getNewConnection()' - Use this if you need to get a new
     connection for your bug report (i.e.  there's more than one
     connection involved).

   * `getConnection(String url)' - Returns a connection using the given
     URL.

   * `getConnection(String url, Properties props)' - Returns a
     connection using the given URL and properties.

If you need to use a JDBC URL that is different from
'jdbc:mysql:///test', override the method `getUrl()' as well.

Use the `assertTrue(boolean expression)' and `assertTrue(String
failureMessage, boolean expression)' methods to create conditions that
must be met in your testcase demonstrating the behavior you are
expecting (vs. the behavior you are observing, which is why you are
most likely filing a bug report).

Finally, create a `main()' method that creates a new instance of your
testcase, and calls the `run' method:

     public static void main(String[] args) throws Exception {
           new MyBugReport().run();
      }

Once you have finished your testcase, and have verified that it
demonstrates the bug you are reporting, upload it with your bug report
to `http://bugs.mysql.com/'.


File: manual.info,  Node: connector-j-support-changelog,  Prev: connector-j-support-bug-report,  Up: connector-j-support

30.4.6.3 Connector/J Change History
...................................

The Connector/J Change History (Changelog) is located with the main
Changelog for MySQL. See *Note cj-news::.


File: manual.info,  Node: connector-mxj,  Next: connector-php,  Prev: connector-j,  Up: connectors

30.5 MySQL Connector/MXJ
========================

* Menu:

* connector-mxj-overview::       Connector/MXJ Overview
* connector-mxj-versions::       Connector/MXJ Versions
* connector-mxj-install::        Connector/MXJ Installation
* connector-mxj-configuration::  Connector/MXJ Configuration
* connector-mxj-ref::            Connector/MXJ Reference
* connector-mxj-usagenotes::     Connector/MXJ Notes and Tips
* connector-mxj-support::        Connector/MXJ Support

MySQL Connector/MXJ is a Java Utility package for deploying and
managing a MySQL database. Deploying and using MySQL can be as easy as
adding an additional parameter to the JDBC connection url, which will
result in the database being started when the first connection is made.
This makes it easy for Java developers to deploy applications which
require a database by reducing installation barriers for their
end-users.

MySQL Connector/MXJ makes the MySQL database appear to be a java-based
component. It does this by determining what platform the system is
running on, selecting the appropriate binary, and launching the
executable. It will also optionally deploy an initial database, with
any specified parameters.

Included are instructions for use with a JDBC driver and deploying as a
JMX MBean to JBoss.

You can download sources and binaries from:
`http://dev.mysql.com/downloads/connector/mxj/'

This a beta release and feedback is welcome and encouraged.

Please send questions or comments to the MySQL and Java mailing list
(http://lists.mysql.com/java).


File: manual.info,  Node: connector-mxj-overview,  Next: connector-mxj-versions,  Prev: connector-mxj,  Up: connector-mxj

30.5.1 Connector/MXJ Overview
-----------------------------

Connector/MXJ consists of a Java class, a copy of the `mysqld' binary
for a specific list of platforms, and associated files and support
utilities. The Java class controls the initialization of an instance of
the embedded `mysqld' binary, and the ongoing management of the
`mysqld' process. The entire sequence and management can be controlled
entirely from within Java using the Connector/MXJ Java classes. You can
see an overview of the contents of the Connector/MXJ package in the
figure below.

Connector/MXJ Overview

It is important to note that Connector/MXJ is not an embedded version
of MySQL, or a version of MySQL written as part of a Java class.
Connector/MXJ works through the use of an embedded, compiled binary of
`mysqld' as would normally be used when deploying a standard MySQL
installation.

It is the Connector/MXJ wrapper, support classes and tools, that enable
Connector/MXJ to appear as a MySQL instance.

When Connector/MXJ is initialized, the corresponding `mysqld' binary
for the current platform is extracted, along with a pre-configured data
directed. Both are contained within the Connector/MXJ JAR file. The
`mysqld' instance is then started, with any additional options as
specified during the initialization, and the MySQL database becomes
accessible.

Because Connector/MXJ works in combination with Connector/J, you can
access and integrate with the MySQL instance through a JDBC connection.
When you have finished with the server, the instance is terminated,
and, by default, any data created during the session is retained within
the temporary directory created when the instance was started.

Connector/MXJ and the embedded `mysqld' instance can be deployed in a
number of environments where relying on an existing database, or
installing a MySQL instance would be impossible, including CD-ROM
embedded database applications and temporary database requirements
within a Java-based application environment.


File: manual.info,  Node: connector-mxj-versions,  Next: connector-mxj-install,  Prev: connector-mxj-overview,  Up: connector-mxj

30.5.2 Connector/MXJ Versions
-----------------------------

   * Connector/MXJ 5.x, currently in beta status, includes `mysqld'
     version 5.x and includes binaries for Linux x86, Mac OS X PPC,
     Windows XP/NT/2000 x86 and Solaris SPARC. Connector/MXJ 5.x
     requires the Connector/J 5.x package.

     The exact version of `mysqld' included depends on the version of
     Connector/MXJ

       1. Connector/MXJ v5.0.3 included MySQL v5.0.22

       2. Connector/MXJ v5.0.4 includes MySQL v5.0.27 (Community) or
          MySQL v5.0.32 (Enterprise)

       3. Connector/MXJ v5.0.6 includes MySQL 5.0.37 (Community)

       4. Connector/MXJ v5.0.7 includes MySQL 5.0.41 (Community) or
          MySQL 5.0.42 (Enterprise)

       5. Connector/MXJ v5.0.8 includes MySQL 5.0.45 (Community) or
          MySQL 5.0.46 (Enterprise)

       6. Connector/MXJ v5.0.9 includes MySQL 5.0.51a (Community) or
          MySQL 5.0.54 (Enterprise)

   * Connector/MXJ 1.x includes `mysqld' version 4.1.13 and includes
     binaries for Linux x86, Windows XP/NT/2000 x86 and Solaris SPARC.
     Connector/MXJ 1.x requires the Connector/J 3.x package.

A summary of the different MySQL versions supplied with each
Connector/MXJ release are shown in the table.

Connector/MXJ Version                MySQL Version(s)
5.0.8                                5.0.45 (CS), 5.0.46 (ES)
5.0.7                                5.0.41 (CS), 5.0.42 (ES)
5.0.6                                5.0.37 (CS), 5.0.40 (ES)
5.0.5                                5.0.37 (CS), 5.0.36 (ES)
5.0.4                                5.0.27 (CS), 5.0.32 (ES)
5.0.3                                5.0.22
5.0.2                                5.0.19

This guide provides information on the Connector/MXJ 5.x release.  For
information on using the older releases, please see the documentation
included with the appropriate distribution.


File: manual.info,  Node: connector-mxj-install,  Next: connector-mxj-configuration,  Prev: connector-mxj-versions,  Up: connector-mxj

30.5.3 Connector/MXJ Installation
---------------------------------

* Menu:

* connector-mxj-install-platforms::  Supported Platforms
* connector-mxj-install-base::   Connector/MXJ Base Installation
* connector-mxj-install-quickstart::  Connector/MXJ Quick Start Guide
* connector-mxj-install-class::  Deploying Connector/MXJ using Driver Launch
* connector-mxj-install-jboss::  Deploying Connector/MXJ within JBoss
* connector-mxj-installation-test::  Verifying Installation using JUnit

Connector/MXJ does not have a installation application or process, but
there are some steps you can follow to make the installation and
deployment of Connector/MXJ easier.

Before you start, there are some baseline requirements for

   * Java Runtime Environment (v1.4.0 or newer) if you are only going
     to deploy the package.

   * Java Development Kit (v1.4.0 or newer) if you want to build
     Connector/MXJ from source.

   * Connector/J 5.0 or newer.

Depending on your target installation/deployment environment you may
also require:

   * JBoss - 4.0rc1 or newer

   * Apache Tomcat - 5.0 or newer

   * Sun's JMX reference implementation version 1.2.1 (from
     `http://java.sun.com/products/JavaManagement/')


File: manual.info,  Node: connector-mxj-install-platforms,  Next: connector-mxj-install-base,  Prev: connector-mxj-install,  Up: connector-mxj-install

30.5.3.1 Supported Platforms
............................

Connector/MXJ is compatible with any platform supporting Java and
MySQL. By default, Connector/MXJ incorporates the `mysqld' binary for a
select number of platforms which differs by version. The following
platforms have been tested and working as deployment platforms. Support
for all the platforms listed below is not included by default.

   * Linux (i386)

   * FreeBSD (i386)

   * Windows NT (x86), Windows 2000 (x86), Windows XP (x86), Windows
     Vista (x86)

   * Solaris 8, SPARC 32-bit (compatible with Solaris 8, Solaris 9 and
     Solaris 10 on SPARC 32-bit and 64-bit platforms)

   * Mac OS X (PowerPC and Intel)

The Connector/MXJ 5.0.8 release includes `mysqld' binaries for the
following platforms by as standard:

   * Linux (i386)

   * Windows (x86), compatible with Windows NT, Windows 2000, Windows
     XP , Windows Vista

   * Solaris 8, SPARC 32-bit (compatible with Solaris 8, Solaris 9 and
     Solaris 10 on SPARC 32-bit and 64-bit platforms)

   * Mac OS X (PowerPC and Intel)

For more information on packaging your own Connector/MXJ with the
platforms you require, see *Note connector-mxj-usagenotes-packaging::


File: manual.info,  Node: connector-mxj-install-base,  Next: connector-mxj-install-quickstart,  Prev: connector-mxj-install-platforms,  Up: connector-mxj-install

30.5.3.2 Connector/MXJ Base Installation
........................................

Because there is no formal installation process, the method,
installation directory, and access methods you use for Connector/MXJ
are entirely up to your individual requirements.

To perform a basic installation, choose a target directory for the
files included in the Connector/MXJ package. On Unix/Linux systems you
may opt to use a directory such as `/usr/local/connector-mxj'; On
Windows, you may want to install the files in the base directory,
`C:\Connector-MXJ', or within the `Program Files' directory.

To install the files, for a Connector/MXJ 5.0.4 installation:

  1. Download the Connector/MXJ package, either in Tar/Gzip format
     (ideal for Unix/Linux systems) or Zip format (Windows).

  2. Extract the files from the package. This will create a directory
     `mysql-connector-mxj-gpl-[ver]'. Copy and optionally rename this
     directory to your desired location.

  3. For best results, you should update your global `CLASSPATH'
     variable with the location of the required `jar' files.

     Within Unix/Linux you can do this globally by editing the global
     shell profile, or on a user by user basis by editing their
     individual shell profile.

     On Windows 2000, Windows NT and Windows XP, you can edit the
     global `CLASSPATH' by editing the `Environment Variables'
     configured through the `System' control panel.

For Connector/MXJ 5.0.6 and later you need the following JAR files in
your `CLASSPATH':

  1. `mysql-connector-mxj-gpl-[ver].jar' -- contains the main
     Connector/MXJ classes.

  2. `mysql-connector-mxj-gpl-[ver]-db-files.jar' -- contains the
     embedded `mysqld' and database files.

  3. `aspectjrt.jar' -- the AspectJ runtime library, located in
     `lib/aspectjrt.jar' in the Connector/MXJ package.

  4. `mysql-connector-java-[ver]-bin.jar' -- Connector/J, see *Note
     connector-j::.

For Connector/MXJ 5.0.4 and later you need the following JAR files in
your `CLASSPATH':

  1. `connector-mxj.jar' -- contains the main Connector/MXJ classes.

  2. `connector-mxj-db-files.jar' -- contains the embedded `mysqld' and
     database files.

  3. `aspectjrt.jar' -- the AspectJ runtime library, located in
     `lib/aspectjrt.jar' in the Connector/MXJ package.

  4. `mysql-connector-mxj-gpl-[ver].jar' -- Connector/J, see *Note
     connector-j::.

For Connector/MXJ 5.0.3 and earlier, you need the following JAR files:

  1. `connector-mxj.jar'

  2. `aspectjrt.jar' -- the AspectJ runtime library, located in
     `lib/aspectjrt.jar' in the Connector/MXJ package.

  3. `mysql-connector-mxj-gpl-[ver].jar' -- Connector/J, see *Note
     connector-j::.


File: manual.info,  Node: connector-mxj-install-quickstart,  Next: connector-mxj-install-class,  Prev: connector-mxj-install-base,  Up: connector-mxj-install

30.5.3.3 Connector/MXJ Quick Start Guide
........................................

Once you have extracted the Connector/MXJ and Connector/J components
you can run one of the sample applications that initiates a MySQL
instance. You can test the installation by running the
`ConnectorMXJUrlTestExample':

     $ java ConnectorMXJUrlTestExample
     jdbc:mysql:mxj://localhost:3336/our_test_app?server.basedir»
         =/var/tmp/test-mxj&createDatabaseIfNotExist=true&server.initialize-user=true
     [/var/tmp/test-mxj/bin/mysqld][--no-defaults][--port=3336][--socket=mysql.sock]»
         [--basedir=/var/tmp/test-mxj][--datadir=/var/tmp/test-mxj/data]»
         [--pid-file=/var/tmp/test-mxj/data/MysqldResource.pid]
     [MysqldResource] launching mysqld (driver_launched_mysqld_1)
     InnoDB: The first specified data file ./ibdata1 did not exist:
     InnoDB: a new database to be created!
     080220  9:40:20  InnoDB: Setting file ./ibdata1 size to 10 MB
     InnoDB: Database physically writes the file full: wait...
     080220  9:40:20  InnoDB: Log file ./ib_logfile0 did not exist: new to be created
     InnoDB: Setting log file ./ib_logfile0 size to 5 MB
     InnoDB: Database physically writes the file full: wait...
     080220  9:40:20  InnoDB: Log file ./ib_logfile1 did not exist: new to be created
     InnoDB: Setting log file ./ib_logfile1 size to 5 MB
     InnoDB: Database physically writes the file full: wait...
     InnoDB: Doublewrite buffer not found: creating new
     InnoDB: Doublewrite buffer created
     InnoDB: Creating foreign key constraint system tables
     InnoDB: Foreign key constraint system tables created
     080220  9:40:21  InnoDB: Started; log sequence number 0 0
     080220  9:40:21 [Note] /var/tmp/test-mxj/bin/mysqld: ready for connections.
     Version: '5.0.51a'  socket: 'mysql.sock'  port: 3336  MySQL Community Server (GPL)
     [MysqldResource] mysqld running as process: 2238
     ------------------------
     SELECT VERSION()
     ------------------------
     5.0.51a
     ------------------------
     [MysqldResource] stopping mysqld (process: 2238)
     080220  9:40:27 [Note] /var/tmp/test-mxj/bin/mysqld: Normal shutdown

     080220  9:40:27  InnoDB: Starting shutdown...
     080220  9:40:29  InnoDB: Shutdown completed; log sequence number 0 43655
     080220  9:40:29 [Note] /var/tmp/test-mxj/bin/mysqld: Shutdown complete

     [MysqldResource] shutdown complete

The above output shows an instance of MySQL starting, the necessary
files being created (log files, InnoDB data files) and the MySQL
database entering the running state. The instance is then shutdown by
Connector/MXJ before the example terminates.


File: manual.info,  Node: connector-mxj-install-class,  Next: connector-mxj-install-jboss,  Prev: connector-mxj-install-quickstart,  Up: connector-mxj-install

30.5.3.4 Deploying Connector/MXJ using Driver Launch
....................................................

Connector/MXJ and Connector/J work together to enable you to launch an
instance of the `mysqld' server through the use of a keyword in the
JDBC connection string.  Deploying Connector/MXJ within a Java
application can be automated through this method, making the deployment
of Connector/MXJ a simple process:

  1. Download and unzip Connector/MXJ, add
     `mysql-connector-mxj-gpl-[ver].jar' to the `CLASSPATH'.

     If you are using Connector/MXJ v5.0.4 or later you will also need
     to add the `mysql-connector-mxj-gpl-[ver]-db-files.jar' file to
     your `CLASSPATH'.

  2. To the JDBC connection string, embed the `mxj' keyword, for
     example: `jdbc:mysql:mxj://localhost:PORT/DBNAME'.

For more details, see *Note connector-mxj-configuration::.


File: manual.info,  Node: connector-mxj-install-jboss,  Next: connector-mxj-installation-test,  Prev: connector-mxj-install-class,  Up: connector-mxj-install

30.5.3.5 Deploying Connector/MXJ within JBoss
.............................................

For deployment within a JBoss environment, you must configure the JBoss
environment to use the Connector/MXJ component within the JDBC
parameters:

  1. Download Connector/MXJ and copy the
     `mysql-connector-mxj-gpl-[ver].jar' file to the
     `$JBOSS_HOME/server/default/lib' directory.

     If you are using Connector/MXJ v5.0.4 or later you will also need
     to copy the `mysql-connector-mxj-gpl-[ver]-db-files.jar' file to
     `$JBOSS_HOME/server/default/lib'.

  2. Download Connector/J and copy the
     `mysql-connector-java-5.1.5-bin.jar' file to the
     `$JBOSS_HOME/server/default/lib' directory.

  3. Create an MBean service xml file in the
     `$JBOSS_HOME/server/default/deploy' directory with any attributes
     set, for instance the `datadir' and `autostart'.

  4. Set the JDBC parameters of your web application to use:

          String driver = "com.mysql.jdbc.Driver";
          String url = "jdbc:mysql:///test?propertiesTransform="+
                       "com.mysql.management.jmx.ConnectorMXJPropertiesTransform";
          String user = "root";
          String password = "";
          Class.forName(driver);
          Connection conn = DriverManager.getConnection(url, user, password);

You may wish to create a separate users and database table spaces for
each application, rather than using "root and test".

We highly suggest having a routine backup procedure for backing up the
database files in the `datadir'.


File: manual.info,  Node: connector-mxj-installation-test,  Prev: connector-mxj-install-jboss,  Up: connector-mxj-install

30.5.3.6 Verifying Installation using JUnit
...........................................

* Menu:

* connector-mxj-installation-test-requirements::  JUnit Test Requirements
* connector-mxj-installation-test-running::  Running the JUnit Tests

The best way to ensure that your platform is supported is to run the
JUnit tests. These will test the Connector/MXJ classes and the
associated components.


File: manual.info,  Node: connector-mxj-installation-test-requirements,  Next: connector-mxj-installation-test-running,  Prev: connector-mxj-installation-test,  Up: connector-mxj-installation-test

30.5.3.7 JUnit Test Requirements
................................

The first thing to do is make sure that the components will work on the
platform. The MysqldResource class is really a wrapper for a native
version of MySQL, so not all platforms are supported. At the time of
this writing, Linux on the i386 architecture has been tested and seems
to work quite well, as does OS X v10.3. There has been limited testing
on Windows and Solaris.

Requirements:

  1. JDK-1.4 or newer (or the JRE if you aren't going to be compiling
     the source or JSPs).

  2. MySQL Connector/J version 5.0 or newer (from
     `http://dev.mysql.com/downloads/connector/j/') installed and
     available via your CLASSPATH.

  3. The `javax.management' classes for JMX version 1.2.1, these are
     present in the following application servers:

        * JBoss - 4.0rc1 or newer.

        * Apache Tomcat - 5.0 or newer.

        * Sun's JMX reference implementation version 1.2.1 (from
          `http://java.sun.com/products/JavaManagement/').

  4. JUnit 3.8.1 (from `http://www.junit.org/').

If building from source, All of the requirements from above, plus:

  1. Ant version 1.5 or newer (download from `http://ant.apache.org/').


File: manual.info,  Node: connector-mxj-installation-test-running,  Prev: connector-mxj-installation-test-requirements,  Up: connector-mxj-installation-test

30.5.3.8 Running the JUnit Tests
................................

  1. The tests attempt to launch MySQL on the port 3336. If you have a
     MySQL running, it may conflict, but this isn't very likely because
     the default port for MySQL is 3306.  However, You may set the
     "c-mxj_test_port" Java property to a port of your choosing.
     Alternatively, you may wish to start by shutting down any
     instances of MySQL you have running on the target machine.

     The tests suppress output to the console by default. For verbose
     output, you may set the "c-mxj_test_silent" Java property to
     "false".

  2. To run the JUnit test suite, the $CLASSPATH must include the
     following:

        * JUnit

        * JMX

        * Connector/J

        * MySQL Connector/MXJ

  3. If `connector-mxj.jar' is not present in your download, unzip
     MySQL Connector/MXJ source archive.

          cd mysqldjmx
          ant dist

     Then add `$TEMP/cmxj/stage/connector-mxj/connector-mxj.jar' to the
     CLASSPATH.

  4. if you have `junit', execute the unit tests. From the command
     line, type:

          java com.mysql.management.AllTestsSuite

     The output should look something like this:

          .........................................
          .........................................
          ..........
          Time: 259.438

          OK (101 tests)

     Note that the tests are a bit slow near the end, so please be
     patient.


File: manual.info,  Node: connector-mxj-configuration,  Next: connector-mxj-ref,  Prev: connector-mxj-install,  Up: connector-mxj

30.5.4 Connector/MXJ Configuration
----------------------------------

* Menu:

* connector-mxj-configuration-driver-launched::  Running as part of the JDBC Driver
* connector-mxj-configuration-java-object::  Running within a Java Object
* connector-mxj-configuration-options::  Setting server options


File: manual.info,  Node: connector-mxj-configuration-driver-launched,  Next: connector-mxj-configuration-java-object,  Prev: connector-mxj-configuration,  Up: connector-mxj-configuration

30.5.4.1 Running as part of the JDBC Driver
...........................................

A feature of the MySQL Connector/J JDBC driver is the ability to
specify a connection to an embedded Connector/MXJ instance through the
use of the mxj keyword in the JDBC connection string.

In the following example, we have a program which creates a connection,
executes a query, and prints the result to the System.out. The MySQL
database will be deployed and started as part of the connection
process, and shutdown as part of the finally block.

You can find this file in the Connector/MXJ package as
`src/ConnectorMXJUrlTestExample.java'.

     import java.io.File;
     import java.sql.Connection;
     import java.sql.DriverManager;

     import com.mysql.management.driverlaunched.ServerLauncherSocketFactory;
     import com.mysql.management.util.QueryUtil;

     public class ConnectorMXJUrlTestExample {
       public static String DRIVER = "com.mysql.jdbc.Driver";

       public static String JAVA_IO_TMPDIR = "java.io.tmpdir";

       public static void main(String[] args) throws Exception {
         File ourAppDir = new File(System.getProperty(JAVA_IO_TMPDIR));
         File databaseDir = new File(ourAppDir, "test-mxj");
         int port = Integer.parseInt(System.getProperty("c-mxj_test_port", "3336"));
         String dbName = "our_test_app";

         String url = "jdbc:mysql:mxj://localhost:" + port + "/" + dbName //
           + "?" + "server.basedir=" + databaseDir //
           + "&" + "createDatabaseIfNotExist=true"//
           + "&" + "server.initialize-user=true" //
         ;

         System.out.println(url);

         String userName = "alice";
         String password = "q93uti0opwhkd";

         Class.forName(DRIVER);
         Connection conn = null;
         try {
           conn = DriverManager.getConnection(url, userName, password);
           String sql = "SELECT VERSION()";
           String queryForString = new QueryUtil(conn).queryForString(sql);

           System.out.println("------------------------");
           System.out.println(sql);
           System.out.println("------------------------");
           System.out.println(queryForString);
           System.out.println("------------------------");
           System.out.flush();
           Thread.sleep(100); // wait for System.out to finish flush
         } finally {
           try {
             if (conn != null)
                conn.close();
           } catch (Exception e) {
             e.printStackTrace();
           }

           ServerLauncherSocketFactory.shutdown(databaseDir, null);
         }
       }
     }

To run the above program, be sure to have connector-mxj.jar and
Connector/J in the CLASSPATH. Then type:

     java ConnectorMXJTestExample


File: manual.info,  Node: connector-mxj-configuration-java-object,  Next: connector-mxj-configuration-options,  Prev: connector-mxj-configuration-driver-launched,  Up: connector-mxj-configuration

30.5.4.2 Running within a Java Object
.....................................

If you have a java application and wish to `embed' a MySQL database,
make use of the `com.mysql.management.MysqldResource' class directly.
This class may be instantiated with the default (no argument)
constructor, or by passing in a java.io.File object representing the
directory you wish the server to be "unzipped" into. It may also be
instantiated with printstreams for "stdout" and "stderr" for logging.

Once instantiated, a `java.util.Map', the object will be able to
provide a `java.util.Map' of server options appropriate for the
platform and version of MySQL which you will be using.

The MysqldResource enables you to "start" MySQL with a `java.util.Map'
of server options which you provide, as well as "shutdown" the
database. The following example shows a simplistic way to embed MySQL
in an application using plain java objects.

You can find this file in the Connector/MXJ package as
`src/ConnectorMXJObjectTestExample.java'.

     import java.io.File;
     import java.sql.Connection;
     import java.sql.DriverManager;
     import java.util.HashMap;
     import java.util.Map;

     import com.mysql.management.MysqldResource;
     import com.mysql.management.MysqldResourceI;
     import com.mysql.management.util.QueryUtil;

     public class ConnectorMXJObjectTestExample {
         public static final String DRIVER = "com.mysql.jdbc.Driver";

         public static final String JAVA_IO_TMPDIR = "java.io.tmpdir";

         public static void main(String[] args) throws Exception {
             File ourAppDir = new File(System.getProperty(JAVA_IO_TMPDIR));
             File databaseDir = new File(ourAppDir, "mysql-mxj");
             int port = Integer.parseInt(System.getProperty("c-mxj_test_port",
                     "3336"));
             String userName = "alice";
             String password = "q93uti0opwhkd";

             MysqldResource mysqldResource = startDatabase(databaseDir, port,
                     userName, password);

             Class.forName(DRIVER);
             Connection conn = null;
             try {
                 String dbName = "our_test_app";
                 String url = "jdbc:mysql://localhost:" + port + "/" + dbName //
                         + "?" + "createDatabaseIfNotExist=true"//
                 ;
                 conn = DriverManager.getConnection(url, userName, password);
                 String sql = "SELECT VERSION()";
                 String queryForString = new QueryUtil(conn).queryForString(sql);

                 System.out.println("------------------------");
                 System.out.println(sql);
                 System.out.println("------------------------");
                 System.out.println(queryForString);
                 System.out.println("------------------------");
                 System.out.flush();
                 Thread.sleep(100); // wait for System.out to finish flush
             } finally {
                 try {
                     if (conn != null) {
                         conn.close();
                     }
                 } catch (Exception e) {
                     e.printStackTrace();
                 }
                 try {
                     mysqldResource.shutdown();
                 } catch (Exception e) {
                     e.printStackTrace();
                 }
             }
         }

         public static MysqldResource startDatabase(File databaseDir, int port,
                 String userName, String password) {
             MysqldResource mysqldResource = new MysqldResource(databaseDir);

             Map database_options = new HashMap();
             database_options.put(MysqldResourceI.PORT, Integer.toString(port));
             database_options.put(MysqldResourceI.INITIALIZE_USER, "true");
             database_options.put(MysqldResourceI.INITIALIZE_USER_NAME, userName);
             database_options.put(MysqldResourceI.INITIALIZE_PASSWORD, password);

             mysqldResource.start("test-mysqld-thread", database_options);

             if (!mysqldResource.isRunning()) {
                 throw new RuntimeException("MySQL did not start.");
             }

             System.out.println("MySQL is running.");

             return mysqldResource;
         }
     }


File: manual.info,  Node: connector-mxj-configuration-options,  Prev: connector-mxj-configuration-java-object,  Up: connector-mxj-configuration

30.5.4.3 Setting server options
...............................

Of course there are many options we may wish to set for a MySQL
database. These options may be specified as part of the JDBC connection
string simply by prefixing each server option with `server.'. In the
following example we set two driver parameters and two server
parameters:

             String url = "jdbc:mysql://" + hostColonPort + "/"
                     + "?"
                     + "cacheServerConfiguration=true"
                     + "&"
                     + "useLocalSessionState=true"
                     + "&"
                     + "server.basedir=/opt/myapp/db"
                     + "&"
                     + "server.datadir=/mnt/bigdisk/myapp/data";

Starting with Connector/MXJ 5.0.6 you can use the `initializer-user'
property to a connection string. If set to true, the default anonymous
and root users will be removed and the user/password combination from
the connection URL will be used to create a new user. For example:


             String url = "jdbc:mysql:mxj://localhost:" + port
             + "/alice_db"
             + "?server.datadir=" + dataDir.getPath()
             + "&server.initialize-user=true"
             + "&createDatabaseIfNotExist=true"
             ;


File: manual.info,  Node: connector-mxj-ref,  Next: connector-mxj-usagenotes,  Prev: connector-mxj-configuration,  Up: connector-mxj

30.5.5 Connector/MXJ Reference
------------------------------

* Menu:

* connector-mxj-ref-mysqldresource-ctor::  MysqldResource Constructors
* connector-mxj-ref-mysqldresource-methods::  MysqldResource Methods

The following sections include detailed information on the different
API interfaces to Connector/MXJ.


File: manual.info,  Node: connector-mxj-ref-mysqldresource-ctor,  Next: connector-mxj-ref-mysqldresource-methods,  Prev: connector-mxj-ref,  Up: connector-mxj-ref

30.5.5.1 MysqldResource Constructors
....................................

The `MysqldResource' class supports three different constructor forms:

   * `public MysqldResource(File baseDir, File dataDir, String
     mysqlVersionString, PrintStream out, PrintStream err)'

     Enables you to set the base directory, data directory, select a
     server by its version string, standard out and standard error.

   * `public MysqldResource(File baseDir, File dataDir, String
     mysqlVersionString) '

     Enables you to set the base directory, data directory and select a
     server by its version string. Output for standard out and standard
     err are directed to System.out and System.err.

   * `public MysqldResource(File baseDir, File dataDir) '

     Enables you to set the base directory and data directory.  The
     default MySQL version is selected, and output for standard out and
     standard err are directed to System.out and System.err.

   * `public MysqldResource(File baseDir);'

     Allows the setting of the "basedir" to deploy the MySQL files to.
     Output for standard out and standard err are directed to
     System.out and System.err.

   * `public MysqldResource();'

     The basedir is defaulted to a subdirectory of the java.io.tempdir.
     Output for standard out and standard err are directed to
     System.out and System.err;


File: manual.info,  Node: connector-mxj-ref-mysqldresource-methods,  Prev: connector-mxj-ref-mysqldresource-ctor,  Up: connector-mxj-ref

30.5.5.2 MysqldResource Methods
...............................

MysqldResource API includes the following methods:

   * `void start(String threadName, Map mysqldArgs);'

     Deploys and starts MySQL. The "threadName" string is used to name
     the thread which actually performs the execution of the MySQL
     command line. The map is the set of arguments and their values to
     be passed to the command line.

   * `void shutdown(); '

     Shuts down the MySQL instance managed by the MysqldResource object.

   * ` Map getServerOptions(); '

     Returns a map of all the options and their current (or default, if
     not running) options available for the MySQL database.

   * ` boolean isRunning(); '

     Returns true if the MySQL database is running.

   * ` boolean isReadyForConnections(); '

     Returns true once the database reports that is ready for
     connections.

   * ` void setKillDelay(int millis); '

     The default `Kill Delay' is 30 seconds. This represents the amount
     of time to wait between the initial request to shutdown and
     issuing a `force kill' if the database has not shutdown by itself.

   * ` void addCompletionListenser(Runnable listener); '

     Allows for applications to be notified when the server process
     completes. Each "listener" will be fired off in its own thread.

   * ` String getVersion(); '

     Returns the version of MySQL.

   * ` void setVersion(int MajorVersion, int minorVersion, int
     patchLevel); '

     The standard distribution comes with only one version of MySQL
     packaged. However, it is possible to package multiple versions,
     and specify which version to use.


File: manual.info,  Node: connector-mxj-usagenotes,  Next: connector-mxj-support,  Prev: connector-mxj-ref,  Up: connector-mxj

30.5.6 Connector/MXJ Notes and Tips
-----------------------------------

* Menu:

* connector-mxj-usagenotes-packaging::  Creating your own Connector/MXJ Package
* connector-mxj-usagenotes-customdb::  Deploying Connector/MXJ with a pre-configured database
* connector-mxj-usagenotes-jmx-agent::  Running within a JMX Agent (custom)
* connector-mxj-usagenotes-standard-environment::  Deployment in a standard JMX Agent environment (JBoss)

This section contains notes and tips on using the Connector/MXJ
component within your applications.


File: manual.info,  Node: connector-mxj-usagenotes-packaging,  Next: connector-mxj-usagenotes-customdb,  Prev: connector-mxj-usagenotes,  Up: connector-mxj-usagenotes

30.5.6.1 Creating your own Connector/MXJ Package
................................................

If you want to create a custom Connector/MXJ package that includes a
specific `mysqld' version or platform then you must extract and rebuild
the `mysql-connector-mxj.jar' (Connector/MXJ v5.0.3 or earlier) or
`mysql-connector-mxj-gpl-[ver]-db-files.jar' (Connector/MXJ v5.0.4 or
later) file.

First, you should create a new directory into which you can extract the
current `connector-mxj.jar':

     shell> mkdir custom-mxj
     shell> cd custom-mxj
     shell> jar -xf connector-mxj.jar
     shell> ls
     5-0-22/
     ConnectorMXJObjectTestExample.class
     ConnectorMXJUrlTestExample.class
     META-INF/
     TestDb.class
     com/
     kill.exe

If you are using Connector/MXJ v5.0.4 or later, you should unpack the
`connector-mxj-db-files.jar':

     shell> mkdir custom-mxj
     shell> cd custom-mxj
     shell> jar -xf connector-mxj-db-files.jar
     shell> ls
     5-0-51a/
     META-INF/
     connector-mxj.properties

The MySQL version directory, `5-0-22' or `5-0-51a' in the preceding
examples, contains all of the files used to create an instance of MySQL
when Connector/MXJ is executed. All of the files in this directory are
required for each version of MySQL that you want to embed.  Note as
well the format of the version number, which uses hyphens instead of
periods to separate the version number components.

Within the version specific directory are the platform specific
directories, and archives of the `data' and `share' directory required
by MySQL for the various platforms. For example, here is the listing
for the default Connector/MXJ package:

     shell>> ls
     Linux-i386/
     META-INF/
     Mac_OS_X-ppc/
     SunOS-sparc/
     Win-x86/
     com/
     data_dir.jar
     share_dir.jar
     win_share_dir.jar

Platform specific directories are listed by their OS and platform - for
example the `mysqld' for Mac OS X PowerPC is located within the
`Mac_OS_X-ppc' directory. You can delete directories from this location
that you do not require, and add new directories for additional
platforms that you want to support.

To add a platform specific `mysqld', create a new directory with the
corresponding name for your operating system/platform. For example, you
could add a directory for Mac OS X/Intel using the directory
`Mac_OS_X-i386'.

On Unix systems, you can determine the platform using `uname':

     shell> uname -p
     i386

In Connector/MXJ v5.0.9 and later, an additional
`platform-map.properties' file is used to associate a specific platform
and operating system combination with the directory in which the
`mysqld' for that combination is located. The determined operating
system and platform are on the left, and the directory name where the
appropriate mysqld is located is on the right. You can see a sample of
the file below:

     Linux-i386=Linux-i386
     Linux-x86=Linux-i386
     Linux-i686=Linux-i386
     Linux-x86_64=Linux-i386
     Linux-ia64=Linux-i386

     #Linux-ppc=Linux-ppc
     #Linux-ppc64=Linux-ppc

     Mac_OS_X-i386=Mac_OS_X-i386
     Mac_OS_X-ppc=Mac_OS_X-ppc
     Rhapsody-PowerPC=Mac_OS_X-ppc
     #Mac_OS-PowerPC=
     #macos-PowerPC=
     #MacOS-PowerPC=

     SunOS-sparc=SunOS-sparc
     Solaris-sparc=SunOS-sparc
     SunOS-x86=SunOS-x86
     Solaris-x86=SunOS-x86

     FreeBSD-x86=FreeBSD-x86

     Windows_Vista-x86=Win-x86
     Windows_2003-x86=Win-x86
     Windows_XP-x86=Win-x86
     Windows_2000-x86=Win-x86
     Windows_NT-x86=Win-x86
     Windows_NT_(unknown)-x86=Win-x86

Now you need to download or compile `mysqld' for the MySQL version and
platform you want to include in your custom `connector-mxj.jar' package
into the new directory.

Create a file called `version.txt' in the OS/platform directory you
have just created that contains the version string/path of the mysqld
binary. For example:

     mysql-5.0.22-osx10.3-i386/bin/mysqld

You can now recreate the `connector-mxj.jar' file with the added
`mysqld':

     shell> cd custom-mxj
     shell> jar -cf ../connector-mxj.jar *

For Connector/MXJ v5.0.4 and later, you should repackage to the
`connector-mxj-db-files.jar':

     shell> cd custom-mxj
     shell> jar -cf ../mysql-connector-mxj-gpl-[ver]-db-files.jar *

You should test this package using the steps outlined in *Note
connector-mxj-install-quickstart::.

*Note*:

Because the `mysql-connector-mxj-gpl-[ver]-db-files.jar' file is
separate from the main Connector/MXJ classes you can distribute
different `mysql-connector-mxj-gpl-[ver]-db-files.jar' files to
different hotsts or for different projects without having to create a
completely new main `mysql-connector-mxj-gpl-[ver].jar' file for each
one.


File: manual.info,  Node: connector-mxj-usagenotes-customdb,  Next: connector-mxj-usagenotes-jmx-agent,  Prev: connector-mxj-usagenotes-packaging,  Up: connector-mxj-usagenotes

30.5.6.2 Deploying Connector/MXJ with a pre-configured database
...............................................................

To include a pre-configured/populated database within your
Connector/MXJ JAR file you must create a custom `data_dir.jar' file, as
included within the main `connector-mxj.jar' (Connector/MXJ 5.0.3 or
earlier) or `mysql-connector-mxj-gpl-[ver]-db-files.jar' (Connector/MXJ
5.0.4 or later) file:

  1. First extract the `connector-mxj.jar' or
     `mysql-connector-gpl-[ver]-db-files.jar' file, as outlined in the
     previous section (see *Note connector-mxj-usagenotes-packaging::).

  2. First, create your database and populate the database with the
     information you require in an existing instance of MySQL -
     including Connector/MXJ instances. Data file formats are
     compatible across platforms.

  3. Shutdown the instance of MySQL.

  4. Create a JAR file of the data directory and databases that you
     want to include your Connector/MXJ package. You should include the
     `mysql' database, which includes user authentication information,
     in addition to the specific databases you want to include. For
     example, to create a JAR of the `mysql' and `mxjtest' databases:

          shell> jar -cf ../data_dir.jar mysql mxjtest

  5. For Connector/MXJ 5.0.3 or earlier, copy the `data_dir.jar' file
     into the extracted `connector-mxj.jar' directory, and then create
     an archive for `connector-mxj.jar'.

     For Connector/MXJ 5.0.4 or later, copy the `data_dir.jar' file
     into the extracted `mysql-connector-mxj-gpl-[ver]-db-files.jar'
     directory, and then create an archive for
     `mysql-connector-mxj-db-gpl-[ver]--files.jar'.

Note that if you are create databases using the InnoDB engine, you must
include the `ibdata.*' and `ib_logfile*' files within the
`data_dir.jar' archive.


File: manual.info,  Node: connector-mxj-usagenotes-jmx-agent,  Next: connector-mxj-usagenotes-standard-environment,  Prev: connector-mxj-usagenotes-customdb,  Up: connector-mxj-usagenotes

30.5.6.3 Running within a JMX Agent (custom)
............................................

As a JMX MBean, MySQL Connector/MXJ requires a JMX v1.2 compliant MBean
container, such as JBoss version 4. The MBean will uses the standard
JMX management APIs to present (and allow the setting of) parameters
which are appropriate for that platform.

If you are not using the SUN Reference implementation of the JMX
libraries, you should skip this section. Or, if you are deploying to
JBoss, you also may wish to skip to the next section.

We want to see the MysqldDynamicMBean in action inside of a JMX agent.
In the `com.mysql.management.jmx.sunri' package is a custom JMX agent
with two MBeans:

  1. the MysqldDynamicMBean, and

  2. a com.sun.jdmk.comm.HtmlAdaptorServer, which provides a web
     interface for manipulating the beans inside of a JMX agent.

When this very simple agent is started, it will allow a MySQL database
to be started and stopped with a web browser.

  1. Complete the testing of the platform as above.

        * current JDK, JUnit, Connector/J, MySQL Connector/MXJ

        * this section _requires_ the SUN reference implementation of
          JMX

        * `PATH', `JAVA_HOME', `ANT_HOME', `CLASSPATH'

  2. If not building from source, skip to next step

     rebuild with the "sunri.present"

          ant -Dsunri.present=true dist
          re-run tests:
          java junit.textui.TestRunner com.mysql.management.AllTestsSuite

  3. launch the test agent from the command line:

          java com.mysql.management.jmx.sunri.MysqldTestAgentSunHtmlAdaptor &

  4. from a browser:

          http://localhost:9092/

  5. under MysqldAgent,

          select "name=mysqld"

  6. Observe the MBean View

  7. scroll to the bottom of the screen press the `startMysqld' button

  8. click `Back to MBean View'

  9. scroll to the bottom of the screen press `stopMysqld' button

 10. kill the java process running the Test Agent (jmx server)


File: manual.info,  Node: connector-mxj-usagenotes-standard-environment,  Prev: connector-mxj-usagenotes-jmx-agent,  Up: connector-mxj-usagenotes

30.5.6.4 Deployment in a standard JMX Agent environment (JBoss)
...............................................................

Once there is confidence that the MBean will function on the platform,
deploying the MBean inside of a standard JMX Agent is the next step.
Included are instructions for deploying to JBoss.

  1. Ensure a current version of java development kit (v1.4.x), see
     above.

        * Ensure `JAVA_HOME' is set (JBoss requires `JAVA_HOME')

        * Ensure `JAVA_HOME/bin' is in the `PATH' (You will NOT need to
          set your CLASSPATH, nor will you need any of the jars used in
          the previous tests).

  2. Ensure a current version of JBoss (v4.0RC1 or better)

          http://www.jboss.org/index.html
          select "Downloads"
          select "jboss-4.0.zip"
          pick a mirror
          unzip ~/dload/jboss-4.0.zip
          create a JBOSS_HOME environment variable set to the unzipped directory
          unix only:
          cd $JBOSS_HOME/bin
          chmod +x *.sh

  3. Deploy (copy) the `connector-mxj.jar' to
     `$JBOSS_HOME/server/default/lib'.

  4. Deploy (copy) `mysql-connector-java-3.1.4-beta-bin.jar' to
     `$JBOSS_HOME/server/default/lib'.

  5. Create a `mxjtest.war' directory in
     `$JBOSS_HOME/server/default/deploy'.

  6. Deploy (copy) `index.jsp' to
     `$JBOSS_HOME/server/default/deploy/mxjtest.war'.

  7. Create a `mysqld-service.xml' file in
     `$JBOSS_HOME/server/default/deploy'.

          <?xml version="1.0" encoding="UTF-8"?>
           <server>
            <mbean code="com.mysql.management.jmx.jboss.JBossMysqldDynamicMBean"
               name="mysql:type=service,name=mysqld">
            <attribute name="datadir">/tmp/xxx_data_xxx</attribute>
            <attribute name="autostart">true</attribute>
            </mbean>
           </server>

  8. Start jboss:

        * on unix: `$JBOSS_HOME/bin/run.sh'

        * on windows: `%JBOSS_HOME%\bin\run.bat'

     Be ready: JBoss sends a lot of output to the screen.

  9. When JBoss seems to have stopped sending output to the screen,
     open a web browser to: `http://localhost:8080/jmx-console'

 10. Scroll down to the bottom of the page in the `mysql' section,
     select the bulleted `mysqld' link.

 11. Observe the JMX MBean View page. MySQL should already be running.

 12. (If "autostart=true" was set, you may skip this step.)  Scroll to
     the bottom of the screen. You may press the `Invoke' button to
     stop (or start) MySQL observe `Operation completed successfully
     without a return value.' Click `Back to MBean View'

 13. To confirm MySQL is running, open a web browser to
     `http://localhost:8080/mxjtest/' and you should see that

          SELECT 1

     returned with a result of

          1

 14. Guided by the
     `$JBOSS_HOME/server/default/deploy/mxjtest.war/index.jsp' you will
     be able to use MySQL in your Web Application. There is a `test'
     database and a `root' user (no password) ready to experiment with.
     Try creating a table, inserting some rows, and doing some selects.

 15. Shut down MySQL. MySQL will be stopped automatically when JBoss is
     stopped, or: from the browser, scroll down to the bottom of the
     MBean View press the stop service `Invoke' button to halt the
     service.  Observe `Operation completed successfully without a
     return value.' Using `ps' or `task manager' see that MySQL is no
     longer running

As of 1.0.6-beta version is the ability to have the MBean start the
MySQL database upon start up. Also, we've taken advantage of the JBoss
life-cycle extension methods so that the database will gracefully shut
down when JBoss is shutdown.


File: manual.info,  Node: connector-mxj-support,  Prev: connector-mxj-usagenotes,  Up: connector-mxj

30.5.7 Connector/MXJ Support
----------------------------

* Menu:

* connector-mxj-support-community::  Connector/MXJ Community Support
* connector-mxj-support-bug-report::  How to Report Connector/MXJ Problems
* connector-mxj-support-changelog::  Connector/MXJ Change History

There are a wide variety of options available for obtaining support for
using Connector/MXJ. You should contact the Connector/MXJ community for
help before reporting a potential bug or problem. See *Note
connector-mxj-support-community::.


File: manual.info,  Node: connector-mxj-support-community,  Next: connector-mxj-support-bug-report,  Prev: connector-mxj-support,  Up: connector-mxj-support

30.5.7.1 Connector/MXJ Community Support
........................................

MySQL AB provides assistance to the user community by means of a number
of mailing lists and web based forums.

You can find help and support through the MySQL and Java
(http://lists.mysql.com/java) mailing list.

For information about subscribing to MySQL mailing lists or to browse
list archives, visit `http://lists.mysql.com/'. See *Note
mailing-lists::.

Community support from experienced users is also available through the
MyODBC Forum (http://forums.mysql.com/list.php?39). You may also find
help from other users in the other MySQL Forums, located at
`http://forums.mysql.com'. See *Note forums::.


File: manual.info,  Node: connector-mxj-support-bug-report,  Next: connector-mxj-support-changelog,  Prev: connector-mxj-support-community,  Up: connector-mxj-support

30.5.7.2 How to Report Connector/MXJ Problems
.............................................

If you encounter difficulties or problems with Connector/MXJ, contact
the Connector/MXJ community *Note connector-mxj-support-community::.

If reporting a problem, you should ideally include the following
information with the email:

   * Operating system and version

   * Connector/MXJ version

   * MySQL server version

   * Copies of error messages or other unexpected output

   * Simple reproducible sample

Remember that the more information you can supply to us, the more
likely it is that we can fix the problem.

If you believe the problem to be a bug, then you must report the bug
through `http://bugs.mysql.com/'.


File: manual.info,  Node: connector-mxj-support-changelog,  Prev: connector-mxj-support-bug-report,  Up: connector-mxj-support

30.5.7.3 Connector/MXJ Change History
.....................................

The Connector/MXJ Change History (Changelog) is located with the main
Changelog for MySQL. See *Note news-connector-mxj::.


File: manual.info,  Node: connector-php,  Prev: connector-mxj,  Up: connectors

30.6 Connector/PHP
==================

The PHP distribution and documentation are available from the PHP Web
site. MySQL provides the `mysql' and `mysqli' extensions for the
Windows operating system on
`http://dev.mysql.com/downloads/connector/php/' for MySQL version
4.1.16 and higher, MySQL 5.0.18, and MySQL 5.1. You can find
information why you should preferably use the extensions provided by
MySQL on that page. For platforms other than Windows, you should use
the `mysql' or `mysqli' extensions shipped with the PHP sources.  See
*Note php::.


File: manual.info,  Node: extending-mysql,  Next: faqs,  Prev: connectors,  Up: Top

31 Extending MySQL
******************

* Menu:

* mysql-internals::              MySQL Internals
* plugin-api::                   The MySQL Plugin Interface
* adding-functions::             Adding New Functions to MySQL
* adding-procedures::            Adding New Procedures to MySQL
* porting::                      Debugging and Porting MySQL


File: manual.info,  Node: mysql-internals,  Next: plugin-api,  Prev: extending-mysql,  Up: extending-mysql

31.1 MySQL Internals
====================

* Menu:

* mysql-threads::                MySQL Threads
* mysql-test-suite::             MySQL Test Suite

This chapter describes a lot of things that you need to know when
working on the MySQL code. If you plan to contribute to MySQL
development, want to have access to the bleeding-edge versions of the
code, or just want to keep track of development, follow the
instructions in *Note installing-source-tree::. If you are interested
in MySQL internals, you should also subscribe to our `internals'
mailing list. This list has relatively low traffic. For details on how
to subscribe, please see *Note mailing-lists::. All developers at MySQL
AB are on the `internals' list and we help other people who are working
on the MySQL code. Feel free to use this list both to ask questions
about the code and to send patches that you would like to contribute to
the MySQL project!


File: manual.info,  Node: mysql-threads,  Next: mysql-test-suite,  Prev: mysql-internals,  Up: mysql-internals

31.1.1 MySQL Threads
--------------------

The MySQL server creates the following threads:

   * Connection manager threads handle client connection requests on
     the network interfaces that the server listens to. On all
     platforms, one manager thread handles TCP/IP connection requests.
     On Unix, this manager thread also handles Unix socket file
     connection requests. On Windows, a manager thread handles
     shared-memory connection requests, and another handles named-pipe
     connection requests. The server does not create threads to handle
     interfaces that it does not listen to. For example, a Windows
     server that does not have support for named-pipe connections
     enabled does not create a thread to handle them.

   * Connection manager threads associate each client connection with a
     thread dedicated to it that handles authentication and request
     processing for that connection. Manager threads create a new
     thread when necessary but try to avoid doing so by consulting the
     thread cache first to see whether it contains a thread that can be
     used for the connection. When a connection ends, its thread is
     returned to the thread cache if the cache is not full.

     For information about tuning the parameters that control thread
     resources, see *Note connection-threads::.

   * On a master replication server, connections from slave servers are
     handled like client connections: There is one thread per connected
     slave.

   * On a slave replication server, an I/O thread is started to connect
     to the master server and read updates from it. An SQL thread is
     started to apply updates read from the master.  These two threads
     run independently and can be started and stopped independently.

   * A signal thread handles all signals. This thread also normally
     handles alarms and calls `process_alarm()' to force timeouts on
     connections that have been idle too long.

   * If `InnoDB' is used, there will be 4 additional threads by
     default. Those are file I/O threads, controlled by the
     `innodb_file_io_threads' parameter. See *Note innodb-parameters::.

   * If `mysqld' is compiled with `-DUSE_ALARM_THREAD', a dedicated
     thread that handles alarms is created. This is only used on some
     systems where there are problems with `sigwait()' or if you want
     to use the `thr_alarm()' code in your application without a
     dedicated signal handling thread.

   * If the server is started with the `--flush_time=VAL' option, a
     dedicated thread is created to flush all tables every VAL seconds.

   * Each table for which `INSERT DELAYED' statements are issued gets
     its own thread. See *Note insert-delayed::.

   * If the event scheduler is active, there is one thread for the
     scheduler, and a thread for each event currently running. See
     *Note events-overview::.

`mysqladmin processlist' only shows the connection, `INSERT DELAYED',
replication, and event threads.

MySQL Enterprise

For expert advice on thread management subscribe to the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: mysql-test-suite,  Prev: mysql-threads,  Up: mysql-internals

31.1.2 MySQL Test Suite
-----------------------

The test system that is included in Unix source and binary
distributions makes it possible for users and developers to perform
regression tests on the MySQL code. These tests can be run on Unix.

The current set of test cases doesn't test everything in MySQL, but it
should catch most obvious bugs in the SQL processing code, operating
system or library issues, and is quite thorough in testing replication.
Our goal is to have the tests cover 100% of the code. We welcome
contributions to our test suite. You may especially want to contribute
tests that examine the functionality critical to your system because
this ensures that all future MySQL releases work well with your
applications.

The test system consists of a test language interpreter (`mysqltest'),
a Perl script to run all tests (`mysql-test-run.pl'), the actual test
cases written in a special test language, and their expected results.
To run the test suite on your system after a build, type `make test'
from the source root directory, or change location to the `mysql-test'
directory and type `./mysql-test-run.pl'. If you have installed a
binary distribution, change location to the `mysql-test' directory
under the installation root directory (for example,
`/usr/local/mysql/mysql-test'), and run `./mysql-test-run.pl'. All
tests should succeed. If any do not, feel free to try to find out why
and report the problem if it indicates a bug in MySQL. See *Note
bug-reports::.

If one test fails, you should run `mysql-test-run.pl' with the
`--force' option to check whether any other tests fail.

If you have a copy of `mysqld' running on the machine where you want to
run the test suite, you do not have to stop it, as long as it is not
using ports `9306' or `9307'. If either of those ports is taken, you
should set the `MTR_BUILD_THREAD' environment variable to an
appropriate value, and the test suite will use a different set of ports
for master, slave, NDB, and Instance Manager). For example:

     shell> export MTR_BUILD_THREAD=31
     shell> ./mysql-test-run.pl [OPTIONS] [TEST_NAME]

In the `mysql-test' directory, you can run an individual test case with
`./mysql-test-run.pl TEST_NAME'.

You can use the `mysqltest' language to write your own test cases. This
is documented in the MySQL Test Framework manual, available at
`http://dev.mysql.com/doc/'.

If you have a question about the test suite, or have a test case to
contribute, send an email message to the MySQL `internals' mailing
list. See *Note mailing-lists::. This list does not accept attachments,
so you should FTP all the relevant files to:
`ftp://ftp.mysql.com/pub/mysql/upload/'


File: manual.info,  Node: plugin-api,  Next: adding-functions,  Prev: mysql-internals,  Up: extending-mysql

31.2 The MySQL Plugin Interface
===============================

* Menu:

* plugin-api-characteristics::   Characteristics of the Plugin Interface
* plugin-full-text-plugins::     Full-Text Parser Plugins
* plugin-writing::               Writing Plugins

MySQL 5.1 and up supports a plugin API that allows the loading and
unloading of server components at runtime, without restarting the
server. The components supported by this operation include, but are not
limited to, full-text parser plugins, storage-engines and server
extensions. In MySQL 5.1 the storage engines can be included in the
server as oplugins.

Full-text parser plugins can be used to replace or augment the built-in
full-text parser. For example, a plugin can parse text into words using
rules that differ from those used by the built-in parser. This can be
useful if you need to parse text with characteristics different from
those expected by the built-in parser.

The plugin interface is intended as the successor to the older
user-defined function (UDF) interface. The plugin interface eventually
will include an API for creating UDFs, and it is intended this plugin
UDF API will replace the older non-plugin UDF API. After that point, it
will be possible for UDFs to be revised for use as plugin UDFs so that
they can take advantage of the better security and versioning
capabilities of the plugin API.  Eventually, support for the older UDF
API will be phased out.

The plugin interface requires the `plugin' table in the `mysql'
database. This table is created as part of the MySQL installation
process. If you are upgrading from an older version to MySQL 5.1, you
should run the `mysql_upgrade' command to create this table. See *Note
mysql-upgrade::.

For more information on the Plugin API and how it can be used with
storage engines, see MySQL Internals: Custom Engine
(http://forge.mysql.com/wiki/MySQL_Internals_Custom_Engine).


File: manual.info,  Node: plugin-api-characteristics,  Next: plugin-full-text-plugins,  Prev: plugin-api,  Up: plugin-api

31.2.1 Characteristics of the Plugin Interface
----------------------------------------------

In some respects, the plugin API is similar to the older user-defined
function (UDF) API that it supersedes, but the plugin API has several
advantages over the older interface:

   * The plugin framework is extendable to accommodate different kinds
     of plugins.

     Some aspects of the plugin API are common to all types of plugins,
     but the API also allows for type-specific interface elements so
     that different types of plugins can be created.  A plugin with one
     purpose can have an interface most appropriate to its own
     requirements and not the requirements of some other plugin type.

     Although only the interface for full-text parser plugins is
     implemented currently, others can be added, such as an interface
     for UDF plugins.

   * The plugin API includes versioning information.

     The version information included in the plugin API enables a
     plugin library and each plugin that it contains to be
     self-identifying with respect to the API version that was used to
     build the library. If the API changes over time, the version
     numbers will change, but a server can examine a given plugin
     library's version information to determine whether it supports the
     plugins in the library.

     There are two types of version numbers. The first is the version
     for the general plugin framework itself. Each plugin library
     includes this kind of version number. The second type of version
     applies to individual plugins. Each specific type of plugin has a
     version for its interface, so each plugin in a library has a
     type-specific version number. For example, library containing a
     full-text parsing plugin has a general plugin API version number,
     and the plugin has a version number specific to the full-text
     plugin interface.

   * Plugin security is improved relative to the UDF interface.

     The older interface for writing non-plugin UDFs allowed libraries
     to be loaded from any directory searched by the system's dynamic
     linker, and the symbols that identified the UDF library were
     relatively non-specific. The newer rules are more strict. A plugin
     library must be installed in a specific dedicated directory for
     which the location is controlled by the server and cannot be
     changed at runtime.  Also, the library must contain specific
     symbols that identify it as a plugin library. The server will not
     load something as a plugin if it was not built as a plugin.

     The newer plugin interface eliminates the security issues of the
     older UDF interface. When a UDF plugin type is implemented, that
     will allow non-plugin UDFs to be brought into the plugin framework
     and the older interface to be phased out.

The plugin implementation includes the following components:

Source files (the locations given indicate where the files are found in
a MySQL source distribution):

   * `include/mysql/plugin.h' exposes the public plugin API. This file
     should be examined by anyone who wants to write a plugin library.

   * `sql/sql_plugin.h' and `sql/sql_plugin.cc' comprise the internal
     plugin implementation. These files need not be consulted by plugin
     writers. They may be of interest for those who want to know more
     about how the server handles plugins.

System table:

   * The `plugin' table in the `mysql' database lists each installed
     plugin and is required for plugin use. For new MySQL
     installations, this table is created during the installation
     process. If you are upgrading from a version older than MySQL 5.1,
     you should run `mysql_upgrade' to update your system tables and
     create the `plugin' table (see *Note mysql-upgrade::).

SQL statements:

   * `INSTALL PLUGIN' registers a plugin in the `plugin' table and
     loads the plugin code.

   * `UNINSTALL PLUGIN' unregisters a plugin from the `plugin' table
     and unloads the plugin code.

   * The `WITH PARSER' clause for full-text index creation associates a
     full-text parser plugin with a given `FULLTEXT' index.

   * `SHOW PLUGINS' displays information about known plugins. The
     `PLUGINS' table in `INFORMATION_SCHEMA' also contains plugin
     information.

System variable:

   * `plugin_dir' indicates the location of the directory where all
     plugins must be installed. The value of this variable can be
     specified at server startup with a `--plugin_dir=PATH' option. As
     of MySQL 6.0.5, `mysql_config --plugindir' displays the default
     plugin directory pathname.


File: manual.info,  Node: plugin-full-text-plugins,  Next: plugin-writing,  Prev: plugin-api-characteristics,  Up: plugin-api

31.2.2 Full-Text Parser Plugins
-------------------------------

MySQL has a built-in parser that it uses by default for full-text
operations (parsing text to be indexed, or parsing a query string to
determine the terms to be used for a search).  For full-text
processing, `parsing' means extracting words from text or a query
string based on rules that define which character sequences make up a
word and where word boundaries lie.

When parsing for indexing purposes, the parser passes each word to the
server, which adds it to a full-text index. When parsing a query
string, the parser passes each word to the server, which accumulates
the words for use in a search.

The parsing properties of the built-in full-text parser are described
in *Note fulltext-search::. These properties include rules for
determining how to extract words from text.  The parser is influenced
by certain system variables such as `ft_min_word_len' and
`ft_max_word_len' that cause words shorter or longer to be excluded,
and by the stopword list that identifies common words to be ignored.

The plugin API enables you to provide a full-text parser of your own so
that you have control over the basic duties of a parser.  A parser
plugin can operate in either of two roles:

   * The plugin can replace the built-in parser. In this role, the
     plugin reads the input to be parsed, splits it up into words, and
     passes the words to the server (either for indexing or for word
     accumulation).

     One reason to use a parser this way is that you need to use
     different rules from those of the built-in parser for determining
     how to split up input into words. For example, the built-in parser
     considers the text `case-sensitive' to consist of two words `case'
     and `sensitive,' whereas an application might need to treat the
     text as a single word.

   * The plugin can act in conjunction with the built-in parser by
     serving as a front end for it. In this role, the plugin extracts
     text from the input and passes the text to the parser, which
     splits up the text into words using its normal parsing rules. In
     particular, this parsing will be affected by the `ft_XXX' system
     variables and the stopword list.

     One reason to use a parser this way is that you need to index
     content such as PDF documents, XML documents, or `.doc' files. The
     built-in parser is not intended for those types of input but a
     plugin can pull out the text from these input sources and pass it
     to the built-in parser.

It is also possible for a parser plugin to operate in both roles. That
is, it could extract text from non-plaintext input (the front end
role), and also parse the text into words (thus replacing the built-in
parser).

A full-text plugin is associated with full-text indexes on a per-index
basis. That is, when you install a parser plugin initially, that does
not cause it to be used for any full-text operations. It simply becomes
available. For example, a full-text parser plugin becomes available to
be named in a `WITH PARSER' clause when creating individual `FULLTEXT'
indexes. To create such an index at table-creation time, do this:

     CREATE TABLE t
     (
       doc CHAR(255),
       FULLTEXT INDEX (doc) WITH PARSER my_parser
     );

Or you can add the index after the table has been created:

     ALTER TABLE t ADD FULLTEXT INDEX (doc) WITH PARSER my_parser;

The only SQL change for associating the parser with the index is the
`WITH PARSER' clause. Searches are specified as before, with no changes
needed for queries.

When you associate a parser plugin with a `FULLTEXT' index, the plugin
is required for using the index. If the parser plugin is dropped, any
index associated with it becomes unusable. Any attempt to use it a
table for which a plugin is not available results in an error, although
`DROP TABLE' is still possible.


File: manual.info,  Node: plugin-writing,  Prev: plugin-full-text-plugins,  Up: plugin-api

31.2.3 Writing Plugins
----------------------

* Menu:

* plugin-api-general::           General Plugin Structures and Functions
* plugin-api-type-specific::     Type-Specific Plugin Structures and Functions
* plugin-creating::              Creating a Plugin Library

This section describes the general and type-specific parts of the
plugin API. It also provides a step-by-step guide to creating a plugin
library. For example plugin source code, see the `plugin/fulltext'
directory of a MySQL source distribution.

You can write plugins in C or C++ (or another language that can use C
calling conventions). Plugins are loaded and unloaded dynamically, so
your operating system must support dynamic loading and you must have
compiled `mysqld' dynamically (not statically).

A plugin contains code that becomes part of the running server, so when
you write a plugin, you are bound by any and all constraints that
otherwise apply to writing server code. For example, you may have
problems if you attempt to use functions from the `libstdc++' library.
These constraints may change in future versions of the server, so it is
possible that server upgrades will require revisions to plugins that
were originally written for older servers. For information about these
constraints, see *Note configure-options::, and *Note
compilation-problems::.


File: manual.info,  Node: plugin-api-general,  Next: plugin-api-type-specific,  Prev: plugin-writing,  Up: plugin-writing

31.2.3.1 General Plugin Structures and Functions
................................................

Every plugin must have a general plugin declaration. The declaration
corresponds to the `st_mysql_plugin' structure in the `plugin.h' file:

     struct st_mysql_plugin
     {
       int type;             /* the plugin type (a MYSQL_XXX_PLUGIN value)   */
       void *info;           /* pointer to type-specific plugin descriptor   */
       const char *name;     /* plugin name                                  */
       const char *author;   /* plugin author (for SHOW PLUGINS)             */
       const char *descr;    /* general descriptive text (for SHOW PLUGINS ) */
       int license;          /* the plugin license (PLUGIN_LICENSE_XXX)      */
       int (*init)(void *);  /* the function to invoke when plugin is loaded */
       int (*deinit)(void *);/* the function to invoke when plugin is unloaded */
       unsigned int version; /* plugin version (for SHOW PLUGINS)            */
       struct st_mysql_show_var *status_vars;
       void * __reserved1;   /* placeholder for system variables             */
       void * __reserved2;   /* placeholder for config options               */
     };

The `st_mysql_plugin' structure is common to every type of plugin. Its
members should be filled in as follows:

   * `type'

     The plugin type. This must be one of the plugin-type values from
     `plugin.h'. For a full-text parser plugin, the `type' value is
     `MYSQL_FTPARSER_PLUGIN'.

   * `info'

     A pointer to the descriptor for the plugin. Unlike the general
     plugin declaration structure, this descriptor's structure depends
     on the particular type of plugin. Each descriptor has a version
     number that indicates the API version for that type of plugin,
     plus any other members needed. The descriptor for full-text
     plugins is described in *Note plugin-api-type-specific::.

   * `name'

     The plugin name. This is the name that will be listed in the
     `plugin' table and by which you refer to the plugin in SQL
     statements such as `INSTALL PLUGIN' and `UNINSTALL PLUGIN'.

   * `author'

     The plugin author. This can be whatever you like.

   * `desc'

     A general description of the plugin. This can be whatever you like.

   * `license'

     The plugin license type. The value can be one of
     `PLUGIN_LICENSE_PROPRIETARY', `PLUGIN_LICENSE_GPL', or
     `PLUGIN_LICENSE_BSD'.

   * `init'

     A once-only initialization function. This is executed when the
     plugin is loaded, which happens for `INSTALL PLUGIN' or, for
     plugins listed in the `plugin' table, at server startup. The
     function takes no arguments. It returns zero for success and
     non-zero for failure. If an `init' function is unneeded for a
     plugin, it can be specified as 0.

   * `deinit'

     A once-only deinitialization function. This is executed when the
     plugin is unloaded, which happens for `UNINSTALL PLUGIN' or, for
     plugins listed in the `plugin' table, at server shutdown. The
     function takes no arguments. It returns zero for success and
     non-zero for failure. If a `deinit' function is unneeded for a
     plugin, it can be specified as 0.

   * `version'

     The plugin version number. When the plugin is installed, this
     value can be retrieved from the `INFORMATION_SCHEMA.PLUGINS'
     table. The value includes major and minor numbers. If you write the
     value as a hex constant, the format is `0xMMNN', where MM and `NN'
     are the major and minor numbers, respectively. For example,
     `0x0302' represents version 3.2.

   * `status_vars'

     A pointer to a structure for status variables associated with the
     plugin, or 0 if there are no such variables. When the plugin is
     installed, these variables are displayed in the output of the
     `SHOW STATUS' statement.

   * `__reserved1', `__reserved2'

     These are placeholders for the future. Currently, they should be
     set to `NULL'.

The `init' and `deinit' functions in the general plugin declaration are
invoked only when loading and unloading the plugin. They have nothing
to do with use of the plugin such as happens when an SQL statement
causes the plugin to be invoked.

The `status_vars' member, if not 0, points to an array of
`st_mysql_show_var' structures, each of which describes one status
variable, followed by a structure with all members set to 0. The
`st_mysql_show_var' structure has this definition:

     struct st_mysql_show_var {
       const char *name;
       char *value;
       enum enum_mysql_show_type type;
     };

When the plugin is installed, the plugin name and the `name' value are
joined with an underscore to form the name displayed by `SHOW STATUS'.

The following table shows the allowable status variable `type' values
and what the corresponding variable should be:

*Type*                 *Meaning*
`SHOW_BOOL'            Pointer to a boolean variable
`SHOW_INT'             Pointer to an integer variable
`SHOW_LONG'            Pointer to a long integer variable
`SHOW_LONGLONG'        Pointer to a longlong integer variable
`SHOW_CHAR'            A string
`SHOW_CHAR_PTR'        Pointer to a string
`SHOW_ARRAY'           Pointer to another `st_mysql_show_var' array
`SHOW_FUNC'            Pointer to a function

For the `SHOW_FUNC' type, the function is called and fills in its `out'
parameter, which then provides information about the variable to be
displayed. The function has this signature:

     #define SHOW_VAR_FUNC_BUFF_SIZE 1024

     typedef int (*mysql_show_var_func) (void *thd,
                                         struct st_mysql_show_var *out,
                                         char *buf);

Plugins should consider the `thd' parameter to be read only.


File: manual.info,  Node: plugin-api-type-specific,  Next: plugin-creating,  Prev: plugin-api-general,  Up: plugin-writing

31.2.3.2 Type-Specific Plugin Structures and Functions
......................................................

In the `st_mysql_plugin' structure that defines a plugin's general
declaration, the `info' member points to a type-specific plugin
descriptor. For a full-text parser plugin, the descriptor corresponds
to the `st_mysql_ftparser' structure in the `plugin.h' file:

     struct st_mysql_ftparser
     {
       int interface_version;
       int (*parse)(MYSQL_FTPARSER_PARAM *param);
       int (*init)(MYSQL_FTPARSER_PARAM *param);
       int (*deinit)(MYSQL_FTPARSER_PARAM *param);
     };

As shown by the structure definition, the descriptor has a version
number (`MYSQL_FTPARSER_INTERFACE_VERSION' for full-text parser
plugins) and contains pointers to three functions. The `init' and
`deinit' members should point to a function or be set to 0 if the
function is not needed. The `parse' member must point to the function
that performs the parsing.

A full-text parser plugin is used in two different contexts, indexing
and searching. In both contexts, the server calls the initialization
and deinitialization functions at the beginning and end of processing
each SQL statement that causes the plugin to be invoked. However,
during statement processing, the server calls the main parsing function
in context-specific fashion:

   * For indexing, the server calls the parser for each column value to
     be indexed.

   * For searching, the server calls the parser to parse the search
     string. The parser might also be called for rows processed by the
     statement. In natural language mode, there is no need for the
     server to call the parser. For boolean mode phrase searches or
     natural language searches with query expansion, the parser is used
     to parse column values for information that is not in the index.
     Also, if a boolean mode search is done for a column that has no
     `FULLTEXT' index, the built-in parser will be called. (Plugins are
     associated with specific indexes. If there is no index, no plugin
     is used.)

Note that the plugin declaration in the plugin library descriptor has
initialization and deinitialization functions, and so does the plugin
descriptor to which it points. These pairs of functions have different
purposes and are invoked for different reasons:

   * For the plugin declaration in the plugin library descriptor, the
     initialization and deinitialization functions are invoked when the
     plugin is loaded and unloaded.

   * For the plugin descriptor, the initialization and deinitialization
     functions are invoked per SQL statement for which the plugin is
     used.

Each interface function named in the plugin descriptor should return
zero for success or non-zero for failure, and each of them receives an
argument that points to a `MYSQL_FTPARSER_PARAM' structure containing
the parsing context. The structure has this definition:

     typedef struct st_mysql_ftparser_param
     {
       int (*mysql_parse)(struct st_mysql_ftparser_param *,
                          char *doc, int doc_len);
       int (*mysql_add_word)(struct st_mysql_ftparser_param *,
                             char *word, int word_len,
                             MYSQL_FTPARSER_BOOLEAN_INFO *boolean_info);
       void *ftparser_state;
       void *mysql_ftparam;
       struct charset_info_st *cs;
       char *doc;
       int length;
       int flags;
       enum enum_ftparser_mode mode;
     } MYSQL_FTPARSER_PARAM;

*Note*:

The definition shown is current as of MySQL 5.1.12. It is incompatible
with versions of MySQL 5.1 older than 5.1.12.

The structure members are used as follows:

   * `mysql_parse'

     A pointer to a callback function that invokes the server's
     built-in parser. Use this callback when the plugin acts as a front
     end to the built-in parser. That is, when the plugin parsing
     function is called, it should process the input to extract the
     text and pass the text to the `mysql_parse' callback.

     The first parameter for this callback function should be the
     `param' value itself:

          param->mysql_parse(param, ...);

     A front end plugin can extract text and pass it all at once to the
     built-in parser, or it can extract and pass text to the built-in
     parser a piece at a time. However, in this case, the built-in
     parser treats the pieces of text as though there are implicit word
     breaks between them.

   * `mysql_add_word'

     A pointer to a callback function that adds a word to a full-text
     index or to the list of search terms. Use this callback when the
     parser plugin replaces the built-in parser. That is, when the
     plugin parsing function is called, it should parse the input into
     words and invoke the `mysql_add_word' callback for each word.

     The first parameter for this callback function should be the
     `param' value itself:

          param->mysql_add_word(param, ...);

   * `ftparser_state'

     This is a generic pointer. The plugin can set it to point to
     information to be used internally for its own purposes.

   * `mysql_ftparam'

     This is set by the server. It is passed as the first argument to
     the `mysql_parse' or `mysql_add_word' callback.

   * `cs'

     A pointer to information about the character set of the text, or 0
     if no information is available.

   * `doc'

     A pointer to the text to be parsed.

   * `length'

     The length of the text to be parsed, in bytes.

   * `flags'

     Parser flags. This is zero if there are no special flags.
     Currently, the only non-zero flag is `MYSQL_FTFLAGS_NEED_COPY',
     which means that `mysql_add_word()' must save a copy of the word
     (that is, it cannot use a pointer to the word because the word is
     in a buffer that will be overwritten.) This member was added in
     MySQL 5.1.12.

     This flag might be set or reset by MySQL before calling the parser
     plugin, by the parser plugin itself, or by the `mysql_parse()'
     function.

   * `mode'

     The parsing mode. This value will be one of the folowing constants:

        * `MYSQL_FTPARSER_SIMPLE_MODE'

          Parse in fast and simple mode, which is used for indexing and
          for natural language queries. The parser should pass to the
          server only those words that should be indexed. If the parser
          uses length limits or a stopword list to determine which
          words to ignore, it should not pass such words to the server.

        * `MYSQL_FTPARSER_WITH_STOPWORDS'

          Parse in stopword mode. This is used in boolean searches for
          phrase matching. The parser should pass all words to the
          server, even stopwords or words that are outside any normal
          length limits.

        * `MYSQL_FTPARSER_FULL_BOOLEAN_INFO'

          Parse in boolean mode. This is used for parsing boolean query
          strings. The parser should recognize not only words but also
          boolean-mode operators and pass them to the server as tokens
          via the `mysql_add_word' callback. To tell the server what
          kind of token is being passed, the plugin needs to fill in a
          `MYSQL_FTPARSER_BOOLEAN_INFO' structure and pass a pointer to
          it.

If the parser is called in boolean mode, the `param->mode' value will be
`MYSQL_FTPARSER_FULL_BOOLEAN_INFO'. The `MYSQL_FTPARSER_BOOLEAN_INFO'
structure that the parser uses for passing token information to the
server looks like this:

     typedef struct st_mysql_ftparser_boolean_info
     {
       enum enum_ft_token_type type;
       int yesno;
       int weight_adjust;
       bool wasign;
       bool trunc;
       /* These are parser state and must be removed. */
       byte prev;
       byte *quot;
     } MYSQL_FTPARSER_BOOLEAN_INFO;

The parser should fill in the structure members as follows:

   * `type'

     The token type. This should be one of values shown in the
     following table:

     *Type*                      *Meaning*
     `FT_TOKEN_EOF'              End of data
     `FT_TOKEN_WORD'             A regular word
     `FT_TOKEN_LEFT_PAREN'       The beginning of a group or
                                 subexpression
     `FT_TOKEN_RIGHT_PAREN'      The end of a group or subexpression
     `FT_TOKEN_STOPWORD'         A stopword

   * `yesno'

     Whether the word must be present for a match to occur. 0 means
     that the word is optional but increases the match relevance if it
     is present. Values larger than 0 mean that the word must be
     present. Values smaller than 0 mean that the word must not be
     present.

   * `weight_adjust'

     A weighting factor that determines how much a match for the word
     counts. It can be used to increase or decrease the word's
     importance in relevance calculations. A value of zero indicates no
     weight adjustment. Values greater than or less than zero mean
     higher or lower weight, respectively. The examples at *Note
     fulltext-boolean::, that use the `<' and `>' operators illustrate
     how weighting works.

   * `wasign'

     The sign of the weighting factor. A negative value acts like the
     `~' boolean-search operator, which causes the word's contribution
     to the relevance to be negative.

   * `trunc'

     Whether matching should be done as if the boolean-mode `*'
     truncation operator had been given.

Plugins should not use the `prev' and `quot' members of the
`MYSQL_FTPARSER_BOOLEAN_INFO' structure.


File: manual.info,  Node: plugin-creating,  Prev: plugin-api-type-specific,  Up: plugin-writing

31.2.3.3 Creating a Plugin Library
..................................

This section provides a step-by-step procedure for creating a plugin
library. It shows how to develop a library that contains a full-text
parsing plugin named `simple_parser'. This plugin performs parsing
based on simpler rules than those used by the MySQL built-in full-text
parser: Words are non-empty runs of whitespace characters.

Each plugin library has the following contents:

   * A plugin library descriptor that indicates the version number of
     the general plugin API that the library uses and that contains a
     general declaration for each plugin in the library.

   * Each plugin general declaration contains information that is
     common to all types of plugin: A value that indicates the plugin
     type; the plugin name, author, description, and license type; and
     pointers to the initialization and deinitialization functions that
     the server invokes when it loads and unloads the plugin.

   * The plugin general declaration also contains a pointer to a
     type-specific plugin descriptor. The structure of these
     descriptors can vary from one plugin type to another, because each
     type of plugin can have its own API. A plugin descriptor contains
     a type-specific API version number and pointers to the functions
     that are needed to implement that plugin type. For example, a
     full-text parser plugin has initialization and deinitialization
     functions, and a main parsing function. The server invokes these
     functions when it uses the plugin to parse text.

   * The plugin library contains the interface functions that are
     referenced by the library descriptor and by the plugin descriptors.

The easiest way to follow the instructions in this section is to use
the source code in the `plugin/fulltext' directory of a MySQL source
distribution. The instructions assume that you make a copy of that
directory and use it to build the plugin library.  To make a copy of
the directory, use the following commands, which assume that the MySQL
source tree is in a directory named `mysql-5.1' under your current
directory:

     shell> mkdir fulltext_plugin
     shell> cp mysql-5.1/plugin/fulltext/* fulltext_plugin

After copying the source files, use the following procedure to create a
plugin library:

  1. Change location into the `fulltext_plugin' directory:

          shell> cd fulltext_plugin

  2. The plugin source file should include the header files that the
     plugin library needs. The `plugin.h' file is required, and the
     library might require other files as well. For example:

          #include <stdlib.h>
          #include <ctype.h>
          #include <mysql/plugin.h>

  3. Set up the plugin library file descriptor.

     Every plugin library must include a library descriptor that must
     define two symbols:

        * `_mysql_plugin_interface_version_' specifies the version
          number of the general plugin framework. This is given by the
          `MYSQL_PLUGIN_INTERFACE_VERSION' symbol, which is defined in
          the `plugin.h' file.

        * `_mysql_plugin_declarations_' defines an array of plugin
          declarations, terminated by a declaration with all members
          set to 0. Each declaration is an instance of the
          `st_mysql_plugin' structure (also defined in `plugin.h').
          There must be one of these for each plugin in the library.

     If the server does not find these two symbols in a library, it
     does not accept it as a legal plugin library and rejects it with
     an error. This prevents use of a library for plugin purposes
     unless it was built specifically as a plugin library.

     The standard (and most convenient) way to define the two required
     symbols is by using the `mysql_declare_plugin' and
     `mysql_declare_plugin_end' macros from the `plugin.h' file:

          mysql_declare_plugin
           ... ONE OR MORE PLUGIN DECLARATIONS HERE ...
          mysql_declare_plugin_end;

     For example, the library descriptor for a library that contains a
     single plugin named `simple_parser' looks like this:

          mysql_declare_plugin
          {
            MYSQL_FTPARSER_PLUGIN,      /* type                            */
            &simple_parser_descriptor,  /* descriptor                      */
            "simple_parser",            /* name                            */
            "MySQL AB",                 /* author                          */
            "Simple Full-Text Parser",  /* description                     */
            PLUGIN_LICENSE_GPL,         /* plugin license                  */
            simple_parser_plugin_init,  /* init function (when loaded)     */
            simple_parser_plugin_deinit,/* deinit function (when unloaded) */
            0x0001,                     /* version                         */
            simple_status               /* status variables                */
          }
          mysql_declare_plugin_end;

     For a full-text parser plugin, the type must be
     `MYSQL_FTPARSER_PLUGIN'. This is the value that identifies the
     plugin as being legal for use in a `WITH PARSER' clause when
     creating a `FULLTEXT' index. (No other plugin type is legal for
     this clause.)

     The `mysql_declare_plugin' and `mysql_declare_plugin_end' macros
     are defined in `plugin.h' like this:

          #ifndef MYSQL_DYNAMIC_PLUGIN
          #define __MYSQL_DECLARE_PLUGIN(NAME, VERSION, PSIZE, DECLS)           \
          int VERSION= MYSQL_PLUGIN_INTERFACE_VERSION;                          \
          int PSIZE= sizeof(struct st_mysql_plugin);                            \
          struct st_mysql_plugin DECLS[]= {
          #else
          #define __MYSQL_DECLARE_PLUGIN(NAME, VERSION, PSIZE, DECLS)           \
          int _mysql_plugin_interface_version_= MYSQL_PLUGIN_INTERFACE_VERSION; \
          int _mysql_sizeof_struct_st_plugin_= sizeof(struct st_mysql_plugin);  \
          struct st_mysql_plugin _mysql_plugin_declarations_[]= {
          #endif

          #define mysql_declare_plugin(NAME) \
          __MYSQL_DECLARE_PLUGIN(NAME, \
                           builtin_ ## NAME ## _plugin_interface_version, \
                           builtin_ ## NAME ## _sizeof_struct_st_plugin, \
                           builtin_ ## NAME ## _plugin)

          #define mysql_declare_plugin_end ,{0,0,0,0,0,0,0,0,0}}

     One point to note about those definitions is that the
     `_mysql_plugin_interface_version_' symbol is defined only if the
     `MYSQL_DYNAMIC_PLUGIN' symbol is defined.  This means that you'll
     need to provide `-DMYSQL_DYNAMIC_PLUGIN' as part of the
     compilation command when you build the plugin.

     When the macros are used as just shown, they expand to the
     following code, which defines both of the required symbols
     (`_mysql_plugin_interface_version_' and
     `_mysql_plugin_declarations_'):

          int _mysql_plugin_interface_version_= MYSQL_PLUGIN_INTERFACE_VERSION;
          struct st_mysql_plugin _mysql_plugin_declarations_[]= {
          {
            MYSQL_FTPARSER_PLUGIN,      /* type                            */
            &simple_parser_descriptor,  /* descriptor                      */
            "simple_parser",            /* name                            */
            "MySQL AB",                 /* author                          */
            "Simple Full-Text Parser",  /* description                     */
            PLUGIN_LICENSE_GPL,         /* plugin license                  */
            simple_parser_plugin_init,  /* init function (when loaded)     */
            simple_parser_plugin_deinit,/* deinit function (when unloaded) */
            0x0001,                     /* version                         */
            simple_status               /* status variables                */
          }
            ,{0,0,0,0,0,0,00,0}
          };

     The preceding example declares a single plugin in the library
     descriptor, but it is possible to declare multiple plugins. List
     the declarations one after the other between
     `mysql_declare_plugin' and `mysql_declare_plugin_end', separated by
     commas.

     MySQL plugins can be written in C or C++ (or another language that
     can use C calling conventions). One feature of C++ is that you can
     use non-constant variables to initialize global structures.
     However, if you write a C++ plugin, you should not use this
     feature. Members of structures such as the `st_mysql_plugin'
     structure should be initialized with constant variables.  See the
     discussion at the end of this section that describes some legal
     and illegal initializers for plugins.

  4. Set up the plugin descriptor.

     Each plugin declaration in the library descriptor points to a
     type-specific descriptor for the corresponding plugin. In the
     `simple_parser' declaration, that descriptor is indicated by
     `&simple_parser_descriptor'. The descriptor specifies the version
     number for the full-text plugin interface (as given by
     `MYSQL_FTPARSER_INTERFACE_VERSION'), and the plugin's parsing,
     initialization, and deinitialization functions:

          static struct st_mysql_ftparser simple_parser_descriptor=
          {
            MYSQL_FTPARSER_INTERFACE_VERSION, /* interface version      */
            simple_parser_parse,              /* parsing function       */
            simple_parser_init,               /* parser init function   */
            simple_parser_deinit              /* parser deinit function */
          };

  5. Set up the plugin interface functions.

     The general plugin declaration in the library descriptor names the
     initialization and deinitialization functions that the server
     should invoke when it loads and unloads the plugin. For
     `simple_parser', these functions do nothing but return zero to
     indicate that they succeeded:

          static int simple_parser_plugin_init(void)
          {
            return(0);
          }

          static int simple_parser_plugin_deinit(void)
          {
            return(0);
          }

     Because those functions do not actually do anything, you could
     omit them and specify 0 for each of them in the plugin declaration.

     The type-specific plugin descriptor for `simple_parser' names the
     initialization, deinitialization, and parsing functions that the
     server invokes when the plugin is used. For `simple_parser', the
     initialization and deinitialization functions do nothing:

          static int simple_parser_init(MYSQL_FTPARSER_PARAM *param)
          {
            return(0);
          }

          static int simple_parser_deinit(MYSQL_FTPARSER_PARAM *param)
          {
            return(0);
          }

     Here too, because those functions do nothing, you could omit them
     and specify 0 for each of them in the plugin descriptor.

     The main parsing function, `simple_parser_parse()', acts as a
     replacement for the built-in full-text parser, so it needs to
     split text into words and pass each word to the server.  The
     parsing function's first argument is a pointer to a structure that
     contains the parsing context. This structure has a `doc' member
     that points to the text to be parsed, and a `length' member that
     indicates how long the text is. The simple parsing done by the
     plugin considers non-empty runs of whitespace characters to be
     words, so it identifies words like this:

          static int simple_parser_parse(MYSQL_FTPARSER_PARAM *param)
          {
            char *end, *start, *docend= param->doc + param->length;

            for (end= start= param->doc;; end++)
            {
              if (end == docend)
              {
                if (end > start)
                  add_word(param, start, end - start);
                break;
              }
              else if (isspace(*end))
              {
                if (end > start)
                  add_word(param, start, end - start);
                start= end + 1;
              }
            }
            return(0);
          }

     As the parser finds each word, it invokes a function `add_word()'
     to pass the word to the server. `add_word()' is a helper function
     only; it is not part of the plugin interface. The parser passes
     the parsing context pointer to `add_word()', as well as a pointer
     to the word and a length value:

          static void add_word(MYSQL_FTPARSER_PARAM *param, char *word, size_t len)
          {
            MYSQL_FTPARSER_BOOLEAN_INFO bool_info=
              { FT_TOKEN_WORD, 0, 0, 0, 0, ' ', 0 };

            param->mysql_add_word(param, word, len, &bool_info);
          }

     For boolean-mode parsing, `add_word()' fills in the members of the
     `bool_info' structure as described in *Note
     plugin-api-type-specific::.

  6. Set up the status variables, if there are any. For the
     `simple_parser' plugin, the following status variable array sets
     up one status variable with a value that is static text, and
     another with a value that is stored in a long integer variable:

          long number_of_calls= 0;

          struct st_mysql_show_var simple_status[]=
          {
            {"static", (char *)"just a static text", SHOW_CHAR},
            {"called", (char *)&number_of_calls,     SHOW_LONG},
            {0,0,0}
          };

     When the plugin is installed, the plugin name and the `name' value
     are joined with an underscore to form the name displayed by `SHOW
     STATUS'. For the array just shown, the resulting status variable
     names are `simple_parser_static' and `simple_parser_called'. This
     convention means that you can easily display the variables for a
     plugin using its name:

          mysql> SHOW STATUS LIKE 'simple_parser%';
          +----------------------+--------------------+
          | Variable_name        | Value              |
          +----------------------+--------------------+
          | simple_parser_static | just a static text |
          | simple_parser_called | 0                  |
          +----------------------+--------------------+

  7. Compile the plugin library as a shared library and install it in
     the plugin directory.

     *Note*:

     As mentioned earlier, be sure to specify `-DMYSQL_DYNAMIC_PLUGIN'
     as part of the compilation command when you build the plugin.

     The procedure for compiling shared objects varies from system to
     system. If you build your library using the GNU autotools,
     `libtool' should be able to generate the correct compilation
     commands for your system.  If the library is named `mypluglib', you
     should end up with a shared object file that has a name something
     like `libmypluglib.so'. (The filename might have a different
     extension on your system.)

     To use the autotools, you'll need to make a few changes to the
     configuration files at this point to enable the plugin to be
     compiled and installed. Assume that your MySQL distribution is
     installed at a base directory of `/usr/local/mysql' and that its
     header files are located in the `include' directory under the base
     directory.

     Edit `Makefile.am', which should look something like this:

          #Makefile.am example for a plugin

          pkglibdir=$(libdir)/mysql
          INCLUDES= -I$(top_builddir)/include -I$(top_srcdir)/include
          #noinst_LTLIBRARIES= mypluglib.la
          pkglib_LTLIBRARIES= mypluglib.la
          mypluglib_la_SOURCES= plugin_example.c
          mypluglib_la_LDFLAGS= -module -rpath $(pkglibdir)
          mypluglib_la_CFLAGS= -DMYSQL_DYNAMIC_PLUGIN

     The `mypluglib_la_CFLAGS' line takes care of passing the
     `-DMYSQL_DYNAMIC_PLUGIN' flag to the compilation command.

     Adjust the `INCLUDES' line to specify the pathname to the
     installed MySQL header files. Edit it to look like this:

          INCLUDES= -I/usr/local/mysql/include

     Make sure that the `noinst_LTLIBRARIES' line is commented out or
     remove it. Make sure that the `pkglib_LTLIBRARIES' line is not
     commented out; it enables the `make install' command.

     Set up the files needed for the `configure' command, invoke it,
     and run `make':

          shell> autoreconf --force --install --symlink
          shell> ./configure --prefix=/usr/local/mysql
          shell> make

     The `--prefix' option to `configure' indicates the MySQL base
     directory under which the plugin should be installed. You can see
     what value to use for this option with `SHOW VARIABLES':

          mysql> SHOW VARIABLES LIKE 'basedir';
          +---------------+------------------+
          | Variable_name | Value            |
          +---------------+------------------+
          | base          | /usr/local/mysql |
          +---------------+------------------+

     The location of the plugin directory where you should install the
     library is given by the `plugin_dir' system variable. For example:

          mysql> SHOW VARIABLES LIKE 'plugin_dir';
          +---------------+-----------------------------------+
          | Variable_name | Value                             |
          +---------------+-----------------------------------+
          | plugin_dir    | /usr/local/mysql/lib/mysql/plugin |
          +---------------+-----------------------------------+

     To install the plugin library, use `make':

          shell> make install

     Verify that `make install' installed the plugin library in the
     proper directory. After installing it, make sure that the library
     permissions allow it to be executed by the server.

  8. Register the plugin with the server.

     The `INSTALL PLUGIN' statement causes the server to list the
     plugin in the `plugin' table and to load the plugin code from the
     library file.  Use that statement to register `simple_parser' with
     the server, and then verify that the plugin is listed in the
     `plugin' table:

          mysql> INSTALL PLUGIN simple_parser SONAME 'libmypluglib.so';
          Query OK, 0 rows affected (0.00 sec)

          mysql> SELECT * FROM mysql.plugin;
          +---------------+-----------------+
          | name          | dl              |
          +---------------+-----------------+
          | simple_parser | libmypluglib.so |
          +---------------+-----------------+
          1 row in set (0.00 sec)

  9. Try the plugin.

     Create a table that contains a string column and associate the
     parser plugin with a `FULLTEXT' index on the column:

          mysql> CREATE TABLE t (c VARCHAR(255),
              ->   FULLTEXT (c) WITH PARSER simple_parser);
          Query OK, 0 rows affected (0.01 sec)

     Insert some text into the table and try some searches.  These
     should verify that the parser plugin treats all non-whitespace
     characters as word characters:

          mysql> INSERT INTO t VALUES
              ->   ('latin1_general_cs is a case-sensitive collation'),
              ->   ('I\'d like a case of oranges'),
              ->   ('this is sensitive information'),
              ->   ('another row'),
              ->   ('yet another row');
          Query OK, 5 rows affected (0.02 sec)
          Records: 5  Duplicates: 0  Warnings: 0

          mysql> SELECT c FROM t;
          +-------------------------------------------------+
          | c                                               |
          +-------------------------------------------------+
          | latin1_general_cs is a case-sensitive collation |
          | I'd like a case of oranges                      |
          | this is sensitive information                   |
          | another row                                     |
          | yet another row                                 |
          +-------------------------------------------------+
          5 rows in set (0.00 sec)

          mysql> SELECT MATCH(c) AGAINST('case') FROM t;
          +--------------------------+
          | MATCH(c) AGAINST('case') |
          +--------------------------+
          |                        0 |
          |          1.2968142032623 |
          |                        0 |
          |                        0 |
          |                        0 |
          +--------------------------+
          5 rows in set (0.00 sec)

          mysql> SELECT MATCH(c) AGAINST('sensitive') FROM t;
          +-------------------------------+
          | MATCH(c) AGAINST('sensitive') |
          +-------------------------------+
          |                             0 |
          |                             0 |
          |               1.3253291845322 |
          |                             0 |
          |                             0 |
          +-------------------------------+
          5 rows in set (0.01 sec)

          mysql> SELECT MATCH(c) AGAINST('case-sensitive') FROM t;
          +------------------------------------+
          | MATCH(c) AGAINST('case-sensitive') |
          +------------------------------------+
          |                    1.3109166622162 |
          |                                  0 |
          |                                  0 |
          |                                  0 |
          |                                  0 |
          +------------------------------------+
          5 rows in set (0.01 sec)

          mysql> SELECT MATCH(c) AGAINST('I\'d') FROM t;
          +--------------------------+
          | MATCH(c) AGAINST('I\'d') |
          +--------------------------+
          |                        0 |
          |          1.2968142032623 |
          |                        0 |
          |                        0 |
          |                        0 |
          +--------------------------+
          5 rows in set (0.01 sec)

Note how neither `case' nor `insensitive' match `case-insensitive' the
way that they would for the built-in parser.

MySQL plugins can be written in C or C++ (or another language that can
use C calling conventions). One feature of C++ is that you can use
non-constant variables to initialize global structures. However, if you
write a C++ plugin, you should not use this feature. Members of
structures such as the `st_mysql_plugin' structure should be
initialized with constant variables. The `simple_parser' descriptor
shown earlier is allowable in a C++ plugin because it satisfies that
requirement:

     mysql_declare_plugin
     {
       MYSQL_FTPARSER_PLUGIN,      /* type                            */
       &simple_parser_descriptor,  /* descriptor                      */
       "simple_parser",            /* name                            */
       "MySQL AB",                 /* author                          */
       "Simple Full-Text Parser",  /* description                     */
       PLUGIN_LICENSE_GPL,         /* plugin license                  */
       simple_parser_plugin_init,  /* init function (when loaded)     */
       simple_parser_plugin_deinit,/* deinit function (when unloaded) */
       0x0001,                     /* version                         */
       simple_status               /* status variables                */
     }
     mysql_declare_plugin_end;

Here is another valid way to write the descriptor. It uses constant
variables to indicate the plugin name, author, and description:

     const char *simple_parser_name = "simple_parser";
     const char *simple_parser_author = "MySQL AB";
     const char *simple_parser_description = "Simple Full-Text Parser";

     mysql_declare_plugin
     {
       MYSQL_FTPARSER_PLUGIN,      /* type                            */
       &simple_parser_descriptor,  /* descriptor                      */
       simple_parser_name,         /* name                            */
       simple_parser_author,       /* author                          */
       simple_parser_description,  /* description                     */
       PLUGIN_LICENSE_GPL,         /* plugin license                  */
       simple_parser_plugin_init,  /* init function (when loaded)     */
       simple_parser_plugin_deinit,/* deinit function (when unloaded) */
       0x0001,                     /* version                         */
       simple_status               /* status variables                */
     }
     mysql_declare_plugin_end;

However, the following descriptor is invalid. It uses structure members
to indicate the plugin name, author, and description, but structures
are not considered constant initializers in C++:

     typedef struct
     {
       const char *name;
       const char *author;
       const char *description;
     } plugin_info;

     plugin_info parser_info = {
       "simple_parser",
       "MySQL AB",
       "Simple Full-Text Parser"
     };

     mysql_declare_plugin
     {
       MYSQL_FTPARSER_PLUGIN,      /* type                            */
       &simple_parser_descriptor,  /* descriptor                      */
       parser_info.name,           /* name                            */
       parser_info.author,         /* author                          */
       parser_info.description,    /* description                     */
       PLUGIN_LICENSE_GPL,         /* plugin license                  */
       simple_parser_plugin_init,  /* init function (when loaded)     */
       simple_parser_plugin_deinit,/* deinit function (when unloaded) */
       0x0001,                     /* version                         */
       simple_status               /* status variables                */
     }
     mysql_declare_plugin_end;


File: manual.info,  Node: adding-functions,  Next: adding-procedures,  Prev: plugin-api,  Up: extending-mysql

31.3 Adding New Functions to MySQL
==================================

* Menu:

* udf-features::                 Features of the User-Defined Function Interface
* adding-udf::                   Adding a New User-Defined Function
* adding-native-function::       Adding a New Native Function

There are three ways to add new functions to MySQL:

   * You can add functions through the user-defined function (UDF)
     interface. User-defined functions are compiled as object files and
     then added to and removed from the server dynamically using the
     `CREATE FUNCTION' and `DROP FUNCTION' statements. See *Note
     create-function-udf::.

   * You can add functions as native (built-in) MySQL functions.
     Native functions are compiled into the `mysqld' server and become
     available on a permanent basis.

   * Another way to add functions is by creating stored functions.
     These are written using SQL statements rather than by compiling
     object code. The syntax for writing stored functions is not
     covered here. See *Note stored-procedures::.

Each method of creating compiled functions has advantages and
disadvantages:

   * If you write user-defined functions, you must install object files
     in addition to the server itself. If you compile your function
     into the server, you don't need to do that.

   * Native functions require you to modify a source distribution.
     UDFs do not. You can add UDFs to a binary MySQL distribution.  No
     access to MySQL source is necessary.

   * If you upgrade your MySQL distribution, you can continue to use
     your previously installed UDFs, unless you upgrade to a newer
     version for which the UDF interface changes. For native functions,
     you must repeat your modifications each time you upgrade.

Whichever method you use to add new functions, they can be invoked in
SQL statements just like native functions such as `ABS()' or
`SOUNDEX()'.

See *Note function-resolution::, for the rules describing how the
server interprets references to different kinds of functions.

The following sections describe features of the UDF interface, provide
instructions for writing UDFs, discuss security precautions that MySQL
takes to prevent UDF misuse, and describe how to add native MySQL
functions.

For example source code that illustrates how to write UDFs, take a look
at the `sql/udf_example.c' file that is provided in MySQL source
distributions.


File: manual.info,  Node: udf-features,  Next: adding-udf,  Prev: adding-functions,  Up: adding-functions

31.3.1 Features of the User-Defined Function Interface
------------------------------------------------------

The MySQL interface for user-defined functions provides the following
features and capabilities:

   * Functions can return string, integer, or real values and can
     accept arguments of those same types.

   * You can define simple functions that operate on a single row at a
     time, or aggregate functions that operate on groups of rows.

   * Information is provided to functions that enables them to check
     the number, types, and names of the arguments passed to them.

   * You can tell MySQL to coerce arguments to a given type before
     passing them to a function.

   * You can indicate that a function returns `NULL' or that an error
     occurred.


File: manual.info,  Node: adding-udf,  Next: adding-native-function,  Prev: udf-features,  Up: adding-functions

31.3.2 Adding a New User-Defined Function
-----------------------------------------

* Menu:

* udf-calling::                  UDF Calling Sequences for Simple Functions
* udf-aggr-calling::             UDF Calling Sequences for Aggregate Functions
* udf-arguments::                UDF Argument Processing
* udf-return-values::            UDF Return Values and Error Handling
* udf-compiling::                Compiling and Installing User-Defined Functions
* udf-security::                 User-Defined Function Security Precautions

For the UDF mechanism to work, functions must be written in C or C++
and your operating system must support dynamic loading. The MySQL
source distribution includes a file `sql/udf_example.c' that defines 5
new functions. Consult this file to see how UDF calling conventions
work. UDF-related symbols and data structures are defined in the
`include/mysql_com.h' header file. (You need not include this header
file directly because it is included by `mysql.h'.)

A UDF contains code that becomes part of the running server, so when
you write a UDF, you are bound by any and all constraints that
otherwise apply to writing server code. For example, you may have
problems if you attempt to use functions from the `libstdc++' library.
These constraints may change in future versions of the server, so it is
possible that server upgrades will require revisions to UDFs that were
originally written for older servers. For information about these
constraints, see *Note configure-options::, and *Note
compilation-problems::.

To be able to use UDFs, you need to link `mysqld' dynamically. Don't
configure MySQL using `--with-mysqld-ldflags=-all-static'. If you want
to use a UDF that needs to access symbols from `mysqld' (for example,
the `metaphone' function in `sql/udf_example.c' that uses
`default_charset_info'), you must link the program with `-rdynamic'
(see `man dlopen'). If you plan to use UDFs, the rule of thumb is to
configure MySQL with `--with-mysqld-ldflags=-rdynamic' unless you have
a very good reason not to.

For each function that you want to use in SQL statements, you should
define corresponding C (or C++) functions. In the following discussion,
the name `xxx' is used for an example function name. To distinguish
between SQL and C/C++ usage, `XXX()' (uppercase) indicates an SQL
function call, and `xxx()' (lowercase) indicates a C/C++ function call.

The C/C++ functions that you write to implement the interface for
`XXX()' are:

   * `xxx()' (required)

     The main function. This is where the function result is computed.
     The correspondence between the SQL function data type and the
     return type of your C/C++ function is shown here:

     *SQL Type*        *C/C++ Type*
     `STRING'          `char *'
     `INTEGER'         `long long'
     `REAL'            `double'

     It is also possible to declare a `DECIMAL' function, but currently
     the value is returned as a string, so you should write the UDF as
     though it were a `STRING' function. `ROW' functions are not
     implemented.

   * `xxx_init()' (optional)

     The initialization function for `xxx()'. It can be used for the
     following purposes:

        * To check the number of arguments to `XXX()'.

        * To check that the arguments are of a required type or,
          alternatively, to tell MySQL to coerce arguments to the types
          you want when the main function is called.

        * To allocate any memory required by the main function.

        * To specify the maximum length of the result.

        * To specify (for `REAL' functions) the maximum number of
          decimal places in the result.

        * To specify whether the result can be `NULL'.

   * `xxx_deinit()' (optional)

     The deinitialization function for `xxx()'.  It should deallocate
     any memory allocated by the initialization function.

When an SQL statement invokes `XXX()', MySQL calls the initialization
function `xxx_init()' to let it perform any required setup, such as
argument checking or memory allocation. If `xxx_init()' returns an
error, MySQL aborts the SQL statement with an error message and does
not call the main or deinitialization functions.  Otherwise, MySQL
calls the main function `xxx()' once for each row. After all rows have
been processed, MySQL calls the deinitialization function
`xxx_deinit()' so that it can perform any required cleanup.

For aggregate functions that work like `SUM()', you must also provide
the following functions:

   * `xxx_clear()'

     Reset the current aggregate value but do not insert the argument
     as the initial aggregate value for a new group.

   * `xxx_add()'

     Add the argument to the current aggregate value.

MySQL handles aggregate UDFs as follows:

  1. Call `xxx_init()' to let the aggregate function allocate any
     memory it needs for storing results.

  2. Sort the table according to the `GROUP BY' expression.

  3. Call `xxx_clear()' for the first row in each new group.

  4. Call `xxx_add()' for each row that belongs in the same group.

  5. Call `xxx()' to get the result for the aggregate when the group
     changes or after the last row has been processed.

  6. Repeat 3-5 until all rows has been processed

  7. Call `xxx_deinit()' to let the UDF free any memory it has
     allocated.

All functions must be thread-safe. This includes not just the main
function, but the initialization and deinitialization functions as
well, and also the additional functions required by aggregate
functions. A consequence of this requirement is that you are not
allowed to allocate any global or static variables that change! If you
need memory, you should allocate it in `xxx_init()' and free it in
`xxx_deinit()'.


File: manual.info,  Node: udf-calling,  Next: udf-aggr-calling,  Prev: adding-udf,  Up: adding-udf

31.3.2.1 UDF Calling Sequences for Simple Functions
...................................................

This section describes the different functions that you need to define
when you create a simple UDF.  *Note adding-udf::, describes the order
in which MySQL calls these functions.

The main `xxx()' function should be declared as shown in this section.
Note that the return type and parameters differ, depending on whether
you declare the SQL function `XXX()' to return `STRING', `INTEGER', or
`REAL' in the `CREATE FUNCTION' statement:

For `STRING' functions:

     char *xxx(UDF_INIT *initid, UDF_ARGS *args,
               char *result, unsigned long *length,
               char *is_null, char *error);

For `INTEGER' functions:

     long long xxx(UDF_INIT *initid, UDF_ARGS *args,
                   char *is_null, char *error);

For `REAL' functions:

     double xxx(UDF_INIT *initid, UDF_ARGS *args,
                   char *is_null, char *error);

`DECIMAL' functions return string values and should be declared the
same way as `STRING' functions. `ROW' functions are not implemented.

The initialization and deinitialization functions are declared like
this:

     my_bool xxx_init(UDF_INIT *initid, UDF_ARGS *args, char *message);

     void xxx_deinit(UDF_INIT *initid);

The `initid' parameter is passed to all three functions. It points to a
`UDF_INIT' structure that is used to communicate information between
functions. The `UDF_INIT' structure members follow. The initialization
function should fill in any members that it wishes to change. (To use
the default for a member, leave it unchanged.)

   * `my_bool maybe_null'

     `xxx_init()' should set `maybe_null' to `1' if `xxx()' can return
     `NULL'. The default value is `1' if any of the arguments are
     declared `maybe_null'.

   * `unsigned int decimals'

     The number of decimal digits to the right of the decimal point.
     The default value is the maximum number of decimal digits in the
     arguments passed to the main function. For example, if the
     function is passed `1.34', `1.345', and `1.3', the default would
     be 3, because `1.345' has 3 decimal digits.

     For arguments that have no fixed number of decimals, the
     `decimals' value is set to 31, which is 1 more than the maximum
     number of decimals allowed for the `DECIMAL', `FLOAT', and
     `DOUBLE' data types.

     A `decimals' value of 31 is used for arguments in cases such as a
     `FLOAT' or `DOUBLE' column declared without an explicit number of
     decimals (for example, `FLOAT' rather than `FLOAT(10,3)') and for
     floating-point constants such as `1345E-3'. It is also used for
     string and other non-number arguments that might be converted
     within the function to numeric form.

     The value to which the `decimals' member is initialized is only a
     default. It can be changed within the function to reflect the
     actual calculation performed.  The default is determined such that
     the largest number of decimals of the arguments is used. If the
     number of decimals is 31 for even one of the arguments, that is the
     value used for `decimals'.

   * `unsigned int max_length'

     The maximum length of the result. The default `max_length' value
     differs depending on the result type of the function. For string
     functions, the default is the length of the longest argument. For
     integer functions, the default is 21 digits. For real functions,
     the default is 13 plus the number of decimal digits indicated by
     `initid->decimals'. (For numeric functions, the length includes
     any sign or decimal point characters.)

     If you want to return a blob value, you can set `max_length' to
     65KB or 16MB. This memory is not allocated, but the value is used
     to decide which data type to use if there is a need to temporarily
     store the data.

   * `char *ptr'

     A pointer that the function can use for its own purposes.  For
     example, functions can use `initid->ptr' to communicate allocated
     memory among themselves. `xxx_init()' should allocate the memory
     and assign it to this pointer:

          initid->ptr = allocated_memory;

     In `xxx()' and `xxx_deinit()', refer to `initid->ptr' to use or
     deallocate the memory.

   * `my_bool const_item'

     `xxx_init()' should set `const_item' to `1' if `xxx()' always
     returns the same value and to `0' otherwise.


File: manual.info,  Node: udf-aggr-calling,  Next: udf-arguments,  Prev: udf-calling,  Up: adding-udf

31.3.2.2 UDF Calling Sequences for Aggregate Functions
......................................................

This section describes the different functions that you need to define
when you create an aggregate UDF.  *Note adding-udf::, describes the
order in which MySQL calls these functions.

   * `xxx_reset()'

     This function is called when MySQL finds the first row in a new
     group. It should reset any internal summary variables and then use
     the given `UDF_ARGS' argument as the first value in your internal
     summary value for the group. Declare `xxx_reset()' as follows:

          void xxx_reset(UDF_INIT *initid, UDF_ARGS *args,
                         char *is_null, char *error);

     `xxx_reset()' is not needed or used in MySQL 5.1, in which the UDF
     interface uses `xxx_clear()' instead. However, you can define both
     `xxx_reset()' and `xxx_clear()' if you want to have your UDF work
     with older versions of the server. (If you do include both
     functions, the `xxx_reset()' function in many cases can be
     implemented internally by calling `xxx_clear()' to reset all
     variables, and then calling `xxx_add()' to add the `UDF_ARGS'
     argument as the first value in the group.)

   * `xxx_clear()'

     This function is called when MySQL needs to reset the summary
     results. It is called at the beginning for each new group but can
     also be called to reset the values for a query where there were no
     matching rows. Declare `xxx_clear()' as follows:

          void xxx_clear(UDF_INIT *initid, char *is_null, char *error);

     `is_null' is set to point to `CHAR(0)' before calling
     `xxx_clear()'.

     If something went wrong, you can store a value in the variable to
     which the `error' argument points. `error' points to a single-byte
     variable, not to a string buffer.

     `xxx_clear()' is required by MySQL 5.1.

   * `xxx_add()'

     This function is called for all rows that belong to the same
     group. You should use it to add the value in the `UDF_ARGS'
     argument to your internal summary variable.

          void xxx_add(UDF_INIT *initid, UDF_ARGS *args,
                       char *is_null, char *error);

The `xxx()' function for an aggregate UDF should be declared the same
way as for a non-aggregate UDF.  See *Note udf-calling::.

For an aggregate UDF, MySQL calls the `xxx()' function after all rows
in the group have been processed. You should normally never access its
`UDF_ARGS' argument here but instead return a value based on your
internal summary variables.

Return value handling in `xxx()' should be done the same way as for a
non-aggregate UDF. See *Note udf-return-values::.

The `xxx_reset()' and `xxx_add()' functions handle their `UDF_ARGS'
argument the same way as functions for non-aggregate UDFs. See *Note
udf-arguments::.

The pointer arguments to `is_null' and `error' are the same for all
calls to `xxx_reset()', `xxx_clear()', `xxx_add()' and `xxx()'. You can
use this to remember that you got an error or whether the `xxx()'
function should return `NULL'. You should not store a string into
`*error'!  `error' points to a single-byte variable, not to a string
buffer.

`*is_null' is reset for each group (before calling `xxx_clear()').
`*error' is never reset.

If `*is_null' or `*error' are set when `xxx()' returns, MySQL returns
`NULL' as the result for the group function.


File: manual.info,  Node: udf-arguments,  Next: udf-return-values,  Prev: udf-aggr-calling,  Up: adding-udf

31.3.2.3 UDF Argument Processing
................................

The `args' parameter points to a `UDF_ARGS' structure that has the
members listed here:

   * `unsigned int arg_count'

     The number of arguments. Check this value in the initialization
     function if you require your function to be called with a
     particular number of arguments. For example:

          if (args->arg_count != 2)
          {
              strcpy(message,"XXX() requires two arguments");
              return 1;
          }

     For other `UDF_ARGS' member values that are arrays, array
     references are zero-based. That is, refer to array members using
     index values from 0 to `args->arg_count' - 1.

   * `enum Item_result *arg_type'

     A pointer to an array containing the types for each argument. The
     possible type values are `STRING_RESULT', `INT_RESULT',
     `REAL_RESULT', and `DECIMAL_RESULT'.

     To make sure that arguments are of a given type and return an
     error if they are not, check the `arg_type' array in the
     initialization function. For example:

          if (args->arg_type[0] != STRING_RESULT ||
              args->arg_type[1] != INT_RESULT)
          {
              strcpy(message,"XXX() requires a string and an integer");
              return 1;
          }

     Arguments of type `DECIMAL_RESULT' are passed as strings, so you
     should handle them the same way as `STRING_RESULT' values.

     As an alternative to requiring your function's arguments to be of
     particular types, you can use the initialization function to set
     the `arg_type' elements to the types you want. This causes MySQL
     to coerce arguments to those types for each call to `xxx()'. For
     example, to specify that the first two arguments should be coerced
     to string and integer, respectively, do this in `xxx_init()':

          args->arg_type[0] = STRING_RESULT;
          args->arg_type[1] = INT_RESULT;

     Exact-value decimal arguments such as `1.3' or `DECIMAL' column
     values are passed with a type of `DECIMAL_RESULT'. However, the
     values are passed as strings. If you want to receive a number, use
     the initialization function to specify that the argument should be
     coerced to a `REAL_RESULT' value:

          args->arg_type[2] = REAL_RESULT;

   * `char **args'

     `args->args' communicates information to the initialization
     function about the general nature of the arguments passed to your
     function. For a constant argument `i', `args->args[i]' points to
     the argument value. (See below for instructions on how to access
     the value properly.) For a non-constant argument, `args->args[i]'
     is `0'. A constant argument is an expression that uses only
     constants, such as `3' or `4*7-2' or `SIN(3.14)'. A non-constant
     argument is an expression that refers to values that may change
     from row to row, such as column names or functions that are called
     with non-constant arguments.

     For each invocation of the main function, `args->args' contains
     the actual arguments that are passed for the row currently being
     processed.

     If argument `i' represents `NULL', `args->args[i]' is a null
     pointer (0).  If the argument is not `NULL', functions can refer
     to it as follows:

        * An argument of type `STRING_RESULT' is given as a string
          pointer plus a length, to allow handling of binary data or
          data of arbitrary length.  The string contents are available
          as `args->args[i]' and the string length is
          `args->lengths[i]'. Do not assume that the string is
          null-terminated.

        * For an argument of type `INT_RESULT', you must cast
          `args->args[i]' to a `long long' value:

               long long int_val;
               int_val = *((long long*) args->args[i]);

        * For an argument of type `REAL_RESULT', you must cast
          `args->args[i]' to a `double' value:

               double    real_val;
               real_val = *((double*) args->args[i]);

        * For an argument of type `DECIMAL_RESULT', the value is passed
          as a string and should be handled like a `STRING_RESULT'
          value.

        * `ROW_RESULT' arguments are not implemented.

   * `unsigned long *lengths'

     For the initialization function, the `lengths' array indicates the
     maximum string length for each argument. You should not change
     these. For each invocation of the main function, `lengths'
     contains the actual lengths of any string arguments that are
     passed for the row currently being processed. For arguments of
     types `INT_RESULT' or `REAL_RESULT', `lengths' still contains the
     maximum length of the argument (as for the initialization
     function).

   * `char *maybe_null'

     For the initialization function, the `maybe_null' array indicates
     for each argument whether the argument value might be null (0 if
     no, 1 if yes).

   * `char **attributes'

     `args->attributes' communicates information information about the
     names of the UDF arguments. For argument `i', the attribute name
     is available as a string in `args->attributes[i]' and the
     attribute length is `args->attribute_lengths[i]'. Do not assume
     that the string is null-terminated.

     By default, the name of a UDF argument is the text of the
     expression used to specify the argument. For UDFs, an argument may
     also have an optional `[AS] ALIAS_NAME' clause, in which case the
     argument name is ALIAS_NAME. The `attributes' value for each
     argument thus depends on whether an alias was given.

     Suppose that a UDF `my_udf()' is invoked as follows:

          SELECT my_udf(expr1, expr2 AS alias1, expr3 alias2);

     In this case, the `attributes' and `attribute_lengths' arrays will
     have these values:

          args->attributes[0] = "expr1"
          args->attribute_lengths[0] = 5

          args->attributes[1] = "alias1"
          args->attribute_lengths[1] = 6

          args->attributes[2] = "alias2"
          args->attribute_lengths[2] = 6

   * `unsigned long *attribute_lengths'

     The `attribute_lengths' array indicates the length of each
     argument name.


File: manual.info,  Node: udf-return-values,  Next: udf-compiling,  Prev: udf-arguments,  Up: adding-udf

31.3.2.4 UDF Return Values and Error Handling
.............................................

The initialization function should return `0' if no error occurred and
`1' otherwise. If an error occurs, `xxx_init()' should store a
null-terminated error message in the `message' parameter. The message
is returned to the client. The message buffer is `MYSQL_ERRMSG_SIZE'
characters long, but you should try to keep the message to less than 80
characters so that it fits the width of a standard terminal screen.

The return value of the main function `xxx()' is the function value,
for `long long' and `double' functions. A string function should return
a pointer to the result and set `*result' and `*length' to the contents
and length of the return value. For example:

     memcpy(result, "result string", 13);
     *length = 13;

The `result' buffer that is passed to the `xxx()' function is 255 bytes
long. If your result fits in this, you don't have to worry about memory
allocation for results.

If your string function needs to return a string longer than 255 bytes,
you must allocate the space for it with `malloc()' in your `xxx_init()'
function or your `xxx()' function and free it in your `xxx_deinit()'
function. You can store the allocated memory in the `ptr' slot in the
`UDF_INIT' structure for reuse by future `xxx()' calls. See *Note
udf-calling::.

To indicate a return value of `NULL' in the main function, set
`*is_null' to `1':

     *is_null = 1;

To indicate an error return in the main function, set `*error' to `1':

     *error = 1;

If `xxx()' sets `*error' to `1' for any row, the function value is
`NULL' for the current row and for any subsequent rows processed by the
statement in which `XXX()' was invoked.  (`xxx()' is not even called
for subsequent rows.)


File: manual.info,  Node: udf-compiling,  Next: udf-security,  Prev: udf-return-values,  Up: adding-udf

31.3.2.5 Compiling and Installing User-Defined Functions
........................................................

Files implementing UDFs must be compiled and installed on the host
where the server runs. This process is described below for the example
UDF file `sql/udf_example.c' that is included in the MySQL source
distribution.

The immediately following instructions are for Unix.  Instructions for
Windows are given later in this section.

The `udf_example.c' file contains the following functions:

   * `metaphon()' returns a metaphon string of the string argument.
     This is something like a soundex string, but it's more tuned for
     English.

   * `myfunc_double()' returns the sum of the ASCII values of the
     characters in its arguments, divided by the sum of the length of
     its arguments.

   * `myfunc_int()' returns the sum of the length of its arguments.

   * `sequence([const int])' returns a sequence starting from the given
     number or 1 if no number has been given.

   * `lookup()' returns the IP number for a hostname.

   * `reverse_lookup()' returns the hostname for an IP number. The
     function may be called either with a single string argument of the
     form `'xxx.xxx.xxx.xxx'' or with four numbers.

A dynamically loadable file should be compiled as a sharable object
file, using a command something like this:

     shell> gcc -shared -o udf_example.so udf_example.c

If you are using `gcc' with `configure' and `libtool' (which is how
MySQL is configured), you should be able to create `udf_example.so'
with a simpler command:

     shell> make udf_example.la

After you compile a shared object containing UDFs, you must install it
and tell MySQL about it. Compiling a shared object from `udf_example.c'
using `gcc' directly produces a file named `udf_example.so'. Compiling
the shared object using `make' produces a file named something like
`udf_example.so.0.0.0' in the `.libs' directory (the exact name may
vary from platform to platform). Copy the shared object to the server's
plugin directory and name it `udf_example.so'. This directory is given
by the value of the `plugin_dir' system variable.

*Note*:

This is a change in MySQL 5.1. For earlier versions of MySQL, the
shared object can be located in any directory that is searched by your
system's dynamic linker.

On some systems, the `ldconfig' program that configures the dynamic
linker does not recognize a shared object unless its name begins with
`lib'. In this case you should rename a file such as `udf_example.so' to
`libudf_example.so'.

On Windows, you can compile user-defined functions by using the
following procedure:

  1. You need to obtain the Bazaar source repository for MySQL 5.1. See
     *Note installing-source-tree::.

  2. You must obtain the CMake build utility from
     `http://www.cmake.org'. (Version 2.4.2 or later is required).

  3. In the source repository, look in the `sql' directory. There are
     files named `udf_example.def' `udf_example.c' there. Copy both
     files from this directory to your working directory.

  4. Create a CMake `makefile' (`CMakeLists.txt') with these contents:

          PROJECT(udf_example)

          # Path for MySQL include directory
          INCLUDE_DIRECTORIES("c:/mysql/include")

          ADD_DEFINITIONS("-DHAVE_DLOPEN")
          ADD_LIBRARY(udf_example MODULE udf_example.c udf_example.def)
          TARGET_LINK_LIBRARIES(udf_example wsock32)

  5. Create the VC project and solution files:

          cmake -G "<Generator>"

     Invoking `cmake --help' shows you a list of valid Generators.

  6. Create `udf_example.dll':

          devenv udf_example.sln /build Release

After the shared object file has been installed, notify `mysqld' about
the new functions with these statements:

     mysql> CREATE FUNCTION metaphon RETURNS STRING SONAME 'udf_example.dll';
     mysql> CREATE FUNCTION myfunc_double RETURNS REAL SONAME 'udf_example.dll';
     mysql> CREATE FUNCTION myfunc_int RETURNS INTEGER SONAME 'udf_example.dll';
     mysql> CREATE FUNCTION sequence RETURNS INTEGER SONAME 'udf_example.dll';
     mysql> CREATE FUNCTION lookup RETURNS STRING SONAME 'udf_example.dll';
     mysql> CREATE FUNCTION reverse_lookup
         ->        RETURNS STRING SONAME 'udf_example.dll';
     mysql> CREATE AGGREGATE FUNCTION avgcost
         ->        RETURNS REAL SONAME 'udf_example.dll';

Functions can be deleted using `DROP FUNCTION':

     mysql> DROP FUNCTION metaphon;
     mysql> DROP FUNCTION myfunc_double;
     mysql> DROP FUNCTION myfunc_int;
     mysql> DROP FUNCTION sequence;
     mysql> DROP FUNCTION lookup;
     mysql> DROP FUNCTION reverse_lookup;
     mysql> DROP FUNCTION avgcost;

The `CREATE FUNCTION' and `DROP FUNCTION' statements update the `func'
system table in the `mysql' database. The function's name, type and
shared library name are saved in the table. You must have the `INSERT'
and `DELETE' privileges for the `mysql' database to create and drop
functions.

You should not use `CREATE FUNCTION' to add a function that has
previously been created. If you need to reinstall a function, you
should remove it with `DROP FUNCTION' and then reinstall it with `CREATE
FUNCTION'. You would need to do this, for example, if you recompile a
new version of your function, so that `mysqld' gets the new version.
Otherwise, the server continues to use the old version.

An active function is one that has been loaded with `CREATE FUNCTION'
and not removed with `DROP FUNCTION'. All active functions are reloaded
each time the server starts, unless you start `mysqld' with the
`--skip-grant-tables' option. In this case, UDF initialization is
skipped and UDFs are unavailable.

If the new function will be referred to in statements that will be
replicated to slave servers, you must ensure that every slave server
also has the function available. Otherwise, replication will fail on
the slaves when they attempt to invoke the function.


File: manual.info,  Node: udf-security,  Prev: udf-compiling,  Up: adding-udf

31.3.2.6 User-Defined Function Security Precautions
...................................................

MySQL takes the following measures to prevent misuse of user-defined
functions.

You must have the `INSERT' privilege to be able to use `CREATE
FUNCTION' and the `DELETE' privilege to be able to use `DROP FUNCTION'.
This is necessary because these statements add and delete rows from the
`mysql.func' table.

UDFs should have at least one symbol defined in addition to the `xxx'
symbol that corresponds to the main `xxx()' function. These auxiliary
symbols correspond to the `xxx_init()', `xxx_deinit()', `xxx_reset()',
`xxx_clear()', and `xxx_add()' functions.  `mysqld' also supports an
`--allow-suspicious-udfs' option that controls whether UDFs that have
only an `xxx' symbol can be loaded. By default, the option is off, to
prevent attempts at loading functions from shared object files other
than those containing legitimate UDFs. If you have older UDFs that
contain only the `xxx' symbol and that cannot be recompiled to include
an auxiliary symbol, it may be necessary to specify the
`--allow-suspicious-udfs' option. Otherwise, you should avoid enabling
this capability.

UDF object files cannot be placed in arbitrary directories.  They must
be located in the server's plugin directory. This directory is given by
the value of the `plugin_dir' system variable.

*Note*:

This is a change in MySQL 5.1. For earlier versions of MySQL, the
shared object can be located in any directory that is searched by your
system's dynamic linker.


File: manual.info,  Node: adding-native-function,  Prev: adding-udf,  Up: adding-functions

31.3.3 Adding a New Native Function
-----------------------------------

To add a new native MySQL function, use the procedure described here,
which requires that you use a source distribution. You cannot add
native functions to a binary distribution because it is necessary to
modify MySQL source code and compile MySQL from the modified source. If
you migrate to another version of MySQL (for example, when a new
version is released), you must repeat the procedure with the new
version.

If the new native function will be referred to in statements that will
be replicated to slave servers, you must ensure that every slave server
also has the function available. Otherwise, replication will fail on
the slaves when they attempt to invoke the function.

To add a new native function, follow these steps to modify source files
in the `sql' directory. For MySQL 5.1, the first two steps apply only
as of 5.1.13. For older versions, see the instructions in the
corresponding section of the MySQL 5.0 manual.

  1. Create a subclass for the function in `item_create.cc':

        * If the function takes a fixed number of arguments, create a
          subclass of `Create_func_arg0', `Create_func_arg1',
          `Create_func_arg2', or `Create_func_arg3', respectively,
          depending on whether the function takes zero, one, two, or
          three arguments. For examples, see the `Create_func_uuid',
          `Create_func_abs', `Create_func_pow', and `Create_func_lpad'
          classes.

        * If the function takes a variable number of arguments, create
          a subclass of `Create_native_func'. For an example, see
          `Create_func_concat'.

  2. To provide a name by which the function can be referred to in SQL
     statements, register the name in `item_create.cc' by adding a line
     to this array:

          static Native_func_registry func_array[]

     You can register several names for the same function. For example,
     see the lines for `"LCASE"' and `"LOWER"', which are aliases for
     `Create_func_lcase'.

  3. In `item_func.h', declare a class inheriting from `Item_num_func'
     or `Item_str_func', depending on whether your function returns a
     number or a string.

  4. In `item_func.cc', add one of the following declarations,
     depending on whether you are defining a numeric or string function:

          double   Item_func_newname::val()
          longlong Item_func_newname::val_int()
          String  *Item_func_newname::Str(String *str)

     If you inherit your object from any of the standard items (like
     `Item_num_func'), you probably only have to define one of these
     functions and let the parent object take care of the other
     functions. For example, the `Item_str_func' class defines a
     `val()' function that executes `atof()' on the value returned by
     `::str()'.

  5. If the function is non-deterministic, include the following
     statement in the item constructor to indicate that function
     results should not be cached:

          current_thd->lex->safe_to_cache_query=0;

     A function is non-deterministic if, given fixed values for its
     arguments, it can return different results for different
     invocations.

  6. You should probably also define the following object function:

          void Item_func_newname::fix_length_and_dec()

     This function should at least calculate `max_length' based on the
     given arguments.  `max_length' is the maximum number of characters
     the function may return. This function should also set `maybe_null
     = 0' if the main function can't return a `NULL' value. The
     function can check whether any of the function arguments can
     return `NULL' by checking the arguments' `maybe_null' variable.
     Look at `Item_func_mod::fix_length_and_dec' for a typical example
     of how to do this.

All functions must be thread-safe. In other words, do not use any
global or static variables in the functions without protecting them
with mutexes.

If you want to return `NULL' from `::val()', `::val_int()', or
`::str()', you should set `null_value' to 1 and return 0.

For `::str()' object functions, there are additional considerations to
be aware of:

   * The `String *str' argument provides a string buffer that may be
     used to hold the result. (For more information about the `String'
     type, take a look at the `sql_string.h' file.)

   * The `::str()' function should return the string that holds the
     result, or `(char*) 0' if the result is `NULL'.

   * All current string functions try to avoid allocating any memory
     unless absolutely necessary!


File: manual.info,  Node: adding-procedures,  Next: porting,  Prev: adding-functions,  Up: extending-mysql

31.4 Adding New Procedures to MySQL
===================================

* Menu:

* procedure-analyse::            `PROCEDURE ANALYSE'
* writing-a-procedure::          Writing a Procedure

In MySQL, you can define a procedure in C++ that can access and modify
the data in a query before it is sent to the client. The modification
can be done on a row-by-row or `GROUP BY' level.

We have created an example procedure to show you what can be done.

Additionally, we recommend that you take a look at `mylua'. With this
you can use the LUA language to load a procedure at runtime into
`mysqld'.


File: manual.info,  Node: procedure-analyse,  Next: writing-a-procedure,  Prev: adding-procedures,  Up: adding-procedures

31.4.1 `PROCEDURE ANALYSE'
--------------------------

`analyse([MAX_ELEMENTS[,MAX_MEMORY]])'

This procedure is defined in the `sql/sql_analyse.cc' file. It examines
the result from a query and returns an analysis of the results that
suggests optimal data types for each column. To obtain this analysis,
append `PROCEDURE ANALYSE' to the end of a `SELECT' statement:

     SELECT ... FROM ... WHERE ... PROCEDURE ANALYSE([MAX_ELEMENTS,[MAX_MEMORY]])

For example:

     SELECT col1, col2 FROM table1 PROCEDURE ANALYSE(10, 2000);

The results show some statistics for the values returned by the query,
and propose an optimal data type for the columns. This can be helpful
for checking your existing tables, or after importing new data. You may
need to try different settings for the arguments so that `PROCEDURE
ANALYSE()' does not suggest the `ENUM' data type when it is not
appropriate.

The arguments are optional and are used as follows:

   * MAX_ELEMENTS (default 256) is the maximum number of distinct
     values that `analyse' notices per column. This is used by
     `analyse' to check whether the optimal data type should be of type
     `ENUM'; if there are more than MAX_ELEMENTS distinct values, then
     `ENUM' is not a suggested type.

   * MAX_MEMORY (default 8192) is the maximum amount of memory that
     `analyse' should allocate per column while trying to find all
     distinct values.


File: manual.info,  Node: writing-a-procedure,  Prev: procedure-analyse,  Up: adding-procedures

31.4.2 Writing a Procedure
--------------------------

For the moment, the only documentation for this is the source.

You can find all information about procedures by examining the
following files:

   * `sql/sql_analyse.cc'

   * `sql/procedure.h'

   * `sql/procedure.cc'

   * `sql/sql_select.cc'


File: manual.info,  Node: porting,  Prev: adding-procedures,  Up: extending-mysql

31.5 Debugging and Porting MySQL
================================

* Menu:

* debugging-server::             Debugging a MySQL Server
* debugging-client::             Debugging a MySQL Client
* the-dbug-package::             The DBUG Package
* rts-threads::                  Comments about RTS Threads
* thread-packages::              Differences Between Thread Packages

This appendix helps you port MySQL to other operating systems. Do check
the list of currently supported operating systems first. See *Note
which-os::. If you have created a new port of MySQL, please let us know
so that we can list it here and on our Web site
(`http://www.mysql.com/'), recommending it to other users.

Note: If you create a new port of MySQL, you are free to copy and
distribute it under the GPL license, but it does not make you a
copyright holder of MySQL.

A working POSIX thread library is needed for the server. On Solaris 2.5
we use Sun PThreads (the native thread support in 2.4 and earlier
versions is not good enough), on Linux we use LinuxThreads by Xavier
Leroy, <Xavier.Leroy@inria.fr>.

The hard part of porting to a new Unix variant without good native
thread support is probably to port MIT-pthreads. See
`mit-pthreads/README' and Programming POSIX Threads
(`http://www.humanfactor.com/pthreads/').

Up to MySQL 4.0.2, the MySQL distribution included a patched version of
Chris Provenzano's Pthreads from MIT (see the MIT Pthreads Web page at
`http://www.mit.edu/afs/sipb/project/pthreads/' and a programming
introduction at `http://www.mit.edu:8001/people/proven/IAP_2000/').
These can be used for some operating systems that do not have POSIX
threads. See *Note mit-pthreads::.

It is also possible to use another user level thread package named FSU
Pthreads (see `http://moss.csc.ncsu.edu/~mueller/pthreads/'). This
implementation is being used for the SCO port.

See the `thr_lock.c' and `thr_alarm.c' programs in the `mysys'
directory for some tests/examples of these problems.

Both the server and the client need a working C++ compiler. We use
`gcc' on many platforms. Other compilers that are known to work are
SPARCworks, Sun Forte, Irix `cc', HP-UX `aCC', IBM AIX `xlC_r'), Intel
`ecc/icc' and Compaq `cxx').

*Important*:

If you are trying to build MySQL 5.1 with `icc' on the IA64 platform,
and need support for MySQL Cluster, you should first ensure that you
are using `icc' version 9.1.043 or later. (For details, see Bug#21875
(http://bugs.mysql.com/21875).)

To compile only the client use `./configure --without-server'.

There is currently no support for only compiling the server, nor is it
likely to be added unless someone has a good reason for it.

If you want/need to change any `Makefile' or the configure script you
also need GNU Automake and Autoconf. See *Note installing-source-tree::.

All steps needed to remake everything from the most basic files.

     /bin/rm */.deps/*.P
     /bin/rm -f config.cache
     aclocal
     autoheader
     aclocal
     automake
     autoconf
     ./configure --with-debug=full --prefix='your installation directory'

     # The makefiles generated above need GNU make 3.75 or newer.
     # (called gmake below)
     gmake clean all install init-db

If you run into problems with a new port, you may have to do some
debugging of MySQL! See *Note debugging-server::.

*Note*:

Before you start debugging `mysqld', first get the test programs
`mysys/thr_alarm' and `mysys/thr_lock' to work. This ensures that your
thread installation has even a remote chance to work!


File: manual.info,  Node: debugging-server,  Next: debugging-client,  Prev: porting,  Up: porting

31.5.1 Debugging a MySQL Server
-------------------------------

* Menu:

* compiling-for-debugging::      Compiling MySQL for Debugging
* making-trace-files::           Creating Trace Files
* making-windows-dumps::         Using `pdb' to create a Windows crashdump
* using-gdb-on-mysqld::          Debugging `mysqld' under `gdb'
* using-stack-trace::            Using a Stack Trace
* using-log-files::              Using Server Logs to Find Causes of Errors in `mysqld'
* reproducible-test-case::       Making a Test Case If You Experience Table Corruption

If you are using some functionality that is very new in MySQL, you can
try to run `mysqld' with the `--skip-new' (which disables all new,
potentially unsafe functionality) or with `--safe-mode' which disables
a lot of optimization that may cause problems. See *Note crashing::.

If `mysqld' doesn't want to start, you should verify that you don't
have any `my.cnf' files that interfere with your setup! You can check
your `my.cnf' arguments with `mysqld --print-defaults' and avoid using
them by starting with `mysqld --no-defaults ...'.

If `mysqld' starts to eat up CPU or memory or if it `hangs,' you can
use `mysqladmin processlist status' to find out if someone is executing
a query that takes a long time. It may be a good idea to run
`mysqladmin -i10 processlist status' in some window if you are
experiencing performance problems or problems when new clients can't
connect.

The command `mysqladmin debug' dumps some information about locks in
use, used memory and query usage to the MySQL log file. This may help
solve some problems. This command also provides some useful information
even if you haven't compiled MySQL for debugging!

If the problem is that some tables are getting slower and slower you
should try to optimize the table with `OPTIMIZE TABLE' or `myisamchk'.
See *Note server-administration::. You should also check the slow
queries with `EXPLAIN'.

You should also read the OS-specific section in this manual for
problems that may be unique to your environment. See *Note
operating-system-specific-notes::.


File: manual.info,  Node: compiling-for-debugging,  Next: making-trace-files,  Prev: debugging-server,  Up: debugging-server

31.5.1.1 Compiling MySQL for Debugging
......................................

If you have some very specific problem, you can always try to debug
MySQL. To do this you must configure MySQL with the `--with-debug' or
the `--with-debug=full' option. You can check whether MySQL was
compiled with debugging by doing: `mysqld --help'. If the `--debug'
flag is listed with the options then you have debugging enabled.
`mysqladmin ver' also lists the `mysqld' version as `mysql ... --debug'
in this case.

If you are using `gcc', the recommended `configure' line is:

     CC=gcc CFLAGS="-O2" CXX=gcc CXXFLAGS="-O2 -felide-constructors \
        -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql \
        --with-debug --with-extra-charsets=complex

This avoids problems with the `libstdc++' library and with C++
exceptions (many compilers have problems with C++ exceptions in
threaded code) and compile a MySQL version with support for all
character sets.

If you suspect a memory overrun error, you can configure MySQL with
`--with-debug=full', which installs a memory allocation (`SAFEMALLOC')
checker.  However, running with `SAFEMALLOC' is quite slow, so if you
get performance problems you should start `mysqld' with the
`--skip-safemalloc' option. This disables the memory overrun checks for
each call to `malloc()' and `free()'.

If `mysqld' stops crashing when you compile it with `--with-debug', you
probably have found a compiler bug or a timing bug within MySQL. In
this case, you can try to add `-g' to the `CFLAGS' and `CXXFLAGS'
variables above and not use `--with-debug'. If `mysqld' dies, you can
at least attach to it with `gdb' or use `gdb' on the core file to find
out what happened.

When you configure MySQL for debugging you automatically enable a lot
of extra safety check functions that monitor the health of `mysqld'. If
they find something `unexpected,' an entry is written to `stderr', which
`mysqld_safe' directs to the error log! This also means that if you are
having some unexpected problems with MySQL and are using a source
distribution, the first thing you should do is to configure MySQL for
debugging! (The second thing is to send mail to a MySQL mailing list
and ask for help. See *Note mailing-lists::. If you believe that you
have found a bug, please use the instructions at *Note bug-reports::.

In the Windows MySQL distribution, `mysqld.exe' is by default compiled
with support for trace files.


File: manual.info,  Node: making-trace-files,  Next: making-windows-dumps,  Prev: compiling-for-debugging,  Up: debugging-server

31.5.1.2 Creating Trace Files
.............................

If the `mysqld' server doesn't start or if you can cause it to crash
quickly, you can try to create a trace file to find the problem.

To do this, you must have a `mysqld' that has been compiled with
debugging support. You can check this by executing `mysqld -V'. If the
version number ends with `-debug', it's compiled with support for trace
files. (On Windows, the debugging server is named `mysqld-debug' rather
than `mysqld' as of MySQL 4.1.)

Start the `mysqld' server with a trace log in `/tmp/mysqld.trace' on
Unix or `C:\mysqld.trace' on Windows:

     shell> mysqld --debug

On Windows, you should also use the `--standalone' flag to not start
`mysqld' as a service. In a console window, use this command:

     C:\> mysqld-debug --debug --standalone

After this, you can use the `mysql.exe' command-line tool in a second
console window to reproduce the problem. You can stop the `mysqld'
server with `mysqladmin shutdown'.

Note that the trace file become *very big*! If you want to generate a
smaller trace file, you can use debugging options something like this:

`mysqld --debug=d,info,error,query,general,where:O,/tmp/mysqld.trace'

This only prints information with the most interesting tags to the
trace file.

If you make a bug report about this, please only send the lines from
the trace file to the appropriate mailing list where something seems to
go wrong! If you can't locate the wrong place, you can ftp the trace
file, together with a full bug report, to
`ftp://ftp.mysql.com/pub/mysql/upload/' so that a MySQL developer can
take a look at it.

The trace file is made with the *DBUG* package by Fred Fish.  See *Note
the-dbug-package::.


File: manual.info,  Node: making-windows-dumps,  Next: using-gdb-on-mysqld,  Prev: making-trace-files,  Up: debugging-server

31.5.1.3 Using `pdb' to create a Windows crashdump
..................................................

Starting with MySQL 5.1.12 the Program Database files (extension `pdb')
are included in the Noinstall distribution of MySQL. These files provide
information for debugging your MySQL installation in the event of a
problem.

The PDB file contains more detailed information about `mysqld' and
other tools that enables more detailed trace and dump files to be
created. You can use these with Dr Watson, `WinDbg' and Visual Studio to
debug `mysqld'.

For more information on PDB files, see Microsoft Knowledge Base Article
121366 (http://support.microsoft.com/kb/121366/). For more information
on the debugging options available, see Debugging Tools for Windows
(http://www.microsoft.com/whdc/devtools/debugging/default.mspx).

Dr Watson is installed with all Windows distributions, but if you have
installed Windows development tools, Dr Watson may have been replaced
with WinDbg, the debugger included with Visual Studio, or the debugging
tools provided with Borland or Delphi.

To generate a crash file using Dr Watson, follow these steps:

  1. Start Dr Watson by running `drwtsn32.exe' interactively using the
     `-i' option:

          C:\> drwtsn32 -i

  2. Set the `Log File Path' to the directory where you want to store
     trace files.

  3. Make sure `Dump All Thread Contexts' and `Append To Existing Log
     File'.

  4. Uncheck `Dump Sumbol Table', `Visual Notification', `Sound
     Notification' and `Create Crash Dump File'.

  5. Set the `Number of Instructions' to a suitable value to capture
     enough calls in the stacktrace.  A value of at 25 should be enough.

Note that the file generated can be very large.


File: manual.info,  Node: using-gdb-on-mysqld,  Next: using-stack-trace,  Prev: making-windows-dumps,  Up: debugging-server

31.5.1.4 Debugging `mysqld' under `gdb'
.......................................

On most systems you can also start `mysqld' from `gdb' to get more
information if `mysqld' crashes.

With some older `gdb' versions on Linux you must use `run --one-thread'
if you want to be able to debug `mysqld' threads. In this case, you can
only have one thread active at a time. We recommend you to upgrade to
gdb 5.1 ASAP as thread debugging works much better with this version!

NPTL threads (the new thread library on Linux) may cause problems while
running `mysqld' under `gdb'. Some symptoms are:

   * `mysqld' hangs during startup (before it writes `ready for
     connections').

   * `mysqld' crashes during a `pthread_mutex_lock()' or
     `pthread_mutex_unlock()' call.

In this case, you should set the following environment variable in the
shell before starting `gdb':

     LD_ASSUME_KERNEL=2.4.1
     export LD_ASSUME_KERNEL

When running `mysqld' under `gdb', you should disable the stack trace
with `--skip-stack-trace' to be able to catch segfaults within `gdb'.

In MySQL 4.0.14 and above you should use the `--gdb' option to `mysqld'.
This installs an interrupt handler for `SIGINT' (needed to stop
`mysqld' with `^C' to set breakpoints) and disable stack tracing and
core file handling.

It's very hard to debug MySQL under `gdb' if you do a lot of new
connections the whole time as `gdb' doesn't free the memory for old
threads. You can avoid this problem by starting `mysqld' with
`thread_cache_size' set to a value equal to `max_connections' + 1. In
most cases just using `--thread_cache_size=5'' helps a lot!

If you want to get a core dump on Linux if `mysqld' dies with a SIGSEGV
signal, you can start `mysqld' with the `--core-file' option. This core
file can be used to make a backtrace that may help you find out why
`mysqld' died:

     shell> gdb mysqld core
     gdb>   backtrace full
     gdb>   quit

See *Note crashing::.

If you are using `gdb' 4.17.x or above on Linux, you should install a
`.gdb' file, with the following information, in your current directory:

     set print sevenbit off
     handle SIGUSR1 nostop noprint
     handle SIGUSR2 nostop noprint
     handle SIGWAITING nostop noprint
     handle SIGLWP nostop noprint
     handle SIGPIPE nostop
     handle SIGALRM nostop
     handle SIGHUP nostop
     handle SIGTERM nostop noprint

If you have problems debugging threads with `gdb', you should download
gdb 5.x and try this instead. The new `gdb' version has very improved
thread handling!

Here is an example how to debug mysqld:

     shell> gdb /usr/local/libexec/mysqld
     gdb> run
     ...
     backtrace full # Do this when mysqld crashes

Include the above output in a bug report, which you can file using the
instructions in *Note bug-reports::.

If `mysqld' hangs you can try to use some system tools like `strace' or
`/usr/proc/bin/pstack' to examine where `mysqld' has hung.

     strace /tmp/log libexec/mysqld

If you are using the Perl `DBI' interface, you can turn on debugging
information by using the `trace' method or by setting the `DBI_TRACE'
environment variable.


File: manual.info,  Node: using-stack-trace,  Next: using-log-files,  Prev: using-gdb-on-mysqld,  Up: debugging-server

31.5.1.5 Using a Stack Trace
............................

On some operating systems, the error log contains a stack trace if
`mysqld' dies unexpectedly. You can use this to find out where (and
maybe why) `mysqld' died. See *Note error-log::. To get a stack trace,
you must not compile `mysqld' with the `-fomit-frame-pointer' option to
gcc. See *Note compiling-for-debugging::.

If the error file contains something like the following:

     mysqld got signal 11;
     The manual section 'Debugging a MySQL server' tells you how to
     use a stack trace and/or the core file to produce a readable
     backtrace that may help in finding out why mysqld died
     Attempting backtrace. You can use the following information
     to find out where mysqld died.  If you see no messages after
     this, something went terribly wrong...
     stack range sanity check, ok, backtrace follows
     0x40077552
     0x81281a0
     0x8128f47
     0x8127be0
     0x8127995
     0x8104947
     0x80ff28f
     0x810131b
     0x80ee4bc
     0x80c3c91
     0x80c6b43
     0x80c1fd9
     0x80c1686

you can find where `mysqld' died by doing the following:

  1. Copy the preceding numbers to a file, for example `mysqld.stack'.

  2. Make a symbol file for the `mysqld' server:

          nm -n libexec/mysqld > /tmp/mysqld.sym

     If you have not linked `mysqld' statically, use the following
     command:

          nm -D -n libexec/mysqld > /tmp/mysqld.sym

     If you want to decode C++ symbols, use the `--demangle', if
     available, to `nm'. If your version of `nm' does not have this
     option, you will need to use the `c++filt' command after the stack
     dump has been produced to demangle the C++ names.

     Note that most MySQL binary distributions (except for the "debug"
     packages, where this information is included inside of the
     binaries themselves) ship with the above file, named
     `mysqld.sym.gz'. In this case, you can simply unpack it by doing:

          gunzip < bin/mysqld.sym.gz > /tmp/mysqld.sym

  3. Execute the following line:

          resolve_stack_dump -s /tmp/mysqld.sym -n mysqld.stack

     If you were not able to include demangled C++ names in your symbol
     file, use `c++filt' on the output:

          resolve_stack_dump -s /tmp/mysqld.sym -n mysqld.stack|c++filt

     This prints out where `mysqld' died. If this doesn't help you find
     out why `mysqld' died, you should make a bug report and include
     the output from the above command with the bug report.

     Note however that in most cases it does not help us to just have a
     stack trace to find the reason for the problem. To be able to
     locate the bug or provide a workaround, we would in most cases
     need to know the query that killed `mysqld' and preferable a test
     case so that we can repeat the problem! See *Note bug-reports::.


File: manual.info,  Node: using-log-files,  Next: reproducible-test-case,  Prev: using-stack-trace,  Up: debugging-server

31.5.1.6 Using Server Logs to Find Causes of Errors in `mysqld'
...............................................................

Note that before starting `mysqld' with `--log' you should check all
your tables with `myisamchk'. See *Note server-administration::.

If `mysqld' dies or hangs, you should start `mysqld' with `--log'. When
`mysqld' dies again, you can examine the end of the log file for the
query that killed `mysqld'.

If you are using `--log' without a file name, the log is stored in the
database directory as `HOST_NAME.log' In most cases it is the last
query in the log file that killed `mysqld', but if possible you should
verify this by restarting `mysqld' and executing the found query from
the `mysql' command-line tools. If this works, you should also test all
complicated queries that didn't complete.

You can also try the command `EXPLAIN' on all `SELECT' statements that
takes a long time to ensure that `mysqld' is using indexes properly.
See *Note explain::.

You can find the queries that take a long time to execute by starting
`mysqld' with `--log-slow-queries'. See *Note slow-query-log::.

If you find the text `mysqld restarted' in the error log file (normally
named `hostname.err') you probably have found a query that causes
`mysqld' to fail. If this happens, you should check all your tables with
`myisamchk' (see *Note server-administration::), and test the queries
in the MySQL log files to see whether one fails. If you find such a
query, try first upgrading to the newest MySQL version.  If this
doesn't help and you can't find anything in the `mysql' mail archive,
you should report the bug to a MySQL mailing list. The mailing lists
are described at `http://lists.mysql.com/', which also has links to
online list archives.

If you have started `mysqld' with `--myisam-recover', MySQL
automatically checks and tries to repair `MyISAM' tables if they are
marked as 'not closed properly' or 'crashed'. If this happens, MySQL
writes an entry in the `hostname.err' file `'Warning: Checking table
...'' which is followed by `Warning: Repairing table' if the table needs
to be repaired. If you get a lot of these errors, without `mysqld'
having died unexpectedly just before, then something is wrong and needs
to be investigated further. See *Note server-options::.

It is not a good sign if `mysqld' did die unexpectedly, but in this
case, you should not investigate the `Checking table...' messages, but
instead try to find out why `mysqld' died.


File: manual.info,  Node: reproducible-test-case,  Prev: using-log-files,  Up: debugging-server

31.5.1.7 Making a Test Case If You Experience Table Corruption
..............................................................

If you get corrupted tables or if `mysqld' always fails after some
update commands, you can test whether this bug is reproducible by doing
the following:

   * Take down the MySQL daemon (with `mysqladmin shutdown').

   * Make a backup of the tables (to guard against the very unlikely
     case that the repair does something bad).

   * Check all tables with `myisamchk -s database/*.MYI'. Repair any
     wrong tables with `myisamchk -r database/TABLE.MYI'.

   * Make a second backup of the tables.

   * Remove (or move away) any old log files from the MySQL data
     directory if you need more space.

   * Start `mysqld' with `--log-bin'. See *Note binary-log::. If you
     want to find a query that crashes `mysqld', you should use `--log
     --log-bin'.

   * When you have gotten a crashed table, stop the `mysqld server'.

   * Restore the backup.

   * Restart the `mysqld' server *without* `--log-bin'

   * Re-execute the commands with `mysqlbinlog binary-log-file |
     mysql'. The binary log is saved in the MySQL database directory
     with the name `hostname-bin.#'.

   * If the tables are corrupted again or you can get `mysqld' to die
     with the above command, you have found reproducible bug that
     should be easy to fix! FTP the tables and the binary log to
     `ftp://ftp.mysql.com/pub/mysql/upload/' and report it in our bugs
     database using the instructions given in *Note bug-reports::.
     (Please note that the `/pub/mysql/upload/' FTP directory is not
     listable, so you'll not see what you've uploaded in your FTP
     client.) If you are a support customer, you can use the MySQL
     Customer Support Center `https://support.mysql.com/' to alert the
     MySQL team about the problem and have it fixed as soon as possible.

You can also use the script `mysql_find_rows' to just execute some of
the update statements if you want to narrow down the problem.


File: manual.info,  Node: debugging-client,  Next: the-dbug-package,  Prev: debugging-server,  Up: porting

31.5.2 Debugging a MySQL Client
-------------------------------

To be able to debug a MySQL client with the integrated debug package,
you should configure MySQL with `--with-debug' or `--with-debug=full'.
See *Note configure-options::.

Before running a client, you should set the `MYSQL_DEBUG' environment
variable:

     shell> MYSQL_DEBUG=d:t:O,/tmp/client.trace
     shell> export MYSQL_DEBUG

This causes clients to generate a trace file in `/tmp/client.trace'.

If you have problems with your own client code, you should attempt to
connect to the server and run your query using a client that is known
to work. Do this by running `mysql' in debugging mode (assuming that you
have compiled MySQL with debugging on):

     shell> mysql --debug=d:t:O,/tmp/client.trace

This provides useful information in case you mail a bug report.  See
*Note bug-reports::.

If your client crashes at some 'legal' looking code, you should check
that your `mysql.h' include file matches your MySQL library file. A
very common mistake is to use an old `mysql.h' file from an old MySQL
installation with new MySQL library.


File: manual.info,  Node: the-dbug-package,  Next: rts-threads,  Prev: debugging-client,  Up: porting

31.5.3 The DBUG Package
-----------------------

The MySQL server and most MySQL clients are compiled with the DBUG
package originally created by Fred Fish. When you have configured MySQL
for debugging, this package makes it possible to get a trace file of
what the program is debugging. See *Note making-trace-files::.

This section summaries the argument values that you can specify in
debug options on the command line for MySQL programs that have been
built with debugging support. For more information about programming
with the DBUG package, see the DBUG manual in the `dbug' directory of
MySQL source distributions. It's best to use a recent distribution to
get the most updated DBUG manual.

You use the debug package by invoking a program with the
`--debug="..."' or the `-#...' option.

Most MySQL programs have a default debug string that is used if you
don't specify an option to `--debug'. The default trace file is usually
`/tmp/program_name.trace' on Unix and `\program_name.trace' on Windows.

The debug control string is a sequence of colon-separated fields as
follows:

     <field_1>:<field_2>:...:<field_N>

Each field consists of a mandatory flag character followed by an
optional ``,'' and comma-separated list of modifiers:

     flag[,modifier,modifier,...,modifier]

The currently recognized flag characters are:

*Flag**Description*
`d'  Enable output from DBUG_<N> macros for the current state. May be
     followed by a list of keywords which selects output only for the
     DBUG macros with that keyword. An empty list of keywords implies
     output for all macros.
`D'  Delay after each debugger output line. The argument is the number of
     tenths of seconds to delay, subject to machine capabilities. For
     example, `-#D,20' specifies a delay of two seconds.
`f'  Limit debugging, tracing, and profiling to the list of named
     functions.  Note that a null list disables all functions. The
     appropriate `d' or `t' flags must still be given; this flag only
     limits their actions if they are enabled.
`F'  Identify the source file name for each line of debug or trace
     output.
`i'  Identify the process with the PID or thread ID for each line of
     debug or trace output.
`g'  Enable profiling. Create a file called `dbugmon.out' containing
     information that can be used to profile the program. May be
     followed by a list of keywords that select profiling only for the
     functions in that list. A null list implies that all functions are
     considered.
`L'  Identify the source file line number for each line of debug or trace
     output.
`n'  Print the current function nesting depth for each line of debug or
     trace output.
`N'  Number each line of debug output.
`o'  Redirect the debugger output stream to the specified file. The
     default output is `stderr'.
`O'  Like `o', but the file is really flushed between each write. When
     needed, the file is closed and reopened between each write.
`p'  Limit debugger actions to specified processes. A process must be
     identified with the `DBUG_PROCESS' macro and match one in the list
     for debugger actions to occur.
`P'  Print the current process name for each line of debug or trace
     output.
`r'  When pushing a new state, do not inherit the previous state's
     function nesting level. Useful when the output is to start at the
     left margin.
`S'  Do function `_sanity(_file_,_line_)' at each debugged function
     until `_sanity()' returns something that differs from 0. (Mostly
     used with `safemalloc' to find memory leaks)
`t'  Enable function call/exit trace lines. May be followed by a list
     (containing only one modifier) giving a numeric maximum trace
     level, beyond which no output occurs for either debugging or
     tracing macros. The default is a compile time option.

Some examples of debug control strings that might appear on a shell
command line (the `-#' is typically used to introduce a control string
to an application program) are:

     -#d:t
     -#d:f,main,subr1:F:L:t,20
     -#d,input,output,files:n
     -#d:t:i:O,\\mysqld.trace

In MySQL, common tags to print (with the `d' option) are `enter',
`exit', `error', `warning', `info', and `loop'.


File: manual.info,  Node: rts-threads,  Next: thread-packages,  Prev: the-dbug-package,  Up: porting

31.5.4 Comments about RTS Threads
---------------------------------

I have tried to use the RTS thread packages with MySQL but stumbled on
the following problems:

They use old versions of many POSIX calls and it is very tedious to
make wrappers for all functions. I am inclined to think that it would
be easier to change the thread libraries to the newest POSIX
specification.

Some wrappers are currently written. See `mysys/my_pthread.c' for more
info.

At least the following should be changed:

`pthread_get_specific' should use one argument.  `sigwait' should take
two arguments. A lot of functions (at least `pthread_cond_wait',
`pthread_cond_timedwait()') should return the error code on error. Now
they return -1 and set `errno'.

Another problem is that user-level threads use the `ALRM' signal and
this aborts a lot of functions (`read', `write', `open'...). MySQL
should do a retry on interrupt on all of these but it is not that easy
to verify it.

The biggest unsolved problem is the following:

To get thread-level alarms I changed `mysys/thr_alarm.c' to wait
between alarms with `pthread_cond_timedwait()', but this aborts with
error `EINTR'. I tried to debug the thread library as to why this
happens, but couldn't find any easy solution.

If someone wants to try MySQL with RTS threads I suggest the following:

   * Change functions MySQL uses from the thread library to POSIX. This
     shouldn't take that long.

   * Compile all libraries with the `-DHAVE_rts_threads'.

   * Compile `thr_alarm'.

   * If there are some small differences in the implementation, they
     may be fixed by changing `my_pthread.h' and `my_pthread.c'.

   * Run `thr_alarm'. If it runs without any `warning,' `error,' or
     aborted messages, you are on the right track. Here is a successful
     run on Solaris:

          Main thread: 1
          Thread 0 (5) started
          Thread: 5  Waiting
          process_alarm
          Thread 1 (6) started
          Thread: 6  Waiting
          process_alarm
          process_alarm
          thread_alarm
          Thread: 6  Slept for 1 (1) sec
          Thread: 6  Waiting
          process_alarm
          process_alarm
          thread_alarm
          Thread: 6  Slept for 2 (2) sec
          Thread: 6  Simulation of no alarm needed
          Thread: 6  Slept for 0 (3) sec
          Thread: 6  Waiting
          process_alarm
          process_alarm
          thread_alarm
          Thread: 6  Slept for 4 (4) sec
          Thread: 6  Waiting
          process_alarm
          thread_alarm
          Thread: 5  Slept for 10 (10) sec
          Thread: 5  Waiting
          process_alarm
          process_alarm
          thread_alarm
          Thread: 6  Slept for 5 (5) sec
          Thread: 6  Waiting
          process_alarm
          process_alarm

          ...
          thread_alarm
          Thread: 5  Slept for 0 (1) sec
          end


File: manual.info,  Node: thread-packages,  Prev: rts-threads,  Up: porting

31.5.5 Differences Between Thread Packages
------------------------------------------

MySQL is very dependent on the thread package used. So when choosing a
good platform for MySQL, the thread package is very important.

There are at least three types of thread packages:

   * User threads in a single process. Thread switching is managed with
     alarms and the threads library manages all non-thread-safe
     functions with locks. Read, write and select operations are
     usually managed with a thread-specific select that switches to
     another thread if the running threads have to wait for data. If
     the user thread packages are integrated in the standard libs
     (FreeBSD and BSDI threads) the thread package requires less
     overhead than thread packages that have to map all unsafe calls
     (MIT-pthreads, FSU Pthreads and RTS threads). In some environments
     (for example, SCO), all system calls are thread-safe so the
     mapping can be done very easily (FSU Pthreads on SCO). Downside:
     All mapped calls take a little time and it's quite tricky to be
     able to handle all situations. There are usually also some system
     calls that are not handled by the thread package (like
     MIT-pthreads and sockets). Thread scheduling isn't always optimal.

   * User threads in separate processes. Thread switching is done by
     the kernel and all data are shared between threads. The thread
     package manages the standard thread calls to allow sharing data
     between threads. LinuxThreads is using this method. Downside: Lots
     of processes. Thread creating is slow. If one thread dies the rest
     are usually left hanging and you must kill them all before
     restarting. Thread switching is somewhat expensive.

   * Kernel threads. Thread switching is handled by the thread library
     or the kernel and is very fast. Everything is done in one process,
     but on some systems, `ps' may show the different threads. If one
     thread aborts, the whole process aborts. Most system calls are
     thread-safe and should require very little overhead. Solaris,
     HP-UX, AIX and OSF/1 have kernel threads.

In some systems kernel threads are managed by integrating user level
threads in the system libraries. In such cases, the thread switching
can only be done by the thread library and the kernel isn't really
`thread aware.'


File: manual.info,  Node: faqs,  Next: error-handling,  Prev: extending-mysql,  Up: Top

Appendix A MySQL 5.1 Frequently Asked Questions
***********************************************

* Menu:

* faqs-general::                 MySQL 5.1 FAQ --- General
* faqs-storage-engines::         MySQL 5.1 FAQ --- Storage Engines
* faqs-sql-modes::               MySQL 5.1 FAQ --- Server SQL Mode
* faqs-stored-procs::            MySQL 5.1 FAQ --- Stored Procedures
* faqs-triggers::                MySQL 5.1 FAQ --- Triggers
* faqs-views::                   MySQL 5.1 FAQ --- Views
* faqs-information-schema::      MySQL 5.0 FAQ --- `INFORMATION_SCHEMA'
* faqs-migration::               MySQL 5.1 FAQ --- Migration
* faqs-security::                MySQL 5.1 FAQ --- Security
* faqs-mysql-cluster::           MySQL 5.1 FAQ --- MySQL Cluster
* faqs-cjk::                     MySQL 5.1 FAQ --- MySQL Chinese, Japanese, and Korean Character Sets
* faqs-connectors-apis::         MySQL 5.1 FAQ --- Connectors & APIs
* faqs-replication::             MySQL 5.1 FAQ --- Replication
* faqs-mysql-drbd-heartbeat::    MySQL 5.1 FAQ --- MySQL, DRBD, and Heartbeat


File: manual.info,  Node: faqs-general,  Next: faqs-storage-engines,  Prev: faqs,  Up: faqs

A.1 MySQL 5.1 FAQ -- General
============================

*Questions*
   * 33.1.1: Which version of MySQL is production-ready (GA)?

   * 33.1.2: Can MySQL 5.1 do subqueries?

   * 33.1.3: Can MySQL 5.1 peform multiple-table inserts, updates, and
     deletes?

   * 33.1.4: Does MySQL 5.1 have a Query Cache? Does it work on Server,
     Instance or Database?

   * 33.1.5: Does MySQL 5.1 have Sequences?

   * 33.1.6: Does MySQL 5.1 have a `NOW()' function with fractions of
     seconds?

   * 33.1.7: Does MySQL 5.1 work with multi-core processors?

   * 33.1.8: Is there a hot backup tool for MyISAM like InnoDB Hot
     Backup?

   * 33.1.9: Have there been there any improvements in error reporting
     when foreign keys fail? Does MySQL now report which column and
     reference failed?

   * 33.1.10: Can MySQL 5.1 perform ACID transactions?

*Questions and Answers* *33.1.1: ** Which version of MySQL is
production-ready (GA)?  *

MySQL 5.0 became Generally Available (GA) with MySQL 5.0.15, which was
released for production use on 19 October 2005. We are now working on
MySQL 5.1, which is currently a Release Candidate. Development work on
MySQL 6.0 has started; currently, MySQL 6.0 is in alpha status.

*33.1.2: ** Can MySQL 5.1 do subqueries?  *

Yes. See *Note subqueries::.

*33.1.3: ** Can MySQL 5.1 peform multiple-table inserts, updates, and
deletes?  *

Yes. For the syntax required to perform multiple-table updates, see
*Note update::; for that required to perform multiple-table deletes, see
*Note delete::.

A multiple-table insert can be accomplished using a trigger whose `FOR
EACH ROW' clause contains multiple `INSERT' statements within a `BEGIN
... END' block. See *Note using-triggers::.

*33.1.4: ** Does MySQL 5.1 have a Query Cache? Does it work on Server,
Instance or Database?  *

Yes. The query cache operates on the server level, caching complete
result sets matched with the original query string.  If an exactly
identical query is made (which often happens, particularly in web
applications), no parsing or execution is necessary; the result is sent
directly from the cache.  Various tuning options are available. See
*Note query-cache::.

*33.1.5: ** Does MySQL 5.1 have Sequences?  *

No. However, MySQL has an `AUTO_INCREMENT' system, which in MySQL 5.1
can also handle inserts in a multi-master replication setup. With the
`--auto-increment-increment' and `--auto-increment-offset' startup
options, you can set each server to generate auto-increment values that
don't conflict with other servers. The `--auto-increment-increment'
value should be greater than the number of servers, and each server
should have a unique offset.

*33.1.6: ** Does MySQL 5.1 have a `NOW()' function with fractions of
seconds?  *

No. This is on the MySQL roadmap as a `rolling feature'. This means
that it is not a flagship feature, but will be implemented, development
time permitting. Specific customer demand may change this scheduling.

However, MySQL does parse time strings with a fractional component. See
*Note time::.

*33.1.7: ** Does MySQL 5.1 work with multi-core processors?  *

Yes. MySQL is fully multi-threaded, and will make use of multiple CPUs,
provided that the operating system supports them.

*33.1.8: ** Is there a hot backup tool for MyISAM like InnoDB Hot
Backup?  *

This is currently under development for a future MySQL release.

*33.1.9: ** Have there been there any improvements in error reporting
when foreign keys fail? Does MySQL now report which column and
reference failed?  *

The foreign key support in `InnoDB' has seen improvements in each major
version of MySQL. Foreign key support generic to all storage engines is
scheduled for MySQL 6.x; this should resolve any inadequacies in the
current storage engine specific implementation.

*33.1.10: ** Can MySQL 5.1 perform ACID transactions?  *

Yes. All current MySQL versions support transactions. The `InnoDB'
storage engine offers full ACID transactions with row-level locking,
multi-versioning, non-locking repeatable reads, and all four SQL
standard isolation levels.

The `NDB' storage engine supports the `READ COMMITTED' transaction
isolation level only.


File: manual.info,  Node: faqs-storage-engines,  Next: faqs-sql-modes,  Prev: faqs-general,  Up: faqs

A.2 MySQL 5.1 FAQ -- Storage Engines
====================================

*Questions*
   * 33.2.1: Where can I obtain complete documentation for MySQL storage
     engines and the pluggable storage engine architecture?

   * 33.2.2: Are there any new storage engines in MySQL 5.1?

   * 33.2.3: Have any storage engines been removed in MySQL 5.1?

   * 33.2.4: What are the unique benefits of the `ARCHIVE' storage
     engine?

   * 33.2.5: Do the new features in MySQL 5.1 apply to all storage
     engines?

*Questions and Answers* *33.2.1: ** Where can I obtain complete
documentation for MySQL storage engines and the pluggable storage
engine architecture?  *

See *Note storage-engines::. That chapter contains information about
all MySQL storage engines except for the `NDB' storage engine used for
MySQL Cluster; `NDB' is covered in *Note mysql-cluster::.

MySQL Enterprise

For expert advice about the storage engine(s) most suitable to your
circumstances subscribe to the MySQL Enterprise Monitor. For more
information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

*33.2.2: ** Are there any new storage engines in MySQL 5.1?  *

No. There have been significant improvements in existing storage
engines, in particular for the `NDB' storage engine that forms the basis
for MySQL Cluster.

The Falcon storage engine is available in MySQL 6.0. See MySQL 6.0
Reference Manual (http://dev.mysql.com/doc/refman/6.0/en/index.html).

*33.2.3: ** Have any storage engines been removed in MySQL 5.1?  *

Yes. MySQL 5.1 no longer supports the `BDB' storage engine. Any existing
`BDB' tables should be converted to another storage engine before
upgrading to MySQL 5.1.

*33.2.4: ** What are the unique benefits of the `ARCHIVE' storage
engine?  *

The `ARCHIVE' storage engine is ideally suited for storing large
amounts of data without indexes; it has a very small footprint, and
performs selects using table scans. See *Note archive-storage-engine::,
for details.

*33.2.5: ** Do the new features in MySQL 5.1 apply to all storage
engines?  *

The general new features such as views, stored procedures, triggers,
`INFORMATION_SCHEMA', precision math (`DECIMAL' column type), and the
`BIT' column type, apply to all storage engines. There are also
additions and changes for specific storage engines.


File: manual.info,  Node: faqs-sql-modes,  Next: faqs-stored-procs,  Prev: faqs-storage-engines,  Up: faqs

A.3 MySQL 5.1 FAQ -- Server SQL Mode
====================================

*Questions*
   * 33.3.1: What are server SQL modes?

   * 33.3.2: How many server SQL modes are there?

   * 33.3.3: How do you determine the server SQL mode?

   * 33.3.4: Is the mode dependent on the database or connection?

   * 33.3.5: Can the rules for strict mode be extended?

   * 33.3.6: Does strict mode impact performance?

   * 33.3.7: What is the default server SQL mode when My SQL 5.1 is
     installed?

*Questions and Answers* *33.3.1: ** What are server SQL modes?  *

Server SQL modes define what SQL syntax MySQL should support and what
kind of data validation checks it should perform.  This makes it easier
to use MySQL in different environments and to use MySQL together with
other database servers. The MySQL Server apply these modes individually
to different clients. For more information, see *Note server-sql-mode::.

*33.3.2: ** How many server SQL modes are there?  *

Each mode can be independently switched on and off. See *Note
server-sql-mode::, for a complete list of available modes.

*33.3.3: ** How do you determine the server SQL mode?  *

You can set the default SQL mode (for `mysqld' startup) with the
`--sql-mode' option. Using the statement `SET [SESSION|GLOBAL]
sql_mode='MODES'', you can change the settings from within a
connection, either locally to the connection, or to take effect
globally. You can retrieve the current mode by issuing a `SELECT
@@sql_mode' statement.

*33.3.4: ** Is the mode dependent on the database or connection?  *

A mode is not linked to a particular database. Modes can be set locally
to the session (connection), or globally for the server. you can change
these settings using `SET [SESSION|GLOBAL] sql_mode='MODES''.

*33.3.5: ** Can the rules for strict mode be extended?  *

When we refer to _strict mode_, we mean a mode where at least one of
the modes `TRADITIONAL', `STRICT_TRANS_TABLES', or `STRICT_ALL_TABLES'
is enabled. Options can be combined, so you can add additional
restrictions to a mode. See *Note server-sql-mode::, for more
information.

*33.3.6: ** Does strict mode impact performance?  *

The intensive validation of input data that some settings requires more
time than if the validation is not done. While the performance impact
is not that great, if you do not require such validation (perhaps your
application already handles all of this), then MySQL gives you the
option of leaving strict mode disabled. However -- if you do require it
-- strict mode can provide such validation.

*33.3.7: ** What is the default server SQL mode when My SQL 5.1 is
installed?  *

By default, no special modes are enabled. See *Note server-sql-mode::,
for information about all available modes and MySQL's default behavior.


File: manual.info,  Node: faqs-stored-procs,  Next: faqs-triggers,  Prev: faqs-sql-modes,  Up: faqs

A.4 MySQL 5.1 FAQ -- Stored Procedures
======================================

*Questions*
   * 33.4.1: Does MySQL 5.1 support stored procedures?

   * 33.4.2: Where can I find documentation for MySQL stored procedures
     and stored functions?

   * 33.4.3: Is there a discussion forum for MySQL stored procedures?

   * 33.4.4: Where can I find the ANSI SQL 2003 specification for stored
     procedures?

   * 33.4.5: How do you manage stored routines?

   * 33.4.6: Is there a way to view all stored procedures and stored
     functions in a given database?

   * 33.4.7: Where are stored procedures stored?

   * 33.4.8: Is it possible to group stored procedures or stored
     functions into packages?

   * 33.4.9: Can a stored procedure call another stored procedure?

   * 33.4.10: Can a stored procedure call a trigger?

   * 33.4.11: Can a stored procedure access tables?

   * 33.4.12: Do stored procedures have a statement for raising
     application errors?

   * 33.4.13: Do stored procedures provide exception handling?

   * 33.4.14: Can MySQL 5.1 stored routines return result sets?

   * 33.4.15: Is `WITH RECOMPILE' supported for stored procedures?

   * 33.4.16: Is there a MySQL equivalent to using `mod_plsql' as a
     gateway on Apache to talk directly to a stored procedure in the
     database?

   * 33.4.17: Can I pass an array as input to a stored procedure?

   * 33.4.18: Can I pass a cursor as an `IN' parameter to a stored
     procedure?

   * 33.4.19: Can I return a cursor as an `OUT' parameter from a stored
     procedure?

   * 33.4.20: Can I print out a variable's value within a stored routine
     for debugging purposes?

   * 33.4.21: Can I commit or roll back transactions inside a stored
     procedure?

   * 33.4.22: Do MySQL 5.1 stored procedures and functions work with
     replication?

   * 33.4.23: Are stored procedures and functions created on a master
     server replicated to a slave?

   * 33.4.24: How are actions that take place inside stored procedures
     and functions replicated?

   * 33.4.25: Are there special security requirements for using stored
     procedures and functions together with replication?

   * 33.4.26: What limitations exist for replicating stored procedure
     and function actions?

   * 33.4.27: Do the preceding limitations affect MySQL's ability to do
     point-in-time recovery?

   * 33.4.28: What is being done to correct the aforementioned
     limitations?

*Questions and Answers* *33.4.1: ** Does MySQL 5.1 support stored
procedures?  *

Yes. MySQL 5.1 supports two types of stored routines -- stored
procedures and stored functions.

*33.4.2: ** Where can I find documentation for MySQL stored procedures
and stored functions?  *

See *Note stored-procedures::.

*33.4.3: ** Is there a discussion forum for MySQL stored procedures?  *

Yes. See http://forums.mysql.com/list.php?98
(http://forums.mysql.com/list.php?98).

*33.4.4: ** Where can I find the ANSI SQL 2003 specification for stored
procedures?  *

Unfortunately, the official specifications are not freely available
(ANSI makes them available for purchase). However, there are books --
such as `SQL-99 Complete, Really' by Peter Gulutzan and Trudy Pelzer --
which give a comprehensive overview of the standard, including coverage
of stored procedures.

*33.4.5: ** How do you manage stored routines?  *

It is always good practice to use a clear naming scheme for your stored
routines. You can manage stored procedures with `CREATE
[FUNCTION|PROCEDURE]', `ALTER [FUNCTION|PROCEDURE]', `DROP
[FUNCTION|PROCEDURE]', and `SHOW CREATE [FUNCTION|PROCEDURE]'. You can
obtain information about existing stored procedures using the
`ROUTINES' table in the `INFORMATION_SCHEMA' database (see *Note
routines-table::).

*33.4.6: ** Is there a way to view all stored procedures and stored
functions in a given database?  *

Yes. For a database named DBNAME, use this query on the
`INFORMATION_SCHEMA.ROUTINES' table:

     SELECT ROUTINE_TYPE, ROUTINE_NAME
         FROM INFORMATION_SCHEMA.ROUTINES
         WHERE ROUTINE_SCHEMA='DBNAME';

For more information, see *Note routines-table::.

The body of a stored routine can be viewed using `SHOW CREATE FUNCTION'
(for a stored function) or `SHOW CREATE PROCEDURE' (for a stored
procedure). See *Note show-create-procedure::, for more information.

*33.4.7: ** Where are stored procedures stored?  *

In the `proc' table of the `mysql' system database. However, you should
not access the tables in the system database directly. Instead, use
`SHOW CREATE FUNCTION' to obtain information about stored functions,
and `SHOW CREATE PROCEDURE' to obtain information about stored
procedures. See *Note show-create-procedure::, for more information
about these statements.

You can also query the `ROUTINES' table in the `INFORMATION_SCHEMA'
database -- see *Note routines-table::, for information about this
table.

*33.4.8: ** Is it possible to group stored procedures or stored
functions into packages?  *

No. This is not supported in MySQL 5.1.

*33.4.9: ** Can a stored procedure call another stored procedure?  *

Yes.

*33.4.10: ** Can a stored procedure call a trigger?  *

A stored procedure can execute an SQL statement, such as an `UPDATE',
that causes a trigger to activate.

*33.4.11: ** Can a stored procedure access tables?  *

Yes. A stored procedure can access one or more tables as required.

*33.4.12: ** Do stored procedures have a statement for raising
application errors?  *

Not in MySQL 5.1. We intend to implement the SQL standard `SIGNAL' and
`RESIGNAL' statements in a future MySQL release.

*33.4.13: ** Do stored procedures provide exception handling?  *

MySQL implements `HANDLER' definitions according to the SQL standard.
See *Note declare-handlers::, for details.

*33.4.14: ** Can MySQL 5.1 stored routines return result sets?  *

_Stored procedures_ can, but stored functions cannot. If you perform an
ordinary `SELECT' inside a stored procedure, the result set is returned
directly to the client. You need to use the MySQL 4.1 (or above)
client-server protocol for this to work. This means that -- for
instance -- in PHP, you need to use the `mysqli' extension rather than
the old `mysql' extension.

*33.4.15: ** Is `WITH RECOMPILE' supported for stored procedures?  *

Not in MySQL 5.1.

*33.4.16: ** Is there a MySQL equivalent to using `mod_plsql' as a
gateway on Apache to talk directly to a stored procedure in the
database?  *

There is no equivalent in MySQL 5.1.

*33.4.17: ** Can I pass an array as input to a stored procedure?  *

Not in MySQL 5.1.

*33.4.18: ** Can I pass a cursor as an `IN' parameter to a stored
procedure?  *

In MySQL 5.1, cursors are available inside stored procedures only.

*33.4.19: ** Can I return a cursor as an `OUT' parameter from a stored
procedure?  *

In MySQL 5.1, cursors are available inside stored procedures only.
However, if you do not open a cursor on a `SELECT', the result will be
sent directly to the client. You can also `SELECT INTO' variables. See
*Note select::.

*33.4.20: ** Can I print out a variable's value within a stored routine
for debugging purposes?  *

Yes, you can do this in a _stored procedure_, but not in a stored
function. If you perform an ordinary `SELECT' inside a stored
procedure, the result set is returned directly to the client. You will
need to use the MySQL 4.1 (or above) client-server protocol for this to
work. This means that -- for instance -- in PHP, you need to use the
`mysqli' extension rather than the old `mysql' extension.

*33.4.21: ** Can I commit or roll back transactions inside a stored
procedure?  *

Yes. However, you cannot perform transactional operations within a
stored function.

*33.4.22: ** Do MySQL 5.1 stored procedures and functions work with
replication?  *

Yes, standard actions carried out in stored procedures and functions
are replicated from a master MySQL server to a slave server. There are
a few limitations that are described in detail in *Note
stored-procedure-logging::.

*33.4.23: ** Are stored procedures and functions created on a master
server replicated to a slave?  *

Yes, creation of stored procedures and functions carried out through
normal DDL statements on a master server are replicated to a slave, so
the objects will exist on both servers. `ALTER' and `DROP' statements
for stored procedures and functions are also replicated.

*33.4.24: ** How are actions that take place inside stored procedures
and functions replicated?  *

MySQL records each DML event that occurs in a stored procedure and
replicates those individual actions to a slave server. The actual calls
made to execute stored procedures are not replicated.

Stored functions that change data are logged as function invocations,
not as the DML events that occur inside each function.

*33.4.25: ** Are there special security requirements for using stored
procedures and functions together with replication?  *

Yes. Because a slave server has authority to execute any statement read
from a master's binary log, special security constraints exist for
using stored functions with replication. If replication or binary
logging in general (for the purpose of point-in-time recovery) is
active, then MySQL DBAs have two security options open to them:

  1. Any user wishing to create stored functions must be granted the
     `SUPER' privilege.

  2. Alternatively, a DBA can set the `log_bin_trust_function_creators'
     system variable to 1, which enables anyone with the standard
     `CREATE ROUTINE' privilege to create stored functions.

*33.4.26: ** What limitations exist for replicating stored procedure and
function actions?  *

Non-deterministic (random) or time-based actions embedded in stored
procedures may not replicate properly. By their very nature, randomly
produced results are not predictable and cannot be exactly reproduced,
and therefore, random actions replicated to a slave will not mirror
those performed on a master. Note that declaring stored functions to be
`DETERMINISTIC' or setting the `log_bin_trust_function_creators' system
variable to 0 will not allow random-valued operations to be invoked.

In addition, time-based actions cannot be reproduced on a slave because
the timing of such actions in a stored procedure is not reproducible
through the binary log used for replication. It records only DML events
and does not factor in timing constraints.

Finally, non-transactional tables for which errors occur during large
DML actions (such as bulk inserts) may experience replication issues in
that a master may be partially updated from DML activity, but no
updates are done to the slave because of the errors that occurred. A
workaround is for a function's DML actions to be carried out with the
`IGNORE' keyword so that updates on the master that cause errors are
ignored and updates that do not cause errors are replicated to the
slave.

*33.4.27: ** Do the preceding limitations affect MySQL's ability to do
point-in-time recovery?  *

The same limitations that affect replication do affect point-in-time
recovery.

*33.4.28: ** What is being done to correct the aforementioned
limitations?  *

As of MySQL 5.1.5, you can choose either statement-based replication or
row-based replication. The original replication implementation is based
on statement-based binary logging. Row-based binary logging resolves the
limitations mentioned earlier.

Beginning with MySQL 5.1.8, _mixed_ replication is also available (by
starting the server with `--binlog-format=mixed'). This hybrid, `smart'
form of replication `knows' whether statement-level replication can
safely be used, or row-level replication is required.

For additional information, see *Note replication-formats::.


File: manual.info,  Node: faqs-triggers,  Next: faqs-views,  Prev: faqs-stored-procs,  Up: faqs

A.5 MySQL 5.1 FAQ -- Triggers
=============================

*Questions*
   * 33.5.1: Where can I find the documentation for MySQL 5.1 triggers?

   * 33.5.2: Is there a discussion forum for MySQL Triggers?

   * 33.5.3: Does MySQL 5.1 have statement-level or row-level triggers?

   * 33.5.4: Are there any default triggers?

   * 33.5.5: How are triggers managed in MySQL?

   * 33.5.6: Is there a way to view all triggers in a given database?

   * 33.5.7: Where are triggers stored?

   * 33.5.8: Can a trigger call a stored procedure?

   * 33.5.9: Can triggers access tables?

   * 33.5.10: Can triggers call an external application through a UDF?

   * 33.5.11: Is possible for a trigger to update tables on a remote
     server?

   * 33.5.12: Do triggers work with replication?

   * 33.5.13: How are actions carried out through triggers on a master
     replicated to a slave?

*Questions and Answers* *33.5.1: ** Where can I find the documentation
for MySQL 5.1 triggers?  *

See *Note triggers::.

*33.5.2: ** Is there a discussion forum for MySQL Triggers?  *

Yes. It is available at `http://forums.mysql.com/list.php?99'.

*33.5.3: ** Does MySQL 5.1 have statement-level or row-level triggers?
*

In MySQL 5.1, all triggers are `FOR EACH ROW' -- that is, the trigger
is activated for each row that is inserted, updated, or deleted. MySQL
5.1 does not support triggers using `FOR EACH STATEMENT'.

*33.5.4: ** Are there any default triggers?  *

Not explicitly. MySQL does have specific special behavior for some
`TIMESTAMP' columns, as well as for columns which are defined using
`AUTO_INCREMENT'.

*33.5.5: ** How are triggers managed in MySQL?  *

In MySQL 5.1, triggers can be created using the `CREATE TRIGGER'
statement, and dropped using `DROP TRIGGER'. See *Note
create-trigger::, and *Note drop-trigger::, for more about these
statements.

Information about triggers can be obtained by querying the
`INFORMATION_SCHEMA.TRIGGERS' table. See *Note triggers-table::.

*33.5.6: ** Is there a way to view all triggers in a given database?  *

Yes. You can obtain a listing of all triggers defined on database
`dbname' using a query on the `INFORMATION_SCHEMA.TRIGGERS' table such
as the one shown here:

     SELECT TRIGGER_NAME, EVENT_MANIPULATION, EVENT_OBJECT_TABLE, ACTION_STATEMENT
         FROM INFORMATION_SCHEMA.TRIGGERS
         WHERE TRIGGER_SCHEMA='DBNAME';

For more information about this table, see *Note triggers-table::.

You can also use the `SHOW TRIGGERS' statement, which is specific to
MySQL. See *Note show-triggers::.

*33.5.7: ** Where are triggers stored?  *

Triggers for a table are currently stored in `.TRG' files, with one
such file one per table.

*33.5.8: ** Can a trigger call a stored procedure?  *

Yes.

*33.5.9: ** Can triggers access tables?  *

A trigger can access both old and new data in its own table.  Through a
stored procedure, or a multiple-table update or delete statement, a
trigger can also affect other tables.

*33.5.10: ** Can triggers call an external application through a UDF?  *

No, not at present.

*33.5.11: ** Is possible for a trigger to update tables on a remote
server?  *

Yes. A table on a remote server could be updated using the `FEDERATED'
storage engine. (See *Note federated-storage-engine::).

*33.5.12: ** Do triggers work with replication?  *

Triggers and replication in MySQL 5.1 work in the same way as in most
other database systems: Actions carried out through triggers on a
master are not replicated to a slave server. Instead, triggers that
exist on tables that reside on a MySQL master server need to be created
on the corresponding tables on any MySQL slave servers so that the
triggers activate on the slaves as well as the master.

*33.5.13: ** How are actions carried out through triggers on a master
replicated to a slave?  *

First, the triggers that exist on a master must be re-created on the
slave server. Once this is done, the replication flow works as any
other standard DML statement that participates in replication. For
example, consider a table `EMP' that has an `AFTER' insert trigger,
which exists on a master MySQL server. The same `EMP' table and `AFTER'
insert trigger exist on the slave server as well. The replication flow
would be:

  1. An `INSERT' statement is made to `EMP'.

  2. The `AFTER' trigger on `EMP' activates.

  3. The `INSERT' statement is written to the binary log.

  4. The replication slave picks up the `INSERT' statement to `EMP' and
     executes it.

  5. The `AFTER' trigger on `EMP' that exists on the slave activates.


File: manual.info,  Node: faqs-views,  Next: faqs-information-schema,  Prev: faqs-triggers,  Up: faqs

A.6 MySQL 5.1 FAQ -- Views
==========================

*Questions*
   * 33.6.1: Where can I find documentation covering MySQL Views?

   * 33.6.2: Is there a discussion forum for MySQL Views?

   * 33.6.3: What happens to a view if an underlying table is dropped or
     renamed?

   * 33.6.4: Does MySQL 5.1 have table snapshots?

   * 33.6.5: Does MySQL 5.1 have materialized views?

   * 33.6.6: Can you insert into views that are based on joins?

*Questions and Answers* *33.6.1: ** Where can I find documentation
covering MySQL Views?  *

See *Note views::.

*33.6.2: ** Is there a discussion forum for MySQL Views?  *

Yes. See http://forums.mysql.com/list.php?100
(http://forums.mysql.com/list.php?100)

*33.6.3: ** What happens to a view if an underlying table is dropped or
renamed?  *

After a view has been created, it is possible to drop or alter a table
or view to which the definition refers. To check a view definition for
problems of this kind, use the `CHECK TABLE' statement. (See *Note
check-table::.)

*33.6.4: ** Does MySQL 5.1 have table snapshots?  *

No.

*33.6.5: ** Does MySQL 5.1 have materialized views?  *

No.

*33.6.6: ** Can you insert into views that are based on joins?  *

It is possible, provided that your `INSERT' statement has a column list
that makes it clear there's only one table involved.

You _cannot_ insert into multiple tables with a single insert on a view.


File: manual.info,  Node: faqs-information-schema,  Next: faqs-migration,  Prev: faqs-views,  Up: faqs

A.7 MySQL 5.0 FAQ -- `INFORMATION_SCHEMA'
=========================================

*Questions*
   * 33.7.1: Where can I find documentation for the MySQL
     `INFORMATION_SCHEMA' database?

   * 33.7.2: Is there a discussion forum for `INFORMATION_SCHEMA'?

   * 33.7.3: Where can I find the ANSI SQL 2003 specification for
     `INFORMATION_SCHEMA'?

   * 33.7.4: What is the difference between the Oracle Data Dictionary
     and MySQL's `INFORMATION_SCHEMA'?

   * 33.7.5: Can I add to or otherwise modify the tables found in the
     `INFORMATION_SCHEMA' database?

*Questions and Answers* *33.7.1: ** Where can I find documentation for
the MySQL `INFORMATION_SCHEMA' database?  *

See *Note information-schema::

*33.7.2: ** Is there a discussion forum for `INFORMATION_SCHEMA'?  *

See http://forums.mysql.com/list.php?101
(http://forums.mysql.com/list.php?101).

*33.7.3: ** Where can I find the ANSI SQL 2003 specification for
`INFORMATION_SCHEMA'?  *

Unfortunately, the official specifications are not freely available.
(ANSI makes them available for purchase.)  However, there are books
available -- such as `SQL-99 Complete, Really' by Peter Gulutzan and
Trudy Pelzer -- which give a comprehensive overview of the standard,
including `INFORMATION_SCHEMA'.

*33.7.4: ** What is the difference between the Oracle Data Dictionary
and MySQL's `INFORMATION_SCHEMA'?  *

Both Oracle and MySQL provide metadata in tables. However, Oracle and
MySQL use different table names and column names.  MySQL's
implementation is more similar to those found in DB2 and SQL Server,
which also support `INFORMATION_SCHEMA' as defined in the SQL standard.

*33.7.5: ** Can I add to or otherwise modify the tables found in the
`INFORMATION_SCHEMA' database?  *

No. Since applications may rely on a certain standard structure, this
should not be modified. For this reason, _MySQL AB cannot support bugs
or other issues which result from modifying `INFORMATION_SCHEMA' tables
or data_.


File: manual.info,  Node: faqs-migration,  Next: faqs-security,  Prev: faqs-information-schema,  Up: faqs

A.8 MySQL 5.1 FAQ -- Migration
==============================

*Questions*
   * 33.8.1: Where can I find information on how to migrate from MySQL
     5.0 to MySQL 5.1?

   * 33.8.2: How has storage engine (table type) support changed in
     MySQL 5.1 from previous versions?

*Questions and Answers* *33.8.1: ** Where can I find information on how
to migrate from MySQL 5.0 to MySQL 5.1?  *

For detailed upgrade information, see *Note upgrade::. We recommend
that you do not skip a major version when upgrading, but rather
complete the process in steps, upgrading from one major version to the
next in each step. This may seem more complicated, but it will you save
time and trouble -- if you encounter problems during the upgrade, their
origin will be easier to identify, either by you or -- if you have a
MySQL Network subscription -- by MySQL support.

*33.8.2: ** How has storage engine (table type) support changed in MySQL
5.1 from previous versions?  *

Storage engine support has changed as follows:

   * Support for `ISAM' tables was removed in MySQL 5.0 and you should
     now use the `MyISAM' storage engine in place of `ISAM'. To convert
     a table TBLNAME from `ISAM' to `MyISAM', simply issue a statement
     such as this one:

          ALTER TABLE TBLNAME ENGINE=MYISAM;

   * Internal `RAID' for `MyISAM' tables was also removed in MySQL 5.0.
     This was formerly used to allow large tables in filesystems that
     did not support file sizes greater than 2GB. All modern
     filesystems allow for larger tables; in addition, there are now
     other solutions such as `MERGE' tables and views.

   * The `VARCHAR' column type now retains trailing spaces in all
     storage engines.

   * `MEMORY' tables (formerly known as `HEAP' tables) can also contain
     `VARCHAR' columns.


File: manual.info,  Node: faqs-security,  Next: faqs-mysql-cluster,  Prev: faqs-migration,  Up: faqs

A.9 MySQL 5.1 FAQ -- Security
=============================

*Questions*
   * 33.9.1: Where can I find documentation that addresses security
     issues for MySQL?

   * 33.9.2: Does MySQL 5.1 have native support for SSL?

   * 33.9.3: Is SSL support be built into MySQL binaries, or must I
     recompile the binary myself to enable it?

   * 33.9.4: Does MySQL 5.1 have built-in authentication against LDAP
     directories?

   * 33.9.5: Does MySQL 5.1 include support for Roles Based Access
     Control (RBAC)?

*Questions and Answers* *33.9.1: ** Where can I find documentation that
addresses security issues for MySQL?  *

The best place to start is *Note security::.

Other portions of the MySQL Documentation which you may find useful
with regard to specific security concerns include the following:

   * *Note security-guidelines::.

   * *Note security-against-attack::.

   * *Note resetting-permissions::.

   * *Note changing-mysql-user::.

   * *Note udf-security::.

   * *Note privileges-options::.

   * *Note load-data-local::.

   * *Note post-installation::.

   * *Note selinux::.

   * *Note secure-basics::.

MySQL Enterprise

The MySQL Enterprise Monitor enforces best practices for maximizing the
security of your servers. For more information see
`http://www.mysql.com/products/enterprise/advisors.html'.

*33.9.2: ** Does MySQL 5.1 have native support for SSL?  *

Most 5.1 binaries have support for SSL connections between the client
and server. We can't currently build with the new YaSSL library
everywhere, as it's still quite new and does not compile on all
platforms yet. See *Note secure-connections::.

You can also tunnel a connection via SSH, if (for instance) if the
client application doesn't support SSL connections.  For an example,
see *Note windows-and-ssh::.

*33.9.3: ** Is SSL support be built into MySQL binaries, or must I
recompile the binary myself to enable it?  *

Most 5.1 binaries have SSL enabled for client-server connections that
are secured, authenticated, or both. However, the YaSSL library
currently does not compile on all platforms. See *Note
secure-connections::, for a complete listing of supported and
unsupported platforms.

*33.9.4: ** Does MySQL 5.1 have built-in authentication against LDAP
directories?  *

No. Support for external authentication methods is on the MySQL roadmap
as a `rolling feature', which means that we plan to implement it in the
future, but we have not yet determined when this will be done.

*33.9.5: ** Does MySQL 5.1 include support for Roles Based Access
Control (RBAC)?  *

No. Support for roles is on the MySQL roadmap as a `rolling feature',
which means that we plan to implement it in the future, but we have not
yet determined when this will be done.


File: manual.info,  Node: faqs-mysql-cluster,  Next: faqs-cjk,  Prev: faqs-security,  Up: faqs

A.10 MySQL 5.1 FAQ -- MySQL Cluster
===================================

In the following section, we answer questions that are frequently asked
about MySQL Cluster and the `NDBCLUSTER' storage engine.

*Questions*
   * 33.10.1: 

     Which versions of the MySQL software support Cluster? Do I have to
     compile from source?

   * 33.10.2: 

     What does `NDB' mean?

   * 33.10.3: 

     What is the difference between using MySQL Cluster _vs_ using
     MySQL replication?

   * 33.10.4: 

     Do I need to do any special networking to run MySQL Cluster?  How
     do computers in a cluster communicate?

   * 33.10.5: 

     How many computers do I need to run a MySQL Cluster, and why?

   * 33.10.6: 

     What do the different computers do in a MySQL Cluster?

   * 33.10.7: 

     With which operating systems can I use Cluster?

   * 33.10.8: 

     What are the hardware requirements for running MySQL Cluster?

   * 33.10.9: 

     How much RAM do I need to use MySQL Cluster? Is it possible to use
     disk memory at all?

   * 33.10.10: What filesystems can I use with MySQL Cluster? What about
     network filesystems or network shares?

   * 33.10.11: 

     Can I run MySQL Cluster nodes inside virtual machines (such as
     those created by VirtualBox, VMWare, Parallels, or Xen)?

   * 33.10.12: 

     I am trying to populate a MySQL Cluster database. The loading
     process terminates prematurely and I get an error message like
     this one:

     ``ERROR 1114: The table 'my_cluster_table' is full''

     Why is this happening?

   * 33.10.13: 

     MySQL Cluster uses TCP/IP. Does this mean that I can run it over
     the Internet, with one or more nodes in remote locations?

   * 33.10.14: 

     Do I have to learn a new programming or query language to use
     MySQL Cluster?

   * 33.10.15: 

     How do I find out what an error or warning message means when
     using MySQL Cluster?

   * 33.10.16: 

     Is MySQL Cluster transaction-safe? What isolation levels are
     supported?

   * 33.10.17: What storage engines are supported by MySQL Cluster?

   * 33.10.18: In the event of a catastrophic failure -- say, for
     instance, the whole city loses power _and_ my UPS fails -- would I
     lose all my data?

   * 33.10.19: Is it possible to use `FULLTEXT' indexes with MySQL
     Cluster?

   * 33.10.20: Can I run multiple nodes on a single computer?

   * 33.10.21: Can I add data nodes to a MySQL Cluster without
     restarting it?

   * 33.10.22: Are there any limitations that I should be aware of when
     using MySQL Cluster?

   * 33.10.23: 

     How do I import an existing MySQL database into a MySQL Cluster?

   * 33.10.24: How do cluster nodes communicate with one another?

   * 33.10.25: 

     What is an _arbitrator_?

   * 33.10.26: 

     What data types are supported by MySQL Cluster?

   * 33.10.27: 

     How do I start and stop MySQL Cluster?

   * 33.10.28: What happens to MySQL Cluster data when the cluster is
     shut down?

   * 33.10.29: Is it a good idea to have more than one management node
     for a MySQL Cluster?

   * 33.10.30: Can I mix different kinds of hardware and operating
     systems in one MySQL Cluster?

   * 33.10.31: Can I run two data nodes on a single host? Two SQL nodes?

   * 33.10.32: Can I use hostnames with MySQL Cluster?

   * 33.10.33: How do I handle MySQL users in a MySQL Cluster having
     multiple MySQL servers?

   * 33.10.34: How do I continue to send queries in the event that one
     of the SQL nodes fails?

*Questions and Answers* *33.10.1: ** ** Which versions of the MySQL
software support Cluster? Do I have to compile from source?  *

Beginning with MySQL 5.1.24, MySQL Cluster is no longer supported in
standard MySQL Server 5.1 releases. Instead, MySQL Cluster is now
released as a separate product.  Currently, two MySQL Cluster release
series are available:

   * MySQL Cluster NDB 6.2

     This is the preferred series for production use. The latest MySQL
     Cluster NDB 6.2 sources and binaries can be obtained from
     `http://dev.mysql.com/downloads/cluster'.

   * MySQL Cluster NDB 6.3

     This series can also be used in production; however, you must
     compile the binaries yourself. The latest MySQL Cluster NDB 6.3
     sources can be obtained from the MySQL FTP site at
     `ftp://ftp.mysql.com/pub/mysql/download/cluster_telco/'.

You should use MySQL NDB Cluster NDB 6.2 or 6.3 for new deployments,
and to upgrade to one of these release series if you are using a
previous version of MySQL with clustering support. For an overview of
improvements in MySQL Cluster NDB 6.2 and 6.3, see *Note
mysql-cluster-changes-5-1-ndb-6-2::, and *Note
mysql-cluster-changes-5-1-ndb-6-3::.

You can determine whether your server has `NDB' support using either
either of the statements `SHOW VARIABLES LIKE 'have_%'' or `SHOW
ENGINES'.

*33.10.2: ** ** What does `NDB' mean?  *

This stands for `*N*etwork *D*ata*b*ase'.  `NDB' (also known as
`NDBCLUSTER') is the storage engine that enables clustering in MySQL.

*33.10.3: ** ** What is the difference between using MySQL Cluster _vs_
using MySQL replication?  *

In traditional MySQL replication, a master MySQL server updates one or
more slaves. Transactions are committed sequentially, and a slow
transaction can cause the slave to lag behind the master. This means
that if the master fails, it is possible that the slave might not have
recorded the last few transactions. If a transaction-safe engine such as
`InnoDB' is being used, a transaction will either be complete on the
slave or not applied at all, but replication does not guarantee that
all data on the master and the slave will be consistent at all times.
In MySQL Cluster, all data nodes are kept in synchrony, and a
transaction committed by any one data node is committed for all data
nodes. In the event of a data node failure, all remaining data nodes
remain in a consistent state.

In short, whereas standard MySQL replication is _asynchronous_, MySQL
Cluster is _synchronous_.

We have implemented (asynchronous) replication for MySQL Cluster in
MySQL 5.1 and MySQL Cluster NDB 6.x. This includes the capability to
replicate both between two clusters, and from a MySQL Cluster to a
non-Cluster MySQL server. See *Note mysql-cluster-replication::.

*33.10.4: ** ** Do I need to do any special networking to run MySQL
Cluster?  How do computers in a cluster communicate?  *

MySQL Cluster is intended to be used in a high-bandwidth environment,
with computers connecting via TCP/IP. Its performance depends directly
upon the connection speed between the cluster's computers. The minimum
connectivity requirements for MySQL Cluster include a typical
100-megabit Ethernet network or the equivalent. We recommend you use
gigabit Ethernet whenever available.

The faster SCI protocol is also supported, but requires special
hardware. See *Note mysql-cluster-interconnects::, for more information
about SCI.

*33.10.5: ** ** How many computers do I need to run a MySQL Cluster, and
why?  *

A minimum of three computers is required to run a viable cluster.
However, the minimum *recommended* number of computers in a MySQL
Cluster is four: one each to run the management and SQL nodes, and two
computers to serve as data nodes. The purpose of the two data nodes is
to provide redundancy; the management node must run on a separate
machine to guarantee continued arbitration services in the event that
one of the data nodes fails.

To provide increased throughput and high availability, you should use
multiple SQL nodes (MySQL Servers connected to the cluster). It is also
possible (although not strictly necessary) to run multiple management
servers.

*33.10.6: ** ** What do the different computers do in a MySQL Cluster?
*

A MySQL Cluster has both a physical and logical organization, with
computers being the physical elements.  The logical or functional
elements of a cluster are referred to as _nodes_, and a computer
housing a cluster node is sometimes referred to as a _cluster host_.
There are three types of nodes, each corresponding to a specific role
within the cluster. These are:

   * Management node

     This node provides management services for the cluster as a whole,
     including startup, shutdown, backups, and configuration data for
     the other nodes. The management node server is implemented as the
     application `ndb_mgmd'; the management client used to control
     MySQL Cluster is `ndb_mgm'.

   * Data node

     This type of node stores and replicates data. Data node
     functionality is handled by instances of the `NDB' data node
     process `ndbd'.

   * SQL node

     This is simply an instance of MySQL Server (`mysqld') that is
     built with support for the `NDBCLUSTER' storage engine and started
     with the `--ndb-cluster' option to enable the engine and the
     `--ndb-connectstring' option to enable it to connect to a MySQL
     Cluster management server. For more about these options, see *Note
     mysql-cluster-mysqld-command-options::.

     *Note*:

     An _API node_ is any application that makes direct use of Cluster
     data nodes for data storage and retrieval. An SQL node can thus be
     considered a type of API node that uses a MySQL Server to provide
     an SQL interface to the Cluster. You can write such applications
     (that do not depend on a MySQL Server) using the NDB API, which
     supplies a direct, object-oriented transaction and scanning
     interface to MySQL Cluster data; see The NDB API
     (http://dev.mysql.com/doc/ndbapi/en/overview-ndb-api.html), for
     more information.

*33.10.7: ** ** With which operating systems can I use Cluster?  *

MySQL Cluster is supported on most Unix-like operating systems,
including Linux, Mac OS X, Solaris, and HP-UX.  MySQL Cluster is _not_
supported on Windows at this time. We are working to add MySQL Cluster
support for other platforms, including Windows; eventually we intend to
offer MySQL Cluster on all platforms for which MySQL itself is
supported.

For more detailed information concerning the level of support which is
offered for MySQL Cluster on various operating system versions, OS
distributions, and hardware platforms, please refer to
`http://www.mysql.com/support/supportedplatforms/cluster.html'.

*33.10.8: ** ** What are the hardware requirements for running MySQL
Cluster?  *

MySQL Cluster should run on any platform for which `NDB'-enabled
binaries are available. For data nodes, faster CPUs and more memory are
likely to improve performance, and 64-bit CPUs are likely to be more
effective than 32-bit processors. There must be sufficient memory on
machines used for data nodes to hold each node's share of the database
(see _How much RAM do I Need?_ for more information). Nodes can
communicate via a standard TCP/IP network and hardware. For SCI
support, special networking hardware is required (see *Note
mysql-cluster-interconnects::).

*33.10.9: ** ** How much RAM do I need to use MySQL Cluster? Is it
possible to use disk memory at all?  *

Previous to MySQL 5.1 (including MySQL Cluster NDB 6.2 and 6.3), MySQL
Cluster was in-memory only. This meant that all table data (including
indexes) was stored in RAM. If your data took up 1 GB of space and you
wanted to replicate it once in the cluster, you needed 2 GB of memory
to do so (1 GB per replica). This was in addition to the memory required
by the operating system and any applications running on the cluster
computers. This is still true of in-memory tables.

If a data node's memory usage exceeds what is available in RAM, then
the system will attempt to use swap space up to the limit set for
`DataMemory'. However, this will at best result in severely degraded
performance, and may cause the node to be dropped due to slow response
time (missed heartbeats). We do not recommend on relying on disk
swapping in a production environment for this reason.  In any case,
once the `DataMemory' limit is reached, any operations requiring
additional memory (such as inserts) will fail.

`NDBCLUSTER' in MySQL 5.1 includes support for Disk Data, which helps
to alleviate these issues. See *Note mysql-cluster-disk-data::, for
more information.

You can use the following formula for obtaining a rough estimate of how
much RAM is needed for each data node in the cluster:

     (SizeofDatabase x NumberOfReplicas x 1.1 ) / NumberOfDataNodes

To calculate the memory requirements more exactly requires determining,
for each table in the cluster database, the storage space required per
row (see *Note storage-requirements::, for details), and multiplying
this by the number of rows. You must also remember to account for any
column indexes as follows:

   * Each primary key or hash index created for an `NDBCLUSTER' table
     requires 21-25 bytes per record. These indexes use `IndexMemory'.

   * Each ordered index requires 10 bytes storage per record, using
     `DataMemory'.

   * Creating a primary key or unique index also creates an ordered
     index, unless this index is created with `USING HASH'. In other
     words:

        * A primary key or unique index on a Cluster table normally
          takes up 31 to 35 bytes per record.

        * However, if the primary key or unique index is created with
          `USING HASH', then it requires only 21 to 25 bytes per record.

Note that creating MySQL Cluster tables with `USING HASH' for all
primary keys and unique indexes will generally cause table updates to
run more quickly -- in some cases by a much as 20 to 30 percent faster
than updates on tables where `USING HASH' was not used in creating
primary and unique keys. This is due to the fact that less memory is
required (because no ordered indexes are created), and that less CPU
must be utilized (because fewer indexes must be read and possibly
updated). However, it also means that queries that could otherwise use
range scans must be satisfied by other means, which can result in slower
selects.

When calculating Cluster memory requirements, you may find useful the
`ndb_size.pl' utility which is available in recent MySQL 5.1 releases.
This Perl script connects to a current (non-Cluster) MySQL database and
creates a report on how much space that database would require if it
used the `NDBCLUSTER' storage engine. For more information, see *Note
mysql-cluster-utilities-ndb-size::.

It is especially important to keep in mind that _every MySQL Cluster
table must have a primary key_. The `NDB' storage engine creates a
primary key automatically if none is defined, and this primary key is
created without `USING HASH'.

To determine how much memory is being used for storage of Cluster
indexes at any given time, you can check the Cluster log for the
warnings which are written to it when 80% of available `DataMemory' or
`IndexMemory' is in use, and again when use reaches 85%, 90%, and so
on. Beginning with MySQL Cluster NDB 6.2.3 and 6.3.0, you can use the
`REPORT MemoryUsage' command in the cluster management client to obtain
a real-time report of the amount of memory used to store MySQL Cluster
data and indexes. For more information about this comannd, see

*33.10.10: ** What filesystems can I use with MySQL Cluster? What about
network filesystems or network shares?  *

Generally, any filesystem that is native to the host operating system
should work well with MySQL Cluster. If you find that a given
filesystem works particularly well (or not so especially well) with
MySQL Cluster, we invite you to discuss your findings in the MySQL
Cluster Forums (http://forums.mysql.com/list.php?25).

We do not test MySQL Cluster with `FAT' or `VFAT' filesystems on Linux.
Because of this, and due to the fact that these are not very useful for
any purpose other than sharing disk partitions between Linux and
Windows operating systems on multi-boot computers, we do not recommend
their use with MySQL Cluster.

MySQL Cluster is implemented as a shared-nothing solution; the idea
behind this is that the failure of a single piece of hardware should
not cause the failure of multiple cluster nodes, or possibly even the
failure of the cluster as a whole. For this reason, the use of network
shares or network filesystems is not supported for MySQL Cluster. This
also applies to shared storage devices such as SANs.

*33.10.11: ** ** Can I run MySQL Cluster nodes inside virtual machines
(such as those created by VirtualBox, VMWare, Parallels, or Xen)?  *

This is possible but not recommended for a production environment.

We have found that running MySQL Cluster processes inside a virtual
machine can give rise to issues with timing and disk subsystems that
have a strong negative impact on the operation of the cluster. The
behavior of the cluster is often unpredictable in these cases.

If an issue can be reproduced outside the virtual environment, then we
may be able to provide assistance.  Otherwise, we cannot support it at
this time.

*33.10.12: ** ** ** I am trying to populate a MySQL Cluster database.
The loading process terminates prematurely and I get an error message
like this one: ** ``ERROR 1114: The table 'my_cluster_table' is full''
** Why is this happening?  *

The cause is very likely to be that your setup does not provide
sufficient RAM for all table data and all indexes, _including the
primary key required by the `NDB' storage engine and automatically
created in the event that the table definition does not include the
definition of a primary key_.

It is also worth noting that all data nodes should have the same amount
of RAM, since no data node in a cluster can use more memory than the
least amount available to any individual data node. For example, if
there are four computers hosting Cluster data nodes, and three of these
have 3GB of RAM available to store Cluster data while the remaining
data node has only 1GB RAM, then each data node can devote at most 1GB
to MySQL Cluster data and indexes.

*33.10.13: ** ** MySQL Cluster uses TCP/IP. Does this mean that I can
run it over the Internet, with one or more nodes in remote locations?  *

It is _very_ unlikely that a cluster would perform reliably under such
conditions, as MySQL Cluster was designed and implemented with the
assumption that it would be run under conditions guaranteeing dedicated
high-speed connectivity such as that found in a LAN setting using 100
Mbps or gigabit Ethernet -- preferably the latter. We neither test nor
warrant its performance using anything slower than this.

Also, it is extremely important to keep in mind that communications
between the nodes in a MySQL Cluster are not secure; they are neither
encrypted nor safeguarded by any other protective mechanism. The most
secure configuration for a cluster is in a private network behind a
firewall, with no direct access to any Cluster data or management nodes
from outside. (For SQL nodes, you should take the same precautions as
you would with any other instance of the MySQL server.) For more
information, see *Note mysql-cluster-security::.

*33.10.14: ** ** Do I have to learn a new programming or query language
to use MySQL Cluster?  *

No. Although some specialized commands are used to manage and configure
the cluster itself, only standard (My)SQL queries and commands are
required for the following operations:

   * Creating, altering, and dropping tables (including Disk Data
     tables and related objects)

   * Inserting, updating, and deleting table data

   * Creating, changing, and dropping primary and unique indexes

Some specialized configuration parameters and files are required to set
up a MySQL Cluster -- see *Note mysql-cluster-config-file::, for
information about these.

A few simple commands are used in the MySQL Cluster management client
(`ndb_mgm') for tasks such as starting and stopping cluster nodes. See
*Note mysql-cluster-mgm-client-commands::.

*33.10.15: ** ** How do I find out what an error or warning message
means when using MySQL Cluster?  *

There are two ways in which this can be done:

   * From within the `mysql' client, use `SHOW ERRORS' or `SHOW
     WARNINGS' immediately upon being notified of the error or warning
     condition. Errors and warnings also be displayed in MySQL Query
     Browser.

   * From a system shell prompt, use `perror --ndb ERROR_CODE'.

*33.10.16: ** ** Is MySQL Cluster transaction-safe? What isolation
levels are supported?  *

_Yes_: For tables created with the `NDB' storage engine, transactions
are supported. Currently, MySQL Cluster supports only the `READ
COMMITTED' transaction isolation level.

*33.10.17: ** What storage engines are supported by MySQL Cluster?  *

Clustering with MySQL is supported only by the `NDB' storage engine.
That is, in order for a table to be shared between nodes in a MySQL
Cluster, the table must be created using `ENGINE=NDB' (or the
equivalent option `ENGINE=NDBCLUSTER').

It is possible to create tables using other storage engines (such as
`MyISAM' or `InnoDB') on a MySQL server being used with a MySQL
Cluster, but these non-`NDB' tables do _not_ participate in clustering;
they are strictly local to the individual MySQL server instance on
which they are created.

*33.10.18: ** In the event of a catastrophic failure -- say, for
instance, the whole city loses power _and_ my UPS fails -- would I lose
all my data?  *

All committed transactions are logged. Therefore, although it is
possible that some data could be lost in the event of a catastrophe,
this should be quite limited. Data loss can be further reduced by
minimizing the number of operations per transaction. (It is not a good
idea to perform large numbers of operations per transaction in any
case.)

*33.10.19: ** Is it possible to use `FULLTEXT' indexes with MySQL
Cluster?  *

`FULLTEXT' indexing is not supported by any storage engine other than
`MyISAM'. We are working to add this capability to MySQL Cluster tables
in a future release.

*33.10.20: ** Can I run multiple nodes on a single computer?  *

It is possible but not advisable. One of the chief reasons to run a
cluster is to provide redundancy. To obtain the full benefits of this
redundancy, each node should reside on a separate machine. If you place
multiple nodes on a single machine and that machine fails, you lose all
of those nodes.  Given that MySQL Cluster can be run on commodity
hardware loaded with a low-cost (or even no-cost) operating system, the
expense of an extra machine or two is well worth it to safeguard
mission-critical data. It also worth noting that the requirements for a
cluster host running a management node are minimal. This task can be
accomplished with a 200 MHz Pentium CPU and sufficient RAM for the
operating system plus a small amount of overhead for the `ndb_mgmd' and
`ndb_mgm' processes.

It is acceptable to run multiple cluster data nodes on a single host
for learning about MySQL Cluster, or for testing purposes; however,
this is not generally supported for production use.

*33.10.21: ** Can I add data nodes to a MySQL Cluster without restarting
it?  *

Not at present. A rolling restart is all that is required for adding
new management or SQL nodes to a MySQL Cluster (see *Note
mysql-cluster-rolling-restart::).  Adding data nodes is more complex,
and requires the following steps:

  1. Make a complete backup of all Cluster data.

  2. Completely shut down the cluster and all cluster node processes.

  3. Restart the cluster, using the `--initial' startup option for all
     instances of `ndbd'.

     *Warning*:

     Never use the `--initial' when starting `ndbd' except when
     necessary to clear the data node filesystem. See *Note
     mysql-cluster-ndbd-command-options::, for information about when
     this is required.

  4. Restore all cluster data from the backup.

In a future MySQL Cluster release series, we hope to implement a `hot'
reconfiguration capability for MySQL Cluster to minimize (if not
eliminate) the requirement for restarting the cluster when adding new
nodes.

*33.10.22: ** Are there any limitations that I should be aware of when
using MySQL Cluster?  *

Limitations on `NDB' tables in MySQL 5.1 (including MySQL Cluster NDB
6.x) include the following:

   * Temporary tables are not supported; a `CREATE TEMPORARY TABLE'
     statement using `ENGINE=NDB' or `ENGINE=NDBCLUSTER' fails with an
     error.

   * The only types of user-defined partitioning supported for `NDB'
     tables are `KEY' and `LINEAR KEY'. (Beginning with MySQL 5.1.12,
     attempting to create an `NDB' table using any other partitioning
     type fails with an error.)

   * `FULLTEXT' indexes and index prefixes are not supported. Only
     complete columns may be indexed.

   * Spatial indexes are not supported (although spatial columns can be
     used). See *Note spatial-extensions::.

   * Only complete rollbacks for transactions are supported.  Partial
     rollbacks and rollbacks to save points are not supported.

   * The maximum number of attributes allowed per table is 128, and
     attribute names cannot be any longer than 31 characters. For each
     table, the maximum combined length of the table and database names
     is 122 characters.

   * The maximum size for a table row is 8 kilobytes, not counting
     `BLOB' values. There is no set limit for the number of rows per
     table. Table size limits depend on a number of factors, in
     particular on the amount of RAM available to each data node.

   * The `NDB' engine does not support foreign key constraints. As with
     `MyISAM' tables, if these are specified in a `CREATE TABLE' or
     `ALTER TABLE' statement, they are ignored.

For a complete listing of limitations in MySQL Cluster, see *Note
mysql-cluster-limitations::.

*33.10.23: ** ** How do I import an existing MySQL database into a MySQL
Cluster?  *

You can import databases into MySQL Cluster much as you would with any
other version of MySQL. Other than the limitations mentioned elsewhere
in this FAQ, the only other special requirement is that any tables to
be included in the cluster must use the `NDB' storage engine.  This
means that the tables must be created with `ENGINE=NDB' or
`ENGINE=NDBCLUSTER'.

It is also possible to convert existing tables using other storage
engines to `NDBCLUSTER' using one or more `ALTER TABLE' statement.
However, the definition of the table must be compatible with the
`NDBCLUSTER' storage engine prior to making the conversion.

See *Note mysql-cluster-limitations::, for details.

*33.10.24: ** How do cluster nodes communicate with one another?  *

Cluster nodes can communicate via any of three different transport
mechanisms: TCP/IP, SHM (shared memory), and SCI (Scalable Coherent
Interface). Where available, SHM is used by default between nodes
residing on the same cluster host; however, this is considered
experimental. SCI is a high-speed (1 gigabit per second and higher),
high-availability protocol used in building scalable multi-processor
systems; it requires special hardware and drivers. See *Note
mysql-cluster-interconnects::, for more about using SCI as a transport
mechanism for MySQL Cluster.

*33.10.25: ** ** ** What is an _arbitrator_?  *

If one or more nodes in a cluster fail, it is possible that not all
cluster nodes will be able to `see' one another. In fact, it is
possible that two sets of nodes might become isolated from one another
in a network partitioning, also known as a `split brain' scenario. This
type of situation is undesirable because each set of nodes tries to
behave as though it is the entire cluster.

When cluster nodes go down, there are two possibilities. If more than
50% of the remaining nodes can communicate with each other, we have
what is sometimes called a `majority rules' situation, and this set of
nodes is considered to be the cluster. The arbitrator comes into play
when there is an even number of nodes: in such cases, the set of nodes
to which the arbitrator belongs is considered to be the cluster, and
nodes not belonging to this set are shut down.

The preceding information is somewhat simplified. A more complete
explanation taking into account node groups follows:

When all nodes in at least one node group are alive, network
partitioning is not an issue, because no one portion of the cluster can
form a functional cluster. The real problem arises when no single node
group has all its nodes alive, in which case network partitioning (the
`split-brain' scenario) becomes possible. Then an arbitrator is
required. All cluster nodes recognize the same node as the arbitrator,
which is normally the management server; however, it is possible to
configure any of the MySQL Servers in the cluster to act as the
arbitrator instead. The arbitrator accepts the first set of cluster
nodes to contact it, and tells the remaining set to shut down.
Arbitrator selection is controlled by the `ArbitrationRank'
configuration parameter for MySQL Server and management server nodes.
(See *Note mysql-cluster-mgm-definition::, for details.)

The role of arbitrator does not in and of itself impose any heavy
demands upon the host so designated, and thus the arbitrator host does
not need to be particularly fast or to have extra memory especially for
this purpose.

*33.10.26: ** ** What data types are supported by MySQL Cluster?  *

MySQL Cluster 5.1, including MySQL CLuster NDB 6.2 and 6.3, supports
all of the usual MySQL data types, including those associated with
MySQL's spatial extensions; however, the `NDBCLUSTER' storage engine
does not support spatial indexes. (Spatial indexes are supported only
by `MyISAM'; see *Note spatial-extensions::, for more information.)  In
addition, there are some differences with regard to indexes when used
with `NDB' tables.

*Note*:

MySQL Cluster Disk Data tables (that is, tables created with
`TABLESPACE ... STORAGE DISK ENGINE=NDBCLUSTER') have only fixed-width
rows.  This means that (for example) each Disk Data table record
containing a `VARCHAR(255)' column requires space for 255 characters
(as required for the character set and collation being used for the
table), regardless of the actual number of characters stored therein.

See *Note mysql-cluster-limitations::, for more information about these
issues.

*33.10.27: ** ** How do I start and stop MySQL Cluster?  *

It is necessary to start each node in the cluster separately, in the
following order:

  1. Start the management node, using the `ndb_mgmd' command.

     You must include the `-f' or `--config-file' option to tell the
     management node where its configuration file can be found.

  2. Start each data node with the `ndbd' command.

     Each data node must be started with the `-c' or `--connect-string'
     option so that the data node knows how to connect to the
     management server.

  3. Start each MySQL Server (SQL node) using your preferred startup
     script, such as `mysqld_safe'.

     Each MySQL Server must be started with the `--ndbcluster' and
     `--ndb-connectstring' options. These options cause mysqld to enable
     `NDBCLUSTER' storage engine support and how to connect to the
     management server.

Each of these commands must be run from a system shell on the machine
housing the affected node. (You do not have to be physically present at
the machine -- a remote login shell can be used for this purpose.) You
can verify that the cluster is running by starting the `NDB' management
client `ndb_mgm' on the machine housing the management node and issuing
the `SHOW' or `ALL STATUS' command.

To shut down a running cluster, issue the command `SHUTDOWN' in the
management client.  Alternatively, you may enter the following command
in a system shell:

     shell> ndb_mgm -e "SHUTDOWN"

(The quotation marks are optional; in addition, the `SHUTDOWN' command
is not case-sensitive.)

Either of these commands causes the `ndb_mgm', `ndb_mgm', and any
`ndbd' processes to terminate gracefully. MySQL servers running as
Cluster SQL nodes can be stopped using `mysqladmin shutdown'.

For more information, see *Note mysql-cluster-mgm-client-commands::, and
*Note mysql-cluster-multi-shutdown-restart::.

*33.10.28: ** What happens to MySQL Cluster data when the cluster is
shut down?  *

The data that was held in memory by the cluster's data nodes is written
to disk, and is reloaded into memory the next time that the cluster is
started.

*33.10.29: ** Is it a good idea to have more than one management node
for a MySQL Cluster?  *

It can be helpful as a fail-safe. Only one management node controls the
cluster at any given time, but it is possible to configure one
management node as primary, and one or more additional management nodes
to take over in the event that the primary management node fails.

See *Note mysql-cluster-config-file::, for information on how to
configure MySQL Cluster management nodes.

*33.10.30: ** Can I mix different kinds of hardware and operating
systems in one MySQL Cluster?  *

Yes, as long as all machines and operating systems have the same
`endianness' (all big-endian or all little-endian). We are working to
overcome this limitation in a future MySQL Cluster release.

It is also possible to use software different MySQL Cluster releases on
different nodes. However, we support this only as part of a rolling
upgrade procedure (see *Note mysql-cluster-rolling-restart::).

*33.10.31: ** Can I run two data nodes on a single host? Two SQL nodes?
*

Yes, it is possible to do this. In the case of multiple data nodes, it
is advisable (but not required) for each node to use a different data
directory. If you want to run multiple SQL nodes on one machine, each
instance of `mysqld' must use a different TCP/IP port.  However,
running more than one cluster node of a given type per machine is
generally not encouraged or supported for production use.

We also advise against running data nodes and SQL nodes together on the
same host, since the `ndbd' and `mysqld' processes may compete for
memory.

*33.10.32: ** Can I use hostnames with MySQL Cluster?  *

Yes, it is possible to use DNS and DHCP for cluster hosts.  However, if
your application requires `five nines' availability, we recommend using
fixed (numeric) IP addresses. Making communication between Cluster
hosts dependent on services such as DNS and DHCP introduces additional
potential points of failure.

*33.10.33: ** How do I handle MySQL users in a MySQL Cluster having
multiple MySQL servers?  *

MySQL user accounts and privileges are not automatically propagated
between different MySQL servers accessing the same MySQL Cluster.
Therefore, you must make sure that these are copied between the SQL
nodes yourself. You can do this manually, or automate the task with
scripts.

*Warning*:

Do not attempt to work around this issue by converting the MySQL system
tables to use the `NDBCLUSTER' storage engine. Only the `MyISAM'
storage engine is supported for these tables.

*33.10.34: ** How do I continue to send queries in the event that one of
the SQL nodes fails?  *

MySQL Cluster does not provide any sort of automatic failover between
SQL nodes. Your application must be prepared to handlethe loss of SQL
nodes and to fail over between them.


File: manual.info,  Node: faqs-cjk,  Next: faqs-connectors-apis,  Prev: faqs-mysql-cluster,  Up: faqs

A.11 MySQL 5.1 FAQ -- MySQL Chinese, Japanese, and Korean Character Sets
========================================================================

This set of Frequently Asked Questions derives from the experience of
MySQL's Support and Development groups in handling many inquiries about
CJK (Chinese-Japanese-Korean) issues.

*Questions*
   * 33.11.1: 

     What CJK character sets are available in MySQL?

   * 33.11.2: I have inserted CJK characters into my table. Why does
     `SELECT' display them as `?' characters?

   * 33.11.3: 

     What problems should I be aware of when working with the Big5
     Chinese character set?

   * 33.11.4: 

     Why do Japanese character set conversions fail?

   * 33.11.5: What should I do if I want to convert SJIS `81CA' to
     `cp932'?

   * 33.11.6: 

     How does MySQL represent the Yen (`¥') sign?

   * 33.11.7: Do MySQL plan to make a separate character set where `5C'
     is the Yen sign, as at least one other major DBMS does?

   * 33.11.8: 

     Of what issues should I be aware when working with Korean
     character sets in MySQL?

   * 33.11.9: 

     Why do I get `Data truncated' error messages?

   * 33.11.10: 

     Why does my GUI front end or browser not display CJK characters
     correctly in my application using Access, PHP, or another API?

   * 33.11.11: 

     I've upgraded to MySQL 5.1. How can I revert to behavior like that
     in MySQL 4.0 with regard to character sets?

   * 33.11.12: 

     Why do some `LIKE' and `FULLTEXT' searches with CJK characters
     fail?

   * 33.11.13: 

     How do I know whether character X is available in all character
     sets?

   * 33.11.14: 

     Why don't CJK strings sort correctly in Unicode? (I)

   * 33.11.15: 

     Why don't CJK strings sort correctly in Unicode? (II)

   * 33.11.16: 

     Why are my supplementary characters rejected by MySQL?

   * 33.11.17: 

     Shouldn't it be `CJKV'?

   * 33.11.18: 

     Does MySQL allow CJK characters to be used in database and table
     names?

   * 33.11.19: 

     Where can I find translations of the MySQL Manual into Chinese,
     Japanese, and Korean?

   * 33.11.20: Where can I get help with CJK and related issues in
     MySQL?

*Questions and Answers* *33.11.1: ** ** ** ** ** ** What CJK character
sets are available in MySQL?  *

The list of CJK character sets may vary depending on your MySQL
version. For example, the `eucjpms' character set was not supported
prior to MySQL 5.0.3.  However, since the name of the applicable
language appears in the `DESCRIPTION' column for every entry in the
`INFORMATION_SCHEMA.CHARACTER_SETS' table, you can obtain a current
list of all the non-Unicode CJK character sets using this query:

     mysql> SELECT CHARACTER_SET_NAME, DESCRIPTION
         -> FROM INFORMATION_SCHEMA.CHARACTER_SETS
         -> WHERE DESCRIPTION LIKE '%Chinese%'
         -> OR DESCRIPTION LIKE '%Japanese%'
         -> OR DESCRIPTION LIKE '%Korean%'
         -> ORDER BY CHARACTER_SET_NAME;
     +--------------------+---------------------------+
     | CHARACTER_SET_NAME | DESCRIPTION               |
     +--------------------+---------------------------+
     | big5               | Big5 Traditional Chinese  |
     | cp932              | SJIS for Windows Japanese |
     | eucjpms            | UJIS for Windows Japanese |
     | euckr              | EUC-KR Korean             |
     | gb2312             | GB2312 Simplified Chinese |
     | gbk                | GBK Simplified Chinese    |
     | sjis               | Shift-JIS Japanese        |
     | ujis               | EUC-JP Japanese           |
     +--------------------+---------------------------+
     8 rows in set (0.01 sec)

(See *Note character-sets-table::, for more information.)

MySQL supports the two common variants of the _GB_ (_Guojia Biaozhun_,
or _National Standard_, or _Simplified Chinese_) character sets which
are official in the People's Republic of China: `gb2312' and `gbk'.
Sometimes people try to insert `gbk' characters into `gb2312', and it
works most of the time because `gbk' is a superset of `gb2312' -- but
eventually they try to insert a rarer Chinese character and it doesn't
work. (See Bug#16072 (http://bugs.mysql.com/16072) for an example).

Here, we try to clarify exactly what characters are legitimate in
`gb2312' or `gbk', with reference to the official documents. Please
check these references before reporting `gb2312' or `gbk' bugs.

   * For a complete listing of the `gb2312' characters, ordered
     according to the `gb2312_chinese_ci' collation: gb2312
     (http://www.collation-charts.org/mysql60/by-charset.html#gb2312)

   * MySQL's `gbk' is in reality `Microsoft code page 936'. This differs
     from the official `gbk' for characters `A1A4' (middle dot), `A1AA'
     (em dash), `A6E0-A6F5', and `A8BB-A8C0'. For a listing of the
     differences, see
     `http://recode.progiciels-bpi.ca/showfile.html?name=dist/libiconv/gbk.h'.

   * For a listing of `gbk'/Unicode mappings, see
     `http://www.unicode.org/Public/MAPPINGS/VENDORS/MICSFT/WINDOWS/CP936.TXT'.

   * For MySQL's listing of `gbk' characters, see gbk
     (http://www.collation-charts.org/mysql60/by-charset.html#gbk).

*33.11.2: ** I have inserted CJK characters into my table. Why does
`SELECT' display them as `?' characters?  *

This problem is usually due to a setting in MySQL that doesn't match
the settings for the application program or the operating system. Here
are some common steps for correcting these types of issues:

   * _Be certain of what MySQL version you are using_.

     Use the statement `SELECT VERSION();' to determine this.

   * _Make sure that the database is actually using the desired
     character set_.

     People often think that the client character set is always the
     same as either the server character set or the character set used
     for display purposes. However, both of these are false
     assumptions. You can make sure by checking the result of `SHOW
     CREATE TABLE TABLENAME' or -- better -- yet by using this
     statement:

          SELECT character_set_name, collation_name
              FROM information_schema.columns
              WHERE table_schema = your_database_name
                  AND table_name = your_table_name
                  AND column_name = your_column_name;

   * _Determine the hexadecimal value of the character or characters
     that are not being displayed correctly_.

     You can obtain this information for a column COLUMN_NAME in the
     table TABLE_NAME using the following query:

          SELECT HEX(COLUMN_NAME)
          FROM TABLE_NAME;

     `3F' is the encoding for the `?' character; this means that `?' is
     the character actually stored in the column. This most often
     happens because of a problem converting a particular character
     from your client character set to the target character set.

   * _Make sure that a round trip possible -- that is, when you select
     LITERAL (or _INTRODUCER HEXADECIMAL-VALUE), you obtain LITERAL as a
     result_.

     For example, the Japanese _Katakana_ character _Pe_ (`ペ'')
     exists in all CJK character sets, and has the code point value
     (hexadecimal coding) `0x30da'. To test a round trip for this
     character, use this query:

          SELECT 'ペ' AS `ペ`;         /* or SELECT _ucs2 0x30da; */

     If the result is not also `ペ', then the round trip has failed.

     For bug reports regarding such failures, we might ask you to
     follow up with `SELECT HEX('ペ');'. Then we can determine whether
     the client encoding is correct.

   * _Make sure that the problem is not with the browser or other
     application, rather than with MySQL_.

     Use the `mysql' client program (on Windows: `mysql.exe') to
     accomplish this task. If `mysql' displays correctly but your
     application doesn't, then your problem is probably due to system
     settings.

     To find out what your settings are, use the `SHOW VARIABLES'
     statement, whose output should resemble what is shown here:

          mysql> SHOW VARIABLES LIKE 'char%';
          +--------------------------+----------------------------------------+
          | Variable_name            | Value                                  |
          +--------------------------+----------------------------------------+
          | character_set_client     | utf8                                   |
          | character_set_connection | utf8                                   |
          | character_set_database   | latin1                                 |
          | character_set_filesystem | binary                                 |
          | character_set_results    | utf8                                   |
          | character_set_server     | latin1                                 |
          | character_set_system     | utf8                                   |
          | character_sets_dir       | /usr/local/mysql/share/mysql/charsets/ |
          +--------------------------+----------------------------------------+
          8 rows in set (0.03 sec)

     These are typical character-set settings for an
     international-oriented client (notice the use of `utf8' Unicode)
     connected to a server in the West (`latin1' is a West Europe
     character set and a default for MySQL).

     Although Unicode (usually the `utf8' variant on Unix, and the
     `ucs2' variant on Windows) is preferable to Latin, it's often not
     what your operating system utilities support best. Many Windows
     users find that a Microsoft character set, such as `cp932' for
     Japanese Windows, is what's suitable.

     If you cannot control the server settings, and you have no idea
     what your underlying computer is, then try changing to a common
     character set for the country that you're in (`euckr' = Korea;
     `gb2312' or `gbk' = People's Republic of China; `big5' = Taiwan;
     `sjis', `ujis', `cp932', or `eucjpms' = Japan; `ucs2' or `utf8' =
     anywhere). Usually it is necessary to change only the client and
     connection and results settings. There is a simple statement which
     changes all three at once: `SET NAMES'. For example:

          SET NAMES 'big5';

     Once the setting is correct, you can make it permanent by editing
     `my.cnf' or `my.ini'. For example you might add lines looking like
     these:

          [mysqld]
          character-set-server=big5
          [client]
          default-character-set=big5

     It is also possible that there are issues with the API
     configuration setting being used in your application; see `Why
     does my GUI front end or browser not display CJK characters
     correctly...?' for more information.

*33.11.3: ** ** ** ** What problems should I be aware of when working
with the Big5 Chinese character set?  *

MySQL supports the Big5 character set which is common in Hong Kong and
Taiwan (Republic of China). MySQL's `big5' is in reality Microsoft code
page 950, which is very similar to the original `big5' character set.
We changed to this

character set starting with MySQL version 4.1.16 / 5.0.16 (as a result
of Bug#12476 (http://bugs.mysql.com/12476)). For example, the following
statements work in current versions of MySQL, but not in old versions:

     mysql> CREATE TABLE big5 (BIG5 CHAR(1) CHARACTER SET BIG5);
     Query OK, 0 rows affected (0.13 sec)

     mysql> INSERT INTO big5 VALUES (0xf9dc);
     Query OK, 1 row affected (0.00 sec)

     mysql> SELECT * FROM big5;
     +------+
     | big5 |
     +------+
     | 嫺  |
     +------+
     1 row in set (0.02 sec)

A feature request for adding `HKSCS' extensions has been filed. People
who need this extension may find the suggested patch for Bug#13577
(http://bugs.mysql.com/13577) to be of interest.

*33.11.4: ** ** ** ** Why do Japanese character set conversions fail?  *

MySQL supports the `sjis', `ujis', `cp932', and eucjpms character sets,
as well as Unicode. A common need is to convert between character sets.
For example, there might be a Unix server (typically with `sjis' or
`ujis') and a Windows client (typically with `cp932').

In the following conversion table, the `ucs2' column represents the
source, and the `sjis', `cp932', `ujis', and `eucjpms' columns
represent the destinations -- that is, the last 4 columns provide the
hexadecimal result when we use `CONVERT(ucs2)' or we assign a `ucs2'
column containing the value to an `sjis', `cp932', `ujis', or `eucjpms'
column.

Character Name                ucs2      sjis      cp932     ujis      eucjpms
BROKEN BAR                    00A6      3F        3F        8FA2C3    3F
FULLWIDTH BROKEN BAR          FFE4      3F        FA55      3F        8FA2
YEN SIGN                      00A5      3F        3F        20        3F
FULLWIDTH YEN SIGN            FFE5      818F      818F      A1EF      3F
TILDE                         007E      7E        7E        7E        7E
OVERLINE                      203E      3F        3F        20        3F
HORIZONTAL BAR                2015      815C      815C      A1BD      A1BD
EM DASH                       2014      3F        3F        3F        3F
REVERSE SOLIDUS               005C      815F      5C        5C        5C
FULLWIDTH ""                  FF3C      3F        815F      3F        A1C0
WAVE DASH                     301C      8160      3F        A1C1      3F
FULLWIDTH TILDE               FF5E      3F        8160      3F        A1C1
DOUBLE VERTICAL LINE          2016      8161      3F        A1C2      3F
PARALLEL TO                   2225      3F        8161      3F        A1C2
MINUS SIGN                    2212      817C      3F        A1DD      3F
FULLWIDTH HYPHEN-MINUS        FF0D      3F        817C      3F        A1DD
CENT SIGN                     00A2      8191      3F        A1F1      3F
FULLWIDTH CENT SIGN           FFE0      3F        8191      3F        A1F1
POUND SIGN                    00A3      8192      3F        A1F2      3F
FULLWIDTH POUND SIGN          FFE1      3F        8192      3F        A1F2
NOT SIGN                      00AC      81CA      3F        A2CC      3F
FULLWIDTH NOT SIGN            FFE2      3F        81CA      3F        A2CC

Now consider this portion of the table:

                                         ucs2        sjis        cp932
NOT SIGN                                 00AC        81CA        3F
FULLWIDTH NOT SIGN                       FFE2        3F          81CA

This means that MySQL converts the `NOT SIGN' (Unicode `U+00AC') to
`sjis' code point `0x81CA' and to `cp932' code point `3F'. (`3F' is the
question mark (`?') -- this is what is always used when the conversion
cannot be performed.

*33.11.5: ** What should I do if I want to convert SJIS `81CA' to
`cp932'?  *

Our answer is: `?'. There are serious complaints about this: many
people would prefer a `loose' conversion, so that `81CA (NOT SIGN)' in
`sjis' becomes `81CA (FULLWIDTH NOT SIGN)' in `cp932'. We are
considering a change to this behavior.

*33.11.6: ** ** ** ** How does MySQL represent the Yen (`¥') sign?  *

A problem arises because some versions of Japanese character sets (both
`sjis' and `euc') treat `5C' as a _reverse solidus_ (`\' -- also known
as a backslash), and others treat it as a yen sign (`¥').

MySQL follows only one version of the JIS (Japanese Industrial
Standards) standard description. In MySQL, _`5C' is always the reverse
solidus (`\')_.

*33.11.7: ** Do MySQL plan to make a separate character set where `5C'
is the Yen sign, as at least one other major DBMS does?  *

This is one possible solution to the Yen sign issue; however, this will
not happen in MySQL 5.1 or 5.2.

*33.11.8: ** ** ** ** Of what issues should I be aware when working
with Korean character sets in MySQL?  *

In theory, while there have been several versions of the `euckr'
(_Extended Unix Code Korea_) character set, only one problem has been
noted.

We use the `ASCII' variant of EUC-KR, in which the code point `0x5c' is
REVERSE SOLIDUS, that is `\', instead of the `KS-Roman' variant of
EUC-KR, in which the code point `0x5c' is `WON SIGN'(`₩'). This means
that you cannot convert Unicode `U+20A9' to `euckr':

     mysql> SELECT
         ->     CONVERT('₩' USING euckr) AS euckr,
         ->     HEX(CONVERT('₩' USING euckr)) AS hexeuckr;
     +-------+----------+
     | euckr | hexeuckr |
     +-------+----------+
     | ?     | 3F       |
     +-------+----------+
     1 row in set (0.00 sec)

MySQL's graphic Korean chart is here: euckr
(http://www.collation-charts.org/mysql60/by-charset.html#euckr).

*33.11.9: ** ** ** ** Why do I get `Data truncated' error messages?  *

For illustration, we'll create a table with one Unicode (`ucs2') column
and one Chinese (`gb2312') column.

     mysql> CREATE TABLE ch
         -> (ucs2 CHAR(3) CHARACTER SET ucs2,
         -> gb2312 CHAR(3) CHARACTER SET gb2312);
     Query OK, 0 rows affected (0.05 sec)

We'll try to place the rare character `汌' in both columns.

     mysql> INSERT INTO ch VALUES ('A汌B','A汌B');
     Query OK, 1 row affected, 1 warning (0.00 sec)

Ah, there's a warning. Let's see what it is.

     mysql> SHOW WARNINGS;
     +---------+------+---------------------------------------------+
     | Level   | Code | Message                                     |
     +---------+------+---------------------------------------------+
     | Warning | 1265 | Data truncated for column 'gb2312' at row 1 |
     +---------+------+---------------------------------------------+
     1 row in set (0.00 sec)

So it's a warning about the `gb2312' column only.

     mysql> SELECT ucs2,HEX(ucs2),gb2312,HEX(gb2312) FROM ch;
     +-------+--------------+--------+-------------+
     | ucs2  | HEX(ucs2)    | gb2312 | HEX(gb2312) |
     +-------+--------------+--------+-------------+
     | A汌B | 00416C4C0042 | A?B    | 413F42      |
     +-------+--------------+--------+-------------+
     1 row in set (0.00 sec)

There are several things that need explanation here.

  1. The fact that it's a `warning' rather than an `error' is
     characteristic of MySQL. We like to try to do what we can, to get
     the best fit, rather than give up.

  2. The `汌' character isn't in the `gb2312' character set. We
     described that problem earlier.

  3. Admittedly the message is misleading. We didn't `truncate' in this
     case, we replaced with a question mark. We've had a complaint
     about this message (See Bug#9337 (http://bugs.mysql.com/9337)).
     But until we come up with something better, just accept that
     error/warning code 2165 can mean a variety of things.

  4. With `SQL_MODE=TRADITIONAL', there would be an error message, but
     instead of error 2165 you would see: `ERROR 1406 (22001): Data too
     long for column 'gb2312' at row 1'.

*33.11.10: ** ** ** Why does my GUI front end or browser not display CJK
characters correctly in my application using Access, PHP, or another
API?  *

Obtain a direct connection to the server using the `mysql' client
(Windows: `mysql.exe'), and try the same query there.  If `mysql'
responds correctly, then the trouble may be that your application
interface requires initialization. Use `mysql' to tell you what
character set or sets it uses with the statement `SHOW VARIABLES LIKE
'char%';'. If you are using Access, then you are most likely connecting
with MyODBC. In this case, you should check *Note
myodbc-configuration::. If, for instance, you use `big5', you would
enter `SET NAMES 'big5''. (Note that no `;' is required in this case).
If you are using ASP, you might need to add `SET NAMES' in the code.
Here is an example that has worked in the past:

     <%
     Session.CodePage=0
     Dim strConnection
     Dim Conn
     strConnection="driver={MySQL ODBC 3.51 Driver};server=SERVER;uid=USERNAME;" \
                    & "pwd=PASSWORD;database=DATABASE;stmt=SET NAMES 'big5';"
     Set Conn = Server.CreateObject("ADODB.Connection")
     Conn.Open strConnection
     %>

In much the same way, if you are using any character set other than
`latin1' with Connector/NET, then you must specify the character set in
the connection string. See *Note connector-net-using-connecting::, for
more information.

If you are using PHP, try this:

     <?php
       $link = mysql_connect($host, $usr, $pwd);

       mysql_select_db($db);

       if( mysql_error() ) { print "Database ERROR: " . mysql_error(); }
       mysql_query("SET NAMES 'utf8'", $link);
     ?>

In this case, we used `SET NAMES' to change `character_set_client' and
`character_set_connection' and `character_set_results'.

We encourage the use of the newer `mysqli' extension, rather than
`mysql'. Using `mysqli', the previous example could be rewritten as
shown here:


     <?php
       $link = new mysqli($host, $usr, $pwd, $db);

       if( mysqli_connect_errno() )
       {
         printf("Connect failed: %s\n", mysqli_connect_error());
         exit();
       }

       $link->query("SET NAMES 'utf8'");
     ?>

Another issue often encountered in PHP applications has to do with
assumptions made by the browser. Sometimes adding or changing a
`<meta>' tag suffices to correct the problem: for example, to insure
that the user agent interprets page content as `UTF-8', you should
include `<meta http-equiv="Content-Type" content="text/html;
charset=utf-8">' in the `<head>' of the HTML page.

If you are using Connector/J, see *Note
connector-j-reference-charsets::.

*33.11.11: ** ** I've upgraded to MySQL 5.1. How can I revert to
behavior like that in MySQL 4.0 with regard to character sets?  *

In MySQL Version 4.0, there was a single `global' character set for
both server and client, and the decision as to which character to use
was made by the server administrator. This changed starting with MySQL
Version 4.1. What happens now is a `handshake', as described in *Note
charset-connection:::

When a client connects, it sends to the server the name of the
character set that it wants to use. The server uses the name to set the
`character_set_client', `character_set_results', and
`character_set_connection' system variables. In effect, the server
performs a `SET NAMES' operation using the character set name.

The effect of this is that you cannot control the client character set
by starting `mysqld' with `--character-set-server=utf8'. However, some
of our Asian customers have said that they prefer the MySQL 4.0
behavior. To make it possible to retain this behavior, we added a
`mysqld' switch, `--character-set-client-handshake', which can be
turned off with `--skip-character-set-client-handshake'. If you start
`mysqld' with `--skip-character-set-client-handshake', then, when a
client connects, it sends to the server the name of the character set
that it wants to use -- however, _the server ignores this request from
the client_.

By way of example, suppose that your favorite server character set is
`latin1' (unlikely in a CJK area, but this is the default value).
Suppose further that the client uses `utf8' because this is what the
client's operating system supports. Now, start the server with `latin1'
as its default character set:

     mysqld --character-set-server=latin1

And then start the client with the default character set `utf8':

     mysql --default-character-set=utf8

The current settings can be seen by viewing the output of `SHOW
VARIABLES':

     mysql> SHOW VARIABLES LIKE 'char%';
     +--------------------------+----------------------------------------+
     | Variable_name            | Value                                  |
     +--------------------------+----------------------------------------+
     | character_set_client     | utf8                                   |
     | character_set_connection | utf8                                   |
     | character_set_database   | latin1                                 |
     | character_set_filesystem | binary                                 |
     | character_set_results    | utf8                                   |
     | character_set_server     | latin1                                 |
     | character_set_system     | utf8                                   |
     | character_sets_dir       | /usr/local/mysql/share/mysql/charsets/ |
     +--------------------------+----------------------------------------+
     8 rows in set (0.01 sec)

Now stop the client, and then stop the server using `mysqladmin'. Then
start the server again, but this time tell it to skip the handshake
like so:

     mysqld --character-set-server=utf8 --skip-character-set-client-handshake

Start the client with `utf8' once again as the default character set,
then display the current settings:

     mysql> SHOW VARIABLES LIKE 'char%';
     +--------------------------+----------------------------------------+
     | Variable_name            | Value                                  |
     +--------------------------+----------------------------------------+
     | character_set_client     | latin1                                 |
     | character_set_connection | latin1                                 |
     | character_set_database   | latin1                                 |
     | character_set_filesystem | binary                                 |
     | character_set_results    | latin1                                 |
     | character_set_server     | latin1                                 |
     | character_set_system     | utf8                                   |
     | character_sets_dir       | /usr/local/mysql/share/mysql/charsets/ |
     +--------------------------+----------------------------------------+
     8 rows in set (0.01 sec)

As you can see by comparing the differing results from `SHOW
VARIABLES', the server ignores the client's initial settings if the
`--skip-character-set-client-handshake' is used.

*33.11.12: ** ** ** Why do some `LIKE' and `FULLTEXT' searches with CJK
characters fail?  *

There is a very simple problem with `LIKE' searches on `BINARY' and
`BLOB' columns: we need to know the end of a character. With multi-byte
character sets, different characters might have different octet
lengths. For example, in `utf8', `A' requires one byte but `ペ'
requires three bytes, as shown here:

     +-------------------------+---------------------------+
     | OCTET_LENGTH(_utf8 'A') | OCTET_LENGTH(_utf8 'ペ') |
     +-------------------------+---------------------------+
     |                       1 |                         3 |
     +-------------------------+---------------------------+
     1 row in set (0.00 sec)

If we don't know where the first character ends, then we don't know
where the second character begins, in which case even very simple
searches such as `LIKE '_A%'' fail. The solution is to use a regular CJK
character set in the first place, or to convert to a CJK character set
before comparing.

This is one reason why MySQL cannot allow encodings of nonexistent
characters. If it is not strict about rejecting bad input, then it has
no way of knowing where characters end.

For `FULLTEXT' searches, we need to know where words begin and end.
With Western languages, this is rarely a problem because most (if not
all) of these use an easy-to-identify word boundary -- the space
character.  However, this is not usually the case with Asian writing. We
could use arbitrary halfway measures, like assuming that all Han
characters represent words, or (for Japanese) depending on changes from
Katakana to Hiragana due to grammatical endings. However, the only sure
solution requires a comprehensive word list, which means that we would
have to include a dictionary in the server for each Asian language
supported. This is simply not feasible.

*33.11.13: ** ** ** How do I know whether character X is available in
all character sets?  *

The majority of simplified Chinese and basic non-halfwidth Japanese
_Kana_ characters appear in all CJK character sets. This stored
procedure accepts a `UCS-2' Unicode character, converts it to all other
character sets, and displays the results in hexadecimal.

     DELIMITER //

     CREATE PROCEDURE p_convert(ucs2_char CHAR(1) CHARACTER SET ucs2)
     BEGIN

     CREATE TABLE tj
                  (ucs2 CHAR(1) character set ucs2,
                   utf8 CHAR(1) character set utf8,
                   big5 CHAR(1) character set big5,
                   cp932 CHAR(1) character set cp932,
                   eucjpms CHAR(1) character set eucjpms,
                   euckr CHAR(1) character set euckr,
                   gb2312 CHAR(1) character set gb2312,
                   gbk CHAR(1) character set gbk,
                   sjis CHAR(1) character set sjis,
                   ujis CHAR(1) character set ujis);

     INSERT INTO tj (ucs2) VALUES (ucs2_char);

     UPDATE tj SET utf8=ucs2,
                   big5=ucs2,
                   cp932=ucs2,
                   eucjpms=ucs2,
                   euckr=ucs2,
                   gb2312=ucs2,
                   gbk=ucs2,
                   sjis=ucs2,
                   ujis=ucs2;

     /* If there's a conversion problem, UPDATE will produce a warning. */

     SELECT hex(ucs2) AS ucs2,
            hex(utf8) AS utf8,
            hex(big5) AS big5,
            hex(cp932) AS cp932,
            hex(eucjpms) AS eucjpms,
            hex(euckr) AS euckr,
            hex(gb2312) AS gb2312,
            hex(gbk) AS gbk,
            hex(sjis) AS sjis,
            hex(ujis) AS ujis
     FROM tj;

     DROP TABLE tj;

     END//

The input can be any single `ucs2' character, or it can be the code
point value (hexadecimal representation) of that character. For
example, from Unicode's list of `ucs2' encodings and names
(`http://www.unicode.org/Public/UNIDATA/UnicodeData.txt'), we know that
the _Katakana_ character _Pe_ appears in all CJK character sets, and
that its code point value is `0x30da'. If we use this value as the
argument to `p_convert()', the result is as shown here:

     mysql> CALL p_convert(0x30da)//
     +------+--------+------+-------+---------+-------+--------+------+------+------+
     | ucs2 | utf8   | big5 | cp932 | eucjpms | euckr | gb2312 | gbk  | sjis | ujis |
     +------+--------+------+-------+---------+-------+--------+------+------+------+
     | 30DA | E3839A | C772 | 8379  | A5DA    | ABDA  | A5DA   | A5DA | 8379 | A5DA |
     +------+--------+------+-------+---------+-------+--------+------+------+------+
     1 row in set (0.04 sec)

Since none of the column values is `3F' -- that is, the question mark
character (`?') -- we know that every conversion worked.

*33.11.14: ** ** ** ** ** Why don't CJK strings sort correctly in
Unicode? (I) *

Sometimes people observe that the result of a `utf8_unicode_ci' or
`ucs2_unicode_ci' search, or of an `ORDER BY' sort is not what they
think a native would expect. Although we never rule out the possibility
that there is a bug, we have found in the past that many people do not
read correctly the standard table of weights for the Unicode Collation
Algorithm. MySQL uses the table found at
`http://www.unicode.org/Public/UCA/4.0.0/allkeys-4.0.0.txt'.  This is
not the first table you will find by navigating from the `unicode.org'
home page, because MySQL uses the older 4.0.0 `allkeys' table, rather
than the more recent 4.1.0 table. This is because we are very wary
about changing ordering which affects indexes, lest we bring about
situations such as that reported in Bug#16526
(http://bugs.mysql.com/16526), illustrated as follows:

     mysql< CREATE TABLE tj (s1 CHAR(1) CHARACTER SET utf8 COLLATE utf8_unicode_ci);
     Query OK, 0 rows affected (0.05 sec)

     mysql> INSERT INTO tj VALUES ('が'),('か');
     Query OK, 2 rows affected (0.00 sec)
     Records: 2  Duplicates: 0  Warnings: 0

     mysql> SELECT * FROM tj WHERE s1 = 'か';
     +------+
     | s1   |
     +------+
     | が  |
     | か  |
     +------+
     2 rows in set (0.00 sec)

The character in the first result row is not the one that we searched
for. Why did MySQL retrieve it? First we look for the Unicode code
point value, which is possible by reading the hexadecimal number for
the `ucs2' version of the characters:

     mysql> SELECT s1, HEX(CONVERT(s1 USING ucs2)) FROM tj;
     +------+-----------------------------+
     | s1   | HEX(CONVERT(s1 USING ucs2)) |
     +------+-----------------------------+
     | が  | 304C                        |
     | か  | 304B                        |
     +------+-----------------------------+
     2 rows in set (0.03 sec)

Now we search for `304B' and `304C' in the `4.0.0 allkeys' table, and
find these lines:

     304B  ; [.1E57.0020.000E.304B] # HIRAGANA LETTER KA
     304C  ; [.1E57.0020.000E.304B][.0000.0140.0002.3099] # HIRAGANA LETTER GA; QQCM

The official Unicode names (following the `#' mark) tell us the
Japanese syllabary (Hiragana), the informal classification (letter,
digit, or punctuation mark), and the Western identifier (`KA' or `GA',
which happen to be voiced and unvoiced components of the same letter
pair). More importantly, the _primary weight_ (the first hexadecimal
number inside the square brackets) is `1E57' on both lines. For
comparisons in both searching and sorting, MySQL pays attention to the
primary weight only, ignoring all the other numbers. This means that we
are sorting `が' and `か' correctly according to the Unicode
specification. If we wanted to distinguish them, we'd have to use a
non-UCA (Unicode Collation Algorithm) collation (`utf8_bin' or
`utf8_general_ci'), or to compare the `HEX()' values, or use `ORDER BY
CONVERT(s1 USING sjis)'. Being correct `according to Unicode' isn't
enough, of course: the person who submitted the bug was equally
correct. We plan to add another collation for Japanese according to the
JIS X 4061 standard, in which voiced/unvoiced letter pairs like
`KA'/`GA' are distinguishable for ordering purposes.

*33.11.15: ** ** ** ** ** ** Why don't CJK strings sort correctly in
Unicode? (II) *

If you are using Unicode (`ucs2' or `utf8'), and you know what the
Unicode sort order is (see *Note faqs-cjk::), but MySQL still seems to
sort your table incorrectly, then you should first verify the table
character set:

     mysql> SHOW CREATE TABLE t\G
     ******************** 1. row ******************
     Table: t
     Create Table: CREATE TABLE `t` (
     `s1` char(1) CHARACTER SET ucs2 DEFAULT NULL
     ) ENGINE=MyISAM DEFAULT CHARSET=latin1
     1 row in set (0.00 sec)

Since the character set appears to be correct, let's see what
information the `INFORMATION_SCHEMA.COLUMNS' table can provide about
this column:

     mysql> SELECT COLUMN_NAME, CHARACTER_SET_NAME, COLLATION_NAME
         -> FROM INFORMATION_SCHEMA.COLUMNS
         -> WHERE COLUMN_NAME = 's1'
         -> AND TABLE_NAME = 't';
     +-------------+--------------------+-----------------+
     | COLUMN_NAME | CHARACTER_SET_NAME | COLLATION_NAME  |
     +-------------+--------------------+-----------------+
     | s1          | ucs2               | ucs2_general_ci |
     +-------------+--------------------+-----------------+
     1 row in set (0.01 sec)

(See *Note columns-table::, for more information.)

You can see that the collation is `ucs2_general_ci' instead of
`ucs2_unicode_ci'. The reason why this is so can be found using `SHOW
CHARSET', as shown here:

     mysql> SHOW CHARSET LIKE 'ucs2%';
     +---------+---------------+-------------------+--------+
     | Charset | Description   | Default collation | Maxlen |
     +---------+---------------+-------------------+--------+
     | ucs2    | UCS-2 Unicode | ucs2_general_ci   |      2 |
     +---------+---------------+-------------------+--------+
     1 row in set (0.00 sec)

For `ucs2' and `utf8', the default collation is `general'. To specify a
Unicode collation, use `COLLATE ucs2_unicode_ci'.

*33.11.16: ** ** Why are my supplementary characters rejected by MySQL?
*

Before MySQL 6.0.4, MySQL does not support supplementary characters --
that is, characters which need more than 3 bytes -- for `UTF-8'. We
support only what Unicode calls the _Basic Multilingual Plane / Plane
0_. Only a few very rare Han characters are supplementary; support for
them is uncommon.  This has led to reports such as that found in
Bug#12600 (http://bugs.mysql.com/12600), which we rejected as `not a
bug'. With `utf8', we must truncate an input string when we encounter
bytes that we don't understand. Otherwise, we wouldn't know how long
the bad multi-byte character is.

One possible workaround is to use `ucs2' instead of `utf8', in which
case the `bad' characters are changed to question marks; however, no
truncation takes place. You can also change the data type to `BLOB' or
`BINARY', which perform no validity checking.

As of MySQL 6.0.4, Unicode support is extended to include supplementary
characters by means of additional Unicode character sets: `utf16',
`utf32', and 4-byte `utf8'. These character sets support supplementary
Unicode characters outside the Basic Multilingual Plane (BMP).

*33.11.17: ** ** ** ** Shouldn't it be `CJKV'?  *

No. The term `CJKV' (_Chinese Japanese Korean Vietnamese_) refers to
Vietnamese character sets which contain Han (originally Chinese)
characters. MySQL has no plan to support the old Vietnamese script
using Han characters. MySQL does of course support the modern
Vietnamese script with Western characters.

Bug#4745 (http://bugs.mysql.com/4745) is a request for a specialized
Vietnamese collation, which we might add in the future if there is
sufficient demand for it.

*33.11.18: ** ** Does MySQL allow CJK characters to be used in database
and table names?  *

This issue is fixed in MySQL 5.1, by automatically rewriting the names
of the corresponding directories and files.

For example, if you create a database named `楮' on a server whose
operating system does not support CJK in directory names, MySQL creates
a directory named `@0w@00a5@00ae'. which is just a fancy way of
encoding `E6A5AE' -- that is, the Unicode hexadecimal representation for
the `楮' character. However, if you run a `SHOW DATABASES' statement,
you can see that the database is listed as `楮'.

*33.11.19: ** ** ** ** ** ** **** Where can I find translations of the
MySQL Manual into Chinese, Japanese, and Korean?  *

A Simplified Chinese version of the Manual, current for MySQL 5.1.12,
can be found at `http://dev.mysql.com/doc/'. The Japanese translation
of the MySQL 4.1 manual can be downloaded from
`http://dev.mysql.com/doc/'.

*33.11.20: ** Where can I get help with CJK and related issues in MySQL?
*

The following resources are available:

   * A listing of MySQL user groups can be found at
     `http://dev.mysql.com/user-groups/'.

   * You can contact a sales engineer at the MySQL KK Japan office
     using any of the following:

          Tel: +81(0)3-5326-3133
          Fax: +81(0)3-5326-3001
          Email: dsaito@mysql.com

   * View feature requests relating to character set issues at
     `http://tinyurl.com/y6xcuf'.

   * Visit the MySQL Collation Unicode Forum. We are also in the
     process of adding foreign-language forums at
     `http://forums.mysql.com/'.


File: manual.info,  Node: faqs-connectors-apis,  Next: faqs-replication,  Prev: faqs-cjk,  Up: faqs

A.12 MySQL 5.1 FAQ -- Connectors & APIs
=======================================

For common questions, issues, and answers relating to the MySQL
Connectors and other APIs, see the following areas of the Manual:

   * *Note c-api-problems::

   * *Note php-problems::

   * *Note myodbc-usagenotes::

   * *Note connector-net-using::

   * *Note connector-j-usagenotes::

   * *Note connector-mxj-usagenotes::


File: manual.info,  Node: faqs-replication,  Next: faqs-mysql-drbd-heartbeat,  Prev: faqs-connectors-apis,  Up: faqs

A.13 MySQL 5.1 FAQ -- Replication
=================================

For answers to common queries and question regarding Replication within
MySQL, see *Note replication-faq::.


File: manual.info,  Node: faqs-mysql-drbd-heartbeat,  Prev: faqs-replication,  Up: faqs

A.14 MySQL 5.1 FAQ -- MySQL, DRBD, and Heartbeat
================================================

* Menu:

* faqs-drbd::                    Distributed Replicated Block Device (DRBD)
* drbd-linux-heartbeat::         Linux Heartbeat
* drbd-architecture::            DRBD Architecture
* drbd-mysql-replication-scale::  DRBD and MySQL Replication
* drbd-file-systems::            DRBD and File Systems
* drbd-lvm::                     DRBD and LVM
* drbd-virtualization::          DRBD and Virtualization
* drbd-security::                DRBD and Security
* drbd-system-requirements::     DRBD and System Requirements
* drbd-support-consulting::      DBRD and Support and Consulting


File: manual.info,  Node: faqs-drbd,  Next: drbd-linux-heartbeat,  Prev: faqs-mysql-drbd-heartbeat,  Up: faqs-mysql-drbd-heartbeat

A.14.1 Distributed Replicated Block Device (DRBD)
-------------------------------------------------

In the following section, we provide answers to questions that are most
frequently asked about Distributed Replicated Block Device (DRBD).

*Questions*
   * 33.14.1.1: 

     What is DRBD?

   * 33.14.1.2: What are `Block Devices'?

   * 33.14.1.3: 

     How is DRBD licensed?

   * 33.14.1.4: Where can I download DRBD?

   * 33.14.1.5: If I find a bug in DRBD, to whom do I submit the issue?

   * 33.14.1.6: Where can I get more technical and business information
     concerning MySQL and DRBD?

*Questions and Answers* *33.14.1.1: ** ** What is DRBD?  *

DRBD is an acronym for Distributed Replicated Block Device. DRBD is an
open source Linux kernel block device which leverages synchronous
replication to achieve a consistent view of data between two systems,
typically an Active and Passive system. DRBD currently supports all the
major flavors of Linux and comes bundled in several major Linux
distributions. The DRBD project is maintained by LINBIT
(http://www.drbd.org/).

*33.14.1.2: ** What are `Block Devices'?  *

Block devices are the type of device used to represent storage in the
Linux Kernel. All physical disk devices present a `block device'
interface.  Additionally, virtual disk systems like LVM or DRBD present
a `block device' interface. In this way, the file system or other
software that might want to access a disk device can be used with any
number of real or virtual devices without having to know anything about
their underlying implementation details.

*33.14.1.3: ** ** How is DRBD licensed?  *

DRBD is licensed under the GPL.

*33.14.1.4: ** Where can I download DRBD?  *

Please see `http://www.drbd.org/download.html'

*33.14.1.5: ** If I find a bug in DRBD, to whom do I submit the issue?
*

Bug reports should be submitted to the DRBD mailing list.  Please see:
`http://lists.linbit.com/'.

*33.14.1.6: ** Where can I get more technical and business information
concerning MySQL and DRBD?  *

Please visit: `http://mysql.com/drbd/'


File: manual.info,  Node: drbd-linux-heartbeat,  Next: drbd-architecture,  Prev: faqs-drbd,  Up: faqs-mysql-drbd-heartbeat

A.14.2 Linux Heartbeat
----------------------

In the following section, we provide answers to questions that are most
frequently asked about Linux Heartbeat.

*Questions*
   * 33.14.2.1: What is Linux Heartbeat?

   * 33.14.2.2: How is Linux Heartbeat licensed?

   * 33.14.2.3: Where can I download Linux Heartbeat?

   * 33.14.2.4: If I find a bug with Linux Heartbeat, to whom do I
     submit the issue?

*Questions and Answers* *33.14.2.1: ** What is Linux Heartbeat?  *

The Linux-HA project (`http://www.linux-ha.org/') offers a high
availability solution commonly referred to as Linux Heartbeat. Linux
Heartbeat ships as part of several Linux distributions, as well as
within several embedded high availability systems. This solution can
also be used for other applications besides databases servers, such as
mail servers, web servers, file servers, and DNS servers.

Linux Heartbeat implements a heartbeat-protocol. A heartbeat-protocol
means that messages are sent at regular intervals between two or more
nodes. If a message is not received from a node within a given
interval, then it is assumed the node has failed and some type of
failover or recovery action is required. Linux Heartbeat is typically
configured to send these heartbeat messages over standard Ethernet
interfaces, but it does also support other methods, such as serial-line
links.

*33.14.2.2: ** How is Linux Heartbeat licensed?  *

Linux Heartbeat is licensed under the GPL.

*33.14.2.3: ** Where can I download Linux Heartbeat?  *

Please see `http://linux-ha.org/download/index.html'.

*33.14.2.4: ** If I find a bug with Linux Heartbeat, to whom do I submit
the issue?  *

Bug reports should be submitted to
`http://www.linux-ha.org/ClusterResourceManager/BugReports'.


File: manual.info,  Node: drbd-architecture,  Next: drbd-mysql-replication-scale,  Prev: drbd-linux-heartbeat,  Up: faqs-mysql-drbd-heartbeat

A.14.3 DRBD Architecture
------------------------

In the following section, we provide answers to questions that are most
frequently asked about DRBD Architecture.

*Questions*
   * 33.14.3.1: Is an Active/Active option available for MySQL with
     DRBD?

   * 33.14.3.2: What MySQL storage engines are supported with DRBD?

   * 33.14.3.3: How long does a failover take?

   * 33.14.3.4: How long does it take to resynchronize data after a
     failure?

   * 33.14.3.5: Are there any situations where you shouldn't use DRBD?

   * 33.14.3.6: Are there any limitations to DRBD?

   * 33.14.3.7: Where can I find more information on sample
     architectures?

*Questions and Answers* *33.14.3.1: ** Is an Active/Active option
available for MySQL with DRBD?  *

Currently, MySQL does not support Active/Active configurations using
DRBD `out of the box'.

*33.14.3.2: ** What MySQL storage engines are supported with DRBD?  *

All of the MySQL transactional storage engines are supported by DRBD,
including InnoDB and Falcon. For archived or read-only data, MyISAM or
Archive can also be used.

*33.14.3.3: ** How long does a failover take?  *

Failover time is dependent on many things, some of which are
configurable. After activating the passive host, MySQL will have to
start and run a normal recovery process. If the InnoDB log files have
been configured to a large size and there was heavy write traffic, this
may take a reasonably long period of time. However, under normal
circumstances, failover tends to take less than a minute.

*33.14.3.4: ** How long does it take to resynchronize data after a
failure?  *

Resynchronization time depends on how long the two machines are out of
communication and how much data was written during that period of time.
Resynchronization time is a function of data to be synced, network
speed and disk speed. DRBD maintains a bitmap of changed blocks on the
primary machine, so only those blocks that have changed will need to be
transferred.

*33.14.3.5: ** Are there any situations where you shouldn't use DRBD?  *

See When Not To Use DRBD
(http://fghaas.wordpress.com/2007/06/26/when-not-to-use-drbd/).

*33.14.3.6: ** Are there any limitations to DRBD?  *

See DRBD limitations (or are they?)
(http://fghaas.wordpress.com/2007/06/18/drbd-limitations-or-are-they/).

*33.14.3.7: ** Where can I find more information on sample
architectures?  *

For an example of a Heartbeat R1-compatible resource configuration
involving a MySQL database backed by DRBD, see DRBD User's Guide
(http://www.drbd.org/users-guide/s-heartbeat-r1.html).

For an example of the same DRBD-backed configuration for a MySQL
database in a Heartbeat CRM cluster, see DRBD User's Guide
(http://www.drbd.org/users-guide/s-heartbeat-crm.html).


File: manual.info,  Node: drbd-mysql-replication-scale,  Next: drbd-file-systems,  Prev: drbd-architecture,  Up: faqs-mysql-drbd-heartbeat

A.14.4 DRBD and MySQL Replication
---------------------------------

In the following section, we provide answers to questions that are most
frequently asked about MySQL Replication Scale-out.

*Questions*
   * 33.14.4.1: What is the difference between MySQL Cluster and DRBD?

   * 33.14.4.2: What is the difference between MySQL Replication and
     DRBD?

   * 33.14.4.3: How can I combine MySQL Replication scale-out with DRBD?

*Questions and Answers* *33.14.4.1: ** What is the difference between
MySQL Cluster and DRBD?  *

Both MySQL Cluster and DRBD replicate data synchronously.  MySQL
Cluster leverages a shared-nothing storage architecture in which the
cluster can be architected beyond an Active/Passive configuration. DRBD
operates at a much lower level within the `stack', at the disk I/O
level. For a comparison of various high availability features between
these two options, please refer to *Note ha-overview::.

*33.14.4.2: ** What is the difference between MySQL Replication and
DRBD?  *

MySQL Replication replicates data asynchronously while DRBD replicates
data synchronously. Also, MySQL Replication replicates MySQL
statements, while DRBD replicates the underlying block device that
stores the MySQL data files. For a comparison of various high
availability features between these two options, please refer to the
high availability comparison grid, *Note ha-overview::.

*33.14.4.3: ** How can I combine MySQL Replication scale-out with DRBD?
*

MySQL Replication is typically deployed in a Master to many Slaves
configuration. In this configuration, having many Slaves provides read
scalability. DRBD is used to provide high-availability for the Master
MySQL Server in an Active/Passive configuration. This provides for
automatic failover, safeguards against data loss, and automatically
synchronizes the failed MySQL Master after a failover.

The most likely scenario in which MySQL Replication scale-out can be
leveraged with DRBD is in the form of attaching replicated MySQL
`read-slaves' off of the Active-Master MySQL Server, shown in *Note
active-master-mysql-server::. Since DRBD replicates an entire block
device, master information such as the binary logs are also replicated.
In this way, all of the slaves can attach to the Virtual IP Address
managed by Linux Heartbeat. In the event of a failure, the asynchronous
nature of MySQL Replication allows the slaves to continue with the new
Active machine as their master with no intervention needed.

FIGURE GOES HERE: Active-Master MySQL server


File: manual.info,  Node: drbd-file-systems,  Next: drbd-lvm,  Prev: drbd-mysql-replication-scale,  Up: faqs-mysql-drbd-heartbeat

A.14.5 DRBD and File Systems
----------------------------

In the following section, we provide answers to questions that are most
frequently asked about DRBD and file systems.

*Questions*
   * 33.14.5.1: Can XFS be used with DRBD?

*Questions and Answers* *33.14.5.1: ** Can XFS be used with DRBD?  *

Yes. XFS uses dynamic block size, thus DRBD 0.7 or later is needed.


File: manual.info,  Node: drbd-lvm,  Next: drbd-virtualization,  Prev: drbd-file-systems,  Up: faqs-mysql-drbd-heartbeat

A.14.6 DRBD and LVM
-------------------

In the following section, we provide answers to questions that are most
frequently asked about DRBD and LVM.

*Questions*
   * 33.14.6.1: Can I use DRBD on top of LVM?

   * 33.14.6.2: Can I use LVM on top of DRBD?

   * 33.14.6.3: Can I use DRBD on top of LVM while at the same time
     running LVM on top of that DRBD?

*Questions and Answers* *33.14.6.1: ** Can I use DRBD on top of LVM?  *

Yes, DRBD supports on-line resizing. If you enlarge your logical volume
that acts as a backing device for DRBD, you can enlarge DRBD itself
too, and of course your file system if it supports resizing.

*33.14.6.2: ** Can I use LVM on top of DRBD?  *

Yes, you can use DRBD as a Physical Volume (PV) for LVM.  Depending on
the default LVM configuration shipped with your distribution, you may
need to add the `/dev/drbd*' device files to the `filter' option in your
`lvm.conf' so LVM scans your DRBDs for PV signatures.

*33.14.6.3: ** Can I use DRBD on top of LVM while at the same time
running LVM on top of that DRBD?  *

This requires careful tuning of your LVM configuration to avoid
duplicate PV scans, but yes, it is possible.


File: manual.info,  Node: drbd-virtualization,  Next: drbd-security,  Prev: drbd-lvm,  Up: faqs-mysql-drbd-heartbeat

A.14.7 DRBD and Virtualization
------------------------------

In the following section, we provide answers to questions that are most
frequently asked about DRBD and virtualization.

*Questions*
   * 33.14.7.1: Can I use DRBD with OpenVZ?

   * 33.14.7.2: Can I use DRBD with Xen and/or KVM?

*Questions and Answers* *33.14.7.1: ** Can I use DRBD with OpenVZ?  *

See `http://wiki.openvz.org/HA_cluster_with_DRBD_and_Heartbeat'.

*33.14.7.2: ** Can I use DRBD with Xen and/or KVM?  *

Yes. If you are looking for professional consultancy or expert
commercial support for Xen- or KVM-based virtualization clusters with
DRBD, contact LINBIT (`http://www.linbit.com').


File: manual.info,  Node: drbd-security,  Next: drbd-system-requirements,  Prev: drbd-virtualization,  Up: faqs-mysql-drbd-heartbeat

A.14.8 DRBD and Security
------------------------

In the following section, we provide answers to questions that are most
frequently asked about DRBD and security.

*Questions*
   * 33.14.8.1: Can I encrypt/compress the exchanged data?

   * 33.14.8.2: Does DRBD do mutual node authentication?

*Questions and Answers* *33.14.8.1: ** Can I encrypt/compress the
exchanged data?  *

Yes. But there is no option within DRBD to allow for this.  You'll need
to leverage a VPN and the network layer should do the rest.

*33.14.8.2: ** Does DRBD do mutual node authentication?  *

Yes, starting with DRBD 8 shared-secret mutual node authentication is
supported.


File: manual.info,  Node: drbd-system-requirements,  Next: drbd-support-consulting,  Prev: drbd-security,  Up: faqs-mysql-drbd-heartbeat

A.14.9 DRBD and System Requirements
-----------------------------------

In the following section, we provide answers to questions that are most
frequently asked about DRBD and System Requirements.

*Questions*
   * 33.14.9.1: What other packages besides DRBD are required?

   * 33.14.9.2: How many machines are required to set up DRBD?

   * 33.14.9.3: Does DRBD only run on Linux?

*Questions and Answers* *33.14.9.1: ** What other packages besides DRBD
are required?  *

When using pre-built binary packages, none except a matching kernel,
plus packages for `glibc' and your favorite shell. When compiling DRBD
from source additional prerequisite packages may be required. They
include but are not limited to:

   * glib-devel

   * openssl

   * devel

   * libgcrypt-devel

   * glib2-devel

   * pkgconfig

   * ncurses-devel

   * rpm-build

   * rpm-devel

   * redhat-rpm-config

   * gcc

   * gcc-c++

   * bison

   * flex

   * gnutls-devel

   * lm_sensors-devel

   * net-snmp-devel

   * python-devel

   * bzip2-devel

   * libselinux-devel

   * perl-DBI

   * libnet

Pre-built x86 and x86_64 packages for specific kernel versions are
available with a support subscription from LINBIT. Please note that if
the kernel is upgraded, DRBD must be as well.

*33.14.9.2: ** How many machines are required to set up DRBD?  *

Two machines are required to achieve the minimum degree of high
availability. Although at any one given point in time one will be
primary and one will be secondary, it is better to consider the
machines as part of a mirrored pair without a `natural' primary machine.

*33.14.9.3: ** Does DRBD only run on Linux?  *

DRBD is a Linux Kernel Module, and can work with many popular Linux
distributions. DRBD is currently not available for non-Linux operating
systems.


File: manual.info,  Node: drbd-support-consulting,  Prev: drbd-system-requirements,  Up: faqs-mysql-drbd-heartbeat

A.14.10 DBRD and Support and Consulting
---------------------------------------

In the following section, we provide answers to questions that are most
frequently asked about DRBD and resources.

*Questions*
   * 33.14.10.1: Does MySQL offer professional consulting to help with
     designing a DRBD system?

   * 33.14.10.2: Does MySQL offer support for DRBD and Linux Heartbeat
     from MySQL?

   * 33.14.10.3: Are pre-built binaries or RPMs available?

   * 33.14.10.4: Does MySQL have documentation to help me with the
     installation and configuration of DRBD and Linux Heartbeat?

   * 33.14.10.5: Is there a dedicated discussion forum for MySQL
     High-Availability?

   * 33.14.10.6: Where can I get more information about MySQL for DRBD?

*Questions and Answers* *33.14.10.1: ** Does MySQL offer professional
consulting to help with designing a DRBD system?  *

Yes. MySQL offers consulting for the design, installation,
configuration, and monitoring of high availability DRBD.  For more
information concerning a High Availability Jumpstart, please see:
`http://www.mysql.com/consulting/packaged/scaleout.html'.

*33.14.10.2: ** Does MySQL offer support for DRBD and Linux Heartbeat
from MySQL?  *

Yes. Support for DRBD and Linux Heartbeat is available with an add-on
subscription to MySQL Enterprise called `DRBD for MySQL'. For more
information about support options for DRBD see:
`http://mysql.com/products/enterprise/features.html'.

For the list of supported Linux distributions, please see:
`http://www.mysql.com/support/supportedplatforms/enterprise.html'.

*Note*:

DRBD is only available on Linux. DRBD is not available on Windows,
MacOS, Solaris, HPUX, AIX, FreeBSD, or other non-Linux platforms.

*33.14.10.3: ** Are pre-built binaries or RPMs available?  *

Yes. `DRBD for MySQL' is an add-on subscription to MySQL Enterprise,
which provides pre-built binaries for DRBD. For more information, see:
`http://mysql.com/products/enterprise/features.html'.

*33.14.10.4: ** Does MySQL have documentation to help me with the
installation and configuration of DRBD and Linux Heartbeat?  *

For MySQL-specific DRBD documentation, see *Note ha-drbd::.

For general DRBD documentation, see DRBD User's Guide
(http://www.drbd.org/users-guide/).

*33.14.10.5: ** Is there a dedicated discussion forum for MySQL
High-Availability?  *

Yes, `http://forums.mysql.com/list.php?144'.

*33.14.10.6: ** Where can I get more information about MySQL for DRBD?
*

For more information about MySQL for DRBD, including a technical white
paper please see: DRBD for MySQL High Availability
(http://www.mysql.com/products/enterprise/drbd.html).


File: manual.info,  Node: error-handling,  Next: news,  Prev: faqs,  Up: Top

Appendix B Errors, Error Codes, and Common Problems
***************************************************

* Menu:

* problems::                     Problems and Common Errors
* error-messages-server::        Server Error Codes and Messages
* error-messages-client::        Client Error Codes and Messages

This appendix lists common problems and errors that may occur and
potential resolutions, in addition to listing the errors that may
appear when you call MySQL from any host language. The first section
covers problems and resolutions. Detailed information on errors is
provided; The first list displays server error messages. The second
list displays client program messages.

MySQL Enterprise

The MySQL Enterprise Monitor provides a `Virtual DBA' to assist with
problem solving. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: problems,  Next: error-messages-server,  Prev: error-handling,  Up: error-handling

B.1 Problems and Common Errors
==============================

* Menu:

* what-is-crashing::             How to Determine What Is Causing a Problem
* common-errors::                Common Errors When Using MySQL Programs
* installation-issues::          Installation-Related Issues
* administration-issues::        Administration-Related Issues
* query-issues::                 Query-Related Issues
* optimizer-issues::             Optimizer-Related Issues
* table-definition-issues::      Table Definition-Related Issues
* bugs::                         Known Issues in MySQL

This section lists some common problems and error messages that you may
encounter. It describes how to determine the causes of the problems and
what to do to solve them.


File: manual.info,  Node: what-is-crashing,  Next: common-errors,  Prev: problems,  Up: problems

B.1.1 How to Determine What Is Causing a Problem
------------------------------------------------

When you run into a problem, the first thing you should do is to find
out which program or piece of equipment is causing it:

   * If you have one of the following symptoms, then it is probably a
     hardware problems (such as memory, motherboard, CPU, or hard disk)
     or kernel problem:

        * The keyboard doesn't work. This can normally be checked by
          pressing the Caps Lock key. If the Caps Lock light doesn't
          change, you have to replace your keyboard.  (Before doing
          this, you should try to restart your computer and check all
          cables to the keyboard.)

        * The mouse pointer doesn't move.

        * The machine doesn't answer to a remote machine's pings.

        * Other programs that are not related to MySQL don't behave
          correctly.

        * Your system restarted unexpectedly. (A faulty user-level
          program should never be able to take down your system.)

     In this case, you should start by checking all your cables and run
     some diagnostic tool to check your hardware! You should also check
     whether there are any patches, updates, or service packs for your
     operating system that could likely solve your problem. Check also
     that all your libraries (such as `glibc') are up to date.

     It's always good to use a machine with ECC memory to discover
     memory problems early.

   * If your keyboard is locked up, you may be able to recover by
     logging in to your machine from another machine and executing
     `kbd_mode -a'.

   * Please examine your system log file (`/var/log/messages' or
     similar) for reasons for your problem. If you think the problem is
     in MySQL, you should also examine MySQL's log files. See *Note
     log-files::.

   * If you don't think you have hardware problems, you should try to
     find out which program is causing problems. Try using `top', `ps',
     Task Manager, or some similar program, to check which program is
     taking all CPU or is locking the machine.

   * Use `top', `df', or a similar program to check whether you are out
     of memory, disk space, file descriptors, or some other critical
     resource.

   * If the problem is some runaway process, you can always try to kill
     it. If it doesn't want to die, there is probably a bug in the
     operating system.

If after you have examined all other possibilities and you have
concluded that the MySQL server or a MySQL client is causing the
problem, it's time to create a bug report for our mailing list or our
support team. In the bug report, try to give a very detailed
description of how the system is behaving and what you think is
happening. You should also state why you think that MySQL is causing
the problem. Take into consideration all the situations in this
chapter. State any problems exactly how they appear when you examine
your system. Use the `copy and paste' method for any output and error
messages from programs and log files.

Try to describe in detail which program is not working and all symptoms
you see. We have in the past received many bug reports that state only
`the system doesn't work.' This doesn't provide us with any information
about what could be the problem.

If a program fails, it's always useful to know the following
information:

   * Has the program in question made a segmentation fault (did it dump
     core)?

   * Is the program taking up all available CPU time? Check with `top'.
     Let the program run for a while, it may simply be evaluating
     something computationally intensive.

   * If the `mysqld' server is causing problems, can you get any
     response from it with `mysqladmin -u root ping' or `mysqladmin -u
     root processlist'?

   * What does a client program say when you try to connect to the
     MySQL server? (Try with `mysql', for example.) Does the client
     jam? Do you get any output from the program?

When sending a bug report, you should follow the outline described in
*Note bug-reports::.


File: manual.info,  Node: common-errors,  Next: installation-issues,  Prev: what-is-crashing,  Up: problems

B.1.2 Common Errors When Using MySQL Programs
---------------------------------------------

* Menu:

* error-access-denied::          `Access denied'
* can-not-connect-to-server::    `Can't connect to [local] MySQL server'
* error-lost-connection::        `Lost connection to MySQL server'
* old-client::                   `Client does not support authentication protocol'
* password-too-long::            Password Fails When Entered Interactively
* blocked-host::                 `Host 'HOST_NAME' is blocked'
* too-many-connections::         `Too many connections'
* out-of-memory::                `Out of memory'
* gone-away::                    `MySQL server has gone away'
* packet-too-large::             `Packet too large'
* communication-errors::         Communication Errors and Aborted Connections
* full-table::                   `The table is full'
* cannot-create::                `Can't create/write to file'
* commands-out-of-sync::         `Commands out of sync'
* ignoring-user::                `Ignoring user'
* cannot-find-table::            `Table 'TBL_NAME' doesn't exist'
* cannot-initialize-character-set::  `Can't initialize character set'
* not-enough-file-handles::      `'FILE' Not Found' and Similar Errors
* table-corruption::             Table-Corruption Issues

This section lists some errors that users frequently encounter when
running MySQL programs. Although the problems show up when you try to
run client programs, the solutions to many of the problems involves
changing the configuration of the MySQL server.


File: manual.info,  Node: error-access-denied,  Next: can-not-connect-to-server,  Prev: common-errors,  Up: common-errors

B.1.2.1 `Access denied'
.......................

An `Access denied' error can have many causes. Often the problem is
related to the MySQL accounts that the server allows client programs to
use when connecting.  See *Note access-denied::, and *Note privileges::.


File: manual.info,  Node: can-not-connect-to-server,  Next: error-lost-connection,  Prev: error-access-denied,  Up: common-errors

B.1.2.2 `Can't connect to [local] MySQL server'
...............................................

* Menu:

* can-not-connect-to-server-on-windows::  `Connection to MySQL Server Failing on Windows'

A MySQL client on Unix can connect to the `mysqld' server in two
different ways: By using a Unix socket file to connect through a file
in the filesystem (default `/tmp/mysql.sock'), or by using TCP/IP,
which connects through a port number. A Unix socket file connection is
faster than TCP/IP, but can be used only when connecting to a server on
the same computer. A Unix socket file is used if you don't specify a
hostname or if you specify the special hostname `localhost'.

If the MySQL server is running on Windows, you can connect via TCP/IP.
If the server is started with the `--enable-named-pipe' option, you can
also connect with named pipes if you run the client on the host where
the server is running. The name of the named pipe is `MySQL' by
default. If you don't give a hostname when connecting to `mysqld', a
MySQL client first tries to connect to the named pipe. If that doesn't
work, it connects to the TCP/IP port. You can force the use of named
pipes on Windows by using `.' as the hostname.

The error (2002) `Can't connect to ...' normally means that there is no
MySQL server running on the system or that you are using an incorrect
Unix socket filename or TCP/IP port number when trying to connect to
the server.

The error (2003) `Can't connect to MySQL server on 'SERVER' (10061)'
indicates that the network connection has been refused. You should
check that there is a MySQL server running, that it has network
connections enabled, the network port you specified is the one
configured on the server, and that the TCP/IP port you are using has
not been blocked by a firewall or port blocking service.

Start by checking whether there is a process named `mysqld' running on
your server host. (Use `ps xa | grep mysqld' on Unix or the Task
Manager on Windows.) If there is no such process, you should start the
server. See *Note starting-server::.

If a `mysqld' process is running, you can check it by trying the
following commands. The port number or Unix socket filename might be
different in your setup.  `host_ip' represents the IP number of the
machine where the server is running.

     shell> mysqladmin version
     shell> mysqladmin variables
     shell> mysqladmin -h `hostname` version variables
     shell> mysqladmin -h `hostname` --port=3306 version
     shell> mysqladmin -h host_ip version
     shell> mysqladmin --protocol=SOCKET --socket=/tmp/mysql.sock version

Note the use of backticks rather than forward quotes with the
`hostname' command; these cause the output of `hostname' (that is, the
current hostname) to be substituted into the `mysqladmin' command.  If
you have no `hostname' command or are running on Windows, you can
manually type the hostname of your machine (without backticks)
following the `-h' option. You can also try `-h 127.0.0.1' to connect
with TCP/IP to the local host.

Here are some reasons the `Can't connect to local MySQL server' error
might occur:

   * `mysqld' is not running. Check your operating system's process
     list to ensure the `mysqld' process is present.

   * You're running a MySQL server on Windows with many TCP/IP
     connections to it. If you're experiencing that quite often your
     clients get that error, you can find a workaround here: *Note
     can-not-connect-to-server-on-windows::.

   * You are running on a system that uses MIT-pthreads. If you are
     running on a system that doesn't have native threads, `mysqld'
     uses the MIT-pthreads package.  See *Note which-os::. However, not
     all MIT-pthreads versions support Unix socket files. On a system
     without socket file support, you must always specify the hostname
     explicitly when connecting to the server. Try using this command
     to check the connection to the server:

          shell> mysqladmin -h `hostname` version

   * Someone has removed the Unix socket file that `mysqld' uses
     (`/tmp/mysql.sock' by default). For example, you might have a
     `cron' job that removes old files from the `/tmp' directory. You
     can always run `mysqladmin version' to check whether the Unix
     socket file that `mysqladmin' is trying to use really exists. The
     fix in this case is to change the `cron' job to not remove
     `mysql.sock' or to place the socket file somewhere else. See *Note
     problems-with-mysql-sock::.

   * You have started the `mysqld' server with the
     `--socket=/path/to/socket' option, but forgotten to tell client
     programs the new name of the socket file. If you change the socket
     pathname for the server, you must also notify the MySQL clients.
     You can do this by providing the same `--socket' option when you
     run client programs. You also need to ensure that clients have
     permission to access the `mysql.sock' file. To find out where the
     socket file is, you can do:

          shell> netstat -ln | grep mysql

     See *Note problems-with-mysql-sock::.

   * You are using Linux and one server thread has died (dumped core).
     In this case, you must kill the other `mysqld' threads (for
     example, with `kill' or with the `mysql_zap' script) before you can
     restart the MySQL server. See *Note crashing::.

   * The server or client program might not have the proper access
     privileges for the directory that holds the Unix socket file or
     the socket file itself. In this case, you must either change the
     access privileges for the directory or socket file so that the
     server and clients can access them, or restart `mysqld' with a
     `--socket' option that specifies a socket filename in a directory
     where the server can create it and where client programs can
     access it.

If you get the error message `Can't connect to MySQL server on
some_host', you can try the following things to find out what the
problem is:

   * Check whether the server is running on that host by executing
     `telnet some_host 3306' and pressing the Enter key a couple of
     times. (3306 is the default MySQL port number. Change the value if
     your server is listening to a different port.) If there is a MySQL
     server running and listening to the port, you should get a
     response that includes the server's version number. If you get an
     error such as `telnet: Unable to connect to remote host:
     Connection refused', then there is no server running on the given
     port.

   * If the server is running on the local host, try using `mysqladmin
     -h localhost variables' to connect using the Unix socket file.
     Verify the TCP/IP port number that the server is configured to
     listen to (it is the value of the `port' variable.)

   * Make sure that your `mysqld' server was not started with the
     `--skip-networking' option. If it was, you cannot connect to it
     using TCP/IP.

   * Check to make sure that there is no firewall blocking access to
     MySQL. Your firewall may be configured on the basis of the
     application being executed, or the post number used by MySQL for
     communication (3306 by default).

     Under Linux or Unix, check your IP tables (or similar)
     configuration to ensure that the port has not been blocked.

     Under Windows, applications such as ZoneAlarm and the Windows XP
     personal firewall may need to be configured to allow external
     access to a MySQL server.

   * If you are running under Linux and Security-Enhanced Linux
     (SELinux) is enabled, make sure you have disabled SELinux
     protection for the `mysqld' process.


File: manual.info,  Node: can-not-connect-to-server-on-windows,  Prev: can-not-connect-to-server,  Up: can-not-connect-to-server

B.1.2.3 `Connection to MySQL Server Failing on Windows'
.......................................................

When you're running a MySQL server on Windows with many TCP/IP
connections to it, and you're experiencing that quite often your
clients get a `Can't connect to MySQL server' error, the reason might
be that Windows doesn't allow for enough ephemeral (short-lived) ports
to serve those connections.

By default, Windows allows 5000 ephemeral (short-lived) TCP ports to
the user. After any port is closed it will remain in a `TIME_WAIT'
status for 120 seconds.  This status allows the connection to be reused
at a much lower cost than reinitializing a brand new connection.
However, the port will not be available again until this time expires.

With a small stack of available TCP ports (5000) and a high number of
TCP ports being open and closed over a short period of time along with
the `TIME_WAIT' status you have a good chance for running out of ports.
There are two ways to address this problem:

   * Reduce the number of TCP ports consumed quickly by investigating
     connection pooling or persistent connections where possible

   * Tune some settings in the Windows registry (see below)

* IMPORTANT: The following procedure involves modifying the Windows
registry. Before you modify the registry, make sure to back it up and
make sure that you understand how to restore the registry if a problem
occurs.  For information about how to back up, restore, and edit the
registry, view the following article in the Microsoft Knowledge Base:
`http://support.microsoft.com/kb/256986/EN-US/'.  *

  1. Start Registry Editor (`Regedt32.exe').

  2. Locate the following key in the registry:

          HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters

  3. On the `Edit' menu, click `Add Value', and then add the following
     registry value:

          Value Name: MaxUserPort
          Data Type: REG_DWORD
          Value: 65534

     This sets the number of ephemeral ports available to any user. The
     valid range is between 5000 and 65534 (decimal). The default value
     is 0x1388 (5000 decimal).

  4. On the `Edit' menu, click `Add Value', and then add the following
     registry value:

          Value Name: TcpTimedWaitDelay
          Data Type: REG_DWORD
          Value: 30

     This sets the number of seconds to hold a TCP port connection in
     `TIME_WAIT' state before closing. The valid range is between 0
     (zero) and 300 (decimal). The default value is 0x78 (120 decimal).

  5. Quit Registry Editor.

  6. Reboot the machine.

Note: Undoing the above should be as simple as deleting the registry
entries you've created.


File: manual.info,  Node: error-lost-connection,  Next: old-client,  Prev: can-not-connect-to-server,  Up: common-errors

B.1.2.4 `Lost connection to MySQL server'
.........................................

There are three likely causes for this error message.

Usually it indicates network connectivity trouble and you should check
the condition of your network if this error occurs frequently. If the
error message includes `during query,' this is probably the case you
are experiencing.

Sometimes the `during query' form happens when millions of rows are
being sent as part of one or more queries. If you know that this is
happening, you should try increasing `net_read_timeout' from its
default of 30 seconds to 60 seconds or longer, sufficient for the data
transfer to complete.

More rarely, it can happen when the client is attempting the initial
connection to the server. In this case, if your `connect_timeout' value
is set to only a few seconds, you may be able to resolve the problem by
increasing it to ten seconds, perhaps more if you have a very long
distance or slow connection. You can determine whether you are
experiencing this more uncommon cause by using `SHOW STATUS LIKE
'aborted_connections''. It will increase by one for each initial
connection attempt that the server aborts. You may see `reading
authorization packet' as part of the error message; if so, that also
suggests that this is the solution that you need.

If the cause is none of those just described, you may be experiencing a
problem with `BLOB' values that are larger than `max_allowed_packet',
which can cause this error with some clients. Sometime you may see
`packet too large' as part of the error message, and that confirms that
you need to increase `max_allowed_packet'.


File: manual.info,  Node: old-client,  Next: password-too-long,  Prev: error-lost-connection,  Up: common-errors

B.1.2.5 `Client does not support authentication protocol'
.........................................................

MySQL 5.1 uses an authentication protocol based on a password hashing
algorithm that is incompatible with that used by older (pre-4.1)
clients. If you upgrade the server from 4.0, attempts to connect to it
with an older client may fail with the following message:

     shell> mysql
     Client does not support authentication protocol requested
     by server; consider upgrading MySQL client

To solve this problem, you should use one of the following approaches:

   * Upgrade all client programs to use a 4.1.1 or newer client library.

   * When connecting to the server with a pre-4.1 client program, use
     an account that still has a pre-4.1-style password.

   * Reset the password to pre-4.1 style for each user that needs to
     use a pre-4.1 client program. This can be done using the `SET
     PASSWORD' statement and the `OLD_PASSWORD()' function:

          mysql> SET PASSWORD FOR
              -> 'SOME_USER'@'SOME_HOST' = OLD_PASSWORD('NEWPWD');

     Alternatively, use `UPDATE' and `FLUSH PRIVILEGES':

          mysql> UPDATE mysql.user SET Password = OLD_PASSWORD('NEWPWD')
              -> WHERE Host = 'SOME_HOST' AND User = 'SOME_USER';
          mysql> FLUSH PRIVILEGES;

     Substitute the password you want to use for `NEWPWD' in the
     preceding examples. MySQL cannot tell you what the original
     password was, so you'll need to pick a new one.

   * Tell the server to use the older password hashing algorithm:

       1. Start `mysqld' with the `--old-passwords' option.

       2. Assign an old-format password to each account that has had
          its password updated to the longer 4.1 format. You can
          identify these accounts with the following query:

               mysql> SELECT Host, User, Password FROM mysql.user
                   -> WHERE LENGTH(Password) > 16;

          For each account record displayed by the query, use the
          `Host' and `User' values and assign a password using the
          `OLD_PASSWORD()' function and either `SET PASSWORD' or
          `UPDATE', as described earlier.

*Note*:

In older versions of PHP, the `mysql' extension does not support the
authentication protocol in MySQL 4.1.1 and higher. This is true
regardless of the PHP version being used. If you wish to use the
`mysql' extension with MySQL 4.1 or newer, you may need to follow one
of the options discussed above for configuring MySQL to work with old
clients. The `mysqli' extension (stands for "MySQL, Improved"; added in
PHP 5) is compatible with the improved password hashing employed in
MySQL 4.1 and higher, and no special configuration of MySQL need be
done to use this MySQL client library. For more information about the
`mysqli' extension, see `http://php.net/mysqli'.

It may also be possible to compile the older `mysql' extension against
the new MySQL client library. This is beyond the scope of this Manual;
consult the PHP documentation for more information. You also be able to
obtain assistance with these issues in our MySQL with PHP forum
(http://forums.mysql.com/list.php?52).

For additional background on password hashing and authentication, see
*Note password-hashing::.


File: manual.info,  Node: password-too-long,  Next: blocked-host,  Prev: old-client,  Up: common-errors

B.1.2.6 Password Fails When Entered Interactively
.................................................

MySQL client programs prompt for a password when invoked with a
`--password' or `-p' option that has no following password value:

     shell> mysql -u USER_NAME -p
     Enter password:

On some systems, you may find that your password works when specified
in an option file or on the command line, but not when you enter it
interactively at the `Enter password:' prompt. This occurs when the
library provided by the system to read passwords limits password values
to a small number of characters (typically eight). That is a problem
with the system library, not with MySQL. To work around it, change your
MySQL password to a value that is eight or fewer characters long, or
put your password in an option file.


File: manual.info,  Node: blocked-host,  Next: too-many-connections,  Prev: password-too-long,  Up: common-errors

B.1.2.7 `Host 'HOST_NAME' is blocked'
.....................................

If you get the following error, it means that `mysqld' has received
many connect requests from the host `'HOST_NAME'' that have been
interrupted in the middle:

     Host 'HOST_NAME' is blocked because of many connection errors.
     Unblock with 'mysqladmin flush-hosts'

The number of interrupted connect requests allowed is determined by the
value of the `max_connect_errors' system variable. After
`max_connect_errors' failed requests, `mysqld' assumes that something
is wrong (for example, that someone is trying to break in), and blocks
the host from further connections until you execute a `mysqladmin
flush-hosts' command or issue a `FLUSH HOSTS' statement. See *Note
server-system-variables::.

By default, `mysqld' blocks a host after 10 connection errors. You can
adjust the value by starting the server like this:

     shell> mysqld_safe --max_connect_errors=10000 &

If you get this error message for a given host, you should first verify
that there isn't anything wrong with TCP/IP connections from that host.
If you are having network problems, it does you no good to increase the
value of the `max_connect_errors' variable.


File: manual.info,  Node: too-many-connections,  Next: out-of-memory,  Prev: blocked-host,  Up: common-errors

B.1.2.8 `Too many connections'
..............................

If you get a `Too many connections' error when you try to connect to
the `mysqld' server, this means that all available connections are in
use by other clients.

The number of connections allowed is controlled by the
`max_connections' system variable. Beginning with MySQL 5.1.15, its
default value is 151 to improve performance when MySQL is used with the
Apache Web server.  (Previously, the default was 100.) If you need to
support more connections, you should set a larger value for this
variable.

MySQL Enterprise

Subscribers to the MySQL Enterprise Monitor receive advice on
dynamically configuring the `max_connections' variable -- avoiding
failed connection attempts. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

`mysqld' actually allows `max_connections+1' clients to connect. The
extra connection is reserved for use by accounts that have the `SUPER'
privilege. By granting the `SUPER' privilege to administrators and not
to normal users (who should not need it), an administrator can connect
to the server and use `SHOW PROCESSLIST' to diagnose problems even if
the maximum number of unprivileged clients are connected. See *Note
show-processlist::.

The maximum number of connections MySQL can support depends on the
quality of the thread library on a given platform. Linux or Solaris
should be able to support 500-1000 simultaneous connections, depending
on how much RAM you have and what your clients are doing. Static Linux
binaries provided by MySQL AB can support up to 4000 connections.


File: manual.info,  Node: out-of-memory,  Next: gone-away,  Prev: too-many-connections,  Up: common-errors

B.1.2.9 `Out of memory'
.......................

If you issue a query using the `mysql' client program and receive an
error like the following one, it means that `mysql' does not have
enough memory to store the entire query result:

     mysql: Out of memory at line 42, 'malloc.c'
     mysql: needed 8136 byte (8k), memory in use: 12481367 bytes (12189k)
     ERROR 2008: MySQL client ran out of memory

To remedy the problem, first check whether your query is correct. Is it
reasonable that it should return so many rows?  If not, correct the
query and try again. Otherwise, you can invoke `mysql' with the
`--quick' option. This causes it to use the *Note `mysql_use_result()':
mysql-use-result. C API function to retrieve the result set, which
places less of a load on the client (but more on the server).


File: manual.info,  Node: gone-away,  Next: packet-too-large,  Prev: out-of-memory,  Up: common-errors

B.1.2.10 `MySQL server has gone away'
.....................................

This section also covers the related `Lost connection to server during
query' error.

The most common reason for the `MySQL server has gone away' error is
that the server timed out and closed the connection. In this case, you
normally get one of the following error codes (which one you get is
operating system-dependent):

*Error Code*              *Description*
`CR_SERVER_GONE_ERROR'    The client couldn't send a question to the
                          server.
`CR_SERVER_LOST'          The client didn't get an error when writing to
                          the server, but it didn't get a full answer
                          (or any answer) to the question.

By default, the server closes the connection after eight hours if
nothing has happened. You can change the time limit by setting the
`wait_timeout' variable when you start `mysqld'. See *Note
server-system-variables::.

If you have a script, you just have to issue the query again for the
client to do an automatic reconnection. This assumes that you have
automatic reconnection in the client enabled (which is the default for
the `mysql' command-line client).

Some other common reasons for the `MySQL server has gone away' error
are:

   * You (or the db administrator) has killed the running thread with a
     `KILL' statement or a `mysqladmin kill' command.

   * You tried to run a query after closing the connection to the
     server. This indicates a logic error in the application that
     should be corrected.

   * A client application running on a different host does not have the
     necessary privileges to connect to the MySQL server from that host.

   * You got a timeout from the TCP/IP connection on the client side.
     This may happen if you have been using the commands: *Note
     `mysql_options(..., MYSQL_OPT_READ_TIMEOUT,...)': mysql-options. or
     *Note `mysql_options(..., MYSQL_OPT_WRITE_TIMEOUT,...)':
     mysql-options. In this case increasing the timeout may help solve
     the problem.

   * You have encountered a timeout on the server side and the
     automatic reconnection in the client is disabled (the `reconnect'
     flag in the `MYSQL' structure is equal to 0).

   * You are using a Windows client and the server had dropped the
     connection (probably because `wait_timeout' expired) before the
     command was issued.

     The problem on Windows is that in some cases MySQL doesn't get an
     error from the OS when writing to the TCP/IP connection to the
     server, but instead gets the error when trying to read the answer
     from the connection.

     Prior to MySQL 5.1.8, even if the `reconnect' flag in the `MYSQL'
     structure is equal to 1, MySQL does not automatically reconnect
     and re-issue the query as it doesn't know if the server did get
     the original query or not.

     The solution to this is to either do a *Note `mysql_ping()':
     mysql-ping. on the connection if there has been a long time since
     the last query (this is what `MyODBC' does) or set `wait_timeout'
     on the `mysqld' server so high that it in practice never times out.

   * You can also get these errors if you send a query to the server
     that is incorrect or too large. If `mysqld' receives a packet that
     is too large or out of order, it assumes that something has gone
     wrong with the client and closes the connection. If you need big
     queries (for example, if you are working with big `BLOB' columns),
     you can increase the query limit by setting the server's
     `max_allowed_packet' variable, which has a default value of 1MB.
     You may also need to increase the maximum packet size on the
     client end. More information on setting the packet size is given in
     *Note packet-too-large::.

     An `INSERT' or `REPLACE' statement that inserts a great many rows
     can also cause these sorts of errors. Either one of these
     statements sends a single request to the server irrespective of the
     number of rows to be inserted; thus, you can often avoid the error
     by reducing the number of rows sent per `INSERT' or `REPLACE'.

   * You also get a lost connection if you are sending a packet 16MB or
     larger if your client is older than 4.0.8 and your server is 4.0.8
     and above, or the other way around.

   * It is also possible to see this error if hostname lookups fail
     (for example, if the DNS server on which your server or network
     relies goes down). This is because MySQL is dependent on the host
     system for name resolution, but has no way of knowing whether it
     is working -- from MySQL's point of view the problem is
     indistinguishable from any other network timeout.

     You may also see the `MySQL server has gone away' error if MySQL
     is started with the `--skip-networking' option.

     Another networking issue that can cause this error occurs if the
     MySQL port (default 3306) is blocked by your firewall, thus
     preventing any connections at all to the MySQL server.

   * You can also encounter this error with applications that fork
     child processes, all of which try to use the same connection to
     the MySQL server. This can be avoided by using a separate
     connection for each child process.

   * You have encountered a bug where the server died while executing
     the query.

You can check whether the MySQL server died and restarted by executing
`mysqladmin version' and examining the server's uptime. If the client
connection was broken because `mysqld' crashed and restarted, you
should concentrate on finding the reason for the crash. Start by
checking whether issuing the query again kills the server again. See
*Note crashing::.

You can get more information about the lost connections by starting
mysqld with the `--log-warnings=2' option. This logs some of the
disconnected errors in the `hostname.err' file. See *Note error-log::.

If you want to create a bug report regarding this problem, be sure that
you include the following information:

   * Indicate whether the MySQL server died. You can find information
     about this in the server error log. See *Note crashing::.

   * If a specific query kills `mysqld' and the tables involved were
     checked with `CHECK TABLE' before you ran the query, can you
     provide a reproducible test case? See MySQL Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

   * What is the value of the `wait_timeout' system variable in the
     MySQL server? (`mysqladmin variables' gives you the value of this
     variable.)

   * Have you tried to run `mysqld' with the `--log' option to
     determine whether the problem query appears in the log?

See also *Note communication-errors::, and *Note bug-reports::.


File: manual.info,  Node: packet-too-large,  Next: communication-errors,  Prev: gone-away,  Up: common-errors

B.1.2.11 `Packet too large'
...........................

A communication packet is a single SQL statement sent to the MySQL
server, a single row that is sent to the client, or a binary log event
sent from a master replication server to a slave.

The largest possible packet that can be transmitted to or from a MySQL
5.1 server or client is 1GB.

When a MySQL client or the `mysqld' server receives a packet bigger than
`max_allowed_packet' bytes, it issues a `Packet too large' error and
closes the connection. With some clients, you may also get a `Lost
connection to MySQL server during query' error if the communication
packet is too large.

Both the client and the server have their own `max_allowed_packet'
variable, so if you want to handle big packets, you must increase this
variable both in the client and in the server.

If you are using the `mysql' client program, its default
`max_allowed_packet' variable is 16MB. To set a larger value, start
`mysql' like this:

     shell> mysql --max_allowed_packet=32M

That sets the packet size to 32MB.

The server's default `max_allowed_packet' value is 1MB. You can
increase this if the server needs to handle big queries (for example,
if you are working with big `BLOB' columns). For example, to set the
variable to 16MB, start the server like this:

     shell> mysqld --max_allowed_packet=16M

You can also use an option file to set `max_allowed_packet'. For
example, to set the size for the server to 16MB, add the following
lines in an option file:

     [mysqld]
     max_allowed_packet=16M

It is safe to increase the value of this variable because the extra
memory is allocated only when needed. For example, `mysqld' allocates
more memory only when you issue a long query or when `mysqld' must
return a large result row. The small default value of the variable is a
precaution to catch incorrect packets between the client and server and
also to ensure that you do not run out of memory by using large packets
accidentally.

You can also get strange problems with large packets if you are using
large `BLOB' values but have not given `mysqld' access to enough memory
to handle the query. If you suspect this is the case, try adding
`ulimit -d 256000' to the beginning of the `mysqld_safe' script and
restarting `mysqld'.


File: manual.info,  Node: communication-errors,  Next: full-table,  Prev: packet-too-large,  Up: common-errors

B.1.2.12 Communication Errors and Aborted Connections
.....................................................

The server error log can be a useful source of information about
connection problems. See *Note error-log::. If you start the server
with the `--log-warnings' option, you might find messages like this in
your error log:

     010301 14:38:23  Aborted connection 854 to db: 'users' user: 'josh'

If `Aborted connections' messages appear in the error log, the cause
can be any of the following:

   * The client program did not call *Note `mysql_close()':
     mysql-close. before exiting.

   * The client had been sleeping more than `wait_timeout' or
     `interactive_timeout' seconds without issuing any requests to the
     server. See *Note server-system-variables::.

   * The client program ended abruptly in the middle of a data transfer.

When any of these things happen, the server increments the
`Aborted_clients' status variable.

The server increments the `Aborted_connects' status variable when the
following things happen:

   * A client doesn't have privileges to connect to a database.

   * A client uses an incorrect password.

   * A connection packet doesn't contain the right information.

   * It takes more than `connect_timeout' seconds to get a connect
     packet. See *Note server-system-variables::.

If these kinds of things happen, it might indicate that someone is
trying to break into your server!

MySQL Enterprise

For reasons of security and performance the advisors provided by the
MySQL Enterprise Monitor pay special attention to the
`Aborted_connections' status variable. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

Other reasons for problems with aborted clients or aborted connections:

   * Use of Ethernet protocol with Linux, both half and full duplex.
     Many Linux Ethernet drivers have this bug. You should test for
     this bug by transferring a huge file via FTP between the client
     and server machines. If a transfer goes in burst-pause-burst-pause
     mode, you are experiencing a Linux duplex syndrome. The only
     solution is switching the duplex mode for both your network card
     and hub/switch to either full duplex or to half duplex and testing
     the results to determine the best setting.

   * Some problem with the thread library that causes interrupts on
     reads.

   * Badly configured TCP/IP.

   * Faulty Ethernets, hubs, switches, cables, and so forth.  This can
     be diagnosed properly only by replacing hardware.

   * The `max_allowed_packet' variable value is too small or queries
     require more memory than you have allocated for `mysqld'. See
     *Note packet-too-large::.

See also *Note gone-away::.


File: manual.info,  Node: full-table,  Next: cannot-create,  Prev: communication-errors,  Up: common-errors

B.1.2.13 `The table is full'
............................

The effective maximum table size for MySQL databases is usually
determined by operating system constraints on file sizes, not by MySQL
internal limits. The following table lists some examples of operating
system file-size limits. This is only a rough guide and is not intended
to be definitive. For the most up-to-date information, be sure to check
the documentation specific to your operating system.

*Operating System*     *File-size Limit*
Win32 w/ FAT/FAT32     2GB/4GB
Win32 w/ NTFS          2TB (possibly larger)
Linux 2.2-Intel 32-bit 2GB (LFS: 4GB)
Linux 2.4+             (using ext3 filesystem) 4TB
Solaris 9/10           16TB
MacOS X w/ HFS+        2TB
NetWare w/NSS          8TB
filesystem             

Windows users, please note that FAT and VFAT (FAT32) are _not_
considered suitable for production use with MySQL. Use NTFS instead.

On Linux 2.2, you can get `MyISAM' tables larger than 2GB in size by
using the Large File Support (LFS) patch for the ext2 filesystem. Most
current Linux distributions are based on kernel 2.4 or higher and
include all the required LFS patches. On Linux 2.4, patches also exist
for ReiserFS to get support for big files (up to 2TB). With JFS and
XFS, petabyte and larger files are possible on Linux.

For a detailed overview about LFS in Linux, have a look at Andreas
Jaeger's `Large File Support in Linux' page at
`http://www.suse.de/~aj/linux_lfs.html'.

If you do encounter a full-table error, there are several reasons why
it might have occurred:

   * The `InnoDB' storage engine maintains `InnoDB' tables within a
     tablespace that can be created from several files. This allows a
     table to exceed the maximum individual file size. The tablespace
     can include raw disk partitions, which allows extremely large
     tables. The maximum tablespace size is 64TB.

     If you are using `InnoDB' tables and run out of room in the
     `InnoDB' tablespace.  In this case, the solution is to extend the
     `InnoDB' tablespace. See *Note adding-and-removing::.

   * You are using `MyISAM' tables on an operating system that supports
     files only up to 2GB in size and you have hit this limit for the
     data file or index file.

   * You are using a `MyISAM' table and the space required for the
     table exceeds what is allowed by the internal pointer size.
     `MyISAM' allows data and index files to grow up to 256TB by
     default, but this limit can be changed up to the maximum allowable
     size of 65,536TB (256^7 - 1 bytes).

     If you need a `MyISAM' table that is larger than the default limit
     and your operating system supports large files, the `CREATE TABLE'
     statement supports `AVG_ROW_LENGTH' and `MAX_ROWS' options. See
     *Note create-table::. The server uses these options to determine
     how large a table to allow.

     If the pointer size is too small for an existing table, you can
     change the options with `ALTER TABLE' to increase a table's
     maximum allowable size. See *Note alter-table::.

          ALTER TABLE TBL_NAME MAX_ROWS=1000000000 AVG_ROW_LENGTH=NNN;

     You have to specify `AVG_ROW_LENGTH' only for tables with `BLOB' or
     `TEXT' columns; in this case, MySQL can't optimize the space
     required based only on the number of rows.

     To change the default size limit for `MyISAM' tables, set the
     `myisam_data_pointer_size', which sets the number of bytes used
     for internal row pointers. The value is used to set the pointer
     size for new tables if you do not specify the `MAX_ROWS' option.
     The value of `myisam_data_pointer_size' can be from 2 to 7. A
     value of 4 allows tables up to 4GB; a value of 6 allows tables up
     to 256TB.

     You can check the maximum data and index sizes by using this
     statement:

          SHOW TABLE STATUS FROM DB_NAME LIKE 'TBL_NAME';

     You also can use `myisamchk -dv /path/to/table-index-file'. See
     *Note show::, or *Note myisamchk::.

     Other ways to work around file-size limits for `MyISAM' tables are
     as follows:

        * If your large table is read only, you can use `myisampack' to
          compress it.  `myisampack' usually compresses a table by at
          least 50%, so you can have, in effect, much bigger tables.
          `myisampack' also can merge multiple tables into a single
          table. See *Note myisampack::.

        * MySQL includes a `MERGE' library that allows you to handle a
          collection of `MyISAM' tables that have identical structure
          as a single `MERGE' table.  See *Note merge-storage-engine::.

   * You are using the `NDB' storage engine, in which case you need to
     increase the values for the `DataMemory' and `IndexMemory'
     configuration parameters in your `config.ini' file. See *Note
     mysql-cluster-config-params-ndbd::.

   * You are using the `MEMORY' (`HEAP') storage engine; in this case
     you need to increase the value of the `max_heap_table_size' system
     variable.  See *Note server-system-variables::.


File: manual.info,  Node: cannot-create,  Next: commands-out-of-sync,  Prev: full-table,  Up: common-errors

B.1.2.14 `Can't create/write to file'
.....................................

If you get an error of the following type for some queries, it means
that MySQL cannot create a temporary file for the result set in the
temporary directory:

     Can't create/write to file '\\sqla3fe_0.ism'.

The preceding error is a typical message for Windows; the Unix message
is similar.

One fix is to start `mysqld' with the `--tmpdir' option or to add the
option to the `[mysqld]' section of your option file. For example, to
specify a directory of `C:\temp', use these lines:

     [mysqld]
     tmpdir=C:/temp

The `C:\temp' directory must exist and have sufficient space for the
MySQL server to write to. See *Note option-files::.

Another cause of this error can be permissions issues. Make sure that
the MySQL server can write to the `tmpdir' directory.

Check also the error code that you get with `perror'. One reason the
server cannot write to a table is that the filesystem is full:

     shell> perror 28
     OS error code  28:  No space left on device

If you get an error of the following type during startup, it indicates
that the filesystem and/or directory used for storing data files is
write protected. Providing the write error is to a test file, This
error is not serious and can be safely ignored.

     Can't create test file /usr/local/mysql/data/master.lower-test


File: manual.info,  Node: commands-out-of-sync,  Next: ignoring-user,  Prev: cannot-create,  Up: common-errors

B.1.2.15 `Commands out of sync'
...............................

If you get `Commands out of sync; you can't run this command now' in
your client code, you are calling client functions in the wrong order.

This can happen, for example, if you are using *Note
`mysql_use_result()': mysql-use-result. and try to execute a new query
before you have called *Note `mysql_free_result()': mysql-free-result.
It can also happen if you try to execute two queries that return data
without calling *Note `mysql_use_result()': mysql-use-result. or *Note
`mysql_store_result()': mysql-store-result. in between.


File: manual.info,  Node: ignoring-user,  Next: cannot-find-table,  Prev: commands-out-of-sync,  Up: common-errors

B.1.2.16 `Ignoring user'
........................

If you get the following error, it means that when `mysqld' was started
or when it reloaded the grant tables, it found an account in the `user'
table that had an invalid password.

`Found wrong password for user 'SOME_USER'@'SOME_HOST'; ignoring user'

As a result, the account is simply ignored by the permission system.

The following list indicates possible causes of and fixes for this
problem:

   * You may be running a new version of `mysqld' with an old `user'
     table. You can check this by executing `mysqlshow mysql user' to
     see whether the `Password' column is shorter than 16 characters.
     If so, you can correct this condition by running the
     `scripts/add_long_password' script.

   * The account has an old password (eight characters long).  Update
     the account in the `user' table to have a new password.

   * You have specified a password in the `user' table without using the
     `PASSWORD()' function. Use `mysql' to update the account in the
     `user' table with a new password, making sure to use the
     `PASSWORD()' function:

          mysql> UPDATE user SET Password=PASSWORD('NEWPWD')
              -> WHERE User='SOME_USER' AND Host='SOME_HOST';


File: manual.info,  Node: cannot-find-table,  Next: cannot-initialize-character-set,  Prev: ignoring-user,  Up: common-errors

B.1.2.17 `Table 'TBL_NAME' doesn't exist'
.........................................

If you get either of the following errors, it usually means that no
table exists in the default database with the given name:

     Table 'TBL_NAME' doesn't exist
     Can't find file: 'TBL_NAME' (errno: 2)

In some cases, it may be that the table does exist but that you are
referring to it incorrectly:

   * Because MySQL uses directories and files to store databases and
     tables, database and table names are case sensitive if they are
     located on a filesystem that has case-sensitive filenames.

   * Even for filesystems that are not case sensitive, such as on
     Windows, all references to a given table within a query must use
     the same lettercase.

You can check which tables are in the default database with `SHOW
TABLES'. See *Note show::.


File: manual.info,  Node: cannot-initialize-character-set,  Next: not-enough-file-handles,  Prev: cannot-find-table,  Up: common-errors

B.1.2.18 `Can't initialize character set'
.........................................

You might see an error like this if you have character set problems:

     MySQL Connection Failed: Can't initialize character set CHARSET_NAME

This error can have any of the following causes:

   * The character set is a multi-byte character set and you have no
     support for the character set in the client. In this case, you
     need to recompile the client by running `configure' with the
     `--with-charset=CHARSET_NAME' or
     `--with-extra-charsets=CHARSET_NAME' option. See *Note
     configure-options::.

     All standard MySQL binaries are compiled with
     `--with-extra-character-sets=complex', which enables support for
     all multi-byte character sets.  See *Note charset-configuration::.

   * The character set is a simple character set that is not compiled
     into `mysqld', and the character set definition files are not in
     the place where the client expects to find them.

     In this case, you need to use one of the following methods to
     solve the problem:

        * Recompile the client with support for the character set. See
          *Note configure-options::.

        * Specify to the client the directory where the character set
          definition files are located. For many clients, you can do
          this with the `--character-sets-dir' option.

        * Copy the character definition files to the path where the
          client expects them to be.


File: manual.info,  Node: not-enough-file-handles,  Next: table-corruption,  Prev: cannot-initialize-character-set,  Up: common-errors

B.1.2.19 `'FILE' Not Found' and Similar Errors
..............................................

If you get `ERROR '...' not found (errno: 23)', `Can't open file: ...
(errno: 24)', or any other error with `errno 23' or `errno 24' from
MySQL, it means that you haven't allocated enough file descriptors for
the MySQL server. You can use the `perror' utility to get a description
of what the error number means:

     shell> perror 23
     OS error code  23:  File table overflow
     shell> perror 24
     OS error code  24:  Too many open files
     shell> perror 11
     OS error code  11:  Resource temporarily unavailable

The problem here is that `mysqld' is trying to keep open too many files
simultaneously. You can either tell `mysqld' not to open so many files
at once or increase the number of file descriptors available to
`mysqld'.

To tell `mysqld' to keep open fewer files at a time, you can make the
table cache smaller by reducing the value of the `table_open_cache'
system variable (the default value is 64). Reducing the value of
`max_connections' also reduces the number of open files (the default
value is 100).

To change the number of file descriptors available to `mysqld', you can
use the `--open-files-limit' option to `mysqld_safe' or set the
`open_files_limit' system variable. See *Note
server-system-variables::. The easiest way to set these values is to
add an option to your option file. See *Note option-files::. If you
have an old version of `mysqld' that doesn't support setting the open
files limit, you can edit the `mysqld_safe' script. There is a
commented-out line `ulimit -n 256' in the script. You can remove the
``#'' character to uncomment this line, and change the number `256' to
set the number of file descriptors to be made available to `mysqld'.

`--open-files-limit' and `ulimit' can increase the number of file
descriptors, but only up to the limit imposed by the operating system.
There is also a `hard' limit that can be overridden only if you start
`mysqld_safe' or `mysqld' as `root' (just remember that you also need
to start the server with the `--user' option in this case so that it
does not continue to run as `root' after it starts up). If you need to
increase the operating system limit on the number of file descriptors
available to each process, consult the documentation for your system.

*Note*:

If you run the `tcsh' shell, `ulimit' does not work!  `tcsh' also
reports incorrect values when you ask for the current limits. In this
case, you should start `mysqld_safe' using `sh'.


File: manual.info,  Node: table-corruption,  Prev: not-enough-file-handles,  Up: common-errors

B.1.2.20 Table-Corruption Issues
................................

If you have started `mysqld' with `--myisam-recover', MySQL
automatically checks and tries to repair `MyISAM' tables if they are
marked as 'not closed properly' or 'crashed'. If this happens, MySQL
writes an entry in the `hostname.err' file `'Warning: Checking table
...'' which is followed by `Warning: Repairing table' if the table needs
to be repaired. If you get a lot of these errors, without `mysqld'
having died unexpectedly just before, then something is wrong and needs
to be investigated further.

See also *Note server-options::, and *Note reproducible-test-case::.


File: manual.info,  Node: installation-issues,  Next: administration-issues,  Prev: common-errors,  Up: problems

B.1.3 Installation-Related Issues
---------------------------------

* Menu:

* link-errors::                  Problems Linking to the MySQL Client Library
* file-permissions::             Problems with File Permissions


File: manual.info,  Node: link-errors,  Next: file-permissions,  Prev: installation-issues,  Up: installation-issues

B.1.3.1 Problems Linking to the MySQL Client Library
....................................................

When you are linking an application program to use the MySQL client
library, you might get undefined reference errors for symbols that
start with `mysql_', such as those shown here:

     /tmp/ccFKsdPa.o: In function `main':
     /tmp/ccFKsdPa.o(.text+0xb): undefined reference to `mysql_init'
     /tmp/ccFKsdPa.o(.text+0x31): undefined reference to `mysql_real_connect'
     /tmp/ccFKsdPa.o(.text+0x57): undefined reference to `mysql_real_connect'
     /tmp/ccFKsdPa.o(.text+0x69): undefined reference to `mysql_error'
     /tmp/ccFKsdPa.o(.text+0x9a): undefined reference to `mysql_close'

You should be able to solve this problem by adding `-Ldir_path
-lmysqlclient' at the end of your link command, where `dir_path'
represents the pathname of the directory where the client library is
located.  To determine the correct directory, try this command:

     shell> mysql_config --libs

The output from `mysql_config' might indicate other libraries that
should be specified on the link command as well.

If you get `undefined reference' errors for the `uncompress' or
`compress' function, add `-lz' to the end of your link command and try
again.

If you get `undefined reference' errors for a function that should
exist on your system, such as `connect', check the manual page for the
function in question to determine which libraries you should add to the
link command.

You might get `undefined reference' errors such as the following for
functions that don't exist on your system:

     mf_format.o(.text+0x201): undefined reference to `__lxstat'

This usually means that your MySQL client library was compiled on a
system that is not 100% compatible with yours. In this case, you should
download the latest MySQL source distribution and compile MySQL
yourself. See *Note installing-source::.

You might get undefined reference errors at runtime when you try to
execute a MySQL program. If these errors specify symbols that start
with `mysql_' or indicate that the `mysqlclient' library can't be
found, it means that your system can't find the shared
`libmysqlclient.so' library. The fix for this is to tell your system to
search for shared libraries where the library is located. Use whichever
of the following methods is appropriate for your system:

   * Add the path to the directory where `libmysqlclient.so' is located
     to the `LD_LIBRARY_PATH' environment variable.

   * Add the path to the directory where `libmysqlclient.so' is located
     to the `LD_LIBRARY' environment variable.

   * Copy `libmysqlclient.so' to some directory that is searched by
     your system, such as `/lib', and update the shared library
     information by executing `ldconfig'.

Another way to solve this problem is by linking your program statically
with the `-static' option, or by removing the dynamic MySQL libraries
before linking your code.  Before trying the second method, you should
be sure that no other programs are using the dynamic libraries.


File: manual.info,  Node: file-permissions,  Prev: link-errors,  Up: installation-issues

B.1.3.2 Problems with File Permissions
......................................

If you have problems with file permissions, the `UMASK' environment
variable might be set incorrectly when `mysqld' starts. For example,
MySQL might issue the following error message when you create a table:

     ERROR: Can't find file: 'path/with/filename.frm' (Errcode: 13)

The default `UMASK' value is `0660'. You can change this behavior by
starting `mysqld_safe' as follows:

     shell> UMASK=384  # = 600 in octal
     shell> export UMASK
     shell> mysqld_safe &

By default, MySQL creates database directories with an access
permission value of `0700'. You can modify this behavior by setting the
`UMASK_DIR' variable. If you set its value, new directories are created
with the combined `UMASK' and `UMASK_DIR' values. For example, if you
want to give group access to all new directories, you can do this:

     shell> UMASK_DIR=504  # = 770 in octal
     shell> export UMASK_DIR
     shell> mysqld_safe &

In MySQL 3.23.25 and above, MySQL assumes that the value for `UMASK'
and `UMASK_DIR' is in octal if it starts with a zero.

See *Note environment-variables::.


File: manual.info,  Node: administration-issues,  Next: query-issues,  Prev: installation-issues,  Up: problems

B.1.4 Administration-Related Issues
-----------------------------------

* Menu:

* resetting-permissions::        How to Reset the Root Password
* crashing::                     What to Do If MySQL Keeps Crashing
* full-disk::                    How MySQL Handles a Full Disk
* temporary-files::              Where MySQL Stores Temporary Files
* problems-with-mysql-sock::     How to Protect or Change the MySQL Unix Socket File
* timezone-problems::            Time Zone Problems


File: manual.info,  Node: resetting-permissions,  Next: crashing,  Prev: administration-issues,  Up: administration-issues

B.1.4.1 How to Reset the Root Password
......................................

* Menu:

* resetting-permissions-windows::  Resetting the Root Password on Windows Systems
* resetting-permissions-unix::   Resetting the Root Password on Unix Systems

If you have never set a `root' password for MySQL, the server does not
require a password at all for connecting as `root'. However, it is
recommended to set a password for each account. See *Note
security-guidelines::.

If you set a `root' password previously, but have forgotten what it
was, you can set a new password. The next two sections show procedures
for Windows and Unix systems, respectively.


File: manual.info,  Node: resetting-permissions-windows,  Next: resetting-permissions-unix,  Prev: resetting-permissions,  Up: resetting-permissions

B.1.4.2 Resetting the Root Password on Windows Systems
......................................................

Use the following procedure for resetting the password for any MySQL
`root' accounts on Windows:

  1. Log on to your system as Administrator.

  2. Stop the MySQL server if it is running. For a server that is
     running as a Windows service, go to the Services manager:

          Start Menu -> Control Panel -> Administrative Tools -> Services

     Then find the MySQL service in the list, and stop it.

     If your server is not running as a service, you may need to use
     the Task Manager to force it to stop.

  3. Create a text file and place the following statements in it.
     Replace the password with the password that you want to use.

          UPDATE mysql.user SET Password=PASSWORD('MyNewPass') WHERE User='root';
          FLUSH PRIVILEGES;

     The `UPDATE' and `FLUSH' statements each must be written on a
     single line. The `UPDATE' statement resets the password for all
     existing `root' accounts, and the `FLUSH' statement tells the
     server to reload the grant tables into memory.

  4. Save the file. For this example, the file will be named
     `C:\mysql-init.txt'.

  5. Open a console window to get to the command prompt:

          Start Menu -> Run -> cmd

  6. Start the MySQL server with the special `--init-file' option:

          C:\> C:\mysql\bin\mysqld --init-file=C:\mysql-init.txt

     If you installed MySQL to a location other than `C:\mysql', adjust
     the command accordingly.

     The server executes the contents of the file named by the
     `--init-file' option at startup, changing each `root' account
     password.

     You can also add the `--console' option to the command if you want
     server output to appear in the console window rather than in a log
     file.

     If you installed MySQL using the MySQL Installation Wizard, you
     may need to specify a `--defaults-file' option:

          C:\> "C:\Program Files\MySQL\MySQL Server 5.1\bin\mysqld.exe"
                   --defaults-file="C:\Program Files\MySQL\MySQL Server 5.1\my.ini"
                   --init-file=C:\mysql-init.txt

     The appropriate `--defaults-file' setting can be found using the
     Services Manager:

          Start Menu -> Control Panel -> Administrative Tools -> Services

     Find the MySQL service in the list, right-click on it, and choose
     the `Properties' option. The `Path to executable' field contains
     the `--defaults-file' setting.

  7. After the server has started successfully, delete
     `C:\mysql-init.txt'.

  8. Stop the MySQL server, then restart it in normal mode again. If
     you run the server as a service, start it from the Windows
     Services window. If you start the server manually, use whatever
     command you normally use.

You should now be able to connect to MySQL as `root' using the new
password.


File: manual.info,  Node: resetting-permissions-unix,  Prev: resetting-permissions-windows,  Up: resetting-permissions

B.1.4.3 Resetting the Root Password on Unix Systems
...................................................

MySQL Enterprise

For expert advice on security-related issues, subscribe to the MySQL
Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

Use the following procedure for resetting the password for any MySQL
`root' accounts on Unix. The instructions assume that you will start
the server so that it runs using the Unix login account that you
normally use for running the server. For example, if you run the server
using the `mysql' login account, you should log in as `mysql' before
using the instructions. (Alternatively, you can log in as `root', but
in this case you _must_ start start `mysqld' with the `--user=mysql'
option. If you start the server as `root' without using `--user=mysql',
the server may create `root'-owned files in the data directory, such as
log files, and these may cause permission-related problems for future
server startups. If that happens, you will need to either change the
ownership of the files to `mysql' or remove them.)

  1. Log on to your system as the Unix `mysql' user that the `mysqld'
     server runs as.

  2. Locate the `.pid' file that contains the server's process ID. The
     exact location and name of this file depend on your distribution,
     hostname, and configuration. Common locations are
     `/var/lib/mysql/', `/var/run/mysqld/', and
     `/usr/local/mysql/data/'. Generally, the filename has an extension
     of `.pid' and begins with either `mysqld' or your system's
     hostname.

     You can stop the MySQL server by sending a normal `kill' (not
     `kill -9') to the `mysqld' process, using the pathname of the
     `.pid' file in the following command:

          shell> kill `cat /mysql-data-directory/host_name.pid`

     Note the use of backticks rather than forward quotes with the
     `cat' command; these cause the output of `cat' to be substituted
     into the `kill' command.

  3. Create a text file and place the following statements in it.
     Replace the password with the password that you want to use.

          UPDATE mysql.user SET Password=PASSWORD('MyNewPass') WHERE User='root';
          FLUSH PRIVILEGES;

     The `UPDATE' and `FLUSH' statements each must be written on a
     single line. The `UPDATE' statement resets the password for all
     existing `root' accounts, and the `FLUSH' statement tells the
     server to reload the grant tables into memory.

  4. Save the file. For this example, the file will be named
     `/home/me/mysql-init'. The file contains the password, so it
     should not be saved where it can be read by other users.

  5. Start the MySQL server with the special `--init-file' option:

          shell> mysqld_safe --init-file=/home/me/mysql-init &

     The server executes the contents of the file named by the
     `--init-file' option at startup, changing each `root' account
     password.

  6. After the server has started successfully, delete
     `/home/me/mysql-init'.

You should now be able to connect to MySQL as `root' using the new
password.

Alternatively, on any platform, you can set the new password using the
`mysql' client (but this approach is less secure):

  1. Stop `mysqld' and restart it with the `--skip-grant-tables' option.

  2. Connect to the `mysqld' server with this command:

          shell> mysql

  3. Issue the following statements in the `mysql' client. Replace the
     password with the password that you want to use.

          mysql> UPDATE mysql.user SET Password=PASSWORD('MyNewPass')
              ->                   WHERE User='root';
          mysql> FLUSH PRIVILEGES;

You should now be able to connect to MySQL as `root' using the new
password.


File: manual.info,  Node: crashing,  Next: full-disk,  Prev: resetting-permissions,  Up: administration-issues

B.1.4.4 What to Do If MySQL Keeps Crashing
..........................................

Each MySQL version is tested on many platforms before it is released.
This doesn't mean that there are no bugs in MySQL, but if there are
bugs, they should be very few and can be hard to find. If you have a
problem, it always helps if you try to find out exactly what crashes
your system, because you have a much better chance of getting the
problem fixed quickly.

First, you should try to find out whether the problem is that the
`mysqld' server dies or whether your problem has to do with your
client. You can check how long your `mysqld' server has been up by
executing `mysqladmin version'. If `mysqld' has died and restarted, you
may find the reason by looking in the server's error log. See *Note
error-log::.

On some systems, you can find in the error log a stack trace of where
`mysqld' died that you can resolve with the `resolve_stack_dump'
program. See MySQL Internals: Porting
(http://forge.mysql.com/wiki/MySQL_Internals_Porting). Note that the
variable values written in the error log may not always be 100% correct.

Many server crashes are caused by corrupted data files or index files.
MySQL updates the files on disk with the `write()' system call after
every SQL statement and before the client is notified about the result.
(This is not true if you are running with `--delay-key-write', in which
case data files are written but not index files.) This means that data
file contents are safe even if `mysqld' crashes, because the operating
system ensures that the unflushed data is written to disk. You can
force MySQL to flush everything to disk after every SQL statement by
starting `mysqld' with the `--flush' option.

The preceding means that normally you should not get corrupted tables
unless one of the following happens:

   * The MySQL server or the server host was killed in the middle of an
     update.

   * You have found a bug in `mysqld' that caused it to die in the
     middle of an update.

   * Some external program is manipulating data files or index files at
     the same time as `mysqld' without locking the table properly.

   * You are running many `mysqld' servers using the same data
     directory on a system that doesn't support good filesystem locks
     (normally handled by the `lockd' lock manager), or you are running
     multiple servers with external locking disabled.

   * You have a crashed data file or index file that contains very
     corrupt data that confused `mysqld'.

   * You have found a bug in the data storage code. This isn't likely,
     but it's at least possible. In this case, you can try to change
     the storage engine to another engine by using `ALTER TABLE' on a
     repaired copy of the table.

Because it is very difficult to know why something is crashing, first
try to check whether things that work for others crash for you. Please
try the following things:

   * Stop the `mysqld' server with `mysqladmin shutdown', run
     `myisamchk --silent --force */*.MYI' from the data directory to
     check all `MyISAM' tables, and restart `mysqld'. This ensures that
     you are running from a clean state. See *Note
     server-administration::.

   * Start `mysqld' with the `--log' option and try to determine from
     the information written to the log whether some specific query
     kills the server. About 95% of all bugs are related to a
     particular query. Normally, this is one of the last queries in the
     log file just before the server restarts.  See *Note query-log::.
     If you can repeatedly kill MySQL with a specific query, even when
     you have checked all tables just before issuing it, then you have
     been able to locate the bug and should submit a bug report for it.
     See *Note bug-reports::.

   * Try to make a test case that we can use to repeat the problem. See
     MySQL Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

   * Try running the tests in the `mysql-test' directory and the MySQL
     benchmarks. See *Note mysql-test-suite::. They should test MySQL
     rather well. You can also add code to the benchmarks that
     simulates your application. The benchmarks can be found in the
     `sql-bench' directory in a source distribution or, for a binary
     distribution, in the `sql-bench' directory under your MySQL
     installation directory.

   * Try the `fork_big.pl' script. (It is located in the `tests'
     directory of source distributions.)

   * If you configure MySQL for debugging, it is much easier to gather
     information about possible errors if something goes wrong.
     Configuring MySQL for debugging causes a safe memory allocator to
     be included that can find some errors.  It also provides a lot of
     output about what is happening.  Reconfigure MySQL with the
     `--with-debug' or `--with-debug=full' option to `configure' and
     then recompile. See MySQL Internals: Porting
     (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

   * Make sure that you have applied the latest patches for your
     operating system.

   * Use the `--skip-external-locking' option to `mysqld'. On some
     systems, the `lockd' lock manager does not work properly; the
     `--skip-external-locking' option tells `mysqld' not to use external
     locking. (This means that you cannot run two `mysqld' servers on
     the same data directory and that you must be careful if you use
     `myisamchk'. Nevertheless, it may be instructive to try the option
     as a test.)

   * Have you tried `mysqladmin -u root processlist' when `mysqld'
     appears to be running but not responding? Sometimes `mysqld' is
     not comatose even though you might think so. The problem may be
     that all connections are in use, or there may be some internal
     lock problem.  `mysqladmin -u root processlist' usually is able to
     make a connection even in these cases, and can provide useful
     information about the current number of connections and their
     status.

   * Run the command `mysqladmin -i 5 status' or `mysqladmin -i 5 -r
     status' in a separate window to produce statistics while you run
     your other queries.

   * Try the following:

       1. Start `mysqld' from `gdb' (or another debugger). See MySQL
          Internals: Porting
          (http://forge.mysql.com/wiki/MySQL_Internals_Porting).

       2. Run your test scripts.

       3. Print the backtrace and the local variables at the three
          lowest levels. In `gdb', you can do this with the following
          commands when `mysqld' has crashed inside `gdb':

               backtrace
               info local
               up
               info local
               up
               info local

          With `gdb', you can also examine which threads exist with
          `info threads' and switch to a specific thread with `thread
          N', where N is the thread ID.

   * Try to simulate your application with a Perl script to force MySQL
     to crash or misbehave.

   * Send a normal bug report. See *Note bug-reports::. Be even more
     detailed than usual. Because MySQL works for many people, it may
     be that the crash results from something that exists only on your
     computer (for example, an error that is related to your particular
     system libraries).

   * If you have a problem with tables containing dynamic-length rows
     and you are using only `VARCHAR' columns (not `BLOB' or `TEXT'
     columns), you can try to change all `VARCHAR' to `CHAR' with
     `ALTER TABLE'. This forces MySQL to use fixed-size rows.
     Fixed-size rows take a little extra space, but are much more
     tolerant to corruption.

     The current dynamic row code has been in use at MySQL AB for
     several years with very few problems, but dynamic-length rows are
     by nature more prone to errors, so it may be a good idea to try
     this strategy to see whether it helps.

   * Do not rule out your server hardware when diagnosing problems.
     Defective hardware can be the cause of data corruption. Particular
     attention should be paid to both RAMS and hard-drives when
     troubleshooting hardware.


File: manual.info,  Node: full-disk,  Next: temporary-files,  Prev: crashing,  Up: administration-issues

B.1.4.5 How MySQL Handles a Full Disk
.....................................

This section describes how MySQL responds to disk-full errors (such as
`no space left on device'), and to quota-exceeded errors (such as
`write failed' or `user block limit reached').

This section is relevant for writes to `MyISAM' tables. It also applies
for writes to binary log files and binary log index file, except that
references to `row' and `record' should be understood to mean `event.'

When a disk-full condition occurs, MySQL does the following:

   * It checks once every minute to see whether there is enough space
     to write the current row. If there is enough space, it continues
     as if nothing had happened.

   * Every 10 minutes it writes an entry to the log file, warning about
     the disk-full condition.

To alleviate the problem, you can take the following actions:

   * To continue, you only have to free enough disk space to insert all
     records.

   * To abort the thread, you must use `mysqladmin kill'. The thread is
     aborted the next time it checks the disk (in one minute).

   * Other threads might be waiting for the table that caused the
     disk-full condition. If you have several `locked' threads, killing
     the one thread that is waiting on the disk-full condition allows
     the other threads to continue.

Exceptions to the preceding behavior are when you use `REPAIR TABLE' or
`OPTIMIZE TABLE' or when the indexes are created in a batch after `LOAD
DATA INFILE' or after an `ALTER TABLE' statement. All of these
statements may create large temporary files that, if left to
themselves, would cause big problems for the rest of the system. If the
disk becomes full while MySQL is doing any of these operations, it
removes the big temporary files and mark the table as crashed. The
exception is that for `ALTER TABLE', the old table is left unchanged.

MySQL Enterprise

For early notification of possible problems with your MySQL
configuration subscribe to the MySQL Enterprise Monitor. For more
information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: temporary-files,  Next: problems-with-mysql-sock,  Prev: full-disk,  Up: administration-issues

B.1.4.6 Where MySQL Stores Temporary Files
..........................................

MySQL uses the value of the `TMPDIR' environment variable as the
pathname of the directory in which to store temporary files. If you
don't have `TMPDIR' set, MySQL uses the system default, which is
normally `/tmp', `/var/tmp', or `/usr/tmp'. If the filesystem containing
your temporary file directory is too small, you can use the `--tmpdir'
option to `mysqld' to specify a directory in a filesystem where you
have enough space.

In MySQL 5.1, the `--tmpdir' option can be set to a list of several
paths that are used in round-robin fashion. Paths should be separated
by colon characters (``:'') on Unix and semicolon characters (``;'') on
Windows, NetWare, and OS/2.

*Note*:

To spread the load effectively, these paths should be located on
different _physical_ disks, not different partitions of the same disk.

If the MySQL server is acting as a replication slave, you should not
set `--tmpdir' to point to a directory on a memory-based filesystem or
to a directory that is cleared when the server host restarts. A
replication slave needs some of its temporary files to survive a
machine restart so that it can replicate temporary tables or `LOAD DATA
INFILE' operations. If files in the temporary file directory are lost
when the server restarts, replication fails.

MySQL creates all temporary files as hidden files. This ensures that
the temporary files are removed if `mysqld' is terminated. The
disadvantage of using hidden files is that you do not see a big
temporary file that fills up the filesystem in which the temporary file
directory is located.

MySQL Enterprise

Advisors provided by the MySQL Enterprise Monitor automatically detect
excessive temporary table storage to disk. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.

When sorting (`ORDER BY' or `GROUP BY'), MySQL normally uses one or two
temporary files.  The maximum disk space required is determined by the
following expression:

     (length of what is sorted + sizeof(row pointer))
     * number of matched rows
     * 2

The row pointer size is usually four bytes, but may grow in the future
for really big tables.

For some `SELECT' queries, MySQL also creates temporary SQL tables.
These are not hidden and have names of the form `SQL_*'.

`ALTER TABLE' creates a temporary table in the same directory as the
original table.


File: manual.info,  Node: problems-with-mysql-sock,  Next: timezone-problems,  Prev: temporary-files,  Up: administration-issues

B.1.4.7 How to Protect or Change the MySQL Unix Socket File
...........................................................

The default location for the Unix socket file that the server uses for
communication with local clients is `/tmp/mysql.sock'. (For some
distribution formats, the directory might be different, such as
`/var/lib/mysql' for RPMs.)

On some versions of Unix, anyone can delete files in the `/tmp'
directory or other similar directories used for temporary files. If the
socket file is located in such a directory on your system, this might
cause problems.

On most versions of Unix, you can protect your `/tmp' directory so that
files can be deleted only by their owners or the superuser (`root'). To
do this, set the `sticky' bit on the `/tmp' directory by logging in as
`root' and using the following command:

     shell> chmod +t /tmp

You can check whether the `sticky' bit is set by executing `ls -ld
/tmp'. If the last permission character is `t', the bit is set.

Another approach is to change the place where the server creates the
Unix socket file. If you do this, you should also let client programs
know the new location of the file. You can specify the file location in
several ways:

   * Specify the path in a global or local option file. For example,
     put the following lines in `/etc/my.cnf':

          [mysqld]
          socket=/path/to/socket

          [client]
          socket=/path/to/socket

     See *Note option-files::.

   * Specify a `--socket' option on the command line to `mysqld_safe'
     and when you run client programs.

   * Set the `MYSQL_UNIX_PORT' environment variable to the path of the
     Unix socket file.

   * Recompile MySQL from source to use a different default Unix socket
     file location. Define the path to the file with the
     `--with-unix-socket-path' option when you run `configure'. See
     *Note configure-options::.

You can test whether the new socket location works by attempting to
connect to the server with this command:

     shell> mysqladmin --socket=/path/to/socket version


File: manual.info,  Node: timezone-problems,  Prev: problems-with-mysql-sock,  Up: administration-issues

B.1.4.8 Time Zone Problems
..........................

If you have a problem with `SELECT NOW()' returning values in UTC and
not your local time, you have to tell the server your current time
zone. The same applies if `UNIX_TIMESTAMP()' returns the wrong value.
This should be done for the environment in which the server runs; for
example, in `mysqld_safe' or `mysql.server'. See *Note
environment-variables::.

You can set the time zone for the server with the
`--timezone=TIMEZONE_NAME' option to `mysqld_safe'. You can also set it
by setting the `TZ' environment variable before you start `mysqld'.

The allowable values for `--timezone' or `TZ' are system-dependent.
Consult your operating system documentation to see what values are
acceptable.


File: manual.info,  Node: query-issues,  Next: optimizer-issues,  Prev: administration-issues,  Up: problems

B.1.5 Query-Related Issues
--------------------------

* Menu:

* case-sensitivity::             Case Sensitivity in String Searches
* using-date::                   Problems Using `DATE' Columns
* problems-with-null::           Problems with `NULL' Values
* problems-with-alias::          Problems with Column Aliases
* non-transactional-tables::     Rollback Failure for Non-Transactional Tables
* deleting-from-related-tables::  Deleting Rows from Related Tables
* no-matching-rows::             Solving Problems with No Matching Rows
* problems-with-float::          Problems with Floating-Point Comparisons


File: manual.info,  Node: case-sensitivity,  Next: using-date,  Prev: query-issues,  Up: query-issues

B.1.5.1 Case Sensitivity in String Searches
...........................................

For non-binary strings (`CHAR', `VARCHAR', `TEXT'), string searches use
the collation of the comparison operands. For binary strings (`BINARY',
`VARBINARY', `BLOB'), comparisons use the numeric values of the bytes
in the operands; this means that for alphabetic characters, comparisons
will be case sensitive.

A comparison between a non-binary string and binary string is treated
as a comparison of binary strings.

Simple comparison operations (`>=, >, =, <, <=', sorting, and grouping)
are based on each character's `sort value.' Characters with the same
sort value are treated as the same character. For example, if ``e'' and
``e''' have the same sort value in a given collation, they compare as
equal.

The default character set and collation are `latin1' and
`latin1_swedish_ci', so non-binary string comparisons are case
insensitive by default. This means that if you search with `COL_NAME
LIKE 'a%'', you get all column values that start with `A' or `a'. To
make this search case sensitive, make sure that one of the operands has
a case sensitive or binary collation. For example, if you are comparing
a column and a string that both have the `latin1' character set, you
can use the `COLLATE' operator to cause either operand to have the
`latin1_general_cs' or `latin1_bin' collation:

     COL_NAME COLLATE latin1_general_cs LIKE 'a%'
     COL_NAME LIKE 'a%' COLLATE latin1_general_cs
     COL_NAME COLLATE latin1_bin LIKE 'a%'
     COL_NAME LIKE 'a%' COLLATE latin1_bin

If you want a column always to be treated in case-sensitive fashion,
declare it with a case sensitive or binary collation.  See *Note
create-table::.

To cause a case-sensitive comparison of non-binary strings to be case
insensitive, use `COLLATE' to name a case-insensitive collation. The
strings in the following example normally are case sensitive, but
`COLLATE' changes the comparison to be case insensitive:

     mysql> SET @s1 = 'MySQL' COLLATE latin1_bin,
         ->     @s2 = 'mysql' COLLATE latin1_bin;
     mysql> SELECT @s1 = @s2;
     +-----------+
     | @s1 = @s2 |
     +-----------+
     |         0 |
     +-----------+
     mysql> SELECT @s1 COLLATE latin1_swedish_ci = @s2;
     +-------------------------------------+
     | @s1 COLLATE latin1_swedish_ci = @s2 |
     +-------------------------------------+
     |                                   1 |
     +-------------------------------------+

A binary string is case sensitive in comparisons. To compare the string
as case insensitive, convert it to a non-binary string and use
`COLLATE' to name a case-insensitive collation:

     mysql> SET @s = BINARY 'MySQL';
     mysql> SELECT @s = 'mysql';
     +--------------+
     | @s = 'mysql' |
     +--------------+
     |            0 |
     +--------------+
     mysql> SELECT CONVERT(@s USING latin1) COLLATE latin1_swedish_ci = 'mysql';
     +--------------------------------------------------------------+
     | CONVERT(@s USING latin1) COLLATE latin1_swedish_ci = 'mysql' |
     +--------------------------------------------------------------+
     |                                                            1 |
     +--------------------------------------------------------------+

To determine whether a value will compare as a non-binary or binary
string, use the `COLLATION()' function. This example shows that
`VERSION()' returns a string that has a case-insensitive collation, so
comparisons are case insensitive:

     mysql> SELECT COLLATION(VERSION());
     +----------------------+
     | COLLATION(VERSION()) |
     +----------------------+
     | utf8_general_ci      |
     +----------------------+

For binary strings, the collation value is `binary', so comparisons
will be case sensitive. One context in which you will see `binary' is
for compression and encryption functions, which return binary strings
as a general rule: string:

     mysql> SELECT COLLATION(ENCRYPT('x')), COLLATION(SHA1('x'));
     +-------------------------+----------------------+
     | COLLATION(ENCRYPT('x')) | COLLATION(SHA1('x')) |
     +-------------------------+----------------------+
     | binary                  | binary               |
     +-------------------------+----------------------+


File: manual.info,  Node: using-date,  Next: problems-with-null,  Prev: case-sensitivity,  Up: query-issues

B.1.5.2 Problems Using `DATE' Columns
.....................................

The format of a `DATE' value is `'YYYY-MM-DD''. According to standard
SQL, no other format is allowed. You should use this format in `UPDATE'
expressions and in the `WHERE' clause of `SELECT' statements. For
example:

     mysql> SELECT * FROM TBL_NAME WHERE date >= '2003-05-05';

As a convenience, MySQL automatically converts a date to a number if
the date is used in a numeric context (and vice versa). It is also
smart enough to allow a `relaxed' string form when updating and in a
`WHERE' clause that compares a date to a `TIMESTAMP', `DATE', or
`DATETIME' column. (`Relaxed form' means that any punctuation character
may be used as the separator between parts. For example, `'2004-08-15''
and `'2004#08#15'' are equivalent.) MySQL can also convert a string
containing no separators (such as `'20040815''), provided it makes
sense as a date.

When you compare a `DATE', `TIME', `DATETIME', or `TIMESTAMP' to a
constant string with the `<', `<=', `=', `>=', `>', or `BETWEEN'
operators, MySQL normally converts the string to an internal long
integer for faster comparison (and also for a bit more `relaxed' string
checking). However, this conversion is subject to the following
exceptions:

   * When you compare two columns

   * When you compare a `DATE', `TIME', `DATETIME', or `TIMESTAMP'
     column to an expression

   * When you use any other comparison method than those just listed,
     such as `IN' or `STRCMP()'.

For these exceptional cases, the comparison is done by converting the
objects to strings and performing a string comparison.

To keep things safe, assume that strings are compared as strings and
use the appropriate string functions if you want to compare a temporal
value to a string.

The special date `'0000-00-00'' can be stored and retrieved as
`'0000-00-00'.' When using a `'0000-00-00'' date through MyODBC, it is
automatically converted to `NULL' in MyODBC 2.50.12 and above, because
ODBC can't handle this kind of date.

Because MySQL performs the conversions described above, the following
statements work:

     mysql> INSERT INTO TBL_NAME (idate) VALUES (19970505);
     mysql> INSERT INTO TBL_NAME (idate) VALUES ('19970505');
     mysql> INSERT INTO TBL_NAME (idate) VALUES ('97-05-05');
     mysql> INSERT INTO TBL_NAME (idate) VALUES ('1997.05.05');
     mysql> INSERT INTO TBL_NAME (idate) VALUES ('1997 05 05');
     mysql> INSERT INTO TBL_NAME (idate) VALUES ('0000-00-00');

     mysql> SELECT idate FROM TBL_NAME WHERE idate >= '1997-05-05';
     mysql> SELECT idate FROM TBL_NAME WHERE idate >= 19970505;
     mysql> SELECT MOD(idate,100) FROM TBL_NAME WHERE idate >= 19970505;
     mysql> SELECT idate FROM TBL_NAME WHERE idate >= '19970505';

However, the following does not work:

     mysql> SELECT idate FROM TBL_NAME WHERE STRCMP(idate,'20030505')=0;

`STRCMP()' is a string function, so it converts `idate' to a string in
`'YYYY-MM-DD'' format and performs a string comparison. It does not
convert `'20030505'' to the date `'2003-05-05'' and perform a date
comparison.

If you are using the `ALLOW_INVALID_DATES' SQL mode, MySQL allows you
to store dates that are given only limited checking: MySQL requires
only that the day is in the range from 1 to 31 and the month is in the
range from 1 to 12.

This makes MySQL very convenient for Web applications where you obtain
year, month, and day in three different fields and you want to store
exactly what the user inserted (without date validation).

If you are not using the `NO_ZERO_IN_DATE' SQL mode, the day or month
part can be zero. This is convenient if you want to store a birthdate
in a `DATE' column and you know only part of the date.

If you are not using the `NO_ZERO_DATE' SQL mode, MySQL also allows you
to store `'0000-00-00'' as a `dummy date.' This is in some cases more
convenient than using `NULL' values.

If the date cannot be converted to any reasonable value, a `0' is
stored in the `DATE' column, which is retrieved as `'0000-00-00''.
This is both a speed and a convenience issue. We believe that the
database server's responsibility is to retrieve the same date you
stored (even if the data was not logically correct in all cases). We
think it is up to the application and not the server to check the dates.

If you want MySQL to check all dates and accept only legal dates
(unless overridden by IGNORE), you should set `sql_mode' to
`"NO_ZERO_IN_DATE,NO_ZERO_DATE"'.


File: manual.info,  Node: problems-with-null,  Next: problems-with-alias,  Prev: using-date,  Up: query-issues

B.1.5.3 Problems with `NULL' Values
...................................

The concept of the `NULL' value is a common source of confusion for
newcomers to SQL, who often think that `NULL' is the same thing as an
empty string `'''. This is not the case. For example, the following
statements are completely different:

     mysql> INSERT INTO my_table (phone) VALUES (NULL);
     mysql> INSERT INTO my_table (phone) VALUES ('');

Both statements insert a value into the `phone' column, but the first
inserts a `NULL' value and the second inserts an empty string. The
meaning of the first can be regarded as `phone number is not known' and
the meaning of the second can be regarded as `the person is known to
have no phone, and thus no phone number.'

To help with `NULL' handling, you can use the `IS NULL' and `IS NOT
NULL' operators and the `IFNULL()' function.

In SQL, the `NULL' value is never true in comparison to any other
value, even `NULL'.  An expression that contains `NULL' always produces
a `NULL' value unless otherwise indicated in the documentation for the
operators and functions involved in the expression. All columns in the
following example return `NULL':

     mysql> SELECT NULL, 1+NULL, CONCAT('Invisible',NULL);

If you want to search for column values that are `NULL', you cannot use
an `expr = NULL' test. The following statement returns no rows, because
`expr = NULL' is never true for any expression:

     mysql> SELECT * FROM my_table WHERE phone = NULL;

To look for `NULL' values, you must use the `IS NULL' test. The
following statements show how to find the `NULL' phone number and the
empty phone number:

     mysql> SELECT * FROM my_table WHERE phone IS NULL;
     mysql> SELECT * FROM my_table WHERE phone = '';

See *Note working-with-null::, for additional information and examples.

You can add an index on a column that can have `NULL' values if you are
using the `MyISAM', `InnoDB', or `MEMORY' storage engine. Otherwise,
you must declare an indexed column `NOT NULL', and you cannot insert
`NULL' into the column.

When reading data with `LOAD DATA INFILE', empty or missing columns are
updated with `'''. If you want a `NULL' value in a column, you should
use `\N' in the data file. The literal word ``NULL'' may also be used
under some circumstances. See *Note load-data::.

When using `DISTINCT', `GROUP BY', or `ORDER BY', all `NULL' values are
regarded as equal.

When using `ORDER BY', `NULL' values are presented first, or last if
you specify `DESC' to sort in descending order.

Aggregate (summary) functions such as `COUNT()', `MIN()', and `SUM()'
ignore `NULL' values. The exception to this is `COUNT(*)', which counts
rows and not individual column values. For example, the following
statement produces two counts. The first is a count of the number of
rows in the table, and the second is a count of the number of
non-`NULL' values in the `age' column:

     mysql> SELECT COUNT(*), COUNT(age) FROM person;

For some data types, MySQL handles `NULL' values specially. If you
insert `NULL' into a `TIMESTAMP' column, the current date and time is
inserted. If you insert `NULL' into an integer or floating-point column
that has the `AUTO_INCREMENT' attribute, the next number in the
sequence is inserted.


File: manual.info,  Node: problems-with-alias,  Next: non-transactional-tables,  Prev: problems-with-null,  Up: query-issues

B.1.5.4 Problems with Column Aliases
....................................

You can use an alias to refer to a column in `GROUP BY', `ORDER BY', or
`HAVING' clauses. Aliases can also be used to give columns better names:

     SELECT SQRT(a*b) AS root FROM TBL_NAME GROUP BY root HAVING root > 0;
     SELECT id, COUNT(*) AS cnt FROM TBL_NAME GROUP BY id HAVING cnt > 0;
     SELECT id AS 'Customer identity' FROM TBL_NAME;

Standard SQL doesn't allow you to refer to a column alias in a `WHERE'
clause. This restriction is imposed because when the `WHERE' code is
executed, the column value may not yet be determined. For example, the
following query is illegal:

     SELECT id, COUNT(*) AS cnt FROM TBL_NAME WHERE cnt > 0 GROUP BY id;

The `WHERE' statement is executed to determine which rows should be
included in the `GROUP BY' part, whereas `HAVING' is used to decide
which rows from the result set should be used.


File: manual.info,  Node: non-transactional-tables,  Next: deleting-from-related-tables,  Prev: problems-with-alias,  Up: query-issues

B.1.5.5 Rollback Failure for Non-Transactional Tables
.....................................................

If you receive the following message when trying to perform a
`ROLLBACK', it means that one or more of the tables you used in the
transaction do not support transactions:

     Warning: Some non-transactional changed tables couldn't be rolled back

These non-transactional tables are not affected by the `ROLLBACK'
statement.

If you were not deliberately mixing transactional and non-transactional
tables within the transaction, the most likely cause for this message
is that a table you thought was transactional actually is not. This can
happen if you try to create a table using a transactional storage
engine that is not supported by your `mysqld' server (or that was
disabled with a startup option). If `mysqld' doesn't support a storage
engine, it instead creates the table as a `MyISAM' table, which is
non-transactional.

You can check the storage engine for a table by using either of these
statements:

     SHOW TABLE STATUS LIKE 'TBL_NAME';
     SHOW CREATE TABLE TBL_NAME;

See *Note show-table-status::, and *Note show-create-table::.

You can check which storage engines your `mysqld' server supports by
using this statement:

     SHOW ENGINES;

You can also use the following statement, and check the value of the
variable that is associated with the storage engine in which you are
interested:

     SHOW VARIABLES LIKE 'have_%';

For example, to determine whether the `InnoDB' storage engine is
available, check the value of the `have_innodb' variable.

See *Note show-engines::, and *Note show-variables::.

MySQL Enterprise

Ensure that your data is adequately protected by subscribing to the
MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: deleting-from-related-tables,  Next: no-matching-rows,  Prev: non-transactional-tables,  Up: query-issues

B.1.5.6 Deleting Rows from Related Tables
.........................................

If the total length of the `DELETE' statement for `related_table' is
more than 1MB (the default value of the `max_allowed_packet' system
variable), you should split it into smaller parts and execute multiple
`DELETE' statements. You probably get the fastest `DELETE' by
specifying only 100 to 1,000 `related_column' values per statement if
the `related_column' is indexed. If the `related_column' isn't indexed,
the speed is independent of the number of arguments in the `IN' clause.


File: manual.info,  Node: no-matching-rows,  Next: problems-with-float,  Prev: deleting-from-related-tables,  Up: query-issues

B.1.5.7 Solving Problems with No Matching Rows
..............................................

If you have a complicated query that uses many tables but that doesn't
return any rows, you should use the following procedure to find out
what is wrong:

  1. Test the query with `EXPLAIN' to check whether you can find
     something that is obviously wrong.  See *Note explain::.

  2. Select only those columns that are used in the `WHERE' clause.

  3. Remove one table at a time from the query until it returns some
     rows. If the tables are large, it's a good idea to use `LIMIT 10'
     with the query.

  4. Issue a `SELECT' for the column that should have matched a row
     against the table that was last removed from the query.

  5. If you are comparing `FLOAT' or `DOUBLE' columns with numbers that
     have decimals, you can't use equality (`=') comparisons. This
     problem is common in most computer languages because not all
     floating-point values can be stored with exact precision. In some
     cases, changing the `FLOAT' to a `DOUBLE' fixes this. See *Note
     problems-with-float::.

  6. If you still can't figure out what's wrong, create a minimal test
     that can be run with `mysql test < query.sql' that shows your
     problems. You can create a test file by dumping the tables with
     `mysqldump --quick db_name TBL_NAME_1 ...  TBL_NAME_N >
     query.sql'. Open the file in an editor, remove some insert lines
     (if there are more than needed to demonstrate the problem), and
     add your `SELECT' statement at the end of the file.

     Verify that the test file demonstrates the problem by executing
     these commands:

          shell> mysqladmin create test2
          shell> mysql test2 < query.sql

     Attach the test file to a bug report, which you can file using the
     instructions in *Note bug-reports::.


File: manual.info,  Node: problems-with-float,  Prev: no-matching-rows,  Up: query-issues

B.1.5.8 Problems with Floating-Point Comparisons
................................................

Floating-point numbers sometimes cause confusion because they are
approximate. That is, they are not stored as exact values inside
computer architecture. What you can see on the screen usually is not
the exact value of the number. The `FLOAT' and `DOUBLE' data types are
such. For `DECIMAL' columns, MySQL performs operations with a precision
of 65 decimal digits, which should solve most common inaccuracy
problems.

The following example demonstrates the problem using `DOUBLE'. It shows
that are calculations that are done using floating-point operations are
subject to floating-point error.

     mysql> CREATE TABLE t1 (i INT, d1 DOUBLE, d2 DOUBLE);
     mysql> INSERT INTO t1 VALUES (1, 101.40, 21.40), (1, -80.00, 0.00),
         -> (2, 0.00, 0.00), (2, -13.20, 0.00), (2, 59.60, 46.40),
         -> (2, 30.40, 30.40), (3, 37.00, 7.40), (3, -29.60, 0.00),
         -> (4, 60.00, 15.40), (4, -10.60, 0.00), (4, -34.00, 0.00),
         -> (5, 33.00, 0.00), (5, -25.80, 0.00), (5, 0.00, 7.20),
         -> (6, 0.00, 0.00), (6, -51.40, 0.00);

     mysql> SELECT i, SUM(d1) AS a, SUM(d2) AS b
         -> FROM t1 GROUP BY i HAVING a <> b;

     +------+-------+------+
     | i    | a     | b    |
     +------+-------+------+
     |    1 |  21.4 | 21.4 |
     |    2 |  76.8 | 76.8 |
     |    3 |   7.4 |  7.4 |
     |    4 |  15.4 | 15.4 |
     |    5 |   7.2 |  7.2 |
     |    6 | -51.4 |    0 |
     +------+-------+------+

The result is correct. Although the first five records look like they
should not satisfy the comparison (the values of `a' and `b' do not
appear to be different), they may do so because the difference between
the numbers shows up around the tenth decimal or so, depending on
factors such as computer architecture or the compiler version or
optimization level. For example, different CPUs may evaluate
floating-point numbers differently.

If columns `d1' and `d2' had been defined as `DECIMAL' rather than
`DOUBLE', the result of the `SELECT' query would have contained only one
row -- the last one shown above.

The correct way to do floating-point number comparison is to first
decide on an acceptable tolerance for differences between the numbers
and then do the comparison against the tolerance value. For example, if
we agree that floating-point numbers should be regarded the same if
they are same within a precision of one in ten thousand (0.0001), the
comparison should be written to find differences larger than the
tolerance value:

     mysql> SELECT i, SUM(d1) AS a, SUM(d2) AS b FROM t1
         -> GROUP BY i HAVING ABS(a - b) > 0.0001;
     +------+-------+------+
     | i    | a     | b    |
     +------+-------+------+
     |    6 | -51.4 |    0 |
     +------+-------+------+
     1 row in set (0.00 sec)

Conversely, to get rows where the numbers are the same, the test should
find differences within the tolerance value:

     mysql> SELECT i, SUM(d1) AS a, SUM(d2) AS b FROM t1
         -> GROUP BY i HAVING ABS(a - b) <= 0.0001;
     +------+------+------+
     | i    | a    | b    |
     +------+------+------+
     |    1 | 21.4 | 21.4 |
     |    2 | 76.8 | 76.8 |
     |    3 |  7.4 |  7.4 |
     |    4 | 15.4 | 15.4 |
     |    5 |  7.2 |  7.2 |
     +------+------+------+
     5 rows in set (0.03 sec)


File: manual.info,  Node: optimizer-issues,  Next: table-definition-issues,  Prev: query-issues,  Up: problems

B.1.6 Optimizer-Related Issues
------------------------------

MySQL uses a cost-based optimizer to determine the best way to resolve
a query. In many cases, MySQL can calculate the best possible query
plan, but sometimes MySQL doesn't have enough information about the
data at hand and has to make `educated' guesses about the data.

For the cases when MySQL does not do the "right" thing, tools that you
have available to help MySQL are:

   * Use the `EXPLAIN' statement to get information about how MySQL
     processes a query. To use it, just add the keyword `EXPLAIN' to
     the front of your `SELECT' statement:

          mysql> EXPLAIN SELECT * FROM t1, t2 WHERE t1.i = t2.i;

     `EXPLAIN' is discussed in more detail in *Note explain::.

   * Use `ANALYZE TABLE TBL_NAME' to update the key distributions for
     the scanned table. See *Note analyze-table::.

   * Use `FORCE INDEX' for the scanned table to tell MySQL that table
     scans are very expensive compared to using the given index:

          SELECT * FROM t1, t2 FORCE INDEX (index_for_column)
          WHERE t1.col_name=t2.col_name;

     `USE INDEX' and `IGNORE INDEX' may also be useful. See *Note
     index-hints::.

   * Global and table-level `STRAIGHT_JOIN'. See *Note select::.

   * You can tune global or thread-specific system variables. For
     example, Start `mysqld' with the `--max-seeks-for-key=1000' option
     or use `SET max_seeks_for_key=1000' to tell the optimizer to
     assume that no key scan causes more than 1,000 key seeks. See
     *Note server-system-variables::.

MySQL Enterprise

For expert advice on configuring MySQL servers for optimal performance,
subscribe to the MySQL Enterprise Monitor. For more information, see
`http://www.mysql.com/products/enterprise/advisors.html'.


File: manual.info,  Node: table-definition-issues,  Next: bugs,  Prev: optimizer-issues,  Up: problems

B.1.7 Table Definition-Related Issues
-------------------------------------

* Menu:

* alter-table-problems::         Problems with `ALTER TABLE'
* change-column-order::          How to Change the Order of Columns in a Table
* temporary-table-problems::     `TEMPORARY TABLE' Problems


File: manual.info,  Node: alter-table-problems,  Next: change-column-order,  Prev: table-definition-issues,  Up: table-definition-issues

B.1.7.1 Problems with `ALTER TABLE'
...................................

`ALTER TABLE' changes a table to the current character set. If you get
a duplicate-key error during `ALTER TABLE', the cause is either that the
new character sets maps two keys to the same value or that the table is
corrupted. In the latter case, you should run `REPAIR TABLE' on the
table.

If `ALTER TABLE' dies with the following error, the problem may be that
MySQL crashed during an earlier `ALTER TABLE' operation and there is an
old table named `A-XXX' or `B-XXX' lying around:

     Error on rename of './database/name.frm'
     to './database/B-XXX.frm' (Errcode: 17)

In this case, go to the MySQL data directory and delete all files that
have names starting with `A-' or `B-'. (You may want to move them
elsewhere instead of deleting them.)

`ALTER TABLE' works in the following way:

   * Create a new table named `A-XXX' with the requested structural
     changes.

   * Copy all rows from the original table to `A-XXX'.

   * Rename the original table to `B-XXX'.

   * Rename `A-XXX' to your original table name.

   * Delete `B-XXX'.

If something goes wrong with the renaming operation, MySQL tries to
undo the changes. If something goes seriously wrong (although this
shouldn't happen), MySQL may leave the old table as `B-XXX'. A simple
rename of the table files at the system level should get your data back.

If you use `ALTER TABLE' on a transactional table or if you are using
Windows or OS/2, `ALTER TABLE' unlocks the table if you had done a
`LOCK TABLE' on it. This is done because `InnoDB' and these operating
systems cannot drop a table that is in use.


File: manual.info,  Node: change-column-order,  Next: temporary-table-problems,  Prev: alter-table-problems,  Up: table-definition-issues

B.1.7.2 How to Change the Order of Columns in a Table
.....................................................

First, consider whether you really need to change the column order in a
table. The whole point of SQL is to abstract the application from the
data storage format. You should always specify the order in which you
wish to retrieve your data. The first of the following statements
returns columns in the order COL_NAME1, COL_NAME2, COL_NAME3, whereas
the second returns them in the order COL_NAME1, COL_NAME3, COL_NAME2:

     mysql> SELECT COL_NAME1, COL_NAME2, COL_NAME3 FROM TBL_NAME;
     mysql> SELECT COL_NAME1, COL_NAME3, COL_NAME2 FROM TBL_NAME;

If you decide to change the order of table columns anyway, you can do
so as follows:

  1. Create a new table with the columns in the new order.

  2. Execute this statement:

          mysql> INSERT INTO new_table
              -> SELECT columns-in-new-order FROM old_table;

  3. Drop or rename `old_table'.

  4. Rename the new table to the original name:

          mysql> ALTER TABLE new_table RENAME old_table;

`SELECT *' is quite suitable for testing queries. However, in an
application, you should _never_ rely on using `SELECT *' and retrieving
the columns based on their position. The order and position in which
columns are returned does not remain the same if you add, move, or
delete columns.  A simple change to your table structure could cause
your application to fail.


File: manual.info,  Node: temporary-table-problems,  Prev: change-column-order,  Up: table-definition-issues

B.1.7.3 `TEMPORARY TABLE' Problems
..................................

The following list indicates limitations on the use of `TEMPORARY'
tables:

   * A `TEMPORARY' table can only be of type `MEMORY', `MyISAM',
     `MERGE', or `InnoDB'.

     Temporary tables are not supported for MySQL Cluster.

   * You cannot refer to a `TEMPORARY' table more than once in the same
     query. For example, the following does not work:

          mysql> SELECT * FROM temp_table, temp_table AS t2;
          ERROR 1137: Can't reopen table: 'temp_table'

     This error also occurs if you refer to a temporary table multiple
     times in a stored function under different aliases, even if the
     references occur in different statements within the function.

   * The `SHOW TABLES' statement does not list `TEMPORARY' tables.

   * You cannot use `RENAME' to rename a `TEMPORARY' table. However,
     you can use `ALTER TABLE' instead:

          mysql> ALTER TABLE orig_name RENAME new_name;

   * There are known issues in using temporary tables with replication.
     See *Note replication-features::, for more information.


File: manual.info,  Node: bugs,  Prev: table-definition-issues,  Up: problems

B.1.8 Known Issues in MySQL
---------------------------

* Menu:

* open-bugs::                    Open Issues in MySQL
* open-bugs-general::            Additional Known Issues

This section is a list of the known issues in recent versions of MySQL.

For information about platform-specific issues, see the installation
and porting instructions in *Note operating-system-specific-notes::, and
MySQL Internals: Porting
(http://forge.mysql.com/wiki/MySQL_Internals_Porting).


File: manual.info,  Node: open-bugs,  Next: open-bugs-general,  Prev: bugs,  Up: bugs

B.1.8.1 Open Issues in MySQL
............................

The following problems are known and fixing them is a high priority:

*Server: Compiling*

   * Bug#32179 (http://bugs.mysql.com/32179): aix52 5.0.50 32-bit
     binary without large file support

*Server: DML*

   * Bug#30776 (http://bugs.mysql.com/30776): `MOD' function produces
     incorrect results with string arguments

*Server: General*

   * Bug#32543 (http://bugs.mysql.com/32543): `ERROR' 2006 (HY000) at
     line 40: MySQL server has gone away

*Server: Installing*

   * Bug#31064 (http://bugs.mysql.com/31064): mysql_upgrade.exe fails

*Server: NDBAPI*

   * Bug#29283 (http://bugs.mysql.com/29283): Ndb_cluster_connection
     seg faults

        * *Target fix*: 5.1+

*Server: Replication*

   * Bug#26980 (http://bugs.mysql.com/26980): binlog_hton->create
     dangling after int binlog_init(void *p)?

        * *Target fix*: 5.1+


File: manual.info,  Node: open-bugs-general,  Prev: open-bugs,  Up: bugs

B.1.8.2 Additional Known Issues
...............................

The following problems are also known and fixing them is also a high
priority:

   * MySQL Cluster fails to recover from an out-of-disk failure when
     using disk data. (Bug#17614 (http://bugs.mysql.com/17614))

   * Subquery optimization for `IN' is not as effective as for `='.

   * Even if you use `lower_case_table_names=2' (which enables MySQL to
     remember the case used for databases and table names), MySQL does
     not remember the case used for database names for the function
     `DATABASE()' or within the various logs (on case-insensitive
     systems).

   * Dropping a `FOREIGN KEY' constraint doesn't work in replication
     because the constraint may have another name on the slave.

   * `REPLACE' (and `LOAD DATA' with the `REPLACE' option) does not
     trigger `ON DELETE CASCADE'.

   * `DISTINCT' with `ORDER BY' doesn't work inside `GROUP_CONCAT()' if
     you don't use all and only those columns that are in the
     `DISTINCT' list.

   * If one user has a long-running transaction and another user drops
     a table that is updated in the transaction, there is small chance
     that the binary log may contain the `DROP TABLE' command before
     the table is used in the transaction itself. We plan to fix this by
     having the `DROP TABLE' command wait until the table is not being
     used in any transaction.

   * When inserting a big integer value (between 2^63 and 2^64-1) into
     a decimal or string column, it is inserted as a negative value
     because the number is evaluated in a signed integer context.

   * `FLUSH TABLES WITH READ LOCK' does not block `COMMIT' if the
     server is running without binary logging, which may cause a
     problem (of consistency between tables) when doing a full backup.

   * `ANALYZE TABLE', `OPTIMIZE TABLE', and `REPAIR TABLE' may cause
     problems on tables for which you are using `INSERT DELAYED'.

   * Performing `LOCK TABLE ...' and `FLUSH TABLES ...' doesn't
     guarantee that there isn't a half-finished transaction in progress
     on the table.

   * Replication uses query-level logging: The master writes the
     executed queries to the binary log. This is a very fast, compact,
     and efficient logging method that works perfectly in most cases.

     It is possible for the data on the master and slave to become
     different if a query is designed in such a way that the data
     modification is non-deterministic (generally not a recommended
     practice, even outside of replication).

     For example:

        * `CREATE ... SELECT' or `INSERT ... SELECT' statements that
          insert zero or `NULL' values into an `AUTO_INCREMENT' column.

        * `DELETE' if you are deleting rows from a table that has
          foreign keys with `ON DELETE CASCADE' properties.

        * `REPLACE ... SELECT', `INSERT IGNORE ... SELECT' if you have
          duplicate key values in the inserted data.

     *If and only if the preceding queries have no `ORDER BY' clause
     guaranteeing a deterministic order*.

     For example, for `INSERT ... SELECT' with no `ORDER BY', the
     `SELECT' may return rows in a different order (which results in a
     row having different ranks, hence getting a different number in the
     `AUTO_INCREMENT' column), depending on the choices made by the
     optimizers on the master and slave.

     A query is optimized differently on the master and slave only if:

        * The table is stored using a different storage engine on the
          master than on the slave. (It is possible to use different
          storage engines on the master and slave.  For example, you
          can use `InnoDB' on the master, but `MyISAM' on the slave if
          the slave has less available disk space.)

        * MySQL buffer sizes (`key_buffer_size', and so on) are
          different on the master and slave.

        * The master and slave run different MySQL versions, and the
          optimizer code differs between these versions.

     This problem may also affect database restoration using
     `mysqlbinlog|mysql'.

     The easiest way to avoid this problem is to add an `ORDER BY'
     clause to the aforementioned non-deterministic queries to ensure
     that the rows are always stored or modified in the same order.

     In future MySQL versions, we will automatically add an `ORDER BY'
     clause when needed.

The following issues are known and will be fixed in due time:

   * Log filenames are based on the server hostname (if you don't
     specify a filename with the startup option). You have to use
     options such as `--log-bin=OLD_HOST_NAME-bin' if you change your
     hostname to something else. Another option is to rename the old
     files to reflect your hostname change (if these are binary logs,
     you need to edit the binary log index file and fix the binlog
     names there as well). See *Note server-options::.

   * `mysqlbinlog' does not delete temporary files left after a `LOAD
     DATA INFILE' command. See *Note mysqlbinlog::.

   * `RENAME' doesn't work with `TEMPORARY' tables or tables used in a
     `MERGE' table.

   * Due to the way table format (`.frm') files are stored, you cannot
     use character 255 (`CHAR(255)') in table names, column names, or
     enumerations. This is scheduled to be fixed in version 5.1 when we
     implement new table definition format files.

   * When using `SET CHARACTER SET', you can't use translated
     characters in database, table, and column names.

   * You can't use ``_'' or ``%'' with `ESCAPE' in `LIKE ...  ESCAPE'.

   * You cannot build the server in another directory when using
     MIT-pthreads. Because this requires changes to MIT-pthreads, we
     are not likely to fix this. See *Note mit-pthreads::.

   * `BLOB' and `TEXT' values can't reliably be used in `GROUP BY',
     `ORDER BY' or `DISTINCT'. Only the first `max_sort_length' bytes
     are used when comparing `BLOB' values in these cases.  The default
     value of `max_sort_length' is 1024 and can be changed at server
     startup time or at runtime.

   * Numeric calculations are done with `BIGINT' or `DOUBLE' (both are
     normally 64 bits long). Which precision you get depends on the
     function. The general rule is that bit functions are performed
     with `BIGINT' precision, `IF' and `ELT()' with `BIGINT' or `DOUBLE'
     precision, and the rest with `DOUBLE' precision. You should try to
     avoid using unsigned long long values if they resolve to be larger
     than 63 bits (9223372036854775807) for anything other than bit
     fields.

   * You can have up to 255 `ENUM' and `SET' columns in one table.

   * In `MIN()', `MAX()', and other aggregate functions, MySQL
     currently compares `ENUM' and `SET' columns by their string value
     rather than by the string's relative position in the set.

   * `mysqld_safe' redirects all messages from `mysqld' to the `mysqld'
     log. One problem with this is that if you execute `mysqladmin
     refresh' to close and reopen the log, `stdout' and `stderr' are
     still redirected to the old log. If you use `--log' extensively,
     you should edit `mysqld_safe' to log to `HOST_NAME.err' instead of
     `HOST_NAME.log' so that you can easily reclaim the space for the
     old log by deleting it and executing `mysqladmin refresh'.

   * In an `UPDATE' statement, columns are updated from left to right.
     If you refer to an updated column, you get the updated value
     instead of the original value. For example, the following
     statement increments `KEY' by `2', *not* `1':

          mysql> UPDATE TBL_NAME SET KEY=KEY+1,KEY=KEY+1;

   * You can refer to multiple temporary tables in the same query, but
     you cannot refer to any given temporary table more than once. For
     example, the following doesn't work:

          mysql> SELECT * FROM temp_table, temp_table AS t2;
          ERROR 1137: Can't reopen table: 'temp_table'

   * The optimizer may handle `DISTINCT' differently when you are using
     `hidden' columns in a join than when you are not. In a join, hidden
     columns are counted as part of the result (even if they are not
     shown), whereas in normal queries, hidden columns don't
     participate in the `DISTINCT' comparison. We will probably change
     this in the future to never compare the hidden columns when
     executing `DISTINCT'.

     An example of this is:

          SELECT DISTINCT mp3id FROM band_downloads
                 WHERE userid = 9 ORDER BY id DESC;

     and

          SELECT DISTINCT band_downloads.mp3id
                 FROM band_downloads,band_mp3
                 WHERE band_downloads.userid = 9
                 AND band_mp3.id = band_downloads.mp3id
                 ORDER BY band_downloads.id DESC;

     In the second case, using MySQL Server 3.23.x, you may get two
     identical rows in the result set (because the values in the hidden
     `id' column may differ).

     Note that this happens only for queries where that do not have the
     `ORDER BY' columns in the result.

   * If you execute a `PROCEDURE' on a query that returns an empty set,
     in some cases the `PROCEDURE' does not transform the columns.

   * Creation of a table of type `MERGE' doesn't check whether the
     underlying tables are compatible types.

   * If you use `ALTER TABLE' to add a `UNIQUE' index to a table used
     in a `MERGE' table and then add a normal index on the `MERGE'
     table, the key order is different for the tables if there was an
     old, non-`UNIQUE' key in the table. This is because `ALTER TABLE'
     puts `UNIQUE' indexes before normal indexes to be able to detect
     duplicate keys as early as possible.


File: manual.info,  Node: error-messages-server,  Next: error-messages-client,  Prev: problems,  Up: error-handling

B.2 Server Error Codes and Messages
===================================

MySQL programs have access to several types of error information when
the server returns an error. For example, the `mysql' client program
displays errors using the following format:

     shell> SELECT * FROM no_such_table;
     ERROR 1146 (42S02): Table 'test.no_such_table' doesn't exist

The message displayed contains three types of information:

   * A numeric error value (`1146'). This number is MySQL-specific and
     is not portable to other database systems.

   * A five-character SQLSTATE value (`'42S02'').  The values are
     specified by ANSI SQL and ODBC and are more standardized. Not all
     MySQL error numbers are mapped to SQLSTATE error codes. The value
     `'HY000'' (general error) is used for unmapped errors.

   * A string that provides a textual description of the error.

Server error information comes from the following source files.  For
details about the way that error information is defined, see the MySQL
Internals manual, available at `http://dev.mysql.com/doc/'.

   * Error message information is listed in the `share/errmsg.txt' file.
     `%d' and `%s' represent numbers and strings, respectively, that
     are substituted into the Message values when they are displayed.

   * The Error values listed in `share/errmsg.txt' are used to generate
     the definitions in the `include/mysqld_error.h' and
     `include/mysqld_ername.h' MySQL source files.

   * The SQLSTATE values listed in `share/errmsg.txt' are used to
     generate the definitions in the `include/sql_state.h' MySQL source
     file.

Because updates are frequent, it is possible that those files will
contain additional error information not listed here.

   * Error: `1000' SQLSTATE: `HY000' (`ER_HASHCHK')

     Message: hashchk

   * Error: `1001' SQLSTATE: `HY000' (`ER_NISAMCHK')

     Message: isamchk

   * Error: `1002' SQLSTATE: `HY000' (`ER_NO')

     Message: NO

   * Error: `1003' SQLSTATE: `HY000' (`ER_YES')

     Message: YES

   * Error: `1004' SQLSTATE: `HY000' (`ER_CANT_CREATE_FILE')

     Message: Can't create file '%s' (errno: %d)

   * Error: `1005' SQLSTATE: `HY000' (`ER_CANT_CREATE_TABLE')

     Message: Can't create table '%s' (errno: %d)

   * Error: `1006' SQLSTATE: `HY000' (`ER_CANT_CREATE_DB')

     Message: Can't create database '%s' (errno: %d)

   * Error: `1007' SQLSTATE: `HY000' (`ER_DB_CREATE_EXISTS')

     Message: Can't create database '%s'; database exists

   * Error: `1008' SQLSTATE: `HY000' (`ER_DB_DROP_EXISTS')

     Message: Can't drop database '%s'; database doesn't exist

   * Error: `1009' SQLSTATE: `HY000' (`ER_DB_DROP_DELETE')

     Message: Error dropping database (can't delete '%s', errno: %d)

   * Error: `1010' SQLSTATE: `HY000' (`ER_DB_DROP_RMDIR')

     Message: Error dropping database (can't rmdir '%s', errno: %d)

   * Error: `1011' SQLSTATE: `HY000' (`ER_CANT_DELETE_FILE')

     Message: Error on delete of '%s' (errno: %d)

   * Error: `1012' SQLSTATE: `HY000' (`ER_CANT_FIND_SYSTEM_REC')

     Message: Can't read record in system table

   * Error: `1013' SQLSTATE: `HY000' (`ER_CANT_GET_STAT')

     Message: Can't get status of '%s' (errno: %d)

   * Error: `1014' SQLSTATE: `HY000' (`ER_CANT_GET_WD')

     Message: Can't get working directory (errno: %d)

   * Error: `1015' SQLSTATE: `HY000' (`ER_CANT_LOCK')

     Message: Can't lock file (errno: %d)

   * Error: `1016' SQLSTATE: `HY000' (`ER_CANT_OPEN_FILE')

     Message: Can't open file: '%s' (errno: %d)

   * Error: `1017' SQLSTATE: `HY000' (`ER_FILE_NOT_FOUND')

     Message: Can't find file: '%s' (errno: %d)

   * Error: `1018' SQLSTATE: `HY000' (`ER_CANT_READ_DIR')

     Message: Can't read dir of '%s' (errno: %d)

   * Error: `1019' SQLSTATE: `HY000' (`ER_CANT_SET_WD')

     Message: Can't change dir to '%s' (errno: %d)

   * Error: `1020' SQLSTATE: `HY000' (`ER_CHECKREAD')

     Message: Record has changed since last read in table '%s'

   * Error: `1021' SQLSTATE: `HY000' (`ER_DISK_FULL')

     Message: Disk full (%s); waiting for someone to free some space...

   * Error: `1022' SQLSTATE: `23000' (`ER_DUP_KEY')

     Message: Can't write; duplicate key in table '%s'

   * Error: `1023' SQLSTATE: `HY000' (`ER_ERROR_ON_CLOSE')

     Message: Error on close of '%s' (errno: %d)

   * Error: `1024' SQLSTATE: `HY000' (`ER_ERROR_ON_READ')

     Message: Error reading file '%s' (errno: %d)

   * Error: `1025' SQLSTATE: `HY000' (`ER_ERROR_ON_RENAME')

     Message: Error on rename of '%s' to '%s' (errno: %d)

   * Error: `1026' SQLSTATE: `HY000' (`ER_ERROR_ON_WRITE')

     Message: Error writing file '%s' (errno: %d)

   * Error: `1027' SQLSTATE: `HY000' (`ER_FILE_USED')

     Message: '%s' is locked against change

   * Error: `1028' SQLSTATE: `HY000' (`ER_FILSORT_ABORT')

     Message: Sort aborted

   * Error: `1029' SQLSTATE: `HY000' (`ER_FORM_NOT_FOUND')

     Message: View '%s' doesn't exist for '%s'

   * Error: `1030' SQLSTATE: `HY000' (`ER_GET_ERRNO')

     Message: Got error %d from storage engine

   * Error: `1031' SQLSTATE: `HY000' (`ER_ILLEGAL_HA')

     Message: Table storage engine for '%s' doesn't have this option

   * Error: `1032' SQLSTATE: `HY000' (`ER_KEY_NOT_FOUND')

     Message: Can't find record in '%s'

   * Error: `1033' SQLSTATE: `HY000' (`ER_NOT_FORM_FILE')

     Message: Incorrect information in file: '%s'

   * Error: `1034' SQLSTATE: `HY000' (`ER_NOT_KEYFILE')

     Message: Incorrect key file for table '%s'; try to repair it

   * Error: `1035' SQLSTATE: `HY000' (`ER_OLD_KEYFILE')

     Message: Old key file for table '%s'; repair it!

   * Error: `1036' SQLSTATE: `HY000' (`ER_OPEN_AS_READONLY')

     Message: Table '%s' is read only

   * Error: `1037' SQLSTATE: `HY001' (`ER_OUTOFMEMORY')

     Message: Out of memory; restart server and try again (needed %d
     bytes)

   * Error: `1038' SQLSTATE: `HY001' (`ER_OUT_OF_SORTMEMORY')

     Message: Out of sort memory; increase server sort buffer size

   * Error: `1039' SQLSTATE: `HY000' (`ER_UNEXPECTED_EOF')

     Message: Unexpected EOF found when reading file '%s' (errno: %d)

   * Error: `1040' SQLSTATE: `08004' (`ER_CON_COUNT_ERROR')

     Message: Too many connections

   * Error: `1041' SQLSTATE: `HY000' (`ER_OUT_OF_RESOURCES')

     Message: Out of memory; check if mysqld or some other process uses
     all available memory; if not, you may have to use 'ulimit' to
     allow mysqld to use more memory or you can add more swap space

   * Error: `1042' SQLSTATE: `08S01' (`ER_BAD_HOST_ERROR')

     Message: Can't get hostname for your address

   * Error: `1043' SQLSTATE: `08S01' (`ER_HANDSHAKE_ERROR')

     Message: Bad handshake

   * Error: `1044' SQLSTATE: `42000' (`ER_DBACCESS_DENIED_ERROR')

     Message: Access denied for user '%s'@'%s' to database '%s'

   * Error: `1045' SQLSTATE: `28000' (`ER_ACCESS_DENIED_ERROR')

     Message: Access denied for user '%s'@'%s' (using password: %s)

   * Error: `1046' SQLSTATE: `3D000' (`ER_NO_DB_ERROR')

     Message: No database selected

   * Error: `1047' SQLSTATE: `08S01' (`ER_UNKNOWN_COM_ERROR')

     Message: Unknown command

   * Error: `1048' SQLSTATE: `23000' (`ER_BAD_NULL_ERROR')

     Message: Column '%s' cannot be null

   * Error: `1049' SQLSTATE: `42000' (`ER_BAD_DB_ERROR')

     Message: Unknown database '%s'

   * Error: `1050' SQLSTATE: `42S01' (`ER_TABLE_EXISTS_ERROR')

     Message: Table '%s' already exists

   * Error: `1051' SQLSTATE: `42S02' (`ER_BAD_TABLE_ERROR')

     Message: Unknown table '%s'

   * Error: `1052' SQLSTATE: `23000' (`ER_NON_UNIQ_ERROR')

     Message: Column '%s' in %s is ambiguous

   * Error: `1053' SQLSTATE: `08S01' (`ER_SERVER_SHUTDOWN')

     Message: Server shutdown in progress

   * Error: `1054' SQLSTATE: `42S22' (`ER_BAD_FIELD_ERROR')

     Message: Unknown column '%s' in '%s'

   * Error: `1055' SQLSTATE: `42000' (`ER_WRONG_FIELD_WITH_GROUP')

     Message: '%s' isn't in GROUP BY

   * Error: `1056' SQLSTATE: `42000' (`ER_WRONG_GROUP_FIELD')

     Message: Can't group on '%s'

   * Error: `1057' SQLSTATE: `42000' (`ER_WRONG_SUM_SELECT')

     Message: Statement has sum functions and columns in same statement

   * Error: `1058' SQLSTATE: `21S01' (`ER_WRONG_VALUE_COUNT')

     Message: Column count doesn't match value count

   * Error: `1059' SQLSTATE: `42000' (`ER_TOO_LONG_IDENT')

     Message: Identifier name '%s' is too long

   * Error: `1060' SQLSTATE: `42S21' (`ER_DUP_FIELDNAME')

     Message: Duplicate column name '%s'

   * Error: `1061' SQLSTATE: `42000' (`ER_DUP_KEYNAME')

     Message: Duplicate key name '%s'

   * Error: `1062' SQLSTATE: `23000' (`ER_DUP_ENTRY')

     Message: Duplicate entry '%s' for key %d

   * Error: `1063' SQLSTATE: `42000' (`ER_WRONG_FIELD_SPEC')

     Message: Incorrect column specifier for column '%s'

   * Error: `1064' SQLSTATE: `42000' (`ER_PARSE_ERROR')

     Message: %s near '%s' at line %d

   * Error: `1065' SQLSTATE: `42000' (`ER_EMPTY_QUERY')

     Message: Query was empty

   * Error: `1066' SQLSTATE: `42000' (`ER_NONUNIQ_TABLE')

     Message: Not unique table/alias: '%s'

   * Error: `1067' SQLSTATE: `42000' (`ER_INVALID_DEFAULT')

     Message: Invalid default value for '%s'

   * Error: `1068' SQLSTATE: `42000' (`ER_MULTIPLE_PRI_KEY')

     Message: Multiple primary key defined

   * Error: `1069' SQLSTATE: `42000' (`ER_TOO_MANY_KEYS')

     Message: Too many keys specified; max %d keys allowed

   * Error: `1070' SQLSTATE: `42000' (`ER_TOO_MANY_KEY_PARTS')

     Message: Too many key parts specified; max %d parts allowed

   * Error: `1071' SQLSTATE: `42000' (`ER_TOO_LONG_KEY')

     Message: Specified key was too long; max key length is %d bytes

   * Error: `1072' SQLSTATE: `42000' (`ER_KEY_COLUMN_DOES_NOT_EXITS')

     Message: Key column '%s' doesn't exist in table

   * Error: `1073' SQLSTATE: `42000' (`ER_BLOB_USED_AS_KEY')

     Message: BLOB column '%s' can't be used in key specification with
     the used table type

   * Error: `1074' SQLSTATE: `42000' (`ER_TOO_BIG_FIELDLENGTH')

     Message: Column length too big for column '%s' (max = %lu); use
     BLOB or TEXT instead

   * Error: `1075' SQLSTATE: `42000' (`ER_WRONG_AUTO_KEY')

     Message: Incorrect table definition; there can be only one auto
     column and it must be defined as a key

   * Error: `1076' SQLSTATE: `HY000' (`ER_READY')

     Message: %s: ready for connections. Version: '%s' socket: '%s'
     port: %d

   * Error: `1077' SQLSTATE: `HY000' (`ER_NORMAL_SHUTDOWN')

     Message: %s: Normal shutdown

   * Error: `1078' SQLSTATE: `HY000' (`ER_GOT_SIGNAL')

     Message: %s: Got signal %d. Aborting!

   * Error: `1079' SQLSTATE: `HY000' (`ER_SHUTDOWN_COMPLETE')

     Message: %s: Shutdown complete

   * Error: `1080' SQLSTATE: `08S01' (`ER_FORCING_CLOSE')

     Message: %s: Forcing close of thread %ld user: '%s'

   * Error: `1081' SQLSTATE: `08S01' (`ER_IPSOCK_ERROR')

     Message: Can't create IP socket

   * Error: `1082' SQLSTATE: `42S12' (`ER_NO_SUCH_INDEX')

     Message: Table '%s' has no index like the one used in CREATE
     INDEX; recreate the table

   * Error: `1083' SQLSTATE: `42000' (`ER_WRONG_FIELD_TERMINATORS')

     Message: Field separator argument is not what is expected; check
     the manual

   * Error: `1084' SQLSTATE: `42000' (`ER_BLOBS_AND_NO_TERMINATED')

     Message: You can't use fixed rowlength with BLOBs; please use
     'fields terminated by'

   * Error: `1085' SQLSTATE: `HY000' (`ER_TEXTFILE_NOT_READABLE')

     Message: The file '%s' must be in the database directory or be
     readable by all

   * Error: `1086' SQLSTATE: `HY000' (`ER_FILE_EXISTS_ERROR')

     Message: File '%s' already exists

   * Error: `1087' SQLSTATE: `HY000' (`ER_LOAD_INFO')

     Message: Records: %ld Deleted: %ld Skipped: %ld Warnings: %ld

   * Error: `1088' SQLSTATE: `HY000' (`ER_ALTER_INFO')

     Message: Records: %ld Duplicates: %ld

   * Error: `1089' SQLSTATE: `HY000' (`ER_WRONG_SUB_KEY')

     Message: Incorrect prefix key; the used key part isn't a string,
     the used length is longer than the key part, or the storage engine
     doesn't support unique prefix keys

   * Error: `1090' SQLSTATE: `42000' (`ER_CANT_REMOVE_ALL_FIELDS')

     Message: You can't delete all columns with ALTER TABLE; use DROP
     TABLE instead

   * Error: `1091' SQLSTATE: `42000' (`ER_CANT_DROP_FIELD_OR_KEY')

     Message: Can't DROP '%s'; check that column/key exists

   * Error: `1092' SQLSTATE: `HY000' (`ER_INSERT_INFO')

     Message: Records: %ld Duplicates: %ld Warnings: %ld

   * Error: `1093' SQLSTATE: `HY000' (`ER_UPDATE_TABLE_USED')

     Message: You can't specify target table '%s' for update in FROM
     clause

   * Error: `1094' SQLSTATE: `HY000' (`ER_NO_SUCH_THREAD')

     Message: Unknown thread id: %lu

   * Error: `1095' SQLSTATE: `HY000' (`ER_KILL_DENIED_ERROR')

     Message: You are not owner of thread %lu

   * Error: `1096' SQLSTATE: `HY000' (`ER_NO_TABLES_USED')

     Message: No tables used

   * Error: `1097' SQLSTATE: `HY000' (`ER_TOO_BIG_SET')

     Message: Too many strings for column %s and SET

   * Error: `1098' SQLSTATE: `HY000' (`ER_NO_UNIQUE_LOGFILE')

     Message: Can't generate a unique log-filename %s.(1-999)

   * Error: `1099' SQLSTATE: `HY000' (`ER_TABLE_NOT_LOCKED_FOR_WRITE')

     Message: Table '%s' was locked with a READ lock and can't be
     updated

   * Error: `1100' SQLSTATE: `HY000' (`ER_TABLE_NOT_LOCKED')

     Message: Table '%s' was not locked with LOCK TABLES

   * Error: `1101' SQLSTATE: `42000' (`ER_BLOB_CANT_HAVE_DEFAULT')

     Message: BLOB/TEXT column '%s' can't have a default value

   * Error: `1102' SQLSTATE: `42000' (`ER_WRONG_DB_NAME')

     Message: Incorrect database name '%s'

   * Error: `1103' SQLSTATE: `42000' (`ER_WRONG_TABLE_NAME')

     Message: Incorrect table name '%s'

   * Error: `1104' SQLSTATE: `42000' (`ER_TOO_BIG_SELECT')

     Message: The SELECT would examine more than MAX_JOIN_SIZE rows;
     check your WHERE and use SET SQL_BIG_SELECTS=1 or SET
     SQL_MAX_JOIN_SIZE=# if the SELECT is okay

   * Error: `1105' SQLSTATE: `HY000' (`ER_UNKNOWN_ERROR')

     Message: Unknown error

   * Error: `1106' SQLSTATE: `42000' (`ER_UNKNOWN_PROCEDURE')

     Message: Unknown procedure '%s'

   * Error: `1107' SQLSTATE: `42000'
     (`ER_WRONG_PARAMCOUNT_TO_PROCEDURE')

     Message: Incorrect parameter count to procedure '%s'

   * Error: `1108' SQLSTATE: `HY000'
     (`ER_WRONG_PARAMETERS_TO_PROCEDURE')

     Message: Incorrect parameters to procedure '%s'

   * Error: `1109' SQLSTATE: `42S02' (`ER_UNKNOWN_TABLE')

     Message: Unknown table '%s' in %s

   * Error: `1110' SQLSTATE: `42000' (`ER_FIELD_SPECIFIED_TWICE')

     Message: Column '%s' specified twice

   * Error: `1111' SQLSTATE: `HY000' (`ER_INVALID_GROUP_FUNC_USE')

     Message: Invalid use of group function

   * Error: `1112' SQLSTATE: `42000' (`ER_UNSUPPORTED_EXTENSION')

     Message: Table '%s' uses an extension that doesn't exist in this
     MySQL version

   * Error: `1113' SQLSTATE: `42000' (`ER_TABLE_MUST_HAVE_COLUMNS')

     Message: A table must have at least 1 column

   * Error: `1114' SQLSTATE: `HY000' (`ER_RECORD_FILE_FULL')

     Message: The table '%s' is full

   * Error: `1115' SQLSTATE: `42000' (`ER_UNKNOWN_CHARACTER_SET')

     Message: Unknown character set: '%s'

   * Error: `1116' SQLSTATE: `HY000' (`ER_TOO_MANY_TABLES')

     Message: Too many tables; MySQL can only use %d tables in a join

   * Error: `1117' SQLSTATE: `HY000' (`ER_TOO_MANY_FIELDS')

     Message: Too many columns

   * Error: `1118' SQLSTATE: `42000' (`ER_TOO_BIG_ROWSIZE')

     Message: Row size too large. The maximum row size for the used
     table type, not counting BLOBs, is %ld. You have to change some
     columns to TEXT or BLOBs

   * Error: `1119' SQLSTATE: `HY000' (`ER_STACK_OVERRUN')

     Message: Thread stack overrun: Used: %ld of a %ld stack. Use
     'mysqld -O thread_stack=#' to specify a bigger stack if needed

   * Error: `1120' SQLSTATE: `42000' (`ER_WRONG_OUTER_JOIN')

     Message: Cross dependency found in OUTER JOIN; examine your ON
     conditions

   * Error: `1121' SQLSTATE: `42000' (`ER_NULL_COLUMN_IN_INDEX')

     Message: Table handler doesn't support NULL in given index. Please
     change column '%s' to be NOT NULL or use another handler

   * Error: `1122' SQLSTATE: `HY000' (`ER_CANT_FIND_UDF')

     Message: Can't load function '%s'

   * Error: `1123' SQLSTATE: `HY000' (`ER_CANT_INITIALIZE_UDF')

     Message: Can't initialize function '%s'; %s

   * Error: `1124' SQLSTATE: `HY000' (`ER_UDF_NO_PATHS')

     Message: No paths allowed for shared library

   * Error: `1125' SQLSTATE: `HY000' (`ER_UDF_EXISTS')

     Message: Function '%s' already exists

   * Error: `1126' SQLSTATE: `HY000' (`ER_CANT_OPEN_LIBRARY')

     Message: Can't open shared library '%s' (errno: %d %s)

   * Error: `1127' SQLSTATE: `HY000' (`ER_CANT_FIND_DL_ENTRY')

     Message: Can't find symbol '%s' in library

   * Error: `1128' SQLSTATE: `HY000' (`ER_FUNCTION_NOT_DEFINED')

     Message: Function '%s' is not defined

   * Error: `1129' SQLSTATE: `HY000' (`ER_HOST_IS_BLOCKED')

     Message: Host '%s' is blocked because of many connection errors;
     unblock with 'mysqladmin flush-hosts'

   * Error: `1130' SQLSTATE: `HY000' (`ER_HOST_NOT_PRIVILEGED')

     Message: Host '%s' is not allowed to connect to this MySQL server

   * Error: `1131' SQLSTATE: `42000' (`ER_PASSWORD_ANONYMOUS_USER')

     Message: You are using MySQL as an anonymous user and anonymous
     users are not allowed to change passwords

   * Error: `1132' SQLSTATE: `42000' (`ER_PASSWORD_NOT_ALLOWED')

     Message: You must have privileges to update tables in the mysql
     database to be able to change passwords for others

   * Error: `1133' SQLSTATE: `42000' (`ER_PASSWORD_NO_MATCH')

     Message: Can't find any matching row in the user table

   * Error: `1134' SQLSTATE: `HY000' (`ER_UPDATE_INFO')

     Message: Rows matched: %ld Changed: %ld Warnings: %ld

   * Error: `1135' SQLSTATE: `HY000' (`ER_CANT_CREATE_THREAD')

     Message: Can't create a new thread (errno %d); if you are not out
     of available memory, you can consult the manual for a possible
     OS-dependent bug

   * Error: `1136' SQLSTATE: `21S01' (`ER_WRONG_VALUE_COUNT_ON_ROW')

     Message: Column count doesn't match value count at row %ld

   * Error: `1137' SQLSTATE: `HY000' (`ER_CANT_REOPEN_TABLE')

     Message: Can't reopen table: '%s'

   * Error: `1138' SQLSTATE: `22004' (`ER_INVALID_USE_OF_NULL')

     Message: Invalid use of NULL value

   * Error: `1139' SQLSTATE: `42000' (`ER_REGEXP_ERROR')

     Message: Got error '%s' from regexp

   * Error: `1140' SQLSTATE: `42000' (`ER_MIX_OF_GROUP_FUNC_AND_FIELDS')

     Message: Mixing of GROUP columns (MIN(),MAX(),COUNT(),...) with no
     GROUP columns is illegal if there is no GROUP BY clause

   * Error: `1141' SQLSTATE: `42000' (`ER_NONEXISTING_GRANT')

     Message: There is no such grant defined for user '%s' on host '%s'

   * Error: `1142' SQLSTATE: `42000' (`ER_TABLEACCESS_DENIED_ERROR')

     Message: %s command denied to user '%s'@'%s' for table '%s'

   * Error: `1143' SQLSTATE: `42000' (`ER_COLUMNACCESS_DENIED_ERROR')

     Message: %s command denied to user '%s'@'%s' for column '%s' in
     table '%s'

   * Error: `1144' SQLSTATE: `42000' (`ER_ILLEGAL_GRANT_FOR_TABLE')

     Message: Illegal GRANT/REVOKE command; please consult the manual
     to see which privileges can be used

   * Error: `1145' SQLSTATE: `42000' (`ER_GRANT_WRONG_HOST_OR_USER')

     Message: The host or user argument to GRANT is too long

   * Error: `1146' SQLSTATE: `42S02' (`ER_NO_SUCH_TABLE')

     Message: Table '%s.%s' doesn't exist

   * Error: `1147' SQLSTATE: `42000' (`ER_NONEXISTING_TABLE_GRANT')

     Message: There is no such grant defined for user '%s' on host '%s'
     on table '%s'

   * Error: `1148' SQLSTATE: `42000' (`ER_NOT_ALLOWED_COMMAND')

     Message: The used command is not allowed with this MySQL version

   * Error: `1149' SQLSTATE: `42000' (`ER_SYNTAX_ERROR')

     Message: You have an error in your SQL syntax; check the manual
     that corresponds to your MySQL server version for the right syntax
     to use

   * Error: `1150' SQLSTATE: `HY000' (`ER_DELAYED_CANT_CHANGE_LOCK')

     Message: Delayed insert thread couldn't get requested lock for
     table %s

   * Error: `1151' SQLSTATE: `HY000' (`ER_TOO_MANY_DELAYED_THREADS')

     Message: Too many delayed threads in use

   * Error: `1152' SQLSTATE: `08S01' (`ER_ABORTING_CONNECTION')

     Message: Aborted connection %ld to db: '%s' user: '%s' (%s)

   * Error: `1153' SQLSTATE: `08S01' (`ER_NET_PACKET_TOO_LARGE')

     Message: Got a packet bigger than 'max_allowed_packet' bytes

   * Error: `1154' SQLSTATE: `08S01' (`ER_NET_READ_ERROR_FROM_PIPE')

     Message: Got a read error from the connection pipe

   * Error: `1155' SQLSTATE: `08S01' (`ER_NET_FCNTL_ERROR')

     Message: Got an error from fcntl()

   * Error: `1156' SQLSTATE: `08S01' (`ER_NET_PACKETS_OUT_OF_ORDER')

     Message: Got packets out of order

   * Error: `1157' SQLSTATE: `08S01' (`ER_NET_UNCOMPRESS_ERROR')

     Message: Couldn't uncompress communication packet

   * Error: `1158' SQLSTATE: `08S01' (`ER_NET_READ_ERROR')

     Message: Got an error reading communication packets

   * Error: `1159' SQLSTATE: `08S01' (`ER_NET_READ_INTERRUPTED')

     Message: Got timeout reading communication packets

   * Error: `1160' SQLSTATE: `08S01' (`ER_NET_ERROR_ON_WRITE')

     Message: Got an error writing communication packets

   * Error: `1161' SQLSTATE: `08S01' (`ER_NET_WRITE_INTERRUPTED')

     Message: Got timeout writing communication packets

   * Error: `1162' SQLSTATE: `42000' (`ER_TOO_LONG_STRING')

     Message: Result string is longer than 'max_allowed_packet' bytes

   * Error: `1163' SQLSTATE: `42000' (`ER_TABLE_CANT_HANDLE_BLOB')

     Message: The used table type doesn't support BLOB/TEXT columns

   * Error: `1164' SQLSTATE: `42000'
     (`ER_TABLE_CANT_HANDLE_AUTO_INCREMENT')

     Message: The used table type doesn't support AUTO_INCREMENT columns

   * Error: `1165' SQLSTATE: `HY000' (`ER_DELAYED_INSERT_TABLE_LOCKED')

     Message: INSERT DELAYED can't be used with table '%s' because it
     is locked with LOCK TABLES

   * Error: `1166' SQLSTATE: `42000' (`ER_WRONG_COLUMN_NAME')

     Message: Incorrect column name '%s'

   * Error: `1167' SQLSTATE: `42000' (`ER_WRONG_KEY_COLUMN')

     Message: The used storage engine can't index column '%s'

   * Error: `1168' SQLSTATE: `HY000' (`ER_WRONG_MRG_TABLE')

     Message: Unable to open underlying table which is differently
     defined or of non-MyISAM type or doesn't exist

   * Error: `1169' SQLSTATE: `23000' (`ER_DUP_UNIQUE')

     Message: Can't write, because of unique constraint, to table '%s'

   * Error: `1170' SQLSTATE: `42000' (`ER_BLOB_KEY_WITHOUT_LENGTH')

     Message: BLOB/TEXT column '%s' used in key specification without a
     key length

   * Error: `1171' SQLSTATE: `42000' (`ER_PRIMARY_CANT_HAVE_NULL')

     Message: All parts of a PRIMARY KEY must be NOT NULL; if you need
     NULL in a key, use UNIQUE instead

   * Error: `1172' SQLSTATE: `42000' (`ER_TOO_MANY_ROWS')

     Message: Result consisted of more than one row

   * Error: `1173' SQLSTATE: `42000' (`ER_REQUIRES_PRIMARY_KEY')

     Message: This table type requires a primary key

   * Error: `1174' SQLSTATE: `HY000' (`ER_NO_RAID_COMPILED')

     Message: This version of MySQL is not compiled with RAID support

   * Error: `1175' SQLSTATE: `HY000'
     (`ER_UPDATE_WITHOUT_KEY_IN_SAFE_MODE')

     Message: You are using safe update mode and you tried to update a
     table without a WHERE that uses a KEY column

   * Error: `1176' SQLSTATE: `42000' (`ER_KEY_DOES_NOT_EXITS')

     Message: Key '%s' doesn't exist in table '%s'

   * Error: `1177' SQLSTATE: `42000' (`ER_CHECK_NO_SUCH_TABLE')

     Message: Can't open table

   * Error: `1178' SQLSTATE: `42000' (`ER_CHECK_NOT_IMPLEMENTED')

     Message: The storage engine for the table doesn't support %s

   * Error: `1179' SQLSTATE: `25000'
     (`ER_CANT_DO_THIS_DURING_AN_TRANSACTION')

     Message: You are not allowed to execute this command in a
     transaction

   * Error: `1180' SQLSTATE: `HY000' (`ER_ERROR_DURING_COMMIT')

     Message: Got error %d during COMMIT

   * Error: `1181' SQLSTATE: `HY000' (`ER_ERROR_DURING_ROLLBACK')

     Message: Got error %d during ROLLBACK

   * Error: `1182' SQLSTATE: `HY000' (`ER_ERROR_DURING_FLUSH_LOGS')

     Message: Got error %d during FLUSH_LOGS

   * Error: `1183' SQLSTATE: `HY000' (`ER_ERROR_DURING_CHECKPOINT')

     Message: Got error %d during CHECKPOINT

   * Error: `1184' SQLSTATE: `08S01' (`ER_NEW_ABORTING_CONNECTION')

     Message: Aborted connection %ld to db: '%s' user: '%s' host: '%s'
     (%s)

   * Error: `1185' SQLSTATE: `HY000' (`ER_DUMP_NOT_IMPLEMENTED')

     Message: The storage engine for the table does not support binary
     table dump

   * Error: `1186' SQLSTATE: `HY000' (`ER_FLUSH_MASTER_BINLOG_CLOSED')

     Message: Binlog closed, cannot RESET MASTER

   * Error: `1187' SQLSTATE: `HY000' (`ER_INDEX_REBUILD')

     Message: Failed rebuilding the index of dumped table '%s'

   * Error: `1188' SQLSTATE: `HY000' (`ER_MASTER')

     Message: Error from master: '%s'

   * Error: `1189' SQLSTATE: `08S01' (`ER_MASTER_NET_READ')

     Message: Net error reading from master

   * Error: `1190' SQLSTATE: `08S01' (`ER_MASTER_NET_WRITE')

     Message: Net error writing to master

   * Error: `1191' SQLSTATE: `HY000' (`ER_FT_MATCHING_KEY_NOT_FOUND')

     Message: Can't find FULLTEXT index matching the column list

   * Error: `1192' SQLSTATE: `HY000' (`ER_LOCK_OR_ACTIVE_TRANSACTION')

     Message: Can't execute the given command because you have active
     locked tables or an active transaction

   * Error: `1193' SQLSTATE: `HY000' (`ER_UNKNOWN_SYSTEM_VARIABLE')

     Message: Unknown system variable '%s'

   * Error: `1194' SQLSTATE: `HY000' (`ER_CRASHED_ON_USAGE')

     Message: Table '%s' is marked as crashed and should be repaired

   * Error: `1195' SQLSTATE: `HY000' (`ER_CRASHED_ON_REPAIR')

     Message: Table '%s' is marked as crashed and last (automatic?)
     repair failed

   * Error: `1196' SQLSTATE: `HY000'
     (`ER_WARNING_NOT_COMPLETE_ROLLBACK')

     Message: Some non-transactional changed tables couldn't be rolled
     back

   * Error: `1197' SQLSTATE: `HY000' (`ER_TRANS_CACHE_FULL')

     Message: Multi-statement transaction required more than
     'max_binlog_cache_size' bytes of storage; increase this mysqld
     variable and try again

   * Error: `1198' SQLSTATE: `HY000' (`ER_SLAVE_MUST_STOP')

     Message: This operation cannot be performed with a running slave;
     run STOP SLAVE first

   * Error: `1199' SQLSTATE: `HY000' (`ER_SLAVE_NOT_RUNNING')

     Message: This operation requires a running slave; configure slave
     and do START SLAVE

   * Error: `1200' SQLSTATE: `HY000' (`ER_BAD_SLAVE')

     Message: The server is not configured as slave; fix in config file
     or with CHANGE MASTER TO

   * Error: `1201' SQLSTATE: `HY000' (`ER_MASTER_INFO')

     Message: Could not initialize master info structure; more error
     messages can be found in the MySQL error log

   * Error: `1202' SQLSTATE: `HY000' (`ER_SLAVE_THREAD')

     Message: Could not create slave thread; check system resources

   * Error: `1203' SQLSTATE: `42000' (`ER_TOO_MANY_USER_CONNECTIONS')

     Message: User %s already has more than 'max_user_connections'
     active connections

   * Error: `1204' SQLSTATE: `HY000' (`ER_SET_CONSTANTS_ONLY')

     Message: You may only use constant expressions with SET

   * Error: `1205' SQLSTATE: `HY000' (`ER_LOCK_WAIT_TIMEOUT')

     Message: Lock wait timeout exceeded; try restarting transaction

   * Error: `1206' SQLSTATE: `HY000' (`ER_LOCK_TABLE_FULL')

     Message: The total number of locks exceeds the lock table size

   * Error: `1207' SQLSTATE: `25000' (`ER_READ_ONLY_TRANSACTION')

     Message: Update locks cannot be acquired during a READ UNCOMMITTED
     transaction

   * Error: `1208' SQLSTATE: `HY000' (`ER_DROP_DB_WITH_READ_LOCK')

     Message: DROP DATABASE not allowed while thread is holding global
     read lock

   * Error: `1209' SQLSTATE: `HY000' (`ER_CREATE_DB_WITH_READ_LOCK')

     Message: CREATE DATABASE not allowed while thread is holding
     global read lock

   * Error: `1210' SQLSTATE: `HY000' (`ER_WRONG_ARGUMENTS')

     Message: Incorrect arguments to %s

   * Error: `1211' SQLSTATE: `42000' (`ER_NO_PERMISSION_TO_CREATE_USER')

     Message: '%s'@'%s' is not allowed to create new users

   * Error: `1212' SQLSTATE: `HY000'
     (`ER_UNION_TABLES_IN_DIFFERENT_DIR')

     Message: Incorrect table definition; all MERGE tables must be in
     the same database

   * Error: `1213' SQLSTATE: `40001' (`ER_LOCK_DEADLOCK')

     Message: Deadlock found when trying to get lock; try restarting
     transaction

   * Error: `1214' SQLSTATE: `HY000' (`ER_TABLE_CANT_HANDLE_FT')

     Message: The used table type doesn't support FULLTEXT indexes

   * Error: `1215' SQLSTATE: `HY000' (`ER_CANNOT_ADD_FOREIGN')

     Message: Cannot add foreign key constraint

   * Error: `1216' SQLSTATE: `23000' (`ER_NO_REFERENCED_ROW')

     Message: Cannot add or update a child row: a foreign key
     constraint fails

   * Error: `1217' SQLSTATE: `23000' (`ER_ROW_IS_REFERENCED')

     Message: Cannot delete or update a parent row: a foreign key
     constraint fails

   * Error: `1218' SQLSTATE: `08S01' (`ER_CONNECT_TO_MASTER')

     Message: Error connecting to master: %s

   * Error: `1219' SQLSTATE: `HY000' (`ER_QUERY_ON_MASTER')

     Message: Error running query on master: %s

   * Error: `1220' SQLSTATE: `HY000' (`ER_ERROR_WHEN_EXECUTING_COMMAND')

     Message: Error when executing command %s: %s

   * Error: `1221' SQLSTATE: `HY000' (`ER_WRONG_USAGE')

     Message: Incorrect usage of %s and %s

   * Error: `1222' SQLSTATE: `21000'
     (`ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT')

     Message: The used SELECT statements have a different number of
     columns

   * Error: `1223' SQLSTATE: `HY000' (`ER_CANT_UPDATE_WITH_READLOCK')

     Message: Can't execute the query because you have a conflicting
     read lock

   * Error: `1224' SQLSTATE: `HY000' (`ER_MIXING_NOT_ALLOWED')

     Message: Mixing of transactional and non-transactional tables is
     disabled

   * Error: `1225' SQLSTATE: `HY000' (`ER_DUP_ARGUMENT')

     Message: Option '%s' used twice in statement

   * Error: `1226' SQLSTATE: `42000' (`ER_USER_LIMIT_REACHED')

     Message: User '%s' has exceeded the '%s' resource (current value:
     %ld)

   * Error: `1227' SQLSTATE: `42000' (`ER_SPECIFIC_ACCESS_DENIED_ERROR')

     Message: Access denied; you need the %s privilege for this
     operation

   * Error: `1228' SQLSTATE: `HY000' (`ER_LOCAL_VARIABLE')

     Message: Variable '%s' is a SESSION variable and can't be used
     with SET GLOBAL

   * Error: `1229' SQLSTATE: `HY000' (`ER_GLOBAL_VARIABLE')

     Message: Variable '%s' is a GLOBAL variable and should be set with
     SET GLOBAL

   * Error: `1230' SQLSTATE: `42000' (`ER_NO_DEFAULT')

     Message: Variable '%s' doesn't have a default value

   * Error: `1231' SQLSTATE: `42000' (`ER_WRONG_VALUE_FOR_VAR')

     Message: Variable '%s' can't be set to the value of '%s'

   * Error: `1232' SQLSTATE: `42000' (`ER_WRONG_TYPE_FOR_VAR')

     Message: Incorrect argument type to variable '%s'

   * Error: `1233' SQLSTATE: `HY000' (`ER_VAR_CANT_BE_READ')

     Message: Variable '%s' can only be set, not read

   * Error: `1234' SQLSTATE: `42000' (`ER_CANT_USE_OPTION_HERE')

     Message: Incorrect usage/placement of '%s'

   * Error: `1235' SQLSTATE: `42000' (`ER_NOT_SUPPORTED_YET')

     Message: This version of MySQL doesn't yet support '%s'

   * Error: `1236' SQLSTATE: `HY000'
     (`ER_MASTER_FATAL_ERROR_READING_BINLOG')

     Message: Got fatal error %d: '%s' from master when reading data
     from binary log

   * Error: `1237' SQLSTATE: `HY000' (`ER_SLAVE_IGNORED_TABLE')

     Message: Slave SQL thread ignored the query because of
     replicate-*-table rules

   * Error: `1238' SQLSTATE: `HY000' (`ER_INCORRECT_GLOBAL_LOCAL_VAR')

     Message: Variable '%s' is a %s variable

   * Error: `1239' SQLSTATE: `42000' (`ER_WRONG_FK_DEF')

     Message: Incorrect foreign key definition for '%s': %s

   * Error: `1240' SQLSTATE: `HY000'
     (`ER_KEY_REF_DO_NOT_MATCH_TABLE_REF')

     Message: Key reference and table reference don't match

   * Error: `1241' SQLSTATE: `21000' (`ER_OPERAND_COLUMNS')

     Message: Operand should contain %d column(s)

   * Error: `1242' SQLSTATE: `21000' (`ER_SUBQUERY_NO_1_ROW')

     Message: Subquery returns more than 1 row

   * Error: `1243' SQLSTATE: `HY000' (`ER_UNKNOWN_STMT_HANDLER')

     Message: Unknown prepared statement handler (%.*s) given to %s

   * Error: `1244' SQLSTATE: `HY000' (`ER_CORRUPT_HELP_DB')

     Message: Help database is corrupt or does not exist

   * Error: `1245' SQLSTATE: `HY000' (`ER_CYCLIC_REFERENCE')

     Message: Cyclic reference on subqueries

   * Error: `1246' SQLSTATE: `HY000' (`ER_AUTO_CONVERT')

     Message: Converting column '%s' from %s to %s

   * Error: `1247' SQLSTATE: `42S22' (`ER_ILLEGAL_REFERENCE')

     Message: Reference '%s' not supported (%s)

   * Error: `1248' SQLSTATE: `42000' (`ER_DERIVED_MUST_HAVE_ALIAS')

     Message: Every derived table must have its own alias

   * Error: `1249' SQLSTATE: `01000' (`ER_SELECT_REDUCED')

     Message: Select %u was reduced during optimization

   * Error: `1250' SQLSTATE: `42000' (`ER_TABLENAME_NOT_ALLOWED_HERE')

     Message: Table '%s' from one of the SELECTs cannot be used in %s

   * Error: `1251' SQLSTATE: `08004' (`ER_NOT_SUPPORTED_AUTH_MODE')

     Message: Client does not support authentication protocol requested
     by server; consider upgrading MySQL client

   * Error: `1252' SQLSTATE: `42000' (`ER_SPATIAL_CANT_HAVE_NULL')

     Message: All parts of a SPATIAL index must be NOT NULL

   * Error: `1253' SQLSTATE: `42000' (`ER_COLLATION_CHARSET_MISMATCH')

     Message: COLLATION '%s' is not valid for CHARACTER SET '%s'

   * Error: `1254' SQLSTATE: `HY000' (`ER_SLAVE_WAS_RUNNING')

     Message: Slave is already running

   * Error: `1255' SQLSTATE: `HY000' (`ER_SLAVE_WAS_NOT_RUNNING')

     Message: Slave already has been stopped

   * Error: `1256' SQLSTATE: `HY000' (`ER_TOO_BIG_FOR_UNCOMPRESS')

     Message: Uncompressed data size too large; the maximum size is %d
     (probably, length of uncompressed data was corrupted)

   * Error: `1257' SQLSTATE: `HY000' (`ER_ZLIB_Z_MEM_ERROR')

     Message: ZLIB: Not enough memory

   * Error: `1258' SQLSTATE: `HY000' (`ER_ZLIB_Z_BUF_ERROR')

     Message: ZLIB: Not enough room in the output buffer (probably,
     length of uncompressed data was corrupted)

   * Error: `1259' SQLSTATE: `HY000' (`ER_ZLIB_Z_DATA_ERROR')

     Message: ZLIB: Input data corrupted

   * Error: `1260' SQLSTATE: `HY000' (`ER_CUT_VALUE_GROUP_CONCAT')

     Message: %d line(s) were cut by GROUP_CONCAT()

   * Error: `1261' SQLSTATE: `01000' (`ER_WARN_TOO_FEW_RECORDS')

     Message: Row %ld doesn't contain data for all columns

   * Error: `1262' SQLSTATE: `01000' (`ER_WARN_TOO_MANY_RECORDS')

     Message: Row %ld was truncated; it contained more data than there
     were input columns

   * Error: `1263' SQLSTATE: `22004' (`ER_WARN_NULL_TO_NOTNULL')

     Message: Column set to default value; NULL supplied to NOT NULL
     column '%s' at row %ld

   * Error: `1264' SQLSTATE: `22003' (`ER_WARN_DATA_OUT_OF_RANGE')

     Message: Out of range value for column '%s' at row %ld

   * Error: `1265' SQLSTATE: `01000' (`WARN_DATA_TRUNCATED')

     Message: Data truncated for column '%s' at row %ld

   * Error: `1266' SQLSTATE: `HY000' (`ER_WARN_USING_OTHER_HANDLER')

     Message: Using storage engine %s for table '%s'

   * Error: `1267' SQLSTATE: `HY000' (`ER_CANT_AGGREGATE_2COLLATIONS')

     Message: Illegal mix of collations (%s,%s) and (%s,%s) for
     operation '%s'

   * Error: `1268' SQLSTATE: `HY000' (`ER_DROP_USER')

     Message: Cannot drop one or more of the requested users

   * Error: `1269' SQLSTATE: `HY000' (`ER_REVOKE_GRANTS')

     Message: Can't revoke all privileges for one or more of the
     requested users

   * Error: `1270' SQLSTATE: `HY000' (`ER_CANT_AGGREGATE_3COLLATIONS')

     Message: Illegal mix of collations (%s,%s), (%s,%s), (%s,%s) for
     operation '%s'

   * Error: `1271' SQLSTATE: `HY000' (`ER_CANT_AGGREGATE_NCOLLATIONS')

     Message: Illegal mix of collations for operation '%s'

   * Error: `1272' SQLSTATE: `HY000' (`ER_VARIABLE_IS_NOT_STRUCT')

     Message: Variable '%s' is not a variable component (can't be used
     as XXXX.variable_name)

   * Error: `1273' SQLSTATE: `HY000' (`ER_UNKNOWN_COLLATION')

     Message: Unknown collation: '%s'

   * Error: `1274' SQLSTATE: `HY000' (`ER_SLAVE_IGNORED_SSL_PARAMS')

     Message: SSL parameters in CHANGE MASTER are ignored because this
     MySQL slave was compiled without SSL support; they can be used
     later if MySQL slave with SSL is started

   * Error: `1275' SQLSTATE: `HY000'
     (`ER_SERVER_IS_IN_SECURE_AUTH_MODE')

     Message: Server is running in -secure-auth mode, but '%s'@'%s' has
     a password in the old format; please change the password to the
     new format

   * Error: `1276' SQLSTATE: `HY000' (`ER_WARN_FIELD_RESOLVED')

     Message: Field or reference '%s%s%s%s%s' of SELECT #%d was
     resolved in SELECT #%d

   * Error: `1277' SQLSTATE: `HY000' (`ER_BAD_SLAVE_UNTIL_COND')

     Message: Incorrect parameter or combination of parameters for
     START SLAVE UNTIL

   * Error: `1278' SQLSTATE: `HY000' (`ER_MISSING_SKIP_SLAVE')

     Message: It is recommended to use -skip-slave-start when doing
     step-by-step replication with START SLAVE UNTIL; otherwise, you
     will get problems if you get an unexpected slave's mysqld restart

   * Error: `1279' SQLSTATE: `HY000' (`ER_UNTIL_COND_IGNORED')

     Message: SQL thread is not to be started so UNTIL options are
     ignored

   * Error: `1280' SQLSTATE: `42000' (`ER_WRONG_NAME_FOR_INDEX')

     Message: Incorrect index name '%s'

   * Error: `1281' SQLSTATE: `42000' (`ER_WRONG_NAME_FOR_CATALOG')

     Message: Incorrect catalog name '%s'

   * Error: `1282' SQLSTATE: `HY000' (`ER_WARN_QC_RESIZE')

     Message: Query cache failed to set size %lu; new query cache size
     is %lu

   * Error: `1283' SQLSTATE: `HY000' (`ER_BAD_FT_COLUMN')

     Message: Column '%s' cannot be part of FULLTEXT index

   * Error: `1284' SQLSTATE: `HY000' (`ER_UNKNOWN_KEY_CACHE')

     Message: Unknown key cache '%s'

   * Error: `1285' SQLSTATE: `HY000' (`ER_WARN_HOSTNAME_WONT_WORK')

     Message: MySQL is started in -skip-name-resolve mode; you must
     restart it without this switch for this grant to work

   * Error: `1286' SQLSTATE: `42000' (`ER_UNKNOWN_STORAGE_ENGINE')

     Message: Unknown table engine '%s'

   * Error: `1287' SQLSTATE: `HY000' (`ER_WARN_DEPRECATED_SYNTAX')

     Message: '%s' is deprecated; use '%s' instead

   * Error: `1288' SQLSTATE: `HY000' (`ER_NON_UPDATABLE_TABLE')

     Message: The target table %s of the %s is not updatable

   * Error: `1289' SQLSTATE: `HY000' (`ER_FEATURE_DISABLED')

     Message: The '%s' feature is disabled; you need MySQL built with
     '%s' to have it working

   * Error: `1290' SQLSTATE: `HY000' (`ER_OPTION_PREVENTS_STATEMENT')

     Message: The MySQL server is running with the %s option so it
     cannot execute this statement

   * Error: `1291' SQLSTATE: `HY000' (`ER_DUPLICATED_VALUE_IN_TYPE')

     Message: Column '%s' has duplicated value '%s' in %s

   * Error: `1292' SQLSTATE: `22007' (`ER_TRUNCATED_WRONG_VALUE')

     Message: Truncated incorrect %s value: '%s'

   * Error: `1293' SQLSTATE: `HY000' (`ER_TOO_MUCH_AUTO_TIMESTAMP_COLS')

     Message: Incorrect table definition; there can be only one
     TIMESTAMP column with CURRENT_TIMESTAMP in DEFAULT or ON UPDATE
     clause

   * Error: `1294' SQLSTATE: `HY000' (`ER_INVALID_ON_UPDATE')

     Message: Invalid ON UPDATE clause for '%s' column

   * Error: `1295' SQLSTATE: `HY000' (`ER_UNSUPPORTED_PS')

     Message: This command is not supported in the prepared statement
     protocol yet

   * Error: `1296' SQLSTATE: `HY000' (`ER_GET_ERRMSG')

     Message: Got error %d '%s' from %s

   * Error: `1297' SQLSTATE: `HY000' (`ER_GET_TEMPORARY_ERRMSG')

     Message: Got temporary error %d '%s' from %s

   * Error: `1298' SQLSTATE: `HY000' (`ER_UNKNOWN_TIME_ZONE')

     Message: Unknown or incorrect time zone: '%s'

   * Error: `1299' SQLSTATE: `HY000' (`ER_WARN_INVALID_TIMESTAMP')

     Message: Invalid TIMESTAMP value in column '%s' at row %ld

   * Error: `1300' SQLSTATE: `HY000' (`ER_INVALID_CHARACTER_STRING')

     Message: Invalid %s character string: '%s'

   * Error: `1301' SQLSTATE: `HY000'
     (`ER_WARN_ALLOWED_PACKET_OVERFLOWED')

     Message: Result of %s() was larger than max_allowed_packet (%ld) -
     truncated

   * Error: `1302' SQLSTATE: `HY000' (`ER_CONFLICTING_DECLARATIONS')

     Message: Conflicting declarations: '%s%s' and '%s%s'

   * Error: `1303' SQLSTATE: `2F003' (`ER_SP_NO_RECURSIVE_CREATE')

     Message: Can't create a %s from within another stored routine

   * Error: `1304' SQLSTATE: `42000' (`ER_SP_ALREADY_EXISTS')

     Message: %s %s already exists

   * Error: `1305' SQLSTATE: `42000' (`ER_SP_DOES_NOT_EXIST')

     Message: %s %s does not exist

   * Error: `1306' SQLSTATE: `HY000' (`ER_SP_DROP_FAILED')

     Message: Failed to DROP %s %s

   * Error: `1307' SQLSTATE: `HY000' (`ER_SP_STORE_FAILED')

     Message: Failed to CREATE %s %s

   * Error: `1308' SQLSTATE: `42000' (`ER_SP_LILABEL_MISMATCH')

     Message: %s with no matching label: %s

   * Error: `1309' SQLSTATE: `42000' (`ER_SP_LABEL_REDEFINE')

     Message: Redefining label %s

   * Error: `1310' SQLSTATE: `42000' (`ER_SP_LABEL_MISMATCH')

     Message: End-label %s without match

   * Error: `1311' SQLSTATE: `01000' (`ER_SP_UNINIT_VAR')

     Message: Referring to uninitialized variable %s

   * Error: `1312' SQLSTATE: `0A000' (`ER_SP_BADSELECT')

     Message: PROCEDURE %s can't return a result set in the given
     context

   * Error: `1313' SQLSTATE: `42000' (`ER_SP_BADRETURN')

     Message: RETURN is only allowed in a FUNCTION

   * Error: `1314' SQLSTATE: `0A000' (`ER_SP_BADSTATEMENT')

     Message: %s is not allowed in stored procedures

   * Error: `1315' SQLSTATE: `42000'
     (`ER_UPDATE_LOG_DEPRECATED_IGNORED')

     Message: The update log is deprecated and replaced by the binary
     log; SET SQL_LOG_UPDATE has been ignored

   * Error: `1316' SQLSTATE: `42000'
     (`ER_UPDATE_LOG_DEPRECATED_TRANSLATED')

     Message: The update log is deprecated and replaced by the binary
     log; SET SQL_LOG_UPDATE has been translated to SET SQL_LOG_BIN

   * Error: `1317' SQLSTATE: `70100' (`ER_QUERY_INTERRUPTED')

     Message: Query execution was interrupted

   * Error: `1318' SQLSTATE: `42000' (`ER_SP_WRONG_NO_OF_ARGS')

     Message: Incorrect number of arguments for %s %s; expected %u, got
     %u

   * Error: `1319' SQLSTATE: `42000' (`ER_SP_COND_MISMATCH')

     Message: Undefined CONDITION: %s

   * Error: `1320' SQLSTATE: `42000' (`ER_SP_NORETURN')

     Message: No RETURN found in FUNCTION %s

   * Error: `1321' SQLSTATE: `2F005' (`ER_SP_NORETURNEND')

     Message: FUNCTION %s ended without RETURN

   * Error: `1322' SQLSTATE: `42000' (`ER_SP_BAD_CURSOR_QUERY')

     Message: Cursor statement must be a SELECT

   * Error: `1323' SQLSTATE: `42000' (`ER_SP_BAD_CURSOR_SELECT')

     Message: Cursor SELECT must not have INTO

   * Error: `1324' SQLSTATE: `42000' (`ER_SP_CURSOR_MISMATCH')

     Message: Undefined CURSOR: %s

   * Error: `1325' SQLSTATE: `24000' (`ER_SP_CURSOR_ALREADY_OPEN')

     Message: Cursor is already open

   * Error: `1326' SQLSTATE: `24000' (`ER_SP_CURSOR_NOT_OPEN')

     Message: Cursor is not open

   * Error: `1327' SQLSTATE: `42000' (`ER_SP_UNDECLARED_VAR')

     Message: Undeclared variable: %s

   * Error: `1328' SQLSTATE: `HY000' (`ER_SP_WRONG_NO_OF_FETCH_ARGS')

     Message: Incorrect number of FETCH variables

   * Error: `1329' SQLSTATE: `02000' (`ER_SP_FETCH_NO_DATA')

     Message: No data - zero rows fetched, selected, or processed

   * Error: `1330' SQLSTATE: `42000' (`ER_SP_DUP_PARAM')

     Message: Duplicate parameter: %s

   * Error: `1331' SQLSTATE: `42000' (`ER_SP_DUP_VAR')

     Message: Duplicate variable: %s

   * Error: `1332' SQLSTATE: `42000' (`ER_SP_DUP_COND')

     Message: Duplicate condition: %s

   * Error: `1333' SQLSTATE: `42000' (`ER_SP_DUP_CURS')

     Message: Duplicate cursor: %s

   * Error: `1334' SQLSTATE: `HY000' (`ER_SP_CANT_ALTER')

     Message: Failed to ALTER %s %s

   * Error: `1335' SQLSTATE: `0A000' (`ER_SP_SUBSELECT_NYI')

     Message: Subquery value not supported

   * Error: `1336' SQLSTATE: `0A000'
     (`ER_STMT_NOT_ALLOWED_IN_SF_OR_TRG')

     Message: %s is not allowed in stored function or trigger

   * Error: `1337' SQLSTATE: `42000' (`ER_SP_VARCOND_AFTER_CURSHNDLR')

     Message: Variable or condition declaration after cursor or handler
     declaration

   * Error: `1338' SQLSTATE: `42000' (`ER_SP_CURSOR_AFTER_HANDLER')

     Message: Cursor declaration after handler declaration

   * Error: `1339' SQLSTATE: `20000' (`ER_SP_CASE_NOT_FOUND')

     Message: Case not found for CASE statement

   * Error: `1340' SQLSTATE: `HY000' (`ER_FPARSER_TOO_BIG_FILE')

     Message: Configuration file '%s' is too big

   * Error: `1341' SQLSTATE: `HY000' (`ER_FPARSER_BAD_HEADER')

     Message: Malformed file type header in file '%s'

   * Error: `1342' SQLSTATE: `HY000' (`ER_FPARSER_EOF_IN_COMMENT')

     Message: Unexpected end of file while parsing comment '%s'

   * Error: `1343' SQLSTATE: `HY000' (`ER_FPARSER_ERROR_IN_PARAMETER')

     Message: Error while parsing parameter '%s' (line: '%s')

   * Error: `1344' SQLSTATE: `HY000'
     (`ER_FPARSER_EOF_IN_UNKNOWN_PARAMETER')

     Message: Unexpected end of file while skipping unknown parameter
     '%s'

   * Error: `1345' SQLSTATE: `HY000' (`ER_VIEW_NO_EXPLAIN')

     Message: EXPLAIN/SHOW can not be issued; lacking privileges for
     underlying table

   * Error: `1346' SQLSTATE: `HY000' (`ER_FRM_UNKNOWN_TYPE')

     Message: File '%s' has unknown type '%s' in its header

   * Error: `1347' SQLSTATE: `HY000' (`ER_WRONG_OBJECT')

     Message: '%s.%s' is not %s

   * Error: `1348' SQLSTATE: `HY000' (`ER_NONUPDATEABLE_COLUMN')

     Message: Column '%s' is not updatable

   * Error: `1349' SQLSTATE: `HY000' (`ER_VIEW_SELECT_DERIVED')

     Message: View's SELECT contains a subquery in the FROM clause

   * Error: `1350' SQLSTATE: `HY000' (`ER_VIEW_SELECT_CLAUSE')

     Message: View's SELECT contains a '%s' clause

   * Error: `1351' SQLSTATE: `HY000' (`ER_VIEW_SELECT_VARIABLE')

     Message: View's SELECT contains a variable or parameter

   * Error: `1352' SQLSTATE: `HY000' (`ER_VIEW_SELECT_TMPTABLE')

     Message: View's SELECT refers to a temporary table '%s'

   * Error: `1353' SQLSTATE: `HY000' (`ER_VIEW_WRONG_LIST')

     Message: View's SELECT and view's field list have different column
     counts

   * Error: `1354' SQLSTATE: `HY000' (`ER_WARN_VIEW_MERGE')

     Message: View merge algorithm can't be used here for now (assumed
     undefined algorithm)

   * Error: `1355' SQLSTATE: `HY000' (`ER_WARN_VIEW_WITHOUT_KEY')

     Message: View being updated does not have complete key of
     underlying table in it

   * Error: `1356' SQLSTATE: `HY000' (`ER_VIEW_INVALID')

     Message: View '%s.%s' references invalid table(s) or column(s) or
     function(s) or definer/invoker of view lack rights to use them

   * Error: `1357' SQLSTATE: `HY000' (`ER_SP_NO_DROP_SP')

     Message: Can't drop or alter a %s from within another stored
     routine

   * Error: `1358' SQLSTATE: `HY000' (`ER_SP_GOTO_IN_HNDLR')

     Message: GOTO is not allowed in a stored procedure handler

   * Error: `1359' SQLSTATE: `HY000' (`ER_TRG_ALREADY_EXISTS')

     Message: Trigger already exists

   * Error: `1360' SQLSTATE: `HY000' (`ER_TRG_DOES_NOT_EXIST')

     Message: Trigger does not exist

   * Error: `1361' SQLSTATE: `HY000' (`ER_TRG_ON_VIEW_OR_TEMP_TABLE')

     Message: Trigger's '%s' is view or temporary table

   * Error: `1362' SQLSTATE: `HY000' (`ER_TRG_CANT_CHANGE_ROW')

     Message: Updating of %s row is not allowed in %strigger

   * Error: `1363' SQLSTATE: `HY000' (`ER_TRG_NO_SUCH_ROW_IN_TRG')

     Message: There is no %s row in %s trigger

   * Error: `1364' SQLSTATE: `HY000' (`ER_NO_DEFAULT_FOR_FIELD')

     Message: Field '%s' doesn't have a default value

   * Error: `1365' SQLSTATE: `22012' (`ER_DIVISION_BY_ZERO')

     Message: Division by 0

   * Error: `1366' SQLSTATE: `HY000'
     (`ER_TRUNCATED_WRONG_VALUE_FOR_FIELD')

     Message: Incorrect %s value: '%s' for column '%s' at row %ld

   * Error: `1367' SQLSTATE: `22007' (`ER_ILLEGAL_VALUE_FOR_TYPE')

     Message: Illegal %s '%s' value found during parsing

   * Error: `1368' SQLSTATE: `HY000' (`ER_VIEW_NONUPD_CHECK')

     Message: CHECK OPTION on non-updatable view '%s.%s'

   * Error: `1369' SQLSTATE: `HY000' (`ER_VIEW_CHECK_FAILED')

     Message: CHECK OPTION failed '%s.%s'

   * Error: `1370' SQLSTATE: `42000' (`ER_PROCACCESS_DENIED_ERROR')

     Message: %s command denied to user '%s'@'%s' for routine '%s'

   * Error: `1371' SQLSTATE: `HY000' (`ER_RELAY_LOG_FAIL')

     Message: Failed purging old relay logs: %s

   * Error: `1372' SQLSTATE: `HY000' (`ER_PASSWD_LENGTH')

     Message: Password hash should be a %d-digit hexadecimal number

   * Error: `1373' SQLSTATE: `HY000' (`ER_UNKNOWN_TARGET_BINLOG')

     Message: Target log not found in binlog index

   * Error: `1374' SQLSTATE: `HY000' (`ER_IO_ERR_LOG_INDEX_READ')

     Message: I/O error reading log index file

   * Error: `1375' SQLSTATE: `HY000' (`ER_BINLOG_PURGE_PROHIBITED')

     Message: Server configuration does not permit binlog purge

   * Error: `1376' SQLSTATE: `HY000' (`ER_FSEEK_FAIL')

     Message: Failed on fseek()

   * Error: `1377' SQLSTATE: `HY000' (`ER_BINLOG_PURGE_FATAL_ERR')

     Message: Fatal error during log purge

   * Error: `1378' SQLSTATE: `HY000' (`ER_LOG_IN_USE')

     Message: A purgeable log is in use, will not purge

   * Error: `1379' SQLSTATE: `HY000' (`ER_LOG_PURGE_UNKNOWN_ERR')

     Message: Unknown error during log purge

   * Error: `1380' SQLSTATE: `HY000' (`ER_RELAY_LOG_INIT')

     Message: Failed initializing relay log position: %s

   * Error: `1381' SQLSTATE: `HY000' (`ER_NO_BINARY_LOGGING')

     Message: You are not using binary logging

   * Error: `1382' SQLSTATE: `HY000' (`ER_RESERVED_SYNTAX')

     Message: The '%s' syntax is reserved for purposes internal to the
     MySQL server

   * Error: `1383' SQLSTATE: `HY000' (`ER_WSAS_FAILED')

     Message: WSAStartup Failed

   * Error: `1384' SQLSTATE: `HY000' (`ER_DIFF_GROUPS_PROC')

     Message: Can't handle procedures with different groups yet

   * Error: `1385' SQLSTATE: `HY000' (`ER_NO_GROUP_FOR_PROC')

     Message: Select must have a group with this procedure

   * Error: `1386' SQLSTATE: `HY000' (`ER_ORDER_WITH_PROC')

     Message: Can't use ORDER clause with this procedure

   * Error: `1387' SQLSTATE: `HY000' (`ER_LOGGING_PROHIBIT_CHANGING_OF')

     Message: Binary logging and replication forbid changing the global
     server %s

   * Error: `1388' SQLSTATE: `HY000' (`ER_NO_FILE_MAPPING')

     Message: Can't map file: %s, errno: %d

   * Error: `1389' SQLSTATE: `HY000' (`ER_WRONG_MAGIC')

     Message: Wrong magic in %s

   * Error: `1390' SQLSTATE: `HY000' (`ER_PS_MANY_PARAM')

     Message: Prepared statement contains too many placeholders

   * Error: `1391' SQLSTATE: `HY000' (`ER_KEY_PART_0')

     Message: Key part '%s' length cannot be 0

   * Error: `1392' SQLSTATE: `HY000' (`ER_VIEW_CHECKSUM')

     Message: View text checksum failed

   * Error: `1393' SQLSTATE: `HY000' (`ER_VIEW_MULTIUPDATE')

     Message: Can not modify more than one base table through a join
     view '%s.%s'

   * Error: `1394' SQLSTATE: `HY000' (`ER_VIEW_NO_INSERT_FIELD_LIST')

     Message: Can not insert into join view '%s.%s' without fields list

   * Error: `1395' SQLSTATE: `HY000' (`ER_VIEW_DELETE_MERGE_VIEW')

     Message: Can not delete from join view '%s.%s'

   * Error: `1396' SQLSTATE: `HY000' (`ER_CANNOT_USER')

     Message: Operation %s failed for %s

   * Error: `1397' SQLSTATE: `XAE04' (`ER_XAER_NOTA')

     Message: XAER_NOTA: Unknown XID

   * Error: `1398' SQLSTATE: `XAE05' (`ER_XAER_INVAL')

     Message: XAER_INVAL: Invalid arguments (or unsupported command)

   * Error: `1399' SQLSTATE: `XAE07' (`ER_XAER_RMFAIL')

     Message: XAER_RMFAIL: The command cannot be executed when global
     transaction is in the %s state

   * Error: `1400' SQLSTATE: `XAE09' (`ER_XAER_OUTSIDE')

     Message: XAER_OUTSIDE: Some work is done outside global transaction

   * Error: `1401' SQLSTATE: `XAE03' (`ER_XAER_RMERR')

     Message: XAER_RMERR: Fatal error occurred in the transaction
     branch - check your data for consistency

   * Error: `1402' SQLSTATE: `XA100' (`ER_XA_RBROLLBACK')

     Message: XA_RBROLLBACK: Transaction branch was rolled back

   * Error: `1403' SQLSTATE: `42000' (`ER_NONEXISTING_PROC_GRANT')

     Message: There is no such grant defined for user '%s' on host '%s'
     on routine '%s'

   * Error: `1404' SQLSTATE: `HY000' (`ER_PROC_AUTO_GRANT_FAIL')

     Message: Failed to grant EXECUTE and ALTER ROUTINE privileges

   * Error: `1405' SQLSTATE: `HY000' (`ER_PROC_AUTO_REVOKE_FAIL')

     Message: Failed to revoke all privileges to dropped routine

   * Error: `1406' SQLSTATE: `22001' (`ER_DATA_TOO_LONG')

     Message: Data too long for column '%s' at row %ld

   * Error: `1407' SQLSTATE: `42000' (`ER_SP_BAD_SQLSTATE')

     Message: Bad SQLSTATE: '%s'

   * Error: `1408' SQLSTATE: `HY000' (`ER_STARTUP')

     Message: %s: ready for connections. Version: '%s' socket: '%s'
     port: %d %s

   * Error: `1409' SQLSTATE: `HY000'
     (`ER_LOAD_FROM_FIXED_SIZE_ROWS_TO_VAR')

     Message: Can't load value from file with fixed size rows to
     variable

   * Error: `1410' SQLSTATE: `42000' (`ER_CANT_CREATE_USER_WITH_GRANT')

     Message: You are not allowed to create a user with GRANT

   * Error: `1411' SQLSTATE: `HY000' (`ER_WRONG_VALUE_FOR_TYPE')

     Message: Incorrect %s value: '%s' for function %s

   * Error: `1412' SQLSTATE: `HY000' (`ER_TABLE_DEF_CHANGED')

     Message: Table definition has changed, please retry transaction

   * Error: `1413' SQLSTATE: `42000' (`ER_SP_DUP_HANDLER')

     Message: Duplicate handler declared in the same block

   * Error: `1414' SQLSTATE: `42000' (`ER_SP_NOT_VAR_ARG')

     Message: OUT or INOUT argument %d for routine %s is not a variable
     or NEW pseudo-variable in BEFORE trigger

   * Error: `1415' SQLSTATE: `0A000' (`ER_SP_NO_RETSET')

     Message: Not allowed to return a result set from a %s

   * Error: `1416' SQLSTATE: `22003' (`ER_CANT_CREATE_GEOMETRY_OBJECT')

     Message: Cannot get geometry object from data you send to the
     GEOMETRY field

   * Error: `1417' SQLSTATE: `HY000' (`ER_FAILED_ROUTINE_BREAK_BINLOG')

     Message: A routine failed and has neither NO SQL nor READS SQL
     DATA in its declaration and binary logging is enabled; if
     non-transactional tables were updated, the binary log will miss
     their changes

   * Error: `1418' SQLSTATE: `HY000' (`ER_BINLOG_UNSAFE_ROUTINE')

     Message: This function has none of DETERMINISTIC, NO SQL, or READS
     SQL DATA in its declaration and binary logging is enabled (you
     *might* want to use the less safe log_bin_trust_function_creators
     variable)

   * Error: `1419' SQLSTATE: `HY000'
     (`ER_BINLOG_CREATE_ROUTINE_NEED_SUPER')

     Message: You do not have the SUPER privilege and binary logging is
     enabled (you *might* want to use the less safe
     log_bin_trust_function_creators variable)

   * Error: `1420' SQLSTATE: `HY000' (`ER_EXEC_STMT_WITH_OPEN_CURSOR')

     Message: You can't execute a prepared statement which has an open
     cursor associated with it. Reset the statement to re-execute it.

   * Error: `1421' SQLSTATE: `HY000' (`ER_STMT_HAS_NO_OPEN_CURSOR')

     Message: The statement (%lu) has no open cursor.

   * Error: `1422' SQLSTATE: `HY000'
     (`ER_COMMIT_NOT_ALLOWED_IN_SF_OR_TRG')

     Message: Explicit or implicit commit is not allowed in stored
     function or trigger.

   * Error: `1423' SQLSTATE: `HY000' (`ER_NO_DEFAULT_FOR_VIEW_FIELD')

     Message: Field of view '%s.%s' underlying table doesn't have a
     default value

   * Error: `1424' SQLSTATE: `HY000' (`ER_SP_NO_RECURSION')

     Message: Recursive stored functions and triggers are not allowed.

   * Error: `1425' SQLSTATE: `42000' (`ER_TOO_BIG_SCALE')

     Message: Too big scale %d specified for column '%s'. Maximum is
     %lu.

   * Error: `1426' SQLSTATE: `42000' (`ER_TOO_BIG_PRECISION')

     Message: Too big precision %d specified for column '%s'. Maximum
     is %lu.

   * Error: `1427' SQLSTATE: `42000' (`ER_M_BIGGER_THAN_D')

     Message: For float(M,D), double(M,D) or decimal(M,D), M must be >=
     D (column '%s').

   * Error: `1428' SQLSTATE: `HY000' (`ER_WRONG_LOCK_OF_SYSTEM_TABLE')

     Message: You can't combine write-locking of system tables with
     other tables or lock types

   * Error: `1429' SQLSTATE: `HY000'
     (`ER_CONNECT_TO_FOREIGN_DATA_SOURCE')

     Message: Unable to connect to foreign data source: %s

   * Error: `1430' SQLSTATE: `HY000' (`ER_QUERY_ON_FOREIGN_DATA_SOURCE')

     Message: There was a problem processing the query on the foreign
     data source. Data source error: %s

   * Error: `1431' SQLSTATE: `HY000'
     (`ER_FOREIGN_DATA_SOURCE_DOESNT_EXIST')

     Message: The foreign data source you are trying to reference does
     not exist. Data source error: %s

   * Error: `1432' SQLSTATE: `HY000'
     (`ER_FOREIGN_DATA_STRING_INVALID_CANT_CREATE')

     Message: Can't create federated table. The data source connection
     string '%s' is not in the correct format

   * Error: `1433' SQLSTATE: `HY000' (`ER_FOREIGN_DATA_STRING_INVALID')

     Message: The data source connection string '%s' is not in the
     correct format

   * Error: `1434' SQLSTATE: `HY000' (`ER_CANT_CREATE_FEDERATED_TABLE')

     Message: Can't create federated table. Foreign data src error: %s

   * Error: `1435' SQLSTATE: `HY000' (`ER_TRG_IN_WRONG_SCHEMA')

     Message: Trigger in wrong schema

   * Error: `1436' SQLSTATE: `HY000' (`ER_STACK_OVERRUN_NEED_MORE')

     Message: Thread stack overrun: %ld bytes used of a %ld byte stack,
     and %ld bytes needed. Use 'mysqld -O thread_stack=#' to specify a
     bigger stack.

   * Error: `1437' SQLSTATE: `42000' (`ER_TOO_LONG_BODY')

     Message: Routine body for '%s' is too long

   * Error: `1438' SQLSTATE: `HY000'
     (`ER_WARN_CANT_DROP_DEFAULT_KEYCACHE')

     Message: Cannot drop default keycache

   * Error: `1439' SQLSTATE: `42000' (`ER_TOO_BIG_DISPLAYWIDTH')

     Message: Display width out of range for column '%s' (max = %lu)

   * Error: `1440' SQLSTATE: `XAE08' (`ER_XAER_DUPID')

     Message: XAER_DUPID: The XID already exists

   * Error: `1441' SQLSTATE: `22008' (`ER_DATETIME_FUNCTION_OVERFLOW')

     Message: Datetime function: %s field overflow

   * Error: `1442' SQLSTATE: `HY000'
     (`ER_CANT_UPDATE_USED_TABLE_IN_SF_OR_TRG')

     Message: Can't update table '%s' in stored function/trigger
     because it is already used by statement which invoked this stored
     function/trigger.

   * Error: `1443' SQLSTATE: `HY000' (`ER_VIEW_PREVENT_UPDATE')

     Message: The definition of table '%s' prevents operation %s on
     table '%s'.

   * Error: `1444' SQLSTATE: `HY000' (`ER_PS_NO_RECURSION')

     Message: The prepared statement contains a stored routine call
     that refers to that same statement. It's not allowed to execute a
     prepared statement in such a recursive manner

   * Error: `1445' SQLSTATE: `HY000' (`ER_SP_CANT_SET_AUTOCOMMIT')

     Message: Not allowed to set autocommit from a stored function or
     trigger

   * Error: `1446' SQLSTATE: `HY000' (`ER_MALFORMED_DEFINER')

     Message: Definer is not fully qualified

   * Error: `1447' SQLSTATE: `HY000' (`ER_VIEW_FRM_NO_USER')

     Message: View '%s'.'%s' has no definer information (old table
     format). Current user is used as definer. Please recreate the view!

   * Error: `1448' SQLSTATE: `HY000' (`ER_VIEW_OTHER_USER')

     Message: You need the SUPER privilege for creation view with
     '%s'@'%s' definer

   * Error: `1449' SQLSTATE: `HY000' (`ER_NO_SUCH_USER')

     Message: The user specified as a definer ('%s'@'%s') does not exist

   * Error: `1450' SQLSTATE: `HY000' (`ER_FORBID_SCHEMA_CHANGE')

     Message: Changing schema from '%s' to '%s' is not allowed.

   * Error: `1451' SQLSTATE: `23000' (`ER_ROW_IS_REFERENCED_2')

     Message: Cannot delete or update a parent row: a foreign key
     constraint fails (%s)

   * Error: `1452' SQLSTATE: `23000' (`ER_NO_REFERENCED_ROW_2')

     Message: Cannot add or update a child row: a foreign key
     constraint fails (%s)

   * Error: `1453' SQLSTATE: `42000' (`ER_SP_BAD_VAR_SHADOW')

     Message: Variable '%s' must be quoted with `...`, or renamed

   * Error: `1454' SQLSTATE: `HY000' (`ER_TRG_NO_DEFINER')

     Message: No definer attribute for trigger '%s'.'%s'. The trigger
     will be activated under the authorization of the invoker, which
     may have insufficient privileges. Please recreate the trigger.

   * Error: `1455' SQLSTATE: `HY000' (`ER_OLD_FILE_FORMAT')

     Message: '%s' has an old format, you should re-create the '%s'
     object(s)

   * Error: `1456' SQLSTATE: `HY000' (`ER_SP_RECURSION_LIMIT')

     Message: Recursive limit %d (as set by the max_sp_recursion_depth
     variable) was exceeded for routine %s

   * Error: `1457' SQLSTATE: `HY000' (`ER_SP_PROC_TABLE_CORRUPT')

     Message: Failed to load routine %s. The table mysql.proc is
     missing, corrupt, or contains bad data (internal code %d)

   * Error: `1458' SQLSTATE: `42000' (`ER_SP_WRONG_NAME')

     Message: Incorrect routine name '%s'

   * Error: `1459' SQLSTATE: `HY000' (`ER_TABLE_NEEDS_UPGRADE')

     Message: Table upgrade required. Please do "REPAIR TABLE `%s`" to
     fix it!

   * Error: `1460' SQLSTATE: `42000' (`ER_SP_NO_AGGREGATE')

     Message: AGGREGATE is not supported for stored functions

   * Error: `1461' SQLSTATE: `42000'
     (`ER_MAX_PREPARED_STMT_COUNT_REACHED')

     Message: Can't create more than max_prepared_stmt_count statements
     (current value: %lu)

   * Error: `1462' SQLSTATE: `HY000' (`ER_VIEW_RECURSIVE')

     Message: `%s`.`%s` contains view recursion

   * Error: `1463' SQLSTATE: `42000' (`ER_NON_GROUPING_FIELD_USED')

     Message: non-grouping field '%s' is used in %s clause

   * Error: `1464' SQLSTATE: `HY000' (`ER_TABLE_CANT_HANDLE_SPKEYS')

     Message: The used table type doesn't support SPATIAL indexes

   * Error: `1465' SQLSTATE: `HY000' (`ER_NO_TRIGGERS_ON_SYSTEM_SCHEMA')

     Message: Triggers can not be created on system tables

   * Error: `1466' SQLSTATE: `HY000' (`ER_REMOVED_SPACES')

     Message: Leading spaces are removed from name '%s'

   * Error: `1467' SQLSTATE: `HY000' (`ER_AUTOINC_READ_FAILED')

     Message: Failed to read auto-increment value from storage engine

   * Error: `1468' SQLSTATE: `HY000' (`ER_USERNAME')

     Message: user name

   * Error: `1469' SQLSTATE: `HY000' (`ER_HOSTNAME')

     Message: host name

   * Error: `1470' SQLSTATE: `HY000' (`ER_WRONG_STRING_LENGTH')

     Message: String '%s' is too long for %s (should be no longer than
     %d)

   * Error: `1471' SQLSTATE: `HY000' (`ER_NON_INSERTABLE_TABLE')

     Message: The target table %s of the %s is not insertable-into

   * Error: `1472' SQLSTATE: `HY000' (`ER_ADMIN_WRONG_MRG_TABLE')

     Message: Table '%s' is differently defined or of non-MyISAM type
     or doesn't exist

   * Error: `1473' SQLSTATE: `HY000'
     (`ER_TOO_HIGH_LEVEL_OF_NESTING_FOR_SELECT')

     Message: Too high level of nesting for select

   * Error: `1474' SQLSTATE: `HY000' (`ER_NAME_BECOMES_EMPTY')

     Message: Name '%s' has become "

   * Error: `1475' SQLSTATE: `HY000' (`ER_AMBIGUOUS_FIELD_TERM')

     Message: First character of the FIELDS TERMINATED string is
     ambiguous; please use non-optional and non-empty FIELDS ENCLOSED BY

   * Error: `1476' SQLSTATE: `HY000' (`ER_FOREIGN_SERVER_EXISTS')

     Message: The foreign server, %s, you are trying to create already
     exists.

   * Error: `1477' SQLSTATE: `HY000' (`ER_FOREIGN_SERVER_DOESNT_EXIST')

     Message: The foreign server name you are trying to reference does
     not exist. Data source error: %s

   * Error: `1478' SQLSTATE: `HY000' (`ER_ILLEGAL_HA_CREATE_OPTION')

     Message: Table storage engine '%s' does not support the create
     option '%s'

   * Error: `1479' SQLSTATE: `HY000'
     (`ER_PARTITION_REQUIRES_VALUES_ERROR')

     Message: Syntax error: %s PARTITIONING requires definition of
     VALUES %s for each partition

   * Error: `1480' SQLSTATE: `HY000' (`ER_PARTITION_WRONG_VALUES_ERROR')

     Message: Only %s PARTITIONING can use VALUES %s in partition
     definition

   * Error: `1481' SQLSTATE: `HY000' (`ER_PARTITION_MAXVALUE_ERROR')

     Message: MAXVALUE can only be used in last partition definition

   * Error: `1482' SQLSTATE: `HY000' (`ER_PARTITION_SUBPARTITION_ERROR')

     Message: Subpartitions can only be hash partitions and by key

   * Error: `1483' SQLSTATE: `HY000' (`ER_PARTITION_SUBPART_MIX_ERROR')

     Message: Must define subpartitions on all partitions if on one
     partition

   * Error: `1484' SQLSTATE: `HY000'
     (`ER_PARTITION_WRONG_NO_PART_ERROR')

     Message: Wrong number of partitions defined, mismatch with
     previous setting

   * Error: `1485' SQLSTATE: `HY000'
     (`ER_PARTITION_WRONG_NO_SUBPART_ERROR')

     Message: Wrong number of subpartitions defined, mismatch with
     previous setting

   * Error: `1486' SQLSTATE: `HY000'
     (`ER_CONST_EXPR_IN_PARTITION_FUNC_ERROR')

     Message: Constant/Random expression in (sub)partitioning function
     is not allowed

   * Error: `1487' SQLSTATE: `HY000'
     (`ER_NO_CONST_EXPR_IN_RANGE_OR_LIST_ERROR')

     Message: Expression in RANGE/LIST VALUES must be constant

   * Error: `1488' SQLSTATE: `HY000' (`ER_FIELD_NOT_FOUND_PART_ERROR')

     Message: Field in list of fields for partition function not found
     in table

   * Error: `1489' SQLSTATE: `HY000'
     (`ER_LIST_OF_FIELDS_ONLY_IN_HASH_ERROR')

     Message: List of fields is only allowed in KEY partitions

   * Error: `1490' SQLSTATE: `HY000'
     (`ER_INCONSISTENT_PARTITION_INFO_ERROR')

     Message: The partition info in the frm file is not consistent with
     what can be written into the frm file

   * Error: `1491' SQLSTATE: `HY000'
     (`ER_PARTITION_FUNC_NOT_ALLOWED_ERROR')

     Message: The %s function returns the wrong type

   * Error: `1492' SQLSTATE: `HY000'
     (`ER_PARTITIONS_MUST_BE_DEFINED_ERROR')

     Message: For %s partitions each partition must be defined

   * Error: `1493' SQLSTATE: `HY000' (`ER_RANGE_NOT_INCREASING_ERROR')

     Message: VALUES LESS THAN value must be strictly increasing for
     each partition

   * Error: `1494' SQLSTATE: `HY000'
     (`ER_INCONSISTENT_TYPE_OF_FUNCTIONS_ERROR')

     Message: VALUES value must be of same type as partition function

   * Error: `1495' SQLSTATE: `HY000'
     (`ER_MULTIPLE_DEF_CONST_IN_LIST_PART_ERROR')

     Message: Multiple definition of same constant in list partitioning

   * Error: `1496' SQLSTATE: `HY000' (`ER_PARTITION_ENTRY_ERROR')

     Message: Partitioning can not be used stand-alone in query

   * Error: `1497' SQLSTATE: `HY000' (`ER_MIX_HANDLER_ERROR')

     Message: The mix of handlers in the partitions is not allowed in
     this version of MySQL

   * Error: `1498' SQLSTATE: `HY000' (`ER_PARTITION_NOT_DEFINED_ERROR')

     Message: For the partitioned engine it is necessary to define all
     %s

   * Error: `1499' SQLSTATE: `HY000' (`ER_TOO_MANY_PARTITIONS_ERROR')

     Message: Too many partitions (including subpartitions) were defined

   * Error: `1500' SQLSTATE: `HY000' (`ER_SUBPARTITION_ERROR')

     Message: It is only possible to mix RANGE/LIST partitioning with
     HASH/KEY partitioning for subpartitioning

   * Error: `1501' SQLSTATE: `HY000' (`ER_CANT_CREATE_HANDLER_FILE')

     Message: Failed to create specific handler file

   * Error: `1502' SQLSTATE: `HY000'
     (`ER_BLOB_FIELD_IN_PART_FUNC_ERROR')

     Message: A BLOB field is not allowed in partition function

   * Error: `1503' SQLSTATE: `HY000'
     (`ER_UNIQUE_KEY_NEED_ALL_FIELDS_IN_PF')

     Message: A %s must include all columns in the table's partitioning
     function

   * Error: `1504' SQLSTATE: `HY000' (`ER_NO_PARTS_ERROR')

     Message: Number of %s = 0 is not an allowed value

   * Error: `1505' SQLSTATE: `HY000'
     (`ER_PARTITION_MGMT_ON_NONPARTITIONED')

     Message: Partition management on a not partitioned table is not
     possible

   * Error: `1506' SQLSTATE: `HY000' (`ER_FOREIGN_KEY_ON_PARTITIONED')

     Message: Foreign key condition is not yet supported in conjunction
     with partitioning

   * Error: `1507' SQLSTATE: `HY000' (`ER_DROP_PARTITION_NON_EXISTENT')

     Message: Error in list of partitions to %s

   * Error: `1508' SQLSTATE: `HY000' (`ER_DROP_LAST_PARTITION')

     Message: Cannot remove all partitions, use DROP TABLE instead

   * Error: `1509' SQLSTATE: `HY000'
     (`ER_COALESCE_ONLY_ON_HASH_PARTITION')

     Message: COALESCE PARTITION can only be used on HASH/KEY partitions

   * Error: `1510' SQLSTATE: `HY000' (`ER_REORG_HASH_ONLY_ON_SAME_NO')

     Message: REORGANISE PARTITION can only be used to reorganise
     partitions not to change their numbers

   * Error: `1511' SQLSTATE: `HY000' (`ER_REORG_NO_PARAM_ERROR')

     Message: REORGANISE PARTITION without parameters can only be used
     on auto-partitioned tables using HASH PARTITIONs

   * Error: `1512' SQLSTATE: `HY000' (`ER_ONLY_ON_RANGE_LIST_PARTITION')

     Message: %s PARTITION can only be used on RANGE/LIST partitions

   * Error: `1513' SQLSTATE: `HY000' (`ER_ADD_PARTITION_SUBPART_ERROR')

     Message: Trying to Add partition(s) with wrong number of
     subpartitions

   * Error: `1514' SQLSTATE: `HY000'
     (`ER_ADD_PARTITION_NO_NEW_PARTITION')

     Message: At least one partition must be added

   * Error: `1515' SQLSTATE: `HY000'
     (`ER_COALESCE_PARTITION_NO_PARTITION')

     Message: At least one partition must be coalesced

   * Error: `1516' SQLSTATE: `HY000' (`ER_REORG_PARTITION_NOT_EXIST')

     Message: More partitions to reorganise than there are partitions

   * Error: `1517' SQLSTATE: `HY000' (`ER_SAME_NAME_PARTITION')

     Message: Duplicate partition name %s

   * Error: `1518' SQLSTATE: `HY000' (`ER_NO_BINLOG_ERROR')

     Message: It is not allowed to shut off binlog on this command

   * Error: `1519' SQLSTATE: `HY000' (`ER_CONSECUTIVE_REORG_PARTITIONS')

     Message: When reorganising a set of partitions they must be in
     consecutive order

   * Error: `1520' SQLSTATE: `HY000' (`ER_REORG_OUTSIDE_RANGE')

     Message: Reorganize of range partitions cannot change total ranges
     except for last partition where it can extend the range

   * Error: `1521' SQLSTATE: `HY000' (`ER_PARTITION_FUNCTION_FAILURE')

     Message: Partition function not supported in this version for this
     handler

   * Error: `1522' SQLSTATE: `HY000' (`ER_PART_STATE_ERROR')

     Message: Partition state cannot be defined from CREATE/ALTER TABLE

   * Error: `1523' SQLSTATE: `HY000' (`ER_LIMITED_PART_RANGE')

     Message: The %s handler only supports 32 bit integers in VALUES

   * Error: `1524' SQLSTATE: `HY000' (`ER_PLUGIN_IS_NOT_LOADED')

     Message: Plugin '%s' is not loaded

   * Error: `1525' SQLSTATE: `HY000' (`ER_WRONG_VALUE')

     Message: Incorrect %s value: '%s'

   * Error: `1526' SQLSTATE: `HY000' (`ER_NO_PARTITION_FOR_GIVEN_VALUE')

     Message: Table has no partition for value %s

   * Error: `1527' SQLSTATE: `HY000' (`ER_FILEGROUP_OPTION_ONLY_ONCE')

     Message: It is not allowed to specify %s more than once

   * Error: `1528' SQLSTATE: `HY000' (`ER_CREATE_FILEGROUP_FAILED')

     Message: Failed to create %s

   * Error: `1529' SQLSTATE: `HY000' (`ER_DROP_FILEGROUP_FAILED')

     Message: Failed to drop %s

   * Error: `1530' SQLSTATE: `HY000' (`ER_TABLESPACE_AUTO_EXTEND_ERROR')

     Message: The handler doesn't support autoextend of tablespaces

   * Error: `1531' SQLSTATE: `HY000' (`ER_WRONG_SIZE_NUMBER')

     Message: A size parameter was incorrectly specified, either number
     or on the form 10M

   * Error: `1532' SQLSTATE: `HY000' (`ER_SIZE_OVERFLOW_ERROR')

     Message: The size number was correct but we don't allow the digit
     part to be more than 2 billion

   * Error: `1533' SQLSTATE: `HY000' (`ER_ALTER_FILEGROUP_FAILED')

     Message: Failed to alter: %s

   * Error: `1534' SQLSTATE: `HY000' (`ER_BINLOG_ROW_LOGGING_FAILED')

     Message: Writing one row to the row-based binary log failed

   * Error: `1535' SQLSTATE: `HY000' (`ER_BINLOG_ROW_WRONG_TABLE_DEF')

     Message: Table definition on master and slave does not match: %s

   * Error: `1536' SQLSTATE: `HY000' (`ER_BINLOG_ROW_RBR_TO_SBR')

     Message: Slave running with -log-slave-updates must use row-based
     binary logging to be able to replicate row-based binary log events

   * Error: `1537' SQLSTATE: `HY000' (`ER_EVENT_ALREADY_EXISTS')

     Message: Event '%s' already exists

   * Error: `1538' SQLSTATE: `HY000' (`ER_EVENT_STORE_FAILED')

     Message: Failed to store event %s. Error code %d from storage
     engine.

   * Error: `1539' SQLSTATE: `HY000' (`ER_EVENT_DOES_NOT_EXIST')

     Message: Unknown event '%s'

   * Error: `1540' SQLSTATE: `HY000' (`ER_EVENT_CANT_ALTER')

     Message: Failed to alter event '%s'

   * Error: `1541' SQLSTATE: `HY000' (`ER_EVENT_DROP_FAILED')

     Message: Failed to drop %s

   * Error: `1542' SQLSTATE: `HY000'
     (`ER_EVENT_INTERVAL_NOT_POSITIVE_OR_TOO_BIG')

     Message: INTERVAL is either not positive or too big

   * Error: `1543' SQLSTATE: `HY000' (`ER_EVENT_ENDS_BEFORE_STARTS')

     Message: ENDS is either invalid or before STARTS

   * Error: `1544' SQLSTATE: `HY000' (`ER_EVENT_EXEC_TIME_IN_THE_PAST')

     Message: Event execution time is in the past. Event has been
     disabled

   * Error: `1545' SQLSTATE: `HY000' (`ER_EVENT_OPEN_TABLE_FAILED')

     Message: Failed to open mysql.event

   * Error: `1546' SQLSTATE: `HY000'
     (`ER_EVENT_NEITHER_M_EXPR_NOR_M_AT')

     Message: No datetime expression provided

   * Error: `1547' SQLSTATE: `HY000'
     (`ER_COL_COUNT_DOESNT_MATCH_CORRUPTED')

     Message: Column count of mysql.%s is wrong. Expected %d, found %d.
     The table is probably corrupted

   * Error: `1548' SQLSTATE: `HY000' (`ER_CANNOT_LOAD_FROM_TABLE')

     Message: Cannot load from mysql.%s. The table is probably corrupted

   * Error: `1549' SQLSTATE: `HY000' (`ER_EVENT_CANNOT_DELETE')

     Message: Failed to delete the event from mysql.event

   * Error: `1550' SQLSTATE: `HY000' (`ER_EVENT_COMPILE_ERROR')

     Message: Error during compilation of event's body

   * Error: `1551' SQLSTATE: `HY000' (`ER_EVENT_SAME_NAME')

     Message: Same old and new event name

   * Error: `1552' SQLSTATE: `HY000' (`ER_EVENT_DATA_TOO_LONG')

     Message: Data for column '%s' too long

   * Error: `1553' SQLSTATE: `HY000' (`ER_DROP_INDEX_FK')

     Message: Cannot drop index '%s': needed in a foreign key constraint

   * Error: `1554' SQLSTATE: `HY000'
     (`ER_WARN_DEPRECATED_SYNTAX_WITH_VER')

     Message: The syntax '%s' is deprecated and will be removed in
     MySQL %s. Please use %s instead

   * Error: `1555' SQLSTATE: `HY000' (`ER_CANT_WRITE_LOCK_LOG_TABLE')

     Message: You can't write-lock a log table. Only read access is
     possible

   * Error: `1556' SQLSTATE: `HY000' (`ER_CANT_LOCK_LOG_TABLE')

     Message: You can't use locks with log tables.

   * Error: `1557' SQLSTATE: `23000' (`ER_FOREIGN_DUPLICATE_KEY')

     Message: Upholding foreign key constraints for table '%s', entry
     '%s', key %d would lead to a duplicate entry

   * Error: `1558' SQLSTATE: `HY000'
     (`ER_COL_COUNT_DOESNT_MATCH_PLEASE_UPDATE')

     Message: Column count of mysql.%s is wrong. Expected %d, found %d.
     Created with MySQL %d, now running %d. Please use mysql_upgrade to
     fix this error.

   * Error: `1559' SQLSTATE: `HY000'
     (`ER_TEMP_TABLE_PREVENTS_SWITCH_OUT_OF_RBR')

     Message: Cannot switch out of the row-based binary log format when
     the session has open temporary tables

   * Error: `1560' SQLSTATE: `HY000'
     (`ER_STORED_FUNCTION_PREVENTS_SWITCH_BINLOG_FORMAT')

     Message: Cannot change the binary logging format inside a stored
     function or trigger

   * Error: `1561' SQLSTATE: `HY000'
     (`ER_NDB_CANT_SWITCH_BINLOG_FORMAT')

     Message: The NDB cluster engine does not support changing the
     binlog format on the fly yet

   * Error: `1562' SQLSTATE: `HY000' (`ER_PARTITION_NO_TEMPORARY')

     Message: Cannot create temporary table with partitions

   * Error: `1563' SQLSTATE: `HY000' (`ER_PARTITION_CONST_DOMAIN_ERROR')

     Message: Partition constant is out of partition function domain

   * Error: `1564' SQLSTATE: `HY000'
     (`ER_PARTITION_FUNCTION_IS_NOT_ALLOWED')

     Message: This partition function is not allowed

   * Error: `1565' SQLSTATE: `HY000' (`ER_DDL_LOG_ERROR')

     Message: Error in DDL log

   * Error: `1566' SQLSTATE: `HY000' (`ER_NULL_IN_VALUES_LESS_THAN')

     Message: Not allowed to use NULL value in VALUES LESS THAN

   * Error: `1567' SQLSTATE: `HY000' (`ER_WRONG_PARTITION_NAME')

     Message: Incorrect partition name

   * Error: `1568' SQLSTATE: `25001' (`ER_CANT_CHANGE_TX_ISOLATION')

     Message: Transaction isolation level can't be changed while a
     transaction is in progress

   * Error: `1569' SQLSTATE: `HY000' (`ER_DUP_ENTRY_AUTOINCREMENT_CASE')

     Message: ALTER TABLE causes auto_increment resequencing, resulting
     in duplicate entry '%s' for key '%s'

   * Error: `1570' SQLSTATE: `HY000' (`ER_EVENT_MODIFY_QUEUE_ERROR')

     Message: Internal scheduler error %d

   * Error: `1571' SQLSTATE: `HY000' (`ER_EVENT_SET_VAR_ERROR')

     Message: Error during starting/stopping of the scheduler. Error
     code %u

   * Error: `1572' SQLSTATE: `HY000' (`ER_PARTITION_MERGE_ERROR')

     Message: Engine cannot be used in partitioned tables

   * Error: `1573' SQLSTATE: `HY000' (`ER_CANT_ACTIVATE_LOG')

     Message: Cannot activate '%s' log

   * Error: `1574' SQLSTATE: `HY000' (`ER_RBR_NOT_AVAILABLE')

     Message: The server was not built with row-based replication

   * Error: `1575' SQLSTATE: `HY000' (`ER_BASE64_DECODE_ERROR')

     Message: Decoding of base64 string failed

   * Error: `1576' SQLSTATE: `HY000' (`ER_EVENT_RECURSION_FORBIDDEN')

     Message: Recursion of EVENT DDL statements is forbidden when body
     is present

   * Error: `1577' SQLSTATE: `HY000' (`ER_EVENTS_DB_ERROR')

     Message: Cannot proceed because system tables used by Event
     Scheduler were found damaged at server start

   * Error: `1578' SQLSTATE: `HY000' (`ER_ONLY_INTEGERS_ALLOWED')

     Message: Only integers allowed as number here

   * Error: `1579' SQLSTATE: `HY000' (`ER_UNSUPORTED_LOG_ENGINE')

     Message: This storage engine cannot be used for log tables"

   * Error: `1580' SQLSTATE: `HY000' (`ER_BAD_LOG_STATEMENT')

     Message: You cannot '%s' a log table if logging is enabled

   * Error: `1581' SQLSTATE: `HY000' (`ER_CANT_RENAME_LOG_TABLE')

     Message: Cannot rename '%s'. When logging enabled, rename to/from
     log table must rename two tables: the log table to an archive
     table and another table back to '%s'

   * Error: `1582' SQLSTATE: `42000'
     (`ER_WRONG_PARAMCOUNT_TO_NATIVE_FCT')

     Message: Incorrect parameter count in the call to native function
     '%s'

   * Error: `1583' SQLSTATE: `42000'
     (`ER_WRONG_PARAMETERS_TO_NATIVE_FCT')

     Message: Incorrect parameters in the call to native function '%s'

   * Error: `1584' SQLSTATE: `42000'
     (`ER_WRONG_PARAMETERS_TO_STORED_FCT')

     Message: Incorrect parameters in the call to stored function '%s'

   * Error: `1585' SQLSTATE: `HY000' (`ER_NATIVE_FCT_NAME_COLLISION')

     Message: This function '%s' has the same name as a native function

   * Error: `1586' SQLSTATE: `23000' (`ER_DUP_ENTRY_WITH_KEY_NAME')

     Message: Duplicate entry '%s' for key '%s'

   * Error: `1587' SQLSTATE: `HY000' (`ER_BINLOG_PURGE_EMFILE')

     Message: Too many files opened, please execute the command again

   * Error: `1588' SQLSTATE: `HY000'
     (`ER_EVENT_CANNOT_CREATE_IN_THE_PAST')

     Message: Event execution time is in the past and ON COMPLETION NOT
     PRESERVE is set. The event was dropped immediately after creation.

   * Error: `1589' SQLSTATE: `HY000'
     (`ER_EVENT_CANNOT_ALTER_IN_THE_PAST')

     Message: Event execution time is in the past and ON COMPLETION NOT
     PRESERVE is set. The event was dropped immediately after creation.

   * Error: `1590' SQLSTATE: `HY000' (`ER_SLAVE_INCIDENT')

     Message: The incident %s occured on the master. Message: %s

   * Error: `1591' SQLSTATE: `HY000'
     (`ER_NO_PARTITION_FOR_GIVEN_VALUE_SILENT')

     Message: Table has no partition for some existing values

   * Error: `1592' SQLSTATE: `HY000' (`ER_BINLOG_UNSAFE_STATEMENT')

     Message: Statement is not safe to log in statement format.

   * Error: `1593' SQLSTATE: `HY000' (`ER_SLAVE_FATAL_ERROR')

     Message: Fatal error: %s

   * Error: `1594' SQLSTATE: `HY000' (`ER_SLAVE_RELAY_LOG_READ_FAILURE')

     Message: Relay log read failure: %s

   * Error: `1595' SQLSTATE: `HY000'
     (`ER_SLAVE_RELAY_LOG_WRITE_FAILURE')

     Message: Relay log write failure: %s

   * Error: `1596' SQLSTATE: `HY000' (`ER_SLAVE_CREATE_EVENT_FAILURE')

     Message: Failed to create %s

   * Error: `1597' SQLSTATE: `HY000' (`ER_SLAVE_MASTER_COM_FAILURE')

     Message: Master command %s failed: %s

   * Error: `1598' SQLSTATE: `HY000' (`ER_BINLOG_LOGGING_IMPOSSIBLE')

     Message: Binary logging not possible. Message: %s

   * Error: `1599' SQLSTATE: `HY000' (`ER_VIEW_NO_CREATION_CTX')

     Message: View `%s`.`%s` has no creation context

   * Error: `1600' SQLSTATE: `HY000' (`ER_VIEW_INVALID_CREATION_CTX')

     Message: Creation context of view `%s`.`%s' is invalid

   * Error: `1601' SQLSTATE: `HY000' (`ER_SR_INVALID_CREATION_CTX')

     Message: Creation context of stored routine `%s`.`%s` is invalid

   * Error: `1602' SQLSTATE: `HY000' (`ER_TRG_CORRUPTED_FILE')

     Message: Corrupted TRG file for table `%s`.`%s`

   * Error: `1603' SQLSTATE: `HY000' (`ER_TRG_NO_CREATION_CTX')

     Message: Triggers for table `%s`.`%s` have no creation context

   * Error: `1604' SQLSTATE: `HY000' (`ER_TRG_INVALID_CREATION_CTX')

     Message: Trigger creation context of table `%s`.`%s` is invalid

   * Error: `1605' SQLSTATE: `HY000' (`ER_EVENT_INVALID_CREATION_CTX')

     Message: Creation context of event `%s`.`%s` is invalid

   * Error: `1606' SQLSTATE: `HY000' (`ER_TRG_CANT_OPEN_TABLE')

     Message: Cannot open table for trigger `%s`.`%s`

   * Error: `1607' SQLSTATE: `HY000' (`ER_CANT_CREATE_SROUTINE')

     Message: Cannot create stored routine `%s`. Check warnings

   * Error: `1608' SQLSTATE: `HY000' (`ER_SLAVE_AMBIGOUS_EXEC_MODE')

     Message: Ambiguous slave modes combination. %s

   * Error: `1609' SQLSTATE: `HY000'
     (`ER_NO_FORMAT_DESCRIPTION_EVENT_BEFORE_BINLOG_STATEMENT')

     Message: The BINLOG statement of type `%s` was not preceded by a
     format description BINLOG statement.

   * Error: `1610' SQLSTATE: `HY000' (`ER_SLAVE_CORRUPT_EVENT')

     Message: Corrupted replication event was detected

   * Error: `1611' SQLSTATE: `HY000' (`ER_LOAD_DATA_INVALID_COLUMN')

     Message: Invalid column reference (%s) in LOAD DATA

   * Error: `1612' SQLSTATE: `HY000' (`ER_LOG_PURGE_NO_FILE')

     Message: Being purged log %s was not found

   * Error: `1613' SQLSTATE: `HY000' (`ER_NEED_REPREPARE')

     Message: Prepared statement needs to be re-prepared

   * Error: `1614' SQLSTATE: `HY000' (`ER_DELAYED_NOT_SUPPORTED')

     Message: DELAYED option not supported for table '%s'


File: manual.info,  Node: error-messages-client,  Prev: error-messages-server,  Up: error-handling

B.3 Client Error Codes and Messages
===================================

Client error information comes from the following source files:

   * The Error values and the symbols in parentheses correspond to
     definitions in the `include/errmsg.h' MySQL source file.

   * The Message values correspond to the error messages that are
     listed in the `libmysql/errmsg.c' file.  `%d' and `%s' represent
     numbers and strings, respectively, that are substituted into the
     messages when they are displayed.

Because updates are frequent, it is possible that those files will
contain additional error information not listed here.

   * Error: `2000' (`CR_UNKNOWN_ERROR')

     Message: Unknown MySQL error

   * Error: `2001' (`CR_SOCKET_CREATE_ERROR')

     Message: Can't create UNIX socket (%d)

   * Error: `2002' (`CR_CONNECTION_ERROR')

     Message: Can't connect to local MySQL server through socket '%s'
     (%d)

   * Error: `2003' (`CR_CONN_HOST_ERROR')

     Message: Can't connect to MySQL server on '%s' (%d)

   * Error: `2004' (`CR_IPSOCK_ERROR')

     Message: Can't create TCP/IP socket (%d)

   * Error: `2005' (`CR_UNKNOWN_HOST')

     Message: Unknown MySQL server host '%s' (%d)

   * Error: `2006' (`CR_SERVER_GONE_ERROR')

     Message: MySQL server has gone away

   * Error: `2007' (`CR_VERSION_ERROR')

     Message: Protocol mismatch; server version = %d, client version =
     %d

   * Error: `2008' (`CR_OUT_OF_MEMORY')

     Message: MySQL client ran out of memory

   * Error: `2009' (`CR_WRONG_HOST_INFO')

     Message: Wrong host info

   * Error: `2010' (`CR_LOCALHOST_CONNECTION')

     Message: Localhost via UNIX socket

   * Error: `2011' (`CR_TCP_CONNECTION')

     Message: %s via TCP/IP

   * Error: `2012' (`CR_SERVER_HANDSHAKE_ERR')

     Message: Error in server handshake

   * Error: `2013' (`CR_SERVER_LOST')

     Message: Lost connection to MySQL server during query

   * Error: `2014' (`CR_COMMANDS_OUT_OF_SYNC')

     Message: Commands out of sync; you can't run this command now

   * Error: `2015' (`CR_NAMEDPIPE_CONNECTION')

     Message: Named pipe: %s

   * Error: `2016' (`CR_NAMEDPIPEWAIT_ERROR')

     Message: Can't wait for named pipe to host: %s pipe: %s (%lu)

   * Error: `2017' (`CR_NAMEDPIPEOPEN_ERROR')

     Message: Can't open named pipe to host: %s pipe: %s (%lu)

   * Error: `2018' (`CR_NAMEDPIPESETSTATE_ERROR')

     Message: Can't set state of named pipe to host: %s pipe: %s (%lu)

   * Error: `2019' (`CR_CANT_READ_CHARSET')

     Message: Can't initialize character set %s (path: %s)

   * Error: `2020' (`CR_NET_PACKET_TOO_LARGE')

     Message: Got packet bigger than 'max_allowed_packet' bytes

   * Error: `2021' (`CR_EMBEDDED_CONNECTION')

     Message: Embedded server

   * Error: `2022' (`CR_PROBE_SLAVE_STATUS')

     Message: Error on SHOW SLAVE STATUS:

   * Error: `2023' (`CR_PROBE_SLAVE_HOSTS')

     Message: Error on SHOW SLAVE HOSTS:

   * Error: `2024' (`CR_PROBE_SLAVE_CONNECT')

     Message: Error connecting to slave:

   * Error: `2025' (`CR_PROBE_MASTER_CONNECT')

     Message: Error connecting to master:

   * Error: `2026' (`CR_SSL_CONNECTION_ERROR')

     Message: SSL connection error

   * Error: `2027' (`CR_MALFORMED_PACKET')

     Message: Malformed packet

   * Error: `2028' (`CR_WRONG_LICENSE')

     Message: This client library is licensed only for use with MySQL
     servers having '%s' license

   * Error: `2029' (`CR_NULL_POINTER')

     Message: Invalid use of null pointer

   * Error: `2030' (`CR_NO_PREPARE_STMT')

     Message: Statement not prepared

   * Error: `2031' (`CR_PARAMS_NOT_BOUND')

     Message: No data supplied for parameters in prepared statement

   * Error: `2032' (`CR_DATA_TRUNCATED')

     Message: Data truncated

   * Error: `2033' (`CR_NO_PARAMETERS_EXISTS')

     Message: No parameters exist in the statement

   * Error: `2034' (`CR_INVALID_PARAMETER_NO')

     Message: Invalid parameter number

   * Error: `2035' (`CR_INVALID_BUFFER_USE')

     Message: Can't send long data for non-string/non-binary data types
     (parameter: %d)

   * Error: `2036' (`CR_UNSUPPORTED_PARAM_TYPE')

     Message: Using unsupported buffer type: %d (parameter: %d)

   * Error: `2037' (`CR_SHARED_MEMORY_CONNECTION')

     Message: Shared memory: %s

   * Error: `2038' (`CR_SHARED_MEMORY_CONNECT_REQUEST_ERROR')

     Message: Can't open shared memory; client could not create request
     event (%lu)

   * Error: `2039' (`CR_SHARED_MEMORY_CONNECT_ANSWER_ERROR')

     Message: Can't open shared memory; no answer event received from
     server (%lu)

   * Error: `2040' (`CR_SHARED_MEMORY_CONNECT_FILE_MAP_ERROR')

     Message: Can't open shared memory; server could not allocate file
     mapping (%lu)

   * Error: `2041' (`CR_SHARED_MEMORY_CONNECT_MAP_ERROR')

     Message: Can't open shared memory; server could not get pointer to
     file mapping (%lu)

   * Error: `2042' (`CR_SHARED_MEMORY_FILE_MAP_ERROR')

     Message: Can't open shared memory; client could not allocate file
     mapping (%lu)

   * Error: `2043' (`CR_SHARED_MEMORY_MAP_ERROR')

     Message: Can't open shared memory; client could not get pointer to
     file mapping (%lu)

   * Error: `2044' (`CR_SHARED_MEMORY_EVENT_ERROR')

     Message: Can't open shared memory; client could not create %s
     event (%lu)

   * Error: `2045' (`CR_SHARED_MEMORY_CONNECT_ABANDONED_ERROR')

     Message: Can't open shared memory; no answer from server (%lu)

   * Error: `2046' (`CR_SHARED_MEMORY_CONNECT_SET_ERROR')

     Message: Can't open shared memory; cannot send request event to
     server (%lu)

   * Error: `2047' (`CR_CONN_UNKNOW_PROTOCOL')

     Message: Wrong or unknown protocol

   * Error: `2048' (`CR_INVALID_CONN_HANDLE')

     Message: Invalid connection handle

   * Error: `2049' (`CR_SECURE_AUTH')

     Message: Connection using old (pre-4.1.1) authentication protocol
     refused (client option 'secure_auth' enabled)

   * Error: `2050' (`CR_FETCH_CANCELED')

     Message: Row retrieval was canceled by mysql_stmt_close() call

   * Error: `2051' (`CR_NO_DATA')

     Message: Attempt to read column without prior row fetch

   * Error: `2052' (`CR_NO_STMT_METADATA')

     Message: Prepared statement contains no metadata

   * Error: `2053' (`CR_NO_RESULT_SET')

     Message: Attempt to read a row while there is no result set
     associated with the statement

   * Error: `2054' (`CR_NOT_IMPLEMENTED')

     Message: This feature is not implemented yet

   * Error: `2055' (`CR_SERVER_LOST_EXTENDED')

     Message: Lost connection to MySQL server at '%s', system error: %d

   * Error: `2056' (`CR_STMT_CLOSED')

     Message: Statement closed indirectly because of a preceeding %s()
     call

   * Error: `2057' (`CR_NEW_STMT_METADATA')

     Message: The number of columns in the result set differs from the
     number of bound buffers. You must reset the statement, rebind the
     result set columns, and execute the statement again


File: manual.info,  Node: news,  Next: restrictions,  Prev: error-handling,  Up: Top

Appendix C MySQL Change History
*******************************

* Menu:

* news-5-1-x::                   Changes in release 5.1.x (Development)
* myodbc-news::                  MySQL Connector/ODBC (MyODBC) Change History
* connector-net-news::           MySQL Connector/NET Change History
* vstudio-plugin-news::          MySQL Visual Studio Plugin Change History
* cj-news::                      MySQL Connector/J Change History
* news-connector-mxj::           MySQL Connector/MXJ Change History
* mysql-proxy-news::             MySQL Proxy Change History

This appendix lists the changes from version to version in the MySQL
source code through the latest version of MySQL 5.1, which is currently
MySQL 5.1.28. Starting with MySQL 5.0, we began offering a new version
of the Manual for each new series of MySQL releases (5.0, 5.1, and so
on). For information about changes in previous release series of the
MySQL database software, see the corresponding version of this Manual.
For information about legacy versions of the MySQL software through the
4.1 series, see `MySQL 3.23, 4.0, 4.1 Reference Manual'.

We update this section as we add new features in the 5.1 series, so
that everybody can follow the development process.

Note that we tend to update the manual at the same time we make changes
to MySQL. If you find a recent version of MySQL listed here that you
can't find on our download page (`http://dev.mysql.com/downloads/'), it
means that the version has not yet been released.

The date mentioned with a release version is the date of the last
Bazaar ChangeSet on which the release was based, not the date when the
packages were made available. The binaries are usually made available a
few days after the date of the tagged ChangeSet, because building and
testing all packages takes some time.

The manual included in the source and binary distributions may not be
fully accurate when it comes to the release changelog entries, because
the integration of the manual happens at build time. For the most
up-to-date release changelog, please refer to the online version
instead.


File: manual.info,  Node: news-5-1-x,  Next: myodbc-news,  Prev: news,  Up: news

C.1 Changes in release 5.1.x (Development)
==========================================

* Menu:

* news-5-1-28::                  Changes in MySQL 5.1.28 (Not yet released)
* news-5-1-27::                  Changes in MySQL 5.1.27 (Not released)
* news-5-1-26::                  Changes in MySQL 5.1.26 (30 June 2008)
* news-5-1-25::                  Changes in MySQL 5.1.25 (28 May 2008)
* news-5-1-24-maria::            Changes in MySQL 5.1.24-maria (Not yet released)
* news-5-1-24::                  Changes in MySQL 5.1.24 (08 April 2008)
* news-5-1-23::                  Changes in MySQL 5.1.23 (29 January 2008)
* news-5-1-22::                  Changes in MySQL 5.1.22 (24 September 2007: Release Candidate)
* news-5-1-21::                  Changes in MySQL 5.1.21 (16 August 2007)
* news-5-1-20::                  Changes in MySQL 5.1.20 (25 June 2007)
* news-5-1-19::                  Changes in MySQL 5.1.19 (25 May 2007)
* news-5-1-18::                  Changes in MySQL 5.1.18 (08 May 2007)
* news-5-1-17::                  Changes in MySQL 5.1.17 (04 April 2007)
* news-5-1-16::                  Changes in MySQL 5.1.16 (26 February 2007)
* news-5-1-15::                  Changes in MySQL 5.1.15 (25 January 2007)
* news-5-1-14::                  Changes in MySQL 5.1.14 (05 December 2006)
* news-5-1-13::                  Changes in MySQL 5.1.13 (Not released)
* news-5-1-12::                  Changes in MySQL 5.1.12 (24 October 2006)
* news-5-1-11::                  Changes in MySQL 5.1.11 (26 May 2006)
* news-5-1-10::                  Changes in MySQL 5.1.10 (Not released)
* news-5-1-9::                   Changes in MySQL 5.1.9 (12 April 2006)
* news-5-1-8::                   Changes in MySQL 5.1.8 (Not released)
* news-5-1-7::                   Changes in MySQL 5.1.7 (27 February 2006)
* news-5-1-6::                   Changes in MySQL 5.1.6 (01 February 2006)
* news-5-1-5::                   Changes in MySQL 5.1.5 (10 January 2006)
* news-5-1-4::                   Changes in MySQL 5.1.4 (21 December 2005)
* news-5-1-3::                   Changes in MySQL 5.1.3 (29 November 2005)
* news-5-1-2::                   Changes in MySQL 5.1.2 (Not released)
* news-5-1-1::                   Changes in MySQL 5.1.1 (Not released)

An overview of which features were added in MySQL 5.1 can be found
here: *Note mysql-nutshell::.

For a full list of changes, please refer to the changelog sections for
each individual 5.1.x release.

For changes relating to MySQL Cluster NDB 6.x, see *Note
mysql-cluster-news::.


File: manual.info,  Node: news-5-1-28,  Next: news-5-1-27,  Prev: news-5-1-x,  Up: news-5-1-x

C.1.1 Changes in MySQL 5.1.28 (Not yet released)
------------------------------------------------

Bugs fixed:

   * *Incompatible Change*: An additional correction to the original
     MySQL 5.1.23 fix was made to normalize directory names before
     adding them to the list of directories. This prevents `/etc/' and
     `/etc' from being considered different, for example.  (Bug#20748
     (http://bugs.mysql.com/20748)) See also Bug#38180
     (http://bugs.mysql.com/38180)

   * *Partitioning*: A `LIST' partitioned `MyISAM' table returned
     erroneous results when an index was present on a column in the
     `WHERE' clause and `NOT IN' was used on that column.

     Searches using the index were also much slower then if the index
     were not present.  (Bug#35931 (http://bugs.mysql.com/35931))

   * *Partitioning*: `SELECT COUNT(*)' was not correct for some
     partitioned tables using a storage engine that did not support
     `HA_STATS_RECORDS_IS_EXACT'. Tables using the `ARCHIVE' storage
     engine were known to be affected.

     This was because `ha_partition::records()' was not implemented,
     and so the default `handler::records()' was used in its place.
     However, this is not correct behavior if the storage engine does
     not support `HA_STATS_RECORDS_IS_EXACT'.

     The solution was to implement `ha_partition::records()' as a
     wrapper around the underlying partition records.

     As a result of this fix, the rows column in the output of `EXPLAIN
     PARTITIONS' now includes the total number of records in the
     partitioned table.  (Bug#35745 (http://bugs.mysql.com/35745))

   * *Replication*: Some kinds of internal errors (such as `Out of
     stack') cuased the server to crash.  (Bug#37150
     (http://bugs.mysql.com/37150))

   * *Replication*: Row-based replication did not correctly copy
     `TIMESTAMP' values from a big-endian storage engine to a
     little-endian storage engine.  (Bug#37076
     (http://bugs.mysql.com/37076))

   * The fix for Bug#20748 (http://bugs.mysql.com/20748) caused a
     problem such that on Unix, MySQL programs looked for options in
     `~/my.cnf' rather than the standard location of `~/.my.cnf'.
     (Bug#38180 (http://bugs.mysql.com/38180))

   * For `InnoDB' tables, `ORDER BY ...  DESC' sometimes returned
     results in ascending order.  (Bug#37830
     (http://bugs.mysql.com/37830))

   * The server returned unexpected results if a right side of the `NOT
     IN' clause consisted of the `NULL' value and some constants of the
     same type. For example, this query might return 3, 4, 5, and so
     forth if a table contained those values:

          SELECT * FROM t WHERE NOT t.id IN (NULL, 1, 2);

     (Bug#37761 (http://bugs.mysql.com/37761))

   * Setting the session value of the `innodb_table_locks' system
     variable caused a server crash.  (Bug#37669
     (http://bugs.mysql.com/37669))

   * Killing a query that used an `EXISTS' subquery as the argument to
     `SUM()' or `AVG()' caused a server crash.  (Bug#37627
     (http://bugs.mysql.com/37627))

   * `SELECT DISTINCT' from a simple view on an `InnoDB' table, where
     all selected columns belong to the same unique index key, returned
     incorrect results.  (Bug#36632 (http://bugs.mysql.com/36632))

   * The `mysql' client failed to recognize comment lines consisting of
     `--' followed by a newline.  (Bug#36244
     (http://bugs.mysql.com/36244))

   * The `UUID()' function returned UUIDs with the wrong time; this was
     because the offset for the time part in UUIDs was miscalculated.
     (Bug#35848 (http://bugs.mysql.com/35848))

   * Freeing of an internal parser stack during parsing of complex
     stored programs caused a server crash.  (Bug#35577
     (http://bugs.mysql.com/35577), Bug#37269
     (http://bugs.mysql.com/37269), Bug#37728
     (http://bugs.mysql.com/37728))

   * `mysqlbinlog' left temporary files on the disk after shutdown,
     leading to the pollution of the temporary directory, which
     eventually caused `mysqlbinlog' to fail. This caused problems in
     testing and other situations where `mysqlbinlog' might be invoked
     many times in a relatively short period of time.  (Bug#35543
     (http://bugs.mysql.com/35543))

   * Index scans performed with the `sort_union()' access method
     returned bad data when the `sort_buffer_size' limit was reached.
     (Bug#35478 (http://bugs.mysql.com/35478))

   * A significant slowdown occurred when many `SELECT' statements that
     return many rows from `InnoDB' tables were running concurrently.
     (Bug#34409 (http://bugs.mysql.com/34409))

   * Fast `ALTER TABLE' operations were not fast for columns that used
     multibyte character sets.  (Bug#33873
     (http://bugs.mysql.com/33873))

   * The internal functions `my_getsystime()', `my_micro_time()', and
     `my_micro_time_and_time()' did not work correctly on Windows. One
     symptom was that uniqueness of `UUID()' values could be
     compromised.  (Bug#33748 (http://bugs.mysql.com/33748))

   * Cached queries that used 256 or more tables were not properly
     cached, so that later query invalidation due to a `TRUNCATE TABLE'
     for one of the tables caused the server to hang.  (Bug#33362
     (http://bugs.mysql.com/33362))

   * In some cases, the parser interpreted the `;' character as the end
     of input and misinterpreted stored program definitions.
     (Bug#26030 (http://bugs.mysql.com/26030))

   * After executing a prepared statement that accesses a stored
     function, the next execution would fail to find the function if
     the stored function cache was flushed in the meantime.  (Bug#12093
     (http://bugs.mysql.com/12093), Bug#21294
     (http://bugs.mysql.com/21294))


File: manual.info,  Node: news-5-1-27,  Next: news-5-1-26,  Prev: news-5-1-28,  Up: news-5-1-x

C.1.2 Changes in MySQL 5.1.27 (Not released)
--------------------------------------------

Functionality added or changed:

   * `mysqltest' now installs signal handlers and generates a stack
     trace if it crashes.  (Bug#37003 (http://bugs.mysql.com/37003))

Bugs fixed:

   * The fix for Bug#33812 (http://bugs.mysql.com/33812) had the side
     effect of causing the `mysql' client not to be able to read some
     dump files produced with `mysqldump'. To address this, that fix
     was reverted.  (Bug#38158 (http://bugs.mysql.com/38158))


File: manual.info,  Node: news-5-1-26,  Next: news-5-1-25,  Prev: news-5-1-27,  Up: news-5-1-x

C.1.3 Changes in MySQL 5.1.26 (30 June 2008)
--------------------------------------------

Functionality added or changed:

   * *Important Change*: *Incompatible Change*: The `FEDERATED' storage
     engine is now disabled by default in binary distributions. The
     engine is still available and can be enabled by starting the
     server with the `--federated' option.  (Bug#37069
     (http://bugs.mysql.com/37069))

Bugs fixed:

   * *Replication*: Performing an insert on a table having an
     `AUTO_INCREMENT' column and an `INSERT' trigger that was being
     replicated from a master running MySQL 5.0 or any version of MySQL
     5.1 up to and including MySQL 5.1.11 to a slave running MySQL
     5.1.12 or later caused the replication slave to crash.  (Bug#36443
     (http://bugs.mysql.com/36443)) See also Bug#33029
     (http://bugs.mysql.com/33029)

   * Some binary distributions had a duplicate `-64bit' suffix in the
     filename.  (Bug#37623 (http://bugs.mysql.com/37623))

   * Row-based replication broke for `utf8' `CHAR' columns longer than
     85 characters.  (Bug#37426 (http://bugs.mysql.com/37426))

   * `NOT IN' subqueries that selected `MIN()' or `MAX()' values but
     produced an empty result could cause a server crash.  (Bug#37004
     (http://bugs.mysql.com/37004))

   * `ha_innodb.so' was incorrectly installed in the `lib/mysql'
     directory rather than in `lib/mysql/plugin'.  (Bug#36434
     (http://bugs.mysql.com/36434))

   * An empty bit-string literal (`b''') caused a server crash. Now the
     value is parsed as an empty bit value (which is treated as an
     empty string in string context or 0 in numeric context).
     (Bug#35658 (http://bugs.mysql.com/35658))

   * The code for detecting a byte order mark (BOM) caused `mysql' to
     crash for empty input.  (Bug#35480 (http://bugs.mysql.com/35480))

   * The `mysql' client incorrectly parsed statements containing the
     word `delimiter' in mid-statement.

     The fix for this bug had the side effect of causing the problem
     reported in Bug#38158 (http://bugs.mysql.com/38158), so it was
     reverted in MySQL 5.1.27.  (Bug#33812
     (http://bugs.mysql.com/33812))


File: manual.info,  Node: news-5-1-25,  Next: news-5-1-24-maria,  Prev: news-5-1-26,  Up: news-5-1-x

C.1.4 Changes in MySQL 5.1.25 (28 May 2008)
-------------------------------------------

Functionality added or changed:

   * *Incompatible Change*: A change has been made to the way that the
     server handles prepared statements. This affects prepared
     statements processed at the SQL level (using the `PREPARE'
     statement) and those processed using the binary client-server
     protocol (using the *Note `mysql_stmt_prepare()':
     mysql-stmt-prepare. C API function).

     Previously, changes to metadata of tables or views referred to in
     a prepared statement could cause a server crash when the statement
     was next executed, or perhaps an error at execute time with a
     crash occurring later. For example, this could happen after
     dropping a table and recreating it with a different definition.

     Now metadata changes to tables or views referred to by prepared
     statements are detected and cause automatic repreparation of the
     statement when it is next executed. Metadata changes occur for DDL
     statements such as those that create, drop, alter, rename, or
     truncate tables, or that analyze, optimize, or repair tables.
     Repreparation also occurs after referenced tables or views are
     flushed from the table definition cache, either implicitly to make
     room for new entries in the cache, or explicitly due to `FLUSH
     TABLES'.

     Repreparation is automatic, but to the extent that it occurs,
     performance of prepared statements is diminished.

     Table content changes (for example, with `INSERT' or `UPDATE') do
     not cause repreparation, nor do `SELECT' statements.

     An incompatibility with previous versions of MySQL is that a
     prepared statement may now return a different set of columns or
     different column types from one execution to the next. For
     example, if the prepared statement is `SELECT * FROM t1', altering
     `t1' to contain a different number of columns causes the next
     execution to return a number of columns different from the
     previous execution.

     Older versions of the client library cannot handle this change in
     behavior. For applications that use prepared statements with the
     new server, an upgrade to the new client library is strongly
     recommended.

     Along with this change to statement repreparation, the default
     value of the `table_definition_cache' system variable has been
     increased from 128 to 256. The purpose of this increase is to
     lessen the chance that prepared statements will need repreparation
     due to referred-to tables/views having been flushed from the cache
     to make room for new entries.

     A new status variable, `Com_stmt_reprepare', has been introduced
     to track the number of repreparations.  (Bug#27420
     (http://bugs.mysql.com/27420), Bug#27430
     (http://bugs.mysql.com/27430), Bug#27690
     (http://bugs.mysql.com/27690))

   * *Important Change*: Some changes were made to `CHECK TABLE ... FOR
     UPGRADE' and `REPAIR TABLE' with respect to detection and handling
     of tables with incompatible `.frm' files (files created with a
     different version of the MySQL server). These changes also affect
     `mysqlcheck' because that program uses `CHECK TABLE' and `REPAIR'
     table, and thus also `mysql_upgrade' because that program invokes
     `mysqlcheck'.

        * If your table was created by a different version of the MySQL
          server than the one you are currently running, `CHECK TABLE
          ... FOR UPGRADE' indicates that the table has an `.frm' file
          with an incompatible version. In this case, the result set
          returned by `CHECK TABLE' contains a line with a `Msg_type'
          value of `error' and a `Msg_text' value of `Table upgrade
          required. Please do "REPAIR TABLE `TBL_NAME`" to fix it!'

        * `REPAIR TABLE' without `USE_FRM' upgrades the `.frm' file to
          the current version.

        * If you use `REPAIR TABLE ...USE_FRM' and your table was
          created by a different version of the MySQL server than the
          one you are currently running, `REPAIR TABLE' will not
          attempt to repair the table. In this case, the result set
          returned by `REPAIR TABLE' contains a line with a `Msg_type'
          value of `error' and a `Msg_text' value of `Failed repairing
          incompatible .FRM file'.

          Previously, use of `REPAIR TABLE ...USE_FRM' with a table
          created by a different version of the MySQL server risked the
          loss of all rows in the table.

     (Bug#36055 (http://bugs.mysql.com/36055))

   * `mysql_upgrade' now has a `--tmpdir' option to enable the location
     of temporary files to be specified.  (Bug#36469
     (http://bugs.mysql.com/36469))

   * `mysqldump' now adds the `LOCAL' qualifier to the `FLUSH TABLES'
     statement that is sent to the server when the `--master-data'
     option is enabled. This prevents the `FLUSH TABLES' statement from
     replicating to slaves, which is disadvantageous because it would
     cause slaves to block while the statement executes.  (Bug#35157
     (http://bugs.mysql.com/35157)) See also Bug#38303
     (http://bugs.mysql.com/38303)

Bugs fixed:

   * *Important Change*: The server no longer issues warnings for
     truncation of excess spaces for values inserted into `CHAR'
     columns.  This reverts a change in the previous release that caused
     warnings to be issued.  (Bug#30059 (http://bugs.mysql.com/30059))

   * *Replication*: `CREATE PROCEDURE' and `CREATE FUNCTION' statements
     containing extended comments were not written to the binary log
     correctly, causing parse errors on the slave.  (Bug#36570
     (http://bugs.mysql.com/36570)) See also Bug#32575
     (http://bugs.mysql.com/32575)

   * *Replication*: When flushing tables, there was a slight chance
     that the flush occurred between the processing of one table map
     event and the next. Since the tables were opened one by one,
     subsequent locking of tables would cause the slave to crash. This
     problem was observed when replicating `NDBCLUSTER' or `InnoDB'
     tables, when executing multi-table updates, and when a trigger or
     a stored routine performed an (additional) insert on a table so
     that two tables were effectively being inserted into in the same
     statement.  (Bug#36197 (http://bugs.mysql.com/36197))

   * *Replication*: `CREATE VIEW' statements containing extended
     comments were not written to the binary log correctly, causing
     parse errors on the slave. Now, all comments are stripped from
     such statements before being written to the binary log.
     (Bug#32575 (http://bugs.mysql.com/32575)) See also Bug#36570
     (http://bugs.mysql.com/36570)

   * On Windows 64-bit systems, temporary variables of `long' types
     were used to store `ulong' values, causing key cache
     initialization to receive distorted parameters. The effect was
     that setting `key_buffer_size' to values of 2GB or more caused
     memory exhaustion to due allocation of too much memory.
     (Bug#36705 (http://bugs.mysql.com/36705))

   * Multiple-table `UPDATE' statements that used a temporary table
     could fail to update all qualifying rows or fail with a spurious
     duplicate-key error.  (Bug#36676 (http://bugs.mysql.com/36676))

   * A `REGEXP' match could return incorrect rows when the previous row
     matched the expression and used `CONCAT()' with an empty string.
     (Bug#36488 (http://bugs.mysql.com/36488))

   * `mysqltest' ignored the value of `--tmpdir' in one place.
     (Bug#36465 (http://bugs.mysql.com/36465))

   * When updating an existing instance (for example, from MySQL 5.0 to
     5.1, or 5.1 to 6.0), the Instance Configuration Wizard
     unnecessarily prompted for a `root' password when there was an
     existing `root' password.  (Bug#36305
     (http://bugs.mysql.com/36305))

   * Conversion of a `FLOAT ZEROFILL' value to string could cause a
     server crash if the value was `NULL'.  (Bug#36139
     (http://bugs.mysql.com/36139))

   * On Windows, the installer attempted to use JScript to determine
     whether the target data directory already existed. On Windows
     Vista x64, this resulted in an error because the installer was
     attempting to run the JScript in a 32-bit engine, which wasn't
     registered on Vista. The installer no longer uses JScript but
     instead relies on a native WiX command.  (Bug#36103
     (http://bugs.mysql.com/36103))

   * `mysqltest' was performing escape processing for the
     `--replace_result' command, which it should not have been.
     (Bug#36041 (http://bugs.mysql.com/36041))

   * An error in calculation of the precision of zero-length items
     (such as `NULL') caused a server crash for queries that employed
     temporary tables.  (Bug#36023 (http://bugs.mysql.com/36023))

   * For `EXPLAIN EXTENDED', execution of an uncorrelated `IN' subquery
     caused a crash if the subquery required a temporary table for its
     execution.  (Bug#36011 (http://bugs.mysql.com/36011))

   * The `MERGE' storage engine did a table scan for `SELECT COUNT(*)'
     statements when it could calculate the number of records from the
     underlying tables.  (Bug#36006 (http://bugs.mysql.com/36006))

   * The server crashed inside `NOT IN' subqueries with an impossible
     `WHERE' or `HAVING' clause, such as `NOT IN (SELECT ... FROM t1,
     t2, ... WHERE 0)'.  (Bug#36005 (http://bugs.mysql.com/36005))

   * The Event Scheduler was not designed to work under the embedded
     server. It is now disabled for the embedded server, and the
     `event_scheduler' system variable is not displayed.  (Bug#35997
     (http://bugs.mysql.com/35997))

   * Grouping or ordering of long values in unindexed `BLOB' or `TEXT'
     columns with the `gbk' or `big5' character set crashed the server.
     (Bug#35993 (http://bugs.mysql.com/35993))

   * `SET GLOBAL debug=''' resulted in a Valgrind warning in
     `DbugParse()', which was reading beyond the end of the control
     string.  (Bug#35986 (http://bugs.mysql.com/35986))

   * The `prefer full scan on clustered primary key over full scan of
     any secondary key' optimizer rule introduced by Bug#26447
     (http://bugs.mysql.com/26447) caused a performance regression for
     some queries, so it has been disabled.  (Bug#35850
     (http://bugs.mysql.com/35850))

   * The server ignored any covering index used for `ref' access of a
     table in a query with `ORDER BY' if this index was incompatible
     with the `ORDER BY' list and there was another covering index
     compatible with this list. As a result, suboptimal execution plans
     were chosen for some queries that used an `ORDER BY' clause.
     (Bug#35844 (http://bugs.mysql.com/35844))

   * `mysql_upgrade' did not properly update the `mysql.event' table.
     (Bug#35824 (http://bugs.mysql.com/35824))

   * An incorrect error and message was produced for attempts to create
     a `MyISAM' table with an index (`.MYI') filename that was already
     in use by some other `MyISAM' table that was open at the same
     time. For example, this might happen if you use the same value of
     the `INDEX DIRECTORY' table option for tables belonging to
     different databases.  (Bug#35733 (http://bugs.mysql.com/35733))

   * Enabling the `read_only' system variable while autocommit mode was
     enabled caused `SELECT' statements for transactional storage
     engines to fail.  (Bug#35732 (http://bugs.mysql.com/35732))

   * The combination of `GROUP_CONCAT()', `DISTINCT', and `LEFT JOIN'
     could crash the server when the right table is empty.  (Bug#35298
     (http://bugs.mysql.com/35298))

   * Some binaries produced stack corruption messages due to being
     built with versions of `bison' older than 2.1.  Builds are now
     created using `bison' 2.3.  (Bug#34926
     (http://bugs.mysql.com/34926))

   * On Windows 64-bit builds, an apparent compiler bug caused memory
     overruns for code in `innobase/mem/*'.  Removed optimizations so
     as not to trigger this problem.  (Bug#34297
     (http://bugs.mysql.com/34297))

   * Several additional configuration scripts in the `BUILD' directory
     now are included in source distributions. These may be useful for
     users who wish to build MySQL from source. (See *Note
     installing-source-tree::, for information about what they do.)
     (Bug#34291 (http://bugs.mysql.com/34291))

   * Executing a `FLUSH PRIVILEGES' statement after creating a
     temporary table in the `mysql' database with the same name as one
     of the MySQL system tables caused the server to crash.

     *Note*:

     While it is possible to shadow a system table in this way, the
     temporary table exists only for the current user and connection,
     and does not effect any user privileges.

     (Bug#33275 (http://bugs.mysql.com/33275))

   * Assignment of relative pathnames to `general_log_file' or
     `slow_query_log_file' did not always work.  (Bug#32748
     (http://bugs.mysql.com/32748))

   * The `mysql.servers' table was not created during installation on
     Windows.  (Bug#28680 (http://bugs.mysql.com/28680), Bug#32797
     (http://bugs.mysql.com/32797))

   * The `jp' test suite was not working.  (Bug#28563
     (http://bugs.mysql.com/28563))

   * The internal `init_time()' library function was renamed to
     `my_init_time()' to avoid conflicts with external libraries.
     (Bug#26294 (http://bugs.mysql.com/26294))

   * The parser used signed rather than unsigned values in some cases
     that caused legal lengths in column declarations to be rejected.
     (Bug#15776 (http://bugs.mysql.com/15776))


File: manual.info,  Node: news-5-1-24-maria,  Next: news-5-1-24,  Prev: news-5-1-25,  Up: news-5-1-x

C.1.5 Changes in MySQL 5.1.24-maria (Not yet released)
------------------------------------------------------

The following changes apply only to builds of MySQL 5.1.24 that include
the `MARIA' storage engine.

Bugs fixed:

   * When creating tables not using the `MARIA' engine, it would be
     possible to create a table using the `TRANSACTIONAL' option, even
     though this option is not supported by non-`MARIA' tables. A
     warning will now be produced when using these options, but the
     option will still be recorded within the options for the table to
     allow for correct modification during `ALTER TABLE' operations.
     (Bug#34395 (http://bugs.mysql.com/34395))


File: manual.info,  Node: news-5-1-24,  Next: news-5-1-23,  Prev: news-5-1-24-maria,  Up: news-5-1-x

C.1.6 Changes in MySQL 5.1.24 (08 April 2008)
---------------------------------------------

Functionality added or changed:

   * *Important Change*: *MySQL Cluster*: *Packaging*: Beginning with
     this release, standard MySQL 5.1 binaries are no longer built with
     support for the `NDBCLUSTER' storage engine, and the `NDBCLUSTER'
     code included in 5.1 mainline sources is no longer guaranteed to be
     maintained or supported. Those using MySQL Cluster in MySQL 5.1.23
     and earlier MySQL 5.1 mainline releases should upgrade to MySQL
     Cluster NDB 6.2.15 or a later MySQL Cluster NDB 6.2 or 6.3 release.
     (Bug#36193 (http://bugs.mysql.com/36193))

   * *Important Change*: The `FEDERATED' storage engine is not included
     in binary distributions of MySQL 5.1.24. (It will be included
     again in 5.1.25.)

   * *Replication*: Introduced the `slave_exec_mode' system variable to
     control whether idempotent or strict mode is used for replication
     conflict resolution. Idempotent mode suppresses duplicate-key,
     no-key-found, and some other errors, and is needed for circular
     replication, multi-master replication, and some other complex
     replication setups when using MySQL Cluster.  Strict mode is the
     default.  (Bug#31609 (http://bugs.mysql.com/31609))

   * *Replication*: When running the server with
     `--binlog-format=MIXED' or `--binlog-format=STATEMENT', a query
     that referred to a system variable used the slave's value when
     replayed on the slave. This meant that, if the value of a system
     variable was inserted into a table, the slave differed from the
     master. Now, statements that refer to a system variable are marked
     as `unsafe', which means that:

        * When the server is using `--binlog-format=MIXED', the
          row-based format is used automatically to replicate these
          statements.

        * When the server is using `--binlog-format=STATEMENT', these
          statements produce a warning.

     (Bug#31168 (http://bugs.mysql.com/31168)) See also Bug#34732
     (http://bugs.mysql.com/34732)

   * The `PROCESS' privilege now is required to start or stop the
     `InnoDB' monitor tables (see linkend="innodb-monitor"/>).
     Previously, no privilege was required.  (Bug#34053
     (http://bugs.mysql.com/34053))

   * For binary `.tar.gz' packages, `mysqld' and other binaries now are
     compiled with debugging symbols included to enable easier use with
     a debugger. If you do not need debugging symbols and are short on
     disk space, you can use `strip' to remove the symbols from the
     binaries.  (Bug#33252 (http://bugs.mysql.com/33252))

   * Formerly, when the MySQL server crashed, the generated stack dump
     was numeric and required external tools to properly resolve the
     names of functions. This is not very helpful to users having a
     limited knowledge of debugging techniques. In addition, the
     generated stack trace contained only the names of functions and
     was formatted differently for each platform due to different stack
     layouts.

     Now it is possible to take advantage of newer versions of the GNU
     C Library provide a set of functions to obtain and manipulate
     stack traces from within the program. On systems that use the ELF
     binary format, the stack trace contains important information such
     as the shared object where the call was generated, an offset into
     the function, and the actual return address. Having the function
     name also makes possible the name demangling of C++ functions.

     The library generates meaningful stack traces on the following
     platforms: i386, x86_64, PowerPC, IA64, Alpha, and S390. On other
     platforms, a numeric stack trace is still produced, and the use of
     the `resolve_stack_dump' utility is still required.  (Bug#31891
     (http://bugs.mysql.com/31891))

   * `mysqltest' now has `mkdir' and `rmdir' commands for creating and
     removing directories.  (Bug#31004 (http://bugs.mysql.com/31004))

   * The server uses less memory when loading privileges containing
     table grants. (Patch provided by Google.)  (Bug#25175
     (http://bugs.mysql.com/25175))

   * Added the `Uptime_since_flush_status' status variable, which
     indicates the number of seconds since the most recent `FLUSH
     STATUS' statement. (From Jeremy Cole) (Bug#24822
     (http://bugs.mysql.com/24822))

   * `SHOW OPEN TABLES' now supports `FROM' and `LIKE' clauses.
     (Bug#12183 (http://bugs.mysql.com/12183))

   * The new read-only global system variables `report_host',
     `report_password', `report_port', and `report_user' system
     variables provide runtime access to the values of the corresponding
     `--report-host', `--report-password', `--report-port', and
     `--report-user' options.

   * Formerly it was possible to specify an `innodb_flush_method' value
     of `fdatasync' to obtain the default flush behavior of using
     `fdatasync()' for flushing.  This is no longer possible because it
     can be confusing that a value of `fdatasync' causes use of
     `fsync()' rather than `fdatasync()'.

   * The use of `InnoDB' hash indexes now can be controlled by setting
     the new `innodb_adaptive_hash_index' system variable at server
     startup. By default, this variable is enabled. See *Note
     innodb-adaptive-hash::.

Bugs fixed:

   * *Important Change*: *Security Fix*: It was possible to circumvent
     privileges through the creation of `MyISAM' tables employing the
     `DATA DIRECTORY' and `INDEX DIRECTORY' options to overwrite
     existing table files in the MySQL data directory. Use of the MySQL
     data directory in `DATA DIRECTORY' and `INDEX DIRECTORY' is now
     disallowed. This is now also true of these options when used with
     partitioned tables and individual partitions of such tables.
     (Bug#32167 (http://bugs.mysql.com/32167), CVE-2008-2079
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-2079))

   * *Security Fix*: A client that connects to a malicious server could
     be tricked by the server into sending files from the client host
     to the server. This occurs because the `libmysqlclient' client
     library would respond to a `FETCH LOCAL FILE' request from the
     server even if the request is sent for statements from the client
     other than `LOAD DATA LOCAL INFILE'. The client library has been
     modified to respond to a `FETCH LOCAL FILE' request from the
     server only if is is sent in response to a `LOAD DATA LOCAL INFILE'
     statement from the client.

     The client library now also checks whether `CLIENT_LOCAL_FILE' is
     set and refuses to send a local file if not.

     *Note*:

     Binary distributions ship with the `local-infile' capability
     enabled.  Applications that do not use this functionality should
     disable it to be safe.

     (Bug#29605 (http://bugs.mysql.com/29605))

   * *Important Change*: *Security Enhancement*: On Windows Vista and
     Windows Server 2008, a user without administrative privileges does
     not have write permissions to the `Program Files' directory where
     MySQL and the associated data files are normally installed. Using
     data files located in the standard `Program Files' installation
     directory could therefore cause MySQL to fail, or lead to
     potential security issues in an installed instance.

     To address the problem, on Windows XP, Windows Vista and Windows
     Server 2008, the datafiles and data file configuration are now set
     to the Microsoft recommended `AppData' folder. The `AppData'
     folder is typically located within the user's home directory.

     *Important*:

     When upgrading an existing 5.1.23 or 6.0.4 installation of MySQL
     you must take a backup of your data and configuration file
     (`my.ini' before installing the new version. To migrate your data,
     either extract the data and re-import (using `mysqldump', then
     upgrade and re-import using `mysql'), or back up your data,
     upgrade to the new version, and copy your existing data files from
     your old `datadir' directory to the new directory located within
     `AppData'.

     Failure to back up your data and follow these procedures may lead
     to data loss.

     (Bug#34593 (http://bugs.mysql.com/34593))

   * *Partitioning*: *Incompatible Change*: The following statements
     did not function correctly with corrupted or crashed tables and
     have been removed:

        * `ALTER TABLE ... ANALYZE PARTITION'

        * `ALTER TABLE ... CHECK PARTITION'

        * `ALTER TABLE ... OPTIMIZE PARTITION'

        * `ALTER TABLE ... REPAIR PARTITION'

     `ALTER TABLE ... REBUILD PARTITION' is unaffected by this change
     and continues to be available. This statement and `ALTER TABLE ...
     REORGANIZE PARTITION' may be used to analyze and optimize
     partitioned tables, since these operations cause the partition
     files to be rebuilt.  (Bug#20129 (http://bugs.mysql.com/20129))

   * *Incompatible Change*: In MySQL 5.1.23, the `last_errno' and
     `last_error' members of the `NET' structure in `mysql_com.h' were
     renamed to `client_last_errno' and `client_last_error'. This was
     found to cause problems for connectors that use the internal `NET'
     structure for error handling. The change has been reverted.
     (Bug#34655 (http://bugs.mysql.com/34655)) See also Bug#12713
     (http://bugs.mysql.com/12713)

   * *Incompatible Change*: For packages that are built within their
     own prefix (for example, `/usr/local/mysql') the plugin directory
     will be `lib/plugin'. For packages that are built to be installed
     into a system-wide prefix (such as RPM packages with a prefix of
     `/usr'), the plugin directory will be `lib/mysql/plugin' to ensure
     a clean `/usr/lib' hierarchy. In both cases, the `$pkglibdir'
     configuration setting is used at build time to set the plugin
     directory.

     The current plugin directory location is available as the value of
     the `plugin_dir' system variable as before, but the `mysql_config'
     script now has a `--plugindir' option that can be used externally
     to the server by third-party plugin writers to obtain the default
     plugin directory pathname and configure their installation
     directory appropriately.  (Bug#31736 (http://bugs.mysql.com/31736))

   * *Incompatible Change*: The `utf8_general_ci' and `ucs2_general_ci'
     collations did not sort the letter "U+00DF SHARP S" equal to `'s''.

     As a result of this fix, any indexes on columns that use these
     collations (but only columns that use SHARP S) must be rebuilt
     when upgrading to 5.1.24 or higher. To do this, use `ALTER TABLE'
     to drop and re-add the indexes, or `mysqldump' to dump the
     affected tables and `mysql' to reload the dump file.  (Bug#27877
     (http://bugs.mysql.com/27877)) See also Bug#37046
     (http://bugs.mysql.com/37046)

   * *Important Change*: *Replication*: When the master crashed during
     an update on a transactional table while in `AUTOCOMMIT' mode, the
     slave failed. This fix causes every transaction (including
     `AUTOCOMMIT' transactions) to be recorded in the binlog as
     starting with a `BEGIN' and ending with a `COMMIT' or `ROLLBACK'.
     (Bug#26395 (http://bugs.mysql.com/26395))

   * *Important Change*: It was possible to use `FRAC_SECOND' as a
     synonym for `MICROSECOND' with `DATE_ADD()', `DATE_SUB()', and
     `INTERVAL'; now, using `FRAC_SECOND' with anything other than
     `TIMESTAMPADD()' or `TIMESTAMPDIFF()' produces a syntax error.

     It is now possible (and preferable) to use `MICROSECOND' with
     `TIMESTAMPADD()' and `TIMESTAMPDIFF()', and `FRAC_SECOND' is now
     deprecated.  (Bug#33834 (http://bugs.mysql.com/33834))

   * *Important Change*: `InnoDB' free space information is now shown in
     the `Data_free' column of `SHOW TABLE STATUS' and in the
     `DATA_FREE' column of the `INFORMATION_SCHEMA.TABLES' table.
     (Bug#32440 (http://bugs.mysql.com/32440)) This regression was
     introduced by Bug#11379 (http://bugs.mysql.com/11379)

   * *Important Change*: The server handled truncation of values having
     excess trailing spaces into `CHAR', `VARCHAR', and `TEXT' columns
     in different ways. This behavior has now been made consistent for
     columns of all three of these types, and now follows the existing
     behavior of `VARCHAR' columns in this regard; that is, a `Note' is
     always issued whenever such truncation occurs.

     This change does not affect columns of these three types when
     using a binary encoding; `BLOB' columns are also unaffected by the
     change, since they always use a binary encoding.  (Bug#30059
     (http://bugs.mysql.com/30059))

   * *Important Change*: An `AFTER UPDATE' trigger was not invoked when
     the `UPDATE' did not make any changes to the table for which the
     trigger was defined. Now `AFTER UPDATE' triggers behave the same
     in this regard as do `BEFORE UPDATE' triggers, which are invoked
     whether the `UPDATE' makes any changes in the table or not.
     (Bug#23771 (http://bugs.mysql.com/23771))

   * *Replication*: *Important Note*: Network timeouts between the
     master and the slave could result in corruption of the relay log.
     This fix rectifies a long-standing replication issue when using
     unreliable networks, including replication over wide area networks
     such as the Internet. If you experience reliability issues and see
     many `You have an error in your SQL syntax' errors on replication
     slaves, we strongly recommend that you upgrade to a MySQL version
     which includes this fix.  (Bug#26489 (http://bugs.mysql.com/26489))

   * *Partitioning*: In some cases, matching rows from a partitioned
     `MyISAM' using a `BIT' column as the primary key were not found by
     queries.  (Bug#34358 (http://bugs.mysql.com/34358))

   * *Partitioning*: Enabling `innodb_file_per_table' produced problems
     with partitioning and tablespace operations on partitioned
     `InnoDB' tables, in some cases leading to corrupt partitions or
     causing the server to crash.  (Bug#33429
     (http://bugs.mysql.com/33429))

   * *Partitioning*: A table defined using `PARTITION BY KEY' and
     having a `BIT' column referenced in the partitioning key did not
     behave correctly; some rows could be inserted into the wrong
     partition, causing wrong results to be returned from queries.
     (Bug#33379 (http://bugs.mysql.com/33379))

   * *Partitioning*: When `ALTER TABLE DROP PARTITION' was executed on
     a table on which there was a trigger, the statement failed with an
     error. This occurred even if the trigger did not reference any
     tables.  (Bug#32943 (http://bugs.mysql.com/32943))

   * *Partitioning*: Currently, all partitions of a partitioned table
     must use the same storage engine. One may optinally specify the
     storage engine on a per-partition basis; however, where this is the
     done, the storage engine must be the same as used by the table as
     a whole. `ALTER TABLE' did not enforce these rules correctly, the
     result being that incaccurate error messages were shown when
     trying to use the statement to change the storage engine used by
     an individual partition or partitions.  (Bug#31931
     (http://bugs.mysql.com/31931))

   * *Partitioning*: Using the DATA DIRECTORY and INDEX DIRECTORY
     options for partitions with CREATE TABLE or ALTER TABLE statements
     appeared to work on Windows, although they are not supported by
     MySQL on Windows systems, and subsequent attempts to use the tables
     referenced caused errors. Now these options are disabled on
     Windows, and attempting to use them generates a warning.
     (Bug#30459 (http://bugs.mysql.com/30459))

   * *Replication*: The failure of a `CREATE TABLE ... ENGINE=InnoDB ...
     SELECT' statement caused the slave to lose data.  (Bug#35762
     (http://bugs.mysql.com/35762))

   * *Replication*: `INSERT_ID' was not written to the binary log for
     inserts into `BLACKHOLE' tables.  (Bug#35178
     (http://bugs.mysql.com/35178))

   * *Replication*: When using statement-based replication and a
     `DELETE', `UPDATE', or `INSERT ... SELECT' statement using a
     `LIMIT' clause is encountered, a warning that the statement is not
     safe to replicate in statement mode is now issued; when using
     `MIXED' mode, the statement is now replicated using the row-based
     format.  (Bug#34768 (http://bugs.mysql.com/34768))

   * *Replication*: `mysqlbinlog' did not output the values of
     `auto_increment_increment' and `auto_increment_offset' when both
     were equal to their default values (for both of these variables,
     the default is 1). This meant that a binary log recorded by a
     client using the defaults for both variables and then replayed on
     another client using its own values for either or both of these
     variables produced erroneous results.  (Bug#34732
     (http://bugs.mysql.com/34732)) See also Bug#31168
     (http://bugs.mysql.com/31168)

   * *Replication*: When the Windows version of `mysqlbinlog' read 4.1
     binlogs containing `LOAD DATA INFILE' statements, it output
     backslashes as path separators, causing problems for client
     programs expecting forward slashes. In such cases, it now converts
     `\\' to `/' in directory paths.  (Bug#34355
     (http://bugs.mysql.com/34355))

   * *Replication*: `SHOW SLAVE STATUS' failed when slave I/O was about
     to terminate.  (Bug#34305 (http://bugs.mysql.com/34305))

   * *Replication*: The character sets and collations used for constant
     identifiers in stored procedures were not replicated correctly.
     (Bug#34289 (http://bugs.mysql.com/34289))

   * *Replication*: `mysqlbinlog' from a 5.1 or later MySQL
     distribution could not read binary logs generated by a 4.1 server
     when the logs contained `LOAD DATA INFILE' statements.  (Bug#34141
     (http://bugs.mysql.com/34141)) This regression was introduced by
     Bug#32407 (http://bugs.mysql.com/32407)

   * *Replication*: A `CREATE USER', `DROP USER', or `RENAME USER'
     statement that fails on the master, or that is a duplicate of any
     of these statements, is no longer written to the binlog;
     previously, either of these occurrences could cause the slave to
     fail.

     (Bug#33862 (http://bugs.mysql.com/33862)) See also Bug#29749
     (http://bugs.mysql.com/29749)

   * *Replication*: `SHOW BINLOG EVENTS' could fail when the binlog
     contained one or more events whose size was close to the value of
     `max_allowed_packet'.  (Bug#33413 (http://bugs.mysql.com/33413))

   * *Replication*: An extraneous `ROLLBACK' statement was written to
     the binary log by a connection that did not use any transactional
     tables.  (Bug#33329 (http://bugs.mysql.com/33329))

   * *Replication*: `mysqlbinlog' failed to release all of its memory
     after terminating abnormally.  (Bug#33247
     (http://bugs.mysql.com/33247))

   * *Replication*: When a stored routine or trigger, running on a
     master that used MySQL 5.0 or MySQL 5.1.11 or earlier, performed
     an insert on an `AUTO_INCREMENT' column, the `INSERT_ID' value was
     not replicated correctly to a slave running MySQL 5.1.12 or later
     (including any MySQL 6.0 release).  (Bug#33029
     (http://bugs.mysql.com/33029)) See also Bug#19630
     (http://bugs.mysql.com/19630)

   * *Replication*: The error message generated due to lack of a
     default value for an extra column was not sufficiently informative.
     (Bug#32971 (http://bugs.mysql.com/32971))

   * *Replication*: When a user variable was used inside an `INSERT'
     statement, the corresponding binlog event was not written to the
     binlog correctly.  (Bug#32580 (http://bugs.mysql.com/32580))

   * *Replication*: When using row-based replication, deletes from a
     table with a foreign key constraint failed on the slave.
     (Bug#32468 (http://bugs.mysql.com/32468))

   * *Replication*: The `--base64-output' option for `mysqlbinlog' was
     not honored for all types of events. This interfered in some cases
     with performing point-in-time recovery.  (Bug#32407
     (http://bugs.mysql.com/32407))

   * *Replication*: SQL statements containing comments using `--'
     syntax were not replayable by `mysqlbinlog', even though such
     statements replicated correctly.  (Bug#32205
     (http://bugs.mysql.com/32205))

   * *Replication*: When using row-based replication from a master
     running MySQL 5.1.21 or earlier to a slave running 5.1.22 or
     later, updates of integer columns failed on the slave with `Error
     in Unknown event: row application failed'.  (Bug#31583
     (http://bugs.mysql.com/31583)) This regression was introduced by
     Bug#21842 (http://bugs.mysql.com/21842)

   * *Replication*: Replicating write, update, or delete events from a
     master running MySQL 5.1.15 or earlier to a slave running 5.1.16 or
     later caused the slave to crash.  (Bug#31581
     (http://bugs.mysql.com/31581))

   * *Replication*: When using row-based replication, the slave stopped
     when attempting to delete non-existent rows from a slave table
     without a primary key. In addition, no error was reported when
     this occurred.  (Bug#31552 (http://bugs.mysql.com/31552))

   * *Replication*: Errors due to server ID conflicts were reported
     only in the slave's error log; now these errors are also shown in
     the `Server_IO_State' column in the output of `SHOW SLAVE STATUS'.
     (Bug#31316 (http://bugs.mysql.com/31316))

   * *Replication*: `STOP SLAVE' did not stop connection attempts
     properly. If the IO slave thread was attempting to connect, `STOP
     SLAVE' waited for the attempt to finish, sometimes for a long
     period of time, rather than stopping the slave immediately.
     (Bug#31024 (http://bugs.mysql.com/31024)) See also Bug#30932
     (http://bugs.mysql.com/30932)

   * *Replication*: Issuing a `DROP VIEW' statement caused replication
     to fail if the view did not actually exist.  (Bug#30998
     (http://bugs.mysql.com/30998))

   * *Replication*: The effects of scheduled events were not always
     correctly reproduced on the slave when using row-based replication.
     (Bug#29020 (http://bugs.mysql.com/29020))

   * *Replication*: Setting `server_id' did not update its value for
     the current session.  (Bug#28908 (http://bugs.mysql.com/28908))

   * *Replication*: Some older servers wrote events to the binary log
     using different numbering from what is currently used, even though
     the file format number in the file is the same. Slaves running
     MySQL 5.1.18 and later could not read these binary logs properly.
     Binary logs from these older versions now are recognized and event
     numbers are mapped to the current numbering so that they can be
     interpreted properly.  (Bug#27779 (http://bugs.mysql.com/27779),
     Bug#32434 (http://bugs.mysql.com/32434)) This regression was
     introduced by Bug#22583 (http://bugs.mysql.com/22583)

   * *Replication*: `MASTER_POS_WAIT()' did not return `NULL' when the
     server was not a slave.  (Bug#26622 (http://bugs.mysql.com/26622))

   * *Replication*: The inspecific error message `Wrong parameters to
     function register_slave' resulted when `START SLAVE' failed to
     register on the master due to excess length of any the slave
     server options `--report-host', `--report-user', or
     `--report-password'. An error message specific to each of these
     options is now returned in such cases. The new error messages are:

        * `Failed to register slave: too long 'report-host''

        * `Failed to register slave: too long 'report-user''

        * `Failed to register slave; too long 'report-password''

     (Bug#22989 (http://bugs.mysql.com/22989)) See also Bug#19328
     (http://bugs.mysql.com/19328)

   * *Replication*: `START SLAVE UNTIL MASTER_LOG_POS=POSITION' issued
     on a slave that was using `--log-slave-updates' and that was
     involved in circular replication would cause the slave to run and
     stop one event later than that specified by the value of POSITION.
     (Bug#13861 (http://bugs.mysql.com/13861))

   * *Replication*: `PURGE BINARY LOGS TO' and `PURGE BINARY LOGS
     BEFORE' did not handle missing binary log files correctly or in
     the same way. Now for both of these statements, if any files
     listed in the `.index' file are missing from the filesystem, the
     statement fails with an error.

   * Manually replacing a binary log file with a directory having the
     same name caused an error that was not handled correctly.
     (Bug#35675 (http://bugs.mysql.com/35675))

   * Using `LOAD DATA INFILE' with a view could crash the server.
     (Bug#35469 (http://bugs.mysql.com/35469))

   * Selecting from `INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS' could
     cause a server crash.  (Bug#35406 (http://bugs.mysql.com/35406))
     See also Bug#35108 (http://bugs.mysql.com/35108)

   * For a `TERMPORARY' table, `DELETE' with no `WHERE' clause could
     fail when preceded by `DELETE' statements with a `WHERE' clause.
     (Bug#35392 (http://bugs.mysql.com/35392))

   * If the server crashed with an `InnoDB' error due to unavailability
     of undo slots, errors could persist during rollback when the
     server was restarted: There are two `UNDO' slot caches (for
     `INSERT' and `UPDATE'). If all slots end up in one of the slot
     caches, a request for a slot from the other slot cache would fail.
     This can happen if the request is for an `UPDATE' slot and all
     slots are in the `INSERT' slot cache, or vice versa.  (Bug#35352
     (http://bugs.mysql.com/35352))

   * In some cases, when too many clients tried to connect to the
     server, the proper `SQLSTATE' code was not returned.  (Bug#35289
     (http://bugs.mysql.com/35289))

   * Memory-allocation failures for attempts to set `key_buffer_size'
     to large values could result in a server crash.  (Bug#35272
     (http://bugs.mysql.com/35272))

   * When using row-based replication, a slave could crash at startup
     because it received a row-based replication event that `InnoDB'
     could not handle due to an incorrect test of the query string
     provided by MySQL, which was `NULL' for row-based replication
     events.  (Bug#35226 (http://bugs.mysql.com/35226))

   * For `InnoDB' tables, `ALTER TABLE DROP' failed if the name of the
     column to be dropped began with `foreign'.  (Bug#35220
     (http://bugs.mysql.com/35220))

   * Queries could return different results depending on whether `ORDER
     BY' columns were indexed.  (Bug#35206
     (http://bugs.mysql.com/35206))

   * When a view containing a reference to `DUAL' was created, the
     reference was removed when the definition was stored, causing some
     queries against the view to fail with invalid SQL syntax errors.
     (Bug#35193 (http://bugs.mysql.com/35193))

   * `SELECT ... FROM INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS'
     caused the server to crash if the table referenced by a foreign
     key had been dropped. This issue was observed on Windows platforms
     only.  (Bug#35108 (http://bugs.mysql.com/35108)) See also
     Bug#35406 (http://bugs.mysql.com/35406)

   * Debugging symbols were missing for some executables in Windows
     binary distributions.  (Bug#35104 (http://bugs.mysql.com/35104))

   * Non-connection threads were being counted in the value of the
     `Max_used_connections' status variable.  (Bug#35074
     (http://bugs.mysql.com/35074))

   * A query that performed a `ref_or_null' join where the second table
     used a key having one or columns that could be `NULL' and had a
     column value that was `NULL' caused the server to crash.
     (Bug#34945 (http://bugs.mysql.com/34945)) This regression was
     introduced by Bug#12144 (http://bugs.mysql.com/12144)

   * For some queries, the optimizer used an ordered index scan for
     `GROUP BY' or `DISTINCT' when it was supposed to use a loose index
     scan, leading to incorrect results.  (Bug#34928
     (http://bugs.mysql.com/34928))

   * Creating a foreign key on an `InnoDB' table that was created with
     an explicit `AUTO_INCREMENT' value caused that value to be reset
     to 1.  (Bug#34920 (http://bugs.mysql.com/34920))

   * `mysqldump' failed to return an error code when using the
     `--master-data' option without binary logging being enabled on the
     server.  (Bug#34909 (http://bugs.mysql.com/34909))

   * Under some circumstances, the value of *Note `mysql_insert_id()':
     mysql-insert-id. following a `SELECT ... INSERT' statement could
     return an incorrect value. This could happen when the last `SELECT
     ... INSERT' did not involve an `AUTO_INCREMENT' column, but the
     value of *Note `mysql_insert_id()': mysql-insert-id. was changed
     by some previous statements.  (Bug#34889
     (http://bugs.mysql.com/34889))

   * Table and database names were mixed up in some places of the
     subquery transformation procedure. This could affect debugging
     trace output and further extensions of that procedure.  (Bug#34830
     (http://bugs.mysql.com/34830))

   * If `fsync()' returned `ENOLCK', `InnoDB' could treat this as fatal
     and cause abnormal server termination.  `InnoDB' now retries the
     operation.  (Bug#34823 (http://bugs.mysql.com/34823))

   * `CREATE SERVER' and `ALTER SERVER' could crash the server if
     out-of-memory conditions occurred.  (Bug#34790
     (http://bugs.mysql.com/34790))

   * `DROP SERVER' does not release memory cached for server structures
     created by `CREATE SERVER', so repeated iterations of these
     statements resulted in a memory leak. `FLUSH PRIVILEGES' now
     releases the memory allocated for `CREATE SERVER'.  (Bug#34789
     (http://bugs.mysql.com/34789))

   * A malformed URL used for a `FEDERATED' table's `CONNECTION' option
     value in a `CREATE TABLE' statement was not handled correctly and
     could crash the server.  (Bug#34788 (http://bugs.mysql.com/34788))

   * Queries such as `SELECT ROW(1, 2) IN (SELECT t1.a, 2) FROM t1
     GROUP BY t1.a' (combining row constructors and subqueries in the
     `FROM' clause) could lead to assertion failure or unexpected error
     messages.  (Bug#34763 (http://bugs.mysql.com/34763))

   * Using `NAME_CONST()' with a negative number and an aggregate
     function caused MySQL to crash. This could also have a negative
     impact on replication.  (Bug#34749 (http://bugs.mysql.com/34749))

   * A memory-handling error associated with use of `GROUP_CONCAT()' in
     subqueries could result in a server crash.  (Bug#34747
     (http://bugs.mysql.com/34747))

   * For an indexed integer column COL_NAME and a value N that is one
     greater than the maximum value allowed for the data type of
     COL_NAME, conditions of the form `WHERE COL_NAME < N' failed to
     return rows where the value of COL_NAME is `N - 1'.  (Bug#34731
     (http://bugs.mysql.com/34731))

   * A server running with the `--debug' option could attempt to
     dereference a null pointer when opening tables, resulting in a
     crash.  (Bug#34726 (http://bugs.mysql.com/34726))

   * Assigning an `incremental' value to the `debug' system variable
     did not add the new value to the current value. For example, if
     the current `debug' value was `'T'', the statement `SET debug =
     '+P'' resulted in a value of `'P'' rather than the correct value of
     `'P:T''.  (Bug#34678 (http://bugs.mysql.com/34678))

   * For debug builds, reading from `INFORMATION_SCHEMA.TABLES' or
     `INFORMATION_SCHEMA.COLUMNS' could cause assertion failures. This
     could happen under rare circumstances when `INFORMATION_SCHEMA'
     fails to get information about a table (for example, when a
     connection is killed).  (Bug#34656 (http://bugs.mysql.com/34656))

   * Executing a `TRUNCATE' statement on a table having both a foreign
     key reference and a `DELETE' trigger crashed the server.
     (Bug#34643 (http://bugs.mysql.com/34643))

   * Some subqueries using an expression that included an aggregate
     function could fail or in some cases lead to a crash of the server.
     (Bug#34620 (http://bugs.mysql.com/34620))

   * Dangerous pointer arithmetic crashed the server on some systems.
     (Bug#34598 (http://bugs.mysql.com/34598))

   * Creating a view inside a stored procedure could lead to a crash of
     the MySQL Server.  (Bug#34587 (http://bugs.mysql.com/34587))

   * A server crash could occur if `INFORMATION_SCHEMA' tables built in
     memory were swapped out to disk during query execution.
     (Bug#34529 (http://bugs.mysql.com/34529))

   * `CAST(AVG(ARG) AS DECIMAL)' produced incorrect results for
     non-`DECIMAL' arguments.  (Bug#34512 (http://bugs.mysql.com/34512))

   * The per-thread debugging settings stack was not being deallocated
     before thread termination, resulting in a stack memory leak.
     (Bug#34424 (http://bugs.mysql.com/34424))

   * Executing an `ALTER VIEW' statement on a table crashed the server.
     (Bug#34337 (http://bugs.mysql.com/34337))

   * `InnoDB' could crash if overflow occurred for an `AUTO_INCREMENT'
     column.  (Bug#34335 (http://bugs.mysql.com/34335))

   * For `InnoDB', exporting and importing a table could corrupt
     `TINYBLOB' columns, and a subsequent `ALTER TABLE' could corrupt
     `TINYTEXT' columns as well.  (Bug#34300
     (http://bugs.mysql.com/34300))

   * `DEFAULT 0' was not allowed for the `YEAR' data type.  (Bug#34274
     (http://bugs.mysql.com/34274))

   * Under some conditions, a `SET GLOBAL innodb_commit_concurrency' or
     `SET GLOBAL innodb_autoextend_increment' statement could fail.
     (Bug#34223 (http://bugs.mysql.com/34223))

   * `mysqldump' attempts to set the `character_set_results' system
     variable after connecting to the server. This failed for pre-4.1
     servers that have no such variable, but `mysqldump' did not
     account for this and 1) failed to dump database contents; 2)
     failed to produce any error message alerting the user to the
     problem.  (Bug#34192 (http://bugs.mysql.com/34192))

   * Use of stored functions in the `WHERE' clause for `SHOW OPEN
     TABLES' caused a server crash.  (Bug#34166
     (http://bugs.mysql.com/34166))

   * For a `FEDERATED' table with an index on a nullable column,
     accessing the table could crash a server, return an incorrect
     result set, or return `ERROR 1030 (HY000): Got error 1430 from
     storage engine'.  (Bug#33946 (http://bugs.mysql.com/33946))

   * Passing anything other than a integer to a `LIMIT' clause in a
     prepared statement would fail. (This limitation was introduced to
     avoid replication problems; for example, replicating the statement
     with a string argument would cause a parse failure in the slave).
     Now, arguments to the `LIMIT' clause are converted to integer
     values, and these converted values are used when logging the
     statement.  (Bug#33851 (http://bugs.mysql.com/33851))

   * An internal buffer in `mysql' was too short.  Overextending it
     could cause stack problems or segmentation violations on some
     architectures. (This is not a problem that could be exploited to
     run arbitrary code.)  (Bug#33841 (http://bugs.mysql.com/33841))

   * A query using `WHERE (column1='STRING1' AND column2=CONSTANT1) OR
     (column1='STRING2' AND column2=CONSTANT2)', where `col1' used a
     binary collation and STRING1 matched STRING2 except for case,
     failed to match any records even when matches were found by a
     query using the equivalent clause `WHERE column2=CONSTANT1 OR
     column2=CONSTANT2'.  (Bug#33833 (http://bugs.mysql.com/33833))

   * Large unsigned integers were improperly handled for prepared
     statements, resulting in truncation or conversion to negative
     numbers.  (Bug#33798 (http://bugs.mysql.com/33798))

   * Reuse of prepared statements could cause a memory leak in the
     embedded server.  (Bug#33796 (http://bugs.mysql.com/33796))

   * The server crashed when executing a query that had a subquery
     containing an equality X=Y where Y referred to a named select list
     expression from the parent select. The server crashed when trying
     to use the X=Y equality for `ref'-based access.  (Bug#33794
     (http://bugs.mysql.com/33794))

   * Some queries using a combination of `IN', `CONCAT()', and an
     implicit type conversion could return an incorrect result.
     (Bug#33764 (http://bugs.mysql.com/33764))

   * In some cases a query that produced a result set when using `ORDER
     BY ASC' did not return any results when this was changed to `ORDER
     BY DESC'.  (Bug#33758 (http://bugs.mysql.com/33758))

   * Disabling concurrent inserts caused some cacheable queries not to
     be saved in the query cache.  (Bug#33756
     (http://bugs.mysql.com/33756))

   * The UPDATE statement allowed `NULL' to be assigned to `NOT NULL'
     columns (the default data type value was assigned). An error
     occurs now.  (Bug#33699 (http://bugs.mysql.com/33699))

   * `ORDER BY ... DESC' sorts could produce misordered results.
     (Bug#33697 (http://bugs.mysql.com/33697))

   * The server could crash when `REPEAT' or another control
     instruction was used in conjunction with labels and a `LEAVE'
     instruction.  (Bug#33618 (http://bugs.mysql.com/33618))

   * The parser allowed control structures in compound statements to
     have mismatched beginning and ending labels.  (Bug#33618
     (http://bugs.mysql.com/33618))

   * `make_binary_distribution' passed the `--print-libgcc-file' option
     to the C compiler, but this does not work with the `ICC' compiler.
     (Bug#33536 (http://bugs.mysql.com/33536))

   * Threads created by the event scheduler were incorrectly counted
     against the `max_connections' thread limit, which could lead to
     client lockout.  (Bug#33507 (http://bugs.mysql.com/33507))

   * Dropping a function after dropping the function's creator could
     cause the server to crash.  (Bug#33464
     (http://bugs.mysql.com/33464))

   * Certain combinations of views, subselects with outer references
     and stored routines or triggers could cause the server to crash.
     (Bug#33389 (http://bugs.mysql.com/33389))

   * `SET GLOBAL myisam_max_sort_file_size=DEFAULT' set
     `myisam_max_sort_file_size' to an incorrect value.  (Bug#33382
     (http://bugs.mysql.com/33382)) See also Bug#31177
     (http://bugs.mysql.com/31177)

   * `ENUM'- or `SET'-valued plugin variables could not be set from the
     command line.  (Bug#33358 (http://bugs.mysql.com/33358))

   * For `InnoDB' tables, there was a race condition involving the data
     dictionary and repartitioning.  (Bug#33349
     (http://bugs.mysql.com/33349))

   * Loading plugins via command-line options to `mysqld' could cause
     an assertion failure.  (Bug#33345 (http://bugs.mysql.com/33345))

   * `SLEEP(0)' failed to return on 64-bit Mac OS X due to a bug in
     `pthread_cond_timedwait()'.  (Bug#33304
     (http://bugs.mysql.com/33304))

   * Using `Control-R' in the `mysql' client caused it to crash.
     (Bug#33288 (http://bugs.mysql.com/33288))

   * For `MyISAM' tables, `CHECK TABLE' (non-`QUICK') and any form of
     `REPAIR TABLE' incorrected treated rows as corrupted under the
     combination of the following conditions:

        * The table had dynamic row format

        * The table had a `CHAR' (not `VARCHAR') column longer than 127
          bytes (for multi-byte character sets this could be less than
          127 characters)

        * The table had rows with a signifcant length of more than 127
          bytes significant length in that `CHAR' column (that is, a
          byte beyond byte position 127 must be a non-space character)

     This problem affected `CHECK TABLE', `REPAIR TABLE', `OPTIMIZE
     TABLE', `ALTER TABLE'. `CHECK TABLE' reported and marked the table
     as crashed if any row was present that fulfilled the third
     condition. The other statements deleted these rows.  (Bug#33222
     (http://bugs.mysql.com/33222))

   * Granting the `UPDATE' privilege on one column of a view caused the
     server to crash.  (Bug#33201 (http://bugs.mysql.com/33201))

   * For `DECIMAL' columns used with the `ROUND(X,D)' or `TRUNCATE(X,D)'
     function with a non-constant value of D, adding an `ORDER BY' for
     the function result produced misordered output.  (Bug#33143
     (http://bugs.mysql.com/33143)) See also Bug#33402
     (http://bugs.mysql.com/33402), Bug#30617
     (http://bugs.mysql.com/30617)

   * The `CSV' engine did not honor update requests for `BLOB' columns
     when the new column value had the same length as the value to be
     updated.  (Bug#33067 (http://bugs.mysql.com/33067))

   * After receiving a `SIGHUP' signal, the server could crash, and
     user-specified log options were ignored when reopening the logs.
     (Bug#33065 (http://bugs.mysql.com/33065))

   * When MySQL was built with OpenSSL, the SSL library was not
     properly initialized with information of which endpoint it was
     (server or client), causing connection failures.  (Bug#33050
     (http://bugs.mysql.com/33050))

   * Under some circumstances a combination of aggregate functions and
     `GROUP BY' in a `SELECT' query over a view could lead to incorrect
     calculation of the result type of the aggregate function. This in
     turn could lead to incorrect results, or to crashes on debug
     builds of the server.  (Bug#33049 (http://bugs.mysql.com/33049))

   * For `DISTINCT' queries, 4.0 and 4.1 stopped reading joined tables
     as soon as the first matching row was found. However, this
     optimzation was lost in MySQL 5.0, which instead read all matching
     rows. This fix for this regression may result in a major
     improvement in performance for `DISTINCT' queries in cases where
     many rows match.  (Bug#32942 (http://bugs.mysql.com/32942))

   * Repeated creation and deletion of views within prepared statements
     could eventually crash the server.  (Bug#32890
     (http://bugs.mysql.com/32890)) See also Bug#34587
     (http://bugs.mysql.com/34587)

   * Incorrect assertions could cause a server crash for `DELETE'
     triggers for transactional tables.  (Bug#32790
     (http://bugs.mysql.com/32790))

   * In some cases where setting a system variable failed, no error was
     sent to the client, causing the client to hang.  (Bug#32757
     (http://bugs.mysql.com/32757))

   * Enabling the `PAD_CHAR_TO_FULL_LENGTH' SQL mode caused
     privilege-loading operations (such as `FLUSH PRIVILEGES') to
     include trailing spaces from grant table values stored in `CHAR'
     columns.  Authentication for incoming connections failed as a
     result. Now privilege loading does not include trailing spaces,
     regardless of SQL mode.  (Bug#32753 (http://bugs.mysql.com/32753))

   * The `SHOW ENGINE INNODB STATUS' and `SHOW ENGINE INNODB MUTEX'
     statements incorrectly required the `SUPER' privilege rather than
     the `PROCESS' privilege.  (Bug#32710 (http://bugs.mysql.com/32710))

   * Inserting strings with a common prefix into a table that used the
     `ucs2' character set corrupted the table.  (Bug#32705
     (http://bugs.mysql.com/32705))

   * Tables in the `mysql' database that stored the current `sql_mode'
     value as part of stored program definitions were not updated with
     newer mode values (`NO_ENGINE_SUBSTITUTION',
     `PAD_CHAR_TO_FULL_LENGTH'). This causes various problems defining
     stored programs if those modes were included in the current
     `sql_mode' value.  (Bug#32633 (http://bugs.mysql.com/32633))

   * A view created with a string literal for one of the columns picked
     up the connection character set, but not the collation.
     Comparison to that field therefore used the default collation for
     that character set, causing an error if the connection collation
     was not compatible with the default collation. The problem was
     caused by text literals in a view being dumped with a character
     set introducer even when this was not necessary, sometimes leading
     to a loss of collation information. Now the character set
     introducer is dumped only if it was included in the original query.
     (Bug#32538 (http://bugs.mysql.com/32538)) See also Bug#21505
     (http://bugs.mysql.com/21505)

   * Queries using `LIKE' on tables having indexed `CHAR' columns using
     either of the `eucjpms' or `ujis' character sets did not return
     correct results.  (Bug#32510 (http://bugs.mysql.com/32510))

   * Executing a prepared statement associated with a materialized
     cursor sent to the client a metadata packet with incorrect table
     and database names. The problem occurred because the server sent
     the the name of the temporary table used by the cursor instead of
     the table name of the original table.

     The same problem occured when selecting from a view, in which case
     the name of the table name was sent, rather than the name of the
     view.  (Bug#32265 (http://bugs.mysql.com/32265))

   * `InnoDB' adaptive hash latches could be held too long, resulting
     in a server crash. This fix may also provide significant
     performance improvements on systems on which many queries using
     filesorts with temporary tables are being performed.  (Bug#32149
     (http://bugs.mysql.com/32149))

   * On Windows, `mysqltest_embedded.exe' did not properly execute the
     `send' command.  (Bug#32044 (http://bugs.mysql.com/32044))

   * A variable named `read_only' could be declared even though that is
     a reserved word.  (Bug#31947 (http://bugs.mysql.com/31947))

   * On Windows, the build process failed with four parallel build
     threads.  (Bug#31929 (http://bugs.mysql.com/31929))

   * Queries testing numeric constants containing leading zeroes
     against `ZEROFILL' columns were not evaluated correctly.
     (Bug#31887 (http://bugs.mysql.com/31887))

   * If an error occurred during file creation, the server sometimes
     did not remove the file, resulting in an unused file in the
     filesystem.  (Bug#31781 (http://bugs.mysql.com/31781))

   * The `mysqld' crash handler failed on Windows.  (Bug#31745
     (http://bugs.mysql.com/31745))

   * When upgrading from MySQL 5.1.19 to any version between MySQL
     5.1.20 to MySQL 5.1.23, the MySQL Instance Configuration Wizard
     would fail to account for the change in name for the
     `mysqld-nt.exe' to `mysqld.exe', causing MySQL to fail to start
     properly after the upgrade.  (Bug#31674
     (http://bugs.mysql.com/31674))

   * The server returned the error message `Out of memory; restart
     server and try again' when the actual problem was that the sort
     buffer was too small. Now an appropriate error message is returned
     in such cases.  (Bug#31590 (http://bugs.mysql.com/31590))

   * A table having an index that included a `BLOB' or `TEXT' column,
     and that was originally created with a MySQL server using version
     4.1 or earlier, could not be opened by a 5.1 or later server.
     (Bug#31331 (http://bugs.mysql.com/31331))

   * The `-', `*', and `/' operators and the functions `POW()' and
     `EXP()' could misbehave when used with floating-point numbers.
     Previously they might return `+INF', `-INF', or `NaN' in cases of
     numeric overflow (including that caused by division by zero) or
     when invalid arguments were used. Now `NULL' is returned in all
     such cases.  (Bug#31236 (http://bugs.mysql.com/31236))

   * The *Note `mysql_change_user()': mysql-change-user. C API function
     caused global `Com_XXX' status variable values to be incorrect.
     (Bug#31222 (http://bugs.mysql.com/31222))

   * When sorting privilege table rows, the server treated escaped
     wildcard characters (`\%' and `\_') the same as unescaped wildcard
     characters (`%' and `_'), resulting in incorrect row ordering.
     (Bug#31194 (http://bugs.mysql.com/31194))

   * On Windows, `SHOW PROCESSLIST' could display process entries with
     a `State' value of `*** DEAD ***'.  (Bug#30960
     (http://bugs.mysql.com/30960))

   * `ROUND(X,D)' or `TRUNCATE(X,D)' for non-constant values of D could
     crash the server if these functions were used in an `ORDER BY'
     that was resolved using `filesort'.  (Bug#30889
     (http://bugs.mysql.com/30889))

   * Resetting the query cache by issuing a `SET GLOBAL
     query_cache_size=0' statement caused the server to crash if it
     concurrently was saving a new result set to the query cache.
     (Bug#30887 (http://bugs.mysql.com/30887))

   * Manifest problems prevented `MySQLInstanceConfig.exe' from running
     on Windows Vista.  (Bug#30823 (http://bugs.mysql.com/30823))

   * If an alias was used to refer to the value returned by a stored
     function within a subselect, the outer select recognized the alias
     but failed to retrieve the value assigned to it in the subselect.
     (Bug#30787 (http://bugs.mysql.com/30787))

   * Binary logging for a stored procedure differed depending on
     whether or not execution occurred in a prepared statement.
     (Bug#30604 (http://bugs.mysql.com/30604))

   * Replication of `LOAD DATA INFILE' could fail when
     `read_buffer_size' was larger than `max_allowed_packet'.
     (Bug#30435 (http://bugs.mysql.com/30435))

   * An orphaned PID file from a no-longer-running process could cause
     `mysql.server' to wait for that process to exit even though it
     does not exist.  (Bug#30378 (http://bugs.mysql.com/30378))

   * The `Table_locks_waited' waited variable was not incremented in
     the cases that a lock had to be waited for but the waiting thread
     was killed or the request was aborted.  (Bug#30331
     (http://bugs.mysql.com/30331))

   * The `Com_create_function' status variable was not incremented
     properly.  (Bug#30252 (http://bugs.mysql.com/30252))

   * View metadata returned from `INFORMATION_SCHEMA.VIEWS' was changed
     by the fix for Bug#11986 (http://bugs.mysql.com/11986), causing
     the information returned in MySQL 5.1 to differ from that returned
     in 5.0.  (Bug#30217 (http://bugs.mysql.com/30217))

   * `mysqld' displayed the `--enable-pstack' option in its help
     message even if MySQL was configured without `--with-pstack'.
     (Bug#29836 (http://bugs.mysql.com/29836))

   * The `mysql_config' command would output `CFLAGS' values that were
     incompatible with C++ for the HP-UX platform.  (Bug#29645
     (http://bugs.mysql.com/29645))

   * Replication crashed with the `NDB' storage engine when `mysqld'
     was started with `--character-set-server=ucs2'.  (Bug#29562
     (http://bugs.mysql.com/29562))

   * Views were treated as insertable even if some base table columns
     with no default value were omitted from the view definition.
     (This is contrary to the condition for insertability that a view
     must contain all columns in the base table that do not have a
     default value.)  (Bug#29477 (http://bugs.mysql.com/29477))

   * `myisamchk' always reported the character set for a table as
     `latin1_swedish_ci (8)' regardless of the table' actual character
     set.  (Bug#29182 (http://bugs.mysql.com/29182))

   * `InnoDB' could return an incorrect rows-updated value for `UPDATE'
     statements.  (Bug#29157 (http://bugs.mysql.com/29157))

   * The MySQL preferences pane did not work to start or stop MySQL on
     Mac OS X 10.5 (Leopard).  (Bug#28854 (http://bugs.mysql.com/28854))

   * For upgrading to a new major version using RPM packages (such as
     4.1 to 5.0), if the installation procedure found an existing MySQL
     server running, it could fail to shut down the old server, but
     also erroneously removed the server's socket file. Now the
     procedure checks for an existing server package from a different
     vendor or major MySQL version. In such case, it refuses to install
     the server and recommends how to safely remove the old packages
     before installing the new ones.  (Bug#28555
     (http://bugs.mysql.com/28555))

   * `mysqlhotcopy' silently skipped databases with names consisting of
     two alphanumeric characters.  (Bug#28460
     (http://bugs.mysql.com/28460))

   * No information was written to the general query log for the
     `COM_STMT_CLOSE', `COM_STMT_RESET', and `COM_STMT_SEND_LONG_DATA'
     commands. (These occur when a client invokes the *Note
     `mysql_stmt_close()': mysql-stmt-close, *Note
     `mysql_stmt_reset()': mysql-stmt-reset. and *Note
     `mysql_stmt_send_long_data()': mysql-stmt-send-long-data. C API
     functions.)  (Bug#28386 (http://bugs.mysql.com/28386))

   * Previously, the parser accepted the ODBC `{ OJ ... LEFT OUTER JOIN
     ...}' syntax for writing left outer joins.  The parser now allows
     `{ OJ ... }' to be used to write other types of joins, such as
     `INNER JOIN' or `RIGHT OUTER JOIN'. This helps with compatibility
     with some third-party applications, but is not official ODBC
     syntax.  (Bug#28317 (http://bugs.mysql.com/28317))

   * The `FEDERATED' storage engine did not perform identifier quoting
     for column names that are reserved words when sending statements
     to the remote server.  (Bug#28269 (http://bugs.mysql.com/28269))

   * The SQL parser did not accept an empty `UNION=()' clause. This
     meant that, when there were no underlying tables specified for a
     `MERGE' table, `SHOW CREATE TABLE' and `mysqldump' both output
     statements that could not be executed.

     Now it is possible to execute a `CREATE TABLE' or `ALTER TABLE'
     statement with an empty `UNION=()' clause. However, `SHOW CREATE
     TABLE' and `mysqldump' do not output the `UNION=()' clause if
     there are no underlying tables specified for a `MERGE' table. This
     also means it is now possible to remove the underlying tables for
     a `MERGE' table using `ALTER TABLE ... UNION=()'.  (Bug#28248
     (http://bugs.mysql.com/28248))

   * It was possible to exhaust memory by repeatedly running
     `index_merge' queries and never performing any `FLUSH TABLES'
     statements.  (Bug#27732 (http://bugs.mysql.com/27732))

   * When `utf8' was set as the connection character set, using
     `SPACE()' with a non-Unicode column produced an error.  (Bug#27580
     (http://bugs.mysql.com/27580)) See also Bug#23637
     (http://bugs.mysql.com/23637)

   * The parser rules for the `SHOW PROFILE' statement were revised to
     work with older versions of `bison'.  (Bug#27433
     (http://bugs.mysql.com/27433))

   * `resolveip' failed to produce correct results for hostnames that
     begin with a digit.  (Bug#27427 (http://bugs.mysql.com/27427))

   * In `ORDER BY' clauses, mixing aggregate functions and non-grouping
     columns is not allowed if the `ONLY_FULL_GROUP_BY' SQL mode is
     enabled.  However, in some cases, no error was thrown because of
     insufficient checking.  (Bug#27219 (http://bugs.mysql.com/27219))

   * For the `--record_log_pos' option, `mysqlhotcopy' now determines
     the slave status information from the result of `SHOW SLAVE
     STATUS' by using the `Relay_Master_Log_File' and
     `Exec_Master_Log_Pos' values rather than the `Master_Log_File' and
     `Read_Master_Log_Pos' values. This provides a more accurate
     indication of slave execution relative to the master.  (Bug#27101
     (http://bugs.mysql.com/27101))

   * The MySQL Instance Configuration Wizard would not allow you to
     choose a service name, even though the criteria for the service
     name were valid. The code that checks the name has been updated to
     support the correct criteria of any string less than 256 character
     and not containing either a forward or backward slash character.
     (Bug#27013 (http://bugs.mysql.com/27013))

   * Memory corruption, a crash of the MySQL server, or both, could
     take place if a low-level I/O error occurred while an `ARCHIVE'
     table was being opened.  (Bug#26978 (http://bugs.mysql.com/26978))

   * `DROP DATABASE' failed for attempts to drop databases with names
     that contained the legacy `#mysql50#' name prefix.  (Bug#26703
     (http://bugs.mysql.com/26703))

   * `config-win.h' unconditionally defined `bool' as `BOOL', causing
     problems on systems where `bool' is 1 byte and `BOOL' is 4 bytes.
     (Bug#26461 (http://bugs.mysql.com/26461))

   * On Windows, for distributions built with debugging support,
     `mysql' could crash if the user typed Control-C.  (Bug#26243
     (http://bugs.mysql.com/26243))

   * The XPath `boolean()' function did not cast string and nodeset
     values correctly in some cases. It now returns `TRUE' for any
     non-empty string or nodeset and 0 for a `NULL' string, as specified
     in the XPath standard..  (Bug#26051 (http://bugs.mysql.com/26051))

   * When symbolic links were disabled, either with a server startup
     option or by enabling the `NO_DIR_IN_CREATE' SQL mode, `CREATE
     TABLE' silently ignored the `DATA DIRECTORY' and `INDEX DIRECTORY'
     table options. Now the server issues a warning if symbolic links
     are disabled when these table options are used.  (Bug#25677
     (http://bugs.mysql.com/25677))

   * Attempting to create an index with a prefix on a `DECIMAL' column
     appeared to succeed with an inaccurate warning message. Now, this
     action fails with the error `Incorrect prefix key; the used key
     part isn't a string, the used length is longer than the key part,
     or the storage engine doesn't support unique prefix keys'.
     (Bug#25426 (http://bugs.mysql.com/25426))

   * `mysqlcheck -A -r' did not correctly identify all tables that
     needed repairing.  (Bug#25347 (http://bugs.mysql.com/25347))

   * On Windows, an error in `configure.js' caused installation of
     source distributions to fail.  (Bug#25340
     (http://bugs.mysql.com/25340))

   * The `Qcache_free_blocks' status variable did not display a value
     of 0 if the query cache was disabled.  (Bug#25132
     (http://bugs.mysql.com/25132))

   * The client library had no way to return an error if no connection
     had been established. This caused problems such as *Note
     `mysql_library_init()': mysql-library-init. failing silently if no
     `errmsg.sys' file was available.  (Bug#25097
     (http://bugs.mysql.com/25097))

   * On Mac OS X, the StartupItem for MySQL did not work.  (Bug#25008
     (http://bugs.mysql.com/25008))

   * For Windows 64-bit builds, enabling shared-memory support caused
     client connections to fail.  (Bug#24992
     (http://bugs.mysql.com/24992))

   * `mysql' did not use its completion table. Also, the table
     contained few entries.  (Bug#24624 (http://bugs.mysql.com/24624))

   * If a user installed MySQL Server and set a password for the `root'
     user, and then uninstalled and reinstalled MySQL Server to the
     same location, the user could not use the MySQL Instance Config
     wizard to configure the server because the uninstall operation
     left the previous data directory intact. The config wizard
     _assumed_ that any new install (not an upgrade) would have the
     default data directory where the `root' user has no password. The
     installer now writes a registry key named `FoundExistingDataDir'.
     If the installer finds an existing data directory, the key will
     have a value of 1, otherwise it will have a value of 0. When
     `MySQLInstanceConfig.exe' is run, it will attempt to read the key.
     If it can read the key, and the value is 1 and there is no
     existing instance of the server (indicating a new installation),
     the Config Wizard will allow the user to input the old password so
     the server can be configured.  (Bug#24215
     (http://bugs.mysql.com/24215))

   * Logging of statements to log tables was incorrect for statements
     that contained `utf8'-incompatible binary strings. Incompatible
     sequences are hex-encoded now.  (Bug#23924
     (http://bugs.mysql.com/23924))

   * The MySQL header files contained some duplicate macro definitions
     that could cause compilation problems.  (Bug#23839
     (http://bugs.mysql.com/23839))

   * `SHOW COLUMNS' on a `TEMPOARY' table caused locking issues.
     (Bug#23588 (http://bugs.mysql.com/23588))

   * For distributions compiled with the bundled `libedit' library,
     there were difficulties using the `mysql' client to enter input for
     non-ASCII or multi-byte characters.  (Bug#23097
     (http://bugs.mysql.com/23097))

   * `perror' reported incomplete or inaccurate information.
     (Bug#23028 (http://bugs.mysql.com/23028), Bug#25177
     (http://bugs.mysql.com/25177))

   * `InnoDB' exhibited thread thrashing with more than 50 concurrent
     connections under an update-intensive workload.  (Bug#22868
     (http://bugs.mysql.com/22868))

   * After stopping and starting the event scheduler, disabled events
     could remain in the execution queue.  (Bug#22738
     (http://bugs.mysql.com/22738))

   * The server produced a confusing error message when attempting to
     open a table that required a storage engine that was not loaded.
     (Bug#22708 (http://bugs.mysql.com/22708))

   * For views or stored programs created with an invalid `DEFINER'
     value, the error message was confusing (did not tie the problem to
     the `DEFINER' clause) and has been improved.  (Bug#21854
     (http://bugs.mysql.com/21854))

   * Warnings for deprecated syntax constructs used in stored routines
     make sense to report only when the routine is being created, but
     they were also being reported when the routine was parsed for
     loading into the execution cache. Now they are reported only at
     routine creation time.  (Bug#21801 (http://bugs.mysql.com/21801))

   * Renaming a column that appeared in a foreign key definition did
     not update that definition with the new column name. This occurred
     with both referenced and referencing tables.  (Bug#21704
     (http://bugs.mysql.com/21704))

   * On Mac OS X, `mysqld' did not react to Ctrl-C when run under
     `gdb', even when run with the `--gdb' option.  (Bug#21567
     (http://bugs.mysql.com/21567))

   * `CREATE ... SELECT' did not always set `DEFAULT' column values in
     the new table.  (Bug#21380 (http://bugs.mysql.com/21380))

   * `mysql_config' output did not include `-lmygcc' on some platforms
     when it was needed.  (Bug#21158 (http://bugs.mysql.com/21158))

   * `mysql-stress-test.pl' and `mysqld_multi.server.sh' were missing
     from some binary distributions.  (Bug#21023
     (http://bugs.mysql.com/21023), Bug#25486
     (http://bugs.mysql.com/25486))

   * The `BENCHMARK()' function, invoked with more than 2147483648
     iterations (the size of a signed 32-bit integer), terminated
     prematurely.  (Bug#20752 (http://bugs.mysql.com/20752))

   * `mysqldumpslow' returned a confusing error message when no
     configuration file was found.  (Bug#20455
     (http://bugs.mysql.com/20455))

   * `MySQLInstanceConfig.exe' could lose the `innodb_data_home_dir'
     setting when reconfiguring an instance.  (Bug#19797
     (http://bugs.mysql.com/19797))

   * `DROP DATABASE' did not drop orphaned `FOREIGN KEY' constraints.
     (Bug#18942 (http://bugs.mysql.com/18942))

   * `CREATE TABLE' allowed 0 as the default value for a `TIMESTAMP'
     column when the server was running in `NO_ZERO_DATE' mode.
     (Bug#18834 (http://bugs.mysql.com/18834))

   * A `SET' column whose definition specified 64 elements could not be
     updated using integer values.  (Bug#15409
     (http://bugs.mysql.com/15409))

   * If a `SELECT' calls a stored function in a transaction, and a
     statement within the function fails, that statement should roll
     back. Furthermore, if `ROLLBACK' is executed after that, the entire
     transaction should be rolled back. Before this fix, the failed
     statement did not roll back when it failed (even though it might
     ultimately get rolled back by a `ROLLBACK' later that rolls back
     the entire transaction).  (Bug#12713 (http://bugs.mysql.com/12713))
     See also Bug#34655 (http://bugs.mysql.com/34655)

   * The parser incorrectly allowed `SQLSTATE '00000'' to be specified
     for a condition handler. (This is incorrect because the condition
     must be a failure condition and `'00000'' indicates success.)
     (Bug#8759 (http://bugs.mysql.com/8759))

   * `MySQLInstanceConfig.exe' did not save the `innodb_data_home_dir'
     value to the `my.ini' file under certain circumstances.  (Bug#6627
     (http://bugs.mysql.com/6627))


File: manual.info,  Node: news-5-1-23,  Next: news-5-1-22,  Prev: news-5-1-24,  Up: news-5-1-x

C.1.7 Changes in MySQL 5.1.23 (29 January 2008)
-----------------------------------------------

Functionality added or changed:

   * *Important Change*: *Partitioning*: *Security Fix*: It was
     possible, by creating a partitioned table using the `DATA
     DIRECTORY' and `INDEX DIRECTORY' options to gain privileges on
     other tables having the same name as the partitioned table. As a
     result of this fix, any table-level `DATA DIRECTORY' or `INDEX
     DIRECTORY' options are now ignored for partitioned tables.
     (Bug#32091 (http://bugs.mysql.com/32091), CVE-2007-5970
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-5970)) See
     also Bug#29325 (http://bugs.mysql.com/29325), Bug#32111
     (http://bugs.mysql.com/32111)

   * *Incompatible Change*: In MySQL 5.1.6, when log tables were
     implemented, the default log destination for the general query and
     slow query log was `TABLE'. This default has been changed to
     `FILE', which is compatible with MySQL 5.0, but incompatible with
     earlier releases of MySQL 5.1 from 5.1.6 to 5.1.20. If you are
     upgrading from MySQL 5.0 to this release, no logging option
     changes should be necessary. However, if you are upgrading from
     5.1.6 through 5.1.20 to this release and were using `TABLE'
     logging, use the `--log-output=TABLE' option explicitly to
     preserve your server's table-logging behavior.

     In MySQL 5.1.x, this bug was addressed twice because it turned out
     that the default was set in two places, only one of which was
     fixed the first time.  (Bug#29993 (http://bugs.mysql.com/29993))

   * *Incompatible Change*

     The parser accepted statements that contained `/* ...  */' that
     were not properly closed with `*/', such as `SELECT 1 /* + 2'.
     Statements that contain unclosed `/*'-comments now are rejected
     with a syntax error.

     This fix has the potential to cause incompatibilities. Because of
     Bug#26302 (http://bugs.mysql.com/26302), which caused the trailing
     `*/' to be truncated from comments in views, stored routines,
     triggers, and events, it is possible that objects of those types
     may have been stored with definitions that now will be rejected as
     syntactically invalid. Such objects should be dropped and
     re-created so that their definitions do not contain truncated
     comments.  (Bug#28779 (http://bugs.mysql.com/28779))

   * *MySQL Cluster*: The following improvements have been made in the
     `ndb_size.pl' utility:

        * The script can now be used with multiple databases; lists of
          databases and tables can also be excluded from analysis.

        * Schema name information has been added to index table
          calculations.

        * The database name is now an optional parameter, the exclusion
          of which causes all databases to be examined.

        * If selecting from `INFORMATION_SCHEMA' fails, the script now
          attempts to fall back to `SHOW TABLES'.

        * A `--real_table_name' option has been added; this designates
          a table to handle unique index size calculations.

        * The report title has been amended to cover cases where more
          than one database is being analyzed.

     Support for a `--socket' option was also added.

     For more information, see *Note mysql-cluster-utilities-ndb-size::.
     (Bug#28683 (http://bugs.mysql.com/28683), Bug#28253
     (http://bugs.mysql.com/28253))

   * *MySQL Cluster*: Mapping of `NDB' error codes to MySQL storage
     engine error codes has been improved.  (Bug#28423
     (http://bugs.mysql.com/28423))

   * *MySQL Cluster*: The output from the cluster management client
     showing the progress of data node starts has been improved.
     (Bug#23354 (http://bugs.mysql.com/23354))

   * *Partitioning*: Error messages for partitioning syntax errors have
     been made more descriptive.  (Bug#29368
     (http://bugs.mysql.com/29368))

   * *Replication*: Replication of the following SQL functions now
     switches to row-based logging in `MIXED' mode, and generates a
     warning in `STATEMENT' mode:

        * `USER()'

        * `CURRENT_USER()' and its alias `CURRENT_USER'

        * `FOUND_ROWS()'

        * `ROW_COUNT()'

     See *Note binary-log-mixed::, for more information.  (Bug#12092
     (http://bugs.mysql.com/12092), Bug#28086
     (http://bugs.mysql.com/28086), Bug#30244
     (http://bugs.mysql.com/30244))

   * `mysqltest' now has a `change_user' command to change the user for
     the current connection. (It invokes the *Note
     `mysql_change_user()': mysql-change-user. C API function.)
     (Bug#31608 (http://bugs.mysql.com/31608))

   * `mysql-test-run.pl' now allows a suite name prefix to be specified
     in command-line arguments that name test cases. The test name
     syntax now is `[SUITE_NAME.]TEST_NAME[.SUFFIX]'.  For example,
     `mysql-test-run.pl binlog.mytest' runs the `mytest.test' test in
     the `binlog' test suite.  (Bug#31400 (http://bugs.mysql.com/31400))

   * The `--event-scheduler' option without a value disabled the event
     scheduler. Now it enables the event scheduler.  (Bug#31332
     (http://bugs.mysql.com/31332))

   * `mysqldump' produces a `-- Dump completed on DATE' comment at the
     end of the dump if `--comments' is given.  The date causes dump
     files for identical data take at different times to appear to be
     different. The new options `--dump-date' and `--skip-dump-date'
     control whether the date is added to the comment.
     `--skip-dump-date' suppresses date printing. The default is
     `--dump-date' (include the date in the comment).  (Bug#31077
     (http://bugs.mysql.com/31077))

   * Server parser performance was improved for expression parsing by
     lowering the number of state transitions and reductions needed.
     (Bug#30625 (http://bugs.mysql.com/30625))

   * Server parser performance was improved for identifier lists,
     expression lists, and UDF expression lists.  (Bug#30333
     (http://bugs.mysql.com/30333))

   * Server parser performance was improved for boolean expressions.
     (Bug#30237 (http://bugs.mysql.com/30237))

   * The `LAST_EXECUTED' column of the `INFORMATION_SCHEMA.EVENTS'
     table now indicates when the event started executing rather than
     when it finished executing. As a result, the `ENDS' column is
     never less than `LAST_EXECUTED'.  (Bug#29830
     (http://bugs.mysql.com/29830))

   * The `mysql_odbc_escape_string()' C API function has been removed.
     It has multi-byte character escaping issues, doesn't honor the
     `NO_BACKSLASH_ESCAPES' SQL mode and is not needed anymore by
     Connector/ODBC as of 3.51.17.  (Bug#29592
     (http://bugs.mysql.com/29592))

   * If a `MyISAM' table is created with no `DATA DIRECTORY' option, the
     `.MYD' file is created in the database directory. By default, if
     `MyISAM' finds an existing `.MYD' file in this case, it overwrites
     it. The same applies to `.MYI' files for tables created with no
     `INDEX DIRECTORY' option. To suppress this behavior, start the
     server with the new `--keep_files_on_create' option, in which case
     `MyISAM' will not overwrite existing files and returns an error
     instead.  (Bug#29325 (http://bugs.mysql.com/29325))

   * The default value of the `connect_timeout' system variable was
     increased from 5 to 10 seconds. This might help in cases where
     clients frequently encounter errors of the form `Lost connection
     to MySQL server at 'XXX', system error: ERRNO'.  (Bug#28359
     (http://bugs.mysql.com/28359))

   * MySQL now can be compiled with `gcc' 4.2.x.  There was a problem
     involving a conflict with the `min()' and `max()' macros in
     `my_global.h'.  (Bug#28184 (http://bugs.mysql.com/28184))

   * The argument for the `mysql-test-run.pl' `--do-test' and
     `--skip-test' options is now interpreted as a Perl regular
     expression if there is a pattern metacharacter in the argument
     value. This allows more flexible specification of which tests to
     perform or skip.

Bugs fixed:

   * *Security Fix*: *Replication*: It was possible for any connected
     user to issue a `BINLOG' statement, which could be used to
     escalate privileges.

     Use of the `BINLOG' statement now requires the `SUPER' privilege.
     (Bug#31611 (http://bugs.mysql.com/31611), CVE-2007-6313
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-6313))

   * *Security Fix*: Three vulnerabilities in yaSSL versions 1.7.5 and
     earlier were discovered that could lead to a server crash or
     execution of unauthorized code. The exploit requires a server with
     yaSSL enabled and TCP/IP connections enabled, but does not require
     valid MySQL account credentials. The exploit does not apply to
     OpenSSL.

     *Note*:

     The proof-of-concept exploit is freely available on the Internet.
     Everyone with a vulnerable MySQL configuration is advised to
     upgrade _immediately_.

     (Bug#33814 (http://bugs.mysql.com/33814), CVE-2008-0226
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-0226),
     CVE-2008-0227
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-0227))

   * *Security Fix*: Using `RENAME TABLE' against a table with explicit
     `DATA DIRECTORY' and `INDEX DIRECTORY' options can be used to
     overwrite system table information by replacing the symbolic link
     points. the file to which the symlink points.

     MySQL will now return an error when the file to which the symlink
     points already exists.  (Bug#32111 (http://bugs.mysql.com/32111),
     CVE-2007-5969
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-5969))

   * *Security Fix*: `ALTER VIEW' retained the original `DEFINER'
     value, even when altered by another user, which could allow that
     user to gain the access rights of the view. Now `ALTER VIEW' is
     allowed only to the original definer or users with the `SUPER'
     privilege.  (Bug#29908 (http://bugs.mysql.com/29908))

   * *Security Fix*: When using a `FEDERATED' table, the local server
     could be forced to crash if the remote server returned a result
     with fewer columns than expected.  (Bug#29801
     (http://bugs.mysql.com/29801))

   * *Security Enhancement*: It was possible to force an error message
     of excessive length which could lead to a buffer overflow. This
     has been made no longer possible as a security precaution.
     (Bug#32707 (http://bugs.mysql.com/32707))

   * *Important Change*: *Incompatible Change*: A number of problems
     existed in the implementation of `MERGE' tables that could cause
     problems. The problems are summarized below:

        * Bug#26379 (http://bugs.mysql.com/26379) - Combination of
          `FLUSH TABLE' and `REPAIR TABLE' corrupts a `MERGE' table.
          This was caused in a number of situations:

            1. A thread trying to lock a `MERGE' table performs busy
               waiting while `REPAIR TABLE' or a similar table
               administration task is ongoing on one or more of its
               MyISAM tables.

            2. A thread trying to lock a `MERGE' table performs busy
               waiting until all threads that did `REPAIR TABLE' or
               similar table administration tasks on one or more of its
               MyISAM tables in LOCK TABLES segments do UNLOCK TABLES.
               The difference against problem #1 is that the busy
               waiting takes place after the administration task. It is
               terminated by `UNLOCK TABLES' only.

            3. Two `FLUSH TABLES' within a `LOCK TABLES' segment can
               invalidate the lock. This does not require a `MERGE'
               table. The first `FLUSH TABLES' can be replaced by any
               statement that requires other threads to reopen the
               table. In 5.0 and 5.1 a single `FLUSH TABLES' can provoke
               the problem.

        * Bug#26867 (http://bugs.mysql.com/26867) - Simultaneously
          executing `LOCK TABLES' and `REPAIR TABLE' on a `MERGE' table
          would result in memory/cpu hogging.

          Trying DML on a `MERGE' table, which has a child locked and
          repaired by another thread, made an infinite loop in the
          server.

        * Bug#26377 (http://bugs.mysql.com/26377) - Deadlock with
          `MERGE' and `FLUSH TABLE'

          Locking a MERGE table and its children in parent-child order
          and flushing the child deadlocked the server.

        * Bug#25038 (http://bugs.mysql.com/25038) - Waiting `TRUNCATE'

          Truncating a MERGE child, while the MERGE table was in use,
          let the truncate fail instead of waiting for the table to
          become free.

        * Bug#25700 (http://bugs.mysql.com/25700) - `MERGE' base tables
          get corrupted by `OPTIMIZE/ANALYZE/REPAIR TABLE'

          Repairing a child of an open `MERGE' table corrupted the
          child. It was necessary to `FLUSH' the child first.

        * Bug#30275 (http://bugs.mysql.com/30275) - `MERGE' tables:
          `FLUSH TABLES' or `UNLOCK TABLES' causes server to crash.

          Flushing and optimizing locked `MERGE' children crashed the
          server.

        * Bug#19627 (http://bugs.mysql.com/19627) - temporary merge
          table locking

          Use of a temporary `MERGE' table with non-temporary children
          could corrupt the children.

          Temporary tables are never locked. Creation of tables with
          non-temporary children of a temporary `MERGE' table is now
          prohibited.

        * Bug#27660 (http://bugs.mysql.com/27660) - `Falcon': `MERGE'
          table possible

          It was possible to create a `MERGE' table with non-`MyISAM'
          children.

        * Bug#30273 (http://bugs.mysql.com/30273) - `MERGE' tables:
          Can't lock file (errno: 155)

          This was a Windows-only bug. Table administration statements
          sometimes failed with "Can't lock file (errno: 155)".

     The fix introduces the following changes in behavior:

        * This patch changes the behavior of temporary `MERGE' tables.
          Temporary `MERGE' must have temporary children. The old
          behavior was wrong. A temporary table is not locked.  Hence
          even non-temporary children were not locked. See Bug#19627
          (http://bugs.mysql.com/19627).

        * You cannot change the union list of a non-temporary `MERGE'
          table when LOCK TABLES is in effect. The following does _not_
          work:

               CREATE TABLE m1 ... ENGINE=MRG_MYISAM ...;
               LOCK TABLES t1 WRITE, t2 WRITE, m1 WRITE;
               ALTER TABLE m1 ... UNION=(t1,t2) ...;

          However, you can do this with a temporary `MERGE' table.

        * You cannot create a `MERGE' table with `CREATE ... SELECT',
          neither as a temporary `MERGE' table, nor as a non-temporary
          `MERGE' table. For example, `CREATE TABLE m1 ...
          ENGINE=MRG_MYISAM ... SELECT ...;' causes the error message:
          `table is not BASE TABLE'.

     (Bug#19627 (http://bugs.mysql.com/19627), Bug#25038
     (http://bugs.mysql.com/25038), Bug#25700
     (http://bugs.mysql.com/25700), Bug#26377
     (http://bugs.mysql.com/26377), Bug#26379
     (http://bugs.mysql.com/26379), Bug#26867
     (http://bugs.mysql.com/26867), Bug#27660
     (http://bugs.mysql.com/27660), Bug#30275
     (http://bugs.mysql.com/30275), Bug#30491
     (http://bugs.mysql.com/30491))

   * *Incompatible Change*: It is no longer possible to create `CSV'
     tables with `NULL' columns. However, for backwards compatibility,
     you can continue to use such tables that were created in previous
     MySQL releases.  (Bug#32050 (http://bugs.mysql.com/32050))

   * *Incompatible Change*: With `ONLY_FULL_GROUP_BY' SQL mode enabled,
     queries such as `SELECT a FROM t1 HAVING COUNT(*)>2' were not
     being rejected as they should have been.

     This fix results in the following behavior:

        * There is a check against mixing group and non-group columns
          _only_ when `ONLY_FULL_GROUP_BY' is enabled.

        * This check is done both for the select list and for the
          `HAVING' clause if there is one.

     This behavior differs from previous versions as follows:

        * Previously, the `HAVING' clause was not checked when
          `ONLY_FULL_GROUP_BY' was enabled; now it is checked.

        * Previously, the select list was checked even when
          `ONLY_FULL_GROUP_BY' was not enabled; now it is checked only
          when `ONLY_FULL_GROUP_BY' is enabled.

     (Bug#31794 (http://bugs.mysql.com/31794))

   * *Incompatible Change*: Inserting a row with a `NULL' value for a
     `DATETIME' column results in a `CSV' file that the storage engine
     cannot read.

     All `CSV' tables now need to be defined with each column marked as
     `NOT NULL'. An error is raised if you try to create a `CSV' table
     with columns that are not defined with `NOT NULL'.  (Bug#31473
     (http://bugs.mysql.com/31473), Bug#32817
     (http://bugs.mysql.com/32817))

   * *Incompatible Change*: `SET PASSWORD' statements now cause an
     implicit commit, and thus are prohibited within stored functions
     and triggers.  (Bug#30904 (http://bugs.mysql.com/30904))

   * *Incompatible Change*: The `mysql_install_db' script could fail to
     locate some components (including `resolveip') during execution if
     the `--basedir' option was specified on the command-line or within
     the `my.cnf' file. This was due to a conflict when comparing the
     compiled-in values and the supplied values.

     The `--source-install' command-line option to the script has been
     removed and replaced with the `--srcdir' option.
     `mysql_install_db' now locates components either using the
     compiled-in options, the `--basedir' option or `--srcdir' option.
     (Bug#30759 (http://bugs.mysql.com/30759))

   * *Incompatible Change*: Multiple-table `DELETE' statements
     containing ambiguous aliases could have unintended side effects
     such as deleting rows from the wrong table. Example:

          DELETE FROM t1 AS a2 USING t1 AS a1 INNER JOIN t2 AS a2;

     Now alias declarations can be declared only in the
     TABLE_REFERENCES part. Elsewhere in the statement, alias
     references are allowed but not alias declarations. Statements
     containing aliases that are no longer allowed must be rewritten.
     (Bug#30234 (http://bugs.mysql.com/30234)) See also Bug#27525
     (http://bugs.mysql.com/27525)

   * *Incompatible Change*: Within a stored routine, it is no longer
     allowable to declare a cursor for a `SHOW' statement. This
     happened to work in some instances, but is no longer supported.
     (Bug#29223 (http://bugs.mysql.com/29223))

   * *Incompatible Change*: Several type-preserving functions and
     operators returned an incorrect result type that does not match
     their argument types: `COALESCE()', `IF()', `IFNULL()', `LEAST()',
     `GREATEST()', `CASE'. These now aggregate using the precise SQL
     types of their arguments rather than the internal type. In
     addition, the result type of the `STR_TO_DATE()' function is now
     `DATETIME' by default.  (Bug#27216 (http://bugs.mysql.com/27216))

   * *Incompatible Change*: `GRANT' and `REVOKE' statements now cause
     an implicit commit, and thus are prohibited within stored
     functions and triggers.  (Bug#21975 (http://bugs.mysql.com/21975),
     Bug#21422 (http://bugs.mysql.com/21422), Bug#17244
     (http://bugs.mysql.com/17244))

   * *Incompatible Change*: It was possible for option files to be read
     twice at program startup, if some of the standard option file
     locations turned out to be the same directory. Now duplicates are
     removed from the list of files to be read.

     Also, users could not override system-wide settings using
     `~/.my.cnf' because `SYSCONFDIR/my.cnf' was read last. The latter
     file now is read earlier so that `~/.my.cnf' can override
     system-wide settings.

     The fix for this problem had a side effect such that on Unix,
     MySQL programs looked for options in `~/my.cnf' rather than the
     standard location of `~/.my.cnf'. That problem was addressed as
     Bug#38180 (http://bugs.mysql.com/38180).  (Bug#20748
     (http://bugs.mysql.com/20748))

   * *Important Change*: *MySQL Cluster*: `AUTO_INCREMENT' columns had
     the following problems when used in `NDB' tables:

        * The `AUTO_INCREMENT' counter was not updated correctly when
          such a column was updated.

        * `AUTO_INCREMENT' values were not prefetched beyond statement
          boundaries.

        * `AUTO_INCREMENT' values were not handled correctly with
          `INSERT IGNORE' statements.

        * After being set, `ndb_autoincrement_prefetch_sz' showed a
          value of 1, regardless of the value it had actually been set
          to.

     As part of this fix, the behavior of
     `ndb_autoincrement_prefetch_sz' has changed.  Setting this to less
     than 32 no longer has any effect on prefetching within statements
     (where IDs are now always obtained in batches of 32 or more), but
     only between statements. The default value for this variable has
     also changed, and is now `1'.  (Bug#25176
     (http://bugs.mysql.com/25176), Bug#31956
     (http://bugs.mysql.com/31956), Bug#32055
     (http://bugs.mysql.com/32055))

   * *Partitioning*: *Important Note*: An apostrophe or single quote
     character (`'') used in the `DATA DIRECTORY', `INDEX DIRECTORY', or
     `COMMENT' for a `PARTITION' clause caused the server to crash.
     When used as part of a `CREATE TABLE' statement, the crash was
     immediate. When used in an `ALTER TABLE' statement, the crash did
     not occur until trying to perform a `SELECT' or DML statement on
     the table. In either case, the server could not be completely
     restarted until the `.FRM' file corresponding to the newly created
     or altered table was deleted.

     *Note*:

     Upgrading to the current (or later) release solves this problem
     only for tables that are newly created or altered.  Tables created
     or altered in previous versions of the server to include `''
     characters in `PARTITION' options must still be removed by
     deleting the corresponding `.FRM' files and re-creating them
     afterwards.

     (Bug#30695 (http://bugs.mysql.com/30695))

   * *Important Note*: The `RENAME DATABASE' statement was removed and
     replaced with `ALTER DATABASE DB_NAME UPGRADE DATA DIRECTORY
     NAME'. The `RENAME DATABASE' statement was intended for upgrading
     database directory names to the encoding format used in 5.1 for
     representing identifiers in the filesystem (see *Note
     identifier-mapping::).  However, the statement was found to be
     dangerous because it could result in loss of database contents. See
     *Note rename-database:: and *Note alter-database::.  (Bug#17565
     (http://bugs.mysql.com/17565), Bug#21741
     (http://bugs.mysql.com/21741), Bug#28360
     (http://bugs.mysql.com/28360))

   * *Replication*: *MySQL Cluster*: Row-based replication from or to a
     big-endian machine where the table used the `NDB' storage engine
     failed, if the same table on the other machine was either
     non-`NDB' or the other machine was little-endian.  (Bug#29549
     (http://bugs.mysql.com/29549), Bug#30790
     (http://bugs.mysql.com/30790)) See also Bug#24231
     (http://bugs.mysql.com/24231), Bug#30024
     (http://bugs.mysql.com/30024), Bug#30133
     (http://bugs.mysql.com/30133), Bug#30134
     (http://bugs.mysql.com/30134)

   * *MySQL Cluster*: An improperly reset internal signal was observed
     as a hang when using events in the `NDB' API but could result in
     various errors.  (Bug#33206 (http://bugs.mysql.com/33206))

   * *MySQL Cluster*: Incorrectly handled parameters could lead to a
     crash in the Transaction Coordinator during a node failure,
     causing other data nodes to fail.  (Bug#33168
     (http://bugs.mysql.com/33168))

   * *MySQL Cluster*: A memory leak occurred if a subscription start
     request was received by the subscription manager before the node
     making the request was fully connected to the cluster.  (Bug#32652
     (http://bugs.mysql.com/32652))

   * *MySQL Cluster*: A local checkpoint could sometimes be started
     before the previous LCP was restorable from a global checkpoint.
     (Bug#32519 (http://bugs.mysql.com/32519))

   * *MySQL Cluster*: High numbers of API nodes on a slow or congested
     network could cause connection negotiation to time out
     prematurely, leading to the following issues:

        * Excessive retries

        * Excessive CPU usage

        * Partially connected API nodes

     (Bug#32359 (http://bugs.mysql.com/32359))

   * *MySQL Cluster*: When a `mysqld' acting as a cluster SQL node
     starts the `NDBCLUSTER' storage engine, there is a delay during
     which some necessary data structures cannot be initialized until
     after it has connected to the cluster, and all MySQL Cluster
     tables should be opened as read-only. This worked correctly when
     the `NDB' binlog thread was running, but when it was not running,
     Cluster tables were not opened as read-only even when the data
     structures had not yet been set up.  (Bug#32275
     (http://bugs.mysql.com/32275), Bug#33763
     (http://bugs.mysql.com/33763))

   * *MySQL Cluster*: The failure of a master node could lead to
     subsequent failures in local checkpointing.  (Bug#32160
     (http://bugs.mysql.com/32160))

   * *MySQL Cluster*: The management server was slow to respond when no
     data nodes were connected to the cluster. This was most noticeable
     when running `SHOW' in the management client.  (Bug#32023
     (http://bugs.mysql.com/32023))

   * *MySQL Cluster*: An error with an `if' statement in
     `sql/ha_ndbcluster.cc' could potentially lead to an infinite loop
     in case of failure when working with `AUTO_INCREMENT' columns in
     `NDB' tables.  (Bug#31810 (http://bugs.mysql.com/31810))

   * *MySQL Cluster*: The `NDB' storage engine code was not safe for
     strict-alias optimization in `gcc' 4.2.1.  (Bug#31761
     (http://bugs.mysql.com/31761))

   * *MySQL Cluster*: It was possible in some cases for a node group to
     be `lost' due to missed local checkpoints following a system
     restart.  (Bug#31525 (http://bugs.mysql.com/31525))

   * *MySQL Cluster*: A query against a table with `TEXT' or `BLOB'
     columns that would return more than a certain amount of data
     failed with `Got error 4350 'Transaction already aborted' from
     NDBCLUSTER'.  (Bug#31482 (http://bugs.mysql.com/31482)) This
     regression was introduced by Bug#29102
     (http://bugs.mysql.com/29102)

   * *MySQL Cluster*: `NDB' tables having names containing
     non-alphanumeric characters (such as ` `$' ') were not discovered
     correctly.  (Bug#31470 (http://bugs.mysql.com/31470))

   * *MySQL Cluster*: A node failure during a local checkpoint could
     lead to a subsequent failure of the cluster during a system
     restart.  (Bug#31257 (http://bugs.mysql.com/31257))

   * *MySQL Cluster*: A cluster restart could sometimes fail due to an
     issue with table IDs.  (Bug#30975 (http://bugs.mysql.com/30975))

   * *MySQL Cluster*: When handling `BLOB' columns, the addition of
     read locks to the lock queue was not handled correctly.
     (Bug#30764 (http://bugs.mysql.com/30764))

   * *MySQL Cluster*: Discovery of `NDB' tables did not work correctly
     with `INFORMATION_SCHEMA'.  (Bug#30667
     (http://bugs.mysql.com/30667))

   * *MySQL Cluster*: A filesystem close operation could fail during a
     node or system restart.  (Bug#30646 (http://bugs.mysql.com/30646))

   * *MySQL Cluster*: Transaction timeouts were not handled well in some
     circumstances, leading to excessive number of transactions being
     aborted unnecessarily.  (Bug#30379 (http://bugs.mysql.com/30379))

   * *MySQL Cluster*: The cluster management client could not connect,
     and would hang instead. This issue affected Mac OS X 64-bit only.
     (Bug#30366 (http://bugs.mysql.com/30366))

   * *MySQL Cluster*: Attempting to restore a backup made on a cluster
     host using one endian to a machine using the other endian could
     cause the cluster to fail.  (Bug#29674
     (http://bugs.mysql.com/29674))

   * *MySQL Cluster*: Log event requests to `ndb_mgmd' could time out,
     causing it to fail.  (Bug#29621 (http://bugs.mysql.com/29621))

   * *MySQL Cluster*: In some cases, the cluster managment server
     logged entries multiple times following a restart of `mgmd'.
     (Bug#29565 (http://bugs.mysql.com/29565))

   * *MySQL Cluster*: `ndb_mgm `--help' ' did not display any
     information about the `-a' option.  (Bug#29509
     (http://bugs.mysql.com/29509))

   * *MySQL Cluster*: An interpreted program of sufficient size and
     complexity could cause all cluster data nodes to shut down due to
     buffer overruns.  (Bug#29390 (http://bugs.mysql.com/29390))

   * *MySQL Cluster*: `ndb_size.pl' failed on tables with `FLOAT'
     columns whose definitions included commas (for example,
     `FLOAT(6,2)').  (Bug#29228 (http://bugs.mysql.com/29228))

   * *MySQL Cluster*: The error message for `NDB' error code 275 (`Out
     of transaction records for complete phase') was missing.
     (Bug#29139 (http://bugs.mysql.com/29139))

   * *MySQL Cluster*: Reads on `BLOB' columns were not locked when they
     needed to be to guarantee consistency.  (Bug#29102
     (http://bugs.mysql.com/29102)) See also Bug#31482
     (http://bugs.mysql.com/31482)

   * *MySQL Cluster*: A query using joins between several large tables
     and requiring unique index lookups failed to complete, eventually
     returning `Uknown Error' after a very long period of time. This
     occurred due to inadequate handling of instances where the
     Transaction Coordinator ran out of `TransactionBufferMemory', when
     the cluster should have returned NDB error code 4012 (`Request
     ndbd time-out').  (Bug#28804 (http://bugs.mysql.com/28804))

   * *MySQL Cluster*: There was a short interval during the startup
     process prior to the beginning of heartbeat detection such that,
     were an API or management node to reboot or a network failure to
     occur, data nodes could not detect this, with the result that
     there could be a lingering connection.  (Bug#28445
     (http://bugs.mysql.com/28445))

   * *MySQL Cluster*: The description of the `--print' option provided
     in the output from `ndb_restore `--help' ' was incorrect.
     (Bug#27683 (http://bugs.mysql.com/27683))

   * *MySQL Cluster*: Restoring a backup made on a cluster host using
     one endian to a machine using the other endian failed for `BLOB'
     and `DATETIME' columns.  (Bug#27543 (http://bugs.mysql.com/27543),
     Bug#30024 (http://bugs.mysql.com/30024))

   * *MySQL Cluster*: An invalid subselect on an `NDB' table could
     cause `mysqld' to crash.  (Bug#27494 (http://bugs.mysql.com/27494))

   * *MySQL Cluster*: An attempt to perform a `SELECT ... FROM
     INFORMATION_SCHEMA.TABLES' whose result included information about
     `NDB' tables for which the user had no privileges crashed the
     MySQL Server on which the query was performed.  (Bug#26793
     (http://bugs.mysql.com/26793))

   * *MySQL Cluster*: Performing `DELETE' operations after a data node
     had been shut down could lead to inconsistent data following a
     restart of the node.  (Bug#26450 (http://bugs.mysql.com/26450))

   * *MySQL Cluster*: `UPDATE IGNORE' could sometimes fail on `NDB'
     tables due to the use of unitialized data when checking for
     duplicate keys to be ignored.  (Bug#25817
     (http://bugs.mysql.com/25817))

   * *MySQL Cluster*: The cluster log was formatted inconsistently and
     contained extraneous newline characters.  (Bug#25064
     (http://bugs.mysql.com/25064))

   * *MySQL Cluster*: A restart of the cluster failed when more than 1
     REDO phase was in use.  (Bug#22696 (http://bugs.mysql.com/22696))

   * *MySQL Cluster*: When inserting a row into an `NDB' table with a
     duplicate value for a non-primary unique key, the error issued
     would reference the wrong key.

     This improves on an initial fix for this issue made in MySQL
     5.1.13.  (Bug#21072 (http://bugs.mysql.com/21072))

   * *MySQL Cluster*: An insufficiently descriptive and potentially
     misleading Error 4006 (`Connect failure - out of connection
     objects...') was produced when either of the following two
     conditions occurred:

       1. There were no more transaction records in the transaction
          coordinator

       2. an `Ndb' object in the NDB API was initialized with
          insufficient parallellism

     Separate error messages are now generated for each of these two
     cases.  (Bug#11313 (http://bugs.mysql.com/11313))

   * *Partitioning*: *Replication*: Replication of partitioned tables
     using the `InnoDB' storage engine failed with `binlog-format=ROW'
     or `binlog-format=MIXED'.  (Bug#28430
     (http://bugs.mysql.com/28430))

   * *Partitioning*: It was possible to partition a table to which a
     foreign key referred.  (Bug#32948 (http://bugs.mysql.com/32948))

   * *Partitioning*: A query of the form `SELECT COL1 FROM TABLE GROUP
     BY (SELECT COL2 FROM TABLE LIMIT 1);' against a partitioned TABLE
     having a `SET' column crashed the server.  (Bug#32772
     (http://bugs.mysql.com/32772))

   * *Partitioning*: `SHOW CREATE TABLE' misreported the value of
     `AUTO_INCREMENT' for partitioned tables using either of the
     `InnoDB' or `ARCHIVE' storage engines.  (Bug#32247
     (http://bugs.mysql.com/32247))

   * *Partitioning*: Selecting from `INFORMATION_SCHEMA.PARTITIONS'
     while partition management statements (for example, `ALTER TABLE
     ... ADD PARTITION') were executing caused the server to crash.
     (Bug#32178 (http://bugs.mysql.com/32178))

   * *Partitioning*: An error in the internal function
     `mysql_unpack_partition()' led to a fatal error in subsequent
     calls to `open_table_from_share()'.  (Bug#32158
     (http://bugs.mysql.com/32158))

   * *Partitioning*: Repeated updates of a table that was partitioned by
     `KEY' on a `TIMESTAMP' column eventually crashed the server.
     (Bug#32067 (http://bugs.mysql.com/32067))

   * *Partitioning*: Changing the storage engine used by a table having
     subpartitions led to a server crash.  (Bug#31893
     (http://bugs.mysql.com/31893))

   * *Partitioning*: `ORDER BY ... DESC' did not always work correctly
     when selecting from partitioned tables.  (Bug#31890
     (http://bugs.mysql.com/31890)) See also Bug#31001
     (http://bugs.mysql.com/31001)

   * *Partitioning*: Selecting from a table partitioned by `KEY' on a
     `VARCHAR' column whose size was greater than 65530 caused the
     server to crash.  (Bug#31705 (http://bugs.mysql.com/31705))

   * *Partitioning*: `INSERT DELAYED' on a partitioned table crashed
     the server. The server now rejects the statement with an error.
     (Bug#31210 (http://bugs.mysql.com/31210))

   * *Partitioning*: Using `ALTER TABLE' to partition an existing table
     having an `AUTO_INCREMENT' column could crash the server.
     (Bug#30878 (http://bugs.mysql.com/30878)) This regression was
     introduced by Bug#27405 (http://bugs.mysql.com/27405)

   * *Partitioning*: `ALTER TABLE ... COALESCE PARTITION' on a table
     partitioned by `[LINEAR] HASH' or `[LINEAR] KEY' caused the server
     to crash.  (Bug#30822 (http://bugs.mysql.com/30822))

   * *Partitioning*: `LIKE' queries on tables partitioned by `KEY' and
     using third-party storage engines could return incomplete results.
     (Bug#30480 (http://bugs.mysql.com/30480)) See also Bug#29320
     (http://bugs.mysql.com/29320), Bug#29493
     (http://bugs.mysql.com/29493), Bug#30563
     (http://bugs.mysql.com/30563)

   * *Partitioning*: It was not possible to insert the greatest
     possible value for a given data type into a partitioned table. For
     example, consider a table defined as shown here:

          CREATE TABLE t (c BIGINT UNSIGNED)
              PARTITION BY RANGE(c) (
                PARTITION p0 VALUES LESS THAN MAXVALUE
              );

     The largest possible value for a `BIGINT UNSIGNED' column is
     18446744073709551615, but the statement `INSERT INTO t VALUES
     (18446744073709551615);' would fail, even though the same
     statement succeeded were `t' not a partitioned table.

     In other words, `MAXVALUE' was treated as being equal to the
     greatest possible value, rather than as a least upper bound.
     (Bug#29258 (http://bugs.mysql.com/29258))

   * *Replication*: When dropping a database containing a stored
     procedure while using row-cased replication, the delete of the
     stored procedure from the `mysql.proc' table was recorded in the
     binary log following the `DROP DATABASE' statement. To correct
     this issue, `DROP DATABASE' now uses statement-based replication.
     (Bug#32435 (http://bugs.mysql.com/32435))

   * *Replication*: It was possible for the name of the relay log file
     to exceed the amount of memory reserved for it, possibly leading
     to a crash of the server.  (Bug#31836
     (http://bugs.mysql.com/31836)) See also Bug#28597
     (http://bugs.mysql.com/28597)

   * *Replication*: Corruption of log events caused the server to crash
     on 64-bit Linux systems having 4 GB of memory or more.  (Bug#31793
     (http://bugs.mysql.com/31793))

   * *Replication*: Trying to replicate an update of a row that was
     missing on the slave led to a failure on the slave.  (Bug#31702
     (http://bugs.mysql.com/31702))

   * *Replication*: Table names were displayed as binary `garbage'
     characters in slave error messages. The issue was observed on
     64-bit Windows but may have effected other platforms.  (Bug#30854
     (http://bugs.mysql.com/30854))

   * *Replication*: One thread could read uninitialized memory from the
     stack of another thread. This issue was only known to occur in a
     `mysqld' process acting as both a master and a slave.  (Bug#30752
     (http://bugs.mysql.com/30752))

   * *Replication*: It was possible to set `SQL_SLAVE_SKIP_COUNTER'
     such that the slave would jump into the middle of a transaction.
     This fix improves on one made for this bug in MySQL 5.1.20; the
     previous fix insured that the slave could not be made to jump into
     the middle of an event group, but the slave failed to recognize
     that `BEGIN', `COMMIT', and `ROLLBACK' statements could begin or
     end an event group.  (Bug#28618 (http://bugs.mysql.com/28618)) See
     also Bug#12691 (http://bugs.mysql.com/12691)

   * *Replication*: Due a previous change in how the default name and
     location of the binlog file were determined, replication failed
     following some upgrades.  (Bug#28597
     (http://bugs.mysql.com/28597), Bug#28603
     (http://bugs.mysql.com/28603)) See also Bug#31836
     (http://bugs.mysql.com/31836)

     This regression was introduced by Bug#20166
     (http://bugs.mysql.com/20166)

   * *Replication*: Stored procedures having `BIT' parameters were not
     replicated correctly.  (Bug#26199 (http://bugs.mysql.com/26199))

   * *Replication*: Issuing `SHOW SLAVE STATUS' as `mysqld' was
     shutting down could cause a crash.  (Bug#26000
     (http://bugs.mysql.com/26000))

   * *Replication*: If a temporary error occured inside an event group
     on an event that was not the first event of the group, the slave
     could get caught in an endless loop because the retry counter was
     reset whenever an event was executed successfully.  (Bug#24860
     (http://bugs.mysql.com/24860)) See also Bug#12691
     (http://bugs.mysql.com/12691), Bug#23171
     (http://bugs.mysql.com/23171)

   * *Replication*: An `UPDATE' statement using a stored function that
     modified a non-transactional table was not logged if it failed.
     This caused the copy of the non-transactional table on the master
     have a row that the copy on the slave did not.  (Bug#23333
     (http://bugs.mysql.com/23333)) See also Bug#12713
     (http://bugs.mysql.com/12713)

   * *Replication*: A replication slave sometimes failed to reconnect
     because it was unable to run `SHOW SLAVE HOSTS'. It was not
     necessary to run this statement on slaves (since the master should
     track connection IDs), and the execution of this statement by
     slaves was removed.  (Bug#21132 (http://bugs.mysql.com/21132)) See
     also Bug#13963 (http://bugs.mysql.com/13963), Bug#21869
     (http://bugs.mysql.com/21869)

   * *Replication*: A replication slave sometimes stopped for changes
     that were idempotent (that is, such changes should have been
     considered `safe'), even though it should have simply noted that
     the change was already done, and continued operation.  (Bug#19958
     (http://bugs.mysql.com/19958))

   * *Cluster Replication*: A replication slave could return `garbage'
     data that was not in recognizable row format due to a problem with
     the internal `all_set()' method.  (Bug#33375
     (http://bugs.mysql.com/33375))

   * *Cluster Replication*: Memory was mistakenly freed for `NdbBlob'
     objects when adding an index while replicating the cluster, which
     could cause `mysqld' to crash.  (Bug#33142
     (http://bugs.mysql.com/33142)) See also Bug#18106
     (http://bugs.mysql.com/18106)

   * *Cluster Replication*: Under certain conditions, the slave stopped
     processing relay logs. This resulted in the logs never being
     cleared and the slave eventually running out of disk space.
     (Bug#31958 (http://bugs.mysql.com/31958))

   * *Cluster Replication*: A node failure during replication could
     lead to buckets out of order; now active subscribers are checked
     for, rather than empty buckets.  (Bug#31701
     (http://bugs.mysql.com/31701))

   * *Cluster Replication*: Replicating `NDB' tables with extra
     `VARCHAR' columns on the master caused the slave to fail.
     (Bug#31646 (http://bugs.mysql.com/31646)) See also Bug#29549
     (http://bugs.mysql.com/29549)

   * *Cluster Replication*: When the master `mysqld' crashed or was
     restarted, no `LOST_EVENTS' entry was made in the binlog.
     (Bug#31484 (http://bugs.mysql.com/31484)) See also Bug#21494
     (http://bugs.mysql.com/21494)

   * *Cluster Replication*: Incorrect handling of `INSERT' plus
     `DELETE' operations with regard to local checkpoints caused data
     node failures in multi-master replication setups.  (Bug#30914
     (http://bugs.mysql.com/30914))

   * *Cluster Replication*: An issue with the `mysql.ndb_apply_status'
     table could cause `NDB' schema autodiscovery to fail in certain
     rare circumstances.  (Bug#20872 (http://bugs.mysql.com/20872))

   * *Cluster API*: A call to `CHECK_TIMEDOUT_RET()' in `mgmapi.cpp'
     should have been a call to `DBUG_CHECK_TIMEDOUT_RET()'.
     (Bug#30681 (http://bugs.mysql.com/30681))

   * *Cluster API*: An `Ndb' object in the NDB API was initialized with
     insufficient parallellism

   * *API*: When the language option was not set correctly, API programs
     calling *Note `mysql_server_init()': mysql-server-init.  crashed.
     This issue was observed only on Windows platforms.  (Bug#31868
     (http://bugs.mysql.com/31868))

   * Corrected a typecast involving `bool' on Mac OS X 10.5 (Leopard),
     which evaluated differently from earlier Mac OS X versions.
     (Bug#38217 (http://bugs.mysql.com/38217))

   * Use of uninitialized memory for `filesort' in a subquery caused a
     server crash.  (Bug#33675 (http://bugs.mysql.com/33675))

   * `CREATE TABLE ... SELECT' created tables that for date columns
     used the obsolete `Field_date' type instead of `Field_newdate'.
     (Bug#33256 (http://bugs.mysql.com/33256))

   * Some valid `SELECT' statements could not be used as views due to
     incorrect column reference resolution.  (Bug#33133
     (http://bugs.mysql.com/33133))

   * The fix for Bug#11230 (http://bugs.mysql.com/11230) and Bug#26215
     (http://bugs.mysql.com/26215) introduced a significant
     input-parsing slowdown for the `mysql' client.  This has been
     corrected.  (Bug#33057 (http://bugs.mysql.com/33057))

   * The correct data type for a `NULL' column resulting from a `UNION'
     could be determined incorrectly in some cases: 1) Not correctly
     inferred as `NULL' depending on the number of selects; 2) Not
     inferred correctly as `NULL' if one select used a subquery.
     (Bug#32848 (http://bugs.mysql.com/32848))

   * For queries containing `GROUP_CONCAT(DISTINCT COL_LIST ORDER BY
     COL_LIST)', there was a limitation that the `DISTINCT' columns had
     to be the same as `ORDER BY' columns. Incorrect results could be
     returned if this was not true.  (Bug#32798
     (http://bugs.mysql.com/32798))

   * `SHOW EVENTS' and selecting from the `INFORMATION_SCHEMA.EVENTS'
     table failed if the current database was `INFORMATION_SCHEMA'.
     (Bug#32775 (http://bugs.mysql.com/32775))

   * Use of the `cp932' character set with `CAST()' in an `ORDER BY'
     clause could cause a server crash.  (Bug#32726
     (http://bugs.mysql.com/32726))

   * A subquery using an `IS NULL' check of a column defined as `NOT
     NULL' in a table used in the `FROM' clause of the outer query
     produced an invalid result.  (Bug#32694
     (http://bugs.mysql.com/32694))

   * `mysqld_safe' looked for error messages in the wrong location.
     (Bug#32679 (http://bugs.mysql.com/32679))

   * Specifying a non-existent column for an `INSERT DELAYED' statement
     caused a server crash rather than producing an error.  (Bug#32676
     (http://bugs.mysql.com/32676))

   * An issue with the `NO_ENGINE_SUBSTITUTION' `sql_mode' database can
     cause the creation of stored routines to fail. If you are having
     problems with creating stored routines while using this `sql_mode'
     value, remove this value from your `sql_mode' setting.  (Bug#32633
     (http://bugs.mysql.com/32633))

   * Use of `CLIENT_MULTI_QUERIES' caused `libmysqld' to crash.
     (Bug#32624 (http://bugs.mysql.com/32624))

   * The `INTERVAL()' function incorrectly handled `NULL' values in the
     value list.  (Bug#32560 (http://bugs.mysql.com/32560))

   * Use of a `NULL'-returning `GROUP BY' expression in conjunction
     with `WITH ROLLUP' could cause a server crash.  (Bug#32558
     (http://bugs.mysql.com/32558)) See also Bug#31095
     (http://bugs.mysql.com/31095)

   * `ORDER BY UpdateXML(...)' caused the server to crash in queries
     where `UpdateXML()' returned `NULL'.  (Bug#32557
     (http://bugs.mysql.com/32557))

   * A `SELECT ... GROUP BY BIT_COLUMN' query failed with an assertion
     if the length of the `BIT' column used for the `GROUP BY' was not
     an integer multiple of 8.  (Bug#32556
     (http://bugs.mysql.com/32556))

   * Using `SELECT INTO OUTFILE' with 8-bit `ENCLOSED BY' characters
     led to corrupted data when the data was reloaded using LOAD DATA
     INFILE. This was because `SELECT INTO OUTFILE' failed to escape
     the 8-bit characters.  (Bug#32533 (http://bugs.mysql.com/32533))

   * For `FLUSH TABLES WITH READ LOCK', the server failed to properly
     detect write-locked tables when running with low-priority updates,
     resulting in a crash or deadlock.  (Bug#32528
     (http://bugs.mysql.com/32528))

   * The rules for valid column names were being applied differently
     for base tables and views.  (Bug#32496
     (http://bugs.mysql.com/32496))

   * A query of the form `SELECT @USER_VARIABLE := CONSTANT AS ALIAS
     FROM TABLE GROUP BY ALIAS WITH ROLLUP' crashed the server.
     (Bug#32482 (http://bugs.mysql.com/32482))

   * Sending several `KILL QUERY' statements to target a connection
     running `SELECT SLEEP()' could freeze the server.  (Bug#32436
     (http://bugs.mysql.com/32436))

   * `ssl-cipher' values in option files were not being read by
     `libmysqlclient'.  (Bug#32429 (http://bugs.mysql.com/32429))

   * Repeated execution of a query containing a `CASE' expression and
     numerous `AND' and `OR' relations could crash the server. The root
     cause of the issue was determined to be that the internal
     `SEL_ARG' structure was not properly initialized when created.
     (Bug#32403 (http://bugs.mysql.com/32403))

   * Referencing within a subquery an alias used in the `SELECT' list
     of the outer query was incorrectly permitted.  (Bug#32400
     (http://bugs.mysql.com/32400))

   * If a global read lock acquired with `FLUSH TABLES WITH READ LOCK'
     was in effect, executing `ALTER TABLE' could cause a server crash.
     (Bug#32395 (http://bugs.mysql.com/32395))

   * An `ORDER BY' query on a view created using a `FEDERATED' table as
     a base table caused the server to crash.  (Bug#32374
     (http://bugs.mysql.com/32374))

   * The `mysqldump' utility did not print enough version information
     about itself at the top of its output. The output now shows the
     same information as `mysqldump' invoked with the `-V' option,
     namely the `mysqldump' version number, the MySQL server version,
     and the distribution.  (Bug#32350 (http://bugs.mysql.com/32350))

   * Comparison of a `BIGINT NOT NULL' column with a constant
     arithmetic expression that evaluated to NULL mistakenly caused the
     error `Column '...' cannot be null' (error 1048).  (Bug#32335
     (http://bugs.mysql.com/32335))

   * Assigning a 65,536-byte string to a `TEXT' column (which can hold
     a maximum of 65,535 bytes) resulted in truncation without a
     warning. Now a truncation warning is generated.  (Bug#32282
     (http://bugs.mysql.com/32282))

   * The `LAST_DAY()' function returns a `DATE' value, but internally
     the value did not have the time fields zeroed and calculations
     involving the value could return incorrect results.  (Bug#32270
     (http://bugs.mysql.com/32270))

   * `MIN()' and `MAX()' could return incorrect results when an index
     was present if a loose index scan was used.  (Bug#32268
     (http://bugs.mysql.com/32268))

   * Some uses of user variables in a query could result in a server
     crash.  (Bug#32260 (http://bugs.mysql.com/32260))

   * Memory corruption could occur due to large index map in `Range
     checked for each record' status reported by `EXPLAIN SELECT'. The
     problem was based in an incorrectly calculated length of the
     buffer used to store a hexadecimal representation of an index map,
     which could result in buffer overrun and stack corruption under
     some circumstances.  (Bug#32241 (http://bugs.mysql.com/32241))

   * Various test program cleanups were made: 1) `mytest' and
     `libmysqltest' were removed. 2) `bug25714' displays an error
     message when invoked with incorrect arguments or the `--help'
     option. 3) `mysql_client_test' exits cleanly with a proper error
     status.  (Bug#32221 (http://bugs.mysql.com/32221))

   * The default grant tables on Windows contained information for host
     `production.mysql.com', which should not be there.  (Bug#32219
     (http://bugs.mysql.com/32219))

   * Under certain conditions, the presence of a `GROUP BY' clause
     could cause an `ORDER BY' clause to be ignored.  (Bug#32202
     (http://bugs.mysql.com/32202))

   * For comparisons of the form DATE_COL OP DATETIME_CONST (where OP is
     `=', `<', `>', `<=', or `>='), the comparison is done using
     `DATETIME' values, per the fix for Bug#27590
     (http://bugs.mysql.com/27590). However that fix caused any index on
     DATE_COL not to be used and compromised performance. Now the index
     is used again.  (Bug#32198 (http://bugs.mysql.com/32198))

   * `DATETIME' arguments specified in numeric form were treated by
     `DATE_ADD()' as `DATE' values.  (Bug#32180
     (http://bugs.mysql.com/32180))

   * Killing a statement could lead to a race condition in the server.
     (Bug#32148 (http://bugs.mysql.com/32148))

   * `InnoDB' does not support `SPATIAL' indexes, but could crash when
     asked to handle one. Now an error is returned.  (Bug#32125
     (http://bugs.mysql.com/32125))

   * The server crashed on optimizations involving a join of `INT' and
     `MEDIUMINT' columns and a system variable in the `WHERE' clause.
     (Bug#32103 (http://bugs.mysql.com/32103))

   * `mysql-test-run.pl' used the `--user' option when starting
     `mysqld', which produces warnings if the current user is not
     `root'. Now `--user' is added only for `root'.  (Bug#32078
     (http://bugs.mysql.com/32078))

   * `mysqlslap' was missing from the MySQL 5.1.22 Linux RPM packages.
     (Bug#32077 (http://bugs.mysql.com/32077))

   * With `lower_case_table_names' set, `CREATE TABLE LIKE' was treated
     differently by `libmysqld' than by the non-embedded server.
     (Bug#32063 (http://bugs.mysql.com/32063))

   * Within a subquery, `UNION' was handled differently than at the top
     level, which could result in incorrect results or a server crash.
     (Bug#32036 (http://bugs.mysql.com/32036), Bug#32051
     (http://bugs.mysql.com/32051))

   * On 64-bit platforms, assignments of values to enumeration-valued
     storage engine-specific system variables were not validated and
     could result in unexpected values.  (Bug#32034
     (http://bugs.mysql.com/32034))

   * A `DELETE' statement with a subquery in the `WHERE' clause would
     sometimes ignore an error during subquery evaluation and proceed
     with the delete operation.  (Bug#32030
     (http://bugs.mysql.com/32030))

   * Using dates in the range `'0000-00-01'' to `'0000-00-99'' range in
     the `WHERE' clause could result in an incorrect result set. (These
     dates are not in the supported range for `DATE', but different
     results for a given query could occur depending on position of
     records containing the dates within a table.)  (Bug#32021
     (http://bugs.mysql.com/32021))

   * User-defined functions are not loaded if the server is started
     with the `--skip-grant-tables' option, but the server did not
     properly handle this case and issued an `Out of memory' error
     message instead.  (Bug#32020 (http://bugs.mysql.com/32020))

   * If a user-defined function was used in a `SELECT' statement, and
     an error occurred during UDF initialization, the error did not
     terminate execution of the `SELECT', but rather was converted to a
     warning.  (Bug#32007 (http://bugs.mysql.com/32007))

   * `HOUR()', `MINUTE()', and `SECOND()' could return non-zero values
     for `DATE' arguments.  (Bug#31990 (http://bugs.mysql.com/31990))

   * Changing the SQL mode to cause dates with `zero' parts to be
     considered invalid (such as `'1000-00-00'') could result in
     indexed and non-indexed searches returning different results for a
     column that contained such dates.  (Bug#31928
     (http://bugs.mysql.com/31928))

   * The server used unnecessarily large amounts of memory when user
     variables were used as an argument to `CONCAT()' or `CONCAT_WS()'.
     (Bug#31898 (http://bugs.mysql.com/31898))

   * In debug builds, testing the result of an `IN' subquery against
     `NULL' caused an assertion failure.  (Bug#31884
     (http://bugs.mysql.com/31884))

   * `mysql-test-run.pl' sometimes set up test scenarios in which the
     same port number was passed to multiple servers, causing one of
     them to be unable to start.  (Bug#31880
     (http://bugs.mysql.com/31880))

   * `SHOW CREATE TRIGGER' caused a server crash.  (Bug#31866
     (http://bugs.mysql.com/31866))

   * The server crashed after insertion of a negative value into an
     `AUTO_INCREMENT' column of an `InnoDB' table.  (Bug#31860
     (http://bugs.mysql.com/31860))

   * For `libmysqld' applications, handling of *Note
     `mysql_change_user()': mysql-change-user. calls left some pointers
     improperly updated, leading to server crashes.  (Bug#31850
     (http://bugs.mysql.com/31850))

   * Using `ORDER BY' led to the wrong result when using the `ARCHIVE'
     on a table with a `BLOB' when the table cache was full. The table
     could also be reported as crashed after the query had completed,
     even though the table data was intact.  (Bug#31833
     (http://bugs.mysql.com/31833))

   * Comparison results for `BETWEEN' were different from those for
     operators like `<' and `>' for `DATETIME'-like values with
     trailing extra characters such as `'2007-10-01 00:00:00 GMT-6''.
     `BETWEEN' treated the values as `DATETIME', whereas the other
     operators performed a binary-string comparison. Now they all
     uniformly use a `DATETIME' comparison, but generate warnings for
     values with trailing garbage.  (Bug#31800
     (http://bugs.mysql.com/31800))

   * Name resolution for correlated subqueries and `HAVING' clauses
     failed to distinguish which of two was being performed when there
     was a reference to an outer aliased field. This could result in
     error messages about a `HAVING' clause for queries that had no such
     clause.  (Bug#31797 (http://bugs.mysql.com/31797))

   * The server could crash during `filesort' for `ORDER BY' based on
     expressions with `INET_NTOA()' or `OCT()' if those functions
     returned `NULL'.  (Bug#31758 (http://bugs.mysql.com/31758))

   * For tables with certain definitions, `UPDATE' statements could
     fail to find the correct record to update and report an error when
     the record did in fact exist.  (Bug#31747
     (http://bugs.mysql.com/31747))

   * For a fatal error during a filesort in `find_all_keys()', the
     error was returned without the necessary handler uninitialization,
     causing an assertion failure.  (Bug#31742
     (http://bugs.mysql.com/31742))

   * `mysqlslap' failed to commit after the final record load.
     (Bug#31704 (http://bugs.mysql.com/31704))

   * The examined-rows count was not incremented for `const' queries.
     (Bug#31700 (http://bugs.mysql.com/31700))

   * The server crashed if a thread was killed while locking the
     `general_log' table at the beginning of statement processing.
     (Bug#31692 (http://bugs.mysql.com/31692))

   * The *Note `mysql_change_user()': mysql-change-user. C API function
     was subject to buffer overflow.  (Bug#31669
     (http://bugs.mysql.com/31669))

   * For `SELECT ... INTO OUTFILE', if the `ENCLOSED BY' string is
     empty and the `FIELDS TERMINATED BY' string started with a special
     character (one of `n', `t', `r', `b', `0', `Z', or `N'), every
     occurrence of the character within field values would be
     duplicated.  (Bug#31663 (http://bugs.mysql.com/31663))

   * `SHOW COLUMNS' and `DESCRIBE' displayed `null' as the column type
     for a view with no valid definer. This caused `mysqldump' to
     produce a non-reloadable dump file for the view.  (Bug#31662
     (http://bugs.mysql.com/31662))

   * The `mysqlbug' script did not include the correct values of
     `CFLAGS' and `CXXFLAGS' that were used to configure the
     distribution.  (Bug#31644 (http://bugs.mysql.com/31644))

   * Queries that include a comparison of an `INFORMATION_SCHEMA' table
     column to `NULL' caused a server crash.  (Bug#31633
     (http://bugs.mysql.com/31633))

   * `EXPLAIN EXTENDED' for `SELECT' from `INFORMATION_SCHEMA' tables
     caused an assertion failure.  (Bug#31630
     (http://bugs.mysql.com/31630))

   * `ucs2' does not work as a client character set, but attempts to
     use it as such were not rejected. Now `character_set_client'
     cannot be set to `ucs2'. This also affects statements such as `SET
     NAMES' and `SET CHARACTER SET'.  (Bug#31615
     (http://bugs.mysql.com/31615))

   * A buffer used when setting variables was not dimensioned to
     accommodate the trailing `'\0'' byte, so a single-byte buffer
     overrun was possible.  (Bug#31588 (http://bugs.mysql.com/31588))

   * `HAVING' could treat lettercase of table aliases incorrectly if
     `lower_case_table_names' was enabled.  (Bug#31562
     (http://bugs.mysql.com/31562))

   * Spurious duplicate-key errors could occur for multiple-row inserts
     into an `InnoDB' table that activate a trigger.  (Bug#31540
     (http://bugs.mysql.com/31540))

   * Using `ALTER EVENT' to rename a disabled event caused it to become
     enabled.  (Bug#31539 (http://bugs.mysql.com/31539))

   * The fix for Bug#24989 (http://bugs.mysql.com/24989) introduced a
     problem such that a `NULL' thread handler could be used during a
     rollback operation. This problem is unlikely to be seen in
     practice.  (Bug#31517 (http://bugs.mysql.com/31517))

   * The length of the result from `IFNULL()' could be calculated
     incorrectly because the sign of the result was not taken into
     account.  (Bug#31471 (http://bugs.mysql.com/31471))

   * Queries that used the `ref' access method or index-based subquery
     execution over indexes that have `DECIMAL' columns could fail with
     an error `Column COL_NAME cannot be null'.  (Bug#31450
     (http://bugs.mysql.com/31450))

   * `InnoDB' now tracks locking and use of tables by MySQL only after
     a table has been successfully locked on behalf of a transaction.
     Previously, the locked flag was set and the table in-use counter
     was updated before checking whether the lock on the table
     succeeded. A subsequent failure in obtaining a lock on the table
     led to an inconsistent state as the table was neither locked nor
     in use.  (Bug#31444 (http://bugs.mysql.com/31444))

   * `SELECT 1 REGEX NULL' caused an assertion failure for debug
     servers.  (Bug#31440 (http://bugs.mysql.com/31440))

   * The `UpdateXML()' function did not check for the validity of all
     its arguments; in some cases, this could lead to a crash of the
     server.  (Bug#31438 (http://bugs.mysql.com/31438))

   * The *Note `mysql_change_user()': mysql-change-user. C API function
     caused advisory locks (obtained with `GET_LOCK()') to malfunction.
     (Bug#31418 (http://bugs.mysql.com/31418))

   * NDB libraries and include files were missing from some binary
     `tar' file distributions.  (Bug#31414
     (http://bugs.mysql.com/31414))

   * Executing `RENAME' while tables were open for use with `HANDLER'
     statements could cause a server crash.  (Bug#31409
     (http://bugs.mysql.com/31409))

   * `mysql-test-run.pl' tried to create files in a directory where it
     could not be expected to have write permission. `mysqltest' created
     `.reject' files in a directory other than the one where test
     results go.  (Bug#31398 (http://bugs.mysql.com/31398))

   * For a table that had been opened with `HANDLER' and marked for
     reopening after being closed with `FLUSH TABLES', `DROP TABLE' did
     not properly discard the handler.  (Bug#31397
     (http://bugs.mysql.com/31397))

   * Automatically allocated memory for string options associated with
     a plugin was not freed if the plugin did not get installed.
     (Bug#31382 (http://bugs.mysql.com/31382))

   * `INFORMATION_SCHEMA.TABLES' was returning incorrect information.
     (Bug#31381 (http://bugs.mysql.com/31381))

   * `DROP USER' caused an increase in memory usage.  (Bug#31347
     (http://bugs.mysql.com/31347))

   * `mysql_install_db' failed if the default storage engine was `NDB'.
     Now it explicitly uses `MyISAM' as the storage engine when running
     `mysqld --bootstrap'.  (Bug#31315 (http://bugs.mysql.com/31315))

   * For `InnoDB' tables with `READ COMMITTED' isolation level, `UPDATE'
     statements skipped rows locked by another transaction, rather than
     waiting for the locks to be released.  (Bug#31310
     (http://bugs.mysql.com/31310))

   * For an almost-full `MyISAM' table, an insert that failed could
     leave the table in a corrupt state.  (Bug#31305
     (http://bugs.mysql.com/31305))

   * `myisamchk --unpack' could corrupt a table that when unpacked has
     static (fixed-length) row format.  (Bug#31277
     (http://bugs.mysql.com/31277))

   * `CONVERT(VAL, DATETIME)' would fail on invalid input, but
     processing was not aborted for the `WHERE' clause, leading to a
     server crash.  (Bug#31253 (http://bugs.mysql.com/31253))

   * Allocation of an insufficiently large group-by buffer following
     creation of a temporary table could lead to a server crash.
     (Bug#31249 (http://bugs.mysql.com/31249))

   * Use of `DECIMAL(N, N) ZEROFILL' in `GROUP_CONCAT()' could cause a
     server crash.  (Bug#31227 (http://bugs.mysql.com/31227))

   * When a `TIMESTAMP' with a non-zero time part was converted to a
     `DATE' value, no warning was generated. This caused index lookups
     to assume that this is a valid conversion and was returning rows
     that match a comparison between a `TIMESTAMP' value and a `DATE'
     keypart. Now a warning is generated so that `TIMESTAMP' with a
     non-zero time part will not match `DATE' values.  (Bug#31221
     (http://bugs.mysql.com/31221))

   * Server variables could not be set to their current values on Linux
     platforms.  (Bug#31177 (http://bugs.mysql.com/31177)) See also
     Bug#6958 (http://bugs.mysql.com/6958)

   * WIth small values of `myisam_sort_buffer_size', `REPAIR TABLE' for
     `MyISAM' tables could cause a server crash.  (Bug#31174
     (http://bugs.mysql.com/31174))

   * Use of the `@@hostname' system variable in inserts in
     `mysql_system_tables_data.sql' did not replicate. The workaround
     is to select its value into a user variable (which does replicate)
     and insert that.  (Bug#31167 (http://bugs.mysql.com/31167))

   * If `MAKETIME()' returned `NULL' when used in an `ORDER BY' that
     was evaluated using `filesort', a server crash could result.
     (Bug#31160 (http://bugs.mysql.com/31160))

   * Data in `BLOB' or `GEOMETRY' columns could be cropped when
     performing a `UNION' query.  (Bug#31158
     (http://bugs.mysql.com/31158))

   * `LAST_INSERT_ID()' execution could be handled improperly in
     subqueries.  (Bug#31157 (http://bugs.mysql.com/31157))

   * An assertion designed to detect a bug in the `ROLLUP'
     implementation would incorrectly be triggered when used in a
     subquery context with non-cacheable statements.  (Bug#31156
     (http://bugs.mysql.com/31156))

   * Selecting spatial types in a `UNION' could cause a server crash.
     (Bug#31155 (http://bugs.mysql.com/31155))

   * Use of `GROUP_CONCAT(DISTINCT BIT_COLUMN)' caused an assertion
     failure.  (Bug#31154 (http://bugs.mysql.com/31154))

   * The server crashed in the parser when running out of memory.
     Memory handling in the parser has been improved to gracefully
     return an error when out-of-memory conditions occur in the parser.
     (Bug#31153 (http://bugs.mysql.com/31153))

   * MySQL declares a `UNIQUE' key as a `PRIMARY' key if it doesn't have
     `NULL' columns and is not a partial key, and the `PRIMARY' key
     must alway be the first key.  However, in some cases, a non-first
     key could be reported as `PRIMARY', leading to an assert failure by
     `InnoDB'. This is fixed by correcting the key sort order.
     (Bug#31137 (http://bugs.mysql.com/31137))

   * `mysqldump' failed to handle databases containing a ``-''
     character in the name.  (Bug#31113 (http://bugs.mysql.com/31113))

   * Starting the server using `--read-only' and with the Event
     Scheduler enabled caused it to crash.

     *Note*:

     This issue occurred only when the server had been built with
     certain nonstandard combinations of `configure' options.

     (Bug#31111 (http://bugs.mysql.com/31111))

   * `GROUP BY NULL WITH ROLLUP' could cause a server crash.
     (Bug#31095 (http://bugs.mysql.com/31095)) See also Bug#32558
     (http://bugs.mysql.com/32558)

   * A rule to prefer `filesort' over an indexed `ORDER BY' when
     accessing all rows of a table was being used even if a `LIMIT'
     clause was present.  (Bug#31094 (http://bugs.mysql.com/31094))

   * `REGEXP' operations could cause a server crash for character sets
     such as `ucs2'. Now the arguments are converted to `utf8' if
     possible, to allow correct results to be produced if the resulting
     strings contain only 8-bit characters.  (Bug#31081
     (http://bugs.mysql.com/31081))

   * Expressions of the form `WHERE COL NOT IN (COL, ...)', where the
     same column was named both times, could cause a server crash in the
     optimizer.  (Bug#31075 (http://bugs.mysql.com/31075))

   * Internal conversion routines could fail for several multi-byte
     character sets (`big5', `cp932', `euckr', `gb2312', `sjis') for
     empty strings or during evaluation of `SOUNDS LIKE'.  (Bug#31069
     (http://bugs.mysql.com/31069), Bug#31070
     (http://bugs.mysql.com/31070))

   * Many nested subqueries in a single query could led to excessive
     memory consumption and possibly a crash of the server.  (Bug#31048
     (http://bugs.mysql.com/31048))

   * Using `ORDER BY' with `ARCHIVE' tables caused a server crash.
     (Bug#31036 (http://bugs.mysql.com/31036))

   * A server crash could occur when a non-`DETERMINISTIC' stored
     function was used in a `GROUP BY' clause.  (Bug#31035
     (http://bugs.mysql.com/31035))

   * The `MOD()' function and the `%' operator crashed the server for a
     divisor less than 1 with a very long fractional part.  (Bug#31019
     (http://bugs.mysql.com/31019))

   * Transactions were committed prematurely when `LOCK TABLE' and `SET
     AUTOCOMMIT=OFF' were used together.  (Bug#30996
     (http://bugs.mysql.com/30996))

   * On Windows, the `pthread_mutex_trylock()' implementation was
     incorrect.  (Bug#30992 (http://bugs.mysql.com/30992))

   * A character set introducer followed by a hexadecimal or bit-value
     literal did not check its argument and could return an ill-formed
     result for invalid input.  (Bug#30986
     (http://bugs.mysql.com/30986))

   * `CHAR(STR USING CHARSET)' did not check its argument and could
     return an ill-formed result for invalid input.  (Bug#30982
     (http://bugs.mysql.com/30982))

   * The result from `CHAR(STR USING ucs2') did not add a leading 0x00
     byte for input strings with an odd number of bytes.  (Bug#30981
     (http://bugs.mysql.com/30981))

   * The `GeomFromText()' function could cause a server crash if the
     first argument was `NULL' or the empty string.  (Bug#30955
     (http://bugs.mysql.com/30955))

   * `MAKEDATE()' incorrectly moved year values in the 100-200 range
     into the 1970-2069 range. (This is legitimate for 00-99, but
     three-digit years should be used unchanged.)  (Bug#30951
     (http://bugs.mysql.com/30951))

   * When invoked with constant arguments, `STR_TO_DATE()' could use a
     cached value for the format string and return incorrect results.
     (Bug#30942 (http://bugs.mysql.com/30942))

   * `GROUP_CONCAT()' returned `','' rather than an empty string when
     the argument column contained only empty strings.  (Bug#30897
     (http://bugs.mysql.com/30897))

   * For `MEMORY' tables, lookups for `NULL' values in `BTREE' indexes
     could return incorrect results.  (Bug#30885
     (http://bugs.mysql.com/30885))

   * A server crash could occur if a stored function that contained a
     `DROP TEMPORARY TABLE' statement was invoked by a `CREATE
     TEMPORARY TABLE' statement that created a table of the same name.
     (Bug#30882 (http://bugs.mysql.com/30882))

   * Calling `NAME_CONST()' with non-constant arguments triggered an
     assertion failure.  Non-constant arguments are now disallowed.
     (Bug#30832 (http://bugs.mysql.com/30832))

   * For a spatial column with a regular (non-`SPATIAL') index, queries
     failed if the optimizer tried to use the index.  (Bug#30825
     (http://bugs.mysql.com/30825))

   * Values for the `--tc-heuristic-recover' option incorrectly were
     treated as values for the `--myisam-stats-method' option.
     (Bug#30821 (http://bugs.mysql.com/30821))

   * `INFORMATION_SCHEMA.SCHEMATA' was returning incorrect information.
     (Bug#30795 (http://bugs.mysql.com/30795))

   * The optimizer incorrectly optimized conditions out of the `WHERE'
     clause in some queries involving subqueries and indexed columns.
     (Bug#30788 (http://bugs.mysql.com/30788))

   * Improper calculation of `CASE' expression results could lead to
     value truncation.  (Bug#30782 (http://bugs.mysql.com/30782))

   * On Windows, the `pthread_mutex_trylock()' implementation was
     incorrect. One symptom was that invalidating the query cache could
     cause a server crash.  (Bug#30768 (http://bugs.mysql.com/30768))

   * A multiple-table `UPDATE' involving transactional and
     non-transactional tables caused an assertion failure.  (Bug#30763
     (http://bugs.mysql.com/30763))

   * User-supplied names foreign key names might not be set to the
     right key, leading to foreign keys with no name.  (Bug#30747
     (http://bugs.mysql.com/30747))

   * Under some circumstances, `CREATE TABLE ...  SELECT' could crash
     the server or incorrectly report that the table row size was too
     large.  (Bug#30736 (http://bugs.mysql.com/30736))

   * Using the `MIN()' or `MAX()' function to select one part of a
     multi-part key could cause a crash when the function result was
     `NULL'.  (Bug#30715 (http://bugs.mysql.com/30715))

   * The embedded server did not properly check column-level privileges.
     (Bug#30710 (http://bugs.mysql.com/30710))

   * `INFORMATION_SCHEMA.VIEWS.VIEW_DEFINITION' was incorrect for views
     that were defined to select from other `INFORMATION_SCHEMA' tables.
     (Bug#30689 (http://bugs.mysql.com/30689))

   * Issuing an `ALTER SERVER' statement to update the settings for a
     `FEDERATED' server would cause the `mysqld' to crash.  (Bug#30671
     (http://bugs.mysql.com/30671))

   * The optimizer could ignore `ORDER BY' in cases when the result set
     is ordered by `filesort', resulting in rows being returned in
     incorrect order.  (Bug#30666 (http://bugs.mysql.com/30666))

   * A different execution plan was displayed for `EXPLAIN' than would
     actually have been used for the `SELECT' because the test of sort
     keys for `ORDER BY' did not consider keys mentioned in `IGNORE
     KEYS FOR ORDER BY'.  (Bug#30665 (http://bugs.mysql.com/30665))

   * The `thread_handling' system variable was treated as having a
     `SESSION' value and as being settable at runtime. Now it has only a
     `GLOBAL' read-only value.  (Bug#30651
     (http://bugs.mysql.com/30651))

   * On Windows, `LIMIT' arguments greater than 2^32 did not work
     correctly.  (Bug#30639 (http://bugs.mysql.com/30639))

   * `MyISAM' tables could not exceed 4294967295 (2^32 - 1) rows on
     Windows.  (Bug#30638 (http://bugs.mysql.com/30638))

   * A failed `HANDLER ... READ' operation could leave the table in a
     locked state.  (Bug#30632 (http://bugs.mysql.com/30632))

   * `mysql-test-run.pl' could not run `mysqld' with `root' privileges.
     (Bug#30630 (http://bugs.mysql.com/30630))

   * The `mysqld_safe' script contained a syntax error.  (Bug#30624
     (http://bugs.mysql.com/30624))

   * The optimization that uses a unique index to remove `GROUP BY' did
     not ensure that the index was actually used, thus violating the
     `ORDER BY' that is implied by `GROUP BY'.  (Bug#30596
     (http://bugs.mysql.com/30596))

   * `SHOW STATUS LIKE 'Ssl_cipher_list'' from a MySQL client connected
     via SSL returned an empty string rather than a list of available
     ciphers.  (Bug#30593 (http://bugs.mysql.com/30593))

   * For `MEMORY' tables, `DELETE' statements that remove rows based on
     an index read could fail to remove all matching rows.  (Bug#30590
     (http://bugs.mysql.com/30590))

   * Using `GROUP BY' on an expression of the form `TIMESTAMP_COL DIV
     NUMBER' caused a server crash due to incorrect calculation of
     number of decimals.  (Bug#30587 (http://bugs.mysql.com/30587))

   * Executing a `SELECT COUNT(*)' query on an `InnoDB' table
     partitioned by `KEY' that used a `DOUBLE' column as the
     partitioning key caused the server to crash.  (Bug#30583
     (http://bugs.mysql.com/30583))

   * The options available to the `CHECK TABLE' statement were also
     allowed in `OPTIMIZE TABLE' and `ANALYZE TABLE' statements, but
     caused corruption during their execution. These options were never
     supported for the these statements, and an error is now raised if
     you try to apply these options to these statements.  (Bug#30495
     (http://bugs.mysql.com/30495))

   * A self-referencing trigger on a partitioned table caused the
     server to crash instead of failing with an error.  (Bug#30484
     (http://bugs.mysql.com/30484))

   * The *Note `mysql_change_user()': mysql-change-user. C API function
     did not correctly reset the character set variables to the values
     they had just after initially connecting.  (Bug#30472
     (http://bugs.mysql.com/30472))

   * When expanding a `*' in a `USING' or `NATURAL' join, the check for
     table access for both tables in the join was done using only the
     grant information of the first table.  (Bug#30468
     (http://bugs.mysql.com/30468))

   * When casting a string value to an integer, cases where the input
     string contained a decimal point and was long enough to overrun
     the `unsigned long long' type were not handled correctly. The
     position of the decimal point was not taken into account which
     resulted in miscalculated numbers and incorrect truncation to
     appropriate SQL data type limits.  (Bug#30453
     (http://bugs.mysql.com/30453))

   * Versions of `mysqldump' from MySQL 4.1 or higher tried to use
     `START TRANSACTION WITH CONSISTENT SNAPSHOT' if the
     `--single-transaction' and `--master-data' options were given,
     even with servers older than 4.1 that do not support consistent
     snapshots.  (Bug#30444 (http://bugs.mysql.com/30444))

   * With `libmysqld', use of prepared statements and the query cache
     at the same time caused problems.  (Bug#30430
     (http://bugs.mysql.com/30430))

   * Issuing a `DELETE' statement having both an `ORDER BY' clause and a
     `LIMIT' clause could cause `mysqld' to crash.  (Bug#30385
     (http://bugs.mysql.com/30385))

   * For `CREATE ... SELECT ... FROM', where the resulting table
     contained indexes, adding `SQL_BUFFER_RESULT' to the `SELECT' part
     caused index corruption in the table.  (Bug#30384
     (http://bugs.mysql.com/30384))

   * The `Last_query_cost' status variable value can be computed
     accurately only for simple `flat' queries, not complex queries
     such as those with subqueries or `UNION'. However, the value was
     not consistently being set to 0 for complex queries.  (Bug#30377
     (http://bugs.mysql.com/30377))

   * The optimizer made incorrect assumptions about the value of the
     `is_member' value for user-defined functions, sometimes resulting
     in incorrect ordering of UDF results.  (Bug#30355
     (http://bugs.mysql.com/30355))

   * Queries that had a `GROUP BY' clause and selected `COUNT(DISTINCT
     BIT_COLUMN)' returned incorrect results.  (Bug#30324
     (http://bugs.mysql.com/30324))

   * Some valid `euc-kr' characters having the second byte in the
     ranges `[0x41..0x5A]' and `[0x61..0x7A]' were rejected.
     (Bug#30315 (http://bugs.mysql.com/30315))

   * When loading a dynamic plugin on FreeBSD, the plugin would fail to
     load. This was due to a build error where the required symbols
     would be not exported correctly.  (Bug#30296
     (http://bugs.mysql.com/30296))

   * Simultaneous `ALTER TABLE' statements for `BLACKHOLE' tables
     caused 100% CPU use due to locking problems.  (Bug#30294
     (http://bugs.mysql.com/30294))

   * Setting certain values on a table using a spatial index could
     cause the server to crash.  (Bug#30286
     (http://bugs.mysql.com/30286))

   * Tables with a `GEOMETRY' column could be marked as corrupt if you
     added a non-`SPATIAL' index on a `GEOMETRY' column.  (Bug#30284
     (http://bugs.mysql.com/30284))

   * Flushing a merge table between the time it was opened and its
     child table were actually attached caused the server to crash.
     (Bug#30273 (http://bugs.mysql.com/30273)) This regression was
     introduced by Bug#26379 (http://bugs.mysql.com/26379)

   * The query cache does not support retrieval of statements for which
     column level access control applies, but the server was still
     caching such statements, thus wasting memory.  (Bug#30269
     (http://bugs.mysql.com/30269))

   * Using `DISTINCT' or `GROUP BY' on a `BIT' column in a `SELECT'
     statement caused the column to be cast internally as an integer,
     with incorrect results being returned from the query.  (Bug#30245
     (http://bugs.mysql.com/30245))

   * `GROUP BY' on `BIT' columns produced incorrect results.
     (Bug#30219 (http://bugs.mysql.com/30219))

   * Short-format `mysql' commands embedded within `/*! ... */'
     comments were parsed incorrectly by `mysql', which discarded the
     rest of the comment including the terminating `*/' characters. The
     result was a malformed (unclosed) comment. Now `mysql' does not
     discard the `*/' characters.  (Bug#30164
     (http://bugs.mysql.com/30164))

   * If the server crashed during an `ALTER TABLE' statement, leaving a
     temporary file in the database directory, a subsequent `DROP
     DATABASE' statement failed due to the presence of the temporary
     file.  (Bug#30152 (http://bugs.mysql.com/30152))

   * When `mysqldump' wrote `DROP DATABASE' statements within
     version-specific comments, it included the terminating semicolon
     in the wrong place, causing following statements to fail when the
     dump file was reloaded.  (Bug#30126 (http://bugs.mysql.com/30126))

   * It was not possible for client applications to distinguish between
     auto-set and auto-updated `TIMESTAMP' column values.

     To rectify this problem, a new `ON_UPDATE_NOW_FLAG' flag is set by
     Field_timestamp constructors whenever a column should be set to
     `NOW' on `UPDATE', and the `get_schema_column_record()' function
     now reports whether a timestamp column is set to `NOW' on
     `UPDATE'. In addition, such columns now display `on update
     CURRENT_TIMESTAMP' in the `Extra' column in the output from `SHOW
     COLUMNS'.  (Bug#30081 (http://bugs.mysql.com/30081))

   * Some `INFORMATION_SCHEMA' tables are intended for internal use,
     but could be accessed by using `SHOW' statements.  (Bug#30079
     (http://bugs.mysql.com/30079))

   * On some 64-bit systems, inserting the largest negative value into
     a `BIGINT' column resulted in incorrect data.  (Bug#30069
     (http://bugs.mysql.com/30069))

   * `mysqlslap' did not properly handle multiple result sets from
     stored procedures.  (Bug#29985 (http://bugs.mysql.com/29985))

   * Specifying the `--without-geometry' option for `configure' caused
     server compilation to fail.  (Bug#29972
     (http://bugs.mysql.com/29972))

   * Statements within stored procedures ignored the value of the
     `low_priority_updates' system variable.  (Bug#29963
     (http://bugs.mysql.com/29963)) See also Bug#26162
     (http://bugs.mysql.com/26162)

   * With auto-reconnect enabled, row fetching for a prepared statement
     could crash after reconnect occurred because loss of the statement
     handler was not accounted for.  (Bug#29948
     (http://bugs.mysql.com/29948))

   * `mysqldump `--skip-events --all-databases' ' dumped data from the
     `mysqld.event' table, and when restoring from this dump, events
     were created in spite of the `--skip-events' option.  (Bug#29938
     (http://bugs.mysql.com/29938))

   * When `mysqlslap' was given a query to execute from a file via a
     `--query=FILE_NAME ' option, it executed the query one too many
     times.  (Bug#29803 (http://bugs.mysql.com/29803))

   * `configure' did not find `nss' on some Linux platforms.
     (Bug#29658 (http://bugs.mysql.com/29658))

   * It was possible when creating a partitioned table using `CREATE
     TABLE ... SELECT' to refer in the `PARTITION BY' clause to columns
     in the table being selected from, which could cause the server to
     crash. An example of such a statement is:

          CREATE TABLE t1 (b INT)
          PARTITION BY RANGE(t2.b) (
              PARTITION p1 VALUES LESS THAN (10),
              PARTITION p2 VALUES LESS THAN (20)
          )   SELECT * FROM t2;

     The fix is to disallow references in `PARTITION BY' clauses to
     columns not in the table being created.  (Bug#29444
     (http://bugs.mysql.com/29444))

   * If a view used a function in its `SELECT' statement, the columns
     from the view were not inserted into the
     `INFORMATION_SCHEMA.COLUMNS' table.  (Bug#29408
     (http://bugs.mysql.com/29408))

   * The `mysql' client program now ignores Unicode byte order mark
     (BOM) characters at the beginning of input files. Previously, it
     read them and sent them to the server, resulting in a syntax error.

     Presence of a BOM does not cause `mysql' to change its default
     character set. To do that, invoke `mysql' with an option such as
     `--default-character-set=utf8'.  (Bug#29323
     (http://bugs.mysql.com/29323))

   * For transactional tables, an error during a multiple-table
     `DELETE' statement did not roll back the statement.  (Bug#29136
     (http://bugs.mysql.com/29136))

   * The `log' and `log_slow_queries' system variables were displayed
     by `SHOW VARIABLES' but could not be accessed in expressions as
     `@@log' and `@@log_slow_queries'. Also, attempting to set them
     with `SET' produced an incorrect `Unknown system variable'
     message. Now these variables are treated as synonyms for
     `general_log' and `slow_query_log', which means that they can be
     accessed in expressions and their values can be changed with `SET'.
     (Bug#29131 (http://bugs.mysql.com/29131))

   * Denormalized double-precision numbers cannot be handled properly
     by old MIPS pocessors. For IRIX, this is now handled by enabling a
     mode to use a software workaround.  (Bug#29085
     (http://bugs.mysql.com/29085))

   * `SHOW VARIABLES' did not display the `relay_log',
     `relay_log_index', or `relay_log_info_file' system variables.
     (Bug#28893 (http://bugs.mysql.com/28893))

   * When doing a `DELETE' on table that involved a `JOIN' with
     `MyISAM' or `MERGE' tables and the `JOIN' referred to the same
     table, the operation could fail reporting `ERROR 1030 (HY000): Got
     error 134 from storage engine'. This was because scans on the
     table contents would change because of rows that had already been
     deleted.  (Bug#28837 (http://bugs.mysql.com/28837))

   * Killing an SSL connection on platforms where MySQL is compiled
     with `-DSIGNAL_WITH_VIO_CLOSE' (Windows, Mac OS X, and some
     others) could crash the server.  (Bug#28812
     (http://bugs.mysql.com/28812))

   * `SHOW VARIABLES' did not correctly display the value of the
     `thread_handling' system variable.  (Bug#28785
     (http://bugs.mysql.com/28785))

   * On Windows, `mysql_upgrade' created temporary files in `C:\' and
     did not clean them up.  (Bug#28774 (http://bugs.mysql.com/28774))

   * Index hints specified in view definitions were ignored when using
     the view to select from the base table.  (Bug#28702
     (http://bugs.mysql.com/28702))

   * Views do not have indexes, so index hints do not apply. Use of
     index hints when selecting from a view is now disallowed.
     (Bug#28701 (http://bugs.mysql.com/28701))

   * After changing the SQL mode to a restrictive value that would make
     already-inserted dates in a column be considered invalid, searches
     returned different results depending on whether the column was
     indexed.  (Bug#28687 (http://bugs.mysql.com/28687))

   * When running the MySQL Instance Configuration Wizard, a race
     condition could exist that would fail to connect to a newly
     configured instance. This was because `mysqld' had not completed
     the startup process before the next stage of the installation
     process.  (Bug#28628 (http://bugs.mysql.com/28628))

   * A `SELECT' in one connection could be blocked by `INSERT ... ON
     DUPLICATE KEY UPDATE' in another connection even when
     `low_priority_updates' is set.  (Bug#28587
     (http://bugs.mysql.com/28587))

   * `mysql_upgrade' could run binaries dynamically linked against
     incorrect versions of shared libraries.  (Bug#28560
     (http://bugs.mysql.com/28560))

   * The result from `CHAR()' was incorrectly assumed in some contexts
     to return a single-byte result.  (Bug#28550
     (http://bugs.mysql.com/28550))

   * `mysqldump' reversed the event name and program name in one of its
     error messages.  (Bug#28535 (http://bugs.mysql.com/28535))

   * If a `LIMIT' clause was present, the server could fail to consider
     indexes that could be used for `ORDER BY' or `GROUP BY'.
     (Bug#28404 (http://bugs.mysql.com/28404))

   * The parser confused user-defined function (UDF) and stored
     function creation for `CREATE FUNCTION' and required that there be
     a default database when creating UDFs, although there is no such
     requirement.  (Bug#28318 (http://bugs.mysql.com/28318), Bug#29816
     (http://bugs.mysql.com/29816))

   * Fast-mutex locking was not thread-safe and optimization-safe on
     some platforms, which could cause program failures such as
     out-of-memory errors.  (Bug#28284 (http://bugs.mysql.com/28284))

   * The result of a comparison between `VARBINARY' and `BINARY'
     columns differed depending on whether the `VARBINARY' column was
     indexed.  (Bug#28076 (http://bugs.mysql.com/28076))

   * The metadata in some `MYSQL_FIELD' members could be incorrect when
     a temporary table was used to evaluate a query.  (Bug#27990
     (http://bugs.mysql.com/27990))

   * Partition pruning was not used for queries having `<=' or `>='
     conditions in the `WHERE' clause on a table using `TO_DAYS()' in
     the partitioning expression.  (Bug#27927
     (http://bugs.mysql.com/27927))

   * `mysqlbinlog' produced incorrectly formatted `DATETIME' and
     `TIMESTAMP' values.  (Bug#27894 (http://bugs.mysql.com/27894))

   * Failure to log to the `general_log' or `slow_log' log tables were
     not logged to the error log at all or were logged incorrectly.
     (Bug#27858 (http://bugs.mysql.com/27858))

   * An `ORDER BY' at the end of a `UNION' affected individual `SELECT'
     statements rather than the overall query result.  (Bug#27848
     (http://bugs.mysql.com/27848))

   * `comp_err' created files with permissions such that they might be
     inaccessible during `make install' operations.  (Bug#27789
     (http://bugs.mysql.com/27789))

   * `SHOW COLUMNS' returned `NULL' instead of the empty string for the
     `Default' value of columns that had no default specified.
     (Bug#27747 (http://bugs.mysql.com/27747))

   * It was possible to create a view having a column whose name
     consisted of an empty string or space characters only.  (Bug#27695
     (http://bugs.mysql.com/27695)) See also Bug#31202
     (http://bugs.mysql.com/31202)

   * With recent versions of DBD::mysql, `mysqlhotcopy' generated table
     names that were doubly qualified with the database name.
     (Bug#27694 (http://bugs.mysql.com/27694))

   * The anonymous accounts were not being created during MySQL
     installation.  (Bug#27692 (http://bugs.mysql.com/27692))

   * Some `SHOW' statements and `INFORMATION_SCHEMA' queries could
     expose information not allowed by the user's access privileges.
     (Bug#27629 (http://bugs.mysql.com/27629))

   * `ALTER TABLE TBL_NAME ROW_FORMAT=FORMAT_TYPE' did not cause the
     table to be rebuilt.  (Bug#27610 (http://bugs.mysql.com/27610))

   * A race condition between killing a statement and the thread
     executing the statement could lead to a situation such that the
     binary log contained an event indicating that the statement was
     killed, whereas the statement actually executed to completion.
     (Bug#27571 (http://bugs.mysql.com/27571))

   * Some character mappings in the `ascii.xml' file were incorrect.
     (Bug#27562 (http://bugs.mysql.com/27562))

   * Some queries using the `NAME_CONST()' function failed to return
     either a result or an error to the client, causing it to hang.
     This was due to the fact that there was no check to insure that
     both arguments to this function were constant expressions.
     (Bug#27545 (http://bugs.mysql.com/27545), Bug#32559
     (http://bugs.mysql.com/32559))

   * With the `read_only' system variable enabled, `CREATE DATABASE'
     and `DROP DATABASE' were allowed to users who did not have the
     `SUPER' privilege.  (Bug#27440 (http://bugs.mysql.com/27440))

   * For an event with an `ON COMPLETION' value of `PRESERVE', an
     `ALTER EVENT' statement that specified no `ON COMPLETION' option
     caused the value to become `NOT PRESERVE'.  (Bug#27407
     (http://bugs.mysql.com/27407))

   * MySQL failed to generate or retrieve an `AUTO_INCREMENT' primary
     key for `InnoDB' tables with user-defined partitioning.
     (Bug#27405 (http://bugs.mysql.com/27405))

   * Changes to the `sql_mode' system variable were not tracked by
     `INSERT DELAYED'.  (Bug#27358 (http://bugs.mysql.com/27358))

   * A `SELECT' with more than 31 nested dependent subqueries returned
     an incorrect result.  (Bug#27352 (http://bugs.mysql.com/27352))

   * The `ExtractValue()' and `UpdateXML()' functions performed
     extremely slowly for large amounts of XML data (greater than 64
     KB). These functions now execute approximately 2000 times faster
     than previously.  (Bug#27287 (http://bugs.mysql.com/27287))

   * On Windows, writes to the debug log were using `freopen()' instead
     of `fflush()', resulting in slower performance.  (Bug#27099
     (http://bugs.mysql.com/27099))

   * For a table that used different full-text parsers for different
     `FULLTEXT' indexes, `SHOW CREATE TABLE' displayed the first parser
     name for all of them.  (Bug#27040 (http://bugs.mysql.com/27040))

   * `STR_TO_DATE()' displayed an error message that referred to
     `STR_TO_TIME()'.  (Bug#27014 (http://bugs.mysql.com/27014))

   * The *Note `mysql_insert_id()': mysql-insert-id. C API function
     sometimes returned different results for `libmysqld' and
     `libmysqlclient'.  (Bug#26921 (http://bugs.mysql.com/26921))

   * Symbolic links on Windows could fail to work.  (Bug#26811
     (http://bugs.mysql.com/26811))

   * `mysqld' sometimes miscalculated the number of digits required
     when storing a floating-point number in a `CHAR' column. This
     caused the value to be truncated, or (when using a debug build)
     caused the server to crash.  (Bug#26788
     (http://bugs.mysql.com/26788)) See also Bug#12860
     (http://bugs.mysql.com/12860)

   * `LOAD DATA INFILE' ran very slowly when reading large files into
     partitioned tables.  (Bug#26527 (http://bugs.mysql.com/26527))

   * It makes no sense to attempt to use `ALTER TABLE ...  ORDER BY' to
     order an `InnoDB' table if there is a user-defined clustered
     index, because rows are always ordered by the clustered index.
     Such attempts now are ignored and produce a warning.

     Also, in some cases, `InnoDB' incorrectly used a secondary index
     when the clustered index would produce a faster scan. `EXPLAIN'
     output now indicates use of the clustered index (for tables that
     have one) as lines with a `type' value of `index', a `key' value
     of `PRIMARY', and without `Using index' in the `Extra' value.
     (Bug#26447 (http://bugs.mysql.com/26447)) See also Bug#35850
     (http://bugs.mysql.com/35850)

   * Using `HANDLER' to open a table having a storage engine not
     supported by `HANDLER' properly returned an error, but also
     improperly prevented the table from being dropped by other
     connections.  (Bug#25856 (http://bugs.mysql.com/25856))

   * For a prepared statement STMT, changing the default database
     following `PREPARE STMT' but before `EXECUTE STMT' caused STMT to
     be recorded incorrectly in the binary log.  (Bug#25843
     (http://bugs.mysql.com/25843))

   * `CREATE TABLE LIKE' did not work when the source table was an
     `INFORMATION_SCHEMA' table.  (Bug#25629
     (http://bugs.mysql.com/25629))

   * Threads that were calculating the estimated number of records for
     a range scan did not respond to the `KILL' statement. That is, if
     a `range' join type is possible (even if not selected by the
     optimizer as a join type of choice and thus not shown by
     `EXPLAIN'), the query in the `statistics' state (shown by the
     `SHOW PROCESSLIST') did not respond to the `KILL' statement.
     (Bug#25421 (http://bugs.mysql.com/25421))

   * For `InnoDB' tables, `CREATE TABLE a AS SELECT * FROM A' would
     fail.  (Bug#25164 (http://bugs.mysql.com/25164))

   * For `mysql --show-warnings', warnings were in some cases not
     displayed.  (Bug#25146 (http://bugs.mysql.com/25146))

   * The `returns' column of the `mysql.proc' table was `CHAR(64)',
     which is not long enough to store long data types such as `ENUM'
     types. The column has been changed to `LONGBLOB' and a warning is
     generated if truncation occurs when storing a row into the `proc'
     table.  (Bug#24923 (http://bugs.mysql.com/24923))

   * If the expected precision of an arithmetic expression exceeded the
     maximum precision supported by MySQL, the precision of the result
     was reduced by an unpredictable or arbitrary amount, rather than
     to the maximum precision. In some cases, exceeding the maximum
     supported precision could also lead to a crash of the server.
     (Bug#24907 (http://bugs.mysql.com/24907))

   * For Vista installs, `MySQLInstanceConfig.exe' did not add the
     default MySQL port to the firewall exceptions.  It now provides a
     checkbox that enables the user a choice of whether to do this.
     (Bug#24853 (http://bugs.mysql.com/24853))

   * A `CREATE TRIGGER' statement could cause a deadlock or server
     crash if it referred to a table for which a table lock had been
     acquired with `LOCK TABLES'.  (Bug#23713
     (http://bugs.mysql.com/23713))

   * For storage engines that do not redefine
     `handler::index_next_same()' and are capable of indexes,
     statements that include a `WHERE' clause might select incorrect
     data.  (Bug#22351 (http://bugs.mysql.com/22351))

   * The parser treated the `INTERVAL()' function incorrectly, leading
     to situations where syntax errors could result depending on which
     side of an arithmetic operator the function appeared.  (Bug#22312
     (http://bugs.mysql.com/22312))

   * Entries in the general query log were truncated at 1000 characters.
     (Bug#21557 (http://bugs.mysql.com/21557))

   * A memory leak occurred when `CREATE TEMPORARY TABLE ..  SELECT'
     was invoked from a stored function that in turn was called from
     `CREATE TABLE ... SELECT'.  (Bug#21136
     (http://bugs.mysql.com/21136))

   * It was possible to execute `CREATE TABLE t1 ... SELECT ... FROM
     t2' with the `CREATE' privilege for `t1' and `SELECT' privilege
     for `t2', even in the absence of the `INSERT' privilege for `t1'.
     (Bug#20901 (http://bugs.mysql.com/20901))

   * Worked around an `icc' problem with an incorrect machine
     instruction being generated in the context of software
     pre-fetching after a subroutine got in-lined.  (Upgrading to `icc'
     10.0.026 makes the workaround unnecessary.)  (Bug#20803
     (http://bugs.mysql.com/20803))

   * If a column selected by a view referred to a stored function, the
     data type reported for the column in `INFORMATION_SCHEMA.COLUMNS'
     could be incorrect.  (Bug#20550 (http://bugs.mysql.com/20550))

   * The *Note `mysql_change_user()': mysql-change-user. C API function
     changed the value of the `SQL_BIG_SELECTS' session variable.
     (Bug#20023 (http://bugs.mysql.com/20023))

   * Hostnames sometimes were treated as case sensitive in
     account-management statements (`CREATE USER', `GRANT', `REVOKE',
     and so forth).  (Bug#19828 (http://bugs.mysql.com/19828))

   * Issuing an SQL `KILL' of the active connection caused an error on
     Mac OS X.  (Bug#19723 (http://bugs.mysql.com/19723))

   * The `readline' library has been updated to version 5.2. This
     addresses issues in the `mysql' client where history and editing
     within the client would fail to work as expected.  (Bug#18431
     (http://bugs.mysql.com/18431))

   * The `-lmtmalloc' library was removed from the output of
     `mysql_config' on Solaris, as it caused problems when building
     `DBD::mysql' (and possibly other applications) on that platform
     that tried to use `dlopen()' to access the client library.
     (Bug#18322 (http://bugs.mysql.com/18322))

   * `MySQLInstanceConfig.exe' failed to grant certain privileges to
     the `'root'@'%'' account.  (Bug#17303
     (http://bugs.mysql.com/17303))

   * The `Aborted_clients' status variable was incremented twice if a
     client exited without calling *Note `mysql_close()': mysql-close.
     (Bug#16918 (http://bugs.mysql.com/16918))

   * Use of `GRANT' statements with grant tables from an old version of
     MySQL could cause a server crash.  (Bug#16470
     (http://bugs.mysql.com/16470))

   * Clients were ignoring the TCP/IP port number specified as the
     default port via the -with-tcp-port configuration option.
     (Bug#15327 (http://bugs.mysql.com/15327))

   * Parameters of type `DATETIME' or `DATE' in stored procedures were
     silently converted to `VARBINARY'.  (Bug#13675
     (http://bugs.mysql.com/13675))

   * Zero-padding of exponent values was not the same across platforms.
     (Bug#12860 (http://bugs.mysql.com/12860))

   * Values of types `REAL ZEROFILL', `DOUBLE ZEROFILL', `FLOAT
     ZEROFILL', were not zero-filled when converted to a character
     representation in the C prepared statement API.  (Bug#11589
     (http://bugs.mysql.com/11589))

   * `mysql' stripped comments from statements sent to the server. Now
     the `--comments' or `--skip-comments' option can be used to control
     whether to retain or strip comments. The default is
     `--skip-comments'.  (Bug#11230 (http://bugs.mysql.com/11230),
     Bug#26215 (http://bugs.mysql.com/26215))

   * Several buffer-size system variables were either being handled
     incorrectly for large values (for settings larger than 4GB, they
     were truncated to values less than 4GB without a warning), or were
     limited unnecessarily to 4GB even on 64-bit systems. The following
     changes were made:

        * For `key_buffer_size', values larger than 4GB are allowed on
          64-bit platforms.

        * For `join_buffer_size', `sort_buffer_size', and
          `myisam_sort_buffer_size', values larger than 4GB are allowed
          on 64-bit platforms (except Windows, for which large values
          are truncated to 4GB with a warning).

     In addition, settings for `read_buffer_size' and
     `read_rnd_buffer_size' are limited to 2GB on all platforms. Larger
     values are truncated to 2GB with a warning.  (Bug#5731
     (http://bugs.mysql.com/5731), Bug#29419
     (http://bugs.mysql.com/29419), Bug#29446
     (http://bugs.mysql.com/29446))

   * Executing `DISABLE KEYS' and `ENABLE KEYS' on a non-empty table
     would cause the size of the index file for the table to grow
     considerable. This was because the `DISABLE KEYS' operation would
     only mark the existing index, without deleting the index blocks.
     The `ENABLE KEYS' operation would re-create the index, adding new
     blocks, while the previous index blocks would remain. Existing
     indexes are now dropped and recreated when the `ENABLE KEYS'
     statement is executed.  (Bug#4692 (http://bugs.mysql.com/4692))

   * Grant table checks failed in `libmysqld'.

   * There were no more transaction records in the transaction
     coordinator

   * Replicating from a master table to a slave table where the size of
     a `CHAR' or `VARCHAR' column was a different size would cause
     `mysqld' to crash. For more information on replicating with
     different column definitions, see *Note
     replication-features-differing-tables::.


File: manual.info,  Node: news-5-1-22,  Next: news-5-1-21,  Prev: news-5-1-23,  Up: news-5-1-x

C.1.8 Changes in MySQL 5.1.22 (24 September 2007: Release Candidate)
--------------------------------------------------------------------

Functionality added or changed:

   * There is a new `innodb_autoinc_lock_mode' system variable to
     configure the locking behavior that `InnoDB' uses for generating
     auto-increment values. The default behavior now is slightly
     different from before, which involves a minor incompatibility for
     multiple-row inserts that specify an explicit value for the
     auto-increment column in some but not all rows. See *Note
     innodb-auto-increment-handling::.

Bugs fixed:

   * *MySQL Cluster*: Backups of `TIMESTAMP' columns made with
     `ndb_restore' on a MySQL Cluster using data nodes hosts of one
     endian could not be used to restore the cluster's data to data
     node hosts of the other endian.  (Bug#30134
     (http://bugs.mysql.com/30134))

   * *MySQL Cluster*: (Replication): Multi-master replication setups
     did not handle `--log-slave-updates' correctly.  (Bug#30017
     (http://bugs.mysql.com/30017))

   * Row-based replication from a pre-5.1.22 MySQL Server to a MySQL
     5.1.22 was unstable due to an uninitialized variable.  (Bug#31076
     (http://bugs.mysql.com/31076))

   * For an `InnoDB' table if a `SELECT' was ordered by the primary key
     and also had a `WHERE field = value' clause on a different field
     that was indexed, a `DESC' order instruction would be ignored.
     (Bug#31001 (http://bugs.mysql.com/31001))

   * `mysql_install_db' could fail to find its message file.
     (Bug#30678 (http://bugs.mysql.com/30678))

   * Memory corruption occurred for some queries with a top-level `OR'
     operation in the `WHERE' condition if they contained equality
     predicates and other sargable predicates in disjunctive parts of
     the condition.  (Bug#30396 (http://bugs.mysql.com/30396))

   * `CONNECTION_ID()' always returned 0 for the embedded server
     (`libmysqld').  (Bug#30389 (http://bugs.mysql.com/30389))

   * The server created temporary tables for filesort operations in the
     working directory, not in the directory specified by the `tmpdir'
     system variable.  (Bug#30287 (http://bugs.mysql.com/30287))

   * Using `KILL QUERY' or `KILL CONNECTION' to kill a `SELECT'
     statement caused a server crash if the query cache was enabled.
     (Bug#30201 (http://bugs.mysql.com/30201))

   * `mysqldump' from the MySQL 5.1.21 distribution could not be used
     to create a dump from a MySQL 5.1.20 or older server.  (Bug#30123
     (http://bugs.mysql.com/30123))

   * Under some circumstances, a UDF initialization function could be
     passed incorrect argument lengths.  (Bug#29804
     (http://bugs.mysql.com/29804))

   * Operations that used the time zone replicated the time zone only
     for successful operations, but did not replicate the time zone for
     errors that need to know it.  (Bug#29536
     (http://bugs.mysql.com/29536))

   * When using a combination of `HANDLER... READ' and `DELETE' on a
     table, MySQL continued to open new copies of the table every time,
     leading to an exhaustion of file descriptors.  (Bug#29474
     (http://bugs.mysql.com/29474)) This regression was introduced by
     Bug#21587 (http://bugs.mysql.com/21587)

   * The *Note `mysql_list_fields()': mysql-list-fields. C API function
     incorrectly set `MYSQL_FIELD::decimals' for some view columns.
     (Bug#29306 (http://bugs.mysql.com/29306))

   * Tables using the `InnoDB' storage engine incremented
     `AUTO_INCREMENT' values incorrectly with `ON DUPLICATE KEY UPDATE'.
     (Bug#28781 (http://bugs.mysql.com/28781))

   * Non-range queries of the form `SELECT ... FROM ... WHERE
     KEYPART1=CONSTANT, ..., KEYPARTN=CONSTANT ORDER BY ... FOR UPDATE'
     sometimes were unnecessarily blocked waiting for a lock if another
     transaction was using `SELECT ... FOR UPDATE' on the same table.
     (Bug#28570 (http://bugs.mysql.com/28570))

   * On Windows, symbols for yaSSL and taocrypt were missing from
     `mysqlclient.lib', resulting in unresolved symbol errors for
     clients linked against that library.  (Bug#27861
     (http://bugs.mysql.com/27861))

   * Read lock requests that were blocked by a pending write lock
     request were not allowed to proceed if the statement requesting
     the write lock was killed.  (Bug#21281
     (http://bugs.mysql.com/21281))


File: manual.info,  Node: news-5-1-21,  Next: news-5-1-20,  Prev: news-5-1-22,  Up: news-5-1-x

C.1.9 Changes in MySQL 5.1.21 (16 August 2007)
----------------------------------------------

This is a new Beta development release, fixing recently discovered bugs.

*Note*:

This Beta release, as any other pre-production release, should not be
installed on _production_ level systems or systems with critical data.
It is good practice to back up your data before installing any new
version of software.  Although MySQL has worked very hard to ensure a
high level of quality, protect your data by making a backup as you
would for any software beta release. Please refer to our bug database at
`http://bugs.mysql.com/' for more details about the individual bugs
fixed in this version.

*Note*:

Subsequent to release, it was discovered that on some platforms,
`mysql_install_db' could fail to find its message file, resulting in
error messages of the following form:

     shell> mysql_install_db
     Installing MySQL system tables...
     070830  9:33:24 [ERROR] Can't find messagefile 'PATH/share/english/errmsg.sys'
     070830  9:33:24 [ERROR] Aborting

To deal with this problem, specify a `--language' option to specify the
proper pathname to the language file directory. For example:

     shell> mysql_install_db --language=/path/to/share/english/

This problem is corrected in MySQL 5.1.22.

This section documents all changes and bug fixes that have been applied
since the last official MySQL release. If you would like to receive
more fine-grained and personalized _update alerts_ about fixes that are
relevant to the version and features you use, please consider
subscribing to _MySQL Enterprise_ (a commercial MySQL offering). For
more details please see `http://www.mysql.com/products/enterprise'.

Functionality added or changed:

   * *Incompatible Change*: In MySQL 5.1.6, when log tables were
     implemented, the default log destination for the general query and
     slow query log was `TABLE'. This default has been changed to
     `FILE', which is compatible with MySQL 5.0, but incompatible with
     earlier releases of MySQL 5.1 from 5.1.6 to 5.1.20. If you are
     upgrading from MySQL 5.0 to this release, no logging option
     changes should be necessary. However, if you are upgrading from
     5.1.6 through 5.1.20 to this release and were using `TABLE'
     logging, use the `--log-output=TABLE' option explicitly to
     preserve your server's table-logging behavior.

     In MySQL 5.1.x, this bug was addressed twice because it turned out
     that the default was set in two places, only one of which was
     fixed the first time.  (Bug#29993 (http://bugs.mysql.com/29993))

   * *Incompatible Change*: The `innodb_log_arch_dir' system variable
     (which has been deprecated since MySQL 5.0.24) has been removed
     and should no longer be used.

   * *Incompatible Change*: On Windows only, the `mysqld-nt' has been
     removed from this release and all future releases. The `mysqld'
     server now includes named-pipe support as standard, and you do not
     have to use the `mysqld-nt' version to enable named-pipe support.

   * *Important Change*: The default `mysqld_safe' logging behavior now
     is `--skip-syslog' rather than `--syslog', which is compatible
     with the default behavior of writing an error log file for
     releases prior to 5.1.20.

   * Several programs now accept `--debug-check' and `--debug-info'
     options: `mysql', `mysqladmin', `mysqlbinlog', `mysqlcheck',
     `mysqldump', `mysqlimport', `mysqlshow', `mysqlslap', `mysqltest',
     `mysql_upgrade'. (Note: `mysql', `mysqladmin', `mysqlcheck',
     `mysqldump', `mysqlimport', `mysqlshow', and `mysqltest' already
     accepted `--debug-info'.) `--debug-check' prints debugging
     information at program exit.  `--debug-info' is similar but also
     prints memory and CPU usage statistics. This patch also corrects a
     problem for `mysql' that `--debug-info' did not display statistics
     at exit time.  (Bug#30127 (http://bugs.mysql.com/30127))

   * The `--syslog' option that was introduced in 5.1.20 for
     `mysqld_safe' (to send error output to `syslog') did not work
     correctly: Error output was buffered and not logged immediately.
     This has been corrected. In addition, some feature changes were
     made:

        * *Important*:

          The default `mysqld_safe' logging behavior now is
          `--skip-syslog' rather than `--syslog', which is compatible
          with the default behavior of writing an error log file for
          releases prior to 5.1.20.

        * A new option, `--syslog-tag=TAG ', modifies the default tags
          written by `mysqld_safe' and `mysqld' to syslog to be
          `mysqld_safe-TAG ' and `mysqld-TAG' rather than the default
          tags of `mysqld_safe' and `mysqld'.

     (Bug#29992 (http://bugs.mysql.com/29992))

   * Transaction support in the `FEDERATED' storage engine has been
     disabled due to issues with multiple active transactions and
     sessions on the same `FEDERATED' table.  (Bug#29875
     (http://bugs.mysql.com/29875))

   * Previously, prepared statements processed using `PREPARE' and
     `EXECUTE' were not subject to caching in the query cache if they
     contained any `?' parameter markers. This limitation has been
     lifted.  (Bug#29318 (http://bugs.mysql.com/29318))

   * It is now possible to set `long_query_time' in microseconds or to
     0. Setting this value to 0 causes all queries to be recorded in
     the slow query log.

     Currently, fractional values can be used only when logging to
     files. We plan to provide this functionality for logging to tables
     when time-related data types are enhanced to support microsecond
     resolution.  (Bug#25412 (http://bugs.mysql.com/25412))

   * The SQL thread on a slave now is always allowed to enter `InnoDB'
     even if this would exceed the limit imposed by the
     `innodb_thread_concurrency' system variable. In cases of high load
     on the slave server (when `innodb_thread_concurrency' is reached),
     this change helps the slave stay more up to date with the master;
     in the previous behavior, the SQL thread was competing for
     resources with all client threads active on the slave server.
     (Bug#25078 (http://bugs.mysql.com/25078))

   * `INFORMATION_SCHEMA' implementation changes were made that
     optimize certain types of queries for `INFORMATION_SCHEMA' tables
     so that they execute more quickly.  *Note
     information-schema-optimization::, provides guidelines on how to
     take advantage of these optimizations by writing queries that
     minimize the need for the server to access the filesystem to
     obtain the information contained in `INFORMATION_SCHEMA' tables.
     By writing queries that enable the server to avoid directory scans
     or opening table files, you will obtain better performance.
     (Bug#19588 (http://bugs.mysql.com/19588))

   * Log table locking was redesigned, eliminating several lock-related
     problems:

        * Truncating `mysql.slow_log' in a stored procedure after use
          of a cursor caused the thread to lock.

        * Flushing a log table resulted in unnecessary warnings.

        * The server would hang when performing concurrent `ALTER
          TABLE' or `TRUNCATE TABLE' statements against the log tables.

        * Changing the value of the `general_log' system variable while
          a global read lock was in place resulted in deadlock.

     The changes provide better-defined interface characteristics.  See
     *Note log-tables::.  (Bug#17876 (http://bugs.mysql.com/17876),
     Bug#23044 (http://bugs.mysql.com/23044), Bug#25422
     (http://bugs.mysql.com/25422), Bug#29129
     (http://bugs.mysql.com/29129))

   * Added the `--commit', `--detach', `--post-system', and
     `--pre-system' options for `mysqlslap'.

   * Replication between master and slaves now supports different
     column numbers within a table on both master and slave. The rules
     for replication where the table definitions are different has also
     changed. This supercedes the functionality for replication from
     the master table to a slave table with more columns that was added
     in MySQL 5.1.12. For more information, see *Note
     replication-features-differing-tables::.

   * A new option, `--syslog-tag=TAG ', modifies the default tags
     written by `mysqld_safe' and `mysqld' to syslog to be
     `mysqld_safe-TAG ' and `mysqld-TAG ' rather than the default tags
     of `mysqld_safe' and `mysqld'.

   * Two options relating to slow query logging have been added for
     `mysqld'.  `--log-slow-slave-statements' causes slow statements
     executed by a replication slave to be written to the slow query
     log; `min_examined_row_limit' can be used to cause queries which
     examine fewer than the stated number of rows not to be logged.

Bugs fixed:

   * *Incompatible Change*: Several issues were identified for stored
     programs (stored functions and procedures, triggers, and events)
     and views containing non-ASCII symbols. These issues involved
     conversion errors due to incomplete character set information when
     translating these objects to and from stored format, such as:

        * Parsing the original object definition so that it can be
          stored.

        * Compiling the stored definition into executable form when the
          object is invoked.

        * Retrieval of object definitions from `INFORMATION_SCHEMA'
          tables.

        * Displaying the object definition in `SHOW' statements. This
          issue also affected `mysqldump', which uses `SHOW'.

     The fix for the problems is to store character set information
     from the object creation context so that this information is
     available when the object needs to be used later. The context
     includes the client character set, the connection character set
     and collation, and the collation of the database with which the
     object is associated.

     As a result of the patch, several tables have new columns:

        * In the `mysql' database, the `proc' and `event' tables now
          have these columns: `character_set_client',
          `collation_connection', `db_collation', `body_utf8'.

        * In `INFORMATION_SCHEMA', the `VIEWS' table now has these
          columns: `CHARACTER_SET_CLIENT', `COLLATION_CONNECTION'. The
          `ROUTINES', `TRIGGERS', and `EVENT' tables now have these
          columns: `CHARACTER_SET_CLIENT', `COLLATION_CONNECTION',
          `DATABASE_COLLATION'.

     These columns store the session values of the
     `character_set_client' and `collation_connection' system
     variables, and the collation of the database with which the object
     is associated. The values are those in effect at object creation
     time. (The saved database collation is not the value of the
     `collation_database' system variable, which applies to the default
     database; the database that contains the object is not necessarily
     the default database.)

     Several `SHOW' statements now display additional columns
     corresponding to the new table columns. These statements are:
     `SHOW CREATE EVENT', `SHOW CREATE FUNCTION', `SHOW CREATE
     PROCEDURE', `SHOW CREATE VIEW', `SHOW EVENTS', `SHOW FUNCTION
     STATUS', `SHOW PROCEDURE STATUS', `SHOW TRIGGERS'.

     A new statement, `SHOW CREATE TRIGGER' is introduced and is used
     by `mysqldump' for producing `CREATE TRIGGER' statements.

     Subsequent to the patch just described, it was discovered that the
     patch broke `mysql_upgrade'; this has been corrected.

     *Important*:

     The fixes for the problems just describe affect _all_ existing
     stored programs and views.  (For example, you will see warnings
     about `no creation context.') To avoid warnings from the server
     about the use of old definitions from any release prior to 5.1.21,
     you should dump stored programs and views with `mysqldump' after
     upgrading to 5.1.21, and then reload them to recreate them with
     new definitions. Invoke `mysqldump' with a
     `--default-character-set' option that names the non-ASCII
     character set that was used for the definitions when the objects
     were originally defined.

     (Bug#25221 (http://bugs.mysql.com/25221), Bug#21249
     (http://bugs.mysql.com/21249), Bug#30027
     (http://bugs.mysql.com/30027), Bug#16291
     (http://bugs.mysql.com/16291), Bug#11986
     (http://bugs.mysql.com/11986), Bug#25212
     (http://bugs.mysql.com/25212), Bug#19443
     (http://bugs.mysql.com/19443), Bug#30029
     (http://bugs.mysql.com/30029))

   * *MySQL Cluster*: `DELETE FROM TABLE WHERE PRIMARY_KEY IN
     (VALUE_LIST)', where the VALUE_LIST contained more than one value,
     called from an `AFTER DELETE' trigger on an `NDB' table, caused
     `mysqld' to crash.  (Bug#30337 (http://bugs.mysql.com/30337))

   * *MySQL Cluster*: When restarting a data node, queries could hang
     during that node's start phase 5, and continue only after the node
     had entered phase 6.  (Bug#29364 (http://bugs.mysql.com/29364))

   * *MySQL Cluster*: Replica redo logs were inconsistently handled
     during a system restart.  (Bug#29354 (http://bugs.mysql.com/29354))

   * *MySQL Cluster*: When a node failed to respond to a `COPY_GCI'
     signal as part of a global checkpoint, the master node was killed
     instead of the node that actually failed.  (Bug#29331
     (http://bugs.mysql.com/29331))

   * *MySQL Cluster*: An invalid comparison made during `REDO'
     validation that could lead to an `Error while reading REDO log'
     condition.  (Bug#29118 (http://bugs.mysql.com/29118))

   * *MySQL Cluster*: The wrong data pages were sometimes invalidated
     following a global checkpoint.  (Bug#29067
     (http://bugs.mysql.com/29067))

   * *MySQL Cluster*: If at least 2 files were involved in `REDO'
     invalidation, then file 0 of page 0 was not updated and so pointed
     to an invalid part of the redo log.  (Bug#29057
     (http://bugs.mysql.com/29057))

   * *MySQL Cluster*: If a storage engine has its own logging
     capability, then any statement using both this engine and some
     other engine not having its own logging could not be correctly
     logged, due to the fact that entries from one engine could be
     logged before entries from the other engine were. This did not
     generate any error messages when it occurred.

     Now, if multiple storage engines are used in a statement and at
     least one of them has its own logging capability, then an error
     message is generated and the statement is not executed.

     *Note*:

     Currently, the only storage engine to have its own logging
     capability is `NDBCLUSTER'.

     (Bug#28722 (http://bugs.mysql.com/28722))

   * *MySQL Cluster*: Warnings and errors generated by `ndb_config
     `--config-file=FILE'' were sent to `stdout', rather than to
     `stderr'.  (Bug#25941 (http://bugs.mysql.com/25941))

   * *MySQL Cluster*: When a cluster backup was terminated using the
     `ABORT BACKUP' command in the management client, a misleading
     error message `Backup aborted by application: Permanent error:
     Internal error' was returned. The error message returned in such
     cases now reads `Backup aborted by user request'.  (Bug#21052
     (http://bugs.mysql.com/21052))

   * *MySQL Cluster*: (Replication): Inconsistencies could occur
     between the master and the slave when replicating Disk Data tables.
     (Bug#19259 (http://bugs.mysql.com/19259), Bug#19227
     (http://bugs.mysql.com/19227))

   * *MySQL Cluster*: Large file support did not work in AIX server
     binaries.  (Bug#10776 (http://bugs.mysql.com/10776))

   * *Disk Data*: Performing Disk Data schema operations during a node
     restart could cause forced shutdowns of other data nodes.
     (Bug#29501 (http://bugs.mysql.com/29501))

   * *Disk Data*: When dropping a page, the stack's bottom entry could
     sometime be left `cold' rather than `hot', violating the rules for
     stack pruning.  (Bug#29176 (http://bugs.mysql.com/29176))

   * *Disk Data*: Disk data meta-information that existed in `ndbd'
     might not be visible to `mysqld'.  (Bug#28720
     (http://bugs.mysql.com/28720))

   * *Disk Data*: The number of free extents was incorrectly reported
     for some tablespaces.  (Bug#28642 (http://bugs.mysql.com/28642))

   * *Cluster Replication*: When executing a statement where
     `binlog_format=statement', the result of the statement was logged
     both as a statement and as rows.  (Bug#29222
     (http://bugs.mysql.com/29222))

   * *Cluster Replication*: `mysqld' would segfault on startup when the
     `NDB' storage engine was enabled and the default character set was
     a strictly multi-byte character set such as UCS2.

     This issue does _not_ apply to character sets that can contain
     single-byte characters in addition to multi-byte characters such
     as UTF-8.

     Additional issues remain with regard to the use of multi-byte
     character sets in MySQL Cluster Replication; see *Note
     mysql-cluster-replication-issues::, for more information.
     (Bug#27404 (http://bugs.mysql.com/27404))

   * Prepared statements containing `CONNECTION_ID()' could be written
     improperly to the binary log.  (Bug#30200
     (http://bugs.mysql.com/30200))

   * Use of local variables with non-ASCII names in stored procedures
     crashed the server.  (Bug#30120 (http://bugs.mysql.com/30120))

   * On Windows, client libraries lacked symbols required for linking.
     (Bug#30118 (http://bugs.mysql.com/30118))

   * `--myisam-recover=''' (empty option value) did not disable
     `MyISAM' recovery.  (Bug#30088 (http://bugs.mysql.com/30088))

   * For the `SHOW TABLE TYPES' statement, the server sent incorrect
     output to clients, possibly causing them to crash.  (Bug#30036
     (http://bugs.mysql.com/30036))

   * The `IS_UPDATABLE' column in the `INFORMATION_SCHEMA.VIEWS' table
     was not always set correctly.  (Bug#30020
     (http://bugs.mysql.com/30020))

   * `SHOW' statements were being written to the slow query log that
     should not have been.  (Bug#30000 (http://bugs.mysql.com/30000))

   * `REPAIR TABLE ... USE_FRM' could corrupt tables.  (Bug#29980
     (http://bugs.mysql.com/29980))

   * For `MyISAM' tables on Windows, `INSERT', `DELETE', or `UPDATE'
     followed by `ALTER TABLE' within `LOCK TABLES' could cause table
     corruption.  (Bug#29957 (http://bugs.mysql.com/29957))

   * LOCK TABLES did not pre-lock tables used in triggers of the locked
     tables. Unexpected locking behavior and statement failures similar
     to `failed: 1100: Table 'XX' was not locked with LOCK TABLES'
     could result.  (Bug#29929 (http://bugs.mysql.com/29929))

   * `INSERT ... VALUES(CONNECTION_ID(), ...)' statements were written
     to the binary log in such a way that they could not be properly
     restored.  (Bug#29928 (http://bugs.mysql.com/29928))

   * Adding `DISTINCT' could cause incorrect rows to appear in a query
     result.  (Bug#29911 (http://bugs.mysql.com/29911))

   * On Windows, the CMake build process did not produce the embedded
     server library or related binaries.  (Bug#29903
     (http://bugs.mysql.com/29903))

   * Using the `DATE()' function in a `WHERE' clause did not return any
     records after encountering `NULL'. However, using `TRIM' or `CAST'
     produced the correct results.  (Bug#29898
     (http://bugs.mysql.com/29898))

   * `SESSION_USER()' returned garbage data (rather than the correct
     value of the empty string) when executed by a slave SQL thread.
     (Bug#29878 (http://bugs.mysql.com/29878))

   * Very long prepared statements in stored procedures could cause a
     server crash.  (Bug#29856 (http://bugs.mysql.com/29856))

   * If query execution involved a temporary table, `GROUP_CONCAT()'
     could return a result with an incorrect character set.  (Bug#29850
     (http://bugs.mysql.com/29850))

   * If one thread was performing concurrent inserts, other threads
     reading from the same table using equality key searches could see
     the index values for new rows before the data values had been
     written, leading to reports of table corruption.  (Bug#29838
     (http://bugs.mysql.com/29838))

   * Repeatedly accessing a view in a stored procedure (for example, in
     a loop) caused a small amount of memory to be allocated per
     access. Although this memory is deallocated on disconnect, it
     could be a problem for a long running stored procedures that make
     repeated access of views.  (Bug#29834
     (http://bugs.mysql.com/29834))

   * `mysqldump' produced output that incorrectly discarded the
     `NO_AUTO_VALUE_ON_ZERO' value of the `SQL_MODE' variable after
     dumping triggers.  (Bug#29788 (http://bugs.mysql.com/29788))

   * An assertion failure occurred within yaSSL for very long keys.
     (Bug#29784 (http://bugs.mysql.com/29784))

   * For `MEMORY' tables, the `index_merge' union access method could
     return incorrect results.  (Bug#29740
     (http://bugs.mysql.com/29740))

   * Comparison of `TIME' values using the `BETWEEN' operator led to
     string comparison, producing incorrect results in some cases.  Now
     the values are compared as integers.  (Bug#29739
     (http://bugs.mysql.com/29739))

   * The thread ID was not reset properly after execution of *Note
     `mysql_change_user()': mysql-change-user, which could cause
     replication failure when replicating temporary tables.  (Bug#29734
     (http://bugs.mysql.com/29734))

   * For a table with a `DATE' column DATE_COL such that selecting rows
     with `WHERE DATE_COL = 'DATE_VAL 00:00:00'' yielded a non-empty
     result, adding `GROUP BY DATE_COL' caused the result to be empty.
     (Bug#29729 (http://bugs.mysql.com/29729))

   * In some cases, `INSERT INTO ... SELECT ... GROUP BY' could insert
     rows even if the `SELECT' by itself produced an empty result.
     (Bug#29717 (http://bugs.mysql.com/29717))

   * Single-row inserts could report a row count greater than one.
     (Bug#29692 (http://bugs.mysql.com/29692))

   * For the embedded server, the *Note `mysql_stmt_store_result()':
     mysql-stmt-store-result.  C API function caused a memory leak for
     empty result sets.  (Bug#29687 (http://bugs.mysql.com/29687))

   * `EXPLAIN' produced `Impossible where' for statements of the form
     `SELECT ...  FROM t WHERE c=0', where `c' was an `ENUM' column
     defined as a primary key.  (Bug#29661
     (http://bugs.mysql.com/29661))

   * On Windows, `ALTER TABLE' hung if records were locked in share
     mode by a long-running transaction.  (Bug#29644
     (http://bugs.mysql.com/29644))

   * `mysqld_safe' produced error messages and did not create the error
     log file under some circumstances.  (Bug#29634
     (http://bugs.mysql.com/29634))

   * On 64-bit platforms, the filesort code (for queries with `GROUP
     BY' or `ORDER BY') could crash due to an incorrect pointer size.
     (Bug#29610 (http://bugs.mysql.com/29610))

   * A left join between two views could produce incorrect results.
     (Bug#29604 (http://bugs.mysql.com/29604))

   * Certain statements with unions, subqueries, and joins could result
     in huge memory consumption.  (Bug#29582
     (http://bugs.mysql.com/29582))

   * Clients using SSL could hang the server.  (Bug#29579
     (http://bugs.mysql.com/29579))

   * A slave running with `--log-slave-updates' would fail to write
     `INSERT DELAY IGNORE' statements to its binary log, resulting in
     different binary log contents on the master and slave.  (Bug#29571
     (http://bugs.mysql.com/29571))

   * Storage engine error conditions in row-based replication were not
     correctly reported to the user.  (Bug#29570
     (http://bugs.mysql.com/29570))

   * An incorrect result was returned when comparing string values that
     were converted to `TIME' values with `CAST()'.  (Bug#29555
     (http://bugs.mysql.com/29555))

   * `gcov' coverage-testing information was not written if the server
     crashed.  (Bug#29543 (http://bugs.mysql.com/29543))

   * Conversion of ASCII DEL (`0x7F') to Unicode incorrectly resulted
     in QUESTION MARK (`0x3F') rather than DEL.  (Bug#29499
     (http://bugs.mysql.com/29499))

   * A field packet with `NULL' fields caused a `libmysqlclient' crash.
     (Bug#29494 (http://bugs.mysql.com/29494))

   * On Windows, the `mysql' client died if the user entered a
     statement and Return after entering Control-C.  (Bug#29469
     (http://bugs.mysql.com/29469))

   * The full-text parser could enter an infinite loop if it
     encountered an illegal multi-byte sequence or a sequence that has
     no mapping to Unicode.  (Bug#29464 (http://bugs.mysql.com/29464))

   * Failure to consider collation when comparing space characters
     could lead to incorrect index entry order, making it impossible to
     find some index values.  (Bug#29461 (http://bugs.mysql.com/29461))

   * Searching a `FULLTEXT' index for a word with the boolean mode
     truncation operator could cause an infinite loop.  (Bug#29445
     (http://bugs.mysql.com/29445))

   * Corrupt data resulted from use of `SELECT ... INTO OUTFILE
     'FILE_NAME' FIELDS ENCLOSED BY 'C'', where C is a digit or minus
     sign, followed by `LOAD DATA INFILE 'FILE_NAME' FIELDS ENCLOSED BY
     'C''.  (Bug#29442 (http://bugs.mysql.com/29442))

   * Killing an `INSERT DELAYED' thread caused a server crash.
     (Bug#29431 (http://bugs.mysql.com/29431))

   * Use of `SHOW BINLOG EVENTS' for a non-existent log file followed
     by `PURGE MASTER LOGS' caused a server crash.  (Bug#29420
     (http://bugs.mysql.com/29420))

   * Assertion failure could occur for grouping queries that employed
     `DECIMAL' user variables with assignments to them.  (Bug#29417
     (http://bugs.mysql.com/29417))

   * For `CAST(EXPR AS DECIMAL(M,D))', the limits of 65 and 30 on the
     precision (M) and scale (D) were not enforced.  (Bug#29415
     (http://bugs.mysql.com/29415))

   * Deleting from a `CSV' table could corrupt it.  (Bug#29411
     (http://bugs.mysql.com/29411))

   * Results for a select query that aliases the column names against a
     view could duplicate one column while omitting another. This bug
     could occur for a query over a multiple-table view that includes
     an `ORDER BY' clause in its definition.  (Bug#29392
     (http://bugs.mysql.com/29392))

   * `mysqldump' created a stray file when a given a too-long filename
     argument.  (Bug#29361 (http://bugs.mysql.com/29361))

   * The special `zero' `ENUM' value was coerced to the normal empty
     string `ENUM' value during a column-to-column copy. This affected
     `CREATE ... SELECT' statements and `SELECT' statements with
     aggregate functions on `ENUM' columns in the `GROUP BY' clause.
     (Bug#29360 (http://bugs.mysql.com/29360))

   * Inserting a negative number into a `CSV' table could corrupt it.
     (Bug#29353 (http://bugs.mysql.com/29353))

   * Optimization of queries with `DETERMINISTIC' stored functions in
     the `WHERE' clause was ineffective: A sequential scan was always
     used.  (Bug#29338 (http://bugs.mysql.com/29338))

   * `MyISAM' corruption could occur with the `cp932_japanese_ci'
     collation for the `cp932' character set due to incorrect
     comparison for trailing space.  (Bug#29333
     (http://bugs.mysql.com/29333))

   * For updates to `InnoDB' tables, a `TIMESTAMP' column with the `ON
     UPDATE CURRENT_TIMESTAMP' attribute could be updated even when no
     values actually changed.  (Bug#29310 (http://bugs.mysql.com/29310))

   * `FULLTEXT' indexes could be corrupted by certain `gbk' characters.
     (Bug#29299 (http://bugs.mysql.com/29299))

   * `SELECT ... INTO OUTFILE' followed by `LOAD DATA' could result in
     garbled characters when the `FIELDS ENCLOSED BY' clause named a
     delimiter of `'0'', `'b'', `'n'', `'r'', `'t'', `'N'', or `'Z''
     due to an interaction of character encoding and doubling for data
     values containing the enclosed-by character.  (Bug#29294
     (http://bugs.mysql.com/29294))

   * Sort order of the collation wasn't used when comparing trailing
     spaces. This could lead to incorrect comparison results,
     incorrectly created indexes, or incorrect result set order for
     queries that include an `ORDER BY' clause.  (Bug#29261
     (http://bugs.mysql.com/29261))

   * `CHECK TABLE' could erroneously report table corruption for a
     `CSV' table if multiple threads were modifying the table at the
     same time.  (Bug#29253 (http://bugs.mysql.com/29253))

   * Many threads accessing a `CSV' table simultaneously could cause an
     assertion failure.  (Bug#29252 (http://bugs.mysql.com/29252))

   * If an `ENUM' column contained `''' as one of its members
     (represented with numeric value greater than 0), and the column
     contained error values (represented as 0 and displayed as `'''),
     using `ALTER TABLE' to modify the column definition caused the 0
     values to be given the numeric value of the non-zero `''' member.
     (Bug#29251 (http://bugs.mysql.com/29251))

   * Calling *Note `mysql_options()': mysql-options. after *Note
     `mysql_real_connect()': mysql-real-connect. could cause clients to
     crash.  (Bug#29247 (http://bugs.mysql.com/29247))

   * `CHECK TABLE' for `ARCHIVE' tables could falsely report table
     corruption or cause a server crash.  (Bug#29207
     (http://bugs.mysql.com/29207))

   * Mixing binary and `utf8' columns in a union caused field lengths
     to be calculated incorrectly, resulting in truncation.  (Bug#29205
     (http://bugs.mysql.com/29205))

   * `AsText()' could fail with a buffer overrun.  (Bug#29166
     (http://bugs.mysql.com/29166))

   * Under some circumstances, a `SELECT ... FROM mysql.event' could
     cause the server to crash.  (Bug#29156
     (http://bugs.mysql.com/29156))

   * `InnoDB' refused to start on some versions of FreeBSD with
     LinuxThreads. This is fixed by enabling file locking on FreeBSD.
     (Bug#29155 (http://bugs.mysql.com/29155))

   * `LOCK TABLES' was not atomic when more than one `InnoDB' tables
     were locked.  (Bug#29154 (http://bugs.mysql.com/29154))

   * `INSERT DELAYED' statements on a master server are replicated as
     non-`DELAYED' inserts on slaves (which is normal, to preserve
     serialization), but the inserts on the slave did not use
     concurrent inserts. Now `INSERT DELAYED' on a slave is converted
     to a concurrent insert when possible, and to a normal insert
     otherwise.  (Bug#29152 (http://bugs.mysql.com/29152))

   * `mysqld' failed to exit during shutdown.  (Bug#29133
     (http://bugs.mysql.com/29133))

   * A network structure was initialized incorrectly, leading to
     embedded server crashes.  (Bug#29117 (http://bugs.mysql.com/29117))

   * An assertion failure occurred if a query contained a conjunctive
     predicate of the form ` VIEW_COLUMN = constant' in the `WHERE'
     clause and the `GROUP BY' clause contained a reference to a
     different view column. The fix also enables application of an
     optimization that was being skipped if a query contained a
     conjunctive predicate of the form `VIEW_COLUMN = constant' in the
     `WHERE' clause and the `GROUP BY' clause contained a reference to
     the same view column.  (Bug#29104 (http://bugs.mysql.com/29104))

   * A maximum of 4TB `InnoDB' free space was reported by `SHOW TABLE
     STATUS,' which is incorrect on systems with more than 4TB space.
     (Bug#29097 (http://bugs.mysql.com/29097))

   * If an `INSERT INTO ... SELECT' statement inserted into the same
     table that the `SELECT' retrieved from, and the `SELECT' included
     `ORDER BY' and `LIMIT' clauses, different data was inserted than
     the data produced by the `SELECT' executed by itself.  (Bug#29095
     (http://bugs.mysql.com/29095))

   * Queries that performed a lookup into a `BINARY' index containing
     key values ending with spaces caused an assertion failure for
     debug builds and incorrect results for non-debug builds.
     (Bug#29087 (http://bugs.mysql.com/29087))

   * The semantics of `BIGINT' depended on platform-specific
     characteristics.  (Bug#29079 (http://bugs.mysql.com/29079))

   * A byte-order issue in writing a spatial index to disk caused bad
     index files on some systems.  (Bug#29070
     (http://bugs.mysql.com/29070))

   * Creation of a legal stored procedure could fail if no default
     database had been selected.  (Bug#29050
     (http://bugs.mysql.com/29050))

   * `REPLACE', `INSERT IGNORE', and `UPDATE IGNORE' did not work for
     `FEDERATED' tables.  (Bug#29019 (http://bugs.mysql.com/29019))

   * Inserting into `InnoDB' tables and executing `RESET MASTER' in
     multiple threads cause assertion failure in debug server binaries.
     (Bug#28983 (http://bugs.mysql.com/28983))

   * Updates to a `CSV' table could cause a server crash or update the
     table with incorrect values.  (Bug#28971
     (http://bugs.mysql.com/28971))

   * For a `ucs2' column, `GROUP_CONCAT()' did not convert separators
     to the result character set before inserting them, producing a
     result containing a mixture of two different character sets.
     (Bug#28925 (http://bugs.mysql.com/28925))

   * Dropping the definer of an active event caused the server to crash.
     (Bug#28924 (http://bugs.mysql.com/28924))

   * For a join with `GROUP BY' and/or `ORDER BY' and a view reference
     in the `FROM' list, the query metadata erroneously showed empty
     table aliases and database names for the view columns.  (Bug#28898
     (http://bugs.mysql.com/28898))

   * Creating an event using `ON SCHEDULE AT CURRENT_TIMESTAMP +
     INTERVAL ...' could in some cases cause `mysqld' to crash.
     (Bug#28881 (http://bugs.mysql.com/28881))

   * Coercion of ASCII values to character sets that are a superset of
     ASCII sometimes was not done, resulting in `illegal mix of
     collations' errors. These cases now are resolved using repertoire,
     a new string expression attribute (see *Note charset-repertoire::).
     (Bug#28875 (http://bugs.mysql.com/28875))

   * Executing ALTER EVENT on an event whose definer's event creation
     privileges had been revoked cause the server to crash.  (Bug#28873
     (http://bugs.mysql.com/28873))

   * `ALTER VIEW' is not supported as a prepared statement but was not
     being rejected. `ALTER VIEW' is now prohibited as a prepared
     statement or when called within stored routines.  (Bug#28846
     (http://bugs.mysql.com/28846))

   * In strict SQL mode, errors silently stopped the SQL thread even
     for errors named using the `--slave-skip-errors' option.
     (Bug#28839 (http://bugs.mysql.com/28839))

   * Fast `ALTER TABLE' (that works without rebuilding the table)
     acquired duplicate locks in the storage engine. In `MyISAM', if
     `ALTER TABLE' was issued under `LOCK TABLE', it caused all data
     inserted after `LOCK TABLE' to disappear.  (Bug#28838
     (http://bugs.mysql.com/28838))

   * Runtime changes to the `log_queries_not_using_indexes' system
     variable were ignored.  (Bug#28808 (http://bugs.mysql.com/28808))

   * Selecting a column not present in the selected-from table caused
     an extra error to be produced by `SHOW ERRORS'.  (Bug#28677
     (http://bugs.mysql.com/28677))

   * Creating an event to be executed at a time close to the end of the
     allowed range (2038-01-19 03:14:07 UTC) would cause the server to
     crash.  (Bug#28641 (http://bugs.mysql.com/28641))

   * For a statement of the form `CREATE t1 SELECT INTEGER_CONSTANT',
     the server created the column using the `DECIMAL' data type for
     large negative values that are within the range of `BIGINT'.
     (Bug#28625 (http://bugs.mysql.com/28625))

   * Starting the server with an `innodb_force_recovery' value of 4 did
     not work.  (Bug#28604 (http://bugs.mysql.com/28604))

   * For `InnoDB' tables, MySQL unnecessarily sorted records in certain
     cases when the records were retrieved by `InnoDB' in the proper
     order already.  (Bug#28591 (http://bugs.mysql.com/28591))

   * `mysql_install_db' could fail to find script files that it needs.
     (Bug#28585 (http://bugs.mysql.com/28585))

   * If a stored procedure was created and invoked prior to selecting a
     default database with `USE', a `No database selected' error
     occurred.  (Bug#28551 (http://bugs.mysql.com/28551))

   * On Mac OS X, shared-library installation pathnames were incorrect.
     (Bug#28544 (http://bugs.mysql.com/28544))

   * Using the `--skip-add-drop-table 'option with `mysqldump'
     generated incorrect SQL if the database included any views. The
     recreation of views requires the creation and removal of temporary
     tables. This option suppressed the removal of those temporary
     tables. The same applied to `--compact' since this option also
     invokes `--skip-add-drop-table'.  (Bug#28524
     (http://bugs.mysql.com/28524))

   * `mysqlbinlog --hexdump' generated incorrect output due to omission
     of the ` `#' ' comment character for some comment lines.
     (Bug#28293 (http://bugs.mysql.com/28293))

   * `InnoDB' could crash if the server was shut down while
     `innodb_table_monitor' was running.  (Bug#28254
     (http://bugs.mysql.com/28254))

   * A race condition in the interaction between `MyISAM' and the query
     cache code caused the query cache not to invalidate itself for
     concurrently inserted data.  (Bug#28249
     (http://bugs.mysql.com/28249))

   * A duplicate-key error message could display an incorrect key value
     when not all columns of the key were used to select rows for
     update.  (Bug#28158 (http://bugs.mysql.com/28158))

   * Indexing column prefixes in `InnoDB' tables could cause table
     corruption.  (Bug#28138 (http://bugs.mysql.com/28138))

   * Index creation could fail due to truncation of key values to the
     maximum key length rather than to a mulitiple of the maximum
     character length.  (Bug#28125 (http://bugs.mysql.com/28125))

   * Instance Manager had a race condition when it received a shutdown
     request while a guarded `mysqld' instance was starting such that
     it could fail to stop the `mysqld' instance.  (Bug#28030
     (http://bugs.mysql.com/28030))

   * `SELECT ... FOR UPDATE' with partitioned tables could cause a
     server crash.  (Bug#28026 (http://bugs.mysql.com/28026))

   * On Windows, Instance Manager would crash if an instance object
     failed to initialize during startup. This could happen if an
     incorrect `mysqld' path was supplied in the configuration file.
     (Bug#28012 (http://bugs.mysql.com/28012))

   * The `LOCATE()' function returned `NULL' if any of its arguments
     evaluated to `NULL'. Likewise, the predicate, `LOCATE(STR,NULL) IS
     NULL', erroneously evaluated to `FALSE'.  (Bug#27932
     (http://bugs.mysql.com/27932))

   * Dropping a user-defined function could cause a server crash if the
     function was still in use by another thread.  (Bug#27564
     (http://bugs.mysql.com/27564))

   * An error that happened inside `INSERT', `UPDATE', or `DELETE'
     statements performed from within a stored function or trigger
     could cause inconsistency between master and slave servers.
     (Bug#27417 (http://bugs.mysql.com/27417))

   * For some event-creation problems, the server displayed messages
     that implied the problems were errors when they were only warnings.
     (Bug#27406 (http://bugs.mysql.com/27406))

   * Unsafe aliasing in the source caused a client library crash when
     compiled with `gcc' 4 at high optimization levels.  (Bug#27383
     (http://bugs.mysql.com/27383))

   * Index-based range reads could fail for comparisons that involved
     contraction characters (such as `ch' in Czech or `ll' in Spanish).
     (Bug#27345 (http://bugs.mysql.com/27345))

   * Aggregations in subqueries that refer to outer query columns were
     not always correctly referenced to the proper outer query.
     (Bug#27333 (http://bugs.mysql.com/27333))

   * Error returns from the `time()' system call were ignored.
     (Bug#27198 (http://bugs.mysql.com/27198))

   * Phantom reads could occur under `InnoDB' serializable isolation
     level.  (Bug#27197 (http://bugs.mysql.com/27197))

   * The `SUBSTRING()' function returned the entire string instead of
     an empty string when it was called from a stored procedure and
     when the length parameter was specified by a variable with the
     value ` `0' '.  (Bug#27130 (http://bugs.mysql.com/27130))

   * Some functions when used in partitioning expressions could cause
     `mysqld' to crash.  (Bug#27084 (http://bugs.mysql.com/27084))

   * The server acquired a global mutex for temporary tables, although
     such tables are thread-specific. This affected performance by
     blocking other threads.  (Bug#27062 (http://bugs.mysql.com/27062))

   * `FEDERATED' tables had an artificially low maximum of key length.
     (Bug#26909 (http://bugs.mysql.com/26909))

   * Updates to rows in a partitioned table could update the wrong
     column.  (Bug#26827 (http://bugs.mysql.com/26827))

   * Index creation could corrupt the table definition in the `.frm'
     file: 1) A table with the maximum number of key segments and
     maximum length key name would have a corrupted `.frm' file, due to
     incorrect calculation of the total key length. 2) `MyISAM' would
     reject a table with the maximum number of keys and the maximum
     number of key segments in all keys. (It would allow one less than
     this total maximum.) Now `MyISAM' accepts a table defined with the
     maximum.  (Bug#26642 (http://bugs.mysql.com/26642))

   * The Windows implementation of `pthread_join()' was incorrect and
     could cause crashes.  (Bug#26564 (http://bugs.mysql.com/26564))

   * After the first read of a `TEMPORARY' table, `CHECK TABLE' could
     report the table as being corrupt.  (Bug#26325
     (http://bugs.mysql.com/26325))

   * If an operation had an `InnoDB' table, and two triggers, `AFTER
     UPDATE' and `AFTER INSERT', competing for different resources
     (such as two distinct `MyISAM' tables), the triggers were unable
     to execute concurrently. In addition, `INSERT' and `UPDATE'
     statements for the `InnoDB' table were unable to run concurrently.
     (Bug#26141 (http://bugs.mysql.com/26141))

   * A number of unsupported constructs -- including prohibited
     constructs, the `UCASE()' function, and nested function calls --
     were permitted in partitioning expressions.  (Bug#26082
     (http://bugs.mysql.com/26082), Bug#18198
     (http://bugs.mysql.com/18198), Bug#29308
     (http://bugs.mysql.com/29308))

   * `ALTER DATABASE' did not require at least one option.  (Bug#25859
     (http://bugs.mysql.com/25859))

   * The index merge union access algorithm could produce incorrect
     results with `InnoDB' tables. The problem could also occur for
     queries that used `DISTINCT'.  (Bug#25798
     (http://bugs.mysql.com/25798))

   * When using a `FEDERATED' table, the value of `last_insert_id()'
     would not correctly update the C API interface, which would affect
     the autogenerated ID returned both through the C API and the MySQL
     protocol, affecting Connectors that used the protocol and/or C API.
     (Bug#25714 (http://bugs.mysql.com/25714))

   * The server was blocked from opening other tables while the
     `FEDERATED' engine was attempting to open a remote table. Now the
     server does not check the correctness of a `FEDERATED' table at
     `CREATE TABLE' time, but waits until the table actually is
     accessed.  (Bug#25679 (http://bugs.mysql.com/25679))

   * Under ActiveState Perl, `mysql-test-run.pl' could kill itself when
     attempting to kill other processes.  (Bug#25657
     (http://bugs.mysql.com/25657))

   * Several `InnoDB' assertion failures were corrected.  (Bug#25645
     (http://bugs.mysql.com/25645))

   * A query with `DISTINCT' in the select list to which the loose-scan
     optimization for grouping queries was applied returned an
     incorrect result set when the query was used with the
     `SQL_BIG_RESULT' option.  (Bug#25602 (http://bugs.mysql.com/25602))

   * For a multiple-row insert into a `FEDERATED' table that refers to
     a remote transactional table, if the insert failed for a row due
     to constraint failure, the remote table would contain a partial
     commit (the rows preceding the failed one) instead of rolling back
     the statement completely. This occurred because the rows were
     treated as individual inserts.

     Now `FEDERATED' performs bulk-insert handling such that multiple
     rows are sent to the remote table in a batch.  This provides a
     performance improvement and enables the remote table to perform
     statement rollback properly should an error occur. This capability
     has the following limitations:

        * The size of the insert cannot exceed the maximum packet size
          between servers. If the insert exceeds this size, it is
          broken into multiple packets and the rollback problem can
          occur.

        * Bulk-insert handling does not occur for `INSERT ...  ON
          DUPLICATE KEY UPDATE'.

     (Bug#25513 (http://bugs.mysql.com/25513))

   * The `FEDERATED' storage engine failed silently for `INSERT ... ON
     DUPLICATE KEY UPDATE' if a duplicate key violation occurred.
     `FEDERATED' does not support `ON DUPLICATE KEY UPDATE', so now it
     correctly returns an `ER_DUP_KEY' error if a duplicate key
     violation occurs.  (Bug#25511 (http://bugs.mysql.com/25511))

   * In a stored function or trigger, when `InnoDB' detected deadlock,
     it attempted rollback and displayed an incorrect error message
     (`Explicit or implicit commit is not allowed in stored function or
     trigger'). Now `InnoDB' returns an error under these conditions
     and does not attempt rollback. Rollback is handled outside of
     `InnoDB' above the function/trigger level.  (Bug#24989
     (http://bugs.mysql.com/24989))

   * Dropping a temporary `InnoDB' table that had been locked with
     `LOCK TABLES' caused a server crash.  (Bug#24918
     (http://bugs.mysql.com/24918))

   * On Windows, executables did not include Vista manifests.
     (Bug#24732 (http://bugs.mysql.com/24732)) See also Bug#22563
     (http://bugs.mysql.com/22563)

   * Slave servers could incorrectly interpret an out-of-memory error
     from the master and reconnect using the wrong binary log position.
     (Bug#24192 (http://bugs.mysql.com/24192))

   * If MySQL/`InnoDB' crashed very quickly after starting up, it would
     not force a checkpoint. In this case, `InnoDB' would skip crash
     recovery at next startup, and the database would become corrupt.
     Now, if the redo log scan at `InnoDB' startup goes past the last
     checkpoint, crash recovery is forced.  (Bug#23710
     (http://bugs.mysql.com/23710))

   * Using the `READ COMMITTED' transaction isolation level caused
     mixed and statement-based replication to fail.  (Bug#23051
     (http://bugs.mysql.com/23051))

   * `SHOW INNODB STATUS' caused an assertion failure under high load.
     (Bug#22819 (http://bugs.mysql.com/22819))

   * `SHOW BINLOG EVENTS' displayed incorrect values of `End_log_pos'
     for events associated with transactional storage engines.
     (Bug#22540 (http://bugs.mysql.com/22540))

   * When determining which transaction to kill after deadlock has been
     detected, `InnoDB' now adds the number of locks to a transaction's
     weight, and avoids killing transactions that mave modified
     non-transactional tables. This should reduce the likelihood of
     killing long-running transactions containing `SELECT ... FOR
     UPDATE' or `INSERT/REPLACE INTO ... SELECT' statements, and of
     causing partial updates if the target is a `MyISAM' table.
     (Bug#21293 (http://bugs.mysql.com/21293))

   * `InnoDB' displayed an incorrect error message when a `CREATE
     TABLE' statement exceeded the `InnoDB' maximum allowable row size.
     (Bug#21101 (http://bugs.mysql.com/21101))

   * Under heavy load with a large query cache, invalidating part of
     the cache could cause the server to freeze (that is, to be unable
     to service other operations until the invalidation was complete).
     (Bug#21074 (http://bugs.mysql.com/21074))

   * On Windows, the server used 10MB of memory for each connection
     thread, resulting in memory exhaustion. Now each thread uses 1MB.
     (Bug#20815 (http://bugs.mysql.com/20815))

   * `InnoDB' produced an unnecessary (and harmless) warning:
     ``InnoDB': Error: trying to declare trx to enter `InnoDB', but
     `InnoDB': it already is declared'.  (Bug#20090
     (http://bugs.mysql.com/20090))

   * If a slave timed out while registering with the master to which it
     was connecting, auto-reconnect failed thereafter.  (Bug#19328
     (http://bugs.mysql.com/19328))

   * If `InnoDB' reached its limit on the number of concurrent
     transactions (1023), it wrote a descriptive message to the error
     log but returned a misleading error message to the client, or an
     assertion failure occurred.  (Bug#18828
     (http://bugs.mysql.com/18828))

   * Under ActiveState Perl, `mysql-test-run.pl' would not run.
     (Bug#18415 (http://bugs.mysql.com/18415))

   * The server crashed when the size of an `ARCHIVE' table grew larger
     than 2GB.  (Bug#15787 (http://bugs.mysql.com/15787))

   * `SQL_BIG_RESULT' had no effect for `CREATE TABLE ... SELECT
     SQL_BIG_RESULT ...' statements.  (Bug#15130
     (http://bugs.mysql.com/15130))

   * On 64-bit Windows systems, the Config Wizard failed to complete
     the setup because 64-bit Windows does not resolve dynamic linking
     of the 64-bit `libmysql.dll' to a 32-bit application like the
     Config Wizard.  (Bug#14649 (http://bugs.mysql.com/14649))

   * `mysql_setpermission' tried to grant global-only privileges at the
     database level.  (Bug#14618 (http://bugs.mysql.com/14618))

   * For the general query log, logging of prepared statements executed
     via the C API differed from logging of prepared statements
     performed with `PREPARE' and `EXECUTE'. Logging for the latter was
     missing the `Prepare' and `Execute' lines.  (Bug#13326
     (http://bugs.mysql.com/13326))

   * The `TABLE_COMMENT' column for `INFORMATION_SCHEMA.TABLES'
     displayed extraneous information for `InnoDB' tables.  (Bug#11379
     (http://bugs.mysql.com/11379)) See also Bug#32440
     (http://bugs.mysql.com/32440)

   * The server returned data from `SHOW CREATE TABLE' statement or a
     `SELECT' statement on an INFORMATION_SCHEMA table using the
     `binary' character set.  (Bug#10491 (http://bugs.mysql.com/10491))

   * Backup software can cause `ERROR_SHARING_VIOLATION' or
     `ERROR_LOCK_VIOLATION' conditions during file operations. `InnoDB'
     now retries forever until the condition goes away.  (Bug#9709
     (http://bugs.mysql.com/9709))

   * Retrieval of object definitions from `INFORMATION_SCHEMA' tables.

   * In `INFORMATION_SCHEMA', the `VIEWS' table now has these columns:
     `CHARACTER_SET_CLIENT', `COLLATION_CONNECTION'. The `ROUTINES',
     `TRIGGERS', and `EVENT' tables now have these columns:
     `CHARACTER_SET_CLIENT', `COLLATION_CONNECTION',
     `DATABASE_COLLATION'.

   * In the `mysql' database, the `proc' and `event' tables now have
     these columns: `character_set_client', `collation_connection',
     `db_collation', `body_utf8'.

   * Displaying the object definition in `SHOW' statements. This issue
     also affected `mysqldump', which uses `SHOW'.

   * Compiling the stored definition into executable form when the
     object is invoked.

   * Bulk-insert handling does not occur for `INSERT ... ON DUPLICATE
     KEY UPDATE'.

   * The size of the insert cannot exceed the maximum packet size
     between servers. If the insert exceeds this size, it is broken
     into multiple packets and the rollback problem can occur.

   * Parsing the original object definition so that it can be stored.


File: manual.info,  Node: news-5-1-20,  Next: news-5-1-19,  Prev: news-5-1-21,  Up: news-5-1-x

C.1.10 Changes in MySQL 5.1.20 (25 June 2007)
---------------------------------------------

This is a new Beta development release, fixing recently discovered bugs.

*Note*:

This Beta release, as any other pre-production release, should not be
installed on _production_ level systems or systems with critical data.
It is good practice to back up your data before installing any new
version of software.  Although MySQL has worked very hard to ensure a
high level of quality, protect your data by making a backup as you
would for any software beta release. Please refer to our bug database at
`http://bugs.mysql.com/' for more details about the individual bugs
fixed in this version.

This section documents all changes and bug fixes that have been applied
since the last official MySQL release. If you would like to receive
more fine-grained and personalized _update alerts_ about fixes that are
relevant to the version and features you use, please consider
subscribing to _MySQL Enterprise_ (a commercial MySQL offering). For
more details please see `http://www.mysql.com/products/enterprise'.

Functionality added or changed:

   * *Incompatible Change*: It is no longer possible to partition the
     log tables.  (Bug#27816 (http://bugs.mysql.com/27816))

   * *Incompatible Change*: `mysqld_safe' now supports error logging to
     `syslog' on systems that support the `logger' command. The new
     `--syslog' and `--skip-syslog' options can be used instead of the
     `--log-error' option to control logging behavior, as described in
     *Note mysqld-safe::. The default is to use `syslog', which differs
     from the previous default behavior of writing an error log file.

     *Currently, logging to `syslog' may fail to operate correctly in
     some cases, so we recommend that you use `--skip-syslog' or
     `--log-error'.* To maintain the older behavior if you were using
     no error-logging option, use `--skip-syslog'. If you were using
     `--log-error', continue to use it.

     Note: In 5.1.21, the default is changed to `--skip-syslog', which
     is compatible with releases prior to 5.1.20.  (Bug#4858
     (http://bugs.mysql.com/4858))

   * *Important Change*: *MySQL Cluster*: The
     `TimeBetweenWatchdogCheckInitial' configuration parameter was
     added to allow setting of a separate watchdog timeout for memory
     allocation during startup of the data nodes. See *Note
     mysql-cluster-ndbd-definition::, for more information.  (Bug#28899
     (http://bugs.mysql.com/28899))

   * *MySQL Cluster*: The cluster management client now stores command
     history between sessions.  (Bug#29073
     (http://bugs.mysql.com/29073))

   * *MySQL Cluster*: `auto_increment_increment' and
     `auto_increment_offset' are now supported for `NDB' tables.
     (Bug#26342 (http://bugs.mysql.com/26342))

   * *MySQL Cluster*: The server source tree now includes scripts to
     simplify building MySQL with SCI support. For more information
     about SCI interconnects and these build scripts, see *Note
     mysql-cluster-sci-sockets::.  (Bug#25470
     (http://bugs.mysql.com/25470))

   * *MySQL Cluster*: A new configuration parameter `ODirect' causes
     `NDB' to attempt using `O_DIRECT' writes for LCP, backups, and redo
     logs, often lowering CPU usage.

   * If a `MERGE' table cannot be opened or used because of a problem
     with an underlying table, `CHECK TABLE' now displays information
     about which table caused the problem.  (Bug#26976
     (http://bugs.mysql.com/26976))

   * User variables and stored procedure variables are now supported
     for use in XPath expressions employed as arguments to the
     `ExtractValue()' and `UpdateXML()' functions.

     This means that:

        * XPath can now be used to load data from XML files using
          virtually any format, and so able to import data from most
          third party software which either has XML export
          functionality, or uses XML natively as a storage format.

        * Various complex conditions can be put on rows and columns, so
          one can filter for desired rows (or skip unwanted rows) when
          loading XML.

        * Various types of preprocessing using SQL functions are now
          possible when loading XML. For example, you can concatenate
          two XML tag or attribute values into a single column value
          using `CONCAT()', or remove some parts of the data using
          `REPLACE()'.

     See *Note xml-functions::, for more information.  (Bug#26518
     (http://bugs.mysql.com/26518))

   * Binary distributions for some platforms did not include shared
     libraries; now shared libraries are shipped for all platforms
     except AIX 5.2 64-bit. _Exception_: The library for the
     `libmysqld' embedded server is not shared except on Windows.
     (Bug#16520 (http://bugs.mysql.com/16520), Bug#26767
     (http://bugs.mysql.com/26767), Bug#13450
     (http://bugs.mysql.com/13450))

   * Added a new `PAD_CHAR_TO_FULL_LENGTH' SQL mode.  By default,
     trailing spaces are trimmed from `CHAR' column values on
     retrieval. If `PAD_CHAR_TO_FULL_LENGTH' is enabled, trimming does
     not occur and retrieved `CHAR' values are padded to their full
     length. This mode does not apply to `VARCHAR' columns, for which
     trailing spaces are retained on retrieval.

   * XPath can now be used to load data from XML files using virtually
     any format, and so able to import data from most third party
     software which either has XML export functionality, or uses XML
     natively as a storage format.

   * Various complex conditions can be put on rows and columns, so one
     can filter for desired rows (or skip unwanted rows) when loading
     XML.

   * The `SQL_MODE', `FOREIGN_KEY_CHECKS', `UNIQUE_CHECKS', character
     set/collations, and `SQL_AUTO_IS_NULL' sesstion variables are
     written to the binary log and honoured during replication. See
     *Note binary-log::.

   * Various types of preprocessing using SQL functions are now
     possible when loading XML. For example, you can concatenate two
     XML tag or attribute values into a single column value using
     `CONCAT()', or remove some parts of the data using `REPLACE()'.

Bugs fixed:

   * *Security Fix*: A malformed password packet in the connection
     protocol could cause the server to crash. Thanks for Dormando for
     reporting this bug, and for providing details and a proof of
     concept.  (Bug#28984 (http://bugs.mysql.com/28984), CVE-2007-3780
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-3780))

   * *Security Fix*: `CREATE TABLE LIKE' did not require any privileges
     on the source table. Now it requires the `SELECT' privilege.

     In addition, `CREATE TABLE LIKE' was not isolated from alteration
     by other connections, which resulted in various errors and
     incorrect binary log order when trying to execute concurrently a
     `CREATE TABLE LIKE' statement and either DDL statements on the
     source table or DML or DDL statements on the target table.
     (Bug#23667 (http://bugs.mysql.com/23667), Bug#25578
     (http://bugs.mysql.com/25578), CVE-2007-3781
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-3781))

   * *Incompatible Change*: Some error codes had error numbers in MySQL
     5.1 different from the numbers in MySQL 5.0. In MySQL 5.1, error
     numbers have been changed to match the MySQL 5.0 values: Error
     codes with value of 1458 or higher have changed in MySQL 5.1 now.
     Client applications designed to work with MySQL 5.1 with hard-coded
     error code values (for example, in statements such as `if
     (mysql_errno(mysql) == 1463) { ... }') need to be updated in the
     source code. All clients designed to work with MySQL 5.1 that test
     error codes (for example, in statements such as `if
     (mysql_errno(mysql) == ER_VIEW_RECURSIVE) { ... }') should be
     recompiled. Existing 5.0 clients should now work, without changes
     or recompilation, against servers for MySQL 5.1.20 or higher.
     (Bug#29245 (http://bugs.mysql.com/29245))

   * *Incompatible Change*: When `mysqldump' was run with the
     `--delete-master-logs' option, binary log files were deleted
     before it was known that the dump had succeeded, not after. (The
     method for removing log files used `RESET MASTER' prior to the
     dump. This also reset the binary log sequence numbering to
     `.000001'.) Now `mysqldump' flushes the logs (which creates a new
     binary log number with the next sequence number), performs the
     dump, and then uses `PURGE MASTER LOGS' to remove the log files
     older than the new one. This also preserves log numbering because
     the new log with the next number is generated and only the
     preceding logs are removed. However, this may affect applications
     if they rely on the log numbering sequence being reset.
     (Bug#24733 (http://bugs.mysql.com/24733))

   * *Incompatible Change*: The use of an `ORDER BY' or `DISTINCT'
     clause with a query containing a call to the `GROUP_CONCAT()'
     function caused results from previous queries to be redisplayed in
     the current result. The fix for this includes replacing a `BLOB'
     value used internally for sorting with a `VARCHAR'. This means
     that for long results (more than 65,535 bytes), it is possible for
     truncation to occur; if so, an appropriate warning is issued.
     (Bug#23856 (http://bugs.mysql.com/23856), Bug#28273
     (http://bugs.mysql.com/28273))

   * *MySQL Cluster*: Memory corruption could occur due to a problem in
     the `DBTUP' kernel block.  (Bug#29229
     (http://bugs.mysql.com/29229))

   * *MySQL Cluster*: A query having a large `IN(...)' or `NOT IN(...)'
     list in the `WHERE' condition on an `NDB' table could cause
     `mysqld' to crash.  (Bug#29185 (http://bugs.mysql.com/29185))

   * *MySQL Cluster*: In the event that two data nodes in the same node
     group and participating in a GCP crashed before they had written
     their respective `P0.sysfile' files, `QMGR' could refuse to start,
     issuing an invalid `Insufficient nodes for restart' error instead.
     (Bug#29167 (http://bugs.mysql.com/29167))

   * *MySQL Cluster*: Attempting to restore a `NULL' row to a
     `VARBINARY' column caused `ndb_restore' to fail.  (Bug#29103
     (http://bugs.mysql.com/29103))

   * *MySQL Cluster*: `ndb_error_reporter' now preserves timestamps on
     files.  (Bug#29074 (http://bugs.mysql.com/29074))

   * *MySQL Cluster*: It is now possible to set the maximum size of the
     allocation unit for table memory using the `MaxAllocate'
     configuration parameter.  (Bug#29044 (http://bugs.mysql.com/29044))

   * *MySQL Cluster*: When shutting down `mysqld', the `NDB' binlog
     process was not shut down before log cleanup began.  (Bug#28949
     (http://bugs.mysql.com/28949))

   * *MySQL Cluster*: `ndb_mgm' could hang when connecting to a
     nonexistent host.  (Bug#28847 (http://bugs.mysql.com/28847))

   * *MySQL Cluster*: A regression in the heartbeat monitoring code
     could lead to node failure under high load. This issue affected
     MySQL 5.1.19 and MySQL Cluster NDB 6.1.10 only.  (Bug#28783
     (http://bugs.mysql.com/28783))

   * *MySQL Cluster*: A corrupt schema file could cause a `File already
     open' error.  (Bug#28770 (http://bugs.mysql.com/28770))

   * *MySQL Cluster*: Having large amounts of memory locked caused
     swapping to disk.  (Bug#28751 (http://bugs.mysql.com/28751))

   * *MySQL Cluster*: Setting `InitialNoOpenFiles' equal to
     `MaxNoOfOpenFiles' caused an error. This was due to the fact that
     the actual value of `MaxNoOfOpenFiles' as used by the cluster was
     offset by 1 from the value set in `config.ini'.  (Bug#28749
     (http://bugs.mysql.com/28749))

   * *MySQL Cluster*: LCP files were not removed following an initial
     system restart.  (Bug#28726 (http://bugs.mysql.com/28726))

   * *MySQL Cluster*: `UPDATE IGNORE' statements involving the primary
     keys of multiple tables could result in data corruption.
     (Bug#28719 (http://bugs.mysql.com/28719))

   * *MySQL Cluster*: A race condition could result when non-master
     nodes (in addition to the master node) tried to update active
     status due to a local checkpoint (that is, between `NODE_FAILREP'
     and `COPY_GCIREQ' events). Now only the master updates the active
     status.  (Bug#28717 (http://bugs.mysql.com/28717))

   * *MySQL Cluster*: A fast global checkpoint under high load with
     high usage of the redo buffer caused data nodes to fail.
     (Bug#28653 (http://bugs.mysql.com/28653))

   * *MySQL Cluster*: The management client's response to `START BACKUP
     WAIT COMPLETED' did not include the backup ID.  (Bug#27640
     (http://bugs.mysql.com/27640))

   * *MySQL Cluster*: (Replication): A replicated unique key allowed
     duplicate key inserts on the slave.  (Bug#27044
     (http://bugs.mysql.com/27044))

   * *Replication*: It was possible to set `SQL_SLAVE_SKIP_COUNTER'
     such that the slave would jump into the middle of an event group.
     (Bug#28618 (http://bugs.mysql.com/28618)) See also Bug#12691
     (http://bugs.mysql.com/12691)

   * *Disk Data*: When loading data into a cluster following a version
     upgrade, the data nodes could forcibly shut down due to page and
     buffer management failures (that is, `ndbrequire' failures in
     `PGMAN').  (Bug#28525 (http://bugs.mysql.com/28525))

   * *Disk Data*: Repeated `INSERT' and `DELETE' operations on a Disk
     Data table having one or more large `VARCHAR' columns could cause
     data nodes to fail.  (Bug#20612 (http://bugs.mysql.com/20612))

   * *Cluster Replication*: When replicating `MyISAM' or `InnoDB'
     tables to a MySQL Cluster, it was not possible to determine
     exactly what had been applied following a shutdown of the slave
     cluster or `mysqld' process.  (Bug#26783
     (http://bugs.mysql.com/26783))

   * *Cluster API*: The timeout set using the MGM API
     `ndb_mgm_set_timeout()' function was incorrectly interpreted as
     seconds rather than as milliseconds.  (Bug#29063
     (http://bugs.mysql.com/29063))

   * *Cluster API*: An invalid error code could be set on transaction
     objects by `BLOB' handling code.  (Bug#28724
     (http://bugs.mysql.com/28724))

   * The `TRUNCATE' statement was handled differently by the server
     when row-based logging was in effect, even though the binlogging
     format in effect does not effect the fact that `TRUNCATE' is
     always logged as a statement.  (Bug#29130
     (http://bugs.mysql.com/29130))

   * If one of the queries in a `UNION' used the `SQL_CACHE' option and
     another query in the `UNION' contained a nondeterministic function,
     the result was still cached. For example, this query was
     incorrectly cached:


          SELECT NOW() FROM t1 UNION SELECT SQL_CACHE 1 FROM t1;

     (Bug#29053 (http://bugs.mysql.com/29053))

   * `DROP USER' statements that named multiple users, only some of
     which could be dropped, were replicated incorrectly.  (Bug#29030
     (http://bugs.mysql.com/29030))

   * Long pathnames for internal temporary tables could cause stack
     overflows.  (Bug#29015 (http://bugs.mysql.com/29015))

   * Using an `INTEGER' column from a table to `ROUND()' a number
     produced different results than using a constant with the same
     value as the `INTEGER' column.  (Bug#28980
     (http://bugs.mysql.com/28980))

   * Using events in replication could cause the slave to crash.
     (Bug#28953 (http://bugs.mysql.com/28953))

   * If a program binds a given number of parameters to a prepared
     statement handle and then somehow changes `stmt->param_count' to a
     different number, *Note `mysql_stmt_execute()':
     mysql-stmt-execute. could crash the client or server.  (Bug#28934
     (http://bugs.mysql.com/28934))

   * Queries using UDFs or stored functions were cached.  (Bug#28921
     (http://bugs.mysql.com/28921))

   * `INSERT .. ON DUPLICATE KEY UPDATE' could under some circumstances
     silently update rows when it should not have.  (Bug#28904
     (http://bugs.mysql.com/28904))

   * Queries that used `UUID()' were incorrectly allowed into the query
     cache. (This should not happen because `UUID()' is
     non-deterministic.)  (Bug#28897 (http://bugs.mysql.com/28897))

   * Using a `VIEW' created with a non-existing `DEFINER' could lead to
     incorrect results under some circumstances.  (Bug#28895
     (http://bugs.mysql.com/28895))

   * For `InnoDB' tables that use the `utf8' character set, incorrect
     results could occur for DML statements such as `DELETE' or
     `UPDATE' that use an index on character-based columns.  (Bug#28878
     (http://bugs.mysql.com/28878)) See also Bug#29449
     (http://bugs.mysql.com/29449), Bug#30485
     (http://bugs.mysql.com/30485), Bug#31395
     (http://bugs.mysql.com/31395)

     This regression was introduced by Bug#13195
     (http://bugs.mysql.com/13195)

   * Non-`utf8' characters could get mangled when stored in `CSV'
     tables.  (Bug#28862 (http://bugs.mysql.com/28862))

   * On Windows, `USE_TLS' was not defined for `mysqlclient.lib'.
     (Bug#28860 (http://bugs.mysql.com/28860))

   * In MySQL 5.1.15, a new error code `ER_DUP_ENTRY_WITH_KEY_NAME'
     (1582) was introduced to replace `ER_DUP_ENTRY' (1062) so that the
     key name could be provided instead of the key number.  This was
     unnecessary, so `ER_DUP_ENTRY' is used again and the key name is
     printed. The incompatibility introduced in 5.1.15 no longer
     applies.  (Bug#28842 (http://bugs.mysql.com/28842))

   * A subquery with `ORDER BY' and `LIMIT 1' could cause a server
     crash.  (Bug#28811 (http://bugs.mysql.com/28811))

   * Running `SHOW TABLE STATUS' while performing a high number of
     inserts on partitioned tables with a great many partitions could
     cause the server to crash.  (Bug#28806
     (http://bugs.mysql.com/28806))

   * Using `BETWEEN' with non-indexed date columns and short formats of
     the date string could return incorrect results.  (Bug#28778
     (http://bugs.mysql.com/28778))

   * Selecting `GEOMETRY' columns in a `UNION' caused a server crash.
     (Bug#28763 (http://bugs.mysql.com/28763))

   * When constructing the path to the original `.frm' file, `ALTER ..
     RENAME' was unnecessarily (and incorrectly) lowercasing the entire
     path when not on a case-insensitive filesystem, causing the
     statement to fail.  (Bug#28754 (http://bugs.mysql.com/28754))

   * The `binlog_format' system variable value was empty if the server
     was started with binary logging disabled.  Now it is set to
     `MIXED'.  (Bug#28752 (http://bugs.mysql.com/28752))

   * Searches on indexed and non-indexed `ENUM' columns could return
     different results for empty strings.  (Bug#28729
     (http://bugs.mysql.com/28729))

   * Executing `EXPLAIN EXTENDED' on a query using a derived table over
     a grouping subselect could lead to a server crash. This occurred
     only when materialization of the derived tables required creation
     of an auxiliary temporary table, an example being when a grouping
     operation was carried out with usage of a temporary table.
     (Bug#28728 (http://bugs.mysql.com/28728))

   * The result of evaluation for a view's `CHECK OPTION' option over
     an updated record and records of merged tables was arbitrary and
     dependant on the order of records in the merged tables during the
     execution of the `SELECT' statement.  (Bug#28716
     (http://bugs.mysql.com/28716))

   * The `manager thread' of the LinuxThreads implementation was
     unintentionally started before `mysqld' had dropped privileges (to
     run as an unprivileged user). This caused signaling between
     threads in `mysqld' to fail when the privileges were finally
     dropped.  (Bug#28690 (http://bugs.mysql.com/28690))

   * Setting an interval of `EVERY 0 SECOND' for a scheduled event
     caused the server to crash.  (Bug#28666
     (http://bugs.mysql.com/28666))

   * For debug builds, `ALTER TABLE' could trigger an assertion failure
     due to occurrence of a deadlock when committing changes.
     (Bug#28652 (http://bugs.mysql.com/28652))

   * Attempting to create an index on a `BIT' column failed after
     modifying the column.  (Bug#28631 (http://bugs.mysql.com/28631))

   * After an upgrade, the names of stored routines referenced by views
     were no longer displayed by `SHOW CREATE VIEW'.  (Bug#28605
     (http://bugs.mysql.com/28605)) This regression was introduced by
     Bug#23491 (http://bugs.mysql.com/23491)

   * Conversion of U+00A5 YEN SIGN and U+203E OVERLINE from `ucs2' to
     `ujis' produced incorrect results.  (Bug#28600
     (http://bugs.mysql.com/28600))

   * Killing from one connection a long-running `EXPLAIN QUERY' started
     from another connection caused `mysqld' to crash.  (Bug#28598
     (http://bugs.mysql.com/28598))

   * `SHOW GLOBAL VARIABLES' repeated some variable names.  (Bug#28580
     (http://bugs.mysql.com/28580))

   * When one thread attempts to lock two (or more) tables and another
     thread executes a statement that aborts these locks (such as
     `REPAIR TABLE', `OPTIMIZE TABLE', or `CHECK TABLE'), the thread
     might get a table object with an incorrect lock type in the table
     cache. The result is table corruption or a server crash.
     (Bug#28574 (http://bugs.mysql.com/28574))

   * Outer join queries with `ON' conditions over constant outer tables
     did not return `NULL'-complemented rows when conditions were
     evaluated to `FALSE'.  (Bug#28571 (http://bugs.mysql.com/28571))

   * An update on a multiple-table view with the CHECK OPTION clause
     and a subquery in the WHERE condition could cause an assertion
     failure.  (Bug#28561 (http://bugs.mysql.com/28561))

   * Calling the `UpdateXML()' function using invalid XPath syntax
     caused memory corruption possibly leading to a crash of the server.
     (Bug#28558 (http://bugs.mysql.com/28558))

   * `PURGE MASTER LOGS BEFORE (SUBQUERY)' caused a server crash.
     Subqueries are forbidden in the `BEFORE' clause now.  (Bug#28553
     (http://bugs.mysql.com/28553))

   * `mysqldump' calculated the required memory for a hex-blob string
     incorrectly causing a buffer overrun. This in turn caused
     `mysqldump' to crash silently and produce incomplete output.
     (Bug#28522 (http://bugs.mysql.com/28522))

   * When upgrading from MySQL 5.1.17 to 5.1.18, `mysql_upgrade' and
     `mysql_fix_privilege_tables' did not upgrade the system tables
     relating to the Event Scheduler correctly.  (Bug#28521
     (http://bugs.mysql.com/28521))

   * Passing a `DECIMAL' value as a parameter of a statement prepared
     with `PREPARE' resulted in an error.  (Bug#28509
     (http://bugs.mysql.com/28509))

   * *Note `mysql_affected_rows()': mysql-affected-rows. could return
     an incorrect result for `INSERT ... ON DUPLICATE KEY UPDATE' if
     the `CLIENT_FOUND_ROWS' flag was set.  (Bug#28505
     (http://bugs.mysql.com/28505))

   * A query that grouped by the result of an expression returned a
     different result when the expression was assigned to a user
     variable.  (Bug#28494 (http://bugs.mysql.com/28494))

   * Subselects returning `LONG' values in MySQL versions later than
     5.0.24a returned `LONGLONG' prior to this. The previous behavior
     was restored.  (Bug#28492 (http://bugs.mysql.com/28492)) This
     regression was introduced by Bug#19714
     (http://bugs.mysql.com/19714)

   * Performing `ALTER TABLE ... ADD PARTITION' or `ALTER TABLE DROP
     PARTITION' could result in inconsistent data, or cause the server
     to crash, if done concurrently with other accesses to the table.
     (Bug#28477 (http://bugs.mysql.com/28477), Bug#28488
     (http://bugs.mysql.com/28488))

   * Forcing the use of an index on a `SELECT' query when the index had
     been disabled would raise an error without running the query. The
     query now executes, with a warning generated noting that the use
     of a disabled index has been ignored.  (Bug#28476
     (http://bugs.mysql.com/28476))

   * The result of executing of a prepared statement created with
     `PREPARE s FROM "SELECT 1 LIMIT ?"' was not replicated correctly.
     (Bug#28464 (http://bugs.mysql.com/28464))

   * The query `SELECT '2007-01-01' + INTERVAL COLUMN_NAME DAY FROM
     TABLE_NAME' caused `mysqld' to fail.  (Bug#28450
     (http://bugs.mysql.com/28450))

   * A server crash could happen under rare conditions such that a
     temporary table outgrew heap memory reserved for it and the
     remaining disk space was not big enough to store the table as a
     `MyISAM' table.  (Bug#28449 (http://bugs.mysql.com/28449))

   * Using `ALTER TABLE' to move columns resulted only in the columns
     being renamed. The table contents were not changed.  (Bug#28427
     (http://bugs.mysql.com/28427))

   * The test case for `mysqldump' failed with `bin-log' disabled.
     (Bug#28372 (http://bugs.mysql.com/28372))

   * Attempting to `LOAD_FILE' from an empty floppy drive under
     Windows, caused the server to hang. For example, if you opened a
     connection to the server and then issued the command `SELECT
     LOAD_FILE('a:test');', with no floppy in the drive, the server was
     inaccessible until the modal pop-up dialog box was dismissed.
     (Bug#28366 (http://bugs.mysql.com/28366))

   * `mysqltest' used a too-large stack size on PPC/Debian Linux,
     causing thread-creation failure for tests that use many threads.
     (Bug#28333 (http://bugs.mysql.com/28333))

   * When using a `MEMORY' table on Mac OS X, dropping a table and than
     creating a table with the same name could cause the information of
     the deleted table to remain accessible, leading to index errors.
     (Bug#28309 (http://bugs.mysql.com/28309))

   * The `IS_UPDATABLE' column in the `INFORMATION_SCHEMA.VIEWS' table
     was not always set correctly.  (Bug#28266
     (http://bugs.mysql.com/28266))

   * For `CAST()' of a `NULL' value with type `DECIMAL', the return
     value was incorrectly initialized, producing a runtime error for
     binaries built using Visual C++ 2005.  (Bug#28250
     (http://bugs.mysql.com/28250))

   * Recreating a view that already exists on the master would cause a
     replicating slave to terminate replication with a 'different error
     message on slave and master' error.  (Bug#28244
     (http://bugs.mysql.com/28244))

   * When the query cache was fully used, issuing `RENAME DATABASE' or
     `RENAME SCHEMA' could cause the server to hang, with 100% CPU
     usage.  (Bug#28211 (http://bugs.mysql.com/28211))

   * The `Bytes_received' and `Bytes_sent' status variables could hold
     only 32-bit values (not 64-bit values) on some platforms.
     (Bug#28149 (http://bugs.mysql.com/28149))

   * Some valid identifiers were not parsed correctly.  (Bug#28127
     (http://bugs.mysql.com/28127))

   * Storing a large number into a `FLOAT' or `DOUBLE' column with a
     fixed length could result in incorrect truncation of the number if
     the column's length was greater than 31.  (Bug#28121
     (http://bugs.mysql.com/28121))

   * Sending debugging information from a dump of the Event Scheduler
     to `COM_DEBUG' could cause the server to crash.  (Bug#28075
     (http://bugs.mysql.com/28075))

   * The `PARTITION_COMMENT' column of the
     `INFORMATION_SCHEMA.PARTITIONS' table had the wrong default value.
     (Bug#28007 (http://bugs.mysql.com/28007))

   * `DECIMAL' values beginning with nine `9' digits could be
     incorrectly rounded.  (Bug#27984 (http://bugs.mysql.com/27984))

   * For attempts to open a non-existent table, the server should
     report `ER_NO_SUCH_TABLE' but sometimes reported
     `ER_TABLE_NOT_LOCKED'.  (Bug#27907 (http://bugs.mysql.com/27907))

   * Following an invalid call to `UpdateXML()', calling the function
     again (even if valid) crashed the server.  (Bug#27898
     (http://bugs.mysql.com/27898))

   * A stored program that uses a variable name containing multibyte
     characters could fail to execute.  (Bug#27876
     (http://bugs.mysql.com/27876))

   * The server made strong assumptions about the structure of the
     `general_log' and `slow_log' log tables: It supported only the
     table structure defined in the `mysql' database creation scripts.
     The server also allowed limited `ALTER TABLE' operations on the
     log tables, but adding an `AUTO_INCREMENT' column did not properly
     initialize the column, and subsequent inserts into the table could
     fail to generate correct sequence numbers. Now an `ALTER TABLE'
     statement that adds an `AUTO_INCREMENT' column populates the column
     correctly. In addition, when the server writes a log table row, it
     will set columns not present in the original table structure to
     their default values.  (Bug#27857 (http://bugs.mysql.com/27857))

   * `ON' conditions from `JOIN' expressions were ignored when checking
     the `CHECK OPTION' clause while updating a multiple-table view
     that included such a clause.  (Bug#27827
     (http://bugs.mysql.com/27827))

   * On some systems, `udf_example.c' returned an incorrect result
     length. Also on some systems, `mysql-test-run.pl' could not find
     the shared object built from `udf_example.c'.  (Bug#27741
     (http://bugs.mysql.com/27741))

   * The modification of a table by a partially completed multi-column
     update was not recorded in the binlog, rather than being marked by
     an event and a corresponding error code.  (Bug#27716
     (http://bugs.mysql.com/27716))

   * `SHOW ENGINES' and queries on `INFORMATION_SCHEMA.ENGINES' did not
     use the same values for representing the same storage engine
     states.  (Bug#27684 (http://bugs.mysql.com/27684))

   * `HASH' indexes on `VARCHAR' columns with binary collations did not
     ignore trailing spaces from strings before comparisons. This could
     result in duplicate records being successfully inserted into a
     `MEMORY' table with unique key constraints. A consequence was that
     internal `MEMORY' tables used for `GROUP BY' calculation contained
     duplicate rows that resulted in duplicate-key errors when
     converting those temporary tables to `MyISAM', and that error was
     incorrectly reported as a `table is full' error.  (Bug#27643
     (http://bugs.mysql.com/27643))

   * An error occurred trying to connect to `mysqld-debug.exe'.
     (Bug#27597 (http://bugs.mysql.com/27597))

   * A stack overrun could occur when storing `DATETIME' values using
     repeated prepared statements.  (Bug#27592
     (http://bugs.mysql.com/27592))

   * If a stored function or trigger was killed, it aborted but no
     error was thrown, allowing the calling statement to continue
     without noticing the problem. This could lead to incorrect results.
     (Bug#27563 (http://bugs.mysql.com/27563))

   * When `ALTER TABLE' was used to add a new `DATE' column with no
     explicit default value, `'0000-00-00'' was used as the default
     even if the SQL mode included the `NO_ZERO_DATE' mode to prohibit
     that value. A similar problem occurred for `DATETIME' columns.
     (Bug#27507 (http://bugs.mysql.com/27507))

   * `ALTER TABLE ... ENABLE KEYS' could cause `mysqld' to crash when
     executed on a table containing on a `MyISAM' table containing
     billions of rows.  (Bug#27029 (http://bugs.mysql.com/27029))

   * Binary logging of prepared statements could produce syntactically
     incorrect queries in the binary log, replacing some parameters
     with variable names rather than variable values.  This could lead
     to incorrect results on replication slaves.  (Bug#26842
     (http://bugs.mysql.com/26842), Bug#12826
     (http://bugs.mysql.com/12826))

   * Binary content `0x00' in a `BLOB' column sometimes became `0x5C
     0x00' following a dump and reload, which could cause problems with
     data using multi-byte character sets such as `GBK' (Chinese). This
     was due to a problem with `SELECT INTO OUTFILE' whereby `LOAD
     DATA' later incorrectly interpreted `0x5C' as the second byte of a
     multi-byte sequence rather than as the `SOLIDUS' (`\') character,
     used by MySQL as the escape character.  (Bug#26711
     (http://bugs.mysql.com/26711))

   * Connections from one `mysqld' server to another failed on Mac OS
     X, affecting replication and `FEDERATED' tables.  (Bug#26664
     (http://bugs.mysql.com/26664)) See also Bug#29083
     (http://bugs.mysql.com/29083)

   * The server crashed when attempting to open a table having a
     `#mysql50#' prefix in the database or table name. The server now
     will not open such tables. (This prefix is reserved by
     `mysql_upgrade' for accessing 5.0 tables that have names not yet
     encoded for 5.1.)  (Bug#26402 (http://bugs.mysql.com/26402))

   * A `FLUSH TABLES WITH READ LOCK' statement followed by a `FLUSH
     LOGS' statement caused a deadlock if the general log or the slow
     query log was enabled.  (Bug#26380 (http://bugs.mysql.com/26380))

   * The query `SELECT /*2*/ user, host, db, info FROM
     INFORMATION_SCHEMA.PROCESSLIST WHERE (command!='Daemon' ||
     user='event_scheduler') AND (info IS NULL OR info NOT LIKE
     '%processlist%') ORDER BY INFO' yielded inconsistent results.
     (Bug#26338 (http://bugs.mysql.com/26338))

   * For a given user variable `@v', the statements `SELECT @v' and
     `CREATE TABLE ... AS SELECT @v' did not return the same data type.
     (Bug#26277 (http://bugs.mysql.com/26277))

   * Statements within triggers ignored the value of the
     `low_priority_updates' system variable.  (Bug#26162
     (http://bugs.mysql.com/26162)) See also Bug#29963
     (http://bugs.mysql.com/29963)

   * The embedded server library displayed error messages at startup if
     the `mysql.plugin' table was not present.  This no longer occurs.
     (Bug#25800 (http://bugs.mysql.com/25800))

   * On Windows, an application that called *Note
     `mysql_thread_init()': mysql-thread-init.  but forgot to call
     *Note `mysql_thread_end()': mysql-thread-end.  would get this
     error: `Error in my_thread_global_end()'.  (Bug#25621
     (http://bugs.mysql.com/25621))

   * Embedded `/* ... */' comments were handled incorrectly within the
     definitions of stored programs and views, resulting in malformed
     definitions (the trailing `*/' was stripped). This also affected
     binary log contents.  (Bug#25411 (http://bugs.mysql.com/25411),
     Bug#26302 (http://bugs.mysql.com/26302))

   * Due to a race condition, executing `FLUSH PRIVILEGES' in one
     thread could cause brief table unavailability in other threads.
     (Bug#24988 (http://bugs.mysql.com/24988))

   * In `SHOW SLAVE STATUS' output, `Last_Errno' and `Last_Error' were
     not set after `master_retry_count' errors had occurred. To provide
     additional information, the statement now displays four additional
     columns:

        * `Last_IO_Errno': The number of the last error that caused the
          I/O thread to stop

        * `Last_IO_Error': A description of the last error that caused
          the I/O thread to stop

        * `Last_SQL_Errno': The number of the last error that caused
          the SQL thread to stop

        * `Last_SQL_Error': A description of the last error that caused
          the SQL thread to stop

     Also, `Last_Errno' and `Last_Error' now are aliases for
     `Last_SQL_Errno' and `Last_SQL_Error'.  (Bug#24954
     (http://bugs.mysql.com/24954))

   * A too-long `shared-memory-base-name' value could cause a buffer
     overflow and crash the server or clients.  (Bug#24924
     (http://bugs.mysql.com/24924))

   * When `mysqld' was run as a Windows service, shared memory objects
     were not created in the global namespace and could not be used by
     clients to connect.  (Bug#24731 (http://bugs.mysql.com/24731))

   * On some Linux distributions where LinuxThreads and NPTL `glibc'
     versions both are available, statically built binaries can crash
     because the linker defaults to LinuxThreads when linking
     statically, but calls to external libraries (such as `libnss') are
     resolved to NPTL versions. This cannot be worked around in the
     code, so instead if a crash occurs on such a binary/OS
     combination, print an error message that provides advice about how
     to fix the problem.  (Bug#24611 (http://bugs.mysql.com/24611))

   * A number of `SHOW' statements caused `mysqld' to crash on recent
     versions of Solaris. This issue is believed to be present only in
     MySQL 5.1.12 and later.  (Bug#23810 (http://bugs.mysql.com/23810))

   * The server deducted some bytes from the `key_cache_block_size'
     option value and reduced it to the next lower 512 byte boundary.
     The resulting block size was not a power of two. Setting the
     `key_cache_block_size' system variable to a value that is not a
     power of two resulted in `MyISAM' table corruption.  (Bug#23068
     (http://bugs.mysql.com/23068), Bug#28478
     (http://bugs.mysql.com/28478), Bug#25853
     (http://bugs.mysql.com/25853))

   * Conversion errors could occur when constructing the condition for
     an `IN' predicate. The predicate was treated as if the affected
     column contains `NULL', but if the `IN' predicate is inside `NOT',
     incorrect results could be returned.  (Bug#22855
     (http://bugs.mysql.com/22855))

   * When using transactions and replication, shutting down the master
     in the middle of a transaction would cause all slaves to stop
     replicating.  (Bug#22725 (http://bugs.mysql.com/22725))

   * Linux binaries were unable to dump core after executing a
     `setuid()' call.  (Bug#21723 (http://bugs.mysql.com/21723))

   * Stack overflow caused server crashes.  (Bug#21476
     (http://bugs.mysql.com/21476))

   * Using `CREATE TABLE LIKE ...' would raise an assertion when
     replicated to a slave.  (Bug#18950 (http://bugs.mysql.com/18950))

   * The server was ignoring the return value of the `parse()' function
     for full-text parser plugins.  (Bug#18839
     (http://bugs.mysql.com/18839))

   * Granting access privileges to an individual table where the
     database or table name contained an underscore would fail.
     (Bug#18660 (http://bugs.mysql.com/18660))

   * The `-lmtmalloc' library was removed from the output of
     `mysql_config' on Solaris, as it caused problems when building
     `DBD::mysql' (and possibly other applications) on that platform
     that tried to use `dlopen()' to access the client library.
     (Bug#18322 (http://bugs.mysql.com/18322))

   * The `check-cpu' script failed to detect AMD64 Turion processors
     correctly.  (Bug#17707 (http://bugs.mysql.com/17707))

   * When using `mysqlbinlog' with `--read-from-remote-server' to load
     the data direct from a remote MySQL server would cause a core dump
     when dumping certain binary log events.  (Bug#17654
     (http://bugs.mysql.com/17654))

   * Trying to shut down the server following a failed `LOAD DATA
     INFILE' caused `mysqld' to crash.  (Bug#17233
     (http://bugs.mysql.com/17233))

   * The omission of leading zeros in dates could lead to erroneous
     results when these were compared with the output of certain date
     and time functions.  (Bug#16377 (http://bugs.mysql.com/16377))

   * Using up-arrow for command-line recall in `mysql' could cause a
     segmentation fault.  (Bug#10218 (http://bugs.mysql.com/10218))

   * The result for `CAST()' when casting a value to `UNSIGNED' was
     limited to the maximum signed `BIGINT' value
     (9223372036854775808), rather than the maximum unsigned value
     (18446744073709551615).  (Bug#8663 (http://bugs.mysql.com/8663))

   * The internal functions for table preparation, creation, and
     alteration were not re-execution friendly, causing problems in
     code that: repeatedly altered a table; repeatedly created and
     dropped a table; opened and closed a cursor on a table, altered
     the table, and then reopened the cursor; used `ALTER TABLE' to
     change a table's current `AUTO_INCREMENT' value; created indexes on
     `utf8' columns.

     Re-execution of `CREATE DATABASE', `CREATE TABLE', and `ALTER
     TABLE' statements in stored routines or as prepared statements
     also caused incorrect results or crashes.  (Bug#4968
     (http://bugs.mysql.com/4968), Bug#6895
     (http://bugs.mysql.com/6895), Bug#19182
     (http://bugs.mysql.com/19182), Bug#19733
     (http://bugs.mysql.com/19733), Bug#22060
     (http://bugs.mysql.com/22060), Bug#24879
     (http://bugs.mysql.com/24879))

   * `Last_IO_Error': A description of the last error that caused the
     I/O thread to stop

   * `Last_IO_Errno': The number of the last error that caused the I/O
     thread to stop

   * `Last_SQL_Error': A description of the last error that caused the
     SQL thread to stop

   * `Last_SQL_Errno': The number of the last error that caused the SQL
     thread to stop


File: manual.info,  Node: news-5-1-19,  Next: news-5-1-18,  Prev: news-5-1-20,  Up: news-5-1-x

C.1.11 Changes in MySQL 5.1.19 (25 May 2007)
--------------------------------------------

This is a new Beta development release, fixing recently discovered bugs.

*Note*:

This Beta release, as any other pre-production release, should not be
installed on _production_ level systems or systems with critical data.
It is good practice to back up your data before installing any new
version of software.  Although MySQL has worked very hard to ensure a
high level of quality, protect your data by making a backup as you
would for any software beta release. Please refer to our bug database at
`http://bugs.mysql.com/' for more details about the individual bugs
fixed in this version.

This section documents all changes and bug fixes that have been applied
since the last official MySQL release. If you would like to receive
more fine-grained and personalized _update alerts_ about fixes that are
relevant to the version and features you use, please consider
subscribing to _MySQL Enterprise_ (a commercial MySQL offering). For
more details please see `http://www.mysql.com/products/enterprise'.

Functionality added or changed:

   * *Incompatible Change*: `INSERT DELAYED' is now downgraded to a
     normal `INSERT' if the statement uses functions that access tables
     or triggers, or that is called from a function or a trigger.

     This was done to resolve the following interrelated issues:

        * The server could abort or deadlock for `INSERT DELAYED'
          statements for which another insert was performed implicitly
          (for example, via a stored function that inserted a row).

        * A trigger using an `INSERT DELAYED' caused the error `INSERT
          DELAYED can't be used with table ... because it is locked
          with LOCK TABLES' although the target table was not actually
          locked.

        * `INSERT DELAYED' into a table with a `BEFORE INSERT' or `AFTER
          INSERT' trigger gave an incorrect `NEW' pseudocolumn value
          and caused the server to deadlock or abort.

     (Bug#21483 (http://bugs.mysql.com/21483)) See also Bug#20497
     (http://bugs.mysql.com/20497), Bug#21714
     (http://bugs.mysql.com/21714)

   * *MySQL Cluster*: Formerly, restoring a cluster backup made on a
     MySQL 5.0 Cluster to a 5.1 cluster using a 5.1 version of
     `ndb_restore' did not resize `VARCHAR' columns as might be
     expected; now, the default behavior of `ndb_restore' in such cases
     is to resize the `VARCHAR' columns. This changed default behavior
     can be overridden using the `--no-upgrade' (or `-u') option when
     invoking `ndb_restore'.  (Bug#22240 (http://bugs.mysql.com/22240))

   * The `BLACKHOLE' storage engine now supports `INSERT DELAYED'.
     Previously, `INSERT DELAYED' statements for `BLACKHOLE' tables
     were not supported, and caused the server to crash.  (Bug#27998
     (http://bugs.mysql.com/27998))

   * A new status variable, `Com_call_procedure', indicates the number
     of calls to stored procedures.  (Bug#27994
     (http://bugs.mysql.com/27994))

   * The `BLACKHOLE' storage engine now supports `LOCK TABLES' and
     `UNLOCK TABLES'.  (Bug#26241 (http://bugs.mysql.com/26241))

   * `GLOBAL_STATUS'

   * `GLOBAL_VARIABLES'

   * `SESSION_VARIABLES'

   * The data type used for the `VARIABLE_VALUE' column of the
     following INFORMATION_SCHEMA tables has been changed to `VARCHAR':

        * `GLOBAL_STATUS'

        * `SESSION_STATUS'

        * `GLOBAL_VARIABLES'

        * `SESSION_VARIABLES'

     For more information, see *Note status-table::, *Note
     variables-table::.

     See also Bug#26994 (http://bugs.mysql.com/26994)

   * `SESSION_STATUS'

Bugs fixed:

   * *Security Fix*: UDFs are supposed to be loadable only from the
     plugin directory, but this restriction was not being enforced.
     (Bug#28341 (http://bugs.mysql.com/28341))

   * *Security Fix*: Use of a view could allow a user to gain update
     privileges for tables in other databases.  (Bug#27878
     (http://bugs.mysql.com/27878), CVE-2007-3782
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-3782))

   * *MySQL Cluster*: When an API node sent more than 1024 signals in a
     single batch, `NDB' would process only the first 1024 of these,
     and then hang.  (Bug#28443 (http://bugs.mysql.com/28443))

   * *MySQL Cluster*: A delay in obtaining `AUTO_INCREMENT' IDs could
     lead to excess temporary errors.  (Bug#28410
     (http://bugs.mysql.com/28410))

   * *MySQL Cluster*: Local checkpoint files relating to dropped `NDB'
     tables were not removed.  (Bug#28348 (http://bugs.mysql.com/28348))

   * *MySQL Cluster*: Multiple operations involving deletes followed by
     reads were not handled correctly.

     *Note*:

     This issue could also affect MySQL Cluster Replication.

     (Bug#28276 (http://bugs.mysql.com/28276))

   * *MySQL Cluster*: Repeated insertion of data generated by
     `mysqldump' into `NDB' tables could eventually lead to failure of
     the cluster.  (Bug#27437 (http://bugs.mysql.com/27437))

   * *MySQL Cluster*: Restarting a data node caused SQL nodes to log
     repeatedly and unnecessarily the status of the event buffer.

     (This issue was known to occur in MySQL 5.1.16 and later only.)
     (Bug#27292 (http://bugs.mysql.com/27292))

   * *MySQL Cluster*: `ndb_mgmd' failed silently when the cluster
     configuration file contained invalid `[tcp]' entries.  (Bug#27207
     (http://bugs.mysql.com/27207))

   * *MySQL Cluster*: `ndb_connectstring' did not appear in the output
     of `SHOW VARIABLES'.  (Bug#26675 (http://bugs.mysql.com/26675))

   * *MySQL Cluster*: A failure to release internal resources following
     an error could lead to problems with single user mode.  (Bug#25818
     (http://bugs.mysql.com/25818))

   * *MySQL Cluster*: DDL operations were not supported on a partially
     started cluster.  (Bug#24631 (http://bugs.mysql.com/24631))

   * *Disk Data*: Extremely large inserts into Disk Data tables could
     lead to data node failure in some circumstances.  (Bug#27942
     (http://bugs.mysql.com/27942))

   * *Cluster API*: In a multi-operation transaction, a delete
     operation followed by the insertion of an implicit `NULL' failed to
     overwrite an existing value.  (Bug#20535
     (http://bugs.mysql.com/20535))

   * Some `ALTER TABLE' statements that worked in MySQL 5.0 did not
     work in 5.1.  (Bug#28415 (http://bugs.mysql.com/28415))

   * `mysql_upgrade' failed if certain SQL modes were set. Now it sets
     the mode itself to avoid this problem.  (Bug#28401
     (http://bugs.mysql.com/28401))

   * A query with a `NOT IN' subquery predicate could cause a crash
     when the left operand of the predicate evaluated to `NULL'.
     (Bug#28375 (http://bugs.mysql.com/28375))

   * A buffer overflow could occur when using `DECIMAL' columns on
     Windows operating systems.  (Bug#28361
     (http://bugs.mysql.com/28361))

   * `libmysql.dll' could not be dynamically loaded on Windows.
     (Bug#28358 (http://bugs.mysql.com/28358))

   * Grouping queries with correlated subqueries in `WHERE' conditions
     could produce incorrect results.  (Bug#28337
     (http://bugs.mysql.com/28337))

   * `EXPLAIN' for a query on an empty table immediately after its
     creation could result in a server crash.  (Bug#28272
     (http://bugs.mysql.com/28272))

   * Comparing a `DATETIME' column value with a user variable yielded
     incorrect results.  (Bug#28261 (http://bugs.mysql.com/28261))

   * Portability problems caused by use of `isinf()' were corrected.
     (Bug#28240 (http://bugs.mysql.com/28240))

   * When dumping procedures, `mysqldump `--compact' ' generated output
     that restored the session variable `SQL_MODE' without first
     capturing it. When dumping routines, `mysqldump `--compact' '
     neither set nor retrieved the value of `SQL_MODE'.  (Bug#28223
     (http://bugs.mysql.com/28223))

   * Comparison of the string value of a date showed as unequal to
     `CURTIME()'. Similar behavior was exhibited for `DATETIME' values.
     (Bug#28208 (http://bugs.mysql.com/28208))

   * For `InnoDB', in some rare cases the optimizer preferred a more
     expensive `ref' access to a less expensive range access.
     (Bug#28189 (http://bugs.mysql.com/28189))

   * Comparisons of `DATE' or `DATETIME' values for the `IN()' function
     could yield incorrect results.  (Bug#28133
     (http://bugs.mysql.com/28133))

   * It was not possible to use the value `-9223372036854775808' (that
     is, `-MAXVALUE + 1') when specifying a `LIST' partition.
     (Bug#28005 (http://bugs.mysql.com/28005))

   * The server could hang for `INSERT IGNORE ... ON DUPLICATE KEY
     UPDATE' if an update failed.  (Bug#28000
     (http://bugs.mysql.com/28000))

   * `CAST()' to `DECIMAL' did not check for overflow.  (Bug#27957
     (http://bugs.mysql.com/27957))

   * The second execution of a prepared statement from a `UNION' query
     with `ORDER BY RAND()' caused the server to crash. This problem
     could also occur when invoking a stored procedure containing such a
     query.  (Bug#27937 (http://bugs.mysql.com/27937))

   * Views ignored precision for `CAST()' operations.  (Bug#27921
     (http://bugs.mysql.com/27921))

   * Changes to some system variables should invalidate statements in
     the query cache, but invalidation did not happen.  (Bug#27792
     (http://bugs.mysql.com/27792))

   * `LOAD DATA' did not use `CURRENT_TIMESTAMP' as the default value
     for a `TIMESTAMP' column for which no value was provided.
     (Bug#27670 (http://bugs.mysql.com/27670))

   * Selecting `MIN()' on an indexed column that contained only `NULL'
     values caused `NULL' to be returned for other result columns.
     (Bug#27573 (http://bugs.mysql.com/27573))

   * Using a `TEXT' local variable in a stored routine in an expression
     such as `SET VAR = SUBSTRING(VAR, 3)' produced an incorrect result.
     (Bug#27415 (http://bugs.mysql.com/27415))

   * The error message for error number `137' did not report which
     database/table combination reported the problem.  (Bug#27173
     (http://bugs.mysql.com/27173))

   * A large filesort could result in a division by zero error and a
     server crash.  (Bug#27119 (http://bugs.mysql.com/27119))

   * Some `InnoDB' variables were missing from the output of `mysqld
     --verbose --help'.  (Bug#26987 (http://bugs.mysql.com/26987))

   * Flow control optimization in stored routines could cause exception
     handlers to never return or execute incorrect logic.  (Bug#26977
     (http://bugs.mysql.com/26977))

   * Some test suite files were missing from some MySQL-test packages.
     (Bug#26609 (http://bugs.mysql.com/26609))

   * Running `CHECK TABLE' concurrently with a `SELECT', `INSERT' or
     other statement on Windows could corrupt a MyISAM table.
     (Bug#25712 (http://bugs.mysql.com/25712))

   * Concurrent execution of `CREATE TABLE ...  SELECT' and other
     statements involving the target table suffered from various race
     conditions, some of which might have led to deadlocks.  (Bug#24738
     (http://bugs.mysql.com/24738))

   * An attempt to execute `CREATE TABLE ... SELECT' when a temporary
     table with the same name already existed led to the insertion of
     data into the temporary table and creation of an empty
     non-temporary table.  (Bug#24508 (http://bugs.mysql.com/24508))

   * A statement of the form `CREATE TABLE IF NOT EXISTS t1 SELECT f1()
     AS i' failed with a deadlock error if the stored function `f1()'
     referred to a table with the same name as the to-be-created table.
     Now it correctly produces a message that the table already exists.
     (Bug#22427 (http://bugs.mysql.com/22427))

   * Quoted labels in stored routines were mishandled, rendering the
     routines unusable.  (Bug#21513 (http://bugs.mysql.com/21513))

   * `CURDATE()' is less than `NOW()', either when comparing `CURDATE()'
     directly (`CURDATE() < NOW()' is true) or when casting `CURDATE()'
     to `DATE' (`CAST(CURDATE() AS DATE) < NOW()' is true). However,
     storing `CURDATE()' in a `DATE' column and comparing ` COL_NAME <
     NOW()' incorrectly yielded false. This is fixed by comparing a
     `DATE' column as `DATETIME' for comparisons to a `DATETIME'
     constant.  (Bug#21103 (http://bugs.mysql.com/21103))

   * `CREATE TABLE IF NOT EXISTS ... SELECT' caused a server crash if
     the target table already existed and had a `BEFORE INSERT' trigger.
     (Bug#20903 (http://bugs.mysql.com/20903))

   * Deadlock occurred for attempts to execute `CREATE TABLE IF NOT
     EXISTS ... SELECT' when `LOCK TABLES' had been used to acquire a
     read lock on the target table.  (Bug#20662
     (http://bugs.mysql.com/20662), Bug#15522
     (http://bugs.mysql.com/15522))

   * For dates with 4-digit year parts less than 200, an incorrect
     implicit conversion to add a century was applied for date
     arithmetic performed with `DATE_ADD()', `DATE_SUB()', `+
     INTERVAL', and `- INTERVAL'. (For example, `DATE_ADD('0050-01-01
     00:00:00', INTERVAL 0 SECOND)' became `'2050-01-01 00:00:00''.)
     (Bug#18997 (http://bugs.mysql.com/18997))

   * Changing the size of a key buffer that is under heavy use could
     cause a server crash. The fix partially removes the limitation
     that `LOAD INDEX INTO CACHE' fails unless all indexes in a table
     have the same block size. Now the statement fails only if `IGNORE
     LEAVES' is specified.  (Bug#17332 (http://bugs.mysql.com/17332))


File: manual.info,  Node: news-5-1-18,  Next: news-5-1-17,  Prev: news-5-1-19,  Up: news-5-1-x

C.1.12 Changes in MySQL 5.1.18 (08 May 2007)
--------------------------------------------

This is a new Beta development release, fixing recently discovered bugs.

*Note*:

This Beta release, as any other pre-production release, should not be
installed on _production_ level systems or systems with critical data.
It is good practice to back up your data before installing any new
version of software.  Although MySQL has worked very hard to ensure a
high level of quality, protect your data by making a backup as you
would for any software beta release. Please refer to our bug database at
`http://bugs.mysql.com/' for more details about the individual bugs
fixed in this version.

This section documents all changes and bug fixes that have been applied
since the last official MySQL release. If you would like to receive
more fine-grained and personalized _update alerts_ about fixes that are
relevant to the version and features you use, please consider
subscribing to _MySQL Enterprise_ (a commercial MySQL offering). For
more details please see `http://www.mysql.com/products/enterprise'.

Functionality added or changed:

   * *Incompatible Change*: *MySQL Cluster*: The internal
     specifications for columns in `NDB' tables has changed to allow
     compatibility with future MySQL Cluster releases that are expected
     to implement online adding and dropping of columns. This change is
     not backward compatible with earlier versions of MySQL Cluster.

     See the related note in *Note
     mysql-cluster-upgrade-downgrade-compatibility::, for important
     information prior to upgrading a MySQL Cluster to MySQL 5.1.18 or
     later from MySQL 5.1.17 or earlier.

     See also Bug#28205 (http://bugs.mysql.com/28205)

   * *Cluster Replication*: *Incompatible Change*: The definition of
     the `mysql.ndb_apply_status' table has changed such that an online
     upgrade is not possible from MySQL 5.1.17 or earlier for a
     replication slave cluster; you must shut down all SQL nodes as
     part of the upgrade procedure. See *Note
     mysql-cluster-upgrade-downgrade-compatibility:: before upgrading
     for details.

     For more information about the changes to `mysql.ndb_apply_status'
     see *Note mysql-cluster-replication-schema::.

   * *Incompatible Change*: Prior to this release, when `DATE' values
     were compared with `DATETIME' values, the time portion of the
     `DATETIME' value was ignored, or the comparison could be performed
     as a string compare. Now a `DATE' value is coerced to the
     `DATETIME' type by adding the time portion as `00:00:00'. To mimic
     the old behavior, use the `CAST()' function to cause the
     comparison operands to be treated as previously. For example:
     `SELECT DATE_COL = CAST(NOW() AS DATE);'.  (Bug#28929
     (http://bugs.mysql.com/28929))

   * *Incompatible Change*: The `INFORMATION_SCHEMA.EVENTS' and
     `mysql.event' tables have been changed to facilitate replication
     of events. When upgrading to MySQL 5.1.18, you must run
     `mysql_upgrade' prior to working with events. Until you have done
     so, any statement relating to the Event Scheduler or these tables
     (including `SHOW EVENTS') will fail with the errors `Expected
     field status at position 12 to have type enum
     ('ENABLED','SLAVESIDE_DISABLED','DISABLED'), found
     enum('ENABLED','DISABLED')' and `Table mysql.event is damaged. Can
     not open'.

     These changes were made as part of fixes for the following bugs:

        * The effects of scheduled events were not replicated (that is,
          binary logging of scheduled events did not work).

        * Effects of scheduled events on a replication master were both
          replicated and executed on the slave, causing double
          execution of events.

        * `CREATE FUNCTION' statements and their effects were not
          replicated correctly.

     For more information, see *Note replication-features-invoked::.
     (Bug#17857 (http://bugs.mysql.com/17857), Bug#16421
     (http://bugs.mysql.com/16421), Bug#20384
     (http://bugs.mysql.com/20384), Bug#17671
     (http://bugs.mysql.com/17671))

   * *Important Change*: When upgrading to MySQL 5.1.18 or later from a
     previous MySQL version and scheduled events have been used, the
     upgrade utilities do not accomodate changes in event-related system
     tables. As a workaround, you can dump events before the upgrade,
     then restore them from the dump afterwards. This issue was fixed
     in MySQL 5.1.20.

     See also Bug#28521 (http://bugs.mysql.com/28521)

   * *MySQL Cluster*: The behavior of the `ndb_restore' utility has
     been changed as follows:

        * It is now possible to restore selected databases or tables
          using `ndb_restore'.

        * Several options have been added for use with `ndb_restore
          `--print_data' ' to facilitate the creation of structured data
          dump files. These options can be used to make dumps made
          using `ndb_restore' more like those produced by `mysqldump'.

     For details of these changes, see *Note mysql-cluster-restore::.
     (Bug#26899 (http://bugs.mysql.com/26899), Bug#26900
     (http://bugs.mysql.com/26900))

   * *MySQL Cluster*: The following changes were made in the
     `ndb_size.pl' utility:

        * When `ndb_size.pl' calculates a value for a given
          configuration parameter that is less than the default value,
          it now suggests the default value instead.

        * The dependency on `HTML::Template' was removed, with the
          result that the file `ndb_size.tmpl' is no longer needed or
          included.

     (Bug#24227 (http://bugs.mysql.com/24227), Bug#24228
     (http://bugs.mysql.com/24228))

   * *Cluster Replication*: Some circular replication setups are now
     supported for MySQL Cluster. See *Note
     mysql-cluster-replication-issues::, for detailed information.
     (Bug#17095 (http://bugs.mysql.com/17095), Bug#25688
     (http://bugs.mysql.com/25688))

   * *Cluster API*: The MGM API now supports explicit setting of
     network timeouts using the `ndb_mgm_set_timeout()' function. A
     utility function `ndb_mgm_number_of_mgmd_in_connect_string()' is
     also implemented to facilitate calculation of timeouts based on
     the number of management servers in the cluster.

     For more information, see `ndb_mgm_set_timeout()'
     (http://dev.mysql.com/doc/ndbapi/en/ndb-mgm-set-timeout.html), and
     `ndb_mgm_number_of_mgmd_in_connect_string()'
     (http://dev.mysql.com/doc/ndbapi/en/ndb-mgm-number-of-mgmd-in-connect-string.html).

   * `mysqld_multi' now understands the `--no-defaults',
     `--defaults-file', and `--defaults-extra-file' options. The
     `--config-file' option is deprecated; if given, it is treated like
     `--defaults-extra-file'.  (Bug#27390 (http://bugs.mysql.com/27390))

   * If a set function S with an outer reference ` S(OUTER_REF)' cannot
     be aggregated in the outer query against which the outer reference
     has been resolved, MySQL interprets ` S(OUTER_REF)' the same way
     that it would interpret ` S(CONST)'.  However, standard SQL
     requires throwing an error in this situation. An error now is
     thrown for such queries if the `ANSI' SQL mode is enabled.
     (Bug#27348 (http://bugs.mysql.com/27348))

   * Several additional data types are supported for columns in
     `INFORMATION_SCHEMA' tables: `DATE', `TIME', `BLOB', `FLOAT', and
     all integer types.  (Bug#27047 (http://bugs.mysql.com/27047))

   * The output of `mysql `--xml' ' and `mysqldump `--xml' ' now
     includes a valid XML namespace.  (Bug#25946
     (http://bugs.mysql.com/25946))

   * If you use SSL for a client connection, you can tell the client
     not to authenticate the server certificate by specifying neither
     `--ssl-ca' nor `--ssl-capath'. The server still verifies the
     client according to any applicable requirements established via
     `GRANT' statements for the client, and it still uses any
     `--ssl-ca'/`--ssl-capath' values that were passed to server at
     startup time.  (Bug#25309 (http://bugs.mysql.com/25309))

   * Added a `MASTER_SSL_VERIFY_SERVER_CERT' option for the `CHANGE
     MASTER' statement, and a `Master_SSL_Verify_Server_Cert' output
     column to the `SHOW SLAVE STATUS' statement. The option value also
     is written to the `master.info' file.  (Bug#19991
     (http://bugs.mysql.com/19991))

   * The `innodb_log_archive' system variable has been removed. The
     impact of this change should be low because the variable was
     unused, anyway.

   * Added the `--auto-generate-sql-add-auto-increment',
     `--auto-generate-sql-execute-number',
     `--auto-generate-sql-guid-primary',
     `--auto-generate-sql-secondary-indexes',
     `--auto-generate-sql-unique-query-number',
     `--auto-generate-sql-unique-write-number', `--post-query',, and
     `--pre-query', options for `mysqlslap'. Removed the
     `--lock-directory', `--slave', and `--use-threads' options.

   * Added `--write-binlog' option for `mysqlcheck'. This option is
     enabled by default, but can be given as `--skip-write-binlog' to
     cause `ANALYZE TABLE', `OPTIMIZE TABLE', and `REPAIR TABLE'
     statements generated by `mysqlcheck' not to be written to the
     binary log. (Bug#26262 (http://bugs.mysql.com/26262))

   * New command-line options: To alleviate ambiguities in variable
     names, all variables related to plugins can be specified using a
     `plugin' part in the name. For example, every time where we used
     to have `innodb' in the command-line options, you can now write
     `plugin-innodb':

          --skip-plugin-innodb
          --plugin-innodb-buffer-pool-size=#

     Furthermore, this is the preferred syntax. It helps to avoid
     ambiguities when a plugin, say, `wait', has an option called
     `timeout'.  `--wait-timeout' will still set a system variable, but
     `--plugin-wait-timeout' will set the plugin variable. Also, there
     is a new command-line option `--plugin-load' to install or load
     plugins at initialization time without using the `mysql.plugin'
     table.

   * The plugin interface and its handling of system variables was
     changed. Command-line options such as `--skip-innodb' now cause an
     error if `InnoDB' is not built-in or plugin-loaded. You should use
     `--loose-skip-innodb' if you do not want any error even if
     `InnoDB' is not available. The `--loose' prefix modifier should be
     used for all command-line options where you are uncertain whether
     the plugin exists and when you want the operation to proceed even
     if the option is necessarily ignored due to the absence of the
     plugin. (For a desecription of how `--loose' works, see *Note
     command-line-options::.)

   * Storage engine plugins may now be uninstalled at run time.
     However, a plugin is not actually uninstalled until after its
     reference count drops to zero. The `default_storage_engine' system
     variable consumes a reference count, so uninstalling will not
     complete until said reference is removed.

   * The `mysql_create_system_tables' script was removed because
     `mysql_install_db' no longer uses it in MySQL 5.1.

   * Renamed the `old_mode' system variable to `old'.

Bugs fixed:

   * *Security Fix*: The requirement of the `DROP' privilege for
     `RENAME TABLE' was not enforced.  (Bug#27515
     (http://bugs.mysql.com/27515), CVE-2007-2691
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-2691))

   * *Security Fix*: If a stored routine was declared using `SQL
     SECURITY INVOKER', a user who invoked the routine could gain
     privileges.  (Bug#27337 (http://bugs.mysql.com/27337),
     CVE-2007-2692
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-2692))

   * *Security Fix*: A user with only the `ALTER' privilege on a
     partitioned table could obtain information about the table that
     should require the `SELECT' privilege.  (Bug#23675
     (http://bugs.mysql.com/23675), CVE-2007-2693
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-2693))

   * *MySQL Cluster*: The cluster waited 30 seconds instead of 30
     milliseconds before reading table statistics.  (Bug#28093
     (http://bugs.mysql.com/28093))

   * *MySQL Cluster*: Under certain rare circumstances, `ndbd' could
     get caught in an infinite loop when one transaction took a read
     lock and then a second transaction attempted to obtain a write
     lock on the same tuple in the lock queue.  (Bug#28073
     (http://bugs.mysql.com/28073))

   * *MySQL Cluster*: Under some circumstances, a node restart could
     fail to update the Global Checkpoint Index (GCI).  (Bug#28023
     (http://bugs.mysql.com/28023))

   * *MySQL Cluster*: `INSERT IGNORE' wrongly ignored `NULL' values in
     unique indexes.  (Bug#27980 (http://bugs.mysql.com/27980))

   * *MySQL Cluster*: The name of the month `March' was given
     incorrectly in the cluster error log.  (Bug#27926
     (http://bugs.mysql.com/27926))

   * *MySQL Cluster*: `NDB' tables having `MEDIUMINT AUTO_INCREMENT'
     columns were not restored correctly by `ndb_restore', causing
     spurious duplicate key errors. This issue did not affect `TINYINT',
     `INT', or `BIGINT' columns with `AUTO_INCREMENT'.  (Bug#27775
     (http://bugs.mysql.com/27775))

   * *MySQL Cluster*: `NDB' tables with indexes whose names contained
     space characters were not restored correctly by `ndb_restore' (the
     index names were truncated).  (Bug#27758
     (http://bugs.mysql.com/27758))

   * *MySQL Cluster*: An `INSERT' followed by a delete `DELETE' on the
     same `NDB' table caused a memory leak.  (Bug#27756
     (http://bugs.mysql.com/27756)) This regression was introduced by
     Bug#20612 (http://bugs.mysql.com/20612)

   * *MySQL Cluster*: It was not possible to add a unique index to an
     `NDB' table while in single user mode.  (Bug#27710
     (http://bugs.mysql.com/27710))

   * *MySQL Cluster*: Under certain rare circumstances performing a
     `DROP TABLE' or `TRUNCATE' on an `NDB' table could cause a node
     failure or forced cluster shutdown.  (Bug#27581
     (http://bugs.mysql.com/27581))

   * *MySQL Cluster*: Memory usage of a `mysqld' process grew even
     while idle.  (Bug#27560 (http://bugs.mysql.com/27560))

   * *MySQL Cluster*: Using more than 16GB for `DataMemory' caused
     problems with variable-size columns.  (Bug#27512
     (http://bugs.mysql.com/27512))

   * *MySQL Cluster*: A data node failing while another data node was
     restarting could leave the cluster in an inconsistent state. In
     certain rare cases, this could lead to a race condition and the
     eventual forced shutdown of the cluster.  (Bug#27466
     (http://bugs.mysql.com/27466))

   * *MySQL Cluster*: When using the `MemReportFrequency' configuration
     parameter to generate periodic reports of memory usage in the
     cluster log, `DataMemory' usage was not always reported for all
     data nodes.  (Bug#27444 (http://bugs.mysql.com/27444))

   * *MySQL Cluster*: (Replication): An `UPDATE' on the master became a
     `DELETE' on slaves.  (Bug#27378 (http://bugs.mysql.com/27378))

   * *MySQL Cluster*: When trying to create an `NDB' table after the
     server was started with `--ndbcluster' but without
     `--ndb-connectstring', `mysqld' produced a memory allocation error.
     (Bug#27359 (http://bugs.mysql.com/27359))

   * *MySQL Cluster*: Performing a delete followed by an insert during
     a local checkpoint could cause a `Rowid already allocated' error.
     (Bug#27205 (http://bugs.mysql.com/27205))

   * *MySQL Cluster*: In an `NDB' table having a `TIMESTAMP' column
     using `DEFAULT CURRENT_TIMESTAMP', that column would assume a
     random value when another column in the same row was updated.
     (Bug#27127 (http://bugs.mysql.com/27127))

   * *MySQL Cluster*: Error messages displayed when running in single
     user mode were inconsistent.  (Bug#27021
     (http://bugs.mysql.com/27021))

   * *MySQL Cluster*: On Solaris, the value of an `NDB' table column
     declared as `BIT(33)' was always displayed as `0'.  (Bug#26986
     (http://bugs.mysql.com/26986))

   * *MySQL Cluster*: Performing `ALTER TABLE ... ENGINE=MERGE' on an
     `NDB' table caused `mysqld' to crash.  (Bug#26898
     (http://bugs.mysql.com/26898))

   * *MySQL Cluster*: The `NDBCLUSTER' table handler did not set bits
     in null bytes correctly.  (Bug#26591 (http://bugs.mysql.com/26591))

   * *MySQL Cluster*: In some cases, `AFTER UPDATE' and `AFTER DELETE'
     triggers on `NDB' tables that referenced subject table did not see
     the results of operation which caused invocation of the trigger,
     but rather saw the row as it was prior to the update or delete
     operation.

     This was most noticeable when an update operation used a subquery
     to obtain the rows to be updated. An example would be `UPDATE tbl1
     SET col2 = val1 WHERE tbl1.col1 IN (SELECT col3 FROM tbl2 WHERE c4
     = val2)' where there was an `AFTER UPDATE' trigger on table
     `tbl1'. In such cases, the trigger would fail to execute.

     The problem occurred because the actual update or delete
     operations were deferred to be able to perform them later as one
     batch. The fix for this bug solves the problem by disabling this
     optimization for a given update or delete if the table has an
     `AFTER' trigger defined for this operation.  (Bug#26242
     (http://bugs.mysql.com/26242))

   * *MySQL Cluster*: Joins on multiple tables containing `BLOB'
     columns could cause data nodes run out of memory, and to crash
     with the error `NdbObjectIdMap::expand unable to expand'.
     (Bug#26176 (http://bugs.mysql.com/26176))

   * *MySQL Cluster*: `START BACKUP NOWAIT' caused a spurious `Out of
     backup record' error in the management client (`START BACKUP' and
     `START BACKUP WAIT STARTED' performed normally).  (Bug#25446
     (http://bugs.mysql.com/25446))

   * *MySQL Cluster*: Adding of indexes online failed for `NDB' tables
     having `BLOB' or `TEXT' columns.  (Bug#25431
     (http://bugs.mysql.com/25431))

   * *MySQL Cluster*: When a cluster data node suffered a `hard' failure
     (such as a power failure or loss of a network connection) TCP
     sockets to the missing node were maintained indefinitely. Now
     socket-based transporters check for a response and terminate the
     socket if there is no activity on the socket after 2 hours.
     (Bug#24793 (http://bugs.mysql.com/24793))

   * *MySQL Cluster*: The `ndb_resize.pl' utility did not calculate
     memory usage for indexes correctly.  (Bug#24229
     (http://bugs.mysql.com/24229))

   * *MySQL Cluster*: While a data node was stopped, dropping a table
     then creating an index on a different table caused that node to
     fail during restart. This was due to the re-use of the dropped
     table's internal ID for the index without verifying that the index
     now referred to a different database object.  (Bug#21755
     (http://bugs.mysql.com/21755))

   * *MySQL Cluster*: When trying to create tables on an SQL node not
     connected to the cluster, a misleading error message `Table
     'TBL_NAME' already exists' was generated. The error now generated
     is `Could not connect to storage engine'.  (Bug#18676
     (http://bugs.mysql.com/18676))

   * *Replication*: Out-of-memory errors were not reported. Now they
     are written to the error log.  (Bug#26844
     (http://bugs.mysql.com/26844))

   * *Cluster Replication*: *Disk Data*: An issue with replication of
     Disk Data tables could in some cases lead to node failure.
     (Bug#28161 (http://bugs.mysql.com/28161))

   * *Disk Data*: Changes to a Disk Data table made as part of a
     transaction could not be seen by the client performing the changes
     until the transaction had been committed.  (Bug#27757
     (http://bugs.mysql.com/27757))

   * *Disk Data*: When in single user mode, it was possible to create
     log file groups and tablespaces from any SQL node connected to the
     cluster.  (Bug#27712 (http://bugs.mysql.com/27712))

   * *Disk Data*: `CREATE TABLE ... LIKE DISK_DATA_TABLE' created an
     in-memory `NDB' table.  (Bug#25875 (http://bugs.mysql.com/25875))

   * *Disk Data*: When restarting a data node following the creation of
     a large number of Disk Data objects (approximately 200 such
     objects), the cluster could not assign a node ID to the restarting
     node.  (Bug#25741 (http://bugs.mysql.com/25741))

   * *Disk Data*: Creating an excessive number of Disk Data tables
     (1000 or more) could cause data nodes to fail.  (Bug#24951
     (http://bugs.mysql.com/24951))

   * *Disk Data*: Changing a column specification or issuing a
     `TRUNCATE' statement on a Disk Data table caused the table to
     become an in-memory table.

     This fix supersedes an incomplete fix that was made for this issue
     in MySQL 5.1.15.  (Bug#24667 (http://bugs.mysql.com/24667),
     Bug#25296 (http://bugs.mysql.com/25296))

   * *Disk Data*: Setting the value of the `UNDO BUFFER SIZE' to 64K or
     less in a `CREATE LOGFILE GROUP' statement led to failure of
     cluster data nodes.  (Bug#24560 (http://bugs.mysql.com/24560))

   * *Disk Data*: Creating an excessive number of data files for a
     single tablespace caused data nodes to crash.  (Bug#24521
     (http://bugs.mysql.com/24521))

   * *Disk Data*: It was possible to drop the last remaining datafile
     in a tablespace using `ALTER TABLESPACE', even when there was
     still an empty table using the tablespace.

     *Note*:

     The datafile could be not dropped if the table still contained any
     rows, so this bug involved no loss of data.

     (Bug#21699 (http://bugs.mysql.com/21699))

   * *Cluster Replication*: Some queries that updated multiple tables
     were not backed up correctly.  (Bug#27748
     (http://bugs.mysql.com/27748))

   * *Cluster Replication*: It was possible for API nodes to begin
     interacting with the cluster subscription manager before they were
     fully connected to the cluster.  (Bug#27728
     (http://bugs.mysql.com/27728))

   * *Cluster Replication*: Under very high loads, checkpoints could be
     read or written with checkpoint indexes out of order.  (Bug#27651
     (http://bugs.mysql.com/27651))

   * *Cluster Replication*: Trying to replicate a large number of
     frequent updates with a relatively small relay log
     (`max-relay-log-size' set to 1M or less) could cause the slave to
     crash.  (Bug#27529 (http://bugs.mysql.com/27529))

   * *Cluster Replication*: Setting `SQL_LOG_BIN' to zero did not
     disable binary logging.

     This issue affected only the `NDB' storage engine.  (Bug#27076
     (http://bugs.mysql.com/27076))

   * *Cluster Replication*: An SQL node acting as a replication master
     server could be a single point of failure; that is, if it failed,
     the replication slave had no way of knowing this, which could
     result in a mismatch of data between the master and the slave.
     (Bug#21494 (http://bugs.mysql.com/21494))

   * *Cluster API*: For `BLOB' reads on operations with lock mode
     `LM_CommittedRead', the lock mode was not upgraded to `LM_Read'
     before the state of the `BLOB' had already been calculated. The
     `NDB' API methods affected by this problem included the following:

        * `NdbOperation::readTuple()'

        * `NdbScanOperation::readTuples()'

        * `NdbIndexScanOperation::readTuples()'

     (Bug#27320 (http://bugs.mysql.com/27320))

   * *Cluster API*: Using `NdbBlob::writeData()' to write data in the
     middle of an existing blob value (that is, updating the value)
     could overwrite some data past the end of the data to be changed.
     (Bug#27018 (http://bugs.mysql.com/27018))

   * A performance degradation was observed for outer join queries to
     which a not-exists optimization was applied.  (Bug#28188
     (http://bugs.mysql.com/28188))

   * `SELECT * INTO OUTFILE ... FROM INFORMATION_SCHEMA.SCHEMATA'
     failed with an `Access denied' error, even for a user who had the
     `FILE' privilege.  (Bug#28181 (http://bugs.mysql.com/28181))

   * Early `NULL'-filtering optimization did not work for `eq_ref'
     table access.  (Bug#27939 (http://bugs.mysql.com/27939))

   * Non-grouped columns were allowed by `*' in `ONLY_FULL_GROUP_BY'
     SQL mode.  (Bug#27874 (http://bugs.mysql.com/27874))

   * Some equi-joins containing a `WHERE' clause that included a `NOT
     IN' subquery caused a server crash.  (Bug#27870
     (http://bugs.mysql.com/27870))

   * An error message suggested the use of `mysql_fix_privilege_tables'
     after an upgrade, but the recommended program is now
     `mysql_upgrade'.  (Bug#27818 (http://bugs.mysql.com/27818))

   * Debug builds on Windows generated false alarms about uninitialized
     variables with some Visual Studio runtime libraries.  (Bug#27811
     (http://bugs.mysql.com/27811))

   * Certain queries that used uncorrelated scalar subqueries caused
     `EXPLAIN' to crash.  (Bug#27807 (http://bugs.mysql.com/27807))

   * Performing a `UNION' on two views that had `ORDER BY' clauses
     resulted in an `Unknown column' error.  (Bug#27786
     (http://bugs.mysql.com/27786))

   * `mysql_install_db' is supposed to detect existing system tables
     and create only those that do not exist.  Instead, it was exiting
     with an error if tables already existed.  (Bug#27783
     (http://bugs.mysql.com/27783))

   * The `LEAST()' and `GREATEST()' functions compared `DATE' and
     `DATETIME' values as strings, which in some cases could lead to an
     incorrect result.  (Bug#27759 (http://bugs.mysql.com/27759))

   * A memory leak in the event scheduler was uncovered by Valgrind.
     (Bug#27733 (http://bugs.mysql.com/27733))

   * `mysqld' did not check the length of option values and could crash
     with a buffer overflow for long values.  (Bug#27715
     (http://bugs.mysql.com/27715))

   * Comparisons using row constructors could fail for rows containing
     `NULL' values.  (Bug#27704 (http://bugs.mysql.com/27704))

   * `mysqldump' could not connect using SSL.  (Bug#27669
     (http://bugs.mysql.com/27669))

   * `SELECT DISTINCT' could return incorrect results if the select
     list contained duplicated columns.  (Bug#27659
     (http://bugs.mysql.com/27659))

   * On Linux, the server could not create temporary tables if
     `lower_case_table_names' was set to 1 and the value of `tmpdir'
     was a directory name containing any uppercase letters.  (Bug#27653
     (http://bugs.mysql.com/27653))

   * For `InnoDB' tables, a multiple-row `INSERT' of the form `INSERT
     INTO t (id...) VALUES (NULL...) ON DUPLICATE KEY UPDATE
     id=VALUES(id)', where `id' is an `AUTO_INCREMENT' column, could
     cause `ERROR 1062 (23000): Duplicate entry...' errors or lost rows.
     (Bug#27650 (http://bugs.mysql.com/27650))

   * When MySQL logged slow query information to a `CSV' table, it used
     an incorrect formula to calculate the `query_time' and `lock_time'
     values.  (Bug#27638 (http://bugs.mysql.com/27638))

   * The XML output representing an empty result was an empty string
     rather than an empty `<resultset/>' element.  (Bug#27608
     (http://bugs.mysql.com/27608))

   * Comparison of a `DATE' with a `DATETIME' did not treat the `DATE'
     as having a time part of `00:00:00'.  (Bug#27590
     (http://bugs.mysql.com/27590)) See also Bug#32198
     (http://bugs.mysql.com/32198)

   * With `NO_AUTO_VALUE_ON_ZERO' SQL mode enabled, `LOAD DATA'
     operations could assign incorrect `AUTO_INCREMENT' values.
     (Bug#27586 (http://bugs.mysql.com/27586))

   * Group relay log rotation updated only the log position and not the
     name, causing the slave to stop.  (Bug#27583
     (http://bugs.mysql.com/27583))

   * Incorrect results could be returned for some queries that
     contained a select list expression with `IN' or `BETWEEN' together
     with an `ORDER BY' or `GROUP BY' on the same expression using `NOT
     IN' or `NOT BETWEEN'.  (Bug#27532 (http://bugs.mysql.com/27532))

   * The fix for Bug#17212 (http://bugs.mysql.com/17212) provided
     correct sort order for misordered output of certain queries, but
     caused significant overall query performance degradation. (Results
     were correct (good), but returned much more slowly (bad).) The fix
     also affected performance of queries for which results were
     correct.  The performance degradation has been addressed.
     (Bug#27531 (http://bugs.mysql.com/27531))

   * The `CRC32()' function returns an unsigned integer, but the
     metadata was signed, which could cause certain queries to return
     incorrect results. (For example, queries that selected a `CRC32()'
     value and used that value in the `GROUP BY' clause.)  (Bug#27530
     (http://bugs.mysql.com/27530))

   * An interaction between `SHOW TABLE STATUS' and other concurrent
     statements that modify the table could result in a divide-by-zero
     error and a server crash.  (Bug#27516
     (http://bugs.mysql.com/27516))

   * Evaluation of an `IN()' predicate containing a decimal-valued
     argument caused a server crash.  (Bug#27513
     (http://bugs.mysql.com/27513), Bug#27362
     (http://bugs.mysql.com/27362), CVE-2007-2583
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-2583))

   * A race condition between `DROP TABLE' and `SHOW TABLE STATUS'
     could cause the latter to display incorrect information.
     (Bug#27499 (http://bugs.mysql.com/27499))

   * In out-of-memory conditions, the server might crash or otherwise
     not report an error to the Windows event log.  (Bug#27490
     (http://bugs.mysql.com/27490))

   * Passing nested row expressions with different structures to an
     `IN' predicate caused a server crash.  (Bug#27484
     (http://bugs.mysql.com/27484))

   * The `decimal.h' header file was incorrectly omitted from binary
     distributions.  (Bug#27456 (http://bugs.mysql.com/27456))

   * With `innodb_file_per_table' enabled, attempting to rename an
     `InnoDB' table to a non-existent database caused the server to
     exit.  (Bug#27381 (http://bugs.mysql.com/27381))

   * Nested aggregate functions could be improperly evaluated.
     (Bug#27363 (http://bugs.mysql.com/27363))

   * A stored function invocation in the `WHERE' clause was treated as
     a constant.  (Bug#27354 (http://bugs.mysql.com/27354))

   * For the `INFORMATION_SCHEMA' `SESSION_STATUS' and `GLOBAL_STATUS'
     tables, some status values were incorrectly converted to the data
     type of the `VARIABLE_VALUE' column.  (Bug#27327
     (http://bugs.mysql.com/27327))

   * Failure to allocate memory associated with
     `transaction_prealloc_size' could cause a server crash.
     (Bug#27322 (http://bugs.mysql.com/27322))

   * A subquery could get incorrect values for references to outer
     query columns when it contained aggregate functions that were
     aggregated in outer context.  (Bug#27321
     (http://bugs.mysql.com/27321))

   * The server did not shut down cleanly.  (Bug#27310
     (http://bugs.mysql.com/27310))

   * In a view, a column that was defined using a `GEOMETRY' function
     was treated as having the `LONGBLOB' data type rather than the
     `GEOMETRY' type.  (Bug#27300 (http://bugs.mysql.com/27300))

   * `mysqldump' crashed if it got no data from `SHOW CREATE PROCEDURE'
     (for example, when trying to dump a routine defined by a different
     user and for which the current user had no privileges). Now it
     prints a comment to indicate the problem. It also returns an
     error, or continues if the `--force' option is given.  (Bug#27293
     (http://bugs.mysql.com/27293))

   * Queries containing subqueries with `COUNT(*)' aggregated in an
     outer context returned incorrect results. This happened only if
     the subquery did not contain any references to outer columns.
     (Bug#27257 (http://bugs.mysql.com/27257))

   * Use of an aggregate function from an outer context as an argument
     to `GROUP_CONCAT()' caused a server crash.  (Bug#27229
     (http://bugs.mysql.com/27229))

   * String truncation upon insertion into an integer or year column
     did not generate a warning (or an error in strict mode).
     (Bug#27176 (http://bugs.mysql.com/27176), Bug#26359
     (http://bugs.mysql.com/26359))

   * `mysqlbinlog' produced different output with the `-R' option than
     without it.  (Bug#27171 (http://bugs.mysql.com/27171))

   * Storing `NULL' values in spatial fields caused excessive memory
     allocation and crashes on some systems.  (Bug#27164
     (http://bugs.mysql.com/27164))

   * Row equalities in `WHERE' clauses could cause memory corruption.
     (Bug#27154 (http://bugs.mysql.com/27154))

   * `ON DUPLICATE KEY UPDATE' failed for a table partitioned by `KEY'
     on a primary key `VARCHAR' column.  (Bug#27123
     (http://bugs.mysql.com/27123))

   * `GROUP BY' on a `ucs2' column caused a server crash when there was
     at least one empty string in the column.  (Bug#27079
     (http://bugs.mysql.com/27079))

   * Duplicate members in `SET' or `ENUM' definitions were not
     detected. Now they result in a warning; if strict SQL mode is
     enabled, an error occurs instead.  (Bug#27069
     (http://bugs.mysql.com/27069))

   * For `FEDERATED' tables, `SHOW CREATE TABLE' could fail when the
     table name was longer than the connection name.  (Bug#27036
     (http://bugs.mysql.com/27036))

   * `mysql_install_db' could terminate with an error after failing to
     determine that a system table already existed.  (Bug#27022
     (http://bugs.mysql.com/27022))

   * In a `MEMORY' table, using a `BTREE' index to scan for updatable
     rows could lead to an infinite loop.  (Bug#26996
     (http://bugs.mysql.com/26996))

   * `make_win_bin_dist' neglected to copy some required `MyISAM' table
     files.  (Bug#26922 (http://bugs.mysql.com/26922))

   * Improved out-of-memory detection when sending logs from a master
     server to slaves, and log a message when allocation fails.
     (Bug#26837 (http://bugs.mysql.com/26837))

   * For `InnoDB' tables having a clustered index that began with a
     `CHAR' or `VARCHAR' column, deleting a record and then inserting
     another before the deleted record was purged could result in table
     corruption.  (Bug#26835 (http://bugs.mysql.com/26835))

   * `mysqldump' would not dump a view for which the `DEFINER' no
     longer exists.  (Bug#26817 (http://bugs.mysql.com/26817))

   * Duplicates were not properly identified among (potentially) long
     strings used as arguments for `GROUP_CONCAT(DISTINCT)'.
     (Bug#26815 (http://bugs.mysql.com/26815))

   * `ALTER VIEW' requires the `CREATE VIEW' and `DROP' privileges for
     the view. However, if the view was created by another user, the
     server erroneously required the `SUPER' privilege.  (Bug#26813
     (http://bugs.mysql.com/26813))

   * If the name of a table given to `myisamchk -rq' was a packed table
     and the name included the `.MYI' extension, `myisamchk'
     incorrectly created a file with a `.MYI.MYI' extension.
     (Bug#26782 (http://bugs.mysql.com/26782))

   * Creating a temporary table with `InnoDB' when using the
     one-file-per-table setting, and when the host filesystem for
     temporary tables was `tmpfs', would cause an assertion within
     `mysqld'. This was due to the use of `O_DIRECT' when opening the
     temporary table file.  (Bug#26662 (http://bugs.mysql.com/26662))

   * `mysql_upgrade' did not detect failure of external commands that
     it runs.  (Bug#26639 (http://bugs.mysql.com/26639))

   * The range optimizer could cause the server to run out of memory.
     (Bug#26625 (http://bugs.mysql.com/26625))

   * The range optimizer could consume a combinatorial amount of memory
     for certain classes of `WHERE' clauses.  (Bug#26624
     (http://bugs.mysql.com/26624))

   * Aborting a statement on the master that applied to a
     non-transactional statement broke replication. The statement was
     written to the binary log but not completely executed on the
     master. Slaves receiving the statement executed it completely,
     resulting in loss of data synchrony. Now an error code is written
     to the error log so that the slaves stop without executing the
     aborted statement. (That is, replication stops, but synchrony to
     the point of the stop is preserved and you can investigate the
     problem.)  (Bug#26551 (http://bugs.mysql.com/26551))

   * `mysqldump' could crash or exhibit incorrect behavior when some
     options were given very long values, such as
     `--fields-terminated-by="SOME VERY LONG STRING"'. The code has
     been cleaned up to remove a number of fixed-sized buffers and to
     be more careful about error conditions in memory allocation.
     (Bug#26346 (http://bugs.mysql.com/26346))

   * A possible buffer overflow in `SHOW PROCEDURE CODE' was removed.
     (Bug#26303 (http://bugs.mysql.com/26303))

   * The `FEDERATED' engine did not allow the local and remote tables
     to have different names.  (Bug#26257 (http://bugs.mysql.com/26257))

   * The temporary file-creation code was cleaned up on Windows to
     improve server stability.  (Bug#26233
     (http://bugs.mysql.com/26233))

   * For `MyISAM' tables, `COUNT(*)' could return an incorrect value if
     the `WHERE' clause compared an indexed `TEXT' column to the empty
     string (`'''). This happened if the column contained empty strings
     and also strings starting with control characters such as tab or
     newline.  (Bug#26231 (http://bugs.mysql.com/26231))

   * For `INSERT INTO ... SELECT' where index searches used column
     prefixes, insert errors could occur when key value type conversion
     was done.  (Bug#26207 (http://bugs.mysql.com/26207))

   * `mysqlbinlog --base64-output' produced invalid SQL.  (Bug#26194
     (http://bugs.mysql.com/26194))

   * For `DELETE FROM `tbl_name' ORDER BY COL_NAME' (with no `WHERE' or
     `LIMIT' clause), the server did not check whether COL_NAME was a
     valid column in the table.  (Bug#26186
     (http://bugs.mysql.com/26186))

   * Executing an `INSERT ... SELECT ... FROM
     INFORMATION_SCHEMA.GLOBAL_STATUS' statement from within an event
     caused a server crash.  (Bug#26174 (http://bugs.mysql.com/26174))

   * `mysqldump' could not dump log tables.  (Bug#26121
     (http://bugs.mysql.com/26121))

   * On Windows, trying to use backslash (`\') characters in paths for
     `DATA DIRECTORY' and `INDEX DIRECTORY' when creating partitioned
     tables caused MySQL to crash.

     (You must use `/' characters when specifying paths for these
     options, regardless of platform. See *Note
     partitioning-overview::, for an example using absolute paths for
     `DATA DIRECTORY' and `INDEX DIRECTORY' when creating a partitioned
     table on Windows.)  (Bug#26074 (http://bugs.mysql.com/26074),
     Bug#25141 (http://bugs.mysql.com/25141))

   * `mysqldump' crashed for `MERGE' tables if the `--complete-insert'
     (`-c') option was given.  (Bug#25993 (http://bugs.mysql.com/25993))

   * Index hints (`USE INDEX', `IGNORE INDEX', `FORCE INDEX') cannot be
     used with `FULLTEXT' indexes, but were not being ignored.
     (Bug#25951 (http://bugs.mysql.com/25951))

   * Setting a column to `NOT NULL' with an `ON DELETE SET NULL' clause
     foreign key crashes the server.  (Bug#25927
     (http://bugs.mysql.com/25927))

   * Corrupted `MyISAM' tables that have different definitions in the
     `.frm' and `.MYI' tables might cause a server crash.  (Bug#25908
     (http://bugs.mysql.com/25908))

   * If `CREATE TABLE t1 LIKE t2' failed due to a full disk, an empty
     `t2.frm' file could be created but not removed. This file then
     caused subsequent attempts to create a table named `t2' to fail.
     This is easily corrected at the filesystem level by removing the
     `t2.frm' file manually, but now the server removes the file if the
     create operation does not complete successfully.  (Bug#25761
     (http://bugs.mysql.com/25761))

   * In certain situations, `MATCH ... AGAINST' returned false hits for
     `NULL' values produced by `LEFT JOIN' when no full-text index was
     available.  (Bug#25729 (http://bugs.mysql.com/25729))

   * Concurrent `CREATE SERVER' and `ALTER SERVER' statements could
     cause a deadlock.  (Bug#25721 (http://bugs.mysql.com/25721))

   * `CREATE SERVER', `DROP SERVER', and `ALTER SERVER' did not require
     any privileges. Now these statements require the `SUPER' privilege.
     (Bug#25671 (http://bugs.mysql.com/25671))

   * On Windows, connection handlers did not properly decrement the
     server's thread count when exiting.  (Bug#25621
     (http://bugs.mysql.com/25621))

   * When `RAND()' was called multiple times inside a stored procedure,
     the server did not write the correct random seed values to the
     binary log, resulting in incorrect replication.  (Bug#25543
     (http://bugs.mysql.com/25543))

   * `OPTIMIZE TABLE' might fail on Windows when it attempts to rename
     a temporary file to the original name if the original file had
     been opened, resulting in loss of the `.MYD' file.  (Bug#25521
     (http://bugs.mysql.com/25521))

   * For `SHOW ENGINE INNODB STATUS', the `LATEST DEADLOCK INFORMATION'
     was not always cleared properly.  (Bug#25494
     (http://bugs.mysql.com/25494))

   * *Note `mysql_stmt_fetch()': mysql-stmt-fetch. did an invalid
     memory deallocation when used with the embedded server.
     (Bug#25492 (http://bugs.mysql.com/25492))

   * `GRANT' statements were not replicated if the server was started
     with the `--replicate-ignore-table' or
     `--replicate-wild-ignore-table' option.  (Bug#25482
     (http://bugs.mysql.com/25482))

   * `mysql_upgrade' did not pass a password to `mysqlcheck' if one was
     given.  (Bug#25452 (http://bugs.mysql.com/25452))

   * On Windows, `mysql_upgrade' was sensitive to lettercase of the
     names of some required components.  (Bug#25405
     (http://bugs.mysql.com/25405))

   * During a call to *Note `mysql_change_user()': mysql-change-user,
     when authentication fails or the database to change to is unknown,
     a subsequent call to any function that does network communication
     leads to packets out of order. This problem was introduced in
     MySQL 5.1.14.  (Bug#25371 (http://bugs.mysql.com/25371))

   * Difficult repair or optimization operations could cause an
     assertion failure, resulting in a server crash.  (Bug#25289
     (http://bugs.mysql.com/25289))

   * For storage engines that allow the current auto-increment value to
     be set, using `ALTER TABLE ... ENGINE' to convert a table from one
     such storage engine to another caused loss of the current value.
     (For storage engines that do not support setting the value, it
     cannot be retained anyway when changing the storage engine.)
     (Bug#25262 (http://bugs.mysql.com/25262))

   * Restoration of the default database after stored routine or
     trigger execution on a slave could cause replication to stop if
     the database no longer existed.  (Bug#25082
     (http://bugs.mysql.com/25082))

   * Duplicate entries were not assessed correctly in a `MEMORY' table
     with a `BTREE' primary key on a `utf8' `ENUM' column.  (Bug#24985
     (http://bugs.mysql.com/24985))

   * Several math functions produced incorrect results for large
     unsigned values. `ROUND()' produced incorrect results or a crash
     for a large number-of-decimals argument.  (Bug#24912
     (http://bugs.mysql.com/24912))

   * The result set of a query that used `WITH ROLLUP' and `DISTINCT'
     could lack some rollup rows (rows with `NULL' values for grouping
     attributes) if the `GROUP BY' list contained constant expressions.
     (Bug#24856 (http://bugs.mysql.com/24856))

   * Selecting the result of `AVG()' within a `UNION' could produce
     incorrect values.  (Bug#24791 (http://bugs.mysql.com/24791))

   * For queries that used `ORDER BY' with `InnoDB' tables, if the
     optimizer chose an index for accessing the table but found a
     covering index that enabled the `ORDER BY' to be skipped, no
     results were returned.  (Bug#24778 (http://bugs.mysql.com/24778))

   * The `NO_DIR_IN_CREATE' server SQL mode was not enforced for
     partitioned tables.  (Bug#24633 (http://bugs.mysql.com/24633))

   * `MBRDisjoint()', `MBRequal()', `MBRIntersects()', `MBROverlaps()',
     `MBRTouches()', and `MBRWithin()' were inadvertently omitted from
     recent versions of MySQL (5.1.14 to 5.1.17).  (Bug#24588
     (http://bugs.mysql.com/24588))

   * Access via `my_pread()' or `my_pwrite()' to table files larger
     than 2GB could fail on some systems.  (Bug#24566
     (http://bugs.mysql.com/24566))

   * `MBROverlaps()' returned incorrect values in some cases.
     (Bug#24563 (http://bugs.mysql.com/24563))

   * A problem in handling of aggregate functions in subqueries caused
     predicates containing aggregate functions to be ignored during
     query execution.  (Bug#24484 (http://bugs.mysql.com/24484))

   * The `MERGE' storage engine could return incorrect results when
     several index values that compare equality were present in an
     index (for example, `'gross'' and `'gross '', which are considered
     equal but have different lengths).  (Bug#24342
     (http://bugs.mysql.com/24342))

   * Some upgrade problems are detected and better error messages
     suggesting that `mysql_upgrade' be run are produced.  (Bug#24248
     (http://bugs.mysql.com/24248))

   * The test for the `MYSQL_OPT_SSL_VERIFY_SERVER_CERT' option for
     *Note `mysql_options()': mysql-options. was performed incorrectly.
     Also changed as a result of this bugfix: The `arg' option for the
     *Note `mysql_options()': mysql-options. C API function was changed
     from `char *' to `void *'.  (Bug#24121
     (http://bugs.mysql.com/24121))

   * Some views could not be created even when the user had the
     requisite privileges.  (Bug#24040 (http://bugs.mysql.com/24040))

   * The values displayed for the `Innodb_row_lock_time',
     `Innodb_row_lock_time_avg', and `Innodb_row_lock_time_max' status
     variables were incorrect.  (Bug#23666
     (http://bugs.mysql.com/23666))

   * Using `CAST()' to convert `DATETIME' values to numeric values did
     not work.  (Bug#23656 (http://bugs.mysql.com/23656))

   * A damaged or missing `mysql.event' table caused `SHOW VARIABLES'
     to fail.  (Bug#23631 (http://bugs.mysql.com/23631))

   * `SHOW CREATE VIEW' qualified references to stored functions in the
     view definition with the function's database name, even when the
     database was the default database.  This affected `mysqldump'
     (which uses `SHOW CREATE VIEW' to dump views) because the
     resulting dump file could not be used to reload the database into
     a different database. `SHOW CREATE VIEW' now suppresses the
     database name for references to functions in the default database.
     (Bug#23491 (http://bugs.mysql.com/23491))

   * An `INTO OUTFILE' clause is allowed only for the final `SELECT' of
     a `UNION', but this restriction was not being enforced correctly.
     (Bug#23345 (http://bugs.mysql.com/23345))

   * The `AUTO_INCREMENT' value would not be correctly reported for
     `InnoDB' tables when using `SHOW CREATE TABLE' statement or
     `mysqldump' command.  (Bug#23313 (http://bugs.mysql.com/23313))

   * With the `NO_AUTO_VALUE_ON_ZERO' SQL mode enabled,
     `LAST_INSERT_ID()' could return 0 after `INSERT ... ON DUPLICATE
     KEY UPDATE'. Additionally, the next rows inserted (by the same
     `INSERT', or the following `INSERT' with or without `ON DUPLICATE
     KEY UPDATE'), would insert 0 for the auto-generated value if the
     value for the `AUTO_INCREMENT' column was `NULL' or missing.
     (Bug#23233 (http://bugs.mysql.com/23233))

   * If a rotate event occured in the middle of a non-transaction
     group, the group position would be updated by the rotate event
     indicating an illegal group start position that was effectively
     inside a group. This can happen if, for example, a rotate occurs
     between an `Intvar' event and the associated `Query' event, or
     between the table map events and the rows events when using
     row-based replication.  (Bug#23171 (http://bugs.mysql.com/23171))

   * Implicit conversion of `9912101' to `DATE' did not match
     `CAST(9912101 AS DATE)'.  (Bug#23093 (http://bugs.mysql.com/23093))

   * `SELECT COUNT(*)' from a table containing a `DATETIME NOT NULL'
     column could produce spurious warnings with the `NO_ZERO_DATE' SQL
     mode enabled.  (Bug#22824 (http://bugs.mysql.com/22824))

   * Using `SET GLOBAL' to change the `lc_time_names' system variable
     had no effect on new connections.  (Bug#22648
     (http://bugs.mysql.com/22648))

   * `SOUNDEX()' returned an invalid string for international
     characters in multi-byte character sets.  (Bug#22638
     (http://bugs.mysql.com/22638))

   * Row-based replication of `MyISAM' to non-`MyISAM' tables did not
     work correctly for `BIT' columns. This has been corrected, but the
     fix introduces an incompatibility into the binary log format.
     (The incompatibility is corrected by the fix for Bug#27779
     (http://bugs.mysql.com/27779).)  (Bug#22583
     (http://bugs.mysql.com/22583))

   * A multiple-table `UPDATE' could return an incorrect rows-matched
     value if, during insertion of rows into a temporary table, the
     table had to be converted from a `MEMORY' table to a `MyISAM'
     table.  (Bug#22364 (http://bugs.mysql.com/22364))

   * `COUNT(DECIMAL_EXPR)' sometimes generated a spurious truncation
     warning.  (Bug#21976 (http://bugs.mysql.com/21976))

   * yaSSL crashed on pre-Pentium Intel CPUs.  (Bug#21765
     (http://bugs.mysql.com/21765))

   * A slave that used `--master-ssl-cipher' could not connect to the
     master.  (Bug#21611 (http://bugs.mysql.com/21611))

   * Database and table names have a maximum length of 64 characters
     (even if they contain multi-byte characters), but were truncated
     to 64 bytes.

     *Note*:

     This improves on a previous fix made for this bug in MySQL 5.1.12.

     (Bug#21432 (http://bugs.mysql.com/21432))

   * `InnoDB': The first read statement, if served from the query
     cache, was not consistent with the `READ COMMITTED' isolation
     level.  (Bug#21409 (http://bugs.mysql.com/21409))

   * On Windows, if the server was installed as a service, it did not
     auto-detect the location of the data directory.  (Bug#20376
     (http://bugs.mysql.com/20376))

   * Changing a `utf8' column in an `InnoDB' table to a shorter length
     did not shorten the data values.  (Bug#20095
     (http://bugs.mysql.com/20095))

   * In some cases, the optimizer preferred a range or full index scan
     access method over lookup access methods when the latter were much
     cheaper.  (Bug#19372 (http://bugs.mysql.com/19372))

   * Conversion of `DATETIME' values in numeric contexts sometimes did
     not produce a double (`YYYYMMDDHHMMSS.uuuuuu') value.  (Bug#16546
     (http://bugs.mysql.com/16546))

   * `INSERT...ON DUPLICATE KEY UPDATE' could cause `Error 1032: Can't
     find record in ...' for inserts into an `InnoDB' table unique index
     using key column prefixes with an underlying `utf8' string column.
     (Bug#13191 (http://bugs.mysql.com/13191))

   * Having the `EXECUTE' privilege for a routine in a database should
     make it possible to `USE' that database, but the server returned
     an error instead. This has been corrected. As a result of the
     change, `SHOW TABLES' for a database in which you have only the
     `EXECUTE' privilege returns an empty set rather than an error.
     (Bug#9504 (http://bugs.mysql.com/9504))


File: manual.info,  Node: news-5-1-17,  Next: news-5-1-16,  Prev: news-5-1-18,  Up: news-5-1-x

C.1.13 Changes in MySQL 5.1.17 (04 April 2007)
----------------------------------------------

This is a new Beta development release, fixing recently discovered bugs.

*Note*:

This Beta release, as any other pre-production release, should not be
installed on _production_ level systems or systems with critical data.
It is good practice to back up your data before installing any new
version of software.  Although MySQL has worked very hard to ensure a
high level of quality, protect your data by making a backup as you
would for any software beta release. Please refer to our bug database at
`http://bugs.mysql.com/' for more details about the individual bugs
fixed in this version.

This section documents all changes and bug fixes that have been applied
since the last official MySQL release. If you would like to receive
more fine-grained and personalized _update alerts_ about fixes that are
relevant to the version and features you use, please consider
subscribing to _MySQL Enterprise_ (a commercial MySQL offering). For
more details please see `http://www.mysql.com/products/enterprise'.

Functionality added or changed:

   * *Incompatible Change*: Scheduled events now use the MySQL server
     time zone to determine their schedules, rather than UTC as in
     previous releases.  Because of this change, scheduled event
     metadata now includes time zone information, which can be seen in
     the `TIME_ZONE' column of the `INFORMATION_SCHEMA.EVENTS' table
     and the `Time zone' column in the output of the `SHOW EVENTS'
     statement. These columns have been added in this release, along
     with a `time_zone' column in the `mysql.event' table. Due to these
     changes, events created in previous versions of MySQL cannot be
     created, viewed, or used until `mysql.event' has been upgraded.
     (Bug#16420 (http://bugs.mysql.com/16420))

   * *Important Change*: The `CREATE EVENT' and `ALTER EVENT'
     statements now support a `DEFINER' clause, similar to that used in
     the `CREATE TRIGGER' statement.

     See *Note create-event::, for detailed information.  (Bug#16425
     (http://bugs.mysql.com/16425))

   * *Important Change*: The following options for controlling
     replication master configuration on a slave are now deprecated.

        * `--master-host'

        * `--master-user'

        * `--master-password '

        * `--master-port'

        * `--master-connect-retry'

        * `--master-ssl'

        * `--master-ssl-ca'

        * `--master-ssl-capath'

        * `--master-ssl-cert'

        * `--master-ssl-cipher'

        * `--master-ssl-key'

     To change the master configuration on a slave you should use the
     `CHANGE MASTER' statement.

     See also Bug#21490 (http://bugs.mysql.com/21490)

   * *MySQL Cluster*: Added the `--skip-table-check' option (short form
     `-s') for `ndb_restore', which causes the restoration process to
     ignore any changes that may have occurred in table schemas after
     the backup was made.  Previously, this was the default behavior.

     See *Note mysql-cluster-restore::, for more information.
     (Bug#24363 (http://bugs.mysql.com/24363))

   * Added a `--no-beep' option to `mysqladmin'. It suppresses the
     warning beep that is emitted by default for errors such as a
     failure to connect to the server.  (Bug#26964
     (http://bugs.mysql.com/26964))

   * Added the `--service-startup-timeout' option for `mysql.server' to
     specify how long to wait for the server to start. If the server
     does not start within the timeout period, `mysql.server' exits
     with an error.  (Bug#26952 (http://bugs.mysql.com/26952))

   * Prefix lengths for columns in `SPATIAL' indexes can no longer be
     specified. For tables created in older versions of MySQL that have
     `SPATIAL' indexes containing prefixed columns, dumping and
     reloading the table causes the indexes to be created with no
     prefixes. (The full column width of each column is indexed.)
     (Bug#26794 (http://bugs.mysql.com/26794))

   * Added the `innodb_stats_on_metadata' system variable to enable
     control over whether `InnoDB' performs statistics gathering when
     metadata statements are executed. See *Note innodb-parameters::.
     (Bug#26598 (http://bugs.mysql.com/26598))

   * Statements that affect `mysql' database tables now are written to
     the binary log using the following rules:

        * Data manipulation statements such as `INSERT' that change
          data in `mysql' database tables directly are logged according
          to the settings of the `binlog_format' system variable.

        * Statements such as `GRANT' that change the `mysql' database
          indirectly are logged as statements regardless of the value of
          `binlog_format'.

     For more details, see *Note binary-log-mysql-database::.
     (Bug#25091 (http://bugs.mysql.com/25091))

   * The server now includes a timestamp in error messages that are
     logged as a result of unhandled signals (such as `mysqld got
     signal 11' messages).  (Bug#24878 (http://bugs.mysql.com/24878))

   * The syntax for index hints has been extended to enable more
     fine-grained control over the optimizer's selection of an
     execution plan for various phases of query processing. See *Note
     index-hints::.  (Bug#21174 (http://bugs.mysql.com/21174))

   * Added the `--secure-file-priv' option for `mysqld', which limits
     the effect of the `LOAD_FILE()' function and the `LOAD DATA' and
     `SELECT ...  INTO OUTFILE' statements to work only with files in a
     given directory.  (Bug#18628 (http://bugs.mysql.com/18628))

   * Added the `thread_handling' system variable to control whether the
     server use a single thread or one thread per connection. The
     `--one-thread' option now is deprecated; use
     `--thread_handling=one-thread' instead.

   * Prepared statements now use the query cache under the conditions
     described in *Note query-cache-how::.  (Bug#735
     (http://bugs.mysql.com/735))

   * Statements such as `GRANT' that change the `mysql' database
     indirectly are logged as statements regardless of the value of
     `binlog_format'.

   * Added the `hostname' system variable, which the server sets at
     startup to the server hostname.

   * Online (non-copying) `ADD INDEX' and `DROP INDEX' operations are
     now performed on dynamic (variable-width) columns. Renaming of
     `NDB' and `MyISAM' tables and of columns in such tables is now
     performed without copying or locking the tables. As a result,
     these operations are now performed much more quickly than
     previously.

     See *Note alter-table::, *Note create-index::, and *Note
     drop-index::, for more information.

   * Data manipulation statements such as `INSERT' that change data in
     `mysql' database tables directly are logged according to the
     settings of the `binlog_format' system variable.

   * Added the `old_mode' system variable to cause the server to revert
     to certain behaviors present in older versions. Currently, this
     variable affects handling of index hints. See *Note index-hints::.

Bugs fixed:

   * *Incompatible Change*: `INSERT DELAYED' statements are not
     supported for `MERGE' tables, but the `MERGE' storage engine was
     not rejecting such statements, resulting in table corruption.
     Applications previously using `INSERT DELAYED' into `MERGE' table
     will break when upgrading to versions with this fix. To avoid the
     problem, remove `DELAYED' from such statements.  (Bug#26464
     (http://bugs.mysql.com/26464))

   * *Important Note*: The parser accepted invalid code in SQL
     condition handlers, leading to server crashes or unexpected
     execution behavior in stored programs. Specifically, the parser
     allowed a condition handler to refer to labels for blocks that
     enclose the handler declaration. This was incorrect because block
     label scope does not include the code for handlers declared within
     the labeled block.

     The parser now rejects this invalid construct, but if you upgrade
     in place (without dumping and reloading your databases), existing
     handlers that contain the construct are still invalid -- _even if
     they appear to function as you expect_ -- and should be rewritten.

     To find affected handlers, use `mysqldump' to dump all stored
     functions and procedures, triggers, and events.  Then attempt to
     reload them into an upgraded server. Handlers that contain illegal
     label references will be rejected.

     For more information about condition handlers and writing them to
     avoid invalid jumps, see *Note declare-handlers::.  (Bug#26503
     (http://bugs.mysql.com/26503))

   * *MySQL Cluster*: It was not possible to set
     `LockPagesInMainMemory' equal to `0'.  (Bug#27291
     (http://bugs.mysql.com/27291))

   * *MySQL Cluster*: A race condition could sometimes occur if the
     node acting as master failed while node IDs were still being
     allocated during startup.  (Bug#27286
     (http://bugs.mysql.com/27286))

   * *MySQL Cluster*: When a data node was taking over as the master
     node, a race condition could sometimes occur as the node was
     assuming responsibility for handling of global checkpoints.
     (Bug#27283 (http://bugs.mysql.com/27283))

   * *MySQL Cluster*: After putting the cluster in single user mode
     from one MySQL server, trying to drop an `NDB' table from a second
     MySQL server also connected to the cluster would cause the second
     MySQL server to hang.  (Bug#27254 (http://bugs.mysql.com/27254))

   * *MySQL Cluster*: `mysqld' could crash shortly after a data node
     failure following certain DML operations.  (Bug#27169
     (http://bugs.mysql.com/27169))

   * *MySQL Cluster*: (Disk Data): Under some circumstances, a data
     node could fail during restart while flushing Disk Data UNDO logs.
     (Bug#27102 (http://bugs.mysql.com/27102))

   * *MySQL Cluster*: The same failed request from an API node could be
     handled by the cluster multiple times, resulting in reduced
     performance.  (Bug#27087 (http://bugs.mysql.com/27087))

   * *MySQL Cluster*: The failure of a data node while restarting could
     cause other data nodes to hang or crash.  (Bug#27003
     (http://bugs.mysql.com/27003))

   * *MySQL Cluster*: Creating a table on one SQL node while in single
     user mode caused other SQL nodes to crash.  (Bug#26997
     (http://bugs.mysql.com/26997))

   * *MySQL Cluster*: `mysqld' processes would sometimes crash under
     high load.  (Bug#26825 (http://bugs.mysql.com/26825))

   * *MySQL Cluster*: Using only the `--print_data' option (and no
     other options) with `ndb_restore' caused `ndb_restore' to fail.
     (Bug#26741 (http://bugs.mysql.com/26741)) This regression was
     introduced by Bug#14612 (http://bugs.mysql.com/14612)

   * *MySQL Cluster*: The output from `ndb_restore `--print_data'' was
     incorrect for a backup made of a database containing tables with
     `TINYINT' or `SMALLINT' columns.  (Bug#26740
     (http://bugs.mysql.com/26740))

   * *MySQL Cluster*: An infinite loop in an internal logging function
     could cause trace logs to fill up with `Unknown Signal type' error
     messages and thus grow to unreasonable sizes.  (Bug#26720
     (http://bugs.mysql.com/26720))

   * *MySQL Cluster*: An invalid pointer was returned following a
     `FSCLOSECONF' signal when accessing the REDO logs during a node
     restart or system restart.  (Bug#26515
     (http://bugs.mysql.com/26515))

   * *MySQL Cluster*: The management client command ` NODE_ID STATUS'
     displayed the message `Node NODE_ID: not connected' when NODE_ID
     was not the node ID of a data node.

     *Note*:

     The `ALL STATUS' command in the cluster management client still
     displays status information for data nodes only. This is by
     design. See *Note mysql-cluster-mgm-client-commands::, for more
     information.

     (Bug#21715 (http://bugs.mysql.com/21715))

   * *MySQL Cluster*: When performing an upgrade or downgrade, no
     specific error information was made available when trying to
     upgrade data nodes or SQL nodes before upgrading management nodes.
     (Bug#21296 (http://bugs.mysql.com/21296))

   * *MySQL Cluster*: Some values of `MaxNoOfTables' caused the error
     `Job buffer congestion' to occur.  (Bug#19378
     (http://bugs.mysql.com/19378))

   * *Disk Data*: A memory overflow could occur with tables having a
     large amount of data stored on disk, or with queries using a very
     high degree of parallelism on Disk Data tables.  (Bug#26514
     (http://bugs.mysql.com/26514))

   * *Disk Data*: Use of a tablespace whose `INITIAL_SIZE' was greater
     than 1 GB could cause the cluster to crash.  (Bug#26487
     (http://bugs.mysql.com/26487))

   * *Disk Data*: Creating multiple Disk Data tables using different
     tablespaces could sometimes cause the cluster to fail.  (Bug#25992
     (http://bugs.mysql.com/25992))

   * *Disk Data*: `ALTER TABLE ... ADD COLUMN ...' on a Disk Data table
     moved data for existing non-indexed columns from the tablespace
     into memory.  (Bug#25880 (http://bugs.mysql.com/25880))

   * *Disk Data*: `DROP INDEX' on a Disk Data table did not always move
     data from memory into the tablespace.  (Bug#25877
     (http://bugs.mysql.com/25877))

   * *Disk Data*: When creating a log file group, setting
     `INITIAL_SIZE' to less than `UNDO_BUFFER_SIZE' caused data nodes
     to crash.  (Bug#25743 (http://bugs.mysql.com/25743))

   * *Cluster Replication*: The simultaneous failure of a data node and
     an SQL node could cause replication to fail.  (Bug#27005
     (http://bugs.mysql.com/27005))

   * *Cluster API*: A delete operation using a scan followed by an
     insert using a scan could cause a data node to fail.  (Bug#27203
     (http://bugs.mysql.com/27203))

   * *Cluster API*: (Cluster APIs): `NAND' and `NOR' operations with
     `NdbScanFilter' did not perform correctly.  (Bug#24568
     (http://bugs.mysql.com/24568))

   * *Cluster API*: You can now use the `ndb_mgm_check_connection()'
     function to determine whether a management server is running. See
     `ndb_mgm_check_connection()'
     (http://dev.mysql.com/doc/ndbapi/en/ndb-mgm-check-connection.html).

   * `SELECT ... INTO OUTFILE' with a long `FIELDS ENCLOSED BY' value
     could crash the server.  (Bug#27231 (http://bugs.mysql.com/27231))

   * An `INSERT ... ON DUPLICATE KEY UPDATE' statement might modify
     values in a table but not flush affected data from the query
     cache, causing subsequent selects to return stale results. This
     made the combination of query cache plus `ON DUPLICATE KEY UPDATE'
     very unreliable.  (Bug#27210 (http://bugs.mysql.com/27210)) See
     also Bug#27006 (http://bugs.mysql.com/27006), Bug#27033
     (http://bugs.mysql.com/27033)

     This regression was introduced by Bug#19978
     (http://bugs.mysql.com/19978)

   * For `INSERT ... ON DUPLICATE KEY UPDATE' statements on tables
     containing `AUTO_INCREMENT' columns, `LAST_INSERT_ID()' was reset
     to 0 if no rows were successfully inserted or changed. `Not
     changed' includes the case where a row was updated to its current
     values, but in that case, `LAST_INSERT_ID()' should not be reset
     to 0. Now `LAST_INSERT_ID()' is reset to 0 only if no rows were
     successfully inserted or touched, whether or not touched rows were
     changed.  (Bug#27033 (http://bugs.mysql.com/27033)) See also
     Bug#27210 (http://bugs.mysql.com/27210), Bug#27006
     (http://bugs.mysql.com/27006)

     This regression was introduced by Bug#19978
     (http://bugs.mysql.com/19978)

   * Invalid optimization of pushdown conditions for queries where an
     outer join was guaranteed to read only one row from the outer
     table led to results with too few rows.  (Bug#26963
     (http://bugs.mysql.com/26963))

   * For `MERGE' tables defined on underlying tables that contained a
     short `VARCHAR' column (shorter than four characters), using `ALTER
     TABLE' on at least one but not all of the underlying tables caused
     the table definitions to be considered different from that of the
     `MERGE' table, even if the `ALTER TABLE' did not change the
     definition.  (Bug#26881 (http://bugs.mysql.com/26881))

   * Use of a subquery containing `GROUP BY' and `WITH ROLLUP' caused a
     server crash.  (Bug#26830 (http://bugs.mysql.com/26830))

   * Setting `event_scheduler=1' or `event_scheduler=ON' caused the
     server to crash if the server had been started with
     `--skip-grant-tables'. Starting the server with
     `--skip-grant-tables' now causes `event_scheduler' to be set to
     `DISABLED' automatically, overriding any other value that may have
     been set.  (Bug#26807 (http://bugs.mysql.com/26807))

   * Added support for `--debugger=dbx' for `mysql-test-run.pl' and
     added support for `--debugger=devenv', `--debugger=DevEnv', and
     `--debugger=/PATH/TO/devenv'.  (Bug#26792
     (http://bugs.mysql.com/26792))

   * A result set column formed by concatention of string literals was
     incomplete when the column was produced by a subquery in the
     `FROM' clause.  (Bug#26738 (http://bugs.mysql.com/26738))

   * SSL connections failed on Windows.  (Bug#26678
     (http://bugs.mysql.com/26678))

   * When using the result of `SEC_TO_TIME()' for time value greater
     than 24 hours in an `ORDER BY' clause, either directly or through
     a column alias, the rows were sorted incorrectly as strings.
     (Bug#26672 (http://bugs.mysql.com/26672))

   * Use of a subquery containing a `UNION' with an invalid `ORDER BY'
     clause caused a server crash.  (Bug#26661
     (http://bugs.mysql.com/26661))

   * In some error messages, inconsistent format specifiers were used
     for the translations in different languages.  `comp_err' (the
     error message compiler) now checks for mismatches.  (Bug#26571
     (http://bugs.mysql.com/26571))

   * Views that used a scalar correlated subquery returned incorrect
     results.  (Bug#26560 (http://bugs.mysql.com/26560))

   * `UNHEX() IS NULL' comparisons failed when `UNHEX()' returned
     `NULL'.  (Bug#26537 (http://bugs.mysql.com/26537))

   * On 64-bit Windows, large timestamp values could be handled
     incorrectly.  (Bug#26536 (http://bugs.mysql.com/26536))

   * `SHOW CREATE EVENT' failed to display the `STARTS' and `ENDS'
     clauses for an event defined with `STARTS NOW()', `ENDS NOW()', or
     both.  (Bug#26429 (http://bugs.mysql.com/26429))

   * If the server was started with `--skip-grant-tables', Selecting
     from `INFORMATION_SCHEMA' tables causes a server crash.
     (Bug#26285 (http://bugs.mysql.com/26285))

   * For some values of the position argument, the `INSERT()' function
     could insert a NUL byte into the result.  (Bug#26281
     (http://bugs.mysql.com/26281))

   * For an `INSERT' statement that should fail due to a column with no
     default value not being assigned a value, the statement succeeded
     with no error if the column was assigned a value in an `ON
     DUPLICATE KEY UPDATE' clause, even if that clause was not used.
     (Bug#26261 (http://bugs.mysql.com/26261))

   * `INSERT DELAYED' statements inserted incorrect values into `BIT'
     columns.  (Bug#26238 (http://bugs.mysql.com/26238))

   * A query of type `index_merge', and with a `WHERE' clause having
     the form `WHERE INDEXED_COLUMN_1=VALUE_1 OR
     INDEXED_COLUMN_2=VALUE_2 ' on a partitioned table caused the
     server to crash.  (Bug#26117 (http://bugs.mysql.com/26117))

   * A multiple-row delayed insert with an auto-increment column could
     cause duplicate entries to be created on the slave in a
     replication environment.  (Bug#26116
     (http://bugs.mysql.com/26116), Bug#25507
     (http://bugs.mysql.com/25507))

   * `BENCHMARK()' did not work correctly for expressions that produced
     a `DECIMAL' result.  (Bug#26093 (http://bugs.mysql.com/26093))

   * For `MEMORY' tables, extending the length of a `VARCHAR' column
     with `ALTER TABLE' might result in an unusable table.  (Bug#26080
     (http://bugs.mysql.com/26080))

   * The server could hang during binary log rotation.  (Bug#26079
     (http://bugs.mysql.com/26079))

   * `LOAD DATA INFILE' sent an okay to the client before writing the
     binary log and committing the changes to the table had finished,
     thus violating ACID requirements.  (Bug#26050
     (http://bugs.mysql.com/26050))

   * `X() IS NULL' and `Y() IS NULL' comparisons failed when `X()' and
     `Y()' returned `NULL'.  (Bug#26038 (http://bugs.mysql.com/26038))

   * Indexes on `TEXT' columns were ignored when `ref' accesses were
     evaluated.  (Bug#25971 (http://bugs.mysql.com/25971))

   * If a thread previously serviced a connection that was killed,
     excessive memory and CPU use by the thread occurred if it later
     serviced a connection that had to wait for a table lock.
     (Bug#25966 (http://bugs.mysql.com/25966))

   * `VIEW' restrictions were applied to `SELECT' statements after a
     `CREATE VIEW' statement failed, as though the `CREATE' had
     succeeded.  (Bug#25897 (http://bugs.mysql.com/25897))

   * Several deficiencies in resolution of column names for `INSERT ...
     SELECT' statements were corrected.  (Bug#25831
     (http://bugs.mysql.com/25831))

   * Inserting `utf8' data into a `TEXT' column that used a single-byte
     character set could result in spurious warnings about truncated
     data.  (Bug#25815 (http://bugs.mysql.com/25815))

   * On Windows, debug builds of `mysqld' could fail with heap
     assertions.  (Bug#25765 (http://bugs.mysql.com/25765))

   * In certain cases it could happen that deleting a row corrupted an
     `RTREE' index. This affected indexes on spatial columns.
     (Bug#25673 (http://bugs.mysql.com/25673))

   * Using `mysqlbinlog' on a binary log would crash if there were a
     large number of row-based events related to a single statement.
     (Bug#25628 (http://bugs.mysql.com/25628))

   * Expressions involving `SUM()', when used in an `ORDER BY' clause,
     could lead to out-of-order results.  (Bug#25376
     (http://bugs.mysql.com/25376))

   * Use of a `GROUP BY' clause that referred to a stored function
     result together with `WITH ROLLUP' caused incorrect results.
     (Bug#25373 (http://bugs.mysql.com/25373))

   * A stored procedure that made use of cursors failed when the
     procedure was invoked from a stored function.  (Bug#25345
     (http://bugs.mysql.com/25345))

   * On Windows, the server exhibited a file-handle leak after reaching
     the limit on the number of open file descriptors.  (Bug#25222
     (http://bugs.mysql.com/25222))

   * The `REPEAT()' function did not allow a column name as the COUNT
     parameter.  (Bug#25197 (http://bugs.mysql.com/25197))

   * Duplicating the usage of a user variable in a stored procedure or
     trigger would not be replicated correctly to the slave.
     (Bug#25167 (http://bugs.mysql.com/25167))

   * A reference to a non-existent column in the `ORDER BY' clause of
     an `UPDATE ... ORDER BY' statement could cause a server crash.
     (Bug#25126 (http://bugs.mysql.com/25126))

   * A view on a join is insertable for `INSERT' statements that store
     values into only one table of the join.  However, inserts were
     being rejected if the inserted-into table was used in a self-join
     because MySQL incorrectly was considering the insert to modify
     multiple tables of the view.  (Bug#25122
     (http://bugs.mysql.com/25122))

   * Creating a table with latin characters in the name caused the
     output of `SHOW FULL TABLES' to have `ERROR' for the table type.
     (Bug#25081 (http://bugs.mysql.com/25081))

   * MySQL would not compile when configured using
     `--without-query-cache'.  (Bug#25075 (http://bugs.mysql.com/25075))

   * It was not possible to use XPath keywords as tag names for
     expressions used in the `ExtractValue()' function.  (Bug#24747
     (http://bugs.mysql.com/24747))

   * Increasing the width of a `DECIMAL' column could cause column
     values to be changed.  (Bug#24558 (http://bugs.mysql.com/24558))

   * IF(EXPR, UNSIGNED_EXPR, UNSIGNED_EXPR) was evaluated to a signed
     result, not unsigned. This has been corrected. The fix also
     affects constructs of the form `IS [NOT] {TRUE|FALSE}', which were
     transformed internally into `IF()' expressions that evaluated to a
     signed result.

     For existing views that were defined using `IS [NOT] {TRUE|FALSE}'
     constructs, there is a related implication. The definitions of
     such views were stored using the `IF()' expression, not the
     original construct. This is manifest in that `SHOW CREATE VIEW'
     shows the transformed `IF()' expression, not the original one.
     Existing views will evaluate correctly after the fix, but if you
     want `SHOW CREATE VIEW' to display the original construct, you
     must drop the view and re-create it using its original definition.
     New views will retain the construct in their definition.
     (Bug#24532 (http://bugs.mysql.com/24532))

   * `DROP TRIGGER' statements would not be filtered on the slave when
     using the `replication-wild-do-table' option.  (Bug#24478
     (http://bugs.mysql.com/24478))

   * For `INSERT ... ON DUPLICATE KEY UPDATE' statements where some
     `AUTO_INCREMENT' values were generated automatically for inserts
     and some rows were updated, one auto-generated value was lost per
     updated row, leading to faster exhaustion of the range of the
     `AUTO_INCREMENT' column.

     Because the original problem can affect replication (different
     values on master and slave), it is recommended that the master and
     its slaves be upgraded to the current version.  (Bug#24432
     (http://bugs.mysql.com/24432))

   * `SHOW ENGINE MUTEX STATUS' failed to produce an `Unknown table
     engine' error.

     See *Note show-engine::.  (Bug#24392 (http://bugs.mysql.com/24392))

   * A user-defined variable could be assigned an incorrect value if a
     temporary table was employed in obtaining the result of the query
     used to determine its value.  (Bug#24010
     (http://bugs.mysql.com/24010))

   * `mysqlimport' used a variable of the wrong type for the
     `--use-threads' option, which could cause a crash on some
     architectures.  (Bug#23814 (http://bugs.mysql.com/23814))

   * Queries that used a temporary table for the outer query when
     evaluating a correlated subquery could return incorrect results.
     (Bug#23800 (http://bugs.mysql.com/23800))

   * Replication between master and slave would infinitely retry binary
     log transmission where the `max_allowed_packet' on the master was
     larger than that on the slave if the size of the transfer was
     between these two values.  (Bug#23775
     (http://bugs.mysql.com/23775))

   * On Windows, debug builds of `mysqlbinlog' could fail with a memory
     error.  (Bug#23736 (http://bugs.mysql.com/23736))

   * When using certain server SQL modes, the `mysql.proc' table was
     not created by `mysql_install_db'.  (Bug#23669
     (http://bugs.mysql.com/23669))

   * `DOUBLE' values such as `20070202191048.000000' were being treated
     as illegal arguments by `WEEK()'.  (Bug#23616
     (http://bugs.mysql.com/23616))

   * The server could crash if two or more threads initiated query
     cache resize operation at moments very close in time.  (Bug#23527
     (http://bugs.mysql.com/23527))

   * `NOW()' returned the wrong value in statements executed at server
     startup with the `--init-file' option.  (Bug#23240
     (http://bugs.mysql.com/23240))

   * Setting the `slow_query_log_file' system variable caused log
     output to go tothe general log, not the slow query log.
     (Bug#23225 (http://bugs.mysql.com/23225))

   * When nesting stored procedures within a trigger on a table, a
     false dependency error was thrown when one of the nested
     procedures contained a `DROP TABLE' statement.  (Bug#22580
     (http://bugs.mysql.com/22580))

   * Instance Manager did not remove the angel PID file on a clean
     shutdown.  (Bug#22511 (http://bugs.mysql.com/22511))

   * `EXPLAIN EXTENDED' did not show `WHERE' conditions that were
     optimized away.  (Bug#22331 (http://bugs.mysql.com/22331))

   * `IN ((SUBQUERY))', `IN (((SUBQUERY)))', and so forth, are
     equivalent to `IN (SUBQUERY)', which is always interpreted as a
     table subquery (so that it is allowed to return more than one
     row). MySQL was treating the `over-parenthesized' subquery as a
     single-row subquery and rejecting it if it returned more than one
     row. This bug primarily affected automatically generated code
     (such as queries generated by Hibernate), because humans rarely
     write the over-parenthesized forms.  (Bug#21904
     (http://bugs.mysql.com/21904))

   * An `INSERT' trigger invoking a stored routine that inserted into a
     table other than the one on which the trigger was defined would
     fail with a `Table '...'  doesn't exist' referring to the second
     table when attempting to delete records from the first table.
     (Bug#21825 (http://bugs.mysql.com/21825))

   * `CURDATE()' is less than `NOW()', either when comparing `CURDATE()'
     directly (`CURDATE() < NOW()' is true) or when casting `CURDATE()'
     to `DATE' (`CAST(CURDATE() AS DATE) < NOW()' is true). However,
     storing `CURDATE()' in a `DATE' column and comparing ` COL_NAME <
     NOW()' incorrectly yielded false. This is fixed by comparing a
     `DATE' column as `DATETIME' for comparisons to a `DATETIME'
     constant.  (Bug#21103 (http://bugs.mysql.com/21103))

   * When a stored routine attempted to execute a statement accessing a
     nonexistent table, the error was not caught by the routine's
     exception handler.  (Bug#20713 (http://bugs.mysql.com/20713),
     Bug#8407 (http://bugs.mysql.com/8407))

   * For a stored procedure containing a `SELECT' statement that used a
     complicated join with an `ON' expression, the expression could be
     ignored during re-execution of the procedure, yielding an
     incorrect result.  (Bug#20492 (http://bugs.mysql.com/20492))

   * The conditions checked by the optimizer to allow use of indexes in
     `IN' predicate calculations were unnecessarily tight and were
     relaxed.  (Bug#20420 (http://bugs.mysql.com/20420))

   * When a `TIME_FORMAT()' expression was used as a column in a `GROUP
     BY' clause, the expression result was truncated.  (Bug#20293
     (http://bugs.mysql.com/20293))

   * The creation of MySQL system tables was not checked for by
     `mysql-test-run.pl'.  (Bug#20166 (http://bugs.mysql.com/20166))

   * For index reads, the `BLACKHOLE' engine did not return end-of-file
     (which it must because `BLACKHOLE' tables contain no rows), causing
     some queries to crash.  (Bug#19717 (http://bugs.mysql.com/19717))

   * For `EXPR IN(VALUE_LIST)', the result could be incorrect if
     `BIGINT UNSIGNED' values were used for EXPR or in the value list.
     (Bug#19342 (http://bugs.mysql.com/19342))

   * When attempting to call a stored procedure creating a table from a
     trigger on a table `tbl' in a database `db', the trigger failed
     with `ERROR 1146 (42S02): Table 'db.tbl' doesn't exist'. However,
     the actual reason that such a trigger fails is due to the fact
     that `CREATE TABLE' causes an implicit `COMMIT', and so a trigger
     cannot invoke a stored routine containing this statement. A
     trigger which does so now fails with `ERROR 1422 (HY000): Explicit
     or implicit commit is not allowed in stored function or trigger',
     which makes clear the reason for the trigger's failure.
     (Bug#18914 (http://bugs.mysql.com/18914))

   * While preparing prepared statements, the server acquired
     unnecessary table write locks.  (Bug#18326
     (http://bugs.mysql.com/18326))

   * The update columns for `INSERT ... SELECT ... ON DUPLICATE KEY
     UPDATE' could be assigned incorrect values if a temporary table
     was used to evaluate the `SELECT'.  (Bug#16630
     (http://bugs.mysql.com/16630))

   * For `SUBSTRING()' evaluation using a temporary table, when
     `SUBSTRING()' was used on a LONGTEXT column, the `max_length'
     metadata value of the result was incorrectly calculated and set to
     0.  Consequently, an empty string was returned instead of the
     correct result.  (Bug#15757 (http://bugs.mysql.com/15757))

   * Loading data using `LOAD DATA INFILE' may not replicate correctly
     (due to character set incompatibilities) if the
     `character_set_database' variable is set before the data is loaded.
     (Bug#15126 (http://bugs.mysql.com/15126))

   * User defined variables used within stored procedures and triggers
     are not replicated correctly when operating in statement-based
     replication mode.  (Bug#14914 (http://bugs.mysql.com/14914),
     Bug#20141 (http://bugs.mysql.com/20141))

   * Local variables in stored routines or triggers, when declared as
     the `BIT' type, were interpreted as strings.  (Bug#12976
     (http://bugs.mysql.com/12976))

   * For some operations, system tables in the `mysql' database must be
     accessed. For example, the `HELP' statement requires the contents
     of the server-side help tables, and `CONVERT_TZ()' might need to
     read the time zone tables. However, to perform such operations
     while a `LOCK TABLES' statement is in effect, the server required
     you to also lock the requisite system tables explicitly or a lock
     error occurred:

          mysql> LOCK TABLE t1 READ;
          Query OK, 0 rows affected (0.02 sec)
          mysql> HELP HELP;
          ERROR 1100 (HY000) at line 4: Table 'help_topic' was not
          locked with LOCK TABLES

     Now, the server implicitly locks the system tables for reading as
     necessary so that you need not lock them explicitly. These tables
     are treated as just described:

          mysql.help_category
          mysql.help_keyword
          mysql.help_relation
          mysql.help_topic
          mysql.proc
          mysql.time_zone
          mysql.time_zone_leap_second
          mysql.time_zone_name
          mysql.time_zone_transition
          mysql.time_zone_transition_type

     If you want to explicitly place a `WRITE' lock on any of those
     tables with a `LOCK TABLES' statement, the table must be the only
     one locked; no other table can be locked with the same statement.
     (Bug#9953 (http://bugs.mysql.com/9953))


File: manual.info,  Node: news-5-1-16,  Next: news-5-1-15,  Prev: news-5-1-17,  Up: news-5-1-x

C.1.14 Changes in MySQL 5.1.16 (26 February 2007)
-------------------------------------------------

This is a new Beta development release, fixing recently discovered bugs.

*Note*:

This Beta release, as any other pre-production release, should not be
installed on _production_ level systems or systems with critical data.
It is good practice to back up your data before installing any new
version of software.  Although MySQL has worked very hard to ensure a
high level of quality, protect your data by making a backup as you
would for any software beta release. Please refer to our bug database at
`http://bugs.mysql.com/' for more details about the individual bugs
fixed in this version.

*Note*:

After release, a trigger failure problem was found to have been
introduced. (Bug#27006 (http://bugs.mysql.com/27006)) Users affected by
this issue should upgrade to MySQL 5.1.17, which corrects the problem.

This section documents all changes and bug fixes that have been applied
since the last official MySQL release. If you would like to receive
more fine-grained and personalized _update alerts_ about fixes that are
relevant to the version and features you use, please consider
subscribing to _MySQL Enterprise_ (a commercial MySQL offering). For
more details please see `http://www.mysql.com/products/enterprise'.

Functionality added or changed:

   * *Cluster API*: *Incompatible Change*: The `AbortOption' type is
     now a member of the `NdbOperation' class; its values and behavior
     have also changed.  `NdbTransaction::AbortOption' can no longer be
     used, and applications written against the NDB API may need to be
     rewritten and recompiled to accomodate these changes. For more
     information about this change, see The `NdbOperation::AbortOption'
     Type
     (http://dev.mysql.com/doc/ndbapi/en/class-ndboperation-abortoption.html).

     This also affects the behavior of the `NdbTransaction::execute()'
     method, which now reports failure only if the transaction was
     actually aborted.  See `NdbTransaction::execute()'
     (http://dev.mysql.com/doc/ndbapi/en/class-ndbtransaction-execute.html),
     for more information.

   * *MySQL Cluster*: Previously, when a data node failed more than 8
     times in succession to start, this caused a forced shutdown of the
     cluster. Now, when a data node fails to start 7 consecutive times,
     the node will not start again until it is started with the
     `--initial' option, and a warning to this effect is written to the
     error log.  (Bug#25984 (http://bugs.mysql.com/25984))

   * *MySQL Cluster*: In the event that all cluster management and API
     nodes are configured with `ArbitrationRank=0', `ndb_mgmd' now
     issues the following warning when starting: `Cluster configuration
     warning: Neither MGM nor API nodes are configured with arbitrator,
     may cause complete cluster shutdown in case of host failure'.
     (Bug#23546 (http://bugs.mysql.com/23546))

   * *MySQL Cluster*: A number of new and more descriptive error
     messages covering transporter errors were added.  (Bug#22025
     (http://bugs.mysql.com/22025))

   * *MySQL Cluster*: A new configuration parameter
     `MemReportFrequency' allows for additional control of data node
     memory usage. Previously, only warnings at predetermined
     percentages of memory allocation were given; setting this
     parameter allows for that behavior to be overridden. For more
     information, see *Note mysql-cluster-ndbd-definition::.

   * *Cluster API*: A new `ndb_mgm_get_clusterlog_loglevel()' function
     was added to the MGM API.

     For more information, see `ndb_mgm_get_clusterlog_loglevel()'
     (http://dev.mysql.com/doc/ndbapi/en/ndb-mgm-get-clusterlog-loglevel.html).

   * The `localhost' anonymous user account created during MySQL
     installation on Windows now has no global privileges. Formerly
     this account had all global privileges. For operations that
     require global privileges, the `root' account can be used instead.
     (Bug#24496 (http://bugs.mysql.com/24496))

   * In the `INFORMATION_SCHEMA' `REFERENTIAL_CONSTRAINTS' table, the
     `UNIQUE_CONSTRAINT_NAME' column incorrectly named the referenced
     table. Now it names the referenced constraint, and a new column,
     `REFERENCED_TABLE_NAME', names the referenced table.  (Bug#21713
     (http://bugs.mysql.com/21713))

   * `RAND()' now allows non-constant initializers (such as a column
     name) as its argument. In this case, the seed is initialized with
     the value for each invocation of `RAND()'. (One implication of
     this is that for equal argument values, `RAND()' will return the
     same value each time.)  (Bug#6172 (http://bugs.mysql.com/6172))

   * Added the `--auto-generate-sql-load-type' and
     `--auto-generate-sql-write-number' options for `mysqlslap'.

   * The bundled yaSSL library was upgraded to version 1.5.8.

Bugs fixed:

   * *Security Fix*: Using an `INFORMATION_SCHEMA' table with `ORDER
     BY' in a subquery could cause a server crash.

     We would like to thank Oren Isacson of Flowgate Security
     Consulting and Stefan Streichsbier of SEC Consult for informing us
     of this problem.  (Bug#24630 (http://bugs.mysql.com/24630),
     Bug#26556 (http://bugs.mysql.com/26556), CVE-2007-1420
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-1420))

   * *Partitioning*: *MySQL Cluster*: A query with an `IN' clause
     against an `NDB' table employing explicit user-defined
     partitioning did not always return all matching rows.  (Bug#25821
     (http://bugs.mysql.com/25821))

   * *MySQL Cluster*: An inadvertent use of unaligned data caused
     `ndb_restore' to fail on some 64-bit platforms, including Sparc
     and Itanium-2.  (Bug#26739 (http://bugs.mysql.com/26739))

   * *MySQL Cluster*: The InvalidUndoBufferSize error used the same
     error code (763) as the IncompatibleVersions error.
     InvalidUndoBufferSize now uses its own error code (779).
     (Bug#26490 (http://bugs.mysql.com/26490))

   * *MySQL Cluster*: The failure of a data node when restarting it with
     `--initial' could lead to failures of subsequent data node
     restarts.  (Bug#26481 (http://bugs.mysql.com/26481))

   * *MySQL Cluster*: Takeover for local checkpointing due to multiple
     failures of master nodes was sometimes incorrectly handled.
     (Bug#26457 (http://bugs.mysql.com/26457))

   * *MySQL Cluster*: The `LockPagesInMainMemory' parameter was not
     read until after distributed communication had already started
     between cluster nodes. When the value of this parameter was `1',
     this could sometimes result in data node failure due to missed
     heartbeats.  (Bug#26454 (http://bugs.mysql.com/26454))

   * *MySQL Cluster*: Under some circumstances, following the restart
     of a management node, all data nodes would connect to it normally,
     but some of them subsequently failed to log any events to the
     management node.  (Bug#26293 (http://bugs.mysql.com/26293))

   * *MySQL Cluster*: Condition pushdown did not work with prepared
     statements.  (Bug#26225 (http://bugs.mysql.com/26225))

   * *MySQL Cluster*: (Replication): Under some circumstances, the
     binlog thread could shut down while the slave SQL thread was still
     using it.  (Bug#26015 (http://bugs.mysql.com/26015), Bug#26019
     (http://bugs.mysql.com/26019))

   * *MySQL Cluster*: A memory leak could cause problems during a node
     or cluster shutdown or failure.  (Bug#25997
     (http://bugs.mysql.com/25997))

   * *MySQL Cluster*: No appropriate error message was provided when
     there was insufficient REDO log file space for the cluster to
     start.  (Bug#25801 (http://bugs.mysql.com/25801))

   * *MySQL Cluster*: An `UPDATE' using an `IN' clause on an `NDB'
     table on which there was a trigger caused `mysqld' to crash.
     (Bug#25522 (http://bugs.mysql.com/25522))

   * *MySQL Cluster*: A memory allocation failure in `SUMA' (the
     cluster Subscription Manager) could cause the cluster to crash.
     (Bug#25239 (http://bugs.mysql.com/25239))

   * *MySQL Cluster*: The `ndb_size.tmpl' file (necessary for using the
     `ndb_size.pl' script) was missing from binary distributions.
     (Bug#24191 (http://bugs.mysql.com/24191))

   * *MySQL Cluster*: The message `Error 0 in readAutoIncrementValue():
     no Error' was written to the error log whenever `SHOW TABLE
     STATUS' was performed on a Cluster table that did not have an
     `AUTO_INCREMENT' column.

     *Note*:

     This improves on and supersedes an earlier fix that was made for
     this issue in MySQL 5.1.12.

     (Bug#21033 (http://bugs.mysql.com/21033))

   * *MySQL Cluster*: When a node failed due to there being
     insufficient disk space to perform a local checkpoint, there was
     no indication that this was the source of the problem. Such a
     condition now produces an appropriate error message.  (Bug#20121
     (http://bugs.mysql.com/20121))

   * *MySQL Cluster*: (Replication): The error message `Last_Errno:
     4294967295, Error in Write_rows event' now supplies a valid error
     code.  (Bug#19896 (http://bugs.mysql.com/19896))

   * *MySQL Cluster*: In the event that cluster backup parameters such
     as `BackupWriteSize' were incorrectly set, no appropriate error
     was issued to indicate that this was the case.  (Bug#19146
     (http://bugs.mysql.com/19146))

   * *Cluster API*: *Disk Data*: A delete and a read performed in the
     same operation could cause one or more data nodes to crash. This
     could occur when the operation affected more than 5 columns
     concurrently, or when one or more of the columns was of the
     `VARCHAR' type and was stored on disk.  (Bug#25794
     (http://bugs.mysql.com/25794))

   * *Cluster API*: After defining a delete operation (using
     `NdbOperation::deleteTuple()') on a nonexistent primary key of a
     table having a `BLOB' or `TEXT' column, invoking
     `NdbTransaction::execute()' caused the calling application to
     enter an endless loop rather than raising an error.

     This issue also affected `ndb_restore'; when restoring tables
     containing `BLOB' or `TEXT' columns, this could cause it to consume
     all available memory and then crash.  (Bug#24028
     (http://bugs.mysql.com/24028)) See also Bug#27308
     (http://bugs.mysql.com/27308), Bug#30177
     (http://bugs.mysql.com/30177)

   * *Cluster API*: `libndbclient.so' was not versioned.  (Bug#13522
     (http://bugs.mysql.com/13522))

   * Using `ORDER BY' or `GROUP BY' could yield different results when
     selecting from a view and selecting from the underlying table.
     (Bug#26209 (http://bugs.mysql.com/26209))

   * `DISTINCT' queries that were executed using a loose scan for an
     `InnoDB' table that had been emptied caused a server crash.
     (Bug#26159 (http://bugs.mysql.com/26159))

   * A `WHERE' clause that used `BETWEEN' for `DATETIME' values could
     be treated differently for a `SELECT' and a view defined as that
     `SELECT'.  (Bug#26124 (http://bugs.mysql.com/26124))

   * Collation for `LEFT JOIN' comparisons could be evaluated
     incorrectly, leading to improper query results.  (Bug#26017
     (http://bugs.mysql.com/26017))

   * The `WITH CHECK OPTION' clause for views was ignored for updates
     of multiple-table views when the updates could not be performed on
     fly and the rows to update had to be put into temporary tables
     first.  (Bug#25931 (http://bugs.mysql.com/25931))

   * `LOAD DATA INFILE' did not work with pipes.  (Bug#25807
     (http://bugs.mysql.com/25807))

   * The `SEC_TO_TIME()' and `QUARTER()' functions sometimes did not
     handle `NULL' values correctly.  (Bug#25643
     (http://bugs.mysql.com/25643))

   * View definitions that used the `!' operator were treated as
     containing the `NOT' operator, which has a different precedence
     and can produce different results. .  (Bug#25580
     (http://bugs.mysql.com/25580))

   * An error in the name resolution of nested `JOIN ...  USING'
     constructs was corrected.  (Bug#25575
     (http://bugs.mysql.com/25575))

   * `GROUP BY' and `DISTINCT' did not group `NULL' values for columns
     that have a `UNIQUE' index. .  (Bug#25551
     (http://bugs.mysql.com/25551))

   * The `--with-readline' option for `configure' did not work for
     commercial source packages, but no error message was printed to
     that effect. Now a message is printed.  (Bug#25530
     (http://bugs.mysql.com/25530))

   * A yaSSL program named `test' was installed, causing conflicts with
     the `test' system utility. It is no longer installed.  (Bug#25417
     (http://bugs.mysql.com/25417))

   * For a `UNIQUE' index containing many `NULL' values, the optimizer
     would prefer the index for `COL IS NULL' conditions over other
     more selective indexes. .  (Bug#25407
     (http://bugs.mysql.com/25407))

   * An `AFTER UPDATE' trigger on an `InnoDB' table with a composite
     primary key caused the server to crash.  (Bug#25398
     (http://bugs.mysql.com/25398))

   * Passing a `NULL' value to a user-defined function from within a
     stored procedure crashes the server.  (Bug#25382
     (http://bugs.mysql.com/25382))

   * `perror' crashed on some platforms due to failure to handle a
     `NULL' pointer.  (Bug#25344 (http://bugs.mysql.com/25344))

   * `mysql.server stop' timed out too quickly (35 seconds) waiting for
     the server to exit. Now it waits up to 15 minutes, to ensure that
     the server exits.  (Bug#25341 (http://bugs.mysql.com/25341))

   * A query that contained an `EXIST' subquery with a `UNION' over
     correlated and uncorrelated `SELECT' queries could cause the
     server to crash.  (Bug#25219 (http://bugs.mysql.com/25219))

   * *Note `mysql_kill()': mysql-kill. caused a server crash when used
     on an SSL connection.  (Bug#25203 (http://bugs.mysql.com/25203))

   * yaSSL was sensitive to the presence of whitespace at the ends of
     lines in PEM-encoded certificates, causing a server crash.
     (Bug#25189 (http://bugs.mysql.com/25189))

   * A query with `ORDER BY' and `GROUP BY' clauses where the `ORDER BY'
     clause had more elements than the `GROUP BY' clause caused a
     memory overrun leading to a crash of the server.  (Bug#25172
     (http://bugs.mysql.com/25172))

   * Use of `ON DUPLICATE KEY UPDATE' defeated the usual restriction
     against inserting into a join-based view unless only one of the
     underlying tables is used.  (Bug#25123
     (http://bugs.mysql.com/25123))

   * `ALTER TABLE ... ENABLE KEYS' acquired a global lock, preventing
     concurrent execution of other statements that use tables. .
     (Bug#25044 (http://bugs.mysql.com/25044))

   * `OPTIMIZE TABLE' caused a race condition in the I/O cache.
     (Bug#25042 (http://bugs.mysql.com/25042))

   * A return value of `-1' from user-defined handlers was not handled
     well and could result in conflicts with server code.  (Bug#24987
     (http://bugs.mysql.com/24987))

   * Certain joins using `Range checked for each record' in the query
     execution plan could cause the server to crash.  (Bug#24776
     (http://bugs.mysql.com/24776))

   * `ALTER TABLE' caused loss of `CASCADE' clauses for `InnoDB' tables.
     (Bug#24741 (http://bugs.mysql.com/24741))

   * If an `ORDER BY' or `GROUP BY' list included a constant expression
     being optimized away and, at the same time, containing single-row
     subselects that returned more that one row, no error was reported.
     If a query required sorting by expressions containing single-row
     subselects that returned more than one row, execution of the query
     could cause a server crash.  (Bug#24653
     (http://bugs.mysql.com/24653))

   * For `ALTER TABLE', using `ORDER BY EXPRESSION' could cause a
     server crash. Now the `ORDER BY' clause allows only column names
     to be specified as sort criteria (which was the only documented
     syntax, anyway).  (Bug#24562 (http://bugs.mysql.com/24562))

   * Within stored routines or prepared statements, inconsistent
     results occurred with multiple use of `INSERT ... SELECT ... ON
     DUPLICATE KEY UPDATE' when the `ON DUPLICATE KEY UPDATE' clause
     erroneously tried to assign a value to a column mentioned only in
     its `SELECT' part.  (Bug#24491 (http://bugs.mysql.com/24491))

   * Expressions of the form `(a, b) IN (SELECT a, MIN(b) FROM t GROUP
     BY a)' could produce incorrect results when column `a' of table `t'
     contained `NULL' values while column `b' did not.  (Bug#24420
     (http://bugs.mysql.com/24420))

   * If a prepared statement accessed a view, access to the tables
     listed in the query after that view was checked in the security
     context of the view.  (Bug#24404 (http://bugs.mysql.com/24404))

   * A nested query on a partitioned table returned fewer records than
     on the corresponding non-partitioned table, when the subquery
     affected more than one partition.  (Bug#24186
     (http://bugs.mysql.com/24186))

   * Expressions of the form `(a, b) IN (SELECT c, d ...)' could
     produce incorrect results if `a', `b', or both were `NULL'.
     (Bug#24127 (http://bugs.mysql.com/24127))

   * Queries that evaluate `NULL IN (SELECT ... UNION SELECT ...)'
     could produce an incorrect result (`FALSE' instead of `NULL').
     (Bug#24085 (http://bugs.mysql.com/24085))

   * Some `UPDATE' statements were slower than in previous versions
     when the search key could not be converted to a valid value for
     the type of the search column.  (Bug#24035
     (http://bugs.mysql.com/24035))

   * `ISNULL(DATE(NULL))' and `ISNULL(CAST(NULL AS DATE))' erroneously
     returned false.  (Bug#23938 (http://bugs.mysql.com/23938))

   * Within a stored routine, accessing a declared routine variable
     with `PROCEDURE ANALYSE()' caused a server crash.  (Bug#23782
     (http://bugs.mysql.com/23782))

   * For an `InnoDB' table with any `ON DELETE' trigger, `TRUNCATE
     TABLE' mapped to `DELETE' and activated triggers. Now a fast
     truncation occurs and triggers are not activated. .

     *Important*:

     As a result of this fix, `TRUNCATE TABLE' now requires the `DROP'
     privilege rather than the `DELETE' privilege.

     (Bug#23556 (http://bugs.mysql.com/23556))

   * With `ONLY_FULL_GROUP_BY' enables, the server was too strict: Some
     expressions involving only aggregate values were rejected as
     non-aggregate (for example, `MAX(a)' - `MIN(a)').  (Bug#23417
     (http://bugs.mysql.com/23417))

   * The arguments to the `ENCODE()' and the `DECODE()' functions were
     not printed correctly, causing problems in the output of `EXPLAIN
     EXTENDED' and in view definitions.  (Bug#23409
     (http://bugs.mysql.com/23409))

   * Some queries against `INFORMATION_SCHEMA' that used subqueries
     failed. .  (Bug#23299 (http://bugs.mysql.com/23299))

   * `readline' detection did not work correctly on NetBSD.  (Bug#23293
     (http://bugs.mysql.com/23293))

   * The number of `setsockopt()' calls performed for reads and writes
     to the network socket was reduced to decrease system call overhead.
     (Bug#22943 (http://bugs.mysql.com/22943))

   * Storing values specified as hexadecimal values 64 or more bits
     long in `BIT(64)', `BIGINT', or `BIGINT UNSIGNED' columns did not
     raise any warning or error if the value was out of range.
     (Bug#22533 (http://bugs.mysql.com/22533))

   * Type conversion errors during formation of index search conditions
     were not correctly checked, leading to incorrect query results.
     (Bug#22344 (http://bugs.mysql.com/22344))

   * For the `IF()' and `COALESCE()' function and `CASE' expressions,
     large unsigned integer values could be mishandled and result in
     warnings.  (Bug#22026 (http://bugs.mysql.com/22026))

   * Inserting `DEFAULT' into a column with no default value could
     result in garbage in the column. Now the same result occurs as
     when inserting `NULL' into a `NOT NULL' column.  (Bug#20691
     (http://bugs.mysql.com/20691))

   * Indexes disabled with `ALTER TABLE ... DISABLE KEYS' could in some
     cases be used by specifying `FORCE INDEX'.  (Bug#20604
     (http://bugs.mysql.com/20604))

   * If a duplicate key value was present in the table, `INSERT ... ON
     DUPLICATE KEY UPDATE' reported a row count indicating that a
     record was updated, even when no record actually changed due to
     the old and new values being the same. Now it reports a row count
     of zero.  (Bug#19978 (http://bugs.mysql.com/19978)) See also
     Bug#27006 (http://bugs.mysql.com/27006), Bug#27033
     (http://bugs.mysql.com/27033), Bug#27210
     (http://bugs.mysql.com/27210)

   * `ORDER BY' values of the `DOUBLE' or `DECIMAL' types could change
     the result returned by a query.  (Bug#19690
     (http://bugs.mysql.com/19690))

   * The `readline' library wrote to uninitialized memory, causing
     `mysql' to crash.  (Bug#19474 (http://bugs.mysql.com/19474))

   * Use of already freed memory caused SSL connections to hang forever.
     (Bug#19209 (http://bugs.mysql.com/19209))

   * The server might fail to use an appropriate index for `DELETE'
     when `ORDER BY', `LIMIT', and a non-restricting `WHERE' are
     present.  (Bug#17711 (http://bugs.mysql.com/17711))

   * The optimizer used a filesort rather than a `const' table read in
     some cases when the latter was possible.  (Bug#16590
     (http://bugs.mysql.com/16590))

   * To enable installation of MySQL RPMs on Linux systems running RHEL
     4 (which includes SE-Linux) additional information was provided to
     specify some actions that are allowed to the MySQL binaries.
     (Bug#12676 (http://bugs.mysql.com/12676))

   * `CONNECTION' is no longer treated as a reserved word.  (Bug#12204
     (http://bugs.mysql.com/12204))

   * The presence of `ORDER BY' in a view definition prevented the
     `MERGE' algorithm from being used to resolve the view even if
     nothing else in the definition required the `TEMPTABLE' algorithm.
     (Bug#12122 (http://bugs.mysql.com/12122))

   * If a slave server closed its relay log (for example, due to an
     error during log rotation), the I/O thread did not recognize this
     and still tried to write to the log, causing a server crash.
     (Bug#10798 (http://bugs.mysql.com/10798))


File: manual.info,  Node: news-5-1-15,  Next: news-5-1-14,  Prev: news-5-1-16,  Up: news-5-1-x

C.1.15 Changes in MySQL 5.1.15 (25 January 2007)
------------------------------------------------

This is a new Beta development release, fixing recently discovered bugs.

*Note*:

This Beta release, as any other pre-production release, should not be
installed on _production_ level systems or systems with critical data.
It is good practice to back up your data before installing any new
version of software.  Although MySQL has worked very hard to ensure a
high level of quality, protect your data by making a backup as you
would for any software beta release. Please refer to our bug database at
`http://bugs.mysql.com/' for more details about the individual bugs
fixed in this version.

This section documents all changes and bug fixes that have been applied
since the last official MySQL release. If you would like to receive
more fine-grained and personalized _update alerts_ about fixes that are
relevant to the version and features you use, please consider
subscribing to _MySQL Enterprise_ (a commercial MySQL offering). For
more details please see `http://www.mysql.com/products/enterprise'.

Functionality added or changed:

   * *Incompatible Change*: *MySQL Cluster*: The
     `LockPagesInMainMemory' configuration parameter has changed its
     type and possible values. For more information, see `
     LockPagesInMainMemory '.

     *Important*:

     The values `true' and `false' are no longer accepted for this
     parameter. If you were using this parameter and had it set to
     `false' in a previous release, you must change it to `0'. If you
     had this parameter set to `true', you should instead use `1' to
     obtain the same behavior as previously, or `2' to take advantage
     of new functionality introduced with this release, as described in
     the section cited above.

     (Bug#25686 (http://bugs.mysql.com/25686))

   * *Incompatible Change*: `InnoDB' rolls back only the last statement
     on a transaction timeout. A new option,
     `--innodb_rollback_on_timeout', causes `InnoDB' to abort and roll
     back the entire transaction if a transaction timeout occurs (the
     same behavior as in MySQL 5.0.13 and earlier).  (Bug#24200
     (http://bugs.mysql.com/24200))

   * *Incompatible Change*: Previously, the `DATE_FORMAT()' function
     returned a binary string. Now it returns a string with a character
     set and collation given by `character_set_connection' and
     `collation_connection' so that it can return month and weekday
     names containing non-ASCII characters.  (Bug#22646
     (http://bugs.mysql.com/22646))

   * *Incompatible Change*: The following conditions apply to enabling
     the `read_only' system variable:

        * If you attempt to enable `read_only' while you have any
          explicit locks (acquired with `LOCK TABLES' or have a pending
          transaction, an error will occur.

        * If other clients hold explicit table locks or have pending
          transactions, the attempt to enable `read_only' blocks until
          the locks are released and the transactions end. While the
          attempt to enable `read_only' is pending, requests by other
          clients for table locks or to begin transactions also block
          until `read_only' has been set.

        * `read_only' can be enabled while you hold a global read lock
          (acquired with `FLUSH TABLES WITH READ LOCK') because that
          does not involve table locks.

     Previously, the attempt to enable `read_only' would return
     immediately even if explicit locks or transactions were pending,
     so some data changes could occur for statements executing in the
     server at the same time.  (Bug#22009
     (http://bugs.mysql.com/22009), Bug#11733
     (http://bugs.mysql.com/11733))

   * *Important Change*: When using `MERGE' tables the definition of the
     `MERGE' table and the `MyISAM' tables are checked each time the
     tables are opened for access (including any `SELECT' or `INSERT'
     statement. Each table is compared for column order, types, sizes
     and associated. If there is a difference in any one of the tables
     then the statement will fail.

   * *Important Change*: Previously, duplicate-key errors were
     indicated by the `ER_DUP_ENTRY' error code (1062). This code is no
     longer used. Instead, the server returns
     `ER_DUP_ENTRY_WITH_KEY_NAME' (1582), and the error message
     indicates the name of the index for which the duplicate occurred.
     Applications that test for duplicate keys should look for both
     error codes if they need to be compatible with current and older
     servers.

     See also Bug#28842 (http://bugs.mysql.com/28842)

   * *MySQL Cluster*: The `NDB' storage engine could leak memory during
     file operations.  (Bug#21858 (http://bugs.mysql.com/21858))

   * On Unix, when searching the standard locations for option files,
     MySQL programs now also look for /etc/mysql/my.cnf after checking
     for /etc/my.cnf and before checking the remaining locations.
     (Bug#25104 (http://bugs.mysql.com/25104))

   * The default value of the `max_connections' variable has been
     increased to 151 in order that Websites running on Apache and
     using MySQL will not have more processes trying to access MySQL
     than the default number of connections available.

     (The maximum number of Apache processes is determined by the
     Apache `MaxClient', which defaults to 256, but is usually set to
     150 in the `httpd.conf' commonly distributed with Apache. For more
     information about `MaxClient', see
     `http://httpd.apache.org/docs/2.2/mod/mpm_common.html#maxclients'.)
     (Bug#23883 (http://bugs.mysql.com/23883))

   * The `Com_create_user' status variable was added (for counting
     `CREATE USER' statements).  (Bug#22958
     (http://bugs.mysql.com/22958))

   * The `--memlock' option relies on system calls that are unreliable
     on some operating systems. If a crash occurs, the server now
     checks whether `--memlock' was specified and if so issues some
     information about possible workarounds.  (Bug#22860
     (http://bugs.mysql.com/22860))

   * The (undocumented) `UNIQUE_USERS()' and `GROUP_UNIQUE_USERS()'
     functions were removed.  (Bug#22687 (http://bugs.mysql.com/22687))

   * Partitioning of tables using the `FEDERATED' storage engine is no
     longer permitted. Attempting to create such a table or to modify
     an existing table so that is uses both partitioning and
     `FEDERATED' now fails with an error.  (Bug#22451
     (http://bugs.mysql.com/22451))

   * The `--skip-thread-priority' option now is enabled by default for
     binary Mac OS X distributions. Use of thread priorities degrades
     performance on Mac OS X.  (Bug#18526 (http://bugs.mysql.com/18526))

   * Calling a non-deterministic stored routine when using
     statement-based replication now throws an error. Formerly,
     defining such a stored routine would cause an error to be thrown.
     (Bug#16456 (http://bugs.mysql.com/16456))

   * `read_only' can be enabled while you hold a global read lock
     (acquired with `FLUSH TABLES WITH READ LOCK') because that does
     not involve table locks.

   * The bundled yaSSL library was upgraded to version 1.5.0.

   * Remote servers for use with the `FEDERATED' storage engine now can
     be managed with the new `CREATE/ALTER/DROP SERVER' syntax.

   * Added the `--disable-grant-options' option to `configure'. If
     `configure' is run with this option, the `--bootstrap',
     `--skip-grant-tables', and `--init-file' options for `mysqld' are
     disabled and cannot be used. For Windows, the `configure.js'
     script recognizes the `DISABLE_GRANT_OPTIONS' flag, which has the
     same effect.

   * If other clients hold explicit table locks or have pending
     transactions, the attempt to enable `read_only' blocks until the
     locks are released and the transactions end.  While the attempt to
     enable `read_only' is pending, requests by other clients for table
     locks or to begin transactions also block until `read_only' has
     been set.

   * If you attempt to enable `read_only' while you have any explicit
     locks (acquired with `LOCK TABLES' or have a pending transaction,
     an error will occur.

Bugs fixed:

   * *Incompatible Change*: For `ENUM' columns that had enumeration
     values containing commas, the commas were mapped to `0xff'
     internally. However, this rendered the commas indistinguishable
     from true `0xff' characters in the values. This no longer occurs.
     However, the fix requires that you dump and reload any tables that
     have `ENUM' columns containing any true `0xff' values. Dump the
     tables using `mysqldump' with the current server before upgrading
     from a version of MySQL 5.1 older than 5.1.15 to version 5.1.15 or
     newer.  (Bug#24660 (http://bugs.mysql.com/24660))

   * *Partitioning*: *MySQL Cluster*: Non-32-bit, non-aligned columns
     were not handled correctly in explicitly partitioned `NDB' tables.
     (Bug#25587 (http://bugs.mysql.com/25587))

   * *MySQL Cluster*: It was not possible to create an `NDB' table with
     a key on two `VARCHAR' columns where both columns had a storage
     length in excess of 256.  (Bug#25746 (http://bugs.mysql.com/25746))

   * *MySQL Cluster*: Hosts in clusters with large numbers of nodes
     could experience excessive CPU usage while obtaining configuration
     data.  (Bug#25711 (http://bugs.mysql.com/25711))

   * *MySQL Cluster*: In some circumstances, shutting down the cluster
     could cause connected `mysqld' processes to crash.  (Bug#25668
     (http://bugs.mysql.com/25668))

   * *MySQL Cluster*: Some aggregate queries such as `SELECT COUNT(*)'
     performed a table scan on `NDB' tables rather than checking table
     statistics, causing such queries to perform much more slowly in
     MySQL Cluster 5.1 than in 5.0.  (Bug#25567
     (http://bugs.mysql.com/25567))

   * *MySQL Cluster*: Memory allocations for `TEXT' columns were
     calculated incorrectly, resulting in space being wasted and other
     issues.  (Bug#25562 (http://bugs.mysql.com/25562))

   * *MySQL Cluster*: The failure of a master node during a node
     restart could lead to a resource leak, causing later node failures.
     (Bug#25554 (http://bugs.mysql.com/25554))

   * *MySQL Cluster*: The failure of a node during a local checkpoint
     could lead to other node failures.  (Bug#25468
     (http://bugs.mysql.com/25468))

   * *MySQL Cluster*: (Replication): Connecting a `mysqld' to a cluster
     where not all nodes were running, starting the remaining cluster
     nodes, and then disconnecting from the cluster caused the `mysqld'
     process to crash.  (Bug#25387 (http://bugs.mysql.com/25387))

   * *MySQL Cluster*: A node shutdown occurred if the master failed
     during a commit.  (Bug#25364 (http://bugs.mysql.com/25364))

   * *MySQL Cluster*: Creating a non-unique index with the `USING HASH'
     clause silently created an ordered index instead of issuing a
     warning.  (Bug#24820 (http://bugs.mysql.com/24820))

   * *MySQL Cluster*: `ndb_config' failed when trying to use 2
     management servers and node IDs.  (Bug#23887
     (http://bugs.mysql.com/23887))

   * *MySQL Cluster*: When a data node was shut down using the
     management client `STOP' command, a connection event
     (`NDB_LE_Connected') was logged instead of a disconnection event
     (`NDB_LE_Disconnected').  (Bug#22773 (http://bugs.mysql.com/22773))

   * *MySQL Cluster*: The management server did not handle logging of
     node shutdown events correctly in certain cases.  (Bug#22013
     (http://bugs.mysql.com/22013))

   * *MySQL Cluster*: `SELECT' statements with a `BLOB' or `TEXT'
     column in the selected column list and a `WHERE' condition
     including a primary key lookup on a `VARCHAR' primary key produced
     empty result sets.  (Bug#19956 (http://bugs.mysql.com/19956))

   * *MySQL Cluster*: When stopping and restarting multiple data nodes,
     the last node to be restarted would sometimes hang in Phase 100.
     (Bug#19645 (http://bugs.mysql.com/19645))

   * *Disk Data*: Following 3 or more missed local checkpoints by a
     cluster node, a restart of the node caused incorrect undo
     information to be used for Disk Data tables.  (Bug#25636
     (http://bugs.mysql.com/25636))

   * *Disk Data*: `MEDIUMTEXT' columns of Disk Data tables were stored
     in memory rather than on disk, even if the columns were not
     indexed.  (Bug#25001 (http://bugs.mysql.com/25001))

   * *Disk Data*: Performing a node restart with a newly dropped Disk
     Data table could lead to failure of the node during the restart.
     (Bug#24917 (http://bugs.mysql.com/24917))

   * *Disk Data*: Changing a column specification or issuing a
     `TRUNCATE' statement on a Disk Data table caused the table to
     become an in-memory table.  (Bug#24667
     (http://bugs.mysql.com/24667), Bug#25296
     (http://bugs.mysql.com/25296))

   * *Disk Data*: When restoring from backup a cluster containing any
     Disk Data tables with hidden primary keys, a node failure resulted
     which could lead to a crash of the cluster.  (Bug#24166
     (http://bugs.mysql.com/24166))

   * *Disk Data*: Repeated `CREATE', `DROP', or `TRUNCATE' in various
     combinations with system restarts between these operations could
     lead to the eventual failure of a system restart.  (Bug#21948
     (http://bugs.mysql.com/21948))

   * *Disk Data*: Extents that should have been available for re-use
     following a `DROP TABLE' operation were not actually made
     available again until after the cluster had performed a local
     checkpoint.  (Bug#17605 (http://bugs.mysql.com/17605))

   * *Cluster Replication*: Certain errors in replication setups could
     lead to unexpected node failures.  (Bug#25755
     (http://bugs.mysql.com/25755))

   * *Cluster Replication*: Connecting an API node to the cluster
     during a node restart while performing database operations could
     cause the restarting node to fail.  (Bug#25329
     (http://bugs.mysql.com/25329))

   * *Cluster Replication*: Following a restart of the master cluster,
     the latest GCI was set to 0 upon reconnection to the slave.
     (Bug#21806 (http://bugs.mysql.com/21806))

   * *Cluster API*: Deletion of an `Ndb_cluster_connection' object took
     a very long time.  (Bug#25487 (http://bugs.mysql.com/25487))

   * *Cluster API*: Invoking the `NdbTransaction::execute()' method
     using execution type `Commit' and abort option `AO_IgnoreError'
     could lead to a crash of the transaction coordinator (`DBTC').
     (Bug#25090 (http://bugs.mysql.com/25090))

   * *Cluster API*: A unique index lookup on a non-existent tuple could
     lead to a data node timeout (error 4012).  (Bug#25059
     (http://bugs.mysql.com/25059))

   * *Cluster API*: When using the `NdbTransaction::execute()' method,
     a very long timeout (greater than 5 minutes) could result if the
     last data node being polled was disconnected from the cluster.
     (Bug#24949 (http://bugs.mysql.com/24949))

   * *Cluster API*: Due to an error in the computation of table
     fragment arrays, some transactions were not executed from the
     correct starting point.  (Bug#24914 (http://bugs.mysql.com/24914))

   * `mysqltest_embedded' crashed at startup.  (Bug#25890
     (http://bugs.mysql.com/25890))

   * Referencing an ambiguous column alias in an expression in the
     `ORDER BY' clause of a query caused the server to crash.
     (Bug#25427 (http://bugs.mysql.com/25427))

   * A number of issues were uncovered by Valgrind.  (Bug#25396
     (http://bugs.mysql.com/25396))

   * Using a view in combination with a `USING' clause caused column
     aliases to be ignored.  (Bug#25106 (http://bugs.mysql.com/25106))

   * A multiple-table `DELETE QUICK' could sometimes cause one of the
     affected tables to become corrupted.  (Bug#25048
     (http://bugs.mysql.com/25048))

   * An assertion failed incorrectly for prepared statements that
     contained a single-row uncorrelated subquery that was used as an
     argument of the `IS NULL' predicate.  (Bug#25027
     (http://bugs.mysql.com/25027))

   * In the `INFORMATION_SCHEMA.KEY_COLUMN_USAGE' table, the value
     displayed for the `REFERENCED_TABLE_NAME' column was the table
     name as encoded for disk storage, not the actual table name.
     (Bug#25026 (http://bugs.mysql.com/25026))

   * The `REPEAT()' function could return `NULL' when passed a column
     for the count argument.  (Bug#24947 (http://bugs.mysql.com/24947))

   * `mysql_upgrade' failed if the `--password' (or `-p') option was
     given.  (Bug#24896 (http://bugs.mysql.com/24896))

   * Accessing a fixed record format table with a crashed key
     definition results in server/`myisamchk' segmentation fault.
     (Bug#24855 (http://bugs.mysql.com/24855))

   * `mysqld_multi' and `mysqlaccess' looked for option files in `/etc'
     even if the `--sysconfdir' option for `configure' had been given
     to specify a different directory.  (Bug#24780
     (http://bugs.mysql.com/24780))

   * If there was insufficient memory available to `mysqld', this could
     sometimes cause the server to hang during startup.  (Bug#24751
     (http://bugs.mysql.com/24751))

   * Optimizations that are legal only for subqueries without tables
     and `WHERE' conditions were applied for any subquery without
     tables.  (Bug#24670 (http://bugs.mysql.com/24670))

   * Under certain rare circumstances, local checkpoints were not
     performed properly, leading to an inability to restart one or more
     data nodes.  (Bug#24664 (http://bugs.mysql.com/24664))

   * A workaround was implemented to avoid a race condition in the NPTL
     `pthread_exit()' implementation.  (Bug#24507
     (http://bugs.mysql.com/24507))

   * Under some circumstances, a `REORGANIZE PARTITION' statement could
     crash `mysqld'.  (Bug#24502 (http://bugs.mysql.com/24502))

   * `mysqltest' crashed with a stack overflow.  (Bug#24498
     (http://bugs.mysql.com/24498))

   * Using row-based replication to replicate to a table having at
     least one extra `BIT' column with a default value on the slave as
     compared to the master could cause the slave to fail.  (Bug#24490
     (http://bugs.mysql.com/24490))

   * Attempts to access a `MyISAM' table with a corrupt column
     definition caused a server crash.  (Bug#24401
     (http://bugs.mysql.com/24401))

   * `ALTER ENABLE KEYS' or `ALTER TABLE DISABLE KEYS' combined with
     another `ALTER TABLE' option other than `RENAME TO' did nothing.
     In addition, if ALTER TABLE was used on a table having disabled
     keys, the keys of the resulting table were enabled.  (Bug#24395
     (http://bugs.mysql.com/24395))

   * When opening a corrupted `.frm' file during a query, the server
     crashes.  (Bug#24358 (http://bugs.mysql.com/24358))

   * The `--extern' option for `mysql-test-run.pl' did not function
     correctly.  (Bug#24354 (http://bugs.mysql.com/24354))

   * Some joins in which one of the joined tables was a view could
     return erroneous results or crash the server.  (Bug#24345
     (http://bugs.mysql.com/24345))

   * The `mysql.server' script used the `source' command, which is less
     portable than the `.' command; it now uses `.' instead.
     (Bug#24294 (http://bugs.mysql.com/24294))

   * A view was not handled correctly if the `SELECT' part contained `
     `\Z' '.  (Bug#24293 (http://bugs.mysql.com/24293))

   * `mysql_install_db' did not create the `mysql.plugin' table if
     strict SQL mode was enabled.  (Bug#24270
     (http://bugs.mysql.com/24270))

   * A query using `WHERE UNSIGNED_COLUMN NOT IN ('NEGATIVE_VALUE')'
     could cause the server to crash.  (Bug#24261
     (http://bugs.mysql.com/24261))

   * `ALTER TABLE' statements that performed both `RENAME TO' and
     `{ENABLE|DISABLE} KEYS' operations caused a server crash.
     (Bug#24219 (http://bugs.mysql.com/24219))

   * When `SET PASSWORD' was written to the binary log double quotes
     were included in the statement. If the slave was running in with
     the server SQL mode set to `ANSI_QUOTES', then the event failed,
     which halted the replication process.  (Bug#24158
     (http://bugs.mysql.com/24158))

   * A `FETCH' statement using a cursor on a table which was not in the
     table cache could sometimes cause the server to crash.  (Bug#24117
     (http://bugs.mysql.com/24117))

   * Hebrew-to-Unicode conversion failed for some characters.
     Definitions for the following Hebrew characters (as specified by
     the ISO/IEC 8859-8:1999) were added: LEFT-TO-RIGHT MARK (LRM),
     RIGHT-TO-LEFT MARK (RLM) (Bug#24037 (http://bugs.mysql.com/24037))

   * On HP-UX, `mysqltest' (non-thread-safe) crashed due to being
     linked against a thread-safe `libmysys' library.  (Bug#23984
     (http://bugs.mysql.com/23984))

   * The server was built even when `configure' was run with the
     `--without-server' option.  (Bug#23973
     (http://bugs.mysql.com/23973)) See also Bug#32898
     (http://bugs.mysql.com/32898)

   * The MySQL 5.1.12 binaries for Windows were missing the
     `FEDERATED', `EXAMPLE', and `BLACKHOLE' storage engines.
     (Bug#23900 (http://bugs.mysql.com/23900))

   * `ROW_COUNT()' did not work properly as an argument to a stored
     procedure.  (Bug#23760 (http://bugs.mysql.com/23760))

   * When reading from the standard input on Windows, `mysqlbinlog'
     opened the input in text mode rather than binary mode and
     consequently misinterpreted some characters such as Control-Z.
     (Bug#23735 (http://bugs.mysql.com/23735))

   * A stored procedure, executed from a connection using a binary
     character set, and which wrote multibyte data, would write
     incorrectly escaped entries to the binary log. This caused syntax
     errors, and caused replication to fail.  (Bug#23619
     (http://bugs.mysql.com/23619), Bug#24492
     (http://bugs.mysql.com/24492))

   * `OPTIMIZE TABLE' tried to sort R-tree indexes such as spatial
     indexes, although this is not possible (see *Note
     optimize-table::).  (Bug#23578 (http://bugs.mysql.com/23578))

   * The row count for `MyISAM' tables was not updated properly,
     causing `SHOW TABLE STATUS' to report incorrect values.
     (Bug#23526 (http://bugs.mysql.com/23526))

   * The Instance Manager `DROP INSTANCE' command did not work.
     (Bug#23476 (http://bugs.mysql.com/23476))

   * User-defined variables could consume excess memory, leading to a
     crash caused by the exhaustion of resources available to the
     `MEMORY' storage engine, due to the fact that this engine is used
     by MySQL for variable storage and intermediate results of `GROUP
     BY' queries.  Where `SET' had been used, such a condition could
     instead give rise to the misleading error message `You may only
     use constant expressions with SET', rather than `Out of memory
     (Needed NNNNNN bytes)'.  (Bug#23443 (http://bugs.mysql.com/23443))

   * A table created with the `ROW_FORMAT = FIXED' table option lost
     the option if an index was added or dropped with `CREATE INDEX' or
     `DROP INDEX'.  (Bug#23404 (http://bugs.mysql.com/23404))

   * A deadlock could occur, with the server hanging on `Closing
     tables', with a sufficient number of concurrent `INSERT DELAYED',
     `FLUSH TABLES', and `ALTER TABLE' operations.  (Bug#23312
     (http://bugs.mysql.com/23312))

   * Accuracy was improved for comparisons between `DECIMAL' columns
     and numbers represented as strings.  (Bug#23260
     (http://bugs.mysql.com/23260))

   * The Instance Manager `STOP INSTANCE' command took too much time
     and caused Instance Manager to be unresponsive.  (Bug#23215
     (http://bugs.mysql.com/23215))

   * If there was insufficient memory to store or update a blob record
     in a `MyISAM' table then the table will marked as crashed.
     (Bug#23196 (http://bugs.mysql.com/23196))

   * A compressed `MyISAM' table that became corrupted could crash
     `myisamchk' and possibly the MySQL Server.  (Bug#23139
     (http://bugs.mysql.com/23139))

   * Using `CREATE TABLE ... SELECT' and rolling back the transaction
     would leave an empty table on the master, but the instructions
     would not be recorded in the binary log and therefore replicated
     to the slave. This would result in a difference between the master
     and slave databases. An implicit commit has been added to ensure
     consistency.  (Bug#22865 (http://bugs.mysql.com/22865))

   * `CREATE TABLE ... SELECT' statements were not rolled back
     correctly. As part of the fix, such a statement now causes an
     implicit commit before and after it is executed.  However, it does
     not cause a commit when used to create a temporary table.
     (Bug#22864 (http://bugs.mysql.com/22864))

   * `mysql_upgrade' failed when called with a `basedir' pathname
     containing spaces.  (Bug#22801 (http://bugs.mysql.com/22801))

   * Using `INSTALL PLUGIN' followed by a restart of the server caused
     an error due to memory not being properly initialized.  (Bug#22694
     (http://bugs.mysql.com/22694))

   * `SET lc_time_names = VALUE ' allowed only exact literal values,
     not expression values.  (Bug#22647 (http://bugs.mysql.com/22647))

   * Changes to the `lc_time_names' system variable were not replicated.
     (Bug#22645 (http://bugs.mysql.com/22645))

   * A partitioned table that used the `DATA DIRECTORY' option, where
     the data directory was the same as the directory in which the
     table definition file resided, became corrupted following `ALTER
     TABLE ENGINE=ARCHIVE'. This was actually due to an issue with the
     `ARCHIVE' storage engine, and not with partitioned tables in
     general.  (Bug#22634 (http://bugs.mysql.com/22634))

   * The `STDDEV()' function returned a positive value for data sets
     consisting of a single value.  (Bug#22555
     (http://bugs.mysql.com/22555))

   * `SHOW COLUMNS' reported some `NOT NULL' columns as `NULL'.
     (Bug#22377 (http://bugs.mysql.com/22377))

   * A server crash occurred when using `LOAD DATA' to load a table
     containing a `NOT NULL' spatial column, when the statement did not
     load the spatial column. Now a `NULL supplied to NOT NULL column'
     error occurs.  (Bug#22372 (http://bugs.mysql.com/22372))

   * An `ALTER TABLE' statement that used a `RENAME' clause in
     combination with a `MODIFY' or `CHANGE' that did not actually
     change the table (for example, when it changed a column's type
     from `INT' to `INT'). The behavior caused by this bug differed
     according to whether or not the storage engine used by the table
     was transactional or non-transactional. For transactional tables
     (such as those using the `InnoDB' storage engine), the statement
     simply failed; for non-transactional tables (such as those using
     the `MyISAM' storage engine), the `ALTER TABLE' statement
     succeeding renaming the table, but subsequent `SELECT' statements
     against the renamed table would fail.  (Bug#22369
     (http://bugs.mysql.com/22369))

   * The Instance Manager `STOP INSTANCE' command could not be applied
     to instances in the `Crashed', `Failed', or `Abandoned' state.
     (Bug#22306 (http://bugs.mysql.com/22306))

   * `DATE_ADD()' requires complete dates with no `zero' parts, but
     sometimes did not return `NULL' when given such a date.
     (Bug#22229 (http://bugs.mysql.com/22229))

   * Some small double precision numbers (such as `1.00000001e-300')
     that should have been accepted were truncated to zero.  (Bug#22129
     (http://bugs.mysql.com/22129))

   * Changing the value of `MI_KEY_BLOCK_LENGTH' in `myisam.h' and
     recompiling MySQL resulted in a `myisamchk' that saw existing
     `MyISAM' tables as corrupt.  (Bug#22119
     (http://bugs.mysql.com/22119))

   * For a nonexistent table, `DROP TEMPORARY TABLE' failed with an
     incorrect error message if `read_only' was enabled.  (Bug#22077
     (http://bugs.mysql.com/22077))

   * A crash of the MySQL Server could occur when unpacking a `BLOB'
     column from a row in a corrupted MyISAM table. This could happen
     when trying to repair a table using either `REPAIR TABLE' or
     `myisamchk'; it could also happen when trying to access such a
     `broken' row using statements like `SELECT' if the table was not
     marked as crashed.  (Bug#22053 (http://bugs.mysql.com/22053))

   * The code for generating `USE' statements for binary logging of
     `CREATE PROCEDURE' statements resulted in confusing output from
     `mysqlbinlog' for `DROP PROCEDURE' statements.  (Bug#22043
     (http://bugs.mysql.com/22043))

   * `STR_TO_DATE()' returned `NULL' if the format string contained a
     space following a non-format character.  (Bug#22029
     (http://bugs.mysql.com/22029))

   * It was possible to use `DATETIME' values whose year, month, and
     day parts were all zeroes but whose hour, minute, and second parts
     contained nonzero values, an example of such an illegal `DATETIME'
     being `'0000-00-00 11:23:45''.

     *Note*:

     This fix was reverted in MySQL 5.1.18.

     (Bug#21789 (http://bugs.mysql.com/21789)) See also Bug#25301
     (http://bugs.mysql.com/25301)

   * SSL connections could hang at connection shutdown.  (Bug#21781
     (http://bugs.mysql.com/21781), Bug#24148
     (http://bugs.mysql.com/24148))

   * yaSSL crashed on pre-Pentium Intel CPUs.  (Bug#21765
     (http://bugs.mysql.com/21765))

   * Using `FLUSH TABLES' in one connection while another connection is
     using `HANDLER' statements caused a server crash.

     *Note*:

     This fix was reverted in MySQL 5.1.22

     (Bug#21587 (http://bugs.mysql.com/21587)) See also Bug#29474
     (http://bugs.mysql.com/29474)

   * The `FEDERATED' storage engine did not support the `euckr'
     character set.  (Bug#21556 (http://bugs.mysql.com/21556))

   * `InnoDB' crashed while performing XA recovery of prepared
     transactions.  (Bug#21468 (http://bugs.mysql.com/21468))

   * It was possible to set the backslash character (` `\' ') as the
     delimiter character using `DELIMITER', but not actually possible
     to use it as the delimiter.  (Bug#21412
     (http://bugs.mysql.com/21412))

   * Using `ALTER TABLE' to convert a `CSV' table containing `NULL'
     values to `MyISAM' resulted in warnings.  (Bug#21328
     (http://bugs.mysql.com/21328))

   * When updating a table that used a `JOIN' of the table itself (for
     example, when building trees) and the table was modified on one
     side of the expression, the table would either be reported as
     crashed or the wrong rows in the table would be updated.
     (Bug#21310 (http://bugs.mysql.com/21310))

   * `mysqld_error.h' was not installed when only the client libraries
     were built.  (Bug#21265 (http://bugs.mysql.com/21265))

   * `InnoDB': During a restart of the MySQL Server that followed the
     creation of a temporary table using the `InnoDB' storage engine,
     MySQL failed to clean up in such a way that `InnoDB' still
     attempted to find the files associated with such tables.
     (Bug#20867 (http://bugs.mysql.com/20867))

   * Selecting into variables sometimes returned incorrect wrong
     results.  (Bug#20836 (http://bugs.mysql.com/20836))

   * Queries of the form `SELECT ... WHERE STRING = ANY(...)' failed
     when the server used a single-byte character set and the client
     used a multi-byte character set.  (Bug#20835
     (http://bugs.mysql.com/20835))

   * `mysql_fix_privilege_tables.sql' altered the
     `table_privs.table_priv' column to contain too few privileges,
     causing loss of the `CREATE VIEW' and `SHOW VIEW' privileges.
     (Bug#20589 (http://bugs.mysql.com/20589))

   * A stored routine containing semicolon in its body could not be
     reloaded from a dump of a binary log.  (Bug#20396
     (http://bugs.mysql.com/20396))

   * `SELECT ... FOR UPDATE', `SELECT ...  LOCK IN SHARE MODE',
     `DELETE', and `UPDATE' statements executed using a full table scan
     were not releasing locks on rows that did not satisfy the `WHERE'
     condition.  (Bug#20390 (http://bugs.mysql.com/20390))

   * The `BUILD/check-cpu' script did not recognize Celeron processors.
     (Bug#20061 (http://bugs.mysql.com/20061))

   * Unsigned `BIGINT' values treated as signed values by the `MOD()'
     function.  (Bug#19955 (http://bugs.mysql.com/19955))

   * Compiling PHP 5.1 with the MySQL static libraries failed on some
     versions of Linux.  (Bug#19817 (http://bugs.mysql.com/19817))

   * The `DELIMITER' statement did not work correctly when used in an
     SQL file run using the `SOURCE' statement.  (Bug#19799
     (http://bugs.mysql.com/19799))

   * For `SET', `SELECT', and `DO' statements that invoked a stored
     function from a database other than the default database, the
     function invocation could fail to be replicated.  (Bug#19725
     (http://bugs.mysql.com/19725))

   * `mysqltest' incorrectly tried to retrieve result sets for some
     queries where no result set was available.  (Bug#19410
     (http://bugs.mysql.com/19410))

   * `VARBINARY' column values inserted on a MySQL 4.1 server had
     trailing zeroes following upgrade to MySQL 5.0 or later.
     (Bug#19371 (http://bugs.mysql.com/19371))

   * Some `CASE' statements inside stored routines could lead to
     excessive resource usage or a crash of the server.  (Bug#19194
     (http://bugs.mysql.com/19194), Bug#24854
     (http://bugs.mysql.com/24854))

   * Instance Manager could crash during shutdown.  (Bug#19044
     (http://bugs.mysql.com/19044))

   * `myisampack' wrote to unallocated memory, causing a crash.
     (Bug#17951 (http://bugs.mysql.com/17951))

   * `FLUSH LOGS' or `mysqladmin flush-logs' caused a server crash if
     the binary log was not open.  (Bug#17733
     (http://bugs.mysql.com/17733))

   * `mysql_fix_privilege_tables' did not accept a password containing
     embedded space or apostrophe characters.  (Bug#17700
     (http://bugs.mysql.com/17700))

   * No warning was issued for use of the `DATA DIRECTORY' or `INDEX
     DIRECTORY' table options on a platform that does not support them.
     (Bug#17498 (http://bugs.mysql.com/17498))

   * The `FEDERATED' storage engine did not support the `utf8'
     character set.  (Bug#17044 (http://bugs.mysql.com/17044))

   * The optimizer removes expressions from `GROUP BY' and `DISTINCT'
     clauses if they happen to participate in ` EXPRESSION = CONSTANT'
     predicates of the `WHERE' clause, the idea being that, if the
     expression is equal to a constant, then it cannot take on multiple
     values. However, for predicates where the expression and the
     constant item are of different result types (for example, when a
     string column is compared to 0), this is not valid, and can lead
     to invalid results in such cases. The optimizer now performs an
     additional check of the result types of the expression and the
     constant; if their types differ, then the expression is not
     removed from the `GROUP BY' list.  (Bug#15881
     (http://bugs.mysql.com/15881))

   * When a prepared statement failed during the prepare operation, the
     error code was not cleared when it was reused, even if the
     subsequent use was successful.  (Bug#15518
     (http://bugs.mysql.com/15518))

   * Dropping a user-defined function sometimes did not remove the UDF
     entry from the `mysql.proc' table.  (Bug#15439
     (http://bugs.mysql.com/15439))

   * Inserting a row into a table without specifying a value for a
     `BINARY(N) NOT NULL' column caused the column to be set to spaces,
     not zeroes.  (Bug#14171 (http://bugs.mysql.com/14171))

   * On Windows, the `SLEEP()' function could sleep too long,
     especially after a change to the system clock.  (Bug#14094
     (http://bugs.mysql.com/14094), Bug#24686
     (http://bugs.mysql.com/24686), Bug#17635
     (http://bugs.mysql.com/17635))

   * `mysqldump --order-by-primary' failed if the primary key name was
     an identifier that required quoting.  (Bug#13926
     (http://bugs.mysql.com/13926))

   * Subqueries of the form `NULL IN (SELECT ...)' returned invalid
     results.  (Bug#8804 (http://bugs.mysql.com/8804), Bug#23485
     (http://bugs.mysql.com/23485))


File: manual.info,  Node: news-5-1-14,  Next: news-5-1-13,  Prev: news-5-1-15,  Up: news-5-1-x

C.1.16 Changes in MySQL 5.1.14 (05 December 2006)
-------------------------------------------------

This is a new Beta development release, fixing recently discovered bugs.

*Note*:

This Beta release, as any other pre-production release, should not be
installed on _production_ level systems or systems with critical data.
It is good practice to back up your data before installing any new
version of software.  Although MySQL has worked very hard to ensure a
high level of quality, protect your data by making a backup as you
would for any software beta release. Please refer to our bug database at
`http://bugs.mysql.com/' for more details about the individual bugs
fixed in this version.

This section documents all changes and bug fixes that have been applied
since the last official MySQL release. If you would like to receive
more fine-grained and personalized _update alerts_ about fixes that are
relevant to the version and features you use, please consider
subscribing to _MySQL Enterprise_ (a commercial MySQL offering). For
more details please see `http://www.mysql.com/products/enterprise'.

Functionality added or changed:

   * *Cluster Replication*: *Incompatible Change*: Two major changes
     have taken place with regard to the MySQL Cluster system tables.
     These are:

       1. The `cluster' database is no longer used.  The tables
          formerly found in the `cluster' database are now in the
          `mysql' database, and have been renamed as `ndb_binlog_index',
          `ndb_apply_status', and `ndb_schema'.

       2. The `mysql.ndb_apply_status' and `mysql.ndb_schema' tables
          (formerly `cluster.apply_status' and `cluster.schema' are now
          created by `ndb_restore', in the event that they do not
          already exist on the slave cluster.

     *Note*:

     When upgrading from versions of MySQL previous to 5.1.14 to 5.1.14
     or later, `mysql_fix_privilege_tables' merely creates a new
     `mysql.ndb_binlog_index' table, but does not remove the existing
     `cluster' database (or, if upgrading from MySQL 5.1.7 or earlier,
     the existing `cluster_replication' database), nor any of the
     tables in it.

     For more information, see *Note mysql-cluster-replication-schema::.
     (Bug#14612 (http://bugs.mysql.com/14612))

   * *Cluster Replication*: *Incompatible Change*: The `cluster'
     database is no longer used. The tables formerly found in the
     `cluster' database are now in the `mysql' database, and have been
     renamed as `ndb_binlog_index', `ndb_apply_status', and
     `ndb_schema'.

   * *Incompatible Change*: The `prepared_stmt_count' system variable
     has been converted to the `Prepared_stmt_count' global status
     variable (viewable with the `SHOW GLOBAL STATUS' statement).
     (Bug#23159 (http://bugs.mysql.com/23159))

   * *Incompatible Change*: Previously, you could create a user-defined
     function (UDF) or stored function with the same name as a built-in
     function, but could not invoke the UDF. Now an error occurs if you
     try to create such a UDF. The server also now generates a warning
     if you create a stored function with the same name as a built-in
     function. It is not considered an error to create a stored
     function with the same name as a built-in function because you can
     invoke the function using ` DB_NAME.FUNC_NAME()' syntax. However,
     the server now generates a warning in this case.

     See *Note function-resolution::, for the rules describing how the
     server interprets references to different kinds of functions.
     (Bug#22619 (http://bugs.mysql.com/22619), Bug#18239
     (http://bugs.mysql.com/18239))

   * *MySQL Cluster*: Backup messages are now printed to the Cluster
     log.  (Bug#24544 (http://bugs.mysql.com/24544))

   * *MySQL Cluster*: Setting the configuration parameter
     `LockPagesInMainMemory' had no effect.  (Bug#24461
     (http://bugs.mysql.com/24461))

   * *MySQL Cluster*: The error message `Management server closed
     connection', when recorded in the MySQL error log, now includes a
     timestamp indicating when the error took place.  (Bug#21519
     (http://bugs.mysql.com/21519))

   * *MySQL Cluster*: It is now possible to create a unique hashed
     index on a column that is not defined as `NOT NULL'.

     *Note*:

     This change applies only to tables using the `NDB' storage engine.

     Unique indexes on columns in `NDB' tables do not store null values
     because they are mapped to primary keys in an internal index table
     (and primary keys cannot contain nulls).

     Normally, an additional ordered index is created when one creates
     unique indexes on `NDB' table columns; this can be used to search
     for `NULL' values.  However, if `USING HASH' is specified when such
     an index is created, no ordered index is created.

     The reason for permitting unique hash indexes with null values is
     that, in some cases, the user wants to save space if a large
     number of records are pre-allocated but not fully initialized.
     This also assumes that the user will _not_ try to search for null
     values. Since MySQL does not support indexes that are not allowed
     to be searched in some cases, the `NDB' storage engine uses a full
     table scan with pushed conditions for the referenced index columns
     to return the correct result.

     A warning is returned if one creates a unique nullable hash index,
     since the query optimizer should be provided a hint not to use it
     with `NULL' values if this can be avoided.  (Bug#21507
     (http://bugs.mysql.com/21507))

   * *MySQL Cluster*: (Disk Data): The output of `mysqldump' now
     includes by default all tablespace and logfile group definitions
     used by any tables or databases that are dumped.

     *Note*:

     The working of the `--all-tablespaces' or `-Y' option for
     `mysqldump' remains unaffected by this change.

     (Bug#20839 (http://bugs.mysql.com/20839))

   * `DROP TRIGGER' now supports an `IF EXISTS' clause.  (Bug#23703
     (http://bugs.mysql.com/23703))

   * Direct and indirect usage of stored routines, user-defined
     functions, and table references is now prohibited in `CREATE
     EVENT' and `ALTER EVENT' statements.

     See *Note create-event::, and *Note alter-event::, for more
     specific information.  (Bug#22830 (http://bugs.mysql.com/22830))

   * The XPath operators `<' and `>', as implemented in the
     `ExtractValue()' function, operated in reverse.

     With this fix, all standard XPath comparison operators should now
     be supported correctly for use with the `ExtractValue()' and
     `UpdateXML()' functions.  (Bug#22823 (http://bugs.mysql.com/22823))

   * For the `mysql' client, display of result set metadata now is
     enabled with the `--column-type-info' option rather than with
     `--debug-info'/`-T'.

   * `mysqladmin', `mysqlcheck', `mysqldump', `mysqlimport', and
     `mysqlshow' now accept the `--debug-info' option, which displays
     debugging information and memory and CPU usage statistics at
     program exit.

Bugs fixed:

   * *MySQL Cluster*: The failure of a data node failure during a
     schema operation could lead to additional node failures.
     (Bug#24752 (http://bugs.mysql.com/24752))

   * *MySQL Cluster*: A committed read could be attempted before a data
     node had time to connect, causing a timeout error.  (Bug#24717
     (http://bugs.mysql.com/24717))

   * *MySQL Cluster*: The simultaneous shutdown of `mysqld' and `ndbd'
     processes caused unnecessary locking.  (Bug#24655
     (http://bugs.mysql.com/24655))

   * *MySQL Cluster*: The failure of the master node in a node group
     during the allocation of node IDs could cause `ndb_mgmd' to hang.
     (Bug#24543 (http://bugs.mysql.com/24543))

   * *MySQL Cluster*: In certain rare cases, a data node could crash
     due to a typographical error in the MySQL Cluster source code.
     (Bug#24476 (http://bugs.mysql.com/24476))

   * *MySQL Cluster*: Creating a new tables containing a `BLOB' column
     when the server was short of memory could cause the server to
     crash.  (Bug#24470 (http://bugs.mysql.com/24470))

   * *MySQL Cluster*: Sudden disconnection of an SQL or data node could
     lead to shutdown of data nodes with the error `failed ndbrequire'.
     (Bug#24447 (http://bugs.mysql.com/24447))

   * *MySQL Cluster*: Any statement following the execution of `CREATE
     TABLE ... LIKE NDB_TABLE' (where NDB_TABLE was a table using the
     `NDB' storage engine), would cause the `mysql' client to hang.
     (Bug#24301 (http://bugs.mysql.com/24301))

   * *MySQL Cluster*: (Disk Data): Excessive fragmentation of Disk Data
     files (including log files and data files) could occur during the
     course of normal use.  (Bug#24143 (http://bugs.mysql.com/24143))

   * *MySQL Cluster*: When the management client command `ALL RESTART
     -i' was executed while one data node was not running, all data
     nodes in the cluster were shut down.  (Bug#24105
     (http://bugs.mysql.com/24105))

   * *MySQL Cluster*: A query using an index scan followed by a delete
     operation, and then a rollback could cause one or more data nodes
     to crash.  (Bug#24039 (http://bugs.mysql.com/24039))

   * *MySQL Cluster*: (Disk Data): Under some circumstances, a `DELETE'
     from a Disk Data table could cause `mysqld' to crash.  (Bug#23542
     (http://bugs.mysql.com/23542))

   * *MySQL Cluster*: It was possible for the sum of the
     `MaxNoOfTables', `MaxNoOfOrderedIndexes', and
     `MaxNoOfUniqueHashIndexes' configuration parameters, plus the
     number of system tables to exceed the maximum value for a `Uint32'
     number. In such a case, the cluster's data nodes failed to start,
     and no reason for this could easily be determined from the error
     messages provided.  (Bug#22548 (http://bugs.mysql.com/22548))

   * *MySQL Cluster*: A value equal to or greater than the allowed
     maximum for `LongMessageBuffer' caused all data nodes to crash.
     (Bug#22547 (http://bugs.mysql.com/22547))

   * *MySQL Cluster*: Multiple occurrences of error conditions were
     logged with duplicat error messages rather than being reported
     with a single error message stating that the error was encountered
     N times.  (Bug#22313 (http://bugs.mysql.com/22313))

   * *MySQL Cluster*: Given a table `mytbl' in a database `mydb' on a
     MySQL Server acting as an SQL node in a MySQL Cluster, then,
     following multiple `ALTER TABLE mytbl ENGINE=ENGINE' statements --
     first, to change the storage engine used for a table to `NDB', and
     then again to change the table to use a non-`NDB' storage engine --
     a `DROP DATABASE mydb' statement executed on any SQL node in the
     cluster would cause `mydb' to be dropped on _all_ SQL nodes in the
     cluster, even if `mydb' contained non-`NDB' tables.  (Bug#21495
     (http://bugs.mysql.com/21495))

   * *MySQL Cluster*: An incorrect error message was displayed in the
     event that the value of the `MaxNoOfOrderedIndexes' parameter was
     set too low.  (Bug#20065 (http://bugs.mysql.com/20065))

   * *MySQL Cluster*: An incorrect error message was displayed in the
     event that the value of the `DataMemory' parameter was
     insufficient for the amount of data to be stored by the cluster.
     (Bug#19808 (http://bugs.mysql.com/19808))

   * *MySQL Cluster*: Some values of `MaxNoOfTriggers' could cause the
     server to become inaccessible following startup of the data nodes.
     (Bug#19454 (http://bugs.mysql.com/19454))

   * *MySQL Cluster*: If the value set for `MaxNoOfAttributes' is
     excessive, a suitable error message is now returned.  (Bug#19352
     (http://bugs.mysql.com/19352))

   * *MySQL Cluster*: Different error messages were returned for
     similar cases involving failure to allocate memory for Cluster
     operations.  (Bug#19203 (http://bugs.mysql.com/19203))

   * *MySQL Cluster*: A unique constraint violation was not ignored by
     an `UPDATE IGNORE' statement when the constraint violation
     occurred on a non-primary key.  (Bug#18487
     (http://bugs.mysql.com/18487), Bug#24303
     (http://bugs.mysql.com/24303))

   * *MySQL Cluster*: (Replication): If errors occurred during purging
     of the binary logs, extraneous rows could remain left in the
     `binlog_index' table.  (Bug#15021 (http://bugs.mysql.com/15021))

   * *Disk Data*: `ndb_restore' sometimes failed when attempting to
     restore Disk Data tables due to data node failure caused by
     accessing uninitialized memory.  (Bug#24331
     (http://bugs.mysql.com/24331))

   * *Disk Data*: It was possible to execute a statement for creating a
     Disk Data table that referred to a nonexistent tablespace, in
     which case the table created was actually an in-memory `NDB'
     table. Such a statement now fails instead, with an appropriate
     error message.  (Bug#23576 (http://bugs.mysql.com/23576))

   * *Cluster API*: Using `BIT' values with any of the comparison
     methods of the `NdbScanFilter' class caused data nodes to fail.
     (Bug#24503 (http://bugs.mysql.com/24503))

   * *Cluster API*: Some MGM API function calls could yield incorrect
     return values in certain cases where the cluster was operating
     under a very high load, or experienced timeouts in inter-node
     communications.  (Bug#24011 (http://bugs.mysql.com/24011))

   * In some cases, a function that should be parsed as a user-defined
     function was parsed as a stored function.  (Bug#24736
     (http://bugs.mysql.com/24736))

   * Some unnecessary Valgrind warnings were removed from the server.  .
     (Bug#24488 (http://bugs.mysql.com/24488), Bug#24533
     (http://bugs.mysql.com/24533))

   * The server source code had multiple exportable definitions of the
     `field_in_record_is_null()' function. These are now all declared
     `static'.  (Bug#24190 (http://bugs.mysql.com/24190))

   * The loose index scan optimization for `GROUP BY' with `MIN' or
     `MAX' was not applied within other queries, such as `CREATE TABLE
     ... SELECT ...', `INSERT ... SELECT ...', or in the `FROM' clauses
     of subqueries.  (Bug#24156 (http://bugs.mysql.com/24156))

   * Subqueries for which a pushed-down condition did not produce
     exactly one key field could cause a server crash.  (Bug#24056
     (http://bugs.mysql.com/24056))

   * The size of `MEMORY' tables and internal temporary tables was
     limited to 4GB on 64-bit Windows systems.  (Bug#24052
     (http://bugs.mysql.com/24052))

   * With row-based binary logging, replicated multiple-statement
     transaction deadlocks did not return the correct error code,
     causing the slave SQL thread to stop rather than roll back and
     re-execute.  (Bug#23831 (http://bugs.mysql.com/23831))

   * `LAST_DAY('0000-00-00')' could cause a server crash.  (Bug#23653
     (http://bugs.mysql.com/23653))

   * A trigger that invoked a stored function could cause a server
     crash when activated by different client connections.  (Bug#23651
     (http://bugs.mysql.com/23651))

   * The stack size for NetWare binaries was increased to 128KB to
     prevent problems caused by insufficient stack size.  (Bug#23504
     (http://bugs.mysql.com/23504))

   * If elements in a non-top-level `IN' subquery were accessed by an
     index and the subquery result set included a `NULL' value, the
     quantified predicate that contained the subquery was evaluated to
     `NULL' when it should return a non-`NULL' value.  (Bug#23478
     (http://bugs.mysql.com/23478))

   * When applying the `group_concat_max_len' limit, `GROUP_CONCAT()'
     could truncate multi-byte characters in the middle.  (Bug#23451
     (http://bugs.mysql.com/23451))

   * *Note `mysql_affected_rows()': mysql-affected-rows. could return
     values different from *Note `mysql_stmt_affected_rows()':
     mysql-stmt-affected-rows.  for the same sequence of statements.
     (Bug#23383 (http://bugs.mysql.com/23383))

   * Calculation of `COUNT(DISTINCT)', `AVG(DISTINCT)', or
     `SUM(DISTINCT)' when they are referenced more than once in a
     single query with `GROUP BY' could cause a server crash.
     (Bug#23184 (http://bugs.mysql.com/23184))

   * Changes to character set variables prior to an action on a
     replication-ignored table were forgotten by slave servers.
     (Bug#22877 (http://bugs.mysql.com/22877))

   * With row-based binary logging, for `CREATE TABLE IF NOT EXISTS
     LIKE TEMPORARY_TABLE ' statements, the `IF NOT EXISTS' clause was
     not logged.  (Bug#22762 (http://bugs.mysql.com/22762))

   * `BENCHMARK()', `ENCODE()', `DECODE()', and `FORMAT()' could only
     accept a constant for some parameters, and could not be used in
     prepared statements.  (Bug#22684 (http://bugs.mysql.com/22684))

   * Queries using a column alias in an expression as part of an `ORDER
     BY' clause failed, an example of such a query being `SELECT mycol
     + 1 AS mynum FROM mytable ORDER BY 30 - mynum'.  (Bug#22457
     (http://bugs.mysql.com/22457))

   * Using `EXPLAIN' caused a server crash for queries that selected
     from `INFORMATION_SCHEMA' in a subquery in the `FROM' clause.
     (Bug#22413 (http://bugs.mysql.com/22413))

   * Instance Manager option-parsing code caused memory-allocation
     errors.  (Bug#22242 (http://bugs.mysql.com/22242))

   * Trailing spaces were not removed from Unicode `CHAR' column values
     when used in indexes. This resulted in excessive usage of storage
     space, and could affect the results of some `ORDER BY' queries that
     made use of such indexes.

     *Note*:

     When upgrading, it is necessary to re-create any existing indexes
     on Unicode `CHAR' columns in order to take advantage of the fix.
     This can be done by using a `REPAIR TABLE' statement on each
     affected table.

     (Bug#22052 (http://bugs.mysql.com/22052))

   * With row-based binary logging, `CREATE TABLE IF NOT EXISTS SELECT'
     statements were not logged properly.  (Bug#22027
     (http://bugs.mysql.com/22027))

   * In some cases, the parser failed to distinguish a user-defined
     function from a stored function.  (Bug#21809
     (http://bugs.mysql.com/21809))

   * Inserting a default or invalid value into a spatial column could
     fail with `Unknown error' rather than a more appropriate error.
     (Bug#21790 (http://bugs.mysql.com/21790))

   * Evaluation of subqueries that require the filesort algorithm were
     allocating and freeing the `sort_buffer_size' buffer many times,
     resulting in slow performance. Now the buffer is allocated once and
     reused.  (Bug#21727 (http://bugs.mysql.com/21727))

   * Through the C API, the member strings in `MYSQL_FIELD' for a query
     that contains expressions may return incorrect results.
     (Bug#21635 (http://bugs.mysql.com/21635))

   * View columns were always handled as having implicit derivation,
     leading to `illegal mix of collation errors' for some views in
     `UNION' operations. Now view column derivation comes from the
     original expression given in the view definition.  (Bug#21505
     (http://bugs.mysql.com/21505))

   * `INET_ATON()' returned a signed `BIGINT' value, not an unsigned
     value.  (Bug#21466 (http://bugs.mysql.com/21466))

   * For debug builds, `mysqladmin shutdown' displayed an extraneous
     `skipped 9 bytes from file: socket (3)' message.  (Bug#21428
     (http://bugs.mysql.com/21428))

   * For renaming of views, encoding of table name to filenames was not
     performed.  (Bug#21370 (http://bugs.mysql.com/21370))

   * `CREATE FUNCTION X()' and `CREATE FUNCTION Y()' failed with a
     syntax error instead of warning the user that these function names
     are already used (for GIS functions).  (Bug#21025
     (http://bugs.mysql.com/21025))

   * On slave servers, transactions that exceeded the lock wait timeout
     failed to roll back properly.  (Bug#20697
     (http://bugs.mysql.com/20697))

   * `CONCURRENT' did not work correctly for `LOAD DATA INFILE'.
     (Bug#20637 (http://bugs.mysql.com/20637))

   * With `lower_case_table_names' set to 1, `SHOW CREATE TABLE'
     printed incorrect output for table names containing Turkish I
     (LATIN CAPITAL LETTER I WITH DOT ABOVE).  (Bug#20404
     (http://bugs.mysql.com/20404))

   * A query with a subquery that references columns of a view from the
     outer `SELECT' could return an incorrect result if used from a
     prepared statement.  (Bug#20327 (http://bugs.mysql.com/20327))

   * For queries that select from a view, the server was returning
     `MYSQL_FIELD' metadata inconsistently for view names and table
     names. For view columns, the server now returns the view name in
     the `table' field and, if the column selects from an underlying
     table, the table name in the `org_table' field.  (Bug#20191
     (http://bugs.mysql.com/20191))

   * Invalidating the query cache caused a server crash for `INSERT
     INTO ... SELECT' statements that selected from a view.  (Bug#20045
     (http://bugs.mysql.com/20045))

   * For a cast of a `DATETIME' value containing microseconds to
     `DECIMAL', the microseconds part was truncated without generating
     a warning. Now the microseconds part is preserved.  (Bug#19491
     (http://bugs.mysql.com/19491))

   * SQL statements close to the size of `max_allowed_packet' could
     produce binary log events larger than `max_allowed_packet' that
     could not be read by slave servers.  (Bug#19402
     (http://bugs.mysql.com/19402))

   * The server could send incorrect column count information to the
     client for queries that produce a larger number of columns than
     can fit in a two-byte number.  (Bug#19216
     (http://bugs.mysql.com/19216))

   * For some problems relating to character set conversion or
     incorrect string values for `INSERT' or `UPDATE', the server was
     reporting truncation or length errors instead.  (Bug#18908
     (http://bugs.mysql.com/18908))

   * Constant expressions and some numeric constants used as input
     parameters to user-defined functions were not treated as constants.
     (Bug#18761 (http://bugs.mysql.com/18761))

   * Attempting to use a view containing `DEFINER' information for a
     non-existent user resulted in an error message that revealed the
     definer account. Now the definer is revealed only to superusers.
     Other users receive only an `access denied' message.  (Bug#17254
     (http://bugs.mysql.com/17254))

   * `IN()' and `CHAR()' can return `NULL', but did not signal that to
     the query processor, causing incorrect results for `IS NULL'
     operations.  (Bug#17047 (http://bugs.mysql.com/17047))

   * Warnings were generated when explicitly casting a character to a
     number (for example, `CAST('x' AS SIGNED)'), but not for implicit
     conversions in simple arithmetic operations (such as `'x' + 0').
     Now warnings are generated in all cases.  (Bug#11927
     (http://bugs.mysql.com/11927))

   * Metadata for columns calculated from scalar subqueries was limited
     to integer, double, or string, even if the actual type of the
     column was different.  (Bug#11032 (http://bugs.mysql.com/11032))


File: manual.info,  Node: news-5-1-13,  Next: news-5-1-12,  Prev: news-5-1-14,  Up: news-5-1-x

C.1.17 Changes in MySQL 5.1.13 (Not released)
---------------------------------------------

This is a new Beta development release, fixing recently discovered bugs.

*Note*:

This Beta release, as any other pre-production release, should not be
installed on _production_ level systems or systems with critical data.
It is good practice to back up your data before installing any new
version of software.  Although MySQL has worked very hard to ensure a
high level of quality, protect your data by making a backup as you
would for any software beta release. Please refer to our bug database at
`http://bugs.mysql.com/' for more details about the individual bugs
fixed in this version.

This section documents all changes and bug fixes that have been applied
since the last official MySQL release. If you would like to receive
more fine-grained and personalized _update alerts_ about fixes that are
relevant to the version and features you use, please consider
subscribing to _MySQL Enterprise_ (a commercial MySQL offering). For
more details please see `http://www.mysql.com/products/enterprise'.

Functionality added or changed:

   * *Incompatible Change*: The number of function names affected by
     `IGNORE_SPACE' was reduced significantly in MySQL 5.1.13, from
     about 200 to about 30. (For details about `IGNORE_SPACE', see
     *Note function-resolution::.) This change improves the consistency
     of parser operation. However, it also introduces the possibility
     of incompatibility for old SQL code that relies on the following
     conditions:

        * `IGNORE_SPACE' is disabled.

        * The presence or absence of whitespace following a function
          name is used to distinguish between a built-in function and
          stored function that have the same name (for example, `PI()'
          versus `PI ()').

     For functions that are no longer affected by `IGNORE_SPACE' as of
     MySQL 5.1.13, that strategy no longer works. Either of the
     following approaches can be used if you have code that is subject
     to the preceding incompatibility:

        * If a stored function has a name that conflicts with a
          built-in function, refer to the stored function with a schema
          name qualifier, regardless of whether whitespace is present.
          For example, write ` SCHEMA_NAME.PI()' or `SCHEMA_NAME.PI ()'.

        * Alternatively, rename the stored function to use a
          non-conflicting name and change invocations of the function
          to use the new name.

     (Bug#21114 (http://bugs.mysql.com/21114))

   * *Incompatible Change*: The `innodb_buffer_pool_awe_mem_mb' system
     variable has been removed and should no longer be used.

   * *MySQL Cluster*: A change in the interfaces for the
     `INFORMATION_SCHEMA.FILES' table has made the table accessible to
     storage engines other than `NDB'.  (Bug#23013
     (http://bugs.mysql.com/23013))

   * Binary distributions of MySQL 5.1.12 were built without support
     for partitioning. This has been corrected except for NetWare.
     (Bug#23949 (http://bugs.mysql.com/23949))

   * If the user specified the server options `--max-connections=N ' or
     `--table-open-cache=M ', a warning would be given in some cases
     that some values were recalculated, with the result that
     `--table-open-cache' could be assigned greater value.

     In such cases, both the warning and the increase in the
     `--table-open-cache' value were completely harmless. Note also
     that it is not possible for the MySQL Server to predict or to
     control limitations on the maximum number of open files, since
     this is determined by the operating system.

     The value of `--table-open-cache' is no longer increased
     automatically, and a warning is now given only if some values had
     to be decreased due to operating system limits.  (Bug#21915
     (http://bugs.mysql.com/21915))

   * For the `CALL' statement, stored procedures that take no arguments
     now can be invoked without parentheses.  That is, `CALL p()' and
     `CALL p' are equivalent.  (Bug#21462 (http://bugs.mysql.com/21462))

   * `mysql_upgrade' now passes all the parameters specified on the
     command line to both `mysqlcheck' and `mysql' using the
     `upgrade_defaults' file.  (Bug#20100 (http://bugs.mysql.com/20100))

   * `mysqldump --single-transaction' now uses `START TRANSACTION
     /*!40100 WITH CONSISTENT SNAPSHOT */' rather than `BEGIN' to start
     a transaction, so that a consistent snapshot will be used on those
     servers that support it.  (Bug#19660 (http://bugs.mysql.com/19660))

Bugs fixed:

   * *MySQL Cluster*: Backup of a cluster failed if there were any
     tables with 128 or more columns.  (Bug#23502
     (http://bugs.mysql.com/23502))

   * *MySQL Cluster*: Cluster backups failed when there were more than
     2048 schema objects in the cluster.  (Bug#23499
     (http://bugs.mysql.com/23499))

   * *MySQL Cluster*: Restoring a cluster failed if there were any
     tables with 128 or more columns.  (Bug#23494
     (http://bugs.mysql.com/23494))

   * *MySQL Cluster*: The management client command `ALL DUMP 1000'
     would cause the cluster to crash if data nodes were connected to
     the cluster but not yret fully started.  (Bug#23203
     (http://bugs.mysql.com/23203))

   * *MySQL Cluster*: `INSERT ... ON DUPLICATE KEY UPDATE' on an `NDB'
     table could lead to deadlocks and memory leaks.  (Bug#23200
     (http://bugs.mysql.com/23200))

   * *MySQL Cluster*: An `NDB' source file included a `memset()' call
     with reversed arguments.  (Bug#23169 (http://bugs.mysql.com/23169))

   * *MySQL Cluster*: If a node restart could not be performed from the
     REDO log, no node takeover took place. This could cause partitions
     to be left empty during a system restart.  (Bug#22893
     (http://bugs.mysql.com/22893))

   * *MySQL Cluster*: Multiple node restarts in rapid succession could
     cause a system restart to fail , or induce a race condition.
     (Bug#22892 (http://bugs.mysql.com/22892), Bug#23210
     (http://bugs.mysql.com/23210))

   * *MySQL Cluster*: Attempting to create a unique constraint with
     `USING HASH' on an `NDB' table caused `mysqld' to crash.
     (Bug#21873 (http://bugs.mysql.com/21873))

   * *MySQL Cluster*: When inserting a row into an `NDB' table with a
     duplicate value for a non-primary unique key, the error issued
     would reference the wrong key.  (Bug#21072
     (http://bugs.mysql.com/21072))

   * *MySQL Cluster*: Aborting a cluster backup too soon after starting
     it caused a forced shutdown of the data nodes.  (Bug#19148
     (http://bugs.mysql.com/19148))

   * *Disk Data*: In the event of an aborted multiple update, the space
     in the Disk Data log buffer to be freed as a result was actually
     freed twice, which could eventually lead to a crash.  (Bug#23430
     (http://bugs.mysql.com/23430))

   * *Cluster API*: When multiple processes or threads in parallel
     performed the same ordered scan with exclusive lock and updated
     the retrieved records, the scan could skip some records, which as
     a result were not updated.  (Bug#20446
     (http://bugs.mysql.com/20446))

   * There was a race condition in the `InnoDB'
     `fil_flush_file_spaces()' function.  (Bug#24098
     (http://bugs.mysql.com/24098))

   * yaSSL-related memory leaks were detected by Valgrind.  (Bug#23981
     (http://bugs.mysql.com/23981))

   * MySQL 5.0.26 introduced an ABI incompatibility, which this release
     reverts. Programs compiled against 5.0.26 are not compatible with
     any other version and must be recompiled.  (Bug#23427
     (http://bugs.mysql.com/23427))

   * `M % 0' returns `NULL', but (` M % 0) IS NULL' evaluated to false.
     (Bug#23411 (http://bugs.mysql.com/23411))

   * For not-yet-authenticated connections, the `Time' column in `SHOW
     PROCESSLIST' was a random value rather than `NULL'.  (Bug#23379
     (http://bugs.mysql.com/23379))

   * `InnoDB' crashed when trying to display an error message about a
     foreign key constraint violation when the two tables are in
     different schemas.  (Bug#23368 (http://bugs.mysql.com/23368))

   * MySQL failed to build on Linux/Alpha.  (Bug#23256
     (http://bugs.mysql.com/23256)) This regression was introduced by
     Bug#21250 (http://bugs.mysql.com/21250)

   * If `COMPRESS()' returned `NULL', subsequent invocations of
     `COMPRESS()' within a result set or within a trigger also returned
     `NULL'.  (Bug#23254 (http://bugs.mysql.com/23254))

   * Insufficient memory (`myisam_sort_buffer_size') could cause a
     server crash for several operations on `MyISAM' tables: repair
     table, create index by sort, repair by sort, parallel repair, bulk
     insert.  (Bug#23175 (http://bugs.mysql.com/23175))

   * The column default value in the output from `SHOW COLUMNS' or
     `SELECT FROM INFORMATION_SCHEMA.COLUMNS' was truncated to 64
     characters.  (Bug#23037 (http://bugs.mysql.com/23037))

   * `mysql' did not check for errors when fetching data during result
     set printing.  (Bug#22913 (http://bugs.mysql.com/22913))

   * The return value from `my_seek()' was ignored.  (Bug#22828
     (http://bugs.mysql.com/22828))

   * Use of `SQL_BIG_RESULT' did not influence the sort plan for query
     execution.  (Bug#22781 (http://bugs.mysql.com/22781))

   * The optimizer failed to use equality propagation for `BETWEEN' and
     `IN' predicates with string arguments.  (Bug#22753
     (http://bugs.mysql.com/22753))

   * The `Handler_rollback' status variable sometimes was incremented
     when no rollback had taken place.  (Bug#22728
     (http://bugs.mysql.com/22728))

   * The `Host' column in `SHOW PROCESSLIST' output was blank when the
     server was started with the `--skip-grant-tables' option.
     (Bug#22723 (http://bugs.mysql.com/22723))

   * If a table contains an `AUTO_INCREMENT' column, inserting into an
     insertable view on the table that does not include the
     `AUTO_INCREMENT' column should not change the value of
     `LAST_INSERT_ID()', because the side effects of inserting default
     values into columns not part of the view should not be visible.
     MySQL was incorrectly setting `LAST_INSERT_ID()' to zero.
     (Bug#22584 (http://bugs.mysql.com/22584))

   * The optimizer used the `ref' join type rather than `eq_ref' for a
     simple join on strings.  (Bug#22367 (http://bugs.mysql.com/22367))

   * Some queries that used `MAX()' and `GROUP BY' could incorrectly
     return an empty result.  (Bug#22342 (http://bugs.mysql.com/22342))

   * If an `init_connect' SQL statement produced an error, the
     connection was silently terminated with no error message. Now the
     server writes a warning to the error log.  (Bug#22158
     (http://bugs.mysql.com/22158))

   * An unhandled `NULL' pointer caused a server crash.  (Bug#22138
     (http://bugs.mysql.com/22138))

   * Incorrect warnings occurred for use of `CREATE TABLE ...  LIKE' or
     `REPAIR TABLE' with the log tables.  (Bug#21966
     (http://bugs.mysql.com/21966))

   * The optimizer sometimes mishandled R-tree indexes for `GEOMETRY'
     data types, resulting in a server crash.  (Bug#21888
     (http://bugs.mysql.com/21888))

   * Use of a DES-encrypted SSL certificate file caused a server crash.
     (Bug#21868 (http://bugs.mysql.com/21868))

   * Use of `PREPARE' with a `CREATE PROCEDURE' statement that
     contained a syntax error caused a server crash.  (Bug#21856
     (http://bugs.mysql.com/21856))

   * Adding a day, month, or year interval to a `DATE' value produced a
     `DATE', but adding a week interval produced a `DATETIME' value.
     Now all produce a `DATE' value.  (Bug#21811
     (http://bugs.mysql.com/21811))

   * Use of a subquery that invoked a function in the column list of
     the outer query resulted in a memory leak.  (Bug#21798
     (http://bugs.mysql.com/21798))

   * It was not possible to do an atomic rename of the log tables
     without the possibility of losing rows. Now you can do this:

          USE mysql;
          CREATE TABLE IF NOT EXISTS general_log2 LIKE general_log;
          RENAME TABLE general_log TO general_log_backup, general_log2 TO general_log;

     (Bug#21785 (http://bugs.mysql.com/21785), Bug#17544
     (http://bugs.mysql.com/17544))

   * Within a prepared statement, `SELECT (COUNT(*) = 1)' (or similar
     use of other aggregate functions) did not return the correct
     result for statement re-execution.  (Bug#21354
     (http://bugs.mysql.com/21354))

   * Within a stored routine, a view definition cannot refer to routine
     parameters or local variables. However, an error did not occur
     until the routine was called. Now it occurs during parsing of the
     routine creation statement.

     *Note*:

     A side effect of this fix is that if you have already created such
     routines, and error will occur if you execute `SHOW CREATE
     PROCEDURE' or `SHOW CREATE FUNCTION'. You should drop these
     routines because they are erroneous.

     (Bug#20953 (http://bugs.mysql.com/20953))

   * In `mysql', invoking `connect' or `\r' with very long DB_NAME or
     HOST_NAME parameters caused buffer overflow.  (Bug#20894
     (http://bugs.mysql.com/20894))

   * `WITH ROLLUP' could group unequal values.  (Bug#20825
     (http://bugs.mysql.com/20825))

   * Range searches on columns with an index prefix could miss records.
     (Bug#20732 (http://bugs.mysql.com/20732))

   * The server did not allocate sufficient memory for some queries for
     which a `DISTINCT' to `GROUP BY' conversion is possible and an
     `ORDER BY' clause is present, resulting in a server crash.
     (Bug#20503 (http://bugs.mysql.com/20503))

   * `LIKE' searches failed for indexed `utf8' character columns.
     (Bug#20471 (http://bugs.mysql.com/20471))

   * With `SQL_MODE=TRADITIONAL', MySQL incorrectly aborted on warnings
     within stored routines and triggers.  (Bug#20028
     (http://bugs.mysql.com/20028))

   * `mysqldump --xml' produced invalid XML for `BLOB' data.
     (Bug#19745 (http://bugs.mysql.com/19745))

   * Column names were not quoted properly for replicated views.
     (Bug#19736 (http://bugs.mysql.com/19736))

   * The range analysis optimizer did not take into account predicates
     for which an index could be used after reading `const' tables. In
     some cases this resulted in non-optimal execution plans.
     (Bug#19579 (http://bugs.mysql.com/19579))

   * `FLUSH INSTANCES' in Instance Manager triggered an assertion
     failure.  (Bug#19368 (http://bugs.mysql.com/19368))

   * For a debug server, a reference to an undefined user variable in a
     prepared statment executed with `EXECUTE' caused an assertion
     failure.  (Bug#19356 (http://bugs.mysql.com/19356))

   * Within a trigger for a base table, selecting from a view on that
     base table failed.  (Bug#19111 (http://bugs.mysql.com/19111))

   * The value of the `warning_count' system variable was not being
     calculated correctly (also affecting `SHOW COUNT(*) WARNINGS').
     (Bug#19024 (http://bugs.mysql.com/19024))

   * `DELETE IGNORE' could hang for foreign key parent deletes.
     (Bug#18819 (http://bugs.mysql.com/18819))

   * `InnoDB' used table locks (not row locks) within stored functions.
     (Bug#18077 (http://bugs.mysql.com/18077))

   * `mysql' would lose its connection to the server if its standard
     output was not writable.  (Bug#17583 (http://bugs.mysql.com/17583))

   * At shutdown, Instance Manager told guarded server instances to
     stop, but did not wait until they actually stopped.  (Bug#17486
     (http://bugs.mysql.com/17486))

   * `mysql-test-run' did not work correctly for RPM-based
     installations.  (Bug#17194 (http://bugs.mysql.com/17194))

   * A client library crash was caused by executing a statement such as
     `SELECT * FROM t1 PROCEDURE ANALYSE()' using a server side cursor
     on a table `t1' that does not have the same number of columns as
     the output from `PROCEDURE ANALYSE()'.  (Bug#17039
     (http://bugs.mysql.com/17039))

   * The `WITH CHECK OPTION' for a view failed to prevent storing
     invalid column values for `UPDATE' statements.  (Bug#16813
     (http://bugs.mysql.com/16813))

   * `InnoDB' showed substandard performance with multiple queries
     running concurrently.  (Bug#15815 (http://bugs.mysql.com/15815))

   * `ALTER TABLE' was not able to rename a view.  (Bug#14959
     (http://bugs.mysql.com/14959))

   * Statements such as `DROP PROCEDURE' and `DROP VIEW' were written
     to the binary log too late due to a race condition.  (Bug#14262
     (http://bugs.mysql.com/14262))

   * A literal string in a `GROUP BY' clause could be interpreted as a
     column name.  (Bug#14019 (http://bugs.mysql.com/14019))

   * Entries in the slow query log could have an incorrect
     `Rows_examined' value.  (Bug#12240 (http://bugs.mysql.com/12240))

   * Lack of validation for input and output `TIME' values resulted in
     several problems: `SEC_TO_TIME()' in some cases did not clip large
     values to the `TIME' range appropriately; `SEC_TO_TIME()' treated
     `BIGINT UNSIGNED' values as signed; only truncation warnings were
     produced when both truncation and out-of-range `TIME' values
     occurred.  (Bug#11655 (http://bugs.mysql.com/11655), Bug#20927
     (http://bugs.mysql.com/20927))

   * Several string functions could return incorrect results when given
     very large length arguments.  (Bug#10963
     (http://bugs.mysql.com/10963))

   * `FROM_UNIXTIME()' did not accept arguments up to `POWER(2,31)-1',
     which it had previously.  (Bug#9191 (http://bugs.mysql.com/9191))

   * `OPTIMIZE TABLE' with `myisam_repair_threads' > 1 could result in
     `MyISAM' table corruption.  (Bug#8283 (http://bugs.mysql.com/8283))

   * Transient errors in replication from master to slave may trigger
     multiple `Got fatal error 1236: 'binlog truncated in the middle of
     event'' errors on the slave.  (Bug#4053
     (http://bugs.mysql.com/4053))


File: manual.info,  Node: news-5-1-12,  Next: news-5-1-11,  Prev: news-5-1-13,  Up: news-5-1-x

C.1.18 Changes in MySQL 5.1.12 (24 October 2006)
------------------------------------------------

This is a new Beta development release, fixing recently discovered bugs.

This section documents all changes and bug fixes that have been applied
since the last official MySQL release. If you would like to receive
more fine-grained and personalized _update alerts_ about fixes that are
relevant to the version and features you use, please consider
subscribing to _MySQL Enterprise_ (a commercial MySQL offering). For
more details please see `http://www.mysql.com/products/enterprise'.

Functionality added or changed:

   * *Incompatible Change*: *MySQL Cluster*: MySQL Cluster node and
     system restarts formerly required that all fragments use the same
     local checkpoint (LCP); beginning with this version, it is now
     possible for different fragments to use different LCPs during
     restarts. This means that data node filesystems must be rebuilt as
     part of any upgrade to this version by restarting all data nodes
     with the `--initial' option.

     See *Note mysql-cluster-upgrade-downgrade-compatibility::, and
     related sections of the Manual before upgrading a MySQL Cluster to
     version 5.1.12 or later.  (Bug#21478
     (http://bugs.mysql.com/21478), Bug#21271
     (http://bugs.mysql.com/21271))

   * *Incompatible Change*: In the `INFORMATION_SCHEMA.EVENTS' table,
     the `EVENT_DEFINITION' column now contains the SQL executed by a
     scheduled event.

     The `EVENT_BODY' column now contains the language used for the
     statement or statements shown in `EVENT_DEFINITION'. In MySQL 5.1,
     the value shown in `EVENT_BODY' is always `SQL'.

     These changes were made to bring this table into line with the
     `INFORMATION_SCHEMA.ROUTINES' table, and that table's
     `ROUTINE_BODY' and `ROUTINE_DEFINITION' columns.  (Bug#16992
     (http://bugs.mysql.com/16992))

   * *Incompatible Change*: Support for the BerkeleyDB (`BDB') engine
     has been dropped from this release. Any existing tables that are in
     BDB format will not be readable from within MySQL from 5.1.12 or
     newer. You should convert your tables to another storage engine
     _before_ upgrading to 5.1.12.

     Because of this change, the `SHOW [BDB] LOGS' statement has been
     dropped.

   * *Incompatible Change*: A number of MySQL constructs are now
     prohibited in partitioning expressions, beginning with this
     release. These include the following:

        * A number of MySQL functions. For a complete list of these,
          see *Note partitioning-limitations-functions::.

        * The bit operators `|', `&', `^', `<<', `>>', and `~'.

        * Nested function calls.

        * Calls to stored routines, UDFs, or plugins.

        * Character-to-integer conversions involving non-8-bit
          character sets or any of the `latin1_german2_ci',
          `latin2_czech_cs', or `cp1250_czech_cs' collations.

     These restrictions were added in part as a result of Bug#18198
     (http://bugs.mysql.com/18198) and related bug reports.

     For more information about these and other restrictions on
     partitioned tables in MySQL, see *Note partitioning-limitations::.

   * *Incompatible Change*: The permitted values for and behaviour of
     the `event_scheduler' system variable have changed.  Permitted
     values are now `ON', `OFF', and `DISABLED', with `OFF' being the
     default. It is not possible to change its value to or from
     `DISABLED' while the server is running.

     For details, see *Note events-overview::.

   * *Incompatible Change*: The plugin interface has changed: The
     `st_mysql_plugin' structure has a new `license' member to indicate
     the license type.  (The allowable values are defined in
     `mysql/plugin.h'.) This change is not backward compatible, so the
     API version (`MYSQL_PLUGIN_INTERFACE_VERSION') has changed.  For
     additional information, see *Note plugin-writing::.

   * *Incompatible Change*: The full-text parser plugin interface has
     changed in two ways:

        * The `MYSQL_FTPARSER_PARAM' structure has a new `flags'
          member. This is zero if there are no special flags, or
          `MYSQL_FTFLAGS_NEED_COPY', which means that
          `mysql_add_word()' must save a copy of the word (that is, it
          cannot use a pointer to the word because the word is in a
          buffer that will be overwritten.)

          This flag might be set or reset by MySQL before calling the
          parser plugin, by the parser plugin itself, or by the
          `mysql_parse()' function.

        * The `mysql_parse()' and `mysql_add_word()' functions now take
          a `MYSQL_FTPARSER_PARAM' as their first argument, not a
          `MYSQL_FTPARSER_PARAM::mysql_ftparam' as before.

     These changes are not backward compatible, so the API version
     (`MYSQL_FTPARSER_INTERFACE_VERSION') has changed. For additional
     information, see *Note plugin-writing::.

   * *Incompatible Change*: Storage engines can be pluggable at
     runtime, so the distinction between disabled and invalid storage
     engines no longer applies.  This affects the
     `NO_ENGINE_SUBSTITUTION' SQL mode, as described in *Note
     server-sql-mode::.

   * *Incompatible Change*: The namespace for scheduled events has
     changed, such that events are no longer unique to individual
     users. This also means that a user with the `EVENT' privilege on a
     given database can now view, alter, or drop any events defined on
     that database.

     If you used scheduled events in an earlier MySQL 5.1 release, you
     should rename any of them having the same name and defined on the
     same database but belonging to different users -- so that all
     events in a given database have unique names -- _before_ upgrading
     to 5.1.12 (or newer).

     For additional information, see *Note events-privileges::.

   * *Important Change*: *Partitioning*: *MySQL Cluster*: It is no
     longer possible to create Cluster tables using any partitioning
     type other than [`LINEAR'] `KEY'. Attempting to do so now raises
     an error.

   * *Important Change*: *MySQL Cluster*: `LOAD DATA INFILE' no longer
     causes an implicit commit for all storage engines. It now causes
     an implicit commit only for tables using the `NDB' storage engine.
     (Bug#11151 (http://bugs.mysql.com/11151))

   * *Important Change*: *MySQL Cluster*: The status variables
     `Ndb_connected_host' and `Ndb_connected_port' were renamed to
     `Ndb_config_from_host' and `Ndb_config_from_port', respectively.

   * *Important Change*: *Replication*: The default value for the
     `--binlog-format' server option is now `MIXED'.

   * *MySQL Cluster*: The `ndb_config' utility now accepts `-c' as a
     short form of the `--ndb-connectstring' option.  (Bug#22295
     (http://bugs.mysql.com/22295))

   * *MySQL Cluster*: Added the -bind-address option for `ndbd'.  This
     allows a data node process to be bound to a specific network
     interface.  (Bug#22195 (http://bugs.mysql.com/22195))

   * *MySQL Cluster*: The `Ndb_number_of_storage_nodes' system variable
     was renamed to `Ndb_number_of_data_nodes'.  (Bug#20848
     (http://bugs.mysql.com/20848))

   * *MySQL Cluster*: The `HELP' command in the Cluster management
     client now provides command-specific help. For example, `HELP
     RESTART' in `ndb_mgm' provides detailed information about the
     `RESTART' command.  (Bug#19620 (http://bugs.mysql.com/19620))

   * *MySQL Cluster*: A number of erroneous, misleading, or missing
     error messages have been corrected.  (Bug#17297
     (http://bugs.mysql.com/17297), Bug#19543
     (http://bugs.mysql.com/19543))

   * *MySQL Cluster*: Backup messages are no longer printed to the
     cluster log.

   * *MySQL Cluster*: Added the `--ndb-use-copying-alter-table' option
     to `mysqld' to provide a fallback in case of problems with online
     `ALTER TABLE' operations on `NDB' tables.

   * *Cluster API*: Two new NDB API methods -- `aggregate()' and
     `validate()' -- were added to the `NdbDictionary::Object::Table'
     class. See `Table::aggregate()'
     (http://dev.mysql.com/doc/ndbapi/en/class-table-aggregate.html),
     and `Table::validate()'
     (http://dev.mysql.com/doc/ndbapi/en/class-table-validate.html),
     for more information. This was done to rectify the following
     issues:

        * Under some conditions, the data distribution could become
          unbalanced in a MySQL Cluster with 2 or more node groups
          following the creation of a new table.

        * Data was stored unevenly between partitions due to all `BLOB'
          data being placed in partition 0.

     (Bug#21690 (http://bugs.mysql.com/21690))

   * The number of `InnoDB' threads is no longer limited to 1,000 on
     Windows.  (Bug#22268 (http://bugs.mysql.com/22268))

   * The `STATE' column of the `INFORMATION_SCHEMA.PROCESSLIST' table
     was increased from 30 to 64 characters to accommodate longer state
     values.  (Bug#21652 (http://bugs.mysql.com/21652))

   * `mysqldump' now has a `--flush-privileges' option. It causes
     `mysqldump' to emit a `FLUSH PRIVILEGES' statement after dumping
     the `mysql' database. This option should be used any time the dump
     contains the `mysql' database and any other database that depends
     on the data in the `mysql' database for proper restoration.
     (Bug#21424 (http://bugs.mysql.com/21424))

   * `mysqlslap' threads now try to connect up to 10 times if the
     initial connect attempt fails.  (Bug#21297
     (http://bugs.mysql.com/21297))

   * The output generated by the server when using the `--xml' option
     has changed with regard to null values. It now matches the output
     from `mysqldump `--xml' '. That is, a column containing a `NULL'
     value is now reported as

          <field name="COLUMN_NAME" xsi:nil="true" />

     whereas a column containing the string value `'NULL'' is reported
     as

          <field name="COLUMN_NAME">NULL</field>

     and a column containing an empty string is reported as

          <field name="COLUMN_NAME">>/field>

     (Bug#21263 (http://bugs.mysql.com/21263))

   * The `mysqld' and `mysqlmanager' manpages have been reclassified
     from volume 1 to volume 8.  (Bug#21220
     (http://bugs.mysql.com/21220))

   * `InnoDB' now honors `IGNORE INDEX'. Perviously using `IGNORE
     INDEX' in cases where an index sort would be slower than a
     filesort had no effect when used with `InnoDB' tables.  (Bug#21174
     (http://bugs.mysql.com/21174))

   * `TIMESTAMP' columns that are `NOT NULL' now are reported that way
     by `SHOW COLUMNS' and `INFORMATION_SCHEMA'.  (Bug#20910
     (http://bugs.mysql.com/20910))

   * Memory consumption of the `InnoDB' data dictionary cache was
     roughly halved by cleaning up the data structures.  (Bug#20877
     (http://bugs.mysql.com/20877))

   * The `BINARY' keyword now is forbidden as a data type attribute in
     stored routines (for example, `DECLARE v1 VARCHAR(25) BINARY'),
     because `DECLARE' does not support collations, and in this context
     `BINARY' specifies the binary collation of the variable's
     character set.  (Bug#20701 (http://bugs.mysql.com/20701))

   * The following statements now can be executed as prepared
     statements (using `PREPARE' plus `EXECUTE'):

          CACHE INDEX
          CHANGE MASTER
          CHECKSUM {TABLE | TABLES}
          {CREATE | RENAME | DROP} DATABASE
          {CREATE | RENAME | DROP} USER
          FLUSH {TABLE | TABLES | TABLES WITH READ LOCK | HOSTS | PRIVILEGES
            | LOGS | STATUS | MASTER | SLAVE | DES_KEY_FILE | USER_RESOURCES}
          GRANT
          REVOKE
          KILL
          LOAD INDEX INTO CACHE
          RESET {MASTER | SLAVE | QUERY CACHE}
          SHOW BINLOG EVENTS
          SHOW CREATE {PROCEDURE | FUNCTION | EVENT | TABLE | VIEW}
          SHOW {AUTHORS | CONTRIBUTORS | WARNINGS | ERRORS}
          SHOW {MASTER | BINARY} LOGS
          SHOW {MASTER | SLAVE} STATUS
          SLAVE {START | STOP}
          INSTALL PLUGIN
          UNINSTALL PLUGIN

     (Bug#20665 (http://bugs.mysql.com/20665))

   * In the `INFORMATION_SCHEMA.ROUTINES' table the
     `ROUTINE_DEFINITION' column now is defined as `NULL' rather than
     `NOT NULL'.  Also, `NULL' rather than the empty string is returned
     as the column value if the user does not have sufficient
     privileges to see the routine definition.  (Bug#20230
     (http://bugs.mysql.com/20230))

   * The `mysqldumpslow' script has been moved from client RPM packages
     to server RPM packages. This corrects a problem where
     `mysqldumpslow' could not be used with a client-only RPM install,
     because it depends on `my_print_defaults' which is in the server
     RPM.  (Bug#20216 (http://bugs.mysql.com/20216))

   * The MySQL distribution now compiles on UnixWare 7.13.  (Bug#20190
     (http://bugs.mysql.com/20190))

   * `configure' now defines the symbol `DBUG_ON' in `config.h' to
     indicate whether the source tree is configured to be compiled with
     debugging support.  (Bug#19517 (http://bugs.mysql.com/19517))

   * `TEXT' and `BLOB' columns do not support `DEFAULT' values.
     However, when a default of `''' was specified, the specification
     was silently ignored. This now results in a warning, or an error
     in strict mode.  (Bug#19498 (http://bugs.mysql.com/19498))

   * For `mysqlshow', if a database name argument contains wildcard
     characters (such as ` `_' ') but matches a single database name
     exactly, treat the name as a literal name. This allows a command
     such as `mysqlshow information_schema' work without having to
     escape the wildcard character.  (Bug#19147
     (http://bugs.mysql.com/19147))

   * The source distribution has been updated so that the UDF example
     can be compiled under Windows with CMake. See *Note
     udf-compiling::.  (Bug#19121 (http://bugs.mysql.com/19121))

   * The default value of the `tmp_table_size' system variable was
     lowered from 32MB to 16MB because it is bounded by the value of
     `max_heap_table_size', which has a default of 16MB.  (Bug#18875
     (http://bugs.mysql.com/18875))

   * Log table changes: By default, the log tables use the `CSV'
     storage engine, as before. But now the log tables can be altered
     to use the `MyISAM' storage engine. You cannot use `ALTER TABLE' to
     alter a log table that is in use. The log must be disabled first.
     No engines other than `CSV' or `MyISAM' are legal for the log
     tables. The use of `DROP TABLE' for log tables is similarly
     restricted: It cannot be used to drop a log table that is in use.
     The log must be disabled first. (These changes also correct a
     deadlock that occurred for an attempt to drop an in-use log table.)
     (Bug#18559 (http://bugs.mysql.com/18559))

   * Added the `--set-charset' option to `mysqlbinlog' to allow the
     character set to be specified for processing binary log files.
     (Bug#18351 (http://bugs.mysql.com/18351))

   * The `ExtractValue()' function now produces an error when passed an
     XML fragment that is not well-formed.

     (Previously, the function allowed invalid XML fragments to be
     used.)  (Bug#18201 (http://bugs.mysql.com/18201))

   * On Windows, typing Control-C while a query was running caused the
     `mysql' client to crash. Now it causes `mysql' to attempt to kill
     the current statement. If this cannot be done, or Control-C is
     typed again before the statement is killed, `mysql' exits.  (In
     other words, `mysql''s behavior with regard to Control-C is now
     the same as it is on Unix platforms.)  (Bug#17926
     (http://bugs.mysql.com/17926)) See also Bug#1989
     (http://bugs.mysql.com/1989)

   * The bundled yaSSL library licensing has added a FLOSS exception
     similar to MySQL to resolve licensing incompatibilities with
     MySQL. (See the `extra/yassl/FLOSS-EXCEPTIONS' file in a MySQL
     source distribution for details.)  (Bug#16755
     (http://bugs.mysql.com/16755))

   * `SHOW CREATE TABLE' now shows constraints for `InnoDB' tables.
     (Bug#16614 (http://bugs.mysql.com/16614))

   * `EXPLAIN EXTENDED' now shows a `filtered' column that is an
     estimated percentage of the examined rows that will be joined with
     the previous tables. This was added while dealing with a problem of
     MySQL choosing the wrong index for some queries.  (Bug#14940
     (http://bugs.mysql.com/14940))

   * The `mysql' client now allows `\l' in the `prompt' command
     argument to insert the current delimiter into the prompt.
     (Bug#14448 (http://bugs.mysql.com/14448))

   * The `mysql' client used the default character set if it
     automatically reconnected to the server, which is incorrect if the
     character set had been changed. To enable the character set to
     remain synchronized on the client and server, the `mysql' command
     `charset' (or `\C') that changes the default character set and now
     also issues a `SET NAMES' statement. The changed character set is
     used for reconnects.  (Bug#11972 (http://bugs.mysql.com/11972))

   * The `LEFT()' and `RIGHT()' functions return `NULL' if any argument
     is `NULL'.  (Bug#11728 (http://bugs.mysql.com/11728))

   * If a `DROP VIEW' statement named multiple views, it stopped with
     an error if a non-existent view was named and did not drop the
     remaining views. Now it continues on and reports an error at the
     end, similar to `DROP TABLE'.  (Bug#11551
     (http://bugs.mysql.com/11551))

   * For a successful dump, `mysqldump' now writes a SQL comment to the
     end of the dump file in the following format:

          -- Dump completed on YYYY-MM-DD hh:mm:ss

     (Bug#10877 (http://bugs.mysql.com/10877))

   * There were several issues regarding how `SHOW STATUS' affected
     some status variables and logging which could impact monitoring
     the MySQL Server. The behavior of this statement has been modified
     in two ways:

        * `SHOW STATUS' is no longer logged to the slow query log.

        * `SHOW STATUS' no longer updates any session status variables,
          except for `com_show_status'.

     However, `SHOW STATUS' continues to update _global_ status
     variables to allow monitoring of what the server is actually
     doing. This is because `SHOW STATUS' creates temporary tables that
     may affect performance if it is called excessively often.
     (Bug#10210 (http://bugs.mysql.com/10210)) See also Bug#19764
     (http://bugs.mysql.com/19764)

   * For spatial data types, the server formerly returned these as
     `VARSTRING' values with a binary collation. Now the server returns
     spatial values as `BLOB' values.  (Bug#10166
     (http://bugs.mysql.com/10166))

   * The `LOAD DATA FROM MASTER' and `LOAD TABLE FROM MASTER'
     statements are deprecated. See *Note load-data-from-master::, for
     recommended alternatives.  (Bug#9125 (http://bugs.mysql.com/9125),
     Bug#20596 (http://bugs.mysql.com/20596), Bug#14399
     (http://bugs.mysql.com/14399), Bug#12187
     (http://bugs.mysql.com/12187), Bug#15025
     (http://bugs.mysql.com/15025), Bug#18822
     (http://bugs.mysql.com/18822))

   * For the `mysql' client, typing Control-C causes `mysql' to attempt
     to kill the current statement. If this cannot be done, or
     Control-C is typed again before the statement is killed, `mysql'
     exits.  Previously, Control-C caused `mysql' to exit in all cases.
     (Bug#1989 (http://bugs.mysql.com/1989))

   * It is no longer possible to create partitioned tables using the
     `CSV' storage engine.

   * Binary MySQL distributions no longer include a `mysqld-max'
     server. Instead, distributions contain a binary that includes the
     features previously included in the `mysqld-max' binary.

   * `SHOW STATUS' is no longer logged to the slow query log.

   * Program Database files (extension `pdf') are now included by
     default in Windows distributions. These can be used to help
     diagnose problems with `mysqld' and other tools. See *Note
     debugging-server::.

   * `INFORMATION_SCHEMA' contains new tables, `GLOBAL_STATUS',
     `SESSION_STATUS', `GLOBAL_VARIABLES', and `SESSION_VARIABLES',
     that correspond to the output from the `SHOW {GLOBAL|SESSION}
     STATUS' and `SHOW {GLOBAL|SESSION} VARIABLES' statements.

   * `SHOW STATUS' no longer updates any session status variables,
     except for `com_show_status'.

   * A new system variable, `lc_time_names', specifies the locale that
     controls the language used to display day and month names and
     abbreviations. This variable affects the output from the
     `DATE_FORMAT()', `DAYNAME()' and `MONTHNAME()' functions. See
     *Note locale-support::.

   * Using `--with-debug' to configure MySQL with debugging support
     enables you to use the `--debug="d,parser_debug"' option when you
     start the server. This causes the Bison parser that is used to
     process SQL statements to dump a parser trace to the server's
     standard error output. Typically, this output is written to the
     error log.

   * The bundled yaSSL library was upgraded to version 1.3.7.

   * The Instance Manager `--passwd' option has been renamed to
     `--print-password-line'. Other options were added to enable
     management of the IM password file from the command line:
     `--add-user', `--drop-user', `--edit-user', `--list-users',
     `--check-password-file', `--clean-password-file', `--username',
     and `--password'.  The `--mysql-safe-compatible' option was added
     to cause the Instance Manner to act similarly to `mysqld_safe'.

   * Added the `SHOW CONTRIBUTORS' statement.

   * The general query log and slow query logs now can be enabled or
     disabled at runtime with the `general_log' and `slow_query_log'
     system variables, and the name of the log files can be changed by
     setting the `general_log_file' and `slow_query_log_file' system
     variables. See *Note query-log::, and *Note slow-query-log::.

   * The default binary log format (as used during replication) is now
     Mixed based, automatically using a combination of row-based and
     statement based log events as appropriate.

Bugs fixed:

   * *Security Fix*: A stored routine created by one user and then made
     accessible to a different user using `GRANT EXECUTE' could be
     executed by that user with the privileges of the routine's definer.
     (Bug#18630 (http://bugs.mysql.com/18630), CVE-2006-4227
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-4227))

   * *Security Fix*: On Linux, and possibly other platforms using
     case-sensitive filesystems, it was possible for a user granted
     rights on a database to create or access a database whose name
     differed only from that of the first by the case of one or more
     letters.  (Bug#17647 (http://bugs.mysql.com/17647), CVE-2006-4226
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-4226))

   * *Security Fix*: If a user has access to `MyISAM' table T, that
     user can create a `MERGE' table M that accesses T. However, if the
     user's privileges on T are subsequently revoked, the user can
     continue to access T by doing so through M. If this behavior is
     undesirable, you can start the server with the new `--skip-merge'
     option to disable the `MERGE' storage engine.  (Bug#15195
     (http://bugs.mysql.com/15195), CVE-2006-4031
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-4031))

   * *Incompatible Change*: For `utf8' columns, the full-text parser
     incorrectly considered several non-word punctuation and whitespace
     characters as word characters, causing some searches to return
     incorrect results.

     The fix involves a change to the full-text parser, so any tables
     that have `FULLTEXT' indexes on `utf8' columns must be repaired
     with `REPAIR TABLE':

          REPAIR TABLE TBL_NAME QUICK;

     (Bug#19580 (http://bugs.mysql.com/19580))

   * *MySQL Cluster*: *Packaging*: The `ndb_mgm' program was included
     in both the `MySQL-ndb-tools' and `MySQL-ndb-management' RPM
     packages, resulting in a conflict if both were installed. Now
     `ndb_mgm' is included only in `MySQL-ndb-tools'.  (Bug#21058
     (http://bugs.mysql.com/21058))

   * *MySQL Cluster*: *Replication*: A `DELETE FROM table' with no
     `WHERE' clause (deleting all rows) running concurrently with
     `INSERT' statements on a storage engine with row-level locking
     (such as `NDB') could produce inconsistent results when using
     statement-based replication.  (Bug#19066
     (http://bugs.mysql.com/19066))

   * *MySQL Cluster*: (NDB API): Inacivity timeouts for scans were not
     correctly handled.  (Bug#23107 (http://bugs.mysql.com/23107))

   * *MySQL Cluster*: Inserting into an `NDB' table failed when the
     table had no primary key but had a unique key added after table
     was created on one or more `NOT NULL' columns.  This occurred when
     the unique key had been adding using either `ALTER TABLE' or
     `CREATE UNIQUE KEY'.  (Bug#22838 (http://bugs.mysql.com/22838))

   * *MySQL Cluster*: (NDB API): Attempting to read a nonexistent tuple
     using `Commit' mode for `NdbTransaction::execute()' caused node
     failures.  (Bug#22672 (http://bugs.mysql.com/22672))

   * *MySQL Cluster*: The `--help' output from `NDB' binaries did not
     include file-related options.  (Bug#21994
     (http://bugs.mysql.com/21994))

   * *MySQL Cluster*: Setting `TransactionDeadlockDetectionTimeout' to
     a value greater than 12000 would cause scans to deadlock, time
     out, fail to release scan records, until the cluster ran out of
     scan records and stopped processing.  (Bug#21800
     (http://bugs.mysql.com/21800))

   * *MySQL Cluster*: A scan timeout returned Error 4028 (`Node failure
     caused abort of transaction') instead of Error 4008 (`Node failure
     caused abort of transaction...').  (Bug#21799
     (http://bugs.mysql.com/21799))

   * *MySQL Cluster*: The node recovery algorithm was missing a version
     check for tables in the `ALTER_TABLE_COMMITTED' state (as opposed
     to the `TABLE_ADD_COMMITTED' state, which has the version check).
     This could cause inconsistent schemas across nodes following node
     recovery.  (Bug#21756 (http://bugs.mysql.com/21756))

   * *MySQL Cluster*: A memory leak occurred when running `ndb_mgm -e
     "SHOW"'.  (Bug#21670 (http://bugs.mysql.com/21670))

   * *MySQL Cluster*: The server provided a non-descriptive error
     message when encountering a fatally corrupted REDO log.
     (Bug#21615 (http://bugs.mysql.com/21615))

   * *MySQL Cluster*: The output for the `--help' option used with
     `NDB' executable programs (such as `ndbd', `ndb_mgm',
     `ndb_restore', `ndb_config', and others mentioned in *Note
     mysql-cluster-utilities::) referred to the `Ndb.cfg' file, instead
     of to `my.cnf'.  (Bug#21585 (http://bugs.mysql.com/21585))

   * *MySQL Cluster*: A partial rollback could lead to node restart
     failures.  (Bug#21536 (http://bugs.mysql.com/21536))

   * *MySQL Cluster*: Partition distribution keys were updated only for
     the primary and starting replicas during node recovery. This could
     lead to node failure recovery for clusters having an odd number of
     replicas.

     *Note*:

     We recommend values for `NumberOfReplicas' that are even powers of
     2, for best results.

     (Bug#21535 (http://bugs.mysql.com/21535))

   * *MySQL Cluster*: The `ndb_mgm' management client did not set the
     exit status on errors, always returning 0 instead.  (Bug#21530
     (http://bugs.mysql.com/21530))

   * *MySQL Cluster*: The failure of a unique index read due to an
     invalid schema version could be handled incorrectly in some cases,
     leading to unpredictable results.  (Bug#21384
     (http://bugs.mysql.com/21384))

   * *MySQL Cluster*: Attempting to create an `NDB' table on a MySQL
     server with an existing non-Cluster table with the same name in
     the same database could result in data loss or corruption. Now, if
     such a table is encountered during autodiscovery, a warning is
     written to the error log of the affected `mysqld', and the local
     table is overwritten.  (Bug#21378 (http://bugs.mysql.com/21378))

   * *MySQL Cluster*: Cluster logs were not rotated following the first
     rotation cycle.  (Bug#21345 (http://bugs.mysql.com/21345))

   * *MySQL Cluster*: In a cluster with more than 2 replicas, a manual
     restart of one of the data nodes could fail and cause the other
     nodes in the same node group to shut down.  (Bug#21213
     (http://bugs.mysql.com/21213))

   * *MySQL Cluster*: The `ndb_size.pl' script did not account for
     `TEXT' and `BLOB' column values correctly.  (Bug#21204
     (http://bugs.mysql.com/21204))

   * *MySQL Cluster*: Some queries involving joins on very large `NDB'
     tables could crash the MySQL server.  (Bug#21059
     (http://bugs.mysql.com/21059))

   * *MySQL Cluster*: Condition pushdown did not work correctly with
     `DATETIME' columns.  (Bug#21056 (http://bugs.mysql.com/21056))

   * *MySQL Cluster*: Responses to the ALL DUMP 1000 management client
     command were printed multiple times in the cluster log for each
     cluster node.  (Bug#21044 (http://bugs.mysql.com/21044))

   * *MySQL Cluster*: The message `Error 0 in readAutoIncrementValue():
     no Error' was written to the error log whenever `SHOW TABLE
     STATUS' was performed on a Cluster table that did not have an
     `AUTO_INCREMENT' column.  (Bug#21033 (http://bugs.mysql.com/21033))

   * *MySQL Cluster*: Restarting a data node while DDL operations were
     in progress on the cluster could cause other data nodes to fail.
     This could also lead to `mysqld' hanging or crashing under some
     circumstances.  (Bug#21017 (http://bugs.mysql.com/21017),
     Bug#21050 (http://bugs.mysql.com/21050))

   * *MySQL Cluster*: In some situations with a high disk-load, writing
     of the redo log could hang, causing a crash with the error message
     `GCP STOP detected'.  (Bug#20904 (http://bugs.mysql.com/20904))

   * *MySQL Cluster*: A race condition could in some cirumstances
     following a `DROP TABLE'.  (Bug#20897
     (http://bugs.mysql.com/20897))

   * *MySQL Cluster*: Under some circumstances, local checkpointing
     would hang, keeping any unstarted nodes from being started.
     (Bug#20895 (http://bugs.mysql.com/20895))

   * *MySQL Cluster*: When the redo buffer ran out of space, a `Pointer
     too large' error was raised and the cluster could become unusable
     until restarted with `--initial'.  (Bug#20892
     (http://bugs.mysql.com/20892))

   * *MySQL Cluster*: A vague error message was returned when reading
     both schema files during a restart of the cluster.  (Bug#20860
     (http://bugs.mysql.com/20860))

   * *MySQL Cluster*: The repeated creating and dropping of a table
     would eventually lead to `NDB' Error 826, `Too many tables and
     attributes ... Insufficient space'.  (Bug#20847
     (http://bugs.mysql.com/20847))

   * *MySQL Cluster*: When attempting to restart the cluster following
     a data import, the cluster failed during Phase 4 of the restart
     with `Error 2334: Job buffer congestion'.  (Bug#20774
     (http://bugs.mysql.com/20774))

   * *MySQL Cluster*: `REPLACE' statements did not work correctly on an
     `NDB' table having both a primary key and a unique key. In such
     cases, proper values were not set for columns which were not
     explicitly referenced in the statement.  (Bug#20728
     (http://bugs.mysql.com/20728))

   * *MySQL Cluster*: The server did not honor the value set for
     `ndb_cache_check_time' in the `my.cnf' file.  (Bug#20708
     (http://bugs.mysql.com/20708))

   * *MySQL Cluster*: Truncating a table on one `mysqld' caused other
     `mysqld' processes connected to the cluster to return `ERROR 1412
     (HY000): Table definition has changed, please retry transaction'
     on subsequent queries.  (Bug#20705 (http://bugs.mysql.com/20705))

   * *MySQL Cluster*: Using an invalid node ID with the management
     client `STOP' command could cause `ndb_mgm' to hang.  (Bug#20575
     (http://bugs.mysql.com/20575))

   * *MySQL Cluster*: Renaming of table columns was not supported as
     fast a `ALTER TABLE' for NDB tables.  (Bug#20456
     (http://bugs.mysql.com/20456))

   * *MySQL Cluster*: `ndb_size.pl' and `ndb_error_reporter' were
     missing from RPM packages.  (Bug#20426
     (http://bugs.mysql.com/20426))

   * *MySQL Cluster*: Running `ndbd' `--nowait-nodes=ID ' where ID was
     the node ID of a node that was already running would fail with an
     invalid error message.  (Bug#20419 (http://bugs.mysql.com/20419))

   * *MySQL Cluster*: Data nodes added while the cluster was running in
     single user mode were all assigned node ID 0, which could later
     cause multiple node failures. Adding nodes while in single user
     mode is no longer possible.  (Bug#20395
     (http://bugs.mysql.com/20395))

   * *MySQL Cluster*: The `ndb_mgm' client command `ALL CLUSTERLOG
     STATISTICS=15' had no effect.  (Bug#20336
     (http://bugs.mysql.com/20336))

   * *MySQL Cluster*: (Direct APIs): `NdbScanOperation::readTuples()'
     and `NdbIndexScanOperation::readTuples()' ignored the BATCH
     parameter.  (Bug#20252 (http://bugs.mysql.com/20252))

   * *MySQL Cluster*: A node failure during a scan could sometime cause
     the node to crash when restarting too quickly following the
     failure.  (Bug#20197 (http://bugs.mysql.com/20197))

   * *MySQL Cluster*: The failure of a data node when preparing to
     commit a transaction (that is, while the node's status was
     `CS_PREPARE_TO_COMMIT') could cause the failure of other cluster
     data nodes.  (Bug#20185 (http://bugs.mysql.com/20185))

   * *MySQL Cluster*: `SHOW ENGINE NDB STATUS' could sometimes return
     an incorrect value of `0' for the latest epoch, which could cause
     problems with synchronizing the binlog.  (Bug#20142
     (http://bugs.mysql.com/20142))

   * *MySQL Cluster*: An internal formatting error caused some
     management client error messages to be unreadable.  (Bug#20016
     (http://bugs.mysql.com/20016))

   * *MySQL Cluster*: Creating tables with variable-size columns caused
     `DataMemory' to be used but not freed when the tables were dropped.
     (Bug#20007 (http://bugs.mysql.com/20007))

   * *MySQL Cluster*: Renaming a table in such a way as to move it to a
     different database failed to move the table's indexes.  (Bug#19967
     (http://bugs.mysql.com/19967))

   * *MySQL Cluster*: Running management client commands while `mgmd'
     was in the process of disconnecting could cause the management
     server to fail.  (Bug#19932 (http://bugs.mysql.com/19932))

   * *MySQL Cluster*: Under certain conditions, a starting node could
     miss transactions, leading to inconsistencies between the primary
     and backup replicas.  (Bug#19929 (http://bugs.mysql.com/19929))

   * *MySQL Cluster*: An uncommitted row could sometimes be
     checkpointed and thus incorrectly included in a backup.
     (Bug#19928 (http://bugs.mysql.com/19928))

   * *MySQL Cluster*: In some cases where `SELECT COUNT(*)' from an
     `NDB' table should have yielded an error, `MAX_INT' was returned
     instead.  (Bug#19914 (http://bugs.mysql.com/19914))

   * *MySQL Cluster*: `TEXT' columns in Cluster tables having both an
     explicit primary key and a unique key were not correctly updated
     by `REPLACE' statements.  (Bug#19906 (http://bugs.mysql.com/19906))

   * *MySQL Cluster*: The cluster's data nodes failed while trying to
     load data when `NoOfFrangmentLogFiles' was set equal to 1.
     (Bug#19894 (http://bugs.mysql.com/19894))

   * *MySQL Cluster*: Following the restart of a management node, the
     Cluster management client did not automatically reconnect.
     (Bug#19873 (http://bugs.mysql.com/19873))

   * *MySQL Cluster*: Restoring a backup with `ndb_restore' failed when
     the backup had been taken from a cluster whose `DataMemory' had
     been completely used up.  (Bug#19852 (http://bugs.mysql.com/19852))

   * *MySQL Cluster*: Error messages given when trying to make online
     changes to parameters such as `NoOfReplicas' that can only be
     changed via a complete shutdown and restart of the cluster did not
     indicate the true nature of the problem.  (Bug#19787
     (http://bugs.mysql.com/19787))

   * *MySQL Cluster*: Under some circumstances, repeated DDL operations
     on one `mysqld' could cause failure of a second `mysqld' attached
     to the same cluster.  (Bug#19770 (http://bugs.mysql.com/19770))

   * *MySQL Cluster*: `ndb_restore' did not always make clear that it
     had recovered successfully from temporary errors while restoring a
     cluster backup.  (Bug#19651 (http://bugs.mysql.com/19651))

   * *MySQL Cluster*: Resources for unique indexes on Cluster table
     columns were incorrectly allocated, so that only one-fourth as
     many unique indexes as indicated by the value of
     `UniqueHashIndexes' could be created.  (Bug#19623
     (http://bugs.mysql.com/19623))

   * *MySQL Cluster*: `LOAD DATA LOCAL' failed to ignore duplicate keys
     in Cluster tables.  (Bug#19496 (http://bugs.mysql.com/19496))

   * *MySQL Cluster*: For `ndb_mgmd', Valgrind revealed problems with a
     memory leak and a dependency on an uninitialized variable.
     (Bug#19318 (http://bugs.mysql.com/19318), Bug#20333
     (http://bugs.mysql.com/20333))

   * *MySQL Cluster*: A `DELETE' of many rows immediately followed by
     an `INSERT' on the same table could cause the `ndbd' process on
     the backup replica to crash.  (Bug#19293
     (http://bugs.mysql.com/19293))

   * *MySQL Cluster*: An excessive number of `ALTER TABLE' operations
     could cause the cluster to fail with `NDB' error code 773 (`Out of
     string memory, please modify StringMemory').  (Bug#19275
     (http://bugs.mysql.com/19275))

   * *MySQL Cluster*: A problem with error handling when
     `ndb_use_exact_count' was enabled could lead to incorrect values
     returned from queries using `COUNT()'. A warning is now returned
     in such cases.  (Bug#19202 (http://bugs.mysql.com/19202))

   * *MySQL Cluster*: In rare situations with resource shortages, a
     crash could result from insufficient `IndexScanOperations'.
     (Bug#19198 (http://bugs.mysql.com/19198))

   * *MySQL Cluster*: Running out of `DataMemory' could sometimes crash
     `ndbd' and `mysqld' processes.  (Bug#19185
     (http://bugs.mysql.com/19185))

   * *MySQL Cluster*: It was possible to use port numbers greater than
     65535 for `ServerPort' in the `config.ini' file.  (Bug#19164
     (http://bugs.mysql.com/19164))

   * *MySQL Cluster*: `ndb_mgm -e show | head' would hang after
     displaying the first 10 lines of output.  (Bug#19047
     (http://bugs.mysql.com/19047))

   * *MySQL Cluster*: The error returned by the cluster when too many
     nodes were defined did not make clear the nature of the problem.
     (Bug#19045 (http://bugs.mysql.com/19045))

   * *MySQL Cluster*: The management client `ALL STOP' command shut
     down `mgmd' processes (as well as `ndbd' processes).  (Bug#18966
     (http://bugs.mysql.com/18966))

   * *MySQL Cluster*: `TRUNCATE TABLE' failed to reset the
     `AUTO_INCREMENT' counter.  (Bug#18864
     (http://bugs.mysql.com/18864))

   * *MySQL Cluster*: Restarting a failed node could sometimes crash
     the cluster.  (Bug#18782 (http://bugs.mysql.com/18782))

   * *MySQL Cluster*: Trying to create or drop a table while a node was
     restarting caused the node to crash. This is now handled by
     raising an error.  (Bug#18781 (http://bugs.mysql.com/18781))

   * *MySQL Cluster*: Repeated `CREATE' - `INSERT' - `DROP' operations
     tables could in some circumstances cause the MySQL table
     definition cache to become corrupt, so that some `mysqld'
     processes could access table information but others could not.
     (Bug#18595 (http://bugs.mysql.com/18595))

   * *MySQL Cluster*: A `CREATE TABLE' statement involving foreign key
     constraints raised an error rather than being silently ignored
     (see *Note create-table::).

     This bug affected Cluster in MySQL 5.1 only.  (Bug#18483
     (http://bugs.mysql.com/18483))

   * *MySQL Cluster*: The server failed with a non-descriptive error
     message when out of data memory.  (Bug#18475
     (http://bugs.mysql.com/18475))

   * *MySQL Cluster*: For `NDB' and possibly `InnoDB' tables, a `BEFORE
     UPDATE' trigger could insert incorrect values.  (Bug#18437
     (http://bugs.mysql.com/18437))

   * *MySQL Cluster*: The `DATA_LENGTH' and `AVG_ROW_LENGTH' columns of
     the `INFORMATION_SCHEMA.TABLES' table did not report the size of
     variable-width column values correctly.

     See *Note tables-table::, for more information.  (Bug#18413
     (http://bugs.mysql.com/18413))

   * *MySQL Cluster*: `SELECT ... FOR UPDATE' failed to lock the
     selected rows.  (Bug#18184 (http://bugs.mysql.com/18184))

   * *MySQL Cluster*: (Disk Data): Deletes from Disk Data tables used a
     non-optimal scan to find the rows to be deleted, resulting in poor
     performance. The fix causes disk order rather than memory order to
     be used, and can improve performance of Disk Data deletes by up to
     ~300% in some cases.  (Bug#17929 (http://bugs.mysql.com/17929))

   * *MySQL Cluster*: `perror' did not properly report `NDB' error
     codes.  (Bug#16561 (http://bugs.mysql.com/16561))

   * *MySQL Cluster*: A problem with takeover during a system restart
     caused ordered indexes to be rebuilt incorrectly. This also
     adversely affected MySQL Cluster Replication.  (Bug#15303
     (http://bugs.mysql.com/15303))

   * *MySQL Cluster*: A cluster data node could crash when an ordered
     index became full before the table containing the index was full.
     (Bug#14935 (http://bugs.mysql.com/14935))

   * *MySQL Cluster*: The management client `ALL STATUS' command could
     sometimes report the status of some data nodes incorrectly.
     (Bug#13985 (http://bugs.mysql.com/13985))

   * *MySQL Cluster*: New `mysqld' processes were allowed to connect
     without a restart of the cluster, causing the cluster to crash.
     (Bug#13266 (http://bugs.mysql.com/13266))

   * *MySQL Cluster*: Cluster system status variables were not updated
     properly.  (Bug#11459 (http://bugs.mysql.com/11459))

   * *MySQL Cluster*: (NDBAPI): Update operations on blobs were not
     checked for illegal operations.

     *Note*:

     Read locks with blob update operations are now upgraded from read
     committed to read shared.

   * *MySQL Cluster*: (Replication): A node failure could send
     duplicate events, causing a `mysqld' replicating tables containing
     `BLOB's to crash.

   * *MySQL Cluster*: The loss of one or more data nodes could
     sometimes cause `ndb_mgmd' to use a high amount of CPU (15 percent
     or more, as opposed to 1 to 2 percent normally).

   * *Partitioning*: Old partition and subpartition files were not
     always removed following `ALTER TABLE ... REORGANIZE PARTITION'
     statements.  (Bug#20770 (http://bugs.mysql.com/20770))

   * *Disk Data*: On some platforms, `ndbd' compiled with `gcc' 4 would
     crash when attempting to run `CREATE LOGFILE GROUP'.  (Bug#21981
     (http://bugs.mysql.com/21981))

   * *Disk Data*: Trying to create a Disk Data table using a nonexistent
     tablespace or to drop a nonexistent data file from a tablespace
     produced an uninformative error message.  (Bug#21751
     (http://bugs.mysql.com/21751))

   * *Disk Data*: Errors could occur when dropping a data file during a
     node local checkpoint.  (Bug#21710 (http://bugs.mysql.com/21710))

   * *Disk Data*: Creating a tablespace and log file group, then
     attempting to restart the cluster without using the `--initial'
     option and without having created any Disk Data tables could cause
     a forced shutdown of the cluster and raise a configuration error.
     (Bug#21172 (http://bugs.mysql.com/21172))

   * *Disk Data*: `mysqldump' did not back up tablespace or log file
     group information for Disk Data tables correctly.

     Specifically, `UNDO_BUFFER_SIZE' and `INITIAL_SIZE' values were
     misreported. This meant that trying to restore from such a backup
     would produce error 1296: `Got error 1504 'Out of logbuffer memory'
     from NDB'.  (Bug#20809 (http://bugs.mysql.com/20809))

   * *Disk Data*: Running a large number of scans on Disk Data could
     cause subsequent scans to perform poorly.  (Bug#20334
     (http://bugs.mysql.com/20334))

   * *Disk Data*: `INFORMATION_SCHEMA.FILES' records for UNDO files
     showed incorrect values in the `EXTENT_SIZE', `FREE_EXTENTS', and
     `TOTAL_EXTENTS' columns.  (Bug#20073 (http://bugs.mysql.com/20073))

   * *Disk Data*: A data file created for one tablespace could be
     dropped using `ALTER TABLESPACE ... DROP DATAFILE' using a
     different tablespace.  (Bug#20053 (http://bugs.mysql.com/20053))

   * *Disk Data*: Trying to create Disk Data tables when running the
     cluster in diskless mode caused cluster data nodes to crash.

     *Note*:

     Disk Data tables are now disabled when running in diskless mode.

     (Bug#20008 (http://bugs.mysql.com/20008))

   * *Disk Data*: An issue with disk allocation could sometimes cause a
     forced shutdown of the cluster when running a mix of memory and
     Disk Data tables.  (Bug#18780 (http://bugs.mysql.com/18780))

   * *Disk Data*: The failure of a `CREATE TABLESPACE' or `CREATE
     LOGFILE GROUP' statement did not revert all changes made prior to
     the point of failure.  (Bug#16341 (http://bugs.mysql.com/16341))

   * *Cluster Replication*: In some cases, a large number of MySQL
     servers sending requests to the cluster simultaneously could cause
     the cluster to crash.  This could also be triggered by many `NDB'
     API clients making simultaneous event subscriptions or
     unsubscriptions.  (Bug#20683 (http://bugs.mysql.com/20683))

   * *Cluster Replication*: One or more of the `mysqld' processes could
     fail when subjecting a Cluster replication setup with multiple
     `mysqld' processes on both the master and slave clusters to high
     loads.  (Bug#19768 (http://bugs.mysql.com/19768))

   * *Cluster Replication*: Data definition and data manipulation
     statements on different tables were not serialised correctly in
     the binlog. For example, there was no guarantee that a `CREATE
     TABLE' statement and an update on a different table would occur in
     the same order in the binlog as they did on the cluster being
     replicated.  (Bug#18947 (http://bugs.mysql.com/18947))

   * *Cluster API*: The `storage/ndb' directory was missing from the
     server binary distribution, making it impossible to compile `NDB'
     API and MGM API applications. This directory can be found as
     `/usr/include/storage/ndb' after installing that distribution.
     (Bug#21955 (http://bugs.mysql.com/21955))

   * *Cluster API*: Invoking the MGM API function
     `ndb_mgm_listen_event()' caused a memory leak.  (Bug#21671
     (http://bugs.mysql.com/21671))

   * *Cluster API*: The inclusion of `my_config.h' in `NdbApi.h'
     required anyone wishing to write NDB API applications against
     MySQL 5.1 to have a complete copy of the 5.1 sources.  (Bug#21253
     (http://bugs.mysql.com/21253))

   * *Cluster API*: The MGM API function `ndb_logevent_get_fd()' was
     not implemented.  (Bug#21129 (http://bugs.mysql.com/21129))

   * *Cluster API*: The `NdbOperation::getBlobHandle()' method, when
     called with the name of a nonexistent column, caused a
     segmentation fault.  (Bug#21036 (http://bugs.mysql.com/21036))

   * `ALTER EVENT' statements including only a `COMMENT' clause failed
     with a syntax error on two platforms: Linux for S/390, and OS X
     10.4 for 64-bit PPC.  (Bug#23423 (http://bugs.mysql.com/23423))

   * When `event_scheduler' was set to `DISABLED', its value was not
     displayed correctly by `SHOW VARIABLES' or `SELECT
     @@global.event_scheduler'.  (Bug#22662
     (http://bugs.mysql.com/22662))

   * `BIT' columns were not replicated properly under row-based
     replication.  (Bug#22550 (http://bugs.mysql.com/22550))

   * `ALTER EVENT' in the body of a stored procedure led to a crash
     when the procedure was called. This affected only those `ALTER
     EVENT' statements which changed the interval of the event.
     (Bug#22397 (http://bugs.mysql.com/22397))

   * The optimizer could make an incorrect index choice for indexes
     with a skewed key distribution.  (Bug#22393
     (http://bugs.mysql.com/22393))

   * Deleting entries from a large `MyISAM' index could cause index
     corruption when it needed to shrink. Deletes from an index can
     happen when a record is deleted, when a key changes and must be
     moved, and when a key must be un-inserted because of a duplicate
     key. This can also happen in `REPAIR TABLE' when a duplicate key
     is found and in `myisamchk' when sorting the records by an index.
     (Bug#22384 (http://bugs.mysql.com/22384))

   * Instance Manager had a race condition involving ` mysqld' PID file
     removal.  (Bug#22379 (http://bugs.mysql.com/22379))

   * yaSSL had a conflicting definition for `socklen_t' on hurd-i386
     systems.  (Bug#22326 (http://bugs.mysql.com/22326))

   * Conversion of values inserted into a `BIT' column could affect
     adjacent columns.  (Bug#22271 (http://bugs.mysql.com/22271))

   * Some Linux-x86_64-icc packages (of previous releases) mistakenly
     contained 32-bit binaries. Only `ICC' builds are affected, not
     `gcc' builds. Solaris and FreeBSD x86_64 builds are not affected.
     (Bug#22238 (http://bugs.mysql.com/22238))

   * `mysql_com.h' unnecessarily referred to the `ulong' type.
     (Bug#22227 (http://bugs.mysql.com/22227))

   * The source distribution would not build on Windows due to a
     spurious dependency on `ib_config.h'.  (Bug#22224
     (http://bugs.mysql.com/22224))

   * Execution of a prepared statement that uses an `IN' subquery with
     aggregate functions in the `HAVING' clause could cause a server
     crash.  (Bug#22085 (http://bugs.mysql.com/22085))

   * The `CSV' storage engine failed to detect some table corruption.
     (Bug#22080 (http://bugs.mysql.com/22080))

   * Using `GROUP_CONCAT()' on the result of a subquery in the `FROM'
     clause that itself used `GROUP_CONCAT()' could cause a server
     crash.  (Bug#22015 (http://bugs.mysql.com/22015))

   * Running `SHOW MASTER LOGS' at the same time as binary log files
     were being switched would cause `mysqld' to hang.  (Bug#21965
     (http://bugs.mysql.com/21965))

   * `libmysqlclient' defined a symbol `BN_bin2bn' which belongs to
     OpenSSL. This could break applications that also linked against
     OpenSSL's `libcrypto' library. The fix required correcting an
     error in a build script that was failing to add rename macros for
     some functions.  (Bug#21930 (http://bugs.mysql.com/21930))

   * `character_set_results' can be `NULL' to signify `no conversion,'
     but some code did not check for `NULL', resulting in a server
     crash.  (Bug#21913 (http://bugs.mysql.com/21913))

   * A misleading error message was displayed when attempting to define
     a unique key that was not valid for a partitioned table.
     (Bug#21862 (http://bugs.mysql.com/21862))

   * A query that used `GROUP BY' and an `ALL' or `ANY' quantified
     subquery in a `HAVING' clause could trigger an assertion failure.
     (Bug#21853 (http://bugs.mysql.com/21853))

   * An `InnoDB' mutex was not aquired and released under the same
     condition, leading to deadlock in some rare situations involving
     XA transactions.  (Bug#21833 (http://bugs.mysql.com/21833))

   * A `NUL' byte within a prepared statement string caused the rest of
     the string not to be written to the query log, allowing logging to
     be bypassed.  (Bug#21813 (http://bugs.mysql.com/21813))

   * `COUNT(*)' queries with `ORDER BY' and `LIMIT' could return the
     wrong result.

     *Note*:

     This problem was introduced by the fix for Bug#9676
     (http://bugs.mysql.com/9676), which limited the rows stored in a
     temporary table to the `LIMIT' clause. This optimization is not
     applicable to non-group queries with aggregate functions. The
     current fix disables the optimization in such cases.

     (Bug#21787 (http://bugs.mysql.com/21787))

   * Using `DROP TABLE' with concurrent queries causes `mysqld' to
     crash.  (Bug#21784 (http://bugs.mysql.com/21784))

   * `INSERT ... SELECT' sometimes generated a spurious `Column count
     doesn't match value count' error.  (Bug#21774
     (http://bugs.mysql.com/21774))

   * `UPGRADE' was treated as a reserved word, although it is not.
     (Bug#21772 (http://bugs.mysql.com/21772))

   * A function result in a comparison was replaced with a constant by
     the optimizer under some circumstances when this optimization was
     invalid.  (Bug#21698 (http://bugs.mysql.com/21698))

   * Selecting from `INFORMATION_SCHEMA.FILES' could crash the server.
     (Bug#21676 (http://bugs.mysql.com/21676))

   * Errors could be generated during the execution of certain prepared
     statements that ran queries on partitioned tables.  (Bug#21658
     (http://bugs.mysql.com/21658))

   * The presence of a subquery in the `ON' clause of a join in a view
     definition prevented the `MERGE' algorithm from being used for the
     view in cases where it should be allowed.  (Bug#21646
     (http://bugs.mysql.com/21646))

   * When records are merged from the insert buffer and the page needs
     to be reorganized, `InnoDB' used incorrect column length
     information when interpreting the records of the page. This caused
     a server crash due to apparent corruption of secondary indexes in
     `ROW_FORMAT=COMPACT' that contain prefix indexes of fixed-length
     columns. Data files should not be corrupted, but the crash was
     likely to repeat every time the server was restarted.  (Bug#21638
     (http://bugs.mysql.com/21638))

   * For character sets having a `mbmaxlen' value of 2, any `ALTER
     TABLE' statement changed `TEXT' columns to `MEDIUMTEXT'.
     (Bug#21620 (http://bugs.mysql.com/21620))

   * `mysql' displayed an empty string for `NULL' values.  (Bug#21618
     (http://bugs.mysql.com/21618))

   * Selecting from a `MERGE' table could result in a server crash if
     the underlying tables had fewer indexes than the `MERGE' table
     itself.  (Bug#21617 (http://bugs.mysql.com/21617), Bug#22937
     (http://bugs.mysql.com/22937))

   * A loaded storage engine plugin did not load after a server restart.
     (Bug#21610 (http://bugs.mysql.com/21610))

   * For `INSERT ... ON DUPLICATE KEY UPDATE', use of `VALUES(COL_NAME)'
     within the `UPDATE' clause sometimes was handled incorrectly.
     (Bug#21555 (http://bugs.mysql.com/21555))

   * Subqueries with aggregate functions but no `FROM' clause could
     return incorrect results.  (Bug#21540
     (http://bugs.mysql.com/21540))

   * `mysqldump' incorrectly tried to use `LOCK TABLES' for tables in
     the `INFORMATION_SCHEMA' database.  (Bug#21527
     (http://bugs.mysql.com/21527))

   * The server could crash for the second execution of a function
     containing a `SELECT' statement that uses an aggregating `IN'
     subquery.  (Bug#21493 (http://bugs.mysql.com/21493))

   * Memory overruns could occur for certain kinds of subqueries.
     (Bug#21477 (http://bugs.mysql.com/21477))

   * A `DATE' can be represented as an integer (such as `20060101') or
     as a string (such as `'2006.01.01''). When a `DATE' (or `TIME')
     column is compared in one `SELECT' against both representations,
     constant propagation by the optimizer led to comparison of `DATE'
     as a string against `DATE' as an integer. This could result in
     integer comparisons such as `2006' against `20060101', erroneously
     producing a false result.  (Bug#21475
     (http://bugs.mysql.com/21475))

   * For row-based replication, log rotation could occur at an improper
     time.  (Bug#21474 (http://bugs.mysql.com/21474))

   * `myisam_ftdump' produced bad counts for common words.  (Bug#21459
     (http://bugs.mysql.com/21459))

   * Adding `ORDER BY' to a `SELECT DISTINCT(EXPR)' query could produce
     incorrect results.  (Bug#21456 (http://bugs.mysql.com/21456))

   * The URL into the online manual that is printed in the stack trace
     message by the server was out of date.  (Bug#21449
     (http://bugs.mysql.com/21449))

   * Database and table names have a maximum length of 64 characters
     (even if they contain multi-byte characters), but were truncated
     to 64 bytes.

     *Note*:

     An additional fix was made in MySQL 5.1.18.

     (Bug#21432 (http://bugs.mysql.com/21432))

   * With `max_sp_recursion' set to 0, a stored procedure that executed
     a `SHOW CREATE PROCEDURE' statement for itself triggered a
     recursion limit exceeded error, though the statement involves no
     recursion.  (Bug#21416 (http://bugs.mysql.com/21416))

   * After `FLUSH TABLES WITH READ LOCK' followed by `UNLOCK TABLES',
     attempts to drop or alter a stored routine failed with an error
     that the routine did not exist, and attempts to execute the
     routine failed with a lock conflict error.  (Bug#21414
     (http://bugs.mysql.com/21414))

   * On 64-bit Windows, a missing table generated error 1017, not the
     correct value of 1146.  (Bug#21396 (http://bugs.mysql.com/21396))

   * Table aliases in multiple-table `DELETE' statements sometimes were
     not resolved.  (Bug#21392 (http://bugs.mysql.com/21392))

   * The optimizer sometimes produced an incorrect row-count estimate
     after elimination of `const' tables. This resulted in choosing
     extremely inefficient execution plans in same cases when
     distribution of data in joins were skewed.  (Bug#21390
     (http://bugs.mysql.com/21390))

   * For multiple-table `UPDATE' statements, storage engines were not
     notified of duplicate-key errors.  (Bug#21381
     (http://bugs.mysql.com/21381))

   * Using relative paths for `DATA DIRECTORY' or `INDEX DIRECTORY'
     with a partitioned table generated a warning rather than an error,
     and caused `junk' files to be created in the server's data
     directory.  (Bug#21350 (http://bugs.mysql.com/21350))

   * Using `EXPLAIN PARTITIONS' with a query on a table whose
     partitioning expression was based on the value of a `DATE' column
     could sometimes cause the server to crash.  (Bug#21339
     (http://bugs.mysql.com/21339))

   * The feature of being able to recover a temporary table named
     `#sql_ID' in `InnoDB' by creating a table named
     `rsql_ID_recover_innodb_tmp_table' was broken by the introduction
     of the new identifier encoding in MySQL 5.1.6 (Bug#21313
     (http://bugs.mysql.com/21313))

   * It was possible for a stored routine with a non-`latin1' name to
     cause a stack overrun.  (Bug#21311 (http://bugs.mysql.com/21311))

   * A query result could be sorted improperly when using `ORDER BY'
     for the second table in a join.  (Bug#21302
     (http://bugs.mysql.com/21302))

   * Query results could be incorrect if the `WHERE' clause contained
     `t.KEY_PART NOT IN (VAL_LIST)', where VAL_LIST is a list of more
     than 1000 constants.  (Bug#21282 (http://bugs.mysql.com/21282))

   * Queries that used the `index_merge' and `sort_union' methods to
     access an `InnoDB' table could produce inaccurate results. This
     issue was introduced in MySQL 5.1.10 when a new handler and bitmap
     interface was implemented.  (Bug#21277
     (http://bugs.mysql.com/21277))

   * For user-defined functions created with `CREATE FUNCTION', the
     `DEFINER' clause is not legal, but no error was generated.
     (Bug#21269 (http://bugs.mysql.com/21269))

   * The `SELECT' privilege was required for an insert on a view,
     instead of the `INSERT' privilege.  (Bug#21261
     (http://bugs.mysql.com/21261)) This regression was introduced by
     Bug#20989 (http://bugs.mysql.com/20989)

   * `mysql_config --libmysqld-libs' did not produce any SSL options
     necessary for linking `libmysqld' with SSL support enabled.
     (Bug#21239 (http://bugs.mysql.com/21239))

   * Subqueries on `INFORMATION_SCHEMA' tables could erroneously return
     an empty result.  (Bug#21231 (http://bugs.mysql.com/21231))

   * `mysql_upgrade' created temporary files in a possibly insecure way.
     (Bug#21224 (http://bugs.mysql.com/21224))

   * When `DROP DATABASE' or `SHOW OPEN TABLES' was issued while
     concurrently in another connection issuing `DROP TABLE', `RENAME
     TABLE', `CREATE TABLE LIKE' or any other statement that required a
     name lock, the server crashed.  (Bug#21216
     (http://bugs.mysql.com/21216), Bug#19403
     (http://bugs.mysql.com/19403))

   * The `--master-data' option for `mysqldump' requires certain
     privileges, but `mysqldump' generated a truncated dump file
     without producing an appropriate error message or exit status if
     the invoking user did not have those privileges.  (Bug#21215
     (http://bugs.mysql.com/21215))

   * Using `ALTER TABLE ... REORGANIZE PARTITIONS' to reduce the number
     of subpartitions to 1 caused the server to crash.  (Bug#21210
     (http://bugs.mysql.com/21210))

   * In the package of pre-built time zone tables that is available for
     download at `timezones.html', the tables now explicitly use the
     `utf8' character set so that they work the same way regardless of
     the system character set value.  (Bug#21208
     (http://bugs.mysql.com/21208))

   * Under heavy load (executing more than 1024 simultaneous complex
     queries), a problem in the code that handles internal temporary
     tables could lead to writing beyond allocated space and memory
     corruption.

     Use of more than 1024 simultaneous cursors server wide also could
     lead to memory corruption. This applies to both stored procedure
     cursors and C API cursors.  (Bug#21206
     (http://bugs.mysql.com/21206))

   * When run with the `--use-threads' option, `mysqlimport' returned a
     random exit code.  (Bug#21188 (http://bugs.mysql.com/21188))

   * A subquery that uses an index for both the `WHERE' and `ORDER BY'
     clauses produced an empty result.  (Bug#21180
     (http://bugs.mysql.com/21180))

   * Running `SHOW TABLE STATUS' on any `InnoDB' table having at least
     one record could crash the server. Note that this was not due to
     any issue in the `InnoDB' storage engine, but rather with
     `AUTO_INCREMENT' handling in the partitioning code -- however, the
     table did not have to have an `AUTO_INCREMENT' column for the bug
     to manifest.  (Bug#21173 (http://bugs.mysql.com/21173))

   * Some prepared statements caused a server crash when executed a
     second time.  (Bug#21166 (http://bugs.mysql.com/21166))

   * The optimizer assumed that if `(a=x AND b=x)' is true, `(a=x AND
     b=x) AND a=b' is also true.  But that is not always so if `a' and
     `b' have different data types.  (Bug#21159
     (http://bugs.mysql.com/21159))

   * Some `ALTER TABLE' statements affecting a table's subpartitioning
     could hang.  (Bug#21143 (http://bugs.mysql.com/21143))

   * Certain malformed `INSERT' statements could crash the `mysql'
     client.  (Bug#21142 (http://bugs.mysql.com/21142))

   * `SHOW INNODB STATUS' contained some duplicate output.  (Bug#21113
     (http://bugs.mysql.com/21113))

   * `InnoDB' was slow with more than 100,000 `.idb' files.  (Bug#21112
     (http://bugs.mysql.com/21112))

   * Creating a `TEMPORARY' table with the same name as an existing
     table that was locked by another client could result in a lock
     conflict for `DROP TEMPORARY TABLE' because the server
     unnecessarily tried to acquire a name lock.  (Bug#21096
     (http://bugs.mysql.com/21096))

   * Performing an `INSERT' on a view that was defined using a `SELECT'
     that specified a collation and a column alias caused the server to
     crash .  (Bug#21086 (http://bugs.mysql.com/21086))

   * Incorrect results could be obtained from re-execution of a
     parametrized prepared statement or a stored routine with a
     `SELECT' that uses `LEFT JOIN' with a second table having only one
     row.  (Bug#21081 (http://bugs.mysql.com/21081))

   * `ALTER VIEW' did not retain existing values of attributes that had
     been originally specified but were not changed in the `ALTER VIEW'
     statement.  (Bug#21080 (http://bugs.mysql.com/21080))

   * The `myisam_stats_method' variable was mishandled when set from an
     option file or on the command line.  (Bug#21054
     (http://bugs.mysql.com/21054))

   * With `query_cache_type' set to 0, `RESET QUERY CACHE' was very
     slow and other threads were blocked during the operation. Now a
     cache reset is faster and non-blocking.  (Bug#21051
     (http://bugs.mysql.com/21051))

   * `mysql' crashed for very long arguments to the `connect' command.
     (Bug#21042 (http://bugs.mysql.com/21042))

   * When creating a table using `CREATE...SELECT' and a stored
     procedure, there would be a mismatch between the binary log and
     transaction cache which would cause a server crash.  (Bug#21039
     (http://bugs.mysql.com/21039))

   * A query using `WHERE COLUMN = CONSTANT OR COLUMN IS NULL' did not
     return consistent results on successive invocations. The COLUMN in
     each part of the `WHERE' clause could be either the same column,
     or two different columns, for the effect to be observed.
     (Bug#21019 (http://bugs.mysql.com/21019))

   * `mysqldump' sometimes did not select the correct database before
     trying to dump views from it, resulting in an empty result set
     that caused `mysqldump' to die with a segmentation fault.
     (Bug#21014 (http://bugs.mysql.com/21014))

   * Performance during an import on a table with a trigger that called
     a stored procedure was severely degraded.  (Bug#21013
     (http://bugs.mysql.com/21013))

   * `mysql_upgrade' produced a malformed `upgrade_defaults' file by
     overwriting the `[client]' group header with a `password' option.
     This prevented `mysqlcheck' from running successfully when invoked
     by `mysql_upgrade'.  (Bug#21011 (http://bugs.mysql.com/21011))

   * A query of the form shown here caused the server to crash:

          SELECT * FROM t1 NATURAL JOIN (
              t2 JOIN (
                  t3 NATURAL JOIN t4,
                  t5 NATURAL JOIN t6
              )
              ON (t3.id3 = t2.id3 AND t5.id5 = t2.id5)
          );

     (Bug#21007 (http://bugs.mysql.com/21007))

   * A `SELECT' that used a subquery in the `FROM' clause that did not
     select from a table failed when the subquery was used in a join.
     (Bug#21002 (http://bugs.mysql.com/21002))

   * `REPLACE ... SELECT' for a view required the `INSERT' privilege
     for tables other than the table being modified.  (Bug#20989
     (http://bugs.mysql.com/20989))

   * `STR_TO_DATE()' sometimes would return `NULL' if the `%D' format
     specifier was not the last specifier in the format string.
     (Bug#20987 (http://bugs.mysql.com/20987))

   * A query using `WHERE NOT (COLUMN < ANY (SUBQUERY))' yielded a
     different result from the same query using the same COLUMN and
     SUBQUERY with `WHERE (COLUMN > ANY (SUBQUERY))'.  (Bug#20975
     (http://bugs.mysql.com/20975))

   * Under certain circumstances, `AVG(KEY_VAL)' returned a value but
     `MAX(KEY_VAL)' returned an empty set due to incorrect application
     of `MIN()/MAX()' optimization.  (Bug#20954
     (http://bugs.mysql.com/20954))

   * In mixed-format binary logging mode, stored functions, triggers,
     and views that use functions in their body that require row-based
     logging did not replicate reliably because the logging did not
     switch from statement-based to row-based format. For example,
     `INSERT INTO t SELECT FROM v', where `v' is a view that selects
     `UUID()' could cause problems.  This limitation has been removed.
     (Bug#20930 (http://bugs.mysql.com/20930))

   * Closing of temporary tables failed if binary logging was not
     enabled.  (Bug#20919 (http://bugs.mysql.com/20919))

   * Use of zero-length variable names caused a server crash.
     (Bug#20908 (http://bugs.mysql.com/20908))

   * Building `mysql' on Windows with CMake 2.4 would fail to create
     `libmysqld' correctly.  (Bug#20907 (http://bugs.mysql.com/20907))

   * Creating a partitioned table that used the `InnoDB' storage engine
     and then restarting `mysqld' with `--skip-innodb' caused MySQL to
     crash.  (Bug#20871 (http://bugs.mysql.com/20871))

   * For certain queries, the server incorrectly resolved a reference
     to an aggregate function and crashed.  (Bug#20868
     (http://bugs.mysql.com/20868))

   * If the binary logging format was changed between the times when a
     locked table was modified and when it was unlocked, the binary log
     contents were incorrect.  (Bug#20863 (http://bugs.mysql.com/20863))

   * It was possible to provide the `ExtractValue()' function with
     input containing `tags' that were not valid XML; for example, it
     was possible to use tag names beginning with a digit, which are
     disallowed by the W3C's XML 1.0 specification. Such cases caused
     the function to return `junk' output rather than an error message
     signalling the user as to the true nature of the problem.
     (Bug#20854 (http://bugs.mysql.com/20854))

   * `InnoDB' (Partitioning): Updating an `InnoDB' table using `HASH'
     partitioning with a composite primary key would cause the server
     to hang.  (Bug#20852 (http://bugs.mysql.com/20852))

   * A race condition during slave server shutdown caused an assert
     failure.  (Bug#20850 (http://bugs.mysql.com/20850))

   * `mysqldump' did not add version-specific comments around `WITH
     PARSER' and `TABLESPACE ... STORAGE DISK' clauses for `CREATE
     TABLE' statements, causing dump files from servers where these
     features were in use to fail when loaded into older servers.
     (Bug#20841 (http://bugs.mysql.com/20841))

   * For multiple `INSERT DELAYED' statements executed in a batch by
     the delayed-insert handler thread, not all rows were written to
     the binary log.  (Bug#20821 (http://bugs.mysql.com/20821))

   * The `ExtractValue()' function did not accept XML tag names
     containing a period (`.') character.  (Bug#20795
     (http://bugs.mysql.com/20795))

   * Using aggregate functions in subqueries yielded incorrect results
     under certain circumstances due to incorrect application of
     `MIN()'/`MAX()' optimization.  (Bug#20792
     (http://bugs.mysql.com/20792))

   * On Windows, inserting into a `MERGE' table after renaming an
     underlying `MyISAM' table caused a server crash.  (Bug#20789
     (http://bugs.mysql.com/20789))

   * Within stored routines, some error messages were printed
     incorrectly. A non-null-terminated string was passed to a
     message-printing routine that expected a null-terminated string.
     (Bug#20778 (http://bugs.mysql.com/20778))

   * Merging multiple partitions having subpartitions into a single
     partition with subpartitions, or splitting a single partition
     having subpartitions into multiple partitions with subpartitions,
     could sometimes crash the server. These issues were associated
     with a failure reported in the `partition_range' test.  (Bug#20767
     (http://bugs.mysql.com/20767), Bug#20893
     (http://bugs.mysql.com/20893), Bug#20766
     (http://bugs.mysql.com/20766), Bug#21357
     (http://bugs.mysql.com/21357))

   * Searches against a `ZEROFILL' column of a partitioned table could
     fail when the `ZEROFILL' column was part of the table's
     partitioning key.  (Bug#20733 (http://bugs.mysql.com/20733))

   * If a column definition contained a character set declaration, but
     a `DEFAULT' value began with an introducer, the introducer
     character set was used as the column character set.  (Bug#20695
     (http://bugs.mysql.com/20695))

   * An `UPDATE' that referred to a key column in the `WHERE' clause
     and activated a trigger that modified the column resulted in a
     loop.  (Bug#20670 (http://bugs.mysql.com/20670))

   * Issuing a `SHOW CREATE FUNCTION' or `SHOW CREATE PROCEDURE'
     statement without sufficient privileges could crash the `mysql'
     client.  (Bug#20664 (http://bugs.mysql.com/20664))

   * With mixed-format binary logging, `INSERT DELAYED' statements were
     logged using statement-based logging, and they did not replicate
     properly for statements that used values such as `UUID()',
     `RAND()', or user-defined variables that require row-based
     logging. To correct this, the `DELAYED' handler thread how
     switches to row-based logging if the logging format is mixed.
     (Bug#20633 (http://bugs.mysql.com/20633), Bug#20649
     (http://bugs.mysql.com/20649))

   * `INSERT DELAYED' did not honor `SET INSERT_ID' or the
     `auto_increment_*' system variables.  (Bug#20627
     (http://bugs.mysql.com/20627), Bug#20830
     (http://bugs.mysql.com/20830))

   * A buffer overwrite error in Instance Manager caused a crash.
     (Bug#20622 (http://bugs.mysql.com/20622))

   * Loading a plugin caused any an existing plugin with the same name
     to be lost.  (Bug#20615 (http://bugs.mysql.com/20615))

   * A query selecting records from a single partition of a partitioned
     table and using `ORDER BY IC DESC' (where IC represents an indexed
     column) could cause errors or crash the server.  (Bug#20583
     (http://bugs.mysql.com/20583))

   * If the `auto_increment_offset' setting causes MySQL to generate a
     value larger than the column's maximum possible value, the
     `INSERT' statement is accepted in strict SQL mode, whereas but
     should fail with an error.  (Bug#20573
     (http://bugs.mysql.com/20573))

   * In a view defined with `SQL SECURITY DEFINER', the
     `CURRENT_USER()' function returned the invoker, not the definer.
     (Bug#20570 (http://bugs.mysql.com/20570))

   * The `fill_help_tables.sql' file did not contain a `SET NAMES
     'utf8'' statement to indicate its encoding. This caused problems
     for some settings of the MySQL character set such as `big5'.
     (Bug#20551 (http://bugs.mysql.com/20551))

   * Scheduled events that invoked stored procedures executing DDL
     operations on partitioned tables could crash the server.
     (Bug#20548 (http://bugs.mysql.com/20548))

   * Users who had the `SHOW VIEW' privilege for a view and privileges
     on one of the view's base tables could not see records in
     `INFORMATION_SCHEMA' tables relating to the base table.
     (Bug#20543 (http://bugs.mysql.com/20543))

   * The `fill_help_tables.sql' file did not load properly if the
     `ANSI_QUOTES' SQL mode was enabled.  (Bug#20542
     (http://bugs.mysql.com/20542))

   * The `MD5()', `SHA1()', and `ENCRYPT()' functions should return a
     binary string, but the result sometimes was converted to the
     character set of the argument.  `MAKE_SET()' and `EXPORT_SET()'
     now use the correct character set for their default separators,
     resulting in consistent result strings which can be coerced
     according to normal character set rules.  (Bug#20536
     (http://bugs.mysql.com/20536))

   * With the `auto_increment_increment' system variable set larger
     than 1, if the next generated `AUTO_INCREMENT' value would be
     larger than the column's maximum value, the value would be clipped
     down to that maximum value and inserted, even if the resulting
     value would not be in the generated sequence. This could cause
     problems for master-master replication. Now the server clips the
     value down to the previous value in the sequence, which correctly
     produces a duplicate-key error if that value already exists in the
     column.  (Bug#20524 (http://bugs.mysql.com/20524))

   * In mixed binary logging mode, a temporary switch from
     statement-based logging to row-based logging occurs when storing a
     row that uses a function such as `UUID()' into a temporary table.
     However, temporary table changes are not written to the binary log
     under row-based logging, so the row does not exist on the slave. A
     subsequent select from the temporary table to a non-temporary
     table using statement-based logging works correctly on the master,
     but not on the slave where the row does not exist. Replication no
     longer switches back from row-based logging to statement-based
     logging until there are no temporary tables for the session.
     (Bug#20499 (http://bugs.mysql.com/20499))

   * If a partitioned `InnoDB' table contained an `AUTO_INCREMENT'
     column, a `SHOW' statement could cause an assertion failure with
     more than one connection.  (Bug#20493
     (http://bugs.mysql.com/20493))

   * Using `EXPLAIN PARTITIONS' with a `UNION' query could crash the
     server. This could occur whether or not the query actually used any
     partitioned tables.  (Bug#20484 (http://bugs.mysql.com/20484))

   * Creation of a view as a join of views or tables could fail if the
     views or tables are in different databases.  (Bug#20482
     (http://bugs.mysql.com/20482))

   * `SELECT' statements using `GROUP BY' against a view could have
     missing columns in the output when there was a trigger defined on
     one of the base tables for the view.  (Bug#20466
     (http://bugs.mysql.com/20466))

   * `CREATE PROCEDURE', `CREATE FUNTION', `CREATE TRIGGER', and
     `CREATE VIEW' statements containing multi-line comments (`/* ...
     */') could not be replicated.  (Bug#20438
     (http://bugs.mysql.com/20438))

   * For connections that required a `SUBJECT' value, a check was
     performed to verify that the value was correct, but the connection
     was not refused if not.  (Bug#20411 (http://bugs.mysql.com/20411))

   * `mysql_upgrade' was missing from binary MySQL distributions.
     (Bug#20403 (http://bugs.mysql.com/20403), Bug#18516
     (http://bugs.mysql.com/18516), Bug#20556
     (http://bugs.mysql.com/20556))

   * Some user-level errors were being written to the server's error
     log, which is for server errors.  (Bug#20402
     (http://bugs.mysql.com/20402))

   * Using `ALTER TABLE ... ENGINE = X', where X was not a storage
     engine supported by the server, would cause `mysqld' to crash.
     (Bug#20397 (http://bugs.mysql.com/20397))

   * User names have a maximum length of 16 characters (even if they
     contain multi-byte characters), but were being truncated to 16
     bytes.  (Bug#20393 (http://bugs.mysql.com/20393))

   * Some queries using `ORDER BY ... DESC' on subpartitioned tables
     could crash the server.  (Bug#20389 (http://bugs.mysql.com/20389))

   * `mysqlslap' did not enable the `CLIENT_MULTI_RESULTS' flag when
     connecting, which is necessary for executing stored procedures.
     (Bug#20365 (http://bugs.mysql.com/20365))

   * Queries using an indexed column as the argument for the `MIN()' and
     `MAX()' functions following an `ALTER TABLE .. DISABLE KEYS'
     statement returned `Got error 124 from storage engine' until
     `ALTER TABLE ... ENABLE KEYS' was run on the table.  (Bug#20357
     (http://bugs.mysql.com/20357))

   * When a statement used a stored function that inserted into an
     `AUTO_INCREMENT' column, the generated `AUTO_INCREMENT' value was
     not written into the binary log, so a different value could in
     some cases be inserted on the slave.  (Bug#20341
     (http://bugs.mysql.com/20341))

   * Partitions were represented internally as the wrong data type,
     which led in some cases to failures of queries such as `SELECT
     COUNT(*) FROM INFORMATION_SCHEMA.PARTITIONS WHERE PARTITION_NAME =
     'PARTITION_NAME''.  (Bug#20340 (http://bugs.mysql.com/20340))

   * A stored procedure that used `LAST_INSERT_ID()' did not replicate
     properly using statement-based binary logging.  (Bug#20339
     (http://bugs.mysql.com/20339))

   * `PROCEDURE ANALYSE()' returned incorrect values of M `FLOAT(M, D)'
     and `DOUBLE(M, D)'.  (Bug#20305 (http://bugs.mysql.com/20305))

   * Defining a table partitioned by `LIST' with a single `PARTITION
     ... VALUES IN (NULL)' clause could lead to server crashes,
     particularly with queries having `WHERE' conditions comparing the
     partitioning key with a constant.  (Bug#20268
     (http://bugs.mysql.com/20268), Bug#19801
     (http://bugs.mysql.com/19801))

   * When using row based replication, a `CREATE TABLE...SELECT'
     statement would be replicated, even if the table creation failed
     on the master (for example, due to a duplicate key failure).
     (Bug#20265 (http://bugs.mysql.com/20265))

   * Partition pruning could cause incorrect results from queries, such
     missing rows, when the partitioning expression relied on a `BIGINT
     UNSIGNED' column.  (Bug#20257 (http://bugs.mysql.com/20257))

   * For a `MyISAM' table locked with `LOCK TABLES ...WRITE', queries
     optimized using the `index_merge' method did not show rows inserted
     with the lock in place.  (Bug#20256 (http://bugs.mysql.com/20256))

   * `mysqldump' produced a malformed dump file when dumping multiple
     databases that contained views.  (Bug#20221
     (http://bugs.mysql.com/20221))

   * Running `InnoDB' with many concurrent threads could cause memory
     corruption and a seg fault due to a bug introduced in MySQL 5.1.11.
     (Bug#20213 (http://bugs.mysql.com/20213))

   * `SUBSTRING()' results sometimes were stored improperly into a
     temporary table when multi-byte character sets were used.
     (Bug#20204 (http://bugs.mysql.com/20204))

   * The thread for `INSERT DELAYED' rows was maintaining a separate
     `AUTO_INCREMENT' counter, resulting in incorrect values being
     assigned if `DELAYED' and non-`DELAYED' inserts were mixed.
     (Bug#20195 (http://bugs.mysql.com/20195))

   * If a table on a slave server had a higher `AUTO_INCREMENT' counter
     than the corresponding master table (even though all rows of the
     two tables were identical), in some cases `REPLACE' or `INSERT ...
     ON DUPLICATE KEY UPDATE' would not replicate properly using
     statement-based logging. (Different values would be inserted on
     the master and slave.)  (Bug#20188 (http://bugs.mysql.com/20188))

   * The `--default-storage-engine' server option did not work.
     (Bug#20168 (http://bugs.mysql.com/20168))

   * For a table having `LINEAR HASH' subpartitions, the `LINEAR'
     keyword did not appear in the `SUBPARTITION_METHOD' column of the
     `INFORMATION_SCHEMA.PARTITIONS' table.  (Bug#20161
     (http://bugs.mysql.com/20161))

   * For a `DATE' parameter sent via a `MYSQL_TIME' data structure,
     *Note `mysql_stmt_execute()': mysql-stmt-execute.  zeroed the
     hour, minute, and second members of the structure rather than
     treating them as read-only.  (Bug#20152
     (http://bugs.mysql.com/20152))

   * `perror' crashed on Solaris due to `NULL' return value of
     `strerror()' system call.  (Bug#20145
     (http://bugs.mysql.com/20145))

   * `FLUSH TABLES' followed by a `LOCK TABLES' statement to lock a log
     table and a non-log table caused an infinite loop and high CPU
     use. Now `FLUSH TABLES' ignores log tables. To flush the log
     tables, use `FLUSH LOGS' instead.  (Bug#20139
     (http://bugs.mysql.com/20139))

   * On Linux, `libmysqlclient' when compiled with yaSSL using the
     `icc' compiler had a spurious dependency on C++ libraries.
     (Bug#20119 (http://bugs.mysql.com/20119))

   * For an `ENUM' column that used the `ucs2' character set, using
     `ALTER TABLE' to modify the column definition caused the default
     value to be lost.  (Bug#20108 (http://bugs.mysql.com/20108))

   * For `mysql', escaping with backslash sometimes did not work.
     (Bug#20103 (http://bugs.mysql.com/20103))

   * Queries on tables that were partitioned by `KEY' and had a
     `VARCHAR' column as the partitioning key produced an empty result
     set.  (Bug#20086 (http://bugs.mysql.com/20086))

   * A number of dependency issues in the RPM `bench' and `test'
     packages caused installation of these packages to fail.
     (Bug#20078 (http://bugs.mysql.com/20078))

   * Use of `MIN()' or `MAX()' with `GROUP BY' on a `ucs2' column could
     cause a server crash.  (Bug#20076 (http://bugs.mysql.com/20076))

   * `mysqld --flush' failed to flush `MyISAM' table changes to disk
     following an `UPDATE' statement for which no updated column had an
     index.  (Bug#20060 (http://bugs.mysql.com/20060))

   * In MySQL 5.1.11, the `--with-openssl' and `--with-yassl' options
     were replaced by `--with-ssl'. But no message was issued if the
     old options were given. Now `configure' produces a message
     indicating that the new option should be used and exits.
     (Bug#20002 (http://bugs.mysql.com/20002))

   * When a statement is executed that does not generate any rows, an
     extra table map event and associated binrows event would be
     generated and written to the binary log.  (Bug#19995
     (http://bugs.mysql.com/19995))

   * Join conditions using index prefixes on `utf8' columns of `InnoDB'
     tables incorrectly ignored rows where the length of the actual
     value was greater than the length of the index prefix.  (Bug#19960
     (http://bugs.mysql.com/19960))

   * `AUTHORS' and `CONTRIBUTORS' were not treated as reserved words.
     (Bug#19939 (http://bugs.mysql.com/19939))

   * The `query' command for `mysqltest' did not work.  (Bug#19890
     (http://bugs.mysql.com/19890))

   * Shutting down a slave in a replication scenario where temporary
     tables are in use would cause the slave to produce a core dump.
     (Bug#19881 (http://bugs.mysql.com/19881))

   * Identifiers with embedded escape characters were not handled
     correctly by some `SHOW' statements due to some old code that was
     doing some extra unescaping.  (Bug#19874
     (http://bugs.mysql.com/19874))

   * When executing a `SELECT' with `ORDER BY' on a view that is
     constructed from a `SELECT' statement containing a stored
     function, the stored function was evaluated too many times.
     (Bug#19862 (http://bugs.mysql.com/19862))

   * Using `SELECT' on a corrupt `MyISAM' table using the dynamic
     record format could cause a server crash.  (Bug#19835
     (http://bugs.mysql.com/19835))

   * Using cursors with `READ COMMITTED' isolation level could cause
     `InnoDB' to crash.  (Bug#19834 (http://bugs.mysql.com/19834))

   * `CREATE DATABASE', `RENAME DATABASE', and `DROP DATABASE' could
     deadlock in cases where there was a global read lock.  (Bug#19815
     (http://bugs.mysql.com/19815))

   * The yaSSL library bundled with `libmysqlclient' had some conflicts
     with OpenSSL. Now macros are used to rename the conflicting
     symbols to have a prefix of `ya'.  (Bug#19810
     (http://bugs.mysql.com/19810))

   * The `WITH CHECK OPTION' was not enforced when a `REPLACE'
     statement was executed against a view.  (Bug#19789
     (http://bugs.mysql.com/19789))

   * Multiple-table updates with `FEDERATED' tables could cause a
     server crash.  (Bug#19773 (http://bugs.mysql.com/19773))

   * On 64-bit systems, use of the `cp1250' character set with a
     primary key column in a `LIKE' clause caused a server crash for
     patterns having letters in the range 128..255.  (Bug#19741
     (http://bugs.mysql.com/19741))

   * `make install' tried to build files that should already have been
     built by `make all', causing a failure if installation was
     performed using a different account than the one used for the
     initial build.  (Bug#19738 (http://bugs.mysql.com/19738))

   * `InnoDB' unlocked its data directory before committing a
     transaction, potentially resulting in non-recoverable tables if a
     server crash occurred before the commit.  (Bug#19727
     (http://bugs.mysql.com/19727))

   * An issue with yaSSL prevented Connector/J clients from connecting
     to the server using a certificate.  (Bug#19705
     (http://bugs.mysql.com/19705))

   * For a `MyISAM' table with a `FULLTEXT' index, compression with
     `myisampack' or a check with `myisamchk' after compression
     resulted in table corruption.  (Bug#19702
     (http://bugs.mysql.com/19702))

   * The `EGNINE' clause was displayed in the output of `SHOW CREATE
     TABLE' for partitioned tables when the SQL mode included
     `no_table_options'.  (Bug#19695 (http://bugs.mysql.com/19695))

   * A cast problem caused incorrect results for prepared statements
     that returned float values when MySQL was compiled with `gcc' 4.0.
     (Bug#19694 (http://bugs.mysql.com/19694))

   * `EXPLAIN PARTITIONS' would produce illegible output in the
     `partitions' column if the length of text to be displayed in that
     column was too long. This could occur when very many partitions
     were defined for the table, partitions were given very long names,
     or due to a combination of the two.  (Bug#19684
     (http://bugs.mysql.com/19684))

   * The *Note `mysql_list_fields()': mysql-list-fields. C API function
     returned the incorrect table name for views.  (Bug#19671
     (http://bugs.mysql.com/19671))

   * If a query had a condition of the form ` TABLEX.KEY = TABLEY.KEY
     ', which participated in equality propagation and also was used
     for `ref' access, then early `ref'-access `NULL' filtering was not
     peformed for the condition. This could make query execution slower.
     (Bug#19649 (http://bugs.mysql.com/19649))

   * Re-execution of a prepared multiple-table `DELETE' statement that
     involves a trigger or stored function can result in a server crash.
     (Bug#19634 (http://bugs.mysql.com/19634))

   * The effect of a stored function or trigger that caused
     `AUTO_INCREMENT' values to be generated for multiple tables was
     not logged properly if statement-based logging was used. Only the
     first table's value was logged, causing replication to fail. Under
     mixed logging format, this is dealt with by switching to row-based
     logging for the function or trigger. For statement-based logging,
     this remains a problem.  (Bug#19630 (http://bugs.mysql.com/19630))

   * File size specifications for `InnoDB' data files were case
     sensitive.  (Bug#19609 (http://bugs.mysql.com/19609))

   * `CHECK TABLE' on a `MyISAM' table briefly cleared its
     `AUTO_INCREMENT' value, while holding only a read lock. Concurrent
     inserts to that table could use the wrong `AUTO_INCREMENT' value.
     `CHECK TABLE' no longer modifies the `AUTO_INCREMENT' value.
     (Bug#19604 (http://bugs.mysql.com/19604))

   * Some yaSSL public function names conflicted with those from
     OpenSSL, causing conflicts for applications that linked against
     both OpenSSL and a version of `libmysqlclient' that was built with
     yaSSL support. The yaSSL public functions now are renamed to avoid
     this conflict.  (Bug#19575 (http://bugs.mysql.com/19575))

   * In the `INFORMATION_SCHEMA.FILES' table, the `INITIAL_SIZE',
     `MAXIMUM_SIZE', and `AUTOEXTEND_SIZE' columns incorrectly were
     being stored as `VARCHAR' rather than `BIGINT'. .  (Bug#19544
     (http://bugs.mysql.com/19544))

   * `InnoDB' failed to increment the `handler_read_prev' counter.
     (Bug#19542 (http://bugs.mysql.com/19542))

   * Portions of statements related to partitioning were not surrounded
     by version-specific comments by `mysqldump', breaking backward
     compatibility for dump files.  (Bug#19488
     (http://bugs.mysql.com/19488))

   * For row-based replication, the `BINLOG' statement did not lock
     tables properly, causing a crash for some table types.  (Bug#19459
     (http://bugs.mysql.com/19459))

   * Column names supplied for a view created on a master server could
     be lost on a slave server.  (Bug#19419
     (http://bugs.mysql.com/19419))

   * Repeated `DROP TABLE' statements in a stored procedure could
     sometimes cause the server to crash.  (Bug#19399
     (http://bugs.mysql.com/19399))

   * Renaming a database to itself caused a server crash.  (Bug#19392
     (http://bugs.mysql.com/19392))

   * Race conditions on certain platforms could cause the Instance
     Manager to fail to initialize.  (Bug#19391
     (http://bugs.mysql.com/19391))

   * When not running in strict mode, the server failed to convert the
     invalid years portion of a `DATE' or `DATETIME' value to `'0000''
     when inserting it into a table.

     *Note*:

     This fix was reverted in MySQL 5.1.18.

     (Bug#19370 (http://bugs.mysql.com/19370)) See also Bug#25301
     (http://bugs.mysql.com/25301)

   * Use of the `--no-pager' option caused `mysql' to crash.
     (Bug#19363 (http://bugs.mysql.com/19363))

   * Multiple calls to a stored procedure that altered a partitioned
     `MyISAM' table would cause the server to crash.  (Bug#19309
     (http://bugs.mysql.com/19309))

   * `ALTER TABLE ... COALESCE PARTITION' did not delete the files
     associated with the partitions that were removed.  (Bug#19305
     (http://bugs.mysql.com/19305))

   * Adding an index to a partitioned table that had been created using
     `AUTO_INCREMENT = VALUE ' caused the `AUTO_INCREMENT' value to be
     reset.  (Bug#19281 (http://bugs.mysql.com/19281))

   * Multiple-table `DELETE' statements containing a subquery that
     selected from one of the tables being modified caused a server
     crash.  (Bug#19225 (http://bugs.mysql.com/19225))

   * The final parenthesis of a `CREATE INDEX' statement occurring in a
     stored procedure was omitted from the binary log when the stored
     procedure was called.  (Bug#19207 (http://bugs.mysql.com/19207))

   * An `ALTER TABLE' operation that does not need to copy data, when
     executed on a table created prior to MySQL 4.0.25, could result in
     a server crash for subsequent accesses to the table.  (Bug#19192
     (http://bugs.mysql.com/19192))

   * SSL connections using yaSSL on OpenBSD could fail.  (Bug#19191
     (http://bugs.mysql.com/19191))

   * The dropping of a temporary table whose name contained a backtick
     ('``'') character was not correctly written to the binary log,
     which also caused it not to be replicated correctly.  (Bug#19188
     (http://bugs.mysql.com/19188))

   * `ALTER TABLE ... REBUILD PARTITION' could cause the server to hang
     or crash.  (Bug#19122 (http://bugs.mysql.com/19122))

   * With row-based replication, replicating a statement to a slave
     where the table had additional columns relative to the master
     table did not work.  (Bug#19069 (http://bugs.mysql.com/19069))

   * Using `ALTER TABLE' on a subpartitioned table caused the server to
     crash.  (Bug#19067 (http://bugs.mysql.com/19067))

   * Trying to execute a query having a `WHERE' clause using `INT_COL =
     "STRING_VALUE" OR INT_COL IS NULL' on a partitioned table whose
     partitioning or subpartitioning function used the integer column
     INT_COL would crash the server.  (Bug#19055
     (http://bugs.mysql.com/19055))

   * Valgrind revealed several issues with `mysqld' that were
     corrected: A dangling stack pointer being overwritten; possible
     uninitialized data in a string comparison; memory corruption in
     replication slaves when switching databases; `syscall()' write
     parameter pointing to an uninitialized byte.  (Bug#19022
     (http://bugs.mysql.com/19022), Bug#20579
     (http://bugs.mysql.com/20579), Bug#20769
     (http://bugs.mysql.com/20769), Bug#20783
     (http://bugs.mysql.com/20783), Bug#20791
     (http://bugs.mysql.com/20791))

   * A redundant table map event could be generated in the binary log
     when there were no actual changes to a table being replicated.  In
     addition, a slave failed to stop when attempting to replicate a
     table that did not exist on the slave.  (Bug#18948
     (http://bugs.mysql.com/18948))

   * A `SELECT' with a subquery that was bound to the outer query over
     multiple columns returned different results when a constant was
     used instead of one of the dependant columns.  (Bug#18925
     (http://bugs.mysql.com/18925))

   * It was possible using `ALTER EVENT ... RENAME ...' to move an
     event to a database on which the user did not have the `EVENT'
     privilege.  (Bug#18897 (http://bugs.mysql.com/18897))

   * When used in the `DO' clause of a `CREATE EVENT' statement, the
     statements `CREATE EVENT', `CREATE FUNCTION', and `CREATE
     PROCEDURE' caused the server to crash. (These statements are not
     permitted inside `CREATE EVENT'.)  (Bug#18896
     (http://bugs.mysql.com/18896), Bug#16409
     (http://bugs.mysql.com/16409))

   * `BIT' columns in a table could cause joins that use the table to
     fail.  (Bug#18895 (http://bugs.mysql.com/18895))

   * The build process incorrectly tried to overwrite `sql/lex_hash.h'.
     This caused the build to fail when using a shadow link tree
     pointing to original sources that were owned by another account.
     (Bug#18888 (http://bugs.mysql.com/18888))

   * Setting `myisam_repair_threads' caused any repair operation on a
     `MyISAM' table to fail to update the cardinality of indexes,
     instead making them always equal to 1.  (Bug#18874
     (http://bugs.mysql.com/18874))

   * The MySQL server startup script `/etc/init.d/mysql' (created from
     `mysql.server') is now marked to ensure that the system services
     `ypbind', `nscd', `ldap', and `NTP' are started first (if these are
     configured on the machine).  (Bug#18810
     (http://bugs.mysql.com/18810))

   * `InnoDB': Quoted Unicode identifiers were not handled correctly.
     This included names of tables, columns, and foreign keys.
     (Bug#18800 (http://bugs.mysql.com/18800))

   * Intermediate tables created during the execution of an `ALTER
     TABLE' statement were visible in the output of `SHOW TABLES'.
     (Bug#18775 (http://bugs.mysql.com/18775))

   * `FEDERATED' tables raised invalid duplicate key errors when
     attempting on one server to insert rows having the same primary
     key values as rows that had been deleted from the linked table on
     the other server.  (Bug#18764 (http://bugs.mysql.com/18764))

   * Memory used by scheduled events was not freed when the events were
     dropped.  (Bug#18683 (http://bugs.mysql.com/18683))

   * The implementation for `UNCOMPRESS()' did not indicate that it
     could return `NULL', causing the optimizer to do the wrong thing.
     (Bug#18539 (http://bugs.mysql.com/18539))

   * Referring to a stored function qualified with the name of one
     database and tables in another database caused a `table doesn't
     exist' error.  (Bug#18444 (http://bugs.mysql.com/18444))

   * Identifiers could not contain bytes with a value of 255, though
     that should be allowed as of the identifier-encoding changes made
     in MySQL 5.1.6.  (Bug#18396 (http://bugs.mysql.com/18396))

   * Triggers on tables in the `mysql' database caused a server crash.
     Triggers for tables in this database now are disallowed.
     (Bug#18361 (http://bugs.mysql.com/18361), Bug#18005
     (http://bugs.mysql.com/18005))

   * Incorrect type aggregation for `IN()' and `CASE' expressions could
     lead to an incorrect result.  (Bug#18360
     (http://bugs.mysql.com/18360))

   * The length of the pattern string prefix for `LIKE' operations was
     calculated incorrectly for multi-byte character sets. As a result,
     the scanned range was wider than necessary if the prefix contained
     any multi-byte characters, and rows could be missing from the
     result set.  (Bug#18359 (http://bugs.mysql.com/18359), Bug#16674
     (http://bugs.mysql.com/16674))

   * On Windows, corrected a crash stemming from differences in Visual
     C runtime library routines from POSIX behavior regarding invalid
     file descriptors.  (Bug#18275 (http://bugs.mysql.com/18275))

   * Linking the `pthreads' library to single-threaded MySQL libraries
     caused `dlopen()' to fail at runtime on HP-UX.  (Bug#18267
     (http://bugs.mysql.com/18267))

   * The source distribution failed to compile when configured with the
     `--with-libwrap' option.  (Bug#18246 (http://bugs.mysql.com/18246))

   * On Windows, terminating `mysqld' with Control-C could result in a
     crash during shutdown.  (Bug#18235 (http://bugs.mysql.com/18235))

   * Selecting data from a `MEMORY' table with a `VARCHAR' column and a
     `HASH' index over it returned only the first row matched.
     (Bug#18233 (http://bugs.mysql.com/18233))

   * The use of `MIN()' and `MAX()' on columns with an index prefix
     produced incorrect results in some queries.  (Bug#18206
     (http://bugs.mysql.com/18206))

   * A `UNION' over more than 128 `SELECT' statements that use an
     aggregate function failed.  (Bug#18175
     (http://bugs.mysql.com/18175))

   * The optimizer did not take advantage of indexes on columns used
     for the second or third arguments of `BETWEEN'.  (Bug#18165
     (http://bugs.mysql.com/18165))

   * Performing `INSERT ... SELECT ... JOIN ...  USING' without
     qualifying the column names caused `ERROR 1052 "column 'x' in
     field list is ambiguous"' even in cases where the column
     references were unambiguous.  (Bug#18080
     (http://bugs.mysql.com/18080))

   * An update that used a join of a table to itself and modified the
     table on both sides of the join reported the table as crashed.
     (Bug#18036 (http://bugs.mysql.com/18036))

   * Race conditions on certain platforms could cause the Instance
     Manager to try to restart the same instance multiple times.
     (Bug#18023 (http://bugs.mysql.com/18023))

   * Changing the definition of a `DECIMAL' column with `ALTER TABLE'
     caused loss of column values.  (Bug#18014
     (http://bugs.mysql.com/18014))

   * For table-format output, `mysql' did not always calculate columns
     widths correctly for columns containing multi-byte characters in
     the column name or contents.  (Bug#17939
     (http://bugs.mysql.com/17939))

   * The character set was not being properly initialized for `CAST()'
     with a type like `CHAR(2) BINARY', which resulted in incorrect
     results or even a server crash.  (Bug#17903
     (http://bugs.mysql.com/17903))

   * Checking a `MyISAM' table (using `CHECK TABLE') having a spatial
     index and only one row would wrongly indicate that the table was
     corrupted.  (Bug#17877 (http://bugs.mysql.com/17877))

   * For a reference to a non-existent index in `FORCE INDEX', the
     error message referred to a column, not an index.  (Bug#17873
     (http://bugs.mysql.com/17873))

   * A stored procedure that created and invoked a prepared statement
     was not executed when called in a mysqld init-file.  (Bug#17843
     (http://bugs.mysql.com/17843))

   * It is possible to create `MERGE' tables into which data cannot be
     inserted (by not specifying a `UNION' clause. However, when an
     insert was attempted, the error message was confusing. Now an
     error occurs indicating that the table is read-only.  (Bug#17766
     (http://bugs.mysql.com/17766))

   * Row-based replication failed when the query cache was enabled on
     the slave.  (Bug#17620 (http://bugs.mysql.com/17620))

   * Attempting to insert a string of greater than 4096 bytes into a
     `FEDERATED' table resulted in the error `ERROR 1296 (HY000) at
     line 2: Got error 10000 'Error on remote system: 1054: Unknown
     column 'STRING-VALUE' from FEDERATED'. This error was raised
     regardless of the type of column involved (`VARCHAR', `TEXT', and
     so on.)  (Bug#17608 (http://bugs.mysql.com/17608))

   * If a filename was specified for the `--log' or
     `--log-slow_queries' options but the server was logging to tables
     and not files, the server produced no error message.  (Bug#17599
     (http://bugs.mysql.com/17599))

   * If the general log table reached a large enough file size (27GB),
     `SELECT COUNT(*)' on the table caused a server crash.  (Bug#17589
     (http://bugs.mysql.com/17589))

   * Using the extended syntax for `TRIM()' -- that is, `TRIM(... FROM
     ...)' -- in a `SELECT' statement defining a view caused an invalid
     syntax error when selecting from the view.  (Bug#17526
     (http://bugs.mysql.com/17526))

   * Use of the `--prompt' option or `prompt' command caused `mysql' to
     be unable to connect to the Instance Manager.  (Bug#17485
     (http://bugs.mysql.com/17485))

   * `OPTIMIZE TABLE' and `REPAIR TABLE' yielded incorrect messages or
     warnings when used on partitioned tables.  (Bug#17455
     (http://bugs.mysql.com/17455))

   * `mysqldump' would not dump views that had become invalid because a
     table named in the view definition had been dropped. Instead, it
     quit with an error message. Now you can specify the `--force'
     option to cause `mysqldump' to keep going and write a SQL comment
     containing the view definition to the dump output.  (Bug#17371
     (http://bugs.mysql.com/17371))

   * `N'xxx'' and `_utf8'xxx'' were not treated as equivalent because
     `N'xxx'' failed to unescape backslashes (`\') and doubled
     apostrophe/single quote characters (`''').  (Bug#17313
     (http://bugs.mysql.com/17313))

   * Following a failed attempt to add an index to an `ARCHIVE' table,
     it was no longer possible to drop the database in which the table
     had been created.  (Bug#17310 (http://bugs.mysql.com/17310))

   * Assignments of values to variables of type `TEXT' were handled
     incorrectly in stored routines.  (Bug#17225
     (http://bugs.mysql.com/17225))

   * Views created from prepared statements inside of stored procedures
     were created with a definition that included both `SQL_CACHE' and
     `SQL_NO_CACHE'.  (Bug#17203 (http://bugs.mysql.com/17203))

   * `mysqldump' wrote an extra pair of `DROP DATABASE' and `CREATE
     DATABASE' statements if run with the `--add-drop-database' option
     and the database contained views.  (Bug#17201
     (http://bugs.mysql.com/17201))

   * A `Table ... doesn't exist' error could occur for statements that
     called a function defined in another database.  (Bug#17199
     (http://bugs.mysql.com/17199))

   * A prepared statement that altered partitioned table within a
     stored procedure failed with the error `Unknown prepared statement
     handler'.  (Bug#17138 (http://bugs.mysql.com/17138))

   * `myisam_ftdump' would fail when trying to open a MyISAM index file
     that you did not have write permissions to access, even though the
     command would only be reading from the file.  (Bug#17122
     (http://bugs.mysql.com/17122))

   * `ALTER TABLE' on a table created prior to 5.0.3 would cause table
     corruption if the `ALTER TABLE' did one of the following:

        * Change the default value of a column.

        * Change the table comment.

        * Change the table password.

     (Bug#17001 (http://bugs.mysql.com/17001))

   * For statements that have a `DEFINER' clause such as `CREATE
     TRIGGER' or `CREATE VIEW', long usernames or hostnames could cause
     a buffer overflow.  (Bug#16899 (http://bugs.mysql.com/16899))

   * The `PASSWORD()' function returned invalid results when used in
     some `UNION' queries.  (Bug#16881 (http://bugs.mysql.com/16881))

   * `ORDER BY RAND() LIMIT 1' always set a user variable to the last
     possible value from the table.  (Bug#16861
     (http://bugs.mysql.com/16861))

   * Compilation on Windows would fail if row based replication was
     disabled using `--without-row-based-replication'.  (Bug#16837
     (http://bugs.mysql.com/16837))

   * Queries containing a subquery that used aggregate functions could
     return incorrect results.  (Bug#16792
     (http://bugs.mysql.com/16792))

   * Concatenating the results of multiple constant subselects produced
     incorrect results.  (Bug#16716 (http://bugs.mysql.com/16716))

   * When performing a `GROUP_CONCAT()', the server transformed `BLOB'
     columns `VARCHAR' columns, which could cause erroneous results
     when using Connector/J and possibly other MySQL APIs.  (Bug#16712
     (http://bugs.mysql.com/16712))

   * Stored procedures did not use the character set defined for the
     database in which they were created.  (Bug#16676
     (http://bugs.mysql.com/16676))

   * Some server errors were not reported to the client, causing both
     to try to read from the connection until a hang or crash resulted.
     (Bug#16581 (http://bugs.mysql.com/16581))

   * If the files for an open table were removed at the OS level
     (external to the server), the server exited with an assertion
     failure.  (Bug#16532 (http://bugs.mysql.com/16532))

   * On Windows, a definition for *Note `mysql_set_server_option()':
     mysql-set-server-option.  was missing from the C client library.
     (Bug#16513 (http://bugs.mysql.com/16513))

   * `mysqlcheck' tried to check views instead of ignoring them.
     (Bug#16502 (http://bugs.mysql.com/16502))

   * Updating a column of a `FEDERATED' table to `NULL' sometimes
     failed.  (Bug#16494 (http://bugs.mysql.com/16494))

   * For `SELECT ... FOR UPDATE' statements that used `DISTINCT' or
     `GROUP BY' over all key parts of a unique index (or primary key),
     the optimizer unnecessarily created a temporary table, thus losing
     the linkage to the underlying unique index values. This caused a
     `Result set not updatable' error. (The temporary table is
     unnecessary because under these circumstances the distinct or
     grouped columns must also be unique.)  (Bug#16458
     (http://bugs.mysql.com/16458))

   * A scheduled event that took longer to execute than the length of
     time scheduled between successive executions could `skip'
     executions. For example, an event defined with `EVERY 1 SECOND' --
     but which required longer than 1 second to complete -- might be
     executed only once every 2 seconds.  (Bug#16417
     (http://bugs.mysql.com/16417))

   * A subselect used in the `ON SCHEDULE' clause of a `CREATE EVENT'
     or `ALTER EVENT' statement caused the server to crash, rather than
     producing an error as expected.  (Bug#16394
     (http://bugs.mysql.com/16394))

   * Grant table modifications sometimes did not refresh the in-memory
     tables if the hostname was `''' or not specified.  (Bug#16297
     (http://bugs.mysql.com/16297))

   * A subquery in the `WHERE' clause of the outer query and using `IN'
     and `GROUP BY' returned an incorrect result.  (Bug#16255
     (http://bugs.mysql.com/16255))

   * A query could produce different results with and without and
     index, if the `WHERE' clause contained a range condition that used
     an invalid `DATETIME' constant.  (Bug#16249
     (http://bugs.mysql.com/16249))

   * `TIMESTAMPDIFF()' examined only the date and ignored the time when
     the requested difference unit was months or quarters.  (Bug#16226
     (http://bugs.mysql.com/16226))

   * Using tables from MySQL 4.x in MySQL 5.x, in particular those with
     `VARCHAR' fields and using `INSERT DELAYED' to update data in the
     table would result in either data corruption or a server crash.
     (Bug#16218 (http://bugs.mysql.com/16218), Bug#17294
     (http://bugs.mysql.com/17294), Bug#16611
     (http://bugs.mysql.com/16611))

   * The value returned by a stored function returning a string value
     was not of the declared character set.  (Bug#16211
     (http://bugs.mysql.com/16211))

   * The `index_merge'/`Intersection' optimizer could experience a
     memory overrun when the number of table columns covered by an
     index was sufficiently large, possibly resulting in a server crash.
     (Bug#16201 (http://bugs.mysql.com/16201))

   * Row equalities (such as `WHERE (a,b) = (c,d)' were not taken into
     account by the optimizer, resulting in slow query execution. Now
     they are treated as conjunctions of equalities between row
     elements.  (Bug#16081 (http://bugs.mysql.com/16081))

   * Some memory leaks in the `libmysqld' embedded server were
     corrected.  (Bug#16017 (http://bugs.mysql.com/16017))

   * Values greater than 2 gigabytes used in the VALUES LESS THAN
     clause of a table partitioned by RANGE were treated as negative
     numbers.  (Bug#16002 (http://bugs.mysql.com/16002))

   * A `CREATE TABLE' that produced a `The PARTITION function returns
     the wrong type' error also caused an `Incorrect information in
     file' to be printed to `STDERR', and a junk file to be left in the
     database directory.  (Bug#16000 (http://bugs.mysql.com/16000))

   * The `max_length' metadata value for columns created from
     `CONCAT()' could be incorrect when the collation of an argument
     differed from the collation of the `CONCAT()' itself. In some
     contexts such as `UNION', this could lead to truncation of the
     column contents.  (Bug#15962 (http://bugs.mysql.com/15962))

   * When `NOW()' was used in a `BETWEEN' clause of the definition for
     a view, it was replaced with a constant in the view.  (Bug#15950
     (http://bugs.mysql.com/15950))

   * The server's handling of the number of partitions or subpartitions
     specified in a `PARTITIONS' or `SUBPARTITIONS' clause was changed.
     Beginning with this release, the number of partitions must:

        * be a positive, non-zero integer

        * not have any leading zeroes

        * not be an expression

     Also beginning with this version, no attempt is made to convert,
     truncate, or evaluate a `PARTITIONS' or `SUBPARTITIONS' value;
     instead, the `CREATE TABLE' or `ALTER TABLE' statement containing
     the `PARTITIONS' or `SUBPARTITIONS' clause now fails with an
     appropriate error message.  (Bug#15890
     (http://bugs.mysql.com/15890))

   * Long multiple-row `INSERT' statements could take a very long time
     for some multi-byte character sets.  (Bug#15811
     (http://bugs.mysql.com/15811))

   * The C API failed to return a status message when invoking a stored
     procedure.  (Bug#15752 (http://bugs.mysql.com/15752))

   * `mysqlimport' sends a `set @@character_set_database=binary'
     statement to the server, but this is not understood by pre-4.1
     servers. Now `mysqlimport' encloses the statement within a
     `/*!40101 ... */' comment so that old servers will ignore it.
     (Bug#15690 (http://bugs.mysql.com/15690))

   * `DELETE' with `LEFT JOIN' for `InnoDB' tables could crash the
     server if `innodb_locks_unsafe_for_binlog' was enabled.
     (Bug#15650 (http://bugs.mysql.com/15650))

   * `BIN()', `OCT()', and `CONV()' did not work with BIT values.
     (Bug#15583 (http://bugs.mysql.com/15583))

   * Nested natural joins worked executed correctly when executed as a
     non-prepared statement could fail with an `Unknown column
     'COL_NAME' in 'field list'' error when executed as a prepared
     statement, due to a name resolution problem.  (Bug#15355
     (http://bugs.mysql.com/15355))

   * The `MD5()' and `SHA()' functions treat their arguments as
     case-sensitive strings. But when they are compared, their
     arguments were compared as case-insensitive strings, which leads
     to two function calls with different arguments (and thus different
     results) compared as being identical. This can lead to a wrong
     decision made in the range optimizer and thus to an incorrect
     result set.  (Bug#15351 (http://bugs.mysql.com/15351))

   * Invalid escape sequences in option files caused MySQL programs
     that read them to abort.  (Bug#15328 (http://bugs.mysql.com/15328))

   * `SHOW GRANTS FOR CURRENT_USER' did not return definer grants when
     executed in `DEFINER' context (such as within a stored prodedure
     defined with `SQL SECURITY DEFINER'), it returned the invoker
     grants.  (Bug#15298 (http://bugs.mysql.com/15298))

   * The `--collation-server' server option was being ignored. With the
     fix, if you choose a non-default character set with
     `--character-set-server', you should also use `--collation-server'
     to specify the collation.  (Bug#15276
     (http://bugs.mysql.com/15276))

   * Re-executing a stored procedure with a complex stored procedure
     cursor query could lead to a server crash.  (Bug#15217
     (http://bugs.mysql.com/15217))

   * The server crashed if it tried to access a `CSV' table for which
     the data file had been removed.  (Bug#15205
     (http://bugs.mysql.com/15205))

   * When using tables containing `VARCHAR' columns created under MySQL
     4.1 with a 5.0 or later server, for some queries the metadata sent
     to the client could have an empty column name.  (Bug#14897
     (http://bugs.mysql.com/14897))

   * An invalid comparison between keys with index prefixes over
     multi-byte character fields could lead to incorrect result sets if
     the selected query execution plan used a range scan by an index
     prefix over a `UTF8' character field.  This also caused incorrect
     results under similar circumstances with many other character sets.
     (Bug#14896 (http://bugs.mysql.com/14896))

   * When setting a column to its implicit default value as the result
     of inserting a `NULL' into a `NOT NULL' column as part of a
     multi-row insert or `LOAD DATA' operation, the server returned a
     misleading warning message.  (Bug#14770
     (http://bugs.mysql.com/14770))

   * For `BOOLEAN' mode full-text searches on non-indexed columns,
     `NULL' rows generated by a `LEFT JOIN' caused incorrect query
     results.  (Bug#14708 (http://bugs.mysql.com/14708), Bug#25637
     (http://bugs.mysql.com/25637))

   * The parser rejected queries that selected from a table twice using
     a `UNION' within a subquery. The parser now supports arbitrary
     subquery, join, and parenthesis operations within `EXISTS'
     subqueries. A limitation still exists for scalar subqueries: If
     the subquery contains `UNION', the first `SELECT' of the `UNION'
     cannot be within parentheses. For example, `SELECT (SELECT a FROM
     t1 UNION SELECT b FROM t2)' will work, but `SELECT ((SELECT a FROM
     t1) UNION (SELECT b FROM t2))' will not.  (Bug#14654
     (http://bugs.mysql.com/14654))

   * Using `SELECT' and a table join while running a concurrent
     `INSERT' operation would join incorrect rows.  (Bug#14400
     (http://bugs.mysql.com/14400))

   * Prepared statements caused general log and server memory
     corruption.  (Bug#14346 (http://bugs.mysql.com/14346))

   * The binary log lacked character set information for table names
     when dropping temporary tables.  (Bug#14157
     (http://bugs.mysql.com/14157))

   * `libmysqld' produced some warnings to `stderr' which could not be
     silenced. These warnings now are suppressed.  (Bug#13717
     (http://bugs.mysql.com/13717))

   * RPM packages had spurious dependencies on Perl modules and other
     programs.  (Bug#13634 (http://bugs.mysql.com/13634))

   * `InnoDB' locking was improved by removing a gap lock for the case
     that you try to delete the same row twice within a transaction.
     (Bug#13544 (http://bugs.mysql.com/13544))

   * `REPLACE' statements caused activation of `UPDATE' triggers, not
     `DELETE' and `INSERT' triggers.  (Bug#13479
     (http://bugs.mysql.com/13479))

   * The source distribution failed to compile when configured with the
     `--without-geometry' option.  (Bug#12991
     (http://bugs.mysql.com/12991))

   * With settings of `read_buffer_size' >= 2G and
     `read_rnd_buffer_size' >=2G, `LOAD DATA INFILE' failed with no
     error message or caused a server crash for files larger than 2GB.
     (Bug#12982 (http://bugs.mysql.com/12982))

   * A `B-TREE' index on a `MEMORY' table erroneously reported
     duplicate entry error for multiple `NULL' values.  (Bug#12873
     (http://bugs.mysql.com/12873))

   * Instance Manager didn't close the client socket file when starting
     a new `mysqld' instance.  `mysqld' inherited the socket, causing
     clients connected to Instance Manager to hang.  (Bug#12751
     (http://bugs.mysql.com/12751))

   * On Mac OS X, zero-byte `read()' or `write()' calls to an
     SMB-mounted filesystem could return a non-standard return value,
     leading to data corruption. Now such calls are avoided.
     (Bug#12620 (http://bugs.mysql.com/12620))

   * `DATE_ADD()' and `DATE_SUB()' returned `NULL' when the result date
     was on the day `'9999-12-31''.  (Bug#12356
     (http://bugs.mysql.com/12356))

   * For very complex `SELECT' statements could create temporary tables
     that were too large, and for which the temporary files were not
     removed, causing subsequent queries to fail.  (Bug#11824
     (http://bugs.mysql.com/11824))

   * After an `INSERT ... ON DUPLICATE KEY UPDATE' statement that
     updated an existing row, `LAST_INSERT_ID()' could return a value
     not in the table.  (Bug#11460 (http://bugs.mysql.com/11460))

   * `USE' did not refresh database privileges when employed to
     re-select the current database.  (Bug#10979
     (http://bugs.mysql.com/10979))

   * The server returns a more informative error message when it
     attempts to open a `MERGE' table that has been defined to use
     non-`MyISAM' tables.  (Bug#10974 (http://bugs.mysql.com/10974))

   * The type of the value returned by the `VARIANCE()' function varied
     according to the type of the input value. The function should
     always return a `DOUBLE' value.  (Bug#10966
     (http://bugs.mysql.com/10966))

   * The same trigger error message was produced under two conditions:
     The trigger duplicated an existing trigger name, or the trigger
     duplicated an existing combination of action and event. Now
     different messages are produced for the two conditions so as to be
     more informative.  (Bug#10946 (http://bugs.mysql.com/10946))

   * A locking safety check in `InnoDB' reported a spurious error
     `stored_select_lock_type is 0 inside ::start_stmt()' for `INSERT
     ...  SELECT' statements in `innodb_locks_unsafe_for_binlog' mode.
     The safety check was removed.  (Bug#10746
     (http://bugs.mysql.com/10746))

   * `CREATE USER' did not respect the 16-character username limit.
     (Bug#10668 (http://bugs.mysql.com/10668))

   * A server or network failure with an open client connection would
     cause the client to hang even though the server was no longer
     available.

     As a result of this change, the `MYSQL_OPT_READ_TIMEOUT' and
     `MYSQL_OPT_WRITE_TIMEOUT' options for *Note `mysql_options()':
     mysql-options. now apply to TCP/IP connections on all platforms.
     Previously, they applied only to Windows.  (Bug#9678
     (http://bugs.mysql.com/9678))

   * `INSERT INTO ... SELECT ... LIMIT 1' could be slow because the
     `LIMIT' was ignored when selecting candidate rows.  (Bug#9676
     (http://bugs.mysql.com/9676))

   * The optimizer could produce an incorrect result after `AND' with
     collations such as `latin1_german2_ci', `utf8_czech_ci', and
     `utf8_lithianian_ci'.  (Bug#9509 (http://bugs.mysql.com/9509))

   * The `DATA DIRECTORY' table option did not work for `TEMPORARY'
     tables.  (Bug#8706 (http://bugs.mysql.com/8706))

   * A stored procedure with a `CONTINUE' handler that encountered an
     error continued to execute a statement that caused an error,
     rather with the next statement following the one that caused the
     error.  (Bug#8153 (http://bugs.mysql.com/8153))

   * For ODBC compatibility, MySQL supports use of `WHERE COL_NAME IS
     NULL' for `DATE' or `DATETIME' columns that are `NOT NULL', to
     allow column values of `'0000-00-00'' or `'0000-00-00 00:00:00''
     to be selected. However, this was not working for `WHERE' clauses
     in `DELETE' statements.  (Bug#8143 (http://bugs.mysql.com/8143))

   * A user variable set to a value selected from an unsigned column
     was stored as a signed value.  (Bug#7498
     (http://bugs.mysql.com/7498))

   * The `--with-collation' option was not honored for client
     connections.  (Bug#7192 (http://bugs.mysql.com/7192))

   * An invalid `GRANT' statement for which `Ok' was returned on a
     replication master caused an error on the slave and replication to
     fail.  (Bug#6774 (http://bugs.mysql.com/6774))

   * With `TRADITIONAL' SQL mode, assignment of out-of-bound values and
     rounding of assigned values was done correctly, but assignment of
     the same numbers represented as strings sometimes was handled
     differently.  (Bug#6147 (http://bugs.mysql.com/6147))

   * On an `INSERT' into an updatable but non-insertable view, an error
     message was issued stating that the view was not updatable. Now
     the message says the view is not insertable-into.  (Bug#5505
     (http://bugs.mysql.com/5505))

   * `EXPLAIN' sometimes returned an incorrect `select_type' for a
     `SELECT' from a view, compared to the `select_type' for the
     equivalent `SELECT' from the base table.  (Bug#5500
     (http://bugs.mysql.com/5500))

   * Some queries that used `ORDER BY' and `LIMIT' performed quickly in
     MySQL 3.23, but slowly in MySQL 4.x/5.x due to an optimizer
     problem.  (Bug#4981 (http://bugs.mysql.com/4981))

   * Incorporated portability fixes into the definition of
     `__attribute__' in `my_global.h'.  (Bug#2717
     (http://bugs.mysql.com/2717))

   * User-created tables having a name beginning with `#sql' were not
     visible to `SHOW TABLES' and could collide with internal temporary
     table names. Now they are not hidden and do not collide.
     (Bug#1405 (http://bugs.mysql.com/1405))

   * not have any leading zeroes

   * not be an expression

   * be a positive, non-zero integer


File: manual.info,  Node: news-5-1-11,  Next: news-5-1-10,  Prev: news-5-1-12,  Up: news-5-1-x

C.1.19 Changes in MySQL 5.1.11 (26 May 2006)
--------------------------------------------

This is a new Beta development release, fixing recently discovered bugs.

This section documents all changes and bug fixes that have been applied
since the last official MySQL release. If you would like to receive
more fine-grained and personalized _update alerts_ about fixes that are
relevant to the version and features you use, please consider
subscribing to _MySQL Enterprise_ (a commercial MySQL offering). For
more details please see `http://www.mysql.com/products/enterprise'.

Functionality added or changed:

   * *Incompatible Change*: The Event Scheduler can now be in one of
     three states (on, off, or the new suspended state). In addition,
     due to the fact that `SET GLOBAL event_scheduler;' now acts in a
     synchronous rather than asynchronous manner, the Event Scheduler
     thread can be no longer be activated or deactivated at run time.

     For more information regarding these changes, see *Note
     events-overview::.  (Bug#17619 (http://bugs.mysql.com/17619))

   * *MySQL Cluster*: The limit of 2048 ordered indexes per cluster has
     been lifted.  There is now no upper limit on the number of ordered
     indexes (including `AUTO_INCREMENT' columns) that may be used.
     (Bug#14509 (http://bugs.mysql.com/14509))

   * Added the `log_queries_not_using_indexes' system variable.
     (Bug#19616 (http://bugs.mysql.com/19616))

   * Added the `ssl_ca', `ssl_capath', `ssl_cert', `ssl_cipher', and
     `ssl_key' system variables, which display the values given via the
     corresponding command options. See *Note ssl-options::.
     (Bug#19606 (http://bugs.mysql.com/19606))

   * The `ENABLE KEYS' and `DISABLE KEYS' clauses for the `ALTER TABLE'
     statement are now supported for partitioned tables.  (Bug#19502
     (http://bugs.mysql.com/19502))

   * Added the `--ssl-verify-server-cert' option to MySQL client
     programs. This option causes the server's Common Name value in its
     certificate to be verified against the hostname used when
     connecting to the server, and the connection is rejected if there
     is a mismatch. Added `MYSQL_OPT_SSL_VERIFY_SERVER_CERT' option for
     the *Note `mysql_options()': mysql-options. C API function to
     enable this verification. This feature can be used to prevent
     man-in-the-middle attacks. Verification is disabled by default.
     (Bug#17208 (http://bugs.mysql.com/17208))

   * The default for the `innodb_thread_concurrency' system variable
     was changed to `8'.  (Bug#15868 (http://bugs.mysql.com/15868))

   * It is now possible to use `NEW.VAR_NAME' values within triggers as
     `INOUT' parameters to stored procedures.  (Bug#14635
     (http://bugs.mysql.com/14635))

   * Added the `--angel-pid-file' option to `mysqlmanager' for
     specifying the file in which the angel process records its process
     ID when `mysqlmanager' runs in daemon mode.  (Bug#14106
     (http://bugs.mysql.com/14106))

   * Previously, to build MySQL from source with SSL support enabled,
     you would invoke `configure' with either the `--with-openssl' or
     `--with-yassl' option. Those options both have been replaced by the
     `--with-ssl' option. By default, `--with-ssl' causes the bundled
     yaSSL library to be used. To select OpenSSL instead, give the
     option as `--with-ssl=PATH ', where PATH is the directory where the
     OpenSSL header files and libraries are located.

   * The *Note `mysql_get_ssl_cipher()': mysql-get-ssl-cipher. C API
     function was added.

   * `mysql_explain_log' (a third-party program) is no longer included
     in MySQL distributions.

Bugs fixed:

   * *Security Fix*: An SQL-injection security hole has been found in
     multi-byte encoding processing. The bug was in the server,
     incorrectly parsing the string escaped with the *Note
     `mysql_real_escape_string()': mysql-real-escape-string.  C API
     function.

     This vulnerability was discovered and reported by Josh Berkus
     <josh@postgresql.org> and Tom Lane <tgl@sss.pgh.pa.us> as part of
     the inter-project security collaboration of the OSDB consortium.
     For more information about SQL injection, please see the following
     text.

     Discussion

     An SQL injection security hole has been found in multi-byte
     encoding processing. An SQL injection security hole can include a
     situation whereby when a user supplied data to be inserted into a
     database, the user might inject SQL statements into the data that
     the server will execute. With regards to this vulnerability, when
     character set-unaware escaping is used (for example,
     `addslashes()' in PHP), it is possible to bypass the escaping in
     some multi-byte character sets (for example, SJIS, BIG5 and GBK).
     As a result, a function such as `addslashes()' is not able to
     prevent SQL-injection attacks. It is impossible to fix this on the
     server side. The best solution is for applications to use
     character set-aware escaping offered by a function such *Note
     `mysql_real_escape_string()': mysql-real-escape-string.

     However, a bug was detected in how the MySQL server parses the
     output of *Note `mysql_real_escape_string()':
     mysql-real-escape-string. As a result, even when the character
     set-aware function *Note `mysql_real_escape_string()':
     mysql-real-escape-string.  was used, SQL injection was possible.
     This bug has been fixed.

     Workarounds

     If you are unable to upgrade MySQL to a version that includes the
     fix for the bug in *Note `mysql_real_escape_string()':
     mysql-real-escape-string.  parsing, but run MySQL 5.0.1 or higher,
     you can use the `NO_BACKSLASH_ESCAPES' SQL mode as a workaround.
     (This mode was introduced in MySQL 5.0.1.)  `NO_BACKSLASH_ESCAPES'
     enables an SQL standard compatibility mode, where backslash is not
     considered a special character. The result will be that queries
     will fail.

     To set this mode for the current connection, enter the following
     SQL statement:

          SET sql_mode='NO_BACKSLASH_ESCAPES';

     You can also set the mode globally for all clients:

          SET GLOBAL sql_mode='NO_BACKSLASH_ESCAPES';

     This SQL mode also can be enabled automatically when the server
     starts by using the command-line option
     `--sql-mode=NO_BACKSLASH_ESCAPES' or by setting
     `sql-mode=NO_BACKSLASH_ESCAPES' in the server option file (for
     example, `my.cnf' or `my.ini', depending on your system).
     (Bug#8378 (http://bugs.mysql.com/8378), CVE-2006-2753
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2753)) See
     also Bug#8303 (http://bugs.mysql.com/8303)

   * *Partitioning*: *MySQL Cluster*: `SELECT MIN(UNIQUE_COLUMN)' from a
     Cluster table with user-defined partitioning crashed the server.
     (Bug#18730 (http://bugs.mysql.com/18730))

   * *MySQL Cluster*: Running `ALL START' in the `NDB' management
     client or restarting multiple nodes simultaneously could under
     some circumstances cause the cluster to crash.  (Bug#19930
     (http://bugs.mysql.com/19930))

   * *MySQL Cluster*: (Replication): Memory was not freed after some
     `ALTER TABLE' operations, which could cause `mysqld' processes to
     crash.  (Bug#19885 (http://bugs.mysql.com/19885))

   * *MySQL Cluster*: (NDBAPI): On big-endian platforms,
     `NdbOperation::write_attr()' did not update 32-bit fields
     correctly.  (Bug#19537 (http://bugs.mysql.com/19537))

   * *MySQL Cluster*: `TRUNCATE' failed on tables having `BLOB' or
     `TEXT' columns with the error `Lock wait timeout exceeded'.

     *Note*:

     This issue affected both in-memory and Disk Data tables.

     (Bug#19201 (http://bugs.mysql.com/19201))

   * *MySQL Cluster*: `ALTER TABLE ENGINE=...' failed when used to
     change a MySQL Cluster table having no explicit primary key to use
     a different storage engine.

     *Note*:

     As a consequence of this fix, `SHOW CREATE TABLE' no longer
     displays auto-partitioning information for `NDBCLUSTER' tables.

     (Bug#19010 (http://bugs.mysql.com/19010))

   * *MySQL Cluster*: (NDBAPI): The `Ndb::dropEventOperation()' method
     failed to clean up all objects used, which could cause memory
     leaks to occur.  (Bug#17610 (http://bugs.mysql.com/17610))

   * *MySQL Cluster*: Using `stale' `mysqld' `.FRM' files could cause a
     newly-restored cluster to fail. This situation could arise when
     restarting a MySQL Cluster using the `--intial' option while
     leaving connected `mysqld' processes running.  (Bug#16875
     (http://bugs.mysql.com/16875))

   * *MySQL Cluster*: A Cluster whose storage nodes were installed from
     the `MySQL-ndb-storage-* ' RPMs could not perform `CREATE' or
     `ALTER' operations that made use of non-default character sets or
     collations.  (Bug#14918 (http://bugs.mysql.com/14918))

   * *MySQL Cluster*: Data node failures could cause excessive CPU
     usage by `ndb_mgmd'.  (Bug#13987 (http://bugs.mysql.com/13987))

   * *Cluster Replication*: `mysqld' processes did not always detect
     cluster shutdown, leading to issues with Cluster replication and
     schema distribution.  (Bug#19395 (http://bugs.mysql.com/19395))

   * The `Data_free' column in the output of `SHOW TABLE STATUS' always
     displayed 0 for partitioned tables.  (Bug#19501
     (http://bugs.mysql.com/19501))

   * Altering a `VARCHAR' column in a `MyISAM' table to make it longer
     could cause corruption of the following column.  (Bug#19386
     (http://bugs.mysql.com/19386))

   * In was not possible to invoke a stored routine containing dynamic
     SQL from a scheduled event.  (Bug#19264
     (http://bugs.mysql.com/19264))

   * Adding an index to a table created using partitioning by `KEY' and
     the `MEMORY' storage engine caused the server to crash.
     (Bug#19140 (http://bugs.mysql.com/19140))

   * Use of uninitialized user variables in a subquery in the `FROM'
     clause resulted in invalid entries in the binary log.  (Bug#19136
     (http://bugs.mysql.com/19136))

   * A `CREATE TABLE' statement that created a table from a
     materialized view did not inherit default values from the
     underlying table.  (Bug#19089 (http://bugs.mysql.com/19089))

   * Premature optimization of nested subqueries in the `FROM' clause
     that refer to aggregate functions could lead to incorrect results.
     (Bug#19077 (http://bugs.mysql.com/19077))

   * When creating a table using `CREATE TABLE ... PARTITION BY ...
     SELECT ...', the partitioning clause was ignored.  (Bug#19062
     (http://bugs.mysql.com/19062))

   * For dates with 4-digit year parts less than 200, an implicit
     conversion to add a century was applied for date arithmetic
     performed with `DATE_ADD()', `DATE_SUB()', `+ INTERVAL', and `-
     INTERVAL'. (For example, `DATE_ADD('0050-01-01 00:00:00', INTERVAL
     0 SECOND)' became `'2050-01-01 00:00:00''.) Now these operations
     return `NULL' rather than an incorrect non-`NULL' value.
     (Bug#18997 (http://bugs.mysql.com/18997))

   * `BLOB' or `TEXT' arguments to or values returned from stored
     functions were not copied properly if too long and could become
     garbled.  (Bug#18587 (http://bugs.mysql.com/18587))

   * The embedded server crashed with row-based replication enabled.
     (Bug#18518 (http://bugs.mysql.com/18518))

   * The client libraries were not compiled for position-independent
     code on Solaris-SPARC and AMD x86_64 platforms.  (Bug#18091
     (http://bugs.mysql.com/18091), Bug#13159
     (http://bugs.mysql.com/13159), Bug#14202
     (http://bugs.mysql.com/14202))

   * Returning the value of a system variable from a stored function
     caused a server crash.  (Bug#18037 (http://bugs.mysql.com/18037))

   * Revised memory allocation for local objects within stored
     functions and triggers to avoid memory leak for repeated function
     or trigger invocation.  (Bug#17260 (http://bugs.mysql.com/17260))

   * Symlinking `.mysql_history' to `/dev/null' to suppress statement
     history saving by `mysql' did not work.  (`mysql' deleted the
     symlink and recreated `.mysql_history' as a regular file, and then
     wrote history to it.)  (Bug#16803 (http://bugs.mysql.com/16803))

   * `IS_USED_LOCK()' could return an incorrect connection identifier.
     (Bug#16501 (http://bugs.mysql.com/16501))

   * Simultaneous scheduled events whose actions conflicted with one
     another could crash the server.  (Bug#16428
     (http://bugs.mysql.com/16428))

   * Concurrent reading and writing of privilege structures could crash
     the server.  (Bug#16372 (http://bugs.mysql.com/16372))

   * The server no longer uses a signal handler for signal 0 because it
     could cause a crash on some platforms.  (Bug#15869
     (http://bugs.mysql.com/15869))

   * `EXPLAIN ... SELECT INTO' caused the client to hang.  (Bug#15463
     (http://bugs.mysql.com/15463))

   * `CREATE TABLE ... SELECT ...' statements that used a stored
     function explicitly or implicitly (through a view) resulted in a
     `Table not locked' error.  (Bug#15137
     (http://bugs.mysql.com/15137), Bug#12472
     (http://bugs.mysql.com/12472))

   * Display better error message for `ALTER TABLE' operations that
     will result in duplicate keys due to `AUTO_INCREMENT' resequencing.
     (Bug#14573 (http://bugs.mysql.com/14573))

   * The result from `CONV()' is a string, but was not always treated
     the same way as a string when converted to a real value for an
     arithmetic operation.  (Bug#13975 (http://bugs.mysql.com/13975))

   * Within a trigger, `SET' used the SQL mode of the invoking
     statement, not the mode in effect at trigger creation time.
     (Bug#6951 (http://bugs.mysql.com/6951))

   * Corrected several problems with the treatment of the `--log-error'
     option by `mysqld_safe'. These problems were manifest as
     differences from `mysqld' in error log handling.

        * If a filename was given for `--log-error', `mysqld_safe'
          ignored it and did not pass it to `mysqld', which then wrote
          error information to `stderr' and resulted in incorrect log
          rotation when `FLUSH LOGS' was used.

        * `mysql_safe' now adds `.err' to the end of the filename if no
          extension is present (the same as `mysqld').

        * `mysqld_safe' treated a relative pathname as relative to its
          own current working directory. Now it treats a relative
          pathname as relative to the data directory (the same as
          `mysqld').

     In addition, some argument quoting problems were corrected.
     (Bug#6061 (http://bugs.mysql.com/6061))

   * The `basedir' and `tmpdir' system variables could not be accessed
     via `@@VAR_NAME' syntax.  (Bug#1039 (http://bugs.mysql.com/1039))

   * `mysqld_safe' treated a relative pathname as relative to its own
     current working directory. Now it treats a relative pathname as
     relative to the data directory (the same as `mysqld').

   * `mysql_safe' now adds `.err' to the end of the filename if no
     extension is present (the same as `mysqld').

   * If a filename was given for `--log-error', `mysqld_safe' ignored
     it and did not pass it to `mysqld', which then wrote error
     information to `stderr' and resulted in incorrect log rotation
     when `FLUSH LOGS' was used.

   * The patch for Bug#8303 (http://bugs.mysql.com/8303) broke the fix
     for Bug#8378 (http://bugs.mysql.com/8378) and was reverted.

     In string literals with an escape character (`\') followed by a
     multi-byte character that had (`\') as its second byte, the
     literal was not interpreted correctly. Now only next byte now is
     escaped, and not the entire multi-byte character. This means it a
     strict reverse of the *Note `mysql_real_escape_string()':
     mysql-real-escape-string.  function.


File: manual.info,  Node: news-5-1-10,  Next: news-5-1-9,  Prev: news-5-1-11,  Up: news-5-1-x

C.1.20 Changes in MySQL 5.1.10 (Not released)
---------------------------------------------

*Note*:

This was an internal release only, and no binaries were published.

MySQL 5.1.10 includes the patches for recently reported security
vulnerabilites in the MySQL client-server protocol. We would like to
thank Stefano Di Paola <stefano.dipaola@wisec.it> for finding and
reporting these to us.

This section documents all changes and bug fixes that have been applied
since the last official MySQL release. If you would like to receive
more fine-grained and personalized _update alerts_ about fixes that are
relevant to the version and features you use, please consider
subscribing to _MySQL Enterprise_ (a commercial MySQL offering). For
more details please see `http://www.mysql.com/products/enterprise'.

Functionality added or changed:

   * *Security Enhancement*: Added the global `max_prepared_stmt_count'
     system variable to limit the total number of prepared statements
     in the server. This limits the potential for denial-of-service
     attacks based on running the server out of memory by preparing
     huge numbers of statements. The current number of prepared
     statements is available through the `prepared_stmt_count' system
     variable.  (Bug#16365 (http://bugs.mysql.com/16365))

   * *MySQL Cluster*: It is now possible to restore a MySQL Cluster
     backup between big-endian and little-endian machines.  (Bug#19255
     (http://bugs.mysql.com/19255))

   * *MySQL Cluster*: It is now possible to perform a partial start of
     a cluster. That is, it is now possible to bring up the cluster
     without first running `ndbd `--initial'' on all configured data
     nodes.  (Bug#18606 (http://bugs.mysql.com/18606))

   * *MySQL Cluster*: It is now possible to install MySQL with Cluster
     support to a non-default location and change the search path for
     font description files using either the `--basedir' or
     `--character-sets-dir' options. (Previously in MySQL 5.1, `ndbd'
     searched only the default path for character sets.)

   * *Packaging*: The `MySQL-shared-compat-5.1.X-.i386.rpm' shared
     compatibility RPMs no longer contain libraries for MySQL 5.0. This
     avoids a conflict because the 5.0 and 5.1 libraries share the same
     `soname' number. They now contain libraries for MySQL 3.23, 4.0,
     4.1, and 5.1.  (Bug#19288 (http://bugs.mysql.com/19288))

   * SQL syntax for prepared statements now supports `ANALYZE TABLE',
     `OPTIMIZE TABLE', and `REPAIR TABLE'.  (Bug#19308
     (http://bugs.mysql.com/19308))

   * The `ONLY_FULL_GROUP_BY' SQL mode now also applies to the `HAVING'
     clause. That is, columns not named in the `GROUP BY' clause cannot
     be used in the `HAVING' clause if not used in an aggregate
     function.  (Bug#18739 (http://bugs.mysql.com/18739))

   * XPath expressions passed to the `ExtractValue()' and `UpdateXML()'
     functions can now include the colon character (` `:' '). This
     enables use of these functions with XML which employs namespaces.
     (Bug#18170 (http://bugs.mysql.com/18170))

   * On Windows, some names such as `nul', `prn', and `aux' could not be
     used as filenames because they are reserved as device names.
     These are now allowable names in MySQL. They are encoded by
     appending `@@@' to the name when the server creates the
     corresponding file or directory. This occurs on all platforms for
     portability of the corresponding database object between platforms.
     (Bug#17870 (http://bugs.mysql.com/17870))

   * The bundled yaSSL library was upgraded to version 1.3.5. This
     improves handling of certain problems with SSL-related command
     options.  (Bug#17737 (http://bugs.mysql.com/17737))

   * You must now have the `DROP' privilege to drop table partitions.
     (Bug#17139 (http://bugs.mysql.com/17139))

   * Server and clients ignored the `--sysconfdir' option that was
     passed to `configure'. The directory specified by this option, if
     set, now is used as one of the standard locations in which to look
     for option files.  (Bug#15069 (http://bugs.mysql.com/15069))

   * In result set metadata, the `MYSQL_FIELD.length' value for `BIT'
     columns now is reported in number of bits. For example, the value
     for a `BIT(9)' column is 9. (Formerly, the value was related to
     number of bytes.)  (Bug#13601 (http://bugs.mysql.com/13601))

   * Added the `KEY_BLOCK_SIZE' table option and index option. This can
     be used in `CREATE TABLE', `ALTER TABLE', and `CREATE INDEX'
     statements to provide a hint to the storage engine about the size
     to use for index key blocks.  The engine is allowed to change the
     value if necessary.

   * Added the `sql_big_selects' system variable to the output of `SHOW
     VARIABLES'.

   * The `mysql_upgrade' command has been converted from a shell script
     to a C program, so it is available on non-Unix systems such as
     Windows. This program should be run for each MySQL upgrade. See
     *Note mysql-upgrade::.

   * Added the `REFERENTIAL_CONSTRAINTS' table to `INFORMATION_SCHEMA'.
     It provides information about foreign keys.

   * Added the `have_dynamic_loading' system variable that indicates
     whether the server supports dynamic loading of plugins.

   * Added `--debug' option to Instance Manager.

   * Binary distributions that include SSL support now are built using
     yaSSL when possible.

Bugs fixed:

   * *Security Fix*: A `NUL' byte within a comment in a statement
     string caused the rest of the string not to be written to the
     query log, allowing logging to be bypassed.  (Bug#17667
     (http://bugs.mysql.com/17667), CVE-2006-0903
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-0903))

   * *Security Fix*: A malicious client, using specially crafted invalid
     `COM_TABLE_DUMP' packets was able to trigger an exploitable buffer
     overflow on the server. Thanks to Stefano Di Paola
     <stefano.dipaola@wisec.it> for finding and reporting this bug.
     (CVE-2006-1518
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-1518))

   * *Security Fix*: A malicious client, using specially crafted
     invalid login or `COM_TABLE_DUMP' packets was able to read
     uninitialized memory, which potentially, though unlikely in MySQL,
     could have led to an information disclosure. (, ) Thanks to
     Stefano Di Paola <stefano.dipaola@wisec.it> for finding and
     reporting this bug.  (CVE-2006-1516
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-1516),
     CVE-2006-1517
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-1517))

   * *MySQL Cluster*: A 5.1.6 or newer server did not read local
     checkpoints recorded by any other 5.1 version, thus preventing a
     system restart following an upgrade.  (Bug#19333
     (http://bugs.mysql.com/19333))

   * *MySQL Cluster*: Concurrent `INSERT' and `ROLLBACK' statements
     from different connections could cause node failures.  (Bug#19245
     (http://bugs.mysql.com/19245))

   * *MySQL Cluster*: (Disk Data): Running an `INSERT' and a `DELETE'
     on a Disk Data table in the same transaction could cause a
     deadlock.  (Bug#19244 (http://bugs.mysql.com/19244))

   * *MySQL Cluster*: Starting `mysqld' without `--log-bin' caused DDL
     statements on `NDB' tables to time out.  (Bug#19214
     (http://bugs.mysql.com/19214))

   * *MySQL Cluster*: (NDBAPI): Passing a nonexistent index name to
     `NdbIndexScanOperation::setBound()' caused a segmentation fault.
     (Bug#19088 (http://bugs.mysql.com/19088))

   * *MySQL Cluster*: `mysql-test-run.pl' started `NDB' even for test
     cases that did not need it.  (Bug#19083
     (http://bugs.mysql.com/19083))

   * *MySQL Cluster*: Stopping multiple nodes could cause node failure
     handling not to be completed.  (Bug#19039
     (http://bugs.mysql.com/19039))

   * *MySQL Cluster*: The Cluster binlog `mysqld' accepted updates even
     though the binary log was not set up, which could lead to updates
     missing from the binary log.  (Bug#18932
     (http://bugs.mysql.com/18932))

   * *MySQL Cluster*: `mysqld' could crash when attempting an update if
     the cluster had failed previously.  (Bug#18798
     (http://bugs.mysql.com/18798))

   * *MySQL Cluster*: An `INSERT' or `UPDATE' of more than 128 bytes of
     data in a 4-replica cluster could cause data nodes to crash.
     (Bug#18622 (http://bugs.mysql.com/18622))

   * *MySQL Cluster*: (Disk Data): `CREATE LOGFILE GROUP' accepted
     values other than `NDB' or `NDBCLUSTER' in the `ENGINE' clause.
     (Bug#18604 (http://bugs.mysql.com/18604))

   * *MySQL Cluster*: (Disk Data): Omitting the required `ENGINE'
     clause from a `CREATE LOGFILE GROUP' or `CREATE TABLESPACE'
     statement caused the server to crash. An appropriate error message
     is now returned instead.  (Bug#18603 (http://bugs.mysql.com/18603))

   * *MySQL Cluster*: Queries using `ORDER BY PKN ' failed against a
     `LIST'-partitioned Cluster table having a multi-column primary
     key, where PKN represents one of the columns making up the primary
     key.  (Bug#18598 (http://bugs.mysql.com/18598))

   * *MySQL Cluster*: A simultaneous `DROP TABLE' and table update
     operation utilising a table scan could trigger a node failure.
     (Bug#18597 (http://bugs.mysql.com/18597))

   * *MySQL Cluster*: Fragment IDs were not logged correctly, causing
     `ndb_restore_log' to fail.  (Bug#18594
     (http://bugs.mysql.com/18594))

   * *MySQL Cluster*: Repeated use of the `SHOW' and `ALL STATUS'
     commands in the `ndb_mgm' client could cause the `mgmd' process to
     crash.  (Bug#18591 (http://bugs.mysql.com/18591))

   * *MySQL Cluster*: `ndbd' sometimes failed to start with the error
     `Node failure handling not completed' following a graceful restart.
     (Bug#18550 (http://bugs.mysql.com/18550))

   * *MySQL Cluster*: `ndb_restore' failed to restore a backup made
     from a 5.0 cluster to a 5.1 cluster.  (Bug#18210
     (http://bugs.mysql.com/18210))

   * *MySQL Cluster*: Adding an index to an unsigned integer column did
     not work correctly.  (Bug#18133 (http://bugs.mysql.com/18133))

   * *MySQL Cluster*: A `SELECT' from an `NDB' table with `ORDER BY
     INDEXED_COLUMN ' and a `LIMIT' clause would fail following `ALTER
     TABLE'.  (Bug#18094 (http://bugs.mysql.com/18094))

   * *MySQL Cluster*: `mysqldump' included in its output data from the
     internal `cluster' database.  (Bug#17840
     (http://bugs.mysql.com/17840))

   * *MySQL Cluster*: Backups could fail for large clusters with many
     tables, where the number of tables approached `MaxNoOfTables'.
     (Bug#17607 (http://bugs.mysql.com/17607))

   * *MySQL Cluster*: Some queries having a `WHERE' clause of the form
     `c1=val1 OR c2 LIKE 'val2'' were not evaluated correctly.
     (Bug#17421 (http://bugs.mysql.com/17421))

   * *MySQL Cluster*: (Replication): Delete and update of rows in a
     table without a primary key failed on the slave.  (Bug#17400
     (http://bugs.mysql.com/17400))

   * *MySQL Cluster*: An issue with `ndb_mgmd' prevented more than 27
     `mysqld' processes from connecting to a single cluster at one time.
     (Bug#17150 (http://bugs.mysql.com/17150))

   * *MySQL Cluster*: In a 2-node cluster with a node failure,
     restarting the node with a low value for `StartPartialTimeout'
     could cause the cluster to come up partitioned (`split-brain'
     issue).

     A similar issue could occur when the cluster was first started
     with a sufficiently low value for this parameter.  (Bug#16447
     (http://bugs.mysql.com/16447), Bug#18612
     (http://bugs.mysql.com/18612))

   * *MySQL Cluster*: Performing multiple `ALTER TABLE' operations on
     the same `NDB' table from different `mysqld' processes in the same
     cluster led to schema versioning errors when trying to access the
     table again following the restart of one of the `mysqld' processes.
     (Bug#16445 (http://bugs.mysql.com/16445))

   * *MySQL Cluster*: On systems with multiple network interfaces, data
     nodes would get `stuck' in startup phase 2 if the interface
     connecting them to the management server was working on node
     startup while the interface interconnecting the data nodes
     experienced a temporary outage.  (Bug#15695
     (http://bugs.mysql.com/15695))

   * *MySQL Cluster*: On slow networks or CPUs, the management client
     `SHOW' command could sometimes erroneously show all data nodes as
     being master nodes belonging to nodegroup 0.  (Bug#15530
     (http://bugs.mysql.com/15530))

   * *MySQL Cluster*: Unused open handlers for tables in which the
     metadata had changed were not properly closed. This could result
     in stale results from `NDB' tables following an `ALTER TABLE'
     statement.  (Bug#13228 (http://bugs.mysql.com/13228))

   * *MySQL Cluster*: Uninitialized internal variables could lead to
     unexpected results.  (Bug#11033 (http://bugs.mysql.com/11033),
     Bug#11034 (http://bugs.mysql.com/11034))

   * *MySQL Cluster*: When attempting to create an index on a `BIT' or
     `BLOB' column, `Error 743: Unsupported character set in table or
     index' was returned instead of `Error 906: Unsupported attribute
     type in index'.

   * *Cluster Replication*: *Partitioning*: Attempting to create an
     index using multiple columns on an explicitly partitioned table in
     a replicated Cluster database could cause the master `mysqld'
     process to crash.  (Bug#18284 (http://bugs.mysql.com/18284))

   * *Disk Data*: Issuing a `CREATE LOGFILE GROUP' statement during the
     drop of an `NDB' table would cause database corruption.
     (Bug#19141 (http://bugs.mysql.com/19141))

   * *Disk Data*: Concurrent table schema operations and operations on
     log file groups, tablespaces, data files, or undo files could lead
     to data node failures.  (Bug#18575 (http://bugs.mysql.com/18575))

   * *Cluster Replication*: Using the `--binlog-do-db' option caused
     problems with `CREATE TABLE' on the cluster acting as the
     replication master.  (Bug#19492 (http://bugs.mysql.com/19492))

   * *Cluster Replication*: When taking part in Cluster replication of
     tables containing `BLOB' columns, `mysqld' falsely reported a
     large memory leak in the replication buffers when there was none.
     (Bug#19247 (http://bugs.mysql.com/19247))

   * *Cluster Replication*: Trying to restore the `apply_status' table
     from a 5.0 cluster backup failed on a 5.1 server.  (Bug#18935
     (http://bugs.mysql.com/18935))

   * *Cluster Replication*: An issue with replication caused a `mysqld'
     connected to a replicated cluster to crash when entering single
     user mode.  (Bug#18535 (http://bugs.mysql.com/18535))

   * A compatibility issue with NPTL (Native POSIX Thread Library) on
     Linux could result in a deadlock with `FLUSH TABLES WITH READ
     LOCK' under some conditions.  (Bug#20048
     (http://bugs.mysql.com/20048))

   * Some outer joins were incorrectly converted to inner joins.
     (Bug#19816 (http://bugs.mysql.com/19816)) This regression was
     introduced by Bug#17146 (http://bugs.mysql.com/17146)

   * A view definition that referred to an alias in the `HAVING' clause
     could be saved in the `.frm' file with the alias replaced by the
     expression that it referred to, causing failure of subsequent
     `SELECT * FROM VIEW_NAME ' statements.  (Bug#19573
     (http://bugs.mysql.com/19573))

   * `mysql' displayed `NULL' for strings that are empty or contain
     only spaces.  (Bug#19564 (http://bugs.mysql.com/19564))

   * Selecting from a view that used `GROUP BY' on a non-constant
     temporal interval (such as `DATE(COL) + INTERVAL TIME_TO_SEC(COL)
     SECOND' could cause a server crash.  (Bug#19490
     (http://bugs.mysql.com/19490))

   * An outer join of two views that was written using `{ OJ ... }'
     syntax could cause a server crash.  (Bug#19396
     (http://bugs.mysql.com/19396))

   * An issue with file handling in the partitioning code could cause
     `mysqld' to crash when started and then stopped within a very
     short period of time.  (Bug#19313 (http://bugs.mysql.com/19313))

   * `myisamchk' and `myisam_ftdump' should allow either table names or
     `.MYI' filenames as arguments, but allowed only table names.
     (Bug#19220 (http://bugs.mysql.com/19220))

   * `InnoDB' could read a delete mark from its system tables
     incorrectly.  (Bug#19217 (http://bugs.mysql.com/19217))

   * Executing a `CREATE EVENT' statement could cause 100% CPU usage.
     (Bug#19170 (http://bugs.mysql.com/19170))

   * Eliminated some memory corruption problems that resultsd in
     `double free or corruption' errors and a server crash.  (Bug#19154
     (http://bugs.mysql.com/19154))

   * Attempting to set the default value of an `ENUM' or `SET' column to
     `NULL' caused a server crash.  (Bug#19145
     (http://bugs.mysql.com/19145))

   * Index corruption could occur in cases when `key_cache_block_size'
     was not a multiple of `myisam_block_size' (for example, with
     `key_cache_block_size=1536' and `myisam_block_size=1024').
     (Bug#19079 (http://bugs.mysql.com/19079))

   * Instance Manager now finds the version numbers, so that it works
     properly when the executable name isn't the same as what the
     Instance Manager launched (such as when wrapping a
     `libtool'-wrapped executable from the source tree).  (Bug#19059
     (http://bugs.mysql.com/19059))

   * Some fast `ALTER TABLE' operations (requiring no temporary table)
     did not work for all tables.  (Bug#19011
     (http://bugs.mysql.com/19011))

   * Successive `ALTER TABLE ... DROP PARTITION' statements on the same
     subpartitioned table could eventually cause the server to crash.
     (Bug#18962 (http://bugs.mysql.com/18962))

   * Creating a table in an `InnoDB' database with a column name that
     matched the name of an internal `InnoDB' column (including
     `DB_ROW_ID', `DB_TRX_ID', `DB_ROLL_PTR' and `DB_MIX_ID') would
     cause a crash. MySQL now returns Error 1005 `Cannot create table'
     with `errno' set to -1.  (Bug#18934 (http://bugs.mysql.com/18934))

   * The parser leaked memory when its stack needed to be extended.
     (Bug#18930 (http://bugs.mysql.com/18930))

   * MySQL would not compile on Linux distributions that use the
     `tinfo' library.  (Bug#18912 (http://bugs.mysql.com/18912))

   * The server attempted to flush uninitialized log tables during
     `SIGHUP' processing, causing a crash.  (Bug#18848
     (http://bugs.mysql.com/18848))

   * For a reference to a non-existent stored function in a stored
     routine that had a `CONTINUE' handler, the server continued as
     though a useful result had been returned, possibly resulting in a
     server crash.  (Bug#18787 (http://bugs.mysql.com/18787))

   * For single-`SELECT' union constructs of the form (SELECT ... ORDER
     BY ORDER_LIST1 [LIMIT N]) ORDER BY ORDER_LIST2, the `ORDER BY'
     lists were concatenated and the `LIMIT' clause was ignored.
     (Bug#18767 (http://bugs.mysql.com/18767))

   * Inserts failed with duplicate key errors on a table partitioned
     using an `AUTO_INCREMENT' column for the partitioning key.
     (Bug#18753 (http://bugs.mysql.com/18753), Bug#18552
     (http://bugs.mysql.com/18552))

   * It was possible to create a `RANGE'-partitioned table with a
     partition defined using the clause `VALUES LESS THAN (NULL)', even
     though such a partition could never contain any values whatsoever.
     (Bug#18752 (http://bugs.mysql.com/18752))

   * Delimited identifiers for partitions were not being treated the
     same as delimited identifiers for other database objects (such as
     tables and columns) with regard to allowed characters.  (Bug#18750
     (http://bugs.mysql.com/18750))

   * `CREATE VIEW' statements would not be replicated to the slave if
     the `--replicate-wild-ignore-table' rule was enabled.  (Bug#18715
     (http://bugs.mysql.com/18715))

   * Conversion of a number to a `CHAR UNICODE' string returned an
     invalid result.  (Bug#18691 (http://bugs.mysql.com/18691))

   * If the second or third argument to `BETWEEN' was a constant
     expression such as `'2005-09-01 - INTERVAL 6 MONTH' and the other
     two arguments were columns, `BETWEEN' was evaluated incorrectly.
     (Bug#18618 (http://bugs.mysql.com/18618))

   * `LOAD DATA FROM MASTER' would fail when trying to load the
     `INFORMATION_SCHEMA' database from the master, because the
     `INFORMATION_SCHEMA' system database would already exist on the
     slave.  (Bug#18607 (http://bugs.mysql.com/18607))

   * Running an `ALTER TABLE' on a partitioned table simultaneously
     experiencing a high number of concurrent DML statements could
     crash the server.  (Bug#18572 (http://bugs.mysql.com/18572))

   * A `LOCK TABLES' statement that failed could cause `MyISAM' not to
     update table statistics properly, causing a subsequent `CHECK
     TABLE' to report table corruption.  (Bug#18544
     (http://bugs.mysql.com/18544))

   * `mysqltest' incorrectly interpreted some `ER_XXX' error names
     given in the `error' command.  (Bug#18495
     (http://bugs.mysql.com/18495))

   * `InnoDB': `ALTER TABLE' to add or drop a foreign key for an
     `InnoDB' table had no effect.  (Bug#18477
     (http://bugs.mysql.com/18477))

   * `InnoDB' did not use a consistent read for `CREATE ... SELECT' when
     `innodb_locks_unsafe_for_binlog' was set.  (Bug#18350
     (http://bugs.mysql.com/18350))

   * `DROP DATABASE' did not drop stored routines associated with the
     database if the database name was longer than 21 characters.
     (Bug#18344 (http://bugs.mysql.com/18344))

   * A query on a table partitioned or subpartitioned by `HASH' did not
     display all results when using a `WHERE' condition involving a
     column used in the hashing expression.  (Bug#18329
     (http://bugs.mysql.com/18329), Bug#18423
     (http://bugs.mysql.com/18423))

   * In `mysqltest', `--sleep=0' had no effect. Now it correctly causes
     `sleep' commands in test case files to sleep for 0 seconds.
     (Bug#18312 (http://bugs.mysql.com/18312))

   * `ExtractValue' function did not return character data within
     `<![CDATA[]]>' as expected.  (Bug#18285
     (http://bugs.mysql.com/18285))

   * A recent change caused the `mysql' client not to display `NULL'
     values correctly and to display numeric columns left-justified
     rather than right-justified. The problems have been corrected.
     (Bug#18265 (http://bugs.mysql.com/18265))

   * Updates to a `MEMORY' table caused the size of `BTREE' indexes for
     the table to increase.  (Bug#18160 (http://bugs.mysql.com/18160))

   * A failed `ALTER TABLE' operation could fail to clean up a
     temporary `.frm' file.  (Bug#18129 (http://bugs.mysql.com/18129))

   * Event-creation statements enclosed in multi-line comments using
     `/*!VERSION_NUMBER ...  */' syntax were not parsed correctly.
     (Bug#18078 (http://bugs.mysql.com/18078))

   * `SELECT DISTINCT' queries sometimes returned only the last row.
     (Bug#18068 (http://bugs.mysql.com/18068))

   * `InnoDB': A `DELETE' followed by an `INSERT' and then by an
     `UPDATE' on a partitioned `InnoDB' table caused subsequent queries
     to return incorrect results.  (Bug#17992
     (http://bugs.mysql.com/17992))

   * It was possible to use trailing spaces in the names of partitions
     and subpartitions. Attempting to do so now raises the error
     `Incorrect partition name'.  (Bug#17973
     (http://bugs.mysql.com/17973))

   * `LIKE' searches failed on a `CHAR' column used as the partitioning
     column of a table partitioned by `KEY'.  (Bug#17946
     (http://bugs.mysql.com/17946))

   * Executing `SELECT' on a large table that had been compressed
     within `myisampack' could cause a crash.  (Bug#17917
     (http://bugs.mysql.com/17917))

   * The `sql_big_selects' system variable was not displayed by `SHOW
     VARIABLES'.  (Bug#17849 (http://bugs.mysql.com/17849))

   * `REPAIR TABLE' did not restore the length for packed keys in
     tables created under MySQL 4.x, which caused them to appear
     corrupt to `CHECK TABLE' but not to `REPAIR TABLE'.  (Bug#17810
     (http://bugs.mysql.com/17810))

   * A range access optimizer heuristic was invalid, causing some
     queries to be much slower in MySQL 5.0 than in 4.0.  (Bug#17379
     (http://bugs.mysql.com/17379), Bug#18940
     (http://bugs.mysql.com/18940))

   * Logging to the `mysql.general_log' and `mysql.slow_log' tables did
     not work for Windows builds because the `CSV' storage engine was
     unavailable. The `CSV' engine now is enabled in Windows builds.
     (Bug#17368 (http://bugs.mysql.com/17368))

   * Updating a field value when also requesting a lock with
     `GET_LOCK()' would cause slave servers in a replication
     environment to terminate.  (Bug#17284
     (http://bugs.mysql.com/17284))

   * The binary log would create an incorrect `DROP' query when
     creating temporary tables during replication.  (Bug#17263
     (http://bugs.mysql.com/17263))

   * If the `WHERE' condition of a query contained an `OR'-ed `FALSE'
     term, the set of tables whose rows cannot serve for
     null-complements in outer joins was determined incorrectly. This
     resulted in blocking possible conversions of outer joins into
     joins by the optimizer for such queries.  (Bug#17164
     (http://bugs.mysql.com/17164))

   * Casting a string to `DECIMAL' worked, but casting a trimmed string
     (using `LTRIM()' or `RTRIM()') resulted in loss of decimal digits.
     (Bug#17043 (http://bugs.mysql.com/17043))

   * `MyISAM' table deadlock was possible if one thread issued a `LOCK
     TABLES' request for write locks and then an administrative
     statement such as `OPTIMIZE TABLE', if between the two statements
     another client meanwhile issued a multiple-table `SELECT' for some
     of the locked tables.  (Bug#16986 (http://bugs.mysql.com/16986))

   * `ALTER TABLE ... REBUILD PARTITION' returned an inaccurate error
     message.  (Bug#16819 (http://bugs.mysql.com/16819))

   * Use of `--default-storage-engine=innodb' resulted in an error with
     the server reporting that `InnoDB' was an unknown table type.
     (Bug#16691 (http://bugs.mysql.com/16691))

   * `MySQL-shared-compat-5.1.9-0.i386.rpm' incorrectly depended on
     `glibc' 2.3 and could not be installed on a `glibc' 2.2 system.
     (Bug#16539 (http://bugs.mysql.com/16539))

   * The presence of multiple equalities in a condition after reading a
     constant table could cause the optimizer not to use an index.
     This resulted in certain queries being much slower than in MySQL
     4.1.  (Bug#16504 (http://bugs.mysql.com/16504))

   * Within a trigger, `CONNECTION_ID()' did not return the connection
     ID of the thread that caused the trigger to be activated.
     (Bug#16461 (http://bugs.mysql.com/16461))

   * The XPath `string-length()' function was not implemented for use
     with `ExtractValue()'.  (Bug#16319 (http://bugs.mysql.com/16319))

   * The `ExtractValue()' function failed with a syntax error when the
     XPath expression used special characters such as `N~' (`N-tilde').
     (Bug#16233 (http://bugs.mysql.com/16233))

   * The `sql_notes' and `sql_warnings' system variables were not always
     displayed correctly by `SHOW VARIABLES' (for example, they were
     displayed as `ON' after being set to `OFF').  (Bug#16195
     (http://bugs.mysql.com/16195))

   * If the first argument to `BETWEEN' was a `DATE' or `TIME' column
     of a view and the other arguments were constants, `BETWEEN' did not
     perform conversion of the constants to the appropriate temporary
     type, resulting in incorrect evaluation.  (Bug#16069
     (http://bugs.mysql.com/16069))

   * After calling `FLUSH STATUS', the `max_used_connections' variable
     did not increment for existing connections and connections which
     use the thread cache.  (Bug#15933 (http://bugs.mysql.com/15933))

   * `DELETE' and `UPDATE' statements that used large `NOT IN
     (VALUE_LIST)' clauses could use large amounts of memory.
     (Bug#15872 (http://bugs.mysql.com/15872))

   * `InnoDB' failure to release an adaptive hash index latch could
     cause a server crash if the query cache was enabled.  (Bug#15758
     (http://bugs.mysql.com/15758))

   * `LAST_INSERT_ID()' in a stored function or trigger returned zero. .
     (Bug#15728 (http://bugs.mysql.com/15728))

   * The `system_time_zone' and `version_*' system variables could not
     be accessed via `SELECT @@VAR_NAME' syntax.  (Bug#15684
     (http://bugs.mysql.com/15684), Bug#12792
     (http://bugs.mysql.com/12792))

   * If the server were built without partition support, it was
     possible to run partitioning-related statements with no errors or
     warnings, even though these statements would have no effect.  Now
     such statements are disallowed unless the server has been compiled
     using the `--with-partition' option.  (Bug#15561
     (http://bugs.mysql.com/15561))

   * Use of `CONVERT_TZ()' in a view definition could result in
     spurious syntax or access errors.  (Bug#15153
     (http://bugs.mysql.com/15153))

   * Prevent recursive views caused by using `RENAME TABLE' on a view
     after creating it.  (Bug#14308 (http://bugs.mysql.com/14308))

   * Some queries were slower in 5.0 than in 4.1 because some 4.1
     cost-evaluation code had not been merged into 5.0.  (Bug#14292
     (http://bugs.mysql.com/14292))

   * Avoid trying to include `<asm/atomic.h>' when it doesn't work in
     C++ code.  (Bug#13621 (http://bugs.mysql.com/13621))

   * Running `myisampack' followed by `myisamchk' with the `--unpack'
     option would corrupt the `auto_increment' key.  (Bug#12633
     (http://bugs.mysql.com/12633))

   * Use of `CONVERT_TZ()' in a stored function or trigger (or in a
     stored procedure called from a stored function or trigger) caused
     an error.  (Bug#11081 (http://bugs.mysql.com/11081))

   * When `myisamchk' needed to rebuild a table, `AUTO_INCREMENT'
     information was lost.  (Bug#10405 (http://bugs.mysql.com/10405))


File: manual.info,  Node: news-5-1-9,  Next: news-5-1-8,  Prev: news-5-1-10,  Up: news-5-1-x

C.1.21 Changes in MySQL 5.1.9 (12 April 2006)
---------------------------------------------

This is a new Beta development release, fixing recently discovered bugs.

*Note*:

This Beta release, as any other pre-production release, should not be
installed on _production_ level systems or systems with critical data.
It is good practice to back up your data before installing any new
version of software.  Although MySQL has worked very hard to ensure a
high level of quality, protect your data by making a backup as you
would for any software beta release. Please refer to our bug database at
`http://bugs.mysql.com/' for more details about the individual bugs
fixed in this version.

This section documents all changes and bug fixes that have been applied
since the last official MySQL release. If you would like to receive
more fine-grained and personalized _update alerts_ about fixes that are
relevant to the version and features you use, please consider
subscribing to _MySQL Enterprise_ (a commercial MySQL offering). For
more details please see `http://www.mysql.com/products/enterprise'.

Functionality added or changed:

   * *MySQL Cluster*: The `NDB' storage engine now supports `CREATE
     TABLE' statements of arbitrary length.  (Previously, `CREATE
     TABLE' statements for MySQL Cluster tables could contain a maximum
     of 4096 characters only.)  (Bug#17813
     (http://bugs.mysql.com/17813))

   * *MySQL Cluster*: Added the `--nowait-nodes' startup option for
     `ndbd', making it possible to skip specified nodes without waiting
     for them to start when starting the cluster. See *Note
     mysql-cluster-ndbd-command-options::.

   * `mysqld_safe' no longer checks for a `mysqld-max' binary. Instead,
     `mysqld_safe' nows checks only for the standard `mysqld' server
     unless another server binary is specified explicitly via
     `--mysqld' or `--mysqld-version'. If you previously relied on the
     implicit invocation of `mysqld-max', you should use an appropriate
     option now.  (Bug#17861 (http://bugs.mysql.com/17861))

   * For partitioned tables, the output of `SHOW TABLE STATUS' now
     shows in the `Engine' column the name of the storage engine used
     by all partitions for the table; in the `Create_options' column,
     the output now shows `partitioned' for a partitioned table. This
     change also affects the values shown in the corresponding columns
     of the `INFORMATION_SCHEMA.TABLES' table.  (Bug#17631
     (http://bugs.mysql.com/17631))

   * `SHOW PLUGIN' was renamed to `SHOW PLUGINS'. `SHOW PLUGIN' now is
     deprecated and generates a warning.  (Bug#17112
     (http://bugs.mysql.com/17112))

   * Large file support was re-enabled for the MySQL server binary for
     the AIX 5.2 platform.  (Bug#13571 (http://bugs.mysql.com/13571))

   * Binary MySQL distributions now include a `mysqld-max' server, in
     addition to the usual `mysqld' optimized server and the
     `mysqld-debug' debugging server.

Bugs fixed:

   * *Security Fix*: Invalid arguments to `DATE_FORMAT()' caused a
     server crash. Thanks to Jean-David Maillefer for discovering and
     reporting this problem to the Debian project and to Christian
     Hammers from the Debian Team for notifying us of it.  (Bug#20729
     (http://bugs.mysql.com/20729), CVE-2006-3469
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-3469))

   * *Partitioning*: *MySQL Cluster*: `BLOB' columns did not work
     correctly with user-partitioned `NDB' tables.  (Bug#16796
     (http://bugs.mysql.com/16796))

   * *MySQL Cluster*: An uninitialized internal variable could lead to
     unexpected results.  (Bug#18831 (http://bugs.mysql.com/18831))

   * *MySQL Cluster*: `TRUNCATE' did not reset the `AUTO_INCREMENT'
     counter for `MyISAM' tables when issued inside a stored procedure.

     *Note*:

     This bug did not affect `InnoDB' tables.

     In addition, `TRUNCATE' does not reset the `AUTO_INCREMENT'
     counter for `NDB' tables regardless of when it is called.

     (Bug#14945 (http://bugs.mysql.com/14945)) See also Bug#18864
     (http://bugs.mysql.com/18864)

   * For full-text searches in boolean mode, and when a full-text
     parser plugin was used, a `MYSQL_FTPARSER_PARAM::ftparser_state'
     could have been corrupted by recursive calls to the plugin.
     (Bug#18836 (http://bugs.mysql.com/18836))

   * `mysql_reconnect()' sent a `SET NAMES' statement to the server,
     even for pre-4.1 servers that do not understand the statement.
     (Bug#18830 (http://bugs.mysql.com/18830))

   * A query against a partitioned table using `WHERE COL IS NULL'
     could produce incorrect results given the following conditions:

        * The table had partitions and subpartitions

        * The partitioning function depended on a single column COL of
          one of the MySQL integer types

        * The partitioning function was not monotonically increasing

     The same issue could cause the server to crash when run in debug
     mode.  (Bug#18659 (http://bugs.mysql.com/18659))

   * Partition pruning did not work properly for some kinds of
     partitioning and subpartitioning, with certain `WHERE' clauses.
     (Partitions and subpartitions that should have been marked as used
     were not so marked.) The error could manifest as incorrect content
     in `EXPLAIN PARTITIONS' output as well as missing rows in the
     results of affected queries.  (Bug#18558
     (http://bugs.mysql.com/18558))

   * Building the server using `--with-example-storage-engine' failed
     to enable the `EXAMPLE' storage engine in the server.  (Bug#18464
     (http://bugs.mysql.com/18464))

   * If `InnoDB' encountered a `HA_ERR_LOCK_TABLE_FULL' error and
     rolled back a transaction, the transaction was still written to
     the binary log.  (Bug#18283 (http://bugs.mysql.com/18283))

   * Complex queries with nested joins could cause a server crash.
     (Bug#18279 (http://bugs.mysql.com/18279))

   * `COUNT(*)' on a `MyISAM' table could return different results for
     the base table and a view on the base table.  (Bug#18237
     (http://bugs.mysql.com/18237))

   * `EXTRACT(QUARTER FROM DATE)' returned unexpected results.
     (Bug#18100 (http://bugs.mysql.com/18100))

   * Queries using `WHERE ... IS NULL' returned incorrect results from
     partitioned tables.  (Bug#18070 (http://bugs.mysql.com/18070))

   * Partition pruning did not perform correctly with partitions on
     `NULL', and could potentially crash the server.  (Bug#18053
     (http://bugs.mysql.com/18053))

   * `MEDIUMINT' columns were not handled in the same way as other
     column types by partition pruning.

     Partition pruning would sometimes use inappropriate columns in
     preforming queries.

     Both of these issues were rectified as part of the same bugfix.
     (Bug#18025 (http://bugs.mysql.com/18025))

   * For tables created in a MySQL 4.1 installation upgraded to MySQL
     5.0 and up, multiple-table updates could update only the first
     matching row.  (Bug#16281 (http://bugs.mysql.com/16281))

   * For `mysql.server', if the `basedir' option was specified after
     `datadir' in an option file, the setting for `datadir' was ignored
     and assumed to be located under `basedir'.  (Bug#16240
     (http://bugs.mysql.com/16240))

   * Triggers created in one version of the server could not be dropped
     after upgrading to a newer version.  (Bug#15921
     (http://bugs.mysql.com/15921))

   * `CAST(DOUBLE AS SIGNED INT)' for large DOUBLE values outside the
     signed integer range truncated the result to be within range, but
     the result sometimes had the wrong sign, and no warning was
     generated.  (Bug#15098 (http://bugs.mysql.com/15098))

   * Quoted values could not be used for partition option values.
     (Bug#13520 (http://bugs.mysql.com/13520))

   * Delimited identifiers could not be used in defining partitions.
     (Bug#13433 (http://bugs.mysql.com/13433))

   * `mysql_config' returned incorrect libraries on `x86_64' systems.
     (Bug#13158 (http://bugs.mysql.com/13158))

   * The server was always built as though
     `--with-extra-charsets=complex' had been specified.  (Bug#12076
     (http://bugs.mysql.com/12076))

   * The table had partitions and subpartitions

   * The partitioning function was not monotonically increasing

   * The partitioning function depended on a single column COL of one
     of the MySQL integer types


File: manual.info,  Node: news-5-1-8,  Next: news-5-1-7,  Prev: news-5-1-9,  Up: news-5-1-x

C.1.22 Changes in MySQL 5.1.8 (Not released)
--------------------------------------------

*Note*:

This was an internal release only, and no binaries were published.

Functionality added or changed:

   * *Cluster Replication*: *Incompatible Change*: The
     `cluster_replication' database has been renamed to `cluster'. This
     will effect replication between MySQL Clusters where one cluster
     is running MySQL 5.1.8 or later, and the other is running MySQL
     5.1.7 or earlier. See *Note mysql-cluster-replication::, and
     especially *Note mysql-cluster-replication-schema::.

   * *Incompatible Change*: The semantics of `ALTER TABLE T ENGINE=X;'
     for partitioned tables is changed, and now means that the storage
     engine used for table T is changed to X.

     The previous statement formerly (prior to MySQL 5.1.8) meant that
     all partitioning was removed from the table. In order to remove
     the partitioning of a table, the syntax `ALTER TABLE T REMOVE
     PARTITIONING;' is introduced. The `REMOVE PARTITIONING' option can
     be used in combination with existing `ALTER TABLE' options such as
     those employed for adding or dropping columns or indexes.
     (Bug#17754 (http://bugs.mysql.com/17754))

   * *Incompatible Change*: For purposes of determining placement,
     `RANGE' partitioning now treats `NULL' as less than any other
     value. (Formerly, `NULL' was treated as equal to zero.) See *Note
     partitioning-handling-nulls::.  (Bug#15447
     (http://bugs.mysql.com/15447))

   * *MySQL Cluster*: The stability of `CREATE' and `DROP' operations
     on `NDB' tables containing `BLOB' columns has been improved.
     (Bug#17761 (http://bugs.mysql.com/17761))

   * *MySQL Cluster*: The `NDBCLUSTER' storage engine now supports
     `INSERT IGNORE' and `REPLACE' statements. Previously, these
     statements failed with an error.  (Bug#17431
     (http://bugs.mysql.com/17431))

   * *Disk Data*: You can now have only one log file group at any one
     time. See *Note create-logfile-group::.  (Bug#16386
     (http://bugs.mysql.com/16386))

   * Builds for Windows, Linux, and Unix (except AIX) platforms now
     have SSL support enabled, in the server as well as in the client
     libraries. Because part of the SSL code is written in C++, this
     does introduce dependencies on the system's C++ runtime libraries
     in several cases, depending on compiler specifics.  (Bug#18195
     (http://bugs.mysql.com/18195))

   * Partition pruning was made more stable, particularly in cases
     involving queries using tests for `NULL' values in the `WHERE'
     clause against subpartitioned tables which were partitioned by
     `LIST( SOME_FUNCTION(COL1, ... ,COLN) )'.  (Bug#17891
     (http://bugs.mysql.com/17891))

   * The output of `SHOW CREATE EVENT' no longer qualifies the event
     name with the name of the schem to which the event belongs.
     (Bug#17714 (http://bugs.mysql.com/17714))

   * The deprecated constructs in the following table now generate
     warnings. You should not employ them in new applications, as they
     are likely to be removed in a future version of MySQL. Use the
     equivalents shown in the table's second column instead. For the
     same reason, existing applications that depend on the deprecated
     constructs should be converted to make use of the current
     equivalents as soon as possible.

     *Deprecated / Obsolete*:           *Current / Preferred*:
     `@@table_type'                     `@@storage_engine'
     `@@log_bin_trust_routine_creators' `@@log_bin_trust_function_creators'
     `TIMESTAMP(N)'                     See *Note
                                        date-and-time-functions::.
     `TYPE='                            `ENGINE='
     `BACKUP TABLE'                     `mysqldump', `mysqlhotcopy', or
                                        MySQL Administrator
     `RESTORE TABLE', `LOAD TABLE FROM  `mysqldump', `mysql', or MySQL
     MASTER'                            Administrator
     `SHOW TABLE TYPES'                 `SHOW [STORAGE] ENGINES'
     `SHOW INNODB STATUS'               `SHOW ENGINE INNODB STATUS'
     `SHOW MUTEX STATUS'                `SHOW ENGINE INNODB MUTEX'
     `SHOW BDB LOGS', `SHOW LOGS'       `SHOW ENGINE BDB LOGS'

     `SHOW BDB LOGS' and `SHOW LOGS' are removed as of MySQL 5.1.12,
     and the other deprecated items shown in the table are removed as
     of MySQL 5.2.5.

     *Important*:

     `TYPE' vs `ENGINE'

     In order not to break legacy applications, support for `TYPE =
     ENGINE_NAME ' -- deprecated since MySQL 4.0 -- has been restored,
     but now generates a warning.

     _Beginning with MySQL 5.2.5, `TYPE = ENGINE_NAME' will no longer
     be available and will produce a syntax error_.

     _You should not use `TYPE' in any new applications, and you should
     immediately begin conversion of existing applications to use the
     `ENGINE = ENGINE_NAME' syntax instead_.

     (Bug#17501 (http://bugs.mysql.com/17501))

   * Temporary tables may no longer be partitioned.  (Bug#17497
     (http://bugs.mysql.com/17497))

   * More specific error messages are now given when attempting to
     create an excessive number of partitions or subpartitions.
     (Previously, no distinction was made between an excessive number
     of partitions and an excessive number of subpartitions.)
     (Bug#17393 (http://bugs.mysql.com/17393))

   * Added the `--events' option to `mysqldump' to enable events to be
     included in the dump output.  (Bug#16853
     (http://bugs.mysql.com/16853))

   * For an event having no `STARTS' time specified when it was
     created, the `mysql.event' table's `start' column now displays the
     creation time rather than `NULL'.

     In addition, both the `SHOW EVENTS' statement's `Starts' column
     and the `STARTS' column of the `INFORMATION_SCHEMA.EVENTS' table
     are now empty rather than `NULL' when `STARTS' was not used in the
     `CREATE EVENT' statement.  (Bug#16537
     (http://bugs.mysql.com/16537))

   * Event names are now case-insenstive. That is (for example), you
     cannot have events with the names `Myevent' and `MyEvent'
     belonging to the same database and definer.  (Bug#16415
     (http://bugs.mysql.com/16415))

   * Description of the `EVENT' privilege has been changed to `To
     create, alter, drop, and execute events'.  (Bug#16412
     (http://bugs.mysql.com/16412))

   * `MICROSECOND' intervals are no longer allowed for events.
     (Bug#16411 (http://bugs.mysql.com/16411))

   * Events no longer support times past the end of the Unix epoch.
     (Formerly, such dates were interpreted as being at the beginning
     of the Unix epoch.)  (Bug#16396 (http://bugs.mysql.com/16396))

   * The XPath `last()' function is now implemented for use with
     `ExtractValue()'.  (Bug#16318 (http://bugs.mysql.com/16318))

   * The `ExtractValue()' function with `contains()' now uses the SQL
     collation in making comparisons. Perviously, comparisons were
     always binary (that is, case-sensitive).  (Bug#16316
     (http://bugs.mysql.com/16316))

   * Triggers from older servers that included no `DEFINER' clause in
     the trigger definition now execute with the privileges of the
     invoker (which on the slave is the slave SQL thread). Previously,
     replication slaves could not replicate such triggers.  (Bug#16266
     (http://bugs.mysql.com/16266))

   * Names of subpartitions must now be unique for an entire table, and
     not merely within the same partition.  (Bug#15408
     (http://bugs.mysql.com/15408))

   * Added the `--sysdate-is-now' option to `mysqld' to enable
     `SYSDATE()' to be treated as an alias for `NOW()'. See *Note
     date-and-time-functions::.  (Bug#15101
     (http://bugs.mysql.com/15101))

   * `mysqldump' now surrounds the `DEFINER', `SQL SECURITY DEFINER'
     and `WITH CHECK OPTION' clauses of a `CREATE VIEW' statement with
     "not in version" comments to prevent errors in earlier versions of
     MySQL.  (Bug#14871 (http://bugs.mysql.com/14871))

   * The `mysql_ping' function will now retry if the `reconnect' flag
     is set and error `CR_SERVER_LOST' is encountered during the first
     attempt to ping the server.  (Bug#14057
     (http://bugs.mysql.com/14057))

   * The `mysqltest' utility now converts all `CR/LF' combinations to
     `LF' to allow test cases intended for Windows to work properly on
     UNIX-like systems.  (Bug#13809 (http://bugs.mysql.com/13809))

   * The output from `SHOW CREATE TABLE' is more consistent about using
     uppercase for keywords. Data types still are in lowercase.
     (Bug#10460 (http://bugs.mysql.com/10460))

   * The client API now attempts to reconnect using TCP/IP if the
     `reconnect' flag is set, as is the case with sockets.  (Bug#2845
     (http://bugs.mysql.com/2845))

   * The `binlog_format' system variable now can be set to a third
     format, `MIXED', as described in *Note replication-formats::.

   * The syntax for `CREATE PROCEDURE' and `CREATE FUNCTION' statements
     now includes a `DEFINER' clause. The `DEFINER' value specifies the
     security context to be used when checking access privileges at
     routine invocation time if the routine has the `SQL SECURITY
     DEFINER' characteristic. See *Note create-procedure::, for more
     information.

     When `mysqldump' is invoked with the `--routines' option, it now
     dumps the `DEFINER' value for stored routines.

   * The `binlog_format' system variable now is dynamic and can be
     changed at runtime, as described in *Note replication-formats::.

   * A slave server may now switch the replication format
     automatically. This happens when the server is running in either
     `STATEMENT' or `MIXED' format and encounters a row in the binary
     log that is written in `ROW' logging format. In that case, the
     slave switches to row-based replication temporarily for that event,
     and switches back to the previous format afterwards.

Bugs fixed:

   * *Partitioning*: *MySQL Cluster*: Trying to insert a value into a
     nonexistent `LIST' partition of an `NDB' table would cause the
     server to crash.

     *Note*:

     Beginning with MySQL 5.1.12, user-defined partitioning types other
     than `KEY' or `LINEAR KEY' were disabled for `NDB' tables.

     (Bug#17763 (http://bugs.mysql.com/17763))

   * *Partitioning*: *MySQL Cluster*: A repeated `SELECT' on a
     partitioned table that used the `NDB' storage engine could cause
     the server to crash.  (Bug#17390 (http://bugs.mysql.com/17390))

   * *MySQL Cluster*: Attempting to restart a node with dropped events
     still pending would fail.  (Bug#18491
     (http://bugs.mysql.com/18491))

   * *MySQL Cluster*: Two `mysqld' processes starting at the same time
     could cause a race condition.  (Bug#18472
     (http://bugs.mysql.com/18472))

   * *MySQL Cluster*: A timeout in the handling of an `ABORT' condition
     with more that 32 operations could yield a node failure.
     (Bug#18414 (http://bugs.mysql.com/18414))

   * *MySQL Cluster*: Two `mysqld' processes did not synchronise `DROP
     TABLE' binary log events correctly.  (Bug#18395
     (http://bugs.mysql.com/18395))

   * *MySQL Cluster*: A node restart immediately following a `CREATE
     TABLE' would fail.

     *Important*:

     This fix supports 2-node Clusters only.

     (Bug#18385 (http://bugs.mysql.com/18385))

   * *MySQL Cluster*: In event of a node failure during a rollback, a
     `false' lock could be established on the backup for that node,
     which lock could not be removed without restarting the node.
     (Bug#18352 (http://bugs.mysql.com/18352))

   * *MySQL Cluster*: When multiple node restarts were attempted
     without allowing each restart to complete, the error message
     returned was `Array index out of bounds' rather than `Too many
     crashed replicas'.  (Bug#18349 (http://bugs.mysql.com/18349))

   * *MySQL Cluster*: The cluster created a crashed replica of a table
     having an ordered index -- or when logging was not enabled, of a
     table having a table or unique index -- leading to a crash of the
     cluster following 8 successive restarts.  (Bug#18298
     (http://bugs.mysql.com/18298))

   * *MySQL Cluster*: Issuing a `DROP LOGFILE GROUP' statement would
     cause `ndbd' processes to crash if MySQL had been compiled with
     `gcc4'.  (Bug#18295 (http://bugs.mysql.com/18295))

   * *MySQL Cluster*: `auto_increment' values were not propagated
     correctly in statement-based replication.  (Bug#18208
     (http://bugs.mysql.com/18208))

   * *MySQL Cluster*: When replacing a failed master node, the
     replacement node could cause the cluster to crash from a buffer
     overflow if it had an excessively large amount of data to write to
     the cluster log.  (Bug#18118 (http://bugs.mysql.com/18118))

   * *MySQL Cluster*: Memory was mistakenly freed for `NdbRecAttr'
     objects during addition of an index while replicating the cluster,
     which could cause `mysqld' to crash.  (Bug#18106
     (http://bugs.mysql.com/18106))

   * *MySQL Cluster*: Insufficient `StringBuffer' memory when
     attempting to create a trigger caused the server to crash.
     (Bug#18101 (http://bugs.mysql.com/18101))

   * *MySQL Cluster*: Variable-length columns used as primary keys were
     not handled correctly.  (Bug#18075 (http://bugs.mysql.com/18075))

   * *MySQL Cluster*: Row-based replication could fail with tables using
     `VARCHAR' columns for primary keys and having `BLOB' columns.
     (Bug#18067 (http://bugs.mysql.com/18067))

   * *MySQL Cluster*: `CREATE UNIQUE INDEX' on a column containing
     non-unique data could cause one or more `ndbd' nodes to hang or
     crash.  (Bug#18040 (http://bugs.mysql.com/18040))

   * *MySQL Cluster*: Node recovery of tables with `VARCHAR' columns
     using character sets was inconsistent, which could cause a number
     of issues, including the data nodes failing to restart and `ALTER
     TABLE' statements to hang.  (Bug#18026
     (http://bugs.mysql.com/18026))

   * *MySQL Cluster*: A `SELECT ... ORDER BY' query on an explicitly
     partitioned Cluster table with no explicit indexes would crash the
     server.  (Bug#17899 (http://bugs.mysql.com/17899))

   * *MySQL Cluster*: `ALTER TABLE ... ADD INDEX' failed with `ERROR
     756: Index on disk column is not supported' when run against a
     Disk Data table having a primary key.  (Bug#17888
     (http://bugs.mysql.com/17888))

   * *MySQL Cluster*: In some cases, a single `ndbd' node failed
     following a system restart.  (Bug#17854
     (http://bugs.mysql.com/17854))

   * *MySQL Cluster*: (Replication): The binary log on the secondary
     master was not being set up correctly following a table rename.
     (Bug#17838 (http://bugs.mysql.com/17838))

   * *MySQL Cluster*: A simultaneous `RENAME' of several tables was
     logged multiple times.  (Bug#17827 (http://bugs.mysql.com/17827))

   * *MySQL Cluster*: Trying to perform a `DELETE' from an `NDB' table
     following a `LOCK TABLES' caused the `ndbd' processes to hang.
     (Bug#17812 (http://bugs.mysql.com/17812))

   * *MySQL Cluster*: Trying to update very large partitioned tables
     using the `NDB' storage engine sometimes caused the server to
     crash.  (Bug#17806 (http://bugs.mysql.com/17806), Bug#16385
     (http://bugs.mysql.com/16385))

   * *MySQL Cluster*: Using `ALTER TABLE ... ADD PARTITION' on a table
     partitioned by `LIST' would cause the client to hang.  (Bug#17701
     (http://bugs.mysql.com/17701))

   * *MySQL Cluster*: With a single replica, transactions waiting in
     the log synchronisation queue were not being restarted, causing
     them to be aborted.  (Bug#17536 (http://bugs.mysql.com/17536))

   * *MySQL Cluster*: `ALTER TABLE' on a partitioned `NDB' table could
     cause the server to crash.  (Bug#17499
     (http://bugs.mysql.com/17499))

   * *MySQL Cluster*: `DELETE' operations on `NDB' tables could cause
     memory leaks.  (Bug#16874 (http://bugs.mysql.com/16874))

   * *MySQL Cluster*: Some query cache statistics were not always
     correctly reported for Cluster tables.  (Bug#16795
     (http://bugs.mysql.com/16795))

   * *MySQL Cluster*: Restarting nodes were allowed to start and join
     the cluster too early.  (Bug#16772 (http://bugs.mysql.com/16772))

   * *MySQL Cluster*: `UNDO_BUFFER_SIZE' was limited to 17 MB.
     (Bug#16657 (http://bugs.mysql.com/16657), Bug#17890
     (http://bugs.mysql.com/17890))

   * *MySQL Cluster*: Inserting and deleting `BLOB' column values while
     a backup was in process could cause data nodes to shut down.
     (Bug#14028 (http://bugs.mysql.com/14028))

   * *Disk Data*: `CREATE UNIQUE INDEX' failed with `Error 4243: Index
     not found'.  (Bug#18039 (http://bugs.mysql.com/18039))

   * *Disk Data*: It was not possible to create more than 9 tablespaces.
     (Bug#16913 (http://bugs.mysql.com/16913))

   * Replication of data stored in a partitioned table would cause
     slave servers to issue a assertion and terminate.  (Bug#18436
     (http://bugs.mysql.com/18436))

   * A `SELECT ... ORDER BY ...' from a view defined using a function
     could crash the server. An example of such a view is `CREATE VIEW
     v1 AS SELECT SQRT(c1) FROM t1'.  (Bug#18386
     (http://bugs.mysql.com/18386))

   * The server would crash when `SHOW STATUS' was called on a server
     linked with `yaSSL'.  (Bug#18310 (http://bugs.mysql.com/18310))

   * The `ExtractValue()' function did not return an error when passed
     an invalid XPath string.  (Bug#18172 (http://bugs.mysql.com/18172))

   * Using the `position()' function in the XPath argument to
     `ExtractValue()' crashed the server.  (Bug#18171
     (http://bugs.mysql.com/18171))

   * `REPAIR TABLE', `OPTIMIZE TABLE', and `ALTER TABLE' operations on
     transactional tables (or on tables of any type on Windows) could
     corrupt triggers associated with those tables.  (Bug#18153
     (http://bugs.mysql.com/18153))

   * Connecting to a server with a UCS2 default character set with a
     client using a non-UCS2 character set crashed the server.
     (Bug#18004 (http://bugs.mysql.com/18004))

   * Using `ALTER TABLE ... REBUILD PARTITION' without specifying the
     name of the partition caused the server to crash, rather than
     reporting a syntax error.  (Bug#17947
     (http://bugs.mysql.com/17947))

   * `ALTER TABLE ... REBUILD PARTITION' with no partition name
     specified would crash the server.  (Bug#17940
     (http://bugs.mysql.com/17940))

   * A query with a `WHERE DATE_COLUMN > DATE_VALUE' condition failed
     on a table partitioned by `RANGE'.  (Bug#17894
     (http://bugs.mysql.com/17894))

   * Renaming and adding a new column to a partitioned table in the
     same `ALTER TABLE' statement caused the server to crash.
     (Bug#17772 (http://bugs.mysql.com/17772))

   * `MyISAM': Performing a bulk insert on a table referenced by a
     trigger would crash the table.  (Bug#17764
     (http://bugs.mysql.com/17764))

   * Using triggers with partitioned `InnoDB' tables led to incorrect
     results.  (Bug#17744 (http://bugs.mysql.com/17744))

   * Updating a view that filters certain rows to set a filtered out
     row to be included in the table caused infinite loop. For example,
     if the view has a WHERE clause of `salary > 100' then issuing an
     UPDATE statement of `SET salary = 200 WHERE id = 10', caused an
     infinite loop.  (Bug#17726 (http://bugs.mysql.com/17726))

   * A security enhancement in Visual Studio 8 could cause a MySQL
     debug server compiled with it to hang when running `SELECT'
     queries against partitioned tables.  (Bug#17722
     (http://bugs.mysql.com/17722))

   * The `EXAMPLE' storage engine did not work on Windows.  (Bug#17721
     (http://bugs.mysql.com/17721))

   * `ALTER TABLE ... REORGANIZE PARTITION' failed with `Error on
     rename of FILENAME ...' on Windows.  (Bug#17720
     (http://bugs.mysql.com/17720))

   * The MySQL server could crash with out of memory errors when
     performing aggregate functions on a `DECIMAL' column.  (Bug#17602
     (http://bugs.mysql.com/17602))

   * `NULL' values were written to the `mysql.slow_log' table
     incorrectly.  (Bug#17600 (http://bugs.mysql.com/17600))

   * `mysql_fix_privilege_tables' did not create the `mysql.plugin'
     table.  (Bug#17568 (http://bugs.mysql.com/17568))

   * Improper checking of binary log statements could result in a
     server crash.  (Bug#17457 (http://bugs.mysql.com/17457))

   * Rpeated invocations of a stored procedure containing a `SHOW
     CREATE EVENT' statement would result in the error `Packets out of
     order'.  (Bug#17403 (http://bugs.mysql.com/17403))

   * For `FEDERATED' tables, a `SELECT' statement with an `ORDER BY'
     clause did not return rows in the proper order.  (Bug#17377
     (http://bugs.mysql.com/17377))

   * `SELECT ... WHERE COLUMN LIKE 'A%'', when COLUMN had a key and
     used the `latin2_czech_cs' collation, caused the wrong number of
     rows to be returned.  (Bug#17374 (http://bugs.mysql.com/17374))

   * Calling `CREATE TABLE' or `ALTER TABLE' twice on a partitioned
     table in a stored procedure or a prepared statement resulted in
     errors and sometimes server crashes.  (Bug#17290
     (http://bugs.mysql.com/17290))

   * Checks for permissions on database operations could be performed
     in a case-insensitive manner (a user with permissions on database
     `MYDATABASE' could by accident get permissions on database
     `myDataBase'), if the privilege data were still cached from a
     previous check.  (Bug#17279 (http://bugs.mysql.com/17279))

   * Stored procedures that call UDFs and pass local string variables
     caused server crashes.  (Bug#17261 (http://bugs.mysql.com/17261))

   * A problem with `NULL's and interval mapping sometimes caused
     incorrect results or crashes when trying to use less-than searches
     on partitioned tables.  (Bug#17173 (http://bugs.mysql.com/17173))

   * Attempting to add a new partition to a table partitioned by a
     unique key would cause an `Out of memory' error.  (Bug#17169
     (http://bugs.mysql.com/17169))

   * Creating a table with the same name as the mapped name of another
     table caused a server crash. For example, if MySQL maps the table
     name `txu#P#p1' to `txu@0023P@0023p1' on disk, creating another
     table named `txu@0023P@0023p1' crashed the server.  (Bug#17142
     (http://bugs.mysql.com/17142))

   * Trying to add a partition to a table having subpartitions could
     crash the server.  (Bug#17140 (http://bugs.mysql.com/17140))

   * Use of `TRUNCATE TABLE' for a `TEMPORARY' table on a master server
     was propagated to slaves properly, but slaves did not decrement the
     `Slave_open_temp_tables' counter properly.  (Bug#17137
     (http://bugs.mysql.com/17137))

   * Attempting to use a conflicting `VALUES' clause in `ALTER TABLE
     ... ADD PARTITION' caused the server to crash. An example of such
     a conflicting clause would be that uses `VALUES LESS THAN
     (CONSTANT)' (which indicates a range) with a table that is
     partitioned by `LIST'.  (Bug#17127 (http://bugs.mysql.com/17127))

   * A failed `ALTER TABLE ... ADD PRIMARY KEY' on a partitioned table
     would result in bad table metadata and could possibly crash the
     server.  (Bug#17097 (http://bugs.mysql.com/17097))

   * Stored routine names longer than 64 characters were silently
     truncated. Now the limit is properly enforced and an error occurs.
     (Bug#17015 (http://bugs.mysql.com/17015))

   * Cursors in stored routines could cause a server crash.  (Bug#16887
     (http://bugs.mysql.com/16887))

   * Triggers created without `BEGIN' and `END' clauses resulted in
     `You have an error in your SQL syntax' errors when dumping and
     replaying a binary log.  (Bug#16878 (http://bugs.mysql.com/16878))

   * Using `ALTER TABLE' to increase the length of a `BINARY(M)' column
     caused column values to be padded with spaces rather than `0x00'
     bytes.  (Bug#16857 (http://bugs.mysql.com/16857))

   * `ALTER TABLE ... COALESCE PARTITION' failed with an `Out of
     Memory' error.  (Bug#16810 (http://bugs.mysql.com/16810))

   * `ALTER TABLE ... ADD COLUMN ... AFTER ...' failed when used on
     partitioned tables.  (Bug#16806 (http://bugs.mysql.com/16806))

   * If the server was started with the `--skip-grant-tables' option,
     it was impossible to create a trigger or a view without explicitly
     specifying a `DEFINER' clause.  (Bug#16777
     (http://bugs.mysql.com/16777))

   * In a highly concurrent environment, a server crash or deadlock
     could result from execution of a statement that used stored
     functions or activated triggers coincident with alteration of the
     tables used by these functions or triggers.  (Bug#16593
     (http://bugs.mysql.com/16593))

   * Clients compiled from source with the `--without-readline' did not
     save command history from session to session.  (Bug#16557
     (http://bugs.mysql.com/16557))

   * Using `ORDER BY INTVAR ' within a stored procedure (where INTVAR
     is an integer variable or expression) would crash the server.

     *Note*:

     The use of an integer I in an `ORDER BY I' clause for sorting the
     result by the I ^th column is deprecated (and non-standard). It
     should _not_ be used in new applications. See *Note select::.

     (Bug#16474 (http://bugs.mysql.com/16474))

   * Slow queries executed by scheduled events were not being written
     to the slow query log.  (Bug#16426 (http://bugs.mysql.com/16426))

   * `INSERT' statements executed by scheduled events were not written
     to the general log.  (Bug#16413 (http://bugs.mysql.com/16413))

   * Repeated invocations of a stored procedure containing a `CREATE
     EVENT' or `ALTER EVENT' statement would crash the server.
     (Bug#16408 (http://bugs.mysql.com/16408))

   * Names of subpartitions were not displayed in the output of `SHOW
     CREATE TABLE'.  (Bug#16370 (http://bugs.mysql.com/16370))

   * The `ExtractValue()' function would not accept expressions which
     matched element names containing an underscore character.
     (Bug#16320 (http://bugs.mysql.com/16320))

   * The `self()' XPath function was not handled correcty by
     `ExtractValue()'.  (Bug#16315 (http://bugs.mysql.com/16315))

   * The `ExtractValue()' function allowed the use of the `!' character
     in identifiers by ignoring the illegal character. This is now
     correctly reported as a syntax error.  (Bug#16313
     (http://bugs.mysql.com/16313))

   * Slave servers would retry the execution of a SQL statement an
     infinite number of times, ignoring the value
     `SLAVE_TRANSACTION_RETRIES' when using the NDB engine.  (Bug#16228
     (http://bugs.mysql.com/16228))

   * A memory leak caused warnings on slaves for certain statements
     that executed without warning on the master.  (Bug#16175
     (http://bugs.mysql.com/16175))

   * The `DEFINER' value for stored routines was not replicated.
     (Bug#15963 (http://bugs.mysql.com/15963))

   * No error was reported when subpartitions were defined for a
     non-subpartitioned table.  (Bug#15961
     (http://bugs.mysql.com/15961))

   * Character set conversion of string constants for `UNION' of
     constant and table column was not done when it was safe to do so.
     (Bug#15949 (http://bugs.mysql.com/15949))

   * The *Note `mysql_close()': mysql-close. C API function leaked
     handles for shared-memory connections on Windows.  (Bug#15846
     (http://bugs.mysql.com/15846))

   * A `SELECT' using a function against a nested view would crash the
     server.  (Bug#15683 (http://bugs.mysql.com/15683))

   * Setting up subpartitions on at least one but not all the
     partitions of a partitioned table caused the server to crash.
     (Bug#15407 (http://bugs.mysql.com/15407))

   * During conversion from one character set to `ucs2', multi-byte
     characters with no `ucs2' equivalent were converted to multiple
     characters, rather than to `0x003F QUESTION MARK'.  (Bug#15375
     (http://bugs.mysql.com/15375))

   * `CREATE TABLE ... PARTITION ... AS SELECT ...' would cause the
     server to crash.  (Bug#15336 (http://bugs.mysql.com/15336))

   * When attempting to insert a `0' into a `LIST'-partitioned table
     that had no value-list containing `0', no error was reported.
     (Bug#15253 (http://bugs.mysql.com/15253))

   * `SELECT COUNT(*)' for a `MyISAM' table could return different
     results depending on whether an index was used.  (Bug#14980
     (http://bugs.mysql.com/14980))

   * Stored routines that contained only a single statement were not
     written properly to the dumpfile when using `mysqldump'.
     (Bug#14857 (http://bugs.mysql.com/14857))

   * Execution of a stored function or trigger which inserted data into
     a table while running concurrent selects on the same table could
     result in storing incorrect data in the query cache.  (Bug#14767
     (http://bugs.mysql.com/14767))

   * Naming a partition using the characters *Ç* or *ç* (`c-cedilla';
     Unicode `00C7' or `00E7') made unreadable the table containing the
     partition.  (Bug#14527 (http://bugs.mysql.com/14527))

   * Searches on indexed columns of partitioned tables failed to find
     all matching rows following updates of the indexed columns.
     (Bug#14526 (http://bugs.mysql.com/14526))

   * Creating a partition which depends on an expression containing a
     column using the UTF8 character set would cause the server to
     crash.  (Bug#14367 (http://bugs.mysql.com/14367))

   * On Linux, creation of table partitions failed within a stored
     procedure.  (Bug#14363 (http://bugs.mysql.com/14363))

   * Invoking more than once a prepared statement that creates a
     partitioned table would crash the server.  (Bug#14350
     (http://bugs.mysql.com/14350))

   * The `RENAME TABLE' statement did not move triggers to the new
     table.  (Bug#13525 (http://bugs.mysql.com/13525))

   * The server would execute stored routines that had a non-existent
     definer.  (Bug#13198 (http://bugs.mysql.com/13198))

   * The length of a `VARCHAR()' column that used the `utf8' character
     set would increase each time the table was re-created in a stored
     procedure or prepared statement, eventually causing the `CREATE
     TABLE' statement to fail.  (Bug#13134
     (http://bugs.mysql.com/13134))

   * Loading of UDFs in a statically linked MySQL caused a server
     crash. UDF loading is now blocked if the MySQL server is
     statically linked.  (Bug#11835 (http://bugs.mysql.com/11835))

   * Setting the `myisam_repair_threads' system variable to a value
     larger than 1 could cause corruption of large `MyISAM' tables.
     (Bug#11527 (http://bugs.mysql.com/11527))

   * Issuing `GRANT EXECUTE' on a procedure would display any warnings
     related to the creation of the procedure.  (Bug#7787
     (http://bugs.mysql.com/7787))


File: manual.info,  Node: news-5-1-7,  Next: news-5-1-6,  Prev: news-5-1-8,  Up: news-5-1-x

C.1.23 Changes in MySQL 5.1.7 (27 February 2006)
------------------------------------------------

Functionality added or changed:

   * *Incompatible Change*: The `mysql_stmt_attr_get()' C API function
     now returns a boolean rather than an unsigned int for
     `STMT_ATTR_UPDATE_MAX_LENGTH'.  (Bug#16144
     (http://bugs.mysql.com/16144))

   * *Incompatible Change*: Due to a change in the naming scheme for
     partitioning and subpartitioning files, it is not possible for the
     server to read partitioned tables created in previous MySQL
     versions.  Attempting to read pre-5.1.6 partitioned tables with a
     MySQL 5.1.7 or later server now generates a suitable warning
     message.

     Two possible workarounds are:

        *            1. Create a non-partitioned table with the same table
               schema using a standard `CREATE TABLE' statement (that
               is, with no partitioning clauses)

            2. Issue a `SELECT INTO' to copy the data into the
               non-partitioned table before the upgrade

          Following the upgrade, you can partition the new table using
          `ALTER TABLE ... PARTITION BY ...'.

        * Alternatively, you can dump the table using `mysqldump' prior
          to upgrading and reload it afterwards with `LOAD DATA'.

     In either case, you should drop the pre-5.1.6 partitioned tables
     before upgrading to 5.1.6 or later.

     *Important*:

     If any partitioned tables that were created prior to MySQL 5.1.6
     are present following an upgrade to MySQL 5.1.6 or later, it is
     also not possible to read from the `INFORMATION_SCHEMA.PARTITIONS'
     table, nor will you be able to drop those tables or the database or
     databases in which they are located. In this event, you must:

       1. Shut down `mysqld'

       2. Manually delete the table, partition, and (if any)
          subpartition files

       3. Restart the MySQL Server

     (Bug#13437 (http://bugs.mysql.com/13437), Bug#16695
     (http://bugs.mysql.com/16695))

   * *Incompatible Change*: `TYPE = ENGINE_NAME ' is no longer accepted
     as a synonym for the `ENGINE = ENGINE_NAME ' table option. (`TYPE'
     has been deprecated since MySQL 4.0.)

   * *MySQL Cluster*: Attempting to `SELECT ... FROM
     INFORMATION_SCHEMA.FILES' now raises a warning in the event that
     the cluster has crashed.  (Bug#17087 (http://bugs.mysql.com/17087))

   * *Disk Data*: Status messages have been added to `ndb_restore' to
     enable users to know that data files for Disk Data are being
     created.  (Bug#16873 (http://bugs.mysql.com/16873))

   * *Cluster Replication*: It is now possible to replicate `NDB' tables
     having no explicit primary key. See *Note
     mysql-cluster-replication::.

   * Creator privileges are now checked for all events before execution.
     (Bug#17289 (http://bugs.mysql.com/17289))

   * `CREATE EVENT', `DROP EVENT', and `ALTER EVENT' statements are not
     allowed in triggers.  (Bug#16410 (http://bugs.mysql.com/16410))

   * The SQL mode in effect at the time an event is created or altered
     is recorded and used during event execution.  (Bug#16407
     (http://bugs.mysql.com/16407))

   * New `charset' command added to `mysql' command-line client. By
     typing `charset NAME' or `\C NAME' (such as `\C UTF8'), the client
     character set can be changed without reconnecting.  (Bug#16217
     (http://bugs.mysql.com/16217))

   * Added the `--wait-timeout' option to `mysqlmanager' to allow
     configuration of the timeout for dropping an inactive connection,
     and increased the default timeout from 30 seconds to 28,800
     seconds (8 hours).  (Bug#15980 (http://bugs.mysql.com/15980),
     Bug#12674 (http://bugs.mysql.com/12674))

   * All subpartitions within a given partitioned table are now
     guaranteed to have unique names.  (Bug#15408
     (http://bugs.mysql.com/15408))

   * `mysqlimport' now has a `--use-threads=N' option for loading data
     files in parallel using N threads.

   * Added the `--check-upgrade' to `mysqlcheck' that invokes `CHECK
     TABLE' with the `FOR UPGRADE' option.  Added the `--fix-db-names'
     and `--fix-table-names' options to `mysqlcheck'.

   * Added the `RENAME DATABASE' statement.

   * Added the `PROCESSLIST' table to `INFORMATION_SCHEMA'.

   * Added the `FOR UPGRADE' option for the `CHECK TABLE' statement.
     This option checks whether tables are incompatible with the
     current version of MySQL Server.

   * In row-based replication, when executing a Rows_log_event, the
     associated table was locked, the rows applied and the lock
     released. This did not work since there are storage engines that
     count locks and perform an autocommit when the number of locks
     reach zero. Now we ensure that all table maps come before all
     `ROWS' events in a statement.

   * Removed the `have_isam' and `have_raid' system variables.

   * Several changes were made to make upgrades easier:

        * Added the `mysql_upgrade' program that checks all tables for
          incompatibilities with the current version of MySQL Server
          and repairs them if necessary. This program should be run for
          each MySQL upgrade (rather than
          `mysql_fix_privilege_tables'). See *Note mysql-upgrade::.

        * Added the `FOR UPGRADE' option for the `CHECK TABLE'
          statement. This option checks whether tables are incompatible
          with the current version of MySQL Server.

        * Added the `--check-upgrade' to `mysqlcheck' that invokes
          `CHECK TABLE' with the `FOR UPGRADE' option. Added the
          `--fix-db-names' and `--fix-table-names' options to
          `mysqlcheck'.

   * Added the `mysql_upgrade' program that checks all tables for
     incompatibilities with the current version of MySQL Server and
     repairs them if necessary. This program should be run for each
     MySQL upgrade (rather than `mysql_fix_privilege_tables'). See
     *Note mysql-upgrade::.

   * Added the `IN NATURAL LANGUAGE MODE' and `IN NATURAL LANGUAGE MODE
     WITH QUERY EXPANSION' modifiers for full-text searches. See *Note
     fulltext-search::.

Bugs fixed:

   * *MySQL Cluster*: Creating `NDB' tables containing `BLOB' columns
     but no primary key caused unpredictable behavior.  (Bug#17559
     (http://bugs.mysql.com/17559))

   * *MySQL Cluster*: Inserting the output of `REPEAT('SOME_STRING',
     SOME_INT)' into a `BLOB' column resulted in the error `Invalid
     blob attributes or invalid blob parts table'.  (Bug#17505
     (http://bugs.mysql.com/17505))

   * *MySQL Cluster*: `ndbd' restarts could sometimes fail due to
     incorrect memory access.  (Bug#17417 (http://bugs.mysql.com/17417))

   * *MySQL Cluster*: Sharing of table names containing special
     characters between multiple SQL nodes was not handled correctly
     when binary logging was enabled (a timeout error resulted).
     (Bug#17415 (http://bugs.mysql.com/17415))

   * *MySQL Cluster*: Table definitions were not shared between
     multiple SQL nodes in a cluster without binary logging being
     enabled.  (Bug#17414 (http://bugs.mysql.com/17414))

   * *MySQL Cluster*: Cluster log file paths were truncated to 128
     characters. They may now be as long as `MAX_PATH' (the maximum
     path length permitted by the operating system).  (Bug#17411
     (http://bugs.mysql.com/17411))

   * *MySQL Cluster*: `SHOW CREATE TABLE' would fail when run against a
     table created in a different session.  (Bug#17340
     (http://bugs.mysql.com/17340))

   * *MySQL Cluster*: Following multiple forced shutdowns and restarts
     of data nodes, `DROP DATABASE' could fail.  (Bug#17325
     (http://bugs.mysql.com/17325))

   * *MySQL Cluster*: The `REDO' log would become corrupted (and thus
     unreadable) in some circumstances, due to a failure in the query
     handler.  (Bug#17295 (http://bugs.mysql.com/17295))

   * *MySQL Cluster*: An `UPDATE' with an inner join failed to match
     any records if both tables in the join did not have a primary key.
     (Bug#17257 (http://bugs.mysql.com/17257))

   * *MySQL Cluster*: A `DELETE' with a join in the `WHERE' clause
     failed to retrieve any records if both tables in the join did not
     have a primary key.  (Bug#17249 (http://bugs.mysql.com/17249))

   * *MySQL Cluster*: `CREATE TEMPORARY TABLE' of a Cluster table would
     fail with an `Unsupported' error or crash the server.  (Bug#17210
     (http://bugs.mysql.com/17210), Bug#16552
     (http://bugs.mysql.com/16552))

   * *MySQL Cluster*: The storage engine did not allow views to be
     updated.  (Bug#17206 (http://bugs.mysql.com/17206))

   * *MySQL Cluster*: When attempting to import data into an `NDB'
     table using `LOAD DATA INFILE', the server would hang in the event
     of a duplicate key error.  (Bug#17154
     (http://bugs.mysql.com/17154))

   * *MySQL Cluster*: In some cases, `LOAD DATA INFILE' did not load
     all data into `NDB' tables.  (Bug#17081
     (http://bugs.mysql.com/17081))

   * *MySQL Cluster*: `CREATE TABLE NEW_TBL LIKE OLD_TBL;' failed when
     OLD_TBL used the `NDB' storage engine.  (Bug#17005
     (http://bugs.mysql.com/17005))

   * *MySQL Cluster*: An unhandled resources issue could cause node
     failure with a `DELETE FROM TABLE' affecting thousands of rows.
     (Bug#16492 (http://bugs.mysql.com/16492))

   * *MySQL Cluster*: `UNIQUE' keys in Cluster tables were limited to
     225 bytes in length.  (Bug#15918 (http://bugs.mysql.com/15918))

   * *MySQL Cluster*: `REPLACE' failed when attempting to update a
     primary key value in a Cluster table.  (Bug#14007
     (http://bugs.mysql.com/14007))

   * *MySQL Cluster*: No error message was generated for setting
     `NoOfFragmentLogFiles' too low.  (Bug#13966
     (http://bugs.mysql.com/13966))

   * *MySQL Cluster*: No error message was generated for setting
     `MaxNoOfAttributes' too low.  (Bug#13965
     (http://bugs.mysql.com/13965))

   * *MySQL Cluster*: Performing large numbers of data manipulation
     statements on cluster tables using Disk Data could lead to a
     server crash.

   * *Disk Data*: In some cases, a cluster using Disk Data tables could
     not be restarted following a normal shutdown.  (Bug#16872
     (http://bugs.mysql.com/16872))

   * *Cluster Replication*: Row-based replication was not set up
     correctly if a backup was already in progress. For example,
     connecting a `mysqld' instance to a cluster which was being backed
     up would result in the message `NDB: skipping setup table TBL_NAME'
     being written to the error log.  (Bug#17459
     (http://bugs.mysql.com/17459))

   * *Cluster Replication*: Row-based replication of a cluster failed
     to take `--binlog_ignore_db settings' into account.  (Bug#17188
     (http://bugs.mysql.com/17188))

   * *Cluster Replication*: Cluster tables not having an explicit
     primary key could not be replicated.  (Bug#14541
     (http://bugs.mysql.com/14541))

   * Column counts were encoded incorrectly in the binary log for
     row-based logging format.  (Bug#17678
     (http://bugs.mysql.com/17678))

   * Data truncations on non-`UNIQUE' indexes could crash `InnoDB' when
     using multi-byte character sets.  (Bug#17530
     (http://bugs.mysql.com/17530))

   * An `ALTER DATABASE' statement on a replication master crashed the
     slaves.  (Bug#17521 (http://bugs.mysql.com/17521))

   * Execution times for scheduled events were not calculated
     correctly: the last execution time was used as a base rather than
     the actual start time.  (Bug#17494 (http://bugs.mysql.com/17494))

   * Creating an event and using a whitespace character other than
     space following the `DO' keyword caused a server crash.
     (Bug#17453 (http://bugs.mysql.com/17453))

   * Partitioning with certain `SUBPARTITION BY HASH' clauses caused an
     error when querying for a partitioned column using an `IS NULL'
     comparison.  (Bug#17430 (http://bugs.mysql.com/17430), Bug#17432
     (http://bugs.mysql.com/17432))

   * Race conditions between event creation, dropping, and execution
     could result in a server crash or hang.  (Bug#17373
     (http://bugs.mysql.com/17373))

   * Trying to create a partitioned table with more than 32 attributes
     failed.  (Bug#17179 (http://bugs.mysql.com/17179))

   * Attempting to add a new partition to a table partitioned by a
     unique key would cause an `Out of memory' error.  (Bug#17169
     (http://bugs.mysql.com/17169))

   * `myisam_ftdump' did not work for `FULLTEXT' indexes associated
     with a parser plugin.  (Bug#17116 (http://bugs.mysql.com/17116))

   * On Windows platforms, some attempts to create partitioned tables
     from the command line would cause the `mysql' client to hang.
     (Bug#17082 (http://bugs.mysql.com/17082))

   * A `SELECT' from the last partition of a subpartitioned table
     having a `UNIQUE KEY' could crash the MySQL Server.  (Bug#16907
     (http://bugs.mysql.com/16907))

   * Statements that contained Unicode characters were not logged to
     the log tables correctly.  (Bug#16905
     (http://bugs.mysql.com/16905))

   * A `SELECT' on a subpartitioned table having a multiple-column
     `PRIMARY' or `UNIQUE KEY', and whose partitioning function used
     only the first column of the key, could cause `mysqld' to crash.
     (Bug#16901 (http://bugs.mysql.com/16901))

   * A `RETURN' statement within a trigger caused a server crash.
     `RETURN' now is disallowed within triggers. To exit immediately,
     use `LEAVE'.  (Bug#16829 (http://bugs.mysql.com/16829))

   * Using `REPLACE INTO' on a partitioned table having a primary key
     would crash the server in the event of a duplicate key error.
     (Bug#16782 (http://bugs.mysql.com/16782))

   * `DROP TABLE' would sometimes fail on a table having subpartitions
     that used the default storage engine.  (Bug#16775
     (http://bugs.mysql.com/16775))

   * If the query optimizer transformed a `GROUP BY' clause in a
     subquery, it did not also transform the `HAVING' clause if there
     was one, producing incorrect results.  (Bug#16603
     (http://bugs.mysql.com/16603))

   * Querying the `INFORMATION_SCHEMA.PARTITIONS' table on a non-max
     server caused a server crash. This also happened following the
     creation of a table with a very large number (hundreds) of
     partitions.  (Bug#16591 (http://bugs.mysql.com/16591), Bug#17141
     (http://bugs.mysql.com/17141))

   * For a transaction that used `MyISAM' and `InnoDB' tables,
     interruption of the transaction due to a dropped connection on a
     master server caused slaves to lose synchrony.  (Bug#16559
     (http://bugs.mysql.com/16559))

   * `SHOW CREATE EVENT' displayed no output.  (Bug#16423
     (http://bugs.mysql.com/16423))

   * `DROP DATABASE' did not drop events for the database.  (Bug#16406
     (http://bugs.mysql.com/16406))

   * The `mysql_fix_privilege_tables.sql' script did not properly
     initialize the `Event_priv' column to `'Y'' for those accounts
     that should have the `EVENT' privilege.  (Bug#16400
     (http://bugs.mysql.com/16400))

   * `SELECT' with `GROUP BY' on a view could cause a server crash.
     (Bug#16382 (http://bugs.mysql.com/16382))

   * MySQL server dropped client connection for certain `SELECT'
     statements against views defined that used `MERGE' algorithm.
     (Bug#16260 (http://bugs.mysql.com/16260))

   * Using an XPath expression containing `=' with `ExtractValue()'
     caused the server to crash.  (Bug#16242
     (http://bugs.mysql.com/16242))

   * When used with the `ExtractValue()' function, an XPath expression
     having no leading ` `/' ' character would crash the server.
     (Bug#16234 (http://bugs.mysql.com/16234))

   * Using `GROUP BY' on column used in `WHERE' clause could cause
     empty set to be returned.  (Bug#16203
     (http://bugs.mysql.com/16203))

   * `CAST(... AS TIME)' operations returned different results when
     using versus not using prepared-statement protocol.  (Bug#15805
     (http://bugs.mysql.com/15805))

   * The `SELECT' privilege was required for triggers that performed no
     selects.  (Bug#15196 (http://bugs.mysql.com/15196))

   * The `UPDATE' privilege was required for triggers that performed no
     updates.  (Bug#15166 (http://bugs.mysql.com/15166))

   * A statement containing `GROUP BY' and `HAVING' clauses could
     return incorrect results when the `HAVING' clause contained logic
     that returned `FALSE' for every row.  (Bug#14927
     (http://bugs.mysql.com/14927))

   * Killing a long-running query containing a subquery could cause a
     server crash.  (Bug#14851 (http://bugs.mysql.com/14851))

   * Previously, a stored function invocation was written to the binary
     log as `DO FUNC_NAME()' if the invocation changes data and occurs
     within a non-logged statement, or if the function invokes a stored
     procedure that produces an error. These invocations now are logged
     as `SELECT FUNC_NAME()' instead for better control over error code
     checking (slave servers could stop due to detecting a different
     error than occurred on the master).  (Bug#14769
     (http://bugs.mysql.com/14769))

   * `SUBSTRING_INDEX()' could yield inconsistent results when applied
     with the same arguments to consecutive rows in a query.
     (Bug#14676 (http://bugs.mysql.com/14676))

   * `SET sql_mode = N', where N > 31, did not work properly.
     (Bug#13897 (http://bugs.mysql.com/13897))

   * `SHOW CREATE TABLE' produced extraneous spaces following the
     keywords ` `PRIMARY KEY' '.  (Bug#13883
     (http://bugs.mysql.com/13883))

   * `BIT' fields were not properly handled when using row-based
     replication.  (Bug#13418 (http://bugs.mysql.com/13418))

   * `InnoDB' could display an incorrect error message for a cascading
     update.  (Bug#9680 (http://bugs.mysql.com/9680))

   * `CHECKSUM TABLE' returned different values for `MyISAM' tables
     depending on whether the `QUICK' or `EXTENDED' option was used.
     (Bug#8841 (http://bugs.mysql.com/8841))

   * `SET TRANSACTION ISOLATION LEVEL' acted like `SET SESSION
     TRANSACTION ISOLATION LEVEL'. That is, it set the isolation level
     for longer than the next transaction.  (Bug#7955
     (http://bugs.mysql.com/7955))

   * Repeated invocation of `my_init()' and `my_end()' caused
     corruption of character set data and connection failure.
     (Bug#6536 (http://bugs.mysql.com/6536))


File: manual.info,  Node: news-5-1-6,  Next: news-5-1-5,  Prev: news-5-1-7,  Up: news-5-1-x

C.1.24 Changes in MySQL 5.1.6 (01 February 2006)
------------------------------------------------

Functionality added or changed:

   * *Incompatible Change*: Words with apostrophes are now matched in a
     FULLTEXT search against non-apostrophe words (for example, a
     search for `Jerry' will match against the term `Jerry's'). Users
     upgrading to this version must issue `REPAIR TABLE ... QUICK'
     statements for tables containing `FULLTEXT' indexes.  (Bug#14194
     (http://bugs.mysql.com/14194))

   * *Incompatible Change*: This release introduces the `TRIGGER'
     privilege. Previously, the `SUPER' privilege was needed to create
     or drop triggers. Now those operations require the `TRIGGER'
     privilege. This is a security improvement because you no longer
     need to grant users the `SUPER' privilege to enable them to create
     triggers. However, the requirement that the account named in a
     trigger's `DEFINER' clause must have the `SUPER' privilege has
     changed to a requirement for the `TRIGGER' privilege. After
     upgrading, be sure to update your grant tables as described in
     *Note mysql-fix-privilege-tables::. This process assigns the
     `TRIGGER' privilege to all accounts that had the `SUPER'
     privilege. (After updating, you might also consider whether any of
     those accounts no longer need `SUPER'.) If you fail to update the
     grant tables, triggers may fail when activated.  (Bug#9142
     (http://bugs.mysql.com/9142))

   * *Incompatible Change*: Before MySQL 5.1.6, the server writes
     general query log and slow query log entries to log files. As of
     MySQL 5.1.6, the server's logging capabilities for these logs are
     more flexible. Log entries can be written to log files (as before)
     or to the `general_log' and `slow_log' tables in the `mysql'
     database. If logging is enabled, either or both destinations can
     be selected. The `--log-output' option controls the destination or
     destinations of log output. See *Note log-tables::.

     If logging is enabled, the default destination now is to log to
     tables, which differs from earlier versions. If you had the server
     configured for logging to log files formerly, use
     `--log-output=FILE' to preserve this behavior after an upgrade to
     MySQL 5.1.6 or higher.

   * *Important Change*: *MySQL Cluster*: *Replication*: Replication
     between MySQL Clusters is now supported. It is now also possible
     to replicate between a MySQL Cluster and a non-cluster database.
     See *Note mysql-cluster-replication::, for more information.

   * *MySQL Cluster*: Added the `ndb_extra_logging' system variable.

   * *MySQL Cluster*: The `NDB' storage engine now supports the `CREATE
     INDEX' and `DROP INDEX' statements.

   * *Packaging*: MySQL 5.1.6 introduces some changes to distribution
     packaging:

        * Distributions include both a `mysqld' optimized server and
          `mysqld-debug' debugging server. There is no separate debug
          distribution.

        * There is no longer a `mysqld-max' server.  (Note: This
          changed in MySQL 5.1.9: The `mysqld-max' server also is
          included in binary distributions.)

        * Server binaries no longer are stripped, except for RPM
          distributions.

        * Binary distributions for Unix and Unix-like systems no longer
          include `safe_mysqld' as a link to `mysqld_safe'.
          `safe_mysqld' has been deprecated since MySQL 4.0 and now is
          removed.

   * The `mysqldump' utility now supports an option for dumping
     tablespaces. Use `-Y' or `--all-tablespaces' to enable this
     functionality.  (Bug#16753 (http://bugs.mysql.com/16753))

   * Partition support is not an `engine', but it was included in the
     output of `SHOW ENGINES'. Now it is not. The
     `have_partition_engine' variable was renamed to
     `have_partitioning'.  (Bug#14355 (http://bugs.mysql.com/14355),
     Bug#16718 (http://bugs.mysql.com/16718))

   * `ANALYZE TABLE' is now supported for partitioned tables.
     (Bug#13441 (http://bugs.mysql.com/13441))

   * Added the `--use-threads' option for `mysqlslap'.

   * Queries against partitioned tables can now take advantage of
     partition pruning. In some cases, this can result in query
     execution that is an order of magnitude faster than the same query
     against a non-partitioned version of the same table.

   * There is no longer a `mysqld-max' server.  (Note: This changed in
     MySQL 5.1.9: The `mysqld-max' server also is included in binary
     distributions.)

   * Added the `FILES' table to `INFORMATION_SCHEMA'.

   * Binary distributions for Unix and Unix-like systems no longer
     include `safe_mysqld' as a link to `mysqld_safe'. `safe_mysqld'
     has been deprecated since MySQL 4.0 and now is removed.

   * Special characters in database and table identifiers now are
     encoded when creating the corresponding directory names and
     filenames. This relaxes the restrictions on the characters that
     can appear in identifiers. See *Note identifier-mapping::.

   * Added the `event_scheduler' system variable.

   * MySQL 5.1.6 introduces the _Event Scheduler_ which allows one to
     schedule statements for execution at predetermined times. Events
     can be transient (one-time-only) or recurrent at regular
     intervals, and may execute queries and statements permitted in
     stored routines, including compound statements.

     Events can be altered after creation, and dropped when no longer
     needed.

     Information about scheduled events can be obtained using the
     statements `SHOW EVENTS' and `SHOW CREATE EVENT', or by querying
     the `INFORMATION_SCHEMA.EVENTS' table. All of these are available
     beginning in MySQL 5.1.6.

     Users must have the `EVENT' privilege (also added in 5.1.6) to
     create events.

     For more information, see *Note events::.

   * Distributions include both a `mysqld' optimized server and
     `mysqld-debug' debugging server.  There is no separate debug
     distribution.

   * Server binaries no longer are stripped, except for RPM
     distributions.

   * The `ARCHIVE' storage engine now supports the `AUTO_INCREMENT'
     column attribute and the `AUTO_INCREMENT' table option.  *Note
     archive-storage-engine::.

   * Server plugins can register their own status variables to be
     displayed by the `SHOW STATUS' statement.

   * Added the `PARTITIONS' table to `INFORMATION_SCHEMA'.

   * Added the `EVENTS' table to `INFORMATION_SCHEMA'.

Bugs fixed:

   * *MySQL Cluster*: `NDB' leaked disk space when performing repeated
     `INSERT' or `DELETE' statements.  (Bug#16771
     (http://bugs.mysql.com/16771))

   * *MySQL Cluster*: `ndb_delete_all' ran out of memory when
     processing tables containing `BLOB' columns.  (Bug#16693
     (http://bugs.mysql.com/16693))

   * *MySQL Cluster*: Trying to import too many dumped tables requiring
     resources beyond those allocated in the cluster configuration file
     caused the server to crash instead of reporting an insufficient
     resources error.  (Bug#16455 (http://bugs.mysql.com/16455))

   * *MySQL Cluster*: A `BIT' column whose offset and length totaled 32
     caused the cluster to crash.  (Bug#16125
     (http://bugs.mysql.com/16125))

   * *MySQL Cluster*: The `ndb_autodiscover' test failed sporadically
     due to a node not being permitted to connect to the cluster.
     (Bug#15619 (http://bugs.mysql.com/15619))

   * *MySQL Cluster*: `NDB' returned an incorrect `Can't find file
     error' for OS error 24; this has been changed to `Too many open
     files'.  (Bug#15020 (http://bugs.mysql.com/15020))

   * *MySQL Cluster*: `CREATE TABLESPACE' statements were incorrectly
     parsed on 64-bit platforms. (`INITIAL SIZE SIZE' worked, but
     `INITIAL SIZE = SIZE ' failed.)  (Bug#13556
     (http://bugs.mysql.com/13556))

   * *MySQL Cluster*: Using `mysqldump' to obtain a dump of a
     partitioned table employing the `NDB' storage engine produced a
     non-functional table creation statement.  (Bug#13155
     (http://bugs.mysql.com/13155))

   * *Disk Data*: Tablespaces created using parameters with relatively
     low values (10 MB or less) produced filesizes much smaller than
     expected.  (Bug#16742 (http://bugs.mysql.com/16742))

   * *Disk Data*: `NDB' returned the wrong error when the tablespace on
     disk was full.  (Bug#16738 (http://bugs.mysql.com/16738))

   * *Disk Data*: The error message generated by a failed `ADD
     UNDOFILE' did not provide any reasons for the failure.  (Bug#16267
     (http://bugs.mysql.com/16267))

   * *Disk Data*: `DROP LOGFILE GROUP' corrupted the cluster file
     system and caused `ndbd' to fail when running more than one node
     on the same system.  (Bug#16193 (http://bugs.mysql.com/16193))

   * *Cluster API*: Upon the completion of a scan where a key request
     remained outstanding on the primary replica and a starting node
     died, the scan did not terminate. This caused incomplete error
     handling for the failed node.  (Bug#15908
     (http://bugs.mysql.com/15908))

   * When the fulltext search parser plugin returned more words than
     half of the length (in bytes) of the query string, the server
     would crash.  (Bug#16722 (http://bugs.mysql.com/16722))

   * An indexing error sometimes caused values to be assigned to the
     wrong `RANGE' partition.  (Bug#16684 (http://bugs.mysql.com/16684))

   * An `INSERT' statement in a stored procedure corrupted the binary
     log.  (Bug#16621 (http://bugs.mysql.com/16621))

   * Trying to add more than one partition in a single `ALTER TABLE ...
     ADD PARTITION' statement caused the server to crash.  (Bug#16534
     (http://bugs.mysql.com/16534))

   * Parallel builds occasionally failed on Solaris.  (Bug#16282
     (http://bugs.mysql.com/16282))

   * Inserting a negative value into an integer column used as the
     partitioning key for a table partitioned by `HASH' could cause the
     server to crash.  (Bug#15968 (http://bugs.mysql.com/15968))

   * Creating a partitioned table using a storage engine other than the
     session default storage engine caused the server to crash.
     (Bug#15966 (http://bugs.mysql.com/15966))

   * The error message for specifying values for which no partition
     exists returned wrong values on certain platforms.  (Bug#15910
     (http://bugs.mysql.com/15910))

   * Specifying a value for `--tmpdir' without a trailing slash had
     unpredictable results.  (Bug#15904 (http://bugs.mysql.com/15904))

   * `STR_TO_DATE(1,NULL)' caused a server crash.  (Bug#15828
     (http://bugs.mysql.com/15828), CVE-2006-3081
     (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-3081))

   * `ALTER TABLE ... ADD PARTITIONS' on a table with one partition
     crashed the server.  (Bug#15820 (http://bugs.mysql.com/15820))

   * The `mysql_real_connect()' C API function incorrectly reset the
     `MYSQL_OPT_RECONNECT' option to its default value.  (Bug#15719
     (http://bugs.mysql.com/15719))

   * In some cases the query optimizer did not properly perform
     multiple joins where inner joins followed left joins, resulting in
     corrupted result sets.  (Bug#15633 (http://bugs.mysql.com/15633))

   * Certain permission management statements could create a `NULL'
     hostname for a user, resulting in a server crash.  (Bug#15598
     (http://bugs.mysql.com/15598))

   * Improper memory handling for stored routine variables could cause
     memory overruns and binary log corruption.  (Bug#15588
     (http://bugs.mysql.com/15588))

   * The absence of a table in the left part of a left or right join
     was not checked prior to name resolution, which resulted in a
     server crash.  (Bug#15538 (http://bugs.mysql.com/15538))

   * An `ALTER TABLE ... PARTITION BY ...' statement did not have any
     effect.  (Bug#15523 (http://bugs.mysql.com/15523))

   * Using `RANGE' partitioning with a `CASE' expression as the
     partitioning function would cause records to be placed in the
     wrong partition.  (Bug#15393 (http://bugs.mysql.com/15393))

   * Certain subqueries where the inner query was the result of a
     aggregate function would return different results with MySQL 5.1
     than with MySQL 4.1.

     Subselects could also return wrong results when the query cache
     and grouping were involved.  (Bug#15347
     (http://bugs.mysql.com/15347))

   * Attempting to insert data into a partitioned table that used the
     `BLACKHOLE' storage engine caused `mysqld' to crash.  (Bug#14524
     (http://bugs.mysql.com/14524))

   * A `FULLTEXT' query in a prepared statement could result in
     unexpected behavior.  (Bug#14496 (http://bugs.mysql.com/14496))

   * With a table partitioned by `LIST', inserting a value which was
     smaller than any value shown in the partitioning value-lists could
     cause the server to crash.  (Bug#14365
     (http://bugs.mysql.com/14365))

   * The `DATA DIRECTORY' and `INDEX DIRECTORY' clauses of a `CREATE
     TABLE' statement involving partitions did not work.  (Bug#14354
     (http://bugs.mysql.com/14354))

   * `SHOW CREATE TABLE' did not display the `PARTITIONS' clause for
     tables partitioned by `HASH' or `KEY'.  (Bug#14327
     (http://bugs.mysql.com/14327))

   * `ALTER TABLE ... DROP PARTITION' would truncate all `DATE' column
     values in the table's remaining partitions to `NULL'.  (Bug#13644
     (http://bugs.mysql.com/13644))

   * `ALTER TABLE ... ADD PARTITION' could crash the server or cause an
     `Out of memory' error in some circumstances.  (Bug#13447
     (http://bugs.mysql.com/13447))

   * The server would allow foreign keys to be declared in the
     definition of a partitioned table despite the fact that
     partitioned tables do not support foreign keys (see *Note
     partitioning-limitations::).  (Bug#13446
     (http://bugs.mysql.com/13446))

   * A `SELECT' from a key-partitioned table with a multi-column key
     could cause the server to crash.  (Bug#13445
     (http://bugs.mysql.com/13445))

   * Issuing a `TRUNCATE' statement twice in succession on the same
     partitioned table would cause the server to crash.  (Bug#13442
     (http://bugs.mysql.com/13442))

   * Using a `REPLACE' statement on a partitioned table caused the
     server to crash.  (Bug#13440 (http://bugs.mysql.com/13440))

   * Using an identifier rather than a literal integer value in the
     `LESS THAN' clause of a range-partitioned table could cause the
     server to crash and corruption of tables.  (Bug#13439
     (http://bugs.mysql.com/13439))

   * Using `ENGINE=...' within a `PARTITION' clause could cause the
     server to crash.  (Bug#13438 (http://bugs.mysql.com/13438))

   * `CREATE TABLE ... LIKE' did not work if the table whose schema was
     to be copied was a partitoned table.  (Bug#13435
     (http://bugs.mysql.com/13435))

   * Multi-byte path names for `LOAD DATA' and `SELECT ... INTO
     OUTFILE' caused errors. Added the `character_set_filesystem'
     system variable, which controls the interpretation of string
     literals that refer to filenames.  (Bug#12448
     (http://bugs.mysql.com/12448))

   * Temporary table aliasing did not work inside stored functions.
     (Bug#12198 (http://bugs.mysql.com/12198))

   * Using the `TRUNCATE()' function with a negative number for the
     second argument on a `BIGINT' column returned incorrect results.
     (Bug#8461 (http://bugs.mysql.com/8461))

   * Certain Japanese table names were not properly saved during a
     `CREATE TABLE' statement.  (Bug#3906 (http://bugs.mysql.com/3906))


File: manual.info,  Node: news-5-1-5,  Next: news-5-1-4,  Prev: news-5-1-6,  Up: news-5-1-x

C.1.25 Changes in MySQL 5.1.5 (10 January 2006)
-----------------------------------------------

Functionality added or changed:

   * Added the `--port-open-timeout' option to `mysqld' to control how
     many seconds the server should wait for the TCP/IP port to become
     free if it cannot be opened.  (Bug#15591
     (http://bugs.mysql.com/15591))

   * Added the `--create-schema', `--lock-directory',
     `--number-of-queries', `--only-print', `--preserve-schema', and
     `--slave' options for `mysqlslap'.

   * Added the `--base64-output' option to `mysqlbinlog' to print all
     binary log entries using base64 encoding. This is for debugging
     only. Logs produced using this option should not be applied on
     production systems.

   * Added the `INFORMATION_SCHEMA PLUGINS' table and the `SHOW PLUGIN'
     statement.

   * Added the `binlog_format' system variable that controls whether to
     use row-based or statement-based binary logging. Added the
     `--binlog-format' and `--binlog-row-event-max-size' server options
     for binary logging control. See *Note replication-formats::.

   * Two new Hungarian collations are included: `utf8_hungarian_ci' and
     `ucs2_hungarian_ci'. These support the correct sort order for
     Hungarian vowels. However, they do not support the correct order
     for sorting Hungarian consonant contractions; we expect to fix
     this issue in a future release.

   * Plugins now can have status variables that are displayed in the
     output from `SHOW STATUS'. See *Note plugin-writing::.

   * Added the `INFORMATION_SCHEMA ENGINES' table.

   * Added the XML functions `ExtractValue()' and `UpdateXML()'.
     `ExtractValue()' returns the content of a fragment of XML matching
     a given XPath expression.  `UpdateXML()' replaces the element
     selected from a fragment of XML by an XPath expression supplied by
     the user with a second XML fragment (also user-supplied), and
     returns the modified XML. See *Note xml-functions::.

Bugs fixed:

   * `INSERT DELAYED' caused `mysqld' to crash.  (Bug#16095
     (http://bugs.mysql.com/16095))

   * The `--plugin_dir' option was not working.  Specifying the parser
     name for fulltext also did not work correctly.  (Bug#16068
     (http://bugs.mysql.com/16068))

   * Attempting to insert into a table partitioned by `LIST' a value
     less than any specified in one of the table's partition
     definitions resulted in a server crash.  In such cases, `mysqld'
     now returns `ERROR 1500 (HY000): Table has no partition for value
     V ' , where V is the out-of-range value.  (Bug#15819
     (http://bugs.mysql.com/15819))

   * Issuing a `DROP USER' command could cause some users to encounter
     a ` HOSTNAME is not allowed to connect to this MySQL server' error.
     (Bug#15775 (http://bugs.mysql.com/15775))

   * The output of `mysqldump --triggers' did not contain the `DEFINER'
     clause in dumped trigger definitions.  (Bug#15110
     (http://bugs.mysql.com/15110))

   * The output of `SHOW TRIGGERS' contained extraneous whitespace.
     (Bug#15103 (http://bugs.mysql.com/15103))

   * Creating a trigger caused a server crash if the table or trigger
     database was not known because no default database had been
     selected.  (Bug#14863 (http://bugs.mysql.com/14863))

   * `InnoDB': Comparison of indexed `VARCHAR CHARACTER SET ucs2
     COLLATE ucs2_bin' columns using `LIKE' could fail.  (Bug#14583
     (http://bugs.mysql.com/14583))

   * A `COMMIT' statement followed by a `ALTER TABLE' statement on a
     BDB table caused server crash.  (Bug#14212
     (http://bugs.mysql.com/14212))

   * An `INSERT ... SELECT' statement between tables in a `MERGE' set
     can return errors when statement involves insert into child table
     from merge table or vice-versa.  (Bug#5390
     (http://bugs.mysql.com/5390))

   * `InnoDB': An `UPDATE' statement with no index column in the `WHERE'
     condition locked all the rows in the table.  (Bug#3300
     (http://bugs.mysql.com/3300))


File: manual.info,  Node: news-5-1-4,  Next: news-5-1-3,  Prev: news-5-1-5,  Up: news-5-1-x

C.1.26 Changes in MySQL 5.1.4 (21 December 2005)
------------------------------------------------

Functionality added or changed:

   * Added the `--server-id' option to `mysqlbinlog' to enable only
     those events created by the server having the given server ID to be
     extracted.  (Bug#15485 (http://bugs.mysql.com/15485))

   * It is now possible to build the server such that `MyISAM' tables
     can support up to 128 keys rather than the standard 64. This can
     be done by configuring the build using the option
     `--with-max-indexes=N ', where N<=128 is the maximum number of
     indexes to permit per table.  (Bug#10932
     (http://bugs.mysql.com/10932))

   * Added the `myisam_use_mmap' system variable.

   * Added the `--bdb-data-direct' and `--bdb-log-direct' server
     options.

   * Added the `mysqlslap' program, which is designed to emulate client
     load for a MySQL server and report the timing of each stage. It
     works as if multiple clients are accessing the server.

   * The bundled `BDB' library was upgraded to version 4.4.16.

   * Added the `cp1250_polish_ci' collation for the `cp1250' character
     set.

Bugs fixed:

   * *MySQL Cluster*: The `--ndb' option for `perror' did not function.
     (Bug#15486 (http://bugs.mysql.com/15486))

   * *MySQL Cluster*: Using `ORDER BY PRIMARY_KEY_COLUMN' when
     selecting from a table having the primary key on a `VARCHAR'
     column caused a forced shutdown of the cluster.  (Bug#15240
     (http://bugs.mysql.com/15240), Bug#15682
     (http://bugs.mysql.com/15682), Bug#14828
     (http://bugs.mysql.com/14828), Bug#15517
     (http://bugs.mysql.com/15517))

   * Server could not be built on default Debian systems with BDB
     enabled.  (Bug#15734 (http://bugs.mysql.com/15734))

   * `SHOW ENGINES' output showed the `FEDERATED' engine as `DISABLED'
     even for builds with `FEDERATED' support.  (Bug#15559
     (http://bugs.mysql.com/15559))

   * `BDB': A `DELETE', `INSERT', or `UPDATE' of a `BDB' table could
     cause the server to crash where the query contained a subquery
     using an index read.  (Bug#15536 (http://bugs.mysql.com/15536))

   * It was not possible to reorganize a partition reusing a discarded
     partition name.

     Now, for example, you can create a table such as this one:

          CREATE TABLE t1 (a INT)
              PARTITION BY RANGE (a) (
                PARTITION p0 VALUES LESS THAN (10),
                PARTITION p1 VALUES LESS THAN (20),
                PARTITION p2 VALUES LESS THAN MAXVALUE
              );

     and then repartition it as shown here:

          ALTER TABLE t1 REORGANIZE PARTITION p2 INTO (
              PARTITION p2 VALUES LESS THAN (30)
          );

     Previously, attempting to do so would produce the error `All
     partitions must have unique names in the table' .  (Bug#15521
     (http://bugs.mysql.com/15521))

   * The `BLACKHOLE' storage engine did not handle transactions
     properly: Rolled-back transactions were written to the binary log.
     Now they ae not.  (Bug#15406 (http://bugs.mysql.com/15406))

   * A left join on a column that having a `NULL' value could cause the
     server to crash.  (Bug#15268 (http://bugs.mysql.com/15268))

   * Selecting from a view processed with the temptable algorithm
     caused a server crash if the query cache was enabled.  (Bug#15119
     (http://bugs.mysql.com/15119))

   * Creating a view that referenced a stored function that selected
     from a view caused a crash upon selection from the view.
     (Bug#15096 (http://bugs.mysql.com/15096))

   * Multiple-table update operations were counting updates and not
     updated rows. As a result, if a row had several updates it was
     counted several times for the `rows matched' value but updated
     only once.  (Bug#15028 (http://bugs.mysql.com/15028))

   * `ROW_COUNT()' returned an incorrect result after `EXECUTE' of a
     prepared statement.  (Bug#14956 (http://bugs.mysql.com/14956))

   * `ANALYZE TABLE' did not properly update table statistics for a
     `MyISAM' table with a `FULLTEXT' index containing stopwords, so a
     subsequent `ANALYZE TABLE' would not recognize the table as having
     already been analyzed.  (Bug#14902 (http://bugs.mysql.com/14902))

   * Creating a view within a stored procedure could result in an out
     of memory error or a server crash.  (Bug#14885
     (http://bugs.mysql.com/14885))

   * `SELECT' queries that began with an opening parenthesis were not
     being placed in the query cache.  (Bug#14652
     (http://bugs.mysql.com/14652))

   * Space truncation was being ignored when inserting into `BINARY' or
     `VARBINARY' columns. Now space truncation results in a warning, or
     an error in strict mode.  (Bug#14299 (http://bugs.mysql.com/14299))

   * The maximum value of `MAX_ROWS' was handled incorrectly on 64-bit
     systems.  (Bug#14155 (http://bugs.mysql.com/14155))

   * For binary string data types, `mysqldump --hex-blob' produced an
     illegal output value of `0x' rather than `'''.  (Bug#13318
     (http://bugs.mysql.com/13318))

   * Some comparisons for the `IN()' operator were inconsistent with
     equivalent comparisons for the `=' operator.  (Bug#12612
     (http://bugs.mysql.com/12612))

   * Attempts to assign `NULL' to a `NOT NULL' column in strict mode
     now result in a message of `Column 'COL_NAME' cannot be null',
     rather than `Column set to default value; NULL supplied to NOT
     NULL column 'COL_NAME' at row N'.  (Bug#11491
     (http://bugs.mysql.com/11491))

   * `SHOW CREATE DATABASE' was sometimes refused when the client had
     privileges for the database.  (Bug#9785
     (http://bugs.mysql.com/9785))

   * Invalid casts to `DATE' values now result in a message of
     `Incorrect datetime value', rather than `Truncated incorrect
     datetime value'.  (Bug#8294 (http://bugs.mysql.com/8294))

   * `mysql' ignored the `MYSQL_TCP_PORT' environment variable.
     (Bug#5792 (http://bugs.mysql.com/5792))


File: manual.info,  Node: news-5-1-3,  Next: news-5-1-2,  Prev: news-5-1-4,  Up: news-5-1-x

C.1.27 Changes in MySQL 5.1.3 (29 November 2005)
------------------------------------------------

Functionality added or changed:

   * *Plugin API*: *Incompatible Change*: MySQL 5.1 adds support for a
     very flexible plugin API that enables loading and unloading of
     various components at runtime, without restarting the server.
     Although the work on this is not finished yet, _plugin full-text
     parsers_ are a first step in this direction. This allows users to
     implement their own input filter on the indexed text, enabling
     full-text search capability on arbitrary data such as PDF files or
     other document formats. A pre-parser full-text plugin performs the
     actual parsing and extraction of the text and hands it over to the
     built-in MySQL full-text search. (Author: Sergey Vojtovich)

     The plugin API requires the `mysql.plugin' table. When upgrading
     from an older version of MySQL, you should run the
     `mysql_fix_privilege_tables' command to create this table. See
     *Note mysql-fix-privilege-tables::.

     Plugins are installed in the directory named by the `plugin_dir'
     system variable. This variable also controls the location from
     which the server loads user-defined functions (UDFs), which is a
     change from earlier versions of MySQL. That is, all UDF library
     files now must be installed in the plugin directory. When
     upgrading from an older version of MySQL, you must migrate your
     UDF files to the plugin directory.

   * *Incompatible Change*: Renamed the `table_cache' system variable to
     `table_open_cache'. Any scripts that refer to `table_cache' should
     be updated to use the new name.

   * *MySQL Cluster*: `VARCHAR' columns used in MySQL Cluster tables
     are now variable-sized; that is, they now only allocate as much
     space as required to store the data. Previously, a `VARCHAR(N)'
     column allocated n+2 bytes (aligned to 4 bytes), regardless of
     whether the actual inserted value required that much space. (In
     other words, a `VARCHAR' column always required the same, fixed,
     amount of storage as a `CHAR' column of the same size.)

   * *Partitioning*: allows distributing portions of individual tables
     across a filesystem, according to rules which can be set when the
     table is created. In effect, different portions of a table are
     stored as separate tables in different locations, but from the user
     point of view, the partitioned table is still a single table.  See
     *Note partitioning::, for further information on this
     functionality. (Author: Mikael Ronstro"m)

   * `RAND()' no longer allows non-constant initializers. (Prior to
     MySQL 5.1.3, the effect of non-constant initializers is undefined.)
     (Bug#6172 (http://bugs.mysql.com/6172))

   * Added the `table_definition_cache' system variable. If you use a
     large number of tables, you can create a large table definition
     cache to speed up opening of tables. The table definition cache
     takes less space and does not use file descriptors, unlike the
     normal table cache.

   * `SET INSTANCE_NAME.  OPTION_NAME=OPTION_VALUE ' sets an option to
     the specified value and writes it to the config file See *Note
     instance-manager::, for more details on these new commands.
     (Author: Petr Chardin)

   * `SHOW INSTANCE_NAME LOG FILES' provides a listing of all log files
     used by the instance. (Author: Petr Chardin)

   * Added the `SHOW AUTHORS' statement.

   * Fast `ALTER TABLE': Operations that change only table metadata and
     not table data do not require a temporary table to be used, which
     improves performance. For example, renaming a column changes only
     the `.frm' file and no longer uses a temporary table.

   * *The Instance Manager (IM)* now has some additional functionality:

        * `SHOW INSTANCE_NAME LOG FILES' provides a listing of all log
          files used by the instance. (Author: Petr Chardin)

        * `SHOW INSTANCE_NAME LOG {ERROR | SLOW | GENERAL} SIZE '
          retrieves a part of the specified log file.  (Author: Petr
          Chardin)

        * `SET INSTANCE_NAME.  OPTION_NAME=OPTION_VALUE ' sets an
          option to the specified value and writes it to the config
          file See *Note instance-manager::, for more details on these
          new commands. (Author: Petr Chardin)

   * `SHOW INSTANCE_NAME LOG {ERROR | SLOW | GENERAL} SIZE ' retrieves
     a part of the specified log file. (Author: Petr Chardin)

   * Added the `SHOW FUNCTION CODE' and `SHOW PROCEDURE CODE'
     statements (available only for servers that have been built with
     debugging support).  See *Note show-procedure-code::.

   * The performance of boolean full-text searches (using the `+'
     Operator) has been improved. See *Note fulltext-search::, for more
     details about full-text searching. (Author: Sergey Vojtovich)

Bugs fixed:

   * `RESET MASTER' failed to delete log files on Windows. One
     consequence of this change is that server opens the general query
     and slow log files in shared mode, so now they can be renamed
     while the server has them open (something not true in previous
     versions).  (Bug#13377 (http://bugs.mysql.com/13377))

   * Set functions could not be aggregated in outer subqueries.
     (Bug#12762 (http://bugs.mysql.com/12762))


File: manual.info,  Node: news-5-1-2,  Next: news-5-1-1,  Prev: news-5-1-3,  Up: news-5-1-x

C.1.28 Changes in MySQL 5.1.2 (Not released)
--------------------------------------------

Functionality added or changed:

   * Added the `bdb_cache_parts' and `bdb_region_size' system
     variables, and allowed `bdb_cache_size' to be larger than 4GB on
     systems that support it.  (Bug#14895 (http://bugs.mysql.com/14895))

   * Added `MAXLOCKS', `MINLOCKS', `MAXWRITE', and `MINWRITE' as
     allowable values of the `--bdb-lock-detect' option.  (Bug#14876
     (http://bugs.mysql.com/14876))

   * Added `--replace' to `mysqldump'. This option uses `REPLACE INTO',
     rather than `INSERT INTO', when writing the dumpfile.

   * Added `Transactions', `XA', and `Savepoints' columns to `SHOW
     ENGINES' output.

Bugs fixed:

   * Foreign keys were not properly enforced in `TEMPORARY' tables.
     Foreign keys now are disallowed in `TEMPORARY' tables.  (Bug#12084
     (http://bugs.mysql.com/12084))


File: manual.info,  Node: news-5-1-1,  Prev: news-5-1-2,  Up: news-5-1-x

C.1.29 Changes in MySQL 5.1.1 (Not released)
--------------------------------------------

Bugs fixed:

   * *Partitioning*: *MySQL Cluster*: Specifying the wrong nodegroup in
     a `CREATE TABLE' statement using partitioning would lead to the
     table name being locked after the statement failed (that is, the
     table name could not be re-used).  (Bug#12114
     (http://bugs.mysql.com/12114))

   * Using `ORDER BY' in a query with a partitioned table on a 64-bit
     operating system could crash the server.  (Bug#12116
     (http://bugs.mysql.com/12116))

   * Performing a `CREATE TABLE' statement with a `PARTITION BY' clause
     in a prepared statement could crash a server running in debug mode.
     (Bug#12097 (http://bugs.mysql.com/12097))

   * When two threads competed for the same table, a deadlock could
     occur if one thread also had a lock on another table through `LOCK
     TABLES' and the thread was attempting to remove the table in some
     manner while the other thread tried to place locks on both tables.
     (Bug#10600 (http://bugs.mysql.com/10600))


File: manual.info,  Node: myodbc-news,  Next: connector-net-news,  Prev: news-5-1-x,  Up: news

C.2 MySQL Connector/ODBC (MyODBC) Change History
================================================

* Menu:

* myodbc-news-5-1-5::            Changes in MySQL Connector/ODBC 5.1.5 (Not yet released)
* myodbc-news-5-1-4::            Changes in MySQL Connector/ODBC 5.1.4 (15 April 2008)
* myodbc-news-5-1-3::            Changes in MySQL Connector/ODBC 5.1.3 (26 March 2008)
* myodbc-news-5-1-2::            Changes in MySQL Connector/ODBC 5.1.2 (13 February 2008)
* myodbc-news-5-1-1::            Changes in MySQL Connector/ODBC 5.1.1 (13 December 2007)
* myodbc-news-5-1-0::            Changes in MySQL Connector/ODBC 5.1.0 (10 September 2007)
* myodbc-news-5-0-12::           Changes in MySQL Connector/ODBC 5.0.12 (Never released)
* myodbc-news-5-0-11::           Changes in MySQL Connector/ODBC 5.0.11 (31 January 2007)
* myodbc-news-5-0-10::           Changes in MySQL Connector/ODBC 5.0.10 (14 December 2006)
* myodbc-news-5-0-9::            Changes in MySQL Connector/ODBC 5.0.9 (22 November 2006)
* myodbc-news-5-0-8::            Changes in MySQL Connector/ODBC 5.0.8 (17 November 2006)
* myodbc-news-5-0-7::            Changes in MySQL Connector/ODBC 5.0.7 (08 November 2006)
* myodbc-news-5-0-6::            Changes in MySQL Connector/ODBC 5.0.6 (03 November 2006)
* myodbc-news-5-0-5::            Changes in MySQL Connector/ODBC 5.0.5 (17 October 2006)
* myodbc-news-5-0-3::            Changes in Connector/ODBC 5.0.3 (Connector/ODBC 5.0 Alpha 3) (20 June 2006)
* myodbc-news-5-0-2::            Changes in Connector/ODBC 5.0.2 (Never released)
* myodbc-news-5-0-1::            Changes in Connector/ODBC 5.0.1 (Connector/ODBC 5.0 Alpha 2) (05 June 2006)
* myodbc-news-3-51-26::          Changes in MySQL Connector/ODBC 3.51.26 (07 July 2008)
* myodbc-news-3-51-25::          Changes in MySQL Connector/ODBC 3.51.25 (11 April 2008)
* myodbc-news-3-51-24::          Changes in MySQL Connector/ODBC 3.51.24 (14 March 2008)
* myodbc-news-3-51-23::          Changes in MySQL Connector/ODBC 3.51.23 (09 January 2008)
* myodbc-news-3-51-22::          Changes in MySQL Connector/ODBC 3.51.22 (13 November 2007)
* myodbc-news-3-51-21::          Changes in MySQL Connector/ODBC 3.51.21 (08 October 2007)
* myodbc-news-3-51-20::          Changes in MySQL Connector/ODBC 3.51.20 (10 September 2007)
* myodbc-news-3-51-19::          Changes in MySQL Connector/ODBC 3.51.19 (10 August 2007)
* myodbc-news-3-51-18::          Changes in MySQL Connector/ODBC 3.51.18 (08 August 2007)
* myodbc-news-3-51-17::          Changes in MySQL Connector/ODBC 3.51.17 (14 July 2007)
* myodbc-news-3-51-16::          Changes in MySQL Connector/ODBC 3.51.16 (14 June 2007)
* myodbc-news-3-51-15::          Changes in MySQL Connector/ODBC 3.51.15 (07 May 2007)
* myodbc-news-3-51-14::          Changes in MySQL Connector/ODBC 3.51.14 (08 March 2007)
* myodbc-news-3-51-13::          Changes in MySQL Connector/ODBC 3.51.13 (Never released)
* myodbc-news-3-51-12::          Changes in MySQL Connector/ODBC 3.51.12 (11 Febrauary 2005)
* myodbc-news-3-51-11::          Changes in MySQL Connector/ODBC 3.51.11 (28 January 2005)


File: manual.info,  Node: myodbc-news-5-1-5,  Next: myodbc-news-5-1-4,  Prev: myodbc-news,  Up: myodbc-news

C.2.1 Changes in MySQL Connector/ODBC 5.1.5 (Not yet released)
--------------------------------------------------------------

Bugs fixed:

   * ODBC `TIMESTAMP' string format is not handled properly by the
     MyODBC driver. When passing a `TIMESTAMP' or `DATE' to MyODBC, in
     the ODBC format: {d <date>} or {ts <timestamp>}, the string that
     represents this is copied once into the SQL statement, and then
     added again, as an escaped string.  (Bug#37342
     (http://bugs.mysql.com/37342))

   * `SQLDriverConnect' does not return `SQL_NO_DATA' on cancel. The
     ODBC documentation specifies that this method should return
     `SQL_NO_DATA' when the user cancels the dialog to connect. The
     connector, however, returns `SQL_ERROR'.  (Bug#36293
     (http://bugs.mysql.com/36293))

   * Assigning a string longer than 67 characters to the `TableType'
     parameter resulted in a buffer overrun when the `SQLTables()'
     function was called.  (Bug#36275 (http://bugs.mysql.com/36275))

   * The ODBC connector randomly uses logon information stored in
     `odbc-profile', or prompts the user for connection information and
     ignores any settings stored in `odbc-profile'.  (Bug#36203
     (http://bugs.mysql.com/36203))

   * After having successfully established a connection, a crash occurs
     when calling `SQLProcedures()' followed by `SQLFreeStmt()', using
     the ODBC C API.  (Bug#36069 (http://bugs.mysql.com/36069))


File: manual.info,  Node: myodbc-news-5-1-4,  Next: myodbc-news-5-1-3,  Prev: myodbc-news-5-1-5,  Up: myodbc-news

C.2.2 Changes in MySQL Connector/ODBC 5.1.4 (15 April 2008)
-----------------------------------------------------------

Bugs fixed:

   * Wrong result obtained when using `sum()' on a `decimal(8,2)' field
     type.  (Bug#35920 (http://bugs.mysql.com/35920))

   * The driver installer could not create a new DSN if many other
     drivers were already installed.  (Bug#35776
     (http://bugs.mysql.com/35776))

   * The `SQLColAttribute()' function returned `SQL_TRUE' when querying
     the `SQL_DESC_FIXED_PREC_SCALE (SQL_COLUMN_MONEY)' attribute of a
     `DECIMAL' column. Previously, the correct value of `SQL_FALSE' was
     returned; this is now again the case.  (Bug#35581
     (http://bugs.mysql.com/35581))

   * On Linux, `SQLGetDiagRec()' returned `SQL_SUCCESS' in cases when
     it should have returned `SQL_NO_DATA'.  (Bug#33910
     (http://bugs.mysql.com/33910))

   * The driver crashes ODBC Administrator on attempting to add a new
     DSN.  (Bug#32057 (http://bugs.mysql.com/32057))


File: manual.info,  Node: myodbc-news-5-1-3,  Next: myodbc-news-5-1-2,  Prev: myodbc-news-5-1-4,  Up: myodbc-news

C.2.3 Changes in MySQL Connector/ODBC 5.1.3 (26 March 2008)
-----------------------------------------------------------

Platform specific notes:

   * *Important Change*: You must uninstall previous 5.1.x editions of
     Connector/ODBC before installing the new version.

   * The HP-UX 11.23 IA64 binary package does not include the GUI bits
     because of problems building Qt on that platform.

   * There is no binary package for Mac OS X on 64-bit PowerPC because
     Apple does not currently provide a 64-bit PowerPC version of iODBC.

   * The installer for 64-bit Windows installs both the 32-bit and
     64-bit driver. Please note that Microsoft does not yet supply a
     64-bit bridge from ADO to ODBC.

Bugs fixed:

   * *Important Change*: In previous versions, the SSL certificate
     would automatically be verified when used as part of the
     Connector/ODBC connection. The default mode is now to ignore the
     verificate of certificates. To enforce verification of the SSL
     certificate during connection, use the `SSLVERIFY' DSN parameter,
     setting the value to 1.  (Bug#29955 (http://bugs.mysql.com/29955),
     Bug#34648 (http://bugs.mysql.com/34648))

   * Inserting characters to a UTF8 table using surrogate pairs would
     fail and insert invalid data.  (Bug#34672
     (http://bugs.mysql.com/34672))

   * Installation of Connector/ODBC would fail because it was unable to
     uninstall a previous installed version. The file being requested
     would match an older release version than any installed version of
     the connector.  (Bug#34522 (http://bugs.mysql.com/34522))

   * Using `SqlGetData' in combination with `SQL_C_WCHAR' would return
     overlapping data.  (Bug#34429 (http://bugs.mysql.com/34429))

   * Descriptor records were not cleared correctly when calling
     `SQLFreeStmt(SQL_UNBIND)'.  (Bug#34271
     (http://bugs.mysql.com/34271))

   * The dropdown selection for databases on a server when creating a
     DSN was too small. The list size now automatically adjusts up to a
     maximum size of 20 potential databases.  (Bug#33918
     (http://bugs.mysql.com/33918))

   * Microsoft Access would be unable to use
     `DBEngine.RegisterDatabase' to create a DSN using the
     Connector/ODBC driver.  (Bug#33825 (http://bugs.mysql.com/33825))

   * Connector/ODBC erroneously reported that it supported the `CAST()'
     and `CONVERT()' ODBC functions for parsing values in SQL
     statements, which could lead to bad SQL generation during a query.
     (Bug#33808 (http://bugs.mysql.com/33808))

   * Using a linked table in Access 2003 where the table has a `BIGINT'
     column as the first column in the table, and is configured as the
     primary key, shows `#DELETED' for all rows of the table.
     (Bug#24535 (http://bugs.mysql.com/24535))

   * Updating a `RecordSet' when the query involves a `BLOB' field
     would fail.  (Bug#19065 (http://bugs.mysql.com/19065))


File: manual.info,  Node: myodbc-news-5-1-2,  Next: myodbc-news-5-1-1,  Prev: myodbc-news-5-1-3,  Up: myodbc-news

C.2.4 Changes in MySQL Connector/ODBC 5.1.2 (13 February 2008)
--------------------------------------------------------------

MySQL Connector/ODBC 5.1.2-beta, a new version of the ODBC driver for
the MySQL database management system, has been released. This release
is the second beta (feature-complete) release of the new 5.1 series and
is suitable for use with any MySQL server version since MySQL 4.1,
including MySQL 5.0, 5.1, and 6.0. (It will not work with 4.0 or
earlier releases.)

Keep in mind that this is a beta release, and as with any other
pre-production release, caution should be taken when installing on
production level systems or systems with critical data.

Platform specific notes:

   * The HP-UX 11.23 IA64 binary package does not include the GUI bits
     because of problems building Qt on that platform.

   * There is no binary package for Mac OS X on 64-bit PowerPC because
     Apple does not currently provide a 64-bit PowerPC version of iODBC.

   * The installer for 64-bit Windows installs both the 32-bit and
     64-bit driver. Please note that Microsoft does not yet supply a
     64-bit bridge from ADO to ODBC.

   * Due to differences with the installation process used on Windows
     and potential registry corruption, it is recommended that
     uninstall any existing versions of Connector/ODBC 5.1.x before
     upgrading.

     See also Bug#34571 (http://bugs.mysql.com/34571)

Functionality added or changed:

   * Explicit descriptors are implemented.  (Bug#32064
     (http://bugs.mysql.com/32064))

   * A full implementation of SQLForeignKeys based on the information
     available from INFORMATION_SCHEMA in 5.0 and later versions of the
     server has been implemented.

   * Changed `SQL_ATTR_PARAMSET_SIZE' to return an error until support
     for it is implemented.

   * Disabled `MYSQL_OPT_SSL_VERIFY_SERVER_CERT' when using an SSL
     connection.

   * `SQLForeignKeys' uses `INFORMATION_SCHEMA' when it is available on
     the server, which allows more complete information to be returned.

Bugs fixed:

   * The `SSLCIPHER' option would be incorrectly recorded within the
     SSL configuration on Windows.  (Bug#33897
     (http://bugs.mysql.com/33897))

   * Within the GUI interface, when connecting to a MySQL server on a
     non-standard port, the connection test within the GUI would fail.
     The issue was related to incorrect parsing of numeric values
     within the DSN when the option was not configured as the last
     parameter within the DSN.  (Bug#33822
     (http://bugs.mysql.com/33822))

   * Specifying a non-existent database name within the GUI dialog
     would result in an empty list, not an error.  (Bug#33615
     (http://bugs.mysql.com/33615))

   * When deleting rows from a static cursor, the cursor position would
     be incorrectly reported.  (Bug#33388 (http://bugs.mysql.com/33388))

   * `SQLGetInfo()' reported characters for `SQL_SPECIAL_CHARACTERS'
     that were not encoded correctly.  (Bug#33130
     (http://bugs.mysql.com/33130))

   * Retrieving data from a `BLOB' column would fail within
     `SQLGetData'when the target data type was `SQL_C_WCHAR' due to
     incorrect handling of the character buffer.  (Bug#32684
     (http://bugs.mysql.com/32684))

   * Renaming an existing DSN entry would create a new entry with the
     new name without deleting the old entry.  (Bug#31165
     (http://bugs.mysql.com/31165))

   * Reading a `TEXT' column that had been used to store UTF8 data
     would result in the wrong information being returned during a
     query.  (Bug#28617 (http://bugs.mysql.com/28617))

   * `SQLForeignKeys' would return an empty string for the schema
     columns instead of `NULL'.  (Bug#19923
     (http://bugs.mysql.com/19923))

   * When accessing column data, `FLAG_COLUMN_SIZE_S32' did not limit
     the octet length or display size reported for fields, causing
     problems with Microsoft Visual FoxPro.

     The list of ODBC functions that could have caused failures in
     Microsoft software when retrieving the length of `LONGBLOB' or
     `LONGTEXT' columns includes:

        * `SQLColumns'

        * `SQLColAttribute'

        * `SQLColAttributes'

        * `SQLDescribeCol'

        * `SQLSpecialColumns' (theoretically can have the same problem)

     (Bug#12805 (http://bugs.mysql.com/12805), Bug#30890
     (http://bugs.mysql.com/30890))

   * Dynamic cursors on statements with parameters were not supported.
     (Bug#11846 (http://bugs.mysql.com/11846))

   * Evaluating a simple numeric expression when using the OLEDB for
     ODBC provider and ADO would return an error, instead of the result.
     (Bug#10128 (http://bugs.mysql.com/10128))

   * Adding or updating a row using `SQLSetPos()' on a result set with
     aliased columns would fail.  (Bug#6157
     (http://bugs.mysql.com/6157))


File: manual.info,  Node: myodbc-news-5-1-1,  Next: myodbc-news-5-1-0,  Prev: myodbc-news-5-1-2,  Up: myodbc-news

C.2.5 Changes in MySQL Connector/ODBC 5.1.1 (13 December 2007)
--------------------------------------------------------------

MySQL Connector/ODBC 5.1.1-beta, a new version of the ODBC driver for
the MySQL database management system, has been released. This release
is the first beta (feature-complete) release of the new 5.1 series and
is suitable for use with any MySQL server version since MySQL 4.1,
including MySQL 5.0, 5.1, and 6.0. (It will not work with 4.0 or
earlier releases.)

Keep in mind that this is a beta release, and as with any other
pre-production release, caution should be taken when installing on
production level systems or systems with critical data.

Includes changes from *Note Connector/ODBC 3.51.21:
myodbc-news-3-51-21. and *Note 3.51.22: myodbc-news-3-51-22.

Built using MySQL 5.0.52.

Platform specific notes:

   * The HP-UX 11.23 IA64 binary package does not include the GUI bits
     because of problems building Qt on that platform.

   * There is no binary package for Mac OS X on 64-bit PowerPC because
     Apple does not currently provide a 64-bit PowerPC version of iODBC.

   * The installer for 64-bit Windows installs both the 32-bit and
     64-bit driver. Please note that Microsoft does not yet supply a
     64-bit bridge from ADO to ODBC.

   * Due to differences with the installation process used on Windows
     and potential registry corruption, it is recommended that
     uninstall any existing versions of Connector/ODBC 5.1.x before
     upgrading.

     See also Bug#34571 (http://bugs.mysql.com/34571)

Functionality added or changed:

   * *Incompatible Change*: Replaced myodbc3i (now myodbc-installer)
     with Connector/ODBC 5.0 version.

   * *Incompatible Change*: Removed monitor (myodbc3m) and dsn-editor
     (myodbc3c).

   * *Incompatible Change*: Disallow `SET NAMES' in initial statement
     and in executed statements.

   * A wrapper for the `SQLGetPrivateProfileStringW()' function, which
     is required for Unicode support, has been created. This function
     is missing from the unixODBC driver manager.  (Bug#32685
     (http://bugs.mysql.com/32685))

   * Added MSI installer for Windows 64-bit.  (Bug#31510
     (http://bugs.mysql.com/31510))

   * Implemented support for `SQLCancel()'.  (Bug#15601
     (http://bugs.mysql.com/15601))

   * Added support for `SQL_NUMERIC_STRUCT'.  (Bug#3028
     (http://bugs.mysql.com/3028), Bug#24920
     (http://bugs.mysql.com/24920))

   * Removed non-threadsafe configuration of the driver. The driver is
     now always built against the threadsafe version of libmysql.

   * Implemented native Windows setup library

   * Replaced the internal library which handles creation and loading
     of DSN information. The new library, which was originally a part
     of Connector/ODBC 5.0, supports Unicode option values.

   * The Windows installer now places files in a subdirectory of the
     `Program Files' directory instead of the Windows system directory.

Bugs fixed:

   * The `SET NAMES' statement has been disabled because it causes
     problems in the ODBC driver when determining the current client
     character set.  (Bug#32596 (http://bugs.mysql.com/32596))

   * `SQLDescribeColW' returned UTF-8 column as `SQL_VARCHAR' instead of
     `SQL_WVARCHAR'.  (Bug#32161 (http://bugs.mysql.com/32161))

   * ADO was unable to open record set using dynamic cursor.
     (Bug#32014 (http://bugs.mysql.com/32014))

   * ADO applications would not open a `RecordSet' that contained a
     `DECIMAL' field.  (Bug#31720 (http://bugs.mysql.com/31720))

   * Memory usage would increase considerably.  (Bug#31115
     (http://bugs.mysql.com/31115))

   * SQL statements are limited to 64KB.  (Bug#30983
     (http://bugs.mysql.com/30983), Bug#30984
     (http://bugs.mysql.com/30984))

   * `SQLSetPos' with `SQL_DELETE' advances dynamic cursor incorrectly.
     (Bug#29765 (http://bugs.mysql.com/29765))

   * Using an ODBC prepared statement with bound columns would produce
     an empty result set when called immediately after inserting a row
     into a table.  (Bug#29239 (http://bugs.mysql.com/29239))

   * ADO Not possible to update a client side cursor.  (Bug#27961
     (http://bugs.mysql.com/27961))

   * Recordset `Update()' fails when using `adUseClient' cursor.
     (Bug#26985 (http://bugs.mysql.com/26985))

   * Connector/ODBC would fail to connect to the server if the password
     contained certain characters, including the semicolon and other
     punctuation marks.  (Bug#16178 (http://bugs.mysql.com/16178))

   * Fixed `SQL_ATTR_PARAM_BIND_OFFSET', and fixed row offsets to work
     with updatable cursors.

   * `SQLSetConnectAttr()' did not clear previous errors, possibly
     confusing `SQLError()'.

   * `SQLError()' incorrectly cleared the error information, making it
     unavailable from subsequent calls to `SQLGetDiagRec()'.

   * NULL pointers passed to `SQLGetInfo()' could result in a crash.

   * `SQL_ODBC_SQL_CONFORMANCE' was not handled by `SQLGetInfo()'.

   * `SQLCopyDesc()' did not correctly copy all records.

   * Diagnostics were not correctly cleared on connection and
     environment handles.


File: manual.info,  Node: myodbc-news-5-1-0,  Next: myodbc-news-5-0-12,  Prev: myodbc-news-5-1-1,  Up: myodbc-news

C.2.6 Changes in MySQL Connector/ODBC 5.1.0 (10 September 2007)
---------------------------------------------------------------

This release is the first of the new 5.1 series and is suitable for use
with any MySQL server version since MySQL 4.1, including MySQL 5.0,
5.1, and 6.0. (It will not work with 4.0 or earlier releases.)

Keep in mind that this is a alpha release, and as with any other
pre-production release, caution should be taken when installing on
production level systems or systems with critical data. Not all of the
features planned for the final Connector/ODBC 5.1 release are
implemented.

Functionality is based on Connector/ODBC 3.51.20.

Platform specific notes:

   * The HP-UX 11.23 IA64 binary package does not include the GUI bits
     because of problems building Qt on that platform.

   * There is no binary package for Mac OS X on 64-bit PowerPC because
     Apple does not currently provide a 64-bit PowerPC version of iODBC.

   * There are no installer packages for Microsoft Windows x64 Edition.

   * Due to differences with the installation process used on Windows
     and potential registry corruption, it is recommended that
     uninstall any existing versions of Connector/ODBC 5.1.x before
     upgrading.

     See also Bug#34571 (http://bugs.mysql.com/34571)

Functionality added or changed:

   * Added support for Unicode functions (`SQLConnectW', etc).

   * Added descriptor support (`SQLGetDescField', `SQLGetDescRec', etc).

   * Added support for `SQL_C_WCHAR'.


File: manual.info,  Node: myodbc-news-5-0-12,  Next: myodbc-news-5-0-11,  Prev: myodbc-news-5-1-0,  Up: myodbc-news

C.2.7 Changes in MySQL Connector/ODBC 5.0.12 (Never released)
-------------------------------------------------------------

*Note*:

Development on Connector/ODBC 5.0.x has ceased. New features and
functionality will be incorporated into Connector/ODBC 5.1. See *Note
connector-odbc-roadmap::.

Bugs fixed:

   * Inserting `NULL' values into a `DATETIME' column from Access
     reports an error.  (Bug#27896 (http://bugs.mysql.com/27896))

   * Tables with `TEXT' columns would be incorrectly identified,
     returning an `Unknown SQL type - 65535' error.  (Bug#20127
     (http://bugs.mysql.com/20127))


File: manual.info,  Node: myodbc-news-5-0-11,  Next: myodbc-news-5-0-10,  Prev: myodbc-news-5-0-12,  Up: myodbc-news

C.2.8 Changes in MySQL Connector/ODBC 5.0.11 (31 January 2007)
--------------------------------------------------------------

Functionality added or changed:

   * Added support for ODBC v2 statement options using attributes.

   * Driver now builds and is partially tested under Linux with the
     iODBC driver manager.

Bugs fixed:

   * Connection string parsing for DSN-less connections could fail to
     identify some parameters.  (Bug#25316
     (http://bugs.mysql.com/25316))

   * Updates of `MEMO' or `TEXT' columns from within Microsoft Access
     would fail.  (Bug#25263 (http://bugs.mysql.com/25263))

   * Transaction support has been added and tested.  (Bug#25045
     (http://bugs.mysql.com/25045))

   * Internal function, `my_setpos_delete_ignore()' could cause a crash.
     (Bug#22796 (http://bugs.mysql.com/22796))

   * Fixed occasional mis-handling of the `SQL_NUMERIC_C' type.

   * Fixed the binding of certain integer types.


File: manual.info,  Node: myodbc-news-5-0-10,  Next: myodbc-news-5-0-9,  Prev: myodbc-news-5-0-11,  Up: myodbc-news

C.2.9 Changes in MySQL Connector/ODBC 5.0.10 (14 December 2006)
---------------------------------------------------------------

Connector/ODBC 5.0.10 is the sixth BETA release.

Functionality added or changed:

   * Significant performance improvement when retrieving large text
     fields in pieces using `SQLGetData()' with a buffer smaller than
     the whole data. Mainly used in Access when fetching very large
     text fields.  (Bug#24876 (http://bugs.mysql.com/24876))

   * Added initial unicode support in data and metadata.  (Bug#24837
     (http://bugs.mysql.com/24837))

   * Added initial support for removing braces when calling stored
     procedures and retrieving result sets from procedure calls.
     (Bug#24485 (http://bugs.mysql.com/24485))

   * Added loose handling of retrieving some diagnostic data.
     (Bug#15782 (http://bugs.mysql.com/15782))

   * Added wide-string type info for `SQLGetTypeInfo()'.

Bugs fixed:

   * Editing DSN no longer crashes ODBC data source administrator.
     (Bug#24675 (http://bugs.mysql.com/24675))

   * String query parameters are new escaped correctly.  (Bug#19078
     (http://bugs.mysql.com/19078))


File: manual.info,  Node: myodbc-news-5-0-9,  Next: myodbc-news-5-0-8,  Prev: myodbc-news-5-0-10,  Up: myodbc-news

C.2.10 Changes in MySQL Connector/ODBC 5.0.9 (22 November 2006)
---------------------------------------------------------------

Connector/ODBC 5.0.9 is the fifth BETA release.

This is an implementation and testing release, and is not designed for
use within a production environment.

Functionality added or changed:

   * Added support for column binding as SQL_NUMBERIC_STRUCT.

   * Added recognition of `SQL_C_SHORT' and `SQL_C_TINYINT' as C types.

Bugs fixed:

   * Fixed wildcard handling of and listing of catalogs and tables in
     `SQLTables'.

   * Added limit of display size when requested via
     `SQLColAttribute'/`SQL_DESC_DISPLAY_SIZE'.

   * Fixed buffer length return for SQLDriverConnect.

   * ODBC v2 behaviour in driver now supports ODBC v3 date/time types
     (since DriverManager maps them).

   * Catch use of `SQL_ATTR_PARAMSET_SIZE' and report error until we
     fully support.

   * Fixed statistics to fail if it couldn't be completed.

   * Corrected retrieval multiple field types bit and blob/text.

   * Fixed SQLGetData to clear the NULL indicator correctly during
     multiple calls.


File: manual.info,  Node: myodbc-news-5-0-8,  Next: myodbc-news-5-0-7,  Prev: myodbc-news-5-0-9,  Up: myodbc-news

C.2.11 Changes in MySQL Connector/ODBC 5.0.8 (17 November 2006)
---------------------------------------------------------------

Connector/ODBC 5.0.8 is the fourth BETA release.

This is an implementation and testing release, and is not designed for
use within a production environment.

Functionality added or changed:

   * Also made `SQL_DESC_NAME' only fill in the name if there was a
     data pointer given, otherwise just the length.

   * Fixed display size to be length if max length isn't available.

   * Made distinction between `CHAR'/`BINARY' (and VAR versions).

   * Wildcards now support escaped chars and underscore matching
     (needed to link tables with underscores in access).

Bugs fixed:

   * Fixed binding using `SQL_C_LONG'.

   * Fixed using wrong pointer for `SQL_MAX_DRIVER_CONNECTIONS' in
     `SQLGetInfo'.

   * Set default return to `SQL_SUCCESS' if nothing is done for
     `SQLSpecialColumns'.

   * Fixed MDiagnostic to use correct v2/v3 error codes.

   * Allow SQLDescribeCol to be called to retrieve the length of the
     column name, but not the name itself.

   * Length now used when handling bind parameter (needed in particular
     for `SQL_WCHAR') - this enables updating char data in MS Access.

   * Updated retrieval of descriptor fields to use the right pointer
     types.

   * Fixed hanlding of numeric pointers in SQLColAttribute.

   * Fixed type returned for `MYSQL_TYPE_LONG' to `SQL_INTEGER' instead
     of `SQL_TINYINT'.

   * Fix size return from `SQLDescribeCol'.

   * Fixed string length to chars, not bytes, returned by SQLGetDiagRec.


File: manual.info,  Node: myodbc-news-5-0-7,  Next: myodbc-news-5-0-6,  Prev: myodbc-news-5-0-8,  Up: myodbc-news

C.2.12 Changes in MySQL Connector/ODBC 5.0.7 (08 November 2006)
---------------------------------------------------------------

Connector/ODBC 5.0.7 is the third BETA release.

This is an implementation and testing release, and is not designed for
use within a production environment.

Functionality added or changed:

   * Added support for `SQLStatistics' to `MYODBCShell'.

   * Improved trace/log.

Bugs fixed:

   * SQLBindParameter now handles `SQL_C_DEFAULT'.

   * Corrected incorrect column index within `SQLStatistics'. Many more
     tables can now be linked into MS Access.

   * Fixed `SQLDescribeCol' returning column name length in bytes
     rather than chars.


File: manual.info,  Node: myodbc-news-5-0-6,  Next: myodbc-news-5-0-5,  Prev: myodbc-news-5-0-7,  Up: myodbc-news

C.2.13 Changes in MySQL Connector/ODBC 5.0.6 (03 November 2006)
---------------------------------------------------------------

Connector/ODBC 5.0.6 is the second BETA release.

This is an implementation and testing release, and is not designed for
use within a production environment.

Features, limitations and notes on this release

   * Connector/ODBC supports both `User' and `System' DSNs.

   * Installation is provided in the form of a standard Microsoft
     System Installer (MSI).

   * You no longer have to have Connector/ODBC 3.51 installed before
     installing this version.

Bugs fixed:

   * You no longer have to have Connector/ODBC 3.51 installed before
     installing this version.

   * Connector/ODBC supports both `User' and `System' DSNs.

   * Installation is provided in the form of a standard Microsoft
     System Installer (MSI).


File: manual.info,  Node: myodbc-news-5-0-5,  Next: myodbc-news-5-0-3,  Prev: myodbc-news-5-0-6,  Up: myodbc-news

C.2.14 Changes in MySQL Connector/ODBC 5.0.5 (17 October 2006)
--------------------------------------------------------------

Connector/ODBC 5.0.5 is the first BETA release.

This is an implementation and testing release, and is not designed for
use within a production environment.

You no longer have to have Connector/ODBC 3.51 installed before
installing this version.

Bugs fixed:

   * You no longer have to have Connector/ODBC 3.51 installed before
     installing this version.


File: manual.info,  Node: myodbc-news-5-0-3,  Next: myodbc-news-5-0-2,  Prev: myodbc-news-5-0-5,  Up: myodbc-news

C.2.15 Changes in Connector/ODBC 5.0.3 (Connector/ODBC 5.0 Alpha 3) (20 June 2006)
----------------------------------------------------------------------------------

This is an implementation and testing release, and is not designed for
use within a production environment.

Features, limitations and notes on this release:

   * The following ODBC API functions have been added in this release:

        * `SQLBindParameter'

        * `SQLBindCol'


File: manual.info,  Node: myodbc-news-5-0-2,  Next: myodbc-news-5-0-1,  Prev: myodbc-news-5-0-3,  Up: myodbc-news

C.2.16 Changes in Connector/ODBC 5.0.2 (Never released)
-------------------------------------------------------

Connector/ODBC 5.0.2 was an internal implementation and testing release.


File: manual.info,  Node: myodbc-news-5-0-1,  Next: myodbc-news-3-51-26,  Prev: myodbc-news-5-0-2,  Up: myodbc-news

C.2.17 Changes in Connector/ODBC 5.0.1 (Connector/ODBC 5.0 Alpha 2) (05 June 2006)
----------------------------------------------------------------------------------

Features, limitations and notes on this release:

   * Connector/ODBC 5.0 is Unicode aware.

   * Connector/ODBC is currently limited to basic applications. ADO
     applications and Microsoft Office are not supported.

   * Connector/ODBC must be used with a Driver Manager.

   * The following ODBC API functions are implemented:

        * `SQLAllocHandle'

        * `SQLCloseCursor'

        * `SQLColAttribute'

        * `SQLColumns'

        * `SQLConnect'

        * `SQLCopyDesc'

        * `SQLDisconnect'

        * `SQLExecDirect'

        * `SQLExecute'

        * `SQLFetch'

        * `SQLFreeHandle'

        * `SQLFreeStmt'

        * `SQLGetConnectAttr'

        * `SQLGetData'

        * `SQLGetDescField'

        * `SQLGetDescRec'

        * `SQLGetDiagField'

        * `SQLGetDiagRec'

        * `SQLGetEnvAttr'

        * `SQLGetFunctions'

        * `SQLGetStmtAttr'

        * `SQLGetTypeInfo'

        * `SQLNumResultCols'

        * `SQLPrepare'

        * `SQLRowcount'

        * `SQLTables'

     The following ODBC API function are implemented, but not yet
     support all the available attributes/options:

        * `SQLSetConnectAttr'

        * `SQLSetDescField'

        * `SQLSetDescRec'

        * `SQLSetEnvAttr'

        * `SQLSetStmtAttr'


File: manual.info,  Node: myodbc-news-3-51-26,  Next: myodbc-news-3-51-25,  Prev: myodbc-news-5-0-1,  Up: myodbc-news

C.2.18 Changes in MySQL Connector/ODBC 3.51.26 (07 July 2008)
-------------------------------------------------------------

Functionality added or changed:

   * There is a new connection option, `FLAG_NO_BINARY_RESULT'. When
     set this option disables charset 63 for columns with an empty
     `org_table'.  (Bug#29402 (http://bugs.mysql.com/29402))

Bugs fixed:

   * When an ADOConnection is created and attempts to open a schema with
     ADOConnection.OpenSchema an access violation occurs in
     `myodbc3.dll'.  (Bug#30770 (http://bugs.mysql.com/30770))

   * When `SHOW CREATE TABLE' was invoked and then the field values
     read, the result was truncated and unusable if the table had many
     rows and indexes.  (Bug#24131 (http://bugs.mysql.com/24131))


File: manual.info,  Node: myodbc-news-3-51-25,  Next: myodbc-news-3-51-24,  Prev: myodbc-news-3-51-26,  Up: myodbc-news

C.2.19 Changes in MySQL Connector/ODBC 3.51.25 (11 April 2008)
--------------------------------------------------------------

Bugs fixed:

   * The `SQLColAttribute()' function returned `SQL_TRUE' when querying
     the `SQL_DESC_FIXED_PREC_SCALE (SQL_COLUMN_MONEY)' attribute of a
     `DECIMAL' column. Previously, the correct value of `SQL_FALSE' was
     returned; this is now again the case.  (Bug#35581
     (http://bugs.mysql.com/35581))

   * The driver crashes ODBC Administrator on attempting to add a new
     DSN.  (Bug#32057 (http://bugs.mysql.com/32057))

   * When accessing column data, `FLAG_COLUMN_SIZE_S32' did not limit
     the octet length or display size reported for fields, causing
     problems with Microsoft Visual FoxPro.

     The list of ODBC functions that could have caused failures in
     Microsoft software when retrieving the length of `LONGBLOB' or
     `LONGTEXT' columns includes:

        * `SQLColumns'

        * `SQLColAttribute'

        * `SQLColAttributes'

        * `SQLDescribeCol'

        * `SQLSpecialColumns' (theoretically can have the same problem)

     (Bug#12805 (http://bugs.mysql.com/12805), Bug#30890
     (http://bugs.mysql.com/30890))


File: manual.info,  Node: myodbc-news-3-51-24,  Next: myodbc-news-3-51-23,  Prev: myodbc-news-3-51-25,  Up: myodbc-news

C.2.20 Changes in MySQL Connector/ODBC 3.51.24 (14 March 2008)
--------------------------------------------------------------

Bugs fixed:

   * *Security Enhancement*: Accessing a parameer with the type of
     `SQL_C_CHAR', but with a numeric type and a length of zero, the
     parameter marker would get stropped from the query. In addition, a
     SQL injection was possible if the parameter value had a non-zero
     length and was not numeric, the text would be inserted verbatim.
     (Bug#34575 (http://bugs.mysql.com/34575))

   * *Important Change*: In previous versions, the SSL certificate
     would automatically be verified when used as part of the
     Connector/ODBC connection. The default mode is now to ignore the
     verificate of certificates. To enforce verification of the SSL
     certificate during connection, use the `SSLVERIFY' DSN parameter,
     setting the value to 1.  (Bug#29955 (http://bugs.mysql.com/29955),
     Bug#34648 (http://bugs.mysql.com/34648))

   * When using ADO, the count of parameters in a query would always
     return zero.  (Bug#33298 (http://bugs.mysql.com/33298))

   * Using tables with a single quote or other non-standard characters
     in the table or column names through ODBC would fail.  (Bug#32989
     (http://bugs.mysql.com/32989))

   * When using Crystal Reports, table and column names would be
     truncated to 21 characters, and truncated columns in tables where
     the truncated name was the duplicated would lead to only a single
     column being displayed.  (Bug#32864 (http://bugs.mysql.com/32864))

   * `SQLExtendedFetch()' and `SQLFetchScroll()' ignored the rowset
     size if the `Don't cache result' DSN option was set.  (Bug#32420
     (http://bugs.mysql.com/32420))

   * When using the ODBC `SQL_TXN_READ_COMMITTED' option, 'dirty'
     records would be read from tables as if the option had not been
     applied.  (Bug#31959 (http://bugs.mysql.com/31959))

   * When creating a System DSN using the ODBC Administrator on Mac OS
     X, a User DSN would be created instead. The root cause is a
     problem with the iODBC driver manager used on Mac OS X. The fix
     works around this issue.

     *Note*:

     ODBC Administrator may still be unable to register a System DSN
     unless the `/Library/ODBC/odbc.ini' file has the correct
     permissions. You should ensure that the file is writable by the
     `admin' group.

     (Bug#31495 (http://bugs.mysql.com/31495))

   * Calling `SQLFetch' or `SQLFetchScroll' would return negative data
     lengths when using `SQL_C_WCHAR'.  (Bug#31220
     (http://bugs.mysql.com/31220))

   * `SQLSetParam()' caused memory allocation errors due to driver
     manager's mapping of deprecated functions (buffer length -1).
     (Bug#29871 (http://bugs.mysql.com/29871))

   * Static cursor was unable to be used through ADO when dynamic
     cursors were enabled.  (Bug#27351 (http://bugs.mysql.com/27351))

   * Using `connection.Execute' to create a record set based on a table
     without declaring the cmd option as `adCmdTable' will fail when
     communicating with versions of MySQL 5.0.37 and higher. The issue
     is related to the way that `SQLSTATE' is returned when ADO tries
     to confirm the existence of the target object.  (Bug#27158
     (http://bugs.mysql.com/27158))

   * Updating a `RecordSet' when the query involves a `BLOB' field
     would fail.  (Bug#19065 (http://bugs.mysql.com/19065))

   * With some connections to MySQL databases using Connector/ODBC, the
     connection would mistakenly report 'user cancelled' for accesses
     to the database information.  (Bug#16653
     (http://bugs.mysql.com/16653))


File: manual.info,  Node: myodbc-news-3-51-23,  Next: myodbc-news-3-51-22,  Prev: myodbc-news-3-51-24,  Up: myodbc-news

C.2.21 Changes in MySQL Connector/ODBC 3.51.23 (09 January 2008)
----------------------------------------------------------------

Platform specific notes:

   * The HP-UX 11.23 IA64 binary package does not include the GUI bits
     because of problems building Qt on that platform.

   * There is no binary package for Mac OS X on 64-bit PowerPC because
     Apple does not currently provide a 64-bit PowerPC version of iODBC.

   * There are no installer packages for Microsoft Windows x64 Edition.

Bugs fixed:

   * Connector/ODBC would incorrectly return `SQL_SUCCESS' when
     checking for distributed transaction support.  (Bug#32727
     (http://bugs.mysql.com/32727))

   * When using unixODBC or directly linked applications where the
     thread level is set to less than 3 (within `odbcinst.ini'), a
     thread synchronization issue would lead to an application crash.
     This was because `SQLAllocStmt()' and `SQLFreeStmt()' did not
     synchronize access to the list of statements associated with a
     connection.  (Bug#32587 (http://bugs.mysql.com/32587))

   * Cleaning up environment handles in multithread environments could
     result in a five (or more) second delay.  (Bug#32366
     (http://bugs.mysql.com/32366))

   * Renaming an existing DSN entry would create a new entry with the
     new name without deleting the old entry.  (Bug#31165
     (http://bugs.mysql.com/31165))

   * Setting the default database using the `DefaultDatabase' property
     of an ADO `Connection' object would fail with the error `Provider
     does not support this property'. The `SQLGetInfo()' returned the
     wrong value for `SQL_DATABASE_NAME' when no database was selected.
     (Bug#3780 (http://bugs.mysql.com/3780))


File: manual.info,  Node: myodbc-news-3-51-22,  Next: myodbc-news-3-51-21,  Prev: myodbc-news-3-51-23,  Up: myodbc-news

C.2.22 Changes in MySQL Connector/ODBC 3.51.22 (13 November 2007)
-----------------------------------------------------------------

Functionality added or changed:

   * The workaround for this bug was removed due to the fixes in MySQL
     Server 5.0.48 and 5.1.21.

     This regression was introduced by Bug#10491
     (http://bugs.mysql.com/10491)

Bugs fixed:

   * The `English' locale would be used when formatting floating point
     values. The `C' locale is now used for these values.  (Bug#32294
     (http://bugs.mysql.com/32294))

   * When accessing information about supported operations, the driver
     would return incorrect information about the support for `UNION'.
     (Bug#32253 (http://bugs.mysql.com/32253))

   * Unsigned integer values greater than the maximum value of a signed
     integer would be handled incorrectly.  (Bug#32171
     (http://bugs.mysql.com/32171))

   * The wrong result was returned by `SQLGetData()' when the data was
     an empty string and a zero-sized buffer was specified.  (Bug#30958
     (http://bugs.mysql.com/30958))

   * Added the `FLAG_COLUMN_SIZE_S32' option to limit the reported
     column size to a signed 32-bit integer. This option is
     automatically enabled for ADO applications to provide a work
     around for a bug in ADO.  (Bug#13776 (http://bugs.mysql.com/13776))


File: manual.info,  Node: myodbc-news-3-51-21,  Next: myodbc-news-3-51-20,  Prev: myodbc-news-3-51-22,  Up: myodbc-news

C.2.23 Changes in MySQL Connector/ODBC 3.51.21 (08 October 2007)
----------------------------------------------------------------

Bugs fixed:

   * When using a rowset/cursor and add a new row with a number of
     fields, subsequent rows with fewer fields will include the
     original fields from the previous row in the final `INSERT'
     statement.  (Bug#31246 (http://bugs.mysql.com/31246))

   * Uninitiated memory could be used when C/ODBC internally calls
     `SQLGetFunctions()'.  (Bug#31055 (http://bugs.mysql.com/31055))

   * The wrong `SQL_DESC_LITERAL_PREFIX' would be returned for
     date/time types.  (Bug#31009 (http://bugs.mysql.com/31009))

   * The wrong `COLUMN_SIZE' would be returned by `SQLGetTypeInfo' for
     the TIME columns (`SQL_TYPE_TIME').  (Bug#30939
     (http://bugs.mysql.com/30939))

   * Clicking outside the character set selection box when configuring
     a new DSN could cause the wrong character set to be selected.
     (Bug#30568 (http://bugs.mysql.com/30568))

   * Not specifying a user in the DSN dialog would raise a warning even
     though the parameter is optional.  (Bug#30499
     (http://bugs.mysql.com/30499))

   * `SQLSetParam()' caused memory allocation errors due to driver
     manager's mapping of deprecated functions (buffer length -1).
     (Bug#29871 (http://bugs.mysql.com/29871))

   * When using ADO, a column marked as `AUTO_INCREMENT' could
     incorrectly report that the column allowed `NULL' values. This was
     dur to an issue with `NULLABLE' and `IS_NULLABLE' return values
     from the call to `SQLColumns()'.  (Bug#26108
     (http://bugs.mysql.com/26108))

   * Connector/ODBC would return the wrong the error code when the
     server disconnects the active connection because the configured
     `wait_timeout' has expired. Previously it would return `HY000'.
     Connector/ODBC now correctly returns an `SQLSTATE' of `08S01'.
     (Bug#3456 (http://bugs.mysql.com/3456))


File: manual.info,  Node: myodbc-news-3-51-20,  Next: myodbc-news-3-51-19,  Prev: myodbc-news-3-51-21,  Up: myodbc-news

C.2.24 Changes in MySQL Connector/ODBC 3.51.20 (10 September 2007)
------------------------------------------------------------------

Bugs fixed:

   * Using `FLAG_NO_PROMPT' doesn't suppress the dialogs normally
     handled by `SQLDriverConnect'.  (Bug#30840
     (http://bugs.mysql.com/30840))

   * The specified length of the username and authentication parameters
     to `SQLConnect()' were not being honored.  (Bug#30774
     (http://bugs.mysql.com/30774))

   * The wrong column size was returned for binary data.  (Bug#30547
     (http://bugs.mysql.com/30547))

   * `SQLGetData()' will now always return `SQL_NO_DATA_FOUND' on
     second call when no data left, even if requested size is 0.
     (Bug#30520 (http://bugs.mysql.com/30520))

   * `SQLGetConnectAttr()' did not reflect the connection state
     correctly.  (Bug#14639 (http://bugs.mysql.com/14639))

   * Removed checkbox in setup dialog for `FLAG_FIELD_LENGTH'
     (identified as `Don't Optimize Column Width' within the GUI
     dialog), which was removed from the driver in 3.51.18.


File: manual.info,  Node: myodbc-news-3-51-19,  Next: myodbc-news-3-51-18,  Prev: myodbc-news-3-51-20,  Up: myodbc-news

C.2.25 Changes in MySQL Connector/ODBC 3.51.19 (10 August 2007)
---------------------------------------------------------------

Connector/ODBC 3.51.19 fixes a specific issue with the 3.51.18 release.
For a list of changes in the 3.51.18 release, see *Note
myodbc-news-3-51-18::.

Functionality added or changed:

   * Because of Bug#10491 (http://bugs.mysql.com/10491) in the server,
     character string results were sometimes incorrectly identified as
     `SQL_VARBINARY'. Until this server bug is corrected, the driver
     will identify all variable-length strings as `SQL_VARCHAR'.


File: manual.info,  Node: myodbc-news-3-51-18,  Next: myodbc-news-3-51-17,  Prev: myodbc-news-3-51-19,  Up: myodbc-news

C.2.26 Changes in MySQL Connector/ODBC 3.51.18 (08 August 2007)
---------------------------------------------------------------

Platform specific notes:

   * The HP-UX 11.23 IA64 binary package does not include the GUI bits
     because of problems building Qt on that platform.

   * There is no binary package for Mac OS X on 64-bit PowerPC because
     Apple does not currently provide a 64-bit PowerPC version of iODBC.

   * Binary packages for Sun Solaris are now available as `PKG'
     packages.

   * Binary packages as disk images with installers are now available
     for Mac OS X.

   * A binary package without an installer is available for Microsoft
     Windows x64 Edition. There are no installer packages for Microsoft
     Windows x64 Edition.

Functionality added or changed:

   * *Incompatible Change*: The `FLAG_DEBUG' option was removed.

   * When connecting to a specific database when using a DSN, the
     system tables from the `mysql' database are no longer also
     available. Previously, tables from the mysql database (catalog)
     were listed as `SYSTEM TABLES' by `SQLTables()' even when a
     different catalog was being queried.  (Bug#28662
     (http://bugs.mysql.com/28662))

   * Installed for Mac OS X has been re-instated. The installer
     registers the driver at a system (not user) level and makes it
     possible to create both user and system DSNs using the
     Connector/ODBC driver. The installer also fixes the situation
     where the necessary drivers would bge installed local to the user,
     not globally.  (Bug#15326 (http://bugs.mysql.com/15326), Bug#10444
     (http://bugs.mysql.com/10444))

   * Connector/ODBC now supports batched statements. In order to enable
     cached statement support you must switch enable the batched
     statement option (`FLAG_MULTI_STATEMENTS', 67108864, or `Allow
     multiple statements' within a GUI configuration). Be aware that
     batched statements create an increased chance of SQL injection
     attacks and you must ensure that your application protects against
     this scenario.  (Bug#7445 (http://bugs.mysql.com/7445))

   * The `SQL_ATTR_ROW_BIND_OFFSET_PTR' is now supported for row bind
     offsets.  (Bug#6741 (http://bugs.mysql.com/6741))

   * The `TRACE' and `TRACEFILE' DSN options have been removed. Use the
     ODBC driver manager trace options instead.

Bugs fixed:

   * When using a table with multiple `TIMESTAMP' columns, the final
     `TIMESTAMP' column within the table definition would not be
     updateable. Note that there is still a limitation in MySQL server
     regarding multiple `TIMESTAMP' columns . (Bug#9927
     (http://bugs.mysql.com/9927)) (Bug#30081
     (http://bugs.mysql.com/30081))

   * Fixed an issue where the `myodbc3i' would update the the user ODBC
     configuration file (`~/Library/ODBC/odbcinst.ini') instead of the
     system `/Library/ODBC/odbcinst.ini'. This was caused because
     `myodbc3i' was not honouring the `s' and `u' modifiers for the
     `-d' command-line option.  (Bug#29964
     (http://bugs.mysql.com/29964))

   * Getting table metadata (through the `SQLColumns()' would fail,
     returning a bad table definition to calling applications.
     (Bug#29888 (http://bugs.mysql.com/29888))

   * `DATETIME' column types would return `FALSE' in place of
     `SQL_SUCCESS' when requesting the column type information.
     (Bug#28657 (http://bugs.mysql.com/28657))

   * The `SQL_COLUMN_TYPE', `SQL_COLUMN_DISPLAY' and
     `SQL_COLUMN_PRECISION' values would be returned incorrectly by
     `SQLColumns()', `SQLDescribeCol()' and `SQLColAttribute()' when
     accessing character columns, especially those generated through
     `concat()'. The lengths returned should now conform to the ODBC
     specification. The `FLAG_FIELD_LENGTH' option no longer has any
     affect on the results returned.  (Bug#27862
     (http://bugs.mysql.com/27862))

   * Obtaining the length of a column when using a character set for
     the connection of `utf8' would result in the length being returned
     incorrectly.  (Bug#19345 (http://bugs.mysql.com/19345))

   * The `SQLColumns()' function could return incorrect information
     about `TIMESTAMP' columns, indicating that the field was not
     nullable.  (Bug#14414 (http://bugs.mysql.com/14414))

   * The `SQLColumns()' function could return incorrect information
     about `AUTO_INCREMENT' columns, indicating that the field was not
     nullable.  (Bug#14407 (http://bugs.mysql.com/14407))

   * A binary package without an installer is available for Microsoft
     Windows x64 Edition. There are no installer packages for Microsoft
     Windows x64 Edition.

   * There is no binary package for Mac OS X on 64-bit PowerPC because
     Apple does not currently provide a 64-bit PowerPC version of iODBC.

   * `BIT(n)' columns are now treated as `SQL_BIT' data where `n = 1'
     and binary data where `n > 1'.

   * The wrong value from `SQL_DESC_LITERAL_SUFFIX' was returned for
     binary fields.

   * The `SQL_DATETIME_SUB' column in SQLColumns() was not correctly
     set for date and time types.

   * The value for `SQL_DESC_FIXED_PREC_SCALE' was not returned
     correctly for values in MySQL 5.0 and later.

   * The wrong value for `SQL_DESC_TYPE' was returned for date and time
     types.

   * `SQLConnect()' and `SQLDriverConnect()' were rewritten to
     eliminate duplicate code and ensure all options were supported
     using both connection methods.  `SQLDriverConnect()' now only
     requires the setup library to be present when the call requires it.

   * The HP-UX 11.23 IA64 binary package does not include the GUI bits
     because of problems building Qt on that platform.

   * Binary packages as disk images with installers are now available
     for Mac OS X.

   * Binary packages for Sun Solaris are now available as `PKG'
     packages.

   * The wrong value for `DECIMAL_DIGITS' in `SQLColumns()' was
     reported for `FLOAT' and `DOUBLE' fields, as well as the wrong
     value for the scale parameter to `SQLDescribeCol()', and the
     `SQL_DESC_SCALE' attribute from `SQLColAttribute()'.

   * The `SQL_DATA_TYPE' column in `SQLColumns()' results did not
     report the correct value for date and time types.


File: manual.info,  Node: myodbc-news-3-51-17,  Next: myodbc-news-3-51-16,  Prev: myodbc-news-3-51-18,  Up: myodbc-news

C.2.27 Changes in MySQL Connector/ODBC 3.51.17 (14 July 2007)
-------------------------------------------------------------

Platform specific notes:

   * The HP-UX 11.23 IA64 binary package does not include the GUI bits
     because of problems building Qt on that platform.

   * There is no binary package for Mac OS X on 64-bit PowerPC because
     Apple does not currently provide a 64-bit PowerPC version of iODBC.

   * Binary packages for Sun Solaris are now available as `PKG'
     packages.

   * Binary packages as disk images with installers are now available
     for Mac OS X.

   * A binary package without an installer is available for Microsoft
     Windows x64 Edition. There are no installer packages for Microsoft
     Windows x64 Edition.

Functionality added or changed:

   * It is now possible to specify a different character set as part of
     the DSN or connection string. This must be used instead of the
     `SET NAMES' statement. You can also configure the character set
     value from the GUI configuration.  (Bug#9498
     (http://bugs.mysql.com/9498), Bug#6667
     (http://bugs.mysql.com/6667))

   * Fixed calling convention ptr and wrong free in `myodbc3i', and
     fixed the null terminating (was only one, not two) when writing
     DSN to string.

   * Dis-allow NULL ptr for null indicator when calling SQLGetData() if
     value is null. Now returns SQL_ERROR w/state 22002.

   * The setup library has been split into its own RPM package, to
     allow installing the driver itself with no GUI dependencies.

Bugs fixed:

   * `myodbc3i' did not correctly format driver info, which could cause
     the installation to fail.  (Bug#29709
     (http://bugs.mysql.com/29709))

   * Connector/ODBC crashed with Crystal Reports due to a rproblem with
     `SQLProcedures()'.  (Bug#28316 (http://bugs.mysql.com/28316))

   * Fixed a problem where the GUI would crash when configuring or
     removing a System or User DSN.  (Bug#27315
     (http://bugs.mysql.com/27315))

   * Fixed error handling of out-of-memory and bad connections in
     catalog functions. This might raise errors in code paths that had
     ignored them in the past.  (Bug#26934
     (http://bugs.mysql.com/26934))

   * For a stored procedure that returns multiple result sets,
     Connector/ODBC returned only the first result set.  (Bug#16817
     (http://bugs.mysql.com/16817))

   * Calling `SQLGetDiagField' with `RecNumber 0, DiagIdentifier NOT 0'
     returned `SQL_ERROR', preventing access to diagnostic header
     fields.  (Bug#16224 (http://bugs.mysql.com/16224))

   * Added a new DSN option (`FLAG_ZERO_DATE_TO_MIN') to retrieve
     `XXXX-00-00' dates as the minimum allowed ODBC date
     (`XXXX-01-01'). Added another option (`FLAG_MIN_DATE_TO_ZERO') to
     mirror this but for bound parameters. `FLAG_MIN_DATE_TO_ZERO' only
     changes `0000-01-01' to `0000-00-00'.  (Bug#13766
     (http://bugs.mysql.com/13766))

   * If there was more than one unique key on a table, the correct
     fields were not used in handling `SQLSetPos()'.  (Bug#10563
     (http://bugs.mysql.com/10563))

   * When inserting a large `BLOB' field, Connector/ODBC would crash
     due to a memory allocation error.  (Bug#10562
     (http://bugs.mysql.com/10562))

   * The driver was using `mysql_odbc_escape_string()', which does not
     handle the `NO_BACKSLASH_ESCAPES' SQL mode. Now it uses *Note
     `mysql_real_escape_string()': mysql-real-escape-string, which does.
     (Bug#9498 (http://bugs.mysql.com/9498))

   * `SQLColumns()' did not handle many of its parameters correctly,
     which could lead to incorrect results. The table name argument was
     not handled as a pattern value, and most arguments were not
     escaped correctly when they contained non-alphanumeric characters.
     (Bug#8860 (http://bugs.mysql.com/8860))

   * There are no binary packages for Microsoft Windows x64 Edition.

   * There is no binary package for Mac OS X on 64-bit PowerPC because
     Apple does not currently provide a 64-bit PowerPC version of iODBC.

   * Correctly return error if `SQLBindCol' is called with an invalid
     column.

   * Fixed possible crash if `SQLBindCol()' was not called before
     `SQLSetPos()'.

   * The Mac OS X binary packages are only provided as tarballs, there
     is no installer.

   * The binary packages for Sun Solaris are only provided as tarballs,
     not the PKG format.

   * The HP-UX 11.23 IA64 binary package does not include the GUI bits
     because of problems building Qt on that platform.


File: manual.info,  Node: myodbc-news-3-51-16,  Next: myodbc-news-3-51-15,  Prev: myodbc-news-3-51-17,  Up: myodbc-news

C.2.28 Changes in MySQL Connector/ODBC 3.51.16 (14 June 2007)
-------------------------------------------------------------

Functionality added or changed:

   * Connector/ODBC now supports using SSL for communication. This is
     not yet exposed in the setup GUI, but must be enabled through
     configuration files or the DSN.  (Bug#12918
     (http://bugs.mysql.com/12918))

Bugs fixed:

   * Calls to SQLNativeSql() could cause stack corruption due to an
     incorrect pointer cast.  (Bug#28758 (http://bugs.mysql.com/28758))

   * Using curors on results sets with multi-column keys could select
     the wrong value.  (Bug#28255 (http://bugs.mysql.com/28255))

   * `SQLForeignKeys' does not escape `_' and `%' in the table name
     arguments.  (Bug#27723 (http://bugs.mysql.com/27723))

   * When using stored procedures, making a `SELECT' or second stored
     procedure call after an initial stored procedure call, the second
     statement will fail.  (Bug#27544 (http://bugs.mysql.com/27544))

   * SQLTables() did not distinguish tables from views.  (Bug#23031
     (http://bugs.mysql.com/23031))

   * Data in `TEXT' columns would fail to be read correctly.
     (Bug#16917 (http://bugs.mysql.com/16917))

   * Specifying strings as parameters using the `adBSTR' or `adVarWChar'
     types, (`SQL_WVARCHAR' and `SQL_WLONGVARCHAR') would be incorrectly
     quoted.  (Bug#16235 (http://bugs.mysql.com/16235))

   * SQL_WVARCHAR and SQL_WLONGVARCHAR parameters were not properly
     quoted and escaped.  (Bug#16235 (http://bugs.mysql.com/16235))

   * Using `BETWEEN' with date values, the wrong results could be
     returned.  (Bug#15773 (http://bugs.mysql.com/15773))

   * When using the `Don't Cache Results' (option value `1048576') with
     Microsoft Access, the connection will fail using DAO/VisualBasic.
     (Bug#4657 (http://bugs.mysql.com/4657))

   * Return values from `SQLTables()' may be truncated. (Bugs #22797)


File: manual.info,  Node: myodbc-news-3-51-15,  Next: myodbc-news-3-51-14,  Prev: myodbc-news-3-51-16,  Up: myodbc-news

C.2.29 Changes in MySQL Connector/ODBC 3.51.15 (07 May 2007)
------------------------------------------------------------

Bugs fixed:

   * Connector/ODBC would incorrectly claim to support
     `SQLProcedureColumns' (by returning true when queried about
     `SQLPROCEDURECOLUMNS' with `SQLGetFunctions'), but this
     functionality is not supported.  (Bug#27591
     (http://bugs.mysql.com/27591))

   * An incorrect transaction isolation level may not be returned when
     accessing the connection attributes.  (Bug#27589
     (http://bugs.mysql.com/27589))

   * Adding a new DSN with the `myodbc3i' utility under AIX would fail.
     (Bug#27220 (http://bugs.mysql.com/27220))

   * When inserting data using bulk statements (through
     `SQLBulkOperations'), the indicators for all rows within the
     insert would not updated correctly.  (Bug#24306
     (http://bugs.mysql.com/24306))

   * Using `SQLProcedures' does not return the database name within the
     returned resultset.  (Bug#23033 (http://bugs.mysql.com/23033))

   * The `SQLTransact()' function did not support an empty connection
     handle.  (Bug#21588 (http://bugs.mysql.com/21588))

   * Using `SQLDriverConnect' instead of `SQLConnect' could cause later
     operations to fail.  (Bug#7912 (http://bugs.mysql.com/7912))

   * When using blobs and parameter replacement in a statement with
     `WHERE CURSOR OF', the SQL is truncated.  (Bug#5853
     (http://bugs.mysql.com/5853))

   * Connector/ODBC would return too many foreign key results when
     accessing tables with similar names.  (Bug#4518
     (http://bugs.mysql.com/4518))

   *

File: manual.info,  Node: myodbc-news-3-51-14,  Next: myodbc-news-3-51-13,  Prev: myodbc-news-3-51-15,  Up: myodbc-news

C.2.30 Changes in MySQL Connector/ODBC 3.51.14 (08 March 2007)
--------------------------------------------------------------

Functionality added or changed:

   * Use of `SQL_ATTR_CONNECTION_TIMEOUT' on the server has now been
     disabled. If you attempt to set this attribute on your connection
     the `SQL_SUCCESS_WITH_INFO' will be returned, with an error
     number/string of `HYC00: Optional feature not supported'.
     (Bug#19823 (http://bugs.mysql.com/19823))

   * Added auto is null option to Connector/ODBC option parameters.
     (Bug#10910 (http://bugs.mysql.com/10910))

   * Added auto-reconnect option to Connector/ODBC option parameters.

   * Added support for the `HENV' handlers in `SQLEndTran()'.

Bugs fixed:

   * On 64-bit systems, some types would be incorrectly returned.
     (Bug#26024 (http://bugs.mysql.com/26024))

   * When retrieving `TIME' columns, C/ODBC would incorrectly interpret
     the type of the string and could interpret it as a `DATE' type
     instead.  (Bug#25846 (http://bugs.mysql.com/25846))

   * Connector/ODBC may insert the wrong parameter values when using
     prepared statements under 64-bit Linux.  (Bug#22446
     (http://bugs.mysql.com/22446))

   * Using Connector/ODBC, with `SQLBindCol' and binding the length to
     the return value from `SQL_LEN_DATA_AT_EXEC' fails with a memory
     allocation error.  (Bug#20547 (http://bugs.mysql.com/20547))

   * Using `DataAdapter', Connector/ODBC may continually consume memory
     when reading the same records within a loop (Windows Server 2003
     SP1/SP2 only).  (Bug#20459 (http://bugs.mysql.com/20459))

   * When retrieving data from columns that have been compressed using
     `COMPRESS()', the retrieved data would be truncated to 8KB.
     (Bug#20208 (http://bugs.mysql.com/20208))

   * The ODBC driver name and version number were incorrectly reported
     by the driver.  (Bug#19740 (http://bugs.mysql.com/19740))

   * A string format exception would be raised when using iODBC,
     Connector/ODBC and the embedded MySQL server.  (Bug#16535
     (http://bugs.mysql.com/16535))

   * The `SQLDriverConnect()' ODBC method did not work with recent
     Connector/ODBC releases.  (Bug#12393 (http://bugs.mysql.com/12393))


File: manual.info,  Node: myodbc-news-3-51-13,  Next: myodbc-news-3-51-12,  Prev: myodbc-news-3-51-14,  Up: myodbc-news

C.2.31 Changes in MySQL Connector/ODBC 3.51.13 (Never released)
---------------------------------------------------------------

Connector/ODBC 3.51.13 was an internal implementation and testing
release.


File: manual.info,  Node: myodbc-news-3-51-12,  Next: myodbc-news-3-51-11,  Prev: myodbc-news-3-51-13,  Up: myodbc-news

C.2.32 Changes in MySQL Connector/ODBC 3.51.12 (11 Febrauary 2005)
------------------------------------------------------------------

Functionality added or changed:

   * N/A

Bugs fixed:

   * Using stored procedures with ADO, where the `CommantType' has been
     set correctly to `adCmdStoredProc', calls to stored procedures
     would fail.  (Bug#15635 (http://bugs.mysql.com/15635))

   * File DSNs could not be saved.  (Bug#12019
     (http://bugs.mysql.com/12019))

   * `SQLColumns()' returned no information for tables that had a
     column named using a reserved word.  (Bug#9539
     (http://bugs.mysql.com/9539))


File: manual.info,  Node: myodbc-news-3-51-11,  Prev: myodbc-news-3-51-12,  Up: myodbc-news

C.2.33 Changes in MySQL Connector/ODBC 3.51.11 (28 January 2005)
----------------------------------------------------------------

Bugs fixed:

   * `mysql_list_dbcolumns()' and `insert_fields()' were retrieving all
     rows from a table. Fixed the queries generated by these functions
     to return no rows.  (Bug#8198 (http://bugs.mysql.com/8198))

   * `SQLGetTypoInfo()' returned `tinyblob' for `SQL_VARBINARY' and
     nothing for `SQL_BINARY'. Fixed to return `varbinary' for
     `SQL_VARBINARY', `binary' for `SQL_BINARY', and `longblob' for
     `SQL_LONGVARBINARY'.  (Bug#8138 (http://bugs.mysql.com/8138))


File: manual.info,  Node: connector-net-news,  Next: vstudio-plugin-news,  Prev: myodbc-news,  Up: news

C.3 MySQL Connector/NET Change History
======================================

* Menu:

* connector-net-news-5-3-0::     Changes in MySQL Connector/NET 5.3.0 (Not yet released)
* connector-net-news-5-2-3::     Changes in MySQL Connector/NET 5.2.3 (Not yet released)
* connector-net-news-5-2-2::     Changes in MySQL Connector/NET 5.2.2 (12 May 2008)
* connector-net-news-5-2-1::     Changes in MySQL Connector/NET 5.2.1 (27 February 2008)
* connector-net-news-5-2-0::     Changes in MySQL Connector/NET 5.2.0 (11 February 2008)
* connector-net-news-5-1-7::     Changes in MySQL Connector/NET 5.1.7 (Not yet released)
* connector-net-news-5-1-6::     Changes in MySQL Connector/NET 5.1.6 (12 May 2008)
* connector-net-news-5-1-5::     Changes in MySQL Connector/NET 5.1.5 (Not yet released)
* connector-net-news-5-1-4::     Changes in MySQL Connector/NET 5.1.4 (20 November 2007)
* connector-net-news-5-1-3::     Changes in MySQL Connector/NET 5.1.3 (21 September 2007)
* connector-net-news-5-1-2::     Changes in MySQL Connector/NET 5.1.2 (18 June 2007)
* connector-net-news-5-1-1::     Changes in MySQL Connector/NET 5.1.1 (23 May 2007)
* connector-net-news-5-1-0::     Changes in MySQL Connector/NET 5.1.0 (01 May 2007)
* connector-net-news-5-0-10::    Changes in MySQL Connector/NET 5.0.10 (Not yet released)
* connector-net-news-5-0-9::     Changes in MySQL Connector/NET 5.0.9 (Not yet released)
* connector-net-news-5-0-8::     Changes in MySQL Connector/NET 5.0.8 (21 August 2007)
* connector-net-news-5-0-7::     Changes in MySQL Connector/NET 5.0.7 (18 May 2007)
* connector-net-news-5-0-6::     Changes in MySQL Connector/NET 5.0.6 (22 March 2007)
* connector-net-news-5-0-5::     Changes in MySQL Connector/NET 5.0.5 (07 March 2007)
* connector-net-news-5-0-4::     Changes in MySQL Connector/NET 5.0.4 (Not released)
* connector-net-news-5-0-3::     Changes in MySQL Connector/NET 5.0.3 (05 January 2007)
* connector-net-news-5-0-2::     Changes in MySQL Connector/NET 5.0.2 (06 November 2006)
* connector-net-news-5-0-1::     Changes in MySQL Connector/NET 5.0.1 (01 October 2006)
* connector-net-news-5-0-0::     Changes in MySQL Connector/NET 5.0.0 (08 August 2006)
* connector-net-news-1-0-11::    Changes in MySQL Connector/NET 1.0.11 (Not yet released)
* connector-net-news-1-0-10::    Changes in MySQL Connector/NET 1.0.10 (24 August 2007)
* connector-net-news-1-0-9::     Changes in MySQL Connector/NET 1.0.9 (02 February 2007)
* connector-net-news-1-0-8::     Changes in MySQL Connector/NET 1.0.8 (20 October 2006)
* connector-net-news-1-0-7::     Changes in MySQL Connector/NET 1.0.7 (21 November 2005)
* connector-net-news-1-0-6::     Changes in MySQL Connector/NET 1.0.6 (03 October 2005)
* connector-net-news-1-0-5::     Changes in MySQL Connector/NET 1.0.5 (29 August 2005)
* connector-net-news-1-0-4::     Changes in MySQL Connector/NET 1.0.4 (20 January 2005)
* connector-net-news-1-0-3::     Changes in MySQL Connector/NET 1.0.3 (12 October 2004)
* connector-net-news-1-0-2::     Changes in MySQL Connector/NET 1.0.2 (15 November 2004)
* connector-net-news-1-0-1::     Changes in MySQL Connector/NET 1.0.1 (27 October 2004)
* connector-net-news-1-0-0::     Changes in MySQL Connector/NET 1.0.0 (01 September 2004)
* connector-net-0-9-0::          Changes in MySQL Connector/NET Version 0.9.0 (30 August 2004)
* connector-net-news-0-76::      Changes in MySQL Connector/NET Version 0.76
* connector-net-news-0-75::      Changes in MySQL Connector/NET Version 0.75
* connector-net-0-74::           Changes in MySQL Connector/NET Version 0.74
* connector-net-news-0-71::      Changes in MySQL Connector/NET Version 0.71
* connector-net-news-0-70::      Changes in MySQL Connector/NET Version 0.70
* connector-net-news-0-68::      Changes in MySQL Connector/NET Version 0.68
* connector-net-news-0-65::      Changes in MySQL Connector/NET Version 0.65
* connector-net-news-0-60::      Changes in MySQL Connector/NET Version 0.60
* connector-net-news-0-50::      Changes in MySQL Connector/NET Version 0.50


File: manual.info,  Node: connector-net-news-5-3-0,  Next: connector-net-news-5-2-3,  Prev: connector-net-news,  Up: connector-net-news

C.3.1 Changes in MySQL Connector/NET 5.3.0 (Not yet released)
-------------------------------------------------------------

Bugs fixed:

   * Possible overflow in MySqlPacket.ReadLong().  (Bug#36997
     (http://bugs.mysql.com/36997))

   * The TokenizeSql method was adding query overhead and causing high
     CPU utilization for larger queries.  (Bug#36836
     (http://bugs.mysql.com/36836))


File: manual.info,  Node: connector-net-news-5-2-3,  Next: connector-net-news-5-2-2,  Prev: connector-net-news-5-3-0,  Up: connector-net-news

C.3.2 Changes in MySQL Connector/NET 5.2.3 (Not yet released)
-------------------------------------------------------------

Functionality added or changed:

   * Error string was returned after a 28000 second `wait_timeout'.
     This has been changed to generate a `ConnectionState.Closed' event.
     (Bug#38119 (http://bugs.mysql.com/38119))

   * Changed how the procedure schema collection is retrieved. If the
     connection string contains ``use procedure bodies=true'' then a
     `SELECT' is performed on the `mysql.proc' table directly, as this
     is up to 50 times faster than the current Information Schema
     implementation. If the connection string contains ``use procedure
     bodies=false'', then the Information Schema collection is queried.
     (Bug#36694 (http://bugs.mysql.com/36694))

   * Changed how the procedure schema collection is retrieved. If `use
     procedure bodies=true' then the `mysql.proc' table is selected
     directly as this is up to 50 times faster than the current
     `information_schema' implementation. If `use procedure
     bodies=false', then the `information_schema' collection is queried.
     (Bug#36694 (http://bugs.mysql.com/36694))

   * String escaping functionality has been moved from the MySqlString
     class to the MySqlHelper class, where it can be accessed by the
     EscapeString method.  (Bug#36205 (http://bugs.mysql.com/36205))

Bugs fixed:

   * There was a short circuit evaluation error in the
     MySqlCommand.CheckState() method. When the statement `connection
     == null' was true a NullReferenceException was thrown and not the
     expected InvalidOperationException.  (Bug#38276
     (http://bugs.mysql.com/38276))

   * The provider did not silently create the user if the user did not
     exist.  (Bug#38243 (http://bugs.mysql.com/38243))

   * Executing a command that resulted in a fatal exception did not
     close the connection.  (Bug#37991 (http://bugs.mysql.com/37991))

   * When a prepared insert query is run that contains an `UNSIGNED
     TINYINT' in the parameter list, the complete query and data that
     should be inserted is corrupted and no error is thrown.
     (Bug#37968 (http://bugs.mysql.com/37968))

   * In a .NET application MySQL Connector/NET modifies the connection
     string so that it contains several occurrences of the same option
     with different values. This is illustrated by the example that
     follows.

     The original connection string:

            host=localhost;database=test;uid=*****;pwd=*****;
            connect timeout=25; auto enlist=false;pooling=false;

     The connection string after after closing MySqlDataReader:

            host=localhost;database=test;uid=*****;pwd=*****;
            connect timeout=25;auto enlist=false;pooling=false;
            Allow User Variables=True;Allow User Variables=False;
            Allow User Variables=True;Allow User Variables=False;

     (Bug#37955 (http://bugs.mysql.com/37955))

   * Unnecessary network traffic was generated for the normal case
     where the web provider schema was up to date.  (Bug#37469
     (http://bugs.mysql.com/37469))

   * MySqlReader.GetOrdinal() performance enhancements break existing
     functionality.  (Bug#37239 (http://bugs.mysql.com/37239))

   * The `autogenerateschema' option produced tables with incorrect
     collations.  (Bug#36444 (http://bugs.mysql.com/36444))

   * GetSchema did not work correctly when querying for a collection,
     if using a non-English locale.  (Bug#35459
     (http://bugs.mysql.com/35459))

   * When reading back a stored double or single value using the .NET
     provider, the value had less precision than the one stored.
     (Bug#33322 (http://bugs.mysql.com/33322))

   * Using the MySQL Visual Studio plugin and a MySQL 4.1 server,
     certain field types (`ENUM') would not be identified correctly.
     Also, when looking for tables, the plugin would list all tables
     matching a wildcard pattern of the database name supplied in the
     connection string, instead of only tables within the specified
     database.  (Bug#30603 (http://bugs.mysql.com/30603))


File: manual.info,  Node: connector-net-news-5-2-2,  Next: connector-net-news-5-2-1,  Prev: connector-net-news-5-2-3,  Up: connector-net-news

C.3.3 Changes in MySQL Connector/NET 5.2.2 (12 May 2008)
--------------------------------------------------------

Bugs fixed:

   * Product documentation incorrectly stated '?' is the preferred
     parameter marker.  (Bug#37349 (http://bugs.mysql.com/37349))

   * An incorrect value for a bit field would returned in a multi-row
     query if a preceding value for the field returned `NULL'.
     (Bug#36313 (http://bugs.mysql.com/36313))

   * Tables with `GEOMETRY' field types would return an unknown
     datatype exception.  (Bug#36081 (http://bugs.mysql.com/36081))

   * When using the `MySQLProfileProvider', setting profile details and
     then reading back saved data would result in the default values
     being returned instead of the updated values.  (Bug#36000
     (http://bugs.mysql.com/36000))

   * When creating a connection, setting the `ConnectionString'
     property of `MySqlConnection' to `NULL' would throw an exception.
     (Bug#35619 (http://bugs.mysql.com/35619))

   * The DbCommandBuilder.QuoteIdentifer method was not implemented.
     (Bug#35492 (http://bugs.mysql.com/35492))

   * When using encrypted passwords, the `GetPassword()' function would
     return the wrong string.  (Bug#35336 (http://bugs.mysql.com/35336))

   * An error would be raised when calling `GetPassword()' with a `NULL'
     value.  (Bug#35332 (http://bugs.mysql.com/35332))

   * When retreiving data where a field has been identified as
     containing a GUID value, the incorrect value would be returned
     when a previous row contained a `NULL' value for that field.
     (Bug#35041 (http://bugs.mysql.com/35041))

   * Using the `TableAdapter Wizard' would fail when generating
     commands that used stored procedures due to the change in
     supported parameter characters.  (Bug#34941
     (http://bugs.mysql.com/34941))

   * When creating a new stored procedured, the new parameter code
     which allows the use of the `@' symbol would interfere with the
     specification of a `DEFINER'.  (Bug#34940
     (http://bugs.mysql.com/34940))

   * When using `SqlDataSource' to open a connection, the connection
     would not automatically be closed when access had completed.
     (Bug#34460 (http://bugs.mysql.com/34460))

   * There was a high level of contention in the connection pooling
     code that could lead to delays when opening connections and
     submitting queries. The connection pooling code has been modified
     to try and limit the effects of the contention issue.  (Bug#34001
     (http://bugs.mysql.com/34001))

   * Using the `TableAdaptor' wizard in combination with a suitable
     `SELECT' statement, only the associated `INSERT' statement would
     also be created, rather than the required `DELETE' and `UPDATE'
     statements.  (Bug#31338 (http://bugs.mysql.com/31338))

   * Fixed problem in datagrid code related to creating a new table.
     This problem may have been introduced with .NET 2.0 SP1.

   * Fixed profile provider that would throw an exception if you were
     updating a profile that already existed.


File: manual.info,  Node: connector-net-news-5-2-1,  Next: connector-net-news-5-2-0,  Prev: connector-net-news-5-2-2,  Up: connector-net-news

C.3.4 Changes in MySQL Connector/NET 5.2.1 (27 February 2008)
-------------------------------------------------------------

Bugs fixed:

   * When using the provider to generate or update users and passwords,
     the password checking algorithm would not validate the password
     strength or requirements correctly.  (Bug#34792
     (http://bugs.mysql.com/34792))

   * When executing statements that used stored procedures and
     functions, the new parameter code could fail to identify the
     correct parameter format.  (Bug#34699
     (http://bugs.mysql.com/34699))

   * The installer would fail to the DDEX provider binary if the Visual
     Studio 2005 component was not selected. The result would lead to
     Connector/NET not loading properly when using the interface to a
     MySQL server within Visual Studio.  (Bug#34674
     (http://bugs.mysql.com/34674))

   * A number issues were identified in the case, connection and scema
     areas of the code for `MembershipProvider', `RoleProvider',
     `ProfileProvider'.  (Bug#34495 (http://bugs.mysql.com/34495))

   * When using web providers, the Connector/NET would check the schema
     and cache the application id, even when the connection string had
     been set. The effect would be to break the memvership provider
     list.  (Bug#34451 (http://bugs.mysql.com/34451))

   * Attempting to use an isolation level other than the default with a
     transaction scope would use the default isolation level.
     (Bug#34448 (http://bugs.mysql.com/34448))

   * When altering a stored procedure within Visual Studio, the
     parameters to the procedure could be lost.  (Bug#34359
     (http://bugs.mysql.com/34359))

   * A race condition could occur within the procedure cache resulting
     the cache contents overflowing beyond the configured cache size.
     (Bug#34338 (http://bugs.mysql.com/34338))

   * Fixed problem with Visual Studio 2008 integration that caused
     pop-up menus on server explorer nodes to not function

   * The provider code has been updated to fix a number of outstanding
     issues.


File: manual.info,  Node: connector-net-news-5-2-0,  Next: connector-net-news-5-1-7,  Prev: connector-net-news-5-2-1,  Up: connector-net-news

C.3.5 Changes in MySQL Connector/NET 5.2.0 (11 February 2008)
-------------------------------------------------------------

Functionality added or changed:

   * Performing `GetValue()' on a field `TINYINT(1)' returned a
     `BOOLEAN'. While not a bug, this caused problems in software that
     expected an `INT' to be returned. A new connection string option
     `Treat Tiny As Boolean' has been added with a default value of
     `true'. If set to `false' the provider will treat `TINYINT(1)' as
     `INT'.  (Bug#34052 (http://bugs.mysql.com/34052))

   * Added support for `DbDataAdapter' `UpdateBatchSize'. Batching is
     fully supported including collapsing inserts down into the
     multi-value form if possible.

   * DDEX provider now works under Visual Studio 2008 beta 2.

   * Added ClearPool and ClearAllPools features.

Bugs fixed:

   * Some speed improvements have been implemented in the `TokenizeSql'
     process used to identify elements of SQL statements.  (Bug#34220
     (http://bugs.mysql.com/34220))

   * When accessing tables from different databases within the same
     `TransactionScope', the same user/password combination would be
     used for each database connection.  Connector/NET does not handle
     multiple connections within the same transaction scope. An error
     is now returned if you attempt this process, instead of using the
     incorrect authorization information.  (Bug#34204
     (http://bugs.mysql.com/34204))

   * The status of connections reported through the state change
     handler was not being updated correctly.  (Bug#34082
     (http://bugs.mysql.com/34082))

   * Incorporated some connection string cache optimizations sent to us
     by Maxim Mass.  (Bug#34000 (http://bugs.mysql.com/34000))

   * In an open connection where the server had disconnected
     unexpectedly, the status information of the connection would not
     be updated properly.  (Bug#33909 (http://bugs.mysql.com/33909))

   * Data cached from the connection string could return invalid
     information because the internal routines were not using
     case-sensitive semantics. This lead to updated connection string
     options not being recognized if they were of a different case than
     the existing cached values.  (Bug#31433
     (http://bugs.mysql.com/31433))

   * Column name metadata was not using the character set as deifned
     within the connection string being used.  (Bug#31185
     (http://bugs.mysql.com/31185))

   * Memory usage could increase and decrease significantly when
     updating or inserting a large number of rows.  (Bug#31090
     (http://bugs.mysql.com/31090))

   * Commands executed from within the state change handeler would fail
     with a `NULL' exception.  (Bug#30964 (http://bugs.mysql.com/30964))

   * When running a stored procedure multiple times on the same
     connection, the memory usage could increase indefinitely.
     (Bug#30116 (http://bugs.mysql.com/30116))

   * Using compression in the MySQL connection with Connector/NET would
     be slower than using native (uncompressed) communication.
     (Bug#27865 (http://bugs.mysql.com/27865))

   * The `MySqlDbType.Datetime' has been replaced with
     `MySqlDbType.DateTime'. The old format has been obsoleted.
     (Bug#26344 (http://bugs.mysql.com/26344))


File: manual.info,  Node: connector-net-news-5-1-7,  Next: connector-net-news-5-1-6,  Prev: connector-net-news-5-2-0,  Up: connector-net-news

C.3.6 Changes in MySQL Connector/NET 5.1.7 (Not yet released)
-------------------------------------------------------------

Bugs fixed:

   * There was a short circuit evaluation error in the
     MySqlCommand.CheckState() method. When the statement `connection
     == null' was true a NullReferenceException was thrown and not the
     expected InvalidOperationException.  (Bug#38276
     (http://bugs.mysql.com/38276))

   * Executing a command that resulted in a fatal exception did not
     close the connection.  (Bug#37991 (http://bugs.mysql.com/37991))

   * In a .NET application MySQL Connector/NET modifies the connection
     string so that it contains several occurrences of the same option
     with different values. This is illustrated by the example that
     follows.

     The original connection string:

            host=localhost;database=test;uid=*****;pwd=*****;
            connect timeout=25; auto enlist=false;pooling=false;

     The connection string after after closing MySqlDataReader:

            host=localhost;database=test;uid=*****;pwd=*****;
            connect timeout=25;auto enlist=false;pooling=false;
            Allow User Variables=True;Allow User Variables=False;
            Allow User Variables=True;Allow User Variables=False;

     (Bug#37955 (http://bugs.mysql.com/37955))

   * As MySqlDbType.DateTime is not available in `VB.Net' the warning
     `The datetime enum value is obsolete' was always shown during
     compilation.  (Bug#37406 (http://bugs.mysql.com/37406))

   * An unknown `MySqlErrorCode' was encountered when opening a
     connection with an incorrect password.  (Bug#37398
     (http://bugs.mysql.com/37398))

   * Documentation incorrectly stated that `the DataColumn class in
     .NET 1.0 and 1.1 does not allow columns with type of UInt16,
     UInt32, or UInt64 to be autoincrement columns'.  (Bug#37350
     (http://bugs.mysql.com/37350))

   * SemaphoreFullException is generated when application is closed.
     (Bug#36688 (http://bugs.mysql.com/36688))

   * GetSchema did not work correctly when querying for a collection,
     if using a non-English locale.  (Bug#35459
     (http://bugs.mysql.com/35459))

   * When reading back a stored double or single value using the .NET
     provider, the value had less precision than the one stored.
     (Bug#33322 (http://bugs.mysql.com/33322))

   * Using the MySQL Visual Studio plugin and a MySQL 4.1 server,
     certain field types (`ENUM') would not be identified correctly.
     Also, when looking for tables, the plugin would list all tables
     matching a wildcard pattern of the database name supplied in the
     connection string, instead of only tables within the specified
     database.  (Bug#30603 (http://bugs.mysql.com/30603))


File: manual.info,  Node: connector-net-news-5-1-6,  Next: connector-net-news-5-1-5,  Prev: connector-net-news-5-1-7,  Up: connector-net-news

C.3.7 Changes in MySQL Connector/NET 5.1.6 (12 May 2008)
--------------------------------------------------------

Bugs fixed:

   * When creating a connection pool, specifying an invalid IP address
     will cause the entire application to crash, instead of providing
     an exception.  (Bug#36432 (http://bugs.mysql.com/36432))

   * An incorrect value for a bit field would returned in a multi-row
     query if a preceding value for the field returned `NULL'.
     (Bug#36313 (http://bugs.mysql.com/36313))

   * The `MembershipProvider' will raise an exception when the
     connection string is configured with `enablePasswordRetrival =
     true' and `RequireQuestionAndAnswer = false'.  (Bug#36159
     (http://bugs.mysql.com/36159))

   * When calling `GetNumberOfUsersOnline' an exception is raised on
     the submitted query due to a missing parameter.  (Bug#36157
     (http://bugs.mysql.com/36157))

   * Tables with `GEOMETRY' field types would return an unknown
     datatype exception.  (Bug#36081 (http://bugs.mysql.com/36081))

   * When creating a connection, setting the `ConnectionString'
     property of `MySqlConnection' to `NULL' would throw an exception.
     (Bug#35619 (http://bugs.mysql.com/35619))

   * The DbCommandBuilder.QuoteIdentifer method was not implemented.
     (Bug#35492 (http://bugs.mysql.com/35492))

   * When using `SqlDataSource' to open a connection, the connection
     would not automatically be closed when access had completed.
     (Bug#34460 (http://bugs.mysql.com/34460))

   * Attempting to use an isolation level other than the default with a
     transaction scope would use the default isolation level.
     (Bug#34448 (http://bugs.mysql.com/34448))

   * When altering a stored procedure within Visual Studio, the
     parameters to the procedure could be lost.  (Bug#34359
     (http://bugs.mysql.com/34359))

   * A race condition could occur within the procedure cache resulting
     the cache contents overflowing beyond the configured cache size.
     (Bug#34338 (http://bugs.mysql.com/34338))

   * Using the `TableAdaptor' wizard in combination with a suitable
     `SELECT' statement, only the associated `INSERT' statement would
     also be created, rather than the required `DELETE' and `UPDATE'
     statements.  (Bug#31338 (http://bugs.mysql.com/31338))


File: manual.info,  Node: connector-net-news-5-1-5,  Next: connector-net-news-5-1-4,  Prev: connector-net-news-5-1-6,  Up: connector-net-news

C.3.8 Changes in MySQL Connector/NET 5.1.5 (Not yet released)
-------------------------------------------------------------

Functionality added or changed:

   * Performing `GetValue()' on a field `TINYINT(1)' returned a
     `BOOLEAN'. While not a bug, this caused problems in software that
     expected an `INT' to be returned. A new connection string option
     `Treat Tiny As Boolean' has been added with a default value of
     `true'. If set to `false' the provider will treat `TINYINT(1)' as
     `INT'.  (Bug#34052 (http://bugs.mysql.com/34052))

Bugs fixed:

   * Some speed improvements have been implemented in the `TokenizeSql'
     process used to identify elements of SQL statements.  (Bug#34220
     (http://bugs.mysql.com/34220))

   * When accessing tables from different databases within the same
     `TransactionScope', the same user/password combination would be
     used for each database connection.  Connector/NET does not handle
     multiple connections within the same transaction scope. An error
     is now returned if you attempt this process, instead of using the
     incorrect authorization information.  (Bug#34204
     (http://bugs.mysql.com/34204))

   * The status of connections reported through the state change
     handler was not being updated correctly.  (Bug#34082
     (http://bugs.mysql.com/34082))

   * Incorporated some connection string cache optimizations sent to us
     by Maxim Mass.  (Bug#34000 (http://bugs.mysql.com/34000))

   * In an open connection where the server had disconnected
     unexpectedly, the status information of the connection would not
     be updated properly.  (Bug#33909 (http://bugs.mysql.com/33909))

   * Connector/NET would fail to compile properly with `nant'.
     (Bug#33508 (http://bugs.mysql.com/33508))

   * Problem with membership provider would mean that `FindUserByEmail'
     would fail with a `MySqlException' because it was trying to add a
     second parameter with the same name as the first.  (Bug#33347
     (http://bugs.mysql.com/33347))

   * Using compression in the MySQL connection with Connector/NET would
     be slower than using native (uncompressed) communication.
     (Bug#27865 (http://bugs.mysql.com/27865))


File: manual.info,  Node: connector-net-news-5-1-4,  Next: connector-net-news-5-1-3,  Prev: connector-net-news-5-1-5,  Up: connector-net-news

C.3.9 Changes in MySQL Connector/NET 5.1.4 (20 November 2007)
-------------------------------------------------------------

Bugs fixed:

   * Setting the size of a string parameter after the value could cause
     an exception.  (Bug#32094 (http://bugs.mysql.com/32094))

   * Creation of parameter objects with non-input direction using a
     constructor would fail. This was cause by some old legacy code
     preventing their use.  (Bug#32093 (http://bugs.mysql.com/32093))

   * A date string could be returned incorrectly by
     `MySqlDataTime.ToString()' when the date returned by MySQL was
     `0000-00-00 00:00:00'.  (Bug#32010 (http://bugs.mysql.com/32010))

   * A syntax error in a set of batch statements could leave the data
     adapter in a state that appears hung.  (Bug#31930
     (http://bugs.mysql.com/31930))

   * Installing over a failed uninstall of a previous version could
     result in multiple clients being registered in the
     `machine.config'. This would prevent certain aspects of the MySQL
     connection within Visual Studio to work properly.  (Bug#31731
     (http://bugs.mysql.com/31731))

   * Connector/NET would incorrectly report success when enlisting in a
     distributed transaction, although distributed transactions are not
     supported.  (Bug#31703 (http://bugs.mysql.com/31703))

   * Data cached from the connection string could return invalid
     information because the internal routines were not using
     case-sensitive semantics. This lead to updated connection string
     options not being recognized if they were of a different case than
     the existing cached values.  (Bug#31433
     (http://bugs.mysql.com/31433))

   * Trying to use a connection that was not open could return an
     ambiguous and misleading error message.  (Bug#31262
     (http://bugs.mysql.com/31262))

   * Column name metadata was not using the character set as deifned
     within the connection string being used.  (Bug#31185
     (http://bugs.mysql.com/31185))

   * Memory usage could increase and decrease significantly when
     updating or inserting a large number of rows.  (Bug#31090
     (http://bugs.mysql.com/31090))

   * Commands executed from within the state change handeler would fail
     with a `NULL' exception.  (Bug#30964 (http://bugs.mysql.com/30964))

   * Extracting data through XML functions within a query returns the
     data as `System.Byte[]'. This was due to Connector/NET incorrectly
     identifying `BLOB' fields as binary, rather than text.  (Bug#30233
     (http://bugs.mysql.com/30233))

   * When running a stored procedure multiple times on the same
     connection, the memory usage could increase indefinitely.
     (Bug#30116 (http://bugs.mysql.com/30116))

   * Column types with only 1-bit (such as `BOOLEAN' and `TINYINT(1)'
     were not returned as boolean fields.  (Bug#27959
     (http://bugs.mysql.com/27959))

   * When accessing certain statements, the command would timeout
     before the command completed. Because this cannot always be
     controlled through the individual command timeout options, a
     `default command timeout' has been added to the connection string
     options.  (Bug#27958 (http://bugs.mysql.com/27958))

   * The server error code was not updated in the `Data[]' hash, which
     prevented `DbProviderFactory' users from accessing the server
     error code.  (Bug#27436 (http://bugs.mysql.com/27436))

   * The `MySqlDbType.Datetime' has been replaced with
     `MySqlDbType.DateTime'. The old format has been obsoleted.
     (Bug#26344 (http://bugs.mysql.com/26344))

   * Changing the connection string of a connection to one that changes
     the parameter marker after the connection had been assigned to a
     command but before the connection is opened could cause parameters
     to not be found.  (Bug#13991 (http://bugs.mysql.com/13991))


File: manual.info,  Node: connector-net-news-5-1-3,  Next: connector-net-news-5-1-2,  Prev: connector-net-news-5-1-4,  Up: connector-net-news

C.3.10 Changes in MySQL Connector/NET 5.1.3 (21 September 2007)
---------------------------------------------------------------

This is a new Beta development release, fixing recently discovered bugs.

Bugs fixed:

   * An incorrect `ConstraintException' could be raised on an `INSERT'
     when adding rows to a table with a multiple-column unique key
     index.  (Bug#30204 (http://bugs.mysql.com/30204))

   * A `DATE' field would be updated with a date/time value, causing a
     `MySqlDataAdapter.Update()' exception.  (Bug#30077
     (http://bugs.mysql.com/30077))

   * The Saudi Hijri calendar was not supported.  (Bug#29931
     (http://bugs.mysql.com/29931))

   * Calling `SHOW CREATE PROCEDURE' for routines with a hyphen in the
     catalog name produced a syntax error.  (Bug#29526
     (http://bugs.mysql.com/29526))

   * Connecting to a MySQL server earlier than version 4.1 would raise
     a `NullException'.  (Bug#29476 (http://bugs.mysql.com/29476))

   * The availability of a MySQL server would not be reset when using
     pooled connections (`pooling=true'). This would lead to the server
     being reported as unavailable, even if the server become available
     while the application was still running.  (Bug#29409
     (http://bugs.mysql.com/29409))

   * A `FormatException' error would be raised if a parameter had not
     been found, instead of `Resources.ParameterMustBeDefined'.
     (Bug#29312 (http://bugs.mysql.com/29312))

   * An exception would be thrown when using the Manage Role
     functionality within the web administrator to assign a role to a
     user.  (Bug#29236 (http://bugs.mysql.com/29236))

   * Using the membership/role providers when `validationKey' or
     `decryptionKey' parameters are set to `AutoGenerate', an exception
     would be raised when accessing the corresponding values.
     (Bug#29235 (http://bugs.mysql.com/29235))

   * Certain operations would not check the `UsageAdvisor' setting,
     causing log messages from the Usage Advisor even when it was
     disabled.  (Bug#29124 (http://bugs.mysql.com/29124))

   * Using the same connection string multiple times would result in
     `Database=DBNAME' appearing multiple times in the resulting string.
     (Bug#29123 (http://bugs.mysql.com/29123))

   * _Visual Studio Plugin_: Adding a new query based on a stored
     procedure that uses the `SELECT' statement would terminate the
     query/TableAdapter wizard.  (Bug#29098
     (http://bugs.mysql.com/29098))

   * Using `TransactionScope' would cause an
     `InvalidOperationException'.  (Bug#28709
     (http://bugs.mysql.com/28709))


File: manual.info,  Node: connector-net-news-5-1-2,  Next: connector-net-news-5-1-1,  Prev: connector-net-news-5-1-3,  Up: connector-net-news

C.3.11 Changes in MySQL Connector/NET 5.1.2 (18 June 2007)
----------------------------------------------------------

This is a new Beta development release, fixing recently discovered bugs.

Bugs fixed:

   * Log messages would be truncated to 300 bytes.  (Bug#28706
     (http://bugs.mysql.com/28706))

   * Creating a user would fail due to the application name being set
     incorrectly.  (Bug#28648 (http://bugs.mysql.com/28648))

   * _Visual Studio Plugin_: Adding a new query based on a stored
     procedure that used a `UPDATE', `INSERT' or `DELETE' statement
     would terminate the query/TableAdapter wizard.  (Bug#28536
     (http://bugs.mysql.com/28536))

   * _Visual Studio Plugin_: Query Builder would fail to show
     `TINYTEXT' columns, and any columns listed after a `TINYTEXT'
     column correctly.  (Bug#28437 (http://bugs.mysql.com/28437))

   * Accessing the results from a large query when using data
     compression in the connection would fail to return all the data.
     (Bug#28204 (http://bugs.mysql.com/28204))

   * _Visual Studio Plugin_: Update commands would not be generated
     correctly when using the TableAdapter wizard.  (Bug#26347
     (http://bugs.mysql.com/26347))


File: manual.info,  Node: connector-net-news-5-1-1,  Next: connector-net-news-5-1-0,  Prev: connector-net-news-5-1-2,  Up: connector-net-news

C.3.12 Changes in MySQL Connector/NET 5.1.1 (23 May 2007)
---------------------------------------------------------

Bugs fixed:

   * Running the statement `SHOW PROCESSLIST' would return columns as
     byte arrays instead of native columns.  (Bug#28448
     (http://bugs.mysql.com/28448))

   * Installation of the Connector/NET on Windows would fail if
     VisualStudio had not already been installed.  (Bug#28260
     (http://bugs.mysql.com/28260))

   * Connector/NET would look for the wrong table when executing
     `User.IsRole().' (Bug#28251 (http://bugs.mysql.com/28251))

   * Building a connection string within a tight loop would show slow
     peformance.  (Bug#28167 (http://bugs.mysql.com/28167))

   * The `UNSIGNED' flag for parameters in a stored procedure would be
     ignored when using `MySqlCommandBuilder' to obtain the parameter
     information.  (Bug#27679 (http://bugs.mysql.com/27679))

   * Using `MySQLDataAdapter.FillSchema()' on a stored procedure would
     raise an exception: `Invalid attempt to access a field before
     calling Read()'.  (Bug#27668 (http://bugs.mysql.com/27668))

   * `DATETIME' fields from versions of MySQL bgefore 4.1 would be
     incorrectly parsed, resulting in a exception.  (Bug#23342
     (http://bugs.mysql.com/23342))

   * Fixed password property on `MySqlConnectionStringBuilder' to use
     `PasswordPropertyText' attribute. This causes dots to show instead
     of actual password text.


File: manual.info,  Node: connector-net-news-5-1-0,  Next: connector-net-news-5-0-10,  Prev: connector-net-news-5-1-1,  Up: connector-net-news

C.3.13 Changes in MySQL Connector/NET 5.1.0 (01 May 2007)
---------------------------------------------------------

Functionality added or changed:

   * Now compiles for .NET CF 2.0.

   * Rewrote stored procedure parsing code using a new SQL tokenizer.
     Really nasty procedures including nested comments are now
     supported.

   * GetSchema will now report objects relative to the currently
     selected database. What this means is that passing in null as a
     database restriction will report objects on the currently selected
     database only.

   * Added Membership and Role provider contributed by Sean Wright
     (thanks!).


File: manual.info,  Node: connector-net-news-5-0-10,  Next: connector-net-news-5-0-9,  Prev: connector-net-news-5-1-0,  Up: connector-net-news

C.3.14 Changes in MySQL Connector/NET 5.0.10 (Not yet released)
---------------------------------------------------------------

Bugs fixed:

   * Executing a command that resulted in a fatal exception did not
     close the connection.  (Bug#37991 (http://bugs.mysql.com/37991))

   * When a prepared insert query is run that contains an `UNSIGNED
     TINYINT' in the parameter list, the complete query and data that
     should be inserted is corrupted and no error is thrown.
     (Bug#37968 (http://bugs.mysql.com/37968))

   * In a .NET application MySQL Connector/NET modifies the connection
     string so that it contains several occurrences of the same option
     with different values. This is illustrated by the example that
     follows.

     The original connection string:

            host=localhost;database=test;uid=*****;pwd=*****;
            connect timeout=25; auto enlist=false;pooling=false;

     The connection string after after closing MySqlDataReader:

            host=localhost;database=test;uid=*****;pwd=*****;
            connect timeout=25;auto enlist=false;pooling=false;
            Allow User Variables=True;Allow User Variables=False;
            Allow User Variables=True;Allow User Variables=False;

     (Bug#37955 (http://bugs.mysql.com/37955))

   * When creating a connection pool, specifying an invalid IP address
     will cause the entire application to crash, instead of providing
     an exception.  (Bug#36432 (http://bugs.mysql.com/36432))

   * GetSchema did not work correctly when querying for a collection,
     if using a non-English locale.  (Bug#35459
     (http://bugs.mysql.com/35459))

   * When reading back a stored double or single value using the .NET
     provider, the value had less precision than the one stored.
     (Bug#33322 (http://bugs.mysql.com/33322))


File: manual.info,  Node: connector-net-news-5-0-9,  Next: connector-net-news-5-0-8,  Prev: connector-net-news-5-0-10,  Up: connector-net-news

C.3.15 Changes in MySQL Connector/NET 5.0.9 (Not yet released)
--------------------------------------------------------------

Bugs fixed:

   * The DbCommandBuilder.QuoteIdentifer method was not implemented.
     (Bug#35492 (http://bugs.mysql.com/35492))

   * Setting the size of a string parameter after the value could cause
     an exception.  (Bug#32094 (http://bugs.mysql.com/32094))

   * Creation of parameter objects with non-input direction using a
     constructor would fail. This was cause by some old legacy code
     preventing their use.  (Bug#32093 (http://bugs.mysql.com/32093))

   * A date string could be returned incorrectly by
     `MySqlDataTime.ToString()' when the date returned by MySQL was
     `0000-00-00 00:00:00'.  (Bug#32010 (http://bugs.mysql.com/32010))

   * A syntax error in a set of batch statements could leave the data
     adapter in a state that appears hung.  (Bug#31930
     (http://bugs.mysql.com/31930))

   * Installing over a failed uninstall of a previous version could
     result in multiple clients being registered in the
     `machine.config'. This would prevent certain aspects of the MySQL
     connection within Visual Studio to work properly.  (Bug#31731
     (http://bugs.mysql.com/31731))

   * Data cached from the connection string could return invalid
     information because the internal routines were not using
     case-sensitive semantics. This lead to updated connection string
     options not being recognized if they were of a different case than
     the existing cached values.  (Bug#31433
     (http://bugs.mysql.com/31433))

   * Column name metadata was not using the character set as deifned
     within the connection string being used.  (Bug#31185
     (http://bugs.mysql.com/31185))

   * Memory usage could increase and decrease significantly when
     updating or inserting a large number of rows.  (Bug#31090
     (http://bugs.mysql.com/31090))

   * Commands executed from within the state change handeler would fail
     with a `NULL' exception.  (Bug#30964 (http://bugs.mysql.com/30964))

   * When running a stored procedure multiple times on the same
     connection, the memory usage could increase indefinitely.
     (Bug#30116 (http://bugs.mysql.com/30116))

   * The server error code was not updated in the `Data[]' hash, which
     prevented `DbProviderFactory' users from accessing the server
     error code.  (Bug#27436 (http://bugs.mysql.com/27436))

   * Changing the connection string of a connection to one that changes
     the parameter marker after the connection had been assigned to a
     command but before the connection is opened could cause parameters
     to not be found.  (Bug#13991 (http://bugs.mysql.com/13991))


File: manual.info,  Node: connector-net-news-5-0-8,  Next: connector-net-news-5-0-7,  Prev: connector-net-news-5-0-9,  Up: connector-net-news

C.3.16 Changes in MySQL Connector/NET 5.0.8 (21 August 2007)
------------------------------------------------------------

*Note*:

This version introduces a new installer technology.

Bugs fixed:

   * Extracting data through XML functions within a query returns the
     data as `System.Byte[]'. This was due to Connector/NET incorrectly
     identifying `BLOB' fields as binary, rather than text.  (Bug#30233
     (http://bugs.mysql.com/30233))

   * An incorrect `ConstraintException' could be raised on an `INSERT'
     when adding rows to a table with a multiple-column unique key
     index.  (Bug#30204 (http://bugs.mysql.com/30204))

   * A `DATE' field would be updated with a date/time value, causing a
     `MySqlDataAdapter.Update()' exception.  (Bug#30077
     (http://bugs.mysql.com/30077))

   * Fixed bug where Connector/Net was hand building some date time
     patterns rather than using the patterns provided under
     CultureInfo. This caused problems with some calendars that do not
     support the same ranges as Gregorian..  (Bug#29931
     (http://bugs.mysql.com/29931))

   * Calling `SHOW CREATE PROCEDURE' for routines with a hyphen in the
     catalog name produced a syntax error.  (Bug#29526
     (http://bugs.mysql.com/29526))

   * The availability of a MySQL server would not be reset when using
     pooled connections (`pooling=true'). This would lead to the server
     being reported as unavailable, even if the server become available
     while the application was still running.  (Bug#29409
     (http://bugs.mysql.com/29409))

   * A `FormatException' error would be raised if a parameter had not
     been found, instead of `Resources.ParameterMustBeDefined'.
     (Bug#29312 (http://bugs.mysql.com/29312))

   * Certain operations would not check the `UsageAdvisor' setting,
     causing log messages from the Usage Advisor even when it was
     disabled.  (Bug#29124 (http://bugs.mysql.com/29124))

   * Using the same connection string multiple times would result in
     `Database=DBNAME' appearing multiple times in the resulting string.
     (Bug#29123 (http://bugs.mysql.com/29123))

   * Log messages would be truncated to 300 bytes.  (Bug#28706
     (http://bugs.mysql.com/28706))

   * Accessing the results from a large query when using data
     compression in the connection will fail to return all the data.
     (Bug#28204 (http://bugs.mysql.com/28204))

   * Fixed problem where `MySqlConnection.BeginTransaction' checked the
     drivers status var before checking if the connection was open.
     The result was that the driver could report an invalid condition
     on a previously opened connection.

   * Fixed problem where we were not closing prepared statement handles
     when commands are disposed. This could lead to using up all
     prepared statement handles on the server.

   * Fixed the database schema collection so that it works on servers
     that are not properly respecting the `lower_case_table_names'
     setting.

   * Fixed problem where any attempt to not read all the records
     returned from a select where each row of the select is greater
     than 1024 bytes would hang the driver.

   * Fixed problem where a command timing out just after it actually
     finished would cause an exception to be thrown on the command
     timeout thread which would then be seen as an unhandled exception.

   * Fixed some serious issues with command timeout and cancel that
     could present as exceptions about thread ownership. The issue was
     that not all queries cancel the same. Some produce resultsets
     while others don't. ExecuteReader had to be changed to check for
     this.


File: manual.info,  Node: connector-net-news-5-0-7,  Next: connector-net-news-5-0-6,  Prev: connector-net-news-5-0-8,  Up: connector-net-news

C.3.17 Changes in MySQL Connector/NET 5.0.7 (18 May 2007)
---------------------------------------------------------

Bugs fixed:

   * Running the statement `SHOW PROCESSLIST' would return columns as
     byte arrays instead of native columns.  (Bug#28448
     (http://bugs.mysql.com/28448))

   * Building a connection string within a tight loop would show slow
     peformance.  (Bug#28167 (http://bugs.mysql.com/28167))

   * Using logging (with the `logging=true' parameter to the connection
     string) would not generate a log file.  (Bug#27765
     (http://bugs.mysql.com/27765))

   * The `UNSIGNED' flag for parameters in a stored procedure would be
     ignored when using `MySqlCommandBuilder' to obtain the parameter
     information.  (Bug#27679 (http://bugs.mysql.com/27679))

   * Using `MySQLDataAdapter.FillSchema()' on a stored procedure would
     raise an exception: `Invalid attempt to access a field before
     calling Read()'.  (Bug#27668 (http://bugs.mysql.com/27668))

   * If you close an open connection with an active transaction, the
     transaction is not automatically rolled back.  (Bug#27289
     (http://bugs.mysql.com/27289))

   * When cloning an open `MySqlClient.MySqlConnection' with the
     `Persist Security Info=False' option set, the cloned connection is
     not usable because the security information has not been cloned.
     (Bug#27269 (http://bugs.mysql.com/27269))

   * Enlisting a null transaction would affect the current connection
     object, such that further enlistment operations to the transaction
     are not possible.  (Bug#26754 (http://bugs.mysql.com/26754))

   * Attempting to change the the `Connection Protocol' property within
     a `PropertyGrid' control would raise an exception.  (Bug#26472
     (http://bugs.mysql.com/26472))

   * The `characterset' property would not be identified during a
     connection (also affected Visual Studion Plugin).  (Bug#26147
     (http://bugs.mysql.com/26147), Bug#27240
     (http://bugs.mysql.com/27240))

   * The `CreateFormat' column of the `DataTypes' collection did not
     contain a format specification for creating a new column type.
     (Bug#25947 (http://bugs.mysql.com/25947))

   * `DATETIME' fields from versions of MySQL bgefore 4.1 would be
     incorrectly parsed, resulting in a exception.  (Bug#23342
     (http://bugs.mysql.com/23342))


File: manual.info,  Node: connector-net-news-5-0-6,  Next: connector-net-news-5-0-5,  Prev: connector-net-news-5-0-7,  Up: connector-net-news

C.3.18 Changes in MySQL Connector/NET 5.0.6 (22 March 2007)
-----------------------------------------------------------

Bugs fixed:

   * Publisher listed in "Add/Remove Programs" is not consistent with
     other MySQL products.  (Bug#27253 (http://bugs.mysql.com/27253))

   * `DESCRIBE ....' SQL statement returns byte arrays rather than data
     on MySQL versions older than 4.1.15.  (Bug#27221
     (http://bugs.mysql.com/27221))

   * `cmd.Parameters.RemoveAt("Id")' will cause an error if the last
     item is requested.  (Bug#27187 (http://bugs.mysql.com/27187))

   * `MySqlParameterCollection' and parameters added with `Insert'
     method can not be retrieved later using `ParameterName'.
     (Bug#27135 (http://bugs.mysql.com/27135))

   * Exception thrown when using large values in `UInt64' parameters.
     (Bug#27093 (http://bugs.mysql.com/27093))

   * MySQL Visual Studio Plugin 1.1.2 does not work with Connector/Net
     5.0.5.  (Bug#26960 (http://bugs.mysql.com/26960))


File: manual.info,  Node: connector-net-news-5-0-5,  Next: connector-net-news-5-0-4,  Prev: connector-net-news-5-0-6,  Up: connector-net-news

C.3.19 Changes in MySQL Connector/NET 5.0.5 (07 March 2007)
-----------------------------------------------------------

Functionality added or changed:

   * Reverted behavior that required parameter names to start with the
     parameter marker. We apologize for this back and forth but we
     mistakenly changed the behavior to not match what `SqlClient'
     supports. We now support using either syntax for adding parameters
     however we also respond exactly like `SqlClient' in that if you
     ask for the index of a parameter using a syntax different from
     when you added the parameter, the result will be -1.

   * Assembly now properly appears in the Visual Studio 2005 Add/Remove
     Reference dialog.

   * Fixed problem that prevented use of `SchemaOnly' or `SingleRow'
     command behaviors with stored procedures or prepared statements.

   * Added `MySqlParameterCollection.AddWithValue' and marked the
     `Add(name, value)' method as obsolete.

   * Return parameters created with DeriveParameters now have the name
     `RETURN_VALUE'.

   * Fixed problem with parameter name hashing where the hashes were
     not getting updated when parameters were removed from the
     collection.

   * Fixed problem with calling stored functions when a return
     parameter was not given.

   * Added `Use Procedure Bodies' connection string option to allow
     calling procedures without using procedure metadata.

Bugs fixed:

   * `MySqlConnection.GetSchema' fails with `NullReferenceException'
     for Foreign Keys.  (Bug#26660 (http://bugs.mysql.com/26660))

   * Connector/NET would fail to install under Windows Vista.
     (Bug#26430 (http://bugs.mysql.com/26430))

   * Opening a connection would be slow due to hostname lookup.
     (Bug#26152 (http://bugs.mysql.com/26152))

   * Incorrect values/formats would be applied when the `OldSyntax'
     connection string option was used.  (Bug#25950
     (http://bugs.mysql.com/25950))

   * Registry would be incorrectly populated with installation
     locations.  (Bug#25928 (http://bugs.mysql.com/25928))

   * Times with negative values would be returned incorrectly.
     (Bug#25912 (http://bugs.mysql.com/25912))

   * Returned data types of a `DataTypes' collection do not contain the
     right correctl CLR Datatype.  (Bug#25907
     (http://bugs.mysql.com/25907))

   * `GetSchema' and `DataTypes' would throw an exception due to an
     incorrect table name.  (Bug#25906 (http://bugs.mysql.com/25906))

   * `MySqlConnection' throws an exception when connecting to MySQL
     v4.1.7.  (Bug#25726 (http://bugs.mysql.com/25726))

   * `SELECT' did not work correctly when using a `WHERE' clause
     containing a UTF-8 string.  (Bug#25651
     (http://bugs.mysql.com/25651))

   * When closing and then re-opening a connection to a database, the
     character set specification is lost.  (Bug#25614
     (http://bugs.mysql.com/25614))

   * Filling a table schema through a stored procedure triggers a
     runtime error.  (Bug#25609 (http://bugs.mysql.com/25609))

   * `BINARY' and `VARBINARY' columns would be returned as a string,
     not binary, datatype.  (Bug#25605 (http://bugs.mysql.com/25605))

   * A critical `ConnectionPool' error would result in repeated
     `System.NullReferenceException'.  (Bug#25603
     (http://bugs.mysql.com/25603))

   * The `UpdateRowSource.FirstReturnedRecord' method does not work.
     (Bug#25569 (http://bugs.mysql.com/25569))

   * When connecting to a MySQL Server earlier than version 4.1, the
     connection would hang when reading data.  (Bug#25458
     (http://bugs.mysql.com/25458))

   * Using `ExecuteScalar()' with more than one query, where one query
     fails, will hang the connection.  (Bug#25443
     (http://bugs.mysql.com/25443))

   * When a `MySqlConversionException' is raised on a remote object,
     the client application would receive a `SerializationException'
     instead.  (Bug#24957 (http://bugs.mysql.com/24957))

   * When connecting to a server, the return code from the connection
     could be zero, even though the hostname was incorrect.  (Bug#24802
     (http://bugs.mysql.com/24802))

   * High CPU utilization would be experienced when there is no idle
     connection waiting when using pooled connections through
     `MySqlPool.GetConnection'.  (Bug#24373
     (http://bugs.mysql.com/24373))

   * Connector/NET would not compile properly when used with Mono 1.2.
     (Bug#24263 (http://bugs.mysql.com/24263))

   * Applications would crash when calling with `CommandType' set to
     `StoredProcedure'.


File: manual.info,  Node: connector-net-news-5-0-4,  Next: connector-net-news-5-0-3,  Prev: connector-net-news-5-0-5,  Up: connector-net-news

C.3.20 Changes in MySQL Connector/NET 5.0.4 (Not released)
----------------------------------------------------------

This is a new Beta development release, fixing recently discovered bugs.


File: manual.info,  Node: connector-net-news-5-0-3,  Next: connector-net-news-5-0-2,  Prev: connector-net-news-5-0-4,  Up: connector-net-news

C.3.21 Changes in MySQL Connector/NET 5.0.3 (05 January 2007)
-------------------------------------------------------------

Functionality added or changed:

   * Usage Advisor has been implemented. The Usage Advisor checks your
     queries and will report if you are using the connection
     inefficiently.

   * PerfMon hooks have been added to monitor the stored procedure
     cache hits and misses.

   * The `MySqlCommand' object now supports asynchronous query methods.
     This is implemented useg the `BeginExecuteNonQuery' and
     `EndExecuteNonQuery' methods.

   * Metadata from storaed procedures and stored function execution are
     cached.

   * The `CommandBuilder.DeriveParameters' function has been updated to
     the procedure cache.

   * The `ViewColumns' `GetSchema' collection has been updated.

   * Improved speed and performance by re-architecting certain sections
     of the code.

   * Support for the embedded server and client library have been
     removed from this release. Support will be added back to a later
     release.

   * The ShapZipLib library has been replaced with the deflate support
     provided within .NET 2.0.

   * SSL support has been updated.

Bugs fixed:

   * Additional text added to error message (Bug#25178
     (http://bugs.mysql.com/25178))

   * An exception would be raised, or the process would hang, if
     `SELECT' privileges on a database were not granted and a stored
     procedure was used.  (Bug#25033 (http://bugs.mysql.com/25033))

   * When adding parameter objects to a command object, if the
     parameter direction is set to `ReturnValue' before the parameter
     is added to the command object then when the command is executed
     it throws an error.  (Bug#25013 (http://bugs.mysql.com/25013))

   * Using `Driver.IsTooOld()' would return the wrong value.
     (Bug#24661 (http://bugs.mysql.com/24661))

   * When using a `DbNull.Value' as the value for a parameter value,
     and then later setting a specific value type, the command would
     fail with an exception because the wrong type was implied from the
     `DbNull.Value'.  (Bug#24565 (http://bugs.mysql.com/24565))

   * Stored procedure executions are not thread safe.  (Bug#23905
     (http://bugs.mysql.com/23905))

   * Deleting a connection to a disconnected server when using the
     Visual Studio Plugin would cause an assertion failure.  (Bug#23687
     (http://bugs.mysql.com/23687))

   * Nested transactions (which are unsupported)do not raise an error
     or warning.  (Bug#22400 (http://bugs.mysql.com/22400))


File: manual.info,  Node: connector-net-news-5-0-2,  Next: connector-net-news-5-0-1,  Prev: connector-net-news-5-0-3,  Up: connector-net-news

C.3.22 Changes in MySQL Connector/NET 5.0.2 (06 November 2006)
--------------------------------------------------------------

Functionality added or changed:

   * An `Ignore Prepare' option has been added to the connection string
     options. If enabled, prepared statements will be disabled
     application-wide. The default for this option is true.

   * Implemented a stored procedure cache. By default, the connector
     caches the metadata for the last 25 procedures that are seen.  You
     can change the numbver of procedures that are cacheds by using the
     `procedure cache' connection string.

   * *Important change:* Due to a number of issues with the use of
     server-side prepared statements, Connector/NET 5.0.2 has disabled
     their use by default. The disabling of server-side prepared
     statements does not affect the operation of the connector in any
     way.

     To enable server-side prepared statements you must add the
     following configuration property to your connector string
     properties:

          ignore prepare=false

     The default value of this property is true.

Bugs fixed:

   * One system where IPv6 was enabled, Connector/NET would incorrectly
     resolve hostnames.  (Bug#23758 (http://bugs.mysql.com/23758))

   * Column names with accented characters were not parsed properly
     causing malformed column names in result sets.  (Bug#23657
     (http://bugs.mysql.com/23657))

   * An exception would be thrown when calling `GetSchemaTable' and
     `fields' was null.  (Bug#23538 (http://bugs.mysql.com/23538))

   * A `System.FormatException' exception would be raised when invoking
     a stored procedure with an `ENUM' input parameter.  (Bug#23268
     (http://bugs.mysql.com/23268))

   * During installation, an antivirus error message would be raised
     (indicating a malicious script problem).  (Bug#23245
     (http://bugs.mysql.com/23245))

   * Creating a connection through the Server Explorer when using the
     Visual Studio Plugin would fail. The installer for the Visual
     Studio Plugin has been updated to ensure that Connector/NET 5.0.2
     must be installed.  (Bug#23071 (http://bugs.mysql.com/23071))

   * Using Windows Vista (RC2) as a non-privileged user would raise a
     `Registry key 'Global' access denied'.  (Bug#22882
     (http://bugs.mysql.com/22882))

   * Within Mono, using the `PreparedStatement' interface could result
     in an error due to a `BitArray' copying error.  (Bug#18186
     (http://bugs.mysql.com/18186))

   * Connector/NET did not work as a data source for the
     `SqlDataSource' object used by ASP.NET 2.0.  (Bug#16126
     (http://bugs.mysql.com/16126))


File: manual.info,  Node: connector-net-news-5-0-1,  Next: connector-net-news-5-0-0,  Prev: connector-net-news-5-0-2,  Up: connector-net-news

C.3.23 Changes in MySQL Connector/NET 5.0.1 (01 October 2006)
-------------------------------------------------------------

Bugs fixed:

   * Connector/NET on a Tukish operating system, may fail to execute
     certain SQL statements correctly.  (Bug#22452
     (http://bugs.mysql.com/22452))

   * Starting a transaction on a connection created by
     `MySql.Data.MySqlClient.MySqlClientFactory', using
     `BeginTransaction' without specifying an isolation level, causes
     the SQL statement to fail with a syntax error.  (Bug#22042
     (http://bugs.mysql.com/22042))

   * The `MySqlexception' class is now derived from the `DbException'
     class.  (Bug#21874 (http://bugs.mysql.com/21874))

   * The `#' would not be accepted within column/table names, even
     though it was valid.  (Bug#21521 (http://bugs.mysql.com/21521))

   * You can now install the Connector/NET MSI package from the command
     line using the `/passive', `/quiet', `/q' options.  (Bug#19994
     (http://bugs.mysql.com/19994))

   * Submitting an empty string to a command object through `prepare'
     raises an `System.IndexOutOfRangeException', rather than a
     Connector/Net exception.  (Bug#18391 (http://bugs.mysql.com/18391))

   * Using `ExecuteScalar' with a datetime field, where the value of
     the field is "0000-00-00 00:00:00", a `MySqlConversionException'
     exception would be raised.  (Bug#11991
     (http://bugs.mysql.com/11991))

   * An `MySql.Data.Types.MySqlConversionException' would be raised
     when trying to update a row that contained a date field, where the
     date field contained a zero value (0000-00-00 00:00:00).
     (Bug#9619 (http://bugs.mysql.com/9619))

   * Executing multiple queries as part of a transaction returns `There
     is already an openDataReader associated with this Connection which
     must be closed first'.  (Bug#7248 (http://bugs.mysql.com/7248))

   * Incorrect field/data lengths could be returned for `VARCHAR' UTF8
     columns. Bug (#14592)


File: manual.info,  Node: connector-net-news-5-0-0,  Next: connector-net-news-1-0-11,  Prev: connector-net-news-5-0-1,  Up: connector-net-news

C.3.24 Changes in MySQL Connector/NET 5.0.0 (08 August 2006)
------------------------------------------------------------

Functionality added or changed:

   * Replaced use of ICSharpCode with .NET 2.0 internal deflate support.

   * Refactored test suite to test all protocols in a single pass.

   * Added usage advisor warnings for requesting column values by the
     wrong type.

   * Reimplemented PacketReader/PacketWriter support into MySqlStream
     class.

   * Reworked connection string classes to be simpler and faster.

   * Added procedure metadata caching.

   * Added internal implemention of SHA1 so we don't have to distribute
     the OpenNetCF on mobile devices.

   * Implemented MySqlClientFactory class.

   * Added perfmon hooks for stored procedure cache hits and misses.

   * Implemented classes and interfaces for ADO.Net 2.0 support.

   * Added Async query methods.

   * Implemented Usage Advisor.

   * Completely refactored how column values are handled to avoid
     boxing in some cases.

   * Implemented MySqlConnectionBuilder class.

Bugs fixed:

   * CommandText: Question mark in comment line is being parsed as a
     parameter.  (Bug#6214 (http://bugs.mysql.com/6214))


File: manual.info,  Node: connector-net-news-1-0-11,  Next: connector-net-news-1-0-10,  Prev: connector-net-news-5-0-0,  Up: connector-net-news

C.3.25 Changes in MySQL Connector/NET 1.0.11 (Not yet released)
---------------------------------------------------------------

Bugs fixed:

   * Attempting to utilize MySQL Connector .Net version 1.0.10 throws a
     fatal exception under Mono when pooling is enabled.  (Bug#33682
     (http://bugs.mysql.com/33682))

   * Setting the size of a string parameter after the value could cause
     an exception.  (Bug#32094 (http://bugs.mysql.com/32094))

   * Creation of parameter objects with non-input direction using a
     constructor would fail. This was cause by some old legacy code
     preventing their use.  (Bug#32093 (http://bugs.mysql.com/32093))

   * Memory usage could increase and decrease significantly when
     updating or inserting a large number of rows.  (Bug#31090
     (http://bugs.mysql.com/31090))

   * Commands executed from within the state change handeler would fail
     with a `NULL' exception.  (Bug#30964 (http://bugs.mysql.com/30964))

   * Extracting data through XML functions within a query returns the
     data as `System.Byte[]'. This was due to Connector/NET incorrectly
     identifying `BLOB' fields as binary, rather than text.  (Bug#30233
     (http://bugs.mysql.com/30233))

   * Using compression in the MySQL connection with Connector/NET would
     be slower than using native (uncompressed) communication.
     (Bug#27865 (http://bugs.mysql.com/27865))

   * Changing the connection string of a connection to one that changes
     the parameter marker after the connection had been assigned to a
     command but before the connection is opened could cause parameters
     to not be found.  (Bug#13991 (http://bugs.mysql.com/13991))


File: manual.info,  Node: connector-net-news-1-0-10,  Next: connector-net-news-1-0-9,  Prev: connector-net-news-1-0-11,  Up: connector-net-news

C.3.26 Changes in MySQL Connector/NET 1.0.10 (24 August 2007)
-------------------------------------------------------------

Bugs fixed:

   * An incorrect `ConstraintException' could be raised on an `INSERT'
     when adding rows to a table with a multiple-column unique key
     index.  (Bug#30204 (http://bugs.mysql.com/30204))

   * The availability of a MySQL server would not be reset when using
     pooled connections (`pooling=true'). This would lead to the server
     being reported as unavailable, even if the server become available
     while the application was still running.  (Bug#29409
     (http://bugs.mysql.com/29409))

   * Publisher listed in "Add/Remove Programs" is not consistent with
     other MySQL products.  (Bug#27253 (http://bugs.mysql.com/27253))

   * `MySqlParameterCollection' and parameters added with `Insert'
     method can not be retrieved later using `ParameterName'.
     (Bug#27135 (http://bugs.mysql.com/27135))

   * `BINARY' and `VARBINARY' columns would be returned as a string,
     not binary, datatype.  (Bug#25605 (http://bugs.mysql.com/25605))

   * A critical `ConnectionPool' error would result in repeated
     `System.NullReferenceException'.  (Bug#25603
     (http://bugs.mysql.com/25603))

   * When a `MySqlConversionException' is raised on a remote object,
     the client application would receive a `SerializationException'
     instead.  (Bug#24957 (http://bugs.mysql.com/24957))

   * High CPU utilization would be experienced when there is no idle
     connection waiting when using pooled connections through
     `MySqlPool.GetConnection'.  (Bug#24373
     (http://bugs.mysql.com/24373))


File: manual.info,  Node: connector-net-news-1-0-9,  Next: connector-net-news-1-0-8,  Prev: connector-net-news-1-0-10,  Up: connector-net-news

C.3.27 Changes in MySQL Connector/NET 1.0.9 (02 February 2007)
--------------------------------------------------------------

Functionality added or changed:

   * The ICSharpCode ZipLib is no longer used by the Connector, and is
     no longer distributed with it.

   * *Important change:* Binaries for .NET 1.0 are no longer supplied
     with this release. If you need support for .NET 1.0, you must
     build from source.

   * Improved `CommandBuilder.DeriveParameters' to first try and use
     the procedure cache before querying for the stored procedure
     metadata. Return parameters created with `DeriveParameters' now
     have the name `RETURN_VALUE'.

   * An `Ignore Prepare' option has been added to the connection string
     options. If enabled, prepared statements will be disabled
     application-wide. The default for this option is true.

   * Implemented a stored procedure cache. By default, the connector
     caches the metadata for the last 25 procedures that are seen.  You
     can change the numbver of procedures that are cacheds by using the
     `procedure cache' connection string.

   * *Important change:* Due to a number of issues with the use of
     server-side prepared statements, Connector/NET 5.0.2 has disabled
     their use by default. The disabling of server-side prepared
     statements does not affect the operation of the connector in any
     way.

     To enable server-side prepared statements you must add the
     following configuration property to your connector string
     properties:

          ignore prepare=false

     The default value of this property is true.

Bugs fixed:

   * Times with negative values would be returned incorrectly.
     (Bug#25912 (http://bugs.mysql.com/25912))

   * `MySqlConnection' throws a `NullReferenceException' and
     `ArgumentNullException' when connecting to MySQL v4.1.7.
     (Bug#25726 (http://bugs.mysql.com/25726))

   * `SELECT' did not work correctly when using a `WHERE' clause
     containing a UTF-8 string.  (Bug#25651
     (http://bugs.mysql.com/25651))

   * When closing and then re-opening a connection to a database, the
     character set specification is lost.  (Bug#25614
     (http://bugs.mysql.com/25614))

   * Trying to fill a table schema through a stored procedure triggers
     a runtime error.  (Bug#25609 (http://bugs.mysql.com/25609))

   * Using `ExecuteScalar()' with more than one query, where one query
     fails, will hang the connection.  (Bug#25443
     (http://bugs.mysql.com/25443))

   * Additional text added to error message.  (Bug#25178
     (http://bugs.mysql.com/25178))

   * When adding parameter objects to a command object, if the
     parameter direction is set to `ReturnValue' before the parameter
     is added to the command object then when the command is executed
     it throws an error.  (Bug#25013 (http://bugs.mysql.com/25013))

   * When connecting to a server, the return code from the connection
     could be zero, even though the hostname was incorrect.  (Bug#24802
     (http://bugs.mysql.com/24802))

   * Using `Driver.IsTooOld()' would return the wrong value.
     (Bug#24661 (http://bugs.mysql.com/24661))

   * When using a `DbNull.Value' as the value for a parameter value,
     and then later setting a specific value type, the command would
     fail with an exception because the wrong type was implied from the
     `DbNull.Value'.  (Bug#24565 (http://bugs.mysql.com/24565))

   * Stored procedure executions are not thread safe.  (Bug#23905
     (http://bugs.mysql.com/23905))

   * The `CommandBuilder' would mistakenly add insert parameters for a
     table column with auto incrementation enabled.  (Bug#23862
     (http://bugs.mysql.com/23862))

   * One system where IPv6 was enabled, Connector/NET would incorrectly
     resolve hostnames.  (Bug#23758 (http://bugs.mysql.com/23758))

   * Nested transactions do not raise an error or warning.  (Bug#22400
     (http://bugs.mysql.com/22400))

   * An `System.OverflowException' would be raised when accessing a
     varchar field over 255 bytes. Bug (#23749)

   * Within Mono, using the `PreparedStatement' interface could result
     in an error due to a `BitArray' copying error. (Bug 18186)


File: manual.info,  Node: connector-net-news-1-0-8,  Next: connector-net-news-1-0-7,  Prev: connector-net-news-1-0-9,  Up: connector-net-news

C.3.28 Changes in MySQL Connector/NET 1.0.8 (20 October 2006)
-------------------------------------------------------------

Functionality added or changed:

   * Stored procedures are now cached.

   * The method for retrieving stored procedured metadata has been
     changed so that users without `SELECT' privileges on the
     `mysql.proc' table can use a stored procedure.

Bugs fixed:

   * Connector/NET on a Tukish operating system, may fail to execute
     certain SQL statements correctly.  (Bug#22452
     (http://bugs.mysql.com/22452))

   * The `#' would not be accepted within column/table names, even
     though it was valid.  (Bug#21521 (http://bugs.mysql.com/21521))

   * Calling Close on a connection after calling a stored procedure
     would trigger a `NullReferenceException'.  (Bug#20581
     (http://bugs.mysql.com/20581))

   * You can now install the Connector/NET MSI package from the command
     line using the `/passive', `/quiet', `/q' options.  (Bug#19994
     (http://bugs.mysql.com/19994))

   * The DiscoverParameters function would fail when a stored procedure
     used a `NUMERIC' parameter type.  (Bug#19515
     (http://bugs.mysql.com/19515))

   * When running a query that included a date comparison, a DateReader
     error would be raised.  (Bug#19481 (http://bugs.mysql.com/19481))

   * `IDataRecord.GetString' would raise `NullPointerException' for
     null values in returned rows. Method now throws
     `SqlNullValueException'.  (Bug#19294 (http://bugs.mysql.com/19294))

   * Parameter substitution in queries where the order of parameters
     and table fields did not match would substitute incorrect values.
     (Bug#19261 (http://bugs.mysql.com/19261))

   * Submitting an empty string to a command object through `prepare'
     raises an `System.IndexOutOfRangeException', rather than a
     Connector/Net exception.  (Bug#18391 (http://bugs.mysql.com/18391))

   * An exception would be raised when using an output parameter to a
     `System.String' value.  (Bug#17814 (http://bugs.mysql.com/17814))

   * CHAR type added to MySqlDbType.  (Bug#17749
     (http://bugs.mysql.com/17749))

   * A `SELECT' query on a table with a date with a value of
     `'0000-00-00'' would hang the application.  (Bug#17736
     (http://bugs.mysql.com/17736))

   * The CommandBuilder ignored Unsigned flag at Parameter creation.
     (Bug#17375 (http://bugs.mysql.com/17375))

   * When working with multiple threads, character set initialization
     would generate errors.  (Bug#17106 (http://bugs.mysql.com/17106))

   * When using an unsigned 64-bit integer in a stored procedure, the
     unsigned bit would be lost stored.  (Bug#16934
     (http://bugs.mysql.com/16934))

   * `DataReader' would show the value of the previous row (or last row
     with non-null data) if the current row contained a `datetime'
     field with a null value.  (Bug#16884 (http://bugs.mysql.com/16884))

   * Unsigned data types were not properly supported.  (Bug#16788
     (http://bugs.mysql.com/16788))

   * The connection string parser did not allow single or double quotes
     in the password.  (Bug#16659 (http://bugs.mysql.com/16659))

   * The `MySqlDateTime' class did not contain constructors.
     (Bug#15112 (http://bugs.mysql.com/15112))

   * Called `MySqlCommandBuilder.DeriveParameters' for a stored
     procedure that has no paramers would cause an application crash.
     (Bug#15077 (http://bugs.mysql.com/15077))

   * Using `ExecuteScalar' with a datetime field, where the value of
     the field is "0000-00-00 00:00:00", a `MySqlConversionException'
     exception would be raised.  (Bug#11991
     (http://bugs.mysql.com/11991))

   * An `MySql.Data.Types.MySqlConversionException' would be raised
     when trying to update a row that contained a date field, where the
     date field contained a zero value (0000-00-00 00:00:00).
     (Bug#9619 (http://bugs.mysql.com/9619))

   * When using `MySqlDataAdapter', connections to a MySQL server may
     remain open and active, even though the use of the connection has
     been completed and the data received.  (Bug#8131
     (http://bugs.mysql.com/8131))

   * Executing multiple queries as part of a transaction returns `There
     is already an openDataReader associated with this Connection which
     must be closed first'.  (Bug#7248 (http://bugs.mysql.com/7248))

   * Incorrect field/data lengths could be returned for `VARCHAR' UTF8
     columns. Bug (#14592)


File: manual.info,  Node: connector-net-news-1-0-7,  Next: connector-net-news-1-0-6,  Prev: connector-net-news-1-0-8,  Up: connector-net-news

C.3.29 Changes in MySQL Connector/NET 1.0.7 (21 November 2005)
--------------------------------------------------------------

Bugs fixed:

   * Unsigned `tinyint' (NET byte) would lead to and incorrectly
     determined parameter type from the parameter value.  (Bug#18570
     (http://bugs.mysql.com/18570))

   * A `#42000Query was empty' exception occurred when executing a
     query built with `MySqlCommandBuilder', if the query string ended
     with a semicolon.  (Bug#14631 (http://bugs.mysql.com/14631))

   * The parameter collection object's `Add()' method added parameters
     to the list without first checking to see whether they already
     existed. Now it updates the value of the existing parameter object
     if it exists.  (Bug#13927 (http://bugs.mysql.com/13927))

   * Added support for the `cp932' character set.  (Bug#13806
     (http://bugs.mysql.com/13806))

   * Calling a stored procedure where a parameter contained special
     characters (such as `'@'') would produce an exception. Note that
     `ANSI_QUOTES' had to be enabled to make this possible.  (Bug#13753
     (http://bugs.mysql.com/13753))

   * The `Ping()' method did not update the `State' property of the
     `Connection' object.  (Bug#13658 (http://bugs.mysql.com/13658))

   * Implemented the `MySqlCommandBuilder.DeriveParameters' method that
     is used to discover the parameters for a stored procedure.
     (Bug#13632 (http://bugs.mysql.com/13632))

   * A statement that contained multiple references to the same
     parameter could not be prepared.  (Bug#13541
     (http://bugs.mysql.com/13541))


File: manual.info,  Node: connector-net-news-1-0-6,  Next: connector-net-news-1-0-5,  Prev: connector-net-news-1-0-7,  Up: connector-net-news

C.3.30 Changes in MySQL Connector/NET 1.0.6 (03 October 2005)
-------------------------------------------------------------

Bugs fixed:

   * Connector/NET 1.0.5 could not connect on Mono.  (Bug#13345
     (http://bugs.mysql.com/13345))

   * Serializing a parameter failed if the first value passed in was
     `NULL'.  (Bug#13276 (http://bugs.mysql.com/13276))

   * Field names that contained the following characters caused errors:
     `()%<>/' (Bug#13036 (http://bugs.mysql.com/13036))

   * The `nant' build sequence had problems.  (Bug#12978
     (http://bugs.mysql.com/12978))

   * The Connector/NET 1.0.5 installer would not install alongside
     Connector/NET 1.0.4.  (Bug#12835 (http://bugs.mysql.com/12835))


File: manual.info,  Node: connector-net-news-1-0-5,  Next: connector-net-news-1-0-4,  Prev: connector-net-news-1-0-6,  Up: connector-net-news

C.3.31 Changes in MySQL Connector/NET 1.0.5 (29 August 2005)
------------------------------------------------------------

Bugs fixed:

   * Connector/NET could not connect to MySQL 4.1.14.  (Bug#12771
     (http://bugs.mysql.com/12771))

   * With multiple hosts in the connection string, Connector/NET would
     not connect to the last host in the list.  (Bug#12628
     (http://bugs.mysql.com/12628))

   * The `ConnectionString' property could not be set when a
     `MySqlConnection' object was added with the designer.  (Bug#12551
     (http://bugs.mysql.com/12551), Bug#8724
     (http://bugs.mysql.com/8724))

   * The `cp1250' character set was not supported.  (Bug#11621
     (http://bugs.mysql.com/11621))

   * A call to a stored procedure caused an exception if the stored
     procedure had no parameters.  (Bug#11542
     (http://bugs.mysql.com/11542))

   * Certain malformed queries would trigger a `Connection must be
     valid and open' error message.  (Bug#11490
     (http://bugs.mysql.com/11490))

   * Trying to use a stored procedure when `Connection.Database' was
     not populated generated an exception.  (Bug#11450
     (http://bugs.mysql.com/11450))

   * Connector/NET interpreted the new decimal data type as a byte
     array.  (Bug#11294 (http://bugs.mysql.com/11294))

   * Added support to call a stored function from Connector/NET.
     (Bug#10644 (http://bugs.mysql.com/10644))

   * Connection could fail when .NET thread pool had no available
     worker threads.  (Bug#10637 (http://bugs.mysql.com/10637))

   * Calling `MySqlConnection.clone' when a connection string had not
     yet been set on the original connection would generate an error.
     (Bug#10281 (http://bugs.mysql.com/10281))

   * Decimal parameters caused syntax errors.  (Bug#10152
     (http://bugs.mysql.com/10152), Bug#11550
     (http://bugs.mysql.com/11550), Bug#10486
     (http://bugs.mysql.com/10486))

   * Parameters were not recognized when they were separated by
     linefeeds.  (Bug#9722 (http://bugs.mysql.com/9722))

   * The `MySqlCommandBuilder' class could not handle queries that
     referenced tables in a database other than the default database.
     (Bug#8382 (http://bugs.mysql.com/8382))

   * Trying to read a `TIMESTAMP' column generated an exception.
     (Bug#7951 (http://bugs.mysql.com/7951))

   * Connector/NET could not work properly with certain regional
     settings. (WL#8228)


File: manual.info,  Node: connector-net-news-1-0-4,  Next: connector-net-news-1-0-3,  Prev: connector-net-news-1-0-5,  Up: connector-net-news

C.3.32 Changes in MySQL Connector/NET 1.0.4 (20 January 2005)
-------------------------------------------------------------

Bugs fixed:

   * `MySqlReader.GetInt32' throws exception if column is unsigned.
     (Bug#7755 (http://bugs.mysql.com/7755))

   * Quote character \222 not quoted in `EscapeString'.  (Bug#7724
     (http://bugs.mysql.com/7724))

   * GetBytes is working no more.  (Bug#7704
     (http://bugs.mysql.com/7704))

   * `MySqlDataReader.GetString(index)' returns non-Null value when
     field is `Null'.  (Bug#7612 (http://bugs.mysql.com/7612))

   * Clone method bug in `MySqlCommand'.  (Bug#7478
     (http://bugs.mysql.com/7478))

   * Problem with Multiple resultsets.  (Bug#7436
     (http://bugs.mysql.com/7436))

   * `MySqlAdapter.Fill' method throws error message `Non-negative
     number required'.  (Bug#7345 (http://bugs.mysql.com/7345))

   * `MySqlCommand.Connection' returns an IDbConnection.  (Bug#7258
     (http://bugs.mysql.com/7258))

   * Calling prepare causing exception.  (Bug#7243
     (http://bugs.mysql.com/7243))

   * Fixed problem with shared memory connections.

   * Added or filled out several more topics in the API reference
     documentation.

   * Fixed another small problem with prepared statements.

   * Fixed problem that causes named pipes to not work with some blob
     functionality.


File: manual.info,  Node: connector-net-news-1-0-3,  Next: connector-net-news-1-0-2,  Prev: connector-net-news-1-0-4,  Up: connector-net-news

C.3.33 Changes in MySQL Connector/NET 1.0.3 (12 October 2004)
-------------------------------------------------------------

Bugs fixed:

   * Invalid query string when using inout parameters (Bug#7133
     (http://bugs.mysql.com/7133))

   * Inserting `DateTime' causes `System.InvalidCastException' to be
     thrown.  (Bug#7132 (http://bugs.mysql.com/7132))

   * `MySqlDateTime' in Datatables sorting by Text, not Date.
     (Bug#7032 (http://bugs.mysql.com/7032))

   * Exception stack trace lost when re-throwing exceptions.  (Bug#6983
     (http://bugs.mysql.com/6983))

   * Errors in parsing stored procedure parameters.  (Bug#6902
     (http://bugs.mysql.com/6902))

   * InvalidCast when using `DATE_ADD'-function.  (Bug#6879
     (http://bugs.mysql.com/6879))

   * Int64 Support in `MySqlCommand' Parameters.  (Bug#6863
     (http://bugs.mysql.com/6863))

   * Test suite fails with MySQL 4.0 because of case sensitivity of
     table names.  (Bug#6831 (http://bugs.mysql.com/6831))

   * `MySqlDataReader.GetChar(int i)' throws `IndexOutOfRange'
     exception.  (Bug#6770 (http://bugs.mysql.com/6770))

   * Integer "out" parameter from stored procedure returned as string.
     (Bug#6668 (http://bugs.mysql.com/6668))

   * An Open Connection has been Closed by the Host System.  (Bug#6634
     (http://bugs.mysql.com/6634))

   * Fixed Invalid character set index: 200.  (Bug#6547
     (http://bugs.mysql.com/6547))

   * Connections now do not have to give a database on the connection
     string.

   * Installer now includes options to install into GAC and create
     `Start Menu' items.

   * Fixed major problem with detecting null values when using prepared
     statements.

   * Fixed problem where multiple resultsets having different numbers
     of columns would cause a problem.

   * Added `ServerThread' property to `MySqlConnection' to expose
     server thread id.

   * Added Ping method to `MySqlConnection'.

   * Changed the name of the test suite to `MySql.Data.Tests.dll'.

   * Now `SHOW COLLATION' is used upon connection to retrieve the full
     list of charset ids.

   * Made MySQL the default named pipe name.


File: manual.info,  Node: connector-net-news-1-0-2,  Next: connector-net-news-1-0-1,  Prev: connector-net-news-1-0-3,  Up: connector-net-news

C.3.34 Changes in MySQL Connector/NET 1.0.2 (15 November 2004)
--------------------------------------------------------------

Bugs fixed:

   * Fixed Objects not being disposed (Bug#6649
     (http://bugs.mysql.com/6649))

   * Fixed Charset-map for UCS-2 (Bug#6541 (http://bugs.mysql.com/6541))

   * Fixed Zero date "0000-00-00" is returned wrong when filling Dataset
     (Bug#6429 (http://bugs.mysql.com/6429))

   * Fixed double type handling in MySqlParameter(string parameterName,
     object value) (Bug#6428 (http://bugs.mysql.com/6428))

   * Fixed Installation directory ignored using custom installation
     (Bug#6329 (http://bugs.mysql.com/6329))

   * Fixed #HY000 Illegal mix of collations
     (latin1_swedish_ci,IMPLICIT) and (utf8_general_ (Bug#6322
     (http://bugs.mysql.com/6322))

   * Added the TableEditor CS and VB sample

   * Added charset connection string option

   * Fixed problem with MySqlBinary where string values could not be
     used to update extended text columns

   * Provider is now using character set specified by server as default

   * Updated the installer to include the new samples

   * Fixed problem where setting command text leaves the command in a
     prepared state

   * Fixed Long inserts take very long time (Bu #5453)

   * Fixed problem where calling stored procedures might cause an
     "Illegal mix of collations" problem.


File: manual.info,  Node: connector-net-news-1-0-1,  Next: connector-net-news-1-0-0,  Prev: connector-net-news-1-0-2,  Up: connector-net-news

C.3.35 Changes in MySQL Connector/NET 1.0.1 (27 October 2004)
-------------------------------------------------------------

Bugs fixed:

   * Fixed IndexOutOfBounds when reading BLOB with DataReader with
     GetString(index) (Bug#6230 (http://bugs.mysql.com/6230))

   * Fixed GetBoolean returns wrong values (Bug#6227
     (http://bugs.mysql.com/6227))

   * Fixed Method TokenizeSql() uses only a limited set of valid
     characters for parameters (Bug#6217 (http://bugs.mysql.com/6217))

   * Fixed NET Connector source missing resx files (Bug#6216
     (http://bugs.mysql.com/6216))

   * Fixed System.OverflowException when using YEAR datatype (Bug#6036
     (http://bugs.mysql.com/6036))

   * Fixed MySqlDateTime sets IsZero property on all subseq.records
     after first zero found (Bug#6006 (http://bugs.mysql.com/6006))

   * Fixed serializing of floating point parameters (double, numeric,
     single, decimal) (Bug#5900 (http://bugs.mysql.com/5900))

   * Fixed missing Reference in DbType setter (Bug#5897
     (http://bugs.mysql.com/5897))

   * Fixed Parsing the ';' char (Bug#5876 (http://bugs.mysql.com/5876))

   * Fixed DBNull Values causing problems with retrieving/updating
     queries.  (Bug#5798 (http://bugs.mysql.com/5798))

   * IsNullable error (Bug#5796 (http://bugs.mysql.com/5796))

   * Fixed problem where MySqlParameterCollection.Add() would throw
     unclear exception when given a null value (Bug#5621
     (http://bugs.mysql.com/5621))

   * Fixed construtor initialize problems in MySqlCommand() (Bug#5613
     (http://bugs.mysql.com/5613))

   * Fixed Yet Another "object reference not set to an instance of an
     object" (Bug#5496 (http://bugs.mysql.com/5496))

   * Fixed Can't display Chinese correctly (Bug#5288
     (http://bugs.mysql.com/5288))

   * Fixed MySqlDataReader and 'show tables from ...' behavior
     (Bug#5256 (http://bugs.mysql.com/5256))

   * Fixed problem in PacketReader where it could try to allocate the
     wrong buffer size in EnsureCapacity

   * Fixed problem where using old syntax while using the interfaces
     caused problems

   * Fixed Bug#5458 (http://bugs.mysql.com/5458) Calling GetChars on a
     longtext column throws an exception

   * Added test case for resetting the command text on a prepared
     command

   * Fixed Bug#5388 (http://bugs.mysql.com/5388) DataReader reports all
     rows as NULL if one row is NULL

   * Fixed problem where connection lifetime on the connect string was
     not being respected

   * Fixed Bug#5602 (http://bugs.mysql.com/5602) Possible bug in
     MySqlParameter(string, object) constructor

   * Field buffers being reused to decrease memory allocations and
     increase speed

   * Fixed Bug#5392 (http://bugs.mysql.com/5392) MySqlCommand sees "?"
     as parameters in string literals

   * Added Aggregate function test (wasn't really a bug)

   * Using PacketWriter instead of Packet for writing to streams

   * Implemented SequentialAccess

   * Fixed problem with ConnectionInternal where a key might be added
     more than once

   * Fixed Russian character support as well

   * Fixed Bug#5474 (http://bugs.mysql.com/5474) cannot run a stored
     procedure populating mysqlcommand.parameters

   * Fixed problem where connector was not issuing a CMD_QUIT before
     closing the socket

   * Fixed problem where Min Pool Size was not being respected

   * Refactored compression code into CompressedStream to clean up
     NativeDriver

   * CP1252 is now used for Latin1 only when the server is 4.1.2 and
     later

   * Fixed Bug#5469 (http://bugs.mysql.com/5469) Setting DbType throws
     NullReferenceException

   * Virtualized driver subsystem so future releases could easily
     support client or embedded server support


File: manual.info,  Node: connector-net-news-1-0-0,  Next: connector-net-0-9-0,  Prev: connector-net-news-1-0-1,  Up: connector-net-news

C.3.36 Changes in MySQL Connector/NET 1.0.0 (01 September 2004)
---------------------------------------------------------------

Bugs fixed:

   * Thai encoding not correctly supported.  (Bug#3889
     (http://bugs.mysql.com/3889))

   * Bumped version number to 1.0.0 for beta 1 release.

   * Removed all of the XML comment warnings.

   * Added `COPYING.rtf' file for use in installer.

   * Updated many of the test cases.

   * Fixed problem with using compression.

   * Removed some last references to ByteFX.


File: manual.info,  Node: connector-net-0-9-0,  Next: connector-net-news-0-76,  Prev: connector-net-news-1-0-0,  Up: connector-net-news

C.3.37 Changes in MySQL Connector/NET Version 0.9.0 (30 August 2004)
--------------------------------------------------------------------

   * Added test fixture for prepared statements.

   * All type classes now implement a `SerializeBinary' method for
     sending their data to a `PacketWriter'.

   * Added `PacketWriter' class that will enable future low-memory
     large object handling.

   * Fixed many small bugs in running prepared statements and stored
     procedures.

   * Changed command so that an exception will not be thrown in
     executing a stored procedure with parameters in old syntax mode.

   * `SingleRow' behavior now working right even with limit.

   * `GetBytes' now only works on binary columns.

   * Logger now truncates long sql commands so blob columns don't blow
     out our log.

   * host and database now have a default value of "" unless otherwise
     set.

   * Connection Timeout seems to be ignored. (Bug#5214
     (http://bugs.mysql.com/5214))

   * Added test case for bug# 5051: GetSchema not working correctly.

   * Fixed problem where `GetSchema' would return false for `IsUnique'
     when the column is key.

   * `MySqlDataReader GetXXX' methods now using the field level
     `MySqlValue' object and not performing conversions.

   * `DataReader' returning `NULL' for time column. (Bug#5097
     (http://bugs.mysql.com/5097))

   * Added test case for `LOAD DATA LOCAL INFILE'.

   * Added replacetext custom nant task.

   * Added `CommandBuilderTest' fixture.

   * Added Last One Wins feature to `CommandBuilder'.

   * Fixed persist security info case problem.

   * Fixed `GetBool' so that 1, true, "true", and "yes" all count as
     true.

   * Make parameter mark configurable.

   * Added the "old syntax" connection string parameter to allow use of
     @ parameter marker.

   * `MySqlCommandBuilder'. (Bug#4658 (http://bugs.mysql.com/4658))

   * `ByteFX.MySqlClient' caches passwords if `Persist Security Info'
     is false. (Bug#4864 (http://bugs.mysql.com/4864))

   * Updated license banner in all source files to include FLOSS
     exception.

   * Added new .Types namespace and implementations for most current
     MySql types.

   * Added `MySqlField41' as a subclass of `MySqlField'.

   * Changed many classes to now use the new .Types types.

   * Changed type `enum int' to `Int32', `short' to `Int16', and
     `bigint' to `Int64'.

   * Added dummy types `UInt16', `UInt32', and `UInt64' to allow an
     unsigned parameter to be made.

   * Connections are now reset when they are pulled from the connection
     pool.

   * Refactored auth code in driver so it can be used for both auth and
     reset.

   * Added `UserReset' test in `PoolingTests.cs'.

   * Connections are now reset using `COM_CHANGE_USER' when pulled from
     the pool.

   * Implemented `SingleResultSet' behavior.

   * Implemented support of unicode.

   * Added char set mappings for utf-8 and ucs-2.

   * Time fields overflow using bytefx .net mysql driver (Bug#4520
     (http://bugs.mysql.com/4520))

   * Modified time test in data type test fixture to check for time
     spans where hours > 24.

   * Wrong string with backslash escaping in
     `ByteFx.Data.MySqlClient.MySqlParameter'.  (Bug#4505
     (http://bugs.mysql.com/4505))

   * Added code to Parameter test case TestQuoting to test for
     backslashes.

   * `MySqlCommandBuilder' fails with multi-word column names.
     (Bug#4486 (http://bugs.mysql.com/4486))

   * Fixed bug in `TokenizeSql' where underscore would terminate
     character capture in parameter name.

   * Added test case for spaces in column names.

   * `MySqlDataReader.GetBytes' don't works correctly. (Bug#4324
     (http://bugs.mysql.com/4324))

   * Added `GetBytes()' test case to `DataReader' test fixture.

   * Now reading all server variables in `InternalConnection.Configure'
     into `Hashtable'.

   * Now using `string[]' for index map in `CharSetMap'.

   * Added CRInSQL test case for carriage returns in SQL.

   * Setting maxPacketSize to default value in `Driver.ctor'.

   * Setting `MySqlDbType' on a parameter doesn't set generic type.
     (Bug#4442 (http://bugs.mysql.com/4442))

   * Removed obsolete data types `Long' and `LongLong'.

   * Overflow exception thrown when using "use pipe" on connection
     string. (Bug#4071 (http://bugs.mysql.com/4071))

   * Changed "use pipe" keyword to "pipe name" or just "pipe".

   * Allow reading multiple resultsets from a single query.

   * Added flags attribute to `ServerStatusFlags' enum.

   * Changed name of `ServerStatus' enum to `ServerStatusFlags'.

   * Inserted data row doesn't update properly.

   * Error processing show create table. (Bug#4074
     (http://bugs.mysql.com/4074))

   * Change `Packet.ReadLenInteger' to `ReadPackedLong' and added
     `packet.ReadPackedInteger' that always reads integers packed with
     2,3,4.

   * Added `syntax.cs' test fixture to test various SQL syntax bugs.

   * Improper handling of time values. Now time value of 00:00:00 is
     not treated as null. (Bug#4149 (http://bugs.mysql.com/4149))

   * Moved all test suite files into `TestSuite' folder.

   * Fixed bug where null column would move the result packet pointer
     backward.

   * Added new nant build script.

   * Clear tablename so it will be regen'ed properly during the next
     `GenerateSchema'. (Bug#3917 (http://bugs.mysql.com/3917))

   * `GetValues' was always returning zero and was also always trying
     to copy all fields rather than respecting the size of the array
     passed in. (Bug#3915 (http://bugs.mysql.com/3915))

   * Implemented shared memory access protocol.

   * Implemented prepared statements for MySQL 4.1.

   * Implemented stored procedures for MySQL 5.0.

   * Renamed `MySqlInternalConnection' to `InternalConnection'.

   * SQL is now parsed as chars, fixes problems with other languages.

   * Added logging and allow batch connection string options.

   * `RowUpdating' event not set when setting the `DataAdapter'
     property. (Bug#3888 (http://bugs.mysql.com/3888))

   * Fixed bug in char set mapping.

   * Implemented 4.1 authentication.

   * Improved open/auth code in driver.

   * Improved how connection bits are set during connection.

   * Database name is now passed to server during initial handshake.

   * Changed namespace for client to `MySql.Data.MySqlClient'.

   * Changed assembly name of client to `MySql.Data.dll'.

   * Changed license text in all source files to GPL.

   * Added the `MySqlClient.build' Nant file.

   * Removed the mono batch files.

   * Moved some of the unused files into notused folder so nant build
     file can use wildcards.

   * Implemented shared memory access.

   * Major revamp in code structure.

   * Prepared statements now working for MySql 4.1.1 and later.

   * Finished implementing auth for 4.0, 4.1.0, and 4.1.1.

   * Changed namespace from `MySQL.Data.MySQLClient' back to
     `MySql.Data.MySqlClient'.

   * Fixed bug in `CharSetMapping' where it was trying to use text
     names as ints.

   * Changed namespace to `MySQL.Data.MySQLClient'.

   * Integrated auth changes from UC2004.

   * Fixed bug where calling any of the GetXXX methods on a datareader
     before or after reading data would not throw the appropriate
     exception (thanks Luca Morelli).

   * Added `TimeSpan' code in parameter.cs to properly serialize a
     timespan object to mysql time format (thanks Gianluca Colombo).

   * Added `TimeStamp' to parameter serialization code. Prevented
     `DataAdatper' updates from working right (thanks Michael King).

   * Fixed a misspelling in `MySqlHelper.cs' (thanks Patrick
     Kristiansen).


File: manual.info,  Node: connector-net-news-0-76,  Next: connector-net-news-0-75,  Prev: connector-net-0-9-0,  Up: connector-net-news

C.3.38 Changes in MySQL Connector/NET Version 0.76
--------------------------------------------------

   * Driver now using charset number given in handshake to create
     encoding.

   * Changed command editor to point to `MySqlClient.Design'.

   * Fixed bug in `Version.isAtLeast'.

   * Changed `DBConnectionString' to support changes done to
     `MySqlConnectionString'.

   * Removed `SqlCommandEditor' and `DataAdapterPreviewDialog'.

   * Using new long return values in many places.

   * Integrated new `CompressedStream' class.

   * Changed `ConnectionString' and added attributes to allow it to be
     used in `MySqlClient.Design'.

   * Changed `packet.cs' to support newer lengths in `ReadLenInteger'.

   * Changed other classes to use new properties and fields of
     `MySqlConnectionString'.

   * `ConnectionInternal' is now using PING to see whether the server
     is alive.

   * Moved toolbox bitmaps into resource folder.

   * Changed `field.cs' to allow values to come directly from row
     buffer.

   * Changed to use the new driver.Send syntax.

   * Using a new packet queueing system.

   * Started work handling the "broken" compression packet handling.

   * Fixed bug in `StreamCreator' where failure to connect to a host
     would continue to loop infinitly (thanks Kevin Casella).

   * Improved connectstring handling.

   * Moved designers into Pro product.

   * Removed some old commented out code from `command.cs'.

   * Fixed a problem with compression.

   * Fixed connection object where an exception throw prior to the
     connection opening would not leave the connection in the
     connecting state (thanks Chris Cline).

   * Added GUID support.

   * Fixed sequence out of order bug (thanks Mark Reay).


File: manual.info,  Node: connector-net-news-0-75,  Next: connector-net-0-74,  Prev: connector-net-news-0-76,  Up: connector-net-news

C.3.39 Changes in MySQL Connector/NET Version 0.75
--------------------------------------------------

   * Enum values now supported as parameter values (thanks Philipp
     Sumi).

   * Year datatype now supported.

   * Fixed compression.

   * Fixed bug where a parameter with a `TimeSpan' as the value would
     not serialize properly.

   * Fixed bug where default constructor would not set default
     connection string values.

   * Added some XML comments to some members.

   * Work to fix/improve compression handling.

   * Improved `ConnectionString' handling so that it better matches the
     standard set by `SqlClient'.

   * A `MySqlException' is now thrown if a username is not included in
     the connection string.

   * Localhost is now used as the default if not specified on the
     connection string.

   * An exception is now thrown if an attempt is made to set the
     connection string while the connection is open.

   * Small changes to `ConnectionString' docs.

   * Removed `MultiHostStream' and `MySqlStream'. Replaced it with
     `Common/StreamCreator'.

   * Added support for Use Pipe connection string value.

   * Added Platform class for easier access to platform utility
     functions.

   * Fixed small pooling bug where new connection was not getting
     created after `IsAlive' fails.

   * Added `Platform.cs' and `StreamCreator.cs'.

   * Fixed `Field.cs' to properly handle 4.1 style timestamps.

   * Changed `Common.Version' to `Common.DBVersion' to avoid name
     conflict.

   * Fixed `field.cs' so that text columns return the right field type.

   * Added `MySqlError' class to provide some reference for error codes
     (thanks Geert Veenstra).


File: manual.info,  Node: connector-net-0-74,  Next: connector-net-news-0-71,  Prev: connector-net-news-0-75,  Up: connector-net-news

C.3.40 Changes in MySQL Connector/NET Version 0.74
--------------------------------------------------

   * Added Unix socket support (thanks Mohammad DAMT).

   * Only calling `Thread.Sleep' when no data is available.

   * Improved escaping of quote characters in parameter data.

   * Removed misleading comments from `parameter.cs'.

   * Fixed pooling bug.

   * Fixed `ConnectionString' editor dialog (thanks marco p (pomarc)).

   * `UserId' now supported in connection strings (thanks Jeff Neeley).

   * Attempting to create a parameter that is not input throws an
     exception (thanks Ryan Gregg).

   * Added much documentation.

   * Checked in new `MultiHostStream' capability.  Big thanks to Dan
     Guisinger for this. he originally submitted the code and idea of
     supporting multiple machines on the connect string.

   * Added a lot of documentation.

   * Fixed speed issue with 0.73.

   * Changed to Thread.Sleep(0) in MySqlDataStream to help optimize the
     case where it doesn't need to wait (thanks Todd German).

   * Prepopulating the idlepools to `MinPoolSize'.

   * Fixed `MySqlPool' deadlock condition as well as stupid bug where
     CreateNewPooledConnection was not ever adding new connections to
     the pool. Also fixed `MySqlStream.ReadBytes' and `ReadByte' to not
     use `TicksPerSecond' which does not appear to always be right.
     (thanks Matthew J. Peddlesden)

   * Fix for precision and scale (thanks Matthew J. Peddlesden).

   * Added `Thread.Sleep(1)' to stream reading methods to be more cpu
     friendly (thanks Sean McGinnis).

   * Fixed problem where `ExecuteReader' would sometime return null
     (thanks Lloyd Dupont).

   * Fixed major bug with null field handling (thanks Naucki).

   * Enclosed queries for `max_allowed_packet' and `characterset'
     inside try catch (and set defaults).

   * Fixed problem where socket was not getting closed properly (thanks
     Steve!).

   * Fixed problem where `ExecuteNonQuery' was not always returning the
     right value.

   * Fixed `InternalConnection' to not use
     `@@session.max_allowed_packet' but use `@@max_allowed_packet'.
     (Thanks Miguel)

   * Added many new XML doc lines.

   * Fixed sql parsing to not send empty queries (thanks Rory).

   * Fixed problem where the reader was not unpeeking the packet on
     close.

   * Fixed problem where user variables were not being handled (thanks
     Sami Vaaraniemi).

   * Fixed loop checking in the MySqlPool (thanks Steve M. Brown)

   * Fixed `ParameterCollection.Add' method to match `SqlClient'
     (thanks Joshua Mouch).

   * Fixed `ConnectionString' parsing to handle no and yes for boolean
     and not lowercase values (thanks Naucki).

   * Added `InternalConnection' class, changes to pooling.

   * Implemented Persist Security Info.

   * Added `security.cs' and `version.cs' to project

   * Fixed `DateTime' handling in `Parameter.cs' (thanks Burkhard
     Perkens-Golomb).

   * Fixed parameter serialization where some types would throw a cast
     exception.

   * Fixed `DataReader' to convert all returned values to prevent
     casting errors (thanks Keith Murray).

   * Added code to `Command.ExecuteReader' to return null if the
     initial SQL statement throws an exception (thanks Burkhard
     Perkens-Golomb).

   * Fixed `ExecuteScalar' bug introduced with restructure.

   * Restructure to allow for `LOCAL DATA INFILE' and better sequencing
     of packets.

   * Fixed several bugs related to restructure.

   * Early work done to support more secure passwords in Mysql 4.1.
     Old passwords in 4.1 not supported yet.

   * Parameters appearing after system parameters are now handled
     correctly (Adam M. (adammil)).

   * Strings can now be assigned directly to blob fields (Adam M.).

   * Fixed float parameters (thanks Pent).

   * Improved Parameter constructor and `ParameterCollection.Add'
     methods to better match SqlClient (thanks Joshua Mouch).

   * Corrected `Connection.CreateCommand' to return a `MySqlCommand'
     type.

   * Fixed connection string designer dialog box problem (thanks
     Abraham Guyt).

   * Fixed problem with sending commands not always reading the
     response packet (thanks Joshua Mouch).

   * Fixed parameter serialization where some blobs types were not
     being handled (thanks Sean McGinnis).

   * Removed spurious `MessageBox.show' from `DataReader' code (thanks
     Joshua Mouch).

   * Fixed a nasty bug in the split sql code (thanks everyone!).


File: manual.info,  Node: connector-net-news-0-71,  Next: connector-net-news-0-70,  Prev: connector-net-0-74,  Up: connector-net-news

C.3.41 Changes in MySQL Connector/NET Version 0.71
--------------------------------------------------

   * Fixed bug in `MySqlStream' where too much data could attempt to be
     read (thanks Peter Belbin)

   * Implemented `HasRows' (thanks Nash Pherson).

   * Fixed bug where tables with more than 252 columns cause an
     exception (thanks Joshua Kessler).

   * Fixed bug where SQL statements ending in ; would cause a problem
     (thanks Shane Krueger).

   * Fixed bug in driver where error messages were getting truncated by
     1 character (thanks Shane Krueger).

   * Made `MySqlException' serializable (thanks Mathias Hasselmann).


File: manual.info,  Node: connector-net-news-0-70,  Next: connector-net-news-0-68,  Prev: connector-net-news-0-71,  Up: connector-net-news

C.3.42 Changes in MySQL Connector/NET Version 0.70
--------------------------------------------------

   * Updated some of the character code pages to be more accurate.

   * Fixed problem where readers could be opened on connections that
     had readers open.

   * Moved test to separate assembly `MySqlClientTests'.

   * Fixed stupid problem in driver with sequence out of order (Thanks
     Peter Belbin).

   * Added some pipe tests.

   * Increased default max pool size to 50.

   * Compiles with Mono 0-24.

   * Fixed connection and data reader dispose problems.

   * Added `String' datatype handling to parameter serialization.

   * Fixed sequence problem in driver that occurred after thrown
     exception (thanks Burkhard Perkens-Golomb).

   * Added support for `CommandBehavior.SingleRow' to `DataReader'.

   * Fixed command sql processing so quotes are better handled (thanks
     Theo Spears).

   * Fixed parsing of double, single, and decimal values to account for
     non-English separators. You still have to use the right syntax if
     you using hard coded sql, but if you use parameters the code will
     convert floating point types to use '.'  appropriately internal
     both into the server and out.

   * Added `MySqlStream' class to simplify timeouts and driver coding.

   * Fixed `DataReader' so that it is closed properly when the
     associated connection is closed. [thanks smishra]

   * Made client more SqlClient compliant so that DataReaders have to
     be closed before the connection can be used to run another command.

   * Improved `DBNull.Value' handling in the fields.

   * Added several unit tests.

   * Fixed `MySqlException' base class.

   * Improved driver coding

   * Fixed bug where NextResult was returning false on the last
     resultset.

   * Added more tests for MySQL.

   * Improved casting problems by equating unsigned 32bit values to
     Int64 and unsigned 16bit values to Int32, and so forth.

   * Added new constructor for `MySqlParameter' for (name, type, size,
     srccol)

   * Fixed bug in `MySqlDataReader' where it didn't check for null
     fieldlist before returning field count.

   * Started adding `MySqlClient' unit tests (added `MySqlClient/Tests'
     folder and some test cases).

   * Fixed some things in Connection String handling.

   * Moved `INIT_DB' to `MySqlPool'. I may move it again, this is in
     preparation of the conference.

   * Fixed bug inside `CommandBuilder' that prevented inserts from
     happening properly.

   * Reworked some of the internals so that all three execute methods
     of Command worked properly.

   * Fixed many small bugs found during benchmarking.

   * The first cut of `CoonectionPooling' is working. "min pool size"
     and "max pool size" are respected.

   * Work to enable multiple resultsets to be returned.

   * Character sets are handled much more intelligently now. The driver
     queries MySQL at startup for the default character set.  That
     character set is then used for conversions if that code page can
     be loaded. If not, then the default code page for the current OS
     is used.

   * Added code to save the inferred type in the name,value constructor
     of `Parameter'.

   * Also, inferred type if value of null parameter is changed using
     `Value' property.

   * Converted all files to use proper Camel case. MySQL is now MySql
     in all files. PgSQL is now PgSql.

   * Added attribute to PgSql code to prevent designer from trying to
     show.

   * Added `MySQLDbType' property to Parameter object and added proper
     conversion code to convert from `DbType' to `MySQLDbType').

   * Removed unused `ObjectToString' method from `MySQLParameter.cs'.

   * Fixed `Add(..)' method in `ParameterCollection' so that it doesn't
     use `Add(name, value)' instead.

   * Fixed `IndexOf' and `Contains' in `ParameterCollection' to be
     aware that parameter names are now stored without @.

   * Fixed `Command.ConvertSQLToBytes' so it only allows characters
     that can be in MySQL variable names.

   * Fixed `DataReader' and `Field' so that blob fields read their data
     from `Field.cs' and `GetBytes' works right.

   * Added simple query builder editor to `CommandText' property of
     `MySQLCommand'.

   * Fixed `CommandBuilder' and `Parameter' serialization to account for
     Parameters not storing @ in their names.

   * Removed `MySQLFieldType' enum from Field.cs.  Now using
     `MySQLDbType' enum.

   * Added `Designer' attribute to several classes to prevent designer
     view when using VS.Net.

   * Fixed Initial catalog typo in `ConnectionString' designer.

   * Removed 3 parameter constructor for `MySQLParameter' that
     conflicted with (name, type, value).

   * Changed `MySQLParameter' so `paramName' is now stored without
     leading @ (this fixed null inserts when using designer).

   * Changed `TypeConverter' for `MySQLParameter' to use the
     constructor with all properties.


File: manual.info,  Node: connector-net-news-0-68,  Next: connector-net-news-0-65,  Prev: connector-net-news-0-70,  Up: connector-net-news

C.3.43 Changes in MySQL Connector/NET Version 0.68
--------------------------------------------------

   * Fixed sequence issue in driver.

   * Added `DbParametersEditor' to make parameter editing more like
     `SqlClient'.

   * Fixed `Command' class so that parameters can be edited using the
     designer

   * Update connection string designer to support `Use Compression'
     flag.

   * Fixed string encoding so that European characters will work
     correctly.

   * Creating base classes to aid in building new data providers.

   * Added support for UID key in connection string.

   * Field, parameter, command now using DBNull.Value instead of null.

   * `CommandBuilder' using `DBNull.Value'.

   * `CommandBuilder' now builds insert command correctly when an
     auto_insert field is not present.

   * Field now uses typeof keyword to return `System.Types'
     (performance).


File: manual.info,  Node: connector-net-news-0-65,  Next: connector-net-news-0-60,  Prev: connector-net-news-0-68,  Up: connector-net-news

C.3.44 Changes in MySQL Connector/NET Version 0.65
--------------------------------------------------

   * `MySQLCommandBuilder' now implemented.

   * Transaction support now implemented (not all table types support
     this).

   * `GetSchemaTable' fixed to not use xsd (for Mono).

   * Driver is now Mono-compatible.

   * TIME data type now supported.

   * More work to improve Timestamp data type handling.

   * Changed signatures of all classes to match corresponding
     `SqlClient' classes.


File: manual.info,  Node: connector-net-news-0-60,  Next: connector-net-news-0-50,  Prev: connector-net-news-0-65,  Up: connector-net-news

C.3.45 Changes in MySQL Connector/NET Version 0.60
--------------------------------------------------

   * Protocol compression using SharpZipLib (www.icsharpcode.net).

   * Named pipes on Windows now working properly.

   * Work done to improve `Timestamp' data type handling.

   * Implemented `IEnumerable' on `DataReader' so `DataGrid' would work.


File: manual.info,  Node: connector-net-news-0-50,  Prev: connector-net-news-0-60,  Up: connector-net-news

C.3.46 Changes in MySQL Connector/NET Version 0.50
--------------------------------------------------

   * Speed increased dramatically by removing bugging network sync code.

   * Driver no longer buffers rows of data (more ADO.Net compliant).

   * Conversion bugs related to `TIMESTAMP' and `DATETIME' fields fixed.


File: manual.info,  Node: vstudio-plugin-news,  Next: cj-news,  Prev: connector-net-news,  Up: news

C.4 MySQL Visual Studio Plugin Change History
=============================================

* Menu:

* vstudio-plugin-news-1-0-3::    Changes in MySQL Visual Studio Plugin 1.0.3 (Not yet released)
* vstudio-plugin-news-1-0-2::    Changes in MySQL Visual Studio Plugin 1.0.2 (Not yet released)
* vstudio-plugin-news-1-0-1::    Changes in MySQL Visual Studio Plugin 1.0.1 (4 October 2006)
* vstudio-plugin-news-1-0-0::    Changes in MySQL Visual Studio Plugin 1.0.0 (4 October 2006)

*Note*:

As of Connector/NET 5.1.2 (14 June 2007), the Visual Studion Plugin is
part of the main Connector/NET package. For the change history for the
Visual Studio Plugin, see *Note connector-net-news::.


File: manual.info,  Node: vstudio-plugin-news-1-0-3,  Next: vstudio-plugin-news-1-0-2,  Prev: vstudio-plugin-news,  Up: vstudio-plugin-news

C.4.1 Changes in MySQL Visual Studio Plugin 1.0.3 (Not yet released)
--------------------------------------------------------------------

Bugs fixed:

   * Running queries based on a stored procedure would cause the data
     set designer to terminate. (Bugs #26364)

   * DataSet wizard would show all tables instead of only the tables
     available within the selected database. (Bugs #26348)


File: manual.info,  Node: vstudio-plugin-news-1-0-2,  Next: vstudio-plugin-news-1-0-1,  Prev: vstudio-plugin-news-1-0-3,  Up: vstudio-plugin-news

C.4.2 Changes in MySQL Visual Studio Plugin 1.0.2 (Not yet released)
--------------------------------------------------------------------

Bugs fixed:

   * The Add Connection dialog of the Server Explorer would freeze when
     accessing databases with capitalized characters in their name.
     (Bug#24875 (http://bugs.mysql.com/24875))

   * Creating a connection through the Server Explorer when using the
     Visual Studio Plugin would fail. The installer for the Visual
     Studio Plugin has been updated to ensure that Connector/NET 5.0.2
     must be installed.  (Bug#23071 (http://bugs.mysql.com/23071))


File: manual.info,  Node: vstudio-plugin-news-1-0-1,  Next: vstudio-plugin-news-1-0-0,  Prev: vstudio-plugin-news-1-0-2,  Up: vstudio-plugin-news

C.4.3 Changes in MySQL Visual Studio Plugin 1.0.1 (4 October 2006)
------------------------------------------------------------------

This is a bug fix release to resolve an incompatibility issue with
Connector/NET 5.0.1.

It is critical that this release only be used with Connector/NET 5.0.1.
After installing Connector/NET 5.0.1, you will need to make a small
change in your machine.config file. This file should be located at
`%win%\Microsoft.Net\Framework\v2.0.50727\CONFIG\machine.config'
(`%win%' should be the location of your Windows folder). Near the
bottom of the file you will see a line like this:

     <add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient"
     description=".Net Framework Data Provider for MySQL"
     type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data"/>

It needs to be changed to be like this:

     <add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient"
     description=".Net Framework Data Provider for MySQL"
     type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data,
     Version=5.0.1.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d"/>


File: manual.info,  Node: vstudio-plugin-news-1-0-0,  Prev: vstudio-plugin-news-1-0-1,  Up: vstudio-plugin-news

C.4.4 Changes in MySQL Visual Studio Plugin 1.0.0 (4 October 2006)
------------------------------------------------------------------

Bugs fixed:

   * Ability to work with MySQL objects (tables, views, stored
     procedures, etc) from within Server Explorer.

   * DDEX (Data Designer Extensibility) compatibility.


File: manual.info,  Node: cj-news,  Next: news-connector-mxj,  Prev: vstudio-plugin-news,  Up: news

C.5 MySQL Connector/J Change History
====================================

* Menu:

* cj-news-5-1::                  Changes in MySQL Connector/J 5.1.x
* cj-news-5-0::                  Changes in MySQL Connector/J 5.0.x
* cg-news-3-1::                  Changes in MySQL Connector/J 3.1.x
* cg-news-3-0::                  Changes in MySQL Connector/J 3.0.x
* cj-news-2-0::                  Changes in MySQL Connector/J 2.0.x
* cj-news-1-2b::                 Changes in MySQL Connector/J 1.2b (04 July 1999)
* cg-news-1-0::                  Changes in MySQL Connector/J 1.2.x and lower


File: manual.info,  Node: cj-news-5-1,  Next: cj-news-5-0,  Prev: cj-news,  Up: cj-news

C.5.1 Changes in MySQL Connector/J 5.1.x
----------------------------------------

* Menu:

* cj-news-5-1-7::                Changes in MySQL Connector/J 5.1.7 (Not yet released)
* cj-news-5-1-6::                Changes in MySQL Connector/J 5.1.6 (07 March 2008)
* cj-news-5-1-5::                Changes in MySQL Connector/J 5.1.5 (09 October 2007)
* cj-news-5-1-4::                Changes in MySQL Connector/J 5.1.4 (Not Released)
* cj-news-5-1-3::                Changes in MySQL Connector/J 5.1.3 (10 September 2007)
* cj-news-5-1-2::                Changes in MySQL Connector/J 5.1.2 (29 June 2007)
* cj-news-5-1-1::                Changes in MySQL Connector/J 5.1.1 (22 June 2007)
* cj-news-5-1-0::                Changes in MySQL Connector/J 5.1.0 (11 April 2007)


File: manual.info,  Node: cj-news-5-1-7,  Next: cj-news-5-1-6,  Prev: cj-news-5-1,  Up: cj-news-5-1

C.5.1.1 Changes in MySQL Connector/J 5.1.7 (Not yet released)
.............................................................

Bugs fixed:

   * Incorrect result is returned from `isAfterLast()' in streaming
     `ResultSet' when using `setFetchSize(Integer.MIN_VALUE)'.
     (Bug#35170 (http://bugs.mysql.com/35170))


File: manual.info,  Node: cj-news-5-1-6,  Next: cj-news-5-1-5,  Prev: cj-news-5-1-7,  Up: cj-news-5-1

C.5.1.2 Changes in MySQL Connector/J 5.1.6 (07 March 2008)
..........................................................

Functionality added or changed:

   * Multiple result sets were not supported when using streaming mode
     to return data. Both normal statements and the resul sets from
     stored procedures now return multiple results sets, with the
     exception of result sets using registered `OUTPUT' paramaters.
     (Bug#33678 (http://bugs.mysql.com/33678))

   * XAConnections and datasources have been updated to the JDBC-4.0
     standard.

   * The profiler event handling has been made extensible via the
     `profilerEventHandler' connection property.

   * Add the `verifyServerCertificate' propery. If set to "false" the
     driver will not verify the server's certificate when `useSSL' is
     set to "true"

     When using this feature, the keystore parameters should be
     specified by the `clientCertificateKeyStore*' properties, rather
     than system properties, as the JSSE doesn't it straightforward to
     have a non-verifying trust store and the "default" key store.

Bugs fixed:

   * DatabaseMetaData.getColumns() returns incorrect `COLUMN_SIZE'
     value for `SET' column.  (Bug#36830 (http://bugs.mysql.com/36830))

   * When trying to read Time values like `00:00:00' with
     ResultSet.getTime(int) an exception is thrown.  (Bug#36051
     (http://bugs.mysql.com/36051))

   * JDBC connection URL parameters is ignored when using
     `MysqlConnectionPoolDataSource'.  (Bug#35810
     (http://bugs.mysql.com/35810))

   * When `useServerPrepStmts=true' and slow query logging is enabled,
     the connector throws a NullPointerException when it encounters a
     slow query.  (Bug#35666 (http://bugs.mysql.com/35666))

   * When using the keyword `loadbalance' in the connection string and
     trying to perform load balancing between two databases, the driver
     appears to hang.  (Bug#35660 (http://bugs.mysql.com/35660))

   * JDBC data type getter method was changed to accept only column
     name, whereas previously it accepted column label.  (Bug#35610
     (http://bugs.mysql.com/35610))

   * Prepared statements from pooled connections caused a
     NullPointerException when closed() under JDBC-4.0.  (Bug#35489
     (http://bugs.mysql.com/35489))

   * In calling a stored function returning a `bigint', an exception is
     encountered beginning:

          java.sql.SQLException: java.lang.NumberFormatException: For input string:

     followed by the text of the stored function starting after the
     argument list.  (Bug#35199 (http://bugs.mysql.com/35199))

   * The JDBC driver uses a different method for evaluating column
     names in resultsetmetadata.getColumnName() and when looking for a
     column in resultset.getObject(columnName). This causes Hibernate
     to fail in queries where the two methods yield different results,
     for example in queries that use alias names:

          SELECT column AS aliasName from table

     (Bug#35150 (http://bugs.mysql.com/35150))

   * `MysqlConnectionPoolDataSource' does not support
     `ReplicationConnection'. Notice that we implemented
     `com.mysql.jdbc.Connection' for `ReplicationConnection', however,
     only accessors from ConnectionProperties are implemented (not the
     mutators), and they return values from the currently active
     connection. All other methods from `com.mysql.jdbc.Connection' are
     implemented, and operate on the currently active connection, with
     the exception of `resetServerState()' and `changeUser()'.
     (Bug#34937 (http://bugs.mysql.com/34937))

   * `ResultSet.getTimestamp()' returns incorrect values for month/day
     of `TIMESTAMP's when using server-side prepared statements (not
     enabled by default).  (Bug#34913 (http://bugs.mysql.com/34913))

   * RowDataStatic does't always set the metadata in ResultSetRow,
     which can lead to failures when unpacking `DATE', `TIME',
     `DATETIME' and `TIMESTAMP' types when using absolute, relative,
     and previous result set navigation methods.  (Bug#34762
     (http://bugs.mysql.com/34762))

   * When calling `isValid()' on an active connection, if the timeout
     is non-zero then the `Connection' is invalidated even if the
     `Connection' is valid.  (Bug#34703 (http://bugs.mysql.com/34703))

   * It was not possible to truncate a `BLOB' using `Blog.truncate()'
     when using 0 as an argument.  (Bug#34677
     (http://bugs.mysql.com/34677))

   * When using a cursor fetch for a statement, the internal prepared
     statement could cause a memory leak until the connection was
     closed. The internal prepared statement is now deleted when the
     corresponding result set is closed.  (Bug#34518
     (http://bugs.mysql.com/34518))

   * When retrieving the column type name of a geometry field, the
     driver would return `UNKNOWN' instead of `GEOMETRY'.  (Bug#34194
     (http://bugs.mysql.com/34194))

   * Statements with batched values do not return correct values for
     `getGeneratedKeys()' when `rewriteBatchedStatements' is set to
     `true', and the statement has an `ON DUPLICATE KEY UPDATE' clause.
     (Bug#34093 (http://bugs.mysql.com/34093))

   * The internal class ResultSetInternalMethods referenced the
     non-public class com.mysql.jdbc.CachedResultSetMetaData.
     (Bug#33823 (http://bugs.mysql.com/33823))

   * A `NullPointerException' could be raised when using client-side
     prepared statements and enabled the prepared statement cache using
     the `cachePrepStmts'.  (Bug#33734 (http://bugs.mysql.com/33734))

   * Using server side cursors and cursor fetch, the table metadata
     information would return the data type name instead of the column
     name.  (Bug#33594 (http://bugs.mysql.com/33594))

   * ResultSet.getTimestamp() would throw a `NullPointerException'
     instead of a `SQLException' when called on an empty `ResultSet'.
     (Bug#33162 (http://bugs.mysql.com/33162))

   * Load balancing connection using best response time would
     incorrectly "stick" to hosts that were down when the connection
     was first created.

     We solve this problem with a black list that is used during the
     picking of new hosts. If the black list ends up including all
     configured hosts, the driver will retry for a configurable number
     of times (the `retriesAllDown' configuration property, with a
     default of 120 times), sleeping 250ms between attempts to pick a
     new connection.

     We've also went ahead and made the balancing strategy extensible.
     To create a new strategy, implement the interface
     com.mysql.jdbc.BalanceStrategy (which also includes our standard
     "extension" interface), and tell the driver to use it by passing
     in the class name via the `loadBalanceStrategy' configuration
     property.  (Bug#32877 (http://bugs.mysql.com/32877))

   * During a Daylight Savings Time (DST) switchover, there was no way
     to store two timestamp/datetime values , as the hours end up being
     the same when sent as the literal that MySQL requires.

     Note that to get this scenario to work with MySQL (since it
     doesn't support per-value timezones), you need to configure your
     server (or session) to be in UTC, and tell the driver not to use
     the legacy date/time code by setting `useLegacyDatetimeCode' to
     "false". This will cause the driver to always convert to/from the
     server and client timezone consistently.

     This bug fix also fixes Bug#15604 (http://bugs.mysql.com/15604),
     by adding entirely new date/time handling code that can be
     switched on by `useLegacyDatetimeCode' being set to "false" as a
     JDBC configuration property. For Connector/J 5.1.x, the default is
     "true", in trunk and beyond it will be "false" (i.e. the old
     date/time handling code will be deprecated) (Bug#32577
     (http://bugs.mysql.com/32577), Bug#15604
     (http://bugs.mysql.com/15604))

   * When unpacking rows directly, we don't hand off error message
     packets to the internal method which decodes them correctly, so no
     exception is raised, and the driver than hangs trying to read rows
     that aren't there. This tends to happen when calling stored
     procedures, as normal SELECTs won't have an error in this spot in
     the protocol unless an I/O error occurs.  (Bug#32246
     (http://bugs.mysql.com/32246))

   * When using a connection from ConnectionPoolDataSource, some
     `Connection.prepareStatement()' methods would return null instead
     of the prepared statement.  (Bug#32101
     (http://bugs.mysql.com/32101))

   * Using `CallableStatement.setNull()' on a stored function would
     throw an `ArrayIndexOutOfBounds' exception when setting the last
     parameter to null.  (Bug#31823 (http://bugs.mysql.com/31823))

   * MysqlValidConnectionChecker doesn't properly handle connections
     created using ReplicationConnection.  (Bug#31790
     (http://bugs.mysql.com/31790))

   * Retrieving the server version information for an active connection
     could return invalid information if the default character encoding
     on the host was not ASCII compatible.  (Bug#31192
     (http://bugs.mysql.com/31192))

   * Further fixes have been made to this bug in the event that a node
     is non-responsive. Connector/J will now try a different random
     node instead of waiting for the node to recover before continuing.
     (Bug#31053 (http://bugs.mysql.com/31053))

   * `ResultSet' returned by `Statement.getGeneratedKeys()' is not
     closed automatically when statement that created it is closed.
     (Bug#30508 (http://bugs.mysql.com/30508))

   * `DatabaseMetadata.getColumns()' doesn't return the correct column
     names if the connection character isn't UTF-8. A bug in MySQL
     server compounded the issue, but was fixed within the MySQL 5.0
     release cycle. The fix includes changes to all the sections of the
     code that access the server metadata.  (Bug#20491
     (http://bugs.mysql.com/20491))

   * Fixed ResultSetMetadata.getColumnName() for result sets returned
     from Statement.getGeneratedKeys() - it was returning null instead
     of "GENERATED_KEY" as in 5.0.x.


File: manual.info,  Node: cj-news-5-1-5,  Next: cj-news-5-1-4,  Prev: cj-news-5-1-6,  Up: cj-news-5-1

C.5.1.3 Changes in MySQL Connector/J 5.1.5 (09 October 2007)
............................................................

The following     features are new, compared to the 5.0 series of
Connector/J

   * Support for JDBC-4.0 `NCHAR', `NVARCHAR' and `NCLOB' types.

   * JDBC-4.0 support for setting per-connection client information
     (which can be viewed in the comments section of a query via `SHOW
     PROCESSLIST' on a MySQL server, or can be extended to support
     custom persistence of the information via a public interface).

   * Support for JDBC-4.0 XML processing via JAXP interfaces to DOM,
     SAX and StAX.

   * JDBC-4.0 standardized unwrapping to interfaces that include vendor
     extensions.

Functionality added or changed:

   * Added `autoSlowLog' configuration property, overrides
     `slowQueryThreshold*' properties, driver determines slow queries
     by those that are slower than 5 * stddev of the mean query time
     (outside the 96% percentile).

Bugs fixed:

   * When a connection is in read-only mode, queries that are wrapped
     in parentheses were incorrectly identified DML statements.
     (Bug#28256 (http://bugs.mysql.com/28256))


File: manual.info,  Node: cj-news-5-1-4,  Next: cj-news-5-1-3,  Prev: cj-news-5-1-5,  Up: cj-news-5-1

C.5.1.4 Changes in MySQL Connector/J 5.1.4 (Not Released)
.........................................................

Only released internally.


File: manual.info,  Node: cj-news-5-1-3,  Next: cj-news-5-1-2,  Prev: cj-news-5-1-4,  Up: cj-news-5-1

C.5.1.5 Changes in MySQL Connector/J 5.1.3 (10 September 2007)
..............................................................

The following     features are new, compared to the 5.0 series of
Connector/J

   * Support for JDBC-4.0 `NCHAR', `NVARCHAR' and `NCLOB' types.

   * JDBC-4.0 support for setting per-connection client information
     (which can be viewed in the comments section of a query via `SHOW
     PROCESSLIST' on a MySQL server, or can be extended to support
     custom persistence of the information via a public interface).

   * Support for JDBC-4.0 XML processing via JAXP interfaces to DOM,
     SAX and StAX.

   * JDBC-4.0 standardized unwrapping to interfaces that include vendor
     extensions.

Functionality added or changed:

   * Connector/J now connects using an initial character set of `utf-8'
     solely for the purpose of authentication to allow user names or
     database names in any character set to be used in the JDBC
     connection URL.  (Bug#29853 (http://bugs.mysql.com/29853))

   * Added two configuration parameters:

        * `blobsAreStrings' -- Should the driver always treat BLOBs as
          Strings. Added specifically to work around dubious metadata
          returned by the server for `GROUP BY' clauses. Defaults to
          false.

        * `functionsNeverReturnBlobs' -- Should the driver always treat
          data from functions returning `BLOBs' as Strings. Added
          specifically to work around dubious metadata returned by the
          server for `GROUP BY' clauses. Defaults to false.

   * Setting `rewriteBatchedStatements' to `true' now causes
     CallableStatements with batched arguments to be re-written in the
     form "CALL (...); CALL (...); ..." to send the batch in as few
     client-server round trips as possible.

   * The driver now picks appropriate internal row representation
     (whole row in one buffer, or individual byte[]s for each column
     value) depending on heuristics, including whether or not the row
     has `BLOB' or `TEXT' types and the overall row-size. The threshold
     for row size that will cause the driver to use a buffer rather
     than individual byte[]s is configured by the configuration property
     `largeRowSizeThreshold', which has a default value of 2KB.

   * The data (and how it's stored) for `ResultSet' rows are now behind
     an interface which allows us (in some cases) to allocate less
     memory per row, in that for "streaming" result sets, we re-use the
     packet used to read rows, since only one row at a time is ever
     active.

   * Added experimental support for statement "interceptors" via the
     `com.mysql.jdbc.StatementInterceptor' interface, examples are in
     `com/mysql/jdbc/interceptors'. Implement this interface to be
     placed "in between" query execution, so that it can be influenced
     (currently experimental).

   * The driver will automatically adjust the server session variable
     `net_write_timeout' when it determines its been asked for a
     "streaming" result, and resets it to the previous value when the
     result set has been consumed. (The configuration property is named
     `netTimeoutForStreamingResults', with a unit of seconds, the value
     '0' means the driver will not try and adjust this value).

   * JDBC-4.0 ease-of-development features including auto-registration
     with the `DriverManager' via the service provider mechanism,
     standardized Connection validity checks and categorized
     `SQLExceptions' based on recoverability/retry-ability and class of
     the underlying error.

   * `Statement.setQueryTimeout()'s now affect the entire batch for
     batched statements, rather than the individual statements that
     make up the batch.

   * Errors encountered during
     `Statement'/`PreparedStatement'/`CallableStatement.executeBatch()'
     when `rewriteBatchStatements' has been set to `true' now return
     `BatchUpdateExceptions' according to the setting of
     `continueBatchOnError'.

     If `continueBatchOnError' is set to `true', the update counts for
     the "chunk" that were sent as one unit will all be set to
     `EXECUTE_FAILED', but the driver will attempt to process the
     remainder of the batch. You can determine which "chunk" failed by
     looking at the update counts returned in the
     `BatchUpdateException'.

     If `continueBatchOnError' is set to "false", the update counts
     returned will contain all updates up-to and including the failed
     "chunk", with all counts for the failed "chunk" set to
     `EXECUTE_FAILED'.

     Since MySQL doesn't return multiple error codes for
     multiple-statements, or for multi-value `INSERT'/`REPLACE', it is
     the application's responsibility to handle determining which
     item(s) in the "chunk" actually failed.

   * New methods on com.mysql.jdbc.Statement:
     `setLocalInfileInputStream()' and `getLocalInfileInputStream()':

        * `setLocalInfileInputStream()' sets an `InputStream' instance
          that will be used to send data to the MySQL server for a
          `LOAD DATA LOCAL INFILE' statement rather than a
          `FileInputStream' or `URLInputStream' that represents the path
          given as an argument to the statement.

          This stream will be read to completion upon execution of a
          `LOAD DATA LOCAL INFILE' statement, and will automatically be
          closed by the driver, so it needs to be reset before each
          call to `execute*()' that would cause the MySQL server to
          request data to fulfill the request for `LOAD DATA LOCAL
          INFILE'.

          If this value is set to `NULL', the driver will revert to
          using a `FileInputStream' or `URLInputStream' as required.

        * `getLocalInfileInputStream()' returns the `InputStream'
          instance that will be used to send data in response to a
          `LOAD DATA LOCAL INFILE' statement.

          This method returns `NULL' if no such stream has been set via
          `setLocalInfileInputStream()'.

   * Setting `useBlobToStoreUTF8OutsideBMP' to `true' tells the driver
     to treat `[MEDIUM/LONG]BLOB' columns as `[LONG]VARCHAR' columns
     holding text encoded in UTF-8 that has characters outside the BMP
     (4-byte encodings), which MySQL server can't handle natively.

     Set `utf8OutsideBmpExcludedColumnNamePattern' to a regex so that
     column names matching the given regex will still be treated as
     `BLOBs' The regex must follow the patterns used for the
     `java.util.regex'package.  The default is to exclude no columns,
     and include all columns.

     Set `utf8OutsideBmpIncludedColumnNamePattern' to specify exclusion
     rules to utf8OutsideBmpExcludedColumnNamePattern". The regex must
     follow the patterns used for the `java.util.regex' package.

Bugs fixed:

   * `setObject(int, Object, int, int)' delegate in
     PreparedStatmentWrapper delegates to wrong method.  (Bug#30892
     (http://bugs.mysql.com/30892))

   * NPE with null column values when `padCharsWithSpace' is set to
     true.  (Bug#30851 (http://bugs.mysql.com/30851))

   * Collation on `VARBINARY' column types would be misidentified. A
     fix has been added, but this fix only works for MySQL server
     versions 5.0.25 and newer, since earlier versions didn't
     consistently return correct metadata for functions, and thus
     results from subqueries and functions were indistinguishable from
     each other, leading to type-related bugs.  (Bug#30664
     (http://bugs.mysql.com/30664))

   * An `ArithmeticException' or `NullPointerException' would be raised
     when the batch had zero members and
     `rewriteBatchedStatements=true' when `addBatch()' was never
     called, or `executeBatch()' was called immediately after
     `clearBatch()'.  (Bug#30550 (http://bugs.mysql.com/30550))

   * Closing a load-balanced connection would cause a
     `ClassCastException'.  (Bug#29852 (http://bugs.mysql.com/29852))

   * Connection checker for JBoss didn't use same method parameters via
     reflection, causing connections to always seem "bad".  (Bug#29106
     (http://bugs.mysql.com/29106))

   * `DatabaseMetaData.getTypeInfo()' for the types `DECIMAL' and
     `NUMERIC' will return a precision of 254 for server versions older
     than 5.0.3, 64 for versions 5.0.3-5.0.5 and 65 for versions newer
     than 5.0.5.  (Bug#28972 (http://bugs.mysql.com/28972))

   * `CallableStatement.executeBatch()' doesn't work when connection
     property `noAccessToProcedureBodies' has been set to `true'.

     The fix involves changing the behavior of
     `noAccessToProcedureBodies',in that the driver will now report all
     paramters as "IN" paramters but allow callers to call
     registerOutParameter() on them without throwing an exception.
     (Bug#28689 (http://bugs.mysql.com/28689))

   * `DatabaseMetaData.getColumns()' doesn't contain `SCOPE_*' or
     `IS_AUTOINCREMENT' columns.  (Bug#27915
     (http://bugs.mysql.com/27915))

   * Schema objects with identifiers other than the connection
     character aren't retrieved correctly in `ResultSetMetadata'.
     (Bug#27867 (http://bugs.mysql.com/27867))

   * `Connection.getServerCharacterEncoding()' doesn't work for servers
     with version >= 4.1.  (Bug#27182 (http://bugs.mysql.com/27182))

   * The automated SVN revisions in `DBMD.getDriverVersion()'. The SVN
     revision of the directory is now inserted into the version
     information during the build.  (Bug#21116
     (http://bugs.mysql.com/21116))

   * Specifying a "validation query" in your connection pool that
     starts with "/* ping */" _exactly_ will cause the driver to
     instead send a ping to the server and return a fake result set
     (much lighter weight), and when using a ReplicationConnection or a
     LoadBalancedConnection, will send the ping across all active
     connections.


File: manual.info,  Node: cj-news-5-1-2,  Next: cj-news-5-1-1,  Prev: cj-news-5-1-3,  Up: cj-news-5-1

C.5.1.6 Changes in MySQL Connector/J 5.1.2 (29 June 2007)
.........................................................

This is a new Beta development release, fixing recently discovered bugs.

Functionality added or changed:

   * Setting the configuration property `rewriteBatchedStatements' to
     `true' will now cause the driver to rewrite batched prepared
     statements with more than 3 parameter sets in a batch into
     multi-statements (separated by ";") if they are not plain (that
     is, without `SELECT' or `ON DUPLICATE KEY UPDATE' clauses)
     `INSERT' or `REPLACE' statements.


File: manual.info,  Node: cj-news-5-1-1,  Next: cj-news-5-1-0,  Prev: cj-news-5-1-2,  Up: cj-news-5-1

C.5.1.7 Changes in MySQL Connector/J 5.1.1 (22 June 2007)
.........................................................

This is a new Alpha development release, adding new features and fixing
recently discovered bugs.

Functionality added or changed:

   * *Incompatible Change*: Pulled vendor-extension methods of
     `Connection' implementation out into an interface to support
     `java.sql.Wrapper' functionality from `ConnectionPoolDataSource'.
     The vendor extensions are javadoc'd in the
     `com.mysql.jdbc.Connection' interface.

     For those looking further into the driver implementation, it is
     not an API that is used for plugability of implementations inside
     our driver (which is why there are still references to
     `ConnectionImpl' throughout the code).

     We've also added server and client `prepareStatement()' methods
     that cover all of the variants in the JDBC API.

     `Connection.serverPrepare(String)' has been re-named to
     `Connection.serverPrepareStatement()' for consistency with
     `Connection.clientPrepareStatement()'.

   * Row navigation now causes any streams/readers open on the result
     set to be closed, as in some cases we're reading directly from a
     shared network packet and it will be overwritten by the "next" row.

   * Made it possible to retrieve prepared statement parameter bindings
     (to be used in `StatementInterceptors', primarily).

   * Externalized the descriptions of connection properties.

   * The data (and how it's stored) for `ResultSet' rows are now behind
     an interface which allows us (in some cases) to allocate less
     memory per row, in that for "streaming" result sets, we re-use the
     packet used to read rows, since only one row at a time is ever
     active.

   * Similar to `Connection', we pulled out vendor extensions to
     `Statement' into an interface named `com.mysql.Statement', and
     moved the `Statement' class into `com.mysql.StatementImpl'. The
     two methods (javadoc'd in `com.mysql.Statement' are
     `enableStreamingResults()', which already existed, and
     `disableStreamingResults()' which sets the statement instance back
     to the fetch size and result set type it had before
     `enableStreamingResults()' was called.

   * Driver now picks appropriate internal row representation (whole
     row in one buffer, or individual byte[]s for each column value)
     depending on heuristics, including whether or not the row has
     `BLOB' or `TEXT' types and the overall row-size. The threshold for
     row size that will cause the driver to use a buffer rather than
     individual byte[]s is configured by the configuration property
     `largeRowSizeThreshold', which has a default value of 2KB.

   * Added experimental support for statement "interceptors" via the
     `com.mysql.jdbc.StatementInterceptor' interface, examples are in
     `com/mysql/jdbc/interceptors'.

     Implement this interface to be placed "in between" query
     execution, so that you can influence it. (currently experimental).

     `StatementInterceptors' are "chainable" when configured by the
     user, the results returned by the "current" interceptor will be
     passed on to the next on in the chain, from left-to-right order, as
     specified by the user in the JDBC configuration property
     `statementInterceptors'.

   * See the sources (fully javadoc'd) for
     `com.mysql.jdbc.StatementInterceptor' for more details until we
     iron out the API and get it documented in the manual.

   * Setting `rewriteBatchedStatements' to `true' now causes
     `CallableStatements' with batched arguments to be re-written in
     the form `CALL (...); CALL (...); ...' to send the batch in as few
     client-server round trips as possible.


File: manual.info,  Node: cj-news-5-1-0,  Prev: cj-news-5-1-1,  Up: cj-news-5-1

C.5.1.8 Changes in MySQL Connector/J 5.1.0 (11 April 2007)
..........................................................

This is the first public alpha release of the current Connector/J 5.1
development branch, providing an insight to upcoming features. Although
some of these are still under development, this release includes the
following new features and changes (in comparison to the current
Connector/J 5.0 production release):

*Important change:* Due to a number of issues with the use of
server-side prepared statements, Connector/J 5.0.5 has disabled their
use by default.  The disabling of server-side prepared statements does
not affect the operation of the connector in any way.

To enable server-side prepared statements you must add the following
configuration property to your connector string:

     useServerPrepStmts=true

The default value of this property is `false' (that is, Connector/J
does not use server-side prepared statements).

*Note*:

The disabling of server-side prepared statements does not affect the
operation of the connector. However, if you use the `useTimezone=true'
connection option and use client-side prepared statements (instead of
server-side prepared statements) you should also set
`useSSPSCompatibleTimezoneShift=true'.

Functionality added or changed:

   * Refactored `CommunicationsException' into a JDBC-3.0 version, and
     a JDBC-4.0 version (which extends `SQLRecoverableException', now
     that it exists).

     *Note*:

     This change means that if you were catching
     `com.mysql.jdbc.CommunicationsException' in your applications
     instead of looking at the SQLState class of `08', and are moving
     to Java 6 (or newer), you need to change your imports to that
     exception to be
     `com.mysql.jdbc.exceptions.jdbc4.CommunicationsException', as the
     old class will not be instantiated for communications link-related
     errors under Java 6.

   * Added support for JDBC-4.0 categorized `SQLExceptions'.

   * Added support for JDBC-4.0's `NCLOB', and `NCHAR'/`NVARCHAR' types.

   * `com.mysql.jdbc.java6.javac' -- full path to your Java-6 `javac'
     executable

   * Added support for JDBC-4.0's SQLXML interfaces.

   * Re-worked Ant buildfile to build JDBC-4.0 classes separately, as
     well as support building under Eclipse (since Eclipse can't
     mix/match JDKs).

     To build, you must set `JAVA_HOME' to J2SDK-1.4.2 or Java-5, and
     set the following properties on your Ant command line:

        * `com.mysql.jdbc.java6.javac' -- full path to your Java-6
          `javac' executable

        * `com.mysql.jdbc.java6.rtjar' -- full path to your Java-6
          `rt.jar' file

   * New feature -- driver will automatically adjust session variable
     `net_write_timeout' when it determines it has been asked for a
     "streaming" result, and resets it to the previous value when the
     result set has been consumed.  (configuration property is named
     `netTimeoutForStreamingResults' value and has a unit of seconds,
     the value `0' means the driver will not try and adjust this value).

   * Added support for JDBC-4.0's client information. The backend
     storage of information provided via `Connection.setClientInfo()'
     and retrieved by `Connection.getClientInfo()' is pluggable by any
     class that implements the `com.mysql.jdbc.JDBC4ClientInfoProvider'
     interface and has a no-args constructor.

     The implementation used by the driver is configured using the
     `clientInfoProvider' configuration property (with a default of
     value of `com.mysql.jdbc.JDBC4CommentClientInfoProvider', an
     implementation which lists the client information as a comment
     prepended to every query sent to the server).

     This functionality is only available when using Java-6 or newer.

   * `com.mysql.jdbc.java6.rtjar' -- full path to your Java-6 `rt.jar'
     file

   * Added support for JDBC-4.0's `Wrapper' interface.


File: manual.info,  Node: cj-news-5-0,  Next: cg-news-3-1,  Prev: cj-news-5-1,  Up: cj-news

C.5.2 Changes in MySQL Connector/J 5.0.x
----------------------------------------

* Menu:

* cj-news-5-0-8::                Changes in MySQL Connector/J 5.0.8 (09 October 2007)
* cj-news-5-0-7::                Changes in MySQL Connector/J 5.0.7 (20 July 2007)
* cj-news-5-0-6::                Changes in MySQL Connector/J 5.0.6 (15 May 2007)
* cj-news-5-0-5::                Changes in MySQL Connector/J 5.0.5 (02 March 2007)
* cj-news-5-0-4::                Changes in MySQL Connector/J 5.0.4 (20 October 2006)
* cj-news-5-0-3::                Changes in MySQL Connector/J 5.0.3 (26 July 2006)
* cj-news-5-0-2::                Changes in MySQL Connector/J 5.0.2 (11 July 2006)
* cj-news-5-0-1::                Changes in MySQL Connector/J 5.0.1 (Not Released)
* cj-news-5-0-0::                Changes in MySQL Connector/J 5.0.0 (22 December 2005)


File: manual.info,  Node: cj-news-5-0-8,  Next: cj-news-5-0-7,  Prev: cj-news-5-0,  Up: cj-news-5-0

C.5.2.1 Changes in MySQL Connector/J 5.0.8 (09 October 2007)
............................................................

Functionality added or changed:

   * `blobsAreStrings' -- Should the driver always treat BLOBs as
     Strings. Added specifically to work around dubious metadata
     returned by the server for `GROUP BY' clauses. Defaults to false.

   * Added two configuration parameters:

        * `blobsAreStrings' -- Should the driver always treat BLOBs as
          Strings. Added specifically to work around dubious metadata
          returned by the server for `GROUP BY' clauses. Defaults to
          false.

        * `functionsNeverReturnBlobs' -- Should the driver always treat
          data from functions returning `BLOBs' as Strings. Added
          specifically to work around dubious metadata returned by the
          server for `GROUP BY' clauses. Defaults to false.

   * `functionsNeverReturnBlobs' -- Should the driver always treat data
     from functions returning `BLOBs' as Strings. Added specifically to
     work around dubious metadata returned by the server for `GROUP BY'
     clauses. Defaults to false.

   * XAConnections now start in auto-commit mode (as per JDBC-4.0
     specification clarification).

   * Driver will now fall back to sane defaults for
     `max_allowed_packet' and `net_buffer_length' if the server reports
     them incorrectly (and will log this situation at `WARN' level,
     since it's actually an error condition).

Bugs fixed:

   * Connections established using URLs of the form
     `jdbc:mysql:loadbalance://' weren't doing failover if they tried
     to connect to a MySQL server that was down. The driver now
     attempts connections to the next "best" (depending on the load
     balance strategy in use) server, and continues to attempt
     connecting to the next "best" server every 250 milliseconds until
     one is found that is up and running or 5 minutes has passed.

     If the driver gives up, it will throw the last-received
     `SQLException'.  (Bug#31053 (http://bugs.mysql.com/31053))

   * `setObject(int, Object, int, int)' delegate in
     PreparedStatmentWrapper delegates to wrong method.  (Bug#30892
     (http://bugs.mysql.com/30892))

   * NPE with null column values when `padCharsWithSpace' is set to
     true.  (Bug#30851 (http://bugs.mysql.com/30851))

   * Collation on `VARBINARY' column types would be misidentified. A
     fix has been added, but this fix only works for MySQL server
     versions 5.0.25 and newer, since earlier versions didn't
     consistently return correct metadata for functions, and thus
     results from subqueries and functions were indistinguishable from
     each other, leading to type-related bugs.  (Bug#30664
     (http://bugs.mysql.com/30664))

   * An `ArithmeticException' or `NullPointerException' would be raised
     when the batch had zero members and
     `rewriteBatchedStatements=true' when `addBatch()' was never
     called, or `executeBatch()' was called immediately after
     `clearBatch()'.  (Bug#30550 (http://bugs.mysql.com/30550))

   * Closing a load-balanced connection would cause a
     `ClassCastException'.  (Bug#29852 (http://bugs.mysql.com/29852))

   * Connection checker for JBoss didn't use same method parameters via
     reflection, causing connections to always seem "bad".  (Bug#29106
     (http://bugs.mysql.com/29106))

   * `DatabaseMetaData.getTypeInfo()' for the types `DECIMAL' and
     `NUMERIC' will return a precision of 254 for server versions older
     than 5.0.3, 64 for versions 5.0.3-5.0.5 and 65 for versions newer
     than 5.0.5.  (Bug#28972 (http://bugs.mysql.com/28972))

   * `CallableStatement.executeBatch()' doesn't work when connection
     property `noAccessToProcedureBodies' has been set to `true'.

     The fix involves changing the behavior of
     `noAccessToProcedureBodies',in that the driver will now report all
     paramters as "IN" paramters but allow callers to call
     registerOutParameter() on them without throwing an exception.
     (Bug#28689 (http://bugs.mysql.com/28689))

   * When a connection is in read-only mode, queries that are wrapped
     in parentheses were incorrectly identified DML statements.
     (Bug#28256 (http://bugs.mysql.com/28256))

   * `UNSIGNED' types not reported via `DBMD.getTypeInfo()', and
     capitalization of type names is not consistent between
     `DBMD.getColumns()', `RSMD.getColumnTypeName()' and
     `DBMD.getTypeInfo()'.

     This fix also ensures that the precision of `UNSIGNED MEDIUMINT'
     and `UNSIGNED BIGINT' is reported correctly via
     `DBMD.getColumns()'.  (Bug#27916 (http://bugs.mysql.com/27916))

   * `DatabaseMetaData.getColumns()' doesn't contain `SCOPE_*' or
     `IS_AUTOINCREMENT' columns.  (Bug#27915
     (http://bugs.mysql.com/27915))

   * Schema objects with identifiers other than the connection
     character aren't retrieved correctly in `ResultSetMetadata'.
     (Bug#27867 (http://bugs.mysql.com/27867))

   * Cached metadata with `PreparedStatement.execute()' throws
     `NullPointerException'.  (Bug#27412 (http://bugs.mysql.com/27412))

   * `Connection.getServerCharacterEncoding()' doesn't work for servers
     with version >= 4.1.  (Bug#27182 (http://bugs.mysql.com/27182))

   * The automated SVN revisions in `DBMD.getDriverVersion()'. The SVN
     revision of the directory is now inserted into the version
     information during the build.  (Bug#21116
     (http://bugs.mysql.com/21116))

   * Specifying a "validation query" in your connection pool that
     starts with "/* ping */" _exactly_ will cause the driver to
     instead send a ping to the server and return a fake result set
     (much lighter weight), and when using a ReplicationConnection or a
     LoadBalancedConnection, will send the ping across all active
     connections.


File: manual.info,  Node: cj-news-5-0-7,  Next: cj-news-5-0-6,  Prev: cj-news-5-0-8,  Up: cj-news-5-0

C.5.2.2 Changes in MySQL Connector/J 5.0.7 (20 July 2007)
.........................................................

Functionality added or changed:

   * The driver will now automatically set `useServerPrepStmts' to
     `true' when `useCursorFetch' has been set to `true', since the
     feature requires server-side prepared statements in order to
     function.

   * `tcpKeepAlive' - Should the driver set SO_KEEPALIVE (default
     `true')?

   * Give more information in EOFExceptions thrown out of MysqlIO (how
     many bytes the driver expected to read, how many it actually read,
     say that communications with the server were unexpectedly lost).

   * Driver detects when it is running in a ColdFusion MX server
     (tested with version 7), and uses the configuration bundle
     `coldFusion', which sets `useDynamicCharsetInfo' to `false' (see
     previous entry), and sets `useLocalSessionState' and autoReconnect
     to `true'.

   * `tcpNoDelay' - Should the driver set SO_TCP_NODELAY (disabling the
     Nagle Algorithm, default `true')?

   * Added configuration property `slowQueryThresholdNanos' - if
     `useNanosForElapsedTime' is set to `true', and this property is
     set to a non-zero value the driver will use this threshold (in
     nanosecond units) to determine if a query was slow, instead of
     using millisecond units.

   * `tcpRcvBuf' - Should the driver set SO_RCV_BUF to the given value?
     The default value of '0', means use the platform default value for
     this property.

   * Setting `useDynamicCharsetInfo' to `false' now causes driver to
     use static lookups for collations as well (makes
     ResultSetMetadata.isCaseSensitive() much more efficient, which
     leads to performance increase for ColdFusion, which calls this
     method for every column on every table it sees, it appears).

   * Added configuration properties to allow tuning of TCP/IP socket
     parameters:

        * `tcpNoDelay' - Should the driver set SO_TCP_NODELAY
          (disabling the Nagle Algorithm, default `true')?

        * `tcpKeepAlive' - Should the driver set SO_KEEPALIVE (default
          `true')?

        * `tcpRcvBuf' - Should the driver set SO_RCV_BUF to the given
          value? The default value of '0', means use the platform
          default value for this property.

        * `tcpSndBuf' - Should the driver set SO_SND_BUF to the given
          value? The default value of '0', means use the platform
          default value for this property.

        * `tcpTrafficClass' - Should the driver set traffic class or
          type-of-service fields? See the documentation for
          java.net.Socket.setTrafficClass() for more information.

   * Setting the configuration parameter `useCursorFetch' to `true' for
     MySQL-5.0+ enables the use of cursors that allow Connector/J to
     save memory by fetching result set rows in chunks (where the chunk
     size is set by calling setFetchSize() on a Statement or ResultSet)
     by using fully-materialized cursors on the server.

   * `tcpSndBuf' - Should the driver set SO_SND_BUF to the given value?
     The default value of '0', means use the platform default value for
     this property.

   * `tcpTrafficClass' - Should the driver set traffic class or
     type-of-service fields? See the documentation for
     java.net.Socket.setTrafficClass() for more information.

   * Added new debugging functionality - Setting configuration property
     `includeInnodbStatusInDeadlockExceptions' to `true' will cause the
     driver to append the output of `SHOW ENGINE INNODB STATUS' to
     deadlock-related exceptions, which will enumerate the current
     locks held inside InnoDB.

   * Added configuration property `useNanosForElapsedTime' - for
     profiling/debugging functionality that measures elapsed time,
     should the driver try to use nanoseconds resolution if available
     (requires JDK >= 1.5)?

     *Note*:

     If `useNanosForElapsedTime' is set to `true', and this property is
     set to "0" (or left default), then elapsed times will still be
     measured in nanoseconds (if possible), but the slow query
     threshold will be converted from milliseconds to nanoseconds, and
     thus have an upper bound of approximately 2000 milliseconds (as
     that threshold is represented as an integer, not a long).

Bugs fixed:

   * Don't send any file data in response to LOAD DATA LOCAL INFILE if
     the feature is disabled at the client side. This is to prevent a
     malicious server or man-in-the-middle from asking the client for
     data that the client is not expecting. Thanks to Jan Kneschke for
     discovering the exploit and Andrey "Poohie" Hristov, Konstantin
     Osipov and Sergei Golubchik for discussions about implications and
     possible fixes.  (Bug#29605 (http://bugs.mysql.com/29605))

   * Parser in client-side prepared statements runs to end of
     statement, rather than end-of-line for '#' comments. Also added
     support for '-' single-line comments.  (Bug#28956
     (http://bugs.mysql.com/28956))

   * Parser in client-side prepared statements eats character following
     '/' if it's not a multi-line comment.  (Bug#28851
     (http://bugs.mysql.com/28851))

   * PreparedStatement.getMetaData() for statements containing leading
     one-line comments is not returned correctly.

     As part of this fix, we also overhauled detection of DML for
     `executeQuery()' and `SELECT's for `executeUpdate()' in plain and
     prepared statements to be aware of the same types of comments.
     (Bug#28469 (http://bugs.mysql.com/28469))


File: manual.info,  Node: cj-news-5-0-6,  Next: cj-news-5-0-5,  Prev: cj-news-5-0-7,  Up: cj-news-5-0

C.5.2.3 Changes in MySQL Connector/J 5.0.6 (15 May 2007)
........................................................

Functionality added or changed:

   * Added an experimental load-balanced connection designed for use
     with SQL nodes in a MySQL Cluster/NDB environment (This is not for
     master-slave replication. For that, we suggest you look at
     `ReplicationConnection' or `lbpool').

     If the JDBC URL starts with
     `jdbc:mysql:loadbalance://host-1,host-2,...host-n', the driver
     will create an implementation of `java.sql.Connection' that load
     balances requests across a series of MySQL JDBC connections to the
     given hosts, where the balancing takes place after transaction
     commit.

     Therefore, for this to work (at all), you must use transactions,
     even if only reading data.

     Physical connections to the given hosts will not be created until
     needed.

     The driver will invalidate connections that it detects have had
     communication errors when processing a request. A new connection
     to the problematic host will be attempted the next time it is
     selected by the load balancing algorithm.

     There are two choices for load balancing algorithms, which may be
     specified by the `loadBalanceStrategy' JDBC URL configuration
     property:

        * `random' -- the driver will pick a random host for each
          request. This tends to work better than round-robin, as the
          randomness will somewhat account for spreading loads where
          requests vary in response time, while round-robin can
          sometimes lead to overloaded nodes if there are variations in
          response times across the workload.

        * `bestResponseTime' -- the driver will route the request to
          the host that had the best response time for the previous
          transaction.

   * `bestResponseTime' -- the driver will route the request to the
     host that had the best response time for the previous transaction.

   * Added configuration property `padCharsWithSpace' (defaults to
     `false'). If set to `true', and a result set column has the `CHAR'
     type and the value does not fill the amount of characters
     specified in the DDL for the column, the driver will pad the
     remaining characters with space (for ANSI compliance).

   * When `useLocalSessionState' is set to `true' and connected to a
     MySQL-5.0 or later server, the JDBC driver will now determine
     whether an actual `commit' or `rollback' statement needs to be
     sent to the database when `Connection.commit()' or
     `Connection.rollback()' is called.

     This is especially helpful for high-load situations with
     connection pools that always call `Connection.rollback()' on
     connection check-in/check-out because it avoids a round-trip to
     the server.

   * Added configuration property `useDynamicCharsetInfo'. If set to
     `false' (the default), the driver will use a per-connection cache
     of character set information queried from the server when
     necessary, or when set to `true', use a built-in static mapping
     that is more efficient, but isn't aware of custom character sets or
     character sets implemented after the release of the JDBC driver.

     *Note*:

     This only affects the `padCharsWithSpace' configuration property
     and the `ResultSetMetaData.getColumnDisplayWidth()' method.

   * New configuration property, `enableQueryTimeouts' (default `true').

     When enabled, query timeouts set via `Statement.setQueryTimeout()'
     use a shared `java.util.Timer' instance for scheduling. Even if
     the timeout doesn't expire before the query is processed, there
     will be memory used by the `TimerTask' for the given timeout which
     won't be reclaimed until the time the timeout would have expired
     if it hadn't been cancelled by the driver. High-load environments
     might want to consider disabling this functionality. (this
     configuration property is part of the `maxPerformance'
     configuration bundle).

   * Give better error message when "streaming" result sets, and the
     connection gets clobbered because of exceeding `net_write_timeout'
     on the server.

   * `random' -- the driver will pick a random host for each request.
     This tends to work better than round-robin, as the randomness will
     somewhat account for spreading loads where requests vary in
     response time, while round-robin can sometimes lead to overloaded
     nodes if there are variations in response times across the
     workload.

   * `com.mysql.jdbc.[NonRegistering]Driver' now understands URLs of
     the format `jdbc:mysql:replication://' and
     `jdbc:mysql:loadbalance://' which will create a
     ReplicationConnection (exactly like when using
     `[NonRegistering]ReplicationDriver') and an experimental
     load-balanced connection designed for use with SQL nodes in a
     MySQL Cluster/NDB environment, respectively.

     In an effort to simplify things, we're working on deprecating
     multiple drivers, and instead specifying different core behavior
     based upon JDBC URL prefixes, so watch for
     `[NonRegistering]ReplicationDriver' to eventually disappear, to be
     replaced with `com.mysql.jdbc[NonRegistering]Driver' with the new
     URL prefix.

   * Fixed issue where a failed-over connection would let an
     application call `setReadOnly(false)', when that call should be
     ignored until the connection is reconnected to a writable master
     unless `failoverReadOnly' had been set to `false'.

   * Driver will now use `INSERT INTO ... VALUES (DEFAULT)'form of
     statement for updatable result sets for `ResultSet.insertRow()',
     rather than pre-populating the insert row with values from
     `DatabaseMetaData.getColumns()'(which results in a `SHOW FULL
     COLUMNS' on the server for every result set). If an application
     requires access to the default values before `insertRow()' has been
     called, the JDBC URL should be configured with
     `populateInsertRowWithDefaultValues' set to `true'.

     This fix specifically targets performance issues with ColdFusion
     and the fact that it seems to ask for updatable result sets no
     matter what the application does with them.

   * More intelligent initial packet sizes for the "shared" packets are
     used (512 bytes, rather than 16K), and initial packets used during
     handshake are now sized appropriately as to not require
     reallocation.

Bugs fixed:

   * More useful error messages are generated when the driver thinks a
     result set is not updatable. (Thanks to Ashley Martens for the
     patch).  (Bug#28085 (http://bugs.mysql.com/28085))

   * `Connection.getTransactionIsolation()' uses "`SHOW VARIABLES
     LIKE'" which is very inefficient on MySQL-5.0+ servers.
     (Bug#27655 (http://bugs.mysql.com/27655))

   * Fixed issue where calling `getGeneratedKeys()' on a prepared
     statement after calling `execute()' didn't always return the
     generated keys (`executeUpdate()' worked fine however).
     (Bug#27655 (http://bugs.mysql.com/27655))

   * `CALL /* ... */ SOME_PROC()' doesn't work.  As a side effect of
     this fix, you can now use `/* */' and `#' comments when preparing
     statements using client-side prepared statement emulation.

     If the comments happen to contain parameter markers (`?'), they
     will be treated as belonging to the comment (that is, not
     recognized) rather than being a parameter of the statement.

     *Note*:

     The statement when sent to the server will contain the comments
     as-is, they're not stripped during the process of preparing the
     `PreparedStatement' or `CallableStatement'.

     (Bug#27400 (http://bugs.mysql.com/27400))

   * `ResultSet.get*()' with a column index < 1 returns misleading
     error message.  (Bug#27317 (http://bugs.mysql.com/27317))

   * Using `ResultSet.get*()' with a column index less than 1 returns a
     misleading error message.  (Bug#27317
     (http://bugs.mysql.com/27317))

   * Comments in DDL of stored procedures/functions confuse procedure
     parser, and thus metadata about them can not be created, leading
     to inability to retrieve said metadata, or execute procedures that
     have certain comments in them.  (Bug#26959
     (http://bugs.mysql.com/26959))

   * Fast date/time parsing doesn't take into account `00:00:00' as a
     legal value.  (Bug#26789 (http://bugs.mysql.com/26789))

   * `PreparedStatement' is not closed in `BlobFromLocator.getBytes()'.
     (Bug#26592 (http://bugs.mysql.com/26592))

   * When the configuration property `useCursorFetch' was set to
     `true', sometimes server would return new, more exact metadata
     during the execution of the server-side prepared statement that
     enables this functionality, which the driver ignored (using the
     original metadata returned during `prepare()'), causing corrupt
     reading of data due to type mismatch when the actual rows were
     returned.  (Bug#26173 (http://bugs.mysql.com/26173))

   * `CallableStatements' with `OUT/INOUT' parameters that are "binary"
     (`BLOB', `BIT', `(VAR)BINARY', `JAVA_OBJECT') have extra 7 bytes.
     (Bug#25715 (http://bugs.mysql.com/25715))

   * Whitespace surrounding storage/size specifiers in stored procedure
     parameters declaration causes `NumberFormatException' to be thrown
     when calling stored procedure on JDK-1.5 or newer, as the Number
     classes in JDK-1.5+ are whitespace intolerant.  (Bug#25624
     (http://bugs.mysql.com/25624))

   * Client options not sent correctly when using SSL, leading to
     stored procedures not being able to return results. Thanks to Don
     Cohen for the bug report, testcase and patch.  (Bug#25545
     (http://bugs.mysql.com/25545))

   * `Statement.setMaxRows()' is not effective on result sets
     materialized from cursors.  (Bug#25517
     (http://bugs.mysql.com/25517))

   * `BIT(> 1)' is returned as `java.lang.String' from
     `ResultSet.getObject()' rather than `byte[]'.  (Bug#25328
     (http://bugs.mysql.com/25328))


File: manual.info,  Node: cj-news-5-0-5,  Next: cj-news-5-0-4,  Prev: cj-news-5-0-6,  Up: cj-news-5-0

C.5.2.4 Changes in MySQL Connector/J 5.0.5 (02 March 2007)
..........................................................

Functionality added or changed:

   * Usage Advisor will now issue warnings for result sets with large
     numbers of rows. You can configure the trigger value by using the
     `resultSetSizeThreshold' parameter, which has a default value of
     100.

   * The `rewriteBatchedStatements' feature can now be used with
     server-side prepared statements.

   * *Important change:* Due to a number of issues with the use of
     server-side prepared statements, Connector/J 5.0.5 has disabled
     their use by default.  The disabling of server-side prepared
     statements does not affect the operation of the connector in any
     way.

     To enable server-side prepared statements you must add the
     following configuration property to your connector string:

          useServerPrepStmts=true

     The default value of this property is `false' (that is,
     Connector/J does not use server-side prepared statements).

   * Improved speed of `datetime' parsing for ResultSets that come from
     plain or non-server-side prepared statements. You can enable old
     implementation with `useFastDateParsing=false' as a configuration
     parameter.

   * Usage Advisor now detects empty results sets and does not report
     on columns not referenced in those empty sets.

   * Fixed logging of XA commands sent to server, it's now configurable
     via `logXaCommands' property (defaults to `false').

   * Added configuration property `localSocketAddress',which is the
     hostname or IP address given to explicitly configure the interface
     that the driver will bind the client side of the TCP/IP connection
     to when connecting.

   * We've added a new configuration option `treatUtilDateAsTimestamp',
     which is `false' by default, as (1) We already had specific
     behavior to treat java.util.Date as a java.sql.Timestamp because
     it's useful to many folks, and (2) that behavior will very likely
     be required for drivers JDBC-post-4.0.

Bugs fixed:

   * Connection property `socketFactory' wasn't exposed via correctly
     named mutator/accessor, causing data source implementations that
     use JavaBean naming conventions to set properties to fail to set
     the property (and in the case of SJAS, fail silently when trying
     to set this parameter).  (Bug#26326 (http://bugs.mysql.com/26326))

   * A query execution which timed out did not always throw a
     `MySQLTimeoutException'.  (Bug#25836 (http://bugs.mysql.com/25836))

   * Storing a `java.util.Date' object in a `BLOB' column would not be
     serialized correctly during `setObject'.  (Bug#25787
     (http://bugs.mysql.com/25787))

   * Timer instance used for `Statement.setQueryTimeout()' created
     per-connection, rather than per-VM, causing memory leak.
     (Bug#25514 (http://bugs.mysql.com/25514))

   * `EscapeProcessor' gets confused by multiple backslashes. We now
     push the responsibility of syntax errors back on to the server for
     most escape sequences.  (Bug#25399 (http://bugs.mysql.com/25399))

   * `INOUT' parameters in `CallableStatements' get doubly-escaped.
     (Bug#25379 (http://bugs.mysql.com/25379))

   * When using the `rewriteBatchedStatements' connection option with
     `PreparedState.executeBatch()' an internal memory leak would occur.
     (Bug#25073 (http://bugs.mysql.com/25073))

   * Fixed issue where field-level for metadata from `DatabaseMetaData'
     when using `INFORMATION_SCHEMA' didn't have references to current
     connections, sometimes leading to Null Pointer Exceptions (NPEs)
     when introspecting them via `ResultSetMetaData'.  (Bug#25073
     (http://bugs.mysql.com/25073))

   * `StringUtils.indexOfIgnoreCaseRespectQuotes()' isn't
     case-insensitive on the first character of the target.  This bug
     also affected `rewriteBatchedStatements' functionality when
     prepared statements did not use uppercase for the `VALUES' clause.
     (Bug#25047 (http://bugs.mysql.com/25047))

   * Client-side prepared statement parser gets confused by in-line
     comments `/*...*/' and therefore cannot rewrite batch statements
     or reliably detect the type of statements when they are used.
     (Bug#25025 (http://bugs.mysql.com/25025))

   * Results sets from `UPDATE' statements that are part of
     multi-statement queries would cause an `SQLException' error,
     "Result is from UPDATE".  (Bug#25009 (http://bugs.mysql.com/25009))

   * Specifying `US-ASCII' as the character set in a connection to a
     MySQL 4.1 or newer server does not map correctly.  (Bug#24840
     (http://bugs.mysql.com/24840))

   * Using `DatabaseMetaData.getSQLKeywords()' does not return a all of
     the of the reserved keywords for the current MySQL version.
     Current implementation returns the list of reserved words for
     MySQL 5.1, and does not distinguish between versions.  (Bug#24794
     (http://bugs.mysql.com/24794))

   * Calling `Statement.cancel()' could result in a Null Pointer
     Exception (NPE).  (Bug#24721 (http://bugs.mysql.com/24721))

   * Using `setFetchSize()' breaks prepared `SHOW' and other commands.
     (Bug#24360 (http://bugs.mysql.com/24360))

   * Calendars and timezones are now lazily instantiated when required.
     (Bug#24351 (http://bugs.mysql.com/24351))

   * Using `DATETIME' columns would result in time shifts when
     `useServerPrepStmts' was true. The reason was due to different
     behavior when using client-side compared to server-side prepared
     statements and the `useJDBCCompliantTimezoneShift' option. This is
     now fixed if moving from server-side prepared statements to
     client-side prepared statements by setting
     `useSSPSCompatibleTimezoneShift' to `true', as the driver can't
     tell if this is a new deployment that never used server-side
     prepared statements, or if it is an existing deployment that is
     switching to client-side prepared statements from server-side
     prepared statements.  (Bug#24344 (http://bugs.mysql.com/24344))

   * Connector/J now returns a better error message when server doesn't
     return enough information to determine stored procedure/function
     parameter types.  (Bug#24065 (http://bugs.mysql.com/24065))

   * A connection error would occur when connecting to a MySQL server
     with certain character sets. Some collations/character sets
     reported as "unknown" (specifically `cias' variants of existing
     character sets), and inability to override the detected server
     character set.  (Bug#23645 (http://bugs.mysql.com/23645))

   * Inconsistency between `getSchemas' and `INFORMATION_SCHEMA'.
     (Bug#23304 (http://bugs.mysql.com/23304))

   * `DatabaseMetaData.getSchemas()' doesn't return a `TABLE_CATALOG'
     column.  (Bug#23303 (http://bugs.mysql.com/23303))

   * When using a JDBC connection URL that is malformed, the
     `NonRegisteringDriver.getPropertyInfo' method will throw a Null
     Pointer Exception (NPE).  (Bug#22628 (http://bugs.mysql.com/22628))

   * Some exceptions thrown out of `StandardSocketFactory' were
     needlessly wrapped, obscuring their true cause, especially when
     using socket timeouts.  (Bug#21480 (http://bugs.mysql.com/21480))

   * When using a server-side prepared statement the driver would send
     timestamps to the server using nanoseconds instead of milliseconds.
     (Bug#21438 (http://bugs.mysql.com/21438))

   * When using server-side prepared statements and timestamp columns,
     value would be incorrectly populated (with nanoseconds, not
     microseconds).  (Bug#21438 (http://bugs.mysql.com/21438))

   * `ParameterMetaData' throws `NullPointerException' when prepared
     SQL has a syntax error. Added `generateSimpleParameterMetadata'
     configuration property, which when set to `true' will generate
     metadata reflecting `VARCHAR' for every parameter (the default is
     `false', which will cause an exception to be thrown if no
     parameter metadata for the statement is actually available).
     (Bug#21267 (http://bugs.mysql.com/21267))

   * Fixed an issue where `XADataSources' couldn't be bound into JNDI,
     as the `DataSourceFactory' didn't know how to create instances of
     them.

Other changes:

   * Avoid static synchronized code in JVM class libraries for dealing
     with default timezones.

   * Performance enhancement of initial character set configuration,
     driver will only send commands required to configure connection
     character set session variables if the current values on the
     server do not match what is required.

   * Re-worked stored procedure parameter parser to be more robust.
     Driver no longer requires `BEGIN' in stored procedure definition,
     but does have requirement that if a stored function begins with a
     label directly after the "returns" clause, that the label is not a
     quoted identifier.

   * Throw exceptions encountered during timeout to thread calling
     `Statement.execute*()', rather than `RuntimeException'.

   * Changed cached result set metadata (when using
     `cacheResultSetMetadata=true') to be cached per-connection rather
     than per-statement as previously implemented.

   * Reverted back to internal character conversion routines for
     single-byte character sets, as the ones internal to the JVM are
     using much more CPU time than our internal implementation.

   * When extracting foreign key information from `SHOW CREATE TABLE'
     in `DatabaseMetaData', ignore exceptions relating to tables being
     missing (which could happen for cross-reference or imported-key
     requests, as the list of tables is generated first, then iterated).

   * Fixed some Null Pointer Exceptions (NPEs) when cached metadata was
     used with `UpdatableResultSets'.

   * Take `localSocketAddress' property into account when creating
     instances of `CommunicationsException' when the underyling
     exception is a `java.net.BindException', so that a friendlier
     error message is given with a little internal diagnostics.

   * Fixed cases where `ServerPreparedStatements' weren't using cached
     metadata when `cacheResultSetMetadata=true' was used.

   * Use a `java.util.TreeMap' to map column names to ordinal indexes
     for `ResultSet.findColumn()' instead of a HashMap. This allows us
     to have case-insensitive lookups (required by the JDBC
     specification) without resorting to the many transient object
     instances needed to support this requirement with a normal
     `HashMap' with either case-adjusted keys, or case-insensitive
     keys. (In the worst case scenario for lookups of a 1000 column
     result set, TreeMaps are about half as fast wall-clock time as a
     HashMap, however in normal applications their use gives many
     orders of magnitude reduction in transient object instance
     creation which pays off later for CPU usage in garbage collection).

   * When using cached metadata, skip field-level metadata packets
     coming from the server, rather than reading them and discarding
     them without creating `com.mysql.jdbc.Field' instances.


File: manual.info,  Node: cj-news-5-0-4,  Next: cj-news-5-0-3,  Prev: cj-news-5-0-5,  Up: cj-news-5-0

C.5.2.5 Changes in MySQL Connector/J 5.0.4 (20 October 2006)
............................................................

Bugs fixed:

   * DBMD.getColumns() does not return expected COLUMN_SIZE for the SET
     type, now returns length of largest possible set disregarding
     whitespace or the "," delimitters to be consistent with the ODBC
     driver.  (Bug#22613 (http://bugs.mysql.com/22613))

   * Added new _ci collations to CharsetMapping - utf8_unicode_ci not
     working.  (Bug#22456 (http://bugs.mysql.com/22456))

   * Driver was using milliseconds for Statement.setQueryTimeout() when
     specification says argument is to be in seconds.  (Bug#22359
     (http://bugs.mysql.com/22359))

   * Workaround for server crash when calling stored procedures via a
     server-side prepared statement (driver now detects prepare(stored
     procedure) and substitutes client-side prepared statement).
     (Bug#22297 (http://bugs.mysql.com/22297))

   * Driver issues truncation on write exception when it shouldn't (due
     to sending big decimal incorrectly to server with server-side
     prepared statement).  (Bug#22290 (http://bugs.mysql.com/22290))

   * Newlines causing whitespace to span confuse procedure parser when
     getting parameter metadata for stored procedures.  (Bug#22024
     (http://bugs.mysql.com/22024))

   * When using information_schema for metadata, COLUMN_SIZE for
     getColumns() is not clamped to range of java.lang.Integer as is
     the case when not using information_schema, thus leading to a
     truncation exception that isn't present when not using
     information_schema.  (Bug#21544 (http://bugs.mysql.com/21544))

   * Column names don't match metadata in cases where server doesn't
     return original column names (column functions) thus breaking
     compatibility with applications that expect 1-1 mappings between
     findColumn() and rsmd.getColumnName(), usually manifests itself as
     "Can't find column (")" exceptions.  (Bug#21379
     (http://bugs.mysql.com/21379))

   * Driver now sends numeric 1 or 0 for client-prepared statement
     `setBoolean()' calls instead of '1' or '0'.

   * Fixed configuration property `jdbcCompliantTruncation' was not
     being used for reads of result set values.

   * DatabaseMetaData correctly reports `true' for `supportsCatalog*()'
     methods.

   * Driver now supports `{call sp}' (without "()" if procedure has no
     arguments).


File: manual.info,  Node: cj-news-5-0-3,  Next: cj-news-5-0-2,  Prev: cj-news-5-0-4,  Up: cj-news-5-0

C.5.2.6 Changes in MySQL Connector/J 5.0.3 (26 July 2006)
.........................................................

Functionality added or changed:

   * Added configuration option `noAccessToProcedureBodies' which will
     cause the driver to create basic parameter metadata for
     `CallableStatements' when the user does not have access to
     procedure bodies via `SHOW CREATE PROCEDURE' or selecting from
     `mysql.proc' instead of throwing an exception.  The default value
     for this option is `false'

Bugs fixed:

   * Fixed `Statement.cancel()' causes `NullPointerException' if
     underlying connection has been closed due to server failure.
     (Bug#20650 (http://bugs.mysql.com/20650))

   * If the connection to the server has been closed due to a server
     failure, then the cleanup process will call ` Statement.cancel()',
     triggering a `NullPointerException', even though there is no
     active connection.  (Bug#20650 (http://bugs.mysql.com/20650))


File: manual.info,  Node: cj-news-5-0-2,  Next: cj-news-5-0-1,  Prev: cj-news-5-0-3,  Up: cj-news-5-0

C.5.2.7 Changes in MySQL Connector/J 5.0.2 (11 July 2006)
.........................................................

Bugs fixed:

   * `MysqlXaConnection.recover(int flags)' now allows combinations of
     `XAResource.TMSTARTRSCAN' and `TMENDRSCAN'. To simulate the
     `scanning' nature of the interface, we return all prepared XIDs
     for `TMSTARTRSCAN', and no new XIDs for calls with `TMNOFLAGS', or
     `TMENDRSCAN' when not in combination with `TMSTARTRSCAN'. This
     change was made for API compliance, as well as integration with
     IBM WebSphere's transaction manager.  (Bug#20242
     (http://bugs.mysql.com/20242))

   * Fixed `MysqlValidConnectionChecker' for JBoss doesn't work with
     `MySQLXADataSources'.  (Bug#20242 (http://bugs.mysql.com/20242))

   * Added connection/datasource property
     `pinGlobalTxToPhysicalConnection' (defaults to `false'). When set
     to `true', when using `XAConnections', the driver ensures that
     operations on a given XID are always routed to the same physical
     connection. This allows the `XAConnection' to support `XA START ...
     JOIN' after `XA END' has been called, and is also a workaround for
     transaction managers that don't maintain thread affinity for a
     global transaction (most either always maintain thread affinity,
     or have it as a configuration option).  (Bug#20242
     (http://bugs.mysql.com/20242))

   * Better caching of character set converters (per-connection) to
     remove a bottleneck for multibyte character sets.  (Bug#20242
     (http://bugs.mysql.com/20242))

   * Fixed `ConnectionProperties' (and thus some subclasses) are not
     serializable, even though some J2EE containers expect them to be.
     (Bug#19169 (http://bugs.mysql.com/19169))

   * Fixed driver fails on non-ASCII platforms. The driver was assuming
     that the platform character set would be a superset of MySQL's
     `latin1' when doing the handshake for authentication, and when
     reading error messages. We now use Cp1252 for all strings sent to
     the server during the handshake phase, and a hard-coded mapping of
     the `language' systtem variable to the character set that is used
     for error messages.  (Bug#18086 (http://bugs.mysql.com/18086))

   * Fixed can't use `XAConnection' for local transactions when no
     global transaction is in progress.  (Bug#17401
     (http://bugs.mysql.com/17401))


File: manual.info,  Node: cj-news-5-0-1,  Next: cj-news-5-0-0,  Prev: cj-news-5-0-2,  Up: cj-news-5-0

C.5.2.8 Changes in MySQL Connector/J 5.0.1 (Not Released)
.........................................................

Not released due to a packaging error


File: manual.info,  Node: cj-news-5-0-0,  Prev: cj-news-5-0-1,  Up: cj-news-5-0

C.5.2.9 Changes in MySQL Connector/J 5.0.0 (22 December 2005)
.............................................................

Bugs fixed:

   * Added support for Connector/MXJ integration via url subprotocol
     `jdbc:mysql:mxj://...'.  (Bug#14729 (http://bugs.mysql.com/14729))

   * Idle timeouts cause `XAConnections' to whine about rolling
     themselves back.  (Bug#14729 (http://bugs.mysql.com/14729))

   * When fix for Bug#14562 (http://bugs.mysql.com/14562) was merged
     from 3.1.12, added functionality for `CallableStatement''s
     parameter metadata to return correct information for
     `.getParameterClassName()'.  (Bug#14729
     (http://bugs.mysql.com/14729))

   * Added service-provider entry to
     `META-INF/services/java.sql.Driver' for JDBC-4.0 support.
     (Bug#14729 (http://bugs.mysql.com/14729))

   * Fuller synchronization of `Connection' to avoid deadlocks when
     using multithreaded frameworks that multithread a single
     connection (usually not recommended, but the JDBC spec allows it
     anyways), part of fix to Bug#14972 (http://bugs.mysql.com/14972)).
     (Bug#14729 (http://bugs.mysql.com/14729))

   * Moved all `SQLException' constructor usage to a factory in
     `SQLError' (ground-work for JDBC-4.0 `SQLState'-based exception
     classes).  (Bug#14729 (http://bugs.mysql.com/14729))

   * Removed Java5-specific calls to `BigDecimal' constructor (when
     result set value is `''', `(int)0' was being used as an argument
     indirectly via method return value. This signature doesn't exist
     prior to Java5.)  (Bug#14729 (http://bugs.mysql.com/14729))

   * Implementation of `Statement.cancel()' and
     `Statement.setQueryTimeout()'. Both require MySQL-5.0.0 or newer
     server, require a separate connection to issue the `KILL QUERY'
     statement, and in the case of `setQueryTimeout()' creates an
     additional thread to handle the timeout functionality.

     Note: Failures to cancel the statement for `setQueryTimeout()' may
     manifest themselves as `RuntimeExceptions' rather than failing
     silently, as there is currently no way to unblock the thread that
     is executing the query being cancelled due to timeout expiration
     and have it throw the exception instead.  (Bug#14729
     (http://bugs.mysql.com/14729))

   * Return "[VAR]BINARY" for `RSMD.getColumnTypeName()' when that is
     actually the type, and it can be distinguished (MySQL-4.1 and
     newer).  (Bug#14729 (http://bugs.mysql.com/14729))

   * Attempt detection of the MySQL type `BINARY' (it's an alias, so
     this isn't always reliable), and use the `java.sql.Types.BINARY'
     type mapping for it.

   * Added unit tests for `XADatasource', as well as friendlier
     exceptions for XA failures compared to the "stock" `XAException'
     (which has no messages).

   * If the connection `useTimezone' is set to `true', then also
     respect time zone conversions in escape-processed string literals
     (for example, `"{ts ...}"' and `"{t ...}"').

   * Don't allow `.setAutoCommit(true)', or `.commit()' or `.rollback()'
     on an XA-managed connection as per the JDBC specification.

   * `XADataSource' implemented (ported from 3.2 branch which won't be
     released as a product). Use
     `com.mysql.jdbc.jdbc2.optional.MysqlXADataSource' as your
     datasource class name in your application server to utilize XA
     transactions in MySQL-5.0.10 and newer.

   * Moved `-bin-g.jar' file into separate `debug' subdirectory to
     avoid confusion.

   * Return original column name for `RSMD.getColumnName()' if the
     column was aliased, alias name for `.getColumnLabel()' (if
     aliased), and original table name for `.getTableName()'. Note this
     only works for MySQL-4.1 and newer, as older servers don't make
     this information available to clients.

   * Setting `useJDBCCompliantTimezoneShift=true' (it's not the
     default) causes the driver to use GMT for _all_
     `TIMESTAMP'/`DATETIME' time zones, and the current VM time zone
     for any other type that refers to time zones. This feature can not
     be used when `useTimezone=true' to convert between server and
     client time zones.

   * `PreparedStatement.setString()' didn't work correctly when
     `sql_mode' on server contained `NO_BACKSLASH_ESCAPES' and no
     characters that needed escaping were present in the string.

   * Add one level of indirection of internal representation of
     `CallableStatement' parameter metadata to avoid class not found
     issues on JDK-1.3 for `ParameterMetadata' interface (which doesn't
     exist prior to JDBC-3.0).


File: manual.info,  Node: cg-news-3-1,  Next: cg-news-3-0,  Prev: cj-news-5-0,  Up: cj-news

C.5.3 Changes in MySQL Connector/J 3.1.x
----------------------------------------

* Menu:

* cj-news-3-1-15::               Changes in MySQL Connector/J 3.1.15 (Not yet released)
* cj-news-3-1-14::               Changes in MySQL Connector/J 3.1.14 (10-19-2006)
* cj-news-3-1-13::               Changes in MySQL Connector/J 3.1.13 (26 May 2006)
* cj-news-3-1-12::               Changes in MySQL Connector/J 3.1.12 (30 November 2005)
* cj-news-3-1-11::               Changes in MySQL Connector/J 3.1.11 (07 October 2005)
* cj-news-3-1-10::               Changes in MySQL Connector/J 3.1.10 (23 June 2005)
* cj-news-3-1-9::                Changes in MySQL Connector/J 3.1.9 (22 June 2005)
* cj-news-3-1-8::                Changes in MySQL Connector/J 3.1.8 (14 April 2005)
* cj-news-3-1-7::                Changes in MySQL Connector/J 3.1.7 (18 February 2005)
* cj-news-3-1-6::                Changes in MySQL Connector/J 3.1.6 (23 December 2004)
* cj-news-3-1-5::                Changes in MySQL Connector/J 3.1.5 (02 December 2004)
* cj-news-3-1-4::                Changes in MySQL Connector/J 3.1.4 (04 September 2004)
* cj-news-3-1-3::                Changes in MySQL Connector/J 3.1.3 (07 July 2004)
* cj-news-3-1-2::                Changes in MySQL Connector/J 3.1.2 (09 June 2004)
* cj-news-3-1-1::                Changes in MySQL Connector/J 3.1.1 (14 February 2004)
* cj-news-3-1-0::                Changes in MySQL Connector/J 3.1.0 (18 February 2003)


File: manual.info,  Node: cj-news-3-1-15,  Next: cj-news-3-1-14,  Prev: cg-news-3-1,  Up: cg-news-3-1

C.5.3.1 Changes in MySQL Connector/J 3.1.15 (Not yet released)
..............................................................

*Important change:* Due to a number of issues with the use of
server-side prepared statements, Connector/J 5.0.5 has disabled their
use by default.  The disabling of server-side prepared statements does
not affect the operation of the connector in any way.

To enable server-side prepared statements you must add the following
configuration property to your connector string:

     useServerPrepStmts=true

The default value of this property is `false' (that is, Connector/J
does not use server-side prepared statements).

Bugs fixed:

   * Specifying `US-ASCII' as the character set in a connection to a
     MySQL 4.1 or newer server does not map correctly.  (Bug#24840
     (http://bugs.mysql.com/24840))


File: manual.info,  Node: cj-news-3-1-14,  Next: cj-news-3-1-13,  Prev: cj-news-3-1-15,  Up: cg-news-3-1

C.5.3.2 Changes in MySQL Connector/J 3.1.14 (10-19-2006)
........................................................

Bugs fixed:

   * Check and store value for continueBatchOnError property in
     constructor of Statements, rather than when executing batches, so
     that Connections closed out from underneath statements don't cause
     NullPointerExceptions when it's required to check this property.
     (Bug#22290 (http://bugs.mysql.com/22290))

   * Fixed Bug#18258 (http://bugs.mysql.com/18258) -
     DatabaseMetaData.getTables(), columns() with bad catalog parameter
     threw exception rather than return empty result set (as required
     by spec).  (Bug#22290 (http://bugs.mysql.com/22290))

   * Driver now sends numeric 1 or 0 for client-prepared statement
     setBoolean() calls instead of '1' or '0'.  (Bug#22290
     (http://bugs.mysql.com/22290))

   * Fixed bug where driver would not advance to next host if
     roundRobinLoadBalance=true and the last host in the list is down.
     (Bug#22290 (http://bugs.mysql.com/22290))

   * Driver issues truncation on write exception when it shouldn't (due
     to sending big decimal incorrectly to server with server-side
     prepared statement).  (Bug#22290 (http://bugs.mysql.com/22290))

   * Fixed bug when calling stored functions, where parameters weren't
     numbered correctly (first parameter is now the return value,
     subsequent parameters if specified start at index "2").
     (Bug#22290 (http://bugs.mysql.com/22290))

   * Removed logger autodetection altogether, must now specify logger
     explicitly if you want to use a logger other than one that logs to
     STDERR.  (Bug#21207 (http://bugs.mysql.com/21207))

   * DDriver throws NPE when tracing prepared statements that have been
     closed (in asSQL()).  (Bug#21207 (http://bugs.mysql.com/21207))

   * ResultSet.getSomeInteger() doesn't work for BIT(>1).  (Bug#21062
     (http://bugs.mysql.com/21062))

   * Escape of quotes in client-side prepared statements parsing not
     respected. Patch covers more than bug report, including
     NO_BACKSLASH_ESCAPES being set, and stacked quote characters forms
     of escaping (that is, " or "").  (Bug#20888
     (http://bugs.mysql.com/20888))

   * Fixed can't pool server-side prepared statements, exception raised
     when re-using them.  (Bug#20687 (http://bugs.mysql.com/20687))

   * Fixed Updatable result set that contains a BIT column fails when
     server-side prepared statements are used.  (Bug#20485
     (http://bugs.mysql.com/20485))

   * Fixed updatable result set throws ClassCastException when there is
     row data and moveToInsertRow() is called.  (Bug#20479
     (http://bugs.mysql.com/20479))

   * Fixed ResultSet.getShort() for UNSIGNED TINYINT returns incorrect
     values when using server-side prepared statements.  (Bug#20306
     (http://bugs.mysql.com/20306))

   * ReplicationDriver does not always round-robin load balance
     depending on URL used for slaves list.  (Bug#19993
     (http://bugs.mysql.com/19993))

   * Fixed calling toString() on ResultSetMetaData for driver-generated
     (that is, from DatabaseMetaData method calls, or from
     getGeneratedKeys()) result sets would raise a NullPointerException.
     (Bug#19993 (http://bugs.mysql.com/19993))

   * Connection fails to localhost when using timeout and IPv6 is
     configured.  (Bug#19726 (http://bugs.mysql.com/19726))

   * ResultSet.getFloatFromString() can't retrieve values near
     Float.MIN/MAX_VALUE.  (Bug#18880 (http://bugs.mysql.com/18880))

   * Fixed memory leak with profileSQL=true.  (Bug#16987
     (http://bugs.mysql.com/16987))

   * Fixed NullPointerException in MysqlDataSourceFactory due to
     Reference containing RefAddrs with null content.  (Bug#16791
     (http://bugs.mysql.com/16791))


File: manual.info,  Node: cj-news-3-1-13,  Next: cj-news-3-1-12,  Prev: cj-news-3-1-14,  Up: cg-news-3-1

C.5.3.3 Changes in MySQL Connector/J 3.1.13 (26 May 2006)
.........................................................

Bugs fixed:

   * `Fixed PreparedStatement.setObject(int, Object, int)' doesn't
     respect scale of BigDecimals.  (Bug#19615
     (http://bugs.mysql.com/19615))

   * Fixed `ResultSet.wasNull()' returns incorrect value when
     extracting native string from server-side prepared statement
     generated result set.  (Bug#19282 (http://bugs.mysql.com/19282))

   * Fixed invalid classname returned for
     `ResultSetMetaData.getColumnClassName()' for `BIGINT type'.
     (Bug#19282 (http://bugs.mysql.com/19282))

   * Fixed case where driver wasn't reading server status correctly
     when fetching server-side prepared statement rows, which in some
     cases could cause warning counts to be off, or multiple result
     sets to not be read off the wire.  (Bug#19282
     (http://bugs.mysql.com/19282))

   * Fixed data truncation and `getWarnings()' only returns last
     warning in set.  (Bug#18740 (http://bugs.mysql.com/18740))

   * Fixed aliased column names where length of name > 251 are
     corrupted.  (Bug#18554 (http://bugs.mysql.com/18554))

   * Improved performance of retrieving `BigDecimal', `Time',
     `Timestamp' and `Date' values from server-side prepared statements
     by creating fewer short-lived instances of `Strings' when the
     native type is not an exact match for the requested type.
     (Bug#18496 (http://bugs.mysql.com/18496))

   * Added performance feature, re-writing of batched executes for
     `Statement.executeBatch()' (for all DML statements) and
     `PreparedStatement.executeBatch()' (for INSERTs with VALUE clauses
     only). Enable by using "rewriteBatchedStatements=true" in your
     JDBC URL.  (Bug#18041 (http://bugs.mysql.com/18041))

   * Fixed issue where server-side prepared statements don't cause
     truncation exceptions to be thrown when truncation happens.
     (Bug#18041 (http://bugs.mysql.com/18041))

   * Fixed `CallableStatement.registerOutParameter()' not working when
     some parameters pre-populated. Still waiting for feedback from
     JDBC experts group to determine what correct parameter count from
     `getMetaData()' should be, however.  (Bug#17898
     (http://bugs.mysql.com/17898))

   * Fixed calling `clearParameters()' on a closed prepared statement
     causes NPE.  (Bug#17587 (http://bugs.mysql.com/17587))

   * Map "latin1" on MySQL server to CP1252 for MySQL > 4.1.0.
     (Bug#17587 (http://bugs.mysql.com/17587))

   * Added additional accessor and mutator methods on
     ConnectionProperties so that DataSource users can use same naming
     as regular URL properties.  (Bug#17587
     (http://bugs.mysql.com/17587))

   * Fixed `ResultSet.wasNull()' not always reset correctly for
     booleans when done via conversion for server-side prepared
     statements.  (Bug#17450 (http://bugs.mysql.com/17450))

   * Fixed `Statement.getGeneratedKeys()' throws `NullPointerException'
     when no query has been processed.  (Bug#17099
     (http://bugs.mysql.com/17099))

   * Fixed updatable result set doesn't return `AUTO_INCREMENT' values
     for `insertRow()' when multiple column primary keys are used. (the
     driver was checking for the existence of single-column primary
     keys and an autoincrement value > 0 instead of a straightforward
     `isAutoIncrement()' check).  (Bug#16841
     (http://bugs.mysql.com/16841))

   * `DBMD.getColumns()' returns wrong type for `BIT'.  (Bug#15854
     (http://bugs.mysql.com/15854))

   * `lib-nodist' directory missing from package breaks out-of-box
     build.  (Bug#15676 (http://bugs.mysql.com/15676))

   * Fixed issue with `ReplicationConnection' incorrectly copying
     state, doesn't transfer connection context correctly when
     transitioning between the same read-only states.  (Bug#15570
     (http://bugs.mysql.com/15570))

   * No "dos" character set in MySQL > 4.1.0.  (Bug#15544
     (http://bugs.mysql.com/15544))

   * `INOUT' parameter does not store `IN' value.  (Bug#15464
     (http://bugs.mysql.com/15464))

   * `PreparedStatement.setObject()' serializes `BigInteger' as object,
     rather than sending as numeric value (and is thus not
     complementary to `.getObject()' on an `UNSIGNED LONG' type).
     (Bug#15383 (http://bugs.mysql.com/15383))

   * Fixed issue where driver was unable to initialize character set
     mapping tables. Removed reliance on `.properties' files to hold
     this information, as it turns out to be too problematic to code
     around class loader hierarchies that change depending on how an
     application is deployed. Moved information back into the
     `CharsetMapping' class.  (Bug#14938 (http://bugs.mysql.com/14938))

   * Exception thrown for new decimal type when using updatable result
     sets.  (Bug#14609 (http://bugs.mysql.com/14609))

   * Driver now aware of fix for `BIT' type metadata that went into
     MySQL-5.0.21 for server not reporting length consistently .
     (Bug#13601 (http://bugs.mysql.com/13601))

   * Added support for Apache Commons logging, use
     "com.mysql.jdbc.log.CommonsLogger" as the value for the "logger"
     configuration property.  (Bug#13469 (http://bugs.mysql.com/13469))

   * Fixed driver trying to call methods that don't exist on older and
     newer versions of Log4j. The fix is not trying to auto-detect
     presence of log4j, too many different incompatible versions out
     there in the wild to do this reliably.

     If you relied on autodetection before, you will need to add
     "logger=com.mysql.jdbc.log.Log4JLogger" to your JDBC URL to enable
     Log4J usage, or alternatively use the new "CommonsLogger" class to
     take care of this.  (Bug#13469 (http://bugs.mysql.com/13469))

   * LogFactory now prepends "com.mysql.jdbc.log" to log class name if
     it can't be found as-specified. This allows you to use "short
     names" for the built-in log factories, for example
     "logger=CommonsLogger" instead of
     "logger=com.mysql.jdbc.log.CommonsLogger".  (Bug#13469
     (http://bugs.mysql.com/13469))

   * `ResultSet.getShort()' for `UNSIGNED TINYINT' returned wrong
     values.  (Bug#11874 (http://bugs.mysql.com/11874))


File: manual.info,  Node: cj-news-3-1-12,  Next: cj-news-3-1-11,  Prev: cj-news-3-1-13,  Up: cg-news-3-1

C.5.3.4 Changes in MySQL Connector/J 3.1.12 (30 November 2005)
..............................................................

Bugs fixed:

   * Process escape tokens in `Connection.prepareStatement(...)'. You
     can disable this behavior by setting the JDBC URL configuration
     property `processEscapeCodesForPrepStmts' to `false'.  (Bug#15141
     (http://bugs.mysql.com/15141))

   * Usage advisor complains about unreferenced columns, even though
     they've been referenced.  (Bug#15065 (http://bugs.mysql.com/15065))

   * Driver incorrectly closes streams passed as arguments to
     `PreparedStatements'. Reverts to legacy behavior by setting the
     JDBC configuration property `autoClosePStmtStreams' to `true'
     (also included in the 3-0-Compat configuration `bundle').
     (Bug#15024 (http://bugs.mysql.com/15024))

   * Deadlock while closing server-side prepared statements from
     multiple threads sharing one connection.  (Bug#14972
     (http://bugs.mysql.com/14972))

   * Unable to initialize character set mapping tables (due to J2EE
     classloader differences).  (Bug#14938
     (http://bugs.mysql.com/14938))

   * Escape processor replaces quote character in quoted string with
     string delimiter.  (Bug#14909 (http://bugs.mysql.com/14909))

   * `DatabaseMetaData.getColumns()' doesn't return `TABLE_NAME'
     correctly.  (Bug#14815 (http://bugs.mysql.com/14815))

   * `storesMixedCaseIdentifiers()' returns `false' (Bug#14562
     (http://bugs.mysql.com/14562))

   * `storesLowerCaseIdentifiers()' returns `true' (Bug#14562
     (http://bugs.mysql.com/14562))

   * `storesMixedCaseQuotedIdentifiers()' returns `false' (Bug#14562
     (http://bugs.mysql.com/14562))

   * `storesMixedCaseQuotedIdentifiers()' returns `true' (Bug#14562
     (http://bugs.mysql.com/14562))

   * If `lower_case_table_names=0' (on server):

        * `storesLowerCaseIdentifiers()' returns `false'

        * `storesLowerCaseQuotedIdentifiers()' returns `false'

        * `storesMixedCaseIdentifiers()' returns `true'

        * `storesMixedCaseQuotedIdentifiers()' returns `true'

        * `storesUpperCaseIdentifiers()' returns `false'

        * `storesUpperCaseQuotedIdentifiers()' returns `true'

     (Bug#14562 (http://bugs.mysql.com/14562))

   * `storesUpperCaseIdentifiers()' returns `false' (Bug#14562
     (http://bugs.mysql.com/14562))

   * `storesUpperCaseQuotedIdentifiers()' returns `true' (Bug#14562
     (http://bugs.mysql.com/14562))

   * If `lower_case_table_names=1' (on server):

        * `storesLowerCaseIdentifiers()' returns `true'

        * `storesLowerCaseQuotedIdentifiers()' returns `true'

        * `storesMixedCaseIdentifiers()' returns `false'

        * `storesMixedCaseQuotedIdentifiers()' returns `false'

        * `storesUpperCaseIdentifiers()' returns `false'

        * `storesUpperCaseQuotedIdentifiers()' returns `true'

     (Bug#14562 (http://bugs.mysql.com/14562))

   * `storesLowerCaseQuotedIdentifiers()' returns `true' (Bug#14562
     (http://bugs.mysql.com/14562))

   * Fixed `DatabaseMetaData.stores*Identifiers()':

        * If `lower_case_table_names=0' (on server):

             * `storesLowerCaseIdentifiers()' returns `false'

             * `storesLowerCaseQuotedIdentifiers()' returns `false'

             * `storesMixedCaseIdentifiers()' returns `true'

             * `storesMixedCaseQuotedIdentifiers()' returns `true'

             * `storesUpperCaseIdentifiers()' returns `false'

             * `storesUpperCaseQuotedIdentifiers()' returns `true'

        * If `lower_case_table_names=1' (on server):

             * `storesLowerCaseIdentifiers()' returns `true'

             * `storesLowerCaseQuotedIdentifiers()' returns `true'

             * `storesMixedCaseIdentifiers()' returns `false'

             * `storesMixedCaseQuotedIdentifiers()' returns `false'

             * `storesUpperCaseIdentifiers()' returns `false'

             * `storesUpperCaseQuotedIdentifiers()' returns `true'

     (Bug#14562 (http://bugs.mysql.com/14562))

   * `storesMixedCaseIdentifiers()' returns `true' (Bug#14562
     (http://bugs.mysql.com/14562))

   * `storesLowerCaseQuotedIdentifiers()' returns `false' (Bug#14562
     (http://bugs.mysql.com/14562))

   * Java type conversion may be incorrect for `MEDIUMINT'.  (Bug#14562
     (http://bugs.mysql.com/14562))

   * `storesLowerCaseIdentifiers()' returns `false' (Bug#14562
     (http://bugs.mysql.com/14562))

   * Added configuration property `useGmtMillisForDatetimes' which when
     set to `true' causes `ResultSet.getDate()', `.getTimestamp()' to
     return correct millis-since GMT when `.getTime()' is called on the
     return value (currently default is `false' for legacy behavior).
     (Bug#14562 (http://bugs.mysql.com/14562))

   * Extraneous sleep on `autoReconnect'.  (Bug#13775
     (http://bugs.mysql.com/13775))

   * Reconnect during middle of `executeBatch()' should not occur if
     `autoReconnect' is enabled.  (Bug#13255
     (http://bugs.mysql.com/13255))

   * `maxQuerySizeToLog' is not respected. Added logging of bound
     values for `execute()' phase of server-side prepared statements
     when `profileSQL=true' as well.  (Bug#13048
     (http://bugs.mysql.com/13048))

   * OpenOffice expects `DBMD.supportsIntegrityEnhancementFacility()'
     to return `true' if foreign keys are supported by the datasource,
     even though this method also covers support for check constraints,
     which MySQL _doesn't_ have. Setting the configuration property
     `overrideSupportsIntegrityEnhancementFacility' to `true' causes
     the driver to return `true' for this method.  (Bug#12975
     (http://bugs.mysql.com/12975))

   * Added `com.mysql.jdbc.testsuite.url.default' system property to
     set default JDBC url for testsuite (to speed up bug resolution
     when I'm working in Eclipse).  (Bug#12975
     (http://bugs.mysql.com/12975))

   * `logSlowQueries' should give better info.  (Bug#12230
     (http://bugs.mysql.com/12230))

   * Don't increase timeout for failover/reconnect.  (Bug#6577
     (http://bugs.mysql.com/6577))

   * Fixed client-side prepared statement bug with embedded `?'
     characters inside quoted identifiers (it was recognized as a
     placeholder, when it was not).

   * Don't allow `executeBatch()' for `CallableStatements' with
     registered `OUT'/`INOUT' parameters (JDBC compliance).

   * Fall back to platform-encoding for `URLDecoder.decode()' when
     parsing driver URL properties if the platform doesn't have a
     two-argument version of this method.


File: manual.info,  Node: cj-news-3-1-11,  Next: cj-news-3-1-10,  Prev: cj-news-3-1-12,  Up: cg-news-3-1

C.5.3.5 Changes in MySQL Connector/J 3.1.11 (07 October 2005)
.............................................................

Bugs fixed:

   * The configuration property `sessionVariables' now allows you to
     specify variables that start with the ``@'' sign.  (Bug#13453
     (http://bugs.mysql.com/13453))

   * URL configuration parameters don't allow ``&'' or ``='' in their
     values. The JDBC driver now parses configuration parameters as if
     they are encoded using the application/x-www-form-urlencoded
     format as specified by `java.net.URLDecoder'
     (`http://java.sun.com/j2se/1.5.0/docs/api/java/net/URLDecoder.html').

     If the ``%'' character is present in a configuration property, it
     must now be represented as `%25', which is the encoded form of
     ``%'' when using application/x-www-form-urlencoded encoding.
     (Bug#13453 (http://bugs.mysql.com/13453))

   * Workaround for Bug#13374 (http://bugs.mysql.com/13374):
     `ResultSet.getStatement()' on closed result set returns `NULL' (as
     per JDBC 4.0 spec, but not backward-compatible). Set the
     connection property `retainStatementAfterResultSetClose' to `true'
     to be able to retrieve a `ResultSet''s statement after the
     `ResultSet' has been closed via `.getStatement()' (the default is
     `false', to be JDBC-compliant and to reduce the chance that code
     using JDBC leaks `Statement' instances).  (Bug#13277
     (http://bugs.mysql.com/13277))

   * `ResultSetMetaData' from `Statement.getGeneratedKeys()' caused a
     `NullPointerException' to be thrown whenever a method that
     required a connection reference was called.  (Bug#13277
     (http://bugs.mysql.com/13277))

   * Backport of `VAR[BINARY|CHAR] [BINARY]' types detection from 5.0
     branch.  (Bug#13277 (http://bugs.mysql.com/13277))

   * Fixed `NullPointerException' when converting `catalog' parameter
     in many `DatabaseMetaDataMethods' to `byte[]'s (for the result
     set) when the parameter is `null'. (`null' isn't technically
     allowed by the JDBC specification, but we've historically allowed
     it).  (Bug#13277 (http://bugs.mysql.com/13277))

   * Backport of `Field' class,
     `ResultSetMetaData.getColumnClassName()', and
     `ResultSet.getObject(int)' changes from 5.0 branch to fix behavior
     surrounding `VARCHAR BINARY'/`VARBINARY' and related types.
     (Bug#13277 (http://bugs.mysql.com/13277))

   * Read response in `MysqlIO.sendFileToServer()', even if the local
     file can't be opened, otherwise next query issued will fail,
     because it's reading the response to the empty `LOAD DATA INFILE'
     packet sent to the server.  (Bug#13277
     (http://bugs.mysql.com/13277))

   * When `gatherPerfMetrics' is enabled for servers older than 4.1.0,
     a `NullPointerException' is thrown from the constructor of
     `ResultSet' if the query doesn't use any tables.  (Bug#13043
     (http://bugs.mysql.com/13043))

   * `java.sql.Types.OTHER' returned for `BINARY' and `VARBINARY'
     columns when using `DatabaseMetaData.getColumns()'.  (Bug#12970
     (http://bugs.mysql.com/12970))

   * `ServerPreparedStatement.getBinding()' now checks if the statement
     is closed before attempting to reference the list of parameter
     bindings, to avoid throwing a `NullPointerException'.  (Bug#12970
     (http://bugs.mysql.com/12970))

   * Tokenizer for `=' in URL properties was causing
     `sessionVariables=....' to be parameterized incorrectly.
     (Bug#12753 (http://bugs.mysql.com/12753))

   * `cp1251' incorrectly mapped to `win1251' for servers newer than
     4.0.x.  (Bug#12752 (http://bugs.mysql.com/12752))

   * `getExportedKeys()' (Bug#12541 (http://bugs.mysql.com/12541))

   * Specifying a catalog works as stated in the API docs.  (Bug#12541
     (http://bugs.mysql.com/12541))

   * Specifying `NULL' means that catalog will not be used to filter
     the results (thus all databases will be searched), unless you've
     set `nullCatalogMeansCurrent=true' in your JDBC URL properties.
     (Bug#12541 (http://bugs.mysql.com/12541))

   * `getIndexInfo()' (Bug#12541 (http://bugs.mysql.com/12541))

   * `getProcedures()' (and thus indirectly `getProcedureColumns()')
     (Bug#12541 (http://bugs.mysql.com/12541))

   * `getImportedKeys()' (Bug#12541 (http://bugs.mysql.com/12541))

   * Specifying `""' means `current' catalog, even though this isn't
     quite JDBC spec compliant, it's there for legacy users.
     (Bug#12541 (http://bugs.mysql.com/12541))

   * `getCrossReference()' (Bug#12541 (http://bugs.mysql.com/12541))

   * Added `Connection.isMasterConnection()' for clients to be able to
     determine if a multi-host master/slave connection is connected to
     the first host in the list.  (Bug#12541
     (http://bugs.mysql.com/12541))

   * `getColumns()' (Bug#12541 (http://bugs.mysql.com/12541))

   * Handling of catalog argument in `DatabaseMetaData.getIndexInfo()',
     which also means changes to the following methods in
     `DatabaseMetaData':

        * `getBestRowIdentifier()'

        * `getColumns()'

        * `getCrossReference()'

        * `getExportedKeys()'

        * `getImportedKeys()'

        * `getIndexInfo()'

        * `getPrimaryKeys()'

        * `getProcedures()' (and thus indirectly
          `getProcedureColumns()')

        * `getTables()'

     The `catalog' argument in all of these methods now behaves in the
     following way:

        * Specifying `NULL' means that catalog will not be used to
          filter the results (thus all databases will be searched),
          unless you've set `nullCatalogMeansCurrent=true' in your JDBC
          URL properties.

        * Specifying `""' means `current' catalog, even though this
          isn't quite JDBC spec compliant, it's there for legacy users.

        * Specifying a catalog works as stated in the API docs.

        * Made `Connection.clientPrepare()' available from `wrapped'
          connections in the `jdbc2.optional' package (connections built
          by `ConnectionPoolDataSource' instances).

     (Bug#12541 (http://bugs.mysql.com/12541))

   * `getBestRowIdentifier()' (Bug#12541 (http://bugs.mysql.com/12541))

   * Made `Connection.clientPrepare()' available from `wrapped'
     connections in the `jdbc2.optional' package (connections built by
     `ConnectionPoolDataSource' instances).  (Bug#12541
     (http://bugs.mysql.com/12541))

   * `getTables()' (Bug#12541 (http://bugs.mysql.com/12541))

   * `getPrimaryKeys()' (Bug#12541 (http://bugs.mysql.com/12541))

   * `Connection.prepareCall()' is database name case-sensitive (on
     Windows systems).  (Bug#12417 (http://bugs.mysql.com/12417))

   * `explainSlowQueries' hangs with server-side prepared statements.
     (Bug#12229 (http://bugs.mysql.com/12229))

   * Properties shared between master and slave with replication
     connection.  (Bug#12218 (http://bugs.mysql.com/12218))

   * Geometry types not handled with server-side prepared statements.
     (Bug#12104 (http://bugs.mysql.com/12104))

   * `maxPerformance.properties' mis-spells `elideSetAutoCommits'.
     (Bug#11976 (http://bugs.mysql.com/11976))

   * `ReplicationConnection' won't switch to slave, throws `Catalog
     can't be null' exception.  (Bug#11879
     (http://bugs.mysql.com/11879))

   * `Pstmt.setObject(...., Types.BOOLEAN)' throws exception.
     (Bug#11798 (http://bugs.mysql.com/11798))

   * Escape tokenizer doesn't respect stacked single quotes for escapes.
     (Bug#11797 (http://bugs.mysql.com/11797))

   * `GEOMETRY' type not recognized when using server-side prepared
     statements.  (Bug#11797 (http://bugs.mysql.com/11797))

   * Foreign key information that is quoted is parsed incorrectly when
     `DatabaseMetaData' methods use that information.  (Bug#11781
     (http://bugs.mysql.com/11781))

   * The `sendBlobChunkSize' property is now clamped to
     `max_allowed_packet' with consideration of stream buffer size and
     packet headers to avoid `PacketTooBigExceptions' when
     `max_allowed_packet' is similar in size to the default
     `sendBlobChunkSize' which is 1M.  (Bug#11781
     (http://bugs.mysql.com/11781))

   * `CallableStatement.clearParameters()' now clears resources
     associated with `INOUT'/`OUTPUT' parameters as well as `INPUT'
     parameters.  (Bug#11781 (http://bugs.mysql.com/11781))

   * Fixed regression caused by fix for Bug#11552
     (http://bugs.mysql.com/11552) that caused driver to return
     incorrect values for unsigned integers when those integers where
     within the range of the positive signed type.  (Bug#11663
     (http://bugs.mysql.com/11663))

   * Moved source code to Subversion repository.  (Bug#11663
     (http://bugs.mysql.com/11663))

   * Incorrect generation of testcase scripts for server-side prepared
     statements.  (Bug#11663 (http://bugs.mysql.com/11663))

   * Fixed statements generated for testcases missing `;' for `plain'
     statements.  (Bug#11629 (http://bugs.mysql.com/11629))

   * Spurious `!' on console when character encoding is `utf8'.
     (Bug#11629 (http://bugs.mysql.com/11629))

   * `StringUtils.getBytes()' doesn't work when using multi-byte
     character encodings and a length in _characters_ is specified.
     (Bug#11614 (http://bugs.mysql.com/11614))

   * `DBMD.storesLower/Mixed/UpperIdentifiers()' reports incorrect
     values for servers deployed on Windows.  (Bug#11575
     (http://bugs.mysql.com/11575))

   * Reworked `Field' class, `*Buffer', and `MysqlIO' to be aware of
     field lengths > `Integer.MAX_VALUE'.  (Bug#11498
     (http://bugs.mysql.com/11498))

   * Escape processor didn't honor strings demarcated with double
     quotes.  (Bug#11498 (http://bugs.mysql.com/11498))

   * Updated `DBMD.supportsCorrelatedQueries()' to return `true' for
     versions > 4.1, `supportsGroupByUnrelated()' to return `true' and
     `getResultSetHoldability()' to return `HOLD_CURSORS_OVER_COMMIT'.
     (Bug#11498 (http://bugs.mysql.com/11498))

   * Lifted restriction of changing streaming parameters with
     server-side prepared statements. As long as `all' streaming
     parameters were set before execution, `.clearParameters()' does
     not have to be called. (due to limitation of client/server
     protocol, prepared statements can not reset _individual_ stream
     data on the server side).  (Bug#11498
     (http://bugs.mysql.com/11498))

   * `ResultSet.moveToCurrentRow()' fails to work when preceded by a
     call to `ResultSet.moveToInsertRow()'.  (Bug#11190
     (http://bugs.mysql.com/11190))

   * `VARBINARY' data corrupted when using server-side prepared
     statements and `.setBytes()'.  (Bug#11115
     (http://bugs.mysql.com/11115))

   * `Statement.getWarnings()' fails with NPE if statement has been
     closed.  (Bug#10630 (http://bugs.mysql.com/10630))

   * Only get `char[]' from SQL in `PreparedStatement.ParseInfo()' when
     needed.  (Bug#10630 (http://bugs.mysql.com/10630))


File: manual.info,  Node: cj-news-3-1-10,  Next: cj-news-3-1-9,  Prev: cj-news-3-1-11,  Up: cg-news-3-1

C.5.3.6 Changes in MySQL Connector/J 3.1.10 (23 June 2005)
..........................................................

Bugs fixed:

   * Initial implemention of `ParameterMetadata' for
     `PreparedStatement.getParameterMetadata()'.  Only works fully for
     `CallableStatements', as current server-side prepared statements
     return every parameter as a `VARCHAR' type.

   * Fixed connecting without a database specified raised an exception
     in `MysqlIO.changeDatabaseTo()'.


File: manual.info,  Node: cj-news-3-1-9,  Next: cj-news-3-1-8,  Prev: cj-news-3-1-10,  Up: cg-news-3-1

C.5.3.7 Changes in MySQL Connector/J 3.1.9 (22 June 2005)
.........................................................

Bugs fixed:

   * Production package doesn't include JBoss integration classes.
     (Bug#11411 (http://bugs.mysql.com/11411))

   * Removed nonsensical `costly type conversion' warnings when using
     usage advisor.  (Bug#11411 (http://bugs.mysql.com/11411))

   * Fixed `PreparedStatement.setClob()' not accepting `null' as a
     parameter.  (Bug#11360 (http://bugs.mysql.com/11360))

   * Connector/J dumping query into `SQLException' twice.  (Bug#11360
     (http://bugs.mysql.com/11360))

   * `autoReconnect' ping causes exception on connection startup.
     (Bug#11259 (http://bugs.mysql.com/11259))

   * `Connection.setCatalog()' is now aware of the
     `useLocalSessionState' configuration property, which when set to
     `true' will prevent the driver from sending `USE ...' to the
     server if the requested catalog is the same as the current catalog.
     (Bug#11115 (http://bugs.mysql.com/11115))

   * `3-0-Compat' -- Compatibility with Connector/J 3.0.x functionality
     (Bug#11115 (http://bugs.mysql.com/11115))

   * `maxPerformance' -- maximum performance without being reckless
     (Bug#11115 (http://bugs.mysql.com/11115))

   * `solarisMaxPerformance' -- maximum performance for Solaris, avoids
     syscalls where it can (Bug#11115 (http://bugs.mysql.com/11115))

   * Added `maintainTimeStats' configuration property (defaults to
     `true'), which tells the driver whether or not to keep track of
     the last query time and the last successful packet sent to the
     server's time. If set to `false', removes two syscalls per query.
     (Bug#11115 (http://bugs.mysql.com/11115))

   * `VARBINARY' data corrupted when using server-side prepared
     statements and `ResultSet.getBytes()'.  (Bug#11115
     (http://bugs.mysql.com/11115))

   * Added the following configuration bundles, use one or many via the
     `useConfigs' configuration property:

        * `maxPerformance' -- maximum performance without being reckless

        * `solarisMaxPerformance' -- maximum performance for Solaris,
          avoids syscalls where it can

        * `3-0-Compat' -- Compatibility with Connector/J 3.0.x
          functionality

     (Bug#11115 (http://bugs.mysql.com/11115))

   * Try to handle `OutOfMemoryErrors' more gracefully. Although not
     much can be done, they will in most cases close the connection
     they happened on so that further operations don't run into a
     connection in some unknown state.  When an OOM has happened, any
     further operations on the connection will fail with a `Connection
     closed' exception that will also list the OOM exception as the
     reason for the implicit connection close event.  (Bug#10850
     (http://bugs.mysql.com/10850))

   * Setting `cachePrepStmts=true' now causes the `Connection' to also
     cache the check the driver performs to determine if a prepared
     statement can be server-side or not, as well as caches server-side
     prepared statements for the lifetime of a connection. As before,
     the `prepStmtCacheSize' parameter controls the size of these
     caches.  (Bug#10850 (http://bugs.mysql.com/10850))

   * Don't send `COM_RESET_STMT' for each execution of a server-side
     prepared statement if it isn't required.  (Bug#10850
     (http://bugs.mysql.com/10850))

   * 0-length streams not sent to server when using server-side
     prepared statements.  (Bug#10850 (http://bugs.mysql.com/10850))

   * Driver detects if you're running MySQL-5.0.7 or later, and does
     not scan for `LIMIT ?[,?]' in statements being prepared, as the
     server supports those types of queries now.  (Bug#10850
     (http://bugs.mysql.com/10850))

   * Reorganized directory layout. Sources now are in `src' folder.
     Don't pollute parent directory when building, now output goes to
     `./build', distribution goes to `./dist'.  (Bug#10496
     (http://bugs.mysql.com/10496))

   * Added support/bug hunting feature that generates `.sql' test
     scripts to `STDERR' when `autoGenerateTestcaseScript' is set to
     `true'.  (Bug#10496 (http://bugs.mysql.com/10496))

   * `SQLException' is thrown when using property `characterSetResults'
     with `cp932' or `eucjpms'.  (Bug#10496
     (http://bugs.mysql.com/10496))

   * The datatype returned for `TINYINT(1)' columns when
     `tinyInt1isBit=true' (the default) can be switched between
     `Types.BOOLEAN' and `Types.BIT' using the new configuration
     property `transformedBitIsBoolean', which defaults to `false'. If
     set to `false' (the default), `DatabaseMetaData.getColumns()' and
     `ResultSetMetaData.getColumnType()' will return `Types.BOOLEAN' for
     `TINYINT(1)' columns. If `true', `Types.BOOLEAN' will be returned
     instead. Regardless of this configuration property, if
     `tinyInt1isBit' is enabled, columns with the type `TINYINT(1)'
     will be returned as `java.lang.Boolean' instances from
     `ResultSet.getObject(...)', and
     `ResultSetMetaData.getColumnClassName()' will return
     `java.lang.Boolean'.  (Bug#10485 (http://bugs.mysql.com/10485))

   * `SQLException' thrown when retrieving `YEAR(2)' with
     `ResultSet.getString()'. The driver will now always treat `YEAR'
     types as `java.sql.Dates' and return the correct values for
     `getString()'. Alternatively, the `yearIsDateType' connection
     property can be set to `false' and the values will be treated as
     `SHORT's.  (Bug#10485 (http://bugs.mysql.com/10485))

   * Driver doesn't support `{?=CALL(...)}' for calling stored
     functions. This involved adding support for function retrieval to
     `DatabaseMetaData.getProcedures()' and `getProcedureColumns()' as
     well.  (Bug#10310 (http://bugs.mysql.com/10310))

   * Unsigned `SMALLINT' treated as signed for `ResultSet.getInt()',
     fixed all cases for `UNSIGNED' integer values and server-side
     prepared statements, as well as `ResultSet.getObject()' for
     `UNSIGNED TINYINT'.  (Bug#10156 (http://bugs.mysql.com/10156))

   * Made `ServerPreparedStatement.asSql()' work correctly so
     auto-explain functionality would work with server-side prepared
     statements.  (Bug#10155 (http://bugs.mysql.com/10155))

   * Double quotes not recognized when parsing client-side prepared
     statements.  (Bug#10155 (http://bugs.mysql.com/10155))

   * Made JDBC2-compliant wrappers public in order to allow access to
     vendor extensions.  (Bug#10155 (http://bugs.mysql.com/10155))

   * `DatabaseMetaData.supportsMultipleOpenResults()' now returns
     `true'. The driver has supported this for some time, DBMD just
     missed that fact.  (Bug#10155 (http://bugs.mysql.com/10155))

   * Cleaned up logging of profiler events, moved code to dump a
     profiler event as a string to `com.mysql.jdbc.log.LogUtils' so
     that third parties can use it.  (Bug#10155
     (http://bugs.mysql.com/10155))

   * Made `enableStreamingResults()' visible on
     `com.mysql.jdbc.jdbc2.optional.StatementWrapper'.  (Bug#10155
     (http://bugs.mysql.com/10155))

   * Actually write manifest file to correct place so it ends up in the
     binary jar file.  (Bug#10144 (http://bugs.mysql.com/10144))

   * Added `createDatabaseIfNotExist' property (default is `false'),
     which will cause the driver to ask the server to create the
     database specified in the URL if it doesn't exist. You must have
     the appropriate privileges for database creation for this to work.
     (Bug#10144 (http://bugs.mysql.com/10144))

   * Memory leak in `ServerPreparedStatement' if `serverPrepare()'
     fails.  (Bug#10144 (http://bugs.mysql.com/10144))

   * `com.mysql.jdbc.PreparedStatement.ParseInfo' does unnecessary call
     to `toCharArray()'.  (Bug#9064 (http://bugs.mysql.com/9064))

   * Driver now correctly uses CP932 if available on the server for
     Windows-31J, CP932 and MS932 java encoding names, otherwise it
     resorts to SJIS, which is only a close approximation. Currently
     only MySQL-5.0.3 and newer (and MySQL-4.1.12 or .13, depending on
     when the character set gets backported) can reliably support any
     variant of CP932.

   * Overhaul of character set configuration, everything now lives in a
     properties file.


File: manual.info,  Node: cj-news-3-1-8,  Next: cj-news-3-1-7,  Prev: cj-news-3-1-9,  Up: cg-news-3-1

C.5.3.8 Changes in MySQL Connector/J 3.1.8 (14 April 2005)
..........................................................

Bugs fixed:

   * Should accept `null' for catalog (meaning use current) in DBMD
     methods, even though it's not JDBC-compliant for legacy's sake.
     Disable by setting connection property `nullCatalogMeansCurrent' to
     `false' (which will be the default value in C/J 3.2.x).  (Bug#9917
     (http://bugs.mysql.com/9917))

   * Fixed driver not returning `true' for `-1' when
     `ResultSet.getBoolean()' was called on result sets returned from
     server-side prepared statements.  (Bug#9778
     (http://bugs.mysql.com/9778))

   * Added a `Manifest.MF' file with implementation information to the
     `.jar' file.  (Bug#9778 (http://bugs.mysql.com/9778))

   * More tests in `Field.isOpaqueBinary()' to distinguish opaque
     binary (that is, fields with type `CHAR(n)' and `CHARACTER SET
     BINARY') from output of various scalar and aggregate functions
     that return strings.  (Bug#9778 (http://bugs.mysql.com/9778))

   * `DBMD.getTables()' shouldn't return tables if views are asked for,
     even if the database version doesn't support views.  (Bug#9778
     (http://bugs.mysql.com/9778))

   * Should accept `null' for name patterns in DBMD (meaning ``%''),
     even though it isn't JDBC compliant, for legacy's sake. Disable by
     setting connection property `nullNamePatternMatchesAll' to `false'
     (which will be the default value in C/J 3.2.x).  (Bug#9769
     (http://bugs.mysql.com/9769))

   * Then fallback to our `STDERR' logging.  (Bug#9704
     (http://bugs.mysql.com/9704))

   * The performance metrics feature now gathers information about
     number of tables referenced in a SELECT.  (Bug#9704
     (http://bugs.mysql.com/9704))

   * The logging system is now automatically configured. If the value
     has been set by the user, via the URL property `logger' or the
     system property `com.mysql.jdbc.logger', then use that, otherwise,
     autodetect it using the following steps:

       1. Log4j, if it's available,

       2. Then JDK1.4 logging,

       3. Then fallback to our `STDERR' logging.

     (Bug#9704 (http://bugs.mysql.com/9704))

   * Then JDK1.4 logging, (Bug#9704 (http://bugs.mysql.com/9704))

   * Log4j, if it's available, (Bug#9704 (http://bugs.mysql.com/9704))

   * `Statement.getMoreResults()' could throw NPE when existing result
     set was `.close()'d.  (Bug#9704 (http://bugs.mysql.com/9704))

   * Stored procedures with `DECIMAL' parameters with storage
     specifications that contained ``,'' in them would fail.  (Bug#9682
     (http://bugs.mysql.com/9682))

   * `PreparedStatement.setObject(int, Object, int type, int scale)'
     now uses scale value for `BigDecimal' instances.  (Bug#9682
     (http://bugs.mysql.com/9682))

   * Added support for the c3p0 connection pool's
     (`http://c3p0.sf.net/') validation/connection checker interface
     which uses the lightweight `COM_PING' call to the server if
     available. To use it, configure your c3p0 connection pool's
     `connectionTesterClassName' property to use
     `com.mysql.jdbc.integration.c3p0.MysqlConnectionTester'.
     (Bug#9320 (http://bugs.mysql.com/9320))

   * `PreparedStatement.getMetaData()' inserts blank row in database
     under certain conditions when not using server-side prepared
     statements.  (Bug#9320 (http://bugs.mysql.com/9320))

   * Better detection of `LIMIT' inside/outside of quoted strings so
     that the driver can more correctly determine whether a prepared
     statement can be prepared on the server or not.  (Bug#9320
     (http://bugs.mysql.com/9320))

   * `Connection.canHandleAsPreparedStatement()' now makes `best
     effort' to distinguish `LIMIT' clauses with placeholders in them
     from ones without in order to have fewer false positives when
     generating work-arounds for statements the server cannot currently
     handle as server-side prepared statements.  (Bug#9320
     (http://bugs.mysql.com/9320))

   * Fixed `build.xml' to not compile `log4j' logging if `log4j' not
     available.  (Bug#9320 (http://bugs.mysql.com/9320))

   * Added finalizers to `ResultSet' and `Statement' implementations to
     be JDBC spec-compliant, which requires that if not explicitly
     closed, these resources should be closed upon garbage collection.
     (Bug#9319 (http://bugs.mysql.com/9319))

   * Stored procedures with same name in different databases confuse
     the driver when it tries to determine parameter counts/types.
     (Bug#9319 (http://bugs.mysql.com/9319))

   * A continuation of Bug#8868 (http://bugs.mysql.com/8868), where
     functions used in queries that should return non-string types when
     resolved by temporary tables suddenly become opaque binary strings
     (work-around for server limitation). Also fixed fields with type of
     `CHAR(n) CHARACTER SET BINARY' to return correct/matching classes
     for `RSMD.getColumnClassName()' and `ResultSet.getObject()'.
     (Bug#9236 (http://bugs.mysql.com/9236))

   * Cannot use `UTF-8' for characterSetResults configuration property.
     (Bug#9206 (http://bugs.mysql.com/9206))

   * `PreparedStatement.addBatch()' doesn't work with server-side
     prepared statements and streaming `BINARY' data.  (Bug#9040
     (http://bugs.mysql.com/9040))

   * `ServerPreparedStatements' now correctly `stream' `BLOB'/`CLOB'
     data to the server. You can configure the threshold chunk size
     using the JDBC URL property `blobSendChunkSize' (the default is
     1MB).  (Bug#8868 (http://bugs.mysql.com/8868))

   * `DATE_FORMAT()' queries returned as `BLOB's from `getObject()'.
     (Bug#8868 (http://bugs.mysql.com/8868))

   * Server-side session variables can be preset at connection time by
     passing them as a comma-delimited list for the connection property
     `sessionVariables'.  (Bug#8868 (http://bugs.mysql.com/8868))

   * `BlobFromLocator' now uses correct identifier quoting when
     generating prepared statements.  (Bug#8868
     (http://bugs.mysql.com/8868))

   * Fixed regression in `ping()' for users using `autoReconnect=true'.
     (Bug#8868 (http://bugs.mysql.com/8868))

   * Check for empty strings (`''') when converting `CHAR'/`VARCHAR'
     column data to numbers, throw exception if
     `emptyStringsConvertToZero' configuration property is set to
     `false' (for backward-compatibility with 3.0, it is now set to
     `true' by default, but will most likely default to `false' in 3.2).
     (Bug#8803 (http://bugs.mysql.com/8803))

   * `DATA_TYPE' column from `DBMD.getBestRowIdentifier()' causes
     `ArrayIndexOutOfBoundsException' when accessed (and in fact,
     didn't return any value).  (Bug#8803 (http://bugs.mysql.com/8803))

   * `DBMD.supportsMixedCase*Identifiers()' returns wrong value on
     servers running on case-sensitive filesystems.  (Bug#8800
     (http://bugs.mysql.com/8800))

   * `DBMD.supportsResultSetConcurrency()' not returning `true' for
     forward-only/read-only result sets (we obviously support this).
     (Bug#8792 (http://bugs.mysql.com/8792))

   * Fixed `ResultSet.getTime()' on a `NULL' value for server-side
     prepared statements throws NPE.

   * Made `Connection.ping()' a public method.

   * Added support for new precision-math `DECIMAL' type in MySQL 5.0.3
     and up.

   * Fixed `DatabaseMetaData.getTables()' returning views when they
     were not asked for as one of the requested table types.


File: manual.info,  Node: cj-news-3-1-7,  Next: cj-news-3-1-6,  Prev: cj-news-3-1-8,  Up: cg-news-3-1

C.5.3.9 Changes in MySQL Connector/J 3.1.7 (18 February 2005)
.............................................................

Bugs fixed:

   * `PreparedStatements' not creating streaming result sets.
     (Bug#8487 (http://bugs.mysql.com/8487))

   * Don't pass `NULL' to `String.valueOf()' in
     `ResultSet.getNativeConvertToString()', as it stringifies it (that
     is, returns `null'), which is not correct for the method in
     question.  (Bug#8487 (http://bugs.mysql.com/8487))

   * Fixed NPE in `ResultSet.realClose()' when using usage advisor and
     result set was already closed.  (Bug#8428
     (http://bugs.mysql.com/8428))

   * `ResultSet.getString()' doesn't maintain format stored on server,
     bug fix only enabled when `noDatetimeStringSync' property is set to
     `true' (the default is `false').  (Bug#8428
     (http://bugs.mysql.com/8428))

   * Added support for `BIT' type in MySQL-5.0.3.  The driver will
     treat `BIT(1-8)' as the JDBC standard `BIT' type (which maps to
     `java.lang.Boolean'), as the server does not currently send enough
     information to determine the size of a bitfield when < 9 bits are
     declared.  `BIT(>9)' will be treated as `VARBINARY', and will
     return `byte[]' when `getObject()' is called.  (Bug#8424
     (http://bugs.mysql.com/8424))

   * Added `useLocalSessionState' configuration property, when set to
     `true' the JDBC driver trusts that the application is well-behaved
     and only sets autocommit and transaction isolation levels using
     the methods provided on `java.sql.Connection', and therefore can
     manipulate these values in many cases without incurring
     round-trips to the database server.  (Bug#8424
     (http://bugs.mysql.com/8424))

   * Added `enableStreamingResults()' to `Statement' for connection
     pool implementations that check `Statement.setFetchSize()' for
     specification-compliant values. Call `Statement.setFetchSize(>=0)'
     to disable the streaming results for that statement.  (Bug#8424
     (http://bugs.mysql.com/8424))

   * `ResultSet.getBigDecimal()' throws exception when rounding would
     need to occur to set scale. The driver now chooses a rounding mode
     of `half up' if non-rounding `BigDecimal.setScale()' fails.
     (Bug#8424 (http://bugs.mysql.com/8424))

   * Fixed synchronization issue with
     `ServerPreparedStatement.serverPrepare()' that could cause
     deadlocks/crashes if connection was shared between threads.
     (Bug#8096 (http://bugs.mysql.com/8096))

   * Emulated locators corrupt binary data when using server-side
     prepared statements.  (Bug#8096 (http://bugs.mysql.com/8096))

   * Infinite recursion when `falling back' to master in failover
     configuration.  (Bug#7952 (http://bugs.mysql.com/7952))

   * Disable multi-statements (if enabled) for MySQL-4.1 versions prior
     to version 4.1.10 if the query cache is enabled, as the server
     returns wrong results in this configuration.  (Bug#7952
     (http://bugs.mysql.com/7952))

   * Removed `dontUnpackBinaryResults' functionality, the driver now
     always stores results from server-side prepared statements as is
     from the server and unpacks them on demand.  (Bug#7952
     (http://bugs.mysql.com/7952))

   * Fixed duplicated code in `configureClientCharset()' that prevented
     `useOldUTF8Behavior=true' from working properly.  (Bug#7952
     (http://bugs.mysql.com/7952))

   * Added `holdResultsOpenOverStatementClose' property (default is
     `false'), that keeps result sets open over statement.close() or
     new execution on same statement (suggested by Kevin Burton).
     (Bug#7715 (http://bugs.mysql.com/7715))

   * Detect new `sql_mode' variable in string form (it used to be
     integer) and adjust quoting method for strings appropriately.
     (Bug#7715 (http://bugs.mysql.com/7715))

   * Timestamps converted incorrectly to strings with server-side
     prepared statements and updatable result sets.  (Bug#7715
     (http://bugs.mysql.com/7715))

   * Timestamp key column data needed `_binary' stripped for
     `UpdatableResultSet.refreshRow()'.  (Bug#7686
     (http://bugs.mysql.com/7686))

   * Choose correct `direction' to apply time adjustments when both
     client and server are in GMT time zone when using
     `ResultSet.get(..., cal)' and `PreparedStatement.set(...., cal)'.
     (Bug#4718 (http://bugs.mysql.com/4718))

   * Remove `_binary' introducer from parameters used as in/out
     parameters in `CallableStatement'.  (Bug#4718
     (http://bugs.mysql.com/4718))

   * Always return `byte[]'s for output parameters registered as
     `*BINARY'.  (Bug#4718 (http://bugs.mysql.com/4718))

   * By default, the driver now scans SQL you are preparing via all
     variants of `Connection.prepareStatement()' to determine if it is
     a supported type of statement to prepare on the server side, and
     if it is not supported by the server, it instead prepares it as a
     client-side emulated prepared statement. You can disable this by
     passing `emulateUnsupportedPstmts=false' in your JDBC URL.
     (Bug#4718 (http://bugs.mysql.com/4718))

   * Added `dontTrackOpenResources' option (default is `false', to be
     JDBC compliant), which helps with memory use for non-well-behaved
     apps (that is, applications that don't close `Statement' objects
     when they should).  (Bug#4718 (http://bugs.mysql.com/4718))

   * Send correct value for `boolean' `true' to server for
     `PreparedStatement.setObject(n, "true", Types.BIT)'.  (Bug#4718
     (http://bugs.mysql.com/4718))

   * Fixed bug with Connection not caching statements from
     `prepareStatement()' when the statement wasn't a server-side
     prepared statement.  (Bug#4718 (http://bugs.mysql.com/4718))


File: manual.info,  Node: cj-news-3-1-6,  Next: cj-news-3-1-5,  Prev: cj-news-3-1-7,  Up: cg-news-3-1

C.5.3.10 Changes in MySQL Connector/J 3.1.6 (23 December 2004)
..............................................................

Bugs fixed:

   * `DBMD.getProcedures()' doesn't respect catalog parameter.
     (Bug#7026 (http://bugs.mysql.com/7026))

   * Fixed hang on `SocketInputStream.read()' with
     `Statement.setMaxRows()' and multiple result sets when driver has
     to truncate result set directly, rather than tacking a `LIMIT N'
     on the end of it.


File: manual.info,  Node: cj-news-3-1-5,  Next: cj-news-3-1-4,  Prev: cj-news-3-1-6,  Up: cg-news-3-1

C.5.3.11 Changes in MySQL Connector/J 3.1.5 (02 December 2004)
..............................................................

Bugs fixed:

   * Use 1MB packet for sending file for `LOAD DATA LOCAL INFILE' if
     that is < `max_allowed_packet' on server.  (Bug#6537
     (http://bugs.mysql.com/6537))

   * `SUM()' on `DECIMAL' with server-side prepared statement ignores
     scale if zero-padding is needed (this ends up being due to
     conversion to `DOUBLE' by server, which when converted to a string
     to parse into `BigDecimal', loses all `padding' zeros).  (Bug#6537
     (http://bugs.mysql.com/6537))

   * Use `DatabaseMetaData.getIdentifierQuoteString()' when building
     DBMD queries.  (Bug#6537 (http://bugs.mysql.com/6537))

   * Use our own implementation of buffered input streams to get around
     blocking behavior of `java.io.BufferedInputStream'. Disable this
     with `useReadAheadInput=false'.  (Bug#6399
     (http://bugs.mysql.com/6399))

   * Make auto-deserialization of `java.lang.Objects' stored in `BLOB'
     columns configurable via `autoDeserialize' property (defaults to
     `false').  (Bug#6399 (http://bugs.mysql.com/6399))

   * `ResultSetMetaData.getColumnDisplaySize()' returns incorrect
     values for multi-byte charsets.  (Bug#6399
     (http://bugs.mysql.com/6399))

   * Re-work `Field.isOpaqueBinary()' to detect `CHAR(N) CHARACTER SET
     BINARY' to support fixed-length binary fields for
     `ResultSet.getObject()'.  (Bug#6399 (http://bugs.mysql.com/6399))

   * Failing to connect to the server when one of the addresses for the
     given host name is IPV6 (which the server does not yet bind on).
     The driver now loops through _all_ IP addresses for a given host,
     and stops on the first one that `accepts()' a `socket.connect()'.
     (Bug#6348 (http://bugs.mysql.com/6348))

   * Removed unwanted new `Throwable()' in `ResultSet' constructor due
     to bad merge (caused a new object instance that was never used for
     every result set created). Found while profiling for Bug#6359
     (http://bugs.mysql.com/6359).  (Bug#6225
     (http://bugs.mysql.com/6225))

   * `ServerSidePreparedStatement' allocating short-lived objects
     unnecessarily.  (Bug#6225 (http://bugs.mysql.com/6225))

   * Use null-safe-equals for key comparisons in updatable result sets.
     (Bug#6225 (http://bugs.mysql.com/6225))

   * Fixed too-early creation of `StringBuffer' in
     `EscapeProcessor.escapeSQL()', also return `String' when escaping
     not needed (to avoid unnecessary object allocations). Found while
     profiling for Bug#6359 (http://bugs.mysql.com/6359).  (Bug#6225
     (http://bugs.mysql.com/6225))

   * `UNSIGNED BIGINT' unpacked incorrectly from server-side prepared
     statement result sets.  (Bug#5729 (http://bugs.mysql.com/5729))

   * Added experimental configuration property
     `dontUnpackBinaryResults', which delays unpacking binary result
     set values until they're asked for, and only creates object
     instances for non-numerical values (it is set to `false' by
     default). For some usecase/jvm combinations, this is friendlier on
     the garbage collector.  (Bug#5706 (http://bugs.mysql.com/5706))

   * Don't throw exceptions for `Connection.releaseSavepoint()'.
     (Bug#5706 (http://bugs.mysql.com/5706))

   * Inefficient detection of pre-existing string instances in
     `ResultSet.getNativeString()'.  (Bug#5706
     (http://bugs.mysql.com/5706))

   * Use a per-session `Calendar' instance by default when decoding
     dates from `ServerPreparedStatements' (set to old, less performant
     behavior by setting property `dynamicCalendars=true').  (Bug#5706
     (http://bugs.mysql.com/5706))

   * Fixed batched updates with server prepared statements weren't
     looking if the types had changed for a given batched set of
     parameters compared to the previous set, causing the server to
     return the error `Wrong arguments to mysql_stmt_execute()'.
     (Bug#5235 (http://bugs.mysql.com/5235))

   * Handle case when string representation of timestamp contains
     trailing ``.'' with no numbers following it.  (Bug#5235
     (http://bugs.mysql.com/5235))

   * Server-side prepared statements did not honor
     `zeroDateTimeBehavior' property, and would cause class-cast
     exceptions when using `ResultSet.getObject()', as the all-zero
     string was always returned.  (Bug#5235
     (http://bugs.mysql.com/5235))

   * Fix comparisons made between string constants and dynamic strings
     that are converted with either `toUpperCase()' or `toLowerCase()'
     to use `Locale.ENGLISH', as some locales `override' case rules for
     English. Also use `StringUtils.indexOfIgnoreCase()' instead of
     `.toUpperCase().indexOf()', avoids creating a very short-lived
     transient `String' instance.


File: manual.info,  Node: cj-news-3-1-4,  Next: cj-news-3-1-3,  Prev: cj-news-3-1-5,  Up: cg-news-3-1

C.5.3.12 Changes in MySQL Connector/J 3.1.4 (04 September 2004)
...............................................................

Bugs fixed:

   * Fixed `ServerPreparedStatement' to read prepared statement
     metadata off the wire, even though it's currently a placeholder
     instead of using `MysqlIO.clearInputStream()' which didn't work at
     various times because data wasn't available to read from the
     server yet. This fixes sporadic errors users were having with
     `ServerPreparedStatements' throwing
     `ArrayIndexOutOfBoundExceptions'.  (Bug#5032
     (http://bugs.mysql.com/5032))

   * Added three ways to deal with all-zero datetimes when reading them
     from a `ResultSet': `exception' (the default), which throws an
     `SQLException' with an SQLState of `S1009'; `convertToNull', which
     returns `NULL' instead of the date; and `round', which rounds the
     date to the nearest closest value which is `'0001-01-01''.
     (Bug#5032 (http://bugs.mysql.com/5032))

   * The driver is more strict about truncation of numerics on
     `ResultSet.get*()', and will throw an `SQLException' when
     truncation is detected. You can disable this by setting
     `jdbcCompliantTruncation' to `false' (it is enabled by default, as
     this functionality is required for JDBC compliance).  (Bug#5032
     (http://bugs.mysql.com/5032))

   * You can now use URLs in `LOAD DATA LOCAL INFILE' statements, and
     the driver will use Java's built-in handlers for retreiving the
     data and sending it to the server. This feature is not enabled by
     default, you must set the `allowUrlInLocalInfile' connection
     property to `true'.  (Bug#5032 (http://bugs.mysql.com/5032))

   * `ResultSet.getObject()' doesn't return type `Boolean' for
     pseudo-bit types from prepared statements on 4.1.x (shortcut for
     avoiding extra type conversion when using binary-encoded result
     sets obscured test in `getObject()' for `pseudo' bit type).
     (Bug#5032 (http://bugs.mysql.com/5032))

   * Use `com.mysql.jdbc.Message''s classloader when loading resource
     bundle, should fix sporadic issues when the caller's classloader
     can't locate the resource bundle.  (Bug#5032
     (http://bugs.mysql.com/5032))

   * `ServerPreparedStatements' dealing with return of `DECIMAL' type
     don't work.  (Bug#5012 (http://bugs.mysql.com/5012))

   * Track packet sequence numbers if `enablePacketDebug=true', and
     throw an exception if packets received out-of-order.  (Bug#4689
     (http://bugs.mysql.com/4689))

   * `ResultSet.wasNull()' does not work for primatives if a previous
     `null' was returned.  (Bug#4689 (http://bugs.mysql.com/4689))

   * Optimized integer number parsing, enable `old' slower integer
     parsing using JDK classes via `useFastIntParsing=false' property.
     (Bug#4642 (http://bugs.mysql.com/4642))

   * Added `useOnlyServerErrorMessages' property, which causes message
     text in exceptions generated by the server to only contain the
     text sent by the server (as opposed to the SQLState's `standard'
     description, followed by the server's error message). This
     property is set to `true' by default.  (Bug#4642
     (http://bugs.mysql.com/4642))

   * `ServerPreparedStatement.execute*()' sometimes threw
     `ArrayIndexOutOfBoundsException' when unpacking field metadata.
     (Bug#4642 (http://bugs.mysql.com/4642))

   * Connector/J 3.1.3 beta does not handle integers correctly (caused
     by changes to support unsigned reads in `Buffer.readInt()' ->
     `Buffer.readShort()').  (Bug#4510 (http://bugs.mysql.com/4510))

   * Added support in `DatabaseMetaData.getTables()' and
     `getTableTypes()' for views, which are now available in MySQL
     server 5.0.x.  (Bug#4510 (http://bugs.mysql.com/4510))

   * `ResultSet.getObject()' returns wrong type for strings when using
     prepared statements.  (Bug#4482 (http://bugs.mysql.com/4482))

   * Calling `MysqlPooledConnection.close()' twice (even though an
     application error), caused NPE. Fixed.  (Bug#4482
     (http://bugs.mysql.com/4482))


File: manual.info,  Node: cj-news-3-1-3,  Next: cj-news-3-1-2,  Prev: cj-news-3-1-4,  Up: cg-news-3-1

C.5.3.13 Changes in MySQL Connector/J 3.1.3 (07 July 2004)
..........................................................

Bugs fixed:

   * Support new time zone variables in MySQL-4.1.3 when
     `useTimezone=true'.  (Bug#4311 (http://bugs.mysql.com/4311))

   * Error in retrieval of `mediumint' column with prepared statements
     and binary protocol.  (Bug#4311 (http://bugs.mysql.com/4311))

   * Support for unsigned numerics as return types from prepared
     statements. This also causes a change in `ResultSet.getObject()'
     for the `bigint unsigned' type, which used to return `BigDecimal'
     instances, it now returns instances of `java.lang.BigInteger'.
     (Bug#4311 (http://bugs.mysql.com/4311))

   * Externalized more messages (on-going effort).  (Bug#4119
     (http://bugs.mysql.com/4119))

   * Null bitmask sent for server-side prepared statements was
     incorrect.  (Bug#4119 (http://bugs.mysql.com/4119))

   * Added constants for MySQL error numbers (publicly accessible, see
     `com.mysql.jdbc.MysqlErrorNumbers'), and the ability to generate
     the mappings of vendor error codes to SQLStates that the driver
     uses (for documentation purposes).  (Bug#4119
     (http://bugs.mysql.com/4119))

   * Added packet debuging code (see the `enablePacketDebug' property
     documentation).  (Bug#4119 (http://bugs.mysql.com/4119))

   * Use SQL Standard SQL states by default, unless `useSqlStateCodes'
     property is set to `false'.  (Bug#4119
     (http://bugs.mysql.com/4119))

   * Mangle output parameter names for `CallableStatements' so they
     will not clash with user variable names.

   * Added support for `INOUT' parameters in `CallableStatements'.


File: manual.info,  Node: cj-news-3-1-2,  Next: cj-news-3-1-1,  Prev: cj-news-3-1-3,  Up: cg-news-3-1

C.5.3.14 Changes in MySQL Connector/J 3.1.2 (09 June 2004)
..........................................................

Bugs fixed:

   * Don't enable server-side prepared statements for server version
     5.0.0 or 5.0.1, as they aren't compatible with the '4.1.2+' style
     that the driver uses (the driver expects information to come back
     that isn't there, so it hangs).  (Bug#3804
     (http://bugs.mysql.com/3804))

   * `getWarnings()' returns `SQLWarning' instead of `DataTruncation'.
     (Bug#3804 (http://bugs.mysql.com/3804))

   * `getProcedureColumns()' doesn't work with wildcards for procedure
     name.  (Bug#3540 (http://bugs.mysql.com/3540))

   * `getProcedures()' does not return any procedures in result set.
     (Bug#3539 (http://bugs.mysql.com/3539))

   * Fixed `DatabaseMetaData.getProcedures()' when run on MySQL-5.0.0
     (output of `SHOW PROCEDURE STATUS' changed between 5.0.0 and 5.0.1.
     (Bug#3520 (http://bugs.mysql.com/3520))

   * Added `connectionCollation' property to cause driver to issue `set
     collation_connection=...' query on connection init if default
     collation for given charset is not appropriate.  (Bug#3520
     (http://bugs.mysql.com/3520))

   * `DBMD.getSQLStateType()' returns incorrect value.  (Bug#3520
     (http://bugs.mysql.com/3520))

   * Correctly map output parameters to position given in
     `prepareCall()' versus. order implied during
     `registerOutParameter()'.  (Bug#3146 (http://bugs.mysql.com/3146))

   * Cleaned up detection of server properties.  (Bug#3146
     (http://bugs.mysql.com/3146))

   * Correctly detect initial character set for servers >= 4.1.0.
     (Bug#3146 (http://bugs.mysql.com/3146))

   * Support placeholder for parameter metadata for server >= 4.1.2.
     (Bug#3146 (http://bugs.mysql.com/3146))

   * Added `gatherPerformanceMetrics' property, along with properties
     to control when/where this info gets logged (see docs for more
     info).

   * Fixed case when no parameters could cause a `NullPointerException'
     in `CallableStatement.setOutputParameters()'.

   * Enabled callable statement caching via `cacheCallableStmts'
     property.

   * Fixed sending of split packets for large queries, enabled nio
     ability to send large packets as well.

   * Added `.toString()' functionality to `ServerPreparedStatement',
     which should help if you're trying to debug a query that is a
     prepared statement (it shows SQL as the server would process).

   * Added `logSlowQueries' property, along with
     `slowQueriesThresholdMillis' property to control when a query
     should be considered `slow.'

   * Removed wrapping of exceptions in `MysqlIO.changeUser()'.

   * Fixed stored procedure parameter parsing info when size was
     specified for a parameter (for example, `char()', `varchar()').

   * `ServerPreparedStatements' weren't actually de-allocating
     server-side resources when `.close()' was called.

   * Fixed case when no output parameters specified for a stored
     procedure caused a bogus query to be issued to retrieve out
     parameters, leading to a syntax error from the server.


File: manual.info,  Node: cj-news-3-1-1,  Next: cj-news-3-1-0,  Prev: cj-news-3-1-2,  Up: cg-news-3-1

C.5.3.15 Changes in MySQL Connector/J 3.1.1 (14 February 2004)
..............................................................

Bugs fixed:

   * Use DocBook version of docs for shipped versions of drivers.
     (Bug#2671 (http://bugs.mysql.com/2671))

   * `NULL' fields were not being encoded correctly in all cases in
     server-side prepared statements.  (Bug#2671
     (http://bugs.mysql.com/2671))

   * Fixed rare buffer underflow when writing numbers into buffers for
     sending prepared statement execution requests.  (Bug#2671
     (http://bugs.mysql.com/2671))

   * Fixed `ConnectionProperties' that weren't properly exposed via
     accessors, cleaned up `ConnectionProperties' code.  (Bug#2623
     (http://bugs.mysql.com/2623))

   * Class-cast exception when using scrolling result sets and
     server-side prepared statements.  (Bug#2623
     (http://bugs.mysql.com/2623))

   * Merged unbuffered input code from 3.0.  (Bug#2623
     (http://bugs.mysql.com/2623))

   * Enabled streaming of result sets from server-side prepared
     statements.  (Bug#2606 (http://bugs.mysql.com/2606))

   * Server-side prepared statements were not returning datatype `YEAR'
     correctly.  (Bug#2606 (http://bugs.mysql.com/2606))

   * Fixed charset conversion issue in `getTables()'.  (Bug#2502
     (http://bugs.mysql.com/2502))

   * Implemented multiple result sets returned from a statement or
     stored procedure.  (Bug#2502 (http://bugs.mysql.com/2502))

   * Implemented `Connection.prepareCall()', and `DatabaseMetaData'.
     `getProcedures()' and `getProcedureColumns()'.  (Bug#2359
     (http://bugs.mysql.com/2359))

   * Merged prepared statement caching, and `.getMetaData()' support
     from 3.0 branch.  (Bug#2359 (http://bugs.mysql.com/2359))

   * Fixed off-by-1900 error in some cases for years in
     `TimeUtil.fastDate'/`TimeCreate()' when unpacking results from
     server-side prepared statements.  (Bug#2359
     (http://bugs.mysql.com/2359))

   * Reset `long binary' parameters in `ServerPreparedStatement' when
     `clearParameters()' is called, by sending `COM_RESET_STMT' to the
     server.  (Bug#2359 (http://bugs.mysql.com/2359))

   * `NULL' values for numeric types in binary encoded result sets
     causing `NullPointerExceptions'.  (Bug#2359
     (http://bugs.mysql.com/2359))

   * Display where/why a connection was implicitly closed (to aid
     debugging).  (Bug#1673 (http://bugs.mysql.com/1673))

   * `DatabaseMetaData.getColumns()' is not returning correct column
     ordinal info for non-`'%'' column name patterns.  (Bug#1673
     (http://bugs.mysql.com/1673))

   * Fixed `NullPointerException' in
     `ServerPreparedStatement.setTimestamp()', as well as year and
     month descrepencies in `ServerPreparedStatement.setTimestamp()',
     `setDate()'.  (Bug#1673 (http://bugs.mysql.com/1673))

   * Added ability to have multiple database/JVM targets for compliance
     and regression/unit tests in `build.xml'.  (Bug#1673
     (http://bugs.mysql.com/1673))

   * Fixed sending of queries larger than 16M.  (Bug#1673
     (http://bugs.mysql.com/1673))

   * Merged fix of datatype mapping from MySQL type `FLOAT' to
     `java.sql.Types.REAL' from 3.0 branch.  (Bug#1673
     (http://bugs.mysql.com/1673))

   * Fixed NPE and year/month bad conversions when accessing some
     datetime functionality in `ServerPreparedStatements' and their
     resultant result sets.  (Bug#1673 (http://bugs.mysql.com/1673))

   * Added named and indexed input/output parameter support to
     `CallableStatement'. MySQL-5.0.x or newer.  (Bug#1673
     (http://bugs.mysql.com/1673))

   * `CommunicationsException' implemented, that tries to determine why
     communications was lost with a server, and displays possible
     reasons when `.getMessage()' is called.  (Bug#1673
     (http://bugs.mysql.com/1673))

   * Detect collation of column for `RSMD.isCaseSensitive()'.
     (Bug#1673 (http://bugs.mysql.com/1673))

   * Optimized `Buffer.readLenByteArray()' to return shared empty byte
     array when length is 0.

   * Fix support for table aliases when checking for all primary keys
     in `UpdatableResultSet'.

   * Unpack `unknown' data types from server prepared statements as
     `Strings'.

   * Implemented `Statement.getWarnings()' for MySQL-4.1 and newer
     (using `SHOW WARNINGS').

   * Ensure that warnings are cleared before executing queries on
     prepared statements, as-per JDBC spec (now that we support
     warnings).

   * Correctly initialize datasource properties from JNDI Refs,
     including explicitly specified URLs.

   * Implemented long data (Blobs, Clobs, InputStreams, Readers) for
     server prepared statements.

   * Deal with 0-length tokens in `EscapeProcessor' (caused by callable
     statement escape syntax).

   * `DatabaseMetaData' now reports `supportsStoredProcedures()' for
     MySQL versions >= 5.0.0

   * Support for *Note `mysql_change_user()': mysql-change-user. See the
     `changeUser()' method in `com.mysql.jdbc.Connection'.

   * Removed `useFastDates' connection property.

   * Support for NIO. Use `useNIO=true' on platforms that support NIO.

   * Check for closed connection on delete/update/insert row operations
     in `UpdatableResultSet'.

   * Support for transaction savepoints (MySQL >= 4.0.14 or 4.1.1).

   * Support `old' `profileSql' capitalization in
     `ConnectionProperties'. This property is deprecated, you should use
     `profileSQL' if possible.

   * Fixed character encoding issues when converting bytes to ASCII
     when MySQL doesn't provide the character set, and the JVM is set
     to a multi-byte encoding (usually affecting retrieval of numeric
     values).

   * Centralized setting of result set type and concurrency.

   * Fixed bug with `UpdatableResultSets' not using client-side
     prepared statements.

   * Default result set type changed to `TYPE_FORWARD_ONLY' (JDBC
     compliance).

   * Fixed `IllegalAccessError' to `Calendar.getTimeInMillis()' in
     `DateTimeValue' (for JDK < 1.4).

   * Allow contents of `PreparedStatement.setBlob()' to be retained
     between calls to `.execute*()'.

   * Fixed stack overflow in `Connection.prepareCall()' (bad merge).

   * Refactored how connection properties are set and exposed as
     `DriverPropertyInfo' as well as `Connection' and `DataSource'
     properties.

   * Reduced number of methods called in average query to be more
     efficient.

   * Prepared `Statements' will be re-prepared on auto-reconnect. Any
     errors encountered are postponed until first attempt to re-execute
     the re-prepared statement.


File: manual.info,  Node: cj-news-3-1-0,  Prev: cj-news-3-1-1,  Up: cg-news-3-1

C.5.3.16 Changes in MySQL Connector/J 3.1.0 (18 February 2003)
..............................................................

Bugs fixed:

   * Added `useServerPrepStmts' property (default `false'). The driver
     will use server-side prepared statements when the server version
     supports them (4.1 and newer) when this property is set to `true'.
     It is currently set to `false' by default until all bind/fetch
     functionality has been implemented. Currently only DML prepared
     statements are implemented for 4.1 server-side prepared statements.

   * Added `requireSSL' property.

   * Track open `Statements', close all when `Connection.close()' is
     called (JDBC compliance).


File: manual.info,  Node: cg-news-3-0,  Next: cj-news-2-0,  Prev: cg-news-3-1,  Up: cj-news

C.5.4 Changes in MySQL Connector/J 3.0.x
----------------------------------------

* Menu:

* cj-news-3-0-17::               Changes in MySQL Connector/J 3.0.17 (23 June 2005)
* cj-news-3-0-16::               Changes in MySQL Connector/J 3.0.16 (15 November 2004)
* cj-news-3-0-15::               Changes in MySQL Connector/J 3.0.15 (04 September 2004)
* cj-news-3-0-14::               Changes in MySQL Connector/J 3.0.14 (28 May 2004)
* cj-news-3-0-13::               Changes in MySQL Connector/J 3.0.13 (27 May 2004)
* cj-news-3-0-12::               Changes in MySQL Connector/J 3.0.12 (18 May 2004)
* cj-news-3-0-11::               Changes in MySQL Connector/J 3.0.11 (19 February 2004)
* cj-news-3-0-10::               Changes in MySQL Connector/J 3.0.10 (13 January 2004)
* cj-news-3-0-9::                Changes in MySQL Connector/J 3.0.9 (07 October 2003)
* cj-news-3-0-8::                Changes in MySQL Connector/J 3.0.8 (23 May 2003)
* cj-news-3-0-7::                Changes in MySQL Connector/J 3.0.7 (08 April 2003)
* cj-news-3-0-6::                Changes in MySQL Connector/J 3.0.6 (18 February 2003)
* cj-news-3-0-5::                Changes in MySQL Connector/J 3.0.5 (22 January 2003)
* cj-news-3-0-4::                Changes in MySQL Connector/J 3.0.4 (06 January 2003)
* cj-news-3-0-3::                Changes in MySQL Connector/J 3.0.3 (17 December 2002)
* cj-news-3-0-2::                Changes in MySQL Connector/J 3.0.2 (08 November 2002)
* cj-news-3-0-1::                Changes in MySQL Connector/J 3.0.1 (21 September 2002)
* cj-news-3-0-0::                Changes in MySQL Connector/J 3.0.0 (31 July 2002)


File: manual.info,  Node: cj-news-3-0-17,  Next: cj-news-3-0-16,  Prev: cg-news-3-0,  Up: cg-news-3-0

C.5.4.1 Changes in MySQL Connector/J 3.0.17 (23 June 2005)
..........................................................

Bugs fixed:

   * Workaround for server Bug#9098 (http://bugs.mysql.com/9098):
     Default values of `CURRENT_*' for `DATE', `TIME', `DATETIME', and
     `TIMESTAMP' columns can't be distinguished from `string' values, so
     `UpdatableResultSet.moveToInsertRow()' generates bad SQL for
     inserting default values.  (Bug#8812 (http://bugs.mysql.com/8812))

   * `NON_UNIQUE' column from `DBMD.getIndexInfo()' returned inverted
     value.  (Bug#8812 (http://bugs.mysql.com/8812))

   * `EUCKR' charset is sent as `SET NAMES euc_kr' which MySQL-4.1 and
     newer doesn't understand.  (Bug#8629 (http://bugs.mysql.com/8629))

   * Added support for the `EUC_JP_Solaris' character encoding, which
     maps to a MySQL encoding of `eucjpms' (backported from 3.1
     branch). This only works on servers that support `eucjpms', namely
     5.0.3 or later.  (Bug#8629 (http://bugs.mysql.com/8629))

   * Use hex escapes for `PreparedStatement.setBytes()' for double-byte
     charsets including `aliases' `Windows-31J', `CP934', `MS932'.
     (Bug#8629 (http://bugs.mysql.com/8629))

   * `DatabaseMetaData.supportsSelectForUpdate()' returns correct value
     based on server version.  (Bug#8629 (http://bugs.mysql.com/8629))

   * Which requires hex escaping of binary data when using multi-byte
     charsets with prepared statements.  (Bug#8064
     (http://bugs.mysql.com/8064))

   * Fixed duplicated code in `configureClientCharset()' that prevented
     `useOldUTF8Behavior=true' from working properly.  (Bug#7952
     (http://bugs.mysql.com/7952))

   * Backported SQLState codes mapping from Connector/J 3.1, enable
     with `useSqlStateCodes=true' as a connection property, it defaults
     to `false' in this release, so that we don't break legacy
     applications (it defaults to `true' starting with Connector/J 3.1).
     (Bug#7686 (http://bugs.mysql.com/7686))

   * Timestamp key column data needed `_binary' stripped for
     `UpdatableResultSet.refreshRow()'.  (Bug#7686
     (http://bugs.mysql.com/7686))

   * `MS932', `SHIFT_JIS', and `Windows_31J' not recognized as aliases
     for `sjis'.  (Bug#7607 (http://bugs.mysql.com/7607))

   * Handle streaming result sets with more than 2 billion rows
     properly by fixing wraparound of row number counter.  (Bug#7601
     (http://bugs.mysql.com/7601))

   * `PreparedStatement.fixDecimalExponent()' adding extra `+', making
     number unparseable by MySQL server.  (Bug#7601
     (http://bugs.mysql.com/7601))

   * Escape sequence {fn convert(..., type)} now supports ODBC-style
     types that are prepended by `SQL_'.  (Bug#7601
     (http://bugs.mysql.com/7601))

   * Statements created from a pooled connection were returning
     physical connection instead of logical connection when
     `getConnection()' was called.  (Bug#7316
     (http://bugs.mysql.com/7316))

   * Support new protocol type `MYSQL_TYPE_VARCHAR'.  (Bug#7081
     (http://bugs.mysql.com/7081))

   * Added `useOldUTF8Behavior'' configuration property, which causes
     JDBC driver to act like it did with MySQL-4.0.x and earlier when
     the character encoding is `utf-8' when connected to MySQL-4.1 or
     newer.  (Bug#7081 (http://bugs.mysql.com/7081))

   * `DatabaseMetaData.getIndexInfo()' ignored `unique' parameter.
     (Bug#7081 (http://bugs.mysql.com/7081))

   * `PreparedStatement.fixDecimalExponent()' adding extra `+', making
     number unparseable by MySQL server.  (Bug#7061
     (http://bugs.mysql.com/7061))

   * `PreparedStatements' don't encode Big5 (and other multi-byte)
     character sets correctly in static SQL strings.  (Bug#7033
     (http://bugs.mysql.com/7033))

   * Connections starting up failed-over (due to down master) never
     retry master.  (Bug#6966 (http://bugs.mysql.com/6966))

   * Adding `CP943' to aliases for `sjis'.  (Bug#6549
     (http://bugs.mysql.com/6549), Bug#7607
     (http://bugs.mysql.com/7607))

   * `Timestamp'/`Time' conversion goes in the wrong `direction' when
     `useTimeZone=true' and server time zone differs from client time
     zone.  (Bug#5874 (http://bugs.mysql.com/5874))


File: manual.info,  Node: cj-news-3-0-16,  Next: cj-news-3-0-15,  Prev: cj-news-3-0-17,  Up: cg-news-3-0

C.5.4.2 Changes in MySQL Connector/J 3.0.16 (15 November 2004)
..............................................................

Bugs fixed:

   * Made `TINYINT(1)' -> `BIT'/`Boolean' conversion configurable via
     `tinyInt1isBit' property (default `true' to be JDBC compliant out
     of the box).  (Bug#5664 (http://bugs.mysql.com/5664))

   * Off-by-one bug in `Buffer.readString(STRING)'.  (Bug#5664
     (http://bugs.mysql.com/5664))

   * `ResultSet.updateByte()' when on insert row throws
     `ArrayOutOfBoundsException'.  (Bug#5664
     (http://bugs.mysql.com/5664))

   * Fixed regression where `useUnbufferedInput' was defaulting to
     `false'.  (Bug#5664 (http://bugs.mysql.com/5664))

   * `ResultSet.getTimestamp()' on a column with `TIME' in it fails.
     (Bug#5664 (http://bugs.mysql.com/5664))

   * Fixed `DatabaseMetaData.getTypes()' returning incorrect (this is,
     non-negative) scale for the `NUMERIC' type.  (Bug#5664
     (http://bugs.mysql.com/5664))

   * Only set `character_set_results' during connection establishment
     if server version >= 4.1.1.  (Bug#5664
     (http://bugs.mysql.com/5664))

   * Fixed `ResultSetMetaData.isReadOnly()' to detect non-writable
     columns when connected to MySQL-4.1 or newer, based on existence
     of `original' table and column names.

   * Re-issue character set configuration commands when re-using pooled
     connections and/or `Connection.changeUser()' when connected to
     MySQL-4.1 or newer.


File: manual.info,  Node: cj-news-3-0-15,  Next: cj-news-3-0-14,  Prev: cj-news-3-0-16,  Up: cg-news-3-0

C.5.4.3 Changes in MySQL Connector/J 3.0.15 (04 September 2004)
...............................................................

Bugs fixed:

   * `ResultSet.getMetaData()' should not return incorrectly
     initialized metadata if the result set has been closed, but should
     instead throw an `SQLException'. Also fixed for `getRow()' and
     `getWarnings()' and traversal methods by calling `checkClosed()'
     before operating on instance-level fields that are nullified during
     `.close()'.  (Bug#5069 (http://bugs.mysql.com/5069))

   * Use `_binary' introducer for `PreparedStatement.setBytes()' and
     `set*Stream()' when connected to MySQL-4.1.x or newer to avoid
     misinterpretation during character conversion.  (Bug#5069
     (http://bugs.mysql.com/5069))

   * Parse new time zone variables from 4.1.x servers.  (Bug#5069
     (http://bugs.mysql.com/5069))

   * `ResultSet' should release `Field[]' instance in `.close()'.
     (Bug#5022 (http://bugs.mysql.com/5022))

   * `RSMD.getPrecision()' returning 0 for non-numeric types (should
     return max length in chars for non-binary types, max length in
     bytes for binary types). This fix also fixes mapping of
     `RSMD.getColumnType()' and `RSMD.getColumnTypeName()' for the
     `BLOB' types based on the length sent from the server (the server
     doesn't distinguish between `TINYBLOB', `BLOB', `MEDIUMBLOB' or
     `LONGBLOB' at the network protocol level).  (Bug#4880
     (http://bugs.mysql.com/4880))

   * `Production' is now `GA' (General Availability) in naming scheme
     of distributions.  (Bug#4860 (http://bugs.mysql.com/4860),
     Bug#4138 (http://bugs.mysql.com/4138))

   * `DBMD.getColumns()' returns incorrect JDBC type for unsigned
     columns. This affects type mappings for all numeric types in the
     `RSMD.getColumnType()' and `RSMD.getColumnTypeNames()' methods as
     well, to ensure that `like' types from `DBMD.getColumns()' match
     up with what `RSMD.getColumnType()' and `getColumnTypeNames()'
     return.  (Bug#4860 (http://bugs.mysql.com/4860), Bug#4138
     (http://bugs.mysql.com/4138))

   * Calling `.close()' twice on a `PooledConnection' causes NPE.
     (Bug#4808 (http://bugs.mysql.com/4808))

   * `DOUBLE' mapped twice in `DBMD.getTypeInfo()'.  (Bug#4742
     (http://bugs.mysql.com/4742))

   * Added FLOSS license exemption.  (Bug#4742
     (http://bugs.mysql.com/4742))

   * Removed redundant calls to `checkRowPos()' in `ResultSet'.
     (Bug#4334 (http://bugs.mysql.com/4334))

   * Failover for `autoReconnect' not using port numbers for any hosts,
     and not retrying all hosts.

     *Warning*:

     This required a change to the `SocketFactory' `connect()' method
     signature, which is now `public Socket connect(String host, int
     portNumber, Properties props)'; therefore, any third-party socket
     factories will have to be changed to support this signature.

     (Bug#4334 (http://bugs.mysql.com/4334))

   * Logical connections created by `MysqlConnectionPoolDataSource'
     will now issue a `rollback()' when they are closed and sent back
     to the pool. If your application server/connection pool already
     does this for you, you can set the `rollbackOnPooledClose'
     property to `false' to avoid the overhead of an extra `rollback()'.
     (Bug#4334 (http://bugs.mysql.com/4334))

   * `StringUtils.escapeEasternUnicodeByteStream' was still broken for
     GBK.  (Bug#4010 (http://bugs.mysql.com/4010))


File: manual.info,  Node: cj-news-3-0-14,  Next: cj-news-3-0-13,  Prev: cj-news-3-0-15,  Up: cg-news-3-0

C.5.4.4 Changes in MySQL Connector/J 3.0.14 (28 May 2004)
.........................................................

Bugs fixed:

   * Fixed URL parsing error.


File: manual.info,  Node: cj-news-3-0-13,  Next: cj-news-3-0-12,  Prev: cj-news-3-0-14,  Up: cg-news-3-0

C.5.4.5 Changes in MySQL Connector/J 3.0.13 (27 May 2004)
.........................................................

Bugs fixed:

   * `No Database Selected' when using `MysqlConnectionPoolDataSource'.
     (Bug#3920 (http://bugs.mysql.com/3920))

   * `PreparedStatement.getGeneratedKeys()' method returns only 1
     result for batched insertions.  (Bug#3873
     (http://bugs.mysql.com/3873))

   * Using a `MySQLDatasource' without server name fails.  (Bug#3848
     (http://bugs.mysql.com/3848))


File: manual.info,  Node: cj-news-3-0-12,  Next: cj-news-3-0-11,  Prev: cj-news-3-0-13,  Up: cg-news-3-0

C.5.4.6 Changes in MySQL Connector/J 3.0.12 (18 May 2004)
.........................................................

Bugs fixed:

   * Inconsistent reporting of data type. The server still doesn't
     return all types for *BLOBs *TEXT correctly, so the driver won't
     return those correctly.  (Bug#3570 (http://bugs.mysql.com/3570))

   * `UpdatableResultSet' not picking up default values for
     `moveToInsertRow()'.  (Bug#3557 (http://bugs.mysql.com/3557))

   * Not specifying database in URL caused `MalformedURL' exception.
     (Bug#3554 (http://bugs.mysql.com/3554))

   * Auto-convert MySQL encoding names to Java encoding names if used
     for `characterEncoding' property.  (Bug#3554
     (http://bugs.mysql.com/3554))

   * Use `junit.textui.TestRunner' for all unit tests (to allow them to
     be run from the command line outside of Ant or Eclipse).
     (Bug#3554 (http://bugs.mysql.com/3554))

   * Added encoding names that are recognized on some JVMs to fix case
     where they were reverse-mapped to MySQL encoding names incorrectly.
     (Bug#3554 (http://bugs.mysql.com/3554))

   * Made `StringRegressionTest' 4.1-unicode aware.  (Bug#3520
     (http://bugs.mysql.com/3520))

   * Fixed regression in `PreparedStatement.setString()' and eastern
     character encodings.  (Bug#3520 (http://bugs.mysql.com/3520))

   * `DBMD.getSQLStateType()' returns incorrect value.  (Bug#3520
     (http://bugs.mysql.com/3520))

   * Renamed `StringUtils.escapeSJISByteStream()' to more appropriate
     `escapeEasternUnicodeByteStream()'.  (Bug#3511
     (http://bugs.mysql.com/3511))

   * `StringUtils.escapeSJISByteStream()' not covering all eastern
     double-byte charsets correctly.  (Bug#3511
     (http://bugs.mysql.com/3511))

   * Return creating statement for `ResultSets' created by
     `getGeneratedKeys()'.  (Bug#2957 (http://bugs.mysql.com/2957))

   * Use `SET character_set_results' during initialization to allow any
     charset to be returned to the driver for result sets.  (Bug#2670
     (http://bugs.mysql.com/2670))

   * Don't truncate `BLOB' or `CLOB' values when using `setBytes()'
     and/or `setBinary/CharacterStream()'. .  (Bug#2670
     (http://bugs.mysql.com/2670))

   * Dynamically configure character set mappings for field-level
     character sets on MySQL-4.1.0 and newer using `SHOW COLLATION'
     when connecting.  (Bug#2670 (http://bugs.mysql.com/2670))

   * Map `binary' character set to `US-ASCII' to support `DATETIME'
     charset recognition for servers >= 4.1.2.  (Bug#2670
     (http://bugs.mysql.com/2670))

   * Use `charsetnr' returned during connect to encode queries before
     issuing `SET NAMES' on MySQL >= 4.1.0.  (Bug#2670
     (http://bugs.mysql.com/2670))

   * Add helper methods to `ResultSetMetaData'
     (`getColumnCharacterEncoding()' and `getColumnCharacterSet()') to
     allow end-users to see what charset the driver thinks it should be
     using for the column.  (Bug#2670 (http://bugs.mysql.com/2670))

   * Only set `character_set_results' for MySQL >= 4.1.0.  (Bug#2670
     (http://bugs.mysql.com/2670))

   * Allow `url' parameter for `MysqlDataSource' and
     `MysqlConnectionPool' `DataSource' so that passing of other
     properties is possible from inside appservers.

   * Don't escape SJIS/GBK/BIG5 when using MySQL-4.1 or newer.

   * Backport documentation tooling from 3.1 branch.

   * Added `failOverReadOnly' property, to allow end-user to configure
     state of connection (read-only/writable) when failed over.

   * Allow `java.util.Date' to be sent in as parameter to
     `PreparedStatement.setObject()', converting it to a `Timestamp' to
     maintain full precision. .  (Bug#103 (http://bugs.mysql.com/103))

   * Add unsigned attribute to `DatabaseMetaData.getColumns()' output
     in the `TYPE_NAME' column.

   * Map duplicate key and foreign key errors to SQLState of `23000'.

   * Backported `change user' and `reset server state' functionality
     from 3.1 branch, to allow clients of
     `MysqlConnectionPoolDataSource' to reset server state on
     `getConnection()' on a pooled connection.


File: manual.info,  Node: cj-news-3-0-11,  Next: cj-news-3-0-10,  Prev: cj-news-3-0-12,  Up: cg-news-3-0

C.5.4.7 Changes in MySQL Connector/J 3.0.11 (19 February 2004)
..............................................................

Bugs fixed:

   * Return `java.lang.Double' for `FLOAT' type from
     `ResultSetMetaData.getColumnClassName()'.  (Bug#2855
     (http://bugs.mysql.com/2855))

   * Return `[B' instead of `java.lang.Object' for `BINARY',
     `VARBINARY' and `LONGVARBINARY' types from
     `ResultSetMetaData.getColumnClassName()' (JDBC compliance).
     (Bug#2855 (http://bugs.mysql.com/2855))

   * Issue connection events on all instances created from a
     `ConnectionPoolDataSource'.  (Bug#2855
     (http://bugs.mysql.com/2855))

   * Return `java.lang.Integer' for `TINYINT' and `SMALLINT' types from
     `ResultSetMetaData.getColumnClassName()'.  (Bug#2852
     (http://bugs.mysql.com/2852))

   * Added `useUnbufferedInput' parameter, and now use it by default
     (due to JVM issue
     `http://developer.java.sun.com/developer/bugParade/bugs/4401235.html')
     (Bug#2578 (http://bugs.mysql.com/2578))

   * Fixed failover always going to last host in list.  (Bug#2578
     (http://bugs.mysql.com/2578))

   * Detect `on'/`off' or `1', `2', `3' form of
     `lower_case_table_names' value on server.  (Bug#2578
     (http://bugs.mysql.com/2578))

   * `AutoReconnect' time was growing faster than exponentially.
     (Bug#2447 (http://bugs.mysql.com/2447))

   * Trigger a `SET NAMES utf8' when encoding is forced to `utf8' _or_
     `utf-8' via the `characterEncoding' property. Previously, only the
     Java-style encoding name of `utf-8' would trigger this.


File: manual.info,  Node: cj-news-3-0-10,  Next: cj-news-3-0-9,  Prev: cj-news-3-0-11,  Up: cg-news-3-0

C.5.4.8 Changes in MySQL Connector/J 3.0.10 (13 January 2004)
.............................................................

Bugs fixed:

   * Enable caching of the parsing stage of prepared statements via the
     `cachePrepStmts', `prepStmtCacheSize', and `prepStmtCacheSqlLimit'
     properties (disabled by default).  (Bug#2006
     (http://bugs.mysql.com/2006))

   * Fixed security exception when used in Applets (applets can't read
     the system property `file.encoding' which is needed for `LOAD DATA
     LOCAL INFILE').  (Bug#2006 (http://bugs.mysql.com/2006))

   * Speed up parsing of `PreparedStatements', try to use one-pass
     whenever possible.  (Bug#2006 (http://bugs.mysql.com/2006))

   * Fixed exception `Unknown character set 'danish'' on connect with
     JDK-1.4.0 (Bug#2006 (http://bugs.mysql.com/2006))

   * Fixed mappings in SQLError to report deadlocks with SQLStates of
     `41000'.  (Bug#2006 (http://bugs.mysql.com/2006))

   * Removed static synchronization bottleneck from instance factory
     method of `SingleByteCharsetConverter'.  (Bug#2006
     (http://bugs.mysql.com/2006))

   * Removed static synchronization bottleneck from
     `PreparedStatement.setTimestamp()'.  (Bug#2006
     (http://bugs.mysql.com/2006))

   * `ResultSet.findColumn()' should use first matching column name
     when there are duplicate column names in `SELECT' query
     (JDBC-compliance).  (Bug#2006 (http://bugs.mysql.com/2006))

   * `maxRows' property would affect internal statements, so check it
     for all statement creation internal to the driver, and set to 0
     when it is not.  (Bug#2006 (http://bugs.mysql.com/2006))

   * Use constants for SQLStates.  (Bug#2006
     (http://bugs.mysql.com/2006))

   * Map charset `ko18_ru' to `ko18r' when connected to MySQL-4.1.0 or
     newer.  (Bug#2006 (http://bugs.mysql.com/2006))

   * Ensure that `Buffer.writeString()' saves room for the `\0'.
     (Bug#2006 (http://bugs.mysql.com/2006))

   * `ArrayIndexOutOfBounds' when parameter number == number of
     parameters + 1.  (Bug#1958 (http://bugs.mysql.com/1958))

   * Connection property `maxRows' not honored.  (Bug#1933
     (http://bugs.mysql.com/1933))

   * Statements being created too many times in
     `DBMD.extractForeignKeyFromCreateTable()'.  (Bug#1925
     (http://bugs.mysql.com/1925))

   * Support escape sequence {fn convert ... }.  (Bug#1914
     (http://bugs.mysql.com/1914))

   * Implement `ResultSet.updateClob()'.  (Bug#1913
     (http://bugs.mysql.com/1913))

   * Autoreconnect code didn't set catalog upon reconnect if it had
     been changed.  (Bug#1913 (http://bugs.mysql.com/1913))

   * `ResultSet.getObject()' on `TINYINT' and `SMALLINT' columns should
     return Java type `Integer'.  (Bug#1913
     (http://bugs.mysql.com/1913))

   * Added more descriptive error message `Server Configuration Denies
     Access to DataSource', as well as retrieval of message from server.
     (Bug#1913 (http://bugs.mysql.com/1913))

   * `ResultSetMetaData.isCaseSensitive()' returned wrong value for
     `CHAR'/`VARCHAR' columns.  (Bug#1913 (http://bugs.mysql.com/1913))

   * Added `alwaysClearStream' connection property, which causes the
     driver to always empty any remaining data on the input stream
     before each query.  (Bug#1913 (http://bugs.mysql.com/1913))

   * `DatabaseMetaData.getSystemFunction()' returning bad function
     `VResultsSion'.  (Bug#1775 (http://bugs.mysql.com/1775))

   * Foreign Keys column sequence is not consistent in
     `DatabaseMetaData.getImported/Exported/CrossReference()'.
     (Bug#1731 (http://bugs.mysql.com/1731))

   * Fix for `ArrayIndexOutOfBounds' exception when using
     `Statement.setMaxRows()'.  (Bug#1695 (http://bugs.mysql.com/1695))

   * Subsequent call to `ResultSet.updateFoo()' causes NPE if result
     set is not updatable.  (Bug#1630 (http://bugs.mysql.com/1630))

   * Fix for 4.1.1-style authentication with no password.  (Bug#1630
     (http://bugs.mysql.com/1630))

   * Cross-database updatable result sets are not checked for
     updatability correctly.  (Bug#1592 (http://bugs.mysql.com/1592))

   * `DatabaseMetaData.getColumns()' should return `Types.LONGVARCHAR'
     for MySQL `LONGTEXT' type.  (Bug#1592 (http://bugs.mysql.com/1592))

   * Fixed regression of `Statement.getGeneratedKeys()' and `REPLACE'
     statements.  (Bug#1576 (http://bugs.mysql.com/1576))

   * Barge blobs and split packets not being read correctly.  (Bug#1576
     (http://bugs.mysql.com/1576))

   * Backported fix for aliased tables and `UpdatableResultSets' in
     `checkUpdatability()' method from 3.1 branch.  (Bug#1534
     (http://bugs.mysql.com/1534))

   * `Friendlier' exception message for `PacketTooLargeException'.
     (Bug#1534 (http://bugs.mysql.com/1534))

   * Don't count quoted IDs when inside a 'string' in
     `PreparedStatement' parsing.  (Bug#1511
     (http://bugs.mysql.com/1511))


File: manual.info,  Node: cj-news-3-0-9,  Next: cj-news-3-0-8,  Prev: cj-news-3-0-10,  Up: cg-news-3-0

C.5.4.9 Changes in MySQL Connector/J 3.0.9 (07 October 2003)
............................................................

Bugs fixed:

   * `ResultSet.get/setString' mashing char 127.  (Bug#1247
     (http://bugs.mysql.com/1247))

   * Added property to `clobber' streaming results, by setting the
     `clobberStreamingResults' property to `true' (the default is
     `false'). This will cause a `streaming' `ResultSet' to be
     automatically closed, and any oustanding data still streaming from
     the server to be discarded if another query is executed before all
     the data has been read from the server.  (Bug#1247
     (http://bugs.mysql.com/1247))

   * Added `com.mysql.jdbc.util.BaseBugReport' to help creation of
     testcases for bug reports.  (Bug#1247 (http://bugs.mysql.com/1247))

   * Backported authentication changes for 4.1.1 and newer from 3.1
     branch.  (Bug#1247 (http://bugs.mysql.com/1247))

   * Made `databaseName', `portNumber', and `serverName' optional
     parameters for `MysqlDataSourceFactory'.  (Bug#1246
     (http://bugs.mysql.com/1246))

   * Optimized `CLOB.setChracterStream()'.  (Bug#1131
     (http://bugs.mysql.com/1131))

   * Fixed `CLOB.truncate()'.  (Bug#1130 (http://bugs.mysql.com/1130))

   * Fixed deadlock issue with `Statement.setMaxRows()'.  (Bug#1099
     (http://bugs.mysql.com/1099))

   * `DatabaseMetaData.getColumns()' getting confused about the keyword
     `set' in character columns.  (Bug#1099
     (http://bugs.mysql.com/1099))

   * Clip +/- INF (to smallest and largest representative values for
     the type in MySQL) and NaN (to 0) for `setDouble'/`setFloat()', and
     issue a warning on the statement when the server does not support
     +/- INF or NaN.  (Bug#884 (http://bugs.mysql.com/884))

   * Don't fire connection closed events when closing pooled
     connections, or on `PooledConnection.getConnection()' with already
     open connections.  (Bug#884 (http://bugs.mysql.com/884))

   * Double-escaping of `'\'' when charset is SJIS or GBK and `'\''
     appears in non-escaped input.  (Bug#879
     (http://bugs.mysql.com/879))

   * When emptying input stream of unused rows for `streaming' result
     sets, have the current thread `yield()' every 100 rows in order to
     not monopolize CPU time.  (Bug#879 (http://bugs.mysql.com/879))

   * Issue exception on `ResultSet.getXXX()' on empty result set
     (wasn't caught in some cases).  (Bug#848
     (http://bugs.mysql.com/848))

   * Don't hide messages from exceptions thrown in I/O layers.
     (Bug#848 (http://bugs.mysql.com/848))

   * Fixed regression in large split-packet handling.  (Bug#848
     (http://bugs.mysql.com/848))

   * Better diagnostic error messages in exceptions for `streaming'
     result sets.  (Bug#848 (http://bugs.mysql.com/848))

   * Don't change timestamp TZ twice if `useTimezone==true'.  (Bug#774
     (http://bugs.mysql.com/774))

   * Don't wrap `SQLExceptions' in `RowDataDynamic'.  (Bug#688
     (http://bugs.mysql.com/688))

   * Don't try and reset isolation level on reconnect if MySQL doesn't
     support them.  (Bug#688 (http://bugs.mysql.com/688))

   * The `insertRow' in an `UpdatableResultSet' is now loaded with the
     default column values when `moveToInsertRow()' is called.
     (Bug#688 (http://bugs.mysql.com/688))

   * `DatabaseMetaData.getColumns()' wasn't returning `NULL' for
     default values that are specified as `NULL'.  (Bug#688
     (http://bugs.mysql.com/688))

   * Change default statement type/concurrency to `TYPE_FORWARD_ONLY'
     and `CONCUR_READ_ONLY' (spec compliance).  (Bug#688
     (http://bugs.mysql.com/688))

   * Fix `UpdatableResultSet' to return values for `getXXX()' when on
     insert row.  (Bug#675 (http://bugs.mysql.com/675))

   * Support `InnoDB' contraint names when extracting foreign key
     information in `DatabaseMetaData' (implementing ideas from
     Parwinder Sekhon).  (Bug#664 (http://bugs.mysql.com/664), Bug#517
     (http://bugs.mysql.com/517))

   * Backported 4.1 protocol changes from 3.1 branch (server-side SQL
     states, new field information, larger client capability flags,
     connect-with-database, and so forth).  (Bug#664
     (http://bugs.mysql.com/664), Bug#517 (http://bugs.mysql.com/517))

   * `refreshRow' didn't work when primary key values contained values
     that needed to be escaped (they ended up being doubly escaped).
     (Bug#661 (http://bugs.mysql.com/661))

   * Fixed `ResultSet.previous()' behavior to move current position to
     before result set when on first row of result set.  (Bug#496
     (http://bugs.mysql.com/496))

   * Fixed `Statement' and `PreparedStatement' issuing bogus queries
     when `setMaxRows()' had been used and a `LIMIT' clause was present
     in the query.  (Bug#496 (http://bugs.mysql.com/496))

   * Faster date handling code in `ResultSet' and `PreparedStatement'
     (no longer uses `Date' methods that synchronize on static
     calendars).

   * Fixed test for end of buffer in `Buffer.readString()'.


File: manual.info,  Node: cj-news-3-0-8,  Next: cj-news-3-0-7,  Prev: cj-news-3-0-9,  Up: cg-news-3-0

C.5.4.10 Changes in MySQL Connector/J 3.0.8 (23 May 2003)
.........................................................

Bugs fixed:

   * Fixed SJIS encoding bug, thanks to Naoto Sato.  (Bug#378
     (http://bugs.mysql.com/378))

   * Fix problem detecting server character set in some cases.
     (Bug#378 (http://bugs.mysql.com/378))

   * Allow multiple calls to `Statement.close()'.  (Bug#378
     (http://bugs.mysql.com/378))

   * Return correct number of generated keys when using `REPLACE'
     statements.  (Bug#378 (http://bugs.mysql.com/378))

   * Unicode character 0xFFFF in a string would cause the driver to
     throw an `ArrayOutOfBoundsException'. .  (Bug#378
     (http://bugs.mysql.com/378))

   * Fix row data decoding error when using _very_ large packets.
     (Bug#378 (http://bugs.mysql.com/378))

   * Optimized row data decoding.  (Bug#378 (http://bugs.mysql.com/378))

   * Issue exception when operating on an already closed prepared
     statement.  (Bug#378 (http://bugs.mysql.com/378))

   * Optimized usage of `EscapeProcessor'.  (Bug#378
     (http://bugs.mysql.com/378))

   * Use JVM charset with filenames and `LOAD DATA [LOCAL] INFILE'.

   * Fix infinite loop with `Connection.cleanup()'.

   * Changed Ant target `compile-core' to `compile-driver', and made
     testsuite compilation a separate target.

   * Fixed result set not getting set for `Statement.executeUpdate()',
     which affected `getGeneratedKeys()' and `getUpdateCount()' in some
     cases.

   * Return list of generated keys when using multi-value `INSERTS' with
     `Statement.getGeneratedKeys()'.

   * Allow bogus URLs in `Driver.getPropertyInfo()'.


File: manual.info,  Node: cj-news-3-0-7,  Next: cj-news-3-0-6,  Prev: cj-news-3-0-8,  Up: cg-news-3-0

C.5.4.11 Changes in MySQL Connector/J 3.0.7 (08 April 2003)
...........................................................

Bugs fixed:

   * Fixed charset issues with database metadata (charset was not
     getting set correctly).

   * You can now toggle profiling on/off using
     `Connection.setProfileSql(boolean)'.

   * 4.1 Column Metadata fixes.

   * Fixed `MysqlPooledConnection.close()' calling wrong event type.

   * Fixed `StringIndexOutOfBoundsException' in
     `PreparedStatement.setClob()'.

   * `IOExceptions' during a transaction now cause the `Connection' to
     be closed.

   * Remove synchronization from `Driver.connect()' and
     `Driver.acceptsUrl()'.

   * Fixed missing conversion for `YEAR' type in
     `ResultSetMetaData.getColumnTypeName()'.

   * Updatable `ResultSets' can now be created for aliased
     tables/columns when connected to MySQL-4.1 or newer.

   * Fixed `LOAD DATA LOCAL INFILE' bug when file >
     `max_allowed_packet'.

   * Don't pick up indexes that start with `pri' as primary keys for
     `DBMD.getPrimaryKeys()'.

   * Ensure that packet size from `alignPacketSize()' does not exceed
     `max_allowed_packet' (JVM bug)

   * Don't reset `Connection.isReadOnly()' when autoReconnecting.

   * Fixed escaping of 0x5c (`'\'') character for GBK and Big5 charsets.

   * Fixed `ResultSet.getTimestamp()' when underlying field is of type
     `DATE'.

   * Throw `SQLExceptions' when trying to do operations on a forcefully
     closed `Connection' (that is, when a communication link failure
     occurs).


File: manual.info,  Node: cj-news-3-0-6,  Next: cj-news-3-0-5,  Prev: cj-news-3-0-7,  Up: cg-news-3-0

C.5.4.12 Changes in MySQL Connector/J 3.0.6 (18 February 2003)
..............................................................

Bugs fixed:

   * Backported 4.1 charset field info changes from Connector/J 3.1.

   * Fixed `Statement.setMaxRows()' to stop sending `LIMIT' type
     queries when not needed (performance).

   * Fixed `DBMD.getTypeInfo()' and `DBMD.getColumns()' returning
     different value for precision in `TEXT' and `BLOB' types.

   * Fixed `SQLExceptions' getting swallowed on initial connect.

   * Fixed `ResultSetMetaData' to return `""' when catalog not known.
     Fixes `NullPointerExceptions' with Sun's `CachedRowSet'.

   * Allow ignoring of warning for `non transactional tables' during
     rollback (compliance/usability) by setting `ignoreNonTxTables'
     property to `true'.

   * Clean up `Statement' query/method mismatch tests (that is,
     `INSERT' not allowed with `.executeQuery()').

   * Fixed `ResultSetMetaData.isWritable()' to return correct value.

   * More checks added in `ResultSet' traversal method to catch when in
     closed state.

   * Implemented `Blob.setBytes()'. You still need to pass the
     resultant `Blob' back into an updatable `ResultSet' or
     `PreparedStatement' to persist the changes, because MySQL does not
     support `locators'.

   * Add `window' of different `NULL' sorting behavior to
     `DBMD.nullsAreSortedAtStart' (4.0.2 to 4.0.10, true; otherwise,
     no).


File: manual.info,  Node: cj-news-3-0-5,  Next: cj-news-3-0-4,  Prev: cj-news-3-0-6,  Up: cg-news-3-0

C.5.4.13 Changes in MySQL Connector/J 3.0.5 (22 January 2003)
.............................................................

Bugs fixed:

   * Fixed `ResultSet.isBeforeFirst()' for empty result sets.

   * Added missing `LONGTEXT' type to `DBMD.getColumns()'.

   * Implemented an empty `TypeMap' for `Connection.getTypeMap()' so
     that some third-party apps work with MySQL (IBM WebSphere 5.0
     Connection pool).

   * Added update options for foreign key metadata.

   * Fixed `Buffer.fastSkipLenString()' causing `ArrayIndexOutOfBounds'
     exceptions with some queries when unpacking fields.

   * Quote table names in `DatabaseMetaData.getColumns()',
     `getPrimaryKeys()', `getIndexInfo()', `getBestRowIdentifier()'.

   * Retrieve `TX_ISOLATION' from database for
     `Connection.getTransactionIsolation()' when the MySQL version
     supports it, instead of an instance variable.

   * Greatly reduce memory required for `setBinaryStream()' in
     `PreparedStatements'.


File: manual.info,  Node: cj-news-3-0-4,  Next: cj-news-3-0-3,  Prev: cj-news-3-0-5,  Up: cg-news-3-0

C.5.4.14 Changes in MySQL Connector/J 3.0.4 (06 January 2003)
.............................................................

Bugs fixed:

   * Streamlined character conversion and `byte[]' handling in
     `PreparedStatements' for `setByte()'.

   * Fixed `PreparedStatement.executeBatch()' parameter overwriting.

   * Added quoted identifiers to database names for
     `Connection.setCatalog'.

   * Added support for 4.0.8-style large packets.

   * Reduce memory footprint of `PreparedStatements' by sharing
     outbound packet with `MysqlIO'.

   * Added `strictUpdates' property to allow control of amount of
     checking for `correctness' of updatable result sets. Set this to
     `false' if you want faster updatable result sets and you know that
     you create them from `SELECT' statements on tables with primary
     keys and that you have selected all primary keys in your query.

   * Added support for quoted identifiers in `PreparedStatement' parser.


File: manual.info,  Node: cj-news-3-0-3,  Next: cj-news-3-0-2,  Prev: cj-news-3-0-4,  Up: cg-news-3-0

C.5.4.15 Changes in MySQL Connector/J 3.0.3 (17 December 2002)
..............................................................

Bugs fixed:

   * Allow user to alter behavior of `Statement'/
     `PreparedStatement.executeBatch()' via `continueBatchOnError'
     property (defaults to `true').

   * More robust escape tokenizer: Recognize `--' comments, and allow
     nested escape sequences (see `testsuite.EscapeProcessingTest').

   * Fixed `Buffer.isLastDataPacket()' for 4.1 and newer servers.

   * `NamedPipeSocketFactory' now works (only intended for Windows),
     see `README' for instructions.

   * Changed `charsToByte' in `SingleByteCharConverter' to be
     non-static.

   * Use non-aliased table/column names and database names to fully
     qualify tables and columns in `UpdatableResultSet' (requires
     MySQL-4.1 or newer).

   * `LOAD DATA LOCAL INFILE ...' now works, if your server is
     configured to allow it. Can be turned off with the
     `allowLoadLocalInfile' property (see the `README').

   * Implemented `Connection.nativeSQL()'.

   * Fixed `ResultSetMetaData.getColumnTypeName()' returning `BLOB' for
     `TEXT' and `TEXT' for `BLOB' types.

   * Fixed charset handling in `Fields.java'.

   * Because of above, implemented
     `ResultSetMetaData.isAutoIncrement()' to use
     `Field.isAutoIncrement()'.

   * Substitute `'?'' for unknown character conversions in single-byte
     character sets instead of `'\0''.

   * Added `CLIENT_LONG_FLAG' to be able to get more column flags
     (`isAutoIncrement()' being the most important).

   * Honor `lower_case_table_names' when enabled in the server when
     doing table name comparisons in `DatabaseMetaData' methods.

   * `DBMD.getImported/ExportedKeys()' now handles multiple foreign
     keys per table.

   * More robust implementation of updatable result sets. Checks that
     _all_ primary keys of the table have been selected.

   * Some MySQL-4.1 protocol support (extended field info from selects).

   * Check for connection closed in more `Connection' methods
     (`createStatement', `prepareStatement', `setTransactionIsolation',
     `setAutoCommit').

   * Fixed `ResultSetMetaData.getPrecision()' returning incorrect
     values for some floating-point types.

   * Changed `SingleByteCharConverter' to use lazy initialization of
     each converter.


File: manual.info,  Node: cj-news-3-0-2,  Next: cj-news-3-0-1,  Prev: cj-news-3-0-3,  Up: cg-news-3-0

C.5.4.16 Changes in MySQL Connector/J 3.0.2 (08 November 2002)
..............................................................

Bugs fixed:

   * Implemented `Clob.setString()'.

   * Added `com.mysql.jdbc.MiniAdmin' class, which allows you to send
     `shutdown' command to MySQL server. This is intended to be used
     when `embedding' Java and MySQL server together in an end-user
     application.

   * Added SSL support. See `README' for information on how to use it.

   * All `DBMD' result set columns describing schemas now return `NULL'
     to be more compliant with the behavior of other JDBC drivers for
     other database systems (MySQL does not support schemas).

   * Use `SHOW CREATE TABLE' when possible for determining foreign key
     information for `DatabaseMetaData'. Also allows cascade options
     for `DELETE' information to be returned.

   * Implemented `Clob.setCharacterStream()'.

   * Failover and `autoReconnect' work only when the connection is in
     an `autoCommit(false)' state, in order to stay transaction-safe.

   * Fixed `DBMD.supportsResultSetConcurrency()' so that it returns
     `true' for `ResultSet.TYPE_SCROLL_INSENSITIVE' and
     `ResultSet.CONCUR_READ_ONLY' or `ResultSet.CONCUR_UPDATABLE'.

   * Implemented `Clob.setAsciiStream()'.

   * Removed duplicate code from `UpdatableResultSet' (it can be
     inherited from `ResultSet', the extra code for each method to
     handle updatability I thought might someday be necessary has not
     been needed).

   * Fixed `UnsupportedEncodingException' thrown when `forcing' a
     character encoding via properties.

   * Fixed incorrect conversion in `ResultSet.getLong()'.

   * Implemented `ResultSet.updateBlob()'.

   * Removed some not-needed temporary object creation by smarter use
     of `Strings' in `EscapeProcessor', `Connection' and
     `DatabaseMetaData' classes.

   * Escape `0x5c' character in strings for the SJIS charset.

   * `PreparedStatement' now honors stream lengths in
     setBinary/Ascii/Character Stream() unless you set the connection
     property `useStreamLengthsInPrepStmts' to `false'.

   * Fixed issue with updatable result sets and `PreparedStatements'
     not working.

   * Fixed start position off-by-1 error in `Clob.getSubString()'.

   * Added `connectTimeout' parameter that allows users of JDK-1.4 and
     newer to specify a maximum time to wait to establish a connection.

   * Fixed various non-ASCII character encoding issues.

   * Fixed `ResultSet.isLast()' for empty result sets (should return
     `false').

   * Added driver property `useHostsInPrivileges'.  Defaults to `true'.
     Affects whether or not `@hostname' will be used in
     `DBMD.getColumn/TablePrivileges'.

   * Fixed `ResultSet.setFetchDirection(FETCH_UNKNOWN)'.

   * Added `queriesBeforeRetryMaster' property that specifies how many
     queries to issue when failed over before attempting to reconnect
     to the master (defaults to 50).

   * Fixed issue when calling `Statement.setFetchSize()' when using
     arbitrary values.

   * Properly restore connection properties when autoReconnecting or
     failing-over, including `autoCommit' state, and isolation level.

   * Implemented `Clob.truncate()'.


File: manual.info,  Node: cj-news-3-0-1,  Next: cj-news-3-0-0,  Prev: cj-news-3-0-2,  Up: cg-news-3-0

C.5.4.17 Changes in MySQL Connector/J 3.0.1 (21 September 2002)
...............................................................

Bugs fixed:

   * Charsets now automatically detected. Optimized code for
     single-byte character set conversion.

   * Fixed `ResultSetMetaData.isSigned()' for `TINYINT' and `BIGINT'.

   * Fixed `RowDataStatic.getAt()' off-by-one bug.

   * Fixed `ResultSet.getRow()' off-by-one bug.

   * Massive code clean-up to follow Java coding conventions (the time
     had come).

   * Implemented `ResultSet.getCharacterStream()'.

   * Added limited `Clob' functionality (`ResultSet.getClob()',
     `PreparedStatemtent.setClob()',
     `PreparedStatement.setObject(Clob)'.

   * `Connection.isClosed()' no longer `pings' the server.

   * `Connection.close()' issues `rollback()' when `getAutoCommit()' is
     `false'.

   * Added `socketTimeout' parameter to URL.

   * Added `LOCAL TEMPORARY' to table types in
     `DatabaseMetaData.getTableTypes()'.

   * Added `paranoid' parameter, which sanitizes error messages by
     removing `sensitive' information from them (such as hostnames,
     ports, or usernames), as well as clearing `sensitive' data
     structures when possible.


File: manual.info,  Node: cj-news-3-0-0,  Prev: cj-news-3-0-1,  Up: cg-news-3-0

C.5.4.18 Changes in MySQL Connector/J 3.0.0 (31 July 2002)
..........................................................

Bugs fixed:

   * General source-code cleanup.

   * The driver now only works with JDK-1.2 or newer.

   * Fix and sort primary key names in `DBMetaData' (SF bugs 582086 and
     582086).

   * `ResultSet.getTimestamp()' now works for `DATE' types (SF bug
     559134).

   * Float types now reported as `java.sql.Types.FLOAT' (SF bug 579573).

   * Support for streaming (row-by-row) result sets (see `README')
     Thanks to Doron.

   * Testsuite now uses Junit (which you can get from
     `http://www.junit.org'.

   * JDBC Compliance: Passes all tests besides stored procedure tests.

   * `ResultSet.getDate/Time/Timestamp' now recognizes all forms of
     invalid values that have been set to all zeros by MySQL (SF bug
     586058).

   * Added multi-host failover support (see `README').

   * Repackaging: New driver name is `com.mysql.jdbc.Driver', old name
     still works, though (the driver is now provided by MySQL-AB).

   * Support for large packets (new addition to MySQL-4.0 protocol),
     see `README' for more information.

   * Better checking for closed connections in `Statement' and
     `PreparedStatement'.

   * Performance improvements in string handling and field metadata
     creation (lazily instantiated) contributed by Alex
     Twisleton-Wykeham-Fiennes.

   * JDBC-3.0 functionality including
     `Statement/PreparedStatement.getGeneratedKeys()' and
     `ResultSet.getURL()'.

   * Overall speed improvements via controlling transient object
     creation in `MysqlIO' class when reading packets.

   * *!!! LICENSE CHANGE !!!* The driver is now GPL. If you need
     non-GPL licenses, please contact me `<mark@mysql.com>'.

   * Performance enchancements: Driver is now 50-100% faster in most
     situations, and creates fewer temporary objects.


File: manual.info,  Node: cj-news-2-0,  Next: cj-news-1-2b,  Prev: cg-news-3-0,  Up: cj-news

C.5.5 Changes in MySQL Connector/J 2.0.x
----------------------------------------

* Menu:

* cj-news-2-0-14::               Changes in MySQL Connector/J 2.0.14 (16 May 2002)
* cj-news-2-0-13::               Changes in MySQL Connector/J 2.0.13 (24 April 2002)
* cj-news-2-0-12::               Changes in MySQL Connector/J 2.0.12 (07 April 2002)
* cj-news-2-0-11::               Changes in MySQL Connector/J 2.0.11 (27 January 2002)
* cj-news-2-0-10::               Changes in MySQL Connector/J 2.0.10 (24 January 2002)
* cj-news-2-0-9::                Changes in MySQL Connector/J 2.0.9 (13 January 2002)
* cj-news-2-0-8::                Changes in MySQL Connector/J 2.0.8 (25 November 2001)
* cj-news-2-0-7::                Changes in MySQL Connector/J 2.0.7 (24 October 2001)
* cj-news-2-0-6::                Changes in MySQL Connector/J 2.0.6 (16 June 2001)
* cj-news-2-0-5::                Changes in MySQL Connector/J 2.0.5 (13 June 2001)
* cj-news-2-0-3::                Changes in MySQL Connector/J 2.0.3 (03 December 2000)
* cj-news-2-0-1::                Changes in MySQL Connector/J 2.0.1 (06 April 2000)
* cj-news-2-0pre5::              Changes in MySQL Connector/J 2.0.0pre5 (21 February 2000)
* cj-news-2-0pre4::              Changes in MySQL Connector/J 2.0.0pre4 (10 January 2000)
* cj-news-2-0pre::               Changes in MySQL Connector/J 2.0.0pre (17 August 1999)


File: manual.info,  Node: cj-news-2-0-14,  Next: cj-news-2-0-13,  Prev: cj-news-2-0,  Up: cj-news-2-0

C.5.5.1 Changes in MySQL Connector/J 2.0.14 (16 May 2002)
.........................................................

Bugs fixed:

   * `ResultSet.getDouble()' now uses code built into JDK to be more
     precise (but slower).

   * Fixed typo for `relaxAutoCommit' parameter.

   * `LogicalHandle.isClosed()' calls through to physical connection.

   * Added SQL profiling (to `STDERR'). Set `profileSql=true' in your
     JDBC URL. See `README' for more information.

   * `PreparedStatement' now releases resources on `.close()'. (SF bug
     553268)

   * More code cleanup.

   * Quoted identifiers not used if server version does not support
     them. Also, if server started with `--ansi' or
     `--sql-mode=ANSI_QUOTES', ``"'' will be used as an identifier
     quote character, otherwise ``''' will be used.


File: manual.info,  Node: cj-news-2-0-13,  Next: cj-news-2-0-12,  Prev: cj-news-2-0-14,  Up: cj-news-2-0

C.5.5.2 Changes in MySQL Connector/J 2.0.13 (24 April 2002)
...........................................................

Bugs fixed:

   * Fixed unicode chars being read incorrectly. (SF bug 541088)

   * Faster blob escaping for `PrepStmt'.

   * Added `setURL()' to `MySQLXADataSource'. (SF bug 546019)

   * Added `set'/`getPortNumber()' to `DataSource(s)'. (SF bug 548167)

   * `PreparedStatement.toString()' fixed. (SF bug 534026)

   * More code cleanup.

   * Rudimentary version of `Statement.getGeneratedKeys()' from JDBC-3.0
     now implemented (you need to be using JDK-1.4 for this to work, I
     believe).

   * `DBMetaData.getIndexInfo()' - bad PAGES fixed.  (SF BUG 542201)

   * `ResultSetMetaData.getColumnClassName()' now implemented.


File: manual.info,  Node: cj-news-2-0-12,  Next: cj-news-2-0-11,  Prev: cj-news-2-0-13,  Up: cj-news-2-0

C.5.5.3 Changes in MySQL Connector/J 2.0.12 (07 April 2002)
...........................................................

Bugs fixed:

   * Fixed `testsuite.Traversal' `afterLast()' bug, thanks to Igor
     Lastric.

   * Added new types to `getTypeInfo()', fixed existing types thanks to
     Al Davis and Kid Kalanon.

   * Fixed time zone off-by-1-hour bug in `PreparedStatement' (538286,
     528785).

   * Added identifier quoting to all `DatabaseMetaData' methods that
     need them (should fix 518108).

   * Added support for `BIT' types (51870) to `PreparedStatement'.

   * `ResultSet.insertRow()' should now detect auto_increment fields in
     most cases and use that value in the new row. This detection will
     not work in multi-valued keys, however, due to the fact that the
     MySQL protocol does not return this information.

   * Relaxed synchronization in all classes, should fix 520615 and
     520393.

   * `DataSources' - fixed `setUrl' bug (511614, 525565), wrong
     datasource class name (532816, 528767).

   * Added support for `YEAR' type (533556).

   * Fixes for `ResultSet' updatability in `PreparedStatement'.

   * `ResultSet': Fixed updatability (values being set to `null' if not
     updated).

   * Added `getTable/ColumnPrivileges()' to DBMD (fixes 484502).

   * Added `getIdleFor()' method to `Connection' and
     `MysqlLogicalHandle'.

   * `ResultSet.refreshRow()' implemented.

   * Fixed `getRow()' bug (527165) in `ResultSet'.

   * General code cleanup.


File: manual.info,  Node: cj-news-2-0-11,  Next: cj-news-2-0-10,  Prev: cj-news-2-0-12,  Up: cj-news-2-0

C.5.5.4 Changes in MySQL Connector/J 2.0.11 (27 January 2002)
.............................................................

Bugs fixed:

   * Full synchronization of `Statement.java'.

   * Fixed missing `DELETE_RULE' value in
     `DBMD.getImported/ExportedKeys()' and `getCrossReference()'.

   * More changes to fix `Unexpected end of input stream' errors when
     reading `BLOB' values. This should be the last fix.


File: manual.info,  Node: cj-news-2-0-10,  Next: cj-news-2-0-9,  Prev: cj-news-2-0-11,  Up: cj-news-2-0

C.5.5.5 Changes in MySQL Connector/J 2.0.10 (24 January 2002)
.............................................................

Bugs fixed:

   * Fixed null-pointer-exceptions when using
     `MysqlConnectionPoolDataSource' with Websphere 4 (bug 505839).

   * Fixed spurious `Unexpected end of input stream' errors in
     `MysqlIO' (bug 507456).


File: manual.info,  Node: cj-news-2-0-9,  Next: cj-news-2-0-8,  Prev: cj-news-2-0-10,  Up: cj-news-2-0

C.5.5.6 Changes in MySQL Connector/J 2.0.9 (13 January 2002)
............................................................

Bugs fixed:

   * Fixed extra memory allocation in `MysqlIO.readPacket()' (bug
     488663).

   * Added detection of network connection being closed when reading
     packets (thanks to Todd Lizambri).

   * Fixed casting bug in `PreparedStatement' (bug 488663).

   * `DataSource' implementations moved to
     `org.gjt.mm.mysql.jdbc2.optional' package, and (initial)
     implementations of `PooledConnectionDataSource' and `XADataSource'
     are in place (thanks to Todd Wolff for the implementation and
     testing of `PooledConnectionDataSource' with IBM WebSphere 4).

   * Fixed quoting error with escape processor (bug 486265).

   * Removed concatenation support from driver (the `||' operator), as
     older versions of VisualAge seem to be the only thing that use it,
     and it conflicts with the logical `||' operator. You will need to
     start `mysqld' with the `--ansi' flag to use the `||' operator as
     concatenation (bug 491680).

   * `Ant' build was corrupting included `jar' files, fixed (bug
     487669).

   * Report batch update support through `DatabaseMetaData' (bug
     495101).

   * Implementation of `DatabaseMetaData.getExported/ImportedKeys()'
     and `getCrossReference()'.

   * Fixed off-by-one-hour error in `PreparedStatement.setTimestamp()'
     (bug 491577).

   * Full synchronization on methods modifying instance and
     class-shared references, driver should be entirely thread-safe now
     (please let me know if you have problems).


File: manual.info,  Node: cj-news-2-0-8,  Next: cj-news-2-0-7,  Prev: cj-news-2-0-9,  Up: cj-news-2-0

C.5.5.7 Changes in MySQL Connector/J 2.0.8 (25 November 2001)
.............................................................

Bugs fixed:

   * `XADataSource'/`ConnectionPoolDataSource' code (experimental)

   * `DatabaseMetaData.getPrimaryKeys()' and `getBestRowIdentifier()'
     are now more robust in identifying primary keys (matches
     regardless of case or abbreviation/full spelling of `Primary Key'
     in `Key_type' column).

   * Batch updates now supported (thanks to some inspiration from
     Daniel Rall).

   * `PreparedStatement.setAnyNumericType()' now handles positive
     exponents correctly (adds `+' so MySQL can understand it).


File: manual.info,  Node: cj-news-2-0-7,  Next: cj-news-2-0-6,  Prev: cj-news-2-0-8,  Up: cj-news-2-0

C.5.5.8 Changes in MySQL Connector/J 2.0.7 (24 October 2001)
............................................................

Bugs fixed:

   * Character sets read from database if `useUnicode=true' and
     `characterEncoding' is not set. (thanks to Dmitry Vereshchagin)

   * Initial transaction isolation level read from database (if
     avaialable). (thanks to Dmitry Vereshchagin)

   * Fixed `PreparedStatement' generating SQL that would end up with
     syntax errors for some queries.

   * `PreparedStatement.setCharacterStream()' now implemented

   * Captialize type names when `captializeTypeNames=true' is passed in
     URL or properties (for WebObjects. (thanks to Anjo Krank)

   * `ResultSet.getBlob()' now returns `null' if column value was
     `null'.

   * Fixed `ResultSetMetaData.getPrecision()' returning one less than
     actual on newer versions of MySQL.

   * Fixed dangling socket problem when in high availability
     (`autoReconnect=true') mode, and finalizer for `Connection' will
     close any dangling sockets on GC.

   * Fixed time zone issue in `PreparedStatement.setTimestamp()'.
     (thanks to Erik Olofsson)

   * PreparedStatement.setDouble() now uses full-precision doubles
     (reverting a fix made earlier to truncate them).

   * Fixed `DatabaseMetaData.supportsTransactions()', and
     `supportsTransactionIsolationLevel()' and `getTypeInfo()'
     `SQL_DATETIME_SUB' and `SQL_DATA_TYPE' fields not being readable.

   * Updatable result sets now correctly handle `NULL' values in fields.

   * PreparedStatement.setBoolean() will use 1/0 for values if your
     MySQL version is 3.21.23 or higher.

   * Fixed `ResultSet.isAfterLast()' always returning `false'.


File: manual.info,  Node: cj-news-2-0-6,  Next: cj-news-2-0-5,  Prev: cj-news-2-0-7,  Up: cj-news-2-0

C.5.5.9 Changes in MySQL Connector/J 2.0.6 (16 June 2001)
.........................................................

Bugs fixed:

   * Fixed `PreparedStatement' parameter checking.

   * Fixed case-sensitive column names in `ResultSet.java'.


File: manual.info,  Node: cj-news-2-0-5,  Next: cj-news-2-0-3,  Prev: cj-news-2-0-6,  Up: cj-news-2-0

C.5.5.10 Changes in MySQL Connector/J 2.0.5 (13 June 2001)
..........................................................

Bugs fixed:

   * `ResultSet.insertRow()' works now, even if not all columns are set
     (they will be set to `NULL').

   * Added `Byte' to `PreparedStatement.setObject()'.

   * Fixed data parsing of `TIMESTAMP' values with 2-digit years.

   * Added `ISOLATION' level support to `Connection.setIsolationLevel()'

   * `DataBaseMetaData.getCrossReference()' no longer `ArrayIndexOOB'.

   * `ResultSet.getBoolean()' now recognizes `-1' as `true'.

   * `ResultSet' has +/-Inf/inf support.

   * `getObject()' on `ResultSet' correctly does `TINYINT'->`Byte' and
     `SMALLINT'->`Short'.

   * Fixed `ResultSetMetaData.getColumnTypeName' for `TEXT'/`BLOB'.

   * Fixed `ArrayIndexOutOfBounds' when sending large `BLOB' queries.
     (Max size packet was not being set)

   * Fixed NPE on `PreparedStatement.executeUpdate()' when all columns
     have not been set.

   * Fixed `ResultSet.getBlob()' `ArrayIndex' out-of-bounds.


File: manual.info,  Node: cj-news-2-0-3,  Next: cj-news-2-0-1,  Prev: cj-news-2-0-5,  Up: cj-news-2-0

C.5.5.11 Changes in MySQL Connector/J 2.0.3 (03 December 2000)
..............................................................

Bugs fixed:

   * Fixed composite key problem with updatable result sets.

   * Faster ASCII string operations.

   * Fixed off-by-one error in `java.sql.Blob' implementation code.

   * Fixed incorrect detection of `MAX_ALLOWED_PACKET', so sending
     large blobs should work now.

   * Added detection of -/+INF for doubles.

   * Added `ultraDevHack' URL parameter, set to `true' to allow
     (broken) Macromedia UltraDev to use the driver.

   * Implemented `getBigDecimal()' without scale component for JDBC2.


File: manual.info,  Node: cj-news-2-0-1,  Next: cj-news-2-0pre5,  Prev: cj-news-2-0-3,  Up: cj-news-2-0

C.5.5.12 Changes in MySQL Connector/J 2.0.1 (06 April 2000)
...........................................................

Bugs fixed:

   * Columns that are of type `TEXT' now return as `Strings' when you
     use `getObject()'.

   * Cleaned up exception handling when driver connects.

   * Fixed `RSMD.isWritable()' returning wrong value. Thanks to Moritz
     Maass.

   * `DatabaseMetaData.getPrimaryKeys()' now works correctly with
     respect to `key_seq'. Thanks to Brian Slesinsky.

   * Fixed many JDBC-2.0 traversal, positioning bugs, especially with
     respect to empty result sets. Thanks to Ron Smits, Nick Brook,
     Cessar Garcia and Carlos Martinez.

   * No escape processing is done on `PreparedStatements' anymore per
     JDBC spec.

   * Fixed some issues with updatability support in `ResultSet' when
     using multiple primary keys.


File: manual.info,  Node: cj-news-2-0pre5,  Next: cj-news-2-0pre4,  Prev: cj-news-2-0-1,  Up: cj-news-2-0

C.5.5.13 Changes in MySQL Connector/J 2.0.0pre5 (21 February 2000)
..................................................................

   * Fixed Bad Handshake problem.


File: manual.info,  Node: cj-news-2-0pre4,  Next: cj-news-2-0pre,  Prev: cj-news-2-0pre5,  Up: cj-news-2-0

C.5.5.14 Changes in MySQL Connector/J 2.0.0pre4 (10 January 2000)
.................................................................

   * Fixes to ResultSet for insertRow() - Thanks to Cesar Garcia

   * Fix to Driver to recognize JDBC-2.0 by loading a JDBC-2.0 class,
     instead of relying on JDK version numbers. Thanks to John Baker.

   * Fixed ResultSet to return correct row numbers

   * Statement.getUpdateCount() now returns rows matched, instead of
     rows actually updated, which is more SQL-92 like.

10-29-99

   * Statement/PreparedStatement.getMoreResults() bug fixed.  Thanks to
     Noel J. Bergman.

   * Added Short as a type to PreparedStatement.setObject().  Thanks to
     Jeff Crowder

   * Driver now automagically configures maximum/preferred packet sizes
     by querying server.

   * Autoreconnect code uses fast ping command if server supports it.

   * Fixed various bugs with respect to packet sizing when reading from
     the server and when alloc'ing to write to the server.


File: manual.info,  Node: cj-news-2-0pre,  Prev: cj-news-2-0pre4,  Up: cj-news-2-0

C.5.5.15 Changes in MySQL Connector/J 2.0.0pre (17 August 1999)
...............................................................

   * Now compiles under JDK-1.2. The driver supports both JDK-1.1 and
     JDK-1.2 at the same time through a core set of classes.  The
     driver will load the appropriate interface classes at runtime by
     figuring out which JVM version you are using.

   * Fixes for result sets with all nulls in the first row.  (Pointed
     out by Tim Endres)

   * Fixes to column numbers in SQLExceptions in ResultSet (Thanks to
     Blas Rodriguez Somoza)

   * The database no longer needs to specified to connect.  (Thanks to
     Christian Motschke)


File: manual.info,  Node: cj-news-1-2b,  Next: cg-news-1-0,  Prev: cj-news-2-0,  Up: cj-news

C.5.6 Changes in MySQL Connector/J 1.2b (04 July 1999)
------------------------------------------------------

   * Better Documentation (in progress), in doc/mm.doc/book1.html

   * DBMD now allows null for a column name pattern (not in spec),
     which it changes to '%'.

   * DBMD now has correct types/lengths for getXXX().

   * ResultSet.getDate(), getTime(), and getTimestamp() fixes.
     (contributed by Alan Wilken)

   * EscapeProcessor now handles \{ \} and { or } inside quotes
     correctly. (thanks to Alik for some ideas on how to fix it)

   * Fixes to properties handling in Connection. (contributed by Juho
     Tikkala)

   * ResultSet.getObject() now returns null for NULL columns in the
     table, rather than bombing out. (thanks to Ben Grosman)

   * ResultSet.getObject() now returns Strings for types from MySQL
     that it doesn't know about. (Suggested by Chris Perdue)

   * Removed DataInput/Output streams, not needed, 1/2 number of method
     calls per IO operation.

   * Use default character encoding if one is not specified. This is a
     work-around for broken JVMs, because according to spec, EVERY JVM
     must support "ISO8859_1", but they don't.

   * Fixed Connection to use the platform character encoding instead of
     "ISO8859_1" if one isn't explicitly set. This fixes problems
     people were having loading the character- converter classes that
     didn't always exist (JVM bug). (thanks to Fritz Elfert for
     pointing out this problem)

   * Changed MysqlIO to re-use packets where possible to reduce memory
     usage.

   * Fixed escape-processor bugs pertaining to {} inside quotes.


File: manual.info,  Node: cg-news-1-0,  Prev: cj-news-1-2b,  Up: cj-news

C.5.7 Changes in MySQL Connector/J 1.2.x and lower
--------------------------------------------------

* Menu:

* cj-news-1-2a::                 Changes in MySQL Connector/J 1.2a (14 April 1999)
* cj-news-1-1i::                 Changes in MySQL Connector/J 1.1i (24 March 1999)
* cj-news-1-1h::                 Changes in MySQL Connector/J 1.1h (08 March 1999)
* cj-news-1-1g::                 Changes in MySQL Connector/J 1.1g (19 February 1999)
* cj-news-1-1f::                 Changes in MySQL Connector/J 1.1f (31 December 1998)
* cj-news-1-1b::                 Changes in MySQL Connector/J 1.1b (03 November 1998)
* cj-news-1-1::                  Changes in MySQL Connector/J 1.1 (02 September 1998)
* cj-news-1-0::                  Changes in MySQL Connector/J 1.0 (24 August 1998)
* cj-news-0-9d::                 Changes in MySQL Connector/J 0.9d (04 August 1998)
* cj-news-0-9::                  Changes in MySQL Connector/J 0.9 (28 July 1998)
* cj-news-0-8::                  Changes in MySQL Connector/J 0.8 (06 July 1998)
* cj-news-0-7::                  Changes in MySQL Connector/J 0.7 (01 July 1998)
* cj-news-0-6::                  Changes in MySQL Connector/J 0.6 (21 May 1998)


File: manual.info,  Node: cj-news-1-2a,  Next: cj-news-1-1i,  Prev: cg-news-1-0,  Up: cg-news-1-0

C.5.7.1 Changes in MySQL Connector/J 1.2a (14 April 1999)
.........................................................

   * Fixed character-set support for non-Javasoft JVMs (thanks to many
     people for pointing it out)

   * Fixed ResultSet.getBoolean() to recognize 'y' & 'n' as well as '1'
     & '0' as boolean flags. (thanks to Tim Pizey)

   * Fixed ResultSet.getTimestamp() to give better performance.
     (thanks to Richard Swift)

   * Fixed getByte() for numeric types. (thanks to Ray Bellis)

   * Fixed DatabaseMetaData.getTypeInfo() for DATE type. (thanks to
     Paul Johnston)

   * Fixed EscapeProcessor for "fn" calls. (thanks to Piyush Shah at
     locomotive.org)

   * Fixed EscapeProcessor to not do extraneous work if there are no
     escape codes. (thanks to Ryan Gustafson)

   * Fixed Driver to parse URLs of the form "jdbc:mysql://host:port"
     (thanks to Richard Lobb)


File: manual.info,  Node: cj-news-1-1i,  Next: cj-news-1-1h,  Prev: cj-news-1-2a,  Up: cg-news-1-0

C.5.7.2 Changes in MySQL Connector/J 1.1i (24 March 1999)
.........................................................

   * Fixed Timestamps for PreparedStatements

   * Fixed null pointer exceptions in RSMD and RS

   * Re-compiled with jikes for valid class files (thanks ms!)


File: manual.info,  Node: cj-news-1-1h,  Next: cj-news-1-1g,  Prev: cj-news-1-1i,  Up: cg-news-1-0

C.5.7.3 Changes in MySQL Connector/J 1.1h (08 March 1999)
.........................................................

   * Fixed escape processor to deal with unmatched { and } (thanks to
     Craig Coles)

   * Fixed escape processor to create more portable (between DATETIME
     and TIMESTAMP types) representations so that it will work with
     BETWEEN clauses. (thanks to Craig Longman)

   * MysqlIO.quit() now closes the socket connection. Before, after
     many failed connections some OS's would run out of file
     descriptors. (thanks to Michael Brinkman)

   * Fixed NullPointerException in Driver.getPropertyInfo.  (thanks to
     Dave Potts)

   * Fixes to MysqlDefs to allow all *text fields to be retrieved as
     Strings. (thanks to Chris at Leverage)

   * Fixed setDouble in PreparedStatement for large numbers to avoid
     sending scientific notation to the database. (thanks to J.S.
     Ferguson)

   * Fixed getScale() and getPrecision() in RSMD. (contrib'd by James
     Klicman)

   * Fixed getObject() when field was DECIMAL or NUMERIC (thanks to
     Bert Hobbs)

   * DBMD.getTables() bombed when passed a null table-name pattern.
     Fixed. (thanks to Richard Lobb)

   * Added check for "client not authorized" errors during connect.
     (thanks to Hannes Wallnoefer)


File: manual.info,  Node: cj-news-1-1g,  Next: cj-news-1-1f,  Prev: cj-news-1-1h,  Up: cg-news-1-0

C.5.7.4 Changes in MySQL Connector/J 1.1g (19 February 1999)
............................................................

   * Result set rows are now byte arrays. Blobs and Unicode work
     bidriectonally now. The useUnicode and encoding options are
     implemented now.

   * Fixes to PreparedStatement to send binary set by setXXXStream to
     be sent untouched to the MySQL server.

   * Fixes to getDriverPropertyInfo().


File: manual.info,  Node: cj-news-1-1f,  Next: cj-news-1-1b,  Prev: cj-news-1-1g,  Up: cg-news-1-0

C.5.7.5 Changes in MySQL Connector/J 1.1f (31 December 1998)
............................................................

   * Changed all ResultSet fields to Strings, this should allow Unicode
     to work, but your JVM must be able to convert between the
     character sets. This should also make reading data from the server
     be a bit quicker, because there is now no conversion from
     StringBuffer to String.

   * Changed PreparedStatement.streamToString() to be more efficient
     (code from Uwe Schaefer).

   * URL parsing is more robust (throws SQL exceptions on errors rather
     than NullPointerExceptions)

   * PreparedStatement now can convert Strings to Time/Date values via
     setObject() (code from Robert Currey).

   * IO no longer hangs in Buffer.readInt(), that bug was introduced in
     1.1d when changing to all byte-arrays for result sets. (Pointed
     out by Samo Login)


File: manual.info,  Node: cj-news-1-1b,  Next: cj-news-1-1,  Prev: cj-news-1-1f,  Up: cg-news-1-0

C.5.7.6 Changes in MySQL Connector/J 1.1b (03 November 1998)
............................................................

   * Fixes to DatabaseMetaData to allow both IBM VA and J-Builder to
     work. Let me know how it goes. (thanks to Jac Kersing)

   * Fix to ResultSet.getBoolean() for NULL strings (thanks to Barry
     Lagerweij)

   * Beginning of code cleanup, and formatting. Getting ready to branch
     this off to a parallel JDBC-2.0 source tree.

   * Added "final" modifier to critical sections in MysqlIO and Buffer
     to allow compiler to inline methods for speed.

9-29-98

   * If object references passed to setXXX() in PreparedStatement are
     null, setNull() is automatically called for you. (Thanks for the
     suggestion goes to Erik Ostrom)

   * setObject() in PreparedStatement will now attempt to write a
     serialized representation of the object to the database for
     objects of Types.OTHER and objects of unknown type.

   * Util now has a static method readObject() which given a ResultSet
     and a column index will re-instantiate an object serialized in the
     above manner.


File: manual.info,  Node: cj-news-1-1,  Next: cj-news-1-0,  Prev: cj-news-1-1b,  Up: cg-news-1-0

C.5.7.7 Changes in MySQL Connector/J 1.1 (02 September 1998)
............................................................

   * Got rid of "ugly hack" in MysqlIO.nextRow(). Rather than catch an
     exception, Buffer.isLastDataPacket() was fixed.

   * Connection.getCatalog() and Connection.setCatalog() should work
     now.

   * Statement.setMaxRows() works, as well as setting by property
     maxRows. Statement.setMaxRows() overrides maxRows set via
     properties or url parameters.

   * Automatic re-connection is available. Because it has to "ping" the
     database before each query, it is turned off by default. To use
     it, pass in "autoReconnect=true" in the connection URL. You may
     also change the number of reconnect tries, and the initial timeout
     value via "maxReconnects=n" (default 3) and "initialTimeout=n"
     (seconds, default 2) parameters. The timeout is an exponential
     backoff type of timeout; for example, if you have initial timeout
     of 2 seconds, and maxReconnects of 3, then the driver will timeout
     2 seconds, 4 seconds, then 16 seconds between each re-connection
     attempt.


File: manual.info,  Node: cj-news-1-0,  Next: cj-news-0-9d,  Prev: cj-news-1-1,  Up: cg-news-1-0

C.5.7.8 Changes in MySQL Connector/J 1.0 (24 August 1998)
.........................................................

   * Fixed handling of blob data in Buffer.java

   * Fixed bug with authentication packet being sized too small.

   * The JDBC Driver is now under the LPGL

8-14-98

   * Fixed Buffer.readLenString() to correctly read data for BLOBS.

   * Fixed PreparedStatement.stringToStream to correctly read data for
     BLOBS.

   * Fixed PreparedStatement.setDate() to not add a day. (above fixes
     thanks to Vincent Partington)

   * Added URL parameter parsing (?user=... and so forth).


File: manual.info,  Node: cj-news-0-9d,  Next: cj-news-0-9,  Prev: cj-news-1-0,  Up: cg-news-1-0

C.5.7.9 Changes in MySQL Connector/J 0.9d (04 August 1998)
..........................................................

   * Big news! New package name. Tim Endres from ICE Engineering is
     starting a new source tree for GNU GPL'd Java software.  He's
     graciously given me the org.gjt.mm package directory to use, so
     now the driver is in the org.gjt.mm.mysql package scheme. I'm
     "legal" now. Look for more information on Tim's project soon.

   * Now using dynamically sized packets to reduce memory usage when
     sending commands to the DB.

   * Small fixes to getTypeInfo() for parameters, and so forth.

   * DatabaseMetaData is now fully implemented. Let me know if these
     drivers work with the various IDEs out there. I've heard that
     they're working with JBuilder right now.

   * Added JavaDoc documentation to the package.

   * Package now available in .zip or .tar.gz.


File: manual.info,  Node: cj-news-0-9,  Next: cj-news-0-8,  Prev: cj-news-0-9d,  Up: cg-news-1-0

C.5.7.10 Changes in MySQL Connector/J 0.9 (28 July 1998)
........................................................

   * Implemented getTypeInfo(). Connection.rollback() now throws an
     SQLException per the JDBC spec.

   * Added PreparedStatement that supports all JDBC API methods for
     PreparedStatement including InputStreams. Please check this out
     and let me know if anything is broken.

   * Fixed a bug in ResultSet that would break some queries that only
     returned 1 row.

   * Fixed bugs in DatabaseMetaData.getTables(),
     DatabaseMetaData.getColumns() and DatabaseMetaData.getCatalogs().

   * Added functionality to Statement that allows executeUpdate() to
     store values for IDs that are automatically generated for
     AUTO_INCREMENT fields. Basically, after an executeUpdate(), look
     at the SQLWarnings for warnings like "LAST_INSERTED_ID = 'some
     number', COMMAND = 'your SQL query'". If you are using
     AUTO_INCREMENT fields in your tables and are executing a lot of
     executeUpdate()s on one Statement, be sure to clearWarnings()
     every so often to save memory.


File: manual.info,  Node: cj-news-0-8,  Next: cj-news-0-7,  Prev: cj-news-0-9,  Up: cg-news-1-0

C.5.7.11 Changes in MySQL Connector/J 0.8 (06 July 1998)
........................................................

   * Split MysqlIO and Buffer to separate classes. Some ClassLoaders
     gave an IllegalAccess error for some fields in those two classes.
     Now mm.mysql works in applets and all classloaders. Thanks to Joe
     Ennis <jce@mail.boone.com> for pointing out the problem and
     working on a fix with me.


File: manual.info,  Node: cj-news-0-7,  Next: cj-news-0-6,  Prev: cj-news-0-8,  Up: cg-news-1-0

C.5.7.12 Changes in MySQL Connector/J 0.7 (01 July 1998)
........................................................

   * Fixed DatabaseMetadata problems in getColumns() and bug in switch
     statement in the Field constructor. Thanks to Costin Manolache
     <costin@tdiinc.com> for pointing these out.


File: manual.info,  Node: cj-news-0-6,  Prev: cj-news-0-7,  Up: cg-news-1-0

C.5.7.13 Changes in MySQL Connector/J 0.6 (21 May 1998)
.......................................................

   * Incorporated efficiency changes from Richard Swift
     <Richard.Swift@kanatek.ca> in `MysqlIO.java' and `ResultSet.java':

   * We're now 15% faster than gwe's driver.

   * Started working on `DatabaseMetaData'.

   * The following methods are implemented:

        * `getTables()'

        * `getTableTypes()'

        * `getColumns()'

        * `getCatalogs()'


File: manual.info,  Node: news-connector-mxj,  Next: mysql-proxy-news,  Prev: cj-news,  Up: news

C.6 MySQL Connector/MXJ Change History
======================================

* Menu:

* news-connector-mxj-5-0-6::     Changes in MySQL Connector/MXJ 5.0.6 (04 May 2007)
* news-connector-mxj-5-0-5::     Changes in MySQL Connector/MXJ 5.0.5 (14 March 2007)
* news-connector-mxj-5-0-4::     Changes in MySQL Connector/MXJ 5.0.4 (28 January 2007)
* news-connector-mxj-5-0-3::     Changes in MySQL Connector/MXJ 5.0.3 (24 June 2006)
* news-connector-mxj-5-0-2::     Changes in MySQL Connector/MXJ 5.0.2 (15 June 2006)
* news-connector-mxj-5-0-1::     Changes in MySQL Connector/MXJ 5.0.1 (Never released)
* news-connector-mxj-5-0-0::     Changes in MySQL Connector/MXJ 5.0.0 (09 December 2005)


File: manual.info,  Node: news-connector-mxj-5-0-6,  Next: news-connector-mxj-5-0-5,  Prev: news-connector-mxj,  Up: news-connector-mxj

C.6.1 Changes in MySQL Connector/MXJ 5.0.6 (04 May 2007)
--------------------------------------------------------

Functionality added or changed:

   * Updated internal jar file names to include version information and
     be more consistent with Connector/J jar naming. For example,
     `connector-mxj.jar' is now
     `mysql-connector-mxj-${mxj-version}.jar'.

   * Updated commercial license files.

   * Added copyright notices to some classes which were missing them.

   * Added InitializeUser and QueryUtil classes to support new feature.

   * Added new tests for initial-user & expanded some existing tests.

   * ConnectorMXJUrlTestExample and ConnectorMXJObjectTestExample now
     demonstrate the initialization of user/password and creating the
     initial database (rather than using "test").

   * Added new connection property `initialize-user' which, if set to
     `true' will remove the default, un-passworded anonymous and root
     users, and create the user/password from the connection url.

   * Removed obsolete field `SimpleMysqldDynamicMBean.lastInvocation'.

   * Clarified code in `DefaultsMap.entrySet()'.

   * Removed obsolete `PatchedStandardSocketFactory' java file.

   * Added `main(String[])' to
     `com/mysql/management/AllTestsSuite.java'.

   * Errors reading `portFile' are now reported using
     `stacktrace(err)', previously `System.err' was used.

   * `portFile' now contains a new-line to be consistent with `pidFile'.

   * Fixed where versionString.trim() was ignored.

   * Removed references to File.deleteOnExit, a warning is printed
     instead.

Bugs fixed:

   * Changed tests to shutdown mysqld prior to deleting files.

   * Fixed port file to always be writen to datadir.

   * Added os.name-os.arch to resource directory mapping properties
     file.

   * Swapped out commercial binaries for v5.0.40.

   * Delete `portFile' on shutdown.

   * Moved `platform-map.properties' into `db-files.jar'.

   * Clarified the startup max wait numbers.

   * Updated `build.xml' in preperation for next beta build.

   * Removed `use-default-architecture' property replaced.

   * Added null-check to deal with C/MXJ being loaded by the bootstrap
     classloaders with JVMs for which `getClassLoader()' returns null.

   * Added robustness around reading portfile.

   * Removed `PatchedStandardSocketFactory' (fixed in Connetor/J 5.0.6).

   * Refactored duplication from tests and examples to QueryUtil.

   * Removed obsolete InitializePasswordExample


File: manual.info,  Node: news-connector-mxj-5-0-5,  Next: news-connector-mxj-5-0-4,  Prev: news-connector-mxj-5-0-6,  Up: news-connector-mxj

C.6.2 Changes in MySQL Connector/MXJ 5.0.5 (14 March 2007)
----------------------------------------------------------

Bugs fixed:

   * Moved `MysqldFactory' to main package.

   * Reformatting: Added newlines some files which did not end in them.

   * Swapped out commercial binaries for v5.0.36.

   * Found and removed dynamic linking in mysql_kill; updated solution.

   * Changed protected constructor of `SimpleMysqldDynamicMBean' from
     taking a `MysqldResource' to taking a `MysqldFactory', in order to
     lay groundwork for addressing BUG discovered by Andrew Rubinger.
     See: 143046#msg-143046MySQL Forums (Actual testing with JBoss, and
     filing a bug, is still required.)

   * `build.xml': `usage' now slightly more verbose; some reformatting.

   * Now incoporates Reggie Bernett's `SafeTerminateProcess' and only
     calls the unsafe TerminateProcess as a final last resort.

   * New windows `kill.exe' fixes bug where mysqld was being force
     terminated. Issue reported by bruno haleblian and others, see:
     140623#msg-140623MySQL Forums.

   * Replaced `Boolean.parseBoolean' with JDK 1.4 compliant `valueOf'.

   * Changed `connector-mxj.properties' default mysql version to 5.0.37.

   * In testing so far mysqld reliably shuts down cleanly much faster.

   * Added testcase to `com.mysql.management.jmx.AcceptanceTest' which
     demonstrats that `dataDir' is a mutable MBean property.

   * Updated `build.xml' in prep for next release.

   * Changed `SimpleMysqldDynamicMBean' to create `MysqldResource' on
     demand in order to allow setting of `datadir'. (Rubinger bug
     groundwork).

   * Clarified the synchronization of `MysqldResource' methods.

   * `SIGHUP' is replaced with `MySQLShutdown<PID>' event.

   * Clarified the immutability of `baseDir', `dataDir', `pidFile',
     `portFile'.

   * Added 5.1.15 binaries to the repository.

   * Removed 5.1.14 binaries from the repository.

   * Added `getDataDir()' to interface `MysqldResourceI'.

   * Added 5.1.14 binaries to repository.

   * Replaced windows `kill.exe' resource with re-written version
     specific to mysqld.

   * Added Patched `StandardSocketFactory' from Connector/J 5-0 HEAD.

   * Ensured 5.1.14 compatibility.

   * Swapped out gpl binaries for v5.0.37.

   * Removed 5.0.22 binaries from the repository.


File: manual.info,  Node: news-connector-mxj-5-0-4,  Next: news-connector-mxj-5-0-3,  Prev: news-connector-mxj-5-0-5,  Up: news-connector-mxj

C.6.3 Changes in MySQL Connector/MXJ 5.0.4 (28 January 2007)
------------------------------------------------------------

Bugs fixed:

   * Allow multiple calls to start server from URL connection on
     non-3306 port.  (Bug#24004 (http://bugs.mysql.com/24004))

   * Updated `build.xml' to build to handle with different gpl and
     commercial mysld version numbers.

   * Only populate the options map from the help text if specifically
     requested or in the MBean case.

   * Introduced property for Linux & WinXX to default to 32bit versions.

   * Swapped out gpl binaries for v5.0.27.

   * Swapped out commercial binaries for v5.0.32.

   * Moved mysqld binary resourced into separate jar file NOTICE:
     `CLASSPATH' will now need to `connector-mxj-db-files.jar'.

   * Minor test robustness improvements.

   * Moved default version string out of java class into a text
     editable properties file (`connector-mxj.properties') in the
     resources directory.

   * Fixed test to be tollerant of `/tmp' being a symlink to `/foo/tmp'.


File: manual.info,  Node: news-connector-mxj-5-0-3,  Next: news-connector-mxj-5-0-2,  Prev: news-connector-mxj-5-0-4,  Up: news-connector-mxj

C.6.4 Changes in MySQL Connector/MXJ 5.0.3 (24 June 2006)
---------------------------------------------------------

Bugs fixed:

   * Removed unused imports, formatted code, made minor edits to tests.

   * Removed "TeeOutputStream" - no longer needed.

   * Swapped out the mysqld binaries for MySQL v5.0.22.


File: manual.info,  Node: news-connector-mxj-5-0-2,  Next: news-connector-mxj-5-0-1,  Prev: news-connector-mxj-5-0-3,  Up: news-connector-mxj

C.6.5 Changes in MySQL Connector/MXJ 5.0.2 (15 June 2006)
---------------------------------------------------------

Bugs fixed:

   * Replaced string parsing with JDBC connection attempt for
     determining if a mysqld is "ready for connections" `CLASSPATH'
     will now need to include Connector/J jar.

   * "platform" directories replace spaces with underscores

   * extracted array and list printing to ListToString utility class

   * Swapped out the mysqld binaries for MySQL v5.0.21

   * Added trace level logging with Aspect/J.  `CLASSPATH' will now
     need to include `lib/aspectjrt.jar'

   * reformatted code

   * altered to be "basedir" rather than "port" oriented.

   * help parsing test reflects current help options

   * insulated users from problems with "." in basedir

   * swapped out the mysqld binaries for MySQL v5.0.18

   * Made tests more robust be deleting the /tmp/test-c.mxj directory
     before running tests.

   * ServerLauncherSocketFactory.shutdown API change: now takes File
     parameter (basedir) instead of port.

   * socket is now "mysql.sock" in datadir

   * added ability to specify "mysql-version" as an url parameter

   * Extended timeout for help string parsing, to avoid cases where the
     help text was getting prematurely flushed, and thus truncated.

   * swapped out the mysqld binaries for MySQL v5.0.19

   * MysqldResource now tied to dataDir as well as basedir (API CHANGE)

   * moved PID file into datadir

   * ServerLauncherSocketFactory.shutdown now works across JVMs.

   * extracted splitLines(String) to Str utility class

   * ServerLauncherSocketFactory.shutdown(port) no longer throws, only
     reports to System.err

   * ServerLauncherSocketFactory now treats URL parameters in the form
     of `&server.foo=null' as `serverOptionMap.put("foo", null)'

   * ServerLauncherSocketFactory.shutdown API change: now takes 2 File
     parameters (basedir, datadir)


File: manual.info,  Node: news-connector-mxj-5-0-1,  Next: news-connector-mxj-5-0-0,  Prev: news-connector-mxj-5-0-2,  Up: news-connector-mxj

C.6.6 Changes in MySQL Connector/MXJ 5.0.1 (Never released)
-----------------------------------------------------------

This was an internal only release.


File: manual.info,  Node: news-connector-mxj-5-0-0,  Prev: news-connector-mxj-5-0-1,  Up: news-connector-mxj

C.6.7 Changes in MySQL Connector/MXJ 5.0.0 (09 December 2005)
-------------------------------------------------------------

Bugs fixed:

   * Removed HelpOptionsParser's need to reference a MysqldResource.

   * Reorganized utils into a single "Utils" collaborator.

   * Minor test tweaks

   * Altered examples and tests to use new Connector/J 5.0 URL syntax
     for for launching Connector/MXJ ("jdbc:mysql:mxj://")

   * Swapped out the mysqld binaries for MySQL v5.0.16.

   * Ditched "ClassUtil" (merged with Str).

   * Minor refactorings for type casting and exception handling.


File: manual.info,  Node: mysql-proxy-news,  Prev: news-connector-mxj,  Up: news

C.7 MySQL Proxy Change History
==============================

* Menu:

* mysql-proxy-news-0-6-0::       Changes in MySQL Proxy 0.6.0 (Not yet released)
* mysql-proxy-news-0-5-1::       Changes in MySQL Proxy 0.5.1 (30 June 2007)
* mysql-proxy-news-0-5-0::       Changes in MySQL Proxy 0.5.0 (19 June 2007)


File: manual.info,  Node: mysql-proxy-news-0-6-0,  Next: mysql-proxy-news-0-5-1,  Prev: mysql-proxy-news,  Up: mysql-proxy-news

C.7.1 Changes in MySQL Proxy 0.6.0 (Not yet released)
-----------------------------------------------------

Functionality added or changed:

   * When using read/write splitting and the `rw-splitting.lua' example
     script, connecting a second user to the proxy returns an error
     message.  (Bug#30867 (http://bugs.mysql.com/30867))

   * Added support in `read_query_result()' to overwrite the result-set.

   * Added `--no-daemon' and `--pid-file'.

   * Added hooks for `read_auth()', `read_handshake()' and
     `read_auth_result()'.

   * Added handling of `proxy.connection.backend_ndx' in
     `connect_server()' and `read_query()' to support read/write
     splitting.

   * Added support for `proxy.response.packets'.

   * Added testcases.

   * Added `--no-proxy' to disable the proxy.

   * Added support for listening UNIX sockets.

   * Added a global lua-scope `proxy.global.*'.

   * Added connection pooling.

Bugs fixed:

   * Fixed assertion on `COM_BINLOG_DUMP'.  (Bug#29764
     (http://bugs.mysql.com/29764))

   * Fixed assertion on result-packets like `[ field-len | fields | EOF
     | ERR ]'.  (Bug#29732 (http://bugs.mysql.com/29732))

   * Fixed assertion at login with empty password + empty default db.
     (Bug#29719 (http://bugs.mysql.com/29719))

   * Fixed assertion at `COM_SHUTDOWN'.  (Bug#29719
     (http://bugs.mysql.com/29719))

   * Fixed crash if `proxy.connection' is used in `connect_server()'.

   * Fixed check for `glib2' to require at least 2.6.0.

   * Fixed assertion when all backends are down and we try to connect.

   * Fixed connection-stalling if `read_query_result()' throws an
     `assert()'ion.

   * Fixed len-encoding on `proxy.resulsets'.

   * Fixed compilation on win32.

   * Fixed assertion when connecting to the MySQL 6.0.1.

   * Fixed decoding of len-encoded ints for 3-byte notation.

   * Fixed `inj.resultset.affected_rows' on `SELECT' queries.

   * Fixed handling of (SQL) `NULL' in result-sets.

   * Fixed mem-leak with `proxy.response.*' is used.


File: manual.info,  Node: mysql-proxy-news-0-5-1,  Next: mysql-proxy-news-0-5-0,  Prev: mysql-proxy-news-0-6-0,  Up: mysql-proxy-news

C.7.2 Changes in MySQL Proxy 0.5.1 (30 June 2007)
-------------------------------------------------

Functionality added or changed:

   * Added `resultset.affected_rows' and `resultset.insert_id'.

   * Changed `--proxy.profiling' to `--proxy-skip-profiling'.

   * Added missing dependency to `libmysqlclient-dev' to the INSTALL
     file.

   * Added `inj.query_time' and `inj.response_time' into the lua
     scripts.

   * Added support for pre-4.1 passwords in a 4.1 connection.

   * Added script examples for rewriting and injection.

   * Added `proxy.VERSION'.

   * Added support for UNIX sockets.

   * Added protection against duplicate resultsets from a script.

Bugs fixed:

   * Fixed mysql check in configure to die when mysql.h isn't detected.

   * Fixed handling of duplicate ERR on `COM_CHANGE_USER' in MySQL
     5.1.18+.

   * Fixed compile error with MySQL 4.1.x on missing COM_STMT_*.

   * Fixed crash on fields > 250 bytes when the resultset is inspected.

   * Fixed warning if `connect_server()' is not provided.

   * Fixed assertion when a error occurs at initial script exec time.

   * Fixed assertion when `read_query_result()' is not provided when
     `PROXY_SEND_QUERY' is used.


File: manual.info,  Node: mysql-proxy-news-0-5-0,  Prev: mysql-proxy-news-0-5-1,  Up: mysql-proxy-news

C.7.3 Changes in MySQL Proxy 0.5.0 (19 June 2007)
-------------------------------------------------

This is the first beta release.

Bugs fixed:

   * Added `automake'/`autoconf' support.

   * Added `cmake' support.


File: manual.info,  Node: restrictions,  Next: credits,  Prev: news,  Up: Top

Appendix D Restrictions and Limits
**********************************

* Menu:

* routine-restrictions::         Restrictions on Stored Routines, Triggers, and Events
* cursor-restrictions::          Restrictions on Server-Side Cursors
* subquery-restrictions::        Restrictions on Subqueries
* view-restrictions::            Restrictions on Views
* xa-restrictions::              Restrictions on XA Transactions
* charset-restrictions::         Restrictions on Character Sets
* limits::                       Limits in MySQL

The discussion here describes restrictions that apply to the use of
MySQL features such as subqueries or views.


File: manual.info,  Node: routine-restrictions,  Next: cursor-restrictions,  Prev: restrictions,  Up: restrictions

D.1 Restrictions on Stored Routines, Triggers, and Events
=========================================================

Some of the restrictions noted here apply to all stored routines; that
is, both to stored procedures and stored functions. Some of these
restrictions apply only to stored functions, and not to stored
procedures.

All of the restrictions for stored functions also apply to triggers.

All of the restrictions for stored procedures also apply to the `DO'
clause of event definitions. For additional event-related restrictions,
see *Note events-limitations-restrictions::.

Stored routines cannot contain arbitrary SQL statements. The following
statements are disallowed:

   * The locking statements `LOCK TABLES', `UNLOCK TABLES'.

   * `ALTER VIEW'. (Before MySQL 5.1.21, this restriction is enforced
     only for stored functions.)

   * `LOAD DATA' and `LOAD TABLE'.

   * SQL prepared statements (`PREPARE', `EXECUTE', `DEALLOCATE
     PREPARE') can be used in stored procedures, but not stored
     functions or triggers. Implication: You cannot use dynamic SQL
     within stored functions or triggers (where you construct
     dynamically statements as strings and then execute them).

     In addition, SQL statements that are not permitted within prepared
     statements are also not permitted in stored routines.  See *Note
     sql-syntax-prepared-statements::, for a list of statements
     supported in prepared statements.  Statements not listed there are
     not supported for SQL prepared statements and thus are also not
     supported for stored routines unless noted otherwise in *Note
     stored-procedures::.

   * Inserts cannot be delayed. `INSERT DELAYED' syntax is accepted but
     the statement is handled as a normal `INSERT'.

For stored functions (but not stored procedures), the following
additional statements or operations are disallowed:

   * Statements that do explicit or implicit commit or rollback.

   * Statements that return a result set. This includes `SELECT'
     statements that do not have an `INTO VAR_LIST' clause and `SHOW'
     statements. A function can process a result set either with
     `SELECT ... INTO VAR_LIST' or by using a cursor and `FETCH'
     statements. See *Note select-into-statement::.

   * `FLUSH' statements.

   * Recursive statements. That is, stored functions cannot be used
     recursively.

   * Within a stored function or trigger, it is not permitted to modify
     a table that is already being used (for reading or writing) by the
     statement that invoked the function or trigger.

   * If you refer to a temporary table multiple times in a stored
     function under different aliases, a `Can't reopen table:
     'TBL_NAME`''' error occurs, even if the references occur in
     different statements within the function.

   * A stored function acquires table locks before executing, to avoid
     inconsistency in the binary log due to mismatch of the order in
     which statements execute and when they appear in the log. When
     statement-based binary logging is used, statements that invoke a
     function are recorded rather than the statements executed within
     the function. Consequently, stored functions that update the same
     underlying tables do not execute in parallel.

     In contrast, stored procedures do not acquire table-level locks.
     All statements executed within stored procedures are written to
     the binary log even for statement-based binary logging.

Note that although some restrictions normally apply to stored functions
and triggers but not to stored procedures, those restrictions do apply
to stored procedures if they are invoked from within a stored function
or trigger. For example, although you can use `FLUSH' in a stored
procedure, such a stored procedure cannot be called from a stored
function or trigger.

It is possible for the same identifier to be used for a routine
parameter, a local variable, and a table column. Also, the same local
variable name can be used in nested blocks. For example:

     CREATE PROCEDURE p (i INT)
     BEGIN
       DECLARE i INT DEFAULT 0;
       SELECT i FROM t;
       BEGIN
         DECLARE i INT DEFAULT 1;
         SELECT i FROM t;
       END;
     END;

In such cases the identifier is ambiguous and the following precedence
rules apply:

   * A local variable takes precedence over a routine parameter or
     table column

   * A routine parameter takes precedence over a table column

   * A local variable in an inner block takes precedence over a local
     variable in an outer block

The behavior that variables take precedence over table columns is
non-standard.

Use of stored routines can cause replication problems. This issue is
discussed further in *Note stored-procedure-logging::.

`INFORMATION_SCHEMA' does not have a `PARAMETERS' table until MySQL
6.0, so applications that need to acquire routine parameter information
at runtime must use workarounds such as parsing the output of `SHOW
CREATE' statements or the `param_list' column of the `mysql.proc'
table. `param_list' contents can be processed from within a stored
routine, unlike the output from `SHOW'.

There are no stored routine debugging facilities.

Before MySQL 5.1.4, `CALL' statements cannot be prepared. This true
both for server-side prepared statements and for SQL prepared
statements.

`UNDO' handlers are not supported.

`FOR' loops are not supported.

To prevent problems of interaction between server threads, when a
client issues a statement, the server uses a snapshot of routines and
triggers available for execution of the statement. That is, the server
calculates a list of procedures, functions, and triggers that may be
used during execution of the statement, loads them, and then proceeds
to execute the statement. This means that while the statement executes,
it will not see changes to routines performed by other threads.

For triggers, the following additional statements or operations are
disallowed:

   * Triggers currently are not activated by foreign key actions.

   * The `RETURN' statement is disallowed in triggers, which cannot
     return a value. To exit a trigger immediately, use the `LEAVE'
     statement.

   * Triggers are not allowed on tables in the `mysql' database.

Stored routines and triggers in MySQL Cluster

Stored functions, stored procedures, and triggers are all supported by
tables using the `NDB' storage engine; however, it is important to keep
in mind that they do _not_ propagate automatically between MySQL
Servers acting as Cluster SQL nodes. This is because of the following:

   * Stored routine definitions are kept in tables in the `mysql'
     system database using the `MyISAM' storage engine, and so do not
     participate in clustering.

   * The `.TRN' and `.TRG' files containing trigger definitions are not
     read by the `NDB' storage engine, and are not copied between
     Cluster nodes.

Any stored routine or trigger that interacts with MySQL Cluster tables
must be re-created by running the appropriate `CREATE PROCEDURE',
`CREATE FUNCTION', or `CREATE TRIGGER' statements on each MySQL Server
that participates in the cluster where you wish to use the stored
routine or trigger. Similarly, any changes to existing stored routines
or triggers must be carried out explicitly on all Cluster SQL nodes,
using the appropriate `ALTER' or `DROP' statements on each MySQL Server
accessing the cluster.

*Warning*:

Do _not_ attempt to work around the issue described in the first item
mentioned previously by converting any `mysql' database tables to use
the `NDB' storage engine.  _Altering the system tables in the `mysql'
database is very likely to produce undesirable results, and is not
supported by MySQL AB_.


File: manual.info,  Node: cursor-restrictions,  Next: subquery-restrictions,  Prev: routine-restrictions,  Up: restrictions

D.2 Restrictions on Server-Side Cursors
=======================================

Server-side cursors are implemented in the C API via the *Note
`mysql_stmt_attr_set()': mysql-stmt-attr-set. function.  The same
implementation is used for cursors in stored routines. A server-side
cursor allows a result set to be generated on the server side, but not
transferred to the client except for those rows that the client
requests. For example, if a client executes a query but is only
interested in the first row, the remaining rows are not transferred.

In MySQL, a server-side cursor is materialized into a temporary table.
Initially, this is a `MEMORY' table, but is converted to a `MyISAM'
table if its size reaches the value of the `max_heap_table_size' system
variable. One limitation of the implementation is that for a large
result set, retrieving its rows through a cursor might be slow.

Cursors are read only; you cannot use a cursor to update rows.

`UPDATE WHERE CURRENT OF' and `DELETE WHERE CURRENT OF' are not
implemented, because updatable cursors are not supported.

Cursors are non-holdable (not held open after a commit).

Cursors are asensitive.

Cursors are non-scrollable.

Cursors are not named. The statement handler acts as the cursor ID.

You can have open only a single cursor per prepared statement. If you
need several cursors, you must prepare several statements.

You cannot use a cursor for a statement that generates a result set if
the statement is not supported in prepared mode. This includes
statements such as `CHECK TABLE', `HANDLER READ', and `SHOW BINLOG
EVENTS'.


File: manual.info,  Node: subquery-restrictions,  Next: view-restrictions,  Prev: cursor-restrictions,  Up: restrictions

D.3 Restrictions on Subqueries
==============================

   * In MySQL 5.1 before 5.1.16, if you compare a `NULL' value to a
     subquery using `ALL', `ANY', or `SOME', and the subquery returns
     an empty result, the comparison might evaluate to the non-standard
     result of `NULL' rather than to `TRUE' or `FALSE'.

   * A subquery's outer statement can be any one of: `SELECT', `INSERT',
     `UPDATE', `DELETE', `SET', or `DO'.

   * Subquery optimization for `IN' is not as effective as for the `='
     operator or for the `IN(VALUE_LIST)' operator.

     A typical case for poor `IN' subquery performance is when the
     subquery returns a small number of rows but the outer query
     returns a large number of rows to be compared to the subquery
     result.

     The problem is that, for a statement that uses an `IN' subquery,
     the optimizer rewrites it as a correlated subquery. Consider the
     following statement that uses an uncorrelated subquery:

          SELECT ... FROM t1 WHERE t1.a IN (SELECT b FROM t2);

     The optimizer rewrites the statement to a correlated subquery:

          SELECT ... FROM t1 WHERE EXISTS (SELECT 1 FROM t2 WHERE t2.b = t1.a);

     If the inner and outer queries return M and N rows, respectively,
     the execution time becomes on the order of `O(MxN)', rather than
     `O(M+N)' as it would be for an uncorrelated subquery.

     An implication is that an `IN' subquery can be much slower than a
     query written using an `IN(VALUE_LIST)' operator that lists the
     same values that the subquery would return.

   * In general, you cannot modify a table and select from the same
     table in a subquery. For example, this limitation applies to
     statements of the following forms:

          DELETE FROM t WHERE ... (SELECT ... FROM t ...);
          UPDATE t ... WHERE col = (SELECT ... FROM t ...);
          {INSERT|REPLACE} INTO t (SELECT ... FROM t ...);

     Exception: The preceding prohibition does not apply if you are
     using a subquery for the modified table in the `FROM' clause.
     Example:

          UPDATE t ... WHERE col = (SELECT * FROM (SELECT ... FROM t...) AS _t ...);

     Here the prohibition does not apply because the result from a
     subquery in the `FROM' clause is stored as a temporary table, so
     the relevant rows in `t' have already been selected by the time
     the update to `t' takes place.

   * Row comparison operations are only partially supported:

        * For `EXPR IN (SUBQUERY)', EXPR can be an N-tuple (specified
          via row constructor syntax) and the subquery can return rows
          of N-tuples.

        * For `EXPR OP {ALL|ANY|SOME} (SUBQUERY)', EXPR must be a
          scalar value and the subquery must be a column subquery; it
          cannot return multiple-column rows.

     In other words, for a subquery that returns rows of N-tuples, this
     is supported:

          (VAL_1, ..., VAL_N) IN (SUBQUERY)

     But this is not supported:

          (VAL_1, ..., VAL_N) OP {ALL|ANY|SOME} (SUBQUERY)

     The reason for supporting row comparisons for `IN' but not for the
     others is that `IN' is implemented by rewriting it as a sequence of
     `=' comparisons and `AND' operations. This approach cannot be used
     for `ALL', `ANY', or `SOME'.

   * Row constructors are not well optimized. The following two
     expressions are equivalent, but only the second can be optimized:

          (col1, col2, ...) = (val1, val2, ...)
          col1 = val1 AND col2 = val2 AND ...

   * Subqueries in the `FROM' clause cannot be correlated subqueries.
     They are materialized (executed to produce a result set) before
     evaluating the outer query, so they cannot be evaluated per row of
     the outer query.

   * The optimizer is more mature for joins than for subqueries, so in
     many cases a statement that uses a subquery can be executed more
     efficiently if you rewrite it as a join.

     An exception occurs for the case where an `IN' subquery can be
     rewritten as a `SELECT DISTINCT' join. Example:

          SELECT col FROM t1 WHERE id_col IN (SELECT id_col2 FROM t2 WHERE CONDITION);

     That statement can be rewritten as follows:

          SELECT DISTINCT col FROM t1, t2 WHERE t1.id_col = t2.id_col AND CONDITION;

     But in this case, the join requires an extra `DISTINCT' operation
     and is not more efficient than the subquery.

   * Possible future optimization: MySQL does not rewrite the join
     order for subquery evaluation. In some cases, a subquery could be
     executed more efficiently if MySQL rewrote it as a join.  This
     would give the optimizer a chance to choose between more execution
     plans. For example, it could decide whether to read one table or
     the other first.

     Example:

          SELECT a FROM outer_table AS ot
          WHERE a IN (SELECT a FROM inner_table AS it WHERE ot.b = it.b);

     For that query, MySQL always scans `outer_table' first and then
     executes the subquery on `inner_table' for each row. If
     `outer_table' has a lot of rows and `inner_table' has few rows,
     the query probably will not be as fast as it could be.

     The preceding query could be rewritten like this:

          SELECT a FROM outer_table AS ot, inner_table AS it
          WHERE ot.a = it.a AND ot.b = it.b;

     In this case, we can scan the small table (`inner_table') and look
     up rows in `outer_table', which will be fast if there is an index
     on `(ot.a,ot.b)'.

   * Possible future optimization: A correlated subquery is evaluated
     for each row of the outer query. A better approach is that if the
     outer row values do not change from the previous row, do not
     evaluate the subquery again. Instead, use its previous result.

   * Possible future optimization: A subquery in the `FROM' clause is
     evaluated by materializing the result into a temporary table, and
     this table does not use indexes. This does not allow the use of
     indexes in comparison with other tables in the query, although
     that might be useful.

   * Possible future optimization: If a subquery in the `FROM' clause
     resembles a view to which the merge algorithm can be applied,
     rewrite the query and apply the merge algorithm so that indexes
     can be used. The following statement contains such a subquery:

          SELECT * FROM (SELECT * FROM t1 WHERE t1.t1_col)
                   AS _t1, t2 WHERE t2.t2_col;

     The statement can be rewritten as a join like this:

          SELECT * FROM t1, t2 WHERE t1.t1_col AND t2.t2_col;

     This type of rewriting would provide two benefits:

        * It avoids the use of a temporary table for which no indexes
          can be used. In the rewritten query, the optimizer can use
          indexes on `t1'.

        * It gives the optimizer more freedom to choose between
          different execution plans. For example, rewriting the query
          as a join allows the optimizer to use `t1' or `t2' first.

   * Possible future optimization: For `IN', `= ANY', `<> ANY', `=
     ALL', and `<> ALL' with uncorrelated subqueries, use an in-memory
     hash for a result or a temporary table with an index for larger
     results.  Example:

          SELECT a FROM big_table AS bt
          WHERE non_key_field IN (SELECT non_key_field FROM TABLE WHERE CONDITION)

     In this case, we could create a temporary table:

          CREATE TABLE t (key (non_key_field))
          (SELECT non_key_field FROM TABLE WHERE CONDITION)

     Then, for each row in `big_table', do a key lookup in `t' based on
     `bt.non_key_field'.


File: manual.info,  Node: view-restrictions,  Next: xa-restrictions,  Prev: subquery-restrictions,  Up: restrictions

D.4 Restrictions on Views
=========================

View processing is not optimized:

   * It is not possible to create an index on a view.

   * Indexes can be used for views processed using the merge algorithm.
     However, a view that is processed with the temptable algorithm is
     unable to take advantage of indexes on its underlying tables
     (although indexes can be used during generation of the temporary
     tables).

Subqueries cannot be used in the `FROM' clause of a view. This
limitation will be lifted in the future.

There is a general principle that you cannot modify a table and select
from the same table in a subquery. See *Note subquery-restrictions::.

The same principle also applies if you select from a view that selects
from the table, if the view selects from the table in a subquery and
the view is evaluated using the merge algorithm.  Example:

     CREATE VIEW v1 AS
     SELECT * FROM t2 WHERE EXISTS (SELECT 1 FROM t1 WHERE t1.a = t2.a);

     UPDATE t1, v2 SET t1.a = 1 WHERE t1.b = v2.b;

If the view is evaluated using a temporary table, you _can_ select from
the table in the view subquery and still modify that table in the outer
query. In this case the view will be stored in a temporary table and
thus you are not really selecting from the table in a subquery and
modifying it `at the same time.' (This is another reason you might wish
to force MySQL to use the temptable algorithm by specifying `ALGORITHM
= TEMPTABLE' in the view definition.)

You can use `DROP TABLE' or `ALTER TABLE' to drop or alter a table that
is used in a view definition (which invalidates the view) and no
warning results from the drop or alter operation. An error occurs later
when the view is used.

A view definition is `frozen' by certain statements:

   * If a statement prepared by `PREPARE' refers to a view, the view
     definition seen each time the statement is executed later will be
     the definition of the view at the time it was prepared. This is
     true even if the view definition is changed after the statement is
     prepared and before it is executed. Example:

          CREATE VIEW v AS SELECT RAND();
          PREPARE s FROM 'SELECT * FROM v';
          ALTER VIEW v AS SELECT NOW();
          EXECUTE s;

     The result returned by the `EXECUTE' statement is a random number,
     not the current date and time.

   * If a statement in a stored routine refers to a view, the view
     definition seen by the statement are its definition the first time
     that statement is executed. For example, this means that if the
     statement is executed in a loop, further iterations of the
     statement see the same view definition, even if the definition is
     changed later in the loop. Example:

          CREATE VIEW v AS SELECT 1;
          delimiter //
          CREATE PROCEDURE p ()
          BEGIN
            DECLARE i INT DEFAULT 0;
            WHILE i < 5 DO
              SELECT * FROM v;
              SET i = i + 1;
              ALTER VIEW v AS SELECT 2;
            END WHILE;
          END;
          //
          delimiter ;
          CALL p();

     When the procedure `p()' is called, the `SELECT' returns 1 each
     time through the loop, even though the view definition is changed
     within the loop.

     As of MySQL 5.1.21, `ALTER VIEW' is prohibited within stored
     routines, so this restriction does not apply.

With regard to view updatability, the overall goal for views is that if
any view is theoretically updatable, it should be updatable in
practice. This includes views that have `UNION' in their definition.
Currently, not all views that are theoretically updatable can be
updated. The initial view implementation was deliberately written this
way to get usable, updatable views into MySQL as quickly as possible.
Many theoretically updatable views can be updated now, but limitations
still exist:

   * Updatable views with subqueries anywhere other than in the `WHERE'
     clause. Some views that have subqueries in the `SELECT' list may be
     updatable.

   * You cannot use `UPDATE' to update more than one underlying table
     of a view that is defined as a join.

   * You cannot use `DELETE' to update a view that is defined as a join.

There exists a shortcoming with the current implementation of views. If
a user is granted the basic privileges necessary to create a view (the
`CREATE VIEW' and `SELECT' privileges), that user will be unable to
call `SHOW CREATE VIEW' on that object unless the user is also granted
the `SHOW VIEW' privilege.

That shortcoming can lead to problems backing up a database with
`mysqldump', which may fail due to insufficient privileges. This
problem is described in Bug#22062 (http://bugs.mysql.com/22062).

The workaround to the problem is for the administrator to manually
grant the `SHOW VIEW' privilege to users who are granted `CREATE VIEW',
since MySQL doesn't grant it implicitly when views are created.

Views do not have indexes, so index hints do not apply. Use of index
hints when selecting from a view is disallowed.


File: manual.info,  Node: xa-restrictions,  Next: charset-restrictions,  Prev: view-restrictions,  Up: restrictions

D.5 Restrictions on XA Transactions
===================================

XA transaction support is limited to the `InnoDB' storage engine.

The MySQL XA implementation is for `external XA,' where a MySQL server
acts as a Resource Manager and client programs act as Transaction
Managers. `Internal XA' is not implemented. This would allow individual
storage engines within a MySQL server to act as RMs, and the server
itself to act as a TM. Internal XA is required for handling XA
transactions that involve more than one storage engine. The
implementation of internal XA is incomplete because it requires that a
storage engine support two-phase commit at the table handler level, and
currently this is true only for `InnoDB'.

For `XA START', the `JOIN' and `RESUME' clauses are not supported.

For `XA END', the `SUSPEND [FOR MIGRATE]' clause is not supported.

The requirement that the BQUAL part of the XID value be different for
each XA transaction within a global transaction is a limitation of the
current MySQL XA implementation. It is not part of the XA specification.

If an XA transaction has reached the `PREPARED' state and the MySQL
server is killed (for example, with `kill -9' on Unix) or shuts down
abnormally, the transaction can be continued after the server restarts.
However, if the client reconnects and commits the transaction, the
transaction will be absent from the binary log even though it has been
committed. This means the data and the binary log have gone out of
synchrony. An implication is that XA cannot be used safely together
with replication.

It is possible that the server will roll back a pending XA transaction,
even one that has reached the `PREPARED' state. This happens if a client
connection terminates and the server continues to run, or if clients
are connected and the server shuts down gracefully. (In the latter
case, the server marks each connection to be terminated, and then rolls
back the `PREPARED' XA transaction associated with it.) It should be
possible to commit or roll back a `PREPARED' XA transaction, but this
cannot be done without changes to the binary logging mechanism.


File: manual.info,  Node: charset-restrictions,  Next: limits,  Prev: xa-restrictions,  Up: restrictions

D.6 Restrictions on Character Sets
==================================

   * Identifiers are stored in `mysql' database tables (`user', `db',
     and so forth) using `utf8', but identifiers can contain only
     characters in the Basic Multilingual Plane (BMP).  Supplementary
     characters are not allowed in identifiers.

   * The `ucs2' character sets has the following restrictions:

        * It cannot be used as a client character set, which means that
          it does not work for `SET NAMES' or `SET CHARACTER SET'. (See
          *Note charset-connection::.)

        * It is currently not possible to use `LOAD DATA INFILE' to
          load data files that use this character set.

        * `FULLTEXT' indexes cannot be created on a column that this
          character set. However, you can perform `IN BOOLEAN MODE'
          searches on the column without an index.

   * The `REGEXP' and `RLIKE' operators work in byte-wise fashion, so
     they are not multi-byte safe and may produce unexpected results
     with multi-byte character sets. In addition, these operators
     compare characters by their byte values and accented characters
     may not compare as equal even if a given collation treats them as
     equal.


File: manual.info,  Node: limits,  Prev: charset-restrictions,  Up: restrictions

D.7 Limits in MySQL
===================

* Menu:

* joins-limits::                 Limits of Joins
* column-count-limit::           The Maximum Number of Columns Per Table
* limits-windows::               Windows Platform Limitations

This section lists current limits in MySQL 5.1.


File: manual.info,  Node: joins-limits,  Next: column-count-limit,  Prev: limits,  Up: limits

D.7.1 Limits of Joins
---------------------

The maximum number of tables that can be referenced in a single join is
61. This also applies to the number of tables that can be referenced in
the definition of a view.


File: manual.info,  Node: column-count-limit,  Next: limits-windows,  Prev: joins-limits,  Up: limits

D.7.2 The Maximum Number of Columns Per Table
---------------------------------------------

There is a hard limit of 4096 columns per table, but the effective
maximum may be less for a given table. The exact limit depends on
several interacting factors, listed in the following discussion.

   * Every table has a maximum row size of 65,535 bytes. This maximum
     applies to all storage engines, but a given engine might have
     additional constraints that result in a lower effective maximum
     row size.

     The maximum row size constrains the number of columns because the
     total width of all columns cannot exceed this size. For example,
     `utf8' characters require up to three bytes per character, so for a
     `CHAR(255) CHARACTER SET utf8' column, the server must allocate
     255 x 3 = 765 bytes per value.  Consequently, a table cannot
     contain more than 65,535 / 765 = 85 such columns.

     Storage for variable-length columns includes length bytes, which
     are assessed against the row size. For example, a `VARCHAR(255)
     CHARACTER SET utf8' column takes two bytes to store the length of
     the value, so each value can take up to 767 bytes.

     `BLOB' and `TEXT' columns count from one to four plus eight bytes
     each toward the row-size limit because their contents are stored
     separately.

     Declaring columns `NULL' can reduce the maximum number of columns
     allowed. `NULL' columns require additional space in the row to
     record whether or not their values are `NULL'.

     For `MyISAM' tables, each `NULL' column takes one bit extra,
     rounded up to the nearest byte. The maximum row length in bytes can
     be calculated as follows:

          row length = 1
                       + (SUM OF COLUMN LENGTHS)
                       + (NUMBER OF NULL COLUMNS + DELETE_FLAG + 7)/8
                       + (NUMBER OF VARIABLE-LENGTH COLUMNS)

     DELETE_FLAG is 1 for tables with static row format. Static tables
     use a bit in the row record for a flag that indicates whether the
     row has been deleted.  DELETE_FLAG is 0 for dynamic tables because
     the flag is stored in the dynamic row header.

     These calculations do not apply for `InnoDB' tables, for which
     storage size is no different for `NULL' columns than for `NOT
     NULL' columns.

     The following statement to create table `t1' succeeds because the
     columns require 32,765 + 2 bytes and 32,766 + 2 bytes, which falls
     within the maximum row size of 65,535 bytes:

          mysql> CREATE TABLE t1
              -> (c1 VARCHAR(32765) NOT NULL, c2 VARCHAR(32766) NOT NULL);
          Query OK, 0 rows affected (0.01 sec)

     The following statement to create table `t2' fails because the
     columns are `NULL' and require additional space that causes the
     row size to exceed 65,535 bytes:

          mysql> CREATE TABLE t2
              -> (c1 VARCHAR(32765) NULL, c2 VARCHAR(32766) NULL);
          ERROR 1118 (42000): Row size too large. The maximum row size for the
          used table type, not counting BLOBs, is 65535. You have to change some
          columns to TEXT or BLOBs

   * Each table has an `.frm' file that contains the table definition.
     The `.frm' file size limit is fixed at 64KB. If a table definition
     reaches this size, no more columns can be added. The expression
     that checks information to be stored in the `.frm' file against
     the limit looks like this:

          if (info_length+(ulong) create_fields.elements*FCOMP+288+
              n_length+int_length+com_length > 65535L || int_count > 255)

     The relevant factors in this expression are:

        * `info_length' is space needed for `screens.' This is related
          to MySQL's Unireg heritage.

        * `create_fields.elements' is the number of columns.

        * `FCOMP' is 17.

        * `n_length' is the total length of all column names, including
          one byte per name as a separator.

        * `int_length' is related to the list of values for SET and
          ENUM columns.

        * `com_length' is the total length of column and table comments.

     Thus, using long column names can reduce the maximum number of
     columns, as can the inclusion of `ENUM' or `SET' columns, or use
     of column or table comments.

   * Individual storage engines might impose additional restrictions
     that limit table column count. Examples:

        * `InnoDB' allows no more than 1000 columns.

        * `InnoDB' restricts row size to something less than half a
          database page (approximately 8000 bytes), not including
          `VARBINARY', `VARCHAR', `BLOB', or `TEXT' columns.

        * Different `InnoDB' storage formats (`COMPRESSED',
          `REDUNDANT') use different amounts of page header and trailer
          data, which affects the amount of storage available for rows.


File: manual.info,  Node: limits-windows,  Prev: column-count-limit,  Up: limits

D.7.3 Windows Platform Limitations
----------------------------------

The following limitations apply only to the Windows platform:

   * The number of open file descriptors on Windows is limited to a
     maximum of 2048, which may limit the ability to open a large
     number of tables simultaneously. This limit is due to the
     compatibility functions used to open files on Windows that use the
     POSIX compatibility layer.

     This limitation will also cause problems if you try to set
     `max_open_files' to a value greater than the 2048 file limit.

   * On Windows 32-bit platforms it is not possible to use more than
     2GB of RAM within a single process, including MySQL.  This is
     because the physical address limit on Windows 32-bit is 4GB and
     the default setting within Windows is to split the virtual address
     space between kernel (2GB) and user/applications (2GB).

     To use more memory than this you will need to use a 64-bit version
     of Windows.

   * When using `MyISAM' tables, you cannot use aliases within Windows
     link to the data files on another volume and then link back to the
     main MySQL `datadir' location.

     This facility is often used to move the data and index files to a
     RAID or other fast solution, while retaining the main `.FRM' files
     in the default data directory configured with the `datadir' option.

   * The timers within MySQL used on Windows are of a lower precision
     than the timers used on Linux. For most situations you may not
     notice a difference, but the delay implied by a call to `SLEEP()'
     on Windows and Linux may differ slightly due to the differences in
     precision.

   * There is no 64-bit OLEDB Provider for ODBC (MSDASQL) in any 64-bit
     Windows operating system up to and including Windows Vista. In
     practical terms this means that you can't use the MySQL ODBC
     driver from ADO and other users of OLEDB.


File: manual.info,  Node: credits,  Prev: restrictions,  Up: Top

Appendix E Credits
******************

* Menu:

* developers::                   Developers at MySQL AB
* contributors::                 Contributors to MySQL
* documenters-translators::      Documenters and translators
* used-libraries::               Libraries used by and included with MySQL
* packages::                     Packages that support MySQL
* tools-used-to-create-mysql::   Tools that were used to create MySQL
* supporters::                   Supporters of MySQL

This appendix lists the developers, contributors, and supporters that
have helped to make MySQL what it is today.


File: manual.info,  Node: developers,  Next: contributors,  Prev: credits,  Up: credits

E.1 Developers at MySQL AB
==========================

These are the developers that are or have been employed by MySQL AB to
work on the `MySQL' database software, roughly in the order they
started to work with us. Following each developer is a small list of
the tasks that the developer is responsible for, or the accomplishments
they have made. All developers are involved in support.

   * Michael (Monty) Widenius

        * Lead developer and main author of the MySQL server (`mysqld').

        * New functions for the string library.

        * Most of the `mysys' library.

        * The `ISAM' and `MyISAM' libraries (B-tree index file handlers
          with index compression and different record formats).

        * The `HEAP' library. A memory table system with our superior
          full dynamic hashing. In use since 1981 and published around
          1984.

        * The `replace' program (take a look at it, it's *COOL*!).

        * Connector/ODBC (MyODBC), the ODBC driver for Windows.

        * Fixing bugs in MIT-pthreads to get it to work for MySQL
          Server. And also Unireg, a curses-based application tool with
          many utilities.

        * Porting of `mSQL' tools like `msqlperl', `DBD'/`DBI', and
          `DB2mysql'.

        * Most of `crash-me' and the foundation for the MySQL
          benchmarks.

   * David Axmark

        * Initial main writer of the *Reference Manual*, including
          enhancements to `texi2html'.

        * Automatic Web site updating from the manual.

        * Initial Autoconf, Automake, and Libtool support.

        * Licensing.

        * Parts of all the text files. (Nowadays only the `README' is
          left. The rest ended up in the manual.)

        * Lots of testing of new features.

        * Our in-house Free Software legal expert.

        * Mailing list maintainer (who never has the time to do it
          right...).

        * Our original portability code (now more than 10 years old).
          Nowadays only some parts of `mysys' are left.

        * Someone for Monty to call in the middle of the night when he
          just got that new feature to work.

        * Chief "Open Sourcerer" (MySQL community relations).

   * Jani Tolonen

        * `mysqlimport'

        * A lot of extensions to the command-line clients.

        * `PROCEDURE ANALYSE()'

   * Sinisa Milivojevic (now in support)

        * Compression (with `zlib') in the client/server protocol.

        * Perfect hashing for the lexical analyzer phase.

        * Multi-row `INSERT'

        * `mysqldump' -e option

        * `LOAD DATA LOCAL INFILE'

        * `SQL_CALC_FOUND_ROWS' `SELECT' option

        * `--max-user-connections=...' option

        * `net_read' and `net_write_timeout'

        * `GRANT'/`REVOKE' and `SHOW GRANTS FOR'

        * New client/server protocol for 4.0

        * `UNION' in 4.0

        * Multiple-table `DELETE'/`UPDATE'

        * Subqueries in the `FROM' clause (4.1).

        * User resources management

        * Initial developer of the `MySQL++' C++ API and the `MySQLGUI'
          client.

   * Tonu Samuel (past developer)

        * VIO interface (the foundation for the encrypted client/server
          protocol).

        * MySQL Filesystem (a way to use MySQL databases as files and
          directories).

        * The `CASE' expression.

        * The `MD5()' and `COALESCE()' functions.

        * `RAID' support for `MyISAM' tables.

   * Sasha Pachev (past developer)

        * Initial implementation of replication (up to version 4.0).

        * `SHOW CREATE TABLE'.

        * `mysql-bench'

   * Matt Wagner

        * MySQL test suite.

        * Webmaster (until 2002).

   * Miguel Solorzano (now in support)

        * Win32 development and release builds.

        * Windows NT server code.

        * WinMySQLAdmin

   * Timothy Smith (now in development)

        * Dynamic character sets support.

        * configure, RPMs and other parts of the build system.

        * Initial developer of `libmysqld', the embedded server.

   * Sergei Golubchik

        * Full-text search.

        * Added keys to the `MERGE' library.

        * Precision math.

   * Jeremy Cole (past developer)

        * Proofreading and editing this fine manual.

        * `ALTER TABLE ... ORDER BY ...'.

        * `UPDATE ... ORDER BY ...'.

        * `DELETE ... ORDER BY ...'.

   * Indrek Siitan

        * Designing/programming of our Web interface.

        * Author of our newsletter management system.

   * Jorge del Conde (past developer)

        * `MySQLCC' (`MySQL Control Center')

        * Win32 development

        * Initial implementation of the Web site portals.

   * Venu Anuganti (past developer)

        * MyODBC 3.51

        * New client/server protocol for 4.1 (for prepared statements).

   * Arjen Lentz (also handled community, 2004-2006; now works in
     Support)

        * Maintainer of the MySQL Reference Manual (2001-2004).

        * Preparing the O'Reilly printed edition of the manual (2002).

   * Alexander (Bar) Barkov, Alexey (Holyfoot) Botchkov, and Ramil
     Kalimullin

        * Spatial data (GIS) and R-Trees implementation for 4.1

        * Unicode and character sets for 4.1; documentation for same

   * Oleksandr (Sanja) Byelkin

        * Query cache in 4.0

        * Implementation of subqueries (4.1).

        * Implementation of views (5.0).

   * Aleksey (Walrus) Kishkin and Alexey (Ranger) Stroganov

        * Benchmarks design and analysis.

        * Maintenance of the MySQL test suite.

   * Zak Greant (past employee)

        * Open Source advocate, MySQL community relations.

   * Carsten Pedersen

        * The MySQL Certification program.

   * Lenz Grimmer

        * Production (build and release) engineering.

   * Peter Zaitsev

        * `SHA1()', `AES_ENCRYPT()' and `AES_DECRYPT()' functions.

        * Debugging, cleaning up various features.

   * Alexander (Salle) Keremidarski

        * Support.

        * Debugging.

   * Per-Erik Martin

        * Lead developer for stored procedures (5.0).

   * Jim Winstead

        * Former lead Web developer.

        * Improving server, fixing bugs.

   * Mark Matthews

        * Connector/J driver (Java).

   * Peter Gulutzan

        * SQL standards compliance.

        * Documentation of existing MySQL code/algorithms.

        * Character set documentation.

   * Guilhem Bichot

        * Replication, from `MySQL' version 4.0.

        * Fixed handling of exponents for `DECIMAL'.

        * Author of `mysql_tableinfo'.

        * Backup (in 5.1).

   * Antony T. Curtis

        * Porting of the MySQL Database software to OS/2.

   * Mikael Ronstrom

        * Much of the initial work on NDB Cluster until 2000.  Roughly
          half the code base at that time. Transaction protocol, node
          recovery, system restart and restart code and parts of the
          API functionality.

        * Lead Architect, developer, debugger of NDB Cluster 1994-2004

        * Lots of optimizations

   * Jonas Oreland

        * On-line Backup

        * The automatic test environment of MySQL Cluster

        * Portability Library for NDB Cluster

        * Lots of other things

   * Pekka Nouisiainen

        * Ordered index implementation of MySQL Cluster

        * BLOB support in MySQL Cluster

        * Charset support in MySQL Cluster

   * Martin Skold

        * Unique index implementation of MySQL Cluster

        * Integration of NDB Cluster into MySQL

   * Magnus Svensson

        * The test framework for MySQL Cluster

        * Integration of NDB Cluster into MySQL

   * Tomas Ulin

        * Lots of work on configuration changes for simple installation
          and use of MySQL Cluster

   * Konstantin Osipov

        * Prepared statements.

        * Cursors.

   * Dmitri Lenev

        * Time zone support.

        * Triggers (in 5.0).


File: manual.info,  Node: contributors,  Next: documenters-translators,  Prev: developers,  Up: credits

E.2 Contributors to MySQL
=========================

Although MySQL AB owns all copyrights in the `MySQL server' and the
`MySQL manual', we wish to recognize those who have made contributions
of one kind or another to the `MySQL distribution'. Contributors are
listed here, in somewhat random order:

   * Gianmassimo Vigazzola <qwerg@mbox.vol.it> or <qwerg@tin.it>

     The initial port to Win32/NT.

   * Per Eric Olsson

     For more or less constructive criticism and real testing of the
     dynamic record format.

   * Irena Pancirov <irena@mail.yacc.it>

     Win32 port with Borland compiler.  `mysqlshutdown.exe' and
     `mysqlwatch.exe'

   * David J. Hughes

     For the effort to make a shareware SQL database. At TcX, the
     predecessor of MySQL AB, we started with `mSQL', but found that it
     couldn't satisfy our purposes so instead we wrote an SQL interface
     to our application builder Unireg. `mysqladmin' and `mysql' client
     are programs that were largely influenced by their `mSQL'
     counterparts. We have put a lot of effort into making the MySQL
     syntax a superset of `mSQL'. Many of the API's ideas are borrowed
     from `mSQL' to make it easy to port free `mSQL' programs to the
     MySQL API.  The MySQL software doesn't contain any code from
     `mSQL'. Two files in the distribution (`client/insert_test.c' and
     `client/select_test.c') are based on the corresponding
     (non-copyrighted) files in the `mSQL' distribution, but are
     modified as examples showing the changes necessary to convert code
     from `mSQL' to MySQL Server.  (`mSQL' is copyrighted David J.
     Hughes.)

   * Patrick Lynch

     For helping us acquire `http://www.mysql.com/'.

   * Fred Lindberg

     For setting up qmail to handle the MySQL mailing list and for the
     incredible help we got in managing the MySQL mailing lists.

   * Igor Romanenko <igor@frog.kiev.ua>

     `mysqldump' (previously `msqldump', but ported and enhanced by
     Monty).

   * Yuri Dario

     For keeping up and extending the MySQL OS/2 port.

   * Tim Bunce

     Author of `mysqlhotcopy'.

   * Zarko Mocnik <zarko.mocnik@dem.si>

     Sorting for Slovenian language.

   * "TAMITO" <tommy@valley.ne.jp>

     The `_MB' character set macros and the ujis and sjis character
     sets.

   * Joshua Chamas <joshua@chamas.com>

     Base for concurrent insert, extended date syntax, debugging on NT,
     and answering on the MySQL mailing list.

   * Yves Carlier <Yves.Carlier@rug.ac.be>

     `mysqlaccess', a program to show the access rights for a user.

   * Rhys Jones <rhys@wales.com> (And GWE Technologies Limited)

     For one of the early JDBC drivers.

   * Dr Xiaokun Kelvin ZHU <X.Zhu@brad.ac.uk>

     Further development of one of the early JDBC drivers and other
     MySQL-related Java tools.

   * James Cooper <pixel@organic.com>

     For setting up a searchable mailing list archive at his site.

   * Rick Mehalick <Rick_Mehalick@i-o.com>

     For `xmysql', a graphical X client for MySQL Server.

   * Doug Sisk <sisk@wix.com>

     For providing RPM packages of MySQL for Red Hat Linux.

   * Diemand Alexander V. <axeld@vial.ethz.ch>

     For providing RPM packages of MySQL for Red Hat Linux-Alpha.

   * Antoni Pamies Olive <toni@readysoft.es>

     For providing RPM versions of a lot of MySQL clients for Intel and
     SPARC.

   * Jay Bloodworth <jay@pathways.sde.state.sc.us>

     For providing RPM versions for MySQL 3.21.

   * David Sacerdote <davids@secnet.com>

     Ideas for secure checking of DNS hostnames.

   * Wei-Jou Chen <jou@nematic.ieo.nctu.edu.tw>

     Some support for Chinese(BIG5) characters.

   * Wei He <hewei@mail.ied.ac.cn>

     A lot of functionality for the Chinese(GBK) character set.

   * Jan Pazdziora <adelton@fi.muni.cz>

     Czech sorting order.

   * Zeev Suraski <bourbon@netvision.net.il>

     `FROM_UNIXTIME()' time formatting, `ENCRYPT()' functions, and
     `bison' advisor. Active mailing list member.

   * Luuk de Boer <luuk@wxs.nl>

     Ported (and extended) the benchmark suite to `DBI'/`DBD'. Have
     been of great help with `crash-me' and running benchmarks. Some
     new date functions. The `mysql_setpermission' script.

   * Alexis Mikhailov <root@medinf.chuvashia.su>

     User-defined functions (UDFs); `CREATE FUNCTION' and `DROP
     FUNCTION'.

   * Andreas F. Bobak <bobak@relog.ch>

     The `AGGREGATE' extension to user-defined functions.

   * Ross Wakelin <R.Wakelin@march.co.uk>

     Help to set up InstallShield for MySQL-Win32.

   * Jethro Wright III <jetman@li.net>

     The `libmysql.dll' library.

   * James Pereria <jpereira@iafrica.com>

     Mysqlmanager, a Win32 GUI tool for administering MySQL Servers.

   * Curt Sampson <cjs@portal.ca>

     Porting of MIT-pthreads to NetBSD/Alpha and NetBSD 1.3/i386.

   * Martin Ramsch <m.ramsch@computer.org>

     Examples in the MySQL Tutorial.

   * Steve Harvey

     For making `mysqlaccess' more secure.

   * Konark IA-64 Centre of Persistent Systems Private Limited

     `http://www.pspl.co.in/konark/'. Help with the Win64 port of the
     MySQL server.

   * Albert Chin-A-Young.

     Configure updates for Tru64, large file support and better TCP
     wrappers support.

   * John Birrell

     Emulation of `pthread_mutex()' for OS/2.

   * Benjamin Pflugmann

     Extended `MERGE' tables to handle `INSERTS'. Active member on the
     MySQL mailing lists.

   * Jocelyn Fournier

     Excellent spotting and reporting innumerable bugs (especially in
     the MySQL 4.1 subquery code).

   * Marc Liyanage

     Maintaining the Mac OS X packages and providing invaluable
     feedback on how to create Mac OS X PKGs.

   * Robert Rutherford

     Providing invaluable information and feedback about the QNX port.

   * Previous developers of NDB Cluster

     Lots of people were involved in various ways summer students,
     master thesis students, employees. In total more than 100 people
     so too many to mention here. Notable name is Ataullah Dabaghi who
     up until 1999 contributed around a third of the code base. A
     special thanks also to developers of the AXE system which provided
     much of the architectural foundations for NDB Cluster with blocks,
     signals and crash tracing functionality. Also credit should be
     given to those who believed in the ideas enough to allocate of
     their budgets for its development from 1992 to present time.

Other contributors, bugfinders, and testers: James H. Thompson,
Maurizio Menghini, Wojciech Tryc, Luca Berra, Zarko Mocnik, Wim Bonis,
Elmar Haneke, <jehamby@lightside>, <psmith@BayNetworks.com>,
<duane@connect.com.au>, Ted Deppner <ted@psyber.com>, Mike Simons,
Jaakko Hyvatti.

And lots of bug report/patches from the folks on the mailing list.

A big tribute goes to those that help us answer questions on the MySQL
mailing lists:

   * Daniel Koch <dkoch@amcity.com>

     Irix setup.

   * Luuk de Boer <luuk@wxs.nl>

     Benchmark questions.

   * Tim Sailer <tps@users.buoy.com>

     `DBD::mysql' questions.

   * Boyd Lynn Gerber <gerberb@zenez.com>

     SCO-related questions.

   * Richard Mehalick <RM186061@shellus.com>

     `xmysql'-related questions and basic installation questions.

   * Zeev Suraski <bourbon@netvision.net.il>

     Apache module configuration questions (log & auth), PHP-related
     questions, SQL syntax-related questions and other general
     questions.

   * Francesc Guasch <frankie@citel.upc.es>

     General questions.

   * Jonathan J Smith <jsmith@wtp.net>

     Questions pertaining to OS-specifics with Linux, SQL syntax, and
     other things that might need some work.

   * David Sklar <sklar@student.net>

     Using MySQL from PHP and Perl.

   * Alistair MacDonald <A.MacDonald@uel.ac.uk>

     Is flexible and can handle Linux and perhaps HP-UX. Tries to get
     users to use `mysqlbug'.

   * John Lyon <jlyon@imag.net>

     Questions about installing MySQL on Linux systems, using either
     `.rpm' files or compiling from source.

   * Lorvid Ltd. <lorvid@WOLFENET.com>

     Simple billing/license/support/copyright issues.

   * Patrick Sherrill <patrick@coconet.com>

     ODBC and VisualC++ interface questions.

   * Randy Harmon <rjharmon@uptimecomputers.com>

     `DBD', Linux, some SQL syntax questions.


File: manual.info,  Node: documenters-translators,  Next: used-libraries,  Prev: contributors,  Up: credits

E.3 Documenters and translators
===============================

The following people have helped us with writing the MySQL
documentation and translating the documentation or error messages in
MySQL.

   * Paul DuBois

     Ongoing help with making this manual correct and understandable.
     That includes rewriting Monty's and David's attempts at English
     into English as other people know it.

   * Kim Aldale

     Helped to rewrite Monty's and David's early attempts at English
     into English.

   * Michael J. Miller Jr.  <mke@terrapin.turbolift.com>

     For the first MySQL manual. And a lot of spelling/language fixes
     for the FAQ (that turned into the MySQL manual a long time ago).

   * Yan Cailin

     First translator of the MySQL Reference Manual into simplified
     Chinese in early 2000 on which the Big5 and HK coded
     (`http://mysql.hitstar.com/') versions were based. Personal home
     page at linuxdb.yeah.net (http://linuxdb.yeah.net).

   * Jay Flaherty <fty@mediapulse.com>

     Big parts of the Perl `DBI'/`DBD' section in the manual.

   * Paul Southworth <pauls@etext.org>, Ray Loyzaga <yar@cs.su.oz.au>

     Proof-reading of the Reference Manual.

   * Therrien Gilbert <gilbert@ican.net>, Jean-Marc Pouyot
     <jmp@scalaire.fr>

     French error messages.

   * Petr Snajdr, <snajdr@pvt.net>

     Czech error messages.

   * Jaroslaw Lewandowski <jotel@itnet.com.pl>

     Polish error messages.

   * Miguel Angel Fernandez Roiz

     Spanish error messages.

   * Roy-Magne Mo <rmo@www.hivolda.no>

     Norwegian error messages and testing of MySQL 3.21.xx.

   * Timur I. Bakeyev <root@timur.tatarstan.ru>

     Russian error messages.

   * <brenno@dewinter.com> & Filippo Grassilli <phil@hyppo.com>

     Italian error messages.

   * Dirk Munzinger <dirk@trinity.saar.de>

     German error messages.

   * Billik Stefan <billik@sun.uniag.sk>

     Slovak error messages.

   * Stefan Saroiu <tzoompy@cs.washington.edu>

     Romanian error messages.

   * Peter Feher

     Hungarian error messages.

   * Roberto M. Serqueira

     Portuguese error messages.

   * Carsten H. Pedersen

     Danish error messages.

   * Arjen Lentz

     Dutch error messages, completing earlier partial translation (also
     work on consistency and spelling).


File: manual.info,  Node: used-libraries,  Next: packages,  Prev: documenters-translators,  Up: credits

E.4 Libraries used by and included with MySQL
=============================================

The following is a list of the creators of the libraries we have
included with the MySQL server source to make it easy to compile and
install MySQL. We are very thankfully to all individuals that have
created these and it has made our life much easier.

   * Fred Fish

     For his excellent C debugging and trace library. Monty has made a
     number of smaller improvements to the library (speed and
     additional options).

   * Richard A. O'Keefe

     For his public domain string library.

   * Henry Spencer

     For his regex library, used in `WHERE column REGEXP regexp'.

   * Chris Provenzano

     Portable user level pthreads. From the copyright: This product
     includes software developed by Chris Provenzano, the University of
     California, Berkeley, and contributors. We are currently using
     version 1_60_beta6 patched by Monty (see
     `mit-pthreads/Changes-mysql').

   * Jean-loup Gailly and Mark Adler

     For the zlib library (used on MySQL on Windows).

   * Bjorn Benson

     For his safe_malloc (memory checker) package which is used in when
     you build MySQL using one of the `BUILD/compile-*-debug' scripts,
     or manually set the `-DSAFE_MALLOC'.

   * Free Software Foundation

     The `readline' library (used by the `mysql' command-line client).

   * The NetBSD foundation

     The `libedit' package (optionally used by the `mysql' command-line
     client).

   * www.netlib.org (http://www.netlib.org)

     MySQL incorporates work covered by the following copyright and
     permission notice:

     The author of this software is David M. Gay.

     Copyright (c) 1991, 2000, 2001 by Lucent Technologies.

     Permission to use, copy, modify, and distribute this software for
     any purpose without fee is hereby granted, provided that this
     entire notice is included in all copies of any software which is
     or includes a copy or modification of this software and in all
     copies of the supporting documentation for such software.

     THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
     IMPLIED WARRANTY. IN PARTICULAR, NEITHER THE AUTHOR NOR LUCENT
     MAKES ANY REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE
     MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
     PURPOSE.


File: manual.info,  Node: packages,  Next: tools-used-to-create-mysql,  Prev: used-libraries,  Up: credits

E.5 Packages that support MySQL
===============================

The following is a list of creators/maintainers of some of the most
important API/packages/applications that a lot of people use with MySQL.

We can't list every possible package here because the list would then
be way to hard to maintain. For other packages, please refer to the
software portal at `http://solutions.mysql.com/software/'.

   * Tim Bunce, Alligator Descartes

     For the `DBD' (Perl) interface.

   * Andreas Koenig <a.koenig@mind.de>

     For the Perl interface for MySQL Server.

   * Jochen Wiedmann <wiedmann@neckar-alb.de>

     For maintaining the Perl `DBD::mysql' module.

   * Eugene Chan <eugene@acenet.com.sg>

     For porting PHP for MySQL Server.

   * Georg Richter

     MySQL 4.1 testing and bug hunting. New PHP 5.0 `mysqli' extension
     (API) for use with MySQL 4.1 and up.

   * Giovanni Maruzzelli <maruzz@matrice.it>

     For porting iODBC (Unix ODBC).

   * Xavier Leroy <Xavier.Leroy@inria.fr>

     The author of LinuxThreads (used by the MySQL Server on Linux).


File: manual.info,  Node: tools-used-to-create-mysql,  Next: supporters,  Prev: packages,  Up: credits

E.6 Tools that were used to create MySQL
========================================

The following is a list of some of the tools we have used to create
MySQL. We use this to express our thanks to those that has created them
as without these we could not have made MySQL what it is today.

   * Free Software Foundation

     From whom we got an excellent compiler (`gcc'), an excellent
     debugger (`gdb' and the `libc' library (from which we have borrowed
     `strto.c' to get some code working in Linux).

   * Free Software Foundation & The XEmacs development team

     For a really great editor/environment used by almost everybody at
     MySQL AB.

   * Julian Seward

     Author of `valgrind', an excellent memory checker tool that has
     helped us find a lot of otherwise hard to find bugs in MySQL.

   * Dorothea Lu"tkehaus and Andreas Zeller

     For `DDD' (The Data Display Debugger) which is an excellent
     graphical front end to `gdb').


File: manual.info,  Node: supporters,  Prev: tools-used-to-create-mysql,  Up: credits

E.7 Supporters of MySQL
=======================

Although MySQL AB owns all copyrights in the `MySQL server' and the
`MySQL manual', we wish to recognize the following companies, which
helped us finance the development of the `MySQL server', such as by
paying us for developing a new feature or giving us hardware for
development of the `MySQL server'.

   * VA Linux / Andover.net

     Funded replication.

   * NuSphere

     Editing of the MySQL manual.

   * Stork Design studio

     The MySQL Web site in use between 1998-2000.

   * Intel

     Contributed to development on Windows and Linux platforms.

   * Compaq

     Contributed to Development on Linux/Alpha.

   * SWSoft

     Development on the embedded `mysqld' version.

   * FutureQuest

     `--skip-show-database'

[index]
* Menu:

* ! (logical NOT):                       logical-operators.  (line   27)
* != (not equal):                        comparison-operators.
                                                             (line   82)
* ":                                     identifiers.        (line   20)
* #mysql50 identifier prefix <1>:        identifier-mapping. (line   83)
* #mysql50 identifier prefix:            identifiers.        (line   93)
* %:                                     arithmetic-functions.
                                                             (line  108)
* % (modulo):                            mathematical-functions.
                                                             (line  300)
* % (wildcard character):                string-syntax.      (line   57)
* & (bitwise AND):                       bit-functions.      (line   27)
* && (logical AND):                      logical-operators.  (line   46)
* () (parentheses):                      operator-precedence.
                                                             (line   37)
* (Control-Z) \Z <1>:                    load-data.          (line  417)
* (Control-Z) \Z:                        string-syntax.      (line   55)
* * (multiplication):                    arithmetic-functions.
                                                             (line   70)
* + (addition):                          arithmetic-functions.
                                                             (line   43)
* - (subtraction):                       arithmetic-functions.
                                                             (line   50)
* - (unary minus):                       arithmetic-functions.
                                                             (line   57)
* -? option, MySQL Cluster programs:     mysql-cluster-command-options.
                                                             (line   21)
* -bind-address option (ndb_mgmd):       mysql-cluster-ndb-mgmd-command-options.
                                                             (line    9)
* -c option (MySQL Cluster):             mysql-cluster-command-options.
                                                             (line   26)
* -c option (ndb_mgmd) (OBSOLETE):       mysql-cluster-ndb-mgmd-command-options.
                                                             (line   24)
* -config-file option (ndb_mgmd):        mysql-cluster-ndb-mgmd-command-options.
                                                             (line   24)
* -connect-string option (MySQL Cluster): mysql-cluster-command-options.
                                                             (line   26)
* -debug option (MySQL Cluster):         mysql-cluster-command-options.
                                                             (line   35)
* -e option (MySQL Cluster):             mysql-cluster-command-options.
                                                             (line   41)
* -execute option (MySQL Cluster):       mysql-cluster-command-options.
                                                             (line   41)
* -f option (ndb_mgmd):                  mysql-cluster-ndb-mgmd-command-options.
                                                             (line   24)
* -help option, MySQL Cluster programs:  mysql-cluster-command-options.
                                                             (line   21)
* -initial option (ndbd):                mysql-cluster-ndbd-command-options.
                                                             (line   22)
* -initial-start option (ndbd):          mysql-cluster-ndbd-command-options.
                                                             (line   59)
* -n option (ndbd):                      mysql-cluster-ndbd-command-options.
                                                             (line  110)
* -ndb-log-update-as-write (mysqld option): mysql-cluster-replication-conflict-resolution.
                                                             (line   55)
* -nodaemon option (ndbd):               mysql-cluster-ndbd-command-options.
                                                             (line  104)
* -nostart option (ndbd):                mysql-cluster-ndbd-command-options.
                                                             (line  110)
* -nowait-nodes option (ndbd):           mysql-cluster-ndbd-command-options.
                                                             (line   82)
* -p option:                             password-security.  (line   15)
* -P option (ndb_mgmd):                  mysql-cluster-ndb-mgmd-command-options.
                                                             (line   41)
* -password option:                      password-security.  (line   15)
* -print-full-config option (ndb_mgmd):  mysql-cluster-ndb-mgmd-command-options.
                                                             (line   41)
* -usage option, MySQL Cluster programs: mysql-cluster-command-options.
                                                             (line   21)
* -V option (MySQL Cluster):             mysql-cluster-command-options.
                                                             (line   59)
* -version option (MySQL Cluster):       mysql-cluster-command-options.
                                                             (line   59)
* .my.cnf file <1>:                      multiple-server-clients.
                                                             (line   34)
* .my.cnf file <2>:                      password-security.  (line   49)
* .my.cnf file <3>:                      access-denied.      (line  101)
* .my.cnf file <4>:                      option-files.       (line   11)
* .my.cnf file:                          connecting.         (line  198)
* .mysql_history file:                   mysql-command-options.
                                                             (line  566)
* .pid (process ID) file:                maintenance-schedule.
                                                             (line   16)
* / (division):                          arithmetic-functions.
                                                             (line   85)
* /etc/passwd <1>:                       select.             (line  301)
* /etc/passwd:                           security-against-attack.
                                                             (line  107)
* := (assignment):                       user-variables.     (line    6)
* < (less than):                         comparison-operators.
                                                             (line  100)
* <<:                                    calculating-days.   (line    6)
* << (left shift):                       bit-functions.      (line   49)
* <= (less than or equal):               comparison-operators.
                                                             (line   93)
* <=> (equal to):                        comparison-operators.
                                                             (line   70)
* <> (not equal):                        comparison-operators.
                                                             (line   82)
* <errortext>Table is full</errortext> error, MySQL Cluster: faqs-mysql-cluster.
                                                             (line   58)
* = (assignment):                        user-variables.     (line    6)
* = (equal):                             comparison-operators.
                                                             (line   55)
* > (greater than):                      comparison-operators.
                                                             (line  114)
* >= (greater than or equal):            comparison-operators.
                                                             (line  107)
* >> (right shift):                      bit-functions.      (line   58)
* [api] (MySQL Cluster):                 mysql-cluster-config-params-api.
                                                             (line    6)
* [mgm] (MySQL Cluster):                 mysql-cluster-config-params-mgm.
                                                             (line    6)
* [ndb_mgmd] (MySQL Cluster):            mysql-cluster-config-params-mgm.
                                                             (line    6)
* [ndbd default] (MySQL Cluster):        mysql-cluster-config-params-ndbd.
                                                             (line    6)
* [ndbd] (MySQL Cluster):                mysql-cluster-config-params-ndbd.
                                                             (line    6)
* [SQL] (MySQL Cluster):                 mysql-cluster-config-params-api.
                                                             (line    6)
* \" (double quote):                     string-syntax.      (line   50)
* \' (single quote):                     string-syntax.      (line   49)
* \. (mysql client command) <1>:         batch-commands.     (line    6)
* \. (mysql client command):             batch-mode.         (line   90)
* \0 (ASCII 0) <1>:                      load-data.          (line  412)
* \0 (ASCII 0):                          string-syntax.      (line   48)
* \\ (escape):                           string-syntax.      (line   56)
* \b (backspace) <1>:                    load-data.          (line  413)
* \b (backspace):                        string-syntax.      (line   51)
* \n (linefeed) <1>:                     load-data.          (line  414)
* \n (linefeed):                         string-syntax.      (line   52)
* \n (newline) <1>:                      load-data.          (line  414)
* \n (newline):                          string-syntax.      (line   52)
* \N (NULL):                             load-data.          (line  418)
* \r (carriage return) <1>:              load-data.          (line  415)
* \r (carriage return):                  string-syntax.      (line   53)
* \t (tab) <1>:                          load-data.          (line  416)
* \t (tab):                              string-syntax.      (line   54)
* \Z (Control-Z) ASCII 26 <1>:           load-data.          (line  417)
* \Z (Control-Z) ASCII 26:               string-syntax.      (line   55)
* ^ (bitwise XOR):                       bit-functions.      (line   36)
* _ (wildcard character):                string-syntax.      (line   58)
* _rowid:                                create-table.       (line  379)
* `:                                     identifiers.        (line   20)
* abort-slave-event-count option, mysqld: server-options.    (line   54)
* aborted clients:                       communication-errors.
                                                             (line    6)
* aborted connection:                    communication-errors.
                                                             (line    6)
* ABS():                                 mathematical-functions.
                                                             (line   52)
* access control:                        connection-access.  (line    6)
* access denied errors:                  error-access-denied.
                                                             (line    6)
* access privileges:                     privilege-system.   (line   17)
* account privileges, adding:            adding-users.       (line    6)
* accounts, anonymous user:              default-privileges. (line    6)
* accounts, root:                        default-privileges. (line    6)
* ACID <1>:                              innodb-overview.    (line    6)
* ACID:                                  ansi-diff-transactions.
                                                             (line    6)
* ACLs:                                  privilege-system.   (line   17)
* ACOS():                                mathematical-functions.
                                                             (line   63)
* Active Server Pages (ASP):             myodbc-usagenotes-apptips-microsoft-asp.
                                                             (line    6)
* ActiveState Perl:                      activestate-perl.   (line    6)
* add-drop-database option, mysqldump:   mysqldump.          (line  259)
* add-drop-table option, mysqldump:      mysqldump.          (line  264)
* add-locks option, mysqldump:           mysqldump.          (line  268)
* add-user option, mysqlmanager:         instance-manager-command-options.
                                                             (line   27)
* ADDDATE():                             date-and-time-functions.
                                                             (line  129)
* adding, character sets:                adding-character-set.
                                                             (line   12)
* adding, native functions:              adding-native-function.
                                                             (line    6)
* adding, new account privileges:        adding-users.       (line    6)
* adding, new functions:                 adding-functions.   (line   12)
* adding, new user privileges:           adding-users.       (line    6)
* adding, new users <1>:                 quick-install.      (line  166)
* adding, new users:                     installing-binary.  (line  167)
* adding, procedures:                    adding-procedures.  (line   11)
* adding, user-defined functions:        adding-udf.         (line   15)
* addition (+):                          arithmetic-functions.
                                                             (line   43)
* ADDTIME():                             date-and-time-functions.
                                                             (line  147)
* addtodest option, mysqlhotcopy:        mysqlhotcopy.       (line   72)
* administrative programs:               programs-overview.  (line  160)
* AES_DECRYPT():                         encryption-functions.
                                                             (line   40)
* AES_ENCRYPT():                         encryption-functions.
                                                             (line   46)
* After create, thread state:            general-thread-states.
                                                             (line   11)
* age, calculating:                      date-calculations.  (line    6)
* alias:                                 problems-with-alias.
                                                             (line    6)
* alias names, case sensitivity:         identifier-case-sensitivity.
                                                             (line    6)
* aliases, for expressions:              group-by-hidden-fields.
                                                             (line   51)
* aliases, for tables:                   select.             (line  133)
* aliases, in GROUP BY clauses:          group-by-hidden-fields.
                                                             (line   51)
* aliases, names:                        identifiers.        (line   13)
* aliases, on expressions:               select.             (line   80)
* ALL <1>:                               all-subqueries.     (line    6)
* ALL:                                   select.             (line  403)
* ALL join type, optimizer:              using-explain.      (line  263)
* all-databases option, mysqlcheck:      mysqlcheck.         (line  157)
* all-databases option, mysqldump:       mysqldump.          (line  274)
* all-in-1 option, mysqlcheck:           mysqlcheck.         (line  163)
* all-tablespaces option, mysqldump:     mysqldump.          (line  280)
* allocating local table, thread state:  delayed-insert-thread-states.
                                                             (line   16)
* allow-keywords option, mysqldump:      mysqldump.          (line  289)
* allow-suspicious-udfs option, mysqld <1>: privileges-options.
                                                             (line   31)
* allow-suspicious-udfs option, mysqld:  server-options.     (line   74)
* ALLOW_INVALID_DATES SQL mode:          server-sql-mode.    (line   86)
* allowold option, mysqlhotcopy:         mysqlhotcopy.       (line   77)
* ALTER COLUMN:                          alter-table.        (line  395)
* ALTER DATABASE:                        alter-database.     (line    6)
* ALTER EVENT:                           alter-event.        (line    6)
* ALTER FUNCTION:                        alter-procedure.    (line    6)
* ALTER LOGFILE GROUP:                   alter-logfile-group.
                                                             (line    6)
* ALTER PROCEDURE:                       alter-procedure.    (line    6)
* ALTER SCHEMA:                          alter-database.     (line    6)
* ALTER SERVER:                          alter-server.       (line    6)
* ALTER TABLE <1>:                       alter-table-problems.
                                                             (line    6)
* ALTER TABLE:                           alter-table.        (line    6)
* ALTER TABLESPACE:                      alter-tablespace.   (line    6)
* ALTER VIEW:                            alter-view.         (line    6)
* altering, database:                    alter-database.     (line    6)
* altering, schema:                      alter-database.     (line    6)
* analyze option, myisamchk:             myisamchk-other-options.
                                                             (line    9)
* analyze option, mysqlcheck:            mysqlcheck.         (line  169)
* ANALYZE TABLE:                         analyze-table.      (line    6)
* Analyzing, thread state:               general-thread-states.
                                                             (line   18)
* AND, bitwise:                          bit-functions.      (line   27)
* AND, logical:                          logical-operators.  (line   46)
* angel-pid-file option, mysqlmanager:   instance-manager-command-options.
                                                             (line   32)
* anonymous user <1>:                    request-access.     (line   27)
* anonymous user <2>:                    connection-access.  (line   96)
* anonymous user:                        default-privileges. (line    6)
* ANSI mode, running:                    ansi-mode.          (line    6)
* ansi option, mysqld:                   server-options.     (line   87)
* ANSI SQL mode:                         server-sql-mode.    (line   55)
* ANSI_QUOTES SQL mode:                  server-sql-mode.    (line  103)
* answering questions, etiquette:        mailing-list-use.   (line    6)
* ANY:                                   any-in-some-subqueries.
                                                             (line    6)
* Apache:                                apache.             (line    6)
* API node (MySQL Cluster), defined:     mysql-cluster-basics.
                                                             (line    6)
* API nodes:                             mysql-cluster-mysqld-process.
                                                             (line    6)
* API's, list of:                        packages.           (line    6)
* APIs:                                  apis.               (line   17)
* APIs, Perl:                            perl.               (line    6)
* apply_status table (OBSOLETE):         mysql-cluster-replication-schema.
                                                             (line   79)
* approximate-value literals:            precision-math.     (line   14)
* ArbitrationDelay <1>:                  mysql-cluster-api-definition.
                                                             (line   66)
* ArbitrationDelay:                      mysql-cluster-mgm-definition.
                                                             (line  111)
* ArbitrationRank <1>:                   mysql-cluster-api-definition.
                                                             (line   52)
* ArbitrationRank:                       mysql-cluster-mgm-definition.
                                                             (line   87)
* ArbitrationTimeout (DEPRECATED):       mysql-cluster-ndbd-definition.
                                                             (line 1267)
* arbitrator:                            faqs-mysql-cluster. (line  113)
* ARCHIVE storage engine <1>:            archive-storage-engine.
                                                             (line    6)
* ARCHIVE storage engine:                storage-engines.    (line   21)
* Area() <1>:                            multipolygon-property-functions.
                                                             (line    8)
* Area():                                polygon-property-functions.
                                                             (line    8)
* argument processing:                   udf-arguments.      (line    6)
* arithmetic expressions:                arithmetic-functions.
                                                             (line   43)
* arithmetic functions:                  bit-functions.      (line    6)
* AS <1>:                                join.               (line    6)
* AS:                                    select.             (line  107)
* AsBinary():                            functions-to-convert-geometries-between-formats.
                                                             (line    9)
* ASCII():                               string-functions.   (line  101)
* ASIN():                                mathematical-functions.
                                                             (line   75)
* AsText():                              functions-to-convert-geometries-between-formats.
                                                             (line   16)
* asynchronous replication:              mysql-cluster-replication.
                                                             (line   19)
* ATAN():                                mathematical-functions.
                                                             (line   98)
* ATAN2():                               mathematical-functions.
                                                             (line  108)
* attackers, security against:           security-against-attack.
                                                             (line    6)
* attribute promotion, ndb_restore:      mysql-cluster-restore.
                                                             (line   72)
* attribute promotion, replication:      replication-features-different-data-types.
                                                             (line   14)
* auto-generate-sql option, mysqlslap:   mysqlslap.          (line  142)
* auto-generate-sql-add-autoincrement option, mysqlslap: mysqlslap.
                                                             (line  147)
* auto-generate-sql-execute-number option, mysqlslap: mysqlslap.
                                                             (line  152)
* auto-generate-sql-guid-primary option, mysqlslap: mysqlslap.
                                                             (line  157)
* auto-generate-sql-load-type option, mysqlslap: mysqlslap.  (line  162)
* auto-generate-sql-secondary-indexes option, mysqlslap: mysqlslap.
                                                             (line  170)
* auto-generate-sql-unique-query-number option, mysqlslap: mysqlslap.
                                                             (line  176)
* auto-generate-sql-unique-write-number option, mysqlslap: mysqlslap.
                                                             (line  184)
* auto-generate-sql-write-number option, mysqlslap: mysqlslap.
                                                             (line  190)
* AUTO-INCREMENT, ODBC:                  myodbc-usagenotes-functionality-last-insert-id.
                                                             (line    6)
* auto-rehash option, mysql:             mysql-command-options.
                                                             (line  130)
* auto-repair option, mysqlcheck:        mysqlcheck.         (line  179)
* AUTO_INCREMENT:                        example-auto-increment.
                                                             (line    6)
* AUTO_INCREMENT, and NULL values:       problems-with-null. (line   71)
* autoclose option, mysqld_safe:         mysqld-safe.        (line  110)
* AVG():                                 group-by-functions. (line   52)
* AVG(DISTINCT):                         group-by-functions. (line   52)
* backslash, escape character:           literals.           (line   15)
* backspace (\b) <1>:                    load-data.          (line  413)
* backspace (\b):                        string-syntax.      (line   51)
* backup identifiers, native backup and restore: mysql-cluster-backup-using-management-client.
                                                             (line   58)
* backup option, myisamchk:              myisamchk-repair-options.
                                                             (line    8)
* backup option, myisampack:             myisampack.         (line   48)
* BACKUP TABLE:                          backup-table.       (line    6)
* BackupDataBufferSize:                  mysql-cluster-backup-configuration.
                                                             (line    8)
* BackupDataBufferSize (MySQL Cluster configuration parameter): mysql-cluster-ndbd-definition.
                                                             (line 1488)
* BackupDataDir:                         mysql-cluster-ndbd-definition.
                                                             (line  134)
* BackupLogBufferSize <1>:               mysql-cluster-backup-configuration.
                                                             (line   13)
* BackupLogBufferSize:                   mysql-cluster-ndbd-definition.
                                                             (line 1502)
* BackupMaxWriteSize <1>:                mysql-cluster-backup-configuration.
                                                             (line   29)
* BackupMaxWriteSize:                    mysql-cluster-ndbd-definition.
                                                             (line 1559)
* BackupMemory <1>:                      mysql-cluster-backup-configuration.
                                                             (line   18)
* BackupMemory:                          mysql-cluster-ndbd-definition.
                                                             (line 1527)
* BackupReportFrequency:                 mysql-cluster-ndbd-definition.
                                                             (line 1540)
* backups:                               backup-and-recovery.
                                                             (line   13)
* backups, database:                     backup-table.       (line    6)
* backups, in MySQL Cluster <1>:         mysql-cluster-backup-configuration.
                                                             (line    6)
* backups, in MySQL Cluster <2>:         mysql-cluster-backup-using-management-client.
                                                             (line    6)
* backups, in MySQL Cluster <3>:         mysql-cluster-backup-concepts.
                                                             (line    6)
* backups, in MySQL Cluster:             mysql-cluster-backup.
                                                             (line   14)
* backups, in MySQL Cluster replication: mysql-cluster-replication-backups.
                                                             (line   10)
* backups, troubleshooting, in MySQL Cluster: mysql-cluster-backup-troubleshooting.
                                                             (line    6)
* BackupWriteSize <1>:                   mysql-cluster-backup-configuration.
                                                             (line   24)
* BackupWriteSize:                       mysql-cluster-ndbd-definition.
                                                             (line 1552)
* base64-output option, mysqlbinlog:     mysqlbinlog.        (line  115)
* basedir option, mysql.server:          mysql-server.       (line   34)
* basedir option, mysql_upgrade:         mysql-upgrade.      (line   73)
* basedir option, mysqld:                server-options.     (line   93)
* basedir option, mysqld_safe:           mysqld-safe.        (line  122)
* batch mode:                            batch-mode.         (line    6)
* batch option, mysql:                   mysql-command-options.
                                                             (line  144)
* BatchByteSize:                         mysql-cluster-api-definition.
                                                             (line   73)
* batched updates (MySQL Cluster Replication): mysql-cluster-replication-starting.
                                                             (line   71)
* BatchSize:                             mysql-cluster-api-definition.
                                                             (line   90)
* BatchSizePerLocalScan:                 mysql-cluster-ndbd-definition.
                                                             (line  570)
* Bazaar tree:                           installing-source-tree.
                                                             (line    6)
* BdMPolyFromText():                     gis-wkt-functions.  (line   59)
* BdMPolyFromWKB():                      gis-wkb-functions.  (line   59)
* BdPolyFromText():                      gis-wkt-functions.  (line   65)
* BdPolyFromWKB():                       gis-wkb-functions.  (line   65)
* BEGIN <1>:                             begin-end.          (line    6)
* BEGIN:                                 commit.             (line    6)
* BEGIN, XA transactions:                xa-statements.      (line    6)
* benchmark suite:                       mysql-benchmarks.   (line    6)
* BENCHMARK():                           information-functions.
                                                             (line   30)
* benchmarks:                            custom-benchmarks.  (line    6)
* BETWEEN ... AND:                       comparison-operators.
                                                             (line  172)
* big-tables option, mysqld:             server-options.     (line  106)
* big5:                                  faqs-cjk.           (line   20)
* BIGINT data type:                      numeric-type-overview.
                                                             (line  127)
* BIN():                                 string-functions.   (line  116)
* BINARY:                                cast-functions.     (line   11)
* BINARY data type <1>:                  binary-varbinary.   (line    6)
* BINARY data type:                      string-type-overview.
                                                             (line  139)
* binary distributions:                  mysql-binaries.     (line    6)
* binary distributions, installing:      installing-binary.  (line    6)
* binary distributions, on Linux:        binary-notes-linux. (line    6)
* binary log:                            binary-log.         (line   13)
* binary logging, and MySQL Cluster:     mysql-cluster-limitations-exclusive-to-cluster.
                                                             (line   26)
* bind-address option, mysqld:           server-options.     (line  123)
* bind-address option, mysqlmanager:     instance-manager-command-options.
                                                             (line   46)
* Binlog Dump, thread command:           thread-commands.    (line    8)
* binlog-do-db option, mysqld:           binary-log.         (line  124)
* binlog-format option, mysqld:          server-options.     (line  132)
* binlog-ignore-db option, mysqld:       binary-log.         (line  145)
* binlog-row-event-max-size option, mysqld: server-options.  (line  177)
* binlog_index table (OBSOLETE):         mysql-cluster-replication-schema.
                                                             (line    6)
* BIT data type:                         numeric-type-overview.
                                                             (line   35)
* BIT_AND():                             group-by-functions. (line   63)
* BIT_COUNT:                             calculating-days.   (line    6)
* BIT_COUNT():                           bit-functions.      (line   76)
* bit_functions, example:                calculating-days.   (line    6)
* BIT_LENGTH():                          string-functions.   (line  125)
* BIT_OR:                                calculating-days.   (line    6)
* BIT_OR():                              group-by-functions. (line   72)
* BIT_XOR():                             group-by-functions. (line   79)
* BitKeeper tree:                        installing-source-tree.
                                                             (line    6)
* BLACKHOLE storage engine <1>:          blackhole-storage-engine.
                                                             (line    6)
* BLACKHOLE storage engine:              storage-engines.    (line   21)
* BLOB columns, default values:          blob.               (line   49)
* BLOB columns, indexing <1>:            create-table.       (line  427)
* BLOB columns, indexing:                indexes.            (line   15)
* BLOB data type <1>:                    blob.               (line    6)
* BLOB data type:                        string-type-overview.
                                                             (line  165)
* BLOB, inserting binary data:           string-syntax.      (line  133)
* BLOB, size:                            storage-requirements.
                                                             (line  140)
* block-search option, myisamchk:        myisamchk-other-options.
                                                             (line   24)
* BOOL data type:                        numeric-type-overview.
                                                             (line   45)
* BOOLEAN data type:                     numeric-type-overview.
                                                             (line   45)
* bootstrap option, mysqld:              server-options.     (line  191)
* Borland Builder 4:                     myodbc-usagenotes-apptips-borland-builder.
                                                             (line    6)
* Boundary():                            general-geometry-property-functions.
                                                             (line   70)
* brackets, square:                      data-types.         (line   40)
* brief option, mysqlaccess:             mysqlaccess.        (line   63)
* buffer sizes, client:                  apis.               (line   17)
* buffer sizes, mysqld server:           server-parameters.  (line    6)
* Buffer():                              spatial-operators.  (line   12)
* bug reports, criteria for:             bug-reports.        (line    6)
* bugs database:                         bug-reports.        (line    6)
* bugs, known:                           bugs.               (line   11)
* bugs, reporting:                       bug-reports.        (line    6)
* bugs.mysql.com:                        bug-reports.        (line    6)
* building, client programs:             building-clients.   (line    6)
* C API, data types:                     c.                  (line   25)
* C API, functions:                      c-api-function-overview.
                                                             (line    6)
* C API, linking problems:               c-api-linking-problems.
                                                             (line    6)
* C prepared statement API, functions:   c-api-prepared-statement-function-overview.
                                                             (line    6)
* C++ APIs:                              cplusplus.          (line    6)
* C++ Builder:                           myodbc-usagenotes-apptips-borland-cppbuilder.
                                                             (line    6)
* C++ compiler cannot create executables: compilation-problems.
                                                             (line   63)
* C++ compiler, gcc:                     configure-options.  (line  349)
* C:\my.cnf file:                        multiple-server-clients.
                                                             (line   34)
* CACHE INDEX:                           cache-index.        (line    6)
* CACHE INDEX, and partitioning:         partitioning-limitations.
                                                             (line  296)
* caches, clearing:                      flush.              (line    6)
* calculating, dates:                    date-calculations.  (line    6)
* calendar:                              mysql-calendar.     (line    6)
* CALL:                                  call.               (line    6)
* calling sequences for aggregate functions, UDF: udf-aggr-calling.
                                                             (line    6)
* calling sequences for simple functions, UDF: udf-calling.  (line    6)
* can't create/write to file:            cannot-create.      (line    6)
* carriage return (\r) <1>:              load-data.          (line  415)
* carriage return (\r):                  string-syntax.      (line   53)
* CASE <1>:                              case-statement.     (line    6)
* CASE:                                  control-flow-functions.
                                                             (line   12)
* case sensitivity, in access checking:  privileges.         (line  186)
* case sensitivity, in identifiers:      identifier-case-sensitivity.
                                                             (line    6)
* case sensitivity, in names:            identifier-case-sensitivity.
                                                             (line    6)
* case sensitivity, in searches:         case-sensitivity.   (line    6)
* case sensitivity, in string comparisons: string-comparison-functions.
                                                             (line   15)
* case-sensitivity, of database names:   extensions-to-ansi. (line   38)
* case-sensitivity, of table names:      extensions-to-ansi. (line   38)
* CAST:                                  cast-functions.     (line   37)
* cast functions:                        cast-functions.     (line    6)
* cast operators:                        cast-functions.     (line    6)
* casts <1>:                             cast-functions.     (line    6)
* casts <2>:                             comparison-operators.
                                                             (line   36)
* casts:                                 type-conversion.    (line    6)
* CC environment variable <1>:           environment-variables.
                                                             (line   18)
* CC environment variable <2>:           compilation-problems.
                                                             (line  108)
* CC environment variable:               configure-options.  (line  349)
* cc1plus problems:                      compilation-problems.
                                                             (line   38)
* CEIL():                                mathematical-functions.
                                                             (line  120)
* CEILING():                             mathematical-functions.
                                                             (line  124)
* Centroid():                            multipolygon-property-functions.
                                                             (line   26)
* CFLAGS environment variable <1>:       environment-variables.
                                                             (line   18)
* CFLAGS environment variable <2>:       compilation-problems.
                                                             (line  108)
* CFLAGS environment variable:           configure-options.  (line  363)
* CHANGE MASTER TO:                      change-master-to.   (line    6)
* CHANGE MASTER TO, in MySQL Cluster:    mysql-cluster-replication-preparation.
                                                             (line   39)
* Change user, thread command:           thread-commands.    (line   13)
* ChangeLog:                             news.               (line   16)
* changes to privileges:                 request-access.     (line  166)
* changes, log:                          news.               (line   16)
* changes, MySQL 5.1:                    news-5-1-x.         (line   38)
* changes, MySQL Cluster:                mysql-cluster-news. (line   12)
* Changing master, thread state:         slave-connection-thread-states.
                                                             (line    9)
* changing socket location <1>:          problems-with-mysql-sock.
                                                             (line   26)
* changing socket location <2>:          automatic-start.    (line  120)
* changing socket location:              configure-options.  (line  329)
* changing, column:                      alter-table.        (line  395)
* changing, column order:                change-column-order.
                                                             (line    6)
* changing, field:                       alter-table.        (line  395)
* changing, table <1>:                   alter-table-problems.
                                                             (line    6)
* changing, table:                       alter-table.        (line    6)
* CHAR data type <1>:                    string-types.       (line   14)
* CHAR data type:                        string-type-overview.
                                                             (line   80)
* CHAR VARYING data type:                string-type-overview.
                                                             (line  110)
* CHAR():                                string-functions.   (line  132)
* CHAR_LENGTH():                         string-functions.   (line  174)
* CHARACTER data type:                   string-type-overview.
                                                             (line   80)
* character sets:                        charset-configuration.
                                                             (line   10)
* Character sets:                        charset.            (line   20)
* character sets:                        configure-options.  (line  407)
* character sets, adding:                adding-character-set.
                                                             (line   12)
* CHARACTER VARYING data type:           string-type-overview.
                                                             (line  110)
* character-set-client-handshake option, mysqld: server-options.
                                                             (line  212)
* character-set-filesystem option, mysqld: server-options.   (line  223)
* character-set-server option, mysqld:   server-options.     (line  238)
* character-sets-dir option, myisamchk:  myisamchk-repair-options.
                                                             (line   12)
* character-sets-dir option, myisampack: myisampack.         (line   53)
* character-sets-dir option, mysql:      mysql-command-options.
                                                             (line  154)
* character-sets-dir option, mysqladmin: mysqladmin.         (line  298)
* character-sets-dir option, mysqlbinlog: mysqlbinlog.       (line  122)
* character-sets-dir option, mysqlcheck: mysqlcheck.         (line  184)
* character-sets-dir option, mysqld:     server-options.     (line  199)
* character-sets-dir option, mysqldump:  mysqldump.          (line  294)
* character-sets-dir option, mysqlimport: mysqlimport.       (line  110)
* character-sets-dir option, mysqlshow:  mysqlshow.          (line  101)
* CHARACTER_LENGTH():                    string-functions.   (line  181)
* CHARACTER_SETS, INFORMATION_SCHEMA table: character-sets-table.
                                                             (line    6)
* characters, multi-byte:                multi-byte-characters.
                                                             (line    6)
* charset command, mysql:                mysql-commands.     (line   61)
* charset option, comp_err:              comp-err.           (line   28)
* CHARSET():                             information-functions.
                                                             (line   76)
* check option, myisamchk:               myisamchk-check-options.
                                                             (line    9)
* check option, mysqlcheck:              mysqlcheck.         (line  189)
* check options, myisamchk:              myisamchk-check-options.
                                                             (line    6)
* CHECK TABLE:                           check-table.        (line    6)
* check-only-changed option, myisamchk:  myisamchk-check-options.
                                                             (line   14)
* check-only-changed option, mysqlcheck: mysqlcheck.         (line  193)
* check-password-file option, mysqlmanager: instance-manager-command-options.
                                                             (line   50)
* check-upgrade option, mysqlcheck:      mysqlcheck.         (line  198)
* Checking master version, thread state: slave-io-thread-states.
                                                             (line   19)
* Checking table, thread state:          general-thread-states.
                                                             (line   23)
* checking, tables for errors:           check.              (line    6)
* CHECKPOINT Events (MySQL Cluster):     mysql-cluster-log-events.
                                                             (line   35)
* checkpoint option, mysqlhotcopy:       mysqlhotcopy.       (line   82)
* Checksum:                              mysql-cluster-tcp-definition.
                                                             (line   56)
* Checksum (MySQL Cluster) <1>:          mysql-cluster-sci-definition.
                                                             (line   76)
* Checksum (MySQL Cluster):              mysql-cluster-shm-definition.
                                                             (line   49)
* checksum errors:                       solaris.            (line   11)
* CHECKSUM TABLE:                        checksum-table.     (line    6)
* Chinese, Japanese, Korean character sets, frequently asked questions: faqs-cjk.
                                                             (line    6)
* choosing types:                        choosing-types.     (line    6)
* choosing, a MySQL version:             which-version.      (line   19)
* chroot option, mysqld:                 server-options.     (line  253)
* chroot option, mysqlhotcopy:           mysqlhotcopy.       (line   87)
* circular replication, in MySQL Cluster: mysql-cluster-replication-issues.
                                                             (line   56)
* CJK (Chinese, Japanese, Korean), Access, PHP, etc.: faqs-cjk.
                                                             (line   48)
* CJK (Chinese, Japanese, Korean), availability of specific characters: faqs-cjk.
                                                             (line   61)
* CJK (Chinese, Japanese, Korean), available character sets: faqs-cjk.
                                                             (line   11)
* CJK (Chinese, Japanese, Korean), big5: faqs-cjk.           (line   20)
* CJK (Chinese, Japanese, Korean), character sets available: faqs-cjk.
                                                             (line   13)
* CJK (Chinese, Japanese, Korean), characters displayed as question marks: faqs-cjk.
                                                             (line   10)
* CJK (Chinese, Japanese, Korean), CJKV: faqs-cjk.           (line   78)
* CJK (Chinese, Japanese, Korean), collations: faqs-cjk.     (line   68)
* CJK (Chinese, Japanese, Korean), conversion problems with Japanese character sets: faqs-cjk.
                                                             (line   23)
* CJK (Chinese, Japanese, Korean), data truncation: faqs-cjk.
                                                             (line   44)
* CJK (Chinese, Japanese, Korean), Database and table names: faqs-cjk.
                                                             (line   82)
* CJK (Chinese, Japanese, Korean), documentation in Chinese: faqs-cjk.
                                                             (line   87)
* CJK (Chinese, Japanese, Korean), documentation in Japanese: faqs-cjk.
                                                             (line   89)
* CJK (Chinese, Japanese, Korean), documentation in Korean: faqs-cjk.
                                                             (line   89)
* CJK (Chinese, Japanese, Korean), gb2312, gbk: faqs-cjk.    (line   13)
* CJK (Chinese, Japanese, Korean), Japanese character sets: faqs-cjk.
                                                             (line   25)
* CJK (Chinese, Japanese, Korean), Korean character set: faqs-cjk.
                                                             (line   39)
* CJK (Chinese, Japanese, Korean), LIKE and FULLTEXT: faqs-cjk.
                                                             (line   58)
* CJK (Chinese, Japanese, Korean), MySQL 4.0 behavior: faqs-cjk.
                                                             (line   51)
* CJK (Chinese, Japanese, Korean), ORDER BY treatment: faqs-cjk.
                                                             (line   68)
* CJK (Chinese, Japanese, Korean), problems with Access, PHP, etc.: faqs-cjk.
                                                             (line   46)
* CJK (Chinese, Japanese, Korean), problems with Big5 character sets (Chinese): faqs-cjk.
                                                             (line   18)
* CJK (Chinese, Japanese, Korean), problems with data truncation: faqs-cjk.
                                                             (line   42)
* CJK (Chinese, Japanese, Korean), problems with euckr character set (Korean): faqs-cjk.
                                                             (line   37)
* CJK (Chinese, Japanese, Korean), problems with GB character sets (Chinese): faqs-cjk.
                                                             (line   13)
* CJK (Chinese, Japanese, Korean), problems with LIKE and FULLTEXT: faqs-cjk.
                                                             (line   56)
* CJK (Chinese, Japanese, Korean), problems with Yen sign (Japanese): faqs-cjk.
                                                             (line   30)
* CJK (Chinese, Japanese, Korean), rejected characters: faqs-cjk.
                                                             (line   74)
* CJK (Chinese, Japanese, Korean), sort order problems: faqs-cjk.
                                                             (line   68)
* CJK (Chinese, Japanese, Korean), sorting problems: faqs-cjk.
                                                             (line   66)
* CJK (Chinese, Japanese, Korean), testing availability of characters: faqs-cjk.
                                                             (line   63)
* CJK (Chinese, Japanese, Korean), Unicode collations: faqs-cjk.
                                                             (line   72)
* CJK (Chinese, Japanese, Korean), Vietnamese: faqs-cjk.     (line   80)
* CJK (Chinese, Japanese, Korean), Yen sign: faqs-cjk.       (line   32)
* CJK, FAQ:                              faqs-cjk.           (line    6)
* clean-password-file option, mysqlmanager: instance-manager-command-options.
                                                             (line   55)
* cleaning up, thread state:             general-thread-states.
                                                             (line   27)
* clear command, mysql:                  mysql-commands.     (line   70)
* clearing, caches:                      flush.              (line    6)
* Clearing, thread state:                event-scheduler-thread-states.
                                                             (line   10)
* client connection threads:             connection-threads. (line    6)
* client programs:                       programs-overview.  (line  119)
* client programs, building:             building-clients.   (line    6)
* client tools:                          apis.               (line   17)
* clients, debugging:                    debugging-client.   (line    6)
* clients, threaded:                     threaded-clients.   (line    6)
* CLOSE:                                 close.              (line    6)
* Close stmt, thread command:            thread-commands.    (line   17)
* closing tables, thread state:          general-thread-states.
                                                             (line   32)
* closing, tables:                       table-cache.        (line    6)
* cluster database (OBSOLETE):           mysql-cluster-replication-schema.
                                                             (line    6)
* cluster logs <1>:                      mysql-cluster-logging-management-commands.
                                                             (line    6)
* cluster logs:                          mysql-cluster-event-reports.
                                                             (line   12)
* cluster.binlog_index table (OBSOLETE): mysql-cluster-replication-schema.
                                                             (line    6)
* cluster_replication database (OBSOLETE): mysql-cluster-replication-schema.
                                                             (line    6)
* Clustering:                            mysql-cluster.      (line   26)
* CLUSTERLOG commands (MySQL Cluster):   mysql-cluster-logging-management-commands.
                                                             (line    8)
* CLUSTERLOG STATISTICS command (MySQL Cluster): mysql-cluster-log-statistics.
                                                             (line    6)
* CMake:                                 windows-source-build-cmake.
                                                             (line    6)
* COALESCE():                            comparison-operators.
                                                             (line  201)
* COERCIBILITY():                        information-functions.
                                                             (line   87)
* ColdFusion:                            myodbc-usagenotes-apptips-coldfusion.
                                                             (line    6)
* collating, strings:                    string-collating.   (line    6)
* COLLATION():                           information-functions.
                                                             (line  113)
* collation, adding:                     adding-collation.   (line   13)
* collation-server option, mysqld:       server-options.     (line  263)
* COLLATION_CHARACTER_SET_APPLICABILITY, INFORMATION_SCHEMA table: collation-character-set-applicability-table.
                                                             (line    6)
* COLLATIONS, INFORMATION_SCHEMA table:  collations-table.   (line    6)
* column comments:                       create-table.       (line  315)
* column format:                         create-table.       (line  319)
* column names, case sensitivity:        identifier-case-sensitivity.
                                                             (line    6)
* column storage:                        create-table.       (line  335)
* column, changing:                      alter-table.        (line  395)
* column, types:                         data-types.         (line   29)
* column-names option, mysql:            mysql-command-options.
                                                             (line  159)
* column-type-info option, mysql:        mysql-command-options.
                                                             (line  163)
* COLUMN_PRIVILEGES, INFORMATION_SCHEMA table: column-privileges-table.
                                                             (line    6)
* columns option, mysqlimport:           mysqlimport.        (line  115)
* columns, changing:                     change-column-order.
                                                             (line    6)
* columns, indexes:                      indexes.            (line    6)
* COLUMNS, INFORMATION_SCHEMA table:     columns-table.      (line    6)
* columns, names:                        identifiers.        (line   13)
* columns, other types:                  other-vendor-data-types.
                                                             (line    6)
* columns, selecting:                    selecting-columns.  (line    6)
* columns, storage requirements:         storage-requirements.
                                                             (line    6)
* comma-separated values data, reading <1>: select.          (line  356)
* comma-separated values data, reading:  load-data.          (line  300)
* command options (MySQL Cluster):       mysql-cluster-command-options.
                                                             (line   12)
* command options (MySQL Cluster), mysqld: mysql-cluster-mysqld-command-options.
                                                             (line    6)
* command options (MySQL Cluster), ndb_mgm: mysql-cluster-ndb-mgm-command-options.
                                                             (line    6)
* command options (MySQL Cluster), ndb_mgmd: mysql-cluster-ndb-mgmd-command-options.
                                                             (line    6)
* command options (MySQL Cluster), ndbd: mysql-cluster-ndbd-command-options.
                                                             (line    6)
* command options, mysql:                mysql-command-options.
                                                             (line    6)
* command options, mysqladmin:           mysqladmin.         (line  226)
* command options, mysqld:               server-options.     (line    6)
* command syntax:                        manual-conventions. (line  111)
* command-line history, mysql:           mysql-command-options.
                                                             (line  566)
* commands out of sync:                  commands-out-of-sync.
                                                             (line    6)
* commands, for binary distribution:     installing-binary.  (line   39)
* Comment syntax:                        comments.           (line    6)
* comments option, mysql:                mysql-command-options.
                                                             (line  169)
* comments option, mysqldump:            mysqldump.          (line  299)
* comments, adding:                      comments.           (line    6)
* comments, starting:                    ansi-diff-comments. (line    6)
* COMMIT <1>:                            commit.             (line    6)
* COMMIT:                                ansi-diff-transactions.
                                                             (line    6)
* commit option, mysqlaccess:            mysqlaccess.        (line   67)
* commit option, mysqlslap:              mysqlslap.          (line  195)
* COMMIT, XA transactions:               xa-statements.      (line    6)
* Committing events to binlog, thread state: mysql-cluster-thread-states.
                                                             (line    6)
* comp_err:                              programs-overview.  (line   64)
* comp_err, charset option:              comp-err.           (line   28)
* comp_err, debug option:                comp-err.           (line   33)
* comp_err, debug-info option:           comp-err.           (line   38)
* comp_err, header_file option:          comp-err.           (line   42)
* comp_err, help option:                 comp-err.           (line   24)
* comp_err, in_file option:              comp-err.           (line   46)
* comp_err, name_file option:            comp-err.           (line   51)
* comp_err, out_dir option:              comp-err.           (line   55)
* comp_err, out_file option:             comp-err.           (line   60)
* comp_err, statefile option:            comp-err.           (line   64)
* comp_err, version option:              comp-err.           (line   69)
* compact option, mysqldump:             mysqldump.          (line  306)
* comparison operators:                  comparison-operators.
                                                             (line    6)
* compatibility, between MySQL versions: upgrading-from-5-0. (line    6)
* compatibility, with mSQL:              string-comparison-functions.
                                                             (line  148)
* compatibility, with ODBC <1>:          join.               (line  145)
* compatibility, with ODBC <2>:          create-table.       (line  275)
* compatibility, with ODBC <3>:          comparison-operators.
                                                             (line  144)
* compatibility, with ODBC <4>:          type-conversion.    (line   40)
* compatibility, with ODBC <5>:          numeric-type-overview.
                                                             (line  223)
* compatibility, with ODBC:              identifier-qualifiers.
                                                             (line   41)
* compatibility, with Oracle <1>:        describe.           (line   37)
* compatibility, with Oracle <2>:        group-by-functions. (line  226)
* compatibility, with Oracle:            extensions-to-ansi. (line   94)
* compatibility, with PostgreSQL:        extensions-to-ansi. (line  185)
* compatibility, with standard SQL:      compatibility.      (line   15)
* compatibility, with Sybase:            use.                (line   27)
* compatible option, mysqldump:          mysqldump.          (line  321)
* compiler, C++ gcc:                     configure-options.  (line  349)
* compiling, on Windows:                 windows-client-compiling.
                                                             (line    6)
* compiling, optimizing:                 system-optimization.
                                                             (line    6)
* compiling, problems:                   compilation-problems.
                                                             (line    6)
* compiling, speed:                      compile-and-link-options.
                                                             (line    6)
* compiling, statically:                 configure-options.  (line  341)
* compiling, user-defined functions:     udf-compiling.      (line    6)
* complete-insert option, mysqldump:     mysqldump.          (line  341)
* compliance, Y2K:                       y2k-issues.         (line    6)
* composite partitioning:                partitioning-subpartitions.
                                                             (line   26)
* compress option, mysql:                mysql-command-options.
                                                             (line  176)
* compress option, mysqladmin:           mysqladmin.         (line  303)
* compress option, mysqlcheck:           mysqlcheck.         (line  206)
* compress option, mysqldump:            mysqldump.          (line  345)
* compress option, mysqlimport:          mysqlimport.        (line  121)
* compress option, mysqlshow:            mysqlshow.          (line  106)
* compress option, mysqlslap:            mysqlslap.          (line  200)
* COMPRESS():                            encryption-functions.
                                                             (line   80)
* compressed tables:                     compressed-format.  (line    6)
* CompressedBackup:                      mysql-cluster-ndbd-definition.
                                                             (line  877)
* CompressedLCP:                         mysql-cluster-ndbd-definition.
                                                             (line  896)
* CONCAT():                              string-functions.   (line  185)
* CONCAT_WS():                           string-functions.   (line  206)
* concurrency option, mysqlslap:         mysqlslap.          (line  205)
* concurrent inserts <1>:                concurrent-inserts. (line    6)
* concurrent inserts:                    internal-locking.   (line   71)
* Conditions:                            declare-conditions. (line    6)
* config-file option, my_print_defaults: my-print-defaults.  (line   27)
* config-file option, mysqld_multi:      mysqld-multi.       (line   85)
* config-file option, ndb_config:        mysql-cluster-utilities-ndb-config.
                                                             (line   40)
* config.cache:                          compilation-problems.
                                                             (line   15)
* config.cache file:                     compilation-problems.
                                                             (line    6)
* config.ini (MySQL Cluster) <1>:        mysql-cluster-ndb-mgmd-process.
                                                             (line   26)
* config.ini (MySQL Cluster) <2>:        mysql-cluster-config-example.
                                                             (line    6)
* config.ini (MySQL Cluster) <3>:        mysql-cluster-config-file.
                                                             (line   19)
* config.ini (MySQL Cluster):            mysql-cluster-multi-config.
                                                             (line    6)
* configuration files:                   access-denied.      (line  101)
* configuration options:                 configure-options.  (line    6)
* configuration, MySQL Cluster:          mysql-cluster-config-params-overview.
                                                             (line   12)
* configure option, -with-low-memory:    compilation-problems.
                                                             (line   38)
* configure script:                      configure-options.  (line    6)
* configure, disable-grant-options option: configure-options.
                                                             (line  501)
* configure, enable-thread-safe-client option: configure-options.
                                                             (line  476)
* configure, localstatedir option:       configure-options.  (line  308)
* configure, prefix option:              configure-options.  (line  308)
* configure, running after prior invocation: compilation-problems.
                                                             (line   15)
* configure, with-big-tables option:     configure-options.  (line  491)
* configure, with-charset option:        configure-options.  (line  407)
* configure, with-collation option:      configure-options.  (line  407)
* configure, with-debug option:          configure-options.  (line  459)
* configure, with-embedded-server option: configure-options. (line  305)
* configure, with-extra-charsets option: configure-options.  (line  407)
* configure, with-unix-socket-path option: configure-options.
                                                             (line  329)
* configure, with-zlib-dir option:       configure-options.  (line  482)
* configure, without-server option:      configure-options.  (line  291)
* configuring backups, in MySQL Cluster: mysql-cluster-backup-configuration.
                                                             (line    6)
* configuring MySQL Cluster <1>:         mysql-cluster-ndb-mgmd-process.
                                                             (line   26)
* configuring MySQL Cluster <2>:         mysql-cluster-mysqld-process.
                                                             (line   32)
* configuring MySQL Cluster <3>:         mysql-cluster-configuration.
                                                             (line   15)
* configuring MySQL Cluster:             mysql-cluster-multi-computer.
                                                             (line   15)
* Configuring MySQL Cluster (concepts):  mysql-cluster-basics.
                                                             (line    6)
* conflict resolution, enabling:         mysql-cluster-replication-conflict-resolution.
                                                             (line  103)
* conflict resolution, in MySQL Cluster Replication: mysql-cluster-replication-conflict-resolution.
                                                             (line    6)
* conflict resolution, mysqld startup options: mysql-cluster-replication-conflict-resolution.
                                                             (line   74)
* connect command, mysql:                mysql-commands.     (line   75)
* Connect Out, thread command:           thread-commands.    (line   25)
* Connect, thread command:               thread-commands.    (line   21)
* connect_timeout variable <1>:          mysqladmin.         (line  421)
* connect_timeout variable:              mysql-command-options.
                                                             (line  541)
* Connecting to master, thread state:    slave-io-thread-states.
                                                             (line   15)
* connecting, remotely with SSH:         windows-and-ssh.    (line    6)
* connecting, to the server <1>:         connecting.         (line    6)
* connecting, to the server:             connecting-disconnecting.
                                                             (line    6)
* connecting, verification:              connection-access.  (line    6)
* CONNECTION Events (MySQL Cluster):     mysql-cluster-log-events.
                                                             (line   20)
* connection, aborted:                   communication-errors.
                                                             (line    6)
* CONNECTION_ID():                       information-functions.
                                                             (line  122)
* Connector/JDBC:                        connectors.         (line   15)
* Connector/MXJ:                         connectors.         (line   15)
* Connector/NET <1>:                     connector-net.      (line   15)
* Connector/NET:                         connectors.         (line   15)
* Connector/NET, reporting problems:     connect-net-support.
                                                             (line   12)
* Connector/ODBC <1>:                    myodbc-connector.   (line   17)
* Connector/ODBC:                        connectors.         (line   15)
* Connector/ODBC, Borland:               myodbc-usagenotes-apptips-borland.
                                                             (line   12)
* Connector/ODBC, Borland Database Engine: myodbc-usagenotes-apptips-borland.
                                                             (line   12)
* Connector/ODBC, reporting problems:    myodbc-support.     (line   14)
* Connectors, MySQL:                     connectors.         (line   15)
* connectstring:                         mysql-cluster-connectstring.
                                                             (line    6)
* console option, mysqld:                server-options.     (line  276)
* const table, optimizer <1>:            select.             (line  429)
* const table, optimizer:                using-explain.      (line  126)
* constant table:                        where-optimizations.
                                                             (line   50)
* constraints:                           constraints.        (line   12)
* CONSTRAINTS, INFORMATION_SCHEMA table: table-constraints-table.
                                                             (line    6)
* Contains():                            functions-that-test-spatial-relationships-between-geometries.
                                                             (line   21)
* contributing companies, list of:       supporters.         (line    6)
* contributors, list of:                 contributors.       (line    6)
* control access:                        connection-access.  (line    6)
* control flow functions:                control-flow-functions.
                                                             (line    6)
* CONV():                                mathematical-functions.
                                                             (line  137)
* conventions, typographical:            manual-conventions. (line    8)
* CONVERT:                               cast-functions.     (line   43)
* CONVERT TO:                            alter-table.        (line  543)
* CONVERT_TZ():                          date-and-time-functions.
                                                             (line  158)
* converting HEAP to MyISAM, thread state: general-thread-states.
                                                             (line   39)
* ConvexHull():                          spatial-operators.  (line   17)
* copy option, mysqlaccess:              mysqlaccess.        (line   74)
* copy to tmp table, thread state:       general-thread-states.
                                                             (line   44)
* copying databases:                     upgrading-to-arch.  (line    6)
* copying tables:                        create-table.       (line 1134)
* Copying to group table, thread state:  general-thread-states.
                                                             (line   50)
* Copying to tmp table on disk, thread state: general-thread-states.
                                                             (line   59)
* Copying to tmp table, thread state:    general-thread-states.
                                                             (line   55)
* core-file option, mysqld:              server-options.     (line  286)
* core-file-size option, mysqld_safe:    mysqld-safe.        (line  126)
* correct-checksum option, myisamchk:    myisamchk-repair-options.
                                                             (line   17)
* correlated subqueries:                 correlated-subqueries.
                                                             (line    6)
* COS():                                 mathematical-functions.
                                                             (line  157)
* COT():                                 mathematical-functions.
                                                             (line  164)
* count option, myisam_ftdump:           myisam-ftdump.      (line   51)
* count option, mysqladmin:              mysqladmin.         (line  308)
* count option, mysqlshow:               mysqlshow.          (line  111)
* COUNT():                               group-by-functions. (line   86)
* COUNT(DISTINCT):                       group-by-functions. (line  116)
* counting, table rows:                  counting-rows.      (line    6)
* CR_SERVER_GONE_ERROR:                  gone-away.          (line    6)
* CR_SERVER_LOST_ERROR:                  gone-away.          (line    6)
* crash:                                 debugging-server.   (line   16)
* crash, recovery:                       crash-recovery.     (line    6)
* crash, repeated:                       crashing.           (line    6)
* crash-me:                              mysql-benchmarks.   (line   43)
* crash-me program <1>:                  mysql-benchmarks.   (line    6)
* crash-me program:                      portability.        (line    6)
* CRC32():                               mathematical-functions.
                                                             (line  173)
* CREATE DATABASE:                       create-database.    (line    6)
* Create DB, thread command:             thread-commands.    (line   29)
* CREATE EVENT:                          create-event.       (line    6)
* CREATE FUNCTION <1>:                   create-procedure.   (line    6)
* CREATE FUNCTION:                       create-function-udf.
                                                             (line    6)
* CREATE INDEX:                          create-index.       (line    6)
* CREATE LOGFILE GROUP:                  create-logfile-group.
                                                             (line    6)
* create option, mysqlslap:              mysqlslap.          (line  210)
* CREATE PROCEDURE:                      create-procedure.   (line    6)
* CREATE SCHEMA:                         create-database.    (line    6)
* CREATE SERVER:                         create-server.      (line    6)
* CREATE TABLE:                          create-table.       (line   10)
* CREATE TABLESPACE:                     create-tablespace.  (line    6)
* CREATE TRIGGER:                        create-trigger.     (line    6)
* CREATE USER:                           create-user.        (line    6)
* CREATE VIEW:                           create-view.        (line    6)
* create-options option, mysqldump:      mysqldump.          (line  350)
* create-schema option, mysqlslap:       mysqlslap.          (line  215)
* Creating delayed handler, thread state: delayed-insert-thread-states.
                                                             (line   21)
* Creating index, thread state:          general-thread-states.
                                                             (line   66)
* Creating sort index, thread state:     general-thread-states.
                                                             (line   71)
* Creating table from master dump, thread state: slave-connection-thread-states.
                                                             (line   13)
* creating table, thread state:          general-thread-states.
                                                             (line   76)
* Creating tmp table, thread state:      general-thread-states.
                                                             (line   81)
* creating user accounts:                create-user.        (line    6)
* creating, bug reports:                 bug-reports.        (line    6)
* creating, database:                    create-database.    (line    6)
* creating, databases:                   database-use.       (line   13)
* creating, default startup options:     option-files.       (line   11)
* creating, function:                    create-function-udf.
                                                             (line    6)
* creating, schema:                      create-database.    (line    6)
* creating, tables:                      creating-tables.    (line    6)
* CROSS JOIN:                            join.               (line    6)
* Crosses():                             functions-that-test-spatial-relationships-between-geometries.
                                                             (line   26)
* CSV data, reading <1>:                 select.             (line  356)
* CSV data, reading:                     load-data.          (line  300)
* csv option, mysqlslap:                 mysqlslap.          (line  220)
* CSV storage engine <1>:                csv-storage-engine. (line   11)
* CSV storage engine:                    storage-engines.    (line   21)
* CURDATE():                             date-and-time-functions.
                                                             (line  186)
* CURRENT_DATE:                          date-and-time-functions.
                                                             (line  197)
* CURRENT_TIME:                          date-and-time-functions.
                                                             (line  213)
* CURRENT_TIMESTAMP:                     date-and-time-functions.
                                                             (line  217)
* CURRENT_USER():                        information-functions.
                                                             (line  131)
* Cursors:                               cursors.            (line   13)
* CURTIME():                             date-and-time-functions.
                                                             (line  201)
* customers, of MySQL:                   internal-use.       (line    6)
* CXX environment variable <1>:          environment-variables.
                                                             (line   18)
* CXX environment variable <2>:          compilation-problems.
                                                             (line   66)
* CXX environment variable:              configure-options.  (line  349)
* CXXFLAGS environment variable <1>:     environment-variables.
                                                             (line   18)
* CXXFLAGS environment variable <2>:     compilation-problems.
                                                             (line  108)
* CXXFLAGS environment variable:         configure-options.  (line  363)
* Daemon, thread command:                thread-commands.    (line   33)
* data node (MySQL Cluster), defined:    mysql-cluster-basics.
                                                             (line    6)
* Data truncation with CJK characters:   faqs-cjk.           (line   44)
* data type, BIGINT:                     numeric-type-overview.
                                                             (line  127)
* data type, BINARY <1>:                 binary-varbinary.   (line    6)
* data type, BINARY:                     string-type-overview.
                                                             (line  139)
* data type, BIT:                        numeric-type-overview.
                                                             (line   35)
* data type, BLOB <1>:                   blob.               (line    6)
* data type, BLOB:                       string-type-overview.
                                                             (line  165)
* data type, BOOL <1>:                   other-vendor-data-types.
                                                             (line    6)
* data type, BOOL:                       numeric-type-overview.
                                                             (line   45)
* data type, BOOLEAN <1>:                other-vendor-data-types.
                                                             (line    6)
* data type, BOOLEAN:                    numeric-type-overview.
                                                             (line   45)
* data type, CHAR <1>:                   string-types.       (line   14)
* data type, CHAR:                       string-type-overview.
                                                             (line   80)
* data type, CHAR VARYING:               string-type-overview.
                                                             (line  110)
* data type, CHARACTER:                  string-type-overview.
                                                             (line   80)
* data type, CHARACTER VARYING:          string-type-overview.
                                                             (line  110)
* data type, DATE <1>:                   datetime.           (line   10)
* data type, DATE:                       date-and-time-type-overview.
                                                             (line   14)
* data type, DATETIME <1>:               datetime.           (line   10)
* data type, DATETIME:                   date-and-time-type-overview.
                                                             (line   21)
* data type, DEC:                        numeric-type-overview.
                                                             (line  241)
* data type, DECIMAL <1>:                precision-math.     (line   14)
* data type, DECIMAL:                    numeric-type-overview.
                                                             (line  225)
* data type, DOUBLE:                     numeric-type-overview.
                                                             (line  188)
* data type, DOUBLE PRECISION:           numeric-type-overview.
                                                             (line  205)
* data type, ENUM <1>:                   enum.               (line    6)
* data type, ENUM:                       string-type-overview.
                                                             (line  220)
* data type, FIXED:                      numeric-type-overview.
                                                             (line  241)
* data type, FLOAT:                      numeric-type-overview.
                                                             (line  168)
* data type, GEOMETRY:                   mysql-spatial-datatypes.
                                                             (line    6)
* data type, GEOMETRYCOLLECTION:         mysql-spatial-datatypes.
                                                             (line    6)
* data type, INT:                        numeric-type-overview.
                                                             (line  118)
* data type, INTEGER:                    numeric-type-overview.
                                                             (line  123)
* data type, LINESTRING:                 mysql-spatial-datatypes.
                                                             (line    6)
* data type, LONG:                       blob.               (line    6)
* data type, LONGBLOB:                   string-type-overview.
                                                             (line  201)
* data type, LONGTEXT:                   string-type-overview.
                                                             (line  210)
* data type, MEDIUMBLOB:                 string-type-overview.
                                                             (line  187)
* data type, MEDIUMINT:                  numeric-type-overview.
                                                             (line  113)
* data type, MEDIUMTEXT:                 string-type-overview.
                                                             (line  193)
* data type, MULTILINESTRING:            mysql-spatial-datatypes.
                                                             (line    6)
* data type, MULTIPOINT:                 mysql-spatial-datatypes.
                                                             (line    6)
* data type, MULTIPOLYGON:               mysql-spatial-datatypes.
                                                             (line    6)
* data type, NATIONAL CHAR:              string-type-overview.
                                                             (line   80)
* data type, NATIONAL VARCHAR:           string-type-overview.
                                                             (line  110)
* data type, NCHAR:                      string-type-overview.
                                                             (line   80)
* data type, NUMERIC:                    numeric-type-overview.
                                                             (line  241)
* data type, NVARCHAR:                   string-type-overview.
                                                             (line  110)
* data type, POINT:                      mysql-spatial-datatypes.
                                                             (line    6)
* data type, POLYGON:                    mysql-spatial-datatypes.
                                                             (line    6)
* data type, REAL:                       numeric-type-overview.
                                                             (line  205)
* data type, SET <1>:                    set.                (line    6)
* data type, SET:                        string-type-overview.
                                                             (line  229)
* data type, SMALLINT:                   numeric-type-overview.
                                                             (line  108)
* data type, TEXT <1>:                   blob.               (line    6)
* data type, TEXT:                       string-type-overview.
                                                             (line  175)
* data type, TIME <1>:                   time.               (line    6)
* data type, TIME:                       date-and-time-type-overview.
                                                             (line   58)
* data type, TIMESTAMP <1>:              datetime.           (line   10)
* data type, TIMESTAMP:                  date-and-time-type-overview.
                                                             (line   28)
* data type, TINYBLOB:                   string-type-overview.
                                                             (line  151)
* data type, TINYINT:                    numeric-type-overview.
                                                             (line   40)
* data type, TINYTEXT:                   string-type-overview.
                                                             (line  157)
* data type, VARBINARY <1>:              binary-varbinary.   (line    6)
* data type, VARBINARY:                  string-type-overview.
                                                             (line  145)
* data type, VARCHAR <1>:                string-types.       (line   14)
* data type, VARCHAR:                    string-type-overview.
                                                             (line  110)
* data type, VARCHARACTER:               string-type-overview.
                                                             (line  110)
* data type, YEAR <1>:                   year.               (line    6)
* data type, YEAR:                       date-and-time-type-overview.
                                                             (line   65)
* data types:                            data-types.         (line   29)
* data types, C API:                     c.                  (line   25)
* data types, overview:                  data-type-overview. (line   13)
* data, character sets:                  charset-configuration.
                                                             (line   10)
* data, importing:                       batch-commands.     (line    6)
* data, loading into tables:             loading-tables.     (line    6)
* data, retrieving:                      retrieving-data.    (line   18)
* data, size:                            data-size.          (line    6)
* data-file-length option, myisamchk:    myisamchk-repair-options.
                                                             (line   21)
* database design:                       design.             (line    6)
* Database information, obtaining:       show.               (line   46)
* database metadata:                     information-schema. (line   36)
* database names, case sensitivity:      identifier-case-sensitivity.
                                                             (line    6)
* database names, case-sensitivity:      extensions-to-ansi. (line   38)
* database option, mysql:                mysql-command-options.
                                                             (line  181)
* database option, mysqlbinlog:          mysqlbinlog.        (line  127)
* DATABASE():                            information-functions.
                                                             (line  158)
* database, altering:                    alter-database.     (line    6)
* database, creating:                    create-database.    (line    6)
* database, deleting:                    drop-database.      (line    6)
* databases option, mysqlcheck:          mysqlcheck.         (line  211)
* databases option, mysqldump:           mysqldump.          (line  355)
* databases, backups:                    backup-and-recovery.
                                                             (line   13)
* databases, copying:                    upgrading-to-arch.  (line    6)
* databases, creating:                   database-use.       (line   13)
* databases, defined:                    what-is-mysql.      (line   28)
* databases, information about:          getting-information.
                                                             (line    6)
* databases, names:                      identifiers.        (line   13)
* databases, replicating:                replication.        (line   13)
* databases, selecting:                  creating-database.  (line    6)
* databases, symbolic links:             symbolic-links-to-databases.
                                                             (line    6)
* databases, using:                      database-use.       (line   13)
* DataDir <1>:                           mysql-cluster-ndbd-definition.
                                                             (line  112)
* DataDir:                               mysql-cluster-mgm-definition.
                                                             (line  118)
* datadir option, mysql.server:          mysql-server.       (line   38)
* datadir option, mysql_upgrade:         mysql-upgrade.      (line   77)
* datadir option, mysqld:                server-options.     (line  298)
* datadir option, mysqld_safe:           mysqld-safe.        (line  131)
* DataJunction:                          myodbc-usagenotes-apptips-datajunction.
                                                             (line    6)
* DataMemory <1>:                        mysql-cluster-config-lcp-params.
                                                             (line    6)
* DataMemory:                            mysql-cluster-ndbd-definition.
                                                             (line  149)
* DATE:                                  using-date.         (line    6)
* date and time functions:               date-and-time-functions.
                                                             (line    6)
* Date and Time types:                   date-and-time-types.
                                                             (line   13)
* date calculations:                     date-calculations.  (line    6)
* DATE columns, problems:                using-date.         (line    6)
* DATE data type <1>:                    datetime.           (line   10)
* DATE data type:                        date-and-time-type-overview.
                                                             (line   14)
* date functions, Y2K compliance:        y2k-issues.         (line    6)
* date types:                            storage-requirements.
                                                             (line   72)
* date types, Y2K issues:                y2k-issues.         (line    6)
* date values, problems:                 datetime.           (line  157)
* DATE():                                date-and-time-functions.
                                                             (line  222)
* DATE_ADD():                            date-and-time-functions.
                                                             (line  241)
* DATE_FORMAT():                         date-and-time-functions.
                                                             (line  395)
* DATE_SUB():                            date-and-time-functions.
                                                             (line  241)
* DATEDIFF():                            date-and-time-functions.
                                                             (line  229)
* dates, used with partitioning:         partitioning-types. (line   39)
* dates, used with partitioning (examples) <1>: partitioning-pruning.
                                                             (line   72)
* dates, used with partitioning (examples) <2>: partitioning-subpartitions.
                                                             (line   30)
* dates, used with partitioning (examples) <3>: partitioning-hash.
                                                             (line   49)
* dates, used with partitioning (examples): partitioning-range.
                                                             (line  125)
* DATETIME data type <1>:                datetime.           (line   10)
* DATETIME data type:                    date-and-time-type-overview.
                                                             (line   21)
* DAY():                                 date-and-time-functions.
                                                             (line  480)
* DAYNAME():                             date-and-time-functions.
                                                             (line  484)
* DAYOFMONTH():                          date-and-time-functions.
                                                             (line  493)
* DAYOFWEEK():                           date-and-time-functions.
                                                             (line  502)
* DAYOFYEAR():                           date-and-time-functions.
                                                             (line  511)
* db option, mysqlaccess:                mysqlaccess.        (line   78)
* db table, sorting:                     request-access.     (line   49)
* DB2 SQL mode:                          server-sql-mode.    (line  456)
* DBI interface:                         perl.               (line    6)
* DBI->quote:                            string-syntax.      (line  133)
* DBI->trace:                            using-gdb-on-mysqld.
                                                             (line   86)
* DBI/DBD interface:                     perl.               (line    6)
* DBI_TRACE environment variable <1>:    using-gdb-on-mysqld.
                                                             (line   86)
* DBI_TRACE environment variable:        environment-variables.
                                                             (line   18)
* DBI_USER environment variable:         environment-variables.
                                                             (line   18)
* DBUG package:                          the-dbug-package.   (line    6)
* DEALLOCATE PREPARE:                    sql-syntax-prepared-statements.
                                                             (line   10)
* debug option, comp_err:                comp-err.           (line   33)
* debug option, make_win_bin_dist:       make-win-bin-dist.  (line   36)
* debug option, my_print_defaults:       my-print-defaults.  (line   33)
* debug option, myisamchk:               myisamchk-general-options.
                                                             (line   15)
* debug option, myisampack:              myisampack.         (line   58)
* debug option, mysql:                   mysql-command-options.
                                                             (line  185)
* debug option, mysqlaccess:             mysqlaccess.        (line   82)
* debug option, mysqladmin:              mysqladmin.         (line  313)
* debug option, mysqlbinlog:             mysqlbinlog.        (line  138)
* debug option, mysqlcheck:              mysqlcheck.         (line  218)
* debug option, mysqld:                  server-options.     (line  310)
* debug option, mysqldump:               mysqldump.          (line  363)
* debug option, mysqlhotcopy:            mysqlhotcopy.       (line   93)
* debug option, mysqlimport:             mysqlimport.        (line  126)
* debug option, mysqlmanager:            instance-manager-command-options.
                                                             (line   60)
* debug option, mysqlshow:               mysqlshow.          (line  116)
* debug option, mysqlslap:               mysqlslap.          (line  226)
* Debug, thread command:                 thread-commands.    (line   38)
* debug-check option, mysql:             mysql-command-options.
                                                             (line  190)
* debug-check option, mysql_upgrade:     mysql-upgrade.      (line   81)
* debug-check option, mysqladmin:        mysqladmin.         (line   28)
* debug-check option, mysqlbinlog:       mysqlbinlog.        (line  143)
* debug-check option, mysqlcheck:        mysqlcheck.         (line  223)
* debug-check option, mysqldump:         mysqldump.          (line  369)
* debug-check option, mysqlimport:       mysqlimport.        (line  131)
* debug-check option, mysqlshow:         mysqlshow.          (line  121)
* debug-check option, mysqlslap:         mysqlslap.          (line  231)
* debug-info option, comp_err:           comp-err.           (line   38)
* debug-info option, mysql:              mysql-command-options.
                                                             (line  195)
* debug-info option, mysql_upgrade:      mysql-upgrade.      (line   86)
* debug-info option, mysqladmin:         mysqladmin.         (line   33)
* debug-info option, mysqlbinlog:        mysqlbinlog.        (line  148)
* debug-info option, mysqlcheck:         mysqlcheck.         (line  228)
* debug-info option, mysqldump:          mysqldump.          (line  374)
* debug-info option, mysqlimport:        mysqlimport.        (line  136)
* debug-info option, mysqlshow:          mysqlshow.          (line  126)
* debug-info option, mysqlslap:          mysqlslap.          (line  236)
* debugging support:                     configure-options.  (line    6)
* debugging, client:                     debugging-client.   (line    6)
* debugging, server:                     debugging-server.   (line   16)
* DEC data type:                         numeric-type-overview.
                                                             (line  241)
* decimal arithmetic:                    precision-math.     (line   14)
* DECIMAL data type <1>:                 precision-math.     (line   14)
* DECIMAL data type:                     numeric-type-overview.
                                                             (line  225)
* decimal point:                         data-types.         (line   36)
* DECLARE:                               declare.            (line    6)
* DECODE():                              encryption-functions.
                                                             (line  112)
* decode_bits myisamchk variable:        myisamchk-general-options.
                                                             (line   45)
* default hostname:                      connecting.         (line    6)
* default installation location:         installation-layouts.
                                                             (line    6)
* default options:                       option-files.       (line   11)
* DEFAULT value clause <1>:              create-table.       (line  295)
* DEFAULT value clause:                  data-type-defaults. (line    6)
* default values <1>:                    insert.             (line   66)
* default values <2>:                    create-table.       (line  295)
* default values <3>:                    data-type-defaults. (line    6)
* default values:                        design-limitations. (line   19)
* default values, BLOB and TEXT columns: blob.               (line   49)
* default values, explicit:              data-type-defaults. (line    6)
* default values, implicit:              data-type-defaults. (line    6)
* default values, suppression:           constraint-invalid-data.
                                                             (line    6)
* DEFAULT():                             miscellaneous-functions.
                                                             (line   27)
* DEFAULT, constraint:                   constraint-invalid-data.
                                                             (line    6)
* default, privileges:                   default-privileges. (line    6)
* default-character-set option, mysql:   mysql-command-options.
                                                             (line  203)
* default-character-set option, mysqladmin: mysqladmin.      (line  319)
* default-character-set option, mysqlcheck: mysqlcheck.      (line  233)
* default-character-set option, mysqld:  server-options.     (line  336)
* default-character-set option, mysqldump: mysqldump.        (line  379)
* default-character-set option, mysqlimport: mysqlimport.    (line  141)
* default-character-set option, mysqlshow: mysqlshow.        (line  131)
* default-collation option, mysqld:      server-options.     (line  346)
* default-mysqld-path option, mysqlmanager: instance-manager-command-options.
                                                             (line   65)
* default-storage-engine option, mysqld: server-options.     (line  359)
* default-table-type option, mysqld:     server-options.     (line  364)
* default-time-zone option, mysqld:      server-options.     (line  372)
* defaults, embedded:                    libmysqld-options.  (line    6)
* defaults-extra-file option:            option-file-options.
                                                             (line   30)
* defaults-extra-file option, my_print_defaults: my-print-defaults.
                                                             (line   39)
* defaults-extra-file option, mysqld_multi: mysqld-multi.    (line   65)
* defaults-extra-file option, mysqld_safe: mysqld-safe.      (line  135)
* defaults-file option:                  option-file-options.
                                                             (line   24)
* defaults-file option, my_print_defaults: my-print-defaults.
                                                             (line   29)
* defaults-file option, mysqld_multi:    mysqld-multi.       (line   63)
* defaults-file option, mysqld_safe:     mysqld-safe.        (line  142)
* defaults-file option, mysqlmanager:    instance-manager-command-options.
                                                             (line   74)
* defaults-group-suffix option:          option-file-options.
                                                             (line   37)
* defaults-group-suffix option, my_print_defaults: my-print-defaults.
                                                             (line   46)
* DEGREES():                             mathematical-functions.
                                                             (line  185)
* delay-key-write option, mysqld <1>:    myisam-start.       (line   35)
* delay-key-write option, mysqld:        server-options.     (line  382)
* DELAYED:                               insert-delayed.     (line    6)
* Delayed insert, thread command:        thread-commands.    (line   42)
* delayed inserts, thread states:        delayed-insert-thread-states.
                                                             (line    6)
* DELAYED, when ignored:                 insert.             (line  217)
* delayed-insert option, mysqldump:      mysqldump.          (line  388)
* delayed_insert_limit:                  insert-delayed.     (line  101)
* DELETE:                                delete.             (line    6)
* delete option, mysqlimport:            mysqlimport.        (line  146)
* DELETE, and MySQL Cluster:             mysql-cluster-limitations-limits.
                                                             (line    9)
* delete-master-logs option, mysqldump:  mysqldump.          (line  392)
* deleting from main table, thread state: general-thread-states.
                                                             (line   88)
* deleting from reference tables, thread state: general-thread-states.
                                                             (line   94)
* deleting, database:                    drop-database.      (line    6)
* deleting, foreign key <1>:             innodb-foreign-key-constraints.
                                                             (line  244)
* deleting, foreign key:                 alter-table.        (line  513)
* deleting, function:                    drop-function-udf.  (line    6)
* deleting, index <1>:                   drop-index.         (line    6)
* deleting, index:                       alter-table.        (line  402)
* deleting, primary key:                 alter-table.        (line  414)
* deleting, rows:                        deleting-from-related-tables.
                                                             (line    6)
* deleting, schema:                      drop-database.      (line    6)
* deleting, table:                       drop-table.         (line    6)
* deleting, user <1>:                    drop-user.          (line    6)
* deleting, user:                        removing-users.     (line    6)
* deleting, users <1>:                   drop-user.          (line    6)
* deleting, users:                       removing-users.     (line    6)
* deletion, mysql.sock:                  problems-with-mysql-sock.
                                                             (line    6)
* delimiter command, mysql:              mysql-commands.     (line   82)
* delimiter option, mysql:               mysql-command-options.
                                                             (line  208)
* delimiter option, mysqlslap:           mysqlslap.          (line  241)
* delimiter option, ndb_select_all:      mysql-cluster-utilities-ndb-select-all.
                                                             (line   48)
* Delphi:                                myodbc-usagenotes-apptips-borland-delphi.
                                                             (line    6)
* derived tables:                        unnamed-views.      (line    6)
* des-key-file option, mysqld:           server-options.     (line  408)
* DES_DECRYPT():                         encryption-functions.
                                                             (line  127)
* DES_ENCRYPT():                         encryption-functions.
                                                             (line  148)
* DESC:                                  describe.           (line    6)
* descending option, ndb_select_all:     mysql-cluster-utilities-ndb-select-all.
                                                             (line   33)
* DESCRIBE <1>:                          describe.           (line    6)
* DESCRIBE:                              getting-information.
                                                             (line    6)
* description option, myisamchk:         myisamchk-other-options.
                                                             (line   28)
* design, choices:                       design.             (line    6)
* design, issues:                        bugs.               (line   11)
* design, limitations:                   design-limitations. (line    6)
* detach option, mysqlslap:              mysqlslap.          (line  246)
* developers, list of:                   credits.            (line   16)
* development source tree:               installing-source-tree.
                                                             (line    6)
* Difference():                          spatial-operators.  (line   22)
* digits:                                data-types.         (line   36)
* Dimension():                           general-geometry-property-functions.
                                                             (line    9)
* directory structure, default:          installation-layouts.
                                                             (line    6)
* disable named command, mysql:          mysql-command-options.
                                                             (line  213)
* disable-grant-options option, configure: configure-options.
                                                             (line  501)
* disable-keys option, mysqldump:        mysqldump.          (line  398)
* disable-log-bin option, mysqlbinlog:   mysqlbinlog.        (line  153)
* DISCARD TABLESPACE <1>:                multiple-tablespaces.
                                                             (line   60)
* DISCARD TABLESPACE:                    alter-table.        (line  523)
* discard_or_import_tablespace, thread state: general-thread-states.
                                                             (line   99)
* disconnect-slave-event-count option, mysqld: server-options.
                                                             (line  413)
* disconnecting, from the server:        connecting-disconnecting.
                                                             (line    6)
* Disjoint():                            functions-that-test-spatial-relationships-between-geometries.
                                                             (line   44)
* Disk Data tables (MySQL Cluster):      mysql-cluster-disk-data.
                                                             (line   12)
* disk full:                             full-disk.          (line    6)
* disk issues:                           disk-issues.        (line   10)
* disk option, ndb_select_all:           mysql-cluster-utilities-ndb-select-all.
                                                             (line   55)
* DiskCheckpointSpeed:                   mysql-cluster-ndbd-definition.
                                                             (line 1163)
* DiskCheckpointSpeedInRestart:          mysql-cluster-ndbd-definition.
                                                             (line 1172)
* Diskless:                              mysql-cluster-ndbd-definition.
                                                             (line  826)
* DiskPageBufferMemory:                  mysql-cluster-disk-data-parameters.
                                                             (line    9)
* disks, splitting data across:          windows-symbolic-links.
                                                             (line    6)
* DiskSyncSize:                          mysql-cluster-ndbd-definition.
                                                             (line 1146)
* display size:                          data-types.         (line   31)
* display triggers:                      show-triggers.      (line    6)
* display width:                         data-types.         (line   31)
* displaying, information, Cardinality:  show-index.         (line   38)
* displaying, information, Collation:    show-index.         (line   33)
* displaying, information, SHOW <1>:     show-tables.        (line    6)
* displaying, information, SHOW <2>:     show-open-tables.   (line    6)
* displaying, information, SHOW <3>:     show-index.         (line    6)
* displaying, information, SHOW <4>:     show-columns.       (line    6)
* displaying, information, SHOW:         show.               (line   46)
* displaying, table status:              show-table-status.  (line    6)
* Distance():                            functions-that-test-spatial-relationships-between-geometries.
                                                             (line   49)
* DISTINCT <1>:                          select.             (line  403)
* DISTINCT <2>:                          distinct-optimization.
                                                             (line    6)
* DISTINCT:                              selecting-columns.  (line   43)
* DISTINCT, AVG():                       group-by-functions. (line   52)
* DISTINCT, COUNT():                     group-by-functions. (line  116)
* DISTINCT, MAX():                       group-by-functions. (line  180)
* DISTINCT, MIN():                       group-by-functions. (line  199)
* DISTINCT, SUM():                       group-by-functions. (line  249)
* DISTINCTROW:                           select.             (line  403)
* DIV:                                   arithmetic-functions.
                                                             (line  100)
* division (/):                          arithmetic-functions.
                                                             (line   85)
* DNS:                                   dns.                (line    6)
* DO:                                    do.                 (line    6)
* DocBook XML, documentation source format: manual-info.     (line   28)
* Documentation, in Chinese:             faqs-cjk.           (line   89)
* Documentation, in Japanese:            faqs-cjk.           (line   89)
* Documentation, in Korean:              faqs-cjk.           (line   89)
* Documenters, list of:                  documenters-translators.
                                                             (line    6)
* DOUBLE data type:                      numeric-type-overview.
                                                             (line  188)
* DOUBLE PRECISION data type:            numeric-type-overview.
                                                             (line  205)
* double quote (\"):                     string-syntax.      (line   50)
* downgrades, MySQL Cluster <1>:         mysql-cluster-upgrade-downgrade-compatibility.
                                                             (line    6)
* downgrades, MySQL Cluster <2>:         mysql-cluster-rolling-restart.
                                                             (line    6)
* downgrades, MySQL Cluster:             mysql-cluster-upgrade-downgrade.
                                                             (line   11)
* downgrading:                           downgrading.        (line   10)
* downloading:                           getting-mysql.      (line    6)
* DRBD:                                  faqs-drbd.          (line   10)
* DRBD licence:                          faqs-drbd.          (line   16)
* drbd, FAQ:                             faqs-mysql-drbd-heartbeat.
                                                             (line   19)
* DROP DATABASE:                         drop-database.      (line    6)
* Drop DB, thread command:               thread-commands.    (line   46)
* DROP EVENT:                            drop-event.         (line    6)
* DROP FOREIGN KEY <1>:                  innodb-foreign-key-constraints.
                                                             (line  244)
* DROP FOREIGN KEY:                      alter-table.        (line  513)
* DROP FUNCTION <1>:                     drop-procedure.     (line    6)
* DROP FUNCTION:                         drop-function-udf.  (line    6)
* DROP INDEX <1>:                        drop-index.         (line    6)
* DROP INDEX:                            alter-table.        (line  402)
* DROP LOGFILE GROUP:                    drop-logfile-group. (line    6)
* DROP PREPARE:                          sql-syntax-prepared-statements.
                                                             (line   94)
* DROP PRIMARY KEY:                      alter-table.        (line  414)
* DROP PROCEDURE:                        drop-procedure.     (line    6)
* DROP SCHEMA:                           drop-database.      (line    6)
* DROP SERVER:                           drop-server.        (line    6)
* DROP TABLE:                            drop-table.         (line    6)
* DROP TABLE, and MySQL Cluster:         mysql-cluster-limitations-limits.
                                                             (line    9)
* DROP TABLESPACE:                       drop-tablespace.    (line    6)
* DROP TRIGGER:                          drop-trigger.       (line    6)
* DROP USER:                             drop-user.          (line    6)
* DROP VIEW:                             drop-view.          (line    6)
* drop-user option, mysqlmanager:        instance-manager-command-options.
                                                             (line   86)
* dropping, user <1>:                    drop-user.          (line    6)
* dropping, user:                        removing-users.     (line    6)
* dryrun option, mysqlhotcopy:           mysqlhotcopy.       (line   97)
* DUAL:                                  select.             (line   63)
* dump option, myisam_ftdump:            myisam-ftdump.      (line   55)
* dump-date option, mysqldump:           mysqldump.          (line  407)
* DUMPFILE:                              select.             (line  364)
* dynamic table characteristics:         dynamic-format.     (line    6)
* edit command, mysql:                   mysql-commands.     (line  100)
* edit-user option, mysqlmanager:        instance-manager-command-options.
                                                             (line   91)
* ego command, mysql:                    mysql-commands.     (line  109)
* Eiffel Wrapper:                        eiffel.             (line    6)
* ELT():                                 string-functions.   (line  223)
* email lists:                           mailing-lists.      (line   10)
* embedded MySQL server library:         libmysqld.          (line   14)
* embedded option, make_win_bin_dist:    make-win-bin-dist.  (line   41)
* enable-named-pipe option, mysqld:      server-options.     (line  421)
* enable-pstack option, mysqld:          server-options.     (line  433)
* enable-thread-safe-client option, configure: configure-options.
                                                             (line  476)
* ENCODE():                              encryption-functions.
                                                             (line  117)
* ENCRYPT():                             encryption-functions.
                                                             (line  199)
* encryption:                            secure-basics.      (line   18)
* encryption functions:                  encryption-functions.
                                                             (line    6)
* END:                                   begin-end.          (line    6)
* end, thread state:                     general-thread-states.
                                                             (line  104)
* EndPoint():                            linestring-property-functions.
                                                             (line   10)
* engine option, mysqlslap:              mysqlslap.          (line  252)
* ENGINES, INFORMATION_SCHEMA table:     engines-table.      (line    6)
* ENTER SINGLE USER MODE command (MySQL Cluster): mysql-cluster-mgm-client-commands.
                                                             (line   99)
* entering, queries:                     entering-queries.   (line    6)
* ENUM data type <1>:                    enum.               (line    6)
* ENUM data type:                        string-type-overview.
                                                             (line  220)
* ENUM, size:                            storage-requirements.
                                                             (line  193)
* Envelope():                            general-geometry-property-functions.
                                                             (line   22)
* Environment variable, CC:              environment-variables.
                                                             (line   18)
* environment variable, CC <1>:          compilation-problems.
                                                             (line  108)
* environment variable, CC:              configure-options.  (line  349)
* Environment variable, CFLAGS:          environment-variables.
                                                             (line   18)
* environment variable, CFLAGS <1>:      compilation-problems.
                                                             (line  108)
* environment variable, CFLAGS:          configure-options.  (line  363)
* Environment variable, CXX:             environment-variables.
                                                             (line   18)
* environment variable, CXX:             compilation-problems.
                                                             (line  108)
* Environment variable, CXX:             compilation-problems.
                                                             (line   66)
* environment variable, CXX:             configure-options.  (line  349)
* Environment variable, CXXFLAGS:        environment-variables.
                                                             (line   18)
* environment variable, CXXFLAGS <1>:    compilation-problems.
                                                             (line  108)
* environment variable, CXXFLAGS:        configure-options.  (line  363)
* Environment variable, DBI_TRACE <1>:   using-gdb-on-mysqld.
                                                             (line   86)
* Environment variable, DBI_TRACE:       environment-variables.
                                                             (line   18)
* Environment variable, DBI_USER:        environment-variables.
                                                             (line   18)
* environment variable, HOME:            mysql-command-options.
                                                             (line  566)
* Environment variable, HOME:            environment-variables.
                                                             (line   18)
* Environment variable, LD_LIBRARY_PATH: perl-support-problems.
                                                             (line   23)
* Environment variable, LD_RUN_PATH <1>: perl-support-problems.
                                                             (line   23)
* Environment variable, LD_RUN_PATH:     environment-variables.
                                                             (line   18)
* environment variable, LD_RUN_PATH <1>: solaris.            (line  151)
* environment variable, LD_RUN_PATH:     source-notes-linux. (line   97)
* Environment variable, MYSQL_DEBUG:     debugging-client.   (line   10)
* environment variable, MYSQL_DEBUG:     programs-overview.  (line  303)
* Environment variable, MYSQL_DEBUG:     environment-variables.
                                                             (line   18)
* Environment variable, MYSQL_GROUP_SUFFIX: environment-variables.
                                                             (line   18)
* environment variable, MYSQL_HISTFILE:  mysql-command-options.
                                                             (line  566)
* Environment variable, MYSQL_HISTFILE:  environment-variables.
                                                             (line   18)
* Environment variable, MYSQL_HOME:      environment-variables.
                                                             (line   18)
* environment variable, MYSQL_HOST:      connecting.         (line  209)
* Environment variable, MYSQL_HOST:      environment-variables.
                                                             (line   18)
* Environment variable, MYSQL_PS1:       environment-variables.
                                                             (line   18)
* environment variable, MYSQL_PWD <1>:   connecting.         (line  209)
* environment variable, MYSQL_PWD:       programs-overview.  (line  303)
* Environment variable, MYSQL_PWD:       environment-variables.
                                                             (line   18)
* environment variable, MYSQL_TCP_PORT <1>: multiple-server-clients.
                                                             (line   27)
* environment variable, MYSQL_TCP_PORT <2>: multiple-unix-servers.
                                                             (line   58)
* environment variable, MYSQL_TCP_PORT:  programs-overview.  (line  303)
* Environment variable, MYSQL_TCP_PORT:  environment-variables.
                                                             (line   18)
* environment variable, MYSQL_UNIX_PORT <1>: multiple-server-clients.
                                                             (line   27)
* environment variable, MYSQL_UNIX_PORT <2>: multiple-unix-servers.
                                                             (line   58)
* environment variable, MYSQL_UNIX_PORT: programs-overview.  (line  303)
* Environment variable, MYSQL_UNIX_PORT <1>: environment-variables.
                                                             (line   18)
* Environment variable, MYSQL_UNIX_PORT: mysql-install-db-problems.
                                                             (line   76)
* environment variable, PATH:            invoking-programs.  (line   48)
* Environment variable, PATH:            environment-variables.
                                                             (line   18)
* environment variable, PATH:            installing-binary.  (line  115)
* Environment variable, TMPDIR <1>:      environment-variables.
                                                             (line   18)
* Environment variable, TMPDIR:          mysql-install-db-problems.
                                                             (line   76)
* Environment variable, TZ <1>:          timezone-problems.  (line    6)
* Environment variable, TZ:              environment-variables.
                                                             (line   18)
* Environment variable, UMASK <1>:       file-permissions.   (line    6)
* Environment variable, UMASK:           environment-variables.
                                                             (line   18)
* Environment variable, UMASK_DIR <1>:   file-permissions.   (line   19)
* Environment variable, UMASK_DIR:       environment-variables.
                                                             (line   18)
* environment variable, USER:            connecting.         (line  209)
* Environment variable, USER:            environment-variables.
                                                             (line   18)
* environment variables <1>:             access-denied.      (line  101)
* environment variables <2>:             setting-environment-variables.
                                                             (line    6)
* environment variables:                 programs-overview.  (line  300)
* Environment variables, CXX:            compilation-problems.
                                                             (line   76)
* environment variables, list of:        environment-variables.
                                                             (line    6)
* eq_ref join type, optimizer:           using-explain.      (line  143)
* equal (=):                             comparison-operators.
                                                             (line   55)
* Equals():                              functions-that-test-spatial-relationships-between-geometries.
                                                             (line   54)
* ERROR Events (MySQL Cluster):          mysql-cluster-log-events.
                                                             (line  194)
* error logs (MySQL Cluster):            mysql-cluster-ndbd-process.
                                                             (line   24)
* error messages, can't find file:       file-permissions.   (line    6)
* error messages, languages:             error-message-language.
                                                             (line    6)
* Error, thread command:                 thread-commands.    (line   50)
* ERROR_FOR_DIVISION_BY_ZERO SQL mode:   server-sql-mode.    (line  111)
* errors, access denied:                 error-access-denied.
                                                             (line    6)
* errors, checking tables for:           check.              (line    6)
* errors, common:                        problems.           (line   17)
* errors, directory checksum:            solaris.            (line   11)
* errors, handling for UDFs:             udf-return-values.  (line    6)
* errors, in subqueries:                 subquery-errors.    (line    6)
* errors, known:                         bugs.               (line   11)
* errors, linking:                       link-errors.        (line    6)
* errors, list of:                       common-errors.      (line   28)
* errors, lost connection:               error-lost-connection.
                                                             (line    6)
* errors, reporting <1>:                 bug-reports.        (line    6)
* errors, reporting:                     introduction.       (line   77)
* escape (\\):                           string-syntax.      (line   56)
* escape characters:                     literals.           (line   15)
* estimating, query performance:         estimating-performance.
                                                             (line    6)
* event log format (MySQL Cluster):      mysql-cluster-log-events.
                                                             (line    6)
* event logs (MySQL Cluster) <1>:        mysql-cluster-logging-management-commands.
                                                             (line    6)
* event logs (MySQL Cluster):            mysql-cluster-event-reports.
                                                             (line   12)
* event restrictions:                    routine-restrictions.
                                                             (line    6)
* Event Scheduler:                       events.             (line   15)
* Event Scheduler, altering events:      alter-event.        (line    6)
* Event Scheduler, and MySQL privileges: events-privileges.  (line    6)
* Event Scheduler, and mysqladmin debug: events-status-info. (line    6)
* Event Scheduler, and SHOW PROCESSLIST: events-overview.    (line   98)
* Event Scheduler, concepts:             events-overview.    (line    6)
* Event Scheduler, creating events:      create-event.       (line    6)
* Event Scheduler, dropping events:      drop-event.         (line    6)
* Event Scheduler, enabling and disabling: events-overview.  (line   81)
* Event Scheduler, event metadata:       events-metadata.    (line    6)
* Event Scheduler, obtaining status information <1>: events-status-info.
                                                             (line    6)
* Event Scheduler, obtaining status information: show-scheduler-status.
                                                             (line    6)
* Event Scheduler, SQL statements:       events-syntax.      (line   12)
* Event Scheduler, starting and stopping: events-overview.   (line   81)
* event scheduler, thread states:        event-scheduler-thread-states.
                                                             (line    6)
* event severity levels (MySQL Cluster): mysql-cluster-logging-management-commands.
                                                             (line   55)
* event types (MySQL Cluster) <1>:       mysql-cluster-log-events.
                                                             (line   20)
* event types (MySQL Cluster):           mysql-cluster-event-reports.
                                                             (line   49)
* event-scheduler option, mysqld:        server-options.     (line  477)
* events:                                events.             (line   15)
* events option, mysqldump:              mysqldump.          (line  418)
* events, altering:                      alter-event.        (line    6)
* events, creating:                      create-event.       (line    6)
* events, dropping:                      drop-event.         (line    6)
* EVENTS, INFORMATION_SCHEMA table <1>:  events-table.       (line    6)
* EVENTS, INFORMATION_SCHEMA table:      events-privileges.  (line   71)
* events, limitations:                   events-limitations-restrictions.
                                                             (line    6)
* events, metadata:                      events-metadata.    (line    6)
* events, status variables:              events-privileges.  (line  182)
* exact-value literals:                  precision-math.     (line   14)
* example option, mysqld_multi:          mysqld-multi.       (line   97)
* EXAMPLE storage engine <1>:            example-storage-engine.
                                                             (line    6)
* EXAMPLE storage engine:                storage-engines.    (line   21)
* examples, compressed tables:           myisampack.         (line  118)
* examples, myisamchk output:            table-info.         (line   37)
* examples, queries:                     examples.           (line   18)
* exe-suffix option, make_win_bin_dist:  make-win-bin-dist.  (line   46)
* EXECUTE:                               sql-syntax-prepared-statements.
                                                             (line   10)
* execute option, mysql:                 mysql-command-options.
                                                             (line  221)
* Execute, thread command:               thread-commands.    (line   52)
* ExecuteOnComputer <1>:                 mysql-cluster-api-definition.
                                                             (line   33)
* ExecuteOnComputer <2>:                 mysql-cluster-ndbd-definition.
                                                             (line   42)
* ExecuteOnComputer:                     mysql-cluster-mgm-definition.
                                                             (line   23)
* executing SQL statements from text files <1>: batch-commands.
                                                             (line    6)
* executing SQL statements from text files: batch-mode.      (line    6)
* Execution of init_command, thread state: general-thread-states.
                                                             (line  110)
* EXISTS, with subqueries:               exists-and-not-exists-subqueries.
                                                             (line    6)
* EXIT command (MySQL Cluster):          mysql-cluster-mgm-client-commands.
                                                             (line  115)
* exit command, mysql:                   mysql-commands.     (line  114)
* EXIT SINGLE USER MODE command (MySQL Cluster): mysql-cluster-mgm-client-commands.
                                                             (line  110)
* exit-info option, mysqld:              server-options.     (line  497)
* EXP():                                 mathematical-functions.
                                                             (line  194)
* EXPLAIN <1>:                           explain.            (line    6)
* EXPLAIN:                               using-explain.      (line    6)
* EXPLAIN PARTITIONS:                    partitioning-info.  (line    6)
* EXPLAIN used with partitioned tables:  partitioning-info.  (line    6)
* explicit default values:               data-type-defaults. (line    6)
* EXPORT_SET():                          string-functions.   (line  234)
* expression aliases <1>:                select.             (line   80)
* expression aliases:                    group-by-hidden-fields.
                                                             (line   51)
* expressions, extended:                 pattern-matching.   (line    6)
* extend-check option, myisamchk <1>:    myisamchk-repair-options.
                                                             (line   26)
* extend-check option, myisamchk:        myisamchk-check-options.
                                                             (line   18)
* extended option, mysqlcheck:           mysqlcheck.         (line  238)
* extended-insert option, mysqldump:     mysqldump.          (line  423)
* extensions, to standard SQL:           compatibility.      (line   15)
* ExteriorRing():                        polygon-property-functions.
                                                             (line   21)
* external locking <1>:                  general-thread-states.
                                                             (line  272)
* external locking <2>:                  external-locking.   (line    6)
* external locking <3>:                  crash-recovery.     (line    6)
* external locking <4>:                  server-system-variables.
                                                             (line 3471)
* external locking:                      server-options.     (line  506)
* external-locking option, mysqld:       server-options.     (line  506)
* extra-file option, my_print_defaults:  my-print-defaults.  (line   41)
* extra-partition-info option, ndb_desc: mysql-cluster-utilities-ndb-desc.
                                                             (line   66)
* EXTRACT():                             date-and-time-functions.
                                                             (line  518)
* extracting, dates:                     date-calculations.  (line    6)
* ExtractValue():                        xml-functions.      (line  150)
* failover, in MySQL Cluster replication: mysql-cluster-replication-failover.
                                                             (line    6)
* FALSE <1>:                             boolean-values.     (line    6)
* FALSE:                                 number-syntax.      (line    6)
* FALSE, testing for:                    comparison-operators.
                                                             (line  121)
* fast option, myisamchk:                myisamchk-check-options.
                                                             (line   29)
* fast option, mysqlcheck:               mysqlcheck.         (line  247)
* fatal signal 11:                       compilation-problems.
                                                             (line   38)
* features of MySQL:                     features.           (line    6)
* FEDERATED storage engine <1>:          federated-storage-engine.
                                                             (line   13)
* FEDERATED storage engine:              storage-engines.    (line   21)
* FETCH:                                 fetch.              (line    6)
* Fetch, thread command:                 thread-commands.    (line   56)
* Field List, thread command:            thread-commands.    (line   61)
* FIELD():                               string-functions.   (line  249)
* field, changing:                       alter-table.        (line  395)
* fields option, ndb_config:             mysql-cluster-utilities-ndb-config.
                                                             (line   92)
* fields-enclosed-by option, mysqldump <1>: mysqlimport.     (line  152)
* fields-enclosed-by option, mysqldump:  mysqldump.          (line  431)
* fields-escaped-by option, mysqldump <1>: mysqlimport.      (line  156)
* fields-escaped-by option, mysqldump:   mysqldump.          (line  435)
* fields-optionally-enclosed-by option, mysqldump <1>: mysqlimport.
                                                             (line  154)
* fields-optionally-enclosed-by option, mysqldump: mysqldump.
                                                             (line  433)
* fields-terminated-by option, mysqldump <1>: mysqlimport.   (line  150)
* fields-terminated-by option, mysqldump: mysqldump.         (line  429)
* FILE:                                  string-functions.   (line  368)
* files, binary log:                     binary-log.         (line   13)
* files, config.cache:                   compilation-problems.
                                                             (line    6)
* files, error messages:                 error-message-language.
                                                             (line    6)
* files, general query log:              query-log.          (line    6)
* FILES, INFORMATION_SCHEMA table:       files-table.        (line    6)
* files, log <1>:                        log-file-maintenance.
                                                             (line    6)
* files, log:                            configure-options.  (line    6)
* files, my.cnf:                         replication-features.
                                                             (line   33)
* files, not found message:              file-permissions.   (line    6)
* files, permissions:                    file-permissions.   (line    6)
* files, repairing:                      myisamchk-repair-options.
                                                             (line    6)
* files, script:                         batch-mode.         (line    6)
* files, size limits:                    full-table.         (line    6)
* files, slow query log:                 slow-query-log.     (line    6)
* files, text:                           batch-commands.     (line    6)
* files, tmp:                            mysql-install-db-problems.
                                                             (line   64)
* filesort optimization:                 order-by-optimization.
                                                             (line  102)
* FileSystemPath:                        mysql-cluster-ndbd-definition.
                                                             (line  117)
* FIND_IN_SET():                         string-functions.   (line  268)
* Finished reading one binlog; switching to next binlog, thread state: master-thread-states.
                                                             (line   17)
* firewalls (software), and MySQL Cluster: mysql-cluster-security-networking-issues.
                                                             (line   98)
* first-slave option, mysqldump:         mysqldump.          (line  441)
* fix-db-names option, mysqlcheck:       mysqlcheck.         (line  251)
* fix-table-names option, mysqlcheck:    mysqlcheck.         (line  257)
* FIXED data type:                       numeric-type-overview.
                                                             (line  241)
* fixed-point arithmetic:                precision-math.     (line   14)
* FLOAT data type:                       numeric-type-overview.
                                                             (line  168)
* floating-point number:                 numeric-type-overview.
                                                             (line  212)
* floats:                                number-syntax.      (line    6)
* FLOOR():                               mathematical-functions.
                                                             (line  207)
* FLUSH:                                 flush.              (line    6)
* flush option, mysqld:                  server-options.     (line  525)
* flush tables:                          mysqladmin.         (line  200)
* flush-logs option, mysqldump:          mysqldump.          (line  445)
* flush-privileges option, mysqldump:    mysqldump.          (line  457)
* Flushing tables, thread state:         general-thread-states.
                                                             (line  120)
* flushlog option, mysqlhotcopy:         mysqlhotcopy.       (line  101)
* FOR UPDATE:                            select.             (line  393)
* FORCE INDEX <1>:                       optimizer-issues.   (line   25)
* FORCE INDEX:                           index-hints.        (line    6)
* FORCE KEY:                             index-hints.        (line    6)
* force option, myisamchk <1>:           myisamchk-repair-options.
                                                             (line   32)
* force option, myisamchk:               myisamchk-check-options.
                                                             (line   33)
* force option, myisampack:              myisampack.         (line   63)
* force option, mysql:                   mysql-command-options.
                                                             (line  227)
* force option, mysql_upgrade:           mysql-upgrade.      (line   91)
* force option, mysqladmin:              mysqladmin.         (line  324)
* force option, mysqlcheck:              mysqlcheck.         (line  263)
* force option, mysqldump:               mysqldump.          (line  465)
* force option, mysqlimport:             mysqlimport.        (line  161)
* force-read option, mysqlbinlog:        mysqlbinlog.        (line  167)
* foreign key, constraint:               constraint-primary-key.
                                                             (line    6)
* foreign key, deleting <1>:             innodb-foreign-key-constraints.
                                                             (line  244)
* foreign key, deleting:                 alter-table.        (line  513)
* foreign keys <1>:                      alter-table.        (line  490)
* foreign keys <2>:                      example-foreign-keys.
                                                             (line    6)
* foreign keys:                          ansi-diff-foreign-keys.
                                                             (line    6)
* FORMAT():                              string-functions.   (line  283)
* Forums:                                forums.             (line    6)
* FOUND_ROWS():                          information-functions.
                                                             (line  172)
* FragmentLogFileSize:                   mysql-cluster-ndbd-definition.
                                                             (line  647)
* FreeBSD troubleshooting:               compilation-problems.
                                                             (line  104)
* freeing items, thread state:           general-thread-states.
                                                             (line  115)
* frequently-asked questions about DRBD: faqs-mysql-drbd-heartbeat.
                                                             (line   19)
* frequently-asked questions about MySQL Cluster: faqs-mysql-cluster.
                                                             (line    6)
* FROM:                                  select.             (line  107)
* FROM_DAYS():                           date-and-time-functions.
                                                             (line  534)
* FROM_UNIXTIME():                       date-and-time-functions.
                                                             (line  545)
* ft_max_word_len myisamchk variable:    myisamchk-general-options.
                                                             (line   45)
* ft_min_word_len myisamchk variable:    myisamchk-general-options.
                                                             (line   45)
* ft_stopword_file myisamchk variable:   myisamchk-general-options.
                                                             (line   45)
* full disk:                             full-disk.          (line    6)
* full-text search:                      fulltext-search.    (line   15)
* FULLTEXT:                              fulltext-search.    (line   15)
* FULLTEXT initialization, thread state: general-thread-states.
                                                             (line  125)
* fulltext join type, optimizer:         using-explain.      (line  187)
* fulltext, stopword list:               fulltext-fine-tuning.
                                                             (line   40)
* function names, parsing:               function-resolution.
                                                             (line    6)
* function names, resolving ambiguity:   function-resolution.
                                                             (line    6)
* function, creating:                    create-function-udf.
                                                             (line    6)
* function, deleting:                    drop-function-udf.  (line    6)
* functions:                             functions.          (line   21)
* functions for SELECT and WHERE clauses: functions.         (line   21)
* functions, arithmetic:                 bit-functions.      (line    6)
* functions, bit:                        bit-functions.      (line    6)
* functions, C API:                      c-api-function-overview.
                                                             (line    6)
* functions, C prepared statement API:   c-api-prepared-statement-function-overview.
                                                             (line    6)
* functions, cast:                       cast-functions.     (line    6)
* functions, control flow:               control-flow-functions.
                                                             (line    6)
* functions, date and time:              date-and-time-functions.
                                                             (line    6)
* functions, encryption:                 encryption-functions.
                                                             (line    6)
* functions, GROUP BY:                   group-by-functions. (line    6)
* functions, grouping:                   operator-precedence.
                                                             (line   37)
* functions, information:                information-functions.
                                                             (line    6)
* functions, mathematical:               mathematical-functions.
                                                             (line   52)
* functions, miscellaneous:              miscellaneous-functions.
                                                             (line    6)
* functions, native, adding:             adding-native-function.
                                                             (line    6)
* functions, new:                        adding-functions.   (line   12)
* functions, string:                     string-functions.   (line   11)
* functions, string comparison:          string-comparison-functions.
                                                             (line    6)
* functions, user-defined:               adding-functions.   (line   12)
* Functions, user-defined <1>:           drop-function-udf.  (line    6)
* Functions, user-defined:               create-function-udf.
                                                             (line    6)
* functions, user-defined, adding:       adding-udf.         (line   15)
* Future development of MySQL Cluster:   mysql-cluster-roadmap.
                                                             (line   13)
* gap lock <1>:                          innodb-next-key-locking.
                                                             (line    6)
* gap lock <2>:                          innodb-transaction-isolation.
                                                             (line   49)
* gap lock:                              innodb-parameters.  (line  429)
* gb2312, gbk:                           faqs-cjk.           (line   13)
* gcc:                                   configure-options.  (line  349)
* gci option, ndb_select_all:            mysql-cluster-utilities-ndb-select-all.
                                                             (line   65)
* gdb option, mysqld:                    server-options.     (line  539)
* gdb, using:                            using-gdb-on-mysqld.
                                                             (line    6)
* general information:                   introduction.       (line   17)
* General Public License:                what-is-mysql.      (line   42)
* general query log:                     query-log.          (line    6)
* general-log option, mysqld:            server-options.     (line  550)
* geographic feature:                    gis-introduction.   (line   27)
* GeomCollFromText():                    gis-wkt-functions.  (line   14)
* GeomCollFromWKB():                     gis-wkb-functions.  (line   15)
* geometry:                              gis-introduction.   (line   40)
* GEOMETRY data type:                    mysql-spatial-datatypes.
                                                             (line    6)
* GEOMETRYCOLLECTION data type:          mysql-spatial-datatypes.
                                                             (line    6)
* GeometryCollection():                  gis-mysql-specific-functions.
                                                             (line   14)
* GeometryCollectionFromText():          gis-wkt-functions.  (line   14)
* GeometryCollectionFromWKB():           gis-wkb-functions.  (line   15)
* GeometryFromText():                    gis-wkt-functions.  (line   20)
* GeometryFromWKB():                     gis-wkb-functions.  (line   21)
* GeometryN():                           geometrycollection-property-functions.
                                                             (line    8)
* GeometryType():                        general-geometry-property-functions.
                                                             (line   38)
* GeomFromText() <1>:                    functions-to-convert-geometries-between-formats.
                                                             (line   29)
* GeomFromText():                        gis-wkt-functions.  (line   20)
* GeomFromWKB() <1>:                     functions-to-convert-geometries-between-formats.
                                                             (line   36)
* GeomFromWKB():                         gis-wkb-functions.  (line   21)
* geospatial feature:                    gis-introduction.   (line   37)
* GET_FORMAT():                          date-and-time-functions.
                                                             (line  573)
* GET_LOCK():                            miscellaneous-functions.
                                                             (line   40)
* getting MySQL:                         getting-mysql.      (line    6)
* GIS <1>:                               gis-introduction.   (line    6)
* GIS:                                   spatial-extensions. (line   16)
* GLength() <1>:                         multilinestring-property-functions.
                                                             (line    8)
* GLength():                             linestring-property-functions.
                                                             (line   23)
* global privileges <1>:                 revoke.             (line    6)
* global privileges:                     grant.              (line    6)
* GLOBAL_STATUS, INFORMATION_SCHEMA table: status-table.     (line    6)
* GLOBAL_VARIABLES, INFORMATION_SCHEMA table: variables-table.
                                                             (line    6)
* go command, mysql:                     mysql-commands.     (line  118)
* goals of MySQL:                        what-is-mysql.      (line   87)
* got handler lock, thread state:        delayed-insert-thread-states.
                                                             (line   25)
* got old table, thread state:           delayed-insert-thread-states.
                                                             (line   31)
* GRANT:                                 grant.              (line    6)
* GRANT statement:                       adding-users.       (line    6)
* grant tables:                          request-access.     (line  166)
* grant tables, re-creating:             mysql-install-db-problems.
                                                             (line   95)
* grant tables, sorting <1>:             request-access.     (line   49)
* grant tables, sorting:                 connection-access.  (line  195)
* granting, privileges:                  grant.              (line    6)
* GRANTS:                                show-grants.        (line    6)
* greater than (>):                      comparison-operators.
                                                             (line  114)
* greater than or equal (>=):            comparison-operators.
                                                             (line  107)
* GREATEST():                            comparison-operators.
                                                             (line  211)
* GROUP BY:                              group-by-optimization.
                                                             (line   11)
* GROUP BY functions:                    group-by-functions. (line    6)
* GROUP BY, aliases in:                  group-by-hidden-fields.
                                                             (line   51)
* GROUP BY, extensions to standard SQL <1>: select.          (line  177)
* GROUP BY, extensions to standard SQL:  group-by-hidden-fields.
                                                             (line    6)
* GROUP_CONCAT():                        group-by-functions. (line  129)
* grouping, expressions:                 operator-precedence.
                                                             (line   37)
* HANDLER:                               handler.            (line    6)
* Handlers:                              declare-handlers.   (line    6)
* handling, errors:                      udf-return-values.  (line    6)
* Has read all relay log; waiting for the slave I/O thread to update it, thread state: slave-sql-thread-states.
                                                             (line   18)
* Has sent all binlog to slave; waiting for binlog to be updated, thread state: master-thread-states.
                                                             (line   22)
* hash partitioning:                     partitioning-hash.  (line   10)
* hash partitions, managing:             partitioning-management-hash-key.
                                                             (line    6)
* hash partitions, splitting and merging: partitioning-management-hash-key.
                                                             (line    6)
* HAVING:                                select.             (line  191)
* header option, ndb_select_all:         mysql-cluster-utilities-ndb-select-all.
                                                             (line   38)
* header_file option, comp_err:          comp-err.           (line   42)
* HEAP storage engine <1>:               memory-storage-engine.
                                                             (line    6)
* HEAP storage engine:                   storage-engines.    (line   21)
* HeartbeatIntervalDbApi:                mysql-cluster-ndbd-definition.
                                                             (line  998)
* HeartbeatIntervalDbDb:                 mysql-cluster-ndbd-definition.
                                                             (line  982)
* HELP command (MySQL Cluster):          mysql-cluster-mgm-client-commands.
                                                             (line   20)
* help command, mysql:                   mysql-commands.     (line   52)
* help option, comp_err:                 comp-err.           (line   24)
* help option, my_print_defaults:        my-print-defaults.  (line   23)
* help option, myisam_ftdump:            myisam-ftdump.      (line   47)
* help option, myisamchk:                myisamchk-general-options.
                                                             (line   11)
* help option, myisampack:               myisampack.         (line   44)
* help option, mysql:                    mysql-command-options.
                                                             (line  126)
* help option, mysql_explain_log:        mysql-convert-table-format.
                                                             (line   25)
* help option, mysql_find_rows:          mysql-find-rows.    (line   27)
* help option, mysql_setpermission:      mysql-setpermission.
                                                             (line   27)
* help option, mysql_upgrade:            mysql-upgrade.      (line   69)
* help option, mysql_waitpid:            mysql-waitpid.      (line   26)
* help option, mysqlaccess:              mysqlaccess.        (line   59)
* help option, mysqladmin:               mysqladmin.         (line  294)
* help option, mysqlbinlog:              mysqlbinlog.        (line  111)
* help option, mysqlcheck:               mysqlcheck.         (line  153)
* help option, mysqld:                   server-options.     (line   49)
* help option, mysqld_multi:             mysqld-multi.       (line   81)
* help option, mysqld_safe:              mysqld-safe.        (line  106)
* help option, mysqldump:                mysqldump.          (line  255)
* help option, mysqlhotcopy:             mysqlhotcopy.       (line   68)
* help option, mysqlimport:              mysqlimport.        (line  106)
* help option, mysqlmanager:             instance-manager-command-options.
                                                             (line   23)
* help option, mysqlshow:                mysqlshow.          (line   97)
* help option, mysqlslap:                mysqlslap.          (line  138)
* help option, perror:                   perror.             (line   39)
* help option, resolve_stack_dump:       resolve-stack-dump. (line   20)
* help option, resolveip:                resolveip.          (line   15)
* HELP statement:                        help.               (line    6)
* HEX() <1>:                             mathematical-functions.
                                                             (line  226)
* HEX():                                 string-functions.   (line  296)
* hex-blob option, mysqldump:            mysqldump.          (line  482)
* hexadecimal values:                    hexadecimal-values. (line    6)
* hexdump option, mysqlbinlog:           mysqlbinlog.        (line  174)
* HIGH_NOT_PRECEDENCE SQL mode:          server-sql-mode.    (line  120)
* HIGH_PRIORITY:                         select.             (line  412)
* hints:                                 extensions-to-ansi. (line    6)
* hints, index <1>:                      index-hints.        (line    6)
* hints, index:                          select.             (line  115)
* history of MySQL:                      history.            (line    6)
* HOME environment variable <1>:         mysql-command-options.
                                                             (line  566)
* HOME environment variable:             environment-variables.
                                                             (line   18)
* host option:                           connecting.         (line  106)
* host option, mysql:                    mysql-command-options.
                                                             (line  231)
* host option, mysql_explain_log:        mysql-convert-table-format.
                                                             (line   33)
* host option, mysql_setpermission:      mysql-setpermission.
                                                             (line   31)
* host option, mysqlaccess:              mysqlaccess.        (line   86)
* host option, mysqladmin:               mysqladmin.         (line  329)
* host option, mysqlbinlog:              mysqlbinlog.        (line  180)
* host option, mysqlcheck:               mysqlcheck.         (line  267)
* host option, mysqldump:                mysqldump.          (line  477)
* host option, mysqlhotcopy:             mysqlhotcopy.       (line  105)
* host option, mysqlimport:              mysqlimport.        (line  167)
* host option, mysqlshow:                mysqlshow.          (line  136)
* host option, mysqlslap:                mysqlslap.          (line  256)
* host option, ndb_config:               mysql-cluster-utilities-ndb-config.
                                                             (line   66)
* host table:                            request-access.     (line  146)
* host table, sorting:                   request-access.     (line   49)
* Host*SciId* parameters:                mysql-cluster-sci-definition.
                                                             (line   30)
* host.frm, problems finding:            unix-post-installation.
                                                             (line  122)
* HostName <1>:                          mysql-cluster-api-definition.
                                                             (line   38)
* HostName <2>:                          mysql-cluster-ndbd-definition.
                                                             (line   47)
* HostName:                              mysql-cluster-mgm-definition.
                                                             (line   33)
* HostName (MySQL Cluster):              mysql-cluster-security-networking-issues.
                                                             (line   40)
* hostname caching:                      dns.                (line    6)
* hostname, default:                     connecting.         (line    6)
* HOUR():                                date-and-time-functions.
                                                             (line  610)
* howto option, mysqlaccess:             mysqlaccess.        (line   90)
* html option, mysql:                    mysql-command-options.
                                                             (line  235)
* i-am-a-dummy option, mysql:            mysql-command-options.
                                                             (line  388)
* icc, and MySQL Cluster support>:       porting.            (line   53)
* Id <1>:                                mysql-cluster-api-definition.
                                                             (line   26)
* Id <2>:                                mysql-cluster-ndbd-definition.
                                                             (line   35)
* Id:                                    mysql-cluster-mgm-definition.
                                                             (line   16)
* id option, ndb_config:                 mysql-cluster-utilities-ndb-config.
                                                             (line   71)
* ID, unique:                            getting-unique-id.  (line    6)
* identifiers:                           identifiers.        (line   13)
* identifiers, case sensitivity:         identifier-case-sensitivity.
                                                             (line    6)
* identifiers, quoting:                  identifiers.        (line   20)
* IF:                                    if-statement.       (line    6)
* IF():                                  control-flow-functions.
                                                             (line   46)
* IFNULL():                              control-flow-functions.
                                                             (line   98)
* IGNORE INDEX:                          index-hints.        (line    6)
* IGNORE KEY:                            index-hints.        (line    6)
* ignore option, mysqlimport:            mysqlimport.        (line  172)
* IGNORE, with partitioned tables:       insert.             (line  251)
* ignore-lines option, mysqlimport:      mysqlimport.        (line  176)
* ignore-spaces option, mysql:           mysql-command-options.
                                                             (line  239)
* ignore-table option, mysqldump:        mysqldump.          (line  488)
* IGNORE_SPACE SQL mode:                 server-sql-mode.    (line  135)
* implicit default values:               data-type-defaults. (line    6)
* IMPORT TABLESPACE <1>:                 multiple-tablespaces.
                                                             (line   60)
* IMPORT TABLESPACE:                     alter-table.        (line  523)
* importing, data:                       batch-commands.     (line    6)
* IN <1>:                                any-in-some-subqueries.
                                                             (line    6)
* IN:                                    comparison-operators.
                                                             (line  226)
* in_file option, comp_err:              comp-err.           (line   46)
* increasing with replication, speed:    replication.        (line   13)
* increasing, performance:               replication-faq.    (line   31)
* index hints <1>:                       index-hints.        (line    6)
* index hints:                           select.             (line  115)
* index join type, optimizer:            using-explain.      (line  254)
* index, deleting <1>:                   drop-index.         (line    6)
* index, deleting:                       alter-table.        (line  402)
* index_merge join type, optimizer:      using-explain.      (line  204)
* index_subquery join type, optimizer:   using-explain.      (line  222)
* indexes:                               create-index.       (line    6)
* indexes, and BLOB columns <1>:         create-table.       (line  427)
* indexes, and BLOB columns:             indexes.            (line   15)
* indexes, and IS NULL:                  mysql-indexes.      (line  132)
* indexes, and LIKE:                     mysql-indexes.      (line  106)
* indexes, and NULL values:              create-table.       (line  410)
* indexes, and TEXT columns <1>:         create-table.       (line  427)
* indexes, and TEXT columns:             indexes.            (line   15)
* indexes, assigning to key cache:       cache-index.        (line    6)
* indexes, block size:                   server-system-variables.
                                                             (line 1837)
* indexes, columns:                      indexes.            (line    6)
* indexes, leftmost prefix of:           mysql-indexes.      (line   86)
* indexes, multi-column:                 multiple-column-indexes.
                                                             (line    6)
* indexes, multiple-part:                create-index.       (line    6)
* indexes, names:                        identifiers.        (line   13)
* indexes, use of:                       mysql-indexes.      (line    6)
* IndexMemory <1>:                       mysql-cluster-config-lcp-params.
                                                             (line    6)
* IndexMemory:                           mysql-cluster-ndbd-definition.
                                                             (line  247)
* INET_ATON():                           miscellaneous-functions.
                                                             (line   89)
* INET_NTOA():                           miscellaneous-functions.
                                                             (line  115)
* INFO Events (MySQL Cluster):           mysql-cluster-log-events.
                                                             (line  208)
* information functions:                 information-functions.
                                                             (line    6)
* information option, myisamchk:         myisamchk-check-options.
                                                             (line   39)
* INFORMATION_SCHEMA:                    information-schema. (line   36)
* INFORMATION_SCHEMA, and security issues: mysql-cluster-security-mysql-privileges.
                                                             (line  110)
* INFORMATION_SCHEMA.ENGINES table, used with MySQL Cluster: mysql-cluster-sql-statements.
                                                             (line   33)
* INFORMATION_SCHEMA.GLOBAL_STATUS table, used with MySQL Cluster: mysql-cluster-sql-statements.
                                                             (line  155)
* INFORMATION_SCHEMA.GLOBAL_VARIABLES table, used with MySQL Cluster: mysql-cluster-sql-statements.
                                                             (line   81)
* Init DB, thread command:               thread-commands.    (line   65)
* init, thread state:                    general-thread-states.
                                                             (line  130)
* init-file option, mysqld:              server-options.     (line  569)
* Initialized, thread state:             event-scheduler-thread-states.
                                                             (line   15)
* InitialNoOfOpenFiles:                  mysql-cluster-ndbd-definition.
                                                             (line  670)
* INNER JOIN:                            join.               (line    6)
* innochecksum:                          programs-overview.  (line  160)
* InnoDB:                                innodb-overview.    (line    6)
* innodb option, mysqld:                 innodb-parameters.  (line  162)
* InnoDB storage engine <1>:             innodb.             (line   26)
* InnoDB storage engine:                 storage-engines.    (line   21)
* InnoDB tables:                         ansi-diff-transactions.
                                                             (line    6)
* InnoDB, NFS <1>:                       innodb-restrictions.
                                                             (line   16)
* InnoDB, NFS:                           innodb-configuration.
                                                             (line   49)
* InnoDB, Solaris 10 x86_64 issues:      solaris.            (line   11)
* innodb_status_file option, mysqld:     innodb-parameters.  (line  167)
* INSERT <1>:                            insert.             (line   12)
* INSERT:                                insert-speed.       (line    6)
* INSERT ... SELECT:                     insert-select.      (line    6)
* INSERT DELAYED:                        insert-delayed.     (line    6)
* INSERT statement, grant privileges:    adding-users.       (line   98)
* INSERT():                              string-functions.   (line  314)
* insert, thread state:                  delayed-insert-thread-states.
                                                             (line   73)
* insert-ignore option, mysqldump:       mysqldump.          (line  494)
* inserting, speed of:                   insert-speed.       (line    6)
* inserts, concurrent <1>:               concurrent-inserts. (line    6)
* inserts, concurrent:                   internal-locking.   (line   71)
* install option, mysqlmanager:          instance-manager-command-options.
                                                             (line   97)
* INSTALL PLUGIN:                        install-plugin.     (line    6)
* installation layouts:                  installation-layouts.
                                                             (line    6)
* installation overview:                 installing-source.  (line   16)
* installing MySQL Cluster <1>:          mysql-cluster-installing.
                                                             (line    6)
* installing MySQL Cluster <2>:          mysql-cluster-multi-install.
                                                             (line    6)
* installing MySQL Cluster:              mysql-cluster-multi-computer.
                                                             (line   15)
* installing plugins:                    install-plugin.     (line    6)
* installing, binary distribution:       installing-binary.  (line    6)
* installing, Linux RPM packages:        linux-rpm.          (line    6)
* installing, Mac OS X PKG packages:     mac-os-x-installation.
                                                             (line    6)
* installing, overview:                  installing.         (line   24)
* installing, Perl:                      perl-support.       (line   12)
* installing, Perl on Windows:           activestate-perl.   (line    6)
* installing, Solaris PKG packages:      solaris-installation.
                                                             (line    6)
* installing, source distribution:       installing-source.  (line   16)
* installing, user-defined functions:    udf-compiling.      (line    6)
* INSTR():                               string-functions.   (line  332)
* INT data type:                         numeric-type-overview.
                                                             (line  118)
* integer arithmetic:                    precision-math.     (line   14)
* INTEGER data type:                     numeric-type-overview.
                                                             (line  123)
* integers:                              number-syntax.      (line    6)
* InteriorRingN():                       polygon-property-functions.
                                                             (line   35)
* internal compiler errors:              compilation-problems.
                                                             (line   38)
* internal locking:                      internal-locking.   (line    6)
* internals:                             mysql-internals.    (line   11)
* internationalization:                  internationalization-localization.
                                                             (line   17)
* Internet Relay Chat:                   irc.                (line    6)
* Intersection():                        spatial-operators.  (line   27)
* Intersects():                          functions-that-test-spatial-relationships-between-geometries.
                                                             (line   58)
* INTERVAL():                            comparison-operators.
                                                             (line  286)
* introducer, string literal <1>:        charset-literal.    (line   11)
* introducer, string literal:            string-syntax.      (line   27)
* invalid data, constraint:              constraint-invalid-data.
                                                             (line    6)
* IRC:                                   irc.                (line    6)
* IS boolean_value:                      comparison-operators.
                                                             (line  121)
* IS NOT boolean_value:                  comparison-operators.
                                                             (line  129)
* IS NOT NULL:                           comparison-operators.
                                                             (line  165)
* IS NULL <1>:                           comparison-operators.
                                                             (line  137)
* IS NULL:                               is-null-optimization.
                                                             (line    6)
* IS NULL, and indexes:                  mysql-indexes.      (line  132)
* IS_FREE_LOCK():                        miscellaneous-functions.
                                                             (line  123)
* IS_USED_LOCK():                        miscellaneous-functions.
                                                             (line  130)
* isamlog:                               programs-overview.  (line  175)
* IsClosed():                            multilinestring-property-functions.
                                                             (line   25)
* IsEmpty():                             general-geometry-property-functions.
                                                             (line   75)
* ISNULL():                              comparison-operators.
                                                             (line  269)
* ISOLATION LEVEL:                       set-transaction.    (line    6)
* IsRing():                              linestring-property-functions.
                                                             (line   80)
* IsSimple():                            general-geometry-property-functions.
                                                             (line   81)
* ITERATE:                               iterate-statement.  (line    6)
* iterations option, mysqlslap:          mysqlslap.          (line  260)
* Japanese character sets, conversion:   faqs-cjk.           (line   25)
* Japanese, Korean, Chinese character sets, frequently asked questions: faqs-cjk.
                                                             (line    6)
* JOIN:                                  join.               (line    6)
* join option, myisampack:               myisampack.         (line   74)
* keepold option, mysqlhotcopy:          mysqlhotcopy.       (line  111)
* key cache, assigning indexes to:       cache-index.        (line    6)
* Key cache, MyISAM:                     myisam-key-cache.   (line   15)
* key partitioning:                      partitioning-key.   (line    6)
* key partitions, managing:              partitioning-management-hash-key.
                                                             (line    6)
* key partitions, splitting and merging: partitioning-management-hash-key.
                                                             (line    6)
* key space, MyISAM:                     key-space.          (line    6)
* key_buffer_size myisamchk variable:    myisamchk-general-options.
                                                             (line   45)
* KEY_COLUMN_USAGE, INFORMATION_SCHEMA table: key-column-usage-table.
                                                             (line    6)
* keys:                                  indexes.            (line    6)
* keys option, mysqlshow:                mysqlshow.          (line  140)
* keys, foreign <1>:                     example-foreign-keys.
                                                             (line    6)
* keys, foreign:                         ansi-diff-foreign-keys.
                                                             (line    6)
* keys, multi-column:                    multiple-column-indexes.
                                                             (line    6)
* keys, searching on two:                searching-on-two-keys.
                                                             (line    6)
* keys-used option, myisamchk:           myisamchk-repair-options.
                                                             (line   37)
* keywords:                              reserved-words.     (line    6)
* KILL:                                  kill.               (line    6)
* Kill, thread command:                  thread-commands.    (line   69)
* Killed, thread state:                  general-thread-states.
                                                             (line  135)
* Killing slave, thread state:           slave-connection-thread-states.
                                                             (line   19)
* known errors:                          bugs.               (line   11)
* Korean:                                faqs-cjk.           (line   39)
* Korean, Chinese, Japanese character sets, frequently asked questions: faqs-cjk.
                                                             (line    6)
* language option, mysqld:               server-options.     (line  589)
* language support, error messages:      error-message-language.
                                                             (line    6)
* large-pages option, mysqld:            server-options.     (line  605)
* last row, unique ID:                   getting-unique-id.  (line    6)
* LAST_DAY():                            date-and-time-functions.
                                                             (line  622)
* LAST_INSERT_ID() <1>:                  insert.             (line  197)
* LAST_INSERT_ID():                      ansi-diff-transactions.
                                                             (line  160)
* LAST_INSERT_ID() and stored routines:  stored-procedure-last-insert-id.
                                                             (line    6)
* LAST_INSERT_ID() and triggers:         stored-procedure-last-insert-id.
                                                             (line    6)
* LAST_INSERT_ID([<replaceable>expr</replaceable>]): information-functions.
                                                             (line  249)
* layout of installation:                installation-layouts.
                                                             (line    6)
* LCASE():                               string-functions.   (line  346)
* LD_LIBRARY_PATH environment variable:  perl-support-problems.
                                                             (line   23)
* LD_RUN_PATH environment variable <1>:  perl-support-problems.
                                                             (line   23)
* LD_RUN_PATH environment variable <2>:  environment-variables.
                                                             (line   18)
* LD_RUN_PATH environment variable <3>:  solaris.            (line  151)
* LD_RUN_PATH environment variable:      source-notes-linux. (line   97)
* LEAST():                               comparison-operators.
                                                             (line  300)
* LEAVE:                                 leave-statement.    (line    6)
* ledir option, mysqld_safe:             mysqld-safe.        (line  148)
* LEFT JOIN <1>:                         join.               (line    6)
* LEFT JOIN:                             left-join-optimization.
                                                             (line    6)
* LEFT OUTER JOIN:                       join.               (line    6)
* LEFT():                                string-functions.   (line  350)
* leftmost prefix of indexes:            mysql-indexes.      (line   86)
* legal names:                           identifiers.        (line   13)
* length option, myisam_ftdump:          myisam-ftdump.      (line   59)
* LENGTH():                              string-functions.   (line  358)
* less than (<):                         comparison-operators.
                                                             (line  100)
* less than or equal (<=):               comparison-operators.
                                                             (line   93)
* libmysqld:                             libmysqld.          (line   14)
* libmysqld, options:                    libmysqld-options.  (line    6)
* libraries, list of:                    used-libraries.     (line    6)
* library, mysqlclient:                  apis.               (line   17)
* library, mysqld:                       apis.               (line   17)
* LIKE:                                  string-comparison-functions.
                                                             (line   18)
* LIKE, and indexes:                     mysql-indexes.      (line  106)
* LIKE, and wildcards:                   mysql-indexes.      (line  106)
* LIMIT <1>:                             select.             (line  248)
* LIMIT <2>:                             information-functions.
                                                             (line  172)
* LIMIT:                                 limit-optimization. (line    6)
* limitations of MySQL Cluster:          mysql-cluster-limitations.
                                                             (line   20)
* limitations, design:                   design-limitations. (line    6)
* limitations, MySQL Limitations:        limits.             (line   12)
* limitations, replication:              replication-features.
                                                             (line   33)
* limits, file-size:                     full-table.         (line    6)
* limits, MySQL Limits, limits in MySQL: limits.             (line   12)
* line-numbers option, mysql:            mysql-command-options.
                                                             (line  245)
* linear hash partitioning:              partitioning-linear-hash.
                                                             (line    6)
* linear key partitioning:               partitioning-key.   (line   99)
* linefeed (\n) <1>:                     load-data.          (line  414)
* linefeed (\n):                         string-syntax.      (line   52)
* LineFromText():                        gis-wkt-functions.  (line   25)
* LineFromWKB():                         gis-wkb-functions.  (line   26)
* lines-terminated-by option, mysqldump <1>: mysqlimport.    (line  180)
* lines-terminated-by option, mysqldump: mysqldump.          (line  498)
* LINESTRING data type:                  mysql-spatial-datatypes.
                                                             (line    6)
* LineString():                          gis-mysql-specific-functions.
                                                             (line   20)
* LineStringFromText():                  gis-wkt-functions.  (line   25)
* LineStringFromWKB():                   gis-wkb-functions.  (line   26)
* linking:                               building-clients.   (line    6)
* linking, errors:                       link-errors.        (line    6)
* linking, problems:                     c-api-linking-problems.
                                                             (line    6)
* linking, speed:                        compile-and-link-options.
                                                             (line    6)
* links, symbolic:                       symbolic-links.     (line   12)
* Linux, binary distribution:            binary-notes-linux. (line    6)
* Linux, source distribution:            source-notes-linux. (line    6)
* list partitioning:                     partitioning-list.  (line    6)
* list partitions, adding and dropping:  partitioning-management-range-list.
                                                             (line    6)
* list partitions, managing:             partitioning-management-range-list.
                                                             (line    6)
* list-users option, mysqlmanager:       instance-manager-command-options.
                                                             (line  102)
* literals:                              literals.           (line   15)
* LN():                                  mathematical-functions.
                                                             (line  233)
* LOAD DATA FROM MASTER:                 load-data-from-master.
                                                             (line    6)
* LOAD DATA INFILE <1>:                  problems-with-null. (line   51)
* LOAD DATA INFILE:                      load-data.          (line    6)
* LOAD INDEX INTO CACHE, and partitioning: partitioning-limitations.
                                                             (line  296)
* LOAD TABLE FROM MASTER:                load-table-from-master.
                                                             (line    6)
* LOAD_FILE():                           string-functions.   (line  368)
* loading, tables:                       loading-tables.     (line    6)
* local checkpoints (MySQL Cluster):     mysql-cluster-config-lcp-params.
                                                             (line    6)
* local option, mysqlimport:             mysqlimport.        (line  189)
* local-infile option, mysql:            mysql-command-options.
                                                             (line  250)
* local-infile option, mysqld:           privileges-options. (line   40)
* local-load option, mysqlbinlog:        mysqlbinlog.        (line  184)
* localization:                          internationalization-localization.
                                                             (line   17)
* localstatedir option, configure:       configure-options.  (line  308)
* LOCALTIME:                             date-and-time-functions.
                                                             (line  637)
* LOCALTIMESTAMP:                        date-and-time-functions.
                                                             (line  641)
* LOCATE():                              string-functions.   (line  387)
* LOCK IN SHARE MODE:                    select.             (line  393)
* lock option, ndb_select_all:           mysql-cluster-utilities-ndb-select-all.
                                                             (line   14)
* LOCK TABLES:                           lock-tables.        (line    6)
* lock-all-tables option, mysqldump:     mysqldump.          (line  504)
* lock-directory option, mysqlslap:      mysqlslap.          (line  264)
* lock-tables option, mysqldump:         mysqldump.          (line  511)
* lock-tables option, mysqlimport:       mysqlimport.        (line  200)
* Locked, thread state:                  general-thread-states.
                                                             (line  144)
* LockExecuteThreadToCPU:                mysql-cluster-ndbd-definition.
                                                             (line 1583)
* locking:                               system-optimization.
                                                             (line   24)
* locking methods:                       internal-locking.   (line    6)
* locking, external <1>:                 general-thread-states.
                                                             (line  272)
* locking, external <2>:                 external-locking.   (line    6)
* locking, external <3>:                 crash-recovery.     (line    6)
* locking, external <4>:                 server-system-variables.
                                                             (line 3471)
* locking, external:                     server-options.     (line  506)
* locking, internal:                     internal-locking.   (line    6)
* locking, row-level <1>:                internal-locking.   (line    6)
* locking, row-level:                    ansi-diff-transactions.
                                                             (line  168)
* locking, table-level:                  internal-locking.   (line    6)
* LockMaintThreadsToCPU:                 mysql-cluster-ndbd-definition.
                                                             (line 1591)
* LockPagesInMainMemory:                 mysql-cluster-ndbd-definition.
                                                             (line  788)
* log files <1>:                         log-files.          (line   15)
* log files:                             configure-options.  (line    6)
* log files (MySQL Cluster):             mysql-cluster-ndbd-process.
                                                             (line   16)
* log files, maintaining:                log-file-maintenance.
                                                             (line    6)
* log option, mysqld:                    server-options.     (line  635)
* log option, mysqld_multi:              mysqld-multi.       (line  101)
* log option, mysqlmanager:              instance-manager-command-options.
                                                             (line  107)
* LOG():                                 mathematical-functions.
                                                             (line  247)
* log, changes:                          news.               (line   16)
* log-bin option, mysqld:                server-options.     (line  654)
* log-bin-index option, mysqld:          server-options.     (line  669)
* log-bin-trust-function-creators option, mysqld: server-options.
                                                             (line  678)
* log-error option, mysqld:              server-options.     (line  696)
* log-error option, mysqld_safe:         mysqld-safe.        (line  153)
* log-error option, mysqldump:           mysqldump.          (line  525)
* log-isam option, mysqld:               server-options.     (line  711)
* log-long-format option, mysqld:        server-options.     (line  719)
* log-output option, mysqld:             server-options.     (line  731)
* log-queries-not-using-indexes option, mysqld: server-options.
                                                             (line  764)
* log-short-format option, mysqld:       server-options.     (line  778)
* log-slave-updates option, mysqld:      replication-options.
                                                             (line  126)
* log-slow-admin-statements option, mysqld: server-options.  (line  788)
* log-slow-queries option, mysqld:       server-options.     (line  797)
* log-slow-slave-statements option, mysqld: server-options.  (line  818)
* log-tc option, mysqld:                 server-options.     (line  831)
* log-tc-size option, mysqld:            server-options.     (line  843)
* log-warnings option, mysqld <1>:       replication-options.
                                                             (line  146)
* log-warnings option, mysqld:           server-options.     (line  853)
* LOG10():                               mathematical-functions.
                                                             (line  287)
* LOG2():                                mathematical-functions.
                                                             (line  274)
* LogDestination:                        mysql-cluster-mgm-definition.
                                                             (line   40)
* logging commands (MySQL Cluster):      mysql-cluster-logging-management-commands.
                                                             (line    6)
* logging slow query, thread state:      general-thread-states.
                                                             (line  148)
* logical operators:                     logical-operators.  (line    6)
* login, thread state:                   general-thread-states.
                                                             (line  152)
* LogLevelCheckpoint (MySQL Cluster configuration parameter): mysql-cluster-ndbd-definition.
                                                             (line 1412)
* LogLevelCongestion:                    mysql-cluster-ndbd-definition.
                                                             (line 1440)
* LogLevelConnection (MySQL Cluster configuration parameter): mysql-cluster-ndbd-definition.
                                                             (line 1425)
* LogLevelError:                         mysql-cluster-ndbd-definition.
                                                             (line 1432)
* LogLevelInfo:                          mysql-cluster-ndbd-definition.
                                                             (line 1448)
* LogLevelNodeRestart (MySQL Cluster configuration parameter): mysql-cluster-ndbd-definition.
                                                             (line 1419)
* LogLevelShutdown:                      mysql-cluster-ndbd-definition.
                                                             (line 1397)
* LogLevelStartup:                       mysql-cluster-ndbd-definition.
                                                             (line 1390)
* LogLevelStatistic (MySQL Cluster configuration parameter): mysql-cluster-ndbd-definition.
                                                             (line 1404)
* LONG data type:                        blob.               (line    6)
* Long Data, thread command:             thread-commands.    (line   73)
* LONGBLOB data type:                    string-type-overview.
                                                             (line  201)
* LongMessageBuffer:                     mysql-cluster-ndbd-definition.
                                                             (line  578)
* LONGTEXT data type:                    string-type-overview.
                                                             (line  210)
* LOOP:                                  loop-statement.     (line    6)
* loops option, ndb_show_tables:         mysql-cluster-utilities-ndb-show-tables.
                                                             (line   17)
* lost connection errors:                error-lost-connection.
                                                             (line    6)
* low-priority option, mysqlimport:      mysqlimport.        (line  205)
* low-priority-updates option, mysqld:   server-options.     (line  873)
* LOWER():                               string-functions.   (line  404)
* LPAD():                                string-functions.   (line  427)
* LTRIM():                               string-functions.   (line  438)
* Mac OS X:                              myodbc-connector.   (line   17)
* Mac OS X, installation:                mac-os-x-installation.
                                                             (line    6)
* mailing list address:                  introduction.       (line   77)
* mailing lists:                         mailing-lists.      (line   10)
* mailing lists, archive location:       mailing-lists.      (line   10)
* mailing lists, guidelines:             mailing-list-use.   (line    6)
* main features of MySQL:                features.           (line    6)
* maintaining, log files:                log-file-maintenance.
                                                             (line    6)
* maintaining, tables:                   maintenance-schedule.
                                                             (line    6)
* make_binary_distribution:              programs-overview.  (line   70)
* MAKE_SET():                            string-functions.   (line  447)
* make_win_bin_dist:                     programs-overview.  (line   76)
* make_win_bin_dist, debug option:       make-win-bin-dist.  (line   36)
* make_win_bin_dist, embedded option:    make-win-bin-dist.  (line   41)
* make_win_bin_dist, exe-suffix option:  make-win-bin-dist.  (line   46)
* make_win_bin_dist, no-debug option:    make-win-bin-dist.  (line   51)
* make_win_bin_dist, no-embedded option: make-win-bin-dist.  (line   55)
* make_win_bin_dist, only-debug option:  make-win-bin-dist.  (line   59)
* MAKEDATE():                            date-and-time-functions.
                                                             (line  645)
* MAKETIME():                            date-and-time-functions.
                                                             (line  657)
* Making temp file, thread state:        slave-sql-thread-states.
                                                             (line   25)
* malicious SQL statements, and MySQL Cluster: mysql-cluster-security-mysql-privileges.
                                                             (line   78)
* management node (MySQL Cluster), defined: mysql-cluster-basics.
                                                             (line    6)
* managing MySQL Cluster:                mysql-cluster-management.
                                                             (line   15)
* managing MySQL Cluster processes:      mysql-cluster-process-management.
                                                             (line   14)
* manual, available formats:             manual-info.        (line   28)
* manual, online location:               manual-info.        (line    6)
* manual, typographical conventions:     manual-conventions. (line    8)
* master-connect-retry option, mysqld:   replication-options.
                                                             (line  156)
* master-data option, mysqldump:         mysqldump.          (line  530)
* master-host option, mysqld:            replication-options.
                                                             (line  170)
* master-info-file option, mysqld:       replication-options.
                                                             (line  179)
* master-password option, mysqld:        replication-options.
                                                             (line  185)
* master-port option, mysqld:            replication-options.
                                                             (line  195)
* master-retry-count option, mysqld:     replication-options.
                                                             (line  204)
* master-ssl option, mysqld:             replication-options.
                                                             (line  219)
* master-ssl-ca option, mysqld:          replication-options.
                                                             (line  219)
* master-ssl-capath option, mysqld:      replication-options.
                                                             (line  219)
* master-ssl-cert option, mysqld:        replication-options.
                                                             (line  219)
* master-ssl-cipher option, mysqld:      replication-options.
                                                             (line  219)
* master-ssl-key option, mysqld:         replication-options.
                                                             (line  219)
* master-user option, mysqld:            replication-options.
                                                             (line  234)
* MASTER_POS_WAIT() <1>:                 master-pos-wait.    (line    6)
* MASTER_POS_WAIT():                     miscellaneous-functions.
                                                             (line  136)
* MATCH ... AGAINST():                   fulltext-search.    (line   15)
* matching, patterns:                    pattern-matching.   (line    6)
* math:                                  precision-math.     (line   14)
* mathematical functions:                mathematical-functions.
                                                             (line   52)
* MAX():                                 group-by-functions. (line  180)
* MAX(DISTINCT):                         group-by-functions. (line  180)
* max-binlog-dump-events option, mysqld: server-options.     (line  908)
* max-record-length option, myisamchk:   myisamchk-repair-options.
                                                             (line   53)
* max-relay-log-size option, mysqld:     replication-options.
                                                             (line  245)
* max_allowed_packet variable:           mysql-command-options.
                                                             (line  546)
* MAX_CONNECTIONS_PER_HOUR:              user-resources.     (line    6)
* max_join_size variable:                mysql-command-options.
                                                             (line  551)
* MAX_QUERIES_PER_HOUR:                  user-resources.     (line    6)
* MAX_UPDATES_PER_HOUR:                  user-resources.     (line    6)
* MAX_USER_CONNECTIONS:                  user-resources.     (line    6)
* MaxBufferedEpochs:                     mysql-cluster-ndbd-definition.
                                                             (line 1081)
* MAXDB SQL mode:                        server-sql-mode.    (line  461)
* maximum memory used:                   mysqladmin.         (line  215)
* maximums, maximum columns per table:   column-count-limit. (line    6)
* maximums, maximum tables per join:     joins-limits.       (line    6)
* MaxNoOfAttributes:                     mysql-cluster-ndbd-definition.
                                                             (line  694)
* MaxNoOfConcurrentIndexOperations:      mysql-cluster-ndbd-definition.
                                                             (line  475)
* MaxNoOfConcurrentOperations:           mysql-cluster-ndbd-definition.
                                                             (line  399)
* MaxNoOfConcurrentScans:                mysql-cluster-ndbd-definition.
                                                             (line  538)
* MaxNoOfConcurrentTransactions:         mysql-cluster-ndbd-definition.
                                                             (line  364)
* MaxNoOfFiredTriggers:                  mysql-cluster-ndbd-definition.
                                                             (line  492)
* MaxNoOfIndexes:                        mysql-cluster-ndbd-definition.
                                                             (line  770)
* MaxNoOfLocalOperations:                mysql-cluster-ndbd-definition.
                                                             (line  452)
* MaxNoOfLocalScans:                     mysql-cluster-ndbd-definition.
                                                             (line  562)
* MaxNoOfOpenFiles:                      mysql-cluster-ndbd-definition.
                                                             (line  662)
* MaxNoOfOrderedIndexes:                 mysql-cluster-ndbd-definition.
                                                             (line  733)
* MaxNoOfSavedMessages:                  mysql-cluster-ndbd-definition.
                                                             (line  677)
* MaxNoOfTables:                         mysql-cluster-ndbd-definition.
                                                             (line  719)
* MaxNoOfTriggers:                       mysql-cluster-ndbd-definition.
                                                             (line  755)
* MaxNoOfUniqueHashIndexes:              mysql-cluster-ndbd-definition.
                                                             (line  744)
* MaxScanBatchSize:                      mysql-cluster-api-definition.
                                                             (line   95)
* MBR:                                   relations-on-geometry-mbr.
                                                             (line    6)
* MBRContains():                         relations-on-geometry-mbr.
                                                             (line   10)
* MBRDisjoint():                         relations-on-geometry-mbr.
                                                             (line   25)
* MBREqual():                            relations-on-geometry-mbr.
                                                             (line   30)
* MBRIntersects():                       relations-on-geometry-mbr.
                                                             (line   35)
* MBROverlaps():                         relations-on-geometry-mbr.
                                                             (line   40)
* MBRTouches():                          relations-on-geometry-mbr.
                                                             (line   48)
* MBRWithin():                           relations-on-geometry-mbr.
                                                             (line   56)
* MD5():                                 encryption-functions.
                                                             (line  220)
* medium-check option, myisamchk:        myisamchk-check-options.
                                                             (line   43)
* medium-check option, mysqlcheck:       mysqlcheck.         (line  271)
* MEDIUMBLOB data type:                  string-type-overview.
                                                             (line  187)
* MEDIUMINT data type:                   numeric-type-overview.
                                                             (line  113)
* MEDIUMTEXT data type:                  string-type-overview.
                                                             (line  193)
* memlock option, mysqld:                server-options.     (line  916)
* MEMORY storage engine <1>:             memory-storage-engine.
                                                             (line    6)
* MEMORY storage engine:                 storage-engines.    (line   21)
* memory usage, myisamchk:               myisamchk-memory.   (line    6)
* memory use <1>:                        memory-use.         (line    6)
* memory use:                            mysqladmin.         (line  209)
* memory use, in MySQL Cluster:          mysql-cluster-limitations-limits.
                                                             (line    9)
* MemReportFrequency:                    mysql-cluster-ndbd-definition.
                                                             (line 1455)
* MERGE storage engine <1>:              merge-storage-engine.
                                                             (line   10)
* MERGE storage engine:                  storage-engines.    (line   21)
* MERGE tables, defined:                 merge-storage-engine.
                                                             (line   10)
* metadata, database:                    information-schema. (line   36)
* method option, mysqlhotcopy:           mysqlhotcopy.       (line  115)
* methods, locking:                      internal-locking.   (line    6)
* mgmd (MySQL Cluster), defined:         mysql-cluster-basics.
                                                             (line    6)
* MICROSECOND():                         date-and-time-functions.
                                                             (line  665)
* Microsoft Access:                      myodbc-usagenotes-apptips-microsoft-access.
                                                             (line    6)
* Microsoft ADO:                         myodbc-usagenotes-apptips-microsoft-ado.
                                                             (line    6)
* Microsoft Excel:                       myodbc-usagenotes-apptips-microsoft-excel.
                                                             (line    6)
* Microsoft Visual Basic:                myodbc-usagenotes-apptips-microsoft-visualbasic.
                                                             (line    6)
* Microsoft Visual InterDev:             myodbc-usagenotes-apptips-microsoft-visualinterdev.
                                                             (line    6)
* MID():                                 string-functions.   (line  464)
* MIN():                                 group-by-functions. (line  199)
* MIN(DISTINCT):                         group-by-functions. (line  199)
* min-examined-row-limit option, mysqld: server-options.     (line  892)
* Minimum Bounding Rectangle:            relations-on-geometry-mbr.
                                                             (line    6)
* minus, unary (-):                      arithmetic-functions.
                                                             (line   57)
* MINUTE():                              date-and-time-functions.
                                                             (line  675)
* mirror sites:                          getting-mysql.      (line    6)
* miscellaneous functions:               miscellaneous-functions.
                                                             (line    6)
* MIT-pthreads:                          mit-pthreads.       (line    6)
* MLineFromText():                       gis-wkt-functions.  (line   30)
* MLineFromWKB():                        gis-wkb-functions.  (line   31)
* MOD (modulo):                          mathematical-functions.
                                                             (line  300)
* MOD():                                 mathematical-functions.
                                                             (line  300)
* modes, batch:                          batch-mode.         (line    6)
* modulo (%):                            mathematical-functions.
                                                             (line  300)
* modulo (MOD):                          mathematical-functions.
                                                             (line  300)
* monitor, terminal:                     tutorial.           (line   17)
* monitoring-interval option, mysqlmanager: instance-manager-command-options.
                                                             (line  125)
* Mono:                                  connector-net.      (line   15)
* MONTH():                               date-and-time-functions.
                                                             (line  682)
* MONTHNAME():                           date-and-time-functions.
                                                             (line  691)
* MPointFromText():                      gis-wkt-functions.  (line   35)
* MPointFromWKB():                       gis-wkb-functions.  (line   36)
* MPolyFromText():                       gis-wkt-functions.  (line   40)
* MPolyFromWKB():                        gis-wkb-functions.  (line   41)
* mSQL compatibility:                    string-comparison-functions.
                                                             (line  148)
* MSSQL SQL mode:                        server-sql-mode.    (line  467)
* multi-byte character sets:             cannot-initialize-character-set.
                                                             (line    6)
* multi-byte character sets, and MySQL Cluster (replication): mysql-cluster-replication-issues.
                                                             (line   47)
* multi-byte characters:                 multi-byte-characters.
                                                             (line    6)
* multi-column indexes:                  multiple-column-indexes.
                                                             (line    6)
* MULTILINESTRING data type:             mysql-spatial-datatypes.
                                                             (line    6)
* MultiLineString():                     gis-mysql-specific-functions.
                                                             (line   27)
* MultiLineStringFromText():             gis-wkt-functions.  (line   30)
* MultiLineStringFromWKB():              gis-wkb-functions.  (line   31)
* multiple servers:                      multiple-servers.   (line   12)
* multiple-part index:                   create-index.       (line    6)
* multiplication (*):                    arithmetic-functions.
                                                             (line   70)
* MULTIPOINT data type:                  mysql-spatial-datatypes.
                                                             (line    6)
* MultiPoint():                          gis-mysql-specific-functions.
                                                             (line   33)
* MultiPointFromText():                  gis-wkt-functions.  (line   35)
* MultiPointFromWKB():                   gis-wkb-functions.  (line   36)
* MULTIPOLYGON data type:                mysql-spatial-datatypes.
                                                             (line    6)
* MultiPolygon():                        gis-mysql-specific-functions.
                                                             (line   38)
* MultiPolygonFromText():                gis-wkt-functions.  (line   40)
* MultiPolygonFromWKB():                 gis-wkb-functions.  (line   41)
* My, derivation:                        history.            (line    6)
* my.cnf file:                           replication-features.
                                                             (line   33)
* my.cnf, and MySQL Cluster <1>:         mysql-cluster-config-example.
                                                             (line    6)
* my.cnf, and MySQL Cluster <2>:         mysql-cluster-config-file.
                                                             (line   19)
* my.cnf, and MySQL Cluster:             mysql-cluster-multi-config.
                                                             (line    6)
* my.cnf, in MySQL Cluster:              mysql-cluster-mysqld-process.
                                                             (line   32)
* my_bool C type:                        c-api-datatypes.    (line   62)
* my_bool values, printing:              c-api-datatypes.    (line   62)
* my_init():                             my-init.            (line    6)
* my_print_defaults:                     programs-overview.  (line  256)
* my_print_defaults, config-file option: my-print-defaults.  (line   27)
* my_print_defaults, debug option:       my-print-defaults.  (line   33)
* my_print_defaults, defaults-extra-file option: my-print-defaults.
                                                             (line   39)
* my_print_defaults, defaults-file option: my-print-defaults.
                                                             (line   29)
* my_print_defaults, defaults-group-suffix option: my-print-defaults.
                                                             (line   46)
* my_print_defaults, extra-file option:  my-print-defaults.  (line   41)
* my_print_defaults, help option:        my-print-defaults.  (line   23)
* my_print_defaults, no-defaults option: my-print-defaults.  (line   51)
* my_print_defaults, verbose option:     my-print-defaults.  (line   55)
* my_print_defaults, version option:     my-print-defaults.  (line   59)
* my_ulonglong C type:                   c-api-datatypes.    (line   48)
* my_ulonglong values, printing:         c-api-datatypes.    (line   48)
* MyISAM key cache:                      myisam-key-cache.   (line   15)
* MyISAM storage engine <1>:             myisam-storage-engine.
                                                             (line   13)
* MyISAM storage engine:                 storage-engines.    (line   21)
* MyISAM, compressed tables:             compressed-format.  (line    6)
* myisam-recover option, mysqld <1>:     myisam-start.       (line   31)
* myisam-recover option, mysqld:         server-options.     (line  953)
* myisam_block_size myisamchk variable:  myisamchk-general-options.
                                                             (line   45)
* myisam_ftdump:                         programs-overview.  (line  165)
* myisam_ftdump, count option:           myisam-ftdump.      (line   51)
* myisam_ftdump, dump option:            myisam-ftdump.      (line   55)
* myisam_ftdump, help option:            myisam-ftdump.      (line   47)
* myisam_ftdump, length option:          myisam-ftdump.      (line   59)
* myisam_ftdump, stats option:           myisam-ftdump.      (line   63)
* myisam_ftdump, verbose option:         myisam-ftdump.      (line   68)
* myisamchk <1>:                         programs-overview.  (line  170)
* myisamchk:                             configure-options.  (line  435)
* myisamchk, analyze option:             myisamchk-other-options.
                                                             (line    9)
* myisamchk, backup option:              myisamchk-repair-options.
                                                             (line    8)
* myisamchk, block-search option:        myisamchk-other-options.
                                                             (line   24)
* myisamchk, character-sets-dir option:  myisamchk-repair-options.
                                                             (line   12)
* myisamchk, check option:               myisamchk-check-options.
                                                             (line    9)
* myisamchk, check-only-changed option:  myisamchk-check-options.
                                                             (line   14)
* myisamchk, correct-checksum option:    myisamchk-repair-options.
                                                             (line   17)
* myisamchk, data-file-length option:    myisamchk-repair-options.
                                                             (line   21)
* myisamchk, debug option:               myisamchk-general-options.
                                                             (line   15)
* myisamchk, description option:         myisamchk-other-options.
                                                             (line   28)
* myisamchk, example output:             table-info.         (line   37)
* myisamchk, extend-check option <1>:    myisamchk-repair-options.
                                                             (line   26)
* myisamchk, extend-check option:        myisamchk-check-options.
                                                             (line   18)
* myisamchk, fast option:                myisamchk-check-options.
                                                             (line   29)
* myisamchk, force option <1>:           myisamchk-repair-options.
                                                             (line   32)
* myisamchk, force option:               myisamchk-check-options.
                                                             (line   33)
* myisamchk, help option:                myisamchk-general-options.
                                                             (line   11)
* myisamchk, information option:         myisamchk-check-options.
                                                             (line   39)
* myisamchk, keys-used option:           myisamchk-repair-options.
                                                             (line   37)
* myisamchk, max-record-length option:   myisamchk-repair-options.
                                                             (line   53)
* myisamchk, medium-check option:        myisamchk-check-options.
                                                             (line   43)
* myisamchk, no-symlinks option:         myisamchk-repair-options.
                                                             (line   46)
* myisamchk, options:                    myisamchk-general-options.
                                                             (line    6)
* myisamchk, parallel-recover option:    myisamchk-repair-options.
                                                             (line   58)
* myisamchk, quick option:               myisamchk-repair-options.
                                                             (line   64)
* myisamchk, read-only option:           myisamchk-check-options.
                                                             (line   49)
* myisamchk, recover option:             myisamchk-repair-options.
                                                             (line   70)
* myisamchk, safe-recover option:        myisamchk-repair-options.
                                                             (line   83)
* myisamchk, set-auto-increment[ option: myisamchk-other-options.
                                                             (line   32)
* myisamchk, set-character-set option:   myisamchk-repair-options.
                                                             (line   96)
* myisamchk, set-collation option:       myisamchk-repair-options.
                                                             (line  101)
* myisamchk, silent option:              myisamchk-general-options.
                                                             (line   20)
* myisamchk, sort-index option:          myisamchk-other-options.
                                                             (line   40)
* myisamchk, sort-records option:        myisamchk-other-options.
                                                             (line   45)
* myisamchk, sort-recover option:        myisamchk-repair-options.
                                                             (line  107)
* myisamchk, tmpdir option:              myisamchk-repair-options.
                                                             (line  112)
* myisamchk, unpack option:              myisamchk-repair-options.
                                                             (line  122)
* myisamchk, update-state option:        myisamchk-check-options.
                                                             (line   56)
* myisamchk, verbose option:             myisamchk-general-options.
                                                             (line   25)
* myisamchk, version option:             myisamchk-general-options.
                                                             (line   31)
* myisamchk, wait option:                myisamchk-general-options.
                                                             (line   35)
* myisamlog:                             programs-overview.  (line  175)
* myisampack <1>:                        compressed-format.  (line    6)
* myisampack <2>:                        silent-column-changes.
                                                             (line   62)
* myisampack:                            programs-overview.  (line  180)
* myisampack, backup option:             myisampack.         (line   48)
* myisampack, character-sets-dir option: myisampack.         (line   53)
* myisampack, debug option:              myisampack.         (line   58)
* myisampack, force option:              myisampack.         (line   63)
* myisampack, help option:               myisampack.         (line   44)
* myisampack, join option:               myisampack.         (line   74)
* myisampack, silent option:             myisampack.         (line   89)
* myisampack, test option:               myisampack.         (line   93)
* myisampack, tmpdir option:             myisampack.         (line   97)
* myisampack, verbose option:            myisampack.         (line  102)
* myisampack, version option:            myisampack.         (line  107)
* myisampack, wait option:               myisampack.         (line  111)
* MyODBC:                                myodbc-connector.   (line   17)
* mysql:                                 programs-overview.  (line  119)
* mysql \. (command for reading from text files) <1>: batch-commands.
                                                             (line    6)
* mysql \. (command for reading from text files): batch-mode.
                                                             (line   90)
* MySQL AB, defined:                     what-is-mysql-ab.   (line    6)
* MySQL binary distribution:             which-version.      (line   19)
* MYSQL C type:                          c-api-datatypes.    (line   10)
* MySQL Cluster:                         mysql-cluster.      (line   26)
* MySQL Cluster Disk Data:               mysql-cluster-disk-data.
                                                             (line   12)
* MySQL Cluster Disk Data, creating log file groups: mysql-cluster-disk-data-objects.
                                                             (line   31)
* MySQL Cluster Disk Data, creating tables: mysql-cluster-disk-data-objects.
                                                             (line   13)
* MySQL Cluster Disk Data, creating tablespaces: mysql-cluster-disk-data-objects.
                                                             (line   84)
* MySQL Cluster Disk Data, dropping Disk Data objects: mysql-cluster-disk-data-objects.
                                                             (line  188)
* MySQL Cluster Disk Data, storage requirements: mysql-cluster-disk-data-storage-requirements.
                                                             (line    6)
* MySQL Cluster Glossary:                mysql-cluster-glossary.
                                                             (line    6)
* MySQL Cluster How-To:                  mysql-cluster-multi-computer.
                                                             (line   15)
* MySQL Cluster in MySQL 5.0 and 5.1:    mysql-cluster-roadmap.
                                                             (line   13)
* MySQL Cluster limitations:             mysql-cluster-limitations.
                                                             (line   20)
* MySQL Cluster limitations, and differences from standard MySQL limits: mysql-cluster-limitations-limits.
                                                             (line    6)
* MySQL Cluster limitations, autodiscovery: mysql-cluster-limitations-resolved.
                                                             (line   48)
* MySQL Cluster limitations, binary logging: mysql-cluster-limitations-exclusive-to-cluster.
                                                             (line   26)
* MySQL Cluster limitations, character sets: mysql-cluster-limitations-resolved.
                                                             (line   79)
* MySQL Cluster limitations, CREATE TABLE statements: mysql-cluster-limitations-resolved.
                                                             (line   92)
* MySQL Cluster limitations, database objects: mysql-cluster-limitations-database-objects.
                                                             (line    6)
* MySQL Cluster limitations, Disk Data storage: mysql-cluster-limitations-disk-data.
                                                             (line    6)
* MySQL Cluster limitations, error handling and reporting: mysql-cluster-limitations-error-handling.
                                                             (line    6)
* MySQL Cluster limitations, geometry data types: mysql-cluster-limitations-syntax.
                                                             (line   57)
* MySQL Cluster limitations, implementation: mysql-cluster-limitations-exclusive-to-cluster.
                                                             (line    6)
* MySQL Cluster limitations, imposed by configuration: mysql-cluster-limitations-limits.
                                                             (line   41)
* MySQL Cluster limitations, INSERT IGNORE, UPDATE IGNORE, and REPLACE statements: mysql-cluster-limitations-resolved.
                                                             (line   98)
* MySQL Cluster limitations, memory usage and transaction handling: mysql-cluster-limitations-transactions.
                                                             (line   40)
* MySQL Cluster limitations, multiple management servers: mysql-cluster-limitations-multiple-nodes.
                                                             (line   34)
* MySQL Cluster limitations, multiple MySQL servers: mysql-cluster-limitations-multiple-nodes.
                                                             (line    8)
* MySQL Cluster limitations, partitioning: mysql-cluster-limitations-syntax.
                                                             (line   60)
* MySQL Cluster limitations, performance: mysql-cluster-limitations-performance.
                                                             (line    6)
* MySQL Cluster limitations, replication <1>: mysql-cluster-limitations-resolved.
                                                             (line   32)
* MySQL Cluster limitations, replication: mysql-cluster-limitations-syntax.
                                                             (line   88)
* MySQL Cluster limitations, resolved in current version from previous versions: mysql-cluster-limitations-resolved.
                                                             (line    6)
* MySQL Cluster limitations, syntax:     mysql-cluster-limitations-syntax.
                                                             (line    6)
* MySQL Cluster limitations, transactions: mysql-cluster-limitations-transactions.
                                                             (line    6)
* MySQL Cluster limitations, unsupported features: mysql-cluster-limitations-unsupported-missing.
                                                             (line    6)
* MySQL Cluster processes (types):       mysql-cluster-process-management.
                                                             (line   14)
* MySQL Cluster replication <1>:         mysql-cluster-replication-two-channels.
                                                             (line    6)
* MySQL Cluster replication:             mysql-cluster-replication.
                                                             (line   19)
* MySQL Cluster replication, and -initial option: mysql-cluster-replication-issues.
                                                             (line  140)
* MySQL Cluster replication, and auto_increment* variables: mysql-cluster-replication-issues.
                                                             (line  151)
* MySQL Cluster replication, and circular replication: mysql-cluster-replication-issues.
                                                             (line   56)
* MySQL Cluster replication, and DDL:    mysql-cluster-replication-issues.
                                                             (line  124)
* MySQL Cluster replication, and multi-byte character sets: mysql-cluster-replication-issues.
                                                             (line   47)
* MySQL Cluster replication, and primary key: mysql-cluster-replication-issues.
                                                             (line  130)
* MySQL Cluster replication, backups <1>: mysql-cluster-replication-auto-sync.
                                                             (line    6)
* MySQL Cluster replication, backups:    mysql-cluster-replication-backups.
                                                             (line   10)
* MySQL Cluster replication, concepts <1>: mysql-cluster-replication-general.
                                                             (line    6)
* MySQL Cluster replication, concepts:   mysql-cluster-replication-abbreviations.
                                                             (line    6)
* MySQL Cluster replication, failover:   mysql-cluster-replication-failover.
                                                             (line    6)
* MySQL Cluster replication, known issues: mysql-cluster-replication-issues.
                                                             (line    6)
* MySQL Cluster replication, loss of connection: mysql-cluster-replication-issues.
                                                             (line   11)
* MySQL Cluster replication, preparing:  mysql-cluster-replication-preparation.
                                                             (line    6)
* MySQL Cluster replication, reset-slave.pl backup automation script: mysql-cluster-replication-auto-sync.
                                                             (line   11)
* MySQL Cluster replication, restoring from backups: mysql-cluster-replication-backups.
                                                             (line   10)
* MySQL Cluster replication, starting:   mysql-cluster-replication-starting.
                                                             (line    6)
* MySQL Cluster replication, storage engines other than NDB on slave: mysql-cluster-replication-issues.
                                                             (line  159)
* MySQL Cluster replication, system tables used: mysql-cluster-replication-schema.
                                                             (line    6)
* MySQL Cluster utilities:               mysql-cluster-utilities.
                                                             (line   25)
* MySQL Cluster, "quick" configuration:  mysql-cluster-quick.
                                                             (line    6)
* MySQL Cluster, <errortext>Table is full</errortext> error: faqs-mysql-cluster.
                                                             (line   60)
* MySQL Cluster, <foreignphrase>vs</foreignphrase> replication: faqs-mysql-cluster.
                                                             (line   19)
* MySQL Cluster, administration <1>:     mysql-cluster-log-statistics.
                                                             (line    6)
* MySQL Cluster, administration <2>:     mysql-cluster-mgm-client-commands.
                                                             (line    6)
* MySQL Cluster, administration <3>:     mysql-cluster-ndb-mgm-command-options.
                                                             (line    6)
* MySQL Cluster, administration <4>:     mysql-cluster-ndb-mgmd-command-options.
                                                             (line    6)
* MySQL Cluster, administration <5>:     mysql-cluster-ndbd-command-options.
                                                             (line    6)
* MySQL Cluster, administration <6>:     mysql-cluster-command-options.
                                                             (line   12)
* MySQL Cluster, administration:         mysql-cluster-mysqld-command-options.
                                                             (line    6)
* MySQL Cluster, and DNS:                mysql-cluster-multi-computer.
                                                             (line   46)
* MySQL Cluster, and INFORMATION_SCHEMA: mysql-cluster-security-mysql-privileges.
                                                             (line  110)
* MySQL Cluster, and IP addressing:      mysql-cluster-multi-computer.
                                                             (line   46)
* MySQL Cluster, and MySQL privileges:   mysql-cluster-security-mysql-privileges.
                                                             (line    6)
* MySQL Cluster, and MySQL root user <1>: mysql-cluster-security-mysql-security-procedures.
                                                             (line   48)
* MySQL Cluster, and MySQL root user:    mysql-cluster-security-mysql-privileges.
                                                             (line   46)
* MySQL Cluster, and networking:         mysql-cluster-multi-hardware-software-network.
                                                             (line    6)
* MySQL Cluster, and transactions:       faqs-mysql-cluster. (line   83)
* MySQL Cluster, API node <1>:           mysql-cluster-api-definition.
                                                             (line    6)
* MySQL Cluster, API node:               mysql-cluster-basics.
                                                             (line    6)
* MySQL Cluster, arbitrator:             faqs-mysql-cluster. (line  111)
* MySQL Cluster, available platforms:    mysql-cluster.      (line   65)
* MySQL Cluster, backups <1>:            mysql-cluster-backup-troubleshooting.
                                                             (line    6)
* MySQL Cluster, backups <2>:            mysql-cluster-backup-configuration.
                                                             (line    6)
* MySQL Cluster, backups <3>:            mysql-cluster-backup-using-management-client.
                                                             (line    6)
* MySQL Cluster, backups <4>:            mysql-cluster-backup-concepts.
                                                             (line    6)
* MySQL Cluster, backups:                mysql-cluster-backup.
                                                             (line   14)
* MySQL Cluster, benchmarks:             mysql-cluster-interconnects-performance.
                                                             (line    6)
* MySQL Cluster, CHECKPOINT Events:      mysql-cluster-log-events.
                                                             (line   35)
* MySQL Cluster, cluster logs <1>:       mysql-cluster-logging-management-commands.
                                                             (line    6)
* MySQL Cluster, cluster logs:           mysql-cluster-event-reports.
                                                             (line   12)
* MySQL Cluster, CLUSTERLOG commands:    mysql-cluster-logging-management-commands.
                                                             (line    8)
* MySQL Cluster, CLUSTERLOG STATISTICS command: mysql-cluster-log-statistics.
                                                             (line    6)
* MySQL Cluster, commands <1>:           mysql-cluster-mgm-client-commands.
                                                             (line    6)
* MySQL Cluster, commands <2>:           mysql-cluster-ndb-mgm-command-options.
                                                             (line    6)
* MySQL Cluster, commands <3>:           mysql-cluster-ndb-mgmd-command-options.
                                                             (line    6)
* MySQL Cluster, commands <4>:           mysql-cluster-ndbd-command-options.
                                                             (line    6)
* MySQL Cluster, commands <5>:           mysql-cluster-command-options.
                                                             (line   12)
* MySQL Cluster, commands:               mysql-cluster-mysqld-command-options.
                                                             (line    6)
* MySQL Cluster, compiling from source:  mysql-cluster-building.
                                                             (line    6)
* MySQL Cluster, compiling with icc:     porting.            (line   53)
* MySQL Cluster, concepts:               mysql-cluster-basics.
                                                             (line    6)
* MySQL Cluster, configuration <1>:      mysql-cluster-ndb-mgmd-process.
                                                             (line   26)
* MySQL Cluster, configuration <2>:      mysql-cluster-mysqld-process.
                                                             (line   32)
* MySQL Cluster, configuration <3>:      mysql-cluster-config-lcp-params.
                                                             (line    6)
* MySQL Cluster, configuration <4>:      mysql-cluster-api-definition.
                                                             (line    6)
* MySQL Cluster, configuration <5>:      mysql-cluster-ndbd-definition.
                                                             (line    6)
* MySQL Cluster, configuration <6>:      mysql-cluster-mgm-definition.
                                                             (line    6)
* MySQL Cluster, configuration <7>:      mysql-cluster-computer-definition.
                                                             (line    6)
* MySQL Cluster, configuration <8>:      mysql-cluster-quick.
                                                             (line    6)
* MySQL Cluster, configuration <9>:      mysql-cluster-configuration.
                                                             (line   15)
* MySQL Cluster, configuration:          mysql-cluster-multi-computer.
                                                             (line   15)
* MySQL Cluster, configuration (example): mysql-cluster-config-example.
                                                             (line    6)
* MySQL Cluster, configuration changes:  mysql-cluster-rolling-restart.
                                                             (line   19)
* MySQL Cluster, configuration files <1>: mysql-cluster-config-file.
                                                             (line   19)
* MySQL Cluster, configuration files:    mysql-cluster-multi-config.
                                                             (line    6)
* MySQL Cluster, configuration parameters <1>: mysql-cluster-config-params-api.
                                                             (line    6)
* MySQL Cluster, configuration parameters <2>: mysql-cluster-config-params-mgm.
                                                             (line    6)
* MySQL Cluster, configuration parameters <3>: mysql-cluster-config-params-ndbd.
                                                             (line    6)
* MySQL Cluster, configuration parameters: mysql-cluster-config-params-overview.
                                                             (line   12)
* MySQL Cluster, configuring:            mysql-cluster-backup-configuration.
                                                             (line    6)
* MySQL Cluster, CONNECTION Events:      mysql-cluster-log-events.
                                                             (line   20)
* MySQL Cluster, connectstring:          mysql-cluster-connectstring.
                                                             (line    6)
* MySQL Cluster, data node <1>:          mysql-cluster-ndbd-definition.
                                                             (line    6)
* MySQL Cluster, data node:              mysql-cluster-basics.
                                                             (line    6)
* MySQL Cluster, data types supported:   faqs-mysql-cluster. (line  115)
* MySQL Cluster, defining node hosts:    mysql-cluster-computer-definition.
                                                             (line    6)
* MySQL Cluster, direct connections between nodes: mysql-cluster-tcp-definition-direct.
                                                             (line    6)
* MySQL Cluster, Disk Data tables:       mysql-cluster-disk-data.
                                                             (line   12)
* MySQL Cluster, ENTER SINGLE USER MODE command: mysql-cluster-mgm-client-commands.
                                                             (line   99)
* MySQL Cluster, ERROR Events:           mysql-cluster-log-events.
                                                             (line  194)
* MySQL Cluster, error logs:             mysql-cluster-ndbd-process.
                                                             (line   24)
* MySQL Cluster, error messages:         faqs-mysql-cluster. (line   78)
* MySQL Cluster, event log format:       mysql-cluster-log-events.
                                                             (line    6)
* MySQL Cluster, event logging thresholds: mysql-cluster-logging-management-commands.
                                                             (line   34)
* MySQL Cluster, event logs <1>:         mysql-cluster-logging-management-commands.
                                                             (line    6)
* MySQL Cluster, event logs:             mysql-cluster-event-reports.
                                                             (line   12)
* MySQL Cluster, event severity levels:  mysql-cluster-logging-management-commands.
                                                             (line   55)
* MySQL Cluster, event types <1>:        mysql-cluster-log-events.
                                                             (line   20)
* MySQL Cluster, event types:            mysql-cluster-event-reports.
                                                             (line   49)
* MySQL Cluster, EXIT command:           mysql-cluster-mgm-client-commands.
                                                             (line  115)
* MySQL Cluster, EXIT SINGLE USER MODE command: mysql-cluster-mgm-client-commands.
                                                             (line  110)
* MySQL Cluster, FAQ:                    faqs-mysql-cluster. (line    6)
* MySQL Cluster, features new in MySQL 5.1: mysql-cluster-changes-5-1.
                                                             (line    6)
* MySQL Cluster, general description:    mysql-cluster-overview.
                                                             (line   11)
* MySQL Cluster, hardware requirements:  faqs-mysql-cluster. (line   41)
* MySQL Cluster, HELP command:           mysql-cluster-mgm-client-commands.
                                                             (line   20)
* MySQL Cluster, HostName parameter, and security: mysql-cluster-security-networking-issues.
                                                             (line   40)
* MySQL Cluster, how to obtain:          faqs-mysql-cluster. (line   10)
* MySQL Cluster, importing existing tables: faqs-mysql-cluster.
                                                             (line  105)
* MySQL Cluster, INFO Events:            mysql-cluster-log-events.
                                                             (line  208)
* MySQL Cluster, information sources:    mysql-cluster.      (line  188)
* MySQL Cluster, insecurity of communication protocols: mysql-cluster-security-networking-issues.
                                                             (line   12)
* MySQL Cluster, installation <1>:       mysql-cluster-installing.
                                                             (line    6)
* MySQL Cluster, installation <2>:       mysql-cluster-multi-install.
                                                             (line    6)
* MySQL Cluster, installation:           mysql-cluster-multi-computer.
                                                             (line   15)
* MySQL Cluster, interconnects:          mysql-cluster-interconnects.
                                                             (line   11)
* MySQL Cluster, log files:              mysql-cluster-ndbd-process.
                                                             (line   16)
* MySQL Cluster, logging commands:       mysql-cluster-logging-management-commands.
                                                             (line    6)
* MySQL Cluster, management commands:    mysql-cluster-log-statistics.
                                                             (line    6)
* MySQL Cluster, management node <1>:    mysql-cluster-mgm-definition.
                                                             (line    6)
* MySQL Cluster, management node:        mysql-cluster-basics.
                                                             (line    6)
* MySQL Cluster, managing:               mysql-cluster-management.
                                                             (line   15)
* MySQL Cluster, memory requirements:    faqs-mysql-cluster. (line   45)
* MySQL Cluster, memory usage and recovery <1>: mysql-cluster-limitations-limits.
                                                             (line    9)
* MySQL Cluster, memory usage and recovery: mysql-cluster-rolling-restart.
                                                             (line   41)
* MySQL Cluster, mgm:                    mysql-cluster-command-options.
                                                             (line   12)
* MySQL Cluster, mgm client:             mysql-cluster-mgm-client-commands.
                                                             (line    6)
* MySQL Cluster, mgm management client:  mysql-cluster-log-statistics.
                                                             (line    6)
* MySQL Cluster, mgm process:            mysql-cluster-ndb-mgm-command-options.
                                                             (line    6)
* MySQL Cluster, mgmd:                   mysql-cluster-command-options.
                                                             (line   12)
* MySQL Cluster, mgmd process:           mysql-cluster-ndb-mgmd-command-options.
                                                             (line    6)
* MySQL Cluster, mysqld process <1>:     mysql-cluster-mysqld-process.
                                                             (line    6)
* MySQL Cluster, mysqld process:         mysql-cluster-mysqld-command-options.
                                                             (line    6)
* MySQL Cluster, ndb_mgm:                mysql-cluster-multi-initial.
                                                             (line   34)
* MySQL Cluster, ndb_size.pl (utility):  faqs-mysql-cluster. (line  367)
* MySQL Cluster, ndbd:                   mysql-cluster-command-options.
                                                             (line   12)
* MySQL Cluster, ndbd process <1>:       mysql-cluster-log-statistics.
                                                             (line   32)
* MySQL Cluster, ndbd process:           mysql-cluster-ndbd-command-options.
                                                             (line    6)
* MySQL Cluster, network configuration (SCI): mysql-cluster-sci-sockets.
                                                             (line   96)
* MySQL Cluster, network configuration, and security: mysql-cluster-security-networking-issues.
                                                             (line   59)
* MySQL Cluster, network transporters <1>: mysql-cluster-sci-sockets.
                                                             (line    6)
* MySQL Cluster, network transporters:   mysql-cluster-interconnects.
                                                             (line   11)
* MySQL Cluster, networking <1>:         mysql-cluster-sci-definition.
                                                             (line    6)
* MySQL Cluster, networking <2>:         mysql-cluster-shm-definition.
                                                             (line    6)
* MySQL Cluster, networking:             mysql-cluster-tcp-definition-direct.
                                                             (line    6)
* MySQL Cluster, networking requirements: faqs-mysql-cluster.
                                                             (line   24)
* MySQL Cluster, node failure (single user mode): mysql-cluster-single-user-mode.
                                                             (line   47)
* MySQL Cluster, node identifiers <1>:   mysql-cluster-sci-definition.
                                                             (line   24)
* MySQL Cluster, node identifiers:       mysql-cluster-shm-definition.
                                                             (line   22)
* MySQL Cluster, node logs:              mysql-cluster-event-reports.
                                                             (line   12)
* MySQL Cluster, node types:             faqs-mysql-cluster. (line  243)
* MySQL Cluster, NODERESTART Events:     mysql-cluster-log-events.
                                                             (line   89)
* MySQL Cluster, nodes and node groups:  mysql-cluster-nodes-groups.
                                                             (line    6)
* MySQL Cluster, nodes and types:        mysql-cluster-basics.
                                                             (line    6)
* MySQL Cluster, number of computers required: faqs-mysql-cluster.
                                                             (line   29)
* MySQL Cluster, obtaining:              mysql-cluster-multi-install.
                                                             (line    6)
* MySQL Cluster, partitioning support:   mysql-cluster-limitations-syntax.
                                                             (line   60)
* MySQL Cluster, partitions:             mysql-cluster-nodes-groups.
                                                             (line    6)
* MySQL Cluster, performance:            mysql-cluster-interconnects-performance.
                                                             (line    6)
* MySQL Cluster, performing queries:     mysql-cluster-multi-load-data-queries.
                                                             (line    6)
* MySQL Cluster, platforms supported:    faqs-mysql-cluster. (line   37)
* MySQL Cluster, preparing for replication: mysql-cluster-replication-preparation.
                                                             (line    6)
* MySQL Cluster, process management:     mysql-cluster-process-management.
                                                             (line   14)
* MySQL Cluster, QUIT command:           mysql-cluster-mgm-client-commands.
                                                             (line  115)
* MySQL Cluster, replicas:               mysql-cluster-nodes-groups.
                                                             (line    6)
* MySQL Cluster, replication:            mysql-cluster-replication.
                                                             (line   19)
* MySQL Cluster, REPORT command:         mysql-cluster-mgm-client-commands.
                                                             (line   83)
* MySQL Cluster, requirements:           mysql-cluster-multi-hardware-software-network.
                                                             (line    6)
* MySQL Cluster, resetting:              mysql-cluster-rolling-restart.
                                                             (line   37)
* MySQL Cluster, RESTART command:        mysql-cluster-mgm-client-commands.
                                                             (line   56)
* MySQL Cluster, restarting:             mysql-cluster-multi-shutdown-restart.
                                                             (line    6)
* MySQL Cluster, roles of computers:     faqs-mysql-cluster. (line   33)
* MySQL Cluster, runtime statistics:     mysql-cluster-log-statistics.
                                                             (line    6)
* MySQL Cluster, SCI (Scalable Coherent Interface) <1>: mysql-cluster-sci-sockets.
                                                             (line    6)
* MySQL Cluster, SCI (Scalable Coherent Interface): mysql-cluster-sci-definition.
                                                             (line    6)
* MySQL Cluster, SCI drivers:            mysql-cluster-sci-sockets.
                                                             (line  198)
* MySQL Cluster, SCI network configuration: mysql-cluster-sci-sockets.
                                                             (line   96)
* MySQL Cluster, SCI software installation: mysql-cluster-sci-sockets.
                                                             (line   63)
* MySQL Cluster, SCI software requirements: mysql-cluster-sci-sockets.
                                                             (line   32)
* MySQL Cluster, security <1>:           faqs-mysql-cluster. (line  453)
* MySQL Cluster, security:               mysql-cluster-security.
                                                             (line   12)
* MySQL Cluster, security procedures:    mysql-cluster-security-mysql-security-procedures.
                                                             (line    6)
* MySQL Cluster, security, and firewalls: mysql-cluster-security-networking-issues.
                                                             (line   98)
* MySQL Cluster, security, and HostName parameter: mysql-cluster-security-networking-issues.
                                                             (line   40)
* MySQL Cluster, security, and network configuration: mysql-cluster-security-networking-issues.
                                                             (line   59)
* MySQL Cluster, security, and network ports: mysql-cluster-security-networking-issues.
                                                             (line  182)
* MySQL Cluster, security, and remote administration: mysql-cluster-security-networking-issues.
                                                             (line  189)
* MySQL Cluster, security, networking:   mysql-cluster-security-networking-issues.
                                                             (line    6)
* MySQL Cluster, shared memory transport: mysql-cluster-shm-definition.
                                                             (line    6)
* MySQL Cluster, SHOW command:           mysql-cluster-mgm-client-commands.
                                                             (line   24)
* MySQL Cluster, SHUTDOWN command:       mysql-cluster-mgm-client-commands.
                                                             (line  121)
* MySQL Cluster, shutting down:          mysql-cluster-multi-shutdown-restart.
                                                             (line    6)
* MySQL Cluster, single user mode <1>:   mysql-cluster-single-user-mode.
                                                             (line    6)
* MySQL Cluster, single user mode:       mysql-cluster-mgm-client-commands.
                                                             (line   99)
* MySQL Cluster, SQL node <1>:           mysql-cluster-api-definition.
                                                             (line    6)
* MySQL Cluster, SQL node:               mysql-cluster-basics.
                                                             (line    6)
* MySQL Cluster, SQL nodes:              mysql-cluster-mysqld-process.
                                                             (line    6)
* MySQL Cluster, SQL statements:         faqs-mysql-cluster. (line   73)
* MySQL Cluster, SQL statements for monitoring: mysql-cluster-sql-statements.
                                                             (line    6)
* MySQL Cluster, START BACKUP command:   mysql-cluster-replication-backups.
                                                             (line   38)
* MySQL Cluster, START command:          mysql-cluster-mgm-client-commands.
                                                             (line   34)
* MySQL Cluster, start phases (summary): mysql-cluster-start-phases.
                                                             (line    6)
* MySQL Cluster, starting:               mysql-cluster-quick.
                                                             (line    6)
* MySQL Cluster, starting and stopping:  faqs-mysql-cluster. (line  119)
* MySQL Cluster, starting nodes:         mysql-cluster-multi-initial.
                                                             (line    6)
* MySQL Cluster, starting or restarting: mysql-cluster-start-phases.
                                                             (line    6)
* MySQL Cluster, STARTUP Events:         mysql-cluster-log-events.
                                                             (line   54)
* MySQL Cluster, STATISTICS Events:      mysql-cluster-log-events.
                                                             (line  170)
* MySQL Cluster, STATUS command:         mysql-cluster-mgm-client-commands.
                                                             (line   78)
* MySQL Cluster, STOP command:           mysql-cluster-mgm-client-commands.
                                                             (line   47)
* MySQL Cluster, storage requirements:   storage-requirements.
                                                             (line   13)
* MySQL Cluster, terminology:            mysql-cluster-glossary.
                                                             (line    6)
* MySQL Cluster, thread states:          mysql-cluster-thread-states.
                                                             (line    6)
* MySQL Cluster, trace files:            mysql-cluster-ndbd-process.
                                                             (line   55)
* MySQL Cluster, transaction handling:   mysql-cluster-limitations-transactions.
                                                             (line   40)
* MySQL Cluster, transactions:           mysql-cluster-ndbd-definition.
                                                             (line  230)
* MySQL Cluster, transporters, Scalable Coherent Interface (SCI): mysql-cluster-sci-definition.
                                                             (line    6)
* MySQL Cluster, transporters, shared memory (SHM): mysql-cluster-shm-definition.
                                                             (line    6)
* MySQL Cluster, transporters, TCP/IP:   mysql-cluster-tcp-definition-direct.
                                                             (line    6)
* MySQL Cluster, troubleshooting backups: mysql-cluster-backup-troubleshooting.
                                                             (line    6)
* MySQL Cluster, upgrades and downgrades <1>: mysql-cluster-upgrade-downgrade-compatibility.
                                                             (line    6)
* MySQL Cluster, upgrades and downgrades <2>: mysql-cluster-rolling-restart.
                                                             (line    6)
* MySQL Cluster, upgrades and downgrades: mysql-cluster-upgrade-downgrade.
                                                             (line   11)
* MySQL Cluster, using in a virtual machine: faqs-mysql-cluster.
                                                             (line   53)
* MySQL Cluster, using tables and data:  mysql-cluster-multi-load-data-queries.
                                                             (line    6)
* mysql command options:                 mysql-command-options.
                                                             (line    6)
* mysql commands, list of:               mysql-commands.     (line   11)
* MySQL Dolphin name:                    history.            (line    6)
* MySQL history:                         history.            (line    6)
* mysql history file:                    mysql-command-options.
                                                             (line  566)
* MySQL mailing lists:                   mailing-lists.      (line   10)
* MySQL name:                            history.            (line    6)
* MySQL privileges, and MySQL Cluster:   mysql-cluster-security-mysql-privileges.
                                                             (line   10)
* mysql prompt command:                  mysql-commands.     (line  274)
* MySQL server, mysqld:                  mysqld-server.      (line   19)
* mysql source (command for reading from text files) <1>: batch-commands.
                                                             (line    6)
* mysql source (command for reading from text files): batch-mode.
                                                             (line   90)
* MySQL source distribution:             which-version.      (line   19)
* MySQL storage engines:                 storage-engines.    (line   21)
* MySQL system tables, and MySQL Cluster: mysql-cluster-security-mysql-privileges.
                                                             (line   22)
* MySQL version:                         getting-mysql.      (line    6)
* MySQL++:                               cplusplus.          (line    6)
* mysql, auto-rehash option:             mysql-command-options.
                                                             (line  130)
* mysql, batch option:                   mysql-command-options.
                                                             (line  144)
* mysql, character-sets-dir option:      mysql-command-options.
                                                             (line  154)
* mysql, charset command:                mysql-commands.     (line   61)
* mysql, clear command:                  mysql-commands.     (line   70)
* mysql, column-names option:            mysql-command-options.
                                                             (line  159)
* mysql, column-type-info option:        mysql-command-options.
                                                             (line  163)
* mysql, comments option:                mysql-command-options.
                                                             (line  169)
* mysql, compress option:                mysql-command-options.
                                                             (line  176)
* mysql, connect command:                mysql-commands.     (line   75)
* mysql, database option:                mysql-command-options.
                                                             (line  181)
* mysql, debug option:                   mysql-command-options.
                                                             (line  185)
* mysql, debug-check option:             mysql-command-options.
                                                             (line  190)
* mysql, debug-info option:              mysql-command-options.
                                                             (line  195)
* mysql, default-character-set option:   mysql-command-options.
                                                             (line  203)
* MySQL, defined:                        what-is-mysql.      (line    6)
* mysql, delimiter command:              mysql-commands.     (line   82)
* mysql, delimiter option:               mysql-command-options.
                                                             (line  208)
* mysql, disable named commands:         mysql-command-options.
                                                             (line  213)
* mysql, edit command:                   mysql-commands.     (line  100)
* mysql, ego command:                    mysql-commands.     (line  109)
* mysql, execute option:                 mysql-command-options.
                                                             (line  221)
* mysql, exit command:                   mysql-commands.     (line  114)
* mysql, force option:                   mysql-command-options.
                                                             (line  227)
* mysql, go command:                     mysql-commands.     (line  118)
* mysql, help command:                   mysql-commands.     (line   52)
* mysql, help option:                    mysql-command-options.
                                                             (line  126)
* mysql, host option:                    mysql-command-options.
                                                             (line  231)
* mysql, html option:                    mysql-command-options.
                                                             (line  235)
* mysql, i-am-a-dummy option:            mysql-command-options.
                                                             (line  388)
* mysql, ignore-spaces option:           mysql-command-options.
                                                             (line  239)
* MySQL, introduction:                   what-is-mysql.      (line    6)
* mysql, line-numbers option:            mysql-command-options.
                                                             (line  245)
* mysql, local-infile option:            mysql-command-options.
                                                             (line  250)
* mysql, named-commands option:          mysql-command-options.
                                                             (line  265)
* mysql, no-auto-rehash option:          mysql-command-options.
                                                             (line  272)
* mysql, no-beep option:                 mysql-command-options.
                                                             (line  278)
* mysql, no-named-commands option:       mysql-command-options.
                                                             (line  282)
* mysql, no-pager option:                mysql-command-options.
                                                             (line  286)
* mysql, no-tee option:                  mysql-command-options.
                                                             (line  290)
* mysql, nopager command:                mysql-commands.     (line  122)
* mysql, notee command:                  mysql-commands.     (line  128)
* mysql, nowarning command:              mysql-commands.     (line  133)
* mysql, one-database option:            mysql-command-options.
                                                             (line  295)
* mysql, pager command:                  mysql-commands.     (line  137)
* mysql, pager option:                   mysql-command-options.
                                                             (line  301)
* mysql, password option:                mysql-command-options.
                                                             (line  310)
* mysql, pipe option:                    mysql-command-options.
                                                             (line  321)
* mysql, port option:                    mysql-command-options.
                                                             (line  327)
* mysql, print command:                  mysql-commands.     (line  158)
* mysql, prompt command:                 mysql-commands.     (line  162)
* mysql, prompt option:                  mysql-command-options.
                                                             (line  331)
* MySQL, pronunciation:                  what-is-mysql.      (line   87)
* mysql, protocol option:                mysql-command-options.
                                                             (line  337)
* mysql, quick option:                   mysql-command-options.
                                                             (line  344)
* mysql, quit command:                   mysql-commands.     (line  171)
* mysql, raw option:                     mysql-command-options.
                                                             (line  350)
* mysql, reconnect option:               mysql-command-options.
                                                             (line  381)
* mysql, rehash command:                 mysql-commands.     (line  175)
* mysql, safe-updates option:            mysql-command-options.
                                                             (line  388)
* mysql, secure-auth option:             mysql-command-options.
                                                             (line  396)
* mysql, show-warnings option:           mysql-command-options.
                                                             (line  408)
* mysql, sigint-ignore option:           mysql-command-options.
                                                             (line  413)
* mysql, silent option:                  mysql-command-options.
                                                             (line  417)
* mysql, skip-column-names option:       mysql-command-options.
                                                             (line  426)
* mysql, skip-line-numbers option:       mysql-command-options.
                                                             (line  431)
* mysql, socket option:                  mysql-command-options.
                                                             (line  437)
* mysql, source command:                 mysql-commands.     (line  181)
* mysql, SSL options:                    mysql-command-options.
                                                             (line  442)
* mysql, status command:                 mysql-commands.     (line  187)
* mysql, system command:                 mysql-commands.     (line  194)
* mysql, table option:                   mysql-command-options.
                                                             (line  448)
* mysql, tee command:                    mysql-commands.     (line  200)
* mysql, tee option:                     mysql-command-options.
                                                             (line  454)
* mysql, unbuffered option:              mysql-command-options.
                                                             (line  460)
* mysql, use command:                    mysql-commands.     (line  213)
* mysql, user option:                    mysql-command-options.
                                                             (line  464)
* mysql, verbose option:                 mysql-command-options.
                                                             (line  468)
* mysql, version option:                 mysql-command-options.
                                                             (line  475)
* mysql, vertical option:                mysql-command-options.
                                                             (line  479)
* mysql, wait option:                    mysql-command-options.
                                                             (line  485)
* mysql, warnings command:               mysql-commands.     (line  217)
* mysql, xml option:                     mysql-command-options.
                                                             (line  490)
* mysql.event table:                     events-privileges.  (line  144)
* mysql.ndb_binlog_index table:          mysql-cluster-replication-schema.
                                                             (line    6)
* mysql.server:                          programs-overview.  (line   47)
* mysql.server, basedir option:          mysql-server.       (line   34)
* mysql.server, datadir option:          mysql-server.       (line   38)
* mysql.server, pid-file option:         mysql-server.       (line   42)
* mysql.server, service-startup-timeout option: mysql-server.
                                                             (line   47)
* mysql.server, use-manager option:      mysql-server.       (line   60)
* mysql.server, use-mysqld_safe option:  mysql-server.       (line   56)
* mysql.server, user option:             mysql-server.       (line   64)
* mysql.sock, changing location of:      configure-options.  (line  329)
* mysql.sock, protection:                problems-with-mysql-sock.
                                                             (line    6)
* MYSQL323 SQL mode:                     server-sql-mode.    (line  472)
* MYSQL40 SQL mode:                      server-sql-mode.    (line  476)
* mysql_affected_rows():                 mysql-affected-rows.
                                                             (line    6)
* mysql_autocommit():                    mysql-autocommit.   (line    6)
* MYSQL_BIND C type:                     c-api-prepared-statement-datatypes.
                                                             (line   43)
* mysql_change_user():                   mysql-change-user.  (line    6)
* mysql_character_set_name():            mysql-character-set-name.
                                                             (line    6)
* mysql_close():                         mysql-close.        (line    6)
* mysql_commit():                        mysql-commit.       (line    6)
* mysql_connect():                       mysql-connect.      (line    6)
* mysql_convert_table_format:            programs-overview.  (line  211)
* mysql_create_db():                     mysql-create-db.    (line    6)
* mysql_data_seek():                     mysql-data-seek.    (line    6)
* MYSQL_DEBUG environment variable <1>:  debugging-client.   (line   10)
* MYSQL_DEBUG environment variable <2>:  programs-overview.  (line  303)
* MYSQL_DEBUG environment variable:      environment-variables.
                                                             (line   18)
* mysql_debug():                         mysql-debug.        (line    6)
* mysql_drop_db():                       mysql-drop-db.      (line    6)
* mysql_dump_debug_info():               mysql-dump-debug-info.
                                                             (line    6)
* mysql_eof():                           mysql-eof.          (line    6)
* mysql_errno():                         mysql-errno.        (line    6)
* mysql_error():                         mysql-error.        (line    6)
* mysql_escape_string():                 mysql-escape-string.
                                                             (line    6)
* mysql_explain_log, help option:        mysql-convert-table-format.
                                                             (line   25)
* mysql_explain_log, host option:        mysql-convert-table-format.
                                                             (line   33)
* mysql_explain_log, password option:    mysql-convert-table-format.
                                                             (line   37)
* mysql_explain_log, socket option:      mysql-convert-table-format.
                                                             (line   51)
* mysql_explain_log, user option:        mysql-convert-table-format.
                                                             (line   66)
* mysql_fetch_field():                   mysql-fetch-field.  (line    6)
* mysql_fetch_field_direct():            mysql-fetch-field-direct.
                                                             (line    6)
* mysql_fetch_fields():                  mysql-fetch-fields. (line    6)
* mysql_fetch_lengths():                 mysql-fetch-lengths.
                                                             (line    6)
* mysql_fetch_row():                     mysql-fetch-row.    (line    6)
* MYSQL_FIELD C type:                    c-api-datatypes.    (line   33)
* mysql_field_count() <1>:               mysql-num-fields.   (line    6)
* mysql_field_count():                   mysql-field-count.  (line    6)
* MYSQL_FIELD_OFFSET C type:             c-api-datatypes.    (line   42)
* mysql_field_seek():                    mysql-field-seek.   (line    6)
* mysql_field_tell():                    mysql-field-tell.   (line    6)
* mysql_find_rows:                       programs-overview.  (line  216)
* mysql_find_rows, help option:          mysql-find-rows.    (line   27)
* mysql_find_rows, regexp option:        mysql-find-rows.    (line   31)
* mysql_find_rows, rows option:          mysql-find-rows.    (line   35)
* mysql_find_rows, skip-use-db option:   mysql-find-rows.    (line   39)
* mysql_find_rows, start_row option:     mysql-find-rows.    (line   43)
* mysql_fix_extensions:                  programs-overview.  (line  222)
* mysql_fix_privilege_tables:            programs-overview.  (line   82)
* mysql_free_result():                   mysql-free-result.  (line    6)
* mysql_get_character_set_info():        mysql-get-character-set-info.
                                                             (line    6)
* mysql_get_client_info():               mysql-get-client-info.
                                                             (line    6)
* mysql_get_client_version():            mysql-get-client-version.
                                                             (line    6)
* mysql_get_host_info():                 mysql-get-host-info.
                                                             (line    6)
* mysql_get_proto_info():                mysql-get-proto-info.
                                                             (line    6)
* mysql_get_server_info():               mysql-get-server-info.
                                                             (line    6)
* mysql_get_server_version():            mysql-get-server-version.
                                                             (line    6)
* mysql_get_ssl_cipher():                mysql-get-ssl-cipher.
                                                             (line    6)
* MYSQL_GROUP_SUFFIX environment variable: environment-variables.
                                                             (line   18)
* mysql_hex_string():                    mysql-hex-string.   (line    6)
* MYSQL_HISTFILE environment variable <1>: mysql-command-options.
                                                             (line  566)
* MYSQL_HISTFILE environment variable:   environment-variables.
                                                             (line   18)
* MYSQL_HOME environment variable:       environment-variables.
                                                             (line   18)
* MYSQL_HOST environment variable <1>:   connecting.         (line  209)
* MYSQL_HOST environment variable:       environment-variables.
                                                             (line   18)
* mysql_info() <1>:                      mysql-info.         (line    6)
* mysql_info() <2>:                      update.             (line   69)
* mysql_info() <3>:                      load-data.          (line  626)
* mysql_info() <4>:                      insert.             (line  193)
* mysql_info():                          alter-table.        (line  772)
* mysql_init():                          mysql-init.         (line    6)
* mysql_insert_id() <1>:                 mysql-insert-id.    (line    6)
* mysql_insert_id() <2>:                 insert.             (line  197)
* mysql_insert_id():                     ansi-diff-transactions.
                                                             (line  160)
* mysql_install_db:                      programs-overview.  (line   91)
* mysql_install_db script:               mysql-install-db-problems.
                                                             (line    6)
* mysql_kill():                          mysql-kill.         (line    6)
* mysql_library_end():                   mysql-library-end.  (line    6)
* mysql_library_init():                  mysql-library-init. (line    6)
* mysql_list_dbs():                      mysql-list-dbs.     (line    6)
* mysql_list_fields():                   mysql-list-fields.  (line    6)
* mysql_list_processes():                mysql-list-processes.
                                                             (line    6)
* mysql_list_tables():                   mysql-list-tables.  (line    6)
* mysql_more_results():                  mysql-more-results. (line    6)
* mysql_next_result():                   mysql-next-result.  (line    6)
* mysql_num_fields():                    mysql-num-fields.   (line    6)
* mysql_num_rows():                      mysql-num-rows.     (line    6)
* mysql_options():                       mysql-options.      (line    6)
* mysql_ping():                          mysql-ping.         (line    6)
* MYSQL_PS1 environment variable:        environment-variables.
                                                             (line   18)
* MYSQL_PWD environment variable <1>:    connecting.         (line  209)
* MYSQL_PWD environment variable <2>:    programs-overview.  (line  303)
* MYSQL_PWD environment variable:        environment-variables.
                                                             (line   18)
* mysql_query() <1>:                     c-api-problems.     (line   13)
* mysql_query():                         mysql-query.        (line    6)
* mysql_real_connect():                  mysql-real-connect. (line    6)
* mysql_real_escape_string() <1>:        mysql-real-escape-string.
                                                             (line    6)
* mysql_real_escape_string():            string-syntax.      (line  133)
* mysql_real_query():                    mysql-real-query.   (line    6)
* mysql_refresh():                       mysql-refresh.      (line    6)
* mysql_reload():                        mysql-reload.       (line    6)
* MYSQL_RES C type:                      c-api-datatypes.    (line   17)
* mysql_rollback():                      mysql-rollback.     (line    6)
* MYSQL_ROW C type:                      c-api-datatypes.    (line   24)
* mysql_row_seek():                      mysql-row-seek.     (line    6)
* mysql_row_tell():                      mysql-row-tell.     (line    6)
* mysql_secure_installation:             programs-overview.  (line   98)
* mysql_select_db():                     mysql-select-db.    (line    6)
* mysql_server_end():                    mysql-server-end.   (line    6)
* mysql_server_init():                   mysql-server-init.  (line    6)
* mysql_set_character_set():             mysql-set-character-set.
                                                             (line    6)
* mysql_set_local_infile_default():      mysql-set-local-infile-default.
                                                             (line    6)
* mysql_set_server_option():             mysql-set-server-option.
                                                             (line    6)
* mysql_setpermission:                   programs-overview.  (line  229)
* mysql_setpermission, help option:      mysql-setpermission.
                                                             (line   27)
* mysql_setpermission, host option:      mysql-setpermission.
                                                             (line   31)
* mysql_setpermission, password option:  mysql-setpermission.
                                                             (line   35)
* mysql_setpermission, port option:      mysql-setpermission.
                                                             (line   45)
* mysql_setpermission, socket option:    mysql-setpermission.
                                                             (line   49)
* mysql_setpermission, user option:      mysql-setpermission.
                                                             (line   53)
* mysql_shutdown():                      mysql-shutdown.     (line    6)
* mysql_sqlstate():                      mysql-sqlstate.     (line    6)
* mysql_ssl_set():                       mysql-ssl-set.      (line    6)
* mysql_stat():                          mysql-stat.         (line    6)
* MYSQL_STMT C type:                     c-api-prepared-statement-datatypes.
                                                             (line   24)
* mysql_stmt_affected_rows():            mysql-stmt-affected-rows.
                                                             (line    6)
* mysql_stmt_attr_get():                 mysql-stmt-attr-get.
                                                             (line    6)
* mysql_stmt_attr_set():                 mysql-stmt-attr-set.
                                                             (line    6)
* mysql_stmt_bind_param():               mysql-stmt-bind-param.
                                                             (line    6)
* mysql_stmt_bind_result():              mysql-stmt-bind-result.
                                                             (line    6)
* mysql_stmt_close():                    mysql-stmt-close.   (line    6)
* mysql_stmt_data_seek():                mysql-stmt-data-seek.
                                                             (line    6)
* mysql_stmt_errno():                    mysql-stmt-errno.   (line    6)
* mysql_stmt_error():                    mysql-stmt-error.   (line    6)
* mysql_stmt_execute():                  mysql-stmt-execute. (line    6)
* mysql_stmt_fetch():                    mysql-stmt-fetch.   (line    6)
* mysql_stmt_fetch_column():             mysql-stmt-fetch-column.
                                                             (line    6)
* mysql_stmt_field_count():              mysql-stmt-field-count.
                                                             (line    6)
* mysql_stmt_free_result():              mysql-stmt-free-result.
                                                             (line    6)
* mysql_stmt_init():                     mysql-stmt-init.    (line    6)
* mysql_stmt_insert_id():                mysql-stmt-insert-id.
                                                             (line    6)
* mysql_stmt_num_rows():                 mysql-stmt-num-rows.
                                                             (line    6)
* mysql_stmt_param_count():              mysql-stmt-param-count.
                                                             (line    6)
* mysql_stmt_param_metadata():           mysql-stmt-param-metadata.
                                                             (line    6)
* mysql_stmt_prepare():                  mysql-stmt-prepare. (line    6)
* mysql_stmt_reset():                    mysql-stmt-reset.   (line    6)
* mysql_stmt_result_metadata:            mysql-stmt-result-metadata.
                                                             (line    6)
* mysql_stmt_row_seek():                 mysql-stmt-row-seek.
                                                             (line    6)
* mysql_stmt_row_tell():                 mysql-stmt-row-tell.
                                                             (line    6)
* mysql_stmt_send_long_data():           mysql-stmt-send-long-data.
                                                             (line    6)
* mysql_stmt_sqlstate():                 mysql-stmt-sqlstate.
                                                             (line    6)
* mysql_stmt_store_result():             mysql-stmt-store-result.
                                                             (line    6)
* mysql_store_result() <1>:              c-api-problems.     (line   13)
* mysql_store_result():                  mysql-store-result. (line    6)
* MYSQL_TCP_PORT environment variable <1>: multiple-server-clients.
                                                             (line   27)
* MYSQL_TCP_PORT environment variable <2>: multiple-unix-servers.
                                                             (line   58)
* MYSQL_TCP_PORT environment variable <3>: programs-overview.
                                                             (line  303)
* MYSQL_TCP_PORT environment variable:   environment-variables.
                                                             (line   18)
* mysql_thread_end():                    mysql-thread-end.   (line    6)
* mysql_thread_id():                     mysql-thread-id.    (line    6)
* mysql_thread_init():                   mysql-thread-init.  (line    6)
* mysql_thread_safe():                   mysql-thread-safe.  (line    6)
* MYSQL_TIME C type:                     c-api-prepared-statement-datatypes.
                                                             (line  229)
* mysql_tzinfo_to_sql:                   programs-overview.  (line  103)
* MYSQL_UNIX_PORT environment variable <1>: multiple-server-clients.
                                                             (line   27)
* MYSQL_UNIX_PORT environment variable <2>: multiple-unix-servers.
                                                             (line   58)
* MYSQL_UNIX_PORT environment variable <3>: programs-overview.
                                                             (line  303)
* MYSQL_UNIX_PORT environment variable <4>: environment-variables.
                                                             (line   18)
* MYSQL_UNIX_PORT environment variable:  mysql-install-db-problems.
                                                             (line   76)
* mysql_upgrade <1>:                     access-denied.      (line   72)
* mysql_upgrade:                         programs-overview.  (line  110)
* mysql_upgrade, basedir option:         mysql-upgrade.      (line   73)
* mysql_upgrade, datadir option:         mysql-upgrade.      (line   77)
* mysql_upgrade, debug-check option:     mysql-upgrade.      (line   81)
* mysql_upgrade, debug-info option:      mysql-upgrade.      (line   86)
* mysql_upgrade, force option:           mysql-upgrade.      (line   91)
* mysql_upgrade, help option:            mysql-upgrade.      (line   69)
* mysql_upgrade, tmpdir option:          mysql-upgrade.      (line   98)
* mysql_upgrade, user option:            mysql-upgrade.      (line  103)
* mysql_upgrade, verbose option:         mysql-upgrade.      (line  108)
* mysql_use_result():                    mysql-use-result.   (line    6)
* mysql_waitpid:                         programs-overview.  (line  234)
* mysql_waitpid, help option:            mysql-waitpid.      (line   26)
* mysql_waitpid, verbose option:         mysql-waitpid.      (line   30)
* mysql_waitpid, version option:         mysql-waitpid.      (line   35)
* mysql_warning_count():                 mysql-warning-count.
                                                             (line    6)
* mysql_zap:                             programs-overview.  (line  239)
* mysqlaccess:                           programs-overview.  (line  185)
* mysqlaccess, brief option:             mysqlaccess.        (line   63)
* mysqlaccess, commit option:            mysqlaccess.        (line   67)
* mysqlaccess, copy option:              mysqlaccess.        (line   74)
* mysqlaccess, db option:                mysqlaccess.        (line   78)
* mysqlaccess, debug option:             mysqlaccess.        (line   82)
* mysqlaccess, help option:              mysqlaccess.        (line   59)
* mysqlaccess, host option:              mysqlaccess.        (line   86)
* mysqlaccess, howto option:             mysqlaccess.        (line   90)
* mysqlaccess, old_server option:        mysqlaccess.        (line   94)
* mysqlaccess, password option:          mysqlaccess.        (line   99)
* mysqlaccess, plan option:              mysqlaccess.        (line  108)
* mysqlaccess, preview option:           mysqlaccess.        (line  112)
* mysqlaccess, relnotes option:          mysqlaccess.        (line  117)
* mysqlaccess, rhost option:             mysqlaccess.        (line  121)
* mysqlaccess, rollback option:          mysqlaccess.        (line  125)
* mysqlaccess, spassword option:         mysqlaccess.        (line  129)
* mysqlaccess, superuser option:         mysqlaccess.        (line  139)
* mysqlaccess, table option:             mysqlaccess.        (line  143)
* mysqlaccess, user option:              mysqlaccess.        (line  147)
* mysqlaccess, version option:           mysqlaccess.        (line  151)
* mysqladmin <1>:                        kill.               (line    6)
* mysqladmin <2>:                        flush.              (line    6)
* mysqladmin <3>:                        show-variables.     (line    9)
* mysqladmin <4>:                        show-status.        (line    9)
* mysqladmin <5>:                        drop-database.      (line   45)
* mysqladmin <6>:                        create-database.    (line   40)
* mysqladmin:                            programs-overview.  (line  124)
* mysqladmin command options:            mysqladmin.         (line  226)
* mysqladmin option, mysqld_multi:       mysqld-multi.       (line  106)
* mysqladmin, character-sets-dir option: mysqladmin.         (line  298)
* mysqladmin, compress option:           mysqladmin.         (line  303)
* mysqladmin, count option:              mysqladmin.         (line  308)
* mysqladmin, debug option:              mysqladmin.         (line  313)
* mysqladmin, debug-check option:        mysqladmin.         (line   28)
* mysqladmin, debug-info option:         mysqladmin.         (line   33)
* mysqladmin, default-character-set option: mysqladmin.      (line  319)
* mysqladmin, force option:              mysqladmin.         (line  324)
* mysqladmin, help option:               mysqladmin.         (line  294)
* mysqladmin, host option:               mysqladmin.         (line  329)
* mysqladmin, no-beep option:            mysqladmin.         (line  333)
* mysqladmin, password option:           mysqladmin.         (line  339)
* mysqladmin, pipe option:               mysqladmin.         (line  350)
* mysqladmin, port option:               mysqladmin.         (line  356)
* mysqladmin, protocol option:           mysqladmin.         (line  360)
* mysqladmin, relative option:           mysqladmin.         (line  367)
* mysqladmin, silent option:             mysqladmin.         (line  373)
* mysqladmin, sleep option:              mysqladmin.         (line  377)
* mysqladmin, socket option:             mysqladmin.         (line  384)
* mysqladmin, SSL options:               mysqladmin.         (line  389)
* mysqladmin, user option:               mysqladmin.         (line  395)
* mysqladmin, verbose option:            mysqladmin.         (line  399)
* mysqladmin, version option:            mysqladmin.         (line  403)
* mysqladmin, vertical option:           mysqladmin.         (line  407)
* mysqladmin, wait option:               mysqladmin.         (line  412)
* mysqlbinlog:                           programs-overview.  (line  190)
* mysqlbinlog, base64-output option:     mysqlbinlog.        (line  115)
* mysqlbinlog, character-sets-dir option: mysqlbinlog.       (line  122)
* mysqlbinlog, database option:          mysqlbinlog.        (line  127)
* mysqlbinlog, debug option:             mysqlbinlog.        (line  138)
* mysqlbinlog, debug-check option:       mysqlbinlog.        (line  143)
* mysqlbinlog, debug-info option:        mysqlbinlog.        (line  148)
* mysqlbinlog, disable-log-bin option:   mysqlbinlog.        (line  153)
* mysqlbinlog, force-read option:        mysqlbinlog.        (line  167)
* mysqlbinlog, help option:              mysqlbinlog.        (line  111)
* mysqlbinlog, hexdump option:           mysqlbinlog.        (line  174)
* mysqlbinlog, host option:              mysqlbinlog.        (line  180)
* mysqlbinlog, local-load option:        mysqlbinlog.        (line  184)
* mysqlbinlog, offset option:            mysqlbinlog.        (line  189)
* mysqlbinlog, password option:          mysqlbinlog.        (line  193)
* mysqlbinlog, port option:              mysqlbinlog.        (line  204)
* mysqlbinlog, position option:          mysqlbinlog.        (line  208)
* mysqlbinlog, protocol option:          mysqlbinlog.        (line  212)
* mysqlbinlog, read-from-remote-server option: mysqlbinlog.  (line  219)
* mysqlbinlog, result-file option:       mysqlbinlog.        (line  230)
* mysqlbinlog, server-id option:         mysqlbinlog.        (line  234)
* mysqlbinlog, set-charset option:       mysqlbinlog.        (line  239)
* mysqlbinlog, short-form option:        mysqlbinlog.        (line  245)
* mysqlbinlog, socket option:            mysqlbinlog.        (line  250)
* mysqlbinlog, start-datetime option:    mysqlbinlog.        (line  255)
* mysqlbinlog, start-position option:    mysqlbinlog.        (line  275)
* mysqlbinlog, stop-datetime option:     mysqlbinlog.        (line  268)
* mysqlbinlog, stop-position option:     mysqlbinlog.        (line  281)
* mysqlbinlog, to-last-log option:       mysqlbinlog.        (line  287)
* mysqlbinlog, user option:              mysqlbinlog.        (line  295)
* mysqlbinlog, version option:           mysqlbinlog.        (line  299)
* mysqlbug script:                       bug-reports.        (line  328)
* mysqlcheck:                            programs-overview.  (line  132)
* mysqlcheck, all-databases option:      mysqlcheck.         (line  157)
* mysqlcheck, all-in-1 option:           mysqlcheck.         (line  163)
* mysqlcheck, analyze option:            mysqlcheck.         (line  169)
* mysqlcheck, auto-repair option:        mysqlcheck.         (line  179)
* mysqlcheck, character-sets-dir option: mysqlcheck.         (line  184)
* mysqlcheck, check option:              mysqlcheck.         (line  189)
* mysqlcheck, check-only-changed option: mysqlcheck.         (line  193)
* mysqlcheck, check-upgrade option:      mysqlcheck.         (line  198)
* mysqlcheck, compress option:           mysqlcheck.         (line  206)
* mysqlcheck, databases option:          mysqlcheck.         (line  211)
* mysqlcheck, debug option:              mysqlcheck.         (line  218)
* mysqlcheck, debug-check option:        mysqlcheck.         (line  223)
* mysqlcheck, debug-info option:         mysqlcheck.         (line  228)
* mysqlcheck, default-character-set option: mysqlcheck.      (line  233)
* mysqlcheck, extended option:           mysqlcheck.         (line  238)
* mysqlcheck, fast option:               mysqlcheck.         (line  247)
* mysqlcheck, fix-db-names option:       mysqlcheck.         (line  251)
* mysqlcheck, fix-table-names option:    mysqlcheck.         (line  257)
* mysqlcheck, force option:              mysqlcheck.         (line  263)
* mysqlcheck, help option:               mysqlcheck.         (line  153)
* mysqlcheck, host option:               mysqlcheck.         (line  267)
* mysqlcheck, medium-check option:       mysqlcheck.         (line  271)
* mysqlcheck, optimize option:           mysqlcheck.         (line  277)
* mysqlcheck, password option:           mysqlcheck.         (line  281)
* mysqlcheck, pipe option:               mysqlcheck.         (line  292)
* mysqlcheck, port option:               mysqlcheck.         (line  298)
* mysqlcheck, protocol option:           mysqlcheck.         (line  302)
* mysqlcheck, quick option:              mysqlcheck.         (line  309)
* mysqlcheck, repair option:             mysqlcheck.         (line  318)
* mysqlcheck, silent option:             mysqlcheck.         (line  323)
* mysqlcheck, socket option:             mysqlcheck.         (line  327)
* mysqlcheck, SSL options:               mysqlcheck.         (line  332)
* mysqlcheck, tables option:             mysqlcheck.         (line  338)
* mysqlcheck, use-frm option:            mysqlcheck.         (line  343)
* mysqlcheck, user option:               mysqlcheck.         (line  349)
* mysqlcheck, verbose option:            mysqlcheck.         (line  353)
* mysqlcheck, version option:            mysqlcheck.         (line  358)
* mysqlcheck, write-binlog option:       mysqlbinlog.        (line  303)
* mysqlclient library:                   apis.               (line   17)
* mysqld:                                programs-overview.  (line   36)
* mysqld library:                        apis.               (line   17)
* mysqld option, mysqld_multi:           mysqld-multi.       (line  110)
* mysqld option, mysqld_safe:            mysqld-safe.        (line  157)
* mysqld options:                        server-parameters.  (line   11)
* mysqld server, buffer sizes:           server-parameters.  (line    6)
* mysqld, abort-slave-event-count option: server-options.    (line   54)
* mysqld, allow-suspicious-udfs option <1>: privileges-options.
                                                             (line   31)
* mysqld, allow-suspicious-udfs option:  server-options.     (line   74)
* mysqld, ansi option:                   server-options.     (line   87)
* mysqld, as MySQL Cluster process <1>:  mysql-cluster-mysqld-process.
                                                             (line    6)
* mysqld, as MySQL Cluster process:      mysql-cluster-mysqld-command-options.
                                                             (line    6)
* mysqld, basedir option:                server-options.     (line   93)
* mysqld, big-tables option:             server-options.     (line  106)
* mysqld, bind-address option:           server-options.     (line  123)
* mysqld, binlog-do-db option:           binary-log.         (line  124)
* mysqld, binlog-format option:          server-options.     (line  132)
* mysqld, binlog-ignore-db option:       binary-log.         (line  145)
* mysqld, binlog-row-event-max-size option: server-options.  (line  177)
* mysqld, bootstrap option:              server-options.     (line  191)
* mysqld, character-set-client-handshake option: server-options.
                                                             (line  212)
* mysqld, character-set-filesystem option: server-options.   (line  223)
* mysqld, character-set-server option:   server-options.     (line  238)
* mysqld, character-sets-dir option:     server-options.     (line  199)
* mysqld, chroot option:                 server-options.     (line  253)
* mysqld, collation-server option:       server-options.     (line  263)
* mysqld, command options:               server-options.     (line    6)
* mysqld, console option:                server-options.     (line  276)
* mysqld, core-file option:              server-options.     (line  286)
* mysqld, datadir option:                server-options.     (line  298)
* mysqld, debug option:                  server-options.     (line  310)
* mysqld, default-character-set option:  server-options.     (line  336)
* mysqld, default-collation option:      server-options.     (line  346)
* mysqld, default-storage-engine option: server-options.     (line  359)
* mysqld, default-table-type option:     server-options.     (line  364)
* mysqld, default-time-zone option:      server-options.     (line  372)
* mysqld, delay-key-write option <1>:    myisam-start.       (line   35)
* mysqld, delay-key-write option:        server-options.     (line  382)
* mysqld, des-key-file option:           server-options.     (line  408)
* mysqld, disconnect-slave-event-count option: server-options.
                                                             (line  413)
* mysqld, enable-named-pipe option:      server-options.     (line  421)
* mysqld, enable-pstack option:          server-options.     (line  433)
* mysqld, event-scheduler option:        server-options.     (line  477)
* mysqld, exit-info option:              server-options.     (line  497)
* mysqld, external-locking option:       server-options.     (line  506)
* mysqld, flush option:                  server-options.     (line  525)
* mysqld, gdb option:                    server-options.     (line  539)
* mysqld, general-log option:            server-options.     (line  550)
* mysqld, help option:                   server-options.     (line   49)
* mysqld, init-file option:              server-options.     (line  569)
* mysqld, innodb option:                 innodb-parameters.  (line  162)
* mysqld, innodb_status_file option:     innodb-parameters.  (line  167)
* mysqld, language option:               server-options.     (line  589)
* mysqld, large-pages option:            server-options.     (line  605)
* mysqld, local-infile option:           privileges-options. (line   40)
* mysqld, log option:                    server-options.     (line  635)
* mysqld, log-bin option:                server-options.     (line  654)
* mysqld, log-bin-index option:          server-options.     (line  669)
* mysqld, log-bin-trust-function-creators option: server-options.
                                                             (line  678)
* mysqld, log-error option:              server-options.     (line  696)
* mysqld, log-isam option:               server-options.     (line  711)
* mysqld, log-long-format option:        server-options.     (line  719)
* mysqld, log-output option:             server-options.     (line  731)
* mysqld, log-queries-not-using-indexes option: server-options.
                                                             (line  764)
* mysqld, log-short-format option:       server-options.     (line  778)
* mysqld, log-slave-updates option:      replication-options.
                                                             (line  126)
* mysqld, log-slow-admin-statements option: server-options.  (line  788)
* mysqld, log-slow-queries option:       server-options.     (line  797)
* mysqld, log-slow-slave-statements option: server-options.  (line  818)
* mysqld, log-tc option:                 server-options.     (line  831)
* mysqld, log-tc-size option:            server-options.     (line  843)
* mysqld, log-warnings option <1>:       replication-options.
                                                             (line  146)
* mysqld, log-warnings option:           server-options.     (line  853)
* mysqld, low-priority-updates option:   server-options.     (line  873)
* mysqld, master-connect-retry option:   replication-options.
                                                             (line  156)
* mysqld, master-host option:            replication-options.
                                                             (line  170)
* mysqld, master-info-file option:       replication-options.
                                                             (line  179)
* mysqld, master-password option:        replication-options.
                                                             (line  185)
* mysqld, master-port option:            replication-options.
                                                             (line  195)
* mysqld, master-retry-count option:     replication-options.
                                                             (line  204)
* mysqld, master-ssl option:             replication-options.
                                                             (line  219)
* mysqld, master-ssl-ca option:          replication-options.
                                                             (line  219)
* mysqld, master-ssl-capath option:      replication-options.
                                                             (line  219)
* mysqld, master-ssl-cert option:        replication-options.
                                                             (line  219)
* mysqld, master-ssl-cipher option:      replication-options.
                                                             (line  219)
* mysqld, master-ssl-key option:         replication-options.
                                                             (line  219)
* mysqld, master-user option:            replication-options.
                                                             (line  234)
* mysqld, max-binlog-dump-events option: server-options.     (line  908)
* mysqld, max-relay-log-size option:     replication-options.
                                                             (line  245)
* mysqld, memlock option:                server-options.     (line  916)
* mysqld, min-examined-row-limit option: server-options.     (line  892)
* mysqld, myisam-recover option <1>:     myisam-start.       (line   31)
* mysqld, myisam-recover option:         server-options.     (line  953)
* mysqld, MySQL server:                  mysqld-server.      (line   19)
* mysqld, ndb-cluster-connection-pool option: mysql-cluster-mysqld-command-options.
                                                             (line   18)
* mysqld, ndb-connectstring option:      mysql-cluster-mysqld-command-options.
                                                             (line   46)
* mysqld, ndbcluster option:             mysql-cluster-mysqld-command-options.
                                                             (line   51)
* mysqld, old-passwords option <1>:      privileges-options. (line   45)
* mysqld, old-passwords option:          server-options.     (line  995)
* mysqld, old-style-user-limits option:  server-options.     (line 1010)
* mysqld, one-thread option:             server-options.     (line 1021)
* mysqld, open-files-limit option:       server-options.     (line 1031)
* mysqld, pid-file option:               server-options.     (line 1055)
* mysqld, port option:                   server-options.     (line 1069)
* mysqld, port-open-timeout option:      server-options.     (line 1084)
* mysqld, read-only option:              replication-options.
                                                             (line  251)
* mysqld, relay-log option:              replication-options.
                                                             (line  258)
* mysqld, relay-log-index option:        replication-options.
                                                             (line  269)
* mysqld, relay-log-info-file option:    replication-options.
                                                             (line  275)
* mysqld, relay-log-purge option:        replication-options.
                                                             (line  281)
* mysqld, relay-log-space-limit option:  replication-options.
                                                             (line  288)
* mysqld, replicate-do-db option:        replication-options.
                                                             (line  309)
* mysqld, replicate-do-table option:     replication-options.
                                                             (line  402)
* mysqld, replicate-ignore-db option:    replication-options.
                                                             (line  409)
* mysqld, replicate-ignore-table option: replication-options.
                                                             (line  456)
* mysqld, replicate-rewrite-db option:   replication-options.
                                                             (line  465)
* mysqld, replicate-same-server-id option: replication-options.
                                                             (line  484)
* mysqld, replicate-wild-do-table option: replication-options.
                                                             (line  498)
* mysqld, replicate-wild-ignore-table option: replication-options.
                                                             (line  530)
* mysqld, report-host option:            replication-options.
                                                             (line  547)
* mysqld, report-password option:        replication-options.
                                                             (line  566)
* mysqld, report-port option:            replication-options.
                                                             (line  558)
* mysqld, report-user option:            replication-options.
                                                             (line  573)
* mysqld, role in MySQL Cluster:         mysql-cluster-basics.
                                                             (line    6)
* mysqld, safe-mode option:              server-options.     (line 1097)
* mysqld, safe-show-database option <1>: privileges-options. (line   57)
* mysqld, safe-show-database option:     server-options.     (line 1103)
* mysqld, safe-user-create option <1>:   privileges-options. (line   67)
* mysqld, safe-user-create option:       server-options.     (line 1116)
* mysqld, secure-auth option <1>:        privileges-options. (line   82)
* mysqld, secure-auth option:            server-options.     (line 1137)
* mysqld, secure-file-priv option <1>:   privileges-options. (line   91)
* mysqld, secure-file-priv option:       server-options.     (line 1151)
* mysqld, shared-memory option:          server-options.     (line 1168)
* mysqld, shared-memory-base-name option: server-options.    (line 1173)
* mysqld, show-slave-auth-info option:   replication-options.
                                                             (line  580)
* mysqld, skip-concurrent-insert option: server-options.     (line 1179)
* mysqld, skip-external-locking option:  server-options.     (line 1185)
* mysqld, skip-grant-tables option <1>:  privileges-options. (line   99)
* mysqld, skip-grant-tables option:      server-options.     (line 1193)
* mysqld, skip-host-cache option:        server-options.     (line 1209)
* mysqld, skip-innodb option:            server-options.     (line 1215)
* mysqld, skip-merge option:             privileges-options. (line  110)
* mysqld, skip-name-resolve option <1>:  privileges-options. (line  119)
* mysqld, skip-name-resolve option:      server-options.     (line 1221)
* mysqld, skip-ndbcluster option:        mysql-cluster-mysqld-command-options.
                                                             (line   59)
* mysqld, skip-networking option <1>:    privileges-options. (line  124)
* mysqld, skip-networking option:        server-options.     (line 1228)
* mysqld, skip-safemalloc option:        server-options.     (line 1275)
* mysqld, skip-show-database option <1>: privileges-options. (line  129)
* mysqld, skip-show-database option:     server-options.     (line 1283)
* mysqld, skip-slave-start option:       replication-options.
                                                             (line  586)
* mysqld, skip-stack-trace option:       server-options.     (line 1299)
* mysqld, skip-symbolic-links option:    server-options.     (line 1258)
* mysqld, skip-thread-priority option:   server-options.     (line 1306)
* mysqld, slave-load-tmpdir option:      replication-options.
                                                             (line  598)
* mysqld, slave-net-timeout option:      replication-options.
                                                             (line  619)
* mysqld, slave-skip-errors option:      replication-options.
                                                             (line  630)
* mysqld, slave_compressed_protocol option: replication-options.
                                                             (line  592)
* mysqld, slow-query-log option:         server-options.     (line 1310)
* mysqld, socket option:                 server-options.     (line 1329)
* mysqld, sporadic-binlog-dump-fail option: server-options.  (line 1236)
* mysqld, sql-mode option:               server-options.     (line 1355)
* mysqld, SSL options <1>:               privileges-options. (line  139)
* mysqld, SSL options:                   server-options.     (line 1245)
* mysqld, standalone option:             server-options.     (line 1251)
* mysqld, starting:                      changing-mysql-user.
                                                             (line    6)
* mysqld, symbolic-links option:         server-options.     (line 1258)
* mysqld, sysdate-is-now option:         server-options.     (line 1390)
* mysqld, tc-heuristic-recover option:   server-options.     (line 1407)
* mysqld, temp-pool option:              server-options.     (line 1417)
* mysqld, tmpdir option:                 server-options.     (line 1445)
* mysqld, transaction-isolation option:  server-options.     (line 1431)
* mysqld, user option:                   server-options.     (line 1471)
* mysqld, version option:                server-options.     (line 1497)
* mysqld-safe-compatible option, mysqlmanager: instance-manager-command-options.
                                                             (line  153)
* mysqld-version option, mysqld_safe:    mysqld-safe.        (line  166)
* mysqld_multi:                          programs-overview.  (line   54)
* mysqld_multi, config-file option:      mysqld-multi.       (line   85)
* mysqld_multi, defaults-extra-file option: mysqld-multi.    (line   65)
* mysqld_multi, defaults-file option:    mysqld-multi.       (line   63)
* mysqld_multi, example option:          mysqld-multi.       (line   97)
* mysqld_multi, help option:             mysqld-multi.       (line   81)
* mysqld_multi, log option:              mysqld-multi.       (line  101)
* mysqld_multi, mysqladmin option:       mysqld-multi.       (line  106)
* mysqld_multi, mysqld option:           mysqld-multi.       (line  110)
* mysqld_multi, no-defaults option:      mysqld-multi.       (line   61)
* mysqld_multi, no-log option:           mysqld-multi.       (line  125)
* mysqld_multi, password option:         mysqld-multi.       (line  130)
* mysqld_multi, silent option:           mysqld-multi.       (line  136)
* mysqld_multi, tcp-ip option:           mysqld-multi.       (line  140)
* mysqld_multi, user option:             mysqld-multi.       (line  148)
* mysqld_multi, verbose option:          mysqld-multi.       (line  153)
* mysqld_multi, version option:          mysqld-multi.       (line  157)
* mysqld_safe:                           programs-overview.  (line   42)
* mysqld_safe, autoclose option:         mysqld-safe.        (line  110)
* mysqld_safe, basedir option:           mysqld-safe.        (line  122)
* mysqld_safe, core-file-size option:    mysqld-safe.        (line  126)
* mysqld_safe, datadir option:           mysqld-safe.        (line  131)
* mysqld_safe, defaults-extra-file option: mysqld-safe.      (line  135)
* mysqld_safe, defaults-file option:     mysqld-safe.        (line  142)
* mysqld_safe, help option:              mysqld-safe.        (line  106)
* mysqld_safe, ledir option:             mysqld-safe.        (line  148)
* mysqld_safe, log-error option:         mysqld-safe.        (line  153)
* mysqld_safe, mysqld option:            mysqld-safe.        (line  157)
* mysqld_safe, mysqld-version option:    mysqld-safe.        (line  166)
* mysqld_safe, nice option:              mysqld-safe.        (line  176)
* mysqld_safe, no-defaults option:       mysqld-safe.        (line  181)
* mysqld_safe, open-files-limit option:  mysqld-safe.        (line  186)
* mysqld_safe, pid-file option:          mysqld-safe.        (line  192)
* mysqld_safe, port option:              mysqld-safe.        (line  196)
* mysqld_safe, skip-kill-mysqld option:  mysqld-safe.        (line  202)
* mysqld_safe, skip-syslog option:       mysqld-safe.        (line  212)
* mysqld_safe, socket option:            mysqld-safe.        (line  207)
* mysqld_safe, syslog option:            mysqld-safe.        (line  212)
* mysqld_safe, syslog-tag option:        mysqld-safe.        (line  219)
* mysqld_safe, timezone option:          mysqld-safe.        (line  227)
* mysqld_safe, user option:              mysqld-safe.        (line  233)
* mysqldump <1>:                         programs-overview.  (line  137)
* mysqldump:                             upgrading-to-arch.  (line   47)
* mysqldump, add-drop-database option:   mysqldump.          (line  259)
* mysqldump, add-drop-table option:      mysqldump.          (line  264)
* mysqldump, add-locks option:           mysqldump.          (line  268)
* mysqldump, all-databases option:       mysqldump.          (line  274)
* mysqldump, all-tablespaces option:     mysqldump.          (line  280)
* mysqldump, allow-keywords option:      mysqldump.          (line  289)
* mysqldump, character-sets-dir option:  mysqldump.          (line  294)
* mysqldump, comments option:            mysqldump.          (line  299)
* mysqldump, compact option:             mysqldump.          (line  306)
* mysqldump, compatible option:          mysqldump.          (line  321)
* mysqldump, complete-insert option:     mysqldump.          (line  341)
* mysqldump, compress option:            mysqldump.          (line  345)
* mysqldump, create-options option:      mysqldump.          (line  350)
* mysqldump, databases option:           mysqldump.          (line  355)
* mysqldump, debug option:               mysqldump.          (line  363)
* mysqldump, debug-check option:         mysqldump.          (line  369)
* mysqldump, debug-info option:          mysqldump.          (line  374)
* mysqldump, default-character-set option: mysqldump.        (line  379)
* mysqldump, delayed-insert option:      mysqldump.          (line  388)
* mysqldump, delete-master-logs option:  mysqldump.          (line  392)
* mysqldump, disable-keys option:        mysqldump.          (line  398)
* mysqldump, dump-date option:           mysqldump.          (line  407)
* mysqldump, events option:              mysqldump.          (line  418)
* mysqldump, extended-insert option:     mysqldump.          (line  423)
* mysqldump, fields-enclosed-by option <1>: mysqlimport.     (line  152)
* mysqldump, fields-enclosed-by option:  mysqldump.          (line  431)
* mysqldump, fields-escaped-by option <1>: mysqlimport.      (line  156)
* mysqldump, fields-escaped-by option:   mysqldump.          (line  435)
* mysqldump, fields-optionally-enclosed-by option <1>: mysqlimport.
                                                             (line  154)
* mysqldump, fields-optionally-enclosed-by option: mysqldump.
                                                             (line  433)
* mysqldump, fields-terminated-by option <1>: mysqlimport.   (line  150)
* mysqldump, fields-terminated-by option: mysqldump.         (line  429)
* mysqldump, first-slave option:         mysqldump.          (line  441)
* mysqldump, flush-logs option:          mysqldump.          (line  445)
* mysqldump, flush-privileges option:    mysqldump.          (line  457)
* mysqldump, force option:               mysqldump.          (line  465)
* mysqldump, help option:                mysqldump.          (line  255)
* mysqldump, hex-blob option:            mysqldump.          (line  482)
* mysqldump, host option:                mysqldump.          (line  477)
* mysqldump, ignore-table option:        mysqldump.          (line  488)
* mysqldump, insert-ignore option:       mysqldump.          (line  494)
* mysqldump, lines-terminated-by option <1>: mysqlimport.    (line  180)
* mysqldump, lines-terminated-by option: mysqldump.          (line  498)
* mysqldump, lock-all-tables option:     mysqldump.          (line  504)
* mysqldump, lock-tables option:         mysqldump.          (line  511)
* mysqldump, log-error option:           mysqldump.          (line  525)
* mysqldump, master-data option:         mysqldump.          (line  530)
* mysqldump, no-autocommit option:       mysqldump.          (line  593)
* mysqldump, no-create-db option:        mysqldump.          (line  598)
* mysqldump, no-create-info option:      mysqldump.          (line  604)
* mysqldump, no-data option:             mysqldump.          (line  609)
* mysqldump, opt option:                 mysqldump.          (line  615)
* mysqldump, order-by-primary option:    mysqldump.          (line  628)
* mysqldump, password option:            mysqldump.          (line  635)
* mysqldump, pipe option:                mysqldump.          (line  646)
* mysqldump, port option:                mysqldump.          (line  652)
* mysqldump, problems <1>:               view-restrictions.  (line  107)
* mysqldump, problems:                   mysqldump.          (line  990)
* mysqldump, protocol option:            mysqldump.          (line  656)
* mysqldump, quick option:               mysqldump.          (line  663)
* mysqldump, quote-names option:         mysqldump.          (line  670)
* mysqldump, replace option:             mysqldump.          (line  679)
* mysqldump, result-file option:         mysqldump.          (line  684)
* mysqldump, routines option:            mysqldump.          (line  692)
* mysqldump, set-charset option:         mysqldump.          (line  717)
* mysqldump, single-transaction option:  mysqldump.          (line  723)
* mysqldump, skip-comments option:       mysqldump.          (line  758)
* mysqldump, skip-opt option:            mysqldump.          (line  762)
* mysqldump, socket option:              mysqldump.          (line  766)
* mysqldump, SSL options:                mysqldump.          (line  771)
* mysqldump, tab option:                 mysqldump.          (line  777)
* mysqldump, tables option:              mysqldump.          (line  803)
* mysqldump, triggers option:            mysqldump.          (line  808)
* mysqldump, tz-utc option:              mysqldump.          (line  813)
* mysqldump, user option:                mysqldump.          (line  825)
* mysqldump, verbose option:             mysqldump.          (line  829)
* mysqldump, version option:             mysqldump.          (line  833)
* mysqldump, views <1>:                  view-restrictions.  (line  107)
* mysqldump, views:                      mysqldump.          (line  990)
* mysqldump, where option:               mysqldump.          (line  837)
* mysqldump, workarounds <1>:            view-restrictions.  (line  107)
* mysqldump, workarounds:                mysqldump.          (line  990)
* mysqldump, xml option:                 mysqldump.          (line  849)
* mysqlhotcopy:                          programs-overview.  (line  196)
* mysqlhotcopy, addtodest option:        mysqlhotcopy.       (line   72)
* mysqlhotcopy, allowold option:         mysqlhotcopy.       (line   77)
* mysqlhotcopy, checkpoint option:       mysqlhotcopy.       (line   82)
* mysqlhotcopy, chroot option:           mysqlhotcopy.       (line   87)
* mysqlhotcopy, debug option:            mysqlhotcopy.       (line   93)
* mysqlhotcopy, dryrun option:           mysqlhotcopy.       (line   97)
* mysqlhotcopy, flushlog option:         mysqlhotcopy.       (line  101)
* mysqlhotcopy, help option:             mysqlhotcopy.       (line   68)
* mysqlhotcopy, host option:             mysqlhotcopy.       (line  105)
* mysqlhotcopy, keepold option:          mysqlhotcopy.       (line  111)
* mysqlhotcopy, method option:           mysqlhotcopy.       (line  115)
* mysqlhotcopy, noindices option:        mysqlhotcopy.       (line  119)
* mysqlhotcopy, password option:         mysqlhotcopy.       (line  125)
* mysqlhotcopy, port option:             mysqlhotcopy.       (line  135)
* mysqlhotcopy, quiet option:            mysqlhotcopy.       (line  139)
* mysqlhotcopy, record_log_pos option:   mysqlhotcopy.       (line  143)
* mysqlhotcopy, regexp option:           mysqlhotcopy.       (line  148)
* mysqlhotcopy, resetmaster option:      mysqlhotcopy.       (line  153)
* mysqlhotcopy, resetslave option:       mysqlhotcopy.       (line  157)
* mysqlhotcopy, socket option:           mysqlhotcopy.       (line  161)
* mysqlhotcopy, suffix option:           mysqlhotcopy.       (line  165)
* mysqlhotcopy, tmpdir option:           mysqlhotcopy.       (line  169)
* mysqlhotcopy, user option:             mysqlhotcopy.       (line  173)
* mysqlimport <1>:                       load-data.          (line   61)
* mysqlimport <2>:                       programs-overview.  (line  142)
* mysqlimport:                           upgrading-to-arch.  (line   47)
* mysqlimport, character-sets-dir option: mysqlimport.       (line  110)
* mysqlimport, columns option:           mysqlimport.        (line  115)
* mysqlimport, compress option:          mysqlimport.        (line  121)
* mysqlimport, debug option:             mysqlimport.        (line  126)
* mysqlimport, debug-check option:       mysqlimport.        (line  131)
* mysqlimport, debug-info option:        mysqlimport.        (line  136)
* mysqlimport, default-character-set option: mysqlimport.    (line  141)
* mysqlimport, delete option:            mysqlimport.        (line  146)
* mysqlimport, force option:             mysqlimport.        (line  161)
* mysqlimport, help option:              mysqlimport.        (line  106)
* mysqlimport, host option:              mysqlimport.        (line  167)
* mysqlimport, ignore option:            mysqlimport.        (line  172)
* mysqlimport, ignore-lines option:      mysqlimport.        (line  176)
* mysqlimport, local option:             mysqlimport.        (line  189)
* mysqlimport, lock-tables option:       mysqlimport.        (line  200)
* mysqlimport, low-priority option:      mysqlimport.        (line  205)
* mysqlimport, password option:          mysqlimport.        (line  211)
* mysqlimport, pipe option:              mysqlimport.        (line  222)
* mysqlimport, port option:              mysqlimport.        (line  228)
* mysqlimport, protocol option:          mysqlimport.        (line  232)
* mysqlimport, replace option:           mysqlimport.        (line  239)
* mysqlimport, silent option:            mysqlimport.        (line  249)
* mysqlimport, socket option:            mysqlimport.        (line  253)
* mysqlimport, SSL options:              mysqlimport.        (line  258)
* mysqlimport, use-threads option:       mysqlimport.        (line  268)
* mysqlimport, user option:              mysqlimport.        (line  264)
* mysqlimport, verbose option:           mysqlimport.        (line  273)
* mysqlimport, version option:           mysqlimport.        (line  277)
* mysqlmanager:                          programs-overview.  (line  201)
* mysqlmanager, add-user option:         instance-manager-command-options.
                                                             (line   27)
* mysqlmanager, angel-pid-file option:   instance-manager-command-options.
                                                             (line   32)
* mysqlmanager, bind-address option:     instance-manager-command-options.
                                                             (line   46)
* mysqlmanager, check-password-file option: instance-manager-command-options.
                                                             (line   50)
* mysqlmanager, clean-password-file option: instance-manager-command-options.
                                                             (line   55)
* mysqlmanager, debug option:            instance-manager-command-options.
                                                             (line   60)
* mysqlmanager, default-mysqld-path option: instance-manager-command-options.
                                                             (line   65)
* mysqlmanager, defaults-file option:    instance-manager-command-options.
                                                             (line   74)
* mysqlmanager, drop-user option:        instance-manager-command-options.
                                                             (line   86)
* mysqlmanager, edit-user option:        instance-manager-command-options.
                                                             (line   91)
* mysqlmanager, help option:             instance-manager-command-options.
                                                             (line   23)
* mysqlmanager, install option:          instance-manager-command-options.
                                                             (line   97)
* mysqlmanager, list-users option:       instance-manager-command-options.
                                                             (line  102)
* mysqlmanager, log option:              instance-manager-command-options.
                                                             (line  107)
* mysqlmanager, monitoring-interval option: instance-manager-command-options.
                                                             (line  125)
* mysqlmanager, mysqld-safe-compatible option: instance-manager-command-options.
                                                             (line  153)
* mysqlmanager, password option:         instance-manager-command-options.
                                                             (line  159)
* mysqlmanager, password-file option:    instance-manager-command-options.
                                                             (line  166)
* mysqlmanager, pid-file option:         instance-manager-command-options.
                                                             (line  173)
* mysqlmanager, port option:             instance-manager-command-options.
                                                             (line  180)
* mysqlmanager, print-defaults option:   instance-manager-command-options.
                                                             (line  185)
* mysqlmanager, print-password-line option: instance-manager-command-options.
                                                             (line  190)
* mysqlmanager, remove option:           instance-manager-command-options.
                                                             (line  198)
* mysqlmanager, run-as-service option:   instance-manager-command-options.
                                                             (line  204)
* mysqlmanager, socket option:           instance-manager-command-options.
                                                             (line  210)
* mysqlmanager, standalone option:       instance-manager-command-options.
                                                             (line  216)
* mysqlmanager, user option:             instance-manager-command-options.
                                                             (line  222)
* mysqlmanager, username option:         instance-manager-command-options.
                                                             (line  233)
* mysqlmanager, version option:          instance-manager-command-options.
                                                             (line  238)
* mysqlmanager, wait-timeout option:     instance-manager-command-options.
                                                             (line  242)
* mysqlshow:                             programs-overview.  (line  147)
* mysqlshow, character-sets-dir option:  mysqlshow.          (line  101)
* mysqlshow, compress option:            mysqlshow.          (line  106)
* mysqlshow, count option:               mysqlshow.          (line  111)
* mysqlshow, debug option:               mysqlshow.          (line  116)
* mysqlshow, debug-check option:         mysqlshow.          (line  121)
* mysqlshow, debug-info option:          mysqlshow.          (line  126)
* mysqlshow, default-character-set option: mysqlshow.        (line  131)
* mysqlshow, help option:                mysqlshow.          (line   97)
* mysqlshow, host option:                mysqlshow.          (line  136)
* mysqlshow, keys option:                mysqlshow.          (line  140)
* mysqlshow, password option:            mysqlshow.          (line  144)
* mysqlshow, pipe option:                mysqlshow.          (line  158)
* mysqlshow, port option:                mysqlshow.          (line  164)
* mysqlshow, protocol option:            mysqlshow.          (line  168)
* mysqlshow, show-table-type option:     mysqlshow.          (line  175)
* mysqlshow, socket option:              mysqlshow.          (line  180)
* mysqlshow, SSL options:                mysqlshow.          (line  185)
* mysqlshow, status option:              mysqlshow.          (line  191)
* mysqlshow, user option:                mysqlshow.          (line  195)
* mysqlshow, verbose option:             mysqlshow.          (line  199)
* mysqlshow, version option:             mysqlshow.          (line  205)
* mysqlslap:                             programs-overview.  (line  152)
* mysqlslap, auto-generate-sql option:   mysqlslap.          (line  142)
* mysqlslap, auto-generate-sql-add-autoincrement option: mysqlslap.
                                                             (line  147)
* mysqlslap, auto-generate-sql-execute-number option: mysqlslap.
                                                             (line  152)
* mysqlslap, auto-generate-sql-guid-primary option: mysqlslap.
                                                             (line  157)
* mysqlslap, auto-generate-sql-load-type option: mysqlslap.  (line  162)
* mysqlslap, auto-generate-sql-secondary-indexes option: mysqlslap.
                                                             (line  170)
* mysqlslap, auto-generate-sql-unique-query-number option: mysqlslap.
                                                             (line  176)
* mysqlslap, auto-generate-sql-unique-write-number option: mysqlslap.
                                                             (line  184)
* mysqlslap, auto-generate-sql-write-number option: mysqlslap.
                                                             (line  190)
* mysqlslap, commit option:              mysqlslap.          (line  195)
* mysqlslap, compress option:            mysqlslap.          (line  200)
* mysqlslap, concurrency option:         mysqlslap.          (line  205)
* mysqlslap, create option:              mysqlslap.          (line  210)
* mysqlslap, create-schema option:       mysqlslap.          (line  215)
* mysqlslap, csv option:                 mysqlslap.          (line  220)
* mysqlslap, debug option:               mysqlslap.          (line  226)
* mysqlslap, debug-check option:         mysqlslap.          (line  231)
* mysqlslap, debug-info option:          mysqlslap.          (line  236)
* mysqlslap, delimiter option:           mysqlslap.          (line  241)
* mysqlslap, detach option:              mysqlslap.          (line  246)
* mysqlslap, engine option:              mysqlslap.          (line  252)
* mysqlslap, help option:                mysqlslap.          (line  138)
* mysqlslap, host option:                mysqlslap.          (line  256)
* mysqlslap, iterations option:          mysqlslap.          (line  260)
* mysqlslap, lock-directory option:      mysqlslap.          (line  264)
* mysqlslap, number-char-cols option:    mysqlslap.          (line  269)
* mysqlslap, number-int-cols option:     mysqlslap.          (line  274)
* mysqlslap, number-of-queries option:   mysqlslap.          (line  279)
* mysqlslap, only-print option:          mysqlslap.          (line  284)
* mysqlslap, password option:            mysqlslap.          (line  289)
* mysqlslap, pipe option:                mysqlslap.          (line  302)
* mysqlslap, port option:                mysqlslap.          (line  308)
* mysqlslap, post-query option:          mysqlslap.          (line  312)
* mysqlslap, post-system option:         mysqlslap.          (line  318)
* mysqlslap, pre-query option:           mysqlslap.          (line  324)
* mysqlslap, pre-system option:          mysqlslap.          (line  330)
* mysqlslap, preserve-schema option:     mysqlslap.          (line  336)
* mysqlslap, protocol option:            mysqlslap.          (line  342)
* mysqlslap, query option:               mysqlslap.          (line  349)
* mysqlslap, silent option:              mysqlslap.          (line  354)
* mysqlslap, slave option:               mysqlslap.          (line  358)
* mysqlslap, socket option:              mysqlslap.          (line  365)
* mysqlslap, SSL options:                mysqlslap.          (line  370)
* mysqlslap, use-threads option:         mysqlslap.          (line  376)
* mysqlslap, user option:                mysqlslap.          (line  383)
* mysqlslap, verbose option:             mysqlslap.          (line  387)
* mysqlslap, version option:             mysqlslap.          (line  393)
* mysqltest, MySQL Test Suite:           mysql-test-suite.   (line    6)
* NAME_CONST():                          miscellaneous-functions.
                                                             (line  154)
* name_file option, comp_err:            comp-err.           (line   51)
* named pipes <1>:                       windows-testing.    (line    6)
* named pipes:                           windows-select-server.
                                                             (line   33)
* named-commands option, mysql:          mysql-command-options.
                                                             (line  265)
* names:                                 identifiers.        (line   13)
* names, case sensitivity:               identifier-case-sensitivity.
                                                             (line    6)
* names, variables:                      user-variables.     (line    6)
* naming, releases of MySQL:             choosing-version.   (line   55)
* NATIONAL CHAR data type:               string-type-overview.
                                                             (line   80)
* NATIONAL VARCHAR data type:            string-type-overview.
                                                             (line  110)
* native backup and restore, and management client: mysql-cluster-backup-using-management-client.
                                                             (line   15)
* native backup and restore, backup identifiers: mysql-cluster-backup-using-management-client.
                                                             (line   58)
* native functions, adding:              adding-native-function.
                                                             (line    6)
* native thread support:                 which-os.           (line    6)
* NATURAL LEFT JOIN:                     join.               (line    6)
* NATURAL LEFT OUTER JOIN:               join.               (line    6)
* NATURAL RIGHT JOIN:                    join.               (line    6)
* NATURAL RIGHT OUTER JOIN:              join.               (line    6)
* NCHAR data type:                       string-type-overview.
                                                             (line   80)
* NDB:                                   faqs-mysql-cluster. (line   15)
* ndb option, perror:                    perror.             (line   43)
* NDB storage engine:                    mysql-cluster.      (line   26)
* NDB storage engine, FAQ:               faqs-mysql-cluster. (line    6)
* NDB tables, and MySQL root user:       mysql-cluster-security-mysql-privileges.
                                                             (line   46)
* NDB utilities, security issues:        mysql-cluster-security-mysql-security-procedures.
                                                             (line   74)
* ndb-cluster-connection-pool option, mysqld: mysql-cluster-mysqld-command-options.
                                                             (line   18)
* ndb-connectstring option, mysqld:      mysql-cluster-mysqld-command-options.
                                                             (line   46)
* ndb-connectstring option, ndb_config:  mysql-cluster-utilities-ndb-config.
                                                             (line   30)
* ndb_apply_status table (MySQL Cluster replication) <1>: mysql-cluster-replication-failover.
                                                             (line   10)
* ndb_apply_status table (MySQL Cluster replication): mysql-cluster-replication-schema.
                                                             (line   79)
* ndb_binlog_index table (MySQL Cluster replication) <1>: mysql-cluster-replication-failover.
                                                             (line   18)
* ndb_binlog_index table (MySQL Cluster replication): mysql-cluster-replication-schema.
                                                             (line    6)
* ndb_config:                            mysql-cluster-utilities.
                                                             (line   25)
* ndb_config, config-file option:        mysql-cluster-utilities-ndb-config.
                                                             (line   40)
* ndb_config, fields option:             mysql-cluster-utilities-ndb-config.
                                                             (line   92)
* ndb_config, host option:               mysql-cluster-utilities-ndb-config.
                                                             (line   66)
* ndb_config, id option:                 mysql-cluster-utilities-ndb-config.
                                                             (line   71)
* ndb_config, ndb-connectstring option:  mysql-cluster-utilities-ndb-config.
                                                             (line   30)
* ndb_config, nodeid option:             mysql-cluster-utilities-ndb-config.
                                                             (line   73)
* ndb_config, nodes option:              mysql-cluster-utilities-ndb-config.
                                                             (line   78)
* ndb_config, query option:              mysql-cluster-utilities-ndb-config.
                                                             (line   47)
* ndb_config, rows option:               mysql-cluster-utilities-ndb-config.
                                                             (line  102)
* ndb_config, type option:               mysql-cluster-utilities-ndb-config.
                                                             (line   86)
* ndb_config, usage option:              mysql-cluster-utilities-ndb-config.
                                                             (line   20)
* ndb_config, version option:            mysql-cluster-utilities-ndb-config.
                                                             (line   25)
* ndb_cpcd:                              mysql-cluster-utilities.
                                                             (line   25)
* ndb_delete_all:                        mysql-cluster-utilities.
                                                             (line   25)
* ndb_delete_all, transactional option:  mysql-cluster-utilities-ndb-delete-all.
                                                             (line   19)
* ndb_desc:                              mysql-cluster-utilities.
                                                             (line   25)
* ndb_desc, extra-partition-info option: mysql-cluster-utilities-ndb-desc.
                                                             (line   66)
* ndb_drop_index:                        mysql-cluster-utilities.
                                                             (line   25)
* ndb_drop_table:                        mysql-cluster-utilities.
                                                             (line   25)
* ndb_error_reporter:                    mysql-cluster-utilities.
                                                             (line   25)
* ndb_mgm (MySQL Cluster management node client): mysql-cluster-multi-initial.
                                                             (line   34)
* ndb_mgmd (MySQL Cluster), defined:     mysql-cluster-basics.
                                                             (line    6)
* ndb_print_backup_file:                 mysql-cluster-utilities.
                                                             (line   25)
* ndb_print_schema_file:                 mysql-cluster-utilities.
                                                             (line   25)
* ndb_print_sys_file:                    mysql-cluster-utilities.
                                                             (line   25)
* ndb_restore, attribute promotion:      mysql-cluster-restore.
                                                             (line   72)
* ndb_restore, errors:                   mysql-cluster-restore.
                                                             (line  327)
* ndb_schema table (MySQL Cluster replication): mysql-cluster-replication-schema.
                                                             (line  136)
* ndb_select_all:                        mysql-cluster-utilities.
                                                             (line   25)
* ndb_select_all, delimiter option:      mysql-cluster-utilities-ndb-select-all.
                                                             (line   48)
* ndb_select_all, descending option:     mysql-cluster-utilities-ndb-select-all.
                                                             (line   33)
* ndb_select_all, disk option:           mysql-cluster-utilities-ndb-select-all.
                                                             (line   55)
* ndb_select_all, gci option:            mysql-cluster-utilities-ndb-select-all.
                                                             (line   65)
* ndb_select_all, header option:         mysql-cluster-utilities-ndb-select-all.
                                                             (line   38)
* ndb_select_all, lock option:           mysql-cluster-utilities-ndb-select-all.
                                                             (line   14)
* ndb_select_all, nodata option:         mysql-cluster-utilities-ndb-select-all.
                                                             (line   76)
* ndb_select_all, order option:          mysql-cluster-utilities-ndb-select-all.
                                                             (line   27)
* ndb_select_all, rowid option:          mysql-cluster-utilities-ndb-select-all.
                                                             (line   60)
* ndb_select_all, tupscan option:        mysql-cluster-utilities-ndb-select-all.
                                                             (line   72)
* ndb_select_all, useHexFormat option:   mysql-cluster-utilities-ndb-select-all.
                                                             (line   42)
* ndb_select_count:                      mysql-cluster-utilities.
                                                             (line   25)
* ndb_show_tables:                       mysql-cluster-utilities.
                                                             (line   25)
* ndb_show_tables, loops option:         mysql-cluster-utilities-ndb-show-tables.
                                                             (line   17)
* ndb_show_tables, parsable option:      mysql-cluster-utilities-ndb-show-tables.
                                                             (line   23)
* ndb_show_tables, type option:          mysql-cluster-utilities-ndb-show-tables.
                                                             (line   28)
* ndb_show_tables, unqualified option:   mysql-cluster-utilities-ndb-show-tables.
                                                             (line   42)
* ndb_size.pl:                           mysql-cluster-utilities.
                                                             (line   25)
* ndb_size.pl (utility):                 faqs-mysql-cluster. (line  367)
* ndb_waiter:                            mysql-cluster-utilities.
                                                             (line   25)
* ndb_waiter, no-contact option:         mysql-cluster-utilities-ndb-waiter.
                                                             (line   42)
* ndb_waiter, not-started option:        mysql-cluster-utilities-ndb-waiter.
                                                             (line   48)
* ndb_waiter, timeout option:            mysql-cluster-utilities-ndb-waiter.
                                                             (line   54)
* ndbcluster option, mysqld:             mysql-cluster-mysqld-command-options.
                                                             (line   51)
* ndbd (MySQL Cluster), defined:         mysql-cluster-basics.
                                                             (line    6)
* negative values:                       number-syntax.      (line    6)
* nested queries:                        subqueries.         (line   20)
* net etiquette:                         mailing-list-use.   (line    6)
* net_buffer_length variable:            mysql-command-options.
                                                             (line  556)
* netmask notation, in mysql.user table: connection-access.  (line   42)
* NetWare:                               netware-installation.
                                                             (line    6)
* network ports, and MySQL Cluster:      mysql-cluster-security-networking-issues.
                                                             (line  182)
* New features in MySQL Cluster:         mysql-cluster-roadmap.
                                                             (line   13)
* new procedures, adding:                adding-procedures.  (line   11)
* new users, adding <1>:                 quick-install.      (line  166)
* new users, adding:                     installing-binary.  (line  167)
* newline (\n) <1>:                      load-data.          (line  414)
* newline (\n):                          string-syntax.      (line   52)
* next-key lock <1>:                     innodb-next-key-locking.
                                                             (line    6)
* next-key lock <2>:                     innodb-transaction-isolation.
                                                             (line   49)
* next-key lock:                         innodb-parameters.  (line  429)
* NFS, InnoDB <1>:                       innodb-restrictions.
                                                             (line   16)
* NFS, InnoDB:                           innodb-configuration.
                                                             (line   49)
* nice option, mysqld_safe:              mysqld-safe.        (line  176)
* no matching rows:                      no-matching-rows.   (line    6)
* no-auto-rehash option, mysql:          mysql-command-options.
                                                             (line  272)
* no-autocommit option, mysqldump:       mysqldump.          (line  593)
* no-beep option, mysql:                 mysql-command-options.
                                                             (line  278)
* no-beep option, mysqladmin:            mysqladmin.         (line  333)
* no-contact option, ndb_waiter:         mysql-cluster-utilities-ndb-waiter.
                                                             (line   42)
* no-create-db option, mysqldump:        mysqldump.          (line  598)
* no-create-info option, mysqldump:      mysqldump.          (line  604)
* no-data option, mysqldump:             mysqldump.          (line  609)
* no-debug option, make_win_bin_dist:    make-win-bin-dist.  (line   51)
* no-defaults option:                    option-file-options.
                                                             (line   15)
* no-defaults option, my_print_defaults: my-print-defaults.  (line   51)
* no-defaults option, mysqld_multi:      mysqld-multi.       (line   61)
* no-defaults option, mysqld_safe:       mysqld-safe.        (line  181)
* no-embedded option, make_win_bin_dist: make-win-bin-dist.  (line   55)
* no-log option, mysqld_multi:           mysqld-multi.       (line  125)
* no-named-commands option, mysql:       mysql-command-options.
                                                             (line  282)
* no-pager option, mysql:                mysql-command-options.
                                                             (line  286)
* no-symlinks option, myisamchk:         myisamchk-repair-options.
                                                             (line   46)
* no-tee option, mysql:                  mysql-command-options.
                                                             (line  290)
* NO_AUTO_CREATE_USER SQL mode:          server-sql-mode.    (line  160)
* NO_AUTO_VALUE_ON_ZERO SQL mode:        server-sql-mode.    (line  166)
* NO_BACKSLASH_ESCAPES SQL mode:         server-sql-mode.    (line  185)
* NO_DIR_IN_CREATE SQL mode:             server-sql-mode.    (line  191)
* NO_FIELD_OPTIONS SQL mode:             server-sql-mode.    (line  226)
* NO_KEY_OPTIONS SQL mode:               server-sql-mode.    (line  232)
* NO_TABLE_OPTIONS SQL mode:             server-sql-mode.    (line  238)
* NO_UNSIGNED_SUBTRACTION SQL mode:      server-sql-mode.    (line  244)
* NO_ZERO_DATE SQL mode:                 server-sql-mode.    (line  291)
* NO_ZERO_IN_DATE SQL mode:              server-sql-mode.    (line  297)
* nodata option, ndb_select_all:         mysql-cluster-utilities-ndb-select-all.
                                                             (line   76)
* node groups (MySQL Cluster):           mysql-cluster-nodes-groups.
                                                             (line    6)
* node identifiers (MySQL Cluster) <1>:  mysql-cluster-sci-definition.
                                                             (line   24)
* node identifiers (MySQL Cluster):      mysql-cluster-shm-definition.
                                                             (line   22)
* node logs (MySQL Cluster):             mysql-cluster-event-reports.
                                                             (line   12)
* nodeid option, ndb_config:             mysql-cluster-utilities-ndb-config.
                                                             (line   73)
* NODERESTART Events (MySQL Cluster):    mysql-cluster-log-events.
                                                             (line   89)
* nodes option, ndb_config:              mysql-cluster-utilities-ndb-config.
                                                             (line   78)
* noindices option, mysqlhotcopy:        mysqlhotcopy.       (line  119)
* non-delimited strings:                 datetime.           (line  122)
* Non-transactional tables:              non-transactional-tables.
                                                             (line    6)
* NoOfDiskPagesToDiskAfterRestartACC (DEPRECATED): mysql-cluster-ndbd-definition.
                                                             (line 1213)
* NoOfDiskPagesToDiskAfterRestartACC, calculating: mysql-cluster-config-lcp-params.
                                                             (line    6)
* NoOfDiskPagesToDiskAfterRestartTUP (DEPRECATED): mysql-cluster-ndbd-definition.
                                                             (line 1181)
* NoOfDiskPagesToDiskAfterRestartTUP, calculating: mysql-cluster-config-lcp-params.
                                                             (line    6)
* NoOfDiskPagesToDiskDuringRestartACC (DEPRECATED): mysql-cluster-ndbd-definition.
                                                             (line 1249)
* NoOfDiskPagesToDiskDuringRestartTUP (DEPRECATED): mysql-cluster-ndbd-definition.
                                                             (line 1228)
* NoOfFragmentLogFiles:                  mysql-cluster-ndbd-definition.
                                                             (line  605)
* NoOfFragmentLogFiles, calculating:     mysql-cluster-config-lcp-params.
                                                             (line    6)
* NoOfReplicas:                          mysql-cluster-ndbd-definition.
                                                             (line   71)
* nopager command, mysql:                mysql-commands.     (line  122)
* NOT BETWEEN:                           comparison-operators.
                                                             (line  197)
* not equal (!=):                        comparison-operators.
                                                             (line   82)
* not equal (<>):                        comparison-operators.
                                                             (line   82)
* NOT EXISTS, with subqueries:           exists-and-not-exists-subqueries.
                                                             (line    6)
* NOT IN:                                comparison-operators.
                                                             (line  265)
* NOT LIKE:                              string-comparison-functions.
                                                             (line  118)
* NOT NULL, constraint:                  constraint-invalid-data.
                                                             (line    6)
* NOT REGEXP:                            string-comparison-functions.
                                                             (line  144)
* NOT, logical:                          logical-operators.  (line   27)
* not-started option, ndb_waiter:        mysql-cluster-utilities-ndb-waiter.
                                                             (line   48)
* notee command, mysql:                  mysql-commands.     (line  128)
* Novell NetWare:                        netware-installation.
                                                             (line    6)
* NOW():                                 date-and-time-functions.
                                                             (line  700)
* NOWAIT (START BACKUP command):         mysql-cluster-backup-using-management-client.
                                                             (line   35)
* nowarning command, mysql:              mysql-commands.     (line  133)
* NUL <1>:                               load-data.          (line  412)
* NUL:                                   string-syntax.      (line   48)
* NULL <1>:                              problems-with-null. (line    6)
* NULL:                                  working-with-null.  (line    6)
* NULL value <1>:                        null-values.        (line    6)
* NULL value:                            working-with-null.  (line    6)
* NULL values, and AUTO_INCREMENT columns: problems-with-null.
                                                             (line   71)
* NULL values, and indexes:              create-table.       (line  410)
* NULL values, and TIMESTAMP columns:    problems-with-null. (line   71)
* NULL values, vs. empty values:         problems-with-null. (line    6)
* NULL, ORDER BY <1>:                    select.             (line  170)
* NULL, ORDER BY:                        order-by-optimization.
                                                             (line   87)
* NULL, testing for null <1>:            control-flow-functions.
                                                             (line   98)
* NULL, testing for null:                comparison-operators.
                                                             (line   70)
* NULLIF():                              control-flow-functions.
                                                             (line  129)
* number-char-cols option, mysqlslap:    mysqlslap.          (line  269)
* number-int-cols option, mysqlslap:     mysqlslap.          (line  274)
* number-of-queries option, mysqlslap:   mysqlslap.          (line  279)
* numbers:                               number-syntax.      (line    6)
* NUMERIC data type:                     numeric-type-overview.
                                                             (line  241)
* numeric types:                         storage-requirements.
                                                             (line   38)
* numeric-dump-file option, resolve_stack_dump: resolve-stack-dump.
                                                             (line   24)
* NumGeometries():                       geometrycollection-property-functions.
                                                             (line   21)
* NumInteriorRings():                    polygon-property-functions.
                                                             (line   49)
* NumPoints():                           linestring-property-functions.
                                                             (line   39)
* NVARCHAR data type:                    string-type-overview.
                                                             (line  110)
* obtaining information about partitions: partitioning-info. (line    6)
* Obtaining MySQL Cluster:               mysql-cluster-multi-install.
                                                             (line    6)
* OCT():                                 mathematical-functions.
                                                             (line  323)
* OCTET_LENGTH():                        string-functions.   (line  468)
* ODBC:                                  myodbc-connector.   (line   17)
* ODBC compatibility <1>:                join.               (line  145)
* ODBC compatibility <2>:                create-table.       (line  275)
* ODBC compatibility <3>:                comparison-operators.
                                                             (line  144)
* ODBC compatibility <4>:                type-conversion.    (line   40)
* ODBC compatibility <5>:                numeric-type-overview.
                                                             (line  223)
* ODBC compatibility:                    identifier-qualifiers.
                                                             (line   41)
* ODirect:                               mysql-cluster-ndbd-definition.
                                                             (line  846)
* offset option, mysqlbinlog:            mysqlbinlog.        (line  189)
* OLAP:                                  group-by-modifiers. (line    6)
* old-passwords option, mysqld <1>:      privileges-options. (line   45)
* old-passwords option, mysqld:          server-options.     (line  995)
* old-style-user-limits option, mysqld:  server-options.     (line 1010)
* OLD_PASSWORD():                        encryption-functions.
                                                             (line  239)
* old_server option, mysqlaccess:        mysqlaccess.        (line   94)
* ON DUPLICATE KEY:                      insert.             (line   12)
* one-database option, mysql:            mysql-command-options.
                                                             (line  295)
* one-thread option, mysqld:             server-options.     (line 1021)
* online location of manual:             manual-info.        (line    6)
* only-debug option, make_win_bin_dist:  make-win-bin-dist.  (line   59)
* only-print option, mysqlslap:          mysqlslap.          (line  284)
* ONLY_FULL_GROUP_BY SQL mode:           server-sql-mode.    (line  306)
* ONLY_FULL_GROUP_BY, SQL mode:          group-by-hidden-fields.
                                                             (line    6)
* OPEN:                                  open.               (line    6)
* Open Source, defined:                  what-is-mysql.      (line   42)
* open tables <1>:                       table-cache.        (line    6)
* open tables:                           mysqladmin.         (line  205)
* open-files-limit option, mysqld:       server-options.     (line 1031)
* open-files-limit option, mysqld_safe:  mysqld-safe.        (line  186)
* open_files_limit variable:             mysqlbinlog.        (line  317)
* OpenGIS:                               gis-introduction.   (line    6)
* Opening master dump table, thread state: slave-connection-thread-states.
                                                             (line   23)
* Opening mysql.ndb_apply_status, thread state: mysql-cluster-thread-states.
                                                             (line    8)
* Opening table, thread state:           general-thread-states.
                                                             (line  157)
* Opening tables, thread state:          general-thread-states.
                                                             (line  157)
* opening, tables:                       table-cache.        (line    6)
* opens:                                 mysqladmin.         (line  196)
* OpenSSL <1>:                           secure-using-ssl.   (line    6)
* OpenSSL:                               secure-connections. (line   14)
* operating systems, file-size limits:   full-table.         (line    6)
* operating systems, supported:          which-os.           (line    6)
* operating systems, Windows versus Unix: windows-vs-unix.   (line    6)
* operations, arithmetic:                arithmetic-functions.
                                                             (line   43)
* operators:                             functions.          (line   21)
* operators, assignment:                 user-variables.     (line    6)
* operators, cast <1>:                   cast-functions.     (line    6)
* operators, cast:                       arithmetic-functions.
                                                             (line    6)
* operators, logical:                    logical-operators.  (line    6)
* operators, precedence:                 operator-precedence.
                                                             (line    6)
* opt option, mysqldump:                 mysqldump.          (line  615)
* optimization, subquery:                in-subquery-optimization.
                                                             (line    6)
* optimization, tips:                    miscellaneous-optimization-tips.
                                                             (line    6)
* optimizations <1>:                     index-merge-optimization.
                                                             (line   12)
* optimizations:                         where-optimizations.
                                                             (line    6)
* optimize option, mysqlcheck:           mysqlcheck.         (line  277)
* OPTIMIZE TABLE:                        optimize-table.     (line    6)
* optimizer, controlling:                controlling-optimizer.
                                                             (line    6)
* optimizing, DISTINCT:                  distinct-optimization.
                                                             (line    6)
* optimizing, filesort:                  order-by-optimization.
                                                             (line  102)
* optimizing, GROUP BY:                  group-by-optimization.
                                                             (line   11)
* optimizing, LEFT JOIN:                 left-join-optimization.
                                                             (line    6)
* optimizing, LIMIT:                     limit-optimization. (line    6)
* optimizing, tables:                    table-optimization. (line    6)
* option files <1>:                      access-denied.      (line  101)
* option files:                          option-files.       (line   11)
* option modifiers:                      option-modifiers.   (line    6)
* options, command-line, mysql:          mysql-command-options.
                                                             (line    6)
* options, command-line, mysqladmin:     mysqladmin.         (line  226)
* options, configure:                    configure-options.  (line    6)
* options, embedded server:              libmysqld-options.  (line    6)
* options, libmysqld:                    libmysqld-options.  (line    6)
* options, myisamchk:                    myisamchk-general-options.
                                                             (line    6)
* options, provided by MySQL:            tutorial.           (line   17)
* options, replication:                  replication-features.
                                                             (line   33)
* OR <1>:                                index-merge-optimization.
                                                             (line   12)
* OR:                                    searching-on-two-keys.
                                                             (line    6)
* OR Index Merge optimization:           index-merge-optimization.
                                                             (line   12)
* OR, bitwise:                           bit-functions.      (line   18)
* OR, logical:                           logical-operators.  (line   63)
* Oracle compatibility <1>:              describe.           (line   37)
* Oracle compatibility <2>:              group-by-functions. (line  226)
* Oracle compatibility:                  extensions-to-ansi. (line   94)
* ORACLE SQL mode:                       server-sql-mode.    (line  480)
* ORD():                                 string-functions.   (line  472)
* ORDER BY <1>:                          select.             (line  142)
* ORDER BY <2>:                          alter-table.        (line  437)
* ORDER BY:                              sorting-rows.       (line    6)
* ORDER BY, NULL <1>:                    select.             (line  170)
* ORDER BY, NULL:                        order-by-optimization.
                                                             (line   87)
* order option, ndb_select_all:          mysql-cluster-utilities-ndb-select-all.
                                                             (line   27)
* order-by-primary option, mysqldump:    mysqldump.          (line  628)
* out_dir option, comp_err:              comp-err.           (line   55)
* out_file option, comp_err:             comp-err.           (line   60)
* OUTFILE:                               select.             (line  301)
* Overlaps():                            functions-that-test-spatial-relationships-between-geometries.
                                                             (line   62)
* overview:                              introduction.       (line   17)
* packages, list of:                     packages.           (line    6)
* PAD_CHAR_TO_FULL_LENGTH SQL mode:      server-sql-mode.    (line  319)
* pager command, mysql:                  mysql-commands.     (line  137)
* pager option, mysql:                   mysql-command-options.
                                                             (line  301)
* parallel-recover option, myisamchk:    myisamchk-repair-options.
                                                             (line   58)
* parameters, server:                    server-parameters.  (line    6)
* parentheses ( and ):                   operator-precedence.
                                                             (line   37)
* parsable option, ndb_show_tables:      mysql-cluster-utilities-ndb-show-tables.
                                                             (line   23)
* PARTITION:                             partitioning.       (line   14)
* partition management:                  partitioning-management.
                                                             (line   13)
* partition pruning:                     partitioning-pruning.
                                                             (line    6)
* partitioning:                          partitioning.       (line   14)
* partitioning information statements:   partitioning-info.  (line    6)
* partitioning keys and primary keys:    partitioning-limitations-partitioning-keys-unique-keys.
                                                             (line    6)
* partitioning keys and unique keys:     partitioning-limitations-partitioning-keys-unique-keys.
                                                             (line    6)
* partitioning, advantages:              partitioning-overview.
                                                             (line  158)
* partitioning, and dates:               partitioning-types. (line   39)
* partitioning, and foreign keys:        partitioning-limitations.
                                                             (line  226)
* partitioning, and FULLTEXT indexes:    partitioning-limitations.
                                                             (line  245)
* partitioning, and key cache:           partitioning-limitations.
                                                             (line  296)
* partitioning, and server SQL mode:     partitioning-limitations.
                                                             (line   50)
* partitioning, and subqueries:          partitioning-limitations.
                                                             (line  286)
* partitioning, and temporary tables <1>: partitioning-limitations-partitioning-keys-unique-keys.
                                                             (line    6)
* partitioning, and temporary tables:    partitioning-limitations.
                                                             (line  255)
* partitioning, by hash:                 partitioning-hash.  (line   10)
* partitioning, by key:                  partitioning-key.   (line    6)
* partitioning, by linear hash:          partitioning-linear-hash.
                                                             (line    6)
* partitioning, by linear key:           partitioning-key.   (line   99)
* partitioning, by list:                 partitioning-list.  (line    6)
* partitioning, by range:                partitioning-range. (line    6)
* partitioning, concepts:                partitioning-overview.
                                                             (line    6)
* partitioning, data type of partitioning key: partitioning-limitations.
                                                             (line  267)
* partitioning, enabling:                partitioning-overview.
                                                             (line   62)
* partitioning, functions supported in partitioning expressions: partitioning-limitations-functions.
                                                             (line    9)
* partitioning, limitations:             partitioning-limitations.
                                                             (line   15)
* Partitioning, maximum number of partitions: partitioning-limitations.
                                                             (line  214)
* partitioning, operators disallowed in partitioning expressions: partitioning-limitations.
                                                             (line   34)
* partitioning, operators supported in partitioning expressions: partitioning-limitations.
                                                             (line   34)
* partitioning, optimization <1>:        partitioning-pruning.
                                                             (line    6)
* partitioning, optimization:            partitioning-info.  (line   59)
* partitioning, resources:               partitioning.       (line   56)
* partitioning, storage engines (limitations): partitioning-limitations-storage-engines.
                                                             (line    6)
* partitioning, subpartitioning:         partitioning-limitations.
                                                             (line  291)
* partitioning, support:                 partitioning-overview.
                                                             (line   62)
* partitioning, support in MySQL Cluster: mysql-cluster-limitations-syntax.
                                                             (line   60)
* partitioning, types:                   partitioning-types. (line   15)
* partitions (MySQL Cluster):            mysql-cluster-nodes-groups.
                                                             (line    6)
* partitions, adding and dropping:       partitioning-management.
                                                             (line   13)
* partitions, analyzing:                 partitioning-maintenance.
                                                             (line    6)
* partitions, checking:                  partitioning-maintenance.
                                                             (line    6)
* PARTITIONS, INFORMATION_SCHEMA table:  partitions-table.   (line    6)
* partitions, managing:                  partitioning-management.
                                                             (line   13)
* partitions, modifying:                 partitioning-management.
                                                             (line   13)
* partitions, optimizing:                partitioning-maintenance.
                                                             (line    6)
* partitions, repairing:                 partitioning-maintenance.
                                                             (line    6)
* partitions, splitting and merging:     partitioning-management.
                                                             (line   13)
* password encryption, reversibility of: encryption-functions.
                                                             (line  260)
* password option:                       connecting.         (line  111)
* password option, mysql:                mysql-command-options.
                                                             (line  310)
* password option, mysql_explain_log:    mysql-convert-table-format.
                                                             (line   37)
* password option, mysql_setpermission:  mysql-setpermission.
                                                             (line   35)
* password option, mysqlaccess:          mysqlaccess.        (line   99)
* password option, mysqladmin:           mysqladmin.         (line  339)
* password option, mysqlbinlog:          mysqlbinlog.        (line  193)
* password option, mysqlcheck:           mysqlcheck.         (line  281)
* password option, mysqld_multi:         mysqld-multi.       (line  130)
* password option, mysqldump:            mysqldump.          (line  635)
* password option, mysqlhotcopy:         mysqlhotcopy.       (line  125)
* password option, mysqlimport:          mysqlimport.        (line  211)
* password option, mysqlmanager:         instance-manager-command-options.
                                                             (line  159)
* password option, mysqlshow:            mysqlshow.          (line  144)
* password option, mysqlslap:            mysqlslap.          (line  289)
* PASSWORD() <1>:                        ignoring-user.      (line   26)
* PASSWORD() <2>:                        encryption-functions.
                                                             (line  249)
* PASSWORD() <3>:                        passwords.          (line    6)
* PASSWORD():                            connection-access.  (line  108)
* password, root user:                   default-privileges. (line    6)
* password-file option, mysqlmanager:    instance-manager-command-options.
                                                             (line  166)
* passwords, for users:                  user-names.         (line    6)
* passwords, forgotten:                  resetting-permissions.
                                                             (line   11)
* passwords, lost:                       resetting-permissions.
                                                             (line   11)
* passwords, resetting:                  resetting-permissions.
                                                             (line   11)
* passwords, security:                   what-privileges.    (line    6)
* passwords, setting <1>:                set-password.       (line    6)
* passwords, setting <2>:                grant.              (line  351)
* passwords, setting:                    passwords.          (line    6)
* PATH environment variable <1>:         invoking-programs.  (line   48)
* PATH environment variable <2>:         environment-variables.
                                                             (line   18)
* PATH environment variable:             installing-binary.  (line  115)
* pattern matching <1>:                  regexp.             (line    6)
* pattern matching:                      pattern-matching.   (line    6)
* performance, benchmarks:               custom-benchmarks.  (line    6)
* performance, disk issues:              disk-issues.        (line   10)
* performance, estimating:               estimating-performance.
                                                             (line    6)
* performance, improving <1>:            replication-faq.    (line   29)
* performance, improving:                data-size.          (line    6)
* PERIOD_ADD():                          date-and-time-functions.
                                                             (line  741)
* PERIOD_DIFF():                         date-and-time-functions.
                                                             (line  750)
* Perl API:                              perl.               (line    6)
* Perl DBI/DBD, installation problems:   perl-support-problems.
                                                             (line    6)
* Perl, installing:                      perl-support.       (line   12)
* Perl, installing on Windows:           activestate-perl.   (line    6)
* permission checks, effect on speed:    query-speed.        (line   31)
* perror:                                programs-overview.  (line  268)
* perror, -ndb option:                   faqs-mysql-cluster. (line  494)
* perror, help option:                   perror.             (line   39)
* perror, ndb option:                    perror.             (line   43)
* perror, silent option:                 perror.             (line   47)
* perror, verbose option:                perror.             (line   51)
* perror, version option:                perror.             (line   56)
* PHP API:                               php.                (line   11)
* PI():                                  mathematical-functions.
                                                             (line  332)
* pid-file option, mysql.server:         mysql-server.       (line   42)
* pid-file option, mysqld:               server-options.     (line 1055)
* pid-file option, mysqld_safe:          mysqld-safe.        (line  192)
* pid-file option, mysqlmanager:         instance-manager-command-options.
                                                             (line  173)
* Ping, thread command:                  thread-commands.    (line   78)
* pipe option:                           connecting.         (line  118)
* pipe option, mysql <1>:                mysqlcheck.         (line  292)
* pipe option, mysql:                    mysql-command-options.
                                                             (line  321)
* pipe option, mysqladmin:               mysqladmin.         (line  350)
* pipe option, mysqldump:                mysqldump.          (line  646)
* pipe option, mysqlimport:              mysqlimport.        (line  222)
* pipe option, mysqlshow:                mysqlshow.          (line  158)
* pipe option, mysqlslap:                mysqlslap.          (line  302)
* PIPES_AS_CONCAT SQL mode:              server-sql-mode.    (line  356)
* plan option, mysqlaccess:              mysqlaccess.        (line  108)
* plugin API:                            plugin-api.         (line   12)
* plugins, adding:                       plugin-api.         (line   12)
* PLUGINS, INFORMATION_SCHEMA table:     plugins-table.      (line    6)
* plugins, installing:                   install-plugin.     (line    6)
* plugins, uninstalling:                 uninstall-plugin.   (line    6)
* POINT data type:                       mysql-spatial-datatypes.
                                                             (line    6)
* point in time recovery:                point-in-time-recovery.
                                                             (line   11)
* Point():                               gis-mysql-specific-functions.
                                                             (line   44)
* PointFromText():                       gis-wkt-functions.  (line   45)
* PointFromWKB():                        gis-wkb-functions.  (line   46)
* PointN():                              linestring-property-functions.
                                                             (line   51)
* PointOnSurface():                      multipolygon-property-functions.
                                                             (line   32)
* PolyFromText():                        gis-wkt-functions.  (line   49)
* PolyFromWKB():                         gis-wkb-functions.  (line   50)
* POLYGON data type:                     mysql-spatial-datatypes.
                                                             (line    6)
* Polygon():                             gis-mysql-specific-functions.
                                                             (line   48)
* PolygonFromText():                     gis-wkt-functions.  (line   49)
* PolygonFromWKB():                      gis-wkb-functions.  (line   50)
* port option:                           connecting.         (line  125)
* port option, mysql:                    mysql-command-options.
                                                             (line  327)
* port option, mysql_setpermission:      mysql-setpermission.
                                                             (line   45)
* port option, mysqladmin:               mysqladmin.         (line  356)
* port option, mysqlbinlog:              mysqlbinlog.        (line  204)
* port option, mysqlcheck:               mysqlcheck.         (line  298)
* port option, mysqld:                   server-options.     (line 1069)
* port option, mysqld_safe:              mysqld-safe.        (line  196)
* port option, mysqldump:                mysqldump.          (line  652)
* port option, mysqlhotcopy:             mysqlhotcopy.       (line  135)
* port option, mysqlimport:              mysqlimport.        (line  228)
* port option, mysqlmanager:             instance-manager-command-options.
                                                             (line  180)
* port option, mysqlshow:                mysqlshow.          (line  164)
* port option, mysqlslap:                mysqlslap.          (line  308)
* port-open-timeout option, mysqld:      server-options.     (line 1084)
* portability:                           portability.        (line    6)
* portability, types:                    other-vendor-data-types.
                                                             (line    6)
* porting, to other systems:             porting.            (line   14)
* PortNumber <1>:                        mysql-cluster-tcp-definition.
                                                             (line   65)
* PortNumber:                            mysql-cluster-mgm-definition.
                                                             (line   28)
* position option, mysqlbinlog:          mysqlbinlog.        (line  208)
* POSITION():                            string-functions.   (line  488)
* post-install, multiple servers:        multiple-servers.   (line   12)
* post-installation, setup and testing:  post-installation.  (line   12)
* post-query option, mysqlslap:          mysqlslap.          (line  312)
* post-system option, mysqlslap:         mysqlslap.          (line  318)
* PostgreSQL compatibility:              extensions-to-ansi. (line  185)
* POSTGRESQL SQL mode:                   server-sql-mode.    (line  486)
* POW():                                 mathematical-functions.
                                                             (line  343)
* POWER():                               mathematical-functions.
                                                             (line  352)
* pre-query option, mysqlslap:           mysqlslap.          (line  324)
* pre-system option, mysqlslap:          mysqlslap.          (line  330)
* precedence, operator:                  operator-precedence.
                                                             (line    6)
* precision math:                        precision-math.     (line   14)
* precision, arithmetic:                 precision-math.     (line   14)
* prefix option, configure:              configure-options.  (line  308)
* PREPARE:                               sql-syntax-prepared-statements.
                                                             (line   10)
* Prepare, thread command:               thread-commands.    (line   82)
* PREPARE, XA transactions:              xa-statements.      (line    6)
* prepared statements <1>:               c-api-prepared-statements.
                                                             (line    6)
* prepared statements:                   sql-syntax-prepared-statements.
                                                             (line   10)
* prepared statements, repreparation:    statement-repreparation.
                                                             (line    6)
* preparing, thread state:               general-thread-states.
                                                             (line  164)
* preserve-schema option, mysqlslap:     mysqlslap.          (line  336)
* preview option, mysqlaccess:           mysqlaccess.        (line  112)
* PRIMARY KEY <1>:                       create-table.       (line  357)
* PRIMARY KEY:                           alter-table.        (line  417)
* primary key, constraint:               constraint-primary-key.
                                                             (line    6)
* primary key, deleting:                 alter-table.        (line  414)
* primary keys, and partitioning keys:   partitioning-limitations-partitioning-keys-unique-keys.
                                                             (line    6)
* print command, mysql:                  mysql-commands.     (line  158)
* print-defaults option:                 option-file-options.
                                                             (line   19)
* print-defaults option, mysqlmanager:   instance-manager-command-options.
                                                             (line  185)
* print-password-line option, mysqlmanager: instance-manager-command-options.
                                                             (line  190)
* privilege information, location:       privileges-provided.
                                                             (line    6)
* privilege system:                      what-privileges.    (line    6)
* privilege system, described:           privileges.         (line    6)
* privilege, changes:                    request-access.     (line  166)
* privileges, access:                    privilege-system.   (line   17)
* privileges, adding:                    adding-users.       (line    6)
* privileges, default:                   default-privileges. (line    6)
* privileges, deleting <1>:              drop-user.          (line    6)
* privileges, deleting:                  removing-users.     (line    6)
* privileges, display:                   show-grants.        (line    6)
* privileges, dropping <1>:              drop-user.          (line    6)
* privileges, dropping:                  removing-users.     (line    6)
* privileges, granting:                  grant.              (line    6)
* privileges, revoking:                  revoke.             (line    6)
* problems, access denied errors:        error-access-denied.
                                                             (line    6)
* problems, common errors:               problems.           (line   17)
* problems, compiling:                   compilation-problems.
                                                             (line    6)
* problems, DATE columns:                using-date.         (line    6)
* problems, date values:                 datetime.           (line  157)
* problems, installing on IBM-AIX:       ibm-aix.            (line    6)
* problems, installing on Solaris:       solaris.            (line   11)
* problems, installing Perl:             perl-support-problems.
                                                             (line    6)
* problems, linking:                     link-errors.        (line    6)
* problems, lost connection errors:      error-lost-connection.
                                                             (line    6)
* problems, ODBC:                        myodbc-support.     (line   14)
* problems, reporting:                   bug-reports.        (line    6)
* problems, starting the server:         starting-server.    (line    6)
* problems, table locking:               table-locking.      (line    6)
* problems, time zone:                   timezone-problems.  (line    6)
* PROCEDURE:                             select.             (line  297)
* procedures, adding:                    adding-procedures.  (line   11)
* procedures, stored <1>:                stored-procedures.  (line   13)
* procedures, stored:                    ansi-diff-triggers. (line    6)
* process management (MySQL Cluster):    mysql-cluster-process-management.
                                                             (line   14)
* process support:                       which-os.           (line    6)
* processes, display:                    show-processlist.   (line    6)
* Processing events from schema table, thread state: mysql-cluster-thread-states.
                                                             (line   14)
* Processing events, thread state:       mysql-cluster-thread-states.
                                                             (line   10)
* processing, arguments:                 udf-arguments.      (line    6)
* PROCESSLIST:                           show-processlist.   (line    6)
* PROCESSLIST, INFORMATION_SCHEMA table: processlist-table.  (line    6)
* Processlist, thread command:           thread-commands.    (line   86)
* program variables, setting:            program-variables.  (line    6)
* program-development utilities:         programs-overview.  (line  246)
* programs, administrative:              programs-overview.  (line  160)
* programs, client <1>:                  building-clients.   (line    6)
* programs, client:                      programs-overview.  (line  119)
* programs, crash-me:                    portability.        (line    6)
* programs, utility:                     programs-overview.  (line  160)
* prompt command, mysql:                 mysql-commands.     (line  162)
* prompt option, mysql:                  mysql-command-options.
                                                             (line  331)
* prompts, meanings:                     entering-queries.   (line  133)
* pronunciation, MySQL:                  what-is-mysql.      (line   87)
* protocol option:                       connecting.         (line  130)
* protocol option, mysql:                mysql-command-options.
                                                             (line  337)
* protocol option, mysqladmin:           mysqladmin.         (line  360)
* protocol option, mysqlbinlog:          mysqlbinlog.        (line  212)
* protocol option, mysqlcheck:           mysqlcheck.         (line  302)
* protocol option, mysqldump:            mysqldump.          (line  656)
* protocol option, mysqlimport:          mysqlimport.        (line  232)
* protocol option, mysqlshow:            mysqlshow.          (line  168)
* protocol option, mysqlslap:            mysqlslap.          (line  342)
* PURGE MASTER LOGS:                     purge-master-logs.  (line    6)
* PURGE STALE SESSIONS:                  mysql-cluster-start-phases.
                                                             (line   78)
* Purging old relay logs, thread state:  general-thread-states.
                                                             (line  168)
* Python API:                            python.             (line    6)
* QUARTER():                             date-and-time-functions.
                                                             (line  759)
* queries, entering:                     entering-queries.   (line    6)
* queries, estimating performance:       estimating-performance.
                                                             (line    6)
* queries, examples:                     examples.           (line   18)
* queries, speed of:                     query-speed.        (line   31)
* queries, Twin Studies project:         twin.               (line   11)
* Query Cache:                           query-cache.        (line   13)
* query end, thread state:               general-thread-states.
                                                             (line  172)
* query option, mysqlslap:               mysqlslap.          (line  349)
* query option, ndb_config:              mysql-cluster-utilities-ndb-config.
                                                             (line   47)
* Query, thread command:                 thread-commands.    (line   90)
* questions:                             mysqladmin.         (line  186)
* questions, answering:                  mailing-list-use.   (line    6)
* Queueing master event to the relay log, thread state: slave-io-thread-states.
                                                             (line   56)
* quick option, myisamchk:               myisamchk-repair-options.
                                                             (line   64)
* quick option, mysql:                   mysql-command-options.
                                                             (line  344)
* quick option, mysqlcheck:              mysqlcheck.         (line  309)
* quick option, mysqldump:               mysqldump.          (line  663)
* quiet option, mysqlhotcopy:            mysqlhotcopy.       (line  139)
* QUIT command (MySQL Cluster):          mysql-cluster-mgm-client-commands.
                                                             (line  115)
* quit command, mysql:                   mysql-commands.     (line  171)
* Quit, thread command:                  thread-commands.    (line   94)
* QUOTE():                               string-functions.   (line  492)
* quote-names option, mysqldump:         mysqldump.          (line  670)
* quotes, in strings:                    string-syntax.      (line   85)
* quoting:                               string-syntax.      (line  133)
* quoting binary data:                   string-syntax.      (line  123)
* quoting of identifiers:                identifiers.        (line   20)
* RADIANS():                             mathematical-functions.
                                                             (line  356)
* RAND():                                mathematical-functions.
                                                             (line  364)
* range join type, optimizer:            using-explain.      (line  230)
* range partitioning:                    partitioning-range. (line    6)
* range partitions, adding and dropping: partitioning-management-range-list.
                                                             (line    6)
* range partitions, managing:            partitioning-management-range-list.
                                                             (line    6)
* raw option, mysql:                     mysql-command-options.
                                                             (line  350)
* re-creating, grant tables:             mysql-install-db-problems.
                                                             (line   95)
* read-from-remote-server option, mysqlbinlog: mysqlbinlog.  (line  219)
* read-only option, myisamchk:           myisamchk-check-options.
                                                             (line   49)
* read-only option, mysqld:              replication-options.
                                                             (line  251)
* read_buffer_size myisamchk variable:   myisamchk-general-options.
                                                             (line   45)
* Reading event from the relay log, thread state: slave-sql-thread-states.
                                                             (line   13)
* Reading from net, thread state:        general-thread-states.
                                                             (line  177)
* Reading master dump table data, thread state: slave-connection-thread-states.
                                                             (line   27)
* REAL data type:                        numeric-type-overview.
                                                             (line  205)
* REAL_AS_FLOAT SQL mode:                server-sql-mode.    (line  361)
* RealtimeScheduler:                     mysql-cluster-ndbd-definition.
                                                             (line 1599)
* Rebuilding the index on master dump table, thread state: slave-connection-thread-states.
                                                             (line   31)
* ReceiveBufferMemory:                   mysql-cluster-tcp-definition.
                                                             (line   71)
* reconfiguring:                         compilation-problems.
                                                             (line    6)
* reconnect option, mysql:               mysql-command-options.
                                                             (line  381)
* Reconnecting after a failed binlog dump request, thread state: slave-io-thread-states.
                                                             (line   44)
* Reconnecting after a failed master event read, thread state: slave-io-thread-states.
                                                             (line   68)
* record_log_pos option, mysqlhotcopy:   mysqlhotcopy.       (line  143)
* recover option, myisamchk:             myisamchk-repair-options.
                                                             (line   70)
* RECOVER, XA transactions:              xa-statements.      (line    6)
* recovery, from crash:                  crash-recovery.     (line    6)
* recovery, point in time:               point-in-time-recovery.
                                                             (line   11)
* RedoBuffer:                            mysql-cluster-ndbd-definition.
                                                             (line 1353)
* reducing, data size:                   data-size.          (line    6)
* ref join type, optimizer:              using-explain.      (line  164)
* ref_or_null:                           is-null-optimization.
                                                             (line    6)
* ref_or_null join type, optimizer:      using-explain.      (line  191)
* references:                            alter-table.        (line  490)
* REFERENTIAL_CONSTRAINTS, INFORMATION_SCHEMA table: referential-constraints-table.
                                                             (line    6)
* Refresh, thread command:               thread-commands.    (line   98)
* REGEXP:                                string-comparison-functions.
                                                             (line  148)
* REGEXP operator:                       regexp.             (line    6)
* regexp option, mysql_find_rows:        mysql-find-rows.    (line   31)
* regexp option, mysqlhotcopy:           mysqlhotcopy.       (line  148)
* Register Slave, thread command:        thread-commands.    (line  103)
* Registering slave on master, thread state: slave-io-thread-states.
                                                             (line   24)
* regular expression syntax:             regexp.             (line    6)
* rehash command, mysql:                 mysql-commands.     (line  175)
* Related():                             functions-that-test-spatial-relationships-between-geometries.
                                                             (line   69)
* relational databases, defined:         what-is-mysql.      (line   42)
* relative option, mysqladmin:           mysqladmin.         (line  367)
* relay-log option, mysqld:              replication-options.
                                                             (line  258)
* relay-log-index option, mysqld:        replication-options.
                                                             (line  269)
* relay-log-info-file option, mysqld:    replication-options.
                                                             (line  275)
* relay-log-purge option, mysqld:        replication-options.
                                                             (line  281)
* relay-log-space-limit option, mysqld:  replication-options.
                                                             (line  288)
* release numbers:                       which-version.      (line   19)
* RELEASE SAVEPOINT:                     savepoints.         (line    6)
* RELEASE_LOCK():                        miscellaneous-functions.
                                                             (line  173)
* releases, naming scheme:               choosing-version.   (line   55)
* releases, testing:                     choosing-version.   (line  122)
* releases, updating:                    many-versions.      (line    6)
* relnotes option, mysqlaccess:          mysqlaccess.        (line  117)
* remote administration (MySQL Cluster), and security issues: mysql-cluster-security-networking-issues.
                                                             (line  189)
* remove option, mysqlmanager:           instance-manager-command-options.
                                                             (line  198)
* Removing duplicates, thread state:     general-thread-states.
                                                             (line  181)
* removing tmp table, thread state:      general-thread-states.
                                                             (line  188)
* RENAME DATABASE:                       rename-database.    (line    6)
* rename result table, thread state:     general-thread-states.
                                                             (line  198)
* RENAME TABLE:                          rename-table.       (line    6)
* RENAME USER:                           rename-user.        (line    6)
* rename, thread state:                  general-thread-states.
                                                             (line  194)
* renaming user accounts:                rename-user.        (line    6)
* Reopen tables, thread state:           general-thread-states.
                                                             (line  203)
* reordering, columns:                   change-column-order.
                                                             (line    6)
* Repair by sorting, thread state:       general-thread-states.
                                                             (line  209)
* Repair done, thread state:             general-thread-states.
                                                             (line  213)
* repair option, mysqlcheck:             mysqlcheck.         (line  318)
* repair options, myisamchk:             myisamchk-repair-options.
                                                             (line    6)
* REPAIR TABLE:                          repair-table.       (line    6)
* Repair with keycache, thread state:    general-thread-states.
                                                             (line  218)
* repairing, tables:                     repair.             (line    6)
* REPEAT:                                repeat-statement.   (line    6)
* REPEAT():                              string-functions.   (line  506)
* REPLACE:                               replace.            (line    6)
* replace:                               programs-overview.  (line  273)
* replace option, mysqldump:             mysqldump.          (line  679)
* replace option, mysqlimport:           mysqlimport.        (line  239)
* REPLACE():                             string-functions.   (line  515)
* replicas (MySQL Cluster):              mysql-cluster-nodes-groups.
                                                             (line    6)
* replicate-do-db option, mysqld:        replication-options.
                                                             (line  309)
* replicate-do-table option, mysqld:     replication-options.
                                                             (line  402)
* replicate-ignore-db option, mysqld:    replication-options.
                                                             (line  409)
* replicate-ignore-table option, mysqld: replication-options.
                                                             (line  456)
* replicate-rewrite-db option, mysqld:   replication-options.
                                                             (line  465)
* replicate-same-server-id option, mysqld: replication-options.
                                                             (line  484)
* replicate-wild-do-table option, mysqld: replication-options.
                                                             (line  498)
* replicate-wild-ignore-table option, mysqld: replication-options.
                                                             (line  530)
* replication:                           replication.        (line   13)
* replication implementation:            replication-implementation.
                                                             (line   12)
* replication limitations:               replication-features.
                                                             (line   33)
* replication master, thread states:     master-thread-states.
                                                             (line    6)
* replication masters, statements:       replication-master-sql.
                                                             (line   12)
* replication options:                   replication-features.
                                                             (line   33)
* replication slave, thread states <1>:  slave-connection-thread-states.
                                                             (line    6)
* replication slave, thread states <2>:  slave-sql-thread-states.
                                                             (line    6)
* replication slave, thread states:      slave-io-thread-states.
                                                             (line    6)
* replication slaves, statements:        replication-slave-sql.
                                                             (line   17)
* replication, asynchronous:             mysql-cluster-replication.
                                                             (line   19)
* replication, attribute promotion:      replication-features-different-data-types.
                                                             (line   14)
* replication, circular:                 mysql-cluster-replication-issues.
                                                             (line   56)
* replication, in MySQL Cluster:         mysql-cluster-replication.
                                                             (line   19)
* REPORT command (MySQL Cluster):        mysql-cluster-mgm-client-commands.
                                                             (line   83)
* report-host option, mysqld:            replication-options.
                                                             (line  547)
* report-password option, mysqld:        replication-options.
                                                             (line  566)
* report-port option, mysqld:            replication-options.
                                                             (line  558)
* report-user option, mysqld:            replication-options.
                                                             (line  573)
* reporting, bugs:                       bug-reports.        (line    6)
* reporting, Connector/NET problems:     connect-net-support.
                                                             (line   12)
* reporting, Connector/ODBC problems:    myodbc-support.     (line   14)
* reporting, errors <1>:                 bug-reports.        (line    6)
* reporting, errors:                     introduction.       (line   77)
* Requesting binlog dump, thread state:  slave-io-thread-states.
                                                             (line   29)
* REQUIRE GRANT option:                  grant.              (line  439)
* reschedule, thread state:              delayed-insert-thread-states.
                                                             (line   77)
* reserved words:                        reserved-words.     (line    6)
* RESET MASTER:                          reset-master.       (line    6)
* RESET SLAVE:                           reset-slave.        (line    6)
* Reset stmt, thread command:            thread-commands.    (line  107)
* reset-slave.pl:                        mysql-cluster-replication-auto-sync.
                                                             (line   11)
* resetmaster option, mysqlhotcopy:      mysqlhotcopy.       (line  153)
* resetslave option, mysqlhotcopy:       mysqlhotcopy.       (line  157)
* resolve_stack_dump:                    programs-overview.  (line  261)
* resolve_stack_dump, help option:       resolve-stack-dump. (line   20)
* resolve_stack_dump, numeric-dump-file option: resolve-stack-dump.
                                                             (line   24)
* resolve_stack_dump, symbols-file option: resolve-stack-dump.
                                                             (line   28)
* resolve_stack_dump, version option:    resolve-stack-dump. (line   32)
* resolveip:                             programs-overview.  (line  278)
* resolveip, help option:                resolveip.          (line   15)
* resolveip, silent option:              resolveip.          (line   19)
* resolveip, version option:             resolveip.          (line   23)
* RESTART command (MySQL Cluster):       mysql-cluster-mgm-client-commands.
                                                             (line   56)
* restarting, the server:                unix-post-installation.
                                                             (line  164)
* RestartOnErrorInsert:                  mysql-cluster-ndbd-definition.
                                                             (line  869)
* RESTORE TABLE:                         restore-table.      (line    6)
* restoring from backups, in MySQL Cluster replication: mysql-cluster-replication-backups.
                                                             (line   10)
* restrictions, events:                  routine-restrictions.
                                                             (line    6)
* restrictions, server-side cursors:     cursor-restrictions.
                                                             (line    6)
* restrictions, stored routines:         routine-restrictions.
                                                             (line    6)
* restrictions, subqueries:              subquery-restrictions.
                                                             (line    6)
* restrictions, triggers:                routine-restrictions.
                                                             (line    6)
* restrictions, views:                   view-restrictions.  (line    6)
* result-file option, mysqlbinlog:       mysqlbinlog.        (line  230)
* result-file option, mysqldump:         mysqldump.          (line  684)
* retrieving, data from tables:          retrieving-data.    (line   18)
* RETURN:                                return.             (line    6)
* return (\r) <1>:                       load-data.          (line  415)
* return (\r):                           string-syntax.      (line   53)
* return values, UDFs:                   udf-return-values.  (line    6)
* REVERSE():                             string-functions.   (line  526)
* REVOKE:                                revoke.             (line    6)
* revoking, privileges:                  revoke.             (line    6)
* rhost option, mysqlaccess:             mysqlaccess.        (line  121)
* RIGHT JOIN:                            join.               (line    6)
* RIGHT OUTER JOIN:                      join.               (line    6)
* RIGHT():                               string-functions.   (line  535)
* RLIKE:                                 string-comparison-functions.
                                                             (line  148)
* ROLLBACK <1>:                          commit.             (line    6)
* ROLLBACK:                              ansi-diff-transactions.
                                                             (line    6)
* rollback option, mysqlaccess:          mysqlaccess.        (line  125)
* ROLLBACK TO SAVEPOINT:                 savepoints.         (line    6)
* ROLLBACK, XA transactions:             xa-statements.      (line    6)
* Rolling back, thread state:            general-thread-states.
                                                             (line  223)
* rolling restart (MySQL Cluster):       mysql-cluster-rolling-restart.
                                                             (line    6)
* rolling upgrades and downgrades (MySQL Cluster): mysql-cluster-rolling-restart.
                                                             (line    6)
* ROLLUP:                                group-by-modifiers. (line    6)
* root password:                         default-privileges. (line    6)
* root user, password resetting:         resetting-permissions.
                                                             (line   11)
* ROUND():                               mathematical-functions.
                                                             (line  419)
* rounding:                              precision-math.     (line   14)
* rounding errors:                       numeric-type-overview.
                                                             (line  139)
* routines option, mysqldump:            mysqldump.          (line  692)
* ROUTINES, INFORMATION_SCHEMA table:    routines-table.     (line    6)
* ROW:                                   row-subqueries.     (line    6)
* row subqueries:                        row-subqueries.     (line    6)
* row-level locking:                     internal-locking.   (line    6)
* ROW_COUNT():                           information-functions.
                                                             (line  428)
* rowid option, ndb_select_all:          mysql-cluster-utilities-ndb-select-all.
                                                             (line   60)
* rows option, mysql_find_rows:          mysql-find-rows.    (line   35)
* rows option, ndb_config:               mysql-cluster-utilities-ndb-config.
                                                             (line  102)
* rows, counting:                        counting-rows.      (line    6)
* rows, deleting:                        deleting-from-related-tables.
                                                             (line    6)
* rows, locking:                         ansi-diff-transactions.
                                                             (line  168)
* rows, matching problems:               no-matching-rows.   (line    6)
* rows, selecting:                       selecting-rows.     (line    6)
* rows, sorting:                         sorting-rows.       (line    6)
* RPAD():                                string-functions.   (line  545)
* RPM file:                              linux-rpm.          (line    6)
* RPM Package Manager:                   linux-rpm.          (line    6)
* RTRIM():                               string-functions.   (line  558)
* RTS-threads:                           rts-threads.        (line    6)
* run-as-service option, mysqlmanager:   instance-manager-command-options.
                                                             (line  204)
* running configure after prior invocation: compilation-problems.
                                                             (line   15)
* running, ANSI mode:                    ansi-mode.          (line    6)
* running, batch mode:                   batch-mode.         (line    6)
* running, multiple servers:             multiple-servers.   (line   12)
* running, queries:                      entering-queries.   (line    6)
* safe-mode option, mysqld:              server-options.     (line 1097)
* safe-recover option, myisamchk:        myisamchk-repair-options.
                                                             (line   83)
* safe-show-database option, mysqld <1>: privileges-options. (line   57)
* safe-show-database option, mysqld:     server-options.     (line 1103)
* safe-updates option:                   safe-updates.       (line    6)
* safe-updates option, mysql:            mysql-command-options.
                                                             (line  388)
* safe-user-create option, mysqld <1>:   privileges-options. (line   67)
* safe-user-create option, mysqld:       server-options.     (line 1116)
* Sakila:                                history.            (line    6)
* SAVEPOINT:                             savepoints.         (line    6)
* Saving state, thread state:            general-thread-states.
                                                             (line  227)
* scale, arithmetic:                     precision-math.     (line   14)
* SchedulerExecutionTimer:               mysql-cluster-ndbd-definition.
                                                             (line 1606)
* SchedulerSpinTimer:                    mysql-cluster-ndbd-definition.
                                                             (line 1613)
* SCHEMA():                              information-functions.
                                                             (line  465)
* schema, altering:                      alter-database.     (line    6)
* schema, creating:                      create-database.    (line    6)
* schema, deleting:                      drop-database.      (line    6)
* SCHEMA_PRIVILEGES, INFORMATION_SCHEMA table: schema-privileges-table.
                                                             (line    6)
* SCHEMATA, INFORMATION_SCHEMA table:    schemata-table.     (line    6)
* SCI (Scalable Coherent Interface) <1>: mysql-cluster-sci-sockets.
                                                             (line    6)
* SCI (Scalable Coherent Interface):     mysql-cluster-sci-definition.
                                                             (line    6)
* script files:                          batch-mode.         (line    6)
* scripts, mysql_install_db:             mysql-install-db-problems.
                                                             (line    6)
* scripts, mysqlbug:                     bug-reports.        (line  328)
* Searching rows for update, thread state: general-thread-states.
                                                             (line  234)
* searching, and case sensitivity:       case-sensitivity.   (line    6)
* searching, full-text:                  fulltext-search.    (line   15)
* searching, MySQL Web pages:            bug-reports.        (line    6)
* searching, two keys:                   searching-on-two-keys.
                                                             (line    6)
* SEC_TO_TIME():                         date-and-time-functions.
                                                             (line  773)
* SECOND():                              date-and-time-functions.
                                                             (line  766)
* secure-auth option, mysql:             mysql-command-options.
                                                             (line  396)
* secure-auth option, mysqld <1>:        privileges-options. (line   82)
* secure-auth option, mysqld:            server-options.     (line 1137)
* secure-file-priv option, mysqld <1>:   privileges-options. (line   91)
* secure-file-priv option, mysqld:       server-options.     (line 1151)
* securing a MySQL Cluster:              mysql-cluster-security-mysql-security-procedures.
                                                             (line    6)
* security system:                       privilege-system.   (line   17)
* security, against attackers:           security-against-attack.
                                                             (line    6)
* security, and malicious SQL statements: mysql-cluster-security-mysql-privileges.
                                                             (line   78)
* security, and NDB utilities:           mysql-cluster-security-mysql-security-procedures.
                                                             (line   74)
* SELECT INTO:                           select-into-statement.
                                                             (line    6)
* SELECT INTO TABLE:                     ansi-diff-select-into-table.
                                                             (line    6)
* SELECT speed:                          select-speed.       (line    6)
* SELECT, LIMIT:                         select.             (line   12)
* SELECT, optimizing <1>:                explain.            (line    6)
* SELECT, optimizing:                    using-explain.      (line    6)
* SELECT, Query Cache:                   query-cache.        (line   13)
* select_limit variable:                 mysql-command-options.
                                                             (line  561)
* selecting, databases:                  creating-database.  (line    6)
* SendBufferMemory:                      mysql-cluster-tcp-definition.
                                                             (line   36)
* Sending binlog event to slave, thread state: master-thread-states.
                                                             (line   11)
* SendLimit:                             mysql-cluster-sci-definition.
                                                             (line   61)
* SendSignalId <1>:                      mysql-cluster-sci-definition.
                                                             (line   69)
* SendSignalId <2>:                      mysql-cluster-shm-definition.
                                                             (line   41)
* SendSignalId:                          mysql-cluster-tcp-definition.
                                                             (line   48)
* SEQUENCE:                              example-auto-increment.
                                                             (line    6)
* sequence emulation:                    information-functions.
                                                             (line  392)
* sequences:                             example-auto-increment.
                                                             (line    6)
* SERIAL:                                numeric-type-overview.
                                                             (line  127)
* SERIAL DEFAULT VALUE:                  data-type-defaults. (line   69)
* server variables <1>:                  show-variables.     (line    6)
* server variables:                      server-system-variables.
                                                             (line    6)
* server, connecting <1>:                connecting.         (line    6)
* server, connecting:                    connecting-disconnecting.
                                                             (line    6)
* server, debugging:                     debugging-server.   (line   16)
* server, disconnecting:                 connecting-disconnecting.
                                                             (line    6)
* server, restart:                       unix-post-installation.
                                                             (line  164)
* server, shutdown:                      unix-post-installation.
                                                             (line  157)
* server, signal handling:               server-signal-response.
                                                             (line    6)
* server, starting:                      unix-post-installation.
                                                             (line   46)
* server, starting and stopping:         automatic-start.    (line    6)
* server, starting problems:             starting-server.    (line    6)
* server-id option, mysqlbinlog:         mysqlbinlog.        (line  234)
* server-side cursor restrictions:       cursor-restrictions.
                                                             (line    6)
* ServerPort:                            mysql-cluster-ndbd-definition.
                                                             (line   54)
* servers, multiple:                     multiple-servers.   (line   12)
* service-startup-timeout option, mysql.server: mysql-server.
                                                             (line   47)
* session server variables:              server-session-variables.
                                                             (line    6)
* session system variables:              server-session-variables.
                                                             (line    6)
* session variables, server:             server-session-variables.
                                                             (line    6)
* session variables, system:             server-session-variables.
                                                             (line    6)
* SESSION_STATUS, INFORMATION_SCHEMA table: status-table.    (line    6)
* SESSION_USER():                        information-functions.
                                                             (line  469)
* SESSION_VARIABLES, INFORMATION_SCHEMA table: variables-table.
                                                             (line    6)
* SET <1>:                               set-statement.      (line    6)
* SET:                                   set-option.         (line    6)
* SET data type <1>:                     set.                (line    6)
* SET data type:                         string-type-overview.
                                                             (line  229)
* SET GLOBAL SQL_SLAVE_SKIP_COUNTER:     set-global-sql-slave-skip-counter.
                                                             (line    6)
* SET OPTION:                            set-option.         (line    6)
* Set option, thread command:            thread-commands.    (line  111)
* SET PASSWORD:                          set-password.       (line    6)
* SET PASSWORD statement:                passwords.          (line    6)
* SET SQL_LOG_BIN:                       set-sql-log-bin.    (line    6)
* SET TRANSACTION:                       set-transaction.    (line    6)
* SET, AUTOCOMMIT:                       server-session-variables.
                                                             (line   23)
* SET, BIG_TABLES:                       server-session-variables.
                                                             (line   23)
* SET, CHARACTER SET <1>:                set-option.         (line  153)
* SET, CHARACTER SET:                    charset-connection. (line    6)
* SET, FOREIGN_KEY_CHECKS:               server-session-variables.
                                                             (line   23)
* SET, IDENTITY:                         server-session-variables.
                                                             (line   23)
* SET, INSERT_ID:                        server-session-variables.
                                                             (line   23)
* SET, LAST_INSERT_ID:                   server-session-variables.
                                                             (line   23)
* SET, NAMES <1>:                        set-option.         (line  169)
* SET, NAMES:                            charset-connection. (line    6)
* SET, ONE_SHOT:                         set-option.         (line  185)
* SET, size:                             storage-requirements.
                                                             (line  198)
* SET, SQL_AUTO_IS_NULL:                 server-session-variables.
                                                             (line   23)
* SET, SQL_BIG_SELECTS:                  server-session-variables.
                                                             (line   23)
* SET, SQL_BUFFER_SELECT:                server-session-variables.
                                                             (line   23)
* SET, SQL_LOG_BIN:                      server-session-variables.
                                                             (line   23)
* SET, SQL_LOG_OFF:                      server-session-variables.
                                                             (line   23)
* SET, SQL_LOG_UPDATE:                   server-session-variables.
                                                             (line   23)
* SET, SQL_NOTES:                        server-session-variables.
                                                             (line   23)
* SET, SQL_QUOTE_SHOW_CREATE:            server-session-variables.
                                                             (line   23)
* SET, SQL_SAFE_UPDATES:                 server-session-variables.
                                                             (line   23)
* SET, SQL_SELECT_LIMIT:                 server-session-variables.
                                                             (line   23)
* SET, SQL_WARNINGS:                     server-session-variables.
                                                             (line   23)
* SET, TIMESTAMP:                        server-session-variables.
                                                             (line   23)
* SET, UNIQUE_CHECKS:                    server-session-variables.
                                                             (line   23)
* set-auto-increment[ option, myisamchk: myisamchk-other-options.
                                                             (line   32)
* set-character-set option, myisamchk:   myisamchk-repair-options.
                                                             (line   96)
* set-charset option, mysqlbinlog:       mysqlbinlog.        (line  239)
* set-charset option, mysqldump:         mysqldump.          (line  717)
* set-collation option, myisamchk:       myisamchk-repair-options.
                                                             (line  101)
* setting passwords:                     set-password.       (line    6)
* setting program variables:             program-variables.  (line    6)
* setting, passwords:                    passwords.          (line    6)
* setup, post-installation:              post-installation.  (line   12)
* setup, thread state:                   general-thread-states.
                                                             (line  245)
* SHA():                                 encryption-functions.
                                                             (line  274)
* SHA1():                                encryption-functions.
                                                             (line  274)
* shared memory transporter:             mysql-cluster-shm-definition.
                                                             (line    6)
* shared-memory option, mysqld:          server-options.     (line 1168)
* shared-memory-base-name option:        connecting.         (line  160)
* shared-memory-base-name option, mysqld: server-options.    (line 1173)
* SharedBufferSize:                      mysql-cluster-sci-definition.
                                                             (line   52)
* SharedGlobalMemory:                    mysql-cluster-disk-data-parameters.
                                                             (line   17)
* shell syntax:                          manual-conventions. (line  111)
* ShmKey:                                mysql-cluster-shm-definition.
                                                             (line   28)
* ShmSize:                               mysql-cluster-shm-definition.
                                                             (line   34)
* short-form option, mysqlbinlog:        mysqlbinlog.        (line  245)
* SHOW AUTHORS <1>:                      show-authors.       (line    6)
* SHOW AUTHORS:                          show.               (line   46)
* SHOW BINARY LOGS:                      show-binary-logs.   (line    6)
* SHOW BINLOG EVENTS <1>:                show-binlog-events. (line    6)
* SHOW BINLOG EVENTS:                    show.               (line   90)
* SHOW CHARACTER SET <1>:                show-character-set. (line    6)
* SHOW CHARACTER SET:                    show.               (line   46)
* SHOW COLLATION <1>:                    show-collation.     (line    6)
* SHOW COLLATION:                        show.               (line   46)
* SHOW COLUMNS <1>:                      show-columns.       (line    6)
* SHOW COLUMNS:                          show.               (line   46)
* SHOW command (MySQL Cluster):          mysql-cluster-mgm-client-commands.
                                                             (line   24)
* SHOW CONTRIBUTORS <1>:                 show-contributors.  (line    6)
* SHOW CONTRIBUTORS:                     show.               (line   46)
* SHOW CREATE DATABASE <1>:              show-create-database.
                                                             (line    6)
* SHOW CREATE DATABASE:                  show.               (line   46)
* SHOW CREATE EVENT:                     show.               (line   46)
* SHOW CREATE FUNCTION <1>:              show-create-procedure.
                                                             (line    6)
* SHOW CREATE FUNCTION:                  show.               (line   46)
* SHOW CREATE PROCEDURE <1>:             show-create-procedure.
                                                             (line    6)
* SHOW CREATE PROCEDURE:                 show.               (line   46)
* SHOW CREATE SCHEMA <1>:                show-create-database.
                                                             (line    6)
* SHOW CREATE SCHEMA:                    show.               (line   46)
* SHOW CREATE TABLE <1>:                 show-create-table.  (line    6)
* SHOW CREATE TABLE:                     show.               (line   46)
* SHOW CREATE TRIGGER <1>:               show-create-trigger.
                                                             (line    6)
* SHOW CREATE TRIGGER:                   show.               (line   46)
* SHOW CREATE VIEW <1>:                  show-create-view.   (line    6)
* SHOW CREATE VIEW:                      show.               (line   46)
* SHOW DATABASES <1>:                    show-databases.     (line    6)
* SHOW DATABASES:                        show.               (line   46)
* SHOW ENGINE <1>:                       show-engine.        (line    6)
* SHOW ENGINE:                           show.               (line   46)
* SHOW ENGINE INNODB STATUS:             show-engine.        (line    6)
* SHOW ENGINE NDB STATUS <1>:            mysql-cluster-sql-statements.
                                                             (line   10)
* SHOW ENGINE NDB STATUS:                show-engine.        (line    6)
* SHOW ENGINE NDBCLUSTER STATUS <1>:     mysql-cluster-sql-statements.
                                                             (line   10)
* SHOW ENGINE NDBCLUSTER STATUS:         show-engine.        (line    6)
* SHOW ENGINE, used with MySQL Cluster:  mysql-cluster-sql-statements.
                                                             (line   10)
* SHOW ENGINES <1>:                      show-engines.       (line    6)
* SHOW ENGINES:                          show.               (line   46)
* SHOW ENGINES, used with MySQL Cluster: mysql-cluster-sql-statements.
                                                             (line   19)
* SHOW ERRORS <1>:                       show-errors.        (line    6)
* SHOW ERRORS:                           show.               (line   46)
* SHOW ERRORS, and MySQL Cluster:        faqs-mysql-cluster. (line  489)
* SHOW EVENTS:                           show.               (line   46)
* SHOW extensions:                       extended-show.      (line    6)
* SHOW FIELDS <1>:                       show-columns.       (line   92)
* SHOW FIELDS:                           show.               (line   46)
* SHOW FUNCTION CODE <1>:                show-procedure-code.
                                                             (line    6)
* SHOW FUNCTION CODE:                    show.               (line   46)
* SHOW FUNCTION STATUS <1>:              show-procedure-status.
                                                             (line    6)
* SHOW FUNCTION STATUS:                  show.               (line   46)
* SHOW GRANTS <1>:                       show-grants.        (line    6)
* SHOW GRANTS:                           show.               (line   46)
* SHOW INDEX <1>:                        show-index.         (line    6)
* SHOW INDEX:                            show.               (line   46)
* SHOW INNODB STATUS:                    show.               (line   46)
* SHOW KEYS <1>:                         show-index.         (line    6)
* SHOW KEYS:                             show.               (line   46)
* SHOW MASTER LOGS <1>:                  show-binary-logs.   (line    6)
* SHOW MASTER LOGS:                      show.               (line   90)
* SHOW MASTER STATUS <1>:                show-master-status. (line    6)
* SHOW MASTER STATUS:                    show.               (line   90)
* SHOW OPEN TABLES <1>:                  show-open-tables.   (line    6)
* SHOW OPEN TABLES:                      show.               (line   46)
* SHOW PLUGINS <1>:                      show-plugins.       (line    6)
* SHOW PLUGINS:                          show.               (line   46)
* SHOW PRIVILEGES <1>:                   show-privileges.    (line    6)
* SHOW PRIVILEGES:                       show.               (line   46)
* SHOW PROCEDURE CODE <1>:               show-procedure-code.
                                                             (line    6)
* SHOW PROCEDURE CODE:                   show.               (line   46)
* SHOW PROCEDURE STATUS <1>:             show-procedure-status.
                                                             (line    6)
* SHOW PROCEDURE STATUS:                 show.               (line   46)
* SHOW PROCESSLIST <1>:                  show-processlist.   (line    6)
* SHOW PROCESSLIST:                      show.               (line   46)
* SHOW SCHEDULER STATUS <1>:             events-status-info. (line    6)
* SHOW SCHEDULER STATUS:                 show.               (line   46)
* SHOW SCHEMAS <1>:                      show-databases.     (line    6)
* SHOW SCHEMAS:                          show.               (line   46)
* SHOW SLAVE HOSTS <1>:                  show-slave-hosts.   (line    6)
* SHOW SLAVE HOSTS:                      show.               (line   90)
* SHOW SLAVE STATUS <1>:                 show-slave-status.  (line    6)
* SHOW SLAVE STATUS:                     show.               (line   90)
* SHOW STATUS:                           show.               (line   46)
* SHOW STATUS, used with MySQL Cluster:  mysql-cluster-sql-statements.
                                                             (line  121)
* SHOW STORAGE ENGINES:                  show-engines.       (line    6)
* SHOW TABLE STATUS:                     show.               (line   46)
* SHOW TABLE TYPES <1>:                  show-engines.       (line    6)
* SHOW TABLE TYPES:                      show.               (line   46)
* SHOW TABLES <1>:                       show-tables.        (line    6)
* SHOW TABLES:                           show.               (line   46)
* SHOW TRIGGERS <1>:                     show-triggers.      (line    6)
* SHOW TRIGGERS:                         show.               (line   46)
* SHOW VARIABLES:                        show.               (line   46)
* SHOW VARIABLES, used with MySQL Cluster: mysql-cluster-sql-statements.
                                                             (line   55)
* SHOW WARNINGS <1>:                     show-warnings.      (line    6)
* SHOW WARNINGS:                         show.               (line   46)
* SHOW WARNINGS, and MySQL Cluster:      faqs-mysql-cluster. (line  489)
* SHOW with WHERE <1>:                   extended-show.      (line    6)
* SHOW with WHERE:                       information-schema. (line   36)
* SHOW, in MySQL Cluster management client: mysql-cluster-quick.
                                                             (line  139)
* show-slave-auth-info option, mysqld:   replication-options.
                                                             (line  580)
* show-table-type option, mysqlshow:     mysqlshow.          (line  175)
* show-warnings option, mysql:           mysql-command-options.
                                                             (line  408)
* SHUTDOWN command (MySQL Cluster):      mysql-cluster-mgm-client-commands.
                                                             (line  121)
* Shutdown, thread command:              thread-commands.    (line  116)
* shutdown_timeout variable:             mysqladmin.         (line  426)
* shutting down, the server:             unix-post-installation.
                                                             (line  157)
* Shutting down, thread state:           mysql-cluster-thread-states.
                                                             (line   18)
* sigint-ignore option, mysql:           mysql-command-options.
                                                             (line  413)
* SIGN():                                mathematical-functions.
                                                             (line  479)
* signals, server response:              server-signal-response.
                                                             (line    6)
* silent column changes:                 silent-column-changes.
                                                             (line    6)
* silent option, myisamchk:              myisamchk-general-options.
                                                             (line   20)
* silent option, myisampack:             myisampack.         (line   89)
* silent option, mysql:                  mysql-command-options.
                                                             (line  417)
* silent option, mysqladmin:             mysqladmin.         (line  373)
* silent option, mysqlcheck:             mysqlcheck.         (line  323)
* silent option, mysqld_multi:           mysqld-multi.       (line  136)
* silent option, mysqlimport:            mysqlimport.        (line  249)
* silent option, mysqlslap:              mysqlslap.          (line  354)
* silent option, perror:                 perror.             (line   47)
* silent option, resolveip:              resolveip.          (line   19)
* SIN():                                 mathematical-functions.
                                                             (line  491)
* single quote (\'):                     string-syntax.      (line   49)
* single user mode (MySQL Cluster) <1>:  mysql-cluster-single-user-mode.
                                                             (line    6)
* single user mode (MySQL Cluster):      mysql-cluster-mgm-client-commands.
                                                             (line   99)
* single user mode (MySQL Cluster), and ndb_restore: mysql-cluster-restore.
                                                             (line   17)
* single-transaction option, mysqldump:  mysqldump.          (line  723)
* size of tables:                        full-table.         (line    6)
* sizes, display:                        data-types.         (line   31)
* skip-column-names option, mysql:       mysql-command-options.
                                                             (line  426)
* skip-comments option, mysqldump:       mysqldump.          (line  758)
* skip-concurrent-insert option, mysqld: server-options.     (line 1179)
* skip-external-locking option, mysqld:  server-options.     (line 1185)
* skip-grant-tables option, mysqld <1>:  privileges-options. (line   99)
* skip-grant-tables option, mysqld:      server-options.     (line 1193)
* skip-host-cache option, mysqld:        server-options.     (line 1209)
* skip-innodb option, mysqld:            server-options.     (line 1215)
* skip-kill-mysqld option, mysqld_safe:  mysqld-safe.        (line  202)
* skip-line-numbers option, mysql:       mysql-command-options.
                                                             (line  431)
* skip-merge option, mysqld:             privileges-options. (line  110)
* skip-name-resolve option, mysqld <1>:  privileges-options. (line  119)
* skip-name-resolve option, mysqld:      server-options.     (line 1221)
* skip-ndbcluster option, mysqld:        mysql-cluster-mysqld-command-options.
                                                             (line   59)
* skip-networking option, mysqld <1>:    privileges-options. (line  124)
* skip-networking option, mysqld:        server-options.     (line 1228)
* skip-opt option, mysqldump:            mysqldump.          (line  762)
* skip-safemalloc option, mysqld:        server-options.     (line 1275)
* skip-show-database option, mysqld <1>: privileges-options. (line  129)
* skip-show-database option, mysqld:     server-options.     (line 1283)
* skip-slave-start option, mysqld:       replication-options.
                                                             (line  586)
* skip-stack-trace option, mysqld:       server-options.     (line 1299)
* skip-symbolic-links option, mysqld:    server-options.     (line 1258)
* skip-syslog option, mysqld_safe:       mysqld-safe.        (line  212)
* skip-thread-priority option, mysqld:   server-options.     (line 1306)
* skip-use-db option, mysql_find_rows:   mysql-find-rows.    (line   39)
* slave option, mysqlslap:               mysqlslap.          (line  358)
* slave-load-tmpdir option, mysqld:      replication-options.
                                                             (line  598)
* slave-net-timeout option, mysqld:      replication-options.
                                                             (line  619)
* slave-skip-errors option, mysqld:      replication-options.
                                                             (line  630)
* slave_allow_batching:                  mysql-cluster-replication-starting.
                                                             (line   91)
* slave_compressed_protocol option, mysqld: replication-options.
                                                             (line  592)
* sleep option, mysqladmin:              mysqladmin.         (line  377)
* SLEEP():                               miscellaneous-functions.
                                                             (line  185)
* Sleep, thread command:                 thread-commands.    (line  120)
* slow queries:                          mysqladmin.         (line  191)
* slow query log:                        slow-query-log.     (line    6)
* slow-query-log option, mysqld:         server-options.     (line 1310)
* SMALLINT data type:                    numeric-type-overview.
                                                             (line  108)
* socket location, changing:             configure-options.  (line  329)
* socket option:                         connecting.         (line  169)
* socket option, mysql:                  mysql-command-options.
                                                             (line  437)
* socket option, mysql_explain_log:      mysql-convert-table-format.
                                                             (line   51)
* socket option, mysql_setpermission:    mysql-setpermission.
                                                             (line   49)
* socket option, mysqladmin:             mysqladmin.         (line  384)
* socket option, mysqlbinlog:            mysqlbinlog.        (line  250)
* socket option, mysqlcheck:             mysqlcheck.         (line  327)
* socket option, mysqld:                 server-options.     (line 1329)
* socket option, mysqld_safe:            mysqld-safe.        (line  207)
* socket option, mysqldump:              mysqldump.          (line  766)
* socket option, mysqlhotcopy:           mysqlhotcopy.       (line  161)
* socket option, mysqlimport:            mysqlimport.        (line  253)
* socket option, mysqlmanager:           instance-manager-command-options.
                                                             (line  210)
* socket option, mysqlshow:              mysqlshow.          (line  180)
* socket option, mysqlslap:              mysqlslap.          (line  365)
* Solaris installation problems:         solaris.            (line   11)
* Solaris troubleshooting:               compilation-problems.
                                                             (line  104)
* Solaris x86_64 issues:                 innodb-tuning.      (line   10)
* Solaris, installation:                 solaris-installation.
                                                             (line    6)
* SOME:                                  any-in-some-subqueries.
                                                             (line    6)
* sort-index option, myisamchk:          myisamchk-other-options.
                                                             (line   40)
* sort-records option, myisamchk:        myisamchk-other-options.
                                                             (line   45)
* sort-recover option, myisamchk:        myisamchk-repair-options.
                                                             (line  107)
* sort_buffer_size myisamchk variable:   myisamchk-general-options.
                                                             (line   45)
* sort_key_blocks myisamchk variable:    myisamchk-general-options.
                                                             (line   45)
* Sorting for group, thread state:       general-thread-states.
                                                             (line  249)
* Sorting for order, thread state:       general-thread-states.
                                                             (line  253)
* Sorting index, thread state:           general-thread-states.
                                                             (line  257)
* Sorting result, thread state:          general-thread-states.
                                                             (line  262)
* sorting, character sets:               charset-configuration.
                                                             (line   10)
* sorting, data:                         sorting-rows.       (line    6)
* sorting, grant tables <1>:             request-access.     (line   49)
* sorting, grant tables:                 connection-access.  (line  195)
* sorting, table rows:                   sorting-rows.       (line    6)
* SOUNDEX():                             string-functions.   (line  567)
* SOUNDS LIKE:                           string-functions.   (line  606)
* source (mysql client command) <1>:     batch-commands.     (line    6)
* source (mysql client command):         batch-mode.         (line   90)
* source command, mysql:                 mysql-commands.     (line  181)
* source distribution, installing:       installing-source.  (line   16)
* source distributions, on Linux:        source-notes-linux. (line    6)
* SPACE():                               string-functions.   (line  610)
* spassword option, mysqlaccess:         mysqlaccess.        (line  129)
* Spatial Extensions in MySQL:           gis-introduction.   (line    6)
* speed, compiling:                      compile-and-link-options.
                                                             (line    6)
* speed, increasing with replication:    replication.        (line   13)
* speed, inserting:                      insert-speed.       (line    6)
* speed, linking:                        compile-and-link-options.
                                                             (line    6)
* speed, of queries <1>:                 select-speed.       (line    6)
* speed, of queries:                     query-speed.        (line   31)
* sporadic-binlog-dump-fail option, mysqld: server-options.  (line 1236)
* SQL mode, ONLY_FULL_GROUP_BY:          group-by-hidden-fields.
                                                             (line    6)
* SQL node (MySQL Cluster), defined:     mysql-cluster-basics.
                                                             (line    6)
* SQL nodes (MySQL Cluster):             mysql-cluster-mysqld-process.
                                                             (line    6)
* SQL statements relating to MySQL Cluster: mysql-cluster-sql-statements.
                                                             (line    6)
* SQL statements, replication masters:   replication-master-sql.
                                                             (line   12)
* SQL statements, replication slaves:    replication-slave-sql.
                                                             (line   17)
* SQL, defined:                          what-is-mysql.      (line   42)
* SQL-92, extensions to:                 compatibility.      (line   15)
* sql-mode option, mysqld:               server-options.     (line 1355)
* SQL_BIG_RESULT:                        select.             (line  440)
* SQL_BUFFER_RESULT:                     select.             (line  446)
* SQL_CACHE <1>:                         select.             (line  461)
* SQL_CACHE:                             query-cache-in-select.
                                                             (line    8)
* SQL_CALC_FOUND_ROWS:                   select.             (line  456)
* SQL_NO_CACHE <1>:                      select.             (line  461)
* SQL_NO_CACHE:                          query-cache-in-select.
                                                             (line    8)
* SQL_SMALL_RESULT:                      select.             (line  451)
* sql_yacc.cc problems:                  compilation-problems.
                                                             (line   38)
* SQRT():                                mathematical-functions.
                                                             (line  500)
* square brackets:                       data-types.         (line   40)
* SRID():                                general-geometry-property-functions.
                                                             (line   51)
* SSH:                                   windows-and-ssh.    (line    6)
* SSL:                                   secure-using-ssl.   (line    6)
* SSL and X509 Basics:                   secure-connections. (line   14)
* SSL command options:                   ssl-options.        (line    6)
* ssl option:                            ssl-options.        (line   31)
* SSL options:                           connecting.         (line  182)
* SSL options, mysql:                    mysql-command-options.
                                                             (line  442)
* SSL options, mysqladmin:               mysqladmin.         (line  389)
* SSL options, mysqlcheck:               mysqlcheck.         (line  332)
* SSL options, mysqld <1>:               privileges-options. (line  139)
* SSL options, mysqld:                   server-options.     (line 1245)
* SSL options, mysqldump:                mysqldump.          (line  771)
* SSL options, mysqlimport:              mysqlimport.        (line  258)
* SSL options, mysqlshow:                mysqlshow.          (line  185)
* SSL options, mysqlslap:                mysqlslap.          (line  370)
* SSL related options:                   grant.              (line  439)
* ssl-ca option:                         ssl-options.        (line   59)
* ssl-capath option:                     ssl-options.        (line   63)
* ssl-cert option:                       ssl-options.        (line   68)
* ssl-cipher option:                     ssl-options.        (line   73)
* ssl-key option:                        ssl-options.        (line   92)
* ssl-verify-server-cert option:         ssl-options.        (line   97)
* standalone option, mysqld:             server-options.     (line 1251)
* standalone option, mysqlmanager:       instance-manager-command-options.
                                                             (line  216)
* Standard SQL, differences from <1>:    grant.              (line  546)
* Standard SQL, differences from:        differences-from-ansi.
                                                             (line   15)
* Standard SQL, extensions to <1>:       extensions-to-ansi. (line    6)
* Standard SQL, extensions to:           compatibility.      (line   15)
* standards compatibility:               compatibility.      (line   15)
* START BACKUP:                          mysql-cluster-backup-using-management-client.
                                                             (line   15)
* START BACKUP, NOWAIT:                  mysql-cluster-backup-using-management-client.
                                                             (line   35)
* START BACKUP, WAIT COMPLETED:          mysql-cluster-backup-using-management-client.
                                                             (line   53)
* START BACKUP, WAIT STARTED:            mysql-cluster-backup-using-management-client.
                                                             (line   44)
* START command (MySQL Cluster):         mysql-cluster-mgm-client-commands.
                                                             (line   34)
* START SLAVE:                           start-slave.        (line    6)
* START TRANSACTION:                     commit.             (line    6)
* START, XA transactions:                xa-statements.      (line    6)
* start-datetime option, mysqlbinlog:    mysqlbinlog.        (line  255)
* start-position option, mysqlbinlog:    mysqlbinlog.        (line  275)
* start_row option, mysql_find_rows:     mysql-find-rows.    (line   43)
* StartFailureTimeout:                   mysql-cluster-ndbd-definition.
                                                             (line  968)
* Starting many servers:                 multiple-servers.   (line   12)
* starting slave, thread state:          slave-connection-thread-states.
                                                             (line   35)
* starting, comments:                    ansi-diff-comments. (line    6)
* starting, mysqld:                      changing-mysql-user.
                                                             (line    6)
* starting, the server:                  unix-post-installation.
                                                             (line   46)
* starting, the server automatically:    automatic-start.    (line    6)
* StartPartialTimeout:                   mysql-cluster-ndbd-definition.
                                                             (line  948)
* StartPartitionedTimeout:               mysql-cluster-ndbd-definition.
                                                             (line  959)
* StartPoint():                          linestring-property-functions.
                                                             (line   64)
* STARTUP Events (MySQL Cluster):        mysql-cluster-log-events.
                                                             (line   54)
* startup options, default:              option-files.       (line   11)
* startup parameters:                    server-parameters.  (line    6)
* startup parameters, mysql:             mysql-command-options.
                                                             (line    6)
* startup parameters, mysqladmin:        mysqladmin.         (line  226)
* startup parameters, tuning:            system-optimization.
                                                             (line    6)
* statefile option, comp_err:            comp-err.           (line   64)
* statements, GRANT:                     adding-users.       (line    6)
* statements, INSERT:                    adding-users.       (line   98)
* statements, replication masters:       replication-master-sql.
                                                             (line   12)
* statements, replication slaves:        replication-slave-sql.
                                                             (line   17)
* statically, compiling:                 configure-options.  (line  341)
* STATISTICS Events (MySQL Cluster):     mysql-cluster-log-events.
                                                             (line  170)
* STATISTICS, INFORMATION_SCHEMA table:  statistics-table.   (line    6)
* Statistics, thread command:            thread-commands.    (line  124)
* statistics, thread state:              general-thread-states.
                                                             (line  267)
* stats option, myisam_ftdump:           myisam-ftdump.      (line   63)
* stats_method myisamchk variable:       myisamchk-general-options.
                                                             (line   45)
* STATUS command (MySQL Cluster):        mysql-cluster-mgm-client-commands.
                                                             (line   78)
* status command, mysql:                 mysql-commands.     (line  187)
* status command, results:               mysqladmin.         (line  176)
* status option, mysqlshow:              mysqlshow.          (line  191)
* status variables <1>:                  show-status.        (line    6)
* status variables:                      server-status-variables.
                                                             (line    6)
* status, tables:                        show-table-status.  (line    6)
* STD():                                 group-by-functions. (line  218)
* STDDEV():                              group-by-functions. (line  226)
* STDDEV_POP():                          group-by-functions. (line  234)
* STDDEV_SAMP():                         group-by-functions. (line  242)
* STOP command (MySQL Cluster):          mysql-cluster-mgm-client-commands.
                                                             (line   47)
* STOP SLAVE:                            stop-slave.         (line    6)
* stop-datetime option, mysqlbinlog:     mysqlbinlog.        (line  268)
* stop-position option, mysqlbinlog:     mysqlbinlog.        (line  281)
* StopOnError:                           mysql-cluster-ndbd-definition.
                                                             (line  818)
* stopping, the server:                  automatic-start.    (line    6)
* stopword list, user-defined:           fulltext-fine-tuning.
                                                             (line   40)
* storage engine, ARCHIVE:               archive-storage-engine.
                                                             (line    6)
* storage engines, choosing:             storage-engines.    (line   21)
* storage of data:                       design.             (line    6)
* storage requirements, data type:       storage-requirements.
                                                             (line    6)
* storage space, minimizing:             data-size.          (line    6)
* stored functions, and INSERT DELAYED:  insert.             (line  220)
* stored procedures:                     stored-procedures.  (line   13)
* stored procedures and triggers, defined: ansi-diff-triggers.
                                                             (line    6)
* stored routine restrictions:           routine-restrictions.
                                                             (line    6)
* stored routines, LAST_INSERT_ID():     stored-procedure-last-insert-id.
                                                             (line    6)
* storing row into queue, thread state:  delayed-insert-thread-states.
                                                             (line   38)
* STR_TO_DATE():                         date-and-time-functions.
                                                             (line  785)
* STRAIGHT_JOIN <1>:                     join.               (line    6)
* STRAIGHT_JOIN <2>:                     select.             (line  423)
* STRAIGHT_JOIN <3>:                     left-join-optimization.
                                                             (line   38)
* STRAIGHT_JOIN:                         using-explain.      (line   32)
* STRCMP():                              string-comparison-functions.
                                                             (line  193)
* STRICT SQL mode:                       server-sql-mode.    (line   81)
* STRICT_ALL_TABLES SQL mode:            server-sql-mode.    (line  366)
* STRICT_TRANS_TABLES SQL mode:          server-sql-mode.    (line   60)
* string collating:                      string-collating.   (line    6)
* string comparison functions:           string-comparison-functions.
                                                             (line    6)
* string comparisons, case sensitivity:  string-comparison-functions.
                                                             (line   15)
* string functions:                      string-functions.   (line   11)
* string literal introducer <1>:         charset-literal.    (line   11)
* string literal introducer:             string-syntax.      (line   27)
* string types:                          string-types.       (line   14)
* StringMemory:                          mysql-cluster-ndbd-definition.
                                                             (line  263)
* strings, defined:                      literals.           (line   15)
* strings, escaping characters:          literals.           (line   15)
* strings, non-delimited:                datetime.           (line  122)
* striping, defined:                     disk-issues.        (line   31)
* SUBDATE():                             date-and-time-functions.
                                                             (line  821)
* subpartitioning:                       partitioning-subpartitions.
                                                             (line    6)
* subpartitions:                         partitioning-subpartitions.
                                                             (line    6)
* subqueries:                            subqueries.         (line   20)
* subqueries, correlated:                correlated-subqueries.
                                                             (line    6)
* subqueries, errors:                    subquery-errors.    (line    6)
* subqueries, rewriting as joins:        rewriting-subqueries.
                                                             (line    6)
* subqueries, with ALL:                  all-subqueries.     (line    6)
* subqueries, with ANY, IN, SOME:        any-in-some-subqueries.
                                                             (line    6)
* subqueries, with EXISTS:               exists-and-not-exists-subqueries.
                                                             (line    6)
* subqueries, with NOT EXISTS:           exists-and-not-exists-subqueries.
                                                             (line    6)
* subqueries, with ROW:                  row-subqueries.     (line    6)
* subquery:                              subqueries.         (line   20)
* subquery optimization:                 in-subquery-optimization.
                                                             (line    6)
* subquery restrictions:                 subquery-restrictions.
                                                             (line    6)
* subselects:                            subqueries.         (line   20)
* SUBSTR():                              string-functions.   (line  617)
* SUBSTRING():                           string-functions.   (line  622)
* SUBSTRING_INDEX():                     string-functions.   (line  655)
* SUBTIME():                             date-and-time-functions.
                                                             (line  839)
* subtraction (-):                       arithmetic-functions.
                                                             (line   50)
* suffix option, mysqlhotcopy:           mysqlhotcopy.       (line  165)
* SUM():                                 group-by-functions. (line  249)
* SUM(DISTINCT):                         group-by-functions. (line  249)
* superuser:                             default-privileges. (line    6)
* superuser option, mysqlaccess:         mysqlaccess.        (line  139)
* support, for operating systems:        which-os.           (line    6)
* suppression, default values:           constraint-invalid-data.
                                                             (line    6)
* Sybase compatibility:                  use.                (line   27)
* symbolic links <1>:                    windows-symbolic-links.
                                                             (line    6)
* symbolic links:                        symbolic-links.     (line   12)
* symbolic-links option, mysqld:         server-options.     (line 1258)
* symbols-file option, resolve_stack_dump: resolve-stack-dump.
                                                             (line   28)
* SymDifference():                       spatial-operators.  (line   32)
* Syncing ndb table schema operation and binlog, thread state: mysql-cluster-thread-states.
                                                             (line   20)
* syntax, regular expression:            regexp.             (line    6)
* SYSDATE():                             date-and-time-functions.
                                                             (line  850)
* sysdate-is-now option, mysqld:         server-options.     (line 1390)
* syslog option, mysqld_safe:            mysqld-safe.        (line  212)
* syslog-tag option, mysqld_safe:        mysqld-safe.        (line  219)
* system command, mysql:                 mysql-commands.     (line  194)
* System lock, thread state:             general-thread-states.
                                                             (line  272)
* system optimization:                   system-optimization.
                                                             (line    6)
* system table, optimizer <1>:           select.             (line  429)
* system table, optimizer:               using-explain.      (line  121)
* system variables <1>:                  show-variables.     (line    6)
* system variables <2>:                  using-system-variables.
                                                             (line   11)
* system variables:                      server-system-variables.
                                                             (line    6)
* system, privilege:                     what-privileges.    (line    6)
* system, security:                      security.           (line   14)
* SYSTEM_USER():                         information-functions.
                                                             (line  473)
* tab (\t) <1>:                          load-data.          (line  416)
* tab (\t):                              string-syntax.      (line   54)
* tab option, mysqldump:                 mysqldump.          (line  777)
* table aliases:                         select.             (line  133)
* table cache:                           table-cache.        (line    6)
* Table Dump, thread command:            thread-commands.    (line  128)
* table is full <1>:                     full-table.         (line    6)
* table is full:                         server-session-variables.
                                                             (line   66)
* Table lock, thread state:              general-thread-states.
                                                             (line  282)
* table names, case sensitivity:         identifier-case-sensitivity.
                                                             (line    6)
* table names, case-sensitivity:         extensions-to-ansi. (line   38)
* table option, mysql:                   mysql-command-options.
                                                             (line  448)
* table option, mysqlaccess:             mysqlaccess.        (line  143)
* table scans, avoiding:                 how-to-avoid-table-scan.
                                                             (line    6)
* table types, choosing:                 storage-engines.    (line   21)
* table, changing <1>:                   alter-table-problems.
                                                             (line    6)
* table, changing:                       alter-table.        (line    6)
* table, deleting:                       drop-table.         (line    6)
* table, row size:                       storage-requirements.
                                                             (line    9)
* table-level locking:                   internal-locking.   (line    6)
* table_open_cache:                      table-cache.        (line    6)
* TABLE_PRIVILEGES, INFORMATION_SCHEMA table: table-privileges-table.
                                                             (line    6)
* tables option, mysqlcheck:             mysqlcheck.         (line  338)
* tables option, mysqldump:              mysqldump.          (line  803)
* tables, BLACKHOLE:                     blackhole-storage-engine.
                                                             (line    6)
* tables, changing column order:         change-column-order.
                                                             (line    6)
* tables, checking:                      myisamchk-check-options.
                                                             (line    6)
* tables, closing:                       table-cache.        (line    6)
* tables, compressed format:             compressed-format.  (line    6)
* tables, const:                         using-explain.      (line  126)
* tables, constant:                      where-optimizations.
                                                             (line   50)
* tables, copying:                       create-table.       (line 1134)
* tables, counting rows:                 counting-rows.      (line    6)
* tables, creating:                      creating-tables.    (line    6)
* tables, CSV:                           csv-storage-engine. (line   11)
* tables, defragment:                    dynamic-format.     (line   15)
* tables, defragmenting <1>:             optimize-table.     (line    6)
* tables, defragmenting:                 maintenance-schedule.
                                                             (line   40)
* tables, deleting rows:                 deleting-from-related-tables.
                                                             (line    6)
* tables, displaying status:             show-table-status.  (line    6)
* tables, dynamic:                       dynamic-format.     (line    6)
* tables, error checking:                check.              (line    6)
* tables, EXAMPLE:                       example-storage-engine.
                                                             (line    6)
* tables, FEDERATED:                     federated-storage-engine.
                                                             (line   13)
* tables, flush:                         mysqladmin.         (line  200)
* tables, fragmentation:                 optimize-table.     (line    6)
* tables, grant:                         request-access.     (line  166)
* tables, HEAP:                          memory-storage-engine.
                                                             (line    6)
* tables, host:                          request-access.     (line  146)
* tables, improving performance:         data-size.          (line    6)
* tables, information:                   table-info.         (line    6)
* tables, information about:             getting-information.
                                                             (line    6)
* TABLES, INFORMATION_SCHEMA table:      tables-table.       (line    6)
* tables, InnoDB:                        innodb.             (line   26)
* tables, loading data:                  loading-tables.     (line    6)
* tables, maintenance schedule:          maintenance-schedule.
                                                             (line    6)
* tables, maximum size:                  full-table.         (line    6)
* tables, MEMORY:                        memory-storage-engine.
                                                             (line    6)
* tables, MERGE:                         merge-storage-engine.
                                                             (line   10)
* tables, merging:                       merge-storage-engine.
                                                             (line   10)
* tables, multiple:                      multiple-tables.    (line    6)
* tables, MyISAM:                        myisam-storage-engine.
                                                             (line   13)
* tables, names:                         identifiers.        (line   13)
* tables, open:                          table-cache.        (line    6)
* tables, opening:                       table-cache.        (line    6)
* tables, optimizing:                    table-optimization. (line    6)
* tables, partitioning:                  merge-storage-engine.
                                                             (line   10)
* tables, repairing:                     repair.             (line    6)
* tables, retrieving data:               retrieving-data.    (line   18)
* tables, selecting columns:             selecting-columns.  (line    6)
* tables, selecting rows:                selecting-rows.     (line    6)
* tables, sorting rows:                  sorting-rows.       (line    6)
* tables, symbolic links:                symbolic-links-to-tables.
                                                             (line    6)
* tables, system:                        using-explain.      (line  121)
* tables, too many:                      creating-many-tables.
                                                             (line    6)
* tables, unique ID for last row:        getting-unique-id.  (line    6)
* tables, updating:                      ansi-diff-transactions.
                                                             (line    6)
* TAN():                                 mathematical-functions.
                                                             (line  511)
* tar, problems on Solaris <1>:          solaris.            (line   11)
* tar, problems on Solaris:              solaris-installation.
                                                             (line    6)
* tc-heuristic-recover option, mysqld:   server-options.     (line 1407)
* Tcl API:                               tcl.                (line    6)
* tcp-ip option, mysqld_multi:           mysqld-multi.       (line  140)
* TCP/IP <1>:                            windows-testing.    (line    6)
* TCP/IP:                                windows-select-server.
                                                             (line   33)
* tee command, mysql:                    mysql-commands.     (line  200)
* tee option, mysql:                     mysql-command-options.
                                                             (line  454)
* temp-pool option, mysqld:              server-options.     (line 1417)
* temporary file, write access:          mysql-install-db-problems.
                                                             (line   64)
* temporary tables, internal:            internal-temporary-tables.
                                                             (line    6)
* temporary tables, problems:            temporary-table-problems.
                                                             (line    6)
* terminal monitor, defined:             tutorial.           (line   17)
* test option, myisampack:               myisampack.         (line   93)
* testing mysqld, mysqltest:             mysql-test-suite.   (line    6)
* testing, connection to the server:     connection-access.  (line    6)
* testing, installation:                 unix-post-installation.
                                                             (line   46)
* testing, of MySQL releases:            choosing-version.   (line  122)
* testing, post-installation:            post-installation.  (line   12)
* TEXT columns, default values:          blob.               (line   49)
* TEXT columns, indexing <1>:            create-table.       (line  427)
* TEXT columns, indexing:                indexes.            (line   15)
* TEXT data type <1>:                    blob.               (line    6)
* TEXT data type:                        string-type-overview.
                                                             (line  175)
* text files, importing:                 batch-commands.     (line    6)
* TEXT, size:                            storage-requirements.
                                                             (line  140)
* thread cache:                          connection-threads. (line    6)
* thread command, Binlog Dump:           thread-commands.    (line    8)
* thread command, Change user:           thread-commands.    (line   13)
* thread command, Close stmt:            thread-commands.    (line   17)
* thread command, Connect:               thread-commands.    (line   21)
* thread command, Connect Out:           thread-commands.    (line   25)
* thread command, Create DB:             thread-commands.    (line   29)
* thread command, Daemon:                thread-commands.    (line   33)
* thread command, Debug:                 thread-commands.    (line   38)
* thread command, Delayed insert:        thread-commands.    (line   42)
* thread command, Drop DB:               thread-commands.    (line   46)
* thread command, Error:                 thread-commands.    (line   50)
* thread command, Execute:               thread-commands.    (line   52)
* thread command, Fetch:                 thread-commands.    (line   56)
* thread command, Field List:            thread-commands.    (line   61)
* thread command, Init DB:               thread-commands.    (line   65)
* thread command, Kill:                  thread-commands.    (line   69)
* thread command, Long Data:             thread-commands.    (line   73)
* thread command, Ping:                  thread-commands.    (line   78)
* thread command, Prepare:               thread-commands.    (line   82)
* thread command, Processlist:           thread-commands.    (line   86)
* thread command, Query:                 thread-commands.    (line   90)
* thread command, Quit:                  thread-commands.    (line   94)
* thread command, Refresh:               thread-commands.    (line   98)
* thread command, Register Slave:        thread-commands.    (line  103)
* thread command, Reset stmt:            thread-commands.    (line  107)
* thread command, Set option:            thread-commands.    (line  111)
* thread command, Shutdown:              thread-commands.    (line  116)
* thread command, Sleep:                 thread-commands.    (line  120)
* thread command, Statistics:            thread-commands.    (line  124)
* thread command, Table Dump:            thread-commands.    (line  128)
* thread command, Time:                  thread-commands.    (line  132)
* thread commands:                       thread-commands.    (line    6)
* thread packages, differences between:  thread-packages.    (line    6)
* thread state, After create:            general-thread-states.
                                                             (line   11)
* thread state, allocating local table:  delayed-insert-thread-states.
                                                             (line   16)
* thread state, Analyzing:               general-thread-states.
                                                             (line   18)
* thread state, Changing master:         slave-connection-thread-states.
                                                             (line    9)
* thread state, Checking master version: slave-io-thread-states.
                                                             (line   19)
* thread state, Checking table:          general-thread-states.
                                                             (line   23)
* thread state, cleaning up:             general-thread-states.
                                                             (line   27)
* thread state, Clearing:                event-scheduler-thread-states.
                                                             (line   10)
* thread state, closing tables:          general-thread-states.
                                                             (line   32)
* thread state, Committing events to binlog: mysql-cluster-thread-states.
                                                             (line    6)
* thread state, Connecting to master:    slave-io-thread-states.
                                                             (line   15)
* thread state, converting HEAP to MyISAM: general-thread-states.
                                                             (line   39)
* thread state, copy to tmp table:       general-thread-states.
                                                             (line   44)
* thread state, Copying to group table:  general-thread-states.
                                                             (line   50)
* thread state, Copying to tmp table:    general-thread-states.
                                                             (line   55)
* thread state, Copying to tmp table on disk: general-thread-states.
                                                             (line   59)
* thread state, Creating delayed handler: delayed-insert-thread-states.
                                                             (line   21)
* thread state, Creating index:          general-thread-states.
                                                             (line   66)
* thread state, Creating sort index:     general-thread-states.
                                                             (line   71)
* thread state, creating table:          general-thread-states.
                                                             (line   76)
* thread state, Creating table from master dump: slave-connection-thread-states.
                                                             (line   13)
* thread state, Creating tmp table:      general-thread-states.
                                                             (line   81)
* thread state, deleting from main table: general-thread-states.
                                                             (line   88)
* thread state, deleting from reference tables: general-thread-states.
                                                             (line   94)
* thread state, discard_or_import_tablespace: general-thread-states.
                                                             (line   99)
* thread state, end:                     general-thread-states.
                                                             (line  104)
* thread state, Execution of init_command: general-thread-states.
                                                             (line  110)
* thread state, Finished reading one binlog; switching to next binlog: master-thread-states.
                                                             (line   17)
* thread state, Flushing tables:         general-thread-states.
                                                             (line  120)
* thread state, freeing items:           general-thread-states.
                                                             (line  115)
* thread state, FULLTEXT initialization: general-thread-states.
                                                             (line  125)
* thread state, got handler lock:        delayed-insert-thread-states.
                                                             (line   25)
* thread state, got old table:           delayed-insert-thread-states.
                                                             (line   31)
* thread state, Has read all relay log; waiting for the slave I/O thread to update it: slave-sql-thread-states.
                                                             (line   18)
* thread state, Has sent all binlog to slave; waiting for binlog to be updated: master-thread-states.
                                                             (line   22)
* thread state, init:                    general-thread-states.
                                                             (line  130)
* thread state, Initialized:             event-scheduler-thread-states.
                                                             (line   15)
* thread state, insert:                  delayed-insert-thread-states.
                                                             (line   73)
* thread state, Killed:                  general-thread-states.
                                                             (line  135)
* thread state, Killing slave:           slave-connection-thread-states.
                                                             (line   19)
* thread state, Locked:                  general-thread-states.
                                                             (line  144)
* thread state, logging slow query:      general-thread-states.
                                                             (line  148)
* thread state, login:                   general-thread-states.
                                                             (line  152)
* thread state, Making temp file:        slave-sql-thread-states.
                                                             (line   25)
* thread state, Opening master dump table: slave-connection-thread-states.
                                                             (line   23)
* thread state, Opening mysql.ndb_apply_status: mysql-cluster-thread-states.
                                                             (line    8)
* thread state, Opening table:           general-thread-states.
                                                             (line  157)
* thread state, Opening tables:          general-thread-states.
                                                             (line  157)
* thread state, preparing:               general-thread-states.
                                                             (line  164)
* thread state, Processing events:       mysql-cluster-thread-states.
                                                             (line   10)
* thread state, Processing events from schema table: mysql-cluster-thread-states.
                                                             (line   14)
* thread state, Purging old relay logs:  general-thread-states.
                                                             (line  168)
* thread state, query end:               general-thread-states.
                                                             (line  172)
* thread state, Queueing master event to the relay log: slave-io-thread-states.
                                                             (line   56)
* thread state, Reading event from the relay log: slave-sql-thread-states.
                                                             (line   13)
* thread state, Reading from net:        general-thread-states.
                                                             (line  177)
* thread state, Reading master dump table data: slave-connection-thread-states.
                                                             (line   27)
* thread state, Rebuilding the index on master dump table: slave-connection-thread-states.
                                                             (line   31)
* thread state, Reconnecting after a failed binlog dump request: slave-io-thread-states.
                                                             (line   44)
* thread state, Reconnecting after a failed master event read: slave-io-thread-states.
                                                             (line   68)
* thread state, Registering slave on master: slave-io-thread-states.
                                                             (line   24)
* thread state, Removing duplicates:     general-thread-states.
                                                             (line  181)
* thread state, removing tmp table:      general-thread-states.
                                                             (line  188)
* thread state, rename:                  general-thread-states.
                                                             (line  194)
* thread state, rename result table:     general-thread-states.
                                                             (line  198)
* thread state, Reopen tables:           general-thread-states.
                                                             (line  203)
* thread state, Repair by sorting:       general-thread-states.
                                                             (line  209)
* thread state, Repair done:             general-thread-states.
                                                             (line  213)
* thread state, Repair with keycache:    general-thread-states.
                                                             (line  218)
* thread state, Requesting binlog dump:  slave-io-thread-states.
                                                             (line   29)
* thread state, reschedule:              delayed-insert-thread-states.
                                                             (line   77)
* thread state, Rolling back:            general-thread-states.
                                                             (line  223)
* thread state, Saving state:            general-thread-states.
                                                             (line  227)
* thread state, Searching rows for update: general-thread-states.
                                                             (line  234)
* thread state, Sending binlog event to slave: master-thread-states.
                                                             (line   11)
* thread state, setup:                   general-thread-states.
                                                             (line  245)
* thread state, Shutting down:           mysql-cluster-thread-states.
                                                             (line   18)
* thread state, Sorting for group:       general-thread-states.
                                                             (line  249)
* thread state, Sorting for order:       general-thread-states.
                                                             (line  253)
* thread state, Sorting index:           general-thread-states.
                                                             (line  257)
* thread state, Sorting result:          general-thread-states.
                                                             (line  262)
* thread state, starting slave:          slave-connection-thread-states.
                                                             (line   35)
* thread state, statistics:              general-thread-states.
                                                             (line  267)
* thread state, storing row into queue:  delayed-insert-thread-states.
                                                             (line   38)
* thread state, Syncing ndb table schema operation and binlog: mysql-cluster-thread-states.
                                                             (line   20)
* thread state, System lock:             general-thread-states.
                                                             (line  272)
* thread state, Table lock:              general-thread-states.
                                                             (line  282)
* thread state, update:                  delayed-insert-thread-states.
                                                             (line   43)
* thread state, Updating:                general-thread-states.
                                                             (line  287)
* thread state, updating main table:     general-thread-states.
                                                             (line  291)
* thread state, updating reference tables: general-thread-states.
                                                             (line  297)
* thread state, upgrading lock:          delayed-insert-thread-states.
                                                             (line   82)
* thread state, User lock:               general-thread-states.
                                                             (line  302)
* thread state, waiting for delay_list:  delayed-insert-thread-states.
                                                             (line   45)
* thread state, Waiting for event from ndbcluster: mysql-cluster-thread-states.
                                                             (line   25)
* thread state, Waiting for first event from ndbcluster: mysql-cluster-thread-states.
                                                             (line   30)
* thread state, waiting for handler insert: delayed-insert-thread-states.
                                                             (line   52)
* thread state, waiting for handler lock: delayed-insert-thread-states.
                                                             (line   57)
* thread state, waiting for handler open: delayed-insert-thread-states.
                                                             (line   63)
* thread state, Waiting for INSERT:      delayed-insert-thread-states.
                                                             (line   87)
* thread state, Waiting for master to send event: slave-io-thread-states.
                                                             (line   48)
* thread state, Waiting for master update: slave-io-thread-states.
                                                             (line   11)
* thread state, Waiting for ndbcluster binlog update to reach current position: mysql-cluster-thread-states.
                                                             (line   32)
* thread state, Waiting for ndbcluster to start: mysql-cluster-thread-states.
                                                             (line   34)
* thread state, Waiting for next activation: event-scheduler-thread-states.
                                                             (line   20)
* thread state, Waiting for scheduler to stop: event-scheduler-thread-states.
                                                             (line   25)
* thread state, Waiting for schema epoch: mysql-cluster-thread-states.
                                                             (line   36)
* thread state, Waiting for slave mutex on exit <1>: slave-sql-thread-states.
                                                             (line   31)
* thread state, Waiting for slave mutex on exit: slave-io-thread-states.
                                                             (line   82)
* thread state, Waiting for table:       general-thread-states.
                                                             (line  307)
* thread state, Waiting for tables:      general-thread-states.
                                                             (line  307)
* thread state, Waiting for the next event in relay log: slave-sql-thread-states.
                                                             (line    9)
* thread state, Waiting for the slave SQL thread to free enough relay log space: slave-io-thread-states.
                                                             (line   74)
* thread state, Waiting on cond:         general-thread-states.
                                                             (line  319)
* thread state, Waiting on empty queue:  event-scheduler-thread-states.
                                                             (line   30)
* thread state, Waiting to finalize termination: master-thread-states.
                                                             (line   29)
* thread state, Waiting to reconnect after a failed binlog dump request: slave-io-thread-states.
                                                             (line   36)
* thread state, Waiting to reconnect after a failed master event read: slave-io-thread-states.
                                                             (line   61)
* thread state, Writing to net:          general-thread-states.
                                                             (line  324)
* thread states, delayed inserts:        delayed-insert-thread-states.
                                                             (line    6)
* thread states, event scheduler:        event-scheduler-thread-states.
                                                             (line    6)
* thread states, general:                general-thread-states.
                                                             (line    6)
* thread states, MySQL Cluster:          mysql-cluster-thread-states.
                                                             (line    6)
* thread states, replication master:     master-thread-states.
                                                             (line    6)
* thread states, replication slave <1>:  slave-connection-thread-states.
                                                             (line    6)
* thread states, replication slave <2>:  slave-sql-thread-states.
                                                             (line    6)
* thread states, replication slave:      slave-io-thread-states.
                                                             (line    6)
* thread support:                        which-os.           (line    6)
* thread support, non-native:            mit-pthreads.       (line    6)
* threaded clients:                      threaded-clients.   (line    6)
* threads <1>:                           mysql-internals.    (line   11)
* threads <2>:                           show-processlist.   (line    6)
* threads:                               mysqladmin.         (line  182)
* threads, display:                      show-processlist.   (line    6)
* threads, RTS:                          rts-threads.        (line    6)
* TIME data type <1>:                    time.               (line    6)
* TIME data type:                        date-and-time-type-overview.
                                                             (line   58)
* time types:                            storage-requirements.
                                                             (line   72)
* time zone problems:                    timezone-problems.  (line    6)
* TIME():                                date-and-time-functions.
                                                             (line  891)
* Time, thread command:                  thread-commands.    (line  132)
* TIME_FORMAT():                         date-and-time-functions.
                                                             (line  960)
* TIME_TO_SEC():                         date-and-time-functions.
                                                             (line  974)
* TimeBetweenEpochs:                     mysql-cluster-ndbd-definition.
                                                             (line 1058)
* TimeBetweenEpochsTimeout:              mysql-cluster-ndbd-definition.
                                                             (line 1069)
* TimeBetweenGlobalCheckpoints:          mysql-cluster-ndbd-definition.
                                                             (line 1035)
* TimeBetweenInactiveTransactionAbortCheck: mysql-cluster-ndbd-definition.
                                                             (line 1100)
* TimeBetweenLocalCheckpoints:           mysql-cluster-ndbd-definition.
                                                             (line 1014)
* TimeBetweenWatchDogCheck:              mysql-cluster-ndbd-definition.
                                                             (line  922)
* TimeBetweenWatchDogCheckInitial:       mysql-cluster-ndbd-definition.
                                                             (line  937)
* TIMEDIFF():                            date-and-time-functions.
                                                             (line  901)
* timeout <1>:                           insert-delayed.     (line  105)
* timeout <2>:                           miscellaneous-functions.
                                                             (line   40)
* timeout:                               server-system-variables.
                                                             (line 1103)
* timeout option, ndb_waiter:            mysql-cluster-utilities-ndb-waiter.
                                                             (line   54)
* timeout, connect_timeout variable <1>: mysqladmin.         (line  421)
* timeout, connect_timeout variable:     mysql-command-options.
                                                             (line  541)
* timeout, shutdown_timeout variable:    mysqladmin.         (line  426)
* TIMESTAMP data type <1>:               datetime.           (line   10)
* TIMESTAMP data type:                   date-and-time-type-overview.
                                                             (line   28)
* TIMESTAMP():                           date-and-time-functions.
                                                             (line  914)
* TIMESTAMP, and NULL values:            problems-with-null. (line   71)
* TIMESTAMPADD():                        date-and-time-functions.
                                                             (line  926)
* TIMESTAMPDIFF():                       date-and-time-functions.
                                                             (line  947)
* timezone option, mysqld_safe:          mysqld-safe.        (line  227)
* TINYBLOB data type:                    string-type-overview.
                                                             (line  151)
* TINYINT data type:                     numeric-type-overview.
                                                             (line   40)
* TINYTEXT data type:                    string-type-overview.
                                                             (line  157)
* tips, optimization:                    miscellaneous-optimization-tips.
                                                             (line    6)
* TMPDIR environment variable <1>:       environment-variables.
                                                             (line   18)
* TMPDIR environment variable:           mysql-install-db-problems.
                                                             (line   76)
* tmpdir option, myisamchk:              myisamchk-repair-options.
                                                             (line  112)
* tmpdir option, myisampack:             myisampack.         (line   97)
* tmpdir option, mysql_upgrade:          mysql-upgrade.      (line   98)
* tmpdir option, mysqld:                 server-options.     (line 1445)
* tmpdir option, mysqlhotcopy:           mysqlhotcopy.       (line  169)
* to-last-log option, mysqlbinlog:       mysqlbinlog.        (line  287)
* TO_DAYS():                             date-and-time-functions.
                                                             (line  983)
* TODO, symlinks:                        symbolic-links-to-tables.
                                                             (line   63)
* tools, list of:                        tools-used-to-create-mysql.
                                                             (line    6)
* Touches():                             functions-that-test-spatial-relationships-between-geometries.
                                                             (line   76)
* trace DBI method:                      using-gdb-on-mysqld.
                                                             (line   86)
* trace files (MySQL Cluster):           mysql-cluster-ndbd-process.
                                                             (line   55)
* TRADITIONAL SQL mode:                  server-sql-mode.    (line   68)
* transaction-isolation option, mysqld:  server-options.     (line 1431)
* transaction-safe tables <1>:           innodb-overview.    (line    6)
* transaction-safe tables:               ansi-diff-transactions.
                                                             (line    6)
* transactional option, ndb_delete_all:  mysql-cluster-utilities-ndb-delete-all.
                                                             (line   19)
* TransactionBufferMemory:               mysql-cluster-ndbd-definition.
                                                             (line  510)
* TransactionDeadlockDetectionTimeout (MySQL Cluster configuration parameter): mysql-cluster-ndbd-definition.
                                                             (line 1120)
* TransactionInactiveTimeout (MySQL Cluster configuration parameter): mysql-cluster-ndbd-definition.
                                                             (line 1109)
* transactions, support <1>:             innodb-overview.    (line    6)
* transactions, support:                 ansi-diff-transactions.
                                                             (line    6)
* Translators, list of:                  documenters-translators.
                                                             (line    6)
* trigger restrictions:                  routine-restrictions.
                                                             (line    6)
* trigger, creating:                     create-trigger.     (line    6)
* trigger, dropping:                     drop-trigger.       (line    6)
* triggers <1>:                          triggers.           (line   12)
* triggers <2>:                          show-triggers.      (line    6)
* triggers:                              ansi-diff-triggers. (line    6)
* triggers option, mysqldump:            mysqldump.          (line  808)
* triggers, and INSERT DELAYED:          insert.             (line  220)
* TRIGGERS, INFORMATION_SCHEMA table:    triggers-table.     (line    6)
* triggers, LAST_INSERT_ID():            stored-procedure-last-insert-id.
                                                             (line    6)
* TRIM():                                string-functions.   (line  671)
* troubleshooting, FreeBSD:              compilation-problems.
                                                             (line  104)
* troubleshooting, Solaris:              compilation-problems.
                                                             (line  104)
* TRUE <1>:                              boolean-values.     (line    6)
* TRUE:                                  number-syntax.      (line    6)
* TRUE, testing for:                     comparison-operators.
                                                             (line  121)
* TRUNCATE:                              truncate.           (line    6)
* TRUNCATE():                            mathematical-functions.
                                                             (line  520)
* TRUNCATE, and MySQL Cluster:           mysql-cluster-limitations-limits.
                                                             (line    9)
* tupscan option, ndb_select_all:        mysql-cluster-utilities-ndb-select-all.
                                                             (line   72)
* tutorial:                              tutorial.           (line   17)
* Twin Studies, queries:                 twin.               (line   11)
* type conversions <1>:                  comparison-operators.
                                                             (line   36)
* type conversions:                      type-conversion.    (line    6)
* type option, ndb_config:               mysql-cluster-utilities-ndb-config.
                                                             (line   86)
* type option, ndb_show_tables:          mysql-cluster-utilities-ndb-show-tables.
                                                             (line   28)
* types, column:                         data-types.         (line   29)
* types, columns:                        choosing-types.     (line    6)
* types, data:                           data-types.         (line   29)
* types, date:                           storage-requirements.
                                                             (line   72)
* types, Date and Time:                  date-and-time-types.
                                                             (line   13)
* types, numeric:                        storage-requirements.
                                                             (line   38)
* types, of tables:                      storage-engines.    (line   21)
* types, portability:                    other-vendor-data-types.
                                                             (line    6)
* types, strings:                        string-types.       (line   14)
* types, time:                           storage-requirements.
                                                             (line   72)
* typographical conventions:             manual-conventions. (line    8)
* TZ environment variable <1>:           timezone-problems.  (line    6)
* TZ environment variable:               environment-variables.
                                                             (line   18)
* tz-utc option, mysqldump:              mysqldump.          (line  813)
* UCASE():                               string-functions.   (line  690)
* UCS-2:                                 charset.            (line   20)
* UDFs <1>:                              drop-function-udf.  (line    6)
* UDFs:                                  create-function-udf.
                                                             (line    6)
* UDFs, compiling:                       udf-compiling.      (line    6)
* UDFs, defined:                         adding-functions.   (line   12)
* UDFs, return values:                   udf-return-values.  (line    6)
* ulimit:                                not-enough-file-handles.
                                                             (line   30)
* UMASK environment variable <1>:        file-permissions.   (line    6)
* UMASK environment variable:            environment-variables.
                                                             (line   18)
* UMASK_DIR environment variable <1>:    file-permissions.   (line   19)
* UMASK_DIR environment variable:        environment-variables.
                                                             (line   18)
* unary minus (-):                       arithmetic-functions.
                                                             (line   57)
* unbuffered option, mysql:              mysql-command-options.
                                                             (line  460)
* UNCOMPRESS():                          encryption-functions.
                                                             (line  290)
* UNCOMPRESSED_LENGTH():                 encryption-functions.
                                                             (line  303)
* UndoDataBuffer:                        mysql-cluster-ndbd-definition.
                                                             (line 1322)
* UndoIndexBuffer:                       mysql-cluster-ndbd-definition.
                                                             (line 1287)
* UNHEX():                               string-functions.   (line  694)
* Unicode:                               charset.            (line   20)
* Unicode Collation Algorithm:           charset-unicode-sets.
                                                             (line   69)
* UNINSTALL PLUGIN:                      uninstall-plugin.   (line    6)
* uninstalling plugins:                  uninstall-plugin.   (line    6)
* UNION <1>:                             union.              (line    6)
* UNION:                                 searching-on-two-keys.
                                                             (line    6)
* Union():                               spatial-operators.  (line   37)
* UNIQUE:                                alter-table.        (line  417)
* unique ID:                             getting-unique-id.  (line    6)
* unique key, constraint:                constraint-primary-key.
                                                             (line    6)
* unique keys, and partitioning keys:    partitioning-limitations-partitioning-keys-unique-keys.
                                                             (line    6)
* unique_subquery join type, optimizer:  using-explain.      (line  212)
* Unix <1>:                              connector-net.      (line   15)
* Unix:                                  myodbc-connector.   (line   17)
* UNIX_TIMESTAMP():                      date-and-time-functions.
                                                             (line 1008)
* UNKNOWN, testing for:                  comparison-operators.
                                                             (line  121)
* unloading, tables:                     retrieving-data.    (line   18)
* UNLOCK TABLES:                         lock-tables.        (line    6)
* unnamed views:                         unnamed-views.      (line    6)
* unpack option, myisamchk:              myisamchk-repair-options.
                                                             (line  122)
* unqualified option, ndb_show_tables:   mysql-cluster-utilities-ndb-show-tables.
                                                             (line   42)
* UNTIL:                                 repeat-statement.   (line    6)
* UPDATE:                                update.             (line    6)
* update, thread state:                  delayed-insert-thread-states.
                                                             (line   43)
* update-state option, myisamchk:        myisamchk-check-options.
                                                             (line   56)
* UpdateXML():                           xml-functions.      (line  275)
* updating main table, thread state:     general-thread-states.
                                                             (line  291)
* updating reference tables, thread state: general-thread-states.
                                                             (line  297)
* updating, releases of MySQL:           many-versions.      (line    6)
* updating, tables:                      ansi-diff-transactions.
                                                             (line    6)
* Updating, thread state:                general-thread-states.
                                                             (line  287)
* upgrades and downgrades (MySQL Cluster), compatibility between versions: mysql-cluster-upgrade-downgrade-compatibility.
                                                             (line    6)
* upgrades, MySQL Cluster <1>:           mysql-cluster-upgrade-downgrade-compatibility.
                                                             (line    6)
* upgrades, MySQL Cluster <2>:           mysql-cluster-rolling-restart.
                                                             (line    6)
* upgrades, MySQL Cluster:               mysql-cluster-upgrade-downgrade.
                                                             (line   11)
* upgrading:                             upgrade.            (line   11)
* upgrading lock, thread state:          delayed-insert-thread-states.
                                                             (line   82)
* upgrading, different architecture:     upgrading-to-arch.  (line    6)
* upgrading, to &current-series;:        upgrading-from-5-0. (line    6)
* UPPER():                               string-functions.   (line  733)
* uptime:                                mysqladmin.         (line  178)
* URLs for downloading MySQL:            getting-mysql.      (line    6)
* usage option, ndb_config:              mysql-cluster-utilities-ndb-config.
                                                             (line   20)
* USE:                                   use.                (line    6)
* use command, mysql:                    mysql-commands.     (line  213)
* USE INDEX:                             index-hints.        (line    6)
* USE KEY:                               index-hints.        (line    6)
* use-frm option, mysqlcheck:            mysqlcheck.         (line  343)
* use-manager option, mysql.server:      mysql-server.       (line   60)
* use-mysqld_safe option, mysql.server:  mysql-server.       (line   56)
* use-threads option, mysqlimport:       mysqlimport.        (line  268)
* use-threads option, mysqlslap:         mysqlslap.          (line  376)
* useHexFormat option, ndb_select_all:   mysql-cluster-utilities-ndb-select-all.
                                                             (line   42)
* user accounts, creating:               create-user.        (line    6)
* user accounts, renaming:               rename-user.        (line    6)
* USER environment variable <1>:         connecting.         (line  209)
* USER environment variable:             environment-variables.
                                                             (line   18)
* User lock, thread state:               general-thread-states.
                                                             (line  302)
* user option:                           connecting.         (line  188)
* user option, mysql:                    mysql-command-options.
                                                             (line  464)
* user option, mysql.server:             mysql-server.       (line   64)
* user option, mysql_explain_log:        mysql-convert-table-format.
                                                             (line   66)
* user option, mysql_setpermission:      mysql-setpermission.
                                                             (line   53)
* user option, mysql_upgrade:            mysql-upgrade.      (line  103)
* user option, mysqlaccess:              mysqlaccess.        (line  147)
* user option, mysqladmin:               mysqladmin.         (line  395)
* user option, mysqlbinlog:              mysqlbinlog.        (line  295)
* user option, mysqlcheck:               mysqlcheck.         (line  349)
* user option, mysqld:                   server-options.     (line 1471)
* user option, mysqld_multi:             mysqld-multi.       (line  148)
* user option, mysqld_safe:              mysqld-safe.        (line  233)
* user option, mysqldump:                mysqldump.          (line  825)
* user option, mysqlhotcopy:             mysqlhotcopy.       (line  173)
* user option, mysqlimport:              mysqlimport.        (line  264)
* user option, mysqlmanager:             instance-manager-command-options.
                                                             (line  222)
* user option, mysqlshow:                mysqlshow.          (line  195)
* user option, mysqlslap:                mysqlslap.          (line  383)
* user privileges, adding:               adding-users.       (line    6)
* user privileges, deleting <1>:         drop-user.          (line    6)
* user privileges, deleting:             removing-users.     (line    6)
* user privileges, dropping <1>:         drop-user.          (line    6)
* user privileges, dropping:             removing-users.     (line    6)
* user table, sorting:                   connection-access.  (line  195)
* user variables:                        user-variables.     (line    6)
* USER():                                information-functions.
                                                             (line  477)
* User-defined functions <1>:            drop-function-udf.  (line    6)
* User-defined functions:                create-function-udf.
                                                             (line    6)
* user-defined functions, adding <1>:    adding-udf.         (line   15)
* user-defined functions, adding:        adding-functions.   (line   12)
* USER_PRIVILEGES, INFORMATION_SCHEMA table: user-privileges-table.
                                                             (line    6)
* username option, mysqlmanager:         instance-manager-command-options.
                                                             (line  233)
* usernames, and passwords:              user-names.         (line    6)
* users, adding <1>:                     quick-install.      (line  166)
* users, adding:                         installing-binary.  (line  167)
* users, deleting <1>:                   drop-user.          (line    6)
* users, deleting:                       removing-users.     (line    6)
* users, root:                           default-privileges. (line    6)
* uses, of MySQL:                        internal-use.       (line    6)
* using multiple disks to start data:    windows-symbolic-links.
                                                             (line    6)
* UTC_DATE():                            date-and-time-functions.
                                                             (line 1062)
* UTC_TIME():                            date-and-time-functions.
                                                             (line 1071)
* UTC_TIMESTAMP():                       date-and-time-functions.
                                                             (line 1080)
* UTF-8:                                 charset.            (line   20)
* utilities, program-development:        programs-overview.  (line  246)
* utility programs:                      programs-overview.  (line  160)
* UUID():                                miscellaneous-functions.
                                                             (line  191)
* UUID_SHORT():                          miscellaneous-functions.
                                                             (line  249)
* valid numbers, examples:               number-syntax.      (line    6)
* VALUES():                              miscellaneous-functions.
                                                             (line  283)
* VAR_POP():                             group-by-functions. (line  257)
* VAR_SAMP():                            group-by-functions. (line  266)
* VARBINARY data type <1>:               binary-varbinary.   (line    6)
* VARBINARY data type:                   string-type-overview.
                                                             (line  145)
* VARCHAR data type <1>:                 string-types.       (line   14)
* VARCHAR data type:                     string-type-overview.
                                                             (line  110)
* VARCHAR, size:                         storage-requirements.
                                                             (line  140)
* VARCHARACTER data type:                string-type-overview.
                                                             (line  110)
* variables, environment:                programs-overview.  (line  300)
* variables, mysqld:                     server-parameters.  (line   11)
* variables, server <1>:                 show-variables.     (line    6)
* variables, server:                     server-system-variables.
                                                             (line    6)
* variables, status <1>:                 show-status.        (line    6)
* variables, status:                     server-status-variables.
                                                             (line    6)
* variables, system <1>:                 show-variables.     (line    6)
* variables, system <2>:                 using-system-variables.
                                                             (line   11)
* variables, system:                     server-system-variables.
                                                             (line    6)
* variables, user:                       user-variables.     (line    6)
* VARIANCE():                            group-by-functions. (line  273)
* verbose option, my_print_defaults:     my-print-defaults.  (line   55)
* verbose option, myisam_ftdump:         myisam-ftdump.      (line   68)
* verbose option, myisamchk:             myisamchk-general-options.
                                                             (line   25)
* verbose option, myisampack:            myisampack.         (line  102)
* verbose option, mysql:                 mysql-command-options.
                                                             (line  468)
* verbose option, mysql_upgrade:         mysql-upgrade.      (line  108)
* verbose option, mysql_waitpid:         mysql-waitpid.      (line   30)
* verbose option, mysqladmin:            mysqladmin.         (line  399)
* verbose option, mysqlcheck:            mysqlcheck.         (line  353)
* verbose option, mysqld_multi:          mysqld-multi.       (line  153)
* verbose option, mysqldump:             mysqldump.          (line  829)
* verbose option, mysqlimport:           mysqlimport.        (line  273)
* verbose option, mysqlshow:             mysqlshow.          (line  199)
* verbose option, mysqlslap:             mysqlslap.          (line  387)
* verbose option, perror:                perror.             (line   51)
* version option, comp_err:              comp-err.           (line   69)
* version option, my_print_defaults:     my-print-defaults.  (line   59)
* version option, myisamchk:             myisamchk-general-options.
                                                             (line   31)
* version option, myisampack:            myisampack.         (line  107)
* version option, mysql:                 mysql-command-options.
                                                             (line  475)
* version option, mysql_waitpid:         mysql-waitpid.      (line   35)
* version option, mysqlaccess:           mysqlaccess.        (line  151)
* version option, mysqladmin:            mysqladmin.         (line  403)
* version option, mysqlbinlog:           mysqlbinlog.        (line  299)
* version option, mysqlcheck:            mysqlcheck.         (line  358)
* version option, mysqld:                server-options.     (line 1497)
* version option, mysqld_multi:          mysqld-multi.       (line  157)
* version option, mysqldump:             mysqldump.          (line  833)
* version option, mysqlimport:           mysqlimport.        (line  277)
* version option, mysqlmanager:          instance-manager-command-options.
                                                             (line  238)
* version option, mysqlshow:             mysqlshow.          (line  205)
* version option, mysqlslap:             mysqlslap.          (line  393)
* version option, ndb_config:            mysql-cluster-utilities-ndb-config.
                                                             (line   25)
* version option, perror:                perror.             (line   56)
* version option, resolve_stack_dump:    resolve-stack-dump. (line   32)
* version option, resolveip:             resolveip.          (line   23)
* VERSION():                             information-functions.
                                                             (line  494)
* version, choosing:                     which-version.      (line   19)
* version, latest:                       getting-mysql.      (line    6)
* vertical option, mysql:                mysql-command-options.
                                                             (line  479)
* vertical option, mysqladmin:           mysqladmin.         (line  407)
* Vietnamese:                            faqs-cjk.           (line   80)
* view restrictions:                     view-restrictions.  (line    6)
* views <1>:                             create-view.        (line    6)
* views <2>:                             views.              (line   12)
* views:                                 ansi-diff-views.    (line    6)
* VIEWS, INFORMATION_SCHEMA table:       views-table.        (line    6)
* Views, limitations:                    view-restrictions.  (line  107)
* Views, privileges:                     view-restrictions.  (line  107)
* Views, problems:                       view-restrictions.  (line  107)
* views, updatable <1>:                  create-view.        (line    6)
* views, updatable:                      ansi-diff-views.    (line    6)
* virtual memory, problems while compiling: compilation-problems.
                                                             (line   38)
* Vision:                                myodbc-usagenotes-apptips-vision.
                                                             (line    6)
* Visual Objects:                        myodbc-usagenotes-apptips-microsoft-visualobjects.
                                                             (line    6)
* Visual Studio:                         windows-source-build-cmake.
                                                             (line    6)
* Visual Studio Plugin:                  connectors.         (line   15)
* WAIT COMPLETED (START BACKUP command): mysql-cluster-backup-using-management-client.
                                                             (line   53)
* wait option, myisamchk:                myisamchk-general-options.
                                                             (line   35)
* wait option, myisampack:               myisampack.         (line  111)
* wait option, mysql:                    mysql-command-options.
                                                             (line  485)
* wait option, mysqladmin:               mysqladmin.         (line  412)
* WAIT STARTED (START BACKUP command):   mysql-cluster-backup-using-management-client.
                                                             (line   44)
* wait-timeout option, mysqlmanager:     instance-manager-command-options.
                                                             (line  242)
* waiting for delay_list, thread state:  delayed-insert-thread-states.
                                                             (line   45)
* Waiting for event from ndbcluster, thread state: mysql-cluster-thread-states.
                                                             (line   25)
* Waiting for first event from ndbcluster, thread state: mysql-cluster-thread-states.
                                                             (line   30)
* waiting for handler insert, thread state: delayed-insert-thread-states.
                                                             (line   52)
* waiting for handler lock, thread state: delayed-insert-thread-states.
                                                             (line   57)
* waiting for handler open, thread state: delayed-insert-thread-states.
                                                             (line   63)
* Waiting for INSERT, thread state:      delayed-insert-thread-states.
                                                             (line   87)
* Waiting for master to send event, thread state: slave-io-thread-states.
                                                             (line   48)
* Waiting for master update, thread state: slave-io-thread-states.
                                                             (line   11)
* Waiting for ndbcluster binlog update to reach current position, thread state: mysql-cluster-thread-states.
                                                             (line   32)
* Waiting for ndbcluster to start, thread state: mysql-cluster-thread-states.
                                                             (line   34)
* Waiting for next activation, thread state: event-scheduler-thread-states.
                                                             (line   20)
* Waiting for scheduler to stop, thread state: event-scheduler-thread-states.
                                                             (line   25)
* Waiting for schema epoch, thread state: mysql-cluster-thread-states.
                                                             (line   36)
* Waiting for slave mutex on exit, thread state <1>: slave-sql-thread-states.
                                                             (line   31)
* Waiting for slave mutex on exit, thread state: slave-io-thread-states.
                                                             (line   82)
* Waiting for table, thread state:       general-thread-states.
                                                             (line  307)
* Waiting for tables, thread state:      general-thread-states.
                                                             (line  307)
* Waiting for the next event in relay log, thread state: slave-sql-thread-states.
                                                             (line    9)
* Waiting for the slave SQL thread to free enough relay log space, thread state: slave-io-thread-states.
                                                             (line   74)
* Waiting on cond, thread state:         general-thread-states.
                                                             (line  319)
* Waiting on empty queue, thread state:  event-scheduler-thread-states.
                                                             (line   30)
* Waiting to finalize termination, thread state: master-thread-states.
                                                             (line   29)
* Waiting to reconnect after a failed binlog dump request, thread state: slave-io-thread-states.
                                                             (line   36)
* Waiting to reconnect after a failed master event read, thread state: slave-io-thread-states.
                                                             (line   61)
* warnings command, mysql:               mysql-commands.     (line  217)
* WEEK():                                date-and-time-functions.
                                                             (line 1089)
* WEEKDAY():                             date-and-time-functions.
                                                             (line 1148)
* WEEKOFYEAR():                          date-and-time-functions.
                                                             (line 1158)
* Well-Known Binary format:              gis-wkb-format.     (line    6)
* Well-Known Text format:                gis-wkt-format.     (line    6)
* WHERE:                                 where-optimizations.
                                                             (line    6)
* where option, mysqldump:               mysqldump.          (line  837)
* WHERE, with SHOW <1>:                  extended-show.      (line    6)
* WHERE, with SHOW:                      information-schema. (line   36)
* WHILE:                                 while-statement.    (line    6)
* widths, display:                       data-types.         (line   31)
* Wildcard character (%):                string-syntax.      (line   57)
* Wildcard character (_):                string-syntax.      (line   58)
* wildcards, and LIKE:                   mysql-indexes.      (line  106)
* wildcards, in mysql.columns_priv table: request-access.    (line   57)
* wildcards, in mysql.db table:          request-access.     (line   27)
* wildcards, in mysql.host table:        request-access.     (line   27)
* wildcards, in mysql.procs_priv table:  request-access.     (line   57)
* wildcards, in mysql.tables_priv table: request-access.     (line   57)
* wildcards, in mysql.user table:        connection-access.  (line   29)
* Windows <1>:                           connector-net.      (line   15)
* Windows:                               myodbc-connector.   (line   17)
* Windows, compiling on:                 windows-client-compiling.
                                                             (line    6)
* Windows, open issues:                  windows-vs-unix.    (line  144)
* Windows, upgrading:                    windows-upgrading.  (line    6)
* Windows, versus Unix:                  windows-vs-unix.    (line    6)
* with-big-tables option:                configure-options.  (line    6)
* with-big-tables option, configure:     configure-options.  (line  491)
* with-debug option, configure:          configure-options.  (line  459)
* with-embedded-server option, configure: configure-options. (line  305)
* with-extra-charsets option, configure: configure-options.  (line  444)
* with-unix-socket-path option, configure: configure-options.
                                                             (line  329)
* with-zlib-dir option, configure:       configure-options.  (line  482)
* Within():                              functions-that-test-spatial-relationships-between-geometries.
                                                             (line   83)
* without-server option:                 configure-options.  (line    6)
* without-server option, configure:      configure-options.  (line  291)
* WKB format:                            gis-wkb-format.     (line    6)
* WKT format:                            gis-wkt-format.     (line    6)
* wrappers, Eiffel:                      eiffel.             (line    6)
* write access, tmp:                     mysql-install-db-problems.
                                                             (line   64)
* write-binlog option, mysqlcheck:       mysqlbinlog.        (line  303)
* write_buffer_size myisamchk variable:  myisamchk-general-options.
                                                             (line   45)
* Writing to net, thread state:          general-thread-states.
                                                             (line  324)
* X():                                   point-property-functions.
                                                             (line    9)
* X509/Certificate:                      secure-basics.      (line   31)
* XA BEGIN:                              xa-statements.      (line    6)
* XA COMMIT:                             xa-statements.      (line    6)
* XA PREPARE:                            xa-statements.      (line    6)
* XA RECOVER:                            xa-statements.      (line    6)
* XA ROLLBACK:                           xa-statements.      (line    6)
* XA START:                              xa-statements.      (line    6)
* XA transactions:                       xa.                 (line   11)
* XA transactions, transaction identifiers: xa-statements.   (line    6)
* xid, XA transaction identifier:        xa-statements.      (line    6)
* xml option, mysql:                     mysql-command-options.
                                                             (line  490)
* xml option, mysqldump:                 mysqldump.          (line  849)
* XOR, bitwise:                          bit-functions.      (line   36)
* XOR, logical:                          logical-operators.  (line   82)
* Y():                                   point-property-functions.
                                                             (line   22)
* yaSSL <1>:                             secure-using-ssl.   (line    6)
* yaSSL:                                 secure-connections. (line   14)
* Year 2000 compliance:                  y2k-issues.         (line    6)
* Year 2000 issues:                      y2k-issues.         (line    6)
* YEAR data type <1>:                    year.               (line    6)
* YEAR data type:                        date-and-time-type-overview.
                                                             (line   65)
* YEAR():                                date-and-time-functions.
                                                             (line 1167)
* YEARWEEK():                            date-and-time-functions.
                                                             (line 1174)
* Yen sign (Japanese):                   faqs-cjk.           (line   32)
* | (bitwise OR):                        bit-functions.      (line   18)
* || (logical OR):                       logical-operators.  (line   63)
* ~:                                     bit-functions.      (line   67)



Tag Table:
Node: Top167
Node: introduction2922
Node: manual-info5804
Node: manual-conventions8573
Node: what-is-mysql-ab13157
Node: what-is14903
Node: what-is-mysql15275
Node: history19684
Node: features20868
Node: roadmap30176
Node: mysql-nutshell31714
Node: mysql-6-0-plans38143
Node: information-sources41412
Node: mailing-lists42009
Node: mailing-list-use47207
Node: forums48309
Node: irc48856
Node: mysql-enterprise-information49816
Node: bug-reports50607
Node: compatibility68076
Node: standards70792
Node: sql-mode71102
Node: ansi-mode72056
Node: extensions-to-ansi73247
Node: differences-from-ansi82579
Node: ansi-diff-select-into-table83715
Node: ansi-diff-transactions84579
Node: ansi-diff-triggers93445
Node: ansi-diff-foreign-keys93907
Node: ansi-diff-views98585
Node: ansi-diff-comments99486
Node: constraints102114
Node: constraint-primary-key104296
Node: constraint-invalid-data105695
Node: constraint-enum111343
Node: installing113742
Node: general-installation-issues117817
Node: which-os119791
Node: which-version123994
Node: choosing-version124809
Node: choosing-distribution-format131621
Node: many-versions134868
Node: mysql-binaries136800
Node: getting-mysql154394
Node: verifying-package-integrity155023
Node: verifying-md5-checksum156410
Node: checking-gpg-signature158108
Node: checking-rpm-signature162928
Node: installation-layouts164317
Node: quick-standard-installation168138
Node: windows-installation168951
Node: windows-choosing-package174770
Node: windows-using-installer176629
Node: windows-install-wizard177466
Node: mysql-install-wizard-introduction178229
Node: mysql-install-wizard-starting180523
Node: mysql-install-wizard-install-type182226
Node: mysql-install-wizard-custom-install183651
Node: mysql-install-wizard-confirmation-dialog184661
Node: mysql-install-wizard-changes185907
Node: mysql-install-wizard-upgrading189722
Node: windows-config-wizard190556
Node: mysql-config-wizard-introduction191796
Node: mysql-config-wizard-starting192792
Node: mysql-config-wizard-maintenance194120
Node: mysql-config-wizard-configuration-type195426
Node: mysql-config-wizard-server-type197121
Node: mysql-config-wizard-database-usage198733
Node: mysql-config-wizard-tablespace200869
Node: mysql-config-wizard-connections201900
Node: mysql-config-wizard-networking203293
Node: mysql-config-wizard-character-set204515
Node: mysql-config-wizard-service205665
Node: mysql-config-wizard-security207722
Node: mysql-config-wizard-confirmation208887
Node: mysql-config-wizard-file-location210611
Node: mysql-config-wizard-editing211520
Node: windows-install-archive212264
Node: windows-extract-archive212943
Node: windows-create-option-file214121
Node: windows-select-server217596
Node: windows-server-first-start219928
Node: windows-start-command-line223529
Node: windows-start-service225603
Node: windows-testing234062
Node: windows-troubleshooting235575
Node: windows-upgrading240588
Node: windows-vs-unix243485
Node: linux-rpm249352
Node: mac-os-x-installation258394
Node: solaris-installation265595
Node: netware-installation267064
Node: installing-binary272521
Node: installing-source281160
Node: quick-install284646
Node: configure-options291885
Node: installing-source-tree323641
Node: compilation-problems332018
Node: mit-pthreads339910
Node: windows-source-build343867
Node: windows-source-build-cmake347741
Node: windows-client-compiling355711
Node: post-installation356470
Node: windows-post-installation357985
Node: unix-post-installation363083
Node: mysql-install-db-problems374030
Node: automatic-start380116
Node: starting-server386873
Node: default-privileges394256
Node: upgrade402475
Node: upgrading-from-5-0407678
Node: upgrading-to-arch432842
Node: downgrading435904
Node: downgrading-to-5-0438032
Node: operating-system-specific-notes440026
Node: linux440472
Node: linux-os441721
Node: binary-notes-linux442640
Node: source-notes-linux446181
Node: linux-post-install452027
Node: linux-x86458489
Node: linux-sparc460940
Node: linux-alpha461321
Node: linux-powerpc462881
Node: linux-mips463125
Node: linux-ia-64463436
Node: selinux464382
Node: mac-os-x465180
Node: mac-os-x-10-x465581
Node: mac-os-x-server466876
Node: solaris467403
Node: solaris-2-7474365
Node: solaris-x86476638
Node: bsd-notes477505
Node: freebsd478064
Node: netbsd483155
Node: openbsd483410
Node: bsdi483707
Node: bsdi3484591
Node: bsdi4485906
Node: other-unix-notes487102
Node: hp-ux-10-20487845
Node: hp-ux-11-x489492
Node: ibm-aix492947
Node: sunos498804
Node: alpha-dec-unix499456
Node: alpha-dec-osf1502318
Node: sgi-irix505688
Node: sco508436
Node: sco-openserver520671
Node: sco-unixware527158
Node: environment-variables531244
Node: perl-support534151
Node: perl-installation535461
Node: activestate-perl538378
Node: perl-support-problems539556
Node: tutorial545107
Node: connecting-disconnecting547097
Node: entering-queries549780
Node: database-use558255
Node: creating-database561387
Node: creating-tables563647
Node: loading-tables567939
Node: retrieving-data571359
Node: selecting-all572552
Node: selecting-rows574667
Node: selecting-columns578454
Node: sorting-rows580602
Node: date-calculations583513
Node: working-with-null591145
Node: pattern-matching593704
Node: counting-rows601195
Node: multiple-tables605269
Node: getting-information610547
Node: batch-mode613475
Node: examples616566
Node: example-maximum-column618755
Node: example-maximum-row619111
Node: example-maximum-column-group619918
Node: example-maximum-column-group-row620457
Node: example-user-variables622135
Node: example-foreign-keys623228
Node: searching-on-two-keys627519
Node: calculating-days628422
Node: example-auto-increment629599
Node: twin633651
Node: twin-pool634542
Node: twin-event639457
Node: apache640417
Node: programs641311
Node: programs-overview642383
Node: programs-using653136
Node: invoking-programs653552
Node: connecting656972
Node: program-options665696
Node: command-line-options668657
Node: option-modifiers673748
Node: option-files675725
Node: option-file-options686242
Ref: option_no-defaults687020
Ref: option_print-defaults687078
Ref: option_defaults-file687186
Ref: option_defaults-extra-file687408
Ref: option_defaults-group-suffix687703
Node: option-files-preconfigured688109
Node: program-variables689106
Node: option-defaults-equals692269
Node: setting-environment-variables699346
Node: programs-server702334
Node: mysqld702960
Node: mysqld-safe704375
Ref: option_mysqld_safe_help710142
Ref: option_mysqld_safe_autoclose710197
Ref: option_mysqld_safe_basedir710625
Ref: option_mysqld_safe_core-file-size710701
Ref: option_mysqld_safe_datadir710852
Ref: option_mysqld_safe_defaults-extra-file710914
Ref: option_mysqld_safe_defaults-file711206
Ref: option_mysqld_safe_ledir711395
Ref: option_mysqld_safe_log-error711556
Ref: option_mysqld_safe_mysqld711655
Ref: option_mysqld_safe_mysqld-version712061
Ref: option_mysqld_safe_nice712506
Ref: option_mysqld_safe_no-defaults712625
Ref: option_mysqld_safe_open-files-limit712754
Ref: option_mysqld_safe_pid-file712984
Ref: option_mysqld_safe_port713057
Ref: option_mysqld_safe_skip-kill-mysqld713275
Ref: option_mysqld_safe_socket713403
Ref: option_mysqld_safe_syslog713523
Ref: option_mysqld_syslog-tag713815
Ref: option_mysqld_safe_timezone714164
Ref: option_mysqld_safe_user714367
Node: mysql-server719370
Node: mysqld-multi721801
Ref: option_mysqld_verbose727786
Node: programs-installation733459
Node: comp-err734439
Node: make-win-bin-dist736528
Node: mysqlbug738672
Node: mysql-fix-privilege-tables739990
Node: mysql-install-db742540
Node: mysql-secure-installation745183
Node: mysql-tzinfo-to-sql746014
Node: mysql-upgrade747960
Ref: option_mysql_upgrade_debug-check751223
Ref: option_mysql_upgrade_debug-info751354
Node: programs-client752131
Node: mysql752881
Node: mysql-command-options754838
Ref: option_mysql_help763115
Ref: option_mysql_auto-rehash763176
Ref: option_mysql_batch763802
Ref: option_mysql_character-sets-dir764164
Ref: option_mysql_column-names764295
Ref: option_mysql_column-type-info764356
Ref: option_mysql_comments764559
Ref: option_mysql_compress764801
Ref: option_mysql_database764931
Ref: option_mysql_debug765044
Ref: option_mysql_debug-check765232
Ref: option_mysql_debug-info765363
Ref: option_mysql_default-character-set765681
Ref: option_mysql_delimiter765820
Ref: option_mysql_disable-named-commands765933
Ref: option_mysql_execute766296
Ref: option_mysql_force766506
Ref: option_mysql_host766573
Ref: option_mysql_html766668
Ref: option_mysql_ignore-spaces766717
Ref: option_mysql_line-numbers766913
Ref: option_mysql_local-infile767020
Ref: option_mysql_named-commands767601
Ref: option_mysql_no-auto-rehash767884
Ref: option_mysql_no-beep768050
Ref: option_mysql_no-named-commands768112
Ref: option_mysql_no-pager768205
Ref: option_mysql_no-tee768292
Ref: option_mysql_one-database768405
Ref: option_mysql_pager768608
Ref: option_mysql_password769037
Ref: option_mysql_pipe769500
Ref: option_mysql_port769706
Ref: option_mysql_prompt769802
Ref: option_mysql_protocol770003
Ref: option_mysql_quick770314
Ref: option_mysql_raw770534
Ref: option_mysql_reconnect771492
Ref: option_mysql_safe-updates771735
Ref: option_mysql_secure_auth772092
Ref: option_mysql_show-warnings772481
Ref: option_mysql_sigint-ignore772634
Ref: option_mysql_silent772733
Ref: option_mysql_skip-column-names773064
Ref: option_mysql_skip-line-numbers773215
Ref: option_mysql_socket773445
Ref: option_mysql_ssl773602
Ref: option_mysql_table773794
Ref: option_mysql_tee773961
Ref: option_mysql_unbuffered774142
Ref: option_mysql_user774211
Ref: option_mysql_verbose774316
Ref: option_mysql_version774573
Ref: option_mysql_vertical774642
Ref: option_mysql_wait774858
Ref: option_mysql_xml774968
Ref: option_mysql_connect_timeout776640
Ref: option_mysql_max_allowed_packet776749
Ref: option_mysql_max_join_size776878
Ref: option_mysql_select_limit777126
Node: mysql-commands777997
Node: mysql-server-side-help791815
Node: batch-commands794149
Node: mysql-tips795715
Node: vertical-query-results796133
Node: safe-updates797373
Node: mysql-reconnect799069
Node: mysqladmin800678
Ref: command_mysqladmin_db_name801333
Ref: command_mysqladmin_debug801400
Ref: option_mysqladmin_debug-check801607
Ref: option_mysqladmin_debug-info801738
Ref: command_mysqladmin_drop801898
Ref: command_mysqladmin_extended-status801980
Ref: command_mysqladmin_flush-hosts802282
Ref: command_mysqladmin_flush-logs802350
Ref: command_mysqladmin_flush-privileges802392
Ref: command_mysqladmin_flush-status802468
Ref: command_mysqladmin_flush-tables802520
Ref: command_mysqladmin_flush-threads802566
Ref: command_mysqladmin_kill802619
Ref: command_mysqladmin_old-password802752
Ref: command_mysqladmin_password803199
Ref: command_mysqladmin_ping803953
Ref: command_mysqladmin_processlist804293
Ref: command_mysqladmin_reload804555
Ref: command_mysqladmin_refresh804602
Ref: command_mysqladmin_shutdown804672
Ref: command_mysqladmin_start-slave804713
Ref: command_mysqladmin_status804777
Ref: command_mysqladmin_stop-slave804838
Ref: command_mysqladmin_variables804900
Ref: command_mysqladmin_version805196
Ref: option_mysqladmin_help811706
Ref: option_mysqladmin_character-sets-dir811767
Ref: option_mysqladmin_compress811898
Ref: option_mysqladmin_count812028
Ref: option_mysqladmin_debug812164
Ref: option_mysqladmin_default-character-set812362
Ref: option_mysqladmin_force812501
Ref: option_mysqladmin_host812653
Ref: option_mysqladmin_no-beep812748
Ref: option_mysqladmin_password812936
Ref: option_mysqladmin_pipe813399
Ref: option_mysqladmin_port813605
Ref: option_mysqladmin_protocol813701
Ref: option_mysqladmin_relative814012
Ref: option_mysqladmin_silent814222
Ref: option_mysqladmin_sleep814319
Ref: option_mysqladmin_socket814591
Ref: option_mysqladmin_ssl814748
Ref: option_mysqladmin_user814940
Ref: option_mysqladmin_verbose815045
Ref: option_mysqladmin_version815142
Ref: option_mysqladmin_vertical815211
Ref: option_mysqladmin_wait815336
Ref: option_mysqladmin_connect_timeout815684
Ref: option_mysqladmin_shutdown_timeout815816
Node: mysqlcheck815944
Ref: option_mysqlcheck_help824842
Ref: option_mysqlcheck_all-databases824903
Ref: option_mysqlcheck_all-in-1825086
Ref: option_mysqlcheck_analyze825282
Ref: option_mysqlcheck_auto-repair825539
Ref: option_mysqlcheck_character-sets-dir825695
Ref: option_mysqlcheck_check825826
Ref: option_mysqlcheck_check-only-changed825915
Ref: coption_mysqlcheck_check-upgrade826058
Ref: option_mysqlcheck_compress826377
Ref: option_mysqlcheck_databases826501
Ref: option_mysqlcheck_debug826787
Ref: option_mysqlcheck_debug-check826937
Ref: option_mysqlcheck_debug-info827068
Ref: option_mysqlcheck_default-character-set827228
Ref: option_mysqlcheck_extended827367
Ref: option_mysqlcheck_fast827695
Ref: option_mysqlcheck_fix-db-names827777
Ref: option_mysqlcheck_fix-table-names827959
Ref: option_mysqlcheck_force828193
Ref: option_mysqlcheck_host828260
Ref: option_mysqlcheck_medium-check828355
Ref: option_mysqlcheck_optimized828540
Ref: option_mysqlcheck_password828593
Ref: option_mysqlcheck_pipe829056
Ref: option_mysqlcheck_port829262
Ref: option_mysqlcheck_protocol829358
Ref: option_mysqlcheck_quick829669
Ref: option_mysqlcheck_repair829996
Ref: option_mysqlcheck_silent830117
Ref: option_mysqlcheck_socket830187
Ref: option_mysqlcheck_ssl830344
Ref: option_mysqlcheck_tables830536
Ref: option_mysqlcheck_use-frm830678
Ref: option_mysqlcheck_user830874
Ref: option_mysqlcheck_verbose830979
Ref: option_mysqlcheck_version831094
Node: mysqldump831158
Ref: option_mysqldump_help846914
Ref: option_mysqldump_add-drop-database846975
Ref: option_mysqldump_add-drop-table847088
Ref: option_mysqldump_add-locks847187
Ref: option_mysqldump_all-databases847390
Ref: option_mysqldump_all-tablespaces847572
Ref: option_mysqldump_allow-keywords847914
Ref: option_mysqldump_character-sets-dir848063
Ref: option_mysqldump_comments848194
Ref: option_mysqldump_compact848437
Ref: option_mysqldump_compatible849043
Ref: option_mysqldump_complete-insert-option849961
Ref: option_mysqldump_compress850060
Ref: option_mysqldump_create-options850190
Ref: option_mysqldump_databases850302
Ref: option_mysqldump_debug850665
Ref: option_mysqldump_debug-check850868
Ref: option_mysqldump_debug-info850999
Ref: option_mysqldump_default-character-set851159
Ref: option_mysqldump_delayed-insert851532
Ref: option_mysqldump_delete-master-logs851631
Ref: option_mysqldump_disable-keys851820
Ref: option_mysqldump_dump-date852222
Ref: option_mysqldump_events852745
Ref: option_mysqldump_extended-insert852857
Ref: option_mysqldump_fields853061
Ref: option_mysqldump_first-slave853371
Ref: option_mysqldump_flush-logs853454
Ref: option_mysqldump_flush-privileges854114
Ref: option_mysqldump_force854450
Ref: option_mysqldump_host854983
Ref: option_mysqldump_hex-blob855120
Ref: option_mysqldump_ignore-table855316
Ref: option_mysqldump_insert-ignore855526
Ref: option_mysqldump_lines-terminated-by855609
Ref: option_mysqldump_lock-all-tables855801
Ref: option_mysqldump_lock-tables856058
Ref: option_mysqldump_log-error856733
Ref: option_mysqldump_master-data856860
Ref: option_mysqldump_no-autocommit859537
Ref: option_mysqldump_no-create-db859678
Ref: option_mysqldump_no-create-info859881
Ref: option_mysqldump_no-data859997
Ref: option_mysqldump_opt860205
Ref: option_mysqldump_order-by-primary860783
Ref: option_mysqldump_password861069
Ref: option_mysqldump_pipe861532
Ref: option_mysqldump_port861738
Ref: option_mysqldump_protocol861834
Ref: option_mysqldump_quick862145
Ref: option_mysqldump_quote-names862412
Ref: option_mysqldump_replace862807
Ref: option_mysqldump_result-file862926
Ref: option_mysqldump_routines863315
Ref: option_mysqldump_set-charset864635
Ref: option_mysqldump_single-transaction864827
Ref: option_mysqldump_skip-comments866458
Ref: option_mysqldump_skip-opt866538
Ref: option_mysqldump_socket866608
Ref: option_mysqldump_ssl866765
Ref: option_mysqldump_tab866957
Ref: option_mysqldump_tables868132
Ref: option_mysqldump_tz-utc868417
Ref: option_mysqldump_user869034
Ref: option_mysqldump_verbose869139
Ref: option_mysqldump_version869236
Ref: option_mysqldump_where869305
Ref: option_mysqldump_xml869661
Ref: option_mysqldump_net_buffer_length872795
Node: mysqlimport876210
Ref: option_mysqlimport_help882838
Ref: option_mysqlimport_character-sets-dir882899
Ref: option_mysqlimport_columns883030
Ref: option_mysqlimport_compress883257
Ref: option_mysqlimport_debug883387
Ref: option_mysqlimport_debug-check883531
Ref: option_mysqlimport_debug-info883662
Ref: option_mysqlimport_default-character-set883822
Ref: option_mysqlimport_delete883961
Ref: option_mysqlimport_fields884039
Ref: option_mysqlimport_force884310
Ref: option_mysqlimport_host884527
Ref: option_mysqlimport_ignore884664
Ref: option_mysqlimport_ignore-lines884742
Ref: option_mysqlimport_lines-terminated-by884817
Ref: option_mysqlimport_local885239
Ref: option_mysqlimport_lock-tables885554
Ref: option_mysqlimport_low-priority885719
Ref: option_mysqlimport_password885902
Ref: option_mysqlimport_pipe886365
Ref: option_mysqlimport_port886571
Ref: option_mysqlimport_protocol886667
Ref: option_mysqlimport_replace886978
Ref: option_mysqlimport_silent887492
Ref: option_mysqlimport_socket887574
Ref: option_mysqlimport_ssl887731
Ref: option_mysqlimport_user887923
Ref: option_mysqlimport_use-threads888028
Ref: option_mysqlimport_verbose888142
Ref: option_mysqlimport_version888239
Node: mysqlshow889098
Ref: option_mysqlshow_help894594
Ref: option_mysqlshow_character-sets-dir894655
Ref: option_mysqlshow_compress894786
Ref: option_mysqlshow_count894916
Ref: option_mysqlshow_debug895021
Ref: option_mysqlshow_debug-check895165
Ref: option_mysqlshow_debug-info895296
Ref: option_mysqlshow_default-character-set895456
Ref: option_mysqlshow_host895595
Ref: option_mysqlshow_keys895690
Ref: option_mysqlshow_password895738
Ref: option_mysqlshow_pipe896316
Ref: option_mysqlshow_port896522
Ref: option_mysqlshow_protocol896618
Ref: option_mysqlshow_show-table-type896929
Ref: option_mysqlshow_socket897076
Ref: option_mysqlshow_ssl897233
Ref: option_mysqlshow_status897425
Ref: option_mysqlshow_user897499
Ref: option_mysqlshow_verbose897604
Ref: option_mysqlshow_version897789
Node: mysqlslap897853
Ref: option_mysqlslap_help906893
Ref: option_mysqlslap_auto-generate-sql906954
Ref: option_mysqlslap_auto-generate-sql-add-autoincrement907098
Ref: option_mysqlslap_auto-generate-sql-execute-number907261
Ref: option_mysqlslap_auto-generate-sql-guid-primary907409
Ref: option_mysqlslap_auto-generate-sql-load-type907565
Ref: option_mysqlslap_auto-generate-sql-secondary-indexes907912
Ref: option_mysqlslap_auto-generate-sql-unique-query-number908121
Ref: option_mysqlslap_auto-generate-sql-unique-write-number908510
Ref: option_mysqlslap_auto-generate-sql-write-number908714
Ref: option_mysqlslap_commit908876
Ref: option_mysqlslap_compress909036
Ref: option_mysqlslap_concurrency909166
Ref: option_mysqlslap_create909281
Ref: option_mysqlslap_create-schema909391
Ref: option_mysqlslap_csv909509
Ref: option_mysqlslap_debug909722
Ref: option_mysqlslap_debug-check909866
Ref: option_mysqlslap_debug-info909997
Ref: option_mysqlslap_delimiter910163
Ref: option_mysqlslap_detach910290
Ref: option_mysqlslap_engine910481
Ref: option_mysqlslap_host910582
Ref: option_mysqlslap_iterations910677
Ref: option_mysqlslap_lock-directory910753
Ref: option_mysqlslap_number-char-cols910895
Ref: option_mysqlslap_number-int-cols911022
Ref: option_mysqlslap_number-of-queries911144
Ref: option_mysqlslap_only-print911284
Ref: option_mysqlslap_password911433
Ref: option_mysqlslap_pipe911902
Ref: option_mysqlslap_port912108
Ref: option_mysqlslap_post-query912204
Ref: option_mysqlslap_post-system912425
Ref: option_mysqlslap_pre-query912627
Ref: option_mysqlslap_pre-system912841
Ref: option_mysqlslap_preserve-schema913036
Ref: option_mysqlslap_protocol913233
Ref: option_mysqlslap_query913544
Ref: option_mysqlslap_silent913671
Ref: option_mysqlslap_slave913725
Ref: option_mysqlslap_socket913982
Ref: option_mysqlslap_ssl914139
Ref: option_mysqlslap_use-threads914331
Ref: option_mysqlslap_user914622
Ref: option_mysqlslap_verbose914727
Ref: option_mysqlslap_version914912
Node: programs-admin-utils914976
Node: innochecksum916552
Ref: option_innochecksum_count917074
Ref: option_innochecksum_debug917142
Ref: option_innochecksum_end917204
Ref: option_innochecksum_page917251
Ref: option_innochecksum_start917302
Ref: option_innochecksum_verbose917351
Node: myisam-ftdump917425
Ref: option_myisam_ftdump_help919132
Ref: option_myisam_ftdump_count919198
Ref: option_myisam_ftdump_dump919286
Ref: option_myisam_ftdump_length919371
Ref: option_myisam_ftdump_stats919433
Ref: option_myisam_ftdump_verbose919565
Node: myisamchk919652
Node: myisamchk-general-options931171
Ref: option_myisamchk_help931619
Ref: option_myisamchk_debug931680
Ref: option_myisamchk_silent931818
Ref: option_myisamchk_verbose931967
Ref: option_myisamchk_version932173
Ref: option_myisamchk_wait932242
Node: myisamchk-check-options936504
Ref: option_myisamchk_check936789
Ref: option_myisamchk_check-only-changed936949
Ref: option_myisamchk_extend-check937049
Ref: option_myisamchk_fast937528
Ref: option_myisamchk_force937609
Ref: option_myisamchk_information937814
Ref: option_myisamchk_medium-check937913
Ref: option_myisamchk_read-only938102
Ref: option_myisamchk_update-state938363
Node: myisamchk-repair-options938730
Ref: option_myisamchk_backup939013
Ref: option_myisamchk_character-sets-dir939100
Ref: option_myisamchk_correct-checksum939231
Ref: option_myisamchk_data-file-length939313
Ref: option_myisamchk_extended-check939444
Ref: option_myisamchk_keys-used939786
Ref: option_myisamchk_no-symlinks940198
Ref: option_myisamchk_max-record-length940464
Ref: option_myisamchk_parallel-recover940599
Ref: optionmyisamchk_quick940805
Ref: optionmyisamchk_recover941015
Ref: option_myisamchk_safe-recover941566
Ref: option_myisamchk_set-character-set942161
Ref: option_myisamchk_set-collation942320
Ref: option_myisamchk_sort-recover942497
Ref: option_myisamchk_tmpdir942640
Ref: option_myisamchk_unpack943120
Node: myisamchk-other-options943195
Ref: option_myisamchk_analyze943489
Ref: option_myisamchk_block-search944095
Ref: option_myisamchk_description944206
Ref: option_myisamchk_set-auto-increment944293
Ref: option_myisamchk_sort-index944662
Ref: option_myisamchk_sort-records944815
Node: myisamchk-memory945708
Node: myisamlog948091
Ref: option_myisamlog_help948908
Ref: option_myisamlog_files949009
Ref: option_myisamlog_information949071
Ref: option_myisamlog_offset949131
Ref: option_myisamlog_path949185
Ref: option_myisamlog_recovery949236
Ref: option_myisamlog_record-position949284
Ref: option_myisamlog_update949379
Ref: option_myisamlog_verbose949426
Ref: option_myisamlog_write949584
Ref: option_myisamlog_version949637
Node: myisampack949679
Ref: option_myisampack_help951458
Ref: option_myisampack_backup951519
Ref: option_myisampack_character-sets-dir951625
Ref: option_myisampack_debug951756
Ref: option_myisampack_force951900
Ref: option_myisampack_join952434
Ref: option_myisampack_silent953148
Ref: option_myisampack_test953228
Ref: option_myisampack_tmpdir953310
Ref: option_myisampack_verbose953439
Ref: option_myisampack_version953567
Ref: option_myisampack_wait953636
Node: mysqlaccess964506
Ref: option_mysqlaccess_help967868
Ref: option_mysqlaccess_brief967929
Ref: option_mysqlaccess_commit968006
Ref: option_mysqlaccess_copy968258
Ref: option_mysqlaccess_db968334
Ref: option_mysqlaccess_debug968403
Ref: option_mysqlaccess_host968486
Ref: option_mysqlaccess_howto968580
Ref: option_mysqlaccess_old_server968661
Ref: option_mysqlaccess_password968819
Ref: option_mysqlaccess_plan969168
Ref: option_mysqlaccess_preview969241
Ref: option_mysqlaccess_relnotes969354
Ref: option_mysqlaccess_rhost969407
Ref: option_mysqlaccess_rollback969503
Ref: option_mysqlaccess_spassword969589
Ref: option_mysqlaccess_superuser969961
Ref: option_mysqlaccess_table970068
Ref: option_mysqlaccess_user970131
Ref: option_mysqlaccess_version970225
Node: mysqlbinlog970789
Ref: option_mysqlbinlog_help977328
Ref: option_mysqlbinlog_base64-output977389
Ref: option_mysqlbinlog_character-sets-dir977630
Ref: option_mysqlbinlog_database977761
Ref: option_mysqlbinlog_debug978340
Ref: option_mysqlbinlog_debug-check978490
Ref: option_mysqlbinlog_debug-info978621
Ref: option_mysqlbinlog_disable-log-bin978781
Ref: option_mysqlbinlog_force-read979402
Ref: option_mysqlbinlog_hexdump979662
Ref: option_mysqlbinlog_host979890
Ref: option_mysqlbinlog_local-load979998
Ref: option_mysqlbinlog_offset980128
Ref: option_mysqlbinlog_password980199
Ref: option_mysqlbinlog_port980662
Ref: option_mysqlbinlog_position980773
Ref: option_mysqlbinlog_protocol980853
Ref: option_mysqlbinlog_read-from-remote-server981164
Ref: option_mysqlbinlog_result-file981628
Ref: option_mysqlbinlog_server-id981706
Ref: option_mysqlbinlog_set-charset981861
Ref: option_mysqlbinlog_short-form982073
Ref: option_mysqlbinlog_socket982193
Ref: option_mysqlbinlog_start-datetime982350
Ref: option_mysqlbinlog_stop-datetime982903
Ref: option_mysqlbinlog_start-position983214
Ref: option_mysqlbinlog_stop-position983419
Ref: option_mysqlbinlog_to-last-log983633
Ref: option_mysqlbinlog_user983960
Ref: option_mysqlbinlog_version984070
Ref: option_mysqlcheck-write-binlog984139
Ref: option_mysqlbinlog_open_files_limit984754
Node: mysqlhotcopy996715
Ref: option_mysqlhotcopy_help1000328
Ref: option_mysqlhotcopy_addtodest1000389
Ref: option_mysqlhotcopy_allowold1000492
Ref: option_mysqlhotcopy_checkpoint1000594
Ref: option_mysqlhotcopy_chroot1000726
Ref: option_mysqlhotcopy_debug1000906
Ref: option_mysqlhotcopy_dryrun1000950
Ref: option_mysqlhotcopy_flushlog1001020
Ref: option_mysqlhotcopy_host1001086
Ref: option_mysqlhotcopy_keepold1001310
Ref: option_mysqlhotcopy_method1001386
Ref: option_mysqlhotcopy_noindices1001464
Ref: option_mysqlhotcopy_password1001671
Ref: option_mysqlhotcopy_port1002073
Ref: option_mysqlhotcopy_quiet1002186
Ref: option_mysqlhotcopy_record_log_pos1002244
Ref: option_mysqlhotcopy_regexp1002383
Ref: option_mysqlhotcopy_resetmaster1002488
Ref: option_mysqlhotcopy_resetslave1002568
Ref: option_mysqlhotcopy_socket1002655
Ref: option_mysqlhotcopy_suffix1002743
Ref: option_mysqlhotcopy_tmpdir1002813
Ref: option_mysqlhotcopy_user1002890
Node: instance-manager1003963
Node: instance-manager-command-options1006797
Node: instance-manager-configuration-files1016058
Node: instance-manager-startup-process1019593
Node: instance-manager-security-passwords1024427
Node: instance-manager-security-monitoring1031050
Node: instance-manager-security1034716
Node: instance-manager-commands1035628
Node: mysql-convert-table-format1046737
Ref: option_mysql_convert_table_format_help1047731
Ref: option_mysql_convert_table_format_force1047792
Ref: option_mysql_convert_table_format_host1047846
Ref: option_mysql_convert_table_format_password1047941
Ref: option_mysql_convert_table_format_port1048344
Ref: option_mysql_convert_table_format_socket1048425
Ref: option_mysql_convert_table_format_type1048526
Ref: option_mysql_convert_table_format_user1048912
Ref: option_mysql_convert_table_format_verbose1049017
Ref: option_mysql_convert_table_format_version1049108
Node: mysql-find-rows1049166
Ref: option_mysql_find_rows_help1050165
Ref: option_mysql_find_rows_regexp1050237
Ref: option_mysql_find_rows_rows1050309
Ref: option_mysql_find_rows_skip-use-db1050366
Ref: option_mysql_find_rows_start_row1050450
Node: mysql-fix-extensions1050502
Node: mysql-setpermission1051391
Ref: option_mysql_setpermission_help1052539
Ref: option_mysql_setpermission_host1052594
Ref: option_mysql_setpermission_password1052673
Ref: option_mysql_setpermission_port1053061
Ref: option_mysql_setpermission_socket1053142
Ref: option_mysql_setpermission_user1053232
Node: mysql-waitpid1053316
Ref: option_mysql_waitpid_help1054291
Ref: option_mysql_waitpid_verbose1054358
Ref: option_mysql_waitpid_version1054486
Node: mysql-zap1054550
Ref: option_mysql_zap_help1055514
Ref: option_mysql_zap_force1055581
Ref: option_mysql_zap_test1055680
Node: programs-development1055768
Node: msql2mysql1057648
Node: mysql-config1058694
Node: my-print-defaults1061660
Ref: option_my_print_defaults_help1062596
Ref: option_my_print_defaults_config-file1062657
Ref: option_my_print_defaults_debug1062780
Ref: option_my_print_defaults_defaults-extra-file1062979
Ref: option_my_print_defaults_defaults-group-suffix1063173
Ref: option_my_print_defaults_no-defaults1063330
Ref: option_my_print_defaults_verbose1063389
Ref: option_my_print_defaults_version1063486
Node: resolve-stack-dump1063550
Ref: option_resolve_stack_dump_help1064329
Ref: option_resolve_stack_dump_numeric-dump-file1064390
Ref: option_resolve_stack_dump_symbols-file1064493
Ref: option_resolve_stack_dump_version1064577
Node: programs-miscellaneous1064641
Node: perror1065038
Ref: option_perror_help1066221
Ref: option_perror_ndb1066298
Ref: option_perror_silent1066375
Ref: option_perror_verbose1066448
Ref: option_perror_version1066558
Node: replace-utility1066622
Ref: option_replace_help1067995
Ref: option_replace_debug1068052
Ref: option_replace_silent1068101
Ref: option_replace_verbose1068178
Ref: option_replace_version1068262
Node: resolveip1068313
Ref: option_resolveip_help1068777
Ref: option_resolveip_silent1068853
Ref: option_resolveip_version1068917
Node: server-administration1068981
Node: mysqld-server1069831
Node: mysqld-option-tables1071041
Node: server-options1334378
Ref: option_mysqld_help1336410
Ref: option_mysqld_abort-slave-event-count1336553
Ref: option_mysqld_allow-suspicious-udfs1337425
Ref: option_mysqld_ansi1337930
Ref: option_mysqld_basedir1338158
Ref: option_mysqld_big-tables1338530
Ref: option_mysqld_bind-address1339162
Ref: option_mysqld_binlog-format1339398
Ref: option_mysqld_binlog-row-event-max-size1340755
Ref: option_mysqld_bootstrap1341226
Ref: option_mysqld_character-sets-dir1341529
Ref: option_mysqld_character-set-client-handshake1341903
Ref: option_mysqld_character-set-filesystem1342264
Ref: option_mysqld_character-set-server1342740
Ref: option_mysqld_chroot1343290
Ref: option_mysqld_collation-server1343635
Ref: option_mysqld_console1344014
Ref: option_mysqld_core-file1344322
Ref: option_mysqld_datadir1344714
Ref: option_mysqld_debug1345008
Ref: option_mysqld_default-character-set1346159
Ref: option_mysqld_default-collation1346467
Ref: option_mysqld_default-storage-engine1346856
Ref: option_mysqld_default-table-type1346991
Ref: option_mysqld_default-time-zone1347203
Ref: option_mysqld_delay-key-write1347558
Ref: option_mysqld_des-key-file1348543
Ref: option_mysqld_disconnect-slave-event-count1348704
Ref: option_mysqld_enable-named-pipe1348904
Ref: option_mysqld_enable-pstack1349389
Ref: option_mysqld_engine-condition-pushdown1349543
Ref: option_mysqld_event-scheduler1351175
Ref: option_mysqld_exit-info1351838
Ref: option_mysqld_external-locking1352105
Ref: option_mysqld_flush1352796
Ref: option_mysqld_gdb1353247
Ref: option_mysqld_general-log1353596
Ref: option_mysqld_init-file1354289
Ref: option_mysqld_language1354901
Ref: option_mysqld_large-pages1355453
Ref: option_mysqld_log1356606
Ref: option_mysqld_log-bin1357348
Ref: option_mysqld_log-bin-index1357932
Ref: option_mysqld_log-bin-trust-function-creators1358229
Ref: option_mysqld_log-error1358942
Ref: option_mysqld_log-isam1359418
Ref: option_mysqld_log-long-format1359591
Ref: option_mysqld_log-output1360123
Ref: option_mysqld_log-queries-not-using-indexes1361576
Ref: option_mysqld_log-short-format1362049
Ref: option_mysqld_log-slow-admin-statements1362331
Ref: option_mysqld_log-slow-queries1362580
Ref: option_mysqld_log-slow-slave-statements1363433
Ref: option_mysqld_log-tc1363799
Ref: option_mysqld_log-tc-size1364232
Ref: option_mysqld_log-warnings1364474
Ref: option_mysqld_low-priority-updates1365339
Ref: option_mysqld_min-examined-row-limit1366105
Ref: option_mysqld_max-binlog-dump-events1366588
Ref: option_mysqld_memlock1366782
Ref: option_mysqld_myisam-recover1368147
Ref: option_mysqld_old-passwords1370086
Ref: option_mysqld_old-style-user-limits1370581
Ref: option_mysqld_one-thread1370936
Ref: option_mysqld_open-files-limit1371291
Ref: option_mysqld_pid-file1372240
Ref: option_mysqld_port1372637
Ref: option_mysqld_port-open-timeout1373092
Ref: option_mysqld_safe-mode1373618
Ref: option_mysqld_safe-show-database1373707
Ref: option_mysqld_safe-user-create1374067
Ref: option_mysqld_secure-auth1374886
Ref: option_mysqld_secure-file-priv1375276
Ref: option_mysqld_shared-memory1375815
Ref: option_mysqld_shared-memory-base-name1375944
Ref: option_mysqld_skip-concurrent-insert1376163
Ref: option_mysqld_skip-external-locking1376401
Ref: option_mysqld_skip-grant-tables1376700
Ref: option_mysqld_skip-host-cache1377521
Ref: option_mysqld_skip-innodb1377714
Ref: option_mysqld_skip-name-resolve1377914
Ref: option_mysqld_skip-networking1378166
Ref: option_mysqld_sporadic-binlog-dump-fail1378485
Ref: option_mysqld_standalone1378903
Ref: option_mysqld_symbolic-links1379067
Ref: option_mysqld_skip-safemalloc1379888
Ref: option_mysqld_skip-show-database1380222
Ref: option_mysqld_skip-stack-trace1380899
Ref: option_mysqld_skip-thread-priority1381196
Ref: option_mysqld_slow-query-log1381292
Ref: option_mysqld_socket1382008
Ref: option_mysqld_sql-mode1382852
Ref: option_mysqld_sysdate-is-now1383813
Ref: option_mysqld_tc-heuristic-recover1384479
Ref: option_mysqld_temp-pool1384746
Ref: option_mysqld_transaction-isolation1385271
Ref: option_mysqld_tmpdir1385693
Ref: option_mysqld_user1386956
Ref: option_mysqld_version1388243
Node: server-system-variables1389274
Ref: option_mysqld_auto-increment-increment1419020
Ref: option_mysqld_auto-increment-offset1427261
Ref: option_mysqld_automatic_sp_privileges1427943
Ref: option_mysqld_back_log1428697
Ref: option_mysqld_binlog_cache_size1430405
Ref: option_mysqld_binlog_format1431528
Ref: option_mysqld_bulk_insert_buffer_size1434185
Ref: option_mysqld_character_set_client1434888
Ref: option_mysqld_character_set_connection1436312
Ref: option_mysqld_character_set_database1436643
Ref: option_mysqld_character_set_filesystem1437072
Ref: option_mysqld_character_set_results1438102
Ref: option_mysqld_character_set_server1438371
Ref: option_mysqld_character_set_system1438689
Ref: option_mysqld_character_sets_dir1438986
Ref: option_mysqld_collation_connection1439313
Ref: option_mysqld_collation_database1439561
Ref: option_mysqld_collation_server1439974
Ref: option_mysqld_completion_type1440276
Ref: option_mysqld_concurrent_insert1441196
Ref: option_mysqld_connect_timeout1442372
Ref: option_mysqld_date_format1443488
Ref: option_mysqld_datetime_format1443540
Ref: option_mysqld_default_week_format1444870
Ref: option_mysqld_delay_key_write1445275
Ref: option_mysqld_delayed_insert_limit1446781
Ref: option_mysqld_delayed_insert_timeout1447356
Ref: option_mysqld_delayed_queue_size1447786
Ref: option_mysqld_div_precision_increment1448360
Ref: option_mysqld_event_scheduler1449365
Ref: option_mysqld_expire_logs_days1450115
Ref: option_mysqld_flush_time1451154
Ref: option_mysqld_ft_boolean_syntax1452130
Ref: option_mysqld_ft_max_word_len1453209
Ref: option_mysqld_ft_min_word_len1453703
Ref: option_mysqld_ft_query_expansion_limit1454197
Ref: option_mysqld_ft_stopword_file1454647
Ref: option_mysqld_general_log1455428
Ref: option_mysqld_general_log_file1456182
Ref: option_mysqld_group_concat_max_len1456628
Ref: option_mysqld_have_archive1457068
Ref: option_mysqld_have_blackhole_engine1457202
Ref: option_mysqld_have_compress1457347
Ref: option_mysqld_have_crypt1457537
Ref: option_mysqld_have_csv1457693
Ref: option_mysqld_have_dynamic_loading1457775
Ref: option_mysqld_have_example_engine1457925
Ref: option_mysqld_have_federated_engine1458066
Ref: option_mysqld_have_geometry1458211
Ref: option_mysqld_have_innodb1458302
Ref: option_mysqld_have_isam1458418
Ref: option_mysqld_have_merge_engine1458640
Ref: option_mysqld_have_openssl1458801
Ref: option_mysqld_have_partitioning1458953
Ref: option_mysqld_have_query_cache1459123
Ref: option_mysqld_have_row_based_replication1459212
Ref: option_mysqld_have_raid1459748
Ref: option_mysqld_have_rtree_keys1459970
Ref: option_mysqld_have_ssl1460116
Ref: option_mysqld_have_symlink1460281
Ref: option_mysqld_hostname1460533
Ref: option_mysqld_init_connect1460855
Ref: option_mysqld_init_file1462338
Ref: option_mysqld_init_slave1463028
Ref: option_mysqld_interactive_timeout1463854
Ref: option_mysqld_join_buffer_size1464472
Ref: option_mysqld_keep_files_on_create1465528
Ref: option_mysqld_key_buffer_size1466682
Ref: option_mysqld_key_cache_age_threshold1469717
Ref: option_mysqld_key_cache_block_size1470318
Ref: option_mysqld_key_cache_division_limit1470764
Ref: option_mysqld_large_files_support1471722
Ref: option_mysqld_large_pages1471935
Ref: option_mysqld_large_page_size1472375
Ref: option_mysqld_lc_time_names1472880
Ref: option_mysqld_license1473591
Ref: option_mysqld_local_infile1473830
Ref: option_mysqld_locked_in_memory1474061
Ref: option_mysqld__log1474257
Ref: option_mysqld_log_bin1474375
Ref: option_mysqld_log_bin_trust_function_creators1474556
Ref: option_mysqld_log_error1475716
Ref: option_mysqld_log_output1475997
Ref: option_mysqld_log_queries_not_using_indexes1476985
Ref: option_mysqld_log_slave_updates1477449
Ref: option_mysqld_log_slow_queries1477725
Ref: option_mysqld_long_query_time1478666
Ref: option_mysqld_low_priority_updates1479789
Ref: option_mysqld_lower_case_file_system1480452
Ref: option_mysqld_lower_case_table_names1480952
Ref: option_mysqld_max_allowed_packet1482088
Ref: option_mysqld_max_binlog_cache_size1483037
Ref: option_mysqld_max_binlog_size1483668
Ref: option_mysqld_max_connect_errors1484625
Ref: option_mysqld_max_connections1485153
Ref: option_mysqld_max_delayed_threads1486455
Ref: option_mysqld_max_error_count1487282
Ref: option_mysqld_max_heap_table_size1487747
Ref: option_mysqld_max_insert_delayed_threads1488829
Ref: option_mysqld_max_join_size1489096
Ref: option_mysqld_max_length_for_sort_data1490415
Ref: option_mysqld_max_prepared_stmt_count1490893
Ref: option_mysqld_max_relay_log_size1492059
Ref: option_mysqld_max_seeks_for_key1493051
Ref: option_mysqld_max_sort_length1493818
Ref: option_mysqld_max_sp_recursion_depth1494299
Ref: option_mysqld_max_tmp_tables1495119
Ref: option_mysqld_max_user_connections1495562
Ref: option_mysqld_max_write_lock_count1496291
Ref: option_mysqld_min_examined_row_limit1496729
Ref: option_mysqld_myisam_block_size1497157
Ref: option_mysqld_myisam_data_pointer_size1497536
Ref: option_mysqld_myisam_max_sort_file_size1498100
Ref: option_mysqld_myisam_recover_options1498913
Ref: option_mysqld_myisam_repair_threads1499143
Ref: option_mysqld_myisam_sort_buffer_size1499739
Ref: option_mysqld_myisam_stats_method1500502
Ref: option_mysqld_myisam_use_mmap1501637
Ref: option_mysqld_named_pipe1502070
Ref: option_mysqld_net_buffer_length1502321
Ref: option_mysqld_net_read_timeout1503271
Ref: option_mysqld_net_retry_count1504069
Ref: option_mysqld_net_write_timeout1504590
Ref: option_mysqld_new1505160
Ref: option_mysqld_old1505617
Ref: option_mysqld_old_passwords1506540
Ref: option_mysqld_one_shot1506936
Ref: option_mysqld_open_files_limit1507076
Ref: option_mysqld_optimizer_prune_level1507729
Ref: option_mysqld_optimizer_search_depth1508359
Ref: option_mysqld_pid_file1509303
Ref: option_mysqld_plugin_dir1509653
Ref: option_mysqld_preload_buffer_size1510452
Ref: option_mysqld_prepared_stmt_count1510851
Ref: option_mysqld_protocol_version1511172
Ref: option_mysqld_query_alloc_block_size1511434
Ref: option_mysqld_query_cache_limit1511993
Ref: option_mysqld_query_cache_min_res_unit1512416
Ref: option_mysqld_query_cache_size1512962
Ref: option_mysqld_query_cache_type1513909
Ref: option_mysqld_query_cache_wlock_invalidate1515130
Ref: option_mysqld_query_prealloc_size1515938
Ref: option_mysqld_range_alloc_block_size1516644
Ref: option_mysqld_read_buffer_size1517060
Ref: option_mysqld_read_only1518042
Ref: option_mysqld_read_rnd_buffer_size1519808
Ref: option_mysqld_relay_log_purge1520896
Ref: option_mysqld_relay_log_space_limit1521326
Ref: option_mysqld_rpl-recovery-rank1522128
Ref: option_mysqld_secure_auth1522186
Ref: option_mysqld_secure_file_priv1523036
Ref: option_mysqld_server-id1523628
Ref: option_mysqld_shared_memory1524046
Ref: option_mysqld_shared_memory_base_name1524288
Ref: option_mysqld_skip-exernal-locking1524711
Ref: option_mysqld_skip_show_database1525240
Ref: option_mysqld_slave_exec_mode1526383
Ref: option_mysqld_slave_load_tmpdir1527189
Ref: option_mysqld_slave_net_timeout1527608
Ref: option_mysqld_slave_transaction_retries1528702
Ref: option_mysqld_slow_launch_time1529407
Ref: option_mysqld_slow_query_log1529807
Ref: option_mysqld_slow_query_log_file1530287
Ref: option_mysqld_sort_buffer_size1531670
Ref: option_mysqld_sql_mode1532413
Ref: option_mysqld_sql_slave_skip_counter1533394
Ref: option_mysqld_ssl-ca1533723
Ref: option_mysqld_ssl-capath1534094
Ref: option_mysqld_ssl-cert1534507
Ref: option_mysqld_ssl-cipher1534915
Ref: option_mysqld_ssl-key1535302
Ref: option_mysqld_storage_engine1535699
Ref: option_mysqld_sync_binlog1536055
Ref: option_mysqld_sync_frm1537227
Ref: option_mysqld_system_time_zone1537714
Ref: option_mysqld_table_cache1538602
Ref: option_mysqld_table_definition_cache1539083
Ref: option_mysqld_table_lock_wait_timeout1540119
Ref: option_mysqld_table_open_cache1540735
Ref: option_mysqld_table_type1541672
Ref: option_mysqld_thread_cache_size1542063
Ref: option_mysqld_thread_concurrency1543165
Ref: option_mysqld_thread_handling1543693
Ref: option_mysqld_thread_stack1544472
Ref: option_mysqld_time_format1545208
Ref: option_mysqld_time_zone1545260
Ref: option_mysqld_timed_mutexes1545800
Ref: option_mysqld_tmp_table_size1546510
Ref: option_mysqld_transaction_alloc_block_size1548770
Ref: option_mysqld_transaction_prealloc_size1549283
Ref: option_mysqld_tx_isolation1550231
Ref: option_mysqld_updatable_views_with_limit1551104
Ref: option_mysqld_version_comment1552086
Ref: option_mysqld_version_compile_machine1552289
Ref: option_mysqld_version_compile_os1552390
Ref: option_mysqld_wait_timeout1552643
Node: server-session-variables1553467
Ref: option_mysqld_autocommit1556133
Ref: option_mysqld_error_count1557231
Ref: option_mysqld_foreign_key_checks1557405
Ref: option_mysqld_identity1558321
Ref: option_mysqld_insert_id1558569
Ref: option_mysqld_last_insert_id1558773
Ref: option_mysqld_sql_auto_is_null1559111
Ref: option_mysqld_sql_big_selects1559426
Ref: option_mysqld_sql_buffer_result1559992
Ref: option_mysqld_sql_log_bin1560318
Ref: option_mysqld_sql_log_off1560518
Ref: option_mysqld_sql_log_update1560726
Ref: option_mysqld_sql_notes1560827
Ref: option_mysqld_sql_quote_show_create1561175
Ref: option_mysqld_sql_safe_updates1561559
Ref: option_mysqld_sql_select_limit1561930
Ref: option_mysqld_sql_warnings1562895
Ref: option_mysqld_timestamp1563125
Ref: option_mysqld_unique_checks1563759
Ref: option_mysqld_warning_count1564383
Node: using-system-variables1564577
Node: structured-system-variables1576326
Node: dynamic-system-variables1581502
Node: server-status-variables1602923
Ref: option_mysqld_Aborted_clients1635673
Ref: option_mysqld_Aborted_connects1635857
Ref: option_mysqld_Binlog_cache_disk_use1635990
Ref: option_mysqld_Binlog_cache_use1636224
Ref: option_mysqld_Bytes_received1636330
Ref: option_mysqld_Bytes_sent1636407
Ref: option_mysqld_Com_option_mysqld1636474
Ref: option_mysqld_Compression1638683
Ref: option_mysqld_Connections1638815
Ref: option_mysqld_Created_tmp_disk_tables1638922
Ref: option_mysqld_Created_tmp_files1639069
Ref: option_mysqld_Created_tmp_tables1639149
Ref: option_mysqld_Delayed_errors1639467
Ref: option_mysqld_Delayed_insert_threads1639609
Ref: option_mysqld_Delayed_writes1639702
Ref: option_mysqld_Flush_commands1639777
Ref: option_mysqld_Handler_commit1639850
Ref: option_mysqld_Handler_delete1639924
Ref: option_mysqld_Handler_prepare1640015
Ref: option_mysqld_Handler_read_first1640110
Ref: option_mysqld_Handler_read_key1640377
Ref: option_mysqld_Handler_read_next1640575
Ref: option_mysqld_Handler_read_prev1640798
Ref: option_mysqld_Handler_read_rnd1640963
Ref: option_mysqld_Handler_read_rnd_next1641292
Ref: option_mysqld_Handler_rollback1641615
Ref: option_mysqld_Handler_savepoint1641729
Ref: option_mysqld_Handler_savepoint_rollback1641828
Ref: option_mysqld_Handler_update1641948
Ref: option_mysqld_Handler_write1642029
Ref: option_mysqld_Innodb_buffer_pool_pages_data1642109
Ref: option_mysqld_Innodb_buffer_pool_pages_dirty1642208
Ref: option_mysqld_Innodb_buffer_pool_pages_flushed1642291
Ref: option_mysqld_Innodb_buffer_pool_pages_free1642386
Ref: option_mysqld_Innodb_buffer_pool_pages_latched1642457
Ref: option_mysqld_Innodb_buffer_pool_pages_misc1642676
Ref: option_mysqld_Innodb_buffer_pool_pages_total1643021
Ref: option_mysqld_Innodb_buffer_pool_read_ahead_rnd1643112
Ref: option_mysqld_Innodb_buffer_pool_read_ahead_seq1643309
Ref: option_mysqld_Innodb_buffer_pool_read_requests1643485
Ref: option_mysqld_Innodb_buffer_pool_reads1643588
Ref: option_mysqld_Innodb_buffer_pool_wait_free1643748
Ref: option_mysqld_Innodb_buffer_pool_write_requests1644157
Ref: option_mysqld_Innodb_data_fsyncs1644258
Ref: option_mysqld_Innodb_data_pending_fsyncs1644335
Ref: option_mysqld_Innodb_data_pending_reads1644429
Ref: option_mysqld_Innodb_data_pending_writes1644507
Ref: option_mysqld_Innodb_data_read1644587
Ref: option_mysqld_Innodb_data_reads1644661
Ref: option_mysqld_Innodb_data_writes1644726
Ref: option_mysqld_Innodb_data_written1644793
Ref: option_mysqld_Innodb_dblwr_writes1644873
Ref: option_mysqld_Innodb_dblwr_pages_written1645004
Ref: option_mysqld_Innodb_log_waits1645150
Ref: option_mysqld_Innodb_log_write_requests1645305
Ref: option_mysqld_Innodb_log_writes1645380
Ref: option_mysqld_Innodb_os_log_fsyncs1645460
Ref: option_mysqld_Innodb_os_log_pending_fsyncs1645549
Ref: option_mysqld_Innodb_os_log_pending_writes1645646
Ref: option_mysqld_Innodb_os_log_written1645729
Ref: option_mysqld_Innodb_page_size1645811
Ref: option_mysqld_Innodb_pages_created1645997
Ref: option_mysqld_Innodb_pages_read1646062
Ref: option_mysqld_Innodb_pages_written1646121
Ref: option_mysqld_Innodb_row_lock_current_waits1646186
Ref: option_mysqld_Innodb_row_lock_time1646283
Ref: option_mysqld_Innodb_row_lock_time_avg1646381
Ref: option_mysqld_Innodb_row_lock_time_max1646478
Ref: option_mysqld_Innodb_row_lock_waits1646575
Ref: option_mysqld_Innodb_rows_deleted1646665
Ref: option_mysqld_Innodb_rows_inserted1646749
Ref: option_mysqld_Innodb_rows_read1646835
Ref: option_mysqld_Innodb_rows_updated1646913
Ref: option_mysqld_Key_blocks_not_flushed1646995
Ref: option_mysqld_Key_blocks_unused1647137
Ref: option_mysqld_Key_blocks_used1647375
Ref: option_mysqld_Key_read_requests1647576
Ref: option_mysqld_Key_reads1647668
Ref: option_mysqld_Key_write_requests1647919
Ref: option_mysqld_Key_writes1648011
Ref: option_mysqld_Last_query_cost1648091
Ref: option_mysqld_Max_used_connections1648634
Ref: option_mysqld_Not_flushed_delayed_rows1648772
Ref: option_mysqld_Open_files1648879
Ref: option_mysqld_Open_streams1648940
Ref: option_mysqld_Open_table_definitions1649031
Ref: option_mysqld_Open_tables1649149
Ref: option_mysqld_Opened_files1649212
Ref: option_mysqld_Opened_tables1649477
Ref: option_mysqld_Prepared_stmt_count1649635
Ref: option_mysqld_Qcache_free_blocks1649859
Ref: option_mysqld_Qcache_free_memory1649946
Ref: option_mysqld_Qcache_hits1650027
Ref: option_mysqld_Qcache_inserts1650086
Ref: option_mysqld_Qcache_lowmem_prunes1650164
Ref: option_mysqld_Qcache_not_cached1650289
Ref: option_mysqld_Qcache_queries_in_cache1650430
Ref: option_mysqld_Qcache_total_blocks1650522
Ref: option_mysqld_Questions1650604
Ref: option_mysqld_Rpl_status1650692
Ref: option_mysqld_Select_full_join1650777
Ref: option_mysqld_Select_full_range_join1650976
Ref: option_mysqld_Select_range1651081
Ref: option_mysqld_Select_range_check1651249
Ref: option_mysqld_Select_scan1651440
Ref: option_mysqld_Slave_open_temp_tables1651528
Ref: option_mysqld_Slave_retried_transactions1651648
Ref: option_mysqld_Slave_running1651799
Ref: option_mysqld_Slow_launch_threads1651949
Ref: option_mysqld_Slow_queries1652075
Ref: option_mysqld_Sort_merge_passes1652211
Ref: option_mysqld_Sort_range1652428
Ref: option_mysqld_Sort_rows1652503
Ref: option_mysqld_Sort_scan1652555
Ref: option_mysqld_Ssl_xxxx1652638
Ref: option_mysqld_Table_locks_immediate1652697
Ref: option_mysqld_Table_locks_waited1652821
Ref: option_mysqld_Tc_log_max_pages_used1653132
Ref: option_mysqld_Tc_log_page_size1653957
Ref: option_mysqld_Tc_log_page_waits1654237
Ref: option_mysqld_Threads_cached1654806
Ref: option_mysqld_Threads_connected1654879
Ref: option_mysqld_Threads_created1654954
Ref: option_mysqld_Threads_running1655212
Ref: option_mysqld_Uptime1655288
Node: server-sql-mode1655356
Node: server-side-help-support1675591
Node: server-signal-response1676983
Node: server-shutdown1678698
Node: log-files1682477
Node: log-tables1684734
Node: error-log1692726
Node: query-log1696260
Node: binary-log1700057
Ref: option_mysqld_binlog-do-db1705826
Ref: option_mysqld_binlog-ignore-db1706790
Node: binary-log-formats1715612
Node: binary-log-setting1717329
Node: binary-log-mixed1721973
Node: binary-log-mysql-database1729573
Node: slow-query-log1730971
Node: log-file-maintenance1734905
Node: security1738599
Node: security-guidelines1739552
Node: security-against-attack1748789
Node: privileges-options1755000
Ref: option_mysqld_local-infile1762888
Ref: option_mysqld_skip-merge1765731
Ref: option_mysqld_ssl_xxxx1766908
Node: load-data-local1767098
Node: changing-mysql-user1770496
Node: privilege-system1772735
Node: what-privileges1773616
Node: privileges1774203
Node: privileges-provided1788119
Node: connection-access1799554
Node: request-access1810897
Node: privilege-changes1819650
Node: access-denied1821372
Node: password-hashing1838738
Node: application-password-use1852655
Node: user-account-management1854098
Node: user-names1855204
Node: adding-users1860238
Node: removing-users1870993
Node: user-resources1871287
Node: passwords1877472
Node: password-security1880688
Node: secure-connections1884182
Node: secure-basics1885896
Node: secure-using-ssl1888206
Node: ssl-options1894629
Ref: option_mysqld_ssl-verify-server-cert1903092
Node: secure-create-certs1904004
Node: windows-and-ssh1913163
Node: multiple-servers1914858
Node: multiple-windows-servers1920396
Node: multiple-windows-command-line-servers1921423
Node: multiple-windows-services1924307
Node: multiple-unix-servers1929785
Node: multiple-server-clients1933505
Node: backup-and-recovery1936285
Node: backup1946985
Node: backup-strategy-example1952738
Node: backup-policy1956176
Node: recovery-from-backups1962771
Node: backup-strategy-summary1964549
Node: point-in-time-recovery1965545
Node: point-in-time-recovery-times1967387
Node: point-in-time-recovery-positions1969164
Node: table-maintenance1971429
Node: crash-recovery1973699
Node: check1976783
Node: repair1978441
Node: table-optimization1985446
Node: table-info1986435
Node: maintenance-schedule1999703
Node: optimization2002121
Node: optimize-overview2003167
Node: design-limitations2005211
Node: portability2006940
Node: internal-use2011106
Node: mysql-benchmarks2013485
Node: custom-benchmarks2015870
Node: query-speed2017933
Node: using-explain2021112
Node: estimating-performance2050144
Node: select-speed2052140
Node: where-optimizations2053766
Node: range-optimization2058425
Node: range-access-single-part2059087
Node: range-access-multi-part2063505
Node: index-merge-optimization2068265
Node: index-merge-intersection2071080
Node: index-merge-union2072717
Node: index-merge-sort-union2073772
Node: condition-pushdown-optimization2074534
Node: is-null-optimization2078979
Node: left-join-optimization2081105
Node: nested-joins2084071
Node: outer-join-simplification2097782
Node: order-by-optimization2103525
Node: group-by-optimization2112072
Node: loose-index-scan2113641
Node: tight-index-scan2116583
Node: distinct-optimization2118707
Node: in-subquery-optimization2120213
Node: limit-optimization2132475
Node: how-to-avoid-table-scan2134693
Node: information-schema-optimization2136872
Node: insert-speed2150692
Node: update-speed2156966
Node: delete-speed2157813
Node: miscellaneous-optimization-tips2158528
Node: locking-issues2169354
Node: internal-locking2170328
Node: table-locking2177265
Node: concurrent-inserts2182516
Node: external-locking2185044
Node: optimizing-database-structure2188591
Node: design2189360
Node: data-size2190908
Node: indexes2195692
Node: multiple-column-indexes2197698
Node: mysql-indexes2199674
Node: myisam-key-cache2208529
Node: shared-key-cache2212453
Node: multiple-key-caches2213277
Node: midpoint-insertion2218916
Node: index-preloading2221480
Node: key-cache-block-size2223252
Node: key-cache-restructuring2224322
Node: myisam-index-statistics2225698
Node: table-cache2231488
Node: creating-many-tables2237140
Node: optimizing-the-server2237763
Node: system-optimization2238637
Node: server-parameters2241100
Node: controlling-optimizer2256152
Node: query-cache2259182
Node: query-cache-how2261893
Node: query-cache-in-select2267670
Node: query-cache-configuration2268264
Node: query-cache-status-and-maintenance2274842
Node: thread-information2277613
Node: thread-commands2280132
Node: general-thread-states2282718
Node: delayed-insert-thread-states2292824
Node: master-thread-states2295785
Node: slave-io-thread-states2297111
Node: slave-sql-thread-states2300339
Node: slave-connection-thread-states2301667
Node: mysql-cluster-thread-states2302892
Node: event-scheduler-thread-states2303976
Node: compile-and-link-options2304925
Node: connection-threads2309414
Node: memory-use2312573
Node: internal-temporary-tables2318478
Node: dns2320587
Node: disk-issues2322127
Node: symbolic-links2326293
Node: symbolic-links-to-databases2327109
Node: symbolic-links-to-tables2328510
Node: windows-symbolic-links2332494
Node: language-structure2334532
Node: literals2335249
Node: string-syntax2335955
Node: number-syntax2342205
Node: hexadecimal-values2342802
Node: boolean-values2344393
Node: bit-field-values2344746
Node: null-values2346294
Node: identifiers2346881
Node: identifier-qualifiers2352013
Node: identifier-case-sensitivity2354153
Node: identifier-mapping2360233
Node: function-resolution2366554
Node: reserved-words2377108
Node: user-variables2384266
Node: comments2392222
Node: internationalization-localization2394752
Node: charset2395969
Node: charset-general2398134
Node: charset-mysql2400817
Node: charset-syntax2406054
Node: charset-server2407751
Node: charset-database2409869
Node: charset-table2412101
Node: charset-column2413530
Node: charset-literal2415091
Node: charset-national2419613
Node: charset-examples2420629
Node: charset-compatibility2422921
Node: charset-connection2423255
Node: charset-collations2430544
Node: charset-collate2431218
Node: charset-collate-precedence2432547
Node: charset-binary-op2432909
Node: charset-collate-tricky2435002
Node: charset-collation-charset2438525
Node: charset-collation-effect2439184
Node: charset-repertoire2442092
Node: charset-operations2447037
Node: charset-result2447530
Node: charset-convert2450511
Node: charset-show2451980
Node: charset-unicode2456541
Node: charset-metadata2460319
Node: charset-conversion2464430
Node: charset-charsets2468030
Node: charset-unicode-sets2472328
Node: charset-we-sets2477084
Node: charset-ce-sets2480954
Node: charset-se-me-sets2482543
Node: charset-baltic-sets2484143
Node: charset-cyrillic-sets2484967
Node: charset-asian-sets2486214
Node: charset-cp9322488590
Node: charset-configuration2495144
Node: german-character-set2498440
Node: error-message-language2499113
Node: adding-character-set2500450
Node: character-arrays2507086
Node: string-collating2510210
Node: multi-byte-characters2511187
Node: adding-collation2511992
Node: charset-collation-implementations2515012
Node: adding-collation-choosing-id2518796
Node: adding-collation-simple-8bit2520947
Node: adding-collation-unicode-uca2524600
Node: problems-with-character-sets2532668
Node: time-zone-support2534932
Node: locale-support2546997
Node: data-types2553768
Node: data-type-overview2555639
Node: numeric-type-overview2556044
Node: date-and-time-type-overview2565825
Node: string-type-overview2569478
Node: data-type-defaults2579475
Node: numeric-types2582513
Node: date-and-time-types2592304
Node: datetime2597559
Node: timestamp2606543
Node: time2615213
Node: year2618608
Node: y2k-issues2620211
Node: string-types2622828
Node: char2623533
Node: binary-varbinary2628740
Node: blob2632620
Node: enum2638136
Node: set2643864
Node: storage-requirements2649466
Node: choosing-types2658827
Node: other-vendor-data-types2659965
Node: functions2661982
Node: func-op-summary-ref2664810
Node: non-typed-operators2683736
Node: operator-precedence2686209
Node: type-conversion2687389
Node: comparison-operators2691377
Ref: operator_equal2694096
Ref: operator_equal-to2694409
Ref: operator_not-equal2694827
Ref: operator_less-than-or-equal2695055
Ref: operator_less-than2695151
Ref: operator_greater-than-or-equal2695234
Ref: operator_greater-than2695331
Ref: operator_is2695417
Ref: operator_is-not2695645
Ref: operator_is-null2695894
Ref: operator_is-not-null2696897
Ref: operator_between2697063
Ref: operator_not-between2698178
Ref: function_coalesce2698276
Ref: function_greatest2698551
Ref: function_in2699022
Ref: function_not-in2700603
Ref: function_isnull2700691
Ref: function_interval2701203
Ref: function_least2701747
Node: logical-operators2703087
Ref: operator_not2704002
Ref: operator_and2704530
Ref: operator_or2704998
Ref: operator_xor2705587
Node: control-flow-functions2706102
Ref: operator_case2706534
Ref: function_if2708048
Ref: function_ifnull2709988
Ref: function_nullif2711242
Node: string-functions2711627
Ref: function_ascii2716969
Ref: function_bin2717406
Ref: function_bit-length2717669
Ref: function_char2717815
Ref: function_char-length2719753
Ref: function_character-length2720043
Ref: function_concat2720135
Ref: function_concat-ws2720943
Ref: function_elt2721726
Ref: function_export-set2722123
Ref: function_field2722840
Ref: function_find-in-set2723556
Ref: function_format2724270
Ref: function_hex2724729
Ref: function_insert2725357
Ref: function_instr2726091
Ref: function_lcase2726587
Ref: function_left2726651
Ref: function_length2726855
Ref: function_load-file2727195
Ref: function_locate2727967
Ref: function_lower2728644
Ref: function_lpad2729595
Ref: function_ltrim2729947
Ref: function_make-set2730149
Ref: function_mid2730834
Ref: function_octet-length2730928
Ref: function_ord2731007
Ref: function_position2731517
Ref: function_quote2731621
Ref: function_repeat2732181
Ref: function_replace2732469
Ref: function_reverse2732837
Ref: function_right2733039
Ref: function_rpad2733285
Ref: function_rtrim2733677
Ref: function_soundex2733881
Ref: operator_sounds-like2735474
Ref: function_space2735568
Ref: function_substr2735708
Ref: function_substring2735866
Ref: function_substring-index2737293
Ref: function_trim2737986
Ref: function_ucase2738695
Ref: function_unhex2738759
Ref: function_upper2740378
Node: string-comparison-functions2740871
Ref: operator_like2741605
Ref: operator_not-like2745509
Ref: operator_not-regexp2746575
Ref: operator_regexp2746677
Ref: function_strcmp2748454
Node: regexp2749075
Node: numeric-functions2761522
Node: arithmetic-functions2764612
Ref: operator_plus2766574
Ref: operator_minus2766654
Ref: operator_unary-minus2766738
Ref: operator_times2767068
Ref: operator_divide2767551
Ref: operator_div2767882
Ref: operator_mod2768037
Node: mathematical-functions2768224
Ref: function_abs2770925
Ref: function_acos2771151
Ref: function_asin2771490
Ref: function_atan2772309
Ref: function_atan22772549
Ref: function_ceil2772956
Ref: function_ceiling2773018
Ref: function_conv2773408
Ref: function_cos2774246
Ref: function_cot2774382
Ref: function_crc322774562
Ref: function_degrees2774965
Ref: function_exp2775182
Ref: function_floor2775576
Ref: function_ln2776447
Ref: function_log2776847
Ref: function_log22777696
Ref: function_log102778041
Ref: function_mod2778343
Ref: function_oct2778948
Ref: function_pi2779208
Ref: function_pow2779538
Ref: function_power2779730
Ref: function_radians2779787
Ref: function_rand2779995
Ref: function_round2782303
Ref: function_sign2784705
Ref: function_sin2785017
Ref: function_sqrt2785233
Ref: function_tan2785497
Ref: function_truncate2785726
Node: date-and-time-functions2786431
Ref: function_adddate2792919
Ref: function_addtime2793676
Ref: function_convert-tz2794120
Ref: function_curdate2795303
Ref: function_current-date2795627
Ref: function_curtime2795739
Ref: function_current-time2796123
Ref: function_current-timestamp2796235
Ref: function_date2796368
Ref: function_datediff2796546
Ref: function_date-add2796997
Ref: function_date-format2804148
Ref: function_date-sub2807918
Ref: function_day2808005
Ref: function_dayname2808071
Ref: function_dayofmonth2808375
Ref: function_dayofweek2808641
Ref: function_dayofyear2808893
Ref: function_extract2809063
Ref: function_from-days2809699
Ref: function_from-unixtime2810037
Ref: function_get-format2811351
Ref: function_hour2813169
Ref: function_last-day2813549
Ref: function_localtime2814060
Ref: function_localtimestamp2814156
Ref: function_makedate2814272
Ref: function_maketime2814718
Ref: function_microsecond2814921
Ref: function_minute2815249
Ref: function_month2815409
Ref: function_monthname2815680
Ref: function_now2815991
Ref: function_period-add2817889
Ref: function_period-diff2818160
Ref: function_quarter2818453
Ref: function_second2818618
Ref: function_sec-to-time2818769
Ref: function_str-to-date2819209
Ref: function_subdate2820752
Ref: function_subtime2821517
Ref: function_sysdate2821962
Ref: function_time2824076
Ref: function_timediff2824383
Ref: function_timestamp2824909
Ref: function_timestampadd2825429
Ref: function_timestampdiff2826324
Ref: function_time-format2826870
Ref: function_time-to-sec2827466
Ref: function_to-days2827700
Ref: function_unix-timestamp2828665
Ref: function_utc-date2831374
Ref: function_utc-time2831673
Ref: function_utc-timestamp2831978
Ref: function_week2832350
Ref: function_weekday2834954
Ref: function_weekofyear2835222
Ref: function_year2835501
Ref: function_yearweek2835645
Node: mysql-calendar2836216
Node: fulltext-search2838100
Ref: function_match2838661
Node: fulltext-natural-language2841703
Node: fulltext-boolean2852584
Node: fulltext-query-expansion2859069
Node: fulltext-stopwords2862217
Node: fulltext-restrictions2869701
Node: fulltext-fine-tuning2871152
Node: cast-functions2877819
Ref: operator_binary2878229
Ref: function_cast2879183
Ref: function_convert2879393
Node: xml-functions2883886
Ref: function_extractvalue2890191
Ref: function_updatexml2896240
Node: other-functions2916671
Node: bit-functions2920869
Ref: operator_bitwise-or2921514
Ref: operator_bitwise-and2921649
Ref: operator_bitwise-xor2921785
Ref: operator_left-shift2922027
Ref: operator_right-shift2922198
Ref: operator_bitwise-invert2922370
Ref: function_bit-count2922508
Node: encryption-functions2922678
Ref: function_aes-decrypt2924486
Ref: function_aes-encrypt2924709
Ref: function_compress2926199
Ref: function_decode2927588
Ref: function_encode2927763
Ref: function_des-decrypt2928075
Ref: function_des-encrypt2928980
Ref: function_encrypt2931029
Ref: function_md52931853
Ref: function_old-password2932535
Ref: function_password2932998
Ref: function_sha12934014
Ref: function_uncompress2934738
Ref: function_uncompressed-length2935245
Node: information-functions2935470
Ref: function_benchmark2937051
Ref: function_charset2939480
Ref: function_coercibility2939786
Ref: function_collation2940760
Ref: function_connection-id2941006
Ref: function_current-user2941263
Ref: function_database2942464
Ref: function_found-rows2942988
Ref: function_last-insert-id2946515
Ref: function_row-count2954234
Ref: function_schema2955439
Ref: function_session-user2955508
Ref: function_system-user2955582
Ref: function_user2955654
Ref: function_version2956183
Node: miscellaneous-functions2956481
Ref: function_default2957888
Ref: function_get-lock2958289
Ref: function_inet-aton2960705
Ref: function_inet-ntoa2961671
Ref: function_is-free-lock2961907
Ref: function_is-used-lock2962177
Ref: function_master-pos-wait2962393
Ref: function_name-const2963377
Ref: function_release-lock2964064
Ref: function_sleep2964580
Ref: function_uuid2964817
Ref: function_uuid-short2967405
Ref: function_values2968474
Node: group-by-functions-and-modifiers2969231
Node: group-by-functions2969664
Ref: function_avg2972276
Ref: function_bit-and2972642
Ref: function_bit-or2972953
Ref: function_bit-xor2973159
Ref: function_count2973367
Ref: function_count-distinct2974562
Ref: function_group-concat2975057
Ref: function_max2977323
Ref: function_min2978169
Ref: function_std2979015
Ref: function_stddev2979268
Ref: function_stddev-pop2979543
Ref: function_stddev-samp2979820
Ref: function_sum2980007
Ref: function_var-pop2980283
Ref: function_var-samp2980627
Ref: function_variance2980823
Node: group-by-modifiers2981071
Node: group-by-hidden-fields2989026
Node: sql-syntax2991750
Node: sql-syntax-data-definition2992811
Node: alter-database2994097
Node: alter-logfile-group2997276
Node: alter-server3000067
Node: alter-table3000776
Node: alter-tablespace3039215
Node: create-database3042182
Node: create-index3044013
Node: create-logfile-group3053822
Node: create-server3056966
Node: create-table3059575
Node: silent-column-changes3113861
Node: create-tablespace3116388
Node: drop-database3121314
Node: drop-index3122947
Node: drop-logfile-group3124813
Node: drop-server3125762
Node: drop-table3126421
Node: drop-tablespace3128279
Node: rename-database3129229
Node: rename-table3130105
Node: sql-syntax-data-manipulation3132212
Node: delete3132928
Node: do3142559
Node: handler3143026
Node: insert3147557
Node: insert-select3160962
Node: insert-delayed3163136
Node: insert-on-duplicate3169947
Node: load-data3172572
Node: replace3199856
Node: select3202938
Node: join3223698
Node: index-hints3243038
Node: union3248484
Node: subqueries3253666
Node: scalar-subqueries3257247
Node: comparisons-using-subqueries3259388
Node: any-in-some-subqueries3260724
Node: all-subqueries3262745
Node: row-subqueries3264445
Node: exists-and-not-exists-subqueries3265917
Node: correlated-subqueries3267950
Node: unnamed-views3270054
Node: subquery-errors3276405
Node: optimizing-subqueries3278994
Node: rewriting-subqueries3283046
Node: truncate3284719
Node: update3287841
Node: sql-syntax-utility3293326
Node: describe3293725
Node: explain3295670
Node: help3296907
Node: use3302792
Node: sql-syntax-transactions3303761
Node: commit3304785
Node: cannot-roll-back3311228
Node: implicit-commit3311940
Node: savepoints3315449
Node: lock-tables3317543
Node: set-transaction3331571
Node: xa3335920
Node: xa-statements3341656
Node: xa-states3345918
Node: sql-syntax-server-administration3348605
Node: account-management-sql3349198
Node: create-user3350576
Node: drop-user3352045
Node: grant3353380
Node: rename-user3379057
Node: revoke3380064
Node: set-password3382237
Node: table-maintenance-sql3384520
Node: analyze-table3385133
Node: backup-table3387098
Node: check-table3388507
Node: checksum-table3395735
Node: optimize-table3396942
Node: repair-table3400233
Node: restore-table3405169
Node: plugin-sql3406349
Node: create-function-udf3406820
Node: drop-function-udf3409584
Node: install-plugin3410452
Node: uninstall-plugin3413536
Node: set-option3415159
Node: show3425190
Node: show-authors3429919
Node: show-binary-logs3430292
Node: show-binlog-events3430996
Node: show-character-set3432121
Node: show-collation3433391
Node: show-columns3435086
Node: show-contributors3439402
Node: show-create-database3439867
Node: show-create-event3440879
Node: show-create-procedure3442828
Node: show-create-table3444382
Node: show-create-trigger3445145
Node: show-create-view3446155
Node: show-databases3447409
Node: show-engine3448325
Ref: show-engine-ndb-status3452457
Node: show-engines3459277
Node: show-errors3463450
Node: show-events3464145
Node: show-grants3469863
Node: show-index3471712
Node: show-innodb-status3473762
Node: show-master-status3474071
Node: show-open-tables3474737
Node: show-plugins3476217
Node: show-privileges3477308
Node: show-procedure-code3478707
Node: show-procedure-status3480990
Node: show-processlist3482762
Node: show-scheduler-status3487831
Node: show-slave-hosts3489737
Node: show-slave-status3491244
Node: show-status3501868
Node: show-table-status3504988
Node: show-tables3509256
Node: show-triggers3510179
Node: show-variables3513012
Node: show-warnings3517673
Node: other-administrative-sql3522914
Node: cache-index3523370
Node: flush3525626
Node: kill3532302
Node: load-index3535039
Node: reset3537001
Node: sql-syntax-replication3537875
Node: replication-master-sql3538424
Node: purge-master-logs3539310
Node: reset-master3542059
Node: set-sql-log-bin3542394
Node: replication-slave-sql3542813
Node: change-master-to3543881
Node: load-data-from-master3552077
Node: load-table-from-master3555418
Node: master-pos-wait3557334
Node: reset-slave3557831
Node: set-global-sql-slave-skip-counter3558973
Node: start-slave3559487
Node: stop-slave3563221
Node: sql-syntax-prepared-statements3563843
Node: statement-repreparation3573091
Node: storage-engines3575159
Node: pluggable-storage-overview3576804
Ref: figure-storage-engine-architecture3577890
Node: pluggable-storage-common-layer3579230
Node: pluggable-storage3582624
Node: storage-engine-overview3584147
Node: storage-engine-choosing3587824
Node: storage-engine-compare-transactions3593749
Node: storage-engines-other3595608
Node: storage-engine-setting3598506
Node: myisam-storage-engine3601141
Node: myisam-start3607898
Node: key-space3618219
Node: myisam-table-formats3619337
Node: static-format3620407
Node: dynamic-format3622582
Node: compressed-format3625572
Node: myisam-table-problems3627396
Node: corrupted-myisam-tables3627956
Node: myisam-table-close3630213
Node: innodb3632655
Node: innodb-overview3634004
Node: innodb-contact-information3636944
Node: innodb-configuration3637631
Node: multiple-tablespaces3649933
Node: innodb-raw-devices3653891
Node: innodb-parameters3655829
Ref: option_mysqld_innodb3701406
Ref: option_mysqld_innodb_status_file3701564
Ref: option_mysqld_innodb_adaptive_hash_index3701828
Ref: option_mysqld_innodb_additional_mem_pool_size3702138
Ref: option_mysqld_innodb_autoextend_increment3702599
Ref: option_mysqld_innodb_buffer_pool_awe_mem_mb3702780
Ref: option_mysqld_innodb_autoinc_lock_mode3703696
Ref: option_mysqld_innodb_buffer_pool_size3704181
Ref: option_mysqld_innodb_checksums3704645
Ref: option_mysqld_innodb_commit_concurrency3705044
Ref: option_mysqld_innodb_concurrency_tickets3705240
Ref: option_mysqld_innodb_data_file_path3705936
Ref: option_mysqld_innodb_data_home_dir3706741
Ref: option_mysqld_innodb_doublewrite3707050
Ref: option_mysqld_innodb_fast_shutdown3707428
Ref: option_mysqld_innodb_file_io_threads3708008
Ref: option_mysqld_innodb_file_per_table3708307
Ref: option_mysqld_innodb_flush_log_at_trx_commit3708606
Ref: option_mysqld_innodb_flush_method3710992
Ref: option_mysqld_innodb_force_recovery3712445
Ref: option_mysqld_innodb_lock_wait_timeout3712894
Ref: option_mysqld_innodb_locks_unsafe_for_binlog3713983
Ref: option_mysqld_innodb_log_arch_dir3718038
Ref: option_mysqld_innodb_log_archive3718135
Ref: option_mysqld_innodb_log_buffer_size3718231
Ref: option_mysqld_innodb_log_file_size3718644
Ref: option_mysqld_innodb_log_files_in_group3719157
Ref: option_mysqld_innodb_log_group_home_dir3719334
Ref: option_mysqld_innodb_max_dirty_pages_pct3719593
Ref: option_mysqld_innodb_max_purge_lag3719870
Ref: option_mysqld_innodb_mirrored_log_groups3720949
Ref: option_mysqld_innodb_open_files3721103
Ref: option_mysqld_innodb_rollback_on_timeout3721578
Ref: option_mysqld_innodb_stats_on_metadata3721911
Ref: option_mysqld_innodb_support_xa3722654
Ref: option_mysqld_innodb_sync_spin_loops3723309
Ref: option_mysqld_innodb_table_locks3723453
Ref: option_mysqld_innodb_thread_concurrency3723813
Ref: option_mysqld_innodb_thread_sleep_delay3724812
Node: innodb-init3725677
Node: error-creating-innodb3728923
Node: using-innodb-tables3730424
Node: innodb-transactions-with-different-apis3732314
Node: converting-tables-to-innodb3734334
Node: innodb-auto-increment-handling3737237
Node: innodb-auto-increment-traditional3738181
Node: innodb-auto-increment-configurable3742140
Node: innodb-foreign-key-constraints3759107
Node: innodb-and-mysql-replication3775602
Node: adding-and-removing3780694
Node: innodb-backup3784740
Node: forcing-recovery3789744
Node: innodb-checkpoints3792702
Node: moving3794381
Node: innodb-transaction-model3795907
Node: innodb-lock-modes3797422
Node: innodb-and-autocommit3802488
Node: innodb-transaction-isolation3803678
Node: innodb-consistent-read3806673
Node: innodb-locking-reads3809431
Node: innodb-next-key-locking3813124
Node: innodb-consistent-read-example3816029
Node: innodb-locks-set3817829
Node: innodb-implicit-commit3823846
Node: innodb-deadlock-detection3824718
Node: innodb-deadlocks3826450
Node: innodb-tuning3829780
Node: innodb-monitor3837524
Node: innodb-multi-versioning3851353
Node: innodb-table-and-index3854621
Node: innodb-physical-structure3857096
Node: innodb-insert-buffering3857925
Node: innodb-adaptive-hash3859908
Node: innodb-physical-record3861051
Node: file-space-management3865444
Node: innodb-disk-io3865845
Node: innodb-file-space3867331
Node: innodb-file-defragmenting3869742
Node: innodb-error-handling3871430
Node: innodb-error-codes3874433
Node: operating-system-error-codes3876093
Node: innodb-restrictions3881728
Node: innodb-troubleshooting3890820
Node: innodb-troubleshooting-datadict3892627
Node: merge-storage-engine3896103
Node: merge-table-problems3905908
Node: memory-storage-engine3914135
Node: example-storage-engine3923085
Node: federated-storage-engine3924435
Node: federated-description3926142
Ref: figure-se-federated-structure3927808
Node: federated-create3929087
Node: federated-create-connection3930784
Node: federated-create-server3933333
Node: federated-usagenotes3936329
Node: federated-storage-engine-resources3941699
Node: archive-storage-engine3942117
Node: csv-storage-engine3946135
Node: se-csv-repair3948298
Node: se-csv-limitations3951312
Node: blackhole-storage-engine3952009
Node: ha-overview3955506
Ref: ha-availability-comparison3966415
Node: ha-drbd3968938
Ref: ha-drbd-overview3970549
Node: ha-drbd-install3971570
Node: ha-drbd-install-os3975451
Node: ha-drbd-install-drbd3981727
Node: ha-drbd-install-drbd-primary3983019
Node: ha-drbd-install-drbd-secondary3988298
Node: ha-drbd-install-drbd-using3990245
Node: ha-drbd-install-drbd-othercfg3993183
Node: ha-drbd-install-mysql3995025
Node: ha-drbd-performance3997552
Ref: ha-drbd-performance-sepinterface3998513
Node: ha-drbd-performance-bonded3999072
Node: ha-drbd-performance-syncrate4005018
Node: ha-heartbeat4007579
Ref: ha-heartbeat-overview4009678
Node: ha-heartbeat-config4010891
Node: ha-heartbeat-drbd4015392
Node: ha-heartbeat-drbd-dopd4019960
Node: ha-heartbeat-errors4022672
Node: ha-vm4023988
Node: ha-vm-commonissues4030503
Node: ha-vm-commonissues-performance4032181
Node: ha-vm-commonissues-storage4035906
Node: ha-vm-commonissues-networking4038341
Node: ha-vm-aws4039518
Node: ha-vm-aws-setup4042920
Node: ha-vm-aws-instance4046941
Node: ha-vm-aws-deploy4048948
Node: ha-vm-resources4053234
Node: ha-memcached4053775
Ref: ha-memcached-fig-overview4055846
Node: ha-memcached-install4057284
Node: ha-memcached-using4059956
Node: ha-memcached-using-deployment4064832
Node: ha-memcached-using-memory4067174
Ref: ha-memcached-fig-slabs4069415
Node: ha-memcached-using-namespaces4071344
Node: ha-memcached-using-expiry4072777
Node: ha-memcached-using-hashtypes4075034
Node: ha-memcached-interfaces4080109
Ref: ha-memcached-fig-basicflow4081970
Node: ha-memcached-interfaces-libmemcached4085091
Node: ha-memcached-interfaces-libmemcached-base4089267
Node: ha-memcached-interfaces-libmemcached-servers4090438
Node: ha-memcached-interfaces-libmemcached-set4093774
Node: ha-memcached-interfaces-libmemcached-get4098846
Node: ha-memcached-interfaces-libmemcached-behaviors4103473
Node: ha-memcached-interfaces-libmemcached-utilities4107626
Node: ha-memcached-interfaces-perl4109488
Node: ha-memcached-interfaces-python4116235
Node: ha-memcached-interfaces-php4122373
Node: ha-memcached-interfaces-ruby4129724
Node: ha-memcached-interfaces-java4132506
Node: ha-memcached-interfaces-mysqludf4136376
Node: ha-memcached-stats4141390
Node: ha-memcached-stats-general4147864
Node: ha-memcached-stats-slabs4151096
Node: ha-memcached-stats-items4154096
Node: ha-memcached-stats-sizes4155894
Node: ha-memcached-faq4157191
Ref: qandaitem-17-5-14161276
Ref: qandaitem-17-5-24162080
Ref: qandaitem-17-5-34162435
Ref: qandaitem-17-5-44163100
Ref: qandaitem-17-5-54163665
Ref: qandaitem-17-5-64164213
Ref: qandaitem-17-5-74164438
Ref: qandaitem-17-5-84164744
Ref: qandaitem-17-5-94166385
Ref: qandaitem-17-5-104166720
Ref: qandaitem-17-5-114167709
Ref: qandaitem-17-5-124168411
Ref: qandaitem-17-5-134168638
Ref: qandaitem-17-5-144168876
Ref: qandaitem-17-5-154169873
Ref: qandaitem-17-5-164170621
Ref: qandaitem-17-5-174172203
Ref: qandaitem-17-5-184172397
Ref: qandaitem-17-5-194173002
Ref: qandaitem-17-5-204173332
Ref: qandaitem-17-5-214173908
Ref: qandaitem-17-5-224174242
Ref: qandaitem-17-5-234174617
Ref: qandaitem-17-5-244174897
Ref: qandaitem-17-5-254175468
Ref: qandaitem-17-5-264175745
Ref: qandaitem-17-5-274176337
Ref: qandaitem-17-5-284176824
Ref: qandaitem-17-5-294176884
Ref: qandaitem-17-5-304177581
Node: mysql-proxy4177894
Node: mysql-proxy-platforms4180357
Node: mysql-proxy-install4181168
Node: mysql-proxy-install-binary4182190
Node: mysql-proxy-install-source4182709
Node: mysql-proxy-install-svn4184183
Node: mysql-proxy-cmdline4185863
Node: mysql-proxy-scripting4189993
Node: mysql-proxy-scripting-injection4194734
Node: mysql-proxy-scripting-structures4197536
Ref: mysql-proxy-scripting-structures-proxy4198185
Ref: mysql-proxy-scripting-structures-connection4199310
Ref: mysql-proxy-scripting-structures-backends4199771
Ref: mysql-proxy-scripting-structures-queries4200583
Ref: mysql-proxy-scripting-structures-response4201996
Ref: mysql-proxy-scripting-structures-resultset4204934
Ref: mysql-proxy-scripting-structures-return-states4206913
Ref: mysql-proxy-scripting-structures-packet-states4207736
Ref: mysql-proxy-scripting-structures-backend-states4208073
Ref: mysql-proxy-scripting-structures-command-constants4208728
Ref: mysql-proxy-scripting-structures-type-constants4210332
Node: mysql-proxy-scripting-connect-server4211566
Node: mysql-proxy-scripting-read-handshake4213057
Node: mysql-proxy-scripting-read-auth4214990
Node: mysql-proxy-scripting-read-auth-result4216622
Node: mysql-proxy-scripting-read-query4217798
Node: mysql-proxy-scripting-read-query-result4221228
Node: mysql-proxy-using4225566
Node: mysql-proxy-using-admin4228037
Node: mysql-proxy-faq4230046
Ref: qandaitem-18-6-14235445
Ref: qandaitem-18-6-24235672
Ref: qandaitem-18-6-34236025
Ref: qandaitem-18-6-44236335
Ref: qandaitem-18-6-54236580
Ref: qandaitem-18-6-64236753
Ref: qandaitem-18-6-74236940
Ref: qandaitem-18-6-84237179
Ref: qandaitem-18-6-94237581
Ref: qandaitem-18-6-104237876
Ref: qandaitem-18-6-114238068
Ref: qandaitem-18-6-124238262
Ref: qandaitem-18-6-134238500
Ref: qandaitem-18-6-144238702
Ref: qandaitem-18-6-154238883
Ref: qandaitem-18-6-164239156
Ref: qandaitem-18-6-174239359
Ref: qandaitem-18-6-184239640
Ref: qandaitem-18-6-194239921
Ref: qandaitem-18-6-204240152
Ref: qandaitem-18-6-214240391
Ref: qandaitem-18-6-224240727
Ref: qandaitem-18-6-234241041
Ref: qandaitem-18-6-244241370
Ref: qandaitem-18-6-254242187
Ref: qandaitem-18-6-264242400
Ref: qandaitem-18-6-274242571
Ref: qandaitem-18-6-284242832
Ref: qandaitem-18-6-294243167
Ref: qandaitem-18-6-304243341
Ref: qandaitem-18-6-314243709
Ref: qandaitem-18-6-324244046
Ref: qandaitem-18-6-334244252
Ref: qandaitem-18-6-344244466
Ref: qandaitem-18-6-354244592
Ref: qandaitem-18-6-364244886
Ref: qandaitem-18-6-374245004
Ref: qandaitem-18-6-384245302
Node: load-balancer4245544
Node: mysql-lb-installing4248766
Node: mysql-lb-getting-started4249836
Ref: mysql-lb-std14250995
Ref: mysql-lb-std24252183
Ref: mysql-lb-stdrepl4252941
Node: mysql-lb-using4255594
Node: mysql-lb-known-issues4258190
Node: load-balancer-faq4259219
Ref: qandaitem-19-5-14260176
Ref: qandaitem-19-5-24260598
Ref: qandaitem-19-5-34261064
Ref: qandaitem-19-5-44261412
Node: replication4261823
Node: replication-configuration4266163
Node: replication-howto4269899
Node: replication-howto-repuser4274184
Node: replication-howto-masterbaseconfig4275695
Node: replication-howto-slavebaseconfig4277416
Node: replication-howto-masterstatus4279000
Node: replication-howto-mysqldump4282391
Node: replication-howto-rawdata4284353
Node: replication-howto-newservers4287893
Node: replication-howto-existingdata4289644
Node: replication-howto-additionalslaves4294112
Node: replication-howto-slaveinit4297783
Node: replication-formats4298870
Node: replication-sbr-rbr4302731
Node: replication-rbr-usage4310809
Node: replication-options4317691
Ref: option_mysqld_log-slave-updates4322712
Ref: option_mysqld_log_warnings4323666
Ref: option_mysqld_master-connect-retry4324173
Ref: option_mysqld_master-host4324824
Ref: option_mysqld_master-info-file4325157
Ref: option_mysqld_master-password4325354
Ref: option_mysqld_master-port4325726
Ref: option_mysqld_master-retry-count4326064
Ref: option_mysqld_master-ssl4326669
Ref: option_mysqld_master-user4327353
Ref: option_mysqld_max-relay-log-size4327807
Ref: option_mysqld_read-only4327997
Ref: option_mysqld_relay-log4328276
Ref: option_mysqld_relay-log-index4328824
Ref: option_mysqld_relay-log-info-file4329043
Ref: option_mysqld_relay-log-purge4329250
Ref: option_mysqld_relay-log-space-limit4329524
Ref: option_mysqld_replicate-do-db4330742
Ref: option_mysqld_replicate-do-table4334852
Ref: option_mysqld_replicate-ignore-db4335181
Ref: option_mysqld_replicate-ignore-table4337220
Ref: option_mysqld_replicate-rewrite-db4337660
Ref: option_mysqld_replicate-same-server-id4338569
Ref: option_mysqld_replicate-wild-do-table4339338
Ref: option_mysqld_replicate-wild-ignore-table4341061
Ref: option_mysqld_report-host4341862
Ref: option_mysqld_report-port4342455
Ref: option_mysqld_report-password4342813
Ref: option_mysqld_report-user4343085
Ref: option_mysqld_show-slave-auth-info4343354
Ref: option_mysqld_skip-slave-start4343574
Ref: option_mysqld_slave_compressed_protocol4343755
Ref: option_mysqld_slave-load-tmpdir4343968
Ref: option_mysqld_slave-net-timeout4345151
Ref: option_mysqld_slave_skip_errors4345716
Node: replication-administration4347238
Node: replication-administration-status4348058
Node: replication-administration-pausing4353230
Node: replication-solutions4355102
Node: replication-solutions-backups4357388
Node: replication-solutions-backups-mysqldump4359386
Node: replication-solutions-backups-rawdata4361817
Node: replication-solutions-backups-read-only4364440
Node: replication-solutions-diffengines4368529
Node: replication-solutions-scaleout4372412
Ref: figure_replication-scaleout4373598
Node: replication-solutions-partitioning4375562
Ref: figure_replication-multi-db4376178
Node: replication-solutions-performance4377833
Ref: figure_replication-performance4378989
Node: replication-solutions-switch4381241
Ref: figure_replication-redundancy-before4382736
Ref: figure_replication-redundancy-after4385715
Node: replication-solutions-ssl4387007
Node: replication-notes4390509
Node: replication-features4391110
Node: replication-features-auto-increment4394704
Node: replication-features-charset4397389
Node: replication-features-create-select4399639
Node: replication-features-directory4402407
Node: replication-features-invoked4403307
Node: replication-features-floatvalues4407250
Node: replication-features-flush4407971
Node: replication-features-functions4409201
Node: replication-features-limit4414063
Node: replication-features-load-data4414757
Node: replication-features-mastercrash4415524
Node: replication-features-mastershutdown4416221
Node: replication-features-memory4417114
Node: replication-features-mysqldb4417789
Node: replication-features-reserved-words4418810
Node: replication-features-slaveerrors4420847
Node: replication-features-slaveshutdown4421670
Node: replication-features-temptables4422490
Node: replication-features-timeout4424685
Node: replication-features-timezone4425523
Node: replication-features-transactions4426551
Node: replication-features-differing-tables4429208
Node: replication-features-more-columns4430471
Node: replication-features-different-data-types4433967
Node: replication-features-variables4438920
Node: replication-features-views4440126
Node: replication-compatibility4440719
Node: replication-upgrade4442914
Node: replication-faq4445011
Ref: qandaitem-20-3-4-14446947
Ref: qandaitem-20-3-4-24447765
Ref: qandaitem-20-3-4-34448091
Ref: qandaitem-20-3-4-44449103
Ref: qandaitem-20-3-4-54450055
Ref: qandaitem-20-3-4-64451442
Ref: qandaitem-20-3-4-74452041
Ref: qandaitem-20-3-4-84452265
Ref: qandaitem-20-3-4-94455259
Ref: qandaitem-20-3-4-104455985
Ref: qandaitem-20-3-4-114456258
Ref: qandaitem-20-3-4-124456377
Ref: qandaitem-20-3-4-134456552
Ref: qandaitem-20-3-4-144456708
Node: replication-problems4456875
Node: replication-bugs4461754
Node: replication-implementation4464304
Node: replication-implementation-details4467091
Node: slave-logs4471538
Node: slave-logs-relaylog4473073
Node: slave-logs-status4475937
Node: replication-rules4480497
Node: mysql-cluster4489293
Node: mysql-cluster-overview4498320
Node: mysql-cluster-basics4500597
Node: mysql-cluster-nodes-groups4505512
Node: mysql-cluster-multi-computer4509857
Node: mysql-cluster-multi-hardware-software-network4516390
Node: mysql-cluster-multi-install4519708
Node: mysql-cluster-multi-config4527735
Node: mysql-cluster-multi-initial4533247
Node: mysql-cluster-multi-load-data-queries4535759
Node: mysql-cluster-multi-shutdown-restart4545127
Node: mysql-cluster-configuration4546647
Node: mysql-cluster-building4548428
Node: mysql-cluster-installing4550149
Node: mysql-cluster-quick4550988
Node: mysql-cluster-config-file4556239
Node: mysql-cluster-config-example4558483
Ref: mysql-cluster-config-ini-sections4563586
Node: mysql-cluster-connectstring4565890
Node: mysql-cluster-computer-definition4568749
Ref: id-computer-definition4569188
Ref: hostname-computer-definition4569351
Node: mysql-cluster-mgm-definition4569417
Ref: mysql-cluster-param-mgm-definition-id4570067
Ref: mysql-cluster-param-mgm-definition-executeoncomputer4570294
Ref: mysql-cluster-param-mgm-definition-portnumber4570444
Ref: mysql-cluster-param-mgm-definition-hostname4570589
Ref: mysql-cluster-param-mgm-definition-logdestination4570837
Ref: mysql-cluster-param-mgm-definition-arbitrationrank4572579
Ref: mysql-cluster-param-mgm-definition-arbitrationdelay4573528
Ref: mysql-cluster-param-mgm-definition-datadir4573780
Node: mysql-cluster-ndbd-definition4574254
Ref: mysql-cluster-identifying-data-nodes4575674
Ref: mysql-cluster-param-ndbd-definition-id4575823
Ref: mysql-cluster-param-ndbd-definition-executeoncomputer4576063
Ref: mysql-cluster-param-ndbd-definition-hostname4576188
Ref: mysql-cluster-param-ndbd-definition-serverport4576430
Ref: mysql-cluster-param-ndbd-definition-tcpbind-inaddr-any4576852
Ref: mysql-cluster-param-ndbd-definition-noofreplicas4577124
Ref: mysql-cluster-param-ndbd-definition-datadir4579188
Ref: mysql-cluster-param-ndbd-definition-filesystempath4579321
Ref: mysql-cluster-param-ndbd-definition-backupdatadir4579954
Ref: mysql-cluster-data-memory-index-memory-string-memory4580209
Ref: mysql-cluster-param-ndbd-definition-datamemory4580588
Ref: mysql-cluster-param-ndbd-definition-indexmemory4585787
Ref: mysql-cluster-param-ndbd-definition-stringmemory4586477
Ref: mysql-cluster-transaction-parameters4590710
Ref: mysql-cluster-param-ndbd-definition-maxnoofconcurrenttransactions4591375
Ref: mysql-cluster-param-ndbd-definition-maxnoofconcurrentoperations4592990
Ref: mysql-cluster-param-ndbd-definition-maxnooflocaloperations4595604
Ref: mysql-cluster-transaction-temporary-storage4596040
Ref: mysql-cluster-param-ndbd-definition-maxnoofconcurrentindexoperations4596660
Ref: mysql-cluster-param-ndbd-definition-maxnooffiredtriggers4597557
Ref: mysql-cluster-param-ndbd-definition-transactionbuffermemory4598461
Ref: mysql-cluster-scans-and-buffering4599347
Ref: mysql-cluster-param-ndbd-definition-maxnoofconcurrentscans4599840
Ref: mysql-cluster-param-ndbd-definition-maxnooflocalscans4601085
Ref: mysql-cluster-param-ndbd-definition-batchsizeperlocalscan4601404
Ref: mysql-cluster-param-ndbd-definition-longmessagebuffer4601671
Ref: mysql-cluster-memory-allocation4601926
Ref: mysql-cluster-param-ndbd-definition-maxallocate4601947
Ref: mysql-cluster-logging-and-checkpointing4602589
Ref: mysql-cluster-param-ndbd-definition-nooffragmentlogfiles4602658
Ref: mysql-cluster-param-ndbd-definition-fragmentlogfilesize4604814
Ref: mysql-cluster-param-ndbd-definition-maxnoofopenfiles4605554
Ref: mysql-cluster-param-ndbd-definition-initialnoofopenfiles4605795
Ref: mysql-cluster-param-ndbd-definition-maxnoofsavedmessages4605953
Ref: mysql-cluster-metadata-objects4606216
Ref: mysql-cluster-param-ndbd-definition-maxnoofattributes4606572
Ref: mysql-cluster-param-ndbd-definition-maxnooftables4607879
Ref: mysql-cluster-param-ndbd-definition-maxnooforderedindexes4608448
Ref: mysql-cluster-param-ndbd-definition-maxnoofuniquehashindexes4608881
Ref: mysql-cluster-param-ndbd-definition-maxnooftriggers4609327
Ref: mysql-cluster-param-ndbd-definition-maxnoofindexes4609870
Ref: mysql-cluster-boolean-parameters4610252
Ref: mysql-cluster-param-ndbd-definition-lockpagesinmainmemory4610499
Ref: mysql-cluster-param-ndbd-definition-stoponerror4611629
Ref: mysql-cluster-param-ndbd-definition-diskless4611842
Ref: mysql-cluster-param-ndbd-definition-odirect4612561
Ref: mysql-cluster-param-ndbd-definition-restartonerrorinsert4613079
Ref: mysql-cluster-param-ndbd-definition-compressedbackup4613335
Ref: mysql-cluster-param-ndbd-definition-compressedlcp4614035
Ref: mysql-cluster-timeouts-intervals-disk-paging4614748
Ref: mysql-cluster-param-ndbd-definition-timebetweenwatchdogcheck4615042
Ref: mysql-cluster-param-ndbd-definition-timebetweenwatchdogcheckinitial4615667
Ref: mysql-cluster-param-ndbd-definition-startpartialtimeout4616091
Ref: mysql-cluster-param-ndbd-definition-startpartitionedtimeout4616514
Ref: mysql-cluster-param-ndbd-definition-startfailuretimeout4616815
Ref: mysql-cluster-param-ndbd-definition-heartbeatintervaldbdb4617468
Ref: mysql-cluster-param-ndbd-definition-heartbeatintervaldbapi4618330
Ref: mysql-cluster-param-ndbd-definition-timebetweenlocalcheckpoints4619124
Ref: mysql-cluster-param-ndbd-definition-timebetweenglobalcheckpoints4620246
Ref: mysql-cluster-param-ndbd-definition-timebetweenepochs4621421
Ref: mysql-cluster-param-ndbd-definition-timebetweenepochstimeout4621849
Ref: mysql-cluster-param-ndbd-definition-maxbufferedepochs4622419
Ref: mysql-cluster-param-ndbd-definition-timebetweeninactivetransactionabortcheck4623354
Ref: mysql-cluster-param-ndbd-definition-transactioninactivetimeout4623723
Ref: mysql-cluster-param-ndbd-definition-transactiondeadlockdetectiontimeout4624168
Ref: mysql-cluster-param-ndbd-definition-disksyncsize4625280
Ref: mysql-cluster-param-ndbd-definition-diskcheckpointspeed4625840
Ref: mysql-cluster-param-ndbd-definition-diskcheckpointspeedinrestart4626073
Ref: mysql-cluster-param-ndbd-definition-noofdiskpagestodiskafterrestarttup4626348
Ref: mysql-cluster-param-ndbd-definition-noofdiskpagestodiskafterrestartacc4627850
Ref: mysql-cluster-param-ndbd-definition-noofdiskpagestodiskduringrestarttup4628330
Ref: mysql-cluster-param-ndbd-definition-noofdiskpagestodiskduringrestartacc4629134
Ref: mysql-cluster-param-ndbd-definition-arbitrationtimeout4629742
Ref: mysql-cluster-buffering-and-logging4630031
Ref: mysql-cluster-param-ndbd-definition-undoindexbuffer4630516
Ref: mysql-cluster-param-ndbd-definition-undodatabuffer4632230
Ref: mysql-cluster-param-ndbd-definition-redobuffer4633513
Ref: mysql-cluster-controlling-log-messages4634256
Ref: mysql-cluster-param-ndbd-definition-loglevelstartup4635041
Ref: mysql-cluster-param-ndbd-definition-loglevelshutdown4635178
Ref: mysql-cluster-param-ndbd-definition-loglevelstatistic4635325
Ref: mysql-cluster-param-ndbd-definition-loglevelcheckpoint4635564
Ref: mysql-cluster-param-ndbd-definition-loglevelnoderestart4635706
Ref: mysql-cluster-param-ndbd-definition-loglevelconnection4635832
Ref: mysql-cluster-param-ndbd-definition-loglevelerror4635979
Ref: mysql-cluster-param-ndbd-definition-loglevelcongestion4636223
Ref: mysql-cluster-param-ndbd-definition-loglevelinfo4636434
Ref: mysql-cluster-param-ndbd-definition-memreportfrequency4636593
Ref: mysql-cluster-backup-parameters4638002
Ref: mysql-cluster-param-ndbd-definition-backupdatabuffersize4638123
Ref: mysql-cluster-param-ndbd-definition-backuplogbuffersize4638770
Ref: mysql-cluster-param-ndbd-definition-backupmemory4640011
Ref: mysql-cluster-param-ndbd-definition-backupreportfrequency4640369
Ref: mysql-cluster-param-ndbd-definition-backupwritesize4640869
Ref: mysql-cluster-param-ndbd-definition-backupmaxwritesize4641050
Ref: mysql-cluster-realtime-performance-parameters4641529
Ref: mysql-cluster-param-ndbd-definition-lockexecutethreadtocpu4641767
Ref: mysql-cluster-param-ndbd-definition-lockmaintthreadstocpu4642018
Ref: mysql-cluster-param-ndbd-definition-realtimescheduler4642267
Ref: mysql-cluster-param-ndbd-definition-schedulerexecutiontimer4642432
Ref: mysql-cluster-param-ndbd-definition-schedulerspintimer4642619
Node: mysql-cluster-api-definition4642793
Ref: mysql-cluster-param-api-definition-id4643967
Ref: mysql-cluster-param-api-definition-executeoncomputer4644189
Ref: mysql-cluster-param-api-definition-hostname4644348
Ref: mysql-cluster-param-api-definition-arbitrationrank4645018
Ref: mysql-cluster-param-api-definition-arbitrationdelay4645695
Ref: mysql-cluster-param-api-definition-batchbytesize4645971
Ref: mysql-cluster-param-api-definition-batchsize4646711
Ref: mysql-cluster-param-api-definition-maxscanbatchsize4646842
Node: mysql-cluster-tcp-definition4647963
Ref: mysql-cluster-param-tcp-definition-nodeid4649332
Ref: mysql-cluster-param-tcp-definition-sendbuffermemory4649632
Ref: mysql-cluster-param-tcp-definition-sendsignalid4650211
Ref: mysql-cluster-param-tcp-definition-checksum4650525
Ref: mysql-cluster-param-tcp-definition-portnumber4650935
Ref: mysql-cluster-param-tcp-definition-receivebuffermemory4651123
Node: mysql-cluster-tcp-definition-direct4651472
Node: mysql-cluster-shm-definition4653344
Ref: mysql-cluster-param-shm-definition-nodeids4654348
Ref: mysql-cluster-param-shm-definition-shmkey4654524
Ref: mysql-cluster-param-shm-definition-shmsize4654743
Ref: mysql-cluster-param-shm-definition-sendsignalid4654982
Ref: mysql-cluster-param-shm-definition-checksum4655331
Node: mysql-cluster-sci-definition4655714
Ref: mysql-cluster-param-sci-definition-nodeids4656894
Ref: mysql-cluster-param-sci-definition-host1sciid04657070
Ref: mysql-cluster-param-sci-definition-host1sciid14657186
Ref: mysql-cluster-param-sci-definition-host2sciid04657446
Ref: mysql-cluster-param-sci-definition-host2sciid14657564
Ref: mysql-cluster-param-sci-definition-sharedbuffersize4657719
Ref: mysql-cluster-param-sci-definition-sendlimit4658147
Ref: mysql-cluster-param-sci-definition-sendsignalid4658494
Ref: mysql-cluster-param-sci-definition-checksum4658789
Node: mysql-cluster-config-params-overview4659167
Node: mysql-cluster-config-params-ndbd4662196
Node: mysql-cluster-config-params-mgm4681780
Node: mysql-cluster-config-params-api4684152
Node: mysql-cluster-config-lcp-params4686300
Node: mysql-cluster-options-variables4692517
Node: mysql-cluster-option-tables4693493
Node: mysql-cluster-mysqld-command-options4705927
Ref: option_mysqld_ndb-cluster-connection-pool4706821
Ref: option_mysqld_ndb-connectstring4708237
Ref: option_mysqld_ndbcluster4708425
Ref: option_mysqld_skip-ndbcluster4708759
Node: mysql-cluster-system-variables4709110
Ref: option_mysqld_have_ndbcluster4709695
Ref: option_mysqld_multi_range_count4709976
Ref: option_mysqld_ndb_autoincrement_prefetch_sz4710901
Ref: option_mysqld_ndb_cache_check_time4712155
Ref: option_mysqld_ndb_extra_logging4713013
Ref: option_mysqld_ndb_force_send4714058
Ref: option_mysqld_ndb_index_stat_cache_entries4714455
Ref: option_mysqld_ndb_index_stat_enable4714871
Ref: option_mysqld_ndb_index_stat_update_freq4715058
Ref: option_mysqld_ndb_optimized_node_selection4715378
Ref: option_mysqld_ndb_report_thresh_binlog_epoch_slip4717500
Ref: option_mysqld_ndb_report_thresh_binlog_mem_usage4717990
Ref: option_mysqld_ndb_use_copying_alter_table4718438
Ref: option_mysqld_ndb_use_exact_count4718812
Ref: option_mysqld_ndb_use_transactions4719296
Ref: option_mysqld_ndb_wait_connected4719544
Node: mysql-cluster-status-variables4720137
Ref: option_mysqld_Handler_discover4720639
Ref: option_mysqld_Ndb_cluster_node_id4720917
Ref: option_mysqld_Ndb_config_from_host4721161
Ref: option_mysqld_Ndb_config_from_port4721571
Ref: option_mysqld_Ndb_execute_count4721998
Ref: option_mysqld_Ndb_number_of_data_nodes4722145
Ref: option_mysqld_Slave_heartbeat_period4722487
Ref: option_mysqld_Slave_received_heartbeats4722666
Node: mysql-cluster-upgrade-downgrade4722960
Node: mysql-cluster-rolling-restart4724204
Node: mysql-cluster-upgrade-downgrade-compatibility4727228
Ref: mysql-cluster-upgrade-downgrade-compatibility-online-add-drop-column4731097
Ref: mysql-cluster-upgrade-downgrade-compatibility-online-add-drop-column-6-x4734412
Node: mysql-cluster-process-management4736289
Node: mysql-cluster-mysqld-process4737372
Node: mysql-cluster-ndbd-process4741631
Node: mysql-cluster-ndb-mgmd-process4747377
Node: mysql-cluster-ndb-mgm-process4749706
Node: mysql-cluster-command-options4750876
Node: mysql-cluster-ndbd-command-options4753517
Node: mysql-cluster-ndb-mgmd-command-options4758310
Node: mysql-cluster-ndb-mgm-command-options4760210
Node: mysql-cluster-management4760822
Node: mysql-cluster-start-phases4762877
Node: mysql-cluster-mgm-client-commands4769970
Node: mysql-cluster-event-reports4774552
Node: mysql-cluster-logging-management-commands4779623
Node: mysql-cluster-log-events4783028
Node: mysql-cluster-log-statistics4793783
Node: mysql-cluster-logs-ndb-messages4796503
Node: mysql-cluster-logs-cluster-log4797069
Node: mysql-cluster-ndb-transporter-errors4843046
Node: mysql-cluster-single-user-mode4849119
Node: mysql-cluster-sql-statements4851189
Node: mysql-cluster-security4858420
Node: mysql-cluster-security-networking-issues4859318
Node: mysql-cluster-security-mysql-privileges4869173
Node: mysql-cluster-security-mysql-security-procedures4876478
Node: mysql-cluster-backup4880416
Node: mysql-cluster-backup-concepts4881114
Node: mysql-cluster-backup-using-management-client4882948
Node: mysql-cluster-restore4889801
Node: mysql-cluster-backup-configuration4908098
Node: mysql-cluster-backup-troubleshooting4909222
Node: mysql-cluster-utilities4910739
Node: mysql-cluster-utilities-ndb-config4916759
Node: mysql-cluster-utilities-ndb-cpcd4922548
Node: mysql-cluster-utilities-ndb-delete-all4923231
Node: mysql-cluster-utilities-ndb-desc4924193
Node: mysql-cluster-utilities-ndb-drop-index4926368
Node: mysql-cluster-utilities-ndb-drop-table4928623
Node: mysql-cluster-utilities-ndb-error-reporter4929334
Node: mysql-cluster-utilities-ndb-print-backup-file4930877
Node: mysql-cluster-utilities-ndb-print-schema-file4932269
Node: mysql-cluster-utilities-ndb-print-sys-file4933486
Node: mysql-cluster-utilities-ndbd-redo-log-reader4934929
Node: mysql-cluster-utilities-ndb-select-all4937188
Node: mysql-cluster-utilities-ndb-select-count4941366
Node: mysql-cluster-utilities-ndb-show-tables4942403
Node: mysql-cluster-utilities-ndb-size4944106
Node: mysql-cluster-utilities-ndb-waiter4952451
Ref: mysql-cluster-utilities-ndb-waiter-additional-options4954047
Node: mysql-cluster-replication4956248
Node: mysql-cluster-replication-abbreviations4959374
Node: mysql-cluster-replication-general4960914
Node: mysql-cluster-replication-issues4963458
Node: mysql-cluster-replication-schema4975382
Node: mysql-cluster-replication-preparation4984617
Node: mysql-cluster-replication-starting4990251
Node: mysql-cluster-replication-two-channels4995024
Node: mysql-cluster-replication-failover4997755
Node: mysql-cluster-replication-backups5001165
Node: mysql-cluster-replication-auto-sync5009190
Node: mysql-cluster-replication-conflict-resolution5015198
Ref: option_mysqld_ndb_log_updated_only5018580
Ref: option_mysqld_ndb_log_update_as_write5019167
Ref: option_mysqld_Ndb_conflict_fn_max5024121
Ref: option_mysqld_Ndb_conflict_fn_old5024400
Node: mysql-cluster-disk-data5031063
Node: mysql-cluster-disk-data-objects5032174
Node: mysql-cluster-disk-data-storage-requirements5041654
Node: mysql-cluster-disk-data-parameters5042606
Ref: mysql-cluster-param-disk-data-diskpagebuffermemory5042924
Ref: mysql-cluster-param-disk-data-sharedglobalmemory5043288
Node: mysql-cluster-interconnects5043826
Node: mysql-cluster-sci-sockets5046273
Node: mysql-cluster-interconnects-performance5057345
Node: mysql-cluster-limitations5061245
Node: mysql-cluster-limitations-syntax5063543
Node: mysql-cluster-limitations-limits5067350
Node: mysql-cluster-limitations-transactions5071504
Node: mysql-cluster-limitations-error-handling5075734
Node: mysql-cluster-limitations-database-objects5076761
Node: mysql-cluster-limitations-unsupported-missing5078591
Node: mysql-cluster-limitations-performance5080238
Node: mysql-cluster-limitations-exclusive-to-cluster5081391
Node: mysql-cluster-limitations-disk-data5083394
Node: mysql-cluster-limitations-multiple-nodes5084698
Node: mysql-cluster-limitations-resolved5087743
Node: mysql-cluster-roadmap5094854
Node: mysql-cluster-changes-5-15101396
Ref: mysql-cluster-changes-5-1-distribution-awareness5105297
Node: mysql-cluster-changes-5-1-ndb-6-15107082
Node: mysql-cluster-changes-5-1-ndb-6-25108930
Node: mysql-cluster-changes-5-1-ndb-6-35114724
Node: mysql-cluster-glossary5124399
Node: mysql-cluster-news5137907
Node: mysql-cluster-news-6-35139268
Node: mysql-cluster-news-5-1-24-ndb-6-3-165141669
Node: mysql-cluster-news-5-1-24-ndb-6-3-155145373
Node: mysql-cluster-news-5-1-24-ndb-6-3-145150022
Node: mysql-cluster-news-5-1-24-ndb-6-3-135154488
Node: mysql-cluster-news-5-1-23-ndb-6-3-125162760
Node: mysql-cluster-news-5-1-23-ndb-6-3-115163541
Node: mysql-cluster-news-5-1-23-ndb-6-3-105164310
Node: mysql-cluster-news-5-1-23-ndb-6-3-95165929
Node: mysql-cluster-news-5-1-23-ndb-6-3-85170707
Node: mysql-cluster-news-5-1-23-ndb-6-3-75179015
Node: mysql-cluster-news-5-1-22-ndb-6-3-65183818
Node: mysql-cluster-news-5-1-22-ndb-6-3-55189015
Node: mysql-cluster-news-5-1-22-ndb-6-3-45190742
Node: mysql-cluster-news-5-1-22-ndb-6-3-35197618
Node: mysql-cluster-news-5-1-22-ndb-6-3-25200378
Node: mysql-cluster-news-5-1-19-ndb-6-3-15205711
Node: mysql-cluster-news-5-1-19-ndb-6-3-05207030
Node: mysql-cluster-news-6-25209834
Node: mysql-cluster-news-5-1-24-ndb-6-2-165212244
Node: mysql-cluster-news-5-1-23-ndb-6-2-155225095
Node: mysql-cluster-news-5-1-23-ndb-6-2-145225783
Node: mysql-cluster-news-5-1-23-ndb-6-2-135241426
Node: mysql-cluster-news-5-1-23-ndb-6-2-125242769
Node: mysql-cluster-news-5-1-23-ndb-6-2-115246943
Node: mysql-cluster-news-5-1-23-ndb-6-2-105251753
Node: mysql-cluster-news-5-1-22-ndb-6-2-95253995
Node: mysql-cluster-news-5-1-22-ndb-6-2-85257310
Node: mysql-cluster-news-5-1-22-ndb-6-2-75260951
Node: mysql-cluster-news-5-1-22-ndb-6-2-65264534
Node: mysql-cluster-news-5-1-22-ndb-6-2-55268030
Node: mysql-cluster-news-5-1-19-ndb-6-2-45274650
Node: mysql-cluster-news-5-1-19-ndb-6-2-35276616
Node: mysql-cluster-news-5-1-18-ndb-6-2-25278582
Node: mysql-cluster-news-5-1-18-ndb-6-2-15280504
Node: mysql-cluster-news-5-1-16-ndb-6-2-05282430
Node: mysql-cluster-news-6-15284682
Node: mysql-cluster-news-5-1-15-ndb-6-1-235287843
Node: mysql-cluster-news-5-1-15-ndb-6-1-225289386
Node: mysql-cluster-news-5-1-15-ndb-6-1-215290945
Node: mysql-cluster-news-5-1-15-ndb-6-1-205292418
Node: mysql-cluster-news-5-1-15-ndb-6-1-195293799
Node: mysql-cluster-news-5-1-15-ndb-6-1-185295303
Node: mysql-cluster-news-5-1-15-ndb-6-1-175297102
Node: mysql-cluster-news-5-1-15-ndb-6-1-165298564
Node: mysql-cluster-news-5-1-15-ndb-6-1-155300714
Node: mysql-cluster-news-5-1-15-ndb-6-1-145301999
Node: mysql-cluster-news-5-1-15-ndb-6-1-135303468
Node: mysql-cluster-news-5-1-15-ndb-6-1-125305048
Node: mysql-cluster-news-5-1-15-ndb-6-1-115306936
Node: mysql-cluster-news-5-1-15-ndb-6-1-105309257
Node: mysql-cluster-news-5-1-15-ndb-6-1-95312191
Node: mysql-cluster-news-5-1-15-ndb-6-1-85313689
Node: mysql-cluster-news-5-1-15-ndb-6-1-75315782
Node: mysql-cluster-news-5-1-15-ndb-6-1-65320984
Node: mysql-cluster-news-5-1-15-ndb-6-1-55325130
Node: mysql-cluster-news-5-1-15-ndb-6-1-45327580
Node: mysql-cluster-news-5-1-15-ndb-6-1-35330624
Node: mysql-cluster-news-5-1-15-ndb-6-1-25335132
Node: mysql-cluster-news-5-1-15-ndb-6-1-15336472
Node: mysql-cluster-news-5-1-14-ndb-6-1-05338538
Node: partitioning5342643
Node: partitioning-overview5346542
Node: partitioning-types5355878
Node: partitioning-range5361841
Node: partitioning-list5369553
Node: partitioning-hash5374910
Node: partitioning-linear-hash5381581
Node: partitioning-key5384480
Node: partitioning-subpartitions5388842
Node: partitioning-handling-nulls5397760
Node: partitioning-management5412286
Node: partitioning-management-range-list5416060
Node: partitioning-management-hash-key5432396
Node: partitioning-maintenance5435232
Node: partitioning-info5436815
Node: partitioning-pruning5442819
Node: partitioning-limitations5451027
Node: partitioning-limitations-partitioning-keys-unique-keys5464712
Node: partitioning-limitations-storage-engines5472987
Node: partitioning-limitations-functions5475241
Node: spatial-extensions5476824
Node: gis-introduction5478668
Node: opengis-geometry-model5480967
Node: gis-geometry-class-hierarchy5482241
Node: gis-class-geometry5484887
Node: gis-class-point5488444
Node: gis-class-curve5489071
Node: gis-class-linestring5489914
Node: gis-class-surface5490595
Node: gis-class-polygon5491313
Node: gis-class-geometrycollection5492534
Node: gis-class-multipoint5493361
Node: gis-class-multicurve5494130
Node: gis-class-multilinestring5495087
Node: gis-class-multisurface5495520
Node: gis-class-multipolygon5496097
Node: supported-spatial-data-formats5497566
Node: gis-wkt-format5498244
Node: gis-wkb-format5499712
Node: creating-a-spatially-enabled-mysql-database5501453
Node: mysql-spatial-datatypes5502188
Node: creating-spatial-values5503170
Node: gis-wkt-functions5503842
Ref: function_geomcollfromtext5504499
Ref: function_geomfromtext5504674
Ref: function_linefromtext5504830
Ref: function_mlinefromtext5504980
Ref: function_mpointfromtext5505141
Ref: function_mpolyfromtext5505293
Ref: function_pointfromtext5505448
Ref: function_polyfromtext5505555
Ref: function_bdmpolyfromtext5505977
Ref: function_bdpolyfromtext5506173
Node: gis-wkb-functions5506358
Ref: function_geomcollfromwkb5507041
Ref: function_geomfromwkb5507214
Ref: function_linefromwkb5507368
Ref: function_mlinefromwkb5507516
Ref: function_mpointfromwkb5507675
Ref: function_mpolyfromwkb5507825
Ref: function_pointfromwkb5507978
Ref: function_polyfromwkb5508084
Ref: function_bdmpolyfromwkb5508492
Ref: function_bdpolyfromwkb5508687
Node: gis-mysql-specific-functions5508871
Ref: function_geometrycollection5509552
Ref: function_linestring5509745
Ref: function_multilinestring5510022
Ref: function_multipoint5510222
Ref: function_multipolygon5510397
Ref: function_point5510597
Ref: function_polygon5510671
Node: creating-spatial-columns5510932
Node: populating-spatial-columns5511790
Node: fetching-spatial-data5514684
Node: analysing-spatial-information5515590
Node: functions-to-convert-geometries-between-formats5517250
Ref: function_asbinary5517656
Ref: function_astext5517843
Node: geometry-property-functions5518868
Node: general-geometry-property-functions5519955
Ref: function_dimension5520311
Ref: function_envelope5520885
Ref: function_geometrytype5521600
Ref: function_srid5522150
Ref: function_boundary5522895
Ref: function_isempty5523021
Ref: function_issimple5523231
Node: point-property-functions5523859
Ref: function_x5524186
Ref: function_y5524558
Node: linestring-property-functions5524925
Ref: function_endpoint5525328
Ref: function_glength5525798
Ref: function_numpoints5526354
Ref: function_pointn5526775
Ref: function_startpoint5527267
Ref: function_isring5527850
Node: multilinestring-property-functions5528126
Ref: function_isclosed5529066
Node: polygon-property-functions5529655
Ref: function_area5529948
Ref: function_exteriorring5530428
Ref: function_interiorringn5530990
Ref: function_numinteriorrings5531616
Node: multipolygon-property-functions5532141
Ref: function_centroid5533079
Node: geometrycollection-property-functions5533381
Ref: function_geometryn5533674
Ref: function_numgeometries5534228
Node: functions-that-create-new-geometries-from-existing-ones5534708
Node: functions-that-produce-new-geometries5535331
Node: spatial-operators5535999
Ref: function_buffer5536422
Ref: function_convexhull5536583
Ref: function_difference5536693
Ref: function_intersection5536825
Ref: function_symdifference5536962
Ref: function_union5537107
Node: functions-for-testing-spatial-relations-between-geometric-objects5537224
Node: relations-on-geometry-mbr5537747
Ref: function_mbrcontains5538303
Ref: function_mbrdisjoint5539010
Ref: function_mbrequal5539181
Ref: function_mbrintersects5539330
Ref: function_mbroverlaps5539481
Ref: function_mbrtouches5539825
Ref: function_mbrwithin5540173
Node: functions-that-test-spatial-relationships-between-geometries5540873
Ref: function_contains5541767
Ref: function_crosses5541917
Ref: function_disjoint5542544
Ref: function_distance5542670
Ref: function_equals5542811
Ref: function_intersects5542904
Ref: function_overlaps5543000
Ref: function_related5543289
Ref: function_touches5543605
Ref: function_within5543899
Node: optimizing-spatial-analysis5544044
Node: creating-spatial-indexes5545590
Node: using-a-spatial-index5547907
Node: mysql-gis-conformance-and-compatibility5554698
Node: stored-procedures5555693
Node: stored-procedure-privileges5559196
Node: stored-procedure-syntax5560886
Node: create-function5564246
Node: create-procedure5564735
Node: alter-procedure5578344
Node: drop-function5579268
Node: drop-procedure5579733
Node: call5580534
Node: begin-end5584423
Node: declare5585915
Node: variables-in-stored-procedures5586737
Node: declare-local-variables5587189
Node: set-statement5588086
Node: select-into-statement5588958
Node: conditions-and-handlers5590337
Node: declare-conditions5590799
Node: declare-handlers5591508
Node: cursors5596958
Node: declare-cursors5598553
Node: open5598946
Node: fetch5599176
Node: close5599717
Node: flow-control-constructs5600035
Node: if-statement5600979
Node: case-statement5603153
Node: loop-statement5605054
Node: leave-statement5605711
Node: iterate-statement5606065
Node: repeat-statement5606619
Node: while-statement5607724
Node: return5608452
Node: stored-procedure-last-insert-id5608962
Node: stored-procedure-logging5609996
Node: triggers5628662
Node: create-trigger5630166
Node: drop-trigger5638796
Node: using-triggers5639984
Node: events5648551
Node: events-overview5650120
Ref: events-event-scheduler-option5654325
Node: events-syntax5661241
Node: alter-event5662483
Node: create-event5667246
Node: drop-event5681621
Node: events-metadata5682431
Node: events-status-info5683029
Node: events-privileges5684617
Node: events-limitations-restrictions5693143
Node: views5698262
Node: alter-view5699348
Node: create-view5700215
Node: drop-view5721047
Node: information-schema5721816
Node: schemata-table5731174
Node: tables-table5732025
Node: columns-table5735656
Node: statistics-table5738047
Node: user-privileges-table5739935
Node: schema-privileges-table5740893
Node: table-privileges-table5741939
Node: column-privileges-table5743109
Node: character-sets-table5744720
Node: collations-table5745520
Node: collation-character-set-applicability-table5746507
Node: table-constraints-table5747193
Node: key-column-usage-table5748448
Node: routines-table5750975
Node: views-table5753709
Node: triggers-table5756351
Node: plugins-table5761797
Node: engines-table5763008
Node: partitions-table5763885
Node: events-table5772324
Node: files-table5783070
Node: processlist-table5797736
Node: referential-constraints-table5799575
Node: status-table5801344
Node: variables-table5802477
Node: other-information-schema-tables5803694
Node: extended-show5804082
Node: precision-math5810019
Node: precision-math-numbers5812587
Node: precision-math-decimal-changes5813980
Node: precision-math-expressions5817696
Node: precision-math-rounding5822351
Node: precision-math-examples5824291
Node: apis5832693
Node: libmysqld5833548
Node: libmysqld-compiling5836252
Node: libmysqld-restrictions5838523
Node: libmysqld-options5839668
Node: libmysqld-example5840960
Node: libmysqld-licensing5848109
Node: c5848577
Node: c-api-datatypes5852590
Node: c-api-function-overview5864450
Node: c-api-functions5883792
Node: mysql-affected-rows5891331
Node: mysql-autocommit5893985
Node: mysql-change-user5894436
Node: mysql-character-set-name5896884
Node: mysql-close5897352
Node: mysql-commit5897910
Node: mysql-connect5898643
Node: mysql-create-db5900130
Node: mysql-data-seek5901194
Node: mysql-debug5901990
Node: mysql-drop-db5902740
Node: mysql-dump-debug-info5903773
Node: mysql-eof5904602
Node: mysql-errno5907680
Node: mysql-error5909254
Node: mysql-escape-string5910594
Node: mysql-fetch-field5911342
Node: mysql-fetch-field-direct5913055
Node: mysql-fetch-fields5914129
Node: mysql-fetch-lengths5914984
Node: mysql-fetch-row5916761
Node: mysql-field-count5918933
Node: mysql-field-seek5921313
Node: mysql-field-tell5921971
Node: mysql-free-result5922546
Node: mysql-get-character-set-info5923282
Node: mysql-get-client-info5924564
Node: mysql-get-client-version5925064
Node: mysql-get-host-info5925796
Node: mysql-get-proto-info5926321
Node: mysql-get-server-info5926825
Node: mysql-get-server-version5927317
Node: mysql-get-ssl-cipher5928053
Node: mysql-hex-string5928737
Node: mysql-info5930709
Node: mysql-init5932195
Node: mysql-insert-id5933049
Node: mysql-kill5938316
Node: mysql-library-end5939141
Node: mysql-library-init5940201
Node: mysql-list-dbs5943393
Node: mysql-list-fields5944576
Node: mysql-list-processes5945895
Node: mysql-list-tables5946858
Node: mysql-more-results5948023
Node: mysql-next-result5949056
Node: mysql-num-fields5951854
Node: mysql-num-rows5954327
Node: mysql-options5955538
Node: mysql-ping5966721
Node: mysql-query5967739
Node: mysql-real-connect5969256
Node: mysql-real-escape-string5980350
Node: mysql-real-query5983303
Node: mysql-refresh5985071
Node: mysql-reload5986777
Node: mysql-rollback5987650
Node: mysql-row-seek5988402
Node: mysql-row-tell5989537
Node: mysql-select-db5990261
Node: mysql-set-character-set5991315
Node: mysql-set-local-infile-default5992588
Node: mysql-set-local-infile-handler5993459
Node: mysql-set-server-option5997487
Node: mysql-shutdown5999505
Node: mysql-sqlstate6000772
Node: mysql-ssl-set6002495
Node: mysql-stat6003828
Node: mysql-store-result6004699
Node: mysql-thread-id6008394
Node: mysql-use-result6009116
Node: mysql-warning-count6012674
Node: c-api-prepared-statements6013104
Node: c-api-prepared-statement-datatypes6016077
Node: c-api-prepared-statement-function-overview6037132
Node: c-api-prepared-statement-functions6047845
Node: mysql-stmt-affected-rows6050767
Node: mysql-stmt-attr-get6052468
Node: mysql-stmt-attr-set6053490
Node: mysql-stmt-bind-param6057217
Node: mysql-stmt-bind-result6058916
Node: mysql-stmt-close6061584
Node: mysql-stmt-data-seek6062521
Node: mysql-stmt-errno6063372
Node: mysql-stmt-error6064202
Node: mysql-stmt-execute6065297
Node: mysql-stmt-fetch6073135
Node: mysql-stmt-fetch-column6084564
Node: mysql-stmt-field-count6085920
Node: mysql-stmt-free-result6086747
Node: mysql-stmt-init6087416
Node: mysql-stmt-insert-id6088009
Node: mysql-stmt-num-rows6088928
Node: mysql-stmt-param-count6090137
Node: mysql-stmt-param-metadata6090833
Node: mysql-stmt-prepare6091275
Node: mysql-stmt-reset6093798
Node: mysql-stmt-result-metadata6094854
Node: mysql-stmt-row-seek6097091
Node: mysql-stmt-row-tell6098299
Node: mysql-stmt-send-long-data6099061
Node: mysql-stmt-sqlstate6102917
Node: mysql-stmt-store-result6103914
Node: c-api-prepared-statement-problems6106654
Node: c-api-multiple-queries6108007
Node: c-api-date-handling6115807
Node: c-thread-functions6119104
Node: my-init6119736
Node: mysql-thread-end6120852
Node: mysql-thread-init6121444
Node: mysql-thread-safe6122399
Node: c-embedded-server-func6122820
Node: mysql-server-init6123845
Node: mysql-server-end6124531
Node: auto-reconnect6125093
Node: c-api-problems6127239
Node: null-mysql-store-result6128170
Node: query-results6129743
Node: getting-unique-id6131385
Node: c-api-linking-problems6134526
Node: building-clients6135234
Node: threaded-clients6136818
Node: php6142785
Node: php-problems6145256
Node: php-mysql-mysqli6146852
Node: perl6148328
Node: cplusplus6150156
Node: python6150853
Node: tcl6151561
Node: eiffel6151828
Node: connectors6152140
Node: myodbc-connector6154280
Node: myodbc-versions6157707
Node: myodbc-introduction6160826
Node: connector-odbc-roadmap6161765
Node: myodbc-general-information6163656
Node: myodbc-architecture6164487
Node: myodbc-driver-manager6168265
Node: myodbc-installation6169961
Node: myodbc-installation-binary-windows6173272
Node: myodbc-installation-binary-windows-installer6175210
Node: myodbc-installation-binary-windows-dll6177421
Node: myodbc-installation-binary-unix6180401
Node: myodbc-installation-binary-unix-tarball6181159
Node: myodbc-installation-binary-unix-rpm6182352
Node: myodbc-installation-binary-macosx6183656
Node: myodbc-installation-source-windows6188155
Node: myodbc-installation-source-windows-3-51-building6189659
Node: myodbc-installation-source-windows-3-51-testing6191988
Node: myodbc-installation-source-unix6192443
Node: myodbc-installation-source-unix-configure-options6195252
Node: myodbc-installation-source-unix-otheroptions6197792
Node: myodbc-installation-source-unix-building6199882
Node: myodbc-installation-source-unix-shared-libraries6200429
Node: myodbc-installation-source-unix-installing6202943
Node: myodbc-installation-source-unix-testing6203909
Node: myodbc-installation-source-unix-macosx6204720
Node: myodbc-installation-source-unix-hpux6206661
Node: myodbc-installation-source-unix-aix6207987
Node: myodbc-installation-source-development6208770
Node: myodbc-configuration6211100
Node: myodbc-configuration-dsn6212464
Node: myodbc-configuration-connection-parameters6213860
Node: myodbc-configuration-dsn-windows6227175
Node: myodbc-configuration-dsn-windows-3-516230704
Node: myodbc-configuration-dsn-windows-5-16234130
Node: myodbc-configuration-dsn-windows-problems6237537
Node: myodbc-configuration-dsn-macosx6238854
Node: myodbc-configuration-dsn-unix6241664
Node: myodbc-configuration-connection-without-dsn6243601
Node: myodbc-configuration-connection-pooling6245084
Node: myodbc-configuration-trace6245823
Node: myodbc-configuration-trace-windows6246594
Node: myodbc-configuration-trace-macosx6247638
Node: myodbc-configuration-trace-unix6248337
Node: myodbc-configuration-trace-log6249344
Node: myodbc-examples6250402
Node: myodbc-examples-overview6251477
Node: myodbc-examples-walkthrough6252203
Node: myodbc-examples-tools6254302
Node: myodbc-examples-tools-with-access6256828
Node: myodbc-examples-tools-with-access-export6257635
Node: myodbc-examples-tools-with-access-import6259426
Node: myodbc-examples-tools-with-access-linked-tables6260642
Node: myodbc-examples-tools-with-wordexcel6264094
Node: myodbc-examples-tools-with-crystalreports6267263
Node: myodbc-examples-programming6271962
Node: myodbc-examples-programming-vb6272741
Node: myodbc-examples-programming-vb-ado6273410
Node: myodbc-examples-programming-vb-dao6276305
Node: myodbc-examples-programming-vb-rdo6278702
Node: myodbc-examples-programming-net6280864
Node: myodbc-examples-programming-net-csharp6281384
Node: myodbc-examples-programming-net-vb6287300
Node: myodbc-reference6291259
Node: myodbc-reference-api6291895
Node: myodbc-reference-datatypes6303408
Node: myodbc-reference-errorcodes6306358
Node: myodbc-usagenotes6309570
Node: myodbc-usagenotes-functionality6310208
Node: myodbc-usagenotes-functionality-last-insert-id6310905
Node: myodbc-usagenotes-functionality-dynamic-cursor6312265
Node: myodbc-usagenotes-functionality-performance6312921
Node: myodbc-usagenotes-functionality-query-timeout6314476
Node: myodbc-usagenotes-apptips6314977
Node: myodbc-usagenotes-apptips-microsoft6316395
Node: myodbc-usagenotes-apptips-microsoft-access6317549
Node: myodbc-usagenotes-apptips-microsoft-excel6322080
Node: myodbc-usagenotes-apptips-microsoft-visualbasic6323259
Node: myodbc-usagenotes-apptips-microsoft-visualinterdev6324255
Node: myodbc-usagenotes-apptips-microsoft-visualobjects6324795
Node: myodbc-usagenotes-apptips-microsoft-ado6325136
Node: myodbc-usagenotes-apptips-microsoft-asp6326705
Node: myodbc-usagenotes-apptips-microsoft-vb-asp6327592
Node: myodbc-usagenotes-apptips-borland6328302
Node: myodbc-usagenotes-apptips-borland-builder6329155
Node: myodbc-usagenotes-apptips-borland-delphi6329682
Node: myodbc-usagenotes-apptips-borland-cppbuilder6331639
Node: myodbc-usagenotes-apptips-coldfusion6332138
Node: myodbc-usagenotes-apptips-openoffice6333524
Node: myodbc-usagenotes-apptips-sambarserver6334037
Node: myodbc-usagenotes-apptips-datajunction6334467
Node: myodbc-usagenotes-apptips-vision6334920
Node: myodbc-errors6335224
Ref: qandaitem-31-1-7-3-16339225
Ref: qandaitem-31-1-7-3-26340217
Ref: qandaitem-31-1-7-3-36340566
Ref: qandaitem-31-1-7-3-46341327
Ref: qandaitem-31-1-7-3-56343256
Ref: qandaitem-31-1-7-3-66343654
Ref: qandaitem-31-1-7-3-76343912
Ref: qandaitem-31-1-7-3-86344178
Ref: qandaitem-31-1-7-3-96344441
Ref: qandaitem-31-1-7-3-106344741
Ref: qandaitem-31-1-7-3-116345205
Ref: qandaitem-31-1-7-3-126345919
Ref: qandaitem-31-1-7-3-136346226
Ref: qandaitem-31-1-7-3-146346567
Ref: qandaitem-31-1-7-3-156346966
Ref: qandaitem-31-1-7-3-166347377
Ref: qandaitem-31-1-7-3-176347926
Ref: qandaitem-31-1-7-3-186348277
Ref: qandaitem-31-1-7-3-196348677
Ref: qandaitem-31-1-7-3-206349234
Ref: qandaitem-31-1-7-3-216349642
Ref: qandaitem-31-1-7-3-226350197
Node: myodbc-support6350481
Node: myodbc-support-community6351231
Node: myodbc-support-bug-report6352117
Node: myodbc-support-patch-submission6354574
Node: myodbc-support-changehistory6354960
Node: myodbc-support-credits6355307
Node: connector-net6355634
Node: connector-net-versions6358135
Node: connector-net-installation6359581
Node: connector-net-installation-windows6360393
Node: connector-net-installation-binary-windows-installer6361147
Node: connector-net-installation-binary-windows-zip6365515
Node: connector-net-installation-unix6366539
Node: connector-net-installation-source6368053
Node: connector-net-examples6369138
Node: connector-net-examples-mysqlcommand6371242
Node: connector-net-examples-mysqlcommand-ctor16376377
Node: connector-net-examples-mysqlcommand-ctor26379534
Node: connector-net-examples-mysqlcommand-ctor36380951
Node: connector-net-examples-mysqlcommand-ctor46382636
Node: connector-net-examples-mysqlcommand-executenonquery6384598
Node: connector-net-examples-mysqlcommand-executereader16386329
Node: connector-net-examples-mysqlcommand-executereader6388129
Node: connector-net-examples-mysqlcommand-prepare6390350
Node: connector-net-examples-mysqlcommand-executescalar6391662
Node: connector-net-examples-mysqlcommand-commandtext6393883
Node: connector-net-examples-mysqlcommand-commandtimeout6395236
Node: connector-net-examples-mysqlcommand-commandtype6396321
Node: connector-net-examples-mysqlcommand-connection6397421
Node: connector-net-examples-mysqlcommand-isprepared6399108
Node: connector-net-examples-mysqlcommand-parameters6399423
Node: connector-net-examples-mysqlcommand-transaction6401728
Node: connector-net-examples-mysqlcommand-updatedrowsource6402548
Node: connector-net-examples-mysqlcommandbuilder6403191
Node: connector-net-examples-mysqlcommandbuilder-ctor6409285
Node: connector-net-examples-mysqlcommandbuilder-ctor16409680
Node: connector-net-examples-mysqlcommandbuilder-ctor26410687
Node: connector-net-examples-mysqlcommandbuilder-ctor36411511
Node: connector-net-examples-mysqlcommandbuilder-dataadapter6412897
Node: connector-net-examples-mysqlcommandbuilder-quoteprefix6413646
Node: connector-net-examples-mysqlcommandbuilder-quotesuffix6414509
Node: connector-net-examples-mysqlcommandbuilder-deriveparameters6415377
Node: connector-net-examples-mysqlcommandbuilder-getdeletecommand6415701
Node: connector-net-examples-mysqlcommandbuilder-getinsertcommand6416999
Node: connector-net-examples-mysqlcommandbuilder-getupdatecommand6418302
Node: connector-net-examples-mysqlcommandbuilder-refreshschema6419595
Node: connector-net-examples-mysqlconnection6420542
Node: connector-net-examples-mysqlconnection-defctor6424220
Node: connector-net-examples-mysqlconnection-ctor16425367
Node: connector-net-examples-mysqlconnection-connectionstring6426552
Node: connector-net-examples-mysqlconnection-open6445945
Node: connector-net-examples-mysqlconnection-database6447482
Node: connector-net-examples-mysqlconnection-state6449679
Node: connector-net-examples-mysqlconnection-serverversion6451184
Node: connector-net-examples-mysqlconnection-close6452501
Node: connector-net-examples-mysqlconnection-createcommand6453982
Node: connector-net-examples-mysqlconnection-begintransaction6454396
Node: connector-net-examples-mysqlconnection-begintransaction16458825
Node: connector-net-examples-mysqlconnection-changedatabase6463365
Node: connector-net-examples-mysqlconnection-statechange6466154
Node: connector-net-examples-mysqlconnection-infomessage6467621
Node: connector-net-examples-mysqlconnection-connectiontimeout6467996
Node: connector-net-examples-mysqldataadapter6469292
Node: connector-net-examples-mysqldataadapter-ctor6473300
Node: connector-net-examples-mysqldataadapter-ctor16476993
Node: connector-net-examples-mysqldataadapter-ctor26481124
Node: connector-net-examples-mysqldataadapter-ctor36485350
Node: connector-net-examples-mysqldataadapter-deletecommand6489161
Node: connector-net-examples-mysqldataadapter-insertcommand6492122
Node: connector-net-examples-mysqldataadapter-updatecommand6495344
Node: connector-net-examples-mysqldataadapter-selectcommand6498819
Node: connector-net-examples-mysqldatareader6501447
Node: connector-net-examples-mysqldatareader-getbytes6505614
Node: connector-net-examples-mysqldatareader-gettimespan6506562
Node: connector-net-examples-mysqldatareader-getdatetime6507004
Node: connector-net-examples-mysqldatareader-getmysqldatetime6507977
Node: connector-net-examples-mysqldatareader-getstring6508457
Node: connector-net-examples-mysqldatareader-getdecimal6508898
Node: connector-net-examples-mysqldatareader-getdouble6509335
Node: connector-net-examples-mysqldatareader-getfloat6509791
Node: connector-net-examples-mysqldatareader-getgiud6510242
Node: connector-net-examples-mysqldatareader-getint166510685
Node: connector-net-examples-mysqldatareader-getint326511118
Node: connector-net-examples-mysqldatareader-getint646511552
Node: connector-net-examples-mysqldatareader-getuint166511987
Node: connector-net-examples-mysqldatareader-getuint326512427
Node: connector-net-examples-mysqldatareader-getuint646512868
Node: connector-net-examples-mysqlexception6513252
Node: connector-net-examples-mysqlparameter6514891
Node: connector-net-examples-mysqlparametercollection6516394
Node: connector-net-examples-mysqltransaction6518036
Node: connector-net-examples-mysqltransaction-rollback6522902
Node: connector-net-examples-mysqltransaction-commit6526978
Node: connector-net-ref6530859
Node: connector-net-ref-mysqlclient6531325
Node: connector-net-ref-mysqlclienthierarchy6536450
Node: connector-net-ref-mysqlclient-mysqlcommand6536814
Node: connector-net-ref-mysqlclient-mysqlcommandmembers6537997
Node: connector-net-ref-mysqlclient-mysqlcommandconstructor6543723
Node: connector-net-ref-mysqlclient-mysqlcommandconstructor16545250
Node: connector-net-ref-mysqlclient-mysqlcommandconstructor26546062
Node: connector-net-ref-mysqlclient-mysqlcommandconstructor36546847
Node: connector-net-ref-mysqlclient-mysqlconnection6547778
Node: connector-net-ref-mysqlclient-mysqlconnectionmembers6548983
Node: connector-net-ref-mysqlclient-mysqlconnectionconstructor6555195
Node: connector-net-ref-mysqlclient-mysqlconnectionconstructor16556365
Node: connector-net-ref-mysqlclient-mysqlconnectionconstructor26557212
Node: connector-net-ref-mysqlclient-mysqlconnection-connectionstring6557966
Node: connector-net-ref-mysqlclient-mysqlconnection-connectiontimeout6558743
Node: connector-net-ref-mysqlclient-mysqlconnection-database6559526
Node: connector-net-ref-mysqlclient-mysqlconnection-datasource6560251
Node: connector-net-ref-mysqlclient-mysqlconnection-serverthread6560932
Node: connector-net-ref-mysqlclient-mysqlconnection-serverversion6561637
Node: connector-net-ref-mysqlclient-mysqlconnection-state6562274
Node: connector-net-ref-mysqlclient-mysqlconnection-usecompression6563008
Node: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overloads6563752
Node: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-16564838
Node: connector-net-ref-mysqlclient-mysqltransaction6565824
Node: connector-net-ref-mysqlclient-mysqltransactionmembers6567044
Node: connector-net-ref-mysqlclient-mysqltransaction-connection6569516
Node: connector-net-ref-mysqlclient-mysqltransaction-isolationlevel6570829
Node: connector-net-ref-mysqlclient-mysqltransaction-commit6571882
Node: connector-net-ref-mysqlclient-mysqltransaction-rollback6572602
Node: connector-net-ref-mysqlclient-mysqlconnection-begintransaction-overload-26573264
Node: connector-net-ref-mysqlclient-mysqlconnection-changedatabase6574157
Node: connector-net-ref-mysqlclient-mysqlconnection-close6575009
Node: connector-net-ref-mysqlclient-mysqlconnection-createcommand6575717
Node: connector-net-ref-mysqlclient-mysqlconnection-open6576379
Node: connector-net-ref-mysqlclient-mysqlconnection-ping6577070
Node: connector-net-ref-mysqlclient-mysqlconnection-infomessage6577702
Node: connector-net-ref-mysqlclient-mysqlinfomessageeventhandler6578503
Node: connector-net-ref-mysqlclient-mysqlinfomessageeventargs6579653
Node: connector-net-ref-mysqlclient-mysqlinfomessageeventargsmembers6580956
Node: connector-net-ref-mysqlclient-mysqlinfomessageeventargsconstructor6583458
Node: connector-net-ref-mysqlclient-mysqlinfomessageeventargs-errors6584283
Node: connector-net-ref-mysqlclient-mysqlerror6584986
Node: connector-net-ref-mysqlclient-mysqlerrormembers6586083
Node: connector-net-ref-mysqlclient-mysqlerrorconstructor6588491
Node: connector-net-ref-mysqlclient-mysqlerror-code6589271
Node: connector-net-ref-mysqlclient-mysqlerror-level6589841
Node: connector-net-ref-mysqlclient-mysqlerror-message6590415
Node: connector-net-ref-mysqlclient-mysqlconnection-statechange6590945
Node: connector-net-ref-mysqlclient-mysqlcommandconstructor46591563
Node: connector-net-ref-mysqlclient-mysqlcommand-commandtext6592431
Node: connector-net-ref-mysqlclient-mysqlcommand-commandtimeout6593146
Node: connector-net-ref-mysqlclient-mysqlcommand-commandtype6593878
Node: connector-net-ref-mysqlclient-mysqlcommand-connection6594615
Node: connector-net-ref-mysqlclient-mysqlcommand-isprepared6595237
Node: connector-net-ref-mysqlclient-mysqlcommand-parameters6595843
Node: connector-net-ref-mysqlclient-mysqlparametercollection6596590
Node: connector-net-ref-mysqlclient-mysqlparametercollectionmembers6598188
Node: connector-net-ref-mysqlclient-mysqlparametercollectionconstructor6604528
Node: connector-net-ref-mysqlclient-mysqlparametercollection-count6605341
Node: connector-net-ref-mysqlclient-mysqlparametercollectionitem6606141
Node: connector-net-ref-mysqlclient-mysqlparameter6607653
Node: connector-net-ref-mysqlclient-mysqlparametermembers6609157
Node: connector-net-ref-mysqlclient-mysqlparameterconstructor6615472
Node: connector-net-ref-mysqlclient-mysqlparameterconstructor16618582
Node: connector-net-ref-mysqlclient-mysqlparameterconstructor36619368
Node: connector-net-ref-mysqlclient-mysqldbtype6620644
Node: connector-net-ref-mysqlclient-mysqlparameterconstructor46626972
Node: connector-net-ref-mysqlclient-mysqlparameterconstructor66628376
Node: connector-net-ref-mysqlclient-mysqlparameter-value6631183
Node: connector-net-ref-mysqlclient-mysqlparameterconstructor56631856
Node: connector-net-ref-mysqlclient-mysqlparameterconstructor26633344
Node: connector-net-ref-mysqlclient-mysqlparameter-dbtype6634500
Node: connector-net-ref-mysqlclient-mysqlparameter-direction6635249
Node: connector-net-ref-mysqlclient-mysqlparameter-isnullable6636216
Node: connector-net-ref-mysqlclient-mysqlparameter-isunsigned6637014
Node: connector-net-ref-mysqlclient-mysqlparameter-mysqldbtype6637629
Node: connector-net-ref-mysqlclient-mysqlparameter-parametername6638314
Node: connector-net-ref-mysqlclient-mysqlparameter-precision6639105
Node: connector-net-ref-mysqlclient-mysqlparameter-scale6639961
Node: connector-net-ref-mysqlclient-mysqlparameter-size6640774
Node: connector-net-ref-mysqlclient-mysqlparameter-sourcecolumn6641528
Node: connector-net-ref-mysqlclient-mysqlparameter-sourceversion6642440
Node: connector-net-ref-mysqlclient-mysqlparameter-tostring6643331
Node: connector-net-ref-mysqlclient-mysqlparametercollection-item16644057
Node: connector-net-ref-mysqlclient-mysqlparametercollection-item26645004
Node: connector-net-ref-mysqlclient-mysqlparametercollection-add-overloads6645901
Node: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-26649430
Node: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-16650804
Node: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-46652227
Node: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-56653719
Node: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-66655317
Node: connector-net-ref-mysqlclient-mysqlparametercollection-add-overload-36657057
Node: connector-net-ref-mysqlclient-mysqlparametercollection-clear6658560
Node: connector-net-ref-mysqlclient-mysqlparametercollection-contains-overloads6659368
Node: connector-net-ref-mysqlclient-mysqlparametercollection-contains-overload-16660801
Node: connector-net-ref-mysqlclient-mysqlparametercollection-contains-overload-26662199
Node: connector-net-ref-mysqlclient-mysqlparametercollection-copyto6663571
Node: connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overloads6664605
Node: connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overload-16666025
Node: connector-net-ref-mysqlclient-mysqlparametercollection-indexof-overload-26667423
Node: connector-net-ref-mysqlclient-mysqlparametercollection-insert6668851
Node: connector-net-ref-mysqlclient-mysqlparametercollection-remove6669846
Node: connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overloads6670767
Node: connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overload-16672147
Node: connector-net-ref-mysqlclient-mysqlparametercollection-removeat-overload-26673373
Node: connector-net-ref-mysqlclient-mysqlcommand-transaction6674627
Node: connector-net-ref-mysqlclient-mysqlcommand-updatedrowsource6675263
Node: connector-net-ref-mysqlclient-mysqlcommand-cancel6676038
Node: connector-net-ref-mysqlclient-mysqlcommand-createparameter6677045
Node: connector-net-ref-mysqlclient-mysqlcommand-executenonquery6677984
Node: connector-net-ref-mysqlclient-mysqlcommand-executereader-overloads6678760
Node: connector-net-ref-mysqlclient-mysqlcommand-executereader-overload-16679778
Node: connector-net-ref-mysqlclient-mysqldatareader6680702
Node: connector-net-ref-mysqlclient-mysqldatareadermembers6682119
Node: connector-net-ref-mysqlclient-mysqldatareader-depth6692979
Node: connector-net-ref-mysqlclient-mysqldatareader-fieldcount6693796
Node: connector-net-ref-mysqlclient-mysqldatareader-hasrows6694564
Node: connector-net-ref-mysqlclient-mysqldatareader-isclosed6695253
Node: connector-net-ref-mysqlclient-mysqldatareaderitem6696018
Node: connector-net-ref-mysqlclient-mysqldatareader-item16697270
Node: connector-net-ref-mysqlclient-mysqldatareader-item26698302
Node: connector-net-ref-mysqlclient-mysqldatareader-recordsaffected6699275
Node: connector-net-ref-mysqlclient-mysqldatareader-close6700116
Node: connector-net-ref-mysqlclient-mysqldatareader-getboolean6700856
Node: connector-net-ref-mysqlclient-mysqldatareader-getbyte6701746
Node: connector-net-ref-mysqlclient-mysqldatareader-getbytes6702615
Node: connector-net-ref-mysqlclient-mysqldatareader-getchar6704130
Node: connector-net-ref-mysqlclient-mysqldatareader-getchars6705009
Node: connector-net-ref-mysqlclient-mysqldatareader-getdatatypename6706267
Node: connector-net-ref-mysqlclient-mysqldatareader-getdatetime6707186
Node: connector-net-ref-mysqlclient-mysqldatareader-getdecimal6708010
Node: connector-net-ref-mysqlclient-mysqldatareader-getdouble6708824
Node: connector-net-ref-mysqlclient-mysqldatareader-getfieldtype6709631
Node: connector-net-ref-mysqlclient-mysqldatareader-getfloat6710535
Node: connector-net-ref-mysqlclient-mysqldatareader-getguid6711331
Node: connector-net-ref-mysqlclient-mysqldatareader-getint166712114
Node: connector-net-ref-mysqlclient-mysqldatareader-getint326712905
Node: connector-net-ref-mysqlclient-mysqldatareader-getint646713697
Node: connector-net-ref-mysqlclient-mysqldatareader-getmysqldatetime6714495
Node: connector-net-ref-mysqlclient-mysqldatareader-getname6715243
Node: connector-net-ref-mysqlclient-mysqldatareader-getordinal6716113
Node: connector-net-ref-mysqlclient-mysqldatareader-getschematable6717024
Node: connector-net-ref-mysqlclient-mysqldatareader-getstring6717904
Node: connector-net-ref-mysqlclient-mysqldatareader-gettimespan6718714
Node: connector-net-ref-mysqlclient-mysqldatareader-getuint166719430
Node: connector-net-ref-mysqlclient-mysqldatareader-getuint326720134
Node: connector-net-ref-mysqlclient-mysqldatareader-getuint646720834
Node: connector-net-ref-mysqlclient-mysqldatareader-getvalue6721534
Node: connector-net-ref-mysqlclient-mysqldatareader-getvalues6722425
Node: connector-net-ref-mysqlclient-mysqldatareader-isdbnull6723345
Node: connector-net-ref-mysqlclient-mysqldatareader-nextresult6724259
Node: connector-net-ref-mysqlclient-mysqldatareader-read6725113
Node: connector-net-ref-mysqlclient-mysqlcommand-executereader-overload-26725822
Node: connector-net-ref-mysqlclient-mysqlcommand-executescalar6726673
Node: connector-net-ref-mysqlclient-mysqlcommand-prepare6727429
Node: connector-net-ref-mysqlclient-mysqlcommandbuilder6728057
Node: connector-net-ref-mysqlclient-mysqlcommandbuildermembers6729252
Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overloads6734483
Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overload-16736129
Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-deriveparameters-overload-26737811
Node: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor6738777
Node: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor16740504
Node: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor36741405
Node: connector-net-ref-mysqlclient-mysqldataadapter6742360
Node: connector-net-ref-mysqlclient-mysqldataadaptermembers6743528
Node: connector-net-ref-mysqlclient-mysqldataadapterconstructor6752229
Node: connector-net-ref-mysqlclient-mysqldataadapterconstructor16753862
Node: connector-net-ref-mysqlclient-mysqldataadapterconstructor26754724
Node: connector-net-ref-mysqlclient-mysqldataadapterconstructor36755563
Node: connector-net-ref-mysqlclient-mysqldataadapterconstructor46756477
Node: connector-net-ref-mysqlclient-mysqldataadapter-deletecommand16757318
Node: connector-net-ref-mysqlclient-mysqldataadapter-insertcommand16757993
Node: connector-net-ref-mysqlclient-mysqldataadapter-selectcommand16758672
Node: connector-net-ref-mysqlclient-mysqldataadapter-updatecommand16759351
Node: connector-net-ref-mysqlclient-mysqldataadapter-rowupdated6760026
Node: connector-net-ref-mysqlclient-mysqlrowupdatedeventhandler6762475
Node: connector-net-ref-mysqlclient-mysqlrowupdatedeventargs6763545
Node: connector-net-ref-mysqlclient-mysqlrowupdatedeventargsmembers6764878
Node: connector-net-ref-mysqlclient-mysqlrowupdatedeventargsconstructor6768126
Node: connector-net-ref-mysqlclient-mysqlrowupdatedeventargs-command16769462
Node: connector-net-ref-mysqlclient-mysqldataadapter-rowupdating6770144
Node: connector-net-ref-mysqlclient-mysqlrowupdatingeventhandler6772310
Node: connector-net-ref-mysqlclient-mysqlrowupdatingeventargs6773392
Node: connector-net-ref-mysqlclient-mysqlrowupdatingeventargsmembers6774741
Node: connector-net-ref-mysqlclient-mysqlrowupdatingeventargsconstructor6777591
Node: connector-net-ref-mysqlclient-mysqlrowupdatingeventargs-command16778919
Node: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor46779609
Node: connector-net-ref-mysqlclient-mysqlcommandbuilderconstructor26780539
Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-dataadapter6781324
Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-quoteprefix6781997
Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-quotesuffix6782651
Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-getdeletecommand6783310
Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-getinsertcommand6784039
Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-getupdatecommand6784773
Node: connector-net-ref-mysqlclient-mysqlcommandbuilder-refreshschema6785504
Node: connector-net-ref-mysqlclient-mysqlexception6786119
Node: connector-net-ref-mysqlclient-mysqlexceptionmembers6787366
Node: connector-net-ref-mysqlclient-mysqlexception-number6790622
Node: connector-net-ref-mysqlclient-mysqlhelper6791203
Node: connector-net-ref-mysqlclient-mysqlhelpermembers6792337
Node: connector-net-ref-mysqlclient-mysqlhelper-executedatarow6795936
Node: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overloads6797224
Node: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-36799737
Node: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-46801159
Node: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-16802753
Node: connector-net-ref-mysqlclient-mysqlhelper-executedataset-overload-26804060
Node: connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overloads6805462
Node: connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overload-16807206
Node: connector-net-ref-mysqlclient-mysqlhelper-executenonquery-overload-26808872
Node: connector-net-ref-mysqlclient-mysqlhelper-executereader-overloads6810467
Node: connector-net-ref-mysqlclient-mysqlhelper-executereader-overload-16811677
Node: connector-net-ref-mysqlclient-mysqlhelper-executereader-overload-26812970
Node: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overloads6814446
Node: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-36816233
Node: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-46817563
Node: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-16819065
Node: connector-net-ref-mysqlclient-mysqlhelper-executescalar-overload-26820336
Node: connector-net-ref-mysqlclient-mysqlhelper-updatedataset6821705
Node: connector-net-ref-mysqlclient-mysqlerrorcode6822843
Node: connector-net-ref-types6823808
Node: connector-net-ref-typeshierarchy6824663
Node: connector-net-ref-types-mysqlconversionexception6824995
Node: connector-net-ref-types-mysqlconversionexceptionmembers6826225
Node: connector-net-ref-types-mysqlconversionexceptionconstructor6830263
Node: connector-net-ref-types-mysqldatetime6830901
Node: connector-net-ref-types-mysqldatetimemembers6832023
Node: connector-net-ref-types-mysqldatetime-op-explicit6837005
Node: connector-net-ref-types-mysqldatetime-day6837728
Node: connector-net-ref-types-mysqldatetime-hour6838297
Node: connector-net-ref-types-mysqlvalue-isnull6838863
Node: connector-net-ref-types-mysqlvalue6839470
Node: connector-net-ref-types-mysqlvaluemembers6840438
Node: connector-net-ref-types-mysqlvalue-numberformat6844139
Node: connector-net-ref-types-mysqlvalueconstructor6844736
Node: connector-net-ref-types-mysqlvalue-valueasobject6845363
Node: connector-net-ref-types-mysqlvalue-tostring6845977
Node: connector-net-ref-types-mysqlvalue-classtype6846601
Node: connector-net-ref-types-mysqlvalue-dbtype6847186
Node: connector-net-ref-types-mysqlvalue-mysqldbtype6847757
Node: connector-net-ref-types-mysqlvalue-mysqltypename6848356
Node: connector-net-ref-types-mysqlvalue-objectvalue6848973
Node: connector-net-ref-types-mysqldatetime-isvaliddatetime6849484
Node: connector-net-ref-types-mysqldatetime-minute6850151
Node: connector-net-ref-types-mysqldatetime-month6850743
Node: connector-net-ref-types-mysqldatetime-second6851321
Node: connector-net-ref-types-mysqldatetime-year6851902
Node: connector-net-ref-types-mysqldatetime-getdatetime6852479
Node: connector-net-ref-types-mysqldatetime-tostring6853100
Node: connector-net-using6853705
Node: connector-net-using-connecting6854632
Node: connector-net-using-connecting-introduction6855169
Node: connector-net-using-connecting-connection-string6855851
Node: connector-net-using-connecting-open6857591
Node: connector-net-using-connecting-errors6860060
Node: connector-net-using-prepared6862754
Node: connector-net-using-prepared-introduction6863181
Node: connector-net-using-prepared-preparing6864160
Node: connector-net-using-stored6866749
Node: connector-net-using-stored-introduction6867255
Node: connector-net-using-stored-creating6869384
Node: connector-net-using-stored-calling6871956
Node: connector-net-using-blob6875526
Node: connector-net-using-blob-introduction6876066
Node: connector-net-using-blob-serverprep6876805
Node: connector-net-using-blob-writing6878937
Node: connector-net-using-blob-reading6882388
Node: connector-net-using-crystal6886178
Node: connector-net-using-crystal-introduction6886694
Node: connector-net-using-crystal-source6887132
Node: connector-net-using-crystal-creating6890618
Node: connector-net-using-crystal-displaying6891699
Node: connector-net-using-datetime6899330
Node: connector-net-using-datetime-introduction6899950
Node: connector-net-using-datetime-problems6900543
Node: connector-net-using-datetime-restricting6901229
Node: connector-net-using-datetime-invalid6902255
Node: connector-net-using-datetime-null6903976
Node: connector-net-using-faq6905000
Ref: qandaitem-31-2-5-7-16905390
Node: connect-net-support6906984
Node: connector-net-support-community6907652
Node: connector-net-support-bug-report6908244
Node: connector-net-support-changehistory6909348
Node: connector-vstudio6909681
Node: connector-vstudio-install6910932
Node: connector-vstudio-creating6916516
Node: connector-vstudio-using6919225
Node: connector-vstudio-using-tables6920826
Node: connector-vstudio-using-tables-columns6922650
Node: connector-vstudio-using-tables-indexes6924049
Node: connector-vstudio-using-tables-foreignkeys6924997
Node: connector-vstudio-using-tables-column6926448
Node: connector-vstudio-using-tables-properties6926965
Node: connector-vstudio-using-tabledata6927950
Node: connector-vstudio-using-views6929280
Node: connector-vstudio-using-storedroutines6930695
Node: connector-vstudio-using-triggers6932671
Node: connector-vstudio-using-udf6934177
Node: connector-vstudio-using-dropping6935316
Node: connector-vstudio-using-cloning6935903
Node: connector-vstudio-support6936646
Node: connector-vstudio-faq6937080
Ref: qandaitem-31-3-4-1-16937434
Node: connector-j6937851
Node: connector-j-versions6940830
Node: connector-j-versions-java6943327
Node: connector-j-installing6945141
Node: connector-j-installing-binary6946141
Node: connector-j-installing-classpath6948031
Node: connector-j-installing-upgrading6951002
Node: connector-j-installing-upgrading-3-0-to-3-16951997
Node: connector-j-installing-upgrading-5-16956946
Node: connector-j-installing-upgrading-issues6958242
Node: connector-j-installing-source6959662
Node: connector-j-examples6963712
Node: connector-j-reference6964700
Node: connector-j-reference-configuration-properties6965686
Node: connector-j-reference-implementation-notes7034382
Node: connector-j-reference-type-conversions7044706
Node: connector-j-reference-charsets7050307
Node: connector-j-reference-using-ssl7053831
Node: connector-j-reference-replication-connection7062319
Node: connector-j-reference-error-sqlstates7066246
Node: connector-j-usagenotes7075625
Node: connector-j-usagenotes-basic7076047
Node: connector-j-usagenotes-connect-drivermanager7076689
Ref: connector-j-examples-connection-drivermanager7078474
Node: connector-j-usagenotes-statements7079564
Ref: connector-j-examples-execute-select7081063
Node: connector-j-usagenotes-statements-callable7082094
Ref: connector-j-examples-stored-procedure7083244
Ref: connector-j-examples-preparecall7083846
Ref: connector-j-examples-output-param7084943
Ref: connector-j-examples-callablestatement7086235
Ref: connector-j-examples-retrieving-results-params7087257
Node: connector-j-usagenotes-last-insert-id7087980
Ref: connector-j-examples-autoincrement-getgeneratedkeys7089347
Ref: connector-j-examples-autoincrement-select7091380
Ref: connector-j-examples-autoincrement-updateable-resultsets7093188
Node: connector-j-usagenotes-j2ee7095743
Node: connector-j-usagenotes-j2ee-concepts7096460
Node: connector-j-usagenotes-j2ee-concepts-connection-pooling7096896
Ref: connector-j-examples-connectionpool-j2ee7100331
Node: connector-j-usagenotes-tomcat7105375
Node: connector-j-usagenotes-jboss7110855
Node: connector-j-usagenotes-spring-config7113266
Node: connector-j-usagenotes-spring-config-jdbctemplate7118480
Node: connector-j-usagenotes-spring-config-transactional7122023
Node: connector-j-usagenotes-spring-config-connpooling7126614
Node: connector-j-usagenotes-glassfish-config7129008
Node: connector-j-usagenotes-troubleshooting7129243
Ref: qandaitem-31-4-5-3-17132348
Ref: qandaitem-31-4-5-3-27133643
Ref: qandaitem-31-4-5-3-37134138
Ref: qandaitem-31-4-5-3-47135981
Ref: connector-j-examples-transaction-retry7136887
Ref: qandaitem-31-4-5-3-57141591
Ref: qandaitem-31-4-5-3-67142482
Ref: qandaitem-31-4-5-3-77142959
Ref: qandaitem-31-4-5-3-87144267
Ref: qandaitem-31-4-5-3-97145113
Ref: qandaitem-31-4-5-3-107145525
Node: connector-j-support7146342
Node: connector-j-support-community7146711
Node: connector-j-support-bug-report7147624
Node: connector-j-support-changelog7152509
Node: connector-mxj7152817
Node: connector-mxj-overview7154453
Node: connector-mxj-versions7156583
Node: connector-mxj-install7158605
Node: connector-mxj-install-platforms7159958
Node: connector-mxj-install-base7161316
Node: connector-mxj-install-quickstart7164191
Node: connector-mxj-install-class7167042
Node: connector-mxj-install-jboss7168072
Node: connector-mxj-installation-test7169780
Node: connector-mxj-installation-test-requirements7170303
Node: connector-mxj-installation-test-running7171724
Node: connector-mxj-configuration7173359
Node: connector-mxj-configuration-driver-launched7173795
Node: connector-mxj-configuration-java-object7176757
Node: connector-mxj-configuration-options7181278
Node: connector-mxj-ref7182701
Node: connector-mxj-ref-mysqldresource-ctor7183153
Node: connector-mxj-ref-mysqldresource-methods7184688
Node: connector-mxj-usagenotes7186496
Node: connector-mxj-usagenotes-packaging7187166
Node: connector-mxj-usagenotes-customdb7192055
Node: connector-mxj-usagenotes-jmx-agent7194097
Node: connector-mxj-usagenotes-standard-environment7196259
Node: connector-mxj-support7200101
Node: connector-mxj-support-community7200724
Node: connector-mxj-support-bug-report7201576
Node: connector-mxj-support-changelog7202467
Node: connector-php7202798
Node: extending-mysql7203431
Node: mysql-internals7203864
Node: mysql-threads7204892
Node: mysql-test-suite7208202
Node: plugin-api7210969
Node: plugin-api-characteristics7212992
Node: plugin-full-text-plugins7217784
Node: plugin-writing7221814
Node: plugin-api-general7223247
Node: plugin-api-type-specific7229173
Node: plugin-creating7238826
Node: adding-functions7264686
Node: udf-features7267240
Node: adding-udf7268130
Node: udf-calling7273986
Node: udf-aggr-calling7278534
Node: udf-arguments7282051
Node: udf-return-values7288413
Node: udf-compiling7290307
Node: udf-security7296372
Node: adding-native-function7298002
Node: adding-procedures7302732
Node: procedure-analyse7303436
Node: writing-a-procedure7304972
Node: porting7305373
Node: debugging-server7308992
Node: compiling-for-debugging7311187
Node: making-trace-files7313764
Node: making-windows-dumps7315619
Node: using-gdb-on-mysqld7317485
Node: using-stack-trace7320742
Node: using-log-files7323731
Node: reproducible-test-case7326344
Node: debugging-client7328481
Node: the-dbug-package7329702
Node: rts-threads7334036
Node: thread-packages7337044
Node: faqs7339505
Node: faqs-general7340652
Ref: qandaitem-33-1-17341626
Ref: qandaitem-33-1-27341968
Ref: qandaitem-33-1-37342043
Ref: qandaitem-33-1-47342471
Ref: qandaitem-33-1-57342931
Ref: qandaitem-33-1-67343423
Ref: qandaitem-33-1-77343803
Ref: qandaitem-33-1-87343990
Ref: qandaitem-33-1-97344133
Ref: qandaitem-33-1-107344550
Node: faqs-storage-engines7344927
Ref: qandaitem-33-2-17345568
Ref: qandaitem-33-2-27346126
Ref: qandaitem-33-2-37346486
Ref: qandaitem-33-2-47346718
Ref: qandaitem-33-2-57347015
Node: faqs-sql-modes7347350
Ref: qandaitem-33-3-17347979
Ref: qandaitem-33-3-27348380
Ref: qandaitem-33-3-37348555
Ref: qandaitem-33-3-47348955
Ref: qandaitem-33-3-57349231
Ref: qandaitem-33-3-67349569
Ref: qandaitem-33-3-77350019
Node: faqs-stored-procs7350245
Ref: qandaitem-33-4-17352834
Ref: qandaitem-33-4-27352989
Ref: qandaitem-33-4-37353118
Ref: qandaitem-33-4-47353276
Ref: qandaitem-33-4-57353669
Ref: qandaitem-33-4-67354125
Ref: qandaitem-33-4-77354702
Ref: qandaitem-33-4-87355262
Ref: qandaitem-33-4-97355396
Ref: qandaitem-33-4-107355472
Ref: qandaitem-33-4-117355634
Ref: qandaitem-33-4-127355757
Ref: qandaitem-33-4-137355965
Ref: qandaitem-33-4-147356145
Ref: qandaitem-33-4-157356584
Ref: qandaitem-33-4-167356673
Ref: qandaitem-33-4-177356856
Ref: qandaitem-33-4-187356944
Ref: qandaitem-33-4-197357093
Ref: qandaitem-33-4-207357405
Ref: qandaitem-33-4-217357904
Ref: qandaitem-33-4-227358072
Ref: qandaitem-33-4-237358382
Ref: qandaitem-33-4-247358753
Ref: qandaitem-33-4-257359173
Ref: qandaitem-33-4-267359928
Ref: qandaitem-33-4-277361261
Ref: qandaitem-33-4-287361440
Node: faqs-triggers7362095
Ref: qandaitem-33-5-17363106
Ref: qandaitem-33-5-27363204
Ref: qandaitem-33-5-37363332
Ref: qandaitem-33-5-47363606
Ref: qandaitem-33-5-57363808
Ref: qandaitem-33-5-67364182
Ref: qandaitem-33-5-77364754
Ref: qandaitem-33-5-87364891
Ref: qandaitem-33-5-97364952
Ref: qandaitem-33-5-107365175
Ref: qandaitem-33-5-117365270
Ref: qandaitem-33-5-127365478
Ref: qandaitem-33-5-137365929
Node: faqs-views7366764
Ref: qandaitem-33-6-17367344
Ref: qandaitem-33-6-27367433
Ref: qandaitem-33-6-37367580
Ref: qandaitem-33-6-47367891
Ref: qandaitem-33-6-57367949
Ref: qandaitem-33-6-67368010
Node: faqs-information-schema7368277
Ref: qandaitem-33-7-17368979
Ref: qandaitem-33-7-27369103
Ref: qandaitem-33-7-37369255
Ref: qandaitem-33-7-47369654
Ref: qandaitem-33-7-57370033
Node: faqs-migration7370361
Ref: qandaitem-33-8-17370772
Ref: qandaitem-33-8-27371329
Node: faqs-security7372280
Ref: qandaitem-33-9-17372925
Ref: qandaitem-33-9-27373718
Ref: qandaitem-33-9-37374190
Ref: qandaitem-33-9-47374578
Ref: qandaitem-33-9-57374872
Node: faqs-mysql-cluster7375140
Ref: qandaitem-33-10-17378807
Ref: qandaitem-33-10-27380127
Ref: qandaitem-33-10-37380304
Ref: qandaitem-33-10-47381560
Ref: qandaitem-33-10-57382214
Ref: qandaitem-33-10-67382958
Ref: qandaitem-33-10-77384888
Ref: qandaitem-33-10-87385567
Ref: qandaitem-33-10-97386216
Ref: qandaitem-33-10-107390427
Ref: qandaitem-33-10-117391578
Ref: qandaitem-33-10-127392209
Ref: qandaitem-33-10-137393202
Ref: qandaitem-33-10-147394288
Ref: qandaitem-33-10-157395130
Ref: qandaitem-33-10-167395565
Ref: qandaitem-33-10-177395833
Ref: qandaitem-33-10-187396441
Ref: qandaitem-33-10-197396941
Ref: qandaitem-33-10-207397184
Ref: qandaitem-33-10-217398226
Ref: qandaitem-33-10-227399255
Ref: qandaitem-33-10-237400989
Ref: qandaitem-33-10-247401749
Ref: qandaitem-33-10-257402382
Ref: qandaitem-33-10-267404490
Ref: qandaitem-33-10-277405491
Ref: qandaitem-33-10-287407384
Ref: qandaitem-33-10-297407621
Ref: qandaitem-33-10-307408098
Ref: qandaitem-33-10-317408598
Ref: qandaitem-33-10-327409222
Ref: qandaitem-33-10-337409592
Ref: qandaitem-33-10-347410164
Node: faqs-cjk7410440
Ref: qandaitem-33-11-17412800
Ref: qandaitem-33-11-27415770
Ref: qandaitem-33-11-37421310
Ref: qandaitem-33-11-47422385
Ref: qandaitem-33-11-57425265
Ref: qandaitem-33-11-67425583
Ref: qandaitem-33-11-77426009
Ref: qandaitem-33-11-87426245
Ref: qandaitem-33-11-97427165
Ref: qandaitem-33-11-107429391
Ref: qandaitem-33-11-117432041
Ref: qandaitem-33-11-127436417
Ref: qandaitem-33-11-137438292
Ref: qandaitem-33-11-147441155
Ref: qandaitem-33-11-157444469
Ref: qandaitem-33-11-167446409
Ref: qandaitem-33-11-177447601
Ref: qandaitem-33-11-187448122
Ref: qandaitem-33-11-197448730
Ref: qandaitem-33-11-207449071
Node: faqs-connectors-apis7449731
Node: faqs-replication7450244
Node: faqs-mysql-drbd-heartbeat7450542
Node: faqs-drbd7451315
Ref: qandaitem-33-14-1-17452075
Ref: qandaitem-33-14-1-27452535
Ref: qandaitem-33-14-1-37453037
Ref: qandaitem-33-14-1-47453114
Ref: qandaitem-33-14-1-57453208
Ref: qandaitem-33-14-1-67453382
Node: drbd-linux-heartbeat7453524
Ref: qandaitem-33-14-2-17454084
Ref: qandaitem-33-14-2-27455013
Ref: qandaitem-33-14-2-37455109
Ref: qandaitem-33-14-2-47455221
Node: drbd-architecture7455406
Ref: qandaitem-33-14-3-17456238
Ref: qandaitem-33-14-3-27456408
Ref: qandaitem-33-14-3-37456647
Ref: qandaitem-33-14-3-47457092
Ref: qandaitem-33-14-3-57457539
Ref: qandaitem-33-14-3-67457703
Ref: qandaitem-33-14-3-77457866
Node: drbd-mysql-replication-scale7458313
Ref: qandaitem-33-14-4-17458912
Ref: qandaitem-33-14-4-27459386
Ref: qandaitem-33-14-4-37459851
Ref: active-master-mysql-server7460939
Node: drbd-file-systems7460985
Ref: qandaitem-33-14-5-17461376
Node: drbd-lvm7461491
Ref: qandaitem-33-14-6-17462003
Ref: qandaitem-33-14-6-27462254
Ref: qandaitem-33-14-6-37462572
Node: drbd-virtualization7462786
Ref: qandaitem-33-14-7-17463224
Ref: qandaitem-33-14-7-27463337
Node: drbd-security7463574
Ref: qandaitem-33-14-8-17464030
Ref: qandaitem-33-14-8-27464225
Node: drbd-system-requirements7464367
Ref: qandaitem-33-14-9-17464916
Ref: qandaitem-33-14-9-27465780
Ref: qandaitem-33-14-9-37466114
Node: drbd-support-consulting7466311
Ref: qandaitem-33-14-10-17467209
Ref: qandaitem-33-14-10-27467559
Ref: qandaitem-33-14-10-37468155
Ref: qandaitem-33-14-10-47468412
Ref: qandaitem-33-14-10-57468694
Ref: qandaitem-33-14-10-67468827
Node: error-handling7469078
Node: problems7470028
Node: what-is-crashing7470889
Node: common-errors7475095
Node: error-access-denied7476755
Node: can-not-connect-to-server7477143
Node: can-not-connect-to-server-on-windows7484965
Node: error-lost-connection7487786
Node: old-client7489556
Node: password-too-long7492946
Node: blocked-host7493867
Node: too-many-connections7495203
Node: out-of-memory7496927
Node: gone-away7497848
Node: packet-too-large7504791
Node: communication-errors7507190
Node: full-table7510053
Node: cannot-create7515242
Node: commands-out-of-sync7516728
Node: ignoring-user7517441
Node: cannot-find-table7518808
Node: cannot-initialize-character-set7519788
Node: not-enough-file-handles7521426
Node: table-corruption7524109
Node: installation-issues7524852
Node: link-errors7525189
Node: file-permissions7528371
Node: administration-issues7529621
Node: resetting-permissions7530219
Node: resetting-permissions-windows7530997
Node: resetting-permissions-unix7534073
Node: crashing7537981
Node: full-disk7546314
Node: temporary-files7548533
Node: problems-with-mysql-sock7551091
Node: timezone-problems7553294
Node: query-issues7554154
Node: case-sensitivity7554879
Node: using-date7559284
Node: problems-with-null7563875
Node: problems-with-alias7567249
Node: non-transactional-tables7568299
Node: deleting-from-related-tables7570272
Node: no-matching-rows7570977
Node: problems-with-float7572974
Node: optimizer-issues7576435
Node: table-definition-issues7578344
Node: alter-table-problems7578737
Node: change-column-order7580532
Node: temporary-table-problems7582121
Node: bugs7583354
Node: open-bugs7583909
Node: open-bugs-general7584909
Node: error-messages-server7594769
Node: error-messages-client7679851
Node: news7686953
Node: news-5-1-x7689139
Node: news-5-1-287691755
Node: news-5-1-277697616
Node: news-5-1-267698261
Node: news-5-1-257700548
Node: news-5-1-24-maria7714431
Node: news-5-1-247715221
Node: news-5-1-237780271
Node: news-5-1-227885426
Node: news-5-1-217889952
Node: news-5-1-207942448
Node: news-5-1-197983800
Node: news-5-1-187997489
Node: news-5-1-178049755
Node: news-5-1-168084631
Node: news-5-1-158107193
Node: news-5-1-148143812
Node: news-5-1-138167239
Node: news-5-1-128185480
Node: news-5-1-118312215
Node: news-5-1-108328327
Node: news-5-1-98358795
Node: news-5-1-88367365
Node: news-5-1-78398656
Node: news-5-1-68417328
Node: news-5-1-58433142
Node: news-5-1-48437284
Node: news-5-1-38443406
Node: news-5-1-28448898
Node: news-5-1-18449906
Node: myodbc-news8451074
Node: myodbc-news-5-1-58454274
Node: myodbc-news-5-1-48455841
Node: myodbc-news-5-1-38456966
Node: myodbc-news-5-1-28460035
Node: myodbc-news-5-1-18465014
Node: myodbc-news-5-1-08470313
Node: myodbc-news-5-0-128471948
Node: myodbc-news-5-0-118472675
Node: myodbc-news-5-0-108473750
Node: myodbc-news-5-0-98475036
Node: myodbc-news-5-0-88476282
Node: myodbc-news-5-0-78478003
Node: myodbc-news-5-0-68478799
Node: myodbc-news-5-0-58479780
Node: myodbc-news-5-0-38480385
Node: myodbc-news-5-0-28480954
Node: myodbc-news-5-0-18481258
Node: myodbc-news-3-51-268482828
Node: myodbc-news-3-51-258483721
Node: myodbc-news-3-51-248485045
Node: myodbc-news-3-51-238488852
Node: myodbc-news-3-51-228490715
Node: myodbc-news-3-51-218492184
Node: myodbc-news-3-51-208494272
Node: myodbc-news-3-51-198495459
Node: myodbc-news-3-51-188496173
Node: myodbc-news-3-51-178502586
Node: myodbc-news-3-51-168507272
Node: myodbc-news-3-51-158509344
Node: myodbc-news-3-51-148511093
Node: myodbc-news-3-51-138513469
Node: myodbc-news-3-51-128513797
Node: myodbc-news-3-51-118514550
Node: connector-net-news8515265
Node: connector-net-news-5-3-08519404
Node: connector-net-news-5-2-38519941
Node: connector-net-news-5-2-28524238
Node: connector-net-news-5-2-18527465
Node: connector-net-news-5-2-08529703
Node: connector-net-news-5-1-78533169
Node: connector-net-news-5-1-68536088
Node: connector-net-news-5-1-58538564
Node: connector-net-news-5-1-48540937
Node: connector-net-news-5-1-38544964
Node: connector-net-news-5-1-28547733
Node: connector-net-news-5-1-18549095
Node: connector-net-news-5-1-08550704
Node: connector-net-news-5-0-108551497
Node: connector-net-news-5-0-98553476
Node: connector-net-news-5-0-88556354
Node: connector-net-news-5-0-78560177
Node: connector-net-news-5-0-68562696
Node: connector-net-news-5-0-58563838
Node: connector-net-news-5-0-48568569
Node: connector-net-news-5-0-38568907
Node: connector-net-news-5-0-28571633
Node: connector-net-news-5-0-18574466
Node: connector-net-news-5-0-08576617
Node: connector-net-news-1-0-118577978
Node: connector-net-news-1-0-108579812
Node: connector-net-news-1-0-98581617
Node: connector-net-news-1-0-88585998
Node: connector-net-news-1-0-78590626
Node: connector-net-news-1-0-68592380
Node: connector-net-news-1-0-58593250
Node: connector-net-news-1-0-48595827
Node: connector-net-news-1-0-38597327
Node: connector-net-news-1-0-28599631
Node: connector-net-news-1-0-18601168
Node: connector-net-news-1-0-08605091
Node: connector-net-0-9-08605749
Node: connector-net-news-0-768613618
Node: connector-net-news-0-758615519
Node: connector-net-0-748617365
Node: connector-net-news-0-718622028
Node: connector-net-news-0-708622813
Node: connector-net-news-0-688627963
Node: connector-net-news-0-658629005
Node: connector-net-news-0-608629653
Node: connector-net-news-0-508630150
Node: vstudio-plugin-news8630581
Node: vstudio-plugin-news-1-0-38631373
Node: vstudio-plugin-news-1-0-28631914
Node: vstudio-plugin-news-1-0-18632679
Node: vstudio-plugin-news-1-0-08633952
Node: cj-news8634386
Node: cj-news-5-18635074
Node: cj-news-5-1-78635936
Node: cj-news-5-1-68636356
Node: cj-news-5-1-58646696
Node: cj-news-5-1-48647985
Node: cj-news-5-1-38648234
Node: cj-news-5-1-28658277
Node: cj-news-5-1-18658979
Node: cj-news-5-1-08662868
Node: cj-news-5-08666906
Node: cj-news-5-0-88667851
Node: cj-news-5-0-78673820
Node: cj-news-5-0-68679548
Node: cj-news-5-0-58689798
Node: cj-news-5-0-48701124
Node: cj-news-5-0-38703680
Node: cj-news-5-0-28704770
Node: cj-news-5-0-18707284
Node: cj-news-5-0-08707545
Node: cg-news-3-18712256
Node: cj-news-3-1-158713812
Node: cj-news-3-1-148714753
Node: cj-news-3-1-138718685
Node: cj-news-3-1-128725046
Node: cj-news-3-1-118731739
Node: cj-news-3-1-108742838
Node: cj-news-3-1-98743431
Node: cj-news-3-1-88751859
Node: cj-news-3-1-78759471
Node: cj-news-3-1-68765355
Node: cj-news-3-1-58765925
Node: cj-news-3-1-48770870
Node: cj-news-3-1-38775071
Node: cj-news-3-1-28776874
Node: cj-news-3-1-18780128
Node: cj-news-3-1-08786883
Node: cg-news-3-08787666
Node: cj-news-3-0-178789395
Node: cj-news-3-0-168793727
Node: cj-news-3-0-158795314
Node: cj-news-3-0-148798903
Node: cj-news-3-0-138799172
Node: cj-news-3-0-128799782
Node: cj-news-3-0-118804017
Node: cj-news-3-0-108805713
Node: cj-news-3-0-98810753
Node: cj-news-3-0-88815900
Node: cj-news-3-0-78817668
Node: cj-news-3-0-68819337
Node: cj-news-3-0-58820891
Node: cj-news-3-0-48821986
Node: cj-news-3-0-38823063
Node: cj-news-3-0-28825532
Node: cj-news-3-0-18828881
Node: cj-news-3-0-08830202
Node: cj-news-2-08832196
Node: cj-news-2-0-148833677
Node: cj-news-2-0-138834601
Node: cj-news-2-0-128835466
Node: cj-news-2-0-118837083
Node: cj-news-2-0-108837614
Node: cj-news-2-0-98838067
Node: cj-news-2-0-88839789
Node: cj-news-2-0-78840549
Node: cj-news-2-0-68842368
Node: cj-news-2-0-58842716
Node: cj-news-2-0-38843870
Node: cj-news-2-0-18844620
Node: cj-news-2-0pre58845589
Node: cj-news-2-0pre48845868
Node: cj-news-2-0pre8846992
Node: cj-news-1-2b8847756
Node: cg-news-1-08849503
Node: cj-news-1-2a8850775
Node: cj-news-1-1i8851778
Node: cj-news-1-1h8852158
Node: cj-news-1-1g8853565
Node: cj-news-1-1f8854098
Node: cj-news-1-1b8855112
Node: cj-news-1-18856338
Node: cj-news-1-08857577
Node: cj-news-0-9d8858281
Node: cj-news-0-98859288
Node: cj-news-0-88860507
Node: cj-news-0-78861029
Node: cj-news-0-68861432
Node: news-connector-mxj8861996
Node: news-connector-mxj-5-0-68862789
Node: news-connector-mxj-5-0-58865442
Node: news-connector-mxj-5-0-48867927
Node: news-connector-mxj-5-0-38869125
Node: news-connector-mxj-5-0-28869582
Node: news-connector-mxj-5-0-18871670
Node: news-connector-mxj-5-0-08871972
Node: mysql-proxy-news8872674
Node: mysql-proxy-news-0-6-08873066
Node: mysql-proxy-news-0-5-18875231
Node: mysql-proxy-news-0-5-08876585
Node: restrictions8876910
Node: routine-restrictions8877634
Node: cursor-restrictions8885523
Node: subquery-restrictions8887250
Node: view-restrictions8895031
Node: xa-restrictions8900226
Node: charset-restrictions8902480
Node: limits8903833
Node: joins-limits8904201
Node: column-count-limit8904514
Node: limits-windows8909511
Node: credits8911541
Node: developers8912204
Node: contributors8920248
Node: documenters-translators8928714
Node: used-libraries8931133
Node: packages8933632
Node: tools-used-to-create-mysql8934819
Node: supporters8935887

End Tag Table
